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Biomedical subjects

C H Gallagher

Publications and source records attributed to C H Gallagher.

At least 37 records · Page 2Linked to original sources
PubMed1984

Characterization and histogenesis of tumors in the hairless mouse produced by low-dosage incremental ultraviolet radiation.

Tumors were induced in the HRA/Skh-1 hairless mouse by repeated irradiations of minimally erythemal and suberythemal doses of UV radiation. Aspects of tumor induction were recorded using a combined system of mapping and gross descriptive classification. Tumors of epithelial and dermal (mesenchymal) origin were confirmed histologically and their types correlated well with those reported by earlier investigators. Among those classified, however, appendage tumors and hemangiomas have rarely been described. The progression to malignancy of epithelial tumors was systematically characterized and was a consistent histogenic feature in our experiments. Squamous cell carcinomas represented a final stage for development arising ab initio or from other forms, in particular papillomas which commonly passed through intermediate forms toward definite malignancy. While confirming previous studies of UV-induced tumors, this report extends our knowledge of their dynamics as this bears upon any experimental objective which includes an assessment of tumorigenicity.

Animals↗
PubMed1982

Influence of coenzyme A on the in vitro binding of benzo(a)pyrene metabolites to protein.

Incubation of 20,000 xg supernatants of liver homogenates from female Wistar rats with benzo(a)pyrene (BP) and other cofactors in the presence of coenzyme A (CoA) produced metabolites that required extensive hydrolysis successively in 2N NaOH, 2N HCl, 2N NaOH and 6N HCl for their release. It is suggested that coenzyme A activated benzpyrenyl-amino acid formed via epoxide(s). The activated amino acid(s) became bound to thiol protein.

Animals↗
PubMed1981

Metabolism of [14C]benzo[a]pyrene in vivo in the rat.

[14C]Benzo[a]pyrene ([14C]B[a]P) injected intraperitoneally into rats appeared rapidly in liver, lung and kidney, and remained detectable in these tissues for at least 7 days. A large proportion (7--13%) of the 14 C became covalently bound to tissue macromolecules, probably primarily proteins. Subcellular organelles of the liver were all found to bind the carcinogen, the microsomes most rapidly and the light mitochondrial fraction taking up 14C later. Nuclear bound 14C was detected in both liver and lung. Purification of the cytosolic 14C from liver revealed specific binding to the same cytosolic proteins purified from the in vitro reaction of [14C] B[a]P.

Animals↗
PubMed1976

Interrelationships of copper, cytochrome oxidase, phospholipid synthesis and adenine nucleotide binding.

Studies are reported on the interrelationships in liver mitochondria of copper status, cytochrome oxidase activity, adenine nucleotide binding capacity and phospholipid synthesis. Direct exposure of mitochondria to cyanide or diethyldithiocarbamate depressed cytochrome oxidase activity; ADP-binding and phospholipid synthesis. Fractionation of mitochondria to increase the specific activity of cytochrome oxidase about 10-fold did not increase the affinity to bind ADP. Ageing of mitochondria or dialysis of mitochondria or mitochondrial membrane preparations against water or diethyldithiocarbamate at 0--2 degrees for 18 h did not decrease cytochrome oxidase activity or copper content of reisolated and resuspended mitochondria or mitochondrial membrane preparations, but considerably reduced the affinity to bind ADP. The respiratory inhibitors, fluoride and azide, at concentrations inhibitory to cytochrome oxidase did not reduce ADP-binding or phospholipid synthesis. Atractyloside did not inhibit cytochrome oxidase activity but did inhibit ADP-binding and phospholipid synthesis. Pre-incubation of mitochondrial membrane preparations with Cu++ increased the copper content and ADP-binding affinity. The results indicate that cytochrome oxidase is not the ADP-binding site of the mitochondrial membrane system and that reduced cytochrome oxidase activity per se does not depress binding affinity. Copper appears to be a component of the adenine nucleotide binding sites of mitochondrial membranes because the copper-complexing agents, cyanide and diethyldithiocarbamate, depressed ADP-binding, while increased mitochondrial membrane copper content increased ADP-binding.

Adenosine Diphosphate↗
PubMed1976

Covalent binding to protein of the K-region oxide of benzo(a)pyrene formed by microsome incubation.

Incubation of 20,000 X g supernatant proteins of rat liver with benzo]a]pyrene (BP) and appropriate cofactors produced metabolites of BP covalently bound at the 4,5- position to protein. After being incubated, protein samples were freed from noncovalently bound metabolites and hydrolyzed chemically or both enzymatically and chemically. All steps were performed under minimum exposure to light and air; benzene extracts were prepared during hydrolysis. Chemical hydrolysis released the K-region metabolite BP-4,5-dihydrodiol (identified by UV and mass spectra) and BP. Hydrolysis with trypsin and pronase gave products with the characteristic UV spectrum of substituted chrysene. Chemical hydrolysis of these products released BP and BP-4,5-dihydrodiol.

Animals↗
PubMed1976

Coppr deficiency in the rat. Relationship to chronic cyanide poisoning.

Daily administration of increasing doses intraperitoneally of 2.5-4.0 mg NaCN/kg to male Wistar rats for 5 weeks produced acute signs of poisoning immediately post-injection but no sign of chronic toxicity except lower final body weights than in control rats. CN-treated rats had less liver copper than controls, but not below the range of normality, and their liver mitochondrial membranes were 24% less able to bind adenine nucleotides than control membranes. No other biochemical or pathological sign of copper deficiency occurred. Liver cytochrome oxidase activity was normal after the 5 weeks of CN-administration, as was the ability of liver mitochondria to synthesize phospholipids. The ultrastructure of hepatocytes was normal without evidence of the enlarged, misshapen mitochondria produced by copper deficiency. Normal cytochrome oxidase activity of liver mitochondria, together with reduced liver copper levels and reduced binding affinity of mitochondrial membranes for adenine nucleotides, indicate that the membrane binding site for adenine nucleotides is not cytochrome oxidase per se but may involve copper, perhaps by virtue of its cationicity. With repeated exposure to CN- rats develop tolerance to acute poisoning. It is suggested that this may be due to the switch in glucose catabolism towards the pentose pathway at the expense of other pathways.

Adenosine Diphosphate↗