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Biomedical subjects

Y Takiguchi

Publications and source records attributed to Y Takiguchi.

At least 73 records · Page 4Linked to original sources
PubMed1994

Enhancement of thrombolytic efficacy of tissue-type plasminogen activator by adjuvants in the guinea pig thrombosis model.

Reocclusion following thrombolysis is a major limitation of thrombolytic therapy with recombinant tissue-type plasminogen activator (rt-PA). We investigated the effects of vapiprost ((1R-(1 alpha(Z),2 beta,3 beta,5 alpha))-7-(5-((1,1'-biphenyl)-4-yl-methoxy)- 3-hydroxy-2-(1-piperidinyl)cyclopentyl)-4-heptenoic acid, a thromboxane A2 receptor antagonist); argatroban ((2R,4R)-4-methyl-1-[N2-(3-methyl-1,2,3,4-tetrahydro-8-quinolinyl)sulfon yl] - L-arginyl)]-2-piperidine-carboxylic acid, a specific thrombin inhibitor) and MK-886 (3-[1-(4-chlorobenzyl)-3-t-butyl-thio-5-isopropylindol-2-yl]-2,2- dimethylpropanoic acid, a specific leukotriene biosynthesis inhibitor) on the thrombolytic efficacy of rt-PA. The guinea pig femoral artery was thrombotically occluded by photochemical reaction between rose bengal and green light. Thirty min after the occlusion, rt-PA was administered and the time (T1) for reopening of the vessel and the frequency of reocclusion (Fro) 24 h after thrombolysis were monitored. With rt-PA alone, T1 was 28 +/- 7 min (n = 10) and Fro was 70%. T1 was reduced to 9 and 20 min by a combination of rt-PA with vapiprost and argatroban respectively. Fro was reduced by all three adjuvants. Histological observations revealed extensive adherence of polymorphonuclear leucocytes to the damaged endothelium at the site of thrombolysis. It is concluded that thromboxane A2, thrombin and leucocytes are involved in reocclusion after thrombolysis.

Adjuvants, Pharmaceutic↗
PubMed1994

Genomic structure of the mouse apurinic/apyrimidinic endonuclease gene.

A mammalian apurinic/apyrimidinic endonuclease (AP endonuclease) is known to have two distinct functional domains. One domain is responsible for regulating the activity of Fos/Jun proto-oncogene products to bind to DNA at specific recognition sites. The other domain, which is highly conserved from bacteria to mammals, is responsible for repairing DNA damage caused by ionizing radiation, oxidative damage, and alkylating agents. This study reports on the isolation and characterization of the genomic structure of the mouse AP endonuclease gene (Apex). The genomic sequence of the Apex gene was 2.14 kb in length and contained four exons. Exon 1 contained a 0.24-kb untranslated 5' region upstream of the initiation codon. Consensus sequences for two CAAT boxes and a GC box were found upstream of the end of exon 1. A polymorphism was noted in the untranslated region of exon 1 in a comparison of a number of mouse strains. These data indicate that the 5' end of the mouse gene (Apex) differs from the previously isolated human gene (Ape), which has five exons and an untranslated region between exons 1 and 2. Data are also presented that suggest the presence of two pseudogenes in the mouse.

Amino Acid Sequence↗
PubMed1994

[An autopsy case of lung cancer metastasizing to renal cell cancer and rectal villous adenoma].

A 67-year-old woman with bloody stool was admitted to our hospital. Chest radiograph on admission showed a tumor shadow in the right lower lung field. Lung adenocarcinoma of right S6 and villous adenoma of the rectum were detected. Although she was treated with chemotherapy and radiotherapy, she died of respiratory failure. At autopsy, moderately differentiated adenocarcinoma of the right lung, renal cell carcinoma, and villous adenoma of the rectum were confirmed. Lung adenocarcinomas were detected in the focus of the renal cell carcinoma and in the villous adenoma. Metastasis of a cancer into another coexisting tumor in the same individual is extremely rare, and a satisfactory explanation for this phenomenon has not yet been offered.

Adenocarcinoma↗
PubMed1994

[Computed tomographic appearances of pulmonary alveolar proteinosis].

We evaluated longitudinal changes in chest CT images in six cases (5 males and one female, age: 35-57 yr) of pulmonary alveolar proteinosis treated with bronchopulmonary lavage. Chest CT images on admission showed a mixed pattern of air-space consolidation and reticular or reticulonodular shadows in most cases and showed a peripheral clear zone in all cases. These shadows gradually diminished after bronchopulmonary lavage. Some cases revealed early improvement in the hilar zone while others had equal improvement in all lung lesions. In one case, consolidation was changed into reticular shadows by treatment. Previous reports have indicated that "interstitial shadows which disappeared with lavage" reflect edematous thickening of interlobular septa. However, our longitudinal evaluation suggests that interstitial shadows on CT images may reflect not only real interstitial infiltration but also inhomogeneous distribution of intralobular deposits.

Adult↗
PubMed1993

Roles of platelet-activating factor, thromboxane A2, ADP and thrombin in thrombogenesis in the guinea pig.

The mediators of photochemically induced thrombosis in the femoral artery of guinea pig were investigated. The femoral artery was occluded by a thrombus about 7 min after the initiation of photochemical reaction between rose bengal and green light. Pretreatment with a specific thromboxane (TX) A2 receptor antagonist, vapiprost, a platelet-activating factor (PAF) antagonist, WEB-2086, and ADP-induced platelet aggregation inhibitor, ticlopidine, prolonged the time to occlusion. Within the range of doses used, platelet aggregation in whole blood, which was induced by U-46619, PAF and ADP ex vivo, was inhibited by vapiprost, WEB-2086 and ticlopidine, respectively. In contrast, argatroban, a thrombin inhibitor, had no effect on the time to occlusion, although the dose of argatroban was sufficient to delay the prothrombin time and the activated partial thromboplastin time and to inhibit thrombin-induced platelet aggregation ex vivo. These results suggest that TXA2, PAF and ADP are involved in photochemically induced thrombosis of the guinea pig femoral artery, although the coagulation cascade does not play an important role.

Adenosine Diphosphate↗
PubMed1993

A simple and reproducible cerebral thrombosis model in rats induced by a photochemical reaction and the effect of a plasminogen-plasminogen activator chimera in this model.

In this study a new model of cerebral ischemia, based on a middle cerebral artery (MCA) thrombosis in rats is described. Furthermore, the effect of the novel plasminogen activator (SUN9216), a plasminogen-plasminogen activator chimera, comprising the fibrin kringle 1 domain of a plasminogen, and the two kringles, and the serine protease domains of wild-type tissue plasminogen activator (t-PA), including a modification of the mannose glycosylation site on the kringle 1 of t-PA (PK1de1FE1X), was studied in this model. In the newly described model of thrombotic cerebral ischemia, an occlusive thrombus occurred usually within 8 min in the MCA as a consequence of an endothelial injury subsequent to a photochemical reaction between a systemically administered photosensitive dye (rose bengal) and a transillumination of the MCA with a high-intensity green light with a wavelength of 540 nm. The study was quantitated by means of pathological examination of the MCA and the brain. A platelet-rich thrombus was observed in the MCA using electron microscopical analysis based on ion beam bombardment. At 24 hr after induction of the thrombus, the brain was removed from 13 control animals, nine coronal sections were stained from each brain with triphenyltetrazoliumchloride (TTC), and the ischemic area was quantitated. A constant area of infarction was observed in the cortex and the lateral part of the basal ganglia. In a second group (n = 8), at 1 or 8 weeks after induction of the thrombosis in the MCA, the coronal sections were stained with hematoxylin and eosin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

[New animal models for drug discovery research: focus on cardiovascular diseases].

Development of novel drugs relies on research to discover new drugs. Testing and evaluating new drugs on human subjects are usually impossible because of ethical concerns. Therefore, for drug discovery research, it is essential to establish animal models of human diseases. Numerous animal models have been developed and used in drug discovery and evaluation studies. Such animal models have had important roles in developing new drugs as well as understanding the etiologies of diseases. In the field of cardiovascular drugs, several interesting animal models are currently in use. These include, transgenic mice carrying both human renin and human angiotensinogen genes, Watanabe's heritable hyperlipidemic rabbits, rats with pulmonary hypertension induced by monocrotaline, myocardial infarction model, cardial hypertrophy model and photochemical thrombosis models. It is envisaged that for drug discovery and development, the search for more physiological animal models will continue in the future.

Animals↗
PubMed1993

Hemodynamic effects on thrombogenesis and platelet aggregation in spontaneously hypertensive rats.

The present study was conducted to investigate the effect of hypertension on the formation of arterial thrombus in the rat femoral artery. The time required to establish the thrombus following endothelial injury in spontaneously hypertensive rats (SHR) was extremely prolonged. Pretreatment with prazosin which lowered the blood pressure near the level in normotensive Wistar Kyoto (WKY) rats, significantly shortened the thrombogenesis time, but it was still longer than that in WKY rats. Platelet aggregation in response to collagen with washed platelets and whole blood was reduced in SHR with and without hypotensive treatment, in comparison with that in WKY rats. Prazosin did not affect the platelet aggregability. Therefore, the decreased platelet aggregation was considered to be responsible for the delayed thrombus formation in hypotensively treated SHR. These results suggested that high blood pressure, mainly, interferes with the establishment of thrombus directly. Hypoaggregability of platelets is likely to be partly involved in the prolongation of thrombogenesis in SHR.

Animals↗
PubMed1993

A thrombosis model for evaluating thrombolytic agents in the guinea-pig: comparison of t-PA, scu-PA and a novel thrombolytic agent, staphylokinase, on thrombolytic activity.

We have studied three fibrin-specific thrombolytic agents in a photochemically-induced, guinea-pig femoral artery model of thrombosis. Tissue-type plasminogen activator (t-PA, 0.3 and 1 mg/kg), single-chain urokinase-type plasminogen activator (scu-PA,5 and 15 mg/kg) and a novel thrombolytic agent, staphylokinase (SAK, 0.3 and 1 mg/kg) were intravenously infused for 30 min after arterial occlusion by a photochemically-induced reaction between rose bengal and light (540 nm). These thrombolytic agents induced thrombolysis in 17-66% of animals and 24 h later, reocclusion occurred in 75-100%. t-PA hardly altered plasma fibrinogen throughout the experimental period. In contrast, scu-PA (15 mg/kg) decreased plasma fibrinogen and alpha 2-antiplasmin levels by 25% and 90% respectively 90 min after beginning the infusion. SAK markedly decreased plasma fibrinogen and alpha 2-antiplasmin levels in dose- and time-dependent manners. These results suggest that this model of thrombosis has a relatively high sensitivity to t-PA, which induced thrombolysis without decreasing fibrinogen and alpha 2-antiplasmin, compared with the other two fibrin-specific thrombolytic agents.

Animals↗
PubMed1993

[A case of polypoid bronchial neurofibroma originating from right B2b successfully treated by bronchoscopic snaring forceps and Nd-YAG laser therapy].

A 34-year-old man with persistent cough was admitted to our hospital. Bronchoscopic examination revealed a polypoid tumor with smooth surface which almost completely obstructed the right main bronchus. The tumor was removed by transbronchial snaring forceps and histologically confirmed as neurofibroma. Residual tumor was excised by biopsy forceps and further endoscopic Nd-YAG laser vaporization was performed. This is the first case in our country in which bronchoscopic treatment was performed for bronchial neurofibroma. Bronchoscopic removal might be the preferred treatment in the present case, although long-term follow-up is also required.

Adult↗
PubMed1992

Comparison of the inhibitory effects of the TXA2 receptor antagonist, vapiprost, and other antiplatelet drugs on arterial thrombosis in rats: possible role of TXA2.

The antithrombotic effect of the thromboxane A2 receptor antagonist, vapiprost, was compared with those of other antiplatelet drugs using an arterial thrombosis model which utilized photochemical reaction in the rat femoral artery. Vapiprost prolonged the time required to occlude the artery with thrombus and inhibited collagen-induced rat platelet aggregation in whole blood ex vivo, in a dose-dependent manner. The potency ranking of antithrombotic effect was vapiprost > ketanserin (serotonin 5-HT2 receptor antagonist) >> ticlopidine (inhibitor of ADP-induced platelet aggregation) = dipyridamole (adenosine uptake inhibitor) > aspirin (cyclooxygenase inhibitor). On the other hand, the ranking of antiplatelet effect was ticlopidine > or = vapiprost > or = aspirin. Ketanserin and dipyridamole were ineffective. Relative to their antiplatelet effect, vapiprost and ketanserin had powerful antithrombotic effects. It is possible that the potent antithrombotic effects of vapiprost and ketanserin in vivo reflect the ability of these drugs to inhibit mediator-induced vascular contractions in addition to platelet aggregation. The results of the present study also suggest that TXA2 may play an important role in thrombogenesis in rats.

Animals↗
PubMed1992

Arterial thrombosis model with photochemical reaction in guinea-pig and its property.

We have already developed an arterial thrombosis model in the rat femoral artery which utilized photochemical reaction between systemically injected rose bengal and transillumination of a green light with 540 nm wave length from the outside of the vessel. In the present study, we applied this model to guinea-pigs in order to produce a more suitable thrombus model for evaluation of antithrombotic drugs which act on the prostaglandin cascade. In the guinea-pigs, the irradiated femoral artery was completely occluded in 7 min after the injection of rose bengal (10 mg/kg) in a similar manner to the rats. The processes of primary endothelial injury and the subsequent formation of thrombus during this manipulation were observed by the electron microscopy. Pretreatment with aspirin and Y-20811, a thromboxane synthetase inhibitor, significantly prolonged the time required for occlusion in the guinea-pigs, while these drugs were ineffective in the rats. The antithrombotic effect of vapiprost, a thromboxane A2 receptor antagonist, was more pronounced in the guinea-pigs than the rats. In conclusion, this model in guinea-pigs is more suitable for evaluating antithrombotic drugs, particularly, the action of which is exerted involving the prostaglandin cascade.

Animals↗
PubMed1992

Effect of aldose reductase inhibitor on the inhibition of platelet aggregation induced by diabetic rat plasma.

Plasma isolated from streptozotocin-induced diabetic rats inhibited platelet aggregation. Treatment of diabetic rats with an aldose reductase inhibitor, ONO-2235, which did not improve hyperglycemia, prevented the antiaggregating activity of plasma as did insulin treatment. Both treatments reduced the elevated sorbitol concentrations in erythrocytes. Although the factor(s) accounting for the antiaggregatory effect of diabetic plasma has not yet been characterized, it is possible that the accumulation of sorbitol in erythrocytes is related to the generation of the factor(s).

Aldehyde Reductase↗
PubMed1992

NIH3T3 transfectant containing human K-ras oncogene shows enhanced metastatic activity after in vivo tumor growth or co-culture with fibroblasts.

A clone of NIH3T3 transformant (H-3), obtained by transfecting genomic DNA of a human colon carcinoma cell line, contains human K-ras oncogene and yields metastatic pulmonary nodules after intravenous injection of the cells into nude mice. This metastatic ability was enhanced remarkably after in vivo tumor growth (subcutaneous tumor formation in nude mice) accompanied by increased mRNA expression and gene amplification of the human-derived K-ras oncogene, while it declined gradually as the passage number increased in vitro, with corresponding decreases of gene amplification and mRNA expression. Six subclones were randomly selected from H-3 cells which had been subcultured to passage 22. All of the clones in culture showed almost the same low level of metastatic ability and exhibited little K-ras oncogene amplification with correspondingly low mRNA expression. However, after they formed tumors in nude mice, every clone acquired high metastatic ability and the gene amplification increased, with elevated mRNA expression. These experimental facts indicated that acquisition of metastatic ability coupled with the function of K-ras oncogene was conditional in nature, being strongly affected by in vivo tumor circumstances. The low metastatic and G-418-resistant H-3 cells were co-cultured with BALB/c3T3 fibroblasts for 2-4 weeks. After removal of fibroblasts by exposure to G-418, the tumor cells exhibited increased metastatic ability and human K-ras oncogene mRNA, suggesting an intimate interaction between H-3 cells and fibroblasts influencing the function of transfected human K-ras oncogene. Fibroblasts of the host animal may thus have an important role in generating enhanced metastatic activity of H-3 cells.

3T3 Cells↗
PubMed1992

Interleukin-11: a novel stroma-derived cytokine.

Interleukin-11 (IL-11) is a novel stroma-derived cytokine that acts on both hematopoietic progenitors and stromal cells. IL-11 was originally identified in a medium conditioned by the macaque bone marrow-derived stromal cell line PU-34 and cloned as a growth factor for the IL-6-dependent plasmacytoma cell line T1165. IL-11 stimulates T-cell dependent development of antibody-producing B cells and is synergistic with IL-3 to stimulate megakaryocyte colony formation. Adipogenesis inhibitory factor (AGIF) was cloned from the human bone marrow-derived stromal cell line KM-102. The AGIF cDNA sequence was revealed to be identical to that of the IL-11 cDNA. AGIF inhibits the process of adipogenesis of the bone marrow-derived preadipocyte cell line H-1/A. Other biological activities such as stimulation of stem-cell proliferation, erythropoiesis, lymphohematopoiesis and hepatic acute-phase response are also summarized. The human IL-11 gene consists of five exons and four introns, and was mapped on chromosome 19 at band 19q13.3-q13.4. A single class of high-affinity IL-11 receptor (IL-11R) of 151 kDa is present on 3T3-L1 preadipocytes. A protein-tyrosine kinase pathway may be involved in the initiation of the IL-11R-mediated signal transduction.

Animals↗
PubMed1992

Effects of vapiprost, a novel thromboxane receptor antagonist, on thrombus formation and vascular patency after thrombolysis by tissue-type plasminogen activator.

1. A thrombus was induced in the rat femoral artery by endothelial damage due to the photochemical reaction between systemically-injected Rose Bengal and transillumination with green light (wavelength: 540 nm). The artery of the control rat was completely occluded in 302.8 +/- 27.0 s after the initiation of the reaction. 2. Pretreatment with vapiprost (0.1, 0.3 and 1.0 mg kg-1, i.v., 5 min before the reaction) prolonged the time required to occlude the femoral artery in a dose-dependent manner. The efficacy of vapiprost on the time required for occlusion was over 10 times higher than that of aspirin which was administered 30 min before the reaction. 3. The thrombolytic effects of tissue-type plasminogen activator (tPA) on the established arterial thrombus in the presence and absence of vapiprost were also studied in the same model. When vapiprost (0.3 mg kg-1, i.v.) was administered just before tPA infusion (100 micrograms kg-1 min-1 for 30 min), the time required to reperfuse the occluded artery was reduced, the incidence of the reperfusion was increased and the arterial blood flow after reperfusion was improved. 4. When vapiprost (1.0 mg kg-1 daily p.o.) was administered for 1 week after the establishment of reperfusion by tPA combined with vapiprost, the patency of the reperfused artery was improved and the femoral arterial blood flow was better preserved than after treatment with only tPA. 5. These findings suggest that this thromboxane receptor antagonist may be a useful adjunct to anti-thrombotic therapy. The combination therapy with tPA may be more effective than treatment with tPA alone and provides greater protection against reocclusion after reperfusion.

Animals↗
PubMed1992

Role of cell-mediated immune reaction in blister formation of bullous pemphigoid.

In patients with bullous pemphigoid (BP), early lesions appear as exudative erythematous patches. Histologically, the inflammatory infiltrate is composed mainly of mononuclear cells (MNCs) in the erythematous lesion, although eosinophils and neutrophils are also present. The MNCs are predominantly helper/inducer T cells even in the bullous lesions. Some of the MNCs infiltrated were stained in cytoplasm by antihuman gamma-interferon (IFN-gamma) monoclonal antibody (MoAb) immunohistologically. These infiltrates are considered to produce IFN-gamma. In the bullous fluids of early BP lesions, high levels of IFN-gamma are detected by radioimmunoassay using antihuman IFN-gamma MoAb. The results suggest that infiltrating lymphocytes are stimulated immunologically in BP bullous lesions. Cell-mediated immune reaction as well as autoantibody to the basement membrane zone may also play an important role in blister formation in BP.

B-Lymphocytes↗