Carcinogenic effects animal models

In summary, preliminary results from two animal models (rabbit and mouse) indicate that poly(N-palmitoylhydroxyproline ester) elicits a very mild, local tissue response that compares favorably with the responses observed for established biomaterials such as medical grade stainless steel or poly(lactic acid)/poly(glycolic acid) implants. At this point, additional assays need to be performed to evaluate possible allergic responses, as well as systemic toxic effects, carcinogenic, teratogenic, or mutagenic activity, and adaptive responses. 

Curcumin (diferuloyl methane) is the main pigment of turmeric. It is widely used as a colorant and preservative agent. No data regarding its daily intake in western countries are available intake may reach 80 to 200 mg in adult Indians. To date, no study has explored the effect of curcumin consumption on the incidence of diseases, but many beneficial effects on health have been reported in cell and animal models. These include anti-carcinogenic, anti-diabetic, anti-atherosclerotic, and anti-Alzheimer s disease properties. ... 

The database for HFC-134a is extensive it contains studies with both human subjects and animal models. Potentially sensitive populations, including patients with COPD and adult and pediatric asthmatic patients, were tested with direct inhalation of HFC-134a from metered-dose inhalers. The response of these groups was no different than that of healthy adults. The animal studies covered acute, subchronic, and chronic exposure durations and addressed systemic toxicity as well as neurotoxicity, reproductive and developmental effects, cardiac sensitization, genotoxicity, and carcinogenicity. The metabolism of HFC-134a is well understood, and the relationship of exposure con... 

Human beings are more sensitive to the carcinogenic effects of methylene chloride than are the experimental animals used for hazard and dose-response modeling. 

It is possible to use this OH° concentration to predict k for the oxidation of other compounds under the same conditions. Von Gunten et al. (1995) calculated the actual concentration of OH° using this general and easy way for the ozonation of surface water at neutral pH in a two-stage pilot plant. Atrazine was used as the model compound, ozone decay was assumed to be of first order and the reactors completely mixed. Based on this model they were able to precisely predict the formation of bromate (Br03 ) by oxidation of bromide (Br ) for a full-scale water treatment plant. Bromate is a disinfection byproduct (DBP) of the ozonation of bromide-containing waters, and of concern because of its carcinogenic effects in animal experiments (see also Chapter A 3). 

The majority, or as much as 70-90%, of human cancers have been associated with environmental causes ( 1, 2) Our environment is complex. Cancer causes are often misunderstood and misconstrued as consisting primarily of ubiquitous chemicals due to modern technology and industrial development. It is true that a number of food additives, pesticides, insecticides and industrial chemicals introduced commercially in the last 40 years have exhibited carcinogenic properties in animal models ( 3). However, most of the main human cancers in the Western world do not stem from such chemical contaminants. It is, therefore, important to identify the actual causes of cancer in developing an effective basis for cancer prevention. 

Therefore, when it became clearly understood that atrazine is neither estrogenic nor a genotoxic, direct-acting carcinogen - and that the atrazine-associated tumor responses appeared only in female SD rats, a strain with a high, normally occurring incidence of mammary tumors - it became important to study the effect of high doses of atrazine on the SD animal model s own endocrine system and hormonal milieu. 

REACH aims to protect both the environment and human health from the industrial chemicals used in Europe, which refer to tens of thousands of substances. In this case, the ideal systems to be evaluated are human health and environment. However, the legislation defines a series of models, which can be used to assess the effects on these two major systems. Animal models are quite often mentioned, in case of toxicity studies and bioaccumulation. Examples of such models are models using rat and fish. Rat and mouse, typically, are used as models for human health, and fish is useful for environmental endpoints. However, it is well recognized that humans are different from rodents for a series of biochemical processes. To study carcinogenicity, for instance, a battery of tests is common, using rat and mouse, both male and female animals. Differences are often found in the different rodent experiments, and this highlights the problems in extrapolating results to humans. Still, in vivo experiments are a fundamental way to study toxicity. 

The most characteristic toxic effect of benzene in both human and animal models is the depression of the bone marrow, leading ultimately to aplastic anemia (Rozen and Snyder 1985 Snyder and Kocsis 1975 Snyder et al. 1993b). Rozen and Snyder (1985) have noted that abnormalities of humoral and cell-mediated immune responses following benzene exposure of C57BL mice by inhalation are presumably caused by a defect in the lymphoid stem cell precursors of both T- and B-lymphocytes. They also observed that bone marrow cellularity and the number of thymic T-cells increased, presumably as a compensatory response in these cell lines in response to benzene exposure. This compensatory proliferation may play a role in the carcinogenic response of C57BL mice to inhaled benzene. 

The chronic effects of exposure to cyanogen chloride include hoarseness, conjunctivitis, and edema of the eyelid. Short-term fatal concentrations in animal models range from 48 to 500 ppm. The carcinogenic or mutagenic potential of cyanogen chloride is not well characterized. 

The third hypothesis put forth to explain the anti-carcinogenic effects of DR holds that selective removal of initiated cells takes place in DR. It has been shown in the liver tumor model that increased apoptosis and decrease in the rate of cell proliferation in DR animals play an important role in decreasing spontaneous as well as chemical-induced tumors. Similar enhancement in apoptosis has been shown in brain tumor model. The increase in apoptosis is a mechanism devised by the DR animals to cope up with the decreased availability of food. The damaged and weak cells are efficiently removed in the DR animal, which also helps in... 

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