角膜地形图与角膜曲率计在白内障手术前后评价

本文应用计算机辅助的角膜地形图系统TMS-1和角膜曲率计TOPCONOM-4同时测定了200例(278眼)的角膜地形图和中央角膜屈光状态。比较了角膜地形图的模拟角膜曲率SIMK值和角膜曲率计的垂直和水平屈光度。结果显示,白内障术前组116例150眼的SIMK平均值分别为44.22D(垂直轴)和44.26D(水平轴),角膜曲率计的中央屈光度垂直轴平均为44.16D,水平轴为44.23D。统计学处理表明,2种组方法的结果之间差异无显著性(P>0.05),第2种术后组67例90眼的SIMK平均值分别为46.37D(垂直轴)和43.06D(水平轴),角膜曲率计的中央屈光度垂直轴平均为46.09D,水平轴平均为42.88D,统计学处理二种方法的结果之间差异无显著性(P>0.05)。研究提示,角膜地形图系统的模拟角膜曲率SIMK值和角膜曲率计的屈光度无论在白内障手术前还是在手术后其结果是一致的,临床应用具有同等的价值。但是,当角膜中央屈光度异常范围小于3毫米,角膜混浊,角膜严重不规则散光时,角膜曲率计不能满足临床需要。而计算机辅助的角膜地形图系统则具有极大的诊断及检测价值。眼科学报 1994;10:85—89。     

Quantitative structure-activity relationships in MAO-inhibitory 2-phenylcyclopropylamines: Insights into the topography of MAO-A and MAO-B

Ten (E)-and (Z)-isomers of 2-phenylcyclopropylamine (PCA), 1-Me-PCA, 2-Me-PCA, N-Me-PCA, and N, N-diMe-PCA and fifteeno ⁻, m⁻, p⁻ isomers of (E)-PCA with substituents of Me, Cl, F, OMe, OH were synthesized in this laboratory and tested for the inhibition of rat brain mitochondrial MAO-A and MAO-B. The effects of substituents, their positions, and stereochemistry on the inhibition were assessed for the compounds with substituents at cyclopropyl and amino groups and QSAR analyses were performed using the potency data of ring-substituted compounds. The best correlated QSAR equations are as follows: pI₅₀=0.804 Π² Blo−1.069 Blm+0.334 Lp−1.709 HDp+7.897 (r=0.945, s=0.211, F=16.691, p=0.000) for the inhibition of MAO-A; pI₅₀=1.815 π-0.825 Π² R+0.900 Es²+0.869 Es³+0.796 Es⁴−0.992 HDp+0.562 HAo+3.893 (r=0.982, s=0.178, F=23.351, p=0.000) for the inhibition of MAO-B. Based on the potency difference between stereoisomers of cyclopropylamine-modified compounds and on QSAR results, it is proposed that the active sites of MAO-A are composed of one deep hydrophobic cavity near para position, two hydrophobic cavities interacting with Me group, a hydrophobic area accomodating phenyl and cyclopropyl backbone, steric boundaries, a hydrogen-acceptor site near para position, and an amino group binding site and that in addition to the same two hydrophobic cavities, hydrophobic area, steric boundaries, hydrogen-acceptor site, and amino group binding site, another steric boundary near para position and a hydrogen donating site near ortho position constitute active sites of MAO-B.     

Polyethylene wear in primary knee arthroplasty

Abstract Polyethylene (PE) wear is a focal issue in joint replacement, so it is essential to understand how it takes place in vivo. PE wear is a multifactorial process with a complex interaction of variables related to the materials used, the mechanical conditions, operative procedures for implantation, activity of the patient and use of prosthesis. We retrieved 65 PE inserts with the respective femoral and tibial components (50 inserts of total knee prostheses and 15 monocompartmental prostheses) from first revision surgeries. The average age of the patients was 68.3 years; the average time to revision was 41.5 months. Macroscopic observation considered the grade, topography and type of wear. Degradation was also studied with scanning electron microscopy. No direct relationship was found between the level of wear and the survival of total or monocompartmental knee prostheses. The duration of 11 (22%) total prosthetic inserts with grade 2 wear was 42.6 months vs. 51.5 months of 17 (34%) total inserts with grade 1 wear. However, study of the relationship between wear grade and wear topography in total inserts suggested that there was a significant connection. In fact, the 22 (44%) prostheses with central and symmetrical wear never showed wear greater than grade 1. Instead, of the remaining 28 prostheses (56%) without central and symmetric wear, only 3 had grade 0 wear. Finally, considering the relationship between wear grade and type of wear, all 18 inserts (27.7%) with grade 2 or 3 wear had 100% delamination. In conclusion, this study suggests that the correct positioning of the prosthetic components, besides its quality, is an important cause of polyethylene wear.     

A corneal model for slit-scanning elevation topography

Computerised videokeratography is increasing in sophistication and accuracy. The Orbscan II Videokeratographer combines the advantages of Placido derived and slit-scanning derived topography, to acquire shape information on the posterior surface of the cornea. The purpose of this paper is to construct a model of slit-scanning elevation topography and highlight potential sources of variation in this methodology. Ray tracing calculations were performed on a defined, theoretical, spherical model to obtain a pachymetric measurement. These calculations were tested by comparing the pachymetry measurement derived from the model, over a refractive index shift from 1.376 to 1.400 with the pachymetry measurement obtained by Orbscan II, of a human eye, with an identical alteration in refractive index. The two methods of measurement differed by only 0.157 microm, suggesting that the model is a good representation of slit-scanning elevation topography, and that refractive index variations have only a minimal effect on Orbscan II pachymetry measurement.     

Some Guidelines for the Use of Stimulus Modifications in Teaching Response Topography to People with Developmental Disabilities

The use of stimulus modifications in teaching involves altering the materials of a task in order to simplify its execution. Though their use in teaching stimulus discriminations to people with developmental disabilities has been extensively investigated, less attention has been given to their utilization in teaching response topography. This paper offers some general guidelines about their use for this purpose. In relation to their design, it is suggested that the aim should be to reduce the demands made by task components, to eliminate components, and/or to increase the attentional value of the discriminating features of the response topography. In relation to their application, guidelines are suggested about when they should be employed in conjunction with response prompts; when they should be used, either alone or in conjunction with response prompts, in preference to response prompts alone; whether one or a series of modifications is required; and at what point during teaching should probe trials on the unmodified task be introduced.     

2000只近视眼角膜表面形态及屈光参数的检测分析

目的 :探讨近视眼的角膜表面形态及屈光参数的变化规律。方法 :用电脑验光仪及计算机辅助的角膜地形图仪为 2 0 0 0只近视眼 (分为低度、中度、高度、超高度 4组 )行验光及角膜摄像分析。以 2 82只正视眼作对照组。结果 :低度、中度、高度及超高度组角膜表面形态近圆形 (圆形及椭圆形 )分别为 2 8.39% ,2 7.73% ,2 8.0 4 % ,2 0 .0 8% ,低于正视组的 4 1.6 8% (P<0 .0 5 ) ;领结形 (对称及非对称领结形 )分别为6 5 .5 1% ,6 5 .91% ,6 4.87% ,72 .32 % ,高于正视组的 5 2 .0 7% (P <0 .0 5 ) ;角膜表面规则指数 (SRI)明显高于正视组 ;角膜表面不规则指数 (SAI)与正视组差异无显著性 (P >0 .0 5 ) ;平均角膜屈光度 (ACP)和散光度(CYL)显著大于正视组 (P <0 .0 5 )。结论 :近视眼角膜表面形态及屈光参数较正视眼有明显变化。LASIK术前详细分析角膜地形图为设计个性化手术方案及预测疗效提供了重要依据。     

ABNORMAL CORNEAS MEASURED BY A NEW PHOTOGRAMMETRIC TECHNIQUE

The limitations of keratometry and photokeratoscopy are briefly discussed. A new photogrammetric technique of measuring corneal topography is described. Contours and cross-sections of abnormal corneas are presented to illustrate the scope and application of the new technique.     

Responses of human primary sensorimotor and supplementary motor areas to internally triggered unilateral and simultaneous bilateral one‐digit movements. A high‐resolution EEG study

We modelled the responses of human primary sensorimotor areas and supplementary motor area to simple, self-initiated unilateral and simultaneous bilateral middle finger movements using a novel high-resolution electroencephalography technology. The results support the view that these cortical motor areas are involved in parallel and present similar activity in the preparation, initiation, and execution of the contralateral and bilateral movements. Furthermore, the left primary sensorimotor area (dominant hemisphere) appears to be activated more than the right primary sensorimotor area during the preparation and performance of the ipsilateral movements.     

Normal and regenerating optic fibers in goldfish tectum: HRP-EM evidence for rapid synaptogenesis and optic fiber-fiber affinity

The distribution of normal and regenerating retinal fibers and synapses was studied on tectum in goldfish by light (LM) and electron microscopy (EM). Since labeling of the early regenerating fibers was previously reported to be difficult, a new 'cold-fill' HRP labeling protocol was developed, which labeled regenerating optic fibers and terminals on tectum as early as 14 days after nerve crush when they first arrive on tectum. In order to characterize the laminar distribution of optic afferents in normal fish and in fish regenerating for 14-240 days, EM photomontages of areas 14 microns wide by 160 microns deep through the HRP-labeled primary optic innervation layer (S-SO-SFGS) were constructed. The time points in regeneration that were examined spanned the period in which others have shown that an initially diffuse retinotopic map becomes spatially restricted. At the LM level regenerating optic fibers were restricted to the optic lamina. They reinnervated tectum in an anterior to posterior sequence as previously seen with autoradiography. In addition, at 14 days, some "pioneer" optic fascicles were found to have already grown to posterior tectum where they gave rise to branches with boutonlike terminations and growth-cone-like processes. Form the ultrastructural analysis it was clear that optic fibers and terminals observed strict laminar boundaries as they partitioned themselves in the optic laminae (S, SO and SFGS) in both normal and regenerating fish. The behavior of optic fibers was lamina specific with respect to synapse formation and the orientation of fiber outgrowth. As early as 14 days regeneration, optic fibers made synapses onto the four types of postsynaptic profiles observed in normal fish. Numerous optic terminals were labeled at 14 days, and there appeared to be no waiting period between fiber ingrowth to the SO and synapse formation in the S and SFGS. At 14-60 days, atypical synaptic contacts which appear to be nascent synapses were made by labeled optic fibers in fascicles and by growth-cone-like processes. By 21-30 days, the density of optic terminals was high and there were many more fasciculated optic fibers in the SFGS than normal as late as 350 days. These findings suggest that optic fiber lamination is highly constrained by tectal cues, that fibers rapidly regenerate many synaptic terminals before retinotopic map refinement is complete, and that fibers have a strong affinity for each other.