Objective To explore the effects of hypoxia on expression of signal transduction and activators of transcription (STAT3) gene and proliferation of rat pulmonary arterial smooth muscle cells (PASMCs). Methods RT PCR and western blot were used to assess the levels of STAT3 mRNA and tyrosine phosphorylated STAT3 protein after primarily cultured rat PASMCs were exposed to hypoxia for 2h, 6h, 12h, 24h respectively. 3 H TdR incorporation was used to observe the cell proliferation. Results The expression of STAT3 mRNA was increased after exposure of PASMCs to hypoxia for 2h, and peaked when exposed for 6h, then declined when exposed for 12h, but still higher than that in PASMCs when exposed to normal oxygentension. The level of tyrosine phosphorylated STAT3 was increased when exposed for 6h,peaked after 12h and delined after 24h in PASMCs exposed to hypoxia. With prolongation of time of hypoxia, 3 H TdR incorporation in PASMCs was significantly higher, and reached a maximum after 24h. Conclusion The results suggested that hypoxia could induce the expression of STAT3 mRNA and activation of STAT3 protein in PASMCs, implying that STAT3 gene might play an important role in the early stage of hypoxia induced PASMCs proliferation

A kinetic method for the detemination of trace rhodium based on the catalytic effect of Rh on the oxidative color reaction of diantipyry1-(p-dimethylamino)-phenylmethane (DAMAM) with potassium periodate in the H3PO4 medium and ot wateer bath was estabished. The optimum condition and kinetic parameters of this reaction were studied in detail. The linear range of the determination was 0～80μg/L, and the detection limit was 6.20×10-7g/L. The apparent activation energy og catalytic reaction was found to be 89.03kJ/mol, rate constant was 2.51×10-4/s. The system wasstable at least 6h. The method has been applid to determine trace rhodium in some catalyst samples with the relative standard deviation of 2.7%～3.2%(n=6) and recovery of 98.2%～103.2% (n=5).

The catalytic effect of ruthenium on the oxidation reacti on of methylene blue (MB) was investigated and applied for the determination of ruthenium(Ⅲ) by the kinetic spectrophotometry in the sulfuric acid medium at 90±0.5℃. The optimum reaction conditions, kinetic parameters and r eaction mechan ism were studied. The linear ranges for the determination of ruthenium (Ⅲ) were 0.0～1.2 and 1.2～5.6 μg/L with a detection limit of 0.05 μg/L . Almost no foreign ions more than 50-fold concentration of Ru(Ⅲ) I nterfered with the determination. The method, which was of high sensitivity, good selectivity and stability, was s uccessfully applied for the determination of trace ruthenium in some ores and m e tallurgical products, the RSD (n=8) was 1.3%～2．2％ and the recovery was between 99% and 105%.