Sex-hormone-binding globulin and albumin concentrations in human cerebrospinal fluid

Polyacrylamide gel electrophoresis of plasma and concentrated cerebrospinal fluid (CSF) preincubated with tritium labelled 5 alpha-dihydrotestosterone (DHT) showed identical migration of the radioactivity, indicating the presence of sex-hormone-binding globulin (SHBG) in human CSF. The concentrations of SHBG (measured as the binding capacity) and albumin were measured in concentrated CSF (12 women and 1 man) and samples of plasma of some patients (9 women). SHBG could not be detected in 6 of the CSF samples, and the mean value of the determinable samples was 42.3 +/- 13.4 pmol/l. The mean +/- SE of the SHBG concentration in plasma was 90.8 +/- 8.9 nmol/l and the mean albumin concentrations in CSF and plasma were 3.4 +/- 0.6 mumol/l and 670 +/- 107 mumol/l respectively. The distribution ratio for SHBG over the blood-CSF barrier was 10 times higher than for albumin. It was concluded that the SHBG-binding in the CSF is negligible but that the albumin-binding may contribute to the CSF concentrations of testosterone and estradiol, which are 10-25% above the plasma unbound concentrations.     

Comparison of pituitary responses to physical exercise in athletes and sedentary subjects

Serum growth hormone (GH), prolactin (PRL), cortisol, luteinizing hormone (LH), follicle-stimulating hormone (FSH) and thyroid-stimulating hormone (TSH) levels were evaluated before and after a bicycle ergometer exercise test in 8 male competitive volleyball players and in 8 sedentary healthy males of the same age. Increased serum GH and cortisol values after exercise in both groups were found, whereas an exercise-induced PRL release was observed in athletes only. Serum levels of LH, FSH and TSH were unaffected by the test in all subjects. A possible role of training in conditioning the hypothalamopituitary exercise-induced secretion is suggested.     

Cortisol and androgen concentrations in female and male elite endurance athletes in relation to physical activity.

To evaluate the effect of variations in physical activity on selected hormone concentrations in male versus female athletes, fasting serum concentrations of cortisol (C), total-testosterone, free-testosterone, non sex hormone binding globulin (SHBG) bound testosterone, dehydroepiandrosterone, 4-androstene-3,17-dione and SHBG were studied. The tests were performed in nine male and seven female elite endurance athletes during the off-season (test 1), early in the competition season (test 2) and at the end of the competition season (test 3). The C concentration increased significantly during the competition season in women but not in men. Further, the mean C concentrations at test 3 as well as the mean level during the whole observation period (tests 1, 2, 3) were significantly higher in women than in men. No significant changes were found in androgen concentrations or androgen:cortisol ratios within the two groups. The differences between the sexes in C response may indicate different adaptive mechanisms to similar physical stress.     

Plasma levels of renin, angiotensin II, and 6-ketoprostaglandin F1 alpha in endurance athletes

Twelve male runners and 12 matched nonathletes performed a prolonged uninterrupted graded exercise test on the bicycle ergometer up to exhaustion to study blood pressure and plasma levels of renin (PRA), vasoconstrictor angiotensin II (ANG II), and 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha), a metabolite of the vasodilator prostacyclin. In the athletes work load was increased by 30 W/4 min, and in the control subjects the increments of work load were adjusted to their lower exercise capacity to equalize total exercise duration. Blood was drawn, and blood pressure and O2 uptake (VO2) were measured at rest and at the fourth, eighth, and last steps of exercise. Peak VO2 averaged 60 +/- 1.6 ml . min-1 . kg-1 in the runners and 46.8 +/- 1.5 in the nonathletes. To evaluate differences between athletes and controls, PRA, ANG II, and 6-keto-PGF1 alpha were first adjusted for significant confounding factors, such as age, weight, hematocrit, 24-h urinary sodium excretion, and O2 uptake. PRA was significantly lower in the athletes (F = 11.2; P less than 0.01); ANG II was not different at rest, but its rise with exercise was less steep in the runners (F = 8.2; P less than 0.01), whereas 6-keto-PGF1 alpha was not different between the groups (F = 1.3; NS). Despite the differences in PRA and ANG II, however, blood pressure was similar in athletes and nonathletes (F = 0.0; NS).     

Two methods for determining trunk extensor endurance. A comparative study

In the last few years epidemiological surveys have shown correlation between low endurance capacity of the trunk extensors and low back trouble. In this report two methods for the determination of trunk extensor endurance are compared. In method I the fixated subject is lying prone with the cranial border of the iliac crest at the edge of a couch. The endurance time for maintaining the upper part of the body horizontal was measured (max. 240 s). In method II the standing subject performed a horizontal isometric pull on a strain gauge force transducer equivalent to 60% MVC of the trunk extensors. The time until complete exhaustion in the muscles (inability to maintain the preset force level) was determined. The methods were applied to two groups of normal, healthy subjects: 1) 23 female (22-61 years) and 53 male (27-60 years) postmen. 2) 10 male students (20-37 years). The results show that method II is preferable to method I, not least in the field of ergonomics. Method II is easily practicable and does not demand expensive or complicated equipment. Furthermore this method gives reliable results suitable for statistical preparation, and is not influenced by anthropometrical factors.     

Erythrocyte cations and Na+,K+-ATPase pump activity in athletes and sedentary subjects

The chronic effect of training on intraerythrocyte cationic concentrations and on red cell Na+,K+-ATPase pump activity was studied by comparing well-trained athletes with sedentary subjects at rest. Also the acute effect of a 50-min cross-country run on these erythrocyte measurements was studied in the athletes. At rest the intraerythrocyte potassium concentration was increased (P less than 0.01) in the athletes compared to that of the control subjects. The intraerythrocyte concentrations of sodium and magnesium and red cell Na+,K+-ATPase pump activity were, however, similar in the trained and the untrained subjects. As compared with the resting condition, the intraerythrocyte potassium concentration was decreased (P less than 0.05) after exercise in the athletes, and this was accompanied by a minor increase in the intraerythrocyte sodium concentration. Red cell Na+,K+-ATPase pump activity was slightly increased (P less than 0.05) after exercise.     

Intramyocellular lipid content in type 2 diabetes patients compared with overweight sedentary men and highly trained endurance athletes

Recent evidence suggests that intramyocellular lipid (IMCL) accretion is associated with obesity and the development of insulin resistance and/or type 2 diabetes. However, trained endurance athletes are markedly insulin sensitive, despite an elevated mixed muscle lipid content. In an effort to explain this metabolic paradox, we compared muscle fiber type-specific IMCL storage between populations known to have elevated IMCL deposits. Immunofluorescence microscopy was performed on muscle biopsies obtained from eight highly trained endurance athletes, eight type 2 diabetes patients, and eight overweight, sedentary men after an overnight fast. Mixed muscle lipid content was substantially greater in the endurance athletes (4.0 +/- 0.4% area lipid stained) compared with the diabetes patients and the overweight men (2.3 +/- 0.4 and 2.2 +/- 0.5%, respectively). More than 40% of the greater mixed muscle lipid content was attributed to a higher proportion type I muscle fibers (62 +/- 8 vs. 38 +/- 3 and 33 +/- 7%, respectively), which contained 2.8 +/- 0.3-fold more lipid than the type II fibers. The remaining difference was explained by a significantly greater IMCL content in the type I muscle fibers of the trained athletes. Differences in IMCL content between groups or fiber types were accounted for by differences in lipid droplet density, not lipid droplet size. IMCL distribution showed an exponential increase in lipid content from the central region toward the sarcolemma, which was similar between groups and fiber types. In conclusion, IMCL contents can be substantially greater in trained endurance athletes compared with overweight and/or type 2 diabetes patients. Because structural characteristics and intramyocellular distribution of lipid aggregates seem to be similar between groups, we conclude that elevated IMCL deposits are unlikely to be directly responsible for inducing insulin resistance.     

A comparative study of albumin variants found in Brazil

10 rare albumin variants found in Brazil have been compared with 6 others, discovered elsewhere, through horizontal starch gel electrophoresis in four buffer systems. Belém V can be clearly distinguished from Naskapi but shows the same mobility as Máku (= Belém III) in two different pHs. Coari II, Manaus I and Porto Alegre II can be separated from all others in three buffer systems. Belém II (= Mexico) and Belém I also show unique patterns, but Coari I, Porto Alegre I and Belém IV could not be distinguished from Santa Ana. The possibly synonymous Belém III-Belém V-Máku should have originated from an Amerindian gene pool, but Coari I-Porto Alegre I-Belém IV-Santa Ana may have a Caucasoid origin.     

Live high-train low for 24 days increases hemoglobin mass and red cell volume in elite endurance athletes.

The effect of live high-train low on hemoglobin mass (Hbmass) and red cell volume (RCV) in elite endurance athletes is still controversial. We expected that Hb(mass) and RCV would increase, when using a presumably adequate hypoxic dose. An altitude group (AG) of 10 Swiss national team orienteers (5 men and 5 women) lived at 2,500 m (18 h per day) and trained at 1,800 and 1,000 m above sea level for 24 days. Before and after altitude, Hbmass, RCV (carbon monoxide rebreathing method), blood, iron, and performance parameters were determined. Seven Swiss national team cross-country skiers (3 men and 4 women) served as "sea level" (500-1,600 m) control group (CG) for the changes in Hbmass and RCV. The AG increased Hbmass (805+/-209 vs. 848+/-225 g; P<0.01) and RCV (2,353+/-611 vs. 2,470+/-653 ml; P<0.01), whereas there was no change for the CG (Hbmass: 849+/-197 vs. 858+/-205 g; RCV: 2,373+/-536 vs. 2,387+/-551 ml). Serum erythropoietin (P<0.001), reticulocytes (P<0.001), transferrin (P<0.001), soluble transferrin receptor (P<0.05), and hematocrit (P<0.01) increased, whereas ferritin (P<0.05) decreased in the AG. These changes were associated with an increased maximal oxygen uptake (3,515+/-837 vs. 3,660+/-770 ml/min; P<0.05) and improved 5,000-m running times (1,098+/-104 vs. 1,080+/-98 s; P<0.01) from pre- to postaltitude. Living at 2,500 m and training at lower altitudes for 24 days increases Hbmass and RCV. These changes may contribute to enhance performance of elite endurance athletes.     

Plasma interleukin 8 concentrations in obese subjects with impaired glucose tolerance.

Background

Left ventricular hypertrophy (LVH) is a powerful independent risk factor for cardiovascular morbidity and mortality among hypertensive patients. Data regarding relationships between diabetes and LVH are controversial and inconclusive, whereas possible gender differences were not specifically investigated. The goal of this work was to investigate whether gender differences in left heart structure and mass are present in hypertensive patients with type 2 diabetes.

Methods

Five hundred fifty hypertensive patients with at least one additional cardiovascular risk factor (314 men and 246 women, age 52 to 81, mean 66 ± 6 years), were enrolled in the present analysis. In 200 (36%) of them – 108 men and 92 women – type 2 diabetes mellitus was found upon enrollment. End-diastolic measurements of interventricular septal thickness (IVS), LV internal diameter, and posterior wall thickness were performed employing two-dimensionally guided M-mode echocardiograms. LVH was diagnosed when LV mass index (LVMI) was >134 g/m² in men and >110 g/m² in women.

Results

Mean LVMI was significantly higher among diabetic vs. nondiabetic women (112.5 ± 29 vs. 105.6 ± 24, p = 0.03). In addition, diabetic women presented a significantly higher prevalence of increased IVS thickness, LVMI and left atrial diameter on intra-gender comparisons. The age adjusted relative risk for increased LVMI in diabetics vs. nondiabetics was 1.47 (95% CI: 1.0–2.2) in females and only 0.8 (0.5–1.3) in males.

Conclusion

Type 2 diabetes mellitus was associated with a significantly higher prevalence of LVH and left atrial enlargement in hypertensive women.     

Upper body muscle strength and endurance in relation to peak exercise capacity during cycling in healthy sedentary male subjects

The aim of this study was to investigate the relation between upper body muscle strength and endurance, and exercise capacity during an incremental cycle exercise test in sedentary healthy male subjects before and after 6 months of combined supervised group training. Exercise capacity was measured as maximal oxygen consumption (VO?peak) and maximum work rate (WR(peak)). Muscle strength and endurance of the upper body were assessed by bench press and isometric measurement of trunk extensor and flexor maximum voluntary contraction (MVC) and trunk extensor and flexor endurance. Thirty-one subjects were studied before and after the training period. Bench press and trunk extensor MVC correlated to exercise capacity at baseline and after training. Training improved VO?peak and WR(peak). The correlation between trunk extensor MVC and exercise capacity improved after training. Upper body strength may affect exercise capacity by increasing the rider's ability to generate force on the handlebar that can be transmitted to the pedals. Resistance training of the arms, chest, and trunk may help improve cycling performance.     

Tissue cholinesterases. A comparative study of their kinetic properties

The substrate saturation and temperature-dependent kinetic properties of soluble and membrane-bound forms of acetylcholinestarase (AChE) from brain and butyrylcholinesterase (BChE) from heart and liver were examined. In simultaneous studies these parameters were also measured for AChE in erythrocyte membranes and for BChE in the serum from rat and humans. For both soluble and membrane-bound forms of the enzyme from the three tissues, two components were discernible. In the brain, Km of component I (high affinity) and component II (low affinity) was somewhat higher in membrane-bound form than that of the soluble form components, while the Vmax values were significantly higher by about five fold. In the heart, Km of component II was lower in membrane-bound form than in the soluble form, while Vmax for both the components was about four to six fold higher in the membrane-bound form. In the liver, Vmax was marginally higher for the two components of the membrane-bound enzyme; the Km only of component I was higher by a factor of 2. In the rat erythrocyte membranes three components of AChE were present showing increasing values of Km and Vmax. In contrast, in the human erythrocyte membranes only two components could be detected; the one corresponding to component II of rat erythrocyte membranes was absent. In the rat serum two components of BChE were present while the human serum was found to possess three components. Component I of the human serum was missing in the rat serum. Temperature kinetics studies revealed that the Arrhenius plots were biphasic for most of the systems except for human serum. Membrane binding of the enzyme resulted in decreased energy of activation with shift in phase transition temperature (Tt) to near physiological temperature.     

Plasma volume changes in middle-aged male and female subjects during marathon running

Circulatory fluid shifts were studied in middle-aged runners (6 males and 5 females, ages 32-58 yr) during a 42.2-km marathon race run in mild weather (dry-bulb temperature = 17.5-20.4 degrees C). Running times for the subjects were 3:12-4:40 (mean values were 3:34 for males and 4:10 for females). Venous blood samples were taken without stasis in all subjects seated at rest before the start of the race and within 3 min of finishing; eight of the subjects also paused for samples at 6 and 27 km during the race. At 6 km, body weight loss averaged less than 1%, whereas plasma volume (PV) had decreased by 6.5% in male subjects and 8.6% in female subjects. By the end of the race, hypohydration had reached 3.2% in male subjects and 2.9% in female subjects, but PV in both groups remained stable. Sweat rates during the race averaged 545 and 429 g X m-2 X h-1 for male and female subjects, respectively, with ad lib. water intake replacing 21-72% of fluid loss. Increases in plasma protein concentration throughout the race reflected the observed initial decrease in PV. The interpretation of PV responses to exercise and/or hypohydration is critically dependent on selection of base-line conditions; we were able to control for posture-exercise effects by treating the early exercise (6 km) sample as the base line for examining the effects of later fluid loss. Under these conditions, the vascular compartment resisted volume depletion. The ability to maintain stable PV can be explained in part by relationships among oncotic and hydrostatic pressures in the intra- and extravascular fluid compartments.     

Effects of three day bed-rest on circulatory, metabolic and hormonal responses to oral glucose load in endurance trained athletes and untrained subjects

Endurance trained long distance runners and untrained individuals underwent three days of bed rest and oral glucose loading. Before and after bed rest, individuals were given glucose tolerance tests, and their heart rates, blood pressure, blood glucose levels, insulin levels, and catecholamine interactions were measured. Results indicated that glucose tolerance is more affected by bed rest-induced deconditioning in untrained individuals than in trained individuals.     

Non-exercise daily energy expenditure and physical activity pattern in male endurance athletes.

The present study was performed to determine whether differences in non-exercise daily energy expenditure (Md,ne) exist between trained and untrained individuals. The data from seven cross-country skiers were compared with those from eight sedentary men. Daily energy expenditure (Md) was determined using the heart rate-oxygen consumption relationship; resting metabolic rate (Mr) was measured using indirect calorimetry. A physical activity questionnaire and ratios of Md or Md,ne to Mr were used as indices of physical activity. Md and Mr were significantly higher in the trained subjects whereas Md,ne was identical in the two groups. The ratio of Md,ne to Mr and the data from the physical activity questionnaire showed that there was no significant difference in daily energy expenditure and physical activity pattern during the non-exercise time. These results suggest that the exercise-induced increase in daily energy requirements is not compensated by a more sedentary life during the other daily activities in these trained men.