Cytotoxic chemicals

Mean arterial pressure and cardiac output, an expression of the amount of blood that the heart pumps each minute, are the key Indicators of the normal functioning of the cardiovascular system. Mean arterial pressure is strictly controlled, but by changing the cardiac output, a person can adapt, e.g., to increased oxygen requirement due to increased workload. Blood flow in vital organs may vary for many reasons, but is usually due to decreased cardiac output. However, there can be very dramatic changes in blood pressure, e.g., blood pressure plummets during an anaphylactic allergic reaction. Also cytotoxic chemicals, such as heavy metals, may decrease the blood pressure. 

Another way in nature to protect various forms of life is the formation of spores. Many bacteria, fungi, plants, algae, and protozoan are known to form spores as a strategy to survive for extended periods of time in unfavorable conditions. The high resistance of spores to chemical and physical agents is explained by their multilayered structure (Fig. 3.6). This structure is practically impermeable for cytotoxic chemicals. Besides, endospores have only 20-30% of the water content of vegetative cells... 

Fifth, because of the different types of effects through which radiation and cytotoxic chemicals can influence carcinogenesis at high... 

Thus, cytotoxic chemicals can act as promoters. Indeed chronic inflammation itself can lead to the proliferation of cells. TP A stimulates inflammation via PKC and TNF-cc, which cause the accumulation of inflammatory cells. 

CYTOTOXIC CHEMICALS. Chemical agents that damage cells to which they arc applied. They are poisons, to which cells respond with injury, disease, or death. There are multitudes or cytotoxic chemicals they act by a variety of mechanisms and they have many different kinds of effects. See also Carcinogens. 

Many of these cytotoxic chemicals find application in treating various forms of cancer, but it must be remembered that they all also alfccl normal cells and their introduction io body organs can only be treated with great care and even apprehension. 

IVu.ue.t and pollution— carcinogens, cytotoxic chemicals, dioxin, biphenyls, air pollution, water treatment and pollution, radioactive waste handling. 

If a cytotoxic chemical is capable of being absorbed across the stratum corneum barrier, it has the potential to cause toxicity to the skin. Chemical-induced damage... 

If a cytotoxic chemical is capable of traversing the stratum corneum, it may cause toxicity to the skin as a function of its inherent potential to modify cellular function. Complex quantitative structure activity relationship (QSAR) models developed to assess general cytotoxicity may be applicable to define this inherent toxic potential. The clearest approach to assessing chemical-induced damage to skin is to assess what abnormalities occur when the specific anatomical structures discussed above are perturbed after exposure to topical compounds, since this will be the response modeled in a computational toxicology exercise. 

The activation of protein kinase C and subsequent induction of cell proliferation by cytotoxic chemicals has been suggested by Roghani et al. (64). The inappropriate activation of this enzyme by a chemical-receptor complex is believed to play a role in the promotion process. The activation of protein kinase C may subsequently result in the activation of a number of cytoplasmic proteins through inductional phosphorylation and set off a chain of events which includes enhanced cell proliferation in the absence of regenerative cell replication. The distinction between cytotoxicity and promotion may not always be clear. As recently discussed by Trump and Berezesky (65), chemically-induced alterations in the cellular dynamics of calcium regulation may result in a wide range of changes, many of which are similar to those caused by protein kinase C... 

Of particular significance to toxicology is that a chemical with a mechanism of action that requires interaction with an active metabohc process may only exert toxicity when hair growth is in an active growth phase. Exposure at other times may not elicit any response. Many cytotoxic chemicals (e.g., cancCT chemotherapeutic drugs and immunosuppressants such as cyclophosphamide) with a mechanism of action that is to kill dividing cells will produce hair loss (alopecia) as an imwanted side effect of nonselective activity. 

CaUeja, M. C., Persoone, G., Geiadi, P. (1994) Comparative acute toxicity of the first 50 multicenter evaluation of in vitro cytotoxicity chemicals to aquatic nonvertebrates. Archives Enviommental Contamination and Toxicology 26 69-78. 

Safety/Toxicity Cytotoxicity,chemical toxicity, hepatotoxicity, nephrotoxicity ... 

Tumor cells possess a range of inherited phenotypic features that distinguish them from normal cells. They acquire the ability to undergo almost continual unregulated growth, resist cytotoxic chemicals and are able to... 

Natural products have been created by various organisms as secondary metabolites and the organisms with these cytotoxic chemical weapons can siuvive in the biochemical warfare over billion years. The organisms we observe today are the survival of the fittest, and natural products isolated from these organisms can have such a diverse biological activity, especially excellent cytotoxicity that is the reason why most of anticancer agents and antibiotics have originated from natural products. However, natural products were not as effective as in other therapeutic areas such as type 2 diabetes, depression, osteoporosis ... 

Intestinal operations Food intake Mucosal damage Miscellaneous Resection, bypass, transposition Fasting, refeeding, hyperphagia, parenteral nutrition Irradiation, cytotoxics, chemical carcinogens Hormones, lactation, hypothermia... 

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