Influence of mite exposure on symptoms of mite-sensitive patients with asthma.
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Adult↗
Biomedical subjects
J C Bessot
Publications and source records attributed to J C Bessot.
From allergen sources to reduction of allergen exposure.
Allergen exposure plays a major role in the development of sensitization, inflammation and symptomatic asthma. The development of new means of detecting allergens has enabled the evaluation of the effect of a reduction in allergen exposure to be better assessed. In order to prevent allergen exposure it is necessary to determine the allergen sources and reservoirs to which avoidance measures should be directed. The allergen sources and reservoirs of mite, cat, dog, cockroach, rodent, mould and pollen allergens are briefly reviewed. The relationships between allergen exposure, sensitization, nonspecific bronchial hyperreactivity and asthma symptoms are discussed. Recognition of the risks, environmental control, and reduction in allergen loads should be among the objectives of asthma management.
Allergens↗
A double-blind, placebo controlled trial of solidified benzyl benzoate applied in dwellings of asthmatic patients sensitive to mites: clinical efficacy and effect on mite allergens.
BACKGROUND: The aim of this double-blind, randomized study was to investigate the effectiveness of an acaricidal cleaning product in modifying both clinical symptoms and mite allergen levels over a period of at least 1 year. METHODS: Twenty-six asthmatic patients with proven Dermatophagoides pteronyssinus (Dp) asthma were selected; three were withdrawn from the trial. The patients' homes were divided into two groups; 11 homes were treated with solidified benzyl benzoate and tenside agents (A), and 12 were treated with a placebo (P). Two applications were performed at the beginning of the trial and at least 6 months later. Patients were examined 1 month before the trial, at the beginning of the trial, and every 3 months over a period of 1 year. Indoor mite exposure was evaluated by three methods: semiquantitative guanine determinations, quantitative guanine determinations, and the measurement of Der p I + Der f 1 (antigen P, of Dp + antigen F1 of D. farinae) levels. RESULTS: The symptom scores established at the beginning of the trial and 12 months later showed a statistically significant improvement only in the A group (p < 0.01). The visual analog scale also showed a statistically significant difference both in the A (p < 0.05) and P groups (p < 0.01). No statistical differences were found between medication scores in the A or P groups. A statistically significant increase was also observed for forced expiratory volume in 1 second and maximal expiratory flow rate 25/75 in the two groups (p < 0.05 for P group; p < 0.01 for A group). The mean decreases in Der p I + Der f 1 in patient mattresses between the beginning of the trial and after 12 months were 20% for the acaricide group and 17% for the placebo group, respectively (NS). For house dust samples with origins other than the patients' mattresses we found significant decreases in Der p I+Der f 1 in the A group (p < 0.01 for carpets and p < 0.05 for upholstery elements).
Adolescent↗
Mite allergen content in mattress dust of Dermatophagoides-allergic asthmatics/rhinitics and matched controls.
It has been suggested that the mites Dermatophagoides pteronyssinus and D. farinae are important indoor environmental factors facilitating both the sensitization of atopic subjects and asthmatic attacks of house dust-sensitive patients. Contradictory results have been reported about the current exposure to mites or their allergens among patients and control groups of atopic or non-atopic subjects. In order to determine whether there is a difference in mite exposure levels between D. pteronyssinus-sensitized asthmatics and/or rhinitis and control subjects we considered a case-control study of 70 patients with asthma and/or rhinitis and positive skin test reactions to D. pteronyssinus and twice as many control subjects who were matched as to age and sex. The first control subject for each patient was an immediate neighbour of the patient and the second was patient arbitrarily chosen among hospitalized patients. Mite allergen exposure was measured in mattress dust collected under standardized conditions, by measuring Der p I+Der fI content and by performing a semiquantitative guanine determination (Acarex-test). The content of Der p I and Der fI was very high both in the homes of patients and those of healthy individuals: 69% of the total samples contained more than 10 micrograms Der pI+Der fI/g of dust. There was no significant difference between cases and controls with respect to Der p I, Der fI, Der p I+Der fI content and Acare class distributions. The calculated odds-ratios associated with the Acarex test and the mite allergens did not differ significantly from the level 1.0.(ABSTRACT TRUNCATED AT 250 WORDS)
Adolescent↗
Protective effect of nedocromil sodium on the dual asthmatic response to bronchial antigen challenge.
The effects of nedocromil sodium and placebo on the asthmatic response to antigen bronchial provocation were studied in a double-blind, randomized, crossover trial. Twelve subjects sensitized to Dermatophagoides pteronyssinus were challenged with successive doubling doses of this allergen (1.25-80 x 10(-3) mg) on two separate occasions, at least 15 days apart. A single dose of either nedocromil sodium 4 mg, or, a matching placebo was given 30 min before challenge. Forced expiratory volume in 1 s (FEV1) was measured 5, 10 and 15 min after challenge. Early asthmatic response was analyzed using three indices: dose producing a 20% decrease in FEV1 (PD20), the slope of and area under the dose-response curve. Nedocromil sodium was significantly superior to placebo with respect to all three indices, providing significant inhibition of the early asthmatic responses. Seven of the 12 patients showed a late asthmatic response. There was no significant difference between the effects of nedocromil sodium and placebo treatments on the decline in peak expiratory flow rate (PEFR) during the late asthmatic response but it should be noted that when patients had been treated with nedocromil sodium they were receiving two to eight times the dose of allergen given after placebo treatment.
Adult↗
[Occupational asthma: an experimental asthma. Apropos of isocyanate-induced asthma].
Isocyanate-induced occupational asthma is a model of experimental asthma related to the environment. Many of its features are identical with those of allergic asthma by sensitization to air-borne allergens. Exposure to isocyanate before the first symptoms of asthma varies from a few weeks to several years. The prevalence of isocyanate-induced asthma has been estimated at 5 to 25%. Atopy is found in less than 30% of the cases. A significant increase of HRBNS can be demonstrated in most patients, but it may be absent. It may also fluctuate with the working periods or after a bronchial provocation test with isocyanate. Elimination of this compound reduces the HRBNS level in only one quarter of the cases. Delayed or biphasic reactions are frequent: 30 to 60% depending of the authors. An early diagnosis followed by total elimination may result in complete cure, but more than 50% of the patients remain symptomatic and with HRBNS. An IgE-dependent mechanism can be demonstrated in about 20% of the cases. The course of isocyanate-induced asthma is interesting in that the same phenomena are probably observed in chronic asthma resulting from repeated exposures to environmental allergens.
Asthma↗
[Pollution in the home interior and asthma].
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Air Pollution, Indoor↗
[The pertinence of bronchial provocation tests to allergens].
The contribution and the relevance of bronchial provocation tests to allergens have been evaluated in the realm of clinical research and in the diagnosis of the aetiology of asthma. These tests enable the recognition or to confirm the role of certain allergens in asthma, as well as to study the delayed reaction which occurs in some cases after the inhalation of an allergen as well as the relations existing between HRBNS and bronchial provocation tests to allergens. They also can show the preventative action of certain drugs on the immediate and/or delayed reaction induced by allergens. The methodology of bronchial provocation tests to allergens, notably their variability and their reproductibility, as well as the initial and maximal inhaled doses that can be realistically used, are discussed. The final point touched upon concerns the justification of bronchial provocation tests to allergens in the aetiological diagnosis of asthma. The indications of these tests have been restricted, they seen nonetheless always to be of interest in cases of discordance with the clinical history, cutaneous tests and/or measures of specific serum IgE.
Allergens↗
[Prevention of asthma caused by dust mites].
The house-dust mites are responsible for the majority of allergic asthma. It is currently possible to measure the exposure to their allergens, and this allows for a better guide as to the indications for eviction measures; there is also a more objective appreciation of the efficacy of these measures. A decrease in the relative humidity of the interior of the house effectively hinders the proliferation of the mites. Vacuuming the room, notably the mattress, is not sufficient in the majority of cases to reduce the level of allergenicity of the mites to a tolerable level for the asthmatic patient. Thus, it is necessary to renew the bedding, or to hermetically seal the mattress in a plastic cover. Washing the bedding at a temperature above 55 degrees C will kill the mites. Amongst the chemicals available in the struggle to reduce the mite population, the acaricides lead to an elimination of 65-100% of the mites in a mite culture. Tannic acid, which is a protein de-naturing agent, can reduce the allergenicity of the house-dust. Certain control studies related to the effect of the acaricides demonstrate an improvement in objective and subjective parameters of both asthma and rhinitis due to mites. However, the efficacy of these acaricides, as well as measures to clean up the environment within the house, merit more precise evaluation on the symptomatology, the changes of expiratory flow rates, and finally of broncho-reactivity in patients. It is probable that several preventative measures need to be associated if one wishes to improve the efficacy of the struggle to control the house-dust mites.
Animals↗
[Occupational asthma].
The diagnosis of occupational asthma requires the integration of a multiplicity of data; the history, cutaneous skin tests, biological tests, respiratory function tests and non-specific tests of bronchial hyperreactivity and specific bronchial provocation test. The history search for the presence of an atopic state, the occurrence of similar disorders in members of the same firm and also the timing of symptoms in relation to the occupational activities. Cutaneous tests are particularly helpful in IgE-mediated asthma in relation to the inhalation of animal or vegetable materials of glycoprotein origin. For haptens, the need for their prior coupling to a protein carrier causes problems which have not been entirely resolved. Laboratory tests run into the same snags. Respiratory function and non-specific bronchial provocation tests, confirm the diagnosis of asthma and enable the medium and long term prognostic to be assessed. Specific bronchial provocation tests are the most appropriate tests to establish an aetiological diagnosis in occupational asthma. Different technical methods are possible: quantitative administration of allergen aerosols, realistic tests, and tests using exposure chambers to achieve true test doses. The products responsible for occupational asthma are multiple. The different substances are characterised in a simplified manner: first animal matter (mammalian and arthropod allergens), secondly substances of vegetable origin (roots, leaves, flowers, grain and flour, wood and its derivates) and finally chemical products. The chemical products are primarily from the pharmaceutical and metal industries and above all from the plastics industry.
Allergens↗
[Occupational asthma caused by ebony wood].
A case of occupational asthma to ebony wood dust is described in a violin and stringed instrument maker, who was sanding and filing ebony to make the finger boards of violins and cellos. The diagnosis was confirmed using a realistic provocation test; after sanding and smoothing the ebony for 20 minutes the patient developed bronchial spasm with fall of the force expired volume in one second (VMS) of 45% which was reversible following the inhalation of beta 2 agonists. A delayed reaction was seen at 3 hours and 6 hours and at 20 hours after the test. The observations of occupational asthma or rhinitis to ebony wood are very rare. To our knowledge there are two publications at the present time. It has been recognised as an occupational disease (see table 47 of occupational diseases) and an exclusion order has been effected.
Adult↗
Comparison between Der p I plus Der f I content determinations and guanine measurements in 239 house dust samples.
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Air Pollutants↗
[Asthma due to isocyanates in a theoretically non-exposed worker].
We report a case of isocyanate induced asthma in a patient who had been previously exposed to isocyanate and had become a porter in a factory producing polyurethene foam. The test for exposure to TDI was positive. The recognition of occupational asthma was nevertheless challenged and the patient was not considered to be carrying out work involving exposure to the inhalation of isocyanates. The effect of a change of job in the development of occupational asthma, and the risk of asthma induced by isocyanates despite inhaled concentrations inferior to the VME, the difficulty of obtaining a recognition of occupational asthma when the working conditions fulfilled do not exactly correspond to those labelled in the schedule for occupational diseases, are discussed in this paper.
Adult↗
[Asthma, reaginic allergy and bronchial hyperreactivity].
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Asthma↗
[Localization of acari allergens in the home using the guanine test].
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Acari↗
Platelet function: aggregation by PAF or sequestration in lung is not modified during immediate or late allergen-induced bronchospasm in man.
Among the mediators involved in the pathophysiologic mechanisms that underly the reactions of the acute and delayed phases of bronchospasm induced by allergens in man, platelet-activating factor (PAF) could play an important role, in particular by its effects on platelets. In animals, inhalation or injection of PAF causes a platelet-dependent bronchoconstriction that is blocked by prior administration of an antiplatelet antiserum and accompanied by platelet accumulation in the pulmonary vessels. In man, inhalation of PAF causes a bronchospasm and induces a bronchial hyperreactivity. Abnormalities of platelet aggregation and the secretion into plasma of platelet factor 4 and beta-thromboglobulin have been described in patients with asthma during induced bronchospasm. Platelet functions have been studied in 15 patients with asthma before and after allergen bronchial provocation tests. There was no difference between platelet counts, plasma concentrations of platelet factor 4 and beta-thromboglobulin, and platelet aggregation induced by several agonists (adrenaline, arachidonic acid, or PAF) before and immediately after the allergen bronchial provocation test. There was no platelet pulmonary sequestration as studied with 111Indium-labeled platelets during 24 hours after the antigen challenge, and the life span of circulating platelets was normal. Our results do not support an important direct role for PAF in the pathophysiology of asthma. It is still possible that the current methodology is too insensitive to detect amounts of PAF in the circulation or that PAF is acting locally.
Adolescent↗
[Effect of the environment on the development of respiratory allergies].
Allergy reactions may be regarded as resulting from exposure to allergens of subjects who are genetically predisposed to synthesize IgE. The presence of allergens in the environment is necessary to acquire sensitization. With some allergens, sensitization seems to develop very rapidly. The introduction or presence in the environment of certain allergens, such as house dust mites, may increase the prevalence of asthma. Despite conflicting reports, in atopic subjects exposure to pet animals also is a risk factor. Introducing foreign proteins prematurely into infant's food has been considered a factor that facilitates the development of allergic diseases. Contact with occupational allergens results in allergic manifestations in less than one-third of the subjects exposed, which suggests that genetic factors play a predisposing role. Beside exposure to allergens, non-specific environmental factors, such as chronic inhalation of tobacco smoke or atmospheric pollutants (e.g. ozone, SO2, NO2, particles of burnt fuels) might contribute to sensitization. The part played by viral infections (RSV or influenza virus) in the triggering of allergic diseases has often been reported. Interactions between irritants and allergens may encourage the development of respiratory allergy.
Acari↗
Guanine and mite allergenicity in house dust.
Guanine is the major nitrogenous waste product in arachnids. It may serve as an indicator for allergenic mite faecal pellets. The present study assesses the correlation between the mit allergenicity of different house dust (HD) samples and their guanine content. Guanine content in HD samples was evaluated either by the Acarex-Test or determined quantitatively, especially for in-vitro methods. Using intradermal tests in selectively sensitized Dermatophagoides pteronyssinus (Dpt) patients, we evaluated the mite allergenicity of eight extracts obtained from HD samples with varying guanine contents. The weal area appeared to be proportional to the HD samples' guanine content. A three-fold increase in skin reactivity was observed when the guanine content varied from 0.06% to more than 1%. Patients allergic to HD but not to Dpt had no significant reactions with HD extract prepared from a guanine-rich HD sample. For eighteen different HD samples coupled to paper discs, the percentage Dpt RAST binding values obtained with a Dpt-selectively sensitized patient serum pool was correlated with the guanine concentrations of HD samples (P less than 0.01). The potencies of different HD extracts obtained from HD samples that varied in guanine content were also clearly distinguished on histamine-release titration curves. House dust obtained from homes at high altitude or from hospitals was generally guanine free. The HD sample guanine contents in homes where twelve Dpt-sensitized patients experienced symptoms were significantly higher than in homes where these patients were symptom free. The guanine colour test, a quick and easy technique, represents an important new development in indoor environmental investigations. It makes it possible to demonstrate mite faecal exposure and can be used to monitor the effectiveness of mite allergen avoidance measures.
Allergens↗