Prevalence of Noise-Induced Hearing Loss Related to the Mills in the Markets of the Municipality of Parakou in 2021

Introduction: Noise is the second leading cause of hearing loss in adults after presbycusis. The objective of this work was to study hearing loss induced by the noise of mills in the markets of Parakou. Methods: This was a descriptive and analytical cross-sectional study, conducted from February 3 to June 3, 2021 in the markets of Parakou. It concerned millers and sellers located within a 5 meter radius around the mills and among whom pure-tone audiometry was performed to detect a hearing loss. Subjects with no particular medical health history, under 55 years of age and having been working in these markets since more than 12 months, were included. Results: In this study, 103 subjects were selected, including 43 millers and 61 sellers. Their average age was 29 ± 13 years. The sex ratio was 0.49. The average length of service in the profession was 8 years with the extremes of 3 months and 47 years. They were exposed to noise on average 10 hours per day and 6 days a week. The average duration of weekly noise exposure was 23 h 28 min ± 13 h 32 min with the extremes of 5 h 00 min and 52 h 30 min. The average level of noise exposure was 90 dB with the extremes of 72 and 110 dB. 24 subjects reported symptoms related to noise such as headache, tinnitus, and hearing loss, with respective proportions of 22.33%, 20.39% and 06.80%. The prevalence of noise-related hearing loss was 26.21% (n = 27/103). Subjects with a notch at 4000 Hz and normal Average Hearing Loss (AHL) (20.39%) had a seven-time greater risk of developing noise-induced hearing loss (OR = 6.58;95% CI [2.54 - 18.8], p Conclusion: Hearing loss related to the noise of mills affected both millers and sellers near the mills in markets, hence the importance of regulating mills.

Evaluation of Digits-in-Noise Test and Hearing Handicap Inventory for Adults Screening in Patients with Occupational Noise-Induced Hearing Loss

Objective:To explore the clinical evaluation role of the Digits-in-Noise(DIN)test and Hearing Handicap Inventory for Adults Screening(HHIA-S)for patients with occupational noise-induced hearing loss and to observe and analyze their application values.Methods:Fifty patients with suspected occupational noise-induced hearing loss were randomly selected from the Department of Otolaryngology at the hospital as the research target.The collection period for the research cases spanned from January 2022 to November 2023,and all patients had a history of noise exposure.The DIN test and HHIA-S were used for hearing examinations,with clinical,comprehensive diagnosis serving as the gold standard to study their diagnostic performance.Results:The compliance rate of the DIN test was 88.00%,the HHIA-S’s compliance rate was 80.00%,and the combined compliance rate was 94.00%.The compliance rate of the DIN test and the combined compliance rates of the patients were statistically significant compared to the clinical gold standard data(P<0.05),while there was no difference between the compliance rate of the HHIA-S and the gold standard(P>0.05).The data shows that the sensitivity of the combined diagnosis is significantly higher than the sensitivity data of the DIN test and HHIA-S examination alone(P<0.05).Its specificity is 100.00%,and the accuracy data of the joint diagnosis in the degree were higher than those of the DIN test alone(P>0.05)and the HHIA-S alone(P<0.05).Conclusion:For patients with occupational noise-induced hearing loss,the joint evaluation of the DIN test and HHIA-S can significantly improve their diagnostic value with high sensitivity and accuracy.

Early detection of noise-induced hearing loss

BACKGROUND Noise-induced hearing loss(NIHL)is the second most common acquired hearing loss following presbycusis.Exposure to recreational noise and minimal use of hearing protection increase the prevalence of NIHL in young females.NIHL is irreversible.Identifying minor hearing pathologies before they progress to hearing problems that affect daily life is crucial.AIM To compare the advantages and disadvantages of extended high frequency(EHF)and otoacoustic emission and determine an indicator of hearing pathologies at the early sub-clinical stage.METHODS This cross-sectional study was implemented in West China Hospital of Sichuan University from May to September 2019.A total of 86 participants,aged 18-22 years,were recruited to establish normative thresholds for EHF.Another 159 adults,aged 18-25 years with normal hearing(0.25-8 kHz≤25 dBHL),were allocated to low noise and noise exposure groups.Distortion otoacoustic emission(DPOAE),transient evoked otoacoustic emissions(TEOAE),and EHF were assessed in the two groups to determine the superior technique for detecting early-stage noise-induced pathologies.The chi-square test was used to assess the noise and low noise exposure groups with respect to extended high-frequency audiometry(EHFA),DPOAE,and TEOAE.P≤0.05 was considered statistically significant.RESULTS A total of 86 participants(66 females and 20 males)aged between 18 and 22(average:20.58±1.13)years were recruited to establish normative thresholds for EHF.The normative thresholds for 9,10,11.2,12.5,14,16,18,and 20 kHz were 15,10,20,15,15,20,28,and 0 dBHL,respectively.A total of 201 participants were recruited and examined for eligibility.Among them,159 adults aged between 18 and 25 years were eligible in this study.No statistical difference was detected between the noise exposure and the low noise exposure groups using EHFA,DPOAE,and TEOAE(P>0.05)except in the right ear at 4 kHz using TEOAE(abnormal rate 20.4%vs 5.2%,respectively;P=0.05).CONCLUSION These results showed TEOAE as the earliest indicator of minor pathology compared to DPOAE and EHFA.However,a multicenter controlled study or prospective study is essential to verify these results.

Involvement of NLRP3-inflammasome pathway in noise-induced hearing loss

The inflammasome is a multiprotein oligomer in the cell cytoplasm and is part of the innate immune system.It plays a crucial role in the pathological process of noise-induced hearing loss(NIHL).However,the mechanisms of NLR family pyrin domain containing 3(NLRP3)inflammasome activation in NIHL have not been clearly demonstrated.In this study,miniature pigs were exposed to white noise at 120 dB(A)and auditory brainstem response measurements were used to measure their hearing function.Immunofluorescence staining,confocal laser scanning microscopy,western blot assay,and quantitative reverse transcription-polymerase chain reaction were used to analyze inflammasome-related protein distribution and expression.NLRP3,interleukin-1β,interleukin-18,and cleaved-caspase-1 were highly expressed in the cochlea after 120 dB(A)white noise exposure.Our findings suggest that NLRP3-inflammasomes in the cochlea may be activated after acoustic trauma,which may be an important mechanism of noise-induced hearing loss.

NRN1 and CAT Gene Polymorphisms, Complex Noise, and Lifestyles interactively Affect the Risk of Noise-induced Hearing Loss

Objective The effects of interactions between genetic and environmental factors on the noise-induced hearing loss(NIHL)are still unclear.This study aimed to assess interactions among gene polymorphisms,noise metrics,and lifestyles on the risk of NIHL.Methods A case-control study was conducted using 307 patients with NIHL and 307 matched healthy individuals from five manufacturing industries.General demographic data,lifestyle details,and noise exposure levels were recorded.The Kompetitive allele-specific polymerase chain reaction(KASP)was used to analyze the genotypes of 18 SNPs.Results GMDR model demonstrated a relevant interaction between NRN1 rs3805789 and CAT rs7943316(P=0.0107).Subjects with T allele of rs3805789 or T allele of rs7943316 had higher risks of NIHL than those with the SNP pair of rs3805789-CC and rs7943316-AA(P<0.05).There was an interaction among rs3805789,rs7943316,and kurtosis(P=0.0010).Subjects exposed to complex noise and carrying both rs3805789-CT and rs7943316-TT or rs3805789-CT/TT and rs7943316-AA had higher risks of NIHL than those exposed to steady noise and carrying both rs3805789-CC and rs7943316-AA(P<0.05).The best six-locus model involving NRN1 rs3805789,CAT rs7943316,smoking,video volume,physical exercise,and working pressure for the risk of NIHL was found to be the interaction(P=0.0010).An interaction was also found among smoking,video volume,physical exercise,working pressure,and kurtosis(P=0.0107).Conclusion Concurrence of NRN1 and CAT constitutes a genetic risk factor for NIHL.Complex noise exposure significantly increases the risk of NIHL in subjects with a high genetic risk score.Interactions between genes and lifestyles as well as noise metrics and lifestyles affect the risk of NIHL.

Saturated hydrogen saline protects against noise-induced hearing loss

Objective To study effects of saturated hydrogen saline in preventing noise-induced hearing loss. Methods Fifteen guinea pigs were randomly divided into 3 groups (5 each), group one was for control, group two was treated with normal saline and group three was treated with saturated hydrogen saline, which was given intraperitoneally at 1 hour before noise exposure at 1 ml/100 g. One hundred rounds of impulse noise (157 dB SPL peak) were delivered as noise exposure. Immediately after exposure to impulse noise and on Days 1, 2, 4 and 8 following exposure, auditory brainstem response(ABR) thresholds were measured. Outer hair cell morphological changes and succinate dehydrogenase(SDH) activity were examined on Day 8 post-exposure. Results Immediately after noise exposure, ABR thresholds in saturated hydrogen saline treated animals were lower than the non-treated animals (P < 0.05). Microscopy showed little SDH staining, cell swelling and irregular cell arrangement in the non-treated or normal saline treated animals. Whereas in the saturated hydrogen saline treated animals, there was deep SDH staining with significantly reduced cell loss and more regular cellular arrangement compared to the other two groups. The surviving cells counts was 45.17 ±12.15 for non-treated animals, 44.50 ±10.02 for normal saline treated animals and,116.50±2.38 for animals treated with saturated hydrogen saline. While the count was similar between non-treated and normal saline treated animals, it was significantly higher in saturated hydrogen saline treated animals(P < 0.05). Conclusions Intraperitoneal injection of saturated hydrogen saline appears to protect the cochlea against noise-induced damage.

Noise-induced hearing loss in the 21^(st) century: A research and translational update

Millions of people worldwide are exposed to harmful levels of noise daily in their work and leisure environment. This makes noise-induced hearing loss(NIHL) a major occupational health risk globally. NIHL is the second most common form of acquired hearing loss after agerelated hearing loss and is itself a major contributing factor to presbycusis. Temporary threshold shifts, once thought to be relatively harmless and recoverable, are now known to cause permanent cochlear injury leading to permanent loss of hearing sensitivity. This article reviews the current understanding of the cellular and molecular pathophysiology of NIHL with latest findings from animal models. Therapeutic approaches to protect against or to mitigate NIHL are discussed based on their proposed action against these known mechanisms of cochlear injury. Successes in identifying genes that predispose individuals to NIHL by candidate gene association studies are discussed with matched gene knockout animal models. This links to exciting developments in experimental gene therapy to replace and regenerate lost hair cells and post-noise otoprotective therapies currently being investigated in clinical trials. The aim is to provide new insights into current and projected future strategies to manage NIHL; bench to bedside treatment is foreseeable in the next 5 to 10 years.

Genetically modified pigs:Emerging animal models for hereditary hearing loss

Hereditary hearing loss(HHL),a genetic disorder that impairs auditory function,significantly affects quality of life and incurs substantial economic losses for society.To investigate the underlying causes of HHL and evaluate therapeutic outcomes,appropriate animal models are necessary.Pigs have been extensively used as valuable large animal models in biomedical research.In this review,we highlight the advantages of pig models in terms of ear anatomy,inner ear morphology,and electrophysiological characteristics,as well as recent advancements in the development of distinct genetically modified porcine models of hearing loss.Additionally,we discuss the prospects,challenges,and recommendations regarding the use pig models in HHL research.Overall,this review provides insights and perspectives for future studies on HHL using porcine models.

Modified intratympanic steroid therapy for sudden sensorineural hearing loss via tympanic tube and gelfoam as a salvage treatment

Background: Sudden sensorineural hearing loss(SSNHL) is a prevalent emergency in ear, nose, and throat practice. Previous studies have demonstrated that intratympanic steroid therapy(IST) can serve as a salvage treatment for SSNHL after the failure of systemic steroid therapy(SST).Objective: This study aimed to analyze the efficacy of modified IST involving the insertion of a tympanic tube and gelfoam as a salvage treatment for patients with SSNHL, and to explore its associated factors.Methods: Totally, 74 patients who were aged 22–81 years with SSNHL were enrolled and allocated to either the control group(n = 25) or the treatment group(n = 49) based on their treatment modalities. All patients received SST lasting for at least 7 days. Subsequently, patients in the treatment group, after SST failure, underwent IST twice a week for 2–6 weeks, while the control group did not. Efficacy was assessed by the improvement in pure tone average at the affected frequency at the beginning and end of IST.Results: Hearing improvement in all patients after IST in the treatment group was 9.71 ± 14.84 dB, with significant improvement at affected frequencies(250-8000 Hz) compared with the control group(P < 0.05). The findings indicated the duration from the onset of SSNHL to the beginning of IST as an independent factor for pure tone average improvement after treatment(P = 0.002), whereas age, duration of SST, and time of IST were not(P > 0.05).Conclusion: The modified IST was demonstrated to be a safe and effective method as a salvage treatment for SSNHL. This study explored the efficacy of a modified IST approach, incorporating the utilization of tympanic tubes and gelfoam as key components. The findings underscore the advantages of gelfoam as a strategic drug carrier placed in the round window niche. By minimizing drug loss, extending action time, and increasing perilymph concentration, gelfoam enhances the therapeutic impact of IST, contributing to improved hearing outcomes in patients with SSNHL.

Effect of foot reflexology on an infant with sensorineural hearing loss:A case report

BACKGROUND Our study contributes to the further understanding of the mechanism of foot reflexology.Foot reflexology has been reported to affect hearing recovery,but no physiological evidence has been provided.This lack of evidence hampers the acceptance of the technique in clinical practice.CASE SUMMARY A girl was taken to North Sichuan Medical University Affiliated Hospital for a hearing screen by her parents.Her parents reported that her hearing level was the same as when she was born.The girl was diagnosed with sensorineural hearing loss(SNHL)by a doctor in the otolaryngology department.After we introduced the foot reflexology project,the parents agreed to participate in the experiment.After 6 months of foot reflexology treatment,the hearing threshold of the girl recovered to a normal level,below 30 dB.CONCLUSION Foot reflexology should be encouraged in clinical practice and for families of infants with SNHL.

Navigating Silence: A Comprehensive Review of Parental Roles in the Rehabilitation of Children with Hearing Loss

This narrative literature review delves into the multifaceted realm of parental involvement in the rehabilitation of children with permanent hearing loss. While existing research has made strides in elucidating parental roles in this context, critical gaps persist, necessitating a comprehensive exploration to inform future endeavors. Our review synthesizes a wide array of studies, identifying these gaps and emphasizing the significance of addressing them. Themes emerging from the literature include the varying degrees of parental engagement, the impact of cultural and socio-economic factors, and the challenges faced by families navigating rehabilitation processes. The synthesis of this literature not only highlights the current state of knowledge but also provides a roadmap for future research efforts. By addressing these gaps, we aim to contribute to a more nuanced understanding of parental involvement in the rehabilitation of children with permanent hearing loss, ultimately fostering improved support systems and holistic care for affected families.

Autosomal dominant non-syndromic hearing loss caused by a novel mutation in MYO7A:A case report and review of the literature

BACKGROUND Variants in the MYO7A gene commonly result in Usher syndrome,and in rare cases lead to autosomal dominant non-syndromic deafness(DFNA11).Currently,only nine variants have been reported to be responsible for DFNA11 and their clinical phenotypes are not identical.Here we present a novel variant causing DFNA11 identified in a three-generation Chinese family.CASE SUMMARY The proband was a 53-year-old Han male who presented with post-lingual bilateral symmetrical moderate sensorineural hearing loss.We learned from the patient’s medical history collection that multiple family members also had similar hearing loss,generally occurring around the age of 40.Subsequent investigation by high-throughput sequencing identified a novel MYO7A variant.To provide evidence supporting that this variant is responsible for the hearing loss in the studied family,we performed Sanger sequencing on 11 family members and found that the variant co-segregated with the deafness phenotype.In addition,the clinical manifestation of the 11 affected family members was found to be lateonset bilateral slowly progressive hearing loss,inherited in this family in an autosomal dominant manner.None of the affected family members had visual impairment or vestibular symptoms;therefore,we believe that this novel MYO7A variant is responsible for the rare DFNA11 in this family.CONCLUSION We report a novel variant leading to DFNA11 which further enriches the collection of MYO7A variants,and our review of the nine previous variants that have been identified to cause DFNA11 provides a reference for clinical genetic counseling.

The impact of hearing impairment and noise-induced hearing injury on quality of life in the active-duty military population:challenges to the study of this issue

The objectives of this review were to 1)summarize the available evidence on the impact of hearing loss on quality of life(QOL)among U.S.active-duty service members,2)describe the QOL instruments that have been used to quantify the impact of hearing loss on quality of life,3)examine national population-level secondary databases and report on their utility for studying the impact of hearing loss on QOL among active-duty service members,and 4)provide recommendations for future studies that seek to quantify the impact of hearing loss in this population.There is a lack of literature that addresses the intersection of hearing impairment,the military population,and quality of life measures.For audiological research,U.S.military personnel offer a unique research population,as they are exposed to noise levels and blast environments that are highly unusual in civilian work settings and can serve as a model population for studying the impact on QOL associated with these conditions.This review recommends conducting a study on the active-duty service member population using a measurement instrument suitable for determining decreases in QOL specifically due to hearing loss.

Hidden Hearing Loss: Causes, Current Knowledge, and Future Directions

Introduction: Hidden hearing loss (HHL) is a type of auditory disorder that affects the auditory neural processing and hearing sensitivity in subjects with normal hearing thresholds. Unlike central auditory processing disorders, HHL happens when the cochlea (the peripheral auditory organ) is affected. There are several known risk factors to HHL which includes noise exposure, ototoxic drugs, and peripheral neuropathies, and age. Recent studies have shed light on this type of hearing loss, its etiology, prevalence, and how it can affect the auditory acuity in humans. Methods: This paper covers the current research regarding HHL, its causes, the different mechanisms involved in this disorder, and the diagnosis and potential treatments related to it. We will delve deeply into different researches concerning HHL. 4 articles from 285 were selected focusing on normal hearing individuals with bad speech intelligibility were discussed in this paper. In addition, articles discussing the effects of noise exposure on hearing impaired individuals were not considered as this study solely aims to focus on normal hearing sensitivity individuals with HHL, resulting in 4 articles from 285. Results: Numerous literatures over the decades have suggested that HHL is due to the degeneration of cochlear ribbon synapses, or hair cells synapses without hair cell damage. Their association with HHL was noted several times through this study, whether we were studying the effect of noise exposure, of age, or of ototoxicity. In all cases, no significant hair cell damage was observed, and normal thresholds were recovered. However, a decline in the amplitude of Auditory Brainstem Response (ABR) peak I from auditory nerve (AN) responses in noise exposed subjects and a decline in compound action potential (CAP) was measured when certain drugs were applied to the round window of Guinea pigs. Conclusion: Most studies, have proven that cochlear synaptophysin is the major contributor to noise induced, age, and ototoxic related HHL. There are several audiometric tests that were used to help identify HHL including Puretone audiometry in background noise, ABR, CAP, Distortion Product Otoacoustic Emission (DPOAE).

Age-related hearing loss accelerates the decline in fast speech comprehension and the decompensation of cortical network connections

Patients with age-related hearing loss face hearing difficulties in daily life.The causes of age-related hearing loss are complex and include changes in peripheral hearing,central processing,and cognitive-related abilities.Furthermore,the factors by which aging relates to hearing loss via changes in audito ry processing ability are still unclear.In this cross-sectional study,we evaluated 27 older adults(over 60 years old) with age-related hearing loss,21 older adults(over 60years old) with normal hearing,and 30 younger subjects(18-30 years old) with normal hearing.We used the outcome of the uppe r-threshold test,including the time-compressed thres h old and the speech recognition threshold in noisy conditions,as a behavioral indicator of auditory processing ability.We also used electroencephalogra p hy to identify presbycusis-related abnormalities in the brain while the participants were in a spontaneous resting state.The timecompressed threshold and speech recognition threshold data indicated significant diffe rences among the groups.In patients with age-related hearing loss,information masking(babble noise) had a greater effect than energy masking(speech-shaped noise) on processing difficulties.In terms of resting-state electroencephalography signals,we observed enhanced fro ntal lobe(Brodmann’s area,BA11) activation in the older adults with normal hearing compared with the younger participants with normal hearing,and greater activation in the parietal(BA7) and occipital(BA19) lobes in the individuals with age-related hearing loss compared with the younger adults.Our functional connection analysis suggested that compared with younger people,the older adults with normal hearing exhibited enhanced connections among networks,including the default mode network,sensorimotor network,cingulo-opercular network,occipital network,and frontoparietal network.These results suggest that both normal aging and the development of age-related hearing loss have a negative effect on advanced audito ry processing capabilities and that hearing loss accele rates the decline in speech comprehension,especially in speech competition situations.Older adults with normal hearing may have increased compensatory attentional resource recruitment represented by the to p-down active listening mechanism,while those with age-related hearing loss exhibit decompensation of network connections involving multisensory integration.

Various aspects of hearing loss in newborns:A narrative review

Hearing loss is considered the most common birth defect.The estimated prevalence of moderate and severe hearing loss in a normal newborn is 0.1%-0.3%,while the prevalence is 2%-4%in newborns admitted to the newborn intensive care unit.Neonatal hearing loss can be congenital(syndromic or nonsyndromic)or acquired such as ototoxicity.In addition,the types of hearing loss can be conductive,sensorineural,or mixed.Hearing is vital for the acquisition of language and learning.Therefore,early detection and prompt treatment are of utmost importance in preventing the unwanted sequel of hearing loss.The hearing screening program is mandatory in many nations,especially for high-risk newborns.An automated auditory brainstem response test is used as a screening tool in newborns admitted to the newborn intensive care unit.Moreover,genetic testing and screening for cytomegalovirus in newborns are essential in identifying the cause of hearing loss,particularly,mild and delayed onset types of hearing loss.We aimed to update the knowledge on the various aspects of hearing loss in newborns with regard to the epidemiology,risk factors,causes,screening program,investigations,and different modalities of treatment.

The portrayal of hearing loss information in online Mandarin videos

Background/purpose:With increasing accessibility to the Internet,patients frequently use the Internet for hearing healthcare information.No study has examined the information about hearing loss available in the Mandarin language on online video-sharing platforms.The study’s primary purpose is to investigate the content,source,understandability,and actionability of hearing loss information in the Mandarin language’s one hundred most popular online videos.Method:In this project,publicly accessible online videos were analyzed.One hundred of the most popular Mandarin-language videos about hearing loss were identified(51 videos on YouTube and 49 on the Bilibili video-sharing platform).They were manually coded for different popularity metrics,sources,and content.Each video was also rated using the Patient Education Materials Assessment Tool for Audiovisual Materials(PEMAT-AV)to measure the understandability and actionability scores.Results:The video sources were classified as either media(n=36),professional(n=39),or consumer(n=25).The videos covered various topics,including symptoms,consequences,and treatment of hearing loss.Overall,videos attained adequate understandability scores(mean=73.6%)but low(mean=43.4%)actionability scores.Conclusions:While existing online content related to hearing loss is quite diverse and largely understandable,those videos provide limited actionable information.Hearing healthcare professionals,media,and content creators can help patients better understand their conditions and make educated hearing healthcare decisions by focusing on the actionability information in their online videos.

Intratympanic injection of hydrogel nanodrug for the prevention and treatment of sensorineural hearing loss

Safe and efficient drug delivery to the inner ear has always been the focus of prevention and treatment of sensorineural deafness.The rapid development of nanodrug delivery systems based on hydrogel has provided a new opportunity.Among them,thermo-sensitive hydrogels promote the development of new dosage form for intratympanic injection.This smart biomaterial could transform to semisolid phase when the temperature increased.Thermo-sensitive hydrogel nanodrug delivery system is expected to achieve safe,efficient,and sustained inner ear drug administration.This article introduces the key techniques and the latest progress in this field.

Subclinical hearing loss associated with aging

Objective:Contribute to clarifying the existence of subclinical hearing deficits associated with aging.Design:In this work,we study and compare the auditory perceptual and electrophysiological performance of normal-hearing young and adult subjects(tonal audiometry,high-frequency tone threshold,a triplet of digits in noise,and click-evoked auditory brainstem response).Study sample:45 normal hearing volunteers were evaluated and divided into two groups according to age.27 subjects were included in the“young group”(mean 22.1 years),and 18 subjects(mean 42.22 years)were included in the“adult group.”Results:In the perceptual tests,the adult group presented significantly worse tonal thresholds in the high frequencies(12 and 16 kHz)and worse performance in the digit triplet tests in noise.In the electrophysiological test using the auditory brainstem response technique,the adult group presented significantly lower I and V wave amplitudes and higher V wave latencies at the supra-threshold level.At the threshold level,we observed a significantly higher latency in wave V in the adult group.In addition,in the partial correlation analysis,controlling for the hearing level,we observed a relationship(negative)between age and speech in noise performance and high-frequency thresholds.No significant association was observed between age and the auditory brainstem response.Conclusion:The results are compatible with subclinical hearing loss associated with aging.

Effect of minocycline and its nano-formulation on central auditory system in blast-induced hearing loss rat model

Blast injuries are common among the military service members and veterans.One of the devastating effects of blast wave induced TBI is either temporary or permanent hearing loss.Treating hearing loss using minocycline is restricted by optimal drug concentration,route of administration,and its half-life.Therefore,therapeutic approach using novel therapeutic delivery method is in great need.Among the different delivery methods,nanotechnology-based drug delivery is desirable,which can achieve longer systemic circulation,pass through some biological barriers and specifically targets desired sites.The current study aimed to examine therapeutic effect of minocycline and its nanoparticle formulation in moderate blast induced hearing loss rat model through central auditory system.The I.v.administered nanoparticle at reduced dose and frequency than regularly administered toxic dose.After moderate blast exposure,rats had hearing impairment as determined by ABR at 7-and 30-days post exposure.In chronic condition,free minocycline also showed the significant reduction in ABR threshold.In central auditory system,it is found in this study that minocycline nanoparticles ameliorate excitation in inferior colliculus;and astrocytes and microglia activation after the blast exposure is reduced by minocycline nanoparticles administration.The study demonstrated that in moderate blast induced hearing loss,minocycline and its nanoparticle formulation exhibited the optimal therapeutic effect on the recovery of the ABR impairment and a protective effect through central auditory system.In conclusion,targeted and non-targeted nanoparticle formulation have therapeutic effect on blast induced hearing loss.