A binding study of phospholipase A2 with lecithin,lysolecithin and their tetrahedral intermediates using molecular modeling

We used molecular modeling to examine the binding of 1, 2-dioctanoyl-sn-glycero-3-phosphocholine (a lecithin), 1-octanoyl-sn-glycero-3-phosphocholine (a lysolecithin) and their tetrahedral intermediates in the catalytic site of phospholipase A₂ (PLA₂). We performed energy minimization on each complex, computed the binding energy, determined the relative binding energy among the complexes and calculated the difference in inter- and intramolecular energies of the components in the complexes. We found that the calculated orientation of the sn-1 ester bond of lysolecithin in the active site is similar to that of the sn-2 ester bond in lecithin, thus permitting PLA₂ to hydrolyze lysolecithin using the same mechanism as it uses to hydrolyze lecithin. On the other hand, the binding of lecithin is energetically more favorable by 4.5 kcal/mol than the binding of lysolecithin to the enzyme, and the binding of the lecithin tetrahedral intermediate is also energetically more favorable by 19.7 kcal/mol than the binding of the lysolecithin tetrahedral intermediate to the enzyme, which explains why lecithin is a better substrate than lysolecithin in the catalytic site. These results indicate that the activation energy for the hydrolysis of lysolecithin is higher than that for lecithin, consistent with the observed slower rate for the hydrolysis of lysolecithin.     

THE INCREASE OF FEMORAL ARTERIAL FLOW BY STIMULATING THE DORSAL AND VENTRAL MEDULLA IN CATS

1. In chloralose-urethane anaesthetized cats, the dorsal cardiovascular reactive area (DCRA) in the parvocellular reticular nucleus dorsomedial to the facial nucleus, and the ventral cardiovascular reactive area (VCRA) ventromedial to the facial nucleus, were stimulated by microinjections of sodium glutamate (100–200 nmol) or electric current. 2. Stimulation of DCRA, with a long latency of 15–20 s, elicited a marked increase of blood flow in the contralateral femoral artery with little change to moderate increase in systemic arterial blood pressure (ABP). In the relatively dorsal portion of DCRA, however, a smaller increase of blood flow in the ipsilateral femoral artery was elicited. 3. On the other hand, stimulation of VCRA with a short latency (3–5 s) evoked an increase of blood flow in both femoral arteries which was more prominent on the contralateral side. The responses were accompanied with decreases in the blood flow of other vascular beds with only a slight increase or minimal change in ABP. 4. The data suggest that DCRA and VCRA are both viscerotopically organized to alter the resistance of individual vascular beds for redistribution of blood flow.     

The use of frame fixation in the management of open distal extensor mechanism avulsion fracture in a dislocated knee

An avulsion fracture of the tibial tubercle is a common injury in traffic accident. If the fracture is closed, then a comparatively good prognosis can be expected through reinforcement of the bone via osteosynthesis and the use of artificial ligaments. In this case, an open wound was observed in the tibial tubercle, and the wound was so polluted that the healing process was significantly delayed. It was therefore difficult to provide simultaneous surgical treatment and so three operations were required to perform the reconstruction of the extensor mechanism. The reconstruction of extensor mechanism and the frame fixation between the patella and tibia was performed. Six months after the injury, the patient was able to walk without aid, had a range of movement from 5°to 130°, and did not show any indications of ADL disorder. Using this method of frame fixation between the patella and tibia proved to be an effective technique for the reconstruction of the open knee extension mechanism injury.     

Rapid effect of stress concentration corticosterone on glutamate receptor and its subtype NMDA receptor activity in cultured hippocampal neurons

Objective: To study the rapid effect of glucocorticoids (GCs) on NMDA receptor activity in hippocampal neurons in stress and to elucidate its underlying probable membrane mechanisms. Methods: Whole-cell patch-clamp recording was used to assess the effect of stress concentration corticosterone (B) on the responses of cultured hippocampal neurons to glutamate and NMDA (N-methy-D-asparatic acid). To make clear the target of B, intracellular dialysis of B(10μmol/L)through patch pipette and extracellular application of bovine serum albumin-conjugated corticosterone (B-BSA, 10μmol/L)were carried out to observe their influence on peak amplitude of NMDA-evoked current. Results: B had a rapid, reversible and inhibitory effect on peak amplitude of GLU-or NMDA-evoked current in cultured hippoeampal neurons. Furthermore, B-BSA had the inhibitory effect on INMDA as that of B, but intraeeUularly dialyzed B had no significant effect on INMDA. Conclusion: These results suggest that under the condition of stress, GCs may rapidly, negatively regulate excitatory synaptic receptors-glutamate receptors (GluRs), especially NMDA receptor (NMDAR) in central nervous system, which is mediated by rapid membrane mechanisms, but not by classical, genomic mechanisms.     

心肌炎的免疫学作用机制

病毒感染引起的心肌炎临床最为常见,其中半数以上由柯萨奇B组病毒所致。然而,迄今为止,其发病机制尚未完全明了,病毒感染对心肌细胞的直接损伤作用及病毒介导的免疫损伤作用是目前认为最有可能的机制,因此,了解心肌炎的免疫学机制具有重要的理论和实践意义。     

妇宝胶囊止血机制的实验研究

目的:通过观察妇宝胶囊对动物出凝血时间、血液凝固系统的影响,探讨妇宝胶囊的止血机制。方法:采用毛细玻璃管法测定小鼠凝血时间(CT),用断尾法测定出血时间(BT);用ACL-200型血液凝集仪测定大鼠凝血酶原时间(PT)和部分凝血活酶时间(APTT)。结果:妇宝胶囊能明显缩短小鼠CT、BT,缩短大鼠PT和APTT。结论:妇宝胶囊的止血机制主要通过促进内源性和外源性凝血系统,抑制纤维蛋白溶解系统达到目的。     

失眠症患者心理防御机制与社会支持的相关研究

目的　探讨失眠症患者心理防御特征和社会支持 ,并分析两者的关系。方法　采用心理防御方式问卷 (DSQ )、社会支持评定量表 (SSRS)对失眠症患者和正常健康者各 5 0例进行评定。结果　患者组心理防御方式 (不成熟型、中间型防御因子和掩饰因子的因子分高 ,成熟防御因子分低 )和社会支持 (社会支持总分、主观支持分、对支持利用度低 )与对照组相比差异有显著性 (P <0 .0 5或 0 .0 1) ;相关分析发现 ,患者组不成熟防御机制与SSRS的支持总分、主观支持分、对支持利用度呈负相关 (P均 <0 .0 5 ) ,中间型防御机制与SSRS的主观支持呈负相关 (P <0 .0 5 )。结论　失眠症患者心理防御机制的成熟程度较正常人低 ,社会支持差 ,两者存在一定的关系。     

Event-related potential correlates of functional hearing loss: Reduced P3 amplitude with preserved Nl and N2 components in a unilateral case

Abstract A female patient exhibiting functional hearing loss in her left ear demonstrated reduced amplitude of P3 component in event-related potentials (ERP) to left monaural stimulation, with preserved N1 and N2 components to stimulation of either ear. This result suggested that stimuli in the affected ear were conducted successfully up to the auditory cortex but that further processing in higher brain regions was 'repressed'. Event-related potential examination for such hysterical disorders could be useful in clarifying their brain mechanism and offer a useful diagnostic clue to its nature.     

Health insurance and private providers: A study of the civil servants' medical benefit scheme in bangkok,Thailand

Compulsory health insurance schemes have received attention recently as a means of creating a reliable extra-budgetary source of health care funding. Yet, the full implications of such schemes in a developing country context are unclear; in particular, the impact on and relationship with private sector providers has infrequently been explored. This study examines patterns of public and private sector utilization under the Civil Servants' Medical Benefit Scheme (CSMBS) in Bangkok, Thailand. The CSMBS currently provides limited reimbursement for private inpatient care, but recent proposals suggest increasing benefit levels for care sought in the private sector. The study shows that despite high level of cost recovery in the public sector, charges were much lower than those in the private sector. Different patterns of diagnosis in the two sectors were found with private hospitals tending to treat a less complex case mix. Within the private sector, there was a limited tendency to specialize in certain types of care. It is concluded that under the current payment mechanism of fee-for-service reimbursement, measures to enhance access to private sector care should be approached with caution. In the long run, the scheme should merge with the recently established social security scheme.     

屈膝过程中的胫股运动特性分析

本文采用三维位移测量方法，测试１０例离体人膝标本的胫股关节三维运动特性。发现屈膝过程中，胫股运动也具有典型的三维运动特点。其中在屈膝初期的３０°内，胫骨内旋最明显并伴有胫骨内翻现象，平均内旋８°，内翻６－７ｍｍ，膝关节完全伸直时胫股扣锁使膝关节稳定，屈曲时胫股“解锁”使膝关节松弛，具重要的临床意义，同时提示，在解释传统的胫股扣锁现象时不应遗漏伴随发生的胫骨内／外翻现象。