Biomedical subjects
Publications and source records attributed to R Truhaut.
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Semi-chronic ecotoxic effects are measured by studying mortality and reproduction of daphnids, grown in toxic medium and fed with toxic chlorellae during 4 weeks. Toxic biosorption is controlled analytically. Toxicity of Cd++ at a concentration of an order of magnitude of by liter is revealed after 14 days. Cr6+ appears non toxic at concentrations under 25 micrograms/l.
The cigarettes studied are smoked through an automatic device. The mainstream smoke is trapped in Citrate-Phosphate buffer pH 4.5 containing 20 mM ascorbic acid. The volatile nitrosamines are extracted in dichloromethane, purified on alumina column, then analysed by gas-chromatography with a thermal energy analyzer (TEA) detector. The two main volatile nitrosamines quantified are: Nitrosodimethylamine and Nitrosopyrrolidine.
The effect of stress from cold and noise on rats fed with DDT in a sufficient dose of retinol is to increase growth and induce cytochrome P450 in the liver, but to a lesser extent than in control group kept in normal environment conditions.
The study of food chain contamination in nature or in the laboratory requires precise definitions of some terms. A simplified model of a freshwater food chain has been elaborated to try to point out hazards related to the presence of cadmium in the aquatic environment. Three different species belonging to various trophic levels, but to the same aquatic systems were used. The required biological and analytical criteria are described. The time course of the experiment was 34 days starting with a 10-day contamination of the first trophic level (algae). The algae were then separated, washed with fresh medium, and given to the second trophic level (daphnids) to eat for 20 days. The third trophic level (fish) was then introduced for 4 days as a scavenger. The methodology was designed to determine the accumulation of cadmium by daphnids and then fish from the algal source. The results show a high direct bioaccumulation of cadmium in algae. The indirect bioaccumulation of daphnids was of the same order of magnitude, but for fish it was smaller. Nevertheless the cadmium transfer from daphnids to fish was obvious.
Sorption of toxics by algae may be important and occurs very early. Thus, a decrease of the experimental toxic concentrations in the medium results in understating toxicity when tests are conducted under static conditions. In this work, two different methods of exposure of algae (Chlorella vulgaris) are studied, the static test and the pseudodynamic test. Acute effects (biological and analytical effects) of inorganic compounds (Cu2+, Cd2+, Pb2+, Cr6+) have been evaluated for 96 hr of exposure; in each case, IC50 is much lower in the dynamic condition than in the static one. The percentage of reduction varies from 55 to 75% after 96 hr. Accumulation of metal by chlorellae is greater when testing by the pseudodynamic way, with Cu2+ and Pb2+. But in the case of Cd2+ and Cr6+, the concentration factors are similar in the two kinds of exposure. These results point out the advantage of the pseudodynamic test, of which the methodology is very easy, for a more realistic assessment of acute ecotoxicity in these organisms.
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The primary cutaneous irritation of 56 chemicals was tested in the rabbit using three different procedures. The three protocols selected for the tests were the method published by the French authorities for the testing of cosmetics and toiletries (Journal Officiel 21 April 1973, p. 3862; ibid 5 June 1973, p. 3953) and the methods proposed for the testing of chemicals by the Association Française de Normalisation (AFNOR) and, in 1979, by the Organisation for Economic Co-operation and Development. The results of the three sets of tests were compared and the effects of differences in procedure and numbers of animals were studied, together with the possible relation between irritancy and the pH of the test material. It was concluded that the AFNOR protocol best met the requirements for such tests and that gloves should be worn for the handling of all substances classified as moderately or severely irritant on that scale.
The ocular irritancy of 56 chemicals was tested in the rabbit eye, with and without rinsing, using a procedure that complied with the main requirements of three protocols, namely those proposed by the Association Française de Normalisation (AFNOR) in 1982 and by the Organisation for Economic Co-operation and Development in 1979 for the testing of chemicals and that published by the French authorities (Journal Officiel 21 April 1971, p. 3862; ibid 5 June 1973, p. 3953) for the testing of cosmetics and toiletries. The results obtained were used to establish the extent to which the assessment of a chemical's irritation potential was affected by the differences between the three protocols in respect of the observation times prescribed, the inclusion and timing of rinsing, the number of animals used and the interpretation procedure. Conclusions were also drawn about the influence of the physical state and pH of a material on its potential irritancy and about the level of irritancy that necessitates the use of eye protection.
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Chemical substances as feed additives, pesticides, drugs or natural toxicants, may enter in the body of farm animals. They are then accumulated, transformed in metabolites more toxic but, generally, less toxic than initial ingested compounds. Farm animals are a biologic active relay able to change entirely conclusions from a direct toxicological evaluation on laboratory animals. It must be also underlined that physical and chemical very sophisticated methods carried out for isolation of toxics are not always in agreement with "in vivo" assays. We must consider residues availability. The methodology called "relay toxicity" consists essentially on the submission of the animal product which contain a mosaic of residues available or not, to long term testing in laboratory animal as pseudo-consumers. So it is possible to measure influences of a lot of metabolite in a dietary context. For these reasons we are thinking it is an appropriate procedure, taking its place among the test to be undertaken for a biological and a more realistic evaluation of additives drugs, pesticides residues or natural toxicants in the feeds of farm reared animals whose meat, eggs or milk will be eaten by human consumers.
During the past years, many publications and reviews have described kidney and bone lesions observed after human chronic cadmium poisonings of food or occupational origin. In this experiment carried out in rat fed with normal diets or polydeprived of vitamin D3, calcium and proteins, with or without addition of cadmium, the bone lesions observed are as severe in all polydeprived animals, wether treated with cadmium or not.
An original approach to reveal in Mice, the impact of some xenobiotics and drugs on the alveolo-capillary barrier...(ethanol, acetazolamide, cyclophosphamide is described. Drugs are injected I.P. during five days in subacute dose size. Concentrations of lecithines and proteins are settled in bronchoalveolar lavage fluids from animals having or not undergone an important blood loss just before the lavage.
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Methyl carbazate, a metabolite of carbadox in the rat, was administered orally to rats for 2 years. The compound was mixed in the diet at concentrations corresponding to dose levels of 0, 2.5, 5 and 10 mg/kg body wt/day. There was no evidence of any treatment-related toxicity or, in particular, of carcinogenicity.
Relative to an industrial application, the authors relate results obtained from a peculiar study on the thermic degradation of bis (tri-n-butyltin) oxide (TBTO) at various temperatures and they account for the toxic effects observed after inhaling the combustion products in the mouse and guinea pig. Thermolysis of TBTO between 200 and 600 degrees C gives saturated hydrocarbon and olefin gas, a condensate of tetrabutyltin and dibutyltin oxide and a residue composed of stannous or stannic oxides according to the temperature. Pulmonary toxicity is very important at low temperatures but after heating, toxic effects decrease. The results are confirmed by localisation and histopathologic studies. At 600 degrees C no death appears but some behavioral troubles occur. It's possible that repeated exposures can induce delayed toxicity.