日本における鉱物資源の代替供給による経済・環境影響と資源セキュリティ戦略に対する社会的選好評価

京都大学新制・課程博士博士(エネルギー科学)甲第23291号エネ博第416号新制||エネ||79(附属図書館)京都大学大学院エネルギー科学研究科エネルギー社会・環境科学専攻(主査)教授 手塚 哲央, 教授 黒崎 健, 准教授 MCLELLAN Benjamin学位規則第4条第1項該当Doctor of Energy ScienceKyoto UniversityDFA

Multiscale clustering of heavy and light small particles in turbulent channel flow at high Reynolds numbers

To understand the fundamental mechanism of the clustering of heavy and light small particles in high-Reynolds-number wall turbulence, we conduct direct numerical simulations of particle dispersions in turbulent channel flow at the friction Reynolds number Reτ=2000. Heavy and light particles form clusters with different shapes, and the cluster size is larger for particles with longer relaxation time. To reveal the origin of these multiscale clusters of particles, we investigate particle distributions around multiscale vortices. Vortices tend to sweep out heavy particles and tend to attract light ones with a relaxation time comparable with their turnover time. These clustering phenomena due to coherent vortices can occur irrespective of their size, existing height and the friction Reynolds number. We can therefore explain the multiscale nature of particle clustering in terms of the time scale matching between particles and vortices

Induction of Chromatin Damage and Distribution of Isochromatid Breaks in Human Fibroblast Cells Exposed to Heavy Ions

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Association of an overlap syndrome of autoimmune hepatitis and primary biliary cirrhosis with cytomegalovirus infection

A 63-year-old woman, who presented with severe jaundice and elevated serum conjugated bilirubin level, denied alcohol and drug use and showed no evidence of viral hepatitis. Based on clinical and laboratory features, she was diagnosed with autoimmune hepatitis with primary biliary cirrhosis. Hematological and immunochemical assays, radiographic imaging, clinical examination, and liver biopsy were conducted. Laboratory results were the following: negative for fluorescence antinuclear antibody, negative for antismooth muscle antibodies but positive for antinuclear antibody (enzyme-linked immunosorbent assay) and antimitochondrial M2 antibody, high titers of serum globulin, and positive for cytomegalovirus IgM. Liver biopsy showed submassive lobular necrosis, inflammation with broad areas of parenchymal collapse, and chronic nonsuppurative destructive cholangitis. The patient responded well to corticosteroid therapy. This case might illustrate an association between cytomegalovirus infection and the occurrence of autoimmune hepatitis

Paradoxical roles of antioxidant enzymes:Basic mechanisms and health implications

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are generated from aerobic metabolism, as a result of accidental electron leakage as well as regulated enzymatic processes. Because ROS/RNS can induce oxidative injury and act in redox signaling, enzymes metabolizing them will inherently promote either health or disease, depending on the physiological context. It is thus misleading to consider conventionally called antioxidant enzymes to be largely, if not exclusively, health protective. Because such a notion is nonetheless common, we herein attempt to rationalize why this simplistic view should be avoided. First we give an updated summary of physiological phenotypes triggered in mouse models of overexpression or knockout of major antioxidant enzymes. Subsequently, we focus on a series of striking cases that demonstrate “paradoxical” outcomes, i.e., increased fitness upon deletion of antioxidant enzymes or disease triggered by their overexpression. We elaborate mechanisms by which these phenotypes are mediated via chemical, biological, and metabolic interactions of the antioxidant enzymes with their substrates, downstream events, and cellular context. Furthermore, we propose that novel treatments of antioxidant enzyme-related human diseases may be enabled by deliberate targeting of dual roles of the pertaining enzymes. We also discuss the potential of “antioxidant” nutrients and phytochemicals, via regulating the expression or function of antioxidant enzymes, in preventing, treating, or aggravating chronic diseases. We conclude that “paradoxical” roles of antioxidant enzymes in physiology, health, and disease derive from sophisticated molecular mechanisms of redox biology and metabolic homeostasis. Simply viewing antioxidant enzymes as always being beneficial is not only conceptually misleading but also clinically hazardous if such notions underpin medical treatment protocols based on modulation of redox pathways

Prognostic Significance of C-reactive Protein-to-prealbumin Ratio in Patients with Esophageal Cancer

Background: The prognostic value of combination of C-reactive protein and prealbumin (CRP/PAlb) in esophageal cancer remains unclear. Methods: We enrolled 167 esophageal cancer patients who underwent curative esophagectomy. Univariate and multivariate analyses were performed to determine the prognostic significance of various markers, including CRP-to-albumin (CRP/Alb) ratio, modified Glasgow prognostic score, neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and prognostic nutritional index. Results: Receiver operating characteristic analysis revealed the optimal cut-off value of each inflammatory factor, and CRP/PAlb ratio had the greatest discriminative power in predicting recurrence-free survival (RFS) among the examined measures (AUC 0.668). The 5-year overall survival and RFS rates were significantly lower in patients with high CRP/PAlb ratio than in those with low CRP/PAlb ratio (P < 0.001, P = 0.001, respectively). In the univariate analysis, RFS was significantly worse in patients with low BMI, T2 or deeper tumor invasion, positive lymph node metastasis, positive venous invasion, high CRP/PAlb ratio, high CRP/Alb ratio, high NLR, and high LMR. Multivariate analysis revealed that CRP/PAlb, but not CRP/Alb, was an independent prognostic factor along with lymph node metastasis. Conclusion: CRP/PAlb ratio was useful for predicting the prognosis of esophageal cancer patients

Enhanced mitochondrial superoxide scavenging does not Improve muscle insulin action in the high fat-fed mouse

Improving mitochondrial oxidant scavenging may be a viable strategy for the treatment of insulin resistance and diabetes. Mice overexpressing the mitochondrial matrix isoform of superoxide dismutase (sod2(tg) mice) and/or transgenically expressing catalase within the mitochondrial matrix (mcat(tg) mice) have increased scavenging of O2(˙-) and H2O2, respectively. Furthermore, muscle insulin action is partially preserved in high fat (HF)-fed mcat(tg) mice. The goal of the current study was to test the hypothesis that increased O2(˙-) scavenging alone or in combination with increased H2O2 scavenging (mtAO mice) enhances in vivo muscle insulin action in the HF-fed mouse. Insulin action was examined in conscious, unrestrained and unstressed wild type (WT), sod2(tg), mcat(tg) and mtAO mice using hyperinsulinemic-euglycemic clamps (insulin clamps) combined with radioactive glucose tracers following sixteen weeks of normal chow or HF (60% calories from fat) feeding. Glucose infusion rates, whole body glucose disappearance, and muscle glucose uptake during the insulin clamp were similar in chow- and HF-fed WT and sod2(tg) mice. Consistent with our previous work, HF-fed mcat(tg) mice had improved muscle insulin action, however, an additive effect was not seen in mtAO mice. Insulin-stimulated Akt phosphorylation in muscle from clamped mice was consistent with glucose flux measurements. These results demonstrate that increased O2(˙-) scavenging does not improve muscle insulin action in the HF-fed mouse alone or when coupled to increased H2O2 scavenging

Long-term results of a randomized controlled trial comparing neoadjuvant Adriamycin, cisplatin, and 5-fluorouracil vs docetaxel, cisplatin, and 5-fluorouracil followed by surgery for esophageal cancer (OGSG1003)

Sugimura, K, Yamasaki, M, Yasuda, T, et al. Long‐term results of a randomized controlled trial comparing neoadjuvant Adriamycin, cisplatin, and 5‐fluorouracil vs docetaxel, cisplatin, and 5‐fluorouracil followed by surgery for esophageal cancer (OGSG1003). Ann. Gastroenterol. Surg. 2020; 00: 1– 8. https://doi.org/10.1002/ags3.12388

Mitochondrial dysfunction, a probable cause of persistent oxidative stress after exposure to ionizing radiation

Several recent studies have suggested that the reactive oxygen species (ROS) generated from mitochondria contribute to genomic instability after exposure of the cells to ionizing radiation, but the mechanism of this process is not yet fully understood. We examined the hypothesis that irradiation induces mitochondrial dysfunction to cause persistent oxidative stress, which contributes to genomic instability. After the exposure of cells to 5 Gy gamma-ray irradiation, we found that the irradiation induced the following changes in a clear pattern of time courses. First, a robust increase of intracellular ROS levels occurred within minutes, but the intracellular ROS disappeared within 30 min. Then the mitochondrial dysfunction was detected at 12 h after irradiation, as indicated by the decreased activity of NADH dehydrogenase (Complex I), the most important enzyme in regulating the release of ROS from the mitochondrial electron transport chain (ETC). Finally, a significant increase of ROS levels in the mitochondria and the oxidation of mitochondrial DNA were observed in cells at 24 h or later after irradiation. Although further experiments are required, results in this study support the hypothesis that mitochondrial dysfunction causes persistent oxidative stress that may contribute to promote radiation-induced genomic instability