Block copolyesters of L-lactide and ε-caprolactone were synthesized by melt copolymerization of ε-caprolactone and L-lactide.The degradation performance of copolyesters was investigated by quartz crystal microbalanc...Block copolyesters of L-lactide and ε-caprolactone were synthesized by melt copolymerization of ε-caprolactone and L-lactide.The degradation performance of copolyesters was investigated by quartz crystal microbalance with dissipation(QCM-D).Diisocyanate terminated copolyesters could obtain via the reaction of copolyesters and diisocyanate.Diisocyanate terminated copolyesters could react with polyol resin to prepare degradable polyurethane which can be used in antifouling coatings.In this paper,we also discussed the degradation products release action and antifouling performance of the copolyesters film.展开更多
Epidemiological surveys and animal experiments have shown that 2-bromopropane induces oligozoospermia in exposed workers and inhibits spermatogensis in laborratory animals. However, themechanism by which 2-bromopropan...Epidemiological surveys and animal experiments have shown that 2-bromopropane induces oligozoospermia in exposed workers and inhibits spermatogensis in laborratory animals. However, themechanism by which 2-bromopropane exerts its effects is unknown. To this end, we examined the formation of testosterone by the Leydig cells and their survival of these cells in the Presence of differ-ent concentrations of 2-bromopropane in vitro. Leydig cells were isolated following vascular Perfu-sion, enzymatic dissociation and Percoll gradient centrifugation techniques. The cells were cultured in culture dishes. After 8 h, different cultures were exposed to 2-bromopropane at concentrations of 0.01 mmol/L, 0.10 mmol/L and 1.00 mmol/L. In order to stimulate Leydig cells to secrete testos-terone, human chorionic gonadotropin (hCG) was also added. Cell viability was determined using the trypan blue dye exclusion test and cell numbers were counted by hemocytometer. Testosterone secretion was detected by radioimmunoassay. The cell viability decreased after exposure to 2-bromo-propane in a dose-dependent way, but no morphological change was observed. The cell number de-creased in the 2-bromopropane-treated cultures. The secretion of testosterone did not manifest de -tectable changes in the culture treated with 0.10 mmol/L and 0.01 mmol/L of 2-bromopropane;however, it decreased significantly (P < 0. 02) in the Presence of 1.00 mmol/L. Therefore, ourresults strongly suggest that 2-bromopropane may exert its cytotoxic effects on heydig cells in vitro.We speculate that the decrease in the numbers of Leydig cells caused by 2-bromopropane was medi-ated by a feedback mechanism resulting from a lower testosterone concentration.展开更多
Both female and male Wistar rats were divided into 3 groups according to their body weights. The two test groups were given 75 μg/ml and 7.5 μg/ml HgCl2 respectively, via drinking water, while the control group was ...Both female and male Wistar rats were divided into 3 groups according to their body weights. The two test groups were given 75 μg/ml and 7.5 μg/ml HgCl2 respectively, via drinking water, while the control group was given distilled water. Animals were mated after the male rats were treated for 12 weeks and female rats for 2 weeks. Blood samples from rats were taken on the 18th day of the pregnancy and the results showed that the HgCl2 was absorbed and stored in the blood in the form of inorganic mercury. The greatest amount of HgCl2 was found in the kidney. The placenta and the testis also had high mercury deposits. Fetuses showed low levels of HgCl2, thus, the placenta appears to serve as a barrier against HgCl2. No pathological changes were observed in the placenta, ovary,liver, and kidney in the female rats, but the epithelial cells of the renal proximal convoluted tubules were cloudy and swelling. The renal corpuscle showed no changes in the male rats. Pathological examination showed that a portion of the seminiferous epithelia were falling off, and the number of sperm released by the male rats was reduced.Examination by electron microscopy revealed that particulate fat was increased in sperm cells, which suggests that spermatozoa had been degenerated and were possibly one of the causes for the decreased rates of pregnancy in the exposed groups. No malformation of organs and bones in the rat fetuses were observed展开更多
文摘Block copolyesters of L-lactide and ε-caprolactone were synthesized by melt copolymerization of ε-caprolactone and L-lactide.The degradation performance of copolyesters was investigated by quartz crystal microbalance with dissipation(QCM-D).Diisocyanate terminated copolyesters could obtain via the reaction of copolyesters and diisocyanate.Diisocyanate terminated copolyesters could react with polyol resin to prepare degradable polyurethane which can be used in antifouling coatings.In this paper,we also discussed the degradation products release action and antifouling performance of the copolyesters film.
文摘Epidemiological surveys and animal experiments have shown that 2-bromopropane induces oligozoospermia in exposed workers and inhibits spermatogensis in laborratory animals. However, themechanism by which 2-bromopropane exerts its effects is unknown. To this end, we examined the formation of testosterone by the Leydig cells and their survival of these cells in the Presence of differ-ent concentrations of 2-bromopropane in vitro. Leydig cells were isolated following vascular Perfu-sion, enzymatic dissociation and Percoll gradient centrifugation techniques. The cells were cultured in culture dishes. After 8 h, different cultures were exposed to 2-bromopropane at concentrations of 0.01 mmol/L, 0.10 mmol/L and 1.00 mmol/L. In order to stimulate Leydig cells to secrete testos-terone, human chorionic gonadotropin (hCG) was also added. Cell viability was determined using the trypan blue dye exclusion test and cell numbers were counted by hemocytometer. Testosterone secretion was detected by radioimmunoassay. The cell viability decreased after exposure to 2-bromo-propane in a dose-dependent way, but no morphological change was observed. The cell number de-creased in the 2-bromopropane-treated cultures. The secretion of testosterone did not manifest de -tectable changes in the culture treated with 0.10 mmol/L and 0.01 mmol/L of 2-bromopropane;however, it decreased significantly (P < 0. 02) in the Presence of 1.00 mmol/L. Therefore, ourresults strongly suggest that 2-bromopropane may exert its cytotoxic effects on heydig cells in vitro.We speculate that the decrease in the numbers of Leydig cells caused by 2-bromopropane was medi-ated by a feedback mechanism resulting from a lower testosterone concentration.
文摘Both female and male Wistar rats were divided into 3 groups according to their body weights. The two test groups were given 75 μg/ml and 7.5 μg/ml HgCl2 respectively, via drinking water, while the control group was given distilled water. Animals were mated after the male rats were treated for 12 weeks and female rats for 2 weeks. Blood samples from rats were taken on the 18th day of the pregnancy and the results showed that the HgCl2 was absorbed and stored in the blood in the form of inorganic mercury. The greatest amount of HgCl2 was found in the kidney. The placenta and the testis also had high mercury deposits. Fetuses showed low levels of HgCl2, thus, the placenta appears to serve as a barrier against HgCl2. No pathological changes were observed in the placenta, ovary,liver, and kidney in the female rats, but the epithelial cells of the renal proximal convoluted tubules were cloudy and swelling. The renal corpuscle showed no changes in the male rats. Pathological examination showed that a portion of the seminiferous epithelia were falling off, and the number of sperm released by the male rats was reduced.Examination by electron microscopy revealed that particulate fat was increased in sperm cells, which suggests that spermatozoa had been degenerated and were possibly one of the causes for the decreased rates of pregnancy in the exposed groups. No malformation of organs and bones in the rat fetuses were observed
