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Biomedical subjects

E Bresnick

Publications and source records attributed to E Bresnick.

At least 127 records · Page 7Linked to original sources
PubMed1978

The ontogeny of nuclear aryl hydrocarbon hydroxylase.

The ontogeny of rat liver nuclear aryl hydrocarbon hydroxylase (AHH) ws studied. AHH which was barely detectable in 18--20 day fetal rat liver nuclei increased rapidly post-partum reaching a value which was over 200 times greater than the fetal liver specific activity. Nuclear AHH was induced upon administration of 3-methylcholanthrene (3-MC) to rats. The level of induction was dependent upon the age of the rat. Thus, the highest induced nuclear AHH specific activity was observed in the 3--4-week-old rat, i.e., 50--70 g in weight. The greatest fold increase in nuclear AHH after 3-MC administration was observed in the 6--8 g, or 1--2-day-old rat. Fetal rat liver nuclear AHH was also induced after 3-MC administration to the dam. The basal and induced levels of AHH were compared in nuclei and microsomes from 1--2 and 10--12-day-old rats. In the former, the ratio of the microsomal to nuclear AHH was 1.4 and 1.8 under basal and induced conditions, respectively.

Aging↗
PubMed1978

Effects of diethyl maleate on aryl hydrocarbon hydroxylase and on 3-methyl-cholanthrene-induced skin tumorigenesis in rats and mice.

Topical administration of diethyl maleate (DEM) and L-methionine sulfoximine (MS) reduced the L-glutathione (GSH) levels in kidneys, livers, and skin of inbred BALB/c mice. Topical administration of DEM to BALB/c mice also increased the latency period before development of skin tumors that were induced by 3-methylcholanthrene painting. Similar treatment with MS also increased the latency period, though the delay was not as striking as that observed after DEM administration. Furthermore, DEM, which was believed to be specific in its action in reducing tissue GSH, was also capable of inhibiting aryl hydrocarbon hydroxylase (AHH) both in vitro and in vivo. Cyclohexene sulfide, another "specific" inhibitor of GSH transferase, inhibited AHH activity as well. Accordingly, the blockade of AHH by DEM may have been partly responsible for the increased latency time in the skin tumorigenesis experiments.

Animals↗
PubMed1978

Inability of vitamin A deficiency to alter benzo(a)pyrene metabolism in Syrian hamsters.

Syrian golden hamsters were placed on a control or vitamin A-deficient diet. When their serum vitamin A content was significantly reduced, i.e., to less than 10% of controls, the hamsters were killed and lung aryl hydrocarbon hydroxylase activity and metabolism of benzo(a)pyrene were determined. The benzo(a)pyrene metabolite profile was similar with control and A-deficient systems, and only few quantitative differences were noted. Addition of beta-retinyl acetate to the in vitro incubations did not substantially affect benzo(a)pyrene metabolism.

Animals↗
PubMed1977

Aryl hydrocarbon hydroxylase in mouse mammary gland: in vitro study using mammary cell lines.

The effects of 3-methylcholanthrene (MCA), 5,6-benzoflavone (betaNF), 7,8-benzoflavone (alphaNF) and pregnenolone 16alpha-carbonitrile (PCN) upon aryl hydrocarbon hydroxylase (AHH) were determined in primary mammary gland epithelial cell cultures prepared from the C3Hf-/Ki mouse. MCA elevated AHH activity by 3--4 fold after 24 h of treatment; alphaNF produced a 50% inhibition. The specific activity of AHH in these cells was elevated by 6 h after exposure to MCA; enzyme activity was still maximally elevated after 48 h. The effects of MCA were also investigated in a group of mammary cell lines, one of which was derived from a control virgin mouse, the MCG V14; 3 of which arose from mammary tumors, MCG T10, MCG T14 and MCG T19; and 2 of which were sublines developed from hyperplastic alveolar nodules, HAN-1 and HAN-2. Induction was seen in all lines at 24 h, with the MCG T14 being the most responsive and the HAN-2, the least. Although the MCG T19 tumor cells did respond in culture, when implanted in the mouse, the AHH of the subsequent tumor was not elevated upon administration of MCA in vivo.

Animals↗
PubMed1977

Epidermal hyperplasia after topical application of benzo (a) pyrene, benzo (a) pyrene diol epoxides, and other metabolites.

The effects of benzo(a)pyrene (BP) and 22 derivatives upon the number of nuclei per unit length of epidermis, the number of cell layers of epidermis, and the thickness of the epidermal layer were studied. Several derivatives of BP induced changes in epidermal morphology that are typical of those produced by various agents that promote skin tumorigenesis after application of an initiator. The most potent compounds tested were the BP diol epoxides, (+/-)-7beta,8alpha-dihydroxy-9beta, 10beta-epoxy-7,8,9,10-tetrahydrobenzo-(a)pyrene (diol epoxide 1) and (+/-)-7beta,8alpha-dihydroxy-9alpha, 10alpha-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene (diol epoxide 2). These derivatives were followed in activity by 9-hydroxybenzo(a)pyrene, 2-hydroxybenzo(a)pyrene, and by 9,10-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene. The possible implications of these results with regard to the carcinogenicity of BP on mouse skin are discussed.

Administration, Topical↗
PubMed1976

The formation of poly A-containing RNA in rat liver after administration of 3-methylcholanthrene.

The incorporation of [32P] orthophosphate into liver poly A-rich cytoplasmic RNA was investigated in rats which were pretreated with 3-methyl cholanthrene (3MC) or with the vehicle, corn oil. This incorporation was markedly increased within 6 h after administration of the polycyclic hydrocarbon and reached a maximum by 24 h, i.e., 33-fold increase. The poly A-rich RNA fraction was examined by gel electrophoresis and the specific activity of individual species was shown to be elevated.

Animals↗
PubMed1976

Mouse liver and lung glutathione s-epoxide transferase: effects of phenobarbital and 3-methylcholanthrene administration.

The effects of 3-methylcholanthrene (3MC) and phenobarbital (PB) administration on the levels of glutathione-S-epoxide transferase activity in supernatant preparations of liver and lung were studied in a number of different strains of mice, C57Bl/6, C3H, C3H-f, Balb/c-, A+ and DBA/2+. Three epoxide substrates, 3MC-11,12-oxide, styrene oxide (SO) and 3,3,3-trichloro-1,2-epoxypropane (TCPO), were employed in this investigation. PB administration (75 mg/kg body weight for 3 days) resulted in 13-57% increases in enzyme activity in the liver supernatant but was ineffective in inducing activity in lung. 3MC administration (40 mg/kg body weight for 2 days) on the other hand was without any effect on glutathione-S-epoxide transferase activity in both liver and lung.

Animals↗
PubMed1976

Glutathione-S-epoxide transferase in mouse skin and human foreskin.

Glutathione-S-epoxide transferase activity in skin was determined in six mouse strains as well as in human foreskin (from 2- to 4-day-old neonates) using two substrates, styrene oxide and 3-methylcholanthrene-11,12-oxide. Of the strains used in this study, the highest enzyme activity was noted in the skin of the Balb/c mouse. The enzyme was not inducible in skin by prior administration of 3-methylcholanthrene to the mice. Human foreskin activity was lower than that present in the adult mouse skin and ranged from 1.93 to 5.28 with styrene oxide (at 22 degrees C) and 0.17 to 0.46 nmoles/mg protein/5 min with 3-methylcholanthrene-11,12-oxide (at 37 degrees C) as substrates.

Animals↗
PubMed1976

Glutathione-S-epoxide transferase activity during development and the effect of partial hepatectomy.

The specific activity of glutathione-S-epoxide transferase with styrene oxide and 3-methylcholanthrene-11, 12-oxide was determined in rat liver and lung during development from the fetal to the adult stage and after partial hepatectomy. Enzyme activity in fetal liver or lung at 18 days of gestation was about 20% of that observed in the adult; it rose rapidly to the adult value by 21 days of age. Hepatic enzyme activity was reduced to 50% of control values by 12 hr after partial hepatectomy; enzyme activity returned to control values by 48 hr. No diurnal variation in the activity of glutathione-S-epoxide transferase was observed in rat liver.

Animals↗
PubMed1976

Breakage of human cell DNA after exposure to 3-methylcholanthrene-11,12-oxide.

Damage to and repair of DNA isolated from human neonatal and fetal skin cells were measured by alkaline sucrose gradient analysis. 3-Methylcholanthrene did not induce single-strand breaks in DNA of the cells in culture, whereas the 11,12-oxide of 3-methylcholanthrene was very effective in this regard. The cis-1,2-dihydroxy, trans-11,12-dihydroxy, and cis-11,12-dihydroxy derivatives of 3-methylcholanthrene exerted little effect. The breaks in DNA caused by 3-methylcholanthrene oxide occurred during a 60-min incubation period and were repaired during the following 60 min. Methylmethane sulfonate also induced breaks in the DNA within 60 min.

Cells, Cultured↗