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61.
62.
Takahiro Kobayashi Ikuo Morita Sei-Itsu Murota 《Prostaglandins & other lipid mediators》1983,26(2):303-310
Effects of nitrogen dioxide (NO2) exposure on prostacyclin (PGIP2) synthesis in the rat lung and thromboxane A2 (TXA2) synthesis in the platelets were studied. Male Wistar rats were exposed to 10 ppm NO2 for 1, 3, 5, 7 and 14 days. PGI2 synthesizing activity of homogenized lung decreased. The damage of PGI2 synthesizing activity reaches its maximum at 3 days. At 14 days, PGI2 synthesizing activity returned to the normal level. The activity of PGI2 synthetase decreased significantly. The formation of lipid peroxides due to NO2 exposure may cause the depression of PGI2 synthesizing activity of lung. On the other hand, platelet TXA2 synthesizing activity increased. This increased TXA2 synthesizing activity lasted at least till 3 days. Then, it returned to the normal level. The counts of platelet were decreased significantly by 1, 3, 5 and 7 days NO2 exposure. Then the decreased counts of platelet returned to the normal level at 14 days NO2 exposure. These results indicate that the depression of PGI2 synthesizing activity lung by NO2 exposure cause an increase in TXA2 synthesizing activity of platelets. It may contribute to induce platelet aggregation and to the observed decrease in the number of platelets during NO2 exposure. 相似文献
63.
Summary A serum-free culture system supplemented with neural tissue extract for normal and tumor human esophagi was applied to the
culture of mouse esophageal epithelium. Similar to mouse mesenchyme and skin epithelium, esophageal epithelial lines (MEE)
emerged after serial culture. The cells had an apparent unlimited life span but retained morphology and other characteristics
of normal epithelial cells. The cells formed a small cyst consisting of keratined squamous epithelium in syngenic hosts. A
screen for growth factors that stimulated growth of the nonmalignant MEE cells in the absence of neural extract revealed that
epidermal growth factor (EGF) and heparin-binding (fibroblast) growth factors (HBGF) were most effective. An HBGF-like activity
was apparent in extracts of rapidly proliferating but not quiescent MEE cells at low or confluent densities. A cloned cell
line (MEE/C8) was selected from MEE cell cultures in the absence of neural extract. MEE/C8 cells proliferated independent
of either EGF or HBGF at rates equal to MEE cells, cell extracts exhibited HBGF-like activity at all stages of proliferation,
and the cells formed large invasive tumors in syngenic hosts. The HBGF-like activity present in extracts of tumorigenic MEE/C8
and proliferating nonmalignant MEE cells had properties similar to HBGF-1 (acidic fibroblast growth factor). These results
constitute a cultured mouse esophageal epithelial cell model for study of conversion of immortalized premalignant cells to
malignant cells, and suggest that conversion from a state of cell cycle-dependent autocrine expression of one or more members
of the HBGF family to a state of constitutive expression correlates with and may contribute to malignancy.
The work was supported in part by grants CA37589 and DK35310 to Dr. McKeehan, from the National Cancer Institute, Bethesda,
MD. 相似文献
64.
Molecular cloning of the protocatechuate 4,5-dioxygenase genes of Pseudomonas paucimobilis. 总被引:9,自引:8,他引:1 下载免费PDF全文
Y Noda S Nishikawa K Shiozuka H Kadokura H Nakajima K Yoda Y Katayama N Morohoshi T Haraguchi M Yamasaki 《Journal of bacteriology》1990,172(5):2704-2709
We determined the nucleotide sequence of a 1.9-kilobase fragment of Pseudomonas paucimobilis SYK6 chromosomal DNA that included genes encoding protocatechuate 4,5-dioxygenase, the enzyme responsible for the aromatic ring fission of protocatechuate. Two open reading frames of 417 and 906 base pairs were found that had no homology with previously reported sequences, including those encoding protocatechuate 3,4-dioxygenase. Since both open reading frames were indispensable for the enzyme activity, they should encode the subunits of protocatechuate 4,5-dioxygenase. We named these genes ligA and ligB. Protocatechuate 4,5-dioxygenase was efficiently expressed in Escherichia coli with the aid of the lac promoter, and the polypeptides of the ligA and ligB gene products were identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and amino acid sequencing. 相似文献
65.
N Katayama Y Yamagata H Hashimoto H Kanazawa T Tsuchiya M Tsuda 《Biochemical and biophysical research communications》1990,167(3):1348-1354
Addition of concanavalin A (Con A) to mouse neuroblastoma N18TG2 cells cultured with dibutyryl-cAMP which can stimulate neurite outgrowth, stopped the neuritic processes effectively. The extended neurites showed a gradual retraction for at least 8 hrs after addition of Con A, while addition of colchicine caused rapid retraction of the neurites. Immunocytochemistry showed that the addition of Con A did not disorganize the microtubules but the addition of colchicine did. The increase in beta-tubulin mRNA expression which was observed after cell culture and after stimulation by dB-cAMP was suppressed by the addition of Con A. Con A did not affect the beta-tubulin mRNA expression when the cells had already been cultured, while colchicine drastically decreased it. Thus, Con A appeared to affect the beta-tubulin mRNA expression in a different manner from colchicine, probably through inhibition of cell movement. 相似文献
66.
Akitane Mori Masayuki Akagi Yasuto Katayama Yoko Watanabe 《Journal of neurochemistry》1980,35(3):603-605
: Guanidino compounds in the cobalt-induced epileptogenic cerebral cortex of cats were fluorometrically analysed by a JASCO G-520 guanidino compounds analyser, and an unknown high peak was observed in the chromatogram that was identical to the peak of authentic α-guanidinoglutaric acid. In another experiment, the substance was extracted from the cobalt focus tissue, converted into dimethylpyrimidyl derivative-butylester, and analysed by a GC/MS technique. The mass spectrum of the substance was identical to the dimethylpyrimidyl derivative of α-guanidinoglutaric acid butylester (M+= 365). 相似文献
67.
Changes in the contents of phytate (IP6) and other phosphorus(P)-compoundsin germinating seeds of a huskless barley were investigatedin the embryo with scutellum (EM), the starchy endosperm (EN),and the aleurone layer with pericarp-testa (AL). More than 80%of the total P in the AL of 1-day germinated seeds was foundin acid-soluble organic P, most of which was IP6. During germination,the IP6 in AL decreased markedly with no accumulation of lessphosphorylated myo-inositols and Pi and acid-insoluble organicP increased in the EM. The total P in the EN of 1-day germinatedseeds was about one-third that in the AL, the greater part ofwhich was found in the acid-insoluble fraction and decreasedgradually during germination. Only a small amount of IP6 couldbe detected in the EM and EN during the early stage of germination. IP6 in AL of embryoless half-seeds incubated without gibberellicacid (GA3) decreased slightly even after 6 days. Incubationwith 10 ppm GA3 remarkably stimulated the IP6 degradation. Thisstimulation was reduced, with no change in the Pi content, byabout 8090% with 1 mM 6-methylpurine or 10 ppm cycloheximide.The addition of 0.1 M KH2PO4 caused a 4-fold increase in thePi content of AL in the presence of GA3. In addition, it suppressedthe GA3-dependent -amylase synthesis by about 20% and the GA3effect on IP6 degradation by about 50%. In light of these results, IP6 seems to be hydrolyzed completelyinto Pi and myo-inositol within the aleurone tissue, and gibberellinseems to control this process. (Received August 24, 1979; ) 相似文献
68.
Fusarium solani M-13-1 was shake-cultured in a medium containing guaiacylglycerol-β-coniferyl ether (I), a model compound representing the arylglycerol-β-aryl ether linkage in lignin, as sole carbon source. From the culture filtrate guaiacylglycerol-β-coniferyl aldehyde ether (II) and guaiacylglycerol-β-ferulic acid ether (III) were isolated as metabolic products. Incubation with (III) resulted in formation of guaiacylglycerol-β-vanillin ether (IV), which was further metabolized to guaiacyglycerol-β-vanillic acid ether (V). The results indicate that the cinnamyl alcohol group of (I) is initially oxidized to an aldehyde group, which is further oxidized to a carboxyl group, yielding (II) and (III). Compound (III) is converted to (IV) by the release of a C2 fragment, and the aldehyde group of (IV) is further oxidized to a carboxyl group, giving (V). In the pathway from (I) to (V), neither oxidation of the benzylic secondary alcohol to ketone nor cleavage of the arylglycerol-β-aryl ether linkage was observed. The fungus was found to attack both erythro and threo form without distinction. 相似文献
69.
Small circular DNA complexes in eucaryotic cells 总被引:7,自引:0,他引:7
A small number of eucaryotic cells (100 to 1000 cells) were pressed by mica sheet; then the extruded contents were adsorbed on mica and processed for electron microscopy. In the absence of divalent cation, small polydisperse circular DNA molecules bound to proteins or membrane material were preferentially adsorbed. The small circular DNA complexes have been found in every eucaryotic cell, primary lymphoid tissue cells of bursa and thymus, primary cell lines of retina and liver, and established cultured cell lines of embryonal teratocarcinoma, F9 and PCC3, HeLa and 3T6. Size distribution of these DNA complexes varies, depending on the cell source. The circles less than 1 μm in contour length predominate in cultured cell lines and the larger ones in primary cell lines and cells in situ. Polydisperse covalently closed circular DNAs were recovered from thymus lymphocytes by the conventional dye-CsCl buoyant density method. Their size distribution was similar to that of the small circular DNA complexes detected by the mica-press-adsorption method. They are present in several tens to hundreds of copies per cell representing, at a maximum, 0.02% of the total cellular DNA. The possibility that small circular DNA complexes may result from gene rearrangement as well as from replicon “misfiring” (A. Varshavsky, 1981, Proc. Nat. Acad. Sci. USA 78, 3673–3677) are discussed. 相似文献
70.