含有血运雪旺氏细胞的鞘膜管桥接神经缺损的实验研究

长段、粗大周围神经缺损的修复,由于自体神经移植供区来源困难,迫切需要一种理想的非神经移植材料。最理想的模型应是带血管自体神经移植,其中基底膜管具有促轴突生长并有生长导向作用,成活的雪旺氏细胞分泌促神经再生物质。近年来报道,将无血运雪旺氏细胞植入非神经桥接体中取得一定效果。自1987年3月始我们采用含有血运雪旺氏细胞的鞘膜管桥接兔坐骨神经缺损实验研究,结果同自体神经移植。

牙周组织工程实验性牙周缺损模型的研究进展

牙周组织工程研究的前提是建立可重复评价牙周再生的实验性牙周缺损模型。本文主要对外科手术造成的急性缺损进行综述,分别就近年与牙周组织工程研究有关的水平骨上袋模型、骨内袋模型、根分叉病变模型、牙周开窗模型予以阐述,为探讨各种干预因素对牙周再生的影响奠定临床前期实验基础。

实验性室间隔缺损心肌血管紧张素Ⅱ受体表达的变化

目的 探讨实验性室间隔缺损 ( VSD)动物左右心室心肌血管紧张素 受体的改变。方法 建立猪实验性室间隔缺损动物模型 ,术后 1月取左右心室组织 ,通过放射性配体受体结合分析法测定每 10 6个细胞上血管紧张素 受体 ( AT1 R、AT2 R)的最大结合量 ( Bmax)和平衡解离常数 ( KD)。结果 假手术组与正常组动物受体的 Bmax和KD改变无统计学意义 ,手术组动物左室 AT1 R、右室 AT1 R和 AT2 R的 Bmax值 (分别为 188.42± 13 3 .97、2 72 .14±2 3 2 .74、40 .42± 3 4.76fmol/ 10 6 ,对照组 AT1 R和 AT2 R的 Bmax值左室为 2 9.2 0± 19.5 0和 2 .90± 0 .64 ,右室为76.72± 5 1.2 1和 9.63± 1.2 7fm ol/ L )增高明显 ( P<0 .0 5 )。结论 心内左向右所引起的心室容量负荷过重 ,导致AT1 R的表达增高 ,是 VSD心室肥厚及重构的重要机制 ;AT2 R在右心室表达增高 。

解尔分思对家兔实验性颅骨缺损修复影响的研究

本文研究了解尔分思对家兔实验性颅骨缺损修复的影响。结果表明：解尔分思对家兔实验性颅骨缺损的修复确有促进作用。

求解物理问题的一种有效途径——补偿法

补偿法能有效地解决一些较复杂的物理问题。文章从系统几何结构的补偿、系统演进路径的补偿、系统物理过程的补偿和实验测值缺损的补偿等几个方面对补偿法进行了讨论。

Alanyl-glutamine dipeptide inhibits hepatic ischemiareperfusion injury in rats

AIM： To investigate the protective effect and mechanism of alanyl-glutamine dipeptide （Ala-GIn） against hepatic ischemia-reperfusion injury in rats. METHODS： Rats were divided into group C as normal control Group （/7=16） and group G as alanyl-glutamine pretreatment 07=16）. Rats were intravenously infused with 0.9% saline solution in group C and Ala-GIn -enriched （2% glutamine） 0.9% saline solution in group G via central venous catheter for three days. Then all rats underwent hepatic warm ischemia for 30 min followed by different periods of reperfusion. Changes in biochemical parameters, the content of glutathione （GSH） and the activity of superoxide dismutase （SOD） in liver tissue, Bcl-2 and Bax protein expression and morphological changes of liver tissue were compared between both groups. RESULTS： One hour after reperfusion, the levels of liver enzymes in group G were significantly lower than those in group C （P〈0.05）. Twenty-four hours after reperfusion, the levels of liver enzymes in both groups were markedly recovered and the levels of liver enzyme in group G were also significantly lower than those in group C （P〈0.01）. One and 24 h after reperfusion, GSH content in group G was significantly higher than that in group C （P 〈0.05）. There was no statistical difference in activities of SOD between the two groups. One and 24 h after reperfusion, the positive expression rate of Bcl-2 protein was higher in group G than in group C （P〈0.05） and the positive expression rate of Bax protein was lower in group G than in group C （P〈0.05）. Histological and ultrastructural changes of liver tissue were inhibited in group C compared to group G. CONCLUSION： Our results suggest that Ala-GIn pretreatment provides the rat liver with significant tolerance to warm ischemia-reperfusion injury, which may be mediated partially by enhancing GSH content and regulating the expression of Bcl-2 and Bax proteins in the liver tissue.

Identification of differentially expressed genes after partial rat liver ischemia/reperfusion by suppression subtractive hybridization

AIM: To identify potential diagnostic target genes in early reperfusion periods following warm liver ischemia before irreversible liver damage occurs. METHODS: We used two strategies (SSH suppression subtractive hybridization and hybridization of cDNA arrays) to determine early changes in gene expression profiles in a rat model of partial WI/R, comparing postischemic and adjacent nonischemic liver lobes. Differential gene expression was verified (WI/R; 1 h/2 h) and analyzed in more detail after warm ischemia (1 h) in a reperfusion time kinetics (0, 1, 2 and 6 h) and compared to untreated livers by Northern blot hybridizations. Protein expression was examined on Western blots and by immunohistochemistry for four differentially expressed target genes (Hsp70, Hsp27, Gadd45a and IL-1rI). RESULTS: Thirty-two individual WI/R target genes showing altered RNA levels after confirmation by Northern blot analyzes were identified. Among them, six functionally uncharacteristic expressed sequences and 26 known genes (12 induced in postischemic liver lobes, 14 with higher transcriptional expression in adjacent nonischemic liver lobes). Functional categories of the verified marker genes indicate on the one hand cellular stress and tissue damage but otherwise activation of protective cellular reactions (AP-1 transcription factors, apoptosis related genes, heat shock genes). In order to assign the transcriptional status to the biological relevant protein level we demonstrated that Hsp70, Hsp27, Gadd45a and IL-1rI were clearly up-regulated comparing postischemic and untreated rat livers, suggesting their involvement in the WI/R context. CONCLUSION: This study unveils a WI/R response gene set that will help to explore molecular pathways involved in the tissue damage after WI/R. In addition, these genes especially Hsp70 and Gadd45a might represent promising new candidates indicating WI/R liver damage.

Dual protective role of HO-1 in transplanted liver grafts:A review of experimental and clinical studies

Liver transplantation is considered as the most effective treatment for end-stage liver disease.However,serious complications still exist,particularly in two aspects:ischemia and subsequent reperfusion of the liver,causing postoperative hepatic dysfunction and even failure;and acute and chronic graft rejections,affecting the allograft survival.Heme oxygenase(HO),a stressresponse protein,is believed to exert a protective function on both the development of ischemia-reperfusion injury(IRI) and graft rejection.In this review of current researches on allograft protection,we focused on the HO-1.We conjecture that HO-1 may link these two main factors affecting the prognosis of liver transplantations.In this review,the following aspects were emphasized:the basic biological functions of HO-1,itsroles in IRI and allograft rejection,as well as methods to induce HO-1 and the prospects of a therapeutic application of HO-1 in liver transplantation.

The role and modulation of autophagy in experimental models of myocardial ischemia-reperfusion injury

A physiological sequence called autophagy qualitatively determines cellular viability by removing protein aggregates and damaged cyto-plasmic constituents, and contributes significantly to the degree of myocardial ischemia-reperfusion （I/R） injury. This tightly orchestrated cata-bolic cellular‘housekeeping’ process provides cells with a new source of energy to adapt to stressful conditions. This process was first described as a pro-survival mechanism, but increasing evidence suggests that it can also lead to the demise of the cell. Autophagy has been implicated in the pathogenesis of multiple cardiac conditions including myocardial I/R injury. However, a debate persists as to whether autophagy acts as a protec-tive mechanism or contributes to the injurious effects of I/R injury in the heart. This controversy may stem from several factors including the va-riability in the experimental models and species, and the methodology used to assess autophagy. This review provides updated knowledge on the modulation and role of autophagy in isolated cardiac cells subjected to I/R, and the growing interest towards manipulating autophagy to increase the survival of cardiac myocytes under conditions of stress-most notably being I/R injury. Perturbation of this evolutionarily conserved intracellular cleansing autophagy mechanism, by targeted modulation through, among others, mammalian target of rapamycin （mTOR） inhibitors, adenosine monophosphate-activated protein kinase （AMPK） modulators, calcium lowering agents, resveratrol, longevinex, sirtuin activators, the proapoptotic gene Bnip3, IP3 and lysosome inhibitors, may confer resistance to heart cells against I/R induced cell death. Thus, therapeutic ma-nipulation of autophagy in the challenged myocardium may benefit post-infarction cardiac healing and remodeling.

EFFECT OF VASOPRESSIN ON DELAYED NEURONALDAMAGE IN HIPPOCAMPUS FOLLOWING CEREBRALISCHEMIA AND REPERFUSION IN GERBILS

Mongolian gerbils were used as delayed neuronal damage (DNDi animal models. At the end of 15Abstract:Mongolian gerbils were used as delayed neuronal damage (DND)animal models. At the end of 15 minute cerebral ischemia and at various reperfusion time ranging from 1 to 96 hours, the content of water and arginine vasopressin (AVP) in the CA1 sector of hippocampus were measured by the specific gravity method and radioimmunoassay. Furthermore, we also examined the effect of intracerebroventricular (ICV) injection of AVP, AVP antiserum on calcium, Na+, K+-ATPase activrty in the CA1 sector after ischemia and 96 hour reperfusion. The results showed that AVP contents of CA1 sector of hippocampus during 6 to 96 hour recirculation, and the water content of CA1 sector during 24 to 96 hour were significantly and continuously increased. After ICV inJection of AVP, the water content and calcium in CA1 sector of hippocampus at cerebral ischemia and 96 hour recirculation further increased, and the Na+, K+- ATPase activity in CA1 sector was remarkably decreased as compared with that of control. While ICV injection of AVP antiserum, the water content and calcium in CA1 sector were significantly decreased as com pared with that of control. These suggested that AVP was involved in the pathophysiologic process of DND in hippocampus following cerebral ischemia and reperfusion. Its mechanism might be through the change of intracellular action mediated by specific AVP receptor to lead to Ca ions over-load of neuron and inhibit the Na+, K+- ATPase activity , thereby to exacerbate the DND in hippocampus.

Intestinal ischemia and reperfusion induced second impairment of the rat heart

Objective: To study the changes of oxygen free radical, expression of apoptotic gene, ultrastructure of myocardial cell and second injury of the heart following the intestinal ischemia and reperfusion. Methods: Making the models of ischemia and reperfusion by clamping superior mesenteric artery, the concentration of NO and SOD in the blood was examined before clamping the artery and reperfusion for 0, 30, 60 min, 1, 3, and 7 d. The expression of Bax, Bal-2, and p53 in myocardial cell was studied by means of immunohistochemical SP method and the microstructure damage was observed under electron microscopy. Results: After clamping the superior mesenteric artery and reperfusion the concentration of NO increased continuously and reached a peak for reperfusion 7 d (P<0.01) but that of SOD decreased from 30 min to 7 d. The expression of Bax, p53 and Bcl-2 also increased obviously especially for reperfusion 30 min and 7 d following ischemia and reperfusion. After reperfusion for 30 min the positive cell rate of Bax, p53 and Bcl-2 was 53.6%, 45.9% and 67.9%, for reperfusion 7 d it was 52.4%, 43.4% and 31.9% respectively, but the positive cell rate of Bax and p53 was higher than that of Bcl-2. The result of electron microscopy observation showed mfofiliments breaked, dissolved and chromatin condensed. Conclusion: Intestinal ischemia and reperfusion of rat can induced the changes of oxygen free radical and the expression of apoptotic gene and second injury of myocardial cells.

Single-strand DNA damages and its relationship with morphological change of neurons at early stage of rat cerebral ischemia/reperf usion

Objective：To discuss the DNA-strand breaks at early stage of middle cerebral artery occlusion/reperfusion (MCAO/R). Methods: Neurons number and morphologic change were observed by Nissl stain method, and DNA strand breaks were in situ detected by using DNA polymerase- I Klenow fragment-mediat-ed nick end-labelling method (Klenow method). Results: Six hours after reperfusion, a few neurons in dam-aged regions appeared morphologic changes while a few Klenow-positive cells were detected (P<0. 01). Twenty-four hours after reperfusion lots of neurons showed morphologic change while the number of Klenow-positive cells immediately and remarkably increased (P<0. 01). Seventy-two hours after reperfusion the number of neurons decreased significantly and the number of Klenow-positive cells was also less than that in 24 h (P<0. 05). Conclusion: ① 24 h after reperfusion when the number of Klenow-positive cells reached peak value, DNA single-strand breaks (SSBs) took place in many Klenow-positive cells, and presumed that DNA SSBs might be an important step in DNA-damage procession which might be induced by free radicals. ② At the same time when lots of DNA SSBs were produced, many neurons in the damaged regions showed morphological change, which indicated that lots of neurons had already progressed to irreversible damages when DNA SSBs took place.

Use of autologous tissue engineered skin to treat porcine full-thickness skin defects

Objective. To explore a feasible method to repair full-thickness skin defects utilizing tissue engineered techniques. Methods： The Changfeng hybrid swines were used and the skin specimens were cut from the posterior limb girdle region, from which the keratinocytes and fibroblasts were isolated and harvested by trypsin, EDTA, and type II collagenase. The cells were seeded in Petri dishes for primary culture. When the cells were in logarithmic growth phase, they were treated with trypsin to separate them from the floor of the tissue culture dishes. A biodegradable material, Pluronic F-127, was prefabricated and mixed with these cells, and then the cell-Pluronic compounds were seeded evenly into a polyglycolic acid （PGA）. Then the constructs were replanted to the autologous animals to repair the full-thickness skin defects. Histology and immunohistochemistry of the neotissue were observed in 1, 2, 4, and 8 postoperative weeks. Results. The cell-Pluronic F-127-PGA compounds repaired autologous full-thickness skin defects 1 week after implantation. Histologically, the tissue engineered skin was similar to the normal skin with stratified epidermis overlying a moderately thick collageneous dermis. Three of the structural proteins in the epidermal basement membrane zone, type IV collagen, laminin, and type VII collagen were detected using immunohistochemicai methods. Conclusions ： By studying the histology and immunohistochemistry of the neotissue, the bioengineered skin graft holds great promise for improving healing of the skin defects.

Study of L-arginine-nitric oxide pathway in ischemia-reperfusion injured limbs in rats

Objective: To observe the change of nitric oxide (NO) levels in the blood and the morphological change of the muscles in the limbs of rats during the (IR) injury and after being intervened by L-arginine (L-Arg) and L-nitroarginine (L-NNA). Methods: Sixty-six male Sprague-Dawley (SD) rats were used and grouped into the normal controls, the sham injury controls, the IR injury group and the intervention groups (L-Arg group and L-NNA group). After 6 hours of ischemia, followed by reperfusion for 3, 12 or 24 hours, the samples in the IR injury group were obtained. The rats in the intervention groups were given L-Arg (100 mmol/L) and L-NNA (10 mmol/L), respectively, through the abdominal cavity. Then the anterior tibial muscle in the right limb was obtained for histological examination, the anterior tibial muscle in the left limb for ultrastructure observation and the blood for assay of NO in all the rats. NO was assayed by indirect measurement of NO 2 -/NO 3 - with Griess method. Results: There was no significant difference of NO between the normal controls and the sham injury controls (P> 0.05). But NO significantly decreased in the IR injury group (P< 0.01), and further decreased with reperfusion (P< 0.01) and reached the lowest point at 12 hours after reperfusion. The level of NO in the L-Arg group was significantly higher than that in the IR injury group (P< 0.01), but was not significantly different from that in the controls (P> 0.05). In the L-NNA group, NO decreased to the undetectable level (P< 0.01). Histological examination and ultrastructure observation showed the muscles were normal in the control groups. After 6 hours of ischemia, the skeletal muscles displayed injuries, and they were most severely injured after 12 hours of reperfusion. In the L-Arg group, the skeletal muscles were less injured, while in the L-NNA group, the injury was similar to that in the IR injury group. Conclusions: When the limbs of the rats sustain IR, NO in the blood decreases. Meanwhile, the muscles in the limbs are injured. When L-Arg is given, NO in the blood is restored and the muscles are protected. When L-NNA completely inhibits NO, no protection of the muscles is shown.