TY - JOUR A1 - Baroud, G. A1 - Wu, J.Z. A1 - Bohner, M A1 - Sponagel, Stefan A1 - Steffen, T. T1 - How to determine the permeability for cement infiltration into osteoporotic cancellous bone JF - Medical Engineering & Physics. 25 (2003), H. 4 N2 - Cement augmentation is an emerging surgical procedure in which bone cement is used to infiltrate and reinforce osteoporotic vertebrae. Although this infiltration procedure has been widely applied, it is performed empirically and little is known about the flow characteristics of cement during the injection process. We present a theoretical and experimental approach to investigate the intertrabecular bone permeability during the infiltration procedure. The cement permeability was considered to be dependent on time, bone porosity, and cement viscosity in our analysis. In order to determine the time-dependent permeability, ten cancellous bone cores were harvested from osteoporotic vertebrae, infiltrated with acrylic cement at a constant flow rate, and the pressure drop across the cores during the infiltration was measured. The viscosity dependence of the permeability was determined based on published experimental data. The theoretical model for the permeability as a function of bone porosity and time was then fit to the testing data. Our findings suggest that the intertrabecular bone permeability depends strongly on time. For instance, the initial permeability (60.89 mm4/N.s) reduced to approximately 63% of its original value within 18 seconds. This study is the first to analyze cement flow through osteoporotic bone. The theoretical and experimental models provided in this paper are generic. Thus, they can be used to systematically study and optimize the infiltration process for clinical practice. KW - Osteoporose KW - Permeabilität KW - Viskose Strömung KW - Viskosität KW - Vertebroplastie KW - Cement infiltration KW - Vertebroplasty KW - Osteoporosis KW - Permeability KW - Experiment KW - Analysis KW - Viscous flow Y1 - 2003 SN - 1350-4533 SP - 283 EP - 288 ER - TY - JOUR A1 - Artmann, Gerhard A1 - Gorbatenkova, E. A. A1 - Panasenko, O. M. T1 - Hypochlorous acid and human blood low density lipoproteins modified by hypochlorous acid increase erythrocyte adhesion to endothelial cells. Gorbatenkova, E. A.; Artmann, Gerhard Michael; Panasenko, O. M. JF - Membrane and cell biology. 13 (2000), H. 4 Y1 - 2000 SN - 1023-6597 SP - 537 EP - 546 ER - TY - JOUR A1 - Doorschodt, B. M. A1 - Schreinemachers, M. C. J. M. A1 - Behbahani, Mehdi A1 - Florquin, S. A1 - Weis, J. A1 - Staat, Manfred A1 - Tolba, R. H. T1 - Hypothermic machine perfusion of kidney grafts: which pressure is preferred JF - Annals of Biomedical Engineering. 39 (2011), H. 3 Y1 - 2011 SN - 1573-9686 SP - 1051 EP - 1059 PB - Springer CY - Berlin ER - TY - JOUR A1 - Sponagel, Stefan A1 - Unger, J. A1 - Spies, K. H. T1 - Härtebegriff im Zusammenhang mit Vernetzung, Bruchdehnung und Dauerfestigkeit eines Elastomers JF - Kautschuk Gummi Kunststoffe. 56 (2003), H. 11 Y1 - 2003 SN - 0948-3276 SP - 608 EP - 613 ER - TY - JOUR A1 - Dachwald, Bernd A1 - Mikucki, Jill A1 - Tulaczyk, Slawek A1 - Digel, Ilya A1 - Espe, Clemens A1 - Feldmann, Marco A1 - Francke, Gero A1 - Kowalski, Julia A1 - Xu, Changsheng T1 - IceMole : A maneuverable probe for clean in situ analysis and sampling of subsurface ice and subglacial aquatic ecosystems JF - Annals of Glaciology N2 - There is significant interest in sampling subglacial environments for geobiological studies, but they are difficult to access. Existing ice-drilling technologies make it cumbersome to maintain microbiologically clean access for sample acquisition and environmental stewardship of potentially fragile subglacial aquatic ecosystems. The IceMole is a maneuverable subsurface ice probe for clean in situ analysis and sampling of glacial ice and subglacial materials. The design is based on the novel concept of combining melting and mechanical propulsion. It can change melting direction by differential heating of the melting head and optional side-wall heaters. The first two prototypes were successfully tested between 2010 and 2012 on glaciers in Switzerland and Iceland. They demonstrated downward, horizontal and upward melting, as well as curve driving and dirt layer penetration. A more advanced probe is currently under development as part of the Enceladus Explorer (EnEx) project. It offers systems for obstacle avoidance, target detection, and navigation in ice. For the EnEx-IceMole, we will pay particular attention to clean protocols for the sampling of subglacial materials for biogeochemical analysis. We plan to use this probe for clean access into a unique subglacial aquatic environment at Blood Falls, Antarctica, with return of a subglacial brine sample. KW - Antarctic Glaciology KW - Extraterrestrial Glaciology KW - Glaciological instruments and methods KW - Subclacial exploration KW - Subglacial lakes Y1 - 2014 U6 - http://dx.doi.org/10.3189/2014AoG65A004 SN - 1727-5644 VL - 55 IS - 65 SP - 14 EP - 22 PB - Cambridge University Press CY - Cambridge ER - TY - JOUR A1 - Werfel, Stanislas A1 - Günthner, Roman A1 - Hapfelmeier, Alexander A1 - Hanssen, Henner A1 - Kotliar, Konstantin A1 - Heemann, Uwe A1 - Schmaderer, Christoph ED - Guzik, Tomasz J. T1 - Identification of cardiovascular high-risk groups from dynamic retinal vessel signals using untargeted machine learning JF - Cardiovascular Research N2 - Dynamic retinal vessel analysis (DVA) provides a non-invasive way to assess microvascular function in patients and potentially to improve predictions of individual cardiovascular (CV) risk. The aim of our study was to use untargeted machine learning on DVA in order to improve CV mortality prediction and identify corresponding response alterations. KW - Machine learning KW - Retinal vessels KW - Microcirculation KW - Haemodialysis KW - Myocardial infarction and cardiac death Y1 - 2022 U6 - http://dx.doi.org/10.1093/cvr/cvab040 SN - 0008-6363 VL - 118 IS - 2 SP - 612 EP - 621 PB - Oxford University Press CY - Oxford ER - TY - JOUR A1 - Bogoyavlenskiy, A. P. A1 - Berezin, V. E. A1 - Ogneva, A. V. A1 - Tolmacheva, V. P. A1 - Digel, Ilya A1 - Khudyakova, S. S. T1 - Immunostimulating activity of a saponin-containing extract of Saponaria officinalis JF - Voprosy virusologii Y1 - 1999 SN - 0507-4088 VL - 44 IS - 5 SP - 229 EP - 232 ER - TY - JOUR A1 - Dachwald, Bernd A1 - McDonald, Malcolm A1 - McInnes, Colin R. A1 - Mengali, Giovanni T1 - Impact of Optical Degradation on Solar Sail Mission Performance JF - Journal of Spacecraft and Rockets. 44 (2007), H. 4 Y1 - 2007 SN - 0022-4650 N1 - 2. ISSN: 1533-6794 SP - 740 EP - 749 ER - TY - JOUR A1 - Temiz Artmann, Aysegül A1 - Resmi, Halil A1 - Akhunlar, Hülya A1 - Güner, Gül T1 - In vitro effects of high glucose concentrations on membrane protein sulfhydryl oxidation, G-actin and deformability of human erythrocytes. Resmi, Halil ; Akhunlar, Hülya ; Temiz Artmann, Aysegül ; Güner, Gül JF - Cell biochemistry and function. 23 (2005), H. 3 Y1 - 2005 SN - 0263-6484 SP - 163 EP - 168 ER - TY - JOUR A1 - Temiz Artmann, Aysegül A1 - Baskurt, O. K. A1 - Edremitlioglu, M. T1 - In vitro effects of in vivo activated leukocytes on red blood cell filterability and lipid peroxidation. Baskurt, O.K.; Edremitlioglu, M.; Temiz, A. JF - Clinical Hemorheology. 14 (1994), H. 4 Y1 - 1994 SP - 591 EP - 596 ER - 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 - 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 - 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 - JOUR A1 - Artmann, Gerhard A1 - Schmid-Schönbein, H. A1 - Schröder, Susanne A1 - Grebe, R. [u.a.] T1 - Influence of Moxaverine-HCL on Membrane Curvature and Microsieve Filterability of Red Cells after Exposure to Hyperosmolarity and Lactacidosis. Schmid-Schönbein, H.; Schröder, Susanne; Grebe, R.; Artmann, Gerhard Michael, Eschweiler, H; Teitel, P. JF - Arzneimittelforschung. 38 (1988), H. 5 Y1 - 1988 SN - 0004-4172 SP - 710 EP - 716 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 - TY - JOUR A1 - Kopp, Alexander A1 - Schunck, Laura A1 - Gosau, Martin A1 - Smeets, Ralf A1 - Burg, Simon A1 - Fuest, Sandra A1 - Kröger, Nadja A1 - Zinser, Max A1 - Krohn, Sebastian A1 - Behbahani, Mehdi A1 - Köpf, Marius A1 - Lauts, Lisa A1 - Rutkowski, Rico T1 - Influence of the casting concentration on the mechanical and optical properties of Fa/CaCl2-derived silk fibroin membranes JF - International Journal of Molecular Sciences N2 - In this study, we describe the manufacturing and characterization of silk fibroin membranes derived from the silkworm Bombyx mori. To date, the dissolution process used in this study has only been researched to a limited extent, although it entails various potential advantages, such as reduced expenses and the absence of toxic chemicals in comparison to other conventional techniques. Therefore, the aim of this study was to determine the influence of different fibroin concentrations on the process output and resulting membrane properties. Casted membranes were thus characterized with regard to their mechanical, structural and optical assets via tensile testing, SEM, light microscopy and spectrophotometry. Cytotoxicity was evaluated using BrdU, XTT, and LDH assays, followed by live–dead staining. The formic acid (FA) dissolution method was proven to be suitable for the manufacturing of transparent and mechanically stable membranes. The fibroin concentration affects both thickness and transparency of the membranes. The membranes did not exhibit any signs of cytotoxicity. When compared to other current scientific and technical benchmarks, the manufactured membranes displayed promising potential for various biomedical applications. Further research is nevertheless necessary to improve reproducible manufacturing, including a more uniform thickness, less impurity and physiological pH within the membranes. Y1 - 2020 U6 - http://dx.doi.org/10.3390/ijms21186704 SN - 1422-0067 N1 - Special issue: Optimization of Biomaterials for Reconstructive and Regenerative Medicine VL - 21 IS - 18 art. no. 6704 PB - MDPI CY - Basel ER - TY - JOUR A1 - Albracht, Kirsten A1 - Arampatzis, Adamantios T1 - Influence of the mechanical properties of the muscle-tendon unit on force generation in runners with different running economy JF - Biological Cybernetics Y1 - 2006 U6 - http://dx.doi.org/10.1007/s00422-006-0070-z SN - 1432-0770 VL - 95 IS - 1 SP - 87 EP - 96 ER - TY - JOUR A1 - Artmann, Gerhard A1 - Zhou-Stache, J. A1 - Buettner, R. A1 - Mittermayer, C. [u.a.] T1 - Inhibition of TNF-alpha induced cell death in HUVEC and Jurkat cells by protocatechuic acid. Zhou-Stache, J.; Buettner, R.; Artmann, Gerhard Michael; Mittermayer, C.; Bosserhoff, A. K. JF - Medical and Biological Engineering and Computing. 40 (2002), H. 6 Y1 - 2002 SN - 0140-0118 SP - 698 EP - 703 ER -