Weak version of restriction estimates for spheres and paraboloids in finite fields

Kang, H.,Koh, D. Academic Press 2014 Journal of mathematical analysis and applications Vol.419 No.2

We study L<SUP>p</SUP>-L<SUP>r</SUP> restriction estimates for algebraic varieties in d-dimensional vector spaces over finite fields. Unlike the Euclidean case, if the dimension d is even, then it is conjectured that the L<SUP>(2d+2)/(d+3)</SUP>-L<SUP>2</SUP> Stein-Tomas restriction result can be improved to the L<SUP>(2d+4)/(d+4)</SUP>-L<SUP>2</SUP> estimate for both spheres and paraboloids in finite fields. In this paper we show that the conjectured L<SUP>p</SUP>-L<SUP>2</SUP> restriction estimate holds in the specific case when test functions under consideration are restricted to d-coordinate functions or homogeneous functions of degree zero. To deduce our result, we use the connection between the restriction phenomena for our varieties in d dimensions and those for homogeneous varieties in (d+1) dimensions.

Potential roles of D-serine and serine racemase in experimental temporal lobe epilepsy

Ryu, H.J.,Kim, J.-E.,Yeo, S.-I.,Kim, D.-S.,Kwon, O.-S.,Choi, S.Y.,Kang, T.-C. Wiley Subscription Services, Inc., A Wiley Company 2010 Journal of neuroscience research Vol.88 No.11

<P>To confirm the roles of D-serinergic gliotransmission in epilepsy, we investigated the relationship between spatiotemporally specific glial responses and the D-serine/serine racemase system in mesial temporal structures following status epilepticus (SE). In control animals, D-serine and serine racemase immunoreactivities were detected mainly in astrocytes. After SE, D-serine and serine racemase immunoreactivities were increased in astrocytes. Double-immunofluorescence study revealed that up-regulation of serine racemase immunoreactivity was relevant not to D-serine immunoreactivity but to nestin or vimentin immunoreactivity. Neither D-serine nor serine racemase was found in naïve or reactive microglia. In addition, phosphorylated N-methyl-D-aspartate (NMDA) receptor subunit 1 (pNR1-Ser896) immunoreactivity in the hippocampus was increased compared with controls. Increased D-serine immunoreactivity showed direct correlation with the phosphorylation of Ser896 of NR1. Given the findings of our previous study, these findings suggest that D-serine and serine racemase in astrocytes may play roles in neuronal hyperexcitability via a cooperative activation of NMDA receptors. Furthermore, serine racemase may be involved in migration and differentiation of immature astrocytes, which is relevant to reactive astrogliosis. © 2010 Wiley-Liss, Inc.</P>

Vitamin D deficiency impairs glucose-stimulated insulin secretion and increases insulin resistance by reducing PPAR-γ expression in nonobese Type 2 diabetic rats

Park, S.,Kim, D.S.,Kang, S. Butterworths ; Elsevier Science Ltd 2016 The Journal of nutritional biochemistry Vol.27 No.-

<P>Human studies have provided relatively strong associations of poor vitamin D status with Type 2 diabetes but do not explain the nature of the association. Here, we explored the physiological pathways that may explain how vitamin D status modulates energy, lipid and glucose metabolisms in nonobese Type 2 diabetic rats. Goto-Kakizaki (GK) rats were fed high-fat diets containing 25 (VD-low), 1000 (VD-normal) or 10,000 (VD-high) cholecalciferol-IU/kg diet for 8 weeks. Energy expenditure, insulin resistance, insulin secretory capacity and lipid metabolism were measured. Serum 25-OH-D levels, an index of vitamin D status, increased dose dependently with dietary vitamin D. VD-low resulted in less fat oxidation without a significant difference in energy expenditure and less lean body mass in the abdomen and legs comparison to the VD-normal group. In comparison to VD-low, VD-normal had lower serum triglycerides and intracellular fat accumulation in the liver and skeletal muscles which was associated with down-regulation of the mRNA expressions of sterol regulatory element binding protein-1c and fatty acid synthase and up-regulation of gene expressions of peroxisome proliferator-activated receptors (PPAR)-alpha and carnitine palmitoyltransferase-1. In euglycemic hyperinsulinemic clamp, whole-body and hepatic insulin resistance was exacerbated in the VD-low group but not in the VD-normal group, possibly through decreasing hepatic insulin signaling and PPAR-gamma expression in the adipocytes. In 3T3-L1 adipocytes 1,25-(OH)(2)-D (10 nM) increased triglyceride accumulation by elevating PPAR-gamma expression and treatment with a PPAR-gamma antagonist blocked the triglyceride deposition induced by 1,25-(OH)2-D treatment. VD-low impaired glucose-stimulated insulin secretion in hyperglycemic clamp and decreased beta-cell mass by decreasing beta-cell proliferation. In conclusion, vitamin D deficiency resulted in the dysregulation of glucose metabolism in GK rats by simultaneously increasing insulin resistance by decreasing adipose PPAR-gamma expression and deteriorating beta-cell function and mass. (C) 2015 Elsevier Inc. All rights reserved.</P>

Implication of intracellular ROS formation, caspase-3 activation and Egr-1 induction in platycodon D-induced apoptosis of U937 human leukemia cells

Shin, D.Y.,Kim, G.Y.,Li, W.,Choi, B.T.,Kim, N.D.,Kang, H.S.,Choi, Y.H. Masson Pub. USA, Inc 2009 BIOMEDICINE AND PHARMACOTHERAPY Vol.63 No.2

Platycodon D is a major constituent of triterpene saponins found in the root of Platycodon grandiflorum, Platycodi Radix, which is widely used in traditional Oriental medicine for the treatment of many chronic inflammatory diseases. The results of previous studies have shown that this compound has in vitro growth-inhibitory activity in human cancer cells, however, the mechanism by which this action occurs is poorly understood. In this study, we examined the effects of platycodon D on the production of reactive oxygen species (ROS) and evaluated the association of these effects with apoptotic tumor cell death using a human leukemic U937 cell line. The results of this study demonstrate that platycodon D mediates ROS production, and that this mediation is followed by a decrease in mitochondrial membrane potential (MMP, ΔΨ<SUB>m</SUB>), activation of caspase-3, and cleavage of poly (ADP-ribose) polymerase (PARP). Both the cytotoxic effects and apoptotic characteristics induced by platycodon D treatment were significantly inhibited by z-DEVD-fmk, a caspase-3 inhibitor, which demonstrates the important role that caspase-3 plays in the observed cytotoxic effect. Additionally, the transcription factor early growth response-1 (Egr-1) gene was transcriptionally activated and the levels of non-steroidal anti-inflammatory drug (NSAID)-activated gene-1 (NAG-1) protein were elevated in platycodon D-treated U937 cells. However, the quenching of ROS generation in response to treatment with a ROS scavenger, N-acetyl-l-cysteine, reversed the platycodon D-induced apoptosis effects via inhibition of Egr-1 activation, ROS production, MMP collapse, and the subsequent activation of caspase-3. Although further studies are needed to demonstrate that increased expression of Egr-1 by platycodon D leads directly to NAG-1 induction and subsequent apoptosis, our observations clearly indicate that ROS induced through Egr-1 activation are involved in the early molecular events involved in the platycodon D-induced apoptotic pathway.

Exendin-4 induction of cyclin D1 expression in INS-1 beta-cells: involvement of cAMP-responsive element.

Kim, M-J,Kang, J-H,Park, Y G,Ryu, G R,Ko, S H,Jeong, I-K,Koh, K-H,Rhie, D-J,Yoon, S H,Hahn, S J,Kim, M-S,Jo, Y-H Journal of Endocrinology, Ltd. [etc.] 2006 The Journal of endocrinology Vol.188 No.3

<P>Glucagon-like peptide-1 (GLP-1) and its analog exendin-4 (EX) have been considered as a growth factor implicated in pancreatic islet mass increase and beta-cell proliferation. This study aimed to investigate the effect of EX on cyclin D1 expression, a key regulator of the cell cycle, in the pancreatic beta-cell line INS-1. We demonstrated that EX significantly increased cyclin D1 mRNA and subsequently its protein levels. Although EX induced phosphorylation of Raf-1 and extracellular-signal-regulated kinase (ERK), both PD98059 and exogenous ERK1 had no effect on the cyclin D1 induction by EX. Instead, the cAMP-elevating agent forskolin induced cyclin D1 expression remarkably and this response was inhibited by pretreatment with H-89, a protein kinase A (PKA) inhibitor. Promoter analyses revealed that the cAMP-responsive element (CRE) site (at position -48; 5'-TAACGTCA-3') of cyclin D1 gene was required for both basal and EX-induced activation of the cyclin D1 promoter, which was confirmed by site-directed mutagenesis study. For EX to activate the cyclin D1 promoter effectively, CRE-binding protein (CREB) should be phosphorylated and bound to the putative CRE site, according to the results of electrophoretic mobility shift and chromatin immunoprecipitation assays. Lastly, a transfection assay employing constitutively active or dominant-negative CREB expression plasmids clearly demonstrated that CREB was largely involved in both basal and EX-induced cyclin D1 promoter activities. Taken together, EX-induced cyclin D1 expression is largely dependent on the cAMP/PKA signaling pathway, and EX increases the level of phosphorylated CREB and more potently trans-activates cyclin D1 gene through binding of the CREB to the putative CRE site, implicating a potential mechanism underlying beta-cell proliferation by EX.</P>

The effect of encapsulant discoloration and delamination on the electrical characteristics of photovoltaic module

Park, N.C.,Jeong, J.S.,Kang, B.J.,Kim, D.H. Pergamon Press 2013 Microelectronics and reliability Vol.53 No.9

Discoloration and delamination (D&D) of encapsulant in a photovoltaic (PV) module affect the electrical characteristics. Therefore, in this study D&D-induced degradations are investigated with a 25-year-old PV module. The average power output of 25-year-old PV modules decreased by 17.9% compared to initial value. However, insulation properties have been stable over 25years. Electroluminescence image shows that discoloration has an effect on the cell degradation. The effect of D&D on the light reflectance and transmittance is evaluated by performing a trapezoidal integration with the standard global reference spectrum. Failure analysis reveals that delamination occurs at the interface between encapsulant and solar cell and also shows that corrosion of solder occurred near delamination site

Influence of water activity on inactivation of Escherichia coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes in peanut butter by microwave heating

Song, W.J.,Kang, D.H. ACADEMIC PRESS LTD 2016 FOOD MICROBIOLOGY Vol.60 No.-

<P>This study evaluated the efficacy of a 915 MHz microwave with 3 different electric power levels to inactivate three pathogens in peanut butter with different a(w). Peanut butter inoculated with Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium and Listeria monocytogenes (0.3, 0.4, and 0.5 a(w)) were treated with a 915 MHz microwave with 2, 4, and 6 kW for up to 5 min. Six kW 915 MHz microwave treatment for 5 min reduced these three pathogens by 1.97 to >5.17 log CFU/g. Four kW 915 MHz microwave processing for 5 min reduced these pathogens by 0.41-1.98 log CFU/g. Two kW microwave heating did not inactivate pathogens in peanut butter. Weibull and Log-Linear + Shoulder models were used to describe the survival curves of three pathogens because they exhibited shouldering behavior. T-d and T-5d values were calculated based on the Weibull and Log-Linear + Shoulder models. T-d values of the three pathogens were similar to D-values of Salmonella subjected to conventional heating at 90 degrees C but T-5d values were much shorter than those of conventional heating at 90 degrees C. Generally, increased a(w) resulted in shorter T-5d values of pathogens, but not shorter T-d values. The results of this study can be used to optimize microwave heating pasteurization system of peanut butter. (C) 2016 Published by Elsevier Ltd.</P>

Valeriana officinalis extract and its main component, valerenic acid, ameliorate d-galactose-induced reductions in memory, cell proliferation, and neuroblast differentiation by reducing corticosterone levels and lipid peroxidation

Nam, S.M.,Choi, J.H.,Yoo, D.Y.,Kim, W.,Jung, H.Y.,Kim, J.W.,Kang, S.Y.,Park, J.,Kim, D.W.,Kim, W.J.,Yoon, Y.S.,Hwang, I.K. Pergamon Press ; Elsevier Science Ltd 2013 Experimental Gerontology Vol.48 No.11

Valeriana officinalis is used in herbal medicine of many cultures as mild sedatives and tranquilizers. In this study, we investigated the effects of extract from valerian root extracts and its major component, valerenic acid on memory function, cell proliferation, neuroblast differentiation, serum corticosterone, and lipid peroxidation in adult and aged mice. For the aging model, d-galactose (100mg/kg) was administered subcutaneously to 6-week-old male mice for 10weeks. At 13weeks of age, valerian root extracts (100mg/kg) or valerenic acid (340μg/kg) was administered orally to control and d-galactose-treated mice for 3weeks. The dosage of valerenic acid (340μg/kg), which is the active ingredient of valerian root extract, was determined by the content of valerenic acid in valerian root extract (3.401+/-0.066mg/g) measured by HPLC. The administration of valerian root extract and valerenic acid significantly improved the preferential exploration of new objects in novel object recognition test and the escape latency, swimming speeds, platform crossings, and spatial preference for the target quadrant in Morris water maze test compared to the d-galactose-treated mice. Cell proliferation and neuroblast differentiation were significantly decreased, while serum corticosterone level and lipid peroxidation in hippocampus were significantly increased in the d-galactose-treated group compared to that in the control group. The administration of valerian root extract significantly ameliorated these changes in the dentate gyrus of both control and d-galactose-treated groups. In addition, valerenic acid also mitigated the d-galactose-induced reduction of these changes. These results indicate that valerian root extract and valerenic acid enhance cognitive function, promote cell proliferation and neuroblast differentiation, and reduce serum corticosterone and lipid peroxidation in aged mice.

Arrangement of Cortical Microtubules in Elongation Epicotyl of Aesculus turbinata Blume

Kang, K.D.,T. Itoh,Soh, W.Y. 全北大學校 基礎科學硏究所 1994 基礎科學 Vol.16 No.-

In order to elucidate the arrangement of microtubules (MTs) during the organ elongation, we examined the arrangements of cortical MTs in the elongating epicotyl of Aesculus turbinata by immunofluorescence microscopy using cryosections. Under both dark and light-dark growth conditions, the arrangement of MTs was associated with the rates of elongation and differed according to the region in the same epicotyl. In the component cells of epicotyl grown in dark, the arrangement of MTs was exclusively transverse in the potential active elongating region (A), relatively transverse in the active clongating region (B) and predominantly oblique in the less-elongating region (C) and in the non-elongating region (D). During the growth of epicotyl, the arrangement of MTs in the component cells was gradually altered from transverse to oblique or longitudinal direction. In light-dark grown epicotyl, the change in MT arrangement of the component cells occurs somewhat earlier than that of dark condition and shows a ratehr gradual process. That is, the arrangement of MTs was predominantly transverse in region A, predominantly oblique in region B. and relatively oblique and/or longitudinal in regions C and D. These results indicate that the change in arrangement of cortical MTs from transverse to oblique or longitudinal ones occurs in the cortex before elongation stops. Orientation of MTs in borth growht conditions seems to be steeper in the outer than in the inner parenchyma cells and to change earlier in the light-dark grown epicotyl.

청소년의 근로 여부에 따른 신체활동 및 스트레스 비교

강지은,김혜원,백다인,신지원,신혜진,심지선,윤도연,이규리,이보라,이혜민,최주연 이화여자대학교 간호과학대학 2014 이화간호학회지 Vol.- No.48

Purpose: The purpose of this study was to investigate the stress and the physical activity according to working in Korean adolescents. Methods: Data were collected from 3 high schools in Seoul and Gyeonggi-do. The total number of four hundred twenty subjects were participated and they completed general questionnaire, International Physical Activity Questionnaire (Korean version) and adolescents stress scale. Data were analyzed by descriptive statistics and t-test using SPSS 21.0 program. Results: The number of employed was 151 (45.2%) and the number of unemployed was 183 (54.8%). Reasons for working were to earn money (44.0%) and to purchase significant product (35.6%). Moderate physical activities of employed students were more than them of unemployed students and there was significant difference (t=3.261, p˂.001). There was no significant difference between employed and unemployed students in the total score of stress. However, there were significant differences on school stress (t=2.854, p=.005) and economical stress (t=3.959, p˂.001) in the subcategory. The stress of employed was higher than the stress of unemployed. Conclusion: As shown in the above result, employed adolescents reported higher levels of both physical activity and stress than unemployed adolescents, thus indicating that employment status of adolescents has a significant impact on physical and mental health. Nursing implications include developing quality care for employed adolescents based on the community health nursing, and providing health education at schools in terms of adolescent employment.