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Biomedical subjects

R Matran

Publications and source records attributed to R Matran.

At least 19 recordsLinked to original sources
PubMed2004

Dynamic behavior of respiratory system during nasal continuous positive airway pressure in spontaneously breathing premature newborn infants.

The end-expiratory lung-volume level of premature newborn infants is maintained above passive resting volume during active breathing, through the combination of reduced time constant and high respiratory rate. To determine whether nasal continuous positive airway pressure (NCPAP) alters this characteristic dynamic breathing pattern, we studied the effects of various NCPAP levels on the dynamic elevation of end-expiratory lung volume level (DeltaEELV) in spontaneously breathing premature newborn infants, using respiratory inductive plethysmography (RIP). Eleven premature newborn infants with moderate respiratory failure were included. NCPAP levels were set in a random order to 0, 2, 4, and 6 cm H2O. Tidal volume (Vt), rib-cage contribution to Vt (%RC), phase angle between abdominal and thoracic motions (theta), respiratory rate (RR), and inspiratory and expiratory times (Ti and Te) were continuously recorded by RIP. The slope of the linear part of the expiratory flow-volume relation was extrapolated up to zero flow level to evaluate the dynamic elevation of the functional residual capacity (FRC) (DeltaEELV). The time-constant of the respiratory system (tauRS) was calculated as the slope of the linear part of the expiratory flow-volume loop. At NCPAP = 6 cm H2O, DeltaEELV reached 0.6 +/- 0.2 times the Vt at NCPAP = 0 cm H2O. An increase in NCPAP level resulted in a significant decrease in DeltaEELV (P < 0.01). A decrease in DeltaEELV during NCPAP was associated with a significant increase in Te from 0.62 +/- 0.13 sec at NCPAP = 0 cm H2O to 0.80 +/- 0.07 sec at NCPAP = 6 cm H2O (P < 0.05), and a decrease in tauRS from 0.4 +/- 0.1 sec at NCPAP = 0 cm H2O to 0.24 +/- 0.04 sec at NCPAP = 6 cm H2O (P < 0.01). These results indicate that the characteristic spontaneous breathing pattern causing a dynamic elevation of FRC is abolished by NCPAP. We speculate that the dynamic volume-preserving mechanisms resulting from expiratory flow braking are no longer required during NCPAP, as the constant pressure may passively elevate FRC.

Female↗
PubMed2003

Maximal lactate steady state does not correspond to a complete physiological steady state.

The purpose of this study was to verify whether the maximal lactate steady state (MLSS) corresponds to a physiological steady state. Eight male trained subjects performed a 30-min test on a cycle ergometer at a constant power corresponding to their own MLSS which had been previously determined. No significant variation was observed between the 10th and the 30th min for arterial lactate concentration, redox state, arterial oxygen pressure, arterial oxygen saturation, bicarbonates concentration, base excess, hematocrit, hemoglobin concentration, plasma volume, oxygen uptake, carbon dioxide output, gas exchange ratio, minute ventilation, ventilatory equivalents for oxygen and carbon dioxide, and arterial systolic blood pressure values. However, arterial carbon dioxide pressure and pH values were significantly different between the 10th and the 30th min (p < 0.01). Respiratory rate values and heart rate significantly increased (p < 0.01). These results indicate that MLSS does not correspond to a complete physiological steady state.

Adaptation, Physiological↗
PubMed2003

Plasma lactate and plasma volume recovery in adults and children following high-intensity exercises.

AIM: To compare plasma lactate concentration recovery kinetics when measured and corrected for variations in plasma volume between children and adults. METHODS: Nine boys (11.3 +/- 1.1 y) and 8 men (21.9 +/- 1.9 y) performed a maximal and a supramaximal exercise until exhaustion. Plasma lactate concentrations, haemoglobin and haematocrit were measured at rest, immediately on completion of exercise and after the 2nd, 5th, 12th and 30th minute of recovery. The plasma lactate concentrations and the rate of recovery were corrected for variations in plasma volume. RESULTS: The maximal decreases in plasma volume were significantly higher in adults than in children for maximal exercise (-18.7 +/- 2.6% vs -14.5 +/- 3.2%; p < 0.05), but similar for the supramaximal exercise (-16.9 +/- 3.4% vs -15.2 +/- 3.4%). During recovery, measured and corrected plasma lactate concentrations were significantly higher in adults. The rate of plasma lactate recovery was higher in adults for maximal exercise only. The same results were obtained when the rates of plasma lactate decrease were calculated from corrected plasma lactate concentrations. CONCLUSION: The correction of the plasma lactate concentrations for variations in plasma volume did not influence the comparison of the concentrations obtained in adults and children, or their rate of recovery.

Adult↗
PubMed2003

[Reproducibility of the shuttle walk test in children with cystic fibrosis].

INTRODUCTION: Exercise testing is useful in the respiratory evaluation of patients with cystic fibrosis. The shuttle walk test (SWT) is a progressive, externally paced, exercise test requiring the subject to walk/run back and forth between two fixed points. The aim is to assess the reproductibility of the SWT in paediatric patients with cystic fibrosis. METHODS: This prospective study recruited 31 children with stable disease. The patients performed two SWT one day (SWT 1 and 2) and two others (SWT 3 and 4) within 15 days. Only SWT 2 and 4 were assessed for reproducibility. RESULTS: 61% were boys, median age (range): 12.9 (7-18.9) years, median Shwachman score (range): 80 (65-100), median values for FEV1 and FVC (range): 92 (55-154) and 92 (64-140)% predicted, respectively. Median distance for SWT 2-4 (range): 910 (580-1020) and 925 (540-1020) metres. Reproducibility for SWT distance and physical activity measured by an accelerometer is very good (intra-class correlation coefficient=0.90 and 0.92, respectively). SWT distance correlated with physical activity (p=3.10(-4)) and weight (p=0.03). SWT distance was independent of the following parameters: height, weight-for-age Z-score, FEV1, FVC, Shwachman score, colonisation with Pseudomonas aeruginosa. CONCLUSIONS: The SWT is reproducible in paediatric patients with cystic fibrosis and provides assessment of respiratory performance that complements spirometric measures of lung function.

Adolescent↗
PubMed2001

Effects of nasal continuous positive airway pressure (NCPAP) on breathing pattern in spontaneously breathing premature newborn infants.

OBJECTIVE: The aim of the study was to assess the influence of nasal continuous positive airway pressure (NCPAP) on breathing pattern in preterm newborns. DESIGN: Prospective study. SETTING: Neonatal intensive care unit. PATIENTS: Ten premature newborn infants on NCPAP (gestational age range from 27 to 32 weeks, mean birth weight 1300+/-460 g) admitted in our neonatal intensive care unit (NICU) for respiratory distress syndrome. METHODS: Breathing patterns and changes in lung volumes level were obtained using respiratory inductive plethysmography (RIP), at random CPAP levels (0, 2, 4, 6 and 8 cmH2O). Raw data were analysed for end-expiratory lung volume level (EELV-level), tidal volume (Vt), respiratory rate, phase angle and labour breathing index (LBI). RESULTS: CPAP increased EELV-level by 2.1+/-0.3xVt from 0 to 8 cmH2O ( p<0.01). Vt increased by 43% from CPAP of 0 cmH2O to CPAP of 8 cmH2O ( p<0.01). We also found that CPAP lowered the phase angle (from 76+/-21 degrees at CPAP of 0 cmH2O to 30+/-15 degrees at CPAP of 8 cmH2O; p<0.01 ) and LBI (from 1.7+/-0.8 at CPAP of 0 cmH2O to 1.2+/-0.3 at CPAP of 8 cmH2O; p<0.05). CONCLUSION: NCPAP improves the breathing strategy of premature infants with respiratory failure, as reflected by improved thoraco-abdominal synchrony, increased Vt and reduction of the LBI. This effect is associated with an increase in EELV-level with CPAP level. However, further investigations are necessary to establish the best CPAP level that ensures both safety and efficiency.

Analysis of Variance↗
PubMed2001

Electrophysiological effects of corticosteroids on the retinal pigment epithelium.

PURPOSE: As corticosteroids appear to intervene in pathogenesis of central serous chorioretinopathy, ion transport changes within the retinal pigment epithelium (RPE) might be involved. Electrophysiological responses to corticosteroid administration were recorded in vivo and in vitro. METHODS: Clinical study: The standing ocular potential was recorded during intravenous (IV) infusion of glucose 5% and glucose 5% + prednisolone 0.2% in 14 patients with relapsing multiple sclerosis. The results were compared with a control group receiving two successive identical glucose 5% infusions. In vitro study: Native tissue explants (RPE + choroid, porcine, and bovine) were placed in a Ussing-type chamber. After baseline determination of the transepithelial potential (PD), short circuit current (I(sc)) and transepithelial resistance (R(t)), the effect of apical hydrocortisone (HC) 10(-4) M was determined. RESULTS: Clinical study: A significant rise of the standing potential was found after glucose infusion (P = 0.005), whereas no change was detected after IV glucose + prednisolone (P = 0.695). In vitro study: In the porcine RPE, the mean baseline PD and I(sc) were significantly reduced (both P: = 0.012) after applying apical 10(-4) HC. R(t) was also significantly reduced (P = 0.01). The same type of response, observed in bovine RPE, was reduced in low chloride/low bicarbonate conditions. CONCLUSIONS: Corticosteroids modified electrophysiological parameters representing RPE function in vivo. The existence of an RPE-specific effect was confirmed in vitro. Further work is required to link the observed ion transport changes to a reduction of apical, subretinal fluid absorption.

Animals↗
PubMed2001

[Epidemiological study of genetic and environmental factors in asthma, bronchial hyperresponsiveness and atopy. Protocol and potential selection bias].

BACKGROUND: The EGEA study combines a case-control study and a family study to assess genetic and environmental risk factors and their interactions for asthma, bronchial hyperresponsiveness and atopy. Information is scanty regarding potential selection biases, in particular regarding familial ressemblance in epidemiological surveys of this kind. METHODS: Asthmatic probands (adult and paediatric) were recruited in chest clinics of six clinical centres. Controls were mostly population-based (electoral rolls) for adults and recruited in surgery departments for children. RESULTS: The population examined includes 348 nuclear families ascertained by one asthmatic and 416 controls, totalling 1847 subjects (EGEA I) and an additional sample of 40 families ascertained by two asthmatic siblings (EGEA II). Potential biases for the various types of analyses have been studied. Quantification of the consequences of the greater participation of probands with a parental history of asthma shows it does not introduce a major bias in the estimates of familial resemblance. Cases and controls showed a good comparability regarding sex, age, area of residence and familial geographical origin, allowing proper associations studies for environmental and candidate genetic factors. CONCLUSIONS: The case-control component of the study will allow to perform studies on environmental factors and association studies for various genetic polymorphisms. Using the family base collected, segregation and genetic linkage/association analyses with DNA markers may be performed.

Adult↗
PubMed2000

Genome screen for asthma and related phenotypes in the French EGEA study.

A genome-wide search was conducted in 107 nuclear families with at least two siblings with asthma, as part of the French EGEA study. A two-stage analysis strategy was applied to the 107 families divided into two independent subsets of 46 and 61 families, where all regions detected in the first set of families were tested for replication in the second set. In addition, all regions reported by published genome scans in different populations were examined in the total sample. A total of 254 markers were typed in the first set of families and 70% of them in the second set. Linkage was investigated by model-free methods for asthma and four asthma-related phenotypes: bronchial responsiveness (BR), skin test response, total immunoglobulin E (IgE) levels, and eosinophil count. The two-stage analysis led to the detection of three regions: 11p13 for IgE, 12q24 for eosinophils, and 17q12-21 for asthma and skin tests. Among the regions reported by published genome screens, seven were found in the 107 French EGEA families: three being already detected by the two-stage analysis, 11p13 (p = 0.005), 12q24 (p = 0.0008), and 17q12-21 (p = 0.001), and four additional ones, 1p31 (p = 0.005) for asthma, 11q13 (p = 0.006) for IgE, 13q31 (p = 0.001) for eosinophils, and 19q13 (p = 0.02) for BR.

Adolescent↗
PubMed1999

The effect of zafirlukast on repetitive exercise-induced bronchoconstriction: the possible role of leukotrienes in exercise-induced refractoriness.

BACKGROUND: Single doses of zafirlukast attenuate exercise-induced bronchoconstriction (EIB), but previous studies have not measured zafirlukast's effects after regular dosing or its duration of effect beyond 4 hours. OBJECTIVE: The purpose of this study was to assess the effects of zafirlukast 20 mg and 80 mg twice daily compared with placebo on exercise challenges performed at 2 and 8 hours after the last dose of regular administration. METHODS: Twenty-four adult patients with stable asthma taking beta(2)-agonists, inhaled corticosteroids, or both received treatment with zafirlukast (20 mg and 80 mg) and placebo. The patients were treated twice daily for 14 days in a randomized, double-blind, 3-way cross-over fashion, with a 7-day washout period between each treatment. Exercise challenges were performed at 2 and 8 hours after the morning dose on day 14. FEV(1) was measured before exercise and at set intervals after exercise until it returned to within 7% of its baseline value. RESULTS: Both zafirlukast treatments significantly reduced EIB, as measured by the area under the FEV(1) time curve after the 2-hour (P <.001) and 8-hour (P <.001) exercise challenges and maximum fall in FEV(1) at the 2-hour challenge (P <.001). The comparison at 8 hours between treatments was affected by the unexpected finding that EIB was less in the placebo group after the 8-hour challenge than after the 2-hour challenge, as measured by the within-group change in the maximum fall in FEV(1) (P <.001) and the area under the FEV(1) time curve (P =.0023). CONCLUSION: Regular zafirlukast treatment protects against EIB for at least 8 hours after regular dosing. A refractory period, which may be caused by exercise-induced leukotriene release, may last for up to 6 hours after the initial response to exercise.

Adolescent↗
PubMed1999

EGEA (Epidemiological study on the Genetics and Environment of Asthma, bronchial hyperresponsiveness and atopy)-- descriptive characteristics.

The Epidemiological study on the Genetics and Environment of Asthma (EGEA) was planned to assess genetic, environmental risk factors and their interactions for asthma and for the two related traits of bronchial hyperresponsiveness and atopy. The population examined includes 348 nuclear families ascertained by one asthmatic (213 adult and 135 paediatric probands) and 416 controls, totalling 1,847 subjects (EGEA I). Prevalences of asthma, skin prick test response, high IgE and bronchial hyperresponsiveness were for parents, siblings, and offspring of cases intermediate between cases and spouses or controls, both in adults and children, confirming the familial resemblance for asthma and related traits. With an additional sample of 40 families ascertained by two asthmatic siblings (EGEA II), a total of 119 families with two asthmatic siblings has been ascertained for a genome screening.

Adolescent↗
PubMed1998

Relationships between nasal potential difference and respiratory function in adults with cystic fibrosis.

This study investigated the relations between nasal transepithelial electric potential difference (PD) and the phenotype and genotype of cystic fibrosis (CF) adult patients. Basal nasal PD was measured in 95 adult CF patients who were classified into three groups of nasal PD (expressed as absolute values) according to the 10th and the 90th percentiles (28.3 and 49.2 mV, respectively), which defined group 1 (nasal PD < or =28.3 mV), group 2 (nasal PD 28.3-49.2 mV) and group 3 (nasal PD > or =49.2 mV). Patients from group 1 had a higher forced vital capacity (FVC) than patients from groups 2 and 3 (76.5+/-22.4 versus 57.4+/-21.2 and 55.7+/-21.1% predicted, respectively, p<0.05) and a higher forced expiratory volume in one second (FEV1) (69.3+/-24.0 versus 42.5+/-22.4 and 42.2+/-21.4% pred, respectively, p<0.01). Among patients with severe mutations (deltaF508 homozygotes, or one deltaF508 mutation plus another "severe" mutation, or two "severe" mutations), patients from group 1 had a higher FVC, FEV1 and arterial oxygen tension than patients from groups 2 and 3 (p<0.05 for each comparison). The results show that in adult cystic fibrosis patients a normal basal nasal potential difference is related to milder respiratory disease, irrespective of the severity of the genotype.

Adolescent↗
PubMed1996

Genotype-phenotype relationships in a cohort of adult cystic fibrosis patients.

In cystic fibrosis (CF), relationships between genotype and phenotype have been shown for pancreatic status but not for pulmonary disease. One hundred and ten adult CF patients were classified according to the expected effect of their mutations on cystic fibrosis transmembrane conductance regulator (CFTR) protein: Group 1 (n=48) included deltaF508 homozygotes; Group 2 (n=26), patients with two "severe" mutations and no expected CFTR production; Group 3 (n=17), patients with expected partly functional CFTR corresponding to at least one "mild" mutation; Group 4 (n=19), patients with no mutation identified or only one identified "severe" mutation. As compared to Groups 1 and 2: patients from Groups 3 and 4 had higher arterial oxygen tension (Pa,O2) (9.5+/-1.9 and 9.9+/-1.5 vs 8.8+/-1.5 and 8.3+/-1.7 kPa, respectively p<0.02); and a slower decline in their pulmonary function, estimated by the mean annual loss in forced vital capacity (FVC) (1.2+/-1.0 and 1.5+/-1.1 vs 2.0+/-0.9 and 2.2+/-1.0%, respectively; p<0.01) and in forced expiratory volume in one second (FEV1) (1.7+/-1.1 and 1.9+/-1.3 vs 2.6+/-1.0 and 2.8+/-1.0%, respectively; p<0.005). They had fewer episodes of colonization of the airways by Pseudomonas aeruginosa, and colonization occurred at a more advanced age (median age 25 and 19 vs 15 and 17 yrs, respectively; p<0.01) and required fewer intravenous antibiotic courses (p<0.01). Pancreatic insufficiency was less frequent in Groups 3 (23%) and 4 (63%) than in Groups 1 (100%) and 2 (96%). This study suggests that the phenotype of adult cystic fibrosis patients, including the severity of the lung disease, is related to the severity of the cystic fibrosis transmembrane conductance regulator mutations.

Adolescent↗
PubMed1996

[Measurement of nasal transepithelial potential difference: a diagnostic test for cystic fibrosis].

Measurement of nasal transepithelial potential difference allows the exploration of transepithelial ionic transports in vivo. Cystic fibrosis is an interesting indication of this test. Indeed, this disease is characterized by a chloride and water secretion deficit across respiratory epithelium. We have measured nasal potential in 8 healthy volunteers. Measurements were repeated 3 times a day, during 3 days for each subject. The reproducibility of the data was analysed with factorial variance model. The mean nasal potential in the healthy volunteers group and in 10 patients with cystic fibrosis was compared. In the cystic fibrosis group, the nasal potential was measured 3 times with a 2 mn-interval between the measurements. No significant variation of the nasal potential values was found from day to day or in the same day from one measurement to another. Mean value was -19 +/- 3.5 mv in normal subjects and -42.6 +/- 5.1 mv in cystic fibrosis patients. We conclude that nasal potential measurement is an easy and reproducible test that might be a complementary tool routinely used along with the classical tests in the diagnosis of cystic fibrosis.

Adult↗
PubMed1996

Evidence of a strong, positive association between atopy and the HLA class II alleles DR4 and DR7.

BACKGROUND: Atopy, with or without associated asthma, provides a useful model for evaluating the genetic factors that control human immune responsiveness. HLA class II gene products are involved in the control of immune responses. OBJECTIVES: We investigated whether susceptibility or resistance to the disease was associated with HLA class II genes. METHODS: Blood samples were obtained from two groups of unrelated European-born white adults: 56 atopic patients (52 of them with asthma) and 39 healthy controls with no personal or familial history of asthma or atopy. Genomic DNA was extracted from peripheral blood lymphocytes. The exons of DQA1, DQB1, DRB and DPB1 genes were selectively amplified by the polymerase chain reaction (PCR) method. Genotyping was carried out by digestion of the amplified DNA products with allele-specific endonucleases (PCR-RFLP), which can recognize allelic variations in the polymorphic exon. RESULTS: We found no significant differences in the frequency of DPB1 alleles between patients and controls. HLA class II DR4 and DR7 alleles were present in 39.2% of the patients and in 2.5% of the healthy subjects (Pc*2 < or = 3.9 10(-3)). Conversely, DQA1*0103 and DQB1*0502 alleles were more frequent in the control subjects. These results confirm a previous study of an extended pedigree, which showed that DR4 and DR7 alleles were absent in all healthy members of the family and were frequently observed in atopic and/or in asthmatic subjects. CONCLUSION: We observed that HLA-DR 4 and DR7 alleles are significantly implicated in their susceptibility to the disease and suggest that this susceptibility is more related to atopy than to specific responses to allergens. According to previous studies, we could also submit that in atopic patients with asthma, DR4 alleles at the least, could be more closely associated with atopy than with asthma per se. Conversely, we suggest that some allelic DQA1 and DQB1 sequences might confer protection against the disease.

Adult↗
PubMed1995

Sympathetic vascular control of the laryngeo-tracheal, bronchial and pulmonary circulation in the pig: evidence for non-adrenergic mechanisms involving neuropeptide Y.

Neuropeptide Y (NPY) and noradrenaline (NA) are co-stored in sympathetic perivascular nerves of the airway mucosa and lung. THe superior laryngeal, bronchial and pulmonary vascular responses were therefore studied in anaesthetized pigs after systemic injections of NPY and NA and after stimulation (2 or 10 Hz, 15 V, 5 ms) of the cranial and caudal portions of hte cervical sympathetic trunk or the stellate ganglia. NPY and NA increased vascular resistance, suggesting vasoconstriction in all three vascular beds. Stimulation of the cervical sympathetic trunk in the cranial direction caused clear-cut vasoconstriction and a decrease in the superficial blood flow in the laryngeal and tracheal circulation supplied by the superior laryngeal artery. This vascular response may be related to release of NA at 2 Hz and possibly also NPY at 10 Hz, since a remaining vasoconstrictor response at 10 Hz was present in reserpinized preganglionically transected pigs when tissue content of NA but not NPY was depleted. The decrease in superficial blood flow in the tracheal mucosa on sympathetic stimulation was absent after reserpine, however. Stimulation of the cervical sympathetic trunk in caudal direction provoked vasoconstriction in the bronchial and pulmonary vascular beds in control pigs. The basal tone of these two vascular beds was not influenced on electrical stimulation after reserpine pretreatment, however, suggesting involvement of NA and possibly aslo NPY, which were both depleted by reserpine. Electrical stimulation of the stellate ganglia also evoked reserpine-sensitive vasoconstriction in both the bronchial and pulmonary vascular beds. The left stellate ganglion dominated the vasomotor response in the bronchial circulation, whereas the right side mainly influenced the pulmonary circulation and the heart.

Animals↗