High Folate, Perturbed One-Carbon Metabolism and Gestational Diabetes Mellitus

Folate is a dietary micronutrient essential to one-carbon metabolism. The World Health Organisation recommends folic acid (FA) supplementation pre-conception and in early pregnancy to reduce the risk of fetal neural tube defects (NTDs). Subsequently, many countries (~92) have mandatory FA fortification policies, as well as recommendations for periconceptional FA supplementation. Mandatory fortification initiatives have been largely successful in reducing the incidence of NTDs. However, humans have limited capacity to incorporate FA into the one-carbon metabolic pathway, resulting in the increasingly ubiquitous presence of circulating unmetabolised folic acid (uFA). Excess FA intake has emerged as a risk factor in gestational diabetes mellitus (GDM). Several other one-carbon metabolism components (vitamin B12, homocysteine and choline-derived betaine) are also closely entwined with GDM risk, suggesting a role for one-carbon metabolism in GDM pathogenesis. There is growing evidence from in vitro and animal studies suggesting a role for excess FA in dysregulation of one-carbon metabolism. Specifically, high levels of FA reduce methylenetetrahydrofolate reductase (MTHFR) activity, dysregulate the balance of thymidylate synthase (TS) and methionine synthase (MTR) activity, and elevate homocysteine. High homocysteine is associated with increased oxidative stress and trophoblast apoptosis and reduced human chorionic gonadotrophin (hCG) secretion and pancreatic β-cell function. While the relationship between high FA, perturbed one-carbon metabolism and GDM pathogenesis is not yet fully understood, here we summarise the current state of knowledge. Given rising rates of GDM, now estimated to be 14% globally, and widespread FA food fortification, further research is urgently needed to elucidate the mechanisms which underpin GDM pathogenesis.Jessica M. Williamson, Anya L. Arthurs, Melanie D. Smith, Claire T. Roberts, and Tanja Jankovic-Karasoulo

Exercise and pregnancy in recreational and elite athletes: 2016 evidence summary from the IOC expert group meeting, Lausanne. Part 1-exercise in women planning pregnancy and those who are pregnant

BACKGROUND Guidelines on physical activity or exercise and pregnancy encourage pregnant women to continue or adopt an active lifestyle during and following pregnancy.1-3 Two systematic reviews of pregnancy-related guidelines on physical activity found similarities between recommendations from different countries, but noted that the guidelines differed in focus.4 5 The guidelines provided variable guidance on prenatal exercise, or on how pregnant women might approach continuing or adopting sport activities.6 However, most guidelines did not include important topics such as prevalence and known risk factors for common pregnancy-related diseases and complaints, and the role of exercise in preventing and treating them. Importantly, the focus of most previous guidelines has been on healthy pregnant women in the general population, in whom there is almost always a decline in physical activity during pregnancy.7 8 Indeed, a high proportion of pregnant women follow neither physical activity nor exercise guidelines, 9 putting them at increased risk of obesity, gestational diabetes mellitus (GDM), and other pregnancy-related diseases and complaints.1 On the other hand, there are enthusiastic exercisers and elite athletes who often meet and exceed general exercise recommendations for pregnant women, but there are no exercise guidelines specifically for these women. Important questions for such women are unanswered in current guidelines: Which activities, exercises and sports can they perform, for how long and at what intensity, without risking their own health and the health of the fetus? How soon can they return to highintensity training and competition after childbirth? The IOC and most National Sports Federations encourage women to participate in all Olympic sport disciplines. The IOC promotes high-level performance, and it is also strongly committed to promoting lifelong health among athletes10-not just during their competitive sporting careers. With an increasing number of elite female athletes competing well into their thirties, many may wish to become pregnant, and some also want to continue to compete after childbirth. With this background, the IOC assembled an international expert committee to review the literature on physical activity and exercise (1) during pregnancy and (2) after childbirth, using rigorous systematic review and search criteria.11 For efficiency, where sex is not specified, the reader should assume that this manuscript about pregnancy and childbirth refers to females (ie, \u27the elite athlete who wishes to train at altitude\u27 is used in preference to \u27the elite female athlete...\u27). AIMS The September 2015 IOC meeting of 16 experts in Lausanne had three aims. They were to: 1. Summarise common conditions, illnesses and complaints that may interfere with strenuous exercise and competition, during pregnancy and after childbirth; 2. Provide recommendations for exercise training during pregnancy and after childbirth, for highlevel regular exercisers and elite athletes; and 3. Identify major gaps in the literature that limit the confidence with which recommendations can be made. METHODS For each section of the document, a search strategy was performed using search terms such as \u27pregnancy\u27 OR \u27pregnant\u27 OR \u27postpartum\u27 AND \u27exercise\u27 OR \u27physical activity\u27 OR\u27leisure activity\u27 OR\u27leisure\u27 OR \u27recreation\u27 OR \u27recreational activity\u27 or \u27physical fitness\u27 OR \u27occupational activity\u27 AND terms related to the condition under study (eg, \u27gestational diabetes\u27). Available databases were searched, with an emphasis on PubMed, EMBASE, Cochrane, PEDro, Web of Science and SPORTDiscus. In addition, existing guidelines with reference lists were scanned. The review of each topic followed the general order: prevalence of the condition in the general pregnant or postpartum population, prevalence in high-level exercisers or elite athletes, risk factors in the general population and in relation to exercise and sport, and effect of preventive and treatment interventions. Level of evidence and grade of recommendations are according to the Cochrane handbook (table 1) for prevention and treatment interventions only. Each member of the working group was assigned to be the lead author of one or more topics and 1-3 others were assigned to review each topic. A first full consensus draft was reviewed before and during the 3-day IOC meeting (27-29 September 2015), and a new version of each topic was submitted to the meeting chairs (KB and KMK) shortly after the meeting. Each topic leader made amendments before sending a new version for comments to the working group

Multiband tight-binding theory of disordered ABC semiconductor quantum dots: Application to the optical properties of alloyed CdZnSe nanocrystals

Zero-dimensional nanocrystals, as obtained by chemical synthesis, offer a broad range of applications, as their spectrum and thus their excitation gap can be tailored by variation of their size. Additionally, nanocrystals of the type ABC can be realized by alloying of two pure compound semiconductor materials AC and BC, which allows for a continuous tuning of their absorption and emission spectrum with the concentration x. We use the single-particle energies and wave functions calculated from a multiband sp^3 empirical tight-binding model in combination with the configuration interaction scheme to calculate the optical properties of CdZnSe nanocrystals with a spherical shape. In contrast to common mean-field approaches like the virtual crystal approximation (VCA), we treat the disorder on a microscopic level by taking into account a finite number of realizations for each size and concentration. We then compare the results for the optical properties with recent experimental data and calculate the optical bowing coefficient for further sizes

Clostridioides difficile canonical L,D-transpeptidases catalyze a novel type of peptidoglycan cross-links and are not required for beta-lactam resistance

Clostridioides difficile is the leading cause of antibiotic-associated diarrhea worldwide with significant morbidity and mortality. This organism is naturally resistant to several beta-lactam antibiotics that inhibit the polymerization of peptidoglycan, an essential component of the bacteria cell envelope. Previous work has revealed that C. difficile peptidoglycan has an unusual composition. It mostly contains 3-3 cross-links, catalyzed by enzymes called L,D-transpeptidases (Ldts) that are poorly inhibited by beta-lactams. It was therefore hypothesized that peptidoglycan polymerization by these enzymes could underpin antibiotic resistance. Here, we investigated the catalytic activity of the three canonical Ldts encoded by C. difficile (LdtCd1, LdtCd2, and LdtCd3) in vitro and explored their contribution to growth and antibiotic resistance. We show that two of these enzymes catalyze the formation of novel types of peptidoglycan cross-links using meso-diaminopimelic acid both as a donor and an acceptor, also observed in peptidoglycan sacculi. We demonstrate that the simultaneous deletion of these three genes only has a minor impact on both peptidoglycan structure and resistance to beta-lactams. This unexpected result therefore implies that the formation of 3-3 peptidoglycan cross-links in C. difficile is catalyzed by as yet unidentified noncanonical Ldt enzymes

The PHENIX Experiment at RHIC

The physics emphases of the PHENIX collaboration and the design and current status of the PHENIX detector are discussed. The plan of the collaboration for making the most effective use of the available luminosity in the first years of RHIC operation is also presented.Comment: 5 pages, 1 figure. Further details of the PHENIX physics program available at http://www.rhic.bnl.gov/phenix

Rapid and highly variable warming of lake surface waters around the globe

In this first worldwide synthesis of in situ and satellite-derived lake data, we find that lake summer surface water temperatures rose rapidly (global mean = 0.34°C decade−1) between 1985 and 2009. Our analyses show that surface water warming rates are dependent on combinations of climate and local characteristics, rather than just lake location, leading to the counterintuitive result that regional consistency in lake warming is the exception, rather than the rule. The most rapidly warming lakes are widely geographically distributed, and their warming is associated with interactions among different climatic factors—from seasonally ice-covered lakes in areas where temperature and solar radiation are increasing while cloud cover is diminishing (0.72°C decade−1) to ice-free lakes experiencing increases in air temperature and solar radiation (0.53°C decade−1). The pervasive and rapid warming observed here signals the urgent need to incorporate climate impacts into vulnerability assessments and adaptation efforts for lakes.Peer reviewe

Patterns of ash (Fraxinus excelsior L.) colonization in mountain grasslands: the importance of management practices

International audienceWoody colonization of grasslands is often associated with changes in abiotic or biotic conditions or a combination of both. Widely used as fodder and litter in the past traditional agro-pastoral system, ash (Fraxinus excelsior L.) has now become a colonizing species of mountain grasslands in the French Pyrenees. Its present distribution is dependent on past human activities and it is locally controlled by propagule pressure and abiotic conditions. However, even when all favourable conditions are met, all the potentially colonizable grasslands are not invaded. We hypothesize that management practices should play a crucial role in the control of ash colonization. From empirical field surveys we have compared the botanical composition of a set of grasslands (present and former) differing in management practices and level of ash colonization. We have displayed a kind of successional gradient positively linked to both ash cover and height but not to the age of trees. We have tested the relationships between ash presence in grassland and management types i.e. cutting and/or grazing, management intensity and some grassland communities' features i.e. total and local specific richness and species heterogeneity. Mixed use (cutting and grazing) is negatively linked to ash presence in grassland whereas grazing alone positively. Mixed use and high grazing intensity are directly preventing ash seedlings establishment, when low grazing intensity is allowing ash seedlings establishment indirectly through herbaceous vegetation neglected by livestock. Our results show the existence of a limit between grasslands with and without established ashes corresponding to a threshold in the intensity of use. Under this threshold, when ash is established, the colonization process seems to become irreversible. Ash possesses the ability of compensatory growth and therefore under a high grazing intensity develops a subterranean vegetative reproduction. However the question remains at which stage of seedling development and grazing intensity these strategies could occur

A global database of lake surface temperatures collected by in situ and satellite methods from 1985–2009

Peer reviewe

Зміни в складі населення Донбасу в 1920-1926 рр.

У статті на основі вивчення літератури та джерел досліджуються зміни в складі населення Донбасу в 1920-1926 рр. Особливу увагу приділено аналізу даних переписів 1920, 1923, 1926 рр. Показано вплив політичних чинників на зміни чисельності населення, природний та механічний приріст.In article consider the Donbas population changes in 1920-1926 years, in his storage quantity and other. Shown changes dynamics quantity of population in 1920, 1923, 1926 years. The conclusions on the nature of influence of political factoris into changes quantity of population, natural and mechanical increase