title: Cytochemical detection of homocysteine in pernicious anemia and in chronic erythremic myelosis.
abstract: Utilizing a unique ability of homocysteine to form a yellow-brown precipitate with nickel chloride, a cytochemical test was developed in an effort to identify this amino acid. Among a variety of types of anemias studied, bright yellow-colored erythrocytes and erythroid precursors were found only in marrows from patients who had untreated pernicious anemia and chronic erythremic myelosis. The results of the study support the "methyltetrahydrofolate-trap" hypothesis in vitamin B12 deficiency, in which decreased activity of the methylocobalamin-dependent methyltransferase enzyme is believed to lead to accumulation of methyltetrahydrofolate and homocysteine in the deficient cells. The findings also raise the possibility that similar intracellular accumulations of homocysteine may occur in chronic erythremic myelosis, perhaps as a result of  a defect in the methyltransferase enzyme.
mesh_terms: D013766:5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase / Q000378:metabolism; D000752:Anemia, Pernicious / Q000378:metabolism*; D001853:Bone Marrow / Q000378:metabolism; D001854:Bone Marrow Cells; D004912:Erythrocytes / Q000378:metabolism; D006651:Histocytochemistry; D006710:Homocysteine / Q000378:metabolism*; D006801:Humans; D004915:Leukemia, Erythroblastic, Acute / Q000097:blood / Q000378:metabolism*; D009532:Nickel; D014806:Vitamin B 12 Deficiency / Q000378:metabolism
chemical_list: D006710:Homocysteine; D009532:Nickel; D013766:5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase