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11349166 | BACKGROUND Since 2004, several reported transfusion transmissions of variant Creutzfeldt-Jakob disease (vCJD) in the United Kingdom have reawakened concerns about the possible risk of similar transmissions of nonvariant or classic forms of CJD. STUDY DESIGN AND METHODS Patients with a CJD diagnosis and a history of donating blood were reported to the study coordinator. Through review of blood distribution and hospital records, the recipients of blood components from these donors were identified. We then determined each recipient's vital status and, if deceased, the cause(s) of death identified by matching the recipient's personal identifiers with the Centers for Disease Control and Prevention's National Death Index database. We conducted such searches after recipients were enrolled in this study and annually thereafter for those who remained alive. RESULTS The study included a total of 36 blood donors who subsequently developed CJD and 436 recipients. Through 2006, 91 of these recipients were still alive, 329 were deceased, and 16 were lost to follow-up. After transfusion, these three groups had survived a total of 2096.0 person-years. A total of 144 recipients survived 5 years or longer after transfusion and 68 of them had received blood donated 60 or fewer months before the onset of CJD in the donor. We identified no recipient with CJD. CONCLUSIONS The current results of this large, ongoing lookback study show no evidence of transfusion transmission of CJD. They reinforce the conclusion that the risk, if any, of transfusion transmission of prion disease by CJD donors is significantly lower than the comparable risk of such transmission by vCJD donors. |
11359243 | Altered DNA methylation occurs ubiquitously in human cancer from the earliest measurable stages. A cogent approach to understanding the mechanism and timing of altered DNA methylation is to analyze it in the context of carcinogenesis by a defined agent. Epstein-Barr virus (EBV) is a human oncogenic herpesvirus associated with lymphoma and nasopharyngeal carcinoma, but also used commonly in the laboratory to immortalize human B-cells in culture. Here we have performed whole-genome bisulfite sequencing of normal B-cells, activated B-cells, and EBV-immortalized B-cells from the same three individuals, in order to identify the impact of transformation on the methylome. Surprisingly, large-scale hypomethylated blocks comprising two-thirds of the genome were induced by EBV immortalization but not by B-cell activation per se. These regions largely corresponded to hypomethylated blocks that we have observed in human cancer, and they were associated with gene-expression hypervariability, similar to human cancer, and consistent with a model of epigenomic change promoting tumor cell heterogeneity. We also describe small-scale changes in DNA methylation near CpG islands. These results suggest that methylation disruption is an early and critical step in malignant transformation. |
11360768 | OBJECTIVE To evaluate the effects of dietary and lifestyle interventions in pregnancy on maternal and fetal weight and to quantify the effects of these interventions on obstetric outcomes. DESIGN Systematic review and meta-analysis. DATA SOURCES Major databases from inception to January 2012 without language restrictions. STUDY SELECTION Randomised controlled trials that evaluated any dietary or lifestyle interventions with potential to influence maternal weight during pregnancy and outcomes of pregnancy. DATA SYNTHESIS Results summarised as relative risks for dichotomous data and mean differences for continuous data. RESULTS We identified 44 relevant randomised controlled trials (7278 women) evaluating three categories of interventions: diet, physical activity, and a mixed approach. Overall, there was 1.42 kg reduction (95% confidence interval 0.95 to 1.89 kg) in gestational weight gain with any intervention compared with control. With all interventions combined, there were no significant differences in birth weight (mean difference -50 g, -100 to 0 g) and the incidence of large for gestational age (relative risk 0.85, 0.66 to 1.09) or small for gestational age (1.00, 0.78 to 1.28) babies between the groups, though by itself physical activity was associated with reduced birth weight (mean difference -60 g, -120 to -10 g). Interventions were associated with a reduced the risk of pre-eclampsia (0.74, 0.60 to 0.92) and shoulder dystocia (0.39, 0.22 to 0.70), with no significant effect on other critically important outcomes. Dietary intervention resulted in the largest reduction in maternal gestational weight gain (3.84 kg, 2.45 to 5.22 kg), with improved pregnancy outcomes compared with other interventions. The overall evidence rating was low to very low for important outcomes such as pre-eclampsia, gestational diabetes, gestational hypertension, and preterm delivery. CONCLUSIONS Dietary and lifestyle interventions in pregnancy can reduce maternal gestational weight gain and improve outcomes for both mother and baby. Among the interventions, those based on diet are the most effective and are associated with reductions in maternal gestational weight gain and improved obstetric outcomes. |
11369420 | Acute Myelogenous Leukemia (AML) is an aggressive cancer that strikes both adults and children and is frequently resistant to therapy. Thus, identifying signals needed for AML propagation is a critical step toward developing new approaches for treating this disease. Here, we show that Tetraspanin 3 is a target of the RNA binding protein Musashi 2, which plays a key role in AML. We generated Tspan3 knockout mice that were born without overt defects. However, Tspan3 deletion impaired leukemia stem cell self-renewal and disease propagation and markedly improved survival in mouse models of AML. Additionally, Tspan3 inhibition blocked growth of AML patient samples, suggesting that Tspan3 is also important in human disease. As part of the mechanism, we show that Tspan3 deficiency disabled responses to CXCL12/SDF-1 and led to defects in AML localization within the niche. These identify Tspan3 as an important regulator of aggressive leukemias and highlight a role for Tspan3 in oncogenesis. |
11411060 | Trypanosoma brucei, the causative agent of African sleeping sickness, is transmitted to its mammalian host by the tsetse. In the fly, the parasite's surface is covered with invariant procyclin, while in the mammal it resides extracellularly in its bloodstream form (BF) and is densely covered with highly immunogenic Variant Surface Glycoprotein (VSG). In the BF, the parasite varies this highly immunogenic surface VSG using a repertoire of ~2500 distinct VSG genes. Recent reports in mammalian systems point to a role for histone acetyl-lysine recognizing bromodomain proteins in the maintenance of stem cell fate, leading us to hypothesize that bromodomain proteins may maintain the BF cell fate in trypanosomes. Using small-molecule inhibitors and genetic mutants for individual bromodomain proteins, we performed RNA-seq experiments that revealed changes in the transcriptome similar to those seen in cells differentiating from the BF to the insect stage. This was recapitulated at the protein level by the appearance of insect-stage proteins on the cell surface. Furthermore, bromodomain inhibition disrupts two major BF-specific immune evasion mechanisms that trypanosomes harness to evade mammalian host antibody responses. First, monoallelic expression of the antigenically varied VSG is disrupted. Second, rapid internalization of antibodies bound to VSG on the surface of the trypanosome is blocked. Thus, our studies reveal a role for trypanosome bromodomain proteins in maintaining bloodstream stage identity and immune evasion. Importantly, bromodomain inhibition leads to a decrease in virulence in a mouse model of infection, establishing these proteins as potential therapeutic drug targets for trypanosomiasis. Our 1.25Å resolution crystal structure of a trypanosome bromodomain in complex with I-BET151 reveals a novel binding mode of the inhibitor, which serves as a promising starting point for rational drug design. |
11414664 | The insulin/IGF-1 (where IGF-1 is insulin-like growth factor-1) signaling pathway influences longevity, reproduction, and diapause in many organisms. Because of the fundamental importance of this system in animal physiology, we asked when during the animal's life it is required to regulate these different processes. We find that in Caenorhabditis elegans, the pathway acts during adulthood, to relatively advanced ages, to influence aging. In contrast, it regulates diapause during development. In addition, the pathway controls longevity and reproduction independently of one another. Together our findings show that life-span regulation can be dissociated temporally from phenotypes that might seem to decrease the quality of life. |
11420613 | The 137 ribosomal protein genes (RPGs) of Saccharomyces provide a model for gene coregulation. We examined the positional and functional organization of their regulators (Rap1 [repressor activator protein 1], Fhl1, Ifh1, Sfp1, and Hmo1), the transcription machinery (TFIIB, TFIID, and RNA polymerase II), and chromatin at near-base-pair resolution using ChIP-exo, as RPGs are coordinately reprogrammed. Where Hmo1 is enriched, Fhl1, Ifh1, Sfp1, and Hmo1 cross-linked broadly to promoter DNA in an RPG-specific manner and demarcated by general minor groove widening. Importantly, Hmo1 extended 20-50 base pairs (bp) downstream from Fhl1. Upon RPG repression, Fhl1 remained in place. Hmo1 dissociated, which was coupled to an upstream shift of the +1 nucleosome, as reflected by the Hmo1 extension and core promoter region. Fhl1 and Hmo1 may create two regulatable and positionally distinct barriers, against which chromatin remodelers position the +1 nucleosome into either an activating or a repressive state. Consistent with in vitro studies, we found that specific TFIID subunits, in addition to cross-linking at the core promoter, made precise cross-links at Rap1 sites, which we interpret to reflect native Rap1-TFIID interactions. Our findings suggest how sequence-specific DNA binding regulates nucleosome positioning and transcription complex assembly >300 bp away and how coregulation coevolved with coding sequences. |
11441172 | PURPOSE OF REVIEW Owing to the high mortality, risk of neurodevelopmental impairment and end-organ involvement with fungal infections in the neonate, prevention of invasive Candida infections in extremely preterm infants should be a priority for each neonatal ICU. RECENT FINDINGS Even with prompt or empiric treatment, mortality and neurodevelopmental impairment is high (57%) in infants <1000 g. Multiple studies have been performed with fluconazole prophylaxis, including a recent multicenter randomized controlled trial. All of the studies have demonstrated efficacy and safety with no increase or emergence of fungal resistance. Analysis of these studies demonstrates that fluconazole prophylaxis decreased the incidence of invasive Candida infections in high-risk infants <1000 g by 91% (P = 0.0004) and all infants <1500 g by 85% (P < 0.0001). The mortality rate from all causes was 25% lower (P = 0.029). Furthermore, studies have demonstrated that all Candida-related mortality can be eliminated in an entire neonatal ICU by targeting fluconazole prophylaxis in infants <1000 g. SUMMARY Targeting fluconazole prophylaxis to infants who are either <1000 g or < or =27 weeks is highly effective, safe and inexpensive, and can eliminate these infections as a cause of neurodevelopmental impairment and mortality. |
11459139 | INTRODUCTION Angiopoietin-2 (ang-2), an angiogenic peptide released by endothelial cell Weibel-Palade bodies (WPBs), increases endothelial activation and vascular permeability. Ang-2 is raised in severe sepsis but the mechanisms underlying this are not known. Nitric oxide (NO) inhibits WPB exocytosis, and bioavailability of endothelial NO is decreased in sepsis. We hypothesized that endothelial NO bioavailability would be inversely correlated with ang-2 concentrations in sepsis. METHODS Plasma ang-2, vascular endothelial growth factor (VEGF) and endothelial-active cytokines were assessed in 83 patients with early sepsis and 41 hospital controls, and related to reactive hyperaemia-peripheral arterial tonometry, RH-PAT, a measure of endothelial NO bioavailability. RESULTS Plasma Ang-2 was elevated in sepsis (median [interquartile range (IQR)], ng/ml: severe sepsis 12.4 [8.5-33.4], sepsis without organ failure 6.1 [5.0-10.4], controls 2.7 [2.2-3.6], P < 0.0001). It correlated inversely with RH-PAT (r = -0.38, P < 0.0001) and positively with IL-6 (r = 0.57, P < 0.0001) and degree of organ failure (sequential organ function assessment score) (r = 0.58, P < 0.0001). The correlation of ang-2 with RH-PAT persisted after controlling for sepsis severity. In a longitudinal mixed-effects model, recovery of RH-PAT over time was associated with decline in ang-2. CONCLUSIONS Ang-2 is elevated in proportion to sepsis severity, and inversely correlated with NO-dependent microvascular reactivity. Impaired endothelial NO bioavailability may contribute to increased endothelial cell release of ang-2, endothelial activation and capillary leak. Agents that increase endothelial NO bioavailability or inhibit WPB exocytosis and/or Ang-2 activity may have therapeutic potential in sepsis. |
11469078 | A number of authors have attempted to defend ecologic (aggregate) studies by claiming that the goal of those studies is estimation of ecologic (contextual or group-level) effects rather than individual-level effects. Critics of these attempts point out that ecologic effect estimates are inevitably used as estimates of individual effects, despite disclaimers. A more subtle problem is that ecologic variation in the distribution of individual effects can bias ecologic estimates of contextual effects. The conditions leading to this bias are plausible and perhaps even common in studies of ecosocial factors and health outcomes because social context is not randomized across typical analysis units (administrative regions). By definition, ecologic data contain only marginal observations on the joint distribution of individually defined confounders and outcomes, and so identify neither contextual nor individual-level effects. While ecologic studies can still be useful given appropriate caveats, their problems are better addressed by multilevel study designs, which obtain and use individual as well as group-level data. Nonetheless, such studies often share certain special problems with ecologic studies, including problems due to inappropriate aggregation and problems due to temporal changes in covariate distributions. |
11481946 | Epidemiological studies suggest a positive association between obesity and type 2 diabetes mellitus (T2D) with the risk of cancer and cancer-related mortality. Insulin resistance, hyperinsulinemia, increased levels of IGF, elevated levels of steroid and peptide hormones, and inflammatory markers appear to play a role in the connection between these different diseases. Medications, such as metformin and exogenous insulin, used to treat T2D may affect the risk of cancer and cancer-related mortality. Newer therapies targeting the insulin and IGF1 systems are being developed for use in cancer therapy. |
11527822 | The SIR genes are determinants of life span in yeast mother cells. Here we show that life span regulation by the Sir proteins is independent of their role in nonhomologous end joining. The short life span of a sir3 or sir4 mutant is due to the simultaneous expression of a and alpha mating-type information, which indirectly causes an increase in rDNA recombination and likely increases the production of extrachromosomal rDNA circles. The short life span of a sir2 mutant also reveals a direct failure to repress recombination generated by the Fob1p-mediated replication block in the rDNA. Sir2p is a limiting component in promoting yeast longevity, and increasing the gene dosage extends the life span in wild-type cells. A possible role of the conserved SIR2 in mammalian aging is discussed. |
11535539 | Pathological fibrosis is driven by a feedback loop in which the fibrotic extracellular matrix is both a cause and consequence of fibroblast activation. However, the molecular mechanisms underlying this process remain poorly understood. Here we identify yes-associated protein (YAP) (homolog of drosophila Yki) and transcriptional coactivator with PDZ-binding motif (TAZ) (also known as Wwtr1), transcriptional effectors of the Hippo pathway, as key matrix stiffness-regulated coordinators of fibroblast activation and matrix synthesis. YAP and TAZ are prominently expressed in fibrotic but not healthy lung tissue, with particularly pronounced nuclear expression of TAZ in spindle-shaped fibroblastic cells. In culture, both YAP and TAZ accumulate in the nuclei of fibroblasts grown on pathologically stiff matrices but not physiologically compliant matrices. Knockdown of YAP and TAZ together in vitro attenuates key fibroblast functions, including matrix synthesis, contraction, and proliferation, and does so exclusively on pathologically stiff matrices. Profibrotic effects of YAP and TAZ operate, in part, through their transcriptional target plasminogen activator inhibitor-1, which is regulated by matrix stiffness independent of transforming growth factor-β signaling. Immortalized fibroblasts conditionally expressing active YAP or TAZ mutant proteins overcome soft matrix limitations on growth and promote fibrosis when adoptively transferred to the murine lung, demonstrating the ability of fibroblast YAP/TAZ activation to drive a profibrotic response in vivo. Together, these results identify YAP and TAZ as mechanoactivated coordinators of the matrix-driven feedback loop that amplifies and sustains fibrosis. |
11568270 | Human TopBP1 is a major player in the control of the DNA replication checkpoint. In this study, we identified MDC1, a key checkpoint protein involved in the cellular response to DNA double-strand breaks, as a TopBP1-associated protein. The specific TopBP1-MDC1 interaction is mediated by the fifth BRCT domain of TopBP1 and the Ser-Asp-Thr (SDT) repeats of MDC1. In addition, we demonstrated that TopBP1 accumulation at stalled replication forks is promoted by the H2AX/MDC1 signaling cascade. Moreover, MDC1 is important for ATR-dependent Chk1 activation in response to replication stress. Collectively, our data suggest that MDC1 facilitates several important steps in both cellular DNA damage response and the DNA replication checkpoint. |
11569583 | DNA polymerase β (Pol β) is an error-prone enzyme which has been found to be overexpressed in several human tumors. By using a couple of recombinant CHO cells differing only from the exogenous expression of Pol β, we showed here that cells overexpressing Pol β are much more sensitive to IR treatments by increasing apoptosis. We also found that the surviving cells displayed an hypermutator phenotype which could be explained by different pathways involving Pol β, such as (i) an increased capacity to incorporate into DNA the mutagenic dGTP analog, 8-oxo-dGTP, one of the most abundant purine-derived nucleotides exposed to γ-irradiation, (ii) the induction of IR-induced DNA breaks and (iii) accumulation of chromosome aberrations induced by radiation. Alteration of Pol β expression in irradiated cells thus appears to strengthen both cell death and genetic changes associated with a malignant phenotype. These data provide new insights into the cellular response to radiations and the associated carcinogenic consequences. |
11578459 | BACKGROUND HOX genes are a family of developmental genes that are expressed neither in the developing forebrain nor in the normal brain. Aberrant expression of a HOX-gene dominated stem-cell signature in glioblastoma has been linked with increased resistance to chemo-radiotherapy and sustained proliferation of glioma initiating cells. Here we describe the epigenetic and genetic alterations and their interactions associated with the expression of this signature in glioblastoma. RESULTS We observe prominent hypermethylation of the HOXA locus 7p15.2 in glioblastoma in contrast to non-tumoral brain. Hypermethylation is associated with a gain of chromosome 7, a hallmark of glioblastoma, and may compensate for tumor-driven enhanced gene dosage as a rescue mechanism by preventing undue gene expression. We identify the CpG island of the HOXA10 alternative promoter that appears to escape hypermethylation in the HOX-high glioblastoma. An additive effect of gene copy gain at 7p15.2 and DNA methylation at key regulatory CpGs in HOXA10 is significantly associated with HOX-signature expression. Additionally, we show concordance between methylation status and presence of active or inactive chromatin marks in glioblastoma-derived spheres that are HOX-high or HOX-low, respectively. CONCLUSIONS Based on these findings, we propose co-evolution and interaction between gene copy gain, associated with a gain of chromosome 7, and additional epigenetic alterations as key mechanisms triggering a coordinated, but inappropriate, HOX transcriptional program in glioblastoma. |
11581157 | The invertebrate's innate immune system was reported to show some form of adaptive features, termed trained immunity. However, the memory characteristics of innate immune system and the mechanisms behind such phenomena remain unclear. Using the invertebrate model Artemia, we verified the possibility or impossibility of trained immunity, examining the presence or absence of enduring memory against homologous and heterologous antigens (Vibrio spp.) during a transgenerational study. We also determined the mechanisms behind such phenomenon. Our results showed the occurrence of memory and partial discrimination in Artemia's immune system, as manifested by increased resistance, for three successive generations, of the progenies of Vibrio-exposed ancestors towards a homologous bacterial strain, rather than to a heterologous strain. This increased resistance phenotype was associated with elevated levels of hsp70 and hmgb1 signaling molecules and alteration in the expression of key innate immunity-related genes. Our results also showed stochastic pattern in the acetylation and methylation levels of H4 and H3K4me3 histones, respectively, in the progenies whose ancestors were challenged. Overall results suggest that innate immune responses in invertebrates have the capacity to be trained, and epigenetic reprogramming of (selected) innate immune effectors is likely to have central place in the mechanisms leading to trained immunity. |
11616424 | Hypoglycemia is among the most injurious metabolic disorders caused by endotoxemia. In experimental endotoxemia with lipopolysaccharide (LPS) in animals, a marked glucose consumption is observed in macrophage-rich organs. However, the direct effect of LPS on the uptake of glucose by macrophages has not been fully understood, and the present study was undertaken to shed light on this point. The consumption and uptake of glucose, as measured with 2-deoxy-D-[3H]glucose, by murine peritoneal exudate macrophages in culture were accelerated two- to threefold by stimulation with 3 ng of LPS per ml. The rate of glucose uptake reached a plateau after 20 min of stimulation and remained at the maximum as long as LPS was present. Northern (RNA) blot analysis with cDNA probes for five known isoforms of glucose transporter (GLUT) revealed that the expression of GLUT by macrophages was restricted to the GLUT1 isoform during LPS stimulation and the amount of GLUT1 mRNA was increased by the stimulation. These results suggest that macrophage responses to LPS are supported by a rapid and sustained glucose influx via GLUT1 and that this is a participating factor in the development of systemic hypoglycemia when endotoxemia is prolonged. |
11624482 | CONTEXT Certification by an American Board of Medical Specialties (ABMS) member board is emerging as a measure of physician quality. OBJECTIVE To identify demographic and educational factors associated with ABMS member board certification of US medical school graduates. DESIGN, SETTING, AND PARTICIPANTS Retrospective study of a national cohort of 1997-2000 US medical school graduates, grouped by specialty choice at graduation and followed up through March 2, 2009. In separate multivariable logistic regression models for each specialty category, factors associated with ABMS member board certification were identified. MAIN OUTCOME MEASURE ABMS member board certification. RESULTS Of 42,440 graduates in the study sample, 37,054 (87.3%) were board certified. Graduates in all specialty categories with first-attempt passing scores in the highest tertile (vs first-attempt failing scores) on US Medical Licensing Examination Step 2 Clinical Knowledge were more likely to be board certified; adjusted odds ratios (AORs) varied by specialty category, with the lowest odds for emergency medicine (87.4% vs 73.6%; AOR, 1.82; 95% CI, 1.03-3.20) and highest odds for radiology (98.1% vs 74.9%; AOR, 13.19; 95% CI, 5.55-31.32). In each specialty category except family medicine, graduates self-identified as underrepresented racial/ethnic minorities (vs white) were less likely to be board certified, ranging from 83.5% vs 95.6% in the pediatrics category (AOR, 0.44; 95% CI, 0.33-0.58) to 71.5% vs 83.7% in the other nongeneralist specialties category (AOR, 0.79; 95% CI, 0.64-0.96). With each $50,000 unit increase in debt (vs no debt), graduates choosing obstetrics/gynecology were less likely to be board certified (AOR, 0.89; 95% CI, 0.83-0.96), and graduates choosing family medicine were more likely to be board certified (AOR, 1.13; 95% CI, 1.01-1.26). CONCLUSION Demographic and educational factors were associated with board certification among US medical school graduates in every specialty category examined; findings varied among specialty categories. |
11630388 | BACKGROUND Obesity is associated with diverse health risks, but the role of body weight as a risk factor for death remains controversial. METHODS We examined the association between body weight and the risk of death in a 12-year prospective cohort study of 1,213,829 Koreans between the ages of 30 and 95 years. We examined 82,372 deaths from any cause and 48,731 deaths from specific diseases (including 29,123 from cancer, 16,426 from atherosclerotic cardiovascular disease, and 3362 from respiratory disease) in relation to the body-mass index (BMI) (the weight in kilograms divided by the square of the height in meters). RESULTS In both sexes, the average baseline BMI was 23.2, and the rate of death from any cause had a J-shaped association with the BMI, regardless of cigarette-smoking history. The risk of death from any cause was lowest among patients with a BMI of 23.0 to 24.9. In all groups, the risk of death from respiratory causes was higher among subjects with a lower BMI, and the risk of death from atherosclerotic cardiovascular disease or cancer was higher among subjects with a higher BMI. The relative risk of death associated with BMI declined with increasing age. CONCLUSIONS Underweight, overweight, and obese men and women had higher rates of death than men and women of normal weight. The association of BMI with death varied according to the cause of death and was modified by age, sex, and smoking history. |
11666252 | The persistence of naive and memory T cells has long been of interest to immunologists, but the factors that influence the survival and homeostasis of these subsets have remained obscure. In recent years, it has become evident that the homeostasis of both naive and memory T-cell pools is highly dynamic and tightly regulated by internal stimuli, including cytokines and self-peptide–MHC ligands for the T-cell receptor. These homeostatic mechanisms might have a vital influence on the capacity of the T-cell pool to respond to both foreign and self-antigens. |
11674288 | Induced pluripotent stem cells (iPSCs) have been derived from various somatic cell populations through ectopic expression of defined factors. It remains unclear whether iPSCs generated from different cell types are molecularly and functionally similar. Here we show that iPSCs obtained from mouse fibroblasts, hematopoietic and myogenic cells exhibit distinct transcriptional and epigenetic patterns. Moreover, we demonstrate that cellular origin influences the in vitro differentiation potentials of iPSCs into embryoid bodies and different hematopoietic cell types. Notably, continuous passaging of iPSCs largely attenuates these differences. Our results suggest that early-passage iPSCs retain a transient epigenetic memory of their somatic cells of origin, which manifests as differential gene expression and altered differentiation capacity. These observations may influence ongoing attempts to use iPSCs for disease modeling and could also be exploited in potential therapeutic applications to enhance differentiation into desired cell lineages. |
11674596 | A putative spindle matrix has been hypothesized to mediate chromosome motion, but its existence and functionality remain controversial. In this report, we show that Megator (Mtor), the Drosophila melanogaster counterpart of the human nuclear pore complex protein translocated promoter region (Tpr), and the spindle assembly checkpoint (SAC) protein Mad2 form a conserved complex that localizes to a nuclear derived spindle matrix in living cells. Fluorescence recovery after photobleaching experiments supports that Mtor is retained around spindle microtubules, where it shows distinct dynamic properties. Mtor/Tpr promotes the recruitment of Mad2 and Mps1 but not Mad1 to unattached kinetochores (KTs), mediating normal mitotic duration and SAC response. At anaphase, Mtor plays a role in spindle elongation, thereby affecting normal chromosome movement. We propose that Mtor/Tpr functions as a spatial regulator of the SAC, which ensures the efficient recruitment of Mad2 to unattached KTs at the onset of mitosis and proper spindle maturation, whereas enrichment of Mad2 in a spindle matrix helps confine the action of a diffusible "wait anaphase" signal to the vicinity of the spindle. |
11710511 | Adherens junctions and their core molecular components, classic cadherins, make major contributions to animal morphogenesis. Although the significance of cadherins in development is generally accepted, the mechanisms regulating adherens junction function during morphogenesis remain a subject of intense research. Adherens junctions are involved in the organization of simple cellular patterns, and more complex cell shape changes and cell movements that depend on the dynamic modulation of adherens junctions. |
11716783 | Publisher Summary This chapter discusses the developmental roles of vascular endothelial growth factor (VEGF) in skeletal morphogenesis, speculates on the future directions of research in this area, and describes some of the challenges in the field. VEGF regulates osteoclastic differentiation, migration, and activity. VEGF is, therefore, a key coordinator of the entire process. VEGF is necessary for osteoclastic activity both at the stage when the primary ossification center is established and later during bone growth. A number of studies have led to the identification of VEGF as a critical factor for the survival of chondrocytes. Several factors with important roles in regulating bone formation also induce the expression of VEGF by osteoblasts. Prostaglandins E1 and E2, BMP-4, BMP-6, BMP-7, FGF-2, TGF-β, endothelin-1, IGF-1, and vitamin D3 can all induce VEGF expression in osteoblasts by activating a variety of signaling pathways. Bone fractures can heal in two divergent ways, similar to the two ways of forming bone during embryonic development. Stabilized fractures heal by intramembranous ossification, and unstable fractures undergo endochondral ossification. The similarity between the embryonic bone development and repair of fractured bones, coupled with the finding that VEGF is expressed at sites of bone fracture, suggests that VEGF is involved in bone repair as it is in bone development. |
11718220 | BACKGROUND Deep vein thrombosis (DVT) and pulmonary embolism are common after stroke. In small trials of patients undergoing surgery, graduated compression stockings (GCS) reduce the risk of DVT. National stroke guidelines extrapolating from these trials recommend their use in patients with stroke despite insufficient evidence. We assessed the effectiveness of thigh-length GCS to reduce DVT after stroke. METHODS In this outcome-blinded, randomised controlled trial, 2518 patients who were admitted to hospital within 1 week of an acute stroke and who were immobile were enrolled from 64 centres in the UK, Italy, and Australia. Patients were allocated via a central randomisation system to routine care plus thigh-length GCS (n=1256) or to routine care plus avoidance of GCS (n=1262). A technician who was blinded to treatment allocation undertook compression Doppler ultrasound of both legs at about 7-10 days and, when practical, again at 25-30 days after enrolment. The primary outcome was the occurrence of symptomatic or asymptomatic DVT in the popliteal or femoral veins. Analyses were by intention to treat. This study is registered, number ISRCTN28163533. FINDINGS All patients were included in the analyses. The primary outcome occurred in 126 (10.0%) patients allocated to thigh-length GCS and in 133 (10.5%) allocated to avoid GCS, resulting in a non-significant absolute reduction in risk of 0.5% (95% CI -1.9% to 2.9%). Skin breaks, ulcers, blisters, and skin necrosis were significantly more common in patients allocated to GCS than in those allocated to avoid their use (64 [5%] vs 16 [1%]; odds ratio 4.18, 95% CI 2.40-7.27). INTERPRETATION These data do not lend support to the use of thigh-length GCS in patients admitted to hospital with acute stroke. National guidelines for stroke might need to be revised on the basis of these results. FUNDING Medical Research Council (UK), Chief Scientist Office of Scottish Government, Chest Heart and Stroke Scotland, Tyco Healthcare (Covidien) USA, and UK Stroke Research Network. |
11721286 | BACKGROUND Streptococcus pneumoniae infection starts from colonization of the host respiratory tract where interaction with host respiratory tract epithelial cells occurs. To investigate pneumococcal genes that are involved in the early stage of interaction with host epithelial cells, transcriptional responses of an encapsulated pathogenic pneumococcal strain TIGR4 upon exposure to human lung epithelial cells A549 for 0.5 h and 1 h time periods were investigated by using TIGR (JCVI) microarray technology. Gene expression changes were validated by quantitative real-time PCR (qRT-PCR) analysis. FINDINGS We observed different transcriptional profiles at two incubation time periods in which most gene expressions were down-regulated at 0.5 h but up-regulated at 1 h. Many genes associated with ribonucleotide biosynthesis were down-regulated at both time points, whereas the genes associated with cell envelope, energy metabolism, transport and protein synthesis were mostly up-regulated at 1 h. Furthermore, these profiles were compared to the transcriptomes of a TIGR4-derived strain in response to human macrophages for the same time periods. We found one set of genes that exhibited similar expression changes upon exposure to both types of host cells, including cell envelope-associated bgaA (SP0648) and nanA (SP1693), and uncharacterized gene clusters such as SP1677-SP1680 and SP1688-SP1690. CONCLUSION These data indicate that at the early stage of interaction with host epithelial cells, a complex gene regulation and expression change occur in bacteria. Some of them might play an essential role during pathogen-host interactions and for the establishment of infection. |
11728637 | The FASTA package of sequence comparison programs has been modified to provide accurate statistical estimates for local sequence similarity scores with gaps. These estimates are derived using the extreme value distribution from the mean and variance of the local similarity scores of unrelated sequences after the scores have been corrected for the expected effect of library sequence length. This approach allows accurate estimates to be calculated for both FASTA and Smith-Waterman similarity scores for protein/protein, DNA/DNA, and protein/translated-DNA comparisons. The accuracy of the statistical estimates is summarized for 54 protein families using FASTA and Smith-Waterman scores. Probability estimates calculated from the distribution of similarity scores are generally conservative, as are probabilities calculated using the Altschul-Gish lambda, kappa, and eta parameters. The performance of several alternative methods for correcting similarity scores for library-sequence length was evaluated using 54 protein superfamilies from the PIR39 database and 110 protein families from the Prosite/SwissProt rel. 34 database. Both regression-scaled and Altschul-Gish scaled scores perform significantly better than unscaled Smith-Waterman or FASTA similarity scores. When the Prosite/ SwissProt test set is used, regression-scaled scores perform slightly better; when the PIR database is used, Altschul-Gish scaled scores perform best. Thus, length-corrected similarity scores improve the sensitivity of database searches. Statistical parameters that are derived from the distribution of similarity scores from the thousands of unrelated sequences typically encountered in a database search provide accurate estimates of statistical significance that can be used to infer sequence homology. |
11738716 | Dietary restriction (DR) increases healthspan and longevity in many species, including primates, but it is often accompanied by impaired reproductive function. Whether signals associated with the reproductive system contribute to or are required for DR effects on lifespan has not been established. Here we show that expression of the cytochrome P450 DAF-9/CYP450 and production of the steroid hormone Δ(7)-dafachronic acid (DA) are increased in C. elegans subjected to DR. DA signalling through the non-canonical nuclear hormone receptor NHR-8/NHR and the nutrient-responsive kinase let-363/mTOR is essential for DR-mediated longevity. Steroid signalling also affects germline plasticity in response to nutrient deprivation and this is required to achieve lifespan extension. These data demonstrate that steroid signalling links germline physiology to lifespan when nutrients are limited, and establish a central role for let-363/mTOR in integrating signals derived from nutrients and steroid hormones. |
11742219 | Galanin (GAL) is known to stimulate feeding behavior. This peptide has different properties and functions from other feeding stimulants, e.g., neuropeptide Y and agouti-related protein. Hypothalamic GAL is relatively unresponsive to food deprivation and to changes in corticosterone, glucose utilization, dietary carbohydrate and leptin. This indicates that this peptide is not essential under conditions when food is scarce or low-energy, high-carbohydrate diets are being consumed. In contrast, recent evidence suggests that GAL in the paraventricular nucleus (PVN) functions in close relation to dietary fat and alcohol. In particular, it mediates functions that allow animals to adapt to conditions of positive energy balance involving excess consumption of these nutrients. This peptide in the PVN is stimulated by a high-fat diet and also by alcohol. It is stimulated by an increase in circulating lipids caused by a fat-rich meal or alcohol consumption, and it rises during the middle of the active feeding cycle, when fat consumption and triglycerides naturally rise. When centrally injected, GAL in the PVN increases the consumption of food and alcohol. Moreover, it produces a significantly stronger feeding response in rats maintained on a fat-rich diet, which also promotes alcohol intake. This evidence supports the existence of non-homeostatic, positive feedback circuits between GAL and both dietary fat and alcohol. These circuits are believed to contribute to the large meal size, over-consumption of alcohol, and obesity which are generally associated with fat-rich foods. |
11748341 | Maternal undernutrition contributes to 800,000 neonatal deaths annually through small for gestational age births; stunting, wasting, and micronutrient deficiencies are estimated to underlie nearly 3·1 million child deaths annually. Progress has been made with many interventions implemented at scale and the evidence for effectiveness of nutrition interventions and delivery strategies has grown since The Lancet Series on Maternal and Child Undernutrition in 2008. We did a comprehensive update of interventions to address undernutrition and micronutrient deficiencies in women and children and used standard methods to assess emerging new evidence for delivery platforms. We modelled the effect on lives saved and cost of these interventions in the 34 countries that have 90% of the world's children with stunted growth. We also examined the effect of various delivery platforms and delivery options using community health workers to engage poor populations and promote behaviour change, access and uptake of interventions. Our analysis suggests the current total of deaths in children younger than 5 years can be reduced by 15% if populations can access ten evidence-based nutrition interventions at 90% coverage. Additionally, access to and uptake of iodised salt can alleviate iodine deficiency and improve health outcomes. Accelerated gains are possible and about a fifth of the existing burden of stunting can be averted using these approaches, if access is improved in this way. The estimated total additional annual cost involved for scaling up access to these ten direct nutrition interventions in the 34 focus countries is Int$9·6 billion per year. Continued investments in nutrition-specific interventions to avert maternal and child undernutrition and micronutrient deficiencies through community engagement and delivery strategies that can reach poor segments of the population at greatest risk can make a great difference. If this improved access is linked to nutrition-sensitive approaches--ie, women's empowerment, agriculture, food systems, education, employment, social protection, and safety nets--they can greatly accelerate progress in countries with the highest burden of maternal and child undernutrition and mortality. |
11771811 | Maintenance of normal endothelial function is critical to various aspects of blood vessel function, but its regulation is poorly understood. In this study, we show that disruption of baseline fibroblast growth factor (FGF) signaling to the endothelium leads to a dramatic reduction in let-7 miRNA levels that, in turn, increases expression of transforming growth factor (TGF)-β ligands and receptors and activation of TGF-β signaling, leading to endothelial-to-mesenchymal transition (Endo-MT). We also find that Endo-MT is an important driver of neointima formation in a murine transplant arteriopathy model and in rejection of human transplant lesions. The decline in endothelial FGF signaling input is due to the appearance of an FGF resistance state that is characterized by inflammation-dependent reduction in expression and activation of key components of the FGF signaling cascade. These results establish FGF signaling as a critical factor in maintenance of endothelial homeostasis and point to an unexpected role of Endo-MT in vascular pathology. |
11784947 | Short interfering RNAs (siRNAs) have been used to inhibit HIV-1 replication. The durable inhibition of HIV-1 replication by RNA interference has been impeded, however, by a high mutation rate when viral sequences are targeted and by cytotoxicity when cellular genes are knocked down. To identify cellular proteins that contribute to HIV-1 replication that can be chronically silenced without significant cytotoxicity, we employed a shRNA library that targets 54,509 human transcripts. We used this library to select a comprehensive population of Jurkat T-cell clones, each expressing a single discrete shRNA. The Jurkat clones were then infected with HIV-1. Clones that survived viral infection represent moieties silenced for a human mRNA needed for virus replication, but whose chronic knockdown did not cause cytotoxicity. Overall, 252 individual Jurkat mRNAs were identified. Twenty-two of these mRNAs were secondarily verified for their contributions to HIV-1 replication. Five mRNAs, NRF1, STXBP2, NCOA3, PRDM2, and EXOSC5, were studied for their effect on steps of the HIV-1 life cycle. We discuss the similarities and differences between our shRNA findings for HIV-1 using a spreading infection assay in human Jurkat T-cells and results from other investigators who used siRNA-based screenings in HeLa or 293T cells. |
11837657 | Mycobacterium tuberculosis (Mtb) infects lung macrophages, which instead of killing the pathogen can be manipulated by the bacilli, creating an environment suitable for intracellular replication and spread to adjacent cells. The role of host cell death during Mtb infection is debated because the bacilli have been shown to be both anti-apoptotic, keeping the host cell alive to avoid the antimicrobial effects of apoptosis, and pro-necrotic, killing the host macrophage to allow infection of neighboring cells. Since mycobacteria activate the NLRP3 inflammasome in macrophages, we investigated whether Mtb could induce one of the recently described inflammasome-linked cell death modes pyroptosis and pyronecrosis. These are mediated through caspase-1 and cathepsin-B, respectively. Human monocyte-derived macrophages were infected with virulent (H37Rv) Mtb at a multiplicity of infection (MOI) of 1 or 10. The higher MOI resulted in strongly enhanced release of IL-1β, while a low MOI gave no IL-1β response. The infected macrophages were collected and cell viability in terms of the integrity of DNA, mitochondria and the plasma membrane was determined. We found that infection with H37Rv at MOI 10, but not MOI 1, over two days led to extensive DNA fragmentation, loss of mitochondrial membrane potential, loss of plasma membrane integrity, and HMGB1 release. Although we observed plasma membrane permeabilization and IL-1β release from infected cells, the cell death induced by Mtb was not dependent on caspase-1 or cathepsin B. It was, however, dependent on mycobacterial expression of ESAT-6. We conclude that as virulent Mtb reaches a threshold number of bacilli inside the human macrophage, ESAT-6-dependent necrosis occurs, activating caspase-1 in the process. |
11844826 | MURR1 is a multifunctional protein that inhibits nuclear factor kappaB (NF-kappaB), a transcription factor with pleiotropic functions affecting innate and adaptive immunity, apoptosis, cell cycle regulation, and oncogenesis. Here we report the discovery of a new family of proteins with homology to MURR1. These proteins form multimeric complexes and were identified in a biochemical screen for MURR1-associated factors. The family is defined by the presence of a conserved and unique motif termed the COMM (copper metabolism gene MURR1) domain, which functions as an interface for protein-protein interactions. Like MURR1, several of these factors also associate with and inhibit NF-kappaB. The proteins designated as COMMD or COMM domain containing 1-10 are extensively conserved in multicellular eukaryotic organisms and define a novel family of structural and functional homologs of MURR1. The prototype of this family, MURR1/COMMD1, suppresses NF-kappaB not by affecting nuclear translocation or binding of NF-kappaB to cognate motifs; rather, it functions in the nucleus by affecting the association of NF-kappaB with chromatin. |
11880289 | BACKGROUND Age-specific effects of mammographic screening, and the timing of such effects, are a matter of debate. The results of the UK Age trial, which compared the effect of invitation to annual mammographic screening from age 40 years with commencement of screening at age 50 years on breast cancer mortality, have been reported at 10 years of follow-up and showed no significant difference in mortality between the trial groups. Here, we report the results of the UK Age trial after 17 years of follow-up. METHODS Women aged 39-41 from 23 UK NHS Breast Screening Programme units years were randomly assigned by individual randomisation (1:2) to either an intervention group offered annual screening by mammography up to and including the calendar year of their 48th birthday or to a control group receiving usual medical care (invited for screening at age 50 years and every 3 years thereafter). Both groups were stratified by general practice. We compared breast cancer incidence and mortality by time since randomisation. Analyses included all women randomly assigned who could be traced with the National Health Service Central Register and who had not died or emigrated before entry. The primary outcome measures were mortality from breast cancer (defined as deaths with breast cancer coded as the underlying cause of death) and breast cancer incidence, including in-situ, invasive, and total incidence. Because there is an interest in the timing of the mortality effect, we analysed the results in different follow-up periods. This trial is registered, number ISRCTN24647151. FINDINGS Between Oct 14, 1990, and Sept 25, 1997, 160 921 participants were randomly assigned; 53 883 women in the intervention group and 106 953 assigned to usual medical care were included in this analysis. After a median follow-up of 17 years (IQR 16·8-18·8), the rate ratio (RR) for breast cancer mortality was 0·88 (95% CI 0·74-1·04) from tumours diagnosed during the intervention phase. A significant reduction in breast cancer mortality was noted in the intervention group compared with the control group in the first 10 years after diagnosis (RR 0·75, 0·58-0·97) but not thereafter (RR 1·02, 0·80-1·30) from tumours diagnosed during the intervention phase. The overall breast cancer incidence during 17 year follow-up was similar between the intervention group and the control group (RR 0·98, 0·93-1·04). INTERPRETATION Our results support an early reduction in mortality from breast cancer with annual mammography screening in women aged 40-49 years. Further data are needed to fully understand long-term effects. Cumulative incidence figures suggest at worst a small amount of overdiagnosis. FUNDING National Institute for Health Research Health Technology Assessment programme and the American Cancer Society. Past funding was received from the Medical Research Council, Cancer Research UK, the UK Department of Health, and the US National Cancer Institute. |
11884292 | BACKGROUND AND AIMS We adopted the twin method to disentangle the genetic and environmental components of susceptibility to coeliac disease (CD). We estimated disease concordance rate by zygosity and HLA genotypes, discordance times, progression rates to disease, and heritability. METHODS We crosslinked the Italian Twin Registry with the membership lists of the Italian Coeliac Disease Association and recruited 23 monozygotic (MZ) and 50 dizygotic (DZ) twin pairs with at least one affected member. Zygosity was assigned by DNA fingerprinting, and HLA-DQ and DR alleles were genotyped. Disease status was ascertained by antiendomysial, anti-human tissue transglutaminase antibodies, and bowel biopsy. RESULTS Concordance was significantly higher in MZ (83.3% probandwise, 71.4% pairwise) than in DZ (16.7% probandwise, 9.1% pairwise) pairs. Concordance was not affected by sex or HLA genotype of the co-twin and being MZ was significantly associated with the occurrence of CD (Cox adjusted hazard ratio 14.3 (95% confidence interval 4.0-50.3)). In 90% of concordant pairs the discordance time was <or=2 years. MZ and DZ co-twins had 70% and 9% cumulative probability of having symptomatic or silent forms of CD, respectively, within five years. Under ACE (additive genetic, common, and unshared environmental factors) models, with CD population prevalences of 1/91 and 1/1000, heritability estimates were 87% and 57%, respectively. CONCLUSION MZ pairs have a high probability of being concordant, regardless of sex or HLA genotype. Most of the affected co-twins receive a diagnosis within two years. A remarkable proportion of phenotypic variance is due to genetic factors. |
11886686 | The importance of neuropeptides in the hypothalamus has been experimentally established. Due to difficulties in assessing function in vivo, the roles of the fast-acting neurotransmitters glutamate and GABA are largely unknown. Synaptic vesicular transporters (VGLUTs for glutamate and VGAT for GABA) are required for vesicular uptake and, consequently, synaptic release of neurotransmitters. Ventromedial hypothalamic (VMH) neurons are predominantly glutamatergic and express VGLUT2. To evaluate the role of glutamate release from VMH neurons, we generated mice lacking VGLUT2 selectively in SF1 neurons (a major subset of VMH neurons). These mice have hypoglycemia during fasting secondary to impaired fasting-induced increases in the glucose-raising pancreatic hormone glucagon and impaired induction in liver of mRNAs encoding PGC-1alpha and the gluconeogenic enzymes PEPCK and G6Pase. Similarly, these mice have defective counterregulatory responses to insulin-induced hypoglycemia and 2-deoxyglucose (an antimetabolite). Thus, glutamate release from VMH neurons is an important component of the neurocircuitry that functions to prevent hypoglycemia. |
11887584 | The proto-oncogene c-src is rarely mutated in human cancers, and when overexpressed in normal cells is non- or weakly oncogenic. These observations have raised doubts about the involvement of c-src in the etiology of human tumors. However, recent studies have shown that c-Src, a non-receptor tyrosine kinase, exhibits elevated protein levels and activity in numerous types of human cancers. Furthermore, it has been found to be a critical component of multiple signaling pathways that regulate proliferation, survival, metastasis, and angiogenesis. Because of its important role in these oncogenic processes, it represents a therapeutic target ripe for exploitation. |
11899391 | Numerous reports have demonstrated that CD4(+)CD25(+) regulatory T cells (Tregs) from individuals with a range of human autoimmune diseases, including type 1 diabetes, are deficient in their ability to control autologous proinflammatory responses when compared with nondiseased, control individuals. Treg dysfunction could be a primary, causal event or may result from perturbations in the immune system during disease development. Polymorphisms in genes associated with Treg function, such as IL2RA, confer a higher risk of autoimmune disease. Although this suggests a primary role for defective Tregs in autoimmunity, a link between IL2RA gene polymorphisms and Treg function has not been examined. We addressed this by examining the impact of an IL2RA haplotype associated with type 1 diabetes on Treg fitness and suppressive function. Studies were conducted using healthy human subjects to avoid any confounding effects of disease. We demonstrated that the presence of an autoimmune disease-associated IL2RA haplotype correlates with diminished IL-2 responsiveness in Ag-experienced CD4(+) T cells, as measured by phosphorylation of STAT5a, and is associated with lower levels of FOXP3 expression by Tregs and a reduction in their ability to suppress proliferation of autologous effector T cells. These data offer a rationale that contributes to the molecular and cellular mechanisms through which polymorphisms in the IL-2RA gene affect immune regulation, and consequently upon susceptibility to autoimmune and inflammatory diseases. |
11902109 | The Drosophila lymph gland is a haematopoietic organ in which progenitor cells, which are most akin to the common myeloid progenitor in mammals, proliferate and differentiate into three types of mature cell--plasmatocytes, crystal cells and lamellocytes--the functions of which are reminiscent of mammalian myeloid cells. During the first and early second instars of larval development, the lymph gland contains only progenitors, whereas in the third instar, a medial region of the primary lobe of the lymph gland called the medullary zone contains these progenitors, and maturing blood cells are found juxtaposed in a peripheral region designated the cortical zone. A third group of cells referred to as the posterior signalling centre functions as a haematopoietic niche. Similarly to mammalian myeloid cells, Drosophila blood cells respond to multiple stresses including hypoxia, infection and oxidative stress. However, how systemic signals are sensed by myeloid progenitors to regulate cell-fate determination has not been well described. Here, we show that the haematopoietic progenitors of Drosophila are direct targets of systemic (insulin) and nutritional (essential amino acid) signals, and that these systemic signals maintain the progenitors by promoting Wingless (WNT in mammals) signalling. We expect that this study will promote investigation of such possible direct signal sensing mechanisms by mammalian myeloid progenitors. |
11913139 | To appreciate the neural underpinnings of sleep, it is important to view this universal mammalian behaviour at multiple levels of its biological organization. Molecularly, the circadian rhythm of sleep involves interlocking positive- and negative-feedback mechanisms of circadian genes and their protein products in cells of the suprachiasmatic nucleus that are entrained to ambient conditions by light. Circadian information is integrated with information on homeostatic sleep need in nuclei of the anterior hypothalamus. These nuclei interact with arousal systems in the posterior hypothalamus, basal forebrain and brainstem to control sleep onset. During sleep, an ultradian oscillator in the mesopontine junction controls the regular alternation of rapid eye movement (REM) and non-REM sleep. Sleep cycles are accompanied by neuromodulatory influences on forebrain structures that influence behaviour, consciousness and cognition. |
11915280 | Aberrant gene silencing accompanied by DNA methylation is associated with neoplastic progression in many tumors that also show global loss of DNA methylation. Using conditional inactivation of de novo methyltransferase Dnmt3b in Apc(Min/+) mice, we demonstrate that the loss of Dnmt3b has no impact on microadenoma formation, which is considered the earliest stage of intestinal tumor formation. Nevertheless, we observed a significant decrease in the formation of macroscopic colonic adenomas. Interestingly, many large adenomas showed regions with Dnmt3b inactivation, indicating that Dnmt3b is required for initial outgrowth of macroscopic adenomas but is not required for their maintenance. These results support a role for Dnmt3b in the transition stage between microadenoma formation and macroscopic colonic tumor growth and further suggest that Dnmt3b, and by extension de novo methylation, is not required for maintaining tumor growth after this transition stage has occurred. |
11922370 | Many of the factors required for chromosomal DNA replication have been identified in unicellular eukaryotes. However, DNA replication is poorly understood in multicellular organisms. Here, we report the identification of GEMC1 (geminin coiled-coil containing protein 1), a novel vertebrate protein required for chromosomal DNA replication. GEMC1 is highly conserved in vertebrates and is preferentially expressed in proliferating cells. Using Xenopus laevis egg extract we show that Xenopus GEMC1 (xGEMC1) binds to the checkpoint and replication factor TopBP1, which promotes binding of xGEMC1 to chromatin during pre-replication complex (pre-RC) formation. We demonstrate that xGEMC1 interacts directly with replication factors such as Cdc45 and the kinase Cdk2-CyclinE, through which it is heavily phosphorylated. Phosphorylated xGEMC1 stimulates initiation of DNA replication, whereas depletion of xGEMC1 prevents the onset of DNA replication owing to the impairment of Cdc45 loading onto chromatin. Similarly, inhibition of GEMC1 expression with morpholino and siRNA oligos prevents DNA replication in embryonic and somatic vertebrate cells. These data suggest that GEMC1 promotes initiation of chromosomal DNA replication in multicellular organisms by mediating TopBP1- and Cdk2-dependent recruitment of Cdc45 onto replication origins. |
11951999 | Ten-Eleven Translocation-2 (TET2) inactivation through loss-of-function mutation, deletion and IDH1/2 (Isocitrate Dehydrogenase 1 and 2) gene mutation is a common event in myeloid and lymphoid malignancies. TET2 gene mutations similar to those observed in myeloid and lymphoid malignancies also accumulate with age in otherwise healthy subjects with clonal hematopoiesis. TET2 is one of the three proteins of the TET (Ten-Eleven Translocation) family, which are evolutionarily conserved dioxygenases that catalyze the conversion of 5-methyl-cytosine (5-mC) to 5-hydroxymethyl-cytosine (5-hmC) and promote DNA demethylation. TET dioxygenases require 2-oxoglutarate, oxygen and Fe(II) for their activity, which is enhanced in the presence of ascorbic acid. TET2 is the most expressed TET gene in the hematopoietic tissue, especially in hematopoietic stem cells. In addition to their hydroxylase activity, TET proteins recruit the O-linked β-D-N-acetylglucosamine (O-GlcNAc) transferase (OGT) enzyme to chromatin, which promotes post-transcriptional modifications of histones and facilitates gene expression. The TET2 level is regulated by interaction with IDAX, originating from TET2 gene fission during evolution, and by the microRNA miR-22. TET2 has pleiotropic roles during hematopoiesis, including stem-cell self-renewal, lineage commitment and terminal differentiation of monocytes. Analysis of Tet2 knockout mice, which are viable and fertile, demonstrated that Tet2 functions as a tumor suppressor whose haploinsufficiency initiates myeloid and lymphoid transformations. This review summarizes the recently identified TET2 physiological and pathological functions and discusses how this knowledge influences our therapeutic approaches in hematological malignancies and possibly other tumor types. |
11968641 | BACKGROUND Circadian clocks control cell cycle factors, and circadian disruption promotes cancer. To address whether enhancing circadian rhythmicity in tumor cells affects cell cycle progression and reduces proliferation, we compared growth and cell cycle events of B16 melanoma cells and tumors with either a functional or dysfunctional clock. RESULTS We found that clock genes were suppressed in B16 cells and tumors, but treatments inducing circadian rhythmicity, such as dexamethasone, forskolin and heat shock, triggered rhythmic clock and cell cycle gene expression, which resulted in fewer cells in S phase and more in G1 phase. Accordingly, B16 proliferation in vitro and tumor growth in vivo was slowed down. Similar effects were observed in human colon carcinoma HCT-116 cells. Notably, the effects of dexamethasone were not due to an increase in apoptosis nor to an enhancement of immune cell recruitment to the tumor. Knocking down the essential clock gene Bmal1 in B16 tumors prevented the effects of dexamethasone on tumor growth and cell cycle events. CONCLUSIONS Here we demonstrated that the effects of dexamethasone on cell cycle and tumor growth are mediated by the tumor-intrinsic circadian clock. Thus, our work reveals that enhancing circadian clock function might represent a novel strategy to control cancer progression. |
11983390 | Cytoplasmic dynein is a microtubule-based motor protein that is responsible for most intracellular retrograde transports along microtubule filaments. The motor domain of dynein contains six tandemly linked AAA (ATPases associated with diverse cellular activities) modules, with the first four containing predicted nucleotide-binding/hydrolysis sites (P1-P4). To dissect the functions of these multiple nucleotide-binding/hydrolysis sites, we expressed and purified Dictyostelium dynein motor domains in which mutations were introduced to block nucleotide binding at each of the four AAA modules, and then examined their detailed biochemical properties. The P1 mutant was trapped in a strong-binding state even in the presence of ATP and lost its motile activity. The P3 mutant also showed a high affinity for microtubules in the presence of ATP and lost most of the microtubule-activated ATPase activity, but retained microtubule sliding activity, although the sliding velocity of the mutant was more than 20-fold slower than that of the wild type. In contrast, mutation in the P2 or P4 site did not affect the apparent binding affinity of the mutant for microtubules in the presence of ATP, but reduced ATPase and microtubule sliding activities. These results indicate that ATP binding and its hydrolysis only at the P1 site are essential for the motor activities of cytoplasmic dynein, and suggest that the other nucleotide-binding/hydrolysis sites regulate the motor activities. Among them, nucleotide binding at the P3 site is not essential but is critical for microtubule-activated ATPase and motile activities of cytoplasmic dynein. |
11992632 | People with Down syndrome (DS) exhibit abnormal brain structure. Alterations affecting neurotransmission and signalling pathways that govern brain function are also evident. A large number of genes are simultaneously expressed at abnormal levels in DS; therefore, it is a challenge to determine which gene(s) contribute to specific abnormalities, and then identify the key molecular pathways involved. We generated RCAN1-TG mice to study the consequences of RCAN1 over-expression and investigate the contribution of RCAN1 to the brain phenotype of DS. RCAN1-TG mice exhibit structural brain abnormalities in those areas affected in DS. The volume and number of neurons within the hippocampus is reduced and this correlates with a defect in adult neurogenesis. The density of dendritic spines on RCAN1-TG hippocampal pyramidal neurons is also reduced. Deficits in hippocampal-dependent learning and short- and long-term memory are accompanied by a failure to maintain long-term potentiation (LTP) in hippocampal slices. In response to LTP induction, we observed diminished calcium transients and decreased phosphorylation of CaMKII and ERK1/2-proteins that are essential for the maintenance of LTP and formation of memory. Our data strongly suggest that RCAN1 plays an important role in normal brain development and function and its up-regulation likely contributes to the neural deficits associated with DS. |
12009265 | CONTEXT Many individuals take vitamins in the hopes of preventing chronic diseases such as cancer, and vitamins E and C are among the most common individual supplements. A large-scale randomized trial suggested that vitamin E may reduce risk of prostate cancer; however, few trials have been powered to address this relationship. No previous trial in men at usual risk has examined vitamin C alone in the prevention of cancer. OBJECTIVE To evaluate whether long-term vitamin E or C supplementation decreases risk of prostate and total cancer events among men. DESIGN, SETTING, AND PARTICIPANTS The Physicians' Health Study II is a randomized, double-blind, placebo-controlled factorial trial of vitamins E and C that began in 1997 and continued until its scheduled completion on August 31, 2007. A total of 14,641 male physicians in the United States initially aged 50 years or older, including 1307 men with a history of prior cancer at randomization, were enrolled. INTERVENTION Individual supplements of 400 IU of vitamin E every other day and 500 mg of vitamin C daily. MAIN OUTCOME MEASURES Prostate and total cancer. RESULTS During a mean follow-up of 8.0 years, there were 1008 confirmed incident cases of prostate cancer and 1943 total cancers. Compared with placebo, vitamin E had no effect on the incidence of prostate cancer (active and placebo vitamin E groups, 9.1 and 9.5 events per 1000 person-years; hazard ratio [HR], 0.97; 95% confidence interval [CI], 0.85-1.09; P = .58) or total cancer (active and placebo vitamin E groups, 17.8 and 17.3 cases per 1000 person-years; HR, 1.04; 95% CI, 0.95-1.13; P = .41). There was also no significant effect of vitamin C on total cancer (active and placebo vitamin C groups, 17.6 and 17.5 events per 1000 person-years; HR, 1.01; 95% CI, 0.92-1.10; P = .86) or prostate cancer (active and placebo vitamin C groups, 9.4 and 9.2 cases per 1000 person-years; HR, 1.02; 95% CI, 0.90-1.15; P = .80). Neither vitamin E nor vitamin C had a significant effect on colorectal, lung, or other site-specific cancers. Adjustment for adherence and exclusion of the first 4 or 6 years of follow-up did not alter the results. Stratification by various cancer risk factors demonstrated no significant modification of the effect of vitamin E on prostate cancer risk or either agent on total cancer risk. CONCLUSIONS In this large, long-term trial of male physicians, neither vitamin E nor C supplementation reduced the risk of prostate or total cancer. These data provide no support for the use of these supplements for the prevention of cancer in middle-aged and older men. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00270647. |
12030318 | Morphogenesis and pattern formation are vital processes in any organism, whether unicellular or multicellular. But in contrast to the developmental biology of plants and animals, the principles of morphogenesis and pattern formation in single cells remain largely unknown. Although all cells develop patterns, they are most obvious in ciliates; hence, we have turned to a classical unicellular model system, the giant ciliate Stentor coeruleus. Here we show that the RNA interference (RNAi) machinery is conserved in Stentor. Using RNAi, we identify the kinase coactivator Mob1--with conserved functions in cell division and morphogenesis from plants to humans-as an asymmetrically localized patterning protein required for global patterning during development and regeneration in Stentor. Our studies reopen the door for Stentor as a model regeneration system. |
12030735 | OBJECTIVE Limited information is available about the metabolic syndrome in Asians. Furthermore, the definition of central obesity using waist circumference may not be appropriate for Asians. The objectives of this study were to determine the optimal waist circumference for diagnosing central obesity in Asians and to estimate the prevalence of the metabolic syndrome in an Asian population. RESEARCH DESIGN AND METHODS We used data from the 1998 Singapore National Health Survey, a cross-sectional survey involving 4,723 men and women of Chinese, Malay, and Asian-Indian ethnicity aged 18-69 years. Receiver operating characteristic analysis suggested that waist circumference >80 cm in women and >90 cm in men was a more appropriate definition of central obesity in this population. The prevalence of the metabolic syndrome was then determined using the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) criteria with and without the modified waist circumference criteria. RESULTS In Asians, decreasing waist circumference increased the crude prevalence of the metabolic syndrome from 12.2 to 17.9%. Using the modified Asian criteria, the prevalence of the metabolic syndrome increased from 2.9% in those aged 18-30 years to 31.0% in those aged 60-69 years. It was more common in men (prevalence 20.9% in men versus 15.5% in women; P < 0.001) and Asian Indians (prevalence 28.8% in Asian-Indians, 24.2% in Malays, and 14.8% in Chinese; P < 0.001). CONCLUSIONS NCEP ATP III criteria, applied to an Asian population, will underestimate the population at risk. With a lower waist circumference cutoff, the prevalence of the metabolic syndrome is comparable to that in Western populations. Ethnic differences are likely to exist between populations across Asia. |
12058271 | The bone marrow is the primary site for neutrophil production and release into the circulation. Because the CXC chemokine receptor-4/stromal derived factor-1 (CXCR4/SDF-1) axis plays a central role in the interactions of hematopoietic stem cells, lymphocytes, and developing neutrophils in the marrow, we investigated whether reciprocal CXCR4-dependent mechanisms might be involved in neutrophil release and subsequent return to the marrow following circulation. Neutralizing antibody to CXCR4 reduced marrow retention of infused neutrophils (45.7% +/- 0.5% to 6.9% +/- 0.5%) and was found to mobilize neutrophils from marrow (34.4% +/- 4.4%). Neutrophil CXCR4 expression and SDF-1-induced calcium flux decreased with maturation and activation of the cells, corresponding to the decreased marrow homing associated with these characteristics in vivo. Infusion of the inflammatory mediator and CXCR2 ligand KC led to mobilization of neutrophils from marrow by itself and was augmented 3-fold by low doses of CXCR4-blocking antibody that otherwise had no mobilizing effect. Examination of KC and SDF-1 calcium signaling demonstrated that the effect of KC may, in part, be due to heterologous desensitization to SDF-1. These results suggest that the CXCR4/SDF-1 axis is critical in circulating neutrophil homeostasis and that it may participate in the rapid release of neutrophils from the marrow during inflammation through a novel interaction with inflammatory CXC chemokines. |
12087063 | This study investigated whether there are race differences in the structure of informal caregiving networks. Data on 3,793 functionally impaired persons age 65 and over from the 1989 National Long-Term Care Survey were analyzed. The size of the total caregiver network and the unpaid network did not differ by race, but the likelihood of there being a non-immediate family member among unpaid caregivers was higher among disabled older blacks. These findings raise questions about whether race differences in nursing home utilization and paid long-term care services, documented in other studies, can be explained by differences in caregiving arrangements. |
12102963 | Objective: To assess the association of dietary flavonol intake with the subsequent risk of coronary heart disease (CHD) mortality. Design: Meta-analysis of prospective cohort studies published before September 2001. Studies were identified by MEDLINE and EMBASE searches and by scanning relevant reference lists. The following information was extracted from published reports: size of cohort, mean age, mean duration of follow-up, number of fatal CHD events, mean flavonol intake, main sources of flavonol intake, degree of adjustment for potential confounders, and the relation of CHD mortality to dietary flavonol intake measured at baseline. Results: Seven prospective cohorts of men and women were identified including a total of 2087 fatal CHD events. Comparison of individuals in the top third with those in the bottom third of dietary flavonol intake yielded a combined risk ratio of 0.80 (95% CI 0.69–0.93) after adjustment for known CHD risk factors and other dietary components. Conclusion: This overview of prospective cohort studies indicates that high dietary intake of flavonols from a small number of fruits and vegetables, tea and red wine may be associated with a reduced risk from CHD mortality in free-living populations. Sponsorship: Institute for International Health, University of Sydney. |
12122482 | We compared the diagnostic capabilities of MRI to CT, evoked potentials (EP), and CSF oligoclonal banding analysis in a prospective evaluation of 200 patients with suspected multiple sclerosis (MS). MRI was the best method for demonstrating dissemination in space. An abnormal appropriate EP in monosymptomatic disease was usually supported by MRI and CSF analysis as being predictive of MS as a clinical diagnosis. A normal appropriate EP study was not satisfactory because MRI and CSF analysis often did not support a diagnosis of non-MS. When there is agreement between three of these paraclinical studies, the diagnosis of MS is probably unequivocal. For use in research studies, laboratory-supported definite MS (LSDMS) could be diagnosed in 85 patients of the total 200 (42.5%), in 19/38 (50%) of optic neuritis (ON) patients, and in 24/52 (46%) of chronic progressive myelopathy (CPM) patients. MRI was 100% successful in identifying patients who qualified for LSDMS in the ON and CPM groups. In a short follow-up (less than 1 year), 19/200 (10%) went on to develop clinically definite MS (CDMS), and MRI predicted that diagnosis in 18/19 (95%). Only long-term follow-up will show how well these studies and the category of LSDMS predict the development of CDMS. The clinical diagnosis of MS (CDMS), even though only 95% accurate, must remain the gold standard. |
12130067 | Formation of the hematopoietic stem cell (HSC) niche in bone marrow (BM) is tightly associated with endochondral ossification, but little is known about the mechanisms involved. We used the oc/oc mouse, a mouse model with impaired endochondral ossification caused by a loss of osteoclast (OCL) activity, to investigate the role of osteoblasts (OBLs) and OCLs in the HSC niche formation. The absence of OCL activity resulted in a defective HSC niche associated with an increased proportion of mesenchymal progenitors but reduced osteoblastic differentiation, leading to impaired HSC homing to the BM. Restoration of OCL activity reversed the defect in HSC niche formation. Our data demonstrate that OBLs are required for establishing HSC niches and that osteoblastic development is induced by OCLs. These findings broaden our knowledge of the HSC niche formation, which is critical for understanding normal and pathological hematopoiesis. |
12130690 | Protease-activated receptor-2 (PAR-2) is a G-protein-coupled receptor activated through proteolytic cleavage. It is localized on epithelial, endothelial and inflammatory cells, as well as on transient receptor potential vanilloid 1 (TRPV1) receptor-expressing neurones. It plays an important role in inflammatory/nociceptive processes. Since there are few reports concerning PAR-2 function in joints, the effects of intraarticular PAR-2 activation on joint pain and inflammation were studied. Secondary hyperalgesia/allodynia, spontaneous weight distribution, swelling and inflammatory cytokine production were measured and the involvement of TRPV1 ion channels was investigated in rats and mice. Injection of the PAR-2 receptor agonist SLIGRL-NH(2) into the knee decreased touch sensitivity and weight bearing of the ipsilateral hindlimb in both species. Secondary mechanical allodynia/hyperalgesia and impaired weight distribution were significantly reduced by the TRPV1 antagonist SB366791 in rats and by the genetic deletion of this receptor in mice. PAR-2 activation did not cause significant joint swelling, but increased IL-1beta concentration which was not influenced by the lack of the TRPV1 channel. For comparison, intraplantar SLIGRL-NH(2) evoked similar primary mechanical hyperalgesia and impaired weight distribution in both WT and TRPV1 deficient mice, but oedema was smaller in the knockouts. The inactive peptide, LRGILS-NH(2), injected into either site did not induce any inflammatory or nociceptive changes. These data provide evidence for a significant role of TRPV1 receptors in secondary mechanical hyperalgesia/allodynia and spontaneous pain induced by PAR-2 receptor activation in the knee joint. Although intraplantar PAR-2 activation-induced oedema is also TRPV1 receptor-mediated, primary mechanical hyperalgesia, impaired weight distribution and IL-1beta production are independent of this channel. |
12156187 | The mechanism of activation of the alternative lengthening of telomeres (ALT) pathway of mammalian chromosome-end maintenance has been unclear. We have now discovered that co-depletion of the histone chaperones ASF1a and ASF1b in human cells induced all hallmarks of ALT in both primary and cancer cells. These included the formation of ALT-associated PML (promyelocytic leukemia) bodies (APBs), the presence of extrachromosomal telomeric DNA species, an elevated frequency of telomeric sister chromatid exchanges (t-SCE) events and intertelomeric exchange of an integrated tag. The induction of ALT characteristics in this setting led to the simultaneous suppression of telomerase. We determined that ALT induction is positively regulated by the proteins RAD17 and BLM and negatively regulated by EXO1 and DNA2. The induction of ALT phenotypes as a consequence of ASF1 depletion strongly supports the hypothesis that ALT is a consequence of histone management dysfunction. |
12172346 | Lysine acetylation is a key mechanism that regulates chromatin structure; aberrant acetylation levels have been linked to the development of several diseases. Acetyl-lysine modifications create docking sites for bromodomains, which are small interaction modules found on diverse proteins, some of which have a key role in the acetylation-dependent assembly of transcriptional regulator complexes. These complexes can then initiate transcriptional programmes that result in phenotypic changes. The recent discovery of potent and highly specific inhibitors for the BET (bromodomain and extra-terminal) family of bromodomains has stimulated intensive research activity in diverse therapeutic areas, particularly in oncology, where BET proteins regulate the expression of key oncogenes and anti-apoptotic proteins. In addition, targeting BET bromodomains could hold potential for the treatment of inflammation and viral infection. Here, we highlight recent progress in the development of bromodomain inhibitors, and their potential applications in drug discovery. |
12205576 | OBJECTIVE The aim was to describe the sex and socioeconomic differences in patterns of physical activity at work and in leisure time of men and women aged 36 years, and to investigate factors in childhood and adolescence which predict high rates of participation in sports and recreational activities in later life. DESIGN Data collected in childhood, adolescence, and at 36 years on members of a national prospective birth cohort study were used. SETTING The population sample was resident in England, Scotland, and Wales. SUBJECTS A stratified sample of about 3500 men and women was studied regularly from birth until 43 years. MEASUREMENTS AND MAIN RESULTS More men than women reported high rates of sports and recreational activities, gardening, and do-it-yourself. In contrast women reported higher rates of bicycling and walking. Higher levels of education were associated with frequent participation in sports. Individuals often engaged in one type of activity without necessarily engaging in other types. Those who were most active in sport had been above average at sports in school, more outgoing socially in adolescence, had fewer health problems in childhood, were better educated, and had more mothers with a secondary education than those who were less active. CONCLUSIONS Studies that examine the relationship between physical activity and chronic disease should consider a broad range of pursuits rather than extrapolating from only one area of physical activity, and in their explanations should take account of the possible role of childhood characteristics. The findings suggest the importance of developing skills and habits in childhood as well as of encouraging healthier exercise habits in adults who may have had few opportunities or low motivation previously. |
12206390 | CONTEXT The long-term risk for developing hypertension is best described by the lifetime risk statistic. The lifetime risk for hypertension and trends in this risk over time are unknown. OBJECTIVES To estimate the residual lifetime risk for hypertension in older US adults and to evaluate temporal trends in this risk. DESIGN, SETTING, AND PARTICIPANTS Community-based prospective cohort study of 1298 participants from the Framingham Heart Study who were aged 55 to 65 years and free of hypertension at baseline (1976-1998). MAIN OUTCOME MEASURES Residual lifetime risk (lifetime cumulative incidence not adjusted for competing causes of mortality) for hypertension, defined as blood pressure of 140/90 mm Hg or greater or use of antihypertensive medications. RESULTS The residual lifetime risks for developing hypertension and stage 1 high blood pressure or higher (greater-than-or-equal to 140/90 mm Hg regardless of treatment) were 90% in both 55- and 65-year-old participants. The lifetime probability of receiving antihypertensive medication was 60%. The risk for hypertension remained unchanged for women, but it was approximately 60% higher for men in the contemporary 1976-1998 period compared with an earlier 1952-1975 period. In contrast, the residual lifetime risk for stage 2 high blood pressure or higher (greater-than-or-equal to 160/100 mm Hg regardless of treatment) was considerably lower in both sexes in the recent period (35%-57% in 1952-1975 vs 35%-44% in 1976-1998), likely due to a marked increase in treatment of individuals with substantially elevated blood pressure. CONCLUSION The residual lifetime risk for hypertension for middle-aged and elderly individuals is 90%, indicating a huge public health burden. Although the decline in lifetime risk for stage 2 high blood pressure or higher represents a major achievement, efforts should be directed at the primary prevention of hypertension. |
12207167 | PHENYLALANINE TOXICITY 158 Developing the 0. -M ethylphenylalanine Model. . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160 Use of the a-Methyl phenylalanine Model in Brain Protein Synthesis . . . . . . . . . . . . . . . . . . . 161 TYROSINE TOXICITY 162 General Nutritional Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162 Factors Affecting Tissue Concentrations of Tyrosine . ... .. .. .. ...... . . . . . . .. . . 163 Probable Cause of Tyrosine Toxicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164 A New Animal Model for Human Tyrosinemia II 165 TRYPTOPHAN TOXICITy 165 General Nutritional Observations . .. ....... . ....... . .... . . .. . . . .. . .. . .. ..... ......... 165 Factors Affecting Tryptophan Toxicity . . . .. . . . . . . . .... . ........ 166 Tryptophan and Ruminant Interstitial Pulmonary Emphysema and Edema ..... . . . . . . . 167 HISTIDINE TOXICITY 168 General Nutritional Observations ...... ........ . . . . ..... . ...... .. . 168 Metabolic Aspects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 Alleviation of Histidine Toxicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170 METHIONINE TOXICITY 171 General Nutritional Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 Tissue Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . 172 Protective Effect of Glycine, Serine, or Retinol . . . .. ....... . ......... . ......... .. . .. . . ...... 172 Chemical Characteristics Related to the Toxicity of Methionine . . . . . . . . . . . . . . . . . . . . . . . . . 173 Damaging Effects of Methanethiol. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . 173 Met�io,!ine To�i.city in Chickens 174 EthlOnme TOxIcIty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . ... . 174 |
12207340 | The repair of DNA double-strand breaks (DSBs) by homologous recombination (HR) is initiated by nucleolytic degradation of the 5'-terminated strands in a process termed end resection. End resection generates 3'-single-stranded DNA tails, substrates for Rad51 to catalyze homologous pairing and DNA strand exchange, and for activation of the DNA damage checkpoint. The commonly accepted view is that end resection occurs by a two-step mechanism. In the first step, Sae2/CtIP activates the Mre11-Rad50-Xrs2/Nbs1 (MRX/N) complex to endonucleolytically cleave the 5'-terminated DNA strands close to break ends, and in the second step Exo1 and/or Dna2 nucleases extend the resected tracts to produce long 3'-ssDNA-tailed intermediates. Initiation of resection commits a cell to repair a DSB by HR because long ssDNA overhangs are poor substrates for non-homologous end joining (NHEJ). Thus, the initiation of end resection has emerged as a critical control point for repair pathway choice. Here, I review recent studies on the mechanism of end resection and how this process is regulated to ensure the most appropriate repair outcome. |
12217662 | RAS and many other oncogenic proteins undergo a complex series of post-translational modifications that are initiated by the addition of an isoprenoid lipid through a process known as prenylation. Following prenylation, these proteins usually undergo endoproteolytic processing by the RCE1 protease and then carboxyl methylation by a unique methyltransferase known as isoprenylcysteine carboxyl methyltransferase (ICMT). Although inhibitors that have been designed to target the prenylation step are now in advanced-stage clinical trials, their utility and efficacy seem to be limited. Recent findings, however, indicate that the inhibition of these post-prenylation-processing steps — particularly that of ICMT-catalysed methylation — might provide a better approach to the control of cancer-cell proliferation. |
12225214 | Ubiquitination controls a broad range of cellular functions. The last step of the ubiquitination pathway is regulated by enzyme type 3 (E3) ubiquitin ligases. E3 enzymes are responsible for substrate specificity and catalyze the formation of an isopeptide bond between a lysine residue of the substrate (or the N terminus of the substrate) and ubiquitin. MIR1 and MIR2 are two E3 ubiquitin ligases encoded by Kaposi's sarcoma-associated herpesvirus that mediate the ubiquitination of major histocompatibility complex class I (MHC I) molecules and subsequent internalization. Here, we found that MIR1, but not MIR2, promoted down-regulation of MHC I molecules lacking lysine residues in their intracytoplasmic domain. In the presence of MIR1, these MHC I molecules were ubiquitinated, and their association with ubiquitin was sensitive to beta2-mercaptoethanol, unlike lysine-ubiquitin bonds. This form of ubiquitination required a cysteine residue in the intracytoplasmic tail of MHC I molecules. An MHC I molecule containing a single cysteine residue in an artificial glycine and alanine intracytoplasmic domain was endocytosed and degraded in the presence of MIR1. Thus, ubiquitination can occur on proteins lacking accessible lysines or an accessible N terminus. |
12236208 | Patients with inflammatory bowel disease have an increased prevalence of osteoporosis, and suffer high rates of spinal bone loss. Hormone replacement therapy (HRT) is effective in the treatment and prevention of osteoporosis but has not been studied in patients with inflammatory bowel disease. A two year prospective study of HRT in inflammatory bowel disease was performed in 47 postmenopausal women aged 44 to 67 years with ulcerative colitis (25) or Crohn's disease (22). Patients had radial and spinal bone density measured annually by single photon absorptiometry and quantitative computed tomography respectively. The mean (95% confidence intervals) annual change in radial bone density was +1.42%/yr (+0.58 to +2.26; P < 0.005) and for spinal bone +2.60%/yr (+1.06 to +4.15; p < 0.005). There was no significant correlation between rates of change of bone density at the two sites, or between the rates of change and the initial bone density either in the radius or spine. Twelve patients were given prednisolone during the study, and their rates of change for spinal bone density were lower, but values were not statistically significantly different from those who did not receive corticosteroids. Changes in bone density for patients with ulcerative colitis and Crohn's disease were not significantly different. The change in bone density did not correlate with the patients' age or number of years after the menopause. It is concluded that HRT is effective in prevention of bone loss in postmenopausal women with inflammatory bowel disease. |
12240507 | Diamond-Blackfan anemia (DBA) is a congenital erythroid hypoplasia caused by haploinsufficiency of genes encoding ribosomal proteins (RPs). Perturbed ribosome biogenesis in DBA has been shown to induce a p53-mediated ribosomal stress response. However, the mechanisms of p53 activation and its relevance for the erythroid defect remain elusive. Previous studies have indicated that activation of p53 is caused by the inhibition of mouse double minute 2 (Mdm2), the main negative regulator of p53, by the 5S ribonucleoprotein particle (RNP). Meanwhile, it is not clear whether this mechanism solely mediates the p53-dependent component found in DBA. To approach this question, we crossed our mouse model for RPS19-deficient DBA with Mdm2C305F knock-in mice that have a disrupted 5S RNP–Mdm2 interaction. Upon induction of the Rps19 deficiency, Mdm2C305F reversed the p53 response and improved expansion of hematopoietic progenitors in vitro, and ameliorated the anemia in vivo. Unexpectedly, disruption of the 5S RNP–Mdm2 interaction also led to selective defect in erythropoiesis. Our findings highlight the sensitivity of erythroid progenitor cells to aberrations in p53 homeostasis mediated by the 5S RNP–Mdm2 interaction. Finally, we provide evidence indicating that physiological activation of the 5S RNP-Mdm2-p53 pathway may contribute to functional decline of the hematopoietic system in a cell-autonomous manner over time. |
12258338 | CONTEXT Pharmacist review of medication orders in the intensive care unit (ICU) has been shown to prevent errors, and pharmacist consultation has reduced drug costs. However, whether pharmacist participation in the ICU at the time of drug prescribing reduces adverse events has not been studied. OBJECTIVE To measure the effect of pharmacist participation on medical rounds in the ICU on the rate of preventable adverse drug events (ADEs) caused by ordering errors. DESIGN Before-after comparison between phase 1 (baseline) and phase 2 (after intervention implemented) and phase 2 comparison with a control unit that did not receive the intervention. SETTING A medical ICU (study unit) and a coronary care unit (control unit) in a large urban teaching hospital. PATIENTS Seventy-five patients randomly selected from each of 3 groups: all admissions to the study unit from February 1, 1993, through July 31, 1993 (baseline) and all admissions to the study unit (postintervention) and control unit from October 1, 1994, through July 7, 1995. In addition, 50 patients were selected at random from the control unit during the baseline period. INTERVENTION A senior pharmacist made rounds with the ICU team and remained in the ICU for consultation in the morning, and was available on call throughout the day. MAIN OUTCOME MEASURES Preventable ADEs due to ordering (prescribing) errors and the number, type, and acceptance of interventions made by the pharmacist. Preventable ADEs were identified by review of medical records of the randomly selected patients during both preintervention and postintervention phases. Pharmacists recorded all recommendations, which were then analyzed by type and acceptance. RESULTS The rate of preventable ordering ADEs decreased by 66% from 10.4 per 1000 patient-days (95% confidence interval [CI], 7-14) before the intervention to 3.5 (95% CI, 1-5; P<.001) after the intervention. In the control unit, the rate was essentially unchanged during the same time periods: 10.9 (95% CI, 6-16) and 12.4 (95% CI, 8-17) per 1000 patient-days. The pharmacist made 366 recommendations related to drug ordering, of which 362 (99%) were accepted by physicians. CONCLUSIONS The presence of a pharmacist on rounds as a full member of the patient care team in a medical ICU was associated with a substantially lower rate of ADEs caused by prescribing errors. Nearly all the changes were readily accepted by physicians. |
12265561 | The conformation of the ligand in complex with a macromolecular target can be studied by nuclear magnetic resonance (NMR) in solution for both tightly and weakly forming complexes. In the weak binding regime (k(off) > 10(4) Hz), the structure of the bound ligand is accessible also for very large complexes (>100 kDa), which are not amenable to NMR studies in the tight binding regime. Here I review the state-of-the-art NMR methodology used for screening ligands and for the structural investigation of bound ligand conformations, in both tight and weak binding regimes. The advantages and disadvantages of each approach are critically described. The NMR methodology used to investigate transiently forming complexes has expanded considerably in the past few years, opening new possibilities for a detailed description of ligand-target interactions. Novel methods for the determination of the bound ligand conformation, in particular transferred cross-correlated relaxation, are thoroughly reviewed, and their advantages with respect to established methodology are discussed, using the epothilone-tubulin complex as a primary example. |
12280462 | Bile acids are recognized as metabolic modulators. The present study was aimed at evaluating the effects of a potent Asbt inhibitor (264W94), which blocks intestinal absorption of bile acids, on glucose homeostasis in Zucker Diabetic Fatty (ZDF) rats. Oral administration of 264W94 for two wk increased fecal bile acid concentrations and elevated non-fasting plasma total Glp-1. Treatment of 264W94 significantly decreased HbA1c and glucose, and prevented the drop of insulin levels typical of ZDF rats in a dose-dependent manner. An oral glucose tolerance test revealed up to two-fold increase in plasma total Glp-1 and three-fold increase in insulin in 264W94 treated ZDF rats at doses sufficient to achieve glycemic control. Tissue mRNA analysis indicated a decrease in farnesoid X receptor (Fxr) activation in small intestines and the liver but co-administration of a Fxr agonist (GW4064) did not attenuate 264W94 induced glucose lowering effects. In summary, our results demonstrate that inhibition of Asbt increases bile acids in the distal intestine, promotes Glp-1 release and may offer a new therapeutic strategy for type 2 diabetes mellitus. |
12324049 | We analyzed the DNA methylome of ten subpopulations spanning the entire B cell differentiation program by whole-genome bisulfite sequencing and high-density microarrays. We observed that non-CpG methylation disappeared upon B cell commitment, whereas CpG methylation changed extensively during B cell maturation, showing an accumulative pattern and affecting around 30% of all measured CpG sites. Early differentiation stages mainly displayed enhancer demethylation, which was associated with upregulation of key B cell transcription factors and affected multiple genes involved in B cell biology. Late differentiation stages, in contrast, showed extensive demethylation of heterochromatin and methylation gain at Polycomb-repressed areas, and genes with apparent functional impact in B cells were not affected. This signature, which has previously been linked to aging and cancer, was particularly widespread in mature cells with an extended lifespan. Comparing B cell neoplasms with their normal counterparts, we determined that they frequently acquire methylation changes in regions already undergoing dynamic methylation during normal B cell differentiation. |
12358173 | Angiogenesis is a recently described prognostic factor in non-small-cell lung cancer. Platelet-derived endothelial cell growth factor (PD-ECGF), shown to be the enzyme thymidine phosphorylase (TP), induces angiogenesis in vitro and in vivo. High intracellular levels of the enzyme are associated with increased chemosensitivity to pyrimidine antimetabolites. PD-ECGF/TP expression was evaluated immunohistochemically in surgically resected specimens from 107 patients with operable non-small-cell lung cancer using the P-GF,44C monoclonal antibody. High expression of PD-ECGF/TP was found in 25% of cases and was associated with high vascular grade (P = 0.01). Fourteen of 32 (44%) high vascular grade tumours showed a positive reactivity for PD-ECGF/TP vs 13/75 (17%) of low/medium vascular grade. Positive expression was observed more frequently in T2-staged cases than in T1 (P = 0.04). While overall survival was not affected (P = 0.09), subset analysis revealed that node-negative patients with positive PD-ECGF/TP expression had a worse prognosis (P = 0.04). The results suggest that PD-ECGF/TP may be an important molecule involved in angiogenesis in non-small-cell lung cancer. Up-regulation of the enzyme defines a more aggressive tumour phenotype in patients with node-negative disease. Assessment of vascular grade and PD-ECGF/TP expression should be taken into account in the design of randomized trials assessing the role of adjuvant chemotherapy in non-small-cell lung cancer. |
12409683 | BACKGROUND Artemisinin combination therapies (ACT), which are increasingly being introduced for treatment of Plasmodium falciparum malaria, are more effective against sexual stage parasites (gametocytes) than previous first-line antimalarials and therefore have the potential to reduce parasite transmission. The size of this effect is estimated in symptomatic P. falciparum infections. METHODS Data on 3,174 patients were pooled from six antimalarial trials conducted in The Gambia and Kenya. Multivariable regression was used to investigate the role of ACT versus non-artemisinin antimalarial treatment, treatment failure, presence of pre-treatment gametocytes and submicroscopic gametocytaemia on transmission to mosquitoes and the area under the curve (AUC) of gametocyte density during the 28 days of follow up. RESULTS ACT treatment was associated with a significant reduction in the probability of being gametocytaemic on the day of transmission experiments (OR 0.20 95% CI 0.16-0.26), transmission to mosquitoes by slide-positive gametocyte carriers (OR mosquito infection 0.49 95% CI 0.33-0.73) and AUC of gametocyte density (ratio of means 0.35 95% CI 0.31-0.41). Parasitological treatment failure did not account for the difference between ACT and non-artemisinin impact. The presence of slide-positive gametocytaemia prior to treatment significantly reduced ACT impact on gametocytaemia (p < 0.001). Taking account of submicroscopic gametocytaemia reduced estimates of ACT impact in a high transmission setting in Kenya, but not in a lower transmission setting in the Gambia. CONCLUSION Treatment with ACT significantly reduces infectiousness of individual patients with uncomplicated falciparum malaria compared to previous first line treatments. Rapid treatment of cases before gametocytaemia is well developed may enhance the impact of ACT on transmission. |
12411274 | Skeletal muscle in vertebrates is derived from somites, epithelial structures of the paraxial mesoderm, yet many unrelated reports describe the occasional appearance of myogenic cells from tissues of nonsomite origin, suggesting either transdifferentiation or the persistence of a multipotent progenitor. Here, we show that clonable skeletal myogenic cells are present in the embryonic dorsal aorta of mouse embryos. This finding is based on a detailed clonal analysis of different tissue anlagen at various developmental stages. In vitro, these myogenic cells show the same morphology as satellite cells derived from adult skeletal muscle, and express a number of myogenic and endothelial markers. Surprisingly, the latter are also expressed by adult satellite cells. Furthermore, it is possible to clone myogenic cells from limbs of mutant c-Met-/- embryos, which lack appendicular muscles, but have a normal vascular system. Upon transplantation, aorta-derived myogenic cells participate in postnatal muscle growth and regeneration, and fuse with resident satellite cells. The potential of the vascular system to generate skeletal muscle cells may explain observations of nonsomite skeletal myogenesis and raises the possibility that a subset of satellite cells may derive from the vascular system. |
12428497 | BACKGROUND Adoption of new and underutilized vaccines by national immunization programs is an essential step towards reducing child mortality. Policy decisions to adopt new vaccines in high mortality countries often lag behind decisions in high-income countries. Using the case of Haemophilus influenzae type b (Hib) vaccine, this paper endeavors to explain these delays through the analysis of country-level economic, epidemiological, programmatic and policy-related factors, as well as the role of the Global Alliance for Vaccines and Immunisation (GAVI Alliance). METHODS AND FINDINGS Data for 147 countries from 1990 to 2007 were analyzed in accelerated failure time models to identify factors that are associated with the time to decision to adopt Hib vaccine. In multivariable models that control for Gross National Income, region, and burden of Hib disease, the receipt of GAVI support speeded the time to decision by a factor of 0.37 (95% CI 0.18-0.76), or 63%. The presence of two or more neighboring country adopters accelerated decisions to adopt by a factor of 0.50 (95% CI 0.33-0.75). For each 1% increase in vaccine price, decisions to adopt are delayed by a factor of 1.02 (95% CI 1.00-1.04). Global recommendations and local studies were not associated with time to decision. CONCLUSIONS This study substantiates previous findings related to vaccine price and presents new evidence to suggest that GAVI eligibility is associated with accelerated decisions to adopt Hib vaccine. The influence of neighboring country decisions was also highly significant, suggesting that approaches to support the adoption of new vaccines should consider supply- and demand-side factors. |
12438901 | BACKGROUND For women with oestrogen receptor (ER)-positive early breast cancer, treatment with tamoxifen for 5 years substantially reduces the breast cancer mortality rate throughout the first 15 years after diagnosis. We aimed to assess the further effects of continuing tamoxifen to 10 years instead of stopping at 5 years. METHODS In the worldwide Adjuvant Tamoxifen: Longer Against Shorter (ATLAS) trial, 12,894 women with early breast cancer who had completed 5 years of treatment with tamoxifen were randomly allocated to continue tamoxifen to 10 years or stop at 5 years (open control). Allocation (1:1) was by central computer, using minimisation. After entry (between 1996 and 2005), yearly follow-up forms recorded any recurrence, second cancer, hospital admission, or death. We report effects on breast cancer outcomes among the 6846 women with ER-positive disease, and side-effects among all women (with positive, negative, or unknown ER status). Long-term follow-up still continues. This study is registered, number ISRCTN19652633. FINDINGS Among women with ER-positive disease, allocation to continue tamoxifen reduced the risk of breast cancer recurrence (617 recurrences in 3428 women allocated to continue vs 711 in 3418 controls, p=0·002), reduced breast cancer mortality (331 deaths vs 397 deaths, p=0·01), and reduced overall mortality (639 deaths vs 722 deaths, p=0·01). The reductions in adverse breast cancer outcomes appeared to be less extreme before than after year 10 (recurrence rate ratio [RR] 0·90 [95% CI 0·79–1·02] during years 5–9 and 0·75 [0·62–0·90] in later years; breast cancer mortality RR 0·97 [0·79–1·18] during years 5–9 and 0·71 [0·58–0·88] in later years). The cumulative risk of recurrence during years 5–14 was 21·4% for women allocated to continue versus 25·1% for controls; breast cancer mortality during years 5–14 was 12·2% for women allocated to continue versus 15·0% for controls (absolute mortality reduction 2·8%). Treatment allocation seemed to have no effect on breast cancer outcome among 1248 women with ER-negative disease, and an intermediate effect among 4800 women with unknown ER status. Among all 12,894 women, mortality without recurrence from causes other than breast cancer was little affected (691 deaths without recurrence in 6454 women allocated to continue versus 679 deaths in 6440 controls; RR 0·99 [0·89–1·10]; p=0·84). For the incidence (hospitalisation or death) rates of specific diseases, RRs were as follows: pulmonary embolus 1·87 (95% CI 1·13–3·07, p=0·01 [including 0·2% mortality in both treatment groups]), stroke 1·06 (0·83–1·36), ischaemic heart disease 0·76 (0·60–0·95, p=0·02), and endometrial cancer 1·74 (1·30–2·34, p=0·0002). The cumulative risk of endometrial cancer during years 5–14 was 3·1% (mortality 0·4%) for women allocated to continue versus 1·6% (mortality 0·2%) for controls (absolute mortality increase 0·2%). INTERPRETATION For women with ER-positive disease, continuing tamoxifen to 10 years rather than stopping at 5 years produces a further reduction in recurrence and mortality, particularly after year 10. These results, taken together with results from previous trials of 5 years of tamoxifen treatment versus none, suggest that 10 years of tamoxifen treatment can approximately halve breast cancer mortality during the second decade after diagnosis. FUNDING Cancer Research UK, UK Medical Research Council, AstraZeneca UK, US Army, EU-Biomed. |
12440953 | Biological systems use a variety of mechanisms to maintain their functions in the face of environmental and genetic perturbations. Increasing evidence suggests that, among their roles as posttranscriptional repressors of gene expression, microRNAs (miRNAs) help to confer robustness to biological processes by reinforcing transcriptional programs and attenuating aberrant transcripts, and they may in some network contexts help suppress random fluctuations in transcript copy number. These activities have important consequences for normal development and physiology, disease, and evolution. Here, we will discuss examples and principles of miRNAs that contribute to robustness in animal systems. |
12442311 | BACKGROUND The analgesic co-proxamol (paracetamol/dextropropoxyphene combination) has been widely involved in fatal poisoning. Concerns about its safety/effectiveness profile and widespread use for suicidal poisoning prompted its withdrawal in the UK in 2005, with partial withdrawal between 2005 and 2007, and full withdrawal in 2008. Our objective in this study was to assess the association between co-proxamol withdrawal and prescribing and deaths in England and Wales in 2005-2010 compared with 1998-2004, including estimation of possible substitution effects by other analgesics. METHODS AND FINDINGS We obtained prescribing data from the NHS Health and Social Care Information Centre (England) and Prescribing Services Partneriaeth Cydwasanaethau GIG Cymru (Wales), and mortality data from the Office for National Statistics. We carried out an interrupted time-series analysis of prescribing and deaths (suicide, open verdicts, accidental poisonings) involving single analgesics. The reduction in prescribing of co-proxamol following its withdrawal in 2005 was accompanied by increases in prescribing of several other analgesics (co-codamol, paracetamol, codeine, co-dydramol, tramadol, oxycodone, and morphine) during 2005-2010 compared with 1998-2004. These changes were associated with major reductions in deaths due to poisoning with co-proxamol receiving verdicts of suicide and undetermined cause of -21 deaths (95% CI -34 to -8) per quarter, equating to approximately 500 fewer suicide deaths (-61%) over the 6 years 2005-2010, and -25 deaths (95% CI -38 to -12) per quarter, equating to 600 fewer deaths (-62%) when accidental poisoning deaths were included. There was little observed change in deaths involving other analgesics, apart from an increase in oxycodone poisonings, but numbers were small. Limitations were that the study was based on deaths involving single drugs alone and changes in deaths involving prescribed morphine could not be assessed. CONCLUSIONS During the 6 years following the withdrawal of co-proxamol in the UK, there was a major reduction in poisoning deaths involving this drug, without apparent significant increase in deaths involving other analgesics. |
12471115 | BACKGROUND The pneumococcus is a diverse pathogen whose primary niche is the nasopharynx. Over 90 different serotypes exist, and nasopharyngeal carriage of multiple serotypes is common. Understanding pneumococcal carriage is essential for evaluating the impact of pneumococcal vaccines. Traditional serotyping methods are cumbersome and insufficient for detecting multiple serotype carriage, and there are few data comparing the new methods that have been developed over the past decade. We established the PneuCarriage project, a large, international multi-centre study dedicated to the identification of the best pneumococcal serotyping methods for carriage studies. METHODS AND FINDINGS Reference sample sets were distributed to 15 research groups for blinded testing. Twenty pneumococcal serotyping methods were used to test 81 laboratory-prepared (spiked) samples. The five top-performing methods were used to test 260 nasopharyngeal (field) samples collected from children in six high-burden countries. Sensitivity and positive predictive value (PPV) were determined for the test methods and the reference method (traditional serotyping of >100 colonies from each sample). For the alternate serotyping methods, the overall sensitivity ranged from 1% to 99% (reference method 98%), and PPV from 8% to 100% (reference method 100%), when testing the spiked samples. Fifteen methods had ≥70% sensitivity to detect the dominant (major) serotype, whilst only eight methods had ≥70% sensitivity to detect minor serotypes. For the field samples, the overall sensitivity ranged from 74.2% to 95.8% (reference method 93.8%), and PPV from 82.2% to 96.4% (reference method 99.6%). The microarray had the highest sensitivity (95.8%) and high PPV (93.7%). The major limitation of this study is that not all of the available alternative serotyping methods were included. CONCLUSIONS Most methods were able to detect the dominant serotype in a sample, but many performed poorly in detecting the minor serotype populations. Microarray with a culture amplification step was the top-performing method. Results from this comprehensive evaluation will inform future vaccine evaluation and impact studies, particularly in low-income settings, where pneumococcal disease burden remains high. |
12489688 | Neutrophilic polymorphonuclear leukocytes (neutrophils) are highly specialized for their primary function, the phagocytosis and destruction of microorganisms. When coated with opsonins (generally complement and/or antibody), microorganisms bind to specific receptors on the surface of the phagocyte and invagination of the cell membrane occurs with the incorporation of the microorganism into an intracellular phagosome. There follows a burst of oxygen consumption, and much, if not all, of the extra oxygen consumed is converted to highly reactive oxygen species. In addition, the cytoplasmic granules discharge their contents into the phagosome, and death of the ingested microorganism soon follows. Among the antimicrobial systems formed in the phagosome is one consisting of myeloperoxidase (MPO), released into the phagosome during the degranulation process, hydrogen peroxide (H2O2), formed by the respiratory burst and a halide, particularly chloride. The initial product of the MPO-H2O2-chloride system is hypochlorous acid, and subsequent formation of chlorine, chloramines, hydroxyl radicals, singlet oxygen, and ozone has been proposed. These same toxic agents can be released to the outside of the cell, where they may attack normal tissue and thus contribute to the pathogenesis of disease. This review will consider the potential sources of H2O2 for the MPO-H2O2-halide system; the toxic products of the MPO system; the evidence for MPO involvement in the microbicidal activity of neutrophils; the involvement of MPO-independent antimicrobial systems; and the role of the MPO system in tissue injury. It is concluded that the MPO system plays an important role in the microbicidal activity of phagocytes. |
12513042 | The importance of prostaglandin E(2) in various pathophysiological events emphasizes the necessity of understanding the role of PGE synthases (PGESs) in vivo. However, there has been no report on the functional relevance of microsomal PGES-1 (mPGES-1) to the physiological healing processes of gastric ulcers, or to angiogenesis, which is indispensable to the healing processes. In this report, we tested whether mPGES-1 plays a role in the healing of gastric ulcers and in the enhancement of angiogenesis using mPGES-1 knockout mice (mPGES-1 KO mice) and their wild-type (WT) counterparts. Gastric ulcers were induced by the serosal application of 100% acetic acid, and the areas of the ulcers were measured thereafter. mPGES-1 together with cyclooxygenase-2 were induced in the granulation tissues compared with normal stomach tissues. The healing of acetic acid-induced ulcers was significantly delayed in mPGES-1 KO mice compared with WT. This was accompanied with reduced angiogenesis in ulcer granulation tissues, as estimated by CD31 mRNA levels determined by real-time PCR and the microvessel density in granulation tissues. The mRNA levels of proangiogenic growth factors, such as transforming growth factor-β, basic fibroblast growth factor, and connective tissue growth factor in ulcer granulation tissues determined were reduced in mPGES-1 KO mice compared with WT. The present results suggest that mPGES-1 enhances the ulcer-healing processes and the angiogenesis indispensable to ulcer healing, and that a selective mPGES-1 inhibitor should be used with care in patients with gastric ulcers. |
12552297 | DNA polymerase lambda (polλ) is a recently identified DNA polymerase whose cellular function remains elusive. Here we show, that polλ participates at the molecular level in a chromosomal context, in the repair of DNA double strand breaks (DSB) via non-homologous end joining (NHEJ) in mammalian cells. The expression of a catalytically inactive form of polλ (polλDN) decreases the frequency of NHEJ events in response to I-Sce-I-induced DSB whereas inactivated forms of its homologues polβ and polμ do not. Only events requiring DNA end processing before ligation are affected; this defect is associated with large deletions arising in the vicinity of the induced DSB. Furthermore, polλDN-expressing cells exhibit increased sensitization and genomic instability in response to ionizing radiation similar to that of NHEJ-defective cells. Our data support a requirement for polλ in repairing a subset of DSB in genomic DNA, thereby contributing to the maintenance of genetic stability mediated by the NHEJ pathway. |
12561083 | BACKGROUND Several studies have demonstrated that women with nonobstructive coronary disease have a high rate of subsequent investigations, rehospitalizations for recurrent chest pain, and repeat coronary angiography. The sex specificity of this finding is unclear. We therefore undertook an evaluation of sex differences in rehospitalization for acute coronary syndrome (ACS) or chest pain in patients with "angiographically normal" coronaries. METHODS A retrospective cohort study using prospectively collected angiographic and clinical data on all patients in British Columbia, Canada, presenting for their first cardiac catheterization with suspected ischemic heart disease but angiographically normal coronaries. RESULTS Among 32,856 patients, 7.1% of men versus 23.3% of women were angiographically normal (P < .001). Among angiographically normal patients, women were older and more likely to present with hypertension, prior stroke, chronic obstructive pulmonary disease, and peripheral vascular disease than men, but Canadian Cardiovascular Society class of angina did not vary by sex. Within 1 year, 1.0% died, (19 women, 18 men, P = .27) and 0.6% had a stroke (13 women, 9 men, P = .91). Readmission to hospital for ACS or chest pain requiring catheterization was significantly higher in women compared to men (adjusted OR 4.06; 95% CI 1.15-14.31). CONCLUSIONS In a contemporary, population-based cohort presenting for cardiac catheterization for suspected ischemia, women with angiographically normal coronaries were >4 times more likely to be readmitted to hospital for ACS/chest pain within 180 days compared to men. The observed sex difference has important social and economic implications and suggests that traditional diagnostic methods may not be optimal for women. |
12580014 | Expression of the intermediate filament protein keratin 17 (K17) is robustly upregulated in inflammatory skin diseases and in many tumors originating in stratified and pseudostratified epithelia. We report that autoimmune regulator (Aire), a transcriptional regulator, is inducibly expressed in human and mouse tumor keratinocytes in a K17-dependent manner and is required for timely onset of Gli2-induced skin tumorigenesis in mice. The induction of Aire mRNA in keratinocytes depends on a functional interaction between K17 and the heterogeneous nuclear ribonucleoprotein hnRNP K. Further, K17 colocalizes with Aire protein in the nucleus of tumor-prone keratinocytes, and each factor is bound to a specific promoter region featuring an NF-κB consensus sequence in a relevant subset of K17- and Aire-dependent proinflammatory genes. These findings provide radically new insight into keratin intermediate filament and Aire function, along with a molecular basis for the K17-dependent amplification of inflammatory and immune responses in diseased epithelia. |
12584053 | OBJECTIVE To measure whether the benefits of a single education and self management structured programme for people with newly diagnosed type 2 diabetes mellitus are sustained at three years. DESIGN Three year follow-up of a multicentre cluster randomised controlled trial in primary care, with randomisation at practice level. SETTING 207 general practices in 13 primary care sites in the United Kingdom. PARTICIPANTS 731 of the 824 participants included in the original trial were eligible for follow-up. Biomedical data were collected on 604 (82.6%) and questionnaire data on 513 (70.1%) participants. INTERVENTION A structured group education programme for six hours delivered in the community by two trained healthcare professional educators compared with usual care. MAIN OUTCOME MEASURES The primary outcome was glycated haemoglobin (HbA(1c)) levels. The secondary outcomes were blood pressure, weight, blood lipid levels, smoking status, physical activity, quality of life, beliefs about illness, depression, emotional impact of diabetes, and drug use at three years. RESULTS HbA(1c) levels at three years had decreased in both groups. After adjusting for baseline and cluster the difference was not significant (difference -0.02, 95% confidence interval -0.22 to 0.17). The groups did not differ for the other biomedical and lifestyle outcomes and drug use. The significant benefits in the intervention group across four out of five health beliefs seen at 12 months were sustained at three years (P<0.01). Depression scores and quality of life did not differ at three years. CONCLUSION A single programme for people with newly diagnosed type 2 diabetes mellitus showed no difference in biomedical or lifestyle outcomes at three years although there were sustained improvements in some illness beliefs. TRIAL REGISTRATION Current Controlled Trials ISRCTN17844016. |
12631697 | Limited neural input results in muscle weakness in neuromuscular disease because of a reduction in the density of muscle innervation, the rate of neuromuscular junction activation or the efficiency of synaptic transmission. We developed a small-molecule fast-skeletal-troponin activator, CK-2017357, as a means to increase muscle strength by amplifying the response of muscle when neural input is otherwise diminished secondary to neuromuscular disease. Binding selectively to the fast-skeletal-troponin complex, CK-2017357 slows the rate of calcium release from troponin C and sensitizes muscle to calcium. As a consequence, the force-calcium relationship of muscle fibers shifts leftwards, as does the force-frequency relationship of a nerve-muscle pair, so that CK-2017357 increases the production of muscle force in situ at sub-maximal nerve stimulation rates. Notably, we show that sensitization of the fast-skeletal-troponin complex to calcium improves muscle force and grip strength immediately after administration of single doses of CK-2017357 in a model of the neuromuscular disease myasthenia gravis. Troponin activation may provide a new therapeutic approach to improve physical activity in diseases where neuromuscular function is compromised. |
12641252 | Anthracyclin-treated tumor cells are particularly effective in eliciting an anticancer immune response, whereas other DNA-damaging agents such as etoposide and mitomycin C do not induce immunogenic cell death. Here we show that anthracyclins induce the rapid, preapoptotic translocation of calreticulin (CRT) to the cell surface. Blockade or knockdown of CRT suppressed the phagocytosis of anthracyclin-treated tumor cells by dendritic cells and abolished their immunogenicity in mice. The anthracyclin-induced CRT translocation was mimicked by inhibition of the protein phosphatase 1/GADD34 complex. Administration of recombinant CRT or inhibitors of protein phosphatase 1/GADD34 restored the immunogenicity of cell death elicited by etoposide and mitomycin C, and enhanced their antitumor effects in vivo. These data identify CRT as a key feature determining anticancer immune responses and delineate a possible strategy for immunogenic chemotherapy. |
12642224 | DNA oligonucleotide complementary to sequences in the 5' third of U3 snRNA were injected into Xenopus oocyte nuclei to disrupt endogenous U3 snRNA. The effect of this treatment on rRNA processing was examined. We found that some toads have a single rRNA processing pathway, whereas in other toads, two rRNA processing pathways can coexist in a single oocyte. U3 snRNA disruption in toads with the single rRNA processing pathway caused a reduction in 20S and '32S' pre-rRNA. In addition, in toads with two rRNA processing pathways, an increase in '36S' pre-rRNA of the second pathway is observed. This is the first in vivo demonstration that U3 snRNA plays a role in rRNA processing. Cleavage site #3 is at the boundary of ITS 1 and 5.8S and links all of the affected rRNA intermediates: 20S and '32S' are the products of site #3 cleavage in the first pathway and '36S' is the substrate for cleavage at site #3 in the second pathway. We postulate that U3 snRNP folds pre-rRNA into a conformation dictating correct cleavage at processing site #3. |
12643937 | Signaling pathways that respond to DNA damage are essential for the maintenance of genome stability and are linked to many diseases, including cancer. Here, a genome-wide siRNA screen was employed to identify additional genes involved in genome stabilization by monitoring phosphorylation of the histone variant H2AX, an early mark of DNA damage. We identified hundreds of genes whose downregulation led to elevated levels of H2AX phosphorylation (gammaH2AX) and revealed links to cellular complexes and to genes with unclassified functions. We demonstrate a widespread role for mRNA-processing factors in preventing DNA damage, which in some cases is caused by aberrant RNA-DNA structures. Furthermore, we connect increased gammaH2AX levels to the neurological disorder Charcot-Marie-Tooth (CMT) syndrome, and we find a role for several CMT proteins in the DNA-damage response. These data indicate that preservation of genome stability is mediated by a larger network of biological processes than previously appreciated. |
12658073 | The gut microbiota has been proposed as an environmental factor that affects the development of metabolic and inflammatory diseases in mammals. Recent reports indicate that gut bacteria-derived lipopolysaccharide (LPS) can initiate obesity and insulin resistance in mice; however, the molecular interactions responsible for microbial regulation of host metabolism and mediators of inflammation have not been studied in detail. Hepatic serum amyloid A (SAA) proteins are markers and proposed mediators of inflammation that exhibit increased levels in serum of insulin-resistant mice. Adipose tissue-derived SAA3 displays monocyte chemotactic activity and may play a role in metabolic inflammation associated with obesity and insulin resistance. To investigate a potential mechanistic link between the intestinal microbiota and induction of proinflammatory host factors, we performed molecular analyses of germ-free, conventionally raised and genetically modified Myd88-/- mouse models. SAA3 expression was determined to be significantly augmented in adipose (9.9+/-1.9-fold; P<0.001) and colonic tissue (7.0+/-2.3-fold; P<0.05) by the presence of intestinal microbes. In the colon, we provided evidence that SAA3 is partially regulated through the Toll-like receptor (TLR)/MyD88/NF-kappaB signaling axis. We identified epithelial cells and macrophages as cellular sources of SAA3 in the colon and found that colonic epithelial expression of SAA3 may be part of an NF-kappaB-dependent response to LPS from gut bacteria. In vitro experiments showed that LPS treatments of both epithelial cells and macrophages induced SAA3 expression (27.1+/-2.5-fold vs. 1.6+/-0.1-fold, respectively). Our data suggest that LPS, and potentially other products of the indigenous gut microbiota, might elevate cytokine expression in tissues and thus exacerbate chronic low-grade inflammation observed in obesity. |
12667988 | Twenty-seven migraine headache patients were divided into three equal groups which received thermal biofeedback, frontalis EMG biofeedback, or relaxation training. Training was given under "massed" practice conditions (nine sessions per week) and consisted of 18 training sessions and six test-generalisation sessions. While improvements in headaches were observed in all groups, the best improvements took place in the thermal biofeedback group, which had almost complete elimination of migraine attacks by the end of training, and maintained that performance as long as six months after training. Examination of the patterns of skin temperature and EMG changes in the three groups over the course of training also points to a relationship between skin temperature control and reduction in migraine headache symptomatology, and suggests that this relationship is worthy of further investigation. |
12670680 | In systemic lupus erythematosus (SLE), self-reactive antibodies can target the kidney (lupus nephritis), leading to functional failure and possible mortality. We report that activation of basophils by autoreactive IgE causes their homing to lymph nodes, promoting T helper type 2 (T(H)2) cell differentiation and enhancing the production of self-reactive antibodies that cause lupus-like nephritis in mice lacking the Src family protein tyrosine kinase Lyn (Lyn(-/-) mice). Individuals with SLE also have elevated serum IgE, self-reactive IgEs and activated basophils that express CD62 ligand (CD62L) and the major histocompatibility complex (MHC) class II molecule human leukocyte antigen-DR (HLA-DR), parameters that are associated with increased disease activity and active lupus nephritis. Basophils were also present in the lymph nodes and spleen of subjects with SLE. Thus, in Lyn(-/-) mice, basophils and IgE autoantibodies amplify autoantibody production that leads to lupus nephritis, and in individuals with SLE IgE autoantibodies and activated basophils are factors associated with disease activity and nephritis. |
12672066 | IMPORTANCE In 2011, the Centers for Medicare & Medicaid Services (CMS) approved intensive behavioral weight loss counseling for approximately 14 face-to-face, 10- to 15-minute sessions over 6 months for obese beneficiaries in primary care settings, when delivered by physicians and other CMS-defined primary care practitioners. OBJECTIVE To conduct a systematic review of behavioral counseling for overweight and obese patients recruited from primary care, as delivered by primary care practitioners working alone or with trained interventionists (eg, medical assistants, registered dietitians), or by trained interventionists working independently. EVIDENCE REVIEW We searched PubMed, CINAHL, and EMBASE for randomized controlled trials published between January 1980 and June 2014 that recruited overweight and obese patients from primary care; provided behavioral counseling (ie, diet, exercise, and behavioral therapy) for at least 3 months, with at least 6 months of postrandomization follow-up; included at least 15 participants per treatment group and objectively measured weights; and had a comparator, an intention-to-treat analysis, and attrition of less than 30% at 1 year or less than 40% at longer follow-up. FINDINGS Review of 3304 abstracts yielded 12 trials, involving 3893 participants, that met inclusion-exclusion criteria and prespecified quality ratings. No studies were found in which primary care practitioners delivered counseling that followed the CMS guidelines. Mean 6-month weight changes from baseline in the intervention groups ranged from a loss of 0.3 kg to 6.6 kg. In the control group, mean change ranged from a gain of 0.9 kg to a loss of 2.0 kg. Weight loss in both groups generally declined with longer follow-up (12-24 months). Interventions that prescribed both reduced energy intake (eg, ≥ 500 kcal/d) and increased physical activity (eg, ≥150 minutes a week of walking), with traditional behavioral therapy, generally produced larger weight loss than interventions without all 3 specific components. In the former trials, more treatment sessions, delivered in person or by telephone by trained interventionists, were associated with greater mean weight loss and likelihood of patients losing 5% or more of baseline weight. CONCLUSIONS AND RELEVANCE Intensive behavioral counseling can induce clinically meaningful weight loss, but there is little research on primary care practitioners providing such care. The present findings suggest that a range of trained interventionists, who deliver counseling in person or by telephone, could be considered for treating overweight or obesity in patients encountered in primary care settings. |
12685434 | Although GBP1 (guanylate binding protein 1) was among the first interferon-inducible proteins identified, its function is still largely unknown. Epidermal growth factor receptor (EGFR) activation by amplification or mutation is one of the most frequent genetic lesions in a variety of human tumors. These include glioblastoma multiforme (GBM), which is characterized by independent but interrelated features of extensive invasion into normal brain parenchyma, rapid growth, necrosis, and angiogenesis. In this study, we show that EGFR activation promoted GBP1 expression in GBM cell lines through a signaling pathway involving Src and p38 mitogen-activated protein kinase. Moreover, we identified YY1 (Yin Yang 1) as the downstream transcriptional regulator regulating EGFR-driven GBP1 expression. GBP1 was required for EGFR-mediated MMP1 (matrix metalloproteinase 1) expression and glioma cell invasion in vitro. Although deregulation of GBP1 expression did not affect glioma cell proliferation, overexpression of GBP1 enhanced glioma cell invasion through MMP1 induction, which required its C-terminal helical domain and was independent of its GTPase activity. Reducing GBP1 levels by RNA interference in invasive GBM cells also markedly inhibited their ability to infiltrate the brain parenchyma of mice. GBP1 expression was high and positively correlated with EGFR expression in human GBM tumors and cell lines, particularly those of the neural subtype. Together, these findings establish GBP1 as a previously unknown link between EGFR activity and MMP1 expression and nominate it as a novel potential therapeutic target for inhibiting GBM invasion. |
12691537 | The archaeal ATPase complex PAN, the homolog of the eukaryotic 26S proteasome-regulatory ATPases, was shown to associate transiently with the 20S proteasome upon binding of ATP or ATPgammaS, but not ADP. By electron microscopy (EM), PAN appears as a two-ring structure, capping the 20S, and resembles two densities in the 19S complex. The N termini of the archaeal 20S alpha subunits were found to function as a gate that prevents entry of seven-residue peptides but allows entry of tetrapeptides. Upon association with the 20S particle, PAN stimulates gate opening. Although degradation of globular proteins requires ATP hydrolysis, the PAN-20S complex with ATPgammaS translocates and degrades unfolded and denatured proteins. Rabbit 26S proteasomes also degrade these unfolded proteins upon ATP binding, without hydrolysis. Thus, although unfolding requires energy from ATP hydrolysis, ATP binding alone supports ATPase-20S association, gate opening, and translocation of unfolded substrates into the proteasome, which can occur by facilitated diffusion through the ATPase. |
12737132 | The YAP transcription coactivator has been implicated as an oncogene and is amplified in human cancers. Recent studies have established that YAP is phosphorylated and inhibited by the Hippo tumor suppressor pathway. Here we demonstrate that the TEAD family transcription factors are essential in mediating YAP-dependent gene expression. TEAD is also required for YAP-induced cell growth, oncogenic transformation, and epithelial-mesenchymal transition. CTGF is identified as a direct YAP target gene important for cell growth. Moreover, the functional relationship between YAP and TEAD is conserved in Drosophila Yki (the YAP homolog) and Scalloped (the TEAD homolog). Our study reveals TEAD as a new component in the Hippo pathway playing essential roles in mediating biological functions of YAP. |
12770738 | BACKGROUND Questions remain as to whether higher levels of cardiorespiratory fitness, a measure of regular physical activity, are associated with lower risk of cardiovascular disease (CVD) mortality in overweight and obese individuals with diabetes. Our objective was to quantify the independent and joint relations of cardiorespiratory fitness (hereafter, fitness) and body mass index (BMI; calculated as weight in kilograms divided by the square of height in meters) with CVD mortality in men with diabetes. METHODS This study was conducted using prospective observational data from the Aerobics Center Longitudinal Study. Study participants comprised 2316 men with no history of stroke or myocardial infarction and who were diagnosed as having diabetes (mean [SD] age, 50 [10] years); had a medical examination, including a maximal exercise test during 1970 to 1997 with mortality surveillance to December 31, 1998; and had a BMI of 18.5 or greater and less than 35.0. The main outcome measure was CVD mortality across levels of fitness with stratification by BMI. RESULTS We identified 179 CVD deaths during a mean (SD) follow-up of 15.9 (7.9) years and 36,710 man-years of exposure. In a model containing age, examination year, fasting glucose level, systolic blood pressure, parental history of premature CVD, total cholesterol level, cigarette smoking, abnormal resting, and exercise electrocardiograms, a significantly higher adjusted risk of mortality was observed in men with a low fitness level who were normal weight (hazard ratio, 2.7 [95% confidence interval, 1.3-5.7]), overweight (hazard ratio, 2.7 [95% confidence interval, 1.4-5.1]), and class 1 obese (hazard ratio, 2.8 [95% confidence interval, 1.4-5.1]) compared with normal weight men with a high fitness level. CONCLUSION In this cohort of men with diabetes, low fitness level was associated with increased risk of CVD mortality within normal weight, overweight, and class 1 obese weight categories. |
12779444 | The number of women dying from cervical cancer in 1997 was 7% lower than in 1996 and has fallen by over 25% since 1992.1 Such rapid change must be at least partly due to cervical screening, although strong cohort effects have caused large fluctuations in cervical mortality in the past.2 We modelled mortality data, taking into account the effects of age and year of birth and looking for trends in time within four age groups to estimate the beneficial effects of cervical screening. We obtained mortality data, in 5 year age bands, from death registrations in England and Wales and calculated rates using mid-year population estimates. Mortality since 1993 was adjusted upwards by 4% because of changes in classification of cause of death.3 We modelled the data assuming that the age specific mortality is the product of a smoothly varying age effect, birth cohort effect, and age dependent … |
12794099 | BACKGROUND There is overwhelming evidence that behavioural factors influence health, but their combined impact on the general population is less well documented. We aimed to quantify the potential combined impact of four health behaviours on mortality in men and women living in the general community. METHODS AND FINDINGS We examined the prospective relationship between lifestyle and mortality in a prospective population study of 20,244 men and women aged 45-79 y with no known cardiovascular disease or cancer at baseline survey in 1993-1997, living in the general community in the United Kingdom, and followed up to 2006. Participants scored one point for each health behaviour: current non-smoking, not physically inactive, moderate alcohol intake (1-14 units a week) and plasma vitamin C >50 mmol/l indicating fruit and vegetable intake of at least five servings a day, for a total score ranging from zero to four. After an average 11 y follow-up, the age-, sex-, body mass-, and social class-adjusted relative risks (95% confidence intervals) for all-cause mortality(1,987 deaths) for men and women who had three, two, one, and zero compared to four health behaviours were respectively, 1.39 (1.21-1.60), 1.95 (1.70--2.25), 2.52 (2.13-3.00), and 4.04 (2.95-5.54) p < 0.001 trend. The relationships were consistent in subgroups stratified by sex, age, body mass index, and social class, and after excluding deaths within 2 y. The trends were strongest for cardiovascular causes. The mortality risk for those with four compared to zero health behaviours was equivalent to being 14 y younger in chronological age. CONCLUSIONS Four health behaviours combined predict a 4-fold difference in total mortality in men and women, with an estimated impact equivalent to 14 y in chronological age. |
12800122 | Subdividing proliferating tissues into compartments is an evolutionarily conserved strategy of animal development [1-6]. Signals across boundaries between compartments can result in local expression of secreted proteins organizing growth and patterning of tissues [1-6]. Sharp and straight interfaces between compartments are crucial for stabilizing the position of such organizers and therefore for precise implementation of body plans. Maintaining boundaries in proliferating tissues requires mechanisms to counteract cell rearrangements caused by cell division; however, the nature of such mechanisms remains unclear. Here we quantitatively analyzed cell morphology and the response to the laser ablation of cell bonds in the vicinity of the anteroposterior compartment boundary in developing Drosophila wings. We found that mechanical tension is approximately 2.5-fold increased on cell bonds along this compartment boundary as compared to the remaining tissue. Cell bond tension is decreased in the presence of Y-27632 [7], an inhibitor of Rho-kinase whose main effector is Myosin II [8]. Simulations using a vertex model [9] demonstrate that a 2.5-fold increase in local cell bond tension suffices to guide the rearrangement of cells after cell division to maintain compartment boundaries. Our results provide a physical mechanism in which the local increase in Myosin II-dependent cell bond tension directs cell sorting at compartment boundaries. |