Dermoid cyst of the infratemporal fossa: a case report of surgical resection by infratemporal fossa type B approach.

OBJECTIVE: This is a case report of a dermoid cyst located in the infratemporal fossa and its surgical removal using infratemporal fossa type B approach. CASE REPORT: A 15-year-old male was referred from a local clinic after an incidental finding of a mass lesion in the skull base area on computed tomography (CT). Pre-operative magnetic resonance imaging showed a large cystic mass lesion, expanding to the foramen ovale with fat component in the right infratemporal fossa region. The lesion was completely excised using an infratemporal fossa type B approach. CONCLUSION: An extremely rare case of dermoid cysts of the infratemporal fossa was managed with infratemporal fossa type B approach without severe complication.

Normothermia in Patients With Sepsis Who Present to Emergency Departments Is Associated With Low Compliance With Sepsis Bundles and Increased In-Hospital Mortality Rate.

OBJECTIVES: To investigate the impact of normothermia on compliance with sepsis bundles and in-hospital mortality in patients with sepsis who present to emergency departments. DESIGN: Retrospective multicenter observational study. PATIENTS: Nineteen university-affiliated hospitals of the Korean Sepsis Alliance participated in this study. Data were collected regarding patients who visited emergency departments for sepsis during the 1-month period. The patients were divided into three groups based on their body temperature at the time of triage in the emergency department (i.e., hypothermia [< 36°C] vs normothermia [36-38°C] vs hyperthermia [> 38°C]). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Of 64,021 patients who visited emergency departments, 689 with community-acquired sepsis were analyzed (182 hyperthermic, 420 normothermic, and 87 hypothermic patients). The rate of compliance with the total hour-1 bundle was lowest in the normothermia group (6.0% vs 9.3% in hyperthermia vs 13.8% in hypothermia group; p = 0.032), the rate for lactate measurement was lowest in the normothermia group (62.1% vs 73.1% vs 75.9%; p = 0.005), and the blood culture rate was significantly lower in the normothermia than in the hyperthermia group (p < 0.001). The in-hospital mortality rates in the hyperthermia, normothermia, and hypothermia groups were 8.5%, 20.6%, and 30.8%, respectively (p < 0.001), but there was no significant association between compliance with sepsis bundles and in-hospital mortality. However, in a multivariate analysis, compared with hyperthermia, normothermia was significantly associated with an increased in-hospital mortality (odds ratio, 2.472; 95% CI, 1.005-6.080). This association remained significant even after stratifying patients by median lactate level. CONCLUSIONS: Normothermia at emergency department triage was significantly associated with an increased risk of in-hospital mortality and a lower rate of compliance with the sepsis bundle. Despite several limitations, our findings suggest a need for new strategies to improve sepsis outcomes in this group of patients.

The Anti-Inflammatory Role of Bilirubin on "Two-Hit" Sepsis Animal Model.

INTRODUCTION: Bilirubin is a product of the heme catabolism pathway, and it is excreted in bile and removed from the body through the urine. Bilirubin has potent antioxidant properties but also plays a role in anti-inflammation by protecting the body against endotoxin-induced lung inflammation, down-regulating the expression of adhesion molecules, and inhibiting the infiltration of inflammatory cells. Thus, bilirubin is a promising agent that could use in inflammation disease treatment. The application of bilirubin on the "two-hit" sepsis animal model has been, to date, unknown. METHODS: we used lipopolysaccharide to induce initial insults in C57BL/6 mice. After 24 h, mice underwent cecal ligation and puncture to induce the "two-hit" sepsis model. Next, mice were administered 30 mg/kg bilirubin and we observed an improvement. RESULTS: We observed that bilirubin inhibited the expression of pro-inflammatory cytokines, while the levels of anti-inflammatory cytokines were significantly augmented in the lung. Bilirubin improved the survival rate in the sepsis model. Furthermore, we suggest that bilirubin can modulate the accumulation of T-regulatory cells and myeloid-derived suppressor cells. Notably, bilirubin suppressed the activation and functions of T-cells. CONCLUSIONS: These results clarified that bilirubin might improve tissue injury in sepsis through anti-inflammatory mechanisms.

Critical Care In Korea: Present and Future.

Critical (or intensive) care medicine (CCM) is a branch of medicine concerned with the care of patients with potentially reversible life-threatening conditions. Numerous studies have demonstrated that adequate staffing is of crucial importance for patient outcome. Adequate staffing also showed favorable cost-effectiveness in terms of ICU stay, decreased use of resources, and lower re-admission rates. The current status of CCM of our country is not comparable to that of advanced countries. The global pandemic episodes in the past decade showed that our society is not well prepared for severe illnesses or mass casualty. To improve CCM in Korea, reimbursement of the government must be amended such that referral hospitals can hire sufficient number of qualified intensivists and nurses. For the government to address these urgent issues, public awareness of the role of CCM is also required.

Current status of intensive care units registered as critical care subspecialty training hospitals in Korea.

There is a lack of information on critical care in Korea. The aim of this study was to determine the current status of Korean intensive care units (ICUs), focusing on the organization, characteristics of admitted patients, and nurse and physician staffing. Critical care specialists in charge of all 105 critical care specialty training hospitals nationwide completed a questionnaire survey. Among the ICUs, 56.4% were located in or near the capital city. Only 38 ICUs (17.3%) had intensive care specialists with a 5-day work week. The average daytime nurse-to-patient ratio was 1:2.7. Elderly people ≥ 65 yr of age comprised 53% of the adult patients. The most common reasons for admission to adult ICUs were respiratory insufficiency and postoperative management. Nurse and physician staffing was insufficient for the appropriate critical care in many ICUs. Staffing was worse in areas outside the capital city. Much effort, including enhanced reimbursement of critical care costs, must be made to improve the quality of critical care at the national level.

Protective effect of sauchinone against regional myocardial ischemia/reperfusion injury: inhibition of p38 MAPK and JNK death signaling pathways.

Sauchinone has been known to have anti-inflammatory and antioxidant effects. We determined whether sauchinone is beneficial in regional myocardial ischemia/reperfusion (I/R) injury. Rats were subjected to 20 min occlusion of the left anterior descending coronary artery, followed by 2 hr reperfusion. Sauchinone (10 mg/kg) was administered intraperitoneally 30 min before the onset of ischemia. The infarct size was measured 2 hr after resuming the perfusion. The expression of cell death kinases (p38 and JNK) and reperfusion injury salvage kinases (phosphatidylinositol-3-OH kinases-Akt, extra-cellular signal-regulated kinases [ERK1/2])/glycogen synthase kinase (GSK)-3ß was determined 5 min after resuming the perfusion. Sauchinone significantly reduced the infarct size (29.0% ± 5.3% in the sauchinone group vs 44.4% ± 6.1% in the control, P < 0.05). Accordingly, the phosphorylation of JNK and p38 was significantly attenuated, while that of ERK1/2, Akt and GSK-3ß was not affected. It is suggested that sauchinone protects against regional myocardial I/R injury through inhibition of phosphorylation of p38 and JNK death signaling pathways.

Importance of High-Frequency Vestibular Function in the Prognosis of Bilateral Vestibulopathy.

OBJECTIVES: The aim of this study was to investigate whether preserved vestibular function in the high-frequency range influences the prognosis of patients with bilateral vestibulopathy (BVP) after vestibular rehabilitation. METHODS: Twenty-four patients followed up with vestibular rehabilitation were recruited. The enrolled patients were divided into two groups according to the preservation of the high-frequency vestibulo-ocular reflex (VOR) based on the video head impulse test (vHIT). The results of computerized dynamic posturography and the Dizziness Handicap Inventory (DHI) survey collected at baseline and at the 6-month follow-up after vestibular rehabilitation therapy were analyzed. RESULTS: Both groups showed significantly increased composite and DHI scores after follow-up with vestibular rehabilitation. The group with preserved high-frequency VOR showed a better composite score (p=0.064) and vestibular score (p= 0.008) than the group with lost high-frequency VOR at the 6-month follow up. The DHI score significantly decreased only in the group with lost high-frequency VOR (p=0.047). Among the three vestibular function tests (caloric test, rotary chair test, and vHIT) used to diagnose BVP, only vHIT showed a significant correlation (p=0.015) with a favorable prognosis (composite score ≥70). CONCLUSION: Better treatment outcomes are likely in patients with BVP with preserved vestibular function in response to high-frequency stimulation, as measured by the vHIT.

Supplementary Effect of Choline Alfoscerate on Speech Recognition in Patients With Age-Related Hearing Loss: A Prospective Study in 34 Patients (57 Ears).

To investigate the effect of choline alfoscerate (CA) on hearing amplification in patients with age related hearing loss, we performed a prospective case-control observational study from March 2016 to September 2020. We assessed patients with bilateral word recognition score (WRS) <50% using monosyllabic words. The patients were 65-85 years old, without any history of dementia, Alzheimer's disease, parkinsonism, or depression. After enrollment, all patients started using hearing aids (HA). The CA group received a daily dose of 800 mg CA for 11 months. We performed between-group comparisons of audiological data, including pure tone audiometry, WRS, HA fitting data obtained using real-ear measurement (REM), and the Abbreviated Profile of Hearing Aid benefit scores after treatment. After CA administration, the WRS improved significantly in the CA group (4.2 ± 8.3%), but deteriorated in the control group (-0.6 ± 8.1%, p = 0.035). However, there was no significant between-group difference in the change in pure tone thresholds and aided speech intelligibility index calculated from REM. These findings suggest that the difference in WRS was relevant to central speech understanding rather than peripheral audibility. Therefore, administering oral CA could effectively enrich listening comprehension in older HA users.

Neutrophils infiltrate into the spiral ligament but not the stria vascularis in the cochlea during lipopolysaccharide-induced inflammation.

It has been challenging to apply intravital imaging for monitoring the inner ear, as the anatomical location and intricate structure hamper the access of imaging instruments to the inner ear of live mice. By employing intravital imaging of the cochlea in live mice with two-photon microscopy, we investigated neutrophil infiltration into the cochlea tissue and its characteristics under a lipopolysaccharide (LPS)-induced inflammatory state. Methods: Cochlea inflammation was induced by LPS injection to the middle ear. Using two-photon intravital microscopy with specifically designed surgical exteriorization of the cochlea in live mice, we investigated the dynamic features of neutrophils in the lateral wall of the cochlea. The molecular expression pattern of the cochlea lateral wall was also investigated during the LPS-induce inflammation. Results: Despite the contention of whether neutrophils are recruited to the spiral ligament (SL) during inflammation, we observed that LPS-induced inflammation of the middle ear, which mimics acute otitis media, triggered neutrophil migration to the SL in the lateral wall. Notably, massive neutrophil infiltration to the SL occurred 2 days after LPS inoculation, but there was no neutrophil infiltration into the stria vascularis (SV) region. At 1 day after LPS-induced cochlear inflammation, increased mRNA expression of interleukin-1ß, interleukin-6 were identified in both the SL and SV, while the ICAM-1 mRNA expression increased only in the SL. The differential reactivity of ICAM-1 is likely responsible for the different neutrophil recruitment pattern in the cochlea. Conclusion: Intravital imaging of the cochlea revealed that neutrophil recruitment and infiltration during inflammation are spatially controlled and exclusively observed in the SL but not in the SV and organ of Corti.

Corrigendum: Supplementary Effect of Choline Alfoscerate on Speech Recognition in Patients With Age-Related Hearing Loss: A Prospective Study in 34 Patients (57 Ears).

[This corrects the article DOI: 10.3389/fnagi.2021.684519.].

Three-Dimensional Distribution of Cochlear Macrophages in the Lateral Wall of Cleared Cochlea.

OBJECTIVES: Resident macrophages are well known to be present in the cochlea, but the exact patterns thereof in spiral ligaments have not been discussed in previous studies. We sought to document the distribution of macrophages in intact cochleae using three-dimensional imaging. METHODS: Cochleae were obtained from C-X3-C motif chemokine receptor 1+/GFP mice, and organ clearing was performed. Three-dimensional images of cleared intact cochleae were reconstructed using two-photon microscopy. The locations of individual macrophages were investigated using 100-µm stacked images to reduce bias. Cochlear inflammation was then induced by lipopolysaccharide (LPS) inoculation into the middle ear through the tympanic membrane. Four days after inoculation, three-dimensional images were obtained. RESULTS: Macrophages were scarce in areas adjacent to the stria vascularis, particularly the area just beneath it even though many have suspected macrophages to be abundant in this area. This finding remained consistent upon LPS-induced cochlear inflammation, despite a significant increase in the number of macrophages, compared to non-treated cochlea. CONCLUSION: Resident macrophages in spiral ligaments are scarce in areas adjacent to the stria vascularis.

Relationship between Hearing Loss and Dementia Differs According to the Underlying Mechanism.

BACKGROUND AND PURPOSE: The associations between hearing loss (HL) and the mechanisms underlying cognitive impairment (CI) remain unclear. We evaluated the effects of clinical factors, vascular magnetic resonance imaging (MRI) markers, and CI mechanisms on HL. METHODS: In total, 112 patients with CI (59% demented) and subjective HL prospectively underwent MRI, amyloid positron-emission tomography (PET), hearing evaluations, and neuropsychological tests including a language comprehension test. Patients were categorized into pure-Alzheimer's disease-related CI (ADCI), pure-Lewy-body disease-related CI (LBCI), mixed-ADCI/LBCI, and non-ADCI/LBCI groups based on clinical features and PET biomarkers. RESULTS: The risk of peripheral HL [defined as a pure-tone average (PTA) threshold >40 dB] was higher in the pure-LBCI group than in the pure-ADCI and mixed-ADCI/LBCI groups, and lower in the presence of ADCI. The non-ADCI/LBCI group had the most-severe vascular MRI markers and showed a higher risk of peripheral HL than did the pure-ADCI and mixed-ADCI/LBCI groups. While the pure-LBCI group had a higher risk of comprehension dysfunction than the pure-ADCI group regardless of the PTA and the score on the Korean version of the Mini Mental State Examination (K-MMSE), those in the pure-LBCI group even with a better K-MMSE score had a risk of comprehension dysfunction comparable to that in the mixed-ADCI/LBCI group due to a worse PTA. CONCLUSIONS: Peripheral HL could be associated with the absence of significant ß-amyloid deposition in patients with CI and characteristic of the pure-LBCI and non-ADCI/LBCI groups.

Protective role of curcumin against lipopolysaccharide-induced inflammation and apoptosis in human neutrophil.

BACKGROUND: Sepsis, an uncontrolled host response to infection, may be life-threatening organ injury. Neutrophils play a critical role in regulation of host immune response to infection. Curcumin, known as a spice and food coloring agent, possesses anti-inflammatory properties. In this study, we investigated the effects of curcumin on lipopolysaccharide (LPS)-induced neutrophil activation with its signaling pathways. METHODS: Isolated human neutrophils were incubated without or with LPS and curcumin, and the expression of pro-inflammatory cytokines, such as tumor necrosis factor alpha (TNF-α), interleukin (IL)-6, and IL-8 were assessed by enzyme-linked immunosorbent assays. The expression of mitogen-activated protein kinases such as p38, extracellularsignal-regulated kinase (ERK)1/2, and c-Jun N-terminal kinase (JNK) were evaluated by Western blot analysis. Neutrophil apoptosis was also measured by fluorescence-activated cell sorting (annexin V/propidium iodide) in LPS-stimulated neutrophils under treatment with curcumin. RESULTS: Curcumin attenuated expression of TNF-α, IL-6, and IL-8 and the phosphorylation levels of p38 and JNK, but not ERK1/2, in LPS-stimulated neutrophils. Additionally, curcumin restored the delayed neutrophil apoptosis by LPS-stimulated neutrophils(19.7 ± 3.2 to 38.2 ± 0.5%, P < 0.05). CONCLUSIONS: Our results reveal the underlying mechanism of how curcumin attenuate neutrophil activation and suggest potential clinic applications of curcumin supplementation for patients with severe sepsis and septic shock. Additional clinical studies are required to confirm these in vitro findings.

Synergistic effect of smoking on age-related hearing loss in patients with diabetes.

This study investigated the synergistic effects of risk factors on age-related hearing loss (ARHL) using nationwide cross-sectional data of 33,552 individuals from the 2010‒2013 Korea National Health and Nutrition Examination Survey. Patients with ARHL were selected based on their pure-tone audiometry results. Previously reported risk factors for ARHL were analyzed using logistic regression and propensity score-matching, and synergistic effects between risk factors were analyzed using propensity score-matching. Of the 12,570 individuals aged 40-79 years, 2002 (15.9%) met the criteria for ARHL. Male sex, exposure to occupational noise, and diabetes showed a significant relationship with ARHL (p < 0.05) in both the logistic regression and propensity score-matching analyses. Smoking and diabetes showed the strongest significant synergistic effect on ARHL (odds ratio [OR] 1.963, 95% confidence interval [CI] 1.285‒2.998; p = 0.002). In the subgroup analysis based on smoking status, current smokers with diabetes had a significant relationship with ARHL (OR 1.883, CI 1.191‒2.975; p = 0.009), whereas ex-smokers with diabetes did not (OR 1.250; CI 0.880‒1.775; p = 0.246). This implies that current smokers with diabetes may benefit from the cessation of smoking. In conclusion, patients with diabetes should strictly avoid or cease smoking to prevent the progression of ARHL.

Audiological and Vestibular Functions in Patients With Lateral Semicircular Canal Dysplasia and Aplasia.

OBJECTIVES: The aim of the present study was to evaluate audiologic and vestibular functions in patients with lateral semicircular canal (LSCC) dysplasia/aplasia. METHODS: We conducted a retrospective study of a patients with LSCC dysplasia and aplasia at tertiary referral center. The subjects included 15 patients with LSCC dysplasia or aplasia, with or without combined inner ear anomalies. Medical history, temporal bone computed tomography scans, pure-tone audiograms, and vestibular function test results were analyzed. RESULTS: LSCC anomaly was identified in 15 patients (20 ears). Nine patients had unilateral LSCC dysplasia only and showed a mean pure-tone average of 45.5±28.7 dB, while three patients (33.3%) among them had normal hearing. Six patients had bilateral LSCC dysplasia/aplasia combined with other inner ear anomalies and profound bilateral hearing loss. Notably, only four out of 15 patients (26.7%) had dizziness symptoms. On caloric test, patients with isolated LSCC dysplasia showed a 51.8%±29.3% level of canal paresis (eight out of nine patients showed anomalies), whereas patients with bilateral LSCC dysplasia/aplasia presented bilateral vestibular loss. One patient with isolated LSCC underwent video-head impulse test; horizontal canal gain decreased to 0.62 (17% asymmetry) and anterior canal gain was 0.45 (52.6% asymmetry), whereas posterior canal gain was normal. CONCLUSION: Bilateral LSCC dysplasia/aplasia is comorbid with other inner ear anomalies and presents as profound bilateral hearing loss and vestibulopathy. In contrast, isolated unilateral LSCC dysplasia presents as ipsilateral horizontal canal paresis. Hearing function in isolated LSCC dysplasia is usually, but not always, impaired with varying severity.

Clinical features and treatment of endolymphatic sac tumor.

Background: Endolymphatic sac tumor (ELST) is an extremely rare disease that does not have established clinical guidelines.Objective: To provide guidance for the diagnosis and management of ELSTs.Methods: We retrospectively reviewed the medical records of patients who were suspected to have a lesion in the location of endolymphatic sac. Seven patients were included. Histopathologic diagnosis confirmed five ELSTs and two other diseases.Results: All of the enrolled patients had hearing impairment. Facial palsy was found in four out of five patients with ELST, whereas none of the patients in other disease group showed facial palsy. CT and MRI findings were consistent with those in previous literatures; however, angiographic findings were not consistent with those previously reported. All patients underwent surgery. Recurrence occurred in two patients with ELST, although there was no visible remnant tumor after the operation. These patients were treated with stereotactic radiosurgery.Conclusion: Hearing impairment and facial palsy were representative symptoms of ELST. All ELSTs showed 'salt and pepper' signal in MRI T1-weighted images, and smaller tumors could have blood supply from AICA in the radiologic study. Complete surgical resection with optional stereotactic radiosurgery should be considered in ELST.HighlightsHearing impairment and facial weakness are remarkable symptoms of ELST compared to other diseases that invade the endolymphatic sac.All ELSTs showed 'salt and pepper' signal in MRI T1-weighted images.ELST less than 3 cm in diameter could have blood supply from AICA.A complete surgical excision with optional stereotactic radiosurgery is required.

Investigation of intact mouse cochleae using two-photon laser scanning microscopy.

OBJECTIVES: The investigation of cochlear hair cells and lateral wall is a time-consuming and labor-intensive process. However, it is a mandatory experiment in audiology research. Here we suggest a novel method for investigating the inner ear microstructures from intact cochleae using two-photon laser scanning microscopy (TPLSM). This technique guarantees fewer artifacts and technical simplicity. METHODS: Using TPLSM, we investigated the whole mount cochleae, decalcified cochleae, and cleared cochleae of wild type C57BL/6 mice. CX3CR1+/GFP mice were used to investigate the feasibility of visualizing cellular structures in the cochlear spiral ligament. All samples were investigated without staining. RESULTS: Endogenous fluorescence emission from the outer hair cells was strong enough to be distinguished from the other structures in all samples. From the single apical view, 50 and 90% of the whole hair cells of the decalcified cochleae and cleared cochleae, respectively, could be visualized without staining using TPLSM. Capillary structure of stria vascularis and spiral ligament could be visualized by endogenous fluorescence without staining. CONCLUSION: We successfully investigated the hair cells and lateral wall of mouse cochleae using TPLSM without using staining or any destructive procedures. This method is easier, faster, and more reliable than conventional methods.

Clinical Experience of Vibroplasty With Direct Coupling to the Oval Window Without Use of a Coupler.

OBJECTIVES/HYPOTHESIS: To investigate the efficacy of direct implantation of a Vibrant Soundbridge (VSB) implant in the oval window (OW) without the use of an OW coupler in patients with severe mixed hearing loss. STUDY DESIGN: Retrospective chart review METHODS: A total of 62 patients underwent VSB implantation between July 2016 and December 2018 at Severance Hospital in Seoul, South Korea. Among them, eight patients (nine ears) with moderate-to-severe mixed hearing loss were implanted with a VSB directly in the OW. A floating mass transducer (FMT) was attached to the stapes footplate and covered with tragal cartilage. The outcomes were evaluated using pure-tone audiogram and speech audiogram preoperatively and postoperatively. Word recognition score (WRS; % correct) were measured at the most comfortable loudness (MCL) level to evaluate speech perception. RESULTS: All cases posed difficulty with round window vibroplasty during surgery, and eventually, an FMT was appropriately placed in the OW without a coupler. Preoperative and postoperative bone conduction thresholds were not different. VSB-aided threshold improved in terms of functional and effective gains. Interestingly, four cases showed improved air conduction thresholds without the use of a VSB. In addition, MCL level with a VSB was significantly lower than that with a hearing aid, and VSB-aided WRS improved over time. CONCLUSIONS: Direct implantation of a VSB in the OW without the use of a coupler showed favorable hearing outcomes, and the OW vibroplasty was safe. Direct OW vibroplasty without a coupler is a reliable procedure and can be a good option for hearing rehabilitation in patients with severe mixed hearing loss. LEVEL OF EVIDENCE: 4 Laryngoscope, 2020.

Effect of BMS-470539 on lipopolysaccharide-induced neutrophil activation.

BACKGROUND: BMS-470539, a recently introduced selective agonist of the melanocortin 1 receptor, is known to have anti-inflammatory properties. In this study, we investigated the effects of BMS-470539 on lipopolysaccharide (LPS)-induced inflammatory responses and delayed apoptosis with its signaling pathways in human neutrophils. METHODS: Isolated human neutrophils were incubated with various concentrations of BMS-470539 (1, 10, and 100 µM) in the presence or absence of LPS (100 ng/ml), and the expression of pro-inflammatory cytokines, such as tumor necrosis factor alpha, interleukin (IL)-6, and IL-1ß, were assessed. The effects of BMS-470539 on the expression of mitogen-activated protein kinases (MAPKs), such as p38, extracellular-signal-regulated kinase 1/2, and c-Jun N-terminal kinase, and the expression of nuclear factor kappa B (NF-κB) in LPS-stimulated human neutrophils, were evaluated by enzyme-linked immunosorbent assay. Neutrophil apoptosis was also measured by fluorescence-activated cell sorting (annexin V/propidium iodide) in LPS-stimulated neutrophils under treatment with BMS-470539. RESULTS: BMS-470539 attenuated LPS-induced expression of pro-inflammatory cytokines, and phosphorylation of MAPKs and NF-κB. LPS stimulation reduced neutrophil apoptosis compared to the controls; however, BMS-470539 significantly inhibited the reduction of neutrophil apoptosis. CONCLUSIONS: BMS-470539 can suppress the inflammatory responses of LPS-stimulated neutrophils by inhibition of MAPK pathways or NF-κB pathway, and it can also inhibit LPS-delayed neutrophil apoptosis.

Effect of Specific Retinoic Acid Receptor Agonists on Noise-Induced Hearing Loss.

Noise is one of the most common causes of hearing loss in industrial countries. There are many studies about chemical agents to prevent noise-induced hearing loss (NIHL). However, there is no commercially available drug yet. Retinoic acid is an active metabolite of Vitamin A; it has an anti-apoptic role in NIHL. This study aims to verify the differences among selective agonists of retinoic acid receptors (RARs) in NIHL. All-trans retinoic acid (ATRA), AM80 (selective retinoic acid receptor α agonist), AC261066 (Selective retinoic acid receptor ß1 agonist), and CD1530 (Selective retinoic acid λ agonist) were injected to 6-7 weeks old CJ5BL/6 mice before noise (110 dB for 3 h) exposure. In the auditory brainstem response test pre-, post 1, 3, and 7 days after noise exposure, not only ATRA but all kinds of selective RAR agonists showed protective effects in hearing threshold and wave I amplitude. Though there was no significant difference in the level of protective effects between agonists, α agonist showed the most prominent effect in preserving hearing function as well as outer hair cells after noise exposure. In conclusion, selective agonists of RAR demonstrate comparable protective effects against NIHL to retinoic acid. Given that these selective RAR agonists have less side effects than retinoic acid, they may be promising potential drugs against NIHL.