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Biomedical subjects

R Truhaut

Publications and source records attributed to R Truhaut.

At least 91 records · Page 5Linked to original sources
PubMed1976

[Inhibitory effect of ellipticine (dimethyl-5,11-(6H) pyrido (4,3-b) carbazole on the induction of liver cancer by BT6 (N,N-dimethyl-p-(benzothiazolylazo) analine) and its effect on the levels of cytochrome P450 and arginase activity].

Under the conditions of our tests, ellipticine inhibits remarkably the carcinogenic action of BT6 on the liver, characterized, in particular, by the swiftness of its outbreak. Under the influence of this carcinostatic compound, a considerable activation of liver metabolism is observed, resulting in an hyperproduction of cytochrome P450, while the arginase capital is restored after an appreciable fall, as if ellipticine played a favourable part in the safeguard of this enzyme, recognized as one of the targets of liver carcinogens. The relationships between various effects of ellipticine are discussed.

Alkaloids↗
PubMed1976

[Results of 8 years' research on the toxicologic evaluation of animal food additives by the so-called relay toxicity method].

The authors report the underlying principles of the new methodological approach called "relay toxicity" which they proposed eight years ago for the toxicological evaluation of animal feed additives. They stress its value either as a possible criterion of rejection or as a criterion of acceptability. In the latter case, the limiting factor is the difficulty of applying an adequate safety factor when food products destined for human consumption and obtained from animals receiving the additives to be evaluated are administered to laboratory animals. Amongst the examples of the additives which have been subjected to toxicological evaluation using the authors' new method, the following are examined: as growth factor, carbadox, anabolising agents and, in particular, diethylstilboestrol, and steroids used as egglaying potentializers. The results obtained are discussed.

Anabolic Agents↗
PubMed1976

[Risks of mercury poisoning in the dental laboratory].

We present the results of an inquiry about the hydrargyric risk run by the staff of an odonto-stomatological laboratory. A second laboratory in which mercury was not used, served as a control. It would appear that the staff in the laboratory where the practician uses amalgam have a level of mercury higher than that of the staff working in the control laboratory. This level reaches the maximum in the middle of the day and returns to the same level as that of the controls after the nights rest outside the polluted atmosphere. These results are discussed in the light of our findings and of facts obtained from literature.

Adult↗
PubMed1976

[Specific toxicological considerations on anabolic agents; transmitted toxicity].

The growth of populations and the spread of urbanization, resulting in new agricultural structures, have entailed a concentration of livestock production and recourse to new techniques. Of some importance among these techniques is the enteric or parenteral administration of substances in very low doses. These substances include anabolic agents, some of which, like many natural feeds, exhibit hormonal activity. They may be divided into two classes: --those of the DES type, synthetic compounds non-existent in the natural state, --natural agents, which are normally distributed throughout the animal and human organism, and hence in food of animal origin---milk, meat, eggs. The compounds belonging to the second class may also be synthesized and the main toxicological consideration is that they then have to meet clear-cut standards of identity and purity. A compound belonging to the first class, diethylstilbestrol (DES), administered to rats in doses as small as 60 mug/kg of feed or even smaller, causes in general lower growth rates as well as alterations in the genital system and reproductive functions. In long-term experiments (12 months) using rats and mice and applying so-called toxicity "de relais" tests, developed and described by the authors, it also appeared that meat from calves in which DES pellets were implanted under normal rearing conditions, inhibits growth and reproduction in mice and rats fed a diet containing 20% of this meat. Studies in which the livers from treated calves constituted 6% of the diet of these two rodent species also led to the conclusion that fertility was impaired in the second reproduction test. The authors also recall cases of vaginal cancer observed in young girls whose mothers had been treated with DES during pregnancy. Compounds belonging to the second class (estradiol-progesterone and estradiol-testosterone) gave no evidence of harmful effects upon rats when mixed with their rations during short and medium-term trials. Similar results were obtained from studies with rats and mice fed a diet containing 20% veal or 6% liver of calves in which pellets of these natural hormones had been implanted. In these studies, which lasted 23--24 months with rats and 347 days with mice, the toxicity "de relais" test was applied under similar conditions to those undertaken using meat and livers of implanted calves. The report also refers to trenbolone and to "zéralénone" but no toxicity "de relais" tests were carried out with the meat and livers of animals treated with these substances. The authors reached the following conclusions: DES should not be used as an anabolic agent in livestock production. Natural hormones prepared through synthesis or otherwise could be used as anabolic agents in livestock production since no risk to the consumer has been witnessed when they were administered at doses similar to those used in the author's experiments. However, it is recommended that they should be applied under veterinary supervision...

Anabolic Agents↗
PubMed1976

Use of the golden hamster in toxicology.

The choice of an appropriate species and strain of laboratory animal is one of the toxicologist's major concerns. The biochemical, anatomical, and other characteristics of the golden hamster which make it a valuable though limited tool in toxicologic research were reviewed. The effects of organochloride insecticides on rats, mice, and hamsters were compared. These substances can be classified into 3 groups based on the hamster's sensitivity to acute toxic effects. The hamster is so insensitive to DDT and its immediate metabolites, DDD and DDE, that an LD50 cannot be established, whereas the hamster's sensitivity to other organochlorides varies when compared with mouse and rat sensitivity. The long-term effects of sub-lethal doses of organochloride insecticides on biochemical pathways were evaluated, particularly on liver function. The details of the induction of drug-metabolizing enzymes in the hamster and in the rat were also explored.

Animals↗
PubMed1976

[Analysis of volatile N-nitrosamines. A brief review].

The different steps of analysis of volatile N-Nitrosamines: separation from product, clean up, detection, quantification and confirmation are reviewed and discussed. The two best analysis procedures are: 1) combined gas-chromatography; mass-spectrometry, 2) combined gas-chromatography; thermal energy analyzer. However a bundle of proofs is always necessary to ascertain the presence of Nitrosamines.

Chemical Phenomena↗
PubMed1975

[Alpha-mannosidase activity of different human biological fluids].

Two distinct alpha-mannosidases have been found in biological fluids by investigating the effect of pH on activity, the effect of Co2+ and Zn2+ and by determining the Michaelis constant. The two enzymes are designated as S, predominating in serum (optimum pH about 5.6) and U, predominating in urine (optimum pH about 4.2). In cerebro-spinal fluid, the amount of alpha-mannosidase S is almost the same as that of alpha-mannosidase U. Alpha-mannosidase S activity in sera is significantly higher in children than in adults.

Adult↗
PubMed1975

[Preparation of an iodinated penicillin derivative for radioimmunologic use].

A 125I-BSA Penicilloyl conjugate was prepared by coupling Penicillin G to Bovine Serum Albumine previously labeled with Iodine-125. The reaction of fixation by covalent binding was made in alkaline solution without the use of carbodiimide. Immunoreactivity and specific activity of this labeled conjugate enable radioimmunoassay of penicilloyl groups.

Chemical Phenomena↗
PubMed1975

[Cytotoxicity of aurintricarboxylic acid: inhibition of cell proliferation and of protein synthesis in Allium sativum L. root meristems].

The inhibitory action of aurine-tricarboxylic acid (ATA) on protein synthesis, known in vitro, has been checked in vivo in Allium sativum L. root meristems. Parallel to this inhibition, ATA acts on cell proliferation, on the one hand by preventing the entering of cells into prophase and, on the other hand, by disturbing the process of mitosis.

Aurintricarboxylic Acid↗
PubMed1975

[Toxicity by relay. I. General principles of a new method for the assessment of Toxicity of addivitives to animal feeds].

Chemical substances added for various purposes to the feeds of farm-reared animals may enter the body of these animals. This may lead to the persistence, in food offered for human consumption, of residues which may be potentially toxic under conditions of repeated absorption over the greater part of the life span. The evaluation of the safety of these residues for man poses complex problems. Their ideal solution demands very often a number of careful experiments. The methodology called "toxicity by relay" consists essentially of the submission of the animal feed itself, which is likely to contain a mosaic of residues, to long-term testing in laboratory animals. Provided a satisfactory safety factor can be applied, this methodology can contribute information permittinga conclusion regarding the acceptablity, even provisionally, of the feed additive for the use which is envisaged. In addition this methodology enables the provision of results constituting a criterion for the rejection of the additive under test. For these reasons it appears to us an appropriate procedure, taking its place among the tests to be undertaken for the toxicological evaluation of additves to the feeds of farm-reared animals.

Animal Feed↗
PubMed1975

[Toxicity by relay. II. A method for the asessment of safety to human consumers of carbadox, a growth-promoting additive to the feed of slaughter pigs].

A toxicity by relay. II. A method for the assessment of safety to human consumers of carbadox, a growth-promoting additive to the feed of slaughter pigs. A new methodology called "toxicity by relay" has been used to assess the potential hazard to humans of incorporating an additive into animal feeds. This methodology considers a farm-reared animal as a "relay" between the food additive and the human consumer, and employs laboratory animals as "pseudo-consumers". These laboratory animals are fed throughout their entire lives with the meat or organs of the "relay" animals which have been reared on feeds supplemented with various levels of the additive. In the present study, the toxicity of carbadox was assessed in this way. In pigs, where it is used as a growth promoter, carbadox is metabolised into serveal different products, and so an assessment of its safety using traditional methods of studying the toxicity of a substance and tis known metabolites, would perhaps be subject to error. A safety factor for man, in relation to the safety factors for rats and dogs, was calculated using (a) the comparative consumption of the laboratory animals and man; (b) an assessment of the highest dosage likely to be consumed in normal circumstances compared to the laboratory dosage, and (c) the consideration that in the laboratory there is no period of withdrawal from feeding before sacrifice as is the case with animals for slaughter. Pigs were used as "relays" in the present study by supplementing their feed with carbadox. The meat and/or livers of these animals were then fed daily to (a) rats for a period of 3 generations; (b) rats for 24-25 months, and (c) dogs for 60 months. No abnormalities were observed at the termination of the experiments. We may therefore conclude that there is no hazard for the human consumer from the use of carbadox as a pig-feed additive.

Animal Feed↗
PubMed1975

[Azo dyes and vitamin A reserves in the liver].

Amaranth and Sunset Yellow FCF, added to the basic diet at 1200, 3000, 10 000 and 20 000 mg/kg, influence, after 10 days' administration to rats, neither the percentage of vitamin A stored in the liver in relation to the quantity of vitamin taken, nor the hepatic reserve expressed in IU/g of liver.

Amaranth Dye↗