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Biomedical subjects

H Koike

Publications and source records attributed to H Koike.

At least 145 records · Page 8Linked to original sources
PubMed1995

Pharmacology of CS-866, a novel nonpeptide angiotensin II receptor antagonist.

CS-866, (5-methyl-2-oxo-1,3-dioxolen-4-yl)methoxy-4-(1-hydroxy-1- methylethyl)-2-propyl-1-(4-[2-(tetrazol-5-yl)-phenyl]phenyl)met hylimidazol- 5-carboxylate, a prodrug type angiotensin receptor antagonist, is deesterified to the active acid, RNH-6270. RNH-6270 inhibited [125I]angiotensin II binding to bovine adrenal cortical membranes (angiotensin AT1 receptors) with an IC50 value of 7.7 nM, but not [125I]angiotensin II binding to bovine cerebellar membranes (angiotensin AT2 receptors), indicating the selectivity of the compound for angiotensin AT1 receptors. In guinea pig aortas, RNH-6270 reduced the maximal response of the concentration-contractile curve for angiotensin II (pD'2 = 9.9), but had no effect on the contractile response induced by phenylephrine or KCl. In conscious rats, intravenously injected RNH-6270 inhibited angiotensin II-induced pressor responses in a dose-dependent manner, and orally administered CS-866 produced a long-lasting inhibition of angiotensin II pressor responses. SK&F-525A, a P-450 inhibitor, suppressed the angiotensin II inhibitory effect of losartan, but not that of CS-866. These results demonstrate that RNH-6270 is a potent and AT1-selective angiotensin receptor antagonist and that, after oral administration, CS-866 has a long-lasting angiotensin II inhibitory action which is not affected by drug metabolizing enzymes in the liver.

Adrenal Cortex↗
PubMed1995

Localization of rat endothelin-converting enzyme to vascular endothelial cells and some secretory cells.

Endothelin is a potent vasoconstrictive peptide that is produced by vascular endothelial cells; it is formed from its precursor, big endothelin, by endothelin-converting enzyme (ECE). In this work, ECE was studied using specific monoclonal antibodies. In immunoblotting, ECE was estimated to be a 300 kDa protein on SDS/PAGE under non-reducing conditions, and 130 kDa under reducing conditions. Cross-linking experiments revealed that ECE is composed of two disulphide-linked subunits. Localization of ECE was studied at the cellular and subcellular levels in various rat tissues and cells. High-level expression of ECE was observed in membrane fractions of simian virus 40-transformed rat endothelial cells by immunoblotting, but the immunoreactive band was absent form aortic smooth muscle cells and cytosolic fractions of endothelial cells. In immunohistochemical analysis, ECE was found to be localized in the endothelial cells of the aorta, lung, kidney, liver and heart. Confocal immunofluorescent microscopy showed that most of the ECE in endothelial cells and cells transfected with ECE cDNA was clustered along the plasma membrane. Intact COS or CHO cells transfected with ECE cDNA rapidly and efficiently cleaved big endothelin-1 added to the culture medium. Thus endothelial cells express ECE on the plasma membrane and the active site of the enzyme faces outside the cells, i.e. it is an ectoenzyme. Other than endothelial cells, ECE was also present in some secretory cells. The enzyme was abundant in the adrenal gland, and localized in chromaffin cells. ECE was also highly condensed in pancreatic islet beta cells. It is concluded that ECE and endothelin may be involved in the regulated secretion of hormones.

Adrenal Glands↗
PubMed1995

Clinical implications of metastases to the ovary.

Predictive factors for ovarian metastases were analyzed in 313 autopsy cases of women dying of malignancy. Genital, hematopoietic, brain tumors, and double primaries were excluded. Ovarian metastases were found in 60 of 313 (19.2%) cases. The primary sites of origin were stomach (18 cases), breast (13), pancreas (7), bile duct (7), large intestine (4), kidney (3), liver (2), lung (1), and other (5). The percentages of ovarian metastasis in each primary site were 50% (3/6) in the kidney, 38.3% (18/47) in the stomach, 30.8% (4/13) in the large intestine, 22.9% (13/57) in the breast, 22.6% (7/31) in the bile duct, 19.4% (7/36) in the pancreas, 5.4% (2/37) in the liver, and 3.4% (1/29) in the lung. Seventy-five percent (75%) of ovaries with metastasis were 5 cm or less in the greatest dimension. Seventy-eight percent (78%) of ovarian metastases were bilateral. Fifty-one percent (51%) of the involved ovaries were cystic. Twenty-four percent (24%) of the metastasis were occult in which microscopic disease was present in normal appearing ovaries. The mean age of death in the cases with ovarian metastasis was 53.8 +/- 16.8 years. This was significantly younger than the mean age without ovarian metastasis that mainly was attributable to the younger ages for breast and bile duct cancer. The number of other extraovarian metastatic sites for positive ovarian cases was significantly greater than for the negative ovarian cases (7.6 +/- 2.4 and 5.8 +/- 2.5, respectively). This difference was dominant in gastric and bile duct cancers. The other metastatic sites that accompanied ovarian metastases were the adrenal gland in gastric cancer, the spleen and small intestine in breast cancer, and the adrenal gland and colon in bile duct cancer. The frequency of peritoneal dissemination was essentially the same between cases with positive and negative ovarian metastasis. Scirrhous adenocarcinoma of the stomach more commonly metastasized to the ovary than any other stomach histological type. These findings suggest that although the impact upon outcome of bilateral salpingo-ophorectomy at the initial operation is unknown, the discovery of ovarian metastases in a large proportion of patients may dramatically alter initial management in patients otherwise thought to have only local disease.

Adolescent↗
PubMed1995

Tissue-selective inhibition of sterol synthesis in mice by pravastatin sodium after a single or repeated oral administrations.

Pravastatin, an inhibitor of 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase, exhibits liver-selectivity in inhibiting sterol synthesis, when administered as a single oral dose to mice or rats, whereas lovastatin and simvastatin do not. This may be due to the fact that pravastatin is distributed intracellularly, to a large extent, in the liver and extracellularly in nonhepatic tissues. In the present study, we examined whether the difference in liver-selectivity among these three HMG-CoA reductase inhibitors observed in single-dose studies was preserved after repeated oral administrations of drugs to mice. De novo sterol synthesis in different tissues of mice was examined in vivo three hours after the last dose of drug by measuring incorporation of intraperitoneally injected [14C]acetate into total sterols. Pravastatin administered orally for 11 consecutive days at 5 and 10 mg/kg exhibited a greater liver-selectivity than lovastatin and simvastatin: sterol synthesis was inhibited more than 60% in the liver by all three drugs, whereas that in nonhepatic tissues was inhibited less than 10% by pravastatin and more than 30% by lovastatin and simvastatinin in most of the nonhepatic tissues examined. Pravastatin administered orally for 11 consecutive days at 10 mg/kg caused more selective inhibition of sterol synthesis in liver ex vivo than two other inhibitors at the same dose. Pravastatin inhibited de novo sterol synthesis from [14C]acetate into sterol fraction in the liver slices in vitro, but minimally in those of the spleen and testis, whereas lovastatin and simvastatin inhibited in those of all three tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Development of the otolith organs and semicircular canals in the Japanese red-bellied newt, Cynops pyrrhogaster.

The sequence in which the otoliths and semicircular canals and their associated sensory epithelia appear and develop in the newt are described. Three-dimensional reconstruction of serial sections through the otic vesicle of newt embryos from stages 31 through 58 demonstrate the first appearance, relative position and growth of the otoliths. A single otolith is first seen in stage 33 embryos (approximately 9 days old); this splits into separate utricular and saccular otoliths at stage 40 (13 days). The lateral semicircular canal is the first to appear, at stage 41 (14 days). The anterior and posterior canals appear approximately one week later and the vestibular apparatus is essentially fully formed at stage 58 (approximately 5 weeks). The data reported here will serve as ground-based controls for fertilized newt eggs flown on the International Microgravity Laboratory-2 Space Shuttle flight, to investigate the influence of microgravity on the development of the gravity-sensing organs.

Animals↗
PubMed1995

Non-invasive assessment of otolith formation during development of the Japanese red-bellied newt, Cynops pyrrhogaster.

Pre-mated adult female newts and embryos have been flown on the International Microgravity Laboratory-2 (IML-2) Space Shuttle flight in 1994 (Wiederhold et al., 1992b). With the specimens available from this flight, the calcification of otoliths, ulna, radius and backbone of the flown larvae and adult newts were analyzed. The experiments presented here studied the development of the otoliths on the ground. Otoliths of living newts, from embryo to adult, were observed in situ with the application of a new X-ray and bio-imaging analyzer system. For the establishment of this method, newts at different developmental stages were used. An imaging plate temporarily stores the X-ray energy pattern at the bio-imaging analyzer. A latent image on the imaging plate was transformed into a digital time series signal with an image reader. Acquired digital information was computed with the image processor. The processed information was recorded on film with an image recorder, in order to visualize it on an enlargement computed radiograph. To analyze development of the otoliths, photo-stimulated luminescence level was detected by an image analyzer, using transmitted X-ray photons. A single clump of otoconia could first be seen at stage 33. Stage-36 embryos first have distinguishable otoliths, with the utricle in front and saccule behind. Our results show that this X-ray method detects the otoliths equally as well as sectioning. In the newt, the mandibular/maxillary bone formed before the spine. It is suspected that for the newt embryo, living in water, feeding becomes necessary prior to support of the body.

Animals↗
PubMed1995

Inhibition of restenosis by beraprost sodium (a prostaglandin I2 analogue) in the atherosclerotic rabbit artery after angioplasty.

We examined the effect of beraprost sodium (BPS), a stable prostaglandin I2 (PGI2) analogue, on restenosis after balloon angioplasty in the atherosclerotic artery in rabbits. Regional atherosclerosis was induced in the femoral artery of New Zealand white rabbits by balloon deendothelialization and 2% cholesterol diet. After establishment of atheroma in the femoral artery, angioplasty was performed. In all, 65 rabbits were assigned to the following six subcutaneous drug treatment groups: control group (n = 13, saline 0.25 ml/kg); BPS low-dose group (n = 11, BPS 50 micrograms/kg twice daily); BPS high-dose group (n = 12, BPS 100 micrograms/kg twice daily); 2-day BPS high-dose group (n = 11, BPS 100 micrograms/kg twice daily for 2 days after angioplasty); aspirin (ASA) group (n = 10, ASA 30 mg once daily); and BPS+ASA group (n = 8, BPS 50 micrograms/kg twice daily plus ASA 30 mg once daily). Administration of each drug was started 30 min before balloon angioplasty and was continued until 4 weeks thereafter, except in the 2-day BPS high-dose group. Re-examination 4 weeks after the angioplasty showed significant (p < 0.05) preservation of the luminal diameter in the BPS high-dose and 2-day BPS high-dose groups (1.30 +/- 0.15 and 1.25 +/- 0.09 mm, respectively) as compared with that in the control group (0.83 +/- 0.10 mm); however, the luminal diameter in the BPS low-dose, ASA, and BPS+ASA groups (0.94 +/- 0.18, 1.06 +/- 0.11, and 1.05 +/- 0.15 mm, respectively) was not significantly different from that in the control group.

Administration, Oral↗
PubMed1995

Beneficial effects of beraprost sodium, a stable prostacyclin analogue, in diabetic cardiomyopathy.

We examined whether beraprost sodium (beraprost), a stable prostacyclin analogue, prevented cardiomyopathy in diabetic rats in vivo. Diabetes was induced by a bolus injection of streptozotocin in rat-tail vein. Four weeks after the induction of diabetes, the animals were treated with beraprost (30 micrograms/kg/day, p.o.) for 4 weeks until they were used for the measurement of hemodynamics, electrocardiogram (ECG), and plasma creatine phosphokinase (CK) activity. Nontreated diabetic rats have lower mean blood pressure, heart rate, left ventricular systolic pressure, and peak positive dP/dt at basal levels compared to age-matched normal rats. All of these changes were not improved in beraprost-treated rats. The left ventricular end-diastolic pressure and ST/R ratio in the ECG were significantly increased in diabetic rats. These parameters were significantly improved by beraprost compared with nontreated diabetic rats. Additionally, beraprost significantly suppressed the elevation of plasma CK activity as compared with that in non-treated diabetic rats. Changes in peak positive dP/dt in response to isoproterenol were attenuated in nontreated diabetic rats as compared with age-matched normal rats and beraprost-treated diabetic rats. These results suggest that beraprost is capable of preventing diabetic cardiomyopathy without affecting hyperglycemic condition.

Administration, Oral↗
PubMed1995

Existence and differential changes of peptidylarginine deiminase type II in mouse yolk-sac erythroid cells.

Peptidylarginine deiminase (PAD) catalyzes the conversion of arginyl residues in proteins to citrullyl residues in the presence of Ca2+. Recently, we obtained a monoclonal antibody, EH7, which reacted only with mouse PAD type II. Here, we describe immunohistochemical findings on the cellular localization of PAD type II in mouse fetus by using the monoclonal antibody. PAD type II is expressed in yolk-sac erythroid cells and the level of the enzyme in these cells decreases as the cells differentiate.

Animals↗
PubMed1995

Cytopathologic observations of the lung of adult newts (Cynops pyrrhogaster) on-board the space shuttle, Columbia, during the Second International Microgravity Laboratory experiments.

Four adult female Japanese newts, Cynops pyrrhogaster, were carried for 15 days aboard the orbiting space shuttle, Columbia, in July of 1994, as part of the Second International Microgravity Laboratory, IML-2 aquatic animal experiments. These previously fertilized newts, after stimulation with chorionic gonadotropin by a spaceflight adapted injection procedure, deposited numerous eggs for study of early development during weightlessness. The primitive saccular lungs of the two newts which survived the spaceflight revealed by TEM marked pulmonary cytopathologic changes including basal laminar separation, microvillar degeneration, and cytoplasmic granular changes in the primary granulated pneumocytes. Also, intracellular edema in the pulmonary collagenous matrix and vacuolar changes in the ciliated pulmonary lining cell type and in vascular endothelial cells were observed. These changes, triggered by the spaceflight, and not seen in controls also relying on respiration via the skin, may reflect a chronic mild hypoxia as it is known that newts undergoing oviposition are subject to increased oxygen demand.

Animals↗
PubMed1995

[Myotonin protein kinase].

The mutation underlying myotonic dystrophy is the expansion of polymorphic CTG repeat in the 3'-noncoding region of the myotonin protein kinase (MtPK) gene mapping to chromosome 19q13.3. A full-length cDNA of human MtPK was cloned and expressed in COS-1 cells. MtPK is recovered from the COS cell extract as a 70 kDa protein, which coincides with the size deduced from the predicted amino acid sequence. Biochemical characteristics of MtPK expressed in COS cells and its expression are investigated.

Chromosomes, Human, Pair 19↗
PubMed1995

[A case report of active prosthetic valve endocarditis caused by MRSA].

A 53-year-old woman, who had undergone MVR and TAP 2 months ago at other hospital, was referred because of PVE caused by MRSA, mediastinitis and remaining AR. Emergency operation was performed, and it was found that mitral mechanical valve was detached and massive vegetation was present around prosthetic valve suture ring. MRSA was cultured from mechanical valve. Thorough debridement for mediastinitis and mitral annulus were performed. Diagnosis and timing of surgical intervention for mechanical PVE were discussed.

Endocarditis↗
PubMed1994

Effects of platelet activating factor receptor antagonists on intracellular platelet activating factor function in neutrophils.

We investigated the effects of the platelet activating factor (PAF) receptor antagonists, SM-12502 ((+)-cis-3,5-dimethyl-2-(pyridyl)- thiazolidin-4-one hydrochloride), WEB-2086 (3-(4-(2-chlorphenyl)-9-methyl-6H-thieno(3,2-f)-(1,2,4)triazolo(4, 3- a)(1,4)diazepin-2-yl)-1-(4-morpholinyl)-1-propanone) and RP-48740 (3-(3-pyridyl)-1H,3H-pyrrolo[1,2-c]thiazole-7-carboxamide) on the PAF-mediated activation of rat neutrophils. These antagonists inhibited PAF-induced degranulation and chemotaxis in neutrophils at a dose that correlated well with PAF-induced platelet aggregation based on the statistical analyses. N-formyl-L-methionyl-L-leucyl-L- phenylalanin (fMLP)-induced cellular responses were also inhibited by the PAF receptor antagonists, but their inhibitory potencies did not correlate with those for PAF-induced platelet aggregation. In addition, the doses required for inhibition were higher than those required against PAF-induced responses (i.e. IC50 ratio of WEB-2086, SM-12502 and RP-48740 in fMLP-induced/PAF-induced degranulation was 40.0, 2.8 and 5.6, respectively). PAF receptor antagonists inhibited inositol 1,4,5-triphosphate production and the release of Ca2+ from the intracellular store site after stimulation with PAF. In the fMLP-induced responses, PAF receptor antagonists did not inhibit IP3 production and Ca2+ release, but did inhibit transmembrane Ca2+ influx. These results suggest the presence of distinct PAF receptor subtype, to which exogenously added PAF binds, while endogenously produced PAF binds to the other. Intracellular PAF, which was produced by fMLP-stimulation, may play an important role in the late phase of signal transduction, and may participate in the transmembrane Ca2+ influx.

Animals↗
PubMed1994

Requirement of a COOH-terminal pro-sequence for the extracellular secretion of aqualysin I (a thermophilic subtilisin-type protease) in Thermus thermophilus.

Thermus thermophilus cells harboring an expression plasmid for the aqualysin I gene secrete the mature enzyme into the medium. In an Escherichia coli expression system, a precursor of the enzyme with the C-terminal pro-sequence is accumulated in the cells, and upon treatment at 65 degrees C the active enzyme is produced. One- to 10-amino acid residue deletions, as well as complete 105-residue deletion of the C-terminal pro-sequence from the C-terminus, did not affect the production of the enzyme in E. coli cells. T. thermophilus cells harboring plasmids for mutant precursors with one- and three-residue deletions secreted the enzyme extracellularly. However, transformants harboring plasmids for mutant precursors with deletions of five or more amino acid residues could not be obtained. These results suggest that the C-terminal pro-sequence plays an important role in the extracellular secretion of the enzyme in T. thermophilus cells.

Amino Acid Sequence↗
PubMed1994

[Studies on prostaglandin production relating to the mechanism of dysmenorrhea in endometriosis].

The relationship between prostaglandins (PGs) production and the mechanism of dysmenorrhea in endometriosis is poorly understood. Consequently, we investigated the role of PGs in dysmenorrhea of endometriosis. Slices of normal endometrium, normal myometrium, adenomyosis, leiomyoma, normal ovary and affected ovary were incubated. 6-keto PGF1 alpha (a metabolite of PGI2), TXB2 (a metabolite of TXA2), PGF2 alpha and PGE2 concentrations of the incubation medium were measured by RIA. The results are as follows; 1) PGs production in endometriosis was significantly higher than that of other tissues, especially 6-keto PGF1 alpha, which was a dominant product in adenomyosis. 2) There were significant differences in PGs production between severe dysmenorrhea and non dysmenorrhea, especially tissue of adenomyosis with severe dysmenorrhea which produces large amounts of 6-keto PGF1 alpha. 3) There seems to be interaction between normal endometrium and normal myometrium with regard to 6-keto PGF1 alpha production. We concluded that increased PGI2 in the tissue of endometriosis seems to induce hyperalgesia during menstruation.

6-Ketoprostaglandin F1 alpha↗