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Biomedical subjects

M W Bates

Publications and source records attributed to M W Bates.

15 recordsLinked to original sources
PubMed1989

Relationships between serum testosterone, fasting insulin and lipoprotein levels among elderly men.

We have previously reported the existence of an association between endogenous male sex hormone and lipoprotein levels in elderly men confined to a nursing home. In a further attempt to elucidate the significance of the association mentioned, we studied the relationship existing in that population between serum testosterone and fasting insulin levels, and between fasting insulin level and lipoprotein pattern. The data were analysed by means of stepwise multiple regression analyses. Serum testosterone and fasting insulin were found to be strongly correlated; this is consistent with the notion that androgen secretion affects directly circulating insulin level. But no independent relationship was demonstrable between fasting insulin and the three lipid-lipoprotein categories studied, namely total serum cholesterol, triglyceride and HDL-cholesterol, suggesting that in this particular population, the effect of male sex hormones upon lipoproteins is not mediated through insulin. Together, these various observations support the belief that androgen secretion affects significantly CAD risk factor levels in elderly men.

Aged↗
PubMed1988

Serum level changes after administration of a pharmacologic dose of beta-carotene.

Results from a pilot study to assess the feasibility of conducting a full-scale lung-cancer-prevention trial using pharmacologic beta-carotene are reported. Participants in the study were randomized in a double-blind fashion to receive either 15 mg orally of beta-carotene or placebo daily. Findings for the first 300 men to complete 1 y on study are presented. After 10 mo of treatment, serum levels in the placebo group showed essentially no change whereas levels in the treated group increased almost 10-fold after 4 mo of treatment. The relationship between change in serum levels are evaluated in regard to body mass index, alcohol consumption, amount of smoking, lipids, and other variables. The results to date clearly indicate that substantial serum response can be achieved with only 15 mg/d and that with this dosage no skin discoloration or other toxicities are observed.

Alcohol Drinking↗
PubMed1986

Determinants of lipid and lipoprotein level in elderly men.

In an effort to better understand the relationship existing between lipoprotein pattern and longevity, we studied the lipid and lipoprotein distribution of 94 men over age 80 who lived in a nursing home, and assessed the role of selective mortality, body mass and sex hormone secretion in determining these distributions. High density lipoprotein subfraction and serum testosterone measurements were obtained on subsamples. The main findings were: (a) Presence of a lipoprotein pattern characterized by low LDL (total serum cholesterol: 179.6 +/- 36.0 mg/dl; LDL cholesterol: 106.3 +/- 31.2 mg/dl) and high HDL2 cholesterol (18.5 +/- 10.2 mg/dl) levels. (b) Occurrence of a positive association between LDL and HDL3 (r = 0.51, P less than 0.01), resulting in an overall high HDL2/HDL3 ratio. Mortality over a 6-month period was directly related to LDL level and possibly inversely related to HDL2 level, suggesting that selective mortality played a major role in determining the pattern observed. Body mass and serum testosterone concentration, which tended to be low, were independently correlated with lipoprotein level; a particularly strong correlation (positive) existed between free testosterone and triglyceride (r = 0.68, P less than 0.01). The latter results suggest that changes related to senescence also influenced lipid and lipoprotein levels.

Aged↗
PubMed1985

The relationship of plasma carotenoids to health and biochemical factors in middle-aged men.

The relationship between plasma carotenoids, plasma cholesterol, cigarette smoking, vitamin supplement use, and intakes of alcohol, vitamin A, and carotene were investigated in 1981 for 187 Multiple Risk Factor Intervention Trial men in Pittsburgh. The total plasma carotenoid value was positively correlated with the dietary carotene and vitamin A indices (estimated by a food frequency questionnaire), vitamin A supplement usage, and plasma cholesterol, and inversely related to cigarette smoking, alcohol intake, and serum aspartate transaminase. The mean plasma carotenoid level was higher in nonsmokers (means = 186 micrograms/dl, 95% confidence interval (CI) 178-195) as compared with cigarette smokers (means = 164 micrograms/dl, 95% CI 151-178) and in vitamin A supplement users (means = 206 micrograms/dl, 95% CI 188-224) as compared with nonusers (means = 172 micrograms/dl, 95% CI 164-179). Variables associated with the total plasma carotenoids in multiple regression analyses included dietary vitamin A and carotene, calorie intake, weekly alcohol intake, cigarette smoking, vitamin supplement usage, and plasma cholesterol, and accounted for 27% of the variance. The total plasma carotenoid value was also highly correlated with plasma beta-carotene (r = 0.67) and lycopene (r = 0.68). The mean beta-carotene (30 micrograms/dl), however, accounted for only 16% of the total plasma carotenoids.

Adult↗
PubMed1976

Blood D-3-hydroxybutyrate and the regulation of plasma concentrations of free fatty acids in the fasted rat.

Acetoacetate or DL-3-hydroxybutyrate were infused into fasted rats at rates comparable to the endogenous rate of ketone body release. Blood samples taken before and during infusion were analyzed for concentrations of ketone bodies, free fatty acids, and immunoreactive insulin. During infusion of acetoacetate or DL-3-hydroxybutyrate, blood concentrations of total ketone bodies doubled. While the HBA/AcAc ratios remained constant in rats infused with DL-3-hydroxybutyrate, the ratios decreased significantly during infusion of acetoacetate, reflecting increases in acetoacetate concentrations without proportionate increases in concentrations of D-3-hydroxybutyrate. Blood concentrations of free fatty acids decreased more rapidly in the rats infused with DL-3-hydroxybutyrate than in the rats infused with acetoacetate. The decrease in free fatty acid concentrations was related to increases in blood D-3-hydroxybutyrate in both the DL-3-hydroxybutyrate-infused rats and in the acetoacetate-infused rats. Plasma immunoreactive insulin concentrations were significantly higher in the DL-3-hydroxybutyrate-infused rats than in the acetoacetate-infused rats. Acetoacetate and DL-3-hydroxybutyrate were infused into depancreatized, functionally hepatectomized fasted rats at rates comparable to those used in the intact fasted rats. Only small decreases in free fatty acid concentrations were observed during infusion. From these experiments it was concluded that increases in blood concentrations of D-3-hydroxybutyrate were more effective than acetoacetate in causing decreases in free fatty acid concentrations in the fasting rat. The pancreas is required for this effect.

Animals↗
PubMed1976

Effects of oleic acid infusion on plasma free fatty acids and blood ketone bodies in the fasting rat.

Oleic acid emulsions stabilized with albumin were infused into fasted rats. Blood samples taken before and during infusion were analyzed for free fatty acids (FFA), ketone bodies, glucose, and insulin. Turnover rates of FFA and ketone bodies were also determined using constant infusion of radioactive tracers. During oleic acid infusions at a rate of 2 mumoles/min/100 g body weight, FFA concentrations increased for a short time and then decreased to preinfusion levels. The decreases in concentrations were due to decreases in the endogenous rates of appearance of FFA into the blood. When oleic acid was infused at a rate of 3.5 mumoles/min/100 g body weight, FFA concentrations increased and remained elevated throughout the infusion. Ketone body concentrations more than doubled during infusions at 2 and 3.5 mumoles/min/100 g body weight and showed no signs of decreasing even when FFA concentrations decreased. Insulin concentrations doubled during infusion and glucose concentrations decreased. Insulin injected during infusion had little effect on concentrations of FFA or ketone bodies. It was concluded that infusions of oleic acid inhibit adipose tissue lipolysis and increase blood ketone concentrations in intact fasted rats. The injection of insulin does not inhibit ketogenesis when blood FFA levels are maintained by infusion.

Animals↗
PubMed1971

Activities of enzymes involved in acetoacetate utilization in adult mammalian tissues.

1. The activities in rat tissues of 3-oxo acid CoA-transferase (the first enzyme involved in acetoacetate utilization) were found to be highest in kidney and heart. In submaxillary and adrenal glands the activities were about one-quarter of those in kidney and heart. In brain it was about one-tenth and was less in lung, spleen, skeletal muscle and epididymal fat. No activity was detectable in liver. 2. The activities of acetoacetyl-CoA thiolase were found roughly to parallel those of the transferase except for liver and adrenal glands. The high activity in the latter two tissues may be explained by additional roles of thiolase, namely, the production of acetyl-CoA from fatty acids. 3. The activities of the two enzymes in tissues of mouse, gerbil, golden hamster, guinea pig and sheep were similar to those of rat tissues. The notable exception was the low activity of the transferase and thiolase in sheep heart and brain. 4. The activities of the transferase in rat tissues did not change appreciably in starvation, alloxan-diabetes or on fat-feeding, where the rates of ketone-body utilization are increased. Thiolase activity increased in kidney and heart on fat-feeding. 5. The activity of 3-hydroxybutyrate dehydrogenase did not change in rat brain during starvation. 6. The factors controlling the rate of ketone-body utilization are discussed. It is concluded that the activities of the relevant enzymes in the adult rat do not control the variations in the rate of ketone-body utilization that occur in starvation or alloxan-diabetes. The controlling factor in these situations is the concentration of the ketone bodies in plasma and tissues.

Acetoacetates↗
PubMed1968

Activity and intracellular distribution of enzymes of ketone-body metabolism in rat liver.

1. The activities of hydroxymethylglutaryl-CoA synthase and lyase in rat liver were found to be two- to 15-fold greater than those reported by other authors under similar conditions. 2. When expressed on the basis of body weight, no appreciable differences were found between the activities of hydroxymethylglutaryl-CoA synthase in whole homogenates of livers from normal and starved rats. The synthase activity increased by 70% and 140% in livers of alloxan-diabetic rats and rats fed on a high-fat diet respectively. 3. Hydroxymethylglutaryl-CoA lyase activity showed no significant increases in starvation or alloxan-diabetes, but a 40% increase was found in fat-fed rats. 4. Less than 12% of the activities of both enzymes were found in the cytoplasmic fraction of normal liver. The cytoplasmic activity doubled in alloxan-diabetes and starvation; on feeding with a high-fat diet the increase, though significant, was less marked. 6. The intracellular distribution of glutamate dehydrogenase indicated that the changes in the cytoplasmic activities observed were not due to leakage from the mitochondria. 7. Feeding with a normal or high-fat diet after 48hr. starvation caused within 24hr. a decrease in the cytoplasmic activity of hydroxymethylglutaryl-CoA synthase to values lower than those found in rats fed on a corresponding diet for a longer period of time. 8. Acetoacetyl-CoA deacylase activity in liver was about 20% of that of hydroxymethylglutaryl-CoA synthase and was primarily located in the cytoplasm. Starvation or alloxan-diabetes did not alter the acetoacetyl-CoA deacylase activity. 9. It is concluded that variations in the concentrations of enzymes involved in acetoacetate synthesis play no major role in the regulation of ketone-body formation in starvation and alloxan-diabetes. The changes in the cytoplasmic activities of hydroxymethylglutaryl-CoA synthase and lyase suggest that acetoacetate synthesis can occur in the cytoplasm. This may play a role in the disposal of surplus acetyl-CoA arising in the cytoplasm when lipogenesis is inhibited.

Acetoacetates↗
PubMed1968

Turnover rates of ketone bodies in normal, starved and alloxan-diabetic rats.

1. Rates of appearance and disappearance of total ketone bodies were determined in normal, starved and alloxan-diabetic rats by measuring specific radioactivities and concentrations of blood acetoacetate and 3-hydroxybutyrate at different times after injection of 3-hydroxy[(14)C]butyrate. 2. The mean rates of appearance were 1.7, 4.2 and 10.9mumoles/min./100g. body wt. respectively for normal, starved and alloxan-diabetic rats. The rates of disappearance were of the same order of magnitude as the rates of appearance. 3. There was a direct correlation between the rates of appearance and disappearance and the blood concentrations of the ketone bodies. 4. The results indicate that in the rat increased ketone-body production is paralleled by increased ketone-body utilization and that the raised ketone-body concentration in the blood in starvation and alloxan-diabetes is due to a slight imbalance between the rates of production and utilization. 5. The findings are discussed in relation to the concept that ketone bodies can serve as fuels of respiration when the supply of carbohydrate is limited.

Acetoacetates↗