Auditory Organ Research Articles

Histone Demethylase PHF8 Is Required for the Development of the Zebrafish Inner Ear and Posterior Lateral Line.

Histone demethylase PHF8 is crucial for multiple developmental processes, and hence, the awareness of its function in developing auditory organs needs to be increased. Using in situ hybridization (ISH) labeling, the mRNA expression of PHF8 in the zebrafish lateral line system and otic vesicle was monitored. The knockdown of PHF8 by morpholino significantly disrupted the development of the posterior lateral line system, which impacted cell migration and decreased the number of lateral line neuromasts. The knockdown of PHF8 also resulted in severe malformation of the semicircular canal and otoliths in terms of size, quantity, and position during the inner ear development. The loss of function of PHF8 also induced a defective differentiation in sensory hair cells in both lateral line neuromasts and the inner ear. ISH analysis of embryos that lacked PHF8 showed alterations in the expression of many target genes of several signaling pathways concerning cell migration and deposition, including the Wnt and FGF pathways. In summary, the current findings established PHF8 as a novel epigenetic element in developing auditory organs, rendering it a potential candidate for hearing loss therapy.

Distribution of Kv3 Subunits in Cochlear Afferent and Efferent Nerve Fibers Implies Distinct Role in Auditory Processing.

Kv3 family K+ channels, by ensuring speedy repolarization of action potential, enable rapid and high frequency neuronal firing and high precision temporal coding of auditory information in various auditory synapses in the brain. Expression of different Kv3 subtypes within the auditory end organ has been reported. Yet, their precise role at the hair cell synaptic transmission has not been fully elucidated. Using immunolabeling and confocal microscopy we examined the expression pattern of different Kv3 family K+ channel subunits in the nerve fibers innervating the cochlear hair cells. Kv3.1b was found in NKA-positive type 1 afferent fibers, exhibiting high signal intensity at the cell body, the unmyelinated dendritic segment, first heminode and nodes of Ranvier. Kv3.3 signal was detected in the cell body and the unmyelinated dendritic segment of NKA-positive type 1 afferent fibers but not in peripherin-positive type 2 afferent. Kv3.4 was found in ChAT-positive LOC and MOC efferent fibers as well as peripherin-positive type 2 afferent fibers. Such segregated expression pattern implies that each Kv3 subunits participate in different auditory tasks, for example, Kv3.1b and Kv3.3 in ascending signaling while Kv3.4 in feedback upon loud noise exposure.

Influence of music and color spectrum on the nervous system of humans and animals

Several years ago, I published articles in Russian and German languages about the influence of music on humans and animals. Then, in 1897, I again published in Russian The Influence of Music on Man and Animals. In this 2nd edition there is a more detailed description of the structure of the auditory organ, the human larynx and the hearing aid of some animals; a few remarks about notation, about more well-known musical instruments, about the meaning of music in educational, medical and social relations.

NOISE POLLUTION IN A REGIONAL TOWN IN THE SOUTHERN BULGARIA

Noise Pollution in a Regional Town in the Southern BulgariaJeni Staykova1, Manoela Georgiva2, Rositsa Chilingirova3MU-Sofia, Council of Ministers - Republic of Bulgaria, RHI-KardzhaliNoise is a major adverse factor for health in urbanized areas, influencing mainly the auditory organ, nervous and digestive systems.The objective of the research study is to determine the noise pollution in Kardzhali and to suggest appropriate measures to optimise the environment.Materials and methods. The noise level measurement is carried out at 15 points, close to intensive road and rail transport, to industrial sources and areas subject to noise protection. A measuring method and technical equipment of Bruel & Kjaer were applied subject to an ordinance of the Ministry of Health. Results. 55.6% of noise levels are above the limit values in the respective territories. According to the standards these are 44.4%. Levels within the range of 58-62 dB(A) are registered in one point, 63-67 dB(A) in three points, and 68-72 dB (S) - in five points. Compared to 2018 (67.8% above the reference), the results were better.Conclusions. To optimize the acoustic environment, architectural, urban, engineering, technical and organizational and hygienic measures must be undertaken by all interested parties. The main priority for the reduction of noise pollution in Kardzhali is the construction of a ring road.Keywords: noise pollution, health, acoustic environment, protection measures

Does the short-term exposure to radiofrequency electromagnetic field originating from mobile phone affect auditory functions as measured by Acoustic Admittance and Evoked Otoacoustic Emission tests?

ABSTRACT Background Mobile phones constitute an important source of radiofrequency electromagnetic field (RF-EMF) for humans. Taking into account high sensitivity of sensory hair cells of the inner ear to endogenous and exogenous agents, the potential impact of mobile phone usage on auditory organs is of particular interest. Aim The aim of the study was to evaluate the impact of short-term exposure to RF-EMF generated by a mobile phone during 15-minute simulated phone call on human hearing as measured by Transient Evoked Otoacoustic Emission (TEOAE) and Acoustic Admittance Testing (AAT). Material and methods Within-subject study was performed on 23 healthy volunteers. All of the participants underwent TEOAE and AAT before and immediately after 15-minute simulated phone call with the use of a standard, modern smartphone. Analyzed parameters included: static compliance of tympanic membrane, middle ear pressure, ipsi- and contralateral acoustic reflex thresholds and percentage of signal reproducibility in TEOAE for exposed and non-exposed ear. Additionally, the results were compared in subgroups distinguished basing on self-reported sensitivity to RF-EMF originating from mobile phones. Results No statistically significant differences were identified between results of TEOAE and AAT before and after exposure, both in exposed and non-exposed ear. The results of EMF sensitive and non-sensitive subjects were comparable in all performed tests. Conclusions Short-term exposure to mobile phone electromagnetic field did not influence auditory functions as measured by Evoked Otoacoustic Emission test and Acoustic Admittance Testing.

Systematic Transcriptome Analysis of Noise-Induced Hearing Loss Pathogenesis Suggests Inflammatory Activities and Multiple Susceptible Molecules and Pathways.

Noise-induced hearing loss (NIHL) is characterized by damage to cochlear neurons and associated hair cells; however, a systematic evaluation of NIHL pathogenesis is still lacking. Here, we systematically evaluated differentially expressed genes of 22 cochlear samples in an NIHL mouse model. We performed Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis and weighted gene co-expression network analysis (WGCNA). Core modules were detected using protein–protein interactions and WGCNA with functional annotation, diagnostic value evaluation, and experimental validation. Pooled functional annotation suggested the involvement of multiple inflammatory pathways, including the TNF signaling pathway, IL-17 signaling pathway, NF-kappa B signaling pathway, rheumatoid arthritis, and p53 signaling pathway. The core modules suggested that responses to cytokines, heat, cAMP, ATP, mechanical stimuli, and immune responses were important in NIHL pathogenesis. These activities primarily occurred on the external side of the plasma membrane, the extracellular region, and the nucleus. Binding activities, including CCR2 receptor binding, protein binding, and transcription factor binding, may be important. Additionally, the hub molecules with diagnostic value included Relb, Hspa1b, Ccl2, Ptgs2, Ldlr, Plat, and Ccl17. An evaluation of Relb and Hspa1b protein levels showed that Relb was upregulated in spiral ganglion neurons, which might have diagnostic value. In conclusion, this study indicates that the inflammatory response is involved in auditory organ changes in NIHL pathogenesis; moreover, several molecules and activities have essential and subtle influences that have translational potential for pharmacological intervention.

Tinnitus rat model generated by laser-induced shock wave; a platform for analyzing the central nervous system after tinnitus generation

ObjectiveTinnitus is a phantom auditory sensation, which is mainly triggered by dysfunction of the peripheral auditory organ, such as cochlear disorders. Additionally, the central nervous system, specifically the limbic system, plays a crucial role in the generation and exacerbation of tinnitus. Therefore, to analyze the hypothesis that tinnitus has strong and specific association with the plastic changes in the limbic system, we assessed the neuronal plastic changes in the limbic system, including the hippocampus and the amygdala, in rats with single-sided tinnitus. MethodsThe cochlear damage was achieved by irradiating the cochlea with laser-induced shock wave (LISW). While both hearing loss and tinnitus were confirmed after exposure of rats to LISW, the degree of tinnitus was objectively measured using gap detection behavioral tests. Following the generation of hearing loss and tinnitus, plastic changes in the neurons of the limbic system were confirmed using a molecular marker (activity regulated cytoskeleton-associated protein; Arc). ResultsWhile the expression level of Arc-positive cells in the hippocampal CA1 showed an obvious increase in the hearing loss and tinnitus groups, a significant difference was found between the tinnitus and the control groups. In the dentate gyrus, although the largest number of Arc-positive cells was observed in the tinnitus group, there were no significant differences between the numbers of cells in the hearing loss and tinnitus groups compared to that in the control group. ConclusionAlthough a significant increase of Arc-positive cells in the hippocampal CA1 was observed between the tinnitus group and control, no obvious tendencies of Arc-positive cells in the limbic system were observed between the rats with and without tinnitus behavior.

Let-7 miRNAs inhibit CHD7 expression and control auditory-sensory progenitor cell behavior in the developing inner ear.

The evolutionarily conserved lethal-7 (let-7) microRNAs (miRNAs) are well-known activators of proliferative quiescence and terminal differentiation. However, in the murine auditory organ, let-7g overexpression delays the differentiation of mechano-sensory hair cells (HCs). To address whether the role of let-7 in auditory-sensory differentiation is conserved among vertebrates, we manipulated let-7 levels within the chicken auditory organ: the basilar papilla. Using a let-7 sponge construct to sequester let-7 miRNAs, we found that endogenous let-7 miRNAs are essential for limiting the self-renewal of HC progenitor cells. Furthermore, let-7b overexpression experiments revealed that, similar to mice, higher than normal let-7 levels slow/delay HC differentiation. Finally, we identify CHD7, a chromatin remodeler, as a candidate for mediating the repressive function of let-7 in HC differentiation and inner ear morphogenesis. Our analysis uncovered an evolutionarily conserved let-7-5p-binding site within the chicken Chd7 gene and its human and murine homologs, and we show that let-7g overexpression in mice limits CHD7 expression in the developing inner ear, retina and brain. Haploinsufficiency of CHD7 in humans causes CHARGE syndrome and attenuation of let-7 function may be an effective method for treating CHD7 deficiency.

P‐208: Late‐News‐Poster: Interdisciplinary Research on Acoustic and Human Cognitive Characteristics of Flat‐Panel TVs: Front‐Firing Exciter Speaker Characteristic

Technological advances in the display industry have allowed organic light‐emitting diode panel manufacturers to create ultra‐wider‐screen, high‐picture‐quality, high‐sound‐quality TVs. In the previous research, we have been studied the characteristics of the sound on the screen directly by excite speaker, with the panel of OLED. Unlike LCD, the OLED emits light and composes pictures without complex sheets such as BLU so that the panel can play the role of a diaphragm of a general dynamic speaker.Sound is free to propagate by the vibration of the air. And this air vibration can be information or noise. In this case, when the information is used, the sound is the information required by the listener, and when the opposite listener is not needed or not desired, the noise may be referred to. In addition, the sound is perceived through human auditory organs. At this time, excessively loud volume causes noise‐induced hearing loss. Furthermore, rather degrades information transmission. Depending on the wave motion characteristics of the sound, the phenomenon of refraction, reflection, diffraction occurs, and forms a sound field. As shown in Fig. 1 and Fig. 2, the sound field is distributed differently according to the ordinary dynamic speaker system and exciter speaker system. It is the same thing that occurs in a speaker, but as it propagates, it is different from being concentrated or evenly spread in one place by the effects of refraction and reflection. When the sound is aggregated, the sound quality may be improved by interference between frequencies, but the resolution is often lowered. That is, the down‐firing sound by the existing dynamic speaker has low sound intelligibility. On the other hand, the proposed exciter speaker spreads evenly around the sound sourced directly from the center of the screen and has less influence of the reflected sound source, thus including the information of the original sound well.As shown in Figures 1 and 2, the sound quality of TV sets is also different. Cognitive analysis was performed through listening analysis. Over 150 people watched the same video and conducted a survey. The experiment was to watch TV sitting on the front and side, a group of about ten people at a time. The videos used in the experiments utilized news, classical music, and pop music, and alternately listened and tested for about 30 seconds. After watching the audience, they responded to the cognitive differences in sound quality. The questionnaire asks three kinds of questions. The analysis was performed by factor analysis, reliability analysis, and T‐test. The exploratory factor analysis and reliability analysis results have been fully validated. Cronbach's alpha is above 0.8, and the results are highly reliable. In the T‐test analysis, the t value was significantly obtained as ‐8.684. The sound quality of the two TV sets is different, which means that the average of the indirect sound TV(down‐firing) set is 3.860, and that of the direct sound TV(exciter speaker) set is 4.528, which means the clarity of the direct sound TV set is high.Audiovisual is an essential component of information delivery. The technology of panel makers is improved, and image quality can go beyond HD to achieve ultra‐high resolution of 8K. Sound is also developing through exciter speakers. In this study, Interdisciplinary research was conducted on the information transmission and sound quality of moving images through acoustic and cognitive analysis of down‐ and front‐firing sound sources. In acoustic analysis, the conventional dynamic method is reflected, and the formation of sound fields is disadvantageous. Cognitive analysis showed that the direct sound was easy to understand and accurate. In the future, we will conduct additional studies to improve the objective and subjective sound quality by conducting acoustic and cognitive analysis studies according to various spatial conditions.

Preventive hearing tests in workers exposed to noise and organic solvents

Robust evidence confirms that occupational exposures to organic solvents are ototoxic and can aggravate the effects of noise on the auditory organ. Accordingly, Directive 2003/10/EC of the European Parliament and of the Council recommends that in assessing the risk of occupational hearing loss, the interaction of noise and organic solvents to hearing should be taken into account. Given that no prophylactic recommendations have been established to date, this study is intended to provide physicians with guidance in conducting audiometric tests in workers exposed to noise and organic solvents. The paper discusses the biological effects of noise and organic solvents on the auditory organ and current possibilities of estimating the risk of hearing loss due to isolated exposures to solvents, as well as combined exposures to these chemicals and noise. The scope of medical examination and the significance of individual hearing tests, such as pure-tone audiometry, impedance audiometry, auditory brainstem responses, speech in quiet and speech in noise audiometry, and dichotic digit test, in the diagnostics of solvent-induced hearing loss are presented. An algorithm for conducting hearing tests in workers exposed to organic solvents, and co-exposed to noise and organic solvents, has been proposed depending on the concentration of solvents and noise level. Shown also is the necessity to perform annual audiometric testing in all workers exposed to organic solvents whose concentration in the air exceeds values safe for hearing. In workers exposed to noise and organic solvents, audiometric examinations should be mandatory in all subjects in whom the level of noise exceeds the lower action level defined by Directive 2003/10/EC, which is LEX,8h = 80 dB. Taking into account the detrimental effects of organic solvents to central auditory pathways, in addition to pure-tone audiometry, speech audiometry (preferentially speech in noise) should be included. The introduction of preventive audiometric tests in workers exposed to organic solvents, along with an extension of indications and the scope of hearing tests in workers co-exposed to noise and solvents, is a prerequisite for effective prevention of occupational hearing loss in these professional groups. Med Pr. 2020;71(4):493-505.

Ectopic expression of ROR1 prevents cochlear hair cell loss in guinea pigs with noise-induced hearing loss.

Noise‐induced hearing loss (NIHL) is one of the most frequent disabilities in industrialized countries. Evidence shows that hair cell loss in the auditory end organ is responsible for the majority of various ear pathological conditions. The functional roles of the receptor tyrosine kinase ROR1 have been underscored in various tumours. In this study, we evaluated the ability of ROR1 to influence cochlear hair cell loss of guinea pigs with NIHL. The NIHL model was developed in guinea pigs, with subsequent measurement of the auditory brainstem response (ABR). Gain‐of‐function experiments were employed to explore the role of ROR1 in NIHL. The interaction between ROR1 and Wnt5a and their functions in the cochlear hair cell loss were further analysed in response to alteration of ROR1 and Wnt5a. Guinea pigs with NIHL demonstrated elevated ABR threshold and down‐regulated ROR1, Wnt5a and NF‐κB p65. The up‐regulation of ROR1 was shown to decrease the cochlear hair cell loss and the expression of pro‐apoptotic gene (Bax, p53) in guinea pig cochlea, but promoted the expression of anti‐apoptotic gene (Bcl‐2) and the fluorescence intensity of cleaved‐caspase‐3. ROR1 interacted with Wnt5a to activate the NF‐κB signalling pathway through inducing phosphorylation and translocation of p65. Furthermore, Wnt5a overexpression decreased the cochlear hair cell loss. Collectively, this study suggested the protection of overexpression of ROR1 against cochlear hair cell loss in guinea pigs with NIHL via the Wnt5a‐dependent NF‐κB signalling pathway.

Organ of Corti size is governed by Yap/Tead-mediated progenitor self-renewal

Precise control of organ growth and patterning is executed through a balanced regulation of progenitor self-renewal and differentiation. In the auditory sensory epithelium-the organ of Corti-progenitor cells exit the cell cycle in a coordinated wave between E12.5 and E14.5 before the initiation of sensory receptor cell differentiation, making it a unique system for studying the molecular mechanisms controlling the switch between proliferation and differentiation. Here we identify the Yap/Tead complex as a key regulator of the self-renewal gene network in organ of Corti progenitor cells. We show that Tead transcription factors bind directly to the putative regulatory elements of many stemness- and cell cycle-related genes. We also show that the Tead coactivator protein, Yap, is degraded specifically in the Sox2-positive domain of the cochlear duct, resulting in down-regulation of Tead gene targets. Further, conditional loss of the Yap gene in the inner ear results in the formation of significantly smaller auditory and vestibular sensory epithelia, while conditional overexpression of a constitutively active version of Yap, Yap5SA, is sufficient to prevent cell cycle exit and to prolong sensory tissue growth. We also show that viral gene delivery of Yap5SA in the postnatal inner ear sensory epithelia in vivo drives cell cycle reentry after hair cell loss. Taken together, these data highlight the key role of the Yap/Tead transcription factor complex in maintaining inner ear progenitors during development, and suggest new strategies to induce sensory cell regeneration.

Pre-exposure to Lower-Level Noise Mitigates Cochlear Synaptic Loss Induced by High-Level Noise.

The auditory sensory organs appear to be less damaged by exposure to high-level noise that is presented after exposure to non-traumatizing low-level noise. This phenomenon is known as the toughening or conditioning effect. Functionally, it is manifested by a reduced threshold shift, and morphologically by a reduced hair cell loss. However, it remains unclear whether prior exposure to toughening noise can mitigate the synaptic loss induced by exposure to damaging noise. Since the cochlear afferent synapse between the inner hair cells and primary auditory neurons has been identified as a novel site involved in noise-induced cochlear damage, we were interested in assessing whether this synapse can be toughened. In the present study, the synaptic loss was induced by a damaging noise exposure (106 dB SPL) and compared across Guinea pigs who had and had not been previously exposed to a toughening noise (85 dB SPL). Results revealed that the toughening noise heavily reduced the synaptic loss observed 1 day after exposure to the damaging noise. Although it was significant, the protective effect of the toughening noise on permanent synaptic loss was much smaller. Compared with cases in the control group without noise exposure, coding deficits were seen in both toughened groups, as reflected in the compound action potential (CAP) by signals with amplitude modulation. In general, the pre-exposure to the toughening noise resulted in a significantly reduced synaptic loss by the high-level noise. However, this morphological protection was not accompanied by a robust functional benefit.

Zika virus can directly infect and damage the auditory and vestibular components of the embryonic chicken inner ear.

Sensorineural hearing loss is an understudied consequence of congenital Zika syndrome, and balance disorders are essentially unreported to date. Also lacking is information about the susceptibility and the pathogenesis of the developing inner ear following Zika virus (ZIKV) exposure. To address this, ZIKV was delivered directly into the otic cup/otocyst of chicken embryos and infection of inner ear tissues was evaluated using immunohistochemistry. After injections on embryonic days 2 to 5, ZIKV infection was observed in 90% of the samples harvested 2 to 8 days later; however, the degree of infection was highly variable across individuals. ZIKV was detected in all regions of the inner ear, associated ganglia, and in the surrounding periotic mesenchyme. Detection of virus peaked earlier in the ganglion and vestibular compartments, and later in the cochlea. ZIKV infection increased cell death robustly in the auditory ganglion, and modestly in the auditory sensory organ. Macrophage accumulation was found to overlap with dense viral infection in some tissues. Additionally, dysmorphogenesis of the semicircular canals and ganglion was observed for a subset of injection conditions. This article presents evidence of direct ZIKV infection of developing inner ear epithelium and shows previously unknown inner ear dysmorphogenesis phenotypes.

The acquisition of positional information in the developing cochlea

The sensory epithelium of the mammalian murine auditory organ, the organ of Corti, is an exquisite example of how specialized asymmetry dictates auditory function. Across the radial axis, the organ consists of three rows of outer hair cells to one row of inner hair cells, which are innervated by efferent and afferent neurons. The mechanosensory inner hair cells that reside in the neural compartment detect sound whereas the outer hair cells in the abneural compartment modulate sound levels. A complex combination of spatio‐temporal signaling inputs across the radial axis endows cells with positional information to take on specific cell fates.The Wnt and Bmp pathways are two potential signaling mechanisms that influence this radial asymmetry in an opposing manner. We analyzed the requirement of the Bmp pathway for setting up cochlear patterning. Smad4 cKOs showed a loss of the abneural compartment. Prolonged Bmp inhibition decreased the formation of the abneural compartment and outer hair cells. Bmp was required for determining the abneural boundary of the sensory domain. Immediately after hair cell differentiation, Bmp signaling was no longer required. Bmp is necessary, but not sufficient for patterning the entire epithelium. Activation of the Wnt pathway leads to a selective expansion of the neural compartment and inner hair cells. This selective neural expansion was also conserved in the chicken cochlea. Signaling crosstalk of these pathways in a spatiotemporal manner is necessary for proper patterning of the organ of Corti.Support or Funding Information R21DC016376R01DC002756R01GM132501

Infrasonic hearing in birds: a review of audiometry and hypothesized structure-function relationships.

The perception of airborne infrasound (sounds below 20 Hz, inaudible to humans except at very high levels) has been documented in a handful of mammals and birds. While animals that produce vocalizations with infrasonic components (e.g. elephants) present conspicuous examples of potential use of infrasound in the context of communication, the extent to which airborne infrasound perception exists among terrestrial animals is unclear. Given that most infrasound in the environment arises from geophysical sources, many of which could be ecologically relevant, communication might not be the only use of infrasound by animals. Therefore, infrasound perception could be more common than currently realized. At least three bird species, each of which do not communicate using infrasound, are capable of detecting infrasound, but the associated auditory mechanisms are not well understood. Here we combine an evaluation of hearing measurements with anatomical observations to propose and evaluate hypotheses supporting avian infrasound detection. Environmental infrasound is mixed with non-acoustic pressure fluctuations that also occur at infrasonic frequencies. The ear can detect such non-acoustic pressure perturbations and therefore, distinguishing responses to infrasound from responses to non-acoustic perturbations presents a great challenge. Our review shows that infrasound could stimulate the ear through the middle ear (tympanic) route and by extratympanic routes bypassing the middle ear. While vibration velocities of the middle ear decline towards infrasonic frequencies, whole-body vibrations - which are normally much lower amplitude than that those of the middle ear in the 'audible' range (i.e. >20 Hz) - do not exhibit a similar decline and therefore may reach vibration magnitudes comparable to the middle ear at infrasonic frequencies. Low stiffness in the middle and inner ear is expected to aid infrasound transmission. In the middle ear, this could be achieved by large air cavities in the skull connected to the middle ear and low stiffness of middle ear structures; in the inner ear, the stiffness of round windows and cochlear partitions are key factors. Within the inner ear, the sizes of the helicotrema and cochlear aqueduct are expected to play important roles in shunting low-frequency vibrations away from low-frequency hair-cell sensors in the cochlea. The basilar papilla, the auditory organ in birds, responds to infrasound in some species, and in pigeons, infrasonic-sensitive neurons were traced back to the apical, abneural end of the basilar papilla. Vestibular organs and the paratympanic organ, a hair cell organ outside of the inner ear, are additional untested candidates for infrasound detection in birds. In summary, this review brings together evidence to create a hypothetical framework for infrasonic hearing mechanisms in birds and other animals.

Impact of Noise Exposure on the Reliability of the Human Factor in the Production Hall

The subject of the paper is the analysis of the impact of noise exposure of human reliability in a production workplace with a high noise load. Long-term monitoring of the effects of low frequencies on human hearing has been shown to be the risk of harm to human health caused by this effect. The negative effects of noise on human health manifest themselves primarily in the areas of the human auditory organ, permanent and incurable disorders. The paper proposes a method to assess the reliability of the human factor in noise exposure operations. Practical measurement of noise exposure was carried out in heavy machinery operation, welding workplace. The risk assessment was carried out using the TESEO method. Based on the assessment, possible human errors in the operation were identified.

Retrospective investigation on explosive hearing loss of injured persons in explosion accidents involving a steel enterprise

Objective: Through the investigation of the injured persons in explosion accidents, the impact of wearing the ear protectors device (anti-noise earplugs) on the auditory organs and hearing loss of the injured person was understood, which could provide reference for the clinical diagnosis, treatment and prevention of the explosive hearing impairment. Methods: A retrospective survey was conducted on 39 directly injured persons who were injured in 23 explosion accidents involving a steel plant from 1990 to 2016 as the explosive hearing loss, taking the time of the patient＇s injury and 3-6 months after the injury as the time of investigation and evidence collection, and according to whether to wear the ear protectors device for group comparison and statistical analysis. Results: There was no significant difference between the two groups in hearing loss, tinnitus, earache, headache, some patients with dizziness and craniocerebral injury, regardless of whether the injured person wore anti-noise earplugs or not (P=0.444-1) , the shock (coma) patients in the non-protected group were more common (34.8%, 8/23) , and the difference was statistically significant (P=0.012) ; Although auricle injury was detected in both groups and there was no significant difference between the two groups (P=1) , but the external ear canal injury, tympanic membrane perforation were more common in the non-protected group, and there was no external ear canal and tympanic membrane perforation in the wearing earplug group, and the difference between the two groups was significant (P=0.000) . After 3-6 months, the rehabilitation of auditory system and other symptoms in patients showed that the hearing loss, tinnitus, earache, headache, dizziness and other symptoms all disappeared in patients wearing earplugs, while the above symptoms in the non-protected group were improved but more persisted, and the difference between the two groups was statistically significant (P=0.000-0.012) , and there was no significant difference in rehabilitation conditions such as craniocerebral injury between the two groups (P=1) ; There were patients with unhealed auricle injury in both groups in 3-6 months after the injury, and there was no significant difference between the two groups (P=1) , however, in the non-protected group, 69.57% (16/23) of the patients with external auditory canal injury were still unhealed and none of the patients with tympanic membrane perforation recovered, and the difference between the two groups was obvious (P=0.000~0.001) ; Pure tone air conduction examination showed that the hearing of the earplugs wearers was well recovered at the time of the explosion, while irreversible hearing impairment was common in the non-protective group, the difference was statistically significant (P=0.000) . Conclusion: Ear protector plays an important role in protecting the auditory organs and hearing of workers in explosion accident, and it is an effective protective measure to prevent and reduce the damage of external ear canal, perforation of tympanic membrane and explosive hearing loss caused by explosion accidents.

Effects of acute noise exposure on DNA damage response genes in the cochlea, cortex, heart and liver

Noise as a systemic stressor induces various organ dysfunctions and the underlying molecular pathology is unknown. Previous studies have shown that noise exposure results in the accumulation of DNA damage in auditory and non-auditory organs. The DNA damage response (DDR) is a global protective mechanism that plays a critical role in maintaining DNA integrity. However, the role of DDR genes in noise induced systemic (non-auditory) pathology has not been investigated. The current pilot study was designed to test the hypothesis that an acute noise exposure would alter the normal expression of DDR genes (e.g., ATM, p53 & XPC) in auditory (cochlea) and non-auditory organs, such as the cortex, heart and liver. Mice were used as subjects in this study and consisted of a baseline group, a one-hour noise exposure (@105 dB) group, and a four-hour noise exposure (@105 dB) group. ATM, p53 and XPC expression levels were quantified through end-point polymerize chain reactions. The current study demonstrated that noise exposure failed to elicit statistically significant changes in DDR genes (relative to baseline) across the various organs. The failure of the cochlea, heart, cortex and liver to upregulate protective DDR genes during acute noise exposure might help to explain their susceptibility to noise-induced DNA damage. This suggests that, biomedical interventions to upregulate DDR genes may need to be implemented before noise exposure or during the early stages of noise exposure.

A new method of recording from the giant fiber of Drosophila melanogaster shows that the strength of its auditory inputs remains constant with age.

There have been relatively few studies of how central synapses age in adult Drosophila melanogaster. In this study we investigate the aging of the synaptic inputs to the Giant Fiber (GF) from auditory Johnston's Organ neurons (JONs). In previously published experiments an indirect assay of this synaptic connection was used; here we describe a new, more direct assay, which allows reliable detection of the GF action potential in the neck connective, and long term recording of its responses to sound. Genetic poisoning using diphtheria toxin expressed in the GF with R68A06-GAL4 was used to confirm that this signal indeed arose from the GF and not from other descending neurons. As before, the sound-evoked action potentials (SEPs) in the antennal nerve were recorded via an electrode inserted at the base of the antenna. It was noted that an action potential in the GF elicited an antennal twitch, which in turn evoked a mechanosensory response from the JONs in the absence of sound. We then used these extracellular recording techniques in males and female of different ages to quantify the response of the JONs to a brief sound impulse, and also to measure the strength of the connection between the JONs and the GF. At no age was there any significant difference between males and females, for any of the parameters measured. The sensitivity of the JONs to a sound impulse approximately doubled between 1 d and 10 d after eclosion, which corresponds to the period when most mating is taking place. Subsequently JON sensitivity decreased with age, being approximately half as sensitive at 20 d and one-third as sensitive at 50 d, as compared to 10 d. However, the strength of the connection between the auditory input and the GF itself remained unchanged with age, although it did show some variability that could mask any small changes.