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31.
The purpose of this study was to investigate the possible effects of a treadmill training program on regeneration in young (3-month-old) and mature (13-month-old) rats with sciatic nerve crush using functional, electrophysiological, and morphometric analyses. When compared to both the young and mature untrained injury groups, those groups that underwent a treadmill training showed improved sensorimotor function evaluated by narrow beam test (p < 0.04 and p < 0.001, respectively), while muscle action potential amplitude was only greater in the young group (p < 0.02). The treadmill training program was able to reduce myelinated fiber density in the young group (p < 0.001), which appeared to increase after nerve injury (poly-innervation), but decreased with training, which means that the innervation became more functional. The data indicate that treadmill training is able to promote functional, electrophysiological and morphological recovery in young animals. However, in mature animals, improvement was only seen in terms of functional recovery.  相似文献   
32.
Cerebral palsy (CP) is a complex disorder of locomotion, posture and movements resulting from pre-, peri- or postnatal damage to the developing brain. In a previous study (Strata, F., Coq, J.O., Byl, N.N., Merzenich, M.M., 2004. Comparison between sensorimotor restriction and anoxia on gait and motor cortex organization: implications for a rodent model of cerebral palsy. Neuroscience 129, 141-156.), CP-like movement disorders were more reliably reproduced in rats by hind limb sensorimotor restriction (disuse) during development rather than perinatal asphyxia (PA). To gain new insights into the underpinning mechanisms of CP symptoms we investigated the long-term effects of PA and disuse on the hind limb musculoskeletal histology and topographical organization in the primary somatosensory cortex (S1) of adult rats. Developmental disuse (i.e. hind limb immobilization) associated with PA induced muscle fiber atrophy, extracellular matrix changes in the muscle, and mild to moderate ankle and knee joint degeneration at levels greater than disuse alone. Sensorimotor restricted rats with or without PA exhibited a topographical disorganization of the S1 cortical hind limb representation with abnormally large, multiple and overlapping receptive fields. This disorganization was enhanced when disuse and PA were associated. Altered cortical neuronal properties included increased cortical responsiveness and a decrease in neuronal selectivity to afferent inputs. These data support previous observations that asphyxia per se can generate the substrate for peripheral tissue and brain damage, which are worsened by aberrant sensorimotor experience during maturation, and could explain the disabling movement disorders observed in children with CP.  相似文献   
33.
The fundamental goal of skull base surgery is tumor removal with preservation of neurological function. Injury to the lower cranial nerves (LCN; CN 9–12) profoundly affects a patient’s quality of life. Although intraoperative cranial nerve monitoring (IOM) is widely practiced for other cranial nerves, literature addressing the LCN is scant. We examined the utility of IOM of the LCN in a large patient series. One hundred twelve patients underwent 123 skull base operations with IOM between January 1994 to December 1999. The vagus nerve (n = 37), spinal accessory nerve (n = 118), and the hypoglossal nerve (n = 83) were monitored intraoperatively. Electromyography (EMG) and compound muscle action potentials (CMAP) were recorded from the relevant muscles after electrical stimulation. This data was evaluated retrospectively. Patients who underwent IOM tended to have larger tumors with more intricate involvement of the lower cranial nerves. Worsening of preoperative lower cranial nerve function was seen in the monitored and unmonitored groups. With the use of IOM in the high risk group, LCN injury was reduced to a rate equivalent to that of the lower risk group (p > 0.05). The immediate feedback obtained with IOM may prevent injury to the LCN due to surgical manipulation. It can also help identify the course of a nerve in patients with severely distorted anatomy. These factors may facilitate gross total tumor resection with cranial nerve preservation. The incidence of high false positive and negative CMAP and the variability in CMAP amplitude and threshold can vary depending on individual and technical factors.  相似文献   
34.
The electrophysiological integrity of the adult rat spinal cord was assessed at the lumbar, lower cervical and cortical levels after the animals sustained a severe contusion injury at the mid-thoracic level (T8) and received either carbon filament cultured with fetal spinal cord tissue implants, fetal tissue implants, or carbon filament implants alone. Somatosensory evoked potentials (SSEPs) and motor evoked potentials (MEPs) were recorded from all animal groups at the end of the 8-week survival period. The results of this study demonstrate that the spinal cord injured animals that received carbon filament cultured with fetal spinal cord tissue implants had the highest degree of electrophysiological recovery, indicating that this combination plays an important role in promoting recovery after injury.  相似文献   
35.
Previous studies have shown that neonatal electrolytic lesions of basal forebrain cholinergic projections in mice lead to a transient cholinergic depletion of neocortex and to permanent alterations in cortical cytoarchitecture and in cognitive performance. The present study examines whether neonatal electrolytic lesions of the basal forebrain modify neocortical plasticity. Using cytochrome oxidase histochemistry, we compared cross-sectional areas of individual barrels in the barrel field of four groups of postnatal day 8 (P8) old mice that on P1 received either (1) right electrolytic lesions of the basal forebrain, (2) left C row 1-4 whisker follicle ablations, (3) combined lesion treatments or (4) ice anesthesia only. The size of barrels in basal forebrain lesioned animals was not significantly different from controls. However, the plastic response to whisker removal was compromised in basal forebrain lesioned animals. An index of plasticity, the ratio of row D/row C areas, was reduced significantly in the combined nBM lesioned/follicle ablation group. Compared to whisker-lesioned mice, the expansion in rows B and D and the shrinkage in the lesioned row C area were diminished in the combined treatment group. The present findings correspond to those from a study of rats injected with a cholinergic immunotoxin [Cereb. Cortex 8 (1998) 63]. These results suggest that cholinergic inputs play a role in regulating plasticity as well as in the morphogenesis of mouse sensory-motor cortex.  相似文献   
36.
目的:总结阵发性房颤病人肺静脉和/或上腔静脉肌的电生理标测和导管射频消融电隔离的结果,评价国人大静脉肌袖和心房的电连接类型和特点。资料与方法:顽固性阵发性房颤患者45例,在环状标测电极指导下行大静脉肌袖的电位记录、分析以及对能标测到袖电位的大静脉进行开口部的点或段的消融电隔离治疗。根据窦律和心房起搏下的肌袖内环形电极标测到的袖电位的激动顺序以及有效放电对袖电位的影响,总结和分析袖房之间的电连接特点。结果:共标测和/或电隔离肌袖115根,其中肺静脉100根,上腔静脉15根。其中呈单束状电连接43根(38%),双束状电连接54根(46%),多束状电连接12根(10%),环状电连接3根,无电连接3根。结论:根据环状电极标测到的袖电位的激动顺序和对放电的反应,提示袖房之间电连接的类型多为单束状和双束状(84%),说明对于大多数肌袖并不需要行环状消融,而只要在袖房连接处行点或节段性消融即可达到完全袖房电隔离的结果。  相似文献   
37.
BACKGROUND: Right ventricular apical (RVA) pacing induces electrophysiological and structural remodeling. Cardiac memory (CM) evolves during the course of pacing and is readily apparent on electrocardiography (ECG) or vectorcardiography (VCG) when normal ventricular activation resumes. OBJECTIVE: This study sought to assess ventricular repolarization (VR) changes during pacing and intermittent normal ventricular conduction by ECG and VCG and to determine the temporal and conformational evolution of CM. METHODS: Twenty sick sinus patients received a dual-chamber rate-adaptive (DDD-R) pacemaker and were paced from the RVA endocardium. The pacemakers were programmed to a short AV delay to maximize ventricular preexcitation. The ECG and VCG were recorded before and 1 day after implantation, and then daily for the first week (n=6) or weekly for 5 to 8 weeks (n=14), with the pacemakers temporarily programmed to AAI (normal ventricular activation). RESULTS: The first parameters to change were T-vector amplitude, T(area), and T(peak)-T(end) (T(p-e)), which decreased within 1 day after initiating pacing. CM became apparent between day 1 and day 3, was fully established after 1 week, and then remained stable. Signs of increased VR heterogeneity were observed as the T loop became more circular (decreased T(egenv)) and distorted (increased T(avplan)), which have previously been observed in conditions with increased risk for arrhythmias. Over weeks, VR duration was prolonged (increased QTc). In contrast, during ventricular pacing, a gradual shortening of the repolarization time was observed, suggesting a stabilizing adaptive process. CONCLUSION: In sick sinus syndrome patients in whom ventricular pacing is indicated, switching between normal AV conduction and ventricular pacing should be minimized to avoid periods of repolarization instability.  相似文献   
38.
目的 探讨有适应症的阵发性房颤患者行永久房间隔起搏的可行性及有效性。方法 先行心内电生理标测 ,寻找使双心房同步激动的房间隔最佳起搏点 ,采用主动固定起搏导线固定于该部位。结果  4例患者窦性心律时房间传导为 10 6 0± 4 3ms ,标测后房间隔起搏房间传导时间为 11 0± 1 1ms,(P <0 0 0 1)。达到了双心房同步起搏。 3例患者成功地植入房间隔主动固定导线 ,一例患者失败。结论 永久房间隔起搏方法在伴有房间传导阻滞的阵发性房颤患者中的应用是安全可行的。  相似文献   
39.
目的 探讨射频导管消融(radiofrequency catheter ablation,RFCA)治疗儿童快速型心律失常的有效性及安全性.方法 用体表心电图的大体定位及常规心内电生理检查,寻找消融靶点,采用温度控制方式进行RFCA.结果 心内电生理检查显示房室折返性心动过速(atrioventricular reentrant tachycardia,AVRT)10例,房室结折返性心动过速(atrioventricular nodal reentrant tachycardia,AVNRT)10例,房性心动过速(atrial tachycardia,AT)3例,特发性室性心动过速(idiopathic ventricular tachycardia,IVT)2例(1例起源于左后分支、1例起源于右心室流出道).手术即刻成功25例.术中1例在放置ABL导管时机械性的压迫希氏束出现一过性的Ⅱ~Ⅲ度房室传导阻滞(auriculo-ventricular block,AVB),给予异丙肾上腺素、阿托品、糖皮质激素处理,2 h后恢复正常的房室传导;2例放置希氏束电极时,出现Ⅰ度AVB,未经处理自行恢复正常的房室传导;22例平均随访(2.8±1.3)年未复发,3例半年后复发,其中AVNRT 2例,AVRT 1例,再次消融均获得成功.结论 RFCA治疗儿童快速型心律失常技术成熟、安全、疗效好.术后复发可能与消融点准确性、消融能量及消融时间趋于保守有关.  相似文献   
40.
In an ontogenetic study, combining morphological analysis and patch clamp recordings, a transiently appearing horizontal cell type was identified in the dentate gyrus. The cells were exclusively located in the outer third of the stratum moleculare. They were present at postnatal day 2 (P2) and could be identified with fluorescent dyes until around P14. The morphology was bipolar, with a putative axonal and a dendritic process stretching out parallel to the pial surface without any preferential direction. Patch clamp studies in the current and voltage clamp mode were performed in hippocampal slices on visually identified horizontal cells, between P4 and P7, which were subsequently stained with lucifer yellow. The cells had a low resting membrane potential, around — 55 mV. They were excitable, displaying broad action potentials (duration 3–20 ms) and, unlike mature dentate granule cells, they also expressed a strong delayed inward rectifier with properties reminiscent of the IQ current. Unlike granule cells, no postsynaptic signals could be observed during elevation of [K+]o or electrical stimulation, suggesting that the horizontal cells did not participate in functional hippocampal circuitry. We suggest that these cells represent migrating cells with subsequent differentiation to granule cells or inhibitory interneurons. Alternatively they may be part of the early radial glia or serve as transient target cells for afferent fibres between the entorhinal cortex and the dentate gyrus.  相似文献   
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