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Biomedical subjects

Y Sawa

Publications and source records attributed to Y Sawa.

At least 181 records · Page 10Linked to original sources
PubMed1995

Chlorogenic acid as a natural scavenger for hypochlorous acid.

The effect of chlorogenic acid (CGA) on the killing of Escherichia coli by hypochlorous acid (HOCI) was examined. CGA prevented E. coli from bactericidal action of HOCI in a concentration-dependent manner. HOCI reacted rapidly with CGA. By comparison with the one- and two-electron oxidation products produced by peroxidase and phenolase reactions, respectively, the main product was identified as o-quinone of CGA via the formation of o-semiquinone of CGA as an intermediate The quinone form of CGA reacted further with HOCI to yield unstable product(s).

Blood Bactericidal Activity↗
PubMed1995

The suppression of the N-nitrosating reaction by chlorogenic acid.

N-Nitrosation of a model aromatic amine (2,3-diamino-naphthalene) by the N-nitrosating agent produced by nitrite in acidic solution was inhibited by a polyphenol, chlorogenic acid, which is an ester of caffeic acid quinic acid. Caffeic acid also inhibited the N-nitrosation, but quinic acid did not. 1,2-Benzenediols and 3,4-dihydroxybenzoic acid had inhibitory activities. Chlorogenic acid, caffeic acid, 1,2-benzenediols and 3,4-dihydroxybenzoic acid were able to scavenge the stable free radical, 1,1-diphenyl-2-picrylhydrazyl. Chlorogenic acid was found to be nitrated by acidic nitrite. The kinetic studies and the nitration observed only by bubbling of nitric oxide plus nitrogen dioxide gases indicated that the nitrating agent was nitrogen sesquioxide. The observations showed that the mechanism by which chlorogenic acid inhibited N-nitrosation of 2,3-diamino-naphthalene is due to its ability to scavenge the nitrosating agent, nitrogen sesquioxide. Chlorogenic acid may be effective not only in protecting against oxidative damage but also in inhibiting potentially mutagenic and carcinogenic reactions in vivo.

2-Naphthylamine↗
PubMed1995

Supplement of nitric oxide attenuates neutrophil-mediated reperfusion injury.

BACKGROUND: Nitric oxide (NO) derived from the endothelial cell has been identified as a constitutive chemical mediator that regulates the function of the endothelial cell in association with neutrophil (PMN) adhesion and activation. However, its role in the pathogenesis of myocardial reperfusion injury is not clear. METHODS AND RESULTS: Fifteen isolated rat hearts were perfused with modified Krebs-Henseleit solution and subjected to 20 minutes of global and normothermic ischemia. Then the hearts were reperfused for 45 minutes with different protocols: the control (C) group was reperfused without PMNs, the P group was reperfused with PMNs, and the N group was reperfused with PMNs and nitroprusside (10(-5) mol/L). The ozone chemiluminescence method was used for direct measurement of NO in the coronary effluent during reperfusion. NO in the coronary effluent in the C group decreased at reperfusion after normoxic perfusion, and this decrease in NO continued for the first 15 minutes of reperfusion. Percentage recovery of left ventricular developed pressure and coronary flow was significantly lower in the P group than that in the N group. Also, the N group had a significantly lesser Luminol-elicited chemiluminescence of the coronary effluent and ratio of PMN adherence to myocardial vasculature compared with the P group. CONCLUSIONS: This study demonstrated directly the decrease in NO production during reperfusion and showed that supplement of NO with NO donor attenuated the injury in which PMNs were involved. The results suggest that NO plays a significant role in reperfusion injury and that supplement of NO during reperfusion appears to be useful to attenuate this injury.

Animals↗
PubMed1995

Efficiency of in vivo gene transfection into transplanted rat heart by coronary infusion of HVJ liposome.

BACKGROUND: Current methods of in vivo gene transfer into myocardium are limited by low efficiency. To improve in vivo gene transfer, a gene transfer method using hemagglutinating virus of Japan (HVJ) as a viral vector can be an alternative. METHODS AND RESULTS: In vivo gene transfection of FITC-labeled oligonucleotide (F-ODN) and cDNA of beta-galactosidase (beta-gal) was examined with use of the HVJ liposome (H group) or without it (C group). In the H group, F-ODN or cDNA of beta-gal were complexed with liposomes, DNA binding nuclear protein (HMG1), and the viral protein coat of HVJ. After the harvest of donor rat hearts arrested by cardioplegia, the coronary artery was infused with the liposome gene complex. The hearts were transplanted into the abdomens of recipient rats and harvested 3 days after transplantation. Regarding F-ODN, the H group clearly showed FITC staining in the nuclei of the myocytes and endothelial cells in almost all layers of the myocardium as compared with the C group. Regarding the expression of beta-gal, the H group showed a clear expression of beta-gal on myocytes, whereas very low expression of beta-gal was seen in the C group. CONCLUSIONS: The donor hearts were transfected with F-ODN and beta-gal gene in almost all layers of the myocardium as a result of coronary infusion of the HVJ liposome during cardioplegic arrest. Our method is seen as a novel in vivo gene transfer technique for the heart and may provide a new tool for both research and therapy of heart transplantation.

Animals↗
PubMed1995

Steviol and steviol-glycoside: glucosyltransferase activities in Stevia rebaudiana Bertoni--purification and partial characterization.

The leaves of Stevia rebaudiana Bertoni contain sweet compounds which are glycosides of diterpene derivative steviol (ent-13-hydroxykaur-16-en-19-oic acid). Its main constituents are stevioside (triglucosylated steviol; 13-O-beta-sophorosyl-19-O-beta-glucosyl-steviol) and rebaudioside-A (tetraglucosylated steviol; 2'-O-beta-glucosyl-13-O-beta-sophorosyl-19-O-beta-glucosyl-stev iol). From the extracts of S. rebaudiana Bertoni, two glucosyltransferases (GTases I and IIB) acting on steviol and steviol-glycosides were isolated, and another distinct activity (GTase IIA) acting on steviol was detected. Purified GTase I (subunit M(r) 24,600) catalyzed glucose transfer from UDP-glucose to steviol and steviolmonoside (steviol-13-O-glucopyranoside), but not to other steviol-glycosides. Apparent Km values were 71.4 microM for steviol and 360 microM for UDP-glucose. GTase IIB (subunit M(r) 30,700) showed a broad substrate specificity, acting on steviol, steviolmonoside, steviolbioside (13-O-beta-sophorosyl-steviol), and stevioside. Apparent Km values were 182 microM for steviol, 44 microM for steviolbioside, 95 microM for stevioside, and 385 microM for UDP-glucose. The two enzymes had a similar optimum pH at 6.5. They also acted effectively on ubiquitous flavonol aglycones, quercetin, and kaempferol and utilized kaempferol at a higher rate than steviol and steviol-glycosides. The apparent Km values of GTase I and IIB for kaempferol were 12 and 31 microM, respectively.

Chromatography, Gel↗
PubMed1995

The enhancement of the human immunoglobulin G Fc fragment-binding activity of Mycoplasma salivarium cells by trypsin treatment is ascribed to the binding of trypsin to the Fc fragment.

Human immunoglobulin G Fc fragment-binding activity of Mycoplasma salivarium cells was remarkably enhanced by trypsin treatment of the cells. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis profile of proteins of the cells treated with trypsin was the same as that of the cells treated with pronase, although pronase treatment had been shown to reduce the activity in our previous study (FEMS Microbiol. Lett. 123, 305-310, 1994). This contradiction was clarified by the finding that trypsin bound the Fc fragment more strongly than the cells, and a small amount of trypsin remained in the cells treated with trypsin and washed well. On the basis of these results, it was concluded that the enhancement of cell activity by trypsin treatment was ascribed to binding of the Fc fragment to trypsin remaining in the trypsin-treated cells.

Immunoglobulin Fc Fragments↗
PubMed1995

Inhibition of Na+/H+ exchanger attenuates neutrophil-mediated reperfusion injury.

BACKGROUND: The effect of Na+/H+ exchange inhibition in neutrophil-induced reperfusion injury was investigated using a new amiloride analogue, 5-methyl-N-isobutyl amiloride (MIA). METHODS: Rat neutrophils were separated using Percoll gradient. Luminol chemiluminescence intensity of isolated neutrophils was depressed by MIA in a dose-dependent manner. RESULTS: The effect of MIA on neutrophil-induced reperfusion injury was evaluated in Langendorff-perfused rat hearts subjected to 30 minutes of normothermic ischemia. Postischemic left ventricular developed pressure recovery was depressed by the reperfusion with neutrophils (60% +/- 7% to 33% +/- 26%) and was reverted by MIA pretreatment (86% +/- 17%, p < 0.05). MIA also improved percent recovery of coronary flow (51% +/- 2% to 70% +/- 13%), reduced creatine kinase (0.28 +/- 0.1 to 0.085 +/- 0.03 IU.L-1.g-1 dry wt), and lactate dehydrogenase leakage (10.6 +/- 3.8 to 5.16 +/- 1.3 IU.L-1.g-1 dry wt) significantly. The incidence of reperfusion-induced ventricular fibrillation also was reduced by MIA. CONCLUSIONS: The inhibition of Na+/H+ exchange shows a protective effect against neutrophil-induced reperfusion injury possibly by inhibiting the activation of neutrophils.

Amiloride↗
PubMed1995

Augmented endogenous nitric oxide production in partial portal vein-ligated rats.

1. Endothelium-derived nitric oxide (NO) is a potent vasodilator. Because the body oxidizes it to nitrate ions, NO3-, measurement of the serum concentration and the urinary excretion of NO3- may be an index for endogenous NO. We investigated the role of NO on hyperdynamic circulation in cirrhotic and partial portal vein-ligated rats by measuring NO3. 2. Liver cirrhosis was induced by administration of thioacetamide. Systemic and splanchnic haemodynamics and splenic-systemic shunting were determined by tracer microspheres. The concentration of NO3- was measured by using high-performance liquid chromatography with an anioncolumn. 3. We found that systemic and splanchnic hyperdynamic circulation existed to almost the same extent in cirrhotic and in portal vein-ligated rats as compared to the controls and shamoperated rats, respectively. Splenic-systemic shunting was markedly greater in portal vein-ligated rats than in cirrhotic rats. 4. Serum NO3- levels and urinary excretion of NO3- in cirrhotic rats tended to increase as compared to the controls. On the other hand, the levels in portal vein-ligated rats were significantly increased as compared to those of the shamoperated rats, and were significantly and negatively correlated to the splanchnic arterial resistance and total vascular resistance. The amount of urinary excretion of NO3- significantly correlated to splenic-systemic shunting (r = 0.61, P < 0.05) only in portal vein-ligated rats. 5. We suggest that these high levels of NO3- in portal vein-ligated rats relate to the extensive formation of porto-collateral vasculature or acute changes in systemic and splanchnic haemodynamics due to portal vein-ligation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Structure and replication of cryptic plasmids, pMA1 and pMA2, from a unicellular cyanobacterium, Microcystis aeruginosa.

The 4993-bp cryptic plasmid, pMA2, from a cyanobacterium, Microcystis aeruginosa f. aeruginosa Kützing, originally derived from Kasumigaura lake, was completely sequenced and analyzed. Plasmid pMA2 had a unique sequence motif CTTGATT, which was proposed to be a nicking site on the smaller plasmid pMA1 (2287-bp) by the presence of single-stranded DNA susceptible to S1 nuclease. We had detected the occurrence of the single-stranded pMA1 in the living M. aeruginosa cells. This was also the case of pMA2. Thus, we suggest that both plasmids, pMA1 and pMA2, replicate through the rolling circle mechanism. By computer analysis of the pMA2 sequence, two open reading frames were found: one had a predicted molecular size of 30,440 Da and the other on a complementary one had a predicted molecular size of 10,852 Da. No rep protein was detected. Replication mechanisms of the plasmids are discussed.

Amino Acid Sequence↗
PubMed1995

[Effects of desipramine and clomipramine on alpha 2-adrenergic receptor function in nucleus accumbens: studies with intracerebral dialysis in freely moving rats].

The effect of alpha 2-adrenoceptor agonist, clonidine (CLN) (100 micrograms/kg, i.p.), on the noradrenalin metabolite 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG)-total in the rat nucleus accumbens after desipramine (DMI) (20 mg/kg, i.p.) and clomipramine (CMI) (20 mg/kg, i.p.) treatment was estimated in the freely moving rat by intracerebral dialysis. Locomotor activity was measured simultaneously by the Animex. Locomotor activity in the control decreased after CLN administration, in accordance with the decrease in MHPG. The difference of locomotor activity and MHPG between the single dose trial with DMI, CMI and the control did not reach statistical significance throughout the experiment. The results suggest that a single injection of DMI and CMI have not an inhibitory effect on presynaptic alpha 2-adrenergic receptor in the nucleus accumbens. Next, DMI (20 mg/kg, i.p.) and CMI (20 mg/kg, i.p.) were injected once daily for 14 days and experiments, the same method as used on the single dose trial. A difference in locomotor activity and MHPG between the chronic DMI treatment and the control reached statistical significance. A significant reduction of locomotor activity was found during the 60 min period of the experiment. In addition, a significant reduction of MHPG was found during the 30-90 min period. A difference in locomotor activity and MHPG between the chronic CMI treatment and the control reached statistical significance. A significant reduction of locomotor activity was found during the 60 min period of the experiment. In addition, a significant reduction of MHPG was found during the 30-120 min period. The results suggest that the chronic DMI treatment and the chronic CMI treatment may diminish the CLN-induced reduction of MHPG via the subsensitivity of presynaptic alpha 2-adrenergic receptor in the nucleus accumbens.

Adrenergic alpha-Agonists↗
PubMed1994

Membrane proteins with molecular masses of 88, 90 and 150 kDa are responsible for binding of human immunoglobulin G Fc fragment to the native cells of Mycoplasma salivarium.

Mycoplasma salivarium cells bound the Fc fragment of human immunoglobulin G. The activity was remarkably enhanced by Mn2+, but not by Mg2+ and Ca2+; significantly inhibited by D-mannose; and reduced by pronase treatment of the cells. About 90% of the cells treated with pronase were not disrupted. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of proteins of the cells treated with pronase indicated that proteins with molecular masses of 88, 90 and 150 kDa (88 kp, 90 kp and 150 kp) were specifically digested. The results presented suggest that 88 kp, 90 kp and 150 kp, located in the outer surface of the cell membrane, are responsible for the activity of the M. salivarium cells and interact with a carbohydrate-containing moiety (D-mannose) of the Fc fragment in a Mn(2+)-dependent manner.

Bacterial Outer Membrane Proteins↗
PubMed1994

Effect of p-chloroamphetamine administration on monoamine metabolism in the rat nucleus accumbens and locomotor activity: studies with intracerebral dialysis in freely moving rats.

Changes in the level of dopamine (DA) and its metabolites [3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA)] and serotonin (5-HT) and its metabolite [5-hydroxyindoleacetic acid (5-HIAA)] were determined sequentially in freely moving rats by using a brain dialysis method. The purpose of the study was to find the relationship between changes in the monoamine metabolism in the nucleus accumbens and locomotor activities following PCA administration. Subsequently it was found that locomotor activity significantly increased 1 and 2 h after PCA administration (2 mg/kg, i.p.) while the DA content in the dialysis fluid rose significantly after 1 and 2 h. On the other hand, the 5-HT level did not show significant changes. The DOPAC, HVA, and 5-HIAA levels were significantly reduced 1 to 6 h after PCA administration. It was suggested that the increase in locomotor activity caused by PCA administration is an expression of abnormal behavior caused by DA release from the nucleus accumbens.

Animals↗
PubMed1994

Analysis of rejection mechanism in the rat to mouse cardiac xenotransplantation. Role and characteristics of anti-endothelial cell antibodies.

Recent reports have demonstrated that humoral factors, especially antibodies elicited by xenoantigens, play an important role in the rejection of concordant cardiac xenografts. These induced antibodies, however, have not been well characterized. Therefore, we investigated the rejection mechanism, especially the role of humoral immunological responses in the concordant rat to mouse cardiac xenograft model. Lewis rat hearts transplanted into C3H/HeN mice were rejected in 5-6 days. The essential role of humoral factors in the rejection was demonstrated by histological analysis of the rejected hearts showing interstitial hemorrhage, scant cellular infiltration, and the dense deposition of mouse IgG, IgM, and C3 on the graft endothelial cells. In addition, mice that received hyperimmune serum (serum at the 10th day after transplantation) rejected rat hearts hyperacutely. Flow cytometrical analysis using cultured donor rat coronary endothelial cells demonstrated the xenoreactive antibodies of all subclasses, but especially strong reactivity of IgM and IgG2a in the serum at rejection. These xenoreactive antibodies were produced against not only MHC, but also non-MHC antigens on graft endothelial cells. In vivo depletion of L3T4+ T cells led to the suppression of xenoreactive antibody production and the prolongation of graft survival, indicating that antibody production in this model needs L3T4+ T cell help.

Animals↗
PubMed1994

Myocardial protective effect of deep hypothermic cardiac arrest without aortic cross clamp in neonatal hearts: comparison with cardioplegic arrest in a rabbit model.

Using an isolated perfusion model of neonatal rabbit hearts aged 3 to 6 days, cardioplegic arrest (CPA) using crystalloid cold cardioplegia with aortic cross clamp (AXC: 60 min, n = 15) and continuous deep hypothermic perfusion (DHP) at 15 degrees C without AXC (n = 15) were compared. The hearts were divided into two subgroups: intact hearts (n = 18) and with preceding 40 min warm ischemia (stressed hearts, n = 22). In the intact hearts, there were no significant differences between the CPA and DHP groups in left ventricular function, myocardial water content, and myocardial mitochondrial score after reperfusion. In the stressed hearts, recovery of cardiac output and left ventricular work was significantly higher in the DHP group than in the CPA group. The post-reperfusion myocardial mitochondrial score was significantly better in the DHP group than in the CPA group. These results suggest that non-AXC DHP may be advantageous in the setting of stressed hearts with preceding ischemic injury where conventional CPA cannot provide adequate myocardial protection.

Animals↗
PubMed1994

Hemodynamic effects of combined treatment with somatostatin analogue (SMS 201-995) and low-dose isosorbide dinitrate on portal hypertension in conscious cirrhotic rats.

The authors investigated whether combined treatment with the somatostatin analogue, SMS 201-995, and low-dose isosorbide dinitrate enhanced the hemodynamic effects of the individual agents on rats with thioacetamide-induced cirrhosis. Four groups of cirrhotic rats received SMS 201-995 (0.1 microgram.min-1.kg-1), isosorbide dinitrate (10 micrograms.min-1.kg-1), both agents, or placebo, respectively. Hemodynamics were measured serially in conscious rats, using a radioactive microsphere method. SMS 201-995 reduced portal venous inflow 21 +/- 4% and portal pressure 17 +/- 3%. Isosorbide dinitrate decreased portal venous inflow 20 +/- 4%, by inducing splanchnic vasoconstriction mediated by low pressure baroreflexes, and this agent also decreased portal pressure, by 14 +/- 2%. Portal venous resistance rose 7.6 +/- 3% with isosorbide dinitrate alone, but decreased 18 +/- 4% with combination therapy. This effect may have been induced by the pronounced vasodilatory effect of isosorbide dinitrate on the venous vasculature, since the reflex splanchnic vasoconstriction that occurs with low-dose isosorbide dinitrate disappears when this agent is combined with SMS 201-995. The decrease in portal pressure was more marked (22 +/- 4%) and changes in systemic hemodynamics were milder with the combined treatment. It was concluded that combination therapy with SMS 201-995 and low-dose isosorbide dinitrate may be beneficial for portal hypertension in liver cirrhosis.

Analysis of Variance↗
PubMed1994

Myocardial protective effect and its mechanism of leukocyte-depleted reperfusion in neonatal rabbit hearts.

Thirty-six isolated blood-perfused hearts from newborn rabbits (age range, birth to 2 days) were subjected to 2 hours of cold global ischemia (15 degrees C), with an initial infusion of cold crystalloid cardioplegic solution, followed by 30 minutes of reperfusion (37 degrees C). The hearts were divided into two groups: those reperfused with whole blood (n = 18) and those reperfused with leukocyte-depleted blood (n = 18) obtained by the passage of blood through a leukocyte removal filter. At 30 minutes of reperfusion, the group of hearts reperfused with leukocyte-depleted blood showed significantly higher percentages of recovery in terms of the left ventricular developed pressure, the maximum rate of increase of left ventricular pressure, the rate pressure product, coronary sinus flow, and the adenosine triphosphate content in myocardium than did the group of hearts reperfused with whole blood. The hearts reperfused with leukocyte-depleted blood also showed significantly lower levels of malondialdehyde, chemiluminescence in the coronary sinus effluent, and counts of intracapillary neutrophils in myocardium than did the group of hearts reperfused with whole blood. The ultrastructural semiquantitative assessment in the myocardium showed that the mitochondrial and endothelial cell damages after 30 minutes of reperfusion were significantly less in the hearts reperfused with leukocyte-depleted blood than those in the hearts reperfused with whole blood.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Purification and characterization of alanine dehydrogenase from a cyanobacterium, Phormidium lapideum.

Alanine dehydrogenase (AlaDH) was purified to homogeneity from cell-free extracts of a non-N2-fixing filamentous cyanobacterium, Phormidium lapideum. The molecular mass of the native enzyme was 240 kDa, and SDS-PAGE revealed a minimum molecular mass of 41 kDa, suggesting a six-subunit structure. The NH2 terminal amino acid residues of the purified AlaDH revealed marked similarity with that of other AlaDHs. The enzyme was highly specific for L-alanine and NAD+, but showed relatively low amino-acceptor specificity. The pH optimum was 8.4 for reductive amination of pyruvate and 9.2 for oxidative deamination of L-alanine. The Km values were 5.0 mM for L-alanine and 0.04 mM for NAD+, 0.33 mM for pyruvate, 60.6 mM for NH4+ (pH 8.7), and 0.02 mM for NADH. Various L-amino acids including alanine, serine, threonine, and aromatic amino acids, inhibited the aminating reaction. The enzyme was inactivated upon incubation with pyridoxal 5'-phosphate (PLP) followed by reduction with sodium borohydride. The copresence of NADH and pyruvate largely protected the enzyme against the inactivation by PLP.

Alanine Dehydrogenase↗