ABSTRACT
Objective@#We evaluated the effect of low-dose of ionizing radiation on thyroid function of medical occupational group with long-term exposure; furthermore; we analyzed the relationship between the thyroid hormones and the risk factors; such as exposure length; department. Ultimately; providing the scientific basis for setting the ionizing radiation protection standards.@*Methods@#The population who engaged radiodiagnosis and radiotherapy in a tertiary-A hospital were set up as occupational exposure; 724 medical professionals as the research object. We figured out the basic information and general condition of the groups by face-to-face questionnaire survey; By means of the thyroid hormone testing; we analyzed the thyroid hormone levels with different population; occupational exposure factors. Then; obtained the prevalence of thyroid nodules by the thyroid ultrasound. Besides; we used the logistic regression model to analyze the risk factors related to thyroid nodule. Applying Epidata、Excel in data management. All the data was analyzed by statistical software package Stata12.0. Descriptive statistics; single factor analysis of variance and other statistical methods were used for data analysis. Test standard: α=0.05、P<0.05 statistical significant.@*Results@#1. Based on the work experience; we divided the study population into four groups; such as 1-9; 10-19; 20-29; and>30 years. The difference of the TSH level among the four groups was statistically significant (P<0.05) . 2. The multiple logistic regression showed that sex and seniority were the independent risk factors for the abnormal rate of thyroid nodules.@*Conclusion@#Long-term exposure to low-dose ionizing radiatiom could induce the thyroid damage of medical occupational population; which should be broader concerned.
ABSTRACT
AIM To identify potential amino acid residues that contribute to different catalytic characteristics of CYP2A6 and CYP2A13 enzymes in nicotine metabolism. METHODSWild type of CYP2A6 and CYP2A13 and their mutants CYP2A6V117A, CYP2A6G164H, CYP2A6I208S, CYP2A6R372H, CYP2A6S465P and CYP2A13A117V, CYP2A13H164G, CYP2A13S208I, CYP2A13H372A and CYP2A13P465S, were subjected kinetic analysis in nicotine 5'-hydroxylation. RESULTS For CYP2A6, substitution of isoleucine 208 to serine caused dramatic kinetic property changes with K_m and V_( max) varied from 62.25 μmol·L~(-1) and 6.53 mol·min~(-1)·moL~(-1) to 345 μmol·L~(-1) and 2.19 mol·min~(-1)·moL~(-1). However, the corresponding serine 208 to isoleucine mutation did not heavily affect the enzyme activity in CYP2A13. The histidine 372 to arginine mutation resulted in a remarkable catalytic efficiency decrease with K_m and V_( max) changes from 26.01 μmol·L~(-1) and 24.51 mol·min~(-1)·moL~(-1) to 148.7 μmol·L~(-1) and 6.11 mol·min~(-1)·moL~(-1) in CYP2A13, but the switching of argenine 372 to histidine did not show expected corresponding crucial influence in CYP2A6 activity. Substitutions on the other positions changed enzyme activities in different rates. CONCLUSION The isoleucine 208 is crucial to human CYP2A6, while the 372 histidine is a key amino acid residue for CYP2A13 in nicotine 5'-hydroxylation.
ABSTRACT
The present article reviews the advances in the studies of male reproductive toxicity of the pesticides that are widely used and commonly researched in the recent years by means of animal experiment and human investigation. The mechanism of male reproductive toxicity of pesticides is discussed. And problems are raised in the evaluation of human reproductive hazards.