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T Akira

Publications and source records attributed to T Akira.

16 recordsLinked to original sources
PubMed1999

Prostaglandin E1 transported into cells blocks the apoptotic signals induced by nerve growth factor deprivation.

Neuronal apoptosis in rat pheochromocytoma PC12 cells, which was confirmed by TUNEL (terminal transferase-mediated dUTP-biotin nick end-labeling) staining and detection of chromatin condensation, appeared within 8 h after nerve growth factor (NGF) deprivation. Prostaglandin (PG) E1 (10(-7)-10(6) M) reduced the incidence of apoptotic cell death in PC12 cells. The genes encoding PG transporter specific to prostaglandins such as PGE2 or PGF2alpha were expressed in the cell lines as shown by RT-PCR. Bromcresol green, an inhibitor of PG transporter, reversed the antiapoptotic effect of PGE1. Moreover, treatment of PC12 cells with an antisense oligonucleotide corresponding to PG transporter cDNA also blocked the inhibitory effects of PGE1 on apoptotic cell death. In addition, PGE1 counteracted the increased activities of stress-activated protein kinase/cJun N-terminal kinase within 1-2 h after NGF deprivation in PC12 cells. These results indicated that the antiapoptotic effect of PGE1 in NGF-deprived PC12 cells was achieved by inhibitory signals following uptake into neurons through the PG transporter.

Alprostadil↗
PubMed1998

Study of hepatitis C virus genotype in Guizhou area of southwestern China.

OBJECTIVE: To determine the concordance in various hepatitis C (HCV) genotyping methods and to investigate the distribution of HCV genotypes in Guizhou area of Southwest China. METHODS: Serum samples from 206 patients (100 with chronic hepatitis and 106 with hemopathy) were detected for antibody of HCV by second generation enzyme-labelled immunosorbent assay (ELISA). Thirty-five anti-HCV positive samples were detected for HCV RNA by RT-polymerase chain reaction (PCR) and 30 HCV RNA positive samples were determined for their genotypes by three various genotyping methods [PCR with type-specific primers at the core region (primer-set), slot-blot hybridization with type-specific probes at NS5B region (blotting) and the restric fragment length polymorphism analysis of PCR products of 5' NC region (RFLP)]. Ten samples with the known genotype were analysed by the direct sequencing. RESULTS: Of 30 samples with positive HCV RNA, the types of 22 could be classified by three methods, and the genotypes determined by various methods had complete concordance. The types of 6 samples could be classified by two methods and 5 had agreement subtypes. The types of two samples could be classified only by RFLP. Overall, 27 (90.0%) had subtype 1b infection and 3 (10.0%) had subtype 2a infection. The nucleotide sequence of 8 samples with subtype 1b and one with subtype 2a were analysed by the direct sequencing. The subtypes determined by sequence analysis were in complete concordance with those decided by various genotyping methods. CONCLUSIONS: Subtype 1b is the predominent HCV genotype in Guizhou area, while subtype 2a is less common. There was a good concordance with the genotyping results obtained by various HCV genotyping methods.

Antibodies, Viral↗
PubMed1997

Molecular cloning and expression of a rat cDNA encoding 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/IMP cyclohydrolase.

The cDNA of a 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/IMP cyclohydrolase (AICARFT/IMPCHase) was isolated from rat liver RNA by reverse transcription and the polymerase chain reaction (PCR). The rat AICARFT/IMPCHase cDNA included 1928 bp containing a coding region of 1779 bp for a 592-amino acid polypeptide (Mr = 64 200). Rat and human AICARFT/IMPCHase cDNAs show 84 and 91% homology at the nucleotide and amino acid sequence level, respectively. The protein produced by the rat cDNA using pET-expression system catalysed the penultimate and final steps of de novo purine biosynthesis. Northern analysis identified a 2.8-kb AICARFT/IMPCHase mRNA and the level of the AICARFT/IMPCHase transcripts increased markedly at 24 h after partial (70%) hepatectomy.

Amino Acid Sequence↗
PubMed1997

Expression of prostaglandin EP2 receptor mRNA in the rat spinal cord.

RT-PCR and an in situ hybridization analyses demonstrated expression of prostaglandin EP2 receptor mRNA in the subfield of the dorsal horn of the rat spinal cord. The intensive signals from the cells labeled with digoxigenin-11-dUTP were scattered through this region and they corresponded to neurons. EP2 receptor-mediated signal transduction is expected to play roles in modulating some neuronal functions such as transmission of nociceptive reaction or motor reflex.

Animals↗
PubMed1997

Prostaglandin E1 prevents apoptotic cell death in superficial dorsal horn of rat spinal cord.

Neuronal degeneration, distinguished morphologically and biochemically from necrosis, was induced in the dorsal horn of the lumbar spinal cord by chronic constriction of the sciatic nerve in rats. Neuronal apoptosis in the territory of the spinal cord which receives afferent excitatory inputs from the sciatic nerve was confirmed by TUNEL-staining and electrophoresis of genomic DNA. The morphological changes including the appearance of dark neurones, as identified by toluidine-blue staining, were almost completely blocked by 10 microg/kg of the prostaglandin E (EP) receptor agonist lipo-PGE1, incorporating PGE1 in lipid microspheres for chemical stability and targeted delivery, but not by 10 microg/kg of carbacyclin a prostacyclin (IP) receptor agonist. Lipo-PGE1 also blocked the "ladder type" fragmentation of genomic DNA extracted from tissue in the affected area of the spinal cord. Since the regional blood flow in the subfield of the spinal cord was neither influenced by the chronic injury nor by application of the vasodilative prostaglandin, the effect of lipo-PGE1 must have been achieved via another mechanism. These results demonstrate that the neuronal apoptosis in spinal cord induced by sciatic constriction injury is more effectively inhibited by the EP receptor agonist PGE1 than by the IP receptor agonist carbacyclin.

Alprostadil↗
PubMed1997

AE0047-mediated calcium channel blocking in vascular smooth muscles.

1. This experiment was designed to pharmacologically characterize a novel calcium channel blocker, AE0047. 2. After 1-hr treatment with each drug (10(-6) M), K(+)-induced contraction in rat aortic strip was clearly depressed by nifedipine and manidipine and slightly depressed by AE0047. After a wash out of the preparation in drug-free medium, the inhibition of K(+)-induced contraction by nifedipine or manidipine was abolished or unchanged, respectively. In contrast, AE0047-produced inhibition was reinforced with time after removal of the drug. 3. A cell membrane depolarization-induced 45Ca uptake into tissue was depressed completely by nifedipine, but, if it was washed out, merely 20% inhibition of control remained. AE0047-produced inhibition became prominent after drug removal. Manidipine did not have the same inhibitory effect after wash out. 4. A receptor-binding study indicated that affinity of AE0047 and manidipine for the dihydropyridine-sensitive Ca channel receptor was lower than that of nifedipine. AE0047, unlike nifedipine and manidipine, inhibited [3H]PN200-110 binding more strongly when a 4-hr preincubation was used than without extended incubation. 5. The drug molecule of AE0047 was highly partitioned into the lipid bilayer of the synaptosome in canine cerebral cortices. In the synaptic membrane and liposomes, both prepared from canine cerebral cortices, the respective partition coefficients of the drug were 6997 +/- 2309 and 422 +/- 28 against 1395 +/- 161 and 24 +/- 2 of nitrendipine. 6. AE0047 showed slower onset of inhibition against K(+)-induced contraction and enhanced Ca influx compared with manidipine and nifedipine. These results may suggest that AE0047 requires a long period of time to occupy the dihydropyridine-sensitive sites within the Ca channel, which was detected by decreased specific [3H]PN200-110 binding, and to inhibit K(+)-induced Ca influx into rat aorta.

Animals↗
PubMed1997

[SG-210].

Explore the source record for details and available documents.

Aldehyde Reductase↗
PubMed1996

Antithrombin III prevents renal dysfunction and hypertension induced by enhanced intravascular coagulation in pregnant rats: pharmacological confirmation of the benefits of treatment with antithrombin III in preeclampsia.

We tested the hypothesis that enhanced intravascular coagulation in pregnancy could produce clinical symptoms similar to those of preeclampsia, such as hypertension, proteinuria, and edema. Having confirmed this, we then examined whether the pathological changes caused by intravascular coagulation could be suppressed by administration of antithrombin III (AT III), an endogenous inhibitor active to thrombin and factor X a. Intravascular coagulation was induced in Wistar rats on day 16-20 of pregnancy by 1-h arterial infusion of tissue thromboplastin (TP) through the left ventricle of the heart. One hour after the end of the infusion period, organ blood flows were measured by the radioactive ((57)Co-labeled) microsphere method, and fibrin deposition in organs was measured by radiolabeling with [(125)I] fibrinogen injected before TP infusion. Infusion of TP produced fibrin deposition in the kidney, lung, and liver, but not in the myometrium and placenta, as well as an 80% decrease in renal blood flow (RBF), with oliguria and proteinuria. TP also caused an increase in blood pressure (BP) accompanied by an increase in plasma renin activity (PRA), both of which were suppressed by bilateral nephrectomy before TP infusion. The prophylactic administration of AT III concentrates (60 or 300 U/kg intravenously (i.v.), followed by infusion of 30 or 150 U/kg/2 h, respectively) prevented all pathological changes in a dose-dependent manner. AT III increased placental blood flow regardless of the state of coagulation. These findings suggest that intravascular coagulation plays a significant part in the pathophysiology of preeclampsia and that AT III concentrates may have therapeutic potential in the treatment of this condition.

Animals↗
PubMed1996

Antithrombin III prevents blood pressure elevation and proteinuria induced by high salt intake in pregnant stroke-prone spontaneously hypertensive rats.

In pregnant stroke-prone spontaneously hypertensive rats, salt-loading causes symptoms similar to those of human preeclampsia, such as hypertension and proteinuria. To seek evidence of the therapeutic potential in preeclampsia of antithrombin III (AT III), which is a serine protease inhibitor active on various enzymes of the coagulation cascade, we examined the effect of consecutive treatment with AT III on hypertension and proteinuria in this animal model. Salt-loading (2% NaCl diet) caused a significant elevation of systolic blood pressure on day 15-17 and of urinary protein excretion on day 17-19 of gestation, as compared with animals fed a normal diet. AT III, administered i.v. at a dose of 60 or 300 U/kg/d for 10 d from day 9-11 to 18-20, attenuated these pathological changes in a dose-dependent manner. Histological examination of the kidney revealed that AT III prevented the occurrence of arteriosclerosis and thickening of the capillary basement membrane. However, the pathological changes induced by salt-loading were not attributable to activation of the blood coagulation system. These results demonstrate that AT III has preventive action against salt-induced hypertension and proteinuria in pregnancy through a mechanism largely independent of its anticoagulant action. AT III may thus be beneficial for the treatment of clinical symptoms of preeclampsia.

Animals↗
PubMed1994

Nitric oxide mediates the sustained opening of NMDA receptor-gated ionic channels which follows transient excitotoxic exposure in hippocampal slices.

In the rat hippocampal slice, a brief exposure to glutamate and glycine increased MK-801 binding to 246% of controls. Increased binding persisted 90 min after removal of those amino acids from the incubation medium. Posttreatment with the competitive substrate inhibitor of nitric oxide synthase, N omega-nitro-L-arginine or with hemoglobin, which binds NO extracellularly, inhibited this postexcitotoxic increase in MK-801 binding. L-Arginine reversed this inhibitory effect but D-arginine did not. The combination of tetrodotoxin and low Ca2+, which blocks transmitter release prevented the poststimulation increase in MK-801 binding, suggesting a presynaptic component. These findings suggest that the sustained opening of NMDA receptor-gated ionic channels seen after transient glutamate/glycine stimulation is mediated by NO.

Animals↗
PubMed1994

Nitric oxide participates in excitotoxic mechanisms induced by chemical hypoxia.

Changes in the activity of the NMDA receptor-gated ionic channels induced by potassium cyanide were studied in rat hippocampal slices utilizing a [3H]MK-801 binding technique. A 30-min exposure of slices to potassium cyanide (KCN) increased MK-801 binding by 252%. Co-application of N omega-nitro-L-arginine (NNLA), a competitive antagonist of nitric oxide (NO) synthase, reduced this increase by 72%. This inhibition by NNLA was completely reversed by an excess of L-arginine, a substrate for NO synthase, suggesting that the KCN-induced increase in MK-801 binding is mediated by NO synthase activity. KCN had no effect on MK-801 binding in synaptic membranes. In Ca(2+)-containing medium, KCN increased the release of glutamate, aspartate and glycine by 4- to 5-fold, and this was blocked by application of NNLA. NNLA inhibition was reversed by an excess of L-arginine, indicating that KCN-stimulated release of these amino acids is mediated by NO synthase activity. In Ca(2+)-free medium, a KCN-induced increase in MK-801 binding and in excitatory amino acid release was also observed, however, this increase was not influenced by NO-related agents, suggesting that these changes were not mediated by NO synthase activation. NNLA given after the end of exposure to KCN did not reverse the increase in MK-801 binding. These findings suggest that NO is involved in the initial activation of NMDA receptor-gated ionic channels and in the enhanced amino acid transmitter release induced by KCN, but that KCN can also induce some of these effects by a Ca(2+)- and NO-independent mechanism.

Amino Acids↗
PubMed1989

Antiulcerogenic compounds isolated from Chinese cinnamon.

Two active compounds that prevent serotonin-induced ulcerogenesis in rats were isolated from Chinese cinnamon (the stem bark of Cinnamomum cassia) and identified as 3-(2-hydroxyphenyl)-propanoic acid and its O-glucoside. The former compound, administered orally or parenterally to rats at a remarkably low dose (40 micrograms/kg body weight), also inhibited gastric ulcers induced by the other ulcerogens such as phenylbutazone, ethanol, and water immersion stress, although it failed to prevent indomethacin-induced ulcers. Pharmacological studies have shown that 3-(2-hydroxyphenyl)-propanoic acid hardly inhibited the secretion of gastric acid, but promoted the gastric blood flow. These results suggest that the antiulcerogenic effect of this compound is probably attributable to the potentiation of defensive factors through the improvement of the circulatory disorder and gastric cytoprotection.

Animals↗