Antioxidant Activity of Caffeic Acid through a Novel Mechanism under UVA Irradiation

Effect of caffeic acid on the formation of hydroxyl radicals was examined during xanthone-mediated photosensitization. The reaction was performed on irradiation (λ = 365 nm) of the standard reaction mixture containing 15 µM xanthone, 0.1 M 5,5-dimethyl-1-pyrroline N-oxide (DMPO) and 20 mM phosphate buffer (pH 7.4) using electron paramagnetic resonance (EPR) with spin trapping. Caffeic acid inhibited the formation of hydroxyl radicals. Caffeic acid hardly scavenged both hydroxyl radicals and superoxide radicals under conditions employed in this paper in spite of its ability to act as a hydrogen donor or a reagent for the aromatic hydroxylation, because high concentration of DMPO trapped hydroxyl radicals overwhelmingly. Furthermore, caffeic acid inhibited the formation of hydroxyl radicals in the standard reaction mixture with EDTA under UVA irradiation. Accordingly, the inhibitory effect of caffeic acid on the formation of hydroxyl radicals in the standard reaction mixture under UVA irradiation is not due to its ability to chelate iron. Thus, the inhibitory effect of caffeic acid seems to occur in the standard reaction mixture under UVA irradiation through a novel antioxidation activity, i.e., ability to quench the exited xanthone

Formation of 7-carboxyheptyl radical induced by singlet oxygen in the reaction mixture of oleic acid, riboflavin and ferrous ion under the UVA irradiation

Identification of the radicals was performed for the standard reaction mixtures, which contained 4.3 mM oleic acid, 25 µM riboflavin, 1 mM FeSO4(NH4)2SO4, 10 mM cholic acid, 40 mM phosphate buffer (pH 7.4) and 0.1 M α-(4-pyridyl-1-oxide)-N-tert-butylnitrone under the UVA irradiation (365 nm), using an electron spin resonance, an high performance liquid chromatography-electron spin resonance and an high performance liquid chromatography-electron spin resonance-mass spectrometry. The electron spin resonance and high performance liquid chromatography-electron spin resonance measurements of the standard reaction mixtures showed prominent signals (αN = 1.58 mT and αHβ = 0.26 mT) and peaks 1 and 3 (retention times, 37.0 min and 49.0 min). Since the peak 3 was not observed for the standard reaction mixture without oleic acid, the radical of the peak 3 seems to be derived from oleic acid. Singlet oxygens seem to participate in the formation of the oleic acid-derived radicals because the peak height of the peak 3 observed in the standard reaction mixture of D2O increased to 308 ± 72% of the control. The high performance liquid chromatography-electron spin resonance-mass spectrometry analysis showed that 7-carboxyheptyl radical forms in the standard reaction mixture

The polysemy of the Chinese verb “Ti(替)”

内田慶市教授 井上泰山教授 退休記念

リウマチ因子陽性ヒト血清中の免疫グロブリンGクラスリウマチ因子と免疫複合体ならびにCRPとの相関性

We measured the concentration of three immunoglobulin classes of rheumatoid factors (Ig-RFs), C3d binding IgG immune complex (C3d-IC), C1q binding IgG immune complex (C1q-IC) and C-reactive protein (CRP) in 74 samples of human sera with high levels of RF (24.0~2350.0IU/ml). In sera with high levels of C3d-IC (>15.0μg/ml), there was a positive correlation between the levels of CRP and the IgG-RF, but there was no correlation between the levels of CRP and the immune complexes (C3d-IC and C1q-IC). And then, there was a positive correlation between the levels of CRP and IgG-RF or C3d-IC and IgG-RF when the levels of C1q-IC in patients sera were higher than 80.0μg/ml. However, there was no correlation between the levels of CRP and C1q-IC in these patients sera containing high levels of both C3d-IC and C1q-IC. These results indicated that the determination of C3d-IC, C1q-IC, IgG-RF and CRP in human sera containing RF denote different implications as inflammatory indexes on progression of rheumatoid arthritis and other autoimmune diseases.一般に慢性関節リウマチの診断ならびに活動性の一指標として、日常臨床検査では患者血清中のリウマチ因子の測定が実施されている。本論文ではRF検査依頼が有り、高RF値（24.0～2350.0IU/ml）を示した患者血清74検体について、免疫グロブリンクラス別RF値を測定するとともに自己IgGと補体との免疫複合体（IC）であるC1q-IgG・IC（C1q-IC）、C3d-IgG・IC（C3d-IC）ならびにCRP値を測定し、それらの測定値間の相関性について統計学的検討を行った。C3d-IC値が15.0μg/ml以上の高値を示す患者血清では、CRP値とIgGクラスのRF（IgG-RF）値間については正の相関結果がが得られた。また、C1q-IC値が80.0μg/ml以上の場合にもCRP値とIgG-RF値間およびC3d-IC値とIgG-RF値間では正の相関結果が得られた。しかし、C3d-ICならびにC1q-ICともに高値例の患者血清中のCRP値とC1q-IC値間には有意な相関は観察されなかった。以上の結果より、慢性関節リウマチの活動度を判定する上で、従来から炎症マーカーとしてCRP値が利用されているが、血清中に免疫複合体が高レベルに検出される患者については、炎症の指標としてCRP以外にもC1q-ICやC3d-ICおよびIgG-RF等を加えた総合的な判断が必要であることが示唆される

Possible Charge-Exchange X-Ray Emission in the Cygnus Loop Detected with Suzaku

X-ray spectroscopic measurements of the Cygnus Loop supernova remnant indicate that metal abundances throughout most of the remnant's rim are depleted to about 0.2 times the solar value. However, recent X-ray studies have revealed in some narrow regions along the outermost rim anomalously "enhanced" abundances (up to about 1 solar). The reason for these anomalous abundances is not understood. Here, we examine X-ray spectra in annular sectors covering nearly the entire rim of the Cygnus Loop using Suzaku (21 pointings) and XMM-Newton (1 pointing). We find that spectra in the "enhanced" abundance regions commonly show a strong emission feature at about 0.7 keV. This feature is likely a complex of He-like O K(gamma + delta + epsilon), although other possibilities cannot be fully excluded. The intensity of this emission relative to He-like O Kalpha appears to be too high to be explained as thermal emission. This fact, as well as the spatial concentration of the anomalous abundances in the outermost rim, leads us to propose an origin from charge-exchange processes between neutrals and H-like O. We show that the presence of charge-exchange emission could lead to the inference of apparently "enhanced" metal abundances using pure thermal emission models. Accounting for charge-exchange emission, the actual abundances could be uniformly low throughout the rim. The overall abundance depletion remains an open question.Comment: Published in Ap

Variable Selection in Nonlinear Principal Component Analysis

Principal components analysis (PCA) is a popular dimension reduction method and is applied to analyze quantitative data. For PCA to qualitative data, nonlinear PCA can be applied, where the data are quantified by using optimal scaling that nonlinearly transforms qualitative data into quantitative data. Then nonlinear PCA reveals nonlinear relationships among variables with different measurement levels. Using this quantification, we can consider variable selection in the context of PCA for qualitative data. In PCA for quantitative data, modified PCA (M.PCA) of Tanaka and Mori derives principal components which are computed as a linear combination of a subset of variables but can reproduce all the variables very well. This means that M.PCA can select a reasonable subset of variables with different measurement levels if it is extended so as to deal with qualitative data by using the idea of nonlinear PCA. A nonlinear M.PCA is therefore proposed for variable selection in nonlinear PCA. The method, in this chapter, is based on the idea in “Nonlinear Principal Component Analysis and its Applications” by Mori et al. (Springer). The performance of the method is evaluated in a numerical example

Development of Calorie Restriction Mimetics as Therapeutics for Obesity, Diabetes, Inflammatory and Neurodegenerative Diseases

Calorie restriction (CR) is the most robust intervention that decreases morbidity and mortality, and thereby increases the lifespan of many organisms. Although the signaling pathways involved in the beneficial effects of CR are not yet fully understood. Several candidate pathways and key molecules have been identified. The effects of CR are highly conserved from lower organisms such as yeast to higher mammals such as rodents and monkeys. Recent studies have also demonstrated beneficial effects of CR in humans, although we need much longer studies to evaluate whether CR also increases the lifespan of humans. In reality, it is difficult for us to conduct CR interventions in humans because the subjects must be kept in a state of hunger and the duration of this state needed to achieve a clinically meaningful effect is still unknown. Thus, research in this field is focusing on the development of molecules that mimic the beneficial effects of CR without reducing food intake. Some of these candidate molecules include plant-derived functional chemicals (phyto-chemicals), synthetic small molecules, and endocrine molecules such as adipokines. Several studies have already shown that this research field may yield novel drugs for the treatment of age-related diseases such as diabetes. In this article, we describe the target pathways, candidate molecules, and strategies to develop CR mimetics