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Biomedical subjects

G J Huchon

Publications and source records attributed to G J Huchon.

At least 19 recordsLinked to original sources
PubMed1998

Metered-dose inhaler to deliver methacholine in bronchial provocation testing: a pilot study.

BACKGROUND: Nonspecific bronchial provocation tests may be simplified by the use of hand-held devices to deliver methacholine. OBJECTIVE: To study the feasibility of using a metered-dose inhaler (MDI) to administer methacholine in bronchial provocation tests, and the ability of such a device to diagnose bronchial hyperresponsiveness (BHR) accurately. METHODS: In an open randomized crossover pilot study, we compared the provocative dose that induces a 20% fall in FEV1 (PD20 FEV1) obtained with the methacholine MDI with that obtained using a conventional nebulizer in 20 hyperresponsive and 20 nonhyperresponsive subjects. The MDI delivers 400 doses of 100 microg of methacholine, and was used via a spacer. Bronchial hyperresponsiveness (BHR) was defined as a PD20 FEV1 <2,000 microg with the conventional test using the nebulizer. The tests were performed in each subject in a randomized order, 1 to 7 days apart. RESULTS: Of the subjects who had a nebulizer PD20 FEV1 <2,000 microg, all but one had an MDI PD20 FEV1 <800 microg. When 800 microg was taken as the threshold for the diagnosis of BHR with the MDI test, the accuracy of this test to diagnose BHR was 97.5%, and the two tests were highly concordant for the diagnosis of BHR (Pearson chi2, 36.19; p<0.0001). CONCLUSION: A hand-held device may be suitable for delivery of methacholine during bronchial provocation tests, if these results are confirmed in large samples.

Adult↗
PubMed1997

Current issues in the management of chronic obstructive pulmonary diseases.

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality, especially among smokers. Many guidelines that have recently been issued emphasize that COPD is not inaccessible to therapeutic measures: although few interventions are capable of affecting its natural history (i.e. smoking cessation and, in patients with severe resting hypoxaemia, oxygen therapy), several others have a demonstrated effect on symptoms and, thereby, quality of life. The effects of inhaled corticosteroids, and alpha 1-antitrypsin replacement therapy in emphysema due to alpha 1-antitrypsin deficiency are currently being studied. When there is a marked increase in mucus production, chest physiotherapy using controlled expiration and directed cough may be useful. Inhaled bronchodilators are frequently effective on dyspnoea, anticholinergic agents being more suitable for continuous symptoms. Rehabilitation, which includes education and psychosocial care, chest physiotherapy, nutritional care and exercise training, also improves quality of life. When there is persistent severe alveolar hypoventilation despite oxygen therapy, long-term mechanical ventilation may be considered. Surgical options in the treatment of emphysema include resection of giant bullae and lung volume reduction surgery. Lung transplantation should be proposed only in patients with end-stage disease, the difficulty here being to define what 'end-stage' means. Finally, all preventive and some therapeutic interventions are likely to be more effective early in the course of the disease. Thus, efforts should be made to detect airways obstruction early in subjects at risk, such as smokers.

Combined Modality Therapy↗
PubMed1997

Allergic and nonallergic interactions between house dust mite allergens and airway mucosa.

Asthma and allergy are extremely frequent diseases, affecting 5-10% and 30% of the population, respectively. The prevalence of asthma has increased in many developed countries, which may be due to several factors, including increased exposure to house dust mite (HDM) allergens. HDM to which humans are most frequently sensitized are Dermatophagoides pteronyssinus, Dermatophagoides farinae, and Euroglyphus maynei. These mites multiply in carpets, bedding and upholstered furniture in a hot and humid atmosphere. The allergens are digestive enzymes of the mites. Several epidemiological studies have shown that an increase in exposure to HDMs is associated with an increase in the prevalence of sensitization and asthma, whereas mite avoidance leads to a decrease in respiratory symptoms of sensitized asthmatic subjects. Sensitized subjects have specific immunoglobulin G and E (IgG and IgE) humoral responses, as well as proliferative T-cell responses to HDM allergens. Experimental exposure to HDM allergens induces bronchoalveolar inflammatory responses, that are characterized by the recruitment and activation of eosinophils, mastocytes, neutrophils, monocytes and lymphocytes. The cysteine protease activity of Der p 1 (a major allergen of D. pteronyssinus) has been shown to increase airway mucosal permeability, and may thereby contribute to the pathogenesis of airway inflammation and hyperresponsiveness by nonimmunological mechanisms. These epidemiological and experimental data support the recommendations for mite avoidance, especially in persons at high risk of developing asthma.

Allergens↗
PubMed1996

Initial antibiotic therapy for lower respiratory tract infection in the community: a European survey.

A survey of first-line antibiotic prescription in community-acquired lower respiratory tract infection (LRTI) by general practitioners (GP) was carried out simultaneously, using the same methodology in France, Germany, Italy, Spain and the UK. Data were obtained from 2,056 patients and 605 GPs. There was no antibiotic prescription in 17% of all LRTIs and 13% of community-acquired pneumonia (CAP) in the five countries taken together; and in 32% of all LRTIs and in 23% of CAP in Germany. Of patients with acute bronchitis, exacerbation of chronic bronchitis and viral lower respiratory tract infection, 87, 92 and 71% received antibiotics, respectively. The most frequent prescriptions were penicillins in France and the UK, third-generation cephalosporin in Italy, tetracycline in Germany and macrolide in Spain. The daily dosage of aminopenicillin prescribed was: 41% <1.5 g; 49% > or = 1.5 g and <3 g; and 10% > or = 3 g. In Italy, 53% of all antibiotics were injected in all LRTIs, and 71% in CAP; in contrast, antibiotic injection was lower than 2% both in the UK and Germany, with an average of 14% in the five countries combined. We conclude that there are variations in antibiotic prescription by GPs in Western Europe; differences are likely to be multifactorial, but could, in part, be explained by differences in health systems and sources of information available to GPs.

Adult↗
PubMed1996

Use of investigations in lower respiratory tract infection in the community: a European survey.

A questionnaire survey was performed on the use of investigations and their impact on treatment of adult lower respiratory tract infection in the community. Data on the management of 2,056 such infections were obtained simultaneously from general practitioners in France, Germany, Italy, Spain and the UK. Diagnostic tests were only performed in 29% of cases. Chest radiographs were performed most frequently (22%), followed by peripheral blood white cell count (15%) and microbiological examination of sputum (7%), with major differences being found in the frequency of these tests both by clinical diagnosis and country. A change in initial antibiotic therapy was made in 12% of cases, with use of investigation being significantly linked to such changes. Second- and third-line antibiotics were significantly different to first-line therapy, with macrolides the most frequently prescribed second-line and quinolones the most frequently prescribed third-line antibiotics.

Adult↗
PubMed1996

Respiratory symptoms and peak expiratory flow in survivors of the Nyos disaster.

In August 1986, gases from the Nyos volcanic lake killed 1,746 persons in northwestern Cameroun, but 1,500 others living in the affected area survived. Gas emanations contained carbon dioxide, sulfur dioxide, and hydrogen sulfide. The objective of this study was to evaluate the delayed respiratory consequences of the inhalation of such volcanic gases. Two groups of subjects living in the same area, exposed (Nyos group; n = 381) or not exposed (control group; n = 128) to Nyos gases, were evaluated with a short questionnaire and by measurement of peak expiratory flow (PEF, percent predicted) in March 1991. Eleven percent of the subjects smoked, more often men than women (23% vs 4%; p < 0.001). In the whole population (exposed and unexposed), smoking was associated with a 3.6-fold increase in the frequency of cough (p < 0.001) and with a 6-fold increase in the frequency of sputum production (p < 0.005), but not with a decrease in PEF. There was no difference in the frequency of dyspnea, cough, sputum production, and PEF between Nyos and control groups. We conclude that 55 months after the emanation of gases from Nyos volcanic lake, there was no difference in respiratory symptoms, and PEF between survivors who inhaled volcanic gases and control subjects, whereas smoking was associated with cough and sputum production.

Adolescent↗
PubMed1994

Mechanisms of increased epithelial lung clearance of DTPA in diffuse fibrosing alveolitis.

The aim of this study was to elucidate possible mechanisms of increased epithelial lung clearance in diffuse fibrosing alveolitis (DFA). We investigated the relationships between epithelial lung clearance as assessed by the clearance of aerosolized 99mTc-diethylene-triamine-penta-acetic acid (RC-DTPA), luminal alveolitis as assessed by bronchoalveolar lavage, and pulmonary function, in 30 nonsmokers with DFA. In 14 of these patients, RC-DTPA and lung function were determined before and during therapy with prednisolone (0.5 mg.kg-1 daily). RC-DTPA was higher in patients with DFA (4.45 +/- 2.50%.min-1) than in normal subjects (1.18 +/- 0.31%.min-1). RC-DTPA did not correlate with the number of alveolar neutrophils, but correlated positively with the number of alveolar lymphocytes, and negatively with vital capacity (VC). RC-DTPA decreased from 6.1 +/- 2.8 to 3.8 +/- 1.9%.min-1 with prednisolone. RC-DTPA before prednisolone correlated positively with the prednisolone-associated improvement in VC. We conclude that in patient with DFA, RC-DTPA is increased, and decreases but does not return to normal with corticosteroid therapy. Our data suggest that in DFA the increase in RC-DTPA could be related to the recoil-induced stretch of the respiratory epithelium and to alveolar lymphocytic inflammation.

Aerosols↗
PubMed1992

Bronchial clearance of DTPA is increased in acute asthma but not in chronic asthma.

To investigate bronchial permeability in asthma, we measured the bronchial clearance of 113mIn-DTPA in seven asthmatics during and after an acute attack of asthma, seven asthmatics with chronic airflow limitation, and seven asthmatics without airflow limitation but with bronchial hyperresponsiveness to methacholine. We compared these results with those from seven normal subjects, seven patients with chronic bronchitis and bronchial infection, and seven patients with emphysema. An aerosol of 113mIn-DTPA was produced with a spinning disc to ensure a predominantly bronchial deposition of inhaled particles (6.3 microns MMAD). Radioactivity over the chest was recorded with a gamma-camera for 10 min after the subject inhaled the aerosol. Central regions of interest were selected, and the logarithm of the radioactivity was plotted against time; bronchial clearance of 113mIn-DTPA was calculated as the negative slope of the regression line. Clearance was substantially higher in asthmatics during their acute attacks than in all other groups (p less than 0.0001), and it decreased toward normal levels after recovery from the acute episode. The bronchial clearance of 113mIn-DTPA in all other groups did not differ from normal. We conclude that the bronchial clearance of 113mIn-DTPA is increased in asthmatics during attacks of asthma but in the stable state is not related either to bronchial hyperresponsiveness or to airflow limitation. Our findings are best explained by an increase in permeability of the bronchial mucosa of asthmatics during acute attacks.

Acute Disease↗
PubMed1992

Influence of Pneumocystis carinii pneumonia on serum and tissue concentrations of pentamidine administered to rats by tracheal injections.

Pentamidine isethionate was administered by the tracheal route to control rats and immunodepressed rats with Pneumocystis carinii pneumonia (PCP). The serum concentration of pentamidine base 20 min after the administration was higher in the PCP rats (309 +/- 165 ng/ml) than in the control animals (71 +/- 36 mg/ml; p less than 0.001); 90 min after the injection the proportion of the pentamidine administered was lower in the right lung of the PCP rats (29 +/- 15%) than in the control rats (57 +/- 23%; p = 0.038); the proportion of pentamidine in the left kidney was higher in the PCP rats (14 +/- 4%) than in the control animals (4 +/- 2%; p less than 0.001). Respiratory clearance of 99mTc-DTPA, an index of the permeability of the respiratory epithelium, was higher in the PCP rats (1.84 +/- 0.42 %/min) than in the controls (0.44 +/- 0.11 %/min; p less than 0.001). We conclude that the more rapid diffusion of pentamidine from the alveolar lumen to the pulmonary circulation is explained by the increased alveolocapillary permeability as a result of pneumocystosis.

Analysis of Variance↗
PubMed1992

Tachykinins increase respiratory clearance of 99mTc-DTPA. Mechanisms of action.

We investigated the effects of tachykinins on the respiratory clearance of 99mTc-DTPA (RC-DTPA) in anesthetized and ventilated guinea pigs. We measured the change in RC-DTPA and in maximal pulmonary insufflation pressure (PIPmax) induced by substance P, neurokinin A, and capsaicin. Substance P, neurokinin A, and capsaicin increased both PIPmax and RC-DTPA in a concentration-dependent fashion. Substance-P- and capsaicin-induced increases in RC-DTPA were unaffected by pretreatment with atropine. Bilateral vagotomy attenuated substance-P-induced change in both RC-DTPA and PIPmax by approximately 70 and 50%, respectively. Capsaicin-induced change in RC-DTPA and PIPmax were slightly but not significantly reduced by bilateral vagotomy. The bronchodilator, salbutamol, dramatically reduced increase in RC-DTPA and in PIPmax induced by substance P, neurokinin A, and capsaicin, but it had no effect on increases in RC-DTPA and PIPmax generated by application of a positive end-expiratory pressure. We conclude that (1) tachykinins increase respiratory clearance to the solute, and (2) tachykinin-induced increase in RC-DTPA is not mediated by cholinergic neurotransmission but rather by the bronchoconstrictor effect of neuropeptides.

Albuterol↗
PubMed1991

Drug-induced lung disease: 1990 review.

Numerous drug-induced pulmonary manifestations have been reported but studies of their pathogenic mechanisms are still rare. These mechanisms should, however, be precisely determined in order to identify subjects at risk and to prevent some of these complications by the proper use of certain drugs in more appropriate conditions. The possibility of an iatrogenic manifestation should always be considered in patients developing pulmonary symptoms. Data from biological investigations, although not specific, contribute to the understanding of lung injury mechanisms.

Asthma↗
PubMed1991

Effects of tobacco smoke on respiratory epithelial clearance of DTPA and on lung histology in rats.

The respiratory epithelial clearance of 99mTc-(DTPA) diethylenetriamine penta-acetate (RC-DTPA) was measured in rats before and after sham or cigarette smoke exposures. RC-DTPA was increased by cigarette smoke exposure (p less than 0.001); the amount and duration of the exposure had no significant effect. In smoker animals, the number of bronchoalveolar macrophages was decreased after one or five smoke exposures a day for one day (p less than 0.001) and the number of bronchoalveolar neutrophils was increased after five exposures a day for ten days (p less than 0.001). No abnormality was found in the lung parenchyma on light microscopy. We conclude that in rats RC-DTPA is increased by exposure to tobacco smoke, whatever the amount and duration of exposure; however, no gross parenchymal lung abnormality explains the increase in RC-DTPA.

Animals↗
PubMed1990

Effects of inflammation and fibrosis on pulmonary function in diffuse lung fibrosis.

To investigate the relation between lung function and inflammation and fibrosis in patients with diffuse lung fibrosis, a study was made of untreated patients without appreciable airway obstruction (14 patients with cryptogenic fibrosing alveolitis and seven with pneumoconiosis). Quantitative assessment of inflammatory infiltration and fibrosis was carried out on open lung biopsy specimens and compared with lung volumes, carbon monoxide transfer factor (TLCO), TLCO corrected for alveolar volume (TLCO/VA), and arterial blood gases at rest and during exercise. The degree of fibrosis and the degree of cellular infiltration were positively correlated. Lung volumes and TLCO were correlated with the grades of fibrosis and cellular infiltration of alveoli; arterial blood gases during exercise tended to correlate with both fibrosis and infiltration (p less than 0.06). In contrast, morphological data were not correlated with gas exchange at rest or with TLCO/VA. It is concluded that, in untreated patients with diffuse lung fibrosis, lung volumes, TLCO, and arterial blood gases during exercise reflect the lung lesions, and that the pulmonary function tests used cannot discriminate between fibrosis and infiltration of the lung by inflammatory cells.

Adult↗
PubMed1990

Lung function declines in patients with pulmonary sarcoidosis and increased respiratory epithelial permeability to 99mTc-DTPA.

Respiratory epithelial clearance of 99mTc-DTPA (RC-Tc-DTPA) and pulmonary function tests (PFT) were determined at intervals of 6 or 12 months in 37 untreated, nonsmoking patients with sarcoidosis over a period of 6 to 36 months. PFT included the measurements of total lung capacity (TLC), vital capacity (VC), FEV1, and diffusing capacity for carbon monoxide. No difference was found between the respiratory clearance of 113mIn-DTPA (2.25 +/- 1.00%/min) and RC-Tc-DTPA (2.29 +/- 1.11%/min) in eight patients with pulmonary sarcoidosis. Pulmonary function decreased 15% or more in at least 2 function tests during 11 follow-up periods, but it remained stable during 47 follow-up periods. In patients whose lung function deteriorated, RC-Tc-DTPA increased to 3.51 +/- 1.55%/min; in contrast, in patients whose lung function remained stable, regardless of the initial values, RC-Tc-DTPA was normal (1.00 +/- 0.50%/min; p less than 0.001). In eight patients who were treated with corticosteroids, RC-Tc-DTPA decreased from 3.48 +/- 1.31%/min to 1.56 +/- 0.64%/min (p less than 0.001), and PFT improved. We conclude that in nonsmokers with pulmonary sarcoidosis, increased RC-Tc-DTPA is not related to dissociation of 99mTc from DTPA, RC-Tc-DTPA is increased when pulmonary function decreases, and, when increased, RC-Tc-DTPA decreases with corticosteroid therapy.

Adult↗
PubMed1989

Effects of rebreathing conditions and body size on normal human lung tissue volume.

To evaluate the consequences of breathing pattern variations inherent to lung disease on the rebreathing measurement of lung tissue volume (Vt), we carried out a study of ten normal human subjects in whom we assessed the effects of changes in rebreathing volume (Vreb), additional deadspace volume (AVD), respiratory rate (RR), and body height. Vt and alveolar volume (VA) were determined from the end-tidal concentrations of acetylene and helium. We performed Vt measurements using different combinations of Vreb (20, 30 and 50% of predicted vital capacity), of AVD (0, 100, and 200 ml) and of RR (10, 25, and 40 br.min-1). Only slow RR (10 br.min-1) resulted in a higher Vt (p less than 0.001). An increase in Vreb induced an increase in VA but not in Vt. VA and Vt were positively correlated with the height of the subjects. We conclude that, in normal subjects, Vt increases: 1) with the height of subjects; and 2) when the respiratory rate is low. Interpretation of Vt results must take into account these two variables.

Acetylene↗