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Biomedical subjects

R Bahr

Publications and source records attributed to R Bahr.

At least 19 recordsLinked to original sources
PubMed2001

Increased neuroendocrine response to a repeated bout of endurance exercise.

This study was designed to compare a first bout of high-intensity endurance exercise with a second bout of similar exercise on the same day, and thereby test the hypothesis that the endocrine response elicited by a second bout is more pronounced compared with a single bout of exercise. Nine male, elite endurance athletes participated in three trials of 24-h duration: 1) complete bed rest (REST), 2) one bout of exercise (ONE), and 3) two bouts of exercise separated by a 3-h rest period (TWO). Each exercise bout consisted of a 10-min warm-up at 50% of VO(2max) followed by 65 min at 75% of VO(2max) on a cycle ergometer. Exercise was performed between 11:00 a.m. and 12:15 a.m. (only in TWO) and 3:15 and 4:30 p.m. (both ONE and TWO). The subjects rested in bed at all hours except when exercising. Blood was sampled 11 times at identical time-points until 7:30 a.m. the next morning. We observed significantly increased levels of epinephrine, norepinephrine, ACTH, cortisol, and growth hormone, and decreased levels of testosterone during and/or after the second bout of exercise compared with the first bout. No difference was observed for insulin, follicle stimulating hormone, luteinizing hormone, thyroid stimulating hormone, free fraction of thyroxin or insulin-like growth factor 1. Thus, this study demonstrates a more pronounced neuroendocrine response to a second bout of exercise on the same day compared with a first/single bout, involving both the sympatho-adrenal system and the hypothalamo-pituitary-adrenal axes.

Adult↗
PubMed2001

Leukocyte counts and lymphocyte responsiveness associated with repeated bouts of strenuous endurance exercise.

This study compared leukocyte counts and lymphocyte responsiveness during and after a second bout of high-intensity endurance exercise on the same day with the response to a similar but single bout of exercise. Nine athletes participated in three 24-h trials: 1) rest in bed (Rest); 2) one bout of exercise (One); and 3) two bouts of exercise (Two). All bouts consisted of 75 min at approximately 75% of maximal O(2) uptake on a cycle ergometer. Lymphocytes in whole blood were stimulated with monoclonal antibodies against CD2 and assessed by flow cytometry for expression of the early activation molecule CD69. The second bout of exercise in the Two trial was associated with significantly increased concentrations of total leukocytes, neutrophils, lymphocytes, CD4(+), CD8(+), and CD56(+) cells and a significantly decreased percentage of CD56(+) cells expressing CD69 compared with a single bout. Additionally, there was a significantly decreased CD69 fluorescence in CD56(+) cells postexercise. These differences suggest a "carry-over" effect in the immune system from a first to a second bout of exercise on the same day.

Adult↗
PubMed2001

No effect of seasonal variation in training load on immuno-endocrine responses to acute exhaustive exercise.

This study was designed to examine the relationship between seasonal changes in training and competition load, and changes in leukocyte subsets, stress hormones, and interleukin-6 (IL-6) in response to a standardised bout of endurance exercise. In addition, changes in mood states were monitored. Ten male, international Nordic skiers, age 20-29, maximal oxygen uptake 70-82 ml x kg(-1) x min(-1) performed the same incremental treadmill tests to exhaustion at the same time of day (+/-1 h), during the competitive season (in-season HI test) and the recovery season (off-season LO test). The subject filled out a training and competition log (TC score) for three weeks prior to each test and a 65-item Profile of Mood State (POMS) test on arrival at the laboratory. Venous blood for haematological, hormonal, and IL-6 analysis was drawn before and at 0, 15, 30, 60, 120 and 240 min after the test. TC score was more than twice as high during the competitive season (16.0 +/- 3.9) compared to the off-season period (7.0 +/- 4.4). An ANOVA procedure for repeated measures showed no difference in exercise induced changes in concentrations of neutrocytes, lymphocytes, epinephrine, ACTH or cortisol between the in-season HI and off-season LO tests; however, norepinephrine and the IL-6 concentrations were elevated at the in-season HI test compared to the off-season LO test. There were no significant differences in POMS global mood score or sub-scores between the in-season HI and the off-season LO tests. Thus, in a group of elite Nordic skiers, we conclude that a doubling of the training and competition load during the winter season does not alter the leukocyte and stress hormone responses to an incremental exercise test to exhaustion.

Adaptation, Physiological↗
PubMed2000

Effect of rhEPO administration on serum levels of sTfR and cycling performance.

PURPOSE: We assessed the possibility of using soluble transferrin receptor (sTfR) as an indicator of doping with recombinant erythropoietin (rhEPO). METHODS: A double-blind, placebo-controlled study was conducted with the administration of 5,000 U of rhEPO (N = 10) or placebo (N = 10) three times weekly (181-232 U x kg(-1) x wk-1) for 4 wk to male athletes. We measured hematocrit and the concentration of hemoglobin, sTfR, ferritin, EPO, and quantified the effects on performance by measuring time to exhaustion and maximal oxygen uptake (VO2max) on a cycle ergometer. RESULTS: Hematocrit increased from 42.7 +/- 1.6% to 50.8 +/- 2.0% in the EPO group, and peaked 1 d after treatment was stopped. In the EPO group, there was an increase in sTfR (from 3.1 +/- 0.9 to 6.3 +/- 2.3 mg x L(-1) , P < 0.001) and in the ratio between sTfR and ferritin (sTfR-ferritin(-1)) (from 3.2 +/- 1.6 to 11.8 +/- 5.1, P < 0.001). The sTfR increase was significant after 1 wk of treatment and remained so for 1 wk posttreatment. Individual values for sTfR throughout the study period showed that 8 of 10 subjects receiving rhEPO, but none receiving placebo, had sTfR levels that exceeded the 95% confidence interval for all subjects at baseline (= 4.6 mg x L(-1)). VO2max increased from 63.6 +/- 4.5 mL x kg(-1) x min(-1) before to 68.1 +/- 5.4 mL x kg(-1) x min(-1) 2 d post rhEPO administration (7% increase, P = 0.001) in the EPO group. Hematocrit, sTfR, sTfR-ferritin(-1), and VO2max did not change in the placebo group. CONCLUSION: Serum levels of sTfR may be used as an indirect marker of supranormal erythropoiesis up to 1 wk after the administration of rhEPO, but the effects on endurance performance outlast the increase in sTfR.

Adult↗
PubMed1999

[In Process Citation]

Mesenteric cysts are a rare cause of disease. In our hospital we treated one patient who suffered from bilateral ureteral obstruction followed by hydronephrosis, caused by a large mesenteric cyst. Because of its extent complete enucleation--the surgical procedure of choice--was not possible. We opened the cyst and made an external percutaneous drainage. After this treatment the patient recovered and even after 6 months there was no recurrence.

Journal Article↗
PubMed1999

An evaluation of root canal preparation with the automated Excalibur endodontic handpiece.

The aim of this study was to evaluate several parameters for automated root canal preparation with the Excalibur handpiece compared with hand instrumentation. The parameters investigated were straightening of curved canals, cleaning ability, working safety (loss of working length, instrument separation, perforation), cross sectional diameter before and after enlargement, and working time. Sixty curved root canals were prepared using the Excalibur handpiece and 30 curved canals with conventional hand instruments to ISO-size 35. The Excalibur left significantly less debris and smear layer on the root canal walls, but hand preparation resulted in fewer unprepared regions. Root canal curvature was well maintained by either technique; the degree of straightening depended on original root canal curvature rather than on the preparation technique. The Excalibur removed significantly more dentin. In the coronal part of the root canal, hand instruments produced significantly more round and oval cross sections; in the middle and apical part no differences could be detected. Working time was shorter for hand preparation, but the difference was not significant. Manual instrumentation proved to be safe; no instrument fracture, perforation or loss of working length could be observed, whereas automated preparation resulted in one perforation and two cases of loss of working length.

Analysis of Variance↗
PubMed1999

An improved technique for the evaluation of root canal preparation.

A device and a method are described for the simultaneous in vitro evaluation of several important parameters of root canal preparation, including root canal cleanliness, straightening, changes in root canal diameter, working safety (loss of working length, apical blockage, instrument fracture, and apical perforation), measurement of apically extruded debris, working time, and practicability. Using a modification of the muffle system described by Bramante et al. (J. Endodon, 13:243-5, 1987), all of these parameters can be investigated simultaneously during preparation of two mesial root canals in extracted mandibular molars.

Evaluation Studies as Topic↗
PubMed1998

Ligament force and joint motion in the intact ankle: a cadaveric study.

The aims of this study were to measure the forces in the anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) and the motion in the tibiotalar and subtalar joints during simulated weight-bearing in eight cadaver ankle specimens. An MTS test machine was used to apply compressive loads to specimens held in a specially designed testing apparatus in which the ankle position (dorsiflexion-plantarflexion and supination-pronation) could be varied in a controlled manner. The forces in the ATFL and CFL were measured with buckle transducers. Tibiotalar motion and total ankle joint motion were measured with an instrumented spatial linkage. The specimens were positioned sequentially at 10 degrees dorsiflexion, neutral, and 10 degrees and 20 degrees plantarflexion, and this sequence was repeated at 15 degrees supination, neutral pronation/supination, and 15 degrees pronation. Force and motion measurements were recorded in each of these positions with and without a 375 N compressive load simulating weight-bearing. From 10 degrees dorsiflexion to 20 degrees plantarflexion, all motion occurred in the tibiotalar joint. In contrast, the ratio of subtalar motion to tibiotalar motion was 3:1 for supination-pronation and 4:1 for internal-external rotation. Inverse loading patterns were observed for the ATFL and CFL from plantarflexion to dorsiflexion. Compressive loading did not affect CFL tension, but it magnified the pattern of increasing ATFL tension with plantarflexion. The largest increase in ATFL force was observed in supination and plantarflexion with a compressive load (76 +/- 23 N), whereas CFL tension mainly increased in supination and dorsiflexion with a compressive load (109 +/- 28 N). In conclusion, the results showed that the ATFL acted as a primary restraint in inversion, where injuries typically occur (combined plantarflexion, supination and internal rotation). Also, the subtalar joint was of primary importance for normal supination-pronation and internal-external rotation.

Adult↗
PubMed1998

Effect of beta-adrenoceptor blockade on postexercise oxygen consumption and triglyceride/fatty acid cycling.

In the recovery period after strenuous exercise, there is increased O2 uptake, termed the excess postexercise O2 consumption (EPOC). One of the mechanisms suggested to explain EPOC is activation of the triglyceride/fatty acid (TG/FA) cycle by catecholamines. The purpose of this study was to determine the effect of selective beta1- and nonselective beta-adrenoceptor blockade on EPOC and the TG/FA cycle. Seven healthy young men each participated in three control and three exercise experiments in a randomized and balanced sequence. In the exercise experiments, subjects exercised for 90 minutes at 58% +/- 2% (mean +/- SD) of maximal O2 uptake on a cycle ergometer, followed by a 4.5-hour bedrest. The control experiments followed the same protocol, but without exercise. In one control and one exercise experiment, the selective beta1-adrenoceptor antagonist atenolol (0.062 mg.kg(-1) body weight) was administered intravenously immediately after the exercise (EXAT) and at the corresponding time in the rest-control experiment (REAT). In a second set of control and exercise experiments, the nonselective beta-adrenoceptor antagonist propranolol (0.15 mg.kg(-1) body weight) was administered (REPRO and EXPRO). In a third set of rest and exercise experiments, an injection of saline was given instead of beta-antagonist (RE and EX). TG/FA cycling was calculated by combining results obtained with a two-stage glycerol infusion and indirect calorimetry. O2 uptake was significantly increased above control levels throughout the recovery period after exercise with the nonselective beta-adrenoceptor antagonist, beta1-adrenoceptor antagonist, and saline. However, there was no difference between the time course or magnitude of EPOC in the three situations. After 4.5 hours of bedrest, the mean increase in O2 uptake was 8% to 9% in all three conditions. TG/FA cycling was increased after exercise, but no effects of beta-antagonists were observed. We conclude that EPOC and the rate of TG/FA cycling are not attenuated by selective beta1- or nonselective beta-adrenoceptor blockade after an acute prolonged exercise protocol.

Adrenergic beta-Antagonists↗
PubMed1998

Effect of beta-adrenoceptor stimulation on oxygen consumption and triglyceride/fatty acid cycling after exercise.

The purpose of this study was to characterize the effects of prolonged beta-adrenoceptor stimulation on O2 uptake and triglyceride/fatty acid (TG/FA) cycling during rest with and without previous exercise. Eight men performed two exercise (90 min cycling at 56 +/- 3 (SD)% of maximal O2 uptake, followed by 4.5 h bed rest) and two rest-control experiments. In one rest and one exercise experiment a bolus dose (5 micrograms) of the beta-adrenoceptor agonist isoprenaline was given immediately after exercise, followed by a continuous infusion (20 ng kg-1 min-1), and at the corresponding time in the rest experiment. In the other experiments saline was given instead. The O2 uptake increased in the post-exercise period both with and without beta-stimulation. The total excess post-exercise oxygen consumption (EPOC) was not different between saline (8.1 +/- 1.8 (SE) L) and isoprenaline administration (10.8 +/- 1.8 L, P = 0.40). Also, the total accumulated increase in O2 uptake for the 4.5 h period after isoprenaline infusion was not different between the rest (12.5 +/- 2.0 L) and the exercise experiments (15.2 +/- 1.7 L, P = 0.40). The rate of TG/FA cycling increased after both exercise and isoprenaline treatment, but no interaction effect was found. In conclusion, the increases observed in O2 uptake and the rate of TG/FA cycling during beta-adrenoceptor stimulation were not increased by a previous exercise bout.

Adrenergic beta-Agonists↗