The effects of altering time delays of coupled pacing during acute atrial fibrillation

BACKGROUND: Coupled pacing (CP), which consists of delivering a premature electrical stimulation to the heart after the effective refractory period of ventricular activation, is a novel method for controlling ventricular rate during atrial fibrillation (AF). It also has been established that CP improves pump function by enhancing external cardiac work and myocardial efficiency. OBJECTIVE: The purpose of the present study was to determine if two time delays for CP (short and long) would result in similar improvements in ventricular function. METHODS: In a canine model, we applied CP at two time delays (CP-S and CP-L) during two stages: sinus rhythm (SR) and acute AF. The cardiac responses to CP during SR served as the nontachycardic and nondepressed control. During both rhythms, we shortened the coupling interval until we obtained maximal contractility, designated CP-S. Next, we increased the delay until we started to see a measurable secondary contraction (left ventricular pressure development of approximately 20 mmHg). These longer delays were designated CP-L. RESULTS: Our results showed that the ventricular rate of intrinsic activation (VRIA) remained decreased despite prolongation of the time delay of CP during both AF and SR. Also, both delays of CP increased left ventricular systolic pressure (LVSP) and dLVP/dt, which are indices of myocardial contractility. In contrast, CP increased external cardiac work only during AF. Prolonging this time delay did not markedly decrease the improvement in external cardiac work. Myocardial O(2) consumption (MVO(2)) did not significantly change as the result of CP during either SR or AF. Finally, myocardial efficiency improved during AF as the result of CP at both time delays. CONCLUSIONS: In conclusion, shorter time delays for CP increased contractile strength during both SR and AF. However, extending the time delay of CP had minimal effects on diminishing the improved ventricular pump function and energetics that resulted from CP during AF. Thus, the maximal enhancement of myocardial contractility via CP-S was not needed to maintain the improved ventricular function during acute AF when CP is applied.     

Family Stress and Functioning in Children: the Moderating Effects of Children''s Beliefs About Their Control Over Parental Conflict

While factors such as gender and SES have been studied as moderators of stress for children, their perceptions of control have received little attention. In the current study, children's domain-specific perceptions of their control during marital conflict were investigated as potential moderators of the impact of family stress on children's behavior problems, and perceptions of competence. Ninety-four children aged 6-12 years and mothers from families ranging in level of parental conflict from nondiscordant to discordant to physically violent were interviewed. Multiple regression analyses revealed that higher levels of conflict control beliefs acted as compensatory moderators of stress, being associated with lower levels of problem behaviors across stress levels. However, higher conflict control beliefs acted as vulnerability moderators with regard to children's perceptions of competence.     

同济医科大学控烟活动及效果评价

我校自1993年开展控烟工作，1995年9月开始创办无吸烟大学校园，采取了卫生宣教和行政干预等综合措施，并进行了效果评价。高强度干预措施实施前期（1995年3月）和中期（1996年10月）相比，男医学生和男女学生平均吸烟率分别从16.3％和11．4％下降到9．6％和5．94％；男教工和男女教工平均吸烟率分别从28．6％和13．8％下降到13．9％和8．86％。     

The Fort McMurray demonstration project in social marketing: health- and safety-related behaviour among oil sands workers

This is the first round in a series of surveys conducted inFort McMurray as part of the Fort McMurray Demonstration Projectin social marketing. This component of the survey was intendedto focus on the most prominent group of employed workers inthe community and to compare their patterns of response withthe community as a whole. Respondents to the survey were overwhelminglymale (96%), married (72.9%) and living in households of twoto five persons (87.9%). They were predominantly aged 30–44(55%) and graduates of high school (53.5%). Younger male workers(below age 30) were more likely to have a high school diploma(78.3%) or some additional technical or vocational training(21.7% compared to 12.5% overall) and to be unmarried or separated.Attitudes toward safety-related behaviours were stronger thanfor respondents from the community as a whole. Approximately70–100% of all age groups and both sexes showed strongagreement with attitudes involving child car seats and the unacceptabilityof drinking and driving. These attitudes include strong advocacyof vigorous enforcement of occupational health and safety standards.However, they showed a variability similar to the communityas a whole in behaviour at home compared to work, generallyreporting more consistent use of personal protection on thejob than in their own homes, particularly hearing protection.Even so, they were much less likely to perform stretching andwarm-up exercises prior to exertion than community residentsin general. The potential may exist to transfer the technologyand attitudes from workplace health and safety to communitysafety. One possible strategy to accomplish this is to involveworkers in this industry directly in community initiatives.This strategy may be generalizable to any community in whichthere are major employers who place a heavy emphasis on riskcontrol and occupational health and safety.     

Time to contact and the control of manual prehension

In the present study, a kinematic analysis was made of unconstrained, natural prehension movements directed toward an object approaching the observer on a conveyor belt at one of three constant velocities, from one of three different directions (head-on or along the fronto-parallel plane coming either from the subject′s left or right). Subjects were required to grasp the object when it reached a target located 20 cm directly in front of the hand′s start position. The kinematic analysis revealed that both the transport and grasp components of the movement changed in response to the experimental manipulations, but did so in a manner that guaranteed that, for objects approaching from a given direction, hand closure would begin at a constant time prior to object contact (regardless of the object’s approach speed). The kinematic analysis also revealed, however, that the onset of hand closure began earlier with objects approaching from the right than from other directions – an effect which would not be predicted if time to contact was the key variable controlling the onset of hand closure. These results, then, lend only partial support to the theory that temporal coordination between the transport and grasp components of prehension is ensured through their common dependence on time to contact information. Received: 20 September 1996 / Accepted: 16 June 1997     

25例IUD及输卵管结扎与异位妊娠的临床分析

本文对我院收治的异位妊娠84例,其中带环异位妊娠20例,输卵管结扎术后合并异位妊娠5例,以及带环异位妊娠的发生率及其原因、误诊等进行了分析讨论。     

Biomonitoring of aromatic amines and alkylating agents by measuring hemoglobin adducts

Summary Analysis of hemoglobin adducts in blood samples is suitable for the biological monitoring of genotoxic chemicals. The method is specific because the compound to which the individual was exposed is identified. The sensitivity of the method depends on the analytical procedure applied, but is hardly limiting since large amounts of the protein can be obtained. The method provides not only information about the internal exposure to the environmental chemical, but also about the individual's capacity to generate ultimate genotoxic metabolites from it. Since macromolecular damage in blood cells is correlated to that in potential target tissues, this information is relevant to risk assessment, insofar as macromolecular damage produced by a specific chemical can be correlated with the development of tumors.     

便携式野战—Ⅰ型多功能骨科手术器械

一种便携式野战多功能骨科手术器械。重量仅１．１ｋｇ，体积为２１５ｍｍ×１０５ｍｍ×１５ｍｍ，如铅笔盒，而功能多达３３种，具有结构紧凑、操作简便、一械多用、轻巧便携。价廉实用、效价比高的特点。是基层巡诊、抢险救灾救治中适用的骨科器械。     

Laparoscopically assisted gastric surgery using Dexterity Pneumo Sleeve

Background: Laparoscopic surgery has been successfully applied to several gastrointestinal procedures. Although the totally laparoscopic gastrectomy is feasible, tactile sensation and manipulation of the organ as well as the lesion are decreased when compared to open surgery. The Dexterity Pneumo Sleeve is a new device which allows the surgeon to insert a hand into the abdominal cavity while preserving the pneumoperitoneum. This device was used for patients who underwent laparoscopic gastric surgery. Methods: The first patient presented with a non-Hodgkin's lymphoma of the stomach. A laparoscopically assisted distal gastrectomy was performed with Roux-en-Y reconstruction. The second patient had a 5-cm leiomyoma involving the greater curve of the stomach, and this device was used for manipulation of the tumor. The last patient suffered from morbid obesity with its associated medical complications and a ventral hernia. The Sleeve was applied at the hernia site and a laparoscopically assisted gastric bypass was performed. Results: The Pneumo Sleeve was useful in these cases for tactile localization of the tumor and for retraction and manipulation of the stomach and surrounding upper abdominal organs. Conclusions: The utilization of this device resulted in a more easily performed dissection, resection, and anastomosis and was felt to decrease operation time. Received: 18 September 1996/Accepted: 26 December 1996