Development and characterization of a novel specific monoclonal antibody against mink enteritis virus and its antigen epitope analysis.

This study prepared a novel monoclonal antibody (MAb) against mink enteritis parvovirus (MEV) and identified its antigen epitope. The antibody subclass is identified as IgG1, the titers of the MAb is up to 1:1 × 106 and keeps stably after low-temperature storage for 9 months or 11 passages of the MAb cells. The MAb can specifically recognize MEV in the cells in IFA, but not Aleutian disease virus (ADV) or canine distemper virus (CDV). Its antigen epitope was identified as a polypeptide containing 5 key amino acids (378YAFGR382) and the homology in 20 MEV strains, 4 canine parvovirus strains, and 4 feline panleukopenia virus strains was 100%. This study supplies a biological material for developing new methods to detect MEV.

Translocation of telomerase reverse transcriptase coincided with ATP release in postnatal cochlear supporting cells.

The spontaneous bursts of electrical activity in the developing auditory system are derived from the periodic release of adenosine triphosphate (ATP) by supporting cells in the Kölliker's organ. However, the mechanisms responsible for initiating spontaneous ATP release have not been determined. Our previous study revealed that telomerase reverse transcriptase (TERT) is expressed in the basilar membrane during the first postnatal week. Its role in cochlear development remains unclear. In this study, we investigated the expression and role of TERT in postnatal cochlea supporting cells. Our results revealed that in postnatal cochlear Kölliker's organ supporting cells, TERT shifts from the nucleus into the cytoplasm over time. We found that the TERT translocation tendency in postnatal cochlear supporting cells in vitro coincided with that observed in vivo. Further analysis showed that TERT in the cytoplasm was mainly located in mitochondria in the absence of oxidative stress or apoptosis, suggesting that TERT in mitochondria plays roles other than antioxidant or anti-apoptotic functions. We observed increased ATP synthesis, release and activation of purine signaling systems in supporting cells during the first 10 postnatal days. The phenomenon that TERT translocation coincided with changes in ATP synthesis, release and activation of the purine signaling system in postnatal cochlear supporting cells suggested that TERT may be involved in regulating ATP release and activation of the purine signaling system. Our study provides a new research direction for exploring the spontaneous electrical activity of the cochlea during the early postnatal period.

Nickel-Catalyzed Amidation of Aryl Alkynyl Acids with Tetraalkylthiuram Disulfides: A Facile Synthesis of Aryl Alkynyl Amides.

Nickel-catalyzed amidation of aryl alkynyl acids using tetraalkylthiuram disulfides as the amine source is described, affording a series of aryl alkynyl amides in good to excellent yields under mild conditions. This general methodology provides an alternative pathway for the synthesis of useful aryl alkynyl amides in an operationally simple manner, which shows its practical synthetic value in organic synthesis. The mechanism of this transformation was explored through control experiments and DFT calculations.

J Subgroup Avian Leukosis Virus Strain Promotes Cell Proliferation by Negatively Regulating 14-3-3σ Expressions in Chicken Fibroblast Cells.

This study focuses on clarifying the regulation of chicken 14-3-3σ protein on the fibrous histiocyte proliferation caused by ALV-J-SD1005 strain infection. DF-1 cells were inoculated with 102 TCID50 of ALV-J-SD1005 strain; the cell proliferation viability was dramatically increased and 14-3-3σ expressions were dramatically decreased within 48 h after inoculation. Chicken 14-3-3σ over-expression could significantly decrease the cell proliferation and the ratio of S-phase cells, but increase the ratio of G2/M-phase cells in ALV-J-infected DF-1 cells; by contrast, chicken 14-3-3σ knockdown expression could cause the opposite effects. Additionally, chicken 14-3-3σ over-expression could also dramatically down-regulate the expressions of CDK2/CDC2, but up-regulate p53 expressions in the DF-1 cells; in contrast, the knockdown expression could significantly increase the expressions of CDK2/CDC2 and decrease p53 expressions. It can be concluded that chicken 14-3-3σ can inhibit cell proliferation and cell cycle by regulating CDK2/CDC2/p53 expressions in ALV-J-infected DF1 cells. ALV-J-SD1005 strain can promote cell proliferation by reducing 14-3-3σ expressions. This study helps to clarify the forming mechanism of acute fibrosarcoma induced by ALV-J infection.

TRIM25 participates in the fibrous tissue hyperplasia induced by ALV-J infection in chickens by targeting 14-3-3σ protein.

ALV-J-SD1005 strain was subcutaneously inoculated into the necks of 1-day-old HY-Line Brown chickens and caused severe growth retardation, viremia and subcutaneous fibrosarcomas in the necks of all infected chickens from 14 days post inoculation (DPI) to 21 DPI, and also significantly increased the expressions of TRIM25, P53, etc., but significantly decreased the expressions of 14-3-3σ, etc. Overexpression of chicken TRIM25 (chTRIM25) significantly promoted cell proliferation and improved the expressions of P53, CDC2, and CDK2 tumor factors; and significantly inhibited the expression of 14-3-3σ in ALV-J-SD1005-infected DF1 cells; but knockdown of chTRIM25 caused the opposite effects. The results of co-immunoprecipitation (Co-IP) and confocal microscopy confirmed that chTRIM25 can recognize and bind 14-3-3σ protein in ALV-J-SD1005-infected cells, and they were co-located in the cytoplasm. It can be concluded that chTRIM25 participates in the fibrous tissue hyperplasia induced by ALV-J-SD1005 infections in chickens by binding 14-3-3σ protein and regulating the expressions of 14-3-3σ, P53, CDC2, and CDK2.

Preparation and Biochemical Characteristics of a New IgG-Type Monoclonal Antibody against K Subgroup Avian Leukosis Virus.

This study focused on preparing a new IgG-type monoclonal antibody (MAb) against subgroup K avian leukosis virus (ALV-K) and identifying its biochemical characteristics. A specific gene fragment of ALV-K was amplified by polymerase chain reaction and expressed in E. coli. The purified expressed products were inoculated into BALB/c mice to prepare antibody-secreting spleen lymphocytes, and hybridoma cells were obtained after cell fusion of spleen lymphocytes and myeloma cells. A new hybridoma cell line named 30B9, which stably secreted IgG2b-antibody against ALV-K, was screened and contained 98 chromosomes. The MAb secreted by the 30B9 cells could recognize the ALV-K strain but not the ALV-A/B/J strains in an indirect immunofluorescence assay. Seventeen overlapping truncated ALV-K gp85 protein fragments were expressed, and eight peptides were artificially synthesized to analyze the MAb's antigen epitope by Western blot or enzyme-linked immunosorbent assay, and the results showed that the linear epitope was located on the 217-RRNYT-221 of ALV-K gp85 protein. A bioinformatics analysis showed that the epitope has a high antigenicity index, hydrophilicity, and surface accessibility and forms a unique linear spatial structure. Its five amino acids are highly conserved in all published ALV-K strains but are very low in ALV-A/B/J/C/D/E strains. This study provides a new biomaterial for developing specific detection methods against ALV-K.

[Perioperative management of cochlear implantation for CHARGE syndrome].

Objective:To explore the perioperative period characteristics of paediatric cochlear implant recipients of CHARGE syndrome with complex deformities. Methods:Retrospective case series of CHARGE syndrome were included. Radiological results, intraoperative findings, surgical planning and post-operative complications were analyzed. Routine audiometric measurements, speech perception categories and speech intelligibility ratings were performed pre and post-operatively to measure auditory speech rehabilitation outcomes. Results:Five prelingual profoundly deaf children were identified, aged from 14 months to 60 months. All patients had congenital heart disease and underwent surgery before cochlear implantation. Upper airway abnormalities were detected as choanal atresia, laryngomalacia and tracheal stenosis. All ten ears showed cochlear abnormalities（Incomplete partition Ⅱ）, eight of them combined with secretory otitis media and/or middle ear deformity. All patients underwent single side surgery using standard transmastoid facial recess approach. Full insertion of the electrode was achieved in two cochleas, while partial insertion was done in three cochleas. Three ears with absent auditory nerves in MRI showed no response in the neural remote test. All patients had improved audio-speech performance with CAP scores 3.0±0.7 and 3.6±0.9, SIR scores 1.2±0.4 and 1.8±0.8, IT-MAIS scores 18.8±9.1 and 26.2±10.0, MUSS scores 2.2±2.4 and 7.2±8.3 after twelve months and twenty-four months follow up. Conclusion:Cochlear implantation in patients with CHARGE syndrome is a challenge in both its surgical and rehabilitation aspects due to multiple abnormalities. Adequate treatment planning is necessary for safe and effective surgery, including airway structures and intricate temporal bone landmarks.

[Comparative analysis of the hearing of three type reconstruction material in type â ¡ tympanoplasty of 286 cases].

Objective:To compare the effect on hearing of different reconstruction material in type Ⅱ tympanoplasty. Methods:Retrospectively analysis of 286 patients who accepted type Ⅱ tympanoplasty. The air-bone gap of 0.5, 1, 2, 4 kHz was analyzed before and after operation. We compared the hearing change and the complications between each group. Results:In incus group, the manubrium mallei and the head of stapes were connected with shaped incus, PORP group were implanted with PORP during operation, and cartilage group used auricular cartilage to cover the head of stapes. There was no significant difference in 4 kHz air-bone gap（ABG） between the cartilage group and PORP group either before or after the operation （P>0.05）. Air-bone gap of 0.5, 1, 2, 4 kHz of the incus group, and the 0.5, 1, 2 kHz of the cartilage and PORP group were significantly reducedafter the operation（P<0.05）. One patient got severe sensorineural hearing loss in incus group after the operation. The high frequency of bone conduction decreased in 1 patient（2, 4 kHz）.In the incus group, 3 patients had temporary facial paralysis after operation. Incus and cartilage group each have 1 patient with dizziness after the operation. Incus, cartilage and PORP group had 5, 3 and 11 patients with perforation again respectively. There was extrusion occurred in 1 patient of PORP group. Conclusion:Self incus, cartilage and PORP can be used in typeⅡ tympanoplasty, the effect of hearing reconstruction is similar. The first two are more economical, PORP implantation has the lowest technical difficulty and the most widely application, but there is a certain risk of extrusion .

[Analysis of surgical effect on middle ear cholesterol granuloma].

Objective:To evaluate surgical effects on middle ear cholesterol granuloma（CG）. Method:The patients receiving surgery due to middle ear CG were retrospectively analyzed. The choice of operative methods was made according to medical history, endotoscope, pure-tone audiometry and temporal bone CT. Tympanostomy tube（TT） insertion was performed on 12 patients; canal wall up（CWU） tympanoplasty combined with tympanostomy tube was performed on 40 patients, and canal wall down（CWD） tympanoplasty combined with TT on 14 cases. The pre-and postoperative audiometric results（500, 1000, 2000 and 4000 Hz） were evaluated for each patient. Then the average air-bone gap（ABG） was analyzed. Result:One patient had postoperative tube obstruction. One patient who performed only TT insertion recurred. Secretory otitis media occurred in one case undergoing CWU tympanoplasty after removal of the ventilation tube. For TT insertion group, pre-and postoperative ABG levels were （21.25±5.96） dB and （8.85±6.49） dB, respectively（P<0.01）. For CWU+TT group, pre-and postoperative ABG levels were （34.19±10.43） dB and （23.55±12.48） dB, respectively（P<0.01）. For CWD+TT group, pre-and postoperative ABG levels were （36.43±12.11） dB and （25.71±13.50） dB, respectively（P<0.01）. Conclusion:The aim of surgical treatment for middle ear CG includes thorough removal of lesions, improvement of ventilation and drainage of middle ear. Individualized surgical strategy should be adopted according to the patients' conditions. And long-term follow-up should be done after operation.

[Analysis of comorbid psychiatric disorders in patients with chronic otitis media associated tinnitus].

Objective:To analyze the distribution of comorbid psychiatric disorders in patients with chronic otitis media associated tinnitus. Method:The data of patients with chronic otitis media associated tinnitus who accepted surgical treatments from July 2017 to September 2018 were retrospectively analyzed. All patients accepted pure tone audiometry and acoustic conductance examination and were requested to fill the tinnitus history questionnaire, THI, TEQ, SAS, SDS and PSQI scales before operation. When the SAS or/and SDS score ≥50 the patient was judged as having comorbid psychiatric disorders. When the PSQI score>6 the patient was judged as having comorbid sleep disorder, and then all the results were analyzed. Result:Sixty-two patients were included in the study, 43 cases were diagnosed as chronic suppurative otitis media, and 19 cases were diagnosed as middle ear cholesteatoma. The average course of chronic otitis media or middle ear cholesteatoma was（14.38±14.06） years, while the average course of tinnitus was（8.39±11.69） years. There were 32 cases with mild to moderate tinnitus（gradeⅠ-Ⅱ）（51.61%） and 30 cases with moderate to severe tinnitus（grade Ⅲ-Ⅴ）（48.39%）. Before operation, there were 4 cases（6.45%） with normal hearing, 38 cases（61.29%） with conductive hearing loss, and 20 cases（32.36%） with mixed hearing loss. There was no significant difference in tinnitus severity between different hearing loss degrees and types（P>0.05）. The average SAS score was 45.10±11.61, and the average SDS score was 43.48±14.67, both higher than the normal modulus（30 points）, among which 27 cases（44.00%） comorbid psychiatric disorders. The THI score in patients with comorbid psychiatric disorders（57.85±21.1） was significantly higher than that in patients without comorbid psychiatric disorders（29.2±17.39）（P<0.05）. The PSQI score in patients with comorbid psychiatric disorders（8.86±3.47） was significantly higher than that of those without comorbid psychiatric disorders（6.24±2.54）（P<0.05）. Fifty-three patients were followed up for 0.5 to 1.8 years after operation, and in 43 cases the tinnitus was reduced or disappeared after operation（the effective rate was 81.13%）. There were no significant difference between patients in tinnitus relief group and those in tinnitus without relief group in age, sex, course of the disease, type of the disease, with or without comorbid psychiatric disorders and/or sleep disorder, postoperative hearing improvement. Conclusion:Comorbid psychiatric disorders are common in patients with chronic otitis media associated tinnitus and the tinnitus in patients with comorbid psychiatric disorders is significantly more serious than that those without. For the treatment of chronic otitis media associated tinnitus, besides surgery, the complications such as psychiatric and sleep disorders and so on should be evaluated and treated accordingly.

[The effect of one-stage tympanoplasty for stapes fixation with tympanosclerosis].

Objective:To evaluate hearing outcome and complications of one-stage tympanoplasty in patients with stapes fixation due to tympanosclerosis. Method:59 patients（sixty-one ears） underwent one-stage tympanoplasty for stapes fixation due to tympanosclerosis were retrospectively analyzed. Stapes fixation due to tympanosclerosis were proved during the surgery in these patients diagnosed with chronic otitis media. For all the patients, tympanosclerotic plaques around stapes were removed for stapes mobilization. Then the ossicular chain was rebuilt by autogenous incus or PORP. The pre-and post-operative audiometric results（500 Hz, 1 kHz, 2 kHz and 4 kHz） were evaluated for each patient. Improvement of pure-tone average more than 10 dB postoperatively were accepted as success criteria. Result:Complications included temporary facial paralysis（1/61）, temporary vertigo（2/61）, mild elevation in bone conduction thresholds（2/61） and delayed healing of tympanic membrane（1/61）. Postoperative（1 and 3 months） bone conduction thresholds improved at frequencies of 1 and 2 kHz（P<0.01）. Postoperative（1 and 2 years） air conduction thresholds improved at all frequencies（P<0.01 or P<0.05）. A gain ≥10 dB in pure-tone average was found in 44（72.13%） patients at 1 year after surgery. The air conduction levels were significantly improved in both autogenous incus and PORP groups（P<0.01）. There was no difference about success rate between these two groups（P>0.05）. Conclusion:For patients with stapes fixation due to tympanosclerosis, one-stage tympanoplasty can improve hearing threshold though ossicular chain reconstruction and stapes release. The major complications such as facial paralysis and sensorineural hearing loss should be avoided by delicate surgical operation.

Caspase inhibitor z-VAD-FMK increases the survival of hair cells after Actinomycin-D-induced damage in vitro.

Actinomycin-D (Act-D) is a highly effective chemotherapeutic agent that induces apoptosis in systemic tissues. Act-D combined with other chemotherapeutic agents exhibits ototoxic effects and causes hearing impairment. To investigate the potential toxic effects of Act-D in the inner ear, we treated cochlear organotypic cultures with varying concentrations of Act-D for different durations. For the first time, we found that Act-D specifically induced HC loss and apoptosis in a dose- and time-dependent manner but not neuronal degeneration. Co-treatment with benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (z-VAD-FMK), a pan cysteine protease inhibitor, significantly reduced HC loss and apoptosis induced by Act-D, indicating increased cell survival. Taken together, Act-D exposure has ototoxic effects on the auditory system, while z-VAD-FMK prevents Act-D-induced hair cell damage.

Costunolide induces apoptosis and inhibits migration and invasion in H1299 lung cancer cells.

Costunolide being a sesquiterpene lactone, is known to have anticancer properties. The present study investigated the anticancer effects of costunolide against the H1299 human non­small­cell lung cancer (NSCLC) cell line. Inhibition of cell viability by costunolide was assessed via a MTT assay. Furthermore, the apoptotic rate was detected using Annexin V/propidium iodide labeling. A colony forming cell assay was performed to investigate the antiproliferative effects of costunolide. Wound healing and Transwell assays were performed to determine the inhibitory effects of costunolide on migration and invasion, respectively. Western blot analysis was undertaken to determine protein expression, and reverse transcription­quantitative PCR was performed to assess mRNA expression levels. The results demonstrated that costunolide inhibited the viability of H1299 cells, with a half maximal inhibitory concentration value of 23.93±1.67 µM and induced cellular apoptosis in a dose­dependent manner. Furthermore, the colony formation, migrative and invasive abilities of the H1299 cells were inhibited in a dose­ or time­dependent manner. The protein expression levels of E­cadherin increased and those of N­cadherin decreased following treatment with costunolide, which suggested that costunolide inhibited epithelial­to­mesenchymal transition. The mRNA levels of B­Raf, E­cadherin, N­cadherin, integrins α2 and ß1, as well as matrix metalloproteinases 2 were also found to be regulated costunolide. These findings indicate the potential of costunolide in the treatment of NSCLC.

ATP depletion induced cochlear hair cells death through histone deacetylation in vitro.

Previous studies have shown histone modifications being present in cochlear hair cells in animal models of hearing loss. Our past studies have shown that ATP depletion, histone deacetylase (HDAC) upregulation, and histone deacetylation occur in cochlea after noise exposure, and these are linked to hair cell death. Whether ATP depletion correlates with the expression level of HDACs and acetylation of histones is still unknown. In this study, we investigated the changes in the expression of HDACs and the level of histone acetylation in cochlear hair cells using an ATP-depleted explant culture of mouse organ of Corti. We found that the expression of HDAC3 and HDAC6 increased and hair cells were lost after oligomycin A (OA) treatment. Meanwhile, the acetylation level of histone H2B reduced. However, when oligomycin was combined with an HDAC inhibitor, trichostatin A (TSA), the acetylation level of histone H3 was restored. Moreover, combined treatment of oligomycin and TSA or sodium butyrate (NaB) attenuated oligomycin-induced cochlear hair cell loss. In conclusion, our results indicated that ATP depletion led to histone deacetylation and eventually resulted in hair cell death.

miR-182 prevented ototoxic deafness induced by co-administration of kanamycin and furosemide in rats.

Ototoxic drugs may induce auditory sensory hair cell loss and permanent deafness; however, there is still no effective treatments or prevention strategies for this side effect. A recent study found that microRNA182 (miR-182) protected cochlear hair cells from ototoxic drug-induced apoptosis in vitro. However, it remains unclear whether miR-182 can protect drug-induced deafness in vivo. In this study, we overexpressed cochlear miR-182 in Sprague-Dawley rats by trans-round window niche delivery of miR-182 mimics. The rats subsequently received intraperitoneal injections of kanamycin and furosemide to induce acute cochlear outer hair cell death and permanent deafness. Auditory brainstem response tests showed that miR-182 attenuated permanent threshold shifts. Consistent with this result, miR-182 reduced the loss of outer hair cells and missing stereocilia. miR-182 treatment also increased the level of phosphoinositide-3 kinase regulatory subunit p85α in the outer hair cells after co-administration of kanamycin and furosemide. Our findings suggest that miR-182 has powerful protective potential against ototoxic drug-induced acute auditory sensory hair cell loss and permanent deafness.

[Effect of tympanoplasty on wet ear with different mucosal status of tympanic cavity].

Objective:A retrospective analysis of audiologic outcome and graft take rate on post-tympanoplasty with different middle ear mucosal conditions in wet ear. Method:According to the characteristics of middle ear mucosal condition and residual eardrum, 80 cases with wet ear of chronic suppurative otitis media were divided into the hydrocele group, the swelling group and the granulation group. The factors in different groups, including gender, age, disease course, sides, size and location of perforations, destruction of ossicular chain and reconstruction methods were analyzed. Moreover, postoperative hearing improvement and graft take rate were compared among the three groups. Result:There was no significant difference in gender, age, disease course, sides, size and location of perforations among the hydrocele group, the swelling group and the granulation group （P>0.05）. Overall, the postoperative average Air-Bone Gaps（ABG） were reduced in all wet ear patients after surgery （P<0.01）. The ABG was decreased from （25.5 ± 10.8） dB to（15.4 ± 9.4） dB in the hydrocele group, and decreased from （27.6 ± 8.7） dB to （15.2 ± 9.6） dB in the swelling group, and from （29.5 ± 7.7） dB to （17.2 ± 17.2） dB in the granulation group. The graft take rates were 90.0% in totally. There were no significant difference in graft take rates among the three groups, and 84.6% in the hydrocele group, 93.3% in the swelling group and 100.0% in the swelling group（P>0.05）. Conclusion:Wet ear is not an absolute contraindication of tympanoplasty for chronic suppurative otitis media. Whether there was effusion, swelling or granulomatous hyperplasia in the tympanoplasty, the patients'hearing improved significantly after tympanoplasty, and the healing rate of the tympanoplasty did not decrease. Further basic and clinical studies are needed to standardize the timing of wet ear surgery, clarify the operative contraindication and elucidate the pathophysiological mechanism of eardrum healing.

Improved Photovoltaic Effect of p-i-n Structured BiFeO3 Film Deposited by Radio-Frequency Magnetron Sputtering.

Pure phase polycrystalline BiFeO3 film was deposited onto FTO substrate by RF magnetron sputtering method. SEM result shows that BiFeO3 film has the obvious porosity and large clusters which lead to the poor ferroelectric and photovoltaic properties in FTO/BiFeO3/Ag device. However, these properties are improved in p-i-n structured FTO/TiO2/BiFeO3/HTM/Ag device by incorporating the electron and hole transport materials. The hysteresis loop measurement demonstrates the excellent ferroelectric property with large remnant polarization (2Pr = 180 µC/cm²) and low leakage current. The J-V curve shows the short-circuit current density is dozens of times larger than that of FTO/BiFeO3/Ag device. Moreover, the photovoltaic output depends on the poling field where the positive poling improves the short-circuit current density to -85 µA/cm2 and the negative poling reduces both the photocurrent and photovoltage. It is believed that the ferroelectric polarization plays a dominant role in the photovoltaic effect.

Preparation of a new monoclonal antibody against subgroup A of avian leukosis virus and identifying its antigenic epitope.

This study focuses on preparing the monoclonal antibody (MAb) against subgroup A of avian leukosis virus (ALV-A) and identifying its antigenic epitope. The ALV-A gp85 gene with a size of 1005bp was amplified and expressed into a recombinant protein with a size of 46KD in E.coli. The products expressed after purification were inoculated into BALB/c mice for preparing antibody-secreting splenic lymphocytes and further obtaining hybridoma cells. Finally, one new hybridoma cell (A18GH) secreting MAb against ALV-A was screened, and the MAb was able to detect ALV-A/K strains in an indirect immunofluorescence assay (IFA), but not ALV-B/J strains. A total of 14 overlapping truncated ALV-A gp85 protein segments were expressed and eight peptides containing different antigenic amino acids were artificially synthesized for analyzing the antigenic epitope of the MAb using a western blot or an ELISA, and the results indicate that the antigenic epitope consists of seven amino acids within the 146-ATRFLLR -152 region of the ALV-A gp85 protein. A biological information analysis shows that the antigenic epitope has a high antigenic index and develops a curved linear spatial structure. Further, its 7 amino acids are completely within the 17 representative ALV-A strains, 4 are within the 11 ALV-K strains, and fewer are within the ALV-B/J/E strains. This study will significantly assist in a further understanding of the protein structure and function of ALV-A, and in the establishment of specific ALV-A detection methods.

Inhibition of DHCR24 increases the cisplatin-induced damage to cochlear hair cells in vitro.

Hearing loss is a common sensory disorder that affects more than 360 million people worldwide, and is primarily caused by the loss of hair cells (HCs). Ototoxic drugs, viral infections, genetic predisposition, aging or noise all damage HCs. 3ß-hydroxysteroid-Δ24 reductase (DHCR24), one enzyme in the cholesterol biosynthetic pathway, is involved in inflammation, oxidative stress and neuroprotection. However, researchers have not determined whether DHCR24 is present in the cochlea and the mechanism by which it exerts its regulatory effect on HC loss. In the present study, we analyzed DHCR24 expression in the postnatal day 1 (P1) rat cochlea and found that DHCR24 was localized in HCs of the organ of Corti. Next, exposure to cisplatin caused HC loss in cochlear organotypic cultures. Then, we inhibited DHCR24 expression with U18666A and observed significantly increased cisplatin-induced damage of cochlear HCs. These findings were consistent with the observed increase in DHCR24 expression in response to cisplatin treatment, and U18666A significantly decreased DHCR24 expression. Finally, DHCR24 inhibition increased the levels of reactive oxygen species and cleaved caspase-3 after cisplatin-induced injury. Collectively, DHCR24 may play a significant role in regulating auditory function and potentially represents a new therapeutic target for the treatment of cisplatin-induced ototoxicity.