Objective To investigate the iNOS expression in cerebral aneurysm tissue, and the effect of selective iNOS inhibitor aminoguanidine on experimental cerebral aneurysm formation and serum NO production. Methods Fifty SD rats were divided into 3 groups randomly. To reproduce the aneurysm model, 40 adult male rats (weight, 250-300g) were subjected to ligation of the left common carotid artery and the posterior branches of both renal arteries. One week after the operation, 1% saline was given for drinking to substitute plain water. Each rat received an intraperitoneal injection of aminoguanidine (100mg/kg)(group A, n=20) or normal saline (group B, n=20) beginning in the morning of postoperative day(POD) 1 through POD 150. Group C rats received no operation to serve as the control group (n=10). Arterial wall at the bifurcation of the right anterior cerebral artery and olfactory artery as well, as serum were harvested after 5 months. Blood pressure was measured before the experiment and 5 months after the experiment procedure. NO levels were indirectly quantified by measuring nitrate levels. The incidence of formation of aneurysm, pathological findings and expression of iNOS in aneurysmal wall were evaluated with HE staining and immunohistochemical analysis. Results Selective iNOS inhibitor aminoguanidine could significantly inhibit the formation of aneurysms and lower serum levels of nitrate. The pathological features of the experimental aneurysms were similar to that in human, including discontinuation or disappearance of tunica intima, thinning or disappearance of the elastic and muscular layers, and substitution of artery wall by a layer of fibrous connective tissue. iNOS immunoreactivity could be seen in the smooth muscle cells of the intimal pad and distal portion of the newly formed aneurysm. Conclusion Cerebral aneurysm can be induced in rats by alteration in hemodynamics, and it is related to formation of local expression of iNOS and high NO level.

Objective To study the advantages and procedure of telovelar approach for resection of the lesion in the fourth ventricle. Methods Telovelar approach to the fourth ventricle was executed in 17 cases. Among these patients, seven were females and 10 were males. The age ranged from 5 years to 49 years with mean age of 26.6 years. Pathologically, there were 5 medulloblastomas, 5 ependymomas, 2 epidermoids, 2 brain cysticercosis, and 3 choroid plexus papillomas. During the operation, the medullotonsillar space of the cerebellomedullary fissure and the urulotonsillar space were sharply dissected to release the tonsils from uvula and medullar oblongata bilaterally. According to the size of the neoplasm, the tela or both tela and velum were incised. The fourth ventricle was exposed adequately and the lesion was removed. All operations were performed with the help of microscope. The dura was sutured securely. Results The space occupying lesions were removed totally in all cases and all patients recovered very well, and threre was no mortality or serious disability. With 3 to 21-month follow-up in 11 cases, no death or serious disability was found, and the CT or MRI in 8 patients showed no recurrence. Conclusion The telovelar approach can provide adequate exposure to remove the lesion in the fourth venticle. The inferior vermis need not be incised, so a minimum amount of brain tissue was injured, and postoperative complication is decreased.

Objective To study the role of VEGF on the growth of hypertensional saccular aneurysm and its mechanism. Methods Twenty-four SD rats were divided into 2 groups randomly (A and B, each with 12 rats). Saccular aneurysms of the carotid artery were reproduced by treatment of initial segment of the external carotid artery (1mm long) with elastase. In group A, the posterior branches of both renal arteries were ligated in order to produce marked elevation of blood pressure. In Group B hypertension was not produced to serve as the control group. After 8 weeks, the blood pressure and the size of the aneurysms were measured. Then formalin was infused into the arteries for fixation, and aneurysms were resected. The expression of vascular endothelial growth factors (VEGF) in aneurysmal wall was assessed with immunohistochemical analysis. Results The size of aneurysms: after 8W, significant difference was found between A and B group (P

s Objective To observe the changes in the expression of ?-amyloid precursor protein (?-APP) in selected brain areas in early stage of diffuse axonal injury (DAI) in rats. Methods DAI was induced in SD rats by a self-made rotating injury device. 16 rats in injury group were sacrificed by decapitation at 3 hours and 6 hours post-trauma, while the other 8 rats in sham injury group were put to death after 24 hours. The samples of the rat brain were stained with ?-APP for immunohistochemistry in order to detect the early stage pathological changes in subcortex white matter, hippocampus, corpus callosum and brain stem at different time points. Results The ?-APP expression was positive at 3 hours and was particularly strong at 6 hours after injury. The results of semi-quantitative analysis showed a significant differentiation of 3 hours and 6 hours in the immuno-positive expression of brain stem, corpus callosum and hippocampus. Histological results demonstrated that DAI occurred in all rats of injury group. Conclusion ?-APP is a kind of sensitive and useful immunochemical marker for early DAI diagnosis, and it indicates axonal lesion or breakage.

Objective To explore the formation of intravascular microthrombosis in the brain after traumatic brain injury in rat in order to study the potentially causal linkage between thrombosis and post-traumatic cerebral ischemia. Methods Lateral fluid percussion injury (FPI) model was reproduced in the present study to prodace acute brain injury in rats. The rats were sacrificed at 12, 24, 72 hours and 7days after traumatic brain injury. Sham-injured animals received identical craniotomy without FPI. Pathological studies were performed to study the distribution and severity of intravascular microthrombosis in the brain. The difference in the severity of intracerebral thrombosis between groups was evaluated. Results Abundant fibin thrombi were found in all injured rats as compared with the controls (P

Objective To establish a simple and reliable method for primary culture and purification of embryonic dorsal root ganglion neurons. Methods Dorsal root ganglions (DRG) from rat embryos were isolated under microscope and dissociated in trypsin. The dissociated neurons were treated with 5-fluorouracil for purification. Immunocytochemistry was performed by double staining with anti-calcitonin gene-related peptide and anti-NF200 antibodies to evaluate the purification rate of DRG neurons. Results Isolated and cultured DRG neurons survived and grew nicely in the basis medium for neurons, and the purified rate of DRG neurons could reach to around 93%. Conclusion The above method is very useful to obtain dorsal root ganglion neurons and to purify the neuronal population.

Objective To explore the potential mechanism of efficacy of imipramine treatment in the regeneration of hippocampus neuron after traumatic brain injury in rat.Methods Lateral hydraulic battering injury(HBI)was used to induce acute brain injury in rats.Forty male SD rats were randomly assigned to four groups:HBI with imipramine treatment group,HBI without treatment group,sham injury with imipramine treatment group and sham injury without treatment group.Animals of all the four groups were sacrificed for histological evaluation two months after treatment.Proliferating cells and neurons in hippocampus were counted and compared between groups.Results Proliferating cells and neurons were found to be obviously increased in all injured rats compared with sham injured animals(P

The aim was to look for the method for getting highly purified population and large amount of Schwann cells from the newborn rats. Sciatic nerves from 1～3 days old SD rats were taken out . The Schwann cells were cultured and purified by modified repeated explanation, and fibroblastic cells were removed by rapid trysinization , differential adhesion and anti mitosis methods. The Schwann cells were identified by indirect immunocytochemistry with mouse anti S 100 protein McAb. The result showed that the purity of Schwann cells was more than 95%, and the cells were in a good state. It is considered that the methods are simple and convenient , and a great number of highly purified Schwann cells can be acquired by them.

To assess the indication, intraoperative monitoring with selective shunting and surgical outcomes of carotid endarterectomy for patients with contralateral carotid occlusion, the clinical manifestations, imaging data, surgical methods and results of 16 patients were analysed retrospectively. It was verified that the surgical risk of these patients was not as high as prediction,satisfactory results coold be achieved with intraoperative monitoring, selective shunting and skilled surgical techniques. It is reasonable to offer the following typical treatment examples: Carotid endarterectomy should be performed for patients with symptomatic carotid stenosis irrespective of the contralateral carotid occlusion, while medical therapy should be maintained for patients with asymptomatic carotid stenosis and contralateral carotid occlusion. maintained. If the asymptomatic stenosis is found to be progressing in noninvasive testing, then a prophylactic endarterectomy should be considered.

Exposure of the distal internal carotid artery is very important and difficult in carotid endarterectomy for patients with high bifurcations or extension of the atherosclerotic plaque into the distal internal carotid artery. Exposure techniques are introduced based on the surgical experiences of 28 cases.