Tohoku University · Medicine
Professor Keiko Murakami's research lab focuses on the intersection of environmental toxicology, cellular redox biology, and public health, with a particular emphasis on the impact of trace metals like aluminum on mitochondrial function and oxidative stress. The lab investigates the molecular mechanisms of enzyme inactivation under oxidative conditions, such as aconitase in yeast, and explores the biological activities of microbial enzymes—like nattokinase from *Bacillus subtilis*—in relation to human health. Additionally, the lab conducts population-based epidemiological studies on health behavior inequalities, particularly regarding dental care utilization and obesity, highlighting social determinants such as education and income. These diverse yet interconnected research directions reflect a commitment to understanding how biological, environmental, and socioeconomic factors jointly influence chronic disease risk and health disparities.
Figures are computed from collected data and may differ slightly.
These findings indicate that education and income are differentially associated with alcohol drinking patterns among community-dwelling Japanese men.
Effect of aluminum on the NADPH supply and glutathione regeneration in mitochondria was analyzed. Reduced glutathione acted as a principal scavenger of reactive oxygen species in mitochondria. Aluminum inhibited the regeneration of glutathione from the oxidized form, and the effect was due to the inhibition of NADP-isocitrate dehydrogenase the only enzyme supplying NADPH in mitochondria. In cytosol, aluminum inhibited the glutathione regeneration dependent on NADPH supply by malic enzyme and NAD
Inactivation of aconitase by oxidative stress was analyzed under the in vivo and in situ conditions of yeast cells. Treatment of yeast cells with paraquat caused a specific inactivation of aconitase without affecting the activity of other citric acid cycle enzymes. Addition of copper plus ascorbic acid to permeabilized yeast cells also inactivated aconitase, but did not affect other TCA cycle-related enzymes. Inactivation of aconitase was suggested to be due to the superoxide and hydroxyl radica
Angiotensin I converting enzyme (ACE) was inhibited by the culture medium of Bacillus subtilis subsp. natto, which ferments boiled soy beans to natto, a Japanese traditional food. Subtilisin NAT (nattokinase) produced by B. subtilis also inhibited ACE, and the inhibition was markedly stimulated by heat treatment of subtilisin at 120 °C for 15 min. Inhibition of ACE by subtilisin was of a mixed type: the decrease in V(max) and the increase in K(m) value. SDS-polyacrylamide gel electrophoresis sho
The prevalence of preventive dental care use was lower than that of curative care. The results showed income-related inequality in preventive dental care use among men, though there were no significant income-related gradients of curative dental care use among either men or women. Educational attainment had a positive association with preventive dental care use only among women.
Associations between women's own education and overweight/obesity varied by marital status, and husbands' educational level was important for married women's overweight/obesity. These findings indicate that the social influences bound to educational background affect women's overweight/obesity.
Vitamin B6 deficiency increases the lipid peroxidation and the synthesis of xanthurenic acid from tryptophan. Antioxidant properties of xanthurenic acid were examined in relation to the coordination of transition metals. Xanthurenic acid inhibited the formation of thiobarbituric acid-reactive substances as a marker of iron-mediated lipid peroxidation and copper-dependent oxidation of low density lipoprotein. NADP-isocitrate dehydrogenase (EC 1.1.1.42), a principal NADPH-generating enzyme for the
Those with hypertension had significantly higher stroke risk among old people, while diabetes mellitus was differentially associated with stroke according to age category. Our findings indicate the importance of different prevention strategies for stroke incidence according to age category.
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