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Biomedical subjects

D M Matthews

Publications and source records attributed to D M Matthews.

At least 127 records · Page 7Linked to original sources
PubMed1971

Cobalamins in human pregnancy and lactation.

Samples of maternal and foetal blood and of human milk, cow's milk, and dried cow's milk have been analysed for cobalamins by chromatography and bioautography. Plasma cobalamins in late pregnancy and after delivery differed quantitatively from those in healthy non-pregnant women. Differences in the proportions of plasma cobalamins were also observed between mothers and their newborn infants. The findings suggest that methylcobalamin may be a more labile plasma form of the vitamin than 5-deoxyadenosyl cobalamin. Breast milk from healthy mothers contained more deoxyadenosylcobalamin and proportionately less methylcobalamin than their plasma. Cyanocobalamin given parenterally to lactating women was detected in the plasma, and high concentrations appeared unchanged in the milk. The B(12) in fresh cow's milk was found to be largely 5-deoxyadenosyl cobalamin whereas dried milk contained only hydroxocobalamin and a little cyanocobalamin. The nutritional implications of the findings, and their bearing on problems of cobalamin transport, are discussed.

Adolescent↗
PubMed1970

Intestinal absorption of two dipeptides in Hartnup disease.

The results of oral tolerance tests of two dipeptides and of their constitutent amino acids are compared in normal subjects and in a case of Hartnup disease. In the control subjects the rate of absorption of phenylalanine from phenylalanyl-phenylalanine and of tryptophan from glycyl-tryptophan was slower than after the equivalent amount of the free amino acids. Absorption of the two essential amino acids (tryptophan and phenylalanine) in the patient was almost zero after administration in the free form, but was much greater after the dipeptide. Results of experiments on absorption and hydrolysis of the two peptides in the rat small intestine are also reported. It is suggested that whereas normal subjects absorb essential amino acids by a dual mechanism of mucosal uptake of free amino acids and oligopeptides, nutrition in Hartnup disease is largely dependent on uptake of oligopeptides containing the amino acids affected by the intestinal transport defect of the disease.

Adult↗
PubMed1969

Patterns of plasma cobalamins in control subjects and in cases of vitamin B12 deficiency.

A method for thin-layer chromatography and bioautography of plasma cobalamins is described. It requires only 5 ml of blood. Results are reported in 35 healthy people and hospital controls, and in 14 cases of untreated pernicious anaemia. In the control group there were two major components, methylcobalamin and a component which is probably a mixture of hydroxocobalamin and deoxyadenosyl cobalamin. Many cases of untreated pernicious anaemia showed a characteristic pattern in which methylcobalamin was reduced in relation to hydroxocobalamin. This pattern was also seen in one vegan who was taking a diet without B(12) supplement. A minority of subjects showed traces of cyanocobalamin; this compound was not confined to smokers. The significance of the results and possible diagnostic utility of the technique are discussed.

Adult↗