Compressible lattice Boltzmann method with rotating overset grids

The numerical instability of the lattice Boltzmann method (LBM) at high Mach or high Reynolds number flow is well identified, and it remains a major barrier to its application in more complex configurations such as moving geometries. This work combines the compressible lattice Boltzmann model with rotating overset grids (the so-called Chimera method, sliding mesh, or moving reference frame) for high Mach flows. This paper proposes to use the compressible hybrid recursive regularized collision model with fictitious forces (or inertial forces) in a noninertial rotating reference frame. Also, polynomial interpolations are investigated, which allow fixed inertial and rotating noninertial grids to communicate with each other. We suggest a way to effectively couple the LBM with the MUSCL-Hancock scheme in the rotating grid, which is needed to account for thermal effect of compressible flow. As a result, this approach is demonstrated to have an extended Mach stability limit for the rotating grid. It also demonstrates that this complex LBM scheme can maintain the second-order accuracy of the classic LBM by appropriately using numerical methods like polynomial interpolations and the MUSCL-Hancock scheme. Furthermore, the method shows a very good agreement on aerodynamic coefficients compared to experiments and the conventional finite-volume scheme. This work presents a thorough academic validation and error analysis of the LBM for simulating moving geometries in high Mach compressible flows.

Associations among depression, demographic variables, and language impairments in chronic post-stroke aphasia

INTRODUCTION

Depression may influence treatment participation and outcomes of people with post-stroke aphasia, yet its prevalence and associated characteristics in aphasia are poorly understood. Using retrospective data from an overarching experimental study, we examined depressive symptoms and their relationship to demographic and language characteristics in people with chronic aphasia. As a secondary objective, we compared prevalence of depressive symptoms among the overarching study's included and excluded participants.

METHODS

We examined retrospective data from 121 individuals with chronic aphasia including depression scale scores, demographic information (sex, age, time post onset of stroke, education, race/ethnicity, and Veteran status), and scores on assessments of general and modality-specific language impairments.

RESULTS

Approximately 50% of participants reported symptoms indicative of depressive disorders: 23% indicative of major depression and 27% indicative of mild depression. Sex (males) and comparatively younger age emerged as statistically significant variables associated with depressive symptoms; naming ability was minimally associated with depressive symptoms. Time post onset of stroke, education level, race/ethnicity, Veteran status, and aphasia severity were not significantly associated with depressive symptoms. Depression-scale scores were significantly higher for individuals excluded from the overarching study compared to those who were included.

CONCLUSIONS

The rate of depressive disorders in this sample was higher than rates of depression reported in the general stroke literature. Participant sex, age, and naming ability emerged as factors associated with depressive symptoms, though these links appear complex, especially given variable reports from prior research. Importantly, depressive symptoms do not appear to diminish over time for individuals with chronic aphasia. Given these results and the relatively limited documentation of depression in aphasia literature, depression remains a pressing concern for aphasia research and routine clinical care.

The microrandomized trial for developing digital interventions: Experimental design and data analysis considerations

Just-in-time adaptive interventions (JITAIs) are time-varying adaptive interventions that use frequent opportunities for the intervention to be adapted-weekly, daily, or even many times a day. The microrandomized trial (MRT) has emerged for use in informing the construction of JITAIs. MRTs can be used to address research questions about whether and under what circumstances JITAI components are effective, with the ultimate objective of developing effective and efficient JITAI. The purpose of this article is to clarify why, when, and how to use MRTs; to highlight elements that must be considered when designing and implementing an MRT; and to review primary and secondary analyses methods for MRTs. We briefly review key elements of JITAIs and discuss a variety of considerations that go into planning and designing an MRT. We provide a definition of causal excursion effects suitable for use in primary and secondary analyses of MRT data to inform JITAI development. We review the weighted and centered least-squares (WCLS) estimator which provides consistent causal excursion effect estimators from MRT data. We describe how the WCLS estimator along with associated test statistics can be obtained using standard statistical software such as R (R Core Team, 2019). Throughout we illustrate the MRT design and analyses using the HeartSteps MRT, for developing a JITAI to increase physical activity among sedentary individuals. We supplement the HeartSteps MRT with two other MRTs, SARA and BariFit, each of which highlights different research questions that can be addressed using the MRT and experimental design considerations that might arise. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Effect of Metal-Precursor Stacking Order on Volume-Defect Formation in CZTSSe Thin Film: Formation Mechanism of Blisters and Nanopores

In this study, we investigated the effect of the stacking order of metal precursors on the formation of volume defects, such as blisters and nanopores, in CZTSSe thin-film solar cells. We fabricated CZTSSe thin films using three types of metal-precursor combinations, namely, Zn/Cu/Sn/Mo, Cu/Zn/Sn/Mo, and Sn/Cu/Zn/Mo, and studied the blister formation. The blister-formation mechanism was based on the delamination model, taking into consideration the compressive stress and adhesion properties. A compressive stress could be induced during the preferential formation of a ZnSSe shell. Under this stress, the adhesion between the ZnSSe film and the Mo substrate could be maintained by the surface tension of a metallic liquid phase with good wettability, or by the functioning of ZnSSe pillars as anchors, depending on the type of metal precursor used. Additionally, the nanopore formation near the back-contact side was found to be induced by the columnar microstructure of the metal precursor with the Cu/Zn/Mo stacking order and its dezincification. Based on the two volume-defect-formation mechanisms proposed herein, further development of volume-defect-formation suppression technology is expected to be made.

Estimating time-varying causal excursion effect in mobile health with binary outcomes

Advances in wearables and digital technology now make it possible to deliver behavioral mobile health interventions to individuals in their everyday life. The micro-randomized trial is increasingly used to provide data to inform the construction of these interventions. In a micro-randomized trial, each individual is repeatedly randomized among multiple intervention options, often hundreds or even thousands of times, over the course of the trial. This work is motivated by multiple micro-randomized trials that have been conducted or are currently in the field, in which the primary outcome is a longitudinal binary outcome. The primary aim of such micro-randomized trials is to examine whether a particular time-varying intervention has an effect on the longitudinal binary outcome, often marginally over all but a small subset of the individual's data. We propose the definition of causal excursion effect that can be used in such primary aim analysis for micro-randomized trials with binary outcomes. Under rather restrictive assumptions one can, based on existing literature, derive a semiparametric, locally efficient estimator of the causal effect. Starting from this estimator, we develop an estimator that can be used as the basis of a primary aim analysis under more plausible assumptions. Simulation studies are conducted to compare the estimators. We illustrate the developed methods using data from the micro-randomized trial, BariFit. In BariFit, the goal is to support weight maintenance for individuals who received bariatric surgery.

Provider Care Team Segregation and Operative Mortality Following Coronary Artery Bypass Grafting

BACKGROUND

Studies have shown that Black patients die more frequently following coronary artery bypass grafting than their White counterparts for reasons not fully explained by disease severity or comorbidity. To examine whether provider care team segregation within hospitals contributes to this inequity, we analyzed national Medicare data.

METHODS

Using national Medicare data, we identified beneficiaries who underwent coronary artery bypass grafting at hospitals where this procedure was performed on at least 10 Black and 10 White patients between 2008 and 2014 (n=12 646). After determining the providers who participated in their perioperative care, we examined the extent to which Black and White patients were cared for by unique networks of provider care teams within the same hospital. We then evaluated whether a lack of overlap in composition of the provider care teams treating Black versus White patients (ie, high segregation) was associated with higher 90-day operative mortality among Black patients.

RESULTS

The median level of provider care team segregation was high (0.89) but varied across hospitals (interquartile range, 0.85-0.90). On multivariable analysis, after controlling for patient-, hospital-, and community-level differences, mortality rates for White patients were comparable at hospitals with high and low levels of provider care segregation (5.4% [95% CI, 4.7%-6.1%] versus 5.8% [95% CI, 4.7%-7.0%], respectively; P=0.601), while Black patients treated at high-segregation hospitals had significantly higher mortality than those treated at low-segregation hospitals (8.3% [95% CI, 5.4%-12.4%] versus 3.3% [95% CI, 2.0%-5.4%], respectively; P=0.017). The difference in mortality rates for Black and White patients treated at low-segregation hospitals was nonsignificant (-2.5%; P=0.098).

CONCLUSIONS

Black patients who undergo coronary artery bypass grafting at a hospital with a higher level of provider care team segregation die more frequently after surgery than Black patients treated at a hospital with a lower level.

Influence of the Reaction Pathway on the Defect Formation in a Cu2ZnSnSe4 Thin Film

Point defect engineering in Cu₂ZnSnSe₄ (CZTSe) thin films is the main issue to improve its device performance. This study reveals the correlation between the reaction pathway and the point defects in the CZTSe film. The reaction pathway from a metallic precursor (Mo/Zn/Sn/Cu) to a kesterite CZTSe film is varied by changing the annealing process. The synthesized CZTSe films under different reaction pathways induce different device performances with different defect energy levels, although all CZTSe films have similar structural and optical properties (E_g ∼ 1.0 eV). The admittance spectroscopy demonstrates the correlations between point defect types (V_Zn, Zn_Sn, Zn_Cu, Cu_Zn, and V_Cu) and the reaction pathways for the formation of CZTSe films. The different growth rates of binary selenides, such as ZnSe and/or Sn-Se phases, during the annealing process are especially strongly related to the formation of point defects, leading to the different open-circuit voltages (396-451 mV) and fill factors (51-65%). The results of this study suggest that controlling the reaction pathway is an effective approach to adjust the formation of defects in the kesterite CZTSe film as well as to fabricate high-performance solar cell devices.

A Facile Process for Partial Ag Substitution in Kesterite Cu2ZnSn(S,Se)4 Solar Cells Enabling a Device Efficiency of over 12

A cation substitution in Cu₂ZnSn(S,Se)₄ (CZTSSe) offers a viable strategy to reduce the open-circuit voltage (V_oc)-deficit by altering the characteristics of band-tail states, antisite defects, and related defect clusters. Herein, we report a facile single process, i.e., simply introducing a thin Ag layer on a metallic precursor, to effectively improve the device characteristics and performances in kesterite (Ag_x,Cu_1-x)₂ZnSn(S_y,Se_1-y)₄ (ACZTSSe) solar cells. Probing into the relationship between the external quantum efficiency derivative (dEQE/dλ) and device performances revealed the V_oc-deficit characteristics in the ACZTSSe solar cells as a function of Cu and Ag contents. The fabricated champion ACZTSSe solar cell device showed an efficiency of 12.07% and a record low V_oc-deficit of 561 mV. Thorough investigations into the mechanism underpinning the improved performance in the ACZTSSe device further revealed the improved band-tailing characteristic, effective minority carrier lifetime, and diode factors as well as reduced antisite defects and related defect clusters as compared to the CZTSSe device. This study demonstrates the feasibility of effectively suppressing antisite defects, related defect clusters, and band-tailing characteristics by simply introducing a thin Ag layer on a metallic precursor in the kesterite solar cells, which in turn effectively reduces the V_oc-deficit.

Achieving Low VOC-deficit Characteristics in Cu2ZnSn(S,Se)4 Solar Cells through Improved Carrier Separation

Kesterite-based thin-film solar cells (TFSCs) have recently gained significant attention in the photovoltaic (PV) sector for their elemental earth abundance and low toxicity. An inclusive study from the past reveals basic knowledge about the grain boundary (GB) and grain interior (GI) interface. However, the compositional dependency of the surface potential within GBs and GIs remains unclear. The present work provides insights into the surface potential of the bulk and GB interfaces. The tin (Sn) composition is sensitive to the absorber morphology, and therefore, it significantly impacts absorber and device properties. The absorber morphology improves with the formation of larger grains as the Sn content increases. Additionally, the presence of Sn(S,Se)₂ and increased [Zn_Cu + V_Cu] A-type defect cluster density are observed, validated through Raman analysis. The secondary ion mass spectroscopy analysis reveals the altered distribution of sulfur (S) and sodium (Na) with higher near-surface accumulation. The synergistic outcome of the increased density of defects and the accumulation of S near the interface provides a larger GB and GI difference and expedites carrier separation improvement. Consequently, at an optimum compositional ratio of Cu/(Zn+Sn) = ∼0.6, the power conversion efficiency (PCE) is significantly improved from 6.42 to 11.04% with a record open-circuit voltage (V_OC) deficit of 537 mV.

Uncovering Biological Factors That Regulate Hepatocellular Carcinoma Growth Using Patient-Derived Xenograft Assays

BACKGROUND AND AIMS

Several major factors limit our understanding of hepatocellular carcinoma (HCC). First, human HCCs are infrequently biopsied for diagnosis and thus are not often biologically interrogated. Second, HCC initiation and progression are strongly influenced by the cirrhotic microenvironment, and the exact contributions of intrinsic and extrinsic tumor factors are unclear. A powerful approach to examine the personalized biology of liver cancers and the influence of host tissues is with patient-derived xenograft (PDX) models. In Asia, HCCs from patients with hepatitis B virus have been efficiently converted into PDXs, but few parallel efforts from the west have been reported.

APPROACH AND RESULTS

In a large-scale analysis, we implanted 93 HCCs and 8 cholangiocarcinomas (CCAs) to systematically analyze host factors and to define an optimized platform for PDX development from both surgical and biopsy samples. NOD Scid IL-2Rγ^-/- (NSG) mice that had undergone partial hepatectomy (PHx) represented the best combination of engraftability, growth, and passageability, but overall rates were low and indicative of a unique intrinsic biology for HCCs in the United States. PDX models preserved the histology and genetic features of parental tumors, and ultimately, eight models were usable for preclinical studies. Intriguingly, HCC PDXs were differentially sensitive to regorafenib and sorafenib, and CCA PDXs were also highly sensitive to regorafenib.

CONCLUSIONS

PDX models functionalize early and advanced stage HCCs and revealed unique biological features of liver cancers from the United States.

Early cidofovir administration might be associated with a lower probability of respiratory failure in treating human adenovirus pneumonia: a retrospective cohort study

Objective

To compare outcomes of early and delayed treatment with cidofovir for human adenovirus (HAdV) pneumonia.

Methods

A retrospective cohort study in Korean military hospitals was conducted between January 2012 and December 2018. Patients with potentially severe HAdV pneumonia with risk factors for respiratory failure were included and divided into early (within 7 days from symptom onset) and delayed (after 7 days from symptom onset) treatment groups. The primary outcome was respiratory failure development within 21 days after symptom onset.

Results

A total of 89 patients with potentially severe HAdV pneumonia were enrolled in the cohort; they included 62 early and 27 delayed treatment patients. All patients were males in their early 20s. Significantly fewer patients in the early treatment group progressed to respiratory failure (8/62, 12.9%), compared to the delayed group (18/27, 66.7%, p < 0.001). Early treatment was associated with a lower 21-day probability of respiratory failure by the Kaplan–Meier method (p < 0.001). On multivariate analysis, monocyte count, hypoxaemia, confusion, whole lung involvement, and early cidofovir treatment within 7 days from symptom onset were included, and monocyte count (HR 0.995, 95%CI 0.991–1.000, p 0.042), confusion (HR 4.964, 95%CI 1.189–20.721, p = 0.028), and early cidofovir treatment (HR 0.319, 95%CI 0.115–0.883, p = 0.028) were significantly associated with respiratory failure.

Conclusions

Early administration of cidofovir was associated with a lower hazard for respiratory failure development. It is suggested that cidofovir be administered within 7 days from symptom onset to prevent respiratory failure in patients with potentially severe HAdV pneumonia.

Photonic crystals for nano-light in moiré graphene superlattices

Graphene is an atomically thin plasmonic medium that supports highly confined plasmon polaritons, or nano-light, with very low loss. Electronic properties of graphene can be drastically altered when it is laid upon another graphene layer, resulting in a moiré superlattice. The relative twist angle between the two layers is a key tuning parameter of the interlayer coupling in thus-obtained twisted bilayer graphene (TBG). We studied the propagation of plasmon polaritons in TBG by infrared nano-imaging. We discovered that the atomic reconstruction occurring at small twist angles transforms the TBG into a natural plasmon photonic crystal for propagating nano-light. This discovery points to a pathway for controlling nano-light by exploiting quantum properties of graphene and other atomically layered van der Waals materials, eliminating the need for arduous top-down nanofabrication.

Helical pitch-dependent electro-optics of optically high transparent nano-phase separated liquid crystals

Feeble light leakage in a dark state of conventional optically isotropic liquid crystal (OILC) device has a strong impact on the contrast ratio of a liquid crystal (LC) device. In order to overcome such intrinsic problem, we proposed an OILC in which the LC directors inside droplets are twisted by introducing chirality. The light leakage is effectively suppressed by matching the refractive indices between LC and polymer matrix; consequently, we achieved a high contrast ratio, 1:1401. Interestingly, the on-state transmittance is enhanced by ~49% compared to conventional OILC. The response time was also improved and the hysteresis was suppressed to be negligible. The improved electro-optic performances of the proposed OILC device would give diverse applications in upcoming flexible display and various photonic devices.

Longitudinal cortical thinning and cognitive decline in patients with early- versus late-stage subcortical vascular mild cognitive impairment

BACKGROUND AND PURPOSE

Biomarker changes in cognitively impaired patients with small vessel disease are largely unknown. The rate of amyloid/lacune progression, cortical thinning and cognitive decline were evaluated in subcortical vascular mild cognitive impairment (svMCI) patients.

METHODS

Seventy-two svMCI patients were divided into early stage (ES-svMCI, n = 39) and late stage (LS-svMCI, n = 33) according to their Clinical Dementia Rating Sum of Boxes score. Patients were annually followed up with neuropsychological tests and brain magnetic resonance imaging for 3 years, and underwent a second [¹¹ C] Pittsburgh compound B (PiB) positron emission tomography scan within a mean interval of 32.4 months.

RESULTS

There was no difference in the rate of increase in PiB uptake or lacune number between the ES-svMCI and LS-svMCI. However, LS-svMCI showed more rapid cortical thinning and cognitive decline than did the ES-svMCI.

CONCLUSIONS

We suggest that, whilst the rate of change in pathological burden did not differ between ES-svMCI and LS-svMCI, cortical thinning and cognitive decline progressed more rapidly in the LS-svMCI.

Multipoint scanning dual-detection confocal microscopy for fast 3D volumetric measurement

We propose a multipoint scanning dual-detection confocal microscopy (MS-DDCM) system for fast 3D volumetric measurements. Unlike conventional confocal microscopy, MS-DDCM can accomplish surface profiling without axial scanning. Also, to rapidly obtain 2D images, the MS-DDCM employs a multipoint scanning technique, with a digital micromirror device used to produce arrays of effective pinholes, which are then scanned. The MS-DDCM is composed of two CCDs: one collects the conjugate images and the other collects nonconjugate images. The ratio of the axial response curves, measured by the two detectors, provides a linear relationship between the height of the sample surface and the ratio of the intensity signals. Furthermore, the difference between the two images results in enhanced contrast. The normalising effect of the MS-DDCM provides accurate sample heights, even when the reflectance distribution of the surface varies. Experimental results confirmed that the MS-DDCM achieved high-speed surface profiling with improved image contrast capability.

Monitoring rate and predictability of intraoperative monitoring in patients with intradural extramedullary and epidural metastatic spinal tumors

STUDY DESIGN

Single-center retrospective study.

OBJECTIVES

To evaluate the monitoring rate, sensitivity and specificity of intraoperative monitoring (IOM) during removal of intradural extramedullary (IDEM) or epidural metastatic spinal tumors. Also, to assess the efficacy of monitoring somatosensory-evoked potentials (SSEP) when motor-evoked potentials (MEP) are not measurable.

SETTING

The Neuro-Oncology Clinic, National Cancer Center, Korea.

METHODS

Patients (n=101) with IDEM or epidural metastatic spinal tumors at the cord level underwent surgeries monitored with SSEP and/or MEP. The monitoring rate was defined as negative when MEP or SSEP could not be measured after reversal of the neuromuscular block under general anesthesia. Positive IOM changes included more than a 50% change in the MEP or SSEP amplitude and more than a 10% delay in SSEP latency.

RESULTS

MEP was measurable in 73% of patients. The MEP monitoring rate in patients with motor power grades of 3 or less was 39%, which was lower than that of SSEP (83%). The sensitivity, specificity and predictability of MEP for motor changes were 93, 90 and 91%, respectively. Conversely, the sensitivity, specificity and predictability of SSEP were 62, 97 and 89%, respectively. In patients in whom MEP was not measurable (n=24), SSEP was monitored with a predictability of 83%.

CONCLUSION

In cases of extramedullary spinal tumors, MEP shows a higher sensitivity than SSEP does. However, the monitoring rate of MEP in non-ambulatory patients was lower than that of SSEP. In those cases, SSEP can be useful to monitor for postoperative neurological deficits.

Family-based Whole Exome Sequencing of Autism Spectrum Disorder Reveals Novel De Novo Variants in Korean Population

Objectives

The objective of this family-based whole exome sequencing (WES) is to examine genetic variants of autism spectrum disorder (ASD) in Korean population.

Methods

The probands with ASD and their biological parents were recruited in this study. We ascertained diagnosis based on DSM-5™ criteria, using Autism Diagnostic Observation Schedule and Autism Diagnostic Interview–Revised. We selected probands with typical phenotypes of ASD both in social interaction/communication and repetitive behaviour/limited interest domains, with intellectual disability (IQ < 70), for attaining homogeneity of the phenotypes. First, we performed WES minimum 50× for 13 probands and high-coverage pooled sequencing for their parents. We performed additional WES for 38 trio families, at least 100× depth. De novo mutations were confirmed by Sanger sequencing. All the sequence reads were mapped onto the human reference genome (hg19 without Y chromosome). Bioinformatics analyses were performed by BWA-MEM, Picard, GATK, and snpEff for variant annotation. We selected de novo mutation candidates from probands, which are neither detected in two pooled samples nor both parents.

Results

Fifty-one subjects with ASD (5 females, 40∼175 months, mean IQ 42) and their families were included in this study. We discovered 109 de novo variants from 46 families. Twenty-nine variants are expected to be amino acid changing, potentially causing deleterious effects. We assume CELSR3, MYH1, ATXN1, IDUA, NFKB1, and C4A/C4B may have adverse effect on central nerve system.

Conclusions

We observed novel de novo variants which are assumed to contribute to development of ASD with typical phenotypes and low intelligence in WES study.

Disclosure of interest

This work has been supported by Healthcare Technology R&D project (No: A120029) by Ministry of Health and Welfare, Republic of Korea.

RGD Conjugated Dendritic Polylysine for Cellular Delivery of Antisense Oligonucleotide

Dendritic polylysines (DPL) are highly branched nano-sized spherical polymer with positively charged primary amino groups on surface. This structural feature is useful for a delivery of antisense oligonucleotide or siRNA. In this study, we modified the surface of DPL with cyclic RGD (and iRGD) peptide by conjugation reaction generating RGD (and iRGD) peptide conjugated dendritic poly-lysines, RGD-DPL or iRGD-DPL. The prepared conjugates were evaluated for integrin receptor-mediated cellular delivery of antisense oligonucleotide. The conjugation of RGD or iRGD peptide on DPL was monitored by measuring the retention time in capillary zone electrophoresis and the absorbance at UV-Vis spectroscopy. Cellular delivery by DPL-RGD (or -iRGD)/antisense oligonucleotide complex was examined by antisense splicing correction assay on integrin alpha v/beta 3 positive A375B3-Luc cells, which were stably transfected with plasmid pLuc/705. DPL-RGD (or -iRGD)/antisense oligonucleotide complexes exhibited integrin receptor mediated uptake on A375B3 cells without inducing cellular toxicity. In addition, the delivery of antisense oligonucleotide was integrin receptor-dependent with moderate efficiency.

Preparation of Pluronic Grafted Dendritic alpha,epsilon-poly(L-lysine)s and Characterization as a Delivery Adjuvant of Antisense Oligonucleotide

A series of pluronic grafted dendritic alpha,epsilon-poly(L-lysine)s (DPL-PF127) were synthesized by a conjugation reaction and evaluated the potential use of DPL-PF127 as a delivery agent of antisense oligonucleotide into A375 B3 cells. The structural features of the DPL-PF127 were identified by NMR and FT-IR. The number of pluronic F127 on DPL surface, determined by fluorescamine assay, increased proportionally to the mole ratio between DPL and activated PF127 in reaction. DPL- PF127 showed the physical properties of decrease in zetapotential and increase in size as the mole ratio of PF127 to DPL increased. The complex formation of DPL-PF127 with oligonucleotide was confirmed by running capillary zone electrophoresis (CZE) and agarose gel electrophoresis. DPL-PF127, prepared at the mole ratio of 1:10 in reaction, was the most suitable as a delivery adjuvant of oligonucleotide. In addition, DPL-PF127/oligonucleotide complexes were taken into A375B3 cell without cellular toxicity and delivered antisense oligonucleotide into cell.

Five-year decreased incidence of surgical site infections following gastrectomy and prosthetic joint replacement surgery through active surveillance by the Korean Nosocomial Infection Surveillance System

BACKGROUND

Surveillance of healthcare-associated infection has been associated with a reduction in surgical site infection (SSI).

AIM

To evaluate the Korean Nosocomial Infection Surveillance System (KONIS) in order to assess its effects on SSI since it was introduced.

METHODS

SSI data after gastrectomy, total hip arthroplasty (THA), and total knee arthroplasty (TKA) between 2008 and 2012 were analysed. The pooled incidence of SSI was calculated for each year; the same analyses were also conducted from hospitals that had participated in KONIS for at least three consecutive years. Standardized SSI rates for each year were calculated by adjusting for SSI risk factors. SSI trends were analysed using the Cochran-Armitage test.

FINDINGS

The SSI rate following gastrectomy was 3.12% (522/16,918). There was a significant trend of decreased crude SSI rates over five years. This trend was also evident in analysis of hospitals that had participated for more than three years. The SSI rate for THA was 2.05% (157/7656), which decreased significantly from 2008 to 2012. The risk factors for SSI after THA included the National Nosocomial Infections Surveillance risk index, trauma, reoperation, and age (60-69 years). The SSI rate for TKA was 1.90% (152/7648), which also decreased significantly during a period of five years. However, the risk-adjusted analysis of SSI did not show a significant decrease for all surgical procedures.

CONCLUSION

The SSI incidence of gastrectomy and prosthetic joint replacement declined over five years as a result of active surveillance by KONIS.

Trends in the distribution and antimicrobial susceptibility of causative pathogens of device-associated infection in Korean intensive care units from 2006 to 2013: results from the Korean Nosocomial Infections Surveillance System (KONIS)

BACKGROUND

For all countries, information on pathogens causing healthcare-associated infections is important in order to develop proper strategies for preventing and treating nosocomial infections.

AIM

To assess the change in frequencies and antimicrobial resistance of pathogens causing device-associated infections (DAIs) in intensive care units (ICUs) in South Korea between July 2006 and June 2014.

METHODS

Data from the Korean Nosocomial Infections Surveillance System (KONIS) were analysed, including three major DAI types in ICUs.

FINDINGS

The frequency of Gram-negative bacteria gradually increased for central line-associated bloodstream infection (CLABSI) and ventilator-associated pneumonia (VAP) (from 24.6% to 32.6% and from 52.8% to 73.5%, respectively). By contrast, the frequency of Gram-positive bacteria decreased from 58.6% to 49.2% for CLABSI, and from 44.3% to 23.8% for VAP (P < 0.001). Staphylococcus aureus was the most frequent causative pathogen in CLABSI throughout the surveillance period, but for VAP was replaced as the most frequent pathogen by Acinetobacter baumannii as of 2010. Candida albicans was the most frequent pathogen for catheter-associated urinary tract infection. The meticillin resistance rate in S. aureus decreased from 95% to 90.2% (P < 0.001); amikacin resistance in Klebsiella pneumoniae and Escherichia coli decreased from 43.8% to 14.7% and from 15.0% to 1.8%, respectively (P < 0.001); imipenem resistance in A. baumannii increased from 52.9% to 89.8% (P < 0.001).

CONCLUSION

The proportion of Gram-negative bacteria as nosocomial pathogens for CLABSI and VAP has increased. The prevalence of A. baumannii causing DAIs in Korean ICUs has increased rapidly, as has the rate of carbapenem resistance in these bacteria.

Trends in the incidence rate of device-associated infections in intensive care units after the establishment of the Korean Nosocomial Infections Surveillance System

BACKGROUND

The effectiveness of continuous nationwide surveillance on healthcare-associated infections should be investigated in each country.

AIM

To assess the rate of device-associated infections (DAIs) in intensive care units (ICUs) since the establishment of the Korean Nosocomial Infections Surveillance System (KONIS).

METHODS

Nationwide data were obtained on the incidence rate of DAI in ICUs reported to KONIS by all participating hospitals. The three major DAIs were studied: ventilator-associated pneumonia (VAP), central line-associated bloodstream infection (CABSI), and catheter-associated urinary tract infection (CAUTI). The pooled and year-wise incidence rates (cases per 1000 device-days) of these DAIs were determined for the period 2006 and 2012. In addition, data from institutions that had participated in KONIS for at least three consecutive years were analysed separately.

FINDINGS

The number of ICUs participating in KONIS gradually increased from 76 in 2006 to 162 in 2012. Between 2006 and 2012, the incidence rate per 1000 device-days for VAP decreased significantly from 3.48 to 1.64 (F = 11, P < 0.01), for CAUTI the rate decreased non-significantly from 1.85 to 1.26 (F = 2.02, P = 0.07), and for CABSI the rate also decreased non-significantly from 3.4 to 2.57 (F = 1.73, P = 0.12). In the 132 ICUs that had participated in KONIS for at least three consecutive years, the VAP rate significantly decreased from the first year to third year (F = 20.57, P < 0.01), but the rates of CAUTI (F = 1.06, P = 0.35) and CABSI (F = 1.39, P = 0.25) did not change significantly.

CONCLUSION

The decreased incidence rate of VAP in ICUs in Korea might be associated with the continuous prospective surveillance provided by KONIS.

The prevalence of bronchiectasis in patients with Marfan syndrome

An association has been suggested between Marfan syndrome (MFS) and the nodular bronchiectatic form of lung disease caused by non-tuberculous mycobacteria (NTM). We evaluated the prevalence of bronchiectasis in 79 adult patients with MFS using computed tomography (CT) imaging. Airway dilation indicative of bronchiectasis (22/79, 28%) and bronchioloectasis (10/79, 13%) were relatively common, although the extent of dilation was not severe and was frequently confined to a single lobe. However, bronchiolitis was evident in only three patients (4%), and no patient was diagnosed with NTM lung disease.

Factors related with metastasis of right retroesophageal lymph nodes in papillary thyroid cancer

AIM

Right retroesophageal lymph nodes (RRLNs) should be involved in central lymph nodes (CLNs) dissection in patients with papillary thyroid cancer (PTC). This study assessed the incidence and factors related to RRLNs metastasis.

METHODS

From January 2008 to March 2010, 129 patients who underwent total thyroidectomy with CLNs dissection including RRLNs were enrolled. The predictive value of RRLNs metastasis was assessed.

RESULTS

Twenty six (20.1%) of 129 patients exhibited nodal metastasis in RRLNs. Metastasis of RRLNs was associated with large tumor size (>1 cm; P<0.01), multiplicity (P=0.03), preoperative LN enlargement (P<0.01), metastasis of non-retroesophageal lateral LN (P<0.01) and large number of CLNs metastases (P<0.01) in univariate analysis. Multivariate analysis revealed that tumor size (>1 cm) and metastasis of non-retroesophageal lateral LN were independent correlates of RRLNs metastases.

CONCLUSION

RRLNs may be removed during operation for PTC, particularly in patients with tumor >1 cm and lateral LN metastases.

Evolution of atomic structure in Al75Cu25 liquid from experimental and ab initio molecular dynamics simulation studies

X-ray diffraction and electrostatic levitation measurements, together with the ab initio molecular dynamics simulation of liquid Al(75)Cu(25) alloy have been performed from 800 to 1600 K. Experimental and ab initio molecular dynamics simulation results match well with each other. No abnormal changes were experimentally detected in the specific heat capacity over total hemispheric emissivity and density curves in the studied temperature range for a bulk liquid Al(75)Cu(25) alloy measured by the electrostatic levitation technique. The structure factors gained by the ab initio molecular dynamics simulation precisely coincide with the experimental data. The atomic structure analyzed by the Honeycutt-Andersen index and Voronoi tessellation methods shows that icosahedral-like atomic clusters prevail in the liquid Al(75)Cu(25) alloy and the atomic clusters evolve continuously. All results obtained here suggest that no liquid-liquid transition appears in the bulk liquid Al(75)Cu(25) alloy in the studied temperature range.

Andrographolide inhibits HMGB1-induced inflammatory responses in human umbilical vein endothelial cells and in murine polymicrobial sepsis

AIM

Nuclear DNA-binding protein high-mobility group box 1 (HMGB1) protein acts as a late mediator of severe vascular inflammatory conditions, such as septic shock, upregulating pro-inflammatory cytokines. Andrographolide (AG) is isolated from the plant of Andrographis paniculata and used as a folk medicine for treatment of viral infection, diarrhoea, dysentery and fever. However, the effect of AG on HMGB1-induced inflammatory response has not been studied.

METHODS

Firstly, we accessed this question by monitoring the effects of post-treatment AG on lipopolysaccharide (LPS) and caecal ligation and puncture (CLP)-mediated release of HMGB1 and HMGB1-mediated regulation of pro-inflammatory responses in human umbilical vein endothelial cells (HUVECs) and septic mice.

RESULTS

Post-treatment AG was found to suppress LPS-mediated release of HMGB1 and HMGB1-mediated cytoskeletal rearrangements. AG also inhibited HMGB1-mediated hyperpermeability and leucocyte migration in septic mice. In addition, AG inhibited production of tumour necrosis factor-α (TNF-α) and activation of AKT, nuclear factor-κB (NF-κB) and extracellular-regulated kinases (ERK) 1/2 by HMGB1 in HUVECs. AG also induced downregulation of CLP-induced release of HMGB1, production of interleukin (IL) 1β/6/8 and mortality.

CONCLUSION

Collectively, these results suggest that AG may be regarded as a candidate therapeutic agent for the treatment of vascular inflammatory diseases via inhibition of the HMGB1 signalling pathway.

The novel miR-9500 regulates the proliferation and migration of human lung cancer cells by targeting Akt1

MicroRNAs have crucial roles in lung cancer cell development. They regulate cell growth, proliferation and migration by mediating the expression of tumor suppressor genes and oncogenes. We identified and characterized the novel miR-9500 in human lung cancer cells. The miR-9500 forms a stem-loop structure and is conserved in other mammals. The expression levels of miR-9500 were reduced in lung cancer cells and lung cancer tissues compared with normal tissues, as verified by TaqMan miRNA assays. It was confirmed that the putative target gene, Akt1, was directly suppressed by miR-9500, as demonstrated by a luciferase reporter assay. The miR-9500 significantly repressed the protein expression levels of Akt1, as demonstrated via western blot, but did not affect the corresponding mRNA levels. Akt1 has an important role in lung carcinogenesis, and depletion of Akt1 has been shown to have antiproliferative and anti-migratory effects in previous studies. In the current study, the overexpression of miR-9500 inhibited cell proliferation and the expression of cell cycle-related proteins. Likewise, the overexpression of miR-9500 impeded cell migration in human lung cancer cells. In an in vivo assay, miR-9500 significantly suppressed Fluc expression compared with NC and ASO-miR-9500, suggesting that cell proliferation was inhibited in nude mice. Likewise, miR-9500 repressed tumorigenesis and metastasis by targeting Akt1. These data indicate that miR-9500 might be applicable for lung cancer therapy.