Bryostatin-1 Attenuates Ischemia-Elicited Neutrophil Transmigration and Ameliorates Graft Injury after Kidney Transplantation.

Ischemia reperfusion injury (IRI) is a form of sterile inflammation whose severity determines short- and long-term graft fates in kidney transplantation. Neutrophils are now recognized as a key cell type mediating early graft injury, which activates further innate immune responses and intensifies acquired immunity and alloimmunity. Since the macrolide Bryostatin-1 has been shown to block neutrophil transmigration, we aimed to determine whether these findings could be translated to the field of kidney transplantation. To study the effects of Bryostatin-1 on ischemia-elicited neutrophil transmigration, an in vitro model of hypoxia and normoxia was equipped with human endothelial cells and neutrophils. To translate these findings, a porcine renal autotransplantation model with eight hours of reperfusion was used to study neutrophil infiltration in vivo. Graft-specific treatment using Bryostatin-1 (100 nM) was applied during static cold storage. Bryostatin-1 dose-dependently blocked neutrophil activation and transmigration over ischemically challenged endothelial cell monolayers. When applied to porcine renal autografts, Bryostatin-1 reduced neutrophil graft infiltration, attenuated histological and ultrastructural damage, and improved renal function. Our novel findings demonstrate that Bryostatin-1 is a promising pharmacological candidate for graft-specific treatment in kidney transplantation, as it provides protection by blocking neutrophil infiltration and attenuating functional graft injury.

Merendino Resection vs. Transhiatal Gastric Conduit After Resection of the Cardia and the Gastroesophageal Junction.

BACKGROUND: Reconstruction after combined cardia resection and removal of the gastroesophageal junction can be carried out by the Merendino procedure or via a gastric conduit. This study compares postoperative complications and quality of life for both approaches. METHODS: All patients who underwent Merendino or gastric conduit reconstruction from 2011-2017 were included. Both groups were investigated regarding postoperative length of stay, complications, and gastrointestinal quality of life. RESULTS: 45 patients were identified, of which, 39 remained for analysis: 22 patients in the Merendino group and 17 patients in the gastric conduit group. The median age of patients in the gastric conduit group (71 (53-92) years) was significantly higher than in the Merendino group (58 (19-75) years), P = .0002. Hospital stay was significantly longer in the gastric conduit group (35.9 (11-82) days vs. 18.2 (7-43) days, P = .0299) and incidence of anastomotic leakage was higher (24% vs. 9%, P = .0171). General incidence of complications (Clavien-Dindo) did not vary (P = .1694). However, grade 5 complications only occurred in the Merendino group (n = 1). Evaluation of long-term outcome and quality of life showed dysphagia to only have occurred in the Merendino group (n = 3, 14%). DISCUSSION: Both approaches have advantages and disadvantages: The Merendino procedure showed reduced incidence of anastomotic leakage and shorter hospital stay but was associated with a higher in-hospital mortality rate. Discrepancies in subgroup populations as well as small patient numbers limit the interpretation of the findings. This study does however provide a first comparison of these surgical approaches and may serve as a basis for further investigation.

Microsurgical training course for clinicians and scientists: a 10-year experience at the Münster University Hospital.

BACKGROUND: Microsurgical techniques are an important part of clinical and experimental research. Here we present our step-by-step microsurgery training course developed at the Münster University Hospital. The goal of this course was to create a short, modular curriculum with clearly described and easy to follow working steps in accordance with the Guidelines for Training in Surgical Research in Animals by the Academy of Surgical Research. METHODS: Over the course of 10 years, we conducted an annual 2.5 day (20 h) microsurgical training course with a total of 120 participants. RESULTS: Prior to the course, 90% of the participants reported to have never performed a microanastomosis before. During the 10 years a total of 84.2% of the participants performed microanastomoses without assistance, 15% required assistance and only 0.8% failed. CONCLUSIONS: Our step-by-step microsurgery training course gives a brief overview of the didactic basics and the organization of a microsurgical training course and could serve as a guide for teaching microsurgical skills. During the 2.5-day curriculum, it was possible to teach, and for participants to subsequently perform a microsurgical anastomosis. The independent reproducibility of the learned material after the course is not yet known, therefore further investigations are necessary. With this step-by-step curriculum, we were able to conduct a successful training program, shown by the fact that each participant is able to perform microvascular anastomoses on a reproducible basis.

Management of Nonmalignant Tracheo- and Bronchoesophageal Fistula after Esophagectomy.

BACKGROUND: Tracheo- or bronchoesophageal fistula (TBF) occurring after esophagectomy represent a rare but devastating complication. Management remains challenging and controversial. Therefore, the purpose of this study was to evaluate the outcome of different treatment approaches and to propose recommendations for the management of TBF. METHODS: From 2008 to 2018, 15 patients were treated because of TBF and were analyzed with respect to fistula appearance, treatment strategy (stenting, endoscopic vacuum therapy and/or surgical reintervention) and outcome. RESULTS: In each case, the fistula was small, located close to the tracheal bifurcation and associated simultaneously (n = 6, 40%) or metachronously (n = 9, 60%) with an anastomotic leakage. Latter was covered by esophageal stents in six patients which in turn resulted in occurrence of TBF at a later time in five patients. Management of TBF included conservative therapy (n = 3), stenting (n = 6), or suturing (n = 6). Ten patients underwent rethoracotomy. Treatment failure was observed in eight patients (53%). In all patients, treatment was accompanied by progressive sepsis. On the contrary, all seven patients with successful defect closure remained in good general condition. CONCLUSION: Fistula appearance was similar in all patients. Implementation of esophageal stents cannot be recommended because of possibility of TBF at a later time point. Surgery is usually required and should preferably be performed when the patient's condition has been optimized at a single-stage repair. Esophageal diversion can only be recommended in patients with persisting mediastinitis. The key element for successful treatment of TBF, however, is control over sepsis; otherwise, outcome of TBF is devastating.

A novel histidine-tryptophan-ketoglutarate formulation ameliorates intestinal injury in a cold storage and ex vivo warm oxygenated reperfusion model in rats.

AIM: The present study aims to evaluate protective effects of a novel histidine-tryptophan-ketoglutarate solution (HTK-N) and to investigate positive impacts of an additional luminal preservation route in cold storage-induced injury on rat small bowels. METHODS: Male Lewis rats were utilized as donors of small bowel grafts. Vascular or vascular plus luminal preservation were conducted with HTK or HTK-N and grafts were stored at 4°C for 8 h followed by ex vivo warm oxygenated reperfusion with Krebs-Henseleit buffer for 30 min. Afterwards, intestinal tissue and portal vein effluent samples were collected for evaluation of morphological alterations, mucosal permeability and graft vitality. RESULTS: The novel HTK-N decreased ultrastructural alterations but otherwise presented limited effect on protecting small bowel from ischemia-reperfusion injury in vascular route. However, the additional luminal preservation led to positive impacts on the integrity of intestinal mucosa and vitality of goblet cells. In addition, vascular plus luminal preservation route with HTK significantly protected the intestinal tissue from edema. CONCLUSION: HTK-N protected the intestinal mucosal structure and graft vitality as a luminal preservation solution. Additional luminal preservation route in cold storage was shown to be promising.

Impact of nighttime procedures on outcomes after liver transplantation.

BACKGROUND: Sleep deprivation is a well-known risk factor for the performance of medical professionals. Solid organ transplantation (especially orthotopic liver transplantation (oLT)) appears to be vulnerable since it combines technically challenging operative procedures with an often unpredictable start time, frequently during the night. Aim of this study was to analyze whether night time oLT has an impact on one-year graft and patient survival. MATERIAL AND METHODS: Deceased donor oLTs between 2006 and 2017 were retrospectively analyzed and stratified for recipients with a start time at day (8 a.m. and 6 p.m.) or at night (6 p.m. to 8 a.m.). We examined donor as well as recipient demographics and primary outcome measure was one-year patient and graft survival. RESULTS: 350 oLTs were conducted in the study period, 154 (44%) during daytime and 196 (56%) during nighttime. Donor and recipient variables were comparable. One-year patient survival (daytime 75.3% vs nighttime 76.5%, p = 0.85) as well as graft survival (daytime 69.5% vs nighttime 73.5%, p = 0.46) were similar between the two groups. Frequencies of reoperation (daytime 53.2% vs nighttime 55.1%, p = 0.74) were also not significantly different. CONCLUSION: Our retrospective single center data derived from a German transplant center within the Eurotransplant region provides evidence that oLT is a safe procedure irrespective of the starting time. Our data demonstrate that compared to daytime surgery nighttime liver transplantation is not associated with a greater risk of surgical complications. In addition, one-year graft and patient survival do not display inferior results in patients undergoing nighttime transplantation.

The weekend effect in liver transplantation.

BACKGROUND: The weekend effect describes a phenomenon whereby patients admitted to hospitals on weekends are at higher risk of complications compared to those admitted during weekdays. However, if a weekend effect exists in orthotopic liver transplantation (oLT). METHODS: We analyzed oLT between 2006 and 2016 and stratified patients into weekday (Monday to Friday) and weekend (Saturday, Sunday) groups. Primary outcome measures were one-year patient and graft survival. RESULTS: 364 deceased donor livers were transplanted into 329 patients with 246 weekday (74.77%) and 83 weekend (25.23%) patients. Potential confounders (e.g. age, ischemia time, MELD score) were comparable. One-year patient and graft survival were similar. Frequencies of rejections, primary-non function or re-transplantation were not different. The day of transplantation was not associated with one-year patient and graft survival in multivariate analysis. CONCLUSIONS: We provide the first data for the Eurotransplant region on oLT stratified for weekend and weekday procedures and our findings suggest there was no weekend effect on oLT. While we hypothesize that the absent weekend effect is due to standardized transplant procedures and specialized multidisciplinary transplant teams, our results are encouraging showing oLT is a safe and successful procedure, independent from the day of the week.

Is there a "weekend effect" in kidney transplantation?

The 'weekend effect' describes increased adverse outcomes after weekend hospitalization. We examined weekend-weekday differences in the outcome of 580 patients following renal transplantation (RTx, brain dead donors) between January 2007 and December 2014 at our center. 3-year patient and graft survival, incidence of delayed graft function (DGF), acute rejections and estimated glomerular filtration rate (eGFR, CKD-EPI) at 1 year as well as surgical complications were assessed. Of all 580 transplants, 416 (71.7%) were performed on weekdays (Monday-Friday) and 164 (28.3%) on weekends (Saturday-Sunday). 3-year patient and graft survival, frequencies of DGF, acute rejections and 1-year eGFR as well as length of hospital stay were similar between RTx patients transplanted on weekdays or weekends, respectively. However, a noticeable difference was detected with regard to surgical complications which were more frequent in RTx patients transplanted on weekends. All results remained consistent across all definitions of weekend status. Our results suggest that weekend transplant status does not affect functional short-term and long-term outcomes after RTx. The standardized protocols and operationalized processes applied in RTx might contribute to this finding and may provide a model for other medical procedures that are performed on weekends to improve efficiency and outcomes. The higher rate of surgical complications after weekend RTx needs further elaboration to fully assess the presence of a weekend effect in RTx.

EPOR2/ßcR2-independendent effects of low-dose epoetin-α in porcine liver transplantation.

Ischemia-reperfusion injury (IRI) remains a key component of graft damage during transplantation. Erythropoietin (EPO) induces anti-inflammatory and anti-apoptotic effects via the EPOR2/ßcR2 complex, with a potential risk of thrombosis. Previous work indicates that EPO has EPOR2/ßcR2-independent protective effects via direct effects on the endothelium. As the EPOR2/ßcR2 receptor has a very low affinity for EPO, we aimed to test the hypothesis that EPO doses below the level that stimulate this receptor elicit cytoprotective effects via endothelial stimulation in a porcine liver transplantation model. Landrace pigs underwent allogenic liver transplantation (follow-up: 6 h) with a portojugular shunt. Animals were divided into two groups: donor and recipient treatment with low-dose EPO (65 IU/kg) or vehicle, administered 6 h before cold perfusion and 30 min after warm reperfusion. Fourteen of 17 animals (82.4%) fulfilled the inclusion criteria. No differences were noted in operative values between the groups including hemoglobin, cold or warm ischemic time. EPO-treated animals showed a significantly lower histopathology score, reduced apoptosis, oxidative stress, and most important a significant up-regulation of endothelial nitric oxide (NO) synthase (eNOS). Donor and recipient treatment with low-dose EPO reduces the hepatic IRI via EPOR2/ßcR2-independent cytoprotective mechanisms and represents a clinically applicable way to reduce IRI.

A practical guide for small bowel transplantation in rats-review of techniques and models.

BACKGROUND: Animal models are a central aspect in research on small bowel transplantation (SBTx). Among them, rats are the preferred species because of their widespread availability and cost effectiveness. Because the complexity of the surgical procedure could per se influence the outcome of an experiment, a standardized and comparable technique is important. Based on of the vast amount of different models and surgical techniques published to this point, a review seemed necessary to guide investigators when choosing the suitable model. MATERIALS AND METHODS: A systematic literature search of original articles published between 1965 and 2016 using the Medline Database regarding techniques of SBTx in rats was conducted according to the Preferred reporting Items for Systematic Reviews and Meta-Analyses guidelines. Articles describing a new technique or evaluating different techniques were considered. RESULTS: A total of 38 publications fulfilled the selection criteria and were included. Data from these publications were regarded as too heterogeneous for statistical analysis. Depending on graft length and placement, full-length and reduced length heterotopic and orthotopic models were differentiated. Important factors concerning a good survival rate are the chosen model (heterotopic has a better outcome compared with orthotopic), a vascular flush of the graft in situ, a careful luminal flush of the graft, adequate fluid resuscitation, and a warm ischemia time of less than 40 min. CONCLUSIONS: SBTx in rats remains a complex and challenging procedure, which necessitates a standardized technique as well as sufficient training. By choosing the optimal experimental model, applying established strategies, and proven techniques, a standardized and scientifically reliable model can be achieved.

Detection of different virus-specific CD8+ T cells after kidney transplantation.

BACKGROUND: The early diagnosis of viral reactivation after kidney transplantation (KTX) is an unsolved problem. Survey of virus-specific T-cell responses may identify patients at risk for viral reactivation. We therefore quantified virus-specific CD8+ T-cells to evaluate their potential predictive value for viral reactivation and infection in KTX patients. METHODS: We quantified the virus-specific responses of CD8+ T-cells for CMV, EBV, HPV and HHV in 23 patients undergoing KTX for 6 mo after transplantation. We enumerated T-cells for 36 virus-specific binding peptides and five different human leukocyte antigen (HLA) alleles through the binding of Class I iTAg major histocompatibility complex (MHC) tetramers. The patients' pre-operative serologic status for CMV and CMV-specific CD8+ T-cell numbers were correlated with one another (p=0.0046). RESULTS: Three patients had clinical CMV disease and all three remained or became CMV-tetramer-positive for at least one HLA allele during follow-up. Three of the four patients with viral infections caused by or reactivations of viruses other than CMV were initially negative for CMV-specific CD8+ T-cells but became CMV-positive. Most of the patients who were initially CMV-tetramer positive also had tetramer-positive T-cells specific for Epstein-Barr virus (EBV); human papillomavirus (HPV)-6b, -11, -16, or -18; or human herpesvirus (HHV)-8. All of the patients who developed viral disease other than that caused by CMV remained or became positive for at least one binding peptide that was specific for a virus not directly related to the clinical features of a viral disease. CONCLUSION: Patients who were positive for any virus had a significantly greater risk of developing complications of viral disease during the 6-mo follow-up period in the study (p=0.026), suggesting a general susceptibility to viral reactivation. The evaluation of virus-specific CD8+ T-cells may prospectively help to identify patients at risk for viral reactivation after KTX.

Role of angiotensin-1 receptor blockade in cirrhotic liver resection.

BACKGROUND: The regeneration capacity of cirrhotic livers might be affected by angiotensin-1 (AT1) receptors located on hepatic stellate cells (HSC). The effect of AT1 receptor blockade on microcirculation, fibrosis and liver regeneration was investigated. MATERIALS AND METHODS: In 112 Lewis rats, cirrhosis was induced by repetitive intraperitoneal injections of CCl(4) . Six hours, 3, 7 and 14 days after partial hepatectomy or sham operation, rats were sacrificed for analysis. Animals were treated with either vehicle or 5 mg/kg body weight losartan pre-operatively and once daily after surgery by gavage. Microcirculation and portal vein flow were investigated at 6 h. The degree of cirrhosis was assessed by Azan Heidenhein staining, activation of HSC by desmin staining, apoptosis by ssDNA detection and liver regeneration by Ki-67 staining. Changes in expression of various genes important for liver regeneration and fibrosis were analysed at 6 h and 3 days. Haemodynamic parameters and liver enzymes were monitored. RESULTS: Losartan treatment increased sinusoidal diameter, sinusoidal blood flow and portal vein flow after partial hepatectomy (P<0.05), but not after sham operation. AT1 receptor blockade resulted in increased apoptosis early after resection. HSC activation was reduced and after 7 days, a significantly lower degree of cirrhosis in resected animals was observed. Losartan increased the proliferation of hepatocytes at late time-points and of non-parenchymal cells early after partial hepatectomy (P<0.05). Tumour necrosis factor (TNF)-α was significantly upregulated at 6 h and stem cell growth factor (SCF) was downregulated at 3 days (P<0.05). CONCLUSION: Losartan increased hepatic blood flow, reduced HSC activation and liver fibrosis, but interfered with hepatocyte proliferation after partial hepatectomy in cirrhotic livers.

Perforating vein fistula is superior to forearm fistula in elderly haemodialysis patients with diabetes and arterial hypertension.

BACKGROUND: Access-related problems are one of the major causes of morbidity in elderly patients with chronic kidney disease. The aim of this study was to assess potential risks and benefits in elderly patients comparing forearm arteriovenous fistula (AVF) and perforating vein AVF below the elbow for primary vascular access. METHODS: A retrospective comparison of elderly patients (65.7 ± 9.3 years, 70.4% male patients, 36.2% late referral) undergoing primary vascular access surgery using forearm AVF (n = 50) and perforating vein AVF (n = 55) was performed over a 2-year period, including a multivariate analysis of potential risk factors and benefits of primary patency (PP = intervention-free access survival) and secondary patency (SP = access survival until abandonment). RESULTS: Patency rates after 24 months were significantly higher in patients with perforating vein AVF (PP + SP: 78.2%) compared to forearm AVF (PP: 62%, SP: 56%, P = 0.04). Presence of diabetes mellitus in patients with forearm AVF was associated with a decreased PP [odds ratio (OR): 3.6, 95% confidence interval (CI): 0.9-13.8] and SP (OR: 4.8, 95% CI: 1.3-17.9), and arterial hypertension was associated with a lower PP (OR: 6.7, 95% CI: 0.8-53.9), whereas the presence of hyperparathyroidism was associated with higher PP and SP (OR: 0.2, 95% CI: 0.1-0.7). In contrast, PP and SP in patients with perforating vein AVF were not influenced by comorbidities. CONCLUSIONS: Perforating vein AVF is superior to forearm AVF in elderly patients with diabetes and arterial hypertension due to the proximal fistula location, probably caused by an improved artery distensibility during fistula maturation.

Impact of failed allograft nephrectomy on initial function and graft survival after kidney retransplantation.

The management of an asymptomatic failed renal graft remains controversial. The aim of our study was to explore the effect of failed allograft nephrectomy on kidney retransplantation by comparing the outcome of recipients who underwent graft nephrectomy prior to retransplantation with those who did not. Retrospective comparison of patients undergoing kidney retransplantation with (group A, n = 121) and without (group B, n = 45) preliminary nephrectomy was performed, including subgroup analysis with reference to patients with multiple (≥2) retransplantations and patients of the European Senior Program (ESP). Nephrectomy leads to increased panel reactive antibody (PRA) levels prior to retransplantation and is associated with significantly increased rates of primary nonfunction (PNF; P = 0.05) and acute rejection (P = 0.04). Overall graft survival after retransplantation was significantly worse in group A compared with group B (P = 0.03). Among the subgroups especially ESP patients showed a shorter graft survival after previous allograft nephrectomy. On the multivariate analysis, pretransplant graft nephrectomy and PRA >70% were independent and significant risk factors associated with graft loss after kidney retransplantation. Nephrectomy of the failed allograft was not beneficial for retransplant outcome in our series. Patients with failed graft nephrectomy tended to have a higher risk of PNF and acute rejection after retransplantation. The possibility that the graft nephrectomy has a negative impact on graft function and survival after retransplantation is worth studying further.

Impact of rapamycin on liver regeneration.

The remarkable capacity of the liver to regenerate after injury and the prospects of organ self-renewal have attracted much interest in the understanding and modulation of the underlying molecular events. We investigated the effect of mammalian target of rapamycin (mTOR) inhibitor rapamycin (RAPA) on liver by correlating intravital microscopy, immunohistochemistry, and reverse transcriptase polymerase chain reaction in a rat model of 2/3 hepatectomy. RAPA significantly retarded proliferation of hepatocytes, endothelial cells, and hepatic stellate cells (HSCs) mostly between days 2 and 4 after hepatectomy and downregulated major cytokines and growth factors (tumor necrosis factor alpha, hepatocyte growth factor, platelet-derived growth factor, platelet-derived growth factor receptor, insulin-like growth factor-1, transforming growth factor beta 1) important for liver regeneration. These effects were almost absent at later time points. RAPA also had a transient, but broad effect on angiogenesis, and impaired sinusoidal density as well as mRNA levels of vascular endothelial growth factor, vascular endothelial growth factor receptor 1, vascular endothelial growth factor receptor 2, and angiopoietin-1. Activation of HSC was also transiently suppressed as observed by smooth muscle protein 1 alpha protein expression and intercellular adhesion molecule-1 mRNA levels. The rate of apoptosis in liver was significantly increased by RAPA between day 3 and day 7. The effect of RAPA on liver repair, angiogenesis, and HSC activation is confined to the phase of active cell proliferation. This transient effect might allow further exploration of mTOR inhibitors in clinical situations that involve liver regeneration, and seems to have implications beyond immunosuppression.