In recent years, the incidence of placenta previa has been increasing. According to the literature, it is mainly related to induced labor, artificial abortion, cesarean section, high aging pregnancy, multipara or smok...In recent years, the incidence of placenta previa has been increasing. According to the literature, it is mainly related to induced labor, artificial abortion, cesarean section, high aging pregnancy, multipara or smoking. The placenta previa is the chief cause of bleeding in late pregnancy and threatens the lives of mother and infant, resulting in a high risk problem in obstetrics. This article studies 322 cases of placenta previa from my hospital and Dalian Obstetrics and Gynecological Hospital from January, 2002 to July, 2009, on the basis of clinicretrospective analysis, in order to deepen our understanding and art of treating placenta previa. The study revealed that: 1. With 322 cases of placenta previa, the incidence was 0.73%. It was higher than the incidence 0.3% reported abroad and lower than the incidence 0.94% reported in our country. The data were from sampling survey and did not prove relations between placenta previa and ages, different from the result obtained abroad in which placenta previa had relation with pregnancy ages. The outcome needs further study. But artificial abortion, induced labor, cesarean section and multipara clearly influence the incidence. The study did not analyze the relation between smoking and placenta previa, but there was external data proving that smoking was related to placenta previa; 2. Ultrasound-B is a better method for examination at present; 3. In cases of vaginal childbirth there was a higher incidence of lateral placenta previa and partial placenta previa. The conservative temporization and timely cesarean section can greatly decrease the mortality of mother and infant.展开更多
The chiral separation of phenylsuccinic acid(PSA)was studied by reversed phase high-performance liquid chromatography(RP-HPLC)with cyclodextrins(CDs)as chiral mobile phase additives.The effects of types of CDs,concent...The chiral separation of phenylsuccinic acid(PSA)was studied by reversed phase high-performance liquid chromatography(RP-HPLC)with cyclodextrins(CDs)as chiral mobile phase additives.The effects of types of CDs,concentration of hydroxypropyl-β-cyclodextrin(HP-β-CD),percentage of organic modifier,pH value and column temperature on enantioselective separation were investigated.The quantification property of the developed RP-HPLC method was examined.The chiral recognition mechanism of PSA was also discussed.The results show that a baseline separation of PSA enantiomers is achieved on a Lichrospher C18 column(4.6 mm(inner diameter)×250 mm,5μm)with HP-β-CD as chiral mobile phase additive.The capacity factors of R-PSA and S-PSA are 3.94 and 4.80,respectively.The separation factor and resolution are respectively 1.22 and 8.03.The mobile phase is a mixture of acetonitrile and deionized water(20-80,volume ratio)containing 10 mmol/L HP-β-CD and 0.05% trifluoroacetic acid(pH 2.5,adjusted with triethylamine)with a flow rate of 1.0 mL/min.The ultraviolet(UV)detector is set at 254 nm.The likely roles are inclusion interaction,induction and hydrogen bonding between HP-β-CD and PSA enantiomers.展开更多
文摘In recent years, the incidence of placenta previa has been increasing. According to the literature, it is mainly related to induced labor, artificial abortion, cesarean section, high aging pregnancy, multipara or smoking. The placenta previa is the chief cause of bleeding in late pregnancy and threatens the lives of mother and infant, resulting in a high risk problem in obstetrics. This article studies 322 cases of placenta previa from my hospital and Dalian Obstetrics and Gynecological Hospital from January, 2002 to July, 2009, on the basis of clinicretrospective analysis, in order to deepen our understanding and art of treating placenta previa. The study revealed that: 1. With 322 cases of placenta previa, the incidence was 0.73%. It was higher than the incidence 0.3% reported abroad and lower than the incidence 0.94% reported in our country. The data were from sampling survey and did not prove relations between placenta previa and ages, different from the result obtained abroad in which placenta previa had relation with pregnancy ages. The outcome needs further study. But artificial abortion, induced labor, cesarean section and multipara clearly influence the incidence. The study did not analyze the relation between smoking and placenta previa, but there was external data proving that smoking was related to placenta previa; 2. Ultrasound-B is a better method for examination at present; 3. In cases of vaginal childbirth there was a higher incidence of lateral placenta previa and partial placenta previa. The conservative temporization and timely cesarean section can greatly decrease the mortality of mother and infant.
基金Project(20776038)supported by the National Natural Science Foundation of China
文摘The chiral separation of phenylsuccinic acid(PSA)was studied by reversed phase high-performance liquid chromatography(RP-HPLC)with cyclodextrins(CDs)as chiral mobile phase additives.The effects of types of CDs,concentration of hydroxypropyl-β-cyclodextrin(HP-β-CD),percentage of organic modifier,pH value and column temperature on enantioselective separation were investigated.The quantification property of the developed RP-HPLC method was examined.The chiral recognition mechanism of PSA was also discussed.The results show that a baseline separation of PSA enantiomers is achieved on a Lichrospher C18 column(4.6 mm(inner diameter)×250 mm,5μm)with HP-β-CD as chiral mobile phase additive.The capacity factors of R-PSA and S-PSA are 3.94 and 4.80,respectively.The separation factor and resolution are respectively 1.22 and 8.03.The mobile phase is a mixture of acetonitrile and deionized water(20-80,volume ratio)containing 10 mmol/L HP-β-CD and 0.05% trifluoroacetic acid(pH 2.5,adjusted with triethylamine)with a flow rate of 1.0 mL/min.The ultraviolet(UV)detector is set at 254 nm.The likely roles are inclusion interaction,induction and hydrogen bonding between HP-β-CD and PSA enantiomers.
