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Biomedical subjects

T Okazaki

Publications and source records attributed to T Okazaki.

At least 217 records · Page 12Linked to original sources
PubMed1995

A novel monoclonal antibody, KOR-SA3544 which reacts to Philadelphia chromosome-positive acute lymphoblastic leukemia cells with high sensitivity.

A monoclonal antibody which primarily reacted with Philadelphia chromosome (Ph1)-positive ALL cells was produced. The reactivity of a monoclonal antibody, KOR-SA3544 (IgG2a) was evaluated on normal hemopoietic cells, 68 leukemic cell lines and freshly obtained cells from 190 patients with leukemia and lymphoma. In cultured cells, KOR-SA3544 reacted with Ph1-positive ALL cell lines (5/5) and leukemic cell lines with 11q23 translocation (3/11). In lymphoid cells, KOR-SA3544 was reactive with all of Ph1-positive ALL (26/26), a part of common ALL (5/38) and one case of early B precursor leukemia with 11q23 translocation, but not with peripheral lymphocytes. Normal mature granulocytes were also strongly stained. In myeloid leukemias, KOR-SA3544 was positive (16/56) only in patients with acute myeloid leukemia with FAB-M2 and overt leukemia following myelodysplastic syndrome, but neither with other types of myeloid leukemias nor with blast crisis in chronic myelogenous leukemia. KOR-SA3544 recognized a 90 KDa protein on the membrane of a leukemic cell line, KOPN-57bi. In normal bone marrow, CD19+/KOR-SA3544+ cells were not identified, while Ph1-positive ALL cells were strongly positive for both antibodies. KOR-SA3544 is useful not only for making the diagnosis of Ph1-positive ALL but for detection of the minimal residual disease during remission.

Antibodies, Monoclonal↗
PubMed1995

BONSAI Garden: parallel knowledge discovery system for amino acid sequences.

We have developed a machine discovery system BONSAI which receives positive and negative examples as inputs and produces as a hypothesis a pair of a decision tree over regular patterns and an alphabet indexing. This system has succeeded in discovering reasonable knowledge on transmembrane domain sequences and signal peptide sequences by computer experiments. However, when several kinds of sequences are mixed in the data, it does not seem reasonable for a single BONSAI system to find a hypothesis of a reasonably small size with high accuracy. For this purpose, we have designed a system BONSAI Garden, in which several BONSAI's and a program called Gardener run over a network in parallel, to partition the data into some number of classes together with hypotheses explaining these classes accurately.

Algorithms↗
PubMed1995

[Treatment of aneurysm of aortic arch using selective cerebral perfusion].

The objective of this study is to evaluate safety and efficacy of the selective cerebral perfusion (SCP) for an adjunct to perform operation of aortic arch aneurysms. From November 1982 to June 1993, surgical treatment of aneurysm of aortic arch using SCP was performed in 22 patients. The hospital death was accounted in 5 cases (23%), the intraoperative stroke was observed in 3 cases (14%) and these patients died. The cause of intraoperative stroke was cerebral hypoperfusion due to multiple sclerosis of intracranial arteries or insufficient SCP. Variables of an increased operative risk seemed to be older age (over 70 y.o.) and rupture. SCP time more than 120 minutes did not promote the operative risk. Cerebral hypoperfusion was directly responsible for not only intraoperative stroke, but also operative death. Therefore, SCP seems effective and safe if hypoperfusion is prevented.

Aged↗
PubMed1995

Stromal cell-mediated transcriptional regulation of the CD13/aminopeptidase N gene in leukemic cells.

CD13/aminopeptidase N (APN) is a cell surface metallopeptidase expressed by normal and leukemic myeloid cells, and by lymphoblasts in 5-10% of acute lymphoid leukemia (ALL) cases, previously classified as 'biphenotypic' or 'mixed-lineage' leukemias. In fresh cells from two early B-lineage, t(9;22)-positive, ALL cases that were CD13/APN-negative at diagnosis, high levels of CD13/APN expression were induced after 3 days of in vitro culture. Similarly, continuously growing cell lines established from these ALLs, KOPN-30bi and KOPN-57bi, expressed CD13/APN, but retained other phenotypic, cytochemical and molecular features of early B-lineage cells. After 7 days of culture on human bone marrow stromal layers or murine S17 stromal cells, levels of CD13/APN expression by the leukemic cell lines decreased by more than 4-fold. After 21 days of culture on stromal cells, CD13/APN became undetectable by flow cytometry; however, the original levels of expression were regained when the cell lines were cultured without stroma. A more moderate decrease in CD13/APN expression was also observed in the myeloid lines KG-1 and HL-60 during culture on stroma. Suppression of CD13/APN expression required contact with stroma, but did not depend on VLA-4-mediated adhesion. Surprisingly, the mechanism through which stromal cells down-regulated CD13/APN expression in leukemic cells involved suppression of transcription from the CD13/APN gene. Contact with stroma resulted in a 2-3-fold decrease in CD13/APN mRNA expression and near ablation of CD13/APN gene transcription in nuclear run-on assays. Thus, CD13/APN expression by leukemic cells is regulated by interactions with the bone marrow microenvironment. CD13/APN expression in some ALL at diagnosis could result from a block in the signal transduction pathways that cause its suppression by bone marrow stromal cells.

Bone Marrow Cells↗
PubMed1994

A redox factor protein, ref1, is involved in negative gene regulation by extracellular calcium.

A rise in extracellular calcium (Ca2+e) suppresses not only secretion of parathyroid hormone (PTH) but also expression of the PTH gene to ensure constant plasma Ca2+ level. A nuclear protein(s) in a wide variety of cells bound to the specific DNA elements (negative Ca2+ responsive elements, nCaREs) in the human PTH gene in sequence-specific and Ca2+e concentration-dependent manners. Our Southwestern cloning revealed that a redox factor protein (ref1), which was known to activate several transcription factors via alterations of their redox state, belonged to an nCaRE binding protein. The level of ref1 mRNA as well as of its protein was elevated by an increase in Ca2+e concentration. In gel shift assay, anti-ref1 antibody eliminated formation of the nCaRE-protein complex. We also found that there was another protein(s) interacting with nCaREs and ref1. Further, experiments with an antisense-ref cDNA expression vector introduced into cultured cells suggested that DNA (nCaRE)-ref1 interaction led to Ca2+e-mediated transcriptional suppression. Thus, it is concluded that ref1 possesses transcription repressor activity in addition to its function as a transcriptional auxiliary protein.

Animals↗
PubMed1994

SCG10 mRNA localization in the hippocampus: comparison with other mRNAs encoding neuronal growth-associated proteins (nGAPs).

SCG10 is a nerve growth factor (NGF)-inducible, neuron-specific protein whose expression is tightly correlated with axonal and/or dendritic growth. We have recently shown that the mRNA encoding SCG10 is expressed at significant levels in certain subsets of neurons in the adult rat brain, while its expression is undetectable or negligible in other non-neuronal tissues. Here we show that regional SCG10 mRNA expression in the adult mouse brain is comparable to that in the rat, however, in the hippocampus its expression profile is distinct. In the mouse, SCG10 mRNA is expressed at high levels in pyramidal cells of CA3-CA4 sub-fields of Ammon's horn and at low levels in the CA1-CA2 sub-fields, while it is found rather uniformly throughout the pyramidal cell layer of the rat hippocampus. SCG10 mRNA is not detectable in the dentate gyrus of the mouse hippocampus, although it is expressed in the rat dentate gyrus. Comparison with other mRNAs encoding neuronal growth-associated proteins (nGAPs) such as GAP-43, MAP2, alpha 1-tubulin and stathmin suggests that dentate granule cells express a different repertoire of neuronal growth-associated genes in mouse and rat.

Animals↗
PubMed1994

Characteristics and partial purification of a novel cytosolic, magnesium-independent, neutral sphingomyelinase activated in the early signal transduction of 1 alpha,25-dihydroxyvitamin D3-induced HL-60 cell differentiation.

Treatment of HL-60 cells with a 1 alpha,25-dihydroxyvitamin D3 induces activation of a neutral sphingomyelinase (SMase), resulting in a decrease in sphingomyelin (SM) levels and an increase in ceramide levels in a proposed "sphingomyelin cycle" of cell regulation (Okazaki, T., Bell, R., and Hannun, Y. (1989) J. Biol. Chem. 264, 19076-19080). Cell-permeable synthetic ceramides induce HL-60 cell differentiation toward a monocytic lineage without conversion to sphingosine, suggesting that ceramide is a lipid mediator of cell differentiation (Okazaki, T., Bielawska, A., Bell, R., and Hannun, Y. (1990) J. Biol. Chem. 265, 15823-15831). In this study, we investigated a novel SMase that was activated 2-2.5 h after treatment of cells with 1 alpha,25-dihydroxyvitamin D3. The activated SMase was localized to the cytosolic fraction. It was inhibited by copper, ferric iron, and zinc and showed optimal activity at pH 7.5. A mixed micellar assay was developed for the enzyme, with optimal activity achieved at 12 mol% SM in Triton X-100 mixed micelles and at 20 mol% SM in deoxycholate micelles. The activity was modestly enhanced by phosphatidic acid, phosphatidylserine, or phosphatidylinositol, but not by other major phospholipids. Purification was performed by chromatography on DEAE anion-exchange, Q-Sepharose Fast Flow, hydroxylapatite, sphingosylphosphocholine affinity, and Superose 12 gel filtration columns. Two peaks of activity with molecular masses of 45 and 95 kDa were resolved by gel filtration chromatography on Superose 12. The specific activities of the purified 45- and 95-kDa enzymes were 2780 and 2790 nmol/mg/h, respectively. These data identify a novel cytosolic, magnesium-independent, neutral SMase(s) that is activated during cell differentiation.

Calcitriol↗
PubMed1994

CD4+ T cells require adhesion via LFA-1/ICAM-1 to induce target apoptosis in TNF-independent pathway.

An antigen-specific CD4+ T cell clone, OK2.21, and a hybridoma clone, A3.4C6, induced cytolysis and DNA fragmentation of appropriate targets in the presence of an anti-CD3 monoclonal antibody (Mab). In a double chamber system, OK2.21 killed TNF-sensitive targets that were separated from the T cells by a porous membrane. The killing was completely inhibited by anti-TNF antibody. On the other hand, neither OK2.21 nor A3.4C6 killed a TNF-insensitive target, A20.2J, that was separated from the T cells. Furthermore, the cytotoxicity and DNA fragmentation of A20.2J by anti-CD3 Mab-activated T cells were inhibited by both anti-LFA-1 and anti-ICAM-1 Mab. These results suggest that TNF is the only soluble cytolytic factor involved in CD4+ T cell-mediated cytotoxicity, and that TNF-independent apoptosis occurs through cell-to-cell contact via a LFA-1/ICAM-1 system.

Animals↗
PubMed1994

Abnormal distribution of nerve terminals in infantile hypertrophic pyloric stenosis.

Smooth muscle biopsy specimens obtained from nine infants with infantile hypertrophic pyloric stenosis (IHPS) and from three controls were studied immunohistochemically with respect to the distribution of nerve terminals and neurofilaments. To label nerve terminals and neurofilaments, monoclonal antibodies (MAb) 171B5 and 2F11 were used, respectively. In all specimens of the control group, nerve terminals were numerous in both the myenteric plexus and the muscle layer. There were abundant neurofilaments in the myenteric plexus and a moderate number in the muscle layer. In all specimens of the IHPS group, the density of nerve terminals and neurofilaments was reduced in the muscle layer. In the myenteric plexus, there was no such reduction. The results indicate poor neuronal innervation of the muscle layer in the pylorus of infants with IHPS. This poor innervation may be related to the pathogenesis of pyloric stenosis and hypertrophy.

Antibodies, Monoclonal↗
PubMed1994

High level expression of rat gamma-D-crystallin in Escherichia coli.

Gamma-crystallins have been implicated in various kinds of cataracts. In order to facilitate studies elucidating the molecular mechanism of cataractogenesis, large quantities of rat recombinant gamma-D-crystallin were produced in E coli. A full length cDNA clone coding for gamma-D-crystallin was isolated from a rat lens lambda gt11 cDNA library using a synthetic oligonucleotide as a probe. The coding region of this cDNA was inserted into a cloning vector pKK233-2 under the control of the trc promoter. The resulting construct, pKKCR91, was transfected into E coli to produce rat gamma-D-crystallin in an amount of 10-15% of the total bacterial proteins. The crystallin produced was purified to an apparent homogeneity as judged by SDS gel electrophoresis. The sequence of the N-terminal 11 amino acids of the purified crystallin was determined, showing that it is completely identical to that predicted from the cDNA sequence. Measurements of the far-UV CD spectra also revealed that recombinant rat gamma-D-crystallin thus produced retains a native conformational structure.

Amino Acid Sequence↗
PubMed1994

Differential localization of SCG10 and p19/stathmin messenger RNAs in adult rat brain indicates distinct roles for these growth-associated proteins.

SCG10 is a developmentally regulated, growth-associated protein (GAP) that was isolated as a neuronal marker of the neural crest. It was recently found that SCG10 shares an amino acid sequence similarity with a phosphoprotein named stathmin or p19 of which phosphorylation is induced by nerve growth factor and vasoactive intestinal peptide in PC12 cells and striatal neurons, respectively. While expression of SCG10 messenger RNA dramatically decreases during postnatal development, significant levels of expression still persist into adulthood. To examine possible roles of SCG10 in the adult brain, we examined the distribution of messenger RNAs encoding SCG10 and p19/stathmin as well as GAP-43 in adult rat brain sections by northern blot, RNase protection and in situ hybridization. SCG10 transcripts are found at high levels in long-distance projecting neurons and neurons with extensive dendritic arbors, while p19/stathmin messenger RNA was weakly distributed over most brain areas. Both messenger RNAs are expressed in neuronal subpopulations but not in glia, although the overall distribution of the transcripts of these two structurally related genes is distinct. The spatial and temporal expression profiles of SCG10 messenger RNA is comparable to that of GAP-43, another neuronal GAP, in the developing nervous system, however the expression of SCG10 messenger RNA in the adult brain is distinct from that of GAP-43, especially in the hippocampus and brain stem, where the dentate granule cells and sensory and motor neurons of brainstem express SCG10 but not GAP-43. These results suggest that SCG10 may have a unique role in the neuronal growth-response of subsets of mature neurons, and that SCG10 plays a stathmin-like function at nerve terminals, to which it may be rapidly transported by means of membrane attachment due to a hydrophobic domain present in SCG10 but not in p19/stathmin. This suggests that SCG10 may play a role in structural plasticity in the adult brain.

Animals↗
PubMed1994

Distribution of CENP-B boxes reflected in CREST centromere antigenic sites on long-range alpha-satellite DNA arrays of human chromosome 21.

The long-range organization of alphoid DNA arrays of human chromosome 21 was investigated using a mouse-human somatic cell hybrid. Two distinct long alphoid DNA arrays, the loci alpha 21-I and alpha 21-II, were identified in the centromere region of human chromosome 21. The alpha 21-I locus, composed of an array of 11 monomer repeat units (the 11 mer), was estimated to have a total length of 1.3 Mbp. CENP-B boxes, the binding sites of the centromere protein B (CENP-B), appeared in every other monomer unit in the 11 mer except for one place where two monomer units were repeated without any CENP-B box. The other locus, alpha 21-II, was found to be composed of alphoid subfamilies with low homology to the components of alpha 21-I locus. Five different alphoid clones presenting 32 monomer units in total were isolated from the alpha 21-II locus. Sequences of these monomer units diverged between 71-89% and no unit containing a CENP-B box was found. By analysis using two color FISH, the alpha 21-I was localized to the primary constriction, whereas the alpha 21-II site was located slightly to the short arm side. Furthermore, a combination of FISH and immunofluorescent staining indicated that the alpha 21-I site was co-localized and overlapped with the CREST centromere antigenic site on mitotic chromosomes and in interphase nuclei, while alpha 21-II was distributed broadly. Our data suggest that the locus alpha 21-I containing regularly spaced CENP-B boxes at high-frequency and the assembly site of the centromere antigens may be involved in common centromere function in both human and mouse cells.

Animals↗
PubMed1994

Molecular cloning and characterization of the rat cytochrome c oxidase subunit Vb gene.

We have isolated two non-overlapping clones containing the genes for subunit Vb of cytochrome c oxidase (COXVb) from a rat genomic library in Charon 4A using a newly isolated full-length cDNA as a probe. One of the two genomic clones, designated as lambda COXVb741, contained a functional gene (COXVb-1), while the other one, designated as lambda COXVb211, contained an intronless processed pseudogene (COXVb-2). The COXVb-1 gene spans approximately 1.8 kb and consists of four exons interrupted by three introns. The nucleotide sequences of all exons are completely identical to the corresponding sequences of the rat liver and brain COXVb cDNAs, indicating that this gene is actually expressed. The 5'-flanking region of the gene lacks conventional TATA and CAAT boxes, but exhibits strong promoter activity in the chloramphenicol acetyltransferase (CAT) assay. Deletional analysis and gel shift assay of the 5'-flanking region suggested that the binding of nuclear factor Sp-1 could be essential for transcription of the gene. Southern blotting analysis implied the occurrence of multiple COXVb genes in the rat genome. However, the results of the present experiments suggest that only the COXVb-1 gene is expressed in rat tissues.

Amino Acid Sequence↗
PubMed1994

Analysis of cytoplasmic and surface antigens in childhood T-cell acute lymphoblastic leukaemias: clinical relevance of cytoplasmic TCR beta chain expression.

Expression of surface and cytoplasmic antigens on the blasts from 42 cases of childhood T-cell acute lymphoblastic leukaemia (T-ALL) were analysed. All with childhood T-ALL, except for one case expressing cytoplasmic TCR delta chain, were classified on the basis of differential expression of cytoplasmic CD3 (cCD3), TCR beta chain (cTCR beta) and surface CD3 (sCD3) into the following three groups: group I (cCD3+, cTCR beta-, sCD3-), eight cases (19.5%); group II (cCD3+, cTCR beta +, sCD3-), 23 cases (56.1%); group III (cCD3+, cTCR beta +/-, sCD3+), 10 cases (24.4%). Each group defines the stepwise maturational stage of the CD3/TCR complex along the intrathymic T-cell differentiation. Group I had the lowest initial WBC count among the three groups (P < 0.05) and showed significantly (P < 0.05) a higher event-free survival (0.75) than those of group II (0.33). There was no significant difference in both the initial WBC count and the event-free survival between groups II and III. Thus, the absence of cTCR beta in sCD3-negative T-ALL appears to be a good prognostic factor, suggesting that this classification provides a useful tool to predict the prognosis of childhood T-ALL. This is the first report, to our knowledge, studying the relationship between the expression of cytoplasmic CD3/TCR antigens and the clinical features in T-ALL.

Adolescent↗
PubMed1994

A case of intractable diarrhea firmly suspected to have autoimmune enteropathy.

Protracted diarrhea with insulin dependent diabetes mellitus (DM) and hypothyroidism in a 9 month old Japanese girl who was firmly suspected to have autoimmune enteropathy (AIE) is reported. Her severe secretory diarrhea failed to respond to intensive antidiarrheic treatment and was gradually improved with steroid therapy. The circulating autoantibodies to enterocytes in her serum were detected by indirect immunofluorescence technique and the impaired suppressor T (Ts) cell function was proved by plaque forming assay using bead-separated CD4 or CD8 T cells together with CD19 B cells. The anti-enterocyte antibodies were exclusively of immunoglobulin M (IgM) class and were detected with the progress of the protracted diarrhea. Maximum antibody titer was obtained at the onset of DM and the disappearance of autoantibodies was associated with the resolution of the clinical symptoms and signs. The helper functions of adult CD4 T cells to induce Ig-secreting cells from adult and the patient were strikingly suppressed by adult CD8 T cells. However, the CD8 T cells from the patient lost the ability to inhibit the induction of these Ig-secreting cells when stimulated with adult CD4 T cells. Moreover, the patient's CD8 T cells stimulated rather than suppressed the induction of Ig-secreting cells from the patient when stimulated with the patient's CD4 T cells. These results suggest that the impaired Ts cell function in this patient might play some immunological role in the pathogenesis of AIE.

Autoantibodies↗