The decline in US teen pregnancy rates, 1990-1995

OBJECTIVES: Estimate pregnancy, abortion, and birth rates for 1990 to 1995 for all teens, sexually experienced teens, and sexually active teens. DESISN: Retrospective analysis of national data on pregnancies, abortions, and births. Participants. US women aged 15 to 19 years. OUTCOME MEASURES: Annual pregnancy, abortion, and birth rates for 1990 to 1995 for women aged 15 to 19 years, with and without adjustments for sexual experience (ever had intercourse), and sexual activity (had intercourse within last 3 months). RESULTS: Approximately 40% of women aged 15 to 19 years were sexually active in 1995. Teen pregnancy rates were constant from 1990 to 1991. From 1991 to 1995, the annual pregnancy rate for women aged 15 to 19 years decreased by 13% to 83.6 per 1000. The percentage of teen pregnancies that ended in induced abortions decreased yearly; thus, the abortion rate decreased more than the birth rate (21% vs 9%). From 1988 to 1995, the proportion of sexually experienced teens decreased nonsignificantly. CONCLUSIONS: After a 9% rise from 1985 to 1990, teen pregnancy rates reached a turning point in 1991 and are now declining. Physicians should counsel their adolescent patients about responsible sexual behavior, including abstinence and proper use of regular and emergency contraception.     

Autonomic response to auditory stimulation

Autonomic and behavioral response to fear stimulation (sudden noise 80 dB) was studied in 12 sleeping infants at ages 8–50 weeks. The aim of the present study was to identify a possible passive defense response in infants. The response, which is widespread in birds and mammals, is characterized by apnea and bradycardia with circulatory changes as seen during the forced diving response. Upon stimulation, two respiratory responses were elicited: apnea preceded by irregular respiration or simple irregular respiration. Apnea was elicited in 58% of stimulations at ages 8–16 weeks compared to 14% at 28–50 weeks. The mean duration of apnea decreased from 7.8 s(± 1.8 s) at 8–13 weeks to 4.7s (± 1.1s) at 17–20 weeks. The preceding irregular respiration increased from 5.3 s (± 4.4 s) to 10.6 s (± 5.4 s) at the same ages. The heart rate response was biphasic and were interpreted as the orienting response. The mean deceleration in relation to apnea was 16% at 8–16 weeks and was reduced to 8% at 28–50 weeks. Infants of smoking mothers were more prone to respond with apnea than infants of nonsmoking mothers (73% versus 38%). REM sleep and long postprandial sleep time increased the probability of apnea response (62% versus 38% and 66% versus 35%). The responses seen may be interpreted as expressions of the passive defense response.     

关附甲素的结构简化物及抗心律失常活性

为寻找活性高、毒副作用小的抗心律失常新药,以关附甲素为先导物进行结构简化,共设计合成了1-苯基-3-烷胺基-1,2-丙二醇类化合物14个和吲哚嗪类化合物9个。对抗氯仿诱发小鼠心律失常试验表明,Ⅰ₁,Ⅰ₂,Ⅰ₃,Ⅰ₇,Ⅰ₈,Ⅰ₁₄和Ⅱ27个化合物有较显著的抗心律失常活性,其中Ⅰ₂,Ⅰ₃,Ⅰ₇和Ⅰ₈抗心律失常活性优于关附甲素。     

抗组胺药敏感性的细胞色素P-450在不同年龄组大鼠肝脏微粒体中的测定

抗组胺药敏感性细胞色素P-450(简称HP-450)主要存在于肝脏微粒体,是一个有组胺H₁受体和细胞色素P-450(CytP-450)两种物质特性的蛋白质,我们利用[³H]mepyramine为同位素标记进行受体配体结合实验,检测HP-450随着大鼠增龄而致的动力学特征,同时又从酶学比较Cytp-450在不同年龄组大鼠肝脏微粒体内的变化规律和趋势,发现HP-450和CytP-450都明显地随着大鼠年龄而变化,其中HP-450的Bmax值和Kd值在大鼠出生后2至8周内增加最快,8至10周达到最高水平并趋向稳定状态,CytP-450也有同样的趋势,并且HP-450的增长与CytP-450的增长幅度具有良好的相关性(相关系数r=0.625)。实验中未曾发现性别间的差异。     

The efficacy of bismuth subsalicylate in the treatment of acute diarrhoea and the prevention of persistent diarrhoea

A controlled, randomized, double-blind study in Bangladeshi children (ages 4-36 mo) with acute diarrhoea was undertaken to determine whether bismuth subsalicylate (BSS) would prevent the development of persistent diarrhoea (PD) in young children. The children were randomized to two groups: 226 were given liquid oral BSS, (as Pepto-Bismol), 100 mg/kg/d for 5 d; 225 were given placebo of identical appearance. On admission to the study, the two groups were comparable both clinically and microbiologically. Rotavirus was found in 56% of all the children, and enterotoxigenic E. coli in 31% of a subsample studied. Children treated with BSS had less severe and less prolonged illness than those treated with placebo (p = 0.057). There was, however, no difference in the development of PD between the two groups (8% and 11%). Unexpectedly, patients treated with BSS gained significantly more weight (2.3%) than those treated with placebo (0.5%; p < 0.001) during the course of the study. No toxicity of BSS was detected. Conclusion: Treatment with BSS had a modest therapeutic effect on acute diarrhoea, as has been previously demonstrated, but with no suggestion of a therapeutic effect on the prevention of persistent diarrhoea in this group of patients.     

tdic(9;12): a nonrandom chromosome abnormality in childhood B-cell precursor acute lymphoblastic leukemia: a Pediatric Oncology Group Study

In a review of 432 children with newly diagnosed acute lymphoblastic leukemia (ALL), we identified a new nonrandom translocation, tdic(9;12)(p1?1;p1?2), in the leukemic marrow cells of eight patients. Seven had hypodiploid karyotypes that lacked chromosomes 9 and 12 and contained a der(12), tdic(9;12); the eighth had a pseudodiploid karyotype with two normal 9 chromosomes, one normal 12 and the der(12), tdic(9;12). Abnormalities involving chromosomes other than 9 and 12 were noted in four of the eight patients. All cells with the tdic(9;12) expressed both the common ALL antigen and HLA-DR. Cytoplasmic immunoglobulin, a marker of pre-B ALL, was detected in one case with the tdic(9;12) but was absent in the other seven. Our results suggest that the tdic(9;12)(p1?1;p1?2) rearrangement is specifically associated with leukemic B cell precursors.