Developing a model for clinical and basic science teaching skills

This report describes a model for identifying sets of teaching abilities considered to be effective for medical school teaching staff, based on roles teachers assume and functions they are expected to perform as instructors. The specification of these teaching abilities was the first step in the development of a comprehensive course on Medical Instruction at the Basic Institute of Medical and Agricultural Biology of the State University of Sao Paulo, Botucatu, Brazil, where the senior author is employed. The work was based on the assumption that medical school teachers are expected to assume a variety of teaching roles and that identification and specification of the abilities that define their roles can result in more effective and efficient teaching.     

卵圆孔未闭动物模型的建立

目的 探讨采用正常中华小型猪制作卵圆孔未闭动物模型的可行性。方法 中华小型猪11只，选取1只行预实验，10只用于正式实验。全身麻醉下，经股静脉送入Rups-100穿刺针系统，在透视引导下穿刺房间隔卵圆窝，然后对穿刺点行球囊扩张术。预实验动物术后1d处死，正式实验组动物术后21d处死。心脏取材，行病理检查。结果 11只猪均成功行房间隔穿刺和球囊扩张术，并经心房造影证实建立卵圆孔未闭模型。正式实验组动物除1只术中出现心包积液外，其余术中及术后均无并发症。预实验动物于处死后肉眼观房间隔卵圆窝有-0．7cm×0．8cm缺损，光学显微镜下见红细胞聚集。正式实验组动物于处死后观察，7只可见房间隔卵圆窝愈合，3只分别残留0．1cm×0．2cm、0．2cm×0．2cm、0．1cm×0．3cm缺损。正式实验组动物无论卵圆窝是否愈合，光学显微镜下在穿刺点周围均可见不同程度的局灶性心内膜增生和缺失、淋巴细胞聚集、心肌细胞肿胀、坏死和间质纤维化。结论 采用房间隔穿刺和球囊扩张的方法，用中华小型猪建立卵圆孔未闭模型是可行的。     

鼠骨关节炎动物模型建立的现状

骨关节炎(osteoarthritis，OA)是临床上常见的疾病。探索骨关节炎动物模型的建立方法，是研究其病因和治疗方法的重要课题之一。鼠是一种理想的动物，所用的方法有关节内手术、关节内注射、关节外手术等，各种方法都有自己的长处和不足。本文就鼠骨关节炎动物模型的建立方法、模型特点及其应用等方面进行综述。     

内皮素性大鼠门静脉高压模型的建立

目的： 建立内皮素-1(ET-1)引起门静脉压力升高的动物模型。方法: 正常雄性SD大鼠48只，随机分为生理盐水组、ET-1低剂量组(0.3 μg/kg)，ET-1中剂量组(1.0 μg/kg)和ET-1高剂量组(3.0 μg/kg)。生理盐水组大鼠经股静脉注入生理盐水，其余各组大鼠按相应剂量经股静脉注入ET-1溶液，观察门静脉压力和颈动脉压力的变化情况,并筛选出能使门静脉压力升高最适宜的剂量；另取15只大鼠随机分为对照组、ETAR阻断剂(BQ-123)组和ETBR阻断剂(BQ-788)组，实验开始前30 min经各组大鼠股静脉分别注入生理盐水、ETR阻断剂BQ-123(给药剂量为12.5 μg/kg)和BQ-788(给药剂量为15 μg/kg)，然后以选定的适宜剂量匀速注入ET-1溶液，观察各组大鼠门静脉压力变化。结果: 不同剂量的ET-1均能使门静脉压力升高，尤以高剂量组最为明显；而提前注入ETR阻断剂之后，再注入ET-1溶液门静脉压力虽然升高，但升高的幅度较小。结论: 成功创建了内皮素性大鼠门静脉高压模型，此模型可用于研究ET-1在PHT发病机制中的作用和药物对PHT时血中ET-1的影响。     

Conditioned taste aversion using four different means to deliver sucrose to rats

A solution of sucrose either to be drunk from a drinking tube-self-drinking procedure (SD)-or perfused intraorally as a consequence of nose-pokes-self-administration procedure (SA)-or perfused as a consequence of licking an empty tube (LA)-was paired with an LiCl-induced malaise in rats. The effects were compared to those of a procedure consisting of intraoral administration (IO) of sucrose not contingent to any specific action of the rat. Similar levels of conditioned taste aversion (CTA) were obtained but extinction in the IO procedure was quicker than in the SA procedure, which was itself quicker than in the SD procedure. Extinctions in the IO and LA procedures resembled one another and were quicker than in the SD procedure. A step towards deciding between several explanatory hypotheses of these differences was made by conducting two more experiments. The third experiment was based on reinstatement, or not, of the conditioning procedure for the test after standard IO extinction. CTA was produced only when SD was used both at conditioning and test. A fourth experiment was based on latent inhibition where the procedure was changed, or not, between preexposure and conditioning. Latent inhibition was absent only when the rats had been preexposed to sucrose with the SA procedure and conditioned with the SD procedure.     

Investigation and comparison of some models for removing ocular artefacts from EEG signals

An investigation of ocular artefacts (OAs) in the human electroencephalogram (EEG) to quantify the effectiveness of OA removal and to find the most effective model for removing OAs online is described. In Part 1, the models used in the investigation are described and the data analysed. The analysis showed that the ‘true’ EEG exhibited a high degree of serial correlation and so the ordinary least-squares (OLS) method employed to remove OA was inefficient. Efficient alternative methods based on autoregressive models of the ‘true’ EEG are discussed. It is also shown that the EOGs are linearly dependent making some of them redundant. In Part 2, the models are compared.     

Orientation of the peptidoglycan chains in the sacculus of Escherichia coli

The organization of chains of oligopeptidoglycan in the saccular wall is of critical importance in the study of the mechanism and physiology of prokaryotic wall growth. The electron microphotographs of De Pedro et al, present new findings and can be used to negate or at least raise questions about the previously accepted conclusion that the glycan chains are oriented transversely to the axis of rod-shaped Escherichia coli. This suggests caution in assuming that the glycan chains in the murein structure are parallel to each other and are perpendicular to the axis of the cell.These results should reopen the question of not only the orientation of the peptidoglycan chains, but the possibility of variability in orientation. Three classes of hypotheses about wall growth are reconsidered and problems with them are presented. The new results from De Pedro's laboratory and the experimental glycan chain length distribution argue against proposed systematic models. These include models that postulate belts or hoops stretched around the circumference of the cell and mechanisms that insert new chains of the length of presumptive “docking” strands in the stress-bearing wall. They are consistent, however, with the surface stress theory that proposes that random enzyme action together with physical forces are involved in the elongation of the rod-shaped Gram-negative wall.     

Pseudorandom testing technique for the characterization of local hemodynamic control

Summary In order to investigate the low frequency properties of renal and femoral hemodynamic variables, pseudorandom testing techniques were used. The arterial flow of each bed, in separate experiments, was modulated by a low amplitude signal based on a pseudorandom binary sequence (PRBS) generated by digital computer.The cross-correlation functions between input flow and arterial pressure, venous pressure, and venous flow exhibit damped oscillations in all cases. These responses are parameterized in terms of a damping ratio () and an undamped natural frequency _n for a second order model. The parameters of the model are dependent upon the state of the bed as defined by mean arterial and venous pressures, mean flow through the bed, resistance, and oxygen consumption.The results of this study offer further insight into the dynamic low frequency autoregulation phenomenon for the renal and femoral beds of the dog.Supported by NIH Grant HE 11747.