Simulation of time-resolved breast transillumination

A Monte Carlo simulation has been developed to predict the quality of time-resolved images of the breast by transillumination. The smallest diameter of a detectable carcinoma located in the breast has been computed. The simulation suggests that time-resolved imaging of the breast is possible and invaluable in the near infra-red (NIR) by transillumination. The enhancement of the transfer function by the introduction of time-resolved detection is limited by the contribution of noise at short integration times. The estimated diameter of the smallest detectable sphere is derived from the image quality index (IQI) theory and its value is around 4 mm. The simulated images of an absorbing sphere (approximating the carcinoma) within a homogeneous medium (approximating the surrounding tissue) show a significant improvement of the image with short integration time.     

脑梗塞患者治疗时间延误原因及对策

为探讨脑梗塞患者治疗时间的延误原因和对策,对河北、内蒙古部分地区脑梗塞患者治疗时间延误的原因进行了调查分析。共调查了脑梗塞患者１０４８例,在６小时内接受治疗的人数为３２６例,占３１．１１％;在２４小时内,接受治疗的人数为５６６例,占５４．０１％;在２５小时后,接受治疗的人数为４８２例,占４５．９９％。脑梗塞患者治疗延误时间为２３．５５小时,其院前的延误时间为２１．４９小时,占９１．２５％,院后的延误时间为２．０６小时,占８．７５％。调查发现,对脑梗塞患者实施早期治疗,必须在社区内进一步加强脑梗塞症状学和及早诊治意义的科普教育;提高医务人员对脑梗塞诊治水平和治疗紧迫性的认识,建立和完善医院的快速反应系统。只有这样,脑梗塞的早期治疗,才会有根本性的改善     

ARIMA模型在医院卫生消耗材料需求量预测中的应用

目的 阐述ARIMA模型拟合时间序列的方法和步骤,并将其应用于医院卫生消耗材料需求量的预测,为医院设备管理人员提供决策依据。方法 利用SAS软件系统,求解适宜的ARIMA模型,据所得误差评价预测效果。结果 通过对3种卫生消耗材料需求量的预测,相对误差在10％左右,预测效果较为可靠。结论 医院卫生消耗材料需求量的近期预测中引入时间序列的ARIMA模型分析方法,能够对实际工作产生积极的指导意义。     

二硫化碳作业女工早期胚胎损伤的剂量反应关系

目的 探讨女工二硫化碳（ＣＳ２）接触水平与胚胎早期发育障碍之间的剂量－反应关系。方法 前瞻观察生育女工妊娠所需的月 经周期数;收集每个月经周期胚胎植入期尿样,检测绒毛膜促性腺激素含量;监测女工作业地点ＣＳ２浓度。结果 ２５７名接触组经临床确诊妊娠的女工,各月经周期妊娠机率低于３６６名对照组女工,时间妊娠率随女工ＣＳ２接触水平（ＣＳ２接触浓度以ＣＳ２接触工龄）升高而降低：妊娠率＝０．７０３３－０．０     

肺血管磁共振成像:比较二维TOF、三维TOF及Gd-DTPA增强

目的 探讨２种常用的ＭＲ血管成像方法对正常肺动脉图像质量的影响及Ｇｄ－ＤＴＰＡ知其中的作用。材料和方法：用１．０Ｔｅｓｌａ超导ＴＲＩ系统,体线圈技术,随机选择无人心肺疾患志愿者４６例,行２Ｄ ｔｕｒｂｏ ＦＬＡＳＨ和／或３Ｄ ＦＩＳＰ肺部ＭＲＡ检查共１１３次,行Ｇｄ－ＤＴＰＡ增强后２Ｄ ｔｕｒｂｌ ＦＬＡＳＨ和／或３Ｄ ＦＩＳＰ扫描共４７次。计算机测量肺动脉和背景噪声的信号强度,计算出肺动脉的信噪     

香港脑血管病死亡率时间趋势研究

OBJECTIVE: To describe the time trend of mortality rates of cerebrovascular diseases (CVD) in Hong Kong for the period of 1976 to 1995, and to compare them with those in the more developed countries around the world. METHODS: Mortality rates of CVD were standardized directly using world standard population in 1961. Annual percent changes of mortality rates of CVD were estimated with a non-linear regression. Birth-cohort analysis was carried out at an interval of five-year of age to compare their age-specific mortality rates of CVD in different birth cohorts. Time trend of cause-specific mortality rates of CVD both in males and females was fitted with a simple linear regression model. RESULTS: Considerable downward trend of CVD mortality was observed during the past twenty years. Mortality rates among men and women decreased by 50.96% and 37.85% in 1995, as compared to those in 1976, respectively. Although in general, a greater trend in CVD mortality was observed during the last 10 years, as compared with that in the previous 10 years, an annual increase in CVD mortality of 1.34% was found among males aged 35 to 44 years during the latter 10 years. CVD mortality for both males and females decreased steadily by 1% per year. CVD mortality for females will catch up with that for males by the year of 2013, if such a trend continues. Birth-cohort analysis showed that those born more recently at the same age-group had lower mortality of CVD (except for those born after 1955). Data from hospital admission showed that improvement in the treatment for CVD could have contributed partly to the decrease in its mortality. CONCLUSION: Time trend of mortality of CVD in Hong Kong was similar to that in many other economically developed areas around the world.     

Trends in presentation of congenital heart disease in a population-based study in Malta

Differing pathological haemodynamics in cardiac malformations lead to varying modes and timings of presentation. This study identifies historical trends in presentation of congenital heart disease in a population-based study. All patients diagnosed as having congenital heart disease in Malta between 1960–1994 were included (n = 868). Analysis was carried out on trends in referral sources, modes of presentation and birth prevalence. The number of patients diagnosed with congenital heart disease increased over the period under study. For both patients not requiring intervention (n = 283) and those requiring intervention (n=585), the proportion diagnosed prior to hospital discharge increased (p 0.005). There was a decreasing trend for general practitioners to refer cases (p < 0.0001), and an increasing trend for paediatricians to refer such patients (p 0.0003). The commonest presentation to the general practitioner was an incidental finding (92%), while paediatricians referred more patients for cyanosis or heart failure (p 0.005). For lesions not requiring intervention, the commonest lesion referred was ventricular septal defect from all sources. For lesions requiring intervention, the commonest lesion detected prior to hospital discharge was tetralogy of Fallot. Atrial septal defects were the commonest lesions detected after discharge by both paediatricians and general practitioners. An increase in the proportion of hospital diagnoses is attributed to increasing rate of hospital delivery, and greater training and experience in doctors performing neonatal examinations prior to discharge. Patients diagnosed after discharge are increasingly diagnosed by paediatricians due to an increasing pool of paediatricians and better parent awareness and education.     

槲皮素对培养人视网膜色素上皮细胞增生及DNA合成的影响

目的研究槲皮素(quercetin, QUE)对培养人视网膜色素上皮(retinal pigment epithelium, RPE)细胞增生和DNA合成以及对表皮生长因子(epidermal growth factor, EGF)促RPE细胞增生和DNA合成作用的影响。方法用细胞计数和3H-胸腺嘧啶核苷(3H-thymidine, 3H-TdR)掺入方法,观察不同浓度(200、100、50、1μmol/L)的QUE和最大浓度的QUE(200μmol/L)在不同作用时间（24-168小时）,分别单独或与EGF共同作用时,对RPE细胞增生及DNA合成的影响,排除着色的死细胞,用活细胞计数法判断药物的细胞毒性作用。结果QUE 200μmol/L具有最强的抑制效应,48小时时抑制效应已明显出现,96小时时抑制达到高峰。与QUE单独作用相比,QUE对EGF的促RPE细胞增生效应能产生更强的抑制。QUE无细胞毒性作用,各实验组细胞活力均在85.00%以上。结论QUE以剂量依赖和时间依赖的方式抑制RPE细胞的增生,尤其是由EGF刺激的增生,并且对培养的RPE细胞无细胞毒作用。(中华眼底病杂志,1999,15:27-29)     

Time of day effects on sympathoadrenal and pressor reactivity to exercise in healthy men

Summary To investigate the influence of time of day on sympathoadrenal and pressor reactivity during exercise, eight trained men [age, mean (SD), 24 (0.5) years; maximal oxygen uptake ( ), 4.7 l·min^–1] performed bouts of static (ST) and dynamic (DYN) exercise at 0600–0800 hours (AM) and at 1600–1800 hours (PM). The ST protocol utilized a two-leg isometric contraction at 30% maximum voluntary contraction until failure, and was monitored by a strain gauge interfaced from a leg extension apparatus to a computer. Heart rate (f_c) and blood pressure ( ) responses were recorded at rest, after 1 and 2 min of exercise, and at failure. Epinephrine (EPI) and norepinephrine (NE) levels were recorded before exercise, and after 2 min of exercise. The DYN exercise protocol involved stationary. cycling for consecutive 6-min periods at 60% and 80% . f_c, , EPI, and NE were recorded before exercise and at each workload. No differences were observed in preexercise or exercise f_c under any condition. Preexercise did not differ under any condition. The response to DYN was significantly higher at 80% during PM only. was significantly higher in ST-PM at 1 min, 2 min, and failure. Elevations in both systolic and diastolic P _a contributed to this difference. Preexercise EPI-ST-AM was significantly elevated vs PM, but no other preexercise data were significantly different. Absolute exercise levels were significantly higher for EPIST-PM vs AM only, but the percentage change from baseline was significantly (P<0.01) higher in ST-PM for EPI (+231% PM vs + 32% AM) and NE (+352% PM vs +216% AM). The EPI and NE responses to DYN exercise tended to be higher in AM, but were not significantly different. These data support a time of day pattern in sympathoadrenal and pressor reactivity to exercise that is dependent on the type of activity involved but independent of baseline patterns.     

The differential effects of haloperidol and methamphetamine on time estimation in the rat

Forty rats were trained to make a left lever response if a signal (white noise) was 2.5s and to make a right lever response if the signal was 6.3s. When seven intermediate signal durations, to which responses were not reinforced, were randomly interspersed the probability of a right-lever (long) response increased as a function of signal duration. Methamphetamine shifted this psychometric function leftward and decreased its slope: haloperidol also decreased the slope but shifted the function rightward. A combination of haloperidol and methamphetamine led to a function similar to the saline control function. The leftward shift probably reflects an increase in the speed of an internal clock, and the rightward shift probably reflects a decrease in its speed. Since methamphetamine releases several catecholamines, including dopamine, and haloperidol blocks dopamine receptors, it is plausible that the horizontal location of the psychometric function (the speed of the clock) is related to the effective level of dopamine.