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Your search keyword '"Christian Witzel"' showing total 4 results
4 results on '"Christian Witzel"'

1. Moderate LMWH Anticoagulation Improves Success Rate of Hind Limb Allotransplantation in Mice

Author

Barbara Kern, MD, Muhammad-Imtiaz Ashraf, PhD, Anja Reutzel-Selke, PhD, Joerg Mengwasser, PhD, Dietrich Polenz, Edward Michaelis, MD, Johann Pratschke, MD, PhD, Stefan G. Tullius, MD, PhD, Christian Witzel, MD, PhD, and Igor M. Sauer, MD, PhD

Subjects
Surgery, RD1-811
Abstract

Background:. The mouse hind limb model represents a powerful research tool in vascularized composite tissue allotransplantation, but its applicability is limited due to poor graft survival (62%–83%). Vascular thrombosis and massive hemorrhage are the major causes for these drop-outs. We hypothesize that because of better anticoagulation effect and lower risk of thrombocytopenia, application of low molecular weight heparin (LMWH) will minimize vascular complications and enhance graft and animal survival. Methods:. Fifty allogeneic hind limb transplantations were performed (C57BL/6 to DBA/2 mice) using five different anticoagulation protocols. Bleeding and thromboembolic events were recorded macroscopically by postoperative hemorrhage and livid discoloration of the graft, respectively. Graft perfusion and survival were monitored daily by capillary-refill-time of graft toes within 2–3 seconds. Vascular congestion and tissue necrosis were examined by histological evaluation of hematoxylin-eosin-stained tissue sections. Results:. All transplantations were technically successful. Increase in thromboembolic events and a concomitant decrease in bleeding events were observed with the decreasing concentration of heparin in the perfusion solution. Although treatment of donor and recipient with low dose of LMWH could not reduce thromboembolic events, moderate dose effectively reduced these events. Compared with the poor outcome of graft perfusion with heparin alone, additional treatment of donor and recipient with low dose of LMWH improved graft and animal survival by 18%. Interestingly, animals treated with moderate dose of LMWH demonstrated 100% graft and animal survival. Conclusions:. Treatment of donor and recipient mice with a moderate dose of LMWH prevents vascular complications and improves the outcome of murine hind limb transplants.

Published
2023
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2. Hepatic artery reconstruction using an operating microscope in pediatric liver transplantation—Is it worth the effort?

Author

Safak Gül-Klein, Maximilian Jara, Stephan Henning, Johann Pratschke, Philipp Bufler, Robert Öllinger, Wenzel Schöning, Paul Viktor Ritschl, Moritz Schmelzle, Brigitta Globke, Christian Witzel, Tomasz Dziodzio, Karl-Herbert Hillebrandt, Alexander Gratopp, Georgios Koulaxouzidis, Uli Fehrenbach, Maximilian Nösser, and Friederike Martin

Subjects
Male, medicine.medical_specialty, medicine.medical_treatment, Liver transplantation, surgical loupes, Hepatic Artery, Risk Factors, parasitic diseases, medicine, Clinical endpoint, Humans, hepatic artery thrombosis, Child, Adverse effect, Transplantation, business.industry, Incidence (epidemiology), hepatic artery reconstruction, Graft Survival, Infant, Thrombosis, Plastic Surgery Procedures, Liver Transplantation, Surgery, Survival Rate, Hepatic artery thrombosis, operating microscope, pediatric liver transplantation, Child, Preschool, Pediatrics, Perinatology and Child Health, Cohort, Female, Artery reconstruction, business, Operating microscope, Vascular Surgical Procedures, 600 Technik, Medizin, angewandte Wissenschaften::610 Medizin und Gesundheit::610 Medizin und Gesundheit
Abstract

Introduction: In pediatric liver transplantation (pLT), hepatic artery thrombosis (HAT) is associated with inferior transplant outcome. Hepatic artery reconstruction (HAR) using an operating microscope (OM) is considered to reduce the incidence of HAT. Methods: HAR using an OM was compared to a historic cohort using surgical loupes (SL) in pLT performed between 2009 and 2020. Primary endpoint was the occurrence of HAT. Secondary endpoints were 1-year patient and graft survival determined by Kaplan-Meier analysis and complications. Multivariate analysis was used to identify independent risk factors for HAT and adverse events. Results: A total of 79 pLTs were performed [30 (38.0%) living donations; 49 (62.0%) postmortem donations] divided into 23 (29.1%) segment 2/3, 32 (40.5%) left lobe, 4 (5.1%) extended right lobe, and 20 (25.3%) full-size grafts. One-year patient and graft survival were both 95.2% in the OM group versus 86.2% and 77.8% in the SL group (p = .276 and p = .077). HAT rate was 0% in the OM group versus 24.1% in the SL group (p = .013). One-year patient and graft survival were 64.3% and 35.7% in patient with HAT, compared to 93.9% and 92.8% in patients with no HAT (both p < .001). Multivariate analysis revealed HAR with SL (p = .022) and deceased donor liver transplantation (DDLT) (p = .014) as independent risk factors for HAT. The occurrence of HAT was independently associated with the need for retransplantation (p < .001) and biliary leakage (p = .045). Conclusion: In pLT, the use of an OM is significantly associated to reduce HAT rate, biliary complications, and graft loss and outweighs the disadvantages of delayed arterial perfusion and prolonged warm ischemia time (WIT).

Published
2021

3. A self-made, low-cost infrared system for evaluating the sciatic functional index in mice

Author

Georgios Koulaxouzidis, G. Bjoern Stark, Florian Lampert, Christian Witzel, Vincenzo Penna, and Lukas Fricker

Subjects
0301 basic medicine, medicine.medical_specialty, crush, Sciatic functional index, sciatic nerve, error rate, lcsh:RC346-429, Standard deviation, Sham group, 03 medical and health sciences, Reference test, 0302 clinical medicine, Sciatic nerve crush, Developmental Neuroscience, Peripheral nerve, Evaluation methods, medicine, peripheral nerve injury, frustrated total internal reflection, nerve regeneration, lcsh:Neurology. Diseases of the nervous system, mouse, Mathematics, Surgery, 030104 developmental biology, ladder beam walking test, 600 Technik, Medizin, angewandte Wissenschaften::610 Medizin und Gesundheit::617 Chirurgie und verwandte medizinische Einrichtungen, infrared, Sciatic nerve, neural regeneration, 030217 neurology & neurosurgery, Research Article, Biomedical engineering
Abstract

The sciatic functional index (SFI) is a popular parameter for peripheral nerve evaluation that relies on footprints obtained with ink and paper. Drawbacks include smearing artefacts and a lack of dynamic information during measurement. Modern applications use digitized systems that can deliver results with less analytical effort and fewer mice. However, the systems are expensive (€40,000). This study aimed to evaluate the applicability and precision of a self-made, low-cost infrared system for evaluating SFI in mice. Mice were subjected to unilateral sciatic nerve crush injury (crush group; n = 7) and sham operation (sham group; n = 4). They were evaluated on the day before surgery, the 2(nd), 4(th) and 6(th) days after injury, and then every day up to the 23(rd) day after injury. We compared two SFI evaluation methods, i.e., conventional ink-and-paper SFI (C-SFI) and our infrared system (I-SFI). Our apparatus visualized footprints with totally internally reflected infrared light (950 nm) and a camera that can only detect this wavelength. Additionally we performed an analysis with the ladder beam walking test (LBWT) as a reference test. I-SFI assessment reduced the standard deviation by about 33 percent, from 11.6 to 7.8, and cut the variance around the baseline to 21 percent. The system thus requires fewer measurement repetitions and fewer animals, and cuts the cost of keeping the animals. The apparatus cost €321 to build. Our results show that the process of obtaining the SFI can be made more precise via digitization with a self-made, low-cost infrared system.

Published
2016

4. Charite University Hospital and School of Medicine Researchers Update Current Study Findings on Thrombocytopenia (Moderate LMWH Anticoagulation Improves Success Rate of Hind Limb Allotransplantation in Mice).

Subjects
HINDLIMB, UNIVERSITY hospitals, RESEARCH personnel, THROMBOCYTOPENIA, BLOOD platelet disorders
Abstract

A study conducted by researchers at Charite University Hospital and School of Medicine in Berlin, Germany, has found that moderate low molecular weight heparin (LMWH) anticoagulation improves the success rate of hind limb allotransplantation in mice. The researchers performed fifty allogeneic hind limb transplantations using different anticoagulation protocols and found that treatment with a moderate dose of LMWH reduced thromboembolic events and improved graft and animal survival. The study suggests that LMWH could be used to prevent vascular complications in hind limb transplants. [Extracted from the article]

Published
2024

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