RESUMO
Objective To investigate the toxicity of alpha terthienyl to the larvae of Aedes albopictus , its influencing factors and effect on the larva deve lopment. Methods Under experimental ultraviolet A (UVA),the number of dead,pupal or eclosive mosquito larvae was determined on the condition of different doses of alpha terthienyl and different disposal time in the dark;the number of dead larvae was also determined under sunlight on the condition of different doses of alpha terthienyl and different disposal time to water. Results The LC 50 of alpha terthienyl to Aedes albopictus larvae was 2.37 ?g/L under UVA. The best effect was shown when the larvae were incubated with alpha terthienyl 3 h in dark. Alpha terthienyl could significantly inhibit the larva deve lopment and the emergence of the pupae. Under strong sunlight, the larvae were quickly killed by high concentration alpha terthienyl. The 24 hours effect of alpha terthienyl was better when it was applied at 5 AM than that of at 10 AM and 1PM. Conclusion Alpha terthienyl is an effective, practicable larvicide which prohibits the growth and development of the larvae of Aedes albopictus .
RESUMO
Objective To explore possible mechanisms of hepatic fibrosis by investigating the ultrastructural dynamic changes of liver tissue, especially several kinds of cells related to hepatic fibrosis.. Methods. Murine schistosomal hepatic fibrosis model was established by infecting mice with Schistosoma japonicum cercariae. Routine transmission electron microscopy was used to observe the liver tissue. H.E. staining was used for examining the pathological changes. . Results . H.E. staining showed that the model was established successfully. Ultrastructural observation showed that at the 6th week after infection, the necrosis of hepatocytes around the acute granulomas occurred; the number of sinusoidal endothelial fenestrae and vitamin A droplets in fat-storing cells decreased; large phagosomes and rough endoplasmic reticulum could be seen in the cytoplasm of Kupffer′s cells. At the 8th week, steatosis was found in some hepatocytes, some microvilli emerged on a few inter-hepatocytic surfaces and the inter-hepatocytic spaces were enlarged. Large collagen fibrillar bundles filled in the perisinusoidal spaces, and capillarization of hepatic sinusoids was observed. Secretory vesicles filled with collagen fibrils appeared in the cytoplasm of fat-storing cells with large amount of collagenous fiber bundles surround the cells. Rough endoplasmic reticulum increased in Kupffer′s cells. At the 10th week, fat-storing cells were activated and transformed into myofibroblasts. At the 12th week, the number of myofibroblasts decreased but that of fibroblasts and fiber cells increased. . Conclusion . Activation of fat-storing cells and transformation from fat-storing cells into myofibroblasts are the critical link in the development of hepatic fibrogenesis following schistosome infection. Kupffer′s cells, necrotic hepatocytes and sinusoidal endothelial cells may relate to the activation of fat-storing cells. Capillarization of hepatic sinusoids possibly accelerates the development of hepatic fibrosis.