迷宫学习模型实验的时反应量-效关系

目的　分析学习记忆动物行为模型实验的时反应量 效关系指标。方法　应用Y型迷宫刺激器对大鼠进行空间学习记忆的行为模型实验。结果　测得大龄组 (约 12月 )和小龄组 (<4月 )大鼠达到学会标准前所需的刺激次数分别为 (32 .6 2± 2 0 .5 9)次 (n =2 1)和 (2 0 .6 2± 14.2 5 )次 (n =2 1,P <0 .0 5 ) ,学会时 9次正确反应的潜伏期分别为 (7.44± 2 .89)s和 (6 .93± 1.49)s(P >0 .0 5 ) ,并观察到刺激次数与逃避到安全区的潜伏期呈类双曲线型时反应量 效关系、刺激次数与移动正确率呈非线性正变关系。结论　迷宫学习模型实验存在特殊类型的时反应量 效关系。     

医学伦理学教学模式探讨

医学伦理学是医学科学和伦理学科学交叉的边缘科学 ,是医学道德的科学 ,是一般伦理学原理在医学实践中的具体运用。培养合格医学生 ,不仅要注重医学知识的教育 ,而且要重视医学伦理道德的引导和培养。本文从教育的目的、原则、内容及教学方法等方面探讨医学伦理学的教学模式 ,旨在从理论到实践提高医学生的医德修养     

一种新的基于全口义齿测量的牙列缺失修复用颌位记录托盘

目的 测量全口义齿的相关特征数据,并以此设计用于牙列缺失患者全口义齿修复的一种新的,可记录各种参数的颌位记录托盘.方法: 对100副在临床应用的全口义齿,测量双侧上颌第一磨牙中央窝间距a1,上颌第一磨牙中央窝连线至义齿前缘距离a2,上颌义齿宽度a3,上颌义齿长度a4,右上颌第一磨牙近中舌尖至基托组织面高度a5₁,右下颌第一磨牙中央窝至基托组织面高度a5₂,上唇系带切迹至上颌中切牙切端连线的高度a6,上中切牙区唇侧基托最薄处厚度a7,并以此设计颌位记录托盘支撑杆孔间距b1,支撑杆孔至托盘前缘距离b2,托盘宽度b3,托盘长度b4,上颌后牙区托台高度b5₁,支撑杆高度b5₂,前部手柄高度b6,前部手柄厚度b7,以制作不同型号的颌位记录托盘.结果: 各组数据的最小值,平均值,最大值(单位:mm)分别如下:a1:37.1,44.5,59.6;a2:22.6,29.0,38.1; a3: 48.5,58.2,76.6; a4: 37.4,50.8,61.0; a5₁: 5.6,9.5,14.7; a5₂: 3.8,9.9,18.8; a6: 8.9,16.6,24.7; a7: 1.2,2.8,5.9.设计大,中,小3种号型的颌位记录托盘.临床应用时,首先在托盘组织面用硅橡胶重衬,托台平面和前部手柄下缘确定牙合平面;继而安装下颌支撑杆,旋转螺丝至合适的垂直距离;然后在支撑杆前后放置硅橡胶,确定水平关系;最后在前部手柄唇侧画线标记面部中线及微笑,静息时上唇下缘位置.结论: 本研究测量的全口义齿数据对分析修复空间提供了参考,本研究设计的托盘为无牙颌患者全口义齿修复时确定颌位关系提供了一种新方法.     

Acute dose-effect relationships of caffeine and mental performance,EEG, cardiovascular and subjective parameters

The present study investigated the dose-effect relationship of caffeine on mental performance using a caffeine-sensitive rapid information processing task (RIP) in a pre/post cross-over design. Twenty female nonsmoking regular coffee drinkers received 0, 1.5, 3 and 6 mg/kg caffeine in a balanced order and the measurements were extended to cardiovascular, EEG and mood parameters. Surprisingly, the dose-effect curves for the different parameters were rather heterogeneous. Whereas increasing effects with increasing caffeine doses were observed for - and -EEG frequencies, anxiety, wakefulness, and some coffee ratings, negative dose-effect relationships were obtained for RIP processing rate and blood pressure. No apparent dose-effect relationships were seen for reaction time and motor activity. Thus, it was concluded that the dose-response relationships are rather shallow and heterogeneous and that the different parameters have different ranges in which they are sensitive to caffeine. The caffeine doses which might have beneficial behavioral effects are at the lower end of the tested dose range and comparable to those found in caffeine-containing beverages.     

Pharmacodynamics of Phenobarbital Anesthesia and Pentylenetetrazol-Induced Maximal Seizures in a Rat Model of Neoplastic Spinal Cord Compression

The purpose of this investigation was to determine whether paraplegia induced by neoplastic cord compression affects the pharmacodynamics of phenobarbital general anesthesia or of pentylenetet-razol (PTZ)-induced convulsions. Paraplegic rats harboring a thora-columbar epidural tumor, or an identical hindlimb tumor mass, received an i.v. infusion of phenobarbital until the onset of anesthesia. At that point, the phenobarbital concentrations in the CSF and serum were measured. Similarly, PTZ was infused until the onset of maximal seizures. It was found that changes related to systemic tumor growth and newly developed paraplegia due to neoplastic spinal cord compression did not attenuate the pharmacodynamics of phenobarbital. However, sustained paraplegia of 4 days duration reduced CNS sensitivity to the hypnotic action of the barbiturate as evidenced by the higher cerebrospinal fluid phenobarbital concentration required to induce anesthesia (170 ± 31 vs 125 ± 20 mg/L; P < 0.05). On the other hand, sustained paraplegia did not affect brain threshold concentration for PTZ-induced seizures.     

Structure-activity relationships and conformational features of antiherpetic pyrimidine and purine nucleoside analogues. A review

A rational approach to the design of antiherpetic nucleoside analogues is based in part on the broad specificity ol virus- coded thymidine kinases. Herpes virus thymidine kinase activates many 5-substituted 2-deoxyuridines, analogues ol thymidinc (e.g., idoxuridine, trifluridine, edoxudine, brivudine), 5-substituted arabinofuranosyluracil derivatives (e.g., 5-Et-Ara-U, BV-Ara-U, Cl-Ara-U), acyclonucleosides of guanine (e.g., aciclovir, ganciclovir, penciclovir), and purine nucleosides with the penlafuranosyl ring replaced by a cyclobutane ring (e.g., cyclobut-G, cyclobut-A). Activation involves selective, and frequently regiospecific, phosphorylation ol these analogues to the 5-monophosphales. These are further phosphorylated by cellular enzymes to the 5-triphosphates, which are usually competitive inhibitors of the viral-coded DNA polymerases. Some analogues are also incorporated into viral, and to a lesser extent cellular, DNA. A recent, unusual, exception is human cytomegalovirus, which does not code for a thymidine kinase, but for a protein with the sequence characteristics of protein kinase and which phosphorylates ganciclovir to its 5-monophosphate. The interaction of the analogues with cellular catabolic enzymes such as uridine and thymidine nucleoside phosphorylases is also discussed, as is the relationship between physicochemical properties (configuration, conformation, electronic and hydrophobic parameters) and antiviral activities, with particular reference to those drugs that are licensed, or under consideration, for clinical use.     

Law-like relationship between height and weight of school children

Ehrenberg’s Law-like relationship between height and weight [log was applied to a group of public school and Govt. school children in New Delhi. It was found that the model log was comparatively a good fit for public school children and the model log for Govt. school children. On fitting the model to the sample data it was found that the value of ‘a’ was 0.8, with some minor variation in the second decimal point and the value of ‘b’ was 0.39 & 0.36 respectively for public school boys and girls and 0.32 & 0.29 respectively for Govt. school boys & girls. These results corroborates with the findings of the earlier studies that the intercept constant ‘b’ in the Law-like relationship equation is influenced by the nutrition of children. This model is recommended because of its simplicity and practical usefulness using only already available information.     

Isovelocity investigation of the lengthening behaviour of the erector spinae muscles

The purpose of this study was to investigate the force-velocity (F/) relationship for the erector spinae muscles in submaximal activation movements, with particular attention to their response during lengthening movements and at lower shortening contraction velocities. Dynamic models that predict lower back muscle forces require reasonable representations of the modulating effect of instantaneous velocity. Ten males were observed performing trunk flexion and extension in the sagittal plane under constant load. Contraction velocities were measured as the first derivative from a devise sensitive to changes in spine curvature, and controlled by a visual feedback system while a constant load was applied through a chest harness. The erector spinae exhibited a yielding phenomenon which causes an abrupt drop in force during constant velocity stretching under constant, submaximal, stimulation. The findings were consistent with previous isovelocity muscle lengthening experiments. Yielding appeared dependent on the level of load/activation supporting the theory of a state-variableF/ relationship. The eccentric behaviour of the lower erectors (L3) seemed independent of velocity and length, while that of the upper erectors (T9) showed a dependence on length. At lower concentric velocities, concavity in torque-velocity curves was noted after a threshold velocity. The findings of this study strongly reinforce the notion that theF/ length relationship is not a continuous hyperbolic relationship during muscle shortening and that the commonly modelled force augmentation effect of lengthening is incorrect, at least for submaximal activation of the extensors of the lower back.     

Towards an ethics of immediacy A defense of a noncontractual foundation of the care giver—patient relationship

In this article, I argue that the relationship between patients and their health care providers need not be construed as a contract between moral strangers. Contrary to the (American) legal presumption that health care providers are not obligated to assist others in need unless the latter are already contracted patients of record, I submit that the presence of a suffering human being constitutes an immediate moral commandment to try to relieve such suffering. This thesis is developed in reference to the French philosopher Levinas and the Dutch theologian Schillebeeckx. An expanded version of the biblical parable of the Good Samaritan serves as test case.This revised version was published online in October 2005 with corrections to the Cover Date.     

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