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At least 451 records · Page 25Linked to original sources
PubMed2000

Determination of eight water- and fat-soluble vitamins in multi-vitamin pharmaceutical formulations by high-performance liquid chromatography.

In the present work, a reversed-phase high-performance liquid chromatographic procedure has been developed for the determination of water-soluble vitamins (thiamine hydrochloride, pyridoxine hydrochloride, nicotinamide, riboflavin phosphoric ester and cyanocobalamine) and fat-soluble vitamins (retinol palmitate, cholecalciferol, alpha-tocopherol acetate) in multi-vitamin pharmaceutical formulations. The sample treatment proposed consists of a solid-phase extraction with C18 AR cartridges that allow the separation of fat-soluble vitamins, which were retained on the sorbent, from water-soluble vitamins. Afterwards, the water-soluble vitamins were analysed by HPLC on a Nova-Pack C18 (150x3.9 mm, 4 microm) analytical column, using CH3OH-0.05 M CH3COONH4 as mobile phase. The chromatographic analysis of the fat-soluble vitamins was carried out after their sequential elution with methanol and chloroform from C18 sorbent, on the above column. The mobile phase employed was MeOH-CH2CN (95:5, v/v) working at a flow-rate of 2 ml min(-1) in isocratic mode. The solid-phase extraction for these vitamins had been previously optimised. The experimental variables studied were: application volume, elution solvents and cleaning solutions. The UV-Vis detection of vitamins was made at 270 nm for all the water-soluble vitamins (362 nm for B12) and 285 nm for the water-soluble and fat-soluble vitamins present in real samples at different concentration levels. The accuracy of the method was tested obtaining an average recovery ranging between 78 and 116%.

Chromatography, High Pressure Liquid↗
PubMed2002

Photoprotective potential of lycopene, beta-carotene, vitamin E, vitamin C and carnosic acid in UVA-irradiated human skin fibroblasts.

The photoprotective potential of the dietary antioxidants vitamin C, vitamin E, lycopene, beta-carotene, and the rosemary polyphenol, carnosic acid, was tested in human dermal fibroblasts exposed to ultraviolet-A (UVA) light. The carotenoids were prepared in special nanoparticle formulations together with vitamin C and/or vitamin E. Nanoparticle formulations, in contrast to dimethylsulphoxide, stablized lycopene in the cell culture medium and allowed efficient cellular uptake. The presence of vitamin E in the formulation further increased the stability and cellular uptake of lycopene. UVA irradiation of the human skin fibroblasts led to a 10-15-fold rise in metalloproteinase 1 (MMP-1) mRNA. This rise was suppressed in the presence of low microM concentrations of vitamin E, vitamin C, or carnosic acid but not with beta-carotene or lycopene. Indeed, in the presence of 0.5-1.0 microM beta-carotene or lycopene, the UVA-induced MMP-1 mRNA was further increased by 1.5-2-fold. This increase was totally suppressed when vitamin E was included in the nanoparticle formulation. Heme-oxygenase 1 (HO-1) mRNA expression was strongly induced by UVA irradiation but none of the antioxidants inhibited this effect at the concentrations used in this study. Indeed, beta-carotene or lycopene (0.5-1.0 microM) led to a further 1.5-fold rise in the UVA-induced HO-1 mRNA levels. In conclusion, vitamin C, vitamin E, and carnosic acid showed photoprotective potential. Lycopene and beta-carotene did not protect on their own but in the presence of vitamin E, their stability in culture was improved and the rise in MMP-1 mRNA expression was suppressed, suggesting a requirement for antioxidant protection of the carotenoids against formation of oxidative derivatives that can influence the cellular and molecular responses.

Abietanes↗
PubMed2000

Vitamin supplements and cardiovascular risk: review of the randomized trials of homocysteine-lowering vitamin supplements.

Epidemiological studies have shown that higher blood homocysteine levels appear to be associated with higher risks of coronary, cerebral, and peripheral vascular disease and are inversely related to blood levels of folate and of vitamin B12 and vitamin B6. However, observational studies cannot exclude the possibility that elevated homocysteine levels may be associated with some other factor, rather than being causally related to vascular disease. Large-scale clinical trials of sufficient dose and duration of treatment are required to test this hypothesis, but there was substantial uncertainty about the optimal vitamin regimen to test in such trials. A meta-analysis of 12 randomized trials of vitamin supplements to lower homocysteine levels was carried out to determine the optimal dose of folic acid required to lower homocysteine levels and to assess whether vitamin B12 or vitamin B6 had additive effects. This meta-analysis demonstrated that reductions in blood homocysteine levels were greater at higher pretreatment blood homocysteine levels and at lower pretreatment folate concentrations. After standardization for a pretreatment homocysteine concentration of 12 micromol/L and folate concentration of 12 nmol/L (approximate average concentrations for western populations), dietary folic acid reduced homocysteine levels by 25% (95% confidence interval [CI]: 23 to 28%) with similar effects in a daily dosage range of 0.5 to 5 mg. Vitamin B12 (mean 0.5 mg) produced an additional reduction in blood homocysteine of 7%, whereas vitamin B6 (mean 16.5 mg) did not have any significant effect. Hence, in typical populations, daily supplementation with both 0.5 to 5 mg folic acid and about 0.5 mg vitamin B12 would be expected to reduce homocysteine levels by one quarter to one third (from about 12 micromol/L to about 8 to 9 micromol/L). Large-scale randomized trials of such regimens are now required to determine whether lowering homocysteine levels by folic acid and vitamin B12, with or without added vitamin B6, reduces the risk of vascular disease.

Adult↗
PubMed2000

Efficacy of a vitamin A-fortified wheat-flour bun on the vitamin A status of Filipino schoolchildren.

BACKGROUND: Wheat flour is a possible food vehicle for vitamin A fortification. OBJECTIVE: This study assessed the efficacy of consumption of a vitamin A-fortified wheat-flour bun (pandesal) on the vitamin A status of school-age children. DESIGN: This was a double-masked clinical trial conducted in 396 and 439 children aged 6-13 y attending 4 rural schools in the Philippines. The children were randomly assigned to a vitamin A-fortified (experimental) or nonfortified (control) group. A 60-g vitamin A-fortified pandesal (containing approximately 133 microg retinol equivalents) or a nonfortified pandesal was consumed by the children 5 d/wk for 30 wk. Vitamin A status, hemoglobin concentration, anthropometric status, morbidity, and dietary intake were assessed at baseline and 30 wk later. A modified relative dose response (MRDR) was assessed in a subsample of 20% of the children ( approximately 75/group) with the lowest initial serum retinol concentration at the 30-wk follow-up. RESULTS: Baseline serum retinol significantly modified the effect of the intervention. The fortified group, whose initial serum retinol concentrations were below the median, had a 0.07 +/- 0.03-micromol/L greater improvement in serum retinol at the 30-wk follow-up than did the control group (P: = 0.02). Improved vitamin A status was also evident in the MRDR subsample. End-of-study differences in the MRDR showed that vitamin A- fortified pandesal intake decreased the percentage of children with inadequate liver vitamin A stores by 50% (15.3% compared with 28.6%; P: = 0.05). CONCLUSIONS: Daily consumption of vitamin A-fortified pandesal significantly improved the vitamin A status of Filipino school-age children with marginal-to-low initial serum retinol concentrations.

Adolescent↗
PubMed1997

Effect of vitamin K1 supplementation on vitamin K status in cystic fibrosis patients.

BACKGROUND: Patients with cystic fibrosis are at risk for impaired vitamin K status due to fat malabsorption from pancreatic insufficiency. This study was designed to assess vitamin K status and measure the effect of vitamin K1 supplementation in cystic fibrosis patients. METHODS: Eighteen outpatients participated in a crossover study to determine the effect of vitamin K1 (phylloquinone) supplementation. After obtaining initial data, each subject was randomly assigned to either a 4-week study treatment of 5 mg oral vitamin K1 supplementation per week, or no supplementation and then crossed over to the other treatment for a second 4 week period. Plasma, serum and urine samples were collected and analyzed pre-study and at the end of each study period. RESULTS: The mean concentration of plasma vitamin K1 for the supplemented group was significantly higher than the unsupplemented group, [0.34 nmol/L and 0.21 nmol/L, respectively (p < 0.05)]. The percent of undercarboxylated osteocalcin increased on supplementation from 17% to 31%, (p < 0.005). Prothrombin induced in vitamin K absence (PIVKA-II) increased on supplementation from 5 ng/mL to 22 ng/mL, (p < 0.005). The ratio of urinary gamma-carboxyglutamic acid/creatinine was similar for both study periods. CONCLUSIONS: In contrast to other studies in cystic fibrosis, this study demonstrated a need for vitamin K1 supplementation. The carboxylation state of osteocalcin and PIVKA-II were the most sensitive indices of changes in vitamin K1 status. Although the 5 mg vitamin K1/week dose improved these vitamin K parameters, normal levels were not achieved.

1-Carboxyglutamic Acid↗
PubMed1991

Pharmacokinetics of vitamin K in mothers and children in the perinatal period: transplacental transport of vitamin K2 (MK-4).

In order to examine the pharmacokinetics of vitamin K2, vitamin K2 (MK-4) was intravenously injected into mothers, and its transfer to placental tissue and the fetuses was examined. While incorporation of vitamin K2 into placental tissue was relatively active, transfer of vitamin K2 to fetal blood (cord blood) was small. So it was indicated that vitamin K2 incorporated into placental tissue from maternal blood is initially stored in the placenta and then gradually released into the fetal blood. Since vitamin K deficiency has been pointed out, release of vitamin K2 into milk was also examined. When vitamin K2 (MK-4) was injected into mothers, the release of vitamin K2 into milk increased with time even after the plasma vitamin K2 concentration in maternal blood decreased. So the presence of a vitamin K2 concentrating mechanism in the mammary tissue was indicated.

Animals↗
PubMed1988

Discrepancies between serum and erythrocyte concentrations of vitamin E in hemodialysis patients: role of HDL-bound fraction of vitamin E.

Recently, we have demonstrated that hemodialysis (HD) patients have higher serum and lower erythrocyte concentrations of vitamin E than controls. It is known that transfer of vitamin E from serum to erythrocyte is mostly due to high-density lipoproteins (HDL). For a better definition of the pattern of distribution of vitamin E in HD patients, we have dosed the amount of vitamin bound to serum HDL fraction. In 8 patients and in 8 healthy controls, we have determined the concentration of serum erythrocyte and HDL-bound vitamin E. The latest was obtained on an ultracentrifuged HDL fraction. HDL fractions from HD patients have been found to contain larger amounts of vitamin E than controls. The previously described higher serum and lower erythrocyte concentrations of vitamin E in HD patients have been confirmed in the study. The deficit of vitamin E in the membranes of erythrocytes from HD patients has been shown to be the result of increased consumption of the vitamin in the erythrocyte membranes, where it represents the major antioxidant agent. However, the finding of increased amounts of vitamin bound to HDL in HD patients suggests that the transfer of the vitamin to the erythrocyte membranes may also be defective.

Adult↗
PubMed1993

Exogenous calciferol (vitamin D) and vitamin D endocrine status among elderly nursing home residents in the New York City area.

OBJECTIVE: To determine the role and relative importance of sources of exogenous calciferol (vitamin D) in maintaining vitamin D endocrine status in the mid-winter and early spring in a representative sample of institutionalized elderly persons in the New York City area. DESIGN: Cross-sectional survey. SETTING: A privately-run urban nursing home and the long-term care unit of a suburban public hospital. PARTICIPANTS: Residents aged 60 years and older scheduled for a routine annual physical examination and an additional group of individuals ascertained by random sampling. Those with a history of anti-convulsant or glucocorticoid use, liver disease, chronic renal disease (or serum creatinine > 1.5 mg/dL), parathyroid disease, Paget's disease, gastric surgery, or pharmacological vitamin D use were excluded. Of 301 sampled individuals, 221 were found eligible to participate, and 109 were successfully enrolled. RESULTS: The average vitamin D intake was 379 IU/day (range 55-1006 IU/day) and total vitamin D intake was below the Recommended Dietary Allowance in 16% of subjects. Fifty percent of total vitamin D intake came from fortified milk, and 26% came from vitamin supplements. Vitamin supplement use was not associated with low dietary intake. Among subjects taking a supplement containing 400 IU/day, none had serum calcidiol levels below 15 ng/mL, while among subjects with vitamin D intake between 200 and 400 IU/day, 46% had serum calcidiol levels below 15 ng/mL and 14% had calcidiol levels below 10 ng/mL. Vitamin D intake from non-supplement sources (but not from supplements) appeared to have a negative association with serum calcitriol levels. CONCLUSIONS: Many nursing home residents may require vitamin supplements in order to achieve optimal levels of calciferol replacement. The choice of a vehicle for calciferol replacement may affect calcitriol levels.

Aged↗
PubMed2004

The physiology of vitamin K nutriture and vitamin K-dependent protein function in atherosclerosis.

Recent advances in the discovery of new functions for vitamin K-dependent (VKD) proteins and in defining vitamin K nutriture have led to a substantial revision in our understanding of vitamin K physiology. The only unequivocal function for vitamin K is as a cofactor for the carboxylation of VKD proteins which renders them active. While vitamin K was originally associated only with hepatic VKD proteins that participate in hemostasis, VKD proteins are now known to be present in virtually every tissue and to be important to bone mineralization, arterial calcification, apoptosis, phagocytosis, growth control, chemotaxis, and signal transduction. The development of improved methods for analyzing vitamin K has shed considerable insight into the relative importance of different vitamin K forms in the diet and their contribution to hepatic vs. non-hepatic tissue. New assays that measure the extent of carboxylation in VKD proteins have revealed that while the current recommended daily allowance for vitamin K is sufficient for maintaining functional hemostasis, the undercarboxylation of at least one non-hemostatic protein is frequently observed in the general population. The advances in defining VKD protein function and vitamin K nutriture are described, as is the potential impact of VKD proteins on atherosclerosis. Many of the VKD proteins contribute to atherogenesis. Recent studies suggest involvement in arterial calcification, which may be influenced by dietary levels of vitamin K and by anticoagulant drugs such as warfarin that antagonize vitamin K action.

Animals↗
PubMed1993

Partners in defense, vitamin E and vitamin C.

In addition to the enzymic mechanism of free-radical removal, essential nutrients that can scavenge free radicals, such as vitamins E and C, constitute a strong line of defense in retarding free radical induced cellular damage. Distinct pathways for the repair of oxidized vitamin E in human cells have been recently identified. Within 0.5 min after the addition of arachidonic acid to a human platelet homogenate, over half of the platelet vitamin E and added arachidonate were metabolized by platelet cyclooxygenase and lipoxygenase pathways. After adding nordihydroguaiaretic acid, a lipoxygenase inhibitor and a strong reductant, over 60% of the oxidized vitamin E was regenerated. To test other physiological, water-soluble reductants that may help regenerate vitamin E, eicosatetraynoic acid, a lipoxygenase inhibitor that is not an antioxidant, was used. In this system, both ascorbate and glutathione provided significant vitamin E regeneration. Kinetic analysis and studies of vitamin E regeneration in a protein-denaturing system revealed that ascorbate regenerates vitamin E by a nonenzymic mechanism, whereas glutathione regenerates vitamin E enzymatically. These studies suggest that significant interaction occurs between water- and lipid-soluble molecules at the membrane-cytosol interface and that vitamin C may function in vivo to repair the membrane-bound oxidized vitamin E.

Animals↗
PubMed1990

Bone disease in chronic childhood cholestasis. II. Better absorption of 25-OH vitamin D than vitamin D in extrahepatic biliary atresia.

Infants with extrahepatic biliary atresia (EHBA) commonly develop rickets in infancy, whereas long-term survivors with EHBA commonly develop osteopenia with increasing age. We evaluated baseline vitamin D (D2 and D3), 25-OH vitamin D2 and D3, 1,25(OH)2 vitamin D, bone mineral content, and vitamin D2 and 25-OH vitamin D3 absorption in six infants and children (age 4-22 mo) with EHBA whose portoenterostomy failed to produce bile flow (group 1) and five infants and children (age 10/12 to 8-4/12 y) with EHBA whose portoenterostomy repair led to good postoperative bile flow (group 2). Baseline serum vitamin D2 and D3 were undetectable in all subjects in group 1 despite supplements of 2500-5000 IU/day, whereas all group 2 subjects given supplements (doses 400-5000 IU/d) had measurable levels. Baseline serum 25-OH vitamin D was less than 15 ng/mL in five of six (three with rickets) in group 1, whereas only one in group 2 had concentrations less than 15 ng/mL. A significantly blunted rise of vitamin D2 above baseline and reduced area under the absorption curve after 1000 IU/kg vitamin D2 were found in group 1 patients compared to group 2 (both p less than 0.01), and five pediatric controls (both p less than 0.01). The peak change and area under the absorption curve for serum 25-OH vitamin D3 from baseline after 10 micrograms/kg 25-OH vitamin D3 were significantly reduced for group 1 (both at least p less than 0.05) and group 2 compared to controls (both p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Biliary Atresia↗
PubMed2004

Vitamin D2 is much less effective than vitamin D3 in humans.

Vitamins D(2) and D(3) are generally considered to be equivalent in humans. Nevertheless, physicians commonly report equivocal responses to seemingly large doses of the only high-dose calciferol (vitamin D(2)) available in the U.S. market. The relative potencies of vitamins D(2) and D(3) were evaluated by administering single doses of 50,000 IU of the respective calciferols to 20 healthy male volunteers, following the time course of serum vitamin D and 25-hydroxyvitamin D (25OHD) over a period of 28 d and measuring the area under the curve of the rise in 25OHD above baseline. The two calciferols produced similar rises in serum concentration of the administered vitamin, indicating equivalent absorption. Both produced similar initial rises in serum 25OHD over the first 3 d, but 25OHD continued to rise in the D(3)-treated subjects, peaking at 14 d, whereas serum 25OHD fell rapidly in the D(2)-treated subjects and was not different from baseline at 14 d. Area under the curve (AUC) to d 28 was 60.2 ng.d/ml (150.5 nmol.d/liter) for vitamin D(2) and 204.7 (511.8) for vitamin D(3) (P < 0.002). Calculated AUC(infinity) indicated an even greater differential, with the relative potencies for D(3):D(2) being 9.5:1. Vitamin D(2) potency is less than one third that of vitamin D(3). Physicians resorting to use of vitamin D(2) should be aware of its markedly lower potency and shorter duration of action relative to vitamin D(3).

Adult↗
PubMed2001

Intakes of carotenoids, vitamin C, and vitamin E and MS risk among two large cohorts of women.

BACKGROUND: Antioxidant nutrients may reduce the risk of MS. In a recent case-control study, vitamin C intake was significantly inversely associated with MS risk among women. However, no prospective data are available. OBJECTIVE: To examine prospectively the associations of intakes of carotenoids, vitamin C, and vitamin E with the risk of MS among women. METHODS: The authors documented the occurrence of definite and probable MS within two large cohorts of women who completed detailed and validated semiquantitative food frequency questionnaires. One cohort (Nurses' Health Study) comprised 81,683 women aged 38 to 63 years in 1984, who were followed for 12 years; the other (Nurses' Health Study II) comprised 95,056 women aged 27 to 44 years in 1991, who were followed for 6 years. RESULTS: The authors documented a total of 214 cases of MS. After adjustments for age, latitude of birthplace, pack-years of smoking, and total energy intake, the pooled multivariate relative risks (95% CIs) comparing women in the highest quintile with those in the lowest quintile were 1.1 (0.7 to 1.7) for alpha-carotene, 1.1 (0.7 to 1.6) for beta-carotene, 1.4 (0.8 to 2.2) for beta-cryptoxanthin, 1.0 (0.6 to 1.5) for lycopene, 1.0 (0.7 to 1.6) for lutein/zeaxanthin, 1.4 (0.9 to 2.1) for total vitamin C, 1.3 (0.9 to 2.0) for dietary vitamin C, 0.8 (0.6 to 1.3) for total vitamin E, and 0.9 (0.6 to 1.4) for dietary vitamin E. The authors found no associations between intakes of fruits and vegetables and risk of MS. Use of vitamin C, vitamin E, and multivitamin supplements was also unrelated to risk of MS. CONCLUSIONS: These findings do not support hypotheses relating higher intakes of dietary carotenoids, vitamin C, and vitamin E to reduced risk of MS in women.

Adult↗
PubMed2002

Effects of dietary supplementation with vitamin C or vitamin E on cardiac lipid peroxidation and growth performance in broilers at risk of developing ascites syndrome.

OBJECTIVE: To assess effects of high dietary amounts of vitamin C or vitamin E and oxidative stress on the heart and growth performance of broilers maintained at an altitude of 2,200 m above sea level. ANIMALS: 360 chicks (1-day-old broilers). PROCEDURE: Birds were randomly assigned to 3 groups (120 chicks/group). Each group of birds was fed a specific diet (control group, basal diet containing 12 mg of vitamin E (DL-alpha-tocopherol acetate)/kg of feed without additional ascorbic acid; vitamin E group, basal diet supplemented with 75 mg of vitamin E/kg of feed; and vitamin C group, basal diet supplemented with 400 mg of ascorbic acid/kg of feed) throughout the entire 7 weeks of the study. Feed consumption and body weight of chicks were recorded on a weekly basis. Nine randomly selected birds from each group were euthanatized each week. Remaining birds were euthanatized at the end of the study. Samples of cardiac tissues were obtained to measure thiobarbituric acid reactive substances (TBARS), an indicator of oxidative stress. RESULTS: Vitamin E-supplemented diets resulted in better growth performance, lower rates of feed conversion, and lower TBARS content. Vitamin C-supplemented diets resulted in lower feed consumption and lower rates of feed conversion. When used separately, neither of the vitamins had any effect on mortality attributable to ascites syndrome. CONCLUSION AND CLINICAL RELEVANCE: It is recommended that diets supplemented with vitamin C, vitamin E, or both be fed to broilers maintained at an altitude of 2,200 m above sea level to improve growth performance.

Altitude↗
PubMed2005

[The effect of combined use of vitamin C, vitamin E, and ibuprofen on flap viability: an experimental study].

OBJECTIVES: Many studies have been carried out to investigate the individual effects of vitamin C, vitamin E, and ibuprofen on flap viability, with favorable results. This study aimed to determine the effect of combined use of these agents on flap viability. DESIGN AND METHODS: Sixty Wistar rats weighing 250-300 grams were divided into six groups, equal in number, to receive saline solution (group 1, control), vitamin C (group 2), vitamin E (group 3), vitamin C and E (group 4), ibuprofen (group 5), and vitamin C, vitamin E, and ibuprofen (group 6). Following ketamine anesthesia, a caudally based reverse McFarlane flap on the back of the rats, 3x10 cm in size, was elevated and sutured back. The agents were administered intraperitoneally once daily for seven days, after which viable flap areas were estimated. RESULTS: The percentages of the viable area of the flaps in groups 1, 2, 3, 4, 5, and 6 were 58.0%, 68.1%, 61.4%, 73.4%, 69.1%, and 80.5%, respectively. The use of vitamin C, vitamin E, and ibuprofen in combination resulted in a significantly greater flap viability compared to individual uses. CONCLUSION: Administering vitamin E and vitamin C together has a greater effect on flap viability than used alone; however, the benefit is the greatest with the addition of ibuprofen.

Animals↗
PubMedDate not supplied

Pathology of experimental vitamin D deficiency in turkeys and the effects of various vitamin D supplements.

One-day-old poults fed a vitamin D3-deficient diet were examined for clinical, biochemical, and morphological changes at 14 days of age. Changes in these parameters were compared at 15.5 and 17 days of age after one of the following vitamin D-replacement therapies was provided: water-soluble vitamin-mineral packs that contained vitamin D3; vitamin D3 in the feed; or vitamin D, 1,25-dihydroxyvitamin D3 in the feed. The vitamin D3-deficient poults were lame and had significant decreases in weight gain and in longitudinal skeletal growth. None of the therapies alleviated all these changes, but clinical lameness subsided in poults provided 1,25-dihydroxyvitamin D3. Calcium concentrations were significantly improved by all therapies. Treatment with vitamin D3 in the feed and water significantly increased 25-hydroxyvitamin D3 concentrations in vitamin D-deficient poults. The growth plate zones, with the exception of the mineralized hypertrophied zone, were all increased in length and not modified by treatment. However, the mineralized hypertrophied zones in the 1,25-dihydroxy-vitamin D3 group and the group receiving vitamin D3 in the water were comparable to that in the controls on day 15.5.

Animal Feed↗
PubMed1980

[Vitamin K and bone metabolism - on the effect of vitamin K deficiency and gamma-carboxyglutamic acid (author's transl)].

Vitamin K was thought to be primarily involved in the production of clotting factors. The recent findings of gamma-carboxyglutamic acid (Gla) - vitamin K-dependent calcium binding amino acid - in various calcified tissues, however, have prompted suggestions that vitamin K may play an important role in calcification mechanism. The present study was designed to investigate the relation between vitamin K and calcification. Morphological, biomechanical and biochemical analyses were undertaken on bones from vitamin K deficient rats raised on vitamin K deficient diet combined with administration of warfarin for three weeks. The Gla-containing proteins were extracted with EDTA from rat or bovine bones, partially isolated with gel filtration, and amino acid analysis was done. Gross roentgenographical and histological abnormalities were not observed in bones from vitamin K deficient rats in which prothrombin level was reduced to about 20 percent. There were no significant differences in values of Young's modulus, which were measured by three-point bending test, between vitamin K deficient and normal bones. No considerable alteration were noted in the protein, calcium or magnesium content of vitamin K deficient bone. Gla content of vitamin K deficient rat bone (per 1,000 residues of glutamic acid) was reduced by approximately 9% compared with that of normal rat bone. This observation supports the hypothesis that Gla biosynthesis in bone may be dependent on vitamin K. Calcium binding property of bovine bone Gla-containing protein was confirmed by the equilibrium dialysis procedure. Moderate amount of hydroxyproline was present in the Gla-containing proteins extracted from rats or bovine bones. It seems possible that biosynthesis of collagen and Gla protein of bone are somehow related, possibly at the level of procollagen. Further investigation is necessary to isolate Gla protein and clarify the correlation between collagen molecule and Gla protein biosynthesis.

1-Carboxyglutamic Acid↗
PubMed1996

Comparative effectiveness of vitamin D3 and dietary vitamin E on peroxidation of lipids and enzymes of the hepatic antioxidant system in Sprague--Dawley rats.

The vitamin D-endocrine system has mostly been studied for its role in calcium and phosphorus metabolism and its possible role as an antioxidant has been neglected. This study attempts to elucidate the antioxidative properties of the prohormone with respect to vitamin E, a membrane antioxidant. Results herein show that D3 treatment brought about similar reduction in the extent of lipid peroxidation and induction in superoxide dismutase (SOD) activity, as with vitamin E supplementation. While selenium dependent glutathione peroxidase (Sedep. GPx) activity reflected no change with vitamin D3 treatment, total GPx activity was more significantly influenced by vitamin D3 than by vitamin E. The glutathione (GSH) content in the experimental rats also reflected similar changes. Vitamin E supplementation caused 8.57% increase in glutathione reductase (GR) activity, while vitamin D3 decreased the concerned enzymes activity by 11.11%. Vitamin D3 treatment also caused 25% increase in glucose 6-phosphate dehydrogenase (G6PD) activity. These data thus suggest that vitamin D3 may function as an antioxidant in the liver in vivo and illustrate an effectiveness higher than that observed with vitamin E supplementation.

Animals↗