Results 261 to 270 of about 327,951 (318)
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Regulatory Toxicology and Pharmacology, 1995
For decades, it has been known that a number of different factors (e.g., species, metabolism, age, animal husbandry, diet) may exhibit a significant modulating effect on the process of carcinogenesis. Often, however, these modulators have been largely uncontrolled and thus have made uncertain the results of many carcinogenicity bioassays.
I C, Munro +3 more
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For decades, it has been known that a number of different factors (e.g., species, metabolism, age, animal husbandry, diet) may exhibit a significant modulating effect on the process of carcinogenesis. Often, however, these modulators have been largely uncontrolled and thus have made uncertain the results of many carcinogenicity bioassays.
I C, Munro +3 more
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Die Naturwissenschaften, 1975
An examination has been made of the major chemicals which are known to be carcinogenic, either in animals or in humans. As a result, a generalized type of chemical property seems to be a prerequisite for the carcinogenic activity. In most cases, this is some kind of reactive electrophilic intermediate produced directly from the carcinogen or from one ...
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An examination has been made of the major chemicals which are known to be carcinogenic, either in animals or in humans. As a result, a generalized type of chemical property seems to be a prerequisite for the carcinogenic activity. In most cases, this is some kind of reactive electrophilic intermediate produced directly from the carcinogen or from one ...
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Cancer Investigation, 1987
The importance of mutations in carcinogenesis is still unclear. Assuming that mutations of the genetic material are central to this problem, the number needed to give rise to a cancer cell must be established. A one-mutation theory is unsatisfactory for a number of reasons. A four-mutation model fits better and can be calculated in humans assuming that
W, den Otter +2 more
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The importance of mutations in carcinogenesis is still unclear. Assuming that mutations of the genetic material are central to this problem, the number needed to give rise to a cancer cell must be established. A one-mutation theory is unsatisfactory for a number of reasons. A four-mutation model fits better and can be calculated in humans assuming that
W, den Otter +2 more
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Seminars in Oncology Nursing, 1992
The rationale for identifying carcinogens and their mechanisms of action is twofold. First, carcinogens must be identified so they can be eliminated from our environment. And second, mechanisms must be identified that are involved in the conversion of a normal cell to a cancer cell. This knowledge will offer more approaches to cancer prevention.
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The rationale for identifying carcinogens and their mechanisms of action is twofold. First, carcinogens must be identified so they can be eliminated from our environment. And second, mechanisms must be identified that are involved in the conversion of a normal cell to a cancer cell. This knowledge will offer more approaches to cancer prevention.
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Cancer, 1975
The field of chemical carcinogenesis is reviewed, with emphasis on three aspects: 1) environmental chemicals are a major cause of human cancer; 2) most chemical carcinogens require metabolic activation by mixed-function oxidases to electrophilic metabolites that form strong covalent chemical bonds with cellular macromolecules and thereby initiate the ...
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The field of chemical carcinogenesis is reviewed, with emphasis on three aspects: 1) environmental chemicals are a major cause of human cancer; 2) most chemical carcinogens require metabolic activation by mixed-function oxidases to electrophilic metabolites that form strong covalent chemical bonds with cellular macromolecules and thereby initiate the ...
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Experimental Pathology, 1981
Figure 2 illustrates a suggested mechanism of carcinogenesis. This scheme takes into account the effect of carcinogens at different integration levels: subcellular, tissue, and organism. Any of these levels may be age dependent. Age-associated changes in the activity of enzymes responsible for activation and inactivation of carcinogens, and variations ...
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Figure 2 illustrates a suggested mechanism of carcinogenesis. This scheme takes into account the effect of carcinogens at different integration levels: subcellular, tissue, and organism. Any of these levels may be age dependent. Age-associated changes in the activity of enzymes responsible for activation and inactivation of carcinogens, and variations ...
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Journal of Steroid Biochemistry, 1975
Abstract The unopposed continuous administration of biologically active estrogenic materials produces a wide variety of cancers in experimental animals. Most of these cancers occur in the target tissues for estrogenic activity and appear to be characteristic of the animal rather than the estrogens.
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Abstract The unopposed continuous administration of biologically active estrogenic materials produces a wide variety of cancers in experimental animals. Most of these cancers occur in the target tissues for estrogenic activity and appear to be characteristic of the animal rather than the estrogens.
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Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis, 2004
Traditional views of nutritional carcinogenesis depend on the identification of exogenous carcinogens as major risk factors. As our understanding evolves, it is clear that the pattern of events involves not only exogenous carcinogens, but also metabolic processes and endogenous and exogenous anticarcinogens.
Andrew R, Collins, Lynnette R, Ferguson
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Traditional views of nutritional carcinogenesis depend on the identification of exogenous carcinogens as major risk factors. As our understanding evolves, it is clear that the pattern of events involves not only exogenous carcinogens, but also metabolic processes and endogenous and exogenous anticarcinogens.
Andrew R, Collins, Lynnette R, Ferguson
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Journal of Toxicology and Environmental Health, 1980
In radiation-induced carcinogenesis the stages of initiation, transformation, and promotion can be identified. Radiation carcinogenesis is a stochastic phenomenon that does not exhibit any threshold in the dose-response relationship. The most important risk to be controlled is that of the population--either industrial or medical--exposed to radiation ...
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In radiation-induced carcinogenesis the stages of initiation, transformation, and promotion can be identified. Radiation carcinogenesis is a stochastic phenomenon that does not exhibit any threshold in the dose-response relationship. The most important risk to be controlled is that of the population--either industrial or medical--exposed to radiation ...
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Langenbeck's Archives of Surgery, 2011
In most patients, gastric cancer is diagnosed in advanced stage. Curative treatment options are limited and the mortality is high. The process of gastric carcinogenesis is triggered by Helicobacter pylori-driven gastritis and is further characterized by its complexity of interaction with other risk factors.
Jan, Bornschein, Peter, Malfertheiner
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In most patients, gastric cancer is diagnosed in advanced stage. Curative treatment options are limited and the mortality is high. The process of gastric carcinogenesis is triggered by Helicobacter pylori-driven gastritis and is further characterized by its complexity of interaction with other risk factors.
Jan, Bornschein, Peter, Malfertheiner
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