Biomaterial Database

A microbiologic disc assay for 5-methyltetrahydrofolate in the presence of methotrexate. 1977

B M Mehta, and D J Hutchison

High-dose methotrexate-citrovorum factor rescue regimens are used extensively for the treatment of human malignancies. Since the rescue agent citrovorum factor is rapidly converted to 5-methyltetrahydrofolate, it is desirable to follow the distribution kinetics of both of these coenzymes to assess the selective therapeutic effectiveness of the regimen. The assay methods using methotrexate-resistant strains of Lactobacillus casei ATCC 7469 (LC/A), Streptococcus faecium var. durans ATCC 8043 (SF/A), and Pediococcus cerevisiae ATCC 8081 (PC/A) have been developed to determine the concentrations of 5-methyltetrahydrofolate and other folates in the presence of methotrexate. Since LC/A determines the total folates, SF/A deterimines the total folates except 5-methyltetrahydrofolate, and PC/A by our procedure determines only the most stable form of reduced folates, citrovorum factor, the quantitation of both 5-methyltetrahydrofolate and citrovorum factor can very easily be achieved by differential assays. This report describes the determination of as low as 10 ng/ml of 5-methyltetrahydrofolate in the presence of as high as 500 microgram/ml of methotrexate. The assay method described here is currently used in studying the pharmacokinetics of 5-methyltetrahydrofolate in patients with meningeal neoplasms.

UI	MeSH Term	Description	Entries
D007780	Lacticaseibacillus casei	A rod-shaped bacterium isolated from milk and cheese, dairy products and dairy environments, sour dough, cow dung, silage, and human mouth, human intestinal contents and stools, and the human vagina. L. casei is CATALASE positive.	Lactobacillus casei
D008727	Methotrexate	An antineoplastic antimetabolite with immunosuppressant properties. It is an inhibitor of TETRAHYDROFOLATE DEHYDROGENASE and prevents the formation of tetrahydrofolate, necessary for synthesis of thymidylate, an essential component of DNA.	Amethopterin,Methotrexate Hydrate,Methotrexate Sodium,Methotrexate, (D)-Isomer,Methotrexate, (DL)-Isomer,Methotrexate, Dicesium Salt,Methotrexate, Disodium Salt,Methotrexate, Sodium Salt,Mexate,Dicesium Salt Methotrexate,Hydrate, Methotrexate,Sodium, Methotrexate
D010376	Pediococcus	A genus of gram-positive, facultatively anaerobic bacteria whose growth is dependent on the presence of a fermentable carbohydrate. No endospores are produced. Its organisms are found in fermenting plant products and are nonpathogenic to plants and animals, including humans.
D002955	Leucovorin	The active metabolite of FOLIC ACID. Leucovorin is used principally as an antidote to FOLIC ACID ANTAGONISTS.	Calcium Leucovorin,Citrovorum Factor,Folinic Acid,N(5)-Formyltetrahydrofolate,5-Formyltetrahydrofolate,5-Formyltetrahydropteroylglutamate,Calcium Folinate,Folinic Acid-SF,Leucovorin, (D)-Isomer,Leucovorin, (DL)-Isomer,Leucovorin, (R)-Isomer,Leucovorin, Calcium (1:1) Salt,Leucovorin, Calcium (1:1) Salt, (DL)-Isomer,Leucovorin, Calcium (1:1) Salt, Pentahydrate,Leucovorin, Monosodium Salt,Leukovorin,Leukovorum,Wellcovorin,5 Formyltetrahydrofolate,5 Formyltetrahydropteroylglutamate,Acid, Folinic,Factor, Citrovorum,Folinate, Calcium,Folinic Acid SF,Leucovorin, Calcium,Monosodium Salt Leucovorin
D001681	Biological Assay	A method of measuring the effects of a biologically active substance using an intermediate in vivo or in vitro tissue or cell model under controlled conditions. It includes virulence studies in animal fetuses in utero, mouse convulsion bioassay of insulin, quantitation of tumor-initiator systems in mouse skin, calculation of potentiating effects of a hormonal factor in an isolated strip of contracting stomach muscle, etc.	Bioassay,Assay, Biological,Assays, Biological,Biologic Assay,Biologic Assays,Assay, Biologic,Assays, Biologic,Bioassays,Biological Assays
D013291	Streptococcus	A genus of gram-positive, coccoid bacteria whose organisms occur in pairs or chains. No endospores are produced. Many species exist as commensals or parasites on man or animals with some being highly pathogenic. A few species are saprophytes and occur in the natural environment.
D013763	Tetrahydrofolates	Compounds based on 5,6,7,8-tetrahydrofolate.

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