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Background: Thrombophilia is characterised by an abnormality of blood coagulation that increases thrombosis. Homocystinuria encompasses a group of disorders marked by increased levels of homocysteine and other amino acids detectable in the bloodstream and urine. Conversely, homocystinuria due to methylenetetrahydrofolatereductase (MTHFR) deficiency, a rarer disorder, stems from impaired folate metabolism due to deficient MTHFR enzyme. Case presentation: A 16-year-old boy presented with walking difficulties, headaches, and thrombotic events, thrombophilia workup led to a diagnosis of homocystinuria due to a novel mutation in MTHFR gene. Anticoagulant therapy was initiated which showed clinical improvement, but financial constraints hindered follow-up. Conclusions: This case highlights the complexities of diagnosing and treating paediatric thrombophilia, particularly in resource-limited settings. Notably, the identified homozygous autosomal recessive (AR) missense variation in the MTHFR gene (Exon 4—c582C>G) represents a novel mutation, suggesting the ongoing significance of genetic research in elucidating the underlying mechanisms of thrombotic disorders. [ABSTRACT FROM AUTHOR]

The sources of bioavailable vitamin B12 are limited, and most of them are animal-derived. Chlorella vulgaris, a freshwater microalga, is known for immune system boosting, nutraceutical properties and presence of a natural form of vitamin B12. The present study focused on the in vivo evaluation of the Chlorella biomass as a source of bioavailable vitamin B12 to alleviate the vitamin B12 deficiency status of Wistar rats. Experimental animals were evaluated for the vitamin B12 deficiency-related circulatory marker (serum vitamin B12) and functional markers (plasma homocysteine and urinary methylmalonic acid), haematological and histological changes. The results showed that an increase of 2.4-fold in urinary methylmalonic acid (13.01 ± 0.89 µmoles moles of creatinine−1), 2.6-fold in plasma homocysteine (17.18 ± 3.57 µmole L−1), and 48% decrease in serum vitamin B12 levels (252.69 ± 1.46 pg mL−1) in vitamin B12 deficient group compared to control animals. The Chlorella biomass supplementation in the diet led to the restoration of the functional and circulatory markers, hematological parameters, and vitamin B12 content of kidney and liver to control levels. The Chlorella biomass supplementation increased the erythrocyte precursors and MAST cells in the bone marrow and also normalized the histological features of kidney, liver, and lung tissues. The results suggest that the vitamin B12 from the Chlorella biomass was bioavailable and facilitated the improvement of vitamin B12 status in deficient rats. [ABSTRACT FROM AUTHOR]

Inorganic arsenic (iAs) is an established environmental diabetogen. The link between iAs exposure and diabetes is supported by evidence from adult human cohorts and adult laboratory animals. The contribution of prenatal iAs exposure to the development of diabetes and underlying mechanisms are understudied. The role of factors that modulate iAs metabolism and toxicity in adults and their potential to influence diabetogenic effects of prenatal iAs exposure are also unclear. The goal of this study was to determine if prenatal exposure to iAs impairs glucose metabolism in mice and if maternal supplementation with folate and methylcobalamin (B12) can modify this outcome. C57BL/6J dams were exposed to iAs in drinking water (0, 100, and 1000 µg As/L) and fed a folate/B12 adequate or supplemented diet from before mating to birth of offspring. After birth, dams and offspring drank deionized water and were fed the folate/B12 adequate diet. The metabolic phenotype of offspring was assessed over the course of 14 weeks. Male offspring from iAs-exposed dams fed the folate/B12-adequate diet developed fasting hyperglycemia and insulin resistance. Maternal folate/B12 supplementation rescued this phenotype but had only marginal effects on iAs metabolism in dams. The diabetogenic effects of prenatal iAs exposure in male offspring were not associated with changes in global DNA methylation in the liver. Only minimal effects of prenatal iAs exposure or maternal supplementation were observed in female offspring. These results suggest that prenatal iAs exposure impairs glucose metabolism in a sex-specific manner and that maternal folate/B12 supplementation may improve the metabolic phenotype in offspring. Further studies are needed to identify the mechanisms underlying these effects. [ABSTRACT FROM AUTHOR]

Objectives: Studies have produced conflicting results assessing hyperhomocysteinemia (HYH) treatment with B vitamins in patients with normal cognition, Alzheimer's disease and related disorders (ADRD). This study examined the effect of HYH management with L-methylfolate (LMF), methylcobalamin (MeCbl; B12), and N-acetyl-cysteine (CFLN: Cerefolin®/Cerefolin-NAC®) on cognitive decline. Design: Prospective, case-control study of subjects followed longitudinally. Setting: Outpatient clinic for cognitive disorders. Participants: 116 ADRD patients (34 with HYH, 82 with No-HYH) met inclusion and exclusion criteria to participate. No study participant took B vitamins. Intervention: HYH patients received CFLN, and No-HYH patients did not. Measurements: Cognitive outcome measures included MCI Screen (memory), CERAD Drawings (constructional praxis), Ishihara Number Naming (object recognition), Trails A and B (executive function), and F-A-S test (verbal fluency). Dependent or predictor measures included demographics, functional severity, CFLN and no CFLN treatment duration, ADRD diagnosis, memantine and cholinesterase inhibitor treatment. Linear mixed effects models with covariate adjustment were used to evaluate rate of change on cognitive outcomes. Results: The duration of CFLN treatment, compared to an equivalent duration without CFLN treatment, significantly slowed decline in learning and memory, constructional praxis, and visual-spatial executive function (Trails B). CFLN treatment slowed cognitive decline significantly more for patients with milder baseline severity. CFLN treatment effect increased as baseline functional severity decreased. The analytical model showed that treatment duration must exceed some minimum period of at least one year to slow the rate of cognitive decline. Conclusion: After covariate adjustment, HYH+CFLN significantly slowed cognitive decline compared to No-HYH+No-CFLN. Longer CFLN treatment duration, milder baseline severity, and magnitude of homocysteine reduction from baseline were all significant predictors. There are a number of factors that could account for disagreement with other clinical trials of B vitamin treatment of HYH. Moreover, CFLN is chemically distinct from commonly used B vitamins as both LMF and MeCbl are the fully reduced and bioactive functional forms; CLFN also contains the glutathione precursor, N-acetyl-cysteine. The findings of other B vitamin trials of HYH can, therefore, only partly account for treatment effects of CFLN. These findings warrant further evaluation with a randomized, placebo-controlled trial. [ABSTRACT FROM AUTHOR]

In the environment, the methylation of metal(loid)s is a widespread phenomenon, which enhances both biomobility as well as mostly the toxicity of the precursory metal(loid)s. Different reaction mechanisms have been proposed for arsenic, but not really proven yet. Here, carbon isotope analysis can foster our understanding of these processes, as the extent of the isotopic fractionation allows to differentiate between different types of reaction, such as concerted (S2) or stepwise nucleophilic substitution (S1) as well as to determine the origin of the methyl group. However, for the determination of the kinetic isotope effect the initial isotopic value of the transferred methyl group has to be determined. To that end, we used hydroiodic acid for abstraction of the methyl group from methylcobalamin (CHCob) or S-adenosyl methionine (SAM) and subsequent analysis of the formed methyl iodide by gas chromatography (GC) isotope ratio mass spectrometry (IRMS). In addition, three further independent methods have been investigated to determine the position-specific δC value of CHCob involving photolytic cleavage with different additives or thermolytic cleavage of the methyl-cobalt bonding and subsequent measurement of the formed methane by GC-IRMS. The thermolytic cleavage gave comparable results as the abstraction using HI. In contrast, photolysis led to an isotopic fractionation of about 7 to 9 ‰. Furthermore, we extended a recently developed method for the determination of carbon isotope ratios of organometal(loid)s in complex matrices using hydride generation for volatilization and matrix separation before heart-cut GC and IRMS to the analysis of the low boiling partly methylated arsenicals, which are formed in the course of arsenic methylation. Finally, we demonstrated the applicability of this methodology by investigation of carbon fractionation due to the methyl transfer from CHCob to arsenic induced by glutathione. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Unlabelled: Cobalamin C (Cbl-C) defect is the most common inborn error of cobalamin metabolism which causes a block in the pathway responsible for the synthesis of its two metabolically active forms methyl- and adenosylcobalamin. Cbl-C defect causes the accumulation of methylmalonic acid and homocysteine and decreased methionine synthesis. The clinical presentation of patients with early-onset Cbl-C defect, characterized by a multisystem disease with severe neurological, ocular, hematological, renal, gastrointestinal, cardiac, and pulmonary manifestations, differs considerably from what observed in the "classical" form of methylmalonic aciduria caused by defect of methylmalonyl-CoA mutase. This last condition is in most cases dominated in the neonatal period by a metabolic encephalopathy "intoxication type" with severe hyperammonemia and ketoacidosis. We report a Cbl-C defect patient presenting a neonatal encephalopathy with severe hyperammonemia and ketoacidosis who was successfully treated with peritoneal dialysis.Conclusion: To the best of our knowledge, there are no reported cases of Cbl-C defect showing an acute presentation resembling a classical methylmalonic aciduria. This observation enlarges the spectrum of inherited diseases to be considered in the differential diagnosis of neonatal hyperammonemia. [ABSTRACT FROM AUTHOR]

Objective: To compare the efficacy, safety, and tolerability of Epalrestat with Methylcobalamine in patients with diabetic neuropathy.Materials and Methods: This prospective, open-labeled, comparative, and multicentric study was conducted on an outpatient basis by qualified investigators at four different centers. A total of 242 patients with diabetic neuropathy were enrolled in the study. The enrollment of patients was as per inclusion/exclusion criteria. After obtaining their informed consent, they were individually interviewed, examined, investigated, and treated as per the study protocol. Each patient was administered with one tablet containing Epalrestat 50 mg thrice daily or Methylcobalamine 500 microg thrice daily for 12 weeks. They were followed up at the end of weeks 4, 8, and 12 for their examination. Therapeutic success was assessed in terms of clinical symptoms, physical examinations, and electrophysiological assessments.Results: A significant improvement in all the efficacy parameters was observed with Epalrestat treatment compared to Methylcobalamin treatment. The efficacy parameters assessed were loss of sensation, burning sensation, numbness, muscle cramps, spontaneous pain, weakness, mean score of isometric muscle strength, tendon reflexes, and sensation. Epalrestat treatment is associated with very few adverse events. The tolerability to Epalrestat treatment was also reported to be excellent in the majority of the study population compared to tolerability to Methylcobalamine. Patients as well as physicians reported that the Epalrestat treatment is superior in efficacy and safety parameters compared to Methylcobalamin.Conclusion: The present study concludes that Epalrestat has better efficacy and safety profile than Methylcobalamine in the treatment of diabetic neuropathy. [ABSTRACT FROM AUTHOR]

Homocysteine is a predictor of vascular disease and may have an important role in diabetes. In this study, we examined the effects of folic acid and methylcobalamin supplementation on changes in homocysteine (Hcy) levels and homocysteine thiolactonase/paraoxonase (HTase/PON) activity in a short-term trial. Ninety patients with type 2 diabetes were randomly divided into three groups: Group I received no vitamin supplementation, group II received 5 mg/day folic acid (orally), group III received folic acid (5 mg/day) in combination with methylcobalamin (500 μg/day; intramuscularly, on prescription). All patients were treated for 2 weeks. Plasma Hcy, HTase/PON activity, vitamin B12, and folic acid were measured before and after supplementation in each group. In addition, forty healthy (nondiabetic) controls were enrolled. Serum HTase/PON activity was significantly higher in diabetics compared with controls, plasma Hcy levels were significantly lower ( P<0.05). After vitamin supplementation there was a significant reduction in plasma Hcy levels. The mean percentage reduction in Hcy was 2.75% in group I, 14% in group II and 37.3% in group III. There was a significant inverse correlation between the changes in HTase/PON activity and Hcy levels ( r=−0.29, P=0.004). A 2.72% increase in HTase/PON activity was seen in group I, an 8.03% increase was detected when folic acid was given in group II ( P<0.001), and a 17.59% increase in HTase/PON activity was seen in group III ( P<0.001). Short-term oral folic acid (5 mg/day) supplementation with or without methylcobalamin appeared to be an effective approach to decrease Hcy levels and increase HTase/PON activity in patients with type 2 diabetes. A decrease in plasma Hcy levels may partly account for the elevation of serum HTase/PON activity. This could be a novel mechanism to protect against vascular diabetic complications. [ABSTRACT FROM AUTHOR]

The enzyme N -methyltetrahydrofolate: homocysteine methyltransferase (methionine synthetase) catalyzes the synthesis of methionine from homocysteine. Methylcobalamin is a cofactor for the reaction. The effects of methionine deprivation and methylcobalamin supplementation on the growth of normal and transformed rat liver epithelial cell lines were determined using growth constants to quantitate cell proliferation. No marked specific requirement by the transformed cell lines for methionine relative to leucine was observed. A sigmoidal relationship, however, was found to exist between growth constants and the logarithms of the amino acid concentrations for both normal and transformed cells. Methylcobalamin stimulated the growth rates of the normal and transformed liver cells in methionine-deficient, homocysteine-containing medium. Growth on methionine was not increased by the addition of methylcobalamin. The growth constants for two normal, two spontaneously transformed, one chemically transformed, and one tumor cell line grown in medium in which methionine was replaced by homocysteine were found to be proportional to the level of methionine synthetase. The results demonstrate the utility of growth quantitation to study the methionine dependency of transformed cells. [ABSTRACT FROM AUTHOR]

In this study, cobalamin deficiency was produced in vitro by the use of nitrous oxide, known to inactivate the vitamin. In 14 sets of experiments, normal human lymphocytes stimulated with phytohemagglutinin on day 0 were exposed to nitrous oxide and oxygen on day 2. McCbl was delivered later to half of the cells. Untreated cells served as a control. On day 3, the cells were harvested, the lymphocytes were lysed, and the obtained extracts were assayed for thymidylate synthetase. In 16 other experiments the same procedure was performed, and the incorporation of radioactive thymidine or deoxyuridine by the intact cells was measured. In additional experiments, a deoxyuridine suppression test of treated and untreated stimulated lymphocytes was also performed. The results indicate that nitrous oxide significantly reduces the activity of thymidylate synthetase and that this reduction is significantly corrected by McCbl, suggesting a causative relation between the vitamin and the enzyme. However, there was no statistically significant effect of nitrous oxide demonstrated on the nucleoside incorporation nor on the deoxyuridine suppression test. [ABSTRACT FROM AUTHOR]

In this study, the effects of methylcobalamin on testicular damage induced by ethylene oxide (EtO) were studied. When Wistar male rats inhaled EtO at 500 ppm, 6 h a day, 3 days a week, for 6 weeks, testicular damage was observed histopathologically and by some other parameters. Subcutaneous injection of methylcobalamin at 500 μg/kg, 5 times/week was found to ameliorate the damage. However, the degree of the methylcobalamin effect differed among the parameters examined in this study. Decrease in testicular weight due to EtO exposure was completely prevented by methylcobalamin, and decrease in testicular mature spermatid count and LDH-X activity was fairly well prevented. The degree of prevention of alteration in the epididymis, such as epididymal weight, epididymal sperm count and sperm abnormality rate, was significant but not complete. EtO caused apparent alterations in glutathione metabolism in the testes, but methylcobalamin did not affect such alterations induced by EtO. From these results, it has been determined that methylcobalamin has definite preventive effects on testicular toxicity of EtO. [ABSTRACT FROM AUTHOR]

Novel vitamin B analogues in which the D-ribose moiety of the nucleotide loop was replaced by an oligomethylene group and a trimethylene analogue containing imidazole instead of 5,6-dimethylbenzimidazole as well as cobinamide methyl phosphate were tested for biological activities with Escherichia coli 215, a B- or methionine-auxotroph, and Lactobacillus leichmannii ATCC 7830 as test organisms. A cyano form of 5,6-dimethylbenzimidazolyl tetramethylene, trimethylene and hexamethylene analogues supported the growth of L. leichmannii in this order. 5.6-Dimethylbenzimidazolyl dimethylene and imidazolyl trimethylene analogues did not show B activity and behaved as weak B antagonists when added together with cyanocobalamin. An adenosyl form of the biologically active analogues served as coenzymes for ribonucleotide reductase of this bacterium, whereas that of the inactive analogues did not. The latter acted as weak competitive inhibitors against adenosylcobalamin. ON the contrary, all the analogues did not support the growth of E. coli 215 at all by themselves and inhibited the growth when added with a suboptimum level of cyanocobalamin. A methyl form of the analogues also did not support the growth of E. coli 215, although they served as active coenzymes for methionine synthase of the bacterium. Since unlabeled analogues strongly inhibited the uptake of [H]cyanocobalamin by this bacterium, it seems likely that the analogues exert their anti-B activity toward E. coli 215 by blocking the B-transport system [ABSTRACT FROM AUTHOR]

Methanosarcina barkeri was recently shown to contain two cytoplasmic isoenzymes of methylcobalamin: coenzyme M methyltransferase (methyltransferase 2). Isoenzyme I predominated in methanol-grown cells and isoenzyme II in acetate-grown cells. It was therefore suggested that isoenzyme I functions in methanogenesis from methanol and isoenzyme II in methanogenesis from acetate. We report here that cells of M. barkeri grown on trimethylamine, H/CO, or acetate contain mainly isoenzyme II. These cells were found to have in common that they can catalyze the formation of methane from trimethylamine and H, whereas only acetate-grown cells can mediate the formation of methane from acetate. Methanol-grown cells, which contained only low concentrations of isoenzyme II, were unable to mediate the formation of methane from both trimethylamine and acetate. These and other results suggest that isoenzyme II (i) is employed for methane formation from trimethylamine rather than from acetate, (ii) is constitutively expressed rather than trimethylamine-induced, and (iii) is repressed by methanol. The constitutive expression of isoenzyme II in acetate-grown M. barkeri can explain its presence in these cells. The N-terminal amino acid sequences of isoenzyme I and isoenzyme II were analyzed and found to be only 55% similar. [ABSTRACT FROM AUTHOR]

A vitamin B requiring strain was isolated from Chlostridium cochlearium T-2 C which is known to synthesize various types of vitamin B including methylcobalamin and has an ability to methylate inorganic mercury. The vitamin B auxotroph lacking the mercury-methylating activity showed higher sensitivity to inorganic mercury than its original strain, while the sensitivity of both strains to methylmercury was relatively low and essentially the same. These data seem to present affirmative evidence to postulate the physiological role of methylcobalamin-dependent methylation of mercury to be a process of detoxication. [ABSTRACT FROM AUTHOR]