Browsing by Author "Sibole, Scott C."

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    High-Fat High-Sucrose Diet Leads to Dynamic Structural and Inflammatory Alterations in the Rat Vastus Lateralis Muscle
    (Journal of Orthopaedic Research, 2016) Herzog, Walter; Collins, Kelsey; Hart, David A.; Reimer, Raylene A.; Seerattan, Ruth A.; Banker, Christine W.; Sibole, Scott C.
    The influence of obesity on muscle integrity is not well understood. The purpose of this study 37 was to quantify structural and molecular changes in the rat vastus lateralis (VL) muscle as a 38 function of a 12-week obesity induction period and a subsequent adaptation period (additional 39 16-weeks). Male Sprague-Dawley rats consumed a high-fat, high-sucrose (DIO, n=40) diet or a 40 chow control-diet (n=14). At 12-weeks, DIO rats were grouped as prone (DIO-P, top 33% of 41 weight change) or resistant (DIO-R, bottom 33%). Animals were euthanized at 12-weeks or 28-42 weeks on the diet. At sacrifice, body composition was determined and VL muscles were 43 collected. Intramuscular fat, fibrosis, and CD68+ cells were quantified histologically and 44 relevant molecular markers were evaluated using RT-qPCR. At 12- and 28-weeks post obesity 45 induction, DIO-P rats had more mass and body fat than DIO-R and chow rats (p<0.05). DIO-P 46 and DIO-R rats had similar losses in muscle mass, which were greater than those in chow rats 47 (p<0.05). mRNA levels for MAFbx/atrogin1 were reduced in DIO-P and DIO-R rats at 12- and 48 28-weeks compared to chow rats (p<0.05), while expression of MURF was similar to chow 49 values. DIO-P rats demonstrated increased mRNA levels for pro-inflammatory mediators, 50 inflammatory cells, and fibrosis compared to DIO-R and chow animals, despite having similar 51 levels of intramuscular fat. The down-regulation of MAFbx/atrogin1 may suggest onset of 52 degenerative changes in VL muscle integrity of obese rats. DIO-R animals exhibited fewer 53 inflammatory changes compared to DIO-P animals, suggesting a protective effect of obesity 54 resistance on local inflammation.
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    In vivo Sarcomere Lengths and Sarcomere Elongations Are Not Uniform across an Intact Muscle
    (Frontiers in Physiology, 2016-05) Herzog, Walter; Moo, Eng Kuan; Fortuna, Rafael; Sibole, Scott C.; Abusara, Ziad
    Sarcomere lengths have been a crucial outcome measure for understanding and explaining basic muscle properties and muscle function. Sarcomere lengths for a given muscle are typically measured at a single spot, often in the mid-belly of the muscle, and at a given muscle length. It is then assumed implicitly that the sarcomere length measured at this single spot represents the sarcomere lengths at other locations within the muscle, and force-length, force-velocity, and power-velocity properties of muscles are often implied based on these single sarcomere length measurements. Although, intuitively appealing, this assumption is yet to be supported by systematic evidence. The objective of this study was to measure sarcomere lengths at defined locations along and across an intact muscle, at different muscle lengths. Using second harmonic generation (SHG) imaging technique, sarcomere patterns in passive mouse tibialis anterior (TA) were imaged in a non-contact manner at five selected locations (“proximal,” “distal,” “middle,” “medial,” and “lateral” TA sites) and at three different lengths encompassing the anatomical range of motion of the TA. We showed that sarcomere lengths varied substantially within small regions of the muscle and also for different sites across the entire TA. Also, sarcomere elongations with muscle lengthening were non-uniform across the muscle, with the highest sarcomere stretches occurring near the myotendinous junction. We conclude that muscle mechanics derived from sarcomere length measured from a small region of a muscle may not well-represent the sarcomere length and associated functional properties of the entire muscle.
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    pyCellAnalyst: Extensive Software for Three-dimensional Analysis of Deforming Cells
    (2016) Sibole, Scott C.; Herzog, Walter; Federico, Salvatore; Epstein, Marcelo; Edwards, Brent; Boyd, Steven; Alim, Usman
    Laser scanning microscopy has proven to be a transformative tool in the biomedical sciences. The technology provides a means to image three-dimensional, time-varying, micro-scale features within living tissue, which in turn has borne exciting avenues for the experimental investigation of the relationship between the hierarchical spatial scales within organisms. By coupling laser scanning microscopes to mechanical testing systems, one can study the relationships between mechanics at the organ, tissue, and cellular scales. In practice, while a controlled mechanical state is applied to intact tissue, images of the cells within can be obtained via microscopy; however, extracting the geometric information from these images and characterizing deformation has been a challenge to the field. pyCellAnalyst is an extensive software framework for such analysis of these image data. It provides an accessible interface to reconstruct cellular geometries from images, characterize deformation, and perform finite element analyses informed by the experimental observations.