OPUS 4 | Medizin

Role of tristetraprolin in the resolution of inflammation (2021)

Peter Rappl Bernhard Brüne Tobias Schmid

Inflammation is a crucial part of immune responses towards invading pathogens or tissue damage. While inflammatory reactions are aimed at removing the triggering stimulus, it is important that these processes are terminated in a coordinate manner to prevent excessive tissue damage due to the highly reactive inflammatory environment. Initiation of inflammatory responses was proposed to be regulated predominantly at a transcriptional level, whereas post-transcriptional modes of regulation appear to be crucial for resolution of inflammation. The RNA-binding protein tristetraprolin (TTP) interacts with AU-rich elements in the 3′ untranslated region of mRNAs, recruits deadenylase complexes and thereby facilitates degradation of its targets. As TTP regulates the mRNA stability of numerous inflammatory mediators, it was put forward as a crucial post-transcriptional regulator of inflammation. Here, we summarize the current understanding of the function of TTP with a specific focus on its role in adding to resolution of inflammation.

Molecular mechanism of autosomal recessive long QT-syndrome 1 without deafness (2021)

Annemarie Oertli Susanne Rinné Robin Moss Stefan Kääb Gunnar Seemann Britt-Maria Beckmann Niels Decher

KCNQ1 encodes the voltage-gated potassium (Kv) channel KCNQ1, also known as KvLQT1 or Kv7.1. Together with its ß-subunit KCNE1, also denoted as minK, this channel generates the slowly activating cardiac delayed rectifier current IKs, which is a key regulator of the heart rate dependent adaptation of the cardiac action potential duration (APD). Loss-of-function mutations in KCNQ1 cause congenital long QT1 (LQT1) syndrome, characterized by a delayed cardiac repolarization and a prolonged QT interval in the surface electrocardiogram. Autosomal dominant loss-of-function mutations in KCNQ1 result in long QT syndrome, called Romano–Ward Syndrome (RWS), while autosomal recessive mutations lead to Jervell and Lange-Nielsen syndrome (JLNS), associated with deafness. Here, we identified a homozygous KCNQ1 mutation, c.1892_1893insC (p.P631fs*20), in a patient with an isolated LQT syndrome (LQTS) without hearing loss. Nevertheless, the inheritance trait is autosomal recessive, with heterozygous family members being asymptomatic. The results of the electrophysiological characterization of the mutant, using voltage-clamp recordings in Xenopus laevis oocytes, are in agreement with an autosomal recessive disorder, since the IKs reduction was only observed in homomeric mutants, but not in heteromeric IKs channel complexes containing wild-type channel subunits. We found that KCNE1 rescues the KCNQ1 loss-of-function in mutant IKs channel complexes when they contain wild-type KCNQ1 subunits, as found in the heterozygous state. Action potential modellings confirmed that the recessive c.1892_1893insC LQT1 mutation only affects the APD of homozygous mutation carriers. Thus, our study provides the molecular mechanism for an atypical autosomal recessive LQT trait that lacks hearing impairment.

Tracking of infused mesenchymal stem cells in injured pulmonary tissue in Atm-deficient mice (2020)

Patrick Baer Julia Sann Ruth Pia Dücker Evelyn Ullrich Helmut Geiger Peter Bader Stefan Zielen Ralf Schubert

Pulmonary failure is the main cause of morbidity and mortality in the human chromosomal instability syndrome Ataxia-telangiectasia (A-T). Major phenotypes include recurrent respiratory tract infections and bronchiectasis, aspiration, respiratory muscle abnormalities, interstitial lung disease, and pulmonary fibrosis. At present, no effective pulmonary therapy for A-T exists. Cell therapy using adipose-derived mesenchymal stromal/stem cells (ASCs) might be a promising approach for tissue regeneration. The aim of the present project was to investigate whether ASCs migrate into the injured lung parenchyma of Atm-deficient mice as an indication of incipient tissue damage during A-T. Therefore, ASCs isolated from luciferase transgenic mice (mASCs) were intravenously transplanted into Atm-deficient and wild-type mice. Retention kinetics of the cells were monitored using in vivo bioluminescence imaging (BLI) and completed by subsequent verification using quantitative real-time polymerase chain reaction (qRT-PCR). The in vivo imaging and the qPCR results demonstrated migration accompanied by a significantly longer retention time of transplanted mASCs in the lung parenchyma of Atm-deficient mice compared to wild type mice. In conclusion, our study suggests incipient damage in the lung parenchyma of Atm-deficient mice. In addition, our data further demonstrate that a combination of luciferase-based PCR together with BLI is a pivotal tool for tracking mASCs after transplantation in models of inflammatory lung diseases such as A-T.

Oil supplementation with a special combination of n-3 and n-6 long-chain polyunsaturated fatty acids does not protect for exercise induced asthma: a double-blind placebo-controlled trial (2020)

Melanie Dreßler Daniela Fußbroich Lisa Böhler Eva Herrmann Nicole Benker Markus Tytyk Johannes Schulze Ralf Schubert Christopher Beermann Stefan Zielen

Background: Many patients suffering from exercise-induced asthma (EIA) have normal lung function at rest and show symptoms and a decline in FEV1 when they do sports or during exercise-challenge. It has been described that long-chain polyunsaturated fatty acids (LCPUFA) could exert a protective effect on EIA. Methods: In this study the protective effect of supplementation with a special combination of n-3 and n-6 LCPUFA (sc-LCPUFA) (total 1.19 g/ day) were investigated in an EIA cold air provocation model. Primary outcome measure: Decrease in FEV1 after exercise challenge and secondary outcome measure: anti-inflammatory effects monitored by exhaled NO (eNO) before and after sc-LCPUFA supplementation versus placebo. Results: Ninety-nine patients with exercise-induced symptoms aged 10 to 45 were screened by a standardized exercise challenge in a cold air chamber at 4 °C. Seventy-three patients fulfilled the inclusion criteria of a FEV1 decrease > 15% and were treated double-blind placebo-controlled for 4 weeks either with sc-LCPUFA or placebo. Thirty-two patients in each group completed the study. Mean FEV1 decrease after cold air exercise challenge and eNO were unchanged after 4 weeks sc-LCPUFA supplementation. Conclusion: Supplementation with sc-LCPUFA at a dose of 1.19 g/d did not have any broncho-protective and anti-inflammatory effects on EIA. Trial registration: Clinical trial registration number: NCT02410096. Registered 7 February 2015 at Clinicaltrial.gov

Effect of total joint replacement in hip osteoarthritis on serum COMP and its correlation with mechanical-functional parameters of gait analysis (2020)

Elisa Endres Stefan van Drongelen Andrea Meurer Frank Zaucke Felix Stief

Objective: To study the effect of total hip replacement (THR) on serum cartilage oligomeric matrix protein concentration (sCOMP) and its correlation with joint loading during gait in patients with unilateral hip osteoarthritis. Design: In this prospective multimodal (clinical, biomechanical, biochemical) study blood samples from 15 patients were taken before and up to three times after THR (7 days, 3 months and 1 year), each after a resting period of at least 30 min, for analysis of sCOMP. Gait analysis was performed before and 1 year after THR to determine hip and knee joint moments. Results: Seven days after THR, sCOMP decreased significantly compared to the preoperative measurement (p < 0.001). Three months and 1 year postoperatively, sCOMP reverted to concentrations in the range of the preoperative value. One year postoperatively, a linear correlation between sCOMP and the maximum hip flexion moment was indicated in the first half of the stance phase on the unaffected side (r = −0.736, p = 0.024). No further correlations could be determined. Conclusions: Surprisingly, the removal of a joint affected by osteoarthritis did not have a sustained effect on sCOMP. Both before and after THR there was no scientifically substantiated correlation between sCOMP and joint moments from gait analysis. Consequently, the examination of sCOMP is not useful to detect altered joint loads that may influence degenerative changes of adjacent joints after THR. The registration number in the German Registry of Clinical Trials is DRKS00015053.

Curcumin - a viable agent for better bladder cancer treatment (2020)

Jochen Rutz Andrea Janicova Katja Woidacki Felix Chun Roman A. Blaheta Borna Relja

Although the therapeutic armamentarium for bladder cancer has considerably widened in the last few years, severe side eﬀects and the development of resistance hamper long-term treatment success. Thus, patients turn to natural plant products as alternative or complementary therapeutic options. One of these is curcumin, the principal component of Curcuma longa that has shown chemopreventive eﬀects in experimental cancer models. Clinical and preclinical studies point to its role as a chemosensitizer, and it has been shown to protect organs from toxicity induced by chemotherapy. These properties indicate that curcumin could hold promise as a candidate for additive cancer treatment. This review evaluates the relevance of curcumin as an integral part of therapy for bladder cancer.

Time course of traumatic neuroma development/role of electrical stimulation in inhibition of neuroma formation in a rat limb amputation model (2020)

Lukáš Pindur

Limb stump pain after amputation, due to sensitized neuromas, is a common condition that can cause a great deal of suffering in affected patients. Treatment is difficult, requiring a multidisciplinary approach that is often unsatisfactory. One treatment used to mitigate pain is electrical stimulation (EStim), administered using several different therapeutic approaches. The research described in this dissertation sought to characterize changes in peripheral nerve morphology, and neuroma formation, following limb amputation, with an eye toward developing better treatment strategies, that intervene before neuromas are fully formed. Another focus of this study was to evaluate the effect EStim has on changes in peripheral nerve morphology, and neuroma formation, following limb amputation. Right forelimbs of 42 male Sprague Dawley rats were amputated. At 3, 7, 28, 60 and 90 days post amputation (DPA) 6 limb stumps, in each group, were harvested and changes in peripheral nerve morphology, and neuroma formation were measured. In addition, limb stumps of 6 EStim treated, 6 sham-treated (deactivated EStim devices), and 6 non-treated rats were harvested at 28 DPA. Analysis revealed six distinct morphological characteristics of peripheral nerves during nerve regrowth and neuroma development; 1) normal nerve, 2) degenerating axons, 3) axonal sprouts, 4) unorganized bundles of axons in connective tissue, 5) unorganized axon growth into muscles, and 6) unorganized axon growth into fibrotic tissue (neuroma). At the early stages (3 & 7 DPA), normal nerves could be identified throughout the limb stump tissues and small areas of axonal sprouts were present near the distal tip of the stumps. Signs of degenerating axons were evident from 7 to 90 DPA. From day 28 on, variability of nerve characteristics, with signs of unorganized axon growth into muscle and fibrotic tissue, and neuroma formation, became visible in multiple areas of stump tissue. These pathological features became more evident at 60 and 90 DPA. EStim treated stumps revealed neuroma formation in 1 out of 6 animals, whereas in sham and controls, neuroma formation was seen in 4 out of 6 stumps respectively. We were able to identify 6 separate histological stages of peripheral nerve regrowth and neuroma formation over 90 days following amputation. Axonal regrowth was observed as early as 3 DPA, and signs of unorganized axonal growth and neuroma formation were evident by 28 DPA. Our observations suggest that EStim-based treatment and/or other prevention strategies might be more effective if administered in the initial dynamic stages of neuroma development.

Hemostatis analyzer-supported hemotherapy algorithm in cardiac surgery: protocol for a randomized controlled monocentric trial (2020)

Sophie Michel Florian Piekarski Jan-Hendrik Fischer Vanessa Hettler Elisabeth Hannah Adam Lars Holzer Gösta Lotz Thomas Walther Kai Zacharowski Florian Jürgen Raimann

Background: Point of care devices for performing targeted coagulation substitution in patients who are bleeding have become increasingly important in recent years. New on the market is the Quantra. It is a device that uses sonorheometry, a sonic estimation of elasticity via resonance, which is a novel ultrasound-based technology that measures viscoelastic properties of whole blood. Several studies have already shown the comparability of the Quantra with devices already established on the market, such as the rotational thromboelastometry (ROTEM) device. Objective: In contrast to existing studies, this study is the first prospective interventional study using this new system in a cardiac surgical patient cohort. We will investigate the noninferiority between an already existing coagulation algorithm based on the ROTEM/Multiplate system and a new algorithm based on the Quantra system for the treatment of coagulopathic cardiac surgical patients. Methods: The study is divided into two phases. In an initial observation phase, whole blood samples of 20 patients obtained at three defined time points (prior to surgery, after completion of cardiopulmonary bypass, and on arrival in the intensive care unit) will be analyzed using both the ROTEM/Multiplate and Quantra systems. The obtained threshold values will be used to develop a novel algorithm for hemotherapy. In a second intervention phase, the new algorithm will be tested for noninferiority against an algorithm used routinely for years in our department. Results: The main objective of the examination is the cumulative loss of blood within 24 hours after surgery. Statistical calculations based on the literature and in-house data suggest that the new algorithm is not inferior if the difference in cumulative blood loss is <150 mL/24 hours. Conclusions: Because of the comparability of the Quantra sonorheometry system with the ROTEM measurement methods, the existing hemotherapy treatment algorithm can be adapted to the Quantra device with proof of noninferiority. Trial Registration: ClinicalTrials.gov NCT03902275; https://clinicaltrials.gov/ct2/show/NCT03902275 International Registered Report Identifier (IRRID): DERR1-10.2196/17206

Regret among primary care physicians: a survey of diagnostic decisions (2020)

Beate S. Müller Norbert Donner-Banzhoff Martin Beyer Jörg Haasenritter Angelina Müller Carola Seifart

Background: Experienced and anticipated regret influence physicians’ decision-making. In medicine, diagnostic decisions and diagnostic errors can have a severe impact on both patients and physicians. Little empirical research exists on regret experienced by physicians when they make diagnostic decisions in primary care that later prove inappropriate or incorrect. The aim of this study was to explore the experience of regret following diagnostic decisions in primary care. Methods: In this qualitative study, we used an online questionnaire on a sample of German primary care physicians. We asked participants to report on cases in which the final diagnosis differed from their original opinion, and in which treatment was at the very least delayed, possibly resulting in harm to the patient. We asked about original and final diagnoses, illness trajectories, and the reactions of other physicians, patients and relatives. We used thematic analysis to assess the data, supported by MAXQDA 11 and Microsoft Excel 2016. Results: 29 GPs described one case each (14 female/15 male patients, aged 1.5–80 years, response rate < 1%). In 26 of 29 cases, the final diagnosis was more serious than the original diagnosis. In two cases, the diagnoses were equally serious, and in one case less serious. Clinical trajectories and the reactions of patients and relatives differed widely. Although only one third of cases involved preventable harm to patients, the vast majority (27 of 29) of physicians expressed deep feelings of regret. Conclusion: Even if harm to patients is unavoidable, regret following diagnostic decisions can be devastating for clinicians, making them ‘second victims’. Procedures and tools are needed to analyse cases involving undesirable diagnostic events, so that ‘true’ diagnostic errors, in which harm could have been prevented, can be distinguished from others. Further studies should also explore how physicians can be supported in dealing with such events in order to prevent them from practicing defensive medicine.

Recent advances in practical methods for liver cell biology: a short overview (2020)

Sandra Torres Zeinab Abdullah Maximilian J. Brol Claus Hellerbrand Mercedes Fernandez Romina Fiorotto Sabine Klein Philipp Königshofer Christian Liedtke Sophie Lotersztajn Yulia A. Nevzorova Robert Schierwagen Thomas Reiberger Frank Erhard Uschner Frank Tacke Ralf Weiskirchen Jonel Trebicka

Molecular and cellular research modalities for the study of liver pathologies have been tremendously improved over the recent decades. Advanced technologies offer novel opportunities to establish cell isolation techniques with excellent purity, paving the path for 2D and 3D microscopy and high-throughput assays (e.g., bulk or single-cell RNA sequencing). The use of stem cell and organoid research will help to decipher the pathophysiology of liver diseases and the interaction between various parenchymal and non-parenchymal liver cells. Furthermore, sophisticated animal models of liver disease allow for the in vivo assessment of fibrogenesis, portal hypertension and hepatocellular carcinoma (HCC) and for the preclinical testing of therapeutic strategies. The purpose of this review is to portray in detail novel in vitro and in vivo methods for the study of liver cell biology that had been presented at the workshop of the 8th meeting of the European Club for Liver Cell Biology (ECLCB-8) in October of 2018 in Bonn, Germany.

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