Transcription of cytochrome P450 46A1 in NIH3T3 cells is negatively regulated by FBS.

Extracellular administration of side-chain oxysterols, such as 24S-hydroxycholesterol (24S-HC), 27-hydroxycholesterol (27-HC) and 25-hydroxycholesterol (25-HC) to cells suppresses HMG-CoA reductase (Hmgcr) and CTP:phosphoethanolamine cytidylyltransferase (Pcyt2) mRNA levels. Oxysterols are enzymatically produced in cells from cholesterol by cytochrome P450 46A1 (Cyp46A1), Cyp27A1, Cyp3A11 and cholesterol 25-hydroxylase (Ch25h). We analyzed which of these oxysterol-producing enzymes are expressed in NIH3T3 cells and found that only Cyp46A1 was expressed. When Cyp46A1 was overexpressed in NIH3T3 cells, intrinsic oxysterols increased in the order 24S-HC > 25-HC > 27-HC. We investigated the mechanism regulating the production of endogenous oxysterols in NIH3T3 cells by Cyp46A1 and found that the mRNA, relative protein levels and enzymatic activity of Cyp46A1, and the amounts of 24S-HC, 25-HC and 27-HC significantly increased under serum-starved conditions, and these increases were suppressed by FBS supplementation. The aqueous phase of FBS obtained by the Bligh & Dyer method significantly suppressed Cyp46A1 mRNA levels. Fractionation of the aqueous phase by HPLC and analysis of the inhibiting fractions by nanoLC and TripleTOF MS/MS identified insulin-like factor-II (IGF-II). Cyp46A1 mRNA levels in serum-starved NIH3T3 cells were significantly suppressed by the addition of IGFs and insulin and endogenous oxysterol levels were decreased. CYP46A1 mRNA levels in the T98G human glioblastoma cell line were also increased by serum starvation but not by FBS supplementation, and the aqueous phase did not inhibit the increase. These results suggest that mRNA levels of Cyp46A1 are regulated by factors in FBS.

Postoperative Course of Pars Flaccida Cholesteatoma Patients With Habitual Sniffing.

OBJECTIVE: To investigate the effects of habitual sniffing on the postoperative course of pars flaccida cholesteatoma. STUDY DESIGN: Retrospective case series study. SETTING: University hospital. PATIENTS: Forty-nine patients (53 ears) with pars flaccida cholesteatoma and history of habitual sniffing before the initial operation. INTERVENTIONS: Patients were divided into a "sniffing cessation group" characterized by sniffing cessation and a "continual sniffing group" characterized by continuation of sniffing despite instructions for conscious cessation. MAIN OUTCOME MEASURES: Hearing level, tympanic membrane findings, tympanograms, mastoid cell development before the operation, and pneumatization 1 year postoperatively. RESULTS: The sniffing cessation and continual sniffing groups comprised 35 patients (38 ears) and 14 patients (15 ears), respectively. The average postoperative hearing was slightly better in the continual sniffing group. In the sniffing cessation group, retractions were evident in significantly fewer cases. Retractions were observed in all continual sniffing group cases, with a high percentage of severe retractions, wherein the bottom was not visible. Type A tympanogram was predominant in the sniffing cessation group. Mastoid cell development was not significantly different between the two groups. Satisfactory pneumatization was significantly more common in the sniffing cessation group (Fisher's exact test, p < 0.005). CONCLUSION: Conscious cessation of the sniffing habit could reduce the risk of postoperative retraction and improve pneumatization in patients with pars flaccida cholesteatoma. The presence or absence of the sniffing habit after surgery is a defining factor in postoperative prognosis (retraction, recurrence), and may be a determinant for decisions regarding surgical approach.

Efficacy of a silicone plug for patulous eustachian tube: A prospective, multicenter case series.

OBJECTIVES/HYPOTHESIS: To report the efficacy and safety of transtympanic plugging of the eustachian tube (ET) using a silicone plug (Kobayashi plug) for chronic patulous ET (PET). STUDY DESIGN: Prospective and multicenter trial conducted in which 30 PET patients were resistant to at least 6 months of conservative treatment. METHODS: The efficacy and safety of 28 and 27 patients, respectively, were analyzed. All patients fulfilled inclusion and exclusion criteria. The primary end point used the patulous eustachian tube handicap inventory-10 (PHI-10), and the secondary end point used ET function tests such as sonotubometry, tubo-tympano-aerodynamic-graphy, and respiratory movement of the tympanic membrane and auscultation of voice sounds transmitted from the nose through the ET to the external auditory canal at 3months after surgery. RESULTS: PHI-10 scores were 34.4 ± 4.2, 6.4 ± 9, and 5.7 ± 8.6 at screening, and 3 and 6 months after surgery. Twenty-three cases (82.1%, 95% confidence interval: 63.1%-93.9%) were judged as successes. There were five cases (17.2%) of middle ear effusion, four cases (13.8%) of tympanic membrane perforation, and one case of tinnitus due to surgery to remove the plug. No severe or life-threatening complications were found. CONCLUSIONS: This study revealed the efficacy and safety of silicone plug insertion for severe PET patients. LEVEL OF EVIDENCE: 2 Laryngoscope, 130:1304-1309, 2020.

Characterization of glycerophosphodiesterase 4-interacting molecules Gαq/11 and Gß, which mediate cellular lysophospholipase D activity.

We previously purified lysophospholipase D (lysoPLD), which hydrolyzes lysophosphatidylcholine (lysoPC) to lysophosphatidic acid (LPA), from rat brain and identified the heterotrimeric G protein subunits Gαq and Gß1 in the lysoPLD active fractions. Tag-affinity purified Gαq exhibits lysoPLD activity but a mutant that affected cellular localization or interaction with the Gß subunit reduced lysoPLD activity. Size exclusion chromatography revealed that active lysoPLD is a much higher molecular mass complex than is heterotrimeric G protein, suggesting the presence of other components. Liquid chromatography-tandem mass spectrometry of lysoPLD purified from rat brain identified glycerophosphodiesterase 4 (GDE4), recently reported as lysoPLD, in the same fraction as G proteins. The overexpressed and tag-purified Gαq fractions, which exhibit lysoPLD activity, contained GDE4. Exogenously expressed GDE4 was co-immunoprecipitated with endogenous Gαq and Gß and exhibited high lysoPLD activity. The results of confocal microscopy and cell fractionation experiments indicated that exogenously expressed GDE4 in cells mainly localized at the endoplasmic reticulum and partially co-localized with Gαq protein at the plasma membrane. Proteinase K protection assay results suggested that the catalytic domain of GDE4 faces the lumen/extracellular space. Mutations at the conserved amino acids in the C-terminus cytoplasmic regions amongst GDE1, 4 and 7, dramatically suppressed GDE4 enzyme activities. When both the Gαq and Gα11 genes in Neuro2A cells were disrupted using the CRISPR-Cas9 system, endogenous lysoPLD activity was partially reduced but rescued by overexpression of Gαq. These results suggest that GDE4 is a new effector of G protein signaling that produces bioactive phospholipid LPA and/or modulates membrane homeostasis.

Localization of megalin in rat vestibular dark cells and endolymphatic sac epithelial cells.

CONCLUSION: Megalin immunoreactivity was observed in kidney proximal tubule cells, vestibular dark cells, and epithelial cells of the endolymphatic sac. Endocytic mechanisms appear to differ between the endolymphatic sac and proximal tubule cells. We speculate that megalin is secreted by a certain type of cell into the endolymphatic space, and is then absorbed from the endolymphatic space by another type of cell to maintain endolymphatic sac homeostasis. OBJECTIVES: We previously detected megalin immunoreactivity in the rat cochlear duct. Megalin may be involved in endocytosis in the vestibular organ and endolymphatic sac. To examine this possibility, we extended our immunocytochemical investigation to the rat inner ear cells with special attention to vestibular dark cells and endolymphatic sac. MATERIALS AND METHODS: We observed immunoreactivity of megalin under light and electron microscopy. The primary antibody was rabbit polyclonal antibody that had been raised against rat immunoaffinity-purified megalin. RESULTS: The luminal membrane and subapical area of dark cells in the semicircular canal were immunolabeled. The stainable substance in the endolymphatic space was strongly stained. The cytoplasm of epithelial cells was also stained in various patterns.

Ultrastructural co-localization of cochlin and type II collagen in the rat semicircular canal.

Cochlin and type II collagen are major constituents of the inner ear extracellular matrix. To investigate the morphological relation of cochlin and type II collagen in the rat semicircular canal, immuno-electronmicroscopic analysis was performed using the post-embedding immunogold method. Immunolabeling for cochlin was detected in the fibrillar substance underlying the supporting epithelium of the sensory cells and beneath the epithelial cells facing the endolymph in the semicircular canals. Immunolabeling for type II collagen was observed in the same fibrillar substance in the subepithelial area. The co-localization of cochlin and type II collagen in the fibrillar substance in the subepithelial area indicate that cochlin may play a role in the structural homeostasis of the vestibule acting in concert with the fibrillar type II collagen bundles.

Dual-subtype FIV vaccine (Fel-O-Vax FIV) protection against a heterologous subtype B FIV isolate.

Vaccine trials were undertaken to determine whether the Fel-O-Vax FIV, a commercial dual-subtype (subtypes A and D) feline immunodeficiency virus (FIV) vaccine, is effective against a subtype B FIV isolate. Current results demonstrate the Fel-O-Vax FIV to be effective against a subtype B virus, a subtype reported to be the most common in the USA.