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Biomedical subjects

K Shimamoto

Publications and source records attributed to K Shimamoto.

At least 127 records · Page 7Linked to original sources
PubMed1999

Rationale for time-qualified reference standards for 24-hour blood pressure values and their circadian rhythms in Japanese normotensive adults: a study by the Ambulatory Blood Pressure Monitoring Research Group.

The aim of this study was to demonstrate that blood pressure (BP) has to be standardized according to its circadian variability, including the properties shown in its circadian rhythm. The BP time-qualified standards were derived from a sample of 644 clinically healthy normotensive Japanese subjects (320 males, 324 females; age range, 18-93 years), stratified by age-group and gender, who underwent noninvasive ambulatory monitoring according to a fixed protocol. The monitored data series shows that BP exhibits a within-day variability at any age of life in both males and females. Additionally, the monitored data series shows that BP exhibits a significant circadian rhythm at any age of life in both males and females. The age- and sex-related reference limits for the BP within-day variability constitute the time-qualified standards against which both the casual and monitored BP measurements can be compared in order to detect whether or not they are compatible with normotension. The reference limits for the BP circadian rhythm represent the rhythmometric standards against which the BP oscillatory curve can be compared in order to detect whether or not they are compatible with a physiological circadian rhythm.

Adolescent↗
PubMed1999

The contribution of nitric oxide to diuretic and natriuretic effects of renal kinins in normotensive rats.

We have reported that diuresis and natriuresis due to increase in renal kinins induced by the neutral endopeptidase 24.11 (NEP) inhibitor were attenuated by nitric oxide (NO) synthase inhibitor. To further clarify the water-sodium excretory mechanism of renal kinins, we estimated NO2+NO3 (NOx) and cGMP in plasma and urine with and without a specific NEP inhibitor, thiorphan. P-aminohippuric acid (PAH) and inulin were injected into male Sprague-Dawley rats. Vehicle (n = 8) or thiorphan (30 mg/kg, n = 10) was injected after the control period. Mean blood pressure (MBP), plasma and urinary PAH, inulin, NOx and cGMP, urinary volume (UV) and urinary sodium excretion (UNaV) were measured before and after injection of the reagents. MBP, renal plasma flow and glomerular filtration rate were not affected by thiorphan. Plasma NOx and cGMP with thiorphan did not differ from the vehicle, while urinary NOx and cGMP increased. None of the variables were affected by vehicle. UV and UNaV were higher with thiorphan than with vehicle. Positive correlation was found between urinary deltaNOx and deltacGMP. Each urinary deltaNOx and deltacGMP was significantly correlated to both deltaUV and deltaUNaV. Urinary NOx and cGMP were increased while maintaining correlations to UV and UNaV, but plasma NOx and cGMP were not affected by thiorphan. This implies that the mechanism of water-sodium excretion induced by NEP inhibitor is mediated by renal NO. Therefore, renal NO may contribute to the diuretic and natriuretic effects of renal kinins.

Animals↗
PubMed1999

Role of hyperinsulinemia in atherosclerotic coronary arterial disease: studies of semi-quantitative coronary angiography.

OBJECTIVE: To evaluate the role of insulin resistance on coronary atherosclerosis, angiographic semiquantitative scores of coronary stenosis and calcification were evaluated. SUBJECTS AND METHODS: Ninety-five non-diabetic subjects with coronary arterial disease were selected from our angiographic data base. Hyperinsulinemia was defined as a serum insulin level of > or = 60.4 IU/l at 120 minutes after 75 g oral glucose challenge. RESULTS: Twenty-three (24%) of the patients exhibited hyperinsulinemia. There was no difference in age or gender between the two subgroups. The incidence of hypertension, smoking habits, hypercholesterolemia, and hyperuricemia were also the same among the insulin resistance subgroups. Subjects with hyperinsulinemia had higher coronary artery scores of stenosis (11.9+/-5.6 vs 8.3+/-5.0, p<0.0001) and calcification (7.5+/-6.3 vs 4.8+/-4.9, p<0.0001). Moreover, the stenosis score had a close linear correlation with the 120 minutes serum insulin level (r=0.266, p=0.009), but not with the fasting level. CONCLUSION: These results suggest that hyperinsulinemia is a risk for coronary arterial disease, and emphasize the severity of coronary atherosclerosis in normal glucose tolerant subjects.

Adult↗
PubMed1999

[Multicenter prospective survey of prognosis of hypertensive elderly outpatient under antihypertensive treatment--morbidity and mortality of cardiovascular diseases and cancer].

Although calcium-channel blockers and angiotensin-I-converting enzyme inhibitors are often used for treatment of hypertension in the elderly in Japan compared to those in the United States and in European countries, there have been few investigations on the prognosis of the elderly receiving these antihypertensive treatments. The Research Group for "Guidelines on the Treatment of Hypertension in the Elderly" collaborated with the Comprehensive Research Projects on Aging and Health group of the Ministry of Health and Welfare of Japan in performing a 3-year survey on the outcome of 700 hypertensive elderly outpatients (> or = 60 years) receiving treatment of antihypertensive drugs. Antihypertensive drugs including dihydropyridine-type calcium channel blockers, beta blockers, angiotensin-I-converting enzyme inhibitors, diltiazem, diuretics and old-type antihypertensives (hydralazine, budralazine, and centrally acting drugs such as clonidine, methyldopa and guanabenz) were administered to 71.3%, 30.4%, 26.2%, 14.0%, 8.6%, and 6.4% of the 642 elderly patients surveyed for three years, at the time of registration, respectively. Morbidity and mortality rates of total cerebro-cardiovascular diseases, stroke, and heart diseases, were 27.6 and 7.81/1,000 patient-years, 15.1 and 3.6/1,000 patient-years, 10.4 and 4.2/1,000 patient-years, respectively. These results were similar or even better than those of megatrials of antihypertensive treatments for elderly patients in Europe and United States. After adjustment for potential confounding factors, multiple logistic analysis revealed that a past history of ischemic heart disease, use of the old-type antihypertensive drugs, male gender, and diastolic high blood pressure were independent risk factors for the morbidity of cerebro-cardiovascular diseases taking the group of non-cerebro-cardiovascular disease as the reference group. We also identified 22 cases of newly occurred malignancies including 7 fatal cases. However, none of the antihypertensives was significantly related to the occurrence of malignancies. These results lead support to the tendencies in the use of antihypertensive drugs in Japan.

Aged↗
PubMed1999

[Prognosis predictor of chronic-stage acute myocardial infarction].

An investigation of acute myocardial infarction (AMI) was performed in Obihiro City, Hokkaido from October 1.1990 to March 31.1996. Based on the recorded cases, we conducted an investigation on the progress of 194 survivors by questionnaires, and we investigated the factors affecting long-term prognosis of AMI. The mean follow-up period was 1.62 years. The mean age at onset and frequency of hypertension were higher in women than in men. On the other hand, a larger percentage of men smoked and drank alcohol. Kaplan-Meier analysis showed that survival was strongly influenced by aging, drinking, prior history of AMI or stroke, renal dysfunction, cardiac failure and early rehabilitation. Using Cox's hazard model, it was found that mortality risk increases 1) by 1.5 times for an increase of 10 years in age (2.6-times higher for people over 65 years old), 2) by 2.5 times for people with a history of AMI or stroke, 3) by 4.6 times for people with renal dysfunction, and 4) by 5.7 times for people with cardiac failure of Killip class III or IV. On the other hand, it was found that mortality risk decreases 1) by 0.3 times for people who drink alcohol, 2) by 0.1 times for people who have undergone PTCA, and 3) by 0.3 times for people who have undergone rehabilitation. The mortality risk is high for people who do not drink alcohol and those who have not undergone rehabilitation using Cox's hazard model adjusted all those factors. In conclusion, prognostic predictor in chronic-stage acute myocardial infarction are aging, drinking, prior history of AMI or stroke, renal dysfunction, cardiac failure, early rehabilitation, and PTCA. The results also indicated that, regardless of the historical and clinical characteristics, early rehabilitation is very important to increase the probability of long-term survival.

Aged↗
PubMed1999

[The effects of angiotensin II receptor antagonists on glucose, lipid, and uric acid metabolism in essential hypertensives].

Many of hypertensive individuals have glucose intolerance, dyslipidemia and hyperuricemia. It is important to take care of these metabolic disease for not only the progression hypertension itself but also the prevention of atherosclerosis. We reviewed the effects of angiotensin II receptor antagonists on glucose, lipid, and uric acid metabolism in essential hypertensives.

Angiotensin Receptor Antagonists↗
PubMed1999

[The effects of angiotensin II receptor antagonists on insulin resistance].

Many of hypertensive individuals have glucose intolerance and dyslipidemia, and insulin resistance is common disorder on the basis of these diseases. It is important to take care of these metabolic disease for not only the control of hypertension, blood glucose and hyperlipidemia, but also the prevention of atherosclerosis. We reviewed the effects of angiotensin II receptor antagonists on insulin resistant syndrome.

Angiotensin Receptor Antagonists↗
PubMed1998

Down-regulation of RFL, the FLO/LFY homolog of rice, accompanied with panicle branch initiation.

FLORICAULA (FLO) of Antirrhinum and LEAFY (FLY) of Arabidopsis regulate the formation of floral meristems. To examine whether same mechanisms control floral development in distantly related species such as grasses, we isolated RFL, FLO-LFY homolog of rice, and examined its expression and function. Northern analysis showed that RFL is expressed predominantly in very young panicle but not in mature florets, mature leaves, or roots. In situ hybridization revealed that RFL RNA was expressed in epidermal cells in young leaves at vegetative growth stage. After the transition to reproductive stage, RFL RNA was detected in all layers of very young panicle including the apical meristem, but absent in the incipient primary branches. As development of branches proceeds, RFL RNA accumulation localized in the developing branches except for the apical meristems of the branches and secondary branch primordia. Expression pattern of RFL raised a possibility that, unlike FLO and LFY, RFL might be involved in panicle branching. Transgenic Arabidopsis plants constitutively expressing RFL from the cauliflower mosaic virus 35S promoter were produced to test whether 35S-RFL would cause similar phenotype as observed in 35S-LFY plants. In 35S-RFL plants, transformation of inflorescence meristem to floral meristem was rarely observed. Instead, development of cotyledons, rosette leaves, petals, and stamens was severely affected, demonstrating that RFL function is distinct from that of LFY. Our results suggest that mechanisms controlling floral development in rice might be diverged from that of Arabidopsis and Antirrhinum.

Amino Acid Sequence↗
PubMed1998

Effect of protein kinase C inhibitors on cardioprotection by ischemic preconditioning depends on the number of preconditioning episodes.

OBJECTIVES: This study examined the possibility that the role of PKC in [corrected] PC, and thus the response to PFC inhibitors, may differ depending on how many ischemic episodes are employed to precondition the heart. METHODS: In the first series of experiments, myocardial infarct was induced by 30 min of coronary occlusion and 3 h of reperfusion in the rabbit. Infarct size was determined by tetrazolium staining and expressed as a percentage of area at risk (%IS/AR). Prior to the 30-min ischemia, rabbits were subjected to no PC, single PC (i.e., PC with an episode of 5 min ischemia/5 min reperfusion), and repetitive PC (2 cycles of 5 min ischemia/5 min reperfusion) with or without one of three treatments: polymyxin B (PolyB), staurosporine (Stauro), and 8-sulfophenylthephylline (SPT). In the second series of experiments, the rabbits received 5 min of coronary occlusion after repetitive PC with or without PolyB or Stauro treatment. Then, myocardial tissue in the ischemic region was sampled for assay of PKC activity. Untreated rabbits served as controls. RESULTS: Single and repetitive PC limited %IS/AR to the same extent (%IS/AR = 9.8 +/- 1.9 and 10.4 +/- 2.3, both p < 0.05, vs. the control value of 44.5 +/- 3.4), and single PC was blocked by PolyB (%IS/AR = 43.9 +/- 2.7) and Stauro (%IS/AR = 31.5 +/- 3.2). Although the protocol of PolyB injection maintained the plasma PolyB level during sustained ischemia well above its Ki for PKC, this agent and also Stauro failed to abolish the protection by repetitive PC (%IS/AR = 21.6 +/- 3.0 and 11.4 +/- 4.3, respectively). SPT, an adenosine receptor antagonist, not only blocked single PC (%IS/AR = 44.4 +/- 4.4) but also attenuated protection by repetitive PC (%IS/AR = 28.3 +/- 3.6). Infarct sizes in non-preconditioned hearts were not modified by PolyB, Stauro, or SPT. The ratio of membrane fraction PKC activity to cytosolic fraction PKC activity was elevated by repetitive PC plus 5 min ischemia, and this change in PKC was inhibited in hearts given PolyB and Stauro. CONCLUSIONS: In contrast to single PC, repetitive PC protects the heart against infarction even when PolyB and Stauro are administered to inhibit PKC during ischemic insult. This difference may be attributable to a PKC-independent mechanism, in which the adenosine receptor may be partly involved.

Animals↗
PubMed1998

Preoperative staging of thyroid papillary carcinoma with ultrasonography.

OBJECTIVE: To evaluate the usefulness of ultrasonography including Doppler flow imaging for the preoperative staging of thyroid papillary carcinoma. MATERIALS AND METHODS: In 77 patients with thyroid papillary carcinoma who underwent total thyroidectomy, the accuracy of ultrasonography in preoperative clinical staging was assessed with use of pathologic examination on the basis of TNM classification by the International Union Against Cancer (UICC). RESULTS: In 63 (81.8%) cases, T categories were estimated accurately. The sensitivity in depicting tumor extension into the prethyroidal muscle and/or the sternocleidomastoid muscle was 77.8%, whereas the sensitivity for invasion into the trachea and the esophagus was 42.9 and 28.6%, respectively. In 37 (48.1%) cases, N categories were underestimated, and the sensitivity in the detection of regional lymph node metastasis was 36.7%. Doppler flow imaging was performed in 36 patients, and no correlation was found between flow patterns and the presence of local invasion or regional lymph node metastasis. CONCLUSION: Ultrasonography was useful for preoperative investigation of thyroid papillary carcinoma, but several limitations existed, especially in evaluating extracapsular invasion to deep locations and regional lymph node metastasis.

Adult↗
PubMed1998

Effects of the angiotensin converting enzyme inhibitor temocapril on insulin sensitivity and its effects on renal sodium handling and the pressor system in essential hypertensive patients.

The effects of the angiotensin converting enzyme (ACE) inhibitor temocapril on insulin sensitivity and its effects on renal sodium handling and the pressor system were investigated in essential hypertensive patients (EHT). Seven EHT were hospitalized and underwent a 2-h euglycemic hyperinsulinemic glucose clamp before and after 2 weeks' administration of temocapril (4 mg/day). Insulin sensitivity was calculated using the M value from the infusion rate of glucose with hyperinsulinemia using the glucose clamp method. Renal clearances of sodium, lithium, creatinine, and paraaminohippuric acid were used to calculate fractional proximal and distal tubular reabsorption of sodium (FPR(Na), FDR(Na)) and renal plasma flow (RPF) before and during insulin infusion by the glucose clamp method. Temocapril decreased blood pressure and increased M value significantly. Before temocapril treatment, hyperinsulinemia by the glucose clamp induced significant decreases of urinary excretion of sodium (U(Na) V) and fractional excretion of sodium (FENa). After treatment, these decreases were attenuated, and the change of U(Na) V (deltaU(Na) V) with hyperinsulinemia was significantly higher and deltaFENa showed a higher tendency, compared with before the treatment. FPR(Na) showed no change with hyperinsulinemia before treatment, but significantly decreased after treatment. DeltaFPR(Na) was significantly lower after treatment than that before treatment. FDR(Na) showed an increase with hyperinsulinemia, and deltaFDR(Na) was similar between before and after treatment. RPF showed no change with hyperinsulinemia, and no difference was found in deltaRPF between before and after treatment. Plasma norepinephrine level (PNE) and plasma renin activity (PRA) showed increases, whereas plasma aldosterone concentration (PAC) did not change with hyperinsulinemia. There were no significant differences in deltaPNE, deltaPRA, and deltaPAC between before and after treatment. From these results, it is suggested that in EHT 1) temocapril improves insulin resistance, and 2) although temocapril shows no significant influence on the augmentation of pressor systems by hyperinsulinemia, this agent attenuates the sodium-retaining action of hyperinsulinemia, which may be attributable to suppression of insulin-induced sodium reabsorption at the proximal tubules. These effects may lead to additional beneficial effects in the treatment of essential hypertensives with insulin resistance.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1998

Effects of aging on the insulin actions for the glucose metabolism and renal function in normotensives and essential hypertensives.

It has been suggested that hyperinsulinemia compensating insulin resistance in glucose metabolism may be a pathogenic factor in essential hypertension. On the other hand, age-associated increases in the prevalence of glucose intolerance and hypertension are also well established. The aim of this study is to clarify the influence of aging on insulin sensitivity in glucose metabolism and on renal sodium handling under hyperinsulinemia, which may relate to high blood pressure in insulin-resistant subjects. Fifty-two normotensive subjects and 61 patients with essential hypertension were evaluated in this study. The subjects of these groups were divided into young (<40 years old) and middle-elderly (> or = 40 years old): young normotensives (Y-NT, n = 22); middle-elderly normotensives (ME- NT, n = 30); young hypertensives (Y-HT, n = 9); and middle-elderly hypertensives (ME-HT, n = 52). Using the euglycemic hyperinsulinemic glucose clamp, insulin sensitivity was assessed as M value. Just before the start and the termination of the glucose clamp, creatinine clearance (Ccr) and urinary excretion of sodium (UNaV) were measured. In addition, renal plasma flow assessed as para-aminohippuric acid clearance was also measured at the same time in several subjects; 8 Y-NT, 8 ME-NT, 3 Y-HT, and 10 ME-HT. The M value was significantly lower in ME-NT, Y-HT, and ME-HT, compared to Y-NT, although blood sugar and immunoreactive insulin levels were similar in all four groups. In normotensive subjects, there was a significant, negative correlation between age and M value. However, this correlation was not observed in hypertensive patients. UNaV decreased in ME-NT, Y-HT, and ME-HT, but not in Y-NT under hyperinsulinemia by the glucose clamp, whereas Ccr showed no significant change in any group. In all subjects, the change of UNaV (deltaUNaV) correlated significantly and positively with the M value. Renal plasma flow significantly increased under hyperinsulinemia by the glucose clamp in only Y-HT, but not in the other groups. There was a significant, positive correlation between deltaUNaV and the change of renal plasma flow under hyperinsulinemia by the glucose clamp. These results suggested that both the impairments of the insulin sensitivity and insulin-induced vasodilation at the renal artery with aging may partially contribute to age-related elevation of blood pressure through renal sodium retention by compensating hyperinsulinemia. On the other hand, it seems reasonable to assume that these abnormalities, which can contribute to high blood pressure in essential hypertension, already may exist at lower ages in essential hypertensive patients.

Adolescent↗