ISSN:0265-203X    

DOI:10.1080/02652038409385827

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The carcinogenetic risk assessment of veterinary drugs has to be envisaged as part of food toxicology. The authors review the recent discoveries which have proved significant for the toxicologist.

ISSN:0265-203X    

DOI:10.1080/02652038409385828

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Residues of animal drugs with carcinogenic potential cannot always be avoided in food. The risk/benefit evaluation of carcinogenic drugs used in food‐producing animals is a scientifically unresolved problem. Nonetheless, a pragmatic solution taking into account such drugs’ putative mechanisms of action, their relative potency, and their significance in the prevention and therapy of disease must and can be achieved.

ISSN:0265-203X    

DOI:10.1080/02652038409385829

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The nature of at least three stages in carcinogenesis by chemical agents justifies the existence of a threshold dose: (1) a cytoplasmic stage during which most carcinogenic molecules are eliminated, (2) a nuclear stage during which certain DNAlesionsare repaired and therefore cannot help to bring about mutations, and (3) an extracellular stage during which mutations are controlled for a long time by positive or negative epigenetic factors.

ISSN:0265-203X    

DOI:10.1080/02652038409385830

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The oestrogens that are used in husbandry are oestradiol (natural compound), zeranol (non‐steroid drug) and stilbenes such as diethylstilboestrol (D.E.S.).

ISSN:0265-203X    

DOI:10.1080/02652038409385831

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The objective of long‐term carcinogenicity studies is to observe test animals for a major portion of their lifespan for the development of neoplastic lesions during or after exposure to various doses of a test substance given by an appropriate route. Studies of this type require careful planning and documentation of the experimental design, a high standard of pathology, good animal care and suitable statistical analysis. These requirements are well known and have not undergone major changes during recent years. Rather than giving details of these requirements, which can now be found in many publications, this paper attempts to indicate some of the problems involved in a long‐term carcinogenicity study.

ISSN:0265-203X    

DOI:10.1080/02652038409385832

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The various mathematical models of the dose‐response relationship are briefly reviewed and it is concluded that the Weibull and gamma‐multihit models are at present the best ones. They permit the computation of a ‘virtually safe dose’, for which the carcinogenic risk to man is reasonably negligible, but because of the unknown mechanism of the background response, the models should be used in a mixed form. A modified Crouch and Wilson approach is proposed to evaluate the risk from an actual environmental dose. This takes into account the various uncertainties in risk computations, and results in the application of a safety factor when extrapolating from animals to man.

ISSN:0265-203X    

DOI:10.1080/02652038409385833

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Most toxic Chemicals undergo bioactivation before they can exert their noxious effects. These biotransformations produce very reactive intermediate metabolites which covalently bind to vital cellular components and can lead to a specific toxicity.

ISSN:0265-203X    

DOI:10.1080/02652038409385834

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

ISSN:0265-203X    

DOI:10.1080/02652038409385835

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Thein vivointeractions of trenbolone and zeranol with rat‐liver DNA were assayed by determining their covalent‐binding indices (CBI), which correlate well with the hepatocarcinogenic potencies of chemicals. As controls, 17ß‐oestradiol and testosterone were used. Sixteen hours after intraperitoneal injection of the [3H]‐labelled compounds (specific radioactivity ∼50 Ci/mmol) the animals were sacrificed and the DNA was isolated from the livers and deproteinized by several Sevag extractions and proteinase digestion. Contaminating RNA was eliminated by pancreatic RNAase digestion. Finally, the DNA was further purified by chromatography on hydroxylapatite and by centrifugation in a CsCl gradient. Decreased CBI values after each step of purification showed that extensive purification was essential.

ISSN:0265-203X    

DOI:10.1080/02652038409385836

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor