The effect of vitamin B12 inhibition in vivo: impaired folate polyglutamate biosynthesis indicating that 5-methyltetrahydropteroylglutamate is not its usual substrate.
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Biomedical subjects
Publications and source records attributed to J M Scott.
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Further analysis of rat urine containing labelled catabolites derived from administered 3H- or 14C-labelled folic acid is described. The results support previously described studies, and show that folate catabolism in the rat takes place by cleavage of the C9-N10 bond, and not by excretion of inactive forms of the vitamin which still contain the intact folate skeleton.
The results show that the varied appearance of the umbilical cord at birth can be related to its water content and that there are associated changes to be seen histologically in all layers of the cord, but especially in Wharton's jelly. Quantimet analysis confirms these findings and highlights a small group where dual pathology may exist. The relationship between oedematous cords, large drip volume, and respiratory distress in the newborn is considered, and a possible explanation for reduced placental transfusion and low red cell mass in these babies is proffered.
The protective value of double vaccination with 11 recently isolated stabilates of Trypanosoma congolense given either as live or dead organisms, followed by trypanocidal therapy, was assessed in zebu cattle subsequently challenged by nine of the original stabilates. Both vaccination regimens failed to prevent the animals becoming parasitaemic and eventually succumbing to the infection, although the mean survival times and prepatent periods of the calves which received the live vaccine were longer than those of both the groups which had received the dead vaccine and the challenge controls.
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1. The recent suggestions that folate polyglutamate biosynthesis demonstrated in vivo with [3'5'9(n)-3H]folic acid is due to exchange and cannot be achieved with [2(-14)C]folic acid has been demonstrated to be untrue. 2. The compounds formed with both types of radioactive tracer have been shown to be folate polyglutamates from their elution position from precalibrated ion-exchange columns and their susceptibility to hydrolysis by a gamma-carboxypeptidase (conjugase) from human sera. 3. By the use of the methods involving [2(-14)C]folic acid, reported by others to give only folate monoglutamates, we have been able to demonstrate clearly the presence of folate polyglutamates.
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This paper analyzes characteristic patterns of interaction by male homosexuals in the group treatment context according to both psychodynamic and behavioral criteria. Extensive clinical observation has yielded an overview of high probability homosexual response in group settings to the masculine male, older male, feminine male, feminine female, older feminine female, and masculine female. The nature of self-exploration and expression of intimacy is affected deeply by certain key intrapsychic factors and subtle situational cues. The paper stresses the critical importance associated with group leaders acquiring an understanding of antecedents to personality deficits in male homosexuals.
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An investigation of trypanosomiasis in camels indicated a high prevalence of infection in southern Ethiopia. Various direct and indirect laboratory methods for the diagnosis of infection with Trypanosoma evansi were compared and evaluated. At the present time inoculation of camel blood into laboratory rodents appears to be the best direct diagnostic method. The formol-gel test and the Takata test appear to be the most sensitive and accurate of the biochemical methods available. However, there still remains a need for an accurate diagnostic test for individual cases.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
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The synthesis of liver pteroylglutamates (folates) from injected [3-H]-pteroylglutamic acid was investigated in vitamin B-12 methionine-deficient rats and pair-fed controls using improved extraction and chromatographic procedures to identify the monoglutamyl derivatives present. Livers from deficient animals had significantly increased levels of radioactive 5-methyltetrahydropteroylglutamate detected after conjugase treatment of extracts and significantly decreased levels of radioactive tetrahydropteroylglutamate and formylated derivatives. However, that this is only a temporary effect and the result of a decreased rate of equilibration of the exogenous radioactivity was shown by measuring the fully equilibrated endogenous pools. This was done by microbiological assay of the endogenous liver folates with Lactobacillus casei. No significant difference was found between deficient animals and controls in the proportion of the endogenous microbiologically active derivatives present. These results in the rat do not support the idea that in vitamin B-12 deficiency the cellular folates accumulate as the reduced 5-methyl derivative, resulting in inadequate amount of the other cofactors to partipicate in nucleic acid biosynthesis.
A popluation survey covering over a quarter of a century has shown clearly the improvement in haemoglobin levels in women attending antenatal clinics at the Glasgow Royal Maternity Hospital. Various influences have helped to bring this about, foremost among these being routine early prophylaxis with combined iron and folate supplements. Indeed, a time-space relationship between changes in prophylactic therapy, rates of improvement, and the incidence of megaloblastic anaemia can be shown. The women at risk are still essentially the same except for a new group of young, unmarried girls, who must be watched. In our view the withdrawal of routine prophylactic therapy in pregnancy would be retrograde step.