Evidence for frequent divergence impairment in French dyslexic children: deficit of convergence relaxation or of divergence per se?

Aim There is a controversy as to whether dyslexic children present visuo-motor disabilities such as vergence and accommodative problems assessed with orthoptic tests. The purpose of this study is to re-examine this issue in a large population of children. Methods Extensive orthoptic evaluation was made in 57 dyslexic and 46 non-dyslexic (“normal”) age-matched children. Convergence and divergence capacities were evaluated at two distances (30 cm and 400 cm). Results Binocular vision measured with stereo-acuity tests was normal in dyslexics. In contrast, the near point of convergence was significantly more remote in dyslexics; most importantly, divergence at both far and near distance was significantly more reduced in dyslexics (median value 4 pD and 10 pD, respectively, at far and near) than in “normals” (median value 6 pD and 12 pD, at far and near). Conclusion The existence of the divergence deficit at far distance indicates the presence of deficit of divergence per se, independently from convergence and accommodation relaxation. This result is novel and corroborated by physiological studies indicating distinct control of convergence and divergence, both at the cortical and subcortical premotor level. We conclude that vergence deficits are frequently present in dyslexics, and that dyslexics should be re-educated; training should address distinctively convergence and divergence subsystems.     

实施归口管理对肺结核病人发现率和治愈率的影响分析

目的　探讨实施结核病归口管理对提高涂阳肺结核病人发现率和治愈率的影响。方法　对 1994年至2 0 0 0年 2 0个参加卫生部加强与促进结核病控制项目县的项目报表和年转归报表进行分析。结果　由于项目县实施了结核病归口管理 ,涂阳病人的发现率、治愈率明显高于未实施结核病归口管理的非项目县。结论　实施结核病归口管理是提高肺结核病人特别是具有传染性肺结核病人发现率和治愈率的有效措施     

Clinical and laboratory investigations of the relationship of accommodation and convergence function with refractive error

Studies of the relationship of clinical and laboratory measures of accommodation and convergence function with refractive error are reviewed. There are inconsistencies in results from study to study presumably due, in part, to methodological differences. However, some basic trends can be outlined. In studies in young adults, accommodation in darkness (dark focus), optical reflex accommodation, and proximally induced accommodation are less in myopes than in emmetropes and hyperopes. It also appears that nearpoint esophoria is associated with higher rates of myopia progression in children. Implications for myopia etiology are discussed.     

Convergence of subthalamic and striatal efferents at pallidal level in primates: an anterograde double-labeling study with biocytin and PHA-L

Small injections of two highly sensitive anterograde tracers, Phaseolus vulgaris-leucoagglutinin (PHA-L) and biocytin, into the striatum and the subthalamic nucleus of squirrel monkeys (Saimiri sciureus) have revealed a high degree of convergence of striatal and subthalamic fibers upon single pallidal cells. Both afferent systems formed highly complex band-like patterns that were largely in register with one another. At single cell level, the somata of pallidal neurons were closely surrounded by subthalamic terminal varicosities, whereas the dendrites were entwined mostly by striatal fibers. Typically, a subthalamopallidal fiber coursed in a caudorostral direction and arborized according to a uniform pattern along its trajectory in the pallidum. Numerous thin and markedly varicose axon collaterals detached themselves at right angle from the main subthalamopallidal fiber. These highly branched collaterals were mostly oriented along the mediolateral plane and entwined rather loosely the dendrites but surrounded very closely the somata of pallidal neurons. In contrast, a striatopallidal fiber travelled in a rostrocaudal direction. Its initial segment made only en passant contacts with pallidal cell bodies, whereas its distal end closely entwined the dendrites of pallidal neurons, forming arrangements similar to 'woolly' type fibers. These results suggest that a single subthalamic fiber may influence a rather large collection of pallidal neurons in a similar fashion, compared to the striatal input which appears to exert a more specific control upon selected sets of the same pallidal neurons.     

Saccular and utricular inputs to single vestibular neurons in cats

Saccular and utricular organs are essential for postural stability and gaze control. Although saccular and utricular inputs are known to terminate on vestibular neurons, few previous studies have precisely elucidated the origin of these inputs. We investigated the saccular and utricular inputs to single vestibular neurons in whole vestibular nuclei of decerebrated cats. Postsynaptic potentials were recorded from vestibular neurons after electrical stimulation of the saccular and utricular nerves. Ascending and descending axonal projections were examined by stimulating the oculomotor/trochlear nuclei and the cervical segment of the spinal cord, respectively. After each experiment, locations of recorded neurons were identified. The recorded neurons (140) were classified into vestibulo-spinal (79), vestibulo-oculo-spinal (9), and vestibulo-ocular (3) neurons based on antidromic responses; 49 other vestibular neurons were unidentified. The majority of recorded neurons were mainly located in the lateral vestibular nucleus. Most of the otolith-activated vestibular nuclei neurons seemed to participate in vestibulospinal reflexes. Of the total 140 neurons recorded, approximately one third (51) received saccular and utricular inputs (convergent neurons). The properties of these 51 convergent neurons were further investigated. Most (33/51) received excitatory postsynaptic potentials (EPSPs) after saccular and utricular nerve stimulation. These results implied that most of the convergent neurons in this study additively coded mixed information for vertical and horizontal linear acceleration. Based on the latencies of convergent neurons, we found that an early integration process for vertical and horizontal linear acceleration existed at the second-order level.     

Health services reforms: political and managerial aims--an international perspective

Health policy everywhere is in flux. In marked contrast with the impenetrable orthodoxy and inaction characteristic of past decades, health policy currently is in the midst of large-scale upheaval. Many of the fundamental assumptions and principles that long guided health-sector development are in the process of being turned upside down. Whether a country is rich or poor, it matters not. Virtually every country either has or is contemplating major reforms in its provisions for the organization and financing of health services. Moreover, the differences in health services structure which divided nations, are becoming smaller--to the point where formerly shunned international exchanges now are considered useful mediums for the exposition of common tensions and the exploration of choices for adapting health care to complex and new economic realities.     

集合不足型外斜视外直肌斜向后徙

目的　评价集合不足型外斜视外直肌斜向后徙的效果。方法　研究组 2 2例 ,对照组 8例 ,看近斜视角大于看远斜视角至少 15PD ,研究组 2 2例行外直肌斜向后徙术 ,对照组 8例行标准的外直肌后徙术。结果　研究组 18/2 2术后看近外斜度≤ 10PD ,2 2 /2 2术后看远外斜度≤ 10PD ,看近看远外斜角平均差值由术前 2 5± 8 11PD减少到术后 5 2 3± 4 0 3PD。对照组仅 3 /8术后看近外斜度≤10PD ,6/8术后看远外斜度≤ 10PD。结论　集合不足型外斜视外直肌斜向后徙术效果优于标准的外直肌后徙术。     

改良外斜视矫正术治疗儿童小度数集合不足型间歇性外斜视的临床观察

目的研究改良的外斜视矫正手术治疗儿童小度数集合不足型间歇性外斜视的手术疗效。方法 31例视近斜视度在20^△~30^△的集合不足型间歇性外斜视行改良的外斜视矫正手术,分别观察手术前后视远和视近的斜视度、视远和视近的斜视度的差值、术后的正位率、A-V型斜视、眼球运动以及立体视的变化。随访时间6~12个月。结果术后视近和视远的斜视度平均比较(t=8.72,P<0.05)和(t=3.46,P<0.05),视远和视近的斜视度的差值比较(t=5.75,P<0.05),平均立体视锐度为361.2"(t=3.25,P<0.05),正位率83.9%(26/31),术后没有出现A-V型斜视和眼球运动受限。结论对于小度数集合不足型间歇性外斜视,改良的外斜视矫正手术在减小视远和视近的斜视度,降低视远和视近的斜视度的差值,恢复立体视,提高术后的正位率均安全有效。