Peroxisome biogenesis occurs in late dorsal-anterior structures in the development of Xenopus laevis.

Metabolism and development are two important processes not often examined in the same context. The focus of the present study is the expression of specific peroxisomal genes, the subsequent biogenesis of peroxisomes, and their potential role in the metabolism associated with the development of Xenopus laevis embryos. The temporal and expression patterns of six peroxisomal genes (PEX5, ACO, PEX19, PMP70, PEX16, and catalase) were elucidated using RT-PCR. Functionally related peroxisomal genes exhibited similar expression patterns with their RNA levels elevated relatively late during embryogenesis. Using immunohistochemistry PMP70 and catalase protein was localized largely to dorsal-anterior structures. Peroxisomal function was assayed with peroxisomal targeted-GFP, which when microinjected, revealed peroxisomes in dorsal-anterior structures at stage 45. A requirement for peroxisomal function appears to be present only late in development as organogenesis is finishing, yolk stores are depleted, and ingestion commences.     

知识模式转换在医学科技创新中的作用

医学科技创新是医院赖以生存与发展的动力,医学科技创新的过程也是医学知识模式不断转换的过程,本文从知识模式转换的视角,探讨知识管理对医学科技创新的意义与作用     

Magnetic and electrical stimulation of undulating nerve fibres: a simulation study

Mathematical models of myelinated nerve fibres are highly stylized abstractions of real nerve fibres. For example, nerve fibres are usually assumed to be perfectly straight. Such idealizations can cause discrepancies between theoretical predictions and experimental results. One well-known discrepancy is that the currently used models predict (contradictory to experimental findings) that an activation of nerve fibres is not possible with a pure transverse electric field. This situation occurs when a magnetic coil is placed symmetrically above a straight nerve fibre for magnetic nerve stimulation, or when an anode and a cathode are placed equidistantly on a line perpendicular to the fibre in the case of electrical stimulation. It is shown that this discrepancy does not occur if the physiological undulation of peripheral nerve fibres is included in the models. Even for small undulation amplitudes (e.g. 0.02 mm), it is possible to activate the fibre in these positions. For physiological undulations, as found in the literature, and favourable (off-centre) positions, the typical reduction of the thresholds is in a range between one and five, compared with perfectly straight fibres.     

Effects of priming duration on retention over the first 1 1/2 years of life

Exposing individuals to an isolated component (a prime) of a prior event alleviates its forgetting. Two experiments with 120 human infants between 3 and 18 months of age determined the minimum duration of a prime that can reactivate a forgotten memory and how long the reactivated memory persists. Infants learned an operant task, forgot it, were exposed to the prime, and later were tested for renewed retention. In Experiment 1, the minimum duration of an effective prime decreased logarithmically with age, but was always longer than the duration of a mere glance. In Experiment 2, the reactivated memory was forgotten twice as fast after a minimum-duration prime as after a full-length one, irrespective of priming delay and infant age. These data reveal that the minimum effective prime duration psychophysically equates the accessibility of forgotten memories. We conclude that priming is perceptually based with effects that are organized on a ratio (log) scale.     

踏跳瞬间足后部骨骼的三维有限元分析

目的建立足部三维有限元模型,对足后部骨骼在踏跳中的应力分布进行分析。方法应用CT扫描和CAD/CAM软件处理,建立足后部骨骼三维模型。通过对背跃式跳高踏跳的足底压力测量和逆向肌肉力量计算,确定载荷约束条件,并进行有限元计算。结果获得了踏跳瞬间,跟骨、距骨、舟骨等易损伤部位的生物力学响应和应力分布,发现跟骨后距关节,距骨背面均为应力集中处。结论本研究建立的模型可用于足后部骨骼生物力学研究,为踏跳中的运动损伤力学机理提供数据。     

高山红景天多糖对小鼠抗柯萨奇B5病毒感染能力的研究

对感染柯萨奇Ｂ５病毒（ＣＶＢ）小鼠模型研究结果表明，高山红景天多糖对发病小鼠心肌功能改善和免疫功能提高均具有明显的促进作用。增强了小鼠抗ＣＶＢ５感染的能力，并对由ＣＢＶ感染性疾病也有一定的防治作用。     

Septation of the respiratory and digestive tracts in human embryos: Crucial role of the tracheoesophageal sulcus

Esophageal atresia and tracheoesophageal fistula, common malformations of the respiratory and digestive tracts, are of unsettled pathogenesis. Part of the difficulty in understanding these abnormalities arises from the uncertainties about the normal developmental processes in the region. This study examined the development and fate of the tracheoesophageal septum. Normal human embryos from the Carnegie Embryological Collection and fetuses from the Hopkins Pathology Collection were examined, and reconstructions of selected specimens were made from photomicrographs of serial histologic sections. The results show that the lung bud appears in Carnegie stage 12, rapidly enlarges, and bend caudally, thereby producing a sulcus between the foregut and the respiratory system on its caudal aspect. The cranial aspect of this tracheoesophageal sulcus remains fixed at the levels of the first cervical vertebra throughout subsequent embryonic and fetal development. At the same time the trachea and esophagus elongate to bring those parts of the respiratory and digestive systems into their definitive anatomic positions. Examination of the tracheoesophageal sulcus shows that its growth-limiting properties may be explained by its catenoidal configuration. Catenoidal, or saddle-shape, sulci have been shown to have similar regional growth-limiting properties in the embryonic heart. These regions contrast with outwardly convex regions in both the developing heart and lung where growth of the tissues occurs. The observations made here suggest that the origin of the tracheoesophageal malformations must be sought in a configurational abnormality in the area of the developing lung bud in Carnegie stage 12. © 1994 Wiley-Liss, Inc.     

新生儿窒息史对儿童神经心理发育五项功能的影响

目的：分析有新生儿窒息史儿童五项神经心理发育测查结果，了解新生儿窒息对小儿神经心理发育的影响。方法：对有新生儿窒息史儿童98例分别于6月、12月、24月进行“小儿五项神经心理发育测查”，同时选择50例无新生儿窒息史、无其它重大疾病史儿童于相同月龄进行相同测量作对照，计算测得月龄与实际月龄的相差百分比平均值作标准化对比分析。结果：轻度窒息组57例与对照组无显著性差异，重度窒息组与对照组有显著性差异。结论：新生儿重度窒息对小儿五项神经心理发育有显著性影响。     

人文医学视域下构建《惠世医学人文素养》课程的教学实践

目的研究医学教育如何将人文精神内化于心,为医疗实践提供思路和方向。方法以《惠世医学人文素养》课程为载体,将心理营养教育融入人文教育,整体化教学整合人文和医学;应用Kirkpatrick模型从反应、学习、行为和结果等4个层次分析课程的教学效果。结果学生对课程满意度高;课程学习后学生增强了信息管理能力、团队合作能力、语言表达能力、自我发展能力等,提高了专业认知度,加强了职业认同感,在技能考核中展现了良好的人文关怀精神和优良的职业素质。结论《惠世医学人文素养》课程作为医学人文教育模式创新的有益尝试,有助于提高医学人文教育的有效性和针对性。