Proceedings: Dietary folates and their availability to man.
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Diet↗
Biomedical subjects
R J Leeming
Publications and source records attributed to R J Leeming.
Folates in human serum.
Constituent serum folates have been shown to be altered and in some cases raised in diseases in which total folate levels are known to be frequently decreased. Absorption experiments showed that orally administered folate analogues affect the folate pool in different ways. The stability of the 10-formyltetrahydrofolate level in normal subjects is demonstrated.
Administration, Oral↗
Proceedings: Intestinal absorption of tetrahydrobiopterin and pterolic acid in man: a comparison of models for the transport of folates across the small intestine.
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Folic Acid↗
An automated method for microbiological assays.
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Autoanalysis↗
The occurrence of folic acid (pteroyl-L-monoglutamic acid) in human blood serum after small oral doses.
Human serum folates analysed by bioautography after oral doses of 0.5 mg folic acid (pteroyl-L-monoglutamic acid) show folic acid to be present.
Administration, Oral↗
Site of reduction and methylation of folic acid in man.
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Administration, Oral↗
The application of tetrazolium bioautography to the identification of folic acid derivatives.
Tetrazolium bioautography has been applied to the identification of folates in solutions of known concentration, and satisfactory resolution has been obtained between pteroyl-L-monoglutamic acid, calcium leucovorin, and N-5-methyltetrahydrofolic acid. The technique is suitable for the identification of folates in biological solutions, and is more specific than differential microbiological assay.
Acetates↗
T-strain mycoplasma in non-gonococcal urethritis. Pathogen or commensal?
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Female↗
Depression and tetrahydrobiopterin: the folate connection.
Total biopterin, neopterin and creatinine were measured in spot urine samples from affective disorder patients on lithium therapy and control subjects. Folic acid was also measured in plasma in a sample of the patients. The mean neopterin: biopterin ratio was significantly higher in the 76 patients (3.2 +/- 0.5) than in the 61 controls (1.8 +/- 0.1). In female patients biopterin levels were significantly lower than in controls. In the control groups there was a significant correlation between the molar concentration of neopterin and biopterin. No such correlation was found in the patients. These data indicate that tetrahydrobiopterin (BH4) biosynthesis is reduced in this group. A significant positive correlation was found between plasma folate and urinary biopterin. It is suggested that folate deficiency may impair the synthesis of BH4, a cofactor essential for the synthesis of 5-HT and other monoamines that are involved in the pathogenesis of affective disorders.
Adult↗
[Hyperphenylalaninaemia with normal phenylalanine-hydroxylase activity and a deficiency of tetrahydrobiopterin and dihydropteridine reductase].
Two cases of hyperphenylalaninemia with a normal activity of phenylalanine hydroxylase are described. No activity of DHP reductase was found in the first case, having very high biopterin levels in basal conditions and after intravenous perfusion of phenylalanine. In the other case, the DHP reductase activity is normal but plasma and urinary levels of the reduced forms of biopterin are largely lowered and do not increase during the phenylalanine load. Early substitutive treatment with L-dopa and 5-HTP in one of the cases avoided the development of the "progressive neurological illness unresponsive to dietary treatment" characterizing two variants. This raises the question of a liver biopsy in order to assay the hydroxylation enzyme activities when screening hyperphenylalaninemia whatever the type.
Biopterins↗