The Serial Interval of COVID-19 in Korea: 1,567 Pairs of Symptomatic Cases from Contact Tracing

Although coronavirus disease 2019 (COVID-19) is an ongoing pandemic, the mean serial interval was measured differently across nations. Through the Korean national COVID-19 contact tracing system, we were able to investigate personal contacts in all symptomatic cases in Korea from January 20 to August 3, 2020. The mean serial interval was calculated by the duration between the symptom onset of the infector and infectee, and became shorter after the case definition changed to include not-imported cases in Korea on February 20, 2020. The mean serial interval before and after this fifth case definition was 6.12 and 3.93 days based on the infectors' symptom onset date, respectively, and 4.02 days in total with the median of 3 days. Older age and women lead to longer serial intervals.

The Serial Interval of COVID-19 in Korea: 1,567 Pairs of Symptomatic Cases from Contact Tracing

Although coronavirus disease 2019 (COVID-19) is an ongoing pandemic, the mean serial interval was measured differently across nations. Through the Korean national COVID-19 contact tracing system, we were able to investigate personal contacts in all symptomatic cases in Korea from January 20 to August 3, 2020. The mean serial interval was calculated by the duration between the symptom onset of the infector and infectee, and became shorter after the case definition changed to include not-imported cases in Korea on February 20, 2020. The mean serial interval before and after this fifth case definition was 6.12 and 3.93 days based on the infectors' symptom onset date, respectively, and 4.02 days in total with the median of 3 days. Older age and women lead to longer serial intervals.

In Vivo Vibration Measurement of Middle Ear Structure Using Doppler Optical Coherence Tomography: Preliminary Study

OBJECTIVES: Doppler optical coherence tomography (DOCT) is useful for both, the spatially resolved measurement of the tympanic membrane (TM) oscillation and high-resolution imaging. We demonstrated a new technique capable of providing real-time two-dimensional Doppler OCT image of rapidly oscillatory latex mini-drum and in vivo rat TM and ossicles. METHODS: Using DOCT system, the oscillation of sample was measured at frequency range of 1–4 kHz at an output of 15 W. After the sensitivity of the DOCT system was verified using a latex mini-drum consisting of a 100 μm-thick latex membrane, changes in displacement of the umbo and contacted area between TM and malleus in normal and pathologic conditions. RESULTS: The oscillation cycles of the mini-drum for stimulus frequencies were 1.006 kHz for 1 kHz, 2.012 kHz for 2kHz, and 3.912 kHz for 4 kHz, which means that the oscillation cycle of the mini-drum become short in proportional to the frequency of stimuli. The oscillation cycles of umbo area and the junction area in normal TM for frequencies of the stimuli showed similar integer ratio with the data of latex mini-drum for stimuli less than 4 kHz. In the case of middle ear effusion condition, the Doppler signal showed a tendency of attenuation in all frequencies, which was prominent at 1 kHz and 2 kHz. CONCLUSION: The TM vibration under sound stimulation with frequencies from 1 kHz to 4 kHz in normal and pathologic conditions was demonstrated using signal demodulation method in in vivo condition. The OCT technology could be helpful for functional and structural assessment as an optional modality.

Assessment of cortical bone microdamage following insertion of microimplants using optical coherence tomography: a preliminary study / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

OBJECTIVES@#The study was done to evaluate the efficacy of optical coherence tomography (OCT), to detect and analyze the microdamage occurring around the microimplant immediately following its placement, and to compare the findings with micro-computed tomography (μCT) images of the samples to validate the result of the present study.@*METHODS@#Microimplants were inserted into bovine bone samples. Images of the samples were obtained using OCT and μCT. Visual comparisons of the images were made to evaluate whether anatomical details and microdamage induced by microimplant insertion were accurately revealed by OCT.@*RESULTS@#The surface of the cortical bone with its anatomical variations is visualized on the OCT images. Microdamage occurring on the surface of the cortical bone around the microimplant can be appreciated in OCT images. The resulting OCT images were compared with the μCT images. A high correlation regarding the visualization of individual microcracks was observed. The depth penetration of OCT is limited when compared to μCT.@*CONCLUSIONS@#OCT in the present study was able to generate high-resolution images of the microdamage occurring around the microimplant. Image quality at the surface of the cortical bone is above par when compared with μCT imaging, because of the inherent high contrast and high-resolution quality of OCT systems. Improvements in the imaging depth and development of intraoral sensors are vital for developing a real-time imaging system and integrating the system into orthodontic practice.

The Association between Fat Mass, Lean Mass and Bone Mineral Density in Premenopausal Women in Korea: A Cross-Sectional Study / 가정의학회지

BACKGROUND: We investigated the association between body composition, especially truncal or non-truncal fat mass (FM), and bone mineral density (BMD) in premenopausal women in Korea. METHODS: A cross-sectional study was performed using data from the Korea National Health and Nutrition Examination Survey IV and V (2008–2011). Total lean mass (LM), total FM (TFM), truncal FM, and non-truncal FM, and BMD of the total femur, femoral neck (FN), and lumbar spine were measured using dual-energy X-ray absorptiometry. The association between body composition and BMD was analyzed using multiple linear regression. The risk of low BMD according to quartiles of TFM, truncal FM, and non-truncal FM was calculated using logistic regression. Subgroup analysis according to body mass index was also performed. RESULTS: In 4,343 premenopausal women, total LM was positively associated with BMD regardless of weight adjustment. TFM, truncal FM, and non-truncal FM were inversely associated with BMD after adjusting for weight. Odds ratios (ORs) for low BMD and 95% confidence intervals (CIs) of the highest quartile of TFM, truncal FM, and non-truncal FM compared with the lowest quartile were calculated. The risk of low BMD of the FN was higher in the highest quartile of TFM (OR, 4.48; 95% CI, 1.11–18.01) and truncal FM (OR, 5.48; 95% CI, 1.75–17.20). Truncal FM and not-truncal FM had an inverse association with BMD in the non-obese and obese subgroups of women. CONCLUSION: Total LM has a protective effect on BMD and FM can have a detrimental effect on BMD besides its skeletal loading effect.

The Feasibility Study of Contrast-enhanced Ultrasound Using a 3 Dimension Transducer for Tumor Volume Measurement in Rabbit Hepatic VX2 Carcinoma Comparison with 2 Dimension Ultrasound and 3 Dimension Ultrasound without Contrast: Preliminary Results

BACKGROUND/AIMS: To investigate the feasibility of tumor volume measurement using contrastenhanced ultrasound (US) with 3 dimension transducer (3D CEUS) in rabbit hepatic VX2 carcinoma. METHODS: Three different tumor volume measurements, including 2D US using the equation, 4/3(π)(abc), 3D US without contrast, and 3D CEUS were performed in 35 rabbit hepatic VX2 carcinomas. With the tumor volume from computerized tomography (CT) as a reference standard, we compared difference between CT volume and each different US tumor volume. The mean difference and correlation coefficient between each US volume measurement and CT volume were analyzed. RESULTS: Tumor volume measurement using 3D CEUS and 2D US using equation showed no statistical difference compared to CT volume (0.276 cm3, 0.212 cm3, and 0.263 cm3 vs. 0.306 cm3, 0.247 cm3, 0.276 cm3, P>0.05). However, 3D CEUS provided the highest correlation coefficient with CT volume (R=0.835 and 0.720) and the highest intraclass correlation (0.973 and 0.993). 3D CEUS provided a smaller mean difference with CT volume (0.016 cm3 and 0.033 cm3) than 2D US, showing 3D CEUS's accurate measurement of tumor volume. CONCLUSIONS: Due to its highly accurate, reliable, and reproducible measurements of tumor volume, 3D CEUS may be useful for predicting the therapeutic response evaluation after treatment.

Association between Body Mass Index and Quality of Life in Elderly People over 60 Years of Age / 가정의학회지

BACKGROUND: The Korean population is aging rapidly and the number of health threats is increasing. The elderly obese population is also increasing and this study aimed to evaluate the association between body mass index (BMI) and health-related quality of life in the elderly Korean population. METHODS: The Korean version Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) was administered to elderly subjects (≥60 years) selected from welfare and health centers, and university hospitals. Sociodemographic information and subjects' height and weight were also recorded. RESULTS: The study population's mean age was 74.2±7.1 years, and the average BMI was 24.5±3.2 kg/m². The 542 participants were segregated based on BMI quartiles. The SF-36 scores were compared among the sex-stratified quartile groups after adjusting for age, education level, income, smoking, alcohol, and arthritis diagnosis. The SF-36 scores were compared for four BMI quartiles stratified by sex, after adjusting for age, education level, income, smoking, alcohol consumption, and arthritis diagnosis. Men in the Q3 and Q4 groups had higher mental health scores than men in Q2 group. Additionally, men in the Q3 group had higher social function scores than those in the Q2 and Q4 groups. No differences were observed for the remaining six domains; no significant score differences were observed in any of the survey domains for the female subjects. CONCLUSION: There was no significant association between a high BMI and a low quality of life in the elderly Korean population selected from hospitals and welfare centers, as assessed using the SF-36 scores.

Erratum: Optical Coherence Tomography for the Diagnosis and Evaluation of Human Otitis Media

We made two mistakes in our recently published article. We are correcting the authorship and funding information.

Optical Coherence Tomography for the Diagnosis and Evaluation of Human Otitis Media

We report the application of optical coherence tomography (OCT) to the diagnosis and evaluation of otitis media (OM). Whereas conventional diagnostic modalities for OM, including standard and pneumatic otoscopy, are limited to visualizing the surface of the tympanic membrane (TM), OCT effectively reveals the depth-resolved microstructure below the TM with very high spatial resolution, with the potential advantage of its use for diagnosing different types of OM. We examined the use of 840-nm spectral domain-OCT (SD-OCT) clinically, using normal ears and ears with the adhesive and effusion types of OM. Specific features were identified in two-dimensional OCT images of abnormal TMs, compared to images of healthy TMs. Analysis of the A-scan (axial depth scan) identified unique patterns of constituents within the effusions. The OCT images could not only be used to construct a database for the diagnosis and classification of OM but OCT might also represent an upgrade over current otoscopy techniques.

Optical Coherence Tomography for the Diagnosis and Evaluation of Human Otitis Media

We report the application of optical coherence tomography (OCT) to the diagnosis and evaluation of otitis media (OM). Whereas conventional diagnostic modalities for OM, including standard and pneumatic otoscopy, are limited to visualizing the surface of the tympanic membrane (TM), OCT effectively reveals the depth-resolved microstructure below the TM with very high spatial resolution, with the potential advantage of its use for diagnosing different types of OM. We examined the use of 840-nm spectral domain-OCT (SD-OCT) clinically, using normal ears and ears with the adhesive and effusion types of OM. Specific features were identified in two-dimensional OCT images of abnormal TMs, compared to images of healthy TMs. Analysis of the A-scan (axial depth scan) identified unique patterns of constituents within the effusions. The OCT images could not only be used to construct a database for the diagnosis and classification of OM but OCT might also represent an upgrade over current otoscopy techniques.