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Biomedical subjects

R Borgia

Publications and source records attributed to R Borgia.

13 recordsLinked to original sources
PubMed1991

Effect of enzyme inducers on metabolism of 1-nitropyrene in human hepatoma cell line HepG2.

We measured the response of HepG2 cells to the classic cytochrome (cyt.) P-450 inducers 3-methylcholanthrene (3-MC) and phenobarbital (PB), by evaluating oxidative and/or reductive metabolism of the nitroarenes, 1-NP and 1,6-dinitropyrene (1,6-DNP), in control and induced cells. In HepG2 cells, 3-MC induces ring-hydroxylation of 1-NP, whereas PB stimulates its nitroreduction. PB induces NADPH-cyt. c reductase, but does not affect other cytosolic and microsomal enzymes which contribute to 1-NP nitroreduction in these cells. However, PB-inducible nitroreductase activity seems to be associated primarily with cyt. P-450 isoenzymatic form(s), as indicated by the requirement for NADPH and the response to specific inhibitors such as alpha-naphthoflavone and CO.

Carcinoma, Hepatocellular↗
PubMed1988

Induction of hepatic drug-metabolizing enzymes in rats treated with 1-nitropyrene.

The inducing effects of 1-nitropyrene (1-NP) on the microsomal cytochrome P-450 system were studied in rats. Intraperitoneal administration of 1-NP led to increases in cytochrome P-450 content and aryl hydrocarbon hydroxylase, ethoxycoumarin, and ethoxyresorufin-O-deethylase activities. These increases were dose dependent. Cytochrome b5 content and aminopyrine and p-nitroanisole demethylase activities were not affected by treatment of rats with 1-NP. Substrate specificity, sensitivity to mixed-function oxidase inhibitors, and electrophoretic pattern of 1-NP-induced cytochrome(s) P-450 were compared to the major forms of cytochrome P-450 induced by phenobarbital and methylcholanthrene. Furthermore microsomes from 1-NP-induced rats showed greater ability to metabolize the chemical as compared with those from control animals; this result indicates that 1-NP induces a form(s) of cytochrome P-450 especially effective in the metabolism of the substance itself.

Animals↗
PubMed1983

Treatment of chronic constipation by a bulk-forming laxative (Fibrolax).

Seventy-five patients affected by chronic constipation were treated for 4 weeks with an Ispaghula Husk preparation (Fibrolax), a bulk-forming laxative. Frequency, stool consistency, abdominal pain and signs of venous stasis improved after treatment. No important side-effect was recorded. Cholesterol, HDL-cholesterol and triglycerides did not show significant changes.

Adult↗
PubMed1980

Fibrin clot retractile activity of mouse fibroblasts during growth and aging.

This study aimed at evaluating by a quantitative assay the fibrin clot retractile activity (FCR) of C3H embryo fibroblasts during their growth and aging in culture. Cell from primary and subsequent subcultures were tested at defined times from seeding, in a specially devised micromethod. Results indicate that cell-induced FCR has a kinetic similar to platelet-induced FCR; it depends on the number of cells and time of incubation in the system. It is absent or low in cells harvested from primary culture, then increases and remains high in the following doublings decreasing sharply at the end of the replicative life span in culture.

Animals↗
PubMed1980

Polycyclic hydrocarbons induction of diphtheria toxin-resistant mutants in human cells.

Stable spontaneous mutants resistant to diphtheria toxin are present in the human cell line (EUE) at a frequency of 0-8 x 10(-6). Mutation increases by a number of polycyclic hydrocarbons have been used as an estimate of their carcinogenic potency. Eight polycyclic hydrocarbons of decreasing carcinogenic potency were assayed: 7,12-dimethylbenz[a]anthracene, 3-methylcholanthrene, benzo[a]pyrene, benz[a]anthracene, dibenz[a,c]anthracene, dibenz[a,h]anthracene, chrysene, anthracene, and a well known mutagenic substance, ethyl methanesulfonate. In our system, which does not require an exogenous source for metabolic activation, the most potent hydrocarbons, 7,12-dimethylbenz[a]anthracene, 3-methylcholanthrene and benzo[a]pyrene revealed a strong mutagenic effect, whereas three non-carcinogenic hydrocarbons, anthracene, benz[a]anthracene and chrysene were not mutagenic. Our results indicate that there is a relationship between mutagenesis and carcinogenic potency for the tested polycyclic hydrocarbons. The maximum recovery of diphtheria toxin mutants was observed after an expression time of three weeks, corresponding to 10 cell generations.

Biotransformation↗
PubMed1979

An actin-destabilizing factor is present in human plasma.

Plasma and serum of humans or experimental animals contain a factor which destabilizes F-actin. The factor has no DNAse or thrombin activity and after incubation with F-actin does not modify the position of the actin band on a SDS polyacrylamide gel. Hence it probably depolymerizes F-actin.

Actins↗