23 research outputs found
Identification of vitamin D2 metabolites and age-related changes in the 1,25-dihydroxyvitamin D3 steroid receptor in male Fischer 344 rats
No full textThe use of Fourier transform [superscript]1H NMR to characterize vitamin D[subscript]2 metabolites is described. High-resolution spectra were obtained on 5 [mu]g of material using a 300-MHz FT spectrometer. The [superscript]1H NMR spectra of a variety of both synthetic and naturally occurring vitamin D[subscript]2 metabolites resulted in the reassignment of the chemical shifts for the C-21 and C-28 methyl groups of vitamin D[subscript]2. The C-21 methyl group is now assigned to the doublet appearing at [delta]1.01, whereas the C-28 signal corresponds to the doublet at [delta]0.90. The [superscript]1H NMR spectrum was instrumental in establishing the identity of a new vitamin D[subscript]2 metabolite, 24,26-dihydroxyvitamin D[subscript]2. This unique physiological metabolite was isolated from the plasma of a vitamin D[subscript]2-toxic cow, but was also detected in rats supplemented with physiologic amounts of the vitamin. The formation of 24,26-dihydroxyvitamin D[subscript]2 represented a major pathway for further metabolism of 24-hydroxyvitamin D[subscript]2 in rats, exceeding the formation 24,25-dihydroxyvitamin D[subscript]2. Standard bioassays revealed that 24,26-dihydroxyvitamin D[subscript]2 possessed very little biological activity and likely represents a deactivation pathway for 24-hydroxyvitamin D[subscript]2;The effects of age on the intestinal and kidney 1,25-dihydroxyvitamin D[subscript]3 steroid receptor were studied in male Fischer 344 rats. There was a marked decrease in the number of intestinal receptors in old animals relative to young, but there was no discernible difference in the percentage of receptors binding to DNA-cellulose. Immunoblots only weakly identified intact intestinal receptor from older rats following DNA-cellulose chromatography. Similar amounts of young intestinal receptor were easily identified as a single band at 52 K in immunoblots. The presence of an increased endogenous protease activity in older animals was implicated. The specific binding of receptor in kidney cytosols was not different in the two age groups, but there was a significant decrease in the percentage of receptors binding to DNA-cellulose from older rats. Immunoblots of kidney preparations from either young or old rats following DNA-cellulose chromatography revealed two protein bands at 52 K and 50 K that corresponded to receptor. These results demonstrated for the first time that multiple forms of the vitamin D receptor exist in a mammalian system.</p
Effects of dietary fiber on cecal short-chain fatty acid and cecal microbiota of broiler and laying-hen chicks
No full textThis experiment was conducted to evaluate the effects of feeding dietary fiber on cecal short-chain fatty acid (SCFA) concentration and cecal microbiota of broiler and laying-hen chicks. The lower fiber diet was based on corn-soybean meal (SBM) and the higher fiber diet was formulated using corn-SBM-dried distillers grains with solubles (DDGS) and wheat bran to contain 60.0 g/kg of both DDGS and wheat bran from 1 to 12 d and 80.0 g/kg of both DDGS and wheat bran from 13 to 21 d. Diets were formulated to meet or exceed NRC nutrient requirements. Broiler and laying-hen chicks were randomly assigned to the high and low fiber diets with 11 replicates of 8 chicks for each of the 4 treatments. One cecum from 3 chicks was collected from each replicate: one cecum underwent SCFA concentration analysis, one underwent bacterial DNA isolation for terminal restriction fragment length polymorphism (TRFLP), and the third cecum was used for metagenomics analyses. There were interactions between bird line and dietary fiber for acetic acid (P = 0.04) and total SCFA (P = 0.04) concentration. There was higher concentration of acetic acid (P = 0.02) and propionic acid (P P = 0.02) and chicken line (P = 0.03). Metagenomics analyses identified differences in the relative abundance of Helicobacter pullorum and Megamonas hypermegale and the genera Enterobacteriaceae, Campylobacter, Faecalibacterium, and Bacteroides in different treatment groups. These results provide insights into the effect of dietary fiber on SCFA concentration and modulation of cecal microbiota in broiler and laying-hen chicks.This article is published as Walugembe, M., J. C. F. Hsieh, N. J. Koszewski, S. J. Lamont, M. E. Persia, and M. F. Rothschild. "Effects of dietary fiber on cecal short-chain fatty acid and cecal microbiota of broiler and laying-hen chicks." Poultry Science 94, no. 10 (2015): 2351-2359. DOI: 10.3382/ps/pev242. Posted with permission.</p
Update on vitamin D and its newer analogues: Actions and rationale for treatment in chronic renal failure
No full textUpdate on vitamin D and its newer analogues: Actions and rationale for treatment in chronic renal failure. Vitamin D is an important hormone for mineral homeostasis and the proper formation and maintenance of bone. In addition, vitamin D has broader functions in the body that expand its traditionally known role in mineral balance. In chronic renal failure, calcitriol deficiency contributes to the development and progression of secondary hyperparathyroidism, bone disorders, and altered mineral metabolism. Recent revelations of the broader role of vitamin D also suggest calcitriol deficiency may contribute to decreased cardiac and immune function in chronic renal failure patients. Research on vitamin D has led to a more complete understanding of the actions of vitamin D at the transcriptional level and with respect to the clinical use of vitamin D and its analogs to control parathyroid hormone overactivity and to replace the other D hormone-dependent actions in patients with renal failure. Limitations of vitamin D and its metabolites include hypercalcemia, hyperphosphatemia and suppression of bone turnover with the risk of adynamic bone disease. Vitamin D analogs may offer greater selectivity and potentially greater safety as compared to calcitriol because of their altered relative potency on calcium and phosphorus metabolism. This review focuses on the current understanding of the biological actions of vitamin D and its analogs and the rationale for treating patients with chronic renal failure
Comparison of 0.46% calcium diets with and without added anions with a 0.7% calcium anionic diet as a means to reduce periparturient hypocalcemia
No full textVitamin D receptor interactions with positive and negative DNA response elements: an interference footprint comparison
No full text
Effects of run-up velocity on performance, kinematics, and energy exchanges in the pole vault
No full textCopyright @ 2012 The Authors. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and 85 reproduction in any medium, provided the original author and source are credited. The article was made available through the Brunel University Open Access Publishing Fund.This study examined the effect of run-up velocity on the peak height achieved by the athlete in the pole vault and on the corresponding changes in the athlete's kinematics and energy exchanges. Seventeen jumps by an experienced male pole vaulter were video recorded in the sagittal plane and a wide range of run-up velocities (4.5-8.5 m/s) was obtained by setting the length of the athlete's run-up (2-16 steps). A selection of performance variables, kinematic variables, energy variables, and pole variables were calculated from the digitized video data. We found that the athlete's peak height increased linearly at a rate of 0.54 m per 1 m/s increase in run-up velocity and this increase was achieved through a combination of a greater grip height and a greater push height. At the athlete's competition run-up velocity (8.4 m/s) about one third of the rate of increase in peak height arose from an increase in grip height and about two thirds arose from an increase in push height. Across the range of run-up velocities examined here the athlete always performed the basic actions of running, planting, jumping, and inverting on the pole. However, he made minor systematic changes to his jumping kinematics, vaulting kinematics, and selection of pole characteristics as the run-up velocity increased. The increase in run-up velocity and changes in the athlete's vaulting kinematics resulted in substantial changes to the magnitudes of the energy exchanges during the vault. A faster run-up produced a greater loss of energy during the take-off, but this loss was not sufficient to negate the increase in run-up velocity and the increase in work done by the athlete during the pole support phase. The athlete therefore always had a net energy gain during the vault. However, the magnitude of this gain decreased slightly as run-up velocity increased
We're on a road to nowhere... new forms of work organization and national cultures
No full textThe main objective of this paper is to discuss how far the cultural environment is related to the potential that new forms of work organization, namely autonomy and teamwork, have for success. To accomplish this objective two main approaches will be used: on the one hand, the Socio-Technical Systems(STS) approach, as the main theoretical background for new forms of work organization; and on the other hand, Hofstede’s Cultural Dimensions as the theoretical model to frame the concept of national cultures. The study was developed using data from 23 EU countries. The study showed that the correlation between national cultures and new forms of work organization are significant, yet moderate. Moreover, differences in the impact of cultural dimensions on work design practices were found. The use of autonomy and teamwork can be insufficient to represent the wide variety of work design practices in STS. The same is also valid for cultural dimensions. An understanding of the cultural constraints on work design practices in EU countries can help improve organization models, furthering competitiveness.culture; work organization; autonomy; teamwork; Europe; Hofstede
Oral 25-Hydroxycholecalciferol Acts as an Agonist in the Duodenum of Mice and as Modeled in Cultured Human HT-29 and Caco2 Cells
No full text
