Toxicology adaptive response

Calabrese EJ, Baldwin LA, Mehendale HM. 1993. Contemporary issues in toxicology. G2 subpopulation in rat liver induced into mitosis by low-level exposure to carbon tetrachloride An adaptive response. Toxicol AppI Pharmacol 121 1-7. 

As an adaptive response, the modest overcompensa-tory response is therefore an expected one, rather than an extremely large one (e.g., more than three times the control response). Although this toxicological explanation is consistent with natural selection evolutionary theory, especially with respect to optimal resource... 

Mamett, L. 2002. Oxy radicals, lipid peroxidation and DNA damage. Toxicology 1 1 219-222. Osburn, W. and Kensler, T. 2008. Nrf2 signaling An adaptive response pathway for protection against environmental toxic insults. Mutat. Res. 659 31-39. 

Various mechanisms have been developed by plants to alleviate stress imposed by exposure to toxic metal concentrations. Although the biochemical and molecular bases of adaptation and resistance of plant communities to high metal levels will be discussed extensively in Chapter 3, a survey summarising the possible anti-metal stress defence strategies and mechanisms forms an essential part of this chapter on toxicology. Every plant species, whether it is resistant or not to high metal concentrations, possesses defence responses against increased metal concentrations in the cell indeed. 

In this method, the repeated dose administration with a design similar to toxicology studies is preferred. Studies of up to four weeks duration need to include function tests for hormone secretion (basal concentrations, stimulation or inhibition), and for hormone contents of endocrine organs and tissues (e.g. hypothalamus, pituitary gland, reproductive organs). In the Endocrine Survey, 5 to 7 days of treatment are mandatory because adaptation and response of hormone-dependent organs to the treatment requires that a steady state be reached. Repeated-dose treatment with at least two doses is also needed for a sufficient... 

FIGURE 6.16 Dose-response relationship patterns for different types of teratogen. Adapted from Manson, J.M., Teratogens, in Casarett and DoulF Toxicology, edited by C.D.Klaassen, M.O.Amdur and J.Doull (New York Macmillan), 3rd Edition, 1986. 

FIGURE 6.21 Mechanisms of stimulation of immune responses. From Timbrell, J.A., Introduction to Toxicology. Taylor and Francis, London, 1989. (Adapted from Bowman, W.C. and Rand, M.J. Textbook of Pharmacology, 2nd Edition, Blackwell Scientific Publishers, Oxford). 

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