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Biomedical subjects

D V Ashley

Publications and source records attributed to D V Ashley.

10 recordsLinked to original sources
PubMed1985

Evidence for diminished brain 5-hydroxytryptamine biosynthesis in obese diabetic and non-diabetic humans.

Obese persons are often reported to have marked cravings for simple carbohydrate-rich foods. Because of the proposed relationships between protein/carbohydrate selection, plasma tryptophan (TRP) to large neutral amino acids (LNAA) ratios, and brain 5-hydroxytryptamine (5-HT) neurotransmission, we examined the plasma TRP/LNAA ratios in four categories of obese subjects, before and 120 min after oral glucose tolerance test (GTT). Plasma TRP/LNAA ratios were reduced in obese, non-diabetics by 18%, the same extent as for older (approximately 52 yr old) nonobese subjects. In more advanced obesity, ie obesity associated either with glucose intolerance, hyperinsulinemia or hypoinsulinemia, plasma TRP/LNAA ratios were reduced by 25%. One hundred twenty minutes after a 100 g glucose load plasma TRP/LNAA had not been normalized. Based on animal data, these results suggest there may be diminished 5-HT neurotransmission in obese diabetics. The implications of these findings for the cravings of obese for carbohydrate-rich foods is discussed.

Adolescent↗
PubMed1979

Effect of mineral mixture in diet on protein intake regulation in the weanling rat.

Weanling rats fed a choice of two diets varying only in protein concentration (10 and 60% casein) select a lower proportion of dietary energy as protein when the dietary minerals are supplied by a mineral mixture high in Na, K, and Cl but low in P and Cu (Hi Cl) than when the diets contain the Bernhart-Tomarelli (BT) mineral mixture. The addition of Na and/or K as acetate salts to the BT mineral mixture, to levels in the Hi Cl mixture, had no effect on regulation of protein intake. However, the addition of Na and/or K as chloride salts to the BT mineral mixture resulted in the rats selecting a protein concentration equivalent to the Hi Cl fed group. Weight gains and energy consumption were similar for all groups. It was therefore concluded that dietary chloride affects protein feeding behavior.

Acetates↗
PubMed1976

Utilization of L-methionine sulfoxide, L-methionine sulfone and cysteic acid by the weanling rat.

Three experiments were conducted to test the ability of weanling rats to utilize the oxidized forms of the sulfur amino acids methionine and cysteine for growth. In the first two experiments, diets were fed which contained graded levels of methionine, methionine sulfoxide and methionine sulfone. The third experiment included a comparison of two dietary levels of cysteine and cysteic acid. The 2 week weight gain and food consumption data indicated that methionine sulfoxide was utilized for growth with only 60% of the efficiency of that achieved by rats fed methionine. Methionine sulfone was not utilized for growth. Analysis of plasma sulfur amino acids showed that the rat has a limited capacity to utilize methionine sulfoxide by effecting its reduction to methionine. Cysteic acid did not support weight gain. This amino acid appeared to be rapidly catabolized to taurine. It was concluded that methionine sulfone and cysteic acid cannot be utilized by the weanling rat. Methionine sulfoxide cannot fully meet the dietary requirement of the rat methionine because of its limited capacity to reduce this amino acid.

Amino Acids↗
PubMed1975

Food intake regulation in the weanling rat: effects of the most limiting essential amino acids of gluten, casein, and zein on the self-selection of protein and energy.

The effects of altering the quality of the dietary protein source on the self-selection of protein and energy by the weanling rat simultaneously offered a choice of two diets differing only in protein concentration were tested. The protein-energy selected was measured when the first limiting amino acid lysine was added to gluten; when lysine, methionine, or the first four limiting amino acids were added to gluten or to casein; or when the nutritional quality of zein was altered by manipulation of the content of tryptophan, lysine, or the four most limiting amino acids. The additions of lysine to gluten caused a decrease in the protein-energy selected and an increase in growth rate of the weanling rat. However, improving the amino acid balance of casein or zein did not have this effect. It was concluded that the selection of protein and energy by weanling rats is not related to the nutritional quality of the protein fed.

Amino Acids, Essential↗
PubMed1975

Correlation between the plasma tryptophan to neutral amino acid ratio and protein intake in the self-selecting weanling rat.

The relationship between changes in blood plasma amino acids and the quantity of protein and energy self-selected by the weanling rat, simultaneously offered two diets varying only in protein concentration, was examined. The changes in the quantity of protein and energy consumed by the rats, which were brought about by the addition of the essential limiting amino acids and groups of essential amino acids to gluten, casein, and zein, were not linearly related to alterations in the total plasma amino acid concentrations or to the accumulation of the added amino acids in the blood plasma. However a consistent relationship between food intake and plasma acids was identified when the plasma tryptophan to neutral amino acid ratio was correlated with the protein intake selected. It is postulated that the ratio of tryptophan to neutral amino acids in the plasma is involved in, or reflects, a mechanism regulating protein intake.

Amino Acids↗