Biomedical subjects

Kazuo Takeda

Publications and source records attributed to Kazuo Takeda.

24 records · Page 2Linked to original sources

PubMed2002

Effects of atorvastatin on oxidized low-density lipoprotein, low-density lipoprotein subfraction distribution, and remnant lipoprotein in patients with mixed hyperlipoproteinemia.

Atorvastatin (10 to 20 mg/day) was administered for 3 months to 15 outpatients (average age 58 +/- 4 years) with hypercholesterolemia accompanied by hypertriglyceridemia without hypolipemic treatment. Changes in lipid profile, particularly oxidized low-density lipoprotein (LDL) (malondialdehyde LDL), subfractions of LDL, and remnant lipoprotein (RLP) cholesterol, were examined before and after administration. In addition, the influence of atorvastatin on lipoprotein(a) (known to be an independent risk factor for atherosclerosis), asymmetric dimethylarginine (known to be an endogenous inhibitor of nitric oxide synthase), and homocysteine (methionine metabolite) was also investigated. Administration of atorvastatin significantly decreased serum total cholesterol, LDL cholesterol, and triglycerides. Conversely, a significant increase in high-density lipoprotein cholesterol was shown. In LDL subfractions, large, buoyant LDL fractions were not influenced by treatment with atorvastatin (before administration, 99 +/- 14 mg/dl; after administration, 91 +/- 6 mg/dl, shown as a cholesterol content in each subfraction), but a marked decrease in small, dense LDL fractions (p <0.001) (before administration, 119 +/- 17 mg/dl; after administration, 43 +/- 10 mg/dl) was shown. Moreover, oxidized LDL was significantly decreased (p < 0.01) (before administration, 169 +/- 13 U/L; after administration, 119 +/- 10 U/L) and RLP cholesterol also was significantly decreased (p <0.01) (before administration, 11.9 +/- 2.0 mg/dl; after administration, 6.0 +/- 0.9 mg/dl) with atorvastatin treatment. No significant change was observed in fasting plasma glucose, hemoglobin A1c, lipoprotein(a), asymmetric dimethylarginine, homocysteine, and so on. These data suggest that administration of relatively low doses of atorvastatin to patients with hypercholesterolemia accompanied with hypertriglyceridemia results in a decrease not only in LDL cholesterol and triglycerides, but also in oxidized LDL and RLP cholesterol, with an increase in high-density lipoprotein cholesterol. Furthermore, small, dense LDL decreased with a shift in LDL subfractions to large, buoyant fractions, and these changes are considered to be involved in the inhibition of the onset and progression of atherosclerosis.

Anticholesteremic Agents↗

PubMed2002

Comparative effects of candesartan and enalapril on augmented vasoconstrictive responses to endothelin-1 in coronary vessels of spontaneously hypertensive rats.

BACKGROUND: The aim of this study was to compare the effect of angiotensin type-1 receptor blockade (ARB) on augmented vasoconstrictive response to endothelin-1 (ET-1) in coronary vessels of hypertensive hearts with angiotensin converting enzyme (ACE) inhibitor, candesartan cilexetil (CAN) or enalapril was administered for 3 weeks in spontaneously hypertensive rats (SHR). METHODS: We used SHR (9 to 12 weeks old, n = 18) and Wistar-Kyoto (WKY) rats (n = 6). Systolic blood pressure was measured once a week. Spontaneously hypertensive rats were divided into three groups. Enalapril malate (10 mg/day) or CAN (10 mg/day) was administered orally in each of six SHR in each group receiving treatment for 3 weeks. The control group (n = 6) received no treatment. At the end of this experiment, the hearts were isolated. Isolated hearts mounted on a Langendorff apparatus after weighing were then perfused with modified Krebs-Henseleit buffer at constant pressure (75 mm Hg). The coronary perfusion pressure and coronary flow were measured during perfusion of isolated hearts. Coronary vascular resistance (CVR; mm Hg/mL/min/100 g) was calculated. RESULTS: The ET-1 elicited increases in CVR dose-dependently in both normotensive and hypertensive rat hearts. However, the responses were significantly greater in SHR than in WKY rat. Chronic treatment with enalapril or candesartan inhibited the development of hypertension and cardiac hypertrophy equally in SHR. Augmented vasoconstrictive responses to ET-1 were significantly reduced in treated SHR. There was no difference in these effects between enalapril and candesartan. CONCLUSION: These findings suggest that both ACE inhibitors and ARB can equally inhibit augmented coronary vascular response to ET-1 in hypertensive hearts.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed2002

Effects of pravastatin on exercise electrocardiography test performance and cardiovascular mortality and morbidity in patients with hypercholesterolemia: Lipid Intervention Study in Kyoto.

The long-term effects of the 3-hydoxy-3-methyl-glutaryl coenzyme A reductase inhibitor, pravastatin, on exercise electrocardiography (ECG) test performance and cardiovascular mortality and morbidity were compared with those of conventional lipid-lowering drugs in hypercholesterolemic patients with no history of myocardial infarction or stroke. One thousand two hundred and seventeen patients were randomly assigned with mean serum cholesterol, triglyceride, high-density lipoprotein (HDL) cholesterol, and low-density lipoprotein (LDL) cholesterol levels of 6.98 +/- 0.91mmol/L, 2.08 +/- 1.87mmol/L, 1.38 +/- 0.44mmol/L, and 5.07 +/- 1.14 mmol/L, respectively, and received either pravastatin at a dose of 10-20mg/day (group P) or one of the conventional lipid-lowering drugs such as fibrates, nicotinic acid, and probucol (group C). The numbers of patients available for analysis in groups P and C were 305 and 278 at year 1, 261 and 216 at year 2, 206 and 184 at year 3, 159 and 122 at year 4, and 103 and 81 at year 5. Over the 3.2 year mean follow-up period, the reduction in serum LDL cholesterol levels was significantly greater (p<0.01) in group P (-24.3%) than in group C (-16.0%). Serum HDL cholesterol levels increased in group P (+11.6%), but decreased in group C (-0.3%) (p<0.01). There were no significant differences in the rate of patients who exhibited ischemic changes to exercise ECG test (ischemic responders) between the 2 groups. Coronary heart diseases (CHD) occurred in 6 patients in group P and 13 in group C; pravastatin significantly reduced CHD risk (reduction rate 0.369; 95% confidence interval 0.140-0.970; p<0.05). No significant differences existed between the treatment groups in terms of the number of strokes (group P, 6; group C, 7) or deaths unrelated to CHD (group P, 3; group C, 2). Although pravastatin did not improve the proportion of ischemic responders on exercise testing, it reduced CHD risk and serum LDL cholesterol levels more significantly than conventional lipid-lowering drugs without adversely affecting the risk of stroke and non-CHD death in hypercholesterolemic patients.

Adult↗

PubMed2002

Lowering of blood pressure improves endothelial dysfunction by increase of nitric oxide production in hypertensive rats.

To investigate the effects of angiotensin converting enzyme inhibitor (ACE-I) and other antihypertensive agents on the nitric oxide (NO) release during hypertension, seven- and fourteen-week-old SHR and deoxycorticosterone acetate (DOCA)-salt rats were treated with hydralazine, manidipine (Ca antagonist) or quinapril (ACE-I) for 3 weeks to lower blood pressure. Systolic blood pressure (SBP) was measured by the tail cuff method once each week. Endothelial cells (ECs) derived from the descending aorta of the treated rats were cultured and NOx levels in culture media were measured with an NO analyzer based on the Griess reaction. In both SHR and DOCA-salt rats, antihypertensive therapy lowered SBP to levels similar to those of control rats. The only exception was quinapril treatment of DOCA-salt rats. Although NOx release by ECs derived from hypertensive rats was improved by antihypertensive therapy, the effect was most pronounced in SHR treated with quinapril. In addition, restoration of NOx release was much more remarkable in younger SHR. NOx release was significantly higher in DOCA-salt rats treated with quinapril than in control rats without reduction of SBP. These results suggest that lowering blood pressure improves release of NO by ECs during hypertension and that the time at which antihypertensive therapy is started is also important to preserve endothelial function. Furthermore, ACE-I is suggested to protect endothelial function by increasing NO production in addition to lowering blood pressure.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed2002

Contrasting effects of angiotensin type 1 and 2 receptors on nitric oxide release under pressure.

This study was designed to test the hypothesis that increased pressure itself could cause endothelial dysfunction and lead to decreased nitric oxide (NO) release, partly through effects on the tissue renin angiotensin system in hypertension. Cultured endothelial cells (ECs) isolated from the aortas of WKY rats were continuously exposed to a pressure of 150 mmHg in a CO2 incubator for 72 h using a pressure system, and the NOx (NO2 and NO3) and angiotensin II (Ang II) concentrations in the supernatant were measured. An Ang II type 1 receptor (AT1R) antagonist (losartan) and an Ang II type 2 receptor (AT2R) antagonist (PD123319) were added to the medium. The expression of AT1R and AT2R mRNAs was also examined. Pressure loading significantly decreased the NO release from ECs. Concomitant administration of losartan restored NO release to the level before the application of pressure (p<0.001). This effect of losartan was blocked by simultaneous administration of PD123319, bradykinin type 2 receptor antagonist, and NO synthase inhibitor (p<0.05). The Ang II concentration was increased by pressure and was further increased by losartan. The gene expression of AT1R was not changed by pressure, but AT2R mRNA was increased almost 2-fold. These results indicate that high pressure itself attenuates NO release from ECs, and that losartan improves NO release by activating the bradykinin system via AT2R stimulation. In addition, the increase of AT2R gene expression in ECs during exposure to pressure may compensate for the reduction of NO.

Angiotensin II↗

PubMed2002

[Study on the determination of pesticide residues in crops by ion-trap GC/MS/MS].

Ion-trap GC/MS/MS was evaluated for the multi-residue determination of pesticides in agricultural products. Matrices were extracted from samples (spinach, carrot, onion and brown rice) with acetone and submitted to gel permeation chromatography, followed by a clean-up step through a graphite carbon cartridge. Thirty-five pesticides were added to either matrix, and analyzed by GC/MS/MS. Detection limits of pesticides by GC/MS/MS was almost the same as those by GC/MS (SIM). Coefficients of variation of peak area in 5 measurements of each pesticide at 0.1 microgram/mL or 0.05 microgram/mL with or without matrices were mostly acceptable, though those of 20 pesticides out of 35 were higher than 10% at a concentration of 0.02 microgram/mL. It was indicated that matrix artifacts, which interfere with GC/MS-Scan analysis, could be eliminated in some cases by using GC/MS/MS.

Crops, Agricultural↗