ABSTRACT
Objective To study the reasons of natural death of Oncomelania hupensis snails by comparing the differences of the indicator days covered with water DCW in snail marshland and non?snail marshland around the build of Three Gorges Dam in Eastern Dongting Lake areas. Methods Two marshlands were selected one was a non?snail marshland Qianliang Lake and another was a snail marshland Junshan Park . The measuring points were set through the mechanical sampling. The snails and elevation of the points were surveyed and the data of the water levels from the hydrological station were collected and then DCWs were calculated. Results From 1995 to 2013 DCWs of the marshland of natural death of snails were all more than that of the snail marshland P<0.01 . In Qianliang Lake marshland the difference between DCW before natural death and DCW from natural death until the dam was not significant P=0.23 while DCWs of the two stages both were more than that after the dam P1=0.045 P2=0.002 . Before the build of the dam DCW of the Qianliang Lake marshland of natural death of snails was more than that after the build of the dam P=0.013 and there was the same situation in Junshan Park marshland P=0.005 . The relationship between snail density and DCW was not significant in Junshan Park marshland rs=0.008 P=0.914 and the reference range of DCW of all the measuring points was 76-251 days. Conclusion In the eastern Dongting Lake district the build of Three Gorges Dam and DCW may be not the direct factors affecting the natural death of snails and the latter may change the distribution of snails.
ABSTRACT
Free clodronate has a very poor ability to permeate cell membrane and an extremely short half-life in circulation. However, it can be encapsulated with liposomes, and then can be phagocytosed by monocytes/macrophages. Clodronate is released in the cells and be metabolized to a toxic ATP analog. By this way, monocytes/macrophages can be effectively depleted. The study showed that the prepared liposomes had a negative charge (-40mV) on the surface and a high encapsulation efficiency of clodronate (17.6%～19.0%) with an average size of 200nm. The spherical shape of liposome was confirmed both by transmission electron microscope and laser scanning confocal microscope. Neither free clodronate nor liposome clodronate inhibited vascular endothelial cell and smooth muscle cell proliferation. Clodronate, once encapsulated in liposomes, significantly reduced macrophage proliferation in a dose dependent manner, while free clodronate or empty liposomes had no effect on macrophages. With laser scanning confocal microscope observation, rhodamine labeled liposomes were found to penetrate and accumulate inside monocytes and macrophages, but not into the smooth muscle cells. Furthermore, rhodamine labeled liposomes without encapsulating clodronate was found to accumulate inside macrophages, but causing no damage to cells. The macrophages which engulfed rhodamine labeled clodronate liposomes would manifest a morphological structure resembling apoptotic state. The results suggest that monocytes/macrophages can be depleted via phagocytosis of liposome encapsulated clodronate without affecting non-phagocytotic cells.