AIM:To study phenotypic changes of vascular smooth muscle cells (VSMC) in abdominal aortic aneurysmal (AAA) pathogenesis. METHODS: Tissue samples of human infrarenal aneurysmal and normal aorta(NA), and arterial occlusive diseases(AOD) were evaluated. Monoclonic antibodies of ?-smooth muscle actin(?-SMA), desmin and smooth muscle myosin heavy chain isoforms (SM1, SM2 and SMemb) were used in immunohistochemistry to determine VSMC isoforms. Immunohistochemical results were analyzed with the use of computer-generated image technique. Ultrstructures of VSMC in three tissues above were observed by electron microscope. RESULTS: In control AOD and NA, VSMC in the media were strongly immunostained for ?-SMA, desmin, SM1 and SM2. Immunoreactivity for SMemb was faint or weakly positive in AOD, but negative in NA. In AAA,the balance shifts to SMemb predominance with suppressed ?-SMA, SM1 and SM2 and negative desmin, while in ruptured aneurysmal walls, the expression of SM2 and SMemb were decreased compared with the non-ruptured aneurysmal walls. CONCLUSION:Phenotypic changes of VSMC are concerned with abdominal aortic structure lesion and remodeling, which contributes to AAA formation and development.

Extracellular matrix plays an important role in maintaining organic structure and function, cellular proliferation and differentiation of normal aorta. Extracellular matrix proteolysis and remodeling of aortic wall resulting from degradation of matrix proteins characterize abdominal aortic aneurysm (AAA). Matrix metalloproteinase and its inhibitor have been implicated as potentially important in this disease, and MMP/TIMP ratios may be the key of AAA formation and development. [

Dynamic interactions between cells and underlying extracellular matrices are crucial for development, maintenance of cellular function, and response of tissure to injury and infection. Heparan sulfate proteoglycans(HSPG)are found in extracellular matrices and on the surface of most nuclrarated cells, and play critical roles in cell-cell and cell-matrix signal transduction by binding many molecules, such as growth factors and cytokines. Most of the biological properties of HSPG are conferred by heparan sulfate side chains, which can be degraded by heparanase. Changes of heparanase expression and activity may affect the biological processes above, which enables extravasation of inflammation cells, metastasis and neoangiogenesis of tumor cells invasion.

Objective To evaluate heparanase inhibitor PI-88 in the inhibition of abdominal aortic aneurysm(AAA) formation. Methods A guinea pig-to-SD rat transplantation model of AAA was established for the observation of therapeutic effects of PI-88 given by continuously administration within 4 weeks after abdominal aortic transplantation. Abdominal aortic diameter, the degree of inflammatory infiltration, microvessel density and the expression of heparanase were determined by immunohistochemistry and Northern blot analysis. Results In contrast to the positive controls, the diameter and inflammatory cell infiltration of graft decreased remarkably after administrating PI-88, and the expression of heparanase and microvessel density decreased accordingly, although still upregulated when compared with negative control. Conclusions PI-88 could prevent formation of AAA by inhibiting heparanase activation.

To investigate the contents and distribution of matrix metallproteinases(MMP) in abdominal aortic aneurysm(AAA) on protein level, forty male Wistar rats were randomly divided into two groups, the rats of experimental group were perfused with pancreatic elastase in the isolated abdominal aorta to construct the model of AAA. Laparotomy was preformed on the 14th day after operation, the aortas were measured and harvested. The rats of control group were operated with the aortas harvested immediately. Immunohistochemical staining and computer image analysis were performed to analyze the contents and distribution of MMP 2 and MMP 9. The aortic diameter progressed to aneurysmal dimension in the experimental group. Immunohistochemistry study revealed that the MMP contents in AAA exceeded that in normal aorta obviously. The MMP 2 cotents in AAA tunica media were higher than MMP 9. It is suggested that MMP 2 plays the main role in extracellular matrix degradation of AAA tunica media.

To explore the pathogenesis and treatment of fever, leukocytosis and thrombocytopenia after endovascular graft exclusion for aortic aneurysm or aortic dissection, 67 patients with infrarenal aortic aneurysm (38) and thoracic aortic dissection (29),were studied,and then received successful endovascular graft exclusion with Dacron covered stent grafts. Sepsis syndrome evaluation (physical examination, analysis of peripheral blood WBC, platelet and urine, chest radiograph, urine and blood cultures) was performed for all patients with postoperative temperature(T) higher than 38 5℃. Fever, leukocytosis and thrombocytopenia in peripheral blood were found in most patients, whose T, WBC and platelet returned to normal between 1 and 2 weeks. Sepsis evaluations failed to identify any source of infection in all patients. These results showed that fever and leukocytosis after endovascular stent graft repair for aortic aneurysm are resulted from systemic inflammatory response syndrome.

To investigate the prevention and management of postoperative complications of lower extremity amputation for arterial occlusive diseases, a retrospective analysis was made in 18 lower extremity amputations which were performed on 14 patients from Jan 1996 to Dec 1999. The mean age of the patients was 72. Before opeoation,78 6% of the patients were complicated with coronary artery disease, 69.9% with high blood pressure and 78.6% with diabetes mellitus, 43.4% with vascular reconstruction history. 6 above the knee amputations, 7 below the knee amputations, 1 hemiterpene amputation and 4 amputations of the toes were performed. Postoperative myocardial infarction occarred in 2 cases, gangrene of the stump in 3 cases and infection in 1 case, the total incidence rate of complication was 33%. The results showed that lower extremity amputation is not a complex operation, but preoperative estimation of the level of amputation and postoperative intensive care can reduce the postoperative rate of complication.

Colonic ischemia is a well documented complication of abdominal aortic reconstruction. In this retrospective study of abdominal aortic aneurysm patients undergone endovascular graft exclusion, the incidence and management of this complication were investigated. From Mar 1997 to Apr 2000,among the 40 patients who received elective endovascular graft exclusion for,infrarenal abdominal aortic aneurysm the bilateral hypogastric artery was retained in 30 patients, the unilateral hyogastric artery was retained in 10 patients. One patient had lower abdominal pain on the 28th day after operation, CTA showed the bilateral hypogastric artery occlusion, the symptoms were relieved after drug treatment. Retaining unilateral hypogastric artery can prevent the colonic ischemia after endovascular graft exclusion for abdominal aortic aneurysm, the chronic colonic ischemia secondary to bilateral hypogastric artery occlusion can be relieved by effective drug treatment.

To compare the effects of open surgery (OS) and endovascular graft exclusion (EVGE) for abdominal aortic aneurysms on the liver and renal functions, the serum total protein, albumin, globulin and the ratio of A/G of 57 patients with alodominal aortis aneurysm were analyzed before and after the two operations.The results showed that the serum total protein,albumin,globalin and the ratio of A/G were signifcantly decreased in the open surgery group, while remarkabe decrease was found in globulin but no significant change in the ratio of A/G in the EVGE group.Creatinine and urea introgen were significantly decreased in the open surgery graup and remained normal in the EVGE group.It is suggested that the effect of EVGE on the liver and renal function is much less than traditional(open) surgery.

To investigate the diagnosis and treatment of Stanford B thoracic aortic dissection eomplicated with renal ischemia, 29 cases of Stanford B thoracic aortic dissection admitted from January 1996 to April 2000 were retrospectively studied. Three of them had renal ischemia secondary to aortic dissection (2 acute,1 chronic). One patient in acute stage died 3 days after onset, the other patient in acute stage complicated with bilateral lower extremity ischemia was treated with fenestration of intimal flap, and the symptom was relieved. The patient in chronic stage was treated with endovascular graft exclusion for aortic dissection and the renal ischemia was relieved because of the restored true lumen blood. The results showed that palliative bypass helps relieve symptoms and improve survival rate. For the chronic aortic dissection complicated with renal ischemia, endovascular graft exclusion can restore the true lumen blood and relieve renal ischemia.