Objective To explore the risk factors for recurrent （≥ 2 times） pneumonia in elderlykidney transplant recipients after surgery. Methods Retrospective analysis was performed from the clinical data of 119 elderly kidney transplant recipients who underwent kidney transplantation at the Eighth Medical Center of the People's Liberation Army General Hospital from January 2010 to January 2024. According to whether pneumonia occurs repeatedly （≥ 2 times） after kidney transplantation， elderly recipients were divided into two groups， with 11 cases in the recurrent pneumonia group and 108 cases in the non-recurrent pneumonia group. Relevant clinical data were compared between the two groups， including the general basic information of the recipient （gender， age， height， weight， smoking history，etc.）， as well as the relevant clinical data （the time of dialysis before kidney transplantation， the maintenance treatment plan of immunosuppressant after surgery， whether there was delayed recovery of kidney function after transplantation， whether there was a decrease in white blood cells after transplantation， serum creatinine level at discharge， whether there was diabetes before and after surgery， and whether there was viral hepatitis B infection， etc.）. We conducted univariate analysis and multivariate logistic regression analysis to explore the risk factors for recurrent pneumonia in elderly kidneytransplant recipients after surgery. Results The incidence of recurrent pneumonia in elderly kidney transplant recipientsafter surgery was 9.24% （11/119）， and one patient in the case group died from severe pneumonia， with a mortality rate of 9.1% （1/11）. Smoking history （OR ＝ 13.15，95% CI ＝ 2.406 ～ 71.91，P ＝ 0.003） and postoperative leukopenia （OR ＝ 6.050，95% CI ＝ 1.248 ～ 29.32，P ＝ 0.025） were risk factors for recurrent pneumonia in elderly kidney transplant recipients. Conclusion Smoking history and postoperative leukopenia increase the risk of recurrent pneumonia in elderly kidney transplant recipients. So we should strengthen postoperative health education for elderly kidney transplant recipients， encourage smoking cessation， and prevent and treat postoperative leukopenia. 

Objective To explore the effect and preliminary mechanism of plant extract ursolic acid（UA）inreducing hepatic ischemia/reperfusion injury（HIRI）. Methods C57 male mice were divided into sham operation group，sham operation +UA group，HIRI group，HIRI low-dose group and HIRI high-dose group. The analysis and validationwere carried out by methods such as animal experiments，network pharmacology and molecular biology. Results Animal experiments showed that UA significantly reduced the activities of AST and ALT in serum of HIRI mice. Target genescorresponding to HIRI and ursolic acid were obtained by TCMSP，Pharm Mapper，Swiss Target Prediction，GeneCards and other databases，and key target genes were obtained by DAVID，STRING and Cytoscape. They were PPARG （peroxisome proliferator-activated receptor gamma，PPARG），

MAPK3（mitogen-activated protein kinase 3，MAPK3） and PTGS2（prostaglandin G/H synthase 2，PTGS2）. Finally，PTGS2 was identified as the hub target gene in this study according to the molecular docking score and the number of hydrogen bonds binding between receptor and ligand. Compared with Sham operation group，PTGS2 was highly expressed in HIRI group（P ＜ 0.01）. Compared with HIRI group，the expression of PTGS2 in HIRI + LUA and HIRI + HUA groups was significantly decreased （P ＜ 0.01）. Conclusion UA can regulate the protective effect of PTGS2 on hepatic ischemia reperfusion injuryin mice. Thisstudy providesa reference for clinical development of new drugsto interveneHIRI.

Objective Establish model of abdominal heterotopic heart transplantation in mice and summarize the experience to provide animal model support for further study of organ transplantation immunology. Methods Inbred BALB/c（n ＝ 30）and C57BL/6（n ＝ 30）mice were selected as donors，and inbred BALB/c（n ＝ 60）mice were used as recipients. The ascending aorta of the donor was anastomosed to the abdominal aorta of the recipient，and the pulmonary artery of the donor was anastomosed to the inferior vena cava of the recipient respectively to establish the heterotopic heart transplantation model. The survival time and the rejection of grafts were observed postoperatively. Results The successful rate of transplantation was 85%（51/60）. The donoroperation time was（7.0±1.0）min，and the recipient operation time was（60±10）min. The vascular anastomosis time was（25±3.0）min. After the transplantation，no immunosuppressive agent was used，and the survival time of the graft was（7.6±0.9）d. The graft on the fifth day，the seventh day showed typical rejection by histopathology. Conclusion Skilled microsurgical techniques and timely management of surgical complications are key to the successful establishment of abdominal heterotopic heart transplantation in mice. 

Objective To summary and discuss the successful diagnosis and therapy to antibody mediatedrejection（AMR）post pediatric ABO-incompatible liver transplantation. Methods Abnormal graft function was found within 1 month after living donor liver transplantation. Then，liver biopsy were performed twice and human lymphocyte antigen（HLA）antibodies were detected. Results Acute rejection was revealed in both liver biopsies，intravenous methylprednisolone was used for anti-rejection therapy. AMR was diagnosed by positivity of C4d and strong expression of donor specific antibody（DSA）subsequently. The effective therapies were performedincluding combination of plasmapheresis and intravenous immunoglobulin（IVIG）on alternate days for 1 week，followed by single rituximab. Meanwhile，mycophenolate mofetil was used at the beginning. The graft function recovered to normal with decreasing of DSA. The patient has been followed for more than 2 years with well graftfunction. Conclusion AMR could be induced by ABO incompatible pediatric liver transplantation with serious consequence. AMR can be cured by conservative therapies and normal graft function could be achieved.