Development of the retinal pathway to the pretectum of the cat

The development of retinal projections to the pretectal complex of prenatal and early postnatal cats has been examined using the anterograde transport of horseradish peroxidase and tritiated amino acids. As early as embryonic day 38, the entire dorsal pretectum is penetrated by retinal ganglion cell axons. At this stage the bilateral complement of retinal efferents appears to be dispersed uniformly within the pretectal anlage. A week later, on embryonic day 46, indistinct foci of peroxidase reaction product can be discerned within 2 of the primordial nuclei: the nucleus of the optic tract and the olivary nucleus. By embryonic day 56, five distinct bilateral fields of retinal fiber termination are apparent within the following regions:

(i) the nucleus of the optic tract;

(ii) the pretectal olivary nucleus;

(iii) the posterior pretectal nucleus;

(iv) the anterior pretectal nucleus; and

(v) the medial pretectal nucleus. Four days before birth, on embryonic day 61, crossed and uncrossed retinal arbors are partially segregated within the nucleus of the optic tract and the pretectal olivary nucleus.

The early postnatal retinal connection to the pretectum has an overall pattern virtually indistinguishable from that of the mature cat. The ontogeny of the retinal influx to the pretectum is similar to that of the retinocollicular projection.⁶¹ However, the development of retinal projections to the pretectum and superior colliculus appears to lag behind those to the dorsal lateral geniculate nucleus.⁴⁹ These differences may reflect temporal and spatial gradients in the maturation of three major classes of retinal ganglion cells.     

胸腰段后髓动脉的起源及其临床意义

目的:为选择性脊髓血管造影和椎管内显微外科提供解剖学资料。方法:采用尸体标本30例,于节段性动脉内逐一注入红色乳胶,在完整脊髓上解剖观察。结果:每例脊髓胸腰段的后髓动脉数目5～13支,平均8.4支。后髓动脉起始情况分3型10亚型,其中后髓动脉与前髓动脉由同一肋间后动脉发出仅34支(13.5％)。胸下部及腰部后髓动脉呈典型“发卡”样折曲。后髓动脉平均外径0.37±0.12mm。约1/3标本在T_(11)～L_3间有1支后髓动脉较粗(>0.5mm),它是脊髓后下部血供的主要来源。结论:多数后髓动脉单独起始,较大的后髓动脉应引起注意。     

前路椎体次全切在治疗颈椎后纵韧带骨化中的应用

目的：探讨颈前路椎体次全切治疗颈椎后纵韧带骨化的手术减压范围。方法：采用前路椎体次全切植骨融合术治疗颈椎后纵韧带骨化56例，其中完全切除骨化者47例，用“漂浮法”处理者9例，并针对不同个体及病变特点采用不同的减压范围。结果：54例获得3个月-6a随访，平均28个月。植骨均于术后3-5个月内获得骨性融合。JOA评分由术前8．5分提高到术后14．1，平均改善率74％，优良率80．2％。结论：行椎体次全切术治疗颈椎后纵韧带骨化时应针对不同个体及病变特点采用不同的足够的减压范围，可以减少并发症，并获得较佳的疗效。     

后鼓室颞骨切片与CT对照研究

目的：为后鼓室及耳科病变的影像诊断和手术治疗提供解剖学基础。方法：l5例成人头部标本，以眦耳线（cML）为基线，获得间隔为1．00mm，厚度为1．00mm的CT图像，扫描后的头部标本按原定位截取以耳颞区为中心的组织块并将其制成厚为1．00mm的连续横断薄层切片。标本切片与CT图像对照，对颞骨内砧骨窝、鼓索隆起、茎突隆起、面神经隐窝、鼓室窦、岬小桥、外耳道上棘等结构进行观察。结果：砧骨窝深度为1．49mm，至面神经锥曲的距离为5．67mm。后鼓室窦内侧壁至面神经水平部的距离为3．14mm。外耳道上棘至面神经垂直段、鼓索神经、鼓岬的距离分别为16．76mm、15．94mm和21．81mm。结论：耳颞区断面标本与CT图像进行对照研究，其结果对耳科疾病的影像诊断及手术治疗具有参考价值。     

The laminar distribution of cortical connections with the tecto- and cortico-recipient zones in the cat's lateral posterior nucleus

The anterograde and retrograde transport of wheat germ agglutinin congugated to horseradish peroxidase was used to examine the laminar organization of cortical connections with the two visual zones that comprise the cat's lateral posterior nucleus. Microelectrophoretic deposits of the tracer into the principal tecto-recipient zone in the medial division of the lateral posterior nucleus revealed reciprocal connections with the following cortical fields: areas 19 and 21a, the medial and lateral banks of the middle suprasylvian sulcus, and the dorsal and ventral banks of the lateral suprasylvian sulcus, which correspond to the dorsal lateral suprasylvian and ventral lateral suprasylvian visual areas of Palmer et al. [(1978) Brain Res. 177, 237-256] and an area in the fundus of the posterior suprasylvian sulcus. In each of these cortical areas two distinct populations of cells were labeled, small pyramidal neurons in layer VI and large pyramidal cells in layer V. Overlying these backfilled cells were two bands of anterograde label, a narrow strip in layer I and a wide band centered in layer IV. Deposits of wheat germ agglutinin conjugated to horseradish peroxidase confined to the striate-recipient zone in the lateral portion of the lateral posterior nucleus resulted in cortical label in areas 17, 18, 19, 20a and b, 21a, the medial and lateral banks of the middle suprasylvian sulcus, the posterior suprasylvian sulcus and in the fundus of the splenial sulcus. In all cortical areas other than 17 and 18, the laminar distribution of label was the same as that found after deposits of the tracer into the medial division of the lateral posterior nucleus. In contrast, areas 17 and 18 contained backfilled cells that were confined to layer V and anterograde label that was restricted to layer I. These findings indicate that the cortical areas that receive a direct projection from the A laminae of the dorsal lateral geniculate nucleus maintain a distinct laminar organization of reciprocal connections with the extrageniculate visual thalamus. Conversely, all other visual areas of the cortex share a common pattern of reciprocal connections with both the tecto- and striate-recipient zones of the lateral posterior nucleus.     

Influence of the superior colliculus on visual responses of cells in the rabbit's lateral posterior nucleus

Summary The lateral posterior-pulvinar (LP-P) complex of mammals receives a major input from the superior colliculus (SC). We have studied the response properties of LP cells and investigated the effects of reversible inactivation of the colliculus on the visual responses of LP units in anesthetized and paralyzed rabbits. Cells in LP had large receptive fields responsive to either stationary or moving stimuli. One third of the motion-sensitive cells were direction selective. The size of the receptive fields increased with eccentricity and there was a retinotopic organization along the dorso-ventral axis. Comparison of the LP and superior colliculus properties revealed substantial differences in visual response characteristics of these two structures such as the size of the receptive fields and the number of direction-selective cells. Electrical stimulation of the LP evoked antidromic action potentials in tectal cells that were motion sensitive. We found a dorsoventral gradient in the projections of collicular cells. Units located more dorsally in the colliculus sent their axons to LP while cells lying more ventrally sent axons toward the region lying posterior to LP. A micropipette filled with lidocaine hydrochloride was lowered into the superficial layers of the superior colliculus in order to reversibly inactivate a small population of collicular cells. Rendering the superior colliculus inactive produced a sharp attenuation of visual responses in the majority of LP cells. Some neurons ceased all stimulus-driven activity after collicular blockade while a few cells exhibited increased excitability following collicular inactivation. These experiments also indicate that the tecto-LP path is topographically organized. An injection in the colliculus failed to influence the thalamic response when it was not in retinotopic register with the LP cells being recorded. Our results demonstrate that the superior colliculus input to LP is mainly excitatory in nature.     

电刺激杏仁核对猫丘脑后核内脏大神经诱发放电的抑制作用

本文使用条件—检验刺激技术,研究了电刺激杏仁皮质内侧核对猫丘脑后核内脏大神经诱发放电的影响。电刺激杏仁皮质内侧核抑制丘脑后核的中等和长潜伏期内脏大神经诱发放电呈现两种形式:即时抑制和迟发抑制。前者可能是通过从杏仁核到丘脑后核的神经通路产生的,静脉注射纳洛酮可消除这种抑制,提示有鸦片样物质的参与。后者可能涉及神经—体液性因素。结果提示,杏仁核参与抑制内脏痛。     

准分子激光屈光性角膜切削术治疗近视和近视散光3年疗效分析

目的 :评价准分子激光角膜切削术 (photorefoactivekeratecomy ,PRK)治疗近视、近视散光的远期疗效。方法 :按术前屈光度将 2 0 9例 (3 77例 )屈光度为 - 1 5 0～ 1 6 0D的患者分为二组 ,低中度组 (I组 )为 - 1 5 0～ - 6 0 0D(2 3 8眼 ) ,高度组 (II组 )为 - 6 2 5～ - 1 6 0 0D(1 3 9眼 )。应用美国Visx2 0 /2 0准分子激光仪对上述二组患者行PRK治疗 ,并对患者术后 3年的屈光度、视力、角膜屈光力、角膜厚度、并发症进行随访观察。结果 :I组、II组中屈光度 <± 1D者分别占 94 5 %和 6 1 9% ;≥± 2 0 0D分别占 0 % ,2 3 7%。术后裸眼视力≥ 0 5者在I组、II组中分别占 99 6 %和 79 9% ;≥ 1 0者分别占 85 3 % ,48 2 %。角膜屈光力两组均在术后 6个月稳定 ,角膜上皮下雾状混浊O级在I组、II组分别为1 0 0 %和 98 6 % ,术后眼压两组均正常。结论 :准分子激光屈光性角膜切削术治疗近视、近视散光效果肯定 ,尤对低中度患者疗效更佳     

侧块钢板螺钉系统在颈椎后路手术中的应用

目的 探讨侧块钢板螺钉系统在颈椎后路手术中应用的临床经验。方法 对1999年2月－2000年3月间共36例行侧块钢板内固定的患者进行回顾分析。29例（80．6％）获得随访,平均随访时间8个月（4－15个月）。29例患者中颈椎病（3节及3节段以上椎间盘突出）20例,黄韧带骨化症（OYL）1例,后纵韧带骨化症（OPLL）2例,颈椎骨折脱位6例。手术时采取坐位,病变节段行全椎板切除减压,保留关节突。钢板螺钉固定于侧块（即关节突）,同时关节突间植骨融合。结果 29例患者共植入124枚螺钉,平均每位患者4．3枚。颈痛明显改善者为18例（20例术前存在颈痛）占90％。术后3－6月X线随访,27例患者关节突间见骨小梁生成,融合率93％。4例患者路侧块钢板螺钉系统能提供较稳定的固定,有效改善颈痛。钢板螺钉松动与神经根损伤是较严重的并发症。只要严格掌握手术适应证与安装技术,颈椎后路钢板固定是治疗颈椎不稳的一种十分有效的方法。     

Effects of Posterior Tibial Slope on a Posterior Cruciate Retaining Total Knee Arthroplasty Kinematics and Kinetics

BackgroundIt has been hypothesized that increasing posterior tibial slope can influence condylar rollback and play a role in increasing knee flexion. However, the effects of tibial slope on knee kinematics are not well studied. The objective of this study is to assess the effects of tibial slope on femorotibial kinematics and kinetics for a posterior cruciate retaining total knee arthroplasty design.MethodsA validated forward solution model of the knee was implemented to predict the femorotibial biomechanics of a posterior cruciate retaining total knee arthroplasty with varied posterior slopes of 0°-8° at 2° intervals. All analyses were conducted on a weight-bearing deep knee bend activity.ResultsIncreasing the tibial slope shifted the femoral component posteriorly at full extension but decreased the overall femoral rollback throughout flexion. With no tibial slope, the lateral condyle contacted the polyethylene 6 mm posterior of the midline, but as the slope increased to 8°, the femur shifted an extra 5 mm, to 11 mm posterior of the tibial midline. Similar shifts were observed for the medial condyle, ranging from 7 mm posterior to 13 mm posterior, respectively. Increasing posterior slope decreased the posterior cruciate ligament tension and femorotibial contact force.ConclusionThe results of this study revealed that, although increasing the tibial slope shifted the femur posteriorly at full extension and maximum flexion, it reduced the amount of femoral rollback. Despite the lack of rollback, a more posterior location of condyles suggests lower chances of bearing impingement of the posterior femur and may explain why increasing slope may lead to higher knee flexion.