PubMed Health⌕ Search

Biomedical subjects

J Böcker

Publications and source records attributed to J Böcker.

10 recordsLinked to original sources
PubMed1998

Ultra-triathlon-related blood-chemical and endocrinological responses in nine athletes.

BACKGROUND: Objective of this study was to get more insight in hematology, biochemistry, and endocrinology of ultra-endurance exercise, to improve knowledge in this field, supplementation, and medical care of affected athletes. METHODS: A large body of individual hematological, biochemical, and endocrinological parameters was analyzed in the blood taken from ultra-athletes before and after completing the 1993 Colmar ultra triathlon covering 7.5 km swimming, 360 km cycling, and approximately 85 km running. PARTICIPANTS: Nine experienced ultra-athletes participated in the study. A follow-up was not possible since the athletes left Colmar within 24 hrs after the contest. RESULTS: The athletes finished the ultra-contest at rankings 4, 5, 7, 8, 9, 11, 18, 22, 23 in a total time between 23:38:53 and 27:54:30 hr:min:sec. Their final body mass (68.6 +/- 1 kg) was significantly lower than at baseline (71.9 +/- 4.2 kg). Non of the athletes made use of medical care. Data after this contest reflect mild hyponatremia, intravascular hemolysis, increased triglyceride turnover, acute-phase reaction, hyperaldosteronemia 2061 +/- 1013 pmol.L-1), hypercortisolemia 971 +/- 486 nmol.L-1), hyper-growth-hormonemia (median 6.8 ng.ml-1), hypoinsulinemia, hypo-free-testosteronemia (42 +/- 17 pmol.L-1), protein catabolism, depressed testicular function, oliguria, and muscle cell leakage. CONCLUSIONS: In our opinion, data presented do not reflect any acute health risks in healthy athletes who are well prepared and carefully supplied during such a contest.

Adult↗
PubMed1998

Monitoring intensive endurance training at moderate energetic demands using resting laboratory markers failed to recognize an early overtraining stage.

BACKGROUND: Aim was to answer the question whether resting laboratory parameters are suitable for monitoring intensive endurance training at moderate energetic demands. This was designed since markers of overtraining at high energetic demands, e.g. mild anemia, leukopenia, iron deficiency, reduced serum albumin, glucose, triglyceride, triglyceride-rich cholesterol (LDL, VLDL), free fatty acid, increased plasma noradrenaline levels, and decreased basal catecholamine excretions were recommended. METHODS: A prospective 6-wk, 6-dys/wk intensive steady state and interval cycle ergometer training of 40-60 min/dy was performed. Total load was about 6-time pretraining activities followed by a 2-wk, 2-hour/wk regenerative training period. Six recreational athletes (VO2max 51.5 +/- 4.5 ml.kg-1.min-1) participated and finished the study. A large pattern of resting hematological, blood-chemical, and hormonal parameters was tested regarding suitability for monitoring overtraining. RESULTS: After 3 wks, submaximum and maximum performance were significantly increased, stopped improving between wk 3 and 6, or deteriorated. No supercompensation occurred after regeneration, but a decrease in work output. Lack of progression and supercompensation, and decreased maximum work output indicate a critical stage in the training process. CONCLUSIONS: All examined resting laboratory parameters failed to reflect this critical stage except for a significant decrease in serum glucose, ferritin, and free fatty acid concentrations.

Adult↗
PubMed1997

Clinical results and radiographic appearance of the Rashkind double umbrella device in patients with occlusion of the ductus arteriosus.

BACKGROUND: The Rashkind double umbrella device for patent arterial duct occlusion has been used in many patients. Its radiographic appearance has not been sufficiently described. OBJECTIVE: To present the varying radiographic appearances of the Rashkind double umbrella device on the chest X-ray. MATERIALS AND METHODS: The chest radiographs of 69 patients (median age 60 months; median weight 17 kg), who underwent closure of their patent arterial duct between March 1990 and August 1994, were reviewed. The following parameters were evaluated: 1) the size of the heart (cardio-thoracic ratio) and pulmonary vessels, 2) the position of the device in AP/PA and lateral projections. The results of occlusion of the patent arterial duct were also reviewed. RESULTS: Sixty-two of 69 (90 %) patients had complete occlusion after a follow-up between 2 months and 3(1)/2 years. The cardio-thoracic ratio showed significant reduction at follow-up (P < 0.001). The two different size devices could be well differentiated in the AP and the lateral projection. In 14 patients (20 %) the device was in an asymmetrical position. There was no significant correlation between position of the device and success of occlusion in our material. CONCLUSION: Complete occlusion of the arterial duct using Rashkind double umbrella devices can be achieved in 90 % of our population. In 20 % the device will have an asymmetrical position. There is no correlation between asymmetrical position of the device in the chest radiograph and residual shunting.

Adolescent↗
PubMed1993

Glucose-induced water movement from the intracellular to the extracellular space and its influence on calculations of glucose metabolism.

The osmotic effect of intravenous glucose was investigated in eight healthy volunteers. Increases in plasma glucose can induce water movement from the intracellular to the extracellular space. Serum choline esterase was used as an endogenous marker of serum dilution. Intravenous tests with 5, 15, 30 and 35 g of glucose showed that the water shift was proportional to the amount infused. The respective dilutions of choline esterase were 1.3 +/- 0.7%, 3.3 +/- 0.9%, 6.3 +/- 0.8% and 7.8 +/- 0.5%. The effect on extracellular water was maintained when plasma glucose remained elevated (inhibition of insulin secretion with a somatostatin analogue). In comparison to glucose, infusion of 10 g of a mixture of amino acids produced a less pronounced effect than expected. The acute water shift after intravenous glucose dilutes serum components including glucose (8% of total extracellular glucose at 35 g). This can be misinterpreted as glucose clearance when calculating metabolic rates. For estimated amounts a proportional correction should be made (3.5% per 5 mmol l-1 increase). A measured plasma glucose of 22.2 mmol l-1 should be corrected to 24.8 mmol l-1, while a plasma glucose value of 5.0 mmol l-1 needs no correction.

Blood Glucose↗
PubMed1991

Molecular dynamics studies of the interface between a model membrane and an aqueous solution.

Molecular Dynamics (MD) computer simulation studies are reported for a system consisting of two model membranes in contact with an aqueous solution. The influence of the membrane on the adjacent liquid is of main interest in the present study. It is therefore attempted to make the system sufficiently large to encompass the entire region between bulk liquid and the membranes. The latter are modeled by two-dimensional arrays of COO- groups with rotational and translational degrees of freedom. The water molecules are represented by the well-tested TIP4P model. The intermolecular potentials are parametrized in terms of Coulomb interactions between partial charges on the molecular frames and empirical, mostly Lennard-Jones (12-6), interactions centered at the atomic positions. A strong layering of the liquid accompanied by an increase in average water density is found in the vicinity of the membrane. The structural perturbation reaches approximately 8 A into the liquid. We discuss the static structure in these layers in terms of atom-atom distance distribution functions and study the average orientation of the water molecule dipoles with respect to the membrane. From the distribution of the ions, we find that less than 50% of the surface charge of the membrane is neutralized by Na+ ions in the first layer above the membrane. A simplified model of the adsorption site of the ion on the membrane is developed from the distance distributions. Finally the hydration of the Na+ in the first adsorbed layer is discussed.

Computer Simulation↗
PubMed1991

Urine screening in outdoor volunteers: day versus night versus 24 hour collection.

Urine constituents were measured in 12 healthy outdoor volunteers on four occasions within a month. Day, night, and 24 hour collection periods were compared. Measurements made on the four occasions did not differ. The amount of water, creatinine, electrolytes, proteins, and enzymes were higher during the day (up to three fold, p always less than 0.05), while equal amounts of amino acids were excreted in the day and the night period. A comparison of all values from all individuals for all four sampling occasions showed that the variation was lowest in the 24 hour samples. Relating the values to creatinine did not consistently reduce the variation. Twenty-four hour samples correlated better with the day than with the night samples. Day and night samples did not correlate. Twenty-four hour collection is superior to day or night collection in healthy outdoor volunteers. Based on the normal variation of values found in the present study, criteria for suspected kidney damage and therefore for the withdrawal of drugs in pharmacological studies can be defined for each collection period.

Adult↗