Telomere length regulation: coupling DNA end processing to feedback regulation of telomerase

The conventional DNA polymerase machinery is unable to fully replicate the ends of linear chromosomes. To surmount this problem, nearly all eukaryotes use the telomerase enzyme, a specialized reverse transcriptase that utizes its own RNA template to add short TG-rich repeats to chromosome ends, thus reversing their gradual erosion occurring at each round of replication. This unique, non-DNA templated mode of telomere replication requires a regulatory mechanism to ensure that telomerase acts at telomeres whose TG tracts are too short, but not at those with long tracts, thus maintaining the protective TG repeat cap at an appropriate average length. The prevailing notion in the field is that telomere length regulation is brought about through a negative feedback mechanism that counts TG repeat-bound protein complexes to generate a signal that regulates telomerase action. This review summarizes experiments leading up to this model and then focuses on more recent experiments, primarily from yeast, that begin to suggest how this counting mechanism might work. The emerging picture is that of a complex interplay between the conventional DNA replication machinery, DNA damage response factors, and a specialized set of proteins that help to recruit and regulate the telomerase enzyme

Fatal case of sorafenib-associated idiosyncratic hepatotoxicity in the adjuvant treatment of a patient with renal cell carcinoma.

BACKGROUND: Sorafenib is an orally available kinase inhibitor with activity at Raf, PDGFβ and VEGF receptors that is licensed for the treatment of advanced renal cell carcinoma (RCC) and hepatocellular carcinoma (HCC). Current evidence-based post-nephrectomy management of individuals with localized RCC consists of surveillance-based follow up. The SORCE trial is designed to investigate whether treatment with adjuvant sorafenib can reduce recurrence rates in this cohort. CASE PRESENTATION: Here we report an idiosyncratic reaction to sorafenib resulting in fatal hepatotoxicity and associated renal failure in a 62 year-old man treated with sorafenib within the SORCE trial. CONCLUSION: This is the first reported case of sorafenib exposure associated fatal toxicity in the adjuvant setting and highlights the unpredictable adverse effects of novel adjuvant therapies.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

Supervision and feedback for junior medical staff in Australian emergency departments: findings from the emergency medicine capacity assessment study

<p>Abstract</p> <p>Background</p> <p>Clinical supervision and feedback are important for the development of competency in junior doctors. This study aimed to determine the adequacy of supervision of junior medical staff in Australian emergency departments (EDs) and perceived feedback provided.</p> <p>Methods</p> <p>Semi-structured telephone surveys sought quantitative and qualitative data from ED Directors, Directors of Emergency Medicine Training, registrars and interns in 37 representative Australian hospitals; quantitative data were analysed with SPSS 15.0 and qualitative data subjected to content analysis identifying themes.</p> <p>Results</p> <p>Thirty six of 37 hospitals took part. Of 233 potential interviewees, 95 (40.1%) granted interviews including 100% (36/36) of ED Directors, and 96.2% (25/26) of eligible DEMTs, 24% (19/81) of advanced trainee/registrars, and 17% (15/90) of interns. Most participants (61%) felt the ED was adequately supervised in general and (64.2%) that medical staff were adequately supervised. Consultants and registrars were felt to provide most intern supervision, but this varied depending on shift times, with registrars more likely to provide supervision on night shift and at weekends. Senior ED medical staff (64%) and junior staff (79%) agreed that interns received adequate clinical supervision. Qualitative analysis revealed that good processes were in place to ensure adequate supervision, but that service demands, particularly related to access block and overcrowding, had detrimental effects on both supervision and feedback.</p> <p>Conclusions</p> <p>Consultants appear to provide the majority of supervision of junior medical staff in Australian EDs. Supervision and feedback are generally felt to be adequate, but are threatened by service demands, particularly related to access block and ED overcrowding.</p

Classification and Exploration of 3D Protein Domain Interactions Using Kbdock

International audienceComparing and classifying protein domain interactions according to theirthree-dimensional (3D) structures can help to understand protein structure-function and evolutionary relationships. Additionally, structural knowledge ofexisting domain–domain interactions can provide a useful way to findstructural templates with which to model the 3D structures of unsolvedprotein complexes. Here we present a straightforward guide to using the“Kbdock” protein domain structure database and its associated web site forexploring and comparing protein domain–domain interactions (DDIs) anddomain–peptide interactions (DPIs) at the Pfam domain family level. We alsobriefly explain how the Kbdock web site works, and we provide some notesand suggestions which should help to avoid some common pitfalls whenworking with 3D protein domain structures

Surgical Treatment of Renal Cell Cancer Liver Metastases: A Population-Based Study

Background: To evaluate outcomes of surgical treatment in patients with hepatic metastases from renal-cell carcinoma in the Netherlands, and to identify prognostic factors for survival after resection. Renal-cell carcinoma has an incidence of 2,000 new patients in the Netherlands each year (12.5/100,000 inhabitants). According to literature, half of these patients ultimately develop distant metastases with 20% involvement of the liver. Resection of renal-cell carcinoma liver metastases (RCCLM) is performed in only a minority of patients. Hence, little is known about outcome of resectable RCCLM. Methods: Patients were retrieved from local databases of theNetherlands Task Force for Liver Surgery (14 centers) and from the Dutch collective pathology database. Survival and prognostic factors were determined by Kaplan-Meier analysis and log rank test. Results: Thirty-three patients were identified who underwent resection (n = 29) or local ablation (n = 4) of RCCLM in the Netherlands between 1990 and 2008. These patients comprise 0.5% to 1% of the total population of patients diagnosed with RCCLM in that period. There was no operative mortality. The overall survival at 1, 3, and 5 years was 79, 47, and 43%, respectively. Metachronous metastases (n = 23, P = 0.03) and radical resection (n = 19, P < 0.001) were statistically significant prognosticators of ov

Flexible trial design in practice - stopping arms for lack-of-benefit and adding research arms mid-trial in STAMPEDE: a multi-arm multi-stage randomized controlled trial

Systemic Therapy for Advanced or Metastatic Prostate cancer: Evaluation of Drug Efficacy (STAMPEDE) is a randomized controlled trial that follows a novel multi-arm, multi-stage (MAMS) design. We describe methodological and practical issues arising with (1) stopping recruitment to research arms following a pre-planned intermediate analysis and (2) adding a new research arm during the trial

Actinobacillus pleuropneumoniae encodes multiple phase-variable DNA methyltransferases that control distinct phasevarions

Actinobacillus pleuropneumoniae is the cause of porcine pleuropneumonia, a severe respiratory tract infection that is responsible for major economic losses to the swine industry. Many host-adapted bacterial pathogens encode systems known as phasevarions (phase-variable regulons). Phasevarions result from variable expression of cytoplasmic DNA methyltransferases. Variable expression results in genome-wide methylation differences within a bacterial population, leading to altered expression of multiple genes via epigenetic mechanisms. Our examination of a diverse population of A. pleuropneumoniae strains determined that Type I and Type III DNA methyltransferases with the hallmarks of phase variation were present in this species. We demonstrate that phase variation is occurring in these methyltransferases, and show associations between particular Type III methyltransferase alleles and serovar. Using Pacific BioSciences Single-Molecule, Real-Time (SMRT) sequencing and Oxford Nanopore sequencing, we demonstrate the presence of the first ever characterised phase-variable, cytosine-specific Type III DNA methyltransferase. Phase variation of distinct Type III DNA methyltransferase in A. pleuropneumoniae results in the regulation of distinct phasevarions, and in multiple phenotypic differences relevant to pathobiology. Our characterisation of these newly described phasevarions in A. pleuropneumoniae will aid in the selection of stably expressed antigens, and direct and inform development of a rationally designed subunit vaccine against this major veterinary pathogen

Utilisation of an operative difficulty grading scale for laparoscopic cholecystectomy

Background A reliable system for grading operative difficulty of laparoscopic cholecystectomy would standardise description of findings and reporting of outcomes. The aim of this study was to validate a difficulty grading system (Nassar scale), testing its applicability and consistency in two large prospective datasets. Methods Patient and disease-related variables and 30-day outcomes were identified in two prospective cholecystectomy databases: the multi-centre prospective cohort of 8820 patients from the recent CholeS Study and the single-surgeon series containing 4089 patients. Operative data and patient outcomes were correlated with Nassar operative difficultly scale, using Kendall’s tau for dichotomous variables, or Jonckheere–Terpstra tests for continuous variables. A ROC curve analysis was performed, to quantify the predictive accuracy of the scale for each outcome, with continuous outcomes dichotomised, prior to analysis. Results A higher operative difficulty grade was consistently associated with worse outcomes for the patients in both the reference and CholeS cohorts. The median length of stay increased from 0 to 4 days, and the 30-day complication rate from 7.6 to 24.4% as the difficulty grade increased from 1 to 4/5 (both p < 0.001). In the CholeS cohort, a higher difficulty grade was found to be most strongly associated with conversion to open and 30-day mortality (AUROC = 0.903, 0.822, respectively). On multivariable analysis, the Nassar operative difficultly scale was found to be a significant independent predictor of operative duration, conversion to open surgery, 30-day complications and 30-day reintervention (all p < 0.001). Conclusion We have shown that an operative difficulty scale can standardise the description of operative findings by multiple grades of surgeons to facilitate audit, training assessment and research. It provides a tool for reporting operative findings, disease severity and technical difficulty and can be utilised in future research to reliably compare outcomes according to case mix and intra-operative difficulty

Molecular and Behavioral Differentiation among Brazilian Populations of Lutzomyia longipalpis (Diptera: Psychodidae: Phlebotominae)

Lutzomyia longipalpis is the main vector of visceral leishmaniasis in the Americas. There is strong evidence that L. longipalpis is a species complex, but there is still no consensus regarding the number of species occurring in Brazil. We combined molecular and behavioral analyses of a number of L. longipalpis populations in order to help clarify this question. This approach has allowed us to identify two main groups of populations in Brazil. One group probably represents a single species distributed mainly throughout the coastal regions of North and Northeast Brazil and whose males produce the same type of copulation song and pheromone. The second group is more heterogeneous, probably represented by a number of incipient species with different levels of genetic divergence among the siblings that produce different combinations of copulation songs and pheromones. The high level of complexity observed raises important questions concerning the epidemiological consequences of this incipient speciation process