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Biomedical subjects

W M Rand

Publications and source records attributed to W M Rand.

At least 55 records · Page 3Linked to original sources
PubMed1990

Prognostic significance of ventricular blood in supratentorial hemorrhage: a volumetric study.

We reviewed CTs from 47 patients with 48 spontaneous, supratentorial brain hemorrhages to determine the effect of ventricular blood on outcome. We correlated volumetric analysis of the parenchymal (P) and ventricular (V) blood, as well as other clinical and CT features, with clinical outcome in a statistical analysis. Hemorrhages were located in putamen 20/48 (42%), thalamus 13/48 (27%), lobar 9/48 (19%), caudate 3/48 (6%), and miscellaneous locations 3/48 (6%). Outcome in putaminal hemorrhages was highly correlated with the total (P + V) and P blood volumes, whereas the V blood was less important. For thalamic hemorrhages, outcome correlated more highly with the V and P + V volumes than with the P portion. Outcome for all hemorrhages was significantly correlated, in descending order of importance, with the severity of the initial neurologic deficit, P + V blood, hydrocephalus, the number of ventricles containing blood, P, V, and blood in the 4th ventricle. In general patients with more than 20 cc of V blood did poorly. Although hydrocephalus was associated with poor outcome, ventricular drainage did not benefit 8 of 9 patients.

Aged↗
PubMed1987

Lipogenesis from ketone bodies in the perfused rat liver: effects of acetate and ethanol.

The interactions between acetate or ethanol metabolism, lipogenesis, and ketone body utilization have been studied in isolated livers from fed rats perfused with 15 mM glucose and 10 mM acetate or ethanol. The contribution of acetate to ketogenesis is constant; on the other hand, the contribution of ethanol to ketogenesis increases with time, presumably because of the accumulation of acetate in the perfusate. Ketogenesis is decreased in the presence of ethanol (but not acetate), while ketone body utilization is not affected by ethanol or acetate. Acetate contributes one third and ethanol contributes one half of the carbon incorporated into fatty acids and 3-beta-hydroxysterols. Only a small fraction (less than 5%) of the incorporation of acetate or ethanol into fatty acids and sterols occurs via transient incorporation into ketone bodies.

Acetates↗
PubMed1987

Leucine kinetics during three weeks at submaintenance-to-maintenance intakes of leucine in men: adaptation and accommodation.

Previous results of short-term diet studies of leucine kinetics have suggested that the currently accepted requirement value for the amino acid in adults is too low. In the present study the effects of a more prolonged diet period at low leucine intakes on leucine kinetics and nitrogen balance (NB) were explored in healthy young men. They (4 or 5 subjects per group) received an adequate leucine intake (80 mg/kg/d) for 1 or 2 weeks (Period 1) followed by either 7, 14 or 30 mg/kg/d for 3 weeks (Period 2) with a return to 80 mg/kg/d for 1 week (Period 3). Estimates of leucine fluxes (LF), oxidation (LO) and balance (LB) were based on a constant intravenous infusion of L-[1-13C]leucine, at end of Period 1, at 1 and 3 weeks of Period 2 and on days 1 and 3 of Period 3. At all three intakes LF and LO, during the fed state, fell between 1 and 3 weeks of Period 2. LB was negative at 1 week of Period 2 for all groups but had approached equilibrium by 3 weeks. N balance at 3 weeks was similar for all groups but during Period 3 was significantly higher (P less than 0.05) and markedly positive (+18 mgN/kg/d) for the 7 and 14 mg groups, compared with the 30 mg group (+4 mgN/kg/d), indicating that 'depletion' had occurred at the lower leucine intakes during Period 2. Our interpretation is that LB was approached by an adaptation in the 30 mg group whereas it was achieved in the 7 and 14 mg groups by an accommodation, associated with a reduced and low rate of leucine uptake into protein (LF minus LO). Thus, the leucine requirement was judged to be greater than 14 mg/kg/d, a level currently accepted as the upper range of the requirement for healthy adults. The significance of these findings for assessment of nutrient requirements is discussed, with emphasis on the limitation of NB measurements for evaluation of human amino acid requirements.

Adaptation, Biological↗
PubMed1985

Retrospective analysis of data from five long-term, metabolic balance studies: implications for understanding dietary nitrogen and energy utilization.

Daily urinary nitrogen (N) excretion and body weight data of 42 healthy young adults, who received constant, adequate diets for up to 90 days, and maintained constant level of physical activity, were examined retrospectively. From the N excretion data, it was determined that, when corrected for long-term trends, daily variability was random and much larger than variability due to the long-term trends. Thus, N balance data based on commonly used diet periods of about 2 wk adequately estimates population variability. Body weight data for most subjects showed significant changes and many subjects experienced persistent linear changes throughout the entire experimental period. Thus, for most healthy young adults, neither dietary-induced thermogenesis nor changes in the efficiency of energy utilization appears to play a quantitatively important role in the maintenance of body weight (and body composition) in response to relatively modest discrepancies between the level of food intake and energy intake needed to balance initial total energy expenditure. The key importance of food intake regulation and/or physical activity in weight maintenance is emphasized by these findings.

Adolescent↗
PubMed1984

Report of a planning conference concerning an international network of food data systems (INFOODS).

A small international planning conference on the topic of "An International Network of Food Data Systems" was held on January 30 to February 5, 1983, at the Rockefeller Conference and Study Center, in Bellagio, Italy. It was sponsored through the Food, Nutrition and Poverty Subprogramme of the United Nations University and supported by various US government agencies, private foundations, and the food industry. Participants included representatives from FAO, WHO, IUNS, and IUFoST. The purpose was to explore the needs for, and current limitations of, food composition data bases, especially in the international context, and to propose what was needed. The conference focused on the design and scope of an organization to be called INFOODS (International Network of Food Data Systems) which would promote international participation and cooperation in the acquisition and interchange of quality data on the nutrient composition of foods, beverages, and their ingredients in forms appropriate to meet the needs of government agencies; nutrition scientists; health and agriculture professionals; policy makers and planners; food producers, processors, and retailers; consumers. The conference identified the more important aspects of INFOODS to include: 1) a network of regional data centers; 2) an organizational/administrative framework for various expert task forces; 3) the generator and repository of special international data bases; 4) the stimulator of national data base programs; 5) a general and specific resource for persons and organizations interested in food composition data on a worldwide basis.(ABSTRACT TRUNCATED AT 250 WORDS)

Computers↗
PubMed1984

Evaluation of the protein quality of an isolated soy protein in young men: relative nitrogen requirements and effect of methionine supplementation.

The protein nutritional value of an isolated soy protein (Supro-620) was evaluated in a series of nitrogen balance studies in healthy young male MIT students. Experiment 1 involved giving eight subjects graded intakes of the isolated soy protein while seven additional subjects received egg protein. Mean nitrogen intake required for N balance for the isolated soy protein and the egg protein were not significantly different (p greater than 0.1). In experiment 2, nine subjects received soy and the effects on N balance at various levels of L-methionine supplementation were studied. In experiment 3 eight subjects each were studied at two nitrogen intake levels of isolated soy protein/kg/day with methionine supplementation, and an unsupplemented egg protein period included. Results from experiment 2 and 3 at an 82 mg N/kg/day test level showed that N balance for 1.6% supplementation was significantly below that of unsupplemented egg while 1.1% and unsupplemented soy were indistinguishable from egg. No beneficial effects of methionine supplementation were observed when the test nitrogen intake level was 128 mg N/kg/day. These results indicate that for healthy adults, the isolated soy protein is of high nutritional quality, comparable to that of animal protein sources, and that the methionine content is not limiting for adult protein maintenance.

Adult↗
PubMed1984

A long-term metabolic balance study in young men to assess the nutritional quality of an isolated soy protein and beef proteins.

To evaluate the capacity of an isolated soy protein to maintain long-term protein nutritional status in healthy young adult men, an 84-day metabolic balance experiment was conducted in eight subjects. The sole source of protein intake was provided by the isolated soy protein, given at a level of 0.8 g (N X 6.25) per kg per day. In a second and similar study, four young men received 0.8 g protein and three subjects 0.68 g protein per kg per day from beef proteins for 60 to 81 days. Body weight, nitrogen balance, blood chemistries, and body composition (whole body 40K) were monitored throughout each study. Body nitrogen balances were maintained within the range of N equilibrium in both diet groups. Body cell mass, as judged from 40K measurements, did not reveal any deterioration in protein nutritional status. These observations confirm the prediction, derived from previous short-term. N balance studies, that the nutritional quality of isolated soy protein is high and that this plant protein can serve as the sole source of essential amino acids and nitrogen for protein maintenance in adults.

Adolescent↗
PubMed1983

Nitrogen balance studies in young men to assess the protein quality of an isolated soy protein in relation to meat proteins.

The protein nutritional value of an isolated soy protein was examined in healthy young men during 10-day N-balance periods. In the first study (expt 1), 10 young men received a diet providing a test protein (N X 6.25) intake of 0.6 g protein per kilogram per day with nitrogen from either lean beef, isolated soy protein or various combinations of the two sources. No differences in N balance, digestibility or net protein utilization were observed when the soy protein replaced beef. In the second study (expt 2), three separate groups of seven young men each received graded intakes of either beef or an isonitrogenous mixture of beef and the isolated soy protein or dried skim milk. An estimate was made of the N intake from each source required for N equilibrium. These values were 116, 106 and 103 mg N/kg per day, respectively. No statistically significant differences were found among the three dietary groups. Thus, the protein quality of the isolated soy protein appears to be comparable to that of animal protein sources such as milk and beef.

Adolescent↗
PubMed1983

Nitrogen balance response in young men given one of two isolated soy proteins or milk proteins.

The protein nutritional value of two isolated soy proteins was compared with that of dried skim milk proteins in healthy young men. Eight subjects received one of the isolated soy proteins and six subjects received the dried skim milk as the test protein source. Each protein was tested at intakes of 0.35, 0.45, 0.55 and 0.65 g protein (N X 6.25) per kilogram per day during 10-day diet periods separated by break periods of 3 days and a 1-day protein-free period. Nitrogen balances were determined for the final 5 days of each experimental diet period. From regression analysis of nitrogen intake minus nitrogen output data, intakes of each protein source to meet mean nitrogen requirements were 124, 146 and 144 mg N/kg per day for the two isolated soy proteins and skim milk protein, respectively. It is concluded that well-processed isolated soy proteins are indistinguishable from milk as a protein source for maintenance of short-term N balance in adult human nutrition.

Adolescent↗
PubMed1982

Underestimation of metabolic rates owing to reincorporation of 14CO2 in the perfused rat liver.

(14)CO(2) production by perfused rat livers was simulated by infusing NaH(14)CO(3) into the perfusate. Recovery of label as (14)CO(2) gas + perfusate bicarbonate was 45-85%. Rates of (14)CO(2) exchange in the liver are 3-70 times greater than net rates of CO(2) production. Therefore (14)CO(2) reincorporation can lead to significant underestimations of rates of oxidation of (14)C-labelled substrates in liver.

Animals↗
PubMed1980

Nitrosamine carcinogenicity: a quantitative relationship between molecular structure and organ selectivity for a series of acyclic N-nitroso compounds.

A mathematical model has been developed which describes the selectivity between liver and other target organs for a series of carcinogenic N-nitro-sodialkylamines. The relationship requires structural terms for the parent molecule as well as for the potential metabolites. This suggests that the nitrosamine metabolites are involved in tumor induction and that they participate directly in the mechanisms responsible for selecting the target organ.

Animals↗
PubMed1979

An analysis of temporal patterns in urinary nitrogen excretion of young adults receiving constant diets at two nitrogen intakes for 8 to 11 weeks.

The temporal pattern of daily urinary nitrogen (UN) excretion was investigated in 21 young adult men and women who participated in two metabolic studies involving constant diets and lasting 8 to 11 weeks. For one group (16 subjects), nitrogen (N) intake was about 280 mg N/kg per day (mixed animal and plant protein sources) for 8 weeks; for the second group (five subjects), N intake was about 90 mg N/kg per day (egg protein) for 11 weeks. Two mathematical models were examined to determine how well they described the variations in UN. The first modeled only random variability while the second added a component of serial correlation (correlation between successive daily observations). After correcting the UN data for linear trend, to minimize effects of possible alterations in body composition, only two of the 21 subjects showed significant serial correlation of daily UN. Moreover, it is shown that any serial correlation undetectable in these data would not be of practical importance in estimating UN levels in short-term dietary experiments. It is concluded that the interpretation of metabolic N balance measurements involving constant N intakes over relatively short dietary periods in not complicated by cyclic, time-dependent variations in UN.

Adolescent↗
PubMed1979

Diurnal variations in plasma concentrations of tryptophan, tryosine, and other neutral amino acids: effect of dietary protein intake.

The effect of dietary protein content on the diurnal variations in plasma neutral amino acid levels was studied in normal human subjects. For three consecutive 5-day periods, subjects consumed diets containing 0, 75, or 150 g of egg protein per day. Blood samples were drawn at 4-hr intervals on the 4th and 5th days of each period. Consumption of the protein-free diet caused plasma concentrations of all amino acids studied to fall in the late morning and afternoon, while the 150-g protein diet elicited increases in these levels during the daytime. Ingestion of the diet containing 75 g of egg protein tended to diminish the amplitudes of the daily rhythms in plasma amino acid levels, but most amino acids still exhibited small but significant elevations late in the evening. At all times of day, plasma concentrations of the large neutral amino acids studied (i.e., aromatic and branched-chain amino acids, and methionine) varied directly with the protein content of the diet. In contrast, the relationships between dietary protein content and the plasma concentrations of glycine and alanine, two small neutral amino acids, were inverse. The ratios of plasma tryptophan, tyrosine, and phenylalanine levels to the sum of the concentrations of other large neutral amino acids tended to fall as the protein content of the diet was increased. The corresponding ratio for valine increased as protein was added to the diet, while the leucine and isoleucine ratios were not correlated with dietary protein content. Since diet-induced changes in plasma trypotphan and tyrosine ratios in animals are known to cause parallel alterations in brain tryptophan and tyrosine levels, and thus in the rates of brain serotonin and catecholamine synthesis, our data suggest that ingestion of carbohydrates and protein may also normally affected brain monoamine synthesis in humans.

Adult↗
PubMed1979

Diurnal variations in plasma neutral amino acid concentrations among patients with cirrhosis: effect of dietary protein.

The effect of varying dietary protein content on the daily rhythms in plasma neutral amino acid concentrations was studied in patients with chronic cirrhosis. For two consecutive 5-day periods, subjects consumed diets containing either 0 or 75 g of protein per day. Blood samples were drawn at 4-hr intervals on the 4th and 5th days of each dietary period. For most of the neutral amino acids, the changes in plasma concentration associated with time of day or with variations in dietary protein content were similar to those observed previously in normal subjects. Ingestion of the protein-free diet caused significant reductions in the daytime level of all amino acids studied, except for tryptophan, the concentration of which did not change during the 24-hr period. Ingestion of the 75-g protein diet caused plasma levels of most of theamino acids to increase slightly during the day; these increments were not statistically significant for tryptophan, tyrosine, leucine, and methionine. The absolute plasma concentrations of most of the neutral amino acids were also in the normal range; exceptions included methonine, tyrosine, and phenylalanine, whose plasma levels were significantly elevated above normal valves. The plasma ratios of tryptophan, tyrosine, and phenylalanine concentrations to the sum of the concentrations of other large neutral amino acids increased during the day uhen the protein-free diet was ingested; this effect was moderated by the addition of protein to the food. The plasma ratios for the branched-chain amino acids were depressed below normal; those for tyrosine, phenylalanine, and methionine were significantly increased. The plasma tryptophan ratio was within the normal range. These findings provide a basis for anticipating that the uptake from blood into brain of several of the large neutral amino acids may be modified in patients with chronic cirrhosis.

Adult↗
PubMed1978

Nitrosamine carcinogenicity: a quantitative Hansch-Taft structure-activity relationship.

Statistically significant correlations have been demonstrated between carcinogenic activity, water-hexane partition coefficients and electronic factors for an extensive series of N-nitroso compounds. Electronic factors were expressed by the Taft sigma* values of substituents on the carbon atoms alpha to the N-nitroso group. Such correlations indicate that transport of the carcinogen to its active site has an important effect on its potency. The correlations also implicate reactivity at the alpha-carbon in the determination of carcinogenic activity and point out various structural types which do not follow the general rule.

Animals↗