Toxicological European research. Recherche europeenne en toxicologie最新文献

The ratio methylmercury/total mercury in most of the fishes from Senegalese and Mauritanian coasts in about 50%. It reaches the 100% value for only two species: the "Barracuda" dreadful predator, and the "Merou bronze", known as "thioff" and particularly prized in Senegal; for these fish, we have only analysed big specimens, from 8 to 10 kg.

The authors have studied in the lungs and blood the time course evolution of nitrogen oxides (NO and NO2) administered by inhalation, in rabbits and guinea pigs. NO2 was rapidly oxidized into NO3-. The latter were eliminated within 24 h, the oxidation rate having been variable according to animal species. In presence of NO, the persistence of NO3- beyond 24 h indicates a retardation of the oxidation, NO having to pass previously by the NO2- step.

Chemical and immunological basis of hypersensitivity reactions to low molecular weight substances are recalled. Then the authors give examples of directly reactive chemicals as penicillins and some antineoplastic drugs. The possible role of reactive impurities as penicillins and aspirin is also reminded. It is emphazised that some substances induce allergic reactions through their metabolites: such reactions are mostly unforeseeable. The second part of the paper recalls the main clinical manifestations of these allergic hypersensitivity reactions to chemical residues in food. It is finally emphazised that the datas from animal experiments and epidemiological studies could allow a classification of chemical substances according to their potential risk. This would be of great importance to determine which substances may be authorized in food stuffs and/or to specify the maximum allowable concentrations.

Having defined cytotoxicity and shown the diversity and the advantage of a cellular material, the authors strived to ascertain the chemical affinities of mercury and cadmium, trying to find their toxic potentialities at the cellular level. A global evaluation of the toxicity of these compounds on the different cellular materials was considered. There are several reviews on the principal mechanisms of toxic action, that apply to the most vulnerable targets of the cell, such as the nucleus and nucleic acids, and to a minor degree, the plasmic membrane and the lysosome. The authors conclude, stressing the advantage of punctual cytotoxicity tests, without forgetting the problems that inevitably follow from them. These tests used jointly with other short tests, in vivo, can serve as a first experimental approach to the evaluation of the cytotoxicity of a substance.

The cutaneous penetration of certain number of oxidation dyestuffs for hair [p-aminophenol, 2,4-diaminoanisole, 2,4-diaminophenoxyethanol, resorcinol, 3-acetylamino-2,6-dimethylphenol and the indamine: N-(4'-hydroxyphenyl)-3-amino-6-methylbenzoquinoneimine], either alone or when formulated with other dyestuffs, and under various experimental conditions, has been evaluated in the hairless rat using C14 labeled molecules. It has been found that: Dyestuffs having indamine structures, formed by oxidation of their precursors (bases, couplers), for all practical purposes do not cross the cutaneous barrier. No fixation of those dyestuffs investigated (resorcinol, 2,4-diaminoanisole, 2,4-diaminophenoxyethanol) which do pass through the cutaneous barrier is found in either liver or thyroid of the experimental animals, 4 days after their topical application. The amount of the hairdye 3-acetylamino-2,6-dimethylphenol which penetrates the cutaneous barrier is constant for quantities of hairdye solution greater than or equal to 20 mg/cm2 of skin. The type and composition of the excipient used in the formulation of hairdyes plays an important role in their penetration.

Nitrosamins present in the aquatic medium are considered as carcinogenic substances to the laboratory animals. This experimentation has for object to precise toxicity effects of the nitroso-compounds: nitrosodimethyllamine (NDMA) on two phytoplankton cultures, and on the common mussels. The addition of NDMA to the seawater of aquarium, in particular experimental conditions induces toxicity effects on the growth and behavior of phytoplanktonic cultures and of the common mussels: Mytilus edulis (tissus modification, and attack of some organs).

The solubility in biological liquids of particles which penetrate as far as alveolar compartment, has a determinant influence on their absorption into the blood stream. The experiments conducted in vitro have enabled cadmium oxide dissolution parameters in human plasma at 37 degrees C to be calculated, as well as cadmium dissolved concentration according to time and cadmium particle level, initial dissolution rate and dissolved cadmium concentration at saturation. The smaller the particles, the quicker they dissolve. Dissolved cadmium is distributed between diffusible cadmium (2%) and cadmium binding proteins (98%) chiefly in albumin and IgA. The cadmium binding protein fraction can be mobilized by chelating agents. In vitro studies allow the determination of mobilized cadmium fraction according to time. The calco sodic salt of ethylen diaminotetraacetic acid and N-acetyl-DL penicillamine are the most energetic compounds, compared to meso 2,3 dimercaptosuccinic acid, and 2,3 dimercapto-1-propan sulfonic acid.

Between 1976 and 1980, 35 cases of nadoxolol poisoning were collected from french antipoison centers. Acute intoxication was voluntary (50%) or accidental (50%). The ingested dose ranged between 0,25 and 22,5 g. Clinical symptoms appeared three hours after ingestion and consisted of cardio-vascular disorders which were present in 10 patients: bradycardia (7 cases), cardiogenic shock (6 cases), intraventricular block (5 cases), increase of P.R. interval (4 cases) and Q.T. interval (3 cases). The toxic dose in otherwise healthy adults was 5 g. The treatment consisted of gastric lavage and correction of cardiovascular disorders with sodium lactate (4 cases) or dopamine (1 case). All the patients recovered.

Results of a study concerning the trigeminal nerve impairment as the one caused by trichlorethylene chronic intoxication by somatosensory evoked potential reveal three kinds of anomalies: increase of the stimulation voltage, excessive latency delay with morphological anomalies and excessive graph amplitude. These anomalies confirm clinical disturbance (hypoesthesia in the trigeminal area) and open a debate about the real mechanism of the trichlorethylene neurotoxicity.