Functional evaluation of novel variants of B4GALNT1 in a patient with hereditary spastic paraplegia and the general population.

Hereditary spastic paraplegia (HSP) is a heterogeneous group of neurological disorders that are characterized by progressive spasticity and weakness in the lower limbs. SPG26 is a complicated form of HSP, which includes not only weakness in the lower limbs, but also cognitive impairment, developmental delay, cerebellar ataxia, dysarthria, and peripheral neuropathy, and is caused by biallelic mutations in the B4GALNT1 (beta-1,4-N-acetylgalactosaminyltransferase 1) gene. The B4GALNT1 gene encodes ganglioside GM2/GD2 synthase (GM2S), which catalyzes the transfer of N-acetylgalactosamine to lactosylceramide, GM3, and GD3 to generate GA2, GM2, and GD2, respectively. The present study attempted to characterize a novel B4GALNT1 variant (NM_001478.5:c.937G>A p.Asp313Asn) detected in a patient with progressive multi-system neurodegeneration as well as deleterious variants found in the general population in Japan. Peripheral blood T cells from our patient lacked the ability for activation-induced ganglioside expression assessed by cell surface cholera toxin binding. Structural predictions suggested that the amino acid substitution, p.Asp313Asn, impaired binding to the donor substrate UDP-GalNAc. An in vitro enzyme assay demonstrated that the variant protein did not exhibit GM2S activity, leading to the diagnosis of HSP26. This is the first case diagnosed with SPG26 in Japan. We then extracted 10 novel missense variants of B4GALNT1 from the whole-genome reference panel jMorp (8.3KJPN) of the Tohoku medical megabank organization, which were predicted to be deleterious by Polyphen-2 and SIFT programs. We performed a functional evaluation of these variants and demonstrated that many showed perturbed subcellular localization. Five of these variants exhibited no or significantly decreased GM2S activity with less than 10% activity of the wild-type protein, indicating that they are carrier variants for HSP26. These results provide the basis for molecular analyses of B4GALNT1 variants present in the Japanese population and will help improve the molecular diagnosis of patients suspected of having HSP.

Feasibility of Multimodal Artificial Intelligence Using GPT-4 Vision for the Classification of Middle Ear Disease: Qualitative Study and Validation.

BACKGROUND: The integration of artificial intelligence (AI), particularly deep learning models, has transformed the landscape of medical technology, especially in the field of diagnosis using imaging and physiological data. In otolaryngology, AI has shown promise in image classification for middle ear diseases. However, existing models often lack patient-specific data and clinical context, limiting their universal applicability. The emergence of GPT-4 Vision (GPT-4V) has enabled a multimodal diagnostic approach, integrating language processing with image analysis. OBJECTIVE: In this study, we investigated the effectiveness of GPT-4V in diagnosing middle ear diseases by integrating patient-specific data with otoscopic images of the tympanic membrane. METHODS: The design of this study was divided into two phases: (1) establishing a model with appropriate prompts and (2) validating the ability of the optimal prompt model to classify images. In total, 305 otoscopic images of 4 middle ear diseases (acute otitis media, middle ear cholesteatoma, chronic otitis media, and otitis media with effusion) were obtained from patients who visited Shinshu University or Jichi Medical University between April 2010 and December 2023. The optimized GPT-4V settings were established using prompts and patients' data, and the model created with the optimal prompt was used to verify the diagnostic accuracy of GPT-4V on 190 images. To compare the diagnostic accuracy of GPT-4V with that of physicians, 30 clinicians completed a web-based questionnaire consisting of 190 images. RESULTS: The multimodal AI approach achieved an accuracy of 82.1%, which is superior to that of certified pediatricians at 70.6%, but trailing behind that of otolaryngologists at more than 95%. The model's disease-specific accuracy rates were 89.2% for acute otitis media, 76.5% for chronic otitis media, 79.3% for middle ear cholesteatoma, and 85.7% for otitis media with effusion, which highlights the need for disease-specific optimization. Comparisons with physicians revealed promising results, suggesting the potential of GPT-4V to augment clinical decision-making. CONCLUSIONS: Despite its advantages, challenges such as data privacy and ethical considerations must be addressed. Overall, this study underscores the potential of multimodal AI for enhancing diagnostic accuracy and improving patient care in otolaryngology. Further research is warranted to optimize and validate this approach in diverse clinical settings.

Temporal Swelling Following Cochlear Implantation: Frequency, Treatment, and Outcomes.

OBJECTIVE: To investigate the frequency, treatment, and outcomes of postoperative delayed-onset swelling around cochlear implants. STUDY DESIGN: Retrospective, observational, nonrandomized group study. SETTING: Academic medical center. PATIENTS/INTERVENTIONS: Among 354 patients (516 ears) who underwent cochlear implantation (CI) at our hospital between May 2009 and October 2022, 329 (472 ears: 138 children [246 ears] and 191 adults [226 ears]) with a follow-up period of >3 months were included. MAIN OUTCOME MEASURES: Physical examination and computed tomography of the head were performed. RESULTS: In total, 5.5% (26/472 ears) had a history of delayed-onset swelling around the implant. This complication occurred in 9.8% (24/246 ears) of children and 0.9% (2/226 ears) of adults. The mean time to onset of swelling was 50 (range, 5.5-147) months following CI. In 60% (21/35) of the cases, the cause was unknown, whereas in 25.7% (9/35) and 11.5% (4/35) of cases, it was head trauma and acute inflammation, respectively. Conservative treatment (observation, antibiotics, and/or strong magnetic compression) was adapted in 91.4% (32/35) of cases. After conservative treatment, revision CI surgery was performed in one ear. Additionally, recurrent swelling was observed in 23.1% (6/26 ears) of swelling cases. CONCLUSIONS: The results suggest that delayed-onset swelling around implants occurs more frequently in children than in adults because of the higher incidence rates of head trauma and acute otitis media in children. In most cases, conservative treatment was adequate; however, careful follow-up is necessary. Our findings can serve as a reference for optimizing care and intervention options after CI.

Treatment following Triple-AAV Delivery in Mature Murine Model of Human CDH23-Associated Hearing Loss.

This study aimed to investigate the transduction efficiency of triple adeno-associated virus (AAV) vectors in the cochleae of adult mice, focusing on large-gene-associated hearing loss (HL). Additionally, we sought to evaluate the feasibility of cochlear gene therapy in a mouse model of human CDH23-mediated HL using the triple AAV approach. To create a reporter protein, we fused EGFP to mCherry, which was then divided into three parts, each packaged in a separate AAV2/2 vector. Four weeks after co-injecting the triple AAV vectors into 4-5-week-old mice, we assessed transduction efficiency. We found that up to 5.9% of inner hair cells were positive for both EGFP and mCherry. Subsequently, we developed triple Cdh23 AAV vectors for therapeutic purposes. After administering these vectors to 4- to 5-week-old C57/BL6 mice, we conducted auditory tests and immunohistochemistry studies over a period of 60 weeks. Co-injecting triple Cdh23-AAVs did not alter auditory function or lead to hair cell degeneration. In conclusion, this study confirms the feasibility of the triple-AAV approach for cochlear gene delivery. While this strategy did not produce any treatment effects, our findings suggest that large deafness genes could be potential future targets for cochlear gene therapy.

Enhanced Cochlear Transduction by AAV9 with High-Concentration Sucrose.

The inner ear is a primary lesion in sensorineural hearing loss and has been a target in gene therapy. The efficacy of gene therapy depends on achieving sufficient levels of transduction at a safe vector dose. Vectors derived from various adeno-associated viruses (AAVs) are predominantly used to deliver therapeutic genes to inner ear cells. AAV9 and its variants vector are attractive candidates for clinical applications since they can cross the mesothelial cell layer and transduce inner hair cells (IHCs), although this requires relatively high doses. In this study, we investigated the effects of sucrose on the transduction of a variant of the AAV9 vector for gene transfer in the inner ear. We found that high concentrations of sucrose increased gene transduction in House Ear Institute-Organ of Corti 1 (HEI-OC1) cells in vitro. In addition, we demonstrated that simultaneous administration of sucrose enhanced the transduction of mouse IHCs and spiral ligament cells using an AAV9 variant vector. The procedure did not increase the thresholds in the auditory brainstem response, suggesting that sucrose had no adverse effect on auditory function. This versatile method may be valuable in the development of novel gene therapies for adult-onset sensorineural hearing loss.

The relationship between preoperative factors and the pattern of longitudinal improvement in speech perception following cochlear implantation.

BACKGROUND: Many studies have discussed the factors influencing hearing outcomes after cochlear implantation, but few have addressed improvements in speech perception for these patients over time. OBJECTIVE: To investigate the relationship between preoperative factors and the pattern of longitudinal improvement in speech perception following cochlear implantation (CI). MATERIALS AND METHODS: This study enrolled 83 patients (96 ears) who underwent CI at Shinshu University Hospital. The patients were assessed up to 12 months after CI by a monosyllable test, and showed either delayed improvement (DI), early improvement (EI), or stable improvement (SI) when compared with their preoperative score. Eight preoperative variables were also examined for their effects on speech perception over time. RESULTS: The DI, EI, SI groups comprised 35.4%, 43.8%, and 20.8% of all patients, respectively. Patients in the DI group were older at surgery than those in the EI and SI groups, and their onset age were also older than that in the SI group. No other preoperative variables showed significant differences across the three groups. CONCLUSIONS AND SIGNIFICANCE: Our findings revealed that age at implantation and age at onset of hearing loss significantly affected the improvement pattern of speech perception. Age may be useful in predicting recovery of speech perception after CI.

Detailed clinical features and genotype-phenotype correlation in an OTOF-related hearing loss cohort in Japan.

Mutations in the OTOF gene are a common cause of hereditary hearing loss and the main cause of auditory neuropathy spectrum disorder (ANSD). Although it is reported that most of the patients with OTOF mutations have stable, congenital or prelingual onset severe-to-profound hearing loss, some patients show atypical clinical phenotypes, and the genotype-phenotype correlation in patients with OTOF mutations is not yet fully understood. In this study, we aimed to reveal detailed clinical characteristics of OTOF-related hearing loss patients and the genotype-phenotype correlation. Detailed clinical information was available for 64 patients in our database who were diagnosed with OTOF-related hearing loss. As reported previously, most of the patients (90.6%) showed a "typical" phenotype; prelingual and severe-to-profound hearing loss. Forty-seven patients (73.4%) underwent cochlear implantation surgery and showed successful outcomes; approximately 85-90% of the patients showed a hearing level of 20-39 dB with cochlear implant and a Categories of Auditory Performance (CAP) scale level 6 or better. Although truncating mutations and p.Arg1939Gln were clearly related to severe phenotype, almost half of the patients with one or more non-truncating mutations showed mild-to-moderate hearing loss. Notably, patients with p.His513Arg, p.Ile1573Thr and p.Glu1910Lys showed "true" auditory neuropathy-like clinical characteristics. In this study, we have clarified genotype-phenotype correlation and efficacy of cochlear implantation for OTOF-related hearing loss patients in the biggest cohort studied to date. We believe that the clinical characteristics and genotype-phenotype correlation found in this study will support preoperative counseling and appropriate intervention for OTOF-related hearing loss patients.

Milestones toward cochlear gene therapy for patients with hereditary hearing loss.

A number of genes are reportedly responsible for hereditary hearing loss, which accounts for over 50% of all congenital hearing loss cases. Recent advances in genetic testing have enabled the identification of pathogenic variants in many cases, and systems have been developed to provide personalized treatment based on etiology. Gene therapy is expected to become an unprecedented curative treatment. Several reports have demonstrated the successful use of cochlear gene therapy to restore auditory function in mouse models of genetic deafness; however, many hurdles remain to its clinical application in humans. Herein, we focus on the frequency of deafness genes in patients with congenital and late-onset progressive hearing loss and discuss the following points regarding which genes need to be targeted to efficiently proceed with clinical application: (a) which cells' genes are expressed within the cochlea, (b) whether gene transfer to the targeted cells is possible using vectors such as adeno-associated virus, (c) what phenotype of hearing loss in patients is exhibited, and (d) whether mouse models exist to verify the effectiveness of treatment. Moreover, at the start of clinical application, gene therapy in combination with cochlear implantation may be useful for cases of progressive hearing loss.

Electric-acoustic stimulation with longer electrodes for potential deterioration in low-frequency hearing.

Background: Electric-acoustic stimulation (EAS) has emerged as a standard treatment for patients with high-frequency hearing loss. EAS is usually performed with shorter electrodes of 16-24 mm in length. As most EAS recipients gradually lose residual acoustic hearing in the implanted ear over time, EAS with longer electrodes without causing significant intra-cochlear damage might be ideal.Objective: The aim of this study was to investigate hearing preservation (HP) results after EAS surgery with longer electrodes.Methods: Ten patients (11 ears) with partial deafness that met the indications for EAS with a MED-EL FLEX28 electrode were included in this study. Auditory thresholds before and at 6 months after activation were examined.Results: In 100% of cases, HP was comfortably achieved, indicating that all patients could utilize acoustic amplification combined with electric stimulation.Conclusion: EAS with longer electrodes can offer broader cochlear coverage, resulting in natural frequency matching in comparison with shorter electrodes, even in EAS cases. The combination of advanced surgical techniques and flexible, long, straight electrodes permits deep insertion that reaches the apical region with little or no insertion trauma.

Hair Cell Transduction Efficiency of Single- and Dual-AAV Serotypes in Adult Murine Cochleae.

Gene delivery is a key component for the treatment of genetic hearing loss. To date, a myriad of adeno-associated virus (AAV) serotypes and surgical approaches have been employed to deliver transgenes to cochlear hair cells, but the efficacy of dual transduction remains unclear. Herein, we investigated cellular tropism of single injections of AAV serotype 1 (AAV1), AAV2, AAV8, AAV9, and Anc80L65, and quantitated dual-vector co-transduction rates following co-injection of AAV2 and AAV9 vectors in adult murine cochlea. We used the combined round window membrane and canal fenestration (RWM+CF) injection technique for vector delivery. Single AAV2 injections were most robust and transduced 96.7% ± 1.1% of inner hair cells (IHCs) and 83.9% ± 2.0% of outer hair cells (OHCs) throughout the cochlea without causing hearing impairment or hair cell loss. Dual AAV2 injection co-transduced 96.9% ± 1.7% of IHCs and 65.6% ± 8.95% of OHCs. Together, RWM+CF-injected single or dual AAV2 provides the highest auditory hair cell transduction efficiency of the AAV serotypes we studied. These findings broaden the application of cochlear gene therapy targeting hair cells.

Genetic testing has the potential to impact hearing preservation following cochlear implantation.

Background: Recent advances in less-invasive surgery and electrode design allow for a high degree of hearing preservation (HP) after cochlear implantation (CI), although residual hearing still deteriorates in some patients. To date, the factors predictive of preserving residual hearing remain a controversial topic.Objective: The aim of this study was to investigate the predictive factors, including the etiology of hearing loss (HL) as a patient-related factor, influencing residual HP after CI.Methods: Forty-four patients (50 ears, 41 families) with residual acoustic hearing who underwent CI were included. Auditory thresholds before and at 6 months after initial activation were measured. Genetic testing was performed to identify the responsible genes for HL.Results: We identified the cause of HL in 21 families (51.2%). HP was marginally correlated with age at implantation, while it was independent of pre-operative low-frequency hearing thresholds, cochlear duct length, and electrode length. We found that patients who had pathogenic variants in the CDH23, MYO7A, or MYO15A gene showed statistically better HP scores compared with patients with HL due to other causes (p = .002).Conclusions: Identification of the etiology of HL using genetic testing is likely to facilitate the prediction of HP after implant surgery.

Targeted Allele Suppression Prevents Progressive Hearing Loss in the Mature Murine Model of Human TMC1 Deafness.

Hearing loss is the most common human sensory deficit. Its correction has been the goal of several gene-therapy based studies exploring a variety of interventions. Although these studies report varying degrees of success, all treatments have targeted developing inner ears in neonatal mice, a time point in the structural maturation of the cochlea prior to 26 weeks gestational age in humans. It is unclear whether cochlear gene therapy can salvage hearing in the mature organ of Corti. Herein, we report the first study to test gene therapy in an adult murine model of human deafness. Using a single intracochlear injection of an artificial microRNA carried in an AAV vector, we show that RNAi-mediated gene silencing can slow progression of hearing loss, improve inner hair cell survival, and prevent stereocilia bundle degeneration in the mature Beethoven mouse, a model of human TMC1 deafness. The ability to study gene therapy in mature murine ears constitutes a significant step toward its translation to human subjects.

Enhanced viral-mediated cochlear gene delivery in adult mice by combining canal fenestration with round window membrane inoculation.

Cochlear gene therapy holds promise for the treatment of genetic deafness. Assessing its impact in adult murine models of hearing loss, however, has been hampered by technical challenges that have made it difficult to establish a robust method to deliver transgenes to the mature murine inner ear. Here in we demonstrate the feasibility of a combined round window membrane injection and semi-circular canal fenestration technique in the adult cochlea. Injection of both AAV2/9 and AAV2/Anc80L65 via this approach in P15-16 and P56-60 mice permits robust eGFP transduction of virtually all inner hair cells throughout the cochlea with variable transduction of vestibular hair cells. Auditory thresholds are not compromised. Transduction rate and cell tropism is primarily influenced by viral titer and AAV serotype but not age at injection. This approach is safe, versatile and efficient. Its use will facilitate studies using cochlear gene therapy in murine models of hearing loss over a wide range of time points.

Intravenous rAAV2/9 injection for murine cochlear gene delivery.

Gene therapy for genetic deafness is a promising approach by which to prevent hearing loss or to restore hearing after loss has occurred. Although a variety of direct approaches to introduce viral particles into the inner ear have been described, presumed physiological barriers have heretofore precluded investigation of systemic gene delivery to the cochlea. In this study, we sought to characterize systemic delivery of a rAAV2/9 vector as a non-invasive means of cochlear transduction. In wild-type neonatal mice (postnatal day 0-1), we show that intravenous injection of rAAV2/9 carrying an eGFP-reporter gene results in binaural transduction of inner hair cells, spiral ganglion neurons and vestibular hair cells. Transduction efficiency increases in a dose-dependent manner. Inner hair cells are transduced in an apex-to-base gradient, with transduction reaching 96% in the apical turn. Hearing acuity in treated animals is unaltered at postnatal day 30. Transduction is influenced by viral serotype and age at injection, with less efficient cochlear transduction observed with systemic delivery of rAAV2/1 and in juvenile mice with rAAV2/9. Collectively, these data validate intravenous delivery of rAAV2/9 as a novel and atraumatic technique for inner ear transgene delivery in early postnatal mice.

A clinical experience of 'STAMP' plate-guided Bonebridge implantation.

CONCLUSION: The surface template-assisted marker positioning (STAMP) method is useful for successful Bonebridge™ (BB) implantation on a planned site while avoiding dangerous positions. OBJECTIVES: To confirm the usefulness of the STAMP method for the safe operation of BB. METHODS: From a patient's temporal bone CT data, a guide plate and confirmation plate were generated by the STAMP method. The guide plate is used to mark the correct place for implantation, while the confirmation plate lets us know the correct angle and depth of the hole. RESULTS: With the guide plate, the correct place for BB implantation was easily found. The hole was made to be an appropriate size with the confirmation plate while exposing only a small part of sigmoid sinus as simulated. Finally, the BB implant was successfully placed exactly at the planned site.

Ubiquinol-10 supplementation activates mitochondria functions to decelerate senescence in senescence-accelerated mice.

AIM: The present study was conducted to define the relationship between the anti-aging effect of ubiquinol-10 supplementation and mitochondrial activation in senescence-accelerated mouse prone 1 (SAMP1) mice. RESULTS: Here, we report that dietary supplementation with ubiquinol-10 prevents age-related decreases in the expression of sirtuin gene family members, which results in the activation of peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), a major factor that controls mitochondrial biogenesis and respiration, as well as superoxide dismutase 2 (SOD2) and isocitrate dehydrogenase 2 (IDH2), which are major mitochondrial antioxidant enzymes. Ubiquinol-10 supplementation can also increase mitochondrial complex I activity and decrease levels of oxidative stress markers, including protein carbonyls, apurinic/apyrimidinic sites, malondialdehydes, and increase the reduced glutathione/oxidized glutathione ratio. Furthermore, ubiquinol-10 may activate Sirt1 and PGC-1α by increasing cyclic adenosine monophosphate (cAMP) levels that, in turn, activate cAMP response element-binding protein (CREB) and AMP-activated protein kinase (AMPK). INNOVATION AND CONCLUSION: These results show that ubiquinol-10 may enhance mitochondrial activity by increasing levels of SIRT1, PGC-1α, and SIRT3 that slow the rate of age-related hearing loss and protect against the progression of aging and symptoms of age-related diseases.

An Usher syndrome type 1 patient diagnosed before the appearance of visual symptoms by MYO7A mutation analysis.

Usher syndrome type 1 (USH1) appears to have only profound non-syndromic hearing loss in childhood and retinitis pigmentosa develops in later years. This study examined the frequency of USH1 before the appearance of visual symptoms in Japanese deaf children by MYO7A mutation analysis. We report the case of 6-year-old male with profound hearing loss, who did not have visual symptoms. The frequency of MYO7A mutations in profound hearing loss children is also discussed. We sequenced all exons of the MYO7A gene in 80 Japanese children with severe to profound non-syndromic HL not due to mutations of the GJB2 gene (ages 0-14 years). A total of nine DNA variants were found and six of them were presumed to be non-pathogenic variants. In addition, three variants of them were found in two patients (2.5%) with deafness and were classified as possible pathogenic variants. Among them, at least one nonsense mutation and one missense mutation from the patient were confirmed to be responsible for deafness. After MYO7A mutation analysis, the patient was diagnosed with RP, and therefore, also diagnosed with USH1. This is the first case report to show the advantage of MYO7A mutation analysis to diagnose USH1 before the appearance of visual symptoms. We believed that MYO7A mutation analysis is valid for the early diagnosis of USH1.

The first report of bilateral retropharyngeal lymph node metastasis from papillary thyroid carcinoma and review of the literature.

The sites of lymph node metastasis of papillary thyroid carcinomas are typically the paratracheal and jugular lymph nodes. On the other hand, metastasis to the retropharyngeal or parapharyngeal nodes from papillary thyroid carcinomas is very rare. During the last two decades, limited to cases with a histologically definite diagnosis by surgery, only 39 cases have been reported. All reported cases were unilateral retropharyngeal or parapharyngeal node metastasis except one metachronous bilateral case, and there were no reports of simultaneous bilateral cases within our literature review. We report three cases of retropharyngeal node metastasis from thyroid papillary carcinoma, including a case of bilateral nodal metastasis. Retropharyngeal node metastasis was successfully resected in all three patients by the transcervical approach. As pointed out in past reports, this report also suggests that prior neck dissection and/or metastasis to cervical lymph nodes might alter the direction of lymphatic drainage to the retrograde fashion, resulting in the unusual metastasis to the retropharyngeal lymph nodes, and there is a possibility of a bilateral pattern. Also, it is necessary to consider the possibility of metastasis from a papillary thyroid carcinoma in the differential diagnosis of lymph node swelling in the parapharyngeal space.