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"Kim, Yong-Jin"
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Mortality and causes of death in patients with atrial fibrillation: A nationwide population-based study
Patients with atrial fibrillation are known to have a high risk of mortality. There is a paucity of population-based studies about the impact of atrial fibrillation on the mortality risk stratified by age, sex, and detailed causes of death.
A total of 15,411 patients with atrial fibrillation from the Korean National Health Insurance Service-National Sample Cohort were enrolled, and causes of death were identified according to codes of the 10th revision of the International Classification of Diseases.
From 2002 to 2013, a total of 4,479 (29%) deaths were confirmed, and the crude mortality rate for all-cause death was 63.3 per 1,000 patient-years. Patients with atrial fibrillation had a 3.7-fold increased risk of all-cause death compared with the general population. The standardized mortality ratio for all-cause death was the highest in young patients and decreased with increasing age (standardized mortality ratio 21.93, 95% confidence interval 7.60-26.26 in patients aged <20 years; standardized mortality ratio 2.77, 95% confidence interval 2.63-2.91 in patients aged ≥80 years). Women with atrial fibrillation exhibited a greater excess mortality risk than men (standardized mortality ratio 3.81, 95% confidence interval 3.65-3.98 in women; standardized mortality ratio 3.35, 95% confidence interval 3.21-3.48 in men). Cardiovascular disease was the leading cause of death (38.5%), and cerebral infarction was the most common specific disease. Patients with atrial fibrillation had an about 5 times increased risk of death due to cardiovascular disease compared with the general population.
Patients with atrial fibrillation had a 4 times increased risk of mortality compared with the general population. However, the impact of atrial fibrillation on mortality decreased with age and in men. Cerebral infarction was the most common cause of death, and more attention should be paid to reducing the risk of stroke.
Journal Article
Colossal grain growth yields single-crystal metal foils by contact-free annealing
Single-crystal metal foils are valuable for their surface properties that allow for synthesis of materials like graphene. Jin et al. present a strategy for creating colossal single-crystal metal foils called “contact-free annealing” (see the Perspective by Rollett). The method relies on hanging and heating commercially available, inexpensive, cold-rolled metal foils. Almost as if by magic, the polycrystalline grains rotate and anneal into a large single-crystal sheet with a specific crystal orientation. The strategy allows for the creation of much larger and much cheaper single-crystal metal foils. Science , this issue p. 1021 ; see also p. 996 Contact-free annealing allows for the synthesis of large single-crystal metal foils. Single-crystal metals have distinctive properties owing to the absence of grain boundaries and strong anisotropy. Commercial single-crystal metals are usually synthesized by bulk crystal growth or by deposition of thin films onto substrates, and they are expensive and small. We prepared extremely large single-crystal metal foils by “contact-free annealing” from commercial polycrystalline foils. The colossal grain growth (up to 32 square centimeters) is achieved by minimizing contact stresses, resulting in a preferred in-plane and out-of-plane crystal orientation, and is driven by surface energy minimization during the rotation of the crystal lattice followed by “consumption” of neighboring grains. Industrial-scale production of single-crystal metal foils is possible as a result of this discovery.
Journal Article
Electret formation in transition metal oxides by electrochemical amorphization
Transition metal oxides (TMOs) are an important class of materials that show a wide range of functionalities involving spin, charge, and lattice degrees of freedom. The strong correlation between electrons in d-orbitals and the multivalence nature give rise to a variety of exotic electronic states ranging from insulator to superconductor and cause intriguing phase competition phenomena. Despite a burst of research on the multifarious functionalities in TMOs, little attention has been paid to the formation and integration of an electret—a type of quasi-permanent electric field generator useful for nanoscale functional devices as an electric counterpart to permanent magnets. Here, we find that an electret can be created in LaMnO3 thin films by tip-induced electric fields, with a considerable surface height change, via solid-state electrochemical amorphization. The surface charge density of the formed electret area reaches ~400 nC cm−2 and persists without significant charge reduction for more than a year. The temporal evolution of the surface height, charge density, and electric potential are systematically examined by scanning probe microscopy. The underlying mechanism is theoretically analyzed based on a drift-diffusion-reaction model, suggesting that positively charged particles, which are likely protons produced by the dissociation of water, play crucial roles as trapped charges and a catalysis to trigger amorphization. Our finding opens a new horizon for multifunctional TMOs.Electric materials: Finding a sense of permanenceA material that generates its own electric field has been developed by scientists in South Korea. An electret is the electrical equivalent of a magnet in that it is formed of two electric poles rather than two magnetic poles. Just as magnetic dipoles give rise to permanent magnets, electret materials create a quasi-permanent electric field. They are useful for microphones, photocopiers and many other electrical devices. Yong-Jin Kim and Chan-Ho Yang from the Korea Advanced Institute of Science and Technology, Daejeon, have created an electret using transition metal oxides. The researchers used a sharp tip of platinum-coated silicon to “write” a charged pattern with a density similar to that of commercially available electrets into a thin film of lanthanum manganite. These patterns persisted for more than a year.
Journal Article
Early Surgery versus Conventional Treatment for Infective Endocarditis
The timing of surgery in the context of acute endocarditis associated with valvular failure and large vegetations is controversial. In this randomized trial in South Korea, early surgery was associated with fewer clinically significant embolic events than conventional treatment.
Despite advances in medical and surgical treatment, infective endocarditis remains a serious disease that carries a considerable risk of death and morbidity.
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The role of surgery in the treatment of infective endocarditis has been expanding, and current guidelines advocate surgical management for complicated left-sided infective endocarditis.
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Early surgery is strongly indicated for patients with infective endocarditis and congestive heart failure,
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but the indications for surgical intervention to prevent systemic embolism remain to be defined.
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Early identification of patients with large vegetations and a high risk of embolism,
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increased experience with complete excision of infected tissue and valve . . .
Journal Article
Physical mechanisms for the dominant summertime high-latitude atmospheric teleconnection pattern and the related Northern Eurasian climates
Summertime atmospheric teleconnection patterns over Eurasia have a significant influence on regional weather and climate. Despite extensive studies on the subtropical patterns, the high-latitude counterpart has received relatively less attention. This study proposes physical mechanisms for the formation and maintenance of the dominant high-latitude teleconnection pattern. The formation of the pattern is associated with variability in synoptic-scale eddy activity due to the meridional gradient of sea surface temperature anomalies in the vicinity of the Gulf Stream, causing a meridional shift of the central axis of storm track at the exit of Atlantic jet. The resultant convergence of transient vorticity fluxes to the west of the British Isles induces low-frequency cyclonic circulation anomalies and continued propagation of Rossby waves downstream along northern Eurasia. Once these circulation anomalies are formed, the subsequent latent heat-related diabatic anomalies over the northern Eurasian landmass act as another source of Rossby waves to maintain the teleconnection pattern. Regional temperature and precipitation variability is closely linked to the wave pattern along a route through northern Eurasia, and even precipitation over the East Asian summer monsoon region is influenced by the teleconnection pattern.
Journal Article
Risk of ischemic stroke in metabolically healthy obesity: A nationwide population-based study
Whether metabolically healthy obese (MHO) individuals are at increased risk of ischemic stroke is not well known. We investigated the association of the MHO phenotype with ischemic stroke.
A total of 354,083 adults (age 45.8 ± 14.2 years) from the Korean National Health Insurance Service-National Sample Cohort enrolled in 2004-2008 were followed-up for incident ischemic stroke until 2013. Subjects meeting none of the metabolic syndrome criteria were classified as 'metabolically healthy'. The cohort was categorized into four groups according to obesity and metabolic status: metabolically healthy normal weight (MHNW), metabolically unhealthy normal weight (MUNW), MHO, and metabolically unhealthy obese (MUO).
Ischemic stroke was newly diagnosed in 4,884 (1.4%) individuals during a mean follow-up of 7.4 ± 1.5 years. Stroke incidence rates for the MHNW, MUNW, MHO, and MUO groups were 0.56, 2.61, 0.61, and 2.76 per 1,000 person-years, respectively. While risk for stroke increased significantly in metabolically unhealthy groups, it was not increased in MHO compared to the MHNW group on multivariate analysis. In metabolically healthy individuals, obesity did not increase the risk for ischemic stroke, regardless of the severity of obesity. Meanwhile, in metabolically unhealthy individuals, being obese was significantly associated with increased risk of stroke.
MHO individuals were not at increased risk for ischemic stroke. However, obesity increased risk for ischemic stroke in persons with metabolic risk factors; therefore, maintaining normal weight may be more important for this population. Also, metabolic unhealthiness showed greater association than obesity with stroke.
Journal Article
Trends of the prevalence and incidence of hypertrophic cardiomyopathy in Korea: A nationwide population-based cohort study
Temporal trends of the prevalence and incidence of hypertrophic cardiomyopathy (HCM) have not been well established in Asian populations. Using the Korean National Health Insurance Services database, we identified patients with a confirmed diagnosis of HCM between 2010 and 2016. The annual prevalence and incidence of HCM, and their clinical characteristics were investigated. The prevalence of HCM has increased from 0.016% (n = 6313) in 2010 to 0.031% (n = 13,035) in 2016. During a 7-year period, 13,229 patients were newly diagnosed with HCM. The incidence rate increased from 4.15 (per 100,000 person-years) in 2010 to 5.6 in 2016. The prevalence and incidence of HCM increased with age and peaked during the 70s, with male predominance in all age groups. Chest pain is the most frequent clinical presentation followed by shortness of breath and syncope. Hypertension and dyslipidemia were the two most common comorbidities. Heart failure and atrial fibrillation was diagnosed in about 1/3 and 1/4 of patients with HCM, respectively. The prevalence and incidence of HCM gradually increased from 2010 to 2016, possibly due to heightened recognition of the disease. Given the progressively high incidence of HCM with age and high prevalence of coexisting modifiable risk factors, continued efforts are required to increase awareness regarding HCM-related symptoms and potential complications.
Journal Article
Dehydroabietic Acid Suppresses Inflammatory Response Via Suppression of Src-, Syk-, and TAK1-Mediated Pathways
Dehydroabietic acid (DAA) is a naturally occurring diterpene resin acid derived from coniferous plants such as Pinus and Picea. Various bioactive effects of DAA have been studied including antibacterial, antifungal, and anticancer activities. However, the anti-inflammatory mechanism of DAA remains unclear. We evaluated the anti-inflammatory effect of DAA in macrophage cell lines. Dehydroabietic acid clearly reduced nitric oxide (NO) production and inflammatory gene expression decreased according to RT-PCR results. Dehydroabietic acid displayed anti-inflammatory activity at the transcriptional level in results from NF-κB- or AP-1-mediated luciferase assays. To identify the DAA target protein, we investigated NF-κB and AP-1 pathways by Western blotting analysis. Dehydroabietic acid suppressed the activity of proto-oncogene tyrosine protein kinase (Src) and spleen tyrosine kinase (Syk) in the NF-κB cascade and transforming growth factor beta-activated kinase 1 (TAK1) in the AP-1 cascade. Using overexpression strategies, we confirmed that DAA targeted these kinases. Our findings demonstrate the anti-inflammatory effects and molecular mechanism of DAA. This suggests that DAA has potential as a drug or supplement to ameliorate inflammation.
Journal Article
Growth dynamics and gas transport mechanism of nanobubbles in graphene liquid cells
Formation, evolution and vanishing of bubbles are common phenomena in nature, which can be easily observed in boiling or falling water, carbonated drinks, gas-forming electrochemical reactions and so on. However, the morphology and the growth dynamics of the bubbles at nanoscale have not been fully investigated owing to the lack of proper imaging tools that can visualize nanoscale objects in the liquid phase. Here, we demonstrate for the first time that the nanobubbles in water encapsulated by graphene membrane can be visualized by
in-situ
ultra-high vacuum transmission electron microscopy. Our microscopic results indicate two distinct growth mechanisms of merging nanobubbles and the existence of a critical radius of nanobubbles that determines the unusually long stability of nanobubbles. Interestingly, the gas transport through ultrathin water membranes at nanobubble interface is free from dissolution, which is clearly different from conventional gas transport that includes condensation, transmission and evaporation.
Nanobubbles in liquid phase are puzzling, because their internal pressure is estimated to be unphysically large. Here, Shin
et al
. visualize the dynamics of nanobubbles in water encapsulated by graphene membrane and show fast gas diffusion through ultrathin water layer between two coalescing bubbles.
Journal Article