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Biomedical subjects

M Hatanaka

Publications and source records attributed to M Hatanaka.

At least 217 records · Page 12Linked to original sources
PubMed1990

Synthetic cephalosporins. VII. Synthesis and antibacterial activity of 7-[(Z)-2-(2-aminothiazol-4-yl)-2-(3-(3-hydroxy-4-pyridon-1-yl)-3- carboxypropoxyimino)acetamido]-3-(1,2,3-thiadiazol-5-yl)-thiomethyl-3- cephem-4-carboxylic acid and its related compounds.

Synthesis and antibacterial activity of 7-[(Z)-2-(2-aminothiazol-4-yl)-2-(3-(3-hydroxy-4-pyridon-1-y l)-3- carboxypropoxyimino)acetamido]-3-(1,2,3-thiadiazol-5-yl)thio methyl-3-cephem-4-carboxylic acid (12a) and its related compounds are described. Compound 12a exhibited excellent antibacterial activity against gram-negative bacteria, including Pseudomonas aeruginosa.

Bacteria↗
PubMed1990

Cyclic AMP-mediated inhibition of cell growth by prostaglandin D2 in a fibroblastic cell line (EBTr).

We have recently reported that prostaglandin D2 (PGD2) specifically elevates the intracellular cyclic AMP (cAMP) level in a fibroblastic cell line derived from bovine embryonic trachea (EBTr) (K. Sugama, T. Tanaka, H. Yokohama, M. Negishi, H. Hayashi, S. Ito, and O. Hayaishi, Biochim. Biophys. Acta, 1011: 75-80, 1989). Since the in vitro and in vivo inhibitory effects of PGD2 on cell growth are attributed to the dehydrate product 9-deoxy-delta 9,12-13,14-dihydro-PGD2 (delta 12-PGJ2), the role of cAMP as a mediator of PGD2-induced cell growth has been questioned. In this study we investigated the effects of PGD2 on cAMP level, DNA synthesis, and c-myc expression using EBTr cells growth-arrested by serum starvation. Quiescent EBTr cells synchronously resumed [3H]thymidine incorporation at 12 h after the addition of serum, an incorporation which ended at 21 h. PGD2 at 1 microM inhibited approximately 30% incorporation without any delay of initiation, and it also caused a rapid increase in the cAMP level at a maximum of 10 min. The inhibition of [3H]thymidine incorporation was increased 40-45% by 5 microM 3-isobutyl-1-methylxanthine, a phosphodiesterase inhibitor. The expression of c-myc mRNA induced by serum at 1-4 h was also inhibited by PGD2. Time-course studies support the association between the reduction of c-myc expression and the successive inhibition of DNA synthesis by PGD2. The dose dependency of PGD2 for these three processes correlated well with each other, and the effects were evident at as low as 10 nM and specific for PGD2.(ABSTRACT TRUNCATED AT 250 WORDS)

1-Methyl-3-isobutylxanthine↗
PubMed1990

Frequent expression of myeloid antigen (CD13) on immature T cells in culture.

Leukemic cells from 12 patients with lymphoblastic lymphoma (LBL) and T cell acute lymphoblastic leukemia (T-ALL) were studied to determine the inducibility of myeloid antigens in culture in the presence and absence of 12-O-tetradecanoylphorbol-13-acetate (TPA) in association with discrete phenotypic and genotypic analyses on these cells. The investigation revealed that leukemic cells corresponding to common or mature thymocytes were never induced to express any myeloid antigens, and showed rearrangements of T cell antigen receptor (TcR) beta and gamma chain genes. Concomitant examination on leukemic cells from mature T cell malignancies, including adult T cell leukemia (ATL), T cell chronic lymphocytic leukemia (T-CLL) and T cell non-Hodgkin's lymphoma (T-NHL), also failed to express myeloid antigens in culture. By contrast, one of the panmyeloid antigens, CD13 (MCS-2) antigen was induced on leukemic cells corresponding to early thymocytes in 5 out of 7 cases in TPA-added culture and in 3 cases even in TPA-free culture. All of these CD13 antigen inducible cases exhibited the germ line configurations of TcR beta and gamma chain genes except for one case of T-ALL with sole TcR gamma chain gene rearrangement. These findings suggest that primitive T cells, still not undergoing TcR gene rearrangements, retain the characteristics of multipotent progenitor cells to possess different lineage markers and are able to express myeloid antigen not exceptionally. Both phenotypically and genotypically immature thymocytes are considered to be less restricted in the differentiation pathway of hematopoietic cells committed to T cell lineage.

Antigens, Differentiation, Myelomonocytic↗
PubMed1990

Possible involvement of calpain in down-regulation of protein kinase C.

Calpain is known to play a variety of cellular functions in various cells by Ca2(+)-dependent limited proteolysis. Protein kinase C (PK-C) is a key enzyme in signal transduction. It is known that treatment of a cell with 12-0-tetradecanoylphorbol 13-acetate (TPA) causes down-regulation of PK-C, and that calpain can cleave PK-C into catalytic and regulatory fragments in vitro. In vivo involvement of calpain in down-regulation of PK-C was studied with neuroblastoma cells using various drugs, a synthetic peptide fragment of calpastatin and inhibitors against calpain. TPA-dependent down-regulation of PK-C was partially inhibited by pre-treatment with calpastatin peptide and inhibitors, suggesting in vivo involvement of calpain in down-regulation of PK-C during signal transduction.

Amino Acid Sequence↗
PubMed1990

Gene expression for calpain isozymes in human hematopoietic system cells.

Calpain (EC 3.4.22.17; Ca2(+)-dependent cysteine endopeptidase) is known to exist in two forms of isozyme. Calpain I requires low (or microM)-Ca2+ for activation and calpain II requires high (or mM)-Ca2+. Both isozymes consist of one heavy (approx.80 kDa) and one light (approx. 30 kDa) subunit each. The heavy subunits of isozymes I and II are different genetic products, while the light subunits are identical. Antibodies respectively specific for the heavy subunits of pig calpains I and II were raised in rabbits, and the affinity-purified IgG proteins were used for Western blot analysis. When 23 human hematopoietic system cells were examined for the degree of their expression of the genes for calpains I and II, all of them were found to contain calpain I of detectable amounts in their cytosolic fluid. By contrast, only nine cell-line cells were positive in calpain II, and they were, without exception, the lineage which had been infected with HTLV-I, the retrovirus responsible for human adult T-cell leukemia. The enhanced production of calpain II in HTLV-I infected T-cells was also confirmed by running chromatographic analyses on the homogenates of these cells, and comparing them with those of uninfected T-cells. When YT-C3 cell, which is an uninfected, natural killer-like cell, was transfected with HTLV-I gene, the resulting transformed stable cells, YT-4 and YT-5.1, were found to produce increased amounts of calpain II concomitant with that of interleukin (IL)-2 receptor protein. These results suggest that the gene expression for calpain isozymes may vary during the course of differentiation of T-lymphocytes. The mechanism of regulation of calpain isozyme genes and the biological significance of the variation in expression during differentiation still remain unanswered.

Animals↗
PubMed1990

Factors influencing the binding of calpain I to human erythrocyte inside-out vesicles.

The mechanism for binding of human erythrocyte calpain I to human erythrocyte inside-out vesicles was studied by immunoelectrophoretic blot analysis. Binding of calpain I to inside-out vesicles was observed both in the absence and presence of Ca2+. Moreover, in the absence of Ca2+, acidic proteins like casein, ovalbumin and calpastatin suppressed while basic proteins like arginase and lysozyme did not affect the binding of calpain I to inside-out vesicles. Here, we propose a model for the binding of calpain to the membrane.

Arginase↗
PubMed1989

Inhibition of calpain by a synthetic oligopeptide corresponding to an exon of the human calpastatin gene.

Calpastatin is a widely distributed endogenous inhibitor protein specifically acting on calpain (Ca2+-dependent cysteine endopeptidase). The inhibitor consists of four inhibitory domains (Domains 1-4) with mutually homologous sequences. NH2-terminal Domain L is non-homologous, and all domains have 120-140 residues each. A human calpastatin genomic DNA clone was isolated using a previously obtained human calpastatin cDNA probe. Sequence analysis has revealed that the clone contains Domain 1 and segments of neighboring domains (Domains L and 2). Each of three highly conserved, restricted regions within Domain 1 was located on separate exons, 1A, 1B, and 1C. Exon 2A, corresponding to the first exon of Domain 2, is homologous to Exon 1A and follows Exon 1D of Domain 1. A 27-residue peptide encoded by Exon 1B, including a 12-residue middle conserved sequence, was chemically synthesized and tested for protease inhibitory activities. The synthetic peptide showed strong inhibition against calpain I (low Ca2+-requiring form), and calpain II (high Ca2+-requiring form), but no inhibition against papain or trypsin. These results indicated that Exon 1B forms a self-sufficient functional subdomain of the calpastatin inhibitory domain.

Amino Acid Sequence↗
PubMed1989

Functional similarity of HIV-I rev and HTLV-I rex proteins: identification of a new nucleolar-targeting signal in rev protein.

We have tested the functional compatibility between rev protein of human immunodeficiency virus type I (HIV-I) and rex protein of human T-cell lymphotropic virus type I (HTLV-I). Each protein recognized the other's cis-acting sequence, albeit at reduced levels. Both proteins localize predominantly in the nucleolus. We have identified a new nucleolar-targeting signal in rev protein, which was homologous to that of rex protein. The sequence [35-RQARRNRRRRWRERQR-50] in rev protein, when fused to the amino-terminus of beta-galactosidase, directed the hybrid protein to the cell nucleolus. A deletion mutant which lacks several amino acid residues within the signal failed to function in the CAT assay system. These results demonstrate that the nucleolar targeting signals are essential for the functions of Rev and Rex.

Amino Acid Sequence↗
PubMed1989

Differential expression of N-myc and c-src proto-oncogenes during neuronal and schwannian differentiation of human neuroblastoma cells.

Neuroblastoma (NB) cells can be induced to differentiate bidirectionally into either neuronal or schwannian cells by different inducers. However, the underlying mechanisms are poorly understood. We examined the expression of N-myc and c-src genes in 3 human NB-cell lines during either neuronal or schwannian differentiation in vitro, since proto-oncogenes are considered to play a pivotal role in regulating cell proliferation and differentiation. Decreased N-myc expression and increased c-src expression were observed during neuronal differentiation by retinoic acid, polyprenoic acid (E5166) and dibutyryl cyclic AMP, whereas the expression of N-myc and c-src genes was considerably reduced during schwannian differentiation by bromodeoxyuridine, demonstrating that the expression of N-myc and c-src genes was regulated independently in the bipolar differentiation processes of NB cells. Our results suggest that enhanced N-myc expression might be closely linked to the undifferentiated phenotypes of NB cells, that c-src expression might be related to the neuronal differentiation of NB cells, and that N-myc and c-src genes might be regulated independently in the determination of the bipolar differentiation of NB cells.

Cell Differentiation↗
PubMed1989

Low-titer antibodies reactive with HTLV-I gag p19 in patients with chronic myeloneuropathy.

To elucidate the possible association of human T-lymphotropic virus type I (HTLV-I) and chronic neurological diseases, 156 serum samples from patients with various neurological diseases, including multiple sclerosis, chronic progressive myelopathy, chronic inflammatory polyradiculoneuropathy, myasthenia gravis, polymyositis, motor neuron disease, and tension headache, and healthy control subjects were examined for IgG antibodies to HTLV-I by three independent techniques--gelatin particle agglutination test, enzyme-linked immunosorbent assay, and Western blot assay. Specificity of antibodies was assessed by homologous competitive inhibition on Western blot assay. Six patients (3 with chronic progressive myelopathy, 1 with chronic inflammatory polyradiculoneuropathy, 1 with motor neuron disease, and 1 with tension headache) had high-titer HTLV-I antibodies. Twelve patients (5 with multiple sclerosis, 1 with chronic progressive myelopathy, 2 with chronic inflammatory polyradiculoneuropathy, 2 with myasthenia gravis, and 2 with motor neuron disease) had low-titer HTLV-I antibodies that reacted with a single gag protein, p19 or p24, on Western blot assay. In 4 (2 with multiple sclerosis, 1 with chronic progressive myelopathy, and 1 with chronic inflammatory polyradiculoneuropathy) of these 12, the antibodies that were all directed to p19 were determined to be specific by homologous competitive inhibition. In the remaining 8 patients (3 with multiple sclerosis, 1 with chronic inflammatory polyradiculoneuropathy, 2 with myasthenia gravis, and 2 with motor neuron disease), restricted reactions against p19 or p24 were considered to be nonspecific because they were not inhibited by homologous competitive inhibition. The results suggest that in some patients chronic myeloneuropathy diagnosed as chronic progressive multiple sclerosis, chronic progressive myelopathy, and chronic inflammatory polyradiculoneuropathy may be associated with HTLV-I or related retroviruses.

Adolescent↗
PubMed1989

Identification of HTLV-I gag protease and its sequential processing of the gag gene product.

The full-length provirus of human T-cell leukemia virus type I (HTLV-I) was isolated from MT-2, a lymphoid cell line producing HTLV-I. In transfected cells, structural proteins of HTLV-I, the gag and env products, were formed and processed in the same manner as observed in MT-2 cells. The nucleotide sequence was determined for a region between the gag and pol genes of the proviral DNA clone containing an open-reading frame. The deduced amino acid sequences show that this open-reading frame encodes a putative HTLV-I protease. The protease gene (pro) of HTLV-I was investigated using a vaccinia virus expression vector. Processing of 53k gag precursor polyprotein into mature p19, p24, and p15 gag structural proteins was detectable with a recombinant plasmid harboring the entire gag- and protease-coding sequence. We demonstrated that the protease processed the gag precursor polyprotein in a trans-action. A change in the sequence Asp(64)-Thr-Gly, the catalytic core sequence among aspartyl proteases, to Gly-Thr-Gly was shown to abolish correct processing, suggesting that HTLV-I protease may belong to the aspartyl protease group. The 76k gag-pro precursor polyprotein was identified, implying that a cis-acting function of HTLV-I protease may be necessary to trigger the initial cleavage event for its own release from a precursor protein, followed by the release of p53 gag precursor protein. The p53 gag precursor protein is then processed by the trans-action of the released protease to form p19, p24, and p15.

Amino Acid Sequence↗
PubMed1989

The calpain-calpastatin system in hematopoietic cells.

Calpain I requires low Ca2+ for activation and calpain II requires high Ca2+. It was generally accepted that erythrocytes contain calpain I and calpastatin, but no calpain II. We have recently found, however, that nucleated chicken erythrocytes contain both calpains I and II in addition to calpastatin. The finding is significant in rectifying the previous view that the chicken has only one molecular species of calpain, whereas mammals have two. Another erroneous view which prevailed previously was that polymorphonuclear (PMN) cells contain only one calpain species. We could also recently demonstrate that pig PMN cells do contain both calpains I and II. The cloning of cDNAs for calpastatin enabled us to utilize them as the probes in studying the expression of calpastatin in various hematopoietic cell-line cells. We found that several T cells infected with human retrovirus HTLV-I markedly increased the production of calpastatin, which could be measured both by calpain-inhibition assay and by Western blot analysis, but the level of mRNA for calpastatin did not significantly change when compared with noninfected T cells. The increase in calpastatin protein always parallels with the expression of interleukin 2 receptor protein by the HTLV-I-infected T cells, although the biological implication of such phenomena is almost entirely unknown yet.

Animals↗
PubMed1989

A region of basic amino-acid cluster in HIV-1 Tat protein is essential for trans-acting activity and nucleolar localization.

The trans-acting factor of human immunodeficiency virus (HIV), Tat, has a basic amino-acid cluster that is highly conserved among different HIV isolates. We have examined the effects of mutations in the basic region of Tat on its trans-acting activity and cellular localization. Introduction of a stop codon immediately preceding the basic region abolished the activity, while the truncated mutant with the basic region retained some activity. The basic region of Tat was replaceable with that of Rev (another trans-acting factor of HIV) but not with that of adenovirus Ela nor cellular enzyme. The result of immunofluorescence analysis revealed a correlation between the nuclear, especially nucleolar, accumulation and the activities of mutant Tat proteins.

Amino Acid Sequence↗
PubMed1989

Expression of post-transcriptional regulatory gene of HTLV-I, rex, in Escherichia coli.

Human T-cell leukemia virus type-I (HTLV-I) has a post-transcriptional regulatory gene termed rex. We have designed the rex gene to express in E. coli. Synthesis of rex protein, p27rex, was examined by immunoblot analysis using anti-p27rex antibody. No difference in electrophoretic mobility in NaDadSO4-PAGE was observed between p27rex expressed in E. coli and in an HTLV-I-infected cell line, MT-2. Slower migration of p27rex, corresponding to a 27-kD protein, in NaDodSO4-PAGE when compared with the calculated molecular weight from the amino acid sequence (Mr = 20,367) is suggested to be caused not by post-translational modification, but by the intrinsic nature of the protein, which is rich in proline and arginine.

Escherichia coli↗
PubMed1989

Role of the cysteine-rich region of HIV tat protein on its trans-activational ability.

The tat protein of human immunodeficiency virus (HIV) has a characteristic cysteine-rich region containing 7 cysteines within 16 residues. The role of this region was investigated by creation of several tat gene mutants. The activities of the novel tat gene translational products were assayed by measuring the co-transfected chloramphenicol acetyl-transferase (CAT) gene expression controlled by HIV long-terminal repeat (LTR) in the COS 7 cells. Substitution of either Cys22 with Gly, or Cys34-Gln-Val-Cys with His-Gln-Val-His, and deletion behind Lys50 of the tat protein caused a drastic loss in its activity.

Amino Acid Sequence↗
PubMed1989

Binding of cellular protein(s) to U3 region of human T-cell leukemia virus type-I long terminal repeat.

The U3 region within the long terminal repeat (LTR) of human T-cell leukemia virus type-I (HTLV-I) contains elements responsible for transcriptional trans-activation. DNA-binding activities of nuclear proteins for each region of LTR were demonstrated using the gel retardation assay. The existence of cellular protein(s) specifically binding to the U3 region was demonstrated. Furthermore, the formation of the U3-protein(s) complex increased remarkably in HTLV-I-infected T-cells.

Cell Nucleus↗