Publications by authors named "Choi R"

AlGaN-based vertical type high power ultraviolet-C light emitting diodes (UV-C LEDs), which have a Ga-face n-contact structure, were fabricated on a LED epilayer transferred to a carrier wafer through a laser lift-off (LLO) process. A significant light extraction enhancement of the vertical chip by using a highly reflective ITO/Al p-type electrode is demonstrated, along with surface roughening. A GaN-free LED epi structure is employed to prevent light absorption in the UV-C wavelength region.

View Article and Find Full Text PDF

Objective: Conventional risk stratification models for mortality of acute myocardial infarction (AMI) have potential limitations. This study aimed to develop and validate deep-learning-based risk stratification for the mortality of patients with AMI (DAMI).

Methods: The data of 22,875 AMI patients from the Korean working group of the myocardial infarction (KorMI) registry were exclusively divided into 12,152 derivation data of 36 hospitals and 10,723 validation data of 23 hospitals.

View Article and Find Full Text PDF

Glioblastoma (GBM) is a disease without any definite cure. Numerous approaches have been tested in efforts to conquer this brain disease, but patients invariably experience recurrence or develop resistance to treatment. New surgical tools, carefully chosen samples, and experimental methods are enabling discoveries at single-cell resolution.

View Article and Find Full Text PDF

Background: Hepatitis B virus (HBV) infection remains a global concern with different epidemiologies due to several factors including migration, vaccination policies, and new antiviral treatment regimens. It is important to understand the characteristics of a patient population, including the prevalence of diseases, and to assess test utilization to understand and evaluate the clinical performance of laboratory tests and to improve the quality of clinical laboratories.

Materials And Methods: In this study, we evaluated serologic and virologic laboratory tests including hepatitis B surface antigen, hepatitis B surface antibody, hepatitis B envelope antigen (HBeAg), hepatitis B envelope antibody, and HBV DNA in Korean adults who were exposed to HBV.

View Article and Find Full Text PDF

Background: There have been little data about outcomes of percutaneous coronary intervention (PCI) for in-stent restenosis (ISR) chronic total occlusion (CTO) in the drug eluting stent (DES) era. This study aimed to compare the procedural success rate and long-term clinical outcomes of ISR CTO and de novo CTO.

Methods And Results: Patients who underwent PCI for ISR CTO (n = 164) versus de novo CTO (n = 1208) were enrolled from three centers in Korea between January 2008 and December 2014.

View Article and Find Full Text PDF

AMP-activated protein kinase (AMPK) is a member of Ser/Thr kinases that has been shown to regulate energy balance. Although recent studies have demonstrated the function of AMPK in adipose tissue using different fat-specific AMPK knockout mouse models, the results were somewhat inconsistent. For this study, we tested the hypothesis that AMPK in adipose tissue regulates whole body glucose metabolism.

View Article and Find Full Text PDF
Article Synopsis
  • Shigella spp. are major causes of diarrhea in children, and rising antibiotic resistance highlights the urgent need for new treatments.
  • A new bioluminescent strain of S. flexneri (S. flexneri lux1) was developed to test antibiotic effectiveness in both cell culture and mouse models.
  • Ciprofloxacin and ampicillin were shown to significantly reduce Shigella infection in treated mice, but the effectiveness of these antibiotics couldn't be differentiated by radiance data, suggesting these models could streamline the search for new antibiotics.
View Article and Find Full Text PDF

A bioinspired neuromorphic device operating as synapse and neuron simultaneously, which is fabricated on an electrolyte based on Cu-doped salmon deoxyribonucleic acid (S-DNA) is reported. Owing to the slow Cu diffusion through the base pairing sites in the S-DNA electrolyte, the synaptic operation of the S-DNA device features special long-term plasticity with negative and positive nonlinearity values for potentiation and depression (α and α), respectively, which consequently improves the learning/recognition efficiency of S-DNA-based neural networks. Furthermore, the representative neuronal operation, "integrate-and-fire," is successfully emulated in this device by adjusting the duration time of the input voltage stimulus.

View Article and Find Full Text PDF

Wnt signaling plays a major role in bone metabolism. Advances in our understanding of secreted regulators of Wnt have yielded several therapeutic targets to stimulate osteoanabolism-the most promising of which is the Wnt inhibitor sclerostin. Sclerostin antibody recently gained approval for clinical use to treat osteoporosis, but the biology surrounding sclerostin antagonism is still incompletely understood.

View Article and Find Full Text PDF

Tendons with different in vivo functions are known to have different baseline biomechanics, biochemistry and ultrastructure, and these can be affected by changes in loading. However it is not know whether different tendon types respond in the same, or different ways, to changes in loading. This study performed in vitro un-loading (stress deprivation) in culture on ovine medial extensor tendons (MET, a positional tendon), and superficial and deep digital flexor tendons (SDFTs and DDFTs, with energy-storing and intermediate functions respectively), for 21 days (n = 14 each).

View Article and Find Full Text PDF

: Gastric cancer (GC) is the fifth most common cancer and confers the second-highest mortality among other cancers. Improving the survival rates of GC patients requires prompt and accurate diagnosis and effective treatment which is often preceded by the poorly understood pathogenic mechanisms. : This literature review aims to summarize current understanding of genetic and molecular alterations that promote carcinogenesis including (1) activation of oncogenes, (2) overexpression of growth factors, receptors and matrix metalloproteinases, (3) inactivation of tumor suppressor genes, DNA repair genes, and cell adhesion molecules and (4) alterations of cell-cycle regulators that regulate biological characteristics of cancer cells.

View Article and Find Full Text PDF

Purpose: The current status of therapeutic drug monitoring (TDM) assay utilization by clinical laboratories in South Korea remains little known. We investigated the TDM status of five antibiotics known for nephrotoxicity (vancomycin, amikacin, gentamicin, tobramycin, and teicoplanin) for the improvement of TDM in South Korea among patients with infectious diseases using a cross-sectional nationwide survey.

Patients And Methods: We developed an online questionnaire and collected responses using a user-friendly web-based platform.

View Article and Find Full Text PDF

Background: The frequency of using veno-arterial extracorporeal membrane oxygenation increased, especially in patients with refractory cardiogenic shock or cardiac arrest. However, data of complications of veno-arterial extracorporeal membrane oxygenation are lacking. This study sought to investigate the incidence of veno-arterial extracorporeal membrane oxygenation complications for acute myocardial infarction patients with refractory cardiogenic shock or cardiac arrest and its relationship with patient survival.

View Article and Find Full Text PDF

This study investigated the effects and mechanism of Heshouwu ( Thunb.) water extract (HSW) on diabetes-related bone loss in mice. HSW was orally administered (300 mg/kg body weight) to high-fat diet and streptozotocin-induced diabetic mice for 10 weeks.

View Article and Find Full Text PDF

Background: The objective of this study was to analyze the expenditures on medical expenses and its determinants using the Korean Retirement and Income Data conducted by the National Pension Research Institute.

Methods: This study utilized data from the Korean Retirement and Income Study from 2005 to 2013, which were compiled by the National Pension Research Institute. The t test and ANOVA were used to analyze the general characteristics and medical expenditures of subjects depending on the receipt of public pension, and logistic regression was used to identify the determinants of medical expenditures.

View Article and Find Full Text PDF

Background: Damage to olfactory sensory neurons (OSNs), situated within the neuroepithelium of the olfactory cleft, may be associated with anosmia. Although their direct contact with the nasal airspace make OSNs vulnerable to injury and death, multiple mechanisms maintain epithelium integrity and olfactory function. We hypothesized that BMI1, a polycomb protein found to be enriched in OSNs, may function in neuroprotection.

View Article and Find Full Text PDF

Recent studies have illustrated the burden Cryptosporidium infection places on the lives of malnourished children and immunocompromised individuals. Treatment options remain limited, and efforts to develop a new therapeutic are currently underway. However, there are unresolved questions about the ideal pharmacokinetic characteristics of new anti-Cryptosporidium therapeutics.

View Article and Find Full Text PDF

Background And Objectives: This study aimed to confirm the effects of traditional holidays on the incidence and outcomes of out-of-hospital cardiac arrest (OHCA) in South Korea.

Methods: We studied 95,066 OHCAs of cardiac cause from a nationwide, prospective study from the Korea OHCA Registry from January 2012 to December 2016. We compared the incidence of OHCA, in-hospital mortality, and neurologic outcomes between traditional holidays, Seollal (Lunar New Year's Day) and Chuseok (Korean Thanksgiving Day), and other day types (weekday, weekend, and public holiday).

View Article and Find Full Text PDF

Stem cell-based therapies have been proposed as a strategy to replace damaged tissues, especially in the nervous system. A primary sensory modality, olfaction, is impaired in 12% of the US population, but lacks treatment options. We report here the development of a novel mouse model of inducible hyposmia and demonstrate that purified tissue-specific stem cells delivered intranasally engraft to produce olfactory neurons, achieving recovery of function.

View Article and Find Full Text PDF

Gentiopicroside is a major active component of the Gentiana scabra Bge., which is commonly used as herbal medicine for the treatment of inflammation in Asia. Gentiopicroside significantly down-regulated expression of key adipogenic transcription factors (PPARγ, C/EBPα, SREBP-1c) and dose-dependently inhibited the lipid uptake-related gene (LPL), fatty acid transport-related gene (FABP4) and triglyceride (TG) synthesis-related gene (DGAT2), as well as fatty acid synthesis-related genes (FAS, SCD1), which resulted in reduced intracellular lipid droplet accumulation and TG content in 3T3-L1 cells.

View Article and Find Full Text PDF

Most studies on gender difference of the in-hospital outcome of percutaneous coronary intervention (PCI) were performed in the pre-drug-eluting stents (DES) era. This study was performed to investigate whether gender influences the in-hospital outcome of PCI in the DES era.A total of 44,967 PCI procedure between January and December of 2014 from the nationwide PCI registry database in Korea were analyzed.

View Article and Find Full Text PDF

Background And Objectives: Screening and early diagnosis for heart failure (HF) are critical. However, conventional screening diagnostic methods have limitations, and electrocardiography (ECG)-based HF identification may be helpful. This study aimed to develop and validate a deep-learning algorithm for ECG-based HF identification (DEHF).

View Article and Find Full Text PDF

Previous studies on drug efficacy showed low protection against abortion and vertical transmission of in pregnant sheep. Bumped kinase inhibitors (BKIs), which are ATP-competitive inhibitors of calcium-dependent protein kinase 1 (CDPK1), were shown to be highly efficacious against several apicomplexan parasites and in laboratory animal models. Here, we present the safety and efficacy of BKI-1294 treatment (dosed orally at 100 mg/kg of body weight 5 times every 48 h) initiated 48 h after oral infection of sheep at midpregnancy with 1,000 TgShSp1 oocysts.

View Article and Find Full Text PDF

There exists controversy on whether and for how long anticoagulation is necessary after primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI).We aimed to study the impact of prolonged (>24 h) or brief (<24 h) postprocedural anticoagulation on infarct size assessed by cardiac magnetic resonance (CMR) after 30 days as well as on left ventricular ejection fraction (LVEF) and left ventricular (LV) remodeling evaluated by 2D-echocardiography after 9 months from the INNOVATION trial (Clinical Trial Registration: NCT02324348).Of the 114 patients (mean age: 59.

View Article and Find Full Text PDF

Nickel silicide (NiSi) is commonly used as a contact material for metal junctions but the poor thermal instability of NiSi above 600 °C has limited the further scaling down of devices and the implementation of novel schemes, such as monolithic 3-dimensional integration. This paper suggests a process to improve the thermal stability of NiSi through nitrogen incorporation during the silicidation process. The optimal level of nitrogen incorporation in NiSi reduced the nickel diffusion rate and enhanced the thermal stability by preventing the formation of a nickel disilicide phase.

View Article and Find Full Text PDF