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R Beneke

Publications and source records attributed to R Beneke.

31 records · Page 2Linked to original sources
PubMed1997

Moderate exercise leads to decreased expression of beta1 and beta2 integrins on leucocytes.

Intravascular adhesion of leucocytes plays a role in the pathogenesis of acute and chronic vascular disease. Regular aerobic exercise seems to protect against vascular disease. Since leucocyte adhesion is mediated by integrins, we tested the hypothesis that surface expression of the integrin adhesive receptors LFA-1 (cd11a/cd18), MAC-1 (cd11b/cd18), gp 150/95 (cd11c/cd18), and VLA-4 (cd29/cd49) is decreased by moderate endurance exercise. Surface expression of integrins was measured by FACS analysis in 19 healthy subjects (16 males, 3 females, 36.6 +/- 8.7 years, 177.1 +/- 7.5 cm, 70.3 +/- 8.1 kg) before and after submaximal exercise (3 h run) using monoclonal antibodies against cd11a, cd11b, cd11c, cd18, cd29 and cd49. In addition, we compared resting integrin expression in this group with a group of sedentary subjects (19 males, 6 females, 29.3 +/- 5.3 years). White blood cell count increased from 5300 ml(-1) to 9740 ml(-1) during exercise (P < 0.001). Nevertheless, the expression (indicated by the mean log fluorescence) of cd11a (94 +/- 24 vs. 78 +/- 14) and cd18 (128 +/- 31 vs. 102 +/- 21) on lymphocytes and of cd11a (104 +/- 25 vs. 85 +/- 16), cd11c (497 +/- 171 vs. 408 +/- 126) cd29 (109 +/- 16 vs. 89 +/- 16), cd49 (69 +/- 8 vs. 54 +/- 11) on monocytes was decreased after exercise (all P < 0.05). In contrast, integrin expression on granulocytes was not altered by exercise. Comparison of exercising and sedentary subjects showed a significantly decreased expression of integrins in exercising subjects. Our results demonstrate that moderate exercise leads to decreased expression of integrin receptors on leucocytes. This decreased expression of adhesion molecules may result in decreased adhesion and infiltration of leucocytes into the vessel wall. This phenomenon may play a role in the beneficial effect of moderate exercise in prevention of acute and chronic vascular disease.

Adult↗
PubMed1997

Effects of exercise training and activity restriction on 6-minute walking test performance in patients with chronic heart failure.

Eighteen hospitalized patients with severe chronic heart failure (ejection fraction [mean +/- SEM] 21% +/- 1%) underwent 3 weeks of exercise training (interval bicycle ergometer and treadmill walking training exercises) and 3 weeks of activity restriction in a random-order crossover trial. Before and after exercise training and after activity restriction, a 6-minute walking test was performed to determine the maximum distance walked, hemodynamic and cardiopulmonary responses, norepinephrine levels, and ratings of leg fatigue and dyspnea while walking. A ramp test on bicycle ergometer (increments of 12.5 W/min) was performed before and after exercise training and activity restriction to determine peak oxygen uptake. After training, the maximum distance walked was increased by 65% (from 232 +/- 21 m at baseline to 382 +/- 20 m; p < 0.001), whereas after activity restriction (253 +/- 19 m) there was no significant difference compared with baseline. No significant differences in hemodynamic and cardiopulmonary parameters (with the exception of the ventilatory equivalent for carbon dioxide and perceived exertion) or norepinephrine levels were observed during walking tests. Improvement in maximum distance walked correlated significantly with training-induced increase in peak oxygen uptake measured during bicycle ergometry (r = 0.47, p < 0.05). The lower the maximum distance walked at baseline, the more pronounced the training-induced prolongation of maximum distance (r= -0.73; p < 0.001). These data support the value of exercise training in patients with severe chronic heart failure for improving maximum distance walked, as documented by the 6-minute walking test. The impairment of walking test performance during activity restriction suggests a need for long-term exercise training programs.

Activities of Daily Living↗
PubMed1997

Interval training in patients with severe chronic heart failure: analysis and recommendations for exercise procedures.

This study analyzes a new exercise training procedure, which includes interval exercise training on cycle ergometer (IntCT) (30-s work phases/60-s recovery phases) and on treadmill (60-s work and recovery phases each). Training was applied for 3 wk in 18 patients with severe chronic heart failure (CHF) ((mean +/- SEM) age 52 +/- 2 yr, ejection fraction 21 +/- 1%). Peak VO2 was increased from 12.2 +/- 0.7 to 14.6 +/- 0.7 ml-kg-1 min-1 owing to training (P < 0.001). A specific steep ramp test (work rate increments 25 W.10 s-1) was developed to derive exercise intensity for work phases in IntCT, which was 50% of the maximum work rate achieved. Steep ramp test was performed at the start of the study to determine the initial training work rate, then weekly to readjust it. Since the maximum work rate achieved from this test increased weekly (144 +/- 10 W -->172 +/- 10 W-->200 +/- 11 W; P < 0.001), the training work rate also increased (72 +/- 4 W-->86 +/- 6 W-->100 +/- 7 W; P < 0.001). Physical responses to IntCT were measured. There was no significant change in heart rate, blood pressure, and ratings of perceived exertion (RPE) using a Borg Scale between the first and the third week of training (heart rate 88 +/- 3 b.min-1; blood pressure 115 +/- 4/80 +/- 2 mm Hg; leg fatigue 12 +/- 1; dyspnea 10 +/- 1). Mean lactate concentration (1.70 +/- 0.09 mmol-1-1) indicated an overall aerobic range of training intensity. When compared with the commonly used intensity level of 75% peak VO2 from an ordinary ramp test (work rate increments 12.5 W.min-1), the performed training work rate was more than doubled (240%; P < 0.0001) while cardiac stress was lower (86%; P < 0.01). Values of norepinephrine and epinephrine as well as of RPE corresponded to those measured at 75% peak VO2. Interval exercise training is thus recommended for selected patients with CHF as it allows intense exercise stimuli on peripheral muscles with minimal cardiac strain. Using a steep ramp test, training work rate can be determined and readjusted weekly during initial training period.

Bicycling↗
PubMed1996

Effects of short-term exercise training and activity restriction on functional capacity in patients with severe chronic congestive heart failure.

Previous exercise training studies in patients with chronic congestive heart failure (CHF) were performed for periods lasting > 2 months, and effects of activity restriction on exercise induced-benefits were not systematically assessed. With one exception study, patients were not reported to be transplant candidates. In this random-order crossover study, effects of 3 weeks of exercise training and 3 weeks of activity restriction on functional capacity in 18 hospitalized patients with severe CHF [(mean +/- SEM) age 52 +/- 2 years; ejection fraction 21 +/- 1%; half of them on a transplant waiting list] were assessed. The training program consisted of interval exercise with bicycle ergometer (15 minutes) 5 times weekly, interval treadmill walking (10 minutes), and exercises (20 minutes), each 3 times weekly. With training, the onset of ventilatory threshold was delayed (p < 0.001), with increased work rate by 57% (p < 0.001) and oxygen uptake by 23.7% (p < 0.001). On average, there was a 14.6% decrease in slope of ventilation/carbon dioxide production before the onset of ventilatory threshold (p < 0.05), and ventilatory equivalent of carbon dioxide production by 10.3% (p < 0.01). At the highest comparable work rate (56 +/- 5 W) the following variables were decreased: heart rate (7.3%; p < 0.05), lactate (26.6%; p < 0.001), and ratings of perceived leg fatigue and dyspnea (14.5% and 16.5%; p < 0.001 each). At peak exercise, oxygen uptake was increased by 19.7% (p < 0.01) and oxygen pulse by 14.2% (p < 0.01). There was a correlation of baseline peak oxygen uptake and increase of peak oxygen uptake due to training (r = -0.75; p < 0.004). Independently of the random order, data after activity restriction did not differ significantly from data measured at baseline. Patients with stable, severe CHF can achieve significant improvements in aerobic and ventilatory capacity and symptomology by short-term exercise training using interval exercise methods. Impairments due to activity restriction suggest the need for long-term exercise training.

Chronic Disease↗
PubMed1996

MoMuLV proviral integrations identified by Sup-F selection in tumors from infected myc/pim bitransgenic mice correlate with activation of the gfi-1 gene.

Infecting mice with a mutant Moloney murine leukemia virus which contains the bacterial suppressor tRNA supF in its LTR allows rapid cloning of proviral integration sites from genomic tumour DNA. In a previous study Emu pim-1/Emu L-myc bitransgenic mice had been inoculated neonatally with MoMuLV supF virus. The retroviral infection led to acceleration of lymphomagenesis indicating the proviral activation of further oncogenes cooperating with myc and pim-1 in tumour development. Using a functional supF screen for analysis of genomic mouse tumour DNA libraries which had been constructed in the phage vector EMBL3A, a common proviral integration site on mouse chromosome 5 was cloned and found to be identical to the proviral integration site evi-5 which has recently been identified in an AKXD T-cell lymphoma and which is located 18 kb upstream of the gfi-1 gene. Tumours bearing evi-5 integrations showed an enhanced gfi-1 expression level suggesting that gfi-1 is the target gene for insertions at the evi-5 locus. Together with three other previously described Moloney integration clusters all responsible for enhanced gfi-1 expression the number of tumours from infected double transgenic Emu L-myc/Emu pim-1 transgenic mice with retrovirally activated gfi-1 added up to 53% underscoring the role of GFI-1 as an effective collaborator for MYC and PIM-1 in the process of lymphomagenesis.

Animals↗
PubMed1996

Determination of maximal lactate steady state response in selected sports events.

Maximal lactate steady state (MLSS) refers to the upper limit of blood lactate concentration indicating an equilibrium between lactate production and lactate elimination during constant workload. The aim of the present study was to investigate whether different levels of MLSS may explain different blood lactate concentration (BLC) levels at submaximal workload in the sports events of rowing, cycling, and speed skating. Eleven rowers (mean +/- SD, age 20.1 +/- 1.5 yr, height 188.7 +/- 6.2 cm, weight 82.7 +/- 8.0 kg), 16 cyclists and triathletes (age 23.6 +/- 3.0 yr, height 181.4 +/- 5.6 cm, weight 72.5 +/- 6.2 kg), and 6 speed skaters (age 23.3 +/- 6.6 yr, height 179.5 +/- 7.5 cm, weight 73.2 +/- 5.6 kg) performed an incremental load test to determine maximal workload and several submaximal 30-min constant workloads for MLSS measurement on a rowing ergometer, a cycle ergometer, and on a speed-skating track. Maximal workload was higher (P < or = 0.05) in rowing (416.8 +/- 46.2 W) than in cling (358.6 +/- 34.4 W) and speed skating (383.5 +/- 40.9 W). The level of MLSS differed (P < or = 0.001) in rowing (3.1 +/- 0.5 mmol.l-1), cycling (5.4 +/- 1.0 mmol.l-1), and in speed skating (6.6 +/- 0.9 mmol.l-1). MLSS workload was higher (P < or = 0.05) in rowing (316.2 +/- 29.9 W) and speed skating (300.5 +/- 43.8 W) than in cycling (257.8 +/- 34.6 W). No differences (P > 0.05) in MLSS workload were found between speed skating and rowing. MLSS workload intensity as related to maximal workload was independent (P > 0.05) of the sports event: 76.2% +/- 5.7% in rowing, 71.8% +/- 4.1% in cycling, and 78.1% +/- 4.4% in speed skating. Changes in MLSS do not respond with MLSS workload, the MLSS workload intensity, or with the metabolic profile of the sports event. The observed differences in MLSS and MLSS workload may correspond to the sport-specific mass of working muscle.

Adult↗
PubMed1996

Influence of different exercise protocols on functional capacity and symptoms in patients with chronic heart failure.

This study compares hemodynamic, metabolic, and gas exchange responses, catecholamine levels, and symptoms in 35 male patients with chronic heart failure (CHF) ([mean +/- SD] age 53 +/- 11 yr; ejection fraction 24 +/- 11%) during three differently graded exercise test protocols. On three consecutive days patients performed cycle ergometry supine, with prolonged steps (prol BE) and right heart catheterization, ramplike cycle ergometry sitting (ramp BE), and ramplike treadmill walking (TMW). As in routine clinical practice, the prol BE was terminated when pathologic central hemodynamics and/or increased symptomology occurred, and ramp BE and TMW due to increased symptomology and/or physician's decision. During prol BE at ventilatory threshold (VT) the VO2 (8.6 +/- 1.8 ml.kg-1.min-1) was lower than during ramp BE (9.3 +/- 2.1 ml.kg-1.min-1) (P < 0.017) and TMW (11.8 +/- 2.3 ml.kg-1.min-1) (P < 0.0001). Prol BE, ramp BE, and TMW also differed significantly with respect to ventilation (22 +/- 7 l.min-1; 26 +/- 6 l/min-1; 29 +/- 7 l.min-1; P < 0.01) and heart rate (100 +/- 15 beats.min-1; 103 +/- 18 beats.min-1; 110 +/- 16 beats.min-1; P < 0.017). No differences were found in lactate levels, catecholamine levels, and ratings of leg fatigue and dyspnea. At test termination, the peak VO2 during prol BE (100.8 +/- 3.3 ml.kg-1.min-1) was lower than during ramp BE (13.3 +/- 4.1 ml.kg-1.min-1) (P < 0.0001) and TMW (14.7 +/- 3.4 ml.kg-1.min-1) (P < 0.0001). Peak norepinephrine value during ramp BE (4.531 +/- 2.788 nmol.l-1) was higher than during prol BE (3.707 +/- 2.262 nmol.l-1) (P < 0.001). Among the three tests, no significant differences were found for peak values of heart rate, lactate, and ratings of dyspnea. Although the VO2.kg-1 at VT was significantly higher during ramp BE and TMW compared to prol BE (P < 0.001), the values expressed as a percent of peak VO2.kg-1 were significantly lower (70 +/- 4%; 72 +/- 6%; 79 +/- 3%; P < 0.017). A systematic effect on aerobic capacity with reduced peak values during ramp BE and TMW was demonstrated when test termination was based primarily on pathological findings of central hemodynamics from prol BE.

Adolescent↗
PubMed1996

Maximal lactate steady state during the second decade of age.

Maximal lactate steady state (MLSS) presumably corresponds to the highest constant workload that can be performed by oxidative metabolism. The anaerobic and, to a minor extent, the oxidative metabolism have been reported to be affected by age. The second decade of life is the key period in the change in energy metabolism between children and adults. The aim of this study was to evaluate the effects of age on MLSS in 34 male subjects (age: 15.4 +/- 2.8 yr, range: 11-20 yr; height: 171.8 +/- 14.9 cm, range: 134-191 cm; body mass: 59.6 +/- 15.5 kg, range: 27-90 kg) performing an incremental load test to determine maximal workload and several constant load tests for MLSS measurement on a cycle ergometer. MLSS (4.2 +/- 0.7 mmol.l-1, range: 2.8 to 5.5 mmol.l-1) and MLSS intensity related to maximal workload (66.5 +/- 7.7%, range: 50-84%) were independent of age. MLSS heart rate (180.1 +/- 10.1 min-1, range: 156-208 min-1) decreased (P < 0.01) with increasing age, whereas absolute (157.2 +/- 54.8 W, range: 65-240 W) and relative MLSS workload (2.6 +/- 0.5 W.kg-1, range: 1.5 to 4.1 W.kg-1) and absolute (236.9 +/- 79.0 W, range: 100-350 W) and relative maximal workload (3.9 +/- 0.6 W.kg-1, range: 2.7 to 5.5 W.kg-1) increased (P < 0.001) with age. The age independence of MLSS supports the theory that neuromuscular factors may contribute to the frequently observed changes in response to given exercise with physical maturity more than changes in oxidative metabolism and/or glycolysis.

Adolescent↗
PubMed1995

Survival and death of prelymphomatous B-cells from N-myc/bcl-2 double transgenic mice correlates with the regulation of intracellular Ca2+ fluxes.

Coexpression of the proto-oncogenes c-myc and bcl-2 under the control of the immunoglobulin enhancer E mu provokes the rapid development of primitive lymphoid tumors in transgenic mice. In the present study we show that the myc family members N-myc and L-myc also cooperate with bcl-2 in oncogenesis and can provoke the development of more mature pre-B, B and T cell type lymphomas. The analysis of prelymphomatous B-cells from single E mu N-myc and bcl-2-Ig transgenic animals and from young, tumor free, double transgenic E mu N-myc/bcl-2-Ig mice revealed that E mu directed expression of N-myc leads to very rapid apoptosis after explantation and culturing compared to B-cells from normal mice. As expected, B-cells from bcl-2-Ig transgenics were protected to a certain degree from apoptosis. Strikingly however, B-cells from E mu N-myc/bcl-2-Ig double transgenic animals were found to be almost completely resistant towards a number of different apoptotic stimuli. Furthermore, after treatment with H2O2, which can trigger apoptosis, B-cells from E mu N-myc animals reach levels of intracellular free Ca2+ concentrations that are comparable to B-cells from normal mice, whereas B-cells from bcl-2-Ig or E mu N-myc/bcl-2-Ig double transgenic mice show no increase in intracellular Ca2+ concentrations after stimulation with H2O2. These findings suggest that the prevention of apoptosis conferred by bcl-2 correlates with the inhibition of intracellular Ca2+ fluxes whereas induction of apoptosis mediated by N-myc requires normal Ca2+ levels. We hypothesize therefore that the regulation of intracellular Ca2+ concentrations represent one important parameter in the oncogenic cooperation between bcl-2 and N-myc.

Animals↗
PubMed1995

Anaerobic threshold, individual anaerobic threshold, and maximal lactate steady state in rowing.

Anaerobic threshold, also termed 4.0 mmol.l-1 threshold (AT4), and individual anaerobic threshold (IAT), presumably indicate the workload corresponding to maximal lactate steady state (MLSS) during an incremental workload test. MLSS is the highest blood lactate concentration (BLC) resulting in a steady state during constant workload. The purpose of the present investigation was to ascertain the validity of AT4 and IAT as related to MLSS during rowing ergometry. Nine rowers (mean +/- SD age 20.2 +/- 1.6 yr; HT 187.2 +/- 4.9 cm; WT 81.1 +/- 6.3 kg) performed an incremental load test to determine AT4, IAT and maximal workload and several 30 min constant workloads for MLSS measurement on a mechanical rowing ergometer. The incremental load test was conducted at 215 W and increased by 35 W every 3.0 min. The first 30 min constant workload was conducted at 60% of maximal workload (363.3 +/- 45.1 W). If a constant load test resulted in a steady state of BLC subsequent constant load tests were performed and workload increased by 3% to 10% after each constant load test until no steady state of BLC could be observed. AT4 (287.0 +/- 20.5 W), IAT (287.1 +/- 25.1 W), and BLC at IAT (4.2 +/- 0.8 mmol.l-1) were higher (P < 0.001) compared to MLSS workload (255.1 +/- 17.5 W) and MLSS (3.0 +/- 0.6 mmol.l-1), respectively. Independent of the practical application of AT4 and IAT, in rowing AT4 and IAT do not represent MLSS workload.

Anaerobic Threshold↗
PubMed1993

[Quantitative 201Tl-scintigraphy of the lower limb in arterial occlusive disease].

201Tl scintigraphy is useful in evaluating the hemodynamic consequences of arterial stenoses in arterial occlusive disease. The aim of the present study was to determine normal values for absolute Tl uptake in the lower leg, for the quotient between left and right lower leg uptake as well as for the redistribution pattern after bicycle exercise. We examined as reference 49 patients without clinical evidence of peripheral or coronary artery disease: absolute Tl uptake in the lower leg in anterior scintigraphy (acquisition time: 120 sec) was 5.02 +/- 1.70 counts/pixel (left) and 5.21 +/- 1.53 counts/pixel (right), the quotient between right and left lower leg was 0.85 +/- 0.09 and the redistribution pattern (quotient of the mean activity exercise/rest) 0.82 +/- 0.17 (left) and 0.83 +/- 0.15 (right). The arithmetic mean minus 2 standard deviations was regarded as the lower limit of normal. In 8 patients with mechanical compression of the left femoral artery before injection at least two scintigraphic parameters were abnormal, in 7 patients with angiographically proven peripheral artery disease at least one scintigraphic parameter was below normal. Quantification of Tl redistribution offers diagnostic advantages in bilateral peripheral artery disease.

Adult↗
PubMed1991

Muscle cross-section measurement by magnetic resonance imaging.

Muscle cross-section areas were measured by magnetic resonance imaging (MRI) in the thigh of a human cadaver, the results being compared with those obtained by photography of corresponding anatomic macroslices. A close correlation was found between MRI and photographic evaluation, differences between the methods ranging from nil to 9.5%, depending on the scan position and the muscle groups. In vivo MRI measurements were performed on 12 female and 16 male students, the objectivity, the test-retest reliability and the variability of the MRI measurements being studied by fixing the scan position either manually or by coronary scan. The latter method appeared to be more objective and reliable. The coefficients of variation for muscle cross-section areas measured by MRI were in the range of those for the planimetry of given cross-section areas. Allowing for differentiation between several small muscle bundles in a given area, MRI proved to be a suitable method to quantify muscle cross-sections for intra- and interindividual analysis of muscle size.

Adult↗