@article{RichterBraunsteinStaeudleetal.2021, author = {Richter, Charlotte and Braunstein, Bj{\"o}rn and St{\"a}udle, Benjamin and Attias, Julia and S{\"u}ss, Alexander and Weber, Tobias and Mileva, Katya N. and Rittweger, J{\"o}rn and Green, David A. and Albracht, Kirsten}, title = {Gastrocnemius medialis contractile behavior during running differs between simulated Lunar and Martian gravities}, series = {Scientific reports}, volume = {11}, journal = {Scientific reports}, number = {Article number: 22555}, publisher = {Springer Nature}, address = {London}, issn = {2045-2322}, doi = {10.1038/s41598-021-00527-9}, pages = {13 Seiten}, year = {2021}, abstract = {The international partnership of space agencies has agreed to proceed forward to the Moon sustainably. Activities on the Lunar surface (0.16 g) will allow crewmembers to advance the exploration skills needed when expanding human presence to Mars (0.38 g). Whilst data from actual hypogravity activities are limited to the Apollo missions, simulation studies have indicated that ground reaction forces, mechanical work, muscle activation, and joint angles decrease with declining gravity level. However, these alterations in locomotion biomechanics do not necessarily scale to the gravity level, the reduction in gastrocnemius medialis activation even appears to level off around 0.2 g, while muscle activation pattern remains similar. Thus, it is difficult to predict whether gastrocnemius medialis contractile behavior during running on Moon will basically be the same as on Mars. Therefore, this study investigated lower limb joint kinematics and gastrocnemius medialis behavior during running at 1 g, simulated Martian gravity, and simulated Lunar gravity on the vertical treadmill facility. The results indicate that hypogravity-induced alterations in joint kinematics and contractile behavior still persist between simulated running on the Moon and Mars. This contrasts with the concept of a ceiling effect and should be carefully considered when evaluating exercise prescriptions and the transferability of locomotion practiced in Lunar gravity to Martian gravity.}, language = {en} } @article{WerkhausenWillwacherAlbracht2021, author = {Werkhausen, Amelie and Willwacher, Steffen and Albracht, Kirsten}, title = {Medial gastrocnemius muscle fascicles shorten throughout stance during sprint acceleration}, series = {Scandinavian Journal of Medicine \& Science in Sports}, volume = {31}, journal = {Scandinavian Journal of Medicine \& Science in Sports}, number = {7}, publisher = {Wiley-Blackwell}, address = {Oxford}, issn = {0905-7188 (Druckausgabe)}, doi = {10.1111/sms.13956}, pages = {1471 -- 1480}, year = {2021}, abstract = {The compliant nature of distal limb muscle-tendon units is traditionally considered suboptimal in explosive movements when positive joint work is required. However, during accelerative running, ankle joint net mechanical work is positive. Therefore, this study aims to investigate how plantar flexor muscle-tendon behavior is modulated during fast accelerations. Eleven female sprinters performed maximum sprint accelerations from starting blocks, while gastrocnemius muscle fascicle lengths were estimated using ultrasonography. We combined motion analysis and ground reaction force measurements to assess lower limb joint kinematics and kinetics, and to estimate gastrocnemius muscle-tendon unit length during the first two acceleration steps. Outcome variables were resampled to the stance phase and averaged across three to five trials. Relevant scalars were extracted and analyzed using one-sample and two-sample t-tests, and vector trajectories were compared using statistical parametric mapping. We found that an uncoupling of muscle fascicle behavior from muscle-tendon unit behavior is effectively used to produce net positive mechanical work at the joint during maximum sprint acceleration. Muscle fascicles shortened throughout the first and second steps, while shortening occurred earlier during the first step, where negative joint work was lower compared with the second step. Elastic strain energy may be stored during dorsiflexion after touchdown since fascicles did not lengthen at the same time to dissipate energy. Thus, net positive work generation is accommodated by the reuse of elastic strain energy along with positive gastrocnemius fascicle work. Our results show a mechanism of how muscles with high in-series compliance can contribute to net positive joint work.}, language = {en} } @article{MontiWaldvogelRitzmannetal.2021, author = {Monti, Elena and Waldvogel, Janice and Ritzmann, Ramona and Freyler, Kathrin and Albracht, Kirsten and Helm, Michael and De Cesare, Niccol{\`o} and Pavan, Piero and Reggiani, Carlo and Gollhofer, Albert and Narici, Marco Vincenzo}, title = {Muscle in variable gravity: "I do not know where I am, but I know what to do"}, series = {Frontiers in Physiology}, volume = {12}, journal = {Frontiers in Physiology}, publisher = {Frontiers Research Foundation}, address = {Lausanne}, issn = {1664-042X}, doi = {10.3389/fphys.2021.714655}, pages = {19 Seiten}, year = {2021}, abstract = {Performing tasks, such as running and jumping, requires activation of the agonist and antagonist muscles before (motor unit pre-activation) and during movement performance (Santello and Mcdonagh, 1998). A well-timed and regulated muscle activation elicits a stretch-shortening cycle (SSC) response, naturally occurring in bouncing movements (Ishikawa and Komi, 2004; Taube et al., 2012). By definition, the SSC describes the stretching of a pre-activated muscle-tendon complex immediately followed by a muscle shortening in the concentric push-off phase (Komi, 1984). Given the importance of SSC actions for human movement, it is not surprising that many studies investigated the biomechanics of this phenomenon; in particular, drop jumps (DJs) represent a good paradigm to study muscle fascicle and tendon behavior in ballistic movements involving the SSC. Within a DJ, three main phases [pre-activation, braking, and push-off (PO; Komi, 2000)] have been recognized and extensively studied in common and challenging conditions, such as changes in load, falling height, or simulated hypo-gravity (Avela et al., 1994; Arampatzis et al., 2001; Fukashiro et al., 2005; Ishikawa et al., 2005; Sousa et al., 2007; Ritzmann et al., 2016; Helm et al., 2020). These studies show that the timing and amount of triceps-surae muscle-tendon unit pre-activation in DJs are differentially regulated based on the load applied to the muscle, being optimal in normal "Earth" gravity conditions (Avela et al., 1994), but decreased in simulated hypo-gravity, hyper-gravity (Avela et al., 1994; Ritzmann et al., 2016), or unknown conditions (i.e., unknown falling heights; Helm et al., 2020). Some authors indicated that, when falling from heights different from the optimal one [defined as the drop height giving a maximum DJ performance indicated as peak ground reaction force (GRF) or jump high], electromyographic (EMG) activity of the plantar flexors increases from lower than optimal to higher than optimal heights (Ishikawa and Komi, 2004; Sousa et al., 2007). These findings highlight the ability of the central nervous system to regulate the timing and amount of pre-activation according to different jumping conditions, thus regulating muscle fascicle length, tendon and joint stiffness as well as position, in order to safely land on the ground and quickly re-bounce. Similarly, to pre-activation, also in the braking phase, the plantar flexors are differentially regulated. In optimal height (i.e., load) jumping conditions, gastrocnemius medialis (GM) fascicles shorten at early ground contact (possibly due to the intervention of the stretch reflex; Gollhofer et al., 1992) and behave quasi-isometrically in the late braking phase, enabling tendon elongation, and storage of elastic energy (Gollhofer et al., 1992; Fukashiro et al., 2005; Sousa et al., 2007). When increasing the falling height (augmenting the impact GRF), the quasi-isometric behavior of fascicles disappears, and fast fascicle lengthening occurs (Ishikawa et al., 2005; Sousa et al., 2007). In the third and last PO phase, fascicles shorten and the tendon releases the elastic energy previously stored. Bobbert et al. (1987) reported no influence of jumping height on the work done and on the net vertical impulse assessed during PO; this observation suggests that, despite an optimal DJ performance might be achieved only in specific conditions (falling heights, loads), the central nervous system seems to be able to regulate muscle behavior in order to effectively perform the required task also in challenging situations. Although the regulation of triceps-surae muscle-tendon unit in DJs has been extensively investigated, very few studies focused on sarcomeres behavior during the performance of this SSC movement (Kurokawa et al., 2003; Fukashiro et al., 2005, 2006). Sarcomeres represent muscle contractile units and are known to express different amounts of force depending on their length (Gordon et al., 1966; Walker and Schrodt, 1974); thus, understanding the time course of their responses during DJs is fundamental to gain further insights into muscle force-generating capacity. In vivo measurement of sarcomere length in humans has been so far been performed only in static positions and under highly controlled experimental conditions (Llewellyn et al., 2008; Sanchez et al., 2015). Instead, human sarcomere length estimation (achieved by dividing GM measured fascicle length for a fixed sarcomere number) in dynamic contractions provided an indirect measure of sarcomere operating range during squat jump, countermovement jump, and DJ (Fukashiro et al., 2005, 2006; Kurokawa et al., 2003). The results of these studies showed that sarcomeres operate in the ascending limb of their length-tension (L-T) relationship in all types of jumps, and particularly so in DJ. However, most of the available observations on sarcomere and muscle fascicle behavior were made in condition of constant gravity. Thus, in order to understand how sarcomere and muscle fascicle length are regulated in variable gravity conditions, we performed experiments in a parabolic flight, involving variable gravity levels, ranging from about zero-g to about double the Earth's gravity (1 g; Waldvogel et al., 2021). Specifically, the aims of the present study were as follows: 1. To investigate the ability of the neuromuscular system in regulating fascicle length in response to conditions of variable gravity. 2. To estimate sarcomere operative length in the different DJ phases, in order to calculate its theoretical force production and its possible modulation in conditions of variable gravity. We hypothesized that muscle fascicles would be differentially regulated in different gravity conditions compared to 1 g, particularly in anticipation of landing and re-bouncing in unknown gravity levels. In addition, we hypothesized that sarcomeres would operate in the upper part of the ascending limb of their L-T relationship, possibly lengthening during the braking phase (especially in hyper-gravity) while operating quasi-isometrically in 1 g.}, language = {en} } @article{StaeudleSeynnesLapsetal.2021, author = {St{\"a}udle, Benjamin and Seynnes, Olivier and Laps, Guido and G{\"o}ll, Fabian and Br{\"u}ggemann, Gert-Peter and Albracht, Kirsten}, title = {Recovery from achilles tendon repair: a combination of Postsurgery Outcomes and Insufficient remodeling of muscle and tendon}, series = {Medicine \& Science in Sports \& Exercise}, volume = {53}, journal = {Medicine \& Science in Sports \& Exercise}, number = {7}, publisher = {American College of Sports Medicine}, address = {Philadelphia, Pa.}, issn = {1530-0315}, doi = {10.1249/MSS.0000000000002592}, pages = {1356 -- 1366}, year = {2021}, abstract = {Achilles tendon rupture (ATR) patients have persistent functional deficits in the triceps surae muscle-tendon unit (MTU). The complex remodeling of the MTU accompanying these deficits remains poorly understood. The purpose of the present study was to associate in vivo and in silico data to investigate the relations between changes inMTU properties and strength deficits inATR patients. Methods: Elevenmale subjects who had undergone surgical repair of complete unilateral ATR were examined 4.6 ± 2.0 (mean ± SD) yr after rupture. Gastrocnemius medialis (GM) tendon stiffness, morphology, and muscle architecture were determined using ultrasonography. The force-length relation of the plantar flexor muscles was assessed at five ankle joint angles. In addition, simulations (OpenSim) of the GM MTU force-length properties were performed with various iterations of MTU properties found between the unaffected and the affected side. Results: The affected side of the patients displayed a longer, larger, and stiffer GM tendon (13\% ± 10\%, 105\% ± 28\%, and 54\% ± 24\%, respectively) compared with the unaffected side. The GM muscle fascicles of the affected side were shorter (32\% ± 12\%) and with greater pennation angles (31\% ± 26\%). A mean deficit in plantarflexion moment of 31\% ± 10\% was measured. Simulations indicate that pairing an intact muscle with a longer tendon shifts the optimal angular range of peak force outside physiological angular ranges, whereas the shorter muscle fascicles and tendon stiffening seen in the affected side decrease this shift, albeit incompletely. Conclusions: These results suggest that the substantial changes in MTU properties found in ATR patients may partly result from compensatory remodeling, although this process appears insufficient to fully restore muscle function.}, language = {en} } @article{WerkhausenAlbrachtCroninetal.2018, author = {Werkhausen, Amelie and Albracht, Kirsten and Cronin, Neil J and Paulsen, G{\o}ran and Bojsen-M{\o}ller, Jens and Seynnes, Olivier R}, title = {Effect of training-induced changes in achilles tendon stiffness on muscle-tendon behavior during landing}, series = {Frontiers in physiology}, journal = {Frontiers in physiology}, number = {9}, publisher = {Frontiers Research Foundation}, address = {Lausanne}, issn = {1664-042X}, doi = {10.3389/fphys.2018.00794}, pages = {11 Seiten}, year = {2018}, abstract = {During rapid deceleration of the body, tendons buffer part of the elongation of the muscle-tendon unit (MTU), enabling safe energy dissipation via eccentric muscle contraction. Yet, the influence of changes in tendon stiffness within the physiological range upon these lengthening contractions is unknown. This study aimed to examine the effect of training-induced stiffening of the Achilles tendon on triceps surae muscle-tendon behavior during a landing task. Twenty-one male subjects were assigned to either a 10-week resistance-training program consisting of single-leg isometric plantarflexion (n = 11) or to a non-training control group (n = 10). Before and after the training period, plantarflexion force, peak Achilles tendon strain and stiffness were measured during isometric contractions, using a combination of dynamometry, ultrasound and kinematics data. Additionally, testing included a step-landing task, during which joint mechanics and lengths of gastrocnemius and soleus fascicles, Achilles tendon, and MTU were determined using synchronized ultrasound, kinematics and kinetics data collection. After training, plantarflexion strength and Achilles tendon stiffness increased (15 and 18\%, respectively), and tendon strain during landing remained similar. Likewise, lengthening and negative work produced by the gastrocnemius MTU did not change detectably. However, in the training group, gastrocnemius fascicle length was offset (8\%) to a longer length at touch down and, surprisingly, fascicle lengthening and velocity were reduced by 27 and 21\%, respectively. These changes were not observed for soleus fascicles when accounting for variation in task execution between tests. These results indicate that a training-induced increase in tendon stiffness does not noticeably affect the buffering action of the tendon when the MTU is rapidly stretched. Reductions in gastrocnemius fascicle lengthening and lengthening velocity during landing occurred independently from tendon strain. Future studies are required to provide insight into the mechanisms underpinning these observations and their influence on energy dissipation.}, language = {en} } @article{YangKriechbaumerAlbrachtetal.2014, author = {Yang, Peng-Fei and Kriechbaumer, Andreas and Albracht, Kirsten and Sanno, Maximilian and Ganse, Bergita and Koy, Timmo and Shang, Peng and br{\"u}ggemann, Gert-Peter and M{\"u}ller, Lars Peter and Rittweger, J{\"o}rn}, title = {A novel optical approach for assessing in vivo bone segment deformation and its application in muscle-bone relationship studies in humans}, series = {Journal of Orthopaedic Translation}, volume = {2}, journal = {Journal of Orthopaedic Translation}, number = {4}, publisher = {Elsevier}, address = {Singapore}, issn = {2214-0328}, doi = {10.1016/j.jot.2014.07.078}, pages = {238 -- 238}, year = {2014}, language = {en} } @article{AngermannGuenthnerHanssenetal.2022, author = {Angermann, Susanne and G{\"u}nthner, Roman and Hanssen, Henner and Lorenz, Georg and Braunisch, Matthias C. and Steubl, Dominik and Matschkal, Julia and Kemmner, Stephan and Hausinger, Renate and Block, Zenonas and Haller, Bernhard and Heemann, Uwe and Kotliar, Konstantin and Grimmer, Timo and Schmaderer, Christoph}, title = {Cognitive impairment and microvascular function in end-stage renal disease}, series = {International Journal of Methods in Psychiatric Research (MPR)}, volume = {31}, journal = {International Journal of Methods in Psychiatric Research (MPR)}, number = {2}, publisher = {Wiley}, issn = {1049-8931 (Print)}, doi = {10.1002/mpr.1909}, pages = {1 -- 10}, year = {2022}, abstract = {Objective Hemodialysis patients show an approximately threefold higher prevalence of cognitive impairment compared to the age-matched general population. Impaired microcirculatory function is one of the assumed causes. Dynamic retinal vessel analysis is a quantitative method for measuring neurovascular coupling and microvascular endothelial function. We hypothesize that cognitive impairment is associated with altered microcirculation of retinal vessels. Methods 152 chronic hemodialysis patients underwent cognitive testing using the Montreal Cognitive Assessment. Retinal microcirculation was assessed by Dynamic Retinal Vessel Analysis, which carries out an examination recording retinal vessels' reaction to a flicker light stimulus under standardized conditions. Results In unadjusted as well as in adjusted linear regression analyses a significant association between the visuospatial executive function domain score of the Montreal Cognitive Assessment and the maximum arteriolar dilation as response of retinal arterioles to the flicker light stimulation was obtained. Conclusion This is the first study determining retinal microvascular function as surrogate for cerebral microvascular function and cognition in hemodialysis patients. The relationship between impairment in executive function and reduced arteriolar reaction to flicker light stimulation supports the involvement of cerebral small vessel disease as contributing factor for the development of cognitive impairment in this patient population and might be a target for noninvasive disease monitoring and therapeutic intervention.}, language = {en} } @article{KotliarOrtnerConradietal.2022, author = {Kotliar, Konstantin and Ortner, Marion and Conradi, Anna and Hacker, Patricia and Hauser, Christine and G{\"u}nthner, Roman and Moser, Michaela and Muggenthaler, Claudia and Diehl-Schmid, Janine and Priller, Josef and Schmaderer, Christoph and Grimmer, Timo}, title = {Altered retinal cerebral vessel oscillation frequencies in Alzheimer's disease compatible with impaired amyloid clearance}, series = {Neurobiology of Aging}, volume = {120}, journal = {Neurobiology of Aging}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0197-4580}, doi = {10.1016/j.neurobiolaging.2022.08.012}, pages = {117 -- 127}, year = {2022}, abstract = {Retinal vessels are similar to cerebral vessels in their structure and function. Moderately low oscillation frequencies of around 0.1 Hz have been reported as the driving force for paravascular drainage in gray matter in mice and are known as the frequencies of lymphatic vessels in humans. We aimed to elucidate whether retinal vessel oscillations are altered in Alzheimer's disease (AD) at the stage of dementia or mild cognitive impairment (MCI). Seventeen patients with mild-to-moderate dementia due to AD (ADD); 23 patients with MCI due to AD, and 18 cognitively healthy controls (HC) were examined using Dynamic Retinal Vessel Analyzer. Oscillatory temporal changes of retinal vessel diameters were evaluated using mathematical signal analysis. Especially at moderately low frequencies around 0.1 Hz, arterial oscillations in ADD and MCI significantly prevailed over HC oscillations and correlated with disease severity. The pronounced retinal arterial vasomotion at moderately low frequencies in the ADD and MCI groups would be compatible with the view of a compensatory upregulation of paravascular drainage in AD and strengthen the amyloid clearance hypothesis.}, language = {en} } @article{NeumaierWeissVeldemanetal.2021, author = {Neumaier, Felix and Weiss, Miriam and Veldeman, Michael and Kotliar, Konstantin and Wiesmann, Martin and Schulze-Steinen, Henna and H{\"o}llig, Anke and Clusmann, Hans and Schubert, Gerrit Alexander and Albanna, Walid}, title = {Changes in endogenous daytime melatonin levels after aneurysmal subarachnoid hemorrhage - preliminary findings from an observational cohort study}, series = {Clinical Neurology and Neurosurgery}, volume = {208}, journal = {Clinical Neurology and Neurosurgery}, number = {Article No.: 106870}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0303-8467}, doi = {10.1016/j.clineuro.2021.106870}, year = {2021}, abstract = {Aneurysmal subarachnoid hemorrhage (aSAH) is associated with early and delayed brain injury due to several underlying and interrelated processes, which include inflammation, oxidative stress, endothelial, and neuronal apoptosis. Treatment with melatonin, a cytoprotective neurohormone with anti-inflammatory, anti-oxidant and anti-apoptotic effects, has been shown to attenuate early brain injury (EBI) and to prevent delayed cerebral vasospasm in experimental aSAH models. Less is known about the role of endogenous melatonin for aSAH outcome and how its production is altered by the pathophysiological cascades initiated during EBI. In the present observational study, we analyzed changes in melatonin levels during the first three weeks after aSAH.}, language = {en} } @article{AlnemerKotliarNeuhausetal.2023, author = {Alnemer, Momin Sami Mohammad and Kotliar, Konstantin and Neuhaus, Valentin and Pape, Hans-Christoph and Ciritsis, Bernhard D.}, title = {Cost-effectiveness analysis of surgical proximal femur fracture prevention in elderly: a Markov cohort simulation model}, series = {Cost Effectiveness and Resource Allocation}, journal = {Cost Effectiveness and Resource Allocation}, number = {21, Article number: 77}, publisher = {Springer Nature}, issn = {1478-7547}, doi = {10.1186/s12962-023-00482-4}, pages = {12 Seiten}, year = {2023}, abstract = {Background Hip fractures are a common and costly health problem, resulting in significant morbidity and mortality, as well as high costs for healthcare systems, especially for the elderly. Implementing surgical preventive strategies has the potential to improve the quality of life and reduce the burden on healthcare resources, particularly in the long term. However, there are currently limited guidelines for standardizing hip fracture prophylaxis practices. Methods This study used a cost-effectiveness analysis with a finite-state Markov model and cohort simulation to evaluate the primary and secondary surgical prevention of hip fractures in the elderly. Patients aged 60 to 90 years were simulated in two different models (A and B) to assess prevention at different levels. Model A assumed prophylaxis was performed during the fracture operation on the contralateral side, while Model B included individuals with high fracture risk factors. Costs were obtained from the Centers for Medicare \& Medicaid Services, and transition probabilities and health state utilities were derived from available literature. The baseline assumption was a 10\% reduction in fracture risk after prophylaxis. A sensitivity analysis was also conducted to assess the reliability and variability of the results. Results With a 10\% fracture risk reduction, model A costs between \$8,850 and \$46,940 per quality-adjusted life-year (\$/QALY). Additionally, it proved most cost-effective in the age range between 61 and 81 years. The sensitivity analysis established that a reduction of ≥ 2.8\% is needed for prophylaxis to be definitely cost-effective. The cost-effectiveness at the secondary prevention level was most sensitive to the cost of the contralateral side's prophylaxis, the patient's age, and fracture treatment cost. For high-risk patients with no fracture history, the cost-effectiveness of a preventive strategy depends on their risk profile. In the baseline analysis, the incremental cost-effectiveness ratio at the primary prevention level varied between \$11,000/QALY and \$74,000/QALY, which is below the defined willingness to pay threshold. Conclusion Due to the high cost of hip fracture treatment and its increased morbidity, surgical prophylaxis strategies have demonstrated that they can significantly relieve the healthcare system. Various key assumptions facilitated the modeling, allowing for adequate room for uncertainty. Further research is needed to evaluate health-state-associated risks.}, language = {en} } @article{KuchlerGuenthnerRibeiroetal.2023, author = {Kuchler, Timon and G{\"u}nthner, Roman and Ribeiro, Andrea and Hausinger, Renate and Streese, Lukas and W{\"o}hnl, Anna and Kesseler, Veronika and Negele, Johanna and Assali, Tarek and Carbajo-Lozoya, Javier and Lech, Maciej and Adorjan, Kristina and Stubbe, Hans Christian and Hanssen, Henner and Kotliar, Konstantin and Haller, Berhard and Heemann, Uwe and Schmaderer, Christoph}, title = {Persistent endothelial dysfunction in post-COVID-19 syndrome and its associations with symptom severity and chronic inflammation}, volume = {26}, publisher = {Springer Nature}, address = {Dordrecht}, doi = {10.1007/s10456-023-09885-6}, pages = {547 -- 563}, year = {2023}, abstract = {Background Post-COVID-19 syndrome (PCS) is a lingering disease with ongoing symptoms such as fatigue and cognitive impairment resulting in a high impact on the daily life of patients. Understanding the pathophysiology of PCS is a public health priority, as it still poses a diagnostic and treatment challenge for physicians. Methods In this prospective observational cohort study, we analyzed the retinal microcirculation using Retinal Vessel Analysis (RVA) in a cohort of patients with PCS and compared it to an age- and gender-matched healthy cohort (n = 41, matched out of n = 204). Measurements and main results PCS patients exhibit persistent endothelial dysfunction (ED), as indicated by significantly lower venular flicker-induced dilation (vFID; 3.42\% ± 1.77\% vs. 4.64\% ± 2.59\%; p = 0.02), narrower central retinal artery equivalent (CRAE; 178.1 [167.5-190.2] vs. 189.1 [179.4-197.2], p = 0.01) and lower arteriolar-venular ratio (AVR; (0.84 [0.8-0.9] vs. 0.88 [0.8-0.9], p = 0.007). When combining AVR and vFID, predicted scores reached good ability to discriminate groups (area under the curve: 0.75). Higher PCS severity scores correlated with lower AVR (R = - 0.37 p = 0.017). The association of microvascular changes with PCS severity were amplified in PCS patients exhibiting higher levels of inflammatory parameters. Conclusion Our results demonstrate that prolonged endothelial dysfunction is a hallmark of PCS, and impairments of the microcirculation seem to explain ongoing symptoms in patients. As potential therapies for PCS emerge, RVA parameters may become relevant as clinical biomarkers for diagnosis and therapy management.}, language = {en} } @article{KuertenKotliarFuestetal.2021, author = {Kuerten, David and Kotliar, Konstantin and Fuest, Matthias and Walter, Peter and Hollstein, Muriel and Plange, Niklas}, title = {Does hemispheric vascular regulation differ significantly in glaucoma patients with altitudinal visual field asymmetry? A single-center, prospective study}, series = {International Ophthalmology}, volume = {41}, journal = {International Ophthalmology}, number = {41}, editor = {Neri, Piergiorgio}, publisher = {Springer}, address = {Berlin}, isbn = {1573-2630}, doi = {10.1007/s10792-021-01876-0}, pages = {3109 -- 3119}, year = {2021}, abstract = {Purpose Vascular risk factors and ocular perfusion are heatedly discussed in the pathogenesis of glaucoma. The retinal vessel analyzer (RVA, IMEDOS Systems, Germany) allows noninvasive measurement of retinal vessel regulation. Significant differences especially in the veins between healthy subjects and patients suffering from glaucoma were previously reported. In this pilot-study we investigated if localized vascular regulation is altered in glaucoma patients with altitudinal visual field defect asymmetry. Methods 15 eyes of 12 glaucoma patients with advanced altitudinal visual field defect asymmetry were included. The mean defect was calculated for each hemisphere separately (-20.99 ± 10.49 pro- found hemispheric visual field defect vs -7.36 ± 3.97 dB less profound hemisphere). After pupil dilation, RVA measurements of retinal arteries and veins were conducted using the standard protocol. The superior and inferior retinal vessel reactivity were measured consecutively in each eye. Results Significant differences were recorded in venous vessel constriction after flicker light stimulation and overall amplitude of the reaction (p \ 0.04 and p \ 0.02 respectively) in-between the hemispheres spheres. Vessel reaction was higher in the hemisphere corresponding to the more advanced visual field defect. Arterial diameters reacted similarly, failing to reach statistical significance. Conclusion Localized retinal vessel regulation is significantly altered in glaucoma patients with asymmetri altitudinal visual field defects. Veins supplying the hemisphere concordant to a less profound visual field defect show diminished diameter changes. Vascular dysregulation might be particularly important in early glaucoma stages prior to a significant visual field defect.}, language = {en} } @article{AlbannaConzenWeissetal.2021, author = {Albanna, Walid and Conzen, Catharina and Weiss, Miriam and Seyfried, Katharina and Kotliar, Konstantin and Schmidt, Tobias Philip and Kuerten, David and Hescheler, J{\"u}rgen and Bruecken, Anne and Schmidt-Trucks{\"a}ss, Arno and Neumaier, Felix and Wiesmann, Martin and Clusmann, Hans and Schubert, Gerrit Alexander}, title = {Non-invasive assessment of neurovascular coupling after aneurysmal subarachnoid hemorrhage: a prospective observational trial using retinal vessel analysis}, series = {Frontiers in Neurology}, volume = {12}, journal = {Frontiers in Neurology}, number = {12}, issn = {1664-2295}, doi = {10.3389/fneur.2021.690183}, pages = {1 -- 15}, year = {2021}, abstract = {Delayed cerebral ischemia (DCI) is a common complication after aneurysmal subarachnoid hemorrhage (aSAH) and can lead to infarction and poor clinical outcome. The underlying mechanisms are still incompletely understood, but animal models indicate that vasoactive metabolites and inflammatory cytokines produced within the subarachnoid space may progressively impair and partially invert neurovascular coupling (NVC) in the brain. Because cerebral and retinal microvasculature are governed by comparable regulatory mechanisms and may be connected by perivascular pathways, retinal vascular changes are increasingly recognized as a potential surrogate for altered NVC in the brain. Here, we used non-invasive retinal vessel analysis (RVA) to assess microvascular function in aSAH patients at different times after the ictus.}, language = {en} } @article{WerfelGuenthnerHapfelmeieretal.2022, author = {Werfel, Stanislas and G{\"u}nthner, Roman and Hapfelmeier, Alexander and Hanssen, Henner and Kotliar, Konstantin and Heemann, Uwe and Schmaderer, Christoph}, title = {Identification of cardiovascular high-risk groups from dynamic retinal vessel signals using untargeted machine learning}, series = {Cardiovascular Research}, volume = {118}, journal = {Cardiovascular Research}, number = {2}, editor = {Guzik, Tomasz J.}, publisher = {Oxford University Press}, address = {Oxford}, issn = {0008-6363}, doi = {10.1093/cvr/cvab040}, pages = {612 -- 621}, year = {2022}, abstract = {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.}, language = {en} } @article{MalanHamerKaeneletal.2020, author = {Malan, Leone and Hamer, Mark and K{\"a}nel, Roland von and Kotliar, Konstantin and Wyk, Roelof D. van and Lambert, Gavin W. and Vilser, Walthard and Ziemssen, Tjalf and Schlaich, Markus P. and Smith, Wayne and Magnusson, Martin and Wentzel, Annemarie and Myburgh, Carlien E. and Steyn, Hendrik S. and Malan, Nico T.}, title = {Delayed retinal vein recovery responses indicate both non-adaptation to stress as well as increased risk for stroke: the SABPA study}, series = {Cardiovascular Journal of Africa}, volume = {26}, journal = {Cardiovascular Journal of Africa}, number = {31}, publisher = {Clinics Cardive Publishing}, address = {Durbanville}, issn = {1680-0745}, doi = {10.5830/CVJA-2020-031}, pages = {1 -- 12}, year = {2020}, language = {en} } @article{StreeseKotliarDeiserothetal.2020, author = {Streese, Lukas and Kotliar, Konstantin and Deiseroth, Arne and Infanger, Denis and Gugleta, Konstantin and Schmaderer, Christoph and Hanssen, Henner}, title = {Retinal endothelial function in cardiovascular risk patients: A randomized controlled exercise trial}, series = {Scandinavian Journal of Medicine and Science in Sports}, volume = {30}, journal = {Scandinavian Journal of Medicine and Science in Sports}, number = {2}, publisher = {Wiley}, address = {Oxford}, issn = {1600-0838}, doi = {10.1111/sms.13560}, pages = {272 -- 280}, year = {2020}, abstract = {The aim of this study was to investigate, for the first time, the effects of high-intensity interval training (HIIT) on retinal microvascular endothelial function in cardiovascular (CV) risk patients. In the randomized controlled trial, middle-aged and previously sedentary patients with increased CV risk (aged 58 ± 6 years) with ≥ two CV risk factors were randomized into a 12-week HIIT (n = 33) or control group (CG, n = 36) with standard physical activity recommendations. A blinded examiner measured retinal endothelial function by flicker light-induced maximal arteriolar (ADmax) and venular (VDmax) dilatation as well as the area under the arteriolar (AFarea) and venular (VFarea) flicker curve using a retinal vessel analyzer. Standardized assessments of CV risk factors, cardiorespiratory fitness, and retinal endothelial function were performed before and after HIIT. HIIT reduced body mass index, fat mass, and low-density lipoprotein and increased muscle mass and peak oxygen uptake (VO2peak). Both ADmax (pre: 2.7 ± 2.1\%, post: 3.0 ± 2.2\%, P = .018) and AFarea (pre: 32.6 ± 28.4\%*s, post: 37.7 ± 30.6\%*s, P = .016) increased after HIIT compared with CG (ADmax, pre: 3.2 ± 1.8\%, post: 2.9 ± 1.8\%, P = .254; AFarea, pre: 41.6 ± 28.5\%*s, post: 37.8 ± 27.0\%*s, P = .186). Venular function remained unchanged after HIIT. There was a significant association between ∆-change VO2peak and ∆-changes ADmax and AFarea (P = .026, R² = 0.073; P = .019, R² = 0.081, respectively). 12-weeks of HIIT improved retinal endothelial function in middle-aged patients with increased CV risk independent of the reduction in classical CV risk factors. Exercise has the potential to reverse or at least postpone progression of small vessel disease in older adults with increased CV risk under standard medication. Dynamic retinal vessel analysis seems to be a sensitive tool to detect treatment effects of exercise interventions on retinal microvascular endothelial function in middle-aged individuals with increased CV risk.}, language = {en} } @article{HamouKotliarTanetal.2020, author = {Hamou, Hussam Aldin and Kotliar, Konstantin and Tan, Sonny Kian and Weiß, Christel and Blume, Christian and Clusmann, Hans and Schubert, Gerrit Alexander and Albanna, Walid}, title = {Surgical nuances and placement of subgaleal drains for supratentorial procedures—a prospective analysis of efficacy and outcome in 150 craniotomies}, series = {Acta Neurochirurgica}, volume = {2020}, journal = {Acta Neurochirurgica}, number = {162}, publisher = {Springer Nature}, address = {Cham}, issn = {0942-0940}, doi = {10.1007/s00701-019-04196-6}, pages = {729 -- 736}, year = {2020}, abstract = {Background For supratentorial craniotomy, surgical access, and closure technique, including placement of subgaleal drains, may vary considerably. The influence of surgical nuances on postoperative complications such as cerebrospinal fluid leakage or impaired wound healing overall remains largely unclear. With this study, we are reporting our experiences and the impact of our clinical routines on outcome in a prospectively collected data set. Method We prospectively observed 150 consecutive patients undergoing supratentorial craniotomy and recorded technical variables (type/length of incision, size of craniotomy, technique of dural and skin closure, type of dressing, and placement of subgaleal drains). Outcome variables (subgaleal hematoma/CSF collection, periorbital edema, impairment of wound healing, infection, and need for operative revision) were recorded at time of discharge and at late follow-up. Results Early subgaleal fluid collection was observed in 36.7\% (2.8\% at the late follow-up), and impaired wound healing was recorded in 3.3\% of all cases, with an overall need for operative revision of 6.7\%. Neither usage of dural sealants, lack of watertight dural closure, and presence of subgaleal drains, nor type of skin closure or dressing influenced outcome. Curved incisions, larger craniotomy, and tumor size, however, were associated with an increase in early CSF or hematoma collection (p < 0.0001, p = 0.001, p < 0.01 resp.), and larger craniotomy size was associated with longer persistence of subgaleal fluid collections (p < 0.05). Conclusions Based on our setting, individual surgical nuances such as the type of dural closure and the use of subgaleal drains resulted in a comparable complication rate and outcome. Subgaleal fluid collections were frequently observed after supratentorial procedures, irrespective of the closing technique employed, and resolve spontaneously in the majority of cases without significant sequelae. Our results are limited due to the observational nature in our single-center study and need to be validated by supportive prospective randomized design.}, language = {en} } @article{RamoshabaHuismanLammertynetal.2020, author = {Ramoshaba, Nthai E. and Huisman, Hugo W. and Lammertyn, Leandi and Kotliar, Konstantin and Schutte, Aletta E. and Smith, Wayne}, title = {Retinal microvasculature and masked hypertension in young adults: the African-PREDICT study}, series = {Hypertension Research}, journal = {Hypertension Research}, number = {43}, publisher = {Springer Nature}, address = {Osaka}, issn = {1348-4214}, doi = {10.1038/s41440-020-0487-0}, pages = {1231 -- 1238}, year = {2020}, abstract = {Masked hypertension is known to induce microvascular complications. However, it is unclear whether early microvascular changes are already occurring in young, otherwise healthy adults. We therefore investigated whether retinal microvascular calibers and acute responses to a flicker stimulus are related to masked hypertension. We used the baseline data of 889 participants aged 20-30 years who were taking part in the African Prospective study on the Early Detection and Identification of Cardiovascular Disease and Hypertension. Clinic and 24-h ambulatory blood pressure were measured. The central retinal artery equivalent (CRAE) and central retinal vein equivalent were calculated from fundus images, and retinal vessel dilation was determined in response to flicker light-induced provocation. A smaller CRAE was observed in those with masked hypertension vs. those with normotension (157.1 vs. 161.2 measuring units, P < 0.001). In forward multivariable-adjusted regression analysis, only CRAE was negatively related to masked hypertension [adjusted R² = 0.267, β = -0.097 (95\% CI = -0.165; -0.029), P = 0.005], but other retinal microvascular parameters were not associated with masked hypertension. In multivariable logistic regression analyses, masked hypertension [OR = 2.333, (95\% CI = 1.316; 4.241), P = 0.004] was associated with a narrower CRAE. In young healthy adults, masked hypertension was associated with retinal arteriolar narrowing, thereby reflecting early microvascular alterations known to predict cardiovascular outcomes in later life.}, language = {en} } @article{NeumaierKotliarHaerenetal.2021, author = {Neumaier, Felix and Kotliar, Konstantin and Haeren, Roel Hubert Louis and Temel, Yasin and L{\"u}ke, Jan Niklas and Seyam, Osama and Lindauer, Ute and Clusmann, Hans and Hescheler, J{\"u}rgen and Schubert, Gerrit Alexander and Schneider, Toni and Albanna, Walid}, title = {Retinal Vessel Responses to Flicker Stimulation Are Impaired in Ca v 2.3-Deficient Mice—An in- vivo Evaluation Using Retinal Vessel Analysis (RVA)}, series = {Frontiers in Neurology}, volume = {12}, journal = {Frontiers in Neurology}, publisher = {Frontiers}, doi = {10.3389/fneur.2021.659890}, pages = {1 -- 11}, year = {2021}, language = {en} } @article{MuschallikMolinnusBongaertsetal.2017, author = {Muschallik, Lukas and Molinnus, Denise and Bongaerts, Johannes and Pohl, Martina and Wagner, Torsten and Sch{\"o}ning, Michael Josef and Siegert, Petra and Selmer, Thorsten}, title = {(R,R)-Butane-2,3-diol Dehydrogenase from Bacillus clausii DSM 8716T: Cloning and Expression of the bdhA-Gene, and Initial Characterization of Enzyme}, series = {Journal of Biotechnology}, volume = {258}, journal = {Journal of Biotechnology}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0168-1656}, doi = {10.1016/j.jbiotec.2017.07.020}, pages = {41 -- 50}, year = {2017}, abstract = {The gene encoding a putative (R,R)-butane-2,3-diol dehydrogenase (bdhA) from Bacillus clausii DSM 8716T was isolated, sequenced and expressed in Escherichia coli. The amino acid sequence of the encoded protein is only distantly related to previously studied enzymes (identity 33-43\%) and exhibited some uncharted peculiarities. An N-terminally StrepII-tagged enzyme variant was purified and initially characterized. The isolated enzyme catalyzed the (R)-specific oxidation of (R,R)- and meso-butane-2,3-diol to (R)- and (S)-acetoin with specific activities of 12 U/mg and 23 U/mg, respectively. Likewise, racemic acetoin was reduced with a specific activity of up to 115 U/mg yielding a mixture of (R,R)- and meso-butane-2,3-diol, while the enzyme reduced butane-2,3-dione (Vmax 74 U/mg) solely to (R,R)-butane-2,3-diol via (R)-acetoin. For these reactions only activity with the co-substrates NADH/NAD+ was observed. The enzyme accepted a selection of vicinal diketones, α-hydroxy ketones and vicinal diols as alternative substrates. Although the physiological function of the enzyme in B. clausii remains elusive, the data presented herein clearly demonstrates that the encoded enzyme is a genuine (R,R)-butane-2,3-diol dehydrogenase with potential for applications in biocatalysis and sensor development.}, language = {en} } @article{GeierLehnertzBialonski2015, author = {Geier, Christian and Lehnertz, Klaus and Bialonski, Stephan}, title = {Time-dependent degree-degree correlations in epileptic brain networks: from assortative to dissortative mixing}, series = {Frontiers in Human Neuroscience}, journal = {Frontiers in Human Neuroscience}, publisher = {Frontiers Research Foundation}, address = {Lausanne}, issn = {1662-5161}, doi = {10.3389/fnhum.2015.00462}, year = {2015}, language = {en} } @article{UysalCreutzFiratetal.2022, author = {Uysal, Karya and Creutz, Till and Firat, Ipek Seda and Artmann, Gerhard and Teusch, Nicole and Temiz Artmann, Ayseg{\"u}l}, title = {Bio-functionalized ultra-thin, large-area and waterproof silicone membranes for biomechanical cellular loading and compliance experiments}, series = {Polymers}, volume = {14}, journal = {Polymers}, number = {11}, publisher = {MDPI}, address = {Basel}, issn = {2073-4360}, pages = {2213}, year = {2022}, abstract = {Biocompatibility, flexibility and durability make polydimethylsiloxane (PDMS) membranes top candidates in biomedical applications. CellDrum technology uses large area, <10 µm thin membranes as mechanical stress sensors of thin cell layers. For this to be successful, the properties (thickness, temperature, dust, wrinkles, etc.) must be precisely controlled. The following parameters of membrane fabrication by means of the Floating-on-Water (FoW) method were investigated: (1) PDMS volume, (2) ambient temperature, (3) membrane deflection and (4) membrane mechanical compliance. Significant differences were found between all PDMS volumes and thicknesses tested (p < 0.01). They also differed from the calculated values. At room temperatures between 22 and 26 °C, significant differences in average thickness values were found, as well as a continuous decrease in thicknesses within a 4 °C temperature elevation. No correlation was found between the membrane thickness groups (between 3-4 µm) in terms of deflection and compliance. We successfully present a fabrication method for thin bio-functionalized membranes in conjunction with a four-step quality management system. The results highlight the importance of tight regulation of production parameters through quality control. The use of membranes described here could also become the basis for material testing on thin, viscous layers such as polymers, dyes and adhesives, which goes far beyond biological applications.}, language = {en} } @article{TemizArtmannKurulgandemirciFıratetal.2021, author = {Temiz Artmann, Ayseg{\"u}l and Kurulgan demirci, Eylem and F{\i}rat, Ipek Seda and Oflaz, Hakan and Artmann, Gerhard}, title = {Recombinant activated protein C (rhAPC) affects lipopolysaccharide-induced mechanical compliance changes and beat frequency of mESC-derived cardiomyocyte monolayers}, series = {SHOCK}, journal = {SHOCK}, publisher = {Wolters Kluwer}, address = {K{\"o}ln}, issn = {1540-0514}, doi = {10.1097/SHK.0000000000001845}, year = {2021}, language = {en} } @article{BialonskiCaronSchloenetal.2016, author = {Bialonski, Stephan and Caron, David A. and Schloen, Julia and Feudel, Ulrike and Kantz, Holger and Moorthi, Stefanie D.}, title = {Phytoplankton dynamics in the Southern California Bight indicate a complex mixture of transport and biology}, series = {Journal of Plankton Research}, volume = {38}, journal = {Journal of Plankton Research}, number = {4}, publisher = {Oxford University Press}, address = {Oxford}, issn = {1464-3774}, doi = {10.1093/plankt/fbv122}, pages = {1077 -- 1091}, year = {2016}, abstract = {The stimulation and dominance of potentially harmful phytoplankton taxa at a given locale and time are determined by local environmental conditions as well as by transport to or from neighboring regions. The present study investigated the occurrence of common harmful algal bloom (HAB) taxa within the Southern California Bight, using cross-correlation functions to determine potential dependencies between HAB taxa and environmental factors, and potential links to algal transport via local hydrography and currents. A simulation study, in which Lagrangian particles were released, was used to assess travel times due to advection by prevailing ocean currents in the bight. Our results indicate that transport of some taxa may be an important mechanism for the expansion of their distributions into other regions, which was supported by mean travel times derived from our simulation study and other literature on ocean currents in the Southern California Bight. In other cases, however, phytoplankton dynamics were rather linked to local environmental conditions, including coastal upwelling events. Overall, our study shows that complex current patterns in the Southern California Bight may contribute significantly to the formation and expansion of HABs in addition to local environmental factors determining the spatiotemporal dynamics of phytoplankton blooms.}, language = {en} } @article{Gaigall2023, author = {Gaigall, Daniel}, title = {Allocating and forecasting changes in risk}, series = {Journal of risk}, volume = {25}, journal = {Journal of risk}, number = {3}, editor = {AitSahlia, Farid}, publisher = {Infopro Digital Risk}, address = {London}, issn = {1755-2842}, doi = {10.21314/JOR.2022.048}, pages = {1 -- 24}, year = {2023}, abstract = {We consider time-dependent portfolios and discuss the allocation of changes in the risk of a portfolio to changes in the portfolio's components. For this purpose we adopt established allocation principles. We also use our approach to obtain forecasts for changes in the risk of the portfolio's components. To put the approach into practice we present an implementation based on the output of a simulation. Allocation is illustrated with an example portfolio in the context of Solvency II. The quality of the forecasts is investigated with an empirical study.}, language = {en} } @article{Gaigall2023, author = {Gaigall, Daniel}, title = {On the applicability of several tests to models with not identically distributed random effects}, series = {Statistics : A Journal of Theoretical and Applied Statistics}, volume = {57}, journal = {Statistics : A Journal of Theoretical and Applied Statistics}, publisher = {Taylor \& Francis}, address = {London}, isbn = {0323-3944}, issn = {1029-4910}, doi = {10.1080/02331888.2023.2193748}, pages = {14 Seiten}, year = {2023}, abstract = {We consider Kolmogorov-Smirnov and Cram{\´e}r-von-Mises type tests for testing central symmetry, exchangeability, and independence. In the standard case, the tests are intended for the application to independent and identically distributed data with unknown distribution. The tests are available for multivariate data and bootstrap procedures are suitable to obtain critical values. We discuss the applicability of the tests to random effects models, where the random effects are independent but not necessarily identically distributed and with possibly unknown distributions. Theoretical results show the adequacy of the tests in this situation. The quality of the tests in models with random effects is investigated by simulations. Empirical results obtained confirm the theoretical findings. A real data example illustrates the application.}, language = {en} } @article{GaigallGerstenberg2023, author = {Gaigall, Daniel and Gerstenberg, Julian}, title = {Cram{\´e}r-von-Mises tests for the distribution of the excess over a confidence level}, series = {Journal of Nonparametric Statistics}, journal = {Journal of Nonparametric Statistics}, publisher = {Taylor \& Francis}, issn = {1048-5252 (Print)}, doi = {10.1080/10485252.2023.2173958}, year = {2023}, abstract = {The Cram{\´e}r-von-Mises distance is applied to the distribution of the excess over a confidence level. Asymptotics of related statistics are investigated, and it is seen that the obtained limit distributions differ from the classical ones. For that reason, quantiles of the new limit distributions are given and new bootstrap techniques for approximation purposes are introduced and justified. The results motivate new one-sample goodness-of-fit tests for the distribution of the excess over a confidence level and a new confidence interval for the related fitting error. Simulation studies investigate size and power of the tests as well as coverage probabilities of the confidence interval in the finite sample case. A practice-oriented application of the Cram{\´e}r-von-Mises tests is the determination of an appropriate confidence level for the fitting approach. The adoption of the idea to the well-known problem of threshold detection in the context of peaks over threshold modelling is sketched and illustrated by data examples.}, language = {en} } @article{LiphardtFernandezGonzaloAlbrachtetal.2023, author = {Liphardt, Anna-Maria and Fernandez-Gonzalo, Rodrigo and Albracht, Kirsten and Rittweger, J{\"o}rn and Vico, Laurence}, title = {Musculoskeletal research in human space flight - unmet needs for the success of crewed deep space exploration}, series = {npj Microgravity}, volume = {9}, journal = {npj Microgravity}, number = {Article number: 9}, publisher = {Springer Nature}, issn = {2373-8065}, doi = {10.1038/s41526-023-00258-3}, pages = {1 -- 9}, year = {2023}, abstract = {Based on the European Space Agency (ESA) Science in Space Environment (SciSpacE) community White Paper "Human Physiology - Musculoskeletal system", this perspective highlights unmet needs and suggests new avenues for future studies in musculoskeletal research to enable crewed exploration missions. The musculoskeletal system is essential for sustaining physical function and energy metabolism, and the maintenance of health during exploration missions, and consequently mission success, will be tightly linked to musculoskeletal function. Data collection from current space missions from pre-, during-, and post-flight periods would provide important information to understand and ultimately offset musculoskeletal alterations during long-term spaceflight. In addition, understanding the kinetics of the different components of the musculoskeletal system in parallel with a detailed description of the molecular mechanisms driving these alterations appears to be the best approach to address potential musculoskeletal problems that future exploratory-mission crew will face. These research efforts should be accompanied by technical advances in molecular and phenotypic monitoring tools to provide in-flight real-time feedback.}, language = {en} } @article{BayerTemizArtmannDigeletal.2020, author = {Bayer, Robin and Temiz Artmann, Ayseg{\"u}l and Digel, Ilya and Falkenstein, Julia and Artmann, Gerhard and Creutz, Till and Hescheler, J{\"u}rgen}, title = {Mechano-pharmacological testing of L-Type Ca²⁺ channel modulators via human vascular celldrum model}, series = {Cellular Physiology and Biochemistry}, volume = {54}, journal = {Cellular Physiology and Biochemistry}, publisher = {Cell Physiol Biochem Press}, address = {D{\"u}sseldorf}, issn = {1421-9778}, doi = {10.33594/000000225}, pages = {371 -- 383}, year = {2020}, abstract = {Background/Aims: This study aimed to establish a precise and well-defined working model, assessing pharmaceutical effects on vascular smooth muscle cell monolayer in-vitro. It describes various analysis techniques to determine the most suitable to measure the biomechanical impact of vasoactive agents by using CellDrum technology. Methods: The so-called CellDrum technology was applied to analyse the biomechanical properties of confluent human aorta muscle cells (haSMC) in monolayer. The cell generated tensions deviations in the range of a few N/m² are evaluated by the CellDrum technology. This study focuses on the dilative and contractive effects of L-type Ca²⁺ channel agonists and antagonists, respectively. We analyzed the effects of Bay K8644, nifedipine and verapamil. Three different measurement modes were developed and applied to determine the most appropriate analysis technique for the study purpose. These three operation modes are called, particular time mode" (PTM), "long term mode" (LTM) and "real-time mode" (RTM). Results: It was possible to quantify the biomechanical response of haSMCs to the addition of vasoactive agents using CellDrum technology. Due to the supplementation of 100nM Bay K8644, the tension increased approximately 10.6\% from initial tension maximum, whereas, the treatment with nifedipine and verapamil caused a significant decrease in cellular tension: 10nM nifedipine decreased the biomechanical stress around 6,5\% and 50nM verapamil by 2,8\%, compared to the initial tension maximum. Additionally, all tested measurement modes provide similar results while focusing on different analysis parameters. Conclusion: The CellDrum technology allows highly sensitive biomechanical stress measurements of cultured haSMC monolayers. The mechanical stress responses evoked by the application of vasoactive calcium channel modulators were quantified functionally (N/m²). All tested operation modes resulted in equal findings, whereas each mode features operation-related data analysis.}, language = {en} } @article{KaulenSchwabedalSchneideretal.2022, author = {Kaulen, Lars and Schwabedal, Justus T. C. and Schneider, Jules and Ritter, Philipp and Bialonski, Stephan}, title = {Advanced sleep spindle identification with neural networks}, series = {Scientific Reports}, volume = {12}, journal = {Scientific Reports}, number = {Article number: 7686}, publisher = {Springer Nature}, address = {London}, issn = {2045-2322}, doi = {10.1038/s41598-022-11210-y}, pages = {1 -- 10}, year = {2022}, abstract = {Sleep spindles are neurophysiological phenomena that appear to be linked to memory formation and other functions of the central nervous system, and that can be observed in electroencephalographic recordings (EEG) during sleep. Manually identified spindle annotations in EEG recordings suffer from substantial intra- and inter-rater variability, even if raters have been highly trained, which reduces the reliability of spindle measures as a research and diagnostic tool. The Massive Online Data Annotation (MODA) project has recently addressed this problem by forming a consensus from multiple such rating experts, thus providing a corpus of spindle annotations of enhanced quality. Based on this dataset, we present a U-Net-type deep neural network model to automatically detect sleep spindles. Our model's performance exceeds that of the state-of-the-art detector and of most experts in the MODA dataset. We observed improved detection accuracy in subjects of all ages, including older individuals whose spindles are particularly challenging to detect reliably. Our results underline the potential of automated methods to do repetitive cumbersome tasks with super-human performance.}, language = {en} } @article{DigelTemizArtmannNishikawaetal.2004, author = {Digel, Ilya and Temiz Artmann, Ayseg{\"u}l and Nishikawa, K. and Artmann, Gerhard}, title = {Cluster air-ion effects on bacteria and moulds}, series = {Biomedizinische Technik. 49 (2004), H. Erg.-Bd. 2}, journal = {Biomedizinische Technik. 49 (2004), H. Erg.-Bd. 2}, isbn = {0932-4666}, pages = {1040 -- 1041}, year = {2004}, language = {en} } @article{DigelTemizArtmannNishikawaetal.2005, author = {Digel, Ilya and Temiz Artmann, Ayseg{\"u}l and Nishikawa, K. and Cook, M.}, title = {Bactericidal effects of plasma-generated cluster ions}, series = {Medical and Biological Engineering and Computing. 43 (2005), H. 6}, journal = {Medical and Biological Engineering and Computing. 43 (2005), H. 6}, isbn = {1741-0444}, pages = {800 -- 807}, year = {2005}, language = {en} } @article{DigelKernGeenenetal.2020, author = {Digel, Ilya and Kern, Inna and Geenen, Eva-Maria and Akimbekov, Nuraly S.}, title = {Dental plaque removal by ultrasonic toothbrushes}, series = {dentistry journal}, volume = {8}, journal = {dentistry journal}, number = {28}, publisher = {MDPI}, address = {Basel}, issn = {2304-6767}, doi = {10.3390/dj8010028}, pages = {1 -- 13}, year = {2020}, abstract = {With the variety of toothbrushes on the market, the question arises, which toothbrush is best suited to maintain oral health? This thematic review focuses first on plaque formation mechanisms and then on the plaque removal effectiveness of ultrasonic toothbrushes and their potential in preventing oral diseases like periodontitis, gingivitis, and caries. We overviewed the physical effects that occurred during brushing and tried to address the question of whether ultrasonic toothbrushes effectively reduced the microbial burden by increasing the hydrodynamic forces. The results of published studies show that electric toothbrushes, which combine ultrasonic and sonic (or acoustic and mechanic) actions, may have the most promising effect on good oral health. Existing ultrasonic/sonic toothbrush models do not significantly differ regarding the removal of dental biofilm and the reduction of gingival inflammation compared with other electrically powered toothbrushes, whereas the manual toothbrushes show a lower effectiveness.}, language = {en} } @article{DigelAkimbekovTuralievaetal.2013, author = {Digel, Ilya and Akimbekov, Nuraly S. and Turalieva, M. and Mansurov, Z. and Temiz Artmann, Ayseg{\"u}l and Eshibaev, A. and Zhubanova, A.}, title = {Usage of Carbonized Plant Wastes for Purification of Aqueous Solutions}, series = {Journal of Industrial Technology and Engineering}, volume = {2}, journal = {Journal of Industrial Technology and Engineering}, number = {07}, pages = {47 -- 54}, year = {2013}, language = {en} } @article{DigelKayserArtmann2008, author = {Digel, Ilya and Kayser, Peter and Artmann, Gerhard}, title = {Molecular processes in biological thermosensation}, series = {Journal of Biophysics. 2008 (2008)}, journal = {Journal of Biophysics. 2008 (2008)}, isbn = {1687-8000}, pages = {1 -- 9}, year = {2008}, language = {en} } @article{AlexyukBogoyavlenskiyAlexyuketal.2021, author = {Alexyuk, Madina and Bogoyavlenskiy, Andrey and Alexyuk, Pavel and Moldakhanov, Yergali and Berezin, Vladimir and Digel, Ilya}, title = {Epipelagic microbiome of the Small Aral Sea: Metagenomic structure and ecological diversity}, series = {MicrobiologyOpen}, volume = {10}, journal = {MicrobiologyOpen}, number = {1}, publisher = {Wiley}, address = {Weinheim}, issn = {2045-8827}, doi = {10.1002/mbo3.1142}, pages = {1 -- 10}, year = {2021}, abstract = {Microbial diversity studies regarding the aquatic communities that experienced or are experiencing environmental problems are essential for the comprehension of the remediation dynamics. In this pilot study, we present data on the phylogenetic and ecological structure of microorganisms from epipelagic water samples collected in the Small Aral Sea (SAS). The raw data were generated by massive parallel sequencing using the shotgun approach. As expected, most of the identified DNA sequences belonged to Terrabacteria and Actinobacteria (40\% and 37\% of the total reads, respectively). The occurrence of Deinococcus-Thermus, Armatimonadetes, Chloroflexi in the epipelagic SAS waters was less anticipated. Surprising was also the detection of sequences, which are characteristic for strict anaerobes—Ignavibacteria, hydrogen-oxidizing bacteria, and archaeal methanogenic species. We suppose that the observed very broad range of phylogenetic and ecological features displayed by the SAS reads demonstrates a more intensive mixing of water masses originating from diverse ecological niches of the Aral-Syr Darya River basin than presumed before.}, language = {en} } @article{AkimbekovMansurovJandosovetal.2013, author = {Akimbekov, Nuraly S. and Mansurov, Zulkhair and Jandosov, J. and Digel, Ilya and Gossmann, Matthias and Artmann, Gerhard and Temiz Artmann, Ayseg{\"u}l and Zhubanova, Azhar A.}, title = {Wound healing activity of carbonized rice husk}, publisher = {Trans Tech Publications, Switzerland}, address = {B{\"a}ch}, year = {2013}, abstract = {The carbonized rice husk (CRH) was evaluated for its wound healing activity in rats using excision models. In this study, the influences of CRH on wound healing in rat skin in vivo and cellular behavior of human dermal fibroblasts in vitro were investigated. The obtained results showed that the CRH treatment promoted wound epithelization in rats and exhibited moderate inhibition of cell proliferation in vitro. CRH with lanolin oil treated wounds were found to epithelize faster as compared to controls.}, subject = {Wundheilung}, language = {en} } @article{ZhubanovaAknazarovMansurovetal.2010, author = {Zhubanova, Azhar A. and Aknazarov, S. K. and Mansurov, Zulkhair and Digel, Ilya and Kozhalakova, A. A. and Akimbekov, Nuraly S. and O'Heras, Carlos and Tazhibayeva, S. and Artmann, Gerhard and Temiz Artmann, Ayseg{\"u}l}, title = {Adsorption of bacterial Lipopolysaccharides and blood plasma proteins on modified carbonized materials}, year = {2010}, abstract = {Bacterial lipopolysaccharides (endotoxins) show strong biological effects at very low concentrations in human beings and many animals when entering the blood stream. These include affecting structure and function of organs and cells, changing metabolic functions, raising body temperature, triggering the coagulation cascade, modifying hemodynamics and causing septic shock. Because of this toxicity, the removal of even minute amounts is essential for safe parenteral administration of drugs and also for septic shock patients' care. The absence of a general method for endotoxin removal from liquid interfaces urgently requires finding new methods and materials to overcome this gap. Nanostructured carbonized plant parts is a promising material that showed good adsorption properties due to its vast pore network and high surface area. The aim of this study was comparative measurement of endotoxin- and blood proteins-related adsorption rate and adsorption capacity for different carboneous materials produced at different temperatures and under different surface modifications. As a main surface modificator, positively cbarged polymer, polyethileneimine (PEl) was used. Activated carbon materials showed good adsorption properties for LPS and some proteins used in the experiments. During the batch experiments, several techniques (dust removal, autoclaving) were used and optimized for improving the material's adsorption behavior. Also, with the results obtained it was possible to differentiate the materials according to their adsorption capacity and kinetic characteristics. Modification of the surface apparently has not affected hemoglobin binding to the adsorbent's surface. Obtained adsorption isotherms can be used as a powerful tool for designing of future column-based setups for blood purification from LPS, which is especially important for septic shock treatment.}, subject = {Kohlenstofffaser}, language = {en} } @article{StadlerGarveyBocahutetal.2012, author = {Stadler, Andreas M. and Garvey, G. J. and Bocahut, A. and Sacquin-Mora, S. and Digel, Ilya and Schneider, G. J. and Natali, F. and Artmann, Gerhard and Zaccai, G.}, title = {Thermal fluctuations of haemoglobin from different species : adaptation to temperature via conformational dynamics}, series = {Journal of the Royal Society Interface}, volume = {9}, journal = {Journal of the Royal Society Interface}, number = {76}, publisher = {The Royal Society}, address = {London}, issn = {1742-5689}, doi = {10.1098/rsif.2012.0364}, pages = {2845 -- 2855}, year = {2012}, abstract = {Thermodynamic stability, configurational motions and internal forces of haemoglobin (Hb) of three endotherms (platypus, Ornithorhynchus anatinus; domestic chicken, Gallus gallus domesticus and human, Homo sapiens) and an ectotherm (salt water crocodile, Crocodylus porosus) were investigated using circular dichroism, incoherent elastic neutron scattering and coarse-grained Brownian dynamics simulations. The experimental results from Hb solutions revealed a direct correlation between protein resilience, melting temperature and average body temperature of the different species on the 0.1 ns time scale. Molecular forces appeared to be adapted to permit conformational fluctuations with a root mean square displacement close to 1.2 {\AA} at the corresponding average body temperature of the endotherms. Strong forces within crocodile Hb maintain the amplitudes of motion within a narrow limit over the entire temperature range in which the animal lives. In fully hydrated powder samples of human and chicken, Hb mean square displacements and effective force constants on the 1 ns time scale showed no differences over the whole temperature range from 10 to 300 K, in contrast to the solution case. A complementary result of the study, therefore, is that one hydration layer is not sufficient to activate all conformational fluctuations of Hb in the pico- to nanosecond time scale which might be relevant for biological function. Coarse-grained Brownian dynamics simulations permitted to explore residue-specific effects. They indicated that temperature sensing of human and chicken Hb occurs mainly at residues lining internal cavities in the β-subunits.}, language = {en} } @article{SavitskayaKistaubayevaDigeletal.2017, author = {Savitskaya, I. S. and Kistaubayeva, A. S. and Digel, Ilya and Shokatayeva, D. H.}, title = {Physicochemical and Antibacterial Properties of Composite Films Based on Bacterial Cellulose and Chitosan for Wound Dressing Materials}, series = {Eurasian Chemico-Technological Journal}, volume = {19}, journal = {Eurasian Chemico-Technological Journal}, number = {3}, issn = {2522-4867}, doi = {10.18321/ectj670}, pages = {255 -- 264}, year = {2017}, language = {en} } @article{MolinnusMuschallikGonzalezetal.2018, author = {Molinnus, Denise and Muschallik, Lukas and Gonzalez, Laura Osorio and Bongaerts, Johannes and Wagner, Torsten and Selmer, Thorsten and Siegert, Petra and Keusgen, Michael and Sch{\"o}ning, Michael Josef}, title = {Development and characterization of a field-effect biosensor for the detection of acetoin}, series = {Biosensors and Bioelectronics}, volume = {115}, journal = {Biosensors and Bioelectronics}, publisher = {Elsevier}, address = {Amsterdam}, doi = {10.1016/j.bios.2018.05.023}, pages = {1 -- 6}, year = {2018}, abstract = {A capacitive electrolyte-insulator-semiconductor (EIS) field-effect biosensor for acetoin detection has been presented for the first time. The EIS sensor consists of a layer structure of Al/p-Si/SiO₂/Ta₂O₅/enzyme acetoin reductase. The enzyme, also referred to as butane-2,3-diol dehydrogenase from B. clausii DSM 8716T, has been recently characterized. The enzyme catalyzes the (R)-specific reduction of racemic acetoin to (R,R)- and meso-butane-2,3-diol, respectively. Two different enzyme immobilization strategies (cross-linking by using glutaraldehyde and adsorption) have been studied. Typical biosensor parameters such as optimal pH working range, sensitivity, hysteresis, linear concentration range and long-term stability have been examined by means of constant-capacitance (ConCap) mode measurements. Furthermore, preliminary experiments have been successfully carried out for the detection of acetoin in diluted white wine samples.}, language = {en} } @article{AkimbekovDigelZhubanova2013, author = {Akimbekov, Nuraly S. and Digel, Ilya and Zhubanova, A. A.}, title = {Investigation the Influence of Carbonized Material Based On Rice Husk on Viability and Migration of Fibroblasts in T3B3 Cell Culture}, series = {KazNU Bulletin. Biology series}, volume = {59}, journal = {KazNU Bulletin. Biology series}, number = {3/1}, issn = {1563-0218}, pages = {20 -- 23}, year = {2013}, language = {en} } @article{ZerlinDigelStadleretal.2007, author = {Zerlin, Kay and Digel, Ilya and Stadler, Andreas M. and B{\"u}ldt, Georg and Zaccai, Guiseppe and Artmann, Gerhard}, title = {Dynamics and interactions of hemoglobin in human red blood cells and concentrated hemoglobin solutions}, series = {Regenerative medicine. 2 (2007), H. 5}, journal = {Regenerative medicine. 2 (2007), H. 5}, isbn = {1746-0751}, pages = {573 -- 573}, year = {2007}, language = {en} } @article{AkimbekovDigelSherelkhanetal.2020, author = {Akimbekov, Nuraly S. and Digel, Ilya and Sherelkhan, Dinara K. and Lutfor, Afzalunnessa B. and Razzaque, Mohammed S.}, title = {Vitamin D and the Host-Gut Microbiome: A Brief Overview}, series = {Acta Histochemica et Cytochemica}, volume = {53}, journal = {Acta Histochemica et Cytochemica}, number = {3}, publisher = {Japan Society of Histochemistry and Cytochemistry}, address = {Osaka}, issn = {1347-5800}, doi = {10.1267/ahc.20011}, pages = {33 -- 42}, year = {2020}, abstract = {There is a growing body of evidence for the effects of vitamin D on intestinal host-microbiome interactions related to gut dysbiosis and bowel inflammation. This brief review highlights the potential links between vitamin D and gut health, emphasizing the role of vitamin D in microbiological and immunological mechanisms of inflammatory bowel diseases. A comprehensive literature search was carried out in PubMed and Google Scholar using combinations of keywords "vitamin D," "intestines," "gut microflora," "bowel inflammation". Only articles published in English and related to the study topic are included in the review. We discuss how vitamin D (a) modulates intestinal microbiome function, (b) controls antimicrobial peptide expression, and (c) has a protective effect on epithelial barriers in the gut mucosa. Vitamin D and its nuclear receptor (VDR) regulate intestinal barrier integrity, and control innate and adaptive immunity in the gut. Metabolites from the gut microbiota may also regulate expression of VDR, while vitamin D may influence the gut microbiota and exert anti-inflammatory and immune-modulating effects. The underlying mechanism of vitamin D in the pathogenesis of bowel diseases is not fully understood, but maintaining an optimal vitamin D status appears to be beneficial for gut health. Future studies will shed light on the molecular mechanisms through which vitamin D and VDR interactions affect intestinal mucosal immunity, pathogen invasion, symbiont colonization, and antimicrobial peptide expression.}, language = {en} } @article{PogorelovaRogachevAkimbekovetal.2024, author = {Pogorelova, Natalia and Rogachev, Evgeniy and Akimbekov, Nuraly S. and Digel, Ilya}, title = {Effect of dehydration method on the micro- and nanomorphological properties of bacterial cellulose produced by Medusomyces gisevii on different substrates}, series = {Journal of materials science}, volume = {2024}, journal = {Journal of materials science}, publisher = {Springer Science + Business Media}, address = {Dordrecht}, issn = {1573-4803 (Online)}, doi = {10.1007/s10853-024-09596-3}, pages = {13 Seiten}, year = {2024}, abstract = {Many important properties of bacterial cellulose (BC), such as moisture absorption capacity, elasticity and tensile strength, largely depend on its structure. This paper presents a study on the effect of the drying method on BC films produced by Medusomyces gisevii using two different procedures: room temperature drying (RT, (24 ± 2 °C, humidity 65 ± 1\%, dried until a constant weight was reached) and freeze-drying (FD, treated at - 75 °C for 48 h). BC was synthesized using one of two different carbon sources—either glucose or sucrose. Structural differences in the obtained BC films were evaluated using atomic force microscopy (AFM), scanning electron microscopy (SEM), and X-ray diffraction. Macroscopically, the RT samples appeared semi-transparent and smooth, whereas the FD group exhibited an opaque white color and sponge-like structure. SEM examination showed denser packing of fibrils in FD samples while RT-samples displayed smaller average fiber diameter, lower surface roughness and less porosity. AFM confirmed the SEM observations and showed that the FD material exhibited a more branched structure and a higher surface roughness. The samples cultivated in a glucose-containing nutrient medium, generally displayed a straight and ordered shape of fibrils compared to the sucrose-derived BC, characterized by a rougher and wavier structure. The BC films dried under different conditions showed distinctly different crystallinity degrees, whereas the carbon source in the culture medium was found to have a relatively small effect on the BC crystallinity.}, language = {en} } @article{AkimbekovZhubanovaMansurovetal.2010, author = {Akimbekov, Nuraly S. and Zhubanova, A. A. and Mansurov, Z. A. and Digel, Ilya and Artmann, Gerhard and Temiz Artmann, Ayseg{\"u}l}, title = {Use of Carbonized Rise Shell for the local treatment of wounds}, series = {Eurasian ChemTech Journal}, volume = {12}, journal = {Eurasian ChemTech Journal}, number = {2}, publisher = {Institute of Combustion Problems}, address = {Almaty}, issn = {2522-4867}, doi = {10.18321/ectj35}, pages = {133 -- 138}, year = {2010}, abstract = {On the model of musculocutaneous wound in rats, the effect of applicative sorption by carbonized rise shell (CRS) on the healing of festering wound was studied. It has been shown, that cytological changes end with rapid scar formation. The use of CRS at the period of severe purulent wound contributes to its favorable course, prevents the development of complications of the animals from sepsis.}, language = {en} } @article{AkimbekovDigelO’Herasetal.2015, author = {Akimbekov, Nuraly S. and Digel, Ilya and O'Heras, C. and Tastambek, K.T. and Savitskaya, I.S. and Ualyeva, P.S. and Mansurov, Z.A. and Zhubanova, A.A.}, title = {Adsorption of bacterial lipopol ysaccharides on carbonized ri ce husks obtained in the batch experiments}, series = {KazNU Bulletin. Biology series}, volume = {60}, journal = {KazNU Bulletin. Biology series}, number = {No 1/2}, issn = {1563-0218}, pages = {144 -- 148}, year = {2015}, language = {en} } @article{DigelZhubanovaNojimaetal.2004, author = {Digel, Ilya and Zhubanova, Azhar A. and Nojima, H. and Artmann, Gerhard}, title = {The use of bactericidal effects of cluster ions generated by plasma in medical biotechnology}, series = {Biotechnologija : teorija i praktika (2004)}, journal = {Biotechnologija : teorija i praktika (2004)}, isbn = {1028-9399}, pages = {46 -- 52}, year = {2004}, language = {en} } @article{ArtmannZerlinDigeletal.2007, author = {Artmann, Gerhard and Zerlin, Kay and Digel, Ilya and Stadler, Andreas M.}, title = {Physical discontinuities at body temperature in human red blood cells / Artmann, GM ; Zerlin, K ; Digel, I ; Stadler, A ; Zaccai, G ; Temiz, AA}, series = {Tissue Engineering. 13 (2007), H. 7}, journal = {Tissue Engineering. 13 (2007), H. 7}, isbn = {1076-3279}, pages = {1778 -- 1778}, year = {2007}, language = {en} } @article{TurlybekulyPogrebnjakSukhodubetal.2019, author = {Turlybekuly, Amanzhol and Pogrebnjak, Alexander and Sukhodub, L. F. and Sukhodub, Liudmyla B. and Kistaubayeva, A. S. and Savitskaya, Irina and Shokatayeva, D. H. and Bondar, Oleksandr V. and Shaimardanov, Z. K. and Plotnikov, Sergey V. and Shaimardanova, B. H. and Digel, Ilya}, title = {Synthesis, characterization, in vitro biocompatibility and antibacterial properties study of nanocomposite materials based on hydroxyapatite-biphasic ZnO micro- and nanoparticles embedded in Alginate matrix}, series = {Materials Science and Engineering C}, volume = {104}, journal = {Materials Science and Engineering C}, number = {Article number 109965}, publisher = {Elsevier}, address = {Amsterdam}, doi = {10.1016/j.msec.2019.109965}, year = {2019}, language = {en} } @article{KarnatakKantzBialonski2017, author = {Karnatak, Rajat and Kantz, Holger and Bialonski, Stephan}, title = {Early warning signal for interior crises in excitable systems}, series = {Physical Review E}, volume = {96}, journal = {Physical Review E}, number = {4}, issn = {2470-0053}, doi = {10.1103/PhysRevE.96.042211}, pages = {042211}, year = {2017}, language = {en} } @article{LeimenaArtmannDachwaldetal.2010, author = {Leimena, W. and Artmann, Gerhard and Dachwald, Bernd and Temiz Artmann, Ayseg{\"u}l and Gossmann, Matthias and Digel, Ilya}, title = {Feasibility of an in-situ microbial decontamination of an ice-melting probe}, series = {Eurasian Chemico-Technological Journal. 12 (2010), H. 2}, journal = {Eurasian Chemico-Technological Journal. 12 (2010), H. 2}, isbn = {1562-3920}, pages = {145 -- 150}, year = {2010}, language = {en} } @article{BassamDigelHescheleretal.2013, author = {Bassam, Rasha and Digel, Ilya and Hescheler, J{\"u}rgen and Temiz Artmann, Ayseg{\"u}l and Artmann, Gerhard}, title = {Effects of spermine NONOate and ATP on protein aggregation: light scattering evidences}, series = {BMC Biophysics}, journal = {BMC Biophysics}, publisher = {BioMed Central}, address = {London}, isbn = {2046-1682}, url = {http://nbn-resolving.de/10.1186/2046-1682-6-1}, pages = {1 -- 14}, year = {2013}, language = {en} } @article{TuraliyevaYeshibaevSaparbekovaetal.2016, author = {Turaliyeva, M. and Yeshibaev, A. and Saparbekova, A. and Akynova, L. and Abildayeva, R. and Sadenova, M. and Sartayeva, K. and Schieffer, Andre and Digel, Ilya}, title = {Species composition and injuriousness of stranger xylophilous fauna affecting indigenous urban dendroflora of Central Asia}, series = {Asian journal of microbiology, biotechnology \& environmental sciences : AJMBES}, volume = {18}, journal = {Asian journal of microbiology, biotechnology \& environmental sciences : AJMBES}, number = {2}, publisher = {EM International}, issn = {0972-3005}, pages = {359 -- 366}, year = {2016}, abstract = {At the present time, one of the most serious environmental problems of Central Asia and South Kazakhstan is the ongoing large-scale deterioration of principal urban tree populations. Several major centers of massive spread of invasive plant pests have been found in urban dendroflora of this region. The degree of damage of seven most wide-spread aboriginal tree species was found to range from 21.4±1.1 to 85.4±1.8\%. In particular, the integrity of the native communities of sycamore (Platanus spp.), willow (Salix spp.), poplar (Populus spp.) and elm (Ulmus spp.) is highly endangered. Our taxonomic analysis of the most dangerous tree pests of the region has revealed them as neobiontic xylophilous insects such as Cossus cossus L. (Order: Lepidoptera L.) Monochamus urussovi Fisch., Monochamus sutor L., Acanthocinus aedelis L. and {\~N}etonia aureate L. (Order: Coleoptera L.). We relate the origin of this threatening trend with the import of industrial wood in the mid 90’s of the last century that was associated with high degree of the constructional work in the region. Because of the absence of efficient natural predators of the pest species, the application of microbiological methods of the pest control and limitation is suggested.}, language = {en} } @article{VuStaat2004, author = {Vu, Duc-Khoi and Staat, Manfred}, title = {An algorithm for shakedown analysis of structure with temperature dependent yield stress}, year = {2004}, abstract = {This work is an attempt to answer the question: How to use convex programming in shakedown analysis of structures made of materials with temperature-dependent properties. Based on recently established shakedown theorems and formulations, a dual relationship between upper and lower bounds of the shakedown limit load is found, an algorithmfor shakedown analysis is proposed. While the original problem is neither convex nor concave, the algorithm presented here has the advantage of employing convex programming tools.}, subject = {Einspielen }, language = {en} } @article{CiritsisHorbachStaatetal.2018, author = {Ciritsis, Alexander and Horbach, Andreas and Staat, Manfred and Kuhl, Christiane K. and Kraemer, Nils Andreas}, title = {Porosity and tissue integration of elastic mesh implants evaluated in vitro and in vivo}, series = {Journal of Biomedical Materials Research: Part B: Applied Biomaterials}, volume = {106}, journal = {Journal of Biomedical Materials Research: Part B: Applied Biomaterials}, number = {2}, publisher = {Wiley}, address = {New York, NY}, issn = {1552-4981}, doi = {10.1002/jbm.b.33877}, pages = {827 -- 833}, year = {2018}, abstract = {Purpose In vivo, a loss of mesh porosity triggers scar tissue formation and restricts functionality. The purpose of this study was to evaluate the properties and configuration changes as mesh deformation and mesh shrinkage of a soft mesh implant compared with a conventional stiff mesh implant in vitro and in a porcine model. Material and Methods Tensile tests and digital image correlation were used to determine the textile porosity for both mesh types in vitro. A group of three pigs each were treated with magnetic resonance imaging (MRI) visible conventional stiff polyvinylidene fluoride meshes (PVDF) or with soft thermoplastic polyurethane meshes (TPU) (FEG Textiltechnik mbH, Aachen, Germany), respectively. MRI was performed with a pneumoperitoneum at a pressure of 0 and 15 mmHg, which resulted in bulging of the abdomen. The mesh-induced signal voids were semiautomatically segmented and the mesh areas were determined. With the deformations assessed in both mesh types at both pressure conditions, the porosity change of the meshes after 8 weeks of ingrowth was calculated as an indicator of preserved elastic properties. The explanted specimens were examined histologically for the maturity of the scar (collagen I/III ratio). Results In TPU, the in vitro porosity increased constantly, in PVDF, a loss of porosity was observed under mild stresses. In vivo, the mean mesh areas of TPU were 206.8 cm2 (± 5.7 cm2) at 0 mmHg pneumoperitoneum and 274.6 cm2 (± 5.2 cm2) at 15 mmHg; for PVDF the mean areas were 205.5 cm2 (± 8.8 cm2) and 221.5 cm2 (± 11.8 cm2), respectively. The pneumoperitoneum-induced pressure increase resulted in a calculated porosity increase of 8.4\% for TPU and of 1.2\% for PVDF. The mean collagen I/III ratio was 8.7 (± 0.5) for TPU and 4.7 (± 0.7) for PVDF. Conclusion The elastic properties of TPU mesh implants result in improved tissue integration compared to conventional PVDF meshes, and they adapt more efficiently to the abdominal wall. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 827-833, 2018.}, language = {en} } @article{StaatBallmann1988, author = {Staat, Manfred and Ballmann, J.}, title = {Computation of impacts on elastic solids by methods of bicharacteristics}, series = {Computational Mechanics '88 : theory and applications ; proceedings of the International Conference on Computational Engineering Science April 10-14, 1988, Atlanta, GA, USA ; vol. 2}, journal = {Computational Mechanics '88 : theory and applications ; proceedings of the International Conference on Computational Engineering Science April 10-14, 1988, Atlanta, GA, USA ; vol. 2}, pages = {1719 -- 1722}, year = {1988}, abstract = {Shock waves, explosions, impacts or cavitation bubble collapses may generate stress waves in solids causing cracks or unexpected dammage due to focussing, physical nonlinearity or interaction with existing cracks. There is a growing interest in wave propagation, which poses many novel problems to experimentalists and theorists.}, subject = {Bicharakteristikenverfahren}, language = {en} } @article{Staat2000, author = {Staat, Manfred}, title = {Basis Reduction for the Shakedown Problem for Bounded Kinematic Hardening Material}, year = {2000}, abstract = {Limit and shakedown analysis are effective methods for assessing the load carrying capacity of a given structure. The elasto-plastic behavior of the structure subjected to loads varying in a given load domain is characterized by the shakedown load factor, defined as the maximum factor which satisfies the sufficient conditions stated in the corresponding static shakedown theorem. The finite element dicretization of the problem may lead to very large convex optimization. For the effective solution a basis reduction method has been developed that makes use of the special problem structure for perfectly plastic material. The paper proposes a modified basis reduction method for direct application to the two-surface plasticity model of bounded kinematic hardening material. The considered numerical examples show an enlargement of the load carrying capacity due to bounded hardening.}, subject = {Finite-Elemente-Methode}, language = {en} } @article{StaatHeitzerLangetal.2005, author = {Staat, Manfred and Heitzer, M. and Lang, H. and Wirtz, K.}, title = {Direct Finite Element Route for Design-by-Analysis of Pressure Components}, series = {International Journal of Pressure Vessels and Piping. 82 (2005), H. 1}, journal = {International Journal of Pressure Vessels and Piping. 82 (2005), H. 1}, isbn = {0308-0161}, pages = {61 -- 67}, year = {2005}, language = {en} } @article{PogorelovaRogachevDigeletal.2020, author = {Pogorelova, Natalia and Rogachev, Evgeniy and Digel, Ilya and Chernigova, Svetlana and Nardin, Dmitry}, title = {Bacterial Cellulose Nanocomposites: Morphology and Mechanical Properties}, series = {Materials}, volume = {13}, journal = {Materials}, number = {12}, publisher = {MDPI}, address = {Basel}, isbn = {1996-1944}, doi = {10.3390/ma13122849}, pages = {1 -- 16}, year = {2020}, abstract = {Bacterial cellulose (BC) is a promising material for biomedical applications due to its unique properties such as high mechanical strength and biocompatibility. This article describes the microbiological synthesis, modification, and characterization of the obtained BC-nanocomposites originating from symbiotic consortium Medusomyces gisevii. Two BC-modifications have been obtained: BC-Ag and BC-calcium phosphate (BC-Ca3(PO4)2). Structure and physicochemical properties of the BC and its modifications were investigated by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), and infrared Fourier spectroscopy as well as by measurements of mechanical and water holding/absorbing capacities. Topographic analysis of the surface revealed multicomponent thick fibrils (150-160 nm in diameter and about 15 µm in length) constituted by 50-60 nm nanofibrils weaved into a left-hand helix. Distinctive features of Ca-phosphate-modified BC samples were (a) the presence of 500-700 nm entanglements and (b) inclusions of Ca3(PO4)2 crystals. The samples impregnated with Ag nanoparticles exhibited numerous roundish inclusions, about 110 nm in diameter. The boundaries between the organic and inorganic phases were very distinct in both cases. The Ag-modified samples also showed a prominent waving pattern in the packing of nanofibrils. The obtained BC gel films possessed water-holding capacity of about 62.35 g/g. However, the dried (to a constant mass) BC-films later exhibited a low water absorption capacity (3.82 g/g). It was found that decellularized BC samples had 2.4 times larger Young's modulus and 2.2 times greater tensile strength as compared to dehydrated native BC films. We presume that this was caused by molecular compaction of the BC structure.}, language = {en} } @article{HacklAndermahrStaatetal.2017, author = {Hackl, M. and Andermahr, J. and Staat, Manfred and Bremer, I. and Borggrefe, J. and Prescher, A. and M{\"u}ller, L. P. and Wegmann, K.}, title = {Suture button reconstruction of the central band of the interosseous membrane in Essex-Lopresti lesions: a comparative biomechanical investigation}, series = {The Journal of Hand Surgery (European Volume)}, volume = {42}, journal = {The Journal of Hand Surgery (European Volume)}, number = {4}, publisher = {Sage}, address = {London}, issn = {2043-6289 (Online)}, doi = {10.1177/1753193416665943}, pages = {370 -- 376}, year = {2017}, language = {en} } @article{GoeddekeStrzodkaMohdYusofetal.2007, author = {G{\"o}ddeke, Dominik and Strzodka, Robert and Mohd-Yusof, Jamaludin and McCormick, Patrick and Buijssen, Sven H.M. and Grajewski, Matthias and Turek, Stefan}, title = {Exploring weak scalability for FEM calculations on a GPU-enhanced cluster}, series = {Parallel Computing}, volume = {33}, journal = {Parallel Computing}, number = {10-11}, issn = {0167-8191}, doi = {10.1016/j.parco.2007.09.002}, pages = {685 -- 699}, year = {2007}, language = {en} } @article{StulpeHellwig1993, author = {Stulpe, Werner and Hellwig, K.-E.}, title = {A Classical Reformulation of Finite-Dimensional Quantum Mechanics. Hellwig, K.-E.; Stulpe, W.}, series = {Quantum measurement, irreversibility and the physics of information / Symposium on the Foundations of Modern Physics 1993, Cologne, Germany 1 - 5 June 1993. Ed. Paul Busch}, journal = {Quantum measurement, irreversibility and the physics of information / Symposium on the Foundations of Modern Physics 1993, Cologne, Germany 1 - 5 June 1993. Ed. Paul Busch}, publisher = {World Scientific}, address = {Singapore [u.a.]}, isbn = {981021507X}, pages = {209 -- 214}, year = {1993}, language = {en} } @article{Staat2001, author = {Staat, Manfred}, title = {LISA - a European project for FEM-based limit and shakedown analysis}, year = {2001}, abstract = {The load-carrying capacity or the safety against plastic limit states are the central questions in the design of structures and passive components in the apparatus engineering. A precise answer is most simply given by limit and shakedown analysis. These methods can be based on static and kinematic theorems for lower and upper bound analysis. Both may be formulated as optimization problems for finite element discretizations of structures. The problems of large-scale analysis and the extension towards realistic material modelling will be solved in a European research project. Limit and shakedown analyses are briefly demonstrated with illustrative examples.}, subject = {Einspielen }, language = {en} } @article{TopcuMadabhushiStaat2022, author = {Top{\c{c}}u, Murat and Madabhushi, Gopal S.P. and Staat, Manfred}, title = {A generalized shear-lag theory for elastic stress transfer between matrix and fibres having a variable radius}, series = {International Journal of Solids and Structures}, volume = {239-240}, journal = {International Journal of Solids and Structures}, number = {Art. No. 111464}, publisher = {Elsevier}, address = {New York, NY}, issn = {0020-7683}, doi = {10.1016/j.ijsolstr.2022.111464}, year = {2022}, abstract = {A generalized shear-lag theory for fibres with variable radius is developed to analyse elastic fibre/matrix stress transfer. The theory accounts for the reinforcement of biological composites, such as soft tissue and bone tissue, as well as for the reinforcement of technical composite materials, such as fibre-reinforced polymers (FRP). The original shear-lag theory proposed by Cox in 1952 is generalized for fibres with variable radius and with symmetric and asymmetric ends. Analytical solutions are derived for the distribution of axial and interfacial shear stress in cylindrical and elliptical fibres, as well as conical and paraboloidal fibres with asymmetric ends. Additionally, the distribution of axial and interfacial shear stress for conical and paraboloidal fibres with symmetric ends are numerically predicted. The results are compared with solutions from axisymmetric finite element models. A parameter study is performed, to investigate the suitability of alternative fibre geometries for use in FRP.}, language = {en} } @article{BhattaraiHorbachStaatetal.2022, author = {Bhattarai, Aroj and Horbach, Andreas and Staat, Manfred and Kowalczyk, Wojciech and Tran, Thanh Ngoc}, title = {Virgin passive colon biomechanics and a literature review of active contraction constitutive models}, series = {Biomechanics}, volume = {2}, journal = {Biomechanics}, number = {2}, publisher = {MDPI}, address = {Basel}, issn = {2673-7078}, doi = {10.3390/biomechanics2020013}, pages = {138 -- 157}, year = {2022}, abstract = {The objective of this paper is to present our findings on the biomechanical aspects of the virgin passive anisotropic hyperelasticity of the porcine colon based on equibiaxial tensile experiments. Firstly, the characterization of the intestine tissues is discussed for a nearly incompressible hyperelastic fiber-reinforced Holzapfel-Gasser-Ogden constitutive model in virgin passive loading conditions. The stability of the evaluated material parameters is checked for the polyconvexity of the adopted strain energy function using positive eigenvalue constraints of the Hessian matrix with MATLAB. The constitutive material description of the intestine with two collagen fibers in the submucosal and muscular layer each has been implemented in the FORTRAN platform of the commercial finite element software LS-DYNA, and two equibiaxial tensile simulations are presented to validate the results with the optical strain images obtained from the experiments. Furthermore, this paper also reviews the existing models of the active smooth muscle cells, but these models have not been computationally studied here. The review part shows that the constitutive models originally developed for the active contraction of skeletal muscle based on Hill's three-element model, Murphy's four-state cross-bridge chemical kinetic model and Huxley's sliding-filament hypothesis, which are mainly used for arteries, are appropriate for numerical contraction numerical analysis of the large intestine.}, language = {en} } @article{AbelKahmannMellonetal.2020, author = {Abel, Alexander and Kahmann, Stephanie Lucina and Mellon, Stephen and Staat, Manfred and Jung, Alexander}, title = {An open-source tool for the validation of finite element models using three-dimensional full-field measurements}, series = {Medical Engineering \& Physics}, volume = {77}, journal = {Medical Engineering \& Physics}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1350-4533}, doi = {10.1016/j.medengphy.2019.10.015}, pages = {125 -- 129}, year = {2020}, abstract = {Three-dimensional (3D) full-field measurements provide a comprehensive and accurate validation of finite element (FE) models. For the validation, the result of the model and measurements are compared based on two respective point-sets and this requires the point-sets to be registered in one coordinate system. Point-set registration is a non-convex optimization problem that has widely been solved by the ordinary iterative closest point algorithm. However, this approach necessitates a good initialization without which it easily returns a local optimum, i.e. an erroneous registration. The globally optimal iterative closest point (Go-ICP) algorithm has overcome this drawback and forms the basis for the presented open-source tool that can be used for the validation of FE models using 3D full-field measurements. The capability of the tool is demonstrated using an application example from the field of biomechanics. Methodological problems that arise in real-world data and the respective implemented solution approaches are discussed.}, language = {en} } @article{VoegeleGrajewskiGovorukhaetal.2020, author = {V{\"o}gele, Stefan and Grajewski, Matthias and Govorukha, Kristina and R{\"u}bbelke, Dirk}, title = {Challenges for the European steel industry: Analysis, possible consequences and impacts on sustainable development}, series = {Applied Energy}, volume = {264}, journal = {Applied Energy}, number = {Article number: 114633}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0306-2619}, doi = {10.1016/j.apenergy.2020.114633}, year = {2020}, abstract = {The steel industry in the European Union (EU), important for the economy as a whole, faces various challenges. These are inter alia volatile prices for relevant input factors, uncertainties concerning the regulation of CO₂-emissions and market shocks caused by the recently introduced additional import duties in the US, which is an important sales market. We examine primary and secondary effects of these challenges on the steel industry in the EU and their impacts on European and global level. Developing and using a suitable meta-model, we analyze the competitiveness of key steel producing countries with respect to floor prices depending on selected cost factors and draw conclusions on the impacts in the trade of steel on emissions, energy demand, on the involvement of developing countries in the value chain as well on the need for innovations to avoid relocations of production. Hence, our study contributes to the assessment of sustainable industrial development, which is aimed by the Sustainability Development Goal "Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation countries". By applying information on country-specific Human Development Indexes (reflecting aspects of life expectancy, education, and per capita income), we show that relocating energy-intensive industries from the EU may not only increase global energy demand and CO₂-emissions, but may also be to the disadvantage of developing countries.}, language = {en} } @article{AndingTabazaStaatetal.2013, author = {Anding, Ralf and Tabaza, Ruth and Staat, Manfred and Trenz, Eva and Lohmann, Philipp and Klinge, Uwe and Kirschner-Hermanns, Ruth}, title = {Introducing a method of in vitro testing of different anchoring systems used for female incontinence and prolapse surgery}, series = {BioMed research international}, volume = {Vol. 2013}, journal = {BioMed research international}, issn = {1110-7251 (E-Journal); 2314-6141 (E-Journal); 1110-7243 (Print); 2314-6133 (Print)}, pages = {Article ID 401417}, year = {2013}, language = {en} } @article{HacklLeschingerStaatetal.2016, author = {Hackl, Michael and Leschinger, T. and Staat, Manfred and M{\"u}ller, Lars-Peter and Wegmann, Kilian}, title = {Reconstruction of the interosseous membrane in the Essex Lopresti lesion — a biomechanical evaluation}, series = {Knee surgery, sports traumatology, arthroscopy}, volume = {Volume 24}, journal = {Knee surgery, sports traumatology, arthroscopy}, number = {Supplement 1}, publisher = {Springer}, address = {Berlin}, issn = {0942-2056}, doi = {10.1007/s00167-016-4080-7}, pages = {130 -- 131}, year = {2016}, abstract = {Surgical reconstruction of the interosseous membrane (IOM) could restore longitudinal forearm stability to avoid persisting disability due to capituloradial and ulnocarpal impingement in Essex Lopresti lesions. This biomechanical study aimed to assess longitudinal forearm stability of intact specimens, after sectioning of the IOM and after reconstruction with a TightRope construct using either a single or double bundle technique.}, language = {en} } @article{AkimbekovQiaoDigeletal.2020, author = {Akimbekov, Nuraly S. and Qiao, Xiaohui and Digel, Ilya and Abdieva, Gulzhamal and Ualieva, Perizat and Zhubanova, Azhar}, title = {The effect of leonardite-derived amendments on soil microbiome structure and potato yield}, series = {Agriculture}, volume = {10}, journal = {Agriculture}, number = {Art. 147}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/agriculture10050147}, pages = {1 -- 17}, year = {2020}, abstract = {Humic substances originating from various organic matters can ameliorate soil properties, stimulate plant growth, and improve nutrient uptake. Due to the low calorific heating value, leonardite is rather unsuitable as fuel. However, it may serve as a potential source of humic substances. This study was aimed at characterizing the leonardite-based soil amendments and examining the effect of their application on the soil microbial community, as well as on potato growth and tuber yield. A high yield (71.1\%) of humic acid (LHA) from leonardite has been demonstrated. Parental leonardite (PL) and LHA were applied to soil prior to potato cultivation. The 16S rRNA sequencing of soil samples revealed distinct relationships between microbial community composition and the application of leonardite-based soil amendments. Potato tubers were planted in pots in greenhouse conditions. The tubers were harvested at the mature stage for the determination of growth and yield parameters. The results demonstrated that the LHA treatments had a significant effect on increasing potato growth (54.9\%) and tuber yield (66.4\%) when compared to the control. The findings highlight the importance of amending leonardite-based humic products for maintaining the biogeochemical stability of soils, for keeping their healthy microbial community structure, and for increasing the agronomic productivity of potato plants.}, language = {en} } @article{KuehnHaugnerStaatetal.2004, author = {K{\"u}hn, Raoul-Roman and Haugner, Werner and Staat, Manfred and Sponagel, Stefan}, title = {A Two Phase Mixture Model based on Bone Observation}, year = {2004}, abstract = {An optimization method is developed to describe the mechanical behaviour of the human cancellous bone. The method is based on a mixture theory. A careful observation of the behaviour of the bone material leads to the hypothesis that the bone density is controlled by the principal stress trajectories (Wolff's law). The basic idea of the developed method is the coupling of a scalar value via an eigenvalue problem to the principal stress trajectories. On the one hand this theory will permit a prediction of the reaction of the biological bone structure after the implantation of a prosthesis, on the other hand it may be useful in engineering optimization problems. An analytical example shows its efficiency.}, subject = {Knochen}, language = {en} } @article{WegmannHacklStaatetal.2016, author = {Wegmann, Kilian and Hackl, Michael and Staat, Manfred and Mayer, Katharina and M{\"u}ller, Lars-Peter}, title = {Double plate osteosynthesis of proximal ulna fractures: biomechanical and clinical results}, series = {Knee surgery, sports traumatology, arthroscopy}, volume = {Volume 24}, journal = {Knee surgery, sports traumatology, arthroscopy}, number = {Supplement 1}, publisher = {Springer}, address = {Berlin}, issn = {0942-2056}, doi = {10.1007/s00167-016-4079-0}, pages = {58 -- 59}, year = {2016}, abstract = {While plate fixation of proximal ulna fractures might lead to superior clinical results compared to tension band wiring, regular plates represent an established risk factor for wound complications. The olecranon double plates (Medartis, Basel, CH) might decrease complications related to the osteosynthesis because of their low profile and better anatomical fit. This study aimed to evaluate the biomechanical performance and clinical results of the olecranon double plates.}, language = {en} } @article{JungStaatMueller2013, author = {Jung, Alexander and Staat, Manfred and M{\"u}ller, Wolfram}, title = {Flight style optimization in ski jumping on normal, large, and ski flying hills}, series = {Journal of biomechanics}, volume = {Vol. 47}, journal = {Journal of biomechanics}, number = {Iss. 3}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1873-2380 (E-Journal); 0021-9290 (Print)}, pages = {716 -- 722}, year = {2013}, language = {en} } @article{ArtmannDigelLinderetal.2008, author = {Artmann, Gerhard and Digel, Ilya and Linder, Peter and Porst, Dariusz}, title = {Mechanism of haemoglobin sensing body temperature}, series = {Tissue Engineering Part A. 14 (2008), H. 5}, journal = {Tissue Engineering Part A. 14 (2008), H. 5}, isbn = {1937-3341}, pages = {754 -- 754}, year = {2008}, language = {en} } @article{BronderPoghossianSchejaetal.2015, author = {Bronder, Thomas and Poghossian, Arshak and Scheja, S. and Wu, Chunsheng and Keusgen, M. and Sch{\"o}ning, Michael Josef}, title = {Electrostatic Detection of Unlabelled Single- and Double-stranded DNA Using Capacitive Field-effect Devices Functionalized with a Positively Charged Polyelectrolyte Layer}, series = {Procedia Engineering}, volume = {120}, journal = {Procedia Engineering}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1877-7058}, doi = {10.1016/j.proeng.2015.08.710}, pages = {544 -- 547}, year = {2015}, abstract = {Capacitive field-effect electrolyte-insulator-semiconductor sensors consisting of an Al-p-Si-SiO2 structure have been used for the electrical detection of unlabelled single- and double-stranded DNA (dsDNA) molecules by their intrinsic charge. A simple functionalization protocol based on the layer-by-layer (LbL) technique was used to prepare a weak polyelectrolyte/probe-DNA bilayer, followed by the hybridization with complementary target DNA molecules. Due to the flat orientation of the LbL-adsorbed DNA molecules, a high sensor signal has been achieved. In addition, direct label-free detection of in-solution hybridized dsDNA molecules has been studied.}, language = {en} } @article{PoghossianIngebrandtAbouzaretal.2007, author = {Poghossian, Arshak and Ingebrandt, S. and Abouzar, Maryam H. and Sch{\"o}ning, Michael Josef}, title = {Label-free detection of charged macromolecules by using a field-effect-based sensor platform: Experiments and possible mechanisms of signal generation}, series = {Applied Physics A: Materials Science \& Processing. 87 (2007), H. 3}, journal = {Applied Physics A: Materials Science \& Processing. 87 (2007), H. 3}, isbn = {0947-8396}, pages = {517 -- 524}, year = {2007}, language = {en} } @article{MolinnusSorichBartzetal.2016, author = {Molinnus, Denise and Sorich, Maren and Bartz, Alexander and Siegert, Petra and Willenberg, Holger S. and Lisdat, Fred and Poghossian, Arshak and Keusgen, Michael and Sch{\"o}ning, Michael Josef}, title = {Towards an adrenaline biosensor based on substrate recycling amplification in combination with an enzyme logic gate}, series = {Sensors and Actuators B: Chemical}, volume = {237}, journal = {Sensors and Actuators B: Chemical}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0925-4005}, doi = {10.1016/j.snb.2016.06.064}, pages = {190 -- 195}, year = {2016}, abstract = {An amperometric biosensor using a substrate recycling principle was realized for the detection of low adrenaline concentrations (1 nM) by measurements in phosphate buffer and Ringer's solution at pH 6.5 and pH 7.4, respectively. In proof-of-concept experiments, a Boolean logic-gate principle has been applied to develop a digital adrenaline biosensor based on an enzyme AND logic gate. The obtained results demonstrate that the developed digital biosensor is capable for a rapid qualitative determination of the presence/absence of adrenaline in a YES/NO statement. Such digital biosensor could be used in clinical diagnostics for the control of a correct insertion of a catheter in the adrenal veins during adrenal venous-sampling procedure.}, language = {en} } @article{PoghossianKatzSchoening2015, author = {Poghossian, Arshak and Katz, Evgeny and Sch{\"o}ning, Michael Josef}, title = {Enzyme logic AND-Reset and OR-Reset gates based on a field-effect electronic transducer modified with multi-enzyme membrane}, series = {Chemical Communications}, volume = {51}, journal = {Chemical Communications}, publisher = {Royal Society of Chemistry (RSC)}, address = {Cambridge}, doi = {10.1039/C5CC01362C}, pages = {6564 -- 6567}, year = {2015}, abstract = {Capacitive field-effect sensors modified with a multi-enzyme membrane have been applied for an electronic transduction of biochemical signals processed by enzyme-based AND-Reset and OR-Reset logic gates. The local pH change at the sensor surface induced by the enzymatic reaction was used for the activation of the Reset function for the first time.}, language = {en} } @article{AbouzarPoghossianRazavietal.2009, author = {Abouzar, Maryam H. and Poghossian, Arshak and Razavi, A. and Williams, O. A. and Bijnens, N. and Wagner, P. and Sch{\"o}ning, Michael Josef}, title = {Characterisation of capacitive field-effect sensors with a nanocrystalline-diamond film as transducer material for multi-parameter sensing}, series = {Biosensors and Bioelectronics. 24 (2009), H. 5}, journal = {Biosensors and Bioelectronics. 24 (2009), H. 5}, publisher = {Elsevier}, address = {Amsterdam}, isbn = {0956-5663}, pages = {1298 -- 1304}, year = {2009}, language = {en} } @article{TurekKeusgenPoghossianetal.2008, author = {Turek, M. and Keusgen, M. and Poghossian, Arshak and Mulchandani, A. and Wang, J. and Sch{\"o}ning, Michael Josef}, title = {Enzyme-modified electrolyte-insulator-semiconductor sensors}, series = {Journal of Contemporary Physics. 43 (2008), H. 2}, journal = {Journal of Contemporary Physics. 43 (2008), H. 2}, isbn = {1934-9378}, pages = {82 -- 85}, year = {2008}, language = {en} } @article{PoghossianIngebrandtYeungetal.2004, author = {Poghossian, Arshak and Ingebrandt, S. and Yeung, C.-K. and Offenh{\"a}usser, A. and Sch{\"o}ning, Michael Josef}, title = {Microsensors based on ion-sensitive field-effect transistors for biomedical applications}, series = {Biomedizinische Technik. 49 (2004), H. 2}, journal = {Biomedizinische Technik. 49 (2004), H. 2}, isbn = {0932-4666}, pages = {1036 -- 1037}, year = {2004}, language = {en} } @article{BaeckerBegingBisellietal.2009, author = {B{\"a}cker, Matthias and Beging, Stefan and Biselli, Manfred and Poghossian, Arshak and Wang, J. and Zang, Werner and Wagner, Patrick and Sch{\"o}ning, Michael Josef}, title = {Concept for a solid-state multi-parameter sensor system for cell-culture monitoring}, series = {Electrochimica Acta. 54 (2009), H. 25 Sp. Iss. SI}, journal = {Electrochimica Acta. 54 (2009), H. 25 Sp. Iss. SI}, publisher = {Elsevier}, address = {Amsterdam}, isbn = {0013-4686}, pages = {6107 -- 6112}, year = {2009}, language = {en} } @article{BuniatyanMatirosyanAbouzaretal.2009, author = {Buniatyan, Vahe V. and Matirosyan, N. and Abouzar, Maryam H. and Schubert, J. and Zander, W. and Gevorgian, S. and Sch{\"o}ning, Michael Josef and Poghossian, Arshak}, title = {Capacitive field-effect pH sensor based on an electrolyte-ferroelectric-insulator-semiconductor structure}, series = {SENSOR 2009 : : 14th International Conference on Sensors, Technologies, Electronics and Applications; N{\"u}rnberg, Germany, 26 - 28 May 2009; proceedings; [part of] Sensor + Test Conference 2009 / AMA, Fachverband f{\"u}r Sensorik e.V}, journal = {SENSOR 2009 : : 14th International Conference on Sensors, Technologies, Electronics and Applications; N{\"u}rnberg, Germany, 26 - 28 May 2009; proceedings; [part of] Sensor + Test Conference 2009 / AMA, Fachverband f{\"u}r Sensorik e.V}, publisher = {AMA Service}, address = {Wunstorf}, isbn = {9783981099355}, pages = {317 -- 322}, year = {2009}, language = {en} } @article{PoghossianBerndsenSchoening2003, author = {Poghossian, Arshak and Berndsen, Lars and Sch{\"o}ning, Michael Josef}, title = {Chemical sensor as physical sensor: ISFET-based flowvelocity, flow-direction and diffusion-coefficient sensor}, series = {Sensors and Actuators B. 95 (2003), H. 1-3}, journal = {Sensors and Actuators B. 95 (2003), H. 1-3}, isbn = {0925-4005}, pages = {384 -- 390}, year = {2003}, language = {en} } @article{DigelMaggakisKelemenZerlinetal.2006, author = {Digel, Ilya and Maggakis-Kelemen, Christina and Zerlin, Kay and Linder, Peter}, title = {Body temperature-related structural transitions of monotremal and human hemoglobin}, series = {Biophysical Journal. 91 (2006), H. 8}, journal = {Biophysical Journal. 91 (2006), H. 8}, isbn = {1542-0086}, pages = {3014 -- 3021}, year = {2006}, language = {en} } @article{PoghossianWagnerSchoening2011, author = {Poghossian, Arshak and Wagner, Holger and Sch{\"o}ning, Michael Josef}, title = {Functional testing and characterisation of (bio-)chemical sensors on wafer level}, series = {Sensors and Actuators B: Chemical. 154 (2011), H. 2}, journal = {Sensors and Actuators B: Chemical. 154 (2011), H. 2}, publisher = {Elsevier}, address = {Amsterdam}, isbn = {1873-3077}, pages = {169 -- 173}, year = {2011}, language = {en} } @article{PoghossianBerndsenSchultzeetal.2001, author = {Poghossian, Arshak and Berndsen, L. and Schultze, J. W. and L{\"u}th, H. and Sch{\"o}ning, Michael Josef}, title = {„High order" hybrid sensor module based on an identical transducer principle}, series = {Chemical and biological sensors and analytical methods : proceedings of the international symposium / Sensor, Physical Electrochemistry, and Organic and Biological Electrochemistry Divisions. Ed.: M. Butler}, journal = {Chemical and biological sensors and analytical methods : proceedings of the international symposium / Sensor, Physical Electrochemistry, and Organic and Biological Electrochemistry Divisions. Ed.: M. Butler}, publisher = {Electrochemical Society}, address = {Pennington, NJ}, isbn = {1-56677-351-2}, pages = {143 -- 152}, year = {2001}, language = {en} } @article{PoghossianThustSchrothetal.2001, author = {Poghossian, Arshak and Thust, M. and Schroth, P. and Steffen, A. and L{\"u}th, H. and Sch{\"o}ning, Michael Josef}, title = {Penicillin detection by means of silicon-based field-effect structures}, series = {Sensors and Materials. 13 (2001), H. 4}, journal = {Sensors and Materials. 13 (2001), H. 4}, isbn = {0392-2510}, pages = {207 -- 223}, year = {2001}, language = {en} } @article{TranTrinhDaoetal.2022, author = {Tran, Ngoc Trinh and Trinh, Tu Luc and Dao, Ngoc Tien and Giap, Van Tan and Truong, Manh Khuyen and Dinh, Thuy Ha and Staat, Manfred}, title = {FEM shakedown analysis of structures under random strength with chance constrained programming}, series = {Vietnam Journal of Mechanics}, volume = {44}, journal = {Vietnam Journal of Mechanics}, number = {4}, publisher = {Vietnam Academy of Science and Technology (VAST)}, issn = {0866-7136}, doi = {10.15625/0866-7136/17943}, pages = {459 -- 473}, year = {2022}, abstract = {Direct methods, comprising limit and shakedown analysis, are a branch of computational mechanics. They play a significant role in mechanical and civil engineering design. The concept of direct methods aims to determine the ultimate load carrying capacity of structures beyond the elastic range. In practical problems, the direct methods lead to nonlinear convex optimization problems with a large number of variables and constraints. If strength and loading are random quantities, the shakedown analysis can be formulated as stochastic programming problem. In this paper, a method called chance constrained programming is presented, which is an effective method of stochastic programming to solve shakedown analysis problems under random conditions of strength. In this study, the loading is deterministic, and the strength is a normally or lognormally distributed variable.}, language = {en} } @article{BaeckerPoghossianAbouzaretal.2010, author = {B{\"a}cker, Matthias and Poghossian, Arshak and Abouzar, Maryam H. and Wenmackers, Sylvia and Janssens, Stoffel D. and Haenen, Ken and Wagner, Patrick and Sch{\"o}ning, Michael Josef}, title = {Capacitive field-effect (bio-)chemical sensors based on nanocrystalline diamond films}, series = {Diamond Electronics and Bioelectronics — Fundamentals to Applications III, edited by P. Bergonzo, [u.a.]}, journal = {Diamond Electronics and Bioelectronics — Fundamentals to Applications III, edited by P. Bergonzo, [u.a.]}, pages = {1 -- 6}, year = {2010}, language = {en} } @article{ZerlinKasischkeDigeletal.2007, author = {Zerlin, Kay and Kasischke, Nicole and Digel, Ilya and Maggakis-Kelemen, Christina and Temiz Artmann, Ayseg{\"u}l and Porst, Dariusz and Kayser, Peter and Linder, Peter and Artmann, Gerhard}, title = {Structural transition temperature of hemoglobins correlates with species' body temperature}, series = {European Biophysics Journal. 37 (2007), H. 1}, journal = {European Biophysics Journal. 37 (2007), H. 1}, isbn = {1432-1017}, pages = {1 -- 10}, year = {2007}, language = {en} } @article{LaackRefisch1989, author = {Laack, Walter van and Refisch, A.}, title = {Neuralgic amyotrophy of the lumbar area. Case Report / Refisch, A. ; Laack, W. van}, series = {Archives of Orthopaedic and Trauma Surgery. 108 (1989), H. 5}, journal = {Archives of Orthopaedic and Trauma Surgery. 108 (1989), H. 5}, isbn = {0936-8051}, pages = {329 -- 332}, year = {1989}, language = {en} } @article{Digel2011, author = {Digel, Ilya}, title = {Primary thermosensory events in cells}, series = {Transient receptor potential channels / Md. Shahidul Islam, ed.}, journal = {Transient receptor potential channels / Md. Shahidul Islam, ed.}, publisher = {Springer}, address = {Dordrecht [u.a.]}, isbn = {978-94-007-0264-6}, pages = {451 -- 468}, year = {2011}, language = {en} } @article{SchoeningNaetherAugeretal.2005, author = {Sch{\"o}ning, Michael Josef and N{\"a}ther, Niko and Auger, V. and Poghossian, Arshak and Koudelka-Hep, M.}, title = {Miniaturised flow-through cell with integrated capacitive EIS sensor fabricated at wafer level using Si and SU-8 technologies}, series = {Sensors and Actuators B. 108 (2005), H. 1-2}, journal = {Sensors and Actuators B. 108 (2005), H. 1-2}, isbn = {0925-4005}, pages = {986 -- 992}, year = {2005}, language = {en} } @article{JablonskiPoghossianKeusgenetal.2021, author = {Jablonski, Melanie and Poghossian, Arshak and Keusgen, Michael and Wege, Christina and Sch{\"o}ning, Michael Josef}, title = {Detection of plant virus particles with a capacitive field-effect sensor}, series = {Analytical and Bioanalytical Chemistry}, volume = {413}, journal = {Analytical and Bioanalytical Chemistry}, publisher = {Springer Nature}, address = {Cham}, issn = {1618-2650}, doi = {10.1007/s00216-021-03448-8}, pages = {5669 -- 5678}, year = {2021}, abstract = {Plant viruses are major contributors to crop losses and induce high economic costs worldwide. For reliable, on-site and early detection of plant viral diseases, portable biosensors are of great interest. In this study, a field-effect SiO2-gate electrolyte-insulator-semiconductor (EIS) sensor was utilized for the label-free electrostatic detection of tobacco mosaic virus (TMV) particles as a model plant pathogen. The capacitive EIS sensor has been characterized regarding its TMV sensitivity by means of constant-capacitance method. The EIS sensor was able to detect biotinylated TMV particles from a solution with a TMV concentration as low as 0.025 nM. A good correlation between the registered EIS sensor signal and the density of adsorbed TMV particles assessed from scanning electron microscopy images of the SiO2-gate chip surface was observed. Additionally, the isoelectric point of the biotinylated TMV particles was determined via zeta potential measurements and the influence of ionic strength of the measurement solution on the TMV-modified EIS sensor signal has been studied.}, language = {en} } @article{PoghossianSchoening2021, author = {Poghossian, Arshak and Sch{\"o}ning, Michael Josef}, title = {Recent progress in silicon-based biologically sensitive field-effect devices}, series = {Current Opinion in Electrochemistry}, journal = {Current Opinion in Electrochemistry}, number = {Article number: 100811}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2451-9103}, doi = {10.1016/j.coelec.2021.100811}, year = {2021}, abstract = {Biologically sensitive field-effect devices (BioFEDs) advantageously combine the electronic field-effect functionality with the (bio)chemical receptor's recognition ability for (bio)chemical sensing. In this review, basic and widely applied device concepts of silicon-based BioFEDs (ion-sensitive field-effect transistor, silicon nanowire transistor, electrolyte-insulator-semiconductor capacitor, light-addressable potentiometric sensor) are presented and recent progress (from 2019 to early 2021) is discussed. One of the main advantages of BioFEDs is the label-free sensing principle enabling to detect a large variety of biomolecules and bioparticles by their intrinsic charge. The review encompasses applications of BioFEDs for the label-free electrical detection of clinically relevant protein biomarkers, deoxyribonucleic acid molecules and viruses, enzyme-substrate reactions as well as recording of the cell acidification rate (as an indicator of cellular metabolism) and the extracellular potential.}, language = {en} } @article{PoghossianSchoeningSchrothetal.2001, author = {Poghossian, Arshak and Sch{\"o}ning, Michael Josef and Schroth, P. and Simonis, A. and L{\"u}th, H.}, title = {An ISFET-based penicillin sensor with high sensitivity, low detection limit and long lifetime}, series = {Sensors and Actuators B. 76 (2001), H. 1-3}, journal = {Sensors and Actuators B. 76 (2001), H. 1-3}, isbn = {0925-4005}, pages = {519 -- 526}, year = {2001}, language = {en} } @article{HuckSchiffelsHerreraetal.2013, author = {Huck, Christina and Schiffels, Johannes and Herrera, Cony N. and Schelden, Maximilian and Selmer, Thorsten and Poghossian, Arshak and Baumann, Marcus and Wagner, Patrick and Sch{\"o}ning, Michael Josef}, title = {Metabolic responses of Escherichia coli upon glucose pulses captured by a capacitive field-effect sensor}, series = {Physica Status Solidi (A)}, volume = {210}, journal = {Physica Status Solidi (A)}, number = {5}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0031-8965}, doi = {10.1002/pssa.201200900}, pages = {926 -- 931}, year = {2013}, abstract = {Living cells are complex biological systems transforming metabolites taken up from the surrounding medium. Monitoring the responses of such cells to certain substrate concentrations is a challenging task and offers possibilities to gain insight into the vitality of a community influenced by the growth environment. Cell-based sensors represent a promising platform for monitoring the metabolic activity and thus, the "welfare" of relevant organisms. In the present study, metabolic responses of the model bacterium Escherichia coli in suspension, layered onto a capacitive field-effect structure, were examined to pulses of glucose in the concentration range between 0.05 and 2 mM. It was found that acidification of the surrounding medium takes place immediately after glucose addition and follows Michaelis-Menten kinetic behavior as a function of the glucose concentration. In future, the presented setup can, therefore, be used to study substrate specificities on the enzymatic level and may as well be used to perform investigations of more complex metabolic responses. Conclusions and perspectives highlighting this system are discussed.}, language = {en} } @article{SiqueiraWernerBaeckeretal.2009, author = {Siqueira, Jose R. and Werner, Frederik and B{\"a}cker, Matthias and Poghossian, Arshak and Zucolotto, Valtencir and Oliveira, Osvaldo N. Jr. and Sch{\"o}ning, Michael Josef}, title = {Layer-by-Layer Assembly of Carbon Nanotubes Incorporated in Light-Addressable Potentiometric Sensors}, series = {Journal of Physical Chemistry C. 113 (2009), H. 33}, journal = {Journal of Physical Chemistry C. 113 (2009), H. 33}, publisher = {American Chemical Society}, address = {Washington, DC}, isbn = {1932-7455}, pages = {14765 -- 14770}, year = {2009}, language = {en} }