Polyadenylate-polyuridylate enhancement of 7,12-dimethylbenz-anthracene skin carcinogenesis

Summary Double-stranded polynucleotide polyadenylate-polyuridylate (Poly AU) enhanced skin tumor formation in Swiss mice by 75% when injected prior to a single application of 7,12-dimethylbenzanthracene (DMBA). When given after the carcinogen application Poly AU did not significantly enhance tumor formation.Acknowledgment. The authors wish to thank J. Rowland for technical help.     

Mast cell reaction during chemical skin carcinogenesis of the lizardLacerta agilis

Zusammenfassung Beschreibung der Mastzellenreaktion während der chemisch-induzierten Carcinogenese bei der EidechseLacerta agilis.     

Epidermal growth factor enhancement of skin tumor induction in mice

Summary Subcutaneous injection of epidermal growth factor 1. significantly shortened the latency period for the appearance of methylcholanthrene induced skin tumors and 2. increased the average number of papillomas elicited per mouse in both the Swiss Webster and C3HeB/FeJ strains.Acknowledgments. This research was supported by USPHS NCI Grant No. CA 15276 and Contract No. GEN-12 between the Regents of the University of California and the U.S. Energy Research and Development Administration. We thankIlmar Lepik for his assistance in some phases of these experiments.     

Copper acetate as an accelerator in mouse skin carcinogenesis by 9,10-dimethyl-1,2-benzanthracene

Résumé Une solution de l'oxyacétate de cuivre n'est pas cancérigène pour la peau de la souris blanche. L'acétate n'est ni un initiator ni un promoter pour la cancérisation par 9,10-diméthyl-1,2-benzanthracène. Cependant, le traitement des animaux avec l'acétate pendant 10 semaines puis avec l'hydrocarbure augmente la production des tumeurs.     

Dietary carotenoids block photocarcinogenic enhancement by benzo (a)pyrene and inhibit its carcinogenesis in the dark

The carotenoids beta-carotene (C) and canthaxanthine (CX), with and without pro-vitamin A activity, respectively, when perorally administered to mice, markedly prevent benzo(a)pyrene photocarcinogenic enhancement (BP-PCE), continue to block such BP-PCE and protect significantly against BP carcinogenesis in mice maintained in the dark. These results appear relevant to both the pathogenesis of chemical carcinogenesis and rational programs of skin cancer prevention in humans.     

Lack of effect of butylated hydroxytoluene on dimethylhydrazine-induced colon carcinogenesis in rats.

Rats were given 6600 ppm of butylated hydroxytoluene (BHT) in the diet along with 10 weekly oral doses of dimethylhydrazine (DMH, 30 MG/KG). The incidence and mean number of colonic tumors produced were similar to that of rats given DMH alone. Thus, BHT did not provide any protective effect against colon carcinogenesis.     

Radiation carcinogenesis in experimental animals

Summary Exposure of man to relatively high doses of ionizing radiation is generally restricted to accidental situations, with very limited knowledge about the actual doses received. Animal experiments can be performed under standardized and controlled conditions and can provide information on the dose-response relationships for radiation carcinogenesis.The risk of inducing neoplastic late effects after total-body irradiation with relatively high doses has been demonstrated for larger animals, such as monkeys and dogs. The bone marrow, the mammary glands and the lungs are among the tissues with the highest susceptibility for radiation carcinogenesis. Experimental results on tumour induction in rodents are summarized with emphasis on the effectiveness in dependence on radiation quality and fractionation or dose rate.     

Kinetic study of carcinogenesis. The immune barrier and the stability of microcancer states]

We show that cancerisation presents some similarities with first order phase transitions. We analyze the barrier opposed by cytoxic cells against the proliferation of cancer cells.     

Short term tests of carcinogenesis. Evaluation, predictive values, and diverse strategies]

The concepts of validation, evaluation and predictive values of short term tests for carcinogenicity are rigorously defined. The relationships between the parameters measuring these concepts are established. This allows and estimation of the practical efficiency of Ames Salmonella test (1). A new strategy for the evaluation of tests is proposed.     

Thyroiditis in Buffalo strain rats ingesting 7,12-dimethylbenz(a)anthracene

Zusammenfassung Bei männlichen und weiblichen Ratten des Buffalo-Stammes trat nach Verabreichung von 7,12-Dimethylbenzanthracen eine Thyroiditis auf.     

Effects of reserpine on development of 7,12-dimethylbenzanthracene induced mammary tumors in female rats

Résumé Si l'on injecte de la réserpine à des rates avant de les avoir traitées au carcinogène, leurs tumeurs mammaires diminuent très nettement. En revanche, si l'injection de réserpine s'opère chez des rates déjà atteintes de ces tumeurs, la croissance de ces dernières en est sensiblement stimulée.

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Supported in part by NSF research grant GB No. 17034 and NIH research grant No. CA-10771.     

Morphogenetic and cytogenetic effects of 7,12-dimethylbenz(a)anthracene onHaworthia callus in vitro

Zusammenfassung 7,12-Dimethylbenz(a)anthracen (DMBA) in verschiedenen Konzentrationen anstelle von Auxin, Kinetin und Kokosmilch im Nährmedium induziert die Bildung von Wurzeln und beblätterten Sprossen auf den Kalli vonHaworthia variegata. Dieses Ergebnis gleicht demjenigen im vollständigen Kontrollmedium ohne DMBA, mit dem Unterschied, dass unter dem Einfluss von DMBA weniger Sprosse und eine grössere Anzahl von Wurzeln gebildet werden. Cytologische Untersuchungen an Kallus- und Wurzelzellen aus dem DMBA-Medium zeigten eine normale Konstitution des Chromosomensatzes ohne chromosomale Aberrationen.

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This study was supported in part by a summer research grant from Lafayette College Faculty Research Funds.     

The mitigating effect of dietary antioxidants on chemically-induced carcinogenesis

Summary The effect of a dietary antioxidant mixture on 3-methylcholanthrene mediated carcinogenesis in hairless mice was investigated. The antioxidant mixture significantly reduced the frequency of premalignant lesions and their subsequent development into tumors. The similarities in response of chemical and UV light-carcinogenesis to these antioxidants suggest some congruity in the mechanisms of the carcinogenic process.This investigation was supported by National Research Service Award 1 F32 CA05062, awarded by the National Cancer Institute, DHEW and USPH grant CA13464 from the NCI, DHEW. We thank Dr John I. Thornby for statistical analysis of the data.