Ephrins and Ephs in cochlear innervation and implications for advancing cochlear implant function.

Objectives/hypothesis: Determine if the neuronal pathfinding cues resulting from Eph/ephrin interaction in the inner ear play a role in establishing the tonotopic innervation of the cochlea.

Study Design: Protein expression of Ephs and ephrins was evaluated in the inner ear of mice and chicks. Subsequently, in vitro, in vivo, and functional electrophysiologic studies were performed to indicate that Ephs and ephrins play a role regulating the normal innervation patterns in the mouse inner ear.

Ototopic applications of povidone iodine/dexamethasone in the rat.

Hypothesis: Repeated applications of low-concentration povidone iodine (PI) combined with dexamethasone (Dex) through a tympanic membrane ventilation tube will not cause ototoxic changes in the rat.

Background: Otitis externa (OE) and acute otitis media (AOM) are 2 of the most common otologic disorders requiring outpatient antibiotic treatment. The development of topical treatments that are easy to administer would help to limit systemic exposure to antibiotics in these patients.

Effects of cochlear drilling with Piezosurgery Medical device in rats.

Objectives/hypothesis: Drilling on the otic capsule for cochleostomy should be less traumatic to the cochlea with the Piezosurgery Medical device (PZ) than with a standard diamond drill (DD). "Soft" cochleostomy is used for preservation of residual hearing in cochlear implant patients. PZ drilling can be used for accurate cochleostomy placement with minimal soft-tissue damage and may be superior for atraumatic drilling on the cochlea, as compared with a DD.

Comparison of systemic and otic administration of ofloxacin.

Objectives: To assess the feasibility of delivering ofloxacin across the intact tympanic membrane; to compare middle ear bioavailability of ofloxacin after otic and systemic administrations; to determine distribution of otically delivered ofloxacin to other tissues.

Study Design: A prospective, controlled animal study.

Methods: Rats underwent surgery wherein the middle ear cavity was opened and filled with saline.

Ototoxicity of topical azithromycin solutions in the guinea pig.

Objective: To investigate possible ototoxic effects of topical azithromycin (AZ) in the guinea pig.

Design: A prospective, controlled animal study.

Setting: The University of Texas Southwestern Medical Center at Dallas.

Relative structural and functional roles of multiple deubiquitylating proteins associated with mammalian 26S proteasome.

We determined composition and relative roles of deubiquitylating proteins associated with the 26S proteasome in mammalian cells. Three deubiquitylating activities were associated with the 26S proteasome: two from constituent subunits, Rpn11/S13 and Uch37, and one from a reversibly associated protein, Usp14. RNA interference (RNAi) of Rpn11/S13 inhibited cell growth, decreased cellular proteasome activity via disrupted 26S proteasome assembly, and inhibited cellular protein degradation.

Apoptosis in cerebellar granule neurons is associated with reduced interaction between CREB-binding protein and NF-kappaB.

Cerebellar granule neurons undergo apoptosis when switched from medium containing depolarizing levels of potassium (high K+ medium, HK) to medium containing low K+ (LK). NF-kappaB, a ubiquitously expressed transcription factor, is involved in the survival-promoting effects of HK. However, neither the expression nor the intracellular localization of the five NF-kappaB proteins, or of IkappaB-alpha and IkappaB-beta, are altered in neurons primed to undergo apoptosis by LK, suggesting that uncommon mechanisms regulate NF-kappaB activity in granule neurons.

Definition of additional functional ligands for Ly49I(B6) using FVBLy49I(B6) transgenic mice and B6 natural killer cell effectors.

Background: Natural killer (NK) cells use inhibitory Ly49 receptors to differentiate self from foreign cells based on interactions with major histocompatibility (MHC) class I molecules. Inhibitory receptors may recognize multiple MHC class I molecules. Studies to define ligands for the Ly49 receptors are complicated by the fact that receptors are expressed in overlapping subsets on NK cells.