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Biomedical subjects

M Thibaudon

Publications and source records attributed to M Thibaudon.

29 records · Page 2Linked to original sources
PubMed1997

[Association between air pollen concentrations and seasonal allergies: synthesis of epidemiological studies published between 1978 and 1995].

Many clinical studies have shown a causal link between exposure to pollens and clinical symptoms of atopy. However knowledge regarding the dose-response relationship between airborne pollen counts and the occurrence of clinical symptoms of seasonal pollinosis in the population, are not well known. The review of epidemiological studies published in this field for the last 15 years indicates that most epidemiological studies were carried out using a panel study design of well documented pollinosis subjects. These studies aim at estimating the correlation between daily airborne pollen counts measured by an aeropollinic surveillance network and clinical indicators characterising the health condition of the studied population. Nevertheless, because of many methodological weaknesses, especially regarding the methods of statistical analysis, the results of these studies do not allow to conclude that there is a short term association between airborne pollen counts and the incidence of symptoms of seasonal pollinosis. This field of research is a priority in order to assess the public health impact of pollens, and to use with efficacy the data collected by monitoring networks.

Air Pollutants↗
PubMed1997

[Pollen environment and its evaluation].

We review the methods available for determining airborne pollen. In addition to the classical gravimetric and volumetric methods, new immunochemical techniques are also used for detecting allergenic pollen and measuring of the size of allergen-carrying particles. Pollen counts are available in France for 39 urban sites. In the last decade changes in the pollen environment have basically concerned higher counts from resinous trees in southern France and birch tree counts in northern France as well as a lesser role for ash trees. Among the recent acquisitions, it has been demonstrated that allergens are present in twigs and leaves, or even the bark of certain trees. Interactions with atmospheric pollution is better understood and could be a contributing factor to the increasing number of people allergic to pollen. Pollen allergens can be carried on particles of various sizes and immunochemical studies have demonstrated that gramineous pollen allergens can be carried on starch particles less than 3 mu in diameter. These recent studies would explain the apparent disagreement between pollen counts and the number of clinical manifestations.

Air Pollutants↗
PubMed1992

[Spatial and temporal variations of the quantities of pollen from Cupressaceae-Taxaceae collected in Marseilles].

Marseille has two sites (Centre and North) where airborne pollens are collected and counted. The most numerous pollens are from Cupressaceae Taxaceae. We compared the quantities collected with both pollen traps during February, March and April 1988 and 1989. Most of pollinization takes place in March. In Marseille's Centre, there were three times more trapped pollen during 1989 than in 1988. In 1989, there was 40% more pollen on northern site as compared with the other one. As indicated in 1989 with both sites, it suggests a circadian periodicity of Cupressaceae Taxaceae pollen: their highest count is usually between 9 and 11 hours a.m.

Air↗
PubMed1992

[Ragweed in France; some air pollen data for the years 1987-1990].

The permanent recording of air pollen contain from more than 25 sites distributed all over France using the same method gives homogeneous results with every two hours daily measures. Among usual pollen taxa harvested in the city of Lyon, Ambrosia pollen data is to be emphasized due to its high allergenic potency. Between years 1987 and 1990, Ambrosia pollen data observed in Lyon have been recorded and completed with data obtained from other places in France where Ambrosia is also to be found during the summer and autumn seasons. Significant annual variations have been observed while the daily repartition of records appear quite steady. Data obtained do emphasize the high allergenic potency of Ambrosia of air pollen origin in a great number of french regions.

Air↗
PubMed1990

Bronchial challenge to house dust can induce immediate bronchoconstriction in allergic asthmatic patients.

The goal of the study was to evaluate whether natural exposure to house dust could elicit immediate bronchoconstriction. Two groups of asthmatic patients were studied: 12 asthmatics allergic to house dust mites and seven nonallergic asthmatics. The baseline FEV1 was similar in the two groups. Each subject was challenged through a nasal mask connected to nebulizer filled with house dust. Patients were randomly assigned to inhale dust with high or low Group I allergenic level. All allergic patients had an FEV1 drop larger than 20% of the baseline value. This drop was maximal at the 30th minute after challenge. FEV1 remained unchanged in nonallergic asthmatics. Allergic patients challenged with high Group I allergenic house dust (8.4 micrograms/g) had a mean FEV1 drop larger (P less than .01) than those challenged with the low Group I allergenic house dust (0.66 micrograms/g). Late asthmatic reactions were found in only two patients who were challenged with the high Group I allergenic house dust. These two patients had immediate FEV1 drops greater than 50% of the baseline value. Occurrence of symptoms during the test and the drop in FEV1 were correlated (r = .3; P less than .05). Natural exposure to house dust can induce immediate bronchial in allergic asthmatics in a dose-dependent manner.

Adult↗
PubMed1989

[Is it necessary to test children having summer respiratory problems with cereal pollens?].

We tested 100 children with clinical signs that occurred in spring or summer. Prick tests were made with extracts of wild grass pollens (Dactylis, Phleum, Lolium) and with separate cereal pollens (Wheat, oats, Sweet-corn Barley and Rye). In 20 children whose test was negative for wild grass pollen, we saw no sensitization to cereals. In 80 children with grass pollenosis, Barley and Rye are the cereals that gave the most positive prick tests, whilst sweet corn is the cereal with most negative tests.

Allergens↗
PubMed1988

[Comparative study of 3 positive controls for routine prick tests in children: 48/80, 1 mg histamine and 5 mg histamine].

We compared, among 153 children 2 to 14 years old, responses to some positive control solutions for prick tests made with a Stallerpoint. We obtained the following values: -6% - 48/80:4.46 +/- 1.88 mm -1 mg/ml Histamine:3.49 +/- 1.67 mm -5 mg/ml Histamine:5.13 +/- 1.78 mm. 1 mg/ml histamine gives too many null responses (12/153) to represent a valuable positive control. 5 mg/ml histamine, on the other hand, gives some very strong reactions which may induce an underestimation of responses to allergen tests. Compound 48/80 seems to remain the best positive control for prick test exploration of immediate allergy in children. An alternative might be an intermediate solution of histamine 2.5 mg/ml.

Adolescent↗
PubMed1988

[Specific desensitization with allergen extracts absorbed on calcium phosphate (Pasteur Institute). Clinical and biological study apropos of 107 cases].

107 allergic patients (71 children and 36 adults) were desensitized with allergen extracts adsorbed on calcium phosphate. Patients were selected following their symptoms (asthma, rhinitis, juvenile bronchitis, pollinosis), skin tests (ID or Prick) and total or specific IgE levels (PRIST and RAST). A mean of 17 month treatment, usually with house dust and mite extracts, rarely with house dust extract alone and in 6 cases with a mixture of grass and cereal pollens. The major aim of this study was to test the immunotherapy efficiency and to compare the IgE level variations and the clinical results. The treatment was found very good in 62% of the cases, good in 28%, and negative in 10% of the cases. The mean total IgE level has decreased of 58%, and the specific IgE level has decreased in 77% of the patients. The number of patients with a RAST class O to house dust and mites has increased respectively of 23% and 24.4% after the treatment. Besides some very good cases where the IgE levels have dropped there are lew relations between the total or specific IgE antibodies and the clinical results. The tolerance of the hyposensitization treatment was judged excellent. In conclusion, the calcium phosphate absorbed allergen extracts are confirmed as efficient and safe in immunotherapy.

Adolescent↗
PubMed1986

[Desensitization for 4 successive years using calcium phosphate-adsorbed pollen extracts: study of sera with RAST and PRIST immunoimprints].

The clinical study for four years running of desensitization treatment to adsorbed pollen calcium phosphate, prepared "at request" by Institut Pasteur, shows that these preparations produced particularly good results. The population of allergic subjects is divided into two categories as from first year of treatment: good responders and non responders. A study on the serums of these patients, in view of a different "immuno-imprint" in these two groups, has not yet been conclusive, whereas we were expecting much from this prognosis test, which would have given us better treatment information.

Adolescent↗