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Biomedical subjects

Y Miyahara

Publications and source records attributed to Y Miyahara.

At least 19 recordsLinked to original sources
PubMed1998

An elevation of stem cell factor in patients with hyperthyroid Graves' disease.

Graves' disease is an autoimmune disorder characterized by the presence of antibodies against thyrotropin receptor (TRAb). Stem cell factor (SCF), derived from bone marrow, is known to promote lymphohematopoiesis. To investigate the relation between the alteration in plasma levels of SCF, thyroid hormone status, and TRAb measured by thyrotropin binding inhibition (TBI), 13 untreated, 21 treated, and 4 relapsed hyperthyroid Graves' disease patients, 21 patients with Hashimoto's thyroiditis, 6 patients with subacute thyroiditis, and 11 control subjects were examined. In untreated hyperthyroid Graves' disease patients, serum levels of thyroxine (T4) and triiodothyronine decreased rapidly by methimazole treatment, and TBI decreased progressively, but variably. Simultaneously, the elevated plasma levels of SCF decreased gradually and progressively. The plasma levels of SCF correlated curvilinearly with the serum levels of T4. In 4 patients with relapsed hyperthyroid Graves' disease, TBI was marginally positive in 3 patients and negative in 1, but plasma levels of SCF were elevated significantly in all 4 patients. In patients with subacute thyroiditis and Hashimoto's thyroiditis with or without T4 replacement, plasma levels of SCF did not differ from that of controls. These findings indicate that the elevation of plasma levels of SCF relates to the longstanding thyrotoxic state and that short-term thyrotoxicosis does not significantly affect plasma levels of SCF. It remains to be determined whether the elevation in plasma levels of SCF is induced by excess thyroid hormone, reflecting the hypermetabolic state, or whether the elevation of plasma levels of SCF contributes to stimulation of lymphocytes producing TRAb.

Acute Disease↗
PubMed1998

Two cases of adult varicella accompanied by hepatic dysfunction.

Varicella is a typical acute exanthematous viral infection caused by varicella-zoster virus (VZV). In recently years, as far as hepatic dysfunction caused by viruses other than the hepatitis virus is concerned, there have been a few reports on hepatic dysfunction accompanying varicella following organ transplantation of Europe and America and another report on an immunocompromized adult following treatment for Systemic lupus erythematosis (SLE) in Japan. Nonetheless, we searched the MEDLINE and J MEDICINE listing the publications between 1986 and 1996 and found one report on healthy adults with varicella accompanied by hepatic dysfunction in Europe and America and two reports in Japan. Only Noguchi et al. dealt with the findings of liver biopsy. We examined two healthy adults with varicella and mild-to-moderate hepatic dysfunction, and referred to the results of their liver biopsies. The present paper discusses this issue, citing some references.

Adult↗
PubMed1998

Astemizole-induced torsades de pointes in a patient with vasospastic angina.

Astemizole (Hismanal), an antihistamine agent, has been reported to be associated with ventricular arrhythmias. In this paper we present a case of QT prolongation and torsades de pointes (TdP) in a 77-year-old woman who had been taking astemizole (10 mg/day) for 6 months because of allergic skin disease. At the time of admission, the serum concentration of astemizole and its metabolites was markedly elevated at 15.85 ng/ml, approximately 3 times the normal level. The patient was also taking cimetidine, a known inhibitor of cytochrome P-450 enzymatic activity, and during her admission was diagnosed as having vasospastic angina. To the best of our knowledge, this is the first report of astemizole-induced QT prolongation and TdP in Japan.

Aged↗
PubMed1998

Liddle's syndrome in an elderly woman.

A 78-year-old woman with hypertension was hospitalized with acute bronchitis. However, she was also found to have hypernatremia, hypokalemia, and metabolic alkalosis. Detailed examination showed a low plasma renin activity and plasma aldosterone concentration. A provisional diagnosis of Liddle's syndrome was established and the patient was successfully treated with triamterene. Although Liddle's syndrome is generally considered an inherited hypertensive disease found in young people, a review of the literature indicated that muscle weakness is an important clinical finding in elderly patients with this disease. Liddle's syndrome should be considered in the differential diagnosis of hypertension even in elderly individuals.

Aged↗
PubMed1997

An abnormal sodium metabolism in Japanese patients with essential hypertension, judged by serum sodium distribution, renal function and the renin-aldosterone system.

OBJECTIVE: The role of the renin-aldosterone system and the ability of renal sodium reabsorption to facilitate pressure natriuresis were analyzed by using a sufficient number of Japanese patients with essential hypertension. METHODS: We studied 3222 normal Japanese subjects (610 in Kashiwa City Hospital and 2612 in Shinshu University Hospital), 741 Japanese patients with essential hypertension (256 in Kashiwa City Hospital and 485 in Shinshu University Hospital), 20 patients with aldosterone-producing adenomas and 11 patients with idiopathic hyperaldosteronism to determine the possible roles of sodium, renal function, and plasma aldosterone concentration (PAC) on blood pressure elevation. Inappropriate elevation of aldosterone levels [elevation of the aldosterone:plasma renin activity (PRA) ratio] was used to assess aldosterone action. RESULTS: The peak of the serum sodium distribution curve was approximately 2 mmol/l higher in the patients with essential hypertension than it was in controls. The prevalence of higher serum sodium concentrations (> or = 147 mmol/l) also was increased significantly hypertensive patients. Age-related deterioration of renal function did not explain the hypertension and abnormal sodium metabolism in the hypertensive patients. In stepwise regression analysis, the serum sodium concentration was related inversely to the PRA and positively to the PAC:PRA ratio. Although there was an inverse relationship between urinary sodium excretion (representing sodium intake) and the PRA, urinary sodium excretion proved not to be significant as a source of variation in the PAC or in the PAC:PRA ratio in the hypertensive patients. Although the PAC was within the normal range in patients with serum sodium concentrations of 147 mmol/l or more and an elevated PAC:PRA ratio, it was inappropriately high for the stimulus applied, as indicated by the PRA; this is similar to the situation with aldosterone-producing adenomas or idiopathic hyperaldosteronism. CONCLUSION: Serum sodium distribution patterns differed between normal subjects and patients with essential hypertension in this Japanese population. The deterioration of renal function and increased sodium intake did not explain this abnormal sodium metabolism. A higher serum sodium concentration is related to an elevated blood pressure, and, in some patients, an inappropriate elevation of plasma aldosterone levels. Of the Japanese hypertensive patients, 10-14% exhibited serum sodium concentrations of 147 mmol/l or more and inappropriate elevations of aldosterone level (suppressed PRA and normal aldosterone level). The defect in these patients presumably lies in the inappropriately high secretion of aldosterone.

Adult↗
PubMed1997

Porphyria cutanea tarda with constrictive pericarditis in a family.

Two cases of familial porphyria cutanea tarda (PCT) with constrictive pericarditis are described. A 50-year-old woman and her 48-year-old younger brother were admitted because of right ventricular heart failure. Constrictive pericarditis was diagnosed by RV pressure waveform and echocardiogram. The patients were diagnosed as PCT based on clinical symptoms, histologic findings and elevated urinary excretion levels of uroporphyrin. Even to this day, over 40% of the etiology of constrictive pericarditis remains unknown. There is a possibility of overlooking porphyria cutanea tarda in constrictive pericarditis patients. This report describes the first documented cases of familial PCT with constrictive pericarditis.

Coproporphyrins↗
PubMed1996

Thymus-related liposarcoma: report of a case and review of the literature.

We report herein the case of a 77-year-old woman who was admitted to our hospital for further evaluation of an abnormal shadow in the right upper mediastinum that had been revealed by a routine chest X-ray. Computed tomography (CT) and magnetic resonance imaging (MRI) scans confirmed the presence of a thymic tumor, but did not show any evidence of invasion into the central vessels or adjacent structures. Thus, an extended thymectomy with resection of the tumor was performed. Microscopically, normal thymic tissue was found among the tumor cells, and a pathological diagnosis of well-differentiated liposarcoma was established. From the operative and microscopic findings, it is apparent that the tumor was related to the thymus. Postoperative irradiation of 60 Gy was delivered to the operative site and the patient has remained free of disease for 29 months since the operation.

Aged↗
PubMed1996

Pulsed Doppler echocardiographic assessment of changes in pulmonary artery pressure during oxygen breathing.

To validate the use of pulsed Doppler echocardiography in detecting changes in pulmonary artery pressure (PAP), several parameters of flow velocity profiles of the right ventricular outflow tract were compared with changes in PAP and pulmonary vascular resistance measured directly by cardiac catheterization. The study was performed in 33 patients with chronic pulmonary disease (chronic obstructive pulmonary disease or pulmonary fibrosis) or pulmonary thromboembolism, during room air and 100% oxygen breathing. Inhalation of 100% oxygen for 15 min significantly reduced PAP in patients with mild pulmonary hypertension (20 < or = mean PAP < or = 24 mm Hg; control: 21.3 +/- 1.3, O2: 17.9 +/- 2.2 mm Hg, p < 0.05) and those with severe pulmonary hypertension (mean PAP > or = 25 mm Hg; control 44.9 +/- 16.8, O2: 35.4 +/- 13.5 mm Hg, p < 0.05). It also significantly reduced the pulmonary vascular resistance and cardiac output in both groups. The ratio of acceleration time to right ventricular ejection time (AT/RVET), a parameter measured by Doppler echocardiography, correlated significantly with mean PAP during room air (r = 0.73, p < 0.0001) and oxygen breathing (r = 0.64, p < 0.0001). Furthermore, AT/RVET increased significantly in patients with mild pulmonary hypertension and those with severe pulmonary hypertension. Our results suggest that the Doppler technique provides a clinically useful, noninvasive index for assessing changes in PAP during oxygen breathing in patients with pulmonary hypertension complicating chronic pulmonary disease or pulmonary thromboembolism.

Administration, Inhalation↗
PubMed1996

Coronary angiographic finding of thrombus in the left atrial appendage.

PURPOSE: The value of coronary angiography in the diagnosis of thrombus in the left atrial appendage (LAA) was retrospectively analyzed. MATERIAL AND METHODS: The study covers 34 patients in whom coronary angiography showed coronary neovascularity in LAA with coronary artery-left atrial fistula indicating LAA thrombus. All 34 patients underwent transthoracic echocardiography within one week of coronary angiography. Open-heart surgery was undertaken 2-31 months after angiography in 28 patients. RESULTS: Coronary neovascularity and coronary artery-left atrial fistula arose from the left circumflex artery in 28 patients, and from the left circumflex artery and the right coronary artery in the remaining 6 patients. By echocardiography, LAA thrombus was detected in only one of the 34 patients. In 18 of the 28 patients who underwent open-heart surgery, LAA thrombus was found at surgery to have resolved. CONCLUSION: Coronary angiography is useful in the diagnosis of LAA thrombus, and coronary neovascularity and fistula formation may indicate that the thrombus can spontaneously resolve.

Adult↗
PubMed1996

Noninvasive assessment of right heart function by 81mKr equilibrium radionuclide ventriculography in chronic pulmonary diseases.

Noninvasive multigated equilibrium radionuclide ventriculography with krypton-81m (81mKr) was used to assess right heart relaxation in patients with chronic pulmonary diseases (CPD). The subjects consisted of 30 patients with CPD and 8 patients free of cardiopulmonary diseases admitted to our department. A region of interest (ROI) was selected on both the right atrium (RA) and right ventricle (RV). A time activity curve was obtained for each ROI. As a diastolic index of the right heart performance, the right atrial early emptying rate (RAER) was obtained from the right atrial time activity curve, while the right ventricular rapid filling rate (RVRFR) was obtained from the right ventricular time activity curve. The mean RAER was significantly lower in CPD patients compared with the control (CPD, 9.5 +/- 4.5; control, 16 +/- 3.4%/100 ms). Similarly, the mean RVRFR was significantly lower in CPD patients compared with the control (CPD, 27.3 +/- 9.9; control, 34 +/- 8.5%/100 ms). A strong negative correlation was noted between the mean pulmonary arterial pressure (mPAP) and RAER (r = -0.77; p < 0.001) and between the mPAP and the RVRFR (r = -0.63; p < 0.001). Our results suggest that RAER and RVRFR measured by 81mKr are clinically useful in the noninvasive assessment of right heart relaxation in patients with CPD.

Adult↗
PubMed1996

Iodine-123-metaiodobenzylguanidine myocardial imaging in patients with right ventricular pressure overload.

UNLABELLED: Iodine-123-metaiodobenzylguanidine ([123I]MIBG) has been used to evaluate the cardiac sympathetic nervous system, particularly that of the left heart. To clarify whether the right ventricular (RV) sympathetic neuronal function could be evaluated by [123I]MIBG myocardial imaging, we applied the technique in patients with pulmonary hypertension that was associated with either chronic pulmonary diseases or pulmonary vascular diseases. METHODS: All patients underwent right heart catheterization, and right heart hemodynamics were determined during a clinically stable state. SPECT was performed in the resting state 15 min (early imaging) and 4 hr (delayed imaging) postadministration of [123I]MIBG. Seven regions of interest (ROI) were selected on the delayed short-axis images on the RV free wall, left ventricular (LV) free wall and interventricular septum (IVS). We calculated the IVS-to-LV uptake ratio from the scintillation counts of the ROI. Thallium-201 myocardial imaging was also performed within 1 wk after [123I]MIBG imaging. RESULTS: Images obtained with these techniques were analyzed for the RV-to-LV uptake ratio. The IVS-to-LV ratio on [123I]MIBG correlated negatively and significantly with the mean pulmonary arterial pressure (PAm). The RV-to-LV uptake ratio on 201Tl images correlated significantly with PAm. CONCLUSION: Our results suggest that the uptake ratio of [123I]MIBG in the IVS is a useful index for evaluating the severity of pulmonary hypertension, and that chronic RV pressure overload contributes to disturbances of the cardiac sympathetic nervous system.

3-Iodobenzylguanidine↗
PubMed1995

Effects of nicorandil on kinetics of oxygen uptake at the onset of exercise in patients with coronary artery disease.

The beneficial effects of coronary vasodilators on exercise capacity in patients with angina pectoris are well known. However, their effects on oxygen uptake (VO2) kinetics at the onset of exercise have not been elucidated. The present study was undertaken to determine the acute effects of nicorandil, a newer coronary vasodilator, on the kinetics of VO2 at the onset of exercise in patients with ischemic heart disease. Ten patients with significant coronary stenosis performed constant mild-intensity cycle exercise (32 +/- 3 W) for 6 minutes after oral administration of 10 mg of nicorandil or an identical placebo in a double-blind, crossover manner. Nicorandil had no effect on resting heart rate, blood pressure, or VO2. However, the time constant for the increase in VO2 during constant work rate exercise was significantly shorter (the kinetics of VO2 were faster) after administration of nicorandil than after placebo (46.5 +/- 13.3 vs 51.1 +/- 11.9 seconds; p = 0.039). The increase in VO2 at 6 minutes compared with 3 minutes of constant work, which reflects the VO2 kinetics, also was reduced with nicorandil (3.8 +/- 37.9 vs 27.5 +/- 27.1 ml/min; p = 0.022). Nicorandil was found to increase the rate of VO2, increase during the onset of constant work rate exercise, probably as a result of an improved response in cardiac output. Analysis of VO2 kinetics provides new and useful parameters for the evaluation of circulatory adjustments at the onset of exercise in patients with ischemic heart disease.

Adult↗
PubMed1995

Ventilatory and pulmonary vascular responses to acute hypoxia are nonuniform in healthy man.

The present study was undertaken to examine the pulmonary vascular and ventilatory responses to acute hypoxia in healthy individuals. Pulmonary hemodynamics and minute ventilation (VE) were serially measured during inhalation of 13% O2 for 15 min. There was a wide variability in the pulmonary vascular response to acute hypoxia, and a significant negative correlation between the initial increase in VE after the start of hypoxia (delta VE) and the percent increase in mean pulmonary arterial pressure (r = -0.646; p < 0.01). The fall in arterial oxygen tension significantly decreased in response to an increase in delta VE. These results support the view that a blunted ventilatory response to acute hypoxic stimulation enhances alveolar hypoxia, thereby favoring the constriction of pulmonary vasculature. Thus, our results suggest that the ventilatory response to acute hypoxia plays a significant role in the pulmonary vascular response to acute hypoxia.

Acute Disease↗
PubMed1995

Assessment of right ventricular diastolic function by pulsed Doppler echocardiography in chronic pulmonary disease and pulmonary thromboembolism.

We evaluated right ventricular (RV) diastolic performance in 12 healthy subjects (control), 25 patients with chronic pulmonary diseases (CPD) and 6 patients with chronic pulmonary thromboembolism (PTE). Flow velocity patterns were determined by the pulsed Doppler technique. The values determined included acceleration time (AT), deceleration time (DT), and the ratio of the atrial contraction wave (A) to the rapid filling wave (R) (A/R ratio) from flow velocity patterns in the RV inflow tract. DT was significantly prolonged in the CPD and PTE groups compared with the control group, indicating dysfunction during the early (middle) filling period. The prolongation was marked in those patients with pulmonary hypertension. The A/R ratio was significantly higher in the CPD and PTE groups than in the control group, indicating a decrease in RV compliance. The A/R ratio increased slightly with the increase in the end-diastolic volume index. These results suggested that the pressure overload plays an important role in RV diastolic dysfunction in patients with pulmonary disease, and that preload contributes to the dysfunction.

Aged↗
PubMed1995

Interpretation of extravascular thermal volume of the lung in patients with chronic pulmonary diseases.

To understand the significance of measured extravascular thermal volume of the lung (ETVL) in chronic pulmonary diseases, we measured ETVL using the double-indicator dilution technique in 17 emphysematous patients and 15 patients with pulmonary fibrosis. The level of ETVL in emphysema is significantly correlated with parameters reflecting the severity of the disease, including FEV1.0% (r = 0.54, p < 0.05), DLCO/VA (r = 0.54, p < 0.05), PaO2 (r = 0.61, p < 0.01), and mean pulmonary artery pressure (r = -0.61, p < 0.01). In pulmonary fibrosis, a significant inverse correlation was found between ETVL and PaO2 (r = -0.64, p < 0.02), DLCO/VA (r = -0.58, p < 0.05), and %VC (r = -0.61, p < 0.02). The mean level of ETVL in both groups of patients was lower than previously reported normal values. These results suggest that ETVL may reflect the decrease in pulmonary vasculature in emphysematous patients, while it may signify a decrease of pulmonary vasculature and increased volume of pulmonary interstitial tissue surrounding the pulmonary vasculature in pulmonary fibrosis. We conclude that ETVL may represent a good estimate of the condition of the pulmonary vasculature and interstitial tissue volume in patients with chronic pulmonary diseases.

Aged↗