Prolonged culture of human pancreatic islets under glucotoxic conditions changes their acute beta cell calcium and insulin secretion glucose response curves from sigmoid to bell-shaped.

AIMS/HYPOTHESIS: The rapid remission of type 2 diabetes by a diet very low in energy correlates with a marked improvement in glucose-stimulated insulin secretion (GSIS), emphasising the role of beta cell dysfunction in the early stages of the disease. In search of novel mechanisms of beta cell dysfunction after long-term exposure to mild to severe glucotoxic conditions, we extensively characterised the alterations in insulin secretion and upstream coupling events in human islets cultured for 1-3 weeks at ~5, 8, 10 or 20 mmol/l glucose and subsequently stimulated by an acute stepwise increase in glucose concentration. METHODS: Human islets from 49 non-diabetic donors (ND-islets) and six type 2 diabetic donors (T2D-islets) were obtained from five isolation centres. After shipment, the islets were precultured for 3-7 days in RPMI medium containing ~5 mmol/l glucose and 10% (vol/vol) heat-inactivated FBS with selective islet picking at each medium renewal. Islets were then cultured for 1-3 weeks in RPMI containing ~5, 8, 10 or 20 mmol/l glucose before measurement of insulin secretion during culture, islet insulin and DNA content, beta cell apoptosis and cytosolic and mitochondrial glutathione redox state, and assessment of dynamic insulin secretion and upstream coupling events during acute stepwise stimulation with glucose [NAD(P)H autofluorescence, ATP/(ATP+ADP) ratio, electrical activity, cytosolic Ca2+ concentration ([Ca2+]c)]. RESULTS: Culture of ND-islets for 1-3 weeks at 8, 10 or 20 vs 5 mmol/l glucose did not significantly increase beta cell apoptosis or oxidative stress but decreased insulin content in a concentration-dependent manner and increased beta cell sensitivity to subsequent acute stimulation with glucose. Islet glucose responsiveness was higher after culture at 8 or 10 vs 5 mmol/l glucose and markedly reduced after culture at 20 vs 5 mmol/l glucose. In addition, the [Ca2+]c and insulin secretion responses to acute stepwise stimulation with glucose were no longer sigmoid but bell-shaped, with maximal stimulation at 5 or 10 mmol/l glucose and rapid sustained inhibition above that concentration. Such paradoxical inhibition was, however, no longer observed when islets were acutely depolarised by 30 mmol/l extracellular K+. The glucotoxic alterations of beta cell function were fully reversible after culture at 5 mmol/l glucose and were mimicked by pharmacological activation of glucokinase during culture at 5 mmol/l glucose. Similar results to those seen in ND-islets were obtained in T2D-islets, except that their rate of insulin secretion during culture at 8 and 20 mmol/l glucose was lower, their cytosolic glutathione oxidation increased after culture at 8 and 20 mmol/l glucose, and the alterations in GSIS and upstream coupling events were greater after culture at 8 mmol/l glucose. CONCLUSIONS/INTERPRETATION: Prolonged culture of human islets under moderate to severe glucotoxic conditions markedly increased their glucose sensitivity and revealed a bell-shaped acute glucose response curve for changes in [Ca2+]c and insulin secretion, with maximal stimulation at 5 or 10 mmol/l glucose and rapid inhibition above that concentration. This novel glucotoxic alteration may contribute to beta cell dysfunction in type 2 diabetes independently from a detectable increase in beta cell apoptosis.

First clinical kidney transplantation series using brief bubble and direct surface oxygenation as alternative for membrane oxygenation during hypothermic machine perfusion.

BACKGROUND: Active oxygen during hypothermic machine perfusion has the potential to improve mitochondrial preservation and subsequently decrease the harmful effects of ischemia reperfusion injury. Brief bubble, and subsequent surface oxygenation are an alternative oxygenation technique for membrane-oxygenated kidneys during hypothermic machine perfusion (HMP). METHODS: Between March 20, 2022, and June 13, 2022, 5 kidney grafts originating from 3 donors after circulatory death were oxygenated by bubble and surface oxygenation during HMP. RESULTS: No adverse events related to this new oxygenation technique were observed. All five recipients experienced no dialysis-dependency after transplantation with excellent initial graft function at 3 months after transplantation. CONCLUSIONS: For the first time in human, this new oxygenation technique was successfully applied to 5 HMP-kidneys, originating from donation after circulatory death. If confirmed on larger scale cohorts, this innovative oxygenation technique, as alternative oxygenation technique for membrane-oxygenated kidneys, has the potential to be widely implemented because its simplicity and efficacy, and reducing economic and ecological costs by eliminating the need for a membrane oxygenator and oxygen source during transport.

miR-199a Downregulation as a Driver of the NOX4/HIF-1α/VEGF-A Pathway in Thyroid and Orbital Adipose Tissues from Graves' Patients.

Graves' disease (GD) is an autoimmune thyroiditis often associated with Graves' orbitopathy (GO). GD thyroid and GO orbital fat share high oxidative stress (OS) and hypervascularization. We investigated the metabolic pathways leading to OS and angiogenesis, aiming to further decipher the link between local and systemic GD manifestations. Plasma and thyroid samples were obtained from patients operated on for multinodular goiters (controls) or GD. Orbital fats were from GO or control patients. The NADPH-oxidase-4 (NOX4)/HIF-1α/VEGF-A signaling pathway was investigated by Western blotting and immunostaining. miR-199a family expression was evaluated following quantitative real-time PCR and/or in situ hybridization. In GD thyroids and GO orbital fats, NOX4 was upregulated and correlated with HIF-1α stabilization and VEGF-A overexpression. The biotin assay identified NOX4, HIF-1α and VEGF-A as direct targets of miR-199a-5p in cultured thyrocytes. Interestingly, GD thyroids, GD plasmas and GO orbital fats showed a downregulation of miR-199a-3p/-5p. Our results also highlighted an activation of STAT-3 signaling in GD thyroids and GO orbital fats, a transcription factor known to negatively regulate miR-199a expression. We identified NOX4/HIF-1α/VEGF-A as critical actors in GD and GO. STAT-3-dependent regulation of miR-199a is proposed as a common driver leading to these events in GD thyroids and GO orbital fats.

Erythropoiesis and chronic kidney disease-related anemia: From physiology to new therapeutic advancements.

Erythropoiesis is triggered by hypoxia and is strictly regulated by hormones, growth factors, cytokines, and vitamins to ensure an adequate oxygen delivery to all body cells. Abnormalities in one or more of these factors may induce different kinds of anemia requiring different treatments. A key player in red blood cell production is erythropoietin. It is a glycoprotein hormone, mainly produced by the kidneys, that promotes erythroid progenitor cell survival and differentiation in the bone marrow and regulates iron metabolism. A deficit in erythropoietin synthesis is the main cause of the normochromic normocytic anemia frequently observed in patients with progressive chronic kidney disease. The present review summarizes the most recent findings about each step of the erythropoietic process, going from the renal oxygen sensing system to the cascade of events induced by erythropoietin through its own receptor in the bone marrow. The paper also describes the new class of drugs designed to stabilize the hypoxia-inducible factor by inhibiting prolyl hydroxylase, with a discussion about their metabolism, disposition, efficacy, and safety. According to many trials, these drugs seem able to simulate tissue hypoxia and then stimulate erythropoiesis in patients affected by renal impairment. In conclusion, the in-depth investigation of all events involved in erythropoiesis is crucial to understand anemia pathophysiology and to identify new therapeutic strategies, in an attempt to overcome the potential side effects of the commonly used erythropoiesis-stimulating agents.

The effect on early renal function of various dynamic preservation strategies in a preclinical pig ischemia-reperfusion autotransplant model.

The aims of this study were to determine the most optimal timing to start machine perfusion during kidney preservation to improve early graft function and to evaluate the impact of temperature and oxygen supply during machine perfusion in a porcine ischemia-reperfusion autotransplant model. The left kidney of an approximately 40-kg female Belgian Landrace pig was exposed to 30 minutes of warm ischemia via vascular clamping and randomized to 1 of 6 study groups: (1) 22-hour static cold storage (SCS) (n = 6), (2) 22-hour hypothermic machine perfusion (HMP) (n = 6), (3) 22-hour oxygenated HMP (n = 7), (4) 20-hour HMP plus 2-hour normothermic perfusion (NP) (n = 6), (5) 20-hour SCS plus 2-hour oxygenated HMP (n = 7), and (6) 20-hour SCS plus 2-hour NP (n = 6). Graft recovery measured by serum creatinine level was significantly faster for continuous HMP preservation strategies compared with SCS alone and for all end-ischemic strategies. The active oxygenated 22-hour HMP group demonstrated a significantly faster recovery from early graft function compared with the 22-hour nonactive oxygenated HMP group. Active oxygenation was also found to be an important modulator of a faster increase in renal flow during HMP preservation. Continuous oxygenated HMP applied from the time of kidney procurement until transplant might be the best preservation strategy to improve early graft function.

Preperitoneal Surgical Approach to Treat Vesicoureteral Anastomotic Leakage, Distal Stenosis or Reflux After Kidney Transplantation.

BACKGROUND: If endourological approaches are not applicable to treat vesicoureteral anastomotic complications after kidney transplantation, the surgical gold standard in many transplant centers is pyeloureterostomy or ureteroureterostomy using the native ureter. We report an original preperitoneal technique that can be used for vesicoureteral reanastomosis in kidney transplant recipients not eligible for endourological treatment. METHODS: Between January 2011 and December 2015, 18 kidney transplant recipients underwent this new surgical procedure. Of this number, 15 subjects with at least 1 year of follow-up were included in the analysis. The indications were vesicoureteral reflux, anastomotic stenosis, and leakage in 8, 5, and 2 patients, respectively. Briefly, a double J stent was preoperatively inserted into the grafted ureter. Surgery was performed through a Pfannenstiel incision. The preperitoneal space surrounding the bladder was dissected and the distal part of the grafted ureter was identified and mobilized. The anastomotic area was resected and another vesicoureteral anastomosis was performed (Lich-Gregoir technique), keeping the JJ stent in place for three weeks. RESULTS: This procedure was performed 213 days (range 17-2608) after kidney transplantation. Median surgical duration was 179 minutes (range 112-314) and median hospital stay 8 days (range 4-14). The success rate was 86.7% (13/15), with a median follow-up of 1148 days (range 517-1808). In two patients, symptomatic recurrence of vesicoureteral reflux required a pyeloureterostomy using the native ureter. CONCLUSIONS: The authors describe a simple technique that avoids transperitoneal dissection, potentially yielding more esthetic results thanks to easy access, as well as excellent outcomes.

Opposite actions of urotensin II and relaxin-2 on cellular expression of fibronectin in renal fibrosis: A preliminary experimental study.

Our aim was to evaluate the role of urotensin II, urantide (urotensin II receptor antagonist) and relaxin-2 on the cellular expression of fibronectin as a surrogate marker for renal fibrosis. We employed LLC-PK1 renal tubular epithelial cells and assessed the influence on the fibrotic process of the above-mentioned substances by using anti-fibronectin antibodies in western blot analysis. The addition of urotensin II increased fibronectin expression. Urantide reduced the positivity for fibronectin caused by urotensin II (P<.05). The anti-fibrotic action was more evident for relaxin-2 (P<.01). Also in the model of TGF-ß1-induced fibrosis, urantide and, to a greater extent, relaxin-2 were able to significantly lessen fibronectin expression (respectively, P<.05 and P<.01). In conclusion, relaxin-2 may reduce urotensin II-induced renal fibrosis.

Unusual presentations of enlarged parathyroid cysts: two case reports.

INTRODUCTION: Parathyroid cysts are infrequently encountered and have a variable presentation pattern depending on their size, location and secreting character. PATIENTS AND METHODS: We report two cases of parathyroid cysts characterized by their uncommon clinical presentation. RESULTS: In the first case the patient presented with a large cervical cystic mass without hypercalcemia, while in the second case, the patient experienced a hypercalcemic crisis associated with acute renal failure. The variable pattern of clinical manifestations is discussed. CONCLUSION: Parathyroid cysts are a rare entity. Surgical resection is the key to therapy when hyperparathyroidism or local compression are identified.

Delayed graft function and chronic allograft nephropathy: diagnostic and prognostic role of neutrophil gelatinase-associated lipocalin.

CONTEXT: Available markers are not reliable parameters to early detect kidney injury in transplanted patients. OBJECTIVE: Examine neutrophil gelatinase associated lipocalin (NGAL) in early detection of delayed graft function (DGF) and as a long-term predictor of graft outcome. PATIENTS AND METHODS: NGAL was evaluated in 124 transplanted patients. RESULTS: Urinary NGAL levels were associated to a 10% (HR: 1.10; 95% CI: 1.04-1.25; p < 0.001) and 15% (HR: 1.15; 95% CI: 1.09-1.26; p < 0.001) increased risk of DGF and allograft nephropathy progression, respectively. CONCLUSION: NGAL reflects the entity of renal impairment in transplanted patients, representing a biomarker and an independent risk factor for DGF and chronic allograft nephropathy progression.

Semaphorin 3A serum levels are influenced by haemodialysis: what clinical significance?

AIM: Semaphorin 3A urinary levels represent an early, predictive biomarker of acute kidney injury and positively correlate with albumin-to-creatinine ratio and serum creatinine in hypertensive patients with chronic kidney disease. Our purpose has been to evaluate semaphorin 3A serum levels in a cohort of haemodialysis (HD) patients, the influence of a single HD session on its concentrations, and the potential correlation with clinical and biochemical parameters. METHODS: We enrolled 18 patients receiving HD with Acetate-Free Biofiltration technique and 16 healthy subjects as controls. Peripheral venous blood samples were obtained from patients at different intervals: start of dialysis (pre-HD), middle, and end of the treatment (post-HD). We also collected dialysate samples by the Quantiscan monitoring system (Hospal, Bologna, Italy). RESULTS: Semaphorin 3A was significantly lower in HD patients at baseline compared to controls (median 19.50 (interquartile range 1.00-65.00) versus 97.50 (23.50-161.00) ng/mL, P = 0.0237). A statistically significant reduction was seen during a single HD session (from 19.50 (1.00-65.00) to 0.86 (0.82-4.21) ng/mL, P < 0.0001), with a reduction ratio of 65.92 ± 33.51%. The median concentration in dialysate was 54.00 (15.00-102.00) ng/mL. Pre-HD values were directly related to serum vitamin D (r = 0.872; P = 0.001) and inversely correlated with calcium levels (r = -0.426; P = 0.012) and calcium × phosphate product (r = -0.422; P = 0.0252). CONCLUSION: Semaphorin 3A removal during HD may be clinically relevant due to its involvement in different aspects of cell physiology and in bone remodelling. Semaphorin 3A both inhibits osteoclastic bone reabsorption and increases osteoblastic new bone formation, thus playing a dual osteoprotective role.

Nephro-oncology: a link in evolution.

A multidisciplinary approach represents the best method to interact with patients. Neoplastic and renal diseases are closely related to each other because of an increased risk of cancer among individuals with end-stage renal disease and because of the high prevalence of renal failure in cancer patients. Physicians should be able to know how to prevent and treat the possible complications which may appear during the course of neoplastic disease that may lead to kidney damage such as the Acute Tumor Lysis Syndrome, disorders of hydroelectrolitic balance, metabolic alterations in the calcium-phosphorus, anemia, interstitial and glomerular impairment due to chemotherapy. It is very important to know patients' renal function and directly monitor it, before and during treatment, using formulas for estimating glomerular filtration rate (GFR) and above all, specific biomarkers are more early and sensitive than the increase of creatinine, like neutrophil gelatinase-associated lipocalin. Additionally, physician should consider that alteration of GFR or substitutive renal treatments severely influence dosage of tumor markers and it could lead to wrong diagnosis of cancer. The aim of this article is to provide a review of problems related to cancer relevant in the development of renal failure and try to define the best therapeutic strategies to cope with possible kidney imbalances induced by cancer or its treatment.

Auxin induces cell proliferation in an experimental model of mammalian renal tubular epithelial cells.

Indole-3-acetic acid is the main auxin produced by plants and plays a key role in the plant growth and development. This hormone is also present in humans where it is considered as a uremic toxin deriving from tryptophan metabolism. However, beyond this peculiar aspect, the involvement of auxin in human pathophysiology has not been further investigated. Since it is a growth hormone, we evaluated its proliferative properties in an in vitro model of mammalian renal tubular epithelial cells. We employed an experimental model of renal tubular epithelial cells belonging to the LLC-PK1 cell line that is derived from the kidney of healthy male pig. Growth effects of auxin against LLC-PK1 cell lines were determined by a rapid colorimetric assay. Increasing concentrations of auxin (to give a final concentration from 1 to 1000 ng/mL) were added and microplates were incubated for 72 h. Each auxin concentration was assayed in four wells and repeated four times. Cell proliferation significantly increased, compared to control cells, 72 h after addition of auxin to cultured LLC-PK1 cells. Statistically significant values were observed when 100 ng/mL (p < 0.01) and 1000 ng/mL (p < 0.05) were used. In conclusion, auxin influences cell growth not only in plants, where its role is well documented, but also in mammalian cell lines. This observation opens new scenarios in the field of tissue regeneration and may stimulate a novel line of research aiming at investigating whether this hormone really influences human physiology and pathophysiology and in particular, kidney regeneration.

Relaxin: new pathophysiological aspects and pharmacological perspectives for an old protein.

Human relaxin-2 (hereafter simply defined as "relaxin") is a 6-kDa peptidic hormone best known for the physiological role played during pregnancy in the growth and differentiation of the reproductive tract and in the renal and systemic hemodynamic changes. This factor can also be involved in the pathophysiology of arterial hypertension and heart failure, in the molecular pathways of fibrosis and cancer, and in angiogenesis and bone remodeling. It belongs to the relaxin peptide family, whose members comprehensively exert numerous effects through interaction with different types of receptors, classified as relaxin family peptide (RXFP) receptors (RXFP1, RXFP2, RXFP3, RXFP4). Research looks toward the in-depth examination and complete understanding of relaxin in its various pleiotropic actions. The intent is to evaluate the likelihood of employing this substance for therapeutic purposes, for instance in diseases where a deficit could be part of the underlying pathophysiological mechanisms, also avoiding any adverse effect. Relaxin is already being considered as a promising drug, especially in acute heart failure. A careful study of the different RXFPs and their receptors and the comprehension of all biological activities of these hormones will probably provide new drugs with a potential wide range of therapeutic applications in the near future.

Menstrual and reproductive factors in the risk of differentiated thyroid carcinoma in young women in France: a population-based case-control study.

The incidence of thyroid cancer has increased in eastern Europe since the Chernobyl nuclear power plant accident. Although the radioactive fallout was much less severe and the thyroid radiation dose was much lower in France, a case-control study was initiated in eastern France. The present study included 633 young women who were diagnosed with differentiated thyroid cancer before 35 years of age between 2002 and 2006 and matched with 677 controls. Face-to-face interviews were conducted from 2005 to 2010. Odds ratios were calculated using conditional logistic regressions and were reported in the total group and by histopathological type of cancer ("only papillary" and "excluding microcarcinomas"). The risk of thyroid cancer was higher in women who had a higher number of pregnancies, used a lactation suppressant, or had early menarche. Conversely, breastfeeding, oral contraceptive use, and late age at first pregnancy were associated with a lower risk of thyroid cancer. No association was observed between thyroid cancer and having irregular menstrual cycle, undergoing treatment for menstrual cycle regularity shortly after menarche, having a cessation of menstruation, use of another contraceptive, history of miscarriage or abortion for the first pregnancy, or having had gestational diabetes. This study confirms the role of hormonal and reproductive factors in thyroid cancer, and our results support the fact that exposure to estrogens increases thyroid cancer risk.

From water to aquaretics: a legendary route.

Man is water. When life appeared on earth, the primordial cell had a simple structure and could immediately ascertain from the surrounding aquatic environment the substances for nutrition and oxygen, without any need for structural complexity. As part of evolution, during the transition from aquatic to terrestrial life, vertebrates had to fight against dehydration as well as fish in the sea. In this complex mechanism of osmoregulation, the structure and function of some osmoregulatory hormones have been maintained during the evolution of species, from fish to man. Within the homeostatic mechanism, the renin-angiotensin-aldosterone system (RAAS) is crucial in the regulation of renal reasorption of water and sodium. It is also involved in the regulation of renal plasma flux, blood volume and blood pressure. Vasopressin plays a hormonal function in the mechanisms of water homeostasis acting through Aquaporins (AQP), channel-proteins that allow bi-directional water transport across cell membranes.

Donor- and isolation-related predictive factors of in vitro secretory function of cultured human islets.

Background and aims: Human islet preparations designated for research exhibit diverse insulin-secretory profiles. This study aims to assess the impact of donor- and isolation-related factors on in vitro islet secretory function. Methods: A retrospective analysis of 46 isolations from 23 pancreata discarded for clinical transplantation was conducted. In vitro islet secretory function tests were performed on Day 1 and Day 7 of culture. Linear mixed-effects models (LMMs) were employed to investigate the relationships between various predictors characterizing the patient and donor characteristics as well as the isolation effectiveness and two functional outcomes including the islet stimulation index (SI) and area under the insulin curve (AUC). Fixed effects were introduced to represent the main effects of each predictor, and backward elimination was utilized to select the most significant fixed effects for the final model. Interaction effects between the timepoint (Day 7 vs. Day 1) and the predictors were also evaluated to assess whether predictors were associated with the temporal evolution of SI and AUC. Fold-change (Fc) values associated with each predictor were obtained by exponentiating the corresponding coefficients of the models, which were built on log-transformed outcomes. Results: Analysis using LMMs revealed that donor body mass index (BMI) (Fc = 0.961, 95% CI = 0.927-0.996, p = 0.05), donor gender (female vs. male, Fc = 0.702, 95% CI = 0.524-0.942, p = 0.04), and donor hypertension (Fc = 0.623, 95% CI = 0.466-0.832, p= <0.01) were significantly and independently associated with SI. Moreover, donor gender (Fc = 0.512, 95% CI = 0.302-0.864, p = 0.02), donor cause of death (cerebrovascular accident vs. cardiac arrest, Fc = 2.129, 95% CI = 0.915-4.946, p = 0.09; trauma vs. cardiac arrest, Fc = 2.129, 95% CI = 1.112-7.106, p = 0.04), pancreas weight (Fc = 1.01, 95% CI = 1.001-1.019, p = 0.03), and islet equivalent (IEQ)/mg (Fc = 1.277, 95% CI = 1.088-1.510, p ≤ 0.01) were significantly and independently associated with AUC. There was no predictor significantly associated with the temporal evolution between Day 1 and Day 7 for both SI and AUC outcomes. Conclusion: This study identified donor- and isolation-related factors influencing in vitro islet secretory function. Further investigations are essential to validate the applicability of these results in clinical practice.

Exploring Preservation Modalities in a Split Human Pancreas Model to Investigate the Effect on the Islet Isolation Outcomes.

Background: In islet transplantation, the use of dynamic hypothermic preservation techniques is a current challenge. This study compares the efficacy of 3 pancreas preservation methods: static cold storage, hypothermic machine perfusion (HMP), and oxygenated HMP. Methods: A standardized human pancreas split model was employed using discarded organs from both donation after brain death (n = 15) and donation after circulatory death (DCD) (n = 9) donors. The pancreas head was preserved using static cold storage (control group), whereas the tail was preserved using the 3 different methods (study group). Data on donor characteristics, pancreas histology, isolation outcomes, and functional tests of isolated islets were collected. Results: Insulin secretory function evaluated by calculating stimulation indices and total amount of secreted insulin during high glucose stimulation (area under the curve) through dynamic perifusion experiments was similar across all paired groups from both DCD and donation after brain death donors. In our hands, islet yield (IEQ/g) from the pancreas tails used as study groups was higher than that of the pancreas heads as expected although this difference did not always reach statistical significance because of great variability probably due to suboptimal quality of organs released for research purposes. Moreover, islets from DCD organs had greater purity than controls (P ≤ 0.01) in the HMP study group. Furthermore, our investigation revealed no significant differences in pancreas histology, oxidative stress markers, and apoptosis indicators. Conclusions: For the first time, a comparative analysis was conducted, using a split model, to assess the effects of various preservation methods on islets derived from pancreas donors. Nevertheless, no discernible variances were observed in terms of islet functionality, histological attributes, or isolation efficacy. Further investigations are needed to validate these findings for clinical application.

Renal allograft implantation on prosthetic vascular grafts: short- and long-term results.

BACKGROUND: Arterial anastomosis in transplant patients with severe aortic and iliac atheromatosis is technically challenging and may jeopardize the success of the transplantation procedure. The aim of this retrospective study was to report short- and long-term results of a consecutive series of kidney transplant patients in whom the renal artery was implanted on a prosthetic vascular graft. MATERIALS AND METHODS: Medical charts and outpatient clinical records of patients who had undergone renal artery implantation on a prosthetic graft were reviewed. Data on patient characteristics, indications for transplantation, prior vascular procedures, surgical technique, and postoperative and long-term outcome were collected. RESULTS: The renal artery was implanted on a prosthetic graft in the course of 27 kidney transplantation procedures. Patients were divided into three groups according to the timing of the vascular intervention in relation to the transplantation. In group A (n = 22), the vascular prosthesis was implanted before kidney transplantation, in group B (n = 2), prosthetic iliac artery replacement and kidney transplantation were performed simultaneously, while in group C (n = 3), the vascular prosthesis was implanted after kidney transplantation. After a median follow-up of 50.5 months, one case of early arterial thrombosis was observed (3.7 %). Infectious complications occurred in two patients (7.4 %) related to mycotic pseudoaneurysms. One hematoma and one evisceration were also encountered, but no late arterial thrombosis nor stenosis were noted. Mean creatinine levels at 1 and 5 years of follow-up were 1.32 ± 0.36 and 1.27 ± 0.56 mg/dl, respectively. Five-year patient and graft survival rates were 85.2 and 74 %, respectively. CONCLUSIONS: Grafting of the renal artery to a vascular prosthesis is feasible and yields good results, despite the technical difficulties involved. We stress the importance of good teamwork.

Continuous vs. discontinuous purification of isolated human islets: functional and morphological comparison.

Background: The COBE 2991 cell processor, commonly used for pancreatic islet isolation, is no longer distributed in Europe, leading to a search for alternative purification procedures with equivalent efficacy. The aim of this study was to evaluate the efficacy of an alternative method based on the discontinuous purification of islets. Methods: The conventional isolation procedure using a standard continuous islet purification with COBE 2991 of n = 4 human pancreas was compared to n = 8 procedures using a discontinuous purification with a "bottle" method from donors of similar characteristics. Islet equivalents, purity, and dynamic glucose-stimulated insulin secretion were evaluated. Results: A similar islet yield was obtained using continuous vs. discontinuous purification methods (76,292.5 ± 40,550.44 vs. 79,625 ± 41,484.46 islet equivalents, p = 0.89). Islets from both groups had similar purity (78.75% ± 19.73% vs. 55% ± 18.16%, p = 0.08) and functionality both in terms of stimulation index (3.31 ± 0.83 vs. 5.58 ± 3.38, p = 0.22) and insulin secretion (1.26 ± 0.83 vs. 1.53 ± 1.40 mean AUC, p = 0.73). Moreover, the size of the islets was significantly larger in the discontinuous vs. continuous purification group (19.2% ± 10.3% vs. 45.4% ± 18.8% of islets less than 100 µm, p = 0.0097 and 23.7% ± 5.3% vs. 15.6% ± 5.8% of 200-250 µm islet size, p = 0.03). Conclusion: Compared to the conventional purification procedure, discontinuous purification with a bottle method shows similar results with regard to isolation yield and islet secretory function. Furthermore, this alternative technique allows for obtaining larger islets.