Showing papers by "Kangwon National University published in 2006"

The Gravity Equation in International Trade in Services

Abstract: The main purpose of this paper is to assess the impact of various factors on bilateral services trade, relative to that on bilateral goods trade. To accomplish this purpose, using the standard gravity model, we ran regressions on bilateral services trade and goods trade between 10 OECD member countries and other economies (including OECD member and nonmember countries) for the years 1999 and 2000. One main and interesting result is that services trade is better predicted by gravity equations than goods trade. Another interesting result is that there is a complementary relationship between goods exports and services imports.

Fractalkine stimulates angiogenesis by activating the Raf-1/MEK/ERK- and PI3K/Akt/eNOS-dependent signal pathways.

Abstract: Fractalkine (FKN) has been implicated in modulation of angiogenesis and vascular inflammation, but the underlying mechanism has not been elucidated. We have investigated the molecular mechanism by which FKN regulates angiogenesis. We found that recombinant FKN increases in vitro proliferation, migration, and tube formation of human umbilical vein endothelial cells and stimulates in vivo angiogenesis. FKN-induced angiogenesis was accompanied by phosphorylation of ERK, Akt, and endothelial nitric oxide (NO) synthase (eNOS), as well as an increase in NO production. These biochemical events and angiogenesis were completely inhibited by the G protein-coupled receptor inhibitor pertussis toxin. Inhibitors of Raf-1, MEK, phosphatidylinositol 3-kinase (PI3K), and eNOS or transfection with dominant-negative forms of ERK and Akt significantly suppressed the angiogenic activity of FKN. However, inhibitors of Raf-1 and MEK or a dominant-negative ERK mutant blocked FKN-induced ERK, but not Akt and eNOS, phosphorylation. The PI3K inhibitor and a dominant-negative mutant of Akt suppressed Akt and eNOS phosphorylation and NO production. Our results demonstrated that FKN stimulated angiogenesis by activating the Raf-1/MEK/ERK and PI3K/Akt/eNOS/NO signal pathways via the G protein-coupled receptor CX3CR1, indicating that two pathways are required for full angiogenic activity of FKN. This study suggests that FKN may play an important role in the pathophysiological process of inflammatory angiogenesis.

Serum cholesterol, haemorrhagic stroke, ischaemic stroke, and myocardial infarction: Korean national health system prospective cohort study

Abstract: Objective To investigate risk factors, such as heavy alcohol consumption, that might explain any increased risk of haemorrhagic stroke associated with low blood cholesterol. Design Prospective cohort study. Setting Korea. Participants 787 442 civil servants (661 700 men, 125 742 women) aged 30-64. Main outcome measures Cardiovascular risk factors were assessed at biennial health check. Data on morbidity and mortality were ascertained from 1990 to 2001 using hospital admissions and mortality surveillance systems. Results 6328 cases of ischaemic stroke (6021 men, 307 women), 3947 cases of haemorrhagic stroke (3748 men, 199 women), 3170 cases of undefined stroke (2902 men, 268 women), and 4417 cases of myocardial infarction (4305 men, 112 women) occurred. Ischaemic stroke and myocardial infarction were strongly and positively associated with blood cholesterol (hazard ratio per 1 mmol/l cholesterol 1.20 (95% confidence 1.16 to 1.24) and 1.48 (1.43 to 1.53), respectively). Haemorrhagic stroke showed an inverse association in fully adjusted models (0.91, 0.87 to 0.95). This inverse association was confined to participants with hypertension. When stratified by concentration of γ glutamyl transferase (GGT), an indicator of alcohol consumption, the association was not seen in participants with low concentrations of GGT, and it was independent of hypertension in those with high concentrations of GGT (> 80 U/l).

Expression and RNA interference-induced silencing of the dammarenediol synthase gene in Panax ginseng.

Abstract: Panax ginseng is one of the most highly valued herbal medicines in the Orient, where it has gained an almost magical reputation for being able to maintain the quality of life. The root of ginseng contains noble tetracyclic triterpenenoid saponins (ginsenosides), which are thought to be the major effective ingredients in P. ginseng. The first committed step in ginsenoside synthesis is the cyclization of 2,3-oxidosqualene to dammarenediol II by oxidosqualene cyclase, dammarenediol synthase (DDS). The gene encoding DDS has been characterized. Here, we investigated the expression of the DDS gene together with the genes involved in ginsenoside biosynthesis (SS, SE, PNX, PNY, PNY2 and PNZ). Expression of DDS mRNA was higher in flower buds compared with root, leaf and petiole of ginseng plants. Elicitor (methyl jasmonate) treatment up-regulated the expression of DDS mRNA. Ectopic expression of DDS in a yeast mutant (erg7) lacking lanosterol synthase resulted in the production of dammarenediol and hydroxydammarenone which were confirmed by liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (LC/ APCIMS). RNA interference (RNAi) of DDS in transgenic P. ginseng resulted in silencing of DDS expression which leads to a reduction of ginsenoside production to 84.5% in roots. These results indicate that expression of DDS played a vital role in the biosynthesis of ginsenosides in P. ginseng.

Prognostic factors in neocortical epilepsy surgery: multivariate analysis.

Abstract: Summary: Purpose: Defining prognostic factors for neocortical epilepsy surgery is important for the identification of ideal candidates and for predicting the prognosis of individual patients. We use multivariate analysis to identify favorable prognostic factors for neocortical epilepsy surgery. Methods: One hundred ninety-three neocortical epilepsy patients, including 91 without focal lesions on MRI, were included. Sixty-one had frontal lobe epilepsy (FLE), 80 had neocortical temporal lobe epilepsy (nTLE), 21 had parietal lobe epilepsy (PLE), and 22 had occipital lobe epilepsy (OLE). The primary outcome variable was patient status ≥2 years after surgery (i.e., seizure free or not). Clinical characteristics and the recent presurgical diagnostic modalities were considered as probable prognostic factors. Univariate and standard multiple logistic regression analyses were used to identify favorable prognostic factors. Results: The seizure-free rate was 57.5%. By univariate analysis, a focal lesion on MRI, localized ictal onset on surface EEG, epilepsies other than FLE, localized hypometabolism on fluorodeoxyglucose–positron emission tomography (FDG-PET), and pathologies other than cortical dysplasia were significantly associated with a seizure-free outcome (p < 0.05). Multivariate analysis revealed that a focal lesion on MRI (p = 0.003), correct localization by FDG-PET (p = 0.007), and localized ictal onset on EEG (p = 0.01) were independent predictors of a good outcome. Conclusions: The presence of a focal lesion on MRI, correct localized hypometabolism on FDG-PET, or localized ictal rhythms on EEG were identified as predictors of a seizure-free outcome. Our results suggest that these findings allow the selection of better candidates for neocortical epilepsy surgery.

Molecular cloning and expression of genes encoding a novel dioxygenase involved in low- and high-molecular-weight polycyclic aromatic hydrocarbon degradation in Mycobacterium vanbaalenii PYR-1.

Abstract: Mycobacterium vanbaalenii PYR-1 is able to metabolize a wide range of low- and high-molecular-weight (HMW) polycyclic aromatic hydrocarbons (PAHs). A 20-kDa protein was upregulated in PAH-metabolizing M. vanbaalenii PYR-1 cells compared to control cultures. The differentially expressed protein was identified as a β subunit of the terminal dioxygenase using mass spectrometry. PCR with degenerate primers designed based on de novo sequenced peptides and a series of plaque hybridizations were done to screen the M. vanbaalenii PYR-1 genomic library. The genes, designated nidA3B3, encoding the α and β subunits of terminal dioxygenase, were subsequently cloned and sequenced. The deduced enzyme revealed close similarities to the corresponding PAH ring-hydroxylating dioxygenases from Mycobacterium and Rhodococcus spp. but had the highest similarity, 61.9%, to the α subunit from Nocardioides sp. strain KP7. The α subunit also showed 52% sequence homology with the previously reported NidA from M. vanbaalenii PYR-1. The genes nidA3B3 were subcloned into the expression vector pET-17b, and the enzyme activity in Escherichia coli cells was reconstituted through coexpression with the ferredoxin (PhdC) and ferredoxin reductase (PhdD) genes of the phenanthrene dioxygenase from Nocardioides sp. strain KP7. The recombinant PAH dioxygenase appeared to favor the HMW PAH substrates fluoranthene, pyrene, and phenanthrene. Several other PAHs, including naphthalene, anthracene, and benz[a]anthracene, were also converted to their corresponding cis-dihydrodiols. The recombinant E. coli, however, did not show any dioxygenation activity for phthalate and biphenyl. The upregulation of nidA3B3 in M. vanbaalenii PYR-1 induced by PAHs was confirmed by reverse transcription-PCR analysis.

Effects of supplementation of β-glucans on growth performance, nutrient digestibility, and immunity in weanling pigs

Abstract: Two experiments were conducted to evaluate the efficacy of beta-glucan on growth performance, nutrient digestibility, and immunity in weanling pigs. In Exp. 1, 210 weanling pigs (6.38 +/- 0.92 kg of BW) were fed dietary beta-glucan (0, 0.01, 0.02, 0.03, or 0.04%) for 5 wk. In Exp. 2, 168 pigs (6.18 +/- 1.31 kg of BW) were fed no beta-glucan or antibiotics (T1), 0.02% beta-glucan (T2), only antibiotics (T3), or 0.02% beta-glucan with antibiotics (T4) for 8 wk. In Exp. 2, the antibiotics fed were apramycin and carbadox in phase I (0 to 2 wk) and carbadox and chlortetracycline in phase II (3 to 8 wk). During Exp. 2, the performance study was conducted for 5 wk, and the immune response was tested until 8 wk. In Exp. 1, there was a trend for a linear increase (P = 0.068) in ADG as the dietary beta-glucan concentration increased in the diet. The digestibilities of DM, GE, CP, ether extract, Ca, and P increased linearly (P < 0.05) in the beta-glucan-supplemented pigs. In Exp. 2, the overall ADG was greater (P < 0.05) in treatment T4 compared with the control group (T1). Also, except for P, this group showed greater (P < 0.05) nutrient digestibilities than the control group. In Exp. 2, at d 15, 24, and 46 antibody titers were measured by ELISA against Pasteurella multocida type A and D after vaccination with atrophic rhinitis, and they differed significantly (P < 0.05) with no particular trend. Flow cytometry was used to determine porcine lymphocyte subpopulations at 4 and 8 wk of Exp. 2. There was an increase in CD4 cells (P < 0.05) and a trend for an increase in CD8 cells (P < 0.10) at 8 wk in pigs fed the T2 diet compared with the other groups. Overall, increasing the dietary concentrations of beta-glucan did not improve ADG without antibiotic, and in weanling pigs antibiotics seem to be more effective in improving nutrient digestibilities and growth performance than beta-glucan.

Healthy Twin: a twin-family study of Korea--protocols and current status.

Abstract: "Healthy Twin" is a twin family study extension of the existing Korean Twin-Family Register. Healthy Twin recruits adult like-sex twins over the age of 30 and their adult family members. Healthy Twin protocols are primarily tailored to the study of the quantitative trait loci of complex traits as well as to the role of environment in the etiology of complex diseases. A full-length survey is underway, including questionnaires, health examinations and the collection of biological specimens. So far, 820 individuals (169 twin pairs and their families) have participated in the survey and 1068 individual twins (608 twin pairs) have replied to the mailed zygosity questionnaire as of July 2006. The first phase (2005-2006) of Healthy Twin will recruit 1550 individuals (including about 380 twin pairs), and the second phase a proposed 1500 to 2500 additional participants. We report study protocols and zygosity and the distribution of family size of the study participants.

Inflammation, mineral metabolism and progressive coronary artery calcification in patients on haemodialysis

Abstract: Background. Coronary artery calcification (CAC) is an extensive and common complication in patients with end-stage renal disease (ESRD). The aim of this study was to assess prospectively the change in CAC over a 2-year period and to identify the factors that may be associated with CAC progression in ESRD patients. Methods. The final analysis was performed on 40 of 43 stable haemodialysis patients who initially entered into the study. The study population underwent multirow spiral computed tomography to derive CAC scores at baseline and after a minimum of 12 months (24 months in 30 patients, 18 months in four, and 12 months in the remaining six patients). To provide a stable estimate that was unbiased with respect to the baseline CAC, square root-transformed CAC scores were used for the analyses of the changes in CAC. Results. The median CAC score was 191 (range, 0–2403) mm 3 at baseline and increased to 253 (range, 0–2745) mm 3 at follow-up (P<0.001) and the median annualized change in square root-transformed CAC score was 1.48 (range, � 0.95–8.64) mm 3 /year. The annualized change of the square root-transformed CAC score positively correlated with the timeintegrated levels of C-reactive protein (R ¼ 0.521, P ¼ 0.001), phosphorus (R ¼ 0.433, P ¼ 0.005) and

Inhibition of matrix metalloproteinase-9 prevents neutrophilic inflammation in ventilator-induced lung injury.

Abstract: Neutrophils are considered to play a central role in ventilator-induced lung injury (VILI). However, the pulmonary consequences of neutrophil accumulation have not been fully elucidated. Matrix met...

Pathological dynamics of activated microglia following medial forebrain bundle transection

Abstract: To elucidate the role and pathological dynamics of activated microglia, this study assessed the phagocytic, immunophenotypic, morphological, and migratory properties of activated microglia in the medial forebrain bundle (MFB) axotomized rat brain. Activated microglia were identified using two different monoclonal antibodies: ED1 for phagocytic activity and OX6 for major histocompatibility complex (MHC) class II. Phagocytic microglia, characterized by ED1-immunoreactivity or ED1- and OX6-immunoreactivity, appeared in the MFB and substantia nigra (SN) as early as 1-3 days post-lesion (dpl), when there was no apparent loss of SN dopamine (DA) neurons. Thereafter, a great number of activated microglia selectively adhered to degenerating axons, dendrites and DA neuronal somas of the SN. This was followed by significant loss of these fibers and nigral DA neurons. Activation of microglia into phagocytic stage was most pronounced between 14 approximately 28 dpl and gradually subsided, but phagocytic microglia persisted until 70 dpl, the last time point examined. ED1 expression preceded MHC II expression in phagocytic microglia. All phagocytic microglia sticking to DA neurons showed activated but ramified form with enlarged somas and thickened processes. They were recruited to the SNc from cranial, dorsal and ventral aspects along various structures and finally stuck to DA neurons of the SNc. Characteristic rod-shaped microglia in the white matter were thought to migrate a long distance. The present study strongly suggests that neurons undergoing delayed neurodegeneration may be phagocytosed by numerous phagocytic, ramified microglia at various sites where specific surface signals are exposed or diffusible molecules are released.

Surgically treated tuberculum sellae and diaphragm sellae meningiomas: the importance of short-term visual outcome.

Abstract: OBJECTIVE: The visual outcome in patients with tuberculum and diaphragm sellae meningiomas treated with microsurgery was evaluated. Prognostic and diagnostic values of short- and long-term postoperative visual outcome and etiology for postoperative visual deterioration are discussed with special attention. METHODS: Clinical data for 30 surgically treated patients with tuberculum and diaphragm sellae meningiomas were reviewed retrospectively. The mean duration of the follow-up period was 75.9 months (range, 12-151 mo). Mean tumor diameter and volume was 25.9 mm (range, 16.3-63.3 mm) and 12.4 cm3 (range, 2.3-125.6 cm3). A visual impairment score was used to assess the short-term (≤2 wk after surgery) and the long-term (>6 mo after surgery) postoperative visual outcome. Various predictive factors for visual outcome were tested statistically. RESULTS: Complete resection was achieved in 23 out of 30 (76.7%) patients. Average preoperative, short- and long-term visual impairment scores were 48.2, 43.4, and 40.9, respectively. Favorable visual outcome was achieved in 80% of patients in the short term and 70% in the long term. Short-term postoperative aggravation of visual function was an ominous sign of further aggravation or at least of little hope for recovery, whereas there was a tendency to improve in the long term if short-term postoperative visual function showed favorable outcome. Recurrence or regrowth of tumor fully was responsible for late deterioration of visual function. No significant prognostic factor for visual outcome could be found. CONCLUSION: Short-term postoperative visual outcome was a strong indicator of permanent visual outcome after surgery for tuberculum sellae and diaphragm sellae meningiomas.

Sustained activation of Akt by melatonin contributes to the protection against kainic acid‐induced neuronal death in hippocampus

Abstract: In the present study, the underlying protective mechanism of melatonin on kainic acid (KA)-induced excitotoxicity was examined in the hippocampus of mice. KA, administered intracerebroventricularly (i.c.v.), induced marked neuronal cell death with concurrent microglial activation and subsequent induction of inducible nitric oxide synthase (iNOS) in the hippocampus. Histopathological analysis demonstrated that melatonin (10 mg/kg), administered 1 hr prior to KA, attenuated KA-induced death of pyramidal neurons in the CA3 region. Melatonin obviously suppressed KA-induced microglial activation and consequent iNOS expression that were determined by increased immunoreactivities of microglial marker OX-6 and iNOS, respectively. Increased phosphorylation of Akt in pyramidal neurons was observed as early as 2 hr after administration of melatonin. Further, melatonin resulted in increased expression of astroglial glial cell line-derived neurotrophic factor (GDNF), which started to appear approximately 6 hr after administration of melatonin. The results of the present study demonstrate that melatonin exerts its neuroprotective action against KA-induced excitotoxicity both through the activation of neuronal Akt and via the direct action on hippocampal neurons and through the increased expression of astroglial GDNF, which subsequently activates neuronal PI3K/Akt pathway. Therefore, the present study suggests that melatonin, pineal secretory product, is potentially useful in the treatment of acute brain pathologies associated with excitotoxic neuronal damage such as epilepsy, stroke, and traumatic brain injury.

Effects of a Novel Cognitive Enhancer, Spiro[imidazo-[1,2-a]pyridine-3,2-indan]-2(3H)-one (ZSET1446), on Learning Impairments Induced by Amyloid-β1–40 in the Rat

Abstract: We have previously shown that intracerebroventricular (icv) infusion of amyloid-beta (Abeta)1-40 produces oxidative stress and cholinergic dysfunction, as well as learning and memory deficits, in rats In the present study, effects of a newly synthesized azaindolizinone derivative, spiro[imidazo[1,2-a]pyridine-3,2-indan]-2(3H)-one (ZSET1446), were assessed in rats with learning deficits induced by Abeta1-40 or scopolamine The icv infusion of Abeta1-40 caused impairments in spontaneous alternation behavior in a Y-maze task, spatial reference and short-term memory in a water-maze task, and retention of passive-avoidance learning Abeta1-40-infused rats also showed reduction in choline acetyltransferase (ChAT) activity in the medial septum and hippocampus, but not in the basal forebrain and cortex, and a decrease in glutathione S-transferase (GST)-like immunoreactivity in the cortex Nicotine-stimulated acetylcholine (ACh) release in Abeta1-40-infused rats was lower than that in vehicle-infused rats Oral administration of ZSET1446 at the dose range of 001 to 1 mg/kg ameliorated Abeta1-40-induced learning impairment in Y-maze, water-maze, and passive-avoidance tasks ZSET1446 reversed the decrease of ChAT activity in the medial septum and hippocampus, GST-like immunoreactivity in the cortex, and nicotine-stimulated ACh release of Abeta1-40-treated rats to the levels of vehicle-infused control rats Furthermore, 0001 to 01 mg/kg ZSET1446 showed ameliorative effects on learning impairments caused by scopolamine in a passive-avoidance task These results suggest that ZSET1446 may be a potential candidate for development as a therapeutic agent to manage cognitive impairment associated with conditions such as Alzheimer's disease

In situ generation of vinyl allenes and its applications to one-pot assembly of cyclohexene, cyclooctadiene, 3,7-nonadienone, and bicyclo[6.4.0]dodecene derivatives with palladium-catalyzed multicomponent reactions.

Abstract: A novel tandem Pd-catalyzed cross-coupling and [4 + 4] cycloaddition sequence allows the rapid synthesis of eight-membered carbocycles starting from α-bromovinyl arenes and propargyl bromides in one reaction vessel. It is noteworthy that four components are assembled into one molecule via this procedure. In contrast to α-bromovinyl arenes, α-bromovinyl alkanes afforded tandem cross-coupling and homo [4 + 2] cycloaddition products. Subjecting an equimolar mixture of α-bromostyrene and 2-bromo-1-octene to propargyl bromides furnished the tandem Pd-catalyzed cross-coupling and hetero [4 + 2] cycloaddition product. Exposure of equimolar mixtures of α-bromovinyl arenes to allenylindium resulted in tandem a Pd-catalyzed cross-coupling and hetero [4 + 4] cycloaddition products. Synthesis of vinylallene from the reaction of vinyl triflate with allenylindium followed by Pd-catalyzed carbon monoxide insertion reaction gave the corresponding 3,7-nonadienone product via tandem Pd-catalyzed cross-coupling and [4 + 4 +...

A normative study of the Trail Making Test in Korean elders.

Abstract: Objective The purpose of this study was to explore the effects of age, education and gender on the performance of the Trail Making Test (TMT) and provide normative information in Korean elders. Methods The TMT was administered to 997 community-dwelling volunteers aged 60–90. People with serious neurological, medical and psychiatric disorders, including dementia, were excluded. Results Education and age had significant effects on both parts of the TMT. Gender also had an effect on part A of the TMT (Trail A). Based on these results, the norms of Trail A stratified by age (four overlapping tables), education (four strata) and gender, and the norms of part B of TMT (Trail B) stratified by age (four overlapping tables) and education (three strata). Conclusions Age and educational level had a considerable influence on both Trail A and B. Our normative information on the Trail A will be useful in the elders with poor educational attainment and can be utilized for cross-cultural comparison of the Trail A performance. The fact that a large number of elders fail to complete Trail B indicates a limited applicability of Trail B in elderly population, particularly with poor educational background. Copyright © 2006 John Wiley & Sons, Ltd.

Chemical constituents of the root of Dystaenia takeshimana and their anti-inflammatory activity.

Abstract: In our ongoing search for bioactive compounds originating from the endemic species in Korea, we found that the hexane and EtOAc fractions of the MeOH extract from the root of Dystaenia takeshimana (Nakai) Kitagawa (Umbelliferae) showed cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX) dual inhibitory activity by assessing their effects on the production of prostaglandin D2 (PGD2) and leukotriene C4 (LTC4) in mouse bone marrow-derived mast cells. By activity-guided fractionation, five coumarins, viz. psoralen (2), xanthotoxin (3), scopoletin (4), umbelliferone (5), and (+)-marmesin (6), together with beta-sitosterol (1), were isolated from the hexane fraction, and two phenethyl alcohol derivatives, viz. 2-methoxy-2-(4'-hydroxyphenyl)ethanol (7) and 2-hydroxy-2-(4'-hydroxyphenyl)ethanol (8), three flavonoids, viz. apigenin (9), luteolin (10), and cynaroside (11), as well as daucosterol (12) were isolated from the EtOAc fraction using silica gel column chromatography. In addition, D-mannitol (13) was isolated from the BuOH fraction by recrystallization. Two of the coumarins, scopoletin (4) and (+)-marmesin (6), the two phenethyl alcohol derivatives (7, 8) and the three flavonoids (9-11) were isolated for the first time from this plant. Among the compounds isolated from this plant, the five coumarins as well as the three flavonoids showed COX-2/5-LOX dual inhibitory activity. These results suggest that the anti-inflammatory activity of D. takeshimana might in part occur via the inhibition of the generation of eicosanoids.