心肌细胞跨缝隙连结兴奋传播的若干问题

连续并行求解大量心肌细胞的动作电位方程以及计算第一相邻细胞对之间的跨缝隙连结兴奋的传导是心脏电生理模型的运行方式，故跨缝隙连结兴奋传导的仿真是建模与仿真中的主要问题之一。本文提出了我们在构造一个全心脏电生理模型所涉及的跨缝隙连结兴奋传导仿真的有关问题，介绍了解决的方法，并讨论了这些方法的副作用 。     

人体左心室复合材料有限元机械模型的建立

人体心脏通过电兴奋引起的心肌收缩实现泵血功能，而心肌的力学特性高度依赖于肌纤维旋向。根据肌纤维结构和复合材料理论建立了人体左心室的三维有限元机械模型，并讨论了心电兴奋力及后负荷的计算问题，最后仿真研究了在正常心脏兴奋传播过程中左心室在载荷作用下的力学响应，并与磁标记的MR成像结果及其他有关模型进行了比较。研究结果表明该模型可用于探讨心脏的机械功能和生理病理机制，为建立具有电生理及力学性能的虚拟心脏奠定了基础。     

基于电生理-力学复合心脏模型的右心室三维运动分析

在原有电生理心脏模型基础上,我们采用有限元方法和复合材料理论建立了一个电生理-力学复合双心室模型,并基于该模型对右心室心壁在收缩期的三维运动进行仿真分析。模型建立过程中,考虑了心肌的纤维旋向、心电兴奋产生的心肌收缩力。心室壁位移、最小主应变(E 3)等用来表征心室的运动。仿真结果与加标记磁共振成像的实验结果基本一致。另外,仿真结果还表明,虽然心基部位移最大,但最大收缩力却发生在心尖部,这个结果用一般的动物实验或人体实验是难以得到的。因此,电生理-力学复合双心室模型对于今后进一步评价心脏功能具有重要意义。     

一种自动检测心脏电兴奋时间的新方法

在研究心脏活动的过程中,人工确定心脏的电兴奋时间是一个非常费时困难的工作。这严重防碍了心脏电兴奋事件在心脏手术和心脏电生理试验中的实时应用。本文在以前偶极方法和单极方法基础上,提出了一种新的检测方法。这种方法在确定心脏电兴奋时间时,同时使用偶极信号和单极信号,实验表明这种方法确定的心脏电兴奋时间较为准确。     

心肌电特性参数对心律影响的定量仿真研究

心电场是由心肌的电活动产生的。心肌细胞的电特性及心肌细胞间的传导关系决定了体表电位的分布及心电图的变化。心肌电特性参数主要包括动作电位、兴奋传导速度、不应期及心肌细胞受激时间间隔与动作电位持续时间的关系（间隔－时间关系）等。由于很难通过实验方法来人为改变这些参数，因而临床上有关心肌细胞电特性参数对心律影响的定量知识相当缺乏。本文采用真实三维躯干模型及心脏模型，对心肌电特性参数与心律变化的关系进行定量仿真研究。结果表明，动作电位的持续时间与Ｓ－Ｔ间隔有关；动作电位分布与Ｔ波形状有关；兴奋传导速度决定了整个心电图的变化，而局部普通心肌的传导速度在相当范围内变化似乎对心电图影响不明显，但传导速度超过一定范围后可能产生突变；心肌不应期的变化对心律也有影响，当某心肌单元不应期延长到一定程度后甚至可能引起折返；另外，心肌细胞受刺激时间间隔的长短对动作电位持续时间产生影响，从而影响到心电图的变化     

心脏建模仿真研究进展

本综述了近年来国际上在不同层次上心脏建模仿真的研究成果和进展，分别介绍了亚细胞和细胞层次、组织和器官层次上的心脏电生理模型、机械力学模型和生物化学模型。最后，简要地分析了心脏建模存在的问题并展望了心脏建模仿真领域今后的发展趋势。     

全心脏电生理模型的仿真应用

实现了用细胞自动机式并行计算构造全心脏的电生理模型，并介绍这种电生理模型的仿真设施与应用。仿真应用首先是求解心电图正问题，尤其是仿真各种心律失常心电图，准确说明各种不规则波形所蕴含的电生理意义。其次，是在通道层次对心电活动动力学性质特别是对心律失常形成与维持的机制进行研究，第三，是模拟对心电活动的各种调制与干预，研究起搏，除颤，消融，通道阻滞剂对心电活动的作用。     

一种基于解剖的高分辨心脏电活动模型

提出了一种基于解剖数据的具有真实形状的高分辨心脏电活动模型，它不仅是一个自兴奋模型，而且在模型分辨率方面得到了更大的改善。同时，采用了改进的兴奋传播算法，避免了精度的损失。此外，在计算电流偶极矩时，考虑了所有相邻单元的贡献，使得模型更符合实际情况，精度得到进一步提高，所得结果与电生理实验数据基本吻合。     

味觉电生理建模和仿真的研究进展

味质的结构和化学多样性决定了味觉有基于不同味觉物质的多种传导机制。近年来，随着分子生物学、细胞电生理研究方法的发展，有关味觉受体细胞电生理特性、味觉传导机制及味觉编码的研究取得了很大进展。综述了目前国际上味觉受体细胞电生理特性及其建模仿真方法的研究进展，同时评述目前味觉电生理建模仿真的几种主要方法的特点，最后论述了建模仿真方法对味觉机理以及味觉临床病理学研究的重要意义。     

临床心脏内电生理检查

临床心脏电生理是研究、诊断和治疗心律失常的重要手段,它包括心脏内电生理、食道心脏电生理、程序电刺激、心脏内膜与心脏外膜标测。心脏内电生理是以腔内希氏束电图为主的临床心脏电生理,除描记体表心电图外,还同步记录心腔内不同部位的电位图,包括希氏束电图,必要时给心脏以特定的电刺激,观察心脏内诸电位图的变化,以了解心脏的传导顺序,传导速度及心律失常,它是一项操作复杂的有创性检查方法,必须严格掌握适应症,并由技术熟练、经验丰富的医师从事该项工作。     

Secular change in menarche in women in Madrid

The age at menarche was estimated by recollection in 1617 women between the ages of 18 and 60 in Madrid and a nearby suburb, Pinto. The population of Pinto is working-class and the Madrid group, taken from residential neighbourhoods , belongs to the upper middle class. In both groups we found a diminution in average age at menarche, from 14.04 to 13.02 years in Madrid and from 14.55 to 13.16 years from about 1935 to about 1965 in Pinto. These changes have been more intense in the group which is less well-off economically, where living conditions have varied much more drastically.     

Intestinal helminthiasis in school children in Haiti in 2002

A survey on intestinal helminths in school children was conducted in Haiti in 2002. This first nationwide study involving the entire country was stratified by department according to urban and rural zones using the cluster method. Focusing on elementary school children (n=5792; age range 3 to 20 years), it involved 26 urban and 49 rural schools randomly selected. Stools were preserved in formalin and examined by the Ritchie technique. Thirty-four per cent of stools (1981/5792) tested positive for intestinal helminths with the following parasites identified: Ascaris lumbricoides (27.3%), Trichuris trichiura (7.3%), Necator americanus (3.8%), Hymenolepsis nana (2%), Taenia sp. (0.3%) and Strongyloides stercoralis (0.2%). The helminth prevalence was higher in rural (38.4%) compared to urban areas (30%). There was no significant difference in prevalence by sex and age. The importance of geohelminths changed from one department to another with the highest prevalence found in the Southern department of Grande Anse (73.7%) and the lowest prevalence in the Center department (20.6%). Five out of the country's nine departments had a similar prevalence varying from 25.5% to 28.2%. Intestinal helminthic polyparasitism was observed in a percentage of infested school children comprise between 3.4% and 28.6% according in relation to the geographical area. A program to fight against geohelminths in school children should be initiated as a public health priority. Albendazole is the drug of choice. Frequency of drug distribution should be based on the prevalence of geohelminths in each department.     

Experience in adult population in dengue outbreak in Delhi

A dengue outbreak has recently hit the Indian capital. We studied the clinical profile of adult patients. Five hundred and sixty patients of dengue infection were admitted in a specially created ward according to the criteria laid down by WHO. Haematemesis (28.28%), epistaxis (26.78%) and malena (14.28%) were some of the common presentations. Similarly lymphadenopathy, especially cervical (30.89%), palatal rashes (26.96%) and hepatomegaly (23.75%) were the most commonly encountered findings on physical examination. Most of the cases were of dengue fever with haemorrhage and only 2.5% cases were classified under dengue haemorrhagic fever or dengue shock syndrome. The average hospital stay was 3.4 days but only 9.8 hours in the eleven patients who died, suggesting their late arrival in preterminal situation giving little time for resuscitation. Thrombocytopenia was not a feature and only 12.85% patients had platelet count less than 70,000/cmm. Most of the patients who were admitted with thrombocytopenia, showed normalization in their platelet counts in next few days. Serological examination demonstrated evidence of recent dengue infection in 41.17% patients. Few patients required blood or platelet concentrate transfusion. Eleven patients died, three due to DIC, one of intracranial haemorrhage and seven due to massive gastric haemorrhage. Rest of the patients recovered completely. Thus we can conclude that recent outbreak in Delhi was of dengue fever with haemorrhage and mortality was very low in patients who came early to the hospital.     

Changes in the hypothalamic nuclei in in experimental allergy

Summary In rabbits subjected to prolonged sensitization and in which the Arthus phenomenon was induced there was a marked reaction of the hypothalamic nuclei. Staining by Gomori's method indicated a cellular swelling, loss of granules, and protoplasmic vacuolization in the supraoptic nucleus. There was a considerable increase in the size of the cross-sectional area of the cells. The same effects were much less well shown in the paraventricular nucleus. These results show that marked signs of increased neurosecretion developed in the animals at the height of the Arthus phenomenon.(Presented by Active Member AMN SSSR V. V. Parin) Translated from Byulleten Éksperimental'noi biologii i Meditsiny, Vol. 55, No. 4, pp. 110–113, April, 1963.     

Development in in vitro toxicology

There are three principal pressures driving the development of in vitro toxicology: (1) the need for more efficient testing systems to cope with the large number of xenobiotics currently being developed; (2) public pressure to reduce animal experimentation; and (3) a need for a better understanding of the mechanisms of toxicity. Within this, in vitro toxicology is focused on local, systemic, and target-organ toxicity. It is becoming increasingly apparent that a step or decision-tree approach using input of a variety of experimental data (physicochemical properties, biokinetics, cytotoxicity) provides the most efficient system for predicting toxicity. Examples of the use of in vitro toxicity systems for prediction of systemic toxicity and target-organ (liver) toxicity are presented.Originally presented at ECCP 93.