miR-144 affects the immune response and activation of inflammatory responses in Cynoglossus semilaevis by regulating the expression of CsMAPK6.

MicroRNAs are increasingly recognized for their pivotal role in the immune system, yet the specific regulatory functions of fish-derived microRNAs remain largely unexplored. In this research, we discovered a novel miRNA, Cse-miR-144, in the Chinese tongue sole (Cynoglossus semilaevis), characterized by a 73-base pair precursor and a 21-nucleotide mature sequence. Our findings revealed that the expression of Cse-miR-144 was notably inhibited by various Vibrio species. Utilizing bioinformatics and dual-luciferase assay techniques, we established that the pro-inflammatory cytokine gene CsMAPK6 is a direct target of Cse-miR-144. Subsequent in vitro and in vivo western blotting analyses confirmed that Cse-miR-144 can effectively reduce the protein levels of CsMAPK6 post-transcriptionally. Moreover, CsMAPK6 is known to be involved in the activation of the Nuclear Factor kappa-light-chain-enhancer of activated B cells (NF-kB). Additional investigations using qPCR and ELISA demonstrated that suppression of Cse-miR-144 leads to an upsurge in the liver mRNA levels of various immune genes (including MYD88, TRAF6, NF-κB, TRAF2, TRAF3, and TNF), alongside a marked increase in the production and secretion of pro-inflammatory cytokines (IL-1ß, IL-6, and IL-8) in the bloodstream of C. semilaevis. These findings collectively underscore the potential of Cse-miR-144 as a key inhibitor of CsMAPK and its crucial role in modulating the immune and inflammatory responses in teleost fish. Compared to the siRNA, miRNA is a better tool in controlling the expression of target gene with a lower cost.

Cisplatin ototoxicity mechanism and antagonistic intervention strategy: a scope review.

Cisplatin is a first-line chemotherapeutic agent in the treatment of malignant tumors with remarkable clinical effects and low cost. However, the ototoxicity and neurotoxicity of cisplatin greatly limit its clinical application. This article reviews the possible pathways and molecular mechanisms of cisplatin trafficking from peripheral blood into the inner ear, the toxic response of cisplatin to inner ear cells, as well as the cascade reactions leading to cell death. Moreover, this article highlights the latest research progress in cisplatin resistance mechanism and cisplatin ototoxicity. Two effective protective mechanisms, anti-apoptosis and mitophagy activation, and their interaction in the inner ear are discussed. Additionally, the current clinical preventive measures and novel therapeutic agents for cisplatin ototoxicity are described. Finally, this article also forecasts the prospect of possible drug targets for mitigating cisplatin-induced ototoxicity. These include the use of antioxidants, inhibitors of transporter proteins, inhibitors of cellular pathways, combination drug delivery methods, and other mechanisms that have shown promise in preclinical studies. Further research is needed to evaluate the efficacy and safety of these approaches.

A Drimane Meroterpenoid Borate as a Synchronous Ca+ Oscillation Inhibitor from the Coral-Associated Fungus Alternaria sp. ZH-15.

Territrem F (1), a drimane meroterpenoid bearing a unique borate ring system, was isolated together with its diol precursor territrem B (2) from the fungus Alternaria sp. ZH-15 associated with the soft coral Lobophytum crassum collected in the South China Sea. The structure of the new compound was elucidated by spectroscopic analysis and an X-ray single-crystal diffraction study, representing a new type of boron-containing natural product. Both compounds significantly inhibited spontaneous synchronous Ca2+ oscillations (SCOs) and epileptic discharges induced by 4-aminopyridine, showing the potential for antiepileptic drug research. The 5,9-boronic ester derivative of 2 did not change its SCO inhibitory activity.

Psychrophilic Yeasts: Insights into Their Adaptability to Extremely Cold Environments.

Psychrophilic yeasts are distributed widely on Earth and have developed adaptation strategies to overcome the effect of low temperatures. They can adapt to low temperatures better than bacteriophyta. However, to date, their whole-genome sequences have been limited to the analysis of single strains of psychrophilic yeasts, which cannot be used to reveal their possible psychrophilic mechanisms to adapt to low temperatures accurately and comprehensively. This study aimed to compare different sources of psychrophilic yeasts at the genomic level and investigate their cold-adaptability mechanisms in a comprehensive manner. Nine genomes of known psychrophilic yeasts and three representative genomes of mesophilic yeasts were collected and annotated. Comparative genomic analysis was performed to compare the differences in their signaling pathways, metabolic regulations, evolution, and psychrophilic genes. The results showed that fatty acid desaturase coding genes are universal and diverse in psychophilic yeasts, and different numbers of these genes exist (delta 6, delta 9, delta 12, and delta 15) in the genomes of various psychrophilic yeasts. Therefore, they can synthesize polyunsaturated fatty acids (PUFAs) in a variety of ways and may be able to enhance the fluidity of cell membranes at low temperatures by synthesizing C18:3 or C18:4 PUFAs, thereby ensuring their ability to adapt to low-temperature environments. However, mesophilic yeasts have lost most of these genes. In this study, psychrophilic yeasts could adapt to low temperatures primarily by synthesizing PUFAs and diverse antifreeze proteins. A comparison of more psychrophilic yeasts' genomes will be useful for the study of their psychrophilic mechanisms, given the presence of additional potential psychrophilic-related genes in the genomes of psychrophilic yeasts. This study provides a reference for the study of the psychrophilic mechanisms of psychrophilic yeasts.

Vestibular evoked myogenic potential may predict the hearing recovery in patients with unilateral idiopathic sudden sensorineural hearing loss.

Objective: This study investigates the association between vestibular function and prognosis in patients with unilateral idiopathic sudden sensorineural hearing loss (UISSNHL). Design: A retrospective analysis of 64 patients with UISSNHL was performed. Pure tone audiometry and vestibular function tests for otoliths and semicircular canals were performed to assess the influence of vestibular functional status on the outcome of patients with UISSNHL. Results: Patients with abnormal cervical vestibular evoked myogenic potential (cVEMP) or ocular vestibular evoked myogenic potential (oVEMP) responded less favorably to treatment. In the ineffective group, cVEMP was normal in four patients (6.3%) and oVEMPs in three (4.7%). Meanwhile, cVEMP was abnormal in 32 patients (50.0%) and oVEMP in 33 (51.6%). Better hearing recovery occurred in those with normal cVEMP (33.76 ± 15.07 dB HL improvement) or oVEMP (32.55 ± 19.56 dB HL improvement), but this was not the case in those with normal caloric tests. Patients with abnormalities in both cVEMP and oVEMP were less responsive to treatment and had worse hearing recovery than those with normal results in only one of the two tests. Conclusion: Abnormal oVEMP and/or cVEMP results indicate poor auditory outcomes in patients with UISSNHL. Patients with impaired otolith organ function are likely to have a larger and more severe pathological change in their inner ear.

A Comparison of Local Endolymphatic Sac Decompression, Endolymphatic Mastoid Shunt, and Wide Endolymphatic Sac Decompression in the Treatment of Intractable Meniere's Disease: A Short-Term Follow-Up Investigation.

BACKGROUND: Meniere's disease (MD) is an inner ear disorder, characterized by recurrent attacks of vertigo, low-frequency sensorineural hearing loss, tinnitus, and aural fullness. Endolymphatic sac surgery is an effective treatment to control vertigo attacks but without causing a hearing loss for intractable MD. However, the methods and effects of endolymphatic sac surgery have been controversial for many years, and the relationship between the vertigo control rates of different endolymphatic sac surgery methods is not well-documented. OBJECTIVES: This study compared the vertigo control rate, hearing outcome, and quality of life (QOL) among different endolymphatic sac surgery, such as local endolymphatic sac decompression (LESD), endolymphatic sac mastoid shunt (ESMS), and wide endolymphatic sac decompression (WESD). MATERIALS AND METHODS: We retrospectively analyzed the patients who underwent endolymphatic sac surgery from January 2008 to June 2019. The control rate of vertigo and QOL scores were compared after 2 years of follow-up. The QOL was scored with validation of the MD patient-oriented symptom-severity index (MDPOSI). The pure tone thresholds of all patients at pre- and postoperation were also compared. RESULTS: In total, 83 MD patients with complete follow-up data were included in the study, i.e., 20 patients with LESD, 28 patients with ESMS, and 35 patients with WESD. Results showed a better vertigo control with WESD than the other groups (70% with LESD, 71.4% with ESMS, and 88.6% with WESD). The QOL was improved after surgery in all groups in which the difference was statistically significant (QOL, preoperative vs. postoperative, 38.2 vs. 10.1 with LESD, 37.8 vs. 9.6 with ESMS, and 37.6 vs. 8.3 with WESD), respectively. After endolymphatic sac surgery, the hearing was well-preserved in the three groups [pure tone averages (PTAs), dB, preoperative vs. postoperative, 41.0 ± 19.3 vs. 40.8 ± 17.9 with LESD, 39.7 ± 16.4 vs. 40.8 ± 18.2 with ESMS, and 38.5 ± 18.7 vs. 36.6 ± 19.5 with WESD]. CONCLUSION: Wide endolymphatic sac decompression has a higher vertigo control rate, better improvement of QOL, and relatively higher hearing stability or improvement rate after surgery in patients with MD compared with LESD and ESMS.

Comparison of Deep-Sea Picoeukaryotic Composition Estimated from the V4 and V9 Regions of 18S rRNA Gene with a Focus on the Hadal Zone of the Mariana Trench.

Diversity of microbial eukaryotes is estimated largely based on sequencing analysis of the hypervariable regions of 18S rRNA genes. But the use of different regions of 18S rRNA genes as molecular markers may generate bias in diversity estimation. Here, we compared the differences between the two most widely used markers, V4 and V9 regions of the 18S rRNA gene, in describing the diversity of epipelagic, bathypelagic, and hadal picoeukaryotes in the Challenger Deep of the Mariana Trench, which is a unique and little explored environment. Generally, the V9 region identified more OTUs in deeper waters than V4, while the V4 region provided greater Shannon diversity than V9. In the epipelagic zone, where Alveolata was the dominant group, picoeukaryotic community compositions identified by V4 and V9 markers are similar at different taxonomic levels. However, in the deep waters, the results of the two datasets show clear differences. These differences were mainly contributed by Retaria, Fungi, and Bicosoecida. The primer targeting the V9 region has an advantage in amplifying Bicosoecids in the bathypelagic and hadal zone of the Mariana Trench, and its high abundance in V9 dataset pointed out the possibility of Bicosoecids as a dominant group in this environment. Chrysophyceae, Fungi, MALV-I, and Retaria were identified as the dominant picoeukaryotes in the bathypelagic and hadal zone and potentially play important roles in deep-sea microbial food webs and biogeochemical cycling by their phagotrophic, saprotrophic, and parasitic life styles. Overall, the use of different markers of 18S rRNA gene allows a better assessment and understanding of the picoeukaryotic diversity in deep-sea environments.

Single-Cell RNA Sequencing Analysis Reveals Greater Epithelial Ridge Cells Degeneration During Postnatal Development of Cochlea in Rats.

Greater epithelial ridge cells, a transient neonatal cell group in the cochlear duct, which plays a crucial role in the functional maturation of hair cell, structural development of tectorial membrane, and refinement of audio localization before hearing. Greater epithelial ridge cells are methodologically homogeneous, while whether different cell subtypes are existence in this intriguing region and the degeneration mechanism during postnatal cochlear development are poorly understood. In the present study, single-cell RNA sequencing was performed on the cochlear duct of postnatal rats at day 1 (P1) and day 7 (P7) to identify subsets of greater epithelial ridge cell and progression. Gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis were used to examine genes enriched biological processes in these clusters. We identified a total of 26 clusters at P1 and P7 rats and found that the cell number of five cell clusters decreased significantly, while four clusters had similar gene expression patterns and biological properties. The genes of these four cell populations were mainly enriched in Ribosome and P13K-Akt signal pathway. Among them, Rps16, Rpsa, Col4a2, Col6a2, Ctsk, and Jun are particularly interesting as their expression might contribute to the greater epithelial ridge cells degeneration. In conclusion, our study provides an important reference resource of greater epithelial ridge cells landscape and mechanism insights for further understanding greater epithelial ridge cells degeneration during postnatal rat cochlear development.

Immunosuppressive 9,10-Secosteroids from the Gorgonian Verrucella umbraculum Collected in the South China Sea.

Four new 9,10-secosteroids, verrucellols A-D (1-4), together with 12 known derivatives (5-16) were isolated from the gorgonian Verrucella umbraculum collected in the South China Sea. The structures of the new compounds were established by spectroscopic analysis and comparison with reported data. These compounds exhibited significant suppressive effects on CD4+ T lymphocyte cell differentiation in an in vitro bioassay. This is the first report of 9,10-secosteroids exhibiting immunomodulation activity.

XIAP inhibits gentamicin-induced hair cell damage and ototoxicity through the caspase-3/9 pathway.

Gentamicin (GM), an aminoglycoside antibiotic, is one commonly used clinical drugs with ototoxic side effects. One of the most principal mechanisms of its ototoxicity is that GM can activate caspase-mediated cell death pathways in the cochlea. Since the anti-apoptotic protein known as X-linked Inhibitor of Apoptosis Protein (XIAP) has been reported to directly bind to activated caspase protein and inhibit their activities, we hypothesized that it might protect cochlea hair cells from GM ototoxicity. To evaluate this hypothesis, postnatal day 2-3 (P2-3) transgenic (TG) mice, in which XIAP gene is over-expressed under a pure C57BL/6J genetic background was constructed. We first extracted the cochlea tissue of normal mice and treated them with different concentrations of GM, and the number of hair cells were observed to determine the concentration of GM used in subsequent experiments. Next, we used Western Blot experiment to examine the effect of GM on XIAP protein expression in normal mouse cochlea, and then Western Blot and RT-PCR experiments were used to identify the transgenic mice. Finally, immunofluorescence assays were used to detect the effect of GM on the expression of caspase protein and verify the protective effect of XIAP. We found that GM at a concentration of 0.5 mM significantly affected the function of cochlea hair cells, up-regulating the expression of cleaved-caspase-3 and cleaved-caspase-9 protein but down-regulating XIAP protein. In the cochlea tissues of TG mice, this effect of GM was suppressed, and the destruction of hair cells was significantly reduced, and the cleaved-caspase-3 and cleaved-caspase-9 proteins were significantly suppressed. These results suggested that XIAP reduces GM-induced ototoxicity and caspase-3/9 pathway is associated with this process.

Identification, characterization and expression analyses of cholinesterases genes in Yesso scallop (Patinopecten yessoensis) reveal molecular function allocation in responses to ocean acidification.

Cholinesterases are key enzymes in central and peripheral cholinergic nerve system functioning on nerve impulse transmission in animals. Though cholinesterases have been identified in most vertebrates, the knowledge about the variable numbers and multiple functions of the genes is still quite meagre in invertebrates, especially in scallops. In this study, the complete cholinesterase (ChE) family members have been systematically characterized in Yesso scallop (Patinopecten yessoensis) via whole-genome scanning through in silico analysis. Ten ChE family members in the genome of Yesso scallop (designated PyChEs) were identified and potentially acted to be the largest number of ChE in the reported species to date. Phylogenetic and protein structural analyses were performed to determine the identities and evolutionary relationships of these genes. The expression profiles of PyChEs were determined in all developmental stages, in healthy adult tissues, and in mantles under low pH stress (pH 6.5 and 7.5). Spatiotemporal expression suggested the ubiquitous functional roles of PyChEs in all stages of development, as well as general and tissue-specific functions in scallop tissues. Regulation expressions revealed diverse up- and down-regulated expression patterns at most time points, suggesting different functional specialization of gene superfamily members in response to ocean acidification (OA). Evidences in gene number, phylogenetic relationships and expression patterns of PyChEs revealed that functional innovations and differentiations after gene duplication may result in altered functional constraints among PyChEs gene clusters. Collectively, our results provide the potential clues that the selection pressures coming from the environment were the potential inducement leading to function allocation of ChE family members in scallop.

Alternarin A, a Drimane Meroterpenoid, Suppresses Neuronal Excitability from the Coral-Associated Fungi Alternaria sp. ZH-15.

Alternarin A (1), a rearranged drimane meroterpenoid characterized by a thioglycerate moiety, was isolated together with two known analogues from the coral-associated fungi Alternaria sp. ZH-15. Its structure was determined based on spectroscopic analysis, modified Mosher's method, and TDDFT/ECD calculations. In a primary cultured cortical neuronal network, compound 1 effectively inhibited the activity of spontaneous synchronous Ca2+ oscillations and 4-aminopyridine induced epileptic discharges in the low micromolar concentration range.

Swinhoeisterols from the South China Sea Sponge Theonella swinhoei.

Swinhoeisterols C-F (1-4), four new steroids having a rearranged 6/6/5/7 ring system, were isolated from the Xisha sponge Theonella swinhoei, together with the known analogue swinhoeisterol A (5). Their structures were determined based on spectroscopic analysis, TDDFT-ECD and optical rotation calculations, and biogenetic correlations. In an in vitro assay, compound 1 showed an inhibitory effect on (h)p300 with an IC50 value of 8.8 µM, whereas compounds 2-4 were not active.

A novel PIK3CD C896T mutation detected in bilateral sudden sensorineural hearing loss using next generation sequencing: An indication of primary immunodeficiency.

OBJECTIVE: To investigate immune-related genetic background in bilateral sudden sensorineural hearing loss (SSNHL). CASE REPORT AND METHODS: The case is a 45-year-old man presenting with a 7-year history of bilateral profound SSNHL. Blood biochemical testing demonstrated increased levels of total cholesterol (5.88 mmol/L). Tests for hepatitis B showed a positive antibody against the hepatitis B core antigen. Complement C3 was below the normal value, and complement C4 and IgG were in the lower range of normal values. CT images showed a normal inner ear and vestibular aqueduct but round window membranous ossification on both sides. A total number of 232 immune-associated genes were sequenced using the next generation sequencing technique. RESULTS: Mutations were detected in 5 genes, including the phosphoinositide 3-kinase catalytic subunit delta (PIK3CD), caspase recruitment domain-containing protein 9 (CARD9), complement factor H-related (CFHR2), immunoglobulin lambda-like polypeptide 1 Protein (IGLL1), and transmembrane channel-like gene family 8 (TMC8). In the PIK3CD gene, a C896T substitute in exon 7 was detected. This mutation causes primary immunodeficiency and is an autosomal dominant disease. CONCLUSION: The PIK3CD C896T mutation responsible for primary immunodeficiency may contribute to the onset of bilateral SSNHL with subsequent rapid progression.

Primary observation of early transtympanic steroid injection in patients with delayed treatment of noise-induced hearing loss.

Approximately 5% of the population worldwide suffer from varieties of noise-induced hearing loss (NIHL). Prevention and early identification remain the best methods of approaching NIHL. Over the years, numerous methods of improving the outcome in patients presenting with NIHL have been evaluated; however, these are far from sufficient. The present trial aimed to evaluate the effectiveness of early transtympanic steroid injection in patients with delayed treatment of NIHL. Because systemic steroid treatment is the most common treatment of choice in the management of NIHL, it was considered unethical to replace the first-line systemic steroid treatment with transtympanic treatment. Therefore, the present study evaluated the combination of conventional steroid treatment with a transtympanic steroid injection. A total of 53 patients diagnosed with delayed treatment of NIHL were randomized into a transtympanic group (TR group, n=27) and a control group (n=26). The TR group received the conventional steroid treatment plus four courses of additional transtympanic injections of methylprednisolone 3 days after NIHL onset, and the control group received the conventional steroid treatment. Transtympanic injection was performed through laser-assisted myringotomy (a 0.5- to 1-mm perforation was made in the tympanic membrane) under an operation microscope. A total of 51.9% of the patients in the TR group had a ≥15-dB HL improvement in pure-tone average, compared with 23.1% of the patients in the control group, at the 8-week follow-up audiogram. A total of 66.7% of the patients in the TR group had an improvement of ≥15% in the speech discrimination score, compared with 30.8% of patients in the control group, 8 weeks after the treatment. The differences between the two groups were statistically significant. The outcome of this trial indicates that delayed treatment of NIHL may be preferable if transtympanic therapy can be applied earlier. The large variability in the individual results indicates that additional carefully controlled studies with larger sample sizes are needed to understand the effect of early transtympanic therapy in patients with delayed treatment of NIHL.

Cell-cell junctions: a target of acoustic overstimulation in the sensory epithelium of the cochlea.

BACKGROUND: Exposure to intense noise causes the excessive movement of the organ of Corti, stretching the organ and compromising sensory cell functions. We recently revealed changes in the transcriptional expression of multiple adhesion-related genes during the acute phases of cochlear damage, suggesting that the disruption of cell-cell junctions is an early event in the process of cochlear pathogenesis. However, the functional state of cell junctions in the sensory epithelium is not clear. Here, we employed graded dextran-FITC, a macromolecule tracer that is impermeable to the organ of Corti under physiological conditions, to evaluate the barrier function of cell junctions in normal and noise-traumatized cochlear sensory epithelia. RESULTS: Exposure to an impulse noise of 155 dB (peak sound pressure level) caused a site-specific disruption in the intercellular junctions within the sensory epithelium of the chinchilla cochlea. The most vulnerable sites were the junctions among the Hensen cells and between the Hensen and Deiters cells within the outer zone of the sensory epithelium. The junction clefts that formed in the reticular lamina were permeable to 40 and 500 but not 2,000 kDa dextran-FITC macromolecules. Moreover, this study showed that the interruption of junction integrity occurred in the reticular lamina and also in the basilar membrane, a site that had been considered to be resistant to acoustic injury. Finally, our study revealed a general spatial correlation between the site of sensory cell damage and the site of junction disruption. However, the two events lacked a strict one-to-one correlation, suggesting that the disruption of cell-cell junctions is a contributing, but not the sole, factor for initiating acute sensory cell death. CONCLUSIONS: Impulse noise causes the functional disruption of intercellular junctions in the sensory epithelium of the chinchilla cochlea. This disruption occurs at an early phase of cochlear damage. Understanding the role of this disruption in cochlear pathogenesis will require future study.

[Hair cells apoptosis and the activation of P53 protein in intensive impulse noise induced cochlear lesion].

OBJECTIVE: To explore the pattern of hair cell injury and expression of P53 apoptosis protein in intensive impulse noise injured cochlear hair cells in guinea pigs. METHODS: Twelve adult guinea pigs were exposed to a series of 40 pairs of impulse noise (2 second intervals) at the intensity of 168 dB (SPL). Animals were terminated at 3, 6 and 12 hours after noise exposure, respectively. Cochlear surface preparations were performed with a double staining of FITC-conjugated phalloidin and propidium iodide for the observations of the stereocilia and the nucleus. P53 immunochemical staining was also performed 12 hours post-noise exposure to observe if there was expression of p53 protein in injured hair cells. Results Three hours after noise exposure, the outer hair cells at the end of basal turn and beginning of second turn were destroyed first with a character of nuclear condensation. Six hours post-noise exposure, many hair cells in the center of damage region had nuclear fragmentations, and the damaging area expanded towards to basal turn and apical turn. Twelve hours after noise exposure, the nucleus in most outer hair cells and inner hair cells at the region of damage center were missing. The nuclear condensation and fragmentation were appeared in hair cells in both sides of the center region of degeneration. P53 immunoreactive products were also found in damaged hair cells, not only in the central damage area, but also in the basal turn and the third turn. CONCLUSIONS: Intensive impulse noise resulted in apoptosis of cochlear hair cells that initiated between the end of basal turn and the beginning of second turn. Hair cell degeneration spread to basal and third turn along the basilar membrane. P53 may play an important role in impulse noise induced-hair cell apoptosis.

Transport augmentation through the blood-inner ear barriers of guinea pigs treated with 3-nitropropionic acid and patients with acute hearing loss, visualized with 3.0 T MRI.

OBJECTIVE: To visualize the permeability changes in the blood-inner ear barriers of guinea pigs with acute mitochondria dysfunction and in patients with acute hearing loss using contrast agent-enhanced MRI. MATERIALS AND METHODS: An animal model of acute mitochondria dysfunction-induced hearing loss was created by introducing 3-nitropropionic acid (3-NP) intratympanically in guinea pigs. Vestibular disorder and hearing loss were evaluated. An MRI was performed at 2 h after either intravenous (IV) or intratympanic administration of dimeglumine gadopentetate (Gd-DTPA), using 3D fast-recovery fast spin-echo (FRFSE) and 3D fluid-attenuated inversion recovery (FLAIR) sequences. The inner ears of patients with acute hearing loss were imaged using a 3D-FLAIR sequence with a 3 T MRI machine at 2 h post-IV injection with Gd-DTPA at a routine dosage. RESULTS: Guinea pigs treated with 3-NP showed severe hearing loss and vestibular dysfunction. MR imaging with a 3D-FLAIR sequence at 2 h post-IV injection of Gd-DTPA was an optimal method for visualizing transport augmentation through the blood-inner ear barriers. Apoptosis appeared in the stria vascularis and Reissner's membrane of cochleae treated with 3NP. Similar MRI changes were observed in patients with SSHL and Ménière's disease 2 h post-IV injection with Gd-DTPA using the 3D-FLAIR sequence. CONCLUSION: Variations of Gd-DTPA transport through the blood-inner ear barriers induced by mitochondria toxin was visualized in guinea pigs using a clinical 3.0 T machine. IV injection of Gd-DTPA with 2 h of waiting time and imaging with 3D-FLAIR are optimal methods. The MRI observation of the inner ear in the animal model was translatable to patients with acute hearing loss, using an IV injection of Gd-DTPA at the routine dosage.

The effects of acoustic environment after traumatic noise exposure on hearing and outer hair cells.

Previous studies reported that exposure to non-traumatic level sounds after traumatic noise exposure reduced the degree of noise-induced hearing loss and hair cell stereocilia damage. The current study investigated the effects of a 3-day post-noise acoustic environment on the degree of noise-induced hearing loss and cochlear damage. Female chinchillas were exposed to traumatic continuous noise (4 kHz octave-band noise) at 107 dB SPL for 1h and then placed in either an augmented acoustic environment (AAE) or deprived acoustic environment (DAE) for 3 days. The AAE group was exposed to a broad-band noise (4-20 kHz) at 80 dB SPL and the DAE animals were fit with conventional earplugs to minimize the level of acoustic stimulation. Auditory brainstem responses (ABRs) were recorded before and 3 days after the traumatic noise exposure. The AAE group showed a significantly lower average threshold shift at the frequencies of 4 and 8 kHz (p<0.01). Correspondingly, significantly fewer missing and dying outer hair cells (OHCs) were observed in the AAE group than in the DAE group. Although the cochlear reduced and oxidized glutathione levels (GSH and GSSG, respectively) were essentially the same in two groups at day 3, significant correlations were found between GSSG levels and mean ABR threshold shift (1-16 kHz) in the AAE group; as well as GSSG and percentage of total OHC loss in the DAE group. The results suggest that post-noise acoustic environment influenced the degree of hearing loss and OHC deterioration after traumatic noise exposure.

Isolation, growth and differentiation of hair cell progenitors from the newborn rat cochlear greater epithelial ridge.

Mammalian cochlear hair cell loss is irreversible and leads to permanent hearing loss. To restore hearing physiologically, it is necessary to generate new functional hair cells either from endogenous cells or from exogenously transplanted hair cells/progenitors. Previous studies suggest that cochlear greater epithelial ridge (GER) and lesser epithelial ridge (LER) cells are capable of differentiating into hair cells. While it was recently possible to obtain and culture pure LER progenitors, isolation of pure GER progenitors has not been reported. Here we describe a method that allows isolation of pure GER cells from neonatal rat cochleae. The cochlear epithelial sheet (CES) containing GER progenitor cells was mechanically separated from the underlying mesenchymal tissue after digestion with thermolysin. The GER area could then be dissected following mechanical removal of organ of Corti as well as all the lateral area. The isolated GER cells showed significant proliferation and expressed markers for GER cells but not markers for hair cells or LER. When the GER cells were cultured in serum-free medium containing epidermal growth factor, spheres were formed where they continued to proliferate. Furthermore, when GER cells were induced to express Hath1 or co-cultured with mesenchymal cells prepared from neonate rat cochleae, they showed the potential to differentiate into hair cell-like cells. Successful isolation, culture and differentiation of GER hair cell progenitors will shed additional light on the mechanism of hair cell differentiation and potential hair cell replacement.