Search PubMed⌕ Search

Biomedical subjects

Y Hashimoto

Publications and source records attributed to Y Hashimoto.

At least 757 records · Page 42Linked to original sources
PubMed1995

Cytotoxicity and DNA-binding property of non-diynene class of dynemicins and aza-anthraquinones.

Dynemicin A is a potent antibacterial and antitumor antibiotic having a striking hybrid structure of both anthraquinone as a DNA intercalator and diynene as a DNA strand breaker. We have investigated the DNA-binding property and cytotoxicity of non-diynene class of dynemicins (H, L, M, O and Q) and several related synthetic tri- and pentacyclic aza-anthraquinones 1a-3a (R = H) and 1b-3b (R = CH3). Among them, dynemicin H, L, M, O, Q, 1a, 1b and 2b exhibited DNA-binding property. All non-diynene class of dynemicins investigated exhibited intercalative binding activity, however, synthetic aza-anthraquinones 1a-3a did not show such ability. Dynemicin H, Q, 2a, 2b and 3b showed cytotoxicity against HL-60 and K-562 cell lines.

Alkenes↗
PubMed1995

[A consideration in regard to 16 patients died at home].

We had given the service to the patients who desired home care. And now we made inquiries about 16 cases died at home. They were satisfied with our service and death at home. But in regard to the question "If you die at home, Are you satisfied?¿, half the number answered "NO". We should recognize the present condition that we can not fulfill the needs of patients and their families.

Adult↗
PubMed1995

[Medical economy of home care in private hospital].

In order to analyze the economics of home care, we calculated the revenue and expenditures of both hospitalization and home care in a private hospital. The home care expenses were about 44.7% of the institutional care expenses. It became clear that home care saved medical expenses. The expenses of patients were about 33.7% less with home care. In conclusion, home care may be favorable medical care if some problems are solved. The home care expenses of a cancer patient on the institutional side were about 3.4 times more that those of a patient with other diseases. If we support home care of cancer patients alone, it would be an excessive burden on them, because patients are too few at present to organize and keep a team. As a private hospital, we support home care regardless of disease. However, medical economic expenses as a total turned out to be about 17% short of the necessary expenses.

Aged↗
PubMed1994

Tumor necrosis factor alpha production enhancers with a phenylphthalimide skeleton.

N-2,6-Dialkylphenylphthalimides were found to be strong enhancers of 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced tumor necrosis factor (TNF)-alpha production by human leukemia cell line HL-60. Among these compounds, 2-(2,6-diisopropylphenyl)-1H-isoindole-1,3-dione (PP-33) showed the most potent activity (optimum concentration of 10 microM), indicating that the bulkiness of the alkyl groups at the 2 and 6-positions of the phenyl ring moiety is crucial for the activity. Its fluorinated derivative, 2-(2,6-diisopropylphenyl)-4,5,6,7-tetrafluoro-1H-isoindole-1,3-dio ne (FPP-33) showed the activity at very low concentrations (optimum concentration of 0.1 microM).

Humans↗
PubMed1994

Endocytosis does not necessarily augment the cytotoxicity of adriamycin encapsulated in immunoliposomes.

We studied the relationship between endocytosis and cytoxicity of adriamycin (ADM) encapsulated in antibody-coated liposomes (immunoliposomes, IL) which are called chemoimmunoliposomes (CIL), by using several human cancer cell lines. IL coated with a monoclonal antibody, HBJ127 (IgG), which recognizes human gp125 antigen, specifically bound to gp125-positive target cancer cell lines, KU-1, T24, MKN-7, SKBr-3 and LS174T. Flow cytometric analysis using IL encapsulating carboxyfluorescein (CF) revealed that efficiencies of endocytosis varied among different cancer cells. The rate of IL internalization was in the order KU-1 > T24 > MKN-7 > SKBr-3 > LS174T. In 1 h incubation at 37 degrees C, all the four cell lines other than LS174T internalized about 60% of IL which were bound on their cell surfaces. KU-1, T24 and MKN-7, but not SKBr-3, significantly processed IL in endosome or lysosome. On the contrary, 80% of CIL bound to LS174T remained on the cell surface even after 2 h incubation. Furthermore, we evaluated the cytotoxic activities of CIL against the same panels of cancer cells. CIL inhibited the growth of all cancer cells tested in antibody-dependent manner, but, contrary to our expectation, KU-1 and T24 cells, which showed significant endocytosis activity, required a 7-14-fold higher amount of ADM binding than LS174T cells with low endocytosis activity for 50% cell growth inhibition. The difference of sensitivity to free ADM was only within 2.3-fold among those cancer cells. These results showing that liposomal ADM endocytosed is less effective than that remaining on the cell surface suggest that endocytosis is not necessarily required for cytotoxicity of CIL.

Antigens, Neoplasm↗
PubMed1994

Purification and characterization of UDP-GlcNAc:IV3 beta Gal-Gb4Cer beta-1,6-GlcNAc transferase from mouse kidney.

The Gsl-5 gene mapped on mouse chromosome 19 controls the expression of IV6 beta Gal beta 1-4(Fuc alpha 1-3)GlcNAc, IV3 beta Gal-Gb4Cer in mouse kidney through regulation of the activity of UDP-GlcNAc:IV3 beta Gal-Gb4Cer beta-1,6-Glc-NAc transferase (GNT), which transfers GlcNAc to the C-6 position of GalNAc of IV3 beta Gal-Gb4Cer (GL-X). Here we report that GNT has been purified to apparent homogeneity from mouse kidney by means of preparation of a microsomal fraction, solubilization with Triton X-100, and sequential column chromatographies on CM-Sepharose, UDP-hexanolamine-Sepharose, and Gg4Ose-Aminocellulo-fine. GNT purified 11,000-fold from the microsomal fraction exhibited a specific activity of 26.15 mumol/min/mg protein and an apparent molecular mass of 50 kDa on SDS-polyacrylamide gel electrophoresis. The Km values for UDP-GlcNAc and GL-X were 0.36 and 0.11 mM, respectively. Among glycolipids tested as substrates, GL-X was the best and Gg4Cer the next best, but Lc3Cer, Gb4Cer, and GM1 did not act as a substrate. GNT was also able to transfer GlcNAc to Gal beta 1-3GalNAc beta 1-benzyl and Gal beta 1-3GalNAc alpha 1-p-nitrophenyl at C-6 of GalNAc through beta linkage but not to GlcNAc beta-3GalNAc alpha 1-p-nitrophenyl. The purified GNT was digested with lysyl endopeptidase, and four peptides generated were sequenced. The sequence of four peptides spanning 35 amino acid residues in total exhibited 80% homology with that of the reported human core 2 GlcNAc transferase.

Amino Acid Sequence↗
PubMed1994

Roles of myosin light-chain kinase in platelet shape change and aggregation.

We examined the roles of myosin light-chain kinase in platelet responses to ADP using wortmannin, which almost completely inhibited myosin light-chain kinase at 3-6 microM. This concentration of wortmannin did not affect ADP-induced changes in the shape of the platelets, but it markedly inhibited aggregation in platelet-rich plasma and washed platelets. ML-9, another inhibitor of myosin light chain kinase, elicited similar effects on the platelet responses to wortmannin. Electron microscopic studies showed that there was no wortmannin effect on the ADP-induced spheration of discoid platelets, pseudopod formation, or granule centralization. Wortmannin at concentrations which prevented myosin light-chain kinase also inhibited platelet aggregation induced by ADP in the presence of U46619, an analogue of thromboxane A2, which is a prerequisite for ADP-induced irreversible aggregation. Although wortmannin partially inhibited protein kinase C, the protein kinase C inhibitor Ro-31-7549 (5 microM) prevented neither ADP- or ADP/U46619-induced changes in the shape of the platelets nor aggregation. These results suggest that myosin light-chain kinase activation is a prerequisite for ADP-induced platelet aggregation, but not for changes in their shape.

Adenosine Diphosphate↗
PubMed1994

Functional evidence for an apical ANP receptor in LLC-PK1 kidney epithelial cells.

The localization of natriuretic peptide receptors was studied in LLC-PK1 cell monolayers grown on a micro-porous membrane filter. The addition of alpha-human atrial natriuretic peptide (alpha-hANP) to the apical side of the cells produced a concentration-dependent increase in cyclic GMP (cGMP) formation, the extent of which was similar to that produced by the addition to the basolateral side. More cGMP was formed with alpha-hANP (1 and 100 nM) than with the C-type natriuretic peptide (100 nM). These findings indicate that the biologically active receptors with high efficacy for alpha-hANP are expressed in both the apical and basolateral membranes in LLC-PK1 cells.

Animals↗
PubMed1994

Prostaglandin F2 alpha enhances tyrosine phosphorylation and DNA synthesis through phospholipase C-coupled receptor via Ca(2+)-dependent intracellular pathway in NIH-3T3 cells.

Previously, we characterized the prostaglandin (PG) F2 alpha receptor linked to phospholipase C activation and DNA synthesis in NIH-3T3 cells (Nakao, A., Watanabe, T., Taniguchi, S., Nakamura, M., Honda, Z-I., Shimizu, T., and Kurokawa, K. (1993) J. Cell. Physiol. 155, 257-264). To elucidate intracellular events evoked via this receptor, we examined changes caused by PGF2 alpha stimulation in the phosphotyrosine composition of cellular proteins. The addition of PGF2 alpha to cells in quiescent culture rapidly increased the levels of phosphotyrosine in cellular proteins with Mr values of 70,000 (pp70), 85,000 (pp85), 92,000 (pp92), 100,000 (pp100), and 125,000 (pp125); the latter was immunologically identified as p125 focal adhesion kinase. The PGF2 alpha-induced changes in the level of intracellular Ca2+ ([Ca2+]i) elevation, formation of inositol phosphates, and [3H]thymidine incorporation followed a similar dose dependence as PGF2 alpha-induced tyrosine phosphorylation. This tyrosine phosphorylation was independent of extracellular Ca2+, while a [Ca2+]i chelator, 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (50 microM), completely inhibited the PGF2 alpha-induced elevation of [Ca2+]i, tyrosine phosphorylation, and [3H]thymidine incorporation. Ionomycin (0.1 microM), which induced [Ca2+]i elevation without formation of inositol phosphates, mimicked the PGF2 alpha-induced tyrosine phosphorylation. 12-O-Tetradecanoylphorbol-13-acetate (TPA) also induced [3H]thymidine incorporation in a dose-dependent manner but had no significant effect on tyrosine phosphorylation. The PGF2 alpha-induced tyrosine phosphorylation could be observed even in the cells pretreated with TPA (5 microM, 24 h). PGF2 alpha exhibited an additive effect on TPA-induced [3H]thymidine incorporation but had no effect on the 32P-phosphorylation of a known 80-kDa protein kinase (PK) C substrate. Both staurosporine and H-7 inhibited the PGF2 alpha-induced increase in [3H]thymidine incorporation and tyrosine phosphorylation in a similar dose-dependent manner whether or not cells were pretreated with TPA (5 microM, 24 h). However, W-7 and KN-62 had no effect on these cellular responses even at the concentration for the almost complete inhibition of Ca2+/calmodulin-dependent PKs (20 microM). These results, taken together, indicate that PGF2 alpha receptor-mediated tyrosine phosphorylation is evoked by a [Ca2+]i-dependent mechanism that is sensitive to staurosporine and H-7 but which is independent of PKC or Ca2+/calmodulin PKs. Finally, the data suggest that this PGF2 alpha-induced signaling pathway is linked to the proliferation of cells.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1994

Protein kinase C-dependent and -independent mechanisms of dense granule exocytosis by human platelets.

We examined the mechanisms of ATP release by human platelets using Ro-31-7549, a specific inhibitor of protein kinase C. Ro-31-7549 almost completely inhibited TPA-induced platelet aggregation and ATP release at 5-10 microM in washed platelets and in platelet-rich plasma. However, it suppressed thrombin- and U46619-induced ATP release by only 48% and 21%, respectively, and had little effect on aggregation in washed platelet suspensions containing serum or in platelet-rich plasma. The addition of GRGDS to prevent aggregation inhibited this residual thrombin-induced release by 53% and the residual U46619 release by 100% in the presence of Ro-31-7549. In washed platelet suspensions free of serum or plasma, Ro-31-7549 almost completely inhibited the ATP release and partially suppressed the aggregation induced by these agonists. These results suggested that there are protein kinase C-dependent and -independent mechanisms for ATP release by human platelets and that activation of the latter mechanism may depend on aggregation and plasma factors.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1994

Retinobenzoic acids. 6. Retinoid antagonists with a heterocyclic ring.

Several candidate retinoid antagonists were designed on the basis of the ligand superfamily concept and synthesized. Retinoidal activities of these benzimidazole and benzodiazepine derivatives were examined by assay of differentiation-inducing activity on human promyelocytic leukemia cell line HL-60. The parent benzimidazole derivative, 4-(5,6,7,8-tetrahydro-5,5,8,8- tetramethylnaphth-[2,3-d]imidazol-2-yl)benzoic acid (7a), and related compounds with a small alkyl group instead of the hydrogen on the nitrogen (1N) atom of the imidazole ring exhibited retinoidal activity, and the potency strongly depended on the bulkiness of the substituent. The compounds having a phenyl or benzyl group on the nitrogen lacked differentiation-inducing activity on HL-60 cells and acted as antagonists to the potent retinoid 4-[(5,6,7,8-tetrahydro-5,5,8,8- tetramethyl-2-naphthalenyl)carbamoyl]benzoic acid (Am80). Among the compounds possessing a seven-membered heterocyclic ring as a linking group, 4-(5H-7,8,9,10-tetrahydro-5,7,7,10,10- pentamethylbenzo[e]- naphtho[2,3-b][1,4]diazepin-13-yl)benzoic acid (16) also exhibited the antagonistic activity. The binding abilities of these compounds to retinoic acid receptors alpha and beta were consistent with their potency for the inhibition of HL-60 cell differentiation induced by the retinoid Am80.

Benzimidazoles↗
PubMed1994

Ionic lead, a unique metal ion as an inhibitor for cytochrome P450IA2 (CYP1A2) expression in the rat liver.

Male F344 rats were treated with lead nitrate, nickel chloride, cobalt chloride or cadmium chloride, and changes in the expression of cytochrome P450IA2 (CYP1A2) in the livers were assessed by enzymatical, immunochemical, and molecular biological methods. All ionic metals used significantly decreased total CYP amount in the liver microsomes. However, among ionic metals used only lead showed inhibitory effects on the microsomal activity for CYP1A2-dependent mutagenesis of aromatic amines and on the expression of mRNA and protein of the enzyme, indicating that ionic lead is a unique inhibitor for the expression of CYP1A2 enzyme in the rat liver.

Animals↗
PubMed1994

DNA adduct formation of hepatocarcinogenic aromatic amines in rat liver: effect of cytochrome P450 inducers.

F344 rats were treated with an i.p. injection of 2-amino-6- methyldipyrido[1,2-a:3',2'-d]imidazole (Glu P-1) or 3-methoxy-4-aminoazobenzene (3-MeO-AAB) and examined for the formation of the DNA adduct in the liver. To examine the effect of pretreatment with a cytochrome P450 (CYP) inducer on the formation of DNA adduct, these rats were pretreated with 3-methylcholanthrene (MC; CYP1A1/1A2 inducer) or phenobarbital (PB; CYP2B inducer). Administration of Glu P-1 and 3-MeO-AAB gave 2 and 5 adducts, respectively, as determined by 32P-postlabeling assay. By Glu P-1 administration, pretreatment of rats with MC, but not with PB, increased the total amount of DNA adducts including 3 new adducts as minor products. In contrast, pretreatment of rats with PB increased the total amount of DNA adducts derived by 3-MeO-AAB. The increase of aromatic amine DNA adducts by pretreatment with a CYP inducer was proportional to the activity of induced CYP isozyme(s) responsible for the mutagenic activation of each aromatic amine.

Animals↗
PubMed1994

C3G, a guanine nucleotide-releasing protein expressed ubiquitously, binds to the Src homology 3 domains of CRK and GRB2/ASH proteins.

CRK protein, together with GRB2/ASH and Nck proteins, belongs to the adaptor-type Src homology (SH)2-containing molecules, which transduce signals from tyrosine kinases. Here another guanine nucleotide-releasing protein (GNRP), C3G, has been identified as a CRK SH3-binding protein. The nucleotide sequence of a 4.1-kb C3G cDNA contains a 3.2-kb open reading frame encoding a 121-kDa protein, and antibodies against C3G have been shown to detect a protein of 130-140 kDa. The carboxyl terminus of C3G has a peptide sequence homologous to GNRPs for Ras, and the expression of this carboxyl terminus region suppresses the loss of CDC25 function in the yeast Saccharomyces cerevisiae. The C3G protein expressed in Escherichia coli binds to CRK and GRB2/ASH proteins. Mutational analysis of C3G assigns the SH3 binding region to a 50-amino acid region containing a proline-rich sequence. The mRNAs of both the C3G and CRK proteins are expressed ubiquitously in human adult and fetal tissues. The results of these studies suggest that the complex of CRK and C3G, or GRB2/ASH and C3G, may transduce the signals from tyrosine kinases to Ras in a number of different tissues.

Adaptor Proteins, Signal Transducing↗
PubMed1994

Enhancement of phorbol ester-induced production of tumor necrosis factor alpha by thalidomide.

The effect of thalidomide [racemic (DL-) form and optically pure (D- and L-) forms] on tumor necrosis factor (TNF) alpha production by human leukemia cell lines (HL-60, K562 and U937) stimulated with 12-O-tetradecanoylphorbol-13-acetate (TPA) was investigated. Though thalidomide has been regarded as a specific inhibitor of TNF-alpha production, our study indicated that all forms of thalidomide enhanced (but did not inhibit) the TPA-induced TNF-alpha production by the human leukemia cell lines investigated. The effects of thalidomide on TNF-alpha production might be cell type-specific.

Cell Line↗