30 research outputs found

    Low-Level Vibrations Retain Bone Marrow's Osteogenic Potential and Augment Recovery of Trabecular Bone during Reambulation

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    Mechanical disuse will bias bone marrow stromal cells towards adipogenesis, ultimately compromising the regenerative capacity of the stem cell pool and impeding the rapid and full recovery of bone morphology. Here, it was tested whether brief daily exposure to high-frequency, low-magnitude vibrations can preserve the marrow environment during disuse and enhance the initiation of tissue recovery upon reambulation. Male C57BL/6J mice were subjected to hindlimb unloading (HU, n = 24), HU interrupted by weight-bearing for 15 min/d (HU+SHAM, n = 24), HU interrupted by low-level whole body vibrations (0.2 g, 90 Hz) for 15 min/d (HU+VIB, n = 24), or served as age-matched controls (AC, n = 24). Following 3 w of disuse, half of the mice in each group were released for 3 w of reambulation (RA), while the others were sacrificed. RA+VIB mice continued to receive vibrations for 15 min/d while RA+SHAM continued to receive sham loading. After disuse, HU+VIB mice had a 30% greater osteogenic marrow stromal cell population, 30% smaller osteoclast surface, 76% greater osteoblast surface but similar trabecular bone volume fraction compared to HU. After 3 w of reambulation, trabecular bone of RA+VIB mice had a 30% greater bone volume fraction, 51% greater marrow osteoprogenitor population, 83% greater osteoblast surfaces, 59% greater bone formation rates, and a 235% greater ratio of bone lining osteoblasts to marrow adipocytes than RA mice. A subsequent experiment indicated that receiving the mechanical intervention only during disuse, rather than only during reambulation, was more effective in altering trabecular morphology. These data indicate that the osteogenic potential of bone marrow cells is retained by low-magnitude vibrations during disuse, an attribute which may have contributed to an enhanced recovery of bone morphology during reambulation

    Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)

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    Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1.

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    In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field

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    Flow cytometry of bone marrow cells.

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    <p>(<b>A</b>) Size and granularity distribution of total bone marrow cells. Region of interest was selected to include single and viable cell populations. (<b>B</b>) Fluorescence of cells that were positive for SCA-1 and CD90.2 surface antigens according to fluorescence intensity. Ratio of SCA-1 and CD90.2 positive cells to total gated cells (<b>C</b>) after 3 w and (<b>D</b>) after 6 w of the experiment. Data are mean ± SD. Groups were compared by ANOVA followed by SNK. Letters denominate significant (p<0.05) differences between groups: <b>+</b> any group different from AC; § HU+SHAM (RA+SHAM) or HU+VIB (RA+VIB) different from HU (RA); # HU+VIB (RA+VIB) different from HU+SHAM (RA+SHAM).</p

    Bone formation in the metaphysis of the proximal tibia.

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    <p>Static and dynamic indices of bone formation at trabecular bone surfaces of (<b>A-C</b>) age-matched controls (AC), hindlimb unloaded (HU), sham loaded (HU+SHAM), and vibrated mice (HU+VIB) after the initial 3 w phase and of (<b>D-F</b>) age-matched controls (AC), reambulation (RA), sham loaded (RA+SHAM), and vibrated mice (RA+VIB) at the end of the 6 w experimental phase. Data are mean ± SD. Groups were compared by ANOVA followed by SNK. Letters denominate significant (p<0.05) differences between groups: <b>+</b> any group different from AC; § HU+SHAM (RA+SHAM) or HU+VIB (RA+VIB) different from HU (RA); # HU+VIB (RA+VIB) different from HU+SHAM (RA+SHAM).</p

    Comparison between vibrations applied during unloading vs reambulation.

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    <p>Longitudinal changes in (<b>A</b>) bone marrow area (Ma.Ar), (<b>B</b>) trabecular bone volume (BV), and (<b>c</b>) trabecular bone volume fraction (BV/TV) of the tibial metaphysis in mice that either received vibrations <i>only</i> during the unloading period (VIB-HU, n = 6) or <i>only</i> during reambulation (VIB-RA, n = 6). Open triangles correspond to-cross-sectional data of age-matched control mice (n = 12). Relative differences and p-values are given for the comparison between VIB-HU and VIB-RA mice.</p

    Bone morphology in the metaphysis of the proximal tibia.

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    <p>Trabecular bone volume fraction (BV/TV) of the proximal tibia in (<b>A</b>) age-matched controls (AC), hindlimb unloaded (HU), sham loaded (HU+SHAM), and vibrated (HU+VIB) mice after 3 w of disuse and (<b>B</b>) age-matched controls (AC), reambulation (RA), sham loaded (RA+SHAM), and vibrated (RA+VIB) mice after 3 w of disuse followed by 3 w of reambulation. Data are mean ± SD. Groups were compared by ANOVA followed by SNK. Letters denominate significant (p<0.05) differences between groups: <b>+</b> any group different from AC; § HU+SHAM (RA+SHAM) or HU+VIB (RA+VIB) different from HU (RA); # HU+VIB (RA+VIB) different from HU+SHAM (RA+SHAM).</p
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