Ryo Kijima

Tohoku University, Japan

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Publications (8)19.16 Total impact

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    ABSTRACT: The influence of 1-deoxynojirimycin (DNJ) derived from mulberry on senescence of endothelial cells was examined with the goal of discovery of a method for prevention of senescence of blood vessels. The effect of DNJ on senescence of human umbilical vein endothelial cells (HUVECs) promoted under high glucose condition was determined. HUVECs were cultured in normal glucose (5.6mmol/L, NG group), normal glucose plus DNJ (10μmol/L, DNJ group), high glucose (30mmol/L, HG group), or high glucose plus DNJ (10μmol/L, HG+DNJ group) and passaged until they reached senescence. The proliferation rate was markedly decreased in the HG group compared with the NG group, and this phenomenon was reversed by DNJ. The frequency of senescent (SA-ß-Gal-positive) cells and the expression level of senescence genes (PAI-1 and p21) were significantly higher in the HG group compared with the NG group, and these changes were blocked by DNJ. Monocyte adhesion, NF-kB activity, and reactive oxygen species production, all of which promote cellular senescence, were significantly increased in the HG group compared with the NG group, and again these changes were blocked by DNJ. Therefore, these results show that DNJ delays cellular senescence that is promoted under high glucose condition.
    Experimental gerontology 04/2014; · 3.34 Impact Factor
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    ABSTRACT: In this study, to study the effect of aging and Apolipoprotein E (ApoE) deficiency on antioxidant ability in mice, we examined whether lipid peroxidation is promoted by aging in ApoE deficient (ApoE(-/-)) mice, which have a shorter lifespan than normal mice. The levels of thiobarbituric acid-reactive substances (TBARS), a biomarker of lipid peroxidation, were measured in plasma and liver in ApoE(-/-) mice aged 12 weeks (young) and 52 weeks (early stage of senescence). TBARS in plasma and liver were significantly increased by aging. Next, we examined the reasons why lipid peroxidation was promoted by aging, based on measurement of protein and mRNA levels for antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase) in liver in ApoE(-/-) mice aged 12 and 52 weeks. The levels of superoxide dismutase 1 and 2 in liver were significantly decreased by aging. The mRNA level of catalase was also significantly decreased and the mRNA levels of superoxide dismutase 1, superoxide dismutase 2 and glutathione peroxidase 1 all showed a tendency to decrease with age. These results suggest that lipid peroxidation is caused by reduction of antioxidant activity with aging and that this promotes senescence and shortens lifespan in ApoE(-/-) mice.
    Journal of Clinical Biochemistry and Nutrition 05/2013; 52(3):234-240. · 2.25 Impact Factor
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    ABSTRACT: Recently, we administered fish oil containing eicosapentaenoic acid and docosahexaenoic acid (DHA) to senescence-accelerated mice P8 (SAMP8), in order to investigate the effects on lifespan. Surprisingly, the lifespan of SAMP8 that were fed fish oil was shortened significantly, through a mechanism that likely involved lipid peroxidation. In this study, we investigated this phenomenon in further detail. To examine whether this phenomenon occurs only in SAMP8, we investigated the effect of fish oil on the lifespan of another organism species, Caenorhabditis elegans (C. elegans). C. elegans fed fish oil were cultured and the lifespan monitored. As a consequence of the provision of large amounts of fish oil the lifespan of C. elegans was shortened significantly, whereas an appropriate amount of fish oil extended their lifespan significantly. Lipid peroxide levels in C. elegans that were fed fish oil increased significantly in a dose-dependent manner. However, lipid peroxide levels in C. elegans were inhibited by the addition of fish oil and an antioxidant, α-tocopherol, and completely abrogated the changes in the lifespan. To further confirm whether the oxidation of n-3 polyunsaturated fatty acid in fish oil would change the lifespan of C. elegans, the effect of oxidized DHA was examined. Large amounts of oxidized DHA were found to shorten their lifespan significantly. Thus, fish oil changes the lifespan of C. elegans through lipid peroxidation.
    Journal of Clinical Biochemistry and Nutrition 03/2013; 52(2):139-45. · 2.25 Impact Factor
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    ABSTRACT: The maternal nutritional status during pregnancy and lactation influences the risk of obesity in offspring, but the details of this phenomenon are unclear. In particular, there is little information on the influence on the offspring of the maternal nutritional status during lactation only. Therefore, in this study, we examined the influence of high dietary fat intake in dams during lactation on the risk of obesity in offspring, using C57BL/6J mice. The mice were fed a control diet (CD) during pregnancy. After birth, dams were fed a CD or a high-fat diet (HD) during lactation (3 wk). Fat and energy were significantly increased in milk from dams fed a HD during lactation. Male offspring were weaned at 3 wk old and fed a CD for 4 wk, which resulted in no significant difference in their physique. Four weeks after weaning, the offspring (7 wk old) were fed a CD or HD for 4 wk to induce obesity. High dietary fat intake in dams and offspring promoted lipid accumulation in white adipose tissue and adipocyte hypertrophy in male offspring. The underlying mechanism may involve an increase in expression of Lpl and a decrease in expression of Hsl in white adipose tissue of offspring. In conclusion, our results show that high dietary fat intake during lactation promotes development of diet-induced obesity in male offspring.
    Journal of Nutritional Science and Vitaminology 01/2013; 59(5):384-92. · 0.99 Impact Factor
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    ABSTRACT: We have shown previously that jacaric acid (JA; 8c,10t,12c-18:3), which has a conjugated triene system, has a strong anti-tumor effect. However, the characteristics of absorption and metabolism of JA have yet to be determined in vivo, and the details of absorption and metabolism of JA in the small intestine are particularly unclear. This information is required for effective use of JA in humans. Therefore, in this study we examined absorption and metabolism of JA using cannulation of the thoracic duct in rats. Emulsions of two test oils, jacaranda seed oil and tung oil, which contain JA and α-eleostearic acid (α-ESA; 9c,11t,13t-18:3), respectively, were administered to rats and lymph from the thoracic duct was collected over 24 h. We examined the rate of absorption of JA and possible conversion to a conjugated linoleic acid (CLA)containing a conjugated diene system. The positional isomerism of the CLA produced by JA metabolism was determined using gas chromatography-electron impact/mass spectrometry. The rate of absorption and percentage conversion of JA were compared with those of α-ESA. We found that JA is rapidly absorbed and converted to a CLA in rats and that the percentage conversion of JA was lower than that of α-ESA. This is the first report on the absorption and metabolism of JA and this information may be important for application of JA as a functional food.
    Journal of oleo science 01/2013; 62(5):305-12. · 1.24 Impact Factor
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    ABSTRACT: In this study, we compared the cytotoxic effects of natural conjugated linolenic acids (CLnAs) on human adenocarcinoma cells (DLD-1) in vitro, with the goal of finding CLnA isomers with strong cytotoxic effects. The antitumor effect of the CLnA with the strongest cytotoxic effect was then examined in mice. The results showed that all CLnA isomers have strong cytotoxic effects on DLD-1 cells, with jacaric acid (JA) having the strongest effect. Examination of the mechanism of cell death showed that CLnAs induce apoptosis in DLD-1 cells via lipid peroxidation. The intracellular levels of incorporated CLnAs were measured to examine the reason for differences in cytotoxic effects. These results showed that JA was taken into cells efficiently. Collectively, these results suggest that the cytotoxic effect of CLnAs is dependent on intracellular incorporation and induction of apoptosis via lipid peroxidation. JA also had a strong preventive antitumor effect in vivo in nude mice into which DLD-1 cells were transplanted. These results suggest that JA can be used as a dietary constituent for prevention of cancer.
    Biochimica et Biophysica Acta 04/2012; 1821(7):980-8. · 4.66 Impact Factor
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    ABSTRACT: Conjugated fatty acid is a collective term used for fatty acids with conjugated double bond systems. Seed oils from certain plants include conjugated linolenic acids, which have a conjugated triene system and are geometrical and positional isomers of α-linolenic acid. One of these isomers, jacaric acid (JA, 8c, 10t, 12c-18:3), has not been examined widely. Therefore, we investigated the absorption and metabolism of JA in normal animals (ICR mice). An oral dose of JA of 5 mg/day for 1 week had no effects on body weight, food intake and tissue weight of mice. JA was detected in the serum, kidney, liver, lung and epididymal white adipose tissue. Analysis of the fatty acid composition in liver and white adipose tissue showed a tendency to increase levels of saturated fatty acids (SFAs) such as palmitic acid (16:0) and stearic acid (18:0) and to decrease levels of monounsaturated fatty acids (MUFAs) such as palmitoleic acid (16:1) and oleic acid (18:1). Thus, JA treatment decreased the desaturation index (16:1/16:0, 18:1/18:0) in liver and white adipose tissue. This index is used as an indicator of the activity of stearoyl coenzyme A desaturase (SCD), an endoplasmic reticulum enzyme that catalyzes the biosynthesis of MUFAs from SFAs. The change in this index indicates that JA inhibited SCD activity in ICR mice, and further experiments showed that JA also decreased the expression level of SCD-1 mRNA. Inhibition of SCD activity may have anti-obesity and anti-diabetes effects, and therefore the findings in this study suggest that JA may be effective for preventing obesity and diabetes.
    Journal of oleo science 01/2012; 61(8):433-41. · 1.24 Impact Factor
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    ABSTRACT: An understanding of the mechanisms of aging is important for prevention of age-related diseases. In this study, we examined age-dependent changes in lipid metabolism in the senescence-accelerated mouse (SAM)P10 fed a high-fat diet to investigate the effects of high-fat intake and aging. Tissue weights and biological parameters in plasma and liver were measured at 6 and 12 months old in SAMP10 mice fed a high-fat diet. These mice showed marked increases in liver triacylglycerol and plasma insulin levels with intake of a high-fat diet intake and aging. Lipid accumulation in hepatocytes and morphological aberrations and hypertrophy in pancreatic islets were also promoted by a high-fat diet and aging. To investigate the underlying mechanisms, the activities and mRNA levels for enzymes associated with lipid metabolism in liver were measured. The results indicated that the lipid metabolic system was activated by a high-fat diet and aging. Liver mRNA level for hydroxysteroid 11-beta dehydrogenase 1 (Hsd11b1), which exhibit age-dependent increases and promote insulin secretion, was also markedly increased. These results suggest that a high-fat diet accelerated aging in the liver of SAMP10 mice by increasing liver mRNA level for Hsd11b1, increasing insulin secretion, and promoting lipid accumulation in the liver.
    Biogerontology 10/2011; 13(2):93-103. · 3.19 Impact Factor