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Biomedical subjects

C Cavelier

Publications and source records attributed to C Cavelier.

49 records · Page 3Linked to original sources

Surface chemistry and cytotoxic properties of silica.

Aluminium inhibits the harmful effect of quartz on the lungs. Current interest in such protective phenomena has lead us to consider a possible method of bonding aluminium to the crystal lattice, and to see if other atoms might have the same effect. A study of the structure of natural and artificial alumino-silicic compounds shows a surface state specific to quartz, namely the existence of vacancies in the three-dimensional SiO4 tetrahedral structure. Aluminium is a known inhibitor of the cytotoxic action of quartz, and can replace the missing silicon atoms in the crystal lattice. The result is the generation of finite numbers of heat-resistant acid sites. Thus it is not a question of a simple zeolite surface layer, but of the substitution of aluminium atoms for silicon atoms in the remaining crystal lattice. It can be shown that other atoms, such as sulphur and specially phosphorus, are capable of behaving in the same way as aluminium. There is reason to believe that the cytotoxic properties of quartz may be related to the crystal capturing atoms from the cell membrane. The large number of thermally stable acid sites detected after contact with alumina would then be a factor for assessing the cytotoxic properties of the various forms of quartz.

Aluminum↗

[Toxic dermatitis and pseudo-contact allergy].

A contact dermatitis is more often due to skin irritation than to allergic reactions. About 80% of occupational dermatoses are explicable as toxic reactions of the skin, 20% as allergic reactions. Frequency and severity of the diseases depends on the nature and concentration of a substance as well as from the duration of its action on the skin. Defense mechanisms against chemicals are influenced by sebum content, humidity and the integrity of the horny layer. From a practical standpoint it is important to differentiate toxic from allergic reactions in a patch-test. It seems that allergic reactions are diagnosed too often. The determination of the critical non-toxic concentration requires the evaluation of a sufficient number of patients. The differentiation of irritation and allergy is tendered more difficult by individual factors. The therapy of toxic and allergic contact dermatitis is discussed.

Allergens↗

Occupational eczema from N-isopropyl -N'-phenylparaphenylenediamine (IPPD) and N-dimethy-1,3 butyl-N'-phenylparaphenylenediamine (DMPPD) in tyres.

Forty-two cases of contact sensitivity to N-isopropyl-N'-phenylparaphenylenediamine (IPPD), an amine antiozonant used in rubber manufacture, were collated from several firms and plants dealing with tyres. Ten motor car tyres manufactured by eight different firms all induce sensitivity reactions in seven subjects allergic to IPPD. Clinical cross-reaction tests show that 100% of the subjects sensitive to IPPD are also sensitive to N-phenyl-N'-cyclohexy-paraphenylenediamine (CPPD), another amine antiozonant, and 37% to paraphenylenediamine (PPD). The various types of tyres were analyzed by gas chromatography and then by infra-red and thin-layer chromatography where necessary. None of the 12 tyres examined was found to be free from aromatic amines. Test reactions carried out with various automobile accessories on subjects allergic to IPPD in tyres gave positive results precisely in those cases where the articles contained IPPD. The authors then studied occupational sensitivity to N-dimethyl-1,3 butyl-N'-phenylparaphenylenediamine (DMPPD), a rubber antiozonant purported to be non-sensitizing and marketed in the United States. The The DMPPD tests were positive for all the IPPD-allergic patients tested; there is no doubt as to the allergenic nature of DMPPD. The irritant and sensitizing potentials of the four amines in question were tested in laboratory animals: PPD proved to be the most allergenic product, IPPD the least allergenic, and DMPPD and CPPD seem to give identical results. All these products produce positive cross-reactions in varying degrees of severity.

Animals↗

Allergic contact dermatitis to a photopolymerizable resin used in printing.

Organic photopolymerizable resins increasingly used in printing make it possible to produce flexible, lighter plates. A certain number of skin lesions and general symptoms appeared upon manipulation of plates made by the Letterflex process. In the workshop where this study was carried out, 12 out of 15 people suffered various degrees of skin lesions. The epicutaneous tests and biopsies performed indicate an allergic type reaction to one of the resin's constituents, polythiol. Experiments with animals confirm the strong allergenicity of this compound.

3-Mercaptopropionic Acid↗

[Has N-isopropyl-N'-phenylparaphenylenediamine a place among standard allergens? Importance of this allergen in rubber intolerance].

Allergic contact dermatitis to N-isopropyl-N'-phenylparaphenylenediamine (IPPD) from rubber is far from being exceptional. Out of a total of 56 cases of allergic contact dermatitis to IPPD, 42 were considered as caused by occupational contacts: 17 cases were found in tyre manufacturers, 9 in car-mechanics, 9 in drivers, and 7 in various industrial branches. Out of the 56 cases, 23 also reacted allergically to mercaptobenzothiazole or to tetramethylthiuramdisulphide, or to both of these substances. In a chromatographic analysis of samples of 9 different tyre brands, IPPD was found in 8 cases.

Allergens↗

[Allergic eczema due to textile pigment-supports].

A worker employed in a textile printing-shop showing a rebellious eczema on hands and forearms, was submitted to three series of patch-tests which disclosed a polysensitization to chromium, to formaldehyde, to the urea-formaldehyde resin and to some pigments (Helizarine BASF, Fluolac FMC). The chemical analysis of some of these pigments shows an interesting relation between allergenicity for a certain pigment and the presence of formaldehyde. Thus, it is an allergy to the pigment-support and not to the pigment itself.

Coloring Agents↗

Irritant dermatitis from diallylglycol carbonate monomer in the optical industry: clinical and experimental studies of cutaneous tolerance and chemical investigations.

The diallylglycol carbonate monomer causes dermatitis due to irritation in the optical industry. Cutaneous intolerance may effect as many as 70% of the exposed persons employed. Almost all control subjects who where patch-tested showed irritation at a 2% concentration. The histological effects were an acute oedema with inflammation of the papillary dermis, and diapedesis of neutrophil polymorphonuclear leukocytes. Experiments on animals confirmed the irritant nature of the product; in the rabbit, a single application produced irritation, but to a lesser degree than in humans. Tests for possible sensitizing effects in the guinea pig have given negative results. Chemical analysis of the monomer revealed the presence of diallyl carbonate and acrolein. Allyl alcohol was detected in only one case. Patch tests were carried out in a group of control subjects with acrolein, diallyl carbonate and allyl alcohol. The histological appearance of the lesions caused by acrolein was quite different from that due to diallyglycol carbonate. It is probable that the irritant is the diallylglycol carbonate monomer itself.

Animals↗

Occupational eczema from para-tertiary-butylphenol formaldehyde resins: a review of the sensitizing resins.

The first case of allergy due to para-tertiary-butylphenol formaldehyde resins (PTBP resins) were found in 1958 in the shoe-making industry. These resins are found in certain neoprene adhesives. PTBP resin hypersensitivity may be due either to the para-tertiary-butylphenol, to the resin itself or less frequently to the formaldehyde. These resins may cause occupational allergy (in the automobile industry and chiefly in the shoe-making industry) and non-occupational allergy (footwear and clothing hypersensitivity). Patients allergic to PTBP resins have been found to show a cross-reaction to other resins such as Alresen PA 103, Schenectady SP 126 and Schenectady SP 154. The authors give a reference list of sensitizing neoprene adhesives and PTBP resins so that manufacturers can limit the use of these products as far as possible.

Dermatitis, Occupational↗

[Consumption and nutritional contribution of the blue algae (Oscillatoria platensis) among some populations of Kanem (Tchad)].

Two food surveys determined the areas of consumption and the ethnic groups involved as well as the way and motivations for using Spirulina algae (Oscillatoria platensis) in Chad. More than 400 homes were visited in February (dry season) and October (end of the rainy season and period after the millet harvest). Consumption is limited to a restricted proportion of the population in the Kanem region. Among the Kanembu group (the leading consumers of Spirulina), frequencies of use vary between one and six melas out of ten. The amounts consumed per person during a meal, in the sauce accompanying millet, are between 9 and 13 g. Variations in consumption linked to ethnic, social and seasonal factors are discussed. With regard to food value, the very high proportion of sand considerably reduces the protein content in the product sold on the market. An average ration of sauce containing "diĕ" helps cover about 10 to 12 p. 100 of the protein requirements of an active adult man, and the algae by themselves contribute 5 to 8 p. 100 of these requirements. A comparison with the leading sauces consumed in Kanem reveals no superiority for Spirulina.

Adult↗

[Pulmonary function indices: variability, predicted values and discriminating power (author's transl)].

Flow/volume curves, single-breath N2 washout curves, single-breath and steady-state carbon monoxide diffusion tests were performed on 229 firemen (aged 20 to 55 years) and repeated one week later on 183 of them. According to a questionnaire, 58 were asymptomatic non-smokers, 130 were asymptomatic smokers and 34 were smokers with symptoms of cough with or without sputum. Intra-individual variability of indices determined from tests performed at a week interval is not always aleatory and it is different in the three groups. It is the same for inter-individual variability which is lowest in asymptomatic smokers and highest in symptomatic smokers. Age and height were the most important factors in inter-individual variability for spirometric indices but do not affect the variability of the slope of N2 curve (delta N2) or fractional uptakes of CO. The ratio of residual variance (adjusted for age and morphometric parameters) on intra-individual variance indicated the choice of "sensitive" functional indices. This choice may be reached in a different way by comparison of means of groups distinguished according to symptoms or smoking habits. Reference equations for indices derived from each test are proposed. The problem of the choice of "sensitive" indices and the problem of reference groups and reference values are discussed.

Adult↗