用PCR技术产前诊断人巨细胞病毒感染

用ＥＬＩＳＡ法筛选早孕妇女血人巨细胞病毒ＩｇＭ（ＨＣＭＶ－ＩｇＭ），在孕１２￣２０周用聚合酶链式反应（ＰＣＲ）技术检测其羊水中ＨＣＭＶ－ＤＮＡ，对胎儿巨细胞病毒感染作出产前诊断。在３８４例孕妇中，筛选出血ＨＣＭＶ－ＩｇＭ阳性２６例为实验组，其羊水ＨＣＭＶ－ＤＮＡ检出率为３４．６２％；从２５８例ＨＣＭＶ－ＩｇＭ阴性中选出２０例为对照组，其羊水ＨＣＭＶ－ＤＮＡ检出率为１０．０％，两组比较有显著性差异（     

Paracentric inversion of Xq and ovarian dysfunction

We report on a paracentric inversion X(q13 q24) in a 20-year-old woman with ovarian dysfunction. The findings add evidence on the role of breakpoints in Xq13 and Xq24 in causing ovarian dysfunction. A review of the published data on paracentric inversion of chromosome X is included.     

The effects of practice and delay on motor skill learning and retention

The present study assessed the effects of amount of practice and length of delay on the learning and retention of a timed motor sequence task. Participants learned to reproduce ten-element visual sequences by tapping in synchrony with the stimulus. Participants were randomly assigned to a varied-practice condition or a varied-delay condition. In the varied-practice condition, participants received either one, three, or six blocks of practice followed by a fixed 4-week delayed-recall. In the varied-delay condition, participants received three blocks of practice followed by a varied delay of either 3 days, or 2, 4, or 8 weeks. Learning was assessed by changes in accuracy, response variance, and percent response asynchrony. Our results showed that amount of practice per se did not affect learning and retention of the task. Rather, distribution of practice over several days was the most important factor affecting learning and retention. We hypothesize that passage of time is essential for a maximum benefit of practice to be gained, as the time delay may allow for consolidation of learning, possibly reflecting plastic changes in motor cortical representations of the skill. With regards to delay, our findings suggest that explicit and motoric components of a motor sequence are likely to be learned and maintained in separate but interacting systems. First, only the longest delay group showed decrements in percent correct, indicating that longer lengths of delay might hinder retrieval of explicit aspects of the task. Second, all groups showed a decrement in percent response asynchrony, suggesting that synchronization may be a more difficult parameter to maintain because it relies heavily on sensorimotor integration.     

Tooth loss and retention: analysis on 500 maxillae of a multitribal group of Bantu-speaking South African blacks

This study analyzes tooth loss and retention in 500 dry maxillae of adult South African Bantu-speaking blacks. The tribe, sex, and stated age at death were available. Specimens were equally distributed over the third to the seventh decades of life. The presence of dental units was recorded and analyzed between and within age groups. A total of 5063 dental units was recorded. Reduction of the frequency of dental units was mild and not significant between the third and fourth decades of life and between the sixth and seventh. Severe and significant tooth loss was recorded between the fourth and the fifth, and between the fifth and the sixth decades of life. Specimens from younger individuals (from 21 to 30 years of age) retained more teeth in the anterior region; after the third decade of life, there was a clear and significant persistence of canines with tendency toward loss of teeth anterior and posterior to them. Based upon the present observations and previous studies in this population, it is suggested that: (a) in most teeth, tooth retention pattern is indirectly related to periodontal bone loss (In the canines, however, the long roots rather than "resistance" to periodontitis may be the cause for the relatively high longevity rate); and (b) caries may have been the main cause for tooth loss until the fourth decade of life--later, periodontal disease may have become the predominant reason.     

Timing of Diosgenin Appearance in Suspension Cultures of Dioscorea deltoidea

Cycloheximide and compactin were added to cell suspension cultures of DIOSCOREA DELTOIDEA. Cycloheximide inhibited growth and diosgenin biosynthesis completely at 40 mg/l when added during the growth phase. Compactin partially inhibited growth and diosgenin production at 100 microg/l when added during the growth phase. [1- (14)C]-Acetate incorporation into diosgenin was about 20-fold higher when added during the early stages of growth as compared to addition in the stationary phase. Incorporation of [1- (14)C]-acetate into diosgenin was inhibited by compactin only during the early stages of growth. These results indicate the formation of an accumulating intermediary metabolite during the early stages of growth which is transformed into diosgenin when D. DELTOIDEA cells are in the stationary phase.