Animal Models of Middle Ear Cholesteatoma

Middle ear acquired cholesteatoma is a pathological condition associated with otitis media, which may be associated with temporal bone resorption, otorrhea and hearing loss, and occasionally various other complications. Cholesteatoma is characterized by the enhanced proliferation of epithelial cells with aberrant morphologic characteristics. Unfortunately, our understanding of the mechanism underlying its pathogenesis is limited. To investigate its pathogenesis, different animal models have been used. This paper provides a brief overview of the current status of research in the field of pathogenesis of middle ear acquired cholesteatoma, four types of animal models previously reported on, up-to-date cholesteatoma research using these animal models, our current studies of the local hybrid ear model, and the future prospect of new animal models of middle ear cholesteatoma

APC/C–Cdc20-mediated degradation of cyclin B participates in CSF arrest in unfertilized Xenopus eggs

AbstractIn vertebrates, unfertilized eggs are arrested at meiotic metaphase II (meta-II) by cytostatic factor (CSF), with Cdc2 activity maintained at a constant, high level. CSF is thought to suppress cyclin B degradation through the inhibition of the anaphase-promoting complex/cyclosome (APC/C)-Cdc20 while cyclin B synthesis continues in unfertilized eggs. Thus, it is a mystery how Cdc2 activity is kept constant during CSF arrest. Here, we show that the APC/C–Cdc20 can mediate cyclin B degradation in CSF-arrested Xenopus eggs and extracts, in such a way that when Cdc2 activity is elevated beyond a critical level, APC/C–Cdc20-dependent cyclin B degradation is activated and Cdc2 activity consequently declines to the critical level. This feedback control of Cdc2 activity is shown to be required for keeping Cdc2 activity constant during meta-II arrest. We have also shown that Mos/MAPK pathway is essential for preventing the cyclin B degradation from inactivating Cdc2 below the critical level required to sustain meta-II arrest. Our results indicate that under CSF arrest, Mos/MAPK activity suppresses cyclin B degradation, preventing Cdc2 activity from falling below normal meta-II levels, whereas activation of APC/C–Cdc20-mediated cyclin B degradation at elevated levels of Cdc2 activity prevents Cdc2 activity from reaching excessively high levels

Tree-Like Features Formed on Photoelectrochemically etched n-GaN surfaces ―Revelation of threading dislocations in GaN―

Electrochemical etching behavior of n-type GaN films grown on sapphire has been studied under UV (λ=325 nm) light illumination. As the cases for photoelectrochemical etching of n-type GaAs and InP, three different features appear on etched n-GaN surfaces depending on current density for etching; a high density (10^10 cm^<-2>) of tree-like protrusions at a lower c-urrent density, a relatively flat surface at an intermediate current density, and peeling of the film from the substrate at a higher current density. From the shape and the density of tree-like protrusions, in addition to the analogy of these results with those for n-type GaAs and InP, it is reasonable to conclude that tree-like protrusions formed at a low current density are due to threading dislocations involved in n-GaN films. Thus, the photoelectrochemical etching is found to become a convenient method to detect dislocations in n-type III nitride materials

Mutations in N-terminal flanking region of blue light-sensing light-oxygen and voltage 2 (LOV2) domain disrupt its repressive activity on kinase domain in the Chlamydomonas phototropin.

Phototropin is a light-regulated kinase that mediates a variety of photoresponses such as phototropism, chloroplast positioning, and stomata opening in plants to increase the photosynthetic efficiency. Blue light stimulus first induces local conformational changes in the chromophore-bearing light-oxygen and voltage 2 (LOV2) domain of phototropin, which in turn activates the serine/threonine (Ser/Thr) kinase domain in the C terminus. To examine the kinase activity of full-length phototropin conventionally, we employed the budding yeast Saccharomyces cerevisiae. In this organism, Ser/Thr kinases (Fpk1p and Fpk2p) that show high sequence similarity to the kinase domain of phototropins exist. First, we demonstrated that the phototropin from Chlamydomonas reinhardtii (CrPHOT) could complement loss of Fpk1p and Fpk2p to allow cell growth in yeast. Furthermore, this reaction was blue light-dependent, indicating that CrPHOT was indeed light-activated in yeast cells. We applied this system to a large scale screening for amino acid substitutions in CrPHOT that elevated the kinase activity in darkness. Consequently, we identified a cluster of mutations located in the N-terminal flanking region of LOV2 (R199C, L202L, D203N/G/V, L204P, T207I, and R210H). An in vitro phosphorylation assay confirmed that these mutations substantially reduced the repressive activity of LOV2 on the kinase domain in darkness. Furthermore, biochemical analyses of the representative T207I mutant demonstrated that the mutation affected neither spectral nor multimerization properties of CrPHOT. Hence, the N-terminal flanking region of LOV2, as is the case with the C-terminal flanking Jα region, appears to play a crucial role in the regulation of kinase activity in phototropin

Reconstruction of the P2X2 Receptor Reveals a Vase-Shaped Structure with Lateral Tunnels above the Membrane

SummaryIn response to the intercellular messenger ATP, P2X receptors transfer various sensory information, including pain. Here we have reconstructed the structure of the P2X2 receptor at 15 Å resolution from more than 90,000 particle images, taken with a cryo-electron microscope equipped with a helium-cooled stage. This three-dimensional depiction, presumably in a closed state, revealed an elongated vase-shaped structure 202 Å in height and 160 Å in major diameter. The extracellular and transmembrane domains present a two-layered structure, in which a sparse outer layer surrounds a pore-forming inner density. The decreased diameter of a putative ion-conducting pathway at the middle of the membrane was considered to be the narrowest part of the pore, which has been predicted from electrophysiological studies. The sparse, extended structure of the P2X2 receptor indicates a loose assembly of subunits, which could be a basis for the activation-dependent pore dilation of P2X receptors

Safety and Pain-relief Efficacy of Urethral Catheter with Local-anesthetic Injection Port

Article信州医学雑誌 65(6): 355-359(2017)journal articl

一九九五年以降の村上春樹文学の変遷 : ―〈コミットメント〉と〈継承〉の相補性―

中央⼤学博士(文学)【学位授与の要件】中央大学学位規則第4条第1項 【論文審査委員主査】宇佐美　毅(中央大学文学部教授) 【論文審査委員副査】山下　真史(中央大学文学部教授),高橋　慎也(中央大学文学部教授),千田　洋幸(東京学芸大学教育学部教授)doctoral thesi

村上春樹論―『1Q84』における〈コミットメント〉の到達点と〈継承〉の可能性―

application/pdf査読付論文departmental bulletin pape

Improved HPLC determination of acidic opines by phenylisothiocyanate derivatization and its application to marine animals.

We present here a reliable and sensitive method for the determination of acidic opines such as meso-alanopine, beta-alanopine, tauropine and strombine in biological samples. Interfering primary amino acids were eliminated by reaction with o-phthalaldehyde, and the derivatized compounds were passed through Sep-Pak Plus PS-1 cartridges. The acidic opines were recovered by flushing the cartridges with water, then determined by high performance liquid chromatography after a second derivatization with phenylisothiocyanate. All 4 acidic opines were detected within 30 min. This method ensured good separation and guaranteed almost full recovery of all acidic opines. This method was applied to analyze opines in marine animals and to test whether opines are metabolized in the livers of the rat and fish.</p