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Y Koibuchi

Publications and source records attributed to Y Koibuchi.

At least 37 records · Page 2Linked to original sources
PubMed1999

Mitogen-activated protein kinase cascade in breast cancer.

The mitogen-activated protein (MAP) kinase is considered to play a central role in diverse cellular events including carcinogenesis and tumor progression. Indeed, expression of MAP kinase, tyrosine-phosphorylated MAP kinase, and Raf-1 protein was greater in cancerous human tissues than in the surrounding noncancerous glands. In a 7,12-dimethylbenz[a]anthracene-induced rat mammary carcinoma model, estrogen promoted and ovariectomy and antiestrogen, tamoxifen (TAM) inhibited the tumor growth. Ovariectomy suppressed expression of MAP kinase, tyrosine-phosphorylated MAP kinase and Raf-1, whereas estrogen as well as TAM induced expression of MAP kinase and Raf-1 under castrated conditions. Since it was reported that MAP kinase was activated during the progression of breast carcinoma cells, such estrogenic actions of TAM toward the MAP kinase cascade might be responsible for malignant progression.

Animals↗
PubMed1999

The mechanisms of antitumor effects of luteinizing hormone-releasing hormone agonist (buserelin) in 7, 12-dimethylbenz(a)anthracene-induced rat mammary cancer.

We evaluated the mechanism of antitumor effects of buserelin, which is one of LH-RH agonists, on a hormone dependent breast cancer model, using 7,12-dimethylbenz(a)anthracene (DMBA)-induced rat mammary cancer. Rats developing solid mammary tumors within 5-7 weeks following the DMBA administration were divided into groups weekly, and treated without delay. The tumor bearing rats were randomized into five groups with regard to tumor size or average weight (15 rats per group). Each group received one of the following treatments during 4 weeks: a) no treatment (NT); b) ovariectomy (Ovx); c) buserelin; d) Ovx and 17beta-estradiol (E2) (Ovx+E2); e) Ovx+E2+buserelin. Tumor regression immediately began at one week after both buserelin treatment and ovariectomy. A significant reduction of tumor size was observed in both buserelin-treated rats and Ovx rats compared with NT rats (p<0.01). No significant difference of tumor size was observed between buserelin-treated rats and ovariectomized rats. No reduction of tumor size was observed in Ovx+E2 rats and Ovx+E2+buserelin rats. Although the mean uterine wet weight of the buserelin group was significantly higher than that of the Ovx group, it was significantly lower than that of the NT group. The mean uterine wet weight of the NT group, the Ovx+E2 group and the Ovx+E2+buserelin group was similar and was significantly higher than that of the Ovx group. Buserelin did not inhibit exogenous estrogen-dependent tumor growth in DMBA-induced rat mammary cancers. These results suggest that buserelin has no direct effects on DMBA-induced rat mammary cancers, and the main mechanism of action of buserelin for tumor-reduction is due to ovarian estrogen deficiency.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1999

Expression and possible functional role of the beta3-adrenoceptor in human and rat detrusor muscle.

PURPOSE: To investigate the presence of the beta3-adrenoceptor (beta3-AR) in human and rat detrusor muscle and the usefulness of beta3-AR agonists as drugs for the treatment of urinary frequency. MATERIALS AND METHODS: FK175, ethyl [(S)-8-[(R)-2-(3-chlorophenyl)-2-hydroxyethylamino]-6,7,8,9-tetrah ydro-5H-benzocyclohepton-2-yloxy]acetate monohydrochloride monohydrate, was used as a beta3-AR selective agonist. The expression of beta-AR subtypes (beta1-, beta2-, beta3-AR) mRNA was investigated in rat and human detrusor muscle by RT-PCR. Beta3-AR agonist induced cyclic AMP (cAMP) levels were measured in rat detrusor muscle strips. The relaxation response produced by a beta3-AR agonist was measured in a KCl induced tonic contraction model in rat detrusor muscle strips. The effect of a beta3-AR agonist on urinary bladder function was investigated by cystometry using a conscious rat model of urinary frequency. RESULTS: beta3-AR mRNA was substantially expressed in both rat and human detrusor muscles. The beta3-AR agonist, FK175 (10(-7) M), increased the cAMP level by 30% in rat detrusor muscle. In isolated rat detrusor muscle strips contracted with KCl, the beta3-AR agonist, FK175 (10(-8) to 10(-4) M), produced a concentration-dependent relaxation. Moreover, although the relaxation induced with FK175 was blocked by the non-selective beta-AR antagonist, bupranolol, it was unaffected by ether the beta1-AR selective antagonist, CGP 20712A, or the beta2-AR selective antagonist, ICI 118551, suggesting that FK175 induced the relaxation via the beta3-AR. Furthermore, in the rat model, the orally administered beta3-AR agonist, FK175 (10 mg./kg.) significantly increased bladder capacity with no change of micturition pressure or threshold pressure. CONCLUSIONS: These results suggest that beta3-AR agonists may be effective in the treatment of urinary frequency.

Adrenergic beta-Agonists↗
PubMed1999

A novel aromatase inhibitor, vorozole, shows antitumor activity and a decrease of tissue insulin-like growth factor-I level in 7, 12-dimethylbenz[a]anthracene-induced rat mammary tumors.

Effects of vorozole, a potent and specific non-steroidal aromatase inhibitor, were evaluated on female Sprague-Dawley (SD) rats with 7, 12-dimethylbenz[a]anthracene (DMBA)-induced mammary tumors. Vorozole at a dose of 0.25, 1.0 and 4.0 mg/kg was orally administered once a day for 28 consecutive days. A significant regression in tumor size was observed in each treated group at 1, 2, 3 and 4 weeks after the start of treatment compared with control group. Tissue insulin-like growth factor I (IGF-I) in the DMBA-induced tumors in each treated group significantly decreased in a dose-dependent fashion compared with control group. These results show the mechanism of vorozole in DMBA-induced rat mammary tumors.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1998

Serum concentration of hepatocyte growth factor in patients with metastatic breast cancer.

The serum concentration of hepatocyte growth factor (HGF) was examined in 34 patients with metastatic breast cancer. Although no significant difference was observed between HGF concentration and the site of metastasis, serum HGF levels were slightly higher in patients with liver metastasis and in patients with multiple metastatic sites than in patients with other lesions. Significantly higher levels of serum HGF were observed in patients with progressive metastasis of breast cancer compared with those with stable metastasis. The patients with high HGF levels exhibited a significantly shorter survival rate than those with low HGF levels. Circulating HGF levels may be a useful indicator for the progression of metastatic lesions and the prognosis of patients with metastatic breast cancer.

Adult↗
PubMed1998

Angiogenesis and stromal fibronectin expression in invasive breast carcinoma.

Angiogenesis and stromal fibronectin (SFN) expression were immunohistochemically analyzed in 83 breast cancer specimens. Microvessel count (MVC), which correlated with lymph node metastasis, TNM stage, recurrence, and mortality, was relatively low in SFN-positive tumors. SFN expression did not correlate with lymph node metastases or tumor size. However, SFN positivity was less likely in patients with recurrent disease than in those without recurrence, and relapse-free survival was significantly better in patients with SFN-positive tumors than in those with SFN-negative tumors. MVC and SFN positivity were significant independent predictors of relapse-free survival as well as tumor size and axillary nodal status (Cox's proportional hazards regression analysis). Angiogenesis and SFN expression, both of which are inversely related, can be used prognostically in patients with breast cancer.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1998

Inhibitory effects of an antiestrogen, toremifene, on the phorbol ester-induced adhesive capacity of breast carcinoma cells.

Previous studies have revealed that protein kinase C (PKC) is responsible for malignant progression. In the present study, we investigated the potent inhibitory effects of an antiestrogen, toremifene, on PKC-mediated cellular adhesion. A phorbol ester, phorbol 12-myristate 13-acetate (PMA), significantly enhanced alpha2beta1 integrin-dependent adhesion of MCF-7 breast carcinoma cells. This PMA-induced adhesion was partially inhibited by incubating cells with toremifene prior to PMA exposure in a time- and dose-dependent manner. FACS analysis demonstrated that the PMA-induced alpha2beta1-dependent cellular adhesion was accompanied with elevated expression of alpha2beta1+integrin subunit on the cell surface. However, toremifene did not affect the elevated expression levels of these integrins but rather the avidity of alpha2beta1 integrin. We concluded that toremifene inhibited cellular adhesion activated by PMA, probably through mechanism which inhibits PKC.

Breast Neoplasms↗
PubMed1998

[Genetic testing for ret mutation for early diagnosis and treatment in familial medullary thyroid carcinoma: a case report].

A 13-year-old girl and her older sister were referred to our hospital because her father and another older sister and been suffering from medullary thyroid carcinoma (MTC). Physical examinations revealed no thyroid mass. Ultrasonography (US) detected a small hypoechoic lesion in the right thyroid lobe, 3 mm in size. The serum calcitonin level was slightly elevated for their age. One and half year later, US finding showed a slightly larger mass, 7 mm in size, which was not palpable. Genetic testing for ret protooncogene mutation revealed a point mutation at codon 634 (Cys-->Arg) in exon 11. Surgical treatment was recommended, however, the patient wanted to receive it only after the admission to senior high school. Her sister had no mutation in ret protooncogene. The patient underwent total thyroidectomy with modified neck dissection at 16 years of age. At that time, a new mass emerged in the left thyroid lobe and the serum calcitonin level increased to 171 pg/ml. MTC was found in each lobe with positive staining of CEA and carcitonin. No lymph node metasis was found. Her postoperative course was uneventful. Genetic testing for ret mutation is effective for early diagnosis and treatment of patient with FMTC, and is recommended as standard management for hereditary MTC in affected families.

Adolescent↗
PubMed1995

Pneumocystis carinii pneumonia during treatment for recurrent breast cancer: a case report.

We describe a case of Pneumocystis carinii pneumonia (PCP) in a woman with recurrent breast cancer without human immunodeficiency virus (HIV) infection. The PCP was associated with severe lymphocytopenia due to treatment with anticancer agents in combination with granulocyte colony-stimulating factor (G-CSF). Despite the severe lymphocytopenia, the total leucocyte count never fell below 3000/mm3 during the treatment. It was difficult to determine whether the patient's respiratory failure was caused by severe infectious pneumonia, hypersensitivity pneumonia or pneumonitis carcinomatosis. She was treated with steroid for suspected drug-induced hypersensitivity pneumonia. However, as her condition did not improve, PCP was suspected, and sulfamethoxazole-trimethoprim was administered. At the same time, anticancer drugs were administered to half the progression of the cancer, since lymphangitis carcinomatosa was also suspected. The severe respiratory failure did not improve, and the patient died on day 23 after admission. At autopsy, the cause of death was confirmed to respiratory failure due to PCP.

Adult↗
PubMed1995

Effects of vamicamide on urinary bladder functions in conscious dog and rat models of urinary frequency.

PURPOSE: To investigate the usefulness of vamicamide, (+/-)-(2R*, 4R*)-4-dimethylamino-2-phenyl-2-(2-pyridyl)valeramide, as a novel drug for the treatment of urinary frequency and incontinence. MATERIALS AND METHODS: Urinary frequency was evaluated in specially devised conscious dog and rat models by investigating the effects of the drug on urinary bladder function of these animals by cystometrography. RESULTS: In the dog model with transected hypogastric nerves, the bladder volume at micturition (bladder capacity) was less than 50% that of the sham-operated dog, and in the rat model with bilateral lesioning of nuclei basalis, a part of the brain, by ibotenic acid injection, bladder capacity was about 50% that of the sham-operated rat. Other bladder functions in both models were unchanged. In the dog model, orally administered vamicamide at 0.32 and 1.0 mg./kg. significantly increased bladder capacity and did not change residual urine volume or micturition pressure. Oxybutynin 0.10 mg./kg., one of the most popular drugs for the treatment of urinary frequency and incontinence, or atropine 0.10 mg./kg. induced significant increases in bladder capacity similarly to vamicamide at 0.32 mg./kg. In the rat model, oral vamicamide 0.32 mg./kg. also significantly increased bladder capacity and did not change micturition pressure or threshold pressure. Again, oxybutynin 0.10 mg./kg. or atropine 0.32 mg./kg. had almost the same effects as vamicamide 0.32 mg./kg. CONCLUSIONS: These findings suggest that vamicamide should be useful for the treatment of urinary frequency.

Animals↗
PubMed1995

Fibromatosis of the breast: a case report.

Fibromatosis of the female breast is rare. We dealt with a recurrent case of fibromatosis four months after a wide excision of the tumor. It was difficult to differentiate the tumor from carcinoma and only a pathological examination could lead to the final diagnosis. Ultrasonographic findings are so characteristic that we would like to emphasize the usefulness of ultrasonography not only in distinguishing between recurrence and operative scar but also in defining the diagnosis as fibromatosis of the breast.

Adult↗
PubMed1995

Malignant rhabdoid tumor of the breast: a case report.

A 66-year-old woman developed a malignant rhabdoid tumor of the breast, with a tumor doubling time of 10 days. One month after radical mastectomy, there was local recurrence, followed by multiple pulmonary metastases, and the patient died of respiratory failure 5 months after surgery. The gray-white-colored tumor measured 13 x 12 x 10 cm, and its border was well defined. The tumor was composed of diffusely growing round or polygonal cells with vesicular nuclei, prominent nucleoli, and ample cytoplasm containing eosinophilic inclusions. Lymph node involvement was widespread. Both vimentin and keratin were clearly demonstrated by immunohistochemical staining. Ultrastructural studies revealed that the MRT cells contained cytoplasmic whorls of intermediate filaments.

Aged↗
PubMed1994

Tolerance to the vascular effect of a novel nitric oxide-donating vasodilator, FK409.

We investigated whether tolerance develops to the vasorelaxant effects of a new vasodilator, (+-)-(E)-4-ethyl-2-[(E)-hydroxy-imino]-5-nitro-3-hexenamide (FK409), in isolated canine coronary artery strips and to its hypotensive effect in rats, and whether FK409 activates soluble guanylate cyclase isolated from vascular tissues in the absence of L-cysteine. No tolerance to FK409 (0.46 nM to 0.46 microM or 1-1000 micrograms/kg, i.v.) or cross-tolerance between FK409 and glyceryl trinitrate was demonstrated in in vitro and in vivo experiments, whereas the tolerance to glyceryl trinitrate (0.44 nM to 4.4 microM or 1-1000 micrograms/kg, i.v.) was marked in both conditions. In addition, FK409 (0.1-10 microM) activated soluble guanylate cyclase without L-cysteine, but glyceryl trinitrate (1-100 microM) required the addition of L-cysteine (5 mM) for the activation of the enzyme. The results suggest that FK409 may be advantageous compared to tolerance-producing nitrates currently in clinical use, and that this property of FK409 is probably due to its independence of a sulfhydryl group donor.

Animals↗
PubMed1993

Vasorelaxant mechanism of the new vasodilator, FK409.

To define the vasorelaxation mechanism of FK409, we examined the effect of the compound on vascular tension and cyclic nucleotide levels in isolated rat thoracic aorta contracted with norepinephrine, and on activities of guanylate cyclase and cyclic GMP phosphodiesterase prepared from rat or rabbit thoracic aorta. FK409 (1 x 10(-9) to 1 x 10(-6) M), like nitroglycerin (1 x 10(-9) to 1 x 10(-6) M), produced a potent vasorelaxant effect associated with an increase in cyclic GMP content of the tissue. There was no change in cyclic AMP levels. The vasorelaxant effect of FK409 was independent of the integrity of the endothelium, and was unaffected by L-NG-monomethylarginine (0.1 mM) or oxyhemoglobin (1 microM). On the other hand, FK409 (3.2 x 10(-7) M) activated soluble guanylate cyclase, and the activating effect was completely inhibited by oxyhemoglobin (10 nM). Cyclic GMP phosphodiesterase was unaffected by FK409 (1 x 10(-7) to 1 x 10(-5) M). Furthermore, in rat aortic soluble fraction FK409 (3 mM) was found to liberate nitric oxide (NO) which was evaluated spectrophotometrically after diazotization of sulfanilic acid and coupling with N-(1-naphthyl)-ethylenediamine. The liberation occurred even in the absence of L-cysteine (5 mM), in contrast to the case with nitroglycerin (3 mM). These results suggest that the vasorelaxant effect of FK409 is associated with an increase in intracellular cyclic GMP, and that the cyclic GMP accumulation is due to activation of soluble guanylate cyclase. The enzyme activation is probably due to NO released from the compound molecule in the vascular smooth muscle cells.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1993

Role of transforming growth factor-beta 1 in the cellular growth response to angiotensin II.

We have shown that angiotensin II (Ang II)-induced hypertrophy of vascular smooth muscle cells is dependent on the balance between proliferative and antiproliferative growth factors, specifically basic fibroblast growth factor and transforming growth factor-beta 1 (TGF-beta 1), respectively. We now present evidence, based on two phenotypically distinct cell cultures, that the ability to secrete the biologically active form of TGF-beta 1 is central to the growth response to Ang II. Two separate cultures were examined, one in which Ang II induces hypertrophy and the other in which Ang II induces hyperplasia. Ang II induces the expression of basic fibroblast growth factor twofold to fivefold in both cultures. Furthermore, both cultures express TGF-beta 1. In the culture that responds with hypertrophy, Ang II induces the expression of the active form of TGF-beta 1 twofold to threefold. However, in the culture that responds with hyperplasia, no active TGF-beta 1 was detected either at baseline or after Ang II exposure. Interestingly, all the TGF-beta 1 present was in the inactive, latent form. In the culture that responded with hyperplasia, Ang II induced a fourfold to fivefold increase in DNA synthesis. This increase could be abolished by the addition of active TGF-beta 1. Thus in these two cultures the ability to activate TGF-beta 1 dictates the cellular response to Ang II. These results support our hypothesis that a balance of proliferative and antiproliferative autocrine signals mediates the growth control of vascular smooth muscle cells.

Angiotensin II↗
PubMed1993

Lack of stereoselectivity in rat liver peroxisomal enzyme induction by optically active phenoxyacetic acids.

To ascertain if there is stereoselectivity in peroxisomal proliferation induced by chiral peroxisome proliferators, induction by stereoisomers of 2-methyl-4'-chlorophenoxyacetic acid and 2-methyl-2-(2'-4'-dichlorophenoxy)acetic acid were studied in rat in vivo and in vitro with isolated rat hepatocytes. No significant differences in the inducing potencies of the stereoisomers of the above two phenoxyacetic acid derivatives were found for cyanide-insensitive fatty acyl-CoA oxidizing system, fatty acyl-CoA oxidase, carnitine acetyltransferase or carnitine palmitoyltransferase. There was also no significant difference in the degree of hepatomegaly or lipid-lowering effect between the isomers. The findings with cultured rat hepatocytes agreed with those of the studies in vivo.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1993

Effect of FK409, a novel nitric oxide donor, on acute experimental myocardial ischemia.

The anti-ischemic heart effect of (+/-)-(E)-4-ethyl-2-[(E)-hydroxyimino]- 5-nitro-3-hexenamide (FK409), a novel nitric oxide donor, was studied in dog and rat preparations in vivo and in vitro. In anesthetized dogs with partially occluded coronary artery that were subjected to atrial pacing at a constant blood pressure, FK409 (1-100 micrograms/kg, i.v.) suppressed the ST-segment elevation on epicardial electrocardiograms. Glyceryl trinitrate (GTN; 10, 32 micrograms/kg) or dipyridamole (1000 micrograms/kg) failed to suppress the ST-segment elevation, although continuous i.v. infusion of GTN (32, 100 micrograms/kg/min) was effective. FK409 also suppressed the ST-segment elevation induced by methacholine in anesthetized rats by both i.v. (10, 100 micrograms/kg) and intraduodenal (i.d., 100, 1000 micrograms/kg) injections, while GTN (100 micrograms/kg, i.v.; 1000 micrograms/kg, i.d.) was effective only by the i.v. route. FK409 (0.32 microgram/kg/min, i.v.) and GTN (10 micrograms/kg/min) increased the blood flows of the endomyocardium (ENDO) and the epicardium (EPI) and the flow ratio of ENDO/EPI in the ischemic zone in anesthetized dogs with occluded coronary artery. Furthermore, in isolated dog vascular preparations, FK409 (4.6 x 10(-10)-4.6 x 10(-7) M) had a greater vasorelaxing effect on the large coronary artery [2.0-2.5-mm outer diameter (od)] than on the small coronary artery (0.3-0.5-mm od) or the saphenous artery. The results suggest that FK409 protects against acute experimental myocardial ischemia through relaxation of the large conductive coronary artery, and may be a useful oral drug for the treatment of angina pectoris.

Animals↗