Search PubMed⌕ Search

Biomedical subjects

H Miyoshi

Publications and source records attributed to H Miyoshi.

At least 217 records · Page 12Linked to original sources
PubMed1993

Junctions of the AML1/MTG8(ETO) fusion are constant in t(8;21) acute myeloid leukemia detected by reverse transcription polymerase chain reaction.

The chromosomal translocation, t(8;21), is found frequently in acute myeloid leukemia (AML) with maturation (FAB-M2). We have previously mapped the translocation breakpoints of t(8;21) in a specific intron of the AML1 gene on chromosome 21. In this study, we cloned cDNAs synthesized from a cell line carrying t(8;21) by reverse transcription polymerase chain reaction (RT-PCR) using an AML1-specific primer. The analysis of the cDNAs structure has led to the identification of the fusion of AML1 with a gene named MTG8 on chromosome 8, which seems to be identical to ETO. Northern analysis using MTG8 (ETO) probes detected 7.8-kb and 6.2-kb RNAs and several minor RNAs in the cell line with t(8;21), but failed to detect any transcripts in a cell line without t(8;21). A set of primers were designed to detect the AML1/MTG8(ETO) fusion by PCR. The PCR amplified identical products in all 6 patients and one cell line with t(8;21), suggesting that the AML1/MTG8(ETO) fusion is a constant feature associated with t(8;21) and the junctions of the AML1/MTG8(ETO) fusion are restricted in a unique site. Because the PCR detection of the AML1/MTG8(ETO) fusion at the RNA level is highly sensitive, it can be used as a sensitive method for diagnosis and detection of minimal residual disease in t(8;21) leukemia.

Amino Acid Sequence↗
PubMed1993

Quantitative analysis of electron transport inhibition of rat-liver mitochondrial cytochrome bc1 complex by nitrophenols.

A series of nitrophenolic electron transport inhibitors (2-sec-butyl-4-nitro-6-substituted phenols and 2-sec-butyl-4-substituted-6-nitrophenols) of rat-liver mitochondrial cytochrome bc1 complex (cyt. bc1 complex) was synthesized. To obtain information on the three-dimensional structure of the ubiquinone redox site of cyt. bc1 complex, the structure-inhibitory activity relationship was examined by regression analysis using physiocochemical substituent parameters. The inhibitory activity increased as the hydrophobicity and the electron-withdrawing ability of the 4- and 6-substituents increased. These results indicated that hydrophobic interaction between the inhibitor molecule and the binding domain should be important and that an anionic form of nitrophenols may be the active form at the binding domain. Hydrogen-bond-acceptable 4-substituents such as methoxy and nitro groups, but not cyano group, were favorable to the inhibitory activity. This result, along with the fact that phenolic OH group was essential for the activity, suggested that nitrophenols occupy the ubiquinone redox site by forming two hydrogen-bond bridges as proposed for natural ubiquinone binding. Although a cyano group is hydrogen-bond-acceptable, hydrogen-bond formation between the 4-cyano group and the binding domain was not suggested. This result and molecular orbital calculation studies on electrostatic potential of the inhibitors suggested that hydrogen-bond donating residue may not be located in the region where the rod-like cyano (C identical to N) bond directs.

Animals↗
PubMed1993

Activation of ATP-sensitive K+ channels by cyclic AMP-dependent protein kinase in cultured smooth muscle cells of porcine coronary artery.

The effects of cyclic AMP-dependent protein kinase on ATP-sensitive K+ channels in cultured smooth muscle cells of the porcine coronary artery were investigated using the patch-clamp technique. Extracellular application of isoproterenol (1mM), a beta agonist, or forskolin (2 x 10(-5)M), an activator of adenylate cyclase, activated these channels in cell-attached patch configurations, which were not blocked by phorbol 12-myristate 13-acetate (10(-6)M), an activator of protein kinase C. Cyclic AMP-dependent protein kinase activated these channels in inside-out patch configurations. These results suggest that cyclic AMP-dependent phosphorylation modulates ATP-sensitive K+ channels, in addition to its well known effects on Ca(2+)-activated K+ channels. The activation of ATP-sensitive K+ channels by cyclic AMP-dependent phosphorylation contributes to hyperpolarization of the membrane and to the relaxation of vascular smooth muscle cells.

Adenosine Triphosphate↗
PubMed1993

Inhibition of electron transport of rat-liver mitochondria by synthesized antimycin A analogs.

A series of antimycin A analogs was synthesized by replacement of a dilactone-ring moiety of natural antimycin A by various alkyl, substituted phenyl, substituted diphenyl ether, or amino acid ester groups. The structure-inhibitory activity relationship was studied with rat-liver mitochondria to identify roles of the dilactone-ring moiety in the inhibitor binding to a Qi reaction center of cytochrome bc1 complex. All derivatives caused further reduction of cytochrome b reduced by succinate and the oxidant-induced reduction, showing that the derivatives inhibited electron transport by interacting with a Qi reaction center. The inhibition tended to increase as the hydrophobicity of the inhibitor increased. The mode of binding of inhibitor molecules to a Qi center, which was reflected in, for example, a sigmoidal titration curve for respiratory inhibition and a time-dependent change in inhibitory activity, varied depending on structure. These results suggested that the role of the dilactone-ring moiety of antimycin A may be not only to support hydrophobic interaction with the binding domain by increasing the hydrophobicity of the molecule, as proposed earlier, but also to regulate close fitting of the salicylic acid moiety to the binding domain.

Animals↗
PubMed1993

The 8;21 chromosome translocation in acute myeloid leukemia is always detectable by molecular analysis using AML1.

The AML1 gene was rearranged in leukemic cells with t(8;21)(q22;q22) or its variant, complex t(8;V;21) translocations from 33 acute myeloid leukemia (AML) patients. The AML1 rearrangement was also detected in three AML patients without t(8;21); two had a normal diploid karyotype, and one had a karyotype of 45,X, - X. The AML1 rearrangement in the t(8;21) breakpoint cluster region was not detected in leukemic cells with cytogenetic abnormalities other than t(8;21), or with normal diploidy obtained from 23 AML patients. Because leukemic cells of the five patients with complex t(8;V;21) translocations had a der(8)t(8;21) chromosome with a break in band 8q22 in common, the juxtaposition of the 5' side of AML1 to a predicted counterpart gene located in the breakpoint region of 8q22 may be an essential step in the leukemogenesis of AML with t(8;21). Our findings show that the 8;21 translocation, its variants, and the masked t(8;21) may all be detectable by the Southern hybridization method using the AML1 probes.

Adolescent↗
PubMed1993

The t(8;21) translocation in acute myeloid leukemia results in production of an AML1-MTG8 fusion transcript.

The t(8;21) translocation is one of the most frequent chromosome abnormalities in acute myeloid leukemia. It has been shown that the t(8;21) breakpoints on chromosome 21 cluster within a single specific intron of the AML1 gene, which is highly homologous to the Drosophila segmentation gene runt. Here we report that this translocation juxtaposes the AML1 gene with a novel gene, named MTG8, on chromosome 8, resulting in the synthesis of an AML1-MTG8 fusion transcript. The fusion protein predicted by the AML1-MTG8 transcript consists of the runt homology region of AML1 and the most part of MTG8, which contains putative zinc finger DNA binding motifs and proline-rich regions constituting a characteristic feature of transcription factors. The MTG8 gene is not expressed in normal hematopoietic cells, whereas AML1 is expressed at high levels. Our results indicate that the production of chimeric AML1-MTG8 protein, probably a chimeric transcription factor, may contribute to myeloid leukemogenesis.

Acute Disease↗
PubMed1993

Deletion of WT1 and WIT1 genes and loss of heterozygosity on chromosome 11p in Wilms tumors in Japan.

Six of 39 sporadic Wilms tumors had gross homozygous or hemizygous WT1 and WIT1 deletions. Two Wilms tumor-aniridia-genitourinary abnormalities-mental retardation syndrome patients had total hemizygous WT1 and WIT1 deletions in both constitutional and nonsporadic type tumor cells. Four of the 8 tumors with WT1 and WIT1 deletions showed loss of constitutional heterozygosity (LOH) for markers limited to the 11p13 region. Seven of 19 Wilms tumors with neither WT1 nor WIT1 deletions also had LOH on 11p; 4 in the 11p15-11p13 region, one in the 11p15 and possibly also 11p13 regions, and two solely in the 11p15 region. Thus, 15 of the 41 Wilms tumors (37%) had WT1 and WIT1 deletions or LOH on 11p, and only 2 of the 27 tumors whose nonneoplastic normal tissues were available for study showed LOH limited to the 11p15 region. None of the 7 non-Wilms childhood renal tumors showed WT1 or WIT1 deletions, or LOH on 11p. These data suggest that Japanese Wilms tumors may be characterized by a higher incidence of the gross WT1 deletion and a lower incidence of LOH limited to the 11p15 region than the Caucasian counterparts. These molecular-genetic features may be contributing to the lower incidence of Wilms tumors in Japanese children than in Caucasian ones.

Blotting, Southern↗
PubMed1993

[Clinical study on postoperative infections caused by methicillin-resistant Staphylococcus aureus after gastrointestinal surgery].

We studied 308 postoperative infections (216 patients) after gastrointestinal surgery during 1987-1991, to elucidate the incidence of postoperative infections caused by methicillin-resistant Staphylococcus aureus (MRSA) and its correlation to clinical background factors. Results were as follows: (1) MRSAs were isolated from 25.9% out of 216 patients or 22.4% out of 308 infections. (2) The isolation rate of MRSA was significantly high in infectious enterocolitis (64.7%, p < 0.001), intraabdominal infections (52.5%, p < 0.001) and respiratory tract infections (35.3%, p < 0.05). On the other hand, it was significantly low in bacteremias (9.28%, p < 0.001), wound infections (13.6%, p < 0.05) and urinary tract infections (3.33%, p < 0.05). (3) MRSAs were found more frequently in male (p < 0.05), younger patients (p < 0.05) and patients with malignant disease (p < 0.10). Whereas no difference was recognized between patients with or without complication. (4) The isolation rate of MRSA by the kind of antibiotics used after surgery, was 0% (0/20, the 1st generation cephems), 17.2% (10/58, the 2nd generation cephems) and 54.5% (48/88, the 3rd generation cephems). Significant differences were found among each group (p < 0.05, p < 0.001). (5) During 1990-1991 when the 1st generation cephems were used frequently, MRSAs were found significantly lower in frequency than during 1987-1989 (p < 0.05). Especially a marked decrease in the rate of MRSA (51.4% to 8.33%, p < 0.05) was seen among patients after upper gastrointestinal surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Mechanistic aspects of the interaction of antisense DNA.

To investigate the mechanism of antisense effects, diastereoisomerism of oligodeoxynucleotides with modified internucleotide phosphate linkages such as oligodeoxynucleoside phosphoramidates (OPA) and oligodeoxynucleoside phosphorothioates (OPT). Reversed-phase HPLC was used to separate the diastereoisomers of OPA (up to tetramer) and OPT (up to pentamer), and it was found that the complete purification of all diastereoisomers could be achieved by the two-step chromatographic approach. From the circular dichroism measurements, it was found that some diastereoisomers formed certain hybrids with their complementary oligonucleotides and some did not.

Chromatography, High Pressure Liquid↗
PubMed1992

Consistent disruption of the AML1 gene occurs within a single intron in the t(8;21) chromosomal translocation.

The AML1 gene on chromosome 21 was rearranged by the t(8;21) chromosomal translocation in acute myeloid leukemia (AML). Southern blot analysis of 21 AML patients with t(8;21), including three with complex translocations, t(8;V;21), demonstrated that all the breakpoints occurred at random within a single intron between two coding exons of AML1. Clustering of the breakpoints in the restricted intron suggests the formation of a unique fusion gene between the AML1 gene and a presumable counterpart gene on chromosome 8. Nucleotide sequencing of the breakpoint region revealed that the translocation event was accompanied by deletion of a short stretch of nucleotides.

Base Sequence↗
PubMed1992

Comparison of structure of quinone redox site in the mitochondrial cytochrome-bc1 complex and photosystem II (QB site).

A series of nitrophenolic electron-transport inhibitors (2-substituted 4,6-dinitrophenols) of rat liver mitochondrial cytochrome-bc1 complex and of photosystem II (QB site) of spinach thylakoids was synthesized. The structure/inhibitory-activity relationship was examined to elucidate differences in the three-dimensional structure of the quinone redox site in the two systems. These inhibitors occupy the ubiquinone redox site of cytochrome-bc1 complex competitively with natural ubiquinol, probably at a Qo reaction center. The inhibitory activity tended to increase with the length of the 2-substituent, which may correspond to the isoprenoid side chain of ubiquinone and plastoquinone, increased in both experimental systems. However, the strict structural requirements of the 2-substituent for binding to the ubiquinone or plastoquinone redox site were not identical. The alkyl substituents with a branching structure at the alpha-position to the benzene ring were favorable for inhibition of the cytochrome-bc1 complex, but not of photosystem II. Molecular-orbital calculations indicated that the main chain of 2-substituents with an alpha-branching structure was almost perpendicular to the benzene-ring plane because of steric congestion between the alpha-methyl and phenolic OH groups. The main chain of 2-substituents without an alpha-branching structure was flexible. Molecular-orbital studies indicated that ubiquinol was most stable when the portion of the isoprenoid side chain adjacent to the quinol ring was perpendicular to the quinol-ring plane, because of steric congestion by the vicinal OH and methyl groups. The side chain of plastoquinol was flexible because of the lack of a vicinal methyl group. Thus, the difference in the inhibitory activities between the two systems seemed to reflect the difference in the configuration of the isoprenoid side chain of ubiquinone and plastoquinone. These results suggested that the quinone redox site of the cytochrome-bc1 complex may recognize the configuration of the side chain near the quinone ring in the strict sense, whereas that of photosystem II (QB site) may recognize it in a loose sense.

Animals↗
PubMed1992

Long-distance restriction mapping of the proximal long arm of human chromosome 21 with Not I linking clones.

Human chromosome 21 is the smallest of the 22 autosomes and 2 sex chromosomes. Hybridization of the human repetitive sequence Alu to pulsed-field gel-fractionated Not I-digested genomic DNA from a human-mouse hybrid cell line containing chromosome 21 as the sole human component identified chromosome 21 Not I restriction fragments. A Not I restriction map of regions of the chromosome was constructed, by identifying neighboring Alu bands with Not I linking clones. This approach simplifies the task of physical mapping and avoids ambiguities in Not I fragment assignments that arise from gel-to-gel mobility variations. A contiguous map was constructed with six Not I linking clones that covers at least the proximal one-third of the long arm of chromosome 21 and spans 20 megabases. A more detailed restriction map revealed 11 likely CpG islands in this region and localized 11 additional DNA markers.

Chromosomes, Human, Pair 21↗
PubMed1992

A packed-bed reactor utilizing porous resin enables high density culture of hepatocytes.

To enable high density culture of hepatocytes for use as a hybrid artificial liver support system or a bioreactor system, a packed-bed reactor using collagen-coated reticulated polyvinyl formal (PVF) resin was applied to a primary culture of hepatocytes. Cubic PVF resins (2 x 2 x 2 mm, mean pore size: 100, 250 or 500 microns) were used as supporting substrates to immobilize hepatocytes. Two hundred and fifty cubes were packed in a cylindrical column, and 2.6-11.3 x 10(7) hepatocytes were seeded in the column by irrigating with 3 ml of the medium containing hepatocytes. Perfusion culture experiments using this packed-bed reactor, as well as monolayer cultures using conventional collagen-coated petri dishes as control experiments, were performed. Sufficient amounts of hepatocytes were found to be immobilized in the reticulated structure of the PVF resins. The highest density of immobilized hepatocytes attained with PVF resin was 1.2 x 10(7) cells/cm3 PVF, which showed levels of ammonium removal and urea-N secretion comparable to those in the monolayer culture. It is concluded that the packed-bed reactor system utilizing PVF resin is a promising process for developing a bioreactor or a bioartificial organ using hepatocytes.

Alanine Transaminase↗
PubMed1992

Uncoupling action of antibiotic sporaviridins with rat-liver mitochondria.

The effects of the glycoside antibiotic sporaviridins (SVDs) on oxidative phosphorylation of rat-liver mitochondria were examined. SVDs released state 4 respiration, dissipated transmembrane electrical potential, and accelerated ATPase activity. These facts demonstrated that SVDs are potent uncouplers of oxidative phosphorylation. During the uncoupling caused by SVDs, large amplitude swelling and oxidation of intramitochondrial NAD(P)H occurred, suggesting that SVDs greatly enhanced nonspecific permeability of the inner mitochondrial membrane. It is suggested that the uncoupling action of SVDs might be caused by dissipation of proton electrochemical potential due to an increase in the permeability of inner mitochondrial membrane.

Aminoglycosides↗
PubMed1992

Accuracy of the results measured by in vivo 1H-MRS using model solutions.

In in vivo 1H-MRS of human brain, main three metabolites such as N-acetyl-L-aspartate (NAA), creatine/phosphocreatine (PCr/Cr), and choline (Cho) have been observed. In this paper an accuracy of the results measured by in vivo 1H-MRS using above model solutions was discussed. 1.0 mmol/l choline and 1.5 mmol/l creatine/phosphocreatine saline solutions were measured with STEAM method (echo time 270 msec). The peak area of Cho was larger than that of PCr/Cr against their concentrations and was linearly increased with its concentration in the range of 5.8 and 29 mumol/27 cm3. Although both peak areas of Cho and Cr/PCr were varied with Volume-of-interest (VOI) coordinates, the ratio of Cho to PCr/Cr was approximately 1.6.

Brain↗
PubMed1992

[Investigation on central venous catheter related sepsis].

We made an investigation on central venous catheter related sepsis (CRS) in recent 5 years (1987-1991). The incidence of CRS was high; 16.0% (125 out of 782 cases) or 13.1% (135 out of 1029 catheters). CRS occurred frequently during 2-3 weeks after catheter insertion. The incidence of CRS was not affected by the kind of disease (malignant or benign), complication (diabetes, liver cirrhosis, collagen disease) operation or administration of antibiotics. Eight percent out of 91 organisms isolated from culture of catheter tips were so-called resistant strains; multi-drug resistant Staphylococci (16), Pseudomonas aeruginosa (5), fungi (49), etc. Complications (shock, acute renal failure, secondary pneumonia, fungal endophthalmitis) broken out in 18 patients (14.4% out of 125 CRS). Fungi were isolated from 14 out of 18 complicated cases, furthermore fungi were isolated alone in 11 cases. No complication were seen among cases from which gram positive cocci were isolated alone. Body temperature and white blood cell count of complicated cases were significantly higher than those of uncomplicated cases. The duration until removal of catheter from outbreak of fever in complicated cases was significantly longer than that in uncomplicated cases.

Candida↗