Biomedical subjects

J Krawczyk

Publications and source records attributed to J Krawczyk.

24 records · Page 2Linked to original sources

PubMed1990

[Specificity of cytochrome P-450 forms in the rat liver after inhalation of multicomponent hydrocarbon mixture].

Rats were inhaled with C6-C9 petroleum fraction 12 hrs daily for 9 days. The hydrocarbons and their metabolites gas chromatographic profiles from liver, kidney, brain and blood were investigated by means of head space technique. The observed characteristic profile composed of some hydrocarbons and secondary alcohols does not undergo qualitative changes and internal quantitative proportions remain constant in spite of cytochrome P-450 induction. Only total amount of hydrocarbons and their metabolites was varied. The results suggest that C6-C9 petroleum fraction inhalation does not induce new forms of cytochrome P-450 with different catalytic properties, but at the same time substrate binding site is modified to facilitate biotransformation of hydrocarbons and their metabolites.

Administration, Inhalation↗

PubMed1989

Comparison of the circadian rhythm in cell proliferation in corneal epithelium of male rats studied under normal and hypobaric (hypoxic) conditions.

Groups of 20-45-day-old rats maintained on a light (0600-1800)/dark (1800-0600) regimen with food and water available ad libitum were studied for the effect of hypoxic hypoxia on the circadian rhythm of corneal epithelial mitosis and thymidine incorporation. In experiments conducted during the months of September and November, hypoxic hypoxia was accomplished by the exposure of rats to a simulated altitude of 7500 m in one series of experiments, or to a gaseous mixture of 8% oxygen and 92% nitrogen at sea level atmospheric pressure (760 mmHg) in another series of experiments. Controls were included as well. Statistically significant (P less than 0.05) circadian rhythmicity in the corneal mitotic index was substantiated in the control animals with mesor (M) = 12.4%, amplitude (A) = 9.6% and acrophase (phi) of 0911. In the hypoxic hypoxia situation, the mesor and amplitude were depressed to 8.6 and 5.9%, respectively. In control groups, thymidine incorporation was circadian rhythmic with M = 38.5 and A = 11.3 cpm/microns DNA and acrophase of 2255. In the hypoxic hypoxia situation, the mesor was similar to the controls; whereas the amplitude was suppressed to 6.1% and acrophase was phase advanced by about 7 hr. Changes in the circadian rhythm of corneal mitosis and in thymidine incorporation under hypoxic hypoxia can be explained by programmed-in-time energy requirements during the corneal cell regeneration cycle.

Animals↗

PubMed1988