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Biomedical subjects

M Inada

Publications and source records attributed to M Inada.

At least 163 records · Page 9Linked to original sources
PubMed1994

Effect of body characteristics on the variables of signal-averaged electrocardiograms in healthy subjects.

Late potentials have been reported to be affected by body size or left ventricular mass. To our knowledge, however, the effect of subadipose tissue, which is known to influence QRS amplitudes of the surface ECG on the variables of late potentials, has not been evaluated. The relationships between the variables of late potentials and various obesity indices were assessed in 45 men, aged 24 to 38 years, without structural heart disease and bundle branch blocks. QRS duration (DUR), root mean square voltage in the last 40 ms (RMS), and low-amplitude signals < 40 microV (LAS) were obtained by signal-averaged ECG. Left ventricular mass (LV mass) was determined by echocardiography. The DUR and RMS had no correlation with body height, weight, body mass index (BMI), sum of skin folds (triceps and subscapular), or LV mass. Positive linear correlations were found between LAS and weight (r = 0.48, p < 0.002), BMI (r = 0.54, p < 0.002), sum of skin folds (r = 0.57, p < 0.002), and percent BMI (r = 0.54, p < 0.002). Subadipose tissue may shift the onset of the 40-microV point of LAS to the left with a consequent prolongation of LAS by attenuation of the QRS complex. These data suggest that the use of LAS alone or as a combination in an obese population for the definition of positive late potentials is inappropriate.

Adult↗
PubMed1994

Prolonged survival in a patient with a single ventricle without pulmonary stenosis.

Prolonged survival of the patient with a single ventricle is rare. We report the case of a 57-year-old man who has type A3 of Van Praagh's classification of single ventricle with pulmonary hypertension without pulmonary stenosis. Favorable streaming, a large bulboventricular foramen, and intact atrioventricular valves may have contributed to his long-term survival.

Echocardiography, Transesophageal↗
PubMed1993

Regulatory elements that mediate expression of the gene for the angiotensin II type 1a receptor for the rat.

To analyze the mechanism of the cell type-specific expression of rat angiotensin II type 1a receptor (AT1a-R) gene, we isolated the 5'-portion of the gene and identified multiple positive and negative regulatory sequences that regulate its transcription. Primer extension and S1 mapping identified a transcriptional initiation site at 33 (position +1) base pairs (bp) downstream of TATA sequence. The transcriptional activities of various 5'-deletion mutants of the AT1a-R gene upstream region, fused to the chloramphenicol acetyltransferase (CAT) gene, were examined using rat vascular smooth muscle cells (A10) and glial cells expressing AT1a-R mRNA predominantly or PC12 cells expressing AT2-R and very small amounts of AT1a-R mRNA. A 980-bp 5'-flanking sequence contained at least three positive elements, P1 (-560 to -489), P2 (-331 to -201), and P3 (-201 to -61). P1 and P3 were active in the tested three cells, and P2 was functional only in glial and PC12 cells. In addition to these positive elements, there was negative element, N1 (-489 to -331), which was active only in PC12 cells. These elements, when cotransfected with the AT1a-CAT fusion gene, had competitive effects against its promoter activity. The present study suggests the presence of multiple trans-acting factors that act on these positive and negative cis-acting elements and regulate the cell type-specific expression of the rat AT1a-R gene.

Animals↗
PubMed1993

Two novel mutations in the vasopressin V2 receptor gene in unrelated Japanese kindreds with nephrogenic diabetes insipidus.

Nephrogenic diabetes insipidus (NDI) is a rare X-linked disorder exhibiting renal resistance to the antidiuretic action of arginine vasopressin (AVP). Recent elucidation of the vasopressin V2 (renal type) receptor gene structure has enabled us to test the hypothesis that the genetic defect in the V2 receptor is the likely molecular basis of NDI. By using the polymerase chain reaction (PCR)-direct sequencing, we identified novel V2 receptor gene mutations in two unrelated Japanese kindreds with NDI. In the male patients of kindred A, a single codon deletion in one of two consecutive GTC triplets (nucleotide 832 to 837) was detected. This base change resulted in the loss of a valine residue in the 6th transmembrane domain. In the affected males of kindred B, a G to C substitution was found at nucleotide 428, altering codon 143 from arginine (CGT) to proline (CCT) in the second cytoplasmic domain. PCR-single strand conformation polymorphism (SSCP) analysis of family members demonstrated that the mutations cosegregated with clinically affected individuals and were absent in normal subjects. Our results suggest that different V2 receptor defects could be responsible for AVP resistance in individual NDI kindreds.

Adult↗
PubMed1993

Disturbance of pulmonary gas exchange in patients with acute myocardial infarction-associated pericardial effusion.

To elucidate the effect of pericardial effusion on pulmonary gas exchange in patients with infarction-associated pericardial effusion, 294 consecutive patients with their first Q-wave anterior wall acute myocardial infarction were examined carefully by echocardiography, chest radiography and hemodynamic monitoring. A pericardial effusion was detected in 77 patients and was absent in 217 (group 1). Of the 77 patients with pericardial effusion, it was mild in 57 (group 2) and moderate in 20 (group 3). Patients with pericardial effusion (groups 2 and 3) had significantly greater pulmonary artery wedge pressure and more left ventricular segments with advanced asynergy than did those in group 1. Although there were no significant differences in pulmonary artery wedge pressure and number of left ventricular segments with advanced asynergy between groups 2 and 3, group 3 had significantly greater right atrial pressure, alveolar arterial oxygen difference and incidence of high radiographic score. Thus, accumulation of pericardial effusion to a moderate amount may contribute to the greater incidence of increase in extravascular lung water, and disturbance of pulmonary gas exchange.

Aged↗
PubMed1993

[Thyroid hormone metabolism].

Most thyroxine (T4) secreted from the thyroid is deiodinated in peripheral tissues. At least three isozymes are known in iodothyronine deiodinase which catalyzes the conversion of T4 to triiodothyronine (T3) or reverse T3. Type I 5'-deiodinase (5'D-I) exists in most tissues including the liver, kidney and thyroid. Type II 5'-deiodinase (5'D-II) which exists mainly in the brain, pituitary, brown fat and placenta plays an important role in the saturation of intracellular T3 receptor. Type III enzyme (D-III) which deiodinases the five positions of T3 is considered to modulate the T3 content by regulating its degradation. The complementary DNA (cDNA) for the rat and human 5'D-I has recently been cloned. 5'D-I contains a rare amino acid selenocysteine, which is essential for normal deiodinative function in humans as well as rats. On the other hand, 5'D-II, whose molecular weight is much heavier than that of 5'D-I, does not contain selenocysteine and its cDNA has not been sequenced. Little is known about the molecular characteristics of D-III. Further studies are needed to clarify the molecular mechanism by which deiodinase proteins are produced in various circumstances and to investigate the meticulous aspects of metabolic pathways other than deiodination.

Adipose Tissue, Brown↗
PubMed1993

Precordial ST segment depression in patients with Q wave inferior myocardial infarction: role of infarction-associated pericarditis.

To examine the diagnostic significance of precordial ST segment depression in Q wave inferior myocardial infarction, 157 consecutive patients were examined carefully by means of auscultation, ECG, and two-dimensional echocardiography. Precordial ST segment depression was transient (lasting < 72 hours from the onset of myocardial infarction) in 63 patients and persistent (> or = 72 hours) in 40. Twenty-eight patients with persistent, 19 patients with transient, and 14 patients without precordial ST segment depression had advanced asynergy (akinesia or dyskinesia) in the posterior segments, whereas 13 patients with persistent, six with transient, and six without precordial ST segment depression had pericardial rub. Patients with persistent precordial ST segment depression had a significantly higher incidence of severe wall motion abnormality (p < 0.01) and inflammation (p < 0.05) of the posterior wall than the other two groups. In 5 of 40 patients with persistent ST segment depression, pericardial rub was detected in the absence of advanced asynergy in the posterior segments. Although not highly sensitive, persistent precordial ST segment depression appeared to be a fairly specific indicator (specificity 92%) of concomitant posterior involvement with severe wall motion abnormality, inflammation, or both.

Aged↗
PubMed1993

Effect of sex on left ventricular pump function in patients with anterior wall myocardial infarction treated with primary angioplasty.

BACKGROUND: The prognosis of acute myocardial infarction (AMI) is distinctly worse in postmenopausal women than in age-matched men. Unstable angina before AMI is reported to protect left ventricular pump function during the left ventricular remodeling process in patients who have undergone successful percutaneous transluminal coronary angioplasty (PTCA). We postulate that left ventricular pump function may be different in postmenopausal women and age-matched men with unstable angina before AMI and successful PTCA. METHODS: Twenty-three postmenopausal women (aged 63 +/- 7 years) and 31 age-matched men (aged 65 +/- 6 years) with unstable angina before AMI and successful PTCA were investigated using radionuclide angiography in the late hospital phase. RESULTS: Global ejection fraction (EF), regional EF of the non-infarcted area, and the ratio of systemic arterial systolic blood pressure to left ventricular end-systolic volume (P:V ratio) were lower in women compared with those in men. Global EF, regional EF of the non-infarcted area, and the P:V ratio in women with left ventricular end-diastolic volume (EDV) > or = 140 ml were significantly lower than in those with a left ventricular EDV of less than 140 ml, but no significant differences were noted in these indexes with regard to left ventricular EDV in men. CONCLUSION: Sex may play an important role in the left ventricular remodeling process in postmenopausal women, especially those with a dilated left ventricle.

Aged↗
PubMed1993

Effect of subadipose tissue on the variables of signal-averaged electrocardiograms in healthy subjects.

Ventricular late potentials are obtained by signal averaging of surface electrocardiograms. Late potentials have been reported to be affected by body size or left ventricular mass. However, the effect of subadipose tissue, which is known to influence QRS amplitudes of surface ECG, on the variables of late potentials has not been evaluated. The relationships between the variables of late potentials and various obesity indices were assessed in 45 men, aged 24-38 years, without structural heart disease and bundle branch blocks. QRS duration, root mean square voltage in the last 40 ms and low-amplitude signals < 40 microV were obtained by signal-averaged ECG. Left ventricular mass was determined by echocardiography. QRS duration and root mean square voltage had no correlation with body height, weight, body mass index, sum of skin folds (triceps and subscapular) or left ventricular mass. Positive linear correlations were found between low-amplitude signals and weight (r = 0.48, p < 0.002) body mass index (r = 0.54, p < 0.002), sum of skin folds (r = 0.57, p < 0.002), percent body mass index (r = 0.54, p < 0.002). Subadipose tissue may shift the onset of the 40-microV point of low-amplitude signals to the left with a consequent prolongation of low-amplitude signals by attenuation of the QRS complex. These data suggest that the use of low-amplitude signals alone or as a combination in an obese population for the definition of positive late potentials is inappropriate. The low-amplitude signal has to be used with caution in obese patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1993

Increase in left ventricular ejection rate during recovery from exercise in patients with myocardial infarction.

Changes in left ventricular (LV) ejection rate were evaluated during supine bicycle exercise and recovery in 12 patients with anterior myocardial infarction. Pulmonary artery wedge pressure (34 +/- 9 to 14 +/- 5 mm Hg) and plasma norepinephrine level decreased at 2 min recovery from peak exercise, whereas plasma lactate tended to increase. As a result, LV ejection rate reached the highest value at 2 min of recovery. Thus, both cardiac (optimal filling pressure) and peripheral factors (reduced vascular resistance) caused the increase in LV ejection rate at early recovery.

Acid-Base Equilibrium↗
PubMed1993

Left ventricular function during exercise after aortic valve replacement.

To evaluate the difference in left ventricular function during exercise after successful aortic valve replacement, left ventricular function was investigated using radionuclide angiography in 12 patients with normal resting left ventricular systolic function. Patients were divided into two groups: Group 1 was comprised of 5 patients after aortic valve replacement for aortic stenosis and group 2 was comprised of 7 patients for aortic insufficiency. Left ventricular ejection fraction increased significantly during exercise in both groups. The increase in systolic arterial pressure to left ventricular end-systolic volume was significantly larger in group 1 than group 2, whereas the increase in left ventricular end-diastolic volume was significantly larger in group 2 than group 1. Thus, increase in left ventricular contractility played an important role in regulating increased left ventricular ejection fraction during exercise in patients with aortic prostheses for aortic stenosis, whereas increase in left ventricular end-diastolic volume played an important role in patients with aortic prostheses for aortic insufficiency.

Adult↗
PubMed1993

Effect of body characteristics on the variables of signal-averaged electrocardiogram in healthy teenage subjects.

Ventricular late potentials are obtained by signal-averaged surface electrocardiography. Late potentials have been reported to be affected by body characteristics or left ventricular mass. To evaluate late potentials in relation to body characteristics, 52 healthy Japanese young volunteers (21 girls, 31 boys) aged 15-16 years were studied. QRS duration in men was significantly longer than in women. There were no significant differences in low-amplitude signal and root mean square voltage between women and men. When relations between signal-averaged electrocardiographic parameters and body characteristics were examined, QRS duration had positive linear correlations with weight and body mass index. The slope of QRS duration and weight relation, and QRS duration and body mass index relation was significantly steeper in men compared to those in women; a prolongation of QRS duration in men compared to women as weight and body mass index increased. Our results indicated that QRS duration in teenage healthy subjects should be used with caution because it is affected by gender.

Adolescent↗
PubMed1993

Ventriculoarterial coupling during low-level exercise testing after myocardial infarction.

To evaluate the change of ventriculoarterial coupling during low-level exercise in patients after myocardial infarction, the ratio of systolic blood pressure to left ventricular end-systolic volume (P/V ratio) and the ratio of systolic blood pressure to stroke volume (effective arterial elastance) were investigated using radionuclide angiography in 73 consecutive patients with a negative predischarge exercise test. The patients were divided into three groups according to their resting left ventricular ejection fraction: group A (n = 12) > or = 60%; group B (n = 32) 41-59%; group C (n = 29) < or = 40%. The ejection fraction increased significantly during exercise in all three groups. There was no significant difference in the change of the P/V ratio during exercise between groups A and B, but it was significantly smaller in group C. The effective arterial elastance increased during exercise in group A, did not change in group B, and decreased in group C. Thus, the augmentation of myocardial contractility was an important factor related to the increase in ejection fraction during exercise in patients with normal or slightly reduced cardiac function, whereas the decrease in effective arterial elastance was important in patients with poor cardiac function.

Adult↗
PubMed1993

Left ventricular diastolic filling properties in diabetic patients during isometric exercise.

Left ventricular diastolic filling properties during isometric handgrip exercise were measured by pulsed Doppler echocardiography in 33 noninsulin-dependent diabetic patients with a normal ejection fraction and 15 control subjects. Diabetic patients were subdivided into two groups according to their resting left ventricular filling pattern (A/E): 18 patients were in group DM-1 (A/E < or = 1.1) and 15 patients were in group DM-2 (A/E > 1.1). At rest, A/E ratio and A wave were higher, and deceleration half-time was longer in group DM-2 than in normal subjects and group DM-1, but there was no significant difference between normal subjects and group DM-1. The A/E ratio increased significantly in all three groups during isometric handgrip exercise. However, the change in A/E from rest to peak exercise in group DM-1 (0.29 +/- 0.20) was significantly greater than in normal subjects (0.09 +/- 0.07). These results suggest that diabetes mellitus patients with normal resting left ventricular (LV) filling pattern (group DM-1) had LV diastolic filling abnormalities with isometric handgrip exercise. Doppler echocardiography with isometric handgrip exercise is useful in identifying underlying left ventricular diastolic dysfunction in diabetic patients.

Diabetes Mellitus, Type 2↗
PubMed1993

Rat angiotensin II (type 1A) receptor mRNA regulation and subtype expression in myocardial growth and hypertrophy.

Two subtypes of angiotensin II (Ang II) receptors (AT1 and AT2) are distinguished by using the respective specific antagonists. In the present study, we report the regulation of cardiac AT1 type A (AT1A) receptor mRNA levels and the expression pattern of AT1 and AT2 receptors in the growth of the heart and the development and regression of cardiac hypertrophy. The ventricular AT1A mRNA level and the density of Ang II receptors at the neonatal period were significantly increased (3.5-fold and 2.5-fold, respectively) and then downregulated with maturation. The cardiac hypertrophy established in spontaneously hypertensive rats or two-kidney one-clip renovascular hypertensive rats resulted in substantial increases in ventricular AT1A mRNA levels (threefold) and Ang II receptor densities (twofold) as compared with those in respective control rats, whereas the receptor affinity was similar. The proportion of AT1 and AT2 subtypes in the specific Ang II binding in ventricular membranes prepared from normal adult rats was nearly equal. This proportion did not change significantly in the development of myocardial hypertrophy. The regression of cardiac hypertrophy by the normalization of elevated blood pressure completely reversed the increased levels of AT1A mRNA and the receptor density to the control level. Thus, AT1 and AT2 receptors are present in rat ventricular myocardium, and their expression is developmentally regulated and upregulated in response to hypertrophic change. Ang II action exerted through the increased number of Ang II receptors may contribute to the growth of the heart and thus to the maintenance of established hypertrophy as one of the hormones involved in hypertrophy development.

Angiotensin II↗
PubMed1993

Shaker-related potassium channel, Kv1.4, mRNA regulation in cultured rat heart myocytes and differential expression of Kv1.4 and Kv1.5 genes in myocardial development and hypertrophy.

The multiple K+ channels are crucial for repolarization and configuration of the action potential in the neuronal and cardiac cells. In this study, we report the regulatory mechanisms of rapidly inactivating Shaker Kv1.4 channel transcript in the rat heart. Quantitative PCR analysis showed that stimulation with high concentration of KCl, BAY-K 8644, or 12-O-tetradecanoyl phorbol-13-acetate resulted in an immediate and substantial increase (two- to threefold) of Kv1.4 mRNA levels in spontaneously beating myocytes prepared from neonatal rat ventricles. The Kv1.4 mRNA in the ventricle remains at a steady state level after birth and gradually declines with maturation. These results suggest that the Kv1.4 mRNA level is not static and undergoes dynamic modulation by multiple factors that activate intracellular signals. In addition, the expression patterns of Kv1.4 as well as the delayed rectifier Shaker K+ channel Kv1.5 mRNAs were examined in hypertrophied ventricles in which a plateau phase of action potential is remarkably prolonged. The Kv1.5 mRNA level was dramatically repressed while the Kv1.4 mRNA level was remarkably increased. This differential regulation was completely reversed by the normalization of hypertrophy, suggesting that the pathological alterations of K+ channel gene regulation may be involved in the occurrence of ventricular arrhythmias in hypertrophic hearts.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1993

Mononuclear cell infiltration and its relation to the expression of major histocompatibility complex antigens and adhesion molecules in pancreas biopsy specimens from newly diagnosed insulin-dependent diabetes mellitus patients.

We examined pancreas biopsy specimens from 18 newly diagnosed insulin-dependent diabetes mellitus (IDDM) patients to elucidate the mechanism underlying beta cell destruction. Pancreas islets were seen in all patients and insulitis in eight patients. Infiltrating mononuclear cells consisted of CD4+T, CD8+T, B lymphocytes, and macrophages. Among them, CD8+T lymphocytes were predominant and macrophages followed. The expression of MHC class I antigens was increased in islet and endothelial cells in nine patients. MHC class II expression was increased in endothelial cells of the same patients. The expression of intercellular adhesion molecule-1 was increased in endothelial cells in two of the nine patients with MHC hyperexpression; in one of them, lymphocyte function-associated antigen-3 expression was also increased. Out of the eight patients with insulitis, seven showed MHC class I hyper-expression, whereas 2 of the 10 patients without insulitis showed the phenomenon (P < 0.05). The relation between insulitis and the hyperexpression of adhesion molecules was not evident. In conclusion, we revealed the close relation between CD8+T lymphocyte-predominant insulitis and MHC class I hyperexpression in islet cells. This suggests that infiltrating CD8+T lymphocytes recognize islet autoantigens in association with increased MHC class I molecules and act as major effector cells in autoimmune response against islet cells in IDDM pancreases. The role of adhesion molecules in the pathogenesis of IDDM still remains to be elucidated.

Adolescent↗