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Biomedical subjects

M Inada

Publications and source records attributed to M Inada.

At least 307 records · Page 17Linked to original sources
PubMed1988

Effect of ammonia on the gastric mucosa in rats: pathophysiological importance of urease in gastric ulcer disease.

We examined the pathophysiological roles of the urea-urease-ammonia system in gastric ulcer disease using rats. Exposure of the stomach to ammonia (0.01-1.0%) decreased the transmucosal potential difference (PD) and histological injury in a concentration-dependent manner. Exposure of the stomach for 20 min to urea (0.025-0.2%) together with urease (100 IU) produced a decrease in PD and microscopic injury similarly, and the lesion was closely associated with the amount of ammonia produced. Urea and urease alone had no effect on the gastric mucosa. These results suggested the pathophysiological importance of urea, urease and ammonia in gastric ulcer disease.

Ammonia↗
PubMed1988

Relationship among thyrotropin (TSH), thyroid stimulating immunoglobulins, and results of triiodothyronine (T3) suppression test in patients with Graves' disease.

To investigate the relationship between TSH and abnormal thyroid stimulator(s) in patients with hyperthyroid Graves' disease in whom normal thyroid hormone levels in the serum were maintained by antithyroid drug therapy and in patients with euthyroid Graves' disease, determinations were made of the TSH concentration, action of thyroid stimulating immunoglobulins (TSAb and TBII), and T3 suppression. Out of thirty-three patients with hyperthyroid Graves' disease, twelve patients with subnormal TSH levels were all non-suppressible according to the T3 suppression test results and the detectability of TSAb and/or TBII was as high as 75%. In three out of five patients with euthyroid Graves' disease, the serum TSH level was subnormal. All three showed non-suppressibility in the T3 suppression test and positive action of either TSAb or TBII. One of them became clinically thyrotoxic when the TSAb activity was further increased and TBII became positive, and was therefore diagnosed as having hyperthyroid Graves' disease. The present findings suggest that there are still abnormal thyroid stimulator(s) in patients with hyperthyroid Graves' disease who have low TSH, even if their thyroid hormone concentrations remain normal. Moreover, it is likely that some of the patients with euthyroid Graves' disease are actually in a state of subclinical hyperthyroidism because of the presence of abnormal thyroid stimulator(s).

Adolescent↗
PubMed1988

Differential effects of dibutyryl cyclic adenosine monophosphate and simple sugars on NK and LAK activities suggesting differences of their cytotoxic mechanism.

The increase of intracellular cyclic AMP levels suppresses the cytotoxic activities of lymphocytes and monosaccharides interfere with cell to cell and cell to cytokine interactions, and these effects on natural killer (NK)/antibody-dependent cell-mediated cytotoxicity (ADCC) and lymphokine activated killer (LAK) activities were examined. Dibutyryl cyclic AMP markedly suppressed NK, IL-2-augmented NK and ADCC activities in a dose-dependent manner but not previously induced LAK activity. Induction of LAK was inhibited. Dibutyryl cyclic GMP had no effect. Addition of mannose 6-phosphate and galactose 6-phosphate strongly inhibited NK and ADCC activities, but not LAK activity. These results suggest that the lytic mechanism for NK and ADCC activity is different from that of LAK activity.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1988

[Hemodynamic response to diurnal activities of patients with myocardial infarction evaluated by ambulatory monitoring of systolic time intervals using ear densitography].

The purpose of this study was (1) to assess the hemodynamic changes during daily activities by 24-hour continuous ear-densitographic monitoring (Holter EDG) in 14 patients with acute myocardial infarction (MI), and (2) to define the changes in left ventricular performance during and after acute upright posture in 35 patients with old MI. Ninety-seven percent of the daily activities could be reliably measured by ambulatory monitoring of systolic time intervals (STI) and the most significant change in STI was observed during defecation. The ratio of preejection period to left ventricular ejection time (PEP/LVET) increased significantly during defecation (0.42 +- 0.09----0.50 +- 0.09, p less than 0.05), but heart rate either increased (5 patients) or decreased (4 patients). Though there was no change in PEP/LVET during sleep, walking and washing the face and hands, it tended to increase during eating and urinating. Acute upright posture caused sudden acceleration of the heart rate, and increased PEP/LVET immediately (0.36 +- 0.05----0.39 +- 0.06, p less than 0.005). The latter further increased immediately after sitting (0.36 +- 0.05----0.41 +- 0.07, p less than 0.001) and 1 min after sitting (0.36 +- 0.05----0.43 +- 0.07, p less than 0.001), but it was stable thereafter. Thus, abrupt changes in these parameters indicate that changes both in neural activity and venous return are virtually instantaneous. We concluded that the Holter EDG will facilitate the evaluation of daily activities of patients, and that the information obtained in this study could be valuable in understanding the physiology and hemodynamics of patients recovering from acute MI.

Activities of Daily Living↗
PubMed1988

[Infarct size related to the distribution and site of coronary artery lesions studied by the unfolded map technique using single photon emission computed tomography].

To assess the relative importance of the anatomical characteristics of the coronary artery distribution and the sites of the arterial stenoses in relation to infarct size, 21 patients with old myocardial infarction and angiographically-proven 90% or greater stenoses (AHA classification) of one of the major coronary arteries were studied. The infarct size was evaluated by a new quantitative method, the unfolded map, derived from single photon emission computed tomography (SPECT). Eleven patients had right coronary artery disease (Group RCA: segment 1; five patients and segment 2; six patients). Seven patients who had the large left anterior descending artery (LAD) which was distributed to the inferior portion of the apical area were defined as Small R, and four patients with large RCA as Large R. Ten patients each had a significant stenosis in the LAD (Group LAD: segment 6; six patients and segment 7; four patients). Four patients with significant stenosis proximal to segment 9 were defined as Pre-9, and seven patients with stenosis distal to the segment, as Post-9. Stress T1-201 scintigraphy with SPECT was performed and the unfolded map was obtained with data of the maximal count circumferential profiles in the redistribution image. Infarction was defined as a defect below 55% of the standard value. The necrotic area ratio expressed as percentage of the defect area to the entire map area was calculated and used as the indicator of infarct size. Although there was no significant difference in the necrotic area ratio between segment 1 and 2 lesions. Large R had the significantly larger necrotic area ratios (24.9 +- 4.6%) than did Small R (9.7 +- 4.4%; p less than 0.01). In the Group LAD, there was no significant difference in the necrotic area ratio between segment 6 and 7 lesions, but Pre-9 had the larger ratio (30.4 +- 3.3%) than did Post-9 (15.4 +- 7.7%; p less than 0.01). These data suggest that the factors related to infarct size are either the distribution of the coronary arteries in the apical area in the Group RCA or the sites of the stenotic lesions relative to the branching portion of the first diagonal branch in the Group LAD.

Adult↗
PubMed1988

The factors associated with fascicular block in acute anteroseptal infarction.

To elucidate the genesis and effect of fascicular block, 131 patients with acute Q-wave anteroseptal infarction were studied. Thirty-seven patients had new onset of fascicular block in the coronary care unit. The hospital mortality rate was 16%. Multivariate analysis was performed to determine the important variables related to the occurrence of fascicular block and hospital mortality based on 17 clinical variables obtained at the time of hospital admission. Serum potassium level and heart rate were the significant factors predicting the occurrence of fascicular block, whereas cardiac output and arterial oxygen tension were important for hospital mortality. Therefore, not only the rise in the heart rate but also the effect of the serum potassium level on the conduction system are independent factors related to the occurrence of fascicular block, and fascicular block in itself has no significant influence on the hospital mortality.

Aged↗
PubMed1987

Ventricular myocytes from neonatal rats are more responsive to dexamethasone than atrial myocytes in synthesis of atrial natriuretic peptide.

Using the primary culture of neonatal rat ventricular myocytes, synthesis and secretion of rat atrial natriuretic peptide (rANP) were studied. Ventricular myocytes in culture, although contained less amounts of cellular immunoreactive (IR)-rANP, secreted substantial amounts of IR-rANP at a rate comparable to that of atrial myocytes. Dexamethasone markedly stimulated synthesis and secretion of IR-rANP by cultured ventricular myocytes in a dose-dependent manner (10(-10)-10(-6) M), of which effect was far more potent than that in atrial myocytes. Testosterone and triiodothyronine also stimulated synthesis and secretion of ventricular IR-rANP to the extent comparable to that of atrial IR-rANP. The present study suggests that tissue-dependent difference in glucocorticoids sensitivity plays an important role in the regulation of developmental ANP gene expression in mammalian heart.

Age Factors↗
PubMed1987

Role of atrial natriuretic polypeptides for exaggerated natriuresis in essential hypertension.

Eighteen patients with essential hypertension were separated into 2 groups, renin-unresponsive and renin-responsive, on the basis of their plasma renin response when challenged by furosemide and upright posture. The response to acute infusion of hypertonic saline solution (1.4% saline solution at a rate of 0.3 ml/min/kg over 60 minutes) was then studied. In the renin-unresponsive group, peak rate of fractional excretion of sodium and peak urine flow after saline loading were 7.6 +/- 0.7% and 476 +/- 34 ml/hour, respectively, and peak value of atrial natriuretic polypeptides (ANP) was 784 +/- 140 pg/ml. In the renin-responsive group, the values were 3.1 +/- 0.4%, 194 +/- 29 ml/hour and 115 +/- 33 pg/ml. Both fractional excretion of sodium, urine flow and ANP response were significantly higher (p less than 0.01) in the renin-unresponsive group. Moreover, a highly significant relation (r = 0.82, p less than 0.01) was observed between fractional excretion of sodium and ANP levels in all hypertensive patients. The degree of saline-induced natriuresis was not related to blood pressure, heart rate, endogenous creatinine clearance, antidiuretic hormone or preexisting level of aldosterone. Plasma renin activity changed little in either group during saline infusion, but tended to be higher at all times in the renin-responsive patients. The present findings suggest that the enhanced secretion of ANP is an important determinant for exaggerated natriuresis observed in patients with renin-unresponsive hypertension.

Adult↗
PubMed1987

Effects of steroid and thyroid hormones on synthesis of atrial natriuretic peptide by cultured atrial myocytes of rat.

The in vitro effects of various steroid and thyroid hormones on synthesis of rat atrial natriuretic peptide (rANP) were studied using new-born rat atrial myocytes in culture. Dexamethasone, testosterone and triiodothyronine markedly stimulated both synthesis and secretion of immunoreactive (IR)-rANP with the same peak after 4-day-culture. Dexamethasone and testosterone dose-dependently (10(-7)-10(-6) M) stimulated synthesis of IR-rANP and were the most potent among various steroids tested. Triiodothyronine (T3) also stimulated synthesis of IR-rANP in a dose-dependent manner (10(-8)-10(-7) M), of which effect was more potent than that of tetraiodothyronine, whereas reverse T3 was ineffective. The present study clearly shows that glucocorticoids, androgens and thyroid hormones directly stimulate synthesis of ANP by atrial myocytes and suggests that ANP may play a potential role in mediating and/or modulating the biological effects by these hormones in the cardiovascular system.

Adrenal Cortex Hormones↗
PubMed1987

Effect of exercise on ventricular diastolic time in coronary artery disease.

To evaluate diastolic time during uninterrupted upright exercise, 28 normal volunteers (group 1) and 12 men with coronary artery disease (group 2) were studied by ear densitography. Electromechanical systole-heart rate and diastolic time-heart rate regression equations during upright exercise were obtained from group 1. Electromechanical systole-heart rate had an inverse linear relation (electromechanical systole = 480 - 1.4 heart rate) and diastolic time-heart rate had an inverse nonlinear relation (diastolic time = 1206e-0.02 heart rate). Although there were no significant differences in electromechanical systole and diastolic time at 1 minute of exercise between patients with and without CAD, at peak exercise prolongation of electromechanical systole and consequent shortening of diastolic time in patients with CAD were observed. This disproportionate shortening of diastole with lengthening of systole at peak exercise tends to decrease myocardial perfusion and, hence, oxygen supply, while increasing myocardial oxygen demand, contributing to aggravation of ischemia in patients with CAD.

Coronary Disease↗
PubMed1987

Immunohistochemical distribution of vitamin B12 R-binder in renal cell carcinoma.

Renal cell carcinomas and normal kidney tissues were examined for the expression of vitamin B12 R-binder by the indirect immunoperoxidase method. In normal kidney tissue, the presence of the vitamin B12 R-binder was shown to be confined to the straight portion (pars recta) of proximal tubules. Seven of the 38 cases of renal cell carcinoma (18%) expressed the vitamin B12 R-binder antigen. This provides a further evidence of the proximal tubular nature of renal cell carcinoma, and suggests that a small proportion of renal cell carcinomas originate from the straight portion of the renal proximal tubules.

Carcinoma, Renal Cell↗
PubMed1987

Effect of cholestyramine on bile acid metabolism in conventional rats.

Effects of cholestyramine on biliary secretion of cholesterol, phospholipids and bile acids and fecal excretion of sterols and bile acids were examined in Wistar male rats. Six rats were fed a basal diet, and the other six were fed a basal diet supplemented with 5% cholestyramine for eight days. Bile flow and biliary secretion of bile acids and phospholipids (per hour per rat) decreased with cholestyramine treatment, while biliary cholesterol secretion (per hour per rat) remained unchanged. In the biliary bile acid composition, a marked increase of chenodeoxycholic acid with a concomitant decrease of beta-muricholic acid was observed in cholestyramine-treated rats. Fecal excretion of total sterols and bile acids increased about three- and four-fold, respectively, after cholestyramine treatment. The increase of fecal bile acids derived from cholic acid was more predominant than that derived from chenodeoxycholic acid, resulting in an increase of the cholic acid group/chenodeoxycholic acid group ratio.

Animals↗
PubMed1987

The role of atrial pressure in secreting atrial natriuretic polypeptides.

The role of atrial pressure and catecholamines in secreting human atrial natriuretic polypeptides (hANP) were investigated in patients with acute or old myocardial infarction (AMI or OMI). No differences were observed in hANP levels obtained from brachial vein, right atrium, pulmonary artery and femoral artery, suggesting that hANP degradation in the pulmonary circulation has little clinical significance in hANP measurement. Plasma hANP levels in 10 patients with AMI were higher than those in controls and significantly correlated to both mean right atrial pressure (mRA) and pulmonary wedge pressure (PCW) (r = 0.76, p less than 0.05; r = 0.95; p less than 0.01, respectively). In 12 patients with OMI, plasma hANP levels were normal at rest and were significantly increased (p less than 0.01) with bicycle ergometer exercise associated with significant elevations of plasma catecholamine levels, mRA, and PCW. However, the increments of hANP correlated only to those of PCW. These results suggest that the elevation of atrial (principally left atrial) pressure rather than catecholamine stimulates hANP secretion.

Aged↗