Objective To study the effects of D-Ala2-Leu5-enkephalin(DADLE) preconditioning on rabbit donor heart preservation and protective mechanism.Methods 24 rabbits were randomly divided into 4 groups. In group B, after preconditioning with DADLE(1mg?kg -1 ), the donor hearts were then arrested and preserved with Krebs-Henseleit buffer at 4℃ for 4h,and group A without conditioning as controls. Then the donor hearts were transplanted into the abdomen of recipient rabbits. Recovery situation of contraction of the donor heart was compared. The left ventricular tissues were obtained from the donor hearts after 2h of transplantation.The contents of free radicals and ATPase activity were determined and cardiac ultrastructure were observed.Results After 4h cold storage, the heart undergoing DADLE preconditioning in group B showed better recovery of left ventricular development pressure (LVDP).The activity of sodium-potassium ATPase in group B were higher than that in group A. DADLE increased free radical production 2-fold versus group A. Group B showed slighter injury in transmission electron microscopy observation than that in group A.Conclusion Our study demonstrated opioid preconditioning has protective function to rabbit heart injury caused by long term cold storage. The protective mechanism maybe related to increase of free radical content.

Objective To investigate the peri-nasopharyngeal invasion patterns of nasopharyngeal carcinoma (NPC) on MRI and its relationship with tumor staging. Methods One thousand five hundred and seventy-three patients with newly diagnosed NPC which were histo-pathologically proved were retrospectively studied. The MRI manifestations and invasion patterns of the NPCs were elevated according to the 2008 Tstaging system of NPC. Z test was used to analyze the rate of adjacent structures invasion in NPCs. Results The structures invaded by NPCs included pharyngobasilar fascia in 1299 cases (82. 58% ); parapharyngeal space, 1090 ( 69. 29% ); nasal cavities, 304 ( 19. 33% ); oropharynx, 49 ( 3. 12% ); carotid space,514(32. 68% ); medial pterygoid muscle, 661 (42. 02% ); lateral pterygoid muscle, 210( 13. 35% ); skull base bones, 943(59. 95% ); cranial nerves, 630(40. 05% ) and paranasal sinuses, 242 ( 15.38% ). The T-stage distribution was T1, 242 cases ( 15.38% ); T2, 288 ( 18. 31% ); T3, 410 (26. 06% ) and T4,633 (40. 24% ). Among the cases with nasal cavities invasion, 90. 46% (275/304)showed the involvement of the structures seen in T3 or T4 stage, which was found in all cases with oropharynx invasion. In addition,69. 14% (457/661) of cases with medial pterygoid muscle invasion and 92. 15% (223/242) of cases with paranasal sinuses invasion showed the involvement of structures seen in T4 stage. As for the invasion patterns of NPC, the lateral invasion of pharyngobasilar fascia was more frequent than upward invasion of skull base (Z = 14. 025, P ＜ 0. 01 ) and downward invasion of oropharynx ( Z = 45.032, P ＜ 0. 01 ), and the downward invasion of oropharynx was less frequent than upward invasion of skull base ( Z = 34. 301, P ＜ 0. 01 ) and forward invasion of nasal cavities ( Z = 14. 404, P ＜ 0. 01 ). Conclusion NPC has a predilection of lateral invasion rather than upward and downward invasion, and its upward and forward invasion are more common than downward invasion.