bluuebunny/crossref_metadata_2025 huggingface dataset:
Age-dependent regulation of SARS-CoV-2 cell entry genes and cell death programs correlates with COVID-19 disease severity
Authors: Inde Zintis , Yapp Clarence , Joshi Gaurav N. , Spetz Johan , Fraser Cameron , Deskin Brian , Ghelfi Elisa , Sodhi Chhinder , Hackam David J. , Kobzik Lester , Croker Ben A. , Brownfield Douglas , Jia Hongpeng , Sarosiek Kristopher A.
Published: September 2020

Angiotensin-converting enzyme 2 (ACE2) maintains cardiovascular and renal homeostasis but also serves as the entry receptor for the novel severe acute respiratory syndrome coronavirus (SARS-CoV-2), the causal agent of novel coronavirus disease 2019 (COVID-19)1. COVID-19 disease severity, while highly variable, is typically lower in pediatric patients than adults (particularly the elderly), but increased rates of hospitalizations requiring intensive care are observed in infants than in older children. The reasons for these differences are unknown. To detect potential age-based correlates of disease severity, we measured ACE2 protein expression at the single cell level in human lung tissue specimens from over 100 donors from ∼4 months to 75 years of age. We found that expression of ACE2 in distal lung epithelial cells generally increases with advancing age but exhibits extreme intra- and inter-individual heterogeneity. Notably, we also detected ACE2 expression on neonatal airway epithelial cells and within the lung parenchyma. Similar patterns were found at the transcript level:ACE2mRNA is expressed in the lung and trachea shortly after birth, downregulated during childhood, and again expressed at high levels in late adulthood in alveolar epithelial cells. Furthermore, we find that apoptosis, which is a natural host defense system against viral infection, is also dynamically regulated during lung maturation, resulting in periods of heightened apoptotic priming and dependence on pro-survival BCL-2 family proteins including MCL-1. Infection of human lung cells with SARS-CoV-2 triggers an unfolded protein stress response and upregulation of the endogenous MCL-1 inhibitor Noxa; in juveniles, MCL-1 inhibition is sufficient to trigger apoptosis in lung epithelial cells – this may limit virion production and inflammatory signaling. Overall, we identify strong and distinct correlates of COVID-19 disease severity across lifespan and advance our understanding of the regulation of ACE2 and cell death programs in the mammalian lung. Furthermore, our work provides the framework for potential translation of apoptosis modulating drugs as novel treatments for COVID-19.
Subject identification using edge-centric functional connectivity
Authors: Jo Youngheun , Faskowitz Joshua , Esfahlani Farnaz Zamani , Sporns Olaf , Betzel Richard F.
Published: September 2020

Group-level studies do not capture individual differences in network organization, an important prerequisite for understanding neural substrates shaping behavior and for developing interventions in clinical conditions. Recent studies have employed “fingerprinting” analyses on functional connectivity to identify subjects’ idiosyncratic features. Here, we develop a complementary approach based on an edge-centric model of functional connectivity, which focuses on the co-fluctuations of edges. We first show whole-brain edge functional connectivity (eFC) to be a robust substrate that improves identifiability over nodal FC (nFC) across different datasets and parcellations. Next, we characterized subjects’ identifiability at different spatial scales, from single nodes to the level of functional systems and clusters using k-means clustering. Across spatial scales, we find that heteromodal brain regions exhibit consistently greater identifiability than unimodal, sensorimotor, and limbic regions. Lastly, we show that identifiability can be further improved by reconstructing eFC using specific subsets of its principal components. In summary, our results highlight the utility of the edge-centric network model for capturing meaningful subject-specific features and sets the stage for future investigations into individual differences using edge-centric models.
Stable colony stimulating factor 1 fusion protein treatment increases HSC pool and enhances their mobilisation in mice
Authors: Kaur Simranpreet , Sehgal Anuj , Wu Andy C. , Millard Susan M , Batoon Lena , Ferrari-Cestari Michelle , Levesque Jean-Pierre , Hume David A. , Raggatt Liza J. , Pettit Allison R.
Published: September 2020

Prior chemotherapy and/or underlying morbidity commonly leads to poor mobilisation of hematopoietic stem cells (HSC) for transplantation in cancer patients. Increasing the number of available HSC prior to mobilisation is a potential strategy to overcome this deficiency. Resident bone marrow (BM) macrophages are essential for maintenance of niches that support HSC and enable engraftment in transplant recipients. Here we examined potential of donor treatment with colony stimulating factor-1 (CSF1) to modify the BM niche and expand the potential HSC pool for autologous transplantation. We administrated CSF1 Fc fusion protein (CSF1-Fc) to naive C57Bl/6 mice and assessed the impacts on HSC number and function and overall haematopoiesis. Outcomes were assessed byin situimaging andex vivoflow cytometry with functional validation by colony formation and competitive transplantation assay. CSF1-Fc treatment caused a transient expansion of monocyte-macrophage cells within BM and spleen at the expense of BM B lymphopoiesis and hematopoietic stem and progenitor cell (HSPC) homeostasis. During the recovery phase after cessation of CSF1-Fc treatment, normalisation of haematopoiesis was accompanied by an increase in the total available HSPC pool. In the spleen, increased HSC was associated with expression of the BM niche marker CD169 in red pulp macrophages. Pre-treatment with CSF1-Fc increased the number and reconstitution potential of HSPC in blood following a HSC mobilising regimen of granulocyte colony stimulating factor (G-CSF) treatment. These results indicate that CSF1-Fc conditioning could represent a therapeutic strategy to overcome poor HSC mobilisation and subsequently improve autologous or heterologous HSC transplantation outcomes.

Key points

1) Recovery from Fc-modified colony stimulating factor-1 (CSF1-Fc) treatment was accompanied by an increase in total haematopoietic stem cells. 2) Pre-conditioning with CSF1-Fc increased the reconstitution potential of blood after haematopoietic stem cell mobilisation.
Enzymatic synthesis of fatty acid amides using microbial lipids as acyl group-donors and their biological activities
Authors: El-Baz Hatim A. , Elazzazy Ahmed M. , Saleh Tamer S. , Dritsas Panagiotis , Mahyoub Jazem A. , Baeshen Mohammed N. , Madian Hekmat R. , Alkhaled Mohammed , Aggelis George
Published: September 2020

Fatty acid amides (FAAs) are of great interest due to their broad industrial applications. They can be synthesized enzymatically with many advantages over chemical synthesis. In this study, the fatty acid moieties of lipids ofCunninghamella echinulataATHUM 4411,Umbelopsis isabellinaATHUM 2935,Nannochloropsis gaditanaCCAP 849/5, Olive oil and an eicosapentaenoic acid (EPA) concentrate were converted into their fatty acid methyl esters and used in the FAA (i.e. ethylene diamine amides) enzymatic synthesis, using lipases as biocatalysts. The FAA synthesis, monitored usingin situNMR, FT-IR and thin-layer chromatography, was catalyzed efficiently by the immobilizedCandida rugosalipase. The synthesized FAAs exhibited a significant antimicrobial activity, especially those containing oleic acid in high proportions (i.e. derived from Olive oil andU. isabellinaoil), against several human pathogenic microorganisms, insecticidal activity against yellow fever mosquito, especially those ofC. echinulatacontaining gamma linolenic acid, and anti-cancer properties against SKOV-3 ovarian cancer cell line, especially those containing EPA in their structures (i.e. EPA concentrate andN. gaditanaoil). We conclude that FAAs can be efficiently synthesized using microbial oils of different fatty acid composition and used in specific biological applications.
Endothelial-to-hematopoietic transition is induced by Notch glycosylation and upregulation of Mycn
Authors: Laruy Briane , Garcia-Gonzalez Irene , Casquero-Garcia Veronica , Benedito Rui
Published: September 2020

A better understanding of the molecular mechanisms driving hematopoietic stem cell (HSC) specification and expansion may enable better pharmacological strategies to produce them in sufficient numbers for transplantation. In the embryo, HSCs arise from a defined subset of arterial endothelial cells (ECs) located in the aorta–gonad–mesonephros (AGM) region that undergo endothelial-to-hematopoietic transition (EHT). Arterialization and HSC development are generally believed to require the action of Notch. Here we show that although Notch activity is initially required for arterialization, it is detrimental to subsequent EHT. Mechanistically, we show that effective EHT depends on a Mfng-induced decrease in Jag1-Notch signaling in hemogenic ECs. This causes upregulation of Mycn, an important metabolic and cell-cycle regulator that we found to be required for EHT. During the subsequent development of hematopoietic lineages,Mycnexpression decreases and its function is taken on by the homologousMycgene.
Patient-Derived Mutant Forms of NFE2L2/NRF2 Drive Aggressive Murine Hepatoblastomas
Authors: Wang Huabo , Lu Jie , Mandel Jordan A. , Zhang Weiqi , Schwalbe Marie , Gorka Joanna , Liu Ying , Marburger Brady , Wang Jinglin , Ranganathan Sarangarajan , Prochownik Edward V.
Published: September 2020

Background and Aims

Hepatoblastoma (HB), the most common pediatric liver cancer, often bears β-catenin mutations and deregulates the Hippo tumor suppressor pathway. Murine HBs can be generated by co-expressing β-catenin mutants and the constitutively active Hippo effector YAPS127A. Some HBs and other cancers also express mutants of NFE2L2/NRF2 (NFE2L2), a transcription factor that tempers oxidative and electrophilic stress. In doing so, NFE2L2 either suppresses or facilitates tumorigenesis.

Methods

We evaluated NFE2L2’s role in HB pathogenesis by co-expressing all combinations of mutant β-catenin, YAPS127Aand the patient-derived NFE2L2 mutants L30P and R34P in murine livers. We evaluated growth, biochemical and metabolic profiles and transcriptomes of the ensuing tumors.

Results

In association with β-catenin+YAPS127A, L30P and R34P markedly accelerated HB growth and generated widespread cyst formation and necrosis, which are otherwise uncommon features. Surprisingly, any two members of the mutant β-catenin-YAPS127A-L30P/R34P triad were tumorigenic, thus directly establishing NFE2L2’s oncogenicity. Each tumor group displayed distinct features but shared 22 similarly deregulated transcripts, 10 of which perfectly correlated with survival in human HBs and 17 of which correlated with survival in multiple adult cancers. One highly up-regulated transcript encoded serpin E1, a serine protease inhibitor that regulates fibrinolysis, growth and extracellular matrix. The combination of mutant β-catenin, YAPS127Aand Serpin E1, while not accelerating cystogenic tumor growth, did promote the wide-spread necrosis associated with mutant β-catenin-YAPS127A-L30P/R34P tumors.

Conclusions

Our findings establish the direct oncogenicity of NFE2L2 mutants and key transcripts, including serpin E1, that drive specific HB features.
Single-molecule spectroscopy reveals dynamic allostery mediated by the substrate-binding domain of a AAA+ machine
Authors: Iljina Marija , Mazal Hisham , Goloubinoff Pierre , Riven Inbal , Haran Gilad
Published: September 2020

ClpB is an ATP-dependent protein disaggregation machine that is activated on demand by co-chaperones and by aggregates caused by heat shock or mutations. The regulation of ClpB’s function is critical, since its persistent activation is toxicin vivo. Each ClpB molecule is composed of an auxiliary N-terminal domain (NTD), an essential regulatory middle domain (MD) that activates the machine by tilting, and two nucleotide-binding domains that are responsible for ATP-fuelled substrate threading. The NTD is generally thought to serve as a substrate-binding domain, which is commonly considered to be dispensable for ClpB’s activity, and is not well-characterized structurally due to its high mobility. Here we use single-molecule FRET spectroscopy to directly monitor the real-time dynamics of ClpB’s NTD and reveal its involvement in novel allosteric interactions. We find that the NTD fluctuates on a microsecond timescale and, unexpectedly, shows little change in conformational dynamics upon binding of a substrate protein. During its fast motion, the NTD makes crucial contacts with the regulatory MD, directly affecting its conformational state and thereby influencing the overall ATPase and unfolding activity of this machine. Moreover, we also show that the NTD mediates signal transduction to the nucleotide-binding domains through conserved residues. The two regulatory pathways revealed here enable the NTD to suppress the MD in the absence of protein substrate, and to limit ATPase and disaggregation activities of ClpB. The use of multiple parallel allosteric pathways involving ultrafast domain motions might be common to AAA+ molecular machines to ensure their fast and reversible activation.
Application of subject-specific adaptive mechanical loading for bone healing in a mouse tail vertebral defect
Authors: Malhotra Angad , Walle Matthias , Paul Graeme R. , Kuhn Gisela A. , Müller Ralph
Published: September 2020

Methods to repair bone defects arising from trauma, resection, or disease, continue to be sought after. Cyclic mechanical loading is well established to influence bone (re)modelling activity, in which bone formation and resorption are correlated to micro-scale strain. Based on this, the application of mechanical stimulation across a bone defect could improve healing. However, if ignoring the mechanical integrity of defected bone, loading regimes have a high potential to either cause damage or be ineffective. This study explores real-time finite element (rtFE) methods that use three-dimensional structural analyses from micro-computed tomography images to estimate effective peak cyclic loads in a subject-specific and time-dependent manner. It demonstrates the concept in a cyclically loaded mouse caudal vertebral bone defect model. Using rtFE analysis combined with adaptive mechanical loading, mouse bone healing was significantly improved over non-loaded controls, with no incidence of vertebral fractures. Such rtFE-driven adaptive loading regimes demonstrated here could be relevant to clinical bone defect healing scenarios, where mechanical loading can become patient-specific and more efficacious. This is achieved by accounting for initial bone defect conditions and spatio-temporal healing, both being factors that are always unique to the patient.
Differential expression of transposable elements in stem cell lineages of the preimplantation embryo
Authors: Dai Eddie , Alvarez Nehemiah S. , Rumi M. A. Karim
Published: September 2020

Approximately half of the human genome is comprised of transposable elements (TEs), which are genetic elements capable of amplifying themselves within the genome. Throughout the course of human life, TEs are expressed in germ cells, the preimplantation embryo, and the placenta but silenced elsewhere. However, the functions of TEs during embryonic development are poorly understood. Trophoblast stem (TS), embryonic stem (ES), and extraembryonic endoderm stem (XEN) cells are cell lineages derived from the preimplantation embryo and known to have different TE silencing mechanisms. Thus, it is likely distinct TEs are expressed in each lineage and that proteins coded by these TEs have lineage-specific functions. The purpose of this research was to determine which TEs are expressed in each of these stem cell lineages and to compare expression levels between lineages. Each lineage’s transcriptome was analyzed by quantifying TE expression in RNA-sequencing data from mouse stem cells. Expression data were then used for differential expression analyses performed between the cell types. It was found that certain families of TEs are distinctly expressed in certain lineages, suggesting expression of these families may be involved in the differentiation and development of each lineage, the understanding of which can lead to improved stem cell therapies and capacity to study human embryonic development.
scGCN: a Graph Convolutional Networks Algorithm for Knowledge Transfer in Single Cell Omics
Authors: Song Qianqian , Su Jing , Zhang Wei
Published: September 2020

Single-cell omics represent the fastest-growing genomics data type in the literature and the public genomics repositories. Leveraging the growing repository of labeled datasets and transferring labels from existing datasets to newly generated datasets will empower the exploration of the single-cell omics. The current label transfer methods have limited performance, largely due to the intrinsic heterogeneity and extrinsic differences between datasets. Here, we present a robust graph-based artificial intelligence model, single-cell Graph Convolutional Network (scGCN), to achieve effective knowledge transfer across disparate datasets. Benchmarked with other label transfer methods on totally 30 single cell omics datasets, scGCN has consistently demonstrated superior accuracy on leveraging cells from different tissues, platforms, and species, as well as cells profiled at different molecular layers. scGCN is implemented as an integrated workflow as a python software, which is available athttps://github.com/QSong-github/scGCN.
Sustained neural activity correlates with rapid perceptual learning of auditory patterns
Authors: Herrmann Björn , Araz Kurdo , Johnsrude Ingrid S.
Published: September 2020

Repeating structures forming regular patterns are common in sounds. Learning such patterns may enable accurate perceptual organization. In five experiments, we investigated the behavioral and neural signatures of rapid perceptual learning of regular sound patterns. We show that recurring (compared to novel) patterns are detected more quickly and increase sensitivity to pattern deviations and to the temporal order of pattern onset relative to a visual stimulus. Sustained neural activity reflected perceptual learning in two ways. Firstly, sustained activity increased earlier for recurring than novel patterns when participants attended to sounds, but not when they ignored them; this earlier increase mirrored the rapid perceptual learning we observed behaviorally. Secondly, the magnitude of sustained activity was generally lower for recurring than novel patterns, but only for trials later in the experiment, and independent of whether participants attended to or ignored sounds. The late manifestation of sustained activity reduction suggests that it is not directly related to rapid perceptual learning, but to a mechanism that does not require attention to sound. In sum, we demonstrate that the latency of sustained activity reflects rapid perceptual learning of auditory patterns, while the magnitude may reflect a result of learning, such as better prediction of learned auditory patterns.
Suppression of amyloid-β secretion from neurons bycis-9,trans-11-octadecadienoic acid, an isomer of conjugated linoleic acid
Authors: Hata Saori , Kikuchi Kazunori , Kano Kuniyuki , Saito Haruka , Sobu Yuriko , Kinoshita Shoichi , Saito Takashi , Saido Takaomi C. , Sano Yoshitake , Taru Hidenori , Aoki Junken , Komano Hiroto , Tomita Taisuke , Natori Shunji , Suzuki Toshiharu
Published: September 2020

Conjugated linoleic acid (CLA) comprises several geometric and positional isomers of the parental linoleic acid (LA). Two of the isomers, cis-9, trans-11 CLA (c9,t11 CLA) and trans-10, cis-12 CLA (t10,c12 CLA) exert various biological activities. However, the effect of CLA on generation of neurotoxic amyloid-β (Aβ) protein remains unclear. We found that c9,t11CLA significantly suppressed generation of Aβ in primary cultures of mouse neurons. CLA treatment did not affect the levels of β-site APP-cleaving enzyme 1 (BACE1), a component of active γ-secretase complex presenilin 1 amino-terminal fragment (PS1 NTF), or Aβ protein precursor (APP) in cultured neurons. BACE1 activity in lysate of neurons treated with c9,t11 CLA, but not t10,c12 CLA, decreased slightly, although c9,t11 CLA did not directly affect the activity of recombinant BACE1. Interestingly, localization of BACE1 and APP in early endosomes increased in neurons treated with c9,t11 CLA; concomitantly, the localization of both proteins was reduced in late endosomes, where APP is predominantly cleaved by BACE1. c9,t11 CLA and t10,c12 CLA appeared to be incorporated into membrane phospholipids, as the level of CLA-containing lysophosphatidylcholine (CLA-LPC) increased dramatically in neurons incubated with CLA. Taken together, our findings indicate that accumulation of c9,t11 CLA-LPC, but not t10,c12 CLA-LPC, in neuronal membranes suppresses amyloidogenic cleavage of APP, thereby contributing to preservation of brain neurons by suppressing neurotoxic Aβ production in aged subjects.
Brain Endothelial Cell TRPA1 Channels Initiate Neurovascular Coupling
Authors: Thakore Pratish , Alvarado Michael G. , Ali Sher , Mughal Amreen , Pires Paulo W. , Yamasaki Evan , Pritchard Harry A. T. , Isakson Brant E. , Tran Cam Ha T. , Earley Scott
Published: September 2020

Blood flow regulation in the brain is dynamically regulated to meet the metabolic demands of active neuronal populations. Recent evidence has demonstrated that capillary endothelial cells are essential mediators of neurovascular coupling that sense neuronal activity and generate a retrograde, propagating, hyperpolarizing signal that dilates upstream arterioles. Here, we tested the hypothesis that transient receptor potential ankyrin 1 (TRPA1) channels in capillary endothelial cells are significant contributors to functional hyperemic responses that underlie neurovascular coupling in the brain. Using an integrativeex vivoandin vivoapproach, we demonstrate the functional presence of TRPA1 channels in brain capillary endothelial cells, and show that activation of these channels within the capillary bed, including the post-arteriole transitional region covered by ensheathing mural cells, initiates a retrograde signal that dilates upstream parenchymal arterioles. Notably, this signaling exhibits a unique biphasic mode of propagation that begins within the capillary network as a short-range, Ca2+signal dependent on endothelial pannexin-1 channel/purinergic P2X receptor communication pathway and then is converted to a rapid, inward-rectifying K+channel-mediated electrical signal in the post-arteriole transitional region that propagates upstream to parenchymal arterioles. Two-photon laser-scanning microscopy further demonstrated that conductive vasodilation occursin vivo, and that TRPA1 is necessary for functional hyperemia within the somatosensory cortex of mice. Together, these data establish a role for endothelial TRPA1 channels as sensors of neuronal activity and show that they respond accordingly by initiating a vasodilatory response that redirects blood to regions of metabolic demand.
Syringeal vocal folds do not have a voice in zebra finch vocal development
Authors: Maxwell Alyssa , Adam Iris , Larsen Pernille S. , Sørensen Peter G. , Elemans Coen P.H.
Published: September 2020

Vocal behaviour can be dramatically changed by both neural circuit development and postnatal maturation of the body. During song learning in songbirds, both the song system and syringeal muscles are functionally changing, but it is unknown if maturation of sound generators within the syrinx contributes to vocal development. Here we densely sample the respiratory pressure control space of the zebra finch syrinxin vitro. We show that the syrinx produces sound very efficiently and that key acoustic parameters, minimal fundamental frequency, entropy and source level, do not change over development in both sexes. Thus, our data suggests that the observed acoustic changes in vocal development must be attributed to changes in the motor control pathway, from song system circuitry to muscle force, and not by material property changes in the avian analog of the vocal folds. We propose that in songbirds, muscle use and training driven by the sexually dimorphic song system are the crucial drivers that lead to sexual dimorphism of the syringeal skeleton and musculature. The size and properties of the instrument are thus not changing, while its player is.
The role of work authenticity in linking strengths use to career satisfaction and proactive behavior: a two-wave study
Authors: Matsuo Makoto
Published: September 2020

Purpose

Although positive psychology asserts that authenticity comes from identifying and using our strengths, no quantitative research has been conducted to test that relationship. This study aims to examine the mediating role of work authenticity in linking strengths use to career satisfaction and proactive behavior.

Design/methodology/approach

Using a two-wave survey with nurses in two large, acute hospitals in Japan (n = 298), a structural equation model was produced.

Findings

The results show that work authenticity fully mediated between strengths use and career satisfaction, and that work authenticity partially mediated between strengths use and proactive behavior.

Research limitations/implications

As work authenticity, career satisfaction and proactive behavior were measured at time 2, it is desirable to conduct a three-wave survey to measure these variables separately in future research.

Practical implications

It may be imperative to recognize that employees who use their strengths are satisfied with their careers only by enhancing authenticity at work.

Originality/value

The main contribution of this study was to identify the mediating role of work authenticity in linking strengths use to both career-related well-being and proactive work behaviors.
Construct validity of public service motivation in India: a comparison of two measures
Authors: Gupta Rajneesh , Dash Sanket , Kakkar Shiva , Yadav Ramashankar
Published: September 2020

Purpose

Public service motivation (PSM) is a universal construct, but indigenous traditions and culture of a country are known to influence its measurement. Currently, no research on PSM in India is available. To facilitate PSM research in India, this article compares the two most used measures of PSM (PSM-14 and PSM-16) to identify the most suitable scale for further exploration.

Design/methodology/approach

The study uses a cross-sectional survey research design. Data were collected from 387 employees working in the public sector. ADANCO, a PLS-SEM package, was used to analyze the data.

Findings

Contrary to expectations, it was found that the older PSM-14 exhibited better psychometric properties than the newer PSM-16. The PSM-14 also exhibited greater predictive validity than PSM-16.

Practical implications

The study demonstrates that PSM is a valid construct in India and can be measured adequately by existing instruments. However, certain sub-dimensions of the scale (such as compassion) may be reworded/changed to reflect Indian cultural ethos better.

Originality/value

The findings will be tremendously helpful to researchers interested in examining the correlates of PSM in the Indian context by making it easier to select the appropriate measurement instrument. The study also provides a careful examination of each of the sub-dimensions of the construct to enable the development of more robust PSM measures in the future.
Sport attendance behavior spectrum: motivators, constraints and context
Authors: Mayer Kurt C. , Hungenberg Eric
Published: September 2020

Purpose

The purpose of this paper was to explore a new sport attendance behavior spectrum framework where sport consumer behavior is not derived from just a dichotomy of a motivator positively impacting attendance or a constraint negatively impacting attendance. Rather, when accounting for the context of the setting (e.g. sport, playing level, locality, patron type, etc.), some areas belong on a spectrum that fluctuates between positive and negative impacts on attendance that are dependent on the context of the given environment.

Design/methodology/approach

Through factor analysis and structural equation modeling, the proposed model attempted to explain relationships between five second-order factors and game attendance, which expanded to include the new internal contextual and external contextual factors, and ultimately team fandom.

Findings

The results indicated three significant main effects where internal contextual exhibited a positive relationship with attendance, while constraints and external contextual demonstrated a negative relationship. Internal and external motives were not significant. Further, the moderating effect of high and low sport interest groupings largely indicated no significant spectator differences. The model explained 24% of the variance in attendance, and attendance accounted for 41% of the variance in team fandom.

Originality/value

Attendance is intricate, and this study highlighted the importance of considering and adapting to the sporting context as some factors exist on a sport attendance behavior spectrum and differently impact spectators positively or negatively, given the context of the setting. Further, in this lower-level sport setting, consumers viewed minor league hockey more as a leisure commodity than a premier sport contest.
Three-way interaction effect of social media usage, perceived task interdependence and perceived participative leadership on employee creativity
Authors: Chen Lifan , Zheng Bowen , Liu Hefu , Deng Manting
Published: September 2020

Purpose

Despite the growing use of social media in many organizations, managers face the challenges of how to effectively manage social media usage (SMU) in the workplace to ensure employee creativity. This study combined task-technology fit theory and the interactional perspective of employee creativity to understand the three-way interaction of SMU, perceived task interdependence, and perceived participative leadership on employee creativity.

Design/methodology/approach

A questionnaire survey was designed to test our hypotheses. The sample consisted of employees who use social media in the workplace. A total of 402 valid questionnaires were used for the hierarchical regression analysis.

Findings

SMU had the strongest positive relationship with creativity when perceived task interdependence and perceived participative leadership were high. However, we did not find two-way interaction effects of SMU and perceived task interdependence on employee creativity.

Originality/value

Our findings are aligned with the emergent view that the benefits of SMU can be better realized when it coexists with a set of complementary team contextual factors. The current study helps extend the contingency perspective and related studies in social media literature and employee creativity research.
Korean Treasury Bond Futures Pricing Model
Authors: Choi Youngsoo , Jin O Se , Seo Jae Yeong
Published: September 2020

This paper proposes two alternative methods which are used for pricing the theoretical value of the KTB futures on the non-traded underlying asset; first method is to use the CKLS model, under which the volatility of interest rate changes is highly sensitive to the level of the interest rate, and then employ binomial trees to compute the theoretical value of futures, second one is to use the multifactor Vasicek model considering correlations between yields-to-maturity and then employ the Monte Carlo simulation to compute it. In the empirical study on KTB303 and KTB306, an CKLS methodology is superior to the conventional KORFX method based on the cost-of-carry model in terms of the size of difference between market price and theoretical price. However, the phenomena, the price discrepancy using the KOFEX methodology is very small for all test perlod, implies that the KOFEX one is being used for the most market participants. The reasons that an multifactor Vasicek methodlogy is performed poorly in comparison to another methods are 1) the Vasicek model might be not a good model for explaining the level of interest rates, or 2) the important point considered by the most market participants may be on the volatility or interest rate, not on the correlations between yields-to-maturity.
Convexity Analysis of Option Embedded Bonds
Authors: Hyeon O Seung
Published: September 2020

Interest rate risk hedge strategies usually assume that term structure of interest rates in moving under a specific way. If a real term structure is moving differently from the assumed term structure movement, the interest rate risk hedge strategies assuming the special term structure movement may incur unexpected large loss for a bond portfolio manager. Hence an interest rate risk hedge strategy which could be effective under various types of term structure movements has been strongly needed by bond portfolio managers. Duration vector strategies have been developed to satisfy this practical need. To allow various types of term structure movements, duration vector strategies assume multi-factor models for the term structure movement. When a duration vector strategy is considered as a generalization of a duration strategy which is a single factor model for the term structure movement, there will be a generalized concept which measures convexity of a bond under the duration vector model. This study identifies the convexity property of an option embedded bond portfolio under ‘key rate duration model‘ which is a kind of duration vector model suggested by Ho (1992).
The Effect of Futures Trading on Spot Market Liquidity
Authors: Ohk Ki Yool
Published: September 2020

This study analyzes the effect of stock index futures trading on the price volatility and liquidity of spot markets, It is found that spot price volatility increases significantly after stock index futures are listed, This study partitions the trading activity series of sPOt markets into expected and unexpected components, and documents that unexpected spot-trading activities are associated with smaller sPOt price movements subsequent to the introduction of futures trading, This imolies that spot market liquidity has been increased by the intraduction of futures trading, Furthermore, this study examines the effect of futures-trading activity on the liquidity of spot markets, Results show that active futures markets enhance the liquidity of soot markets.
An Examination of International Portfolio Diversification Benefits for Korean Investors
Authors: Min Byoung-Kyu , Kim Tong Suk
Published: September 2020

We employ mean‐variance spanning and intersection tests in the stochastic discount factor approach to examine the potential diversification benefits of international investments from the perspective of Korean investors. Our results show that the addition of international regional indices to the set of domestic equities provides significant diversification benefits. However, the source and economic magnitude of diversification benefits differ across international markets. Furthermore, we find that when investors manage their portfolio based on instrument variables, they can not only expand their investment opportunities by investing in international assets, but also increase the efficiency gain of diversification benefits.
Volatility and Trading Volumes of Trader Types in KOSPI200 Index, Futures, and Options Markets
Authors: Yoo Shiyong
Published: September 2020

In this study, we explore the empirical relationship between trading volume and volatility among KOSPI200 index stock market, futures and options markets. In particular, in explaining the volatility of each market, the trading in other markets, as well as the trading volume of other markets, also served as explanatory variables. In other words, cross-market effects of trading volume by investor types are analyzed. The empirical results show that there exist the cross-market effects of the relationship between trading volume and volatility in deeply integrated financial markets such as KOSPI200 index stock, futures and options markets. That is, the volatility of one market is explained by the trading volume of trader types in other financial markets. And, overall options trading increases the volatility of each market, while the overall futures trading volume of foreign investors reduce the volatility of each market. Trading volume of Individual investors does not reduce the volatilities of KOSPI200 index and futures markets. That is, trading volume of Individual investors in stock, futures, and options markets increase the volatilities of stock and futures. This implies that foreign investors are informed traders, whereas individual investors are liquidity traders.
Hedging Price Risk in the Presence of Quantity Risk
Authors: Kim In Joon , Lee Dong Haeng
Published: September 2020

This research looks into hedge strategies to resolve foreign exchange-related risks, generated when investing in overseas financial assets, as an example of quantity risk. If an investor has information with no uncertainty over the volume and there is only a price risk he want to hedge, an investor will be able to reduce or eliminate risks by using relative derivative securities such as forwards or futures contracts. However, if there are uncertainties over the volume of hedging targets that is called quantity risk, it is impossible to set the optimal hedge ratio with the traditional method without considering the presence of quantity risk. In this paper, we theoretically draw an optimal hedge ratio which is estimated via minimal variance criterion under static hedge structure. We also analyze its hedge performance and the impact of change in covariance on the optimal hedge ratio and variance of investment return denominated as its own country currency. For theoretical approach, we review the impact that overseas financial assets’ yield and exchanges rates distribution will have on optimal hedge ratio through simple numerical analysis. Empirical analysis is carried out by using the stock indices of the U.S., Europe and Asian countries, and the results indicate that hedge strategies taken with quantity risk for all markets produced better hedging performance than the strategies taken without quantity risk. Since there is a need for systematic research on risks involving foreign exchanges that occur in the event of foreign investments aimed to develop the domestic financial industry, we hope that our research serve as a stepping-stone for further research.
The Effect of Operation and Market Value Efficiency on the Korean Stock Market
Authors: Kim Soo-Hyun
Published: September 2020

This paper investigates the relationship between output to input efficiency and stock return predictability in the Korean stock market. We measure the efficiency using Data Envelopment Analysis with independent outputs of sales and market value data. Sales efficiency measures the operational efficiency whereas market value efficiency measures the efficiency evaluated by the investors. Through our empirical analysis, it is found that low efficiency stocks in either measures tend to have higher future returns. However, if both efficiency measures are employed at the same time there exists a strong tendency that high operation efficient and low market value efficient stocks generate larger future returns. We find that DEA analysis for efficiency can process a cross-sectional stock return predictability in the Korean stock market.
Do Frequent Tradings Add Value? Profitability of Equity Fund Investors
Authors: Paek Miyoun , Ko Kwangsoo
Published: September 2020

This study examines the effects of fund managers’ frequent tradings on equity mutual funds. Based on the findings, we suggest policy implications for mutual fund regulations. The empirical findings are as follows. First, frequent tradings cause poor performance of equity funds regardless of trading costs. Second, managers of underperforming funds buy and sell their portfolio holdings more frequently than those of outperforming funds. This implies that high trading cost is not the only source of the fund’s poor performance that exhibit frequent tradings. This phenomenon seems to be closely related to an agency problem between fund managers and investors. Finally, even when we control for the effects of fund size and cash flows, frequent tradings generate poorer performance, too. Noteworthy is that the negative impact of frequent tradings on fund return is strong for funds with heavy outflows. Our findings suggest that regulators need to strengthen the monitoring system of fund management.
Corporate Payout Policy and CEO‘s Inside Debt Holdings
Authors: Kim Yura , Yun Jeongsun , Choi Hyun Woo , Hwang Gyuyoung
Published: September 2020

Literature documents that executives' inside debt holdings (debt-based managerial compensation) such as defined-benefit pensions and retirement funds are often unfunded and unsecured and have long maturities, and thus provide managerial incentives to pursue strategies to avoid the overall firm risk. This study investigates the effect of managerial inside debt compensation relative to equity-based compensation on a firm's dividend payout policy. We find that a inside debt holdings are positively associated with various measures of a firm's dividend payout policy. Additionally, we find empirical evidence in firms with inside debt holdings that the inverse relationship between high default risk measured by KZ index and dividend payout weakens as the portion of inside debt relative to equity-based compensation rises. This finding indicates that the needs for the firm to restrain dividend payouts to equity holders is reduced as the executive's debt-to-equity compensation ratio becomes larger. Overall, the results suggests the mitigating effect of executives' inside debt holdings on the conflicts between bondholders and shareholders can lead to generous payout policy.
Estimating the Risk-Return Relation in the Korean Stock Market
Authors: Park Dojoon , Eom Young Ho , Hahn Jaehoon
Published: September 2020

Finance theory such as Merton’s ICAPM suggests that there should be a positive relationship between the expected return and risk. Empirical evidence on this relationship, however, is far from conclusive. Building on the recent econometric research on this topic such as Lundblad (2007) and Hedegaard and Hodrick (2016), we estimate the risk-return relation implied in the ICAPM using a long sample (1962~2016) of daily, weekly, and monthly excess stock returns in Korea. More specifically, we estimate various volatility models including GARCH-M using the overlapping data inference (ODIN) method suggested by Hedegaard and Hodrick (2016), as well as the traditional maximum likelihood estimation methodology. For the full sample period, we fail to find a positive risk-return relationship that is significant and robust. For the subsample period from 1998 to 2016, however, we find a significantly positive risk-return relation for GARCH-M model regardless of return intervals and estimation methods. This result is also robust to using other specifications such as EGARCH-M which includes the leverage effect of the variance process and EGARCH-M-GED whose conditional distribution has fatter tails. Our findings suggest that there is indeed a positive relationship between the expected return and risk in the Korean stock market, at least for the period after 1998.
An Empirical Study on Moral Hazard of Life Insurance : Evidence from Postal Insurance Market
Authors: Lee Iljoo , Lee Changjun
Published: September 2020

Due to the difficulty in obtaining data on life insurance contracts, previous studies on moral hazard of life insurance are confined to conceptual discussion or surveys of Korean health panel. To fill this gap, using comprehensive data from Postal insurance market, we perform an empirical study on moral hazard of life insurance from the period of 2008 to 2013. Our empirical findings are summarized as follows. First, employing the Heckman (1979)'s two stage model, we find that having indemnity private health insurance increases the number and period of medical utilization. In addition, number of private health insurance has a positive and highly significant effect on the number of period of medical utilization. Our empirical finding indicates that in a life insurance market with asymmetric information, there exists a moral hazard in order to maximize economic utility.
Volatility of Corporate Debt Financing and Cross-Section of Stock Returns : Empirical Analysis of Financial Constraint Puzzle in Korea
Authors: Kim Heonsoo , Chong Byung-Uk , Hwang In-Deok
Published: September 2020

This paper investigates the effects of the volatility of debt financing on cross-sectional variation of stock returns. Through the empirical analysis of listed firms in Korea for the 2005-2016 estimation period, this paper provides persistent and significant evidence that the volatility of debt financing has negative impacts on stock returns while controlling for market factor and firm characteristics such as size factor (firm size, market capitalization), value factor (book-to-market ratio), and momentum factor. While using both monthly average of stock returns and Fama-French-Carhart 4-factor risk-adjusted stock returns as dependent variables, the estimations of Fama-MacBeth cross-sectional regressions produce negative and statistically significant coefficient on the volatility of debt financing. The findings of this paper makes an academic contribution by providing the evidence that the volatility of debt financing, as a measure of financial constraint, plays a role as an anomaly factor for “financial constraint pricing puzzle” in Korean stock market.
The Effect of Equity Linked Securities on Financial Stability in Korea
Authors: Yoon Sun-Joong , Jung Jaehoon
Published: September 2020

Since the introduction of ELS (Equity-linked securities) in 2003, the structured products have become one of the most important investment vehicles to Korean retail investors. However, the rapid growth of those structured products has induced the imbalance of Korean financial markets and may have eventually damaged the financial stability of Korean economy. In this paper, we investigate how Korean securities companies issuing the structured products hedge their positions and how their activities affect the financial stability. In addition, we conduct a simple empirical analysis to examine the relationship between the issue of ELS and the financial stability using FSI (financial stability index) provided by Bank of Korea. According to the results, the balance of ELS affects the financial stability negatively and this is significant even after adjusting for the control variables such as the KOSPI index, VKOSPI, the risk-free interest rate, and CPI. More specifically, the balance rather than the amount of monthly issuance is significant to financial stability. In addition, the decrease in underlying indices reduces the early redemption, thereby damaging the financial stability. Lastly, we suggest several solutions to alleviate the negative effects.