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Biomedical subjects

U Smith

Publications and source records attributed to U Smith.

At least 181 records · Page 10Linked to original sources
PubMed1983

Effect of different fibers on glucose and lipid levels in diabetic subjects.

The diabetic diet has traditionally been low in carbohydrate content. However, recent studies have shown that the diet may be liberalized in this respect provided that complex carbohydrates are given. When given in amounts corresponding to 50 g starch beans, in particular, raise the blood glucose levels to only a small extent and less than various other foodstuffs tested. The reason for this is, at least in part, due to the effect of the constituent fibers. Guar is another fiber of bean origin which has been shown to lower the postprandial glucose levels. Data from long-term treatment of diabetic patients with guar are presented.

Blood Glucose↗
PubMed1983

Effects of physical training on adrenergic sensitivity in obesity.

To examine the possibility that the decrease of hyperinsulinemia and blood pressure in obesity associated with physical training is mediated via adaptations in the adrenergic nervous system, a pure beta-adrenergic agonist (isoproterenol) or an alpha-adrenergic antagonist (phentolamine) was infused before and during an oral glucose tolerance test before and after physical training. A number of circulatory, metabolic, and endocrine factors under adrenergic control were followed. Physical training was associated with an augmented beta-agonist response in blood pressure, heart rate, blood glucose, plasma insulin, connecting (C) peptide, and pancreatic polypeptide (PP) but not in plasma glucagon and gastric inhibitory polypeptide. Physical training also resulted in higher values of C-peptide and PP values after alpha-adrenergic blockade. It was concluded that physical training probably is associated with an augmented sensitivity of the beta-adrenergic nervous system. This might also be the case with the alpha-adrenergic system. It was suggested that this in turn might be due to a decreased firing in the adrenergic nervous system leading secondarily to an increased sensitivity in the effector cells. It was hypothesized that such decreased firing could provide a background to explain lower blood pressure and plasma insulin after physical training.

Adult↗
PubMed1983

Impact of obesity on metabolism in men and women. Importance of regional adipose tissue distribution.

The distribution of adipose tissue thickness, fat cell weight (FCW), and number (FCN) were studied in four regions in randomly selected middle-aged men and women and in 930 obese individuals. Both the obese and the randomly selected men were found to have the largest adipose tissue thickness in the abdominal region. Women, however, showed a relative preponderance for the gluteal and femoral regions. FCW increased with expanding body fat up to a maximal size of approximately 0.7-0.8 micrograms/cell in each region. After this increase in FCW, a more rapid increase in FCN was found. For the same degree of relative overweight, men had higher triglyceride, fasting glucose, and insulin levels; higher sums of glucose and insulin levels during an oral glucose tolerance test; and higher blood pressure. Furthermore, elevated fasting glucose levels (greater than 7.4 mM) occurred twice as often in the males. These differences between males and females persisted even after body fat matching. A male risk profile was seen in women characterized by abdominal obesity (high waist/hip circumference ratio) as compared to women with the typical peripheral obesity. Stepwise multiple regression analyses in both women and men showed the obesity complications to be associated in a first step to waist/hip circumference or body fat and in a second to abdominal fat cell size. It may thus be concluded that: (a) In both obese and nonobese subjects, regional differences exist between the sexes with regard to adipose tissue distribution. (b) Moderate expansion of body fat is mainly due to FCW enlargement, which is subsequently followed by increased FCN. (c) Men and women with a male abdominal type of obesity are more susceptible to the effect of excess body fat on lipid and carbohydrate metabolism.

Abdomen↗
PubMed1983

Insulin binding and responsiveness in fat cells from patients with reduced glucose tolerance and type II diabetes.

Adipose tissue was obtained from 66 individuals including 21 patients with type II diabetes of different severity (16 SU-treated and 5 diet-treated only) as well as 9 obese subjects with reduced glucose tolerance. Adipocyte insulin binding, antilipolytic effect of insulin, and glucose incorporation into triglycerides were measured in the diabetic and the obese subjects and the data compared with that of normal controls of similar age and relative weight. Insulin binding per cell was normal in the diabetic patients and was significantly increased at low insulin concentrations in the obese patients with reduced glucose tolerance, suggesting increased affinity. Furthermore, insulin binding correlated negatively with age but, when age was corrected for, did not correlate significantly with fasting insulin or glucose levels, relative body weight, or fat cell size. Insulin sensitivity, measured as the antilipolytic effect of insulin, was similar in all patient groups. Patients with the most severe type II diabetes (SU-treated group) demonstrated, in contrast to the less severely diabetic patients, a marked reduction in both basal and insulin-stimulated glucose incorporation into triglycerides showing the presence of a pronounced postreceptor defect. The insulin effect on glucose incorporation correlated negatively with the fasting glucose levels, suggesting that the postreceptor defect seen in the adipocyte reflects perturbations in other organs, like muscle or liver, of greater importance for glucose homeostasis.

Adipose Tissue↗
PubMed1983

Effects of anti-hypertensive therapy on serum lipoproteins. Treatment with metoprolol, propranolol and hydrochlorothiazide.

The effects of metoprolol, propranolol and hydrochlorothiazide on lipoprotein metabolism were studied in three different but comparable groups of middle-aged men with previously untreated hypertension (n=10, n=10, and n=11, respectively). All three treatments were associated with an increase in serum triglyceride and VLDL-cholesterol levels. Propranolol treatment was associated with consistent and significant decreases in HDL-cholesterol, apoA-I and A-II levels, whereas these changes during the other treatments were neither significant nor consistent. An increase in adipose tissue LPL-activity and a decrease in serum free fatty acids were seen in the propranolol treatment group. Significant changes were not observed in glucose tolerance or catecholamine excretion. The blood pressure reduction was similar in the three groups. The design of the present study was in some important respects different from that of others. This may help to explain why we found a difference between the two beta-blockers in our study.

Adipose Tissue↗
PubMed1982

Effect of a modified guar gum preparation on glucose and lipid levels in diabetics and healthy volunteers.

Six healthy volunteers and 17 diabetics (6 insulin-dependent and 11 diet- and tablet-treated) were treated with a special processed, palatable guar gum (10 g b.i.d. immediately before meals) for periods of one or three weeks or, in some cases, up to 13 weeks. A standardized test meal was given to study the effect of the fiber on postprandial glucose levels. Ten g guar was stirred in water and taken immediately before the test meal. The postprandial blood glucose levels were similar in the healthy volunteers but significantly lower in the diabetics following treatment with guar for one and three weeks, respectively. Furthermore, the fasting blood glucose levels were significantly lower in the diabetics after three, but not one, weeks of treatment. The lower postprandial glucose levels were coupled with attenuated and delayed insulin levels in accordance with an effect of guar gum on the rate of carbohydrate absorption. The cholesterol levels were on average reduced with 14% in the diabetics following three weeks' treatment with guar. The higher the initial cholesterol level, the greater the reduction in cholesterol; 26% reduction was achieved in four patients with initial levels above 7 mM. The alpha-lipoprotein cholesterol levels were not significantly changed, thus an increase in the alpha-lipoprotein cholesterol/total serum cholesterol ratio was obtained. Neither plasma triglycerides nor body weights altered during treatment. The reported side-effects were as expected and were usually mild and transient (e.g. increased flatulence). The data show that guar gum also reduces postprandial glucose levels on a long-term basis and may improve the diabetic control. Additionally, treatment with this fiber leads to a concentration-dependent decrease in cholesterol levels.

Adult↗
PubMed1982

Beta-adrenoceptor blockade and recovery from hypoglycaemia in diabetic subjects: normalization after lactate and glycerol infusions.

1. Previous studied have shown that non-selective beta-adrenoceptor blockade attenuates the blood glucose recovery rate after hypoglycaemia in type I diabetes. Apart from possible effects on hepatic glycogenolysis propranolol also inhibits the release of the important gluconeogenic substrates lactate and glycerol. 2. To determine whether the effect of non-selective beta-adrenoceptor blockade on glucose recovery could be associated with diminished availability of gluconeogenic substrates, lactate and glycerol were infused during hypoglycaemia in four insulin-dependent diabetic patients. Comparisons were made of the blood glucose recovery on placebo, propranolol and propranolol combined with the infusion. 3. The blood glucose recovery rate after hypoglycaemia was less on propranolol than with placebo but was significantly improved and not different from placebo when propranolol treatment was combined with lactate and glycerol infusions. Thus, at least for type I diabetic patients, in whom gluconeogenesis is proportionally greater than in healthy subjects, non-selective beta-adrenoceptor blockade attenuates the glucose recovery rate from hypoglycaemia mainly by reducing the availability of gluconeogenic substrates.

Adult↗
PubMed1982

Importance of glucose control for the recovery from hypoglycemia in insulin-dependent diabetics.

To evaluate whether the delayed glucose compensation after hypoglycemia in insulin-dependent diabetics was associated with their elevated blood glucose levels, five diabetic patients were studied before and after a period of intensified metabolic control. The glucose recovery rate was found to be improved after better diabetic control. This influence seems to be better reflected by the mean diurnal level rather than the glucose level immediately before hypoglycemia. The improvement occurred despite the same or lower levels of the important glucocompensatory hormones. These results show the importance of antecedent metabolic control for glucose compensation after hypoglycemia.

Adult↗
PubMed1981

Effect of beta-adrenoceptor blockade on exercise performance and metabolism.

1. Carbohydrate and lipid metabolism and the capacity to perform prolonged submaximal physical exercise were studied in six young healthy subjects treated in a randomized double-blind fashion for 2 days with either placebo, the non-selective beta-adrenoceptor antagonist propranolol (80 mg b.i.d.) or the cardioselective agent metoprolol (100 mg b.i.d.). On day 3, 1 h after the last dose, the subjects exercised for 30 min periods followed up 10 min rest up to the point of exhaustion. 2. The capacity to perform exercise was decreased with both beta-adrenoceptor antagonists. However, at an equal degree of beta 1-adrenoceptor blockade, all subjects could exercise for a longer period of time on the cardioselective agent as compared with the non-selective drug. 3. Blood glucose levels decreased during exercise irrespective of the type of treatment, but the attenuation occurred most rapidly on propranolol. At exhaustion the average non-esterified fatty acid levels had increased 256% on placebo, 148% on metoprolol and 65% on propranolol. A significant positive correlation was found between changes in non-esterified fatty acid levels during exercise and total working time. It is concluded that beta-adrenoceptor blockade diminishes the capacity for prolonged sub-maximal exercise at least in part by reducing the availability of substrates to the working muscles.

Adult↗
PubMed1981

Relation between ST-depression and chest pain in patients with coronary heart disease receiving no treatment and after beta-blockade and combined alpha-beta-blockade.

The bicycle exercise tolerance was studied in ten patients with angina pectoris after one week's treatment with an alpha-beta-blocker (labetalol 300 mg b.d.), alpha-beta-blocker (propranolol 80 mg b.d.) and placebo. The ST-segment of the ECG was continuously evaluated by on-line computerized averaging of complexes which greatly reduces noise and eliminate artefacts caused by varying baseline. Blood pressure was lowest with labetalol and heart rate lowest with labetalol and of heart rate during exercise was equally well depressed by both drugs. They also attenuated ST-depression at a given load but enhanced ST-depression for a given heart rate. At heart rate 100/min ST-depression was significantly greater with propranolol than with labetalol. It is concluded that provided ST-depression during treatment with B-blockers is correlated to myocardial ischemia in the same way as without such treatments used, other factors, e.g. an increase in cardiac size, will contribute more to the ischemia. labetalol may cause less increase in cardiac size than propranolol.

Aged↗
PubMed1981

Distinction between two subpopulations of beta 1-adrenergic receptors in human adipose cells.

The beta-adrenergic receptors in human adipose membranes were identified by the specific and saturable binding of the beta-adrenergic antagonist (--)-[3H]dihydroalprenolol. The total number of sites in control membranes was 0.32 +/- 0.03 pmol/mg protein and the equilibrium dissociation constant for binding (Kd) was 2.6 nM and 2.5 nM as determined by Scatchard analysis of experiments on equilibrium binding and kinetics, respectively. The beta 1-adrenergic nature of the receptors was derived from the order of potencies of beta-adrenergic agonists (isoproterenol greater than norepinephrine greater than epinephrine) to complete with (--)-[3H]dihydroalprenolol for binding. Studies of saturation binding, kinetics and competition binding revealed the presence of a single class of beta 1-adrenergic receptors. Prolonged incubation of human adipose cells in the presence of (--)-norepinephrine decreases the lipolytic response to beta-adrenergic agonists, and reduces by 50% the concentration of beta-adrenergic receptors. The Kd values for (--)-[3H]dihydroalprenolol and the beta-adrenergic agonists remain unchanged. Catecholamines also produce a rapid conformational change of approximatively 50% of the receptors in control membranes as revealed by their increased sensitivity towards inactivation by the alkylating agent N-ethylmaleimide. This inactivation process is not observed in desensitized membranes, which indicates that desensitization and inactivation by agonists plus N-ethylmaleimide affect the same receptor population. The beta 1-adrenergic receptors in human adipocytes can thus be divided into two subpopulations on the basis of the different consequences of their interaction wtih agonist molecules.

Adipose Tissue↗
PubMed1981

Hypoglycemic symptoms in insulin-dependent diabetics. A prospective study of the influence of beta-blockade.

Hypoglycemic attack rate, duration and symptomatology were studied in five insulin-dependent diabetics with borderline hypertension all of whom were prone to hypoglycemia. They were treated in a double-blind, cross-over fashion with the cardioselective beta 1-blocking agent metoprolol and placebo. The treatment period on each drug lasted at least three months. No treatment-associated differences in attack rate and duration of hypoglycemic attacks were recorded. Slight, but no severe masking of hypoglycemic symptoms was recorded in one patient on metoprolol. It is concluded that cardioselective beta 1-blocking agents can be used by insulin-dependent diabetics. However, until further direct experience has been gained caution should be exercised in treating patients with obvious clinical signs of autonomic neuropathy with these drugs.

Adult↗
PubMed1980

The effect of beta-blockade on glucose tolerance and insulin release in adult diabetes.

Blood glucose and plasma insulin levels were studied in ten adult diabetics treated in a cross-over fashion for at least three weeks with alprenolol, a non-selective beta-blocker, or with metoprolol, a cardioselective beta 1-blocker. Dietary intake was controlled three days prior to the study which comprised both i.v. and oral glucose tolerance tests. Mean fasting blood glucose levels were significantly higher on alprenolol than on metoprolol. The increase in fasting blood glucose was particularly pronounced in two patients. In these subjects the glucose tolerance following both an i.v. and an oral glucose load was reduced when treatment was switched from metoprolol to alprenolol. Lower plasma insulin levels in response to glucose were also found in these patients on alprenolol than on metoprolol. The mean insulin levels for all ten patients did not differ significantly between the two treatment periods. These data show that treatment with a non-selective beta-blocker can in some patients cause a considerable deterioration of the glucose tolerance, presumably due to inhibition of insulin release.

Administration, Oral↗