DNA Structure Modulates the Oligomerization Properties of the AAV Initiator Protein Rep68

Rep68 is a multifunctional protein of the adeno-associated virus (AAV), a parvovirus that is mostly known for its promise as a gene therapy vector. In addition to its role as initiator in viral DNA replication, Rep68 is essential for site-specific integration of the AAV genome into human chromosome 19. Rep68 is a member of the superfamily 3 (SF3) helicases, along with the well-studied initiator proteins simian virus 40 large T antigen (SV40-LTag) and bovine papillomavirus (BPV) E1. Structurally, SF3 helicases share two domains, a DNA origin interaction domain (OID) and an AAA+ motor domain. The AAA+ motor domain is also a structural feature of cellular initiators and it functions as a platform for initiator oligomerization. Here, we studied Rep68 oligomerization in vitro in the presence of different DNA substrates using a variety of biophysical techniques and cryo-EM. We found that a dsDNA region of the AAV origin promotes the formation of a complex containing five Rep68 subunits. Interestingly, non-specific ssDNA promotes the formation of a double-ring Rep68, a known structure formed by the LTag and E1 initiator proteins. The Rep68 ring symmetry is 8-fold, thus differing from the hexameric rings formed by the other SF3 helicases. However, similiar to LTag and E1, Rep68 rings are oriented head-to-head, suggesting that DNA unwinding by the complex proceeds bidirectionally. This novel Rep68 quaternary structure requires both the DNA binding and AAA+ domains, indicating cooperativity between these regions during oligomerization in vitro. Our study clearly demonstrates that Rep68 can oligomerize through two distinct oligomerization pathways, which depend on both the DNA structure and cooperativity of Rep68 domains. These findings provide insight into the dynamics and oligomeric adaptability of Rep68 and serve as a step towards understanding the role of this multifunctional protein during AAV DNA replication and site-specific integration

European guidelines on microscopic colitis: United European Gastroenterology (UEG) and European Microscopic Colitis Group (EMCG) statements and recommendations

INTRODUCTION: Microscopic colitis is a chronic inflammatory bowel disease characterised by normal or almost normal endoscopic appearance of the colon, chronic watery, non-bloody diarrhoea and distinct histological abnormalities, which identify three histological subtypes, the collagenous colitis, the lymphocytic colitis and the incomplete microscopic colitis. With ongoing uncertainties and new developments in the clinical management of microscopic colitis, there is a need for evidence-based guidelines to improve the medical care of patients suffering from this disorder. METHODS: Guidelines were developed by members from the European Microscopic Colitis Group and United European Gastroenterology in accordance with the Appraisal of Guidelines for Research and Evaluation II instrument. Following a systematic literature review, the Grading of Recommendations Assessment, Development and Evaluation methodology was used to assess the certainty of the evidence. Statements and recommendations were developed by working groups consisting of gastroenterologists, pathologists and basic scientists, and voted upon using the Delphi method. RESULTS: These guidelines provide information on epidemiology and risk factors of microscopic colitis, as well as evidence-based statements and recommendations on diagnostic criteria and treatment options, including oral budesonide, bile acid binders, immunomodulators and biologics. Recommendations on the clinical management of microscopic colitis are provided based on evidence, expert opinion and best clinical practice. CONCLUSION: These guidelines may support clinicians worldwide to improve the clinical management of patients with microscopic colitis

Nutrition and dietary intake and their association with mortality and hospitalisation in adults with chronic kidney disease treated with haemodialysis: protocol for DIET-HD, a prospective multinational cohort study

INTRODUCTION: Adults with end-stage kidney disease (ESKD) treated with haemodialysis experience mortality of between 15% and 20% each year. Effective interventions that improve health outcomes for long-term dialysis patients remain unproven. Novel and testable determinants of health in dialysis are needed. Nutrition and dietary patterns are potential factors influencing health in other health settings that warrant exploration in multinational studies in men and women treated with dialysis. We report the protocol of the "DIETary intake, death and hospitalisation in adults with end-stage kidney disease treated with HaemoDialysis (DIET-HD) study," a multinational prospective cohort study. DIET-HD will describe associations of nutrition and dietary patterns with major health outcomes for adults treated with dialysis in several countries.METHODS AND ANALYSIS: DIET-HD will recruit approximately 10,000 adults who have ESKD treated by clinics administered by a single dialysis provider in Argentina, France, Germany, Hungary, Italy, Poland, Portugal, Romania, Spain, Sweden and Turkey. Recruitment will take place between March 2014 and June 2015. The study has currently recruited 8000 participants who have completed baseline data. Nutritional intake and dietary patterns will be measured using the Global Allergy and Asthma European Network (GA(2)LEN) food frequency questionnaire. The primary dietary exposures will be n-3 and n-6 polyunsaturated fatty acid consumption. The primary outcome will be cardiovascular mortality and secondary outcomes will be all-cause mortality, infection-related mortality and hospitalisation.ETHICS AND DISSEMINATION: The study is approved by the relevant Ethics Committees in participating countries. All participants will provide written informed consent and be free to withdraw their data at any time. The findings of the study will be disseminated through peer-reviewed journals, conference presentations and to participants via regular newsletters. We expect that the DIET-HD study will inform large pragmatic trials of nutrition or dietary interventions in the setting of advanced kidney disease

Nutrition and dietary intake and their association with mortality and hospitalisation in adults with chronic kidney disease treated with haemodialysis: protocol for DIET-HD, a prospective multinational cohort study.

INTRODUCTION: Adults with end-stage kidney disease (ESKD) treated with haemodialysis experience mortality of between 15% and 20% each year. Effective interventions that improve health outcomes for long-term dialysis patients remain unproven. Novel and testable determinants of health in dialysis are needed. Nutrition and dietary patterns are potential factors influencing health in other health settings that warrant exploration in multinational studies in men and women treated with dialysis. We report the protocol of the "DIETary intake, death and hospitalisation in adults with end-stage kidney disease treated with HaemoDialysis (DIET-HD) study," a multinational prospective cohort study. DIET-HD will describe associations of nutrition and dietary patterns with major health outcomes for adults treated with dialysis in several countries.METHODS AND ANALYSIS: DIET-HD will recruit approximately 10,000 adults who have ESKD treated by clinics administered by a single dialysis provider in Argentina, France, Germany, Hungary, Italy, Poland, Portugal, Romania, Spain, Sweden and Turkey. Recruitment will take place between March 2014 and June 2015. The study has currently recruited 8000 participants who have completed baseline data. Nutritional intake and dietary patterns will be measured using the Global Allergy and Asthma European Network (GA(2)LEN) food frequency questionnaire. The primary dietary exposures will be n-3 and n-6 polyunsaturated fatty acid consumption. The primary outcome will be cardiovascular mortality and secondary outcomes will be all-cause mortality, infection-related mortality and hospitalisation.ETHICS AND DISSEMINATION: The study is approved by the relevant Ethics Committees in participating countries. All participants will provide written informed consent and be free to withdraw their data at any time. The findings of the study will be disseminated through peer-reviewed journals, conference presentations and to participants via regular newsletters. We expect that the DIET-HD study will inform large pragmatic trials of nutrition or dietary interventions in the setting of advanced kidney disease

The impact of surgical delay on resectability of colorectal cancer: An international prospective cohort study

AimThe SARS-CoV-2 pandemic has provided a unique opportunity to explore the impact of surgical delays on cancer resectability. This study aimed to compare resectability for colorectal cancer patients undergoing delayed versus non-delayed surgery.MethodsThis was an international prospective cohort study of consecutive colorectal cancer patients with a decision for curative surgery (January-April 2020). Surgical delay was defined as an operation taking place more than 4 weeks after treatment decision, in a patient who did not receive neoadjuvant therapy. A subgroup analysis explored the effects of delay in elective patients only. The impact of longer delays was explored in a sensitivity analysis. The primary outcome was complete resection, defined as curative resection with an R0 margin.ResultsOverall, 5453 patients from 304 hospitals in 47 countries were included, of whom 6.6% (358/5453) did not receive their planned operation. Of the 4304 operated patients without neoadjuvant therapy, 40.5% (1744/4304) were delayed beyond 4 weeks. Delayed patients were more likely to be older, men, more comorbid, have higher body mass index and have rectal cancer and early stage disease. Delayed patients had higher unadjusted rates of complete resection (93.7% vs. 91.9%, P = 0.032) and lower rates of emergency surgery (4.5% vs. 22.5%, P ConclusionOne in 15 colorectal cancer patients did not receive their planned operation during the first wave of COVID-19. Surgical delay did not appear to compromise resectability, raising the hypothesis that any reduction in long-term survival attributable to delays is likely to be due to micro-metastatic disease

Outcomes from elective colorectal cancer surgery during the SARS‐CoV‐2 pandemic

Aim This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic. Method This was an international cohort study of patients undergoing elective resection of colon or rectal cancer without preoperative suspicion of SARS-CoV-2. Centres entered data from their first recorded case of COVID-19 until 19 April 2020. The primary outcome was 30-day mortality. Secondary outcomes included anastomotic leak, postoperative SARS-CoV-2 and a comparison with prepandemic European Society of Coloproctology cohort data. Results From 2073 patients in 40 countries, 1.3% (27/2073) had a defunctioning stoma and 3.0% (63/2073) had an end stoma instead of an anastomosis only. Thirty-day mortality was 1.8% (38/2073), the incidence of postoperative SARS-CoV-2 was 3.8% (78/2073) and the anastomotic leak rate was 4.9% (86/1738). Mortality was lowest in patients without a leak or SARS-CoV-2 (14/1601, 0.9%) and highest in patients with both a leak and SARS-CoV-2 (5/13, 38.5%). Mortality was independently associated with anastomotic leak (adjusted odds ratio 6.01, 95% confidence interval 2.58–14.06), postoperative SARS-CoV-2 (16.90, 7.86–36.38), male sex (2.46, 1.01–5.93), age >70 years (2.87, 1.32–6.20) and advanced cancer stage (3.43, 1.16–10.21). Compared with prepandemic data, there were fewer anastomotic leaks (4.9% versus 7.7%) and an overall shorter length of stay (6 versus 7 days) but higher mortality (1.7% versus 1.1%). Conclusion Surgeons need to further mitigate against both SARS-CoV-2 and anastomotic leak when offering surgery during current and future COVID-19 waves based on patient, operative and organizational risks