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At least 73 records · Page 4Linked to original sources
PubMed1985

Vitamin B12 absorption in the neonatal piglet. 3. Influence of vitamin B12-binding protein from sows' milk on uptake of vitamin B12 by microvillus membrane vesicles prepared from small intestine of the piglet.

The influence of the vitamin B12-binding protein isolated from sows' milk on the uptake of vitamin B12 was investigated using microvillus membrane vesicles prepared from the small intestine of 7- and 28-d-old piglets. Uptake of radioiodinated purified binder was also examined. The binder strongly promoted uptake of vitamin B12 at both ages; in the absence of the binder there was little uptake. The uptake mechanism was specific and operative in vesicles prepared from all regions of the small intestine. Uptake was a rapid process, exhibiting saturation kinetics, with a pH optimum at about 7.0, and dependent on the presence of magnesium or calcium ions for maximum activity. Affinity constants of the binding sites for the milk binder were determined. Competition experiments using complexes of the binder with vitamin B12 and with non-cobalamin analogues (cobinamide and Co-alpha-[2-methyladenyl]cobamide) showed that the bound analogues competed with bound vitamin B12 for uptake but with lower efficiency. Intrinsic factor also promoted vitamin B12 uptake by the vesicles but it did not compete with the milk binder for the same binding sites. It promoted uptake only in microvilli isolated from the lower third of the small intestine, and was more effective with preparations from 28-d-old piglets, whereas the milk binder was more effective with the 7-d-old piglets. Porcine gastric cobalophilin competed with the milk cobalophilin, but with lower efficiency. It was concluded that a specific transport mechanism for absorption of vitamin B12, mediated by the vitamin B12-binder in milk, exists at the intestinal brush border of neonatal piglets and strongly reinforces the developing intrinsic factor-mediated mechanism during the early days or weeks of life. It is suggested that the binder in the milk has a wider physiological significance and acts also as a 'host protective' factor and as a scavenger of adventitious vitamin B12.

Animals↗
PubMed1996

Interaction of zinc and vitamin A in rats receiving a regional diet of Manaus, Amazonas, Brazil. Effect of supplementation with vitamin A, zinc and zinc and vitamin A.

The interaction of zinc and vitamin A in rats receiving a regional diet of Manaus, supplemented with vitamin A, zinc and zinc and vitamin A was studied. The regional diet was elaborated according to data of Shrimpton and Giugliano (6), for families receiving less than two minimum salaries. The biological test to study the interaction was based on the depletion of zinc and vitamin A in rats in the period of lactation, and a period of repletion where supplements of zinc (0.82 mg%) and vitamin A (94.2 micrograms %) were given, either separately or together, according to the recommendations of the Committee on Laboratory Animal Diets (7). From the results, it was concluded that there was an interaction of these nutrients in terms of mobilization of hepatic vitamin A. Although the regional diet of Manaus did not meet the zinc RDA, the amount present was enough to utilize the available vitamin A. Although the amount of zinc present in the diet, as determined by parameters of bioavilability, such as growth, concentration in organs and zinc-dependent enzymes, was adequately used by the animals, probably due to promoting factors in the diet. The Manaus regional diet needs to be supplemented with vitamin A in order to maintain the hepatic reserves, and with zinc, to maintain the normal levels of vitamin A in plasma.

Animals↗
PubMedDate not supplied

Plasma concentrations of beta-carotene, vitamin A and vitamin E after beta-carotene and vitamin E intake.

We have studied the metabolism (absorption) of beta-carotene and vitamin E by assigning eleven volunteers to receive daily two capsules of OENOBIOL, each containing 15 mg of beta-carotene and 15 mg of vitamin E, over 60 days. The beta-carotene, vitamin E and vitamin A plasma levels were then determined using new methods developed in our laboratory. After two months, the actively treated group's median beta-carotene and vitamin E levels were significantly higher than those of a control group. However, no significant change between treated and control groups in the mean of vitamin A (retinol) plasma levels were observed. Treatment with beta-carotene, a vitamin A precursor, does not significantly modify the vitamin A levels. This conclusion had already been observed and it is assumed that a plasma level of beta-carotene equal or higher than 0.3 mg/L reflects a nutritional intake of provitamins sufficient to support homeostasis of retinol (Brubacher et al., 1982).

Absorption↗
PubMed2005

Plasma concentrations of 25-hydroxy-vitamin D and 1,25-dihydroxy-vitamin D are related to the phenotype of Gc (vitamin D-binding protein): a cross-sectional study on 595 early postmenopausal women.

The major transporter of vitamin D metabolites in the circulation is the multifunctional plasma protein Gc, also known as group-specific component, Gc globulin, vitamin D-binding protein, or DBP. There are several phenotypes of Gc, and we examined the influence of Gc phenotype and Gc concentration on vitamin D status. By using isoelectric focusing we identified the Gc phenotype of 595 caucasian recent postmenopausal women enrolled into the Danish Osteoporosis Prevention Study (DOPS). We measured plasma concentration of Gc by immunonephelometry (coefficient of variation [CV] < 5%), 25-hydroxy vitamin D (25OHD) by a competitive protein-binding assay (CV 10%), and 1,25-dihydroxy-vitamin D (1,25(OH)(2)D) by a radioimmunoassay (CV 6--14%), and calculated index as the molar ratio of vitamin concentration divided by Gc concentration. Plasma levels of Gc, 25OHD, 25OHD index, and 1,25(OH)(2)D, but not 1,25(OH)(2)D index, differed significantly between women with different Gc phenotype, being highest in Gc1-1, intermediate in Gc1-2, and lowest in Gc2-2. In multiple regression analysis, Gc concentration was an independent predictor of 1,25(OH)(2)D, whereas Gc phenotype was a significant predictor of 25OHD concentration, even after adjustment for the effects of season, sunbathing habits, skin thickness, use of vitamin supplements, smoking, and body mass index (BMI). Plasma parathyroid hormone (PTH) level did not differ between Gc phenotypes. Despite the fact that more than 60% of the women with Gc phenotype Gc2-2 had plasma 25OHD levels of less than 50 nmol/L none of them had plasma PTH higher than reference limits. Bone mineral content (BMC), Bone mineral density (BMD), and bone markers did not differ between Gc phenotypes. In conclusion, plasma 1,25(OH)(2)D, 25OHD, and 25OHD index are related to Gc phenotype, and we speculate that the thresholds for vitamin D sufficiency differ between Gc phenotypes.

Cross-Sectional Studies↗
PubMed1979

Response of plasma levels of vitamin A to a dose of vitamin A as an indicator of hepatic vitamin A reserves in rats.

Rats were fed diets deficient [-A] or sufficient [+A] (3 mg retinol equivalents/kg) in vitamin A, and without [-RA] or with [+RA] (12 mg/kg) retinoic acid supplementation for up to 33 days. Rats with plasma vitamin A levels ranging from 7 to 62 micrograms/dl were studied at intervals during progressive depletion of liver stores of vitamin A (expt. 2) and when liver stores were nearly exhausted (less than 10 micrograms/g) or replete (up to 100 micrograms/g) with vitamin A (expt. 1). A dose of retinyl acetate in corn oil (20 micrograms retinol equivalents) was administered by intubation directly into the stomach. The relative dose response (RDR), expressed as a percentage and defined as the absolute magnitude of the rise in plasma vitamin A levels 5 hours after the dose of retinyl acetate, divided by the plasma level of vitamin A attained after 5 hours, was determined for each rat and correlated over a wide range of vitamin A plasma and liver levels. An RDR above 50% invariably was associated with low plasma levels (10 to 30 micrograms/dl) and low liver stores (less than 10 micrograms/g) of vitamin A, whereas an RDR of less than 40% was associated with plasma levels above 30 micrograms/dl and liver stores ranging from 3 to 100 micrograms/g.

Animals↗
PubMed2006

Resistance imparted by vitamin C, vitamin E and vitamin B12 to the acute hepatic glycogen change in rats caused by noise.

The effects of vitamin C, vitamin E and vitamin B12 on the noise-induced acute change in hepatic glycogen content in rats were investigated. The exposure of rats to 95 dB and 110 dB of noise acutely reduced their hepatic glycogens. Vitamin C (ascorbic acid) and vitamin E (alpha-tocopherol) attenuated the noise-induced acute reduction in the hepatic glycogen contents. This result suggests that antioxidants could reduce the change via reactive oxygen species. Vitamin B12 (cobalamin) delayed the noise-induced change, a finding that suggests that vitamin B12 could postpone the acute change via compensating for vitamin B12 deficiency.

Animals↗
PubMed1985

Vitamin B12 absorption in the neonatal piglet. 1. Studies in vivo on the influence of the vitamin B12-binding protein from sows' milk on the absorption of vitamin B12 and related compounds.

The vitamin B12 in sows' milk is strongly attached to a specific 'binder' protein, which is present in excess. The influence of this 'binder' on the uptake and retention of cyanocobalamin and two natural analogues (cobinamide and Co-alpha-[2-methyladenyl]cobamide) was investigated with neonatal piglets. Retention of a single oral dose of cyano[58Co]cobalamin given before 7 d of age was consistently higher with suckled than with early-weaned piglets, as determined by measurement of whole-body radioactivity. Efficiency of retention declined with age, more rapidly in early-weaned than in suckled animals; when the dose was given at 14 d approximately 30% was retained by both groups. Distribution of the retained cyano[58Co]cobalamin within the body of the piglets was the same in both groups; about half was present in the liver. Foraging piglets may ingest adventitious vitamin B12 and its analogues, which are present in the sow's faeces and in contaminated litter. The influence of the vitamin B12-binder in sows' milk on the uptake and retention of two non-cobalamin analogues, and the effects of the analogues on the uptake and retention of vitamin B12 from 2 to 14 d after parturition, were investigated with early-weaned piglets. The analogues were detected in the liver but not in the body organs. They were also present in blood plasma, urine and bile, in high concentration relative to that of vitamin B12. The content of analogues in the liver was very small in relation to the amounts ingested, and much less than that of vitamin B12. There was no indication that the vitamin B12-binder in sows' milk influenced uptake and retention of the analogues, or that ingestion of analogues affected the content of vitamin B12 in the body organs and fluids examined.

Absorption↗
PubMed2005

Influence of vitamin K on anticoagulant therapy depends on vitamin K status and the source and chemical forms of vitamin K.

Warfarin therapy requires close monitoring to avoid excessive bleeding and to maintain the effective therapeutic concentration assessed with the internationalized ratio (INR). High vitamin K intake can decrease the therapeutic effectiveness of warfarin, while poor vitamin K status appears to increase the sensitivity to small changes in vitamin K intake, especially from supplements. Very large amounts of vitamin K from a single meal with vegetables (400 g of vegetables with 700 to 1500 microg of vitamin K1) can measurably change INR, but occasional typical servings (<100 g) would probably have little lasting impact on INR. Warfarin requirements may change in those altering their intake of dark-green vegetables. The 2005 Dietary Guidelines for Americans recommends 3 cups/week of dark-green vegetables, which contain about 100 to 570 microg/serving of vitamin K1. Less well-known sources and chemical forms of vitamin K, such as MK-7 in natto (a fermented Japanese product), also measurably influence INR. Additional research is needed in warfarin-treated patients to fully quantify the interactions among various sources and chemical forms of vitamin K, age, genotype, and other factors.

Anticoagulants↗
PubMed1996

Inhibition of vitamin D receptor-retinoid X receptor-vitamin D response element complex formation by nuclear extracts of vitamin D-resistant New World primate cells.

Most New World primate (NWP) genera evolved to require high circulating levels of steroid hormones and vitamin D. We hypothesized that an intracellular vitamin D binding protein (IDBP), present in both nuclear and cytoplasmic fractions of NWP cells, or another protein(s) may cause or contribute to the steroid hormone-resistant state in NWP by disruption of the receptor dimerization process and/or by interference of receptor complex binding to the consensus response elements present in the enhancer regions of steroid-responsive genes. We employed electromobility shift assay (EMSA) to screen for the presence of proteins capable of binding to the vitamin D response element (VDRE). Nuclear and post-nuclear extracts were prepared from two B-lymphoblastoid cell lines known to be representative of the vitamin D-resistant and wild type phenotypes, respectively. The extracts were compared for their ability to retard the migration of radiolabeled double stranded oligomers representative of the VDREs of the human osteocalcin and the mouse osteopontin gene promoters. A specific, retarded band containing VDR-RXR was identified when wild type cell but not when vitamin D-resistant cell nuclear extract was used in the binding reaction with either probe. In addition, vitamin D-resistant cell nuclear extract contained a protein(s) which was bound specifically to the VDRE and was capable of completely inhibiting VDR-RXR-VDRE complex formation; these effects were not demonstrated with nuclear extract from the wild type cell line or with the post-nuclear extract of the vitamin D-resistant cell line. We conclude that a VDRE-binding protein(s), distinct from IDBP and present in nuclear extract of cells from a prototypical vitamin D-resistant NWP, is capable of inhibiting normal VDR-RXR heterodimer binding to the VDRE.

Animals↗
PubMed1986

Serum vitamin D2 and vitamin D3 metabolite concentrations and absorption of vitamin D2 in elderly subjects.

The serum vitamin D2 and vitamin D3 metabolite concentrations and intestinal absorption of vitamin D2 were determined in healthy ambulatory and chronically institutionalized elderly subjects with normal renal function. The 25-hydroxyvitamin D (25OHD) concentrations were normal in all subjects (range, 8-43 ng/ml), although institutionalized subjects had a significantly lower mean value [19.2 +/- 2 (+/- SEM) ng/ml; P less than 0.01] compared with ambulatory subjects (25.3 +/- 2 ng/ml). All but one ambulatory subject had 25OHD3 as the major circulating form, whereas 25OHD2 was the major circulating metabolite in one third of the institutionalized subjects. The mean 1,25-dihydroxyvitamin D [1,25-(OH)2D] concentration in both groups was normal, but nine subjects had levels at or below the lower limit of normal despite normal 25OHD concentrations. Separate assay of 1,25-(OH)2D2 and 1,25(OH)2D3 revealed proportional distributions similar to those for 25OHD2 and 25OHD3. To study the effect of age on the intestinal absorption of vitamin D, we compared serum vitamin D2 concentrations after oral administration of 50,000 IU vitamin D2 in both healthy vitamin D-sufficient elderly subjects and young adults. We found no evidence of malabsorption of vitamin D in the elderly subjects. In summary, elderly subjects in New York, whether institutionalized or not, have normal serum 25OHD concentrations. However, while most elderly subjects have normal serum 1,25-(OH)2D levels, a significant proportion fail to produce normal concentrations of 1,25-(OH)2D, possibly due to age-related disturbances in renal synthesis of the hormone.

25-Hydroxyvitamin D 2↗
PubMed1994

The relationship between micronuclei in human lymphocytes and plasma levels of vitamin C, vitamin E, vitamin B12 and folic acid.

The cytokinesis-block micronucleus assay is increasingly being applied to the study of spontaneous or induced genetic damage in human lymphocytes, but little is known about dietary and other lifestyle factors that could influence this index. As part of a larger study investigating the role of dietary factors on baseline genetic damage in human lymphocytes from 152 non-smoking females and 113 non-smoking males evenly distributed between the ages of 20 and 87 years, we have measured (a) the micronucleus (MN) frequency and (b) the plasma level of the anti-oxidant vitamins C and E and the B vitamins folic acid and B12. Multiple regression analysis indicated that age (beta value = 0.598, P < 0.0001) was the most important factor influencing the variance of micronucleus frequency in females, while micronutrient levels had no apparent significant effects on genetic damage. In males age was also the predominant factor (beta value = 0.505, P < 0.0001) influencing genetic damage, but vitamin-C level also contributed positively and significantly to the observed MN frequency (beta value = 0.220, P < 0.0228). To avoid the potential confounding effect of collinearity between variables we also performed separate simple regression analysis for each plasma micronutrient in relation to age-adjusted micronucleus frequency; the results from this analysis again showed a significant and positive effect of plasma vitamin C on age-adjusted micronucleus frequency in males only (beta value = 0.188, P = 0.0503), while no effect was observed for the other micronutrients in both sexes. In view of the predominant age effect, we also focused on the data obtained in the youngest age groups of both sexes. In view of the predominant age effect, we also focused on the data obtained in the youngest age groups of both sexes (i.e. 20-30 years olds) and found (a) that the MN frequency in young males is significantly and positively correlated with plasma vitamin C levels (r = 0.823, P < 0.001) but negatively correlated with plasma vitamin B12 status (r = -0.799, P < 0.001) and (b) in females the only significant correlation was an inverse relationship between MN frequency and the combined folate and vitamin B12 plasma levels (r = -0.4632, P < 0.030).(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed2000

Probing the vitamin D sterol-binding pocket of human vitamin D-binding protein with bromoacetate affinity labeling reagents containing the affinity probe at C-3, C-6, C-11, and C-19 positions of parent vitamin D sterols.

The multiple physiological properties of vitamin D-binding protein (DBP) include organ-specific transportation of vitamin D(3) and its metabolites, manifested by its ability to bind vitamin D sterols with high affinity. In the present investigation we probed the vitamin D sterol-binding pocket of human DBP with affinity labeling analogs of 25-hydroxyvitamin D(3) ¿25-OH-D(3) and 1, 25-dihydroxyvitamin D(3) ¿1,25(OH)(2)D(3) containing bromoacetate alkylating probe at C-3 (A-ring), C-6 (triene), C-11 (C-ring), and C-19 (exocyclic methylene) of the parent sterol. Competitive binding assays with DBP showed approximately 22-, 68-, and 2000-fold decrease in the binding of 1,25(OH)(2)-D(3)-11-BE, 25-OH-D(3)-3-BE, and 25-OH-D(3)-6-BE, respectively, compared to that seen with 25-OH-D(3), while there was no significant difference in the DBP-binding affinity of 25-OH-D(3)-19-BE and 25-OH-D(3). Surprisingly, ¿(14)C25-OH-D(3)-11-BE and ¿(14)C1, 25(OH)(2)-D(3)-19-BE failed to label DBP despite high-affinity DBP-binding, indicating the absence of any nucleophilic amino acid in the vicinity of their bromoacetate moiety to form a covalent bond, while these analogs are inside the binding pocket. In contrast, ¿(14)C25-OH-D(3)-6-BE and ¿(14)C25-OH-D(3)-3-BE specifically labeled DBP. BNPS-skatole digestion of DBP labeled with ¿(14)C25-OH-D(3)-3-BE or ¿(14)C25-OH-D(3)-6-BE produced two peptides (M(r) 17,400 and 33,840), with radioactivity associated with the N- and C-terminal peptides, respectively, raising the possibility that either different areas of the same vitamin D sterol-binding pocket, or different domains of DBP might be labeled by these analogs. Successful affinity labeling of recombinant domain I (1-203) of DBP with both reagents indicated that different areas of the same vitamin D-binding pocket (domain I) were labeled. These affinity analogs are potentially useful for "mapping" the vitamin D sterol-binding pocket and developing a functional model.

Acetates↗
PubMed1984

6-Fluoro-vitamin D3: a new antagonist of the biological actions of vitamin D3 and its metabolites which interacts with the intestinal receptor for 1 alpha,25(OH)2-vitamin D3.

The biological activity and the binding affinity for the 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] intestinal receptor of a new fluorine-containing vitamin D compound, namely 6-fluoro-vitamin D3 (6-F-D3), is reported. A significant interaction of 6-F-D3 with the 1,25(OH)2D3 receptor was found, with a relative competitive index (RCI) of 0.26 +/- 0.04, which is intermediate between 25-hydroxyvitamin D3 (0.14 +/- 0.01) and 1 alpha-hydroxyvitamin D3 (0.46 +/- 0.08), where the RCI of 1,25(OH)2D3 is defined to be 100. In contrast, vitamin D3 was unable to interact with the 1,25(OH)2D3 receptor. Also, the biological activity of 6-F-D3 was assessed in vivo in the vitamin D-deficient chick. 6-F-D3 at doses up to 130 nmol displayed no biological action on either intestinal calcium absorption (ICA) or bone calcium mobilization (BCM) over the time interval of 14-48 h after dosing. However, when 130 nmol 6-F-D3 was given 2 h before and 6 h after vitamin D3 (1.62 nmol), a significant inhibition of vitamin D-mediated ICA was noted. Also, a dose of 130 nmol 6-F-D3 given 2 h before and 6 h after 1,25(OH)2D3 (0.26 nmol) significantly inhibited ICA, as measured at 12 h. 6-F-D3 is the first vitamin D analog found which has an ability to both bind to the 1,25(OH)2D3 receptor and to antagonize the production of biological responses by 1,25(OH)2D3.

Animals↗
PubMed1978

[Studies on the vitamin requirement and vitamin supply in fattening turkeys. 2. Checking the vitamin supplements to state-approved mixed animal feed for fattening turkeys].

In turkey fattening experiments, the vitamin A, vitamin D3, vitamin B6, vitamin B12, niacine, pantothenic acid, folic acid, biotine and choline chloride additions to mixed feeds for fattening turkeys were checked. The vitamin A requirement of the fattening turkey is met, in all stages of growth, by adding 3,000 I.U./kg feed. For vitamin D3 the necessary supplements are 1,000 and 500 I.U./kg for starter feed and fattening mixes, respectively. The requirements for vitamins B2, B6, B12, niacine, pantothenic acid, folic acid and biotine of the fattening turkey are covered by the respective amounts contained in the ration components. To ensure adequate choline supply (optimum gain, small losses) during the starter period, the addition of 500 mg/kg feed proved necessary. On the basis of the results presented, recommendations are given for requirement norms and mixed feed supplementation that have been fully implemented in the meantime.

Animal Feed↗
PubMed1978

[Tissue thiamine, riboflavin and vitamin B6 in the aged rat. II. Effects of vitamin supplementation in the diet on the excretion of vitamins and its tissue levels].

Nine and twenty-one months old rats fed a balanced diet were given for 5 weeks an extra supplementation in thiamine, riboflavin and vitamin B6. Control animals were given the same diet but without vitamin extra supplementation. Fecal and urinary vitamin excretions were determined during this 5 weeks period. They were shown to be less important in older rats than in younger ones. Influence of aging and vitamin supplementation on the vitamin contents of organs and tissues were studied on these animals: previous results were confirmed [see LECLERC, Ann. nutrit, Aliment., 1976, 30, 10--25]. From these results and others published elsewhere, it is conclused that in older animals there could be an increased intestinal destruction of the above mentionned vitamin although changes in vitamin metabolism can be involved too.

Aging↗
PubMed2002

Estimated intake and food sources of vitamin A, folate, vitamin C, vitamin E, calcium, iron, and zinc for Guamanian children aged 9 to 12.

This study describes the nutrient intake and food sources of select vitamins and minerals for children on Guam. Food records (n = 954) from public school students aged nine to twelve of all regions on Guam were analyzed for nutrient content and compared to Recommended Dietary Allowances (RDA). Individual foods were condensed into 194 food aggregates and food lists representing 84% to 91% of the major vitamins and minerals in the diet of the children were developed by frequency analysis. Median intake of calcium, vitamin E, folate were less than 50% of the Recommended Dietary Allowance (RDA) and mean intake of these nutrients was 60% RDA or less. Mean and median vitamin A intake was 107% and 76% RDA, respectively. Both mean and median intake of Vitamin C, iron and zinc were present at levels above 100% RDA. Rice, meat, fruit drink from powder, milk, and fortified cereals are foods that provide substantial contributions to the vitamin and mineral content of the diets. Traditional, nutrient dense foods, such as fish, yams, papaya, and mango had minor contributions because of low frequently of consumption. Information from this study can be used to develop specific diet assessment instruments and culturally appropriate nutrition education.

Ascorbic Acid↗