生长棒撑开术中经颅刺激运动诱发电位和体感诱发电位监测的应用价值

目的:分析生长棒撑开术中经颅刺激运动诱发电位(MEP)和体感诱发电位(SEP)神经功能监测的应用价值。方法:回顾性分析2010年10月~2015年1月我院进行的65例141次生长棒撑开手术,在生长棒撑开术中,运用MEP和SEP进行神经功能监测。MEP监测采用经颅刺激C3、C4,记录外周肌源性MEP,SEP监测采用刺激双侧胫后神经,记录电极采用Cz-CPz。阳性诊断标准:与基线相比,MEP波幅下降75%,SEP波幅下降50%或潜伏期延长10%。结果:141例次撑开手术中成功获得具有监护价值且重复性较好MEP 139例次,检出率98.6%,全程失败2例次(占1.4%);SEP成功监测140例次,检出率99.3%,失败1例(占0.7%)。所有患者均能成功记录到一种以上的诱发电位。本组141例次手术中未出现MEP及SEP监测阳性。所有患儿术后神经系统检查均无异常发现,神经功能监测结果均为真阴性。结论:生长棒撑开术是简单安全的手术操作,但是,运用MEP和SEP进行术中神经功能监测可以为生长棒撑开术提供客观的安全评估指标。     

Identification of a cone bipolar cell in cat retina which has input from both rod and cone photoreceptors

It has been generally accepted that rod photoreceptor cells in the mammalian retina make synaptic contact with only a single population of rod bipolar cells, whereas cone photoreceptors contact a variety of cone bipolar cells. This assumption has been challenged in rodents by reports of a type of cone bipolar cell which receives input from both rods and cones. Questions remained as to whether similar pathways are present in other mammals. We have used an antiserum against the glutamate transporter GLT1-B to visualize a population of cone bipolar cells in the cat retina which make flat contacts with axon terminals of both rod and cone photoreceptor cells. These cells are identified as OFF-cone bipolar cells and correspond morphologically to type cb1 (CBa2) cone bipolar cells which are a major source of input to OFF-beta ganglion cells in the cat retina. The GLT1-B transporter was also localized to processes making flat contacts with photoreceptor terminals in rat and rabbit retinas. Examination of tissue processed for the GluR1 glutamate receptor subunit showed that cb1 cone bipolar cells, like their rodent counterparts, express this alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-selective receptor at their contacts with rod spherules. Thus, a direct excitatory pathway from rod photoreceptors to OFF-cone bipolar cells appears to be a common feature of mammalian retinas.     

Glutamate receptors at bipolar synapses in the inner plexiform layer of primate retina: light microscopic analysis

At least 10 different types of bipolar cells have been distinguished in the primate retina. The axon terminals of these cells stratify in distinct strata in the inner plexiform layer and are involved in parallel pathways to distinct types of ganglion cells. Ionotropic glutamate receptor (GluR) subunits also show a stratified distribution in the inner plexiform layer. Here, we investigated whether different types of bipolar cells are associated with different types of ionotropic glutamate receptors in the inner retina of a New World primate, the common marmoset Callithrix jacchus. Vertical cryostat sections through central retina were double labeled with immunohistochemical markers for bipolar cell types and with antibodies to alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptor subunits GluR1 to 4, kainate receptor subunits GluR6/7, and the NR1C2' subunit of the N-methyl-D-aspartate (NMDA) receptor. The axon terminals of bipolar cell types were reconstructed from confocal sections, and the colocalized immunoreactive puncta were quantified. For all bipolar cell types, immunoreactive puncta for the AMPA receptor subunits GluR2, 2/3, and 4 were colocalized at highest densities, whereas GluR1-immunoreactive puncta were expressed at very low densities. The kainate receptor subunits GluR6/7 were predominantly associated with diffuse bipolar (DB6) and rod bipolar cells. The NMDA receptor subunit NR1C2' was specifically colocalized with flat midget and DB3 axons. These findings suggest that rod and cone bipolar cell types contribute to multiple but distinct glutamate receptor pathways in primate retina.     

Distribution of two splice variants of the glutamate transporter GLT-1 in the developing rat retina

The distributions of a carboxyl terminal splice variant of the glutamate transporter GLT-1, referred to as GLT-1B, and the carboxyl terminus of the originally described variant of GLT-1, referred to hereafter as GLT-1 alpha, were examined using specific antisera. GLT-1B was present in the retina at very early developmental stages. Labelling was demonstrable at embryonic day 14, and strong labelling was evident by embryonic day 18. Such labelling was initially restricted to populations of cone photoreceptors, the processes of which extended through the entire thickness of the retina and appeared to make contact with the retinal ganglion cells. During postnatal development the GLT-1B-positive photoreceptor processes retracted to form the outer plexiform layer, and around postnatal day 7, GLT-1B-immunoreactive bipolar cells appeared. The pattern of labelling of bipolar cell processes within the inner plexiform layer changed during postnatal development. Two strata of strongly immunoreactive terminals were initially evident in the inner plexiform layer, but by adulthood these two bands were no longer evident and labelling was restricted to the somata and processes (but not synaptic terminals) of the bipolar cells, as well as the somata, processes, and terminals of cone photoreceptors. By contrast, GLT-1 alpha appeared late in postnatal development and was restricted mainly to a population of amacrine cells, although transient labelling was also associated with punctate elements in the outer plexiform layer, which may represent photoreceptor terminals.     

Lateral mass screw–rod fixation of the cervical spine: a prospective clinical series with 1-year follow-up

BACKGROUND CONTEXT: Lateral mass plating has become the technique of choice for posterior cervical fixation. Although these systems are safe and reliable, they can be difficult to use in patients with abnormal cervical anatomy; screw placement can be compromised by the fixed hole spacing of the plate; screw back-out and other forms of implant failure can occur; and extension across the cervicothoracic junction can be problematic. PURPOSE: To report a series of patients undergoing posterior cervical stabilization with a polyaxial screw-rod construct and to investigate whether this new system offers any advantages over existing methods of fixation. STUDY DESIGN: A prospective study evaluating clinical and radiographic parameters in a consecutive series of patients treated with this technique. PATIENT SAMPLE: There were 21 patients in the study group. The surgical indication was cervical spondylosis in 14, trauma in 2, postsurgical kyphosis in 2 and 1 case each of congenital cervicothoracic stenosis, C7-T1 pseudarthrosis and basilar invagination with brainstem compression. OUTCOME MEASURES: Clinical indicators included age, gender, neurologic status, surgical indication and number of levels stabilized. Note was made of whether laminectomy and concomitant anterior reconstructive surgery were performed. Radiographic indicators included early postoperative computed tomography (CT) scan to check for screw placement and plain radiographs at subsequent visits. METHODS: The participants in this study underwent posterior cervical stabilization using lateral mass screw-rod fixation. Clinical and radiographic assessment was carried out immediately after surgery, and 3, 6 and 12 months after surgery. One-year follow-up was obtained in all cases. RESULTS: A total of 212 screws were implanted in 21 patients. Fixation was carried out over an average of 5.5 spinal segments (range, 2 to 11). The system was successfully implanted in all patients despite the presence of coronal and sagittal plane deformities and/or lateral mass abnormalities in the majority of cases. This system allowed for screw placement in the occiput, C1 lateral mass, C2 pars, C3-C7 lateral masses and upper thoracic pedicles. Early postoperative CT scanning confirmed satisfactory screw placement in all cases. Three patients experienced transient single-level radiculopathy, for an incidence of 1.4% per screw placed. Two patients developed wound seromas requiring evacuation. There were no infections or other wound healing problems. There were no examples of cord or vertebral artery injury, cerebrospinal fluid leak, screw malposition or back-out, loss of alignment or implant failure. When compared with plating techniques, screw-rod fixation appeared to offer several advantages. First, unlike plates, rods proved to be amenable to multiplanar contouring, which is often needed for deformities associated with cervical spondylosis. Second, lateral mass screw placement was more precise because it was not constrained by the hole spacing of the plate. Third, screw back-out and other types of implant failure were not seen. Fourth, the screw-rod system was more easily extended to the occiput and across the cervicothoracic junction. Fifth, the screw-rod system permitted the application of compression, distraction and reduction forces within the construct, to a greater extent than plate systems. The incidence of postoperative radiculopathy was similar to that seen with plate systems. CONCLUSIONS: These data indicate that posterior cervical stabilization with polyaxial screw-rod fixation is a safe, straightforward technique that appears to offer some advantages over existing methods of fixation. Results appear to be durable at 1-year follow-up. Benefits are more significant with longer constructs, especially those extending to the occiput or crossing the cervicothoracic junction.     

两种改良型Harrington棒的应力分析

作者对Ｈａｒｒｉｎｇｔｏｎ棒加Ｅｄｗａｒｄｓ套棒（ＨＲＳ）和Ｃ型Ｈａｒｒｉｎｇｔｏｎ棒（ＨＲＣ）两种改良型Ｈａｒｒｉｎｇｔｏｎ棒进行应力分析，确定出棒体的危险截面和危险点，通过理论分析和光弹模型试验表明：在受伤脊柱复位程度相同的条件下，ＨＲＣ棒在棘齿根部的应力明显低于ＨＲＳ棒。从而提示临床，采用ＨＲＣ棒治疗脊柱压缩性骨折，在获得与ＨＲＳ棒相同的复位效果时，可减少Ｈａｒｒｉｎｇｔｏｎ棒从棘齿根部断棒     

Soluble proteins of intact bovine rod cell outer segments.

Centrifugation of a particulate fraction from homogenates of bovine retinas to isopycnic equilibrium on sucrose density gradients yielded two discrete bands of particles containing rhodopsin (rod outer segments). The band having the lower buoyant density appeared on microscopic examination to be isolated discs and fragments of outer segments and contained little protein other than rhodopsin. The band having a higher buoyant density appeared to be outer segments with intact plasma membranes and exhibited osmotic properties different from those of the disrupted outer segments. The intact outer segments were shown by gel electrophoresis to contain five major polypeptide species other than rhodopsin, amounting to about 30% of the total protein. These polypeptides did not separate from the rhodopsin of the intact outer segments during isopycnic or zone sedimentation in isotonic or hypertonic media, but could be extracted by hypotonic solutions, in which they remained soluble under conditions where all the rhodopsin-containing membranes were sedimented. The extracted proteins all sedimented at less than 30 S, and are regarded as soluble proteins contained within an osmotic compartment of intact outer segments. Three of the five polypeptides of these soluble proteins were found in only trace quantities among the soluble proteins prepared from the retina as a whole or from other particulate fractions; these proteins may be peculiar to the rod cell or its outer segment. The remaining two species were more widely distributed.     

Small bowel perforation from unit rod posterior spinal fusion

An unusual complication of bowel perforation after unit rod posterior spinal fusion and anterior spine release via a retroperitoneal approach is described. This complication has not been previously described. The pediatric surgical specialist should be aware of this consideration in the differential diagnosis of abdominal pain after unit rod posterior spinal fusion.     

Optimal discrimination of an Abyssinian cat recessive retinal degeneration: a short electroretinogram protocol is more efficient than a long one

AIM: To determine the diagnostic efficiency of scores in a long protocol ectroretinogram (ERG) for Abyssinian cat slow recessive rod/cone dystrophy. METHODS: Kittens (n = 22) were bred from homozygous,affected and heterozygous normals. Ophthalmoscopy was regularly performed and disease signs noted. Cats (age > or = 8 months, 40 sessions, 1-3 repeats) were dark-adapted overnight, anaesthetized and simultaneous binocular ERG recorded using a long protocol. Conventional a- and b-amplitudes and peak implicit times were measured and b/a ratios calculated, initially only for ERG to the maximum photopic and scotopic stimulus. Principal components factor analysis was applied to various subsets of these scores plus age at testing. RESULTS: Six cats with ophthalmoscopic change were classed as affected. Three cats, one tested three times, were suspect. The rest were considered normal. The first analysis, of 80 eyes and 37 parameters, showed that the first factor was the only effective one. Using it, the groups overlapped 5%, scotopic amplitudes and b/a ratios loaded higher than peak times, the eyes were very similar, and age and photopic b/a ratios loaded poorly. The groups were discriminable with all the data. A second analysis, with eyes averaged and the 20 measures loading over 0.5 on the first factor, showed better group separation on factor I alone. An iterative search with varying data sets found that factor I was optimal, with eight ERG measures to the three brightest scotopic and one brightest photopic response. It produced a large absolute separation and classified the suspects consistently. With b/a ratios on these four ERG also included, 12 parameters gave better separation. CONCLUSION: Twelve scores on four ERG separate affected from normal cats with a wide gap and consistently classify suspects. It may work for earlier ages. Additional data probably adds noise. This combination of optimal scores needs confirmation in new data.