Chemical toxicants, cellular response

ER function, as can external agents such as calcium ionophores and chemical toxicants (Rao, et al., 2001) which can cause ER stress. ER responds to stress by triggering a specific signalling pathway termed the unfolded protein response (UPR). The UPR serves to protect the cell from normal variations that occur in the cellular environment (Ma, et al., 2004, Rao, et al., 2001). Recent evidence suggests that the UPR can also be activated in tumours (Ma, et al., 2004). 

Toxicity of biomaterials is usually viewed at both cellular and systemic levels. Toxicity at the cellular level, also known as cytotoxicity, is often caused by direct chemical toxicity of biomaterials, inflammatory reactions, or immune responses to biomaterials. Excessive or severe cytotoxicity, inflammatory reactions, or immune responses may lead to the toxicity remote from the initial insult and affecting organs or organ systems, which is defined as systemic toxicity. It is important to emphasize that toxicity caused by biomaterials is usually dose dependent. For cytotoxicity or nonimmune systemic toxicity, a threshold below which the biomaterial reveals little toxicity may be carefully determined by in vitro and in vivo studies. However, for immune systemic toxicity, determination of such a threshold is extremely difficult because immune responses are individual-dependent and largely affected by properties, dosage, and implantation location of the biomaterials. Toxicity of nanomaterials will be further discussed in this chapter. 

C I Cellular response of chemical toxicants occurs through both structural and metabolic mechanisms in dte cell. 

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