Biomedical subjects

Akira Kawamura

Publications and source records attributed to Akira Kawamura.

At least 19 recordsLinked to original sources

PubMed2006

Newly developed reconstituted high-density lipoprotein containing sphingosine-1-phosphate induces endothelial tube formation.

Reconstituted high-density lipoprotein (rHDL) has been shown to produce a rapid regression of atherosclerosis in animal models and humans. Sphingosine-1-phosphate (S1P), which is a bioactive lipid in HDL, plays a role in mitogenesis, endothelial cell motility, and cell survival, as well as organization and differentiation into a vessel. In this study, we examined the direct role of a newly developed rHDL, [POPC(1-palmitoyl-2-oleoyl phosphatidylcholine)/S1P/apolipoproteinA-I(A-I)]rHDL containing S1P in tube formation in endothelial cells (ECs) as well as cholesterol efflux in macrophage. The effect of (POPC/S1P/A-I)rHDL on cholesterol efflux in macrophage was similar to that of conventional rHDL, (POPC/A-I)rHDL. In addition, (POPC/S1P/A-I)rHDL induced EC proliferation through the activation of phospho-Akt and phospho-extracellular-signal-regulated kinases (p-ERK) 1/2 and EC tube formation, and this effect was blocked by inhibitors of Akt, ERK and endothelial nitric-oxide synthase (eNOS). In addition, (POPC/S1P/A-I)rHDL-induced p-ERK1/2 activation and EC tube formation can be mainly attributed to S1P-stimulated signaling through S1P2 and S1P3 as determined by an anti-sense strategy. In conclusion, (POPC/S1P/A-I)rHDL induces cholesterol efflux independently of S1P but has additional S1P-mediated effects on EC tube formation mediated by Akt/ERK/NO through S1P2 and S1P3. In the future, these new discs may be useful for the treatment of atherosclerotic and ischemic cardiovascular disease, such as acute coronary syndrome and atherosclerosis obliterans.

Animals↗

PubMed2006

Lower level of low-density lipoprotein cholesterol by statin prevents progression of coronary restenosis after successful stenting in acute myocardial infarction.

OBJECTIVE: It is unclear whether the reduction of coronary restenosis by statins is due to a decrease in low-density lipoprotein (LDL) cholesterol and/or pleiotropic effects. Therefore, we performed quantitative coronary angiography (QCA) and analyzed the lipid profile and changes in adhesion molecules and chemokines caused by statin in patients with acute myocardial infarction (AMI). METHODS: The subjects included AMI patients who had initial coronary angiograms and significant coronary stenosis and were implanted with a stent. After stent implantation, patients were treated either with (n = 36) or without (n = 14) statin. The primary end-point for this study was the absolute changes in the lipid profile, C-reactive protein (CRP), adhesion molecules, chemokines and stenosis measured by QCA between the post-stent and follow-up angiogram at 6 months after stenting. RESULTS: Treatment with statin reduced % coronary diameter stenosis (DS) and was associated with a greater reduction in LDL cholesterol at 6 months after stenting in patients with acute myocardial infarction (AMI), while there were no differences in adhesion molecules, chemokines, CC chemokine receptor or CXC chemokine receptor. Interestingly, changes in % DS between before and after statin treatment at 6 months (Delta%DS) were positively correlated with DeltaLDL cholesterol, and patients who had an LDL cholesterol level of less than 80 mg/dl had a significantly lower Delta%DS. In addition, Delta%DS was significantly related only to the reduction in LDL cholesterol as assessed by a stepwise multivariable regression analysis. CONCLUSION: These results suggest that the lower level of LDL cholesterol is the most critical factor in preventing coronary restenosis.

Aged↗

PubMed2006

Selective photolabeling of Lck kinase in complex proteome.

A molecular probe that selectively tags Lck, a Src-family kinase, was developed. This probe was one of many compounds originally designed to target the active site of tyrosine kinases in general. To our surprise, however, the probe almost exclusively labeled Lck even in a lysate of Jurkat cells. This finding led us to further characterize this probe-Lck complex by a series of photolabeling and mass spectrometric analyses. The probe-binding site on Lck was located within the well-conserved region of Src-family kinases, as we originally expected. However, the unexpected selectivity of this probe toward Lck suggests that subtle factors, which are difficult to predict based on static crystal structures, play important roles in probe recognition.

Amino Acid Sequence↗

PubMed2006

Rediscovery of natural products using genomic tools.

A screening methodology called 'genomic screening' was established to identify natural products that can regulate cellular gene expression. Application of genomic screening to Keishi-bukuryo-gan (KBG), a Japanese herbal medicine formulation, identified a previously unnoticed transcriptional effect by linoleic acid, a known KBG component. The approach opens up a possibility to develop cell-permeable molecular tools for functional genomics research and sets a stage to evaluate the potential of natural products for transcription therapies.

Biological Products↗

PubMed2006

Gene expression profiling of intrinsic thermotolerance in Escherichia coli.

DNA microarrays were employed to compare gene expression in a thermotolerant, nalidixic acid-resistant mutant of Escherichia coli with that of the parental strain. When grown at 37 degrees C, up-regulated genes in the mutant included those coding for multiple antibiotic resistance proteins and enzymes for the degradation of small molecules, whereas among the down-regulated genes were those coding for fimbrial, flagellar, and outer membrane proteins as well as sigma 38. When the mutant grown at 42 degrees C was compared to the mutant grown at 37 degrees C, enhanced expression of several genes coding for flagellar proteins was detected. Reverse transcriptase-polymerase chain reaction analysis of selected genes confirmed results obtained with microarrays.

Adaptation, Physiological↗

PubMed2006

Clinical significance of the coronary calcification score by multidetector row computed tomography for the evaluation of coronary stenosis in Japanese patients.

BACKGROUND: The coronary artery calcification (CAC) score measured by multidetector row computed tomography (MDCT) has emerged as a marker for predicting coronary artery disease (CAD). To evaluate the clinical significance of the CAC score, coronary artery stenosis as assessed by coronary angiography (CAG) was compared with the CAC score determined by MDCT, risk factors and medications. METHODS AND RESULTS: Subjects included 374 consecutive patients who underwent ECG-gate CT angiography using MDCT. The accuracy in patients with a CAC score >or=400 was 84%, and significantly lower than that in patients with a CAC score =0. In addition 92 patients (68 males, 24 females; mean age, 63+/-11 years) who underwent both MDCT and CAG within a 1-month period were selected for further investigation. Patients with significant coronary stenosis had a significantly higher CAC score than those without stenosis. In addition, a higher number of stenosed vessels was associated with a higher CAC score. The subjects were divided into 3 groups according to the CAC score: low (0-12), intermediate (13-444) and high (>or=445). The CAC score was significantly associated with age, and plasma levels of total cholesterol and hemoglobinA1c, and logistic regression analysis revealed that significant coronary stenosis as assessed by CAG was most closely correlated with the CAC score (p=0.03). CONCLUSIONS: The CAC score determined by MDCT can predict CAD independent of other factors, such as age, metabolic diseases and medications, when coronary stenosis can not be diagnosed because of severe calcification.

Aged↗

PubMed2006

Angiotensin II type 1 receptor blockers do not promote coronary collateral circulation in patients with coronary artery disease.

We previously reported that angiotensin-converting enzyme inhibitors (ACE-Is) promote collateral circulation in patients with coronary artery disease (CAD). There have been many reports on the beneficial effects of angiotensin II type 1 receptor blockers (ARBs) on the cardiac microvasculature. Therefore, the following studies were performed to evaluate the association between treatment with an ARB and the enhancement of coronary collateral circulation as assessed by the Rentrop Score (RS) (Study 1) and to compare these results to those obtained with an ACE-I (Study 2). The subjects were 456 patients with angina who underwent coronary angiography. Study 1: Those who had one (1-V), two (2-V) or three significantly stenosed vessels (3-V) and who received only an ARB without any other anti-hypertensive medication were defined as the ARB group (n=81), and age-, sex- and body mass index-matched subjects (n=146) were selected as a comparative group. There were no significant differences in the percentage of patients with RS>or=1 between the two groups. Study 2: Those who received an ACE-I as the only anti-hypertensive treatment were defined as the ACE-I group (n=67), which was matched to the ARB group in Study 1. The percentage of patients with RS>or=1 in the ACE-I group was significantly higher than that in the ARB group as assessed by a Cochran-Mantel-Haenszel analysis. In addition, patients with 3-V disease who were treated with an ACE-I, but not an ARB, were most likely (odds ratio [confidence Interval]): 27.7 [4.8-161.0]) to show enhanced collateral circulation, as assessed by a multiple logistic regression analysis. These results suggest that treatment with an ACE-I, but not treatment with an ARB, was associated with the enhancement of collateral circulation in patients with CAD.

Aged↗

PubMed2006

Significance of combined angiotensin II receptor blocker and carvedilol therapy in patients with congestive heart failure and arginine variant.

OBJECTIVE: Angiotensin II receptor blockers (ARBs) and beta-blockers have contributed to longer life expectancies for patients with congestive heart failure. However, whether the use of ARBs is helpful for introducing carvedilol (beta-blocker) is unclear when patients with symptomatic congestive heart failure are admitted to the hospital. METHODS: In this retrospective study, 27 patients with symptomatic congestive heart failure were given carvedilol upon admission. Five patients received carvedilol monotherapy (group A), and 22 were treated with a combination of carvedilol and ARBs (group B). RESULTS: There was no difference in medication between the groups except for ARBs. In addition, there were no significant differences in the decrease in plasma brain natriuretic peptide, or the improvement of left ventricular ejection fraction upon carvedilol treatment between the groups. Although there was no significant difference in the maintenance dose of carvedilol between the groups, the gross dose of carvedilol in group B was significantly lower than that in group A. In addition, the improvement of left ventricular ejection fraction in group B was positively correlated with the maintenance dose of carvedilol in patients who had wild-type beta1-adrenergic receptor at amino acid 389 (arginine/arginine genotype). CONCLUSIONS: These results suggest that ARBs are helpful for introducing carvedilol in patients with the wild-type beta1-adrenergic receptor gene, and that treatment with combined treatment with ARB or analysis of the beta1-adrenergic receptor genotype may offer advantages to control congestive heart failure in the short-term.

Adrenergic beta-Antagonists↗

PubMed2005

Pitavastatin-induced downregulation of CCR2 and CCR5 in monocytes is associated with the arrest of cell-cycle in S phase.

The pleiotropic effects of statin, including its anti-inflammatory effects, via chemokines may be independent of statin-induced cholesterol reduction. Therefore, we examined the effect of pitavastatin on cell proliferation and the association between chemokine receptors (CCR2 and CCR5) and their ligands, RANTES (regulated upon activation, normal T cell-expressed and secreted) and monocyte chemotactic protein-1 (MCP-1), in monocytes. Pitavastatin but not pravastatin inhibited cell proliferation in a dose-dependent manner and showed S-phase arrest associated with the downregulation of CCR2 and CCR5 expression in human monocytic tumor cells (U937 cells). Although the anti-proliferative effects of pitavastatin were not inhibited by lower concentrations of RANTES and MCP-1, overexpression of CCR2/CCR5 significantly blocked the anti-proliferation with a low concentration of RANTES or MCP-1. Pitavastatin upregulated p21(waf1) but not p27(kip1), and did not change the expression levels of cyclin D1 or cdk4. In addition, RANTES and MCP-1 upregulated cyclin D1 in the presence of pitavastatin. In conclusion, the anti-proliferative effect of pitavastatin, but not pravastatin, through the downregulation of CCR2/CCR5 may be a pleiotropic effect. This effect may be anti-atherogenic in monocytes.

Anticholesteremic Agents↗

PubMed2005

JTT-705 blocks cell proliferation and angiogenesis through p38 kinase/p27(kip1) and Ras/p21(waf1) pathways.

The excessive proliferation and migration of vascular smooth muscle cells (SMCs) participate in the growth and instability of atherosclerotic plaque. We examined the direct role of a newly developed chemical inhibitor of cholesteryl ester transfer protein, JTT-705, on SMC proliferation and angiogenesis in endothelial cells (ECs). JTT-705 inhibited human coronary artery SMC proliferation. JTT-705 induced the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and extracellular-signal-regulated kinases (ERK) in SMCs. In addition, the anti-proliferative effects of JTT-705 in SMCs were blocked by p38 MAPK inhibitor. JTT-705 induced the upregulation of p-p21(waf1), and this effect was blocked by dominant-negative Ras (N17), but not by inhibitors of p38 MAPK or ERK. In addition, JTT-705 also induced the upregulation of p27(kip1), and this effect was blocked by p38 MAPK inhibitor. Interestingly, culture medium from JTT-705-treated SMCs blocked human coronary artery EC tube formation in an in vitro model of angiogenesis indirectly via a decrease in vascular endothelial growth factor (VEGF) from SMCs and directly via an anti-proliferative effect in ECs. JTT-705 blocked the proliferation of SMCs through the activation of p38 kinase/p27(kip1) and Ras/p21(waf1) pathways, and simultaneously blocked EC tube formation associated with a decrease in VEGF production from SMCs and an anti-proliferative effect in ECs. Our results indicate that JTT-705 may induce a direct anti-atherogenic effect in addition to its inhibitory effect of CETP activity.

Amides↗

PubMed2005

Protein fishing with chiral molecular baits.

Chirality plays a central role in various biological recognition processes. Here a methodology was developed to utilize chiral recognition processes for the selective biotinylation of proteins in crude cell lysates. Two pairs of diastereomeric probes containing benzophenone and biotin were prepared through solid-phase synthesis. Protein-binding selectivity of each probe was examined by photo-cross-linking of cell lysates, followed by SDS-PAGE and Western blot. The study revealed that our approach permits selective labeling of benzophenone-binding proteins in complex proteomes. In addition, it was found that the selectivity depends largely on a single chiral center and substitutions in the vicinity of benzophenone. Taken together, the current work demonstrates that chiral recognition process can be employed to selectively label proteins in complex proteomes. Thus the study opens up the possibility to expand the scope of chemical proteomics research for various applications, including biomarker discovery, drug screening and development.

Biotin↗

PubMed2005

Relationship between masticatory function and internal structure of the mandible based on computed tomography findings.

INTRODUCTION: The purposes of this study were to investigate bone mineral density as a part of bone construction in human skulls and to examine the relationship between dentofacial morphology and masticatory function by using computed tomography (CT) findings. Changes in bone mineral density in the mandible because of loss of masticatory function were tested in rats by experimentally producing an environment that inhibited mastication by the molars. METHODS: Data for the human study were obtained from 27 modern male Japanese skulls (mean age, 28 years) from the University of Tokyo. Cortical bone thickness (CBT) and CT value (CV) were measured by each CT scan of the first and molars. For the animal study, a metal cap was inserted between the maxillary and mandibular incisors to prevent the molars from biting in 6-week-old male Wistar rats. The rats were killed after 2, 4, or 6 weeks, and bone mineral density was measured in cancellous and cortical bone equivalent to the first molar region by using peripheral quantitative computed tomography. RESULTS: In the human skull study, significant negative correlations were observed between CV in the regions of the buccal side of the second molar and the angle between the Frankfort horizontal and mandibular planes. Significant negative correlations were also observed between the gonial angle and CV in the buccal and basal sides. In the animal study, cancellous bone mineral density began to decline 4 weeks after the start of the experiment in the masticatory hypofunction group compared with the control group. By week 6, cancellous bone density had declined by 11.6% on the buccal side, 16.7% on the lingual side, 12.3% at the bifurcation of the root, and 38.1% at the root apex. Cortical bone density declined by 8% to 12% on the lingual side. CONCLUSIONS: The results support our hypothesis that a functional adaptive response by the mandible to mechanical stress resulting from mastication occurs not only in the muscle insertion area, but also in mandibular alveolar bone in the molar region.

Adaptation, Physiological↗

PubMed2005

Effect of statin on restenosis after radius stent implantation in patients with acute coronary syndrome.

Despite reports that statin treatment reduces the rate of coronary restenosis with a balloon expandable stent, there is no evidence that statins affect the incidence of restenosis with a self-expanding Radius stent. Ninety-five patients with acute coronary syndrome who had been implanted with a Radius stent were classified into two groups: those with hyperlipidemia and initial statin treatment (statin group, n = 38) and those without statin treatment (comparative group, n = 57). At six months after stent implantation, the rate of coronary restenosis was significantly lower in the statin group (10.5%) than control group (28.1%) (p = 0.033), while there were no differences in morphology, maximal inflation pressure or stent size between the two groups. Interestingly, there was no difference in the serum lipid profile between the two groups at the 6-month follow-up, although the statin group had a significantly lower rate of restenosis. In conclusion, initial statin therapy reduced the rate of coronary restenosis even when a Radius stent was implanted.

Acute Disease↗

PubMed2004

Increased expression of monocyte CD11a and intracellular adhesion molecule-1 in patients with initial atherosclerotic coronary stenosis.

BACKGROUND: Cell adhesion molecules have been implicated in the adhesion of leukocytes to endothelial cells and therefore play a role in atherosclerosis, which is a frequent cause of morbidity and mortality in patients with coronary artery disease (CAD) or undergoing hemodialysis (HD). The levels of expression of leukocyte adhesion molecules were evaluated in patients with CAD or HD. METHODS AND RESULTS: The expression of leukocyte (ie, neutrophil, monocyte and lymphocyte) surface CD11a, CD18, intracellular adhesion molecule-1 (ICAM-1), very late antigen-4 alpha (VLA-4 alpha) and L-selectin was investigated by flow cytometry in 20 patients who were initially diagnosed with CAD (CAD group), 15 patients with coronary re-stenosed vessels (RESTE group), 20 undergoing HD (HD group) and 20 without CAD (CONT group). Monocyte surface expression of both CD11a and ICAM-1 in the CAD group was significantly higher than in the CONT group. Interestingly, when 15 patients with RESTE were analyzed, they showed monocyte CD11a and ICAM-1 expression levels comparable to those in the CONT group. On the other hand, there were no significant differences in the expression of CD11a, CD18, L-selectin or VLA-4 alpha between the HD group and CONT group, but monocyte L-selectin was increased in the CAD group compared with the CONT group. CONCLUSIONS: Because CD11a and CD18 are expressed on the cell surface as a heterodimer and ICAM-1 is a ligand for CD11a/CD18, this increased expression of CD11a and ICAM-1 may affect the development of initial atherosclerotic coronary stenosis, but not re-stenosis.

Aged↗

PubMed2004

Changes in the expression of leukocyte adhesion molecules throughout the acute phase of myocardial infarction.

Since increased leukocytes within days after the onset of acute myocardial infarction (AMI) may reflect an increased expression of the adhesion molecules necessary for effective endothelial transmigration, we evaluated the expression of adhesion molecules on leukocytes throughout the acute phase of MI. We measured the number of leukocytes and enzymes and the expression levels of CD11a, CD18, very-late-after-activation antigen-4 alpha, intracellular adhesion molecule-1 (ICAM-1) and L-selectin by flow cytometry before and after coronary intervention, and at 6, 12, 18, 48 and 72 hours of MI in 5 patients (AMI group). As controls, we measured these parameters in 5 patients who had been diagnosed with angina pectoris and underwent coronary intervention (AP group). In the AMI group the expression of monocyte CD11a was significantly increased after 6 hours, and CD18 and ICAM-1 expression were also significantly increased after 12 hours, whereas that of monocyte L-selectin was increased after 72 hours. In addition, the increased monocyte CD11a was accompanied by an increased number of monocytes and a greater expression of CD11a per cell in the AMI group. In conclusion, since CD11a and CD18 are expressed on the cell surface as a heterodimer and ICAM-1 is a ligand for CD11a/CD18, their increased expression may contribute to their adhesion to endothelium in ischemic regions and may lead to the formation of microaggregates.

Acute-Phase Proteins↗

PubMed2003

Ras/Raf1-dependent signal in sphingosine-1-phosphate-induced tube formation in human coronary artery endothelial cells.

Since we recently reported that high density lipoprotein, which contains the bioactive lipid sphingosine-1-phosphate (S1P) [Arterioscler. Thromb. Vasc. Biol. 23 (2003) 802], induced human coronary artery endothelial cell (HCEC) tube formation mediated by a Ras/Raf/ERK (extracellular signal-activated kinase) pathway, we thought that it would be very important to evaluate whether the signal in S1P-induced tube formation is Ras-dependent or -independent. In an in vitro model of HCEC tube formation on a matrix gel, S1P-induced tube formation. ERK1/2 inhibitor (PD98059) and pertussis toxin (PTX) suppressed S1P-induced tube formation. S1P activated phospho(p)-ERK1/2, while dominant-negative RasN17 blocked S1P-induced p-ERK1/2. Moreover, RasN17 inhibited S1P-induced tube formation. S1P activated Ras/Raf1 by Ras pull-down assay and this effect was inhibited by PTX. These results demonstrate that Ras/Raf1-dependent ERK activation mediated by PTX-sensitive G protein-coupled receptors may be a potent signal in S1P-induced HCEC tube formation.

Cells, Cultured↗

PubMed2003

High density lipoprotein-induced angiogenesis requires the activation of Ras/MAP kinase in human coronary artery endothelial cells.

OBJECTIVE: Plasma high density lipoprotein (HDL) levels have been shown to be inversely correlated with coronary artery disease, but the mechanisms of the direct protective effect of HDL on endothelial cells (ECs) are not fully understood. In this study, we investigated the role of the HDL-mediated promotion of angiogenesis in human coronary artery ECs (HCECs). METHODS AND RESULTS: We developed an in vitro model of HCEC tube formation on a matrix gel. We optimized the maximum dose of HDL required to induce tube formation in initial experiments, in which the dose response showed that the maximum effective dose of HDL was 100 microg/mL. PD98059, an inhibitor of p42/44 mitogen-activated protein kinase (MAPK) activity, but not SB203580, an inhibitor of p38 MAPK activity, suppressed HDL-induced tube formation. Dominant-negative Ras N17 inhibited HDL-induced tube formation. HDL activated Ras according to a ras pull-down assay, and this effect was inhibited by pertussis toxin. Moreover, HDL activated phospho(p)-p42/44 MAPK, whereas Ras N17 blocked HDL-induced pp42/44 MAPK. CONCLUSIONS: These results indicate that HDL induced a potent signal through a Ras/MAPK pathway mediated by a pertussis toxin-sensitive G-protein coupled receptor to the angiogenic phenotype in HCECs.

Cells, Cultured↗

PubMed2003

Nocturnal gastric acid breakthrough during the administration of rabeprazole and ranitidine in Helicobacter pylori-negative subjects: effects of different regimens.

BACKGROUND: Nocturnal gastric acid breakthrough (NAB) is defined as nocturnal intragastric pH less than 4 for more than 1 h during proton pump inhibitor (PPI) administration. A bedtime dose of an H2 receptor antagonist (H2RA) inhibites NAB, but the efficacy of the H2RA decreases with continuous administration. We carried out the present study to investigate the effect of 14-day H2RA administration on NAB. METHODS: Ten male volunteers without Helicobacter pylori infection received four different 14-day regimens of rabeprazole and ranitidine (study a, morning dose of 20 mg rabeprazole; study b, morning dose of 20 mg rabeprazole with a single bedtime dose of 150 mg ranitidine only on the last day; study c, continuous 20 mg morning dose of rabeprazole and 150 mg at bedtime; study d, morning and evening doses of 10 mg rabeprazole). Ambulatory 24-h gastric pH monitoring was conducted on the last day of each regimen. RESULTS: NAB in studies a, b, c, and d was observed in 9, 1, 4, and 4 subjects, respectively, and the longest periods of nocturnal gastric pH at less than 4.0 were 102.5, 14.0, 37.5, and 52.5 min, respectively (study b vs study c, P<0.05). CONCLUSIONS: The continuous inhibitory effect of ranitidine combined with rabeprazole on nocturnal gastric acid secretion declined during 14-day-long administration in H. pylori-negative subjects. Split dosing of rabeprazole was more effective than the single morning dose for inhibiting nocturnal gastric acid secretion.

2-Pyridinylmethylsulfinylbenzimidazoles↗