Tympanometry versus direct middle ear pressure measurement in an artificial model: is tympanometry an accurate method to measure middle ear pressure?
Tympanometry does not yield precise ME pressure values. In a model with a larger "mastoid" and an actual pressure range of -46.8 to -93.6 mmH2O tympanometric readings are somewhat less unreliable (error of 40%-20%). However, tympanometry is in error of more than 400% in a model with a small mastoid in which the actual ME pressure is only slightly negative (i.e., range between -3.9 and -46.8 mmH2O). Therefore, this study implies that tympanometry has little use for measuring ME pressure especially in chronic ears or their sequelae that are usually characterized by having small negative pressures and small mastoids.
Results provide direct evidence supporting the presence of VSELs in adult mouse pancreas and their role during regeneration. VSELs are an interesting alternative to ES/iPS cells to regenerate a diabetic pancreas in future.