Rats were given a single dose of toxaphene (120 mg/kg, equivalent to 1/2 LD50) and sacrificed at 1, 5, and 15 days. Liver weight and hepatic microsomal enzyme activity were increased at day 5 and 15. The level of plasma testosterone was significantly decreased at day 15. In a second experiment rats were given 2.4 mg/kg daily and sacrificed at 1, 3 and 6 months. Liver weight and microsomal enzym...

Recent observations from this laboratory have revealed that there is an alteration in the kinetic properties of microsomal glucose 6-phosphatase in the livers of diabetic rats (1, Z), in addition to the’well established increase in total activity (3, 4). Since the kinetic differences between the normal and the diabetic enzyme disappeared upon disruption of the microsomes (Z), it seemed possible...

A rapid and sensitive indirect enzyme-linked immunosorbent assay (ELISA) was developed for microsomal epoxide hydrolase of rat liver. The assay, which is easily and readily performed, is significantly more sensitive than most enzymatic epoxide hydrolase assays routinely used and electroimmunoassays previously developed. The limit of sensitivity of the ELISA is between 2-5 ng of microsomal epoxi...

The formation of S-nitrosoglutathione (GSNO) from amyl nitrite and n-butyl nitrite was studied in rat liver microsomes, employing N-ethylmaleimide (MalNEt) as an activator and indomethacin as an inhibitor of microsomal glutathione S-transferase (GST). Rates were compared with GST activity measured with 1-chloro-2,4-dinitrobenzene (CDNB) as a substrate. MalNEt stimulated GST activity and the for...

Transgenic tobacco (Nicotiana tabacum cv Xanthi) plants expressing a genetically engineered fused enzyme between rat cytochrome P4501A1 (CYPlAl) and yeast NADPH-cytochrome P450 oxidoreductase were produced. The expression plasmid pCFC2 for the fused enzyme was constructed by insertion of the corresponding cDNA into the expression vector pNCOl under the control of the cauliflower mosaic virus 35...

Further studies of the induction of the liver microsomal drug-hydroxylating enzyme system by pretreatment of rats with various drugs are presented. The phenobarbital-induced increase in the microsomal content of CO-binding pigment and in the activities of TPNH-cytochrome c reductase and the oxidative demethylation of aminopyrine is proportional, within certain limits, to the amount of phenobarb...

Transgenic tobacco (Nicotiana tabacum cv Xanthi) plants expressing a genetically engineered fused enzyme between rat cytochrome P4501A1 (CYP1A1) and yeast NADPH-cytochrome P450 oxidoreductase were produced. The expression plasmid pGFC2 for the fused enzyme was constructed by insertion of the corresponding cDNA into the expression vector pNG01 under the control of the cauliflower mosaic virus 35...

We have studied 250 human liver biopsy samples to determine the ontogeny of the microsomal glucose-6-phosphatase (EC 3.1.3.9) system. Human hepatic glucose-6-phosphatase enzyme activity develops at 11 weeks' gestation and slowly increases to approximately 10% of adult activity at term. In the first week after birth, activity rises to adult values. Increases in enzyme activity coincide with incr...

The present work describes an accurate assay of the rate-limiting enzyme in bile acid synthesis, the cholesterol 7 alpha-hydroxylase, in human liver. The assay is based on isotope dilution-mass spectrometry, and endogenous microsomal cholesterol is used as the only substrate for the enzyme. Operative liver biopsies were obtained from patients undergoing elective cholecystectomy under highly sta...