Pathogenic agents

• pharmacocinetics
  26 March 2006

  Definition: The study of the time course of a drug and its metabolites in the body after administration by any route.

• pharmacodynamics
  26 March 2006

  Definition: The study of the biochemical and physiological effects of drugs and their mechanisms of action.

• amifostine
  20 March 2006

  Amifostine is a sulphydryl antioxidant compound. It has been shown to protect certain normal tissues from the toxic effects of radiotherapy and several cytotoxic drugs, both in animal models and clinical studies.
  Amifostine is believed to scavenge free radicals, disarm radicals on membranes and DNA, and form mixed disulphides to protect normal cells.
  The selectivity, in terms of protection of normal tissues, is assumed to be connected to the perfusion-related distribution and absorption (...)

• chemoprotection
  20 March 2006

  The terms ’chemoprotection’ or ’radioprotection’ refer to the protection of normal cells from the toxicity of cancer chemotherapeutic agents or radiotherapy.
  As the concentration of oxygen and thiols in the vicinity of the DNA has a marked effect on the cellular radiosensitivity, pharmacological modulation of oxygenation in the normal cells has been used as an approach to protect normal cells from ionizing radiation.
  Example (...)

• vinyl chloride
  12 March 2006

  Vinyl chloride, the monomer from which the polymer polyvinyl chloride is fabricated, was first identified as a carcinogen in animals, but investigations soon disclosed a scattered incidence of the extremely rare hemangiosarcoma of the liver among workers exposed to this chemical.

• azo dyes
  12 March 2006

  The carcinogenicity of most aromatic amines and azo dyes is exerted mainly in the liver, where the "ultimate carcinogen" is formed by the action of the cytochrome P-450 oxygenase systems.
  Thus, fed to rats, acetylaminofluorene and the azo dyes induce hepatocellular carcinomas (but not cancers of the gastrointestinal tract).
  An agent implicated in human cancers, β-naphthylamine, is an exception. In the past, it was responsible for a 50-fold increased incidence of bladder cancer in heavily (...)

• aromatic amines
  12 March 2006

  The carcinogenicity of most aromatic amines and azo dyes is exerted mainly in the liver, where the "ultimate carcinogen" is formed by the action of the cytochrome P-450 oxygenase systems.
  Thus, fed to rats, acetylaminofluorene and the azo dyes induce hepatocellular carcinomas (but not cancers of the gastrointestinal tract).
  An agent implicated in human cancers, β-naphthylamine, is an exception. In the past, it was responsible for a 50-fold increased incidence of bladder cancer in heavily (...)

• polycyclic aromatic hydrocarbons
  12 March 2006

  Polycyclic aromatic hydrocarbons, as benzopyren, represent some of the most potent carcinogens known. They require metabolic activation and can induce tumors in a wide variety of tissues and species.
  Painted on the skin, they cause skin cancers; injected subcutaneously, they induce sarcomas; introduced into a specific organ, they cause cancers locally.
  The polycyclic hydrocarbons are of particular interest as carcinogens because they are produced in the combustion of tobacco, particularly (...)

• carcinogenic agents
  12 March 2006

  A large number of agents cause genetic damage and induce neoplastic transformation of cells. They include (1) chemical carcinogens, (2) radiant energy, and (3) oncogenic viruses and some other microbes.
  Radiant energy and some chemical carcinogens are documented causes of cancer in humans, and the evidence linking certain viruses to human cancers grows ever stronger.
  Each group of agents is considered separately, but several may act in concert or synergize the effects of (...)

• amides
  12 March 2006

  Nitrosamines and amides are carcinogens of interest because of the possibility that they are formed in the gastrointestinal tract of humans and so may contribute to the induction of some forms of cancer, particularly gastric carcinoma.
  Nitrosamines and amides are derived in the stomach from the reaction of nitrostable amines and nitrate used as a preservative, which is converted to nitrites by bacteria. Concerns about these agents have led many to shun processed food containing nitrate (...)

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