[Clavicle fractures: practical approach in clinical routine]. / Klavikulafrakturen ­ praktisches Vorgehen im klinischen Alltag.

Fractures of the clavicle are among the most common fractures. They typically result from a fall onto the lateral shoulder or the extended arm and are often related to sports and bicycle accidents. Obtaining the exact trauma mechanism, proper clinical findings and adequate X­rays usually lead to the correct diagnosis. Non-displacement fractures can be treated conservatively with good results. Unstable and displaced fractures should be treated operatively. Open fractures or looming penetration are emergencies und should be treated immediately. In addition to fracture classification and morphology, other factors such as additional injuries and patient-related factors need to be considered in order to make an individualized therapy decision. In operative treatment, angular stable plating is the therapy of choice, and in most cases early functional aftercare is possible.

Minimal-invasive anterior approach to the hip provides a better surgery-related and early postoperative functional outcome than conventional lateral approach after hip hemiarthroplasty following femoral neck fractures.

INTRODUCTION: Femoral neck fractures (FNF) are one of the most frequent fractures among elderly patients and commonly require surgical treatment. Bipolar hip hemiarthroplasty (BHHA) is mostly performed in these cases. MATERIAL AND METHODS: In the present retrospective study geriatric patients with FNF (n = 100) treated either by anterior minimal-invasive surgery (AMIS; n = 50) or lateral conventional surgery (LCS; n = 50) were characterized (age at the time of surgery, sex, health status/ASA score, walking distance and need for walking aids before the injury) and intraoperative parameters (duration of surgery, blood loss, complications), as well as postoperative functional performance early (duration of in-patient stay, radiological leg length discrepancy, ability to full weight-bearing, mobilization with walking aids) and 12 months (radiological signs of sintering, clinical parameters, complication rate) after surgery were analyzed. RESULTS: Patients in the AMIS group demonstrated a reduced blood loss intraoperatively, while the duration of surgery and complication rates did not differ between the two groups. Further, more patients in the AMIS group achieved full weight-bearing of the injured leg and were able to walk with a rollator or less support during their in-patient stay. Of interest, patients in the AMIS group achieved this level of mobility earlier than those of the LCS group, although their walking distance before the acute injury was reduced. Moreover, patients of the AMIS group showed equal leg lengths postoperatively more often than patients of the LCS group. No significant differences in functional and surgery-related performance could be observed between AMIS and LCS group at 12 months postoperatively. CONCLUSIONS: In conclusion, geriatric patients treated by AMIS experience less surgery-related strain and recover faster in the early postoperative phase compared to LCS after displaced FNF. Hence, AMIS should be recommended for BHHA in these vulnerable patients.

[Management of complications of acetabular fractures]. / Management der Komplikationen von Acetabulumfrakturen.

Surgical treatment of acetabular fractures represents a special challenge in the field of trauma surgery. Complications are mostly due to the trauma itself or are iatrogenic. The handling and strategy to overcome complications in acetabular surgery are oriented towards the type of complication and the time of occurrence. Generally, a differentiation is made between early perioperative complications and late complications. The present article describes the most frequent complications during the surgical treatment of acetabular fractures, discusses the various treatment options based on individual case examples and gives differentiated recommendations to overcome the complications. The treatment concept should initially comprise a comprehensive primary prophylaxis to prevent complications. In cases of early perioperative complications, e.g. postoperative wound infections, hemorrhage or incorrect implant positioning, rapid and systematic surgical revision should be performed. In contrast, the treatment of late complications (e.g. implant associated failures, secondary osteoarthrosis of the hip, periarticular heterotopic ossification, non-unions and late infections) depends on the clinical and functional condition of the patient. In symptomatic elderly patients secondary total hip replacement is usually a valid option, whereas younger patients with late complications can be candidates for joint-preserving procedures. The management of complications in acetabular surgery regularly requires intense patient guidance as well as thorough clarification and should be performed in specialized centers.

Locking Nail versus Plate Fixation in Calcaneal Fractures: Brief report on a Retrospective Analysis of Treatment Characteristics and Radiographic Correction Potential.

PURPOSE OF THE STUDY Minimal and limited access techniques are gaining increasing interest for the treatment of displaced intra-articular calcaneal fractures. The ideal treatment method is however still debated and largely based on individual case factors and surgeon experience. Aim of this study was thus to compare the treatment characteristics and radiographic correction potential of a locking nail system with a sinus tarsi approach to plate fixation via an extended lateral approach. MATERIAL AND METHODS We retrospectively reviewed 39 cases of patients with calcaneal fractures that received primary fracture treatment for displaced intra-articular calcaneal fractures between July 2017 and March 2020. Patient characteristics, time to surgery, time to discharge, OR time and the correction achieved were analyzed and comparative statistics performed. RESULTS In total 19 patients treated with the locking nail and 20 patients treated with plate fixation were analyzed. Patient age and fracture severity according to the Sanders classification were comparable between the groups. Overall surgical time, as well as the achieved reduction was equal between both groups. Time to surgery, as well as time from surgery to discharge was significantly shorter in the locking nail group. 2 additional soft tissue procedures were necessary in the extended lateral approach group. DISCUSSION AND CONCLUSIONS The results with the locking calcaneus nail and sinus tarsi approach suggest, that similar treatment results can be achieved as with plate osteosynthesis and an extended lateral approach. Soft tissue management, as well as pre- and postoperative timing and discharge management can be improved with the nail. Further controlled trials comparing the longterm outcome between the treatment options are needed. Key words: calcaneus fracture, sinus tarsi approach, calcaneal nail, C-Nail.

Weight-Bearing Restrictions after Acetabular Fracture, Necessity or False Hope? A Brief Observational Study.

PURPOSE OF THE STUDY Most common postoperative treatment recommendations after acetabulum fractures suggest at least 6 weeks of postoperative partial or non weight-bearing. To protect the osteosynthetic construct this surgically set weight-bearing limit is trained by physical therapy. Aim of our analysis was to determine the free field patient compliance to these weight-bearing restrictions and observe their influence on the early postoperative radiographic imaging. MATERIAL AND METHODS Patients after surgical treatment of an acetabulum fracture were included in our analysis. Every patient was instructed to maintain a 20 kg weight-bearing limit for 6 weeks. Postoperative weight-bearing was continuously monitored during this time with a pressure measuring insole. Maximum weight-bearing per day was recorded and maintenance of reduction assessed after this time. RESULTS In total 10 patients were included into the study. Only 1 patient stayed within the weight-bearing limit during the analysis. Maximum weight-bearing as high as 110 kg was recorded. All patients maintained postoperative reduction at the 6 week timepoint. DISCUSSION AND CONCLUSIONS Despite regular physical therapy training compliance to the generally accepted weight-bearing limits was low. Regardless of the non-compliance the radiographic outcome remained unchanged. Further analysis on the use of permissive weightbearing aftercare regimes are warranted. Key words: weight-bearing, acetabulum fracture, compliance.

Local Application of Mineral-Coated Microparticles Loaded With VEGF and BMP-2 Induces the Healing of Murine Atrophic Non-Unions.

Deficient angiogenesis and disturbed osteogenesis are key factors for the development of nonunions. Mineral-coated microparticles (MCM) represent a sophisticated carrier system for the delivery of vascular endothelial growth factor (VEGF) and bone morphogenetic protein (BMP)-2. In this study, we investigated whether a combination of VEGF- and BMP-2-loaded MCM (MCM + VB) with a ratio of 1:2 improves bone repair in non-unions. For this purpose, we applied MCM + VB or unloaded MCM in a murine non-union model and studied the process of bone healing by means of radiological, biomechanical, histomorphometric, immunohistochemical and Western blot techniques after 14 and 70 days. MCM-free non-unions served as controls. Bone defects treated with MCM + VB exhibited osseous bridging, an improved biomechanical stiffness, an increased bone volume within the callus including ongoing mineralization, increased vascularization, and a histologically larger total periosteal callus area consisting predominantly of osseous tissue when compared to defects of the other groups. Western blot analyses on day 14 revealed a higher expression of osteoprotegerin (OPG) and vice versa reduced expression of receptor activator of NF-κB ligand (RANKL) in bone defects treated with MCM + VB. On day 70, these defects exhibited an increased expression of erythropoietin (EPO), EPO-receptor and BMP-4. These findings indicate that the use of MCM for spatiotemporal controlled delivery of VEGF and BMP-2 shows great potential to improve bone healing in atrophic non-unions by promoting angiogenesis and osteogenesis as well as reducing early osteoclast activity.

Erythropoietin does not improve fracture healing in aged mice.

Fracture healing in the elderly is associated with a declined healing potential caused by multiple factors including a delay of vascularization. Erythropoietin (EPO) has been demonstrated to improve vascularization and fracture healing in adult mice. We, therefore, hypothesized that EPO in aged mice also improves fracture healing. For this purpose, EPO was given daily in a femoral fracture model in aged mice and compared to vehicle-treated controls using radiological, biomechanical, histomorphometric and Western blot techniques. Blood analyses revealed significantly higher concentrations of hemoglobin and a higher hematocrit in EPO-treated animals at 14 and 35 days after fracture. Micro-computed tomography (µCT) indicated that the fraction of bone volume/tissue volume within the callus did not differ between the two groups. However, µCT showed a 3-fold increased tissue mineral density (TMD) in the callus of EPO-treated animals compared to controls. The callus TMD of the EPO-treated animals was also 2-fold higher when compared to the TMD of the unfractured contralateral femur. Interestingly, biomechanical analyses revealed a reduced bending stiffness in femurs of EPO-treated animals at day 35. The histomorphometrically analyzed callus size and callus composition did not show significant differences between the study groups. However, Western blot analyses exhibited an increased expression of osteoprotegerin (OPG), but in particular of receptor activator of NF-κB ligand (RANKL) in the callus of the EPO-treated animals. Further histological analyses of the callus tissue showed that this was associated with an increased number of newly formed blood vessels and a higher number of tartrate-resistant acid phosphatase (TRAP)+ cells. Conclusion: In fracture healing of aged mice EPO treatment increases callus TMD as well as OPG and RANKL expression, indicating an accelerated bone turnover when compared to controls. However, EPO does not improve fracture healing in aged mice. The process of fracture healing may be altered by EPO due to a deterioration of the microcirculation caused by the worsened rheological properties of the blood and due to an increased bone fragility caused by the accelerated bone turnover. Thus, EPO may not be used to improve fracture healing in the elderly.

Effects of locally applied adipose tissue-derived microvascular fragments by thermoresponsive hydrogel on bone healing.

Insufficient vascularization is a major cause for the development of non-unions. To overcome this problem, adipose tissue-derived microvascular fragments (MVF) may serve as vascularization units. However, their application into bone defects needs a carrier system. Herein, we analyzed whether this is achieved by a thermoresponsive hydrogel (TRH). MVF were isolated from CD-1 mice and cultivated after incorporation into TRH, while non-incorporated MVF served as controls. Viability of MVF was assessed immunohistochemically over a 7-day period. Moreover, osteotomies were induced in femurs of CD-1 mice. The osteotomy gaps were filled with MVF-loaded TRH (TRH + MVF), unloaded TRH (TRH) or no material (control). Bone healing was evaluated 14 and 35 days postoperatively. MVF incorporated into TRH exhibited less apoptotic cells and showed a stable vessel morphology compared to controls. Micro-computed tomography revealed a reduced bone volume in TRH + MVF femurs. Histomorphometry showed less bone and more fibrous tissue after 35 days in TRH + MVF femurs compared to controls. Accordingly, TRH + MVF femurs exhibited a lower osseous bridging score and a reduced bending stiffness. Histology and Western blot analysis revealed an increased vascularization and CD31 expression, whereas vascular endothelial growth factor (VEGF) expression was reduced in TRH + MVF femurs. Furthermore, the callus of TRH + MVF femurs showed increased receptor activator of NF-κB ligand expression and higher numbers of osteoclasts. These findings indicate that TRH is an appropriate carrier system for MVF. Application of TRH + MVF increases the vascularization of bone defects. However, this impairs bone healing, most likely due to lower VEGF expression during the early course of bone healing. STATEMENT OF SIGNIFICANCE: In the present study we analyzed for the first time the in vivo performance of a thermoresponsive hydrogel (TRH) as a delivery system for bioactive microvascular fragments (MVF). We found that TRH represents an appropriate carrier for MVF as vascularization units and maintains their viability. Application of MVF-loaded TRH impaired bone formation in an established murine model of bone healing, although vascularization was improved. This unexpected outcome was most likely due to a reduced VEGF expression in the early phase bone healing.

[A new continuous gait analysis system for ankle fracture aftercare]. / Ein neues, kontinuierliches Ganganalysesystem zur Nachbehandlung von Sprunggelenkfrakturen.

BACKGROUND: Correct aftercare following lower extremity fractures remains a controversial issue. Reliable, clinically applicable weight-bearing recommendations have not yet been defined. The aim of the current study was to establish a new gait analysis insole during physical therapy aftercare of ankle fractures to test patients' continuous, long-term compliance to partial weight-bearing restrictions and investigate whether patients can estimate their weight-bearing compliance. MATERIALS AND METHODS: The postoperative gait of 14 patients after operative treatment of Weber B-type ankle fractures was monitored continuously for six weeks (OpenGO, Moticon GmbH, Munich). All patients were instructed and trained by physical therapists on how to maintain partial weight-bearing for this time. Discontinuous (three, six and twelve weeks) clinical (patient questionnaire, visual analogue pain score [VAS]) and radiographic controls were performed. RESULTS: Despite the set weight-bearing limits, individual ranges for overall weight-bearing (range 5-107% of the contralateral side) and patient activity (range 0-366 min/day) could be shown. A good correlation between weight-bearing and pain was seen (rs = -0.68; p = <0.0001). Patients significantly underestimated their weight-bearing time over the set limit (2.3 ± 1.4 min/day vs. real: 12.6 ± 5.9 min/day; p < 0.01). CONCLUSIONS: Standardized aftercare protocols and repeated training alone cannot ensure compliance to postoperative partial weight-bearing. Patients unconsciously increased weight-bearing based on their pain level. This study shows that new, individual and possibly technology-assisted weight-bearing regimes are needed. The introduced measuring device is feasible to monitor and steer patient weight-bearing during future studies.

Taxane-mediated radiosensitization derives from chromosomal missegregation on tripolar mitotic spindles orchestrated by AURKA and TPX2.

Taxane-based radiochemotherapy is a central treatment option for various cancer entities in locally advanced stages. The therapeutic synergism of this combined modality approach due to taxane-mediated radiosensitization of cancer cells is well-known. However, the underlying molecular mechanisms remain largely elusive, and mechanism-derived predictive markers of taxane-based radiochemotherapy are currently not available. Here, we show that clinically relevant doses of Paclitaxel, the prototype taxane, stimulate a tripolar mode of mitosis leading to chromosomal missegregation and aneuploidization rather than interfering with cell cycle progression. This distinct mitotic phenotype was interlinked with Paclitaxel-mediated radiosensitization via overexpression of mitotic Aurora kinase A (AURKA) and its cofactor TPX2 whose knockdown rescued the bipolar mode of cell division and largely attenuated the radiosensitizing effects of Paclitaxel. In the cancer genome atlas (TCGA) lung adenocarcinoma cohort, high expression levels of AURKA and TPX2 were associated with specifically improved overall survival upon taxane-based radiochemotherapy, but not in case of non-taxane-based radiochemotherapy, chemo- or radiotherapy only. Thus, our data provide insights into Paclitaxel-mediated radiosensitization on a mechanistic and molecular level and identify AURKA and TPX2 as the first potential mechanism-based, predictive markers of taxane-based radiochemotherapy.

Influence of age and housing systems on properties of tibia and humerus of Lohmann White hens1: Bone properties of laying hens in commercial housing systems.

This study was aimed at analyzing bone properties of Lohmann White hens in different commercial housing systems at various points throughout production. Pullets reared in conventional cages (CC) were either continued in CC or moved to enriched colony cages (EN) at 19 weeks. Pullets reared in cage-free aviaries (AV) were moved to AV hen houses. Bone samples were collected from 60 hens at each of 18 and 72 wk and 30 hens at 26 and 56 wk from each housing system. Left tibiae and humeri were broken under uniform bending to analyze mechanical properties. Cortical geometry was analyzed using digital calipers at the fracture site. Contralateral tibiae and humeri were used for measurement of ash percentage. AV pullets' humeri had 41% greater cortical areas, and tibiae had 19% greater cortical areas than the CC pullets (P < 0.05). Average humeri diameter was greater in AV pullets than in CC pullets (P < 0.05), whereas the tibiae outer dimensions were similar. Aviary pullet bones had greater stiffness (31 and 7% greater for tibiae and humeri, respectively) and second moment of inertia (43 and 13% greater for tibiae and humeri, respectively) than CC pullets (P < 0.05). The differences between bones of AV and CC hens persisted throughout the laying cycle. Moving CC pullets to EN resulted in decreased endosteal resorption in humeri, evident by a 7.5% greater cortical area in the EN hens (P < 0.05). Whole-bone breaking strength did not change with age. Stiffness increased with age, while energy to failure decreased in both the tibiae and humeri. These results indicated that tibiae and humeri of laying hens become stiffer but lose toughness and become brittle with age. Furthermore, AV and EN systems can bring positive changes in mechanical and structural properties that are more pronounced in the humerus than the tibia.

The reliability of commonly used electrophysiology measures.

BACKGROUND: Electrophysiological measures can help understand brain function both in healthy individuals and in the context of a disease. Given the amount of information that can be extracted from these measures and their frequent use, it is essential to know more about their inherent reliability. OBJECTIVE/HYPOTHESIS: To understand the reliability of electrophysiology measures in healthy individuals. We hypothesized that measures of threshold and latency would be the most reliable and least susceptible to methodological differences between study sites. METHODS: Somatosensory evoked potentials from 112 control participants; long-latency reflexes, transcranial magnetic stimulation with resting and active motor thresholds, motor evoked potential latencies, input/output curves, and short-latency sensory afferent inhibition and facilitation from 84 controls were collected at 3 visits over 24 months at 4 Track-On HD study sites. Reliability was assessed using intra-class correlation coefficients for absolute agreement, and the effects of reliability on statistical power are demonstrated for different sample sizes and study designs. RESULTS: Measures quantifying latencies, thresholds, and evoked responses at high stimulator intensities had the highest reliability, and required the smallest sample sizes to adequately power a study. Very few between-site differences were detected. CONCLUSIONS: Reliability and susceptibility to between-site differences should be evaluated for electrophysiological measures before including them in study designs. Levels of reliability vary substantially across electrophysiological measures, though there are few between-site differences. To address this, reliability should be used in conjunction with theoretical calculations to inform sample size and ensure studies are adequately powered to detect true change in measures of interest.

White matter predicts functional connectivity in premanifest Huntington's disease.

OBJECTIVES: The distribution of pathology in neurodegenerative disease can be predicted by the organizational characteristics of white matter in healthy brains. However, we have very little evidence for the impact these pathological changes have on brain function. Understanding any such link between structure and function is critical for understanding how underlying brain pathology influences the progressive behavioral changes associated with neurodegeneration. Here, we demonstrate such a link between structure and function in individuals with premanifest Huntington's. METHODS: Using diffusion tractography and resting state functional magnetic resonance imaging to characterize white matter organization and functional connectivity, we investigate whether characteristic patterns of white matter organization in the healthy human brain shape the changes in functional coupling between brain regions in premanifest Huntington's disease. RESULTS: We find changes in functional connectivity in premanifest Huntington's disease that link directly to underlying patterns of white matter organization in healthy brains. Specifically, brain areas with strong structural connectivity show decreases in functional connectivity in premanifest Huntington's disease relative to controls, while regions with weak structural connectivity show increases in functional connectivity. Furthermore, we identify a pattern of dissociation in the strongest functional connections between anterior and posterior brain regions such that anterior functional connectivity increases in strength in premanifest Huntington's disease, while posterior functional connectivity decreases. INTERPRETATION: Our findings demonstrate that organizational principles of white matter underlie changes in functional connectivity in premanifest Huntington's disease. Furthermore, we demonstrate functional antero-posterior dissociation that is in keeping with the caudo-rostral gradient of striatal pathology in HD.

BMP-2-coated mineral coated microparticles improve bone repair in atrophic non-unions.

Atrophic non-unions are a major clinical problem. Mineral coated microparticles (MCM) are electrolyte-coated hydroxyapatite particles that have been shown in vitro to bind growth factors electrostatically and enable a tuneable sustained release. Herein, we studied whether MCM can be used in vivo to apply Bone Morphogenetic Protein-2 (BMP-2) to improve bone repair of atrophic non-unions. For this purpose, atrophic non-unions were induced in femurs of CD-1 mice (n = 48). Animals either received BMP-2-coated MCM (MCM + BMP; n = 16), uncoated MCM (MCM; n = 16) or no MCM (NONE; n = 16). Bone healing was evaluated 2 and 10 weeks postoperatively by micro-computed tomographic (µCT), biomechanical, histomorphometric and immunohistochemical analyses. µCT revealed more bone volume with more highly mineralised bone in MCM + BMP femurs. Femurs of MCM + BMP animals showed a significantly higher bending stiffness compared to other groups. Histomorphometry further demonstrated that the callus of MCM + BMP femurs was larger and contained more bone and less fibrous tissue. After 10 weeks, 7 of 8 MCM + BMP femurs presented with complete osseous bridging, whereas NONE femurs exhibited a non-union rate of 100 %. Of interest, immunohistochemistry could not detect macrophages within the callus, indicating a good biocompatibility of MCM. In conclusion, the local application of BMP-2-coated MCM improved bone healing in a challenging murine non-union model and, thus, should be of clinical interest in the treatment of non-unions.

Neuropsychological and neuroimaging underpinnings of schizoaffective disorder: a systematic review.

OBJECTIVES: The neurobiological basis and nosological status of schizoaffective disorder remains elusive and controversial. This study provides a systematic review of neurocognitive and neuroimaging findings in the disorder. METHODS: A comprehensive literature search was conducted via PubMed, ScienceDirect, Scopus and Web of Knowledge (from 1949 to 31st March 2015) using the keyword 'schizoaffective disorder' and any of the following terms: 'neuropsychology', 'cognition', 'structural neuroimaging', 'functional neuroimaging', 'multimodal', 'DTI' and 'VBM'. Only studies that explicitly examined a well defined sample, or subsample, of patients with schizoaffective disorder were included. RESULTS: Twenty-two of 43 neuropsychological and 19 of 51 neuroimaging articles fulfilled inclusion criteria. We found a general trend towards schizophrenia and schizoaffective disorder being related to worse cognitive performance than bipolar disorder. Grey matter volume loss in schizoaffective disorder is also more comparable to schizophrenia than to bipolar disorder which seems consistent across further neuroimaging techniques. CONCLUSIONS: Neurocognitive and neuroimaging abnormalities in schizoaffective disorder resemble more schizophrenia than bipolar disorder. This is suggestive for schizoaffective disorder being a subtype of schizophrenia or being part of the continuum spectrum model of psychosis, with schizoaffective disorder being more skewed towards schizophrenia than bipolar disorder.

Eukaryotic initiation factor 4E-binding protein 1 (4E-BP1): a master regulator of mRNA translation involved in tumorigenesis.

Protein synthesis activity is abnormally enhanced in cancer cells to support their uncontrolled growth. However, this process needs to be tightly restricted under metabolic stress-a condition often found within the tumor microenvironment-to preserve cell viability. mTORC1 is critical to link protein synthesis activity to nutrient and oxygen levels, in part by controlling the 4E-BP1-eIF4E axis. Whereas mTORC1 and eIF4E are known pro-tumorigenic factors, whose expression or activity is increased in numerous cancers, the role of 4E-BP1 in cancer is not yet definitive. On the one hand, 4E-BP1 has tumor suppressor activity by inhibiting eIF4E and, thus, blocking mRNA translation and proliferation. This is corroborated by elevated levels of phosphorylated and hence inactive 4E-BP1, which are detected in various cancers. On the other hand, 4E-BP1 has pro-tumorigenic functions as it promotes tumor adaptation to metabolic and genotoxic stress by selectively enhancing or preventing the translation of specific transcripts. Here we describe the molecular and cellular functions of 4E-BP1 and highlight the distinct roles of 4E-BP1 in cancer depending on the microenvironmental context of the tumor.

Housing conditions alter properties of the tibia and humerus during the laying phase in Lohmann white Leghorn hens.

Osteoporosis in caged hens is one driving factor for the United States egg industry to explore options regarding alternative housing systems for laying hens. The aim of our research was to study the influence of housing systems on tibiae and humeri of 77-week-old Lohmann White hens. Pullets raised in an aviary system were either continued in aviary hen systems (AV) or conventional cages (AC) whereas pullets reared in conventional cages continued in conventional hen cages (CC) or enriched colony cages (EN) at 19 weeks. From each group, 120 hens were randomly euthanized and right and left tibae and humeri were excised for structural and mechanical analysis. Volumetric density of the cortical bone was measured using quantitative computed tomography (QCT). Aviary (AV) hens had greater cortical thickness and density but similar outer dimensions to AC hens (P < 0.05). Hens in EN system had humeri with similar cortical thickness and density but wider outer dimensions than the humeri of CC hens (P < 0.05). Cortical geometry of the tibiae was the same for the EN and CC hens, whereas EN hens had denser tibial cortex than CC hens (P < 0.05). Geometrical changes in the humeri suggest that hens in the AV system were better able to protect their structure from endosteal resorption during the laying phase. Humeri of AV and EN hens had increased second moment of area compared to the AC and CC hens; however, the changes were not observed in tibiae. Mechanical property differences were observed, with bones of AV hens having greater failure moment and stiffness than AC hens and the same difference was observed between the EN and CC hens, (P < 0.05). These findings indicate that movement limitation causes loss of bone mass and density whereas provision of moderate movement increases certain bone quality parameters during adulthood in laying hens.

Formation and characterisation of neuromuscular junctions between hiPSC derived motoneurons and myotubes.

Striated skeletal muscle cells from humans represent a valuable source for in vitro studies of the motoric system as well as for pathophysiological investigations in the clinical settings. Myoblasts can readily be grown from human muscle tissue. However, if muscle tissue is unavailable, myogenic cells can be generated from human induced pluripotent stem cells (hiPSCs) preferably without genetic engineering. Our study aimed to optimize the generation of hiPSCs derived myogenic cells by employing selection of CD34 positive cells and followed by distinct, stepwise culture conditions. Following the expansion of CD34 positive single cells under myogenic cell culture conditions, serum deprived myoblast-like cells finally fused and formed multinucleated striated myotubes that expressed a set of key markers for muscle differentiation. In addition, these myotubes contracted upon electrical stimulation, responded to acetylcholine (Ach) and were able to generate action potentials. Finally, we co-cultured motoneurons and myotubes generated from identical hiPSCs cell lines. We could observe the early aggregation of acetylcholine receptors in muscle cells of immature co-cultures. At later stages, we identified and characterised mature neuromuscular junctions (NMJs). In summary, we describe here the successful generation of an iPS cell derived functional cellular system consisting of two distinct communicating cells types. This in vitro co-culture system could therefore contribute to research on diseases in which the motoneurons and the NMJ are predominantly affected, such as in amyotrophic lateral sclerosis or spinal muscular atrophy.