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41.
42.
Yoshiteru Harada Kunio Tanaka Kowa Yamashita Masataka Ishibashi Hiroshi Miyazaki Makoto Katori 《Prostaglandins & other lipid mediators》1983,26(1):79-90
Intrapleural injection of 2% λ-carrageenin caused the accumulation of exudate up to 19 hr. The rate of plasma exudation, measured by the exuded dye amounts for 20 min in the pleural cavity after intravenous injection of pontamine sky blue, showed a peak at 5 hr. Aspirin (100 mg/kg, i. p.) suppressed the dye exudation up to 5 hr, but did not at 7 hr. This inhibition coincided with the decrease of the PG and TXB2 levels, which were measured by gas chromatography-mass spectrometry, in the pleural exudate. In vitro experiments, MK-447, a phenolic compound, stimulates PG endoperoxide biosynthesis at lower doses and inhibits it at higher doses, acting as a tryptophan-like cofactor required by PG endoperoxide synthetase. This drug (0.3, 1.0 and 3.0 mg/kg, i. p.) suppressed the dye exudation dose-dependently up to 5 hr, but did not at 7 hr even at a higher dose, in combination with the dose-dependent decrease of the pleural level of PGE2, which was reported to be a major PG among PGs and TXB2 in the exudate in inducing the plasma exudation (Harada
; Prostaglandins,
: 881, 1982). Thus, the anti-inflammatory action of MK-447 can be explained by inhibition of PGE2 generation, giving no consideration to the role of oxygen-derived free radicals as a prime mediator in inflammation. 相似文献
43.
Crystallization and main-chain structure of neutral protease from Streptomyces caespitosus 总被引:1,自引:0,他引:1
A neutral protease, i.e., a zinc-containing metalloendoprotease from Streptomyces caespitosus, has been crystallized using acetone as a precipitating agent. The crystals diffract to better than 1.5 A resolution when a rotating anode X-ray generator is used as an X-ray source. Protein phase angles were calculated by the multiple isomorphous replacement method using two heavy-atom derivatives (HgCl2 and CH3HgCl). A 6 A resolution electron density map clearly showed molecular boundaries. Although its amino acid sequence is not known, the folding pattern of the polypeptide chain could be traced on a 2.5 A resolution electron density map. A large cleft, which is located on the molecular surface, was proved to be the active site of the enzyme by structure analyses of inhibitor-complex crystals. The highest electron density peak, which corresponds to the cleft, was assigned to a catalytically essential zinc atom on difference Fourier synthesis between native and EDTA-soaked crystals. 相似文献
44.
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46.
Motoshige Kawata Satoshi Harada Baltazar Antonio Kiyoharu Oono 《Plant Cell, Tissue and Organ Culture》1992,28(1):1-10
Protoplasts were isolated from callus derived from a single homozygous seed of Oryza sativa L. var. Norin 8. Thirty protoclones were randomly selected and these showed variation in regeneration frequency ranging from 0–87% with an average of 52%. The potential for regeneration of each protoclone as reflected in the regeneration frequency was analyzed five times over a period of 250 days and showed that the protoclones can be classified into three types, namely: protoclones with high regeneration frequency; protoclones with low regeneration frequency, both of which maintained their respective levels of regeneration potential; and protoclones with gradually decreasing regeneration frequency. Secondary protoclones established from protoplasts isolated from some of these protoclones and regenerated 2–3 times for a period of 120 days also showed further reduction in regeneration frequency. The polypeptide composition analyzed by two dimensional gel electrophoresis suggests the presence of specific polypeptides related to regeneration potential. Analysis of ploidy level based on plant morphology and pollen size suggests the predominance of tetraploids among the regenerated plants. 相似文献
47.
K Fujimoto I Kubota Y Yasuda-Kamatani H Minakata K Nomoto M Yoshida A Harada Y Muneoka M Kobayashi 《Biochemical and biophysical research communications》1991,177(2):847-853
Achatin-I previously purified from the ganglia of the African giant snail Achatina fulica was isolated from the atria of this snail. Achatin-I appeared to enhance the cardiac activity in two ways; centrally this peptide increased impulse frequency and produced spike broadening of the identified heart excitatory neuron, PON, and peripherally it enhanced amplitude and frequency of the heart beat. Achatin-I showed excitatory actions not only on the heart but on several other muscles. 相似文献
48.
H Shimano C Fukazawa Y Shibasaki N Mori T Gotoda K Harada M Shimada N Yamada Y Yazaki F Takaku 《Biochimica et biophysica acta》1991,1086(3):245-254
To investigate the role of apolipoprotein E (apo E) secreted by peripheral tissues in local lipoprotein metabolism, we developed a cell strain that constitutively produced and secreted apo E. A fusion plasmid containing rat apo E genomic DNA under control of mouse metallothionein promotor was constructed and transfected into Chinese hamster ovary cells. A stable transformant designated CHO-MAEII constitutively secreted rat apo E mainly in the form of sialylated free protein. The secretion was further enhanced by metal induction up to 1 micrograms apo E/ml per 12 h. When incubated with 125I-labeled very low density lipoprotein (125I-VLDL) at 37 degrees C, CHO-MAEII took up and degraded 125I-VLDL with higher affinity than control cells. Furthermore, considerable amount of methylated 125I-VLDL was degraded by CHO-MAEII, while no methylated 125I-VLDL was degraded by control cells. No significant differences were found in the uptake of 125I-LDL. The data indicated that apo E molecules secreted by CHO-MAEII were transferred to 125-VLDL particles, which caused a higher affinity of these particles for LDL receptors on the cells. It is suggested that apo E secreted from peripheral tissues enhances the uptake of lipoproteins by themselves or by surrounding cells in the local environment which demand cholesterol and express LDL receptors. CHO-MAEII was a good model for these 'auto- or paracrine-like functions' of apo E. 相似文献
49.
The role of cAMP in regulation of intracellular pH in the confluent LLC-PK1 cells was investigated. DibutyrylcAMP and forskolin induce intracellular acidification. This acidification is inhibited by DIDS and ethacrynic acid, inhibitors of Na(+)-independent Cl-/HCO3- exchange, and by removal of extracellular Cl-. In addition, Bt2 cAMP causes Cl- entry into LLC-PK1 cells. These results suggest that cAMP activates Cl- transport, namely Na(+)-independent Cl-/HCO3- exchange, which participates in pHi regulation. 相似文献
50.