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K Tóth

Publications and source records attributed to K Tóth.

264 records · Page 15Linked to original sources
PubMedDate not supplied

Role of pesticides in hepatocarcinogenesis.

Pesticides are biologically active substances that are significant environmental contaminants. Only a few of the many pesticides have been subjected to short- or long-term carcinogenicity tests. To date, 16 of them have been identified as hepatocarcinogenic agents in animals, usually mice. However, their cancer-inducing effect in humans has not been completely proved. The use of short-term screening tests (first of all the Salmonella-microsome test) for routine screening of pesticides on a large scale is highly recommended. The herbicide 2,4,5-trichlorophenoxyethanol (TCPE) containing different amounts of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was tested for carcinogenicity in Swiss mice. TCPE enhanced liver tumors in males but TCDD did not affect liver tumor incidence. The occurrence of liver tumors was shown to be dose-dependent. There was no correlation between the results of in vivo carcinogenicity studies and the induction of aryl hydrocarbon hydroxylase and biphenyl 2-hydroxylase activities.

2,4,5-Trichlorophenoxyacetic Acid↗
PubMedDate not supplied

Putative role of dihydropyrimidine dehydrogenase in the toxic side effect of 5-fluorouracil in colorectal cancer patients.

Dihydropyrimidine dehydrogenase (DPD) is the first and rate limiting enzyme in the catabolism of 5-fluorouracil (5-FU). It has been reported from various laboratories that the plasma concentration of 5-FU was influenced by DPD activities in various normal human organs (e.g. liver or lymphocytes). Since the congenital deficiency in DPD caused severe, in some cases lethal, FU-related toxicity, it was decided to collect data about the DPD activity in colorectal cancer patients in order to investigate the possible correlation between the enzyme activity and appearance of the side effects of 5-FU. Assuming that DPD activity in lymphocytes represents the 5-FU catabolic capacity of the organism, DPD activity was determined in the lymphocytes of 48 patients with colorectal cancer after surgery during the therapeutic course with 5-FU and folinic acid. On the basis of the enzyme activity, patients were divided into three categories: low (DPD <5.03 pmol/min/10(6) lymphocytes); medium (DPD = 5.04-13.25 pmol/min/10(6) lymphocytes), and high (DPD > 13.26 pmol/min/10(6) lymphocytes) activity groups. By evaluating the toxic side effects during the 5-FU + folinic acid treatment, the following results were obtained. In the low DPD activity group, 9 of 11 patients had 5-FU-related side effects (mucositis, diarrhea, myelotoxicity, angina pectoris, hypertension). In 3 patients, no change of the therapy was needed, in 3 patients symptoms could be reversed by dose reduction of 5-FU while in 3 patients interruption of 5-FU therapy was needed. In the medium DPD activity group, mild toxicity (diarrhea, transitory hypertension) occurred in 5 of 29 and in the high activity group (diarrhea) in 1 of 8 patients, respectively. In these last two groups, no dose reduction of 5-FU was necessary. The present study furnished further evidence for the possible correlation between the 5-FU side effects and DPD function. Consequently, it is recommended to measure DPD activity prior to 5-FU based chemotherapy, which might be helpful in avoiding drug-related toxicity by adjusting the dose of 5-FU individually.

Adult↗
PubMedDate not supplied

[Experimental 3-month study of safety of textured soybeans Becsei].

The authors conducted a three-month safety test of a textured soy (TS) product manufactured by the Agricultural Plant, Boly. Young male and female rats received semisynthetic diets containing 8, 18 and 38% of TS protein or casein supplemented with methionine, as the only source of protein. The effect of the diet containing 18% of TS protein on the growth, on certain parameters of protein and fat metabolism and on the zinc and copper status corresponded to that produced by 18% of casein supplemented with methionine. When the content of TS protein was lower or higher than the optimal (18%), the development of rats fell behind the control ones receiving adequate amount of casein. High doses of TS protein produced a favourable effect on lipid metabolism in the liver, but its effect on zinc metabolism was unfavourable. No signs of toxic action of the TS product were recorded during the three-month safety test of TS.

Animals↗