101
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Oikawa K, Ohkohchi N, Sato M, Satomi S. The effects of the elimination of Kupffer cells in the isolated perfused liver from non-heart-beating rat. Transpl Int 2001; 13 Suppl 1:S573-9. [PMID: 11112077 DOI: 10.1007/s001470050406] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
We examined the effect of elimination of Kupffer cells on the sinusoidal microcirculation in graft harvested from non-heart-beating donors (NHBD), focusing on the arachidonic acid cascade and cytokines. Cardiac arrest was induced by thoracotomy. Livers were harvested 30 min after thoracotomy and perfused by Krebs-Henseleit bicarbonate buffer for 60 min after 6 h cold preservation. For the elimination of Kupffer cells, rats were pretreated liposome-encapsulated dichloromethylene diphosphonate (KE group). Eicosanoids (TXB2, 6-keto-PGF1alpha, LTB4) and cytokines (TNFalpha, IL-1beta) in the perfusate were measured. Histological examination was also carried out. In the KE group, the value of TXB2 was suppressed completely and cytokines were reduced, and sinusoidal structures and hepatocytes were well protected. These results indicated that the elimination of Kupffer cells improved sinusoidal microcirculation in NHBD and liver transplantation using grafts from NHBD could be made to succeed by modulation of Kupffer cells.
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102
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Kagawa T, Sakai T, Suetsugu N, Oikawa K, Ishiguro S, Kato T, Tabata S, Okada K, Wada M. Arabidopsis NPL1: a phototropin homolog controlling the chloroplast high-light avoidance response. Science 2001; 291:2138-41. [PMID: 11251116 DOI: 10.1126/science.291.5511.2138] [Citation(s) in RCA: 442] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Chloroplasts relocate their positions in a cell in response to the intensity of incident light, moving to the side wall of the cell to avoid strong light, but gathering at the front face under weak light to maximize light interception. Here, Arabidopsis thaliana mutants defective in the avoidance response were isolated, and the mutated gene was identified as NPL1 (NPH-like 1), a homolog of NPH1 (nonphototropic hypocotyl 1), a blue light receptor used in phototropism. Hence, NPL1 is likely a blue light receptor regulating the avoidance response under strong light.
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103
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Oikawa K, Kamimura H, Watanabe T, Miyamoto I, Higuchi S. Pharmacokinetic properties of a novel tissue-type plasminogen activator pamiteplase after single intravenous administration to rats, dogs, and monkeys. Thromb Res 2001; 101:493-500. [PMID: 11323007 DOI: 10.1016/s0049-3848(00)00414-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The pharmacokinetics of pamiteplase and recombinant tissue-type plasminogen activator (rt-PA) in rats, dogs, and monkeys were examined using a newly developed enzyme-linked immunosorbent assay (ELISA). Plasma concentrations after intravenous administration of pamiteplase to rats declined in a triphasic manner. Plasma concentrations after intravenous administration of pamiteplase to dogs or monkeys declined in a biphasic manner. The area under the plasma concentration-time curve from zero to infinity (AUC(0-->infinity)) in rats and dogs increased with increasing dose. The half-life and mean residence time of pamiteplase in rats, dogs, and monkeys were shown to be longer than those of rt-PA. Total clearance (CL(total)) of pamiteplase was only 7-16% that of rt-PAs, suggesting that concentrations of pamiteplase in plasma were higher and more continuous than those of rt-PA in these experimental animals. The data suggest that a bolus administration of pamiteplase shows the same thrombolytic activity as continuous infusion of rt-PA in experimentally induced thrombosis in rats and dogs. The pharmacokinetic parameters distribution volume at the steady state and CL(total) calculated by immunoreactive concentration after administration of pamiteplase to rats, dogs, and monkeys show high correlation with body weights (r(2)=.7728 and .9039).
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104
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Oikawa K, Ohkohchi N, Sato M, Masamune A, Satomi S. Elimination of Kupffer cells suppresses activation of nuclear factor kappa B and production of cytokines and eicosanoids in non-heart-beating donors. Transplant Proc 2001; 33:839-40. [PMID: 11267090 DOI: 10.1016/s0041-1345(00)02339-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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105
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Ichiyanagi T, Oikawa K, Tateyama C, Konishi T. Acid mediated hydrolysis of blueberry anthocyanins. Chem Pharm Bull (Tokyo) 2001; 49:114-7. [PMID: 11201215 DOI: 10.1248/cpb.49.114] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Acid mediated hydrolysis of anthocyanins was studied using capillary zone electrophoresis (CZE). A commercially available wild blueberry (Bilberry) extract was dissolved in different concentrations of TFA (0.1, 1, 3, 9%), then was subjected to thermodecomposition reaction at 95 degrees C. After the reaction, the samples were analyzed by CZE. The hydrolysis rate of each anthocyanin and the formation of the aglycon were determined by the change in the peak pattern of the anthocyanins in the electropherogram. Each anthocyanin peak decreased time dependently in a first order kinetic fashion. It was revealed that the hydrolysis rate of each anthocyanin was determined primarily by the type of conjugated sugar and not by the aglycon structure. The rate constant of anthocyanin hydrolysis was in the following order, arabinoside>galactoside>glucoside without regard to the aglycon structure. The kinetic behavior of this anthocyanin hydrolysis together with the CZE mobility allowed us to identify an unknown CZE peak as delphinidin 3-O-beta-arabinoside. At low TFA concentration, significant decomposition of the anthocyanidin nucleus occurred, but the glycoside hydrolysis predominated at high TFA concentration. It was further revealed that the aglycon released reacted successively to form polymeric products at higher TFA conditions.
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106
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Asada T, Oikawa K. Use of an ion-exchange membrane for sample pretreatment of ion chromatography: determination of phosphate ion and sulfate ion in deep subsurface water. ANAL SCI 2001; 17:213-5. [PMID: 11993667 DOI: 10.2116/analsci.17.213] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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107
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Oikawa K, Fujiwara M, Nakazato E, Tanaka K, Takahashi H. Characterization of two plastid sigma factors, SigA1 and SigA2, that mainly function in matured chloroplasts in Nicotiana tabacum. Gene 2000; 261:221-8. [PMID: 11167008 DOI: 10.1016/s0378-1119(00)00505-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have isolated and characterized two genes from Nicotiana tabacum, whose products function as putative sigma factors for plastid RNA polymerase. Since the amino acid sequence deduced from the DNA sequences of both genes showed highly similar to that of the SigA protein of Arabidopsis thaliana, we termed the corresponding genes sigA1 and sigA2, respectively. Transient expression assay using a green fluorescent protein (GFP) fusion construct indicated that the N-terminal region of the sigA2 gene product could function as a transit peptide for import into chloroplasts. The gel-blot analysis of RNAs revealed that the sum of the sigA1 and sigA2 transcripts fluctuated apparently with an endogenous rhythm after 12-h-light, 12-h-dark entrainment in photomixotrophically cultured tobacco cells. RT-PCR based northern analysis revealed that the sigA1 and sigA2 transcripts increased along with the cell growth in cultured cells, and were most abundant in mature leaves and shoot meristems with very young leaves in tobacco plants. Immunoblot analysis of the cell extracts of tobacco plants also supports this notion. These results suggest that the sigma factors encoded by sigA1 and sigA2 play a role in chloroplast development and regulation of gene expression in matured chloroplasts.
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MESH Headings
- Amino Acid Sequence
- Blotting, Northern
- Chloroplasts/metabolism
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- DNA, Complementary/isolation & purification
- DNA, Plant/genetics
- DNA, Plant/metabolism
- Gene Expression Regulation, Plant/radiation effects
- Green Fluorescent Proteins
- Luminescent Proteins/genetics
- Luminescent Proteins/metabolism
- Microscopy, Confocal
- Molecular Sequence Data
- Photoperiod
- Phylogeny
- Plants, Toxic
- Plastids/metabolism
- Protein Isoforms/genetics
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Messenger/radiation effects
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Sequence Alignment
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Sigma Factor/genetics
- Tissue Distribution
- Nicotiana/cytology
- Nicotiana/genetics
- Nicotiana/metabolism
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108
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Zhang Y, Ohkohchi N, Oikawa K, Sasaki K, Satomi S. Assessment of viability of the liver graft in different cardiac arrest models. Transplant Proc 2000; 32:2345-7. [PMID: 11120194 DOI: 10.1016/s0041-1345(00)01693-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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109
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Takayama J, Ohkohchi N, Gotoh M, Ogawa N, Nakasima N, Asakura T, Oikawa K, Kawagishi N, Watanabe M, Mizuno Y, Sakurai M, Kikuchi H, Koyamada N, Orii T, Doi H, Fujimori K, Katoh H, Satomi S, Shimaoka S. Treatment for strictures of hepatojejunostomy in living-related liver transplantation. Transplant Proc 2000; 32:2235-40. [PMID: 11120148 DOI: 10.1016/s0041-1345(00)01650-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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110
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Oikawa K, Watanabe T, Miyamoto I, Higuchi S. Determination, pharmacokinetics and protein binding of a novel tissue-type plasminogen activator, pamiteplase in human plasma. Xenobiotica 2000; 30:993-1003. [PMID: 11315107 DOI: 10.1080/00498250050200140] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
1. An enzyme-linked immunosorbent assay (ELISA) and functional bioassay to determine immunoreactive and bioactive concentrations of pamiteplase, a novel thrombolytic agent, in human plasma were developed. The ELISA and functional bioassay showed satisfactory accuracy and precision within a concentration range of 0.5-25 ng.ml(-1) and of 0.127-16.2 ng.ml(-1) respectively. 2. The pharmacokinetics of pamiteplase in healthy human subjects were evaluated using the ELISA and functional bioassay. Irrespective of the method used, plasma concentrations declined bi-exponentially. Half-lives in the beta phase were 1.25 and 0.78 h, and AUCs were 507.9 and 286.4 ng.h.ml(-1) respectively. Total clearances of pamiteplase decreased to 19 and 31% of those of the wild-type tissue-type plasminogen activator. 3. The protein binding of pamiteplase in human plasma was investigated by gel filtration chromatography. Pamiteplase formed three high molecular weight complexes with alpha2-macroglobulin, C1-esterase inhibitor and alpha2-plasmin inhibitor in human plasma. This complex formation was relatively slow, and was thought to be irreversible and covalently bounded. Furthermore, this protein binding in humans resulted in the termination of biological action.
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111
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Rochet JC, Brownie ER, Oikawa K, Hicks LD, Fraser ME, James MN, Kay CM, Bridger WA, Wolodko WT. Pig heart CoA transferase exists as two oligomeric forms separated by a large kinetic barrier. Biochemistry 2000; 39:11291-302. [PMID: 10985774 DOI: 10.1021/bi0003184] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Pig heart CoA transferase (EC 2.8.3.5) has been shown previously to adopt a homodimeric structure, in which each subunit has a molecular weight of 52 197 and consists of N- and C-domains linked by a hydrophilic linker or "hinge". Here we identify and characterize a second oligomeric form constituent in purified enzyme preparations, albeit at low concentrations. Both species catalyze the transfer of CoA with similar values for k(cat) and K(M). This second form sediments more rapidly than the homodimer under the conditions of conventional sedimentation velocity and active enzyme centrifugation. Apparent molecular weight values determined by sedimentation equilibrium and gel filtration chromatography are 4-fold greater than the subunit molecular weight, confirming that this form is a homotetramer. The subunits of both oligomeric forms are indistinguishable with respect to molecular mass, far-UV CD, intrinsic tryptophan fluorescence, and equilibrium unfolding. Dissociation of the homotetramer to the homodimer occurs very slowly in benign solutions containing high salt concentrations (0.25-2.0 M KCl). The homotetramer is fully converted to homodimer during refolding from denaturant at low protein concentrations. Disruption of the hydrophilic linker between the N- and C-domains by mutagenesis or mild proteolysis causes a decrease in the relative amount of the larger conformer. The homotetramer is stabilized by interactions involving the helical hinge region, and a substantial kinetic barrier hinders interconversion of the two oligomeric species under nondenaturing conditions.
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112
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Corbett EF, Michalak KM, Oikawa K, Johnson S, Campbell ID, Eggleton P, Kay C, Michalak M. The conformation of calreticulin is influenced by the endoplasmic reticulum luminal environment. J Biol Chem 2000; 275:27177-85. [PMID: 10842171 DOI: 10.1074/jbc.m002049200] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In order to understand the dynamics of the endoplasmic reticulum (ER) luminal environment, we investigated the role of Ca(2+), Zn(2+), and ATP on conformational changes of calreticulin. Purified calreticulin was digested with trypsin in the presence or absence of Ca(2+), Zn(2+), and ATP. At low Ca(2+) concentration (<100 micrometer), calreticulin is rapidly and fully degraded by trypsin, indicating that under these conditions the protein is in a highly trypsin-susceptible conformation. Increasing Ca(2+) concentration up to 500 micrometer or 1 mm resulted in protection of the full-length calreticulin and in generation of the 27-kDa fragment highly resistant to trypsin digestion. The 27-kDa protease-resistant core of the protein represented the NH(2)-terminal half of calreticulin and was identified by its reactivity with specific antibodies and by NH(2)-terminal amino acid sequence analysis. Ca(2+)-dependent changes in calreticulin's sensitivity to proteolysis indicate that agonist-induced fluctuation in the free ER luminal Ca(2+) concentration may affect the protein conformation and function. Trypsin digestion of calreticulin in the presence of Zn(2+) resulted in the formation of a 17-kDa central protease-resistant core in the protein corresponding to the central region of the protein, indicating that under these conditions the N- and C-domains of the protein are in an extended conformation. Here we also show that calreticulin is an ATP-binding protein but that it does not contain detectable ATPase activity. Digestion of the protein with trypsin in the presence of Mg(2+)-ATP protects the full-length protein. These results indicate that calreticulin may undergo frequent, ion-induced conformation changes, which may affect its function and its ability to interact with other proteins in the lumen of the ER.
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113
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Oikawa K, Watanabe T, Higuchi S. Comparison of drug disposition between wild-type and novel tissue-type plasminogen activator pamiteplase in rats. Drug Metab Dispos 2000; 28:1087-93. [PMID: 10950854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023] Open
Abstract
The pharmacokinetics of pamiteplase in rats was compared with the pharmacokinetics of recombinant wild-type tissue-type plasminogen activator (rwt-PA). The half-life in the beta-phase and total clearance after administration of (125)I-labeled pamiteplase ((125)I-pamiteplase) to rats were 480 and 22% of those of (125)I-labeled rwt-PA ((125)I-rwt-PA), respectively. The amount of radioactivity distributed in the liver after administration of (125)I-pamiteplase was lower than that of (125)I-rwt-PA; consequently, a possible difference in metabolism between the drugs was assessed by an integration plot and a tissue-sampling single-injection technique. Use of these two methods revealed that the hepatic clearances of both compounds accounted for almost all of the total clearance and also revealed that the hepatic clearance of (125)I-pamiteplase was markedly lower than that of (125)I-rwt-PA. Therefore, the lower distribution of pamiteplase in the liver compared with rwt-PA is thought to contribute greatly to the higher plasma concentration of pamiteplase. Additionally, the uptake of (125)I-pamiteplase in the liver was inhibited by rwt-PA, suggesting that there is a common uptake mechanism for both compounds.
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114
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Seya K, Ohkohchi N, Shibuya H, Satoh M, Oikawa K, Fukumori T, Satomi S, Motomura S. A chemiluminescent assay for hydroperoxide level of phosphatidylcholine hydroperoxide fraction purified by two Sep-Pak cartridges in biological samples. J Pharm Biomed Anal 2000; 23:515-20. [PMID: 10933545 DOI: 10.1016/s0731-7085(00)00316-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A chemiluminescent assay for hydroperoxide level of phosphatidylcholine hydroperoxide (PCOOH) fraction purified from biological samples was presented. This method utilized of two Sep-Pak cartridges. A lipid soluble fraction was isolated from each homogenized tissue or blood by Folch's method. The mixture of phosphatidylcholine (PC) and PCOOH was separated from the lipid soluble fraction by a Sep-Pak silica cartridge. A Sep-Pak tC18 cartridge made complete separation of both PCOOH and PC possible. The hydroperoxide level of PCOOH fraction was quantified by the reaction with ferrous ion using 2-methyl-6-[p-methoxyphenyl]-3,7-dihydroimidazo[1,2-a]pyrazin++ +-3-one as a chemiluminescent dye. The mixture of positional isomers, 1-hexadecanoyl-2-[9, or 10-hydroperoxyl octadecanoyl]-sn-glycero-3-phosphocholine was used as an authentic standard. The good recovery rate for authentic PCOOH of 87.1 +/- 11.6% (mean +/- S.E., n = 4) was obtained by using two Sep-Pak cartridges. Linear calibration curve was obtained in the range from 2.5 to 20 nmol, and the detection limit of the standard was 10 pmol (signal-to-noise ratio > 3). This method was applied to the investigation of the lipid peroxidation induced by reperfusion of the liver with cold preservation, mimicking liver transplantation in rats. The effect of liposome-encapsulated dichloromethylene diphosphonate (LEDD), which eliminate of Kupffer cells to prevent the generation of oxygen radicals on the lipid peroxidation, was compared with the untreated group as a control. After 1 h reperfusion at 37 degrees C the hydroperoxide level obtained the liver without preservation in the untreated group was 12.4 +/- 2.4 nmol/100 mg lipid (n = 4) and levels increased significantly by prolongation of the preservation time. On the other hand, the hydroperoxide level in the LEDD treated group did not change up to 24 h preservation. These results suggest that this improved assay for hydroperoxide level of PCOOH fraction in biological samples can be applied to investigations involving lipid peroxidation because of its simplicity and accuracy.
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115
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Oikawa K, Watanabe T, Higuchi S. Comparison of receptor-mediated endocytosis kinetics between wild-type t-PA and recombinant pamiteplase in isolated rat hepatocytes and liver cell plasma membranes. Xenobiotica 2000; 30:693-705. [PMID: 10963060 DOI: 10.1080/00498250050078002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
1. Differences in receptor-mediated endocytosis kinetics between pamiteplase, an engineered t-PA, and an unmodified rt-PA were examined using liver cell plasma membranes and isolated rat hepatocytes. 2. Whereas the binding site of pamiteplase on hepatocytes was the same as that of rt-PA, the Kd of pamiteplase was 5.1-7.7 times larger than that of rt-PA, indicating a lower affinity of pamiteplase for the t-PA receptor. 3. ke for pamiteplase measured using parenchymal cells or non-parenchymal cells was slightly smaller than that for rt-PA, whereas kon for pamiteplase were much lower than that of rt-PA, suggesting that the interaction between pamiteplase and the receptor is slower than that of rt-PA because of its structural modification. 4. Therefore, the difference in drug disposition between pamiteplase and rt-PA is mainly due to the difference in the hepatic clearance caused by a change in the interaction rate between the ligand and its cell-surface receptor.
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116
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Ichiyanagi T, Tateyama C, Oikawa K, Konishi T. Comparison of anthocyanin distribution in different blueberry sources by capillary zone electrophoresis. Biol Pharm Bull 2000; 23:492-7. [PMID: 10784434 DOI: 10.1248/bpb.23.492] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Capillary zone electrophoretic separation of blueberry anthocyanins was studied using a Na-borate buffer containing trans-1,2-diaminocyclohexane-N,N,N',N'-tetra acetic acid monohydrate (CyDTA) as the carrier buffer. The separation conditions were precisely examined using an aqueous extract of bilberry (wild type blueberry) as the separation sample which is rich in this type and amount of anthocyanins. Each separated peak was identified by comparing the mobility with that of anthocyanin standards after normalization against the mobility of malvidin 3-o-glucoside (Mv 3-Glc) added as an internal standard. As salt concentrations of the running buffer increased, the peak resolution was markedly improved over the whole range of separation, especially, among the fast moving components (petunidin 3-glucoside, cyanidin 3-glucoside and malvidin 3-galactoside). Inversely, the peak separation both between petunidin 3-glucoside and peonidin 3-glucoside, and between delphinidin 3-glucoside and petunidin 3-galactoside, respectively, were decreased. The anthocyanins were, however, successfully separated by decreasing the buffer pH. Good separation of anthocyanins was finally achieved by 30 mM Na-borate (pH 8.78) containing 7.5 mM CyDTA within 10 min. Under this separation condition, anthocyanins from different blueberry sources were analyzed. The results revealed that different blueberry sources had their own patterns of anthocyanin distribution and amounts in the extracts, thus the present method is suitable for the quality control of anthocyanin-containing food materials.
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117
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Togashi H, Shinzawa H, Matsuo T, Takeda Y, Takahashi T, Aoyama M, Oikawa K, Kamada H. Analysis of hepatic oxidative stress status by electron spin resonance spectroscopy and imaging. Free Radic Biol Med 2000; 28:846-53. [PMID: 10802214 DOI: 10.1016/s0891-5849(99)00280-4] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Real-time detection of free radicals generated within the body may contribute to clarify the pathophysiological role of free radicals in disease processes. Of the techniques available for studying the generation of free radicals in biological systems, electron spin resonance (ESR) has emerged as a powerful tool for detection and identification. This article begins with a review of spin trapping detection of oxygen-centered radicals using X-band ESR spectroscopy and then describes the detection of superoxide and hydroxyl radicals by the spin trap 5,5-dimethyl-1-pyrroline-N-oxide and ESR spectroscopy in the perfusate from isolated perfused rat livers subjected to ischemia/reperfusion. This article also reviews the current status of ESR for the in vivo detection of free radicals and in vivo imaging of exogenously administered free radicals. Moreover, we show that in vivo ESR-computed tomography with 3-carbamoyl-2,2,5, 5-tetramethylpyrrolidine-1-oxyl may be useful for noninvasive anatomical imaging and also for imaging of hepatic oxidative stress in vivo.
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118
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Togashi H, Matsuo T, Shinzawa H, Takeda Y, Shao L, Oikawa K, Kamada H, Takahashi T. Ex vivo measurement of tissue distribution of a nitroxide radical after intravenous injection and its in vivo imaging using a rapid scan ESR-CT system. Magn Reson Imaging 2000; 18:151-6. [PMID: 10722975 DOI: 10.1016/s0730-725x(99)00122-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
To establish the usefulness of ESR-CT imaging with 3-carbamoyl-2,2,5, 5-tetramethylpyrrolidine-1-oxyl (carbamoyl-PROXYL) in living animals, we investigated the tissue distribution of carbamoyl-PROXYL after i. v. injection. Ten minutes after injection of carbamoyl-PROXYL, its concentrations in the liver, spleen, kidney, and plasma were higher than those in the small intestine and stomach. However, the inter-organ differences in concentrations were not striking. We selected the liver as a representative organ and attempted to measure the concentration of carbamoyl-PROXYL in it after washing out all of the blood by in situ perfusion with saline. The ESR spectrum of the liver homogenate after complete blood washout revealed that the concentration of carbamoyl-PROXYL was significantly reduced. Thus, at this time, carbamoyl-PROXYL was distributed predominantly in the plasma and/or loosely attached to the surfaces of cells. We obtained high-quality ESR-CT images of the murine abdomen at a measurement time of 40 s and found that a high-intensity area of carbamoyl-PROXYL appeared in the liver and kidneys, indicating an abundant blood circulation. Although the organ specificity of carbamoyl-PROXYL was weak, we consider that ESR-CT imaging with carbamoyl-PROXYL will be a powerful new tool for non-invasive anatomic analysis of the liver and the kidneys.
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119
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Narayanaswami V, Yamauchi Y, Weers PM, Maekawa H, Sato R, Tsuchida K, Oikawa K, Kay CM, Ryan RO. Spectroscopic characterization of the conformational adaptability of Bombyx mori apolipophorin III. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:728-36. [PMID: 10651809 DOI: 10.1046/j.1432-1327.2000.01050.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Apolipophorin III (apoLp-III) from the silkmoth, Bombyx mori, has been over-expressed in Escherichia coli, purified and characterized. Far-UV CD spectroscopic analysis revealed 65% alpha-helix secondary structure. Near-UV CD spectra obtained in buffer or complexed with dimyristoylglycerophosphocholine (DMPC), provided evidence that apoLp-III alpha-helices reorient upon interaction with lipid, indicative of a protein conformational change. In guanidine hydrochloride (GdnHCl) denaturation studies, a transition midpoint of 0.33 M was observed, corresponding to a DeltaGDH2O = 2.46 kcal. mol-1. Fluorescence studies of the sole tryptophan residue (Trp40) in apoLp-III revealed an emission lambdamax = 327 nm. Compared to free tryptophan, Stern-Volmer constants (KSV) for acrylamide and KI quenching of Trp40 fluorescence were decreased by 20-fold and sevenfold, respectively. In studies of apoLp-III-DMPC disc complexes, far-UV CD spectroscopy revealed an increase in alpha-helix content to approximately 85% and a ninefold increase in the GdnHCl-induced denaturation transition midpoint to 3 M. In studies of lipid interaction, apoLp-III was shown to disrupt both negatively charged and zwitterionic phospholipid bilayer vesicles, transforming them into discoidal complexes. Characterization of apoLp-III-DMPC discs, using 5-doxyl or 12-doxyl stearic acid as lipid-based quenching agents, revealed that Trp40 localizes near the phospholipid polar head groups. KSV values for acrylamide and KI quenching of intrinsic fluorescence of apoLp-III-DMPC discs indicate that Trp40 is embedded in the lipid milieu, with little or no accessibility to the aqueous quenchers. Given the large amount of alpha-helix in apoLp-III, the data presented support a model in which amphipathic alpha-helical segments are stabilized by helix-helix interactions and lipid association induces a protein conformational change which results in substitution of helix-helix interactions for helix-lipid contacts.
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Ghetu AF, Gubbins MJ, Oikawa K, Kay CM, Frost LS, Glover JN. The FinO repressor of bacterial conjugation contains two RNA binding regions. Biochemistry 1999; 38:14036-44. [PMID: 10529250 DOI: 10.1021/bi9911482] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Conjugative transfer of F-like plasmids in Escherichia coli is repressed by a plasmid-encoded protein, FinO. FinO blocks the translation of TraJ, a positive activator of transcription of genes required for conjugation. FinO binds a traJ antisense RNA, FinP, thereby protecting it from degradation, and catalyzes FinP-traJ mRNA hybridization. Interactions between these two RNAs are predicted to block the traJ ribosomal binding site. In this paper, we use limited proteolysis, circular dichroism spectroscopy, and an electrophoretic mobility shift assay to map the regions within FinO that are required for interactions with RNA. Our results show that FinO is largely helical, binds to its highest affinity binding site within FinP as a monomer, and contains two distinct RNA binding regions, one of which is localized between residues 26 and 61, and a second which is localized between residues 62 and 186.
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Oikawa K, Sumi SI, Ishida K. The effects of addition of deoxidation elements on the morphology of (Mn,Cr)S inclusions in stainless steel. ACTA ACUST UNITED AC 1999. [DOI: 10.1361/105497199770335749] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Ohkohchi N, Endoh T, Oikawa K, Seya K, Satomi S. Fragility of the electron transport chain and superoxide generation in mitochondria of the liver graft after cold ischemia. Transplantation 1999; 67:1173-7. [PMID: 10232570 DOI: 10.1097/00007890-199904270-00015] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND After cold ischemia, electrons transferred in the electron transport chain may leak out of the mitochondria in proportion to the deterioration of mitochondrial oxidative phosphorylation. This seems to be one major cause of the lipid peroxidation that occurs mainly in the hepatocytes at reperfusion in liver transplantation. To examine this hypothesis, we investigated superoxide generation and the amount of oxidative phosphorylation in the mitochondria isolated from rat livers after cold preservation. METHODS Rat liver was preserved in University of Wisconsin solution at 4 degrees C for 24 hr. The mitochondrial fraction was prepared, and the amount of ATP synthesis and superoxide generation was investigated. Superoxide generation in the electron transport chain of submitochondrial particles was also measured by a chemiluminescence recorder. RESULTS The amount of ATP synthesis was significantly decreased after 12 hr of cold preservation. In the whole mitochondria, superoxide production in the presence of succinate was approximately 1/2000 to 1/3000 less than that observed in the submitochondrial particles at any determination point, and superoxide production was not affected by cold preservation. In the presence of antimycin A, superoxide production in the mitochondria after 18 hr of preservation increased significantly. CONCLUSION These results indicate that the electron transfer in the complex III of the mitochondrial membrane becomes leaky after long periods of cold ischemia, but that leakage of superoxide anion did not increase, although the mitochondrial respiratory phosphorylation was deteriorated. We conclude that superoxide through the mitochondrial membrane cannot cause lipid peroxidation in hepatocytes at reperfusion even after a long period of cold ischemia.
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Corbett EF, Oikawa K, Francois P, Tessier DC, Kay C, Bergeron JJ, Thomas DY, Krause KH, Michalak M. Ca2+ regulation of interactions between endoplasmic reticulum chaperones. J Biol Chem 1999; 274:6203-11. [PMID: 10037706 DOI: 10.1074/jbc.274.10.6203] [Citation(s) in RCA: 151] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Casade Blue (CB), a fluorescent dye, was used to investigate the dynamics of interactions between endoplasmic reticulum (ER) lumenal chaperones including calreticulin, protein disulfide isomerase (PDI), and ERp57. PDI and ERp57 were labeled with CB, and subsequently, we show that the fluorescence intensity of the CB-conjugated proteins changes upon exposure to microenvironments of a different polarity. CD analysis of the purified proteins revealed that changes in the fluorescence intensity of CB-ERp57 and CB-PDI correspond to conformational changes in the proteins. Using this technique we demonstrate that PDI interacts with calreticulin at low Ca2+ concentration (below 100 microM), whereas the protein complex dissociates at >400 microM Ca2+. These are the Ca2+ concentrations reminiscent of Ca2+ levels found in empty or full ER Ca2+ stores. The N-domain of calreticulin interacts with PDI, but Ca2+ binding to the C-domain of the protein is responsible for Ca2+ sensitivity of the interaction. ERp57 also interacts with calreticulin through the N-domain of the protein. Initial interaction between these proteins is Ca2+-independent, but it is modulated by Ca2+ binding to the C-domain of calreticulin. We conclude that changes in ER lumenal Ca2+ concentration may be responsible for the regulation of protein-protein interactions. Calreticulin may play a role of Ca2+ "sensor" for ER chaperones via regulation of Ca2+-dependent formation and maintenance of structural and functional complexes between different proteins involved in a variety of steps during protein synthesis, folding, and post-translational modification.
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Ohkohchi N, Shibuya H, Tsukamoto S, Sakurada M, Oikawa K, Terashima T, Satomi S. Kupffer's cells modulate neutrophile activity by superoxide anion and tumor necrosis factor-delta in reperfusion injury of liver transplantation-mechanisms of radical generation and reperfusion injury after cold ischemia. Transplant Proc 1999; 31:1055-8. [PMID: 10083472 DOI: 10.1016/s0041-1345(98)01902-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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Kishida H, Saitoh T, Oikawa K, Honma H, Kusama Y. Negative U-wave as a predictor of antihypertensive treatment effect on regression of echocardiographic hypertrophy in hypertensive patients. JAPANESE HEART JOURNAL 1999; 40:31-44. [PMID: 10370395 DOI: 10.1536/jhj.40.31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
To clarify the mechanism and the predictors of the reduction in left ventricular mass (LVM) induced by antihypertensive drugs, forty hypertensive patients were classified according to the presence of left ventricular hypertrophy (LVH) as a defined by echocardiographic LVM findings (LVH group: 27 patients, non-LVH group: 13 patients) and according to the presence of negative U-waves (NU) (NU group: 10 patients, non-NU group: 30 patients). Negative U-waves appeared in the LVH group only (10 of 27 patients). The hemodynamic determinants were investigated as a mechanism of LVM reduction in 38 of these patients who were treated for 2 years with antihypertensive drugs. In the LVH group, thickness of interventricular septum (IVST), posterior wall thickness (PWT) and LVM increased significantly compared to the non-LVH group. In the NU group, the left ventricular end-diastolic dimension (LVDD) was significantly larger and the relative wall thickness was significantly smaller compared to the non-NU group in the LVH group, with no difference in LVM between the two groups. Negative U-waves disappeared in all cases after treatment. Significant decreases in LVDD and LV wall thickness were observed in the NU group and significant decrease in LV wall thickness in the non-NU group. LVM index was reduced by 24.0% in the NU group and 9.5% in the non-NU group. The disappearance of negative U-waves was an independent predictor of the reduction of LVH.
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