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Biomedical subjects

K Kamide

Publications and source records attributed to K Kamide.

28 records · Page 2Linked to original sources
PubMed1997

Influence of aging on progression of cardiovascular complications associated with insulin resistance in patients with essential hypertension.

Hyperinsulinemia or insulin resistance is suggested to play a role in the pathogenesis of hypertension and its target organ diseases. It is also well documented that aging is associated with a decline in glucose tolerance and insulin sensitivity, but there are few reports on the relationship between aging and insulin sensitivity or on the effects of aging on the progression of cardiovascular complications in patients with essential hypertension. To clarify these effects of aging in essential hypertension, 44 patients were examined by the euglycemic hyperinsulinemic glucose clamp test and ultrasonography of the heart and carotid arteries. There was a significant negative correlation between aging and insulin sensitivity (r = -0.37, p < 0.05). Significant increases in left ventricular mass index and carotid wall thickening accompanied by insulin resistance were seen in only non-elderly patients but not in elderly patients. These results suggest that aging decreases insulin sensitivity even in essential hypertensive subjects and that insulin resistance does not affect the progression of cardiac hypertrophy and atherosclerosis in elderly patients with essential hypertension.

Aged↗
PubMed1997

Recognition of tissue- and subtype-specific modulation of angiotensin II receptors using antibodies against AT1 and AT2 receptors.

Polyclonal antibodies have been prepared against synthetic peptides of human angiotensin II type-1 (AT1) and type-2 (AT2) receptors. Synthetic peptides corresponded to amino acids 15-24 of AT1 receptor and amino acids 241-253 of AT2 receptor. Western blot analysis of membranes from cell homogenates of COS-7 cells transfected with expression plasmids for mouse AT1b receptor, human vascular smooth muscle cells, and rat peripheral tissue demonstrated a major band of MW 44,000 with AT1 receptor antibody. Cell homogenates of COS-7 cells transfected with expression plasmids for human AT2 receptor showed a band of MW 44,000 with AT2 receptor antibody. Tissue homogenate of rat adrenal medulla and human pheochromocytoma presented a major band of MW 52,000 and a minor band of MW 44,000 with AT2 receptor antibody. AT1 receptor expression was in the following order: rat aorta > > lung, kidney, spleen, adrenal cortex > adrenal medulla, heart. Expression of AT2 receptor was in the following order: rat adrenal medulla > cortex, kidney, heart. Three-day treatment with CS866, an AT1 receptor antagonist, and temocapril, an angiotensin-converting enzyme inhibitor, suppressed AT1 receptor expression in the rat adrenal cortex, but not in the heart or adrenal medulla. AT2 expression was not affected by treatment with these drugs. These results suggest that newly developed antibodies for AT1 and AT2 receptors are useful in elucidating the regulation of subtype-specific receptor expression, and that AT1 but not AT2 receptors in adrenal tissue are regulated by angiotensin II.

Adrenal Glands↗
PubMed1996

Predominance of nocturnal sympathetic nervous activity in salt-sensitive normotensive subjects.

To assess the relation between salt sensitivity and autonomic nervous function by power spectral analysis of heart rate variability in normotensive subjects, low and high salt diets were given to 13 normotensive men (aged 25 to 39 years) for 4 days each. Autonomic function was assessed by power spectral analysis of R-R intervals based on an autoregressive algorithm from 24-h Holter electrocardiogram. Subjects whose mean blood pressure was increased more than 3 mm Hg by high salt diet were defined as salt sensitive (SS, n = 5), and the remainder as salt resistant (SR, n = 8). Using the low frequency (LF, 0.1 Hz) and high frequency (HF, 0.25 Hz) components, the LF to total power ratio (%LF) was used as a marker of sympathetic activity, and the HF to total power ratio (%HF) as a marker of parasympathetic activity. Compared to the daytime, SR revealed a decrease in %LF and an increase in %HF during the night on both diets. In SS, these circadian changes were observed only during low-salt diet. During the night, SS showed a higher %LF and a lower %HF than SR. Plasma catecholamines tended to be decreased by the high sodium diet in SR but not in SS subjects. These results suggest that the persistent nocturnal predominance of sympathetic nervous activity in a salt-sensitive men may contribute to the subsequent increase of blood pressure in these subjects.

Adult↗
PubMed1996

Impaired endothelial function with essential hypertension assessed by ultrasonography.

The objective of this investigation was to evaluate the role of hypertension in endothelial function, changes in which are known to be an early event of atherosclerosis. We assessed endothelial function in 13 subjects with normal blood pressure and 13 subjects with essential hypertension who had never been treated for hypertension or hyperlipidemia and who had no history of smoking or coronary or cerebrovascular disease. B-mode ultrasonography was used to measure the diameter of the brachial artery. Endothelium-dependent dilatation was assessed as the change in diameter of the artery during reactive hyperemia. Endothelium-independent dilatation was evoked, as a control, by sublingual administration of isosorbide dinitrate. Despite similar ages and lipid and glucose levels in the study groups, endothelium-dependent dilatation was less in patients with hypertension (13.1% +/- 1.6%) than in subjects with normal blood pressure (18.5% +/- 1.9%) (p < 0.05), whereas isosorbide dinitrate-induced changes were similar. Systolic and diastolic blood pressure were significantly correlated with endothelium-dependent vasodilatation (r = -0.57 and r = -0.53, respectively) but not with the change by isosorbide dinitrate. These results suggest that endothelial dysfunction exists in patients with hypertension and precedes overt atherosclerotic disease.

Adult↗
PubMed1996

Insulin resistance and cardiovascular complications in patients with essential hypertension.

Hyperinsulinemia or insulin resistance is suggested to play a role in the pathogenesis of hypertension and its target organ diseases. We designed this study to evaluate the role of insulin resistance in cardiac function, cardiac hypertrophy, wall thickness of the common carotid artery, and endothelial function of the brachial artery in essential hypertensive patients without diabetes mellitus. Insulin resistance was evaluated by the constant glucose infusion rate (M value) during the euglycemic-hyperinsulinemic glucose clamp test. In correlation analysis for several indices of glucose metabolism, only M value correlated with left ventricular mass index (LVMI), ratio of peak velocity during atrial contraction to that during early left ventricular filling phase (E/A ratio) and intima-media complex (IMC). In stepwise regression analysis of various risk factors for cardiovascular diseases, only M value and age were dependent factors for LVMI, E/A ratio, and IMC. No indices of glucose metabolism or risk factors for cardiovascular diseases correlated with endothelium-dependent and -independent vasodilation. These results suggest that insulin resistance, but not glucose intolerance and hyperinsulinemia, partly accelerates cardiovascular complications such as left ventricular hypertrophy and wall thickening of the carotid artery in patients with essential hypertension.

Blood Flow Velocity↗
PubMed1996

Links between hypertension and myocardial infarction.

The mechanisms through which hypertension contributes to the occurrence of myocardial infarction should be discussed from two points of view: (1) common risk factors for the two diseases, such as genetic risk, insulin resistance, sympathetic hyperactivity, and vasoactive substances such as angiotensin K, and (2) linking factors that are induced by hypertension and contribute to the development of atherosclerosis and myocardial infarction, such as atherosclerosis and left ventricular hypertrophy. Mechanical stress on blood vessels because of high blood pressure is an especially important factor in endothelial dysfunction, the progression of atherosclerosis, and plaque rupture. This article concentrates on these factors from the perspective of their relationship with the renin-angiotensin system, because recent multicenter trials have demonstrated that angiotensin-converting enzyme inhibitors are effective for preventing recurrence of myocardial infarction.

Arteriosclerosis↗
PubMed1991

Ferredoxin and ferredoxin-NADP reductase from photosynthetic and nonphotosynthetic tissues of tomato.

Ferredoxin and ferredoxin-NADP+ oxidoreductase (FNR) were purified from leaves, roots, and red and green pericarp of tomato (Lycopersicon esculentum, cv VFNT and cv Momotaro). Four different ferredoxins were identified on the basis of N-terminal amino acid sequence and charge. Ferredoxins I and II were the most prevalent forms in leaves and green pericarp, and ferredoxin III was the most prevalent in roots. Red pericarp of the VFNT cv yielded variable amounts of ferredoxins II and III plus a unique form, ferredoxin IV. Red pericarp of the Momotaro cv contained ferredoxins I, II, and IV. This represents the first demonstration of ferredoxin in a chromoplast-containing tissue. There were no major differences among the tomato ferredoxins in absorption spectrum or cytochrome c reduction activity. Two forms of FNR were present in tomato as judged by anion exchange chromatography and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. FNR II had a lower apparent relative molecular weight, a slightly altered absorption spectrum, and a lower specific activity for cytochrome c reduction than FNR I. FNR II could be a partially degraded form of FNR I. The FNRs from the different tissues of tomato plants all showed diaphorase activity, with FNR II being more active than FNR I. The presence of ferredoxin and FNR in heterotrophic tissues of tomato is consistent with the existence of a nonphotosynthetic ferredoxin/FNR redox pathway to support the function of ferredoxin-dependent enzymes.

Amino Acid Sequence↗
PubMed1989

Characterization and N-terminal sequence of a 5 kDa polypeptide in the photosystem I core complex from spinach.

Photosystem I core complexes were isolated from spinach photosystem I particles after heat treatment in the presence of 50% (v/v) ethylene glycol (heat/EG treatment). The core complex from 58 degrees C/EG-treated particles was composed of polypeptides with apparent molecular masses of 63, 60 and 5 kDA; this complex contained the iron sulfur center Fx but lacked center FA and FB. The core complex obtained from the 70 degrees C/EG-treated preparation lacked FX and contained a lesser amount of the 5 kDa polypeptide. The N-terminal amino acid sequence of the 5 kDa polypeptide did not correspond to the sequence derived from any possible reading frame in the chloroplast DNA of liverwort or tobacco. Twelve of the first 29 N-terminal amino acids were hydrophobic, suggesting that this protein is intrinsic to the photosystem I reaction center.

Amino Acid Sequence↗