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排序方式: 共有2710条查询结果,搜索用时 15 毫秒
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A. Karunaratne A. Boyde C.T. Esapa J. Hiller N.J. Terrill S.D.M. Brown R.D. Cox R.V. Thakker H.S. Gupta 《BONE》2013,52(2):689-698
In metabolic bone diseases, the alterations in fibrillar level bone-material quality affecting macroscopic mechanical competence are not well-understood quantitatively. Here, we quantify the fibrillar level deformation in cantilever bending in a mouse model for hereditary rickets (Hpr). Microfocus in-situ synchrotron small-angle X-ray scattering (SAXS) combined with cantilever bending was used to resolve nanoscale fibril strain in tensile- and compressive tissue regions separately, with quantitative backscattered scanning electron microscopy used to measure microscale mineralization. Tissue-level flexural moduli for Hpr mice were significantly (p < 0.01) smaller compared to wild-type (~ 5 to 10-fold reduction). At the fibrillar level, the fibril moduli within the tensile and compressive zones were significantly (p < 0.05) lower by ~ 3- to 5-fold in Hpr mice compared to wild-type mice. Hpr mice have a lower mineral content (24.2 ± 2.1 Ca wt.% versus 27.4 ± 3.3 Ca wt.%) and its distribution was more heterogeneous compared to wild-type animals. However, the average effective fibril modulus did not differ significantly (p > 0.05) over ages (4, 7 and 10 weeks) between tensile and compressive zones. Our results indicate that incompletely mineralized fibrils in Hpr mice have greater deformability and lower moduli in both compression and tension, and those compressive and tensile zones have similar moduli at the fibrillar level. 相似文献
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Lin Li Ajinkya Sase Sudarshan Patil Berta Sunyer Harald Höger Karl-Heinz Smalla Oliver Stork Gert Lubec 《Hippocampus》2013,23(8):672-683
Protein phosphorylation and dephosphorylation events play a key role in memory formation and various protein kinases and phosphatases have been firmly associated with memory performance. Here, we determined expression changes of protein kinases and phosphatases following retrieval of spatial memory in CD1 mice in a Morris Water Maze task, using antibody microarrays and confirmatory Western blot. Comparing changes following single and consecutive retrieval, we identified stably and differentially expressed kinases, some of which have never been implicated before in memory functions. On the basis of these findings we define a small signaling network associated with spatial memory retrieval. Moreover, we describe differential regulation and correlation of expression levels with behavioral performance of polo‐like kinase 1. Together with its recently observed genetic association to autism‐spectrum disorders our data suggest a role of this kinase in balancing preservation and flexibility of learned behavior. © 2013 Wiley Periodicals, Inc. 相似文献
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Rachel E. Ward Alycia Fong Yan Karl F. Orishimo Ian J. Kremenic Marshall Hagins Marijeanne Liederbach Claire E. Hiller Evangelos Pappas 《Scandinavian journal of medicine & science in sports》2019,29(1):71-81
Repetition of jumps in dance and sport training poses a potential injury risk; however, non‐contact landing injuries are more common in athletes than dancers. This study aimed to compare the lower limb stiffness characteristics of dancers and athletes during drop landings to investigate possible mechanisms of impact‐related injuries. Kinematics and kinetics were recorded as 39 elite modern and ballet dancers (19 men and 20 women) and 40 college‐level team sport athletes (20 men and 20 women) performed single‐legged drop landings from a 30‐cm platform. Vertical leg stiffness and joint stiffness of the hip, knee, and ankle were calculated using a spring‐mass model. Stiffness data, joint kinematics, and moments were compared with a group‐by‐sex 2‐way analysis of variance. Multiple linear regression was used to assess the relative contribution of hip and knee and ankle joint stiffness to variance in overall vertical leg stiffness for dancers and athletes. Dancers had lower leg (P < 0.001), knee joint (P = 0.034), and ankle joint stiffness (P = 0.043) than athletes. This was facilitated by lower knee joint moments (P = 0.012) and greater knee (P = 0.029) and ankle joint (P = 0.048) range of motion in dancers. Males had higher leg (P < 0.001) and ankle joint stiffness (P < 0.001) than females. This occurred through lower ankle range of motion (P < 0.001) and greater ankle moment (P = 0.022) compared to females. Male and female dancers demonstrated reduced lower limb stiffness compared to athletes, indicating a more pliable landing technique. Dance training techniques could potentially inform approaches to injury prevention in athletes. 相似文献
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Thal DR Larionov S Abramowski D Wiederhold KH Van Dooren T Yamaguchi H Haass C Van Leuven F Staufenbiel M Capetillo-Zarate E 《Neurobiology of aging》2007,28(8):1221-1230
The deposition of the amyloid beta-protein (Abeta) is a hallmark of Alzheimer's disease (AD). One reason for Abeta-accumulation and deposition in the brain may be an altered drainage along perivascular channels. Extracellular fluid is drained from the brain towards the cervical lymph nodes via perivascular channels. The perivascular space around cerebral arteries is the morphological correlative of these drainage channels. Here, we show that Abeta is immunohistochemically detectable within the perivascular space of 25 months old wild-type and amyloid precursor protein (APP)-transgenic mice harboring the Swedish double mutation driven by a neuron specific promoter. Only small amounts of Abeta can be detected immunohistochemically in the perivascular space of wild-type mice. Cerebrovascular and parenchymal Abeta-deposits were absent. In APP-transgenic mice, large amounts of Abeta were found in the perivascular drainage channels accompanied with cerebrovascular and parenchymal Abeta-deposition. The apolipoprotein E (apoE) immunostaining within the perivascular channels did not vary between wild-type and APP-transgenic mice. Almost 100% of the area that represents the perivascular space was stained with an antibody directed against apoE. Here, Abeta co-localized with apoE indicating an involvement of apoE in the perivascular clearance of Abeta. Fibrillar congophilic amyloid was not seen in wild-type mice. In APP-transgenic animals, congophilic fibrillar amyloid material was seen in the wall of cerebral blood vessels but not in the perivascular space. In conclusion, our results suggest that non-fibrillar forms of Abeta are drained along perivascular channels and that apoE is presumably involved in this clearance mechanism. Overloading such a clearance mechanism in APP-transgenic mice appears to result in insufficient Abeta-clearance, increased Abeta-levels in the brain and the perivascular drainage channels, and finally in Abeta-deposition. In so doing, our results strengthen the hypothesis that an alteration of perivascular drainage supports Abeta-deposition and the development of AD. 相似文献
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Sawatzky B Denison I Langrish S Richardson S Hiller K Slobogean B 《Archives of physical medicine and rehabilitation》2007,88(11):1423-1428
Sawatzky B, Denison I, Langrish S, Richardson S, Hiller K, Slobogean B. The Segway Personal Transporter as an alternative mobility device for people with disabilities: a pilot study.