Low Concentrations Of Vitamin Research Articles

Surface Cross-linked UHMWPE: A Low Wear Material with Very High Fatigue Strength

Low fatigue strength of highly cross-linked ultrahigh molecular weight polyethylene (UHMWPE) causes concern about the increased risk of fracture. We describe a wear and oxidation-resistant UHMWPE with high fatigue strength by limiting cross-linking to the articular surface. We obtained cross-linking in the surface by molding implants with a low concentration of vitamin E on the surface and high concentration in the bulk prior to irradiation using the ability of vitamin E to hinder cross-linking in UHMWPE as a function of concentration.

Circulating Plasma Antioxidants, Inflammatory Markers and Asymptomatic Carotid Atherosclerosis in End-Stage Renal Disease Patients: A Case Control Study

Few studies have been conducted on the relationship between antioxidant plasma vitamin concentrations, inflammatory markers and carotid atherosclerosis with inconclusive results in endstage renal disease (ESRD) patients. A case-control study was performed to investigate the relationship between plasma antioxidant concentrations, inflammatory markers, and carotid intima-media thickness (CIMT) in healthy subjects and in patients undergoing hemodialysis (HD). We enrolled 40 subjects (20 healthy, 20 with ESRD) asymptomatic for carotid atherosclerosis. After carotid ultrasound investigation (CUI), medical history data, physical examination, venous blood samples were collected. These were analyzed for concentrations of antioxidant vitamins (A, E), carotenoids (lycopene, beta-carotene), inflammatory markers (C-reactive protein, fibrinogen), and lipid profile. Low concentrations of vitamin A, vitamin E, lycopene, and beta-carotene were significantly associated with carotid atherosclerosis in patients with ESRD (p less than 0.001). In addition, high concentration of low density lipoprotein cholesterol and total cholesterol (p less than 0.01), C-reactive protein and fibrinogen (p less than 0.001) were also associated with carotid atherosclerosis, while other laboratory parameters considered (high density lipoprotein cholesterol and triglycerides) were not significantly associated with carotid atherosclerosis. A regular intake of foods rich in antioxidant vitamins with low fat concentrations may slow the progression of atherosclerotic process in this group of patients.

Th17 mediators and vitamin D status

In their study on Th1 and Th17 hypercytokinemia in severe pandemic influenza, Bermejo-Martin and colleagues [1] observed significantly elevated levels of IL-17 and particularly IL-6 in critically ill patients. They also reported that up to 50% of critical care patients studied were obese. Correale and colleagues [2] indicate that activated vitamin D enhances the development of IL-10-producing cells and reduces the number of IL-6- and IL-17- secreting cells. Studies show that obese and overweight individuals are more likely to have an inadequate vitamin D status [3,4]. According to Louie and colleagues [5], diabetes and obesity were the most frequently identified underlying conditions in fatal pandemic 2009 influenza A (H1N1) infection cases older than age 20 years world wide. In addition, obese people usually have high calorie and low nutritional value diets. Aasheim and colleagues [6] showed that low concentrations of vitamin B-6, vitamin C, 25-hydroxyvitamin D, and vitamin E adjusted for lipids are prevalent in morbidly obese Norwegian patients seeking weight-loss treatment. It would be interesting to see if any of the critical cases observed in the study by Bermejo-Martin and colleagues were insufficient or deficient in vitamin D and/or other nutrients relevant for intracellular signaling involved in inflammation. If vitamin D plays a role in human general capacity to deal with infection and other diseases, then an increase in Th17 mediators in severe pandemic influenza patients could be, at least in part, related to vitamin D insufficiency/deficiency.

Vitamin K in Parenteral Nutrition

Vitamin K (as phylloquinone and menaquinones) is an essential cofactor for the conversion of peptide-bound glutamate to gamma-carboxy glutamic acid (Gla) residues in a number of specialized Gla-containing proteins. The only unequivocal deficiency outcome is a bleeding syndrome caused by an inability to synthesize active coagulation factors II, VII, IX, and X, although there is growing evidence for roles for vitamin K in bone and vascular health. An adult daily intake of about 100 microg of phylloquinone is recommended for the maintenance of hemostasis. Traditional coagulation tests for assessing vitamin K status are nonspecific and insensitive. Better tests include measurements of circulating vitamin K and inactive proteins such as undercarboxylated forms of factor II and osteocalcin to assess tissue and functional status, respectively. Common risk factors for vitamin K deficiency in the hospitalized patient include inadequate dietary intakes, malabsorption syndromes (especially owing to cholestatic liver disease), antibiotic therapy, and renal insufficiency. Pregnant women and their newborns present a special risk category because of poor placental transport and low concentrations of vitamin K in breast milk. Since 2000, the Food and Drug Administration has mandated that adult parenteral preparations should provide a supplemental amount of 150 microg phylloquinone per day in addition to that present naturally, in variable amounts, in the lipid emulsion. Although this supplemental daily amount is probably beneficial in preventing vitamin K deficiency, it may be excessive for patients taking vitamin K antagonists, such as warfarin, and jeopardize their anticoagulant control. Natural forms of vitamin K have no proven toxicity.

Vitamin C deficiency in early postnatal life impairs spatial memory and reduces the number of hippocampal neurons in guinea pigs

BackgroundThe neonatal brain is particularly vulnerable to imbalances in redox homeostasis because of rapid growth and immature antioxidant systems. Vitamin C has been shown to have a key function in the brain, and during states of deficiency it is able to retain higher concentrations of vitamin C than other organs. However, because neurons maintain one of the highest intracellular concentrations of vitamin C in the organism, the brain may still be more sensitive to deficiency despite these preventive measures. ObjectiveThe objective was to study the potential link between chronic vitamin C deficiency and neuronal damage in newborn guinea pigs. DesignThirty 6- to 7-d-old guinea pigs were randomly assigned to 2 groups to receive either a vitamin C–sufficient diet or the same diet containing a low concentration of vitamin C (but adequate to prevent scurvy) for 2 mo. Spatial memory was assessed by the Morris Water Maze, and hippocampal neuron numbers were quantified by stereologic techniques. ResultsThe results showed a reduction in spatial memory (P < 0.05) and an increased time to first platform hit (P < 0.05) in deficient animals compared with controls. The deficient animals had a lower total number of neurons in hippocampal subdivisions (dentate gyrus, cornu ammonis 1, and cornu ammonis 2–3) than did the normal controls (P < 0.05). ConclusionsOur data show that vitamin C deficiency in early postnatal life results in impaired neuronal development and a functional decrease in spatial memory in guinea pigs. We speculate that this unrecognized effect of vitamin C deficiency may have clinical implications for high-risk individuals, such as in children born from vitamin C–deficient mothers.

Vitamin D Supplementation and Reduced Risk of Preeclampsia in Nulliparous Women

A recent study showed that nulliparous women who develop preeclampsia had low concentrations of vitamin D in serum sampled in midpregnancy. The aim of the present study was to estimate the association between intake of vitamin D during pregnancy and the risk of preeclampsia in 23,423 nulliparous pregnant women taking part in the Norwegian Mother and Child Cohort Study. Participating women answered questionnaires at gestational week 15 (general health questionnaire), at week 22 (food frequency questionnaire), and at week 30 (general health questionnaire). Pregnancy outcomes were obtained from the Medical Birth Registry. Nutrient intake was calculated from foods and dietary supplements. We estimated relative risks as odds ratios, and controlled for confounding with multiple logistic regression. The odds ratio of preeclampsia for women with a total vitamin D intake of 15-20 microg/d compared with less than 5 microg/d was 0.76 (95% confidence interval = 0.60-0.95). Considering only the intake of vitamin D from supplements, we found a 27% reduction in risk of preeclampsia (OR = 0.73 [0.58-0.92]) for women taking 10-15 microg/d as compared with no supplements. No association was found between intake of vitamin D from the diet alone and the occurrence of preeclampsia. These findings are consistent with other reports of a protective effect of vitamin D on preeclampsia development. However, because vitamin D intake is highly correlated with the intake of long chain n-3 fatty acids in the Norwegian diet, further research is needed to disentangle the separate effects of these nutrients.

Hypocalcemia in Infants and Children

Hypocalcemia in Infants and Children

Vitamin contents of eggs that produce larvae showing a high survival rate in the Japanese eelAnguilla japonica

This paper describes the relationship between the egg vitamin concentrations and the egg quality in the Japanese eel Anguilla japonica. No notable relation was found between any vitamin and the fertilization rate. Hatching and survival rates of larvae, however, significantly increased with an elevated level of egg vitamin C (VC). In contrast to VC, the relation between vitamins E (VE) and A (VA) concentrations and survival rate showed a clear peak, with a reduced survival rate at both higher and lower vitamin concentrations. The ratio of VE to lipid or highly unsaturated fatty acid (HUFA) in eggs positively correlated with hatching and survival rates of larvae. High-quality (HQ) eggs were determined as eggs that produced larvae having a survival rate higher than 80% at 8 days post hatch, and low-quality (LQ) eggs were determined as eggs that did not hatch. The level of VC of HQ was significantly higher than LQ. The results of this study suggest that HQ eggs, which produce larvae having a high survival rate, must have high levels of VC and VE/HUFA ratio and contain optimum levels of VA and VE in Japanese eel.

Plasma Antioxidants and Asymptomatic Carotid Atherosclerotic Disease

Background: Atherosclerosis remains clinically mute for a long time and frequently manifests itself with an acute cardiovascular event. The possibility of detecting this disease in a subclinical phase and reducing or reversing its progression is an issue of relevance. Published studies on the association between antioxidant vitamins and carotenoids and carotid intima-media thickness (CIMT) have been inconclusive. Methods: We enrolled 220 consecutive, asymptomatic participants. After carotid ultrasound investigation, a medical history was taken, a physical examination was performed and venous blood samples were collected. Venous blood samples were analyzed for concentrations of antioxidant vitamins and carotenoids. Results: Low concentrations of vitamin A (p < 0.01), vitamin E (p < 0.001), lycopene (p < 0.01) and β-carotene (p < 0.001) were significantly associated with carotid atherosclerosis (CIMT ≧0.8 mm). In addition, marginally higher body mass index, plasma haemoglobin and high-density lipoprotein cholesterol were also associated with carotid atherosclerosis, while other laboratory parameters considered in this study (total cholesterol, low-density lipoprotein cholesterol, triglycerides and C-reactive protein) were not significantly associated with carotid atherosclerosis. Conclusions: Low plasma concentrations of antioxidant vitamins (A, E, β-carotene) and lycopene were associated with early carotid atherosclerotic lesions as measured by CIMT. Regular intake of foods rich in lycopene and antioxidant vitamins may slow the progression of atherosclerosis.

Coffee Consumption and Circulating B-Vitamins in Healthy Middle-Aged Men and Women

Coffee consumption has been associated with several risk factors for coronary heart disease, including increased cholesterol, increased blood pressure, and increased plasma total homocysteine (tHcy). tHcy is determined by several B-vitamins. However, reports about the association between coffee intake and B-vitamin status are few. We measured plasma B-vitamins and tHcy in a cohort of 10,601 healthy, middle-aged Norwegian men and women. Information about lifestyle factors, including coffee consumption, smoking, alcohol use, height, and weight, was obtained by interview. Coffee consumption was dose-dependently associated with reduced plasma B-vitamin concentrations. Compared with coffee abstainers, individuals drinking >or=4 cups/day had 11.7% (P < 0.001), 14.1% (P < 0.001), and 5.5% (P = 0.01) lower plasma concentrations of folate, pyridoxal phosphate, and riboflavin, respectively, and the mean tHcy concentration was 6.8% (P < 0.001) higher. Quantile regression analysis showed essentially no difference in B-vitamin concentrations between coffee consumption categories at low vitamin concentrations but a progressive increase in the difference at higher concentrations. This pattern of differences (effect profile) was found independently of smoking status, alcohol intake, and sex. The decrease in folate explained approximately half of the increase in tHcy. Coffee consumption was associated with reduced circulating B-vitamin concentrations. The observed effect profiles indicated that coffee consumption preferentially affected the upper, but not the lower, part of the B-vitamin concentration distributions. We hypothesize that coffee consumption may increase the loss of surplus B-vitamins by excretion in urine.

Trace concentrations of vitamin E protect radiation crosslinked UHMWPE from oxidative degradation

The effect of very low concentrations of Vitamin E on the stability and mechanical behavior of UHMWPE remains unknown. We tested the hypothesis that the oxidation resistance of Vitamin E-blended UHMWPE would be influenced by trace doses of antioxidant, resin, and radiation treatment. Trace concentrations (< or =500 ppm w/w%) of alpha-tocopherol (Vitamin E) were blended separately with GUR 1020 and 1050 resins and molded into disks. From each disk, three groups of 10 mm thick blocks were machined: (1) no irradiation (control); (2) 30 kGy of gamma irradiation in nitrogen; and (3) 75 kGy of gamma irradiation in air. Specimens were subjected to three aging protocols: (a) no aging (control); (b) two weeks and (c) four weeks of accelerated aging in accordance with ASTM F 2003 (i.e., 70 degrees C and 5 atm oxygen). The minimum concentration of Vitamin E needed to stabilize UHMWPE during our accelerated tests depended upon the method of radiation processing. For the 30 and 75 kGy irradiated materials, the addition of 125 ppm or more Vitamin E was sufficient to maintain baseline mechanical and chemical properties through two weeks of accelerated aging. For these groups, the addition of 375 ppm or 500 ppm, respectively, was necessary to maintain baseline mechanical and chemical properties throughout the four-week accelerated aging period. UHMWPE resin molecular weight did not have an effect on oxidation behavior. The results of this experiment therefore supported our hypotheses that trace concentrations of Vitamin E, coupled with radiation treatment-but not resin grade-influence the mechanical and oxidative degradation behavior of UHMWPE.

Effects of injectable vitamins A, D, E and C on the health and growth rate of feedlot cattle destined for the Australian domestic market

To examine the effects of injectable vitamins A, D and E at feedlot entry on health and growth rate and the effects of injectable vitamin C at the time of treatment for bovine respiratory disease (BRD) on cattle health. Systematic allocation of 2465 cattle at feedlot entry to: a commercial vitamin A, D and E preparation at the label dose rate; commercial vitamin A, D and E at twice the label dose rate; a formulation with no vitamin D, a lower concentration of vitamin A and a higher concentration of vitamin E; and the oil-based carrier alone at volumes corresponding to the above treatments. Comparisons of growth rate, disease and mortality were made between the groups at the conclusion of the feeding period. In a separate experiment, 176 cattle were alternately administered injectable vitamin C at the time of treatment for BRD, or were not injected with vitamin C, and mortality was compared between the groups. There were no differences between cattle administered vitamin A, D and E at feedlot entry and the controls in growth rate (P=0.11), all diseases (P=0.99), BRD (P=0.60) or mortalities (P=0.95). Cattle treated with the higher vitamin E and lower vitamin A preparation had a higher (P=0.02) incidence of anorexia than the other groups. Fewer cattle treated with 5 g of vitamin C by intramuscular injection at the time of treatment with antibiotics for BRD subsequently died (P=0.04). The routine injection of cattle with vitamins A, D and E at feedlot entry is unlikely to result in improvements in health and growth rate where cattle are provided with these vitamins in their diets at concentrations equal to the National Research Council recommendations. Mortality rate in cattle diagnosed with BRD may be reduced by intramuscular injection of vitamin C at the time of treatment with antibiotics.

Vitamin status in morbidly obese patients: a cross-sectional study

Background:Morbid obesity is associated with low circulating concentrations of 25-hydroxyvitamin D. Few data on the concentrations of other vitamins in morbidly obese patients are available. Objective:The objective was to compare serum and blood vitamin concentrations in morbidly obese patients with those in healthy subjects. Design:In 2 public hospital departments (southeast Norway), we prospectively examined 110 consecutive patients (76 women) and 58 healthy controls (30 women) not taking multivitamin supplements. Patients and controls did not differ significantly in age or ethnicity. The mean (±SD) body mass index (in kg/m2) was 45 ± 7 in the patients and was 24 ± 3 in the controls. Patients with vitamin concentrations lower than 2 SD below the sex-specific mean in controls were considered to have inadequate vitamin status. Results:The morbidly obese women and men had significantly lower concentrations of vitamin B-6, vitamin C, 25-hydroxyvitamin D, and lipid-standardized vitamin E than did the healthy controls (P < 0.01 for each). The status of these vitamins was inadequate in a substantial proportion of the patients (11–38%). The status of vitamins A, B-1, B-2, and B-12 and of folic acid was adequate in most of the patients (95–100%). A moderately elevated C-reactive protein concentration was associated with lower vitamin A, B-6, and C concentrations. In a multiple regression analysis, concentrations of alkaline phosphatase (inverse relation) and vitamin C were the strongest determinants of serum vitamin B-6 concentrations. Conclusions:Low concentrations of vitamin B-6, vitamin C, 25-hydroxyvitamin D, and vitamin E adjusted for lipids are prevalent in morbidly obese Norwegian patients seeking weight-loss treatment.

Serum Micronutrient Concentrations and Decline in Physical Function Among Older Persons

Maintaining independence of older persons is a public health priority, and identifying the factors that contribute to decline in physical function is needed to prevent or postpone the disablement process. The potential deleterious effect of poor nutrition on decline in physical function in older persons is unclear. To determine whether a low serum concentration of micronutrients is associated with subsequent decline in physical function among older men and women living in the community. Longitudinal study of 698 community-living persons 65 years or older who were randomly selected from a population registry in Tuscany, Italy. Participants completed the baseline examination from November 1, 1998, through May 28, 2000, and the 3-year follow-up assessments from November 1, 2001, through March 30, 2003. Decline in physical function was defined as a loss of at least 1 point in the Short Physical Performance Battery during the 3-year follow-up. Odds ratios (ORs) were calculated for the lowest quartile of each nutrient using the other 3 quartiles combined as the reference group. Two additional and complementary analytical approaches were used to confirm the validity of the results. The mean decline in the Short Physical Performance Battery score was 1.1 point. In a logistic regression analysis that was adjusted for potential confounders, only a low concentration of vitamin E (<1.1 microg/mL [<24.9 micromol/L]) was significantly associated with subsequent decline in physical function (OR, 1.62; 95% confidence interval, 1.11-2.36; P = .01 for association of lowest alpha-tocopherol quartile with at least a 1-point decline in physical function). In a general linear model, the concentration of vitamin E at baseline, when analyzed as a continuous measure, was significantly associated with the Short Physical Performance Battery score at follow-up after adjustment for potential confounders and Short Physical Performance Battery score at baseline (beta = .023; P = .01). In a classification and regression tree analysis, age older than 81 years and vitamin E (in participants aged 70-80 years) were identified as the strongest determinants of decline in physical function (physical decline in 84% and 60%, respectively; misclassification error rate, 0.33). These results provide empirical evidence that a low serum concentration of vitamin E is associated with subsequent decline in physical function among community-living older adults. Clinical trials may be warranted to determine whether an optimal concentration of vitamin E reduces functional decline and the onset of disability in older persons.

Determinants and Associations of Homocysteine and Prothrombotic Risk Factors in Kuwaiti Patients with Cerebrovascular Accident

Objective: The objective ofthis study was to evaluate the determinants and associations of some prothrombotic risk factors in patients with cerebrovascular accidents (CVAs). Subjects and Methods:In this case-control study, plasma total homocysteine (tHcy), lupus anticoagulant, protein C, protein S, activated protein C resistance (APC-R) and antithrombin were measured in 102 patients (60 males and 42 females) and 167 controls (87 males, 80 females). Serum vitamin B₁₂, folate, red cell folate, creatinine, lipid profile and glucose were also determined. Glomerular filtration rate (GFR) was calculated. Results:13 (22%) of the 60 male patients, and 16 (39%) of the 42 female patients had hyperhomocysteinemia. Median (interquartile range) tHcy was higher in male patients [11.22 µmol/l (9.60–15.40)] than female patients [10.05 µmol/l (8.72–17.54)]. On binary logistic regression analysis, the significant (p < 0.05) determinants of tHcy were urea, creatinine and GFR. Comparing patients with control subjects showed that tHcy, age, fasting glucose, urea, serum creatinine, white blood cell count, protein S, APC-R and factor VIII were significantly higher, while protein C, factor II, total cholesterol, high-density lipoprotein cholesterol and low-density lipoprotein cholesterol were significantly lower in patients. Lupus anticoagulant was not associated with tHcy and not detected in patients and controls. Low concentrations of vitamins B₁₂ and folate were not associated with tHcy. Logistic regression analysis showed a significant association of tHcy with CVA (OR = 9.55; p = 0.047) in males in the presence of other traditional CVA risk factors but tHcy is not independently associated with CVA in females. Conclusion:Hyperhomocysteinemia is common in Kuwaiti patients with CVA and tHcy probably interacts with prothrombotic factors (protein C, APC-R and factor VIII) to increase CVA risk. The main determinants, age and GFR markers, should be kept in mind when determining the risk associated with tHcy.

Antioxidant status of Nigerian children with Plasmodium falciparum malaria

We evaluated the antioxidant status of 148 Nigerian children with Plasmodium falciparum malaria. The mean malarial parasitaemia was 4701.05 ± 2160.53/µL. The mean antioxidant concentrations of the infected children were determined for vitamin A (12.16 ± 1 - 16 µg/dL), vitamin C (0.43 ± 0.03 mg/dL), 5 carotenes (40.96 ± 5.38 µg/dL), and vitamin E (0.45 ± 0.03 mg/dL). The control subjects had higher mean concentrations of vitamin A (72.12 ± 3.12 µg/dL), and of the 5 carotenes (132.63 ± 22.45 µg/dL), and these differences were statistically significant (X2 = 42.86, P > 0.05 and X2 = 50.64, P > 0.05, respectively). The mean concentrations of vitamin C (1.22 ± 0.31 mg/dL) and vitamin E (1.03 ± 0.48 mg/dL) in the control children were not statistically significant when compared with their infected children (X2 = 0.34, P 6 years (1176.58 ± 956/µL). The children between 1 - 5 years old had lower concentrations of vitamin A (8.89 ± 3.74 µg/dL) and vitamin C (0.28 ± 0.21 µg/dL), while the concentration of the 5 carotenes (44.54 µg/dL) and of vitamin E (0.50 ± 0.16 µg/dL) was higher in these children. In conclusion, the depressed levels of plasma antioxidants in the P. falciparum-infected children suggested lowered immunity of the children, which may contribute to the morbidity and mortality of malaria in our locality. Key words: Vitamin A, vitamin C, vitamin E, antioxidants, children, Plasmodium falciparum, Nigeria

Combined antioxidant effects of rutin and Vitamin C in Triton X-100 micelles

UV–vis spectra, fluorescence emission spectra and cyclic voltammetric measurements were used to study the influence of Vitamin C on the antioxidant of rutin in Triton X-100 micelles. Rutin can be located in Triton X-100 micelles spontaneously through hydrophobic force, and the binding constant K between rutin and Triton X-100 increases with the rutin concentration. The embedment of two hydroxyl groups on rutin into the more hydrophobic micellar microenvironment makes the oxidation of rutin harder and the radical scavenging activity decrease. With low concentration of Vitamin C, the antioxidant capacity of rutin against hydroxyl radical is enhanced, while that capacity is partly inhibited when the concentration of Vitamin C become higher.

Vitamin B 6 suppresses apoptosis of NM-1 bovine endothelial cells induced by homocysteine and copper

Hyperhomocysteinemia is an important risk factor for atherosclerosis. We previously reported that formation of early atherosclerosis in the rat aorta was associated with hyperhomocysteinemia and reduction of antioxidant activity caused by low concentration of vitamin B 6 in vivo. In the present study, we examined effects of vitamin B 6 on apoptosis of bovine endothelial cells (NM-1 cells) treated with homocysteine and copper. Homocysteine and copper induced extracellular hydrogen peroxide, intracellular ROS and cellular lipid peroxide levels. Cell viability was reduced to 30% compared to that of control cells. On the other hand, pyridoxal treatment as well as EDTA treatment increased viability of NM-1 cells treated with homocysteine and copper to about 60%, and significantly decreased extracellular hydrogen peroxide, intracellular ROS and cellular lipid peroxide levels. The treatment of catalase recovered cell viability and reduced the level of extracellular hydrogen peroxide and intracellular ROS. Cell death by homocysteine and copper was confirmed to be due to apoptosis by evaluation of DNA fragmentation and by TUNEL assay. However, apoptosis of NM-1 cells induced by homocysteine and copper was due to a caspase-independent pathway as it was not inhibited by the caspase inhibitor, Z-VAD-fmk. Apoptosis of NM-1 cells induced by homocysteine and copper accompanied with mitochondrial permeability but not cytochrome c release. These results suggest that pyridoxal treatment suppresses apoptosis of NM-1 cells induced by homocysteine and copper, most likely through antioxidant effects.

Enhanced anaerobic biotransformation of carbon tetrachloride with precursors of vitamin B12 biosynthesis

Relatively low concentrations of Vitamin B(12) are known to accelerate the anaerobic biotransformation of carbon tetrachloride (CT) and chloroform (CF). However, the addition of vitamin B(12) for field-scale bioremediation is expected to be costly. The present study considered a strategy to generate vitamin B(12) by addition of biosynthetic precursors. One of the precursors, porphobilinogen (PB) involved in the formation of the corrin ring, significantly increased the CT biotransformation rates by 2.7-, 8.8- and 10.9-fold when supplemented at 160, 500 and 900 microM, respectively. A positive control with 10 microM of vitamin B(12) resulted in a 5.9-fold increase in the CT-bioconversion rate. PB additions provided high molar yields of inorganic chloride (57% of CT organochlorine), comparable to that obtained with vitamin B(12) supplemented cultures. The primary substrate, methanol, known to induce vitamin B(12) production in methanogens and acetogens, was required for PB to have a significant impact on CT conversion. The observation suggests that PB's role was due to stimulating vitamin B(12) biosynthesis. The present study therefore provides insights on how to achieve vitamin B(12) enhanced rates of CT bioremediation through the use of less complex compounds that are precursors of vitamin B(12). Although PB is a costly chemical, its large impact points to corrin ring formation as the rate-limiting step.

Thyroid function during B-vitamin supplementation of patients on antiepileptic drugs

Objectives: Patients on antiepileptic drugs (AEDs) may have low serum concentrations of thyroxine, with or without a compensatory increment in thyroid-stimulating hormone (TSH). Furthermore, patients on AEDs often have hyperhomocysteinemia and low concentrations of vitamins B 6, B 2 and folate. Previously, an inverse relationship between thyroxine and homocysteine concentrations has been observed. In animals, deficiency of vitamin B 6 has been found to impair the hypophyseal release of TRH. We have studied the effect of B-vitamin supplements on thyroid function in patients on AEDs. Design and methods: Thirty-two patients on AEDs were identified with hyperhomocysteinemia and low folate, B 6 and B 2. They were supplemented with pyridoxine, riboflavin and folic acid for 30 days. Results: At baseline, the patients had low serum concentrations of free thyroxin and slightly elevated TSH. On day 30 of the B-vitamin supplements, homocysteine had decreased, however, the thyroid parameters remained unchanged. Conclusions: Hyperhomocysteinemic patients on AEDs have indications of hypothyroidism, however, supplementation with B-vitamins does not improve their thyroid function.