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Kojima T, Asano Y, Kurasawa O, Hirata Y, Iwamura N, Wong TT, Saito B, Tanaka Y, Arai R, Yonemori K, Miyamoto Y, Sagiya Y, Yaguchi M, Shibata S, Mizutani A, Sano O, Adachi R, Satomi Y, Hirayama M, Aoyama K, Hiura Y, Kiba A, Kitamura S, Imamura S. Discovery of novel serine palmitoyltransferase inhibitors as cancer therapeutic agents. Bioorg Med Chem 2018; 26:2452-2465. [PMID: 29669694 DOI: 10.1016/j.bmc.2018.04.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Revised: 04/03/2018] [Accepted: 04/03/2018] [Indexed: 12/18/2022]
Abstract
We pursued serine palmitoyltransferase (SPT) inhibitors as novel cancer therapeutic agents based on a correlation between SPT inhibition and growth suppression of cancer cells. High-throughput screening and medicinal chemistry efforts led to the identification of structurally diverse SPT inhibitors 4 and 5. Both compounds potently inhibited SPT enzyme and decreased intracellular ceramide content. In addition, they suppressed cell growth of human lung adenocarcinoma HCC4006 and acute promyelocytic leukemia PL-21, and displayed good pharmacokinetic profiles. Reduction of 3-ketodihydrosphingosine, the direct downstream product of SPT, was confirmed under in vivo settings after oral administration of compounds 4 and 5. Their anti-tumor efficacy was observed in a PL-21 xenograft mouse model. These results suggested that SPT inhibitors might have potential to be effective cancer therapeutics.
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Affiliation(s)
- Takuto Kojima
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-0012, Japan.
| | - Yasutomi Asano
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-0012, Japan
| | - Osamu Kurasawa
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-0012, Japan
| | - Yasuhiro Hirata
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-0012, Japan
| | - Naoki Iwamura
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-0012, Japan
| | - Tzu-Tshin Wong
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-0012, Japan
| | - Bunnai Saito
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-0012, Japan
| | - Yuta Tanaka
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-0012, Japan
| | - Ryosuke Arai
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-0012, Japan
| | - Kazuko Yonemori
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-0012, Japan
| | - Yasufumi Miyamoto
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-0012, Japan
| | - Yoji Sagiya
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-0012, Japan
| | - Masahiro Yaguchi
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-0012, Japan
| | - Sachio Shibata
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-0012, Japan
| | - Akio Mizutani
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-0012, Japan
| | - Osamu Sano
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-0012, Japan
| | - Ryutaro Adachi
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-0012, Japan
| | - Yoshinori Satomi
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-0012, Japan
| | - Megumi Hirayama
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-0012, Japan
| | - Kazunobu Aoyama
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-0012, Japan
| | - Yuto Hiura
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-0012, Japan
| | - Atsushi Kiba
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-0012, Japan
| | - Shuji Kitamura
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-0012, Japan
| | - Shinichi Imamura
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-0012, Japan.
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Ono K, Banno H, Okaniwa M, Hirayama T, Iwamura N, Hikichi Y, Murai S, Hasegawa M, Hasegawa Y, Yonemori K, Hata A, Aoyama K, Cary DR. Design and synthesis of selective CDK8/19 dual inhibitors: Discovery of 4,5-dihydrothieno[3′,4′:3,4]benzo[1,2- d ]isothiazole derivatives. Bioorg Med Chem 2017; 25:2336-2350. [DOI: 10.1016/j.bmc.2017.02.038] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 02/17/2017] [Accepted: 02/17/2017] [Indexed: 12/29/2022]
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Fukumori S, Tsuji Y, Mizoguchi A, Kasai H, Ishibashi T, Iwamura N, To H. Association of the clinical efficacy of vancomycin with the novel pharmacokinetic parameter area under the trough level (AUTL) in elderly patients with hospital-acquired pneumonia. J Clin Pharm Ther 2016; 41:399-402. [PMID: 27144370 DOI: 10.1111/jcpt.12399] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 04/08/2016] [Indexed: 11/30/2022]
Abstract
WHAT IS KNOWN AND OBJECTIVE The pharmacokinetic-pharmacodynamic parameter that best predicts the efficacy of vancomycin is the ratio of the area under the concentration versus time curve (AUC) to the minimum inhibitory concentration (MIC). A 24-h AUC (AUC24 )/MIC ratio ≥ 400 was recommended in an American consensus review, but vancomycin treatment occasionally fails despite maintenance of AUC24 /MIC ≥ 400. We evaluated the association between clinical efficacy of vancomycin and two novel pharmacokinetic parameters, the 'area under the trough level' (AUTL) and the 'area above the trough level' (AATL), in hospitalized elderly patients with methicillin-resistant Staphylococcus aureus (MRSA) pneumonia. METHODS The subjects were hospitalized elderly patients who were administered vancomycin for treatment of MRSA pneumonia between 2006 and 2012 at Sasebo Chuo Hospital (Nagasaki, Japan). Pharmacokinetic parameters of vancomycin were estimated for each patient by Bayesian analysis using population pharmacokinetic parameters for Japanese patients. Based on the patient-specific parameters thus obtained, AUC24 values were calculated as the vancomycin dosage divided by vancomycin clearance. AUTL was calculated as the trough serum concentration multiplied by 24 h, whereas AATL was calculated by subtracting AUTL from AUC24 . RESULTS AND DISCUSSION Logistic regression analysis demonstrated that efficacy of vancomycin was more strongly associated with AUTL than AUC24 . The optimal cut-off value of AUTL was 331 μg∙h/mL, which means that the optimal cut-off value of the trough serum concentration was 13·8 μg/mL. WHAT IS NEW AND CONCLUSION Efficacy of vancomycin was associated with AUTL, a novel pharmacokinetic parameter. Determining the target AUTL or trough concentration may enhance the efficacy of vancomycin therapy in elderly patients with MRSA pneumonia. Given that nephrotoxicity may increase with a Ctrough in excess of 15 μg/mL, this level should ideally not be exceeded.
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Affiliation(s)
- S Fukumori
- Department of Community Pharmacy, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
| | - Y Tsuji
- Department of Medical Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
| | - A Mizoguchi
- Department of Pharmacy, Sasebo Chuo Hospital, Sasebo, Japan
| | - H Kasai
- Department of Medical Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan.,Certara G.K., Minato-ku, Tokyo, Japan
| | - T Ishibashi
- Department of Medical Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan.,Shionogi Research Laboratories, Osaka, Japan
| | - N Iwamura
- Department of Pharmacy, Sasebo Chuo Hospital, Sasebo, Japan
| | - H To
- Department of Medical Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
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Takahara S, Iwamura N, Ema Y, Sato Y, Mizukoshi M, Nagano T, Ichikuni N. Formation and dichroism of poly(vinyl alcohol)-iodine complex in photocurable film. POLYM ADVAN TECHNOL 2015. [DOI: 10.1002/pat.3457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Shigeru Takahara
- Department of Image and Materials Science, Graduate School of Advanced Integration Science; Chiba University; 1-33 Yayoi-cho, Inage-ku Chiba 263-8522 Japan
| | - Naoki Iwamura
- Department of Image and Materials Science, Graduate School of Advanced Integration Science; Chiba University; 1-33 Yayoi-cho, Inage-ku Chiba 263-8522 Japan
| | - Yusuke Ema
- Department of Image and Materials Science, Graduate School of Advanced Integration Science; Chiba University; 1-33 Yayoi-cho, Inage-ku Chiba 263-8522 Japan
| | - Yusuke Sato
- Department of Image and Materials Science, Graduate School of Advanced Integration Science; Chiba University; 1-33 Yayoi-cho, Inage-ku Chiba 263-8522 Japan
| | - Masanori Mizukoshi
- Department of Image and Materials Science, Graduate School of Advanced Integration Science; Chiba University; 1-33 Yayoi-cho, Inage-ku Chiba 263-8522 Japan
| | - Tomoki Nagano
- Department of Image and Materials Science, Graduate School of Advanced Integration Science; Chiba University; 1-33 Yayoi-cho, Inage-ku Chiba 263-8522 Japan
| | - Nobuyuki Ichikuni
- Department of Applied Chemistry and Biotechnology, Graduate School of Engineering; Chiba University; 1-33 Yayoi-cho, Inage-ku Chiba 263-8522 Japan
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Shionozaki N, Iwamura N, Tanaka R, Makino K, Uchiro H. Total synthesis of diaporthichalasin by using the intramolecular Diels-Alder reaction of an α,β-unsaturated γ-hydroxylactam in aqueous media. Chem Asian J 2013; 8:1243-52. [PMID: 23554293 DOI: 10.1002/asia.201201230] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2012] [Indexed: 11/07/2022]
Abstract
The first total synthesis of diaporthichalasin has been successfully achieved and complete structure elucidation, including the absolute configuration, was also accomplished. The intramolecular Diels-Alder (IMDA) reaction between the diene side chain on the decalin skeleton and α,β-unsaturated γ-hydroxy-γ-lactam in aqueous media was effectively employed as the key step. From this synthetic study, we found that α,β-unsaturated γ-hydroxy-γ-lactam is an essential precursor for the construction of the diaporthichalasin-type pentacyclic skeleton. This important finding strongly suggests that this route is involved in the biosynthetic pathway for diaporthichalasin.
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Affiliation(s)
- Nobuhiro Shionozaki
- Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
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Uchiro H, Shionozaki N, Tanaka R, Kitano H, Iwamura N, Makino K. First total synthesis of oteromycin utilizing one-pot four-step cascade reaction strategy. Tetrahedron Lett 2013. [DOI: 10.1016/j.tetlet.2012.11.073] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Miyamoto T, Shiozawa K, Iwamura N, Nomura T, Fukasu H, Funato Y, Kobayashi Y, Miura T, Joshi YR, Shrestha PN, Pradhan I, Shrestha SB, Pradhan ML, Tandokar BB, Karki DB, Bhakia I. Tuberculosis Survey In Bhaktapur. JNMA J Nepal Med Assoc 2003. [DOI: 10.31729/jnma.906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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8
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Tamai H, Masago K, Chang K, Iwamura N, Ohkado S, Uchida K, Ohtsuji M, Chinzei M, Hanaoka K. [Anesthetic management for neonates with congenital cystic adenomatoid malformation]. Masui 2000; 49:750-4. [PMID: 10933026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
We experienced two cases of congenital cystic adenomatoid malformation (CCAM) diagnosed by prenatal ultrasonography. The first case with type I CCAM underwent the resection of the right upper lobe 8 days after birth. Postoperative course was uneventful. The second case with type III CCAM developed non-immune hydrops, severe mediastinal shift, and polyhydroamnios at 29 weeks' gestation. At 30 weeks' gestation, cesarean section was performed. Immediately after birth, the resection of lung tumor for the neonate was performed. However, the neonate died on the 1st postoperative day.
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Affiliation(s)
- H Tamai
- Department of Anesthesiology, Faculty of Medicine, University of Tokyo
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9
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Kishikawa H, Tsuji H, Takagi I, Yamakawa Y, Shimozato T, Honda K, Shibata A, Iwamura N. Hemorrhagic necrosis of pheochromocytoma associated with reversible renal artery stenosis. Jpn J Surg 1986; 16:46-51. [PMID: 3959360 DOI: 10.1007/bf02471069] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
An unusual case of pheochromocytoma associated with renal artery stenosis is described. Despite the removal of bilateral adrenal pheochromocytoma, laboratory findings suggested the presence of residual pheochromocytoma and abdominal aortography revealed more pronounced stenosis of the right renal artery. Two months later, the undetected residual pheochromocytoma underwent hemorrhagic necrosis with acute cessation of catecholamine release. Thereafter, the patient's blood pressure decreased to a normal level with marked improvement in hypertensive symptoms. No remaining stenosis was demonstrated on follow up renal angiography. Our case suggests that constant local secretion of catecholamines may be responsible for the development of renal artery stenosis.
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10
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Tsuboi S, Nakagawa T, Tomita M, Seo T, Ono H, Kawamura K, Iwamura N. Detection of aflatoxin B1 in serum samples of male Japanese subjects by radioimmunoassay and high-performance liquid chromatography. Cancer Res 1984; 44:1231-4. [PMID: 6420055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Aflatoxin B1 (AFB1) was detected in serum samples of healthy Japanese males by radioimmunoassay and high-performance liquid chromatography. Blood samples were obtained from 20 subjects after fasting and from 80 subjects after lunch. The subjects ranged in age from 20 to 63 years of age. Measurement of AFB1 in the samples was performed by radioimmunoassay and was confirmed by high-performance liquid chromatography using a mu Porasil column and a C18-mu Bondapak column after the conversion of AFB1 to its water adduct AFB2a. AFB1 was detected in 5 of 20 fasting blood samples [20 to 56 pg/ml of serum; 33.6 +/- 14.6 (S.D.)] and in 29 of 80 serum samples taken after lunch (20 to 1169 pg/ml of serum; 218.1 +/- 268.3). Mass spectral analysis of the material obtained after high-performance liquid chromatography separation from serum samples confirmed the presence of AFB1.
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Abstract
The possibility of cryopreserving the eggs of Angiostrongylus cantonensis collected from the uterus of female worms was investigated. Eggs were cultured in NCTC 109 medium containing 50% rat serum, and various growth stages, from one-cell eggs to embryonated eggs, were used in this study. As a cryoprotective agent, dimethylsulphoxide (Me2SO) was added to the medium at a final concentration of 1 M. Eggs suspended in 0.2 ml of the medium at 37 degrees C were cooled to 0 degrees C at a rate of 1 degree C min-1, then an equal volume of 2M-Me2SO solution was added. After equilibration for 15 min, the freezing procedures were started. In the freezing procedures, the effectiveness of (i) a seeding process, (ii) different cooling and warming rates and (iii) the relationship between the growth stages of the eggs and their tolerance to freezing at -20 degrees C were investigated. It was found the highest level of survival could be obtained with 32-cell eggs cooled at a rate of 0.3 degrees C min-1 or more slowly with seeding at -4 degrees C and warming at a rate of 5 degrees C min-1. Survival was influenced more by cooling rate than by warming rate. Using these optimum conditions, the survival of eggs was then investigated following cooling to various temperatures. While more than 50% of eggs were found to survive cooling to -30 degrees C, extremely low survival was noted from lower temperatures.
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12
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Matsumura T, Sawayama T, Nagata K, Mizuno F, Araki K, Iwamura N, Suzuki N. Avian schistosomiasis (paddy field dermatitis) in a rural city of Hyogo Prefecture, Japan. Kobe J Med Sci 1983; 29:161-9. [PMID: 6668897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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13
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Tomita M, Nakagawa T, Caragay R, Gasmen S, Iwamura N, Herrera F. The survey of parasitosis (I) in Bay (Philippines). Kobe J Med Sci 1982; 28:1-5. [PMID: 7087365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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14
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Nakata M, Tsuboi S, Takenaka M, Konishi Y, Kawashima R, Tomita M, Nakagawa T, Iwamura N, Fujita T. Specific cytosol binding proteins for 25(OH)D3 and 1.25(OH)2D3 in human breast cancers. Endocrinol Jpn 1981; 28:741-6. [PMID: 6286292 DOI: 10.1507/endocrj1954.28.741] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Binding proteins for 1.25 (OH) 2D3 were investigated in thirty breast cancers. Human breast cancer was shown to contain specific, high affinity cytosol binding proteins for 1.25 (OH) 2D3 and 25 (OH) D3. The binding protein for 1.25 (OH) 2D3 sedimented at 3.7 S and the binding protein for 25 (OH) D3 at about 6.0 S on sucrose density gradient analysis containing 0.3 M KCl and 1 mM dithiothreitol in buffer. Kd for 1.25 (OH) 2D3 were from 0.1 x 10(-11) M to 7.1 x 10(-11) M measured by Scatchard plots. Competition binding studies indicated that the relative specificity of the binding protein for 1.25 (OH) 2D3 much greater than 25 (OH) D3 greater than 1 alpha (OH) D3, 24,25 (OH)2D3 greater than D3 much greater than Estradiol-17 beta. 1.25 (OH) 2D3 receptor-positive was detected in twenty-eight out of thirty breast cancers.
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Tsuboi S, Caragay R, Gasmen S, Nakagawa T, Tomita M, Iwamura N, Herrera F. Tuberculosis survey (I) in Bay (Philippines). Kobe J Med Sci 1981; 27:159-63. [PMID: 7321486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Abstract
Neural afferent pathways mediating reflex hypotension and bradycardia during coronary occlusion (CO) were determined mainly on the right side in anesthetized cats. Brief occlusion of the left anterior descending (LAD) or circumflex coronary artery (Cx) reuslted in significant hypotension and bradycardia, both of which could be attenuated by bilateral (BVB), unilateral right (RVB), or left vagal cold blockade (LVB) in the nec. The degree of attenuation in the responses was greater as follows: BVB greater than RVB greater than LVB for LAD occlusion, and BVB greater than RBV = LBV for Cx occlusion. Randomized section of cardiac nerves, i.e., the pericoronary nerve, vagal cardiac nerve trunk, and caudal vagal cardiac nerves on the right side produced significant attenuations in the circulatory responses to CO. These results indicate that vagal afferent activity transmitted via these cardiac nerves plays an important role in mediating the reflex responses to CO. This conclusion was further substantiated by electrical stimulation of afferent fibers in thee nerves or by recording increased afferent spontaneous activity form them during CO.
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Abstract
Spread of excitation in isolated canine bundle branches was examined by microelectrode technique in order to investigate the possibility of dissociated impulse transmission in normal Purkinje fibers. In all experiments, local excitation of the preparation evoked either by fine bipolar extracellular electrodes or an intracellular microelectrode proceeded much faster along the longitudinal axis of the fibers than along the transverse axis. As a result, the spread of excitation in the vicinity of stimulating site showed significantly inhomogeneous character. The inhomogeneity of excitation spread became more manifest with more eccentric location of the stimulating site in a given preparation. Larger preparation showed greater degree of inhomogeneity. Nevertheless, the inhomogeneous spread of excitation alone appeared unlikely to provide multiply pathways which were functionally dissociated with each other. When premature stimulation was applied, however, different conductivity among fibers within a single false tendon was oberved, suggesting that each conducting element became more independent.
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Shimizu T, Iwamura N, Toyama J, Yamada K, Shibata S. Effect of cardiotonic polypeptide anthopleurin-A on canine Purkinje and ventricular muscle fibers. Eur J Pharmacol 1979; 56:7-13. [PMID: 467515 DOI: 10.1016/0014-2999(79)90426-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Effects of Anthopleurin-A (AP-A, polypeptide from sea anemone) were studied on electrophysiological properties of isolated canine Purkinje and ventricular muscle fibers. Ap-A (in concentrations above 20 micrograms/l) produced a dose-dependent increase in action potential duration (APD) and the refractory period (RFP) in electrically driven Purkinje fibers, but had no effect on other parameters. Similar but less prominent change in APD and RFP was observed in ventricular muscle fibers. AP-A in high concentrations (200 micrograms/l or higher) did alter the spontaneous firing rate of Purkinje fibers. Since AP-A in low concentrations will increase the refractory period of conducting fibers without affecting a conduction velocity, it may abolish some re-entrant arrhythmias.
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Hirata Y, Kodama I, Iwamura N, Shimizu T, Toyama J, Yamada K. Effects of verapamil on canine Purkinje fibres and ventricular muscle fibres with particular reference to the alternation of action potential duration after a sudden increase in driving rate. Cardiovasc Res 1979; 13:1-8. [PMID: 445526 DOI: 10.1093/cvr/13.1.1] [Citation(s) in RCA: 41] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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20
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Shimizu T, Iwamura N, Kodama I, Toyama J, Yamada K. Effects of beta-adrenergic blocking drug pindolol (LB46) on cardiac fibers in relation to its membrane effects. Jpn Heart J 1978; 19:865-76. [PMID: 750670 DOI: 10.1536/ihj.19.865] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Direct membrane effects and beta-adrenergic blocking action of pindolol were studied comparatively on isolated perfused cardiac fibers of dogs. In Purkinje fibers, the duration of transmembrane action potential decreased in concentrations higher than 0.5 mg/L. Maximum rate of depolarization also decreased in higher concentrations (5.0 mg/L or more). The functional refractory period decreased to a lesser degree compared with the decrease of the action potential duration. Nevertheless, slow-rising action potentials could not be abolished in premature responses, probably because of membrane depressant effects of this drug. In ventricular muscle fibers, these changes were minimum in the same range of concentrations. On the other hand, 0.05 mg/L of pindolol which was close to the therapeutic plasma concentrations and had no effect on action potentials of both Purkinje and ventricular muscle fibers, minimized the increase in automaticity of Purkinje fibers induced by 0.2 mg/L of isoproterenol. It is rationally speculated that the mechanism of antiarrhthmic action of pindolol is mainly due to its beta-adrenergic blocking action.
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21
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Iwamura N. Experimental study on the cause of ventricular aberrant conduction. Jpn Circ J 1978; 42:489-99. [PMID: 702771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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22
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Kodama I, Shimizu T, Iwamura N, Hirata Y, Toyama J, Yamada K. Effects of l-penbutolol (Hoe 893d) on the transmembrane potentials of canine purkinje fibers and ventricular muscle fibers. Arch Int Pharmacodyn Ther 1978; 231:232-42. [PMID: 25633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Intrinsic membrane effects (non-specific effects) and beta-adrenergic blocking action (specific effects) of l-penbutolol were studied using intracellular microelectrode techniques. l-Penbutolol in concentrations above 0.1 mg/L reduced the maximum rate of depolarization at phase O of both Purkinje fibers and ventricular muscle fibers without affecting their maximum diastolic potential. The action potential duration of Purkinje fibers were also shortened. The shortening of action potential duration and enhancement of automaticity in Purkinje fibers, normally induced by isoproterenol (0.2 mg/L), were antagonized by l-penbutolol in much lower concentraions (0.1--1.0 microgram/L) than those at which nonspecific effects are observed. The difference between these two concentration ranges is sufficient to suggest that l-penbutolol might be a highly specific beta-adrenergic blocking agent.
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Iwamura N, Kodama I, Shimizu T, Hirata Y, Toyama J, Yamada K. Functional properties of the left septal Purkinje network in premature activation of the ventricular conduction system. Am Heart J 1978; 95:60-9. [PMID: 619591 DOI: 10.1016/0002-8703(78)90397-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Toyama J, Sugenoya J, Iwamura N. [Bundle branch block and hemiblock]. Nihon Rinsho 1977; 35:2327-33. [PMID: 411962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Okuma K, Sugiyama O, Iwamura N, Wada M, Sugaya J. [Vectorcardiography - studies of fascicular block, with special reference to QRS changes to interruption of the left fascicular branch and the right bundle]. Nihon Rinsho 1975; 33:2663-5. [PMID: 1238657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Iwamura N. [Tuberculosis in Nepal; an example of tuberculosis control in a developing nation]. Kekkaku 1975; 50:21-2. [PMID: 1127848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Murae M, Iwamura N, Tada M, Takita S, Sumida M, Ida T, Katsuda M. A program of prevention and eradication of an endemic disease resembling Weil's disease in Sakaminato City, Tottori Prefecture in Japan. Yonago Acta Med 1966; 10:56-64. [PMID: 5934762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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