从二尖瓣瓣环三维形态的研究探讨合理的瓣环成形术

观察１５个固定心脏标本、１２个非固定心脏标本二尖瓣瓣环三维形态，运用动态三维超声心动图重建了１１名健康成年人的二尖瓣瓣环。发现二尖瓣瓣环为非平面的“马鞍”形，在心动周期中二尖瓣瓣环始终保持着程度不同的“马鞍”形。结果认为用硬质人工二尖瓣瓣环作瓣环成形术后的某些并发症，可能与改变了二尖瓣瓣环的天然三维形态有关。     

西脉式环抱器用于骨折内固定术护理配合要点

目的:探讨西脉镍钛形状记忆合金环抱器用于骨折内固定术有关的护理配合问题。方法:12例不同部位骨折病人(其中男性8例、女性4例、年龄15～62岁)采用西脉镍钛(TiNi)形状记忆合金环抱器人实施内固定手术,观察术中护理配合要点和实际效果。结果:骨折复位满意,手术持续时间<2h。所有病人术后均无感染迹象,手术切口愈合良好。结论:围术期护理配合质量(如器械选择、塑形准备、无菌操作等)的优劣,是手术成功与否的重要因素之一。     

用小鼠精子畸形试验评价正海生物膜遗传毒性的研究

目的用小鼠精子畸形试验评价正海生物膜引起遗传毒性的可能性。方法参照中华人民共和国国家标准《小鼠精子畸形试验》(GB15193.7-94)的方法及指导原则进行试验。结果正海生物膜三种浓度浸提液与阴性对照组相比小鼠精子畸形率无显著性差异(P>0.05)。结论正海生物膜用小鼠精子畸形试验评价不会引起遗传毒性。     

Keratoconus in monozygotic twins in New Zealand

We report on a case of keratoconus in identical twins who were brought up in Christchurch, New Zealand. Videokeratoscopy using an EyeSys^a (EyeSys Laboratories, Houston, Texas, USA) revealed not only marked differences in severity of keratoconus between the sisters, but also non-equivalent cone types. Both twin sisters reported an exacerbation of their keratoconus during pregnancy and during breast feeding. Various factors affecting the development and progression of keratoconus are discussed. (Clin Exp Optom 1995; 78: 4: 125–129)     

镍钛形状记忆合金内固定器治疗四肢骨折失败原因与对策分析

[目的]探讨镍钛形状记忆合金内固定器治疗四肢骨折的失败原因与对策.[方法]回顾分析镍钛形状记忆合金内固定器治疗四肢骨折259例中,8例术后出现内固定器松动、松脱、断裂的原因及处理方法.[结果]259例骨折患者中内固定失败8例,发生率3.1%;其中尺骨骨折1例、股骨骨折2例术后内固定器断裂,二次手术达骨性愈合;锁骨骨折2例,肱骨及股骨骨折各1例术后出现内固定器松动翘起,骨折畸形愈合;1例髌骨骨折骨折愈合后髌骨爪松脱.[结论]镍钛形状记忆合金内固定器治疗四肢骨折只有严格掌握手术指征,根据不同部位选择最佳的型号及长度,术中规范操作,术后进行安全的康复锻炼,才能避免内固定失败的发生.     

Image size magnification and power and dilation factors for optical instruments in general

Traditional treatments of spectacle magnification for distant objects consider only stigmatic spectacle lenses and they compare the retinal image size in a refractively fully compensated eye with the image size in the uncompensated eye. Spectacle magnification is expressed as a product of two factors, the power and shape factors of the lens. The power factor depends on the position of the entrance pupil of the eye. For an eye with an astigmatic cornea, however, the position of the entrance pupil is not well defined. Thus, the traditional approach to spectacle magnification does not generalize properly to allow for astigmatism. Within the constraints of linear optics and subject to the restriction that the eye's iris remains the aperture stop, this paper provides a complete, unified and exact treatment for optical instruments in general. It compares retinal image size in a generalized sense (including image shape and orientation) for any instrument in front of an eye with that of the eye alone irrespective of whether the instrument compensates or not. The approach does not make use of the concept of the entrance pupil at all and it allows for astigmatism and for non-alignment of refracting elements in the instrument and in the eye. The concept of spectacle magnification generalizes to the concept of instrument size magnification. Instrument size magnification can be expressed as the product of two matrix factors one of which can be interpreted as a power factor (as back-vertex power) and the other factor for which the name dilation factor is more appropriate in general. The general treatment is then applied to a number of special cases including afocal instruments, spectacle lenses (including obliquely crossing thick bitoric lenses), contact lenses, stigmatic systems and stigmatic eyes. In the case of spectacle lenses, the dilation factor reduces to the usual shape factor.     

Proximity factor in image size magnification for optical instruments in general

A general expression is derived for the proximity factor in near image size magnification for an arbitrary instrument in front of an arbitrary eye. The proximity factor is a 2 x 2 matrix. The instrument and eye may be astigmatic and have decentred elements. The image on the retina may be blurred or not. The analysis is exact within the limitations of linear optics. The general results are specialized for the case of a stigmatic instrument and a stigmatic eye. The results are applied to the case of a thick, possibly bitoric, spectacle lens. The Appendix treats two numerical examples.     

Regional cerebral activity associated with the incidental processing of pseudo-words

In order to study brain activity associated with “incidental” cognitive processing, regional cerebral blood flow (rCBF) was measured in six volunteers while they monitored a sequence of pseudo-words (e.g., FLOPE) for the rare occasions when the letters were displayed in blue rather than white. In the control condition, the same pseudo-word was presented repeatedly. In one experimental condition all 60 pseudo-words were different, while in the other there were 18 repetitions. Although it was not necessary to “read” the pseudo-words to perform the monitoring task, subsequent forced choice recognition memory for these stimuli was significantly greater than chance. Furthermore, there were significant differences in blood flow between the three conditions. When different pseudo-words were presented there was significantly greater activity in brain areas concerned with shape and object identity (extrastriate cortex bilaterally), with visual word form (left inferior temporal gyrus), and with articulatory word form (Broca's area) even though none of this information about the pseudo-words was needed for performance of the monitoring task. In the condition in which some of the words were repeated, there was significantly reduced activity in the right lingual gyrus. This area may therefore be a possible anatomical locus for repetition priming with verbal stimuli. These results indicate the importance of taking into account incidental processing when designing tasks for functional imaging experiments. © 1995 Wiley-Liss, Inc.     

Three-dimensional recording of the human face with a 3D laser scanner.

Three-dimensional recording of the surface of the human body or of certain anatomical areas has gained an ever increasing importance in recent years. When recording living surfaces, such as the human face, not only has a varying degree of surface complexity to be accounted for, but also a variety of other factors, such as motion artefacts. It is of importance to establish standards for the recording procedure, which will optimise results and allow for better comparison and validation. In the study presented here, the faces of five male test persons were scanned in different experimental settings using non-contact 3D digitisers, type Minolta Vivid 910). Among others, the influence of the number of scanners used, the angle of recording, the head position of the test person, the impact of the examiner and of examination time on accuracy and precision of the virtual face models generated from the scanner data with specialised software were investigated. Computed data derived from the virtual models were compared to corresponding reference measurements carried out manually between defined landmarks on the test persons' faces. We describe experimental conditions that were of benefit in optimising the quality of scanner recording and the reliability of three-dimensional surface imaging. However, almost 50% of distances between landmarks derived from the virtual models deviated more than 2mm from the reference of manual measurements on the volunteers' faces.     

Classification of Breast Masses Using Selected Shape,Edge-sharpness,and Texture Features with Linear and Kernel-based Classifiers

Breast masses due to benign disease and malignant tumors related to breast cancer differ in terms of shape, edge-sharpness, and texture characteristics. In this study, we evaluate a set of 22 features including 5 shape factors, 3 edge-sharpness measures, and 14 texture features computed from 111 regions in mammograms, with 46 regions related to malignant tumors and 65 to benign masses. Feature selection is performed by a genetic algorithm based on several criteria, such as alignment of the kernel with the target function, class separability, and normalized distance. Fisher's linear discriminant analysis, the support vector machine (SVM), and our strict two-surface proximal (S2SP) classifier, as well as their corresponding kernel-based nonlinear versions, are used in the classification task with the selected features. The nonlinear classification performance of kernel Fisher's discriminant analysis, SVM, and S2SP, with the Gaussian kernel, reached 0.95 in terms of the area under the receiver operating characteristics curve. The results indicate that improvement in classification accuracy may be gained by using selected combinations of shape, edge-sharpness, and texture features.