Response of cochlear blood flow to prostaglandin E1 applied topically to the round window.

Conclusions: The increase in cochlear blood flow (CBF) after administration of prostaglandin E1 (PGE1) to the round window depends on increased blood flow through the anterior inferior cerebellar artery (AICA).

Objectives: To evaluate the response of CBF to PGE1 applied topically to the round window, and to investigate the origin of blood flow changes after this topical application.

Material And Methods: The response of CBF to topically applied PGE1 was measured by placing the tip of a laser Doppler probe on the bony wall of the basal turn of the cochlea after the middle ear mucosa over the cochlea had been removed in guinea pigs and rats.

Mechanism of leflunomide-induced proliferation of mitochondria in mammalian cells.

Leflunomide (LFM) is an inhibitor of mitochondrial enzyme dihydroorotate dehydrogenase (DHODH) that catalyzes the conversion of dihydroorotate to orotate coupled with the generation of reactive oxygen species (ROS) from mitochondria. We demonstrate here that LFM causes an unrestrained proliferation of mitochondria both in human osteosarcoma cell line 143B cells and rat liver derived RL-34 cells. Increases in the total mass of mitochondria per cell in LFM-treated cells were evidenced by the application of Green FM or 10-n-nonyl acridine orange to flow cytometry, an enhanced replication of mtDNA and electron microscopy.

Activation of caspase-3 is associated with oxidative stress in the hydropic guinea pig cochlea.

The aim of this study was to investigate the involvement of oxidative stress and apoptosis in an animal model of Meniere's disease. Endolymphatic hydrops (ELH) is generally accepted as the decisive histological characteristic of Meniere's disease. Closure of the endolymphatic duct (Kimura's method) was used to induce endolymphatic hydrops in guinea pigs.

The immunohistochemical analysis of pendrin in the mouse inner ear.

Pendred's syndrome (PS) is an autosomal recessive disorder characterized by deafness and goiter, which are caused by mutations in the Pendred's syndrome gene (PDS). PDS encodes a membrane protein named pendrin that is considered to act as an anion transporter. An expression pattern of the PDS ortholog (Pds) mRNA in the auditory and vestibular systems has been reported in mice, and the localization of pendrin has been reported recently.

Imaging of a congenital perilymphatic fistula.

A 7-year-old boy with a history of purulent meningitis and watery rhinorrhea was studied using computed tomography (CT) and magnetic resonance imaging (MRI). He had a common cavity in the left inner ear. With high-resolution heavily T2-weighted MRI, leakage of the inner ear fluid into the middle ear at the oval window area through a congenital perilymphatic fistula could be visualized.

Effects of trolox, locally applied on round windows, on cisplatin-induced ototoxicity in guinea pigs.

Objective: Cisplatin (CDDP), an antitumor agent widely used in the treatment of pediatric solid tumors, has dose-limiting side effects such as ototoxicity and nephrotoxicity. Recently, evidence has been accumulated to demonstrate that these side effects are closely related to oxidative stress. In the present study, we attempted to suppress CDDP-induced ototoxicity in guinea pigs by administering trolox, a water-soluble analogue of alpha-tocopherol which is a natural lipid-soluble antioxidant, locally on round windows.

In vitro activation of extracellular signal-regulated kinase1/2 in the inner ear of guinea pigs.

Growth factors such as vascular endothelial growth factor (VEGF) exert their proliferative properties partly through activation of mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK1/2). Although both VEGF and inactive ERK could be detected in the inner ear of guinea pigs, under normal conditions activated ERK (phospho-ERK) was found only sparely. Cochleae of adult guinea pigs were removed, incubated with VEGF in a carbogen-gased organ-bath for 5, 15, 30 and 60 min (n=6 in each group), fixed with PFA 4%, embedded in paraffin and sectioned, followed by immunohistochemical staining to inactive and active ERK.

Round window membrane in young and aged C57BL/6 mice.

Although there have been many studies on the round window membrane (RWM), little information has been reported about changes in the membrane associated with aging. We have undertaken morphological studies of RWMs using young (7-8 weeks old) and aged (27-29 months old) C57BL/6 mice. The RWM was thinner in mice from the aged group compared with that of the young group.