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71.
Membrane Viscosity Correlates with α1 -Adrenergic Signal Transduction of the Aged Rat Cerebral Cortex
Atsushi Miyamoto Tsunehisa Araiso Tomiyasu Koyama Hideyo Ohshika 《Journal of neurochemistry》1990,55(1):70-75
We investigated, using adult (2-month-old) and senescent (12- and 24-month-old) rats, the effects of aging on the relationship between the alpha 1-adrenergic coupling system and the membrane viscosity of the cerebral cortex. There was no age-related difference in the KD values of [3H]prazosin binding on the membranes. The Bmax values of [3H]prazosin binding were reduced with advanced age. Norepinephrine-induced formation of 3H-labeled inositol phosphates (3H-IPs) in the slices increased with advanced age. The EC50 values for norepinephrine to stimulate the formation of 3H-IPs at advanced age were lower than that at adult age. The cholesterol content in membranes increased with advanced age. No changes in the phospholipid content in membranes were observed with advanced age. Concomitantly, an increase of the molar ratio of cholesterol to phospholipids was observed with advanced age. The membrane viscosity as measured by 1,6-diphenyl-1,3,5-hexatriene increased with advanced age. These results indicate that the altered cholesterol content and/or viscosity in cortical membranes of the aged rat may account for the loss of alpha 1-adrenergic receptor density and/or compensatory changes in the receptor-phospholipase C coupling system. 相似文献
72.
Isolation of Glutamyltaurine from Bovine Brains and Proof of Its γ-Linkage by the B/E Linked Scan SIMS Technique 总被引:1,自引:1,他引:0
Ko Nakamura Kunihiko Higashiura Naoharu Nishimura Atsushi Yamamoto Ikuo Tooyama Hiroshi Kimura Kazuharu Ienaga 《Journal of neurochemistry》1990,55(3):1064-1066
We isolated a glutamyltaurine from bovine brains and determined its structure as gamma-glutamyltaurine (gamma-Glu-Tau; glutaurine) by use of a new mass spectrometric technique [B/E linked scan sputtered ion mass spectrometry (SIMS)], which we have recently shown to be useful for distinguishing the gamma- from the alpha-isomer of glutamyl-dipeptides. Neither the alpha-isomer of glutamyltaurine nor any aspartyltaurines could be detected in bovine brain. 相似文献
73.
74.
Ichiro Shimada Yuji Maki Hiroshi Sugiyama 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1989,165(2):193-196
Summary
N-Acylation changed nonstimulatory Dvaline into a clear stimulant of the sugar receptor of the fleshfly,Boettcherisca peregrina. Of theN-acyl-D-valines, the most stimulatory wasN-acetyl-D-valine. Similar changes into stimulants were also observed in other aliphatic amino acids such as leucine and methionine. Dose-response curves ofN-acetyl-D-valine suggested an increase of binding affinity, compared with that ofN-acetyl-L-valine. By treatment experiment with pronase 10 mg/ml, stimulatoryN-acetyl-D-amino acids were suggested to react with the specific alkyl site (R site), which was presumed to discriminate between L- and D-forms of the amino acids through steric hindrance between its own spatial barrier and D-amino acids (Shimada and Isono 1978; Shimada and Tanimura 1981).This change of chiral recognition cannot be explained by simple steric hindrance at the R site. It means, instead, that a hydrophobic subsite rather than a spatial barrier must be postulated. 相似文献
75.
76.
Cytochrome P-450 and chromosome damage by cyclophosphamide in LEC strain rats predisposed to hereditary hepatitis and liver cancer 总被引:3,自引:0,他引:3
LEC strain rats predisposed to hereditary hepatitis and liver cancer were examined for hepatic drug-metabolizing ability and the inducibility of chromosome damage by cyclophosphamide (CP) in somatic cells. Whereas the hepatic cytochrome P-450 contents and the activities of cytochrome P-450-catalyzed monooxygenases were lower in females than in males of both LEC and control LEA strains, male LEC rats exhibited significantly reduced cytochrome P-450 contents and monooxygenase activities compared with male LEA rats. When exposed to CP, a promutagen/procarcinogen requiring P-450-dependent metabolic activation, the frequencies of chromosome aberrations and sister-chromatid exchanges (SCEs) in bone marrow cells tended to be lower in females than in males of each strain and lower in LEC than in LEA rats of the same sex. In particular, the CP-induced SCEs were substantially lower in LEC rats. However, no such sex and strain differences were found in the SCE frequencies in regenerating hepatocytes of partially hepatectomized rats exposed to CP. 相似文献
77.
Naoto Ohnishi Hiroaki Kodania Satoshi Ando Atsushi Komamine 《Physiologia plantarum》1990,80(1):95-101
The effects of inhibition of the synthesis of protein, mRNA or rRNA on the progression of the cell cycle have been analyzed in cultures of Catharanthus roseus in which cells were induced to divide in synchrony by the double phosphate starvation method. The partial inhibition of protein synthesis at the G1 phase by anisoniycio or cycloheximide caused the arrest of cells in the G1 phase or delayed the entry of cells into the S phase. When protein synthesis was partially inhibited at the S phase, cell division occurred to about the same extent as in the control. When asynchronously dividing cells were treated with cycloheximide, cells accumulated in the G1 phase, as shown by flow-cytometric analysis. The partial inhibition of mRNA synthesis by α-amanitin at the G1 phase caused the arrest of cells in the G1 phase, although partial inhibition of mRNA synthesis at the S phase had little effect on cell division. In the case of inhibition of synthesis of rRNA by actinomycin D at the G1 phase, initiation of DNA synthesis was observed, but no subsequent DNA synthesis or the division of cells occurred. However, the addition of actinomycin D during the S phase had no effect on cell division. These results suggest that specific protein(s), required for the progression of the cell cycle, are synthesized in the G1 phase, and that the mRNA(s) that encode these proteins are also synthesized at the G1 phase. 相似文献
78.
79.
T Chiba A Kishi M Sugiyama H Amanuma M Machide Y Nagata K Todokoro 《Biochemical and biophysical research communications》1992,186(3):1236-1241
The cytoplasmic domains of the erythropoietin receptor essential for signal transduction were identified by assessing a series of truncated and deletional mutant receptors. A 91-amino acid region proximal to the transmembrane domain was required for growth signaling. In this region, residues between 353Pro and 362His and between 278Gln and 308Leu appeared to constitute the essential cytoplasmic domains. These two domains contain the conserved amino acids common in the cytokine receptor superfamily, which indicates that these domains in the cytoplasmic regions of the erythropoietin receptor may be important for interaction with common signal transducers or protein tyrosine kinases. 相似文献
80.
M Hayakawa K Kosaka S Sugiyama K Yokoo H Aoyama Y Izawa T Ozawa 《Biochemistry international》1990,21(3):573-579
It is postulated that toxic substances (burn toxin) synthesized in burned skin are transferred into general circulation and cause multiple organ failure. We found a highly cytotoxic substance, leukotoxin, a linoleate epoxide, exists in burned skin. Leukotoxin, as the name indicates, was synthesized by leukocytes from linoleate as a substrate. The aim of this study is to evaluate the possibility of leukotoxin as a burn toxin. We studied plasma leukotoxin level of four patients with extensive burns (over 50% of body surface area) and examined coagulation studies in these patients. We detected considerable amounts of leukotoxin (11.4 nmol/ml-37.0 nmol/ml) in all patients. Leukotoxin was not detected in the control subjects. Pulmonary edema, cardiac failure, and coagulation abnormalities were found in these patients. Exogeneously administered leukotoxin induced similar pathological conditions in experimental animals to those observed in patients with extensive burns. Hence, it is concluded that leukotoxin is a responsible substance as a burn toxin. 相似文献