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Increased expression of TGF-β in the cochlear fibroblast of diabetic model rats
Published in Cut Adeya Adella, Stem Cell Oncology, 2018
Haemodynamic changes and microcirculation disorders that are often found in diabetic conditions also happened in the cochlea. The studies showed that, especially in stria vascularis, vascular changes in the cochlea including thickening of the capillary walls (Xipeng et al., 2013). The increase in extracellular matrix accumulation through the stimulation of type IV collagen and the production of fibronectin (Russo et al., 2007), and the increase in Connective Tissue Growth Factor (CTGF), as well as Vascular Endothelial Growth Factor (VEGF) (Lee, 2013), all known to be induced by TGF-β. In 2013, a study showed that the TGF-β serum level in patients suffering from diabetes with diabetic retinopathy was significantly higher compared to diabetic patients without diabetic retinopathy (Zorena et al., 2013).
Disorders of Hearing
Published in Anthony N. Nicholson, The Neurosciences and the Practice of Aviation Medicine, 2017
Linda M. Luxon, Ronald Hinchcliffe
The internal ear is embedded in the bony labyrinth filled with perilymph, and can be divided into three anatomical and functional regions: the semicircular canals, the vestibule and the cochlea. Within the bony labyrinth lies the membranous labyrinth which is filled with endolymph and contains the sensory cells of both hearing and balance. The bony cochlea resembles the shell of a snail, within which lies the cochlear duct with a flat floor known as the spiral lamina, a side wall which is comprised mainly of the stria vascularis and a sloping diagonal ‘roof’ known as the vestibular membrane of Reissner (1824–1878) (Figure 19.2). The spiral organ of Corti (1822–1876) is situated on the basilar membrane and contains the auditory sensory receptor cells known as hair cells. There are two types of cells, the inner and the outer hair cells, both of which have stereocilia projecting from their upper endolymphatic surface. The stereocilia are embedded in the gelatinous tectorial membrane.
Basic principles
Published in Michael Talbot-Smith, Audio Engineer's Reference Book, 2013
John Ratcliff, Talbot-Smith Michael, J. Patrick Wilson, Louis D. Fielder, Glynne Parry, Richard Tyler, Michael Gayford, Roger Derry
The central channel (scala media) is separated from the scala vestibuli by a thin membrane of negligible stiffness, Reissner�s membrane, and from the scala tympani by a membrane of graded stiffness (the basilar membrane) which also supports the organ of Corti. Scala media is filled with endolymph which is low in potassium ions and is maintained at a positive potential of +80 mV by the stria vascularis attached to the bony wall of the cochlea and acting as an electrical battery. The organ of Corti contains one row of inner hair cells at its inner edge and, separated by the rods of Corti, three to five rows of outer hair cells situated over the middle of the basilar membrane. The upper ends of all the hair cells are integral with a plate-like structure (the reticular lamina) through which the hairs or stereocilia protrude and make contact or near contact with the tectorial membrane. The latter is a gelatinous substance, attached to the limbus on the inner side of the cochlea, against which the stereocilia are bent when the basilar membrane is displaced by sound.
Evaluation of potential health effects associated with occupational and environmental exposure to styrene – an update
Published in Journal of Toxicology and Environmental Health, Part B, 2019
M.I. Banton, J.S. Bus, J.J. Collins, E. Delzell, H.-P. Gelbke, J.E. Kester, M.M. Moore, R. Waites, S.S. Sarang
A recent mechanistic study supports the importance of oxidative stress in ototoxicity and provides further definition of cochlear responses to styrene treatment. Fetoni et al. (2016) evaluated the efficacy of the water-soluble coenzyme Q10 analog Qter® in protecting against ototoxicity (evaluated by ABR threshold and amplitude of DPOAEs) and combating oxidative stress (as evidenced by production of superoxide anion and lipid peroxidation) in both OHCs and Deiters’ cells from rats administered 400 mg styrene/kg bw via gavage in olive oil for 1, 2, or 3 weeks. Coenzyme Q10 is a component of the electron transport chain and participates in aerobic cellular respiration. This substance performs as an electron carrier and hence can act as a free-radical scavenging antioxidant. As reported by others, styrene at this dose impacted hearing most strongly at mid-frequencies and caused preferential damage to Deiters’ cells and OHCs in the cochlear middle turn, with a gradient of increasingly severe injury from the third to first OHC rows. There was a much smaller impact on SGNs in the middle turn. Styrene increased superoxide levels in the organ of Corti, SGNs, and the stria vascularis, and increased 8-isoprostane expression (a biomarker of lipid peroxidation) primarily in the stria vascularis and SGNs, with greater involvement of Deiters’ cells than OHCs.