PubMed Health⌕ Search

Biomedical subjects

Masaya Kato

Publications and source records attributed to Masaya Kato.

16 recordsLinked to original sources
PubMed2006

The role of carotenoid cleavage dioxygenases in the regulation of carotenoid profiles during maturation in citrus fruit.

To investigate the relationship between a carotenoid profile and gene expression for carotenoid cleavage dioxygenases, three citrus varieties that exhibit different 9-cis-violaxanthin levels in their juice sacs, Satsuma mandarin (Citrus unshiu Marc.; a variety accumulating a low level of 9-cis-violaxanthin), Valencia orange (Citrus sinensis Osbeck; variety accumulating a high level of 9-cis-violaxanthin), and Lisbon lemon (Citrus limon Burm.f.; a variety accumulating an undetectable level of 9-cis-violaxanthin) were used. Three cDNAs (CitCCD1, CitNCED2, and CitNCED3) were cloned. The recombinant CitCCD1 protein cleaved beta-cryptoxanthin, zeaxanthin, and all-trans-violaxanthin at the 9-10 and 9'-10' positions and 9-cis-violaxanthin at the 9'-10' position. The recombinant CitNCED2 and CitNCED3 proteins cleaved 9-cis-violaxanthin at the 11-12 position to form xanthoxin, a precursor of abscisic acid (ABA). The gene expression of CitCCD1 increased in the flavedos and juice sacs of the three varieties during maturation. In Satsuma mandarin, the gene expression of CitNCED2 and CitNCED3 increased noticeably, accompanying a massive accumulation of ABA in the flavedo and juice sacs. In Valencia orange, the gene expression of CitNCED3 increased with a slight elevation of the ABA level in the flavedo, whereas neither the gene expression of CitNCED2 nor the ABA level increased noticeably in the juice sacs. In Lisbon lemon, the gene expression of CitNCED2 increased remarkably, accompanying increases in the ABA level in the flavedo and juice sacs. These results suggest that, in the juice sacs, the efficient cleavage reaction for ABA synthesis reduces the 9-cis-violaxanthin level in Satsuma mandarin and Lisbon lemon, whereas the low cleavage reaction maintains the predominant 9-cis-violaxanthin accumulation in Valencia orange.

Abscisic Acid↗
PubMed2006

Plain computed tomography for assessment of early coronary microcirculatory damage after revascularization therapy in acute myocardial infarction.

BACKGROUND: Coronary microcirculatory damage is an important factor for the prognosis for acute myocardial infarction (MI) after revascularization. The myocardial enhancement area with contrast media infused during coronary revascularization therapy, detected by computed tomography (CT) just after revascularization, has been reported to correspond to the area of hemorrhagic infarction. The relationship between myocardial contrast enhancement and coronary microcirculatory damage was investigated in the present study. METHODS AND RESULTS: Thirteen patients with acute anterior MI underwent successful coronary revascularization within 6 h of symptom onset were enrolled. The coronary flow velocity pattern was measured using a Doppler guidewire and chest CT assessments were performed immediately after coronary revascularization. The ratio of mean CT number of the highest-enhanced myocardial area and the lumen of the left ventricle was defined as a relative CT number. The relative CT number significantly correlated with coronary diastolic deceleration time (r=-0.78, p<0.002) and coronary diastolic deceleration rate (r=0.74, p<0.04). It also correlated with peak myocardial enzyme release in plasma. CONCLUSION: Myocardial contrast enhancement detected using plain CT just after coronary reperfusion therapy implies coronary microcirculatory damage in acute MI. The relative CT number is useful in evaluating the impaired coronary microcirculatory state.

Acute Disease↗
PubMed2006

The homeostasis model assessment-insulin resistance index is inversely associated with serum carotenoids in non-diabetic subjects.

BACKGROUND: Carotenoids may reduce the risk for diabetes mellitus, but little is known about the association of insulin resistance with serum carotenoids in non-diabetic subjects. This study aimed to investigate whether the homeostasis model assessment-insulin resistance (HOMA-IR) index would be lower in the presence of high serum carotenoid concentrations in non-diabetic subjects. METHODS: A total of 812 subjects (256 males and 556 females) who had received health examinations in 2003 participated in the study. The associations of the serum-carotenoid concentrations and HOMA-IR were evaluated cross-sectionally. The multivariate-adjusted geometric means of HOMA-IR by the tertiles of the serum carotenoid concentration were calculated after adjusting for age, body mass index, systolic blood pressure, total cholesterol, triacylglycerols, current tobacco use, regular alcohol intake, exercise habits and total energy intake. Associations among high HOMA-IR (3.0+mUxmmol/L2) across tertiles of serum carotenoid concentration were assessed by tests for logistic regression analysis. RESULTS: In male subjects, the multivariate adjusted geometric mean of HOMA-IR was inversely associated with the serum beta-cryptoxanthin concentrations. In female subjects, an inverse association of the serum carotenoid concentration and HOMA-IR was observed in lycopene, beta-cryptoxanthin, and zeaxanthin. The confounding factor-adjusted odds ratios (OR) for high HOMA-IR on the highest tertiles of serum alpha-carotene, beta-carotene, beta-cryptoxanthin, and zeaxanthin were 0.18 [95% confidence interval (CI): 0.06-0.52], 0.22 (95% CI: 0.07-0.67), 0.34 (95% CI: 0.12-0.96), and 0.30 (95% CI: 0.11-0.79), respectively, in male subjects. On the other hand, in female subjects, the adjusted OR for high HOMA-IR on the highest tertiles of serum lycopene and beta-cryptoxanthin were 0.39 (95% CI: 0.21-0.73) and 0.51 (95% CI: 0.28-0.95), respectively. CONCLUSIONS: The serum antioxidant carotenoids were inversely associated with HOMA-estimated insulin resistance in non-diabetic subjects.

Adult↗
PubMed2005

Serum carotenoid concentrations are inversely associated with serum aminotransferases in hyperglycemic subjects.

Hyperglycemia increases the generation of free radicals by glucose auto-oxidation, and the increment of free radicals may lead to liver cell damage. In this study, we tested the hypothesis that hyperglycemia-induced increases of serum liver enzymes among its physiological concentration would be inversely associated with serum antioxidant carotenoid level. Study subjects were 857 male and female Japanese who had received health examinations in 2003. Those with a history of liver disease and excessive alcohol drinkers were excluded. The associations of serum six-carotenoid concentrations with serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) stratified by glucose tolerance status were evaluated cross-sectionally. Serum AST and ALT concentrations in the groups of impaired fasting glucose (IFG) and diabetes were significantly higher than those in the normal group. The multivariate-adjusted means of the serum AST and ALT concentrations in IFG and diabetes group were significantly low in accordance with the tertiles of the serum beta-cryptoxanthin and beta-carotene concentrations. The most inverse association of serum liver enzyme and carotenoid concentration was observed in beta-cryptoxanthin. Antioxidant carotenoid, especially beta-cryptoxanthin, may act a deterrent substance against increasing the serum aminotransferase in the earlier pathogenesis of liver dysfunction among hyperglycemic subjects.

Alanine Transaminase↗
PubMed2005

Efficient gene silencing and cell differentiation using siRNA in mouse and monkey ES cells.

Small interfering RNA (siRNA) has been widely used for suppressing gene expression in various organisms. Here, we describe efficient methods to suppress target genes (EGFP or Oct4) using siRNA in mouse and monkey ES cells, and differentiation. In mouse ES cells, FACS analysis revealed that EGFP expression was suppressed in 97% of transfected cells at 48 h after transfection. In addition, cells expressed Hand1 and Cdx2, which are the marker genes of trophoblast lineage by the transient suppression of Oct4. In the case of monkey ES cells, highly efficient suppression was achieved in 98% of cells at 96 h post-transfection using the Sendai virus (hemagglutinating virus of Japan, HVJ) envelope as a carrier of siRNA. These efficient transfection methods using synthetic siRNA should contribute to evaluate specific gene function in ES cells and can be used to differentiate ES cells into desired cell lineages.

Animals↗
PubMed2005

Determination of the optimal atrioventricular interval in sick sinus syndrome during DDD pacing.

BACKGROUND: Although the AAI pacing mode has been shown to be electromechanically superior to the DDD pacing mode in sick sinus syndrome (SSS), there is evidence suggesting that during AAI pacing the presence of natural ventricular activation pattern is not enough for hemodynamic benefit to occur. Myocardial performance index (MPI) is a simply measurable Doppler-derived index of combined systolic and diastolic myocardial performance. The aim of this study was to investigate whether AAI pacing mode is electromechanically superior to the DDD mode in patients with SSS by using Doppler-derived MPI. METHODS: Thirty-nine SSS patients with dual-chamber pacing devices were evaluated by using Doppler echocardiography in AAI mode and DDD mode. The optimal atrioventricular (AV) interval in DDD mode was determined and atrial stimulus-R interval was measured in AAI mode. The ratio of the atrial stimulus-R interval to the optimal AV interval was defined as relative AV interval (rAVI) and the ratio of MPI in AAI mode to that in DDD mode was defined as relative MPI (rMPI). RESULTS: The rMPI was significantly correlated with atrial stimulus-R interval and rAVI (r = 0.57, P = 0.0002, and r = 0.67, P < 0.0001, respectively). A cutoff point of 1.73 for rAVI provided optimum sensitivity and specificity for rMPI >1 based on the receiver operator curves. CONCLUSIONS: Even though the intrinsic AV conduction is moderately prolonged, some SSS patients with dual-chamber pacing devices benefit from the ventricular pacing with optimal AV interval. MPI is useful to determine the optimal pacing mode in acute experiment.

Aged↗
PubMed2005

High serum carotenoids are inversely associated with serum gamma-glutamyltransferase in alcohol drinkers within normal liver function.

BACKGROUND: Many studies have reported that the consumption of alcohol induces the generation of free radicals. Moreover, recent studies suggest that serum gamma-glutamyltransferase (gamma-GTP) within its normal range might be an early marker of oxidative stress. In this study, we tested the hypothesis that serum antioxidant carotenoids would be inversely associated with serum gamma-GTP in alcohol drinkers within normal liver function. METHODS: A total of 266 Japanese men who had received health examination in 2003 participated in the study. The associations of serum gamma-GTP and serum-carotenoid concentrations stratified by alcohol intake levels were evaluated cross-sectionally. The participants were divided into three groups according to their ethanol intake level (non-drinker, less than 1 g/day; light drinker, 1-25 g/day; and moderate and heavy drinkers, 25+ g/day). The multivariate-adjusted geometric means of the serum gamma-GTP concentrations in each tertile of the serum-carotenoid concentrations were calculated after adjustment for ethanol intake, age, body mass index, total cholesterol, triacylglycerols, current tobacco use, and habitual exercise. RESULTS: The serum gamma-GTP concentrations were significantly high in accordance with the ethanol intake level. In moderate and heavy drinkers, the multivariate-adjusted geometric means of serum gamma-GTP concentrations were significantly low in accordance with the tertiles of the serum lycopene, alpha-carotene, beta-carotene, and beta-cryptoxanthin concentrations. CONCLUSIONS: The serum antioxidant carotenoids were inversely associated with alcohol-induced increases of serum gamma-GTP in moderate and heavy drinkers within normal liver function.

Adult↗
PubMed2004

Effect of sucrose on ascorbate level and expression of genes involved in the ascorbate biosynthesis and recycling pathway in harvested broccoli florets.

The relationship between sucrose (Suc) and ascorbate (AA) metabolism was investigated in harvested broccoli (Brassica oleracea L. var. italica) florets. Decreases in both Suc and AA content were observed in broccoli florets 48 h after all the leaves were excised, but none were observed when the plants were kept intact or with leaves attached in a room at 20 degrees C. In harvested broccoli plants without leaves and roots, continuous absorption of a 10% (w/v) Suc solution from the cut surface of the stem suppressed the degreening of sepals and the loss of AA content in florets. The expression of the genes related to AA metabolism in chloroplasts and its biosynthesis were up-regulated by Suc feeding in broccoli florets. These data suggest that a decline in Suc leads to considerable damage not only to AA biosynthesis but also to the hydrogen peroxide-scavenging system in chloroplasts. In addition, the cessation of the Suc supply from leaves can be the main factor of AA degradation in harvested broccoli florets.

Ascorbic Acid↗
PubMed2004

Accumulation of carotenoids and expression of carotenoid biosynthetic genes during maturation in citrus fruit.

The relationship between carotenoid accumulation and the expression of carotenoid biosynthetic genes during fruit maturation was investigated in three citrus varieties, Satsuma mandarin (Citrus unshiu Marc.), Valencia orange (Citrus sinensis Osbeck), and Lisbon lemon (Citrus limon Burm.f.). We cloned the cDNAs for phytoene synthase (CitPSY), phytoene desaturase (CitPDS), zeta-carotene (car) desaturase (CitZDS), carotenoid isomerase (CitCRTISO), lycopene beta-cyclase (CitLCYb), beta-ring hydroxylase (CitHYb), zeaxanthin (zea) epoxidase (CitZEP), and lycopene epsilon-cyclase (CitLCYe) from Satsuma mandarin, which shared high identities in nucleotide sequences with Valencia orange, Lisbon lemon, and other plant species. With the transition of peel color from green to orange, the change from beta,epsilon-carotenoid (alpha-car and lutein) accumulation to beta,beta-carotenoid (beta-car, beta-cryptoxanthin, zea, and violaxanthin) accumulation was observed in the flavedos of Satsuma mandarin and Valencia orange, accompanying the disappearance of CitLCYe transcripts and the increase in CitLCYb transcripts. Even in green fruit, high levels of beta,epsilon-carotenoids and CitLCYe transcripts were not observed in the juice sacs. As fruit maturation progressed in Satsuma mandarin and Valencia orange, a simultaneous increase in the expression of genes (CitPSY, CitPDS, CitZDS, CitLCYb, CitHYb, and CitZEP) led to massive beta,beta-xanthophyll (beta-cryptoxanthin, zea, and violaxanthin) accumulation in both the flavedo and juice sacs. The gene expression of CitCRTISO was kept low or decreased in the flavedo during massive beta,beta-xanthophyll accumulation. In the flavedo of Lisbon lemon and Satsuma mandarin, massive accumulation of phytoene was observed with a decrease in the transcript level for CitPDS. Thus, the carotenoid accumulation during citrus fruit maturation was highly regulated by the coordination of the expression among carotenoid biosynthetic genes. In this paper, the mechanism leading to diversity in beta,beta-xanthophyll compositions between Satsuma mandarin and Valencia orange was also discussed on the basis of the substrate specificity of beta-ring hydroxylase and the balance of expression between upstream synthesis genes (CitPSY, CitPDS, CitZDS, and CitLCYb) and downstream synthesis genes (CitHYb and CitZEP).

Alkyl and Aryl Transferases↗
PubMed2004

Intracoronary verapamil rapidly terminates reperfusion tachyarrhythmias in acute myocardial infarction.

BACKGROUND: The restoration of coronary flow after transient ischemia immediately induces life-threatening ventricular tachyarrhythmias. Although most of these arrhythmias disappear spontaneously, some of them induce serious hemodynamic changes. This retrospective study investigates the efficacy of therapy with intracoronary verapamil to terminate reperfusion-induced ventricular tachyarrhythmias in patients with acute myocardial infarction (AMI). METHODS AND RESULTS: Between February 1992 and February 2003, 390 patients with a diagnosis of AMI were enrolled into the study. All patients received mechanical revascularization therapy within 6 h of onset of symptoms, and 109 patients experienced reperfusion-induced tachyarrhythmias. A subset of these patients was treated with intracoronary verapamil (0.25 to 1.0 mg) to terminate the reperfusion-induced tachyarrhythmia. They were evaluated for immediate termination of the tachyarrhythmias, hemodynamic changes, resumption rates, and major complications. Thirty-one patients (28%) were treated with intracoronary verapamil for the immediate termination of reperfusion-induced ventricular tachyarrhythmias. These tachyarrhythmias included 6 premature ventricular contractions, 19 accelerated idioventricular rhythms, 3 ventricular tachycardias, 2 ventricular fibrillations (VFs), and 1 torsades de pointes. Intracoronary verapamil was effective in rapidly terminating all reperfusion-induced arrhythmias except for VFs. The side effects of treatment included temporary hypotension (two patients) and bradycardia (one patient), although all patients recovered spontaneously. No major complications were induced by the intracoronary use of verapamil, and no resumptions of arrhythmias were documented. CONCLUSION: Intracoronary administration of verapamil can safely terminate reperfusion-induced ventricular tachyarrhythmias in a rapid manner. However, this effect was not seen for reperfusion-induced VF.

Adult↗
PubMed2004

Multiple linear regression analysis of the seasonal changes in the serum concentration of beta-cryptoxanthin.

Beta-cryptoxanthin (beta-CRX) is a carotenoid pigment found in Satsuma mandarin (Citrus unshiu Marc.) fruit, which is heavily produced in Japan. In this study, we evaluated the seasonal changes in the serum beta-CRX level and investigated predictors of serum beta-CRX level by multiple linear regression analysis. Blood tests and self-administered questionnaires were used every other month for one year. The subjects were healthy volunteers, 15 males and 12 females. The serum beta-CRX levels increased dramatically as the intake of Satsuma mandarin increased; the maximum increase was noted in January. Multiple linear regression analysis showed that, in males, the serum beta-CRX level could be predicted by Satsuma mandarin intake, age and the month of blood sampling; however, it was inversely associated with alcohol and smoking habits. Conversely, in females, the serum beta-CRX concentration could be predicted by Satsuma mandarin intake, the month of blood sampling and age; however, it was inversely associated with body mass index. The results of multiple linear regression analysis suggest that the serum beta-CRX levels can be used to evaluate the intake volume of Satsuma mandarin. Furthermore, beta-CRX is a useful biomarker to estimate the beneficial effects of Satsuma mandarin intake in epidemiological studies.

Adult↗
PubMed2004

Seasonal changes in the relationship between serum concentration of beta-cryptoxanthin and serum lipid levels.

Beta-cryptoxanthin (beta-CRX) is a carotenoid pigment found especially in Satsuma mandarin (Citrus unshiu Marc.) fruit, which is mainly produced in Japan. Previously, we found that serum beta-CRX concentrations rose to extreme levels as the frequency of consumption of Satsuma mandarin increases. Using 94 non-smoking female volunteers, the present study evaluated the relationship between serum concentration of beta-CRX and serum lipid levels in September, when the Satsuma mandarin is not in season, and in January of the next year, when it is in season. The mean of increment in serum beta-CRX concentrations from September to January was 95.9 +/- 84.0 microg/dl (mean +/- SD). Although the changes in serum lipid levels did not correlate with the changes in serum beta-CRX, the serum HDL-cholesterol and apo-lipoprotein A1 levels in the highest quartile of the increment in serum beta-CRX from September to January were significantly higher than those in the lowest quartile in both September and January. In cross-sectional analyses, serum beta-CRX concentrations were correlated positively with those of LDL-cholesterol and apo-lipoprotein B levels in September, but these correlations were not observed in January. In contrast, serum beta-CRX concentrations were correlated positively with those of HDL-cholesterol and apo-lipoprotein A1 levels in January. These results suggest that habitual eating of Satsuma mandarin while it is in season may influence lipid metabolism throughout the year.

Apolipoprotein A-I↗
PubMed2003

Ascorbate metabolism in harvested broccoli.

The ascorbate content declined rapidly in broccoli (Brassica oleracea L. var. italica) florets, but not in the stem tissue, during post-harvest senescence. Ascorbate peroxidase (APX), ascorbate oxidase (AO), l-galactono-1,4-lactone dehydrogenase (GLDH), monodehydroascorbate reductase (MDAR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR) were investigated in gene expression after harvest in both florets and the stem tissue of broccoli. Cytosolic gene expressions (BO-APX 1, BO-APX 2, BO-AO, BO-MDAR 2, and BO-GR) were stimulated actively in broccoli florets after harvest. By contrast, it was observed that mRNA levels of chloroplastic APX, BO-sAPX and BO-tbAPX, had decreased by 12 h after harvest in broccoli florets, suggesting that the active oxygen species (AOS) scavenging system in chloroplasts was largely abolished in florets during the early hours of the post-harvest period. In addition, gene expressions in GLDH and other chloroplastic enzymes such as BO-MDAR 1 and BO-DHAR decreased rapidly within 24 h after harvest. Ethylene treatment had no effect on the ascorbate level and the expression of all genes investigated. The expressions of BO-GLDH and chloroplastic genes (BO-sAPX, BO-tbAPX, BO-MDAR 1, and BO-DHAR) mRNA were suppressed by treatment with methyl jasmonate (MJ) and abscisic acid (ABA) and were accompanied by the acceleration of ascorbate degradation. These data suggest that ascorbate metabolism tends to be inactivated in chloroplasts by transcriptional regulation, but not in the cytosol, when ascorbate decreases under stress conditions.

Ascorbate Oxidase↗
PubMed2003

Clinical implications of carotid artery remodeling in acute coronary syndrome: ultrasonographic assessment of positive remodeling.

OBJECTIVES: We investigated the relationship between ultrasonographic features of the carotid artery and the angiographic features of coronary plaques in acute coronary syndrome (ACS). BACKGROUND: The carotid intima-media thickness (IMT) may be a marker of advanced coronary artery disease. METHODS: Consecutive ACS patients (N = 125) underwent B-mode ultrasonography within one week of the acute coronary event. Using a 7.5-MHz linear array transducer, the common carotid IMT, interadventitial diameter, and luminal diameter were examined. Carotid plaques were also assessed. Then patients were divided into two groups based on the number of complex plaques identified by coronary angiography. RESULTS: The carotid IMT of 75 patients with multiple complex coronary plaques was significantly larger than that of 50 patients with solitary plaques (p < 0.0003). The prevalence of soft and hard carotid plaques was higher in the group with multiple coronary plaques than in those with single plaques (28% vs. 12%, p < 0.04 and 13% vs. 0%, p < 0.008, respectively). Additionally, the carotid interadventitial diameter was larger in the patients with multiple plaques than in those with single plaques (7.93 +/- 0.97 mm vs. 7.48 +/- 0.88 mm, p < 0.01), and a significant correlation was observed between the carotid IMT and interadventitial diameter (R = 0.54, p < 0.0001). CONCLUSIONS: In ACS, multiple complex coronary plaques are associated with positive carotid remodeling, suggesting that plaque vulnerability may be a systemic phenomenon.

Acute Disease↗
PubMed2003

Inhibitory effects of basic drugs on the sodium-dependent transport of L-alanine via system B0 in the small intestine.

To elucidate the mechanism of the interaction of basic drugs with Na(+)-dependent L-alanine absorption from the small intestine, we investigated the effect of imipramine on the transport of L-alanine via system B(0), which is thought to be one of the main Na(+)-dependent systems for intestinal absorption of short-chain neutral amino acids, including L-alanine. The uptake of L-alanine by cells that express hATB(0) (human amino acid transporter B(0)) was inhibited in the presence of imipramine. The Eadie-Hofstee plot showed that the inhibition was not competitive with the substrate (L-alanine) but competitive with Na(+). When rat intestinal brush border membrane vesicles were used, several basic drugs had inhibitory effects. Inhibition was also observed in intestinal absorption evaluated by an in situ single-pass perfusion technique. However, the potencies of inhibition were different. The potency of inhibition was dependent on the lipophilicity of the drugs.

Journal Article↗