Effect of <Emphasis Type="SmallCaps">l</Emphasis>-Thyroxine on Micronuclei Frequency in Peripheral Blood Lymphocytes in Clinical and Experimental Conditions

The aim was to study the genotoxic effect of high concentration of thyroxine (T₄) in vivo in peripheral blood lymphocytes (PBL) of the patients suffering from thyroid disorders. The effect was compared by performing in vitro experiments with addition of increasing concentration of T₄ (0.125–1 µM) in whole blood samples from healthy donors. Cytokinesis-blocked micronuclei (CBMN) assay method was used to assess the DNA damage in the PBL. The study included 104 patients which were grouped as control (n = 49), hyperthyroid (n = 31) and hypothyroid (n = 24). A significant increase in micronuclei (MN) frequency was observed in hyperthyroid patients when compared with the hypothyroid and euthyroid group thereby suggesting increased genotoxicity in hyperthyroidism (p < 0.001). A significant increase in MN frequency was observed at T₄ concentration of 0.5 µM and above when compared to lower T₄ concentrations (0.125 and 0.25 µM) and basal in in vitro experiments (p = 0.000). The results indicate that the T₄ in normal concentration does not exhibit the genotoxic effect, as observed in both the in vivo and in vitro experiments. The toxicity of T₄ increases at and above 0.5 μM concentration in vitro. Therefore acute T₄ overdose should be handled promptly and effectively so as to avoid the possible genotoxic effect of high concentration of T₄ in vivo.     

Effects of flaxseed<Emphasis Type="Italic">(Linum usitatissimum) chutney</Emphasis> on gamma-glutamyl transpeptidase and micronuclei profile in azoxymethane treated rats

Antioxidant property of flaxseed chutney was evident by decreasing lipid peroxidation (TBARS) and predictor enzyme γ-glutamyl transpeptidase profile and micronuclei formation in azoxymethane treated rats. After 10 weeks, rats fed with either fiber-free basal diet or Antioxidant diet exhibited over sevenfold increase in γ-glutamyl transpeptidase activity and nearly fourfold increase in micronuclei load in comparison to controls (p<0.001). A significant reduction in both γ-glutamyl transpeptidase level (52%) and micronuclei formation (47%) was observed in fiber-free basal diet/Antioxidant diet/flaxseed chutney diet fed rats. Relative to rats fed fiber-free basal diet, the profile of γ-glutamyl transpeptidase and micronuclei load was not significantly altered.