Study on the establishment and management of GLP in chemical toxicity identification in occupational health institutes / 中国职业医学

@#Abstract: The demand for reliable toxicological data of chemicals runs through every link of occupational health work. The prevention of occupational diseases involves high requirements for the standardization of chemical toxicity assessment in occupational health institutions. Good laboratory practice (GLP) emphasizes the integrity of the test process to trace and supervise the whole process of the test, which is conducive to the standardization of chemical toxicity identification. Therefore, the standardized construction of GLP laboratories is an important starting point for occupational health institutions to carry out chemical toxicity identification. In the construction and management process of GLP laboratories for chemical toxicity identification, occupational health institutions need to build a sound organization and operation system, carry out systematic training and assessment of personnel, establish standard operating norms and emphasize their importance, strengthen the management of facility environment and laboratory, pay attention to quality control and process supervision, and constantly improve their own ability level. To actively adapt to social development and market demand, to provide strong support for occupational health work.

[High expression of LIP1 in Pichia pastoris].

The gene of LIP1, the most important isoenzyme of Candida rugosa lipase (CRL), was artificially synthesized according to its mature peptide sequence. It consisted of 20 codons of preference in Pichia pastoris. The artificial gene was cloned into methanol-inducible expression vector pPICZalphaA, and constitutive expression vector pGAPZalphaA, respectively. The linearized recombinant plasmids were transformed into chromosome of Pichia pastoris SMD1168H strain by electroporation. The abilities of expressing LIP1 in both transformed yeasts had been compared, and the yeast transformed with pGAPZalphaA was more efficient than pPICZalphaA. A recombinant yeast strain named CHT-II expressed LIP1 constitutively, and was the most efficient one. Some enzymatic properties of the recombinant LIP1 were also determined. CHT-II secreted LIP1 into supernate at a level of 2.00x10(5) u/L after 72 h (the cells had been transferred to fresh culture medium at the 24th h). After optimizing the conditions for high cell-density fermentation, the selected yeast strain could secrete LIP1 into supernate at a level of 1.395x10(6) u/L after 72 h. The results indicated that this modification of lip1 gene was successful.

Guinea pig maximization test for trichloroethylene and its metabolites.

OBJECTIVES: To study the contact allergenic activities of trichloroethylene (TCE) and its three metabolites trichloroacetic acid, trichloroethanol and chloral hydrate. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Studies on hypokalemia induced by trimethyltin chloride.

OBJECTIVES: 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. METHODS: 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+. RESULTS: 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). CONCLUSION: 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.