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Biomedical subjects

A Berg

Publications and source records attributed to A Berg.

At least 217 records · Page 12Linked to original sources
PubMed1991

[Metabolic and cardiovascular adaptation and the performance of professional tennis players].

14 professional tennis players of world rank were examined (7 men, mean age 23 +/- 3 years; 7 women, mean age 18 +/- 2 years). Heart volume (HV) was 11.9 +/- 0.9 ml/kg in women, 12.7 +/- 1.3 ml/kg in men, 20-30% higher than in untrained persons. Correspondingly, end-diastolic (EDV) and end-systolic volume, left-ventricular muscle mass (LVM) and stroke volume (SV) were elevated, while contractility parameters as well as the ratios of SV and of LVM to EDV and HV were within normal limits. The changes are to be taken as adaptations in the sense of athlete's heart. Maximal treadmill speed was 18 km/h in women and 19.3 km/h in men, with maximal lactate levels of 9.3 mmol/l (women) and 11.4 mmol/l (men). Anaerobic threshold was reached at a treadmill speed of 13.3 km/h (women) and 14.8 km/h (men). These data indicate a good performance range and were clearly better than in earlier groups of tennis players. This adaptation requires additional interval and endurance training. In 11 tennis players the serum concentration of magnesium and in 5 that of iron was below the recommended lower limit (magnesium: 0.8 mmol/l; iron: 14 mumols/l). Serum concentrations of creatine kinase and of lactate dehydrogenase were always two to three times higher than normal, if tennis training had taken place the day before, but all other biochemical values were within normal limits.

Adaptation, Physiological↗
PubMed1991

Influence of acute maximal exercise on lecithin:cholesterol acyltransferase activity in healthy adults of differing aerobic performance.

To document the possible influence of a single episode of maximal aerobic stress on the serum lecithin:cholesterol acyltransferase (LCAT) activity in subjects with differing histories of training, two groups of healthy male adults [controls (C), n = 18, 28.6 years, SD 5.2, 50.1 ml.kg-1.min-1 maximal O2 uptake (VO2max), SD 5.3; endurance trained athletes (T), n = 18, 31.4 years, SD 8.8, 65.0 ml.kg-1.min-1 VO2max, SD 2.8] were examined in a maximal aerobic stress test. In addition to the routine assessment of lipid status, LCAT activity was measured immediately before and after exercise. At rest nearly identical LCAT activity values were found in both groups: C 64.4 nmol.ml-1.h-1, SD 16.7 vs T 65.0 nmol.ml-1.h-1, SD 20.9. The post-exercise LCAT values induced by the maximal stress test increased significantly to (C) 95.7 nmol.ml-1.h-1, SD 23.5, +48.6%, P less than 0.001; (T) 83.5 nmol.ml-1.h-1, SD 24.3, +29.1%, P less than 0.01. Neither the pre nor the postexercise individual LCAT activity values showed any significant correlation to the corresponding data on physical performance.

Adolescent↗
PubMed1991

Central venous catheter-related complications in newborns and infants: a 587-case survey.

In an attempt to identify factors determining central venous catheter-related complications in newborns and infants, 587 cases have been retrospectively analyzed. Attention has been paid to the influence of the incidence of babies' body weight, site of insertion, and technique of placement of the catheter and the material used, ie, silicone (SI) or polyurethane (PU). Overall complications occurred in 28% of the catheters with 2 deaths due to cardiac tamponade. Mechanical complications happened in 22% of the catheters, including dislodgement (11.6%), extracorporeal perforation (5.3%), and obstruction (5%). Septic complications occurred in 4% catheters, including proven bacteriemia (2.5%), abscess at the entry site (1%), and isolated fever (0.8%). Clinically evident caval thrombosis occurred in 1% of the catheters. Overall complications were significantly higher when the body weight was lower than 2,500 g (P less than .01) due to a significantly higher incidence of septic complications (P less than .05). When a proximal site of placement of the catheter was used, both septic and mechanical complications were more frequent than in the distal approach (P less than .01). The incidence of complications was similar in surgically and in percutaneously placed catheters as in SI and PU catheters. Nevertheless, fatal complications occurred only in PU catheters, leading us to avoid the choice of such material in newborns and small infants.

Body Weight↗
PubMed1991

Immunologic mediators as parameters of the reaction to strenuous exercise.

Both the unspecific and the specific branch of the immune system are triggered and governed by contact and by a set of cytokines, including interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor (TNF). These mediators, which are produced by activated macrophages and other cells, have also multiple (pleiotropic) effects on different cells and organs. While TNF and IL-1 have strongly proinflammatory effects and seem to play a critical role in clinical situations such as septic shock, IL-6 has more restorative effects by being the main inducer of the acute phase response of the liver. The monokines also induce fever and release of ACTH in the brain. Strenuous exercise leads to a significant elevation of cytokines in the serum thereby eliciting an acute phase response. Analysis of systemic cytokines in the serum of marathon runners by the 7TD1 cell line assay revealed that the observed activity is very likely IL-6.

Acute-Phase Reaction↗
PubMed1991

Nocturnal melatonin secretion in thyroid disease and in obesity.

OBJECTIVE: The purpose was to investigate whether the function of the pinealocytes is changed in patients with disturbed metabolic rate or in subjects with marked obesity. DESIGN: Venous blood was sampled every second hour between 1800 and 0800 h, and urine collected between 2200 and 0700 h. PATIENTS: Eight patients with thyrotoxicosis, six with primary hypothyroidism, eight with maturity-onset obesity, and 12 healthy controls were included in the study. MEASUREMENTS: Peak serum melatonin values during the night, total nocturnal melatonin secretion (estimated by melatonin incremental areas), and urinary excretion of melatonin were determined in each participant. RESULTS: Patients with hypothyroidism were found to have higher peak serum melatonin values, total nocturnal melatonin secretion, and urinary excretion of melatonin than normal individuals (Peak melatonin values: 0.55 +/- 0.13 vs 0.27 +/- 0.04 nmol/l, respectively; P less than 0.05. Melatonin incremental areas: 3.38 +/- 0.80 vs 1.45 +/- 0.26 nmol/l h; P less than 0.05. Melatonin excretion: 0.140 +/- 0.023 vs 0.081 +/- 0.013 nmol/9 h; P less than 0.05). Neither of these values differed significantly from the normal in patients with thyrotoxicosis or obesity. Although thyrotoxic patients thus released a normal amount of melatonin during the night, their melatonin secretion peak was phase advanced (melatonin secretion peak appearing at 1.1 +/- 0.5 h in thyrotoxic, and at 3.4 +/- 0.5 h in normal participants; P less than 0.01). No such phase shifts were seen in patients with obesity or hypothyroidism. CONCLUSIONS: These findings imply that both hypothyroid and thyrotoxic patients have disturbed pineal function, which is not the case in patients with obesity. The mechanism underlying these observations remains to be elucidated.

Adult↗
PubMed1991

Further studies of the defective stimulus-response coupling for the oxidative burst in neutrophils in polycythemia vera.

We have previously reported that the chemiluminescence (CL) response of neutrophils (PMN) from patients with polycythemia vera (PV) was abnormally low when induced by surface receptor-dependent stimuli, fMLP and leukotriene B4, but normal when elicited by phorbol myristate acetate (PMA). This study documents that this discrepancy of the CL response to fMLP and PMA remained over a wide range of stimuli concentrations, was not due to iron-deficient PV cells and was also observed with the nitroblue tetrazolium assay. Moreover, another surface receptor-dependent agonist, platelet-activating factor, conferred a significantly lower CL response in PV PMN relative to controls. Treatment with alpha interferon or GM-CSF, to increase fMLP receptors, resulted in a similar enhancement of fMLP-induced CL in PV and controls. CL was normal when induced by a number of non-surface receptor-dependent stimuli. Release of lactoferrin in response to fMLP (and PMA) was normal (as was previously reported fMLP-induced chemotaxis and adherence). Thus, this defect is highly specific for oxidative metabolism, and localized to discrete step(s) of the stimulus-response coupling for fMLP, leukotriene B4 and PAF, but conceivably not due to impairment of the dynamic interaction of fMLP with its receptor.

Aged↗
PubMed1991

Considerations for the treatment of ethylene glycol poisoning based on analysis of two cases.

The clinical picture as well as the principles of treatment in ethylene glycol poisoning differ with the time after ingestion. These time-related differences are illustrated by two case reports. During the first hours of ethylene glycol poisoning, the patient suffers from drunkenness, vomiting and somnolence due to the intoxicant effect of ethylene glycol on the central nervous system. In the following hours a poisoning with glycolate and oxalate develops, with increasing acidosis, renal and brain damage. A patient admitted within a few hours of an overdose, with no or only slight metabolic acidosis, may be successfully treated with ethanol. If the serum concentration of ethylene glycol is very high, hemodialysis may be deferred until the necessary staff and equipment are available. If the patient is admitted with severe metabolic acidosis, hemodialysis must be started immediately. The need for ethanol administration during hemodialysis merits reevaluation.

Acidosis↗
PubMed1991

Gaucher disease: heterologous expression of two alleles associated with neuronopathic phenotypes.

To investigate the molecular basis for the distinct neuronopathic phenotypes of Gaucher disease, acid beta-glucosidases expressed from mutant DNAs in Gaucher disease type 2 (acute) and type 3 (subacute) patients were characterized in fibroblasts and with the baculovirus expression system in insect cells. Expression of the mutant DNA encoding a proline-for-leucine substitution at amino acid 444 (L444P) resulted in a catalytically defective, unstable acid beta-glucosidase in either fibroblasts from L444P/L444P homozygotes or in insect cells. This mutation was found to be homoallelic in subacute neuronopathic (type 3) Gaucher disease. In comparison, expression of the mutant cDNA encoding an arginine-for-proline substitution at amino acid 415 (P415R) resulted in an inactive and unstable protein in insect cells. This allele was found only in a type 2 patient with the L444P/P415R genotype. The substantial variation in the type 3 phenotype (L444P homozygotes) suggests the complex nature of the molecular basis of phenotypic variation in Gaucher disease. Yet, the association of neuronopathic phenotypes with alleles producing severely compromised (L444P) or functionally null (P415R) enzymes indicates that the effective level of residual activity at the lysosome is likely to be a major determinant of the severity of Gaucher disease.

Acute Disease↗
PubMed1991

Clinical and therapeutic use of probucol.

Previous studies showed that probucol significantly lowered both LDL cholesterol and HDL cholesterol. In addition, there is evidence that as an essential antioxidant probucol causes variations in cellular interactions and cardiovascular functions in patients. Therefore, 14 hypercholesterolemic men were investigated before and during probucol treatment in order to document both serological and cardiovascular changes with special regard to (1) serum apolipoproteins (A-I, A-II, B, C-II, C-III, E) (2) composition and distribution of HDL and LDL subfractions, (3) cardiovascular performance using a maximum exercise stress test, and (4) induced platelet aggregation. In contrast to reduced total, LDL-, and HDL-cholesterol values, highly significant changes in serum apolipoproteins were found in apoA-I only; apoA-II was unchanged both in serum and in HDL subfractions. Despite unchanged serum apoB levels, the results showed that probucol has a significant influence on the composition (TG/FC ratio) of LDL particles of d less than 1.019 g/ml. In addition to lipoprotein-related changes, significant decreases in heart rate data and cardiac work and in lactic acid accumulation during exercise were induced by probucol administration; furthermore, adrenaline-induced platelet aggregation was also decreased. The results found significantly demonstrate that probucol acts by way of more mechanisms than cholesterol lowering alone. This aspect may be of special interest in the clinical use of probucol, because a coronary-risk-reducing therapy should not affect the lipoprotein profile only.

Adult↗
PubMed1990

Time-resolved fluorescence studies on mutants of the dihydrolipoyl transacetylase (E2) component of the pyruvate dehydrogenase complex from Azotobacter vinelandii.

Fluorescence anisotropy decays were measured for the wild-type dihydrolipoyl transacetylase (E2) component of pyruvate dehydrogenase complex from Azotobacter vinelandii and E. coli and for E2-mutants from A. vinelandii in which the alanine-proline-rich sequence between the binding domain and the catalytic domain is partially or completely deleted. In both E2-mutants the rotational mobility of the lipoyl domain and the overall activity after reconstitution of the complex are significantly decreased indicating the important role of the deleted sequence for the movement of the lipoyl domain and the transfer of substrates between the different active sites within the complex.

Acyltransferases↗
PubMed1990

[Prevention and therapy of obesity with diet and sports, an ambulatory therapy program for overweight children].

Dietary restriction together with ongoing power-orientated training provide best results in the therapy and prevention of obesity. Diet can reduce the resting metabolic rate by up to 20% within 14 days. Physical activity stimulates the resting metabolic rate and counteracts this energy saving effect, but is especially important for maintaining a steady state after weight reduction. Exercise reduces the risk factors accompanying obesity by favorable adaptation of the sympathoadrenergic system to physical activity. This can be seen in the effects on heart rate, stroke volume, blood pressure, as well as glycogenolytic and lipolytic activities. Body fat especially in the abdominal area, which is particularly connected with atherogenic risk, is diminished. Weight reduction is accompanied by a decrease of the cardioprotective cholesterol fraction. Diets high in unsaturated fatty acids combined with a staying power training have a synergistic effect: they reduce a decrease of HDL. It is difficult to demonstrate risk factors connected with overweight children. However, from the preventive medicine point of view it is advisable to start with therapeutic measures during childhood. In an out-patient pilot project we surveyed 18 obese children aged 9 to 13 years. The therapy plan consisted of dietary restriction (1200 kcal/d), an exercise program performed 3 times a week, and psychological assistance. All children of 12 to 13 years arrived at an overweight level less than 20%, the younger ones displayed a lower weight reduction effect. All 18 improved their aerobic capacity. In the 1st months of treatment, HDL-cholesterol decreased slightly, but increased above pre-treatment level, later on. We did not see any vitamin deficiencies during the therapeutic regimen.

Cardiovascular System↗
PubMed1990

Structure of human low-density lipoprotein subfractions, determined by X-ray small-angle scattering.

The structure of low-density lipoprotein (LDL) particles from three different density ranges (LDL-1: d = 1.006-1.031 g/ml; LDL-3: d = 1.034-1.037 g/ml; LDL-6: d = 1.044-1.063 g/ml) was determined by X-ray small-angle scattering. By using a theoretical particle model, which accounted for the polydispersity of the samples, we were able to obtain fits of the scattering intensity that were inside the noise interval of the measured intensity. The assumption of deviations from radial symmetry is not supported by our data. This implies a spread-out conformation of the apolipoprotein B (apoB) molecule, which appears to be localized in the outer surface shell. A globular structure is not consistent with our data. Furthermore, different models exist concerning the structure of the cholesterol ester core below the phase transition temperature. The electron density data suggest an arrangement in which the steroid moieties are localized at average radii of 3.2 and 6.4 nm. Model calculations show that packing problems can only be avoided if approximately half of the acyl chains of each shell are pointing towards the center of the particle, the other half towards the surface. This arrangement of the acyl chains has never been proposed before. The LDL particles of different density classes differ mainly with respect to the size of the core but also with respect to the width of the surface shells. Model calculations show that the size of different LDL particles can be accurately predicted from the compositional data.

Apolipoproteins B↗
PubMed1990

Effects of age and physical performance capacity on distribution and composition of high-density lipoprotein subfractions in men.

The influences of age and maximal aerobic capacity (VO2max) on serum lipoproteins with special regard to the concentration, composition and distribution of high density lipoprotein (HDL) subfractions were investigated in 51 healthy males of different characteristics: younger than 35 years, untrained (n = 14, mean age 28.2 years, SD 6.0; VO2max, 47.9 ml.kg-1.min-1, SD 5.8) and trained (n = 11, mean age 27.9 years, SD 4.3; VO2max, 61.1 ml.kg-1.min-1, SD 5.1), older than 50 years untrained (n = 14, mean age 58.9 years, SD 5.9, VO2max, 29.3 ml.kg-1.min-1, SD 5.3) and trained (n = 12, mean age 59.3 years, SD 7.2, VO2max, 45.7 ml.kg-1.min-1, SD 7.7). The fasting-state serum concentrations of total cholesterol, tri-acylglycerol and lipoprotein-cholesterol were measured. The HDL-subfractions were separated by density (rho) gradient ultracentrifugation. Concentrations of cholesterol, cholesterylester, tri-acylglycerol, phospholipids, apolipoprotein (apo) A-I and A-II were measured in the subfractions HDL2b: rho = 1.063-1.100 g.ml-1; HDL2al: rho = 1.00-1.110 g.ml-1; HDL2a2: rho = 1.110-1.150 g.ml-1; HDL3: rho = 1.150-1.210 g.ml-1. Elderly untrained subjects showed increased serum concentrations of total-, very low- and low density lipoprotein-cholesterol and elevated tri-acylglycerol levels. The HDL-cholesterol concentration was decreased, due to reduced concentrations of HDL2-subfractions. Significant changes in the composition of HDL2-subfractions were found in elderly untrained subjects. The HDL2-subfractions had more protein, a decreased apoA-I:A-II ratio and less phospholipids in comparison to HDL2-subfractions from younger untrained and trained, and elderly trained subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗