甲状腺疾病手术消毒前超声定位的临床应用

目的 探讨手术消毒前超声定位在甲状腺疾病的手术治疗中的临床实用价值.方法 对80例甲状腺多发结节患者,于手术消毒前由术者行超声定位,观测病灶个数、病灶于上下极分布情况以及距后包膜的距离;并对病灶手术切除率、手术探查时间、声嘶、低钙并发症发生率进行统计,与未行超声定位的80例甲状腺多发结节患者进行对照.结果 80例患者术中按超声所观测数据确定的位置均能迅速找到病灶,病灶切除率为93.75％(75/80),多发性结节患者能缩短探查时间,结节距离后包膜5 mm以上者无需费时显露保护喉返神经,仅70.00％(56/80)显露喉返神经.未使用超声定位组对5 mm以下位置非表浅结节,均只能留作随访,病灶切除率76.25％(61/80),对临床可疑恶性、探查无法触及者,仅能做大范围切除活检(同侧叶次全切除),喉返神经显露达92.50％(74/80).在手术探查时间、病灶切除率和喉返神经显露率方面两组间的差异有统计学意义(P＜0.01).两组中除1例因癌结节位于喉返神经入喉处术后出现声音略低外,均未发生严重并发症.结论 甲状腺疾病麻醉后消毒前超声定位,有助于了解甲状腺病灶的数量及与周围组织的三维关系,有利于术中迅速找到并准确切除病灶,是一种既能提高手术精确性、提高病灶切除率,又能降低手术难度的实用性很强的方法.     

曲面体层机侧位纵向体层程序在埋伏牙定位中的改良方法

目的 探讨曲面体层机中侧位纵向体层程序P21～23的投照技术及其在前牙区埋伏牙定位中的应用价值.方法 选取50例经曲面断层片或根尖片诊断为埋伏牙的患者,应用程序P21～23投照.分析埋伏牙的准确位置,并与埋伏牙拔除术中所见对比.结果 侧位纵向体层程序P21～23定位埋伏牙50例,其中偏唇侧13例,偏腭侧30例,居中7例,患牙的X线诊断与术中所见一致,准确率为100%.结论 侧位纵向体层程序P21～23是前牙区埋伏牙定位中更直接有效的方法 .     

全球健康领域政府对非政府组织的定位与合作——以世卫组织、美国和英国为例

非政府组织(NGO)在全球健康治理中发挥重要角色,已成为欧美发达国家和联合国系统全球健康战略的重要组成部分,联合国可持续发展目标也提出要强化NGO作为全球健康治理合作者的角色。本研究以全球健康战略比较成熟的世界卫生组织和美英两国为例,综述它们在全球健康战略中对NGO的定位和合作,为中国全球健康战略的制定以及与NGO的合作及定位提供参考建议。研究发现,世界卫生组织、美国和英国在其全球健康战略中均给予NGO明确定位,即加强相互合作,来扩大其在全球健康领域的影响力。因此,中国应将NGO纳入全球健康战略,建立NGO的管理和合作机制,使其成为全球健康的重要补充力量;严格筛选国际NGO进行合作,努力培育和支持本土NGO参与中国全球健康项目的实施;制定NGO合作清单和负面清单;同时加强监管和审核,规避NGO可能带来的风险。     

Grating acuity of the golden hamster

Summary Twelve golden hamsters learned visual discriminations in a Y-maze for a food reward. After initial training on a light/dark task, the hamsters learned to discriminate a grating from a uniform grey field of the same mean luminance as the grating; grating orientation was varied among hamsters. Those animals trained with the grating vertical or horizontal learned significantly faster than those trained on obliques. Acuity, measured by varying the spatial frequency of the grating according to the descending method of limits or the method of constant stimuli, was determined to be about 0.7 c/deg at 50% correct or 0.5 c/deg at 70% correct for all orientations tested (0 °, 45 °, 90 °, 135 °). Acuity was relatively constant within the human photopic range, but decreased to about 0.35 c/deg at 5 × 10^-4cd/m². The change in acuity as a function of luminance suggests that the hamster has a rod-dominated retina.     

Development of the kitten visual cortex depends on the relationship between the plane of eye movements and visual inputs

Summary 1. Previous experiments have demonstrated that eye movements, acting through the extraocular muscle (EOM) proprioceptive afferents, are necessary for the development of orientation selectivity in the cells of the kitten visual cortex. New experiments were carried out to study the effect of the plane of eye movements on the preferred orientation acquired by the visual cortical cells. 2. Darkreared (DR) kittens were operated on at 5–6 weeks of age. In the first series of experiments, 4 out of the 6 EOMs were removed bilaterally in such a way that both eyes could only move in a single plane, either vertical or horizontal. In the second series of experiments, the same operation was performed on one eye which was also sutured shut and, on the other side, the EOM were deafferented by intracranial section of the ophthalmic branch of Vth nerve and the eye left open. 3. 1–4 days after surgery the kittens were given 6 h of visual experience and 12 h later were prepared for visual cell recording in Area 17. 4. In kittens of the first series: orientation selectivity developed in the majority (60–65%) of visual cells, most of which encoded horizontal orientations when the eyes had moved in the vertical plane and vertical orientations when the eyes had moved in the horizontal plane. These results show that the plane of eye movements during early visual experience influences the distribution of preferred orientations with an orthogonal relation. Ocular dominance histograms were strabismic like. 5. In kittens of the second series: orientation selectivity developed in 40–50% of cells, about half of which were tuned for the orientation orthogonal to the direction of movement of the occluded eye, as in experiment I. The seeing, deafferented eye, presumably would have sent normal visual inputs centrally, corresponding to displacements on the retina in every direction since the ocular motility of that eye had not been disturbed. However, proprioceptive information about its movements was suppressed. As only some of the EOMs of the occluded eye were still present and connected, the conclusion is that the observed influence of the plane of eye movements acts through the proprioceptive afferents. The ocular dominance histograms showed: 1) a powerful change in favour of the seeing eye after only 6 h of monocular visual experience; 2) a larger effect of monocular visual experience in the hemisphere contralateral to the seeing eye; 3) a linkage between acquisition of orientation selectivity and shift in ocular dominance. 6. Our results suggest that normal development of orientation selectivity in visual cortical cells results from the close association of visual and EOM afferent inputs. It is suggested that these two signals must occur with a precise temporal relationship.     

铅对人红细胞在低粘切变流场中取向的影响

用新型激光衍射仪研究了铅对人红细胞在低粘切变流场中取向的影响，并观察了尼克酰胺的抗铅作用，结果表明，铅使人红细胞在Ｃ＝０轨道上取向的数目下降，且有明显的剂量－－效应关系，尼克酰胺有抗铅致人红细胞取向变化的作用。     

Characteristics of surround inhibition in cat area 17

 The effects of stimuli falling outside the ’classical receptive field’ and their influence on the orientation selectivity of cells in the cat primary visual cortex are still matters of debate. Here we examine the variety of effects of such peripheral stimuli on responses to stimuli limited to the receptive field. We first determined the extent of the classical receptive field by increasing the diameter of a circular patch of drifting grating until the response saturated or reached a maximum, and by decreasing the diameter of a circular mask in the middle of an extended grating, centred on the receptive field, until the cell just began to respond. These two estimates always agreed closely. We then presented an optimum grating of medium-to-high contrast filling the classical receptive field while stimulating the surround with a drifting grating that had the same parameters as the central stimulus but was varied in orientation. For all but five neurons (of 37 tested), surround stimulation produced clear suppression over some range of orientations, while none showed explicit facilitation under these conditions. For 11 cells (34% of those showing suppression), the magnitude of suppression did not vary consistently with the orientation of the surround stimulus. In the majority of cells, suppression was weakest for a surround grating oriented orthogonal to the cell’s optimum. Nine of these cells (28%) exhibited maximum inhibition at the optimum orientation for the receptive field itself, but for 12 cells (38%) there was apparent ’release’ from inhibition for surround gratings at or near the cell’s optimum orientation and direction, leaving inhibition either maximal at angles flanking the optimum (9 cells) or broadly distributed over the rest of the orientation range (3 cells). This implies the existence of a subliminal facilitatory mechanism, tightly tuned at or near the cell’s optimum orientation, extending outside the classical receptive field. For just two cells of 13 tested the preferred orientation for a central grating was clearly shifted towards the orientation of a surrounding grating tilted away from the cell’s optimum. The contrast gain for central stimulation at the optimal orientation was measured with and without a surround pattern. For nine of 25 cells tested, surround stimulation at the cell’s optimum orientation facilitated the response to a central grating of low contrast (≤0.1) but inhibited that to a higher-contrast central stimulus: the contrast-response gain is reduced but the threshold contrast is actually decreased by surround stimulation. Hence the receptive field is effectively larger for low-contrast than for high-contrast stimuli. Inhibition from the periphery is usually greatest at or around the cell’s optimum, while suppression within the receptive field has been shown to be largely non-selective for orientation. Inhibition by orientations flanking the optimum could serve to sharpen orientation selectivity in the presence of contextual stimuli and to enhance orientational contrast; and it may play a part in orientation contrast illusions. Received: 28 July 1996 / Accepted: 30 January 1997     

Contrast enhancement in a Hermann grid with variable figure-ground ratio

Summary Psychophysical experiments on contrast vision were made using a modified Hermann grid which was graded in two directions. This pattern was composed of intersecting (IG) and intersected stripes (ID) representing 15 shades of a gray scale, and was viewed against 5 uniform backgrounds (BGD) ranging from white to black. Illusory light and dark patches at intersections were essentially limited to IG's that ranged in reflectance between BGD and ID. The illusion was most distinct when the contrast ratio between IG and BGD was minimum, while that between IG and ID was maximum; it was much reduced on intersections formed by equireflectant stripes, such as those in the original Hermann grids. Brighter responses were evoked by a white BGD and darker responses by a black BGD. Gray BGD's elicited both kinds of responses. The contrast effects were more pronounced for vertical and horizontal than for diagonal grid orientation. An optimum grid was devised that shows maximum brightness changes at almost every intersection, even when fixated foveally. The observations are interpreted in terms of Baumgartner's receptive field hypothesis.This work was supported (in part) by PHS Grant EY00227 from the National Eye Institute (to Dr. C.L. Schepens) and by a grant from the John A. Hartford Foundation, Inc. (to Dr. H.L. Teuber).JL worked under the summer student program of Chelsea High School     

Prestimulus top-down reflection of obsessive-compulsive disorder in EEG frontal theta and occipital alpha oscillations

Sex differences are consistently reported in human navigation. Indeed, to orient themselves during navigation women are more likely to use landmark-based strategies and men Euclidean-based strategies. The difference could be due to selective social pressure, which fosters greater spatial ability in men, or biological factors. And the great variability of the results reported in the literature could be due to the experimental setting more than real differences in ability. In this study, navigational behaviour was assessed by means of a place-learning task in which a modified version of the Morris water maze for humans was used to evaluate sex differences. In using landmarks, sex differences emerged only during the learning phase. Although the men were faster than the women in locating the target position, the differences between the sexes disappeared in delayed recall.     

Properties of visual cortical cells of the intact and the deafferented hemisphere of unilateral optic tract sectioned acute and chronic adult cats

Summary Single unit recording from visual cortex areas 17 and 18 and in the border region between them was performed on adult cats with unilateral optic tract section (OTX) either on the day of the operation (acute) or three to six months postoperatively (chronic). Visual activity from both hemispheres was analyzed with respect to the responsiveness level, the ocular dominance distribution and selectivity to orientation and direction. The results showed almost a complete absence of visual responsiveness in the deafferented hemisphere and a considerable reduction of responsiveness in the intact hemisphere. Following surgery an increase in visually responsive cells was found in the intact hemisphere as postoperative recovery continued. In addition, a reduction in the proportion of cells selective for orientation and direction was also found in the intact hemisphere of the OTX animals as compared to the control cats. Furthermore, cortical binocularity was not affected in the intact hemisphere of all OTX cats.We conclude that an almost total absence of interhemispheric callosal transfer of visual functions from the intact to the deafferented hemisphere is induced as a result of the unilateral OTX in adult cats. Moreover, the fact that the absence of cortical binocularity in the hemisphere receiving direct geniculate input was not disrupted, indicates the absence of callosal transfer from the deafferented to the intact hemisphere.