Collisional kinetics of non-uniform electric field, low-pressure, direct-current discharges in H2_{2}

A model of the collisional kinetics of energetic hydrogen atoms, molecules, and ions in pure H$_2$ discharges is used to predict H$_\alpha$ emission profiles and spatial distributions of emission from the cathode regions of low-pressure, weakly-ionized discharges for comparison with a wide variety of experiments. Positive and negative ion energy distributions are also predicted. The model developed for spatially uniform electric fields and current densities less than $10^{-3}$ A/m$^2$ is extended to non-uniform electric fields, current densities of $10^{3}$ A/m$^2$, and electric field to gas density ratios $E/N = 1.3$ MTd at 0.002 to 5 Torr pressure. (1 Td = $10^{-21}$ V m$^2$ and 1 Torr = 133 Pa) The observed far-wing Doppler broadening and spatial distribution of the H$_\alpha$ emission is consistent with reactions among H$^+$, H$_2^+$, H$_3^+$, and H$^-H$ ions, fast H atoms, and fast H$_2$ molecules, and with reflection, excitation, and attachment to fast H atoms at surfaces. The H$_\alpha$ excitation and H$^-$ formation occur principally by collisions of fast H, fast H$_2$, and H$^+$ with H$_2$. Simplifications include using a one-dimensional geometry, a multi-beam transport model, and the average cathode-fall electric field. The H$_\alpha$ emission is linear with current density over eight orders of magnitude. The calculated ion energy distributions agree satisfactorily with experiment for H$_2^+$ and H$_3^+$, but are only in qualitative agreement for H$^+$ and H$^-$. The experiments successfully modeled range from short-gap, parallel-plane glow discharges to beam-like, electrostatic-confinement discharges.Comment: Submitted to Plasmas Sources Science and Technology 8/18/201

Vitamin d status predicts 30 day mortality in hospitalised cats

Vitamin D insufficiency, defined as low serum concentrations of the major circulating form of vitamin D, 25 hydroxyvitamin D (25(OH)D), has been associated with the development of numerous infectious, inflammatory, and neoplastic disorders in humans. In addition, vitamin D insufficiency has been found to be predictive of mortality for many disorders. However, interpretation of human studies is difficult since vitamin D status is influenced by many factors, including diet, season, latitude, and exposure to UV radiation. In contrast, domesticated cats do not produce vitamin D cutaneously, and most cats are fed a commercial diet containing a relatively standard amount of vitamin D. Consequently, domesticated cats are an attractive model system in which to examine the relationship between serum 25(OH)D and health outcomes. The hypothesis of this study was that vitamin D status would predict short term, all-cause mortality in domesticated cats. Serum concentrations of 25(OH)D, together with a wide range of other clinical, hematological, and biochemical parameters, were measured in 99 consecutively hospitalised cats. Cats which died within 30 days of initial assessment had significantly lower serum 25(OH)D concentrations than cats which survived. In a linear regression model including 12 clinical variables, serum 25(OH)D concentration in the lower tertile was significantly predictive of mortality. The odds ratio of mortality within 30 days was 8.27 (95% confidence interval 2.54-31.52) for cats with a serum 25(OH)D concentration in the lower tertile. In conclusion, this study demonstrates that low serum 25(OH)D concentration status is an independent predictor of short term mortality in cats

Gene Expression Profiles in Human and Mouse Primary Cells Provide New Insights into the Differential Actions of Vitamin D-3 Metabolites

1α,25-Dihydroxyvitamin D3 (1α,25(OH)2D3) had earlier been regarded as the only active hormone. The newly identified actions of 25-hydroxyvitamin D3 (25(OH)D3) and 24R,25-dihydroxyvitamin D3 (24R,25(OH)2D3) broadened the vitamin D3 endocrine system, however, the current data are fragmented and a systematic understanding is lacking. Here we performed the first systematic study of global gene expression to clarify their similarities and differences. Three metabolites at physiologically comparable levels were utilized to treat human and mouse fibroblasts prior to DNA microarray analyses. Human primary prostate stromal P29SN cells (hP29SN), which convert 25(OH)D3 into 1α,25(OH)2D3 by 1α-hydroxylase (encoded by the gene CYP27B1), displayed regulation of 164, 171, and 175 genes by treatment with 1α,25(OH)2D3, 25(OH)D3, and 24R,25(OH)2D3, respectively. Mouse primary Cyp27b1 knockout fibroblasts (mCyp27b1−/−), which lack 1α-hydroxylation, displayed regulation of 619, 469, and 66 genes using the same respective treatments. The number of shared genes regulated by two metabolites is much lower in hP29SN than in mCyp27b1−/−. By using DAVID Functional Annotation Bioinformatics Microarray Analysis tools and Ingenuity Pathways Analysis, we identified the agonistic regulation of calcium homeostasis and bone remodeling between 1α,25(OH)2D3 and 25(OH)D3 and unique non-classical actions of each metabolite in physiological and pathological processes, including cell cycle, keratinocyte differentiation, amyotrophic lateral sclerosis signaling, gene transcription, immunomodulation, epigenetics, cell differentiation, and membrane protein expression. In conclusion, there are three distinct vitamin D3 hormones with clearly different biological activities. This study presents a new conceptual insight into the vitamin D3 endocrine system, which may guide the strategic use of vitamin D3 in disease prevention and treatment.Peer reviewe

Inflammatory eye reactions with bisphosphonates and other osteoporosis medications:what are the risks?

Inflammatory eye reactions (IERs) are rare but have been associated with medications to treat osteoporosis. The aim of this review is to summarize the current literature on the association between IERs and specific medications to treat osteoporosis (bisphosphonates, selective estrogen receptor modulators, strontium, denosumab and teriparatide). We cover the known epidemiology, potential pathogenic mechanisms and a resume of unanswered questions. Briefly, this review highlights that none of the existing randomized clinical trials were powered to identify these rare adverse events, and the majority of the information available is from spontaneous case reports and case series reporting associations between bisphosphonates and IERs. No case reports describe IERs after other anti-osteoporosis medications. Importantly, some case reports describe recurrence of the IER after affected patients were rechallenged with the same or another bisphosphonate, and that no reported cases resolved without discontinuation of the bisphosphonate. However, three large population-based cohort studies have shown conflicting results between osteoporosis treatments and IERs, but overall these studies suggest that IERs may actually be part of underlying inflammatory disease processes that also cause osteoporosis, rather than due to the medications used to treat osteoporosis themselves. There are no clear pathogenic mechanisms for how bisphosphonates could potentially cause IERs. However, the drug is secreted into the tears by the lacrimal gland and could cause irritation to the mucous membranes with subsequent release of inflammatory mediators, similar to the systemic response typically seen after infusion of bisphosphonates. However, in summary it is still not known whether there is a true causal association between bisphosphonates or other anti-osteoporosis medications and IERs, or whether it is confounding by indication and is actually due to underlying inflammatory diseases that cause both osteoporosis and IERs

Effets du vieillissement sur les capacités adaptatives locomotrices

The aim of this research was to better understand how gait slows with age. We analyzed the kinematic parameters of locomotion (velocity, stride length, cycle duration, and double support duration) and their interrelationships both in the slowing process due to aging and in intentional modulations of velocity. The experiments were carried out on a group of 67 elderly adults (aged 60 to 92) walking with a free gait and a fast gait. This group was compared to a young population in equivalent situations. The results show that the main characteristics of the elderly gait are the shortening of strides and the increasing of the double support phase. However, these properties seem to be due to the slowness of the elderly gait more than to more specific alterations affecting this population since identical features were also observed in the slow gait of the young subjects. Furthermore, the ability to intentionally modulate velocity observed in this study was not altered by aging. These results suggest that elderly gait can be said to be normal if one takes the velocity into account.Le but de cette recherche est de tenter de mieux comprendre comment la marche ralentit avec le vieillissement. Les paramètres cinématiques de la locomotion (vitesse, longueur d'enjambée, durée du cycle et du double appui) et leurs relations à la fois dans le ralentissement lié à l'âge et dans les modulations volontaires de vitesse ont été analysés. Les expériences ont porté sur un groupe de 67 sujets âgés (de 60 à 92 ans) et un groupe contrôle de sujets jeunes dans une marche normale et une marche rapide. Les résultats montrent que le vieillissement entraîne une diminution de la vitesse et de la longueur d'enjambée et une augmentation de la durée du double appui. Celle-ci cependant semble due plus à la lenteur qu'au vieillissement lui-même, puisque les mêmes caractéristiques ont aussi été observées dans la marche lente des sujets jeunes. Déplus la capacité de moduler volontairement sa vitesse n'est pas altérée par le vieillissement. On peut donc considérer la marche des sujets âgés comme normale, si l'on tient compte de leur vitesse.Ferrandez Anne-Marie, Durup M., Pailhous J. Effets du vieillissement sur les capacités adaptatives locomotrices. In: Enfance, n°2, 1995. Aspects actuels de recherches sur la Psychologie du Développement. pp. 147-154

Body Mass Index and Operating Times in Vascular Procedures

: Introduction: The influence of body mass index (BMI) on operating times in central and peripheral vascular surgical procedures was investigated. Report: A national cohort of Danish patients who underwent a vascular procedure between 1983 and 2012 was used for analysis. Data were analysed with pairwise comparisons of BMI groups for operating times using the independent samples Kruskall–Wallis test. Discussion: A total of 3,255 carotid endarterectomies; 6,885 central vascular procedures; and 4,488 peripheral bypasses were included for the analysis. Median operating times for carotid endarterectomy and central vascular procedures were, respectively, 5 and 15 minutes longer in obese patients than in normal weight patients. This represents a 7% and 10% increase in median operating times, respectively. Linear and multi-adjusted linear regressions were conducted adjusting for confounders, showing a significant correlation between BMI and operating time. Obesity significantly increased the operating times in carotid endarterectomy and central vascular procedures. These may have ramifications for the individual operative stress but not necessarily on logistical operation planning. Keywords: Body mass index (BMI), Obesity, Operating time, Surgery, Vascular surgical procedure