Cancer chemotherapy specificity

The inhibitors of RNA polymerase, which generates RNA from DNA, inhibit a crucial step in gene expression. Inhibition of the eukaryotic form of RNA polymerase is used in cancer chemotherapy and is also an important experimental tool. For example, actinomy-cin D binds to the guanine residues in DNA and blocks the movement of the eukaryotic RNA polymerase. Specific inhibitors of bacterial RNA polymerase can be used as antibacterial agents. Most of these inhibitors like rifamycin bind to the prokaryotic enzyme. 

Poste, G., and Kirsh, R. (1983). Site-specific (targeted) drug delivery in cancer chemotherapy. Biotechnology, 1, 869-878. 

The most important application recently developed for synthetic liposomes is as potential drug carriers for controlled release, especially for cancer chemotherapy (7). In general, the success of liposomes as vehicles for the transport of specific drugs will largely depend on their stability under physiological conditions. Unlike the naturally occurring membranes, the synthetic vesicles have very limited stability, and this is a... 

Since many essential nutrients (e.g., monosaccharides, amino acids, and vitamins) are water-soluble, they have low oil/water partition coefficients, which would suggest poor absorption from the GIT. However, to ensure adequate uptake of these materials from food, the intestine has developed specialized absorption mechanisms that depend on membrane participation and require the compound to have a specific chemical structure. Since these processes are discussed in Chapter 4, we will not dwell on them here. This carrier transport mechanism is illustrated in Fig. 9C. Absorption by a specialized carrier mechanism (from the rat intestine) has been shown to exist for several agents used in cancer chemotherapy (5-fluorouracil and 5-bromouracil) [37,38], which may be considered false nutrients in that their chemical structures are very similar to essential nutrients for which the intestine has a specialized transport mechanism. It would be instructive to examine some studies concerned with riboflavin and ascorbic acid absorption in humans, as these illustrate how one may treat urine data to explore the mechanism of absorption. If a compound is... 

Wacher, V. J., Wu, C. Y., Benet, L. Z., Overlapping substrate specificities and tissue distribution of cytochrome P450 3A and P-glycoprotein implications for drug delivery and activity in cancer chemotherapy, Mol. Carcinogen. 1995, 13, 129-134. 

Wacher VJ, Wu CY and Benet LZ (1995) Overlapping Substrate Specificities and Tissue Distribution of Cytochrome-P450 3a and P-Glycoprotein—Implications for Drug-Delivery and Activity in Cancer-Chemotherapy. Mol Carcinog 13 pp 129-134. 

The fungal metabolites TAN-1496 A, C, and E (isolated from the culture broth of Microsphaeropsis sp. FL-16144) have been shown to have specific inhibitory activity against DNA topoisomerase 1. DNA topoisomerase 1 is an enzyme responsible for DNA metabolism and have been proposed as an intracellular target for cancer chemotherapy. ... 

Screening of microbial products has led to the discovery of a number of growth-inhibiting compounds that have proved to be clinically useful in cancer chemotherapy. Many of these antibiotics bind to DNA through intercalation between specific bases and block the synthesis of RNA, DNA, or both cause DNA strand scission and interfere with cell replication. All of the anticancer antibiotics now being used in clinical practice are products of various strains of the soil microbe Streptomyces. These include the anthracyclines, bleomycin, and mitomycin. 

When cancer is diagnosed, three primary treatment modalities are available surgery, radiation treatment, and cancer chemotherapy. The purpose of this chapter is to describe the basic rationale of cancer chemotherapy and to provide an overview of the drugs that are currently available to treat specific forms of cancer. Rehabilitation specialists will routinely work with patients undergoing cancer chemotherapy. For reasons that will become apparent in this chapter, these drugs tend to produce toxic effects that directly influence physical therapy and occupational therapy procedures. Therefore, this chapter should provide therapists with a better understanding of the pharmacodynamic principles and beneficial effects, as well as the reasons for the potential adverse effects of these important drugs. 

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