Search PubMed⌕ Search

Biomedical subjects

F de Blay

Publications and source records attributed to F de Blay.

At least 19 recordsLinked to original sources
PubMed2006

Low-dose endotoxin in allergic asthmatics: effect on bronchial and inflammatory response to cat allergen.

BACKGROUND: Endotoxin was proposed to increase the severity of asthma. Endotoxin levels greatly differ according to settings. In domestic environments, airborne concentrations may be dramatically low compared with levels reported in occupational settings. OBJECTIVE: Our first objective was therefore to assess the effect of inhalation of low-level lipopolysaccharide (LPS) on the immediate and late-phase asthmatic bronchial response. Our second objective was to evaluate the effect of exposure to LPS on the local and systemic inflammatory response. METHODS: Nineteen asthmatics sensitized to cat underwent on two separate occasions a bronchial challenge test to cat allergen (cat BCT) preceded randomly by a pre-exposure to either saline or LPS (2 microg). Methacholine challenge test was performed 24 h before exposure to LPS or saline. The Borg scale for dyspnoea and lung function were recorded before and after exposure to LPS or saline, and before and after cat BCT. Induced sputum and blood samples were collected before and after cat BCT, and analysed for cell counts and eosinophil cationic protein (ECP) levels. RESULTS: Inhalation of 2 microg LPS did not induce any changes in forced expiratory volume in 1 s (FEV1), peak expiratory flow (PEF), FEF 25-75 and Borg scale of dyspnoea. It neither modified Fel d 1 PD20 (45.03 ng as compared with 87.03; P=0.42). As well, there was no significant difference in late-phase reaction. Pre-exposure to LPS did not influence eosinophil counts or ECP levels in blood and sputum. CONCLUSION: Our study demonstrated that pre-exposure to LPS at low levels, which may be encountered in domestic environment, had no significant effect on the immediate and late-phase bronchial response to cat allergen. It neither modified local and systemic eosinophilic inflammation.

Adult↗
PubMed2006

Inhaled formaldehyde exposure: effect on bronchial response to mite allergen in sensitized asthma patients.

BACKGROUND: Formaldehyde, an indoor air pollutant, is known to be an irritant and an etiologic factor in occupational asthma. An epidemiologic study suggests that it may also increase the risk of childhood asthma for concentrations above 60 microg/m(3). AIM: To evaluate the influence of pre-exposure to low-dose formaldehyde (100 microg/m(3) in 30 min according to the World Health Organization's recommended maximum value for indoor environments) on bronchial response to Dermatophagoides pteronyssinus. METHOD: Nineteen asthmatic subjects were included. Each subject underwent a mite allergen bronchial challenge test immediately after a standardized exposure in a chamber to formaldehyde or air (random order). Induced sputum were collected 24 h before and after mite challenge. RESULTS: After formaldehyde inhalation, patients developed an immediate bronchial response at a significantly lower dose of mite allergen than after air exposure (the geometric mean PD(20) for Der p 1 was 34.3 ng after formaldehyde and 45.4 ng after placebo, P = 0.05). The late-phase reaction, expressed as the maximum fall in forced expiratory volume in 1 s (FEV(1)) from baseline, was significantly higher after formaldehyde (15%vs 11%, P = 0.046). CONCLUSION: Our study demonstrated that exposure to low levels of formaldehyde significantly enhanced bronchial responsiveness to mite allergen in mite-sensitized subjects with asthma.

Adult↗
PubMed2006

[The bronchial response to inhaled formaldehyde].

INTRODUCTION: Formaldehyde is an ubiquitous indoor chemical polutant. Occupational exposure to high concentrations has revealed its irritant and allergenic potential. Nevertheless, domestic exposure to low concentrations may also have an effect on respiratory health in a non-specific way, just as has been found for other pollutants. STATE OF KNOWLEDGE: Potentiation of the response to allergens has been observed in animals and children. This effect has also been found on respiratory symptoms, with a 39% increase in the risk of asthma for a domiciliary exposure of more than 60 microgrammes.m(-3). We have recently been able to show, in a study with asthmatics sensitised to house dust mite, that the response to allergen provocation was increased following a 30 minutes exposure to 100 microgrammes.m(-3) formaldehyde. VIEWPOINT AND CONCLUSIONS: All the data show that mild exposure to formaldehyde in the home is sufficient to provoke sensitisation and also an aggrevation of symptoms in patients with allergic asthma. Taking into account the published evidence it is advisable that the concentrations of formaldehyde in domestic products should be made known in order to improve domiciliary air quality.

Air Pollution, Indoor↗
PubMed2005

[Markers of environmental tobacco smoke (ETS) exposure].

INTRODUCTION: Tobacco smoke is one of the most common air pollutants found in the indoor environment. Passive smoking is defined as the involuntary inhalation of tobacco smoke present in the air. This article examines the advantages and limitations of the methods that are available to measure environmental tobacco smoke exposure. STATE OF THE ART: Passive smoking can be assessed either by measuring tobacco smoke pollutants found in the air directly or by using biomarker assays, an indirect measure of exposure. CONCLUSION: As far as the direct measurement of air pollutants is concerned, nicotine and 3-Ethenylpyridine levels seem most suitable because of their specificity. Four specific biological markers of tobacco smoke exposure are available: nicotine, cotinine, thiocyanates, and protein or DNA adducts. Only urinary cotinine assay can be retained as a reliable marker of exposure to tobacco smoke. It has been used as a reference in most epidemiological studies but only reflects tobacco exposure over the preceding 48 hours. The measurement of nicotine and cotinine levels in the appendages of the skin (hair and nails) reflects exposure to tobacco over the previous three months and could become a better reference marker in epidemiological and toxicological studies.

Cotinine↗
PubMed2005

[Allergic fungal sinusitis and allergic broncho-pulmonary aspergillosis: a fortuitous association or a nosological rhino-bronchial entity?].

INTRODUCTION: The identification of allergic fungal sinusitis (AFS) is much more recent than that of allergic broncho-pulmonary aspergillosis (ABPA) and may still be incomplete and controversial. Their association has been only rarely reported in the literature. Is it a matter of a fortuitous association or of a well defined and/or new nosological rhino-bronchial entity? METHODS: A retrospective study was undertaken from a series of 10 cases of AFS with 4 cases associated with ABPA and fulfilling all the diagnostic criteria described in the literature. RESULTS: The association of AFS and ABPA may be concomitant (2 cases) or not (2 cases) with a possible time lag of several years between the onset of naso-sinal and broncho-pulmonary disease, even after recovery from the original episode. Treatment comprising steroids, endoscopic surgery (4 cases) combined with anti-fungal drugs (2 cases), led to resolution (2 cases), a considerable improvement (1 case) and therapeutic failure in 1 case (follow up longer than 4 years in all cases). CONCLUSION: The association, concomitant or remote in time, of AFS and ABPA emphasises the unity of the upper and lower airways as well as the pathophysiological relationship between these two fungal respiratory diseases. The prevalence of this association remains low and the treatment is not standardised.

Adult↗
PubMed2005

[IgE and respiratory disease].

INTRODUCTION: IgE is known to provide the biological basis for allergy and immediate hypersensitivity. However, recent data provide some evidence that IgE responses are involved in other inflammatory processes apart from allergy, including several respiratory diseases. STATE OF THE ART: IgE binds to mast cells and basophils but also to other inflammatory cells, which are involved in non-allergic processes. IgE has a role in antigen presentation and is implicated in a number of other immune mechanisms. In the airways, IgE plays an important role in bronchial hyperactivity, even in the absence of an allergen. Epidemiological studies have demonstrated that IgE response is related not only to allergy but also to asthma symptoms, in the presence or absence of atopy, as well as exposure to cigarette smoke. IgE response is altered in several respiratory diseases including extrinsic and intrinsic asthma and allergic bronchopulmonary aspergillosis. CONCLUSION AND PERSPECTIVES: Since anti-IgE monoclonal antibodies are now available for administration to humans, a better understanding of the IgE response may allow the identification of novel therapeutic targets in the field of respiratory disease.

Adolescent↗
PubMed2004

[Pharmacists' role in the management of asthma: a survey of 120 pharmacists in Bas-Rhin].

INTRODUCTION: The pharmacist plays an essential role in the management of the asthmatic patients on account of their frequent visits to the pharmacy to obtain their medication. METHODS: In order to evaluate the practice and knowledge of asthma among the pharmacists of the department of Bas-Rhin, 120 pharmacists were selected at random to reply to a standardised questionnaire. RESULTS: The 86 pharmacists who replied to the questionnaire had a good general understanding of asthma and its treatment. However, only 26.4% knew all the criteria of the severity of an attack of asthma. Among the 57 pharmacists who gave a demonstration of the use of inhaler devices, 16.3% showed all the steps in the use of a metered dose aerosol. These results are comparable to those of non-specialist doctors and nurses in whom poor techniques were found in 63-100% and 65-96% respectively. The mean scores of the pharmacists were 10.5/12 (+/- 1.2) steps for metered dose aerosols, 10.4/11 (+/- 1.0) for the Tubuhaler, 9.3/12 (+/- 1.7) for the Autohaler and 8.1/9 (+/- 0.9) for the Volumatic spacer. The asthmatic patient's main expectation of the pharmacist concerned the use of the prescribed systems (87.2%), underlining the lack of information received by the patient at the time of prescription. CONCLUSIONS: An improvement in the knowledge of the signs of severity of asthma and the use of inhaled devices could usefully be one of the objectives in the training of a dispensing pharmacist.

Adult↗
PubMed2004

Dose-dependent effects of endotoxins on allergen sensitization and challenge in the mouse.

BACKGROUND: Levels of endotoxins greatly differ according to environmental settings. OBJECTIVE: To study the effect of lipopolysaccharide (LPS) at increasing doses (0.1-1000 ng) on allergen sensitization and challenge in the mouse. METHODS: Mice were sensitized systemically and challenged locally with ovalbumin (OVA) in the presence or absence of LPS. Inflammation was assessed by determining total and differential cell counts and T-helper type 2 (Th)2 cytokine (IL-4 and IL-5) levels in bronchoalveolar lavage fluid (BALF). Total and OVA-specific IgE levels were quantified in serum. Airway hyper-responsiveness (AHR) was assessed by whole-body barometric plethysmography. RESULTS: Administered prior to sensitization, LPS at 100 or 1000 ng dose-dependently decreased allergen- induced total and OVA-specific IgE, airway eosinophilia and Th2 cytokines in BALF, without changing AHR. Administered during OVA challenge, LPS at 1 ng (an infra-clinical dose) or 100 ng (a dose triggering neutrophilia) enhanced airway eosinophilia, without affecting IgE levels or AHR. CONCLUSION: Our data clearly demonstrate that exposure to LPS influences allergen-induced IgE production and airway eosinophilia in a time and dose-dependent manner, preventing IgE production and development of eosinophilia when administered during allergen sensitization at high doses, and inducing exacerbation of eosinophilia when administered upon allergen challenge at low doses, including infra-clinical doses.

Allergens↗
PubMed2003

Medical Indoor Environment Counselor (MIEC): role in compliance with advice on mite allergen avoidance and on mite allergen exposure.

BACKGROUND: In order to improve patient compliance in allergen avoidance, a new occupational activity was created: Medical Indoor Environment Counselor (MIEC). The aim of this study was to assess the impact of an MIEC on compliance with advice for mite allergen reduction in patients sensitized and exposed to mite allergens, and on mite allergen levels. METHODS: The study included 378 patients from four centers (Marseilles, Montpellier, Paris, Strasbourg) in a randomized prospective study. Patients in group A received advice from doctors only, and those in group B from doctors and MIEC. Mite allergen levels were measured on mattresses, mattress bases, and floors. Compliance and mite allergen levels were assessed 5 months later. RESULTS: Compliance for changing the mattress bases, removing or treating the carpets, washing duvets, pillows and stuffed animals were significantly higher in group B than in group A. A significant decrease in mite allergen was obtained for group B in mattress bases (83.8-22.9 micro g/g) and in carpets (15.8-6.3 micro g/g), but not in group A. CONCLUSION: Our results suggest that the home visit by the MIEC 1) increased the compliance to mite reduction methods advised; 2) induced a significant difference in mite reduction levels on mattress bases and on carpets; 3) avoided nonestablished avoidance advice.

Adolescent↗
PubMed2002

Nerve growth factor levels and localisation in human asthmatic bronchi.

Nerve growth factor (NGF) has recently been suggested to be an important mediator of inflammation. In support of this, serum levels of NGF have been shown to be enhanced in asthmatics. However, it has not yet been shown whether the levels of NGF are also altered locally in asthmatic airways, when compared with healthy subjects, and the localisation of potential sources of NGF in the human bronchus have not yet been described. The aim of the present study was to assess NGF levels in bronchoalveolar lavage fluid (BALF) from asthmatics and to compare them to those of control subjects. Furthermore, the authors wanted to localise potential sources of NGF in bronchial tissue, and to number NGF-immunopositive infiltrating cells in the bronchial submucosa. BALF and bronchial biopsies were obtained from seven control subjects and seven asthmatic patients by fibreoptic bronchoscopy. NGF protein levels were quantified by enzyme-linked immunosorbent assay in BALF. NGF localisation was examined by immunohistochemistry on bronchial biopsy sections. The asthmatics exhibited significantly enhanced NGF levels in BALF. Intense NGF-immunoreactivity was observed in bronchial epithelium, smooth muscle cells and infiltrating inflammatory cells in the submucosa, and to a lesser extent in the connective tissue. The asthmatics exhibited a higher number of NGF-immunoreactive infiltrating cells in the bronchial submucosa than control subjects. This study provides evidence that nerve growth factor is locally produced in the airways, and shows that this production is enhanced in asthmatics. These findings suggest that nerve growth factor is produced by both structural cells and infiltrating inflammatory cells in human bronchus in vivo, and the authors suggest that the increase in nerve growth factor protein in bronchoalveolar lavage fluid observed in asthmatic patients may originate both from structural cells, producing increased nerve growth factor levels in inflammatory conditons, and from the increase in nerve growth factor-immunopositive cells determined in the bronchial submucosa.

Adult↗
PubMed2001

Local increase in the number of mast cells and expression of nerve growth factor in the bronchus of asthmatic patients after repeated inhalation of allergen at low-dose.

BACKGROUND: Repeated inhalation of allergen at low-dose induces an increase in bronchial hyper-responsiveness, without any associated symptom. The concomitant events in the bronchus have not been described. OBJECTIVE: We have studied the dynamic number of mast cells in the airways of patients with mild asthma before and after repeated inhalation of allergen at low-dose and the expression of nerve growth factor (NGF), which is reported to promote growth and survival of mast cells. METHODS: Twelve patients with mild asthma to cat allergen were enrolled at random in a blind placebo-controlled study, and submitted to repeated low-dose allergen exposure (1/5 of the provocative dose). Mast cells were immunolocalized using an antibody against mast cell tryptase. NGF and its high affinity receptor, TrkA, were immunolocalized using anti-NGF and anti-TrkA antibodies, respectively. NGF mRNA was quantified by competitive polymerase chain reaction (PCR) after reverse transcription of total RNA extracted from bronchial biopsy. NGF protein levels were measured by ELISA in bronchoalveolar lavage (BAL) fluid. RESULTS: Bronchial mast cell number was increased significantly after allergen exposure as compared with before. NGF expression in the bronchus was immunolocalized mainly to epithelial cells, but also to fibroblasts, blood vessels, and a few infiltrated cells. NGF mRNA levels in bronchial biopsies were increased significantly after allergen exposure. The high affinity receptor for NGF, TrkA, was immunolocalized to the infiltrated mast cell membrane. CONCLUSION: Our study shows that the increase in the number of mast cells and in the expression of NGF induced by allergen exposure in the bronchus of asthmatic patients is occurring before the onset of symptoms. In addition, our finding of the presence of the TrkA receptor on the membrane of the infiltrated mast cell in situ brings evidence of the mast cell as a target cell for the growth factor activity of NGF in the airways in asthma.

Administration, Inhalation↗
PubMed2001

Difference in exposure to airborne major rat allergen (Rat n 1) and to endotoxin in rat quarters according to tasks.

UNLABELLED: Endotoxins found in occupational settings constitute a risk factor in the severity of respiratory allergic symptoms. OBJECTIVES: To assess the airborne concentrations of major rat allergen (Rat n 1) and endotoxin under various circumstances. METHODS: We took 483 airborne samples from 12 sites: 114 individual samples for endotoxin measurements and 113 for Rat n 1, from 38 workers (nine animal technicians, nine laboratory technicians, nine scientists and 11 students); and 256 static samples in rat rooms and experimental rooms, with or without disturbance, for simultaneous endotoxin and Rat n 1 measurements. Rat n 1 was measured with a two-site monoclonal ELISA and endotoxins with the Limulus method. RESULTS: Airborne Rat n 1 and endotoxin were significantly higher in rat rooms than in experimental rooms. Animal technicians had the greatest exposure to both Rat n 1 and endotoxin. Cage cleaning and rat feeding induced the highest exposure to Rat n 1 and endotoxin. Furthermore, we observed no significant difference in endotoxin exposure between researchers with or without rat contact during the sample period. There was no correlation between the number of rats present and airborne endotoxin concentrations. CONCLUSIONS: Exposure to airborne Rat n 1 and endotoxin is higher during cleaning and feeding tasks than during any other task, we feel that a major source of both is contaminated bedding that becomes airborne during disturbance.

Air Pollutants, Occupational↗