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Yoshiyuki Tamura

Publications and source records attributed to Yoshiyuki Tamura.

At least 19 recordsLinked to original sources
PubMed2006

Biperiden-induced delirium model in rats: a behavioral and electroencephalographic study.

AIMS AND METHODS: In order to elucidate the neural mechanisms of delirium, we administered the anticholinergic drug, biperiden (40 mg/kg i.p.), to 10 adult male Wistar rats and examined the resulting polygraphic recordings, including electroencephalography (EEG), electrooculography (EOG), and electromyography (EMG), for 60 min following injection. EEG data were investigated quantitatively by power spectrum analyses using fast Fourier transformation. Ten male Wistar rats receiving saline (i.p.) were used as the control group. RESULTS: Treated rats demonstrated two types of alternating behavioral change: a hyperactive and hypoactive state. In the hyperactive state, rapid walking, excessive random sniffing, and retropulsion were observed, with EEG desynchronization (significantly increased alpha1 (8.0-10.0 Hz), alpha2 (10.0-13.0 Hz), and beta (13.0-30.0 Hz) power values), as well as EEG slowing (significantly increased delta (0.5-4.0 Hz) and theta1 (4.0-6.0 Hz) power values): significantly marked rapid eye movement, and increased EMG activity. In the hypoactive state, motor arrest and drowsiness were observed, with prominent EEG slowing (significantly increased delta and theta1 power values): significantly decreased rapid eye movement and moderately decreased EMG activity. On the other hand, the control group did not show any behavioral or polygraphic changes. CONCLUSIONS: The behavioral and polygraphic changes induced by biperiden administration in rats are similar to those of delirium in humans. Therefore, it is proposed that biperiden-treated rats are a good delirium model and the anticholinergic mechanism is one of the potent factors in the development of delirium in humans.

Acetylcholine↗
PubMed2004

Lipid-altering changes and pleiotropic effects of atorvastatin in patients with hypercholesterolemia.

In this prospective study, we found beneficial short-term effects from atorvastatin therapy, including effects on low-density lipoprotein subfractions and remnant-like lipoprotein particle cholesterol, antioxidant effects, and alterations in endothelial function that may be important in early benefit from statin therapy; some effects would support much earlier benefit than previously reported. We also found long-term effects of atorvastatin, including decreased plasminogen activator inhibitor type-1 and additional significant alterations in low-density lipoprotein subfractions and endothelial function, supporting benefits from continuous long-term atorvastatin therapy beyond early reversal of hypercholesterolemia.

Adult↗
PubMed2004

Atrial electrophysiologic abnormalities in patients with Wolff-Parkinson-White syndrome but without paroxysmal atrial fibrillation.

BACKGROUND: Paroxysmal atrial fibrillation (PAF) frequently occurs in patients with Wolff-Parkinson-White (WPW) syndrome. HYPOTHESIS: The purpose of this study was to analyze the atrial electrophysiologic abnormalities and vulnerability to develop atrial fibrillation (AF) in patients with WPW syndrome but with no previous history of PAF. METHODS: We investigated atrial electrophysiologic abnormalities and vulnerability to AF in patients with WPW syndrome but without PAF. An electrophysiologic study was performed in 28 patients with WPW syndrome, 23 with atrioventricular nodal reentrant tachycardia (AVNRT) and 25 with other arrhythmias (control), all of whom had no history of PAF. The following atrial excitability parameters were assessed: effective refractory period (ERP), spontaneous or paced (A1) and extrastimulated (A2) atrial electrogram widths, percent maximum atrial fragmentation (%MAF; A2/A1 x 100), wavelength index (WLI; ERP/A2), and inducibility of AF. RESULTS: The ERP tended to be shorter in patients with WPW syndrome and in those with AVNRT than in the control group. The %MAF increased (154 +/- 33 vs. 137 +/- 23%, p < 0.05) and WLI decreased (2.7 +/- 0.8 vs. 3.4 +/- 1.0, p < 0.05) significantly in patients with WPW syndrome compared with the control group; however, these parameters in patients with AVNRT showed intermediate values. Atrial fibrillation was more inducible in patients with WPW syndrome (4/28 [14.3%]) than in those with AVNRT (4.3% [1/23]) and the control group (0/25 [0%]). With respect to patients with WPW syndrome and with and without inducible AF, the %MAF increased (195 +/- 23 vs. 148 +/- 30%, p < 0.01) and the WLI decreased (2.2 +/- 0.3 vs. 2.9 +/- 0.9, p < 0.05) in subjects with inducible AF. CONCLUSIONS: Atrial electrophysiologic abnormalities, especially atrial conduction delays, are more prominent in patients with WPW syndrome, even if they had no previous history of PAF. These abnormalities may play an important role in determining the vulnerability to AF.

Adolescent↗
PubMed2004

Time course differences for statin-induced pleiotropic effects in hypercholesterolemic patients.

BACKGROUND: It is unclear whether there are temporal differences for the pleiotropic effects for different members of the statin class. The present study investigated differences in the short- and intermediate-term pleiotropic effects of statins in hypercholesterolemic patients. METHODS: Thirty-five hypercholesterolemic patients were randomly treated with either atorvastatin or cerivastatin for 3 months. We measured fasting lipid concentrations, thiobarbituric acid reactive substances (TBARS), fibrinolytic parameters, and flow-mediated dilation of the brachial artery (FMD) at baseline and after 2 weeks and 3 months of therapy. RESULTS: After 2 weeks of therapy, atorvastatin decreased the low density lipoprotein (LDL) cholesterol, small, dense LDL cholesterol (34+/-22 vs. 18+/-20%, P<0.01), remnant-like particles (RLP) cholesterol (8.8+/-6.0 vs. 5.1+/-2.6 mg/ml, P<0.01), and TBARS (3.3+/-1.0 vs. 3.1+/-0.9 nmol/ml, P<0.05), and cerivastatin decreased LDL cholesterol. After 3 months of therapy, atorvastatin decreased small dense LDL cholesterol (8+/-13%, P<0.0001) additionally, and cerivastatin decreased small, dense LDL cholesterol (51+/-11 vs. 12+/-22%, P<0.0001) and plasminogen activator inhibitor type 1 (68+/-32 vs. 51+/-21 ng/ml, P<0.05). FMD increased significantly in both groups after 2 weeks, although the relative change in FMD was greater with cerivastatin therapy after 2 weeks than atorvastatin therapy (60+/-78 vs. 23+/-26%, P<0.05). However, FMD was the same for both groups after 3 months (58+/-65 vs. 66+/-61%, NS), because atorvastatin additionally increased FMD. There was no correlation between these pleiotropic effects and the improvement in the lipid profile for either group. CONCLUSIONS: These findings suggest that the degree of pleiotropic effect as well as the time course for the effect are different among members of the statin class of drugs.

Adult↗
PubMed2004

Elevated concentration of soluble vascular endothelial cadherin is associated with coronary atherosclerosis.

BACKGROUND: Vascular endothelial (VE)-cadherin, a Ca(2+)-dependent cell adhesion molecule, is expressed in atherosclerotic lesions by endothelial cells and is associated with neovascularization, although the relationship between circulating VE-cadherin and coronary artery disease has not been studied. METHODS AND RESULTS: The plasma concentration of VE-cadherin was measured in peripheral blood (femoral artery) and the coronary sinus of 24 patients with acute myocardial infarction (AMI), 26 with stable angina pectoris (AP), 18 with old myocardial infarction (OMI), and 30 control subjects (Control) who had no coronary artery stenosis on angiography. For the patients with AMI, blood samples were obtained in the acute (day 1) and chronic (day 21) phases. The plasma concentration of VE-cadherin was measured by enzyme-linked immunosorbent assay. The correlation between the plasma VE-cadherin concentration and the Gensini score was also determined as an index of the severity of coronary atherosclerosis. The plasma concentrations of VE-cadherin (ng/ml) in both the peripheral and coronary sinus blood were higher in patients with AMI, AP, and OMI than in the control subjects, and were similar in the 3 groups with coronary artery disease (femoral artery: AMI 5.1+/-2.5, AP 4.7+/-2.4, OMI 4.5+/-3.3, Control 2.6+/-2.3; coronary sinus: AMI 5.6+/-2.6, AP 5.0+/-2.3, OMI 5.0+/-2.9, Control 2.4+/-2.1, respectively). Plasma VE-cadherin concentrations were higher in the coronary sinus than peripheral blood samples in patients with AMI (p<0.01), AP (p<0.01), and OMI (p<0.05). The plasma VE-cadherin concentration was the same in the acute and chronic phases in patients with AMI. In the 3 groups of patients with coronary disease, both the peripheral plasma VE-cadherin concentration and the coronary sinus concentration correlated with the Gensini score (r=0.32, p<0.01 and r=0.42, p<0.001, respectively). Multiple regression analysis revealed that the plasma VE-cadherin concentration predicted the Gensini score independently of sex, age, hypertension, diabetes mellitus, smoking, and the lipid profiles. CONCLUSION: Increased secretion of VE-cadherin from the epicardial arteries is associated with the degree of coronary atherosclerosis, indicating the presence of atherosclerosis rather than disease activity.

Aged↗
PubMed2003

Increased soluble platelet/endothelial cell adhesion molecule-1 in the early stages of acute coronary syndromes.

Specific molecules including inflammatory cell adhesion molecules mediate attachment of blood leukocyte and platelets to the endothelium and mononuclear cell migration into the arterial intima. However, the clinical significance of soluble cell adhesion molecules very early in the course of acute coronary syndrome is not known. We assayed platelet/endothelial cell adhesion molecule-1 (PECAM-1, CD31), intercellular adhesion molecule-1 (ICAM-1, CD54), and P-selectin (CD62P) in plasma obtained from 20 patients within 3 h after the onset of acute myocardial infarction (AMI); 16 patients with unstable angina pectoris; 20 patients with stable angina pectoris, and 28 controls. Blood samples were obtained on hospital admission and again 1 week after onset of AMI and unstable angina, and on admission in patients with stable angina and controls. Plasma PECAM-1 concentration (ng/ml) on admission was higher in patients with AMI (25.6+/-4.7) and unstable angina (24.7+/-4.4) than in stable angina (20.5+/-4.4) and control (18.8+/-3.8) groups. In both AMI and unstable angina, plasma PECAM-1 had decreased significantly by 1 week (AMI, 20.8+/-4.0; unstable angina, 21.0+/-4.1). Plasma ICAM-1 concentration (ng/ml) on admission was higher in patients with AMI (254+/-70), unstable angina (264+/-78), and stable angina (245+/-68) than in controls (201+/-56), but did not differ between the three coronary syndromes. Plasma P-selectin concentration did not differ between the four groups, including controls. Therefore, soluble PECAM-1 concentration may be a sensitive markers providing early diagnostic aid in acute coronary syndromes.

Aged↗
PubMed2003

Relation of age and sex to atrial electrophysiological properties in patients with no history of atrial fibrillation.

Although atrial fibrillation is a common arrhythmia, especially in elderly men, little is known about age related changes in atrial electrophysiological properties or gender differences. The aim of this study was to analyze the effects of aging on vulnerability to atrial fibrillation and assessed gender differences in those age related changes. An electrophysiological study was performed on 73 patients with no history of atrial fibrillation, structural heart disease, or conditions with potential effects on cardiac hemodynamic or electrophysiological function, including 25 women (mean age 49 +/- 18 years; range 12-84 years). The following atrial excitability parameters were assessed: spontaneous or paced (A1) and extrastimulated (A2) atrial electrogram widths, percent maximum atrial fragmentation (A2/A1 x 100), effective refractory period, wavelength index (effective refractory period/A2), and inducibility of atrial fibrillation. There were no significant differences in percent maximum atrial fragmentation (143 +/- 28 vs 142 +/- 35%), effective refractory period (241 +/- 39 vs 238 +/- 50 ms), wavelength index (2.9 +/- 0.8 vs 3.1 +/- 0.9), induction of atrial fibrillation (10 [21%] vs 7 [28%]), or age (50 +/- 17 vs 49 +/- 20 years) between men and women. Age was not statistically different between those patients with and without induction of atrial fibrillation in men (48 +/- 14 vs 50 +/- 18 years) and women (48 +/- 18 vs 49 +/- 21 years). Percent maximum atrial fragmentation and effective refractory period were directly correlated with age in men (r = 0.35, P = 0.01; r = 0.46, P < 0.001, respectively) and women (r = 0.42, P = 0.04; r = 0.45, P = 0.02, respectively), though wavelength index did not correlate with age in men (r = -0.04) or women (r = -0.04) with no history of atrial fibrillation. Considering these findings, the authors conclude that the mechanism triggering atrial fibrillation may be different between older and younger patients with atrial fibrillation, because younger patients who have no marked substrate for atrial fibrillation may need many trigger beats to induce atrial fibrillation.

Adolescent↗
PubMed2003

Effects of atorvastatin therapy on the low-density lipoprotein subfraction, remnant-like particles cholesterol, and oxidized low-density lipoprotein within 2 weeks in hypercholesterolemic patients.

The short- and intermediate-term pleiotropic effects of atorvastatin were investigated in 18 hypercholesterolemic patients, as well as the temporal differences in these pleiotropic effects. Atorvastatin was given for 3 months and fasting lipid concentrations, thiobarbituric acid reactive substances (TBARS), fibrinolytic parameters, and flow-mediated dilation of the brachial artery (FMD) were measured at baseline and after 2 weeks and 3 months of therapy. Atorvastatin reduced the total cholesterol (273+/-34 vs 188+/-31 mg/dl, p<0.0001), low-density lipoprotein-cholesterol (LDL-C: 174+/-28 vs 111+/-23 mg/dl, p<0.0001), small, dense LDL-C (34+/-22 vs 18+/-20%, p<0.01), remnant-like particles cholesterol (RLP-C: 8.8+/-6.0 vs 5.1+/-2.6 mg/ml, p<0.01), and TBARS (3.3+/-1.0 vs 3.1+/-0.9 nmol/ml, p<0.05) after 2 weeks. Atorvastatin decreased the concentration of small, dense LDL-C again after 3 months (8+/-13%, p<0.0001). The plasma concentrations of the fibrinolytic parameters did not change significantly after 3 months of atorvastatin therapy. FMD increased significantly after 2 weeks (5.6+/-2.1 vs 6.3+/-2.0%, p<0.01) and additionally increased after 3 months of therapy (8.3+/-1.9%, p<0.0001). There were no correlations between the pleiotropic effects and the improvement in the lipid profile. The results indicate some short-term pleiotropic effects of atorvastatin therapy within 2 weeks, which may be important with respect to the early benefits of statin therapy.

Aged↗
PubMed2003

Occurrence of coenzyme forms of vitamin B12 in a cultured purple laver (Porphyla yezoensis).

Porphyra yezoensis (Susabinori, an edible purple laver), which was cultured aseptically for 12 weeks and then lyophilized, contained 50+/-2 microg/g of vitamin B(12) per 100 g dry weight. Coenzyme forms of vitamin B(12) (about 60% of the total vitamin B(12)) were found in the cultured purple laver aseptically, which may have the ability to biosynthesize the coenzymes.

Cells, Cultured↗
PubMed2003

Age-related changes in the electrophysiologic properties of the atrium in patients with no history of atrial fibrillation.

Although atrial fibrillation is a common arrhythmia, especially in the elderly, little is known about age-related changes in the electrophysiologic properties of the atrium. The aim of this study was to analyze the effect of aging on atrial vulnerability to atrial fibrillation. An electrophysiologic study was performed in 45 patients with no history of atrial fibrillation, Wolff-Parkinson-White syndrome, structural heart disease, or conditions with potential effects on cardiac hemodynamic or electrophysiologic function (15 females; mean age, 52 +/- 18 years; range, 14 to 84 years). The following atrial excitability parameters were assessed: spontaneous or paced (A1) and extrastimulated (A2) atrial electrogram widths, percent maximum atrial fragmentation (A2/A1 x 100), effective refractory period, wavelength index (ERP/A2), and inducibility of atrial fibrillation. Atrial fibrillation was induced in 9 patients. Percent maximum atrial fragmentation was greater (176 +/- 36 vs 137 +/- 26%, P < 0.001) and wavelength index was shorter (2.4 +/- 0.4 vs 3.2 +/- 0.9, P < 0.01) in the patients with than without inducible atrial fibrillation. However, age was similar in patients with and without inducible atrial fibrillation (47 +/- 11 vs 53 +/- 19 years, P = 0.36). Percent maximum atrial fragmentation and effective refractory period directly correlated with age (r = 0.32, P < 0.05 and r = 0.45, P < 0.001, respectively). On the other hand, wavelength index (3.1 +/- 0.9) did not correlate with age (r = -0.05, P = 0.77). This study suggests that the mechanism triggering atrial fibrillation may be very well different between older and younger patients with atrial fibrillation, because younger patients have no marked substrate for atrial fibrillation.

Adolescent↗
PubMed2003

Plasma levels of brain natriuretic peptide in various forms of obstruction to the left ventricular outflow tract.

BACKGROUND AND AIM OF THE STUDY: The study aim was to evaluate the relationship between plasma concentrations of brain natriuretic peptide (BNP) and the type or degree of stenosis in the left ventricular outflow tract (LVOT). METHODS: The relationship between BNP plasma level and pressure gradient (PG) in the LVOT and LV wall thickness (LVWth) was analyzed in 25 patients with a PG > or = 30 mmHg in the LVOT from the mid-left ventricle to the aortic valve. Among patients, 14 had aortic valve stenosis (AS), five had subaortic type hypertrophic obstructive cardiomyopathy (HOCM), three had mid-ventricular type HOCM, and three had angled ventricular septum. Three patients with AS showed LV systolic dysfunction (ejection fraction (EF) < 50%). All patients were in sinus rhythm. LV peak-systolic pressure (LVPSP) was derived by adding maximum PG to cuff systolic arterial pressure. RESULTS: In AS patients without LV systolic dysfunction and HOCM patients, there was a significant positive correlation between BNP and LVPSP (r = 0.78, p = 0.001; r = 0.76, p = 0.007, respectively). In AS patients without LV systolic dysfunction, BNP was positively correlated with LVWth (r = 0.79, p = 0.001), but no correlation was found between BNP and LVWth in patients with HOCM. In AS patients including systolic LV dysfunction, BNP was negatively correlated with LVEF (r = -0.87, p < 0.0001), but no correlation was found between BNP and LVEF in patients with HOCM. CONCLUSION: These results suggest that BNP level is closely associated with severity of stenosis in patients with HOCM, but mainly with severity of stenosis and also degree of LV systolic dysfunction in patients with AS. The BNP-LVWth relationship appeared to differ between AS (a fixed stenosis with uniform myocardial hypertrophy) and HOCM (a dynamic stenosis with uneven myocardial hypertrophy).

Aged↗
PubMed2003

Peroxyl radical scavenging capability of fish sauces measured by the chemiluminescence method.

Oxygen-related free radicals have been suggested as a cause of aging and various diseases, for example, various cancers and rheumatoid arthritis. A radical scavenger as an antioxidant has been sought in foods. Fish sauces are traditional Asian fermented seasonings. Using the luminol chemiluminescence method, the peroxyl radical scavenging capability of fish sauces was examined. From the IC50 values, many fish sauces have been shown to have a strong scavenging capability as well as soy sauces. A scavenging mechanism is also proposed.

Dose-Response Relationship, Drug↗