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Y Koibuchi

Publications and source records attributed to Y Koibuchi.

At least 55 records · Page 3Linked to original sources
PubMed1993

[Surgical treatment of pulmonary arteriovenous fistula: report of two cases].

Two patients with surgical intervention for pulmonary arteriovenous fistula were presented. Lobectomy was performed in a cyanotic patient and fistula excision in another. To prevent the unsatisfactory prognosis of pulmonary arteriovenous fistula, surgical treatment is preferable to drug therapy when the diagnosis of this disease is established. The operative method should be selected according to the size, shape and localization of pulmonary arteriovenous fistula.

Arteriovenous Fistula↗
PubMed1992

Study on stereospecificity of enzyme reaction related to peroxisomal bile acid synthesis in rat liver.

We examined stereoselectivities of enzymes related to bile acid formation in hepatic peroxisomes using two stereoisomers of 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestanoic acid (THCA) and its coenzyme A (CoA) derivatives. The activity of acyl-CoA synthetase for 25 S-THCA was 1.4-times higher than that for 25 R-THCA. The difference was also observed after clofibrate-treatment. This activity was located in microsomes, differing from palmitoyl-CoA synthetase located in mitochondria, peroxisomes and microsomes. There was no stereoselectivity in the reaction of peroxisomal fatty acyl-CoA oxidase for THCA isomers, and the activity was one tenth of that for acyl-CoA synthetase. Considering the overall reaction of peroxisomal bile acid formation, the stereoselective difference observed in THCA-CoA synthesis should be denied. Thus, the previous finding that the overall formation of bile acid from THCA was not stereoselective was further confirmed. Furthermore, the activity for THCA oxidation was not induced by clofibric acid, suggesting that there would be different isozymes of peroxisomal acyl-CoA oxidase against THCA-CoA and palmitoyl-CoA.

Acyl-CoA Oxidase↗
PubMed1991

Characteristics of the vasorelaxing action of (3E)-4-ethyl-2-hydroximino-5-nitro-3-hexamide FK409, a new vasodilator isolated from microbial sources, in isolated rabbit arteries.

We examined the vasoinhibitory effect of (3E)-4-ethyl-2-hydroximino-5-nitro-3-hexamide FK409, a new vasodilator, on contractile responses in isolated rabbit arteries. FK409 (10(-8)-10(-5) M) inhibited contractile responses to norepinephrine (NE), histamine (His), and 5-hydroxytryptamine (5-HT) in rabbit aorta. The pattern of inhibition by FK409 was not competitive. The inhibitory effect of FK409 on the 5-HT response was much greater than that of nitroglycerin (NG). A high concentration of FK409 (10(-5) M) was necessary to inhibit the response to KCl (10-70 mM). The effect of combined treatment with FK409 (10(-5) M) and a subthreshold concentration of nifedipine (10(-9) M) on the KCl response was much greater than a single treatment with either agent. In addition, 3 x 10(-6) M D600, but not FK409 (10(-6) or 10(-5) M), inhibited the increase in the rate of 45Ca influx stimulated by a 40-mM KCl substituted solution. In a Ca2(+)-free medium containing EGTA and nifedipine, FK409 (10(-9)-10(-5) M) inhibited phasic responses to NE, His, and 5-HT, and subsequent sustained responses owing to addition of Ca2+. The response to caffeine in rabbit iliac arteries incubated in Ca2(+)-free medium was also inhibited by FK409 (10(-6) and 10(-5) M). In rabbit aorta precontracted with NE (10(-5) M) and partially inhibited by prior exposure to NG (10(-5) M), the relaxing effect of FK409 was slightly attenuated. Pretreatment of tissues with FK409 (10(-6) M) inhibited the relaxing action of NG much more than prior NG inhibited the relaxing action of FK409. Methylene blue (10(-5) M), but not hemoglobin (10(-6) M), inhibited the relaxing action of FK409, whereas M&B 22,948 (3 x 10(-4) M) potentiated it. FK409 caused a relaxation of precontracted aorta without endothelium that was inhibited by methylene blue. In rabbit aorta precontracted with NE, FK409 (10(-6) M) increased cyclic GMP but not cyclic AMP content. FK409 (10(-5) M) had no effect on the NE-mediated increase in tissue inositol monophosphate (IP). These results suggest that FK409 inhibits the responses attributed to both intracellular Ca2+ release and Ca2+ influx through receptor-operated channels. The inhibitory effect of FK409 on both the KCl contractile response and KCl-stimulated 45Ca influx appears to be different from that of nifedipine or D600. Furthermore, the inhibitory action of FK409 may be partially mediated by cyclic GMP.

Animals↗
PubMed1989

Suppression of atherogenesis in cholesterol-fed rabbits treated with nilvadipine, a new vasoselective calcium entry blocker.

We examined the effects of nilvadipine, a new dihydropyridine calcium entry blocker, on atherogenesis in rabbits fed a 1% cholesterol diet. The drug was given subcutaneously to the animals in hypotensive doses of 1.0 or 3.2 mg/kg/day for 10 weeks, and was well tolerated. Plasma total cholesterol increased markedly in all the cholesterol-fed rabbits, and nilvadipine had no effect on this, or on HDL-cholesterol and triglyceride levels. However, the area of Sudan IV positive intimal lesions (one of the parameters of atherosclerosis) in the aorta decreased significantly in the nilvadipine treated animals, and in addition, cholesterol and calcium content in the thoracic aorta were reduced. The reference drugs, nifedipine and nicardipine given subcutaneously in doses of 10.0 mg/kg/day either had no effect or were weaker in antiatherogenic effect than nilvadipine. The findings suggest that nilvadipine has more potent antiatherogenic activity than nicardipine or nifedipine.

Animals↗
PubMed1989

Binding of the new calcium entry blocker nilvadipine to rat aortic and guinea pig left ventricular membranes.

The binding of 3H-nilvadipine to the vascular (rat aortic) and cardiac (guinea pig left ventricular) microsomes was reversible and saturable. The results of the competitive binding experiments showed that nilvadipine had a higher affinity (Kd: 1.5 +/- 0.2 nmol/l) for the vascular binding sites than did nifedipine (Kd: 10.7 +/- 0.8 nmol/l) and nicardipine (Kd: 6.9 +/- 2.0 nmol/l), while the affinity of nilvadipine for the cardiac binding sites (Kd: 3.8 +/- 0.4 nmol/l) was similar to that of nifedipine (Kd: 3.3 +/- 0.1 nmol/l) and nicardipine (Kd: 4.2 +/- 0.3 nmol/l). The time courses of dissociation of the unlabeled dihydropyridines from the vascular binding sites were investigated using 3H-nitrendipine. Nilvadipine and nicardipine dissociated more slowly from the binding sites than did nifedipine. These results suggest that the high potency, selectivity for the vascular smooth muscle and long duration of action of nilvadipine may be related to its binding properties.

Animals↗
PubMed1988

Effects of nilvadipine on the cardiovascular system in experimental animals.

The effects of 5-isopropyl 3-methyl 2-cyano-1,4-dihydro-6-methyl-4-(m-nitrophenyl)-3,5-pyridinedicarboxylate (nilvadipine, FR 34235, FK 235) on the cardiovascular system were investigated in isolated organs and whole animals. 1. Nilvadipine inhibited Ca2+-induced contractions of isolated dog coronary artery in high-K+, Ca2+-free medium, and the pA2 value was 10.64. In this effect, nilvadipine was 18 times more potent than nifedipine and 525 times more potent than diltiazem. In contrast, its inhibitory effect on Ca2+-induced contractions of isolated guinea pig atria was weaker (pA2:8.2): only twice that of nifedipine and 25 times that of diltiazem. 2. Nilvadipine also inhibited K+-induced 45Ca2+ uptake in isolated dog coronary arteries and isolated guinea pig atria. In the coronary arteries, the IC50 value of nilvadipine was 2.7 x 10(-10) mol/l, which was, respectively 17, 8, and 589 times lower than that of nifedipine, nicardipine and diltiazem. In the atria, on the other hand, the IC50 value of nilvadipine was 4.4 x 10(-9) mol/l, almost the same as that of nifedipine or nicardipine, and 47 times lower than that of diltiazem. These 45Ca2+ uptake inhibitory effects of the drugs were consistent with their effects on mechanical response in both tissues. 3. Nilvadipine (2.6 x 10(-10) mol/l and higher) dose-dependently inhibited ergometrine (ergonovine)-, serotonin-, and norepinephrine-induced contractions of isolated dog coronary artery, and its effects were 2 to 450 times more potent than those of nifedipine, nicardipine and diltiazem. 4. Nilvadipine (2.6 x 10(-8) mol/l or more, 32 micrograms/heart or more), like nifedipine, produced negative inotropic and chronotropic effects in isolated guinea pig atria and in dog heart-lung preparation, and was more potent than nifedipine in the negative chronotropic effect. 5. Nilvadipine in intravenous doses of 1-32 micrograms/kg decreased total peripheral resistance and systemic blood pressure, and slightly increased cardiac output, pulmonary arterial blood flow and stroke volume, but had no significant effects on pulmonary vascular resistance or pulmonary arterial blood pressure. Heart rate decreased at doses of 32 micrograms/kg or more. Nifedipine had almost the same effects as nilvadipine on total peripheral resistance and blood pressure, but was more potent than nilvadipine in increasing effects on cardiac output, stroke volume and pulmonary arterial blood flow.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Ca-dependent and Ca-independent histamine release from mast cells induced by active components of compound 48/80.

Compound 48/80 and 14C-labelled compound 48/80 were synthesized, and fractionated by thin-layer chromatography into 14 components with various histamine-releasing activities and different Ca++ requirements for their actions. The histamine release induced from rat mast cells in vitro by the most active component, fraction D (molecular weight = 2280, a tridecamer composed of 13 monomer units), was greatly elevated by extracellular Ca++, and was partially reduced by pretreatment of the cells with dinitrophenylated Ascaris antiserum, an IgE. In contrast, the histamine release induced by fraction H (molecular weight = 1580, a nonamer composed of 9 monomer units), was higher in Ca-free medium than in Ca-containing medium, and partially suppressed by pretreatment of mast cells with neurotensin or substance P, both Ca-independent releasers. The binding potencies of the 14C-labelled components estimated at 4 degrees C in the presence of Ca++, where no degranulation of the cells occurs, generally paralleled their histamine-releasing activities. However, Ca++ was inhibitory for the binding of 14C-fraction H. The binding of fraction D to [3H]arachidonic-acid-preloaded mast cells induced a rapid accumulation of the labelled arachidonic acid into phosphatidic acid, phosphatidylinositol and phosphatidylcholine, with concomitant decrease of the labelled arachidonic acid from phosphatidylethanolamine prior to the detectable histamine release.

Animals↗
PubMed1986

Effect of the tridecamer of compound 48/80, a Ca2+-dependent histamine releaser, on phospholipid metabolism during the early stage of histamine release from rat mast cells.

When the tridecamer component of compound 48/80 (Fraction D, Fr.D), a Ca2+-dependent histamine releaser, was incubated with rat mast cells that had been prelabeled with [32P]phosphate, [3H]inositol or [3H]glycerol, it induced a rapid decrease in [32P]phosphatidylinositol-4,5-bisphosphate (PIP2) followed by increases of [3H]inositol-1,4,5-trisphosphate (Ins P3) and [3H]diacylglycerol during the 10 sec prior to detectable histamine release. Fr.D-induced changes of the metabolism of these compounds occurred even in the absence of Ca2+, but to a lesser extent than in the presence of Ca2+. In contrast, the accumulation of [3H]arachidonic acid into phosphatidylcholine (PC), phosphatidylinositol (PI) and phosphatidic acid (PA) in [3H]arachidonic acid-prelabeled mast cells was Ca2+-dependently stimulated by Fr.D with a concomitant decrease in [3H]phosphatidylethanolamine (PE). These Ca2+-dependent changes in PC and PE were not observed in mast cells preloaded with [32P]phosphate, while [32P]PI and [32P]PA increased Ca2+ independently. Fr.D also increased 45Ca2+ uptake by mast cells within 5 sec after the stimulation. These results indicate that Fr.D binding to mast cell Ca2+ independently induces rapid changes of PI cycle-related metabolism of plasma membrane components, while it also induces Ca2+-dependent accumulation of arachidonic acid into PC, PI and PA in association with the decrease of PE, which may be important during the latent period prior to the Ca2+-dependent release of histamine from Fr.D-stimulated mast cells.

Animals↗
PubMed1985

Histamine release induced from mast cells by active components of compound 48/80.

Compound 48/80 and 14C-labeled compound 48/80 were synthesized, and fractionated by thin-layer chromatography into 14 components (A-N) with various histamine releasing activities and different Ca2+ requirements for their actions. The histamine release induced from rat mast cells in vitro by the most active component, fraction D (molecular weight = 2280, a tridecamer composed of 13 monomer units), was greatly enhanced by extracellular Ca2+, and was partially reduced by pretreatment of the cells with dinitrophenylated ascaris antiserum, an IgE. In contrast, the histamine release induced by fraction H (molecular weight = 1580, a nonamer composed of 9 monomer units), was higher in Ca2+ -free medium than in Ca2+-containing medium, and was partially reduced by pretreatment of mast cells with neurotensin or substance P, Ca2+-independent releasers. Apparently both fractions D and H are useful reagents for investigating the role of Ca2+ in histamine release and releaser binding in mast cells.

Animals↗
PubMed1985

Binding of active components of compound 48/80 to rat peritoneal mast cells.

The binding characteristics of compound 48/80 were examined using rat mast cells and fractionated 14C-labeled compound 48/80 components at 4 degrees C in vitro where no degranulation of the cells occurred. The binding potencies of these components in the presence of Ca2+ generally paralleled their histamine releasing activities, except in the case of fractions G (decamer) and H (nonamer), both Ca2+-independent releasers, for the binding of which Ca2+ was inhibitory. Scatchard analyses and displacement studies indicated that the mast cells had two types of binding sites with high and low affinities for fractions D (tridecamer, Ca2+-dependent releaser, Kd = 3.41 X 10(-8) M and 3.35 X 10(-6) M) and H (Ca2+-independent releaser, Kd = 1.11 X 10(-7) M and 9.11 X 10(-6) M), respectively. These sites partially overlapped each other, and also the fraction D site partially overlapped the IgE site and the fraction H site overlapped the neurotensin or substance P site.

Animals↗
PubMedDate not supplied

The effect of mass screening by physical examination combined with regular breast self-examination on clinical stage and course of Japanese women with breast cancer.

A mass screening program for breast cancer in Japan consists of physical examination (PE) and education on regular breast self-examination (BSE). The effect of PE with BSE on clinical stages and courses of breast cancer patients were retrospectively analyzed. Clinical stages and courses were compared between; i) patients who were examined in outpatient clinics (OPC, n=587), ii) patients who were detected by mass screening with regular BSE [BSE(+), n=68], and iii) without BSE [BSE(-), n=178]. Clinical stage in BSE(+) was significantly earlier than that in BSE(-) or OPC. As early stage cancer was most common in BSE(+), conservative surgery was mostly selected. Survival curve in BSE(+) was significantly better than those in BSE(-) or OPC. BSE complements the role of mass screening by PE for early detection and a more favorable clinical course.

Breast Neoplasms↗
PubMedDate not supplied

Local resection after breast-conserving therapy.

We analyzed the results of local re-excision after radiation therapy on seven patients with positive surgical margins at the initial breast-conserving surgery. The age of the patients ranged from 30 to 55 years, and the tumor sizes from 1.1 to 4.7 cm. Both estrogen receptor and progesterone receptor status were positive in two patients, negative in four, and unknown in one. Pathological examination revealed residual carcinoma in one (14.3%) of seven patients. The immunohistochemical results of the initial specimen were estrogen receptor-positive, c-erbB-2-positive, and Bax-negative. We performed local re-excision after radiation therapy and found only one incidence of residual carcinoma in the conserved breast.

Adult↗
PubMedDate not supplied

Regulation of estrogen receptor and epidermal growth factor receptor by tamoxifen under high and low estrogen environments in MCF-7 cells grown in athymic mice.

The purpose of this study was to investigate whether tamoxifen (TAM) treatment causes a downregulation of estrogen receptor (ER) and whether TAM induces epidermal growth factor receptor-1 (EGFR). We investigated the expression of ER and EGFR after the treatment of TAM in MCF-7 tumors grown in athymic mice under high and low estrogen environments. MCF-7 tumors were grown in ovariectomized athymic mice by implanting a sustained release 17beta-estradiol (E2) pellet. The E2 pellets were removed after 3 weeks of E2 treatment. Animals were then divided into the following 4 groups: i) an E2 (0. 72 mg/pellet) pellet [E2(+)]; ii) an E2 and a TAM (5 mg/pellet) pellets [E2(+)TAM]; iii) no treatment [E2(-)]; iv) a TAM pellet [E2(-)TAM]. A significant reduction in tumor size was observed in the estrogen-depleted group [E2(-) and E2(-)TAM] compared with the estrogen-completed group [E2(+) and E2(+)TAM]. TAM inhibited estrogen-stimulated growth in the estrogen-completed mice. No additional reduction of the tumor by TAM was observed in the estrogen-depleted mice. Both ER and EGFR protein levels in the tumors of the estrogen-depleted mice were higher than in the estrogen-completed mice. Expression of ER and EGFR protein was increased by TAM in the estrogen-completed mice, however it was decreased by TAM in the estrogen-depleted mice. Changes of ER and EGFR protein levels were similar in all treatments. Transforming growth factor-alpha (TGF-alpha) in tumors, which is known as a ligand of EGFR and as an estrogen-inducible protein in ER positive MCF-7 cells, was decreased by TAM in the estrogen-completed mice, by contrast, it was increased by TAM in the estrogen-depleted mice. Downregulation of ER was observed in TAM-treated mice in an estrogen-depleted environment, this action of TAM was similar to E2. These results suggest that increase of EGFR expression does not lead to a loss of ER after short-term TAM treatment in MCF-7 tumors.

Animals↗
PubMedDate not supplied

Immunohistochemical study on primary and recurrent tumors in patients with local recurrence in the conserved breast.

One hundred and seventy patients received breast-conserving therapy in the Second Department of Surgery, Gunma University School of Medicine. Six (3.5%) out of the 170 patients showed breast recurrence. We investigated the breast recurrent cases clinicopathologically. The age at the initial operation ranged from 38 to 78 (mean 57) years. One patient was clinical stage I and the others were clinical stage II. Surgical margin at the initial operation was negative in two patients and positive in four. Histological type was invasive ductal cancer in all cases. Three patients had lymph node involvement. The interval from the initial operation to breast recurrence ranged from 19 to 68 months. Five cases were nodular type and one was diffuse type of breast recurrence. Histological type of breast recurrence was the same as the initial one. We performed salvage surgery for all breast recurrent patients, mastectomy for four patients and local resection for two. One patient who showed diffuse type of recurrence could not be controlled with any surgical treatment, and later died of breast cancer. We investigated the expression of estrogen receptor, progesterone receptor, pS2, c-erbB-2 and p53 on both initial and recurrent specimens of the six patients. The expression of each protein on the recurrent specimens was the same as the initial one. We conclude that breast recurrence after breast-conserving therapy has its origin in the residue of cancer cells at the initial operation, even if surgical margins are histopathologically negative.

Adult↗
PubMedDate not supplied

Serum concentration of pyridinoline cross-linked carboxyterminal telopeptide of type I collagen in patients with metastatic breast cancer.

The serum concentration of pyridinoline cross-linked carboxyterminal telopeptide of type I collagen (ICTP) was examined in 83 patients with metastatic breast cancer. ICTP levels were significantly higher in patients with bone metastases than in those without bone metastasis. In patients with bone metastasis, significantly higher ICTP levels were observed in those with multiple lesions than in those with a solitary lesion and these levels reflected therapeutic response. Sequential monitoring of ICTP revealed that this elevation was correlated with disease progression. Combined with imaging studies, monitoring of ICTP appears to offer additional information for detection of bone metastasis and evaluation of therapeutic response to bone metastasis.

Adult↗
PubMedDate not supplied

Effect of a combined administration of 5-fluorouracil and medroxyprogesterone acetate on pyrimidine nucleoside phosphorylases and thymidylate synthetase in 7,12-dimethylbenz.

The effect of a combined therapy of medroxyprogesterone acetate (MPA) and 5-fluorouracil (5-FU) on tumor size, pyrimidine nucleoside phosphorylase (PyNPase) activity, and thymidylate synthetase (TS) activity was examined in Sprague-Dawley (SD) rats with 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary tumors. MPA augmented the antitumor activity of 5-FU and protected against body weight-loss due to 5-FU administration. PyNPase activity of both the MPA group and the MPA+5-FU group tended to increase compared with that of the 5-FU alone group. TS inhibition levels in the MPA+5-FU group tended to increase compared with those in the 5-FU alone group. These results indicate that MPA tended to augment antitumor activity of 5-FU and to reduce the side effects caused by 5-FU.

9,10-Dimethyl-1,2-benzanthracene↗