Biomedical subjects
Publications and source records attributed to J Farkas.
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The effects of allopurinol on the plasma clearance and metabolism of theophylline in man were investigated under single-dose and multiple-dosing conditions. No change in theophylline clearance was found with the concomitant use of allopurinol but 1-methylxanthine (1MX), a theophylline metabolite not previously described in man, was detected in urine during control and allopurinol treatment phases under both single- and multiple-dosing conditions. 1MX excretion increased at the expense of 1-methyluric acid (1MU) during the allopurinol treatment phase. It is proposed that the secondary biotransformation of 1MX to 1MU is mediated by xanthine oxidase.
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The hemoglobin level of blood plasma is a sensitive tool in measuring radiation effects. Its value has increased in most of the cases during radiotherapy of cancer patients even applied at low doses. Haptoglobins behave similarly, the time-dependent changes during radiotherapy are almost identical at both parameters.
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The NaCl tolerance of different strains of Clostridium botulinum varies over a wide range, and the patterns of NaCl inhibition differ distinctly and characteristically from strain to strain. The more radiation-resistant strains, such as 33A, 62A, and 7272A, are more resistant to NaCl, whereas the more radiation-sensitive strains, such as 51B and 1304E, are more sensitive to NaCl. This rule appears to hold irrespective of whether the spores were unirradiated controls or whether they were radiation damaged prior to exposure to NaCl in the recovery media. The data seem to indicate that radiation doses in the shoulder portion of the radiation survival curves did not noticeably sensitive the spores to NaCl, whereas radiation doses in the exponential-decline portion of the survival curve invariably produced a distinct sensitization. Thus, strains 33A and 62A were not sensitized to NaCl by 0.3 to 0.4 Mrad, i.e., in the shoulder portion of the survival curve. Radiation-sensitive strain 51B, which shows no distinct shoulder in its survival curve, was sensitized to NaCl by 0.1 Mrad, the lowest radiation dose employed in this study. These observations seem to suggest a possible relationship between deoxyribonucleic acid repair capacity and salt tolerance.
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The antitumoral activity of three amino acid derivatives, S-carbamoyl-L-cysteine, S-ethyl-carbamoyl-L-cysteine, and S-chloroethyl-carbamoyl-L-cysteine, was studied. The ethyl and chloroethyl derivatives had a pronounced curative effect on certain animal tumors. It is interesting in the case of S-carbamoyl-L-cysteine that N-ethylization of the substance resulted in increased chemotherapeutic effectivity with no simultaneous change of the toxicity. According to various studies this effect is different in many respects from that of the known cytostatics, and a possibility of a specific selective or surface activity is raised.
The cause of perioral dermatitis remains unclear. It is not due to the application of fluorinated corticosteroids. For therapy Locoid cream and tetracycline are recommended. There are some cases which are not influenced by any therapy. In these cases psychotherapy is sometimes effective.
Cytostatic effects and some pharmacological properties of a new metabolic inhibitor "3-oxauracil" were studied. The cancerostatic effect was examined on 7 experimental tumors in mice and on two types of tumors in rats. After the i. p. application of 20 mg/kg, there was both a statistically significant decrease of tumor weight and increase of animals' survival time in NK lymphoma of mice. Significant changes in one of both parameters followed occured in all experimental tumors after the i. p. application but only in the Krebs ascitic carcinoma after the oral application of "3-oxauracil". The acute toxicity of the substance in water was 322 mg/kg i. p. and 850 mg/kg p. o. The ethanol solutions were more toxic. The distribution of the 3H- and 14C-labeled substance was followed up in blood, urine, liver, brain and kidney. After the p. o. application, the radioactivity peak was reached after 2 hr in blood and high radioactivity levels were found in kidney followed by brain and liver. 96 hr after the drug was applicated perorally, only 60% of radioactivity was found in urine.
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Derivatives of such related substances as cytosine, uracil, thymine, 6-methyl-uracil, 5-ethyluracil, 5-propyluracil, 5-isopropyluracil, 5-cyclopropyluracil, 5-allyluracil, 5,6-trimethyleneuracil, 6-cyclopropyluracil, 5-cyclobutyluracil and 5-tert-butyluracil have been separated on a column of Spheron P-300. Retention on the column was found to depend on the size of the non-polar part of the molecule. The chromatographic behaviour is analyzed according to the theory of solvophobic chromatography.
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