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At least 1,297 records · Page 72Linked to original sources
PubMed2002

Effect of homocysteine-lowering therapy with folic acid, vitamin B12, and vitamin B6 on clinical outcome after percutaneous coronary intervention: the Swiss Heart study: a randomized controlled trial.

CONTEXT: Plasma homocysteine level has been recognized as an important cardiovascular risk factor that predicts adverse cardiac events in patients with established coronary atherosclerosis and influences restenosis rate after percutaneous coronary intervention. OBJECTIVE: To evaluate the effect of homocysteine-lowering therapy on clinical outcome after percutaneous coronary intervention. DESIGN, SETTING, AND PARTICIPANTS: Randomized, double-blind placebo-controlled trial involving 553 patients referred to the University Hospital in Bern, Switzerland, from May 1998 to April 1999 and enrolled after successful angioplasty of at least 1 significant coronary stenosis (> or = 50%). INTERVENTION: Participants were randomly assigned to receive a combination of folic acid (1 mg/d), vitamin B12 (cyanocobalamin, 400 micro g/d), and vitamin B6 (pyridoxine hydrochloride, 10 mg/d) (n = 272) or placebo (n = 281) for 6 months. MAIN OUTCOME MEASURE: Composite end point of major adverse events defined as death, nonfatal myocardial infarction, and need for repeat revascularization, evaluated at 6 months and 1 year. RESULTS: After a mean (SD) follow-up of 11 (3) months, the composite end point was significantly lower at 1 year in patients treated with homocysteine-lowering therapy (15.4% vs 22.8%; relative risk [RR], 0.68; 95% confidence interval [CI], 0.48-0.96; P =.03), primarily due to a reduced rate of target lesion revascularization (9.9% vs 16.0%; RR, 0.62; 95% CI, 0.40-0.97; P =.03). A nonsignificant trend was seen toward fewer deaths (1.5% vs 2.8%; RR, 0.54; 95% CI, 0.16-1.70; P =.27) and nonfatal myocardial infarctions (2.6% vs 4.3%; RR, 0.60; 95% CI, 0.24-1.51; P =.27) with homocysteine-lowering therapy. These findings remained unchanged after adjustment for potential confounders. CONCLUSION: Homocysteine-lowering therapy with folic acid, vitamin B12, and vitamin B6 significantly decreases the incidence of major adverse events after percutaneous coronary intervention.

Angioplasty, Balloon, Coronary↗
PubMed1986

Lipoprotein cholesterol, vitamin A, and vitamin E in an alcoholic population.

Elevated alcohol consumption is associated with an increased risk of cancer. Reasons for this association are not well established but may relate to alterations in cholesterol, vitamin A (carotene and retinol), and vitamin E metabolism, since low levels of these factors have been linked to risk of cancer. Blood levels of cholesterol, carotene, retinol, and vitamin E were determined in 192 male alcoholics entering into an alcohol detoxification program. Compared to nonalcoholic populations, their cholesterol (187 mg/dl) and carotene (94 micrograms/dl) concentrations were markedly reduced at entrance; however, abstinence of 33 days returned both to normal levels. In contrast, the retinol and vitamin E levels were within the normal range at baseline and remained relatively stable throughout rehabilitation. Of particular interest was that the low density lipoprotein cholesterol was highly correlated with carotene (r = +0.40, whites, r = +0.54, blacks). The results suggest that alterations in the metabolism of cholesterol and carotene, due to alcohol intake, may partially account for the relationship of alcohol to increased cancer risk.

Alcoholism↗
PubMed1995

Determination of vitamin A, vitamin E, and their esters in tablet preparations using supercritical fluid extraction and HPLC.

A rapid and precise method for the isolation of vitamins A and E and their acetate or palmitate esters from table matrices was developed using supercritical fluid extraction (SFE). The vitamins were analyzed by nonaqueous reversed-phase high-performance liquid chromatography after a 15-min extraction of the dosage form with supercritical carbon dioxide at 40 degrees C and at a pressure of 250 atm. A quantitative comparison of SFE with an established liquid extraction procedure was performed on commercial tablet formulations. Vitamin recoveries of over 95.6% compared with conventional liquid extraction were achieved by the SFE technique with a much shorter sample preparation time (15 min vs 2h). Moreover, the automated SFE process minimized the number of sample handling operations, drastically reduced the consumption of harmful solvents, and provided mild extraction conditions for the analysis of the labile vitamins. The described SFE method is suitable for quality control analyses of pharmaceutical tablets.

Chromatography, High Pressure Liquid↗
PubMed2002

Effects of vitamin K2, vitamin D, and calcium on the bone metabolism of rats in the growth phase.

Using 168 female Sprague-Dawley rats, we determined whether the peak bone mass could be increased, and which drugs would be effective in suppressing the rate of decrease in bone mass by continuous administration from childhood. At the age of 3 months, these 168 rats were divided into five groups depending on the type of diet that they were fed (control, regular; group A, vitamin K2; group B, vitamin D; group C, high calcium; group D, vitamins D and K2 and high calcium) and kept to the age of 16 months. Dual-energy X-ray absorptiometry (DXA) was used to measure the bone mineral density of the femoral epiphysis and microcomputed tomography (CT) to analyze its fine structure. The average bone mass increased rapidly with age and reached a peak at the age of 8 months. Peak bone mass for the four drug administration groups was higher than that for the control group. Among these four groups, the peak bone mass was the highest in group C and the rate of decrease the smallest in group D. The results of the present animal study suggest that the peak bone mass of humans can be raised by consuming sufficient amounts of vitamins K2 and D and calcium continuously from childhood, and that this diet will suppress the rate of decrease in bone mass, thus ultimately preventing bone fractures caused by osteoporosis.

Animals↗
PubMed1987

Vitamin E remains the major lipid-soluble, chain-breaking antioxidant in human plasma even in individuals suffering severe vitamin E deficiency.

The chain-breaking (peroxyl radical-trapping) antioxidant activity of plasma obtained from several patients with a very severe vitamin E deficiency has been measured. The total chain-breaking antioxidant activity in lipid extracts has been shown to be approximately equal to the concentration of vitamin E. For whole plasma there is no significant difference in the concentrations of water-soluble, chain-breaking antioxidants between the E-deficient patients and healthy adults. It is concluded that even in cases of very severe vitamin E deficiency the requirement for this vitamin is not met by some other exogenous or endogenous antioxidant.

Antioxidants↗
PubMed1984

The effect of intravenous vitamin E and menadiol sodium diphosphate on vitamin K dependent clotting factors.

During a Phase I study of intravenous vitamin E-free alcohol (all-rac-alpha-tocopherol or Ephynal) in patients with neuroblastoma, we noticed a bleeding diathesis in two patients receiving 2300 mg/m2 daily for four or more days in succession. Both blood prothrombin time and accelerated partial thromboplastin times were prolonged. These spontaneously returned to normal levels three days after interrupting vitamin E infusions. It was also noted that factors VII, IX and X were decreased, which corresponded with the prolonged PT and APTT. It was found that by infusing menadiol sodium diphosphate just prior to the vitamin E, these inhibiting effects on procoagulant factors could be abrogated and high dosages of vitamin E-free alcohol safely given.

Blood Coagulation Factors↗
PubMed1992

Evaluation of vitamin D-binding protein and vitamin D metabolite loss in children on continuous ambulatory peritoneal dialysis.

We measured the serum concentration of vitamin D-binding protein (DBP) in children with chronic renal failure (CRF). We also evaluated the relationships between the peritoneal loss of vitamin D metabolites, DBP and albumin in nine children on continuous ambulatory peritoneal dialysis (CAPD). The serum levels of DBP in children with CRF were significantly higher than in normal children. The mean serum DBP level in CRF children undergoing CAPD was slightly lower than in CRF patients who were not on dialysis. In patients on CAPD, the peritoneal loss of 25-hydroxyvitamin D (25OHD) showed a significant positive correlation with the DBP concentration in the dialysate (r = 0.855, P less than 0.005). In contrast, the peritoneal loss of 1,25-dihydroxyvitamin D (1,25(OH)2D) showed a significant correlation with the loss of albumin in the dialysate (r = 0.779, P less than 0.01). The synthesis of 1,25(OH)2D3 is reduced in advanced renal failure, and the peritoneal losses of the active vitamin D sterols in patients on CAPD may aggravate this deficiency. We recommend that supplementation of active form of vitamin D, such as 1 alpha-hydroxyvitamin D3 or 1,25(OH)2D3, is important in CAPD patients, particularly those with elevated peritoneal loss of DBP and/or albumin.

Adolescent↗
PubMed2005

Determination of plasma Vitamin K by high-performance liquid chromatography with fluorescence detection using Vitamin K analogs as internal standards.

A HPLC fluorescence determination method for Vitamin K derivatives (Vitamin K(1), phylloquinone, PK and K(2), menaquinones, MK-4 and MK-7) using post-column reduction and internal standards was developed. Selectivity and reproducibility were increased by optimized chromatography conditions and satisfactory precision and accuracy were attained by using synthetic internal standards. After addition of internal standards to plasma samples, lipids were extracted with ethanol and hexane. Chromatography was performed by isocratic reverse phase separation on a C18 column. Vitamin K derivatives were detected at 430 nm with excitation at 320 nm for MK-4 and 240 nm for PK and MK-7. The detection limits for MK-4, PK and MK-7 were 4, 2 and 4 pg, respectively. The recoveries of MK-4, PK and MK-7 were greater than 92% and the inter- and intra-assay R.S.D. values were 5.7-9.2% for MK-4, 4.9-9.6% for PK and 6.3-19.3% for MK-7. The data showed good correlation between proposed method and LC-APCI/MS method for MK-4 (R(2)=0.988), PK (R(2)=0.979) and MK-7 (R(2)=0.986). The method allows the determination of Vitamin K for evaluating their clinical and nutritional status.

Chromatography, High Pressure Liquid↗
PubMed2003

Synthesis of retinoid vitamin A-vitamin B6 conjugate analogues for antiviral chemotherapy.

The synthesis of retinoid vitamin A-vitamin B(6) conjugate analogues from a vitamin B(6) coenzyme analogue and putative HIV-1 trans-activating transcriptional regulatory protein Tat antagonist (Z)-5(')-O-phosphono-pyridoxylidenerhodanine (B6PR) monosodium salt hemiheptadecahydrate [(Z)-B6PRNa8.5H(2)O] is discussed here. All-trans-retinoic acid (ATRA) is coupled to B6PR by a modified Stork enamine acylation. It results in a product library of more than eight compounds, each with at least one intact all-trans or 13-cis vitamin A double bond system. This yellow oily concentrate mixture was subjected to matrix-assisted laser desorption/ionization-time-of-flight (MALDI-ToF) mass spectrometry (MS), UV/VIS-spectrophotometry, and proton nuclear magnetic resonance spectroscopy (1H-NMR). The chemical structures of six components of the concentrate mixture could be established by combination of these analytical methods. The two main components are 65% 2(')C,3O-(all-trans-retinylidyne)B6PT (B6RA) and 25% 2(')C-(all-trans-retinoyl)B6PT, chemically derived from (5RS)-5-(5(')-O-phosphono-pyridoxyl)-2,4-thiazolidinedione (B6PT). This new retinoid selection could be of further interest in antiviral applications, especially treating conditions caused by RNA viruses like HIV.

Amino Acid Sequence↗
PubMed1987

Chemical reduction system for the detection of phylloquinone (vitamin K1) and menaquinones (vitamin K2).

Both isocratic and gradient elution systems for fluorometric detection of K vitamins after post-column reduction with zinc metal to their hydroquinones are described. The reaction detection system for K vitamins (phylloquinone and menaquinones) in liquid chromatography is based on reduction of K vitamins to their corresponding hydroquinones with zinc metal in the presence of zinc ions. It was found that 95% of the injected quinones (K vitamins) could be reduced to their corresponding hydroquinones with zinc metal compared to 60% reduction for electrochemical detectors. Menaquinones could be detected down to 100 pg with relative ease during gradient elution.

Chromatography, High Pressure Liquid↗
PubMed2001

Hyperlipidemia and reproductive failure in captive-reared alligators: vitamin E, vitamin A, plasma lipids, fatty acids, and steroid hormones.

Blood samples were collected from 26 captive-reared alligators (25 females; one male) and 12 (seven females and five males) wild "nuisance" alligators collected by wildlife personnel in south Louisiana in May 1995. The captive alligators, hatched from artificially incubated eggs in 1972-1973, had received vitamin E supplements during the 3 weeks before the blood sample was collected. Each sample was analyzed for vitamin E (alpha-tocopherol), vitamin A (retinol), total lipid, triacylglycerol, phospholipid, cholesterol, cholesteryl ester, free fatty acids, steroid hormones and a standard clinical blood panel. The fatty acid composition of the plasma lipid fraction was also analyzed. Results indicated that 18 of the captive females and three of the seven wild females were undergoing vitellogenesis, i.e. had elevated plasma estradiol and elevated plasma calcium. Vitellogenic females had higher vitamin E than non-vitellogenic females (77.4 microg/ml vs. 28.6 microg/ml in captive females; 24.0 microg/ml vs. 21 microg/ml in wild females). Plasma retinol was similar in all groups, ranging from 0.5 to 1.4 microg/ml and close to values reported in birds. All lipid fractions, with the exception of cholesteryl ester, were higher in captive alligators than in wild alligators. There were also significant differences in the fatty acid composition of wild and captive alligators. Plasma eicosapentaenoic and docasahexaenoic acid were higher in wild than in captive alligators, whereas linoleic was higher in captive than in wild.

Alligators and Crocodiles↗
PubMed1987

Dosage form and formulation effects on the bioavailability of vitamin E, riboflavin, and vitamin B-6 from multivitamin preparations.

The effects of formulation factors and pharmaceutical dosage form on the bioavailability of RRR-alpha-tocopherol (d-alpha-tocopherol), riboflavin, and pyridoxine hydrochloride were studied after administration of two capsule formulations and a tablet to 12 normal humans. Absorption of RRR-alpha-tocopherol was increased from the Aquabiosorb soft elastic gelatin (SEG) capsule formulation compared with the modified standard-SEG capsule and the commercial tablet. There were no significant differences in bioavailability of riboflavin and pyridoxine hydrochloride between the SEG formulation and the tablet albeit a trend toward consistent absorption was seen from the SEG formulation. The modified-SEG formulation exhibited significantly lower bioavailability for these water-soluble vitamins. The enhanced bioavailability of vitamin E and the trend towards faster and more consistent absorption of riboflavin and vitamin B-6 from the SEG formulation may be related to the surfactant vehicle employed and the attendant wetting properties. The results also suggest ethnic differences in vitamin bioavailability.

Adult↗
PubMed2004

Oxidative stress in abetalipoproteinemia patients receiving long-term vitamin E and vitamin A supplementation.

BACKGROUND: Patients with abetalipoproteinemia develop progressive ataxic neuropathy and retinopathy that are thought to be due, in part, to oxidative damage resulting from deficiencies of vitamins E and A. OBJECTIVE: The goal was to determine the degree of oxidative stress in abetalipoproteinemia patients who had received vitamin E (100 mg/kg) and vitamin A (10 000-15 000 IU/d) since infancy. DESIGN: Ten patients aged 3-25 y were studied. Assessed were plasma carbonyl concentrations as a marker of oxidative damage to proteins; total plasma oxidizability, which was used to evaluate the susceptibility of plasma lipoproteins to oxidation; and cyclic voltammetry, which represents the overall reducing and antioxidant capacity stemming from low-molecular-weight antioxidants in plasma. RESULTS: Concentrations of plasma carbonyls did not differ significantly between patients and control subjects ( +/- SE: 0.5670 +/- 0.031 and 0.5039 +/- 0.0134 nmol/mg protein, respectively). The lag phase of plasma oxidizability was 28.03 +/- 3.16 min in the patients and 24.0 +/- 2.79 min in healthy subjects in whom oxidizability of isolated HDL was measured (NS). Cyclic voltammetry showed a peak potential of 330 +/- 8.3 mV in all samples studied, denoting that the same antioxidants were present in the plasma of the patients and the control subjects. The anodic current of the samples, a measure of the concentration of hydrophilic low-molecular-weight antioxidants, was 5.227 +/- 0.25 and 5.38 +/- 0.20 micro A in the patients and the control subjects, respectively (NS). CONCLUSION: Enhanced oxidative stress is not apparent in the plasma of abetalipoproteinemia patients receiving long-term supplementation with vitamins E and A.

Abetalipoproteinemia↗
PubMed1977

Biological activity of vitamin E compounds and natural materials by the resorption-gestation test, and chemical determination of the vitamin E activity in foods and feeds.

The biological activity of the tocopherols and tocotrienols has been re-examined by the rat resorption-gestation test. The following values have been obtained (with d,l-alpha-tocopheryl acetate = 100%): d-alpha-tocopherol 80%; d,l-alpha-tocopherol 59%; d-alpha-tocopheryl acetate 136%; d-alpha-tocotrienol 13%; d-beta-tocopherol 45%; d-beta-tocotrienol 4%; d-gamma-tocopherol 13%; d-delta-tocopherol less than 0.4%. The possibility of alpha- and gamma-tocopherol being synergists has been tested, but no significant effect was found. The antioxidants BHT and ethoxyquin were without effect on the utilization of alpha-tocopherol by the rat. After chemical determination of the tocopherols and tocotrienols in foods and mixed feeds, these biological activities were used to calculate the vitamin E activity. For two samples of margarine and two samples of mixed feed, the calculated value of the vitamin E activity after chemical determination of the tocopherols and tocotrienols was compared with the value found by direct bioassay, and reasonably good agreement was found. The authors suggest that determination of vitamin E in foods and feeds as a rule should be carried out as a chemical determination of the individual tocopherols and tocotrienols followed by a calculation of the vitamin E activity from the biological activity of the tocopherols and tocotrienols.

Animal Feed↗
PubMed1989

Upper limits of vitamin A in infant formulas, with some comments on vitamin K.

Current Food and Drug Administration (FDA)-approved levels of adequacy and of upper limits in infant formulas for vitamin A are 250 and 750 IU per 100 kcal, respectively. The level of adequacy is generous relative to need. Because vitamin A toxicity has been noted in infants at intakes of 2,100 IU per 100 kcal, an upper limit might well be selected in the range of 750-1,000 IU per 100 kcal for healthy infants. Some children and adults, however, are intolerant of relatively low intakes. The current FDA-approved adequacy level for vitamin K is 4 micrograms per 100 kcal, which also is generous relative to need. An upper limit has not previously been set. Neither single intramuscular doses of phylloquinone that are 100 times the RDA (RDI) for infants nor diets that contain 10-20 times the RDA (RDI) for adults show any adverse effects. Some allergic reactions to injected vitamin K have been reported, however, and menadione, even in low doses, shows significant toxicity in neonates. Thus, although toxicity to phylloquinone is unlikely, it has been suggested that the upper limit of phylloquinone in infant formulas be set at 20 micrograms per 100 kcal, primarily to discourage nutritionally unwarranted supplementation.

Female↗
PubMed2002

Short-term folate, vitamin B-12 or vitamin B-6 supplementation slightly affects memory performance but not mood in women of various ages.

Based on research demonstrating associations between folate, B-12 and B-6 vitamins and cognition and mood, we investigated the effects of short-term supplementation in 211 healthy younger, middle-aged and older women who took either 750 microg of folate, 15 microg of vitamin B-12, 75 mg of vitamin B-6 or a placebo daily for 35 d. In addition, we examined associations between dietary intake of these vitamins and cognition and mood. Usual dietary intake status was estimated using a retrospective, self-report, quantified food frequency questionnaire. Participants completed alternate forms of standardized tests of cognitive processing resources, memory, executive function, verbal ability and self-report mood measures before and after supplementation. Supplementation had a significant positive effect on some measures of memory performance only, and no effect on mood. Dietary intake status was associated with speed of processing, recall and recognition and verbal ability.

Adult↗
PubMed2006

Plasma alpha1-acid glycoprotein can be used to adjust inflammation-induced hyporetinolemia in vitamin A-sufficient, but not vitamin A-deficient or -supplemented rats.

We examined the association between alpha(1)-acid glycoprotein (AGP), all-trans-retinol (retinol), and albumin concentrations in a longitudinal animal model of IL-6-induced inflammation. Vitamin A-sufficient (VAS) male Sprague-Dawley rats were administered recombinant human IL-6 [n = 4, 65 mug/(kg.d)] or PBS (n = 4) continuously for 7 d via osmotic minipumps. Plasma samples were obtained daily and concentrations of retinol, AGP, albumin, and total protein were measured. Compared with both baseline and controls, retinol and albumin decreased (P < 0.05), AGP increased (P < 0.05), and total protein concentrations were unaffected in IL-6-treated rats. In vitamin A-deficient (VAD) rats, AGP concentrations were significantly lower at all time points and increased only to one-third of that in VAS rats. The AGP cut-off value indicative of inflammation was 0.11 g/L (i.e., 95% upper limit of baseline concentrations). After 20.5 h, there was an inverse linear correlation between AGP concentrations and the relative change in retinol to baseline (y = -0.18x + 0.48, r = -0.84, P < 0.001). However, changes in AGP and albumin were not correlated (P = 0.94). The application of this function to retinol concentrations in rats from separate experiments showed that hyporetinolemia cannot be adjusted using plasma AGP in VAD or vitamin A-supplemented rats. In conclusion, correcting inflammation-induced hyporetinolemia using an acute-phase protein requires longitudinally derived data, knowledge of vitamin A status, and a common underlying mechanism of change.

Animals↗
PubMed2006

Microcystin-induced 8-hydroxydeoxyguanosine in DNA and its reduction by melatonin, vitamin C, and vitamin E in mice.

Microcystin LR (MC-LR), a liver-specific toxin synthesized by Microcystis aeruginosa, was investigated. MC-LR initiated reactive oxygen species formation followed by damaging DNA and some other cellular components. We investigated the ability of MC-LR to induce oxidative DNA damage by examining the formation of 8-hydroxydeoxyguanosine (8-OH-dG) using HPLC with electrochemical detection. Melatonin, vitamin C (ascorbate), and vitamin E (as Trolox), all of which are free radical scavengers, markedly inhibited the formation of 8-OH-dG in a concentration-dependent manner. The concentration that reduced DNA damage by 50% (IC(50)) was 0.55, 31.4, and 36.8 microM for melatonin, ascorbate, and Trolox, respectively. The results show that melatonin is 60- and 70-fold more effective than vitamin C or vitamin E, respectively, in reducing oxidative DNA damage. These findings are consistent with the conclusion that melatonin's highly protective effect against microcystin toxicity relates, at least in part, to its direct hydroxyl radical scavenging ability.

8-Hydroxy-2'-Deoxyguanosine↗