Biomedical subjects

A Okuda

Publications and source records attributed to A Okuda.

At least 37 records · Page 2Linked to original sources

PubMed1997

Constitutive endonuclease to induce high molecular weight or internucleosomal DNA fragmentation in freshly isolated leukemia cells.

Using an autodigestion method, we investigated endogenous endonuclease(s) in leukemia cells freshly obtained from pediatric patients with various types of leukemia. Endonucleolytic activity was found to cause both high molecular weight and internucleosomal DNA fragmentation at a neutral pH in whole cell lysates of all common acute lymphoblastic leukemia (cALL) blasts, which was Mg2+-dependent and Ca2+-independent. Whole lysates from most acute myeloblastic leukemia (AML) cells possessed similar endonuclease activity, but both Mg2+ and Ca2+ were required for the activity. Our results suggest that leukemia cells of different lineages have distinct constitutive endonucleases, which may play a role in the occurrence of apoptosis in these cells.

Apoptosis↗

PubMed1997

Myelodysplastic syndrome presenting as third malignancy after non-Hodgkin's lymphoma and osteosarcoma.

The patient was initially diagnosed as having non-Hodgkin's lymphoma and was cured following treatment with prednisolone, vincristine, daunorubicin, 1-asparaginase, and cyclophosphamide. Seven years and two months later, he developed osteosarcoma in his right femur. He received chemotherapy consisting of methotrexate, carboplatin, etoposide, and ifosfamide and again obtained remission. After 2 years and 7 months, however, he was found to have pancytopenia with morphological abnormalities in the erythroid and myeloid series. Diagnosis of myelodysplastic syndrome (MDS) was made. Cytogenetic analysis of bone marrow cells revealed -5 and -7, which is typical for secondary MDS. This is a rare case of third malignancy presumably caused by alkylating agents.

Adolescent↗

PubMed1997

Inhibition of superoxide production and chemotaxis by methotrexate in neutrophils primed by TNF-alpha or LPS.

We have demonstrated recently that methotrexate (MTX) inhibits superoxide generation and chemotaxis induced by N-formylmethionyl-leucyl-phenylalanine (fMLP) in neutrophils primed by granulocyte colony-stimulating factor (G-CSF). To extend these observations, we examined the in vitro effect of MTX on fMLP-stimulated superoxide generation and chemotaxis in neutrophils primed by either tumor necrosis factor alpha (TNF-alpha) or bacterial lipopolysaccharide (LPS). MTX inhibited superoxide generation and chemotaxis more efficiently in TNF-alpha- or LPS-primed neutrophils than in unprimed neutrophils. When either hypoxanthine or guanosine was added to the culture medium, the effects of MTX were partially counteracted. Furthermore, MTX caused a significant inhibition of both superoxide production induced by phorbol 12-myristate-13-acetate and chemotaxis induced by interleukin 8 in G-CSF-primed neutrophils. These results may support the hypothesis that neutrophils primed by different stimuli are more susceptible to the inhibitory effects of MTX on superoxide generation and chemotaxis irrespective of chemoattractants. Such an effect can be partly attributed to the perturbation of purine nucleotide biosynthesis.

Cells, Cultured↗

PubMed1996

An amino acid change in novel protein D123 is responsible for temperature-sensitive G1-phase arrest in a mutant of rat fibroblast line 3Y1.

A temperature-sensitive mutant of rat fibroblast line 3Y1, 3Y1tsD123, is arrested in the G1 phase of the cell cycle at restrictive temperature. Using a human cDNA expression library, we succeeded in the molecular cloning of a cDNA (designated as D123 cDNA) that functionally complemented the temperature-sensitive mutation. We then isolated rat D123 cDNA from a 3Y1 cDNA library using the human D123 cDNA probe. Both human and rat D123 cDNA contained a long open-reading-frame coding for a novel protein (designated as D123 protein) of 336 amino acids. A comparison of the nucleotide sequences of rat D123 cDNA and the corresponding cDNA of 3Y1tsD123-obtained by polymerase chain reaction in conjunction with reverse transcription showed that there was a difference in a single nucleotide that must cause a single amino acid change in D123 protein. Antibody raised against the recombinant protein of human D123 cDNA detected a 44-kDa D123 protein in human embryo lung fibroblasts and 3Y1. The level of D123 protein was much lower in 3Y1tsD123 than in 3Y1 at both permissive (33.8 degrees C) and restrictive (39.8 degrees C) temperatures. We suppose that quantitative and qualitative changes of D123 protein due to the amino acid change cause the temperature-sensitive arrest of 3Y1tsD123. On the other hand, the level of D123 protein in 3Y1 did not change significantly whether cells were proliferating or arrested at the saturation cell density. This indicates that the G1 arrest of 3Y1 at the saturation cell density does not involve the control of D123 protein level.

Amino Acid Sequence↗

PubMed1996

Normal mutation frequencies of somatic cells in patients receiving growth hormone therapy.

The number of reported cases of malignancy developing in growth hormone (GH) users worldwide has increased to more than 40. However, the causal relationship between GH administration and the occurrence of malignancies is still uncertain. We investigated somatic cell mutation frequencies (Mfs) or variant frequency (Vf) at three gene loci in patients with pituitary dwarfism receiving GH therapy to clarify the genetic effect of GH. Eighty-eight patients receiving GH therapy for at least 3 months and 42 age-matched healthy controls were studied. Mfs at hypoxanthineguanine phosphoribosyltransferase (HPRT) and T-cell receptor (TCR) loci in GH users were not significantly higher than in the controls. Although a few patients seemed to have a slightly increased Vf at the glycophorin A (GPA) locus, the difference was not statistically significant. In addition, there was no tendency for the Mfs (Vf) at these loci to increase with the duration of the GH therapy. These data seem to exclude the possibility that GH induces genetic instability in patients with pituitary dwarfism who are receiving GH therapy.

Adolescent↗

PubMed1996

Methotrexate inhibits superoxide production and chemotaxis in neutrophils activated by granulocyte colony-stimulating factor.

Treatment of circulating human neutrophils with recombinant human granulocyte colony-stimulating factor (rhG-CSF) for 30 min augmented superoxide generation and chemotaxis induced by N-formylmethionyl-leucyl-phenylalanine (fMLP) in a dose dependent manner. When neutrophils were treated with 1 microM of methotrexate (MTX) for 60 min after incubation with rhG-CSF (10 ng/ml), the effects of rhG-CSF on superoxide generation and chemotaxis were inhibited by approximately 49 and 29%, respectively. Although inhibitory effects of MTX were also seen in neutrophils not pretreated with rhG-CSF, the degree of inhibition was much less. The addition of either hypoxanthine or guanosine at a concentration of 100 microM to the culture medium significantly attenuated the effects of MTX. However, in neutrophils obtained from a patient with Lesch-Nyhan syndrome, which lacked hypoxanthine-guanine phosphoribosyl transferase activity neither hypoxanthine nor guanosine had any rescue effect. These results suggest that MTX inhibits superoxide generation and chemotaxis in rhG-CSF-activated neutrophils, at least in part, by disturbing purine nucleotide biosynthesis.

Cells, Cultured↗

PubMed1996

Effects of DNA ploidy patterns on the survival of patients with primary gastrointestinal lymphoma.

To assess the prognostic value of DNA ploidy patterns, the DNA ploidy patterns of 37 primary gastrointestinal lymphomas were determined by DNA flow cytometry, using paraffin-embedded archival specimens. The DNA ploidy patterns were diploid in 21 tumors and nondiploid in 16 tumors. Advanced clinical stage, as determined by the Ann Arbor Staging Classification, and nondiploid DNA ploidy patterns were associated with significantly reduced survival of the patients, whereas tumor size, tumor grade, and the S-phase fraction of tumor cells were not correlated with survival. A multivariate analysis disclosed that the variables which had significant prognostic value for primary gastrointestinal lymphoma were the clinical stage of the disease and the DNA ploidy patterns of the tumor cells.

DNA, Neoplasm↗

PubMed1996

Characteristics of transposon insertion mutants of mandelic acid-utilizing Pseudomonas putida strain A10L.

A soil isolate, Pseudomonas putida strain A10L that utilizes mandelate via the mandelate pathway was mutagenized by transposon Tn5-Mob insertion and mutant 168 lacking mandelate racemase (MR) and a mutant 254 lacking benzoylformate decarboxylase (BFDC) were obtained. Expression of (S)-mandelate dehydrogenase (MDH), BFDC, NAD(+)-dependent benzaldehyde dehydrogenase (BDH) and NADP(+)-dependent BDH in the MR-lacking mutant was not affected by the insertion, and it was inducible similarly to the wild type strain. On the other hand, expression of MR and MDH in the BFDC-lacking mutant was low and constitutive, and NAD(+)- and NADP(+)-dependent BDHs were produced at a rather high level under non-induced conditions by the mutant. Genes for MR (mdlA), MDH (mdlB), and BFDC (mdlC) were indicated to be organized in an operon in the order of mdlCBA. Optical resolution to obtain (R)-mandelate, a useful synthon for pharmaceuticals, was shown to be performed with the MR-lacking mutant.

Aldehyde Oxidoreductases↗

PubMed1996

The membranous bulge lingual to the mandibular molar tooth of a cat contains a small salivary gland.

The membranous bulge lingual to the mandibular molar tooth was examined microscopically in 12 cats and found to contain a small mixed salivary gland. Approximate size of the gland was 1.0-1.5 mm bucco-lingually, 3.0-3.5 mm mesio-distally and 3.0 mm of depth at the largest part. This gland is a tubuloacinar gland with multiple small openings through several short ducts to the surface of the lingual membrane. Mucous acini were predominant with a few serous demilunes.

Animals↗

PubMed1995

Selection and partial characterization of calcium ionophore (A23187) resistant cells.

We have selected calcium ionophore (A23187)-resistant cells (AR-7) in a human promyelocytic leukemia cell line, HL-60. AR-7 showed approximately 8.5-fold resistance to A23187 compared with the wild type cells after continuous exposure for 3 days. AR-7 had cross resistance to ionomycin (4.6-fold) and thapsigargin (340-fold) which can also increase intracellular Ca++. Similar magnitude of resistance to apoptosis, as defined by characteristic morphology and internucleosomal DNA fragmentation, induced by these agents was observed after 4 hr of incubation. However, both the elevation of intracellular Ca++ following stimulation with various concentrations of A23187 and the sensitivity to anti-cancer agents including etoposide, 1-beta-D arabinofuranosylcytosine, and hydroxyurea were comparable between the two cell types. This cell line is considered to be useful for exploring the mechanism(s) of cell death, especially apoptosis, induced by calcium ionophore.

Antineoplastic Agents↗

PubMed1995

Association of high molecular weight DNA fragmentation with apoptotic or non-apoptotic cell death induced by calcium ionophore.

Calcium ionophore (A23187)-induced high molecular weight (HMW) and internucleosomal DNA fragmentation were investigated in human leukemia cell lines. An apoptosis-sensitive cell line, HL-60, showed HMW, internucleosomal DNA fragmentation and morphological changes of apoptosis by A23187. MOLT-4, which is resistant to apoptosis, exhibited only HMW DNA fragmentation and died of necrosis under the same conditions. Autodigestion experiments suggested the endonucleolytic activity to cause HMW fragmentation in the cytoplasm of both cell lines. The activity was more dependent on Mg2+ than Ca2+ in HL-60, whereas it was Ca(2+)-dependent in MOLT-4. These results suggest that HMW DNA fragmentation is not specific to apoptosis.

Apoptosis↗

PubMed1995

Replication factor encoded by a putative oncogene, set, associated with myeloid leukemogenesis.

DNA replication of the adenovirus genome complexed with viral core proteins is dependent on the host factor designated template activating factor I (TAF-I) in addition to factors required for replication of the naked genome. Recently, we have purified TAF-I as 39- and 41-kDa polypeptides from HeLa cells. Here we describe the cloning of two human cDNAs encoding TAF-I. Nucleotide sequence analysis revealed that the 39-kDa polypeptide corresponds to the protein encoded by the set gene, which is the part of the putative oncogene associated with acute undifferentiated leukemia when translocated to the can gene. The 41-kDa protein contains the same amino acid sequence as the 39-kDa protein except that short N-terminal regions differ in both proteins. Recombinant proteins, which were purified from extracts of Escherichia coli, expressing the proteins from cloned cDNAs, possessed TAF-I activities in the in vitro replication assay. A particular feature of TAF-I proteins is the presence of a long acidic tail in the C-terminal region, which is thought to be an essential part of the SET-CAN fusion protein. Studies with mutant TAF-I proteins devoid of this acidic region indicated that the acidic region is essential for TAF-I activity.

Amino Acid Sequence↗

PubMed1995

Augmentation by aphidicolin of 1-beta-D-arabinofuranosylcytosine-induced c-jun and NF-kappa B activation in a human myeloid leukemia cell line: correlation with apoptosis.

1-beta-D-arabinofuranosylcytosine (ara-C) (2 microM) can induce apoptosis in a human myeloid leukemia cell line, U937, after 4 h of incubation. Pretreatment of cells with aphidicolin (2 microM) augments ara-C-induced apoptosis, since it was first observed at 0.4 microM ara-C and became more intense at 2 and 10 microM. Although aphidicolin itself had a marginal effect on c-jun expression, it significantly augmented ara-C induced c-jun upregulation by shortening the lag time and lowering ara-C concentrations necessary for the induction of detectable c-jun transcripts. Aphidicolin and ara-C acted synergistically to increase NF-kappa B DNA binding activity as determined by an electrophoretic mobility shift assay. Expression of c-myc was slightly increased through the DNA degradative phase, and was then downregulated. Thus, the activation of NF-kappa B and c-jun expression seems to be well correlated with the potentiation by aphidicolin of ara-C-induced apoptosis.

Antimetabolites, Antineoplastic↗

PubMed1995

Acute Budd-Chiari syndrome due to inferior vena cava occlusion following blunt trauma.

Inferior vena cava (IVC) thrombosis or obstruction is a complication rarely associated with blunt trauma. We present a case of IVC thrombo-occlusive lesion with both hepatic and renal failure which developed after a thoracoabdominal blunt trauma. Direct thrombectomy and patch cavoplasty were successfully carried out under deep hypothermia using cardiopulmonary bypass.

Acute Disease↗

PubMed1994

Pyrrolidine dithiocarbamate, a potent inhibitor of nuclear factor kappa B (NF-kappa B) activation, prevents apoptosis in human promyelocytic leukemia HL-60 cells and thymocytes.

We examined the effect of pyrrolidine dithiocarbamate (PDTC), which potently blocks the activation of nuclear factor kappa B (NF-kappa B), on the induction of apoptosis by a variety of agents. Treatment of a human promyelocytic leukemia cell line, HL-60, with 10 micrograms/mL etoposide or 2 microM 1-beta-D-arabinofuranosylcytosine induced NF-kappa B activation within 1 hr and subsequently caused apoptosis within 3-4 hr. The simultaneous addition of 50-500 microM PDTC with these agents blocked NF-kappa B activation and completely abrogated both morphologically apoptotic changes and internucleosomal DNA fragmentation for up to 6 hr. However, PDTC failed to inhibit the endonuclease activity contained in the whole cell lysates. The inhibitory effect of PDTC was also observed in etoposide- and dexamethasone-induced apoptosis in human thymocytes at a concentration of 1-10 microM. Since PDTC has both antioxidant and metal-ion chelating activities, we tested the effects of N-acetyl-L-cysteine (NAC) (antioxidant) or o-phenanthroline (OP) (metal-ion chelator) on the induction of apoptosis. Pretreatment of HL-60 cells or thymocytes with 100-500 microM OP for 2 hr, but not 10-60 mM NAC, suppressed subsequent occurrence of apoptosis induced by etoposide. These results suggest that the activation of NF-kappa B plays an important role in the apoptotic process of human hematopoietic cells.

Acetylcysteine↗

PubMed1994

Variable susceptibility to apoptosis induced by calcium ionophore in hybridomas between HL-60 promyelocytic and CEM T-lymphoblastic leukemia cell lines: relationship to constitutive Mg(2+)-dependent endonuclease.

We recently reported that treatment with calcium ionophore, A23187, induces apoptosis in human myelogenous leukemia cells but causes necrotic cell death in T-lymphoblastic leukemia cells. To better understand the underlying mechanisms of such different modes of cell death, we established hybridomas between HL-60 promyelocytic and CEM T-lymphoblastic leukemia cells. The resulting hybridomas were divided into three groups in terms of their susceptibility to apoptosis following exposure to A23187: (1) hybridomas highly sensitive to apoptosis, (2) hybridomas with intermediate sensitivity to apoptosis which occurs later and to a lesser extent, and (3) hybridomas resistant to apoptosis. However, growth inhibition after 72 h of incubation and an initial rise in intracellular free calcium concentrations induced by A23187 were similar in the three groups. Expression of Ca(2+)-independent/Mg(2+)-dependent endonuclease, which had an optimal pH of 7.5-8.5 and was inhibited by Zn2+, was correlated with the susceptibility of the hybridomas to A23187-induced apoptosis. Thus, this endonuclease may play, at least in part, an important role in the induction of apoptosis in leukemia cell lines. Analysis of hybridomas between apoptosis-sensitive and apoptosis-resistant cells is useful in the elucidation of genetic factors which regulate cell death.

Apoptosis↗

PubMed1994

Correlation of p53 with the clinicopathologic features and prognosis of colorectal adenocarcinoma.

Immunohistochemical staining of p53 was performed using an anti-p53 mouse monoclonal antibody, Pab1801, on 67 colorectal adenocarcinoma specimens to determine the prognostic value of p53 in colorectal cancer patients. Of a total of 67 tumors examined, p53 was detected in 34, but the rate of positive staining for p53 did not correlate with the clinical stage of disease. In 59 patients undergoing curative resection of the tumor, there was no significant difference in the recurrence rate (P = 0.137) or the disease-free survival rate between 28 patients with p53 positive tumors and 31 with p53 negative tumors (P = 0.135).

Adenocarcinoma↗

PubMed1994

Multichannel myocardial temperature probe.

We present a new system to measure myocardial temperature at multiple points in myocardium. This system consists of a probe with multiple thermocouples, a data collector, and a personal computer. We have demonstrated a change in distribution of temperature in myocardium during hypothermic cardioplegic arrest.

Bias↗