effects of different environmental conditions on the stability of the immuno-reactive triiodothyronine [T3], thyroxine [T4] and thyrotropin [TSH] in human sera

It is frequently obligatory to expose samples for hormonal assay to different environmental and other processing factors. On the other hand, it is mandatory to identify border-line cases and avoid false results of thyroid dysfunction. These different environmental factors are focused on in this work. Endogenous T3, T4 and TSH were measured by the most convenient ELISA technique in human sera samples exposed to different temperature gradients for different periods. Aliquots of different samples were also exposed to freezing thawing cycles, delayed separation and hemolysis. T3, T4 and TSH assay showed nonsignificant difference in their concentrations when stored for up to 7 days in the refrigerator [4C] and at room temperature. The same results were reported for samples stored frozen at 20C for up to one month. Surprisingly, the 3 hormones were stable also after 5 cycles freezing and thawing, apparent hemolysis and delayed separation for up to 8 hours. These data clarify the degree of stability of the hormones responsible for the diagnosis of thyroid disorders

Relationship between selenium and lipid hydroperoxide formation in human atherosclerosis

In this study, serum lipid hydroperoxides, selenium, HDL-cholesterol, total cholesterol as well as triglycerides [TC] were determined. The levels of total cholesterol and TG were increased in contrast to low HDL-cholesterol in atherosclerotics compared to the control group. The serum levels of lipid hydroperoxides were significantly in creased in atherosclerotics [126.68 + 13.9 ng/ml] compared to the control group [50.5+4.37 ng/ml]. Serum selenium shows no significant difference between atherosclertics [230 + 22 ng/ml] and the control group [200 +/- 11 ng/ml]. It is apparent that, although serum lipid hydroperoxides play a well established role in the pathogenesis of atherosclerosis, yet selenium alone-has no protective role against atherosclerosis. So, all antioxidants including selenium must be studied as a whole to verify their role in atherogenesis