New thoughts on normal tension glaucoma.

Normal tension glaucoma (NTG) is considered a primary optic neuropathy within the glaucoma family. Whereas NTG shares many of the same pathologic characteristics as primary open angle glaucoma (POAG), there are several differences such as pattern of visual field defect and incidence of disc hemorrhaging. The most notable difference is that NTG does not manifest a recordable intraocular pressure (IOP) greater than 21 mmHg. Debate has existed as to whether NTG is a pressure-sensitive neuropathy and if pressure reduction affects the course of the disease. Likely, there are aspects in the pathophysiology of NTG that are both pressure sensitive and insensitive, and the etiology of NTG has never been adequately explained.     

应用张力带固定法治疗锁骨远端骨折

目的：评价张力带固定法治疗锁骨远端骨折的临床效果。方法：对20例锁骨远端骨折行切开复位后张力带固定法治疗。术后随诊分析。结果：所有骨折均在半年内愈合。患侧肩关节功能恢复良好。无一例出现伤口感染。结论：张力带固定治疗锁骨远端骨折是一种简单可靠的手术方法。     

单纯髌骨腱膜缝合术治疗髌骨骨折44例

目的 讨论单纯髌腱缝合术治疗髌骨骨折压应力、张应力、聚合力的关系。方法 采用单纯髌前腱膜缝合术治疗髌骨骨 折44例,术后患肢165°～175°半屈曲位固定。结果 术后3个月功能恢复情况与髌骨内固定半年后膝关节活动功能相当。结 论 单纯髌前腱膜缝合术方法简单、能促进膝关节功能早期恢复及不需二次手术取内固定的优点。     

充填式无张力疝修补术后复发的预防

目的　探讨充填式无张力疝修补术后复发的原因及对策。方法　通过对 1 0例腹股沟斜疝病人经疝环充填式无张力疝修补术后复发情况的研究。结果　网塞和补片的放置缝合欠佳及术后存在腹内压增高因素是引起复发的主要原因。结论　减少疝环充填式无张力疝修补术后复发应改进网塞和补片的固定方法及控制腹内压增高因素     

Delayed intraventricular tension pneumocephalus complicating posterior fossa surgery for cerebellar medulloblastoma

A child is described in whom intraventricular tension pneumocephalus developed 10 days after removal of a cerebellar medulloblastoma and 1 day after suture removal. The tension pneumocephalus was associated with hydrocephalus and CSF leakage from the suture line. The symptoms of the pneumocephalus were rapidly progressing loss of consciousness and hemiplegia which were promptly reversed upon aspiration of the intracranial air. A large amount of intraventricular air present in the immediate postoperative period was, however, clinically silent. The characteristics of this unusual presentation, its relation to asymptomatic pneumocephalus. hydrocephalus and the preventive and therapeutic measures required to deal with such conditions are discussed.     

多从动轮带传动设计计算若干问题的探讨──兼与“机械设计手册”有关章节作者商榷

对多从动轮带传动的适用范围、包角要求及计算公式作了适当的修正。导出的从动轮最小匹配包角的计算公式和相应的线图，简化了打滑条件的验算，有助于设计中对包角的选择。     

Some features of different motor units in human biceps brachii

Summary Use has been made of the method of selective leading-off of impulses from individual motor units at high isometric muscle tension, the maximum one including. Two types of motor units have been distinguished in m. biceps brachii in man on the basis of the dependence between the firing frequency and the level of the muscle tension. Characteristic of the first (tonic) type is the rise in the frequency at lower tensions and constant frequency at higher tensions. The second (phasic) type shows an approximately linear rise of the frequency with increase of tension. The tonic motor units are smaller in size, with lower threshold, they are less fatiquable and their transient pattern of firing depends on the rate of increase of tension. They contribute less to the growth of the muscle tension. The phasic motor units are bigger in size with higher threshold, more fatiguable, their transient pattern of firing does not depend on the rate of increase of tension. They contribute essentially to the growth of the muscle tension.     

Anterior cruciate ligament replacements: a mechanical study of femoral attachment location, flexion angle at tensioning, and initial tension

We examined three surgical variables that affect the ability of an anterior cruciate ligament replacement to restore the limit of anterior tibial translation. These were the placement site of the substitute on the femur, the initial tension applied to the replacement, and the flexion angle of the knee at the time of tensioning. An anterior load of 100 N was applied to the tibia. As the knee was flexed, we measured the tensile force in the substitute and the anteroposterior position of the femur relative to the tibia. Placement largely determined whether the force in the replacement increased or decreased with flexion. Placement also largely determined whether the tibia moved anteriorly or posteriorly with flexion compared to its position in the intact knee. The initial tension and the flexion angle at tensioning affected the magnitude of force in the substitute and the magnitude of the change in AP position. They did not affect how force and AP position changed with flexion. Greater increases in force and greater posterior shifts in tibial position were produced by changing the flexion angle at tensioning from 0 degrees to 30 degrees than by increasing the initial tension from 22 to 44 N.     

Relations between tensile impact properties and microstructure of compact bone

Summary Standardized human and beef femoral compact bone specimens were tested in tensile impact and the dynamic mechanical properties were determined. The microstructure of 45 beef and 47 human bone specimens were examined histologically to determine if there is a structural basis to account for strength differences in the bone samples. Strong negative correlations were obtained between the maximum stress and the percentage area of secondary osteons in each specimen. For human bone samples, the energy absorption capacity and the modulus of elasticity were also found to have strong negative correlations with the percentage area of secondary osteons present in each specimen. Linear regression equations were obtained describing the impact strength properties in terms of the percentage areas of secondary osteons and cavities in the samples.Fracture surfaces of the tested bone specimens were examined in a scanning electron microscope. Most surfaces exhibited a fairly rough texture indicating a quasi-cleavage type of failure. Fractographic analysis of bone fracture surface was helpful in understanding the micromechanics of bone fracture.Presented in part at the 21st Annual Meeting of Orthopaedic Research Society     

The relation between erythrocyte deformability,cell shape,and membrane surface tension

Summary Erythrocytes which have been transformed into spheres by the action of surface-active substances, such as bile or free fatty acids, are more rigid than normal red cells, as is shown by viscosity measurements and microscopic observation. The rheological differences between biconcave and sphered red cells are considered to depend upon the degree of membrane stretching, which is maximal in the normal red cell and lowered in the sphered erythrocyte. Because the stretching of the cell membrane is probably caused by a surface tension between plasma and cell surface, red-cell deformability depends, among other things, upon the composition of the plasma.