[Protective effects of sevoflurane preconditioning on cerebral ischemia-reperfusion injury in rats].

OBJECTIVE: To investigate if sevoflurane preconditioning attenuate neuronal apoptosis induced by ischemia-reperfusion. METHODS: Thirty-six male SD rats weighing 250 - 300 g were randomly divided into three groups (n = 12 each): control group (group C), ischemia-reperfusion group (group IR) (rats were established cerebral artery clamped and reperfusion model), sevoflurane preconditioning group (group S) (rats were established cerebral artery clamped and reperfusion model after 1 h 2.4% sevoflurane preconditioning). Apoptosis neurons were observed by Hematoxylin and Eosin (HE) staining and transmission electron microscope, TdT mediated Dutp nick end labeling (TUNEL) method was used to count apoptosis neurons density, fresh ischemic brain tissue was taken out, while Caspase-3 zymogen and 20 000 segment were checked by Western blot. RESULTS: apoptosis neurons in group IR were more than ones in group S under HE staining and light microscope and transmission electron microscope, and apoptosis neurons density (cell number/0.1 mm(2)) by TUNEL staining: group C, 13.0 +/- 1.4; group IR, 189.8 +/- 6.8; group S, 110.5 +/- 4.3, the relative gray values of the contents of procaspase-3 and its 20 000 cleavage fragment were 16.72 +/- 3.0, 76.1 +/- 3.4, 51.2 +/- 3.1 and 8.2 +/- 2.3, 59.0 +/- 6.3, 31.2 +/- 5.4 respectively. CONCLUSIONS: Sevoflurane pretreatment can protect neuron on ischemia-reperfusion injury by attenuating neuronal apoptosis in rats.

A titania thin film annular photocatalytic reactor for the degradation of polycyclic aromatic hydrocarbons in dilute water streams.

An external lamp, annular photocatalytic reactor with titania immobilized on a quartz tube was used to degrade two polycyclic aromatic hydrocarbons (PAHs), viz. phenanthrene (PHE) and pyrene (PYR) from a dilute water stream. The thin film geometry was used to obtain both the mass transfer coefficients and intrinsic reaction rate constants for the two compounds on immobilized titania (Degussa P-25) particles. Beyond a feed velocity of 7 cmmin(-1), the conversion was solely reaction rate controlled and was not subjected to mass transfer limitations from the aqueous phase to the immobilized titania film. The overall reaction rate constant was independent of the feed concentration as large as the saturation aqueous solubility of the two compounds. However, the conversion was dependent on the ultraviolet (UV) light illumination intensity at the reactor. The quantum efficiency ranged from 3.7 x 10(-5) to 2.7 x 10(-4) which was somewhat low because of the very low aqueous concentrations of the chemicals. The overall reaction rate constant was 1.6 times larger for pyrene than for phenanthrene. Seven reaction intermediates were identified for the conversion of phenanthrene, while for the degradation of pyrene two intermediates were identified. The presence of the phthalate ester as an intermediate product in the degradation of both PAHs indicates the presence of a quinone in both cases which degrades to the products CO(2) and H(2)O, along with other stable intermediates. Mass balance in a batch reactor showed that only 28.6-40.1% of phenanthrene is mineralized to CO(2) in 1-3h of reaction although 35-67% of the parent compound has disappeared, confirming that a substantial fraction of the parent compound has been converted to stable intermediates that remain in the reactor. A plausible mechanism based on these observations is proposed.