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J Lonsdorfer

Publications and source records attributed to J Lonsdorfer.

At least 19 recordsLinked to original sources
PubMed2006

Chronic L-arginine supplementation enhances endurance exercise tolerance in heart failure patients.

The purpose of the study was to determine the potential beneficial effect of six weeks oral L-arginine supplementation (LAS) on endurance exercise, an important determinant of daily-life activity in patients with chronic stable heart failure (CHF). After an initial incremental maximal exercise test, CHF patients performed an identical thirty-minute interval endurance exercise test before and after six weeks with (L-arginine group; ARG) or without LAS (control group; CTL). Hemodynamic, respiratory, and metabolic parameters were determined at rest, during exercise, and during recovery. Mean heart rate decreased throughout exercise and recovery after LAS (- 8.2 +/- 1.4 b x min(-1); p = 0.003 and - 6.7 +/- 1.6 b x min(-1); p < 0.001, respectively), systemic blood pressure and respiratory parameters remaining unchanged. Resting L-argininaemia increased from 102 +/- 11 to 181 +/- 37 micromol x l(-1) (p < 0.004) and exercise-induced peak increase in plasma lactate was blunted after LAS (4.13 +/- 0.75 vs. 3.13 +/- 0.39 mmol x l(-1); p = 0.02). No significant change was observed in the control group. In heart failure patients, six weeks oral LAS enhances endurance exercise tolerance, reducing both heart rate and circulating lactates. This suggests that chronic LAS might be useful as a therapeutic adjuvant in order to improve the patient's physical fitness.

Administration, Oral↗
PubMed2003

Effects of a wheelchair ergometer training programme on spinal cord-injured persons.

STUDY DESIGN: Before and after investigation of the effects of a wheelchair ergometer Training programme. OBJECTIVE: To investigate the effects of an original interval-training programme on work capacity and cardiorespiratory variables with spinal cord-injured persons (SCIP's) on a wheelchair-specific ergometer. SETTING: BESANCON, FRANCE. METHODS: Seven SCIP's (male) performed 45 min of wheelchair ergometry three times per week, for 6 weeks. Training effects on maximal dynamic performance and endurance capacity were studied by comparison of performance and cardiorespiratory responses observed during both a maximal progressive test (10 W/2 min) and the same training session performed before and after training. RESULTS: Training induced significant improvements in maximal tolerated power (+19.6%), in peak oxygen consumption (VO2,+16%), and in oxygen pulse (O2p,+18.7%). At ventilatory threshold, significant improvements were also observed in power output (+63%), VO2VT(+ 34.1), ventilation VEVT(+ 37.1%), and V2pVT(+ 19.9% ). Heart rate and ventilation were significantly lower (-11 and -14.6%, respectively) after training at the same work rate, while VO2 was unchanged. Between the first and the last training session, the total physical work was improved by 24.7%, whereas heart rate was unchanged. CONCLUSION: An interval-training programme individualised to each paraplegic subject using a wheelchair ergometer can significantly improve the fitness level and endurance capacity.

Adult↗
PubMed2002

L-arginine reduces exercise-induced increase in plasma lactate and ammonia.

To investigate the effect of L-arginine supplementation (L-ARG) on physiological and metabolic changes during exercise, we determined in a double-blind study the cardiorespiratory (heart rate, oxygen consumption (VO(2)) and carbon dioxide production (VCO(2)) and the metabolic (lactate and ammonia) responses to maximal exercise after either an intravenous L-ARG hydrochloride salt or placebo load in 8 healthy subjects. Exercise-induced increases in heart rate, VO(2) and VCO(2) were not significantly different after L-ARG or placebo. By contrast, peak plasma ammonia and lactate were significantly decreased after L-ARG load (60.6 +/- 8.2 vs. 73.1 +/- 9.1 micro mol x l(-1), p < 0.01 and 7.1 +/- 0.7 vs. 8.2 +/- 1.1 mmol x l(-1), p < 0.01, for ammonia and lactate, respectively). Plasma L-citrulline increased significantly during exercise only after L-ARG load, despite a concomitant decrease in plasma L-ARG. Furthermore, a significant inverse relationship was observed between changes in lactate and L-citrulline concentrations after L-ARG load (r = -0.84, p = 0.009). These results demonstrate that intravenous L-ARG reduces significantly exercise-induced increase in plasma lactate and ammonia. Taken together, the specific L-citrulline increase and the inverse relationship observed between L-citrulline and plasma lactate after L-ARG might support that L-ARG supplementation enhances the L-arginine-nitric oxide (NO) pathway during exercise.

Adult↗
PubMed2001

Non-invasive cardiac output evaluation during a maximal progressive exercise test, using a new impedance cardiograph device.

One of the greatest challenges in exercise physiology is to develop a valid, reliable, non-invasive and affordable measurement of cardiac output (CO). The purpose of this study was to evaluate the reproducibility and accuracy of a new impedance cardiograph device, the Physio Flow, during a 1-min step incremental exercise test from rest to maximal peak effort. A group of 12 subjects was evaluated to determine the reproducibility of the method as follows: (1) each subject performed two comparable tests while their CO was measured by impedance cardiography using the new device (COImp1, COImp2), and (2) in a subgroup of 7 subjects CO was also determined by the direct Fick method (COFick) during the second test. The mean difference between the values obtained by impedance (i.e. COImp1-COImp2) was -0.009 l.min-1 (95% confidence interval: -4.2 l.min-1, 4.2 l.min-1), and CO ranged from 3.55 l.min-1 to 26.75 l.min-1 (n = 146). When expressed as a percentage, the difference (COImp1-COImp2) did not vary with increasing CO. The correlation coefficient between the values of COImp and COFick obtained during the second exercise test was r = 0.94 (P < 0.01, n = 50). The mean difference expressed as percentage was -2.78% (95% confidence interval: -27.44%, 21.78%). We conclude that COImp provides a clinically acceptable evaluation of CO in healthy subjects during an incremental exercise.

Adult↗
PubMed2001

Oxidative capacity of skeletal muscle in heart failure patients versus sedentary or active control subjects.

OBJECTIVES: We investigated the in situ properties of muscle mitochondria using the skinned fiber technique in patients with chronic heart failure (CHF) and sedentary (SED) and more active (ACT) controls to determine: 1) whether respiration of muscle tissue in the SED and ACT groups correlates with peak oxygen consumption (pVO(2)), 2) whether it is altered in CHF, and 3) whether this results from deconditioning or CHF-specific myopathy. BACKGROUND: Skeletal muscle oxidative capacity is thought to partly determine the exercise capacity in humans and its decrease to participate in exercise limitation in CHF. METHODS: M. Vastus lateralis biopsies were obtained from 11 SED group members, 10 ACT group members and 15 patients with CHF at the time of transplantation, saponine-skinned and placed in an oxygraphic chamber to measure basal and maximal adenosine diphosphate (ADP)-stimulated (V(max)) respiration rates and to assess mitochondrial regulation by ADP. All patients received angiotensin-converting enzyme (ACE) inhibitors. RESULTS: The pVO(2) differed in the order CHF < SED < ACT. Compared with SED, muscle alterations in CHF appeared as decreased citrate synthase, creatine kinase and lactate dehydrogenase, whereas the myosin heavy chain profile remained unchanged. However, muscle oxidative capacity (V(max), CHF: 3.53 +/- 0.38; SED: 3.17 +/- 0.48; ACT: 7.47 +/- 0.73, micromol O(2).min(-1).g(-1)dw, p < 0.001 vs. CHF and SED) and regulation were identical in patients in the CHF and SED groups, differing in the ACT group only. In patients with CHF, the correlation between pVO(2) and muscle oxidative capacity observed in controls was displaced toward lower pVO(2) values. CONCLUSIONS: In these patients, the disease-specific muscle metabolic impairments derive mostly from extramitochondrial mechanisms that disrupt the normal symmorphosis relations. The possible roles of ACE inhibitors and level of activity are discussed.

Citrate (si)-Synthase↗
PubMed2001

Effect of cyclosporin A and its vehicle on cardiac and skeletal muscle mitochondria: relationship to efficacy of the respiratory chain.

Although cyclosporin (CsA) is considered to be the best immunosuppressive molecule in transplantation, it has been suspected to alter mitochondrial respiration of various tissues. We evaluated the acute effect of CsA and its vehicle on maximal oxidative capacity (V(max)) of cardiac, soleus and gastrocnemius muscles of rats by an oxygraphic method in saponin skinned muscle fibres. The effects of Sandimmun (a formulation of CsA), vehicle of Sandimmun (cremophor and ethanol (EtOH)), CsA in EtOH and EtOH alone were tested. Increasing concentrations (5 - 20 - 50 - 100 microM) of CsA (or vehicles) were used. Sandimmun profoundly altered the V(max) of all muscles. For example, at 20 microM, inhibition reached 18+/-3, 23+/-5, 45+/-5%, for heart, soleus and gastrocnemius respectively. There were only minor effects of CsA diluted in EtOH and EtOH alone on V(max) of cardiac muscle. Because the effects of vehicle on V(max) were similar or higher than those of Sandimmun, the inhibition of oxidative capacity could be entirely attributed to the vehicle for all muscles. Next, we investigated the potential sites of action of the vehicle on the different complexes of the mitochondrial respiratory chain by using specific substrates and inhibitors. The vehicle affected mitochondrial respiration mainly at the level of complex I ( approximately -85% in skeletal muscles, and -32% in heart), but also at complex IV ( approximately -26% for all muscles). The mechanism of action of the vehicle on the mitochondrial membrane and the implications for the clinical use of immunosuppressive drugs are discussed.

Adenosine Diphosphate↗
PubMed2001

Interval training program on a wheelchair ergometer for paraplegic subjects.

BACKGROUND: Various combinations of training intensity, duration and frequency are often proposed to people with spinal cord injuries in order to improve their fitness. However, no consensus about a specific training program has been reached for such a population. OBJECTIVE: This study investigated the effects of a short interval training program specifically designed for patients with spinal cord injuries. METHODS: Paraplegic men performed 30-min wheelchair ergometry three times per week, for 4 weeks. Maximal dynamic performance and endurance capacity were studied before and after the training program with an incremental test (10 W/2 min) until volitional fatigue and a constant work rate test, respectively. Cardiorespiratory responses were continuously studied during each of these tests. RESULTS: Training induced significant improvement in maximal tolerated power (+27.9%), and in peak oxygen consumption ([VO2, +18.5%). After training the subjects were able to maintain the load applied during the constant test (total mechanical work +210.7%), for a significantly longer time. The heart rate, [VO2 and ventilation values observed when the volunteers ended their first constant load test were significantly higher (+10%, +10%, +40% respectively) than those obtained after a similar time period during the second constant load test which was performed after the training program. CONCLUSION: After this short training period, with an appropriate combination of different types of training, duration, intensity and frequency exercises, we observed a significant improvement in the fitness level and endurance capacity of paraplegic subjects.

Adult↗
PubMed2001

Exercise training with a heart device: a hemodynamic, metabolic, and hormonal study.

PURPOSE: The mechanisms of the training-induced improvements in left ventricular assist (LVAD) patients are unknown. METHODS: We measured the hemodynamic, gas exchange, and metabolic and hormonal effects of 6-wk exercise training in a cardiogenic shock patient who was assisted by an LVAD. RESULTS: After training, the peak power and VO2 increased by 166% and 56%, respectively (80 W and 16.1 mL x min(-1) x kg(-1)), whereas the ventilatory drive decreased. Although the LVAD output increased little with exercise, the systemic cardiac output rose (adequately for the VO2) from 5.91 and 4.90 L x min(-1) at rest to 9.75 and 9.47 L x min(-1) at peak work rate, before and after training, respectively. Thus, the left ventricle ejected again through the aortic valve. Unloading and/or retraining resulted in a left ventricular filling pressure decrease. Although the right ventricular ejection fraction increased with exercise, it decreased again at the maximal load after training. For a given work rate the arterial lactate, the norepinephrine (NE) and epinephrine (E) concentrations fell after training, but the enhanced maximal work rate elicited higher NE and E concentrations (4396 and 1848 pg x mL(-1), respectively). The lack of right ventricular unloading might have kept the atrial natriuretic peptide higher after training, but the blood cyclic GMP and endothelin were lower after training. CONCLUSION: In an LVAD patient, retraining returns the exercise capacity to the class III level by peripheral and left ventricular hemodynamic improvements, but the safety of maximal exercise remains to be proven in terms of right ventricular function and orthosympathetic drive.

Cardiomyopathies↗
PubMed2000

Interrupter technique versus plethysmography for measurement of respiratory resistance in children with asthma or cystic fibrosis.

The purpose of the present study was to compare measurements of respiratory system resistance by the interrupter method (Rrsint) with those of airway resistance by plethysmography (Raw) in nonobstructed children with asthma or cystic fibrosis (ratio of forced expiratory volume in 1 sec to vital capacity, FEV(1)/VC >/=80% with a forced expiratory flow rate between 25-75% of forced vital capacity, FEF(25-75) >/=75% of normal values) and in obstructed children with the same diseases (FEV(1)/VC <80% and/or FEF(25-75) <75% of normal values). Eighty-one children (47 asthmatics and 34 suffering from cystic fibrosis) aged 5-18 years (mean 11.2 +/- SD 3.4 years) were included in the study. For the overall group, we observed generally lower values for Raw (4.7 +/- 2. 8 cmH(2)O.L(-).s) than for Rrsint20 (extrapolation of the mouth pressure during occlusion to 40 ms after interruption) (5.6 +/- 1.7 cmH(2)O.L(-1).s) (P < 0.02), or for Rrsint40 (extrapolation of the mouth pressure during occlusion to 60 ms after interruption) (6.6 +/- 2.2 cmH(2)O.L(-1).s) (P < 0.001), but there was no difference between Rrsint20 and Raw in the obstructed subgroup. Moreover, we observed a correlation between the difference (Rrsint20 - Raw) expressed in percentage of predicted values and the degree of obstruction estimated by FEV(1)/VC (r = 0.56, P < 0.001). The differences between the specific resistances (sRrsint20 - sRaw, sRrsint40 - sRaw) were also correlated with the severity of the obstruction (r = 0.65, P < 0.001 and r = 0.57, P < 0.001, respectively). We observed also that the tendency to underestimate resistance by Rrsint in obstructed children was not the same in children with asthma and cystic fibrosis. We conclude that the tendency of Rrsint, as measured with our method, to underestimate airway obstruction appears to increase in proportion to the severity of the airway obstruction.

Adolescent↗
PubMed2000

Immunosuppressive treatment affects cardiac and skeletal muscle mitochondria by the toxic effect of vehicle.

In order to examine whether immunosuppressive treatment could be responsible for the reduced exercise capacity of heart transplant recipients (HTR), we studied the effects of long-term immunosuppressive treatment with cyclosporin A (CsA) and its vehicle (2/3 cremophor and 1/3 alcohol diluted in olive oil) on in situ mitochondrial respiration of different muscles. Rats were fed for 3 weeks with 10 or 25 mg/kg/day CsA in its vehicle (CsA10 and CsA25 groups), or vehicle or H(2)O. Oxygen consumption rate was measured in saponin skinned fibers without (V(0)) and with ADP until maximal respiration (V(max)) was reached and K(M)for ADP as well as V(max)were calculated using non-linear fit of the Michaelis-Menten equation. In the cardiac muscle of the CsA25 group, V(0)and V(max)were decreased by immunosuppressive treatment respectively from 6.33+/-0.51 to 3.18+/-0.3micromol O(2)/min/g dw (P<0.001) and from 29.0+/-1.5 to 18.1+/-1.6micromol O(2)/min/g dw (P<0.001), an effect which could be entirely attributed to the vehicle itself, with no difference between CsA10 and CsA25. Regulation of cardiac mitochondrial respiration by ADP was altered by vehicle with the K(M)for ADP decreasing from 371+/-37 to 180+/-21microm(P<0.001). A similar trend was observed in the diaphragm or soleus, although to a lesser extent. In contrast, V(0)and V(max)decreased in glycolytic gastrocnemius muscle respectively from 1.7+/-0.2 to 0.94+/-0.14 (P<0. 01) and from 6.8+/-0.3 to 5.1+/-0.4micromol O(2)/min/g dw (P<0.001) in the CsA25 group, but the main effects could be attributed to CsA itself. It was concluded that immunosuppressive treatment induces a deleterious effect on cardiac and skeletal muscle oxidative capacities, mainly due to cremophor, the main component of vehicle.

Adenosine Diphosphate↗
PubMed2000

A new impedance cardiograph device for the non-invasive evaluation of cardiac output at rest and during exercise: comparison with the "direct" Fick method.

The objectives of this study were to evaluate the reliability and accuracy of a new impedance cardiograph device, the Physio Flow, at rest and during a steady-state dynamic leg exercise (work intensity ranging from 10 to 50 W) performed in the supine position. We compared cardiac output determined simultaneously by two methods, the Physio Flow (QcPF) and the direct Fick (QcFick) methods. Forty patients referred for right cardiac catheterisation, 14 with sleep apnoea syndrome and 26 with chronic obstructive pulmonary disease, took part in this study. The subjects' oxygen consumption values ranged from 0.14 to 1.19 l x min(-1). The mean difference between the two methods (QcFick - QcPF) was 0.04 l x min(-1) at rest and 0.29 l x min(-1) during exercise. The limits of agreement, defined as mean difference +/- 2SD, were -1.34, +1.41 l x min(-1)] at rest and -2.34, +2.92 l x min(-1) during exercise. The difference between the two methods exceeded 20% in only 2.5% of the cases at rest, and 9.3% of the cases during exercise. Thoracic hyperinflation did not alter QcPF. We conclude that the Physio Flow provides a clinically acceptable and non-invasive evaluation of cardiac output under these conditions. This new impedance cardiograph device deserves further study using other populations and situations.

Aged↗
PubMed2000

Lack of acute cyclosporine nephrotoxicity in late heart-transplant recipients.

BACKGROUND: Cyclosporine induces daily renal hypoperfusion in subjects with normal atrial natriuretic peptide (ANP) levels, but its acute effects in heart transplant patients with increased ANP remain to be determined. METHODS: Cyclosporinemia and creatinine clearance were monitored during 7 hours following cyclosporine administration in 6 heart transplant patients. RESULTS CONCLUSIONS: No acute cyclosporine-induced decrease in creatinine clearance was observed after heart transplantation. These data suggest that maintenance cyclosporine dose may be less nephrotoxic than suspected and that increased ANP might protect the renal function late after heart transplantation.

Acute Disease↗
PubMed2000

Cardiorespiratory and metabolic responses to exercise in HbSC sickle cell patients.

PURPOSE: Relative to healthy control individuals with normal hemoglobin (Hb), patients carrying the double heterozygous form of sickle cell disease (HbSC) display an impaired oxygen transport capacity. The present study was undertaken to determine the influence of the decreased oxygen availability associated with the presence of HbSC on the cardiorespiratory and metabolic responses to endurance exercise. METHODS: Eleven black men affected by the double heterozygous form of the sickle cell disease (HbSC group) and seven healthy subjects with normal Hb (HbAA group) of the same ethnic origin submitted successively to an incremental exercise test to exhaustion on a cycle ergometer for the determination of their maximal tolerated power and to a 20-min endurance exercise. RESULTS: The HbSC had a significantly lower exercise tolerance than the HbAA. During the endurance exercise, they exhibited furthermore significantly lower VO2, VCO2, and minute ventilation V(E) than the HbAA. Despite the fact that the HbSC exercised at a significantly lower mean absolute work rate than the HbAA, except for the ventilatory equivalent for CO2 (V(E)/VCO2), which was higher (P < 0.001) in the HbSC group, the other parameters recorded during the 20-min endurance exercise (heart rate, arterial PaO2, PaCO2, pH, lactate, and VE/VO2, the ventilatory equivalent for O2) and during the subsequent recovery (blood lactate) were similar for both groups. CONCLUSION: The study underscores the importance of considering relative work rate as well as absolute work rate to arrive at a correct interpretation of exercise and recovery data. The results give evidence that the modifications of homeostasis brought into play by exercise were shifted toward distinctly lower absolute work rates in HbSC patients.

Adult↗
PubMed2000

VO(2) kinetics reveal a central limitation at the onset of subthreshold exercise in heart transplant recipients.

Because the cardiocirculatory response of heart transplant recipients (HTR) to exercise is delayed, we hypothesized that their O(2) uptake (VO(2)) kinetics at the onset of subthreshold exercise are slowed because of an impaired early "cardiodynamic" phase 1, rather than an abnormal subsequent "metabolic" phase 2. Thus we compared the VO(2) kinetics in 10 HTR submitted to six identical 10-min square-wave exercises set at 75% (36 +/- 5 W) of the load at their ventilatory threshold (VT) to those of 10 controls (C) similarly exercising at the same absolute (40 W; C40W group) and relative load (67 +/- 14 W; C67W group). Time-averaged heart rate, breath-by-breath VO(2), and O(2) pulse (O(2)p) data yielded monoexponential time constants of the VO(2) (s) and O(2)p increase. Separating phase 1 and 2 data permitted assessment of the phase 1 duration and phase 2 VO(2) time constant (). The VO(2) time constant was higher in HTR (38.4 +/- 7.5) than in C40W (22.9 +/- 9.6; P < or = 0. 002) or C67W (30.8 +/- 8.2; P < or = 0.05), as was the O(2)p time constant, resulting from a lower phase 1 VO(2) increase (287 +/- 59 vs. 349 +/- 66 ml/min; P < or = 0.05), O(2)p increase (2.8 +/- 0.6 vs. 3.6 +/- 1.0 ml/beat; P < or = 0.0001), and a longer phase 1 duration (36.7 +/- 12.3 vs. 26.8 +/- 6.0 s; P < or = 0.05), whereas the was similar in HTR and C (31.4 +/- 9.6 vs. 29.9 +/- 5.6 s; P = 0.85). Thus the HTR have slower subthreshold VO(2) kinetics due to an abnormal phase 1, suggesting that the heart is unable to increase its output abruptly when exercise begins. We expected a faster in HTR because of their prolonged phase 1 duration. Because this was not the case, their muscular metabolism may also be impaired at the onset of subthreshold exercise.

Adult↗
PubMed2000

Exercise-induced increase in circulating adrenomedullin is related to mean blood pressure in heart transplant recipients.

Adrenomedullin (ADM) is a newly discovered potent vasorelaxing and natriuretic peptide that recently has been shown to be increased after heart transplantation. To investigate the hemodynamic factors modulating its release and the eventual role of ADM in blood pressure regulation after heart transplantation, seven matched heart-transplant recipients (Htx) and seven normal subjects performed a maximal bicycle exercise test while monitoring for heart rate, blood pressure, and circulating ADM. Baseline heart rate and systemic blood pressure were higher in Htx; left ventricular mass index and ADM tended to be higher after heart transplantation and correlated positively in Htx (r = 0.79, P = 0.03). As expected, exercise-induced increase in heart rate was lower in Htx than in controls (60 +/- 11 % vs. 121 +/- 14 %, respectively) and blood pressure increase was similar in both groups. Maximal exercise increased significantly plasma ADM in both groups (from 25.3 +/- 3.1 to 30.7 +/- 3.5 pmol/L, P < 0.05 and from 15.2 +/- 1.4 to 29.1 +/- 4.4 pmol/L, P = 0.02 in Htx and controls, respectively), the hypotensive peptide level remaining elevated until the 30th min of recovery. A significant inverse relationship was observed between peak mean blood pressure and circulating ADM in Htx (r = -0.86, P < 0.02). Besides showing that circulating ADM is increased after heart transplantation, the present study demonstrates a positive relationship between baseline ADM and left ventricular mass index. Furthermore, maximal exercise-induced increase in ADM is inversely related to mean blood pressure in Htx, suggesting that ADM might participate in blood pressure regulation during exercise after heart transplantation.

Adrenomedullin↗