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At least 523 records · Page 29Linked to original sources
PubMed1994

Nitritocobalamin and nitrosocobalamin may be confused with sulfitocobalamin using cation-exchange chromatography.

The previously reported ability of SP-Sephadex C25 column chromatography for partitioning biologically important cobalamins has been modified to include analytical separation of nitritocobalamin (NO2-Cbl) and nitrosocobalamin (NO-Cbl). Gel column dimensions (1.5 x 11.0 cm), a low eluent flow-rate (125 microliters/min), collection of small eluate fractions (160 microliters) plus maintenance of He saturated mobile and gel phases all combined to eliminate ordinarily confusing proximal elution of NO2-Cbl and NO-Cb1 with sulfitocobalamin (SO3-Cbl) and cyanocobalamin. Cobalamin elution profiles from the gel column were monitored by direct radiometric analysis of 57Co-labelled cobalamin standards or competitive intrinsic factor radioassays for cobalamin sample sizes up to 10.0 ng. Failure to implement the chromatographic conditions detailed here totally obscured analysis of NO2-Cbl coexisting with SO3-Cbl in brain tissues for chicks exposed to dietary sulfites and caused oversight of NO-Cb1 normally coexisting in prepared NO2-Cbl standards.

Animals↗
PubMed1987

Hydroxycobalamin/sodium thiosulfate as a cyanide antidote.

Severe, acute cyanide poisoning is uncommon and can be very difficult to diagnose if a history of exposure is unavailable. Victims of smoke inhalation may have significant cyanide poisoning as well as carbon monoxide toxicity. The Lilly Cyanide Antidote Kit currently available in America unfortunately has its own inherent toxicity. An efficacious antidote lacking toxicity is desirable, especially in cases where the diagnosis of cyanide poisoning cannot be made with certainty. Hydroxycobalamin/sodium thiosulfate has been used in France since 1970. Both components have been shown to be safe and efficacious in animal studies. Case reports of human cyanide poisoning treated with hydroxycobalamin/sodium thiosulfate have been published only in French. Animal and human data on the use of this antidotal combination are reviewed. Hydroxycobalamin/sodium thiosulfate is an efficacious cyanide antidote with little inherent toxicity.

Acute Disease↗
PubMedDate not supplied

Cyanide poisoning from propionitrile exposure.

A 55-year-old worker was exposed to propionitrile by both the inhalational and dermal routes. He rapidly lost consciousness and developed metabolic acidosis consistent with cyanide poisoning. Treatment with hydroxycobalamin and sodium thiosulfate produced complete symptom resolution within an hour. Serial blood cyanide and thiocyanate levels documented a rapid decrease in cyanide and concomitant increase in thiocyanate. Serious cyanide poisoning can occur from propionitrile exposure. Treatment with hydroxycobalamin and sodium thiosulfate can produce rapid clinical improvement.

Cyanides↗
PubMed2005

Prenatal and postnatal treatment in cobalamin C defect.

OBJECTIVE: To evaluate prenatal treatment with hydroxycobalamin (OH-Cbl) in a pregnancy at risk for a severe form of the cobalamin C defect and postnatal treatment of the affected child. STUDY DESIGN: Observational study with non-randomized intervention. RESULTS: In contrast to reported pregnancies with affected fetuses in which maternal methylmalonic aciduria was found in the last trimester of pregnancy, there was no maternal methylmalonic aciduria in our case, given prenatal treatment with intramuscular OH-Cbl. We did not find that the concentration of odd long-chain fatty acids in cord blood erythrocytes reflects fetal methylmalonic academia. After birth, the infant was treated with intramuscular OH-Cbl and oral carnitine. Oral folate and betaine were added as adjunct therapy to decrease plasma total homocysteine. Because of inadequate metabolic control, a diet reduced in natural protein was introduced. The child had normal developmental milestones but had nystagmus, hyperpigmented retinopathy, and discrete truncal muscular hypotonia. CONCLUSIONS: Despite prenatal and postnatal treatment, adequate metabolic control, absence of metabolic crises, and normal developmental milestones, this patient with the cobalamin C defect had characteristic symptoms of the disease.

Betaine↗
PubMed2005

New developments in antidotes.

Although some antidotes are rarely used, they have an important, potentially life-saving role in the treatment of toxic exposures. The timely and judicious use of an antidote can prevent death and shorten hospitalization as well as reduce the patient's pain and suffering. Although their importance is recognized, sufficient stocking of antidotes remains a problem.

Animals↗
PubMed2006

Subacute combined degeneration of the spinal cord in cblC disorder despite treatment with B12.

Subacute combined degeneration (SCD) of the spinal cord is a characteristic complication of vitamin B12 deficiency, but it has never been neuropathologically demonstrated in a B12-inborn error of metabolism. In this report SCD is documented in a 15-year-old boy with early-onset cobalamin C (cblC) disorder. The neuropathologic findings included multifocal demyelination and vacuolation with predilection for the dorsal and lateral columns at the mid-thoracic level of the spinal cord, confirming the similarity of SCD in cblC disorder to the classic adult SCD due to vitamin B12 deficiency. SCD developed in this boy despite treatment for cblC disorder that began at 3 months of age. There is clinical and experimental evidence to suggest that a deficiency in remethylation with concomitant reduction in brain methionine may be the cause of SCD. In this patient plasma methionine levels were low without betaine and/or l-methionine supplementation and in the normal range for only a 2-year period during compliance with therapy. In cblC disorder, a consistent increase in blood methionine to high normal or above normal levels by the use of betaine and l-methionine supplementation may be helpful in preventing SCD. This is especially important now that the presymptomatic detection of cblC disorder is possible through the expansion of newborn screening.

Adolescent↗
PubMed1998

Regulation of methionine adenosyltransferase catalytic activity and messenger RNA in SH-SY5Y human neuroblastoma cells.

The human neuroblastoma cell line SH-SY5Y was used to study the regulation of methionine adenosyltransferase (MAT II; E.C.2.5.1.6.) catalytic activity and transcript levels in cells of neuronal origin. The cells were exposed for 24 hr to a medium containing different concentrations of methionine (MAT substrate) as well as medium deficient of methionine. Furthermore, cells were treated with hydroxycobalamin, SAM, and the competitive MAT inhibitor cycloleucine. The MAT catalytic activity was inversely correlated to methionine concentrations, e.g. MAT Vmax increased 2-fold in cells grown in methionine-deficient medium as compared with cells cultured under standard conditions. Interestingly, MAT Km also increased from 9.04 +/- 0.44 to 12.08 +/- 0.83 in the methionine-deficient medium. Hydroxycobalamin caused an increase in activity at 40 microM while a decrease was observed at higher concentrations (100, 200, and 400 microM). Cycloleucine caused a significant inhibition of MAT catalytic activity, i.e. the inhibition was approximately 50% in the presence of 4 mM cycloleucine. The relevance of these results for the understanding of observations on MAT catalytic activity in brains of patients with Alzheimer's disease is discussed.

Alzheimer Disease↗
PubMed1986

Clinical heterogeneity in cobalamin C variant of combined homocystinuria and methylmalonic aciduria.

We describe two patients with methylmalonic aciduria and homocystinuria (Cbl C). The disorder was not diagnosed in patient 1 until 4 1/2 years of age; he had a history of fatigue, anorexia, delirium, and spasticity. Moderate megaloblastic bone marrow changes were observed, and there was hyperreflexia of the lower limbs. His condition improved clinically with hydroxycobalamin therapy. Patient 2 was hospitalized at 6 weeks of age because of lethargy and poor feeding. She was found to have macrocytosis. Despite an initial good clinical response to hydroxycobalamin, she developed a striking pigmentary retinopathy. Methylmalonic aciduria persisted in both patients, and homocystinuria persisted in patient 1 despite therapy. The diagnosis of Cbl C disease has been confirmed in both patients by biochemical studies of cultured fibroblasts, including complementation studies. The differences in age of onset and clinical findings together with the similar biochemical findings in these two patients demonstrate the heterogeneity of phenotypic expression in patients with apparently identical abnormalities of vitamin B12 metabolism.

Amino Acid Metabolism, Inborn Errors↗