title: Enhancement and attenuation of cytogenetic damage by vitamin C in cultured human lymphocytes exposed to thiotepa or L-ethionine.
abstract: Vitamin C (vit C) at 2 mM enhanced sister chromatid exchange (SCE) frequencies induced by Thiotepa (THIO) or L-ethionine (L-ETH) in cultured human lymphocytes. However, when vit C was tested at 0.02 mM and 0.2 mM a rather protective effect on SCE rates induced by THIO or L-ETH was identified. Vit C (2 mM) caused a cell division delay in cultures treated with THIO or L-ETH. Division delays caused by THIO or L-ETH were reversed in the presence of 0.02 mM or 0.2 mM vit C. Mitotic indices (MIs) in cultures treated with THIO or L-ETH continued to be suppressed in the presence of 2 mM vit C. However, vit C at 0.02 mM reversed suppression of MIs caused by L-ETH or THIO. These findings illustrate the complexity of the interactions of vit C in biological systems and indicate that with different concentrations vit C can cause or prevent genetic toxicity.
mesh_terms: D001205:Ascorbic Acid / Q000494:pharmacology*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D005001:Ethionine / Q000037:antagonists & inhibitors / Q000633:toxicity*; D006801:Humans; D008214:Lymphocytes / Q000187:drug effects* / Q000648:ultrastructure; D012854:Sister Chromatid Exchange / Q000187:drug effects*; D013852:Thiotepa / Q000037:antagonists & inhibitors / Q000633:toxicity*
chemical_list: D013852:Thiotepa; D001205:Ascorbic Acid; D005001:Ethionine