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Biomedical subjects

T Omae

Publications and source records attributed to T Omae.

At least 19 recordsLinked to original sources
PubMed1995

Increased plasma levels of adrenomedullin in patients with heart failure.

OBJECTIVES: To investigate the role of adrenomedullin in the pathophysiology of heart failure, we measured plasma levels of adrenomedullin in patients with heart failure. BACKGROUND: Adrenomedullin is a potent hypotensive peptide newly discovered in pheochromocytoma tissue by monitoring its elevating activity on platelet adenosine 3',5'-cyclic monophosphate (cAMP). A significant level of adrenomedullin has been identified in human plasma. These findings suggest the possibility of adrenomedullin as a new circulating hormone that participates in the regulation of the cardiovascular system. METHODS: Venous blood samples at rest were obtained from patients with heart failure in New York Heart Association functional classes I (n = 15), II (n = 25), III (n = 16) and i.v. (n = 10) and from normal subjects (n = 27). Plasma adrenomedullin levels were determined by our newly developed radioimmunoassay. Other humoral factor levels measured simultaneously included norepinephrine, atrial natriuretic peptide, brain natriuretic peptide, plasma renin activity, aldosterone and cAMP. Left ventricular ejection fraction was measured by echocardiography. In eight patients with severe heart failure, plasma adrenomedullin levels were measured before and after treatment. RESULTS: The mean (+/- SD) plasma level of adrenomedullin in control subjects was 2.52 +/- 0.75 pmol/liter. Plasma levels of adrenomedullin in patients with heart failure were unaffected in those in functional class I (2.85 +/- 0.62 pmol/liter) but tended to be increased in those in class II (3.54 +/- 0.82 pmol/liter) and were significantly increased in those in classes III and i.v. (4.78 +/- 1.218 and 8.74 +/- 3.43 pmol/liter, respectively). There was a significant correlation between plasma levels of adrenomedullin and norepinephrine (r = 0.618, p < 0.001), atrial natriuretic peptide (r = 0.696, p < 0.001) and brain natriuretic peptide (r = 0.692, p < 0.001). Left ventricular ejection fraction inversely correlated with plasma adrenomedullin levels (r = 0.485, p < 0.001). Plasma adrenomedullin levels significantly decreased after treatment (from 7.40 +/- 3.40 to 3.98 +/- 1.00 pmol/liter, p < 0.05). CONCLUSIONS: These results suggest that plasma level of adrenomedullin are elevated in heart failure and that an increased plasma volume and an activated sympathetic nervous system in this condition may be related to its synthesis or secretion. Given that adrenomedullin exerts potent cardiovascular effects, increased adrenomedullin may be involved in the defense mechanism against further peripheral vascular resistance elevation in heart failure.

Adrenomedullin↗
PubMed1995

Improvement of insulin sensitivity for glucose metabolism with the long-acting Ca-channel blocker amlodipine in essential hypertensive subjects.

To clarify whether the long-acting calcium-channel blocker amlodipine restores insulin insensitivity in essential hypertension, insulin sensitivity tests were performed at the physiological steady-state insulin level (45 to 55 microU/mL) before and after amlodipine (2.5 to 7.5 mg/d) administration for 2 to 4 months in borderline and mild essential hypertensive subjects. Instead of somatostatin, Sandostatin (Sandoz, Basel, Switzerland) was used for the determination of steady-state plasma glucose (SSPG) in the same way as previously described. SSPG, which was initially high (212.9 +/- 18.0 mg/dL, mean +/- SE), was significantly reduced to 169.8 +/- 14.7 after amlodipine treatment. Responses of ketone bodies during the test at 30 minutes, which reflect the insulin effect on lipolysis in adipose tissue and hepatic fatty acid oxidation, also improved after amlodipine treatment. Norepinephrine, noted to be mildly elevated after amlodipine treatment, decreased during the sensitivity test at 2 hours probably due to the sedative effect, without any change in the fractional extraction of Na. This indicates that the physiological level of insulin does not activate sympathetic nerve activity or stimulate Na reabsorption. The long-acting calcium-channel blocker amlodipine has significantly improved the initially decreased insulin sensitivity for glucose metabolism at least partially in borderline or mild essential hypertension.

Amlodipine↗
PubMed1995

Role of systolic blood pressure in determining prognosis of hemodialyzed patients.

The role of blood pressure in determining the prognosis of hemodialyzed patients was examined in 195 patients who were introduced to hemodialysis. The relationship between blood pressure and survival or death was analyzed. In 46 patients who died within 3 years after the introduction of hemodialysis (nonsurvivors), the age was higher (61 +/- 2 years v 50 +/- 1 years), the occurrence of diabetic nephropathy was higher, and the systolic pressure was higher in both the introduction (178 +/- 4 mm Hg v 167 +/- 2 mm Hg) and maintenance (165 +/- 4 mm Hg v 147 +/- 2 mm Hg) phases than in 132 patients who survived more than 3 years (survivors). On the other hand, there were no significant differences in diastolic pressure during either phase between the two groups of patients. When diabetic nephropathy was excluded, only systolic pressure during the maintenance phase was higher in the nonsurvivors than in the survivors. Therefore, based on systolic pressure during the maintenance phase, patients were divided into two groups, the HT group (> or = 160 mm Hg) and the NT group (< 160 mm Hg), and cumulative survival rates were compared. Whether all patients, only those patients with diabetic nephropathy, or only those patients without diabetic nephropathy were examined, the survival rate was higher in the NT group than in the HT group.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1995

Plasma renin activity in hemodialyzed patients during long-term follow-up.

Plasma renin activity (PRA) and mean arterial pressure (MAP) were determined in 11 patients after the initiation of maintenance hemodialysis for 8 to 10 years. PRA increased significantly from 2.3 +/- 0.5 to 6.5 +/- 1.3 ng/mL/h, whereas MAP was lowered during follow-up, and there was a strong correlation between these two (r = 0.88, P < 0.001). Immediately before initiating hemodialysis, PRA was negatively correlated with the increase in PRA (r = 0.62, P < 0.05) and positively correlated with the reduction in MAP (r = 0.65, P < 0.05). PRA was elevated and MAP was markedly reduced in patients whose PRA was relatively low immediately before initiating hemodialysis, whereas PRA tended to be reduced and MAP was unchanged in patients with higher levels of PRA. These data suggest that renin secretion continues even after disuse atrophy of the kidneys with almost complete deterioration of its excretory function.

Adolescent↗
PubMed1995

Changes in plasma endothelin-1 concentration during blood volume depletion and expansion: role of the cardiopulmonary baroreflex.

To study the relationship between blood volume and the plasma level of endothelin-1 (ET-1), we examined the effects of blood volume depletion and expansion on the plasma ET-1 level in the rat. Anesthetized Wistar rats were subjected to hemorrhage (7 ml/kg), blood transfusion (7 ml/kg), or sham treatment. The same blood volume depletion and expansion were performed in other groups of rats, after bilateral cervical vagotomy or administration of intravenous atropine, to examine the role of the cardiopulmonary baroreflex. Hemorrhage produced mild decreases in the central venous pressure and arterial blood pressure, and an increase in the heart rate. Blood transfusion caused the opposite responses. The plasma ET-1 level was significantly higher in the volume-depleted rats (4.7 +/- 0.4 pg/ml, mean +/- SE, p < 0.05 vs. control), and was lower in the volume-expanded rats (2.6 +/- 0.2 pg/ml, p < 0.05) than in the control group (3.5 +/- 0.3 pg/ml). In the vagotomized rats, the blood volume depletion decreased and the volume expansion increased the central venous pressure and the arterial pressure, but they did not change the heart rate or the plasma ET-1 level. Vagal efferent inhibition with atropine did not affect the volume-induced changes in the plasma ET-1 level. These results indicate that the plasma level of ET-1 increases with blood volume depletion, and decreases with volume expansion. The cardiopulmonary baroreflex may play an important role in the regulation of plasma ET-1 levels when the blood volume is altered.

Animals↗
PubMed1995

Patient-hospital relationship and quality of life in elderly patients with hypertension.

To investigate the influence of the patient-hospital relationship on the quality of life (QOL) and on medication compliance in elderly patients with hypertension, we developed a comprehensive scale for assessing the patient-hospital relationship. In the first phase, an original questionnaire consisting of 40 items was designed under five fields for global assessment of the concept. We administered this questionnaire to 715 patients with cardiovascular diseases. Variations in the scores were evaluated by factor analysis. Three factors that comprised the majority of variance were derived by principal components analysis and varimax transformation. These orthogonal factors were considered to reflect "convenience of outpatient clinic", "satisfaction with clinical staff", and "communication with physician". We adopted three items under each of the three domains. Using this instrument, we assessed the patient-hospital relationship in 402 elderly outpatients with hypertension at 8 clinical centers. QOL and medication compliance were simultaneously assessed. A linear regression analysis revealed a significant positive correlation between patient-hospital relationship and QOL scores (r = 0.403, p < 0.0001), which means that patient-hospital relationship explained up to 16% of the total variability in scores on the Overall Quality of Life scale. The medication compliance was also better in patients with higher scores on the Patient-Hospital Relationship scale. These results indicate that the patient-hospital relationship is one of the substantial factors determining QOL and medication compliance in elderly patients with hypertension.

Aged↗
PubMed1995

Glomerular hemodynamics during supraventricular tachycardia.

Supraventricular tachycardia (SVT) was induced in 7 patients by programmed cardiac stimulation via an esophageal lead. Blood pressure, renal function, and hormonal factors were measured before, during, and after SVT. The glomerular filtration rate increased during SVT, while renal blood flow did not change. The parameters of glomerular hemodynamics were calculated according to the method of Gomez. Glomerular pressure was 64 +/- 3 (mean +/- SE) mmHg before SVT, and rose significantly (p < 0.01) to 76 +/- 5 during SVT. This rise in glomerular pressure was associated with a decrease in afferent vascular resistance (from 3355 +/- 610 to 1770 +/- 517 dynes x sec/cm5, p < 0.05) and an increase in efferent vascular resistance (from 3726 +/- 758 to 4814 +/- 780 dynes x sec/cm5, p < 0.05). Since atrial natriuretic peptide (ANP) increased during SVT (from 40 +/- 15 to 208 +/- 72 pg/ml, p < 0.01), these changes in glomerular hemodynamics may be attributed to the physiologic action of ANP. Despite the changes in glomerular hemodynamics during SVT, natriuresis appeared after SVT and not during SVT. This suggests that natriuresis accompanying SVT could not be attributed to the changes in glomerular hemodynamics.

Adult↗
PubMed1995

[Perceived quality of life and social factors in elderly hypertensive patients].

We conducted a cross-sectional study of elderly outpatients with hypertension to examine the relationship between quality of life (QOL) scores and social background factors. The subjects consisted of 516 outpatients (267 females), age of 60 or over, at nine clinics of major hospitals which participated in the National Cardiovascular Center Research Project. The perceived QOL was evaluated by the QOL scale originally based on Japanese patients with cardiovascular diseases. The scale consisted of the following 5 subscales; difficulty due to disease, psychological stability, independence, satisfaction in daily living and vitality. The background factors included family structure, socioeconomic factors and work status, and physical activity of daily living (ADL). After adjusting for age, sex, administered drugs and complicating conditions such as ischemic heart disease and/or apoplexy, a significant odds ratio of a low score of difficulty due to disease, psychological stability, satisfaction in daily living and vitality was found in the impaired physical ADL group with low socioeconomic class, and a significant odds ratio of low score of independence were found in the impaired physical ADL group who had lost jobs due to illness and had no children.

Aged↗
PubMed1995

Quantitative estimation of ideal body weight in uremic patients.

There is no definite way to estimate the ideal body fluid level in uremic patients. We developed a simple method to quantitatively estimate the ideal body weight. Hemofiltration (HF) was performed 9 times in 5 uremic patients. Urea-nitrogen concentration was measured in plasma before and after HF and in total ultrafiltrate mixture. Creatinine concentration was measured in plasma after HF and before the next HF and in urine collected between those two HF therapies. Total body fluid volume, TBF, was obtained, based on urea kinetics principles, as 36.8 +/- 1.8 L after HF assuming that urea is distributed uniformly within total body fluid. Creatinine generation rate, Gcr, was calculated as the sum of urinary creatinine excretion rate, creatinine accumulation rate within body fluids and extra-renal creatinine excretion rate. It is known that solid mass, SM, is related to Gcr and that the TBF to lean body mass (= SM + TBF) ratio is constant under ideal fluid level conditions. Thus, TBF under ideal body fluid level conditions (37.8 +/- 3.0 L), SM (13.7 +/- 1.1 kg) and fat mass (3.7 +/- 2.3 kg) were derived, and finally we found body weight value under ideal fluid level conditions to be 55.1 +/- 4.2 kg. The ideal body weight estimated this way was found to be significantly correlated with the dry weight (54.0 +/- 3.5 kg) determined clinically by conventional means (r = 0.9; p < 0.01); no significant difference was found between these body weight values. Our results suggest that the ideal body weight can be estimated simply by applying both urea and creatinine kinetics principles in uremic patients.

Adult↗
PubMed1994

Noninvasive quantitative evaluation of early atherosclerosis and the effect of monatepil, a new antihypertensive agent. An interim report.

In two studies on the same group of patients we evaluated noninvasive methods of assessing atherosclerosis and determined the effect of the new calcium channel-blocking agent monatepil on the progression of early atherosclerosis in humans. Computed tomography (CT) of the lower abdominal aorta and ultrasonography of the carotid arteries were used as noninvasive methods to determine the extent of atherosclerosis. To evaluate the CT images, we developed a new medical image analysis program. This enabled aortic calcification volume (ACV) to be quantified using plain CT images, and aortic wall volume (AWV) and aortic wall and calcification volume (AWCV) to be quantified from contrast CT images. Interobserver coefficients of variation of ACV, AWV, and AWCV (n = 8) were 4.7, 2.4, and 5.0%, respectively. In the monatepil study, the effect of the drug on serum lipid profiles was evaluated. Preliminary results show that shortly after monatepil administration, total serum cholesterol levels decreased significantly from 253.8 +/- 35.6 to 244.8 +/- 38.6 mg/dL (P < .009) and triglyceride levels tended to decrease. A positive correlation between the change in total cholesterol and changes in mean platelet volume was found (P = .028). Fasting immunoreactive insulin levels decreased in the four patients in which they were determined. Although this is a preliminary study, results indicate that CT of the lower abdominal aorta in combination with our new analysis program may be a precise, reproducible means of assessing early atherosclerosis. We have also shown that monatepil significantly decreases total cholesterol levels. However, the long-term effects of monatepil on the progression of atherosclerosis remain to be determined.

Aged↗
PubMed1994

Chronic effects of central and systemic administration of losartan on blood pressure and baroreceptor reflex in spontaneously hypertensive rats.

To clarify the role of endogenous angiotensin II (AngII) in the hypertension of spontaneously hypertensive rats (SHR), we examined the chronic effects of central and systemic administration of losartan, an angiotensin AT1 receptor antagonist, on blood pressure and arterial baroreceptor reflex. The SHR and Wistar-Kyoto rats (WKY), aged 12 to 16 weeks, received subcutaneous infusions of losartan at a dose of 10 mg/kg/day, or intracerebroventricular infusions of losartan at doses of 1 or 10 mg/kg/day for 14 days. Control groups received either isotonic saline solution subcutaneously or intracerebroventricular artificial cerebrospinal fluid. On day 14, baroreflex control of heart rate was determined by intravenous phenylephrine, and pressor response to intravenous AngII (100 ng/kg) was investigated in conscious rats. Blood pressure was higher and the sensitivity of the baroreflex control of heart rate was lower in vehicle-treated SHR than in WKY. Chronic subcutaneous administration of losartan lowered the blood pressure throughout the infusion period in both SHR and WKY, but the hypotensive effects were significantly greater in SHR. Losartan also sensitized the impaired baroreflex in SHR. Chronic intracerebroventricular losartan at a dose of 1 mg/kg/day did not alter the blood pressure or the baroreflex control of the heart rate in either strain. The effects of 10 mg/kg/day of intracerebroventricular losartan on blood pressure and the baroreflex were similar to those of the same dose administered subcutaneously. The pressor response to intravenous AngII was similarly inhibited by intracerebroventricular and subcutaneous losartan doses of 10 mg/kg/day.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMed1994

Idiopathic left innominate vein stenosis manifested following the creation of arteriovenous fistula in uremia.

A 48-year-old woman on maintenance hemodialysis was admitted with her left upper limb swollen and her left jugular vein dilated following the creation of an arteriovenous fistula on her left arm. The intracorporeal pressure during hemodialysis was found to be high. Venographic investigation showed severe stenosis of her left innominate vein accompanied by rich blood flow of the collaterals. Ligation of her fistula promptly reduced swelling of her left upper limb and dilatation of the left jugular vein. The exact cause of the stenosis could not be determined from venographic or computerized tomography findings. Idiopathic left innominate vein stenosis was diagnosed which we believe is the first case to be reported in a hemodialyzed patient.

Arteriovenous Shunt, Surgical↗
PubMed1994

Biphasic effects of repeated alcohol intake on 24-hour blood pressure in hypertensive patients.

BACKGROUND: The association between alcohol and blood pressure (BP) may be related to the temporal sequencing of alcohol use and BP measurement. We investigated the effects of single and repeated intakes of alcohol on 24-hour BP. METHODS AND RESULTS: Fourteen male habitual drinkers with essential hypertension were placed sequentially on a 4-day control phase: a nonalcoholic drink with the same calories as alcohol was given at dinner (5 PM to 6 PM) and a 7-day drinking phase: alcohol (ethanol, 1 mL/kg) was given at dinner under standardized conditions. Ambulatory BP measurements were performed on day 3 of the control phase and on days 1 and 7 of the alcohol phase. The average 24-hour systolic and diastolic BPs on day 1 were significantly lower than those in the control phase and on day 7. Between 6 PM and midnight, both systolic and diastolic BPs on days 1 and 7 (121 +/- 2/73 +/- 1 and 126 +/- 4/75 +/- 2 mm Hg, respectively) were significantly lower than those in the control phase (139 +/- 4/83 +/- 2 mm Hg). Between midnight and 8 AM (6 to 14 hours after the last drink), both systolic and diastolic BPs on day 7 (138 +/- 4/83 +/- 2 mm Hg) were significantly higher than those in the control phase (131 +/- 4/79 +/- 2 mm Hg) and day 1 (129 +/- 3/77 +/- 1 mm Hg). Between 8 AM and 3 PM, BPs showed no difference among the three phases. CONCLUSIONS: A single intake of alcohol has a depressor effect on BP that lasts for several hours after drinking, while repeated intakes for 7 days have both depressor and pressor effects according to the differences in time intervals after the last drink. This study suggests that the chronic effects of alcohol on BP might be overestimated when based on casual BP measurements alone.

Blood Pressure↗
PubMed1994

Periventricular white matter lucency and cerebral blood flow autoregulation in hypertensive patients.

The goal of this study was to elucidate the association between the development of periventricular white matter lucency and autoregulation of cerebral blood flow in hypertensive patients through the arteriovenous oxygen saturation difference method. We studied 51 hypertensive patients who had previously suffered from minor strokes (lacunar infarction, 43; deep basal minor hemorrhage, 8). Patients were divided into three groups based on the findings of periventricular white matter lucency. We measured the absolute value of resting cerebral blood flow using the argon inhalation method, and stepwise reduction of blood pressure was obtained with patients on a tilting table. Intracerebral venous blood sampling was accomplished by direct cannulation into the jugular vein up to the jugular bulb. We calculated several cerebral circulatory parameters, such as cerebrovascular resistance and cerebral oxygen consumption, and also delineated individual autoregulation curves. Cerebrovascular resistance was significantly greater in patients with severe periventricular white matter lucency than in patients without it (P < .05). Impaired autoregulation was also significantly more prevalent in patients with more severe periventricular lesions (P < .05). Multiple regression analysis revealed that the impaired autoregulation was significant and an independent determinant of the severity of such periventricular lesions (R = .34, P < .05). In conclusion, our findings indicated that hypertensive patients with severe periventricular white matter lucency were more likely to have impaired autoregulation of cerebral blood flow and suggest that stricter blood pressure control is required in such patients to prevent deterioration of the cerebral microcirculation.

Aged↗
PubMed1994

Clinical studies on the sites of production and clearance of circulating adrenomedullin in human subjects.

Adrenomedullin is a novel hypotensive peptide, newly discovered in pheochromocytoma. Because immunoreactive adrenomedullin is present in human plasma, adrenomedullin may play a role in regulating blood pressure. A recent report showed that human adrenomedullin mRNA is expressed not only in pheochromocytoma but also in the normal adrenal medulla, kidney, lung, and ventricle. However, whether or not these organs actually release adrenomedullin into the circulation remains unknown. To investigate the sites of production and degradation of adrenomedullin in human subjects, we obtained blood samples from various sites and measured immunoreactive adrenomedullin concentrations. In study 1, blood samples were obtained from the infrarenal inferior vena cava, suprarenal inferior vena cava, superior vena cava, right atrium, right ventricle, pulmonary artery, pulmonary capillary, left ventricle, and aorta during cardiac catheterization in 15 patients with ischemic heart disease (67 +/- 10 years). In study 2, blood samples were taken from the infrarenal inferior vena cava, suprarenal inferior vena cava, right and left renal veins, and left adrenal vein in 5 hypertensive patients (42 +/- 14 years) suspected of having renovascular hypertension. In study 3, peripheral venous blood samples were obtained in 2 patients (males, 45 and 36 years old) with pheochromocytoma at rest and during hypertensive attacks. Plasma adrenomedullin concentrations were measured by a newly developed radioimmunoassay. In study 1, there were no significant differences in plasma adrenomedullin concentrations in various sites of the right-side circulation. There was no step-up of plasma adrenomedullin levels in the coronary sinus. However, the plasma concentration of adrenomedullin in aorta was slightly but significantly lower than in pulmonary artery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Gland Neoplasms↗
PubMed1994

Plasma levels of adrenomedullin, a newly identified hypotensive peptide, in patients with hypertension and renal failure.

Adrenomedullin is a potent hypotensive peptide newly discovered in pheochromocytoma tissue by monitoring its elevating activity on platelet cAMP. We measured plasma concentration of adrenomedullin in patients with essential hypertension and chronic renal failure. As compared with normal subjects, plasma adrenomedullin was increased by 26% (P < 0.05) in hypertensives without organ damage and by 45% (P < 0.005) in those with organ damage. The increase in plasma adrenomedullin was more prominent in renal failure than in hypertension. Renal failure patients with plasma creatinine of 1.5-3, 3-6, and > 6 mg/dl had higher plasma adrenomedullin levels than healthy subjects by 78% (P < 0.05), 131% (P < 0.001), and 214% (P < 0.001), respectively. Moreover, adrenomedullin showed intimate correlations with norepinephrine, atrial natriuretic peptide, and cAMP in plasma (r = 0.625, P < 0.001; r = 0.656, P < 0.001; and r = 0.462, P < 0.001; respectively). Thus, plasma adrenomedullin is supposed to increase in association with changes in sympathetic nervous activity and body fluid volume in hypertension and renal failure. Considering its potent vasodilator effect, adrenomedullin may be involved in the defense mechanism preserving the integrity of the cardiovascular system in these disorders.

Adrenomedullin↗
PubMed1994

Reopening phenomenon in cardioembolic stroke observed by duplex carotid ultrasonography. Case reports.

The authors attempted to detect the reopening of an occluded artery within the carotid axis of acute cardioembolic stroke patients noninvasively by using duplex carotid ultrasonography. The timing of reopening as related to hemorrhagic transformation was also studied. For assessing the reopening phenomenon, quantitative measurement of flow velocity in the bilateral common carotid arteries was repeated in 10 patients who also underwent repeated angiography or autopsy. The ratio of the end-diastolic flow velocity (nonaffected/affected) was related to angiographic or autopsy findings. In 17 patients including the 10 cases mentioned, the occurrence of hemorrhagic transformation was related to the timing of reopening. The hemorrhagic infarction in this study was defined to be a hyperdense area in the basal ganglia on computed tomography. A significant decrease in the ratio of the end-diastolic velocity was observed in 6 patients, in whom the repeated angiography demonstrated reopening of the artery. Of the remaining 4 patients not showing a significant change, only 1 patient was found to have reopening. Reopening was detected in 12 of 17 cases. The timing was 2.5 hours after onset in 1, between days 2 and 5 in 6 cases, and after day 6 in 5 cases. Hemorrhagic infarction was found in 5 of the cases with reopening on days 2-5.

Aged↗