Résumé :
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One of the most important and time-consuming challenge in vivo studies of neuro-muscular diseases is to precisely monitor subtle and significant modifications of thecharacteristics within the myofiber population. To date, counting and shape description are performed manually. Here we describe a program for the ImageJ platformthat allows automated multiparametric description of mouse muscle fibers in tissue cross sections. Using reconstructed labeled (DAPI, Lectin, GFP labeling) denervated(acute muscle atrophy model) or normal mouse muscle slices as input, our program generates as ouput, a result table describing individual muscle fibers with thefollowing parameters:Position, Size, GFP content (quantitation), Number of central nuclei.Currently our program is able to find more than 90% of all fibers with anexcellent (size vs number) correlation with 3 independent human analyses. The single fiber cross-sectional surface correlation between CPU and 3 humans is 0,9589+/- 0,0008, whereas between humans this value is 0,9863 +/- 0,0006 (Fig. 1). Moreover, our program is able to find 93% of the central nuclei, whereas the differenthumans identify a maximum of 85%. The automated process, from drawing the perimeter of individual fibers, to calculations of surface area, for all of the fibers in a crosssection, requires less time (about 7h), than it takes for a human to only trace the perimeter of the fibers (10h +/- 2h). We have developed the interface so as to permit fastquality control by eye. Moreover, analysis tools have been developed to perform easy cell gating and subpopulation identification and labeling, including multiparametricgraphic representation.This program has already been successfully implemented on cross sections of OF-1 mice tibialis anterior (denervated or not), and on mTor KOmice soleus, plataris and gastrocnemius.This program is a powerful tool allowing rapid characterization of muscle fibers from classic cross sections, accelerating andenhancing the precision of the experimental data recovery and processing at the individual fiber level.
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