Association between Hyperuricemia and Hearing Impairment: Results from the Korean National Health and Nutrition Examination Survey.

Background and Objectives: Hyperuricemia is associated with a variety of comorbidities. The objective of this study was to investigate the association between hyperuricemia and hearing impairment in Korean adults. Materials and Methods: Audiometric and laboratory test data from the 2019 to 2020 Korean National Health and Nutrition Examination Survey (KNHANES) were used for analysis. Hearing impairment was defined as a pure-tone average (0.5, 1, 2, 4 kHz) threshold level ≥ 41 decibels. The definition of hyperuricemia was different for males and females: >7 mg/dL for males vs. >6 mg/dL for females. Results: A total of 4857 (weight n = 17,990,725) subjects were analyzed. The mean age was 56.8 years old. The weighted prevalence was 12.1% for hyperuricemia and 2.5% for gout. The prevalence of hearing impairment was 13.4%. In the univariable analysis, hyperuricemia was significantly associated with hearing impairment. However, the diagnosis of gout was not associated with hearing impairment. In the multivariable analysis, hyperuricemia (odds ratios (OR): 1.41, 95% confidence interval [CI]: 1.03-1.92, p = 0.030) was associated with hearing impairment along with age (OR: 1.12, 95% CI: 1.10-1.14, p < 0.001), female sex (OR: 0.43, 95% CI: 0.34-0.64, p < 0.001), education (OR: 0.43, 95% CI: 0.30-0.63, p = 0.001), and occupational noise exposure (OR: 1.67, 95% CI: 1.25-2.22, p = 0.001). In the subgroup analysis, hyperuricemia was associated with hearing impairment in females (OR: 1.59, 95% CI: 1.02-2.48, p = 0.041) and the elderly aged 60 years or more (OR: 1.45, 95% CI: 1.05-1.99, p = 0.023). Conclusions: Hyperuricemia was independently associated with hearing impairment, especially in females and the elderly aged 60 years or more.

A Case of Diffuse Thyroid Hematoma after Ultrasound-Guided Fine Needle Aspiration.

Ultrasound-guided fine needle aspiration is an easy, safe, and efficient method of diagnosing thyroid diseases. Recent guidelines and studies have demonstrated that this test has a low incidence of complications; thus, most guidelines do not provide recommendations for post-exam care. However, the risk of serious and fatal bleeding in selected patients with bleeding tendency exists. Although screening tests for coagulation are not always necessary, a thorough assessment of past medical history needs to be made to identify disorders affecting coagulation function and bleeding risk factors, such as the use of antithrombotic drugs. This is a case report of a 70-year-old female patient who continued to take edoxaban and suffered bilateral thyroid hematoma a few hours after ultrasound-guided thyroid fine needle aspiration. The patient successfully recovered after undergoing conservative treatment.

Predicting the Cochlear Dead Regions Using a Machine Learning-Based Approach with Oversampling Techniques.

Background and Objectives: Determining the presence or absence of cochlear dead regions (DRs) is essential in clinical practice. This study proposes a machine learning (ML)-based model that applies oversampling techniques for predicting DRs in patients. Materials and Methods: We used recursive partitioning and regression for classification tree (CT) and logistic regression (LR) as prediction models. To overcome the imbalanced nature of the dataset, oversampling techniques to duplicate examples in the minority class or to synthesize new examples from existing examples in the minority class were adopted, namely the synthetic minority oversampling technique (SMOTE). Results: The accuracy results of the 10-fold cross-validation of the LR and CT with the original data were 0.82 (±0.02) and 0.93 (±0.01), respectively. The accuracy results of the 10-fold cross-validation of the LR and CT with the oversampled data were 0.66 (±0.02) and 0.86 (±0.01), respectively. Conclusions: This study is the first to adopt the SMOTE method to assess the role of oversampling methods on audiological datasets and to develop an ML-based model. Considering that the SMOTE method did not improve the model's performance, a more flexible model or more clinical features may be needed.

Results of anterior facial nerve rerouting procedures for removing skull base tumors.

OBJECTIVES: The purpose of this study was to estimate the rates of functional recovery of the facial nerve and of total tumor resection in patients who undergo short anterior rerouting and long anterior rerouting of the facial nerve in removal of skull base tumors. METHODS: We retrospectively collected data on 37 patients with skull base tumors who underwent facial nerve rerouting during the procedure for tumor removal. Information on the rerouting technique, the completeness of tumor resection, and changes in facial nerve function were obtained from the medical records. Rerouting techniques were classified as short anterior rerouting or long anterior rerouting. RESULTS: Ten of 16 patients (62.5%) in the group with short anterior rerouting showed postoperative facial palsy, and all completely recovered within 1 year. In the group with long anterior rerouting, 18 of 21 patients (85.7%) showed postoperative facial palsy, and recovery to a preoperative level of facial function was found in 10 patients at 1 year of follow-up. Total tumor resection was possible in 94% and 81% of patients with short rerouting and long rerouting, respectively. The mean operation time was not significantly related to the postoperative recovery of facial function. CONCLUSIONS: Short rerouting techniques, when appropriately chosen on the basis of tumor and patient characteristics, offer excellent preservation of facial function and tumor resection, comparable to those of long rerouting techniques.

Does Cognitive Function Affect Performance and Listening Effort During Bilateral Wireless Streaming in Hearing Aid Users?

Background and Objectives: : Wireless streaming technology (WT), designed to transmit sounds directly from a mobile phone to hearing aids, was developed to enhance the signal-to-noise ratio. However, the advantages of WT during phone use and the specific demographic that can fully benefit from this technology has not been thoroughly evaluated. We aimed to investigate the benefits and identify predictive factors associated with bilateral wireless streaming among hearing aid users. Subjects and Methods: : Eighteen adults with symmetrical, bilateral hearing loss participated in the study. To assess the benefits of wireless streaming during phone use, researchers assessed sentence/word recognition and listening effort in two scenarios: a noisy background with WT turned "OFF" or "ON." Listening effort was evaluated through self-reported measurements. Cognitive function was also assessed using the Montreal Cognitive Assessment (MoCA) score. Results: : Participant mean age was 57.3 years (range 27-70), and the mean MoCA score was 27.0 (23-30). The activation of WT demonstrated a significant improvement in the sentence/word recognition test and reduced listening effort. The MoCA score showed a significant correlation with WT (ρ=0.59, p=0.01), suggesting a positive association between cognitive function and the benefits of WT. Conclusions: : Bilateral wireless streaming may enhance sentence/word recognition and reduce listening effort during phone use in hearing aid users, with these benefits potentially linked to cognitive function.

A Case of Massive Subcutaneous Emphysema and Pneumomediastinum Due to Dehiscence of Stoma After Emergent Tracheostomy.

Tracheostomy is commonly performed on patients who require long-term ventilator support. As with all other airway managements, tracheostomy comes with risks: tracheal scarring, tracheal rupture, pneumothorax, and tracheoesophageal fistula. Although rare, free air leakage into the surrounding tissues of the tracheostomy site and consequent pneumomediastinum can also occur due to various reasons, such as tracheal rupture and mispositioning of the tracheal tube. Such conditions may require treatments including high flow oxygen, ventilator management, and occasionally surgical intervention. In our case of a 61-year-old female, emergent tracheostomy was performed and subsequent complications of massive pneumomediastinum and subcutaneous emphysema were treated with negative pressure wound therapy. The follow-up radiograph after negative pressure wound therapy showed resolution of pneumomediastinum and subcutaneous emphysema, and there were no additional complications. Negative pressure wound therapy is an effective treatment option for massive pneumomediastinum and subcutaneous emphysema after tracheostomy.

Electrophysiological Changes Associated with the Progression of Noise-Induced Hearing Loss.

BACKGROUND: The aim of this study is to evaluate the clinical characteristics and electrophysiological changes in patients with different degrees of noise-induced hearing loss compared with those of normal controls to elucidate the progression of auditory neural damage attributed to noise exposure. METHODS: A retrospective cohort study was conducted through a review of the medical records for the patients who presented to a tertiary referral center. Sixty-nine participants were included in the study: 29 had noise-induced hearing loss, and 40 were healthy controls. All the participants underwent electrophysiological tests and pure-tone audiometry. RESULTS: Nine patients showed mild hearing loss (mild hearing loss group), while the others showed worse than moderate hearing loss on puretone audiometry (severe hearing loss group). Significantly reduced wave I and V amplitudes of auditory brainstem response were present in both mild and severe hearing loss groups compared to the control group (P -lt; .001 and P=.002, respectively), without significant differences between the mild and severe hearing loss groups. In the multivariate analysis, auditory brainstem response wave V amplitude was negatively associated with auditory brainstem response wave I-V inter-peak latency delay (B=-0.48, P=.02). CONCLUSION: The results of the present study confirm the similarity in the electrophysiological characteristics between the mild and severe hearing loss groups. Thus, widespread disruption in the auditory neural conduction could have been established in the early period when the patient developed mild hearing loss following noise exposure.

Improved Prediction of Hearing Loss after Temporal Bone Fracture by Applying a Detailed Classification for Otic Capsule-Violating Fracture: A Wide Scope Analysis with Large Case Series.

INTRODUCTION: This study aimed to analyze the predictability of temporal bone (TB) fracture-associated hearing loss by applying a detailed classification separating individual injury of the cochlea, vestibule, and semicircular canals (SCC). METHODS: In this retrospective study, patients with otic capsule-violating (OCV) fractures were further classified as OCV-C(VS) when the cochlea was involved regardless of vestibule or SCC involvement, OCV-V(S) when the vestibule was involved regardless of SCC involvement, and OCV-S when the fracture only involved SCC. Hearing changes were compared by applying the above-mentioned classification, and TB fracture-induced facial palsy was also analyzed. RESULTS: A total of 119 patients were included. Patients with OCV fractures had significantly worse bone conduction (BC) and air conduction (AC) thresholds (59.1 ± 25.3 and 87.0 ± 29.5 dB) than those with otic capsule-sparing (OCS) fractures (20.1 ± 17.9 and 36.5 ± 21.9 dB; p < 0.001 for each comparison). The BC and the AC thresholds of OCV-C(VS) (77.5 ± 11.0 and 114.2 ± 14.3 dB) and OCV-V(S) (69.3 ± 27.7 and 98.0 ± 22.2 dB) were significantly higher than OCV-S (40.1 ± 22.9 and 62.1 ± 25.6 dB; p < 0.001 for each comparison). The BC hearing thresholds were not significantly improved in the last pure tone audiometry when compared for total, OCV, or OCS cases. The AC threshold significantly improved in OCS cases. In a considerable number of cases with facial palsy, causative fracture lines involved the geniculate ganglion or tympanic segment without the involvement of the otic capsule. Most cases showed significant improvement; however, recovery was limited in cases with obvious fallopian canal disruption. CONCLUSIONS: The cases with sole involvement of SCC had significantly better hearing thresholds than those with cochlear or vestibule involvement, even in OCV fracture cases.

Impact of changes in protective behaviors and out-of-household activities by age on COVID-19 transmission and hospitalization in Chicago, Illinois.

PURPOSE: Even with an efficacious vaccine, protective behaviors (social distancing, masking) are essential for preventing COVID-19 transmission and could become even more important if current or future variants evade immunity from vaccines or prior infection. METHODS: We created an agent-based model representing the Chicago population and conducted experiments to determine the effects of varying adult out-of-household activities (OOHA), school reopening, and protective behaviors across age groups on COVID-19 transmission and hospitalizations. RESULTS: From September-November 2020, decreasing adult protective behaviors and increasing adult OOHA both substantially impacted COVID-19 outcomes; school reopening had relatively little impact when adult protective behaviors and OOHA were maintained. As of November 1, 2020, a 50% reduction in young adult (age 18-40) protective behaviors resulted in increased latent infection prevalence per 100,000 from 15.93 (IQR 6.18, 36.23) to 40.06 (IQR 14.65, 85.21) and 19.87 (IQR 6.83, 46.83) to 47.74 (IQR 18.89, 118.77) with 15% and 45% school reopening. Increasing adult (age ≥18) OOHA from 65% to 80% of prepandemic levels resulted in increased latent infection prevalence per 100,000 from 35.18 (IQR 13.59, 75.00) to 69.84 (IQR 33.27, 145.89) and 38.17 (IQR 15.84, 91.16) to 80.02 (IQR 30.91, 186.63) with 15% and 45% school reopening. Similar patterns were observed for hospitalizations. CONCLUSIONS: In areas without widespread vaccination coverage, interventions to maintain adherence to protective behaviors, particularly among younger adults and in out-of-household settings, remain a priority for preventing COVID-19 transmission.

Unilateral sudden sensorineural hearing loss with vertigo as a first symptom of bilateral internal auditory canal metastases: a case report.

There have been relatively few reports of bilateral internal auditory canal metastases of asymptomatic primary pulmonary adenocarcinoma presenting as unilateral sudden sensorineural hearing loss and vertigo. We report a case of a 60-year-old male patient who complained of sudden hearing loss in the right ear and vertigo. Upon a physical examination, no definite neurological signs or nystagmus were observed. Pure-tone audiometry showed deafness in the right ear at all frequencies and high-frequency sensorineural hearing loss in the left ear. The video head impulse test suggested bilateral vestibulopathy. Magnetic resonance imaging of the brain (with gadolinium contrast) revealed bilateral internal auditory canal enhancement and a variable-sized nodular and peripheral-enhancing lesion in the cerebrum and the right cerebellum. A computed tomographic and bronchoscopic biopsy identified asymptomatic primary pulmonary adenocarcinoma in the left upper lobe of the lungs. This is a rare report of bilateral internal auditory canal metastases in an asymptomatic patient with primary pulmonary adenocarcinoma who initially presented with symptoms of unilateral sudden sensorineural hearing loss with vertigo.

Analysis of Auditory Brainstem Response Change, according to Tinnitus Duration, in Patients with Tinnitus with Normal Hearing.

OBJECTIVES: The purpose of this study was to analyze auditory brainstem response (ABR) waveforms of patients with tinnitus with normal hearing, according to tinnitus duration, and demonstrate the possible pathophysiological mechanisms of tinnitus. MATERIALS AND METHODS: From January 2016 to December 2017, patients who presented to our hospital with tinnitus as their chief complaint were enrolled and reviewed retrospectively. Pure tone audiometry and ABR tests were performed. The patients were classified into three groups according to tinnitus duration: acute (<1 month), subacute (1-6 months), and chronic (>6 months). The amplitudes of waves I and V and the latencies of waves I, III, and V were evaluated. In this study, 177 ears of 128 patients with tinnitus with normal hearing were evaluated. RESULTS: Wave V amplitude was significantly lower during the subacute phase than during the acute phase. The absolute latency value of wave V was greater during the subacute phase than during the acute phase. The interpeak latency I-V was significantly prolonged during the subacute phase compared with the acute and chronic phases. Wave V amplitude, wave V absolute latency, and interpeak latency I-V varied significantly between cases with a 1-month and 6-month tinnitus history. CONCLUSION: The compensatory response to tinnitus decreased sharply after 1 month of symptoms. Early tinnitus identification and treatment initiation are recommended.

Association between the severity of hearing loss and the risk of dementia within the 2010-2017 national insurance service survey in South Korea.

Hearing loss and dementia are highly prevalent neurologic conditions in older adults that can considerably impact the quality of life and create social and familial burdens. To investigate the impact of hearing loss on the risk of developing dementia in a nationwide long-term follow-up study using data obtained from the South Korean National Health Information Database. Retrospective medical data for patients of all ages were extracted from the database between January 2010 and December 2017. According to the national disability registry, the degree of severe-profound hearing loss is classified into six grades. We categorized hearing loss into three groups based on the disability registry severity: (1) severe hearing disability (HD), defined as 1st to 3rd grade disabling hearing loss; (2) non-severe HD, 4th and 5th grade disabling hearing loss; and (3) ipsilateral HD, 6th grade disabling hearing loss. After adjusting for potential confounding variables, the hazard ratio (HR) for all dementia types was 1.336 (95% CI 1.306-1.367) in the severe HD group, 1.312 (95% CI 1.286-1.338) in the non-severe HD group, and 1.257 (95% CI 1.217-1.299) in the ipsilateral HD group. On assessing by the age group, the risk of all dementia types in patients younger than 65 years was as follows: HR 1.933 (95% CI 1.779-2.101), 1.880 (95% CI 1.732-2.041), and 1.601 (95% CI 1.435-1.787) in the severe, non-severe, and ipsilateral HD groups, respectively. This study demonstrates that the impact of hearing loss on dementia incidence is severity-dependent, and the risk increases in patients younger than 65 years of age.

(18)F-Labeled benzylideneaniline derivatives as new ligands for beta-amyloid plaque imaging in Alzheimer's disease.

INTRODUCTION: Noninvasive early detection of beta-amyloid (Abeta) plaques might be useful for the treatment of patients with Alzheimer's disease (AD). We herein describe the synthesis of (18)F-labeled benzylideneaniline derivatives using a novel labeling approach for imaging Abeta plaques in AD patients. METHODS: Benzylidenaniline derivatives were synthesized by reacting fluorobenzaldehyde and corresponding aniline derivatives. Fluorobenzaldehyde was labeled with (18)F by incubating [(18)F]fluoride with N,N,N-trimethylbenzaldehyde in the presence of tetrabutylammonium bicarbonate. In vitro binding assay, stability test and biodistribution study were performed. RESULTS: These compounds were stable at alkaline pH (pH >9); however, they were hydrolyzed rapidly at physiological pH (pH approximately 7.4). The K(i) values of amine-containing benzylideneaniline derivatives for Abeta(1-40) and Abeta(1-42) aggregates were 26-78 nM. These (18)F-labeled benzylideneaniline derivatives showed high brain uptake and rapid clearance after intravenous administration in normal mice (1.8-3.1%ID/g at 2 min and 0.1-1.2%ID/g at 30 min). The low level of bone activity at 30 min indicated that these (18)F-labeled benzylideneanilines are not prone to defluorination. Furthermore, the compounds have suitable lipophilicity - a property required to penetrate the blood-brain barrier. CONCLUSION: These results showed that the instability of these compounds could cause a higher early phase/late phase ratio due to rapid clearance in the normal brain. The findings from this study suggest that these (18)F-labeled benzylideneaniline derivatives are feasible for the imaging of Abeta plaques.

Normative wideband absorbance measures in healthy neonates in Korea: A preliminary study.

INTRODUCTION: The usefulness of wideband absorbance (WBA) in newborns is well-demonstrated. However, it is still not clear whether there might be a difference according to ethnicity with respect to ambient WBA; therefore, further investigation is necessary to evaluate ethnic-specific normative WBA values in newborns. METHODS: Twenty-one newborns (41 ears) were recruited from the well-baby nursery at a tertiary referral center. All newborn infants who were born at 38 weeks' to 41 weeks' gestation with a normal birth weight (range: 2.5-4.5 kg) and who passed a newborn hearing screening test with distortion product otoacoustic emissions were enrolled. Ambient absorbance values were measured on frequencies ranging from 226 Hz to 6300 Hz (i.e., 250 Hz, 315 Hz, 400 Hz, 500 Hz, 620 Hz, 800 Hz, 1000 Hz, 1250 Hz, 1600 Hz, 2000 Hz, 2500 Hz, 3150 Hz, 4000 Hz, 5000 Hz, and 6300 Hz). The results of median absorbance were compared with the WBA values of Caucasian infants and Korean adults. RESULTS: The gestational age of the study group was 38 weeks ±â€¯6.67 days. In a gender comparison, absorbance of female neonate was significantly higher at 3150 Hz, 4000 Hz, and 5000 Hz than in male. Based on the test frequencies, the medians of the Korean infant WBA values and Caucasian infants are significantly different from one another, except at 1600 Hz, 3150 Hz, and 4000 Hz. The results of a median absorbance comparison between Korean infant and adults WBA values showed that the medians of the two studies were significantly different except at 1250 Hz. CONCLUSION: We analyzed the normative WBA values measured at ambient pressures in Korean newborns. The comparative analysis between the normative values of two different ethnic groups may infer a possible difference in the normative WBA values. The absorbance from Korean infant ears is substantially different from that from adult's ears. A large-scale study is required to establish normative WBA values to be used for the screening of outer and middle ear status in newborns.

Is auditory brainstem response a prognostic factor in patients with sudden sensorineural hearing loss?

Background: Serum thyroid hormone levels are closely related to the normal functioning of the cochlea. However, the relationship between initial auditory brainstem response (ABR) results and levels of thyroid hormone remained unclear until we adopted ABR as a prognostic factor in Idiopathic sudden sensorineural hearing loss (ISSNHL) patients. Objective: This investigation aimed to elucidate the association between ABR and outcomes in patients with ISSNHL. Material and methods: Thirty-three patients presenting with unilateral ISSNHL underwent blood sampling and ABR tests on the day of admission. The mean latencies of the ABR results were compared among the groups which were classified by ISSNHL outcome, based on Siegel's criteria. The association between the ABR results and the thyroid hormone serum levels (TSH, T3, and free T4) were assessed. Results: The overall successful recovery rate was 60.6% (n = 20). The mean latencies of all the ABR parameters were not significantly different between the different treatment outcome groups (Mann-Whitney U test). Wave V latency, III-V interval and I-V interval were negatively associated with T3 serum levels. Conclusion: The results indicate that clinical caution should be exercised when conducting ABR tests without assessing thyroid hormone levels.

Predicting cochlear dead regions in patients with hearing loss through a machine learning-based approach: A preliminary study.

We propose a machine learning (ML)-based model for predicting cochlear dead regions (DRs) in patients with hearing loss of various etiologies. Five hundred and fifty-five ears from 380 patients (3,770 test samples) diagnosed with sensorineural hearing loss (SNHL) were analyzed. A threshold-equalizing noise (TEN) test was applied to detect the presence of DRs. Data were collected on sex, age, side of the affected ear, hearing loss etiology, word recognition scores (WRS), and pure-tone thresholds at each frequency. According to the cause of hearing loss as diagnosed by the physician, we categorized the patients into six groups: 1) SNHL with unknown etiology; 2) sudden sensorineural hearing loss (SSNHL); 3) vestibular schwannoma (VS); 4) Meniere's disease (MD); 5) noise-induced hearing loss (NIHL); or 6) presbycusis or age-related hearing loss (ARHL). To develop a predictive model, we performed recursive partitioning and regression for classification, logistic regression, and random forest. The overall prevalence of one or more DRs in test ears was 20.36% (113 ears). Among the 3,770 test samples, the overall frequency-specific prevalence of DR was 6.7%. WRS, pure-tone thresholds at each frequency, disease type (VS or MD), and frequency information were useful for predicting DRs. Sex and age were not associated with detecting DRs. Based on these results, we suggest possible predictive factors for determining the presence of DRs. To improve the predictive power of the model, a more flexible model or more clinical features, such as the duration of hearing loss or risk factors for developing DRs, may be needed.

Benefit and predictive factors for speech perception outcomes in pediatric bilateral cochlear implant recipients.

INTRODUCTION: Despite recent advancement in the prediction of cochlear implant outcome, the benefit of bilateral procedures compared to bimodal stimulation and how we predict speech perception outcomes of sequential bilateral cochlear implant based on bimodal auditory performance in children remain unclear. OBJECTIVES: This investigation was performed: (1) to determine the benefit of sequential bilateral cochlear implant and (2) to identify the associated factors for the outcome of sequential bilateral cochlear implant. METHODS: Observational and retrospective study. We retrospectively analyzed 29 patients with sequential cochlear implant following bimodal-fitting condition. Audiological evaluations were performed; the categories of auditory performance scores, speech perception with monosyllable and disyllables words, and the Korean version of Ling. Audiological evaluations were performed before sequential cochlear implant with the bimodal fitting condition (CI1+HA) and one year after the sequential cochlear implant with bilateral cochlear implant condition (CI1+CI2). The good performance group (GP) was defined as follows; 90% or higher in monosyllable and bisyllable tests with auditory-only condition or 20% or higher improvement of the scores with CI1+CI2. Age at first implantation, inter-implant interval, categories of auditory performance score, and various comorbidities were analyzed by logistic regression analysis. RESULTS: Compared to the CI1+HA, CI1+CI2 provided significant benefit in categories of auditory performance, speech perception, and Korean version of Ling results. Preoperative categories of auditory performance scores were the only associated factor for being GP (odds ratio=4.38, 95% confidence interval - 95%=1.07-17.93, p=0.04). CONCLUSIONS: The children with limited language development in bimodal condition should be considered as the sequential bilateral cochlear implant and preoperative categories of auditory performance score could be used as the predictor in speech perception after sequential cochlear implant.

Standard Audiograms for Koreans Derived through Hierarchical Clustering Using Data from the Korean National Health and Nutrition Examination Survey 2009-2012.

Assessments of standardized region/population-specific audiological characteristics are needed for provision of effective rehabilitative services through reducing costs associated with hearing aids. This study aims to propose a set of standard audiograms representing the Korean population that were derived by analyzing data from the 2009-2012 Korea National Health and Nutrition Examination Survey (KNHANES), a nationwide epidemiologic study conducted by Korean government organizations. Standard audiograms were derived by applying a hierarchical clustering method from recorded audiologic data that were obtained independently at 6 frequencies for each ear: 0.5, 1.0, 2.0, 3.0, 4.0, and 6.0 kHz (in dB HL). To derive the optimal number of clusters of the desired standard audiograms, cubic clustering criterion, pseudo-F-, and pseudo-t2-statistics were calculated. These analyses resulted in 29 clusters representing a standard audiogram of the South Korean population. Eighteen of the clusters represented normal hearing audiograms (73.11%), while 11 represented hearing-impaired (HI) standard audiograms (27.89%). Of the 11 HI audiograms, 7 were defined as flat-type (17.81%), while the remaining 4 were defined as sloping-type (9.08%). In conclusion, 29 audiograms representing standard audiograms for the Korean population have been derived using KNHANES data. Improved understanding of the characteristics of each cluster may be helpful for development of more personalized, fixed-setting hearing aids.

Preparation of a promising angiogenesis PET imaging agent: 68Ga-labeled c(RGDyK)-isothiocyanatobenzyl-1,4,7-triazacyclononane-1,4,7-triacetic acid and feasibility studies in mice.

UNLABELLED: Arg-Gly-Asp (RGD) derivatives have been labeled with various radioisotopes for the imaging of angiogenesis in ischemic tissue, in which alpha(v)beta(3) integrin plays an important role. In this study, cyclic Arg-Gly-Asp-D-Tyr-Lys [c(RGDyK)] was conjugated with 2-(p-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid (SCN-Bz-NOTA) and then labeled with (68)Ga. The labeled RGD so produced was subjected to an in vitro binding assay and in vivo biodistribution and PET studies. METHODS: A mixture of SCN-Bz-NOTA (660 nmol) and c(RGDyK) (600 nmol) in 0.1 M sodium carbonate buffer (pH 9.5) was allowed to react for 20 h at room temperature in the dark for thiourea bond formation. The conjugate obtained was purified by semipreparative high-performance liquid chromatography (HPLC). The purified c(RGDyK)-SCN-Bz-NOTA (NOTA-RGD) was then labeled with (68)Ga from a (68)Ge/(68)Ga generator and purified by semipreparative HPLC. A competitive binding assay for c(RGDyK) and NOTA-RGD was performed with (125)I-c(RGDyK) as a radioligand and alpha(v)beta(3) integrin-coated plates as a solid phase. (68)Ga-NOTA-RGD (0.222 MBq/100 microL) was injected, through a tail vein, into mice with hind limb ischemia and into mice bearing human colon cancer SNU-C4 xenografts. Biodistribution and imaging studies were performed at 1 and 2 h after injection. RESULTS: The labeling of NOTA-RGD with (68)Ga was straightforward. The K(i) values of c(RGDyK) and NOTA-RGD were 1.3 and 1.9 nM, respectively. In the biodistribution study, the mean +/- SD uptake of (68)Ga-NOTA-RGD by ischemic muscles was 1.6+/-0.2 percentage injected dose per gram (%ID/g); this uptake was significantly blocked by cold c(RGDyK) to 0.6+/-0.3 %ID/g (P<0.01). Tumor uptake was 5.1+/-1.0 %ID/g, and the tumor-to-blood ratio was 10.3+/-4.8. Small-animal PET revealed rapid excretion through the urine and high levels of tumor and kidney uptake. CONCLUSION: Stable (68)Ga-NOTA-RGD was obtained in a straightforward manner at a high yield and showed a high affinity for alpha(v)beta(3) integrin, specific uptake by angiogenic muscles, a high level of uptake by tumors, and rapid renal excretion. (68)Ga-NOTA-RGD was found to be a promising radioligand for the imaging of angiogenesis.

An approach for assessing human exposures to chemical mixtures in the environment.

Humans are exposed daily to multiple chemicals, including incidental exposures to complex chemical mixtures released into the environment and to combinations of chemicals that already co-exist in the environment because of previous releases from various sources. Exposures to chemical mixtures can occur through multiple pathways and across multiple routes. In this paper, we propose an iterative approach for assessing exposures to environmental chemical mixtures; it is similar to single-chemical approaches. Our approach encompasses two elements of the Risk Assessment Paradigm: Problem Formulation and Exposure Assessment. Multiple phases of the assessment occur in each element of the paradigm. During Problem Formulation, analysts identify and characterize the source(s) of the chemical mixture, ensure that dose-response and exposure assessment measures are concordant, and develop a preliminary evaluation of the mixture's fate. During Exposure Assessment, analysts evaluate the fate of the chemicals comprising the mixture using appropriate models and measurement data, characterize the exposure scenario, and estimate human exposure to the mixture. We also describe the utility of grouping the chemicals to be analyzed based on both physical-chemical properties and an understanding of environmental fate. In the article, we also highlight the need for understanding of changes in the mixture composition in the environment due to differential transport, differential degradation, and differential partitioning to other media. The Results section describes the application of the method to various chemical mixtures, highlighting issues associated with assessing exposures to chemical mixtures in the environment.