Urinary S-phenylmercapturic acid variation in benzene exposed / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To observe the urinary S-phenylmercapturic acid (S-PMA) variation in the benzene dynamic exposed rat models and benzene exposed workers, and study the feasibility of use of urinary S-PMA as the biomarker in benzene exposed.</p><p><b>METHODS</b>In an animal model study, forty-eight adult Wistar rats were randomly divided into 4 groups: the control group, low-dose group, middle-dose group and high-dose group. The exposed groups were dynamically exposed for 28 days (4 periods) by benzene and the concentration was monitored. The urine was immediately collected after every exposure period and detected by the liquid chromatographic/mass spectrometry methods. In a cohort study, eighty benzene exposed workers in a ship-yard in Guangzhou were selected as the exposed subjects while forty healthy officers in the same shipyard who were not occupationally exposed to benzene were treated as the control. The urine was collected after work shift. The urinary S-PMA and the benzene in the workplace was treated as the rat model.</p><p><b>RESULTS</b>In the animal model study, the urinary S-PMA increased along with the environment benzene in every period and had significantly difference in the different exposed groups (P < 0.01 or P < 0.05), but did not change along with the exposed time course (P > 0.05). In the cohort study, the urinary S-PMA in the high-dose group [(27.2 +/- 7.9)microg/L] was significantly higher than the low-dose group [(13.6 +/- 3.4)microg/L] (P < 0.01). Otherwise, the background of urinary S-PMA was lower than 5microg/L in both workers and rat models.</p><p><b>CONCLUSION</b>The urinary S-PMA can be proposed as a sensitive biomarker of occupational benzene exposure.</p>

HLA-DM polymorphism and risk of trichloroethylene induced medicamentosa-like dermatitis / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To establish the association between genetic polymorphisms of HLA-DMA and HLA-DMB and risk of developing trichloroethylene-induced medicamentosa-like dermatitis (TIMLD).</p><p><b>METHODS</b>Sixty-one cases were medically confirmed to have been affected with TIMLD and 60 controls were selected from exposed workers who were free from TIMLD. The TIMLD cases and controls were similar in terms of age, sex, and duration of exposure. DNA was extracted both from the TIMLD cases and controls, HLA-DMA and HLA-DMB loci were amplified by using Touchdown PCR, and the alleles and genotypes were confirmed by restriction fragment length polymorphism (RFLP) and direct sequencing. Finally, the frequencies of HLA-DMA and HLA-DMB variants were compared between the two groups.</p><p><b>RESULTS</b>The results showed that the frequency of HLA-DMA*0101 and HLA-DMB*0103 alleles was significantly increased in TIMLD patients than in controls (71.3% vs. 55.0% for HLA-DMA*0101; P<0.05) (11.5% vs. 3.3% for HLA-DMB*0103; P<0.05). In addition, the frequency of HLA-DMA*0102-*0102 homozygous genotype was also significantly higher in the controls than in the patients (25.0% vs. 8.2%, P<0.05), whereas the frequency of heterozygous HLA-DMB *0101-*0102 genotype was lower in the patients in comparison with the controls. Conclusion The polymorphisms of HLA-DM may be associated with the susceptibility to TIMLD.</p>

Studies on hypokalemia induced by trimethyltin chloride / 生物医学与环境科学（英文）

<p><b>OBJECTIVES</b>To determine the possible relationship between plasma potassium concentration and severity of acute trimethyltin chloride (TMT) poisoning and to assess the mechanism of TMT induced hypokalemia.</p><p><b>METHODS</b>SD rats were treated with various dosages of TMT (i.p.). All the indices were measured and analysed for determining their possible relations with plasma K+.</p><p><b>RESULTS</b>With increase of dosage, the plasma K+ level dropped rapidly, and deaths appeared more quickly. The LD50 of TMT (i.p.) was 14.7 mg/kgbw. In the low dosage group (10 mg/kgbw), the plasma K+ level dropped slowly with the lowest dosage on day 6 (4.85 mmol/L). It rose again on day 11 (5.06 mmol/L), and recovered on day 28. The poisoning signs corresponded with decline of the span of K+ level. The plasma Na+ level dropped half an hour after TMT treatment, but recovered 24 h later. In the high dosage group (46.4 mg/kgbw), the levels of plasma K+ and Na+ fell rapidly within half an hour (P < 0.05), the intracellular potassium concentration of RBC did not decrease obviously (P > 0.05), the activities of Na(+)-K(+)-ATPase and Mg(2+)-ATPase in RBC membrane were depressed remarkably (P < 0.01, P < 0.05, respectively), the plasma aldosterone concentrations rose as high as tenfold (P < 0.01), the arterial blood pH fell from 7.434 to 7.258 (P < 0.01), pCO2 was raised from 29.62 to 45.33 mmHg (P < 0.01). In the 24 h urine test, when rats were treated with TMT (21.5 mg/kgbw, i.p.), urine volume, urinary potassium, sodium and chloride increased significantly in comparison with those in the controls (P < 0.01).</p><p><b>CONCLUSION</b>TMT could induce hypokalemia in SD rats. The available evidence suggests that TMT can induce acute renal leakage of potassium. At the same time, a significant rise of plasma aldosterone may play an important role in promoting potassium leakage from kidney to result in severe hypokalemia with inhaling acid-base abnormalities produced, which aggravate the poisoning symptoms. In the end the rats would die of respiratory failure.</p>

Guinea pig maximization test for trichloroethylene and its metabolites / 生物医学与环境科学（英文）

<p><b>OBJECTIVES</b>To study the contact allergenic activities of trichloroethylene (TCE) and its three metabolites trichloroacetic acid, trichloroethanol and chloral hydrate.</p><p><b>METHODS</b>A modified guinea pig maximization test (GPMT) was adopted. The skin sensitization (edema and erythema) was observed in trichloroethylene, trichloroacetic acid, trichloroethanol, chloral hydrate and 2,4-dinitrochlorobenzene.</p><p><b>RESULTS</b>The allergenic rate of TCE, trichloroacetic acid and 2,4-dinitrochlorobenzene was 71.4%, 58.3% and 100.0% respectively, and that of trichloroethanol and chloral hydrate was 0%. The mean response score of TCE, trichloroacetic acid and 2,4-dinitrochlorobenzene was 2.3, 1.1, 6.0 respectively. The histopathological analysis also showed an induction of allergenic transformation in guinea pig skin by both TCE and trichloroacetic acid.</p><p><b>CONCLUSION</b>TCE appears to be a strong allergen while trichloroacetic acid a moderate one. On the other hand, both trichloroethanol and chloral hydrate are weak sensitization potentials. Immunologic reaction induced by TCE might be postulated as the pathological process of this illness. Consequently, it is suggested that in the mechanism of Occupational Dermatitis Medicamentose-Like (ODML) induced by TCE, the chemical itself might be the main cause of allergy. As one of its metabolic products, trichloroacetic acid might be a subordinate factor.</p>