Objective To examine the chemo-preventive effect of cyclooxygenase-2(COX-2) inhibitor (celecoxib) in an animal model of stomach carcinogenesis. Methods Eighty-six male Wistar rats were divided into six groups. The rats were given water alone (group A, n=5), N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) (group B, n=16), 3 mg/kg of indomethacin daily (group C, n=16), 5 mg/kg of celecoxib daily (group D, n=17), 10 mg/kg of celecoxib daily (group E, n=16) or 20 mg/kg of celecoxib daily (group F, n=16). The animals in group B to F were given 10% sodium chloride (in the initial 6 weeks) and drinking water containing MNNG (100 ?g/ml) to induce gastric adenocacinoma. All animals received treatment for 40 weeks, and were sacrificed after death or at week 48. Gastric tumor was evaluated histologically. Results Among 86 rats, 26 rats died, and 60 rats completed the experiment. The incidences of gastric cancer were found 0 (0%) in group A, 12 (75.0%) in group B, 11 (68.8%) in group C, 12 (70.6%) in group D, 3(18.8%) in group E, and 5(31.3%) in group F. There were significant differences in tumor incidence (P=0.002), multiplicity (P=0.001) and volume (P=0.009) among different groups. When compared with group B, the group E had the greatest reduction in tumor incidence (P=0.004), tumor multiplicity ( P=0.006) and mean tumor volume (P=0.02). Treatment with indomethacin had no significant effect on tumor development. Conclusion While treatment with indomethacin had no significant effect on tumor development, treatment with celecoxib reduced gastric cancer incidence and growth in rats.

Objective To compare the vascularization of collagen scaffolds with or without growth factors and their efficacy on cardiac function in postinfarcted rats underwent surgical ventricular restoration.Methods Collagen scaffolds were activated with 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride chemistry (EDC) as control or continually covalently immobilized with vascular endothelial growth factor (VEGF) and VEGF + basic fibrohlast growth factor (bFGF) as experimental groups.Adult SD male rats underwent left anterior descending artery (LAD) ligation to generate transmural myocardial infarction(MI).Four weeks later,by echocardiography,rats with moderate scar size(25％-35％ akinetic area of freedom wall of left ventricle) were screened out,assigned into 3 groups randomly and received the surgical ventricular restocation (SVR).Then,cardiac function was measured by echocardiography at 1w,2w and 4w after patch implantation.At endpoint of study (4w after patch implantation),the rats were sacrificed and the hearts were harvested.Vascularization of patch were determined by capillary density (evidenced by vWFⅧ staining) or mature vessel density (evidenced by SMA staining) respectively.Results The general mortality of the animal model is 15％ (6/40).A significant improvement of cardiac function was observed in all animals at 1 w after patch implantation but that was better preserved in both cytokine-conjugated groups 4w later (control group vs.VEGF group,P ＜ 0.05,control group vs.VEGF + bFGF group,P ＜ 0.01).More capillaries were present in patch with growth factors (P ＜0.05),while significant functional vessel formation was observed only in VEGF + bFGF group (P ＜0.01 vs.control or VEGF group).Additionally,we identified a positive correlation between heart function and mature vessel density (P =0.0297,r2 =0.998).Conclusion The mechanical property of collagen scaffold can be effectively improved by EDC,the growth factors immobilized in scaffold were in favor of vascularization of patch,which may facilitate the preservation of cardiac function posterior to SVR.