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Chiba S, Tsukada M. Potent antagonistic action of OPC-31260, a vasopressin V2 receptor antagonist, on [Arg8]vasopressin-induced vasoconstriction in isolated simian femoral arteries. Eur J Pharmacol 1992; 221:393-5. [PMID: 1330628 DOI: 10.1016/0014-2999(92)90730-r] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Using a perfusion technique with isolated vessels, we investigated the effect of OPC-21268 (a selective V1 receptor antagonist) and OPC-31260 (a V2 receptor antagonist) on arginine vasopressin (AVP)- or norepinephrine (NE)-induced vasoconstrictions of isolated simian femoral arteries. The dose-response curve for AVP was shifted to the right in parallel by OPC-31260 but not by OPC-21268. Neither antagonist significantly modified the NE-induced vasoconstriction. On the basis of these results, there are functionally constrictory vasopressin V2 receptors but no V1 receptors in isolated simian femoral arteries.
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102
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Kageshima H, Tsukada M. Theory of scanning tunneling microscopy and spectroscopy on Si(100) reconstructed surfaces. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 46:6928-6937. [PMID: 10002397 DOI: 10.1103/physrevb.46.6928] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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103
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Gotoh Y, Tsukada M, Minoura N. Chemical modification of arginyl residues in silk fibroin: 1. Reaction of 1,2-cyclohexanedione in borate buffer. Int J Biol Macromol 1992; 14:198-200. [PMID: 1504039 DOI: 10.1016/s0141-8130(05)80027-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Chemical modifications of silk fibroin were attempted in order to add new properties and functions to silk fibroin. The arginyl residue in solubilized silk fibroin was chemically modified with the reaction of 1,2-cyclohexanedione in borate buffer. FT-i.r. and c.d. spectra of the silk fibroin before and after the modification indicated that the fraction of random coil conformation increased with the modification. The chemical stability of the modified silk fibroin membrane was investigated in vitro with phosphate buffer. The modified arginyl residue in the membrane was considerably regenerated with the treatment in phosphate buffer.
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104
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Tsukada M, Goto Y, Freddi G, Shiozaki H. Chemical modification of silk with aromatic acid anhydrides. J Appl Polym Sci 1992. [DOI: 10.1002/app.1992.070450707] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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105
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Koizumi A, Tsukada M, Kamiyama S. A skin-specific MMTV provirus is stably transmitted by horizontal transmission. TOHOKU J EXP MED 1992; 167:171-80. [PMID: 1336902 DOI: 10.1620/tjem.167.171] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Mouse mammary tumor virus (MMTV) is a retrovirus with a life cycle that remains to be elucidated. In establishing Mtv-4 congenic mice, an extra copy of the MMTV provirus was found specifically in the skin of both sexes of SHN mice but not in C3H/He mice. This extra copy was not, however, found in other normal tissues such as brain, lung, liver, spleen, kidney, uterus, testis, and mammary glands from SHN or C3H/He mice. In the skin of SHN mice, an 11-kb DNA fragment, which approximates in size to the entire MMTV genome, was detected in undigested high-molecular weight DNA. This unique MMTV provirus was shown to be transmitted horizontally from SHN mice to exogenous-MMTV-free C3H/He mice through nursing. The virus is thus concluded to be exogenous. Clusters of MMTV type A particles were found in sebaceous glands by electronmicroscopic examination. The present findings indicates that exogenous MMTV may be stably maintained in the skin as an unintegrated provirus during its life cycle.
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106
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Watanabe S, Aono M, Tsukada M. First-principles calculation of STM images of the Si(111)-Ag surface. Ultramicroscopy 1992. [DOI: 10.1016/0304-3991(92)90252-f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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107
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Koizumi A, Tsukada M, Wada Y, Masuda H, Weindruch R. Mitotic activity in mice is suppressed by energy restriction-induced torpor. J Nutr 1992; 122:1446-53. [PMID: 1619471 DOI: 10.1093/jn/122.7.1446] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
We monitored core body temperature by telemetry in energy-restricted (201 kJ/wk) and control (397 kJ/wk) C57BL/6 and SHN/C3H F1 mice to determine whether torpor may be involved in the suppression of mitotic activities resulting from energy restriction. The energy restriction regimen employed inhibited the development of cancer and greatly extended longevity in both these mouse strains. Male and female C57BL/6 mice subjected to energy restriction from 4 wk of age and tested at 3 mo of age became torporific (body temperature less than 31 degrees C) at ambient air temperatures of 20-22 degrees C, whereas control animals stayed euthermic (greater than 35 degrees C). Energy restriction also induced torpor in 3- and 13-mo-old SHN/C3H F1 female mice, whereas 3-, 13- and 24-mo-old control mice were euthermic. Energy restriction decreased mitotic activities to approximately 30% of control values in both jejunum and epidermis in 3-mo-old female C57BL/6 mice maintained at 20-22 degrees C. However, this suppression of mitotic activities was antagonized by housing the energy-restricted mice at 30 degrees C for 2 wk, indicating that torpor plays a substantial role in suppressing mitotic activities in energy-restricted mice.
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108
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Koizumi A, Tsukada M, Masuda H, Kamiyama S, Walford RL. Specific inhibition of pituitary prolactin production by energy restriction in C3H/SHN female mice. Mech Ageing Dev 1992; 64:21-35. [PMID: 1378522 DOI: 10.1016/0047-6374(92)90093-s] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Pituitaries were excised from control (C; 95 kcal/week) or energy restricted (ER; 48 kcal/week) female mice of 2, 3, 7, and 18 months of age. The total RNA and relative actin mRNA amounts in the pituitary were significantly greater in C than in ER mice both at 7 and 18 months. Prolactin (PRL) mRNA, standardized with actin mRNA, was significantly less in ER mice of 7 (50%) and 18 (51%) months of age than in age-matched controls, suggestive of specific inhibition of PRL mRNA transcription. Pituitary RNA and actin mRNA increased from 7 to 18 months in C mice but not in ER mice. Similarly, mean pituitary volumes increased between 2 and 18 months in C mice but not in ER mice. PRL mRNA, standardized with actin mRNA, did not change in either C or ER mice 7-18 months of age. All examined C mice of 3, 7, and 18 months of age had estrous cycles but none of the ER mice of the same ages. After 1 month of ER, the pituitary volumes and serum insulin concentrations in 2-month-old female mice were reduced. Thus net reduction of PRL mRNA per pituitary by ER is attributable to decreases in pituitary size and specific inhibition of PRL production, both of which may be due to low estrogen and insulin levels.
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109
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Furusaki A, Takayanagi H, Tsukada M. Josephson effect of the superconducting quantum point contact. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 45:10563-10575. [PMID: 10000963 DOI: 10.1103/physrevb.45.10563] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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110
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Chiba S, Tsukada M. Blocking effects of OPC-21268 and OPC-31260 (vasopressin V1- and V2-receptor antagonists) on vasopressin-induced constrictions in isolated, perfused dog femoral arteries. JAPANESE JOURNAL OF PHARMACOLOGY 1992; 59:133-5. [PMID: 1324373 DOI: 10.1254/jjp.59.133] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Using a perfusion technique of isolated vessels, constrictor responses to vasopressin (VP) and norepinephrine (NE) were investigated in perfused dog femoral arteries. Both OPC-21268, a selective V1-antagonist, and OPC-31260, a selective V2-antagonist, significantly shifted the VP-induced dose response curves to the right without influencing the NE-induced ones. The blocking effects of OPC-31260 were much greater than those of OPC-21268, suggesting that there may probably be functional V1- and V2-receptors in isolated dog femoral arteries that mediate vasoconstriction.
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111
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Chiba S, Tsukada M. Histamine-induced vasodilations mediated by H1- and H2-receptors in isolated rat common carotid arteries. Heart Vessels 1991; 6:185-90. [PMID: 1839304 DOI: 10.1007/bf02125095] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Using the cannula inserting method, the vasodilatory effects of histamine were analysed employing selective histamine H1- and H2-receptor agonists and antagonists in isolated, perfused rat common carotid arterial preparations which were preconstricted by a continuous infusion of phenylephrine with propranolol. Histamine, 2-pyridylethylamine (2-PEA) (a selective H1-agonist) and dimaprit (a selective H2-agonist) produced a vasodilation in a dose-related manner. The order of potency was histamine greater than dimaprit greater than 2-PEA. Histamine-induced dilations were significantly inhibited by either diphenhydramine (a selective H1-antagonist) or cimetidine (a selective H2-antagonist). 2-PEA-induced dilations were significantly inhibited by diphenhydramine but not by cimetidine. Dimaprit-induced dilations were significantly blocked by cimetidine but not by diphenhydramine. ACh-, histamine-, 2-PEA- and dimaprit-induced dilations were significantly suppressed by removal of the endothelium. From these results, it is concluded that (1) isolated rat common carotid arteries have both H1- and H2-receptors, (2) there are few vasoconstrictory H1-receptors, (3) both H1- and H2-receptors mediate only vasodilation but not vasoconstriction, and (4) EDRF from the endothelium might participate in histamine-induced vasodilation via not only H1- but also H2-receptors.
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112
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Chiba S, Tsukada M. Potent vasoconstriction by tyramine but no significant constriction by nicotine in isolated dog ear arteries. TOHOKU J EXP MED 1991; 165:239-41. [PMID: 1807012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Using the cannula inserted method, vascular effects of nicotine were investigated in isolated, perfused dog intermediate auricular arteries, comparing with those of norepinephrine and tyramine. Norepinephrine and tyramine produced strong vasoconstrictions in a dose-related manner, but nicotine did not induce any significant vasoconstriction.
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113
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Tsukada M, Wada Y, Hamade N, Masuda H, Koizumi A. Stable Lyonization of X-linked pgk-1 gene during aging in normal tissues and tumors of mice carrying Searle's translocation. JOURNAL OF GERONTOLOGY 1991; 46:B213-6. [PMID: 1940071 DOI: 10.1093/geronj/46.6.b213] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We investigated whether age-dependent reactivation of a repressed X-linked gene occurs. Subjects were female mice, carrying the X-autosomal translocation, T(X;16)16H (Searle's translocation). The mice were also heterozygous, for the X-linked gene coding for phosphoglycerate kinase (T16H pgk-1b/+ pgk-1a and pgk-1a was selectively repressed in these mice (McMahon and Monk, 1983). An electrophoretic method was applied to determine the PGK-1 allozyme patterns in blood, bone marrow, brain, gastrointestinal tract, liver, heart, spleen, and uterus (including tumor tissues when found). Samples were collected from mice of three different ages: 2 months (n = 4), 11 to 12 months (n = 10), or 18 to 21 months (n = 15). The lowest detection limit of the relative cellular population expressing the PGK-1A allozyme was found to be 2%, which was sensitive enough to detect the reported reactivation ratio (more than 10% of cells in a lower power microscopic field). We could not detect PGK-1A activity in any organ, including tumors in any age group, leading to the conclusion that reactivation of the repressed pgk-1a gene did not occur during aging.
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114
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Watanabe S, Aono M, Tsukada M. Theoretical calculations of the scanning-tunneling-microscopy images of the Si(111) sqrt 3 x sqrt 3 -Ag surface. PHYSICAL REVIEW. B, CONDENSED MATTER 1991; 44:8330-8333. [PMID: 9998774 DOI: 10.1103/physrevb.44.8330] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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115
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Tanaka Y, Tsukada M. Phase-dependent energy spectrum of quasiparticles in a superconducting superlattice. PHYSICAL REVIEW. B, CONDENSED MATTER 1991; 44:7578-7584. [PMID: 9998673 DOI: 10.1103/physrevb.44.7578] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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116
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Chiba S, Tsukada M. Potentiation of acetaldehyde-induced vasoconstrictions by cocaine in isolated and perfused arteries. TOHOKU J EXP MED 1991; 165:63-5. [PMID: 1798978 DOI: 10.1620/tjem.165.63] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Vasoconstrictor responses to acetaldehyde (AA), norepinephrine (NE) and tyramine were investigated in isolated, perfused canine intermediate auricular (ear) arteries. Single injections of small doses of AA (1-3 mumol) induced a vasoconstriction in a dose-related manner and showed no tachyphylaxis. Cocaine significantly inhibited tyramine-induced vasoconstrictions, but NE- and AA-induced vasoconstrictions were rather significantly enhanced.
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117
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Chiba S, Tsukada M. Evidence for the existence of postsynaptic beta-1 and beta-2 adrenoceptors in isolated simian facial veins. Heart Vessels 1991; 6:168-74. [PMID: 1680847 DOI: 10.1007/bf02058282] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
With the use of a steel cannula inserting method, the actions of the beta-adrenoceptor agonists, noradrenaline (NA, a mixed agonist), isoprenaline (a mixed agonist), dobutamine (a selective beta-1 agonist), salbutamol, and procaterol (selective beta-2 agonists), were investigated on isolated and perfused simian facial veins. Each beta-agonist usually induced a vasodilation in a dose-related manner in non-preconstricted vessel preparations. The rank order of potency was isoprenaline much greater than NA greater than dobutamine greater than salbutamol greater than procaterol. NA- and isoprenaline-induced vasodilations were inhibited by either metoprolol (a selective beta-1 adrenoceptor antagonist) or ICI 118,551 (a selective beta-2 antagonist). After beta-1 blockade, NA produced a vasoconstriction which was readily blocked by bunazosin (an alpha-1 antagonist). Dobutamine-induced vasodilations were strongly suppressed by metoprolol and slightly blocked by ICI 118,551. Salbutamol-induced vasodilations were blocked by metoprolol, while ICI 118,551 more markedly inhibited these dilations. From these results, it was concluded that there are abundant beta-adrenoceptors and predominantly beta-1 adrenoceptors in isolated simian facial veins.
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118
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Shinoda T, Shima N, Tsukada M. Electronic structure of DNA by DV-X alpha cluster calculations. I. d(GG).d(CC), d(CG)2, d(GC)2 A and B conformations. J Theor Biol 1991; 151:433-66. [PMID: 1943152 DOI: 10.1016/s0022-5193(05)80365-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The electronic structure of d(GG).d(CC), d(CG)2, d(GC)2 which are stacked base pairs in the DNA double helix, are elucidated for both A and B conformations in detail by DV-X alpha cluster calculations. These three DNA double helix fragments are constructed from the same bases, G and C, but the electronic structure of the fragments for A and B conformations differs from each other characteristically. In particular, the electronic states of the O2 and O3 in phosphates differ drastically from each other, and might play a crucial role as recognition sites in various reaction processes concerning DNA. These differences are caused by the delicate differences in the admixture of the orbital components and the intra- and inter-bases interactions. Contour maps of the wavefunction of the HOMO and LUMO are compared among the stacking isomers.
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119
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Furusaki A, Takayanagi H, Tsukada M. Theory of quantum conduction of supercurrent through a constriction. PHYSICAL REVIEW LETTERS 1991; 67:132-135. [PMID: 10044070 DOI: 10.1103/physrevlett.67.132] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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120
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Furusaki A, Tsukada M. Current-carrying states in Josephson junctions. PHYSICAL REVIEW. B, CONDENSED MATTER 1991; 43:10164-10169. [PMID: 9996733 DOI: 10.1103/physrevb.43.10164] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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121
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Tsukada M, Sasaki-Yagi Y, Kimura S, Imanishi Y. Cell interactions of enkephalin/polypeptide conjugates. J Mol Recognit 1991; 4:35-41. [PMID: 1657067 DOI: 10.1002/jmr.300040106] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Enkephalin molecules were bound to poly(Lys) (poly-K) or poly(Ala-Lys-Ala-Leu) (poly-A) and their interactions with NG108-15 cells, platelets, erythrocytes and fibroblast cells were investigated. A fluorescent probe, rhodamine, also was bound to the conjugates for monitoring interactions with these cells. Observations by fluorescence microscopy revealed that NG108-15 cells, platelets, and fibroblast cells were labelled by the conjugates, whereas erythrocytes were not. Since polypeptides without enkephalin moieties were only weakly adsorbed on the cells, it was concluded that the enkephalin/polypeptide conjugates were bound specifically to receptors on the cell membrane. Interestingly, when the enkephalin/poly-K conjugate was bound to NG108-15 and fibroblast cells, fluorescent patches appeared on the membrane. Such patch formation was not clearly observed with an enkephalin/rhodamine or enkephalin/poly-A conjugate. In the case of fibroblast cells, the fluorescence converged to a large cluster, which was ultimately internalized. The results suggest that clustering of the receptors in cell membranes is influenced by the carrier polymer presumably due to cross-linking of the receptors and/or the effect of the cationic polypeptides.
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122
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Chiba S, Tsukada M. Muscarinic receptor subtype in isolated dog and monkey facial vein. JAPANESE JOURNAL OF PHARMACOLOGY 1991; 55:291-3. [PMID: 1712405 DOI: 10.1254/jjp.55.291] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Using the cannula inserting method, we investigated vascular responses to ACh and McN-A-343 (a M1-agonist) in isolated and perfused canine and simian facial veins in non-preconstricted conditions. ACh usually induced only a vasoconstriction, but McN-A-343 did not induce any significant vasoconstriction. It is concluded that canine and simian facial veins contain very few receptors of the muscarinic M1-subtype; and according to previous studies, these vessels have abundant M3-receptors.
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123
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Chiba S, Tsukada M. Predominant acetylcholine-induced vasoconstriction in isolated, perfused simian facial veins. Eur J Pharmacol 1990; 191:311-8. [PMID: 1982268 DOI: 10.1016/0014-2999(90)94163-r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Using the cannula insertion method, we investigated the vascular response to acetylcholine (ACh) and other vasoactive substances. ACh consistently induced only vasoconstriction, whereas isoproterenol and norepinephrine usually induced dilatation. Vasoconstriction induced by phenylephrine was less potent than that induced by ACh. Clonidine and xylazine did not induce significant vascular responses. ACh-induced constrictions were readily inhibited by atropine and slightly potentiated by physostigmine. They were slightly but significantly inhibited by pirenzepine (a muscarinic M1-receptor antagonist), but not influenced by AF-DX 116 (a M2-receptor antagonist). 4-DAMP (4-diphenylacetoxy N-methylpiperidine; a M3-receptor antagonist), strongly inhibited the ACh-induced constrictions. They were not modified by bunazosin but slightly suppressed by diltiazem. Removal of the endothelium did not significantly modify the ACh-induced constrictions. From our results, we conclude that the simian facial vein has many constrictory muscarinic receptors, especially of the M3 subtype.
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124
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Koizumi A, Wada Y, Tsukada M, Kamiyama S, Weindruch R. Effects of energy restriction on mouse mammary tumor virus mRNA levels in mammary glands and uterus and on uterine endometrial hyperplasia and pituitary histology in C3H/SHN F1 mice. J Nutr 1990; 120:1401-11. [PMID: 2172493 DOI: 10.1093/jn/120.11.1401] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
We investigated the effects of energy restriction on the pituitary-ovarian axis and on a hormone responsive gene, the mouse mammary tumor virus (MMTV). Female C3H/SHN F1-hybrid mice, known to display a high incidence of mammary tumors, ate an energy-restricted diet (48 kcal/wk) or a control diet (95 kcal/wk) beginning at the time of weaning. By 67 wk of age, 12 of 32 mice in the control group, but none of the 33 mice in the energy-restricted group, had developed mammary tumors. Six tumor-free mice from each group were studied in detail at 67 wk of age. All six tumor-free control mice, but none of the six energy-restricted mice, showed uterine endometrial hyperplasia at autopsy. Mice subjected to energy restriction did not display an estrous cycle. The average levels of MMTV mRNA in mammary glands and uteri were strongly reduced by energy restriction. MMTV mRNA levels in mammary glands from control mice were two orders of magnitude lower than those in mammary tumors. Energy restriction lowered the percentage of pituitary mammatropes and suppressed proliferation of mammatropes with advancing age. Energy restriction thus appeared to inhibit endometrial hyperplasia and to decrease MMTV production at the mRNA level in the mammary glands and in the uterus. These effects may be a consequence of hormonal changes originating at the pituitary-ovarian axis.
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125
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