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1.  Depression Screening Using Daily Mental-Health Ratings from a Smartphone Application for Breast Cancer Patients 
Mobile mental-health trackers are mobile phone apps that gather self-reported mental-health ratings from users. They have received great attention from clinicians as tools to screen for depression in individual patients. While several apps that ask simple questions using face emoticons have been developed, there has been no study examining the validity of their screening performance.
In this study, we (1) evaluate the potential of a mobile mental-health tracker that uses three daily mental-health ratings (sleep satisfaction, mood, and anxiety) as indicators for depression, (2) discuss three approaches to data processing (ratio, average, and frequency) for generating indicator variables, and (3) examine the impact of adherence on reporting using a mobile mental-health tracker and accuracy in depression screening.
We analyzed 5792 sets of daily mental-health ratings collected from 78 breast cancer patients over a 48-week period. Using the Patient Health Questionnaire-9 (PHQ-9) as the measure of true depression status, we conducted a random-effect logistic panel regression and receiver operating characteristic (ROC) analysis to evaluate the screening performance of the mobile mental-health tracker. In addition, we classified patients into two subgroups based on their adherence level (higher adherence and lower adherence) using a k-means clustering algorithm and compared the screening accuracy between the two groups.
With the ratio approach, the area under the ROC curve (AUC) is 0.8012, indicating that the performance of depression screening using daily mental-health ratings gathered via mobile mental-health trackers is comparable to the results of PHQ-9 tests. Also, the AUC is significantly higher (P=.002) for the higher adherence group (AUC=0.8524) than for the lower adherence group (AUC=0.7234). This result shows that adherence to self-reporting is associated with a higher accuracy of depression screening.
Our results support the potential of a mobile mental-health tracker as a tool for screening for depression in practice. Also, this study provides clinicians with a guideline for generating indicator variables from daily mental-health ratings. Furthermore, our results provide empirical evidence for the critical role of adherence to self-reporting, which represents crucial information for both doctors and patients.
PMCID: PMC4990716  PMID: 27492880
depression; smartphone applications; mental health; breast cancer (neoplasms)
2.  A Spray-On Carbon Nanotube Artificial Neuron Strain Sensor for Composite Structural Health Monitoring 
Sensors (Basel, Switzerland)  2016;16(8):1171.
We present a nanocomposite strain sensor (NCSS) to develop a novel structural health monitoring (SHM) sensor that can be easily installed in a composite structure. An NCSS made of a multi-walled carbon nanotubes (MWCNT)/epoxy composite was installed on a target structure with facile processing. We attempted to evaluate the NCSS sensing characteristics and benchmark compared to those of a conventional foil strain gauge. The response of the NCSS was fairly good and the result was nearly identical to the strain gauge. A neuron, which is a biomimetic long continuous NCSS, was also developed, and its vibration response was investigated for structural damage detection of a composite cantilever. The vibration response for damage detection was measured by tracking the first natural frequency, which demonstrated good result that matched the finite element (FE) analysis.
PMCID: PMC5017337  PMID: 27472332
carbon nanotube; artificial neuron; strain sensor; composites; structural health monitoring; piezoresistivity; damage detection
3.  Characteristics of BRCA1/2 Mutation-Positive Breast Cancers in Korea: A Comparison Study Based on Multicenter Data and the Korean Breast Cancer Registry 
Journal of Breast Cancer  2014;17(2):129-135.
Mutations in BRCA genes are the main cause of hereditary breast cancer in Korea. The aim of this study was to investigate the characteristics of breast cancers involving BRCA1 (BRCA1 group) and BRCA2 (BRCA2 group) mutations.
We retrospectively reviewed the medical records of patients with BRCA1 (BRCA1 group) or BRCA2 (BRCA2 group) mutation positive breast cancer from multiple centers and compared the data to that of the Korean Breast Cancer Society registry (registry group).
The patients of the BRCA1 group were diagnosed at a younger age (median age, 37 years) and had tumors of higher histological (61.3% with histological grade 3) and nuclear (37.5% with nuclear grade 3) grade than those of the registry group. In addition, the frequency of ductal carcinoma in situ in the BRCA1 group was lower (3.7%) than in the registry group, and the BRCA1 group were more likely to be triple-negative breast cancer (61.3%). Patients in the BRCA2 group were also younger at diagnosis (mean age, 41 years) and were more likely to have involvement of the axillary node than the registry group (45.5% vs. 33.5%, p=0.002). The BRCA1 and BRCA2 groups did not show a correlation between tumor size and axillary node involvement.
We report the characteristics of BRCA mutation positive breast cancer patients in the Korean population through multicenter data and nation-wide breast cancer registry study. However, BRCA-mutated breast cancers appear highly complex, and further research on their molecular basis is needed in Korea.
PMCID: PMC4090314  PMID: 25013433
BRCA1 genes; BRCA2 genes; Breast neoplasms; Korea
4.  Daily Collection of Self-Reporting Sleep Disturbance Data via a Smartphone App in Breast Cancer Patients Receiving Chemotherapy: A Feasibility Study 
Improvements in mobile telecommunication technologies have enabled clinicians to collect patient-reported outcome (PRO) data more frequently, but there is as yet limited evidence regarding the frequency with which PRO data can be collected via smartphone applications (apps) in breast cancer patients receiving chemotherapy.
The primary objective of this study was to determine the feasibility of an app for sleep disturbance-related data collection from breast cancer patients receiving chemotherapy. A secondary objective was to identify the variables associated with better compliance in order to identify the optimal subgroups to include in future studies of smartphone-based interventions.
Between March 2013 and July 2013, patients who planned to receive neoadjuvant chemotherapy for breast cancer at Asan Medical Center who had access to a smartphone app were enrolled just before the start of their chemotherapy and asked to self-report their sleep patterns, anxiety severity, and mood status via a smartphone app on a daily basis during the 90-day study period. Push notifications were sent to participants daily at 9 am and 7 pm. Data regarding the patients’ demographics, interval from enrollment to first self-report, baseline Beck’s Depression Inventory (BDI) score, and health-related quality of life score (as assessed using the EuroQol Five Dimensional [EQ5D-3L] questionnaire) were collected to ascertain the factors associated with compliance with the self-reporting process.
A total of 30 participants (mean age 45 years, SD 6; range 35-65 years) were analyzed in this study. In total, 2700 daily push notifications were sent to these 30 participants over the 90-day study period via their smartphones, resulting in the collection of 1215 self-reporting sleep-disturbance data items (overall compliance rate=45.0%, 1215/2700). The median value of individual patient-level reporting rates was 41.1% (range 6.7-95.6%). The longitudinal day-level compliance curve fell to 50.0% at day 34 and reached a nadir of 13.3% at day 90. The cumulative longitudinal compliance curve exhibited a steady decrease by about 50% at day 70 and continued to fall to 45% on day 90. Women without any form of employment exhibited the higher compliance rate. There was no association between any of the other patient characteristics (ie, demographics, and BDI and EQ5D-3L scores) and compliance. The mean individual patient-level reporting rate was higher for the subgroup with a 1-day lag time, defined as starting to self-report on the day immediately after enrollment, than for those with a lag of 2 or more days (51.6%, SD 24.0 and 29.6%, SD 25.3, respectively; P=.03).
The 90-day longitudinal collection of daily self-reporting sleep-disturbance data via a smartphone app was found to be feasible. Further research should focus on how to sustain compliance with this self-reporting for a longer time and select subpopulations with higher rates of compliance for mobile health care.
PMCID: PMC4051741  PMID: 24860070
mobile applications; self report; compliance; breast cancer
5.  Similarity in Neuronal Firing Regimes across Mammalian Species 
The Journal of Neuroscience  2016;36(21):5736-5747.
The architectonic subdivisions of the brain are believed to be functional modules, each processing parts of global functions. Previously, we showed that neurons in different regions operate in different firing regimes in monkeys. It is possible that firing regimes reflect differences in underlying information processing, and consequently the firing regimes in homologous regions across animal species might be similar. We analyzed neuronal spike trains recorded from behaving mice, rats, cats, and monkeys. The firing regularity differed systematically, with differences across regions in one species being greater than the differences in similar areas across species. Neuronal firing was consistently most regular in motor areas, nearly random in visual and prefrontal/medial prefrontal cortical areas, and bursting in the hippocampus in all animals examined. This suggests that firing regularity (or irregularity) plays a key role in neural computation in each functional subdivision, depending on the types of information being carried.
SIGNIFICANCE STATEMENT By analyzing neuronal spike trains recorded from mice, rats, cats, and monkeys, we found that different brain regions have intrinsically different firing regimes that are more similar in homologous areas across species than across areas in one species. Because different regions in the brain are specialized for different functions, the present finding suggests that the different activity regimes of neurons are important for supporting different functions, so that appropriate neuronal codes can be used for different modalities.
PMCID: PMC4879195  PMID: 27225764
firing irregularity/regularity; interspecies similarity; neuronal firing pattern; neuronal firing regime
6.  The Clinical Impact of 21-Gene Recurrence Score on Treatment Decisions for Patients with Hormone Receptor-Positive Early Breast Cancer in Korea 
The 21-gene (Oncotype DX) recurrence score (RS) assay is useful in predicting the benefits of adjuvant chemotherapy for early breast cancer patients and is widely used in Western countries. However, to date, it has not gained much popularity in East Asia. We analyzed the results from five institutions’ experience from using the 21-gene assay and examined the impact of assay results on decision making of chemotherapy in Korean breast cancer patients and the associations between RS and clinicopathologic characteristics.
Materials and Methods
The 21-gene assay was performed on 212 patients with estrogen receptor-positive early breast cancer in five institutions. Each center made systemic treatment decisions both before and after the knowledge of assay results.
Among the 212 patients, 132 (62.3%) had a low RS of < 18, 60 (28.3%) had an intermediate RS of 18-30, and 20 (9.4%) had a high RS of ≥ 31. Histologic grade, presence of micrometastases, Ki-67, and presence of lymphatic invasion were statistically associated with the RS results. Treatment decisions were changed in 115 of 212 patients (54.2%) in 109 of 212 (51.4%) from chemotherapy plus hormone therapy to hormone therapy, and in six of 212 (2.8%) from hormone therapy to chemotherapy plus hormone therapy.
The 21-gene breast cancer assay proved to have a significant impact on treatment decision- making. The test reduces chemotherapy use in more than 50% of Korean estrogen receptor-positive, early breast cancer patients.
PMCID: PMC4398124  PMID: 25381828
Breast neoplasms; Oncotype DX; Adjuvant chemotherapy
7.  A multi-institutional study of the prevalence of BRCA1 and BRCA2 large genomic rearrangements in familial breast cancer patients 
BMC Cancer  2014;14:645.
Large genomic rearrangements (LGRs) in the BRCA1/2 genes are frequently observed in breast cancer patients who are negative for BRCA1/2 small mutations. Here, we examined 221 familial breast cancer patients from 37 hospitals to estimate the contribution of LGRs, in a nationwide context, to the development of breast cancer.
Direct sequencing or mutation scanning followed by direct sequencing was performed to screen small mutations. BRCA1/2 small mutation-negative patients were screened for the presence of LGRs using a multiple ligation-dependent probe amplification (MLPA) assay.
Using a combined strategy to detect the presence of small mutations and LGRs, we identified BRCA1/2 small mutations in 78 (35.3%) out of 221 familial breast cancer patients and BRCA1 LGRs in 3 (2.1%) out of 143 BRCA1/2 small mutation-negative patients: the deletion of exons 11–13, the deletion of exons 13–15, and whole gene deletion of exons 1-24. The novel deletion of exons 11–13 is thought to result from a non-homologous recombination event mediated by a microhomology sequence comprised of 3 or 4 base pairs: c.3416_4357 + 1863delins187 (NG_005905.2: g.33369_44944delins187).
In this study, we showed that LGRs were found in 3.7% (3/81) of the patients who had mutations in BRCA1 or BRCA2, and 7.5% (3/40) of patients with mutations in BRCA1. This suggests that the contribution of LGRs to familial breast cancer in this population might be comparable to that in other ethnic populations. Given these findings, an MLPA to screen for mutations in the BRCA1 gene is recommended as an initial screening test in highly selective settings.
PMCID: PMC4164743  PMID: 25176351
Breast cancer; Hereditary cancer; Large genomic rearrangement; BRCA1; BRCA2
8.  Reliability of the Percent Density in Digital Mammography with a Semi-Automated Thresholding Method 
Journal of Breast Cancer  2014;17(2):174-179.
The reliability of the quantitative measurement of breast density with a semi-automated thresholding method (Cumulus™) has mainly been investigated with film mammograms. This study aimed to evaluate the intrarater reproducibility of percent density (PD) by Cumulus™ with digital mammograms.
This study included 1,496 craniocaudal digital mammograms from the unaffected breast of breast cancer patients. One rater reviewed each mammogram and estimated the PD using the Cumulus™ method. All images were reassessed by the same rater 1 month later without reference to the previously assigned values. The repeatability of the PD was evaluated by an intraclass correlation coefficient (ICC). All patients were grouped based on their body mass index (BMI), age, family history of breast cancer, breastfeeding history and breast area (calculated with Cumulus™), and subgroup analysis for the ICC of each group was performed. All patients were categorized by their Breast Imaging Reporting and Data System (BI-RADS) density pattern, and the mean and standard deviation of the PD by each BI-RADS categories were compared.
The ICC for the PD was 0.94, indicating excellent repeatability. The discrepancy between the paired PD values ranged from 0 to 23.93, with an average of 3.90 (standard deviation=3.39). The subgroup ICCs for the PD ranged from 0.88 to 0.96, indicating excellent reliability in all subgroups regardless of patient variables. The ICCs of the PD for the high-risk (BI-RADS 3 and 4) and low-risk (BI-RADS 1 and 2) groups were 0.90 and 0.88, respectively.
This study suggests that PD calculated with digital mammograms has an acceptable reliability regardless of patient age, BMI, family history of breast cancer, breastfeeding history, breast size, and BI-RADS density pattern.
PMCID: PMC4090321  PMID: 25013440
Breast; Mammography; Observer variation
9.  Survival Outcome of Combined GnRH Agonist and Tamoxifen Is Comparable to That of Sequential Adriamycin and Cyclophosphamide Chemotherapy Plus Tamoxifen in Premenopausal Patients with Lymph-Node–Negative, Hormone-Responsive, HER2-Negative, T1-T2 Breast Cancer 
The purpose of this study was to compare treatment outcomes between combined gonadotropin-releasing hormone agonist and tamoxifen (GnRHa+T) and sequential adriamycin and cyclophosphamide chemotherapy and tamoxifen (AC->T) in premenopausal patients with hormone-responsive, lymph-node–negative breast cancer.
Materials and Methods
In total, 994 premenopausal women with T1-T2, lymph-node–negative, hormone-receptor-positive, HER2-negative breast cancer between January 2003 and December 2008 were included in this retrospective cohort study. GnRHa+T and AC->T were administered to 608 patients (61.2%) and 386 patients (38.8%), respectively. Propensity score matching and inverse probability weighting were applied to the original cohort, and 260 patients for each treatment arm were included in the final analysis. Recurrence-free, cancer-specific, and overall survival was compared between the two treatment groups.
A total of 994 patients were followed up for a median of 7.4 years (range, 0.5 to 11.4 years). The 5-year follow-up rate was 98.7%, and 13 patients were lost to follow-up. In propensity-matched cohorts (n=520), there was no difference in recurrence-free, cancer-specific, and overall survival rates between the two treatment groups (p=0.306, p=0.212, and p=0.102, respectively), and this was maintained after applying inverse probability weighting.
GnRHa+T is a reasonable alternative to AC->T in patients with premenopausal, hormone-responsive, HER2-negative, lymph-node–negative, T1-T2 breast cancer.
PMCID: PMC5080815  PMID: 27063654
Breast neoplasms; Premenopause; Chemotherapy; Drug therapy; Tamoxifen
10.  Reliability and Validity of Korean Version of Apraxia Screen of TULIA (K-AST) 
Annals of Rehabilitation Medicine  2016;40(5):769-778.
To evaluate the reliability and validity of Korean version of AST (K-AST) as a bedside screening test of apraxia in patients with stroke for early and reliable detection.
AST was translated into Korean, and the translated version received authorization from the author of AST. The performances of K-AST in 26 patients (21 males, 5 females; mean age 65.42±17.31 years) with stroke (23 ischemic, 3 hemorrhagic) were videotaped. To test the reliability and validity of K-AST, the recorded performances were assessed by two physiatrists and two occupational therapists twice at a 1-week interval. The patient performances at admission in Korean version of Mini-Mental State Examination (K-MMSE), self-care and transfer categories of Functional Independence Measure (FIM), and motor praxis area of Loewenstein Occupational Therapy Cognitive Assessment, the second edition (LOTCA-II) were also evaluated. Scores of motor praxis area of LOTCA-II was used to assess the validity of K-AST.
Inter-rater reliabilities were 0.983 (p<0.001) at the first assessment and 0.982 (p<0.001) at the second assessment. For intra-rater (test-retest) reliabilities, the values of four raters were 0.978 (p<0.001), 0.957 (p<0.001), 0.987 (p<0.001), and 0.977 (p<0.001). K-AST showed significant correlation (r=0.758, p<0.001) with motor praxis area of LOTCA-II test. K-AST also showed positive correlations with the total FIM score (r=0.694, p<0.001), the selfcare category of FIM (r=0.705, p<0.001) and the transfer category of FIM (r=653, p<0.001).
K-AST is a reliable and valid test for bedside screening of apraxia.
PMCID: PMC5108703  PMID: 27847706
Apraxias; Upper extremity; Stroke; Reproducibility of results
11.  Effect Modification of Hormonal Therapy by p53 Status in Invasive Breast Cancer 
Journal of Breast Cancer  2013;16(4):386-394.
We aimed to confirm the prognostic and predictive value of p53 expression, particularly in invasive breast cancer patients, according to immunohistochemical hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2) status.
Immunohistochemical data for p53, estrogen receptor, progesterone receptor, and HER2 expression from a total of 15,598 patients were retrospectively retrieved from the web-based database of the Korean Breast Cancer Society. Overall survival (OS) and breast cancer-specific survival (BCSS) were calculated and compared using the Kaplan-Meier method and log-rank test, respectively. Multivariate analyses were performed using a stratified Cox proportional hazard regression model. A model evaluating interactions between p53 expression and both hormonal therapy and chemotherapy was used to determine the treatment benefit from both modalities.
The prognostic value of p53 for OS and BCSS was most significant in the HR+/HER2- subgroup, with hazard ratios of 1.44 (95% confidence interval [CI], 1.08-1.93) and 1.47 (95% CI, 1.09-1.99), respectively. The p53 overexpression hazard ratios were of borderline significance for the HR+/HER2+ subgroup and were not significant for the HR-/HER2+ and HR-/HER2- subgroups. The model with interaction terms revealed that hormonal therapy significantly interacts with p53 status (p=0.002 and p=0.007 for OS and BCSS, respectively), suggesting an insignificant prognostic value for p53 status (p=0.268 and p=0.296 for OS and BCSS, respectively). An interaction between chemotherapy and p53 status was not found in this model.
p53 overexpression has independent prognostic value, particularly in cases of HR+/HER2- invasive breast cancer, which may be due to effect modification of hormonal therapy dependent on p53 status.
PMCID: PMC3893340  PMID: 24454460
Breast neoplasms; Drug resistance; Tumor suppressor protein p53
12.  Induction of Nrf2/ARE-mediated cytoprotective genes by red ginseng oil through ASK1–MKK4/7–JNK and p38 MAPK signaling pathways in HepG2 cells 
Journal of Ginseng Research  2016;40(4):423-430.
The induction of cellular defensive genes such as phase II detoxifying and antioxidant enzymes is a highly effective strategy for protection against carcinogenesis as well as slowing cancer development. Transcription factor Nrf2 (nuclear factor E2-related factor 2) is responsible for activation of phase II enzymes induced by natural chemopreventive compounds.
Red ginseng oil (RGO) was extracted using a supercritical CO2 extraction system and chemical profile of RGO was investigated by GC/MS. Effects of RGO on regulation of the Nrf2/antioxidant response element (ARE) pathway were determined by ARE–luciferase assay, western blotting, and confocal microscopy.
The predominant components of RGO were 9,12-octadecadienoic acid (31.48%), bicyclo[10.1.0]tridec-1-ene (22.54%), and 22,23-dihydrostigmasterol (16.90%). RGO treatment significantly increased nuclear translocation of Nrf2 as well as ARE reporter gene activity, leading to upregulation of heme oxygenase-1 and NAD(P)H:quinone oxidoreductase 1. Phosphorylation of the upstream kinases such as apoptosis signal-regulating kinase (ASK)1, mitogen-activated protein kinase (MAPK) kinase (MKK)4/7, c-Jun N-terminal kinase (JNK), and p38 MAPK were enhanced by treatment with RGO. In addition, RGO-mediated Nrf2 expression and nuclear translocation was attenuated by JNK inhibitor SP600125 and p38 MAPK inhibitor SB202190.
RGO could be used as a potential chemopreventive agent, possibly by induction of Nrf2/ARE-mediated phase II enzymes via ASK1–MKK4/7–JNK and p38 MAPK signaling pathways.
PMCID: PMC5052443  PMID: 27746696
antioxidant response element; cytoprotection; nuclear factor E2-related factor 2; phase II enzyme; red ginseng oil
13.  Identification of ganglioside GM2 activator playing a role in cancer cell migration through proteomic analysis of breast cancer secretomes 
Cancer Science  2016;107(6):828-835.
Cancer cell secretomes are considered a potential source for the discovery of cancer markers. In this study, the secretomes of four breast cancer (BC) cell lines (Hs578T, MCF‐7, MDA‐MB‐231, and SK‐BR‐3) were profiled with liquid chromatography–tandem mass spectrometry analysis. A total of 1410 proteins were identified with less than 1% false discovery rate, of which approximately 55% (796 proteins) were predicted to be secreted from cells. To find BC‐specific proteins among the secreted proteins, data of immunohistochemical staining compiled in the Human Protein Atlas were investigated by comparing the data of BC tissues with those of normal tissues. By applying various criteria, including higher expression level in BC tissues, higher predicted potential of secretion, and sufficient number of tandem mass spectra, 12 biomarker candidate proteins including ganglioside GM2 activator (GM2A) were selected for confirmation. Western blot analysis and ELISA for plasma samples of healthy controls and BC patients revealed elevation of GM2A in BC patients, especially those who were estrogen receptor‐negative. Additionally, siRNA‐mediated knockdown of GM2A in BC cells decreased migration in vitro, whereas the overexpression of GM2A led to an increase in cell migration. Although GM2A as a diagnostic and prognostic marker in BC should be carefully verified further, this study has established the potential role of GM2A in BC progression.
PMCID: PMC4968593  PMID: 27002480
Biomarker; breast cancer; ganglioside GM2 activator; migration; secretome
14.  Tin phosphide-based anodes for sodium-ion batteries: synthesis via solvothermal transformation of Sn metal and phase-dependent Na storage performance 
Scientific Reports  2016;6:26195.
There is a great deal of current interest in the development of rechargeable sodium (Na)-ion batteries (SIBs) for low-cost, large-scale stationary energy storage systems. For the commercial success of this technology, significant progress should be made in developing robust anode (negative electrode) materials with high capacity and long cycle life. Sn-P compounds are considered promising anode materials that have considerable potential to meet the required performance of SIBs, and they have been typically prepared by high-energy mechanical milling. Here, we report Sn-P-based anodes synthesised through solvothermal transformation of Sn metal and their electrochemical Na storage properties. The temperature and time period used for solvothermal treatment play a crucial role in determining the phase, microstructure, and composition of the Sn-P compound and thus its electrochemical performance. The Sn-P compound prepared under an optimised solvothermal condition shows excellent electrochemical performance as an SIB anode, as evidenced by a high reversible capacity of ~560 mAh g−1 at a current density of 100 mA g−1 and cycling stability for 100 cycles. The solvothermal route provides an effective approach to synthesising Sn-P anodes with controlled phases and compositions, thus tailoring their Na storage behaviour.
PMCID: PMC4870634  PMID: 27189834
15.  An elegant route to overcome fundamentally-limited light extraction in AlGaN deep-ultraviolet light-emitting diodes: Preferential outcoupling of strong in-plane emission 
Scientific Reports  2016;6:22537.
While there is an urgent need for semiconductor-based efficient deep ultraviolet (DUV) sources, the efficiency of AlGaN DUV light-emitting diodes (LEDs) remains very low because the extraction of DUV photons is significantly limited by intrinsic material properties of AlGaN. Here, we present an elegant approach based on a DUV LED having multiple mesa stripes whose inclined sidewalls are covered by a MgF2/Al omni-directional mirror to take advantage of the strongly anisotropic transverse-magnetic polarized emission pattern of AlGaN quantum wells. The sidewall-emission-enhanced DUV LED breaks through the fundamental limitations caused by the intrinsic properties of AlGaN, thus shows a remarkable improvement in light extraction as well as operating voltage. Furthermore, an analytic model is developed to understand and precisely estimate the extraction of DUV photons from AlGaN DUV LEDs, and hence to provide promising routes for maximizing the power conversion efficiency.
PMCID: PMC4776099  PMID: 26935402
16.  Carbon- and Binder-Free NiCo2O4 Nanoneedle Array Electrode for Sodium-Ion Batteries: Electrochemical Performance and Insight into Sodium Storage Reaction 
Sodium (Na)-ion batteries (NIBs) have attracted significant interest as an alternative chemistry to lithium (Li)-ion batteries for large-scale stationary energy storage systems. Discovering high-performance anode materials is a great challenge for the commercial success of NIB technology. Transition metal oxides with tailored nanoarchitectures have been considered as promising anodes for NIBs due to their high capacity. Here, we demonstrate the fabrication of a nanostructured oxide-only electrode, i.e., carbon- and binder-free NiCo2O4 nanoneedle array (NCO-NNA), and its feasibility as an anode for NIBs. Furthermore, we provide an in-depth experimental study of the Na storage reaction (sodiation and desodiation) in NCO-NNA. The NCO-NNA electrode is fabricated on a conducting substrate by a hydrothermal method with subsequent heat treatment. When tested in an electrochemical Na half-cell, the NCO-NNA electrode exhibits excellent Na storage capability: a charge capacity as high as 400 mAh g−1 is achieved at a current density of 50 mA g−1. It also shows a greatly improved cycle life (~215 mAh g−1 after 50 cycles) in comparison to a conventional powder-type electrode (~30 mAh g−1). However, the Na storage performance is still inferior to that of Li, which is mainly due to sluggish kinetics of sodiation–desodiation accompanied by severe volume change.
PMCID: PMC4735092  PMID: 26831683
Sodium-ion battery; Nickel-cobalt oxide; Nanoneedle array; Sodium storage; Conversion reaction
17.  The Association between Urine Albumin to Creatinine Ratio and Osteoporosis in Postmenopausal Women with Type 2 Diabetes 
Journal of Bone Metabolism  2016;23(1):1-7.
Osteoporosis is a progressive bone disease that is characterized by a decrease in bone mass density and destruction of microstructure, which can lead to an increased risk of fracture. Although many studies have been published about the relationship between end-stage renal disease and osteoporosis, research on the relationship between proteinuria and the prevalence of osteoporosis is still lacking.
We assessed 91 postmenopausal women with type 2 diabetes who visited our hospital from January 2009 to January 2012.
Among 91 patients, the prevalence of osteoporosis and osteopenia was 35.2% (32 cases) and 32.9% (30 cases) according to bone mineral density. The patients with microalbuminuria and macroalbuminuria (urine albumin-to-creatinine ratio [UACR] ≥ 30) had a significantly higher incidence of osteoporosis compared to subjects with normoalbuminuria (P<0.05).
This study indicates that UACR may be a useful biomarker for increased risk of osteoporosis in postmenopausal women with type 2 diabetes who have been linked to higher UACR levels.
PMCID: PMC4791432  PMID: 26981514
Albumins; Creatinine; Diabetes mellitus type 2; Osteoporosis postmenopausal
18.  Multicenter survey analysis of satisfaction according to actual utilization of rehabilitation services 
[Purpose] Most such studies have been limited to evaluating the muscle activity patterns of lower extremity muscles using surface electromyograms, but studies of muscle activity patterns according to chair types are lacking. [Subjects and Methods] In the present study, 52 university students in their 20s (26 males, 26 females) were selected in order to analyze the activity of five lower extremity muscles (vastus lateralis, rectus femoris, vastus medialis, tibialis anterior, and gastrocnemius). The selected subjects had sufficient muscle strength for the experiment and normal joint range of motion. [Results] To examine the sociodemographic variables of the study subjects, the frequencies and percentages of individual items were presented as follows Table 3. [Conclusion] Differences in lower extremity muscle activity levels during standing and sitting were identified, and differences between genders were also seen. There was no significant difference in lower extremity muscle activity levels between use of fixed and wheeled chairs.
PMCID: PMC4793014  PMID: 27065547
Sit to stand; Electromyograms; Muscle activity
19.  Perceptions of Prophylactic Mastectomy in Korea 
Archives of Plastic Surgery  2016;43(1):53-58.
Increasingly, prophylactic mastectomy has been evaluated as a treatment of breast cancer. Hereditary breast cancer now accounts for approximately 5%–10% of all cases of breast cancer, meaning that the widespread implementation of prophylactic mastectomy may significantly reduce the occurrence of breast cancer. However, prophylactic mastectomy is rarely performed in Korea. Therefore, in this study, we assessed Koreans' attitudes toward and awareness of preventive mastectomy.
This was a prospective study of a cohort of patients attending outpatient clinics and their relatives. Data were collected using self-administered questionnaires assessing sex, age, educational level, knowledge of breast cancer, understanding of prophylactic mastectomy, attitudes toward prophylactic mastectomy, and reasons for choosing prophylactic mastectomy.
Sixty-five patients were included. Most patients (36.9%) were between 40 and 49 years of age and 58.4% were college graduates. Only six respondents (9%) understood prophylactic mastectomy, and 17 respondents (27%) stated that they would agree to undergo prophylactic mastectomy if necessary. Reasons given for refusing prophylactic mastectomy included aesthetic concerns (38%), the perception that it would not cure the disease (26%), possible surgical complications (24%), and financial cost (6%).
In this study, most of the respondents showed a poor knowledge of prophylactic mastectomy. Ultimately, it will be necessary to establish medical guidelines for patients with a high risk of breast cancer, with the objective of providing accurate information and proper treatment at hospitals.
PMCID: PMC4738129  PMID: 26848446
Prophylactic surgical procedures; Breast neoplasms; Mastectomy
20.  Cardiac dose reduction during tangential breast irradiation using deep inspiration breath hold: a dose comparison study based on deformable image registration 
Radiation therapy (RT) for a left-sided breast cancer often involves some incidental exposure of the heart and increase in the rate of major coronary events. One method to reduce the dose to the heart during a tangential breast irradiation is the deep inspiration breath hold (DIBH) technique. Our department adopted DIBH for selected left breast cancer patients with a maximum cardiac distance ≥ 10 mm. We evaluated the effect of the DIBH on cardiac dose compared to normal free breathing (FB). The secondary objective of our present study was to use modeled risk estimates to quantify the risk of coronary events after RT with DIBH.
Methods and materials
Thirty-two patients who underwent RT with DIBH at our hospital were retrospectively analyzed. For each patient, two computed tomography (CT) scans were acquired, FB-CT and DIBH-CT. Using a deformable image registration tool, the target volume was deformed from DIBH-CT to FB-CT, and conventional tangential treatment planning was performed, focusing on the equality of target coverage between the two plans. Doses to the heart, left anterior descending (LAD) artery, and ipsilateral lung were assessed.
By using DIBH, the average mean heart dose was reduced from 724.1 cGy to 279.3 (p < 0.001). The relative heart volume irradiated with 10 Gy–50 Gy was consistently reduced. The mean dose to the LAD coronary artery was reduced from 4079.1 cGy to 2368.9 cGy (p < 0.001). The ipsilateral lung volume receiving 20 Gy or more and 40 Gy or more was reduced by 2.2 % in both cases. Estimated risks of coronary events at 10 years were 4.03 and 2.55 % for RT with FB and DIBH, respectively (p < 0.001).
The use of DIBH during RT of the left-sided breast considerably reduces the doses delivered to the heart and LAD artery with similar target coverage. For the current study patients, the probability of major coronary events was reduced with DIBH.
PMCID: PMC4696108  PMID: 26715382
Breast radiotherapy; Deep inspiration breath hold; Heart dose; Cardiac toxicity; Deformable image registration
21.  Validity and reliability of EQ-5D-3L for breast cancer patients in Korea 
Recently, breast cancer incidence and prevalence has been increasing. Patients' health related quality of life is important considerations in the treatment of breast cancer. The EQ-5D-3L is one of most popular instruments to measure health related quality of life. This study was aimed to evaluate the validity and reliability of EQ-5D-3L in post-operative breast cancer patients from Korea.
A total of 827 patients visiting the ambulatory cancer center of 1 tertiary hospital after breast cancer surgery self-administered the EQ-5D-3L and Functional Assessment of Cancer Therapy-Breast Cancer (FACT-B). We evaluated known-group validity using differences in the EQ-5D-3L index and EQ-VAS score according to demographic and clinical data. The discriminatory ability of the EQ-5D-3L was determined by comparing the mean FACT-B subscale scores between subjects with no problems and subjects with moderate or severe problems in each EQ-5D-3L dimension. Construct validity was evaluated by Pearson correlation coefficients among the EQ-5D-3L index and FACT-B subscales, respectively. Reliability was assessed in terms of test-retest reliability using Cohen’s kappa value and intra-class correlation coefficient (ICC).
The EQ-5D-3L index and EQ-VAS score were higher in the educated, current radiotherapy and unmarried groups. The correlation of EQ-5D-3L index and subscales for the FACT-B was highest in physical well-being (r = 0.553) and lowest in social well-being (r = 0.199). For reliability, the Kappa values’ range was from 0.32 to 0.70, and ICCs of the EQ-5D-3L index and EQ-VAS scores were 0.70 and 0.48, respectively.
This study indicated that the EQ-5D-3L could be a valid health related quality of life instrument for postoperative breast cancer patients.
PMCID: PMC4689040  PMID: 26694964
Breast cancer; EQ-5D-3L; Health-related quality of life; FACT-B; Korea
22.  Concurrent Gonadotropin-Releasing Hormone Agonist Administration with Chemotherapy Improves Neoadjuvant Chemotherapy Responses in Young Premenopausal Breast Cancer Patients 
Journal of Breast Cancer  2015;18(4):365-370.
This study aimed to determine the oncologic efficacy of gonadotropin-releasing hormone (GnRH) agonist treatment concurrent with chemotherapy in a neoadjuvant setting.
A retrospective analysis was performed on 332 cases of invasive breast cancer in patients who were <40 years old at diagnosis and received GnRH agonists concurrent with neoadjuvant chemotherapy (GnRH agonist group) or neoadjuvant chemotherapy alone (neochemotherapy-alone group) from December 2010 to September 2014. Pathologic complete response rates (pCR) and Ki-67 changes were evaluated between the two groups.
Median age was 32±3.9 and 36±3.0 years in the GnRH agonist group and neochemotherapy-alone group, respectively (p<0.001). After adjustment for tumor size, grade, lymph node metastasis, hormone receptor (HR) status, and chemotherapy regimen, the GnRH agonist group exhibited a higher pCR rate with an odds ratio (OR) of 2.98 (95% confidence interval [CI], 1.37-6.34) and a greater decrease in Ki-67 expression after treatment (p=0.05) than the neochemotherapy-alone group. For HR-negative tumors, the GnRH agonist group showed a higher pCR rate (multivariate OR, 3.50; 95% CI, 1.37-8.95) and a greater decrease in Ki-67 expression (p=0.047). For HR-positive breast cancer, the pCR rate, change in Ki-67 index, and clinical response were higher, and preoperative endocrine prognostic index scores were lower, in the GnRH agonist group, but these did not reach statistical significance.
Concurrent administration of GnRH agonists during neoadjuvant chemotherapy improved pCR rates and suppressed Ki-67 expression, especially in HR-negative tumors.
PMCID: PMC4705088  PMID: 26770243
Breast neoplasms; Drug therapy; Gonadotropin-releasing hormone agonist
23.  Extent of Contrast Enhancement on Non-Enhanced Computed Tomography after Intra-Arterial Thrombectomy for Acute Infarction on Anterior Circulation: As a Predictive Value for Malignant Brain Edema 
To determine whether the use of contrast enhancement (especially its extent) predicts malignant brain edema after intra-arterial thrombectomy (IAT) in patients with acute ischemic stroke.
We reviewed the records of patients with acute ischemic stroke who underwent IAT for occlusion of the internal carotid artery or the middle cerebral artery between January 2012 and March 2015. To estimate the extent of contrast enhancement (CE), we used the contrast enhancement area ratio (CEAR)-i.e., the ratio of the CE to the area of the hemisphere, as noted on immediate non-enhanced brain computed tomography (NECT) post-IAT. Patients were categorized into two groups based on the CEAR values being either greater than or less than 0.2.
A total of 39 patients were included. Contrast enhancement was found in 26 patients (66.7%). In this subgroup, the CEAR was greater than 0.2 in 7 patients (18%) and less than 0.2 in the other 19 patients (48.7%). On univariate analysis, both CEAR ≥0.2 and the presence of subarachnoid hemorrhage were significantly associated with progression to malignant brain edema (p<0.001 and p=0.004), but on multivariate analysis, only CEAR ≥0.2 showed a statistically significant association (p=0.019). In the group with CEAR ≥0.2, the time to malignant brain edema was shorter (p=0.039) than in the group with CEAR <0.2. Clinical functional outcomes, based on the modified Rankin scale, were also significantly worse in patients with CEAR ≥0.2 (p=0.003)
The extent of contrast enhancement as noted on NECT scans obtained immediately after IAT could be predictive of malignant brain edema and a poor clinical outcome.
PMCID: PMC4651991  PMID: 26587184
Stroke; Mechanical thrombectomy; Computed tomography; Brain edema
24.  Enlarged Parent Artery Lumen at Aneurysmal-Neck Segment in Wide-Necked Distal Internal Carotid Artery Aneurysms 
Neurointervention  2015;10(2):82-88.
Hypothesizing that the parent artery (PA) diameter of the aneurysm-neck segment is larger than those of normal segments, especially in wide-necked aneurysm cases, we conducted 3D angiographic analyses in wide-necked aneurysm cases focusing on the luminal morphologic change of the PA.
Materials and Methods
Under the approval of local IRB, we enrolled 26 patients with distal internal carotid artery (ICA) aneurysms, which were treated with stent assisted coiling. The PA diameters along the centerline were measured at 6 points with built-in software by two observers. Those 6 points were P1 and P2 proximally, P3 and P4 at the aneurysm ostium margins, and P5 and P6 distally. We performed an ANOVA test and a Bonferroni method for post hoc analyses. Linear regression analysis was performed to find any morphologic influencing factors.
There were 20 distal ICA aneurysms out of 26 consecutive cases after exclusion. The differences in diameter at each point were statistically significant (p<0.0001). On post hoc analyses, the difference between P4 and P5 was significant both in maximum and mean PA diameters (p<0.0001 and p<0.001, respectively). Multivariate analyses failed to reveal any morphological influencing factor.
PAs harboring a wide-necked aneurysm requiring stent assistance for coiling showed significant enlargement of the lumen, especially at the distal transition segment of the aneurysm ostium and the PA.
PMCID: PMC4571558  PMID: 26389011
Cerebral aneurysms; Parent artery; Cerebral angiography; Intracranial stenting; Vascular morphology
25.  Prognostic Factors for Distant Metastasis in Patients with Locoregional Recurrence after Mastectomy 
Journal of Breast Cancer  2015;18(3):279-284.
The purpose of this study was to identify patients with high risk of distant metastasis (DM) after salvage treatment for postmastectomy locoregional recurrence (LRR).
We retrospectively reviewed 142 patients who received salvage radiotherapy with or without wide excision for isolated LRR after mastectomy between January 1999 and December 2012. Distant metastasis-free survival (DMFS) was estimated from the date of diagnosis of isolated LRR to the date of DM or last follow-up using the Kaplan-Meier method, and Cox regression analysis was performed to identify prognostic factors for DM.
The median follow-up period was 54 months. The major failure pattern was DM (56%) and the 5-year DMFS was 43%. In multivariate analysis, initial N (iN) stage, recurrent N (rN) stage, and hormone receptor (HR) status were significant prognostic factors for DM (5-year DMFS: iN0 vs. iN1-3, 73% vs. 25%, p<0.001; rN0 vs. rN1-3, 61% vs. 29%, p<0.001; HR+ vs. HR-, 49% vs. 21%, p<0.001).
Patients with lymph node involvement and/or HR- specimens seem to experience more DM than patients with chest wall-only recurrence and HR+ specimens. Further studies are needed to investigate the role of chemotherapy in these patients.
PMCID: PMC4600693  PMID: 26472979
Breast neoplasms; Drug therapy; Local neoplasm recurrence; Mastectomy; Neoplasm metastasis

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