Search PubMed⌕ Search

Biomedical subjects

M Hamada

Publications and source records attributed to M Hamada.

At least 469 records · Page 26Linked to original sources
PubMed1988

Cerebral and myocardial infarction induced by nonbacterial thrombotic endocarditis in a patient with ovarian cancer: report of a case.

A 40-year-old woman was admitted to our hospital because of left hemiplegia. She was affected with myocardial infarction and cerebral infarction. Echocardiogram revealed that the aortic and mitral valves had thick and uneven echoes suggesting vegetations. Judging from the finding that repeated blood cultures were negative, we had considered in her lifetime that myocardial and cerebral infarctions were due to embolization associated with nonbacterial thrombotic endocarditis (NBTE). At autopsy, histological diagnosis was made as ovarian cancer with disseminated intravascular coagulation. From the clinical course and the histological findings, we diagnosed this patient as NBTE.

Adult↗
PubMed1988

Benadrostin, new inhibitor of poly(ADP-ribose) synthetase, produced by actinomycetes. I. Taxonomy, production, isolation, physico-chemical properties and biological activities.

Benadrostin, a new inhibitor of poly(ADP-ribose) synthetase was discovered in the fermentation broth of Streptomyces flavovirens MH499-O'F1. It was purified by chromatography followed by solvent extraction and then isolated as colorless prisms. Benadrostin has the molecular formula of C8H5NO4. It was competitive with the substrate, and the inhibition constant (Ki) was 34 microM.

Fermentation↗
PubMed1988

Cloning of macromomycin apoprotein gene from Streptomyces macromomyceticus by use of 50-mer deoxynucleotide probes.

A mixed probe consisting of two synthetic deoxynucleotides (52 and 54 mers referred to as 50-mer) with arbitrarily chosen C or G for the third letters was prepared based on the amino acid sequences No. 31-48 and No. 72-90 of macromomycin (MCM) apoprotein and successfully used to clone the MCM apoprotein gene. Digestion with Sph I of total DNA of MCM-producing Streptomyces macromomyceticus M480-M1 yielded a 2.6-kb fragment that hybridized strongly to the probes. The hybridized probe was stable to washing with 3 x SSC at 75 degrees C. Radioactivity derived from the hybridized probe was comparable to that expected theoretically from hybridization between the probe and the true target sequence. The 2.6-kb fragment was cloned into Escherichia coli RR1 with pBR322 and subsequently subcloned into Streptomyces lividans TK21 with pIJ702. Nucleotide sequence analysis of the cloned fragment verified the existence of the sequence corresponding to the amino acid sequence of MCM apoprotein and about 90% homologies with the probes. Thus, the use of relatively long deoxynucleotide probes with arbitrarily chosen C or G for the third letters will be advantageous in cloning Streptomyces protein genes where more than 90% of the third letters have been known to be C or G. In addition, theoretical diagnosis of hybridization should be a great help to distinguish true positives from false ones.

Amino Acid Sequence↗
PubMed1988

Novel antifungal antibiotics octacosamicins A and B. I. Taxonomy, fermentation and isolation, physico-chemical properties and biological activities.

Two antifungal antibiotics octacosamicins A and B were isolated from the culture broth of a strain of actinomycetes, which was identified as a strain of Amycolatopsis. These antibiotics were isolated by resin adsorption and purified by column chromatography and preparative HPLC. Both antibiotics were found to be new substances from their physico-chemical properties. They showed broad antifungal spectra.

Actinomycetales↗
PubMed1988

Thrazarine, a new antitumor antibiotic. I. Taxonomy, fermentation, isolation and biological properties.

Thrazarine, O-[(3R)-2-diazo-3-hydroxybutyryl)]-L-serine, is a new antitumor antibiotic produced by Streptomyces coerulescens MH802-fF5. Thrazarine was isolated from culture filtrate by Sephadex LH-20 column chromatography and reversed phase HPLC. Thrazarine induced cytolysis of tumor cell lines co-cultured with nonactivated macrophages. This effect was tumor specific because the nontumorigenic cells were not lysed by macrophages in the presence of thrazarine. Thrazarine inhibited DNA synthesis and growth of tumor cells directly. It showed neither antimicrobial activity nor the inhibition of transamidation reactions in contrast to azaserine. Toxicities of thrazarine were much weaker than those of azaserine.

Animals↗
PubMed1988

Synthesis and structure-activity studies of new 4''-O-acyltylosin derivatives of therapeutic interest.

Eleven 4''-O-acyltylosin derivatives were synthesized and subjected to a two-step screening system consisting of antimicrobial activity and esterase stability assays. The new derivatives were all active against macrolide-resistant Staphylococci and mycoplasmas, but only 4''-O-(4-methoxy)phenylacetyltylosin and 4''-O-(4-acetyl)phenylacetyltylosin showed better resistance to mouse liver esterase than 4''-O-phenylacetyltylosin (reference compound C).

Animals↗
PubMed1988

Mode of action of deoxypheganomycin D on Mycobacterium smegmatis ATCC 607.

Deoxypheganomycin D, a specific inhibitor of mycobacteria, inhibits the growth in vitro of Mycobacterium smegmatis ATCC 607 (M. 607) bacteriostatically at concentrations as high as 7 X 10(-5) M. It shows no cross-resistance to paromomycin, capreomycin, viomycin, streptothricin, kanamycin and streptomycin. Deoxypheganomycin D at 2.8 X 10(-7) M where the cell growth of M. 607 is only partially inhibited does not significantly inhibit DNA, RNA or protein synthesis but leads to marked decrease (13% of control) in [14C]glycerol-derived radioactivity in cell-walls. In the presence of 7 X 10(-6) M deoxypheganomycin D, the influx of leucine but not thymidine is affected while the reverse is true with efflux. The data suggest that the effect of deoxypheganomycin D on M. 607 may be related to both the cell membrane and specific mycobacterial lipid like components of the cell-wall.

Amino Acids↗
PubMed1988

[Graft patency and myocardial viability after aorto-coronary bypass surgery evaluated by exercise 201T1 myocardial SPECT].

To evaluate graft patency and myocardial viability after aorto-coronary (AC) bypass surgery, 58 patients (29 with old myocardial infarction and 29 with effort angina) underwent symptom-limited exercise 201T1 myocardial SPECT using a bicycle ergometer before and after surgery. The results were as follows: 1. The overall angiographic graft patency was 87% (97 of 112 grafts). 2. According to the stress SPECT images, graft patencies were 98% for areas with postoperative improvement by 201T1 uptakes, 79% for areas with unchanged patterns, and 53% for areas with worsened patterns. In spite of patent grafts, among cases with worsened 201T1 uptakes the etiologies included perioperative infarction, anastomotic strictures, and poor run-off distal to the anastomoses. 3. Following patency of grafts, postoperative normalized perfusion patterns were observed in 69% (27 of 39 segments) of segments with persistent preoperative low uptakes and 25% (4 of 16 segments) of segments with persistent preoperative defects. Thus, exercise 201T1 myocardial SPECT proved a useful diagnostic means of assessing graft patency and effectiveness. However, after AC bypass surgery, 25% of the regions which had persistent defects before surgery exhibited normal perfusion patterns. These findings suggest that persistent defects may represent hypoperfusion of viable myocardium, and that we should carefully diagnose myocardial scars.

Adult↗
PubMed1988

[Left ventricular volume curve analysis using gated blood pool emission computed tomography].

Analysis of the left ventricular volume curve was performed using gated blood pool emission computed tomography (SPECT) in six patients with old myocardial infarction (MI), five with hypertrophic cardiomyopathy (HCM), three with dilated cardiomyopathy (DCM), and five normal controls (N). Image collection was synchronized with the QRS complex, and each cardiac cycle was divided into nine to 10 frames. In each frame, left ventricular volume was determined based on the number of voxels above the threshold level (50% cut-off level), and the volume curve was fitted to the third harmonics of Fourier analysis. From the fitted curve, the peak ejection rate (PER), the peak filling rate (PFR), end-diastolic volume (EDV), end-systolic volume (ESV) and ejection fraction (EF) were calculated. 1. There were good correlations between SPECT and the conventional gated blood pool (MUGA) for PER (r = 0.694, p less than 0.005), PFR (r = 0.527, p less than 0.025) and EF (r = 0.682, p less than 0.005). 2. PER in MI (2.21 +/- 0.55, mean +/- SD) was lower than in N (3.68 +/- 0.80, p less than 0.05) and HCM (4.85 +/- 2.39, p less than 0.05), and EF in MI (36.6 +/- 6.4) was lower than in HCM (68.7 +/- 23.7, p less than 0.05). 3. There were good correlations between EDVs (y = 1.11x + 5.71, r = 0.877, p less than 0.01), and ESVs (y = 1.05x - 3.88, r = 0.876, p less than 0.01) estimated by MUGA and SPECT.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗