如何正确运用Z检验——总体方差已知时两算术均值比较一般差异性Z检验及SAS实现

本文的目的是介绍总体方差已知时两算术均值比较一般差异性Z检验及SAS实现。首先，介绍了选用Z检验的前提条件；其次，介绍了单组设计和成组设计条件下进行均值比较的Z检验统计量，并介绍了上单侧检验、下单侧检验和双侧检验时所对应的拒绝域；最后，结合两个实例，基于SAS软件实现3种Z检验，对输出结果做出了解释。并针对如何合理选择单侧检验还是双侧检验给予说明。     

Cell-free DNA in the surveillance of heart transplant rejection

BackgroundCirculating cell-free deoxyribonucleic acid (cfDNA) is promptly materializing as a highly useful tool for the surveillance of solid-organ transplant rejection. Donor-specific fraction (DF) cfDNA is a potential marker of selective donor organ injury. It is emerging as a promising analytical target in the near future. The aim of this systematic review is to throw light on the importance of cfDNA and future perspective in detecting acute rejection in heart transplantation.MethodsAn exhaustive search was carried out for this review article on the basis of literature available including scientific databases of PubMed, Embase, and ClinicalTrials.gov. The search engines were systematically explored using the search terms “cell free DNA,” “Heart transplant,” and “Rejection” from inception until August 2020, and narrative analysis was accomplished. Majority of the studies described endomyocardial biopsy-proven acute rejection as reference standard.ResultsAfter initial screening of 331 articles, 11 studies were included and discussed in detail in the present review article. Majority of the studies showed prospective designs. A firm correlation was noted between acute rejection (identified on endomyocardial biopsy) and cfDNA levels by most of the studies.ConclusionscfDNA is a promising tool to replace repeated biopsies to detect rejection. The development in the area of digital droplet polymerase chain reaction and massive parallel sequencing, along with the overall reduction in cost of sequencing with its automation, has helped establish its role in the transplant population.     

Validation of donor fraction cell-free DNA with biopsy-proven cardiac allograft rejection in children and adults

ObjectivesDonor-specific cell-free DNA shows promise as a noninvasive marker for allograft rejection, but as yet has not been validated in both adult and pediatric recipients. The study objective was to validate donor fraction cell-free DNA as a noninvasive test to assess for risk of acute cellular rejection and antibody-mediated rejection after heart transplantation in pediatric and adult recipients.MethodsPediatric and adult heart transplant recipients were enrolled from 7 participating sites and followed for 12 months or more with plasma samples collected immediately before all endomyocardial biopsies. Donor fraction cell-free DNA was extracted, and quantitative genotyping was performed. Blinded donor fraction cell-free DNA and clinical data were analyzed and compared with a previously determined threshold of 0.14%. Sensitivity, specificity, negative predictive value, positive predictive value, and receiver operating characteristic curves were calculated.ResultsA total of 987 samples from 144 subjects were collected. After applying predefined clinical and technical exclusions, 745 samples from 130 subjects produced 54 rejection samples associated with the composite outcome of acute cellular rejection grade 2R or greater and pathologic antibody-mediated rejection 2 or greater and 323 healthy samples. For all participants, donor fraction cell-free DNA at a threshold of 0.14% had a sensitivity of 67%, a specificity of 79%, a positive predictive value of 34%, and a negative predictive value of 94% with an area under the curve of 0.78 for detecting rejection. When analyzed independently, these results held true for both pediatric and adult cohorts at the same threshold of 0.14% (negative predictive value 92% and 95%, respectively).ConclusionsDonor fraction cell-free DNA at a threshold of 0.14% can be used to assess for risk of rejection after heart transplantation in both pediatric and adult patients with excellent negative predictive value.     

不同血浆置换方式在免疫性疾病及肾移植急性排斥反应中的应用分析

目的探究不同血浆置换方式在免疫性疾病及肾移植急性排斥反应中的应用,为临床实践提供理论依据。方法本研究纳入2016年4月至2018年3月西安市中心医院收治的100例免疫性疾病及肾移植急性排斥反应患者,分为对照组和研究组,每组各50例,对照组给予单重滤过血浆净化,研究组给予双重滤过血浆置换,对比两组患者生化指标、治疗情况、不良反应、预后情况,进行统计学分析。结果研究组治疗后的血浆免疫球蛋白G和抗肾小球基底膜抗体水平低于对照组,差异具有统计学意义(P<0.05)。研究组不良反应发生率明显低于对照组,差异具有统计学意义(P<0.05)。研究组患者住院时间、治疗费用均优于对照组,差异具有统计学意义(P<0.05)。研究组患者肾功能恢复率明显高于对照组,差异具有统计学意义(P<0.05)。结论免疫性疾病及肾移植急性排斥反应患者实施选择性双重滤过血浆净化,有效改善血液免疫球蛋白G与抗肾小球基底膜抗体水平,缩短治疗时间,提高治疗有效率,降低不良反应,治疗效果显著。     

超声检查在胰肾联合移植术后监测中的应用价值初探

目的初步探讨超声检查在胰肾联合移植(SPK)术后监测中的应用价值。 方法回顾性分析青岛大学附属医院2019年8月至11月完成的5例行SPK供、受者超声检查资料。5例供者术前行常规二维超声检查,评估肾脏和胰腺大小、内部回声。供器官获取后依次行肾移植和胰腺移植。术后1周内每天行超声检查1次,1周后每3天1次,1个月后每2个月1次,或根据病情需求行超声检查。采用重复测量资料方差分析比较SPK移植前、移植后第1、7天和第1个月移植胰腺和肾脏大小以及移植后第1、3、7天及第1个月移植胰腺及肾脏内动脉收缩期最大流速(PSV)、阻力指数(RI),进一步两两比较采用LSD法。P<0.05为差异有统计学意义。 结果常规二维超声显示术后1周内移植胰腺形态饱满,实质回声偏低、均质,胰管无扩张;移植肾形态饱满,皮质回声均匀,皮髓质分界清晰,集合系统无分离。5例SPK受者术后第1天移植胰腺胰头、胰体和胰尾以及肾脏长径、前后径和左右径均大于移植前,差异均有统计学意义(P均<0.05);术后第1个月移植胰腺胰头、胰体和胰尾以及肾脏长径均小于术后第1天,差异均有统计学意义(P均<0.05)。移植术后1周内彩色多普勒血流显像检查示胰腺内动、静脉血流显示较好,胰腺内动脉PSV为16.6～37.2 cm/s,RI为0.52～0.70。5例移植胰腺中4例门-腔静脉血流显示良好,频谱呈双相波或三相波等体静脉频谱特征。1例术后门-腔静脉吻合口显示欠清,超声造影检查示动脉期移植胰腺肠系膜上动脉、脾动脉及实质内小动脉分支顺次清晰显影,静脉期门-腔静脉、脾静脉显影,实质内未见异常灌注区。5例移植肾脏三级血流显示清晰,肾动脉PSV为24.2～123.0 cm/s,RI为0.55～0.81。5例受者术后第1、3、7天和第1个月移植胰腺内胰头动脉和胰体尾动脉以及移植肾内肾叶间动脉、肾段动脉和肾门动脉PSV、RI差异均无统计学差异(F＝0.182、0.953、1.321、1.867、2.121和1.588、0.544、3.902、2.752、0.956,P均>0.05)。1例维吾尔族男性受者术后第22天怀疑发生急性排斥反应,予甲泼尼龙冲击治疗后恢复正常。截至2020年2月,5例受者术后均恢复良好,移植肾脏与胰腺功能良好,肾功能及血糖水平均恢复正常。 结论超声可以作为SPK术后动态监测的首选影像学检查方法,了解移植物大小、体积、内部回声和血流动力学等情况,对早期发现术后并发症有重要价值。     

小肠移植术后慢性移植物失功1例报道及文献复习

目的探讨小肠移植术后慢性移植物失功(chronic graft dysfunction,CGD)的诊断及治疗。方法报道国内首例同种异体小肠移植患者术后CGD的临床资料,复习相关文献。结果患者因"门静脉血栓、脾静脉血栓致肠系膜血栓"切除了大部分小肠,后行同种异体小肠移植术。术后长期服用他克莫司(FK506),屡次发生排斥反应。术后3次因"小肠狭窄、不全性肠梗阻"行"小肠节段切除吻合术"。其中术后576d第3次出现肠梗阻,予经皮内镜下胃空肠造瘘术胃肠减压等治疗,确定移植肠不可逆性失功后行移植小肠切除术。结论 CGD治疗困难,预后不佳,预防胜于治疗。在确诊CGD不可逆后应尽快切除移植小肠,挽救患者生命,有条件应尽快安排再次移植。     

Changes in myocardial electrical impedance in human heart graft rejection

BACKGROUND: Monitoring of post-transplant heart rejection is currently based on endomyocardial biopsy analysis. This study aimed to assess the effects of heart graft rejection on myocardial electrical impedance. METHODS AND RESULTS: Twenty-nine cardiac transplant patients and 9 controls underwent measurement of myocardial electrical impedance using a specifically designed amplifying system. The module and phase angle of myocardial impedance were measured. Histopathological rejection grading was performed according to ISHLT classification. Fifty impedance tests were performed in transplanted patients. Myocardial impedance (Z) was higher in controls than in transplanted patients (p<0.001) and followed a progressive decline at increasing current frequencies (p<0.001). Likewise, the phase angle of impedance in controls ranged from positive values at low frequencies to negative values at higher frequencies (from 2.5+/-0.9 degrees at 10 kHz to -3.8+/-2.1 degrees at 300 kHz, p<0.001). Rejection was associated with a significant decrease in myocardial impedance (Z) (15+/-6.6 Omega in grade 0, 13+/-6.0 Omega in grade 1A, and 3.3+/-0.9 Omega in grade 3A at 10 kHz, p<0.003). CONCLUSIONS: Mild degrees of cardiac graft rejection are associated with significant changes in myocardial electrical impedance in transplant patients. Further clinical investigation is warranted to assess the potential of cardiac impedance to detect heart graft rejection.     

常山酮对大鼠心脏移植急性排斥反应的抑制作用

目的:研究常山酮(HF)对大鼠异基因心脏移植急性排斥反应的影响及相关机制。方法:SPF级近交系Wistar雌性大鼠30只,SD雌性大鼠60只,随机分为3组行颈部心脏移植手术:同系对照组15对(供、受体均为SD大鼠,术前第1天及术后均用生理盐水灌胃),排斥组15对(供体为Wistar大鼠,受体为SD大鼠,术前第1天及术后均用生理盐水灌胃)及HF治疗组15对(供、受体同排斥组,术前第1天及术后均用HF溶液灌胃)。移植后第3,5,7天每组各处死5只受体大鼠,留取移植心行组织病理学及分子生物学检测。结果:与排斥组相比,HF治疗组移植心存活时间延长,免疫排斥反应减轻,血清中白细胞介素-17(IL-17)呈低水平,供心心肌组织中相关细胞因子白细胞介素-6(IL-6)、白细胞介素-8(IL-8)及肿瘤坏死因子-α(TNF-α)呈低表达,具有统计学差异。结论:常山酮可以有效抑制大鼠心脏移植模型体内由于急性排斥反应引起的多种促炎性细胞因子的异常升高,具有抗急性移植排斥反应的潜能,其机制可能与抑制了Th17分泌IL-17减少相关。