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Biomedical subjects

André Denjean

Publications and source records attributed to André Denjean.

15 recordsLinked to original sources
PubMed2006

Echocardiographic right ventricular strain analysis in chronic heart failure.

OBJECTIVE: We sought to compare the additive value of right ventricular (RV) function assessed by longitudinal systolic strain (epsilon% - ROI: 9.2 at 10.8 mm) with cardiopulmonary exercise testing (CPET) or brain natriuretic peptide (BNP) in patients with heart failure (HF). METHOD: We studied 19-patients (age = 56 +/- 8 years) in New York Heart Association HF class III-IV, who underwent standard and tissue Doppler echocardiography, CPET and BNP measurements on the same day. RV function was assessed by systolic strain (epsilon, %, ROI: 9.2-10.8 mm) in the mid-segment. Clinical outcomes were examined at 6 months. RESULTS: epsilon (-19.9+/-6.8%) was correlated with BNP (R = 0.52, P = 0.02), slope VE/VCO(2) (R = -0.65, P = 0.003), peak VO(2) (R = 0.46, P = 0.04) and the maximal workload (Watts) developed during CPET (R = 0.54, P=0.02). During follow-up, 1-patient died, 1-underwent heart transplantation, and 4 were re-hospitalized for worsening HF. Patients with major adverse cardiac events (MACE) had a significantly higher mean BNP concentration (852.8 ng/mL +/- 1114.3 vs. 201.4+ /- 293.8, P = 0.03), higher VE/VCO(2) (41.3 +/- 3.6 vs. 35.0 +/- 4.8 P < 0.001) and lower epsilon (-13.9 +/- 4.9 vs. -22.2+ /- 5.8, P < 0.001) than patients who remained MACE-free. By multivariate analysis, ST was the only predictor of MACE. CONCLUSION: In HF-patients presenting, RV-function assessed by systolic epsilon was reliable, easily measurable and a stronger prognosticator than CPET or BNP.

Chronic Disease↗
PubMed2006

A distributional analysis of the effect of physical exercise on a choice reaction time task.

The aim of this study was to examine the facilitating effects of physical exercise on the reaction process. Eleven participants with specific expertise in decision-making sports performed a choice reaction time task during moderate sub-maximal exercise (90% of their ventilatory threshold power). Participants were tested at rest and while cycling. During exercise, the participants were faster, without being more variable. We suggest that the effect of exercise on cognitive performance was due to a major generalized improvement of the whole distribution of response time and, although the benefit effect was small, it was consistent throughout the entire range of reaction times.

Adult↗
PubMed2005

Spectral analysis of heart rate variability: interchangeability between autoregressive analysis and fast Fourier transform.

Interchangeability between fast Fourier transform (FFT) and autoregressive (AR) analysis was assessed on series of 256 R-R intervals recorded in 56 seated subjects and in 15 men performing an orthostatic test. Low- (LF) and high-frequency (HF) components were calculated and expressed both in absolute (square milliseconds) and normalized units (NU). During orthostatic stress, the same upward trend for LF square milliseconds and LF/HF ratio and downward trend for HF square milliseconds and HF NU were observed with FFT and AR analysis. However, the values for HF square milliseconds were significantly greater with FFT, as compared with AR analysis in standing position (P < .05). Moreover, Bland & Altman method highlighted a large discrepancy between the results of FFT and AR analysis for all heart rate variability indices in the 3 conditions. Therefore, parametric and nonparametric spectral analyses could not be considered as interchangeable at rest in healthy subjects even if they give same qualitative results.

Adolescent↗
PubMed2005

Effect of Nomega-nitro-L-arginine methyl ester-induced intrauterine growth restriction on postnatal lung growth in rats.

Infants with intrauterine growth restriction (IUGR) are at high risk for morbidity and mortality. Preeclampsia, one of the leading causes of IUGR, begins during the canalicular phase of lung development. The aim of our study was to determine whether induced IUGR was responsible for abnormal lung development in rat pups. We randomized pregnant Sprague-Dawley rats to daily gavage with either the nitric oxide synthase inhibitor Nomega-nitro-L-arginine methyl ester (L-NAME; n = 5, 50 mg . kg(-1) . d(-1)) or pure water (n = 6). The pups were weighed at birth and on postnatal days 7 and 14. At each of these time points, pups were killed and their lung growth was assessed on the basis of lung volume and light-microscopy morphometric data. At birth, body weight, total alveolar surface area, and alveolar surface density were significantly decreased and alveolar size was significantly increased in the L-NAME group, compared with the control group. On day 7, body weight was similar in the two groups, and the only significant difference was smaller total alveolar surface area in the L-NAME group. On day 14, neither body weight nor lung morphometric parameters were significantly different between the L-NAME group and the controls. These results suggest that postnatal catch-up growth may completely correct the lung development disorders present at birth in IUGR pups, in parallel with the catch-up body weight gain.

Animals↗
PubMed2005

Parasympathetic airway response and heart rate variability before and at the end of methacholine challenge.

BACKGROUND: The autonomic nervous system plays a primary role in regulating airway caliber, and its dysfunction is likely to contribute to the pathogenesis of airways diseases. Moreover, some findings support the hypothesis that autonomic dysfunction and/or dysregulation contributes to the pathogenesis of airway hyperresponsiveness (AHR). Heart rate variability (HRV) spectral analysis allows identifying noninvasively perturbations of the autonomic system. PURPOSES: We tested the relationship between AHR and cardiac parasympathetic tone assessed by HRV spectral analysis in patients submitted to a diagnostic methacholine bronchial challenge (MBC). METHODS: Fifteen women and 38 men (age range, 18 to 56 years) participated in the study. The principal indications for MBC were suspected asthma, chronic cough, unexplained exercise-induced dyspnea, or cough. The R-R intervals were continuously recorded during the MBC. Autoregressive method was performed on two series of 256 R-R intervals extracted before and after the MBC to obtain low-frequency (LF) and high-frequency (HF) components. RESULTS: The MBC distinguished 29 subjects without airway responsiveness (R-) and 24 responder or hyperresponsive subjects (R+): mean provocative dose of methacholine causing a 20% reduction in mean (+/- SD) FEV1 of 467 +/- 351 microg (range, 70 to 1,426 microg). The HF component expressed in normalized units (n.u.) [the index of parasympathetic modulation] was significantly higher in R+ than in R- at baseline, before MBC (21 +/- 21 n.u. vs 11 +/- 9 n.u., p < 0.05). Interestingly, R+ showed a significant increase of HF component after MBC (243 +/- 30 to 567 +/- 620 ms2 and 21 +/- 21 to 34 +/- 30 n.u., p < 0.01). For all subjects, HF (n.u.) calculated at baseline and after MBC were significantly influenced by the bronchial responsiveness (r2 = -0.28 and -0.51, respectively; p < 0.001). CONCLUSION: In summary, we found that R+ had a significantly higher parasympathetic tone than R- at baseline, and that R+ showed a significant increase in cardiac reactivity after bronchial challenge. These findings demonstrate that the autonomic nervous system, which contributes to the pathogenesis of AHR, is closely linked to cardiac modulation.

Adolescent↗
PubMed2004

Spectral analysis of heart rate variability during exercise in trained subjects.

PURPOSE: To investigate the effects of strenuous exercise on heart rate variability (HRV). METHODS: We evaluated the effects of exercise intensity and duration on HRV indices in 14 healthy trained subjects. Each subject exercised for 3, 6, and 9 min at 60 and 70% of the power achieved at maximal oxygen consumption (PVO2(max)) and for 3 and 6 min (or 3 min twice) at 80% of PVO2(max). The electrocardiogram RR intervals were recorded then processed by fast(FFT) and short-time (STFT) Fourier transform for determination of low-frequency (LF, 0.045-0.15 Hz) and high-frequency (HF, 0.15-1.0 Hz) components. RESULTS: The LF and HF components expressed as absolute power (ms2) decreased significantly at the onset of exercise (P < 0.05). However, with increasing exercise intensity, the HF component expressed as normalized units (n.u.) (reflecting parasympathetic modulation) increased significantly, whereas the LF component (n.u.) and LF/HF ratio (both reflecting sympathetic modulation) decreased significantly (P < 0.05). STFT showed that increasing exercise intensity was associated with a shift in HF peak frequency related to an increase in respiratory rate and a marked decrease in LF power (ms2). Moreover, HFn.u. rose (r = 0.918, P < 0.01) and LFms2 fell as minute ventilation increased (r = 0.906, P < 0.01). CONCLUSIONS: Parasympathetic respiratory control and nonautonomic mechanisms may influence the HF-peak shift during strenuous exercise. HRV and the usual indexes of sympathetic activity do not accurately reflect changes in autonomic modulation during exhaustive exercise.

Adult↗
PubMed2004

[Sports and cardiorespiratory function].

Regular physical training is generally considered to help prevent numerous diseases. These beneficial effects of aerobic exercise are particularly well established with regard to cardiovascular and respiratory functions. However, exhaustive exercise is clearly a risk in some athletes who have not undergone a correct and complete assessment of cardiovascular and respiratory functions. Exercise training is a crucial tool in integrative rehabilitation programs for patients with chronic heart failure and respiratory diseases.

Cardiovascular Physiological Phenomena↗
PubMed2003

Pulmonary function tests in preschool children with asthma.

Pulmonary function tests are seldom performed in preschool children with asthma. The aim of this multicenter study was to compare pulmonary function in 74 preschool children with asthma (height of 90-130 cm) and 84 healthy control subjects. Functional residual capacity (helium dilution technique) and expiratory interrupter resistance (interrupter technique) were measured. As compared with control children, children with asthma had a significantly higher resistance (0.77 +/- 0.20 vs. 0.92 +/- 0.22 kPa. L-1. second, p < 0.001) and significantly lower specific expiratory interrupter conductance (p < 0.005) values. Resistance values were significantly higher in children with asthma with than without symptoms on exertion (p < 0.05). The effect of bronchodilator administration, expressed as the percentage of baseline and predicted resistance values, was significantly greater in children with asthma than in control subjects (-18.6 +/- 13.6% vs. -11.2 +/- 15.2%, p </= 0.001, and -23.2 +/- 19.2% vs. -12.6 +/- 17.8%, p < 0.001), respectively. A 35% decrease in resistance after bronchodilation expressed as the percentage of predicted values had a likelihood ratio of 3 for separating the bronchodilator response in children with asthma from that in healthy control subjects. Pulmonary function tests that do not require active cooperation may help in the management and follow-up of preschool children with asthma who are unable to perform forced expiratory maneuvers.

Asthma↗
PubMed2003

Accounting for flow dependence of respiratory resistance during exercise.

Studies of airway function during exercise have produced conflicting results both in healthy and diseased subjects. Respiratory resistance (Rrs) was measured using an impulse oscillation technique. A flow/resistance curve was established for each of 16 healthy males during voluntary hyperventilation (VHV) at rest. Then, Rrs and flow were measured immediately (t(0)) and 90 sec (t(90)) after exercise on a cycle ergometer at 60, 70, and 80% of maximal aerobic power. The flow/resistance relationship at rest during VHV was used to assess the flow dependence of Rrs. Rrs at t(0) was higher than at rest (P <0.01) but lower than Rrs obtained at matched flow during VHV (P <0.05). In healthy subjects, the linear increase in Rrs with VHV indicates airflow dependency of Rrs following Rohrer's equation. The relative decrease in Rrs with exercise suggests bronchodilation. The bronchodilating effect disappeared promptly when exercise was stopped suggesting that it may have been related to a reflex mechanism.

Adult↗
PubMed2003

Strenuous exercise increases plasmatic and urinary leukotriene E4 in cyclists.

UNLABELLED: The purpose of this study was to investigate plasma and urinary levels of leukotriene (LT) and the changes in pulmonary function induced by strenuous exercise in highly trained cyclists (HT) with mild exercised-induced hypoxemia (EIH). METHOD: Nine HT and five untrained subjects (UT) performed a 30-min exercise at 78% of their VO2peak. Leukotriene E4 (LTE4) was assayed in plasma and urine. Pulmonary function tests and pulmonary diffusion capacity (DLCO) were examined before and after exercising. Ear arterialized blood gases were assessed at rest and during exercise. RESULTS: The mean drop in partial oxygen pressure was 15 mmHg in HT during exercise; and the DLCO decreased by 7.5% following exercise. No significant changes were found in forced vital capacity or forced expiratory flows. LTE4 levels increased significantly in HT following exercise: urinary LTE4 was 42.9 +/- 6.3 ng.mmol-1 creatinine at rest and 66.3 +/- 11.9 ng.mmol-1 creatinine 2 hrs after exercise, and plasma LTE4 rose from 528 +/- 91 pg.mL-1 at rest to 897 +/- 123 pg.mL-1 after exercise. By contrast, urinary LTE4 level was unchanged in the UT group. Among the HT group, there was no significant correlation between urinary LTE4 changes and PO2, air flow rates, or DLCO changes. CONCLUSION: These results suggest that strenuous exercise induces an increase of LTE4 release in highly trained cyclists with mild EIH. These changes in LTE4 levels were not related to significant impairment of lung function.

Adult↗
PubMed2002

Pulmonary function tests in preschool children with cystic fibrosis.

Pulmonary function tests have rarely been assessed in preschool children with cystic fibrosis (CF). The objective of this multicenter study was to compare pulmonary function in 39 preschool children with CF (height, 90-130 cm; 16 homozygous Delta F508) and in 79 healthy control children. Functional residual capacity (helium dilution technique) and expiratory interrupter resistance (Rint(exp)) (interrupter technique) were measured. As compared with control children, children with CF had significantly higher Rint(exp), expressed as absolute values and as Z-scores (1.05 +/- 0.36 versus 0.80 +/- 0.20 kPa.L(-1). second, p < 0.0001; and 1.31 +/- 1.72 versus 0.19 +/- 0.97, p < 0.0001), and significantly lower specific expiratory interrupter conductance (1.29 +/- 0.34 versus 1.63 +/- 0.43 kPa(-1). second, p < 0.0001). The effect of the bronchodilator salbutamol on Rint(exp) was not significantly different between children with CF and control children. Rint(exp) Z-scores were significantly higher in children with CF who were exposed to passive smoke (n = 8) (p < 0.03). Children with CF and with a history of respiratory symptoms (n = 31) had significantly higher functional residual capacity Z-scores (p < 0.02) and lower specific expiratory interrupter conductance Z-scores (p < 0.04). Genotype did not influence the data. We conclude that Rint(exp) and functional residual capacity measurements may help to follow young children with CF who are unable to perform reproducible forced expiratory maneuvers.

Airway Resistance↗
PubMed2002

Pre/postbronchodilator interrupter resistance values in healthy young children.

The interrupter technique estimates flow resistance. It entails occlusion of the airways during tidal breathing while flow and mouth pressure are recorded. This noninvasive technique is easy to use in young children. The aim of the present study was to measure inspiratory and expiratory interrupter resistance (Rint(insp), Rint(exp)) before and after bronchodilator administration in young healthy white children. We designed a multicenter study using a standardized procedure for Rint measurements. Centers in five French cities studied 91 children (48 boys and 43 girls; height, 92 to 129 cm; mean age 5.3 +/- 1.4 years). Mean values were not significantly different for Rint(insp) and Rint(exp) (0.78 +/- 0.21 versus 0.78 +/- 0.20 KPa x L(-1) x second). However, the difference between Rint(insp) and Rint(exp) decreased significantly with age and being positive before 5 years and negative later on (p < 0.02). Rint(insp) and Rint(exp) decreased significantly with height (Rint(insp) [KPa x L(-1) x second] = 2.289 - 1.37. 10(-2) x H [cm], Rint(exp) [KPa. L(-1) x second] = 2.021 - 1.12.10(-2) x H [cm]; p < 0.001). Bronchodilator (salbutamol) administration significantly decreased Rint(insp) and Rint(exp) (p < 0.001). Bronchodilator-induced changes (% of predicted values) in mean Rint(insp) and mean Rint(exp) were -15% (95% confidence interval, -46 to +15%) and -12% (95% confidence interval, -46 to +22%), respectively. Sex did not affect pre- or postbronchodilator values. Data from the present study may prove useful for testing lung function in young children with respiratory disorders who failed to cooperate with forced expiratory maneuvers.

Airway Resistance↗
PubMed2002

Nandrolone excretion is not increased by exhaustive exercise in trained athletes.

PURPOSE: The anabolic steroid nandrolone is widely used as a performance enhancer. Traces of its naturally occurring metabolite 19-norandrosterone (19-NA) have been found in human urine (below 0.6 ng.mL(-1)), and it has been suggested that strenuous exercise may increase urinary 19-NA. The aim of our study was to assess the effect of exhaustive exercise on the nandrolone excretion under controlled conditions in two groups of trained male athletes, one composed of judoka and the other of long-distance runners. METHODS: A Wingate test and a treadmill limited-time test (running at 85% (.)VO(2max)) were carried out on 14 judoka and 15 athletes. Hydration was controlled during each session. Urine samples were obtained before each test and 30 min, 60 min, and 24 h after each test. Urinary 19-NA concentrations were determined using gas chromatography coupled with mass spectrometry. RESULTS: Baseline urinary 19-NA concentrations varied widely across individuals, from undetectable levels to 0.250 ng.mL (-1)(mean, 0.048 +/- 0.050 ng.mL(-1)). The both exercise tests did not significantly modified urinary 19-NA levels in the two groups of subjects. CONCLUSION: Our study provides compelling evidence that endogenous nandrolone production in male athletes, during two very different types of exercise, produces urine levels far below the IOC threshold of 2 ng.mL(-1) urine. Thus, exercise does not induce endogenous nandrolone secretion.

Adult↗