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G Ducombs

Publications and source records attributed to G Ducombs.

At least 55 records · Page 3Linked to original sources
PubMed1985

[Thaumetopoein, an urticating protein of the processionary hairs of the caterpillar (Thaumetopoea pityocampa Schiff) (Lepidoptera, Thaumetopoeidae)].

The irritating fraction extracted from processionary caterpillar hairs contains soluble proteins which were separated by various electrophoretic and immuno-electrophoretic techniques. Some of these proteins are present also in cuticle and haemolymph. One protein of 28,000 daltons, formed of two subunits (13,000 and 15,000 daltons) is hair specific and causes a reaction in pig skin identical to that produced by hair extract. It is therefore an urticating protein and which we have named "Thaumetopoein".

Animals↗
PubMed1983

Irritating substance extracted from the Thaumetopoea pityocampa caterpillar; mechanism of action.

Hairs of the Thaumetopoea pityocampa caterpillar (Lepidoptera) cause cutaneous reactions in men and animals. A soluble substance extracted from the hairs has been shown to cause a reaction in guinea-pig skin, probably caused by mediators released by mast cells. A direct effect of this substance on mast cells has been shown. Degranulation of mast cells was found to be dose-dependent. Heating of this substance greatly reduced its effects. Proteins fractions are currently being extracted and will be submitted to the same tests.

Animals↗
PubMed1983

[French Guiana "papillonite" (lepidopterism). Clinical and epidemiological study].

Clinical studies by Dr R. Pradinaud (Cayenne) has given prominence to the symptoms of "papillonite": its primary and secondary cutaneous lesions, their localisation and evolution as well as its accompanying symptoms such as respiratory pathology. Epidemiologic survey shows a parallelism between the occurrence of papillonite and the presence of the moth Hylesia urticans. The urticant apparatus of this moth was studied with the scanning electron microscope. "Arrow" (fléchettes) were found and they more or less resemble the urticant apparatus of Thaumetopoea pityocampa Schiff caterpillar. The mechanism of action has been studied in the animal and in humans. Extracts prepared from the "arrows" have been rested in vivo guinea-pigs (bleu Evans, Liacopoulos et al.). The findings seem to incriminate an histamino-liberation.

Animals↗
PubMed1982

[Allergy to preservatives].

This study concerns 465 patients with dermatitis. The clinical history suggested allergy to cosmetics, drugs, industrial products or clothes. These patients were tested with 29 preservatives chosen among the most frequently employed or most sensitising products. Seven french clinics of Dermatology were involved in this study during one year. The patients' age varied between 2 years old and 80 years old. Positive reactions were seen mostly with formaldehyde (4.7 p. 100), Bronopol (4.7 p. 100), ammoniated mercury chloride (3.8 p. 100), benzoic acid (2.1 p. 100), sodium benzoate (1.9 p. 100), parabens (1.9 p. 100), dichlorophen (1.7 p. 100), chloracetamid (1.5 p. 100), benzyl benzoate (1.5 p. 100), Germall 115 (1.2 p. 100), butylhydroxyanisol (1 p. 100) and Dowicil (0.8 p. 100). The incidence of sensitivity to formaldehyde, Bronopol, ammoniated mercury chloride is too high; their use should decrease. Patients sensitive to benzoic acid, benzyl benzoate are not rare. Chloracetamid whose frequency of uses seems to be rather low is a very sensitising product. Parabens which are widely used were seldom found positive; nearly all cases are caused by topical medications.

Adolescent↗
PubMed1980

Eau de Javel and prevention of chromate allergy in France.

"Eau de Javel" (liquid bleach) is a common cause of chromate contact allergy. A historical review explains the reasons for the addition of sodium dichromate after the First World War. The chromium content in different brands of eau de Javel has been determined by flameless atomic absorption spectrophotometry. The results indicate that the chromium content is very low (0.03--3.65 mg/l) in French brands, whereas it is still important (7.06--82.9 mg/l) in Belgian brands, such an observation indicates that the almost complete removal of chromate in most brands of French eaux de Javel is a good example of prevention in the field of contact dermato-alllergology.

Belgium↗
PubMed1979

[Thaumetopoea pityocampa caterpillar and man. Morphology of its venom apparatus. Epidemiological investigation (author's transl)].

The combination of a mechanical phenomenon (penetration of the hair) and a chemical phenomenon (discharge of a toxic substance) accounts for the pathological symptomatalogy induced by the processional pine caterpillar. Epidemiological study has pin-pointed the regions infested by the pine caterpillar and has described in detail the dermatitis inflicted by this caterpillar with special emphasis on the frequency of ocular lesions. Also, a close correlation was noted between the geographical density of the populations of Thaumetopoea pityocampa Schiff and the geographical density of the clinical cases recorded. Skin tests have confirmed that the urticant substance is histamino-liberating. A morphological study of the urticant apparatus of this caterpillar ("mirror" and urticant hairs) was undertaken with the scanning electron microscope. The progressive coming into place of the bristles on the cuticular pads of the "mirror" was followed during the last three larval stages (L3, L4 et L5). The urticant hair, hollow on the inside, carries pointed spikes directed towards its distal end. There is no hole or pores on the hair and the necessity to grind the bristles in order to extract the urticant substance leads us to believe that the hair is really a bulb which must be broken, for example in the skin, in order to release its urticant substance (histamino-liberating).

Adolescent↗
PubMed1978

Allergic contact dermatitis due to sesquiterpene lactones. A comparative study of human and animal sensitivity to alpha-methylene-gamma-butyrolactone and derivatives.

Several compounds containing the alpha-methylene-gamma-butyrolactone moiety have been tested on human volunteers and on guinea-pigs; the animals were experimentally sensitized by alantolactone, isoalantolactone and laurel oil. Of the two new lactones, spirolactone was the more reactive: this was confirmed by both animal and human testing. The synthetic lactones are less reactive than natural ones. alpha-Methylene-gamma-butyrolactone itself does not elicit cross-reactions in guinea pigs sensitive either to alantolactone or to isoalantolactone, or in patients sensitive to sesquiterpene lactones. The alpha-methylene-gamma-butyrolactone group is necessary for cross-reaction, but to be active, it has first to be substituted. It was also found that isoalantolactone, allegedly not allergenic, is in fact a sensitizer and cross-reacts with alantolactone. The cross-reaction between laurel and Frullania, found in man, also occurs in guinea-pigs. It is more evident when sesquiterpene lactone is the sensitizer and laurel used to elicit reaction.

4-Butyrolactone↗
PubMed1978

Concentrations of patch test allergens: are we comparing the same things?

A new way of expressing the concentrations of patch test allergens solutions (or emulsions) is proposed. From these new expressions it can be seen that apparently similar concentrations (0.5% chromium, 2% formaldehyde) can actually be in the ratio 1 to 15 as expressed at the molecular level.

Allergens↗