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Biomedical subjects

T Miyazaki

Publications and source records attributed to T Miyazaki.

At least 793 records · Page 44Linked to original sources
PubMed1987

Effect of 12-O-tetradecanoylphorbol-13-acetate (TPA) on Epstein-Barr virus (EBV)-infected cells.

We have examined if 12-O-tetradecanoylphorbol-13-acetate (TPA) enhances soft agar clonability in Epstein-Barr virus (EBV)-infected cells on the basis of interaction between EBV and TPA. When primary human cord blood lymphocytes (HUCLs) were exposed to two different strains of EBV (B95-8 and NPC-KT) and seeded in soft agar medium containing TPA (0.25 ng/ml), it was observed that the number of transformed colonies increased. However, TPA did not enhance the number of colonies in two EBV genome-positive epithelial hybrid cell lines (NPC-KT and D98/HR-1).

Cell Line↗
PubMed1987

Establishment of an Epstein-Barr virus (EBV) genome-positive subline of Ramos (Ramos/NPC) following infection of Ramos with nasopharyngeal carcinoma (NPC)-derived EBV.

An Epstein-Barr virus (EBV) genome-positive epithelial hybrid cell line, NPC-KT, derived from the fusion of primary nasopharyngeal carcinoma cells with a human epithelial cell line of adenoid origin has previously been described (Takimoto, Kamide, and Umeda, 1984a; Takimoto, Ogura, Sato, and Hatano, 1984b; Takimoto, Ogura, Sato, Umeda, and Hatano, 1985). The NPC-KT cells produce virus (NPC virus) with both transforming and lytic properties. An EBV genome-negative human lymphoblastoid cell line, Ramos, was infected with NPC virus. Three months after infection, more than 90% of the cell population expressed EBV-associated nuclear antigen (EBNA). Approximately 40% of the cells exhibited a brilliant pattern, whereas the remaining 50% of the cells showed a faint granular pattern. The result suggests that there may be heterogeneity in NPC virus.

Antigens, Viral↗
PubMed1987

Development and regression of intimal thickening of arterially transplanted autologous vein grafts in dogs.

To investigate the influence of hemodynamic conditions on intimal thickening of arterially transplanted autologous vein grafts, two experimental models of canine femoral arteries were prepared. In group I, in which an autologous vein graft was transplanted under abnormal flow conditions (distal poor runoff), intimal thickening gradually developed and reached 358 +/- 33 microns at 8 months, whereas no thickening was observed under normal flow conditions at any time throughout the observation period. In group II the thickened intima, which developed under abnormal flow conditions for 1 month, was reimplanted into the contralateral leg under normal flow conditions. The thickness of the intima markedly regressed to about 66% at 1 month, 50% at 3 months, and 25% at 8 months, respectively, whereas no regression of the thickened intima was observed under continued abnormal flow conditions. Electron microscopic studies revealed that the thickened intima in group I was composed of proliferation of transformed smooth muscle cells with a marked increase in the mitochondria, the rough endoplasmic reticulum, and an abundant fibrous matrix, whereas with the regressed thickness of the intima of group II, the smooth muscle cells were spindle-shaped with distinct myofibrillae. These results provide pertinent data on the process involved in the intimal thickening in cases of graft placement.

Animals↗
PubMed1987

Local myocardial electrogram and potassium concentration changes in superficial and deep intramyocardium and their relations with early ischaemic ventricular arrhythmias.

Bipolar myocardial electrograms and extracellular potassium concentrations were simultaneously monitored using double barrelled probes during 30 min of acute ischaemia in 15 dogs in vivo. The responsiveness of the time from the onset of the limb lead electrocardiogram to the peak deflection of the local electrogram to extracellular potassium changes was more prominent in superficial intramyocardium than in deep intramyocardium, despite similar changes in potassium concentration in both layers. The changes in electrogram duration and amplitude were related to extracellular potassium concentration both in superficial and deep intramyocardium. Immediate phase ventricular arrhythmias (within the first 10 min of acute ischaemia) were characterised by delayed activity mainly due to an increase in the time to peak of the electrogram in superficial intramyocardium. In contrast, in dogs showing delayed phase arrhythmias (within 10-30 min of acute ischaemia) delayed activity associated with pronounced changes in potassium concentration and electrogram duration and amplitude were noted in deep intramyocardium. Thus the two phasic appearances of early ischaemic ventricular arrhythmias with different origins seem to be related to the features of the conduction pathway in superficial intramyocardium and the severe local electrogram changes associated with a pronounced increase in extracellular potassium concentration in deep intramyocardium.

Acute Disease↗
PubMed1987

Ultrastructural studies of the skin and cultured fibroblasts in I-cell disease.

The skin and cultured fibroblasts from a patient with I-cell disease were examined by electron microscopy. Multiple vacuolations were seen in fibroblast and/or histiocyte-like cells, secretory cells of eccrine glands, and Schwann cells of the skin. Vacuolar inclusions were single membrane-limited, and contained a few reticulo-floccular and vesicular materials, endothelial cells of the dermal capillaries contained other types of inclusions, which were also membrane-limited, more electron dense, and multivesicular. The epidermis and pilosebaceous appendages seemed to be normal. Cultured skin fibroblasts contained prominent inclusions which varied in size and morphology. Acid phosphatase activity was seen in some of those inclusions, indicating their derivation from lysosomes. These findings suggest that the I-cell disease is a type of lysosomal storage disease and that electron microscopic examination of normal-appearing skin in this disease may contribute to the diagnosis.

Cells, Cultured↗
PubMed1987

Effects of rokitamycin and other macrolide antibiotics on Mycoplasma pneumoniae in L cells.

Fifty strains of Mycoplasma pneumoniae in L cells were tested for susceptibility to macrolide antibiotics. Rokitamycin, a new macrolide antibiotic, was most active against these organisms, with an MIC for 90% of strains of 0.007 microgram/ml. The MICs of erythromycin, josamycin, and kitasamycin for 90% of strains were 0.03, 0.03, and greater than or equal to 0.06 microgram/ml, respectively. Based on these results, rokitamycin is a promising antibiotic for the treatment of mycoplasmal infections, and further clinical investigations are needed.

Anti-Bacterial Agents↗
PubMed1987

Nucleotide sequence of the 2,3-dihydroxybiphenyl dioxygenase gene of Pseudomonas pseudoalcaligenes.

2,3-Dihydroxybiphenyl dioxygenase, which catalyzes ring metacleavage of 2,3-dihydroxybiphenyl, is encoded by the bphC gene of Pseudomonas pseudoalcaligenes KF707 (K. Furukawa and T. Miyazaki, J. Bacteriol. 166:392-398, 1986). We determined the nucleotide sequence of a DNA fragment of 2,040 base pairs which included the bphC gene. The fragment included one open reading frame of 912 base pairs to accommodate the enzyme. The predicted processed amino acid sequence of the enzyme subunit consisted of 302 residues, and its 12 NH2-terminal residues were in perfect agreement with those determined for the enzyme. Approximately 10 base pairs upstream from the initiation codon for 2,3-dihydroxybiphenyl dioxygenase, there was a base sequence complementary to the 3' end of the 16S rRNA from Pseudomonas aeruginosa. There was no promoterlike sequence in the region upstream of the bphC gene, but another long open reading frame was present. A putative bphD gene encoding a metacleavage compound-hydrolyzing enzyme was suggested in the region downstream of the bphC gene.

Amino Acid Sequence↗
PubMed1987

Transfection of human nasopharyngeal epithelial cells with Epstein-Barr virus DNA.

Transfection experiments using Epstein-Barr virus (EBV) DNA were carried out to examine whether three different epithelial cell lines (Ad-AH, D98, and KB) could be transfected and whether biologically active virus could be recovered. We found that the Ad-AH cells derived from the human nasopharynx were more transfectable, as determined by the synthesis of EBV-specific antigens. Concentrates of supernatant fluids obtained from transfected Ad-AH cells were capable of transforming human cord blood lymphocytes (HCBLs). However, no concentrates of supernatant fluids obtained from transfected epithelial cell lines outside the nasopharynx (D98 and KB) were capable of transforming HCBLs.

Cell Line↗
PubMed1987

Analysis of urinary aldosterone metabolites in the guinea-pig.

Analysis of urinary metabolites of [1, 2-3H]-aldosterone was performed in the male guinea-pig. Separation of urinary metabolites was carried out by countercurrent distribution followed by DEAE-Sephadex A-25 column chromatography. A major component was obtained which was both hydrolyzable with sulphatase from Helix pomatia and solvolyzable. Paper chromatography of freed steroids revealed the presence of at least two components and the major aglycone cochromatographed with 3 beta, 5 alpha-tetrahydroaldosterone. In order to get more information about the structure of urinary metabolites, a total of 68 mg of aldosterone was injected into three male guinea-pigs and separation of urinary metabolites was performed in a similar manner. A major component obtained showed the color reaction positive for sulphate (modified rhodizonic acid test) and negative for glucosiduronate (naphthoresorcinol test). Gas chromatographic-mass spectrometric analysis of aglycones released from this conjugate revealed the presence of 3 beta, 5 alpha-tetrahydroaldosterone and an another aglycone, tentatively identified as 21-deoxy-tetrahydroaldosterone. Taken together, it was concluded that 3 beta, 5 alpha-tetrahydroaldosterone-monosulphate and 21-deoxy-tetrahydroaldosterone-monosulphate comprised most of urinary conjugated metabolites of aldosterone in the male guinea-pig.

Aldosterone↗
PubMed1987

Examination of the direct effects of antianginal agents on the hypoxic canine myocardium.

The myocardial protective effect of nicorandil, N-(2-hydroxyethyl) nicotinamide nitrate ester, against hypoxia was examined in comparison with that of nitroglycerin in 22 open chest dogs. The regional ventricular myocardium was perfused for 5 min with a hypoxic solution in 8 dogs (Group 1), with a hypoxic solution containing 0.5 or 2.5 mg/dl of nicorandil in 7 dogs (Group 2) and with a hypoxic solution containing 0.5 mg/dl of nitroglycerin in 7 dogs (Group 3). In Group 2, the ATP content of the hypoxic myocardium was 3.14 +/- 0.37 mumol/g, which was less than that in the uninvolved myocardium (4.31 +/- 0.57 mumol/g) but significantly higher than those of the hypoxic myocardium in Groups 1 and 3 (2.09 +/- 0.45 and 2.39 +/- 0.33 mumol/g, respectively). The lactate content of the hypoxic myocardium in Group 2 (5.05 +/- 1.13 mumol/g) was less than those of the hypoxic myocardium in Groups 1 and 3 (8.77 +/- 2.34 and 8.98 +/- 2.08 mumol/g, respectively). This protective effect was not caused by the hemodynamic changes. In contrast, nitroglycerin did not show any protective effects on the hypoxic myocardium.

Adenosine Diphosphate↗
PubMed1987

Beneficial effects of intracoronary nicardipine on hypoxic myocardium.

Regional effects of intracoronary administration of nicardipine, a dihydropyridine derivative with calcium blocking activity, were studied in 13 open-chest dogs. Hypoxic, constant-flow perfusion was done in the area supplied by the distal left anterior descending artery. The 5-min regional hypoxic perfusion did not result in significant alterations in either heart rate or aortic pressure in 6 control dogs perfused with original Krebs-Henseleit solution (KHS), which was deoxygenized by mixed gas (95%N2 and 5%CO2), and in 7 dogs perfused with nicardipine-containing (0.2 mg/dl) KHS. A transmural biopsy after 5 min of perfusion revealed a less severe metabolic deterioration in nicardipine-treated dogs than in control dogs, as indicated by a higher ATP content (2.84 +/- 0.43 vs. 2.23 +/- 0.45 mumol/g, wet weight). The sequence of regional contractile deterioration was not different between the 2 groups. In conclusion, regional nicardipine administration showed a myocardial protective effect which was not mediated by afterload reduction in the whole heart.

Adenine Nucleotides↗
PubMed1987

Non-T, non-B acute lymphocytic leukemias: cellular origin based on molecular analyses of immunoglobulin and T-cell alpha- and beta-chain receptor gene rearrangements.

Fifteen non-T, non-B acute lymphocytic leukemia (ALL) cases were investigated for determining cellular origin based on molecular (immunoglobulin and T-cell alpha-receptor (TcR alpha) and T-cell beta-receptor (TcR beta) genes) and immunophenotypical analyses. As defined by monoclonal antibodies, they were classified into 2 groups; 12 cases as common ALL antigen (CALLA)-positive ALL and 3 cases as CALLA-negative ALL. Southern blot analysis revealed that 11 CALLA-positive ALL cases contained rearranged JH gene and 2 of them contained rearranged Jx genes, similar to recent views that most CALLA-positive leukemic cells are neoplastic B-cell precursors. One CALLA-positive ALL case, whose leukemic cells were also Leu-1 positive, showed no rearrangement of JH and TcR beta genes. On the other hand, non-T, non-B CALLA-negative ALL, so called null ALL, consisted of heterogenous groups with regard to lymphocyte differentiation and lineage; one out of 3 null ALL cases may be truely undifferentiated as shown neither JH nor TcR beta gene rearrangement, but other 2 cases showed either JH or TcR beta gene rearrangement. Dual rearrangements of Ig and TcR beta genes occur frequently in 3 out of 15 non-T, non-B ALL cases, but all cases of bigenotype showed no doubly marked profile and retained a completely fidelous immunophenotypic pattern. We further investigated the possibility that analysis of TcR alpha gene may be useful for determining cellular origin of non-T, non-B ALL leukemic cells.

Genotype↗