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Biomedical subjects

M Hamada

Publications and source records attributed to M Hamada.

At least 487 records · Page 27Linked to original sources
PubMed1988

Significance of systolic time intervals in predicting prognosis of primary pulmonary hypertension.

To elucidate the characteristics of left ventricular (LV) function and LV shape in primary pulmonary hypertension (PPH), systolic time intervals (STIs) and two-dimensional echocardiograms in seven patients with PPH were studied and compared with those of 12 normal controls. Serial changes in STIs were also analyzed as to clinical outcomes. All patients were females and aged from 14 to 53 years. The follow-up period was 50 +/- 30 months, and five patients died of cardiac causes during the study period. The patients with PPH had a significantly prolonged pre-ejection period (PEP) and PEP index. Left ventricular ejection time (LVET) and the LVET index in the PPH group, at the time of diagnosis, showed no statistical differences compared with those of the controls, but three patients with PPH showed a marked shortening of LVET. A significant decrease in the LVET/PEP ratio was observed in patients with PPH. Left ventricular end-diastolic dimension (EDD) and end-systolic dimension (ESD) were significantly less in patients with PPH than in the controls. No difference in percent fractional shortening of the left ventricle and the mean velocity of circumferential fiber shortening was observed. The degree of LVET shortening correlated with the decrease in EDD (r = 0.97). During follow-up, marked shortening of the LVET index, below approximately 350 msec, was observed immediately before death or clinical deterioration. From these results, we conclude that in PPH, (1) left ventricular function is impaired due to reduced volume of the left ventricle during diastole, reflecting a shortening of LVET and the LVET index, and (2) analysis of serial LVET indexes is useful for predicting the prognosis.

Adolescent↗
PubMed1987

Association of the atrial natriuretic factor receptor with guanylate cyclase in solubilized rat glomerular membranes.

The elution profile of solubilized rat glomerular membranes from a gel filtration column showed two peaks of 125I-ANF (atrial natriuretic factor) binding (367 +/- 21, 156 +/- 12 KDa). Over 85% of the total binding for the extract was in the 367 KDa peak. Guanylate cyclase activity was correlated with 125I-ANF specific binding. ANF activation of guanylate cyclase was also observed. As observed previously with particulate membrane, Scatchard-analysis of ANF binding data with the solubilized extract was consistent with a two-site model. Both affinities (Kd's), 4 pM and 1 nM, are within the range of blood concentrations reported for ANF. These observations suggest that most rat glomerular ANF receptors are large molecular complexes coupled with guanylate cyclase in the 300-350 KDa size range.

Animals↗
PubMed1987

Atrial natriuretic peptide binding properties of purified rat glomerular membranes.

125I-ANP (3-[125I] iodotyrosyl28) binding studies with purified rat glomerular membranes indicate two types of physiologically relevant hormonal receptors, Types I and II, Kd approximately 5 pM and approximately 2.5 nM, respectively. All preparations were essentially free of capsular and tubular contamination. Binding data indicated that Type I receptors were three times more concentrated than Type II receptors in purified membrane fractions. When purified membranes were cross-linked with 125I-rANP, using disuccinimidyl suberate and separated by SDS-PAGE, approximately 75- and approximately 140-kDa proteins were specifically labeled in a ratio of approximately 3:1, respectively. Thus, in purified renal glomerular membranes, Type I receptors with molecular weight of approximately 75-kDa appeared to predominate and would be detectably saturated at circulating ANP concentrations as low as 15 pg/ml. These findings could account for the exquisite sensitivity of natriuretic response to ANP.

Animals↗
PubMed1987

Comparative effects of calcium-channel blockers and beta-adrenergic blocker on early diastolic time intervals and A-wave ratio in patients with hypertrophic cardiomyopathy.

To compare the effects of calcium-channel blockers with those of beta-adrenergic blockers in patients with hypertrophic cardiomyopathy (HCM), diastolic time intervals (IIA-O time, from the second heart sound to the O point of apexcardiogram, IIA-MVO time, from IIA to the mitral valve opening, and MVO-O time, from the MVO to the O point of apexcardiogram), and A-wave ratio measured from apexcardiogram were evaluated before and after more than three months of treatment. In both groups, heart rate significantly decreased after treatment. The IIA-MVO time was not affected by either drug. The IIA-O and the MVO-O times were significantly shortened by calcium-channel blockers (from 234.6 +/- 77.4 ms to 204.6 +/- 39.2 ms; p less than 0.01, and from 133.1 +/- 66.4 ms to 100.3 +/- 34.0 ms; p less than 0.01, respectively). However, they were not affected by beta-adrenergic blocker. A-wave ratio significantly decreased after calcium-channel blockers (from 18.0 +/- 9.8% to 13.7 +/- 7.3%; p less than 0.01) and beta-adrenergic blocker (from 21.7 +/- 12.6% to 17.2 +/- 8.0%; p less than 0.01). From these observations, it is suggested tht calcium-channel blockers improved the early diastolic filling rate, whereas beta-adrenergic blocker did not affect it. It is concluded that the effects of calcium-channel blockers and beta-adrengergic blocker on early diastolic time intervals were different in patients with HCM.

Adrenergic beta-Antagonists↗
PubMed1987

Clinical significance of early diastolic time intervals for the differentiation of idiopathic dilative cardiomyopathy from ischemic cardiomyopathy.

In order to differentiate idiopathic dilative cardiomyopathy from ischemic cardiomyopathy noninvasively, systolic time intervals (STIs) and early diastolic time intervals were investigated in patients with idiopathic dilative cardiomyopathy (n = 11), patients with ischemic cardiomyopathy (n = 8), and normal controls (n = 17). Minimal left ventricular pressure and pulmonary capillary wedge pressure (PCWP) were also measured to clarify the relationship between early diastolic time intervals and early diastolic hemodynamics. Cardiac function estimated by STIs was markedly depressed both in idiopathic dilative cardiomyopathy and ischemic cardiomyopathy, and there was no difference between the two diseases. In early diastolic time intervals, IIA-O time (the interval from the aortic component of the second heart sound to the O point of apexcardiogram) was significantly prolonged both in idiopathic dilative cardiomyopathy (144 +/- 31 (SD); p less than 0.01) and ischemic cardiomyopathy (153 +/- 15; p less than 0.01) compared to normal controls (126 +/- 11). IIA-MVO time (the interval from IIA to the mitral valve opening) in idiopathic dilative cardiomyopathy (49 +/- 23) was significantly shorter than that in normal controls (70 +/- 8; p less than 0.05). On the contrary, IIA-MVO time in ischemic cardiomyopathy (126 +/- 11) was markedly prolonged compared with normal controls (p less than 0.01) and idiopathic dilative cardiomyopathy (p less than 0.01). MVO-O time was significantly prolonged in idiopathic dilative cardiomyopathy (94 +/- 18; p less than 0.01). However, it was conversely shortened in ischemic cardiomyopathy (25 +/- 15) compared with normal controls (54 +/- 7; p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Enhanced blood pressure response to isometric handgrip exercise in patients with essential hypertension: effects of propranolol and prazosin.

To elucidate whether a difference exists in blood pressure (BP) elevation during isometric handgrip exercise (IHG) between essential hypertensives (EHT) and normotensives (NT), IHG was carried out in 12 NT and 46 EHT under constant sodium intake using a new instrument. The acute effects of propranolol and prazosin on IHG were also examined in EHT. The change in systolic BP (delta SBP) during IHG in EHT, delta SBP = 61 +/- 21 mmHg, was markedly greater than that in NT, delta SBP = 28 +/- 4 mmHg. Among EHT, delta BP increased with increasing severity of hypertension. Neither the changes in plasma norepinephrine nor in epinephrine during IHG showed significant differences between EHT and NT. The pressor response during IHG could not be suppressed by propranolol, but about 30% suppression of BP was observed during IHG with prazosin. It is concluded from these findings that EHT have an exaggerated BP response to IHG that is due to increased post-junctional alpha 1-adrenoceptors.

Adult↗
PubMed1987

Intracellular free calcium concentration, Ca++ channel and calmodulin level in experimental hypertension in rats.

Using fluorescent calcium indicator quin2, we studied intracellular free calcium concentration in platelets that have a number of features similar to vascular smooth muscle cells. Intracellular free calcium concentration in platelets of male SHR was significantly higher at 4, 11 and 28 weeks old compared with age-matched male WKY. However, no significant difference was observed in platelets cytosolic free calcium level of DOCA-salt hypertensive and two-kidney, one clip hypertensive rats in the chronic stage. Cardiac Ca++ channels were estimated by means of radioligand binding method with [3H]-nimodipine. No significant changes were observed in the concentration and affinity of cardiac Ca++ channel in SHR, DOCA-salt hypertensive and two-kidney, one clip hypertensive rats. Calmodulin levels in mesenteric arteries of SHR were significantly decreased in comparison with those of WKY. However no significant differences were observed in DOCA-salt hypertensive rats in the chronic stage. These results indicate that the increase in intracellular free calcium concentration of SHR is not the secondary change caused by high blood pressure. It is impossible to detect the ratio of the three states (open, resting and inactivated) of Ca++ channel. Therefore, there remains a possibility of the changes in the ratio of the states of Ca++ channel. The observed abnormalities of Ca++ regulation may contribute to the pathogenesis of hypertension.

Animals↗
PubMed1987

Monocyclic beta-lactam antibiotics: synthesis and antibacterial activity of 4-(substituted ethyl)-2-azetidinone-1-sulfonic acid derivatives.

The synthesis and antibacterial activity of sodium (3S,4R)-3-[2-(2-aminothiazol-4-yl)-(Z)-2-(O-substituted oxyimino)acetamido]-2-azetidinone-1-sulfonates having various substituted ethyl groups at the C-4 position are described. Among various substituents explored, the (substituted isothiuronio)ethyl groups were found to have strong antibacterial activity against a variety of Gram-negative bacteria, and moreover, the ethylene isothiuronium derivative exhibited moderate antibacterial activity against Staphylococcus aureus.

Anti-Bacterial Agents↗
PubMed1987

[ECG-gated magnetic resonance imaging of the left ventricle: visualization of anatomical characteristics and quantification of wall thickness and ventricular volume in left ventricular hypertrophy].

Electrocardiography- and respiration-gated magnetic resonance imaging (MRI) was performed using a 0.15-Tesla resistive magnet system in 54 patients with left ventricular hypertrophy to define the site and extent of abnormal wall thickness and to estimate left ventricular function. Because the major cardiac axes are not orthogonal to the conventional transverse, sagittal or coronal planes, the long-axis and short-axis images of the left ventricle were obtained at the end-diastolic and end-systolic phases. The anatomic characteristics of concentric hypertrophy, asymmetric septal hypertrophy, and asymmetric apical hypertrophy were clearly demonstrated by MRI, even in patients with poor echocardiographic images. Quantitatively, left ventricular wall thicknesses obtained from MR images correlated well with those obtained from echocardiography (r = 0.95), and regression was y = 0.99x + 0.39, and so did the ratios of wall thickness of the interventricular septum to the left ventricular posterior wall (r = 0.91, y = 0.80x + 0.24). Left ventricular volumes calculated by the area-length method from MRI and those from left ventriculography also correlated well (r = 0.98, y = 1.13x + 24.5). In conclusion, using the gated long-axis and short-axis MR images of the left ventricle, the anatomical location and extent of hypertrophy and left ventricular volumes are noninvasively demonstrated.

Aged↗
PubMed1987

Structure and function of adenylate kinase isozymes in normal humans and muscular dystrophy patients.

Two isozymes of adenylate kinase from human Duchenne muscular dystrophy serum, one of which was an aberrant form specific to DMD patients, were separated by Blue Sepharose CL-6B affinity chromatography. The separated aberrant form possessed a molecular weight of 98,000 +/- 1,500, whereas the normal serum isozyme had a weight of 87,000 +/- 1,600, as determined by SDS-polyacrylamide gel electrophoresis, gel filtration, and sedimentation equilibrium. The sedimentation coefficients were 5.8 S and 5.6 S for the aberrant form and the normal form, respectively. Both serum isozymes are tetramers. The subunit size of the aberrant isozyme (Mr = 24,700) was very similar to that of the normal human liver isozyme, and the subunit size of the normal isozyme (Mr = 21,700) was very similar to that of the normal human muscle enzyme. The amino acid composition of the normal serum isozyme was similar to that of the muscle-type enzyme, and that of the aberrant isozyme was similar to that of the liver enzyme, with some exceptions in both cases.

Adenylate Kinase↗
PubMed1987

[Study on relationships between sonographic endometrial images and ovarian hormone levels].

Sixty-seven and 109 sonographic endometrial images obtained from 67 infertile patients and 5 healthy volunteers with normal ovulatory cycles, respectively, were investigated with regard to serum estradiol (E2) and progesterone (P) levels. The ultrasound devices used were sector electronic scanners (3.5 MHz). 1) Endometrial images were able to be classified into four pattern types, according to the criteria reported by Sakamoto (1985), using a gray-scale contact compound scan. Pattern 1: linear cavity echo, pattern 2: thick hypoechoic endometrium surrounded by thin border echo, pattern 3: thickened border echo, pattern 4: entire echogenic endometrium. 2) Both E2 and P levels were low in pattern 1. The E2 level was significantly higher in pattern 2 than in pattern 1 (p less than 0.01), indicating pattern 2 reflects E2 surges prior to ovulation. The P level was high in pattern 3; and in pattern 4, it was significantly higher than in patterns 1 and 2 (p less than 0.01), indicating that patterns 3 and 4 are in the early and mid-luteal phase, respectively. 3) Sonograms obtained from 12 cases with suspicious luteal phase defects showed an abnormal pattern in the mid-luteal phase. These results indicate that the sonographic endometrial images reflect respective ovarian hormone levels.

Adult↗