Analysis Tools
muscle
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• number of IgG positive fibers is increased in tibialis anterior muscles and in the diaphragm
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• extensor digitorum longus muscles are smaller at 3 months of age, not different at 6 months of age, and heavier at 12 months
• however, gastrocnemius muscle mass is not different at any age
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• tibialis anterior muscles show an increase in myofiber size at 6 and 12 months of age, with increased proportion of both smaller and larger muscle fibers
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• mice exhibit variable and increased muscle fiber size at 3, 5, and 12 months of age
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• tibialis anterior muscles show a 40%, 48%, and 59% increase in the proportion of fibers with centrally-located nuclei at 3, 6, and 12 months of age, respectively
• diaphragm shows an increase in centrally-located nuclei at all ages
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• normalized masses of tibialis anterior and soleus muscles are heavier at 3, 6, and 12 months of age
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• tibialis anterior muscles show a shift towards a faster phenotype with a reduction in the proportion of type IIa fibers at 6 and 12 months of age, and increased size of IIa and IIb fibers at 6 and 12 months of age, respectively, but no change in fiber oxidative capacity
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• limb muscle hypertrophy, with hypertrophy of the tibialis anterior and soleus muscles, variable changes in mass of the extensor digitorum longus, and no change in the gastrocnemius
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• tibialis anterior muscles show an increase in fibrosis at 3 months and 6 months, with a trend towards increase at 12 months
• diaphragm shows an increase in fibrosis at all ages
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• some areas of calcification are seen in tibialis anterior muscles at all ages
• ectopic myofiber calcification in diaphragm at 3, 6, and 12 months of age, which is reduced with increasing age
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• 3-month-old mice exhibit dystrophic pathology in tibialis anterior muscles and diaphragm, with the presence of inflammatory infiltrate, variable fiber size, and centrally nucleated fibers
• number of IgG positive fibers is increased in tibialis anterior muscles and in the diaphragm
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• muscles are more susceptible to contraction-induced injury and the force deficits are exacerbated with age
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• twitch and tetanic forces are higher at 6 months, but not at 3 or 12 months, of age
• when normalized for changes in muscle cross-sectional area, specific force is lower at 3 and 12 months of age, but not at 6 months
• time-to-peak tension is faster only at 6 months of age, and one-half relaxation time is faster at 3 and 6 months, but not 12 months of age
• the rate of twitch contraction (dP/dt) is increased only at 6 months of age
• muscles from 3- and 6-month-old mice produce less force at lower frequencies, but 6-month-old mice produce greater force at higher frequencies (above 100 Hz), however force production is normal at all stimulation frequencies at 12 months of age
• normalized force production is reduced in muscles at 3, 6, and 12 months of age; force production at lower frequencies is reduced at all ages, but at higher frequencies only at 12 months of age
• muscles exhibit higher susceptibility to contraction-induced injury as indicated by higher force deficits after repeated lengthening contractions; when tibialis anterior muscles are stretched by up to 30% fiber length, the force deficit for 3-, 6-, and 12-month-old mice averages 24%, 44%, and 61% from the initial (uninjured) force, respectively, compared to 4%, 3%, and 19%, respectively, for wild-type mice
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skeleton
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• lengthening of the tibial crest due to the larger, adjacent tibialis anterior muscle
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• tibial cortical bone has a larger diaphysis at 6 months of age and a greater normalized bone area, areal tissue mineral density, and cortical thickness at 12 months of age
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• cortical bone has greater cortical thickness at 12 months of age
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• mice exhibit defects in trabecular bone development, with a delay in trabecular bone mass accrual
• trabecular bone mass and number are unchanged between 3 and 6 months of age compared to continued trabecular bone development in wild-type mice
• the loss of trabecular bone that is seen in 12-month-old wild-type mice is attenuated and mice exhibit more trabecular bone mass at 12 months than wild-type mice
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adipose tissue
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• mice exhibit reduced epididymal fat mass at all ages
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• mice exhibit reduced epididymal fat mass at all ages
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cardiovascular system
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• normalized heart mass is not different at 3 months of age but is lower at 6 and 12 months of age
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• mice exhibit sarcoplasmic reticulum calcium ATPase (SERCA) pump dysfunction in the heart
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growth/size/body
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• mice exhibit reduced epididymal fat mass at all ages
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• mice tend to be heavier, with significant greater body mass at 3 and 6 months of age, but no change in body mass at 12 months of age
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• mice show enlarged liver at 3 months of age, but not at 6 or 12 months of age
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• mice show enlarged spleen at 3 months of age, but not at 6 or 12 months of age
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hematopoietic system
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• mice show enlarged spleen at 3 months of age, but not at 6 or 12 months of age
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homeostasis/metabolism
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• serum aspartate transaminase levels are increased at 3, 6, and 12 months of age, indicating muscle damage
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immune system
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• mice show enlarged spleen at 3 months of age, but not at 6 or 12 months of age
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limbs/digits/tail
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• extensor digitorum longus muscles are smaller at 3 months of age, not different at 6 months of age, and heavier at 12 months
• however, gastrocnemius muscle mass is not different at any age
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• lengthening of the tibial crest due to the larger, adjacent tibialis anterior muscle
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liver/biliary system
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• mice show enlarged liver at 3 months of age, but not at 6 or 12 months of age
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Mouse Models of Human Disease |
DO ID | OMIM ID(s) | Ref(s) | |
| Duchenne muscular dystrophy | DOID:11723 |
OMIM:310200 |
J:353371 | |
