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Biomedical subjects

M Yoshiyama

Publications and source records attributed to M Yoshiyama.

At least 19 recordsLinked to original sources
PubMed2006

Dominant-negative c-Jun inhibits rat cardiac hypertrophy induced by angiotensin II and hypertension.

Cardiac activator protein-1 (AP-1), composed of c-Jun, is significantly activated by hypertension or angiotensin II (AngII). This study was undertaken to elucidate whether c-Jun could be the potential target for treatment of cardiac hypertrophy. We constructed recombinant adenovirus carrying dominant-negative mutant of c-Jun (Ad.DN-c-Jun). Using catheter-based technique of adenoviral gene transfer, we achieved global myocardial transduction of DN-c-Jun in rats, to specifically inhibit cardiac AP-1. (1) AngII (200 ng/kg/min) infusion in rats caused cardiac hypertrophy, increased cardiac p70S6 kinase activity by 1.3-fold (P<0.05) and enhanced the gene expression of cardiac hypertrophic markers. Ad.DN-c-Jun, which was transferred to the heart 2 days before AngII infusion, prevented cardiac hypertrophy (P<0.01), decreased p70S6 kinase phosphorylation (P<0.05), and suppressed cardiac gene expression of brain natriuretic peptide, collagen I, III, and IV, monocyte chemoattractant protein-1 (MCP-1) and plasminogen activator inhibitor-1 (PAI-1) (P<0.01). (2) In genetically hypertensive rats with cardiac hypertrophy, cardiac gene transfer of Ad.DN-c-Jun, without affecting hypertension, regressed cardiac hypertrophy (P<0.05), and suppressed p70S6 kinase phosphorylation by 20% (P<0.05) and suppressed the enhanced expression of collagen I, III, and IV, MCP-1 and PAI-1. These results provided the first evidence that in vivo blockade of cardiac c-Jun inhibits pathologic cardiac hypertrophy.

Adenoviridae↗
PubMed2006

Effects of resin hydrophilicity on dentin bond strength.

The purpose of this study was to determine if hydrophobic resins can be coaxed into dentin wet with ethanol instead of water. The test hypothesis was that dentin wet with ethanol would produce higher bond strengths for hydrophobic resins than would dentin wet with water. This study examined the microtensile bond strength of 5 experimental adhesives (50 wt% ethanol/50% comonomers) of various degrees of hydrophilicity to acid-etched dentin that was left moist with water, moist with ethanol, or air-dried. Following composite buildups, hourglass-shaped slabs were prepared from the bonded teeth for microtensile testing. For all 3 types of dentin surfaces, higher bond strengths were achieved with increased resin hydrophilicity. The lowest bond strengths were obtained on dried dentin, while the highest bond strengths were achieved when dentin was bonded moist with ethanol. Wet-bonding with ethanol achieved higher bond strengths with hydrophobic resins than were possible with water-saturated matrices.

Analysis of Variance↗
PubMed2005

Relation between aortic stiffness and coronary flow reserve in patients with coronary artery disease.

OBJECTIVES: To investigate the relation between aortic stiffness and coronary flow reserve (CFR) in patients with coronary artery disease (CAD). DESIGN: Observational study. SETTING: Coronary care unit of a primary care hospital. PATIENTS: 192 consecutive patients who underwent coronary angiography. MAIN OUTCOME MEASURE: Brachial-ankle pulse wave velocity (ba-PWV), CFR, and severity of CAD. RESULTS: According to the angiographic findings, patients were divided into four subgroups: patients without significant stenosis (normal coronary artery (NCA) group, n = 28) and those with one vessel disease (1VD group, n = 92), two vessel disease (2VD group, n = 50), or three vessel disease (3VD group, n = 22). ba-PWV increased with the number of diseased vessels and was significantly correlated with the number of diseased vessels (NCA group v 1VD group v 2VD group v 3VD group: 1481 (252) v 1505 (278) v 1577 (266) v 1727 (347) cm/s, p < 0.001). CFR had a significant negative correlation with ba-PWV (r = -0.45, p < 0.0001). The diastolic to systolic velocity ratio obtained in 45 patients also was significantly correlated with ba-PWV (r = -0.35, p < 0.05). Multiple regression analysis showed that ba-PWV was an independent determinant of CFR (p < 0.01). CONCLUSIONS: Coronary flow is altered with aortic stiffening in patients with CAD. These results suggest one possible mechanism for recent reports that aortic stiffness is a key cardiovascular risk factor.

Ankle↗
PubMed2005

Microbubble destruction with ultrasound augments neovascularisation by bone marrow cell transplantation in rat hind limb ischaemia.

OBJECTIVE: To examine the effects of microbubble destruction with ultrasound (MB) combined with bone marrow derived mononuclear cell transplantation (BMT) into ischaemic tissues in rat hind limb ischaemia. METHODS AND RESULTS: Unilateral hind limb ischaemia was surgically induced in Lewis rats. At postoperative day 7, rats were randomly divided into three groups: a vehicle treated group, an ultrasound treated group, and an MB treated group. MB treatment increased vascular endothelial growth factor mRNA as assessed by real time polymerase chain reaction (3.0-fold, p < 0.05). At four weeks, the MB group had increases in laser Doppler blood flow index (LDBFI; 1.2-fold, p < 0.05), angiographically detectable collateral vessels (angiographic score: 1.4-fold, p < 0.01), and capillary to muscle fibre ratio (1.4-fold, p < 0.01) in ischaemic limbs compared with the vehicle treated group. No differences were seen between the vehicle and ultrasound treated groups. Secondly, rats were allocated to vehicle treatment, BMT (5 x 10(6) cells/rat), or a combination of MB and BMT (MB+BMT) at seven days after hind limb ischaemia. BMT treatment significantly increased LDBFI, angiographic score, and capillary to muscle fibre ratio compared with vehicle treatment. Interestingly, MB+BMT treatment produced significantly greater LDBFI (1.2-fold, p < 0.01), angiographic score (1.5-fold, p < 0.01), and capillary to muscle fibre ratio (1.5-fold, p < 0.05) than BMT treatment alone. CONCLUSIONS: MB may be a useful technique to enhance BMT induced neovascularisation.

Animals↗
PubMed2005

Effects of eplerenone on transcriptional factors and mRNA expression related to cardiac remodelling after myocardial infarction.

OBJECTIVE: To examine the effects of eplerenone, a selective aldosterone blocker, on cardiac function after myocardial infarction (MI) and myocardial remodelling related transcriptional factors and mRNA expression in non-infarcted myocardium. METHODS: MI was induced by ligation of the coronary artery in Wistar rats. Rats were randomly assigned to a vehicle treated group or an eplerenone treated group (100 mg/kg/day). RESULTS: At four weeks after MI, left ventricular (LV) end diastolic pressure, LV weight, and LV end diastolic dimension were increased in MI rats. Eplerenone significantly reduced the increase in LV end diastolic pressure, LV weight, and LV end diastolic dimension. In the MI rats the decreased ejection fraction indicated systolic dysfunction and the increased E wave to A wave ratio and E deceleration rate indicated diastolic dysfunction. Eplerenone significantly attenuated this systolic and diastolic dysfunction. Myocardial interstitial fibrosis, transcriptional activities of activator protein 1 and nuclear factor kappaB, and mRNA expression of monocyte chemoattractant protein 1, plasminogen activator inhibitor 1, atrial natriuretic peptide, brain natriuretic peptide, and collagen types I and III were significantly increased at four weeks after MI. Eplerenone significantly attenuated interstitial fibrosis and suppressed transcriptional activity and mRNA expression of these genes. CONCLUSIONS: When administered after MI, eplerenone prevents cardiac remodelling accompanied by systolic and diastolic dysfunction and inhibits abnormal myocardial transcriptional activities and gene expression.

Animals↗
PubMed2005

Intravenous myocardial contrast echocardiography predicts regional and global left ventricular remodelling after acute myocardial infarction: comparison with low dose dobutamine stress echocardiography.

OBJECTIVE: To assess the role of intravenous myocardial contrast echocardiography (MCE) in predicting functional recovery and regional or global left ventricular (LV) remodelling after acute myocardial infarction (AMI) compared with low dose dobutamine stress echocardiography (LDSE). METHODS: 21 patients with anterior AMI and successful primary angioplasty underwent MCE and LDSE during the subacute stage (2-4 weeks after AMI). Myocardial perfusion and contractile reserve were assessed in each segment (12 segment model) with MCE and LDSE. The 118 dyssynergic segments in the subacute stage were classified as recovered, unchanged, or remodelled according to wall motion at six months' follow up. Percentage increase in LV end diastolic volume (%DeltaEDV) was also calculated. RESULTS: The presence of perfusion was less accurate than the presence of contractile reserve in predicting regional recovery (55% v 81%, p < 0.0001). However, the absence of perfusion was more accurate than the absence of contractile reserve in predicting regional remodelling (83% v 48%, p < 0.0001). The number of segments without perfusion was an independent predictor of %DeltaEDV, whereas the number of segments without contractile reserve was not. The area under the receiver operating characteristic curve showed that the number of segments without perfusion predicted substantial LV dilatation (%DeltaEDV > 20%) more accurately than did the number of segments without contractile reserve (0.88 v 0.72). CONCLUSION: In successfully revascularised patients with AMI, myocardial perfusion assessed by MCE is predictive of regional and global LV remodelling rather than of functional recovery, whereas contractile reserve assessed by LDSE is predictive of functional recovery rather than of LV remodelling.

Aged↗
PubMed2005

Supraspinal and spinal alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid and N-methyl-D-aspartate glutamatergic control of the micturition reflex in the urethane-anesthetized rat.

Effects of i.c.v. and i.t. administration of (3SR,4aRS,6RS,8aRS)-6-[2-(1H-tetrazol-5-yl)ethyl]decahydroisoquinoline-3-carboxylic acid (LY215490), a competitive alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor antagonist and MK-801, a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist on the micturition reflex were evaluated in urethane-anesthetized rats, to determine if glutamatergic mechanisms in brain as well as spinal cord are important for the control of micturition. I.c.v. or i.t. injection of LY215490 in low doses (0.01-0.03 microg) did not change rhythmic bladder or external urethral sphincter (EUS) electromyogram (EMG) activity during continuous cystometrograms (CMGs; 0.21 ml/min), whereas higher doses (0.1-1 microg) markedly suppressed these responses. During single CMGs (0.04 ml/min), 0.1-1 microg i.c.v. or 0.1-10 microg i.t. doses increased volume threshold and pressure threshold for inducing micturition, and decreased bladder contraction amplitude and voiding efficiency. MK-801 in low doses (0.6 microg i.c.v. or 0.6-1.8 microg for i.t.) did not change bladder contraction amplitude or EUS EMG activity during continuous CMGs, whereas higher doses 6-60 microg markedly suppressed these responses. During single CMGs, MK-801 (6-60 microg i.c.v. or 60 microg i.t.) increased volume threshold and pressure threshold, and decreased voiding efficiency and bladder contraction amplitude. Pretreatment i.c.v. with MK-801 in a dose 1.8 microg which alone had little effect on bladder contraction amplitude and EUS EMG activity, markedly enhanced depressant effects of LY215490 (0.03 microg i.c.v.) on these responses. Administration of same doses of drugs by i.t. route did not elicit a similar synergistic interaction. These data indicate that in urethane-anesthetized rats glutamatergic mechanisms in brain and spinal cord are essential for controlling micturition and that interactions between AMPA and NMDA glutamatergic transmission are important at supraspinal but not spinal sites.

Anesthesia↗
PubMed2005

Antioxidant gene expression in the blood-feeding fly Glossina morsitans morsitans.

We report the characterization of 11 antioxidant genes from the tsetse fly Glossina m. morsitans. Through similarity searches which detected homology we suggest that these genes consist of two superoxide dismutases (one with a putative signal peptide), three thioredoxin peroxidases (one with a putative signal peptide), three peroxiredoxins, one further signal peptide-containing peroxidase with its closest similarity to a glutathione peroxidase, one catalase and one thioredoxin reductase. We describe the changes occurring in the expression levels of these genes during fly development, in different adult tissues, in the adult midgut through the digestive cycle and following trypanosome infection. Overall, nine of the 11 genes studied showed responses to changes in physiological circumstance, with the peroxiredoxin group showing the smallest variations throughout.

Animals↗
PubMed2005

Angiotensin converting enzyme inhibitor prevents left ventricular remodelling after myocardial infarction in angiotensin II type 1 receptor knockout mice.

BACKGROUND: It is well known that angiotensin converting enzyme (ACE) inhibitors and angiotensin II type 1 (AT1) receptor blockers (ARBs) prevent left ventricular (LV) remodelling after myocardial infarction (MI). However, it is still not clear whether inhibition of the AT1 receptor is enough to prevent LV remodelling after MI. OBJECTIVE: To elucidate the effects of ACE inhibitors that are not mediated by the AT1 receptor on LV remodelling, MI was experimentally induced in wild-type (WT-MI) mice and AT1 receptor knockout (KO-MI) mice. METHODS: Mice were divided into six groups: WT-control, KO-control, WT-MI, KO-MI, WT-MI treated with an ACE inhibitor, and KO-MI treated with an ACE inhibitor. Four weeks after MI, cardiac function was assessed by Doppler echocardiography and non-infarcted myocardial mRNA expression by northern blot analysis. RESULTS: Cardiac function decreased significantly in the MI groups compared with the sham operated groups. Additionally, in the MI groups end diastolic dimension, E wave velocity, the ratio of peak velocity of E wave to A wave, deceleration rate of E wave, and mRNA expression of atrial natriuretic peptide, brain natriuretic peptide, and collagens I and III increased significantly compared with the sham groups. LV remodelling after MI was prevented in KO-MI mice compared with WT-MI mice. ACE inhibitor administration significantly attenuated progressive LV remodelling in both WT and KO-MI groups. CONCLUSION: ACE inhibitors can prevent the LV remodelling process that accompanies cardiac dysfunction after MI, even in AT1 KO mice. These findings suggest that ACE inhibitors prevent LV remodelling after MI by mechanisms other than inhibition of angiotensin AT1 receptor mediated effects.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2005

Tensile strength of mineralized/demineralized human normal and carious dentin.

The bond strengths of resins to caries-affected dentin are low. This could be due to weakened organic matrix. The purpose of this work was to determine if the ultimate tensile strength (UTS) of excavated carious dentin is weaker than that of normal dentin. Soft caries was excavated from extracted human molars, and the tooth was vertically sectioned into slabs. Each slab was trimmed to an hourglass shape, parallel or perpendicular to the tubule direction. Half of the specimens were mineralized, while the other half were completely demineralized in EDTA. ANOVA on ranks showed that the three-factor interactions (mineralization, caries, tubule direction) were all significant (p < 0.0001), indicating that mineralization and tubule direction gave different UTS results in normal and caries-affected dentin. No significant differences were seen between the UTS of normal and and that of caries-affected demineralized dentin in the parallel or perpendicular group. The matrix of demineralized caries-affected dentin was as strong as that of normal demineralized dentin when tested in the same direction.

Chelating Agents↗
PubMed2004

Effect of 2-hydroxyethyl methacrylate pre-treatment on micro-tensile bond strength of resin composite to demineralized dentin.

The purpose of this study was to evaluate the effect of 2-hydroxyethyl methacrylate (HEMA) application on the micro-tensile bond strength of resin composite to demineralized dentin. Artificially demineralized lesions were formed on bovine dentin surfaces and treated with 10, 30, 50, 70 and 100 wt% HEMA aqueous solution. The surfaces were then applied and covered with SE Bond and AP-X according to the manufacturer's instruction. After immersion in 37 degrees C water for 24 h, bond strength were measured using a universal testing machine. Bond strengths to both demineralized dentin and normal dentin, without HEMA application, were also measured. Scanning electron microscopic (SEM) observation and confocal laser scanning microscopy (CLSM) analysis at the resin-dentin interface were also performed. The bond strength data were statistically compared with anova and Scheffe's test (P < 0.05). Bond strength to demineralized dentin treated with over 30 wt% HEMA aqueous solution were significantly higher than that to demineralized dentin without HEMA application, but significantly lower than that to normal dentin. SEM observation revealed that the hybrid layer and resin-tags thickened and lengthened with HEMA application. In CLSM, the diffusion of adhesive primer into demineralized dentin increased with HEMA application. These results indicated that HEMA application might increase the bond strength to demineralized dentin by the enhancement of resin monomer penetration of HEMA.

Animals↗
PubMed2004

Micro-tensile bond strength of self-etching primer adhesive systems to human coronal carious dentin.

The aim of this study was to evaluate the micro-tensile bond strengths of three self-etching primer adhesive systems to normal dentin (ND), caries-affected dentin (CAD) and caries-infected dentin (CID). Human extracted molars with caries were used, and flat dentin surfaces ground by 600-grit SiC paper were prepared. The surfaces were dyed using Caries-Detector solution, treated with Clearfil SE Bond, Mac-Bond II and UniFil Bond, and then covered with resin composites according to manufacturer's instructions. After immersion in 37 degrees C water for 24 h, the teeth were serially sectioned into multiple slices. Each slice was distinguished into ND, CAD and CID groups by the degree of staining, and the bond strength was measured in a universal testing machine. Scanning electron microscopic (SEM) observation was also performed. For statistical analysis, anova and Scheffe's test were used (P < 0.05). The bond strengths of the three adhesive systems to CAD and CID were significantly lower than those to ND. There was significant difference in the bond strength to ND between Clearfil SE Bond and UniFil Bond, but no significant differences to CAD and CID among the three adhesive systems. On SEM, the hybrid layers in CAD and CID showed more porous structures compared with ND. The results indicated that the bond strengths to CAD and CID were not affected by a variety of self-etching primer adhesive systems because of the porous hybrid layer formation in carious dentin.

Dental Bonding↗
PubMed2004

Implications of plasma concentrations of adiponectin in patients with coronary artery disease.

OBJECTIVE: To investigate whether concentrations of plasma adiponectin constitute a significant coronary risk factor, with particular focus on the relation between plasma concentrations of adiponectin and the development of acute coronary syndrome (ACS). SUBJECTS AND METHODS: Plasma concentrations of adiponectin were measured in 123 patients with coronary artery disease (CAD) and in 17 control participants. Patients were divided into three groups according to condition type: acute myocardial infarction (AMI) group (n = 59), unstable angina pectoris (UAP) group (n = 28), and stable angina pectoris (SAP) group (n = 36). RESULTS: Plasma concentrations of adiponectin correlated negatively with body mass index (r = -0.18, p < 0.05), serum triglyceride (r = -0.25, p < 0.01), and fasting glucose concentrations (r = -0.21, p < 0.05), but correlated positively with age (r = 0.26, p < 0.01), high density lipoprotein cholesterol concentrations (r = 0.35, p < 0.01), and low density lipoprotein particle size (r = 0.37, p < 0.01). Plasma concentrations of adiponectin in patients with ACS, in both the AMI and UAP groups, were significantly lower than those in patients with SAP and in the control group (ACS, 6.5 (3.0) microg/ml; SAP, 11.3 (5.9) micro g/ml; control 12.8 (4.3) microg/ml; p < 0.01). Additionally, plasma concentrations of adiponectin in patients with CAD (7.9 (4.6) microg/ml, p < 0.01) were significantly lower than in the control group. There were, however, no significant differences between patients with SAP and the control group (p = 0.36). Multiple logistic regression analysis showed that smoking, fasting glucose concentration, and low log adiponectin concentration correlated independently with the development of an ACS. CONCLUSIONS: The findings suggest that measurement of plasma concentrations of adiponectin may be of use for assessing the risk of CAD and may be related to the development of ACS.

Adiponectin↗
PubMed2004

Acute haemodynamic benefits of biatrial atrioventricular sequential pacing: comparison with single atrial atrioventricular sequential pacing.

OBJECTIVE: To evaluate the acute effects on haemodynamic variables of biatrial pacing in comparison with high right atrial (HRA) pacing and left lateral atrial pacing. PATIENTS AND DESIGN: 23 patients were paced from the HRA site, the lateral site of the coronary sinus (CS), and both sites on two fixed atrioventricular delays (100 and 150 ms) during atrioventricular sequential pacing at 80 and 100 beats/min in random order. MAIN OUTCOME MEASURES: After five minute pacing, the maximum P wave duration on a 12 lead ECG, cardiac output, pulmonary capillary wedge pressure, and the transmitral flow pattern by transthoracic echocardiography were measured. RESULTS: Biatrial pacing delivered the shortest P wave duration (133 (25) ms, 133 (27) ms, and 96 (15) ms during HRA, CS, and biatrial pacing, respectively; p < 0.001), and the most improvement in cardiac output and pulmonary capillary wedge pressure (3.71 (0.93) l/min and 15 (7) mm Hg, 3.79 (0.97) l/min, and 14 (6) mm Hg, and 4.09 (1.01) l/min and 13(6) mm Hg during HRA, CS, and biatrial pacing, respectively; p < 0.01). Biatrial pacing most significantly decreased the intervals between the atrial pacing spike and the peak and end of the atrial filling wave (186 (16) ms and 250 (22) ms, 172 (19) ms and 242 (24) ms, and 153 (15) ms and 227 (23) ms during HRA, CS, and biatrial pacing, respectively; p < 0.001). It also significantly increased the mitral flow time velocity integral and peak atrial filling wave velocity (7.5 (3.4) cm and 63.8 (17.6) cm/s, 7.8 (3.0) cm and 62.4 (16.6) cm/s, and 8.3 (3.4) cm and 67.8 (19.3) cm/s during HRA, CS, and biatrial pacing, respectively; p < 0.05). The improvements in haemodynamic variables were especially remarkable in patients who had a longer interatrial conduction delay. CONCLUSIONS: Biatrial pacing yielded the most significant improvements in haemodynamic variables. These haemodynamic benefits may play a part in reducing intra-atrial pressure and preventing atrial fibrillation.

Atrial Fibrillation↗
PubMed2004

Early detection of cardiac involvement in patients with sarcoidosis by a non-invasive method with ultrasonic tissue characterisation.

OBJECTIVES: To clarify the value of cycle dependent variation of myocardial integrated backscatter (CV-IB) analysis, which non-invasively measures acoustic properties of the myocardium, for early detection of cardiac involvement in patients with sarcoidosis. METHODS: The study population consisted of 22 consecutive patients with biopsy proven sarcoidosis who did not have any abnormal findings on conventional two dimensional echocardiogram. Cardiac sarcoidosis was diagnosed by radionuclide testing including thallium-201 scintigraphy, gallium-67 scintigraphy, and cardiac fluorine-18-deoxyglucose positron emission tomography. The magnitude and delay of the CV-IB were analysed in the basal mid septum and the basal mid posterior wall of the left ventricle of all patients. RESULTS: The patients were divided into two groups: 8 patients with cardiac involvement and 14 patients without cardiac involvement. In the basal septum, a major reduction in the magnitude (mean (SD) 1.8 (4.4) v 6.6 (1.3), p = 0.012) and an increase in the time delay (1.3 (0.5) v 1.0 (0.1), p = 0.038) of CV-IB were observed in patients with cardiac sarcoidosis even in the absence of two dimensional echocardiographic abnormalities. The sensitivity for detecting cardiac involvement was such that the magnitude of CV-IB in the basal septum discriminated 75% of patients with cardiac sarcoidosis from those with non-cardiac sarcoidosis, whereas two dimensional echocardiographic parameters did not discriminate between these two groups. CONCLUSIONS: The CV-IB is decreased in the basal septum in patients with cardiac sarcoidosis even in the absence of two dimensional echocardiographic abnormalities. Analysis of CV-IB may be a useful method to detect early myocardial involvement in patients with sarcoidosis.

Cardiomyopathies↗