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BACKGROUND/AIMS: Assessment of malignant potential in gastrointestinal stromal tumor (GIST) is still problematic. The maximum tumor diameter and the mitotic index are generally used as an index of malignancy of GISTs. The Ki-67 labeling index has recently been used as an index of cell growth. The aim of this study was to investigate the prognostic value of Ki-67 in GIST. METHODS: We retrospectively reviewed the medical records of 32 patients with GIST who underwent surgical resection at Inje University Seoul Paik Hospital. We analyzed their Ki-67 expression, histologic finding, and prognosis. RESULTS: According to the tumor size and mitotic count, 4 patients were classified as very low risk, 9 patients as low risk, 14 patients as intermediate risk and 5 patients as high risk. The average Ki-67 index was 5.56±4.48%. The median follow-up duration was 35.72±29.04 months, and local/distant recurrences were observed in 6 (18.7%) patients. The overall cumulative disease free survival rates in patients with Ki-67 index ≤5% at 1 year, 2 years, and 5 years were 100%, 100%, and 86%, respectively. The overall cumulative disease free survival rates in patients with Ki-67 index >5% were at 1 year, 2 years, and 5 years were 82.1%, 70.3%, and 46.9%, respectively. There was significant relationship between elevated Ki-67 and disease free survival rate (p=0.007). CONCLUSIONS: Our study suggests that Ki-67 index >5% confers a higher risk of relapse in patients with GIST. Future work should focus on standardization of Ki-67 assessment and specification of its role in making treatment decisions.

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PURPOSE: To evaluate the feasibility of using covered stents vs. bare stents in a model of central vein stenosis with an arteriovenous graft created to mimic the conditions in hemodialysis patients. METHODS: In 7 mongrel dogs, an expanded polytetrafluoroethylene-covered nitinol stent was placed in one common iliac vein and a bare stent was placed in the contralateral vein. Arteriovenous grafts were created bilaterally between the common femoral artery and vein to induce endothelial damage. Neointima formation in the covered stents was compared to the bare stents at 12 weeks using microscopy and histochemical staining. RESULTS: Two dogs were excluded due to thrombosis and infection of the arteriovenous grafts, but all stents in the remaining 5 dogs were patent. Smooth, complete neointimal coverage was observed on the inner surface of all the covered stents without intraluminal thrombus. In contrast, incomplete neointimal coverage was seen in all bare stents, with small focal thrombi adhering to the neointima on 3 bare stents. Focal nodular neointimal hyperplasia with denudation of the endothelium was observed in only 2 bare stents. Mean neointimal thickening was significantly greater in the covered stents. Eccentric neointimal thickening was observed at the inflow and outflow segments of both types of stents. CONCLUSION: Covered stents are technically feasible for the treatment of central vein stenosis, and they demonstrate complete, smooth neointimal coverage in normal central veins, but they also display greater neointimal thickening than bare stents.

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PURPOSE: To evaluate the feasibility of transarterial prostate embolization for reducing the volume in hormone-induced canine prostate hyperplasia. MATERIALS AND METHODS: Nine beagle dogs were included in this study. Prostate hyperplasia was induced by administering dihydrotestosterone and beta-estradiol. The hormones were given for 12 weeks in group A (n = 4) and 24 weeks in group B (n = 5). Twelve weeks after initiating the hormone treatment, two animals in group A and three in group B underwent prostate embolization with polyvinyl alcohol (PVA) particles. The volume of each prostate was measured three times with magnetic resonance (MR) imaging: once before hormone treatment and at 12 and 24 weeks after initiation of hormone administration. The prostates and bladders were harvested after the third MR study and were grossly and microscopically evaluated. RESULTS: The mean volume of the prostate increased by 156.13% +/- 110.01% in the nine dogs after 12 weeks of hormone administration. In group A (n = 4), the third MR study showed a 67.74% mean decrease in prostate volume in nonembolized dogs and an 81.04% mean decrease in embolized dogs compared with the second MR study. In group B (n = 5), the mean increases in prostate volume between the second and third MR studies were 40.79% in embolized dogs (n = 3) and 75.15% in nonembolized dogs. There was no gross or microscopic change in the bladders except for a focal hemorrhage in one specimen. CONCLUSIONS: Transcatheter arterial embolization is feasible for reducing prostate volume without serious complications in hormone-induced canine prostate hyperplasia.

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Kidney donation from female donors to male recipients has been reported to be associated with decreased allograft survival. Whether there was a gender-related inadequacy between donor nephron supply and recipient functional demand was investigated in this study. One hundred ninety-five living donor kidney transplant recipients that had neither ischemic injury, episode of rejection, nor any complication were included. Weights and heights of both donors and recipients were recorded to calculate body surface area, lean body weight, and body mass index. The donated kidney was weighed just after cold flush, and the recipient's serum creatinine (Scr) was measured on a daily basis post-operatively. When the recipient's Scr reached the baseline, a 24-h urine was collected for the amount of proteinuria (Upr), creatinine excretion (Ucr) and creatinine clearance (Ccr) calculation. The effect of donor and recipient gender was analysed by independent sample t-test. On average, male donors and recipients were heavier and taller than females. However, the mass of kidneys donated from men and women were not statistically different. The gender-related differences in post-transplant Scr and Ucr of recipients were associated with the differences in the parameters of metabolic demands of recipients rather than with the weight of implanted kidney (renal mass supply) or with pre-operative renal functions of donors (functional supply). The early graft function is not determined by donor gender. The effect of recipient gender on the graft function depends on the metabolic demands, which are higher in male recipients.

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