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Biomedical subjects

R N Myers

Publications and source records attributed to R N Myers.

At least 19 recordsLinked to original sources
PubMed1979

Swine in atherosclerosis research--Development of an experimental animal model and study of the effect of dietary fats on cholesterol metabolism.

The effect of saturated (beef tallow) and polyunsaturated (corn oil) fat diets on plasma cholesterol, bile flow and composition, and excretion of fecal steroids, was studied in 5 female and 6 male miniature swine. The animals were fitted with a modified Baldwin T-tube in the common bile duct for bile sampling and a catheter in the duodenum for reinfusion. Plasma cholesterol levels were increased by beef tallow and decreased by corn oil. Both fats caused an increase in the secretion of bile, biliary lipids and bile acid pool size. The increases were significant when the source of fat was corn oil. The fecal neutral steroid excretion measured in the male swine was increased by both fats. However, only the polyunsaturated fat diet caused a significant increase in the fecal acidic steroid excretion.

Animals↗
PubMed1979

Plasma acetate turnover and oxidation.

Plasma acetate turnover and oxidation were determined in 11 healthy subjects by the constant infusion of a trace amount of [1-14C]acetate for 6 h. The subjects ages ranged from 22 to 57 yr. There was a positive correlation (P less than 0.001) between plasma acetate concentration and turnover rate, and a negative correlation (P less than 0.001) between turnover and age. The plasma acetate concentration in the subjects 22--28 yr old was 0.17 vs. 0.13 mM (P less than 0.02) in subjects 40--57 yr old. The plasma acetate turnover rate was also greater in the younger age group (8.23 +/- 0.66 vs. 4.98 +/- 0.64 mumol/min . kg, P less than 0.01). Approximately 90% of the plasma acetate turnover was immediately oxidized to CO2 in both age groups, however, 13.2 +/- 0.89% of the CO2 output in the younger group was derived from plasma acetate oxidation compared to 7.9 +/- 0.94% in the older group (P less than 0.01). The mean plasma acetate concentration, turnover, and oxidation in six cancer patients 47--63 yr old were similar to the values observed in the age-matched healthy subjects. Uptake or output of acetate by various tissues was measured by arterial-venous plasma acetate concentration differences. In seven of eight subjects undergoing elective surgery, the arterial-portal venous concentration difference was negative, which indicated that the gastrointestinal tract can contribute to plasma acetate production. Uptake of plasma acetate by both the leg and liver appeared to be dictated by the arterial acetate concentration. Net production of acetate by both the leg and liver was most often observed at arterial plasma acetate concentrations less than 0.08 mM.

Acetates↗
PubMed1977

Metabolic response to total parenteral nutrition in cancer patients.

In order to evaluate the metabolic response of nutritionally deprived cancer patients to parenteral nutrition, metabolic parameters including glucose turnover, oxidation, and Cori cycle activity were measured in eight patients before and during short-term (5 to 10 days) i.v. nutrition, with solutions containing amino acids and hypertonic glucose. Before parenteral nutrition, five patients had essentially normal glucose turnover, oxidation, and Cori cycle activity, whereas three patients had moderately increased glucose turnover and markedly increased Cori cycle activity. In response to parenteral nutrition, plasma glucose, insulin, and venous lactate concentration increased and free fatty acid decreased. The percentage of respiratory CO2 from glucose oxidation and the rate of oxidation increased. CO2 production increased, whereas O2 consumption was essentially unchanged. Respiratory quotient rose to greater than 1.0. Endogenous glucose production and high basal Cori cycle activity were decreased. Total parenteral nutrition was judged clinically beneficial in five patients, whereas one patient was unchanged. Deleterious responses, including moderate lactic acidemia, occurred in two of three patients with elevated basal Cori cycle activity.

Adult↗
PubMed1976

Monocarboxylic acids from oxidation of acyclic isoprenoid alkanes by Mycobacterium fortuitum.

Mycobacterium fortuitum utilizes certain stereoisometric mixtures of individual multimethyl branched alkanes as sole carbon source, including 2,6(R), 10(S), 14(RS)-tetramethylhexadecane; 2.6(R), 10(S), 14(RS)-tetramethylheptadecane; 2,6(RS), 10(RS)-trimethyltetradecane, and 2,6(R), 10(S)-trimethylpentadecane. Products of oxidation isolated from the bacterial lipids were acids derived predominantly from oxidation of the isopropyl terminus of each alkane, except in the case of 2,6(RS), 10(RS)-trimethyltetradecane. With the latter, acids from oxidation at either terminus were detected in comparable proportions.

Alkanes↗