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81.
Blatny JM Ventura M Rosenhaven EM Risøen PA Lunde M Brüssow H Nes IF 《Molecular genetics and genomics : MGG》2003,269(4):487-498
82.
Endocytosis of [125I]iodixanol was studied in vivo and in vitro in rat liver cells to determine fluid phase endocytic activity in different liver cells (hepatocytes, Kupffer cells and endothelial cells). The Kupffer cells were more active in the uptake of [l25I]iodixanol than parenchymal cells or endothelial cells. Inhibition of endocytic uptake via clathrin-coated pits (by potassium depletion and hypertonic medium) reduced uptake of [125I]iodixanol much more in Kupffer cells and endothelial cells than in hepatocytes. To gain further information about the importance of clathrin-mediated fluid phase endocytosis, the expression of proteins known to be components of the endocytic machinery was investigated. Using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting, endothelial cells and Kupffer cells were found to express approximately fourfold more rab4, rab5 and rab7 than parenchymal cells, while clathrin was expressed at a higher level in endothelial cells than in Kupffer cells and hepatocytes. Using electron microscopy it was shown that liver endothelial cells contained approximately twice as many coated pits per membrane unit than the parenchymal and Kupffer cells, thus confirming the immunoblotting results concerning clathrin expression. Electron microscopy on isolated liver cells following fluid phase uptake of horseradish peroxidase (HRP) showed that HRP-containing organelles had a different morphology in the different cell types: In the liver endothelial cells HRP was in small, tubular endosomes, while in Kupffer cells HRP was mainly found in larger structures, reminiscent of macropinosomes. Parenchymal cells contained HRP in small vacuolar endosomes with a punctuated distribution. In conclusion, we find that the Kupffer cells and the endothelial cells have a higher pinocytic activity than the hepatocytes. The hepatocytes do, however, account for most of the total hepatic uptake. The fluid phase endocytosis in liver endothelial cells depends mainly on clathrin-mediated endocytosis, while the parenchymal cells have additional clathrin-independent mechanisms that may play an important role in the uptake of plasma membrane components. In the Kupffer cells the major uptake of fluid phase markers seems to take place via a macropinocytic mechanism. 相似文献
83.
Bombesin improves burn-induced intestinal injury in the rat 总被引:4,自引:0,他引:4
This study was designed to determine the effect of exogenous bombesin (10 microg/kg/day, subcutaneously, three times a day) on intestinal hypomotility and neutrophil infiltration in the early and late phases of burn injury (partial-thickness, second-degree burn of the skin). In acute (2 h after burn injury) or chronic (3 days after) burn groups, intestinal transit was delayed, which was reversed by bombesin treatment. In the acute burn group, but not in the chronic group, increased MPO activity was also reduced by bombesin treatment. The results demonstrate that bombesin ameliorates the intestinal inflammation due to burn injury, involving a neutrophil-dependent mechanism. 相似文献
84.
Kinetics of phytate hydrolysis by Aspergillus niger phytase and correlation between the amount of released phosphate and creation of lower myo-inositol phosphates were investigated. Phytase was able to hydrolyze myo-inositol hexakis-, pentakis-, tetrakis-, and trisphosphates. Finally, about 56% of total phosphate were released and myo-inositol bisphosphate was detected as the end-product. 相似文献
85.
Initial events in infectious salmon anemia virus infection: evidence for the requirement of a low-pH step
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Eliassen TM Frøystad MK Dannevig BH Jankowska M Brech A Falk K Romøren K Gjøen T 《Journal of virology》2000,74(1):218-227
We have investigated the initial steps in the interaction between infectious salmon anemia virus (ISAV) and cultured cells from Atlantic salmon (SHK-1 cell line). Using radioactively or fluorescently labelled viral particles we have studied the binding and fusion kinetics and the effect of pH on binding, uptake, and fusion of ISAV to SHK-1 cells and liposomes. As pH in the medium was reduced from 7.5 to 4.5, the association of virus to the cells was nearly doubled. The same effect of pH was observed when fusion between ISAV and liposomes was analyzed. In addition, the binding of ISAV to intact SHK-1 cells and to cell membrane proteins blotted onto filters was neuraminidase sensitive. However, the increased binding induced by low pH was not neuraminidase sensitive, probably reflecting activation of a fusion peptide at low pH. By using confocal fluorescence microscopy, the increased fusion of fluorescently labelled ISAV with the plasma membrane due to low pH could be demonstrated. When vacuolar pH in the cells was raised during inoculation with chloroquine or ammonium chloride, both electron and confocal microscopy showed accumulation of ISAV in endosomes and lysosomes. Production of infectious virus could be increased by lowering the extracellular pH during infection. Furthermore, chloroquine present during virus inoculation also caused a reduction in the synthesis of viral proteins in ISAV-infected cells as well as in the production of infective virus. These results indicate that ISAV binds to sialic acid residues on the cell surface and that the fusion between virus and cell membrane takes place in the acid environment of endosomes. This provides further evidence for a high degree of similarity between ISAV and influenza virus and extends the basis for the classification of this virus as a member of the Orthomyxoviridae family. 相似文献
86.
Fulya Tekşen Bekir Sitki Şayli Ahmet Aydin Ahmet Sayal Aşkin Işimer 《Biological trace element research》1998,63(2):123-127
Down syndrome is the most common cause of mental retardation, affecting 1 in 700–800 liveborn infants. Although numerous biochemical
abnormalities accompanying the syndrome have not yet been completely clarified, the antioxidant defense system enzymes have
shown to be altered due to increased gene dosage on chromosome 21 and overproduction of superoxide dismutase (SOD-1 or Cu/Zn
SOD). The purpose of this study was to investigate the activities of SOD-1 and glutathione peroxidase (GSH-Px) enzymes and
the levels of their cofactors zinc (Zn), copper (Cu) and selenium (Se) in plasma of 20 Down syndrome patients.
In comparison with age and sex-matched controls (n=15), plasma GSH-Px, SOD, and Cu levels were significantly decreased in the patient group, but Zn and Se concentrations remained
unchanged.
This study was presented as a poster in 29th Annual Meeting of European Society of Human Genetics held in Genoa in May, 1997. 相似文献
87.
Şahin Burcu Öztürk Sibel Çalık Pınar Özdamar Tunçer H. 《Bioprocess and biosystems engineering》2015,38(10):1855-1865
Bioprocess and Biosystems Engineering - Defined and semi-defined medium-based feeding strategies were developed to enhance recombinant human growth hormone (rhGH) production by Bacillus subtilis... 相似文献
88.
89.
Nisin production of Lactococcus lactis N8 with hemin‐stimulated cell respiration in fed‐batch fermentation system
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In this study, nisin production of Lactococcus lactis N8 was optimized by independent variables of glucose, hemin and oxygen concentrations in fed‐batch fermentation in which respiration of cells was stimulated with hemin. Response surface model was able to explain the changes of the nisin production of L. lactis N8 in fed‐batch fermentation system with high fidelity (R2 98%) and insignificant lack of fit. Accordingly, the equation developed indicated the optimum parameters for glucose, hemin, and dissolved oxygen were 8 g L?1 h?1, 3 μg mL?1 and 40%, respectively. While 1711 IU mL?1 nisin was produced by L. lactis N8 in control fed‐batch fermentation, 5410 IU mL?1 nisin production was achieved within the relevant optimum parameters where the respiration of cell was stimulated with hemin. Accordingly, nisin production was enhanced 3.1 fold in fed‐batch fermentation using hemin. In conclusion the nisin production of L. lactis N8 was enhanced extensively as a result of increasing the biomass by stimulating the cell respiration with adding the hemin in the fed‐batch fermentation. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:678–685, 2015 相似文献
90.
Elif Şahin Horasan Gülden Ersöz Musa Göksu Feza Otag Ahmet Oner Kurt Sevim Karaçorlu Ali Kaya 《Mycopathologia》2010,170(4):263-268