Biomedical subjects

T Ogura

Publications and source records attributed to T Ogura.

At least 19 recordsLinked to original sources

PubMed1992

The membrane properties and Ca-currents of the trigeminal root ganglion cells in primary culture of the marine catfish, Plotosus, studied with whole-cell recordings.

Neurons of the trigeminal root ganglion (TRG) were isolated from the marine catfish Plotosus. Collagenase treatment and culture in L15 medium, modified for higher tonicity, were required to remove their myelin sheath. TRG neurons were spherical 15-20 microns in diameter after 1-4 days culture, although they later developed extensive neurites. The membrane properties were studied by whole-cell recording technique. The resting potential was about -63 mV. The specific membrane resistance and capacitance, 5.9 K omega.cm2 and 1.2 microF/cm2, were similar to those of mouse dorsal root ganglion (DRG). The action potential, however, was usually humped, and followed by a long afterhyperpolarization. The maximum firing rate reached only about 70 Hz. Voltage-clamp study revealed TTX-sensitive Na current and TEA-sensitive K current, and in addition, two types of Ca currents: low- and high-voltage activated (LVA and HVA). The HVA current seemed to be involved in hump formation. The LVA current was similar in kinetics to T-type current of chick DRG, and was presumably inactivated at the resting potential, which might be removed during the afterhyperpolarization.

Action Potentials↗

PubMed1992

Involvement of DNA polymerase beta in proliferation of rat liver induced by lead nitrate or partial hepatectomy.

We have studied the expression pattern of DNA polymerase beta in two different models of in vivo cell proliferation. Both mRNA levels and enzyme activity of DNA polymerase beta markedly increased before and/or during DNA synthesis in proliferating hepatocytes in mitogen-treated and partially hepatectomized rats. The time-courses of the expression of the gene coding for DNA polymerase beta were significantly different in the two cell systems. A 5-fold increase in DNA polymerase beta mRNA was observed 8 h after lead nitrate administration, i.e. well before the onset of DNA synthesis. In the regenerative liver cells a 3-fold increase in the amount of mRNA was observed 24-48 h after partial hepatectomy, the event being coincident with extensive DNA synthesis. In both systems, the increase of mRNA levels was always paralleled by an increase in enzyme activity, suggesting that DNA polymerase beta activity may be regulated at a pre-translational level.

Animals↗

PubMed1992

Regulation of gene expression of proteasomes (multi-protease complexes) during growth and differentiation of human hematopoietic cells.

We have reported that proteasomes are expressed at abnormally high levels in various hematopoietic tumor cells (Kumatori, A., Tanaka, K., Inamura, N., Sone, S., Ogura, T., Matsumoto, T., Tachikawa, T., Shin, S., and Ichihara, A. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 7071-7075). In the present study, we examined changes in the expressions of proteasomes during growth of peripheral T-lymphocytes from healthy adults and differentiation of human leukemic cell lines. Up-regulation of mRNAs encoding multiple proteasome subunits was observed during proliferation of resting T-cells induced by mitogens such as phytohemagglutinin and interleukin-2. In contrast, in vitro terminal differentiation into monocytic, granulocytic, and erythroid cells of various immature leukemic cell lines, such as HL-60 promyelocytic leukemia cells and K562 erythroleukemia cells, by various inducing agents caused rapid and marked down-regulation of proteasomes expression, independently of the cell type, direction of differentiation, or type of signal. The syntheses of proteasome subunits of 21-31 kDa and their associated components of 35-110 kDa, measured by [35S]methionine incorporation, were much higher in mitogen-activated T-cells and unstimulated HL-60 cells, which grow rapidly, than in resting and differentiated cells, indicating apparent correlations of the mRNA levels of proteasomes with their translational activities. However, immunochemically, no detectable difference in the cellular contents of proteasomes was found in these cells in induced and uninduced states for proliferation and differentiation, suggesting accelerated turnover of proteasomes in rapidly proliferating cells. Inhibition of proteasome expression by an antisense oligodeoxynucleotide for the largest proteasome subunit, C2, caused partial arrest of cell cycle progression of T-lymphocytes, suggesting that up-regulation of proteasomes is indispensable for proliferation of the cells. We also observed that the nuclear fraction of proteasomes increased in proliferating T-cells and that proteasomes moved rapidly between the nucleus and cytoplasm during differentiation of HL-60 cells.

Base Sequence↗

PubMed1992

IL-4 up-regulates IL-1 receptor antagonist gene expression and its production in human blood monocytes.

IL-4 down-regulates the productions of IL-1 and TNF-alpha in human monocytes. We examined whether the productions of IL-1 and a specific receptor antagonist of IL-1 (IL-1Ra) in human blood monocytes were regulated differently. Highly purified blood monocytes, isolated by centrifugal elutriation from healthy donors, were stimulated with LPS in the presence or absence of IL-4, and their productions of IL-1 and IL-1Ra were measured by Northern blot and immunoblot analyses. IL-1 and IL-1Ra were produced by monocytes stimulated with LPS, but not with IL-4 alone. Marked up-regulation by IL-4 of IL-1Ra production in LPS-stimulated monocytes was observed at both the mRNA and protein levels. Maximal expressions of IL-1 beta and IL-1Ra mRNA in LPS-stimulated monocytes were observed 2 h and 8 h, respectively, after stimulation. The enhancement of IL-1Ra production by IL-4 was concluded to be due to enhanced gene transcription, because there was no difference in the half-lives of IL-1Ra mRNA in monocytes cultured with and without IL-4. Up-regulation of IL-1Ra production by IL-4 was also observed in monocytes stimulated with adherent IgG at both the mRNA and protein levels. This unique property of IL-4 may be important in down-regulation of the IL-1-initiated immune and/or inflammatory response, not only directly through inhibition of IL-1 production, but also indirectly through up-regulation of IL-1Ra production.

Gene Expression↗

PubMed1992

Observation of the FeIV=O stretching Raman band for a thiolate-ligated heme protein. Compound I of chloroperoxidase.

The FeIV=O stretching vibration has never been identified for a cysteine-coordinated heme enzyme. In this study, resonance Raman and visible absorption spectra were observed simultaneously for transient species in the catalytic reaction of chloroperoxidase with hydrogen peroxide by using our original apparatus for mixed-flow and Raman/absorption simultaneous measurements. For the first intermediate, the FeIV=O stretching Raman band was observed at 790 cm-1, which shifted to 756 cm-1 with the 18O derivative, but the v4 band was too weak to be identified. This suggested the formation of an oxoferryl porphyrin pi cation radical. The second intermediate gave an intense v4 band at 1,372 cm-1 but no oxygen isotope-sensitive Raman band, suggesting oxygen exchange with bulk water.

Chloride Peroxidase↗

PubMed1992

Establishment of human squamous carcinoma cell lines highly and minimally sensitive to bleomycin and analysis of factors involved in the sensitivity.

Human squamous carcinoma cell lines that were highly and minimally sensitive to bleomycin were established from clinical specimens and designated as SCCKN and SCCTF, respectively. Although these cell lines showed a similar growth doubling time in vitro, SCCTF was approximately ten times less sensitive to bleomycin than SCCKN. The bleomycin high and low sensitivities were stable even at the 70-cell passage level in vitro. In addition, nude mouse tumors produced by SCCTF were less sensitive to bleomycin that those produced by SCCKN, and the ratio of the mean tumor weight in bleomycin-treated mice to that in control mice was 89.2% in SCCTF and 18.8% in SCCKN. As compared with SCCKN, SCCTF also was less sensitive to peplomycin (5-fold), mitomycin C (2.3-fold), cis-diamine dichloroplatinum (2.5-fold), and vincristine (6.5-fold). Analyses of low bleomycin sensitivity showed that SCCTF had an approximately 20% decreased cellular accumulation and retention of bleomycin, 1.2-fold increase of bleomycin hydrolase activity, elevated DNA repair activity, and increased poly(adenosine diphosphate-ribose) polymerase activity as compared with SCCKN.

Animals↗

PubMed1992

E.coli MukB protein involved in chromosome partition forms a homodimer with a rod-and-hinge structure having DNA binding and ATP/GTP binding activities.

mukB mutants of Escherichia coli are defective in the correct partitioning of replicated chromosomes. This results in the appearance of normal-sized anucleate (chromosome-less) cells during cell proliferation. Based on the nucleotide sequence of the mukB gene, the MukB protein of 177 kDa was predicted to be a filamentous protein with globular domains at the ends, and also having DNA binding and nucleotide binding abilities. Here we present evidence that the purified MukB protein possesses these characteristics. MukB forms a homodimer with a rod-and-hinge structure having a pair of large, C-terminal globular domains at one end and a pair of small, N-terminal globular domains at the opposite end; it tends to bend at a middle hinge site of the rod section. Chromatography in a DNA-cellulose column and the gel retardation assay revealed that MukB possesses DNA binding activity. Photoaffinity cross-linking experiments showed that MukB binds to ATP and GTP in the presence of Zn2+. Throughout the purification steps, acyl carrier protein was co-purified with MukB.

Acyl Carrier Protein↗

PubMed1992

Differential effects of interleukin-4 on superoxide anion production by human alveolar macrophages stimulated with lipopolysaccharide and interferon-gamma.

The effect of interleukin-4 (IL-4) on the activation state of human alveolar macrophages (AMs) and blood monocytes induced by lipopolysaccharide (LPS) or recombinant interferon-gamma (IFN-gamma) was investigated on the basis of their ability to produce superoxide anion (O2-). AMs were obtained from healthy donors by bronchoalveolar lavage, and O2- productions of these cells were assayed by a cytochrome c reduction method after incubation with stimulants for 24 h. AMs produced more O2- than autologous blood monocytes when stimulated with LPS. IL-4 alone had little effect on O2- production by unstimulated AMs but down-regulated O2- production by LPS-stimulated AMs in a dose-dependent manner. IL-4 also suppressed O2- production by AMs induced by the synergistic actions of muramyl dipeptide (norMDP) and IFN-gamma. Maximum suppression by IL-4 of O2- production by AMs was observed when IL-4 was added within 1 h after initiation of LPS stimulation. AMs also showed high O2- production when stimulated with IFN-gamma alone. In contrast to its suppression of O2- production by LPS-stimulated AMs, IL-4 enhanced O2- production by AMs stimulated with IFN-gamma. These data suggest that IL-4 is an important regulator of O2- production by macrophages through different pathways depending on the stimulus.

Adult↗

PubMed1992

Participation of poly(ADP-ribose) polymerase in the drug sensitivity in human lung cancer cell lines.

Poly(ADP-ribose) polymerase has been generally assumed to be involved in DNA repair. The level of the enzyme in various lung cancer cell lines was examined to determine if it is involved in drug resistance. Among nine cell lines of lung cancer tested, small-cell lung cancer lines, which showed higher sensitivity to cisplatin and etoposide, were unexpectedly found to contain significantly higher poly(ADP-ribose) polymerase activity than five non-small-cell lung cancer cell lines. This activity inversely correlated with IC50 values of lung cancer cell lines to etoposide, an inhibitor of topoisomerase II. The polymerase activity was also examined in several cisplatin-resistant variants of the cell lines. However, no difference was observed between parental and cisplatin-resistant cells. There was no significant relation between poly(ADP-ribose) polymerase activity and IC50 values for cisplatin and carboplatin. Although this enzyme was considered to play some role in the resistance to specific drugs, it might not be a critical factor in cisplatin-induced cytotoxicity.

Antineoplastic Agents↗

PubMed1992

Human blood monocyte activation by Nocardia rubra cell wall skeleton for productions of interleukin 1 and tumor necrosis factor-alpha.

Human blood monocytes were obtained from peripheral blood of healthy donors by counter-flow centrifugal elutriation. Functional integrity of monocytes for production of interleukin 1 (IL-1) and tumor necrosis factor alpha (TNF-alpha) in response to Nocardia rubra cell wall skeleton (N-CWS) was examined by bioassay and enzyme immunoassay. Monocytes treated with N-CWS at more than 0.5 microgram/ml produced IL-1 and TNF-alpha extracellularly. Extracellular TNF activity appeared within 4 h, and maximally, 16 h after N-CWS stimulation, whereas longer time was needed for IL-1 activity to appear, the peak production being at 24 h. The neutralizing experiment also showed that anti TNF-alpha antibody did not affect IL-1 production by the monocytes treated with N-CWS, suggesting independency of IL-1 production of TNF-alpha. These results suggest that the therapeutic antitumor effect of N-CWS is due, in part at least, to the augmented production of these monokines.

Bacterial Proteins↗

PubMed1992

Prevention of malodor from intraoral gauze tamponade with the topical use of clindamycin.

Azulene ointment with a small dose of clindamycin was used topically in eight patients with maxillary cancer with the intent to inhibit the malodor that originates from a gauze tamponade applied to the postoperative maxillary bony defect. The malodor was either markedly decreased or eliminated in all cases. Concurrent with the decrease or elimination of the malodor, anaerobic microorganisms such as Bacteroides and Peptostreptococcus, which are considered to be involved in the generation of malodor, also became undetectable.

Administration, Topical↗

PubMed1992

Characterization of high molecular weights of complexes and polymers of cytoplasmic proteins in Escherichia coli.

To search for filamentous polymers of cytoplasmic proteins of Escherichia coli, high molecular weights (> 670 kDa) of protein complexes of cell extracts were fractionated by gel filtration and ion-exchange column chromatography. Proteins of 100, 77 and 52 kDa were co-purified. The 100- and 52-kDa proteins were identified to be pyruvate dehydrogenase and lipoamide dehydrogenase, respectively, by determining the N-terminal amino acid sequences. Experimental results indicate that the 77-kDa protein is identical to dihydrolipoamide acyltransferase. The 100-kDa protein was found to be identical to the 100-kDa protein described by Tomioka (1991), and was related to the formation of filaments and sheets in the presence of 100 mM KCl. However, neither long filaments nor sheets were observed in our sample containing these enzymes, which was not consistent with Tomioka's conclusion. Another 100-kDa protein which forms spirosome-like particles was purified and identified to be alcohol dehydrogenase based on the N-terminal sequence.

Acyltransferases↗

PubMed1992

Effector cell analysis of human multidrug-resistant cell killing by mouse-human chimeric antibody against P-glycoprotein.

A mouse-human chimeric monoclonal antibody (mAb), MH162, against P-glycoprotein was previously found to be more effective than an all-mouse mAb (MRK16) in lysis of multidrug-resistant (MDR) tumor cells by blood mononuclear cells. The present study was performed to identify the effector cells responsible for the chimeric mAb-dependent cell-mediated cytotoxicity (ADCC) against MDR cells. The ADCC reaction was assessed by a 6-h 51Cr release assay. Highly purified lymphocytes (greater than 99%), monocytes (greater than 99%) and neutrophils (greater than 96%) were obtained from peripheral blood of the same healthy donors. A comparison of these three effector cell populations showed no difference between MH162 and its all-murine counterpart MRK16 in MDR cell lysis by monocytes or neutrophils. But MH162 was more effective than MRK16 in lymphocyte-mediated lysis of the MDR cells. The lymphocytes responsible for this ADCC had CD16+ Fc receptors. Pretreatment of monocytes with colony-stimulating factors (IL-3, GM-CSF and M-CSF) caused significant increase in their MH162-mediated lysis of MDR cells. Another anti-P-glycoprotein chimeric mAb (MH171) was also more effective than its murine counterpart MRK17 in lymphocyte-mediated lysis of MDR cells. These findings suggest that mouse-human chimeric mAbs may be useful therapeutically for in vivo destruction of MDR cancer cells by the ADCC reaction.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1992

Granulocyte-colony-stimulating factor enhances the circulating hematopoietic progenitors in lung cancer patients treated with cisplatin-containing regimens.

A phase II study examining the effects of human recombinant granulocyte-colony-stimulating factor (G-CSF) on the growth of colony-forming unit-granulocyte macrophage (CFU-GM) in the bone marrow and in the peripheral blood was performed in lung cancer patients treated with cisplatin-containing regimens. Treatment with G-CSF following chemotherapy significantly increased the absolute granulocyte count. No significant effect of G-CSF on either the platelet or the red blood cell count was observed. Treatment with G-CSF did not affect the CFU-GM levels in the bone marrow, but did have a significant effect on peripheral blood CFU-GM levels 14 days after initiation of chemotherapy (P less than 0.05). Four patients demonstrated a rebound increase in the level of peripheral blood CFU-GM during the first course of chemotherapy without G-CSF. In contrast, eight patients displayed increase in peripheral blood CFU-GM levels during the second course of chemotherapy with G-CSF treatment. These findings demonstrate that G-CSF is a potent stimulator of granulocyte proliferation as well as a potent agent for promoting transport of hematopoietic progenitors from the bone marrow into the peripheral blood.

Aged↗

PubMed1992

Inhibition by fibrin coagulation of lung cancer cell destruction by human interleukin-2-activated killer cells.

We examined the effect of fibrin coagulation on tumor cytotoxicity mediated by human lymphokine (IL-2)-activated killer (LAK) cells. LAK cells were induced from peripheral blood mononuclear cells (MNC) by culture with recombinant IL-2 for 4 or 5 days, and LAK cell-mediated cytotoxicity against tumor cells was assessed by 51Cr release assay in the presence or absence of plasma from normal subjects and lung cancer patients. Plasma did not affect the phase of induction of LAK activity by IL-2, but dose-dependently inhibited the effector phase of LAK cell-mediated cytotoxicity against Daudi cells. Similar inhibition of LAK cell-mediated cytotoxicity was observed on pretreatment of Daudi cells and human lung cancer cell lines with human fibrinogen plus thrombin. A parallel relationship was found between the amount of fibrinogen in plasma of lung cancer patients and inhibition of LAK cytotoxicity. This inhibition was reduced by addition of anticoagulants (heparin or argatroban). These findings suggest that fibrin coagulation on tumor cells protects them from LAK cell-mediated tumor cytotoxicity in malignant lesions and that a combination of an anticoagulant drug and IL-2/LAK therapy may be effective for treatment of lung cancer patients.

Aged↗

PubMed1992

Enhancement by monocytes of perforin production and its gene expression by human CD8+ T cells stimulated with interleukin-2.

Pore-forming protein (PFP) is an important effector molecule for cytotoxicity mediated by cytotoxic T cells and NK cells. In the present study, the effect of monocytes on PFP production by interleukin-2 (IL-2)-stimulated T lymphocytes was examined. Highly purified lymphocytes (> 99%) and monocytes (> 90%) were isolated by centrifugal elutriation from peripheral blood of healthy donors, and, CD4+ and CD8+ cells were isolated from the purified lymphocytes by using antibody-bound magnetic beads. PFP production was quantitated with a universal microspectrophotometer in combination with immunostaining using anti-PFP antibody. Monocytes did not produce any PFP. High levels of PFP production were observed in CD8+ cells, but not CD4+ cells after incubation for 4 days with IL-2. Addition of monocytes to cultures of CD8+ cells resulted in significant augmentation of PFP production after 3 days' stimulation with IL-2. Monokines (TNF alpha and IL-6) caused a significant increase in PFP production by IL-2-stimulated CD8+ cells. Northern blot analysis revealed that the PFP mRNA levels was enhanced by stimulation with IL-2, and that addition of monocytes to cultures of CD8+ cells plus IL-2 augmented their PFP mRNA expression. These observations suggest that monocytes are important in in situ regulation of the CD8+ T cell-mediated cytotoxic response through production of PFP.

Adult↗

PubMed1992

IL-6 in malignant pleural effusions and its augmentation by intrapleural instillation of IL-2.

The levels and activities of endogenous IL-6 in malignant pleural effusions due to lung cancer before and during daily intrapleural instillations of recombinant IL-2 were examined by enzyme immunoassay and bioassay using an IL-6-dependent murine hybridoma cell line MH60.BSF2. Before therapy, malignant pleural effusions contained various levels of IL-6. Daily intrapleural instillation of recombinant IL-2 for treatment of malignant pleurisy resulted in significant augmentation of the levels and activities of IL-6 in the pleural effusions. On fractionation of the pleural effusion by chromatography, one major peak of material with a mol. wt of 24 kD showed IL-6 activity. In contrast, no significant level of tumour necrosis factor-alpha or IL-1 beta was detectable in pleural effusions before or during local IL-2 therapy. These data suggest that IL-2 is an important regulatory factor of secondary IL-6 production.

Adenocarcinoma↗

PubMed1992

Serum dipeptidyl peptidase (DPP) IV activity in hamster buccal pouch carcinogenesis with 9,10-dimethyl-1,2-benzanthracene.

Dynamic change of serum DPP IV activity in carcinogenesis of hamster buccal pouch epithelium with DMBA was investigated. The serum enzyme level in hamster (21.5 +/- 3.1 IU/l serum) was decreased gradually from the 8th to the 10th wk when papillomas were induced by DMBA application (18.9 +/- 2.7 IU/l serum). The enzyme level was further decreased in the formation of carcinoma in situ or early invasive carcinoma (13.2 +/- 0.5 IU/l serum), and reached to less than half of the normal level at the time when tumors were diagnosed as squamous cell carcinoma histologically (8.1 +/- 1.3 IU/l serum). This enzyme level was increased by tumor excision and decreased again by tumor recurrence toward death. These findings suggested that the decrease of serum DPP IV activity occurred from the early stage of hamster buccal pouch carcinogenesis as a tumor-burden marker.

9,10-Dimethyl-1,2-benzanthracene↗