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B12 Concentration (b12 + concentration)
Kinds of B12 Concentration Selected AbstractsLow Plasma Vitamin B12 Is Associated With Lower BMD: The Framingham Osteoporosis StudyJOURNAL OF BONE AND MINERAL RESEARCH, Issue 1 2005Katherine L Tucker Abstract Vitamin B12 is important to DNA synthesis and may affect bone formation. We examined the association between this vitamin and BMD in 2576 adults. Men with plasma B12 < 148 pM had significantly lower BMD at the hip, and women at the spine, relative to those with higher B12, and trends were similar for both at all sites. Low vitamin B12 may be a risk factor for low BMD. Introduction: Vitamin B12 is important to DNA synthesis and may affect bone formation. It has been linked to osteoblastic activity in clinical studies and cell culture. Materials and Methods: We examined the relationship between plasma vitamin B12 status and BMD in 2576 adult participants in the Framingham Offspring Osteoporosis Study (1996,2001). BMD was measured by DXA at the hip and spine. Plasma vitamin B12 was measured by radioassay. Mean BMD measures were estimated for four categories of vitamin B12 concentration, based on commonly used cut-offs, using analysis of covariance, adjusted for age, BMI, physical activity score for the elderly (PASE), alcohol use, smoking status, total calcium and vitamin D intake, season of bone measurement, and for women, menopause status and current estrogen use. Further adjustment for protein intake and total homocysteine concentration was also performed. Results: Both men and women with vitamin B12 concentrations <148 pM had lower average BMD than those with vitamin B12 above this cut-off. These differences were significant (p < 0.05) for men at most hip sites and for women at the spine. Significance remained after further adjustment for protein intake and plasma homocysteine. Conclusions: Vitamin B12 deficiency may be an important modifiable risk factor for osteoporosis. [source] Effect of Chronic Alcohol Consumption on Total Plasma Homocysteine Level in RatsALCOHOLISM, Issue 3 2000Felix Stickel Background: Chronic alcoholism in humans is associated with the development of hyperhomocysteinemia, the mechanism of which remains unclear. Among the causes of hyperhomocysteinemia is depletion of folate, vitamin B12, or vitamin B6, Population-based studies indicate that folate is the strongest vitamin determinant of hyperhomocysteinemia and, in most settings, folate supplementation effectively lowers elevated homocysteine levels. However, it is not clear whether folate deficiency is the cause of alcoholrelated hyperhomocysteinemia. Methods: In the present study, 10 male Sprague Dawley® rats were fed ethanol-containing Lieber- DeCarli diets with 13 mg of folic acid per kilogram of diet. This represents a folate intake more than 20 times the basal requirement. Ethanol represented 36% of total energy, which yielded a concentration of 6.2% (vol/vol). The same number of rats were pair-fed with isocaloric control diets that contained an identical level of folate in which ethanol was entirely replaced by maltodextrin. Results: At the end of 4 weeks, alcohol-fed rats did not show any significant reduction in plasma or hepatic folate concentrations, plasma pyridoxal-5,-phosphate concentration, or plasma vitamin B12 concentration. On the other hand, alcohol-fed rats were significantly hyperhomocysteinemic (17.24 ± 4.63 ,mol/liter,p < 0.01) compared to the nonalcohol group (10.73 ± 2.76 ,mol/liter). Alcohol-fed rats also had a significantly lower hepatic S-adenosylmethionine and higher hepatic S-adenosylhomocysteine levels. Conclusions: Chronic alcohol consumption produces hyperhomocysteinemia by a mechanism that is related to interference with one-carbon metabolism, and not through vitamin depletion. [source] Plasma Homocysteine, B Vitamins, and Amino Acid Concentrations in Cats with Cardiomyopathy and Arterial ThromboembolismJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 5 2000M.A. McMichael Arterial thromboembolism (ATE) is a common complication of cats with cardiomyopathy (CM), but little is known about the pathophysiology of ATE. In people, high plasma concentrations of homocysteine and low B vitamin concentrations are risk factors for peripheral vascular disease. In addition, low plasma arginine concentrations have been linked to endothelial dysfunction. The purpose of this study was to compare concentrations of homocysteine, B vitamins, and amino acids in plasma of normal cats to those of cats with CM and ATE. Plasma concentrations of homocysteine, vitamin B6, vitamin B12, folate, and amino acids were measured in 29 healthy cats, 27 cats with CM alone, and 28 cats with both CM and ATE. No differences were found between groups in homocysteine or folate. Mean vitamin B12 concentration (mean ± standard deviation) was lower in cats with ATE (866 ± 367 pg/mL) and cats with CM (939 ± 389 pg/mL) compared with healthy controls (1,650 ± 700 pg/mL; P < .001). Mean vitamin B6 concentration was lower in cats with ATE (3,247 ± 1,215 pmol/mL) and cats with CM (3,200 ± 906 pmol/mL) compared with healthy control animals (4,380 ± 1,302 pmol/mL; P= .005). Plasma arginine concentrations were lower in cats with ATE (75 ± 33 nmol/mL) compared with cats with CM (106 ± 25 nmol/mL) and healthy control animals (96 ± 25 nmol/ mL; P < .001). Vitamin B12 concentration was significantly correlated with left atrial size. We interpret the results of this study to suggest that vitamin B12 and arginine may play a role in CM and ATE of cats. [source] Review article: potential gastrointestinal effects of long-term acid suppression with proton pump inhibitorsALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 6 2000Laine This review examines the evidence for the development of adverse effects due to prolonged gastric acid suppression with proton pump inhibitors. Potential areas of concern regarding long-term proton pump inhibitor use have included: carcinoid formation; development of gastric adenocarcinoma (especially in patients with Helicobacter pylori infection); bacterial overgrowth; enteric infections; and malabsorption of fat, minerals, and vitamins. Prolonged proton pump inhibitor use may lead to enterochromaffin-like cell hyperplasia, but has not been demonstrated to increase the risk of carcinoid formation. Long-term proton pump inhibitor treatment has not been documented to hasten the development or the progression of atrophic gastritis to intestinal metaplasia and gastric cancer, although long-term studies are required to allow definitive conclusions. At present, we do not recommend that patients be tested routinely for H. pylori infection when using proton pump inhibitors for prolonged periods. Gastric bacterial overgrowth does increase with acid suppression, but important clinical sequelae, such a higher rate of gastric adenocarcinoma, have not been seen. The risk of enteric infection may increase with acid suppression, although this does not seem to be a common clinical problem with prolonged proton pump inhibitor use. The absorption of fats and minerals does not appear to be significantly impaired with chronic acid suppression. However, vitamin B12 concentration may be decreased when gastric acid is markedly suppressed for prolonged periods (e.g. Zolllinger,Ellison syndrome), and vitamin B12 levels should probably be assessed in patients taking high-dose proton pump inhibitors for many years. Thus, current evidence suggests that prolonged gastric acid suppression with proton pump inhibitors rarely, if ever, produces adverse events. Nevertheless, continued follow-up of patients taking proton pump inhibitors for extended periods will provide greater experience regarding the potential gastrointestinal adverse effects of long-term acid suppression. [source] Modest increase in plasma homocysteine follows levodopa initiation in Parkinson's diseaseMOVEMENT DISORDERS, Issue 12 2004Padraig E. O'Suilleabhain MB Abstract Levodopa, typically ingested chronically at high daily doses, is predictably methylated by means of a series of reactions using B vitamins, which convert methionine to homocysteine. Elevated total plasma homocysteine (tHcy), a risk factor for dementia, has been found in PD patients using levodopa. We prospectively measured the effects on plasma tHcy and B vitamins of levodopa initiation, and measured the effects of dose changes and of treatment with dopamine agonists and entacapone. We collected paired plasma samples, at baseline and again after several months treatment, from patients initiating levodopa (n = 30), from patients whose levodopa dose was doubled (n = 15), halved or stopped (n = 14), from patients starting or stopping entacapone (n = 15) and from patients initiating or doubling dopamine agonist monotherapy (n = 16). Vitamin B12, folate, and tHcy concentrations were measured. Baseline tHcy concentration of 8.7 (2.8) ,mol/L increased to 10.1 (3.1) ,mol/L (P = 0.004) an average of 94 (range 36 to 200) days after initiation of 604 (240 to 1050) mg/day of L -dopa. Average concentration of vitamin B12 fell from 380 to 291 pmol/ L (P = 0.01). Patients who doubled their daily levodopa dose experienced tHcy elevations from 9.5 to 11.1 ,mol/L (P = 0.05). Levodopa reduction, agonist treatment, and entacapone treatment did not have significant effects. Levodopa elevates tHcy and lowers vitamin B12 concentration to modest degrees. The clinical implications, if any, have not yet been determined. © 2004 Movement Disorder Society [source] Association between hyperhomocysteinaemia and abdominal aortic aneurysmBRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 4 2001S. Caldwell Background: Hyperhomocysteinaemia is associated with occlusive vascular disease. In vitro evidence has demonstrated the induction of a serine elastase by homocysteine in vascular smooth muscle. Anecdotal evidence from case reports and post-mortem studies has suggested an association with abdominal aortic aneurysm (AAA). The aim was to determine the prevalence of hyperhomocysteinaemia in patients with AAA. Methods: Some 120 subjects (60 controls and 60 patients with AAA) were studied prospectively. Epidemiological, clinical and haematological data were collected. Patients were defined as having AAA if ultrasonographic measurement of the aorta was greater than 4·5 cm. Those with evidence of occlusive peripheral vascular disease or an ankle: brachial pressure index lower than 0·8 were excluded. Homocysteine was measured with a commercial high-pressure liquid chromatography analyser. The reference range from age-matched controls was 8·9,14·3 µmol l,1. Results: The median(s.d.) value of homocysteine for patients was significantly higher than that for the control group: 13·1(7·88) versus 10·9(5·07) µmol l,1 (P = 0·03, Mann,Whitney U test). Hyperhomocysteinaemia (homocysteine concentration greater than 14·3 µu;mol l,1) was present in 48 per cent of patients with AAA, compared with 24 per cent of the control population (P < 0·01, ,2 test). There were no significant differences between groups with regard to age, folate levels, vitamin B12 concentration or renal function. Conclusion: These results strongly suggest an association between hyperhomocysteinaemia and AAA. If studies currently ongoing demonstrate a causal relationship between hyperhomocysteinaemia and vascular disease progression, it raises the possibility of treating small aneurysms with vitamin supplementation to slow their growth. © 2001 British Journal of Surgery Society Ltd [source] Low Plasma Vitamin B12 Is Associated With Lower BMD: The Framingham Osteoporosis StudyJOURNAL OF BONE AND MINERAL RESEARCH, Issue 1 2005Katherine L Tucker Abstract Vitamin B12 is important to DNA synthesis and may affect bone formation. We examined the association between this vitamin and BMD in 2576 adults. Men with plasma B12 < 148 pM had significantly lower BMD at the hip, and women at the spine, relative to those with higher B12, and trends were similar for both at all sites. Low vitamin B12 may be a risk factor for low BMD. Introduction: Vitamin B12 is important to DNA synthesis and may affect bone formation. It has been linked to osteoblastic activity in clinical studies and cell culture. Materials and Methods: We examined the relationship between plasma vitamin B12 status and BMD in 2576 adult participants in the Framingham Offspring Osteoporosis Study (1996,2001). BMD was measured by DXA at the hip and spine. Plasma vitamin B12 was measured by radioassay. Mean BMD measures were estimated for four categories of vitamin B12 concentration, based on commonly used cut-offs, using analysis of covariance, adjusted for age, BMI, physical activity score for the elderly (PASE), alcohol use, smoking status, total calcium and vitamin D intake, season of bone measurement, and for women, menopause status and current estrogen use. Further adjustment for protein intake and total homocysteine concentration was also performed. Results: Both men and women with vitamin B12 concentrations <148 pM had lower average BMD than those with vitamin B12 above this cut-off. These differences were significant (p < 0.05) for men at most hip sites and for women at the spine. Significance remained after further adjustment for protein intake and plasma homocysteine. Conclusions: Vitamin B12 deficiency may be an important modifiable risk factor for osteoporosis. [source] G1793A polymorphisms in the methyl- enetetrahydrofolate gene: Effect of folic acid on homocysteine levelsMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 8 2006Sandra Soares Melo Abstract Mutations or polymorphisms in the gene of the enzyme methylenetetrahydrofolate (MTHFR) are associated with hyperhomocysteinemia and possibly with an elevated risk for vascular diseases. A study was conducted on 83 individuals with type 2 diabetes in order to determine the allelic and genotypic frequencies of the G1793A mutation and to assess the effect of folic acid supplementation on plasma homocysteine concentrations. The patients were attended by the Diabetes and Hypertension Program , Balneario Camboriu/SC and received daily supplements containing 1 mg of folic acid for 3 months. DNA was previously extracted from leukocytes and the G1793A mutation was detected by PCR-RFLP. Blood samples were collected during the basal period and after supplementation for the determination of homocysteine by HPLC, and of folic acid and vitamin B12 by RIA. The allele frequency for the G1793A mutation was 3.01% and no homozygous individuals with mutant alleles were detected. Hyperhomocysteinemia was diagnosed in 27.71% of the patients, folic acid deficiency in 15.66%, and vitamin B12 deficiency in 7.23%. Plasma homocysteine concentrations were inversely correlated with folic acid (r = ,0.27, p = 0.01) and vitamin B12 (r = ,0.21; p = 0.05) concentrations. The individuals with a heterozygous genotype for the G1793A mutation showed borderlines or deficient values in folic acid and vitamin B12 concentrations compared to individuals with a normal genotype. Hyperhomocysteinemia and the vitamin deficiencies presented by type 2 diabetic individuals, included with a heterozygous genotype for the G1793A mutation in the MTHFR gene, reached normal values by daily folic acid supplementation. [source] | ||||||||||