50 research outputs found
Analytische Sterbealtersbestimmung von Skelettfunden: Möglichkeiten und Grenzen bei der Bearbeitung von historischem und rezentem Skelettmaterial
No full textThe aim of the present work is the research in age specific changes at human skeletal remains. Thereby references for the application of the methods for age estimation should be developed. With the optimized method the remains from the medieval graveyard Dresden-Briesnitz should be estimated. Based on the single age estimations the age structure of this population should be reconstructed. For the research skeletal remains with known age and sex from the 20th century were available. The recent series consists of Crania (n=300), Clavicles (n=41), Ossa coxae (n=50) and the Femora (n=83). From the medieval graveyard Dresden-Briesnitz up to 827 individuals were used. From this 411 adult individuals became part of the present work. For the methodological approach the age specific changes at the sutures of the skull, at the medial end of the Clavicle, at the Os coxae the Facies symphysialis, Facies auricularis and the Acetabulum, at the Os sacrum the Facies auricularis were compared with the chronological age at the recent material. Furthermore at the Femur and Humerus the changes in the proximal part and the microstructure in Femur, Tibia, Fibula and Humerus were observed. At the historical material the comparison was done with the changes at the Facies symphysialis and the histo-morphological changes in the Femur. The research in the age-specific changes showed, that the application of the morphological methods implied an extensive practice at remains with known age. The best results were achieved by the changes at the Facies symphysialis and the developed histo-morphologic method at the femur with the highest correspondence between the chronological and the estimated biological age. The histo-morphologic approach allows close estimates over the whole adolescent period. The methodological part of this approach, developed at the femur, is transferable to the tibia and the humerus. The Transition analysis, with the combination of the closure of the skull-sutures, the changes at the Facies symphysialis as well as auricularis at the hipbone is one of the most preferable methods in age estimation. The suture closure at the Tabula interna of the skull and the age specific changes at the Facies auricularis of the ilia can provide good information about age. But it is indispensible to consider the variability of the morphological characteristics and the wide age-ranges. Even the changes at the Acetabulum can give useful information to age at death. In the opposite, the changes at the obliteration at the Tabula externa of the skull especially the application of the lower sutures of the Neurocranium and the Viscerocranium shouldn’t be used for age estimation as single traits. After the orientation at the methods for age estimation with the recent material and the research in the age specific changes at the medieval material, age at death of the skeletons of Dresden-Briesnitz was estimated. The age structure of this graveyard was reconstructed with the single data of the skeletal individuals. A very low life expectancy of 26 years for the population of Dresden-Briesnitz was estimated. This low life span is correlated with the high rates of infant mortality. 50% of the individuals haven’t reached the adulthood. After overcoming the infant period the life span was growing. So many people reached the senile age cohort. Nearly the same number of men (n=115) and women (n=104) were buried at this graveyard. With the examination of Dresden-Briesnitz it was possible to close a gap in the anthropological reconstruction of the 10th – 13th century, which was an important period at the transition of the late Slavic to the early German settlement. A higher life span in the younger archaeological horizon (11th – 13th century) could be indicated for an optimization of the living conditions
Modulation of fixation stiffness from flexible to stiff in a rat model of bone healing
No full textConstant fixator stiffness for the duration of healing may not provide suitable mechanical conditions for all stages of bone repair. Therefore, we investigated the influence of stiffening fixation on callus stiffness and morphology in a rat diaphyseal osteotomy model to see if healing time was shortened and callus stiffness increased through modulation of fixation from flexible to stiff. \ud
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An external unilateral fixator was applied to the osteotimised femur and stiffened by decreasing the offset of the inner fixator bar at 3, 7, 14, and 21 days post-operation. After 5 weeks the rats were killed and healing was evaluated with mechanical, histological and micro-computed tomography methods. Constant fixation stiffness control groups with either stiff or flexible fixation were included for comparison.\ud
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The callus stiffness of the stiff group and all 4 experimental groups was greater than in the flexible group. The callus of the flexible group was larger but contained a higher proportion of unmineralized tissue and cartilage. The stiff and modulated groups (3, 7, 14, and 21 days) all showed bony bridging at 5 weeks, as well as signs of callus remodeling. Stiffening fixation at 7 and 14 days post-osteotomy produced the highest degree of callus bridging. Bone mineral density in the fracture gap was highest in animals where the fixation was stiffened after 14 days. \ud
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The predicted benefit of a large robust callus formed through early flexible fixation could not be shown, however the benefits of stabilizing a flexible construct to achieve timely healing was demonstrated at all time points
Description of skeletal phenotype of mouse strains
No full textThe study of fracture healing and the effects that can stimulate or delay this process are of common clinical interest. Many animal models were established to study fracture healing under defined conditions aiming to draw conclusion about the healing in humans. Due to the possibilities of genetic modifications, mouse strains became the optimal model in research of specific regulation levels in the complex field of regenerative medicine and research. Many groups clarified that genetic modification can significantly influence bone morphology and thus changes of bone growth, remodelling and fracture healing are presumed. Hence it is necessary to describe the skeletal phenotype of mouse strains by precisely analysing the bone morphology before starting further studies.There are single studies that gave an appropriate concept in description of the phenotype of mouse-strains. We developed an optimized protocol for the description of bone properties in different mice by use of micro-Ct, biomechanical and histo-morphometric parameters.<br/
Injured—but special? On associations between skull defects and burial treatment in the Corded Ware Culture of central Germany
No full textWhat It Takes to Get Proactive: An Integrative Multilevel Model of the Antecedents of Personal Initiative
No full textBuilding upon and extending Parker, Bindl, and Strauss's (2010) theory of proactive motivation, we develop an integrated, multilevel model to examine how contextual factors shape employees' proactive motivational states and, through these proactive motivational states, influence their personal initiative behavior. Using data from a sample of hotels collected from 3 sources and over 2 time periods, we show that establishment-level initiative-enhancing human resource management (HRM) systems were positively related to departmental initiative climate, which was positively related to employee personal initiative through employee role-breadth self-efficacy. Further, department-level empowering leadership was positively related to initiative climate only when initiative-enhancing HRM systems were low. These findings offer interesting implications for research on personal initiative and for the management of employee proactivity in [email protected]
Distinct frequency dependent effects of whole‐body vibration on non‐fractured bone and fracture healing in mice
No full textAutologous Mesenchymal Stroma Cells Are Superior to Allogeneic Ones in Bone Defect Regeneration
No full textThe application of autologous mesenchymal stem cells (MSC) for the treatment of bone defects requires two invasive procedures and several weeks of ex vivo cell expansion. To overcome these limitations, the administration of allogeneic MSC may be attractive, because they are anticipated to be immunoprivileged. Because preclinical studies using various animal models are conflicting with respect to the efficacy of allogeneic MSC, we investigated whether autologous and allogeneic human MSC (hMSC) are equally effective in regenerating bone in a humanized mouse model resembling the human immune system. Applying autologous and allogeneic hMSC in critically sized femoral defects, we found that allogeneic hMSC elicited a mild immune response early after implantation, whereas early angiogenic processes were similar in both treatments. At later healing time points, the transplantation of allogeneic hMSC resulted in less bone formation than autologous hMSC, associated with a reduced expression of the osteogenic factor Runx2 and impaired angiogenesis. We found by species-specific staining for collagen-type-1α2 that MSCs of either source did not synthesize new bone matrix, indicating an indirect contribution of transplanted hMSC to bone regeneration. In conclusion, our data suggest that the application of autologous hMSC is superior to that of allogeneic cells for bone defect treatment
Systemic inflammation induced by a thoracic trauma alters the cellular composition of the early fracture callus
No full textFracture Healing Is Delayed in Immunodeficient NOD/scid‑IL2Rγcnull Mice.
No full textFollowing bone fracture, the repair process starts with an inflammatory reaction at the fracture site. Fracture healing is disturbed when the initial inflammation is increased or prolonged, whereby, a balanced inflammatory response is anticipated to be crucial for fracture healing, because it may induce down-stream responses leading to tissue repair. However, the impact of the immune response on fracture healing remains poorly understood. Here, we investigated bone healing in NOD/scid-IL2Rγcnull mice, which exhibit severe defects in innate and adaptive immunity, by biomechanical testing, histomorphometry and micro-computed tomography. We demonstrated that NOD/scid-IL2Rγcnull mice exhibited normal skeletal anatomy and a mild bone phenotype with a slightly reduced bone mass in the trabecular compartment in comparison to immunocompetent Balb/c mice. Fracture healing was impaired in immunodeficient NOD/scid-IL2Rγcnull mice. Callus bone content was unaffected during the early healing stage, whereas it was significantly reduced during the later healing period. Concomitantly, the amount of cartilage was significantly increased, indicating delayed endochondral ossification, most likely due to the decreased osteoclast activity observed in cells isolated from NOD/scid-IL2Rγcnull mice. Our results suggest that--under aseptic, uncomplicated conditions--the immediate immune response after fracture is non-essential for the initiation of bone formation. However, an intact immune system in general is important for successful bone healing, because endochondral ossification is delayed in immunodeficient NOD/scid-IL2Rγcnull mice
Systemic treatment with the sphingosine‐1‐phosphate analog FTY720 does not improve fracture healing in mice
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