Tympanic membrane retraction used to manage tympanic membrane retraction, with the aims of preventing or relieving hearing loss and cholesteatoma formation. As retraction pockets may remain stable or resolve spontaneously, it may be appropriate to observe them for a period of time before considering any active treatment. The Valsalva maneuver increases middle ear pressure and can push a retracted eardrum out of the middle ear if is not adherent to middle ear structures. Hearing may improve as a result, however it can be a painful maneuver. The benefits are typically only temporary. Middle ear pressure can also be increased by Politzerization and with
Integral membrane protein at atomic resolution by X-ray crystallography or nuclear magnetic resonance spectroscopy. They are challenging subjects for study owing to the difficulties associated with extraction and crystallization. In addition, structures of many water-soluble protein domains of IMPs are available in the Protein Data Bank. Their membrane-anchoring α-helices have been removed to facilitate the extraction and crystallization. Search integral membrane proteins in the PDB (based on gene ontology classification) IMPs can be divided into two groups: The most common type of IMP is the transmembrane protein (TM), which spans the entire biological membrane. Single-pass membrane proteins cross the membrane only once, while