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Biomedical subjects

M Hamada

Publications and source records attributed to M Hamada.

At least 523 records · Page 29Linked to original sources
PubMed1986

[The pattern of left ventricular hypertrophy in hypertension and its relation to the hemodynamic and sympathetic responses to exercise].

A wide spectrum of cardiac hypertrophy has been observed in hypertensive patients. In this study, the responses of hemodynamics and sympathetic drives to exercise among hypertensive patients with various types of left ventricular hypertrophy were investigated. Twenty-five patients with untreated essential hypertension (WHO I and II) were classified as those with and without asymmetric hypertrophy (with AH, n = 7; without AH, n = 18) by their echocardiographic patterns. Ten normotensives served as controls. Exercise was performed on a braked bicycle ergometer; the initial work load was 50 watt. The work load increased progressively by 25 watt at three minute-intervals to the target heart rate, exhaustion, or positive ST.T changes. Blood pressure, heart rate, plasma norepinephrine and hemodynamic parameters by echocardiography were estimated at rest and during exercise. Systolic blood pressure and increased heart rate by exercise in all groups. In patients with AH, a rapid increase was observed, and the increase in systolic blood pressure at submaximum exercise was significantly greater than those in normotensives or patients without AH (p less than 0.05). During exercise, endsystolic dimension decreased in normotensives and in patients without AH (p less than 0.01), but the change was not significant in patients with AH. Percent fractional shortening and percent systolic wall thickening of the interventricular septum and left ventricular posterior wall increased significantly in normotensives and in patients without AH (p less than 0.05), but they were unaltered in patients with AH. Although plasma norepinephrine significantly increased in all groups by exercise, the increase in patients with ASH was greater than those in the other groups (p less than 0.05). These results suggest that hyperresponsiveness of systolic blood pressure and heart rate to exercise may play a role in the pathogenesis of AH, and that this type of hypertrophy could be associated with abnormalities of the sympathetic nervous system.

Adult↗
PubMed1986

[Bladder tumor presenting multiple osteoblastic bone metastases].

A 67-year-old man who had undergone partial cystectomy for a bladder tumor (stage pTlb) about two years earlier, was seen with the complaint of lumbago. KUB examination revealed multiple osteoblastic lesions at the lumbar vertebrae and pelvic bone. Furthermore, additional osteoblastic lesions were detected at the thoracic vertebrae, ribs, humeral bones, femoral bones and claviculae. Osteolytic lesions also were recognized at the ribs and claviculae, although osteoblastic change was dominant. Pathologically, transitional cell carcinoma had invaded the bones, and it was suspected that they had metastasized from the bladder tumor.

Aged↗
PubMed1985

Studies on the adenylate kinase isozymes from the serum and erythrocyte of normal and Duchenne dystrophic patients. Isolation, physicochemical properties, and several comparisons with the Duchenne dystrophic aberrant enzyme.

Two species of adenylate kinase isozymes (ATP:AMP phosphotransferase, EC 2.7.4.3) from human Duchenne dystrophic serum were separated by Blue Sepharose CL-6B affinity column chromatography. One of these species was the "aberrant" adenylate kinase isozyme, found specifically in the Duchenne type of this disease (Hamada, M., Okuda, H., Oka, K., Watanabe, T., Ueda, K., Nojima, M., Kuby, S.A., Manship, M., Tyler, F., and Ziter, F. (1981) Biochim. Biophys. Acta 660, 227-237). The separated aberrant form possessed a molecular size of 98,000 (+/- 1,500), whereas the normal serum species of the enzyme was 87,000 (+/- 1,600) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, by gel filtration, and by sedimentation equilibrium. The sedimentation coefficient of each species was found to be 5.8 S for the aberrant form and 5.6 S for the normal form, respectively. The subunit size (Mr = 24,700) of the aberrant enzyme in 8 M urea proved to be very similar to that of the normal human liver enzyme (Hamada, M., Sumida, M., Okuda, H., Watanabe, T., Nojima, M., and Kuby, S.A. (1982) J. Biol. Chem. 257, 13120-13128), and the normal species subunit (Mr = 21,700) was found to be very similar to that of the normal human muscle enzyme (Kuby, S.A., Fleming, G., Frischat, A., Cress, M.C., and Hamada, M. (1983) J. Biol. Chem. 258, 1901-1907). Both species were tetrameric enzymes in the serum. The amino acid composition for the normal species was similar to that for the muscle-type enzyme, and that for the aberrant species was similar to the liver enzyme, but with some notable exceptions in both cases. Thus, the normal species had no tryptophan and two half-cystine residues/subunit; whereas, there was 1 tryptophan and 4 half-cystine residues/subunit of the aberrant molecule. The amino acid composition of both serum isozymes when compared to their respective muscle or liver-type enzyme differed mainly in the content of Glu, Asp, His, Leu, Ile, Gly. Kinetic properties of the two forms of human serum adenylate kinase were studied at limiting concentrations of both ADP3- and MgADP- in the reverse reaction and of AMP2- and MgATP2- in the forward reaction. The type of reaction mechanism compatible with the data was a two-substrate random quasiequilibrium type of mechanism without independent binding of the substrates and with a rate-limiting step largely at the interconversion of the ternary complexes.

Adenylyl Cyclases↗
PubMed1985

Adverse effects of atrial fibrillation and syncope induced by calcium-channel blockers in hypertrophic cardiomyopathy.

Calcium-channel blockers are useful for the treatment of hypertrophic cardiomyopathy (HCM), but, their adverse effects, especially, those of diltiazem, have not been of much concern. Forty patients with HCM were treated with calcium-channel blockers such as nifedipine, diltiazem, and verapamil. Atrial fibrillation was induced by diltiazem in two patients and verapamil induced syncope in one patient. The clinical and hemodynamic characteristics of the patients were as follows. All of them had the obstructive type of HCM (HOCM). One of them had a high pressure gradient of the left ventricular outflow tract and the others had earlier onset. In these patients, the left atrial overload seemed to be severe. The vasodilating action of calcium-channel blockers decreases the systemic pressure and in turn, may increase the pressure gradient and the left ventricular end-diastolic pressure. The elevated left ventricular end-diastolic pressure causes the left atrial overload which could be at risk of atrial fibrillation in patients with HCM. Therefore, calcium-channel blockers should be used carefully in peculiar cases of HOCM.

Adult↗
PubMed1985

Metabolism of lithocholic and chenodeoxycholic acids in the squirrel monkey.

Metabolism of lithocholic acid (LCA) and chenodeoxycholic acid (CDCA) was studied in the squirrel monkey to clarify the mechanism of the lack of toxicity of CDCA in this animal. Radioactive LCA was administered to squirrel monkeys with biliary fistula. Most radioactivity was excreted in the bile in the form of unsulfated lithocholyltaurine. The squirrel monkey thus differs from humans and chimpanzees, which efficiently sulfate LCA, and is similar to the rhesus monkey and baboon in that LCA is poorly sulfated. When labeled CDCA was orally administered to squirrel monkeys, less than 20% of the dosed radioactivity was recovered as LCA and its further metabolites in feces over 3 days, indicating that bacterial metabolism of CDCA into LCA is strikingly less than in other animals and in humans. It therefore appears that LCA, known as a hepatotoxic secondary bile acid, is not accumulated in the squirrel monkey, not because of its rapid turnover through sulfation, but because of the low order of its production.

Animals↗
PubMed1985

Clinical significance of measurements of serum apolipoprotein A-I, A-II and B in hypertriglyceridemic male patients with and without coronary artery disease.

To examine the relationship of hypertriglyceridemia to coronary artery disease (CAD), we measured serum cholesterol, triglyceride, high density lipoprotein cholesterol (HDL-C) and apolipoproteins (apo) A-I, A-II and B in 82 male patients with angiographically defined CAD and 140 age-matched healthy controls. The CAD patients had significantly lower apo A-I and A-II and HDL-C levels, but had higher apo B and triglyceride levels than the controls. After adjustments of apolipoproteins for serum triglyceride, CAD patients had significantly higher apo B and lower apo A-I and A-II levels than the controls. Discriminant analysis showed that apo B was the best discriminator and that apo A-I was next. In the normotriglyceridemic subgroup HDL-C also had a sufficient power for discrimination between CAD patients and the controls, but in the hypertriglyceridemic subgroup HDL-C had no discriminative power. Both apo A-I and B had significant discriminative power between CAD patients and the controls, independently of the serum triglyceride level. These results indicate that measurements of serum apo A-I and apo B are useful for the study of coronary risk factor in hypertriglyceridemic subjects. Finally, it is necessary to sub-classify dyslipoproteinemia by serum apolipoprotein levels for predicting the future occurrence of CAD in the general population.

Adult↗
PubMed1985

Difference in myocardial characteristics between hypertrophic cardiomyopathy and myocardial hypertrophy due to essential hypertension.

To investigate the qualitative difference in myocardial hypertrophy that exists between hypertrophic cardiomyopathy (HCM) and essential hypertension (HT), we measured the mean wall thickness (MWT), the early diastolic time intervals (IIA-MVO time: from the second heart sound to the point of mitral valve opening, MVO-O time: from MVO to the O point of apexcardiogram) and the MVO-O/IIA-MVO ratio. The MWT in HCM and HT was measured by biventriculogram and echocardiogram, respectively. The MWT showed no significant difference between HT (13.1 +/- 3.0 mm) and non-obstructive type of HCM (14.8 +/- 3.7), but the MWT in obstructive type (1.08 +/- 0.24) was significantly thinner than that in HT. As the MWT increased, both IIA-MVO and MVO-O time were prolonged in both groups. But the mode of prolongation was quite different. In HT, the prolongation of the IIA-MVO time was almost always greater than that of the MVO-O time. In HCM, the prolongation of the latter was greater than that of the former. The MVO-O/IIA-MVO ratio in HT was significantly less than that in normal subjects, but those in HCM were significantly greater. These findings suggest that the differences in the early diastolic time intervals between HCM and HT are not due to the magnitude of the left ventricular hypertrophy, but due to myocardial characteristics.

Adult↗
PubMed1985

The analysis of systolic and diastolic time intervals: a more sensitive non-invasive method in the assessment of left ventricular dysfunction in the patients with essential hypertension.

Time indices and volumetric parameters were investigated in patients with essential hypertension subdivided into three groups according to the WHO stage classification. The ratio of ejection time (ET) and pre-ejection period (PEP), ET/PEP remained within normal range in WHO-I but decreased significantly in WHO-II and reached extremely low values in WHO-III. ET did not change in WHO-I and WHO-II but became significantly reduced in WHO-III. Prolongation of PEP in WHO-II and WHO-III increased with progression of hypertensive stage. Isovolumic relaxation time (IRT) showed the same pattern as the prolongation of PEP; positive correlation between PEP and IRT was observed (r=0.55). On the other hand, significant changes of volumetric parameters were only observed in WHO-III. These results indicated that the time indices were a more sensitive parameter than the volumetric ones in the assessment of left ventricular dysfunction in the patients with essential hypertension.

Adult↗
PubMed1985

Saquayamycins, new aquayamycin-group antibiotics.

From the culture broth of Streptomyces nodosus MH190-16F3, four new antibiotics have been isolated, and named saquayamycins A, B, C and D. The compounds are glycosides of aquayamycin, and among aquayamycin-group antibiotics they are most closely related to P-1894B (vineomycin A1). All saquayamycins act on Gram-positive bacteria and inhibit the growth of adriamycin-sensitive and adriamycin-resistant P388 leukemia cells.

Animals↗
PubMed1985

Isolation and characterization of terpentecin, a new antitumor antibiotic.

A new antitumor antibiotic, terpentecin was isolated from the culture broth of strain MF730-N6. Strain MF730-N6, isolated from soil, was found to belong to the genus Kitasatosporia. The antibiotic was extracted with chloroform, purified by column chromatography using silica gel and Diaion HP-20 successively, and finally purified by high performance reverse-phase thin layer chromatography. The molecular formula of terpentecin was determined to be C20H28O6 (molecular weight, 364). The antibiotic inhibited the growth of Gram-positive and Gram-negative bacteria, and prolonged the survival period of mice bearing leukemia L-1210, P388 and Ehrlich ascites carcinoma.

Actinomycetales↗