BackgroundIn evaluating hearing disability in medicolegal work, the apportionment of age- and gender-related sensorineural hearing loss should be considered as a prior factor, especially for the elderly. However, in the literature written in the English language no studies have reported on the age- and gender-related mean hearing threshold for the South Korean population.ObjectiveThis study aimed to identify the mean hearing thresholds in the South Korean population to establish reference data and to identify the age- and gender-related characteristics.MethodsThis study is based on the Korea National Health and Nutrition Examination Survey (KNHANES) 2010–2012, which was conducted by the Korean government, the data of which was disclosed to the public. A total of 15,606 participants (unweighted) representing 33,011,778 Koreans (weighted) with normal tympanic membrane and no history of regular or occupational noise exposure were selected and analyzed in this study. The relationship between the hearing threshold level and frequency, age, and gender was investigated and analyzed in a highly-screened population by considering the sample weights of a complex survey design.ResultsA gender ratio difference was found between the unweighted and the weighted designs: male:female, 41.0%: 59.0% (unweighted, participants) vs. 47.2%:52.8% (weighted, representing population). As age increased, the hearing threshold increased for all frequencies. Hearing thresholds of 3 kHz, 4 kHz, and 6 kHz showed a statistical difference between both genders for people older than 30, with the 4 kHz frequency showing the largest difference. This paper presents details about the mean hearing threshold based on age and gender.ConclusionsThe data from KNHANES 2010–2012 showed gender differences at hearing thresholds of 3 kHz, 4 kHz, and 6 kHz in a highly-screened population. The most significant gender difference in relation to hearing threshold was observed at 4 kHz. The hearing thresholds at all of the tested frequencies worsened with increasing age. The mean hearing thresholds suggested in this study will be useful for the formulation of healthcare-related hearing policies and used as reference data for disability ratings for hearing loss due to various causes.

In this paper, we present the results of coblation nasal septal swell body (NSB) reduction for the treatment of nasal obstruction in patients with abnormally thickened NSB. The study design was a retrospective clinical series conducted at a single tertiary medical center. Eight patients underwent coblation NSB reduction. Pre-operative and post-operative nasal functions were evaluated by acoustic rhinometry and subjective symptom scales. We also analyzed pre-operative CT scan images and nasal endoscopic findings. The mean maximal NSB width was 16.4 ± 2.2 mm on pre-operative coronal CT scan images. The mean visual analog scale score for nasal obstruction was decreased from preoperative 7.63 ± 0.99 points to 3.88 ± 0.92 points (postoperative 3 months), 4.16 ± 0.78 points (postoperative 6 months), and 4.63 ± 0.69 points (postoperative 1 year). Six out of the eight patients were satisfied with the clinical outcome at 1 year after the procedure. To the best of our knowledge, coblation NSB reduction has not yet been reported in the medical literature. Our results show that it can be an effective treatment modality for nasal valve narrowing in patients with abnormally thickened NSB.

In the present work, Corynebacterium glutamicum was metabolically engineered for the enantioselective synthesis of non-proteinogenic amino acids as valuable building blocks for pharmaceuticals and agrochemicals. The novel bio-catalytic activity of C. glutamicum was obtained by heterologous expression of the branched chain aminotransferase IlvE from Escherichia coli. Upon this modification, the recombinant cells converted the α-keto acid precursor 2-(3-hydroxy-1-adamantyl)-2-oxoethanoic acid (HOAE) into the corresponding amino acid 2-(3-hydroxy-1-adamantyl)-(2S)-amino ethanoic acid (HAAE). Similarly, also L-tert-leucine could be obtained from trimethyl pyruvate indicating a broader applicability of the novel strategy. In both cases, the amino group donor glutamate was supplied from the endogenous metabolism of the recombinant producer. Hereby, the uptake of the precursor and secretion of the product was supported by an enhanced cell permeability through treatment of ethambutol, which inhibits arabinosyl transferases involved in cell wall biosynthesis. The excretion of HAAE into the reaction medium was linked to the secretion of glutamate, indicating a similar mechanism for the export of both compounds. On the other hand, the efflux of L-tert-leucine appeared to be driven by active transport. Subsequent bioprocess engineering enabled HAAE and L-tert-leucine to be produced at a rate of 0.21 and 0.42 mmol (g dry cells)⁻¹  h⁻¹, respectively up to a final product titer of 40 mM. Beyond the given examples, integrated metabolic and cell envelop engineering might extend the production of a variety of other non-proteinogenic amino acids as well as chiral amines by C. glutamicum.

BackgroundWhen evaluating hearing disability in medicolegal cases, an average of thresholds at several frequencies is calculated using pure tone audiometry. Occasionally, there are instances in which thresholds at certain frequencies are omitted. One typical example is the threshold at 3 kHz (H3k). The American Academy of Otolaryngology–Head and Neck Surgery Committee on Hearing and Equilibrium (1995) suggested that the average of thresholds at 2 kHz and 4 kHz (H24k) could replace H3k for a comparison of results between studies. However, to the best of our knowledge, there is no report in the literature that compares H3k and H24k.ObjectiveThis study aimed to investigate the agreement between H3k and H24k.MethodsThis study is based on the Korea National Health and Nutrition Examination Survey (KNHANES) 2010–2012, which was conducted by the Korean government. A total of 18,472 participants (unweighted) who represented 39,357,497 Koreans (weighted) were included. To verify the agreement of H3k and H24k, a paired t-test, Cohen’s d, Pearson’s correlation, Cronbach’s coefficient, intraclass correlation coefficient (ICC), a Bland–Altman plot, and linear regression analysis were used.ResultsThe means of H3k and H24k were 16.2 dBHL and 16.6 dBHL, respectively. They were significantly different in a paired t-test (p<0.0001), which resulted from the large sample size. In contrast, the effect size (Cohen’s d) was 0.02, which meant that the two groups nearly overlapped. The means showed strong correlation: Pearson’s correlation coefficient = 0.92, Cronbach’s alpha = 0.96, and ICC = 0.92. A strong linear predictive relationship between H3k and H24k was found: y = –0.6821 + 1.0186x, where x = H24k, y = H3k, and p<0.0001. However, the Bland–Altman plot showed large upper and lower limits of agreement (LOA) of 15.0 dBHL and –15.8 dBHL, respectively. Irrespective of age and degree of the four-tone average (0.5, 1, 2, and 3 kHz) hearing loss or thresholds at 2 kHz, 3 kHz, and 4 kHz, the absolute LOAs were greater than 10 dBHL.ConclusionsDespite a very strong correlation between the two thresholds, H3k and H24k showed clinically large LOAs. Therefore, it would be improper to substitute H24k for H3k in an individual requesting a hearing disability rating. However, since the overall means of the H3k and H24k samples were nearly equal, H24k can replace H3k for a mean comparison of results between studies. This result supports the 1995 Committee on Hearing and Equilibrium guideline.