Abstract: Objective To examine the cell viability and hemodynamic functions of the stented homograft valves preserved in liquid nitrogen. Methods Cell viability of the stented homograft valve preserved in liquid nitrogen after 3 months of preservation (experimental group，n=6) was examined using flow cytometer. Fresh homografts served as control group (n=6). We prepared three sorts of stented homograft valve(21#, 23#, 25#) preserved by liquid nitrogen. In vitro pulsatile flow tests were performed on valves of two groups. Effective opening area EOA),transvalve pressure gradient and regurgitation ratio were recorded at various flow volume, and compare with Perfect bioprosthetic valve. Results The results revealed that the death ratio of endothelial cell was 10.24%±1.71% in the experimental group, and 9.09%±2.72% in the control group (P=0.441). The death ratio of smooth muscle cell was 8.76%±1.82% in the experimental group, and 7.84%±0.59% (P=0.178) in the control group. The death ratio of total cell was 8.79%±1.44% in the experimental group, and 7.40%±0.49% in the control group (P=0.072). There were no significantly differences between two groups. The transvalve pressure gradient of two groups of valve depended on the flow volume, and increased with the flow volume increasing. The transvalve pressure gradient of the stented homograft valve was higher than that of Perfect valve. Regurgitation ratio of the stented homograft valve was bigger than Perfect valve’s. EOA had an increasing character when flow volume increased. EOA of the stented homograft valve was smaller than that of Perfect valve’s. Conclusion Liquid nitrogen can offer the benefit of cell viability of the stented homograft bioprosthetic valves. The stented homograft valve has salisfactory hemodynamic functions.
目的 探讨手术切除联合液氮冷冻治疗结膜鳞状细胞癌的临床效果。 方法 分析1998年-2008年收治的21例眼睑结膜鳞癌患者的临床资料。对肿瘤局限在眼球结膜和部分穹窿结膜受侵犯者行单纯手术切除联合液氮冷冻治疗；部分或全部结膜及眼睑受侵犯者行局部肿瘤切除联合眼睑重建及液氮冷冻治疗；眼睑和球结膜广泛受累，无法进行眼睑重建者行眼眶内容物剜除术。 结果 21例中，7例行单纯肿瘤切除合并冷冻治疗，其中5例痊愈，2例复发；10例行局部肿瘤切除并进行眼睑重建，其中7例痊愈，3例复发，复发病例作眶内容摘除；4例肿瘤侵犯范围较宽而无法保留眼球者行眼眶内容物摘除。术手3例死于肝肺转移。 结论 眼睑结膜鳞状细胞瘤的外科手术切除是唯一有效的方法，眼睑重建视肿瘤侵犯范围而定，冷冻治疗作为辅助治疗可提高疾病的治愈率。
In the present study, the performance of the liquid nitrogen frozen and thinned bovine pericardium was studied and compared with the porcine pericardium. The microstructure and mechanical properties of the bovine pericardium were observed and tested by hematoxylin-eosin (HE) staining and tensile test respectively. In all conditions, porcine pericardium was selected as a control group. The results showed that there was little difference in the performance of bovine pericardium after being frozen by liquid nitrogen. The secant modulus and ultimate strength of the thinned bovine pericardium were similar to those of porcine pericardium, however, the elastic modulus was a little higher than porcine pericardium. The study suggested that the performance of the thinned bovine pericardium was similar to those of porcine pericardium. It was easy for the thinned bovine pericardium to obtain a relatively ideal thickness and expected performance, therefore, the thinned bovine pericardium can be used as the materials of transcatheter aortic valve leaflets.