Objective
To observe the functional state of the optic nerve and discover the injury of visual pathway function in time under general ane sthesia. The flash visual evoked potential (F-VEP) was used to monitor visual function during orbital surgery.
Methods
A total of 252 out of 282 patients undergoing orbital surgery under general anesthesia were successfully monitored by F-VEP during the surgery. All patients were monitored by this method under the following conditions:consious state before operation, under general anaesthesia, during and after dissection of orbital tumor and at the end of operation.
Results
①There was no significant difference of wave amplitude and latency under general anesthesia and consciousness condition. ②The amplitude and latency of F-VEP were normal in the orbital surgery withou toptic nerve injury. ③Pulling and oppression of optic nerve could cause temporary wave loss, but the wave recovered after removal of the pull and oppression. ④ The wave loss of F-VEP would occur immedicately when optic nerve was severe injured and its blood supply was deficient. Since the application of the visual function monitoring, 24 cases were treated in time during disturbance of visual function and no patient has unexpected visual loss during orbital surgery.
Conclusion
The intraoperative monitoring of F-VEP during orbital surgery can decrease the proportion of permanent visual loss caused by orbit al surgery, and help the surgical procedures go to function-anatomy stage from experience-anatomy stage.
(Chin J Ocul Fundus Dis, 2001,17:260-263)
The capacity of embryonic spinal cord tissue in the repair of injured structure of spinal cord has been noted for years. In order to investigate the embryonic spinal cord graft in the repair of motor function of injured spinal cord, the embryonic spinal cord tissue was transplanted to the hemisection cavity in spinal cord in adult rat. One hundred adult Wistar Rats were used to simulate the hemisectional injury of spinal cord by drilling 2-3 mm cavity in lumbar enlargement. Sixty rats were treated with rat embryonic spinal cord tissue grafting while the other forty were chosen as control. The outcome was evaluated according the combined behavioural score (CBS) and motor evoked potential (MEP) in the 1, 2, 4 and 12 weeks. The grafting group was superior to the control as assessed by CBS (P lt; 0.05), especially within 4 weeks. (P lt; 0.01). The restoration of the latent peak of early wave(P1, N1) was better in the grafting group, too. This suggested that embryonic spinal cord graft could improve the recovery of motor function of injured spinal cord in adult rat. The effect of the embryonic spinal cord tissue graft might be concerned with its secretion of several kinds of neurotrophic factors, nerve growth factor, nerve transmitted factor, or adjustment of hormone.
Pathological neural activity in subthalamic nucleus (STN) is closely related to the symptoms of Parkinson's disease. Local field potentials (LFPs) recordings from subthalamic nucleus show that power spectral peaks exist at tremor, double tremor and tripble tremor frequencies, respectively. The interaction between these components in the multi-frequency tremor may be related to the generation of tremor. To study the linear and nonlinear relationship between those components, we analyzed STN LFPs from 9 Parkinson's disease patients using time frequency, cross correlation, Granger casuality and bi-spectral analysis. Results of the time-frequency analysis and cross-frequency correlation analysis demonstrated that the power density of those components significantly decreased as the alleviation of tremor and cross-correlation (0.18~0.50) exists during tremor period. Granger causality of the time-variant amplitude showed stronger contribution from tremor to double tremor components, and contributions from both tremor and double tremor components to triple tremor component. Quadratic phase couplings among these three components were detected by the bispectral approaches. The linear and nonlinear relationships existed among the multi-components and certainly confirmed that the dependence cross those frequencies and neurological mechanism of tremor involved complicate neural processes.
Objective To investigate the cell growth inhibition and apoptosis induced by rapamycin on human hepatocellular carcinoma Bel-7402 cells and to study the role of mitochondrium membrane potential in the process of apoptosis. Methods Bel-7402 cells in vitro were given 5, 10, 20, 30, 40 and 50 nmol/L different concentrations of rapamycin, and the cell growth inhibiting ratio of Bel-7402 was assessed by MTT assay. The changes of morphology of Bel-7402 were observed by Hoechst 33258 staining and flow cytometry (FCM), respectively; The cell mitochondrial membrane potential was detected by using JC-1 staining method. Results Rapamycin could inhibit the growth of Bel-7402 cells significantly by inducing apoptosis, and the growth suppression and the cell apoptosis both presented time-effect relationship and were also dose-dependent. The rates of inhibiting and cell apoptosis after 72 h exposure to 50 nmol/L rapamycin were significantly higher that those of other groups (P＜0.01). Typical morphological changes of cell apoptosis were observed very clearly after the Bel-7402 cells had been exposed to rapamycin for 48 hours using Hoechst 33258 staining method, and it was also observed that the mitochondrial membrane potential decreased when apoptosis occured (P＜0.01). Conclusion Rapamycin could inhibit the growth of Bel-7402 cells by inducing cell apoptosis, and the descent of mitochondrial membrane potential may play an important role in the process of cell apoptosis.
OBJECTIVE: To prevent the senescence of ’seed cells’ for tissue engineering, the life span of human fibroblasts is extended by reconstitution of telomerase activity, and the osteogenic potential of these fibroblasts are tested. METHODS: The pGRN145 plasmids encoding human telomerase reverse transcriptase (hTERT) were introduced into the normal human primary fibroblasts by electroporation. Telomerase activity was analyzed by TRAP-PCR assay. The beta-galactosidase stain was used to indicate the signs of cell senescence. The hTERT positive fibroblasts were then induced to form bone nodules. The bone nodules were stained by tetracycline and Alizarin Red S. RESULTS: Stable telomerase activity could be detected in the transfected fibroblasts and no signs of cell senescence were found in the fibroblasts cultured for more than 50 doublings. The hTERT positive fibroblasts could form bone nodules when they were cultured in vitro induced by bone morphogentic protein 2 and tumor necrosis factor-alpha. CONCLUSION: The fibroblasts with reconstituted telomerase activity reserve their osteogenic potential.
Objective To investigate the characteristics of multifocal visual evoked potential (mf-VEP) in healthy individuals, and provide normal reference values for its clinical application. Methods The mf-VEP of 37 healthy individuals (70 eyes) were examined by VERIS ScienceTM4.0. The visual stimulus was adart board with patterns consisted of 60 patches spanning a 25°visual field. The length of m-sequence was 214-1. The results were recorded by bipolar occipital straddle. The signal was amplified 100 K and was put through a band-pass filter between 3 and 100 Hz. The first slice of the second order kernel was analyzed by VERIS software. The summed responses of fields with different stimulus were a nalyzed and compared according to different ages, genders and eyes.Results The latencies and response densities of amplitude had statistically significant differences both in dimidiate and quartered field（Plt;0.05）. The latencies in ≥50 year group were much more delayed in some sectors of the visual field than those in lt; 50 year group（Plt;0.05）. The latencies of women were shorter than those of men（Plt;0.05）. There was no obvious difference of latencies and response densities of amplitude in each field sectors between both eyes（Pgt;0.05）. Conclusions The mf-VEP of healthy individuals can reflect the VEP at different field ocations objectively with its specific physiological characteristics, which may provide normal reference values for its clinical application.(Chin J Ocul Fundus Dis，2003，19：269-332)
Spinal cord stimulation (SCS) for pain is usually implanted as an open loop system using unchanged parameters. To avoid the under and over stimulation caused by lead migration, evoked compound action potentials (ECAP) is used as feedback signal to change the stimulating parameters. This study established a simulation model of ECAP recording to investigate the relationship between ECAP component and dorsal column (DC) fiber recruitment. Finite element model of SCS and multi-compartment model of sensory fiber were coupled to calculate the single fiber action potential (SFAP) caused by single fiber in different spinal cord regions. The synthetized ECAP, superimposition of SFAP, could be considered as an index of DC fiber excitation degree, because the position of crests and amplitude of ECAP corresponds to different fiber diameters. When 10% or less DC fibers were excited, the crests corresponded to fibers with large diameters. When 20% or more DC fibers were excited, ECAP showed a slow conduction crest, which corresponded to fibers with small diameters. The amplitude of this slow conduction crest increased as the stimulating intensity increased while the amplitude of the fast conduction crest almost remained unchanged. Therefore, the simulated ECAP signal in this paper could be used to evaluate the degree of excitation of DC fibers. This SCS-ECAP model may provide theoretical basis for future clinical application of close loop SCS base on ECAP.
Neuron is the basic unit of the biological neural system. The Hodgkin-Huxley (HH) model is one of the most realistic neuron models on the electrophysiological characteristic description of neuron. Hardware implementation of neuron could provide new research ideas to clinical treatment of spinal cord injury, bionics and artificial intelligence. Based on the HH model neuron and the DSP Builder technology, in the present study, a single HH model neuron hardware implementation was completed in Field Programmable Gate Array (FPGA). The neuron implemented in FPGA was stimulated by different types of current, the action potential response characteristics were analyzed, and the correlation coefficient between numerical simulation result and hardware implementation result were calculated. The results showed that neuronal action potential response of FPGA was highly consistent with numerical simulation result. This work lays the foundation for hardware implementation of neural network.
Motor imaging therapy is of great significance to the rehabilitation of patients with stroke or motor dysfunction, but there are few studies on lower limb motor imagination. When electrical stimulation is applied to the posterior tibial nerve of the ankle, the steady-state somatosensory evoked potentials (SSSEP) can be induced at the electrical stimulation frequency. In order to better realize the classification of lower extremity motor imagination, improve the classification effect, and enrich the instruction set of lower extremity motor imagination, this paper designs two experimental paradigms: Motor imaging (MI) paradigm and Hybrid paradigm. The Hybrid paradigm contains electrical stimulation assistance. Ten healthy college students were recruited to complete the unilateral movement imagination task of left and right foot in two paradigms. Through time-frequency analysis and classification accuracy analysis, it is found that compared with MI paradigm, Hybrid paradigm could get obvious SSSEP and ERD features. The average classification accuracy of subjects in the Hybrid paradigm was 78.61%, which was obviously higher than the MI paradigm. It proves that electrical stimulation has a positive role in promoting the classification training of lower limb motor imagination.
ObjectiveTo investigate the effects of hippocampal long-term potentiation (LTP) on cognitive dysfunction in immature epileptic rats.
MethodsImmature epileptic rats were established by intraperitoneal injection of lithium chloride-pilocarpine (li-pilo). Racine classification standard modified by Becker was used to evaluate behavior of epileptic seizure, and the survival rats within RacineⅣmagnitude were selected in the experiment. The function of learning and memory of epileptic rats when they were adult was assessed using Morris water maze experiment, and their independent exploratory behavior was evaluated by the open-field test. Field potential was recorded by electrophysiological technology to detecte whether hippocampal LTP was essential of cognitive dysfunction.
ResultsThe function of learning and memory was significantly impaired when compared with controls(n=8, t=10.86, P < 0.05;n=8, t=9.98, P < 0.05). In addition, independent exploratory behavior was significantly reduced when compared with controls(n=8, t=12.89, P < 0.05). Besides, CA1 hippocampal LTP induced by high-frequency stimulation presented the significant inhibition in epileptic rats with cognitive dysfunction when compared with controls(Slope:n=8, t=13.32, P < 0.05;Amplitude:n=8, t=20.02, P < 0.05).
ConclusionInhibition of CA1 hippocampal LTP may be implicated in cognitive dysfunction of epileptic rats.
