title: Analysis of muscle fiber clustering in the diaphragm muscle of sarcopenic mice.
abstract: BACKGROUND
  Sarcopenia likely comprises muscle fiber denervation and re-innervation, resulting in clustering of muscle fibers of the same type (classified by myosin heavy chain isoform composition). Development of methodology to quantitatively evaluate clustering of muscle fibers according to fiber type is necessary.
  
  
  METHODS
  Fiber type specific immunofluorescence histology was used to quantify fiber clustering in murine diaphragm muscle (n = 15) at ages 6 and 24 months.
  
  
  RESULTS
  With age, fiber type clustering is evidenced by fiber type specific changes in distances between fibers, specifically a 14% decrease to the closest fiber for type I and 24% increase for type IIx and/or IIb fibers (P < 0.001). Additionally, a 34% increase to the 3 closest type IIx and/or IIb fibers was found (P < 0.001).
  
  
  CONCLUSIONS
  This novel method of analyzing fiber type clustering may be useful in examining pathophysiological conditions of motor unit loss in neuromuscular disorders, myopathies, dystrophies, injuries, or amyotrophic lateral sclerosis.
authors: Department of Physiology and Biomedical Engineering, Mayo Clinic, 200 First Street SW, SMH Jo 4-184, Rochester, Minnesota, 55905, USA.
authors: Sarah M
authors: SM
authors: Greising
authors: Department of Physiology and Biomedical Engineering, Mayo Clinic, 200 First Street SW, SMH Jo 4-184, Rochester, Minnesota, 55905, USA.
authors: Juan S
authors: JS
authors: Medina-Martínez
authors: Department of Physiology and Biomedical Engineering, Mayo Clinic, 200 First Street SW, SMH Jo 4-184, Rochester, Minnesota, 55905, USA.
authors: Amrit K
authors: AK
authors: Vasdev
authors: Department of Physiology and Biomedical Engineering, Mayo Clinic, 200 First Street SW, SMH Jo 4-184, Rochester, Minnesota, 55905, USA.|Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota, USA.
authors: Gary C
authors: GC
authors: Sieck
authors: Department of Physiology and Biomedical Engineering, Mayo Clinic, 200 First Street SW, SMH Jo 4-184, Rochester, Minnesota, 55905, USA.|Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota, USA.
authors: Carlos B
authors: CB
authors: Mantilla
mesh_terms: D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D003964:Diaphragm / Q000473:pathology*; D004195:Disease Models, Animal; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018485:Muscle Fibers, Skeletal / Q000145:classification / Q000473:pathology*; D018995:Myosin Heavy Chains / Q000378:metabolism; D020033:Protein Isoforms; D012508:Sarcolemma / Q000473:pathology; D055948:Sarcopenia / Q000473:pathology*
chemical_list: D020033:Protein Isoforms; D018995:Myosin Heavy Chains
keywords: aging; cross-sectional area; fiber type; motor unit; myosin heavy chain; sarcopenia