Inhibitory mechanisms of three compounds for chrysotile-induced biological activities / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To study the effects of aluminum citrate (AC), rare earth compounds (REC) and sodium selenite (SS) on the surface elements of chrysotile fibers and the inhibitory mechanisms of three compounds for chrysotile-induced biological activities.</p><p><b>METHODS</b>After being soaked in 250, 500 and 1000 microg/ml aluminum citrate solutions, 125, 250, 500 and 1000 microg/ml mixed rare earths solutions or 125, 250, 500 and 1000 microg/ml sodium selenite solutions for 10 min or 1 hour, the fabrication and the levels of surface elements of chrysotile fibers were determined.</p><p><b>RESULTS</b>Aluminum citrate, mixed rare earths or sodium selenite all could be adsorbed by chrysotile fibers. After pretreatment of chrysotile fibers with aluminum citrate, mixed rare earths or sodium selenite solutions for 10 min or 1 hour, the corresponding elements or ion on the surface of chrysotile fibers increased with the increase of concentration of the solutions.</p><p><b>CONCLUSION</b>Pretreatment of chrysotile with aluminum citrate, mixed rare earths or sodium selenite solutions can change the fabrication and the levels of surface elements of chrysotile fibers, and inhibit the biological activities of chrysotile by "sealing" some "active sites" on the surface of chrysotile fibers.</p>

Effects of exposure to asbestos on plasma activity of glutathione S-transferases / 中华预防医学杂志

<p><b>OBJECTIVE</b>To understand the effects of exposure to asbestos and GSTM1 genotypes on plasma activity of glutathione S-transferases (GSTs).</p><p><b>METHODS</b>Ninety-four workers exposed to asbestos and 51 controls were selected, and their general information, occupational history and personal behavior were collected by questionnaire. Venous blood specimen was collected from each of them and plasma was separated for detection of GSTs activity and lymphocytes for DNA extraction and GSTM1 genotyping.</p><p><b>RESULTS</b>Plasma activity of GSTs in the asbestos-exposed workers (23.0 +/- 6.9) U/L was significantly lower than that in the controls (32.6 +/- 11.8) U/L, which declined with the length of employment in asbestos industry and the increase of cumulated dose of asbestos. Stratification of workers by GSTM1 genotypes showed that plasma activity of GSTs in asbestos-exposed workers with GSTM1+/+ or GSTM1-/- were (24.0 +/- 6.1) and (22.5 +/- 7.3) U/L, respectively, lower than those in the controls with the same genotypes (38.1 +/- 13.2) and (26.8 +/- 6.6) U/L. Plasma activity of GSTs in the control workers with GSTM-/- was significantly lower than in those with GSTM+/+, and, so did in asbestos-exposed workers, but without statistically significant difference.</p><p><b>CONCLUSION</b>Exposure to asbestos could significantly decrease plasma activity of GSTs, and GSTM1 genotypes could affect on the activity of GSTs in the control workers, which was not so obvious in asbestos-exposed workers.</p>

Effects of chrysotile asbestos on the activities of cytochrome P4501A1 and glutathione S-transferase in A549 cell line / 中华预防医学杂志

<p><b>OBJECTIVE</b>To study the effects of chrysotile on the activities of some enzymes for xenobiotics metabolism.</p><p><b>METHODS</b>UICC chrysotile (UC) and China Mangya chrysotile (MC) asbestos fibers were used at different doses (0, 25, 50, 100, 200 mg/L) to study its effects on the activities of cytochrome P4501A1 and glutathione S-transferase (GST) in A549 cell line. Also, the effects of chrysotile on the activities of CYP1A1 and GST induced by benzo(a)pyrene were studied.</p><p><b>RESULTS</b>The activity of EROD increased slowly with the increasing dose of UC, as A549 cells were incubated with UC for 24 h, and EROD activity increased by 40% at a dose of 200 mg/L UC. However, activity of EROD decreased by 32% with 48 h incubation at the same dose, indicating that lower dose of UC and short time could induce the activity of EROD in A549 cells, whereas higher doses and long time could inhibit its activity. MC exhibited a multiphasic effects on the activity of EROD, whether at a dose of 25 mg/L for 24 h or 48 h all gave the strongest induction, 1.86 times or 1.28 times as controls, respectively. However, EROD activity decreased with the increases in MC doses and incubation time, with the lowest as 35% of the controls. The effect of UC on GST activity was not so obvious, with the highest as the increase in its activity by 20%. The highest induction of MC to GST activity was at a dose of 25 mg/L, 2, 5 times as that in controls. With the increases in its doses, effects of MC on GTS activity became inhibition from induction, like that on EROD activity. MC at a dose of 200 mg/L could lower the activity of GST by 18.7%. A549 cells were incubated with chrysotile fiber for 24 h firstly, and then incubated with benzo(a)pyrene to induce the activities of EROD and GST. The results showed that neither UC nor MC could affect the activity of EROD induced by benzo(a)pyrene. However, UC at a dose of 200 mg/L and MC at 100 mg/L could increase the activity of GST induced by benzo(a)pyrene.</p><p><b>CONCLUSION</b>Chrysotile at different doses or its different types showed varied effects on the activities of EROD and GST in A549 cell lines, probably because of different physicochemical characteristics and surface activity of two kinds of asbestos.</p>