Skeletal muscle and the maintenance of vitamin d status

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. Vitamin D, unlike the micronutrients, vitamins A, E, and K, is largely obtained not from food, but by the action of solar ultraviolet (UV) light on its precursor, 7-dehydrocholesterol, in skin. With the decline in UV light intensity in winter, most skin production of vitamin D occurs in summer. Since no defined storage organ or tissue has been found for vitamin D, it has been assumed that an adequate vitamin D status in winter can only be maintained by oral supplementation. Skeletal muscle cells have now been shown to incorporate the vitamin D-binding protein (DBP) from blood into the cell cytoplasm where it binds to cytoplasmic actin. This intracellular DBP provides an array of specific binding sites for 25-hydroxyvitamin D (25(OH)D), which diffuses into the cell from the extracellular fluid. When intracellular DBP undergoes proteolytic breakdown, the bound 25(OH)D is then released and diffuses back into the blood. This uptake and release of 25(OH)D by muscle accounts for the very long half-life of this metabolite in the circulation. Since 25(OH)D concentration in the blood declines in winter, its cycling in and out of muscle cells appears to be upregulated. Parathyroid hormone is the most likely factor enhancing the repeated cycling of 25(OH)D between skeletal muscle and blood. This mechanism appears to have evolved to maintain an adequate vitamin D status in winter

The effect of parathyroid hormone on the uptake and retention of 25-hydroxyvitamin D in skeletal muscle cells

© 2017 Elsevier Ltd Data from our studies, and those of others, support the proposal that there is a role for skeletal muscle in the maintenance of vitamin D status. We demonstrated that skeletal muscle is able to internalise extracellular vitamin D binding protein, which then binds to actin in the cytoplasm, to provide high affinity binding sites which accumulate 25-hydroxyvitamin D3 (25(OH)D3) [1]. This study investigated the concentration- and time-dependent effects of parathyroid hormone (PTH) on the capacity of muscle cells to take up and release 3H-25(OH)D3. Uptake and retention studies for 3H-25(OH)D3 were carried out with C2C12 cells differentiated into myotubes and with primary mouse muscle fibers as described [1]. The presence of PTH receptors on mouse muscle fibers was demonstrated by immunohistochemistry and PTH receptors were detected in differentiated myotubes, but not myoblasts, and on muscle fibers by Western blot. Addition of low concentrations of vitamin D binding protein to the incubation media did not alter uptake of 25(OH)D3. Pre-incubation of C2 myotubes or primary mouse muscle fibers with PTH (0.1 to 100 pM) for 3 h resulted in a concentration-dependent decrease in 25(OH)D3 uptake after 4 or 16 h. These effects were significant at 0.1 or 1 pM PTH (p \u3c 0.001) and plateaued at 10 pM, with 25(OH)D3 uptake reduced by over 60% (p \u3c 0.001) in both cell types. In C2 myotubes, retention of 25(OH)D3 was decreased after addition of PTH (0.1 to 100 pM) in a concentration-dependent manner by up to 80% (p \u3c 0.001) compared to non-PTH treated-C2 myotubes. These data show that muscle uptake and retention of 25(OH)D3 are modulated by PTH, a physiological regulator of mineral homeostasis, but the cell culture model may not be a comprehensive reflection of vitamin D homeostatic mechanisms in whole animals

Access to patients' clinical healthcare records: inclusion for community pharmacists in NHS Tayside.

The 2020 Workforce Vision in Scotland envisages 'making more and better use of technology ....to increase access to services and improve efficiency' across the healthcare interface. Services offered by community pharmacy remain limited by lack of shared access to patients' clinical information. In Scotland, every patient has a unique identifier, their CHI (community health index), which facilitates identification of/searching for patient records. The aim of this research was to explore the experiences of community pharmacists granted clinical portal access to patients' records

Methodological approaches to determining the marine radiocarbon reservoir effect

The marine radiocarbon reservoir effect is an offset in 14C age between contemporaneous organisms from the terrestrial environment and organisms that derive their carbon from the marine environment. Quantification of this effect is of crucial importance for correct calibration of the <sup>14</sup>C ages of marine-influenced samples to the calendrical timescale. This is fundamental to the construction of archaeological and palaeoenvironmental chronologies when such samples are employed in <sup>14</sup>C analysis. Quantitative measurements of temporal variations in regional marine reservoir ages also have the potential to be used as a measure of process changes within Earth surface systems, due to their link with climatic and oceanic changes. The various approaches to quantification of the marine radiocarbon reservoir effect are assessed, focusing particularly on the North Atlantic Ocean. Currently, the global average marine reservoir age of surface waters, R(t), is c. 400 radiocarbon years; however, regional values deviate from this as a function of climate and oceanic circulation systems. These local deviations from R(t) are expressed as +R values. Hence, polar waters exhibit greater reservoir ages (δR = c. +400 to +800 <sup>14</sup>C y) than equatorial waters (δR = c. 0 <sup>14</sup>C y). Observed temporal variations in δR appear to reflect climatic and oceanographic changes. We assess three approaches to quantification of marine reservoir effects using known age samples (from museum collections), tephra isochrones (present onshore/offshore) and paired marine/terrestrial samples (from the same context in, for example, archaeological sites). The strengths and limitations of these approaches are evaluated using examples from the North Atlantic region. It is proposed that, with a suitable protocol, accelerator mass spectrometry (AMS) measurements on paired, short-lived, single entity marine and terrestrial samples from archaeological deposits is the most promising approach to constraining changes over at least the last 5 ky BP

The relationship between deprivation, tumour stage and the systemic inflammatory response in patients with primary operable breast cancer

The extent of deprivation (Carstairs deprivation index) was directly associated with the magnitude of the systemic inflammatory response (reduced albumin and elevated C-reactive protein, P<0.01) in patients with primary operable breast cancer (n=314). Deprivation was not associated with age, tumour size, tumour type, grade, and the proportion of patients with involved lymph nodes and oestrogen receptor status

Pseudogene accumulation in the evolutionary histories of Salmonella enterica serovars Paratyphi A and Typhi

<p>Abstract</p> <p>Background</p> <p>Of the > 2000 serovars of <it>Salmonella enterica </it>subspecies I, most cause self-limiting gastrointestinal disease in a wide range of mammalian hosts. However, <it>S. enterica </it>serovars Typhi and Paratyphi A are restricted to the human host and cause the similar systemic diseases typhoid and paratyphoid fever. Genome sequence similarity between Paratyphi A and Typhi has been attributed to convergent evolution via relatively recent recombination of a quarter of their genomes. The accumulation of pseudogenes is a key feature of these and other host-adapted pathogens, and overlapping pseudogene complements are evident in Paratyphi A and Typhi.</p> <p>Results</p> <p>We report the 4.5 Mbp genome of a clinical isolate of Paratyphi A, strain AKU_12601, completely sequenced using capillary techniques and subsequently checked using Illumina/Solexa resequencing. Comparison with the published genome of Paratyphi A ATCC9150 revealed the two are collinear and highly similar, with 188 single nucleotide polymorphisms and 39 insertions/deletions. A comparative analysis of pseudogene complements of these and two finished Typhi genomes (CT18, Ty2) identified several pseudogenes that had been overlooked in prior genome annotations of one or both serovars, and identified 66 pseudogenes shared between serovars. By determining whether each shared and serovar-specific pseudogene had been recombined between Paratyphi A and Typhi, we found evidence that most pseudogenes have accumulated after the recombination between serovars. We also divided pseudogenes into relative-time groups: ancestral pseudogenes inherited from a common ancestor, pseudogenes recombined between serovars which likely arose between initial divergence and later recombination, serovar-specific pseudogenes arising after recombination but prior to the last evolutionary bottlenecks in each population, and more recent strain-specific pseudogenes.</p> <p>Conclusion</p> <p>Recombination and pseudogene-formation have been important mechanisms of genetic convergence between Paratyphi A and Typhi, with most pseudogenes arising independently after extensive recombination between the serovars. The recombination events, along with divergence of and within each serovar, provide a relative time scale for pseudogene-forming mutations, affording rare insights into the progression of functional gene loss associated with host adaptation in <it>Salmonella</it>.</p

A simple method for directional transcriptome sequencing using Illumina technology.

High-throughput sequencing of cDNA has been used to study eukaryotic transcription on a genome-wide scale to single base pair resolution. In order to compensate for the high ribonuclease activity in bacterial cells, we have devised an equivalent technique optimized for studying complete prokaryotic transcriptomes that minimizes the manipulation of the RNA sample. This new approach uses Illumina technology to sequence single-stranded (ss) cDNA, generating information on both the direction and level of transcription throughout the genome. The protocol, and associated data analysis programs, are freely available from http://www.sanger.ac.uk/Projects/Pathogens/Transcriptome/. We have successfully applied this method to the bacterial pathogens Salmonella bongori and Streptococcus pneumoniae and the yeast Schizosaccharomyces pombe. This method enables experimental validation of genetic features predicted in silico and allows the easy identification of novel transcripts throughout the genome. We also show that there is a high correlation between the level of gene expression calculated from ss-cDNA and double-stranded-cDNA sequencing, indicting that ss-cDNA sequencing is both robust and appropriate for use in quantitative studies of transcription. Hence, this simple method should prove a useful tool in aiding genome annotation and gene expression studies in both prokaryotes and eukaryotes