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At least 1,567 records · Page 87Linked to original sources
PubMed2000

Moderately low vitamin B12 does not compromise transmethylation in adults on a free diet: implications for assessment of vitamin B12 status.

Lower reference limits for vitamin B12 are often defined solely in relation to haematological criteria. This may be misleading and there is evidence indicating that biochemical anomalies should also be considered. In 50 patients we measured creatine, as the major product of B12-mediated remethylation, to see if this helps the definition of the B12 reference interval and to investigate the possible effect of low B12 on essential transmethylation. Vitamin B12 values were grouped into six fractiles covering the range 50-500 ng/L; the corresponding creatine results were assessed by analysis of variance giving F = 0.94 and a significance of 0.466. Although no correlation between B12 and creatine was found, and therefore no obvious effect on transmethylation of low B12 concentration, this must be interpreted with respect to methionine availability. Other factors indicate that biochemical perturbations should be taken into account when defining vitamin B12 reference intervals.

Analysis of Variance↗
PubMed2002

Vitamin B12 deficiency, tumor necrosis factor-alpha, and epidermal growth factor: a novel function for vitamin B12?

Vitamin B12 deficiency was recently shown to be associated with elevated levels of tumor necrosis factor-alpha and decreased levels of epidermal growth factor in both rats and humans. These findings suggest a novel pathogenetic mechanism underlying the neuropathology of vitamin B12 deficiency. They may also explain putative relationships between vitamin B12 deficiency and certain disorders, including Alzheimer's disease, rheumatoid arthritis, and AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Triglyceride-lowering effect of dietary vitamin E in streptozocin-induced diabetic rats. Increased lipoprotein lipase activity in livers of diabetic rats fed high dietary vitamin E.

High vitamin E supplementation in the diets of streptozocin-induced diabetic rats eliminates accumulation of lipid peroxides in the plasma and the liver, returns the plasma triglycerides toward normal levels, and increases the activity of lipoprotein lipase. Vitamin E has no effect on the levels of insulin or glucose. These findings suggest that vitamin E increases the total hepatic triglyceride lipase activity by increasing the lipoprotein lipase activity possibly by protecting the membrane-bound lipase against peroxidative damage.

Animals↗
PubMedDate not supplied

Megaloblastic anaemia: response to Amples A and B (folic acid, vitamin B12 (Cyanocobalamin), niacin and vitamin C)--a case report.

BACKGROUND: Megaloblastic anaemia is prevalent in our society and patients are diagnosed late. METHOD: Case Report of a patient with megaloblastic anaemia and discussion of relevant literature. RESULTS: A 50 year old Nigerian trader with recurrent chronic anaemia and repeated blood transfusions (Eight units in 10 days) was finally diagnosed to have megaloblastic anaemia. He was commenced on intramuscular, Ample A and Ample B (folic acid 0.7mg, vitamin B12 (Cyanocobalamin) 2500g, niacin 12mg and vitamin C 150mg) on alternate days (6 doses) then weekly as maintenance until haematocrit returned to normal. Response was dramatic; haemoglobin was 6.4g/dl before, 7.9g/dl after the second dose and 11.5g/dl after the 6th dose of the drug. The corrected retic was 2.0% before, 4.6% 72hrs after and 8.4% after the 6th dose. The MCV decreased from 105fl before to 79fl after the 6th dose of the drug. His packed cell volume has remained above 35% after completing the 6th dose and during maintenance therapy. CONCLUSION: The combination of Cyanocobalamin, folic acid, niacin, and vitamin C, in Amples A and B is complementary. Treatment with Amples A and B is effective and affordable in the management of megaloblastic anaemia.

Anemia, Megaloblastic↗
PubMedDate not supplied

[Chromatographic analysis of water-soluble vitamins. I- Chromatographic behaviour of water-soluble vitamins on Aminex resins (author's transl)].

The most important water-soluble vitamins are quantitatively determined by high pressure chromatography using porous ion exchange resins. Thiamine and Riboflavine are separated by a cation exchange resin Aminex A5 using 0.3 M KCI in 0.1 M potassium phosphate pH 8.0 buffer as mobile phase; pyridoxamine, pyridoxol, pirydoxal and nicotinamide are successfully chromatographated on the same type of cationic resin using a linear gradient both of pH and ionic strength as mobile phase. Anionic vitamins like L-Ascorbic Acid and Nicotinic Acid are separated on Aminex A14 at acidic values of pH, using isocratic conditions of the ionic modifier. Under the described experimental conditions, the reproducibility of VR, RS and peak area are of 2.5% and 3% respectively. The sensitivity relative to the vitamins tested ranges from 100 to 250 ng.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

The effect of cigarette smoking on vitamin C and vitamin E levels of gingival crevicular fluid.

The purpose of this study was to assay the ascorbic acid and tocopherol levels in gingival crevicular fluid (GCF) of smokers and nonsmokers with clinically healthy gingiva. The comparison was determined between the area physically exposed to smoke and the controlateral area. All tested areas required to be free from periodontal diseases at a screening examination. 41 students (16 nonsmokers and 25 smokers) were enrolled in this study. GCF samples were collected in two regions: area of habitual cigarette placement and controlateral area. Areas sampled were at midbuccal and midlingual sites of all teeth 3, 5, 6, and 7. Ascorbic acid and tocopherol values of GCF were determined by HPLC. Smokers were found to have significant (p < 0.05) lower levels of vitamin C in comparison to nonsmokers in all regions tested. Mean GCF tocopherol concentration of smokers did not reveal significant differences between the two regions examined. The vitamin A levels revealed an unsignificant low value in smokers in comparison to control subjects. Tobacco smoke can be the cause of a gingival damage by decrease of vitamin C and A operating through a vasoconstriction and a reduction of the antioxidant properties.

Adult↗
PubMedDate not supplied

[Vitamin "A" and biological membranes. Nota V - Fatty acid composition of erythrocyte stroma in vitamin A deficient rats (author's transl)].

Two groups of albino male rats, were fed for 90 days with a balanced and vitamin A-free diet rispectively, to observed changes, if any, in the fatty acid composition of erythrocyte membranes. The blood was separated with heparin, total lipids from erythocyte stroma were extracted and fatty acids analyzed by gaschromatography. It was noticed an increase in saturated fatty acids; at the same time mono- and, above all, polyunsaturated fatty acids decreased; the results agree with those obtained in rats fed for 30 and 60 days with Vitamin A-free diet as similar changes were observed in liver mitochondrial membranes of the rats, under study, we presume vitamin A modifies, to some extent, the biosyntesis of unsaturated fatty acids.

Animals↗
PubMed1975

[Effect of tannic acid on liver levels of vitamin A in rats maintained on balanced diets or deprived of this vitamin].

A 6 month study in rats fed a balanced diet containing 3,2 p. 100 tannic acid resulted in a marked decrease of the hepatic concentration of vitamin A. In an other study, rats were fed vitamin A deficient diets containing 0, 0,8, 1,6 and 3,2 p. 100 tannic acid. There was no effect of tannic acid on the hepatic concentrations of vitamin A determined on days 20, 40 and 60.

Animals↗
PubMed2004

Circulating vitamin D metabolites, polymorphism in vitamin D receptor, and colorectal adenoma risk.

OBJECTIVE: Vitamin D is a potential agent for the prevention of colorectal cancer possibly through mechanisms mediated by the vitamin D receptor (VDR). We investigated the association of circulating vitamin D metabolites and a genetic variant of the VDR gene with advanced colorectal adenoma, a precursor lesion of colorectal cancer. METHODS: Cases with advanced adenoma of the distal large bowel and gender- and ethnicity-matched controls with a negative sigmoidoscopy were randomly selected from participants in the Prostate, Lung, Colorectal and Ovarian Cancer Screening trial. Genotype analysis of the VDR TaqI polymorphism was completed on 763 cases and 774 controls. Serum levels of 25-hydroxyvitamin D [25(OH)D] and 1,25-dihydroxyvitamin D [1,25(OH)(2)D] were measured in a subset of 394 cases and 397 controls. RESULTS: Serum levels of 25(OH)D were inversely associated with advanced adenoma risk in women but not in men. Comparing those in the highest quintile with those in the lowest quintile, the risk for advanced adenoma decreased by 73% in women [odds ratio (OR) = 0.27, 95% confidence interval (95% CI) = 0.11-0.69; P for trend = 0.0002], while the risk did not decrease in men (OR = 1.10, 95% CI = 0.60-2.05; P for trend = 0.85). In women, 25(OH)D levels were significantly higher in current users of hormone replacement therapy (HRT) than in former or never HRT users. Neither serum 1,25(OH)(2)D nor VDR TaqI genotype was associated with advanced adenoma risk. CONCLUSION: Higher serum 25(OH)D levels were associated with decreased adenoma risk. Serum 1,25(OH)(2)D and VDR TaqI genotype were not associated with adenoma risk.

Adenoma↗
PubMed1992

Synthesis of fluoro- and hydroxy-derivatives of vitamin K as substrates or inhibitors of the liver microsomal vitamin K-dependent carboxylase.

The rat liver microsomal vitamin K-dependent carboxylase catalyzes the carboxylation of glutamyl to gamma-carboxyglutamyl residues in the presence of reduced vitamin K, O2 and CO2. The specificity of the enzyme for the vitamin substrate has been probed by the synthesis of a series of fluoro- hydroxy- and methoxy-analogs. 2-Fluoro-methyl-3-phytyl-1,4-naphthoquinone and 2-methyl-3-(1'-fluorodecyl)-1,4-naphthoquinone were synthesized but found to be unstable under enzyme assay conditions. The reduced (naphthohydroquinone) forms of 2-hydroxy-methyl-3-phytyl-1,4-naphthoquinone, 2-methoxymethyl-3-phytyl-1,4-naphthoquinone and 2-methyl-3-(1'-hydroxy-decyl)-1,4-naphthoquinone were inactive as substrates, but inhibitors of the enzyme. The two hydroxy analogs were shown to be low Ki (less than 10 microM) inhibitors of the reduced 2-methyl-3-phytyl-1,4-naphthoquinone-dependent activity of the enzyme. The oxidized forms of these compounds did not inhibit the enzyme and they had no activity as in vivo anticoagulants.

Animals↗
PubMed2005

[Association of vitamin D receptor gene Apa I polymorphism with vitamin D deficiency rickets].

OBJECTIVE: To study the association between vitamin D receptor (VDR) gene Apa I polymorphism and vitamin D deficiency rickets in children of Shanxi Han ethnic group, and to explore the significance of individual hereditary factors in the development of rickets. METHODS: This was a case control study. The grouping criteria were serum 25(OH)D(3) level, blood bone alkaline phosphatase and clinical symptom, respectively. The laboratory test methods were enzyme linked immunoassay and radioimmunoassay. PCR-RFLP technology was applied to examine VDR gene Apa I site polymorphism and Hardy-Weinberg hereditary balance test was used to examine the coincidence of gene distribution. RESULTS: Frequencies of AA, Aa and aa genotypes were 5.0%, 52.5% and 42.5% in the rickets group and 4.4%, 55.9% and 39.7% in the control group, respectively. Frequencies of A and a genotypes were 31.3% and 68.7% in the rickets group and 32.3% and 67.7% in the control group, respectively. There was not significant difference in the frequency distribution of VDR genotype and allelic genes between two groups (chi(2) = 0.089, P > 0.05; chi(2) = 0.028, P > 0.05). There was significant difference in the serum 25(OH)D(3) between two groups (t = -8.919, P < 0.01). CONCLUSION: The distribution of VDR gene Apa I polymorphism in children of Han ethnic group is balanced relatively. The Frequency of a allelic genes is 67.7% which is therefore the superior gene. VDR gene polymorphism might not be important in an individual's susceptibility to development of vitamin D deficiency.

Calcifediol↗
PubMed2006

[Status of vitamin A, vitamin B2, iron and an-oxidantive activity in anemic pregnant women in China].

OBJECTIVE: To investigate the status of vitamin A(VA), vitamin B2 (VB2), iron and anoxidative function in anemic and non-anemic pregnant women. METHODS: 426 anemic and 36 non-anemic pregnant women were included in the study. The survey of 24-hour's diet recall of pregnant women was made to evaluate intake of iron, VB2, folic acid, etc by the nutrition software provided by Beijing 301 hospital, iron and VA were measured by Radioimmunoassay (RIA) and by high-pressure liquid chromatography. VB2 status was detected using the assay for erythrocyte glutathione reductase (Egr; EC 1.6.4.2) activity. SOD and GSH-Px activities and MDA were determined using commercial kits. Peripheral blood erythrocyte membrane fluidity was detected by using 1,6-diphenyl-1,3,5-hexatriene as a probe, the degree of fluorescence polarization (P) at 25 degrees C of disrupted cells plasma membranes were compared for a variety of systems. RESULTS: Median intakes of protein and vitamin C met the current Chinese RNIs for pregnancy, whereas intakes of(VA) and VB2 were well below the recommendations. Intake of iron were above 90%, but the main sources of iron are vegetables. Plasma VA (1.25 micromol/L) and iron (20.57 microg/L) were lower, BGRAC (1.79) was higher than that in non-anemia group (VA 1.57 micromol/L, SF 33.16 microg/L, BGRAC 1.52). The level of plasma SOD (77.1U/ml) and the activity of GSH-Px (61.9U) were lower than those in non-anemia group (92.2U/ml, 71.6U, P < 0.05), while MDA (4.58 nmol/ml) level and erythrocyte membrane (P = 0.2622, eta = 2.7465) fluidity were higher than those non-anemia group(MDA = 3.78 nmol/ ml, P = 0.2360, eta = 2.3658). CONCLUSION: Plasam VA, VB2 and iron, antioxidantcapacity and erythrocyte membrane fluidity were decreased in the anemic pregnant women.

Adult↗
PubMed1988

Vitamin K-dependent carboxylase. Stoichiometry of vitamin K epoxide formation, gamma-carboxyglutamyl formation, and gamma-glutamyl-3H cleavage.

The rat liver microsomal vitamin K-dependent carboxylase catalyzes the carboxylation of peptide-bound glutamyl residues to gamma-carboxyglutamyl (Gla) residues with the concomitant formation of vitamin K 2,3-epoxide (KO). These studies have demonstrated that the half-reaction, formation of KO, occurs in the absence of carboxylation at low glutamyl substrate concentration but that the ratio of KO/Gla approaches unity as the glutamyl substrate concentration is increased. Utilization of the carboxylase substrate Phe-Leu-[gamma-3H] Glu-Glu-Leu has demonstrated that the ratios of KO/gamma-C-H bonds cleaved and Gla/gamma-C-H bonds cleaved are equivalent at high substrate concentrations and that these ratios approach unity. At low substrate concentrations, KO formation occurs at a higher rate than gamma-H bond cleavage. These data are consistent with a mechanism involving the formation of an oxygenated intermediate from vitamin KH2 and O2 that is converted to KO during hydrogen abstraction from the gamma-position of the Glu substrate. In the absence of a Glu substrate, the intermediate is converted to KO by a mechanism not coupled to glutamyl activation.

1-Carboxyglutamic Acid↗
PubMed1979

Vitamin D intoxication and the pathogenesis of vitamin D nephropathy in the dog.

Dogs given excess vitamin D (500 or 1,000 micrograms/kg of body weight each day for 1 to 3 weeks were observed for clinical and pathologic changes of increased blood pressure and of characteristic nephropathy associated with vitamin D toxicosis or hypercalcemia. Serum calcium and serum urea nitrogen (UN) increased throughout the treatment period, but serum phosphorus remained within the normal range. Plasma renin activity increased markedly. Blood pressure showed only insignificnat changes (P = greater than 0.05). Gross and microscopic examination of the kidneys suggested vascular-oriented changes with an ischemic basis. Glomerular vascular poles showed hypertrophy and hyperplasia of juxtaglomerular cells. Ultrastructually, an increase in the number of secretory granules was noticed in these cells. A hypothesis regarding the mechanism of renal injury during vitamin D toxicosis is presented.

Animals↗
PubMed1975

Vitamin K and the biosynthesis of prothrombin. V. Gamma-carboxyglutamic acids, the vitamin K-dependent structures in prothrombin.

Tryptic peptides obtained from normal prothrombin have been compared with those obtained from prothrombin synthesized by cattle given the vitamin K antagonist dicumarol. Two peptides were found which contain vitamin K-dependent structures. These peptides contain residues 4 through 10 and residues 12 through 44, respectively. One of these (residues 4 through 10) has previously been shown to contain gamma-carboxyglutamic acid residues. Digestion of this peptide with aminopeptidase M and carboxypeptidase B yielded a tetrapeptide (residues 6 through 9). Mass spectra of this peptide showed that it has the structure Leu-Glu(CO2)-Glu(CO2)-Val. The structure of the peptide containing residues 12 through 44 was determined by automated degradation in a peptide sequenator. The modified glutamic acid residues were identified by mass spectrometric comparison with the thiohydantoin derivatives of synthetic gamma-carboxyglutamic acid. This approach unequivocally demonstrated that all of the first 10 glutamic acid residues in prothrombin are carboxylated to form gamma-carboxyglutamic acid residues. Evidence is also presented that indicates that these gamma-carboxyglutamic acid residues constitute the entire vitamin K-dependent modification of prothrombin.

Amino Acid Sequence↗
PubMed1979

Analysis of fat-soluble vitamins. XXII. High performance liquid chromatographic determination of vitamin D in concentrates. Collaborative study.

A collaborative study was carried out which compared the official chemical method (43.B14-43.B24), the HPLC method according to Hofsass et al. including maleic anhydride treatment, and the HLPC procedure according to De Vries et al. for vitamin D concentrates. A total of 396 samples were distributed to 33 collaborators for analysis. Five laboratories performed both the chemical and the HPLC methods. Five laboratories performed the Hofsass method and 16 laboratories performed the De Vries method. The results for the chemical method agreed with the theoretical values for the samples, and the standard deviation was comparable to that obtained in previous AOAC collaborative studies. Collaborative results for the Hofsass method were low. In addition, incorrect use of a fixed conversion factor (1/0.586) and necessity of a double chromatogrpahic system on a non-treated and a treated vitamin D sample reduce the effectiveness of the method. There were no adverse reactions to the DE Vries HPLC method. It is recommended that the method be adopted official first action as an alternative procedure for determining vitamin D in concentrates, excluding powders containing irradiated 7-dehydrocholesterol.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

[E-vitamin activity of vitamin E derivatives with experimental encephalomalacia in chicks].

When adding pharmacopoeian alpha-tocopherylacetate, short-chain alpha-tocopherylacetate, alpha-tocopherylquinine, short-chain alpha-tocopherylquinone and alpha-tocopheronolactone to E-avitaminotic rations pharmacopoeian alpha-tocopherylacetate and alpha-tocopheronolactone manifest the highest E-vitamin activity in preventing encephalomalacia in chickens. The action of alpha-tocopheronolactone is not directly associated with changes in the content of vitamin E and ubiquinone in the brain and liver tissues. All the studied derivatives are effective in increasing resistance of erythrocytes to osmotic hemolysis. The data obtained evidence for a nonspecific function of vitamin E in preventing alimentary encephalomalacia in chickens as well as for the absence of disturbances in ubiquinone metabolism under conditions of the E-hypovitaminosis experimental model.

Animals↗
PubMed1983

Vitamin K-dependent carboxylase. Demonstration of a vitamin K- and O2-dependent exchange of 3H from 3H2O into glutamic acid residues.

The rat liver vitamin K-dependent carboxylase has been studied with t-butoxycarbonyl-Glu-Glu-Leu-OMe as a substrate. The crude enzyme preparation catalyzes incorporation of 3H from media 3H2O into the glutamic acid residues of the substrate. This incorporation is dependent on vitamin KH2 and O2, is stimulated by NaCN, and is inhibited by increasing the HCO3- concentration. These data lend support to an enzymatic mechanism involving a vitamin K- and O2-dependent formation of a carbanion at the gamma-position of the glutamic acid residue followed by attack of CO2 to form gamma-carboxyglutamic acid.

Aerobiosis↗