Kinetic Resolution in Asymmetric Epoxidation using Iminium Salt Catalysis

The first reported examples of kinetic resolution in epoxidation reactions using iminium salt catalysis are described, providing up to 99% ee in the epoxidation of racemic cis-chromenes

Vitamin D status is associated with early markers of cardiovascular disease in prepubertal children

Background: The associations of 25-hydroxyvitamin D [25(OH)D], non-high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL), and related markers of early cardiovascular disease (CVD) are unclear in prepubertal children. Objective: To investigate the association of 25(OH)D with markers of CVD. The hypothesis was that 25(OH)D would vary inversely with non-HDL-C. Subjects and methods: A prospective cross-sectional study of children (n=45; 26 males, 19 females) of mean age 8.3 ± 2.5 years to investigate the relationships between 25(OH)D and glucose, insulin, high-sensitivity C-reactive protein, and lipids. Vitamin D deficiency was defined as 25(OH)D/mL; overweight as body mass index (BMI) ≥ 85 th but \u3c95th \u3epercentile; and obesity as BMI \u3e95th percentile. Results: Twenty subjects (44.4%) had BMI30 ng/mL. Patients with 25(OH)D of/mL had significantly elevated non-HDL-C (136.08 ± 44.66 vs. 109.88 ± 28.25, p=0.025), total cholesterol (TC)/HDL ratio (3.89 ± 1.20 vs. 3.21 ± 0.83, p=0.042), and triglycerides (TG) (117.09 ± 71.27 vs. 73.39 ± 46.53, p=0.024), while those with 25(OH)D of \u3e30 ng/mL had significantly lower non-HDL-C, TC/HDL, TG, and LDL (82.40 ± 18.03 vs. 105.15 ± 28.38, p=0.006). Multivariate analysis showed significant inverse correlations between 25(OH)D and non-HDL cholesterol (β=-0.337, p=0.043), and TC/HDL ratio (β=-0.339, p=0.028), and LDL (β=-0.359, p=0.016), after adjusting for age, race, sex, BMI, and seasonality. Conclusions: Vitamin D varied inversely with non-HDL, TC/HDL, and LDL. A 25(OH)D level of 30 ng/mL is associated with optimal cardioprotection in children

Alaskan Marine Transgressions Record Out-of-Phase Arctic Ocean Glaciation During the Last Interglacial

Ongoing climate change focuses attention on the Arctic cryosphere’s responses to past and future climate states. Although it is now recognized the Arctic Ocean Basin was covered by ice sheets and their associated floating ice shelves several times during the Late Pleistocene, the timing and extent of these polar ice sheets remain uncertain. Here we relate a relict barrier-island system on the Beaufort Sea coast of northern Alaska to the isostatic effects of a previously unrecognized ice shelf grounded on the adjacent continental shelf. A new suite of optically stimulated luminescence dates show that this barrier system formed during one or more marine transgressions occurring late in Marine Isotope Stage 5 (MIS 5) between 113 ka and 71 ka. Because these transgressions occurred after the warmest part of the last interglacial (ca. 123 ka) and did not coincide with the global eustatic sea-level maximum during MIS 5e, this indicates Arctic ice sheets developed out-of-phase with lower-latitude sectors of the Laurentide and Fennoscandian ice sheets. We speculate that Arctic ice sheets began development during full interglacial conditions when abundant moisture penetrated to high latitudes, and low summer insolation favored glacier growth. These ice sheets reached their full extents at interglacial-glacial transitions, then wasted away at the heights of mid-latitude glaciations because of moisture limitations

Hepatic dysfunction is associated with vitamin D deficiency and poor glycemic control in diabetes mellitus

Background/Aims: The effect of the rising prevalence of nonalcoholic fatty liver disease on the 25-hydroxylation of pre-vitamin D in the liver, and consequent glycemic control in children with diabetes mellitus is not known. Our aim was to determine whether mild hepatic dysfunction was associated with impaired 25-hydroxylation of pre-vitamin D, and if this vitamin D deficiency was associated with impaired glycemic control in children and adolescents with type 1 diabetes (TIDM) and type 2 diabetes (T2DM). Methods: We analyzed simultaneously measured HbA1c, ALT, AST, and 25OHD levels and clinical parameters in 121 children and adolescents with T1DM (n=81) and T2DM (n=40). The subjects, ages 11–21 years, all had diabetes of \u3e6 months duration. Multivariate linear regression was used to analyze the associations, while comparisons between subgroups were made using two-tailed Student’s t-test. Results: Vitamin D deficiency (25OHD/mL (37.5 nmol/L) was more prevalent in T2DM patients (47.5%) compared to T1DM patients (18.5%). Subjects with T2DM had significantly elevated transaminases (AST 39.3±2.0 vs. 22.4±1.4, p Conclusions: The association of elevated ALT with vitamin D deficiency suggests that hepatic dysfunction could impair vitamin D metabolism and negatively impact glycemic control in youth with T2DM

Cutaneous microvascular reactivity in Charcot neuroarthropathy : a systematic review and meta-analysis

Background: To systematically evaluate the literature investigating the relationship between cutaneous microvascular reactivity in the foot of adults with diabetes-related Charcot neuroarthropathy compared to a non-Charcot adult control group. Methods: A systematic search was conducted to June 2021 using the biomedical databases EBSCO Megafile Ultimate, Cochrane Library and EMBASE. Original research conducting comparative investigation of cutaneous microvascular reactivity in the foot of adults with diabetes and any pattern of acute or chronic Charcot neuroarthropathy and any non-Charcot adult control groups were included. A modified Critical Appraisal Skills Programme tool was used for quality appraisal. Cutaneous microvascular reactivity in diabetes-related Charcot neuroarthropathy data were synthesised and meta-analysis conducted where possible. Results: The search strategy identified 1,684 articles, with seven eligible for inclusion. Included studies used various methodologies and equipment to assess cutaneous microvascular reactivity in 553 participants (162 with Charcot neuroarthropathy). Cutaneous microvascular reactivity in Charcot neuroarthropathy groups was impaired compared to uncomplicated diabetes groups. Meta-analysis investigating the difference in response to thermal hyperaemia demonstrated a significant difference in cutaneous microvascular reactivity between Charcot neuroarthropathy and peripheral neuropathy with a large, pooled effect size (SMD 1.46 95% CI: 0.89– 2.02) and low heterogeneity (I 2 = 4%, T 2 = 0.01) indicating that the cutaneous microvascular response is more impaired in peripheral neuropathy than in Charcot neuroarthropathy. Conclusions: Charcot neuroarthropathy is associated with greater cutaneous microvascular reactivity in the periphery relative to diabetes cohorts with diabetes-related peripheral neuropathy alone. It is unknown if this occurs prior to, or as a result of, Charcot neuroarthropathy

Remote sensing-based statistical approach for defining drained lake basins in a continuous Permafrost region, North Slope of Alaska

Lake formation and drainage are pervasive phenomena in permafrost regions. Drained lake basins (DLBs) are often the most common landforms in lowland permafrost regions in the Arctic (50% to 75% of the landscape). However, detailed assessments of DLB distribution and abundance are limited. In this study, we present a novel and scalable remote sensing-based approach to identifying DLBs in lowland permafrost regions, using the North Slope of Alaska as a case study. We validated this first North Slope-wide DLB data product against several previously published sub-regional scale datasets and manually classified points. The study area covered \u3e71,000 km2, including a \u3e39,000 km2 area not previously covered in existing DLB datasets. Our approach used Landsat-8 multispectral imagery and ArcticDEM data to derive a pixel-by-pixel statistical assessment of likelihood of DLB occurrence in sub-regions with different permafrost and periglacial landscape conditions, as well as to quantify aerial coverage of DLBs on the North Slope of Alaska. The results were consistent with previously published regional DLB datasets (up to 87% agreement) and showed high agreement with manually classified random points (64.4–95.5% for DLB and 83.2– 95.4% for non-DLB areas). Validation of the remote sensing-based statistical approach on the North Slope of Alaska indicated that it may be possible to extend this methodology to conduct a comprehensive assessment of DLBs in pan-Arctic lowland permafrost regions. Better resolution of the spatial distribution of DLBs in lowland permafrost regions is important for quantitative studies on landscape diversity, wildlife habitat, permafrost, hydrology, geotechnical conditions, and high-lat-itude carbon cycling

Non-invasive pneumococcal pneumonia due to vaccine serotypes: A systematic review and meta-analysis

BackgroundNon-invasive pneumococcal pneumonia causes significant morbidity and mortality in older adults. Understanding pneumococcal sero-epidemiology in adults ≥50 years is necessary to inform vaccination policies and the updating of pneumococcal vaccines.MethodsWe conducted a systematic review and random-effects meta-analysis to determine the proportion of community-acquired pneumonia (CAP) in people ≥50 years due to pneumococcus and the proportion caused by pneumococcal vaccine serotypes. We searched MEDLINE, EMBASE and PubMed from 1 January 1990 to 30 March 2021. Heterogeneity was explored by subgroup analysis according to a) patient group (stratified versus age) and depth of testing, b) detection/serotyping method, and c) continent. The protocol is registered with PROSPERO (CRD42020192002).FindingsTwenty-eight studies were included (34,216 patients). In the period 1–5 years after introduction of childhood PCV10/13 immunisation, 18% of CAP cases (95% CI 13–24%) were attributable to pneumococcus, with 49% (43–54%) of pneumococcal CAP due to PCV13 serotypes. The estimated proportion of pneumococcal CAP was highest in one study that used 24-valent serotype-specific urinary-antigen detection (ss-UAD)(30% [28–31%]), followed by studies based on diagnostic serology (28% [24–33%]), PCR (26% [15–37%]), ss-UAD14 (17% [13–22%]), and culture alone (14% [10–19%]). A higher estimate was observed in Europe (26% [21–30%] than North America (11% [9–12%](p<0·001). PCV13-serotype estimates were also influenced by serotyping methods.InterpretationNon-invasive pneumococcal CAP and vaccine-type pneumococcal CAP remains a burden in older adults despite widespread introduction of pneumococcal infant immunisation. Studies heavily reliant on ss-UADs restricted to vaccine-type serotypes may overestimate the proportion of potentially vaccine-preventable pneumococcal pneumonia. Sero-epidemiological data from low-income countries are lacking

Dynamics of Arctic Permafrost Coasts in the 21st Century

Climate warming is particularly pronounced in the Arctic with temperatures rising twice as much as in the rest of the world. It seems natural that this warming has profound effects on the speed of erosion of Arctic coasts, since the majority consists of permafrost, composed of unlithified material and hold together by ice. Permafrost stores approximately 1307 Gt of carbon, which is almost 60 % more than currently being contained in the atmosphere. Understanding the main drivers and dynamics of permafrost coastal erosion is of global relevance, especially since floods and erosion are both projected to intensify. However, the assessment of the impacts of climate warming on Arctic coasts is impaired by little data availability. We reviewed relevant scientific literature on changing dynamics of Arctic coast, potential drivers of these changes and the impacts on the human and natural environment. We provide a comprehensive overview over the state of the art and share our thoughts on how we envision potential pathways of future Arctic coastal research. We found that the overwhelming majority of all studied Arctic coasts is erosive and that in most cases erosion rates per year are increasing, threatening coastal settlements, infrastructure, cultural sites and archaeological remains. The impacts on the natural environment are also manifold and reach from changing sediment fluxes which limit light availability in the water column to a higher input of carbon and nutrients into the nearshore zone with the potential to influence food chains

A potential role for adjunctive vitamin D therapy in the management of weight gain and metabolic side effects of second-generation antipsychotics

Second-generation antipsychotic (SGA) medications introduced about 20 years ago are increasingly used to treat psychiatric illnesses in children and adolescents. There has been a five-fold increase in the use of these medications in U.S. children and adolescents in the past decade. However, there has also been a parallel rise in the incidence of side effects associated with these medications, such as obesity, dyslipidemia, insulin resistance, and diabetes mellitus. Despite the severity of these complications and their financial impact on the national healthcare budget, there is neither a clear understanding of the mechanisms contributing to these side effects nor the best ways to address them. Studies that examined lifestyle modification and pharmaceutical agents have yielded mixed results. Therefore, clinical studies using agents, such as vitamin D, which are inexpensive, readily available, with low side effects profile, and have mechanisms to counteract the metabolic side effects of SGA agents, are warranted. Vitamin D is a prohormone with skeletal and extraskeletal properties that could potentially reduce the severity of these metabolic side effects. Its role as an adjunctive therapy for the management of metabolic side effects of SGA agents has not been adequately studied. Effective strategies to curb these side effects will improve the overall health of youths with psychiatric illnesses who receive SGAs. Herein we present a pilot study on the use of vitamin D in patients on treatment with SGAs

Comparing coastal dynamics between two geomorphologically distinct permafrost affected coastlines in NW Alaska

Arctic clastic coastlines are some of the most dynamic in the world and have a large impact on cultural and natural resources. Sea ice plays an important role in the erosion and accretion dynamics of these coastlines, and sea ice cover is currently declining at >10% per decade. As a result of declining sea ice cover and an increase in the duration of open water days in the Arctic Ocean, we need to know more about coastal processes in polar seas, specifically how sea ice decline changes coastal processes, the rate at which such coastal changes can occur, and how the effects of declining sea ice interacts with local coastline characteristics including wave fetch, bathymetry, permafrost properties onshore, and pre-existing coastal geomorphology. To assess the influence of sea ice decline on permafrost coastal dynamics we selected two segments of the coastline in NW Alaska with contrasting geography, surficial geology and geomorphology. Study site A, Cape Krusenstern National Monument (CAKR), has a wave-dominated, west- to south-west facing, coarseclastic shoreline. Accreted beach ridges, barrier-closed lagoons, permafrost bluffs, longshore gravel bars, and gravelly beaches characterize coastal geomorphology. Study site B, the Bering Land Bridge National Park and Preserve (BELA), has a north-facing coastline with a shoreline characterized by yedoma and thermokarst basin permafrost bluffs, aggrading spits, sandy barrier islands, and open lagoons. To establish rates of coastal change and identify key geomorphological processes, we digitally mapped the shoreline of both study areas using aerial photographs (1-meter resolution or better) and sub-meter resolution World View-2 satellite imagery from 2003 and 2014, respectively. We compared our data to the results of previous studies based on imagery taken between 1950 and 2003 (Lestak et al., 2010). To better understand the relationship between geomorphology and rates of change, we established geomorphological landform classes for both study areas. We mapped coastal changes within a subset of each study area, using sub meter resolution imagery, over annual time steps to help us better quantify variations in the rate of event driven coastline change. Mapping results for the period 2003 to 2014 suggest a change in erosion rates within both study sites. Erosion rates for the period 1950 to 2003 in BELA and CAKR were -0.12 m/yr and -0.98 m/yr respectively, where the negative signs indicate shoreline retreat (Gorokhovich and Leiserowiz, 2012). These rates, for the period between 2003 and 2014, increased in CAKR to -0.86 and decreased in BELA to -0.69 m/yr. Rates of erosion were found to vary according to geomorphology, with overwash fans in BELA exhibiting the highest rates of change at -1.3 m/yr. Significant changes in geomorphology were observed for this time period including the development of a 200-meter long spit in CAKR, degradation of ice wedges on upland yedoma bluffs in BELA, and the infilling of numerous barrier island ponds due to overwash events in BELA. Our results illustrate the complexity of coastal responses along Arctic coastlines even within close proximity. To ensure robust projections of future coastal change, further mapping and analysis at intraannual and sub-meter spatial resolution is necessary to firmly tie together cause and effect of arctic coastal processes with a changing climate. References: 1. Gorokhovich, Y., Leiserowiz, A., 2012. Historical and Future Coastal Changes in Northwest Alaska. J. Coast. Res. 28, 174–186. 2. Lestak, L.R., Manley, W.F., Parrish, E.G., 2010. Digital Shoreline Analysis of Coastal Change in Bering Land Bridge NP (BELA) and Cape Krusenstern NM (CAKR), Northwest Alaska: Fairbanks, AK: National Park Service, Arctic Network I&M Program. Geospatial Dataset-2184176