BACKGROUND: Recent studies show that the neurons in central nervous system have the regenerating ability under certain suitable environment such as elevating the c-AMP level of the neuron. But the mechanism is unclear.OBJECTIVE: To investigate the effect of protein kinase A inhibitor H-89and PI3-kinase inhibitor, wortmannin, on Cholera Toxin (CTx) in promoting the axon regeneration of retinal ganglion cells (RGCs) after distal axotomy of the optic nerve in adult hamsters.DESIGN: A randomized and controlled animal experiment SETTING: Department of Histology and Embryology of Guangzhou Medical College and Sun Yat-sen University of Medical Sciences MATERIALS: This experiment was conducted in the Guangzhou Medical College and Sun Yat-sen University of Medical Sciences between January 2000 and December 2001. Totally 25healthy adult male hamsters were chosen and randomly divided into 5 groups: model group; experimental control group; CTx group; CTx +protein kinase A inhibitor group; CTx +PI3-K inhibitor group, with 5 animals in each group.METHODS: A 2 cm segment of autologus sciatic nerve was removed and desheathed. The proximal end of the sciatic nerve was connected to the proximal stump of the optic nerve (ON). .The wound was enveloped with gelatin sponge. The remaining portion of sciatic nerve was placed on the top of the skull. Model group: a segment of autologus sciatic nerve was connected to the ON proximal stump. Experimental control group: Received an injection of Na2EDTA/NaCL solution introvitreally based on the treatment in control group. CTx group: CTx (1000 pg/eye)was injected introvitreally on the basis of the treatment in the control group. CTx+ protein kinase A inhibitor group: 3μL protein kinase A inhibitor H89 (60μmol/L)was injected introvitreally 30 minutes before operation, the other treatment was like mannin (1μmol/L) was injected introvitreally 30 minutes before operation,and the other treatment was like that of CTx group.⑤CTx+PI3-K inhibitor group: 3 μL PI3-K inhibitor wortmannin (1μmol/L) was injected introvitreally 30 minutes before operation,and the other treatment was like that of CTx group. Animals in each group survived for 4 weeks. Administration was given every other 5 days. H-89,wortmannin were given once five days and CTx was also given 30 minutes later every time. There were four times in total. 3 days before operation, a piece of gel foam soaked with 30g/L GB was applied to the proximal end of transected PN to label the RGCs conversely. Observation was performed under the fluorescence microscope and the number of GB-labeled cells was counted.MAIN OUTCOME MEASURES: The quantity of retrograde labeled axon regenerating RGCs in each groupRESULTS: There were fewer regenerating RGCs in the model group and experimental control group (2.6±0.87,2.4±0.95),and the number of them was significantly higher in the CTx group than in the control group and experimental group [(43.2±1.36),q=73.294 and 73.655,P ＜ 0.001]. There was no significant difference of the mean number of axon regenerating RGCs between CTx + protein kinase A inhibitor H-89 group and model group and experimental control group [(3.2±0.16), q=1.083 and 1.444, P＞ 0.05]; The mean number of axon regenerating RGCs in the three groups was significantly lower than that in the CTX group, with significant difference (q=72.211, P ＜ 0.001). The mean number of axon regenerating RGCs was higher in the CTx+PI3-K inhibitor group (9.6±1.85)than in the model group and experimental control group (q=12.637 and 12.998, P ＜ 0.05);but significantly lower than in the CTx group (q=60.657, P ＜ 0.001).CONCLUSION: CTx can promote the axon regeneration of RGCs after distal axotomy of the optic nerve; its promoting function can be blocked by H-89 and Wortmannin

Objective To investigate the effects of Colera Toxin(CTx) on the regeneration of retinal ganglion cells (RGCs) after distal axotomy in adult hamsters. Method After transecting the optic nerve(ON) intracranically,an autologus sciatic nerve (attached graft,AG) was removed and connected to the proximal stump of the ON.CTx was injected and/or a 2mm segment of sciatic nerve(SN) was inserted intravitreally.Animals were divideded into six groups:control group 1(AG group) and control group 2(solution group);AG+SN group;AG+CTx group;AG+SN+CTx group;effect and dosage group.Animals in the former five groups were allowed to survive for 4-6 weeks respectively.Granular blue fluorescent retrograde labeling method was used to measure the quantity of regenerating RGCs of control and experiment animals. Results The mean number of regenerating RGCs in AG+CTx groups were increased and significantly higher than those in control group 1 and control group 2 at each time point(P

Objective To investigate the effects of Cholera Toxin(CTx)on the cAMP level and the survival as well as the apoptosis of retinal ganglion cells (RGCs) after distal axotomy of the optic nerve.Method After transecting the optic nerve intracranially, CTx was injected intravitreally. Fluorescent retrograde tracing method and TUNEL(TdT-mediated dUTP nick end labeling)technique were used to show the surviving RGCs and the apoptotic cells in the ganglion cell layer. The Brown's radioimmunoassay method was used to measure the cAMP level of the retina. Result The cAMP level of the normal retina was 6.22?2.02pmol/g/retina. The mean density of RGCs in the normal retina was 2 192?66/mm 2 and it decreased to 1 520?116/mm 2、736?39/mm 2 and 466?53/mm 2 at 1W、2W and 3W respectively after distal axotomy. The densities of RGCs in the distal axotomy groups treated with CTx and killed at 1W、2W and 3W were 1 642?122/mm 2、1 091?107/mm 2、 748?35/mm 2 respectively and were significantly higher than those of distal axotomy group without CTx treatment. Conclusions The results show that CTx can elevate cAMP level of the retina and promote the survival of RGCs and inhibit the apoptosis of RGCs after distal axotomy of the optic nerve in adult hamsters.

BACKGROUND:There are reports concerning effects of E-Selectin,a cellular adhesion molecule,on selectively adhesion among cells,regulation of leukocyte homing and exudation,and tumor cell transfer.However,there are no reports addressing E-Selectin qualitation and positioning study,as well as relationship with embryonic liver hematopoietic function during embryonic liver development.OBJECTIVE:To study the relationship between the E-selectin expression and the morphodifferentiation of the hepatic cells,the sinusoids endothelium as well as hematopoiesis during the embryonic development of mouse liver.METHODS:The mouse fetuses or fetal liver tissues from embryo day 11.5(E11.5)to postnatal day 15.5(P15.5)were dissected,fixed and embedded in paraffin.The sections were stained with hematoxylin and eosin and subjected to immunohistochemistry.The development of liver structure and the morphology of cells were observed under an optical microscope.The immunohistochemistry was taken to investigate the expression and localization of E-selectin in fetal livers at different developmental stages.RESULTS AND CONCLUSION:The progenitor liver cells gathered to form the hepatic parenchymal cords at E11.5.The hepatic parenchymal cords were separated by sinusoids with sporadic haemopoietic stem cells in it.The progenitor liver cells began to proliferate and differentiate at E12.5.From then on,the parenchymal cells increased,the volume of the hepatocytes became largei and the karyoplasmic ratio was decreased.The hepatic lobules were formed at natal time.The lacuna of the hepatic sinusoid became narrower and the endothelial cells grown to contiguous.At E12.5,the hematopoietic cells began its hematogenesis and reached its peak at E13.5 E15.5,and then both the blood-forming tissue and hematogenesis decreased gradually.E-Selectin expressed in the membrane of the endothelial cells from E11.5 to E15.5,located in endothelial cell membrane,and disappeared gradually along with the development of endothelial cells and the maturation of the hepatic cells.Above-mentioned results indicated that the most important time for the development of the individual cells in fetus liver is E12.5-E15.5.The expression of E-Selectin was appeared in the sinusoid endothelium,which is associated with the haematogenesis of fetus liver and the differentiation of hepatic cells.

Medical curriculum integration mode is the development trend of medical education re-form. The Institute of Basic Science of Guangzhou Medical University has given full consideration to the present situation at home and abroad and its own conditions, modularized the traditional basic medicine ex-periment course according to the similar content, and formed medical human morphology (human anatomy and tissue embryology, pathology), immune and pathogenic biology (microorganisms, parasites, immunology), biological science (cell biology, genetics, biological sciences) three modules, and then gradually established and perfected a scientific and effective comprehensive morphology experiment teaching material, teaching method, examination and evaluation system based on the teaching content of integration. The establishment of this new basic medical morphology course system, which is based on the organs and systems, shows the less content redundancy, good structural and overall coordination of the new curriculum, so as to play its comprehensive advantages and conform to the trend of the development of the medical education.

BACKGROUND:It is reported that the cellsurface antigen may be damaged by the trypsin enzyme in some extent and the cellactivity may also be influenced, as a result of which, the subsequent separation and fol ow-up-test wil be affected. Accutase enzymes possess the activities of protease and col agen enzyme and need no special termination or cleaning at the end of digestion. Another special function of accutase enzyme is to protect cellsurface antigen and thus it has been widely applied in the stem celldigestion and culture.
OBJECTIVE:To compare the digestive effect of accutase enzymes and trypsin enzyme in the separation and original culture of spermatogonial stem cells.
METHODS:The testes of 5-7 days male Kunming mice (n=45) were col ected and primarily digested with col agenas. The suspension of digested tissue was divided into three parts with the same volume named accutases enzyme group, trypsin enzyme group and mixed enzyme group (trypsin enzyme and hyaluronidase). For the comparison of testis digestive status and the time required for the formation of single cells, the micrographs were taken at 1, 3 and 5 minutes respectively after enzyme digestion. The total number and the mortality of the single cells were estimated and compared. The leydig cells and sertoli cells were removed by differential adherent method and the remained spermatogenic cells were then treated with CD90.2 immune magnetic beads. The selected spermatogonial stem cells were subsequently labeled by glial cellline-derived neurotrophic factor receptor alpha-1 and sorted with flow cytometry. The number of spermatogonial stem cells positive for glial cellline-derived neurotrophic factor receptor alpha-1 in CD90.2+and CD90.2-cells was compared within different groups.
RESULTS AND CONCLUSION:The digestive capacities of different enzyme were different. Accutases enzyme obtained the single cellsuspension more quickly than trypsin enzyme and mixed enzyme, and had the least cellmasses and broken cellmembrane than the other two groups. After the differential attached treatment, the highest total number of CD90+spermatogonial stem cells and lowest cellmortality could be found in the accutases group, when compared with the other groups. The results of cellsorting by flow cytometry showed a higher rate (72.24%) of GFRα1+/CD90+cells in the accutases group than the trypsin group (51.16%) and mixed enzyme group (71.27%). The GFRα1+/CD90-number in the accutases group was lower (15.03%) than that of the trypsin group (18.8%) and mixed enzyme group (24.23%), respectively. The results indicate a better effect of accutases enzyme on the primary separation of spermatogonial stem cells than that of trypsin or mixed enzyme.

The effects on frozen-thawed sperm survival rate of 16 different cryoprotective media containing different ratio of glycerol (0%, 2.5%, 5% and 7%) and sucrose (0,25,50 and 100 mmol/L) were compared. The results showed that glycerol-sucrose cryoprotective media had better effect on cryoprotection of spermatozoa than that of traditional glycerol protective medium, and appropriately increasing the concentration of sucrose and decreasing the concentration of glycerol could improve sperm motility, and especially benefit to preserve sperm linear motility at 12h postthawed. Using 5% glycerol combined with 50 mmol/L sucrose as cryoprotective medium, the sperm survival rate at 0, 6, 12h postthawed was 85.38%, 51.22%, 33.38%, respectively, the linear moving sperm survival rate was 83.74%, 33.33%, 18.38% respectively.

Objective To explore the effect of anterior decompression plus posterior intradural release in treatment of old thoracolumbar fractures with paraparesis. Methods A total of 22 patients with old thoracolumbar fractures with paraparesis were admitted to our hospital since January 2004 to Jan-uary 2008. Before admission, all patients were treated with decompression and internal fixation with pos-terior pedicle system, with bony compression to the spinal cord found through CT scanning and intact spi-nal cord found by MRI but without obvious neurofunction recovery. Of all, 20 patients were kept with the original posterior fixation except for two patients that were fixed with Z-plate after removal of posterior hardware. Autologous bone grafts from iliac were utilized in all patients. Intradural release was done 3-6 months after anterior decompression. Results Of all, 19 patients were followed up for 17-49 months (average 28 months). Twenty patients obtained varied recovery of neurofunction after anterior decompres-sion, with ASIA motor scores increasing from average 59.4 points before decompression to 71.3 after de-compression. The followed-up patients won further recovery after secondary posterior intradural release, with ASIA motor scores further increasing to average 80.6 points. Conclusion For patients with old thoracolumbar fractures combined with paraparesis, the release of intradural sear and fibrocompression is also important besides anterior decompression.

This research is to construct a basic medical sciences’experimental teaching system in order to cultivate innovative talents. It is guided by cultivating innovative practical ability and post compe-tence and implements a teaching mode with “five combinations”by integrating teaching resources, strength-ening interdisciplinary combination , integrating curriculum and organ systems , and optimizing teaching modules and experiment content. A preliminary personnel training mode and experimental teaching system have been constructed for innovative talent cultivation, and correspondently a diversified experiment exami-nation system and teaching quality monitoring system have been constructed through teaching practice, which aims at continuously improving experiment teaching quality and talent training quality.

Multiple factors such as traditional history evolution, resource allocation and management mechanism all restrict the discipline development of basic medical sciences and the enhancement of postgraduate education quality. Guangzhou Medical University starts from top-level design, focuses on joint efforts of discipline construction and adopts a series of reform measures to promote first-class basic medical sciences discipline construction and enhance the postgraduate education quality, such as transforming the architecture of scientific institutions, grasping the discipline direction, setting double-tutor system, optimizing the tutor team, promoting curriculum reform, strengthening communication between domestic and overseas and selecting excellent students. Practice shows that positioning properly and developing with unique features based on joint efforts of discipline are effective approaches to build high-level teaching-research medical universities.