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Search Results: 1 - 10 of 468196 matches for " A-Reum Park "
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Dual Effect of Exogenous Nitric Oxide on Neuronal Excitability in Rat Substantia Gelatinosa Neurons
A-Reum Park,Hae In Lee,Dejidnorov Semjid,Do Kyung Kim,Sang Woo Chun
Neural Plasticity , 2014, DOI: 10.1155/2014/628531
Abstract: Nitric oxide (NO) is an important signaling molecule involved in nociceptive transmission. It can induce analgesic and hyperalgesic effects in the central nervous system. In this study, patch-clamp recording was used to investigate the effect of NO on neuronal excitability in substantia gelatinosa (SG) neurons of the spinal cord. Different concentrations of sodium nitroprusside (SNP; NO donor) induced a dual effect on the excitability of neuronal membrane: 1?mM of SNP evoked membrane hyperpolarization and an outward current, whereas 10?μM induced depolarization of the membrane and an inward current. These effects were prevented by hemoglobin and 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt (c-PTIO) (NO scavengers), phenyl N-tert-butylnitrone (PBN; nonspecific reactive oxygen species scavenger), and through inhibition of soluble guanylyl cyclase (sGC). Pretreatment with n-ethylmaleimide (NEM; thiol-alkylating agent) also decreased effects of both 1?mM and 10?μM SNP, suggesting that these responses were mediated by direct S-nitrosylation. Charybdotoxin (CTX) and tetraethylammonium (TEA) (large-conductance Ca2+-activated K+ channel blockers) and glybenclamide (ATP-sensitive K+ channel blocker) decreased SNP-induced hyperpolarization. La3+ (nonspecific cation channel blocker), but not Cs+ (hyperpolarization-activated K+ channel blocker), blocked SNP-induced membrane depolarization. In conclusion, NO dually affects neuronal excitability in a concentration-dependent manner via modification of various K+ channels. 1. Introduction Nitric oxide (NO) is a pivotal signaling molecule involved in many diverse developmental and physiological processes in the mammalian nervous system [1–3]. NO is biosynthesized from L-arginine by specific neuronal and non-neuronal forms of NO synthase [4, 5]. NO donors as well as endogenously produced NO play a role in many physiological processes, including smooth muscle relaxation, cellular proliferation, apoptosis, neurotransmitter release, and cell differentiation [6]. NO-induced effects are commonly mediated through the following processes: increased cGMP production upon activation of NO-sensitive soluble guanylyl cyclase (sGC), S-nitrosylation, tyrosine nitration, and NO interaction with superoxide ( ) to form peroxynitrite (ONOO?) [1, 7, 8]. Oxidative stress due to reactive oxygen species (ROS) such as , hydrogen peroxide (H2O2), NO, and ONOO? interferes with normal cell function and can cause cell damage. Moreover, ROS is associated with chronic pain, particularly neuropathic and
Neuronal Synapse Formation Induced by Microglia and Interleukin 10
So-Hee Lim, Eunha Park, Boram You, Youngseob Jung, A-Reum Park, Sung Goo Park, Jae-Ran Lee
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0081218
Abstract: Recently, it was found that microglia regulated synaptic remodeling of the developing brain, but their mechanisms have not been well understood. In this study, the action of microglia on neuronal synapse formation was investigated, and the primary target of microglial processes was discovered. When the developing microglia were applied to cultured hippocampal neurons without direct contact, the numbers of dendritic spines and excitatory and inhibitory synapses significantly increased. In order to find out the main factor for synaptic formation, the effects of cytokines released from microglia were examined. When recombinant proteins of cytokines were applied to neuronal culture media, interleukin 10 increased the numbers of dendritic spines in addition to excitatory and inhibitory synapses. Interestingly, without external stimuli, the amount of interleukin 10 released from the intact microglia appeared to be sufficient for the induction of synaptic formation. The neutralizing antibodies of interleukin 10 receptors attenuated the induction of the synaptic formation by microglia. The expression of interleukin 10 receptor was newly found in the hippocampal neurons of early developmental stage. When interleukin 10 receptors on the hippocampal neurons were knocked down with specific shRNA, the induction of synaptic formation by microglia and interleukin 10 disappeared. Pretreatment with lipopolysaccharide inhibited microglia from inducing synaptic formation, and interleukin 1β antagonized the induction of synaptic formation by interleukin 10. In conclusion, the developing microglia regulated synaptic functions and neuronal development through the interactions of the interleukin 10 released from the microglia with interleukin 10 receptors expressed on the hippocampal neurons.
Weight Loss and Nutrient Dynamics during Leaf Litter Decomposition of Quercus variabilis and Pinus densiflora at Mt. Worak National Park
Namgung, Jeong,A-Reum Han,Hyeong-Tae Mun
Journal of Ecology and Field Biology , 2008,
Abstract: Weight loss and nutrient dynamics of oak and pine leaf litter during decomposition were investigatedfrom December 2005 through June 2008 at Mt. Worak National Park as a part of National Long-TermEcological Research Program in Korea. The decay constant (k) of oak and pine leaf litter were 0.314 and 0.217,respectively. After 30 months decomposition, remaining weight of oak and pine leaf litter was 45.5% and 58.1%,respectively. Initial C/N ratio of oak and pine leaf litter was 53.4 and 153.0, respectively. Carbon % of initial oakand pine leaf litter was similar with each other; however, nitrogen content of initial oak leaf litter (0.85%) wasgreater than that of initial pine leaf litter (0.33%). N and P concentration in both decomposing leaf litter increasedsignificantly during decomposition. There was no net N and P mineralization period in decomposing pine leaflitter. K, Ca and Mg concentration in both decomposing leaf litter showed different pattern with those of N andP. After 30 months decomposition, remaining nutrients in oak and pine leaf litter were 97.7 and 216.2% for N,123.2 and 216.5% for P, 39.3 and 44.8% for K, 47.9 and 40.6% for Ca, 30.7 and 51.2% for Mg, respectively.
Distribution of Organic Carbon in Pitch Pine Plantation in Kongju, Korea
Han, A-Reum,Hyeong-Tae Mun
Journal of Ecology and Field Biology , 2009,
Abstract: Organic carbon (OC) distribution in 32-year-old pitch pine plantation at Mt. Hotae in Kongju, Korea,was studied from August 2007 to July 2008. In order to investigate the OC distribution, OC in plant biomass, litterfall,litter layer on forest floor, and soil within 50cm depth were estimated. The density of P. rigida plantation was3,200 trees/ha, average DBH was 18.7 ± 5.53 cm and average tree height was 11.1 ± 1.85 m. Organic carbonstored in plant biomass, litterlayer on forest floor and soil in 2008 was 89.46 ton C/ha (46.09%), 4.32 ton C/ha(2.23%) and 100.32 ton C ha-1 50cm-depth-1 (51.68%), respectively. Amount of OC returned to forest floor vialitterfall was 2.21 ton C ha-1 yr-1. Total amount of OC stored in this P. rigida plantation was 194.1 ton C/ha.Net increase of OC in above- and below-ground biomass in this pitch pine plantation was 4.82 ton C ha-1 yr-1.
Practical Guide to Using Cryoprotectants in Biological Sample Preparation at Cryogenic temperature for Electron Microscopic Studies
A-Reum Je,Kyoung Hwan Lee,Heesu Chae,Soo Jin Kim
Journal of Analytical Science & Technology , 2011,
Abstract: Cryo-fixation enables the preservation of the fine structures of intracellular organelles in a condition that is as close to their native state as possible compared with chemical fixation and room temperature processing. Fixation is the initial step for biological sample preparation in electron microscopy. This step is critically important because the goals of electron microscopic observation are fundamentally dependent on well-preserved specimens resulting from this fixation. In the present work, key components of cryo-fixation, cryoprotectants, are tested with various cell types of interest. The results show that dextran can be easily adapted for use with animal cells and cyanobacteria, whereas 1-hexadecene is applicable to plant and yeast cells. The current report provides useful information on the preparation of cryo-fixed biological specimens using high pressure freezing and freeze-substitution aimed at electron microscopic observation.
Rate of vertical transmission of human papillomavirus from mothers to infants: Relationship between infection rate and mode of delivery
Hyun Park, Si Won Lee, In Ho Lee, Hyun Mee Ryu, A Reum Cho, Yong Soon Kang, Sung Ran Hong, Sung Soon Kim, Seok Ju Seong, Son Moon Shin, Tae Jin Kim
Virology Journal , 2012, DOI: 10.1186/1743-422x-9-80
Abstract: A total of 291 pregnant women over 36?weeks of gestation were enrolled with informed consent. Exfoliative cells were collected from maternal cervix and neonatal buccal mucosa. HPV infection and genotypes were determined with an HPV DNA chip, which can recognise 24 types. The HPV-positive neonates were re-evaluated 6?months after birth to identify the presence of persistent infection. HPV DNA was detected in 18.9?% (55/291) of pregnant women and 3.4?% (10/291) of neonates. Maternal infection was associated with abnormal cytology (p?=?0.007) and primiparity (p?=?0.015). The infected neonates were all born to HPV-positive mothers. The rate of vertical transmission was estimated at 18.2?% (10/55) which was positively correlated with maternal multiple HPV infection (p?=?0.003) and vaginal delivery (p?=?0.050), but not with labour duration and premature rupture of membranes. The rate of concordance of genotype was 100?% in mother-neonate pairs with vertical transmission. The neonatal HPV DNAs found at birth were all cleared at 6?months after delivery.Vertical transmission of HPV DNA from HPV infected mother to the neonate increased when the infant was delivered through an infected cervix. However, the absence of persistent infection in infants at 6?months after delivery may suggest temporary inoculation rather than true vertical infection.
Protein Drug-Loaded Polymeric Nanoparticles  [PDF]
Prasamsha Panta, Da Yeon Kim, Jin Seon Kwon, A Reum Son, Kang Woo Lee, Moon Suk Kim
Journal of Biomedical Science and Engineering (JBiSE) , 2014, DOI: 10.4236/jbise.2014.710082
Abstract: Considerable interest and research have focused on the administration of therapeutic proteins. For delivery of therapeutic proteins, bioavailability and stabilization of protein drugs to maintain therapeutically acceptable levels is an important challenge in clinical trials. To overcome these challenges, polymeric nanoparticles have become one of the best methods for protein delivery. In this review, we summarize the current available polymeric nanoparticles designed for protein delivery, current status, and advantages of protein delivery systems.
Analysis of Context Dependence in Social Interaction Networks of a Massively Multiplayer Online Role-Playing Game
Seokshin Son, Ah Reum Kang, Hyun-chul Kim, Taekyoung Kwon, Juyong Park, Huy Kang Kim
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0033918
Abstract: Rapid advances in modern computing and information technology have enabled millions of people to interact online via various social network and gaming services. The widespread adoption of such online services have made possible analysis of large-scale archival data containing detailed human interactions, presenting a very promising opportunity to understand the rich and complex human behavior. In collaboration with a leading global provider of Massively Multiplayer Online Role-Playing Games (MMORPGs), here we present a network science-based analysis of the interplay between distinct types of user interaction networks in the virtual world. We find that their properties depend critically on the nature of the context-interdependence of the interactions, highlighting the complex and multilayered nature of human interactions, a robust understanding of which we believe may prove instrumental in the designing of more realistic future virtual arenas as well as provide novel insights to the science of collective human behavior.
The Spatial Distribution of Quercus mongolica and Its Association with Other Tree Species in Two Quercus mongolica Stands in Mt. Jiri, Korea
Woongsoon Jang,Pil Sun Park,Ah Reum Han,Kyung Youn Kim
Journal of Ecology and Field Biology , 2010,
Abstract: Stand structure and spatial associations of the dominant tree species in Quercus mongolica stands wereinvestigated to understand interspecific relationships and the persistent dominance of Q. mongolica. We examined thespecies composition, DBH (diameter at breast height) distribution, and spatial distribution of trees (≥ 2.5 cm DBH) in twopermanent 100 m x 100 m plots in Q. mongolica-dominant stands on the western part of Mt. Jiri. Ripley’s K-function wasused to characterize the spatial patterns and associations of dominant tree species. Q. mongolica showed a continuousand reverse-J shaped DBH distribution with clumped spatial distribution in both study sites. Q. mongolica and Abieskoreana exhibited a negative association implying potential interspecific competition. The positive spatial associationbetween Q. mongolica and Alnus hirsuta var. sibirica and Fraxinus sieboldiana were affected by site characteristics: limitedhabitat conditions with a large proportion of rock surface. Our results suggest that interactions among species werecomplex and ranged from positive to negative. Differences in stand and site characteristics and regeneration mechanismsamong the species play an important role in regulating their spatial distribution patterns, while competition betweenindividuals also contributes to spatial patterning of these communities. The high density and the early developmentalstage of spatial distribution and structural characteristics of Q. mongolica and the relatively low importance values ofother species in the stands imply that Q. mongolica will remain dominant in the study sites in the near future.
Acupuncture Enhances the Synaptic Dopamine Availability to Improve Motor Function in a Mouse Model of Parkinson's Disease
Seung-Nam Kim, Ah-Reum Doo, Ji-Yeun Park, Hyungjin Bae, Younbyoung Chae, Insop Shim, Hyangsook Lee, Woongjoon Moon, Hyejung Lee, Hi-Joon Park
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0027566
Abstract: Parkinson's disease (PD) is caused by the selective loss of dopaminergic neurons in the substantia nigra (SN) and the depletion of striatal dopamine (DA). Acupuncture, as an alternative therapy for PD, has beneficial effects in both PD patients and PD animal models, although the underlying mechanisms therein remain uncertain. The present study investigated whether acupuncture treatment affected dopamine neurotransmission in a PD mouse model using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyri?dine(MPTP). We found that acupuncture treatment at acupoint GB34 improved motor function with accompanying dopaminergic neuron protection against MPTP but did not restore striatal dopamine depletion. Instead, acupuncture treatment increased dopamine release that in turn, may lead to the enhancement of dopamine availability in the synaptic cleft. Moreover, acupuncture treatment mitigated MPTP-induced abnormal postsynaptic changes, suggesting that acupuncture treatment may increase postsynaptic dopamine neurotransmission and facilitate the normalization of basal ganglia activity. These results suggest that the acupuncture-induced enhancement of synaptic dopamine availability may play a critical role in motor function improvement against MPTP.
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