@article{PatzerKunzHuflageetal.2023, author = {Patzer, Theresa Sophie and Kunz, Andreas Steven and Huflage, Henner and Luetkens, Karsten Sebastian and Conrads, Nora and Gruschwitz, Philipp and Pannenbecker, Pauline and Erg{\"u}n, S{\"u}leyman and Bley, Thorsten Alexander and Grunz, Jan-Peter}, title = {Quantitative and qualitative image quality assessment in shoulder examinations with a first-generation photon-counting detector CT}, series = {Scientific Reports}, volume = {13}, journal = {Scientific Reports}, doi = {10.1038/s41598-023-35367-2}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-357925}, year = {2023}, abstract = {Photon-counting detector (PCD) CT allows for ultra-high-resolution (UHR) examinations of the shoulder without requiring an additional post-patient comb filter to narrow the detector aperture. This study was designed to compare the PCD performance with a high-end energy-integrating detector (EID) CT. Sixteen cadaveric shoulders were examined with both scanners using dose-matched 120 kVp acquisition protocols (low-dose/full-dose: CTDI\(_{vol}\) = 5.0/10.0 mGy). Specimens were scanned in UHR mode with the PCD-CT, whereas EID-CT examinations were conducted in accordance with the clinical standard as "non-UHR". Reconstruction of EID data employed the sharpest kernel available for standard-resolution scans (ρ\(_{50}\) = 12.3 lp/cm), while PCD data were reconstructed with both a comparable kernel (11.8 lp/cm) and a sharper dedicated bone kernel (16.5 lp/cm). Six radiologists with 2-9 years of experience in musculoskeletal imaging rated image quality subjectively. Interrater agreement was analyzed by calculation of the intraclass correlation coefficient in a two-way random effects model. Quantitative analyses comprised noise recording and calculating signal-to-noise ratios based on attenuation measurements in bone and soft tissue. Subjective image quality was higher in UHR-PCD-CT than in EID-CT and non-UHR-PCD-CT datasets (all p < 0.001). While low-dose UHR-PCD-CT was considered superior to full-dose non-UHR studies on either scanner (all p < 0.001), ratings of low-dose non-UHR-PCD-CT and full-dose EID-CT examinations did not differ (p > 0.99). Interrater reliability was moderate, indicated by a single measures intraclass correlation coefficient of 0.66 (95\% confidence interval: 0.58-0.73; p < 0.001). Image noise was lowest and signal-to-noise ratios were highest in non-UHR-PCD-CT reconstructions at either dose level (p < 0.001). This investigation demonstrates that superior depiction of trabecular microstructure and considerable denoising can be realized without additional radiation dose by employing a PCD for shoulder CT imaging. Allowing for UHR scans without dose penalty, PCD-CT appears as a promising alternative to EID-CT for shoulder trauma assessment in clinical routine.}, language = {en} } @article{ScorcellettiKaraZangeetal.2022, author = {Scorcelletti, Matteo and Kara, Serhan and Zange, Jochen and Jordan, Jens and Semler, Oliver and Sch{\"o}nau, Eckhard and Rittweger, J{\"o}rn and Ireland, Alex and Seefried, Lothar}, title = {Lower limb bone geometry in adult individuals with X-linked hypophosphatemia: an observational study}, series = {Osteoporosis International}, volume = {33}, journal = {Osteoporosis International}, number = {7}, doi = {10.1007/s00198-022-06385-z}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-324655}, pages = {1601-1611}, year = {2022}, abstract = {Summary We assessed lower-limb geometry in adults with X-linked hypophosphatemia (XLH) and controls. We found large differences in multiple measures including femoral and tibial torsion, bowing and cross-sectional area and acetabular version and coverage which may contribute to clinical problems such as osteoarthritis, fractures and altered gait common in XLH. Purpose Individuals with X-linked hypophosphatemia (XLH) are at risk of lower-limb deformities and early onset of osteoarthritis. These two factors may be linked, as altered biomechanics is a risk factor for osteoarthritis. This exploratory evaluation aims at providing clues and concepts for this association to facilitate future larger-scale and longitudinal studies on that aspect. Methods For this observational study, 13 patients with XLH, aged 18-65 years (6 female), were compared with sex-, age- and weight-matched healthy individuals at a single German research centre. Femoral and hip joint geometry, including femoral and tibial torsion and femoral and tibial shaft bowing, bone cross-sectional area (CSA) and acetabular version and coverage were measured from magnetic resonance imaging (MRI) scans. Results Total femoral torsion was 29° lower in individuals with XLH than in controls (p < 0.001), mainly resulting from lower intertrochanteric torsion (ITT) (p < 0.001). Femoral lateral and frontal bowing, tibial frontal bowing, mechanical axis, femoral mechanical-anatomical angle, acetabular version and acetabular coverage were all greater and tibial torsion lower in individuals with XLH as compared to controls (all p < 0.05). Greater femoral total and marrow cavity CSA, greater tibial marrow cavity CSA and lower cortical CSA were observed in XLH (all p < 0.05). Discussion We observed large differences in clinically relevant measures of tibia and particularly femur bone geometry in individuals with XLH compared to controls. These differences may plausibly contribute to clinical manifestations of XLH such as early-onset osteoarthritis, pseudofractures and altered gait and therefore should be considered when planning corrective surgeries.}, language = {en} } @article{StratosRinasSchroepferetal.2023, author = {Stratos, Ioannis and Rinas, Ingmar and Schr{\"o}pfer, Konrad and Hink, Katharina and Herlyn, Philipp and B{\"a}umler, Mario and Histing, Tina and Bruhn, Sven and M{\"u}ller-Hilke, Brigitte and Menger, Michael D. and Vollmar, Brigitte and Mittlmeier, Thomas}, title = {Effects on bone and muscle upon treadmill interval training in hypogonadal male rats}, series = {Biomedicines}, volume = {11}, journal = {Biomedicines}, number = {5}, issn = {2227-9059}, doi = {10.3390/biomedicines11051370}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-319266}, year = {2023}, abstract = {Testosterone deficiency in males is linked to various pathological conditions, including muscle and bone loss. This study evaluated the potential of different training modalities to counteract these losses in hypogonadal male rats. A total of 54 male Wistar rats underwent either castration (ORX, n = 18) or sham castration (n = 18), with 18 castrated rats engaging in uphill, level, or downhill interval treadmill training. Analyses were conducted at 4, 8, and 12 weeks postsurgery. Muscle force of the soleus muscle, muscle tissue samples, and bone characteristics were analyzed. No significant differences were observed in cortical bone characteristics. Castrated rats experienced decreased trabecular bone mineral density compared to sham-operated rats. However, 12 weeks of training increased trabecular bone mineral density, with no significant differences among groups. Muscle force measurements revealed decreased tetanic force in castrated rats at week 12, while uphill and downhill interval training restored force to sham group levels and led to muscle hypertrophy compared to ORX animals. Linear regression analyses showed a positive correlation between bone biomechanical characteristics and muscle force. The findings suggest that running exercise can prevent bone loss in osteoporosis, with similar bone restoration effects observed across different training modalities.}, language = {en} } @article{AltieriDiDatoModicaetal.2020, author = {Altieri, Barbara and Di Dato, Carla and Modica, Roberta and Bottiglieri, Filomena and Di Sarno, Antonella and Pittaway, James F.H. and Martini, Chiara and Faggiano, Antongiulio and Colao, Annamaria}, title = {Bone metabolism and vitamin D implication in gastroenteropancreatic neuroendocrine tumors}, series = {Nutrients}, volume = {12}, journal = {Nutrients}, number = {4}, issn = {2072-6643}, doi = {10.3390/nu12041021}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-203823}, year = {2020}, abstract = {Patients affected by gastroenteropancreatic-neuroendocrine tumors (GEP-NETs) have an increased risk of developing osteopenia and osteoporosis, as several factors impact on bone metabolism in these patients. In fact, besides the direct effect of bone metastasis, bone health can be affected by hormone hypersecretion (including serotonin, cortisol, and parathyroid hormone-related protein), specific microRNAs, nutritional status (which in turn could be affected by medical and surgical treatments), and vitamin D deficiency. In patients with multiple endocrine neoplasia type 1 (MEN1), a hereditary syndrome associated with NET occurrence, bone damage may carry other consequences. Osteoporosis may negatively impact on the quality of life of these patients and can increment the cost of medical care since these patients usually live with their disease for a long time. However, recommendations suggesting screening to assess bone health in GEP-NET patients are missing. The aim of this review is to critically analyze evidence on the mechanisms that could have a potential impact on bone health in patients affected by GEP-NET, focusing on vitamin D and its role in GEP-NET, as well as on factors associated with MEN1 that could have an impact on bone homeostasis.}, language = {en} } @article{HerrmannEngelkeEbertetal.2020, author = {Herrmann, Marietta and Engelke, Klaus and Ebert, Regina and M{\"u}ller-Deubert, Sigrid and Rudert, Maximilian and Ziouti, Fani and Jundt, Franziska and Felsenberg, Dieter and Jakob, Franz}, title = {Interactions between muscle and bone — Where physics meets biology}, series = {Biomolecules}, volume = {10}, journal = {Biomolecules}, number = {3}, issn = {2218-273X}, doi = {10.3390/biom10030432}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-203399}, year = {2020}, abstract = {Muscle and bone interact via physical forces and secreted osteokines and myokines. Physical forces are generated through gravity, locomotion, exercise, and external devices. Cells sense mechanical strain via adhesion molecules and translate it into biochemical responses, modulating the basic mechanisms of cellular biology such as lineage commitment, tissue formation, and maturation. This may result in the initiation of bone formation, muscle hypertrophy, and the enhanced production of extracellular matrix constituents, adhesion molecules, and cytoskeletal elements. Bone and muscle mass, resistance to strain, and the stiffness of matrix, cells, and tissues are enhanced, influencing fracture resistance and muscle power. This propagates a dynamic and continuous reciprocity of physicochemical interaction. Secreted growth and differentiation factors are important effectors of mutual interaction. The acute effects of exercise induce the secretion of exosomes with cargo molecules that are capable of mediating the endocrine effects between muscle, bone, and the organism. Long-term changes induce adaptations of the respective tissue secretome that maintain adequate homeostatic conditions. Lessons from unloading, microgravity, and disuse teach us that gratuitous tissue is removed or reorganized while immobility and inflammation trigger muscle and bone marrow fatty infiltration and propagate degenerative diseases such as sarcopenia and osteoporosis. Ongoing research will certainly find new therapeutic targets for prevention and treatment.}, language = {en} } @article{PaudelFusiSchmidt2021, author = {Paudel, Rupesh and Fusi, Lorenza and Schmidt, Marc}, title = {The MEK5/ERK5 pathway in health and disease}, series = {International Journal of Molecular Sciences}, volume = {22}, journal = {International Journal of Molecular Sciences}, number = {14}, issn = {1422-0067}, doi = {10.3390/ijms22147594}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-261638}, year = {2021}, abstract = {The MEK5/ERK5 mitogen-activated protein kinases (MAPK) cascade is a unique signaling module activated by both mitogens and stress stimuli, including cytokines, fluid shear stress, high osmolarity, and oxidative stress. Physiologically, it is mainly known as a mechanoreceptive pathway in the endothelium, where it transduces the various vasoprotective effects of laminar blood flow. However, it also maintains integrity in other tissues exposed to mechanical stress, including bone, cartilage, and muscle, where it exerts a key function as a survival and differentiation pathway. Beyond its diverse physiological roles, the MEK5/ERK5 pathway has also been implicated in various diseases, including cancer, where it has recently emerged as a major escape route, sustaining tumor cell survival and proliferation under drug stress. In addition, MEK5/ERK5 dysfunction may foster cardiovascular diseases such as atherosclerosis. Here, we highlight the importance of the MEK5/ERK5 pathway in health and disease, focusing on its role as a protective cascade in mechanical stress-exposed healthy tissues and its function as a therapy resistance pathway in cancers. We discuss the perspective of targeting this cascade for cancer treatment and weigh its chances and potential risks when considering its emerging role as a protective stress response pathway.}, language = {en} } @article{PereiraTrivanovićHerrmann2019, author = {Pereira, A. R. and Trivanović, D. and Herrmann, M.}, title = {Approaches to mimic the complexity of the skeletal mesenchymal stem/stromal cell niche in vitro}, series = {European Cells and Materials}, volume = {37}, journal = {European Cells and Materials}, issn = {1473-2262}, doi = {10.22203/eCM.v037a07}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-268823}, pages = {88-112}, year = {2019}, abstract = {Mesenchymal stem/stromal cells (MSCs) are an essential element of most modern tissue engineering and regenerative medicine approaches due to their multipotency and immunoregulatory functions. Despite the prospective value of MSCs for the clinics, the stem cells community is questioning their developmental origin, in vivo localization, identification, and regenerative potential after several years of far-reaching research in the field. Although several major progresses have been made in mimicking the complexity of the MSC niche in vitro, there is need for comprehensive studies of fundamental mechanisms triggered by microenvironmental cues before moving to regenerative medicine cell therapy applications. The present comprehensive review extensively discusses the microenvironmental cues that influence MSC phenotype and function in health and disease - including cellular, chemical and physical interactions. The most recent and relevant illustrative examples of novel bioengineering approaches to mimic biological, chemical, and mechanical microenvironmental signals present in the native MSC niche are summarized, with special emphasis on the forefront techniques to achieve bio-chemical complexity and dynamic cultures. In particular, the skeletal MSC niche and applications focusing on the bone regenerative potential of MSC are addressed. The aim of the review was to recognize the limitations of the current MSC niche in vitro models and to identify potential opportunities to fill the bridge between fundamental science and clinical application of MSCs.}, language = {en} } @article{FuchsHeiligMcDonoghetal.2020, author = {Fuchs, Konrad F. and Heilig, Philipp and McDonogh, Miriam and Boelch, Sebastian and Gbureck, Uwe and Meffert, Rainer H. and Hoelscher-Doht, Stefanie and Jordan, Martin C.}, title = {Cement-augmented screw fixation for calcaneal fracture treatment: a biomechanical study comparing two injectable bone substitutes}, series = {Journal of Orthopaedic Surgery and Research}, volume = {15}, journal = {Journal of Orthopaedic Surgery and Research}, doi = {10.1186/s13018-020-02009-6}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-230336}, year = {2020}, abstract = {Background The role of cement-augmented screw fixation for calcaneal fracture treatment remains unclear. Therefore, this study was performed to biomechanically analyze screw osteosynthesis by reinforcement with either a calcium phosphate (CP)-based or polymethylmethacrylate (PMMA)-based injectable bone cement. Methods A calcaneal fracture (Sanders type IIA) including a central cancellous bone defect was generated in 27 synthetic bones, and the specimens were assigned to 3 groups. The first group was fixed with four screws (3.5 mm and 6.5 mm), the second group with screws and CP-based cement (Graftys (R) QuickSet; Graftys, Aix-en-Provence, France), and the third group with screws and PMMA-based cement (Traumacem (TM) V+; DePuy Synthes, Warsaw, IN, USA). Biomechanical testing was conducted to analyze peak-to-peak displacement, total displacement, and stiffness in following a standardized protocol. Results The peak-to-peak displacement under a 200-N load was not significantly different among the groups; however, peak-to-peak displacement under a 600- and 1000-N load as well as total displacement exhibited better stability in PMMA-augmented screw osteosynthesis compared to screw fixation without augmentation. The stiffness of the construct was increased by both CP- and PMMA-based cements. Conclusion Addition of an injectable bone cement to screw osteosynthesis is able to increase fixation strength in a biomechanical calcaneal fracture model with synthetic bones. In such cases, PMMA-based cements are more effective than CP-based cements because of their inherently higher compressive strength. However, whether this high strength is required in the clinical setting for early weight-bearing remains controversial, and the non-degradable properties of PMMA might cause difficulties during subsequent interventions in younger patients.}, language = {en} } @phdthesis{Koschitzki2020, author = {Koschitzki, Kim Christine Cornelia}, title = {Evaluation of preclinical animal models in bone tissue engineering and their success in clinical translation}, doi = {10.25972/OPUS-20759}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-207593}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2020}, abstract = {Autologous bone still represents today's gold standard for the treatment of critical size bone defects and fracture non-unions despite associated disadvantages regarding limitations in availability, donor site morbidity, costs and efficacy. Bone tissue engineered constructs would present a promising alternative to currently available treatments. However, research on preclinical animal studies still fails to provide clinical applicable results able to allow the replacement of currently applied methods. It seems that the idea of bone tissue engineering, which has now been integral part of academic studies for over 30 years, got somehow stuck at an intermediate level, in between intense preclinical research and striven stages of initial clinical trial phases. A clear discrepancy exists between the number of studies with preclinical animal models for bone tissue engineering and the number of clinically approved bone tissue engineered constructs available to patients. The aim of this thesis was hence to evaluate preclinical animal models for bone tissue engineering as well as the perception of scientists and clinicians towards these models. Moreover, the general role of bone tissue engineering and its clinical need assessed by scientists and surgeons was investigated. A survey was conducted questioning both scientific and clinical opinions on currently available study designs and researchers' satisfaction with preclinical animal models. Additionally, a literature research was conducted, resulting in 167 papers from the last 10 years that report current designs of preclinical orthotopic animal studies in bone tissue engineering. Thereby, the focus lied on the description of the models regarding animal species, strain, age, gender and defect design. The outcome of the literature search was evaluated and compared to the outcome obtained from the survey. The survey data revealed that both scientists and surgeons generally remain positive about the future role of bone tissue engineering and its step to clinical translation, at least in the distant future, where it then might replace the current gold standard, autologous bone. Moreover, most of the participants considered preclinical animal models as relevant and well developed but the results as not yet realizable in the clinics. Surgeons thereby demonstrated a slightly more optimistic perception of currently conducted research with animal models compared to scientists. However, a rather inconsistent description of present preclinical study designs could be discerned when evaluating the reported study designs in the survey and the papers of the literature search. Indeed, defining an appropriate animal species, strain, age, gender, observation time, observation method and surgical design often depends on different indications and research questions and represents a highly challenging task for the establishment of a preclinical animal model. The existing lack of valid guidelines for preclinical testing of bone tissue engineering leads hence to a lack of well standardized preclinical animal models. Moreover, still existing knowledge gaps regarding aspects that affect the process of fracture healing, such as vascularization or immunological aspects, were found to hinder clinical translation of bone tissue engineered constructs. Using literature review and survey, this thesis points out critical issues that need to be addressed to allow clinical translation of bone tissue engineered constructs. It can be concluded that currently existing study designs with preclinical animal models cannot live up to the claim of providing suitable results for clinical implementation. The here presented comprehensive summary of currently used preclinical animal models for bone tissue engineering reveals a missing consensus on the usage of models such as an apparent lack of reporting and standardization regarding the study designs described in both papers from the literature review and the survey. It thereby indicates a crucial need to improve preclinical animal models in order to allow clinical translation. Despite the fact that participants of the survey generally revealed a positive perception towards the use of bone tissue engineered constructs and affirmed the clinical need for such novel designs, the missing standardization constitutes a main weak point for the provision of reliable study outcome and the translational success of the models. The optimization of reproducibility and reliability, as well as the further understanding of ongoing mechanisms in bone healing in order to develop effective tissue engineered constructs, need to form the basis of all study designs. The study outcomes might then fulfill the requirements of maybe today's and hopefully tomorrow's aging population.}, language = {en} } @article{KollmannsbergerKerschnitzkiReppetal.2017, author = {Kollmannsberger, Philip and Kerschnitzki, Michael and Repp, Felix and Wagermaier, Wolfgang and Weinkamer, Richard and Fratzl, Peter}, title = {The small world of osteocytes: connectomics of the lacuno-canalicular network in bone}, series = {New Journal of Physics}, volume = {19}, journal = {New Journal of Physics}, number = {073019}, doi = {10.1088/1367-2630/aa764b}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-170662}, year = {2017}, abstract = {Osteocytes and their cell processes reside in a large, interconnected network of voids pervading the mineralized bone matrix of most vertebrates. This osteocyte lacuno-canalicular network (OLCN) is believed to play important roles in mechanosensing, mineral homeostasis, and for the mechanical properties of bone. While the extracellular matrix structure of bone is extensively studied on ultrastructural and macroscopic scales, there is a lack of quantitative knowledge on how the cellular network is organized. Using a recently introduced imaging and quantification approach, we analyze the OLCN in different bone types from mouse and sheep that exhibit different degrees of structural organization not only of the cell network but also of the fibrous matrix deposited by the cells. We define a number of robust, quantitative measures that are derived from the theory of complex networks. These measures enable us to gain insights into how efficient the network is organized with regard to intercellular transport and communication. Our analysis shows that the cell network in regularly organized, slow-growing bone tissue from sheep is less connected, but more efficiently organized compared to irregular and fast-growing bone tissue from mice. On the level of statistical topological properties (edges per node, edge length and degree distribution), both network types are indistinguishable, highlighting that despite pronounced differences at the tissue level, the topological architecture of the osteocyte canalicular network at the subcellular level may be independent of species and bone type. Our results suggest a universal mechanism underlying the self-organization of individual cells into a large, interconnected network during bone formation and mineralization.}, language = {en} }