Biomedical subjects

K Oda

Publications and source records attributed to K Oda.

At least 199 records · Page 11Linked to original sources

PubMed1997

Myocardial adenosine A2a receptor imaging of rabbit by PET with [11C]KF17837.

Adenosine A2a receptors are found in the endothelia, vascular smooth muscle cells and cardiac myocytes. The properties of a carbon-11 labeled A2a antagonist [11C]KF17837 ([7-methyl-11C](E)-8-(3,4-dimethoxystyryl)-1,3-dipropyl-7-methy lxa nthine) for myocardial imaging were evaluated by dynamic PET scanning of the myocardium in rabbits. Myocardial uptake of [11C]KF17837 was clearly visualized by PET. The tracer was taken up at a high level by the myocardium immediately after the injection, and the myocardial level of radioactivity gradually decreased. On the other hand, an inactive [11C]Z-isomer of [11C]KF17837 showed a very low myocardial uptake and the myocardium was not visualized with a selective A1 antagonist [11C]KF15372. By co-injection with carrier KF17837 or a xanthine type A2a antagonist 7-chlorostyrylcaffeine (CSC), the myocardial uptake of [11C]KF17837 was completely blocked. The effect of non-xanthine A2a antagonists ZM 241,385 and SCH 58,261, which have a higher affinity than CSC, was smaller than that of the CSC. The effect of weak antagonists caffeine and alloxazine or a xanthine type A1 antagonist KF15372 on the radioactivity level was small. It is concluded that PET with [11C]KF17837 can image myocardial adenosine A2a receptors.

Animals↗

PubMed1997

A stereotaxic method of anatomical localization by means of H(2)15O positron emission tomography applicable to the brain activation study in cats: registration of images of cerebral blood flow to brain atlas.

In the neuronal activation study of normal animals, precise anatomical correlation, preferentially to a detailed brain atlas, is required for the activation foci co-registration. To obtain precise regional correlation between H(2)15O-PET images and the brain atlas, a method of stereotaxic image reorientation was applied to an activation study with vibrotactile stimulation. Cats anesthetized with halothane underwent repeated measurements of regional cerebral blood flow (rCBF) in the resting condition and during vibration of the right forepaw. The image set was adjusted three-dimensionally to the atlas. The postmortem brain was sectioned according to the atlas planes. The activated areas were determined by the stimulus-minus-resting subtraction images, and the areas were projected to the atlas. The PET images of the cat brain were compatible both to the postmortem brain slices and to the brain atlas. The activation foci obtained from the subtraction images corresponded to the area around the coronal sulcus, which is electrophysiologically known as the primary sensory area as described in the atlas. There were precise regional correlations between the PET image and anatomy in a PET activation study of the cat by means of stereotaxic image reorientation.

Animals↗

PubMed1997

Immunolocalization of tissue non-specific alkaline phosphatase in mice.

Immunolocalization of tissue non-specific alkaline phosphatase (TNAP) was examined in murine tissues, employing a specific antiserum to TNAP on frozen sections, 50-micron tissue slices, and paraffin sections. TNAP was detected at high levels in hard tissues including bone, cartilage, and tooth. In bone tissue, the TNAP immunoreactivity was localized on the entire cell surface of preosteoblasts, as well as the basolateral cell membrane of osteoblasts. It was also localized on some resting chondrocytes and most of the proliferative and hypertrophic cells in cartilage. In the incisor, cells of the stratum intermedium, the subodontoblastic layer, the proximal portion of secretory ameloblasts, and the basolateral portion of odontoblasts showed particularly strong immunoreactivity. Immunoreactivity was observed in other soft tissues, such as the brush borders of proximal renal tubules in kidney, on cell membrane of the biliary canalicula in liver and in trophoblasts in the placenta. These immunolocalizations were quite similar to enzyme histochemical localizations. However, neither the submandibular gland nor the intestine, which both exhibited alkaline phosphatase activity by enzyme histochemistry, revealed immunoreactivity for TNAP. Therefore, immunocytohistochemical studies for TNAP enabled us to localize the TNAP isozyme, thus distinguishing it from other isozymes.

Alkaline Phosphatase↗

PubMed1997

Genetic analysis of signal transduction through light-induced protein phosphorylation in Neurospora crassa perithecia.

We have previously demonstrated that blue light induces the phosphorylation of a 15-kDa protein in crude membrane fractions of Neurospora crassa mycelia. Here we report the isolation and characterization of a mutant (psp; phosphorylation of small proteins that is completely defective for phosphorylation of that protein, as assayed in both crude membrane and soluble fractions. This mutation defines a unique locus that maps to linkage group VR between al-3 and his-6. To elucidate the photobiological significance of the phosphorylation of the protein, we analyzed known photobiological phenomena and discovered that the positioning of beaks on the perithecia, defined as perithecial polarity, was light-dependent in the wild type. In the psp mutant, beaks were phototropic as in the wild type, but their position was random. In a wc-l mutant, however, beaks were positioned at random and were not phototropic. Thus light-induced perithecial polarity and phototropism of perithecial beaks are controlled differently. A psp; wc-l double mutant showed the same phenotype as that of wc-l with respect to these two photomorphogenetic characters. These results indicate that the wc-l gene is epistatic to psp in the light-signal transduction pathway that controls both phototropism and perithecial polarity.

DNA-Binding Proteins↗

PubMed1997

Endothelin evokes efflux of glutamate in cultures of rat astrocytes.

Excessive release of glutamate, from glial cells as well as neurons, is thought to be a major cause of neuronal death in ischemia. To investigate glutamate release from glial cells, we measured glutamate efflux from cultures of rat astrocytes preloaded with L-[3H]glutamate. Glutamate efflux was induced by either 60 mM KCI or Na+-free medium, suggesting that the efflux is due to the reversed operation of a Na+- and K+-coupled glutamate uptake machinery. While investigating various neuropeptides and neurotransmitters, we found that endothelin (ET) specifically induced efflux of glutamate. Northern blot analysis and binding study showed that the ET type B receptor (ET(B)-R) subtype was expressed two to three times more densely than the ET type A receptor (ET(A)-R) in astrocytes. The ET(B)-R antagonist IRL 2500 partially inhibited efflux of glutamate induced by 1 nM ET-1 in a concentration-dependent manner, causing a maximal inhibition of 60% at 1 microM. However, the ET(A)-R antagonist BQ-123 did not cause significant inhibition even at 10 microM. Combination of both antagonists completely inhibited the ET-1-induced efflux. These results indicate that both receptor subtypes are involved in efflux of glutamate with a major contribution from the ET(B)-R. Our findings suggest that ET, which is known to be released in ischemia, may exacerbate neurodegeneration by stimulating efflux of glutamate.

Animals↗

PubMed1997

Induction of IL-1 beta-converting enzyme-independent apoptosis by IL-2 in human T cell lines.

Our previous study demonstrated that IL-2 suppressed growth of human T cell lines, in which the suppression was observed with members among HTLV-I-infected T cell lines independent of IL-2 for growth. In this study, we examined the molecular mechanism of IL-2-induced growth suppression with two HTLV-I-infected T cell lines; TL-OmI expressing endogenously three subunits, i.e. alpha, beta and gamma chains, of the IL-2 receptor, and an MT-1 transfectant expressing the endogenous alpha and gamma chains and exogenous beta chain. Our analysis revealed that IL-2 induced apoptosis in both T cell lines. Experiments with inhibitors for the proteases responsible for apoptosis signals showed that caspase 1 (IL-1 beta-converting enzyme) was not involved in apoptosis induced by IL-2. Other MT-1 sublines introduced with mutant beta chains demonstrated that IL-2-induced apoptosis required signals from both the serine-rich (S) region and acidic (A) region of the IL-2 receptor beta chain, which are essential but not critical for IL-2-mediated cell growth respectively. Collectively, IL-2 functions not only on growth promotion and prevention of apoptosis but also on induction of apoptosis, which may be implicated in physiological regulation of immune reactions by controlling growth and activation of T cells.

Apoptosis↗

PubMed1997

Abundance, parity, and Japanese encephalitis virus infection of mosquitoes (Diptera:Culicidae) in Sepang District, Malaysia.

A 2-yr study of Japanese encephalitis (JE) virus in Sepang District, Selangor, Malaysia, was carried out to identify the mosquito vectors and to determine their seasonal abundance, parity, and infection rates. In total, 81,889 mosquitoes belonging to 9 genera and > 50 species were identified from CDC trap collections augmented with dry ice during 1992 and 1993. Culex tritaeniorhynchus Giles and Culex gelidus Giles were the most abundant species, and both increased in numbers with increases in rainfall. Overall, 45 JE virus isolations were made from 7 species-Cx. tritaeniorhynchus (24), Cx. gelidus (12), Culex fuscocephala Theobald (2), Aedes butleri Theobald (4), Culex quinquefasciatus Say (1), Aedes lineatopennis Ludlow (1), and Aedes (Cancraedes) sp. (1). Based on elevated abundance and JE infection rates, Cx. tritaeniorhynchus appears to be the most important vector of JE virus in Sepang.

Aedes↗

PubMed1997

Identification of reactive site of a proteinaceous metalloproteinase inhibitor from Streptomyces nigrescens TK-23.

Streptomyces metalloproteinase inhibitor (SMPI), isolated from Streptomyces nigrescens TK-23, is a small proteinaceous metalloproteinase inhibitor consisting of 102 amino acid residues and two disulfide bridges. SMPI specifically inhibits metalloproteinases such as thermolysin. After prolonged incubation with a catalytic amount of thermolysin, it is cleaved at Cys64-Val65 [Murai, H., Hara, S., Ikenaka, T., Oda, K., and Murao, S. (1985) J. Biochem. 97, 173-180]. Hence, for identification of the reactive site, mutants were constructed by substituting Val65 with various amino acid residues (Leu, Ile, Phe, Tyr, Gly, Ser, Lys, and Glu). The mutants were analyzed for inhibitory activity. Among them, V65I, V65L, V65F, and V65Y retained strong inhibitory activity, whereas V65S, V65G, V65K, and V65E showed very weak inhibitory activity against thermolysin. The Ki values were found to be of the order of 10(10) M by using a fluorogenic substrate, MOCAc-Pro-Leu-Gly-Leu-A2pr(Dnp)-Ala-Arg-NH2. In addition, susceptibility to enzyme degradation was analyzed by means of limited proteolysis with thermolysin. Mutants which retained strong inhibitory activity were cleaved by thermolysin only at the reactive site, in the same way as native SMPI. The mutants which showed weak inhibitory activity underwent rapid degradation. These results were consistent with the substrate specificity of thermolysin. Based on these results, the reactive site of SMPI was identified as Cys64-Val65.

Bacterial Proteins↗

PubMed1997

Resynthesis of reactive site peptide bond and temporary inhibition of Streptomyces metalloproteinase inhibitor.

Streptomyces metalloproteinase inhibitor (SMPI) is a small proteinaceous inhibitor which inhibits metalloproteinases such as thermolysin (Ki =1.14 x 10(-10) M). When incubated with the enzyme, it is gradually hydrolyzed at the Cys64-Val65 peptide bond, which was identified as the reactive site by mutational analysis. To achieve a further understanding of the inhibition mechanism, we attempted to resynthesize the cleaved reactive site by using the enzyme catalytic action. The native inhibitor was resynthesized from the modified inhibitor (Ki =2.18 x 10(-8) M) by incubation with a catalytic amount of thermolysin under the same conditions as used for hydrolysis (pH 7.5, 25 degrees C), suggesting that SMPI follows the standard mechanism of inhibition of serine proteinase inhibitors. Temporary inhibition was observed when the native inhibitor and thermolysin were incubated at a 1:100 (mol/mol) enzyme-inhibitor ratio at 37 degrees C. SMPI showed temporary inhibition towards all the enzymes it inhibited. The inhibitory spectrum of SMPI was analyzed with various metalloproteinases based on the Ki values and limited proteolysis patterns. Pseudomonas elastase and Streptomyces griseus metalloproteinase II formed more stable complexes and showed much lower Ki values (approximately 2 pM) than thermolysin. In the limited proteolysis experiments weak inhibitors were degraded by the enzymes. SMPI did not inhibit almelysin, Streptomyces caespitosus neutral proteinase or matrix metalloproteinases. SMPI specifically inhibits metalloproteinases which are sensitive to phosphoramidon.

Binding Sites↗

PubMed1997

Gastrointestinal autonomic nerve tumor with giant abscess. A case report and literature review.

We report a gastrointestinal autonomic nerve tumor of the stomach with a giant abscess. The patient had fever and pain and was found to have anemia and an abdominal mass. X-ray and endoscopic examination showed a gastric submucosal tumor with a fistula to the gastric lumen. Partial gastrectomy was performed and no metastasis was found. On gross examination, the excised tumor was seen to be a submucosal solid tumor with a giant abscess. Alpha streptococci and anaerobic gram-negative rods were cultured from the pus of the abscess. The tumor resembled a gastric myogenic tumor composed of spindle cells, partly showing storiform and epithelioids. Tumor cells showed positive staining for vimentin and neuron-specific enolase but were negative for desmin, alpha-smooth muscle actin, and S-100 protein. Ultrastructural examination showed remarkable interdigitation of cytoplasmic processes with neurosecretory granules between the tumor cells. This lesion was similar to previously described gastrointestinal autonomic nerve tumors. Gastrointestinal autonomic nerve tumors are a rare, distinct subtype of gastrointestinal stromal tumors; although several cases of focally necrotic tumors have been reported, there has been only one report of the tumor with an abscess, as in our case.

Abscess↗

PubMed1997

Efficient protein production using a Bombyx mori nuclear polyhedrosis virus lacking the cysteine proteinase gene.

Infection by a baculovirus (Bombyx mori nuclear polyhedrosis virus, BmNPV) in silkworm (Bombyx mori) larvae is highly efficient as an expression system for the production of useful proteins. However, the amount of the protein of interest expressed tends to decrease in the later stages of infection presumably due, in part, to a proteinase produced in the larval haemolymph. The N-terminal amino acid sequence of a proteinase purified from the haemolymph of BmNPV-infected larvae was identical to the internal amino acid sequence of the viral cysteine proteinase gene of BmNPV, suggesting that the cysteine proteinase in the haemolymph originated from the BmNPV gene. We constructed a mutant virus (CPd) which had a deletion in the cysteine proteinase gene. No proteinase activity corresponding to this proteinase was detected in the haemolymph of silkworm larvae infected with CPd. The firefly luciferase and the human growth hormone genes were separately introduced into CPd under control of the polyhedrin promoter. These constructs produced these proteins very efficiently, because of a greatly reduced degree of degradation of these proteins. A BmNPV vector system using CPd enhances the stability of foreign expressed proteins, especially for those that are cysteine proteinase-sensitive.

Animals↗

PubMed1997

Synthesis and antitumor activity of 9-acyloxyellipticines.

Various kinds of water-soluble 9-acyloxyellipticine derivatives were synthesized in a search for compounds with potent antitumor activity. Antitumor activities against several tumors in mice (P388 leukemia, colon 26, Lewis lung carcinoma and B16 melanoma) were evaluated by using intravenous administration. Many compounds exhibited good antitumor activities; in particular, the glutarate derivative (5o) showed potent antitumor activity. This compound (5o) may be converted to 9-hydroxyellipticine (2) by enzyme-catalyzed hydrolysis in the body.

Animals↗

PubMed1997

Synthesis and antitumor activity of quaternary salts of 2-(2'-oxoalkoxy)-9-hydroxyellipticines.

Various kinds of water-soluble quaternary salts of 2-(2'-oxoalkoxy)-9-hydroxyellipticines were synthesized in a search for compounds with potent antitumor activity and low toxicity. Some compounds exhibited more potent antitumor activities than elliptinium (1) and SUN 4599 (3). In particular, 2-(3'-methoxy-2'-oxopropanoxy)-9- hydroxy-5,11-dimethyl-6H-pyrido[4,3-b]carbazolium bromide (4d) showed potent antitumor activities against P388 leukemia, colon 26, and Lewis lung carcinoma.

Animals↗

PubMed1997

Purification and characterization of glutamate decarboxylase from Lactobacillus brevis IFO 12005.

Glutamate decarboxylase (GAD) [EC 4.1.1.15] was purified from a cell-free extract of Lactobacillus brevis IFO 12005 by chromatographies on Sephadex G-100, DEAE-Sepharose CL-6B, and Mono Q. About 9 mg of purified GAD was obtained from 90.2 g of wet cells. The purified preparation showed a single protein band on SDS-PAGE. The molecular weights of purified GAD by SDS-PAGE and gel filtration on Superdex 200 were 60,000 and 120,000, respectively, indicating that GAD from L. brevis exists as a dimer. The N-terminal amino acid sequence of the purified GAD was NH2-Met-Asn-Lys-Asn-Asp-Gln-Glu-Gln-Thr-. The optimum pH and temperature of GAD were at pH 4.2 and at 30 degrees C. The GAD activity was increased by the addition of sulfate ions in a dose-dependent manner. The order of effects was as follows: ammonium sulfate > sodium sulfate > magnesium sulfate, indicating that the increase of hydrophobic interaction between subunits causes the increase of GAD activity. The purified GAD reacted only with L-glutamic acid as a substrate and the K(m), kcat, and kcat/K(m) values were 9.3 mM, 6.5 S-1, and 7 x 10(2) M-1 S-1, respectively.

Amino Acid Sequence↗

PubMed1997

Purification and characterization of cysteine proteinase from a baculovirus gene.

To analyze the degradation of product proteins at the late stage of virus infection in the baculovirus expression system, a cysteine proteinase was purified from hemolymph of Bombyx mori infected with wild-type B. mori nuclear polyhedorosis virus (BmNPV). The purified cysteine proteinase preparation had two protein bands (major 35-kDa active protein and 28-kDa inactive protein) on SDS-PAGE. Based on the N-terminal amino acid sequences of them, it was found that both proteins originated in the cysteine proteinase gene of BmNPV. The purified cysteine proteinase had an optimum pH at 4.0, and also had activities at neutral pHs. When recombinant luciferase was used as a natural substrate, it was degraded rapidly by the cysteine proteinase at the physiological pH of hemolymph. These results suggest that the cysteine proteinase from a BmNPV gene participates in the degradation of foreign protein expressed by the baculovirus system.

Amino Acid Sequence↗

PubMed1997

Isolation and some properties of sorbitol oxidase from Streptomyces sp. H-7775.

A sorbitol oxidase (SOX) was found in the cell-free extract of a strain isolated from soil. The strain was classified and designated as Streptomyces sp. H-7775. SOX is constitutively expressed in the cell. The molecular weight of SOX that purified from the cell-free extract was 45,000. The optimum pH and the K(m) for sorbitol were 6.5-7.5 and 0.26 mM, respectively. The prosthetic group was a covalently bound FAD. SOX catalyzed oxidation of D-sorbitol to glucose and hydrogen peroxide without any requirements of exogenous cofactors. SOX did not react with glucose, a reaction product of D-sorbitol. This feature is useful in its application for diagnosis.

Chromatography, Affinity↗

PubMed1997

Isolation and characterization of chitinase from a flake-chitin degrading marine bacterium, Aeromonas hydrophila H-2330.

A flake-chitin degrading marine bacterium was isolated and identified as Aeromonas hydrophila. This strain secreted five chitinases and an beta-N-acetylglucosaminidase. The main chitinase (Chi-A) was purified and characterized. The optimum pH of Chi-A was 5-8, and the activity was inhibited by Hg2+ and Fe3+. Chi-A was different from chitinases of other Aeromonas species with respect to molecular weight (62,000) and insensitivity to monoiodoacetate. The amino-terminal amino acid sequence showed extensive similarity with chitinases from Gram-negative bacteria.

Aeromonas hydrophila↗

PubMed1997

A novel metalloproteinase, almelysin, from a marine bacterium, Alteromonas sp. No. 3696: purification and characterization.

We have discovered a novel metalloproteinase, which has high activity at low temperatures, from the culture supernatant of a marine bacterium. The strain was identified as Alteromonas sp. No. 3696. The metalloproteinase, named almelysin, was purified to homogeneity from the cultured supernatant at 10 degrees C by two column chromatographies. About 20 mg of purified almelysin was obtained from 18.4 liters of the culture supernatant. The molecular mass of almelysin was estimated to be 28 kDa by SDS-PAGE and the isoelectric point was 4.3. The optimum pH for activity of almelysin was pH 8.5-9.0 and 6.5 using casein and (7-methoxycoumarin-4-yl)acetyl(MOCAc)-Pro-Leu-Gly-Leu-(N3- [2,4-dinitrophenyl]-L-2,3-diaminopropionyl) [A2pr(Dnp)]-Ala-Arg-NH2 as substrates, respectively. Almelysin was stable between pH 7.5-8.0 and below 40 degrees C. The optimum temperature for the activity was observed to be 40 degrees C using both casein and MOCAc-Pro-Leu-Gly-Leu-A2pr(Dnp)-Ala-Arg-NH2 as substrates. The activity of almelysin was inhibited by such metallo chelators as EDTA and o-phenanthroline, while talopeptin, phosphoramidon, and SMPI, typical metalloproteinase inhibitors, had no effect. Almelysin primarily cleaved the Ala14-Leu15 bond and Phe24-Phe25 bond, and secondarily the Tyr16-Leu17 bond in oxidized insulin B-chain. However, almelysin could not cleave the His5-Leu6, His10-Leu11, and Gly23-Phe24 bonds, which were cleaved by other metalloproteinases. These results indicate that the substrate specificity of almelysin is different from other metalloproteinases. Interestingly, Alteromonas sp. No. 3696 strain produced another proteinase as well as almelysin at 25 degrees C.

Amino Acid Sequence↗