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Biomedical subjects

D H Calloway

Publications and source records attributed to D H Calloway.

At least 55 records · Page 3Linked to original sources
PubMed1976

Nitrogen retention in men fed isolated soybean protein supplemented with L-methionine, D-methionine, N-acetyl-L-methionine, or inorganic sulfate.

The ability of various sulfur-containing compounds to replace L-methionine (L-Met) was investigated by metabolic balance studies in man. N-acetyl-L-Methionine (AcMet), D-methionine (D-Met), and sodium sulfate (Na2SO4) were used to supplement a diet deficient in sulfur amino acids. The daily diet contained 4.5 g nitrogen (N) from isolated soybean protein (SB) and 4.5 g from glycine and alanine (9 g total N). SB diet was given alone or supplemented to six adult men for periods of 9 days after a standardization period with an equal N eggwhite diet, preceded by a 2-day zero N adaptation period. Supplements provided equivalent amounts of sulfur to that present in 420 ml L-Met, the amount added to SB to bring the total sulfur amino acid content to 900 mg/day. AcMet was as benfeficial as L-Met in improving N balance but D-Met was not as effective as L-Met. Difference between balances obtained with L-Met and Na2SO4 was not significant due to large variation in response to Na2SO4. While addition of D-Met to SB did not result in significantly greater N retention than unsupplemented SB, NA2SO4 addition did cause increased N retention.

Adult↗
PubMed1976

Basal metabolic rate and work energy expenditure of mature, pregnant women.

Resting and working metabolic rates and physical fitness of twenty-one mature women were studied at various intervals during the last half of pregnance and in sixteen of them again eight to twelve weeks postpartum. Basal rate (BMR) was increased more than body weight during pregnancy, and there was a small drop in BMR per unit body mass near term. Data on lean body mass (40K) suggest that the small terminal fall in BMR is not explained by a shift in body composition toward increased fat or water. The increase in energy cost of work paralleled the gain in body weight during preganacy. Net energetic efficiency thus appeared to be higher for work performed during pregnancy, if recovery rates are assumed to be uniform. However, according to their heart rate reponses to fixed hard work, the women were less fit during pregnancy than they were postpartum, with the level of fitness decreasing as pregnancy advanced. The prolonged rate of recovery suggests that oxygen uptake may be increased for a longer period after work in the pregnant woman. If this is true, energy expenditure will be seriously underestimated by the application of energy cost figures obtained in the conventional manner.

Adult↗
PubMed1976

Energy expenditure and consumption of mature, pregnant and lactating women.

Activity patterns, energy expenditure, and energy and protein consumption of mature women were determined during preganncy and lactation. Homemakers of average economic status from a mixed population were not significantly more active than teenage women, but the range of activities was greater. Average energy output for the latter half of gestation was 2,200 to 2,300 kcal per day; per unit of body weight, the mean was 32.5 +/- 4 kcal per kilogram for the twenty-week period. A small decline of 6 per cent in energy expenditure was noted near term. Allowing for deposition of fetal and material tissue, the average metabolizable energy need for this group was about 35 to 36 kcal per kilogram for the latter half of pregnancy. These data show that a pregnant woman of reference body weight (68 kg.) may vary in energy output by 800 to 900 kcal per day, depending on occupation. Homemakers with small children and especially those who work outside the home constitute a high energy work category. Thus, the need for considering work pace and work load, as well as body mass, in estimating the energy requirement during pregnancy was confirmed. Average daily energy intake reported was 1,955 kcal or 28.5 kcal per kilogram for the latter half of gestation. A mean protein intake of 1.17 gm. per kilogram per day represented 17 per cent of gross energy consumed. It is questionable whether the energy level consumed by these women was sufficient to maintain positive nitrogen balance on the days recorded. Lactating homemakers expended an average of 30 kcal per kilogram per day, exclusive of milk production. Energy intake was 30 kcal per kilogram, and was equal to 74 per cent of need when adjusted for milk production. Non-lactating women expended 34 kcal per kilogram per day, 13 per cent above the values for lactating women. Average energy intake of non-lactating women was 19 kcal per kilogram, with protein intake representing 19 per cent of energy consumed for both groups.

Adult↗
PubMed1975

Nitrogen balance of men with marginal intakes of protein and energy.

Present protein allowances are based on amounts of nitrogen (N) that maintain balance in adults in laboratory tests. In most tests of minimum N need, energy intakes were higher than present allowances and generally the participants maintained body weight or gained. To evaluate the relative importance of energy and protein intakes in the near-adequate range on the N equilibrium, healthy men were given two levels of protein with energy constant and three levels of energy with protein constant. In the first two 12-day periods, diets provided 5 and 7% of energy (E) from egg white protein with enough E to maintain weight essentially constant (39.6 plus or minus 4.4 kcal/kg). N balance data with these diets were used to select an individual protein intake level nearest to need (5, 6, or 7%), and that level was fed for the next three periods with the same E intake as before (100 E) and 85 or 115% of it. Crude N balance (dietary-fecal-urinary N) was minus0.26 g/day with 5% diet and 0.33 g/day with 7%. Balance was improved by 280 mg/g N fed between these levels. Predicted minimum N need to maintain crude N balance at 100 E is 89 plus or minus 18 mg/kg body weight or 3.76 plus or minus 0.61 mg/basal kcal. N balance fell to minus0.61 g/day with 85 E and increased to 0.59 g/day with 115 E. N balance changed by 174 mg/100 kcal between 85 and 100 E and 112 mg/100 kcal between 100 and 115 E. Energy intake appears to have a much greater effect on N balance than does protein intake in the marginally adequate ranges of intake.

Adult↗