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Y Shishido

Publications and source records attributed to Y Shishido.

At least 19 recordsLinked to original sources
PubMed2001

CD9 amino acids critical for upregulation of diphtheria toxin binding.

CD9 associates with a diphtheria toxin receptor (DTR) that is identical to the membrane-anchored form of heparin-binding EGF-like growth factor. We determined the region of CD9 important for upregulation activity. Human and monkey CD9 upregulates DT binding activity of DTR, while mouse CD9 has no upregulation activity. Transfection of chimeric constructs comprising monkey and mouse CD9s showed that the human sequence between Ala156 and Asp183 is essential for the upregulation activity. Studies of mutants, replacing a single amino acid within the region between Ala156 and Asp183 of monkey CD9 with the corresponding amino acid residue in mouse CD9, revealed that substitution of Gly158 is critical for the reduction of the upregulation activity and secondly for the substitution of Val159 and Thr175. These three amino acid residues were deduced to be located on the head domain of the second extracellular loop, suggesting that interactions of CD9 with DTR or DT at the domain containing these three amino acids were important for the upregulation of DT binding.

Amino Acid Sequence↗
PubMed1999

Effects of prolyl endopeptidase inhibitors and neuropeptides on delayed neuronal death in rats.

We investigated the effects of the prolyl endopeptidase inhibitors 1-[1-(Benzyloxycarbonyl)-L-prolyl]prolinal (Z-Pro-Prolinal) and N-benzyloxycarbonyl-thioprolyl-thioprolinal-dimethylaceta l (ZTTA) on delayed neuronal death induced by four-vessel-occlusion transient ischemia in rats. We also examined the effects of [pGlu4, Cyt6, ArgS]vasopressin (vasopressin-(4-9)) and thyrotropin-releasing hormone (TRH) on the delayed neuronal death. Furthermore, we investigated the role of vasopressin receptors in the effects of vasopressin and prolyl endopeptidase inhibitors. Z-Pro-Prolinal, vasopressin-(4-9) and TRH protected pyramidal cells in the CA1 subfield of the rat hippocampus from delayed neuronal death after 10-min ischemia. The effect of vasopressin-(4-9) was abolished by vasopressin receptor antagonists. The effect of Z-Pro-Prolinal was also abrogated by the antagonists. These results suggest that the neuroprotective effect of prolyl endopeptidase inhibitors is mediated by neuropeptides such as [Arg8]vasopressin and TRH, and indicate the involvement of vasopressin receptors in the neuroprotective effect of vasopressin-(4-9) and prolyl endopeptidase inhibitors.

Animals↗
PubMed1999

Effects of arginine-vasopressin fragment 4-9 on rodent cholinergic systems.

Arginine-vasopressin fragment 4-9 (AVP4-9) has been demonstrated in animal studies to facilitate learning and memory. To clarify the mechanisms of this facilitation, we focused on the effects of AVP4-9 on rodent cholinergic systems. AVP4-9 (0.1 microM) enhanced the basal and the high-potassium-evoked acetylcholine (ACh) release from rat hippocampal slices (122.4 and 120.0% of control, respectively) in the presence of 1.3 mM calcium (physiological level) at 60 min after the incubation at 37 degrees C. The AVP4-9-stimulated basal ACh release was inhibited by a V1-selective antagonist ([(beta-mercapto-beta,beta-cyclopentamethylene propionic acid)1, O-methyl-Tyr2, Arg8] vasopressin), but not by a V2-selective antagonist ([adamantaneacetyl1, O-ethyl-D-Tyr2, Val4, aminobutyryl6, Arg8,9]-vasopressin). In addition, AVP4-9 did not affect the basal ACh release under the calcium-free condition at 37 degrees C or in the presence of 1.3 mM calcium at 4 degrees C. However, AVP4-9 facilitated the passive-avoidance response of scopolamine (a cholinergic blocker)-induced memory-deficient mice. These findings demonstrate that AVP4-9 stimulates ACh release via mediation by V1-like vasopressin receptors, and shows dependence on calcium ion and temperature. The results also suggest that the mechanism of the facilitative effects of AVP4-9 on learning and memory consist of the observed stimulation of cholinergic systems and other parallel pathways that would not be inhibited by cholinergic blocking.

Acetylcholine↗
PubMed1999

Peritoneal dialysis--associated peritonitis caused by gram-negative bacteria: characteristics similar to spontaneous bacterial peritonitis?

The aim of the study was to investigate the characteristics of PD-related peritonitis caused by gram-negative bacteria (GNP). We retrospectively studied the medical records of 164 patients (114 males, 50 females; mean age 46 +/- 15 years) who continued PD beyond 5 months between 1984 and 1998. The average observation time was 40 +/- 28 months (total of 6609 patient-months). A total of 166 episodes of peritonitis occurred during that time (mean incidence: 1 episode/40 patient-months). Of these, 35 were GNPs, and GNP incidence stayed almost constant over time. Most GNP patients (63%) recovered without complication with an average of 14 days' antibiotic treatment. In only 4 cases was PD abandoned. Clinical features of GNP were similar to those of spontaneous bacterial peritonitis (SBP). The unchanged incidence of GNP over time with advanced connection devices suggests that there are important mechanisms promoting micro-organisms of endogenous origin into the peritoneal cavity in PD patients.

Adolescent↗
PubMed1997

Structure-function analysis of the diphtheria toxin receptor toxin binding site by site-directed mutagenesis.

Diphtheria toxin (DT) binds to the epidermal growth factor (EGF)-like domain of human membrane-anchored heparin-binding EGF-like growth factor (proHB-EGF), the human DT receptor (DTR). DT does not bind to mouse proHB-EGF because of amino acid substitutions within the EGF-like domain. We made 10 independent mutants, replacing a single amino acid within the EGF-like domain of human DTR/proHB-EGF with the corresponding amino acid residue in mouse proHB-EGF. The mutant proteins were transiently expressed in mouse L cells either expressing or not expressing DRAP27/CD9, and DT binding was measured. DT binding activity of GST fusion proteins containing the mutated EGF-like domain was also determined by a cell-free binding assay. The largest effect was seen with E141H, and second largest effects were seen with F115Y and L127F in all of the assay systems. We conclude that Phe115, Leu127, and Glu141 are critical amino acid residues for DT binding. A computer model of the tertiary structure of the EGF-like domain of human DTR/proHB-EGF was made. The model predicts that three amino acid residues critical for DT binding activity, Phe115, Leu127, and Glu141, are all located on the same face of the EGF-like domain, suggesting that this face of DTR/proHB-EGF interacts with the receptor-binding domain of DT.

Amino Acid Sequence↗
PubMed1997

Immune system-related CD9 is expressed in mouse central nervous system myelin at a very late stage of myelination.

CD9 is a tetra-membrane-spanning glycoprotein involved in cell adhesion, migration, and proliferation in both the immune and the immature nervous system. In this study, CD9 expression was detected in myelin of mouse brain, starting at postnatal day 16. The amount of CD9 protein continuously increased with age and persisted in the adult brain. It appeared later than myelin proteolipid protein (PLP), a typical late myelin marker. Mature oligodendrocytes were abundant in CD9, although it was also detected in astrocytes and microglial cells in vitro. CD9 appeared at the end of the myelination process and was localized along the outermost membrane of compact myelin. CD9 is known to associate with integrins, which are candidate receptors for extracellular matrix and transmit extracellular signals into the cells. Taken together, CD9 at the surface of central nervous system (CNS) mature myelin may have a unique function to facilitate signal transduction and enhance myelin membrane adhesion to extracellular matrices at very late stages of development.

Animals↗
PubMed1997

Effects of oral administration of soybean lecithin transphosphatidylated phosphatidylserine on impaired learning of passive avoidance in mice.

Soybean lecithin transphosphatidylated phosphatidylserine (SB-tPS) was investigated for its effect on the impaired learning of a passive avoidance task by mice induced by scopolamine or cycloheximide. SB-tPS (240, 360, 480 mg/kg) administered orally significantly prolonged the step-through latency shortened by scopolamine. SB-tPS (240 mg/kg) administered orally also prolonged the step-through latency shortened by cycloheximide. These results suggest that the effect of SB-tPS on the impaired learning behavior may be related not only to the cholinergic system but also the serotonergic system.

Administration, Oral↗
PubMed1997

Assembly of JC virus-like particles in COS7 cells.

JC virus lacks an appropriate cell line to support virus replication. The establishment of a JC pseudovirus assembly system could play an alternative role for a virus culture system. COS7 cells and a transfer vector, pcDL-SR alpha 296, were used to express JC viral structural genes. VP231-SR alpha, which encodes VP2/VP3 and VP1, but lacks 137 bp of the 5'-terminus of agnogene, showed both efficient nuclear migration and quantitative expression of the major capsid protein VP1. JC pseudovirus assembly was observed in the nucleus of VP231-SR alpha transfected cells. Evidence of JC pseudovirus assembly is presented. The further utilization of this system, which includes a study for the viral morphogenesis, serological diagnosis, as well as the potential application for gene transfer vector, is discussed.

Animals↗
PubMed1997

LDH isoenzyme of the dialysate in noninfected PD patients.

We wished to investigate lactic dehydrogenase (LDH) and its isoenzymes in the dialysate of peritoneal dialysis (PD) patients under noninfected conditions. Twenty-seven continuous ambulatory peritoneal dialysis (CAPD) patients (20 males, 7 females; mean age 53 years; average duration of CAPD 29 months) were studied. Overnight dialysate and blood samples were collected. LDH activities, isoenzymes, glucose, creatinine of both specimens, and cancer antigen 125 (CA125) of the dialysate were determined. Serum and dialysate LDH was 470 +/- 163 and 10 +/- 4 U/L, respectively. Percentages of LDH1, LDH2, LDH3, LDH4, and LDH5 were 29 +/- 5, 37 +/- 4, 20 +/- 3, 9 +/- 4, and 6 +/- 2 (%) in the serum, 21 +/- 5, 30 +/- 5, 23 +/- 6, 16 +/- 4, and 8 +/- 3 (%) in the dialysate, respectively. There was no significant relationship between the serum and dialysate LDHs. There were no correlations between dialysate LDH, patient's age, duration of CAPD, peritoneal transport properties, and dialysate CA125. Although it was still difficult to determine the origin of dialysate LDH, a predominance of LDH5 was not observed in noninfected stable patients. Dialysate LDH activities were low, and the isoenzyme patterns were similar to those of the serum. Alteration of the isoenzyme patterns may suggest unfavorable events, such as infection, in the peritoneal cavity.

CA-125 Antigen↗
PubMed1996

ZTTA, a postproline cleaving enzyme inhibitor, improves cerebral ischemia-induced deficits in a three-panel runway task in rats.

We investigated the effect of N-benzyloxycarbonyl-thioprolyl-thioprolinal-dimethylaceta l (ZTTA), a novel postproline cleaving enzyme (prolyl endopeptidase, PPCE) inhibitor, on the in vitro activity of rat brain PPCE and memory impairment induced by cerebral ischemia. ZTTA noncompetitively inhibited rat brain PPCE (ki = 2.9 microM). Cerebral ischemia for 5 min increased the number of errors in a working memory task with a three-panel runway paradigm. ZTTA at 6 mg/kg, administered immediately after blood flow reperfusion, significantly reduced the increase in working memory errors expected to occur 24 h after 5 min of ischemia. The antiamnesic action of ZTTA may be ascribable to a neuroprotective effect on the central nervous system due to some neuropeptides that are substrates of PPCE in the brain.

Animals↗
PubMed1996

[Assembly of JC virus pseudovirus particles by recombinant DNA in COS7 cells].

JS virus lacks an appropriate cell line to support virus replication. The establishment of a JC pseudovirus assembly system would play an alternative role for a virus culture system. COS7 cells and a transfer vector, pcDL-SR alpha 296 were used to express JC viral structural genes. VP231-SR alpha, which encodes VP2/VP3 and VP1, but lacks 137bp of the 5'-terminus of agnogene, showed both efficient nuclear migration and quantitative expression of the major capsid protein VP1. JC pseudovirus assembly was observed in the nucleus of VP231-SR alpha transfected cells. In this study, evidence for JC pseudovirus assembly is presented. The further utilization of this system, which includes a study for the viral morphogenesis and serological diagnosis, are discussed.

Cell Line, Transformed↗
PubMed1995

Heparin-like molecules on the cell surface potentiate binding of diphtheria toxin to the diphtheria toxin receptor/membrane-anchored heparin-binding epidermal growth factor-like growth factor.

Diphtheria toxin receptor (DTR), which is identical to the membrane-anchored form of heparin-binding EGF-like growth factor (proHB-EGF), has a high affinity for heparin. We studied the effect of heparin-like molecules on the binding of diphtheria toxin (DT) to DTR/proHB-EGF. Mutant Chinese hamster ovary (CHO) cells deficient in heparan sulfate (HS) proteoglycans were about 15 times less sensitive to DT than wild type CHO-K1 cells. When free heparan sulfate or heparin was added to the culture medium, DT sensitivity of the mutant cells was fully restored. Studies of binding of 125I-labeled DT to HS-deficient CHO cells transfected with human DTR/proHB-EGF cDNA indicated that the increased sensitivity to DT after addition of heparin is due to increased binding of DT to cells. Vero cells display a relatively large amount of heparan sulfate residues compared to CHO-K1 cells or L cells. Enhancement of DT binding by the addition of heparin was also observed with CHO-K1 cells and L cells that had been transfected with human DTR/proHB-EGF cDNA, but the degree of enhancement was less than that observed with the HS-deficient CHO cells. Addition of heparin did not affect DT binding or DT sensitivity of Vero cells. Heparin-dependent binding was observed when intact Vero cells were treated with heparitinase or when the cell membrane was solubilized with a neutral detergent. Scatchard plot analysis for the binding of DT to a recombinant HB-EGF in vitro and to L cells expressing human DTR/proHB-EGF revealed that heparin increases the affinity of DTR/proHB-EGF for DT but does not change the number of binding sites. Although DRAP27/CD9 is known to enhance DT binding to DTR/proHB-EGF, the results indicate that heparin and DRAP27/CD9 increase DT binding by independent mechanisms. Thus, heparin-like molecules, probably in the form of heparan sulfate proteoglycan on the cell surface, are a third factor required for maximal DT binding activity of cells.

Animals↗
PubMed1994

Facilitatory effect of vasopressin on the ischemic decrease of the CA1 presynaptic fiber spikes in rat hippocampal slices.

We investigated the effects of vasopressin-related neuropeptides on the hypoxia/hypoglycemia (ischemia)-induced decrease of the CA1 presynaptic potential elicited by stimulation of Schaffer collaterals in rat hippocampal slices. Treatment with arginine-vasopressin (AVP) potentiated the ischemic decrease of the CA1 presynaptic potential. In contrast, a V1 receptor antagonist produced a dose-dependent neuroprotective effect, whereas a V2 receptor antagonist had no effect. The AVP-induced decrease of the CA1 presynaptic potential was completely blocked by simultaneous application of the V1 receptor antagonist. Because AVP4-9 is regarded as the major proteolytic product of AVP in the rat brain, we examined its effect on the ischemic decrease of the CA1 presynaptic potential. Treatment with AVP4-9 produced a more marked reduction of the potential than treatment with AVP itself. The present study demonstrates that stimulation of the V1 receptor has a detrimental effect on the development of ischemic damage whereas V1 receptor blockade has a neuroprotective effect, suggesting that AVP may potentiate ischemic neuronal deficits via V1 receptor stimulation.

Animals↗
PubMed1994

Fibrin-specific fibrinolysis induced by recombinant staphylokinase.

We compared the thrombolytic properties of recombinant staphylokinase (SAK) with those of streptokinase (SK), a tissue-type plasminogen activator (t-PA) and a urokinase-type plasminogen activator (u-PA) in the jugular vein thrombosis model in the rabbit in vivo and a circulating human plasma system in vitro. 50% thrombolysis was observed at 360 min after intravenous infusion into rabbits of 150 micrograms/kg of SAK or 500 micrograms/kg of t-PA, respectively. And the fibrinogen level in the blood was not affected by either agent. 50% clot lysis in vitro was observed at 120 min with 1.8 micrograms/ml of SAK, 22.1 micrograms/ml of SK, 2.1 micrograms/ml of t-PA, or 4.7 micrograms/ml of u-PA, respectively. All the plasminogen activators with the exception of SAK decreased the residual fibrinogen level in the circulating plasma at their moderate concentration for clot lysis. SAK had less influence on the plasminogen and alpha 2-plasmin inhibitor (alpha 2-antiplasmin) levels than the other plasminogen activators. These findings suggest that SAK is a potent fibrin-specific thrombolytic agent.

Animals↗
PubMed1994

Involvement of protease inhibitors in staphylokinase-induced fibrin-specific fibrinolysis.

We compared the fibrinolytic properties of recombinant staphylokinase (SAK), a fibrin-specific plasminogen activator, with those of streptokinase and tissue-type plasminogen activator (t-PA) by means of the amidolytic method. We also investigated the involvement of alpha 2-macroglobulin, C1-inactivator and alpha 1-antitrypsin in SAK-induced fibrin-specific fibrinolysis. Both SAK and t-PA activated plasminogen efficiently in the presence of fibrin in human plasma. Although t-PA activated plasminogen dependently on fibrin in the reconstituted plasma system, SAK activated plasminogen independently of fibrin without alpha 2-plasmin inhibitor (alpha 2-antiplasmin, alpha 2-PI). These findings suggest that fibrin and alpha 2-PI play important roles in plasminogen activation by SAK but not by t-PA. Furthermore, protease inhibitors such as alpha 2-PI, alpha 2-macroglobulin, C1-inactivator and alpha 1-antitrypsin inhibited plasminogen activation by SAK and the inhibitory actions of these protease inhibitors disappeared in the presence of fibrin. This shows that alpha 2-macroglobulin, C1-inactivator and alpha 1-antitrypsin, other than alpha 2-PI, contribute to the fibrin-specificity of SAK.

Amino Acid Sequence↗