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Biomedical subjects

V Herbert

Publications and source records attributed to V Herbert.

At least 91 records · Page 5Linked to original sources
PubMed1984

Is there a "gold standard" for human serum vitamin B12 assay?

In a study from four laboratories using two commercial vitamin B12 radioassays (impure hog intrinsic factor concentrate containing both intrinsic factor and R binders (IF + R) to measure total corrinoids and the same concentrate presaturated with cobinamide (Cbi) to block B12 binding sites on R binder (IF + R + Cbi) to measure only cobalamins), the rank order of results was generally the same. The concordance between the two tests for classifying sera as normal or deficient was 91% in 311 serum samples. Three percent of sera below the "true B12" (B12 binding to IF + R + Cbi) normal cut-off point were not below the cut-off point for normal "total B12" (B12 binding to IF + R); 6% of sera below the total B12 normal cut-off point were not below true B12 cut-off point. The correlations between Euglena gracilis and the radioassays were 0.80 and 0.83 in the 50 serum samples that also had E. gracilis serum vitamin B12 levels. Lactobacillus leichmannii serum vitamin B12 levels were determined in 49 of the 311 serum samples and results were comparable with results obtained by four radioassay binder systems: IF + R, IF + R + Cbi, highly purified hog IF, and saliva R binder. The closest correlate with L. leichmannii was radioassay using IF + R as binder (r = 0.93), then IF + R + Cbi (r = 0.92), pure IF (r = 0.80), and pure R (r = 0.73). The key to reliable results appears not to reside in a particular assay but rather in determining for each assay its own range of results in participants determined clinically and morphologically normal vs. participants with deficient vitamin B12 (with B12 deficiency defined independently of a serum B12 assay). When laboratory assay results differ from clinical judgment, further evaluation is the appropriate course. There is no "gold standard" for human serum vitamin B12 assay.

Biological Assay↗
PubMed1983

Transcobalamin II deficiency associated with unusual bone marrow findings and chromosomal abnormalities.

A female infant presented at seven weeks of age with failure to thrive, progressively severe pancytopenia, hypogammaglobulinemia and, mucosal ulceration. Bone marrow morphology showed severed megaloblastic changes in the myeloid series with a shift to the left and an increased number of blasts with abnormal morphology. Erythroid precursors and megakaryocytes were markedly decreased. Cytogenetic studies showed marked aneuploidy and increased chromosomal breakage. Treatment with high doses of vitamin B12 resulted in a dramatic clinical response with hematological values becoming normal. The patient's serum showed absence of transcobalamin II, and very little TC I and TC III binding. The patient's parents had only half the lower limits of normal transcobalamin II. QUSO G-32 was used for separation of transcobalamins, and the results were confirmed by Sephacryl S-300. This case illustrates the usefulness of QUSO in the rapid diagnosis of transcobalamin II deficiency.

Blood Cell Count↗
PubMed1983

Noncobalamin vitamin B12 analogues in human red cells, liver, and brain.

Analogues of vitamin B12 which appear to be noncobalamin corrinoids appear to be present in human red cells, liver, and brain. Their sources, nature, and effects require study, particularly with reference to their positive and/or negative effects on vitamin B12 metabolism. In normal persons, they are concentrated in liver, with only small quantities in red cells and still smaller quantities in brain. Their concentrations in disease states will be of interest, particularly in persons with varying degrees of neurological damage associated with deficiencies in vitamin B12 or analogue metabolism.

Adult↗
PubMed1982

Mutagenicity of diisopropylamine dichloroacetate, the "active constituent" of vitamin B15 (pangamic acid).

Diisopropylamine dichloroacetate, the active component of many formulations of pangamic acid (trade-named "vitamin B15"), and diisopropylamine, a component of diisopropylamine dichloroacetate, both demonstrate mutagenicity in the Ames Salmonella/mammalian microsome mutagenicity test. Ninety percent of such agents prove carcinogenic, and this long-term possibility must be considered in any proposed use of pangamic acid containing diisopropylamine or diisopropylamine dichloroacetate.

Calcium Gluconate↗