TY - JOUR A1 - Brockhaus, Moritz K. A1 - Behbahani, Mehdi A1 - Muris, Farina A1 - Jansen, Sebastian V. A1 - Schmitz- Rode, Thomas A1 - Steinseifer, Ulrich A1 - Clauser, Johanna C. T1 - In vitro thrombogenicity testing of pulsatile mechanical circulatory support systems: Design and proof-of-concept JF - Artificial Organs N2 - Thrombogenic complications are a main issue in mechanical circulatory support (MCS). There is no validated in vitro method available to quantitatively assess the thrombogenic performance of pulsatile MCS devices under realistic hemodynamic conditions. The aim of this study is to propose a method to evaluate the thrombogenic potential of new designs without the use of complex in-vivo trials. This study presents a novel in vitro method for reproducible thrombogenicity testing of pulsatile MCS systems using low molecular weight heparinized porcine blood. Blood parameters are continuously measured with full blood thromboelastometry (ROTEM; EXTEM, FIBTEM and a custom-made analysis HEPNATEM). Thrombus formation is optically observed after four hours of testing. The results of three experiments are presented each with two parallel loops. The area of thrombus formation inside the MCS device was reproducible. The implantation of a filter inside the loop catches embolizing thrombi without a measurable increase of platelet activation, allowing conclusions of the place of origin of thrombi inside the device. EXTEM and FIBTEM parameters such as clotting velocity (α) and maximum clot firmness (MCF) show a total decrease by around 6% with a characteristic kink after 180 minutes. HEPNATEM α and MCF rise within the first 180 minutes indicate a continuously increasing activation level of coagulation. After 180 minutes, the consumption of clotting factors prevails, resulting in a decrease of α and MCF. With the designed mock loop and the presented protocol we are able to identify thrombogenic hot spots inside a pulsatile pump and characterize their thrombogenic potential. Y1 - 2021 U6 - http://dx.doi.org/10.1111/aor.14046 SN - 1525-1594 VL - 45 IS - 12 SP - 1513 EP - 1521 PB - Wiley CY - Weinheim ER - TY - CHAP A1 - Richter, Charlotte A1 - Braunstein, Bjoern A1 - Stäudle, Benjamin A1 - Attias, Julia A1 - Suess, Alexander A1 - Weber, T. A1 - Rittweger, Joern A1 - Green, David A. A1 - Albracht, Kirsten T1 - In vivo fascicle length of the gastrocnemius muscle during walking in simulated martian gravity using two different body weight support devices T2 - 23rd Annual Congress of the European College of Sport Science, Dublin, Irland Y1 - 2018 ER - TY - JOUR A1 - Digel, Ilya T1 - In-situ biological decontamination of an ice melting probe Y1 - 2010 N1 - 38th COSPAR Scientific Assembly. Held 18-15 July 2010, in Bremen, Germany Abstract unter https://www.cospar-assembly.org/abstractcd/OLD/COSPAR-10/abstracts/data/pdf/abstracts/F36-0013-10.pdf ER - TY - CHAP A1 - Digel, Ilya A1 - Leimena, W. A1 - Dachwald, Bernd A1 - Linder, Peter A1 - Porst, Dariusz A1 - Kayser, Peter A1 - Funke, O. A1 - Temiz Artmann, Aysegül A1 - Artmann, Gerhard T1 - In-situ biological decontamination of an ice melting probe : [abstract] N2 - The objective of our study was to investigate the efficacy of different in-situ decontamination protocols in the conditions of thermo-mechanical ice-melting. KW - Sonde KW - Dekontamination KW - Wasserstoffperoxid KW - Natriumhypochlorit Y1 - 2010 ER - TY - JOUR A1 - Heinzel, Alexander A1 - Schäfer, Ralf A1 - Müller, Hans-Wilhelm A1 - Schieffer, Andre A1 - Ingenhag, Ariane A1 - Eickhoff, Simon B. A1 - Northoff, Georg A1 - Franz, Matthias A1 - Hautzel, Hubertus T1 - Increased Activation of the Supragenual Anterior Cingulate Cortex during Visual Emotional Processing in Male Subjects with High Degrees of Alexithymia: An Event-Related fMRI Study JF - Psychotherapy and Psychosomatics N2 - Background: One of the most prominent neurobiological models of alexithymia assumes an altered function of the anterior cingulate cortex (ACC) as the crucial neural correlate of alexithymia. So far functional imaging studies have yielded inconclusive results. Therefore, we tested this hypothesis in healthy alexithymics and nonalexithymics in an event-related fMRI study. Methods: Thirty high- and 30 low-alexithymic right-handed male subjects (selected by the 20-item Toronto Alexithymia Scale, TAS-20) were investigated with event-related fMRI using a picture viewing paradigm. The stimuli consisted of happy, fearful and neutral facial expressions (Ekman-Friesen) as well as positive, negative and neutral pictures from the International Affective Picture System. Results: Contrasting the high-alexithymic with the low-alexithymic group we observed increased activation of the supragenual ACC for different emotional valences as well as for different emotional stimuli. Moreover, there was a positive correlation of the ACC with the individual TAS-20 scores but no correlations with the individual Beck Depression Inventory scores. Additionally, there was no difference in activity of the amygdala. Conclusions: We demonstrated that the supragenual ACC is constantly activated more strongly in alexithymic subjects and that this activation is related to the symptoms of alexithymia and not to associated symptoms such as depression. Therefore, our findings support the hypothesis of an altered function of the ACC in alexithymia. Y1 - 2010 U6 - http://dx.doi.org/10.1159/000320121 SN - 0033-3190 VL - 79 IS - 6 SP - 363 EP - 370 PB - Karger CY - Basel ER - TY - JOUR A1 - Heinke, Lars N. A1 - Knicker, Axel J. A1 - Albracht, Kirsten T1 - Increased shoulder muscle stretch reflex elicitability in supine subject posture JF - Isokinetics and Exercise Science N2 - BACKGROUND: Muscle stretch reflexes are widely used to examine neural muscle function. The knowledge of reflex response in muscles crossing the shoulder is limited. OBJECTIVE: To quantify reflex modulation according to various subject postures and different procedures of muscle pre-activation steering. METHODS: Thirteen healthy male participants performed two sets of external shoulder rotation stretches in various positions and with different procedures of muscle pre-activation steering on an isokinetic dynamometer over a range of two different pre-activation levels. All stretches were applied with a dynamometer acceleration of 104∘/s2 and a velocity of 150∘/s. Electromyographical response was measured via sEMG. RESULTS: Consistent reflexive response was observed in all tested muscles in all experimental conditions. The reflex elicitation rate revealed a significant muscle main effect (F (5,288) = 2.358, ρ= 0.040; η2= 0.039; f= 0.637) and a significant test condition main effect (F (1,288) = 5.884, ρ= 0.016; η2= 0.020; f= 0.143). Reflex latency revealed a significant muscle pre-activation level main effect (F (1,274) = 5.008, ρ= 0.026; η2= 0.018; f= 0.469). CONCLUSION: Muscular reflexive response was more consistent in the primary internal rotators of the shoulder. Supine posture in combination with visual feedback of muscle pre-activation level enhanced the reflex elicitation rate. Y1 - 2020 U6 - http://dx.doi.org/10.3233/IES-192219 SN - 1878-5913 VL - 28 IS - 2 SP - 139 EP - 146 PB - IOS Press CY - Amsterdam ER - TY - JOUR A1 - Nguyen, Nhu Huynh A1 - Duong, Minh Tuan A1 - Tran, Thanh Ngoc A1 - Pham, Phu Tinh A1 - Grottke, O. A1 - Tolba, R. A1 - Staat, Manfred T1 - Influence of a freeze–thaw cycle on the stress–stretch curves of tissues of porcine abdominal organs JF - Journal of Biomechanics N2 - The paper investigates both fresh porcine spleen and liver and the possible decomposition of these organs under a freeze–thaw cycle. The effect of tissue preservation condition is an important factor which should be taken into account for protracted biomechanical tests. In this work, tension tests were conducted for a large number of tissue specimens from twenty pigs divided into two groups of 10. Concretely, the first group was tested in fresh state; the other one was tested after a freeze-thaw cycle which simulates the conservation conditions before biomechanical experiments. A modified Fung model for isotropic behavior was adopted for the curve fitting of each kind of tissues. Experimental results show strong effects of the realistic freeze–thaw cycle on the capsule of elastin-rich spleen but negligible effects on the liver which virtually contains no elastin. This different behavior could be explained by the autolysis of elastin by elastolytic enzymes during the warmer period after thawing. Realistic biomechanical properties of elastin-rich organs can only be expected if really fresh tissue is tested. The observations are supported by tests of intestines. KW - Autolysis KW - Decomposition KW - Freeze–thaw process KW - Spleen KW - Liver Y1 - 2012 U6 - http://dx.doi.org/10.1016/j.jbiomech.2012.07.008 SN - 1873-2380 VL - 45 IS - 14 SP - 2382 EP - 2386 PB - Elsevier CY - Amsterdam ER - TY - THES A1 - Albracht, Kirsten T1 - Influence of mechanical properties of the leg extensor muscletendon units on running economy Y1 - 2010 N1 - Cologne, German Sport Univ., Diss., 2010 PB - Deutsche Sporthochschule Köln CY - Köln ER - TY - JOUR A1 - Duong, Minh Tuan A1 - Nguyen, Nhu Huynh A1 - Tran, Thanh Ngoc A1 - Tolba, R. H. A1 - Staat, Manfred T1 - Influence of refrigerated storage on tensile mechanical properties of porcine liver and spleen JF - International biomechanics Y1 - 2015 U6 - http://dx.doi.org/10.1080/23335432.2015.1049295 SN - 2333-5432 VL - Vol. 2 IS - Iss. 1 SP - 79 EP - 88 PB - Taylor & Francis CY - London ER - TY - JOUR A1 - Lenz, Maximilian A1 - Kahmann, Stephanie Lucina A1 - Behbahani, Mehdi A1 - Pennig, Lenhard A1 - Hackl, Michael A1 - Leschinger, Tim A1 - Müller, Lars Peter A1 - Wegmann, Kilian T1 - Influence of rotator cuff preload on fracture configuration in proximal humerus fractures: a proof of concept for fracture simulation JF - Archives of Orthopaedic and Trauma Surgery N2 - Introduction In regard of surgical training, the reproducible simulation of life-like proximal humerus fractures in human cadaveric specimens is desirable. The aim of the present study was to develop a technique that allows simulation of realistic proximal humerus fractures and to analyse the influence of rotator cuff preload on the generated lesions in regards of fracture configuration. Materials and methods Ten cadaveric specimens (6 left, 4 right) were fractured using a custom-made drop-test bench, in two groups. Five specimens were fractured without rotator cuff preload, while the other five were fractured with the tendons of the rotator cuff preloaded with 2 kg each. The humeral shaft and the shortened scapula were potted. The humerus was positioned at 90° of abduction and 10° of internal rotation to simulate a fall on the elevated arm. In two specimens of each group, the emergence of the fractures was documented with high-speed video imaging. Pre-fracture radiographs were taken to evaluate the deltoid-tuberosity index as a measure of bone density. Post-fracture X-rays and CT scans were performed to define the exact fracture configurations. Neer’s classification was used to analyse the fractures. Results In all ten cadaveric specimens life-like proximal humerus fractures were achieved. Two III-part and three IV-part fractures resulted in each group. The preloading of the rotator cuff muscles had no further influence on the fracture configuration. High-speed videos of the fracture simulation revealed identical fracture mechanisms for both groups. We observed a two-step fracture mechanism, with initial impaction of the head segment against the glenoid followed by fracturing of the head and the tuberosities and then with further impaction of the shaft against the acromion, which lead to separation of the tuberosities. Conclusion A high energetic axial impulse can reliably induce realistic proximal humerus fractures in cadaveric specimens. The preload of the rotator cuff muscles had no influence on initial fracture configuration. Therefore, fracture simulation in the proximal humerus is less elaborate. Using the presented technique, pre-fractured specimens are available for real-life surgical education. KW - Proximal humerus fracture KW - Biomechanical simulation KW - Fracture configuration KW - Fracture simulation KW - Rotator cuff Y1 - 2022 U6 - http://dx.doi.org/10.1007/s00402-022-04471-9 SN - 1434-3916 PB - Springer CY - Berlin, Heidelberg ER -