Nosocomial transmission of COVID-19 among immunocompromised hosts can have a serious impact on COVID-19 severity, underlying disease progression and SARS-CoV-2 transmission to other patients and healthcare workers within hospitals. We experienced a nosocomial outbreak of COVID-19 in the setting of a daycare unit for paediatric and young adult cancer patients. Between 9 and 18 November 2020, 473 individuals (181 patients, 247 caregivers/siblings and 45 staff members) were exposed to the index case, who was a nursing staff. Among them, three patients and four caregivers were infected. Two 5-year-old cancer patients with COVID-19 were not severely ill, but a 25-year-old cancer patient showed prolonged shedding of SARS-CoV-2 RNA for at least 12 weeks, which probably infected his mother at home approximately 7–8 weeks after the initial diagnosis. Except for this case, no secondary transmission was observed from the confirmed cases in either the hospital or the community. To conclude, in the day care setting of immunocompromised children and young adults, the rate of in-hospital transmission of SARS-CoV-2 was 1.6% when applying the stringent policy of infection prevention and control, including universal mask application and rapid and extensive contact investigation. Severely immunocompromised children/young adults with COVID-19 would have to be carefully managed after the mandatory isolation period while keeping the possibility of prolonged shedding of live virus in mind.

Echinochloa species are among the most troublesome weeds in rice cultivation, and grow in a broad habitat range in Korea. Although various ecotypes of Echinochloa have been collected as germplasm for future studies, it has been difficult to classify them due to their high level of morphological similarity. This study was thus conducted to develop and investigate the phylogenetic relationships between 77 Echinochloa accessions with the use of 23 simple sequence repeat (SSR) markers and 24 morphological traits. Of 77 Echinochloa accessions, including 57 accessions from Korea and 5 reference species, late watergrass was clearly clustered as a distinctive group from barnyardgrass and other Echinochloa species. In this analysis, we also identified core genetic and morphological markers that can be used for the future identification and classification of Echinochloa species. Five out of 23 SSR makers produced distinctive bands that discriminate late watergrass from barnyardgrass and other Echinochloa species. Four morphological traits of the reproductive organs were the most influential contributors for classifying Echinochloa species. Although there was no clear consensus generated in this study between SSR markers and morphological trait analyses, our results support the potential use of the selected SSR markers and morphological traits in future studies of Echinochloa.

Liposomal drug delivery products have been already commercialized in tumor therapeutics, which can realize passive tumor targeting via enhanced permeability and retention (EPR) effect resulting from the leaky tumor vasculature. To control drug release out of the liposomes, thermo-sensitive liposomes (TSLs) have been developed so that an abrupt exposure of highly concentrated drugs to tumor tissues was enabled by locally treated thermal stimuli. As interests upon TSL have increased along with ongoing clinical trials, some types of TSLs with different physical properties in pharmacokinetics and the mechanism of drug release have been formulated. However, there are few protocols established with a desirable heat source to maximize the efficacy of different TSLs as treating tumors. In this study, we examined different protocols for the most effective application of different TSLs to tumor therapy. First, we examined if enhancing the accumulation of TSLs within tumor tissues prior to bursting drugs out of TSLs could lead to increasing anti-tumor efficacy. Second, we compared the efficiency of two different heat sources on the use of TSL, a warm water bath (42°C) and high intensity focused ultrasound (HIFU). Our study suggests that the specified protocol be setup for TSLs with different physical properties to optimally function in tumor therapies.

The growth of high-quality indium (In)-rich InXGa1−XN alloys is technologically important for applications to attain highly efficient green light-emitting diodes and solar cells. However, phase separation and composition modulation in In-rich InXGa1−XN alloys are inevitable phenomena that degrade the crystal quality of In-rich InXGa1−XN layers. Composition modulations were observed in the In-rich InXGa1−XN layers with various In compositions. The In composition modulation in the InXGa1−XN alloys formed in samples with In compositions exceeding 47%. The misfit strain between the InGaN layer and the GaN buffer retarded the composition modulation, which resulted in the formation of modulated regions 100 nm above the In0.67Ga0.33N/GaN interface. The composition modulations were formed on the specific crystallographic planes of both the {0001} and {0114} planes of InGaN.

Leaf stomatal characteristics of Siberian elm (Ulmus pumila) were investigated by electron microscopy and white light scanning interferometry. On the basis of average annual precipitations, two types of tree specimens were collected from Korea, China, and Mongolia: (1) trees under normal environmental conditions and (2) trees under arid conditions. Field emission scanning electron microscopy revealed oval-shaped stomata on the lower surface, and they were ca. 20 μm in width. In-lens secondary electron imaging showed differences in electron density and stomatal pore depth between the two types. According to the line profile analysis by white light scanning interferometry, stomata under arid conditions appeared to have higher levels of the stomatal pore depth than ones under normal conditions. Focused ion beam–field emission electron microscopy supported the increased stomatal pore depth with the increasing drought stress gradient. These results suggest that complementary microscopy can be employed to unravel the adaptive phenotypic plasticity of Siberian elm in response to drought stress.

Sources of variation in nutrient intake have been examined for Western diets, but little is known about the sources of variation and their differences by age and sex among Koreans. We examined sources of variation in nutrient intake and calculated the number of days needed to estimate usual intake using 12 d of dietary records (DR). To this end, four 3 d DR including two weekdays and one weekend day were collected throughout four seasons of 1 year from 178 male and 236 female adults aged 20–65 years residing in Seoul, Korea. The sources of variation were estimated using the random-effects model, and the variation ratio (within-individual:between-individual) was calculated to determine a desirable number of days. Variations attributable to the day of the week, recording sequence and seasonality were generally small, although the degree of variation differed by sex and age (20–45 years and 46–65 years). The correlation coefficient between the true intake and the observed intake (r) increased with additional DR days, reaching 0·7 at 3–4 d and 0·8 at 6–7 d. However, the degree of increase became attenuated with additional days: r increased by 13·0–26·9 % from 2 to 4 d, by 6·5–16·4 % from 4 to 7 d and by 4·0–11·6 % from 7 to 12 d for energy and fifteen nutrients. In conclusion, the present study suggests that the day of the week, recording sequence and seasonality minimally contribute to the variation in nutrient intake. To measure Korean usual dietary intake using open-ended dietary instruments, 3–4 d may be needed to achieve modest precision (r>0·7) and 6–7 d for high precision (r>0·8).

We previously demonstrated that the chronic consumption of a high-fat diet (HFD) promotes lung and liver metastases of 4T1 mammary carcinoma cells in obesity-resistant BALB/c mice. To examine early transcriptional responses to tumour progression in the liver and lungs of HFD-fed mice, 4-week-old female BALB/c mice were divided into four groups: sham-injected, control diet (CD)-fed; sham-injected, HFD-fed (SH); 4T1 cell-injected, CD-fed (TC); 4T1 cell-injected, HFD-fed (TH). Following 16 weeks of either a CD or HFD, 4T1 cells were injected into the mammary fat pads of mice in the TC and TH groups and all mice were continuously fed identical diets. At 14 d post-injection, RNA was isolated from hepatic and pulmonary tissues for microarray analysis of mRNA expression. Functional annotation and core network analyses were conducted for the TH/SH Unique gene set. Inflammation in hepatic tissues and cell mitosis in pulmonary tissues were the most significant biological functions in the TH/SH Unique gene set. The biological core networks of the hepatic TH/SH Unique gene set were characterised as those genes involved in the activation of acute inflammatory responses (Orm1, Lbp, Hp and Cfb), disordered lipid metabolism and deregulated cell cycle progression. Networks of the pulmonary Unique gene set displayed the deregulation of cell cycle progression (Cdc20, Cdk1 and Bub1b). These HFD-influenced alterations may have led to favourable conditions for the formation of both pro-inflammatory and pro-mitotic microenvironments in the target organs that promote immune cell infiltration and differentiation, as well as the infiltration and proliferation of metastatic tumour cells.

Background: Highly educated participants with normal cognition show lower incidence of Alzheimer's disease (AD) than poorly educated participants, whereas longitudinal studies involving AD have reported that higher education is associated with more rapid cognitive decline. We aimed to evaluate whether highly educated amnestic mild cognitive impairment (aMCI) participants show more rapid cognitive decline than those with lower levels of education.

Methods: A total of 249 aMCI patients enrolled from 31 memory clinics using the standard assessment and diagnostic processes were followed with neuropsychological evaluation (duration 17.2 ± 8.8 months). According to baseline performances on memory tests, participants were divided into early-stage aMCI (−1.5 to −1.0 standard deviation (SD)) and late-stage aMCI (below −1.5 SD) groups. Risk of AD conversion and changes in neuropsychological performances according to the level of education were evaluated.

Results: Sixty-two patients converted to AD over a mean follow-up of 1.43 years. The risk of AD conversion was higher in late-stage aMCI than early-stage aMCI. Cox proportional hazard models showed that aMCI participants, and late-stage aMCI participants in particular, with higher levels of education had a higher risk of AD conversion than those with lower levels of education. Late-stage aMCI participants with higher education showed faster cognitive decline in language, memory, and Clinical Dementia Rating Sum of Boxes (CDR-SOB) scores. On the contrary, early-stage aMCI participants with higher education showed slower cognitive decline in MMSE and CDR-SOB scores.

Conclusions: Our findings suggest that the protective effects of education against cognitive decline remain in early-stage aMCI and disappear in late-stage aMCI.

The incidence and severity of Clostridium difficile infections (CDI) have increased in Western countries. However, there are limited data regarding the epidemiology of CDI in Eastern countries. This nationwide study was conducted in 17 hospitals to determine temporal trends in CDI incidence (from 2004 to 2008) in South Korea. The total incidence of CDI in Korea was 1·7 cases/1000 adult admissions in 2004, and 2·7/1000 cases in 2008 (P = 0·028). When analysing the clinical features of 1367 CDI patients diagnosed in 2008, oral metronidazole was effective as a first-line treatment for CDI (61·9%). Relapse rate was 8·9% and complicated CDI was only observed in 3·6%. The incidence of CDI increased significantly in Korea from 2004 to 2008. Although the clinical features were milder than in Western countries, the increasing burden of CDI needs ongoing surveillance systems.

We have investigated the nonthermal bioplasma sources and their characteristics as well as their interactions with biological cells. The electron temperature and plasma density are measured to be about 1.5 eV and 3×1012 cm-3 , respectively, for the direct palsma jet under Ar gas flow. The hydroxyl radical density has also been investigated and measured to be maximum value of about 3 ×1015 cm-3 and 8 ×1014 cm-3 in the direct plasma jet and dielectric barrier discharge bioplasma, respectively, by the ultraviolet optical absorption spectroscopy. Herein, we have investigated the basic interactions of these nonthermal bioplasma with the living organisms in morphological and biomolecular aspects. We found that the secondary electron emision coefficient of the biological surface has been drastically increased by atmospheric bioplasma, which indicates the biological surface to be oxidized especially by the hydroxyl (OH) radical species. In order to elucidate the basic mechanisms for the cell shrinking and apoptosis leading to a cell death by the nonthermal bioplasma, the cell membrane potential has been estimated based on the ROS density as well as cell capacitances. It is also found that the molecular electron energy band structure in the biological cells have been shifted closer toward the vacuum surface and accordingly their central energy of molecular band becomes small by the nonthermal bioplasma due to cell oxidation caused by OH radicals.

We present a rapid and sensitive surface acoustic wave (SAW) immunosensor that utilizes gold staining as a signal enhancement method. A sandwich immunoassay was performed on sensing area of the SAW sensor, which could specifically capture and detect cardiac markers (cardiac troponin I (cTnI), creatine kinase (CK)-MB, and myoglobin). The analytes in human serum were captured on gold nanoparticles (AuNPs) that were conjugated in advance with detection antibodies. Introduction of these complexes to the capture antibody-immobilized sensor surface resulted in a classic AuNP-based sandwich immunoassay format that has been used for signal amplification. In order to achieve further signal enhancement, a gold staining method was performed, which demonstrated that it is possible to obtain gold staining-mediated signal augmentation on a mass-sensitive device. The sensor response due to gold staining varied as a function of cardiac marker concentration.

Somatic cell nuclear transfer (SCNT) has emerged as an important tool for producing transgenic animals and deriving transgenic embryonic stem cells. The process of SCNT involves fusion of in vitro matured oocytes with somatic cells to make embryos that are transgenic when the nuclear donor somatic cells carry ‘foreign’ DNA and are clones when all the donor cells are genetically identical. However, in canines, it is difficult to obtain enough mature oocytes for successful SCNT due to the very low efficiency of in vitro oocyte maturation in this species that hinders canine transgenic cloning. One solution is to use oocytes from a different species or even a different genus, such as bovine oocytes, that can be matured easily in vitro. Accordingly, the aim of this study was: (1) to establish a canine fetal fibroblast line transfected with the green fluorescent protein (GFP) gene; and (2) to investigate in vitro embryonic development of canine cloned embryos derived from transgenic and non-transgenic cell lines using bovine in vitro matured oocytes. Canine fetal fibroblasts were transfected with constructs containing the GFP and puromycin resistance genes using FuGENE 6®. Viability levels of these cells were determined by the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay. Interspecies SCNT (iSCNT) embryos from normal or transfected cells were produced and cultured in vitro. The MTT measurement of GFP-transfected fetal fibroblasts (mean OD = 0.25) was not significantly different from non-transfected fetal fibroblasts (mean OD = 0.35). There was no difference between transgenic iSCNT versus non-transgenic iSCNT embryos in terms of fusion rates (73.1% and 75.7%, respectively), cleavage rates (69.7% vs. 73.8%) and development to the 8–16-cell stage (40.1% vs. 42.7%). Embryos derived from the transfected cells completely expressed GFP at the 2-cell, 4-cell, and 8–16-cell stages without mosaicism. In summary, our results demonstrated that, following successful isolation of canine transgenic cells, iSCNT embryos developed to early pre-implantation stages in vitro, showing stable GFP expression. These canine–bovine iSCNT embryos can be used for further in vitro analysis of canine transgenic cells and will contribute to the production of various transgenic dogs for use as specific human disease models.

High-resolution imaging and quantitative surface analysis of epicuticular waxes and epistomatal chambers of pine species were performed by field emission scanning electron microscopy and white light scanning interferometry. Both juvenile and adult needles were collected from the two-year-old seedlings of Pinus rigida and Pinus densiflora and subjected to surface observations. Epicuticular wax structures developed on the cuticle layer as well as in the epistomatal chambers and appeared to occlude the cavities in the two pine species. The stomata of P. densiflora were characterized by more distinctly raised rings around openings than P. rigida. The most common epicuticular wax structures of the two pine species included tubules with terminal openings and coiled rodlets. Wax platelets were deposited on epistomatal chambers. Either rodlets or tubules seemed to be longer and thicker in P. rigida than those in P. densiflora. White light scanning interferometry revealed quantitative surface profiles, demonstrating more ridged (ca. 4 μm high) stomatal apertures and nearly twofold deeper (ca. 20 μm deep) epistomatal chambers of P. densiflora than those of P. rigida. These results suggest that white light scanning interferometry can be applied to unravel the quantitative surface features of epicuticular sculptures on plant leaves.