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Biomedical subjects

T Okazaki

Publications and source records attributed to T Okazaki.

At least 325 records · Page 18Linked to original sources
PubMed1989

[Conversion of acute leukemia from a T-lymphoid to a myeloid phenotype].

A 7-year-old girl with an acute leukemia was reported whose blasts showed conversion from a T-lymphoid to a myeloid phenotype. At the onset of the disease, the blasts were negative for peroxidase and displayed FAB L1 morphology. Surface marker analysis revealed only CD7 antigen. Although complete remission was achieved, an extramedullary relapse was identified as having a several subcutaneous tumors 15 months later. Tumor cells showed the same marker expression as that of the blasts at the onset. After short term culture without an addition of any differentiation stimulators, the blast cells expressed CD2, CD3, CD4, CD8, and CD25 antigens. The karyotype was 46, XX, t(12; 21) (p11; q22). The intensive chemotherapy and radiation therapy were carried out, however, a hematological relapse occurred 12 months later. At this time, the blasts were strongly positive for peroxidase and expressed HLA-DR and CD33 antigens with disappearance of the CD7 antigen. Chromosome analysis revealed the additional abnormalities (del (7) (p15), -17, +der (17) t (17;?) (p13;?].

Child↗
PubMed1989

[Monocytic crisis in chronic myeloid leukemia: a case report].

We report a 17-year-old female with chronic myeloid leukemia (CML) who developed monocytic crisis. She was diagnosed as chronic phase of Ph1-chromosome positive CML at 14 years old. Three years after the diagnosis of the disease, she was admitted to the hospital because of low grade fever, lethargy and marked splenomegaly. Small dose of Ara-C relieved her symptoms and splenomegaly. Six months later, however, a marked leukocytosis over 70,000/microliters were observed, and the peripheral blood smear disclosed that about 80% of the leukocytes were relatively mature monocytoid cells. Chromosomal analysis revealed additional abnormalities (double Ph1, +8, +9, +19). Lysozyme levels in serum and urine were high and NAP score was elevated. These monocytoid cells expressed receptors for IgG-Fc and C3, phagocytic activity, and monocytoid antigens which were determined by monoclonal antibodies (MY4, Mo2, OKM5). Cytochemically, almost all of monocytoid cells were positive for peroxidase and naphthol-ASD-chloroacetate esterase (CAE), but the monocytoid cells positive for non-specific esterase were limited. These data suggested that this case was monocytic crisis in CML with proliferation of CAE positive monocytoid cells. Among several types of blast crisis, monocytic crisis is extremely rare condition. The definite monocytic crisis demonstrated by this case may support the hypothesis that target cells of CML are pluripotent hematopoietic precursors.

Adolescent↗
PubMed1988

Construction and characterization of the deletion mutant of hupA and hupB genes in Escherichia coli.

Insertion and deletion mutations of the hupB and hupA genes, which encode the HU-1 and HU-2 proteins, respectively, of Escherichia coli, have been constructed in vitro and transferred to the hup loci on the bacterial chromosome. The mutations were constructed by inserting a gene encoding chloramphenicol resistance or kanamycin resistance into the coding region of the hupB or hupA gene, respectively. A complete deletion of the hupA gene was constructed by replacing the entire hupA coding region with the kanamycin resistance gene. Cells in which either the hupB or the hupA gene is defective grow normally, but cells in which both of the hup genes are defective exhibit phenotypes different from the wildtype strain. The hupA-hupB double mutants are cold-sensitive, although their growth rate is normal at 37 degrees C. Furthermore, the viability of the hupA-hupB double mutants is severely reduced when the cells are subjected to either cold shock or heat shock, indicating that the hup genes are essential for cell survival under some conditions of stress. The double mutants also exhibit filamentation when grown in the lower range of permissive growth temperature.

Alleles↗
PubMed1988

Production of a truncated human c-myc protein which binds to DNA.

Two kinds of truncated human c-myc proteins were produced in Escherichia coli. The human c-myc gene is composed of three exons, exons 2 and 3 having coding capacity for a protein of 439 amino acids. 252 N-terminal amino acids are encoded by exon 2, the C-terminal 187 amino acids being encoded by exon 3. One of the proteins (p42) produced in E. coli corresponds to 342 amino acids from the 98th Gln to the C-terminus, plus 21 amino acids derived from the H-ras gene at the N-terminus. The other (p23) corresponds to 155 amino acids from the 98th Gln to the 252nd Ser, plus five amino acids (Gly-Gly-Thr-Arg-Arg) at the C-terminus, plus 21 amino acids from the H-ras gene at the N-terminus. The p23 protein was produced by using cDNA in which a frame shift occurred at the boundary between exons 2 and 3. We investigated the DNA-binding activity in p42 and p23 proteins. DNA-cellulose column chromatography showed that p42 binds to DNA, whereas p23 does not. This DNA-binding activity of p42 was inhibited by antiserum prepared against p42 but not by antiserum against p23. This indicates that the DNA-binding activity of c-myc protein is localized in the portion encoded by exon 3.

Cloning, Molecular↗
PubMed1988

In vitro transcription of the origin region of replication of the Escherichia coli chromosome.

Transcription was carried out in vitro by RNA polymerase on supercoiled minichromosome DNA containing the replication origin of the Escherichia coli chromosome (oriC) and the products were analyzed. Leftward transcription starting from the 16-kDa gene promoter located adjacent to the right of oriC was inhibited by the DnaA protein, a protein essential for initiation of replication. This inhibition is due to binding of DnaA protein to the 9-base pair sequence (dnaA box) located just upstream of the 16-kDa gene promoter. The inhibition was observed at levels of DnaA protein and RNA polymerase comparable to those required for replication of oriC plasmids in vitro and was abolished at high levels of RNA polymerase. These results suggest that a balance of DnaA protein and RNA polymerase is important in regulating transcription and that this regulation operates under conditions that allow initiation of replication. The transcription traversed oriC with very few transcripts terminating before or within it. DnaA protein did not affect the chain length of these transcripts. Furthermore, we identified leftward transcripts which start close to position 177 in the oriC sequence.

Bacterial Proteins↗
PubMed1988

RNA-primed initiation sites of DNA replication in the origin region of bacteriophage lambda genome.

Using DNA molecules synthesized in the early stage of lambda phage infection, deoxynucleotides at the transition sites from primer RNA to DNA synthesis have been mapped in the 1.5 kbase area of the lambda phage genome containing the genetically defined replication origin (ori lambda). Sites in the 1-strand (the polarity of the 1-strand is 5' to 3' from the left to the right direction of the lambda phage genetic map) were distributed both inside and outside of the ori lambda, whereas the sites in the r-strand (the strand in the opposite polarity) were mainly distributed more than three hundred nucleotides apart from the ori lambda to the right. A CPuPu sequence was found at -12 to -10 region of transition sites of the r- and the 1-strands in the frequency of 80% and 70%, respectively, and over 60% of the CPuPu sequences were CAG. Properties of the transition sites are discussed in relation to the primer synthesis.

Bacteriophage lambda↗
PubMed1988

Molecular cloning and nucleotide sequence of the cDNA for human liver glutamate dehydrogenase precursor.

Two cDNA clones (lambda GDHh1 and lambda GDHn61) for glutamate dehydrogenase (GDH) were isolated from a human liver cDNA library in lambda gt11. The clone, lambda GDHh1, was isolated from the library using a synthetic 45mer oligodeoxy-ribonucleotide, the sequence of which was derived from the known amino acid sequence near the NH2-terminus of human liver GDH. Subsequently, lambda GDHn61 was isolated from the same library using lambda GDHh1 as a probe. The inserts of both clones contained an overlapping cDNA sequence for human liver GDH, consisting of a 5'-untranslated region of 70 bp, an open reading frame of 1677 bp, a 3'-untranslated region of 1262 bp and a 15 base poly(A) tract. The predicted amino acid sequence revealed that the human liver GDH precursor consisted of a total of 558 amino acid residues including the NH2-terminal presequence of 53 amino acids. The sequence deduced for the mature enzyme showed 94% homology to the previously reported amino acid sequence of human liver GDH.

Amino Acid Sequence↗
PubMed1988

5'-flanking region of the parathyroid hormone gene mediates negative regulation by 1,25-(OH)2 vitamin D3.

To study the effects of 1,25-(OH)2 vitamin D3 on the transcription of the human parathyroid hormone (PTH) gene, 684 base pairs of the 5'-flanking portion of the human PTH gene were fused to the bacterial neo gene. The fusion gene was transfected into rat pituitary cells, and mixed populations of colonies were selected using the neomycin analog, G418. The level of RNA initiated from the human PTH gene promoter region in these cells was suppressed by 1,25-(OH)2 vitamin D3. Synthesis of the same transcript under control of a viral promoter was not regulated by 1,25-(OH)2 vitamin D3. The effect of 1,25-(OH)2 vitamin D3 was detected within 24 h at physiologic doses of 1,25-(OH)2 vitamin D3, and was not influenced by addition of cycloheximide. Thus 1,25-(OH)2 vitamin D3 acts on the 5'-flanking portion of the PTH gene to decrease the rate of transcription by a mechanism that requires no new protein synthesis.

Animals↗
PubMed1988

An initiation site of DNA replication with transcriptional enhancer activity present upstream of the c-myc gene.

We have previously reported that c-myc protein may promote cellular DNA replication by binding to initiation sites of replication. Here we report that a putative origin of human cellular DNA replication (ori) is present at approximately 2 kb upstream of the coding region of the c-myc gene itself. The c-myc protein, or protein(s) complexed with c-myc protein, bind to the upstream region (approximately 200 bp in length) which has transcriptional enhancer activity as well as autonomously replicating activity in human cells, suggesting that the c-myc protein may be an enhancer binding protein as well as a DNA replication protein. Results with deletion mutants suggest that the sequence essential to the origin of DNA replication may be adjacent to, but cannot be clearly separated from, the sequence responsible for enhancer activity. Furthermore, when cloned DNA containing putative c-myc protein binding sequences was transfected as competitor into HL-60 cells, expression of c-myc was inhibited, suggesting that c-myc protein itself may be necessary for c-myc expression.

Base Sequence↗
PubMed1988

Evidence of intracellular and trans-acting differentiation-inducing activity in human promyelocytic leukemia HL-60 cells: its possible involvement in process of cell differentiation from a commitment step to a phenotype-expression step.

We previously reported that human promyelocytic leukemia HL-60 cells, when treated with various inducers in magnesium-deficient medium, became committed to differentiate but did not express the differentiation-related phenotypes (Okazaki et al., J. Cell. Physiol., 131:50-57, 1987). In the present study we demonstrated the existence of an intracellular differentiation-inducing activity (int-DIA) in differentiation-committed phenotype-nonexpressing HL-60 cells by using cybrid formation between untreated HL-60 cells and cytoplasts from HL-60 cells treated in magnesium-deficient medium with 100 nM 1 alpha,25-dihydroxyvitamin D3 (1,25(OH)2D3). Cell extracts from similarly treated HL-60 cells also showed int-DIA, which when added (10 mg total protein/ml) to culture of untreated HL-60 cells, could increase the percentages of nitroblue tetrazolium (NBT)- and nonspecific esterase (NSE)-positive cells from 1% to 53%, and from 0 to 32%, respectively. They also induced differentiation of human monoblastic leukemia U-937 cells and of human myeloblastic leukemia KG-1 cells but not of erythroleukemia K-562 cells. These results suggested that the int-DIA had a common effect on differentiation induction in several human myeloid cell lines and may be involved in inducing cells to proceed from a commitment to a phenotype-expression step during human myeloid cell differentiation.

Calcitriol↗
PubMed1988

Change in priming sites for discontinuous DNA synthesis between the monomeric and concatemeric stages of phage T7 replication.

We have analyzed the transition sites between primer RNA and DNA in a 589 bp segment of the bacteriophage T7 genome. In the monomeric replication stage, RNA-DNA transition sites are predominantly on the light (L) strand (with 5'----3' polarity on the genetic map) but rarely on the heavy (H) strand, indicating that replication proceeds semidiscontinuously with the H and L strands corresponding to the leading and lagging strands, respectively. The direction of replication is that expected from the position of the primary origin and also indicates that secondary origins are seldom if ever used. In the concatemeric stage of replication, RNA-DNA transition sites are instead distributed on both strands of the segment with equally high frequency, showing that initiation occurs within the concatemeric molecule per se and by a different mechanism.

Base Sequence↗
PubMed1988

Serum lactic dehydrogenase and its isoenzymes in patients with ovarian dysgerminoma.

Lactic dehydrogenase (LDH) is a glycolytic enzyme that may be elevated in the serum of patients with gonadal and extragonadal germinomas. In this report, a case of unilateral ovarian pure dysgerminoma with remarkably elevated levels of serum LDH is presented. After complete excision of the tumor, serum LDH levels promptly returned to normal levels. Although an electrophoretic pattern of serum LDH isoenzymes was within normal limits pre-operatively, an increase in LDH-1 and 2 was found 1 week after operation. Seventeen additional examples of ovarian dysgerminomas with elevated serum LDH levels have been reported in the English literature including five cases who had high levels of two fast fractions of LDH. These data suggest that serum LDH levels and its isoenzymes pattern are useful tumor markers for diagnosis and post-therapy surveillance in patients with ovarian dysgerminomas.

Adolescent↗
PubMed1988

Cloning of the mitochondrial genome of Rana catesbeiana and the nucleotide sequences of the ND2 and five tRNA genes.

The entire mitochondrial genome of Rana catesbeiana was cloned into a plasmid vector pBR322 at the unique BamHI site and the nucleotide sequences of the ND2 gene and of its flanking genes were determined. The ND2 gene was encoded by 1,033 base pairs and, as deduced from the nucleotide sequence, the ND2 product consisted of 344 amino acids with a molecular weight of 37,561. This gene was flanked on the 5' side by the tRNA genes for isoleucine, glutamine, and methionine and on the 3' side by those for tryptophan and alanine. These genes were the same in their organization as those found in the mammalian and Xenopus laevis mitochondrial genomes. A comparison of the putative amino acid sequences of the ND2 proteins of different animal species revealed that six regions in the sequence were well conserved during evolution, suggesting that some of these conserved sequences are crucial for biological activity of the ND2 protein. The nucleotide sequence homologies between the five tRNA genes of R. catesbeiana and their counterparts of mammals and X. laevis were in the range of 55 to 85%, depending on the tRNA and animal species.

Amino Acid Sequence↗
PubMed1988

Isolation and sequencing of a genomic clone encoding aspartic proteinase of Rhizopus niveus.

A gene encoding Rhizopus niveus aspartic proteinase was isolated from an R. niveus genomic library by using oligonucleotides probes corresponding to its partial amino acid sequence, and its nucleotide sequence was determined. By comparing its deduced amino acid sequence with the amino acid sequence of rhizopuspepsin (5, 26), we concluded that the R. niveus aspartic proteinase gene has an intron within its coding region and that it has a preproenzyme sequence of 66 amino acids upstream of the mature enzyme of 323 amino acids.

Amino Acid Sequence↗
PubMed1988

Staurosporine, a novel protein kinase inhibitor, enhances HL-60-cell differentiation induced by various compounds.

The effect of staurosporine, a novel calcium/phospholipid-dependent protein kinase (protein kinase C) inhibitor, on differentiation of human promyelocytic leukemic HL-60 cells, was investigated. Staurosporine inhibited HL-60-cell proliferation in a concentration-dependent manner, but did not induce HL-60-cell differentiation by itself. When staurosporine was added to HL-60 cells treated with a suboptimal concentration (1 nM) of 1 alpha,25 dihydroxyvitamin D3 (1,25(OH)2D3), cell differentiation was enhanced in a concentration-dependent manner and the percentages of nitro blue tetrazolium reducing ability and nonspecific esterase activity-positive cells increased from 6% to 51% and from 8% to 54%, respectively, on day 4 at a concentration of 5 nM. Staurosporine (5 nM) achieved almost the same enhancement effect in cultures treated with suboptimal concentrations of 1 nM all-trans-beta-retinoic acid (RA), 3 ng/ml actinomycin D (Act D), 100 microM dibutyryl cyclic adenosine 3':5'-monophosphate (dbc AMP), and 50 microM prostaglandin E1 (PG E1). These results suggest that the inhibition of protein kinase C activity by staurosporine exerts an important role in HL-60-cell differentiation induced by various compounds. Moreover, staurosporine (5 nM) completely inhibited optimal concentrations (50 nM) of [12-o-tetradecanoyl phorbol-13-acetate (TPA)]-induced cell differentiation, but enhanced optimal concentrations of dbc AMP (1 mM)-induced cell differentiation. On the other hand, 1-(5-isoquinolinyl-sulfonyl)-2-methylpiperazine, which has been reported to inhibit cyclic adenosine 3':5'-monophosphate-dependent protein kinase (protein kinase A) as much as protein kinase C, completely inhibited both cell differentiations induced by optimal concentrations of TPA (50 nM) and induced by optimal concentrations of dbc AMP (1 mM), and did not significantly enhance HL-60-cell differentiation induced by suboptimal concentrations of 1,25(OH)2D3, RA, and dbc AMP. Therefore, these results suggest that the inhibition of protein kinase C, which is not accompanied by that of protein kinase A, is concerned with the induction of HL-60-cell differentiation.

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