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Background: The association between abdominal visceral adipose tissue and the risk of incident chronic kidney disease according to body mass index in the Asian population, remains unclear. We evaluated the impact of abdominal adiposity stratified by body mass index on the risk of incident chronic kidney disease. Methods: A cohort study included 11,050 adult participants who underwent health check-ups and re-evaluated the follow-up medical examination at a single university-affiliated healthcare center. Cross-sectional abdominal adipose tissue areas were measured using computed tomography. The primary outcome was progression to chronic kidney disease (estimated glomerular filtration rate <60 ml/min/1.73m2). The highest quartile of visceral adipose tissue was used for the cut-off of central obesity. Results: During the mean of 5.6 follow-up years, 104 incident chronic kidney disease cases were identified. The risk for chronic kidney disease incidence was significantly increased in the 3rd and 4th quartile ranges of visceral adipose tissue [hazard ratio (95% confidence interval)]: 4.59 (1.48–14.30) and 7.50 (2.33–24.20), respectively. In the analysis stratified by body mass index, the chronic kidney disease incidence risk was increased in the highest quartile range of visceral adipose tissue in the normal weight group: 7.06 (1.35–37.04). However, there was no significant relationship between visceral adipose tissue and chronic kidney disease in the obese group. Compared to the subjects with normal weight and absent central obesity, the hazard ratio for chronic kidney disease incidence was 2.32 (1.26–4.27) among subjects with normal weight and central obesity and 1.81 (1.03–3.15) among subjects with obesity and central obesity. Conclusion: Visceral adipose tissue was a significant risk factor for subsequent chronic kidney disease progression, and the association was identified only in the normal weight group. Normal-weight central obesity was associated with excess risk of chronic kidney disease, similar to the risk in the group with obesity and central obesity. [ABSTRACT FROM AUTHOR]

Despite an abundance of research related to the functional and structural changes of the brain in patients with geriatric depression, knowledge related to early alterations such as decreased white matter connectivity and their association with cognitive decline remains lacking. We aimed to investigate early alterations in hippocampal microstructure and identify their associations with memory function in geriatric patients with subclinical depression. Nineteen participants with subclinical geriatric depression and 19 healthy controls aged ≥65 years exhibiting general cognitive function within the normal range were included in the study and underwent assessments of verbal memory. Hippocampal subfield volumes were determined based on T1-weighted magnetization-prepared rapid gradient echo (T1-MPRAGE) images, while group tractography and connectometry analyses were conducted using diffusion tensor images. Our findings indicated that the volumes of whole bilateral hippocampus, cornus ammonis (CA) 1, molecular layer, left subiculum, CA3, hippocampal tail, right CA4, and granule cell/molecular layers of the dentate gyrus (GC-ML-DG) were significantly smaller in the subclinical depression group than in the control group. In the subclinical depression group, verbal learning was positively correlated with the volumes of the CA1, GC-ML-DG, molecular layer, and whole hippocampus in the right hemisphere. The fractional anisotropy of the bilateral fornix was also significantly lower in the subclinical depression group and exhibited a positive correlation with verbal learning and recall in both groups. Our results suggest that hippocampal microstructure is disrupted and associated with memory in patients with subclinical depression. [ABSTRACT FROM AUTHOR]

Few large-scale studies have been conducted to show the joint effects of mortality associated with physical activity and sedentarism. Therefore, we examined the relationship between all-cause mortality and behavioral patterns among adults in the United States. Data of 17,730 non-institutionalized US civilians aged ≥20 years were extracted from the 2007–2014 National Health and Nutrition Examination Survey. We set the criteria for metabolic equivalents as 600 according to the WHO guideline, and sedentary time as 300 min/day according to the median. The Cox proportional hazards model was adjusted for demographic and lifestyle characteristics. During the 58.54±28.18 months follow-up, all-cause mortality rate was 4% and heart-related and cancer mortality rate was 1%. Participants in the high metabolic equivalents and low sedentary time group had a lower risk of all-cause (hazard ratio = 0.41, 95% confidence interval = 0.34–0.50), cardiovascular (hazard ratio = 0.36; 95% confidence interval = 0.23–0.55), and cancer (hazard ratio = 0.55; 95% confidence interval = 0.37–0.83) mortality, compared to those in the low metabolic equivalents and high sedentary time group. Sufficient physical activity and less sedentary behavior reduce all-cause and cause-specific mortality in adults in the United States, especially cardiovascular mortality among the elderly. Additional nationwide policies to improve behavioral patterns among adults need to be implemented in the United States. [ABSTRACT FROM AUTHOR]

For successful emulsified acid treatment, it is imperative to have emulsified acid that can maintain a water-in-oil emulsion state for 24 h at room temperature and 4 h at high temperatures. As a result, a hybrid emulsified acid was developed by combining cationic and nonionic emulsifiers, guaranteeing stability at both room and high temperatures. We assessed its viscosity and explored the interaction dynamics of the emulsified acid with carbonate rock samples using rotating disk apparatus experiments. Viscosity measurements revealed a non-Newtonian shear-thinning behavior modeled using a power-law approach. We examined limestone, dolomite, and chalk disks to evaluate weight loss tendencies, dissolution rates, and diffusion coefficients when exposed to the emulsified acid and hydrochloric acid (HCl). Both the weight loss and dissolution rate demonstrated that the reactivity of HCl surpasses that of the emulsified acid by up to 2.4 times at the same rotating speed. This indicates that the emulsified acid in our study can significantly slow the rapid reaction between acid and rock due to the diffusion barrier created by the oil phase. The diffusion coefficient for the limestone sample with emulsified acid was 1.46 times greater than that of dolomite (limestone: 1.64 E–7 c m 2 / s , dolomite: 1.12 E–8 c m 2 / s , and chalk: 1.47 E–8 c m 2 / s). Consequently, understanding the rock/mineral composition of the targeted reservoir is crucial when designing matrix acidizing with emulsified acid in carbonates. In summary, it is vital to account for the impact of emulsified acid on acid-rock reaction kinetics when establishing injection parameters for carbonate acidizing. [Display omitted] • This paper presents the reaction kinetics of an emulsified acid that secures fluid stability at room and high temperatures with various carbonate disks. • It was revealed that the dissolution rate and diffusion coefficient of the emulsified acid were lower than those of hydrochloric acid. • The emulsified acid used in this study can markedly retard the rapid reaction between acid and rock because of the diffusion barrier of oil phase. • The emulsified acid used in this study can effectively stimulate carbonate reservoirs as retarded systems. [ABSTRACT FROM AUTHOR]

Surgical plates used for reconstructive surgery require a repetitive manual bending process to fit the plate to the defect during reconstruction. However, this process may not produce a plate that fits well, and repetitive bending may significantly increase the risk of plate fracture due to the accumulation of residual stress. In this study, the input angle is calculated using a proposed finite element process that considers the spring-back effect and improves the accuracy of the bending results without the need for repetitive bending. Bending tests for two arbitrary target angles (15° and 30°) are performed using the apparatus to demonstrate its effectiveness. Accurately bent plates are obtained from a single bending trial, unlike the use of another input angle that does not consider spring-back. Therefore, the proposed bending procedure could potentially replace the repetitive manual bending process and reduce the residual stress within the plate, thus lowering the risk of plate failure. [ABSTRACT FROM AUTHOR]

Surgical plates, which are used in various bone reconstruction surgeries, must be accurately bent intraoperatively or preoperatively. Manual bending is a time- and labor-consuming process, which sometimes results in residual stress to the plate after repeated operations. To overcome these problems, we propose a motorized bending apparatus for surgical plates that can automatically bend the plates to the target angle in a single trial, which may reduce the residual stress. Finite element analysis (FEA) was used to compensate for the springback and provide the proper inputs. To evaluate the performance of the apparatus, we performed tests with five reconstruction plates in the manual bending group and the apparatus-bending group, respectively, for angles of 15° and 30°. The apparatus-bending showed improved accuracy and precision. Also, the apparatus took much shorter times to perform the same tasks. The proposed method should reduce the surgical preparation time and provide convenience to surgeons. [ABSTRACT FROM AUTHOR]

Activation of p38 mitogen-activated protein kinase (MAPK) is associated with tissue fibrosis, and inhibition of p38 MAPK can attenuate the progression of fibrosis. We aimed to investigate whether p38 MAPK activity in kidney tissue confirmed by immunohistochemical staining is associated with renal tubulointerstitial fibrosis in chronic kidney disease patients with IgA nephropathy. We collected kidney biopsy specimens from 341 IgA nephropathy patients and 15 control patients to identify the clinical and histopathological factors associated with kidney tubulointerstitial fibrosis and to find an association between kidney phosphorylated p38 immunoactivity and pathological grading. In addition, we aimed to investigate whether the anti-fibrotic effect of p38 MAPK inhibition can be identified by assessing the immunostaining intensity of phosphorylated p38 in kidney tissue. A renal tubulointerstitial fibrosis model was introduced using 7-week-old C57BL/6 mice subjected to unilateral ureteral obstruction (UUO). The p38 MAPK inhibitor SB-731445 was injected intraperitoneally every day for 7 days, and changes in renal fibrosis-associated markers were investigated. Assessment of kidney biopsy specimens from IgA nephropathy patients revealed that the degree of interstitial fibrosis was significantly associated with the tissue immunoactivity of phosphorylated p38. High-grade interstitial fibrosis was associated with a low glomerular filtration rate, high proteinuria, and high-grade histopathological changes, including tubular atrophy, interstitial inflammation, and glomerular sclerosis. In a mouse UUO model, renal protein expression of COL1 and phosphorylated p38 were significantly increased, and the protein expression of COL1 and phosphorylated p38 decreased in mice administered 10 mg/kg/day p38 MAPK inhibitor. We found that kidney interstitial fibrosis is associated with increased immunoactivity of phosphorylated p38 in a UUO mouse model and in human IgA nephropathy patients and that the anti-fibrotic effect of p38 MAPK inhibition can be confirmed using immunohistochemical staining for phosphorylated p38 in kidney tissue. [ABSTRACT FROM AUTHOR]

In exoskeleton research, transparency is the degree to which a device hinders the movement of the user, a critical component of performance and usability. Transparency is most often evaluated individually, thus lacking generalization. Our goal was to systematically evaluate transparency due to inertial effects on gait of a hypothetical hip exoskeleton. We predicted that the weight distribution around the pelvis and the amount of weight applied would change gait characteristics. We instructed 21 healthy individuals to walk on a treadmill while bearing weights on the pelvis between 4 and 8 kg in three different configurations, bilaterally, unilaterally (left side) and on the lumbar portion of the back (L4). We measured kinematics, kinetics, and muscle activity during randomly ordered trials of 1.5 min at typical walking speed. We also calculated the margin of stability to measure medial–lateral stability. We observed that loading the hips bilaterally with 4 kg had no changes in kinematics, kinetics, dynamic stability, or muscle activity, but above 6 kg, sagittal joint power was increased. Loading the lumbar area increased posterior pelvic tilt at 6 kg and decreased dynamic stability at 4 kg, with many individuals reporting some discomfort. For the unilateral placement, above 4 kg dynamic stability was decreased and hip joint power was increased, and above 6 kg the pelvis begins to dip towards the loaded side. These results show the different effects of weight distribution around the pelvis. This study represents a novel, systematic approach to characterizing transparency in exoskeleton design (clinicaltrials.gov: NCT05120115). [ABSTRACT FROM AUTHOR]

Chronic kidney disease (CKD) is an important social health problem characterized by a decrease in the kidney glomerular filtration rate (GFR). In this study, we analyzed genome-wide association studies for kidney disease-related traits using data from a Korean adult health screening cohort comprising 7,064 participants. Kidney disease-related traits analyzed include blood urea nitrogen (BUN), serum creatinine, estimated GFR, and uric acid levels. We detected two genetic loci (SLC14A2 and an intergenic region) and 8 single nucleotide polymorphisms (SNPs) associated with BUN, 3 genetic loci (BCAS3, C17orf82, ALDH2) and 6 SNPs associated with serum creatinine, 3 genetic loci (BCAS3, C17orf82/TBX2, LRP2) and 7 SNPs associated with GFR, and 14 genetic loci (3 in ABCG2/PKD2, 2 in SLC2A9, 3 in intergenic regions on chromosome 4; OTUB1, NRXN2/SLC22A12, CDC42BPG, RPS6KA4, SLC22A9, and MAP4K2 on chromosome 11) and 84 SNPs associated with uric acid levels. By comparing significant genetic loci associated with serum creatinine levels and GFR, rs9895661 in BCAS3 and rs757608 in C17orf82 were simultaneously associated with both traits. The SNPs rs11710227 in intergenic regions on chromosome 3 showing significant association with BUN is newly discovered. Genetic variations of multiple gene loci are associated with kidney disease-related traits, and differences in associations between kidney disease-related traits and genetic variation are dependent on the population. The meanings of the mutations identified in this study will need to be reaffirmed in other population groups in the future. [ABSTRACT FROM AUTHOR]

Diabetic nephropathy (DN) is associated with kidney fibrosis. A previous study revealed that periostin (POSTN) contributes to kidney fibrosis. This study examined the role of POSTN in DN. The urinary concentrations of POSTN and TNC increased according to the severity of DN in human samples. Streptozotocin (STZ) was administered after unilateral nephrectomy (UNXSTZ) to induce DN in wild-type and Postn-null mice. Four experimental groups were generated: wild-typeham (WT Sham), wild-type UNXSTZ (WT STZ), Postn-null Sham (KO Sham), and Postn-null UNXSTZ (KO STZ). After 20 weeks, the KO STZ group had lower levels of urine albumin excretion, glomerular sclerosis, and interstitial fibrosis than those of the WT STZ group. Additionally, the KO STZ group had lower expression of fibrosis markers, including TNC. The KO STZ group showed better glucose regulation than the WT STZ model. Furthermore, the KO STZ group exhibited significantly preserved pancreatic islet integrity and insulin expression. HK-2 cells were used to observe the aggravation of fibrosis caused by POSTN under TGF-β conditions. We stimulated INS-1 cells with streptozotocin and evaluated the viability of these cells. The anti-POSTN antibody treatment of INS-1 cells with streptozotocin resulted in higher cell viability than that with treatment with streptozotocin alone. The absence of POSTN in DN contributes to renal fibrosis alleviation by improving pancreatic β-cell function. Additionally, there is an association between POSTN and TNC. [ABSTRACT FROM AUTHOR]

This study presents experimental results on the variation of relative permeability due to clay types and contents in low salinity water-flooding. To analyze the effect of clay types and contents on relative permeability, core-flooding using unconsolidated sand core samples was conducted. Relative permeability curves were measured from the experiments using the Johnson, Bossler, and Naumann (JBN) method. From the results, the moving range (S or -S wi ) of the relative permeability curve was proportional to the clay contents of kaolinite. The moving range for illite also showed a relative permeability curve proportional to the clay contents, but it was less than that for kaolinite. To extend the equation of the Honarpour end-point relative permeability curves in low salinity water-flooding, end-point relative permeability curves were matched with the experimental relative permeability curves by changing the Honarpour index N o and N w . Then, the difference of N o and N w between the conventional water-flooding and the low salinity water-flooding was correlated with the clay contents. Based on the results, extended functions of index N o and N w were proposed to describe the relative permeability curves applied to low salinity water-flooding. It is believed that end-point relative permeability curves can be determined by the proposed N o and N w instead of the conventional exponent index in low salinity water-flooding with reservoirs containing kaolinite. [ABSTRACT FROM AUTHOR]

Alcohol-induced hippocampal atrophy has been well documented in many studies and is known to affect various subfields. Given the functional heterogeneity of these subfields, we investigated the precise effects of alcohol-induced damage in these areas. Twenty-six male patients with alcohol dependence (alcohol group) and twenty-six age-matched male healthy social drinkers were recruited from a mental health hospital and the community respectively, with the aim of comparing the hippocampal subfields between groups. Each participant underwent a 3 T MRI scan. Hippocampal subfield volumes were estimated using an automated procedure and drinking history recorded using Lifetime Drinking History, Alcohol Use Disorder Identification Test, and the Brief Michigan Alcoholism Screening Test. The alcohol group showed a lower total hippocampus volume, specifically in the left presubiculum, fimbria, and bilateral subiculum. Regression analysis assessing the influence of age and group showed that group was a more significant factor than age in most subfields. Our findings suggest that alcohol dependence alters hippocampal subfield volumes. Further longitudinal studies on the interaction of structural and neurocognitive changes would improve our understanding of brain structural changes resulting from long-term alcohol consumption. [ABSTRACT FROM AUTHOR]

The significance of minimal increases in serum creatinine below the levels indicative of the acute kidney injury (AKI) stage is not well established. We aimed to investigate the influence of pre-stage AKI (pre-AKI) on clinical outcomes. We enrolled a total of 21,261 patients who were admitted to the Seoul National University Bundang Hospital from January 1, 2013 to December 31, 2013. Pre-AKI was defined as a 25–50% increase in peak serum creatinine levels from baseline levels during the hospital stay. In total, 5.4% of the patients had pre-AKI during admission. The patients with pre-AKI were predominantly female (55.0%) and had a lower body weight and lower baseline levels of serum creatinine (0.63 ± 0.18 mg/dl) than the patients with AKI and the patients without AKI (P < 0.001). The patients with pre-AKI had a higher prevalence of diabetes mellitus (25.1%) and malignancy (32.6%). The adjusted hazard ratio of in-hospital mortality for pre-AKI was 2.112 [95% confidence interval (CI), 1.143 to 3.903]. In addition, patients with pre-AKI had an increased length of stay (7.7 ± 9.7 days in patients without AKI, 11.4 ± 11.4 days in patients with pre-AKI, P < 0.001) and increased medical costs (4,061 ± 4,318 USD in patients without AKI, 4,966 ± 5,099 USD in patients with pre-AKI, P < 0.001) during admission. The adjusted hazard ratio of all-cause mortality for pre-AKI during the follow-up period of 2.0 ± 0.6 years was 1.473 (95% CI, 1.228 to 1.684). Although the adjusted hazard ratio of pre-AKI for overall mortality was not significant among the patients admitted to the surgery department or who underwent surgery, pre-AKI was significantly associated with mortality among the non-surgical patients (adjusted HR 1.542 [95% CI, 1.330 to 1.787]) and the patients admitted to the medical department (adjusted HR 1.384 [95% CI, 1.153 to 1.662]). Pre-AKI is associated with increased mortality, longer hospital stay, and increased medical costs during admission. More attention should be paid to the clinical significance of pre-AKI. [ABSTRACT FROM AUTHOR]

We investigated the association between major persistent organic pollutants (POPs) exposure and chronic kidney disease (CKD) among general adult population of Korea. For this purpose, a subset of the adult population (n = 1276) participated in Korean National Environmental Health Survey (KoNEHS) Cycle 3 (2015–2017) were analyzed for twenty-four POPs in serum, including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs), and were derived for estimated glomerular filtration rate (eGFR) and urinary albumin-to-creatinine ratio (uACR). Multivariable linear regression was conducted to assess the association between POPs exposure and CKD-related parameters including eGFR and uACR. As sensitivity analyses, principal component analysis was conducted. Moreover, the U.S. National Health and Nutrition Examination Survey (NHANES) 1999–2004 data were chosen to compare with the observations of the Korean adults. Approximately 7.7% of the Korean adult population possessed CKD based on either eGFR (<60 ml/min/1.73 m2) or uACR (≥30 mg/g) criteria. Among the POPs that were detected in ≥70% of the subjects, PCB153 (β = −1.61, 95% CI: −2.55, −0.67, P = 0.001) and PCB180 (β = −1.47, 95% CI: −2.53, −0.40, P = 0.007) exhibited significant associations with decreased eGFR, especially in females. In male participants, hexachlorobenzene (HCB) was associated with eGFR (β = −0.79, 95% CI: −1.53, −0.04, P = 0.040). Sex-dependent associations with eGFR were also shown in the PCA model. Moreover, the sex-dependent associations of PCBs were similarly observed in the adult populations of the US NHANES. However, POPs exposure was not associated with uACR, regardless of association model or population. The observed associations of PCBs are supported by several experimental studies reported elsewhere. To our knowledge, it is the first report that suggests significant associations of PCBs and HCB with eGFR among general population, and further validations in other populations are warranted. [Display omitted] • Major POPs and CKD parameters were associated in a general adult population. • A subset of KoNEHS Cycle 3 was randomly selected after age and sex stratification. • Serum PCB153 and 180 were associated with reduced eGFR. • For PCB153, 180, and HCB, sex-dependent associations with eGFR were observed. • Similar associations were found in the US adults participated in NHANES 1999–2016. [ABSTRACT FROM AUTHOR]

Aim To investigate the effect of microtubule stabilization with low-dose paclitaxel on renal fibrosis, focusing on the transforming growth factor-β1 (TGF-β1)-induced plasminogen activator inhibitor-1 (PAI-1) signaling cascade. Methods Forty-eight rats were randomly assigned to four groups: sham/vehicle, sham/paclitaxel, unilateral ureteral obstruction (UUO)/vehicle and UUO/paclitaxel. Rats were treated with a 0.3 mg/kg intraperitoneal dose of paclitaxel or vehicle twice per week for 14 days. Half of the rats in each group were sacrificed respectively on day 7 and 14 after operation. Inner medullar collecting duct (IMCD) cells stimulated with TGF-β1 were incubated with 0, 1 and 2 nM paclitaxel for 24 and 72 hours. Histological changes were assessed using periodic acid-Schiff and Masson's trichrome. The TGF-β1-induced PAI-1 signaling and status of extracellular matrix proteins were evaluated by western blot analysis. Results In the UUO kidneys, paclitaxel significantly attenuated tubular damage and interstitial collagen deposition, as well as α-smooth muscle actin (α-SMA), TGF-β1 and PAI-1 protein expression. Paclitaxel also inhibited the UUO-induced activation of Smad2/3 and c-Jun N-terminal kinase (JNK). However, paclitaxel treatment did not inhibit extracellular signal-regulated kinase 1/2 (ERK1/2) or p38 expression. In TGF-β1-treated IMCD cells, treatment with 1 and 2 nM paclitaxel for 72 h reduced fibronectin, α-SMA and PAI-1 protein expression. Moreover, a 2 nM dose of paclitaxel for 24 h significantly inhibited the TGF-β1-stimulated activation of Smad2/3, JNK and ERK1/2 in IMCD cells. Conclusion Paclitaxel at low non-cytotoxic doses ameliorates renal fibrosis by inhibiting multiple steps in the TGF-β1-induced PAI-1 signaling including Smads and mitogen-activated protein kinases. [ABSTRACT FROM AUTHOR]

Glomerular hyperfiltration is recognized as an early marker of progressive kidney dysfunction in the obese population. This study aimed to identify the relationship between glomerular hyperfiltration and body fat distribution measured by computed tomography (CT) in healthy Korean adults. The study population included individuals aged 20–64 years who went a routine health check-up including an abdominal CT scan. We selected 4,378 individuals without diabetes and hypertension. Glomerular filtration rate was estimated using the CKD-EPI equation, and glomerular hyperfiltration was defined as the highest quintile of glomerular filtration rate. Abdominal adipose tissue areas were measured at the level of the umbilicus using a 16-detector CT scanner, and the cross-sectional area was calculated using Rapidia 2.8 CT software. The prevalence of glomerular hyperfiltration increased significantly according to the subcutaneous adipose tissue area in men (OR = 1.74 (1.16–2.61), P for trend 0.016, for the comparisons of lowest vs. highest quartile) and visceral adipose tissue area in women (OR = 2.34 (1.46–3.75), P for trend < 0.001) in multivariate analysis. After stratification by body mass index (normal < 23 kg/m2, overweight ≥ 23 kg/m2), male subjects with greater subcutaneous adipose tissue, even those in the normal BMI group, had a higher prevalence of glomerular hyperfiltration (OR = 2.11 (1.17–3.80), P for trend = 0.009). Among women, the significance of visceral adipose tissue area on glomerular hyperfiltration resulted from the normal BMI group (OR = 2.14 (1.31–3.49), P for trend = 0.002). After menopause, the odds ratio of the association of glomerular hyperfiltration with subcutaneous abdominal adipose tissue increased (OR = 2.96 (1.21–7.25), P for trend = 0.013). Subcutaneous adipose tissue areas and visceral adipose tissue areas are positively associated with glomerular hyperfiltration in healthy Korean adult men and women, respectively. In post-menopausal women, visceral adipose tissue area shows significant positive association with glomerular hyperfiltration as in men. [ABSTRACT FROM AUTHOR]

Background: Controversy persists regarding the appropriate initiation timing of renal replacement therapy for patients with end-stage renal disease. We evaluated the effect of dialysis initiation timing on clinical outcomes. Initiation times were classified according to glomerular filtration rate (GFR). Methods: We enrolled a total of 1691 adult patients who started dialysis between August 2008 and March 2013 in a multi-center, prospective cohort study at the Clinical Research Center for End Stage Renal Disease in the Republic of Korea. The patients were classified into the early-start group or the late-start group according to the mean estimated GFR value, which was 7.37 ml/min/1.73 m2. The primary outcome was patient survival, and the secondary outcomes were hospitalization, cardiovascular events, vascular access complications, change of dialysis modality, and peritonitis. The two groups were compared before and after matching with propensity scores. Results: Before propensity score matching, the early-start group had a poor survival rate (P<0.001). Hospitalization, cardiovascular events, vascular access complications, changes in dialysis modality, and peritonitis were not different between the groups. A total of 854 patients (427 in each group) were selected by propensity score matching. After matching, neither patient survival nor any of the other outcomes differed between groups. Conclusions: There was no clinical benefit after adjustment by propensity scores comparing early versus late initiation of dialysis. [ABSTRACT FROM AUTHOR]

Background: The nature of cost-saving effects of early referral to a nephrologist in patients with chronic kidney disease (CKD) is not fully evaluated. We evaluated the health care costs before and after dialysis according to the referral time. Methods: A total of 879 patients who were newly diagnosed as having end-stage renal disease from August 2008 to June 2011 were prospectively enrolled. The early referral (ER) group was defined as patients who were referred to a nephrologist more than a year before dialysis and had visited a nephrology clinic 2 or more times. Patients whose referral time was less than a year were considered the late referral (LR) group. Information about medical costs was acquired from the claim data of the Korea Health Insurance Review and Assessment Service. Results: The total medical costs during the first 12 months after the initiation of dialysis were not different between the 526 ER patients and the 353 LR patients. However, the costs of the ER patients during the first month were significantly lower than those of the LR patients (ER vs. LR: 3029±2219 vs. 3438±2821 US dollars [USD], P = 0.025). The total 12-month health care costs before the initiation of dialysis were significantly lower in the ER group (ER vs. LR: 6206±5873 vs. 8610±7820 USD, P<0.001). In the multivariate analysis, ER significantly lowered the health care costs during the 12 months before (2534.0±436.2 USD, P<0.001) and the first month (428.5±172.3 USD, P = 0.013) after the initiation of dialysis. Conclusions: The ER of patients with CKD to a nephrologist is associated with decreased medical costs during the pretreatment period of renal replacement therapy and the early period of dialysis initiation. [ABSTRACT FROM AUTHOR]

Abstract: Extensive deposits of naturally occurring gas hydrates have been found in many regions of the world. Because it contains a large amount of methane, hydrates have been considered as a future energy resource. Although natural gas hydrates are known to occur in numerous marine and permafrost regions, a little is known about the technology required to produce gas from hydrate reservoirs. This work discusses the recovery of gas from hydrate reservoirs through laboratory measurement. In this study, an experimental apparatus has been designed and set up to analyze the dissociating phenomena of hydrate in porous rock. Depressurization experiments have been carried out to investigate the dissociation characteristics and the productivity of dissociated gas. The results of the experiment present the comparison of gas productivities and propagations of dissociation front in relation to time as hydrate is depressurized in different conditions. The flow behavior of dissociated gas in porous rock and the efficiency of production have also been investigated. The results of this study can be useful for the gas recovery from hydrate reservoirs. [ABSTRACT FROM AUTHOR]

A polymethacrylate copolymer comprised of light-emissive cyano-substituted dihexylfluorenevinylene (CN-DHFV) side groups and photo-cross-linkable 4-(4-methoxycinnamoyloxy)biphenyl (MCB) mesogenic side groups was synthesized and characterized. Irradiating a thin copolymer film with linearly polarized ultraviolet (LPUV) light and subsequent annealing generated a cooperative molecular reorientation of both side groups parallel to the polarization (E) of LPUV light. The resulting reoriented film showed a polarized light emission of the CN-DHFV groups with a polarization ratio of 5.6. [ABSTRACT FROM AUTHOR]

• Dimensional synthesis compared four-, six- and eight-bar mechanism gait trainers • Eight-bar configuration had greater kinematic accuracy with constant input velocity • Kinematic accuracy was similar for all mechanisms with well-controlled input Single degree-of-freedom mechanized gait trainers employing linkage mechanisms can imitate the gait trajectory of the human user at a potentially lower cost than current commercial solutions. Our goal was to evaluate recently introduced four-, six- and eight-bar designs from the standpoint of kinematics, that is, the ability to follow a natural gait pattern. Based on a gait database of 113 healthy individuals, we synthesized mechanisms allowing two link length adjustments and compared trajectory and path accuracy of the ankle position across mechanisms. We used cross-validation to obtain data-independent accuracy measures. We used gait trajectories from a large human database and predicted additional trajectories to represent the effects of varying heights and speeds. We found that trajectory error was significantly lower in the eight-bar mechanism (3.76 ± 0.18 cm, mean ± SD) than the four- (6.84 ± 0.37 cm) and six-bar (7.15 ± 0.48 cm) configurations (p < 0.0001). However, we did not observe differences in time-independent path error between configurations or in mechanical advantage (p > 0.05). We conclude that the optimized eight-bar configuration is best when the mechanism is tied to a constant velocity actuator, whereas the optimized four-bar mechanism performs as well if the actuator is well-controlled. [ABSTRACT FROM AUTHOR]

Several studies have revealed that nanofluid and smart water flooding are cost-effective methods, considering the effect of nanoparticles and potential determining ions (PDIs) for enhanced oil recovery in carbonated reservoirs. This study presents the performance of nano-smart water synthesized with surface-modified SiO 2 nanoparticles dispersed in PDI-controlled seawater (SW), ensuring dispersion stability in high-temperature and high-salinity reservoirs. The interfacial tension (IFT) and contact angle of the oil/nano-smart water/carbonate rock system were measured using kerosene as an oil phase. At this time, nanoparticle concentrations ranged from 0.5 to 3 wt% and PDI concentrations ranged from 1,000 to 5,000 ppm, such as KCl, MgCl 2 , MgSO 4 , and K 2 SO 4. In addition, the IFT and contact angle of SW, low salinity water (LSW), and nanofluid were measured for comparison. It was observed that at nanoparticle concentrations higher than 1 wt%, the IFT values of nano-smart water remained constant or decreased slightly to below 31.91 mN/m compared with nanofluids at 32.18 mN/m, regardless of PDI type and concentration. This indicates that using nano-smart water instead of LSW and SW is expected to reduce the IFT in the oil/water system. The contact angle measurements revealed that the wettability index is 2.57–5.07 times higher in nano-smart water than in nanofluids. This implies that wettability alteration is accelerated by the synergistic effect of PDIs and nanoparticles. Specifically, PDI control with MgSO 4 or K 2 SO 4 is highly effective in changing the contact angle of carbonate from strongly oil-wet to strongly water-wet due to the ion exchange reaction of SO 4 2- in oil/water/carbonate rock system. The nano-smart water used in this study is expected to be utilized as an injection fluid under harsh conditions for enhanced oil recovery. [Display omitted] [ABSTRACT FROM AUTHOR]

• Implementation of GPU accelerated Fast Fourier Transformation to solve Cahn-Hilliard equation. • Quantitative evaluation of effect of magnetic ordering on the microstructural evolution. • Propose novel way to quantify two phase structure generated by the spinodal decomposition structure. This study aims to investigate the effect of magnetic ordering on spinodal decomposition behavior in the Fe-Cr system using graphics processing unit(GPU) parallelization. We modify the CALPHAD-type free energy to remove its critical behavior near the paramagnetic-ferromagnetic transition. We solve the Cahn-Hilliard equation using a semi-implicit Fourier spectral method, parallelizing the code to run on a GPU via compute unified device architecture and OpenMP. We find that the GPU parallelization gives better performance than that of OpenMP when using fast Fourier transforms to solve the Cahn-Hilliard equation. We conduct nine sets of simulations to examine the effect of magnetic ordering, and we found that it alters the interfacial energy between Cr-rich and Cr-depleted phases, equilibrium concentrations, and energy barrier for phase transformations. We apply a phase-field method to examine in detail how these changes affect the microstructural evolution, quantitatively evaluating the microstructures obtained in terms of the precipitate number density, average phase area, and phase boundary density along certain auxiliary lines to analyze the effects of magnetic ordering. [ABSTRACT FROM AUTHOR]

Organophosphate esters (OPEs) have been widely used in building materials and consumer products as flame retardants and plasticizers. In vitro studies have suggested adverse effects of OPEs on the kidney. Despite accumulating evidence indicating widespread exposure to OPEs, their association with renal function in humans has not been evaluated. This study aims to investigate the association between OPEs exposure and chronic kidney disease (CKD) among the general US adult population by employing data from the US National Health and Nutrition Examination Survey (NHANES) 2013–2014. Among 1578 adults who were not currently pregnant, the associations of the urinary OPE metabolites with two CKD-related parameters, i.e., estimated glomerular filtration rate (eGFR) and albumin-to-creatinine ratio (ACR), and CKD were assessed. To account for urine dilution, in addition to conventional creatinine-adjustment, covariate-adjusted creatinine standardization, which controls for potential confounding by kidney function, was employed. Multi-pollutant models were also constructed to verify the associations observed in the models on individual OPE metabolites. The urinary bis(2-chloroethyl) phosphate (BCEP) level was negatively associated with eGFR only with the covariate-adjusted standardization method, but not with the conventional creatinine adjustment. In addition, both bis(1,3-dichloro-2-propyl) phosphate (BDCIPP) and di-n-butyl phosphate (DNBP) were positively associated with the ACR, regardless of methods of urine dilution adjustment. These three compounds were also associated with CKD. Following adjusting urine dilution with the covariate-adjusted standardization method, the association became more evident. Moreover, similar results were observed in the secondary analysis with the multi-pollutant models. Among the US general population, several OPEs were identified as potential chemical determinants of CKD. Experimental studies are warranted to understand the potential mechanisms underlying this observation. • Several OPEs were associated with CKD among general US adults. • Urinary BCEP level was negatively associated with eGFR. • Urinary BDCIPP and DNBP levels were positively associated with ACR. • Associations became more pronounced with a novel urine dilution adjustment. [ABSTRACT FROM AUTHOR]

Background: The effect of dyslipidemia on kidney disease outcomes has been inconclusive, and it requires further clarification. Therefore, we aimed to investigate the effects of genetic factors on the association between dyslipidemia and the risk of chronic kidney disease (CKD) using polygenic risk score (PRS). Methods: We analyzed data from 373,523 participants from the UK Biobank aged 40–69 years with no history of CKD. Baseline data included plasma levels of total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglyceride, as well as genome-wide genotype data for PRS. Our primary outcome, incident CKD, was defined as a composite of estimated glomerular filtration rate < 60 ml/min/1.73 m2 and CKD diagnosis according to International Classification of Disease-10 codes. The effects of the association between lipid levels and PRS on incident CKD were assessed using the Cox proportional hazards model. To investigate the effect of this association, we introduced multiplicative interaction terms into a multivariate analysis model and performed subgroup analysis stratified by PRS tertiles. Results: In total, 4,424 participants developed CKD. In the multivariable analysis, PRS was significantly predictive of the risk of incident CKD as both a continuous variable and a categorized variable. In addition, lower total cholesterol, LDL-C, HDL-C, and higher triglyceride levels were significantly associated with the risk of incident CKD. There were interactions between triglycerides and intermediate and high PRS, and the interactions were inversely associated with the risk of incident CKD. Conclusions: This study showed that PRS presented significant predictive power for incident CKD and individuals in the low-PRS group had a higher risk of triglyceride-related incident CKD. [ABSTRACT FROM AUTHOR]

The purpose was to prepare a (3-glycidoxypropyl)-trimethoxysilane (GPTMS)-SiO 2 nanofluid and analyze the effect of nanofluid injection on carbonate reservoirs. GPTMS-modified silica nanoparticles (SNPs) were investigated by Fourier transform infrared spectroscopy (FTIR) and elemental analysis. FTIR spectra of C-H stretching vibrations at 2950 cm−1, indicating silica surface modification with GPTMS, were observed when the GPTMS in the feed was greater than 0.7 mmol/g. Further, a stable nanofluid was obtained when the amount of grafted silane was close to 0.73 mmol/g, the theoretical maximum amount of grafted silanes. To evaluate the performance of surface-modified SNPs for enhanced oil recovery in carbonate reservoirs, wettability alteration tests comprising flotation test and contact angle measurements using powder and plug samples of carbonates, respectively, were performed with different SNP concentrations. Powder samples were successfully changed from oil-wet to water-wet, and the contact angle of the plug sample decreased by up to 62.8% as a result of the reaction of the nanofluid; however, it did not reduce interfacial tension (IFT) as effectively as IFT reducer additives. A coreflooding test was conducted to determine the effective parameters of the enhanced oil recovery with the GPTMS-nanofluid, such as SNP concentration, injection rate, and rock properties. The nanofluid injection increased oil recovery by approximately 20% compared to conventional waterflooding through incremental oil recovery, mainly attributed to wettability alteration. Therefore, we expect the nanofluid to dramatically increase the oil recovery in strongly oil-wet carbonate reservoirs under high-salinity conditions. [Display omitted] [ABSTRACT FROM AUTHOR]

Acute kidney injury (AKI) in COVID-19 patients is associated with poor prognosis. Characterization of AKI by timing and trajectory and early prediction of AKI progression is required for better preventive management and the prediction of patient outcomes. A total of 858 patients who were hospitalized due to coronavirus disease 2019 (COVID-19) were retrospectively enrolled from December 2020 to August 2021. The occurrence of AKI was evaluated throughout hospitalization. The hazard ratios (HRs) of mortality outcomes according to the trajectory of AKI were measured using Cox regression models after adjustment for multiple variables. Among 858 patients, 226 (26.3%) presented AKI at admission, and 44 (5.1%) developed AKI during hospitalization. Patients with AKI at admission or hospital-acquired AKI had a higher risk of mortality than those without AKI, with HRs of 9.87 (2.81–34.67) and 13.74 (3.57–52.84), respectively. Of 226 patients with AKI at admission, 104 (46.0%) recovered within 48 hr, 83 (36.7%) had AKI beyond 48 hr and recovered in 7 days, and 39 (17.3%) showed no recovery from AKI on Day 7. Delayed recovery and persistent AKI were significantly associated with an increased risk of mortality, with HRs of 4.39 (1.06–18.24) and 24.33 (7.10–83.36), respectively. The onset and progression of AKI was significantly associated with in-hospital mortality in patients with COVID-19. A thorough observation of the recovery trajectory of early AKI after infection is necessary. [ABSTRACT FROM AUTHOR]

Decreased total CO2 (tCO2) is significantly associated with all-cause mortality in critically ill patients. Because of a lack of data to evaluate the impact of tCO2 in patients with COVID-19, we assessed the impact of tCO2 on all-cause mortality in this study. We retrospectively reviewed the data of hospitalized patients with COVID-19 in two Korean referral hospitals between February 2020 and September 2021. The primary outcome was in-hospital mortality. We assessed the impact of tCO2 as a continuous variable on mortality using the Cox-proportional hazard model. In addition, we evaluated the relative factors associated with tCO2 ≤ 22 mmol/L using logistic regression analysis. In 4,423 patients included, the mean tCO2 was 24.8 ± 3.0 mmol/L, and 17.9% of patients with tCO2 ≤ 22 mmol/L. An increase in mmol/L of tCO2 decreased the risk of all-cause mortality by 4.8% after adjustment for age, sex, comorbidities, and laboratory values. Based on 22 mmol/L of tCO2, the risk of mortality was 1.7 times higher than that in patients with lower tCO2. This result was maintained in the analysis using a cutoff value of tCO2 24 mmol/L. Higher white blood cell count; lower hemoglobin, serum calcium, and eGFR; and higher uric acid, and aspartate aminotransferase were significantly associated with a tCO2 value ≤ 22 mmol/L. Decreased tCO2 significantly increased the risk of all-cause mortality in patients with COVID-19. Monitoring of tCO2 could be a good indicator to predict prognosis and it needs to be appropriately managed in patients with specific conditions. [ABSTRACT FROM AUTHOR]

GPTMS ((3-Glycidoxypropyl) trimethoxysilane)-SiO 2 nanofluids have the ability to alter the wettability of a rock surface and high colloidal stability, therefore, they can be used as injection fluids to enhance oil recovery in high-salinity and high-temperature reservoirs. The purpose of this study is to prepare GPTMS-SiO 2 nanofluids that are stable under extreme reservoir conditions and investigate their rheological characteristics. Nanofluids with nanoparticle concentrations of 0.1 to 3 wt% were prepared and dispersed in 10 wt% API (American Petroleum Institute) brine, which served as the base fluid. The apparent viscosity of the base fluid and GPTMS-SiO 2 nanofluids was measured in the shear rate range 3.7 to 93.1 s−1 between the temperatures of 5 and 85 °C. It was observed to be a function of temperature, but remained constant with the increase in shear rate. On the other hand, the nanofluids exhibited pseudoplastic behavior (shear thinning). The apparent viscosity of the nanofluids tended to increase with decreasing temperature and increasing particle concentration. The consistency index and power law index of the power law fluid model are used for the analysis of the flow behavior of the nanofluids. The consistency indices of GPTMS-SiO 2 nanofluids were observed to be well matched with the exponential function, and the power law indices showed high correlations with the specific particle concentration and temperature conditions. The results revealed that the rheological characteristics of GPTMS-SiO 2 nanofluids are functions of particle concentration and temperature at specific conditions. [ABSTRACT FROM AUTHOR]

This study presents nano-smart water synthesized with grafted SiO 2 nanoparticles dispersed potential determining ion (PDI) controlled seawater to enhance oil recovery in carbonate reservoirs with high temperatures and high salinity. Phase behavior observation, dynamic light scattering (DLS), and transmission electron microscopy (TEM) were performed to evaluate the dispersion stability of the synthesized nano-smart water with different particle concentrations at 25 ℃ and 80 ℃. In addition, a fluid miscibility test (FMT) was conducted using seawater with controlled salinity and PDI type and concentration. The results of dispersion stability showed that stable fluids without aggregation and precipitation, with an average particle size of less than 100 nm, could be synthesized at room and high temperature in seawater at the nanoparticle concentration 0.5 wt% or more. The dispersion stability of the synthesized nano-smart water was successfully achieved without aggregation and precipitation, with an average particle size of less than 100 nm, at room and high temperatures when the nanoparticle concentration is higher than 0.5 wt%. After performing the FMT with a high-salinity level of up to 200,000 ppm, and implementing PDI control using K+, Mg2+, Cl-, and SO 4 2-, the nanoparticles in nano-smart water still had an average particle size ranging from 32.2 to 54.1 nm. This indicates that the colloidal dispersion was stable despite the high-salinity levels and PDI control. Therefore, the SW-based nano-smart water is expected to be used as a stable injection fluid in high-temperatures and high-salinity carbonate reservoirs. [Display omitted] [ABSTRACT FROM AUTHOR]

Decreased total CO2 (tCO2) is significantly associated with all-cause mortality in critically ill patients. Because of a lack of data to evaluate the impact of tCO2 in patients with COVID-19, we assessed the impact of tCO2 on all-cause mortality in this study. We retrospectively reviewed the data of hospitalized patients with COVID-19 in two Korean referral hospitals between February 2020 and September 2021. The primary outcome was in-hospital mortality. We assessed the impact of tCO2 as a continuous variable on mortality using the Cox-proportional hazard model. In addition, we evaluated the relative factors associated with tCO2 ≤ 22 mmol/L using logistic regression analysis. In 4,423 patients included, the mean tCO2 was 24.8 ± 3.0 mmol/L, and 17.9% of patients with tCO2 ≤ 22 mmol/L. An increase in mmol/L of tCO2 decreased the risk of all-cause mortality by 4.8% after adjustment for age, sex, comorbidities, and laboratory values. Based on 22 mmol/L of tCO2, the risk of mortality was 1.7 times higher than that in patients with lower tCO2. This result was maintained in the analysis using a cutoff value of tCO2 24 mmol/L. Higher white blood cell count; lower hemoglobin, serum calcium, and eGFR; and higher uric acid, and aspartate aminotransferase were significantly associated with a tCO2 value ≤ 22 mmol/L. Decreased tCO2 significantly increased the risk of all-cause mortality in patients with COVID-19. Monitoring of tCO2 could be a good indicator to predict prognosis and it needs to be appropriately managed in patients with specific conditions. [ABSTRACT FROM AUTHOR]

The main challenge of nanotechnologies for enhanced oil recovery (EOR) in carbonate reservoirs is to maintain the colloidal stability of nanoparticle dispersion (nanofluid) under the reservoir conditions with high salinity and high temperature. This study presents a nanofluid as an injection fluid for EOR under the extreme condition. The nanofluid was composed of surface-modified silica nanoparticles by a silane coupling agent (GPTMS, (3-Glycidoxypropyl)trimethoxysilane). The particle size distribution and particle aggregation were measured and observed to evaluate colloidal stability of the nanofluid by the light scattering and electron microscopy methods. As a result, the colloidal stability of the nanofluid was achieved at the salinity up to 20 wt% of base fluid at 90 °C, when the amount of GPTMS was 1 mmol/g. The wettability alteration test of carbonate rocks was carried out to validate the applicability of the nanofluid in the reservoir conditions. The results showed that the rock wettability of dolomite and limestone was effectively altered to neutral-wet and water-wet from strongly oil-wet, respectively, by the nanofluid with a small portion of particle concentration. Therefore, it is believed that the nanofluid can be an effective EOR agent in carbonate reservoirs. [ABSTRACT FROM AUTHOR]

This study presents experimental results on the reaction kinetics of dolomite with fresh and spent acid in carbonate acidizing. Spent acid is defined as a partially reacted acid involving reaction products, such as calcium and magnesium ions, during an acid-rock reaction. A newly designed apparatus was developed to quantify the effect of spent acid on the acid-rock reaction kinetics at reservoir conditions. A total of 4 runs with 36 experiments at same conditions using the apparatus were repeatedly carried out to investigate the reaction kinetics of dolomite rock under the various concentrations of fresh acid and spent acid. The reaction results showed the dolomite disk was more dissolved in the spent acid than the fresh acid. Moreover, it was observed that the kinematic viscosity was higher, and the pH was lower in the spent acid, when compared with the fresh acid. From the results, it was revealed that the dissolution rate and diffusion coefficient for spent acid were higher than those of fresh acid due to the higher kinematic viscosity and the lower pH of spent acid. This means that the chemical reaction becomes more vigorous due to the long contact time and high acidity of the spent acid at the surface of the dolomite disk. These results suggest that the uncommon ion effect by the impurities, such as ferric oxide and aluminum oxide in clay, which is not related to the reaction of HCl and dolomite, can promote the reactions. A conventional approach using fresh acid could result in significant errors in determining the injection parameters, such as injection rate, volume, and pumping schedule in a carbonate acidizing job, because of the underestimated the dissolution rate and diffusion coefficient. Therefore, the effect of spent acid on acid-rock reaction kinetics should be essentially considered to design the injection conditions in carbonate acidizing. [ABSTRACT FROM AUTHOR]

Depression is a preventable and treatable mental health condition. Therefore, there are important clinical implications for identifying people with the highest mortality risk in a nationally representative sample. This study included 26,207 participants aged ≥18 years from the 2005–2014 National Health and Nutrition Examination Survey in USA. We investigated the association between depressive symptoms (defined as Patient Health Questionnaire 9 scores ≥10) and all-cause and cardiovascular disease (CVD) mortalities, adjusted for multiple factors (sociodemographic in Model 1, behavioral added in Model 2, and metabolic syndrome added in Model 3) and stratified by age and sex. During an average follow-up of 69.15 months (standard deviation [SD] 34.45), 1872 (7.3%) participants had died (person-years in the non-depressive and depressive groups, 12.12/1000 and 16.43/1000, respectively). Depressive symptoms increased all-cause (crude hazard ratio [HR] 1.37, 95% confidence interval [CI], 1.33–1.58) and CVD mortalities (crude HR 1.64, 95% CI, 1.20–2.24). Although the significance of all-cause mortality and CVD mortality was maintained in Models 1 (HR 1.58 and 2.08) and 2 (HR 1.48 and 1.79), it was not maintained in Model 3. Current smoking and lower physical activity were associated with reduced strength of the association between depression and all-cause mortality risk. The effect of depression on mortality risk was particularly pronounced in middle-aged men and older women. Our findings suggest that depressive symptoms increase mortality risk, even after adjusting for behavioral factors. Depression-induced mortality risk is particularly high among middle-aged men and older women. • Depression increased all-cause and cardiovascular disorder mortalities. • Depression increased mortality despite adjusted demographic and behavioral factors. • Smoking and less exercise reduced the association between depression and mortality. • Depression had a greater impact on mortality among middle-aged men and older women. [ABSTRACT FROM AUTHOR]

Introduction: This prospective cohort study investigated the clinical role of circulating tumor necrosis factor receptor (cTNFR) levels as prognostic biomarkers in severe acute kidney injury (AKI) patients requiring continuous renal replacement therapy (CRRT). Methods: We enrolled 136 patients from 7 hospitals participating in the VENUS (VolumE maNagement Under body composition monitoring in critically ill patientS on CRRT) trial from July 2017 to October 2019. The levels of cTNFR1 and cTNFR2 were measured using plasma samples collected on days 0 (D0), 2 (D2), and 7 (D7). Patients were divided into high- and low-cTNFR groups based on their receptor concentrations. Results: D0 concentrations of cTNFR1 and cTNFR2 were positively correlated with one another (R2 = 0.37, p < 0.001). The high-cTNFR1 group displayed a higher in-hospital mortality rate than the low-TNFR1 group (p = 0.002). Moreover, the mortality rate was significantly higher in the high-TNFR1 group than in the low-TNFR1 group after adjusting for age, sex, and acute physiology, and chronic health evaluation II scores (hazard ratio 1.82, 95% confidence interval 1.09–3.03, p = 0.025). D2 and D7 cTNFR1 levels were also associated with in-hospital mortality; contrastingly, cTNFR2 levels were not associated with this outcome. Additionally, patients were divided into three groups according to the change in cTNFR levels from D0 to D2 (ΔcTNFR). Those in the highest ΔcTNFR tertile had a higher mortality rate than the remaining patients (p = 0.033 for ΔcTNFR1; p = 0.025 for ΔcTNFR2). Patients who underwent AKI-to-chronic kidney disease transition had higher concentrations of cTNFR1 (p = 0.014). Discussion/Conclusion: Plasma cTNFR1 concentrations at CRRT initiation and changes in cTNFR1 and 2 levels immediately following CRRT initiation are significant biomarkers for predicting the outcomes of patients with severe AKI. [ABSTRACT FROM AUTHOR]

This study presents a diagnostic plot model to evaluate the injection performance of polymer flooding in a heterogeneous reservoir. To develop the model, comprehensive equation using an analytical method was proposed considering fully-developed cross-flow and saturation distribution due to polymer effects. The developed model was compared with the results from reservoir simulation to verify its accuracy. The comparison indicated that the model yields more accurate results than the other previous methods. Additionally, case studies have been performed to check whether any unexpected geological problem in the reservoir could be detected. From the results, the model can indicate the variation of the injectivity through geological problems such as semi-sealing and permeability improvement. Therefore, the model can provide specific information to improve injectivity and enhance the operational efficiency of polymer flooding. [ABSTRACT FROM AUTHOR]

This study presents an experimental apparatus to investigate the adsorption characteristics in shale samples of two major US basins. The adsorption measurement is based on volumetric method, and the results are analyzed by Langmuir isotherm at various pressures. To analyze the impact of temperature on the adsorption characteristics, the experiments were conducted on the samples. The experimental results revealed that the change of adsorption capacity became constant with the increase of pressure and the decrease of adsorption capacity was dependent on the increase of temperature. This study allows us to evaluate shale gas in place and production forecast through adsorption characteristics. [ABSTRACT FROM AUTHOR]

Comprehensive studies on wormhole prediction models have been performed to design successful matrix acidizing in carbonate reservoirs. In particular, linear coreflooding experiments have been extensively conducted to predict the optimum injection rate of various acid types under reservoir conditions. Currently, the optimum injection rates are obtained by fitting the linear core-flooding experiment results using a semiempirical model; however, the wormhole propagation behavior has not been considered. This study develops an improved wormhole prediction model to estimate the optimum injection rate and wormhole velocity considering the propagation characteristics of wormhole heads, which is derived by wormhole visualization with Xray computerized tomography (CT). 5 cases comprising 25 linear core-flooding experiments are conducted to determine the optimum injection rates under different acid concentrations and permeabilities. In addition, wormhole visualization is performed using high-resolution X-ray CT to analyze the propagation characteristics of wormhole heads. To validate the improved model, the experimental results of coreflooding are matched with the fitting curves of the improved model and previous model. Furthermore, the absolute average percentage error (AAPE) is obtained to estimate the fitting accuracy of the improved model and previous model. From the results, the AAPE of the improved model was remarkably lower than those of the previous model, confirming that the new model can perform the more preferable prediction of wormhole propagation than the previous model. Finally, the optimum injection rate and the optimum wormhole velocity () are determined using the new model and previous model. The optimum injection rates derived using the new model were lower thanthose of the previous model, but the values obtained by the new model were higher than those of the previous model. It is believed that the lower pump rate may result from the lower optimum injection rate with a faster optimum wormhole velocity. Therefore, a less acid consumption owing to the lower pump rate would be required to create the optimum wormhole approaching the targeted distance from the well to damaged zone for the stimulation. In conclusion, a more economical design of the carbonate acidizing is possible by determining the optimum injection rate for the new model compared to the previous model. • The fitting curve of the new model showed more decent matching to the experimental results. • The new model can conduct a more preferable prediction of the wormhole propagation. • The less acid consumption owing to the lower pump rate would be required to create the optimum wormhole. • Economical design of the carbonate acidizing would be available through the new model. [ABSTRACT FROM AUTHOR]

In patients with chronic kidney disease (CKD), coronavirus disease 2019 (COVID-19) has a higher mortality rate than the general population; therefore, prevention is vital. To prevent COVID-19 infection, it is important to study individuals' risk aversion behavior. The objective of this study was to understand how the behavioral characteristics of physical distancing, hygiene practice, and exercise changed in patients with CKD during the COVID-19 pandemic and to identify the characteristics of patients who showed weakened or strengthened behavioral changes. We analyzed data from the Study on Kidney Disease and Environmental Chemicals (Clinical Trial No. NCT04679168), that examined a prospective cohort of patients with CKD. This cohort included patients with CKD who visited the participating hospitals for the first time between June and October 2020 and the second time between October 2020 and January 2021. Data on demographics, socio-economic details, and behavioral characteristics were collected through a questionnaire survey. Using a multivariable logistic regression model, we identified whether COVID-19 infection risk perception and previous strong behavioral changes affected behavioral changes during the first and second visits. A total of 277 patients (33.2% females) were included in the analysis. Nine out of 12 behaviors were reinforced at the first visit, and five out of nine reinforced behaviors were weakened at the second visit. A high-risk perception of COVID-19 infection was not associated with the tendency of overall behavioral reinforcement or maintaining behaviors in an enhanced state at the second visit. Strong behavioral changes at the patients' first visit to the hospital were associated with a tendency to strengthen or maintain reinforced behaviors at the second visit (adjusted odds ratio 1.99, 95% confidence interval 1.19–3.34; P = 0.009). Even if the initial COVID-19 risk perception is high, behavioral changes worsen over time. Individuals who showed more active behavioral changes at the beginning of the COVID-19 pandemic tended to maintain reinforced behavior over time. Continuous education and monitoring are needed to maintain changed behaviors, especially in patients with a high initial COVID-19 risk perception. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate the diffusion characteristics of nanoscale gas flow in a shale gas reservoir. An experimental apparatus was designed and set up to measure porosity and permeability at the nanopore scale. The measured properties have been used to determine a diffusion coefficient by classification standard of gas flow regime. To investigate the impact of pressure and pore size, the analysis of diffusion flow was conducted using Knudsen and Fick diffusion coefficients. From the results, it was revealed that Knudsen diffusion coefficient gradually increased with the growth of pressure and pore radius and Fick diffusion coefficient was dependent on the gas molecular diameter and temperature. It was also found that Knudsen diffusion coefficient was equal to Fick diffusion coefficient if pore radius is too small. The study implied that the characteristics of gas diffusion should be implemented by using the diffusion coefficient theory based on gas flow regime in shale gas reservoirs. [ABSTRACT FROM AUTHOR]

Despite interest in the clinical implications of soluble transferrin receptor (sTfR), previous studies on the association of sTfR with mortality in the general population are lacking. Therefore, we analysed the association between sTfR and all-cause mortality in the general United States adult population. We conducted a prospective cohort study using National Health and Nutrition Examination Survey data from 2003 to 2010. A total of 5403 premenopausal nonpregnant females were analysed in this study. The mean age was 34.2 years (range 20.0–49.9 years). Participants were divided into log(sTfR) tertiles. The primary outcome was all-cause mortality. The secondary outcome was chronic kidney disease (CKD) development (composite of estimated glomerular filtration rate < 60 ml/min/1.73 m2 and/or random urine albumin-to-creatinine ratio ≥ 30 mg/g). During a median 8.7 years of follow-up, 103 (1.9%) participants died. Compared with the reference group (log(sTfR) 0.45–0.57), the highest tertile of log(sTfR) was associated with all-cause mortality (log(sTfR) > 0.57, hazard ratio [HR] 1.77 [95% CI 1.05–2.98]) in a multivariable hazards model including covariates such as haemoglobin and ferritin. Patients in the highest tertile of log(sTfR) also had an increased risk of CKD relative to those in the reference tertile. High sTfR was associated with all-cause mortality and CKD regardless of anaemia and iron storage status. [ABSTRACT FROM AUTHOR]

The association between increased red blood cell distribution width (RDW) and mortality among patients treated on an outpatient basis in the nephrology outpatient clinic is unclear. Therefore, our study aimed to investigate the association between baseline and time-averaged RDW and mortality risk in patients treated in our nephrology outpatient clinic. Our multi-center retrospective analysis was based on data of 16,417 outpatient nephrology patients with available baseline renal function and RWD values. The median baseline RDW was 13.0% (range, 10.0–32.1%). The high-RDW group was defined as the top quartile (≥ 13.8%, n = 4302). The crude mortality rate was 15.0% (n = 1806) at a median follow-up of 127.5 months. From the results of the multivariate Cox proportional hazards regression model adjusted for covariates, including eGFR, hemoglobin, and factors of anemia treatment, patients with a high time-averaged RDW had increased mortality risk (adjusted hazard ratio, 1.505; 95% confidence interval, 1.326–1.708; P < 0.001), irrespective of sex, presence of anemia, and chronic kidney disease, except in individuals aged < 45 years. Thus, increased baseline and time-averaged RDW were significantly associated with increased mortality in patients aged > 45 years treated on an outpatient basis in the nephrology clinic. [ABSTRACT FROM AUTHOR]

Large-scale studies have not been conducted to assess whether serum hypobicarbonatemia increases the risk for kidney function deterioration and mortality among East-Asians. We aimed to determine the association between serum total CO2 (TCO2) concentrations measured at the first outpatient visit and clinical outcomes. In this multicenter cohort study, a total of 42,231 adult nephrology outpatients from 2001 to 2016 were included. End-stage renal disease (ESRD) patients on dialysis within 3 months of the first visit were excluded. Instrumental variable (IV) was used to define regions based on the proportion of patients with serum TCO2 < 22 mEq/L. The crude mortality rate was 12.2% during a median 77.0-month follow-up period. The Cox-proportional hazard regression model adjusted for initial kidney function, alkali supplementation, and the use of diuretics demonstrated that low TCO2 concentration was not associated with progression to ESRD, but significantly increased the risk of death. The IV analysis also confirmed a significant association between initial TCO2 concentration and mortality (HR 0.56; 95% CI 0.49–0.64). This result was consistently significant regardless of the underlying renal function. In conclusion, low TCO2 levels are significantly associated with mortality but not with progression to ESRD in patients with ambulatory care. [ABSTRACT FROM AUTHOR]

Predicting the risk of end-stage renal disease (ESRD) progression facilitates appropriate nephrology care of patients with chronic kidney disease (CKD). Previously, the kidney failure risk equations (KFREs) were developed and validated in several cohorts. The purpose of this study is to validate the KFREs in a Korean population and to recalibrate the equations. A total of 38,905 adult patients, including 13,244 patients with CKD stages G3–G5, who were referred to nephrology were recruited. Using the original KFREs (4-, 6- and 8-variable equations) and recalibration equations, we predicted the risk of 2- and 5-year ESRD progression. All analyses were conducted in CKD stages G3-G5 patients as well as the total population. In CKD stages G3–G5 patients, All the original 4-, 6- and 8-variable equations showed excellent areas under the receiver operating characteristic curve of 0.87 and 0.83 for the 2- and 5-year risk of ESRD, respectively. The results of net reclassification improvement, integrated discrimination index and Brier score showed that recalibration improved the prediction models in some cases. The original KFREs showed high discrimination in both CKD stages G3–G5 patients and the total population referred to nephrology in this large Korean cohort. KFREs can be implemented in Korean health systems and can guide nephrology referrals and other CKD-related treatment decisions. [ABSTRACT FROM AUTHOR]

Objective: Metformin is the first pharmacological option for treating type 2 diabetes. However, the use of this drug is not recommended in individuals with impaired kidney function because of the perceived risk of lactic acidosis. We aimed to assess the efficacy and safety of metformin in patients with type 2 diabetic kidney disease (DKD).Research Design and Methods: We conducted a retrospective observational cohort study of 10,426 patients with type 2 DKD from two tertiary hospitals. The primary outcomes were all-cause mortality and end-stage renal disease (ESRD) progression. The secondary outcome was metformin-associated lactic acidosis. Taking into account the possibility that patients with less severe disease were prescribed metformin, propensity score matching (PSM) was conducted.Results: All-cause mortality and incident ESRD were lower in the metformin group according to the multivariate Cox analysis. Because the two groups had significantly different baseline characteristics, PSM was performed. After matching, metformin usage was still associated with lower all-cause mortality (adjusted hazard ratio [aHR] 0.65; 95% CI 0.57-0.73; P < 0.001) and ESRD progression (aHR 0.67; 95% CI 0.58-0.77; P < 0.001). Only one event of metformin-associated lactic acidosis was recorded. In both the original and PSM groups, metformin usage did not increase the risk of lactic acidosis events from all causes (aHR 0.92; 95% CI 0.668-1.276; P = 0.629).Conclusions: In the present retrospective study, metformin usage in advanced chronic kidney disease (CKD) patients, especially those with CKD 3B, decreased the risk of all-cause mortality and incident ESRD. Additionally, metformin did not increase the risk of lactic acidosis. However, considering the remaining biases even after PSM, further randomized controlled trials are needed to change real-world practice. [ABSTRACT FROM AUTHOR]

• MICP and acid-rock reaction experiments were conducted using four types of limestones. • Correlation analysis between diffusion coefficient and pore size distribution was performed. • Pore size distribution shows better correlations with diffusion coefficient than porosity and permeability. • Optimum injection rate has a high relevance to pore size distribution because of diffusion coefficient. • Pore size distribution should be considered to design optimum injection conditions. This study presents the correlation analysis between pore size distribution and diffusion coefficient based on the experimental results to evaluate the effect of pore size distribution on the acid-rock reaction in carbonate acidizing. The mercury injection capillary pressure (MICP) was used to analyze the pore size distribution of four limestone samples. Also, the acid-rock reaction experiments were conducted to measure diffusion coefficients using rotating disk apparatus (RDA). In the experimental results, micropore dominated rock samples have lower dissolution rate and diffusion coefficient than macropore dominated rock samples. It is obviously revealed that the dissolution rate and diffusion coefficient for limestone samples with similar mineral compositions are quite different due to various pore size distribution. In the result of correlation analysis, it is revealed that neither porosity nor permeability exhibits a strong correlation with diffusion coefficient compared with pore size distribution. Therefore, it can imply that the petro-physical properties such as porosity and permeability have a lower relevance to the acid-rock reaction kinetics than pore size distribution. To investigate the effect of pore size distribution on matrix acidizing, optimum injection rates were derived by the experimental results. As a result, the optimum injection rates increase with the mean and median pore size, and the micropore dominated rock samples show lower optimum injection rate than the macropore dominated rock samples. Although the pore size distribution shows a strong correlations with matrix acidizing, the optimum injection rate has been estimated without ample considerations of pore size distribution. Therefore, the effect of pore size distribution on diffusion coefficient should be considered to design the optimum injection conditions in carbonate acidizing job. [ABSTRACT FROM AUTHOR]

Chemicals have been identified as a potential risk factor of renal dysfunction. However, studies that consider both multiple chemicals and non-chemical risk factors, such as hypertension, are rare. In this study, we assessed the associations between exposure to several chemicals, including major metals, phthalates, and phenolic compounds, and the albumin-to-creatinine ratio (ACR). A group of Korean adult women in reproductive age (n = 438, aged between 20 and 49 years), who had previously been studied for association of several organic chemicals, was chosen for this purpose. We constructed multivariable linear regression models for individual chemicals and weighted-quantile sum (WQS) mixtures, by hypertension status. Among the study population, approximately 8.5% of the participants exhibited micro/macro-albuminuria (ACR ≥30 mg/g), and 18.5% and 3.9% exhibited prehypertension and hypertension, respectively. Blood cadmium and lead levels showed a stronger association with ACR only among women with prehypertension or hypertension. Among organic chemicals, depending on the statistial model, benzophenone-1 (BP-1) and mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) showed a significant association regardless of hypertension status, but most associations disappeared in the (pre)hypertensive group. These findings clearly indicate that hypertension status can modify and may potentiate the association of environmental chemicals with ACR. Our observations suggest that low-level environmental pollutant exposure may have potential adverse effects on kidney function among general adult women. Considering the prevalence of prehypertension in the general population, efforts to reduce exposure to cadmium and lead are necessary among adult women to minimize the risk of adverse kidney function. • Blood metals and urinary organic compounds in adult women were associated with ACR. • Cadmium & lead were associated with ACR only in (pre)hypertensive women. • Associations of BP-1 & MEHHP remained significant regardless of hypertension status. • The mitigation of metal exposure is more important among women with (pre)hypertension. [ABSTRACT FROM AUTHOR]

Abstract Chronic kidney disease (CKD) is a global health threat of growing concern. Recently, exposure to endocrine disrupting compounds (EDCs) such as phthalates and bisphenol A has been suggested as a risk factor for CKD. However, most epidemiological studies have focused on a limited number of urinary chemicals. This study aimed to identify chemical determinants of the urinary albumin-to-creatinine ratio (ACR), which is a kidney function marker, among multiple major EDCs including phthalate metabolites, bisphenols, and benzophenones in a Korean female population (20–45 years old, n = 441). First, the creatinine-adjusted urinary concentration of each urinary chemical was associated with ACR in a linear regression model (single-pollutant model). Then, compounds with a significant association with ACR in the single-pollutant model were added in a multi-pollutant model and evaluated for their association with ACR. Moreover, to prevent potential reverse causality due to impaired kidney function, quartile analyses were performed for the subjects with healthy renal function (ACR < 9.71 mg/g). In addition to creatinine adjustment, the statistical analysis was also conducted with specific gravity-adjusted concentrations of urinary chemicals, and the results were compared. Several compounds measured in the urine showed a significant association with ACR in the single-pollutant model. In the multi-pollutant model, however, only monobutyl phthalate and benzophenone-1, which are metabolites of dibutyl phthalate and benzophenone-3, respectively, showed significant positive associations. The association of these chemicals remained significant in a couple of the sensitivity analyses with a different adjustment of urine dilution and in a subpopulation with normal ACR. In conclusion, among dozens of urinary chemicals, monobutyl phthalate and benzophenone-1 consistently showed a strong association with urinary ACR. Confirmation of our observation in other human populations and experimental studies is warranted. Highlights • Multiple urinary compounds were associated with ACR among healthy adult female. • For the first time, association of benzophenones with kidney function was observed. • MBP, a metabolite of DBP, also consistently showed strong association with ACR. • Association of bisphenol A and DEHP with ACR was not obvious. [ABSTRACT FROM AUTHOR]

Abstract Due to the increased availability of digital human models, the need for knowing human movement is important in product design process. If the human motion is derived rapidly as design parameters change, a developer could determine the optimal parameters. For example, the optimal design of the door panel of an automobile can be obtained for a human operator to conduct the easiest ingress and egress motion. However, acquiring motion data from existing methods provides only unrealistic motion or requires a great amount of time. This not only leads to an increased time consumption for a product development, but also causes inefficiency of the overall design process. To solve such problems, this research proposes an algorithm to rapidly and accurately predict full-body human motion using an artificial neural network (ANN) and a motion database, as the design parameters are varied. To achieve this goal, this study refers to the processes behind human motor learning procedures. According to the previous research, human generate new motion based on past motion experience when they encounter new environments. Based on this principle, we constructed a motion capture database. To construct the database, motion capture experiments were performed in various environments using an optical motion capture system. To generate full-body human motion using this data, a generalized regression neural network (GRNN) was used. The proposed algorithm not only guarantees rapid and accurate results but also overcomes the ambiguity of the human motion objective function, which has been pointed out as a limitation of optimization-based research. Statistical criteria were utilized to confirm the similarity between the generated motion and actual human motion. Our research provides the basis for a rapid motion prediction algorithm that can include a variety of environmental variables. This research contributes to an increase in the usability of digital human models, and it can be applied to various research fields. [ABSTRACT FROM AUTHOR]

Abstract: Aim: This study aimed to explore the trends in individual income and to estimate the change in average monthly income for patients undergoing haemodialysis therapy. Methods: The main data source was the Clinical Research Center (CRC) for End‐Stage Renal Disease in Korea. In addition to the cohort data, a survey was conducted to capture personal income for 3 years. To estimate the change in monthly income over time using repeated measures, a random coefficient model using penalized quasi‐likelihood methods based on restricted or residual maximum likelihood estimation was used. Results: During the 3‐year study period, 138 subjects aged 20 and over who answered the question about pre‐dialysis income were traced and analyzed. The median value of monthly income was $US564.4 in the 1st year, $470.4 in the 2nd year, and $733.8 in the 3rd year, representing a 70%, 75%, and 61% decrease compared to pre‐dialysis income ($1881.5), respectively. By using mixed analysis, we found that monthly income change was $1283 (95% CI, −1621.5, −945.1), $1182 USD (95% CI, −1540.8, −823.1), and $1041 (95% CI, −1457.6, −623.6) in the 1st, 2nd, and 3rd year, respectively, compared to pre‐dialysis income after controlling for other covariates. Women and less educated patients had a relatively higher reduction of income, despite the low starting point. Conclusions: The monthly income of dialysis patients reduced substantially over the study period, especially at the time of the first survey. Considering the social security system, haemodialysis patients face significant personal financial burdens due to their ESRD unrelated to the direct costs of dialysis treatment. [ABSTRACT FROM AUTHOR]