Biomedical subjects

J Nishimura

Publications and source records attributed to J Nishimura.

At least 19 recordsLinked to original sources

PubMed1992

Platelet derived growth factor induces c-fos and c-myc mRNA in rat aortic smooth muscle cells in primary culture without elevation of intracellular Ca2+ concentration.

Platelet derived growth factor (PDGF) has been shown to induce c-fos and c-myc proto-oncogenes. In the present study, we investigated the effects of genistein, a tyrosine kinase inhibitor, and NiCl2, a Ca2+ influx blocker, on PDGF-induced Ca2+ transient and on expression of c-fos and c-myc mRNA. In the presence of extracellular Ca2+, PDGF induced elevation of intracellular Ca2+ concentration ([Ca2+]i) and increases in c-fos and c-myc mRNA, as detected by reverse transcription polymerase chain reaction (RT-PCR) and Northern hybridization. PDGF-induced [Ca2+]i elevation was composed of an initial transient increase (first component) followed by steady state elevation (second component). Genistein (10 microM) blocked the 1st, but not the 2nd, component of [Ca2+]i elevation induced by PDGF. NiCl2 (1 mM) and removal of extracellular Ca2+ inhibited the 2nd, but not the 1st, component. In the presence of 10 microM genistein and 1 mM NiCl2, PDGF induced c-fos and c-myc mRNA, although the [Ca2+]i elevation could be completely blocked by these two agents. These results indicate that elevation of [Ca2+]i is not a prerequisite condition for PDGF to induce c-fos and/or c-myc mRNA in rat aortic smooth muscle cells in primary culture.

Animals↗

PubMed1992

cAMP induces up-regulation of ETA receptor mRNA and increases responsiveness to endothelin-1 of rat aortic smooth muscle cells in primary culture.

The effects of cAMP on the expression of ETA (ET-1 selective type) receptor mRNA and on the response to endothelin-1 (ET-1) were investigated in rat aortic smooth muscle cells in primary culture, using reverse transcription polymerase chain reaction (RT-PCR) and fura-2 microfluorometry of cytosolic Ca2+ concentrations ([Ca2+]i). Incubation of the smooth muscle cells with 10 microM forskolin and 10 microM 3-isobutyl-1-methyl-xanthine (IBMX) induced an increase in ETA receptor mRNA by 420% of control after 24 hours. ET-1 induced a biphasic increase in [Ca2+]i, first transient and second sustained phases. Incubation of the smooth muscle cells with forskolin and IBMX for 24 hours increased the [Ca2+]i response by 849% in the first phase and 286% in the second phase, compared with time-matched controls. From these results, we conclude that cAMP induces an up-regulation of the ETA receptor mRNA and increases responsiveness to ET-1 of rat aortic smooth muscle cells in primary culture.

1-Methyl-3-isobutylxanthine↗

PubMed1992

Modulation of expression of multidrug resistance gene (mdr-1) by adriamycin.

The acquired resistance to various drugs in cancer is mediated by P-glycoprotein (P-gp) which is encoded by the mdr-1 gene. An increased level of mdr-1/P-gp was demonstrated after chemotherapy administered to treat cancer in humans. To clarify the direct effect of anticancer drugs on mdr-1/P-gp expression, we investigated the change in transport of adriamycin (ADR), and the expression of the mdr-1 gene and P-gp in an ADR-treated, multidrug-resistant leukemic cell line (K562/ADR500). The addition of ADR induced the over-expression of mdr-1/P-gp, which led to a transient decrease in the intracellular accumulation of ADR although the difference was not statistically significant. A maximal effect was observed after 4 h incubation, returning to the baseline level after further incubation for 12-24 h. The phosphorylation of P-gp was inversely correlated with the levels of P-gp. These observations suggest that ADR itself modulates both the expression and function of P-gp. Determination of the optimal schedule for administering adriamycin is essential to achieving the optimal effect in treating cancer.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1992

Endothelin-1 inhibits and enhances contraction of porcine coronary arterial strips with an intact endothelium.

Using front-surface fluorometry and fura-2-loaded porcine coronary arterial strips with an intact endothelium, changes in cytosolic Ca2+ concentrations ([Ca2+]i) and tension of smooth muscle were simultaneously monitored in an attempt to determine the vasoactive properties of endothelin-1 (ET-1). ET-1 in low concentrations (0.1-1nM) caused a significant transient decrease in [Ca2+]i and tension of the strips precontracted with 10(-7) M U-46619. The maximal decreases in [Ca2+]i and tension were obtained with 0.6nM ET-1. In higher concentrations (1nM-100nM), there was no reduction in [Ca2+]i or tension; the contraction induced by U-46619 was potentiated. The decreases in [Ca2+]i and tension induced by ET-1 were inhibited by the mechanical removal of the endothelium or by pretreatment with NG-nitro-L-arginine and were slightly attenuated by indomethacin. Thus, ET-1 in low concentrations can induce endothelium-dependent transient relaxations accompanied by transient reductions of [Ca2+]i in isolated porcine coronary arteries. This effect is mainly mediated by the release of endothelium-derived relaxing factor.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMed1992

Regulation of transferrin receptors by iron in human erythroblasts.

We investigated the regulatory mechanism of human erythroblast transferrin receptors (Tf.R) under conditions of iron deprivation and iron loading. Treatment of erythroblasts with an iron chelator, desferrioxamine, induced an increase in surface Tf.R number associated with an elevation of biosynthetic rate and the mRNA level of Tf.R. Reduced cellular iron pool increased the Tf.R number by altering the level of mRNA, as in nonhemoglobin-producing cells. Although treatment of erythroblasts with hemin induced a decrease in the biosynthetic rate and in the level of mRNA, the number of surface Tf.R did not decrease. This phenomenon may explain the fact that a high level of serum iron has no influence on the surface Tf.R number in vivo, as we reported previously. We suggest the existence of a regulatory mechanism specific for hemoglobin-producing cells that keeps surface Tf.R expression constant despite iron loading.

Blotting, Northern↗

PubMed1992

A case of combined primary biliary cirrhosis, ulcerative colitis and chronic myelocytic leukemia.

A rare case of primary biliary cirrhosis, ulcerative colitis and chronic myelocytic leukemia is described in a 49-year-old Japanese diabetic woman. Primary biliary cirrhosis was diagnosed by characteristic liver histology and positive serum mitochondrial antibody test. Ulcerative colitis was diagnosed by typical findings of barium enema and colonoscopy, negative fecal test for pathogens and compatible rectal histology. Chronic myelocytic leukemia was determined by representative hematologic findings and positive result for Ph1 chromosome. This is the first case with combination of primary biliary cirrhosis, ulcerative colitis and chronic myelocytic leukemia.

Colitis, Ulcerative↗

PubMed1992

Analysis of clonality at the level of progenitors in chronic myelogenous leukaemia using the polymerase chain reaction.

The Philadelphia (Ph1) chromosome is a specific structural abnormality in which the abl oncogene is activated due to the formation of the novel chimeric gene, bcr/abl. To investigate the clinicopathological role of bcr/abl in Ph1-positive chronic myelogenous leukaemia (CML), we studied the clonal origin of haematopoietic progenitors by detecting bcr/abl mRNA in a single haematopoietic colony using the polymerase chain reaction (PCR). Nine patients with CML were examined. In 5 chronic phase patients, all granulocyte/macrophage (CFU-GM) and erythroid (BFU-E) progenitor-derived colonies were positive for bcr/abl mRNA. Colonies in which the transcripts were not detectable were observed in 4 patients. These 4 patients included one patient with a normal karyotype and without splenomegaly, a patient with cyclic oscillation of her white blood cell level, a patient treated with busulfan and interferon-alpha (INF-alpha), and a patient relapsing after allogenic bone marrow transplantation (BMT). Our observations indicate that detection of Ph1-positive clones by PCR may be used to evaluate clinical stages and the effects of treatment in CML.

Adolescent↗

PubMed1992

Deletion of chromosome 6q in two cases of acute myeloblastic leukemia and a review of the literature.

Two cases of acute myeloblastic leukemia (AML M2) associated with a deletion of chromosome 6q are described. One was a 38-year-old man with constitutional inversion of chromosome 9, and another was a 57-year-old female atomic-bomb survivor. The karyotype of these patients were 46,XY,del(6)(q12q14),inv(9)(p11q13), and 47,XX,6q-,+min, respectively. In both cases c-myb protooncogene, which is located in chromosome 6q, was neither deleted nor rearranged, and c-myb messenger RNA level was not elevated. These results suggest that c-myb is not involved in the leukemogenesis of AML with 6q- as well as lymphoid malignancies with 6q-. Out of 23 AML cases with 6q- reviewed, 6 cases had erythroleukemia, and 4 developed in Down syndrome patients.

Adult↗

PubMed1992

Deficient surface expression of glycosylphosphatidylinositol-anchored proteins in B cell lines established from patients with paroxysmal nocturnal hemoglobinuria.

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired type hemolytic disorder. Hematopoietic cells of patients with PNH are deficient in glycosylphosphatidylinositol (GPI) anchored membrane proteins. Since some membrane-bound complement inhibitors, such as CD59 and decay accelerating factor (DAF), are GPI anchored proteins, abnormal cells from patients with PNH are sensitive to complement attack. Their myeloid and erythroid cells are affected more than their lymphoid cells. Patients whose B cells were severely deficient in GPI anchored proteins were chosen to establish cell lines by Epstein-Barr virus mediated transformation. The lines established (SS-1-, TK-1-, and TK-14- cell lines) had the following characteristics of PNH. First, GPI anchored proteins were completely absent from the surface of SS-1- and TK-14- cells, and were expressed at very low levels on TK-1- cells, whereas polypeptide anchored proteins were normally expressed on these three lines. Secondly, DAF mRNAs of the SS-1- cell line were qualitatively and quantitatively indistinguishable from those of a control, wild-type cell line. Third, pro-CD59 and pro-DAF molecules were detected intracellularly in these cell lines, their pro-CD59 being smaller and more hydrophilic than that from a wild-type cell line. These cell lines should be useful in further studies on the pathogenesis of PNH.

Antigens, CD↗

PubMed1992

Noradrenergic excitatory inputs to median preoptic neurones in rats.

Extracellular single-unit activity was recorded from 21 median preoptic nucleus (MnPO) neurones, antidromically identified as projecting to the hypothalamic paraventricular nucleus (PVN), in urethane-anaesthetized male rats. Of these identified MnPO neurones, 14 displayed an excitatory response in neuronal excitability following electrical stimulation (5 Hz, 600 microA) of the A1 noradrenergic region of the ventrolateral medulla, while the remaining neurones were unresponsive. The excitatory response of MnPO neurones was blocked by microiontophoretically applied phentolamine, an alpha-adrenoceptor antagonist, but not by timolol, a beta-adrenoceptor antagonist. These results suggest that the A1 region acts to enhance the activity of MnPO neurones projecting to the PVN via an alpha-adrenoceptor mechanism.

Adrenergic alpha-Antagonists↗

PubMed1992

Transient myosin phosphorylation at constant Ca2+ during agonist activation of permeabilized arteries.

Norepinephrine (NE) plus guanosine triphosphate (GTP) increases myofilament Ca2+ sensitivity in alpha-toxin-permeabilized smooth muscle. We used alpha-toxin-permeabilized rabbit mesenteric arteries to determine the temporal relationships among force, myosin light chain (MLC) phosphorylation, stiffness, and shortening velocity during contractions in response to Ca2+ alone and to the same [Ca2+] in the presence of NE plus GTP. The addition of NE plus GTP caused a marked increase in the tonic contraction but only transiently elevated the level of MLC phosphorylation over that observed in the presence of Ca2+ alone. NE plus GTP induced similar increases in force and stiffness, but shortening velocity depended solely on the [Ca2+]. A regulated MLC phosphatase could explain the initial increase in force and MLC phosphorylation, but not the maintenance of enhanced force while MLC phosphorylation levels fell to values similar to those in response to Ca2+ alone. Therefore, additional elements must be involved in the maintenance of the receptor and G protein-dependent increase in myofilament Ca2+ sensitivity.

Animals↗

PubMed1992

Anemia and neutropenia in a case of copper deficiency: role of copper in normal hematopoiesis.

We present a patient who developed severe anemia and neutropenia after receiving parenteral nutrition for 2.5 years. The serum levels of copper and ceruloplasmin were low, and the bone marrow showed the presence of ringed sideroblasts and vacuolated immature cells. The administration of copper chloride by bolus injection led to a rapid improvement in anemia and neutropenia. The number of progenitor cells (colony-forming unit-granulocyte-macrophage and erythrocyte) present before the copper supplementation was well preserved. It is therefore suggested that copper enzymes play an important role in the maturation of hematopoietic cells.

Aged↗

PubMed1992

Prenatal diagnosis and obstetrical management of May-Hegglin anomaly: a case report.

A case of May-Hegglin anomaly, a rare autosomal dominant thrombocytopenia, is reported. This disorder is characterized by giant platelets, basophilic inclusion bodies within the cytoplasm of granulocytes and an occasional bleeding tendency. This bleeding tendency depends on the platelet count. The fetuses of such patients run the risk of intracranial hemorrhage in utero and during the early neonatal period following vaginal delivery. Prenatal diagnosis of this disorder has not yet been reported. We describe a case of this disorder, diagnosed in pregnancy, which, following prenatal diagnosis of mild thrombocytopenia in the fetus and confirmation by cordocentesis, could successfully undergo a vaginal delivery.

Blood Platelets↗

PubMed1992

Endothelin increases myofilament Ca2+ sensitivity in alpha-toxin-permeabilized rabbit mesenteric artery.

This study was designed to investigate the mechanism of endothelin-1 (ET-1) contractions in Staphylococcus alpha-toxin-permeabilized vascular smooth muscle. Rabbit small mesenteric arteries permeabilized with alpha-toxin were mounted for isometric or isotonic force recording or were processed for determination of myosin light chain (MLC) phosphorylation levels. Addition of 100 nM ET-1 plus 10 microM GTP significantly enhanced myofilament Ca2+ sensitivity as compared with the addition of Ca2+ alone (EC50, 0.47 microM Ca2+ for Ca2+ alone and 0.13 microM Ca2+ for ET-1 plus (GTP). This enhanced sensitivity was reversed by GDP beta S. ET-1-induced contractions were relaxed at a constant [Ca2+] by the addition of 30 microM cAMP or cGMP, demonstrating a direct effect of the cyclic nucleotides on contractile regulation. Inhibition of protein kinase C activity by 100 nM staurosporine relaxed ET-1 plus GTP-induced contractions, and pretreatment with 40 microM chelerythrine inhibited the ET-1 plus GTP increase in force. At 0.32 microM Ca2+, steady-state levels of shortening velocity were not increased by ET-1 plus GTP, although steady-state levels of MLC phosphorylation were significantly enhanced. The ET-1-induced increase in MLC phosphorylation was not altered by changes in [Ca2+], whereas the shortening velocity was Ca2+ dependent, suggesting that the increase MLC phosphorylation level may be the result of protein kinase C, rather than MLC kinase, activation. These results are consistent with the hypothesis that ET-1 increases myofilament Ca2+ sensitivity by a G protein-dependent pathway and subsequent activation of protein kinase C.(ABSTRACT TRUNCATED AT 250 WORDS)

Actin Cytoskeleton↗

PubMed1992

Increases in cerebral blood flow in rat hippocampus after medial septal injection of naloxone.

BACKGROUND AND PURPOSE: In a previous study, we occasionally found that the rat given naloxone in the preoptic region develops behavioral seizures. In view of knowledge that the forebrain including the medial septal nucleus provides cholinergic projections to the hippocampal formation, the present study examined the effects of naloxone injected into the medial septal nucleus on the local blood flow in the hippocampus. METHODS: A polyurethane-coated platinum electrode with a 1-mm bare tip for measurement of blood flow and a guide cannula made of stainless steel tube for naloxone injection were implanted chronically into the brain. The cerebral blood flow was measured by the hydrogen clearance method in freely moving rats. RESULTS: The injection of 50 micrograms naloxone caused a significant increase in hippocampal blood flow, with its peak at 20 minutes. Twenty micrograms naloxone caused a similar increase, but 10 micrograms caused only a slight increase that peaked at 30 minutes, suggesting a dose-response of naloxone effect. Hippocampal blood flow was not changed after the injection of saline into the medial septal nucleus and after the injection of naloxone into the caudate nucleus. CONCLUSIONS: Taken together with previous findings, the results suggest that endogenous opioids exert a decreasing effect on the local blood flow in the hippocampus, probably mediated by the magnocellular cholinergic neurons projecting to the hippocampus.

Animals↗

PubMed1992

Cardiac tamponade in chronic myelomonocytic leukemia: a case report.

Serous effusion is a rare complication of chronic myelomonocytic leukemia. We present a patient with chronic myelomonocytic leukemia who developed a massive pericardial effusion with cardiac tamponade as early manifestations. Numerous clumps of monocytes were observed in the effusion. The patient obtained rapid relief following the intravenous administration of etoposide (100 mg daily for 5 days). Few reports have documented details of such a case.

Cardiac Tamponade↗

PubMed1992

Poly (lactic/glycolic acid) microspheres containing antigen as a novel and potential agent of immunotherapy for allergic disorders.

In order to establish a safer and simpler antigen administration method in immunotherapy, we prepared biodegradable microspheres containing antigen and evaluated its safety and efficacy using guinea pigs. Poly (lactic/glycolic acid); (LGA) microspheres containing ovalbumin (OA) were fabricated by solvent evaporation. Over 70% of the OA was released from the microspheres within 3 days, and release was completed within 14 days in vivo. The local tissue reactions to the OA-LGA microspheres were apparently weaker than those to OA-alum. Repeated injections of high dose OA-LGA microspheres to OA-sensitized guinea pigs (high-LGA group) for 8 weeks at intervals of 2 weeks elicited an excellent therapeutic effect, i.e. a significant increase in the threshold value of antigen inhalation test, with a significant increase in IgG2 blocking antibody. The therapeutic efficacy of the high-LGA group was comparable to the conventional immunotherapy model (conventional group) and was superior to the antigen-alum model (alum group). We concluded that administration of antigen-LGA microspheres could become a new immunotherapeutic method for allergic disorders, being safer and requiring a lower frequency of antigen injections than the conventional method.

Animals↗

PubMed1992

Differences in tyrosine phosphorylated proteins between cells expressing P210bcr/abl and P190bcr/abl.

We analysed differences between the populations of tyrosine phosphorylated proteins in two cell lines, K-562 and MR-87, which express two different bcr-abl fusion gene products, using both immunoprecipitation and Western blotting with an anti-phosphotyrosine antibody. K-562 cells preferentially expressed P210bcr/abl (P210), while MR-87 expressed P190bcr/abl (P190). Tyrosine phosphorylated proteins with a molecular mass of 150 kDa (p150) and 115 kDa (p110) were found in both K-562 and MR-87. A 36 kDa protein (p36) was tyrosine phosphorylated in vivo only in K-562 cells, while proteins with a molecular mass of 140 kDa (p140) and 62 kDa (p62) were found only in MR-87 cells. Moreover, several proteins in the detergent-insoluble cell fraction were differently tyrosine phosphorylated in vitro in K-562 and MR-87 lysates. These results suggest that P210 and P190 may have different substrates, and thus, different signal transduction pathways for cell proliferation, although the differential association of such cellular proteins with the two bcr/abl products remains to be clarified.

Fusion Proteins, bcr-abl↗