Vitamin B-12 release from P(HEMA-co-THFMA) in water and SBF: A model drug release study

A model drug release study on the ingress of water and Kokubo simulated body fluid (SBF) into poly(2-hydroxyethyl methacrylate) (THFMA) and its copolymers with tetrahydrofurfuryl methacrylate (THFMA) loaded with vitamin B-12 was undertaken over the temperature range 298-318 K. The polymers were studied as cylinders and were loaded with either 5 or 10 wt-% of the drug. The drug release from the polymers was found to follow a Fickian diffusion mechanism in the early stages of the drug release, with higher normalized release rates at higher temperatures and higher drug loadings. The normalized release rates were also found to be higher for the SBF solution than for water. The copolymer composition was found to have a significant effect on the rate of release of the drug, with the rate falling rapidly between HEMA mole fractions of 1.0 and 0.8, but for lower mole fractions of HEMA the normalized release rate decreased more slowly. This behaviour followed the trend found for the changes in the equilibrium penetrant contents for the copolymers.

Comparative agonist/antagonist responses in mutant human C5a receptors define the ligand binding site

The C terminus is responsible for all of the agonist activity of C5a at human C5a receptors (C5aRs). In this report we have mapped the ligand binding site on the C5aR using a series of agonist and antagonist peptide mimics of the C terminus of C5a as well as receptors mutated at putative interaction sites ( Ile(116), Arg(175), Arg(206), Glu(199), Asp(282), and Val(286)). Agonist peptide 1 (Phe-Lys-Pro-D-cyclohexylalanine-cyclohexylalanine-D-Arg) can be converted to an antagonist by substituting the bulkier Trp for cyclohexylalanine at position 5 ( peptide 2). Conversely, mutation of C5aR transmembrane residue Ile(116) to the smaller Ala (I116A) makes the receptor respond to peptide 2 as an agonist (Gerber, B. O., Meng, E. C., Dotsch, V., Baranski, T. J., and Bourne, H. R. (2001) J. Biol. Chem. 276, 3394 - 3400). However, a potent cyclic hexapeptide antagonist, Phe-cyclo-[Orn-Pro-D-cyclohexylalanine-Trp-Arg] ( peptide 3), derived from peptide 2 and which binds to the same receptor site, remains a full antagonist at I116AC5aR. This suggests that although the residue at position 5 might bind near to Ile(116), the latter is not essential for either activation or antagonism. Arg(206) and Arg(175) both appear to interact with the C-terminal carboxylate of C5a agonist peptides, suggesting a dynamic binding mechanism that may be a part of a receptor activation switch. Asp(282) has been previously shown to interact with the side chain of the C-terminal Arg residue, and Glu(199) may also interact with this side chain in both C5a and peptide mimics. Using these interactions to orient NMR-derived ligand structures in the binding site of C5aR, a new model of the interaction between peptide antagonists and the C5aR is presented.

Developmental vitamin D (DVD) deficiency in the rat alters adult behaviour independently of HPA function

Developmental vitamin D deficiency (DVD) has been shown to alter the orderly pattern of brain development. Even though the period of vitamin D deficiency is restricted to gestation this is sufficient to induce behavioural abnormalities in the adult offspring consistent with those seen in many animal models of schizophrenia. Given that some of these behavioural alterations could also be an indirect result of either impaired maternal hypothalamic pituitary axis (HPA) function (which in turn could influence maternal care) or the result of a permanent alteration in HPA function in the adult offspring we have examined HPA status in both maternal animals and adult offspring. In this study we have established that HPA function is normal in the maternally vitamin D deficient rat. We replicate the behavioural phenotype of hyperlocomotion whilst establishing that HPA function is also unchanged in the adult mate offspring. We conclude that the behavioural alterations induced by DVD deficiency are due to some adverse event in brain development rather than via an alteration in stress response. (c) 2006 Elsevier Ltd. All rights reserved.

Vitamin D action and regulation of bone remodeling: Suppression of osteoclastogenesis by the mature osteoblast

Vitamin D acts through the immature osteoblast to stimulate osteoclastogenesis. Transgenic elevation of VDR in mature osteoblasts was found to inhibit osteoclastogenesis associated with an altered OPG response. This inhibition was confined to cancellous bone. This study indicates that vitamin D-mediated osteoclastogenesis is regulated locally by OPG production in the mature osteoblast.

In vivo vitamin C supplementation increases phosphoinositol transfer protein expression in peripheral blood mononuclear cells from healthy individuals

Ascorbate can act as both a reducing and oxidising agent in vitro depending on its environment. It can modulate the intracellular redox environment of cells and therefore is predicted to modulate thiol-dependent cell signalling and gene expression pathways. Using proteomic analysis of vitamin C-treated T cells in vitro, we have previously reported changes in expression of five functional protein groups associated with signalling, carbohydrate metabolism, apoptosis, transcription and immune function. The increased expression of the signalling molecule phosphatidylinositol transfer protein (PITP) was also confirmed using Western blotting. Herein, we have compared protein changes elicited by ascorbate in vitro, with the effect of ascorbate on plasma potassium levels, on peripheral blood mononuclear cell (PBMC) apoptosis and PITP expression, in patients supplemented with vitamin C (0-2 g/d) for up to 10 weeks to investigate whether in vitro model systems are predictive of in vivo effects. PITP varied in expression widely between subjects at all time-points analysed but was increased by supplementation with 2 g ascorbate/d after 5 and 10 weeks. No effects on plasma potassium levels were observed in supplemented subjects despite a reduction of K+ channel proteins in ascorbate-treated T cells in vitro. Similarly, no effect of vitamin C supplementation on PBMC apoptosis was observed, whilst ascorbate decreased expression of caspase 3 recruitment domain protein in vitro. These data provide one of the first demonstrations that proteomics may be valuable in developing predictive markers of nutrient effects in vivo and may identify novel pathways for studying mechanisms of action in vivo.

Toward the discovery of vaccine adjuvants:coupling in silico screening and in vitro analysis of antagonist binding to human and mouse CCR4 receptors

Background Adjuvants enhance or modify an immune response that is made to an antigen. An antagonist of the chemokine CCR4 receptor can display adjuvant-like properties by diminishing the ability of CD4+CD25+ regulatory T cells (Tregs) to down-regulate immune responses. Methodology Here, we have used protein modelling to create a plausible chemokine receptor model with the aim of using virtual screening to identify potential small molecule chemokine antagonists. A combination of homology modelling and molecular docking was used to create a model of the CCR4 receptor in order to investigate potential lead compounds that display antagonistic properties. Three-dimensional structure-based virtual screening of the CCR4 receptor identified 116 small molecules that were calculated to have a high affinity for the receptor; these were tested experimentally for CCR4 antagonism. Fifteen of these small molecules were shown to inhibit specifically CCR4-mediated cell migration, including that of CCR4+ Tregs. Significance Our CCR4 antagonists act as adjuvants augmenting human T cell proliferation in an in vitro immune response model and compound SP50 increases T cell and antibody responses in vivo when combined with vaccine antigens of Mycobacterium tuberculosis and Plasmodium yoelii in mice.

Vitamin E-stabilised UHMWPE for orthopaedic implants:quantitative determination of vitamin E and characterisation of its transformation products

The fate of vitamin E and the formation and identification of its transformation products were investigated at different stages of the manufacturing process of commercially produced cross-linked (by γ-irradiation) UHMWPE stabilised with vitamin E (vitamin E infused-post irradiation) used for tibia-components (as articulating surfaces) in total knee arthroplasty (total knee replacement). Vitamin E (α-tocopherol) and its transformation products were extracted from microtomed Tibia films and the different products were separated, isolated, purified using high performance liquid chromatography (HPLC), and characterised by spectroscopic methods and LC-MS. The amount of vitamin E and that of the products formed in the different Tibia samples and in their extracts were also quantified using FTIR and HPLC analysis and calibration curves. Thorough analysis of the Tibia extracts has shown that a number of vitamin E transformation products were formed at different concentrations at two selected stages of the implant manufacturing process that is before and after sterilisation by γ-irradiation. The identified products were found to correspond mainly to different stereoisomeric forms of a small number of vitamin E transformation products. Most of the observed products were of dimeric and trimeric nature with their identity confirmed through a detailed study of their spectral and chromatographic characteristics. It was found that the products of vitamin E, prior to the sterilisation step but after the crosslinking and doping of vitamin E, were mainly the dihydroxydimers and trimers (Tibia samples at this stage are referred to as “Tibia-VEPE”). After sterilisation and completion of the manufacturing process, additional dimers of vitamin E were also formed (Tibia samples at this stage are referred to as ‘Tibia-VEPE-Sterile’), Furthermore, two tocopherol-derived aldehydes (aldehyde 5-formyl-γ-tocopherol and aldehyde 7-formyl-γ-tocopherol) were also formed but at very low concentrations especially in the Tibia-VEPE-Sterile samples. The question of whether vitamin E becomes chemically reacted (grafted) onto the polymer matrix during the manufacturing process of the Tibia is also addressed.

An incident at sea: The historic combat between U.S. Navy Blimp K-74 and U-Boat 134

This thesis studies the historic encounter between United States Navy airship K-74 and Nazi submarine U-134 in World War II. The Battle of the Atlantic is examined through case study of this one U-boat and its voyage. In all things except her fight with the American blimp, the patrol was perfectly typical. Looked at from start to finish, both her reports and the reports of the Allies encountered, many realities of the war can be studied. U-134 sailed to attack shipping between Florida and Cuba. She was challenged by the attack of United States Navy airship K-74 over the Florida Straits. It is the only documented instance of battle between two such combatants in history. That merits attention. Thesis finding disprove historian William Eliot Morison’s contention that the K-74 airship bombs were not dropped and did not damage the U-boat. Study of this U-boat and its antagonist broadens our understanding of the Battle of the Atlantic. It is a contribution to our knowledge of military, naval, aviation, and local history.

Seasonal changes in Vitamin D-effective UVB availability in Europe and associations with population serum 25-Hydroxyvitamin D

Low vitamin D status is common in Europe. The major source of vitamin D in humans is ultraviolet B (UVB)-induced dermal synthesis of cholecalciferol, whereas food sources are believed to play a lesser role. Our objectives were to assess UVB availability (Jm−2) across several European locations ranging from 35° N to 69° N, and compare these UVB data with representative population serum 25-hydroxyvitamin D (25(OH)D) data from Ireland (51–54° N), Iceland (64° N) and Norway (69° N), as exemplars. Vitamin D-effective UVB availability was modelled for nine European countries/regions using a validated UV irradiance model. Standardized serum 25(OH)D data was accessed from the EC-funded ODIN project. The results showed that UVB availability decreased with increasing latitude (from 35° N to 69° N), while all locations exhibited significant seasonal variation in UVB. The UVB data suggested that the duration of vitamin D winters ranged from none (at 35° N) to eight months (at 69° N). The large seasonal fluctuations in serum 25(OH)D in Irish adults was much dampened in Norwegian and Icelandic adults, despite considerably lower UVB availability at these northern latitudes but with much higher vitamin D intakes. In conclusion, increasing the vitamin D intake can ameliorate the impact of low UVB availability on serum 25(OH)D status in Europe.

Risk Factors for Maternal Vitamin D Deficiency within the United Arab Emirates

Introduction: Vitamin D deficiency during pregnancy is a public health problem and it has been associated with negative pregnancy outcomes for both mothers and infants. Aim: To estimate the prevalence of vitamin D deficiency in pregnant women in the United Arab Emirates (UAE) and to identify the contribution of risk factors to the 25(OH)D levels. Methods: It is a cross-sectional study in which vitamin D levels of 1088 adult pregnant women were assessed. Information on vitamin D intake was available in a sub-sample of 266 women. Results: The mean serum 25(OH)D was 26.2 nmol/L (95% CI 25.2-27.1 range 5-129.1 nmol/L) with 69% of women being vitamin D deficient (<30 nmol/L). In the bivariate analysis, showed that no predictors could have been indicated as no values exceeded significance (p<0.2). Stepwise multiple linear regression analysis could not be applied to identify predictors of vitamin D levels as no values exceeded p=0.2. Conclusion: Due to the high prevalence of vitamin deficiency in UAE, there is an urge for interventions focusing on supplementation, fortification and diet diversity for preventing health consequences during a critical period of development.

PREVALENCE AND PREDICTORS OF VITAMIN A DEFICIENCY AMONG INFANTS IN WESTERN KENYA USING A CROSS-SECTIONAL ANALYSIS

Vitamin A (VA) deficiency (VAD) is a major nutritional public health problem among children under-5-years-old in the developing world including Kenya. A community-based cross-sectional survey among 1,630 children (aged 6-23 mos) was undertaken in Western Kenya. A questionnaire was administered to collect demographic, socio-economic and dietary intake information. Prevalence of low retinol-binding protein (RBP) concentrations was assessed using Dried Blood Spot (DBS) methodology. Analysis of RBP was carried out using rapid enzyme immunoassay (EIA) and C-reactive protein (CRP) was carried out using enzyme linked immunosorbent assay (ELISA) to estimate VA and sub-clinical inflammation statuses, respectively. Values were adjusted for influence of inflammation using CRP (CRP >5 mg/L) and population prevalence of VAD (RBP <0.825 μmol/L, biologically equivalent to 0.70 μmol/L retinol) estimated. Anthropometric data gave three indices: stunting, wasting and underweight—all of which took age and sex into consideration. Mean (geometric± SD) concentration of RBP was adequate (1.56±0.79μmol/L) but the inflammation-adjusted mean (±SE) prevalence of VAD was high (20.1±1.1%) in this population. The level of CRP was within normal range (1.06±4.95 mg/L) whilst 18.4±0.9% of the children had subclinical inflammation (CRP>5 mg/L). Intake of VA capsule (VAC) by a child was a predictor of VAD with children who have not taken VA during the past 1 year prior to the survey having a 30% increased risk of VAD (OR (CI): 1.3 (1.1-1.7); p=0.025. Additionally, age of the child was a predictor with older children (18-23 mos) having a 30 % increased risk of VAD (OR (CI): 1.3 (1.1-1.9); p=0.035); the caretaker’s knowledge on VA and nutrition was also a predictor of VAD with children whose caretaker’s had poor knowledge having a 40 % increased risk of VAD (OR (CI): 1.4 (1.0-1.9); p=0.027. A child’s district of residence was also a significant predictor of VAD. Prevalence of VAD in this sample of infants was high. Predictors of VAD included child intake of VAC in the last 1 year before the survey, older children, children whose caretakers had poor VA and nutritional knowledge and a child’s district of residence. There is a need to improve knowledge on nutrition and VA of caretakers; undertake a targeted VAC distribution, particularly in children older than 1 year and above and use a sustainable food-based intervention in the areas with severe VAD.

Taurine Supplementation Increases K(atp) Channel Protein Content, Improving Ca2+ Handling And Insulin Secretion In Islets From Malnourished Mice Fed On A High-fat Diet.

Pancreatic β-cells are highly sensitive to suboptimal or excess nutrients, as occurs in protein-malnutrition and obesity. Taurine (Tau) improves insulin secretion in response to nutrients and depolarizing agents. Here, we assessed the expression and function of Cav and KATP channels in islets from malnourished mice fed on a high-fat diet (HFD) and supplemented with Tau. Weaned mice received a normal (C) or a low-protein diet (R) for 6 weeks. Half of each group were fed a HFD for 8 weeks without (CH, RH) or with 5% Tau since weaning (CHT, RHT). Isolated islets from R mice showed lower insulin release with glucose and depolarizing stimuli. In CH islets, insulin secretion was increased and this was associated with enhanced KATP inhibition and Cav activity. RH islets secreted less insulin at high K(+) concentration and showed enhanced KATP activity. Tau supplementation normalized K(+)-induced secretion and enhanced glucose-induced Ca(2+) influx in RHT islets. R islets presented lower Ca(2+) influx in response to tolbutamide, and higher protein content and activity of the Kir6.2 subunit of the KATP. Tau increased the protein content of the α1.2 subunit of the Cav channels and the SNARE proteins SNAP-25 and Synt-1 in CHT islets, whereas in RHT, Kir6.2 and Synt-1 proteins were increased. In conclusion, impaired islet function in R islets is related to higher content and activity of the KATP channels. Tau treatment enhanced RHT islet secretory capacity by improving the protein expression and inhibition of the KATP channels and enhancing Synt-1 islet content.

Unfavorable Outcomes During Treatment Of Multiple Sclerosis With High Doses Of Vitamin D.

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