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Aims Previous in-vitro and in-vivo experimental studies have shown that Sestrin2 attenuates oxidative stress and the pro-inflammatory pathway, resulting in improving metabolic homeostasis. However, the relationship between circulating Sestrin2 concentration and cardiometabolic risks in humans has not been explored. Methods Sestrin2 concentration was measured in 240 subjects (46 without diabetes and 194 with diabetes), and the associations between Sestrin2 level and various cardiometabolic risk factors including body composition, insulin resistance, and atherosclerosis was assessed. Results Sestrin2 concentration showed a trend of increasing in subjects with metabolic syndrome. After adjustment for age and gender, Sestrin2 level had a positive relationship with serum triglyceride, alanine aminotransferase (ALT), and creatinine levels, but no association with carotid atherosclerosis. Especially, in subjects with type 2 diabetes Sestrin2 concentration exhibited a significant positive correlation with body mass index (P = 0.015), waist circumference (P = 0.020), high-sensitivity C-reactive protein (P = 0.008), Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) (P = 0.041), percentage body fat (P = 0.001), and truncal fat mass (P = 0.005) after adjusting age and gender. Multiple stepwise regression analysis identified age, serum ALT and creatinine levels, and percentage body fat as independent determining factors for Sestrin2 concentration in patients with type 2 diabetes (R2 = 0.173). Conclusions This study is the first to demonstrate a trend for increased Sestrin2 level in subjects with metabolic syndrome. In particular, in subjects with type 2 diabetes, Sestrin2 was significantly related to insulin resistance and percentage body fat, suggesting its potential as a novel modulatory factor for metabolic disorders in humans.

Although statin use in patients with acute myocardial infarction (AMI) is mandatory, it has been suggested to be associated with new-onset diabetes mellitus (NODM). In real world practice, moderate-intensity statin therapy is more commonly used than high-intensity statin therapy. In this study, we investigated the impact of moderate-intensity pitavastatin (2 to 4 mg) compared with moderate-intensity atorvastatin (10 to 20 mg) and rosuvastatin (5 to 10 mg) on the development of NODM during a follow-up period of up to 3years. Between November 2011 and May 2015, 2001 patients with AMI who did not have diabetes mellitus were investigated. The cumulative incidence of NODM was evaluated in all groups. To adjust for potential confounders, multinomial propensity scores were used. Cox proportional hazard models were used to assess the hazard ratio of NODM in the atorvastatin and rosuvastatin groups compared with pitavastatin group. The cumulative incidence of NODM was significantly lower in pitavastatin group compared with the atorvastatin and rosuvastatin groups (3.0% vs 8.4% vs 10.4%, respectively; Log-rank p value = 0.001). After weighting the baseline characteristics of the 3 statin groups by multinomial propensity scores, atorvastatin (hazard ratio: 2.615, 95% confidence interval: 1.163 to 5.879) and rosuvastatin (hazard ratio: 3.906, 95% confidence interval: 1.756 to 8.688) were found to be associated with a higher incidence of NODM compared with pitavastatin therapy on multivariable analysis. Moderate-intensity pitavastatin therapy is associated with a lower incidence of NODM in patients with AMI andhas similar clinical outcomes to moderate-intensity atorvastatin and rosuvastatin therapy.

Objectives Aseptic bone flap resorption (ABFR) is a known complication of cranioplasty (CP) with an autologous bone flap. The incidence of ABFR has been reported to be as high as 34.2% in the literature; however, it is underestimated in clinical fields. We retrospectively reviewed 13 years of clinical cases of patients who underwent CP after decompressive craniectomy (DC) to investigate the incidence and risk factors of ABFR. Methods Ninety-one patients who underwent DC and CP in Guro Hospital, Korea University Medical Center, were enrolled. ABFR was defined using serial brain computed tomography. To identify possible risk factors for ABFR, univariate and multivariate Cox regression and receiver operating characteristic curve analyses were performed. Results Of the 91 patients enrolled, ABFR was diagnosed in 32 patients (35.1%). Bone flap size, existence of a shunting system, and the DC-CP interval were significant in the univariate analysis. Bone flap size was statistically significant in the multivariate analysis (P = 0.0189). The cutoff points of the DC-CP interval and bone flap size were 44 days and 110 cm2, respectively. Conclusions The incidence of ABFR was remarkably high. Bone flap size, the existence of a shunting system, and the DC-CP interval were shown to be potential risk factors of ABFR after CP.

Background Growing evidence suggests that non-alcoholic fatty liver disease (NAFLD) is associated with cardiovascular disease as well as metabolic syndrome. FDG-PET is a novel imaging technique that detects vascular inflammation, which may reflect rupture-prone vulnerable atherosclerotic plaques. Methods Vascular inflammation was measured as the maximum target-to-background ratio (maxTBR), along with various cardiometabolic risk factors in 51 subjects with NAFLD, and compared with 100 age- and gender-matched subjects without NAFLD. The liver attenuation index (LAI), which was measured using computed tomography, was used as a parameter for the diagnosis of NAFLD. Results After adjusting for age and sex, both maxTBR and LAI values were associated with several cardiometabolic risk parameters. Furthermore, there was a significant inter-relationship between LAI and maxTBR values ( r = − 0.227, P = 0.005). Individuals with NAFLD had higher maxTBR values than those without NAFLD ( P = 0.026), although their carotid intima–media thickness (CIMT) values did not differ. The proportion of subjects with NAFLD showed a step-wise increment following the tertiles of maxTBR values ( P for trend = 0.015). In multiple logistic regression analysis, maxTBR tertiles were independently associated with NAFLD after adjusting for age, gender, systolic blood pressure, triglycerides, HDL-cholesterol, glucose, BUN, creatinine and homeostasis model assessment of insulin resistance (HOMA-IR) ( P = 0.030). However, their relationship was attenuated after further adjustment for waist circumference or high sensitive C-reactive protein. Conclusion Patients with NAFLD have an increased risk for vascular inflammation as measured via FDG-PET/CT even without difference in CIMT. (Clinical trials No. NCT01958411 , http://www.clinicaltrials.gov /)

A new pooled cohort risk equation to estimate atherosclerotic cardiovascular disease (CVD) risk was recently published, but the equation is based primarily on data from Caucasian populations. The relationship of this new risk scoring system with vascular inflammation and calcification has yet to be examined.A total of 74 participants were retrospectively selected based on inclusion and exclusion criteria. All participants underwent (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) and multi-detector computed tomography (MDCT) examination in the Korea University Guro Hospital between June 2009 and May 2013. Vascular inflammation of the carotid artery was measured as target-to-background ratio (TBR) using (18)F-FDG-PET/CT and coronary artery calcification was quantified as Agatston score by MDCT.Agatston scores were not significantly associated with any metabolic risk factors, but maximum TBR values exhibited a significant positive correlation with body mass index (r=0.31, P=0.01), waist circumference (r=0.42, P0.01), waist-to-hip ratio (r=0.49, P0.01), and systolic (r=0.35, P0.01) and diastolic blood pressure (r=0.39, P0.01). Furthermore, maximum TBR values were significantly correlated with serum high-sensitivity C-reactive protein (hsCRP) levels (r=0.26, P=0.03), whereas Agatston scores had no correlation. When pooled cohort risk equation scores were divided into incremental tertiles, age, waist circumference, waist-to-hip ratio and systolic blood pressure showed significant incremental trends. In particular, pooled cohort risk scores exhibited a significant positive correlation with maximum TBR values (r=0.35, P0.01), but not with Agatston scores (r=0.11, P=0.34).The pooled cohort risk equation exhibited significant positive correlations with vascular inflammation but not with calcification in Asian subjects without CVD, suggesting that this novel risk equation may detect early inflammatory changes preceding the structural modification of vessel walls.

Background: Anemia is a major risk factor that contributes to mortality in patients with chronic kidney disease. There is controversy over the optimal hemoglobin (Hb) target in these patients. This study investigated the association between Hb level and mortality in a cohort of hemodialysis (HD) patients in Korea. Methods: This study was a multicenter prospective observational study of maintenance HD patients that was performed for 5 years in western Seoul, Korea. Three hundred and sixty-two participants were enrolled. Laboratory values and mortality were accessed every 6 months. Repeated measures of laboratory values in each interval were averaged to obtain one semiannual mean value. The Hb values were divided into six groups: (1) Hb

Recent studies have suggested that body size phenotype may contribute to atherosclerosis and cardiovascular disease. 18 F-fluorodeoxyglucose (FDG) positron emission tomography is a useful imaging technique for detecting vascular inflammation that may reflect plaque vulnerability. Therefore, we analyzed which body size phenotypes cause the increased vascular inflammation using FDG positron emission tomography. We compared 18 F-FDG uptake, measured using the blood-normalized standardized uptake value, known as the target-to-background ratio (TBR), along with various cardiometabolic risk parameters in 250 participants without a history of cardiovascular disease. Body size phenotypes were classified according to body mass index and the presence/absence of metabolic syndrome. Cardiometabolic risk factors were significantly different among the body size phenotype groups. In particular, the maximum TBR (maxTBR) values in the metabolically abnormal but normal-weight, metabolically healthy obese (MHO), and metabolically abnormal obese groups were significantly greater than those of the metabolically healthy normal-weight (MHNW) group. Components of metabolic syndrome, insulin resistance, high-sensitivity C-reactive protein, and Framingham Risk Score were associated with maxTBR value. Interestingly, although the Framingham Risk Score of the MHO group was almost similar to that of the MHNW group, maxTBR value of MHO subjects was significantly higher than that of MHNW subjects (1.38 [1.20, 1.50] vs 1.22 [1.12, 1.37], p = 0.006). In conclusion, the present study suggests that unique subsets of body size phenotype, such as MHO or metabolically abnormal but normal weight, may have distinct effects on vascular inflammation.

Background The receptor for advanced glycation end-products (RAGE) and its diverse ligands play a pivotal role in the development of cardiovascular disease. Soluble forms of RAGE (sRAGE), including the splice variant endogenous secretory RAGE (esRAGE), may neutralize AGE-RAGE mediated vascular damage by acting as a decoy. 18 F-fluorodeoxyglucose positron emission tomography (FDG-PET) is a novel imaging technique for detecting vascular inflammation. Methods We examined vascular inflammation measured using FDG-PET in 41 type 2 diabetes patients and 41 healthy control subjects in the right carotid artery. Vascular 18 F-FDG uptake was measured as the blood-normalized standardized uptake value (SUV), known as the target-to-background ratio (TBR). In addition, their relationship with carotid intima-media thickness (CIMT), estimated GFR (eGFR), and other cardiovascular risk factors was evaluated. Results Both mean and maximum TBR values were significantly higher in patients with type 2 diabetes compared to healthy subjects. After adjusting for age and gender, sRAGE levels were significantly correlated with both mean and maximum TBR values, but not with CIMT values. Multiple linear regression analysis showed that maximum TBR values were independently associated with sRAGE levels in addition to HbA1c and eGFR. Conclusions Circulating sRAGE showed significant association with TBR values measured using FDG-PET, which reflect vascular inflammation.

Micron-sized WC-Co powder (powder) was coated onto an 420J2 steel substrate and the bond coats (BCs) of Ni, NiCr, and Ni/NiCr using high-velocity oxy-fuel thermal spraying to study the surface properties, friction behavior, and tensile bond strength of the WC-Co coating (WC-Co) on the 420J2 substrate (sub) and the BCs of Ni, NiCr, and Ni/NiCr. During the spray coating, a small portion of WC decomposed to the less-hard W 2 C, W, and free carbon above its decomposition temperature of 1250 °C, decreasing hardness and increasing porosity. The surface hardness of 1120 ± 100 Hv (10,980 ± 980 MPa) depended strongly on the spray parameters. It was three to four times harder than metals and alloys, but less than one-half the hardness of binder-less pure WC (2400 Hv). Free carbon reacted with the sprayed oxygen gas and formed carbon oxide gases, resulting in a coating of 4.3 ± 1.0% porosity. The friction coefficient of the coating increased about 17% with increasing surface temperature: 0.65 ± 0.03 at 25 °C to 0.76 ± 0.06 at 500 °C because of the increased local cold-welding of the asperities at the higher temperature of 500 °C. Sub/WC-Co, sub/Ni/WC-Co, sub/NiCr/WC-Co, and sub/Ni/NiCr/WC-Co had tensile bond strengths of 9600 ± 300 psi (66.2 ± 3.4 MPa), 6300 ± 200 psi, 6000 ± 200 psi, and 7500 ± 200 psi, respectively. The fracture locations of all coatings were at interfaces with the WC-Co coating, indicating that the adhesion of the WC/Co inside coating was higher than 9600 ± 500 psi and that the adhesion of WC-Co on the substrate (9600 ± 500 psi) was much higher than the adhesion on the BCs.

Nanostructured thermal spray coatings have been intensively studied because of their potential in a wide variety of industrial applications. In the present paper, current development status of nanostructured thermal spray coatings is presented, mainly based on the results of the authors. In the nanostructured WC–Co wear-resistant coatings, the influence of feedstock characteristics on the coating properties was discussed to suggest the desirable morphology of feedstock for thermal spraying. For the nanostructured Cr2O3 based solid-lubricant coatings, the advanced feedstock has been developed in order to solve the inhomogeneity problem of the conventional coatings. Various properties of the nanostructured coatings were evaluated and compared with those of the conventional counterparts. These results clearly demonstrate that the significant improvement in coating performance can be achieved by utilizing proper nanostructured coatings.

A conventional micro-sized NiCr–Cr 2 O 3 –Ag–BaF 2 /CaF 2 blending feedstock (PS304; developed by NASA) leads to a non-uniform layered coating microstructure due to the difference in the physical and thermophysical properties of components. Therefore, in this research, we made a new feedstock of one system including a nano-component (under 100 nm Cr 2 O 3 ) through the spray drying method. Microstructure and mechanical properties of the nano-Cr 2 O 3 containing spray-dried coatings were evaluated and compared with the blended feedstock (PS304). The coating microstructure had more uniform, finer microstructure and the mechanical properties (Vickers microhardness and bonding strength) of spray-dried coatings were improved.

A series of the electrochemical and long-term immersion tests was carried out in a strong sulfuric acid (5 wt.% H2SO4) solution on thermal sprayed WC cermet coatings having various kinds of metallic binder in order to examine the effect of composition of binder materials on the corrosion behavior. In the present study, the coatings were processed via a high velocity oxygen fuel (HVOF) spraying technique with WC–Co, WC–Co–Cr, WC–CrC–Ni and WC–Ni composite powders. The experimental results revealed that a considerable galvanic corrosion occurred between WC particles and metallic binders in the aerated 5 wt.% H2SO4 solution. The corrosion resistance of the coatings containing Cr was better than that of the coatings without Cr. For the coatings without Cr, general corrosion occurred in binder materials in addition to galvanic corrosion between WC particles and metallic binders. By contrast, the formation of passive film in the form of surface oxide in the coatings containing Cr suppressed the binder material dissolution into the solution. However, the overall corrosion resistance of the WC–CrC–Ni coating was inferior to that of the WC–Co–Cr coating due to the presence of microcracks which act as the infiltration paths of the solution. Conclusively, it is found that chemical composition of metallic binder materials and control of microcracks are the most important factors influencing the corrosion resistance of the HVOF sprayed WC cermet coatings in the strong acidic environment. Also, the wear–corrosion results such as surface morphologies and friction coefficients have been presented.

Processing of cermet such as WC–Co is not easy by cold (gas dynamic) spraying although cold spray process can eliminate the degradation of the phase as compared to conventional high velocity oxy-fuel (HVOF) spraying process. In this study, WC–12∼17%Co powders with nano- and microstructures were deposited by cold spray process using nitrogen and helium gases. Microstructural characterization and phase analysis of feedstock powders and as-deposited coatings were carried out by SEM and X-ray diffraction (XRD). The results show that there is no detrimental phase transformation and/or decarburization of WC by cold spray deposition as expected. It is also observed that nano-sized WC in the feedstock powder is maintained in the cold sprayed coatings. It seems that nano-sized WC is advantageous over micro-sized WC for cold spray deposition because higher particle velocity can be obtained with the same gas velocity. It is demonstrated that it is possible to fabricate the nano-structured WC–Co coating with low porosity and very high hardness (∼2050 HV) by cold spray deposition with reasonable powder preheating.

Processing of cermet such as WC–Co is not easy by cold spray deposition, although cold spray process can eliminate the degradation of the WC phase as compared to conventional high velocity oxygen fuel (HVOF) or plasma spraying process. In this study, WC–12%Co powders with nano-sized WC were deposited by cold spray process using helium gas. Microstructural characterization and phase analysis of feedstock powders and as-deposited coatings were carried out by SEM and XRD. The results show, as expected, that there is no detrimental phase transformation and/or decarburization of WC by cold spray deposition. It is also observed that nano-sized WC in the feedstock powder is maintained in the cold sprayed coatings. It is demonstrated that it is possible to fabricate the nano-structured WC–Co coatings with low porosity and very high hardness (∼2050 HV) by cold spray deposition with reasonable powder preheating.

Characterization of the flame sprayed and furnace fused NiCrBSiC alloy coatings with two different carbon contents and 15–45 wt.% WCCo addition is described in terms of microstructure, microhardness and differential thermal analysis. Microstructural development of these coatings before and after fusing treatment is discussed to identify the precipitates in the coatings. Optimum fusing conditions (time and temperature) for wear-testing sample were investigated in terms of microhardness and porosity of the coatings. Wear performance of these coatings was also investigated by two- and three-body abrasive and dry sliding wear experiments. The coating of 35% WC with NiCrBSiC is showing the best quality (the highest hardness and the lowest porosity). However, 25% WC addition is showing the best wear resistance for Sugaru abrasive wear test, while 40% WC addition is showing the best wear resistance for DSRW (dry sand rubber wheel) abrasive wear test. It is also shown that the dry sliding wear resistance of the 20% (and/or 30%) WCNiCrBSiC composite coating is almost 10 times better than that of the quenched and tempered JIS SUJ2 bearing steel.

In a continuous galvanizing line (CGL), three so-called pot rolls are usually used to guide steel strips in a zinc pot. Generally zinc pot rolls are coated with WC–Co to protect the pot roll surface from severe corrosion by molten zinc. The degradation process of the WC–Co coating was evaluated through analyses of coated pot rolls used in a CGL zinc pot for 33 and 56 days. The rolls were coated by high velocity oxygen fuel spraying with WC–12% Co powders that were produced through sintering and crushing processes. On the surface of the WC–Co coated rolls, several types of deposits were observed including top dross (Fe2Al5 inter-metallic compound) that might induce dross defect on the surface of galvanized steel. The diffusion depth of zinc into the WC–Co coating used for 33 days was only 10 μm, but some areas were severely attacked along cracks within the coating layer because of a preferential reaction with aluminum. Through SEM study, we observed that not only zinc but also aluminum diffused into the WC–Co coating after being in the zinc pot for 56 days. In some cases, Al–Fe–Zn layers were observed on the surface of the spray coating. Those layers were analyzed to be Fe2Al5 as their chemical compositions are very similar to those of Fe2Al5 top dross. However, they are not the Fe2Al5 dross, but the reaction products between molten zinc and the coating layer according to their morphologies.

High-temperature corrosion is a serious problem on the heat exchanger pipes of recuperators used in steel mills, because they encounter severe corrosive environments at high temperatures. These pipes are found to be corroded via oxidation, sulfidation, and molten salt corrosion. Molten salt corrosion occurs by the formation of alkali-iron sulfate as reaction products of sulfur oxide in fuel gas and sodium chloride from seawater. Many integrated steel mills are located near the sea for convenience of transportation. Salt from the seawater can affect the corrosion of the heat exchanger pipes by inducing hot corrosion. Through inspection of the used pipes of recuperators, a corrosion mechanism of the heat exchanger pipes is proposed. To evaluate the corrosion resistance of possible protective coatings for recuperators, nickel- and cobalt-based self-fluxing alloys, iron-based alloys, and chromium carbide cermet coatings were tested. The coatings with high chromium content, either as a form of carbide or as an alloying element, had excellent corrosion resistance. A Cr 3 C 2 –NiCr coating in carbide form, and Ni–45Cr–4Ti as an alloy coating can be recommended as promising coatings for the heat exchanger pipes, even in cases where they may encounter molten salt corrosion attack. The microstructure of a coating is as important as the chemical composition of the coating material. The inter-lamella pores may act as passages for molten salts. Therefore, the coatings should be carefully sprayed so that the molten salts do not penetrate into the coating layer.