Chemotherapy biological considerations

Electrochemistry plays an increasingly important role in biology and medicine and the electrochemical treatment of tumors (ECT) is receiving considerable attention as a viable alternative to the more classical tumor treating approaches of surgery and chemotherapy. Dr. A. Vijh, a specialist in this area, describes both the phenomenology and the proposed physicochemical mechanisms of ECT in a comprehensive chapter. 

The fifth chapter, Tetrahydrobiopterin and Related Biologically Important Pterins by Shizuaki Murata, Hiroshi Ichinose and Fumi Urano, describes a modern aspect of pteridine chemistry and biochemistry. Pteridine derivatives play a very important role in the biosynthesis of amino acids, nucleic acids, neurotransmitters and nitrogenmonooxides, and metabolism of purine and aromatic amino acids. Some pteridines are used in chemotherapy and for the diagnosis of various diseases. From these points of view, this article will attract considerable attention from medicinal and pharmaceutical chemists, and also heterocyclic chemists and biochemists. 

Smptisingj, despite their use for over a quarter of a century, the mechanism of action and the identity of the actual biologically active molecules of most leishmaniasis drugs are not completely understood (for a recent review, see te 37). It does seem clear that, as is the case with most antibiotics, they work best in conjunction with the host s ability to mount appropriate immune responses. In Idshmaniasis, the induction of IL-10, aTh2 type cytokine, has been associated with poor response to chemotherapy. This may be an important consideration in the context of drug development, because some forms of leishmaniasis ate associated with deleterious host responses. 

From a biological perspective the bleomycin (BLM) family of antibiotics that are used widely in chemotherapy, have stimulated considerable effort in understanding oxygen activated iron complexes. In particular iron bleomycin reacts with oxygen to form the so-called purple species, which exhibits an absorption band around 600 nm that is now known to be characteristic of the Fe -OOH species. In the case of Fe-BLM the active intermediate has been identified spectroscopically as a low-spin Fe -hydroperoxide. Several structural mimics of the metastable purple Fe -OOH species have been prepared, in particular complexes with neutral pentadentate ligands e.g., l,l-di(pyiidin-2-yl)-N,N-bis(pyridin-2-ylmethyl)-ethanamine (N4Py) Resonance Raman spectroscopy has proven... 

The unique, considerably dynamic and thus complex physiology of tumors can markedly influence the therapeutic response to standard irradiation, chemotherapy, photodynamic therapy, endocrine therapy and immunotherapy. Acquired treatment resistance due to the impact of the hostile microenvironment adds to the classical drug resistance based on the molecular biology of tiunors. 

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