Elevated adipogenesis of marrow mesenchymal stem cells during early steroid-associated osteonecrosis development

<p>Abstract</p> <p>Background</p> <p>Increased bone marrow lipid deposition in steroid-associated osteonecrosis (ON) implies that abnormalities in fat metabolism play an important role in ON development. The increase in lipid deposition might be explained by elevated adipogenesis of marrow mesenchymal stem cells (MSCs). However, it remains unclear whether there is a close association between elevated adipogenesis and steroid-associated ON development.</p> <p>Objective</p> <p>The present study was designed to test the hypothesis that there might be a close association between elevated adipogenesis and steroid-associated ON development.</p> <p>Methods</p> <p>ON rabbit model was induced based on our established protocol. Dynamic-MRI was employed for local intra-osseous perfusion evaluation in bilateral femora. Two weeks after induction, bone marrow was harvested for evaluating the ability of adipogenic differentiation of marrow MSCs at both cellular and mRNA level involving adipogenesis-related gene peroxisome proliferator-activated receptor gamma2 (PPARγ2). The bilateral femora were dissected for examining marrow lipid deposition by quantifying fat cell number, fat cell size, lipid deposition area and ON lesions. For investigating association among adipogenesis, lipid deposition and perfusion function with regard to ON occurrence, the rabbits were divided into ON⁺(with at least one ON lesion) group and ON^-(without ON lesion) group. For investigating association among adipogenesis, lipid deposition and perfusion function with regard to ON extension, the ON⁺rabbits were further divided into sub-single-lesion group (SON group: with one ON lesion) and sub-multiple-lesion group (MON group: with more than one ON lesion).</p> <p>Results</p> <p>Local intra-osseous perfusion index was found lower in either ON⁺or MON group when compared to either ON^-or SON group, whereas the marrow fat cells number and area were much larger in either ON⁺or MON group as compared with ON^-and SON group. The adipogenic differentiation ability of MSCs and PPARγ2 expression in either ON⁺or MON group were elevated significantly as compared with either ON^-or SON group.</p> <p>Conclusion</p> <p>These findings support our hypothesis that there is a close association between elevated adipogenesis and steroid-associated osteonecrosis development.</p

Blood perfusion assessed by dynamic MRI for Maximum Enhancement and Time-Signal Intensity

<p><b>Copyright information:</b></p><p>Taken from "Elevated adipogenesis of marrow mesenchymal stem cells during early steroid-associated osteonecrosis development"</p><p>http://www.josr-online.com/content/2/1/15</p><p>Journal of Orthopaedic Surgery and Research 2007;2():15-15.</p><p>Published online 15 Oct 2007</p><p>PMCID:PMC2146995.</p><p></p> (A) Maximum Enhancement at the examined sites (both proximal femora and distal femora, the similar pattern was found, data not shown here for distal femora) showed a significant decrease from baseline in ONrabbits at week 2 after steroid induction. There were significant decrease in Maximum Enhancement between ONand ONgroup, MON and SON group at week 2 (p < 0.05). (B) Representative Time-Signal Intensity curves from contrast-enhanced dynamic MRI on proximal femur. The Time-Signal Intensity curve showed a significant decrease in enhancement slope in ONgroup as compared with ONgroup at week 2

VisDrone-MOT2021: The Vision Meets Drone Multiple Object Tracking Challenge Results

Vision Meets Drone: Multiple Object Tracking (VisDrone-MOT2021) challenge - the forth annual activity organized by the VisDrone team - focuses on benchmarking UAV MOT algorithms in realistic challenging environments. It is held in conjunction with ICCV 2021. VisDrone-MOT2021 contains 96 video sequences in total, including 56 sequences (~24K frames) for training, 7 sequences (~3K frames) for validation and 33 sequences (~13K frames) for testing. Bounding-box annotations for novel object categories are provided every frame and temporally consistent instance IDs are also given. Additionally, occlusion ratio and truncation ratio are provided as extra useful annotations. The results of eight state-of-the-art MOT algorithms are reported and discussed. We hope that our VisDrone-MOT2021 challenge will facilitate future research and applications in the field of UAV vision. The website of our challenge can be found at http://www.aiskyeye.com/