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Biomedical subjects

U Ikeda

Publications and source records attributed to U Ikeda.

At least 199 records · Page 11Linked to original sources

Involvement of adhesion molecules in human monocyte adhesion to and transmigration through endothelial cells in vitro.

Although the accumulation of monocyte-derived foam cells in the subendothelium is a key step in early atherogenesis, the mechanism responsible for monocyte adhesion to and subsequent transmigration through endothelial cells (ECs) has not been defined fully. We investigated the kinetics and the role played by adhesion molecules in the adhesion and transmigration of human monocytes using an in vitro three-dimensional model system comprising ECs cultured on collagen gels. Monocyte adhesion to untreated EC layers increased with time, reached a maximum after 3 h, and then declined. Monocyte transmigration through untreated EC layers also increased with time and reached a plateau after 3-4 h. Prestimulation of ECs with interleukin-1 beta (IL-1 beta; 25 U/ml) for 4 h enhanced monocyte adhesion (40.7 +/- 1.4%) and transmigration (37.9 +/- 1.6%) significantly compared with the value for untreated EC layers. In unstimulated EC layers, anti-leukocyte function-associated antigen-1 (LFA-1) plus anti-intercellular adhesion molecule-1 (ICAM-1) monoclonal antibodies (mAbs) inhibited monocyte adhesion and transmigration significantly by 19% and 20%, respectively, whereas anti-very late antigen-4 (VLA-4) plus anti-vascular cell adhesion molecule-1 (VCAM-1) mAbs did not. In IL-1 beta-stimulated EC layers, anti-LFA 1 plus anti-ICAM-1 mAbs inhibited the adhesion and transmigration by 32% and 30%, respectively and anti-VLA-4 plus anti-VCAM-1 mAbs did so by 18% and 27%, respectively. These results suggest that the monocyte-EC interaction in unstimulated ECs is mediated, in part, by the LFA-1-ICAM-1 pathway and in IL-1 beta-stimulated ECs, in part, by both LFA-1-ICAM-1 and VLA-4-VCAM-1 pathways.

Antibodies, Monoclonal↗

Nitric oxide synthesis in rat cardiac myocytes and fibroblasts.

We investigated nitric oxide (NO) synthase activity in cultured neonatal rat cardiac myocytes and fibroblasts upon treatment with interleukin 1 beta (IL-1 beta) and lipopolysaccharide (LPS). Incubation of cardiac myocytes for 24 h with IL-1 beta or LPS caused a significant increase in NO and cGMP production. Simultaneous incubation of IL-1 beta with NG-monomethyl-L-arginine or transforming growth factor beta (TGF-beta) completely inhibited the IL-1 beta-induced NO and cGMP production in cardiac myocytes. In contrast, incubation of cardiac fibroblasts for 24 h with IL-1 beta or LPS showed no significant effect on NO or cGMP production. Addition of IL-1 beta decreased the beating rate of cardiac myocytes, but TGF-beta overcame that inhibition. These observations suggest the presence of iNOS in cardiac myocytes, which is an important regulator of contractile function of the heart.

Amino Acid Oxidoreductases↗

Decreased Na,K-ATPase gene expression in cardiomyopathic hamster hearts.

We studied Na,K-ATPase mRNA expression in cardiomyopathic (Bio 14.6) and normal (F1b) Syrian hamster ventricles. In Northern blot analysis, Na,K-ATPase alpha 1, alpha 2, alpha 3 and beta 1 isoform mRNAs were detected in 3-week-old Bio 14.6 and F1b hamster ventricles. We then investigated the expression of alpha 1 subunit mRNA in Bio 14.6 hamster ventricles at the ages of 3 weeks prehypertrophic and 30 weeks hypertrophic, and in age-matched F1b hamster ventricles. The alpha 1 subunit mRNA levels in Bio 14.6 hamster ventricles were approximately 50% lower than those in F1b hamster ventricles at both 3 and 30 weeks of age. Na,K-ATPase activity measured in membrane fractions from the ventricles of 3-week-old Bio 14.6 hamsters was also approximately 20% lower than that of F1b hamsters, suggesting that the differences in the mRNA level were associated with the differences in the protein level. We conclude that Na,K-ATPase mRNA expression and enzyme activity are significantly decreased in the hearts of Bio 14.6 hamsters even before the onset of hypertrophy and cardiomyopathy, suggesting that the altered expression of Na,K-ATPase gene is an early event in the pathogenesis of cardiomyopathy in this animal model.

Animals↗

Interleukin 6 gene transcripts are expressed in human atherosclerotic lesions.

Factors controlling the proliferation of vascular smooth muscle cells (SMC) are thought to be key elements in the progression of atherosclerosis. We have previously shown that interleukin 6 (IL-6) stimulates the growth of SMC in vitro and that IL-6 gene transcripts are expressed in atherosclerotic lesions of genetically hyperlipidemic rabbits. To understand the involvement of IL-6 in the development of human atherosclerosis, we investigated IL-6 mRNA expression in atherosclerotic arteries from patients undergoing surgical vascularization, utilizing reverse transcription polymerase chain reaction (RT-PCR) and in situ hybridization analyses. In RT-PCR analysis, the atherosclerotic arteries showed 10- to 40-fold levels of IL-6 mRNA expression over the non-atherosclerotic artery. In in situ hybridization analysis, IL-6 gene transcripts were observed in the thickened intimal layer of atherosclerotic lesions. These results strongly suggest the involvement of IL-6 in the development of human atherosclerosis.

Actins↗

Nitric oxide synthesis in rat mesangial cells induced by cytokines.

The production of nitric oxide (NO) is increased in experimental nephritis, with NO thought to be an important mediator of cell damage. The cytokines interleukin 1 beta (IL-1 beta), IL-6, IL-8, monocyte chemotactic protein-1 (MCP-1) and transforming growth factor-beta (TGF-beta) are released from mesangial cells in vitro or are expressed in various forms of glomerulonephritis. We investigated the effects of these cytokines on NO synthesis in cultured rat mesangial cells. Incubation of mesangial cells with IL-1 beta (10 ng/ml) for 24 h increased the accumulation of NO and guanosine 3',5'-cyclic monophosphate (cGMP). IL-6, IL-8, MCP-1 and TGF-beta showed no significant effect on the production of NO or cGMP. Transcripts of the inducible NO synthase (iNOS) gene were not detected in unstimulated mesangial cells. However, exposure of cells to IL-1 beta (10 ng/ml) for 24 h resulted in the appearance of iNos mRNA. IL-1 beta-induced NO synthesis was significantly inhibited by NG-monomethyl-L-arginine, cycloheximide, actinomycin D, dexamethasone, and TGF-beta. These results indicate that, of the various cytokines studied, only IL-1 beta stimulates iNOS mRNA accumulation and NO synthesis in mesangial cells. NO may function in an autocrine manner to modulate the glomerular response to inflammation.

1-Methyl-3-isobutylxanthine↗

Sodium ion mediated regulation of Na/K-ATPase gene expression in vascular smooth muscle cells.

OBJECTIVE: Na/K-ATPase (Na,K pump) plays an important role in the regulation of intracellular ion composition. The purpose of this study is to determine whether Na+ regulates the levels of mRNA coding for Na/K-ATPase alpha and beta isoforms in cultured rat vascular smooth muscles cells. METHODS: Na/K-ATPase alpha and beta isoform mRNA expression was evaluated by northern blot analysis. The alpha 1 subunit content was determined by ELISA. A luciferase reporter gene assay was performed to study whether the alpha 1 promoter might contain Na+ responsive elements. RESULTS: Na/K-ATPase alpha 1 and beta 1 isoform mRNAs, but not alpha 2 and alpha 3 isoform mRNAs, were expressed in cultured rat vascular smooth muscle cells. Exposure of the cells to 10 microM veratridine, an Na+ channel activator, resulted in two- and threefold increases in alpha 1 and beta 1 mRNA accumulation, respectively, with a maximum at 60 min. The veratridine induced alpha 1 and beta 1 mRNA accumulation was still observed even in the absence of extracellular Ca2+. The increase in alpha 1 mRNA accumulation caused by 10 microM veratridine was associated with a significant increase in alpha 1 subunit protein accumulation. Transfection experiments with chimeric plasmids containing 5'-flanking sequences of alpha 1 isoform gene and luciferase reporter gene showed that 10 microM veratridine caused a threefold increase in luciferase activity. CONCLUSIONS: These results suggest that Na+ stimulates the transcription of Na/K-ATPase alpha 1 and beta 1 isoform genes in vascular smooth muscle cells. The transfection study further supports the premise that Na+ responsive elements are located within the 5'-flanking sequences of alpha 1 isoform gene.

Animals↗

Expression of intercellular adhesion molecule-1 on rat cardiac myocytes by monocyte chemoattractant protein-1.

OBJECTIVE: Cytokine induction of intercellular adhesion molecule-1 (ICAM-1) on cardiac myocytes may be a critical step in cardiac inflammation associated with acute myocardial infarction and myocarditis. The aim of this study was to investigate the involvement of monocyte chemoattractant protein-1 (MCP-1), a homologue of mouse JE, in the neutrophil-myocyte adhesion in vitro. METHODS: MCP-1/JE and ICAM-1 mRNA expression in cultured neonatal rat cardiac myocytes was evaluated by northern blot analysis. ICAM-1 molecule content on myocytes was determined by ELISA. For adherence assay, myocytes and neutrophils were co-incubated and the number of bounded neutrophils was counted. RESULTS: MCP-1/JE transcripts were not clearly observed in cultured neonatal rat cardiac myocytes; however, its transcripts were clearly detected by exposure to interleukin 1 alpha (100 U.ml-1), lipopolysaccharide (1 microgram.ml-1), or hypoxia (95% N2 + 5% CO2). In ELISA analysis, the expression of ICAM-1 molecules on cardiac myocytes was significantly stimulated by MCP-1 in a dose dependent manner, and the effect of MCP-1 was observed as early as at 6 h. In northern blot analysis, ICAM-1 mRNA expression was constitutively observed in myocytes, and the expression was markedly stimulated by exposure to MCP-1 with a peak elevation at 2 h. In adherence assay, MCP-1 stimulated the adhesion of rat neutrophils to rat cardiac myocytes, and this effect of MCP-1 was inhibited by an anti-ICAM-1 MAb. CONCLUSIONS: These results suggest that cardiac myocytes produce MCP-1, which could in turn promote the adhesion of neutrophils to myocytes via ICAM-1 expression, suggesting the involvement of MCP-1 in cardiac inflammation associated with acute myocardial infarction and myocarditis.

Animals↗

Neutrophil adherence to rat cardiac myocyte by proinflammatory cytokines.

Cytokine induction of intercellular adhesion molecule-1 (ICAM-1) in cardiac myocytes may be a critical step in inflammation associated with ischemia-reperfusion injury. We investigated the involvement of tumor necrosis factor-alpha (TNF-alpha), interleukin 6 (IL-6), and interleukin 8 (IL-8) on neutrophil-myocyte adhesion; These cytokines are increased in plasma of patients with acute myocardial infarction (AMI). ICAM-1 expression on cultured neonatal rat cardiac myocytes was determined through immunohistochemical and enzyme-linked immunosorbent assay (ELISA) analysis. ICAM-1 mRNA expression in myocytes was investigated by Northern blot hybridization. Rat neutrophils isolated from peripheral blood (PB) were used for adherence assay. In immunohistochemical study, cultured neonatal rat cardiac myocytes constitutively expressed ICAM-1 molecules. In ELISA analysis, ICAM-1 molecule expression on myocytes was significantly stimulated by TNF-alpha (100 U/ml), but not by IL-6 (100 U/ml) or IL-8 (100 ng/ml) dose dependently. The effect of TNF-alpha was observed as early as 6 h after stimulation. Levels of ICAM-1 mRNA were very low or almost undetectable in unstimulated myocytes, but its expression was markedly induced after exposure to TNF-alpha for 3 h. IL-6 and IL-8 showed no effect on ICAM-1 mRNA accumulation. Adhesion of rat neutrophils to myocytes was stimulated by TNF-alpha, and the effect of TNF-alpha on adherence was significantly inhibited by an anti-ICAM-1 monoclonal antibody (MoAb). These results show that TNF-alpha, but not IL-6 and IL-8, promotes neutrophil-myocyte adhesion through ICAM-1 expression, suggesting involvement of TNF-alpha in inflammation associated with ischemia-reperfusion injury.

Animals↗

Inhibitory effect of interleukin-6 on vascular smooth muscle contraction.

Our objective was to investigate the direct effect of interleukin-6 (IL-6) on the vascular smooth muscle contraction. We measured the contraction of endothelium-denuded aortic rings isolated from Sprague-Dawley rats. We also investigated the involvement of vasodilator prostaglandin and guanosine 3',5'-cyclic monophosphate (cGMP) productions in the effect of IL-6 using cultured rat vascular smooth muscle cells (VSMC). Exposing the aortic rings to recombinant murine IL-6 (50 U/ml) for 180 min significantly suppressed the phenylephrine (10(-9)-10(-5) M)-induced contraction. This inhibitory effect of IL-6 on the contraction tended to exhibit a dose-dependent relationship (0.5-50 U/ml). The effect of IL-6 was totally eliminated in the presence of indomethacin (10(-5) M). The release of immunoreactive 6-ketoprostaglandin F1 alpha from cultured rat VSMC was significantly increased by exposure to IL-6. Intracellular cGMP concentration in VSMC was not affected by IL-6. In conclusion, IL-6 is a potent inhibitor of the alpha-adrenergic-stimulated contraction of vascular smooth muscle. Its action is endothelium independent and mediated by the increased synthesis of prostacyclin in VSMC.

Animals↗

Regulation of Na-K-ATPase gene expression by angiotensin II in vascular smooth muscle cells.

Na-K-adenosinetriphosphatase (Na-K-ATPase) activity profoundly influences vascular cell excitability, contractility, and volume regulation. We investigated the effect of angiotensin II on Na-K-ATPase gene expression in cultured rat vascular smooth muscle cells (VSMC). Na-K-ATPase alpha 1- and beta 1-isoform mRNAs, but not alpha 2- and alpha 3-isoform mRNAs, were expressed in cultured rat VSMC. Angiotensin II (1 microgram/ml) caused a threefold increase in alpha 1-mRNA accumulation and a fourfold increase in beta 1-mRNA accumulation; the peak increases for both alpha 1- and beta 1-mRNA were observed at 6 h. Angiotensin II induced alpha 1- and beta 1-mRNA expression in a dose-dependent manner. Pretreatment of VSMC with cycloheximide (20 micrograms/ml) or actinomycin D (5 micrograms/ml) completely inhibited angiotensin II-induced alpha 1-mRNA accumulation. Even after protein kinase C (PKC) activity was functionally depleted by treating VSMC with phorbol 12-myristate 13-acetate (10(-6) M) for 24 h, angiotensin II increased alpha 1-mRNA accumulation. The angiotensin II-induced increase in alpha 1-mRNA accumulation was associated with an increase in alpha 1-subunit protein accumulation. These results indicate that angiotensin II stimulates Na-K-ATPase alpha 1- and beta 1-isoform gene expression in VSMC and that the effect is mediated not via activation of PKC but needs synthesis of intermediate regulatory protein(s).

Angiotensin II↗

Rare association of congenital bicuspid aortic valve, annuloaortic ectasia, and anomalous origin of left circumflex coronary artery.

A bicuspid aortic valve (BAV) is one of the most common congenital heart anomalies. Although each annuloaortic ectasia (AAE) and malformation of the left coronary artery has been described as a complication of BAV, no case associated with both abnormalities has been reported previously. We present here a very rare case of congenital BAV complicated by AAE and the anomalous origin of the left coronary artery.

Aorta, Thoracic↗

Irreversible cardiomyopathy due to thyrotoxicosis.

We report 4 adult patients with thyrotoxicosis accompanied by irreversible low-output heart failure. Each patient showed elevated plasma levels of thyroid hormone and prolonged low-output heart failure even after thyroid function returned to normal. Specimens of the right ventricular myocardium stained with anti-beta myosin heavy-chain MAb showed a normal staining pattern with a predominance of the beta-form. Our observations suggest that thyrotoxicosis may be one possible cause of irreversible cardiomyopathy.

Aged↗

Endothelin production in pulmonary circulation of patients with mitral stenosis.

BACKGROUND: Although plasma endothelin concentrations are elevated in patients with pulmonary hypertension, the precise sites of endothelin production have not been defined. We investigated the endothelin production in the pulmonary circulation of patients with mitral stenosis and its effects on pulmonary vascular tone. METHODS AND RESULTS: We measured plasma concentrations of endothelin-1, angiotensin II, and thrombomodulin in blood samples obtained from the right and left atria of 10 consecutive patients with rheumatic mitral stenosis (mean age, 55 years; range, 39 to 68) who were undergoing percutaneous mitral valvuloplasty. Plasma levels of endothelin-1 were significantly higher in the left atrium than in the right atrium (3.25 +/- 0.45 versus 2.53 +/- 0.36 pg/mL, mean +/- SE, P < .001). The increased plasma endothelin-1 level in the left atrium, which reflected endothelin-1 production in the pulmonary circulation, was correlated with mean pulmonary artery pressure (r = .65, P = .04), mean pulmonary arterial wedge pressure (r = .67, P = .03), total pulmonary resistance (r = .68, P = .03), and 1/mitral valve area (r = .85, P = .002) but not with pulmonary vascular resistance (r = .04, P = .91). There were no significant differences in plasma levels of angiotensin II and thrombomodulin between the right and left atria (angiotensin II, 16.40 +/- 3.08 versus 15.50 +/- 4.85 pg/mL; thrombomodulin, 2.96 +/- 0.34 versus 2.85 +/- 0.37 ng/mL). CONCLUSIONS: Endothelin-1 production is increased in the pulmonary circulation of patients with mitral stenosis in response to increased pulmonary artery pressure but is not directly related to increased pulmonary vascular tone in this disorder.

Angiotensin II↗

Altered levels of erythrocyte calcium-binding proteins in essential hypertensives with genetic predisposition: correlation with ambulatory blood pressure.

OBJECTIVE: To examine whether changes in calcium-binding proteins, one of the components of the calcium ion handling mechanism, occur in humans with essential hypertension. DESIGN: We measured the levels of cytosolic calcium-binding proteins purified from human erythrocytes using a felodipine fluorescence assay, and examined the correlation between this parameter and the ambulatory blood pressure (ABP). We divided 127 subjects into four age-matched groups according to their mean ABP levels and whether they had a family history of both hypertension and stroke [group A hypertensives with a positive family history (n = 30), group B hypertensives with no family history (n = 31), group C normotensives with a family history (n = 31) and group D normotensives with no family history (n = 35) of hypertension and stroke]. RESULTS: The erythrocyte cytosolic level of calcium-binding proteins in group A was significantly lower than that in group B, as was that in group C compared with group D. There was no significant correlation between the erythrocyte level of calcium-binding proteins and casual blood pressure values in any group. However, in group A significant negative correlations between the erythrocyte level of calcium-binding proteins and systolic and mean ABP were observed (r = -0.34, P < 0.05 and r = -0.39, P < 0.05, respectively). No significant correlations between the ABP and erythrocyte levels of calcium-binding proteins were observed in the other groups. When each group was subdivided according to sex, there were significant negative correlations between the erythrocyte level of calcium-binding proteins and the systolic and mean ABP in the males of groups A and C, but no correlations were found in any of the female subgroups or the males of groups B and D. Reducing the blood pressure by antihypertensive drug therapy did not affect the erythrocyte calcium-binding proteins level in 13 patients from groups A and B. Analysis using anion-exchange fast-performance liquid chromatography on a Mono-Q column and sodium dodecyl sulphate-polyacrylamide gel electrophoresis revealed that the calcium-binding proteins in human erythrocytes, the levels of which were low in group A, formed a single protein band with a molecular weight of 17,000, which was assumed to be a calmodulin. CONCLUSIONS: These results suggest that there are subgroups of hypertensive patients with low erythrocyte cytosolic levels of calcium-binding proteins, which are genetically determined. Furthermore, our data suggest that the erythrocyte level of calcium-binding proteins and ABP in male subjects with hypertension and normotensives with a genetic predisposition are correlated strongly, whereas no such correlation was observed in any female subgroup. This indicates that the regulatory mechanism or mechanisms involved in the control of blood pressure in men and women may be different.

Aging↗

Rapidly growing mural thrombus in an abdominal aortic aneurysm.

While mural thrombus accompanied by an abdominal aortic aneurysm (AAA) is not rare, the growth rate of such a thrombus has not yet been adequately documented. We present here a very rare case of a 62-year-old female patient with an AAA in whom the mural thrombus in the aneurysm grew very rapidly over a short period. We could follow the growth of the mural thrombus in the AAA by two-dimensional (2-D) abdominal echography. Patients with an AAA must be closely monitored by this technique which is able to detect the presence of the thrombus and allow evaluation of its growth.

Aorta, Abdominal↗