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Biomedical subjects

T Isobe

Publications and source records attributed to T Isobe.

At least 181 records · Page 10Linked to original sources
PubMed1991

A novel protein induced in cortical epileptic focus of rat cerebrum: a possible linkage to epileptogenesis.

To precisely evaluate a protein-related mechanism of epileptogenesis, we quantitatively analyzed the 70-kDa protein (namely, P70), a specific protein found in the cobalt-induced epileptic focus, and examined its effect on the electrocorticogram (ECoG) and cortical neurons in cerebral slices and its immunocytochemical localization in rats. Cobalt-induced cortical epileptogenic cortex exhibited a marked induction of P70. Its initiation time was ahead of the generation of epileptogenic activities. The anticonvulsant phenytoin (PHT) attenuated the cobalt-induced epileptogenic activities, but failed to suppress protein induction. Injection of this protein into the motor region of normal rat cerebral cortex elicited an epileptic ECoG and behavioral seizures. It also caused epileptiform activity with paroxysmal depolarization shifts in cortical neurons. These epileptogenic phenomena elicited by P70 were abolished by prior treatment with PHT or phenobarbital. Immunocytochemical analysis with an antiserum against P70 revealed that the reactivity was confined to pyramidal cells only in the region of the focus and was mainly localized on somatic, dendritic, and nuclear membranes and microtubles. These findings suggest that P70 may be linked to epileptogenesis.

Animals↗
PubMed1991

Molecular cloning of cDNA to rat 14-3-3 eta chain polypeptide and the neuronal expression of the mRNA in the central nervous system.

Activation of tyrosine and tryptophan hydroxylases, key enzymes for the catecholamine and serotonin biosynthesis, requires Ca2+/calmodulin-dependent protein kinase II and 14-3-3 protein which comprises a family of, at least, seven polypeptides in the bovine. Here we show that the amino acid sequence of the rat 14-3-3 eta chain deduced from the nucleotide sequence is completely identical to that of bovine counterpart. Using in situ hybridization the expression of mRNA for this protein is detected not only in the monoamine-synthetic neurons but also in many other discrete nuclei which synthesize neither catecholamine nor serotonin. The highly conservative structure between mammalian species and wider expression of this protein than expected in the central nervous system suggest that the 14-3-3 protein exerts some, though yet to be defined, functions fundamental to neuronal activities other than activation of the monoamine biosynthesis.

14-3-3 Proteins↗
PubMed1991

Widespread distribution of the 14-3-3 protein in vertebrate brains and bovine tissues: correlation with the distributions of calcium-dependent protein kinases.

A highly specific antiserum was prepared against bovine brain 14-3-3 protein, a protein kinase-dependent activator of tyrosine and tryptophan hydroxylases. The immunoassay using this antiserum proved the presence of 14-3-3 protein in various bovine tissues and in brains of various vertebrate species. The quantitative analysis indicated that the tissue distribution of 14-3-3 protein is more closely related to the known distributions of the Ca2(+)-dependent protein kinases, i.e., Ca2+/calmodulin- and Ca2+/phospholipid-dependent protein kinases, rather than those of tyrosine and tryptophan hydroxylases. This result, together with the available data on this protein, suggests potential roles of the 14-3-3 protein in more diverse kinase-mediated processes than the predicted role in monoamine synthesis.

14-3-3 Proteins↗
PubMed1991

[Ectopic salivary amylase-producing IgA- lambda-type multiple myeloma with expression of MDR-1/P-glycoprotein].

We report a case of ectopic salivary amylase-producing IgA- lambda-type multiple myeloma. A 70-year-old man was admitted because of anemia and renal failure. After chemotherapy for eight months, the serum amylase markedly increased. Amylase activity in the supernatant of cultured myeloma cells, which were obtained from the bone marrow, also increased. The myeloma cells expressed MDR-1/P-glycoprotein). The case implies the association of drug resistance and the ectopic amylase production in a case of multiple myeloma.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1990

Purification of D2 dopamine receptor by photoaffinity labelling, high-performance liquid chromatography and preparative sodium dodecyl sulphate polyacrylamide gel electrophoresis.

[125I]N-azidophenethylspiperone ([125I]azido-NAPS) was used as a photoaffinity ligand for bovine D2 dopamine receptor. On photolysis, [125I]azido-NAPS was covalently incorporated into a major band of 94 kDa in bovine striatal membrane as assessed by autoradiography after sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) (10% acrylamide gel). The labelled D2 receptor protein from striatal membrane was solubilized and subjected to HPLC using gel filtration (TSK G3000SW) and hydroxyapatite gel (Pentax SH2010C), followed by two steps of preparative SDS-PAGE. The D2 receptor protein could be obtained as a single major polypeptide on SDS-PAGE by either silver staining or autoradiography.

Affinity Labels↗
PubMed1990

Large-scale purification of bovine brain lactate dehydrogenase by affinity chromatography on immobilized colchicine.

Lactate dehydrogenase (LDH) [EC 1.1.1.27] in a crude extract (40-80% ammonium sulfate fraction) of bovine brain was adsorbed on an immobilized colchicine column and specifically eluted by addition of 1 mM NADH. The purity and subunit composition of the pooled LDH were estimated by two-dimensional gel electrophoresis. With an increase of NaCl concentration from 0 to 2.0 M, ligand saturation of LDH on immobilized colchicine increased from 6.8 to 14%, whereas that on immobilized Cibacron blue F3GA decreased from 2.1 to 0%. In the presence of high NaCl concentration, immobilized colchicine enabled both large- and small-scale purification of LDH by affinity chromatography and resulted in a yield of 117 mg from 1 kg of bovine brain in the presence of 2.5 M NaCl or higher recoveries of 54-96% from various tissues of one rat in the presence of 1.0 M NaCl. These results indicate that immobilized colchicine is an excellent adsorbent for the isolation and purification of LDH by affinity chromatography and has a high LDH-adsorbing capacity dependent upon a high NaCl concentration. Kinetic studies revealed that colchicine apparently competed with cofactor NAD for the active site of LDH and the Ki values of colchicine decreased with an increase of NaCl concentration. The chemical specificity of the colchicine-binding site of LDH was studied by the use of colchicine analogues and it is concluded that both the tropolone moiety (C-ring) and the amido bond in a side chain of colchicine structure are essential to the colchicine-LDH interaction.

Animals↗
PubMed1990

Early schizonts of Leucocytozoon caulleryi.

Sporozoites of Leucocytozoon caulleryi were inoculated intravenously into 26-day-old specific pathogen-free chickens. Six days after inoculation, early schizonts were detected in lung, spleen, and thymus. They existed separately and were spherical or ovoid, 30-35 microns in diameter, and had well defined walls.

Animals↗
PubMed1990

Dual infections of Eimeria tenella and Escherichia coli in chickens.

The interactive effects of Eimeria tenella and Escherichia coli infection in chickens were investigated. Specific pathogen free chickens inoculated orally with E tenella and challenged four days later with E coli via the air sac showed more severe acute septicaemic lesions and subacute serositis than chickens given E coli alone. Moreover, caecal lesions induced by E tenella were more severe in chickens given both E tenella and E coli than in those given E tenella alone. In contrast, oral inoculation of E coli did not result in acute septicaemic lesions or subacute serositis and had no effect on the severity of the caecal lesions caused by E tenella.

Animals↗
PubMed1990

[Complete remission in multiple myeloma with natural interferon-alpha (HLBI) and melphalan/prednisolone intermittent therapy].

A 46-year-old man was admitted because of lumbago and numbness of the left leg. Pelvic X-ray showed a large defect in the left sacrum and CT revealed multiple punched-out lesions. Serum IgA was 1,740 mg/dl with a monoclonal component of IgA kappa by serum electroimmunofixation. Bence Jones protein of kappa type was detected in urine. Diagnosis of myeloma was made on the basis of histology of the biopsied sacral tumor. Repeated melphalan/prednisolone intermittent therapy (MP) was done with concomitant administration of natural interferon-alpha (IFN-alpha) 3 X 10(6) U intramuscularly for 67 days. Performance status including gait markedly improved. Normal bone marrow morphology and disappearance of M-protein by electroimmunofixation were achieved after 13 cycles of MP, when pelvic X-ray revealed prominent recalcification. No further treatment was instituted for subsequent 6 months, without any demonstrable M-protein. Complete remission of myeloma is rare with conventional therapies and thus new therapeutic modalities have been waited for. IFN-alpha may promise better responses if appropriately combined with other chemotherapies.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1989

Molecular cloning of a full-length cDNA for human alpha-N-acetylgalactosaminidase (alpha-galactosidase B).

In the process of molecular cloning of cDNA for proteins associated with a purified human placental sialidase fraction, we discovered one of the proteins with apparent molecular weight of 46 kDa is in reality alpha-N-acetylgalactosaminidase. The full length cDNA, pcD-HS1204, codes for 358 amino acids with the first 17 residues representing a putative signal peptide. The predicted amino acid sequence shows striking homology with human alpha-galactosidase A and yeast alpha-galactosidase. The substrate specificities as well as the behavior of the 46 kDa protein on hydroxylapatite chromatography confirmed that the 46 kDa protein is in reality alpha-N-acetylgalactosaminidase.

Amino Acid Sequence↗
PubMed1989

Specific purification of glyceraldehyde-3-phosphate dehydrogenase by hydrophobic chromatography on immobilized colchicine.

Hydrophobic column chromatography of bovine brain extracts (40-80% ammonium sulfate fraction) on immobilized colchicine resulted in the selective elution of one major protein with decreasing ionic strength of medium. This protein was identified as glyceraldehyde-3-phosphate dehydrogenase (GAPDH; EC 1.2.1.1) on the basis of its biochemical properties, N-terminal amino-acid sequence and enzymatic activity. The present method enabled GAPDH to be isolated with a high recovery (80%; 184 mg/kg brain) and could be of potential use for the purification of GAPDH from various tissues.

Amino Acid Sequence↗
PubMed1989

[Studies on the constituents of Leucoseptrum stellipillum].

Flavonoids, triterpenoids, and steroids were isolated from the leaves of Leucoseptrum stellipillum (MIQ). Kitamura et Murata and identified as apigenin, luteolin, chrysoeriol, ursolic acid, pomolic acid, tormentic acid, beta-sitosterol, and beta-sitosterol glucoside by comparison of their spectral data with those of authentic specimens. Among these compounds, the triterpenoids showed significant antibacterial activities against Streptococcus mutans.

Bacteria↗
PubMed1989

Chemistry and cell biology of neuron- and glia-specific proteins.

Studies of proteins specific to a certain type of cell are of general interest because these proteins may be involved in the determination of morphological and functional characteristics of the cell. In the nervous tissue, many "neuron-specific" and "glia-specific" proteins have been identified by various biochemical and immunohistochemical means and their relationships to cell functions have been studied. This paper briefly reviews our studies on the chemical and cell-biological aspects of the neuron- and glia-specific proteins, with special reference to the 14-3-3 protein and the S100 protein. Our studies suggest that glial protein S100 may be involved in the regulation of cell growth and differentiation, while neuronal protein 14-3-3, in the regulation of serotonin and catecholamine biosynthesis in neurons and other monoamine-synthesizing cells.

14-3-3 Proteins↗
PubMed1989

IgG and IgA enhance the chrysotile-induced production of reactive oxygen metabolites by human polymorphonuclear leucocytes.

Chrysotile asbestos fibres induce a rapid generation of reactive oxygen metabolites by human polymorphonuclear leucocytes (PMNL) in vitro. This effect was markedly enhanced by the presence of 10-200 micrograms/ml of human gammaglobulin, purified polyclonal IgG, and monoclonal IgG and IgA myeloma proteins. Purified monoclonal IgD, IgM, kappa light chain proteins, and secretory IgA inhibited this chrysotile-induced response. No enhancing effect of IgG was observed when quartz dust or opsonized zymosan were used as stimulators of PMNL metabolism. The enhancing effect of IgG was shown to depend on opsonization of the asbestos fibre. We suggest that the IgG and IgA potentiating effect on the asbestos fibre-induced production of tissue-damaging reactive oxygen metabolites by inflammatory cells is dependent on a particle-specific binding of immunoglobulin to the fibre surface, with subsequent Fc receptor-mediated effects on cells. Such an interaction between certain immunoglobulins and asbestos may explain a number of in vivo phenomena in which immunological responses (hypergammaglobulinemia, circulating immune complexes, etc.) have been shown to relate to the progression of pulmonary asbestosis. The differences between various immunoglobulin classes and monoclonal immunoglobulins could represent an individual inflammation-modulating mechanism in the development of acute or chronic pulmonary asbestosis.

Asbestos↗
PubMed1988

Molecular cloning of cDNA coding for brain-specific 14-3-3 protein, a protein kinase-dependent activator of tyrosine and tryptophan hydroxylases.

The 14-3-3 protein is a family of acidic proteins present exclusively in the brain and is believed to have a function in monoamine biosynthesis because of its ability to activate tyrosine hydroxylase and tryptophan hydroxylase in the presence of Ca2+/calmodulin-dependent protein kinase type II. In this study, we resolved bovine brain 14-3-3 protein into seven polypeptide components by means of reversed-phase chromatography and determined the amino acid sequence of one of these components (eta chain) by cloning its cDNA from a bovine cerebellum cDNA library. The eta-chain mRNA is 1.8 kilobases long and encodes a polypeptide of 246 amino acids and Mr 28,221. Computer-assisted analysis of the sequence indicates that the eta chain exhibits no internal sequence repeats, nor does it have significant sequence similarity to other proteins with known amino acid sequence. However, the eta chain appears to consist of two structural regions that are distinguishable in their clearly different charge characteristics: the almost neutral amino-terminal region and the strongly acidic carboxyl-terminal region. The structural features of the eta chain and the domain organization of tyrosine and tryptophan hydroxylases suggest that the 14-3-3 protein binds to the regulatory domain of the phosphorylated hydroxylases through its acidic carboxyl-terminal region and activates the hydroxylases by inducing an active conformation.

14-3-3 Proteins↗