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Vitamin C acts indirectly to modulate isotype switching in mouse B cells
Ami Woo,Jin-Hee Kim,Young-Joo Jeong,Hyung Gun Maeng,Yong-Taek Lee,Jae Seung Kang,Wang Jae Lee,Young-il Hwang 대한해부학회 2010 Anatomy & Cell Biology Vol.43 No.1
Vitamin C, one of essential micronutrients, has been reported to modulate the humoral immune responses in some mammals. We investigated whether vitamin C might modulate this response in mice by directly affecting B cells. Splenic B cells were isolated and activated by CD40- and B cell receptor-ligation in vitro. The cells were cultured with a pretreatment of vitamin C from 0 to 1 mM of concentrations. Vitamin C slightly increased apoptosis of B cells dose-dependently and behaved as an antioxidant. We found that in vivo administration of vitamin C by intraperitoneal injection affected isotype switching as previously reported: the titer of antigen-specific IgG1 antibody was decreased, while that of IgG2a was unaffected. Somewhat different from those observed in vivo, in vitro exposure to vitamin C slightly decreased isotype switching to IgG1 and increased isotype switching to IgG2a. Pretreatment with vitamin C in the safe range did not affect either proliferation of cultured B cells or the expression of CD80 and CD86 in those cells. Taken together, in vivo results suggest that vitamin C acts to modulate isotype switching in the mouse. However, because of our in vitro results, we suggest that the modulation exerted by vitamin C in vivo is by indirectly affecting B cells, perhaps by directly influencing other immune cells such as dendritic cells.
The Influence of the Quasi-biennial Oscillation on the Madden-Julian Oscillation: A Short Review
Zane Martin,Seok-Woo Son,Amy Butler,Harry Hendon,Hyemi Kim,Adam Sobel,Shigeo Yoden,Chidong Zhang 한국기상학회 2021 한국기상학회 학술대회 논문집 Vol.2021 No.10
The stratospheric quasi-biennial oscillation (QBO) and the tropospheric Madden-Julian oscillation (MJO) are strongly linked in boreal winter. In this Review, we synthesize observational and modelling evidence for this QBO-MJO connection and discuss its effects on MJO teleconnections and subseasonal-to-seasonal predictions. After 1980, observations indicate that, during winters when lower-stratospheric QBO winds are easterly, the MJO is ∼40% stronger and persists roughly 10 days longer compared with when QBO winds are westerly. Global subseasonal forecast models, in turn, show a one-week improvement (or 25% enhancement) in MJO prediction skill in QBO easterly versus QBO westerly phases. Despite the robustness of the observed QBO-MJO link and its global impacts via atmospheric teleconnections, the mechanisms that drive the connection are uncertain. Theories largely centre on QBO-related temperature stratification effects and subsequent impacts on deep convection, though other hypotheses propose that cloud radiative effects or QBO impacts on wave propagation might be important. Most numerical models, however, are unable to reproduce the observed QBO-MJO relationship, suggesting biases, deficiencies or omission of key physical processes in the models. While future work must strive to better understand all aspects of the QBO-MJO link, focus is needed on establishing a working mechanism and capturing the connection in models.
Martineau, Patrick,Son, Seok-Woo,Taguchi, Masakazu,Butler, Amy H. Copernicus GmbH 2018 Atmospheric Chemistry and Physics Vol.18 No.10
<P>Abstract. The agreement between reanalysis datasets, in terms of the zonal-mean momentum budget, is evaluated during sudden stratospheric warming (SSW) events. It is revealed that there is a good agreement among datasets in the lower stratosphere and troposphere concerning zonal-mean zonal wind, but less so in the upper stratosphere. Forcing terms of the momentum equation are also relatively similar in the lower atmosphere, but their uncertainties are typically larger than uncertainties of the zonal-wind tendency. Similar to zonal-wind tendency, the agreement among forcing terms is degraded in the upper stratosphere. Discrepancies among reanalyses increase during the onset of SSW events, a period characterized by unusually large fluxes of planetary-scale waves from the troposphere to the stratosphere, and decrease substantially after the onset. While the largest uncertainties in the resolved terms of the momentum budget are found in the Coriolis torque, momentum flux convergence also presents a non-negligible spread among the reanalyses. Such a spread is reduced in the latest reanalysis products, decreasing the uncertainty of the momentum budget. It is also found that the uncertainties in the Coriolis torque depend on the strength of SSW events: the SSW events that exhibit the most intense deceleration of zonal-mean zonal wind are subject to larger discrepancies among reanalyses. These uncertainties in stratospheric circulation, however, are not communicated to the troposphere. </P>
Namok Choi,Sarah B. Bush,Hongryun Woo,Amy E. Hunter,Tim S. Truitt 한국상담학회 2021 Journal of Asia Pacific counseling Vol.11 No.2
The purpose of this study was to connect achievement motivational variables delineated in expectancy-value (E-V) theory and the dimensions reflected in the factor structure of the 12 items that measure attitudes toward mathematics included in 2007 TIMSS Eighth Grade Student Questionnaire, in order to suggest ways to use the 12 items in a psychometrically and theoretically sound manner. The sample was drawn from the 2007 national TIMSS database and was split into an exploratory and a validation sample. A three-factor solution with oblique rotation from the exploratory sample was deemed to be the best internal structure for the 12-item scores, which accounted for approximately 65% of the total variance. A confirmatory factor analysis from the validation sample indicated that the fit of the three-factor model to the data was adequate, χ2 (54) = 827.960, p < .01; NFI = .955; CFI = .958; RMSEA = .064. These findings suggest that, with relative confidence, researchers can use the 12 items to generate three mathematics attitude variables that are aligned with E-V theory: mathematics confidence, intrinsic valuing, and extrinsic valuing. Implications for school counselors and educators are addressed.