二氧化硫体内衍生物对雄性小鼠精子的毒性效应

为了探讨二氧化硫(SO2)的雄性生殖毒理效应,研究了SO2体内代谢衍生物———亚硫酸钠(Na2SO3)和亚硫酸氢钠(NaHSO3)混合液(物质的量比为3:1)对雄性昆明小鼠精子的毒性作用.采用腹腔注射(i.p.)染毒方法,每天注射一次,连续5 d,于染毒后d 35处死动物,观察和分析小鼠的精子活动度、数量和畸形率.结果表明:(1)SO2衍生物可引起小鼠精子数量尤其是正常活动度精子数量减少,引起不活动精子数量增加,且呈剂量-效应关系;(2)SO2衍生物可引起多种类型的精子畸形增加,尤其可引起不定形畸变精子的频率显著增加,总精子畸变率随染毒剂量的增加而呈剂量依赖性增高.由此推论,SO2污染有一定的雄性生殖毒性.图1表2参14     

试论煤矿井下快速断电安全技术

论述了煤矿井下漏电保护和短路保护装置的现状和实施快速断电安全技术的必要性;介绍了煤矿快速断电安全技术的发展水平;对快速断电安全技术中的几个问题进行了探讨;提出了可行的缩短故障取样时间技术方案     

Window Sensitivity Functions for Line Transect Sampling

L and width 2w, then by a selection of viewing window is meant a choice of w, with the intent being to search for optimal viewing windows, with the goal in mind of improving variances of estimators of population density, reducing sampling effort, while maintaining the property of unbiasedness. The notions of increasing window sensitivity (IWS) and decreasing window sensitivity (DWS) are introduced, and a method of deriving confidence intervals is discussed.     

WEBGIS及其在环境管理上的应用

WebGIS是当前地理信息系统发展的一个重要方向,本文介绍了采用了Java技术和XML技术的新的WebGIS体系结构,并结合ArcIMS的定制开发,结合通化市污染物总量控制给出了吉林省环境保护行业的WebGIS应用系统开发实例.     

Complications of cordocentesis in high-risk pregnancies: Effects on fetal loss or preterm delivery

Between 1990 and 1993, 166 cases underwent cordocentesis and were followed for at least the following 4 weeks in the Prenatal Diagnosis and Therapy Centre of Vienna University. The indications for the procedure were structural malformations in 46·4 per cent of the cases, other high-risk diagnoses in 48·8 per cent, and maternal age over 35 years in only 4·8 per cent. We investigated retrospectively all cases of complications resulting in fetal loss or preterm labour. Abortion, intrauterine fetal death, chorioamnionitis, and preterm delivery occurred in 0·6, 5·4, 0·6 and 9·0 per cent of these cases, respectively, adding up to a total of 26 cases (15·7 per cent). Although this rate looks relatively high, 20 of the 26 cases had already displayed signs implying a complicated prognosis. Neither maternal age, gestational age, number of attempts, nor placental location correlated with fetal loss or preterm delivery. Significantly higher rates of fetal loss or preterm delivery were observed when cordocentesis was performed in cases diagnosed as duodenal/intestinal stenosis or hydrops–ascites–hydrothroax/hygroma colli (P=0·0488 and P=0·0005). The frequency of complications did not decrease as the experience of the operators increased.     

Mark-recapture estimators for dual frame population size of prominent nesting structures: the effect of uncertain detection probability

The combined mark-recapture and line transect sampling methodology proposed by Alpizar-Jara and Pollock [Journal of Environmental and Ecological Statistics, 3(4), 311–327, 1996; In Marine Mammal Survey and Assessment Methods Symposium. G.W. Garner, S.C. Amstrup, J.L. Laake, B.F.J. Manly, L.L. McDonald, and D.C. Robertson (Eds.), A.A. Balkema, Rotterdam, Netherlands, pp. 99–114, 1999] is used to illustrate the estimation of population size for populations with prominent nesting structures (i.e., bald eagle nests). In the context of a bald eagle population, the number of nests in a list frame corresponds to a pre-marked sample of nests, and an area frame corresponds to a set of transect strips that could be regularly monitored. Unlike previous methods based on dual frame methodology using the screening estimator [Haines and Pollock (Journal of Environmental and Ecological Statistics, 5, 245–256, 1998a; Survey Methodology, 24(1), 79–88, 1998b)], we no longer need to assume that the area frame is complete (i.e., all the nests in the sampled sites do not need to be seen). One may use line transect sampling to estimate the probability of detection in a sampled area. Combining information from list and area frames provides more efficient estimators than those obtained by using data from only one frame. We derive an estimator for detection probability and generalize the screening estimator. A simulation study is carried out to compare the performance of the Chapman modification of the Lincoln–Petersen estimator to the screening estimator. Simulation results show that although the Chapman estimator is generally less precise than the screening estimator, the latter can be severely biased in presence of uncertain detection. The screening estimator outperforms the Chapman estimator in terms of mean squared error when detection probability is near 1 wheareas the Chapman estimator outperforms the screening estimator when detection probability is lower than a certain threshold value depending on particular scenarios.     

Randomized clinical trial of transabdominal versus transcervical chorionic villus sampling methods

The relative advantages and disadvantages of transabdominal (TA) and transcervical (TC) chorionic villus sampling (CVS) in terms of fetal risks and efficacy were evaluated in a clinical trial conducted on 1194 women randomized at 7–12 weeks' gestation. The results of the study indicate that, if any, the relative risk of fetal loss following either procedure is less than double that of the alternative technique when performed by a skilled operator. Overall, the fetal loss rate (spontaneous abortions following randomization, terminations of pregnancy, and perinatal deaths) is 16.5 and 15.5 per cent, respectively, among women allocated to TA- and TC-CVS. The two procedures are equally effective, although TA-CVS is associated with a significantly lower rate of repeat device insertions; on the other hand, a higher weight of chorionic tissue is obtained, on average, with TC-CVS. Bleeding is more common following TC-CVS, while peritoneal reaction developed only after TA-CVS. No diagnostic problems specifically related to one sampling technique were identified.     

Prenatal diagnosis in advanced maternal age. Amniocentesis or CVS,a patient's choice or lack of information?

Ninety-six women of advanced maternal age were interviewed about the way they obtained information on prenatal diagnosis and about how the decision was made as to what procedure was to be performed (transabdominal chorionic villus sampling (TA-CVS) or amnio-centesis). In the CVS group, women visited their physician or midwife earlier in pregnancy (mean 7.1 weeks) than those in the amniocentesis group (mean 10.7 weeks). The availability of prenatal diagnosis was not mentioned during the first antenatal visit in 55 per cent of women from the amniocentesis group as opposed to 25 per cent from the TA-CVS group. Approximately 40 per cent of women eligible for prenatal diagnosis did not receive any information from the referring body prior to counselling at our centre. Only 29 per cent of women who underwent amniocentesis had actually chosen this procedure; 71 per cent were too late to undergo TA-CVS at 12 weeks. It is concluded that information to the patient must be improved in order to ensure early referral for prenatal diagnosis.     

First trimester chorionic villus sampling versus mid-trimester genetic amniocentesis-preliminary results of a controlled prospective trial

This controlled prospective study assesses the relative risks of first trimester chorionic villus sampling (CVS) versus mid-trimester gentic amniocentesis (GA). CVS subjects and amnio-centesis controls were comparable with regard to several confounding variables which might influence the risk of pregnancy loss including maternal age, smoking, alcohol consumption, gestational age at study entry, and history of vaginal bleeding or poor prior reproductive outcome. The most common indication for prenatal diagnosis was advanced maternal age (n = 511). In this subgroup, spontaneous abortion (<24 weeks) occurred in 2·9 per cent of CVS subjects versus 4−3 per cent of amniocentesis controls. The sum of spontaneous and therapeutic abortions (<24 weeks) was identical (5·3 per cent) in both groups. Therefore, intervention in the CVS group (i.e., therapeutic abortion for cytogenetic abnormalities) did not influence the observed risk of pregnancy loss. Overall perinatal mortality rates were also similar in both groups. No significant differences were identified for a number of pregnancy outcome parameters including 5 min Apgar score, birth weight, body length, head circumference, gestational age at delivery, preterm delivery, fetal growth retardation, congenital malformations, and neonatal complications. Preliminary results of this controlled prospective study suggest that chorionic villus sampling carries a low and acceptable risk.