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Biomedical subjects

B Housset

Publications and source records attributed to B Housset.

At least 19 recordsLinked to original sources
PubMed2001

Comparison of the forced oscillation technique and the interrupter technique for assessing airway obstruction and its reversibility in children.

The forced oscillation technique (FOT) and interrupter technique are particularly attractive for pediatric use as they require only passive cooperation from the patient. We compared the sensitivity and specificity of these methods for detecting airway obstruction and its reversibility in 118 children (3-16 yr) with asthma or chronic nocturnal cough. FOT (R(0) and R(16)) and interruption (Rint) parameters were measured at baseline and after bronchodilator inhalation (n = 94). Rint was significantly lower than R(0), especially in children with high baseline values. Baseline parameters were normalized for height and weight [R(SD)]. In children able to perform forced expiratory maneuvers (n = 93), the best discrimination between those with baseline FEV(1) < 80% or > or = 80% of predicted values was obtained with R(0)(SD). At a specificity of 80%, R(0)(SD) yielded 66% sensitivity, whereas Rint(SD) yielded only 33% sensitivity. Similarly, postbronchodilator changes in R(0)(SD) [DeltaR(0)(SD)] yielded the best discrimination between children with and without significant reversibility in FEV(1). At a specificity of 80%, DeltaR(0)(SD) yielded 67% sensitivity and DeltaRint(SD) yielded 58% sensitivity. In children unable to perform forced expiratory maneuvers (n = 25), FOT, contrary to the interrupter technique, clearly identified a subgroup of young children with high resistance values at baseline, which returned to normal after bronchodilation. We conclude that, in asthmatic children over 3 yr old, FOT measurements provide a more reliable evaluation of bronchial obstruction and its reversibility compared with the interrupter technique, especially in young children with high baseline values.

Adolescent↗
PubMed2001

Increased erythropoietin synthesis in patients with COLD or left heart failure is related to alterations in renal haemodynamics.

The mechanisms controlling erythropoietin (EPO) synthesis by the kidney in patients with chronic obstructive lung disease (COLD) or congestive left heart failure (CLHF) remain incompletely understood. Renal dysfunction occurs as a consequence of decreased renal blood flow (RBF) in these diseases. Because alterations in renal haemodynamics may affect EPO synthesis and red blood cell production, we investigated the potential relationships between renal function and plasma EPO synthesis in patients with COLD or CLHF. Thirty-two patients with COLD and 13 with CLHF underwent determination of renal physiology parameters, plasma EPO levels and haemoglobin levels. Plasma EPO concentrations were increased in patients with COLD or CLHF as compared to normal subjects, and were inversely correlated to haemoglobin concentrations. In patients with COLD or CLHF, plasma EPO was negatively correlated with both RBF and renal oxygen delivery (ROD) and positively correlated with filtration fraction. Plasma EPO was not correlated with glomerular filtration rate, fractional excretion of sodium, PO2 or PCO2. Among the patients with COLD, those with polycythemia (haemoglobin > 150 g L-1) had lower plasma EPO and higher RBF and ROD values than those with normocythemia (haemoglobin < or = 150 g L-1). Taken together, our data suggest that in patients with COLD or CLHF the critical determinant for EPO production is impairment of renal haemodynamics.

Adult↗
PubMed2001

Vascular endothelial growth factor synthesis in the acute phase of experimental and clinical lung injury.

Vascular endothelial growth factor (VEGF) is a potent angiogenic and endothelial survival factor, which is abundantly expressed in the normal lung. Conceivably, VEGF may be released by numerous cell types found around the airspaces, including alveolar type 2 cells, alveolar macrophages, and polymorphonuclear neutrophils. Using a bacteria-induced lung injury model in rats, VEGF expression in lung was investigated. Both VEGF protein and VEGF messenger ribonucleic acid (mRNA), 4 and 24 h after bacterial challenge (Pseudomonas aeruginosa), were decreased compared with sham rats. VEGF protein was also investigated in bronchoalveolar lavage (BAL) from patients studied within 7 days of acute respiratory distress syndrome (ARDS) onset and in patients without ARDS. VEGF protein levels in BAL were decreased in patients with ARDS versus those without (14.3 +/- 11.1 pg x mL(-1) versus 76.8 +/- 51.1 pg x mL(-1), p = 0.03). In aggregate, these findings show that the initial phase of acute lung injury is associated with a decrease in vascular endothelial growth factor in the lung. This downregulation may represent a protective mechanism aimed at limiting endothelial permeability, and may participate in the decrease in capillary number that is observed during early acute respiratory distress syndrome.

Animals↗
PubMed2001

Diagnosis of nosocomial pneumonia in medical ward: repeatability of the protected specimen brush.

The aims of this study were to assess the repeatability of two pairs of protected specimen brushes (PSB) done successively in the same lung area and either processed at the bedside or in the laboratory, and to provide a description of the bacteriological findings in 39 cases of suspected nosocomial pneumonia occurring in nonventilated patients. Four PSB were divided into two pairs. One pair of brushes (PB) was prepared at bedside and then sent to the laboratory; the other pair (PL) was immediately sent to the laboratory for complete processing. According to a 10(3) colony forming units (cfu) x mL(-1) threshold, 49% out of 156 PSB were positive. Using the 10(3) cfu x mL threshold, the PL brushes were 89.7% concordant while the PB brushes were 76.9% concordant. The repeatability as expressed by K-value of the cultures of PSB was higher for PL brushes than for PB brushes (K-values of 0.795 and 0.537 respectively, p=0.12). Bacterial species were isolated in 58.3% of 156 PSB (176 isolates). In 14 cases, cultures of PSB disclosed more than one micro-organism in a concentration > 10(3) cfu x mL(-1). The most frequently isolated organisms were Pseudomonas spp. (23.9%), Enterobacteriaceae (23.3%), Streptococcus spp. (21.6%) and Staphylococcus spp. (13.1%). Polymicrobial cultures were more frequent if the patient had a tracheostomy (seven out of the nine patients with a tracheostomy versus seven out of the 30 patients without a tracheostomy, p<0.01). Bacteriological discrepancies leading to a potential troublesome choice in antibiotherapy were observed in 31.8% of the patients for PL brushes and 56.5% of the patients for PB brushes. There is a low degree of repeatability of protected specimen brushes outside intensive care units which seem dependent on sampling processing. The distribution of pathogens found in case of suspicion of nosocomial pneumonia in nonventilated patients appears to be similar to that obtained in ventilator-associated pneumonia.

Adult↗
PubMed2001

Effects of levodopa on pulmonary function in Parkinson's disease.

STUDY OBJECTIVES: Upper-airway obstruction (UAO) may be present in patients with Parkinson's disease (PD), and its reversibility after levodopa therapy has been suggested. To investigate the effects of oral intake of levodopa on pulmonary function and UAO criteria in patients with PD, we studied 22 patients with PD. DESIGN: Pulmonary function tests were performed after a 12-h withdrawal of levodopa therapy, and 1 h after oral intake of placebo or levodopa, according to a double-blind, placebo-controlled, crossover study. Six UAO criteria were recorded to detect UAO in patients. UAO was found in 5 of 21 patients on baseline conditions (1 patient could not perform all tests). RESULTS: Among the patients with UAO, after levodopa therapy three of five patients did not meet the four of six required criteria for defining UAO. Levodopa produced its effects on UAO criteria by means of a saw-tooth pattern improvement and/or a decrease below the defined thresholds of the peak inspiratory flow and the FEV(1)/peak expiratory flow (PEF) and FEV(1)/forced expiratory flow after 50% of the FVC (FEV(0.5)) ratios. Levodopa PEF increased by 0.85 L/s in patients with UAO and by 0.24 L/s in patients without UAO, while after placebo it increased by 0.03 L/s in patients with UAO and decreased by 0.16 L/s in patients without UAO (p = 0.02). Whereas in patients without UAO an increase of the FEV(1)/PEF and FEV(1)/FEV(0.5) ratios was observed after placebo and levodopa intake, these ratios decreased after levodopa and increased after placebo in patients with UAO. CONCLUSIONS: These results show that levodopa administration in patients with PD induces significant variations in PEF and UAO ratios (FEV(1)/PEF and FEV(1)/FEV(0.5)).

Aged↗
PubMed2000

Use of tumor markers for differential diagnosis of mesothelioma and secondary pleural malignancies.

STUDY OBJECTIVE: The aim of the study was to assess diagnosis value of tumor markers for differential diagnosis between mesothelioma and other pleural tumors. DESIGN AND METHODS: Prospective study of 85 patients attending our hospital with malignant pleural effusion. The diagnostic approach involved routine pleurocentesis followed by pleural needle. When precise diagnosis was not achieved, thoracoscopy with pleural biopsies was performed. Carcinoembryonic antigen (CEA), hyaluronic acid, tissue polypeptide antigen and cyfra 21 to 1 were measured in serum and pleural fluid. RESULTS: By using receiver operating characteristics curves and area under curves, the best diagnostic characteristics were obtained with pleural and serum CEA concentrations. The area under the curve was larger for pleural ACE than for serum ACE. The sensitivity and specificity of a pleural CEA level exceeding 3 ng/mL for ruling out the diagnosis of mesothelioma were 100% and 77%, respectively. CONCLUSION: A CEA level above 3 ng/mL in pleural fluid eliminated the diagnosis of mesothelioma, whereas the other markers were not sufficiently discriminant. However, despite a negative predictive value of 100% at a cutoff of 3 ng/mL, CEA assay in pleural fluid only avoids a small number of diagnostic thoracoscopies.

Adenocarcinoma↗
PubMed2000

Role of adhesins and toxins in invasion of human tracheal epithelial cells by Bordetella pertussis.

Bordetella pertussis, the agent of whooping cough, can invade and survive in several types of eukaryotic cell, including CHO, HeLa 229, and HEp-2 cells and macrophages. In this study, we analyzed bacterial invasiveness in nonrespiratory human HeLa epithelial cells and human HTE and HAE0 tracheal epithelial cells. Invasion assays and transmission electron microscopy analysis showed that B. pertussis strains invaded and survived, without multiplying, in HTE or HAE0 cells. This phenomenon was bvg regulated, but invasive properties differed between B. pertussis strains and isolates and the B. pertussis reference strain. Studies with B. pertussis mutant strains demonstrated that filamentous hemagglutinin, the major adhesin, was involved in the invasion of human tracheal epithelial cells by bacteria but not in that of HeLa cells. Fimbriae and pertussis toxin were not found to be involved. However, we found that the production of adenylate cyclase-hemolysin prevents the invasion of HeLa and HTE cells by B. pertussis because an adenylate cyclase-hemolysin-deficient mutant was found to be more invasive than the parental strain. The effect of adenylate cyclase-hemolysin was mediated by an increase in the cyclic AMP concentration in the cells. Pertactin (PRN), an adhesin, significantly inhibited the invasion of HTE cells by bacteria, probably via its interaction with adenylate cyclase-hemolysin. Isolates producing different PRNs were taken up similarly, indicating that the differences in the sequences of the PRNs produced by these isolates do not affect invasion. We concluded that filamentous hemagglutinin production favored invasion of human tracheal cells but that adenylate cyclase-hemolysin and PRN production significantly inhibited this process.

Adenylate Cyclase Toxin↗
PubMed2000

Expression and regulation of vascular endothelial growth factor in human pulmonary epithelial cells.

Vascular endothelial growth factor (VEGF) is a potent endothelial cell growth and permeability factor highly expressed in rodent alveolar epithelium after injury and repair. To investigate VEGF synthesis in human lung epithelial cells, we examined VEGF expression by cultured cells under basal conditions and after cytokine treatment or oxidative stress. Basal VEGF expression was detected in transformed human epithelial cell lines (A549 and 1HAEo-) and in primary human bronchial epithelial cells with RT-PCR, Western blot, and immunocytochemistry. Among the cytokines tested, only transforming growth factor-beta1 increased the levels of excreted VEGF(165) as measured by ELISA. Under hypoxia (0% O(2) for 24 h), the VEGF(165) level increased fivefold, and this effect was O(2) concentration dependent. VEGF concentrations in the medium of all the cell types studied reached values similar to those found in bronchoalveolar lavage fluids from normal patients. Endothelial cells (human umbilical vein endothelial cells) exposed to conditioned medium from primary bronchial epithelial cell cultures showed an increased growth rate, which was inhibited in the presence of a specific neutralizing antibody to VEGF. These results suggest that lung epithelial cells participate in the endothelial repair and angiogenesis that follow lung injury through the synthesis of VEGF.

Bronchoalveolar Lavage Fluid↗
PubMed2000

Use of the forced oscillation technique to assess airway obstruction and reversibility in children.

The forced oscillation technique (FOT) is particularly attractive in a pediatric setting as it requires only passive cooperation from the child. We assessed the sensitivity and specificity of this method for detecting airway obstruction and its reversibility in 313 children (3 to 16 yr of age) with asthma or chronic nocturnal cough. Baseline and post-bronchodilator (n = 251) resistance were measured (R(0)) with the FOT. Baseline R(0) was normalized for height and weight [R(0)(SD)]. In children able to perform forced expiratory maneuvers (n = 181), R(0)(SD) was independently correlated with FEV(1) (p < 0.02) and maximal expiratory flow at 50% (MEF(50)) (p < 0.004). The optimal R(0)(SD) cutoff value given by receiver operating characteristic (ROC) curves to discriminate between children with baseline FEV(1) < 80% or >/= 80% of predicted values yielded 84% sensitivity and 73% specificity. Post-bronchodilator changes in R(0)(SD) [DeltaR(0)(SD)] were mostly correlated to changes in MEF(50). The optimal DeltaR(0)(SD) cutoff value to discriminate between children with the presence or absence of significant reversibility in FEV(1) yielded 69% sensitivity and 78% specificity. In children unable to perform forced expiratory maneuvers (n = 132), this DeltaR(0)(SD) cutoff clearly identified a subgroup of young children with high R(0) values at baseline, that returned to normal after bronchodilation. We conclude that FOT measurements allow reliable evaluation of bronchial obstruction and its reversibility in asthmatic children over 3 yr old.

Administration, Inhalation↗
PubMed2000

Continuous positive airway pressure during fiberoptic bronchoscopy in hypoxemic patients. A randomized double-blind study using a new device.

Fiberoptic bronchoscopy (FOB) may worsen oxygenation and clinical status in severely hypoxemic patients. We conducted a prospective, randomized double-blind trial to compare the delivery of continuous positive airway pressure (CPAP) as a tool for maintaining oxygenation during FOB, to the delivery of oxygen only. Thirty consecutive patients who needed FOB for diagnostic purposes were enrolled. Their arterial oxygen pressure (Pa(O(2))) to inspired oxygen fraction (FI(O(2))) ratio was below 300 mm Hg. CPAP was generated by a simple new device open to the atmosphere. During FOB and the 30 min thereafter, pulse oximetry values (Sp(O(2))) were significantly higher in the CPAP than the Oxygen group (95.7 +/- 1.9% versus 92.6 +/- 3.1, p = 0.02). The lowest Sp(O(2)) values were observed in the Oxygen group (93.5 +/- 2.4% versus 88.6 +/- 3.4, p = 0.002). Arterial blood gases 15 min after FOB showed that Pa(O(2)) had increased in the CPAP group and decreased in the Oxygen group (DeltaPa(O(2)) = +10.5% +/- 16.9 versus -15% +/- 16.6, p = 0.01). Five patients in the Oxygen group, but none in the CPAP group, developed respiratory failure in the 6 h after FOB and required ventilatory assistance (p = 0.03). We conclude that in hypoxemic patients, the use of a new CPAP device during FOB allowed minimal alterations in gas exchange and prevented subsequent respiratory failure.

Adult↗
PubMed2000

Predictive value of pulmonary function parameters for sleep apnea syndrome.

Nocturnal polysomnography is the standard diagnostic test for sleep apnea syndrome (SAS) but is both expensive and time-consuming. We developed a predictive index for SAS based on pulmonary function data, including respiratory resistance determined by the forced oscillation technique, from 168 obese snorers with suspected SAS. Our model used logistic regression to obtain case-by-case predictions of the probability of SAS, defined as an apnea-hypopnea index (AHI) > or = 15 during overnight polysomnography. We then tested our model in a prospective group of 101 similar patients. Specific respiratory conductance and daytime oxygen saturation contributed significantly to the model. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the index computed from these parameters were 98%, 86%, 90%, and 97%, respectively. In the prospective group, the model proved repeatable, with 100% sensitivity, 84% specificity, 86% PPV, and 100% NPV. The high NPV may help to identify obese snorers with a SAS risk that is so low as to make polysomnography unnecessary. Based on the 50% prevalence of SAS in our study and on the fact that polysomnography is required in all patients with daytime somnolence, we calculated that using our model would have obviated the need for polysomnography in 38% of our patients.

Female↗
PubMed2000

[Unusual cause of severe alveolar hypoventilation].

Mesenteric panniculitis is a rare disease of the adipose tissue of mesentery. Ascites is an unusual presentation. We report a case of panniculitis whose initial presentation was an obesity-hypoventilation syndrome with pulmonary hypertension. Respiratory disorders were related to abundant ascites. Panniculitis cure and ascites disappearance allowed return to normal pulmonary function and pulmonary artery pressure.

Aged↗
PubMed2000

[Evaluation of occupational exposures in lung cancer].

Occupational lung cancers are underestimated by the number of cases compensated in the French National Insurance System. Rules of compensation of occupational diseases were recently modified in France. Therefore a study was conducted on incident cases of lung cancer in a general hospital in the Paris area. The aim was to evaluate the exposure to carcinogens using data of a detailed specific occupational questionnaire, and to determine the number of cases who could receive compensation. Two hundred and seven subjects (171 males, 36 females, mean age = 64.5 years) were eligible in 1996, and 122 had an occupational questionnaire. Definite exposure to one or more occupational carcinogens in at least one job was identified in 50 subjects, the most frequent agent was asbestos (42 subjects). Claim for compensation was done in 32 subjects, mainly for asbestos (30 subjects). This study emphasizes the frequency of occupational exposure to carcinogens, and the usefulness of systematic occupational questionnaire in subjects having lung cancer. Social and financial consequences are important for these subjects. Further studies are needed, with recruitement of control subjects to allow calculation of the attributable risk to occupational factors in lung cancer.

Aged↗
PubMed1999

Evaluation of clinical case definitions of influenza: detailed investigation of patients during the 1995-1996 epidemic in France.

Using clinical predictors, we evaluated clinical case definitions of influenza during the 1995-1996 outbreak in France. Thirty-five general practitioners collected virological specimens and clinical data. Predictors of influenza virus infection were selected with logistic regression models. The results varied with the influenza virus subtype: temperature of >38.2 degrees C, stiffness or myalgia, rhinorrhea, and cough were predictive of influenza A/H3N2, whereas fatigue, lacrimation or conjunctival injection, and the absence of stiffness or myalgia were predictive of influenza A/H1N1. On the basis of this analysis and data from the literature, 12 clinical case definitions were evaluated for their abilities to diagnose influenza virus infection. They were associated with positive predictive values of 27% to 40% and negative predictive values of 80% to 91%. We conclude that focused studies evaluating clinical case definitions of influenza with use of subsets of patients should accompany population-based disease surveillance for optimal estimates of the disease burden associated with influenza epidemics.

Disease Outbreaks↗