31 results on '"Paik SM"'
Search Results
2. Association between grit and insomnia: A population-based study.
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Kim JR, Park JA, Kim HJ, Yoon JE, Oh D, Park HJ, Paik SM, Lee WJ, Kim D, Yang KI, Chu MK, and Yun CH
- Abstract
Background: This study aimed to investigate the association of the grit scale, a personality trait characterized by perseverance and passion, with both the presence and the severity of insomnia in the Korean adult population., Methods: A nationwide population-based cross-sectional survey was conducted through face-to-face interviews using structured questionnaires between September and December 2018 in Korea. Grit was assessed by using the 8-item Short Grit Scale. Participants were categorized into insomnia and non-insomnia groups based on a threshold of 10 on the Insomnia Severity Index (ISI). The association between girt and insomnia was analyzed using multiple linear regression and multivariable logistic regression, controlling for sociodemographic factors, lifestyles, and comorbidities., Results: A total of 2453 participants (49.9 % male; aged 19-92 years) were enrolled in the study. Individual grit scores ranged from 1.75 to 5.00 points (mean [SD], 3.27 [0.42]), and insomnia was present in 16.5 % of the population. The insomnia group exhibited lower grit score compared to the non-insomnia group (3.11 [0.40] vs. 3.30 [0.42], p < 0.001, Cohen's d = 0.46). Grit was negatively associated with ISI scores (β = -0.15, 95 % CI = -0.19, -0.11, p < 0.001) and with having insomnia (OR 0.40, 95 % CI = 0.30, 0.55, p < 0.001), after controlling for covariates., Conclusions: Individuals with higher grit were less likely to have insomnia. Clinicians should consider personality traits, such as grit, in the evaluation and the management of insomnia., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)
- Published
- 2024
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3. Predicting motor gains with home-based telerehabilitation after stroke.
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Paik SM and Cramer SC
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- Female, Humans, Ambulatory Care Facilities, Movement, Recovery of Function, Treatment Outcome, Male, Stroke therapy, Stroke Rehabilitation methods, Telerehabilitation methods
- Abstract
Introduction: Telerehabilitation (TR) may be useful for rehabilitation therapy after stroke. However, stroke is a heterogeneous condition, and not all patients can be expected to derive the same benefit from TR, underscoring the need to identify predictors of response to TR., Methods: A prior trial provided patients with 6 weeks of intensive rehabilitation therapy targeting arm movement, randomly assigned to be provided in the home via TR (current focus) or in clinic. Eligible patients had moderate arm motor deficits and were in the subacute-chronic stage post stroke. Behavioral gains were measured as change in the arm motor Fugl-Meyer score from baseline to 30 days post therapy. To delineate predictors of TR response, multivariable linear regression was performed, advancing the most significant predictor from each of eight categories: patient demographics, stroke characteristics, medical history, rehabilitation therapy outside of study procedures, motivation, sensorimotor impairment, cognitive/affective deficits, and functional status., Results: The primary focus was on patients starting TR >90 days post stroke onset ( n = 44), among whom female sex, less spasticity, and less visual field defects predicted greater motor gains. This model explained 39.3% of the variance in treatment-related gains. In secondary analysis that also included TR patients enrolled ≤90 days post stroke (total n = 59), only female sex was a predictor of treatment gains. A separate secondary analysis examined patients >90 days post stroke ( n = 34) randomized to in-clinic therapy, among whom starting therapy earlier post stroke and less ataxia predicted greater motor gains., Discussion: Response to TR varies across patients, emphasizing the need to identify characteristics that predict treatment-related behavioral gain. The current study highlights factors that might be important to patient selection for home-based TR after stroke., Competing Interests: Declaration of conflicting interestsThe authors declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Dr. Cramer serves as a consultant for Abbvie, Constant Therapeutics, MicroTransponder, Neurolutions, SanBio, Fujifilm Toyama Chemical Co., NeuExcell, Elevian, Medtronic, and TRCare.
- Published
- 2023
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4. Coordinated Health Care Interventions for Childhood Asthma Gaps in Outcomes (CHICAGO) plan.
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Krishnan JA, Margellos-Anast H, Kumar R, Africk JJ, Berbaum M, Bracken N, Chen YF, DeLisa J, Erwin K, Ignoffo S, Illendula SD, Kim H, Lohff C, MacTavish T, Martin MA, Mosnaim GS, Nguyen H, Norell S, Nyenhuis SM, Paik SM, Pittsenbarger Z, Press VG, Sculley J, Thompson TM, Zun L, Gerald LB, and McDermott M
- Abstract
Background: Evidence-based strategies to improve outcomes in minority children with uncontrolled asthma discharged from the emergency department (ED) are needed., Objectives: This multicenter pragmatic clinical trial was designed to compare an ED-only intervention (decision support tool), an ED-only intervention and home visits by community health workers for 6 months (ED-plus-home), and enhanced usual care (UC)., Methods: Children aged 5 to 11 years with uncontrolled asthma were enrolled. The change over 6 months in the Patient-Reported Outcomes Measurement Information System Asthma Impact Scale score in children and Satisfaction with Participation in Social Roles score in caregivers were the primary outcomes. The secondary outcomes included guideline-recommended ED discharge care and self-management., Results: Recruitment was significantly lower than expected (373 vs 640 expected). Of the 373 children (64% Black and 31% Latino children), only 63% completed the 6-month follow-up visit. In multivariable analyses that accounted for missing data, the adjusted odds ratios and 98% CIs for differences in Asthma Impact Scores or caregivers' Satisfaction with Participation in Social Roles scores were not significant. However, guideline-recommended ED discharge care was significantly improved in the intervention groups versus in the UC group, and self-management behaviors were significantly improved in the ED-plus-home group versus in the ED-only and UC groups., Conclusions: The ED-based interventions did not significantly improve the primary clinical outcomes, although the study was likely underpowered. Although guideline-recommended ED discharge care and self-management did improve, their effect on clinical outcomes needs further study., Competing Interests: In the past 12 months, J. Krishnan has received research funding from the National Institutes of Health/National Heart, Lung and Blood Institute (NIH/NHLBI), the American Lung Association, and the Patient-Centered Outcomes Institute, as well as consulting fees from GlaxoSmithKline, the American Thoracic Society, and BData Inc. G. Mosnaim currently receives research grant support from GlaxoSmithKline, Novartis, Sanofi-Regneron, and Teva, and in the past 12 months she has received research grant support from Astra-Zeneca, Alk-Abelló and Genentech. In the past 12 months, L. Gerald has received research funding from the NIH/NHLBI, the American Lung Association, the US Centers for Disease Control and Prevention, the Robert Wood Johnson Foundation, the Patient-Centered Outcomes Institute, and the Southwest Environmental Health Sciences Center, as well as consulting fees from Up-to-Date. V. Press reports receiving funding from the National Institutes of Health (grant R01HL146644) and the Agency for Health Care Research and Quality (grant R01HS027804) as well as consultant fees from Vizient, Inc, and Humana. S. M. Nyenhuis receives funding from the National Institutes of Health, royalties from Wolters/Kluwer and Springer, and consultant fees from PRIME Education. The rest of the authors declare that they have no relevant conflicts of interest.
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- 2023
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5. Overproduction of recombinant E. coli malate synthase enhances Chlamydomonas reinhardtii biomass by upregulating heterotrophic metabolism.
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Paik SM, Kim J, Jin E, and Jeon NL
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- Biomass, Glyoxylates metabolism, Heterotrophic Processes, Isocitrate Lyase metabolism, Malates metabolism, Photosynthesis, Up-Regulation, Chlamydomonas reinhardtii metabolism, Escherichia coli enzymology, Malate Synthase metabolism
- Abstract
High uptake of malate and efficient distribution of intracellular malate to organelles contributed to biomass increase, reducing maintenance energy. In this study, transgenic Chlamydomonas reinhardtii was developed that stably expresses malate synthase in the chloroplast. The strains under glyoxylate treatment showed 19% more increase in microalgal biomass than wild-type. By RNA analysis, transcript levels of malate dehydrogenase (MDH4) and acetyl-CoA synthetase (ACS3), isocitrate lyase (ICL1) and malate synthase (MAS1), were significantly more expressed (17%, 42%, 24%, and 18% respectively), which was consistent with reported heterotrophic metabolism flux analysis with the objective function maximizing biomass. Photosynthetic F
v /Fm was slightly reduced. A more meticulous analysis is necessary, but, in the transgenic microalgae with malate synthase overexpression, the metabolism is likely to more rely on heterotrophic energy production via TCA cycle and glyoxylate shunt than on photosynthesis, resulting in the increase in microalgal biomass., (Copyright © 2018 Elsevier Ltd. All rights reserved.)- Published
- 2019
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6. Microstructure guided multi-scale liquid patterning on an open surface.
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Park D, Kang M, Choi JW, Paik SM, Ko J, Lee S, Lee Y, Son K, Ha J, Choi M, Park W, Kim HY, and Jeon NL
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- Equipment Design, Human Umbilical Vein Endothelial Cells cytology, Humans, Surface Properties, Tissue Array Analysis instrumentation, Tissue Array Analysis methods
- Abstract
Liquid patterning is a quintessential aspect in cell-based screening. While there are a variety of methods to handle microliquids utilizing surface treatments, complex microfluidic systems, and automated dispensing, most of the stated methods are both expensive and difficult to implement. Here, we present a fast multi-scale microliquid-patterning method on an open surface using embossed microstructures without surface modification. Arrays of micropillars can trap microliquids when a bulk drop is swept by an elastic sweeper on polystyrene (PS) substrates. The patterning mechanism on a basic form of a 2 × 2 rectangular array of circular pillars is analyzed theoretically and verified with experiments. Nanoliter-to-microliter volumes of liquids are patterned into various shapes by arranging the pillars based on the analysis. Furthermore, an array of geometrically modified pillars can capture approximately 8000 droplets on a large substrate (55 mm × 55 mm) in one step. Given the simplistic method of wipe patterning, the proposed platform can be utilized in both manual benchtop and automated settings. We will provide proof of concept experiments of single colony isolation using nanoliter-scale liquid patterning and of human angiogenic vessel formation using sequential patterning of microliter-scale liquids.
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- 2018
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7. Engaging end-users in intervention research study design.
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Martin MA, Press VG, Erwin K, Margellos-Anast H, Ignoffo S, McMahon KS, Mosnaim G, Ramsay J, and Paik SM
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- Caregivers, Community Health Workers, Focus Groups, Humans, Asthma, Clinical Trials as Topic, Community Participation, Emergency Service, Hospital, Research Design
- Abstract
Objective: Coordinated Healthcare Interventions for Childhood Asthma Gaps in Outcomes (CHICAGO) Plan is a 3-arm multicenter pragmatic trial to evaluate asthma interventions in high-risk Chicago children presenting to emergency departments (ED) with asthma. A formative evaluation with end-users to provide input into the trial design and outcome instruments was conducted prior to trial initiation., Methods: A multi-level data gathering framework from the field of design and standard qualitative methods was employed. This included one focus group with asthma Community Health Workers (N = 8), two focus groups with caregivers of children with asthma (N = 9), in-home interviews with caregivers (N = 9), key informant interviews at six EDs and outpatient clinical sites (N = 19), and ED tours and observations (N = 6). Data were presented, discussed, and organized into themes., Results: Data indicated that changes to the study design and discharge tool were warranted. A key insight was that ED discharge protocols typically place patient education at a single inopportune time, as families are preparing to leave the ED. At this point in time, families are less receptive to education due to fatigue and a desire to expedite the discharge process. The trial design was modified to reposition the discharge asthma plan to occur at earlier "teachable moments." Delivery of the asthma discharge plan was assigned to study-employed ED coordinators instead of ED providers and staff. Other potential challenges to study recruitment and implementation were raised and addressed., Conclusions: Engagement of end-users in the design phase of implementation research is critical to improve research feasibility and relevance.
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- 2018
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8. Vibration-induced stress priming during seed culture increases microalgal biomass in high shear field-cultivation.
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Paik SM, Jin E, Sim SJ, and Jeon NL
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- Biomass, Vibration, Bioreactors, Microalgae
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Vibrational wave treatment has been used to increase proliferation of microalgae. When directly applied at large scale, however, turbulence can offset positive effects of vibration on microalgae proliferation. Moreover, severe hydrodynamic shear fields in the bioreactor decrease cell viability that detrimentally influence maximum yieldable biomass. In this study, vibration pretreatment (between 10-30 Hz and 0.15-0.45 G) was used to prime the cells for enhanced biomass. When exposed to 10 Hz at 0.15 G for 72 h and inoculated in baffled flasks of large shear fields (0.292 Pa for the average wall shear force (aveWSF) and 184 s
-1 for the average shear strain rate (aveSSR)), microalgae showed 27% increase in biomass as well as 39% increase in corresponding amount of heterologous protein (i.e. GFP-3HA). Our results show that stress primed microalgae with vibrations can lead to improved proliferation that results in increased biomass production at industrial scale bioprocesses., (Copyright © 2018. Published by Elsevier Ltd.)- Published
- 2018
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9. Microfluidic perfusion bioreactor for optimization of microalgal lipid productivity.
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Paik SM, Sim SJ, and Jeon NL
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- Biomass, Bioreactors, Lipids biosynthesis, Microalgae metabolism, Microfluidics
- Abstract
Nutrient deprivation in a batch process induces microbes to produce secondary metabolites while drastically constraining cellular growth. A microfluidic continuous perfusion system was designed and tested to culture microalgae, Chlamydomonas reinhardtii, under constant nutrient concentration slightly lower than normal condition. When cultured in 7.5%/7.5% of NH
4 + /PO4 2 - , C. reinhardtii showed a 2.4-fold increase in TAG production with a 3.5-fold increase in biomass compared to level obtained under an only NH4 + depleted condition. The microfluidic continuous perfusion bioreactor with steady continuous nutrient flow can be used to optimize conditions for enhancing secondary metabolite production and increasing microbial biomass., (Copyright © 2017 Elsevier Ltd. All rights reserved.)- Published
- 2017
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10. Rapid large area fabrication of multiscale through-hole membranes.
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Tahk D, Paik SM, Lim J, Bang S, Oh S, Ryu H, and Jeon NL
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- Cell Culture Techniques, Equipment Design, Microalgae cytology, Membranes, Artificial, Microfluidic Analytical Techniques instrumentation, Single-Cell Analysis instrumentation, Single-Cell Analysis methods
- Abstract
There are many proposed mechanisms by which single cells can be trapped; among them is the through-hole membrane for the characterization of individual microorganisms. Due to the small scale of the fabricated pores, the construction of through-hole membranes on a large scale and with relatively large areas faces many difficulties. This paper describes novel fabrication methods for a large-area, freestanding micro/nano through-hole membrane constructed from versatile membrane materials using through-hole membranes on a microfluidic chip (THMMC). This process can rapidly (<20 min) fabricate membranes with high fidelity multiscale hole size without residual layers. The through-hole site was easily customizable from the micro to the nanoscale, with a low or high aspect ratio giving rise to reliable membranes. Also, the rigidity and biocompatibility of the through-hole membrane are easily tunable by simple injection of versatile membrane materials to obtain a large area (up to 3600 mm
2 ). Membranes produced in this manner were then applied as a proof of concept for the isolation, cultivation, and quantification of individual micro-algal cells for selection with respect to the growth rate, while controlling the quorum sensing mediated metabolic and proliferative changes.- Published
- 2017
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11. Care transition interventions for children with asthma in the emergency department.
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Martin MA, Press VG, Nyenhuis SM, Krishnan JA, Erwin K, Mosnaim G, Margellos-Anast H, Paik SM, Ignoffo S, and McDermott M
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- Child, Evidence-Based Practice, Humans, Patient Outcome Assessment, Primary Health Care, Self Care, United States, Asthma epidemiology, Emergency Service, Hospital, Patient Transfer
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The emergency department (ED) is a critical point of identification and treatment for some of the most high-risk children with asthma. This review summarizes the evidence regarding care transition interventions originating in the ED for children with uncontrolled asthma, with a focus on care coordination and self-management education. Although many interventions on care transition for pediatric asthma have been tested, only a few were actually conducted in the ED setting. Most of these targeted both care coordination and self-management education but ultimately did not improve attendance at follow-up appointments with primary care providers, improve asthma control, or reduce health care utilization. Conducting any ED-based intervention in the current environment is challenging because of the many demands on ED providers and staff, poor communication within and outside of the medical sector, and caregiver/patient burden. The evidence to date suggests that ED care transition interventions should consider expanding beyond the ED to bridge the multiple sectors children with asthma navigate, including health care settings, homes, schools, and community spaces. Patient-centered approaches may also be important to ensure adequate intervention design, enrollment, retention, and evaluation of outcomes important to children and their families., (Copyright © 2016 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)
- Published
- 2016
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12. Total Anomalous Coronary Venous Return: Strategic Planning in Atrial Fibrillation Ablation.
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Crimm HA, Paik SM, Needleman M, and Villines TC
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- 2016
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13. Cooperative optical response of 2D dense lattices with strongly correlated dipoles.
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Yoo SM and Paik SM
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We study light propagation in dense low-temperature atoms on two-dimensional (2D) square and kagome lattices using a basically exact large-scale numerical computations. In the limit of weak laser intensity, shifts of the resonance line are shown in homogeneously broadened stationary samples with high atom densities, whereas the shifts are not shown in the samples with low densities. We obtain the dependence of shifts on interatomic spacing for square lattices with the various numbers of atoms, and our numerical results are in good agreement with shifts derived using a 2D isotropic infinite lattice model and experimental data for nanometric-thickness atomic ensembles in the literature.
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- 2016
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14. Capillarity Guided Patterning of Microliquids.
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Kang M, Park W, Na S, Paik SM, Lee H, Park JW, Kim HY, and Jeon NL
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- Capillaries, Equipment Design, Equipment Failure Analysis, Cell Separation instrumentation, Gels chemistry, Microfluidics instrumentation, Molecular Imprinting instrumentation, Printing, Three-Dimensional instrumentation, Solutions chemistry
- Abstract
Soft lithography and other techniques have been developed to investigate biological and chemical phenomena as an alternative to photolithography-based patterning methods that have compatibility problems. Here, a simple approach for nonlithographic patterning of liquids and gels inside microchannels is described. Using a design that incorporates strategically placed microstructures inside the channel, microliquids or gels can be spontaneously trapped and patterned when the channel is drained. The ability to form microscale patterns inside microfluidic channels using simple fluid drain motion offers many advantages. This method is geometrically analyzed based on hydrodynamics and verified with simulation and experiments. Various materials (i.e., water, hydrogels, and other liquids) are successfully patterned with complex shapes that are isolated from each other. Multiple cell types are patterned within the gels. Capillarity guided patterning (CGP) is fast, simple, and robust. It is not limited by pattern shape, size, cell type, and material. In a simple three-step process, a 3D cancer model that mimics cell-cell and cell-extracellular matrix interactions is engineered. The simplicity and robustness of the CGP will be attractive for developing novel in vitro models of organ-on-a-chip and other biological experimental platforms amenable to long-term observation of dynamic events using advanced imaging and analytical techniques., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2015
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15. Live cell imaging compatible immobilization of Chlamydomonas reinhardtii in microfluidic platform for biodiesel research.
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Park JW, Na SC, Nguyen TQ, Paik SM, Kang M, Hong D, Choi IS, Lee JH, and Jeon NL
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- Lipids, Mitosis physiology, Reproducibility of Results, Biofuels, Cells, Immobilized cytology, Chlamydomonas reinhardtii cytology, Chlamydomonas reinhardtii metabolism, Image Processing, Computer-Assisted methods, Microfluidic Analytical Techniques methods, Single-Cell Analysis methods
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This paper describes a novel surface immobilization method for live-cell imaging of Chlamydomonas reinhardtii for continuous monitoring of lipid droplet accumulation. Microfluidics allows high-throughput manipulation and analysis of single cells in precisely controlled microenvironment. Fluorescence imaging based quantitative measurement of lipid droplet accumulation in microalgae had been difficult due to their intrinsic motile behavior. We present a simple surface immobilization method using gelatin coating as the "biological glue." We take advantage of hydroxyproline (Hyp)-based non-covalent interaction between gelatin and the outer cell wall of microalgae to anchor the cells inside the microfluidic device. We have continuously monitored single microalgal cells for up to 6 days. The immobilized microalgae remain viable (viability was comparable to bulk suspension cultured controls). When exposed to wall shear stress, most of the cells remain attached up to 0.1 dyne/cm(2) . Surface immobilization allowed high-resolution, live-cell imaging of mitotic process in real time-which followed previously reported stages in mitosis of suspension cultured cells. Use of gelatin coated microfluidics devices can result in better methods for microalgae strain screening and culture condition optimization that will help microalgal biodiesel become more economically viable., (© 2014 Wiley Periodicals, Inc.)
- Published
- 2015
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16. Rim15-dependent activation of Hsf1 and Msn2/4 transcription factors by direct phosphorylation in Saccharomyces cerevisiae.
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Lee P, Kim MS, Paik SM, Choi SH, Cho BR, and Hahn JS
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- Amino Acid Transport Systems genetics, Amino Acid Transport Systems metabolism, Gene Expression Regulation, Fungal, Histone Demethylases metabolism, Intracellular Signaling Peptides and Proteins metabolism, Phosphorylation, Protein Processing, Post-Translational, Protein Serine-Threonine Kinases metabolism, RNA Stability, Saccharomyces cerevisiae genetics, Saccharomyces cerevisiae Proteins genetics, Transcriptional Activation, DNA-Binding Proteins metabolism, Heat-Shock Proteins metabolism, Protein Kinases metabolism, Saccharomyces cerevisiae enzymology, Saccharomyces cerevisiae Proteins metabolism, Transcription Factors metabolism
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Rim15 kinase, a downstream effector of PKA and TORC1 signaling pathways, initiates the quiescent program upon nutrient starvation via induction of genes whose expression depends on transcription factors Msn2, Msn4, and Gis1. Here, we demonstrate that Rim15 also induces expression of Hsf1 target genes upon glucose depletion by both transcriptional activation and stabilization of the transcripts. Rim15 phosphorylates Hsf1 in vitro, suggesting that Rim15 might directly activate Hsf1. In addition, Igo1 and Igo2, Rim15 substrate proteins involved in mRNA stabilization, regulate mRNA levels of Hsf1 target genes. We also show that Rim15 can phosphorylate Msn2, but not Gis1, in vitro, implying different mechanisms for the activation of these transcription factors., (Copyright © 2013 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.)
- Published
- 2013
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17. Effect of topography of an electrospun nanofiber on modulation of activity of primary rat astrocytes.
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Min SK, Kim SH, Kim CR, Paik SM, Jung SM, and Shin HS
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- Animals, Astrocytes cytology, Astrocytes physiology, Cell Adhesion, Cell Survival, Cells, Cultured, Glial Fibrillary Acidic Protein metabolism, Nanofibers chemistry, Polyesters chemistry, Rats, Rats, Sprague-Dawley, Astrocytes drug effects, Nanofibers ultrastructure, Polyesters pharmacology
- Abstract
Several biomaterials for neural tissue engineering have recently been proposed for regeneration of damaged tissue and promotion of axonal guidance following CNS injury. When implanted into damaged nerve tissue, biomaterials should favorably induce cell infiltration and axonal guiding while suppressing inflammation. Nanofiber scaffolds are regarded as adequate materials to meet the above requirements; however, most studies of these materials conducted to date have targeted neuronal cells, not glial cells, despite their important function in the injured CNS. In this study, an electrospun nanofibrous scaffold of polycaprolactone (PCL) was investigated with respect to its topographic effects on astrocyte behavior and expression of GFAP. The results revealed that the PCL nanofiber topograghy promoted adhesion, but GFAP expression was down-regulated, leading to reduced astrocytes activity. Taken together, these results indicate that the topographic structure of electrospun nanofibers provides a scaffold that is favorable to neural regeneration via alleviation of astrogliosis., (Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.)
- Published
- 2013
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18. Regulation of yeast Yak1 kinase by PKA and autophosphorylation-dependent 14-3-3 binding.
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Lee P, Paik SM, Shin CS, Huh WK, and Hahn JS
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- 14-3-3 Proteins metabolism, Cell Nucleus metabolism, Intracellular Signaling Peptides and Proteins antagonists & inhibitors, Intracellular Signaling Peptides and Proteins chemistry, Models, Biological, Phosphorylation, Phosphoserine metabolism, Phosphothreonine, Protein Binding, Protein Serine-Threonine Kinases antagonists & inhibitors, Protein Serine-Threonine Kinases chemistry, Protein Structure, Tertiary, Protein Transport, Saccharomyces cerevisiae cytology, Saccharomyces cerevisiae Proteins antagonists & inhibitors, Saccharomyces cerevisiae Proteins chemistry, Cyclic AMP-Dependent Protein Kinases metabolism, Intracellular Signaling Peptides and Proteins metabolism, Protein Serine-Threonine Kinases metabolism, Saccharomyces cerevisiae enzymology, Saccharomyces cerevisiae Proteins metabolism
- Abstract
Yak1 is a member of an evolutionarily conserved family of Ser/Thr protein kinases known as dual-specificity Tyr phosphorylation-regulated kinases (DYRKs). Yak1 was originally identified as a growth antagonist, which functions downstream of Ras/PKA signalling pathway. It has been known that Yak1 is phosphorylated by PKA in vitro and is translocated to the nucleus upon nutrient deprivation. However, the regulatory mechanisms for Yak1 activity and localization are largely unknown. In the present study, we investigated the role of PKA and Bmh1, a yeast 14-3-3 protein, in regulation of Yak1. We demonstrate that PKA-dependent phosphorylation of Yak1 on Ser295 and two minor sites inhibits nuclear localization of Yak1. We also show that intramolecular autophosphorylation on at least four Ser/Thr residues in the non-catalytic N-terminal domain is required for full kinase activity of Yak1. The most potent autophosphorylation site, Thr335, plays an essential role for Bmh1 binding in collaboration with a yet unidentified second binding site in the N-terminal domain. Bmh1 binding decreases the catalytic activity of Yak1 without affecting its subcellular localization. Since the binding of 14-3-3 proteins to Yak1 coincides with PKA activity, such regulatory mechanisms might allow cytoplasmic retention of an inactive form of Yak1 under high glucose conditions., (© 2010 Blackwell Publishing Ltd.)
- Published
- 2011
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19. Involvement of ceramide in ethanol-induced apoptotic neurodegeneration in the neonatal mouse brain.
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Saito M, Chakraborty G, Hegde M, Ohsie J, Paik SM, Vadasz C, and Saito M
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- Animals, Antimetabolites pharmacology, Blotting, Western, Brain pathology, Brain Chemistry drug effects, Caspase 3 metabolism, Cycloserine pharmacology, Enzyme Activation drug effects, Enzyme Inhibitors pharmacology, Immunohistochemistry, Lipid Metabolism physiology, Mice, Mice, Inbred C57BL, Neurons pathology, Serine C-Palmitoyltransferase antagonists & inhibitors, Serine C-Palmitoyltransferase metabolism, Animals, Newborn physiology, Apoptosis drug effects, Central Nervous System Depressants pharmacology, Ceramides physiology, Ethanol pharmacology, Nerve Degeneration chemically induced, Nerve Degeneration pathology
- Abstract
Acute administration of ethanol to 7-day-old mice is known to cause robust apoptotic neurodegeneration in the brain. Our previous studies have shown that such ethanol-induced neurodegeneration is accompanied by increases in lipids, including ceramide, triglyceride (TG), cholesterol ester (ChE), and N-acylphosphatidylethanolamine (NAPE) in the brain. In this study, the effects of ethanol on lipid profiles as well as caspase 3 activation were examined in the cortex, hippocampus, cerebellum, and inferior colliculus of the postnatal day 7 mouse brain. We found that the cortex, hippocampus, and inferior colliculus, which showed substantial caspase 3 activation by ethanol, manifested significant elevations in ceramide, TG, and NAPE. In contrast, the cerebellum, with the least caspase 3 activation, failed to show significant changes in ceramide and TG, and exhibits much smaller increases in NAPE than other brain regions. Ethanol-induced increases in ChE were observed in all brain regions tested. Inhibitors of serine palmitoyltransferase effectively blocked ethanol-induced caspase 3 activation as well as elevations in ceramide, ChE, and NAPE. Immunohistochemical studies indicated that the expression of serine palmitoyltransferase was mainly localized in neurons and was enhanced in activated caspase 3-positive neurons generated by ethanol. These results indicate that de novo ceramide synthesis has a vital role in ethanol-induced apoptotic neurodegeneration in the developing brain., (© 2010 The Authors. Journal Compilation © 2010 International Society for Neurochemistry.)
- Published
- 2010
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20. Tau phosphorylation and cleavage in ethanol-induced neurodegeneration in the developing mouse brain.
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Saito M, Chakraborty G, Mao RF, Paik SM, Vadasz C, and Saito M
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- Amino Acid Sequence, Animals, Blotting, Western, Brain enzymology, Brain growth & development, Brain metabolism, Cells, Cultured, Glycogen Synthase Kinase 3 metabolism, Glycogen Synthase Kinase 3 beta, Hydrolysis, Immunohistochemistry, Mice, Mice, Inbred C57BL, Phosphorylation, Brain drug effects, Ethanol toxicity, tau Proteins metabolism
- Abstract
Previous studies indicated that ethanol-induced neurodegeneration in postnatal day 7 (P7) mice, widely used as a model for the fetal alcohol spectrum disorders, was accompanied by glycogen synthase kinase-3beta (GSK-3beta) and caspase-3 activation. Presently, we examined whether tau, a microtubule associated protein, is modified by GSK-3beta and caspase-3 in ethanol-treated P7 mouse forebrains. We found that ethanol increased phosphorylated tau recognized by the paired helical filament (PHF)-1 antibody and by the antibody against tau phosphorylated at Ser199. Ethanol also generated tau fragments recognized by an antibody against caspase-cleaved tau (C-tau). C-tau was localized in neurons bearing activated caspase-3 and fragmented nuclei. Over time, cell debris and degenerated projections containing C-tau appeared to be engulfed by activated microglia. A caspase-3 inhibitor partially blocked C-tau formation. Lithium, a GSK-3beta inhibitor, blocked ethanol-induced caspase-3 activation, phosphorylated tau elevation, C-tau formation, and microglial activation. These results indicate that tau is phosphorylated by GSK-3beta and cleaved by caspase-3 during ethanol-induced neurodegeneration in the developing brain.
- Published
- 2010
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21. Pathologic findings from the National Surgical Adjuvant Breast Project (NSABP) Protocol B-17. Five-year observations concerning lobular carcinoma in situ.
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Fisher ER, Costantino J, Fisher B, Palekar AS, Paik SM, Suarez CM, and Wolmark N
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- Breast Neoplasms radiotherapy, Breast Neoplasms surgery, Carcinoma in Situ radiotherapy, Carcinoma in Situ surgery, Carcinoma, Lobular radiotherapy, Carcinoma, Lobular surgery, Cohort Studies, Female, Humans, Mastectomy, Middle Aged, Neoplasm Recurrence, Local, Breast Neoplasms pathology, Carcinoma in Situ pathology, Carcinoma, Lobular pathology
- Abstract
Background: Extant information reveals inconsistencies concerning the natural history, pathologic features, and treatment of lobular carcinoma in situ (LCIS) of the breast. It is uncertain whether these are related to the methods of study, diagnostic criteria employed, relative paucity of cases, or varying lengths of follow-up., Methods: The cohort was comprised of 182 women with LCIS who were enrolled in National Surgical Adjuvant Breast Project (NSABP) Protocol B-17 but received no treatment other than lumpectomy. Nineteen pathologic features were assessed and related to ipsilateral breast tumor recurrence (IBTR) and contralateral breast tumor recurrence (CBTR) at a mean time on study of 5 years., Results: Thirteen IBTR and 4 CBTR, including 1 instance of bilateral recurrence, were observed. All IBTR occurred in the same quadrant as the index LCIS. All 4 (2.2%) IBTR that were invasive cancers were of the lobular type, as was 1 of the 2 (1.1%) CBTR that were invasive. The other was a mucinous carcinoma. Three (1.6%) IBTR were pure ductal carcinoma in situ (DCIS) and another was accompanied by LCIS. One instance of CBTR was also comprised of DCIS and LCIS. The remaining five IBTR and one CBTR were LCIS only. The only pathologic parameter found to be significantly predictive for invasive IBTR and DCIS was type 3 and, to a lesser extent, type 2 LCIS. Some heretofore unrecognized or little appreciated pathologic features of LCIS are noted. Ancillary histochemical findings strongly implicate the derivation of LCIS from ductal or secretory cells rather than "new cells" or myoepithelial elements. All examples tested were found to be c-erb B-2 negative, universally diploid with normoproliferative DNA content, and estrogen receptor and progesterone receptor positive. No other events related to the breast were encountered., Conclusions: The number of events observed in this large cohort of patients with LCIS is markedly less than that noted by others after a comparable period of follow-up. Possible reasons for this dichotomy, including differences in patient characteristics, diagnostic criteria, and status of resection margins, are discussed. Considerations are also offered to support the view that LCIS may exhibit precursor activity as well as represent a risk factor (the term marker is literally inaccurate). In this light, the designation LCIS rather than lobular neoplasia is preferred. These preliminary findings and historical information presented in this study fail to provide any reason to perform mastectomy on patients with LCIS.
- Published
- 1996
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22. Local epitaxial growth of CuO films on MgO.
- Author
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Catana A, Locquet JP, Paik SM, and Schuller IK
- Published
- 1992
- Full Text
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23. Method of determining tip structure in atomic force microscopy.
- Author
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Paik SM, Kim S, and Schuller IK
- Published
- 1991
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24. Surface kinetics and roughness on microstructure formation in thin films.
- Author
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Paik SM, Kim S, Schuller IK, and Ramirez R
- Published
- 1991
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25. New calculational method for epitaxial energy: Application to an axial commensurate interface.
- Author
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Paik SM and Schuller IK
- Published
- 1990
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26. Prognostic significance of eosinophils and mast cells in rectal cancer: findings from the National Surgical Adjuvant Breast and Bowel Project (protocol R-01).
- Author
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Fisher ER, Paik SM, Rockette H, Jones J, Caplan R, and Fisher B
- Subjects
- Cell Count, Female, Humans, Neoplasm Staging, Prognosis, Rectal Neoplasms mortality, Time Factors, Eosinophils pathology, Mast Cells pathology, Rectal Neoplasms pathology
- Abstract
The numbers of eosinophils and mast cells observed at the tumor border of 331 rectal cancers from patients enrolled in the National Surgical Adjuvant Breast and Bowel Project (NSABP), protocol R-01, were correlated according to overall survival rate, as well as Dukes' stage, tumor differentiation, nodal status, degree of lymphoid and stromal reactions, sex, and age. Life table plots disclosed a significantly better overall survival rate when ten or more eosinophils per 30 oil immersion fields were found. However, the numbers of eosinophils were strongly associated with Dukes' stage and, when life table plots were adjusted for Dukes' stage, this relationship to survival rate was not evident. On the other hand, overall survival rate was significantly higher in patients in whom 0 to three mast cells per 30 oil immersion fields were found than in those patients in whom four or more mast cells were found. This relationship persisted even when life table plots were adjusted for treatment, Dukes' stage, or nodal status, and indicated that the number of mast cells further defined survival rate among patients exhibiting Dukes' A, B, and C stages. It is concluded that numbers of eosinophils and mast cells may play a role in the natural history of rectal cancer but only the latter represents a prognostic parameter independent of Dukes' stage or nodal status. The mechanism whereby mast cells may exert this effect is at present unknown.
- Published
- 1989
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27. Atomistic growth mechanisms for the molecular-beam epitaxy of a model system.
- Author
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Paik SM and Das Sarma S
- Published
- 1989
- Full Text
- View/download PDF
28. Pathologic findings from the National Surgical Adjuvant Breast Project (protocol 6). I. Intraductal carcinoma (DCIS).
- Author
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Fisher ER, Sass R, Fisher B, Wickerham L, and Paik SM
- Subjects
- Basement Membrane pathology, Biopsy, Female, Humans, Middle Aged, Neoplasm Invasiveness, Neoplasm Recurrence, Local, Breast Neoplasms pathology, Carcinoma, Intraductal, Noninfiltrating pathology
- Abstract
Seventy-eight examples of intraductal carcinoma (DCIS) were identified after pathologic review of 2072 specimens obtained from National Surgical Adjuvant Breast Project protocol 6. This randomized clinical trial compares the therapeutic merit of total mastectomy (TM) with lumpectomy (L), with (LX) and without (LO) postoperative irradiation. All patients were subjected to axillary lymph node dissection. Seven (14%) of the 51 patients with DCIS treated by L exhibited breast recurrence within or close to the site of the initial lesion 4 to 53 months (average, 16 months) after L. Only 2 (7%) of these events occurred in the 29 women treated by LX, as opposed to 23% in the LO group. No pathologic features were noticed that might have been considered predictive of local breast recurrence. The three DCIS recurrences and the four invasive forms noted are considered to represent overlooked or incompletely excised foci of cancer because of the multifocality (not multicentricity) of some breast cancers. The possibility that DCIS may represent a marker of risk for the development of cancer rather than a precursor lesion per se is suggested. Despite apparent difficulties in the pathologic diagnosis of DCIS as well as uncertainty concerning its natural history, no evidence was found to indicate that it represents a more ominous disease than invasive cancer. Indeed, treatment failure occurred in only one patient treated by LX and a similar number subjected to TM (4% versus 2%). Although these observations are short term (average follow-up, 39 months), estimates of the probability of local recurrence or survival suggest that they will not be significantly altered after longer periods of surveillance. Thus, there are no compelling reasons why DCIS may not be treated in a cosmetically acceptable manner by LX. A randomized clinical trial addressing this issue is now in progress.
- Published
- 1986
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29. Oxidative activation and inactivation of the carcinogen 2-acetylaminofluorene by various purified cytochromes P-450 from 3-methylcholanthrene pretreated rats.
- Author
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Lotlikar PD, Pandey RN, Clearfield MS, and Paik SM
- Subjects
- Animals, Biotransformation drug effects, Enzyme Induction drug effects, Hydroxylation, Immunodiffusion, Inactivation, Metabolic drug effects, Male, Oxidation-Reduction drug effects, Rats, Rats, Inbred Strains, 2-Acetylaminofluorene metabolism, Cytochrome P-450 Enzyme System metabolism, Methylcholanthrene pharmacology, Microsomes, Liver enzymology
- Abstract
Ring- and N-hydroxylations of 2-acetylaminofluorene (AAF) have been examined in a reconstituted system with 4 purified hepatic microsomal cytochromes P-450 isolated from 3-methylcholanthrene (MC)-pretreated rats. Among these 4 isozymes, P-450D showed the most activity whereas P-450C was devoid of any activity; two other P-450s exhibited moderate activity. These and Ouchterlony's double diffusion analyses suggest involvement of multiple cytochromes P-450 in AAF oxidations.
- Published
- 1984
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30. Antibody inhibition of oxidative activation and inactivation of the carcinogen 2-acetylaminofluorene by purified hepatic cytochrome P-450 from 3-methylcholanthrene pretreated rats.
- Author
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Pandey RN, Clearfield MS, Paik SM, and Lotlikar PD
- Subjects
- Animals, Antigen-Antibody Complex, Biotransformation, Hydroxylation, Isoenzymes antagonists & inhibitors, Male, Microsomes, Liver drug effects, Oxidation-Reduction, Rats, Rats, Inbred Strains, 2-Acetylaminofluorene metabolism, Antibodies, Cytochrome P-450 Enzyme Inhibitors, Methylcholanthrene toxicity, Microsomes, Liver enzymology, NADPH-Ferrihemoprotein Reductase metabolism
- Abstract
Immunochemical studies on metabolic N- and ring hydroxylation of 2-acetylaminofluorene (AAF) were performed with total cytochrome P-450 isozymes and with highly purified P-450 D isozyme isolated from liver microsomes from 3-methylcholanthrene (MC)-pretreated rats. In a reconstituted system with rat P-450 D, addition of antibodies against beta-naphthoflavone (BNF) induced rat P-450 B at 15 mg IgG/nmol P-450 inhibited both oxidations completely. With total P-450 isozymes in a reconstituted system, antibody against BNF-rat-P-450 B at 20 mg IgG/nmol P-450 inhibited both oxidations up to 70-80% only. At these concentrations, preimmune antibody or phenobarbital (PB) induced antibody against rat-P-450 B showed no inhibition of AAF oxidations. These results suggest that P-450 D is the predominant cytochrome P-450 isozyme responsible for AAF N- and ring-oxidations in liver microsomes from MC-pretreated rats. Other P-450 isozymes are also suggested to be involved in AAF oxidations.
- Published
- 1983
- Full Text
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31. Dynamical simulation of molecular-beam epitaxial growth of a model crystal.
- Author
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Paik SM and Das Sarma S
- Published
- 1989
- Full Text
- View/download PDF
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