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12 result(s) for "van Leeuwen, Otto B"
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Bile proteome reveals biliary regeneration during normothermic preservation of human donor livers
Normothermic machine perfusion (NMP) after static cold storage is increasingly used for preservation and assessment of human donor livers prior to transplantation. Biliary viability assessment during NMP reduces the risk of post-transplant biliary complications. However, understanding of molecular changes in the biliary system during NMP remains incomplete. We performed an in-depth, unbiased proteomics analysis of bile collected during sequential hypothermic machine perfusion, rewarming and NMP of 55 human donor livers. Longitudinal analysis during NMP reveals proteins reflective of cellular damage at early stages, followed by upregulation of secretory and immune response processes. Livers with bile chemistry acceptable for transplantation reveal protein patterns implicated in regenerative processes, including cellular proliferation, compared to livers with inadequate bile chemistry. These findings are reinforced by detection of regenerative gene transcripts in liver tissue before machine perfusion. Our comprehensive bile proteomics and liver transcriptomics data sets provide the potential to further evaluate molecular mechanisms during NMP and refine viability assessment criteria. Normothermic machine perfusion (NMP) is increasingly used for preserving and evaluating donor livers before transplantation. Here, the authors demonstrate increased regenerative protein profiles in the bile of perfused livers considered suitable for transplantation, providing insight into the mechanisms linked to recovery of the biliary tree following ischemia-reperfusion injury.
Transplantation of high-risk donor livers after resuscitation and viability assessment using a combined protocol of oxygenated hypothermic, rewarming and normothermic machine perfusion: study protocol for a prospective, single-arm study (DHOPE-COR-NMP trial)
IntroductionExtended criteria donor (ECD) livers are increasingly accepted for transplantation in an attempt to reduce the gap between the number of patients on the waiting list and the available number of donor livers. ECD livers; however, carry an increased risk of developing primary non-function (PNF), early allograft dysfunction (EAD) or post-transplant cholangiopathy. Ischaemia-reperfusion injury (IRI) plays an important role in the development of these complications. Machine perfusion reduces IRI and allows for reconditioning and subsequent evaluation of liver grafts. Single or dual hypothermic oxygenated machine perfusion (DHOPE) (4°C–12°C) decreases IRI by resuscitation of mitochondria. Controlled oxygenated rewarming (COR) may further reduce IRI by preventing sudden temperature shifts. Subsequent normothermic machine perfusion (NMP) (37°C) allows for ex situ viability assessment to facilitate the selection of ECD livers with a low risk of PNF, EAD or post-transplant cholangiopathy.Methods and analysisThis prospective, single-arm study is designed to resuscitate and evaluate initially nationwide declined ECD livers. End-ischaemic DHOPE will be performed for the initial mitochondrial and graft resuscitation, followed by COR of the donor liver to a normothermic temperature. Subsequently, NMP will be continued to assess viability of the liver. Transplantation into eligible recipients will proceed if all predetermined viability criteria are met within the first 150 min of NMP. To facilitate machine perfusion at different temperatures, a perfusion solution containing a haemoglobin-based oxygen carrier will be used. With this protocol, we aim to transplant extra livers. The primary endpoint is graft survival at 3 months after transplantation.Ethics and disseminationThis protocol was approved by the medical ethical committee of Groningen, METc2016.281 in August 2016 and registered in the Dutch Trial registration numberTrial registration numberNTR5972, NCT02584283.
Hypothermic Machine Perfusion in Liver Transplantation — A Randomized Trial
In a multicenter, controlled trial, patients undergoing transplantation of a liver from a donor after circulatory death were randomly assigned to receive the liver after hypothermic oxygenated machine perfusion or conventional static cold storage. Hypothermic perfusion led to a lower risk of post-transplantation nonanastomotic biliary strictures.
The First Case of Ischemia-Free Kidney Transplantation in Humans
Ischemia-reperfusion injury (IRI) has been considered an inevitable event in organ transplantation since the first successful kidney transplant was performed in 1954. To avoid IRI, we have established a novel procedure called ischemia-free organ transplantation. Here, we describe the first case of ischemia-free kidney transplantation (IFKT). The kidney graft was donated by a 19-year-old brain-dead donor. The recipient was a 47-year-old man with end-stage diabetic nephropathy. The graft was procured, preserved, and implanted without cessation of blood supply using normothermic machine perfusion. The graft appearance, perfusion flow, and urine production suggested that the kidney was functioning well-during the whole procedure. The creatinine dropped rapidly to normal range within 3 days post-transplantation. The levels of serum renal injury markers were low post-transplantation. No rejection or vascular or infectious complications occurred. The patient had an uneventful recovery. This paper marks the first case of IFKT in humans. This innovation may offer a unique solution to optimizing transplant outcomes in kidney transplantation.
Oxygen Transport during Ex Situ Machine Perfusion of Donor Livers Using Red Blood Cells or Artificial Oxygen Carriers
Oxygenated ex situ machine perfusion of donor livers is an alternative for static cold preservation that can be performed at temperatures from 0 °C to 37 °C. Organ metabolism depends on oxygen to produce adenosine triphosphate and temperatures below 37 °C reduce the metabolic rate and oxygen requirements. The transport and delivery of oxygen in machine perfusion are key determinants in preserving organ viability and cellular function. Oxygen delivery is more challenging than carbon dioxide removal, and oxygenation of the perfusion fluid is temperature dependent. The maximal oxygen content of water-based solutions is inversely related to the temperature, while cellular oxygen demand correlates positively with temperature. Machine perfusion above 20 °C will therefore require an oxygen carrier to enable sufficient oxygen delivery to the liver. Human red blood cells are the most physiological oxygen carriers. Alternative artificial oxygen transporters are hemoglobin-based oxygen carriers, perfluorocarbons, and an extracellular oxygen carrier derived from a marine invertebrate. We describe the principles of oxygen transport, delivery, and consumption in machine perfusion for donor livers using different oxygen carrier-based perfusion solutions and we discuss the properties, advantages, and disadvantages of these carriers and their use.
Prolonged dual hypothermic oxygenated machine preservation (DHOPE-PRO) in liver transplantation: study protocol for a stage 2, prospective, dual-arm, safety and feasibility clinical trial
IntroductionEnd-ischaemic preservation of a donor liver by dual hypothermic oxygenated machine perfusion (DHOPE) for 2 hours prior to transplantation is sufficient to mitigate ischaemia-reperfusion damage and fully restore cellular energy levels. Clinical studies have shown beneficial outcomes after transplantation of liver grafts preserved by DHOPE compared with static cold storage. In addition to graft reconditioning, DHOPE may also be used to prolong preservation time, which could facilitate logistics for allocation and transplantation globally.Methods and analysisThis is a prospective, pseudo-randomised, dual-arm, IDEAL-D (Idea, Development, Exploration, Assessment, Long term study-Framework for Devices) stage 2 clinical device trial designed to determine safety and feasibility of prolonged DHOPE (DHOPE-PRO). The end-time of the donor hepatectomy will determine whether the graft will be assigned to the intervention (16:00–3:59 hour) or to the control arm (4:00–15:59 hour). In total, 36 livers will be included in the study. Livers in the intervention group (n=18) will undergo DHOPE-PRO (≥4 hours) until implantation the following morning, whereas livers in the control group (n=18) will undergo regular DHOPE (2 hours) prior to implantation. The primary endpoint of this study is a composite of the occurrence of all (serious) adverse events during DHOPE and up to 30 days after liver transplantation.Ethics and disseminationThe protocol was approved by the Medical Ethical Committee of Groningen, METc2020.126 in June 2020, and the study was registered in the Netherlands National Trial Registry (https://www.trialregister.nl/) prior to initiation.Trial registration numberNL8740.
Prospective diagnostic accuracy study of history taking and physical examination for adults with vertigo in general practice: study protocol
IntroductionVertigo is a prevalent and burdensome symptom. More than 80% of patients with vertigo are primarily treated by their general practitioner (GP) and are never referred to a medical specialist. Despite this therapeutic responsibility, the GP’s diagnostic toolkit has serious limitations. All recommended tests lack empirical evidence, because a diagnostic accuracy study on vestibular disorders (‘How well does test x discriminate between patients with or without target condition y?’) has never been performed in general practice. The VERtigo DIagnosis study aims to fill this gap.Methods and analysisWe will perform a diagnostic accuracy study on vertigo of primary vestibular origin in general practice to assess the discriminative ability of history taking and physical examination. We will compare all index tests with a respective reference standard. We will focus on five target conditions that account for more than 95% of vertigo diagnoses in general practice: (1) benign paroxysmal positional vertigo, (2) vestibular neuritis, (3) Ménière’s disease, (4) vestibular migraine (VM) and (5) central causes other than VM. As these five target conditions have a different pathophysiology and lack one generally accepted gold standard, we will use consensus diagnosis as a construct reference standard. Data for each patient, including history, physical examination and additional tests as recommended by experts in an international Delphi procedure, will be recorded on a standardised form and independently reviewed by a neurologist and otorhinolaryngologist. For each patient, the reviewers have to decide about the presence/absence of each target condition. We will calculate sensitivity, specificity, predictive values, likelihood ratios and diagnostic ORs, followed by decision rules for each target condition.Ethics and disseminationThe study obtained approval from the Vrije Universiteit Medical Center Medical Ethical Review Committee (reference: 2022.0817—NL83111.029.22). We will publish our findings in peer-reviewed international journals.Trial registration numberISRCTN97250704.
Identifying tests to evaluate in a diagnostic accuracy study for patients with vertigo in general practice: a Delphi study
Introduction Vertigo is a common symptom that strongly impacts patients’ quality of life. More than 80% of patients experiencing vertigo are primarily treated by their general practitioner (GP). The GP’s'diagnostic toolkit' for vertigo has serious limitations, though, because diagnostic accuracy studies on conditions that may cause vertigo have never been performed in a general practice setting. Our aim was to determine which tests should be investigated in a diagnostic accuracy study for patients with vertigo in general practice. Method We conducted an online Delphi procedure involving national and international experts. The experts were asked to judge a selection of 40 diagnostic tests based on the Dutch GP guideline on vestibular symptoms, supplemented by tests identified during a systematic review. Panellists were allowed to suggest additional tests after the first round. In case of consensus of at least 70%, a test was included or excluded. We also conducted a secondary sub-analysis of our Delphi procedure to demonstrate non-dominance of Dutch experts within our expert panel. Data were analysed using descriptive statistics and content analysis. Data were analysed using descriptive statistics and content analysis. Results A panel of 20 experts from five countries, including 7 specialists in otolaryngology, 6 neurologists and 7 GPs, participated in the Delphi procedure. The panel judged 46 diagnostic tests in total, with 6 additional tests added to the original selection based on suggestions by experts. After the first two rounds (100% response rate), 16 tests were included, 22 tests were excluded and no consensus was reached on 8 tests. During the consensus round, one of the 8 tests was added to the included 16 tests. Of these 17 tests, 15 are recommended by the Dutch GP guideline, supplemented by the non-recommended Tandem walking test and the Romberg test. Conclusions An international expert panel reached consensus on 17 tests for vertigo in general practice that should be investigated in a diagnostic accuracy study.
Clinical characteristics and survival patterns of subsequent sarcoma, breast cancer, and melanoma after childhood cancer in the DCOG-LATER cohort
Purpose Childhood cancer survivors are at increased risk of developing subsequent malignant neoplasms (SMNs). We compared survival and clinical characteristics of survivors with SMNs (sarcoma, breast cancer, or melanoma) and a population-based sample of similar first malignant neoplasm (FMN) patients. Methods We assembled three case series of solid SMNs observed in a cohort of 5-year Dutch childhood cancer survivors diagnosed 1963–2001 and followed until 2014: sarcoma ( n  = 45), female breast cancer ( n  = 41), and melanoma ( n  = 17). Each SMN patient was sex-, age-, and calendar year-matched to 10 FMN patients in the population-based Netherlands Cancer Registry. We compared clinical and histopathological characteristics by Fisher’s exact tests and survival by multivariable Cox regression and competing risk regression analyses. Results Among sarcoma-SMN patients, overall survival [hazard ratio (HR) 1.88, 95% confidence interval (CI) 1.23–2.87] and sarcoma-specific mortality (HR 1.91, 95% CI 1.16–3.13) were significantly worse compared to sarcoma-FMN patients (foremost for soft-tissue sarcoma), with 15-year survival rates of 30.8% and 61.6%, respectively. Overall survival did not significantly differ for breast-SMN versus breast-FMN patients (HR 1.14, 95% CI 0.54–2.37), nor for melanoma-SMN versus melanoma-FMN patients (HR 0.71, 95% CI 0.10–5.00). No significant differences in tumor characteristics were observed between breast-SMN and breast-FMN patients. Breast-SMN patients were treated more often with mastectomy without radiotherapy/chemotherapy compared to breast-FMN patients (17.1% vs. 5.6%). Conclusions Survival of sarcoma-SMN patients is worse than sarcoma-FMN patients. Although survival and tumor characteristics appear similar for breast-SMN and breast-FMN patients, treatment differs; breast-SMN patients less often receive breast-conserving therapy. Larger studies are necessary to substantiate these exploratory findings.