Diminished insulin receptors on monocytes and erythrocytes in hypertriglyceridemia

Carbohydrate intolerance is a common observation in endogenous hypertriglyceridemia (HL). So far the nature of this metabolic defect, which accompanies postprandial hyperinsulinemia and a reduced hypoglycemic action of insulin, has not been elucidated. We have examined cellular insulin binding in 20 subjects affected with HL (average plasma triglyceride level, 437 +/- 311 mg/dL) to test the possibility that a receptor defect is involved in peripheral insulin resistance. Monocytes from the HL subjects bound, on the average, 34% less insulin than cells from eight normotriglyceridemic controls of comparable age and body weight (average plasma TG level, 169 +/- 34 mg/dL). Likewise, erythrocytes from the HL group bound 29.6% less insulin than did those from control subjects. Scatchard analysis of the binding data revealed that the number of insulin receptors was reduced for both types of cells. To test if the abnormality in cellular insulin-binding capacity in these subjects is an inherent defect or secondary to the hypertriglyceridemia, 11 of the subjects participated in a 4-month training program (120 minutes weekly of moderate exercise at 60% VO2 max), while the remaining nine persons served as controls. Training reduced the average plasma TG level from 373 +/- 270 to 277 +/- 139 mg/dL (P less than 0.01), but cellular insulin binding was not significantly affected. In addition, no correlation was found between the individual TG plasma concentration and cellular insulin binding. Thus, training itself also proved ineffective in enhancing insulin binding, most probably due to exertion of insufficient intensity.(ABSTRACT TRUNCATED AT 250 WORDS)

[ECG-triggered NMR tomography of the heart]

The technique and scope of ECG-triggered NMR tomography of the heart are described. Correct attachment of the ECG electrodes and cables is important in order to avoid artifacts. The anatomical structure of the heart and mediastinum can be demonstrated with a clarity which has not been possible hitherto in all three planes (axial, frontal, sagittal). This results in considerable advantages when examining abnormal hearts, since it is possible to avoid the risk of contrast media.

[Immunological characterization of unusual plasmacytic tumor cells in a disseminated non-Hodgkin's lymphoma]

Using monoclonal antibodies and heterosera, tumor cells from a disseminated neoplasia were characterized that could not be classified by conventional histology. The large, sometimes multinucleated tumor cells expressed Ia antigens and were positive for immunoglobulins both at the surface and intracellularly (mu, delta, kappa). This tumor was infiltrated by a large number of T cells that comprised about two thirds of the total cell number eluted from the tumor and predominantly were of the suppressor/cytotoxic phenotype. This tumor can be defined as a lymphoma of the B cell lineage with an unusual differentiation exhibiting both Ia antigens and surface immunoglobulins in addition to plasmacytoid markers.

Effect of prolonged exercise on serum lipids and lipoproteins

It has been shown that physical exercise lowers serum triglyceride levels and may increase high density lipoprotein-cholesterol levels. Understanding of the mechanisms responsible for these beneficial adaptations is still incomplete. Twenty-six men, who played soccer continuously for 64 hours to establish a world's record, were monitored for acute changes in lipid metabolism. Food intake was determined before and during the exercise period. Blood specimens were taken before and repeatedly during the match for the measurement of triglycerides (TG), total cholesterol (CH), glycerol, apolipoprotein A-I (apoA-I), and cholesterol in various lipoprotein fractions (quantitative lipoprotein electrophoresis). During exercise TG levels decreased from 116 +/- 26 to 66 +/- 13 mg/dL and CH from 180 +/- 22 to 135 +/- 25 mg/dL. Both TG and glycerol showed an initial increase followed by a continuous decrease. Alpha-CH increased by 19% whereas beta-CH and pre-beta-CH decreased markedly (39% and 78%, respectively). In contrast to alpha-CH, apo A-1 fell only slightly by 10%. These results indicate that the effect of chronic exercise on lipids and lipoproteins can be mimicked by acute prolonged exercise. Similar mechanisms may be involved in these adaptations. Moreover, the extreme length of physical exertion substantially lowered CH.

Reduced uptake and esterification of free fatty acids during prolonged fasting

Nine obese women without hyperinsulinemia fasted 22 +/- 2 d under controlled conditions. Blood was drawn weekly and lipids, lipoproteins, and insulin were determined. In five patients an open fat biopsy was performed before and after fasting and the incorporation of free fatty acids (FFA) into total lipids, diglycerides (DG), and triglycerides (TG) was measured. Glycerol release into the medium was also determined. During fasting triglycerides, total cholesterol, LDL-cholesterol, HDL-cholesterol, glucose, and insulin fell considerably. The uptake and esterification of FFA decreased under both basal and stimulated (norepinephrine) conditions (-11 percent to -23 percent). Basal lipolysis increased slightly by 11 percent. Results indicate that fasting-induced changes in adipose tissue metabolism do not account for the decrease in serum triglycerides. The diminished triglyceride synthesis and the enhanced breakdown of triglycerides in adipose tissue do, however, explain the reduction in adipose tissue mass during fasting.

Treatment of familial hypercholesterolemia with a combination of bezafibrate and guar

The effect of guar (15.6 g/day), a dietary fibre, and simultaneous administration of bezafibrate (600 mg/day) during dietetic treatment on the plasma lipoproteins and apolipoproteins was investigated in 12 patients with familial hypercholesterolemia (corresponding to the HLP type IIa pattern). Either bezafibrate alone or bezafibrate in combination with guar was administered in a cross-over study for 3 months. Guar led to an additional lowering of the total cholesterol in the plasma by 7% (P less than or equal to 0.05) associated with a fall of the low density lipoprotein cholesterol (LDL-cholesterol (LDL-cholesterol) by 13% (P less than or equal to 0.01) without any changes in the very low density lipoprotein (VLDL) and high density lipoprotein (HDL) cholesterols. In parallel with the decrease in LDL-cholesterol, the apoprotein B also was diminished by 20% (P less than or equal to 0.05). The plasma triglyceride level and the triglyceride distribution within the individual lipoprotein fractions were not altered in any consistent manner by the addition of guar. Neither the fasting plasma glucose level nor the body weight were affected. The side-effects due to guar treatment consisted of slight nausea, meteorism and constipation, but this did not in any of the cases lead to early termination of the study. These results demonstrate that guar exerts its cholesterol-lowering effect in addition to that of bezafibrate.

Effect of physical training on insulin uptake by the perfused rat liver

Hepatic uptake of insulin by the in situ perfused rat liver has been measured in rats subjected for 9 wk to physical training (T rats) on a treadmill. Three sedentary groups, one food-restricted (FR) to have the same weight as T rats, one freely-eating (FE), and one sucrose-fed (SF) were also studied. Each liver was cyclically perfused for 30 min with three different insulin concentrations in the medium (approximately 80, approximately 500, and approximately 2000 microunits/ml). Plasma insulin concentrations in T rats were 50 and 17, in FR 55 and 20, in FE 71 and 30 and in SF 84 and 42 microunits/ml in portal and peripheral venous plasma, respectively. Insulin decay curves followed first order kinetics. Taking FE rats as controls physical training enhanced hepatic clearance (expressed in ml/g/min) by 37%-60% whereas sucrose feeding reduced it by 15%-31% during the three perfusion periods. Food restriction in the FR rats caused only minor changes. Similar results were obtained with respect to hepatic extraction ratio and insulin removal. There was a significant negative correlation between portal insulin concentration and hepatic clearance rate. The results indicate that the hepatic extraction of insulin depends on portal insulin concentration. The mean net insulin uptake of the liver was similar in the groups, utilizing portal insulin concentrations and the hepatic clearance rate for calculations. As previously shown, the low peripheral plasma insulin levels after physical training are due mainly to a decreased insulin secretion from the pancreas. This is thus magnified by the efficient trapping of insulin in the liver.

Thyroid hormones and lipolysis in physically trained rats

In rats a single bout of exercise resulted in increased triiodothyronine (T3), thyroxine (T4), and triiodothyronine/reverse triiodothyronine (T3/rT3) ratio 20 hr after exercise. The effect of norepinephrine on lipolysis in vitro was potentiated. In trained rats no changes were found in T4, T3, or rT3 concentrations. The T3/rT3 ratio as well as basal and stimulated TSH concentrations decreased in comparison with sedentary, freely eating rats. Moderate food restriction to produce a body weight similar to that of trained animals caused no changes in T4, T3, or rT3 concentrations but caused a decrease in T3/rT3 and in TSH levels. Training and moderate food restriction groups were not different. T3 in vitro caused a potentiation of catecholamine induced lipolysis in trained and food-restricted animals. With aging the serum concentration of T3 decreased and that of rT3 increased. Acute and chronic exercise both exert an effect on peripheral hormonal responses of lipolysis, while they have different and opposite effects on thyroid hormone concentrations. Physical training seems to have effects in this regard similar to those of moderate energy intake restriction. The results suggest that changes in peripheral effects of thyroid hormones during training should attract more attention.

Plasma C-peptide and insulin in trained and untrained subjects

Plasma insulin and C-peptide were simultaneously determined under various conditions in 11 endurance-trained athletes and 12 nonathletes. Both groups performed an exhaustive ergometer test and an endurance test with 38% of the maximal achieved work load for 45 min. An intravenous glucose tolerance test was also performed. In the basal state, athletes had low plasma insulin and C-peptide concentrations. During exercise, insulin and C-peptide decreased similarly in both groups. In the recovery period, insulin and C-peptide rose within a few minutes. There were differences between the extent as well as the time course of this "rebound" effect after exhaustive or endurance exercise that might be related to glucose alterations. The insulin response but not the C-peptide response after glucose injection was blunted in trained subjects. Results indicate that basal plasma insulin concentrations are lower in athletes due to reduced insulin secretion. During exercise, insulin secretion is diminished independent of the training state. The blunted response of insulin after glucose administration in athletes is due to an enhanced plasma clearance.

Exercise-induced release of pancreatic polypeptide and its inhibition by propranolol: evidence for adrenergic stimulation

Pancreatic polypeptide (PP) has been considered to be predominantly under cholinergic-vagal control and may therefore serve as an indicator of vagal tone. We found similar basal plasma concentrations of PP in athletes with bradycardia and in untrained subjects. We further observed that physical exercise--an adrenergic situation--induces a several-fold rise in PP plasma concentration. Maximal plasma PP levels correlated positively with maximal blood pressure. The exercise-induced rise of PP was completely abolished by propranolol. These findings suggest that stimulation of the adrenergic system releases PP and that therefore plasma PP concentrations cannot be used to determine cholinergic-vagal activity.

[A subjective contrast effect encountered daily by ophthalmologists]

After a brief review of psychophysical contrast effects an example of direct interest to ophthalmologists is illustrated.

Rapid development of immunoprecipitins in agarose gel

A procedure for the rapid development of immunoprecipitins in agarose gels has been developed using polyanion precipitation after immunoelectrophoretical separations. Excellent results are obtained for serum apolipoproteins, immunoglobulins and other proteins. It is shown that quantitative determination of apolipoprotein B in hyperlipemic serum and isolated lipoproteins is affected by immunoprecipitated complexes when rocket immunoelectrophoresis is used. This effect can be avoided by addition of polyvinylpyrrolidone.

Metabolic adaptation to prolonged exercise

A study was undertaken to evaluate and to examine the role of substrate supply in 50 healthy subjects after long distance events, such as 10 km, 25 km, and marathon races. The metabolic, variables of carbohydrate metabolism were greatest in 10-km runners, with the highest increase in glucose, lactate, and pyruvate, while in marathon runners only moderate changes were observed. Marathon competitors gave the greatest decrease in insulin concentration whereas glucagon and cortisol showed a contrary tendency. As for lipid concentrations, the most remarkable point was that after the marathon competition the best runners had the highest increase in free fatty acids; the longer the race, the higher were the beta-hydroxybutyrate and acetoacetate levels after the competition. It is important to emphasize that the limiting factor up to 90 min duration is the competitor's ability to deplete the stores of glycogen. Beyond 90 min (or 25 km) the decrease in insulin, the rise in cortisol and the higher concentration of ketnne bodies found indicate a change in metabnlic response.

Metabolic response to heavy physical exercise before and after a 3-month training period

Twenty healthy athletes performed a heavy physical exercise before and after a controlled training period of 3 months. As a result of physical training there was a reduction in lactate concentration during and after exercise. Plasma free fatty acids and triglyceride levels were lower at rest as well as during and after exercise. Insulin concentrations decreased during exercise before the training period whereas they remained constant afterwards. The composition of individual free fatty acids changed in the same way during exercise before and after training: fatty acids with shorter hydrocarbon chains increased, those with longer chains decreased. Comparing the pattern of individual free fatty acids before and after training a higher percentage of saturated and a lower percentage of mono-unsaturated fatty acids was observed. It is concluded that changes in the plasma free fatty acid profile during heavy exercise reflect a preferential uptake and oxidation of certain individual free fatty acids. The significance of training-induced changes in the plasma free fatty acid pattern is discussed.

Electroretinogram in general medicine

The interest of the usage of the electroretinogram in various fields of general medicine is discussed, with particular regard to endocrinology, ionic changes and neurology. A review from the relevant literature and original contributions from the author's laboratory are reported in detail.

Cardiopulmonary adjustment and metabolic response to maximal and submaximal physical exercise of boys and girls at different stages of maturity

Cardiopulmonary and metabolic variables were investigated at maximal and submaximal bicycle ergometer exercises in 41 swimmers of both sexes, 8--18 years old. VO2 max and VO2 max . HR-1 were higher in boys than in girls and increased with maturity, while VO2 max. kg-1 and HVE were not influenced by this. The HV increased clearly during this growth period, the pubertal and postpubertal subjects showing 16 and 17% higher values for HV and HV . kg-1 than those reported in normal schoolchildren populations. During the submaximal exercise at 70% VO2 max the highest HR values were found in the prepubertal group, whilst the lowest were observed in the postpubertal subjects. These findings suggest that a given percentage of VO2 max as a reference unit, is more reliable than a certain HR to obtain comparable results in subjects with different ages. Blood samples were collected before, during, and after the submaximal exercise. Blood glucose and FFA did not differ in relation to the stages of maturity. During exercise, insulin decreased in prepubertal children, did not alter in pubertal adolescents, and increased in postpubertal subjects. The lactate concentration, during exercise, increased in relation to maturity. The same results were found for HGH, but no differences were found with regard to sex. Since the pattern of HGH secretion during exercise is similar to that found after arginine and insulin administration it is assumed that the same mechanism (i.e., sex hormones) triggers the HGH release.