Mechanism for CCC DNA Synthesis in Hepadnaviruses

Hepadnavirus replication requires the synthesis of a covalently closed circular (CCC) DNA from the relaxed circular (RC) viral genome by an unknown mechanism. CCC DNA formation could require enzymatic activities of the viral reverse transcriptase (RT), or cellular DNA repair enzymes, or both. Physical mapping of the 5′ and 3′ ends of RC DNA and sequence analysis of CCC DNA revealed that CCC DNA synthesis requires the removal of the RT and an RNA oligomer from the 5′ ends of minus and plus strand DNA, respectively, removal of sequences from the terminally redundant minus strand, completion of the less than full-length plus strand, and ligation of the ends. Two models have been proposed that could explain CCC DNA formation. The first (model 1) invokes a role for the RT to catalyze a cleavage-ligation reaction leading to the formation of a unit length minus strand in CCC DNA and a DNA repair reaction for the completion and ligation of plus strand DNA; the second (model 2) predicts that CCC DNA formation depends entirely on cellular DNA repair enzymes. To determine which mechanism is utilized, we developed cell lines expressing duck hepatitis B virus genomes carrying mutations permitting us to follow the fate of viral DNA sequences during their conversion from RC to CCC DNA. Our results demonstrated that the oligomer at the 5′ end of minus strand DNA is completely or at least partially removed prior to CCC DNA synthesis. The results indicated that both RC DNA strands undergo DNA repair reactions carried out by the cellular DNA repair machinery as predicted by model 2. Thus, our study provided the basis for the identification of the cellular components required for CCC DNA formation

3D-XY critical fluctuations of the thermal expansivity in detwinned YBa2Cu3O7-d single crystals near optimal doping

The strong coupling of superconductivity to the orthorhombic distortion in YBa2Cu3O7-d makes possible an analysis of the superconducting fluctuations without the necessity of subtracting any background. The present high-resolution capacitance dilatometry data unambiguously demonstrate the existence of critical, instead of Gaussian, fluctuations over a wide temperature region (+/- 10 K) around Tc. The values of the amplitude ratio A+/A-=0.9-1.1 and the leading scaling exponent |alpha|<0.018, determined via a least-squares fit of the data, are consistent with the 3D-XY universality class. Small deviations from pure 3D-XY behavior are discussed.Comment: 11 pages including three figure

Statistical strategy for stereospecific hydrogen NMR assignments: Validation procedures for the floating prochirality method

We examine the statistical and other considerations which determine the validity and reproducibility of stereospecific hydrogen NMR assignments obtained by the floating prochirality method. In this method, the assignment of a prochiral configuration of hydrogens at selected centers is allowed to ‘float’ during the structure refinement, and the distribution of prochiral orientations in highly refined structures is subjected to statistical analysis. The underlying statistical basis for this approach is examined and potential limitations of current approaches are identified. As an example, approximately 1300 distance constraints obtained from NOESY spectra of oxidized horse cytochrome c have been used to examine several computational strategies. Repeated calculations were done by several different methods on both the whole molecule (104 residues plus heme) and on a 23-residue fragment containing two helices, a turn, and flanking residues. The results show that, even with NOE constraints alone, one third of the centers may be reproducibly assigned, provided appropriate precautions are taken. These precautions include adjustments for multiple statistical comparisons and characterization of statistical interactions between prochiral centers. The analysis demonstrates that inadequately constrained systems, such as fragments from a larger molecule, may produce misleading results, raising concerns about methods which rely solely on intraresidue and sequential interresidue contraints. A mathematical model describing interactions among prochiral centers is described and validated, and protocols for assignment and statistical validation are presented.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43048/1/10858_2004_Article_BF00198371.pd

Induction of Ovarian Leiomyosarcomas in Mice by Conditional Inactivation of Brca1 and p53

gene is often found in patients with inherited breast and ovarian cancer syndrome..associated inherited EOC

Phase II Study of Paclitaxel, Carboplatin, and Cetuximab as First Line Treatment, for Patients with Advanced Non-small Cell Lung Cancer (NSCLC): Results of OPN-017

BackgroundCetuximab has demonstrated synergy with taxanes in preclinical models; as well as single agent activity. We assessed the activity of cetuximab with carboplatin and paclitaxel given on a 4-week schedule, in advanced, chemo-naive non-small cell lung cancer.Patients and MethodsThis phase II, single arm, multi-institution study featured standard dosage of cetuximab 400 mg/m2 day 1, then 250 mg/m2 with paclitaxel (100 mg/m2/wk, for 3 weeks), and carboplatin (area under curve = 6) day 1 of each 28 day cycle. After 4 to 6 cycles, in the absence of disease progression or excess toxicity, cetuximab was continued weekly. Primary end point was response rate.ResultsFifty-three patients (median age 63, 51% male) participated. Response rate was 57% (3 complete response and 27 partial response). At a median follow-up of 12.5 months, the estimated overall survival is 13.8 months (95% CI: 9.08–16.02) with an event-free survival rate of 5.53 months (95% CI: 4.77–7.99), 18.9% remain free from progression at 1 year. Improved survival was associated with female gender, absence of prior radiation, PS 0 and epidermal growth factor receptor expression. Toxicities included rash (28% grade 3), nail changes (3.7% grade 3), hypomagnesemia (7.5% grade 3 and 3.7% grade 4), and neutropenia (25% grade 3 and 13% grade 4) in addition to other typical side effects anticipated with paclitaxel/carboplatin. There were no grade 5 toxicities.ConclusionCombination of cetuximab/paclitaxel/carboplatin in non-small cell lung cancer was well tolerated and clinically active with manageable toxicities. This unique schedule, integrating weekly paclitaxel and cetuximab has not yet been tested in a randomized trial

Targeted hepatitis C antibody testing interventions: a systematic review and meta-analysis

Testing for hepatitis C virus (HCV) infection may reduce the risk of liver-related morbidity, by facilitating earlier access to treatment and care. This review investigated the effectiveness of targeted testing interventions on HCV case detection, treatment uptake, and prevention of liver-related morbidity. A literature search identified studies published up to 2013 that compared a targeted HCV testing intervention (targeting individuals or groups at increased risk of HCV) with no targeted intervention, and results were synthesised using meta-analysis. Exposure to a targeted testing intervention, compared to no targeted intervention, was associated with increased cases detected [number of studies (n) = 14; pooled relative risk (RR) 1.7, 95 % CI 1.3, 2.2] and patients commencing therapy (n = 4; RR 3.3, 95 % CI 1.1, 10.0). Practitioner-based interventions increased test uptake and cases detected (n = 12; RR 3.5, 95 % CI 2.5, 4.8; and n = 10; RR 2.2, 95 % CI 1.4, 3.5, respectively), whereas media/information-based interventions were less effective (n = 4; RR 1.5, 95 % CI 0.7, 3.0; and n = 4; RR 1.3, 95 % CI 1.0, 1.6, respectively). This meta-analysis provides for the first time a quantitative assessment of targeted HCV testing interventions, demonstrating that these strategies were effective in diagnosing cases and increasing treatment uptake. Strategies involving practitioner-based interventions yielded the most favourable outcomes. It is recommended that testing should be targeted at and offered to individuals who are part of a population with high HCV prevalence, or who have a history of HCV risk behaviour

HBV DNA Integration and Clonal Hepatocyte Expansion in Chronic Hepatitis B Patients Considered Immune Tolerant

BACKGROUND & AIMS: Chronic hepatitis B virus (HBV) infection is characterized clinically by progression through disease phases. The first, labeled immune tolerant (IT), is perceived to lack disease activity. Here, we examined HBV-DNA integration, clonal hepatocyte expansion, HBV antigen expression and HBV-specific immunity in patients considered IT to assess whether this designation is appropriate, or if pathological changes may be present. METHODS: HBV-DNA integration, clonal hepatocyte expansion, HBsAg and HBcAg expression were studied in liver tissue from CHB patients, (age 14–39 years; median=24.5). These included 9 HBeAg(+) IT patients. Ten HBeAg(+) and 7 HBeAg(−) age-matched patients with active disease served as controls. HBV-specific T cells were quantified in paired peripheral blood lymphocytes. RESULTS: HBV antigen expression differed between the patient groups. However, unexpectedly high numbers of HBV-DNA integrations, randomly distributed across most chromosomes, were detectable in all patient groups. Patients considered IT also displayed significant clonal hepatocyte expansion, potentially in response to active HBV-specific T cell immunity. HBV-specific T cell responses were also confirmed in the periphery of these patients. CONCLUSIONS: A high level of HBV DNA integration and clonal hepatocyte expansion in patients considered IT suggests that events in hepatocarcinogenesis are underway even in the early stages of CHB. The concept that the IT phase is devoid of markers of disease progression and is immunologically inert is unsupported; instead, we propose that high replicative low inflammatory (HRLI) CHB more accurately reflects this early disease phase. The timing of therapeutic intervention to minimize further genetic damage to the hepatocyte population should be reconsidered

Height and body-mass index trajectories of school-aged children and adolescents from 1985 to 2019 in 200 countries and territories: a pooled analysis of 2181 population-based studies with 65 million participants

Summary Background Comparable global data on health and nutrition of school-aged children and adolescents are scarce. We aimed to estimate age trajectories and time trends in mean height and mean body-mass index (BMI), which measures weight gain beyond what is expected from height gain, for school-aged children and adolescents. Methods For this pooled analysis, we used a database of cardiometabolic risk factors collated by the Non-Communicable Disease Risk Factor Collaboration. We applied a Bayesian hierarchical model to estimate trends from 1985 to 2019 in mean height and mean BMI in 1-year age groups for ages 5–19 years. The model allowed for non-linear changes over time in mean height and mean BMI and for non-linear changes with age of children and adolescents, including periods of rapid growth during adolescence. Findings We pooled data from 2181 population-based studies, with measurements of height and weight in 65 million participants in 200 countries and territories. In 2019, we estimated a difference of 20 cm or higher in mean height of 19-year-old adolescents between countries with the tallest populations (the Netherlands, Montenegro, Estonia, and Bosnia and Herzegovina for boys; and the Netherlands, Montenegro, Denmark, and Iceland for girls) and those with the shortest populations (Timor-Leste, Laos, Solomon Islands, and Papua New Guinea for boys; and Guatemala, Bangladesh, Nepal, and Timor-Leste for girls). In the same year, the difference between the highest mean BMI (in Pacific island countries, Kuwait, Bahrain, The Bahamas, Chile, the USA, and New Zealand for both boys and girls and in South Africa for girls) and lowest mean BMI (in India, Bangladesh, Timor-Leste, Ethiopia, and Chad for boys and girls; and in Japan and Romania for girls) was approximately 9–10 kg/m2. In some countries, children aged 5 years started with healthier height or BMI than the global median and, in some cases, as healthy as the best performing countries, but they became progressively less healthy compared with their comparators as they grew older by not growing as tall (eg, boys in Austria and Barbados, and girls in Belgium and Puerto Rico) or gaining too much weight for their height (eg, girls and boys in Kuwait, Bahrain, Fiji, Jamaica, and Mexico; and girls in South Africa and New Zealand). In other countries, growing children overtook the height of their comparators (eg, Latvia, Czech Republic, Morocco, and Iran) or curbed their weight gain (eg, Italy, France, and Croatia) in late childhood and adolescence. When changes in both height and BMI were considered, girls in South Korea, Vietnam, Saudi Arabia, Turkey, and some central Asian countries (eg, Armenia and Azerbaijan), and boys in central and western Europe (eg, Portugal, Denmark, Poland, and Montenegro) had the healthiest changes in anthropometric status over the past 3·5 decades because, compared with children and adolescents in other countries, they had a much larger gain in height than they did in BMI. The unhealthiest changes—gaining too little height, too much weight for their height compared with children in other countries, or both—occurred in many countries in sub-Saharan Africa, New Zealand, and the USA for boys and girls; in Malaysia and some Pacific island nations for boys; and in Mexico for girls. Interpretation The height and BMI trajectories over age and time of school-aged children and adolescents are highly variable across countries, which indicates heterogeneous nutritional quality and lifelong health advantages and risks

Rising rural body-mass index is the main driver of the global obesity epidemic in adults

Body-mass index (BMI) has increased steadily in most countries in parallel with a rise in the proportion of the population who live in cities(.)(1,2) This has led to a widely reported view that urbanization is one of the most important drivers of the global rise in obesity(3-6). Here we use 2,009 population-based studies, with measurements of height and weight in more than 112 million adults, to report national, regional and global trends in mean BMI segregated by place of residence (a rural or urban area) from 1985 to 2017. We show that, contrary to the dominant paradigm, more than 55% of the global rise in mean BMI from 1985 to 2017-and more than 80% in some low- and middle-income regions-was due to increases in BMI in rural areas. This large contribution stems from the fact that, with the exception of women in sub-Saharan Africa, BMI is increasing at the same rate or faster in rural areas than in cities in low- and middle-income regions. These trends have in turn resulted in a closing-and in some countries reversal-of the gap in BMI between urban and rural areas in low- and middle-income countries, especially for women. In high-income and industrialized countries, we noted a persistently higher rural BMI, especially for women. There is an urgent need for an integrated approach to rural nutrition that enhances financial and physical access to healthy foods, to avoid replacing the rural undernutrition disadvantage in poor countries with a more general malnutrition disadvantage that entails excessive consumption of low-quality calories.Peer reviewe