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41.
Monoclonal antibody-mediated inhibition of interferon-gamma-induced macrophage antiviral resistance and surface antigen expression 总被引:3,自引:0,他引:3
S N Vogel E A Havell G L Spitalny 《Journal of immunology (Baltimore, Md. : 1950)》1986,136(8):2917-2923
A monoclonal antibody (MAb) with specificity for murine interferon-gamma (IFN-gamma) was used as a probe for studying the effect of recombinant IFN-gamma (rIFN-gamma) on antiviral activity, Fc receptor expression, and Ia antigen induction in macrophages. Cultures of C3H/HeJ peritoneal exudate macrophages were used to allow direct comparison of all three functions in the same target cell system. Our data provide two major findings: the efficacy of the MAb is very different depending on whether murine fibroblasts or macrophages are used as the target cell in the antiviral assay, i.e., greater than 20 to 100 times more MAb was required to block antiviral activity in macrophage cultures; and 10 to 50 times more MAb was required to inhibit Fc receptor vs Ia antigen expression in response to rIFN-gamma. These latter findings confirm and extend previous observations, which indicate that the induction pathways of two important differentiation markers by IFN-gamma may be dissociable. 相似文献
42.
Endoreduplication was induced in V 79 cells using Colcemid. The concentration of Colcemid necessary to induce endoreduplication is about 1000 times higher than that needed to arrest mitoses or to induce ordinary tetraploid cells. Diplochromosomes with sister chromatid differentiation were obtained by adding BrdU for the duration of one cell cycle prior to the induction of endoreduplication. The induction of endoreduplication with Colcemid had no influence on the frequency of sister chromatid exchanges (SCEs). Treating the cultures with mitomycin C (MMC) before adding BrdU increased the percentage of endoreduplieated mitoses and also led to marked SCE induction. In the diplochromosomes, the frequencies of both twin SCEs (first cycle) as well as single SCEs (second cycle) were increased. It was also found that the SCE frequencies in mitoses after endoreduplication were lower than the values found in diploid and ordinary tetraploid metaphases of the same preparation. The possible conclusions concerning the lifetime of SCE-inducing lesions and the influence of repair processes are discussed. 相似文献
43.
Bone marrow-derived macrophages: development and regulation of differentiation markers by colony-stimulating factor and interferons 总被引:17,自引:0,他引:17
To investigate the role of specific cytokines in the development of the fully mature macrophage, we have employed murine bone marrow cells that were grown in the presence of CSF-1, a colony-stimulating factor that has been shown to induce the proliferation and differentiation of macrophages from their precursor cells. The CSF-1 employed in these studies was partially purified to ensure removal of contaminating interferon (IFN) from the preparations. After 1 to 2 wk in the presence of the partially purified CSF-1, the adherent macrophages were removed from flasks enzymatically and were recultured at known densities in the absence of CSF-1. Cell surface antigens (Mac-1 and Ia) and Fc receptor capacity (as assessed by Fc-mediated phagocytosis) were examined as markers of macrophage differentiation. Basal levels of Fc receptor capacity and Mac-1 antigen were markedly influenced by exposure to CSF-1, and appear to be modulated by CSF-induced, macrophage-derived IFN. When the bone marrow-derived macrophages were exposed to exogenous IFN in the absence of CSF-1, they proved to be extremely inducible with respect to Fc-mediated phagocytosis (IFN-beta and rIFN-gamma) and Ia antigen expression (rIFN-gamma) when compared with thioglycollate-elicited macrophages. Thus, macrophage growth factors, such as CSF-1, promote macrophage maturation by inducing the production of autostimulatory signals, such as macrophage-derived IFN. In addition, exogenous cytokine stimuli, such as IFN-gamma, further amplify the differentiative potential of these cells. Bone marrow-derived macrophages, propagated under well-defined conditions and never exposed to eliciting agents, provide a powerful model for studying the role of cytokines, such as CSF-1 and IFN, in the differentiative pathway of macrophages. 相似文献
44.
Antagonistic effect of interferon-beta on the interferon-gamma-induced expression of Ia antigen in murine macrophages 总被引:5,自引:0,他引:5
The cell surface expression of I region-associated (Ia) antigens by murine and human macrophages has been shown by investigators from a number of laboratories to be induced in a dose-dependent fashion by IFN-gamma, which is free of other lymphokines. The experiments described in this report demonstrate that fibroblast-derived IFN-beta exerts an antagonistic effect on IFN-gamma induced Ia expression in murine macrophages. Simultaneous addition of IFN-beta and IFN-gamma to peritoneal exudate macrophages results in decreased Ia expression when compared with macrophages treated with IFN-gamma only. Different sources of highly purified IFN-beta, as well as a recombinant human IFN-alpha (A/D Bgl; shown previously to be as active as IFN-beta in several other murine systems) acted in a similar antagonistic fashion to IFN-gamma-induced Ia induction. The down-regulation of Ia expression by IFN-beta is dose-dependent over a concentration range up to 100 U/ml. Time-course experiments indicated that for IFN-beta to down-regulate IFN-gamma-induced Ia, it had to be present either before stimulation with IFN-gamma or during the first 24 hr of simultaneous stimulation. Further experiments in which a highly specific antibody against IFN-alpha/beta was added to the cultures confirmed the findings of the time-course experiments. Inhibitors of the arachidonic acid pathway failed to reverse the effect of IFN-beta to reduce Ia antigen expression, which suggests that this inhibition is not prostaglandin mediated. Thus, these findings support a role for type I IFN as naturally occurring substances that negatively regulate the expression of class II molecules. 相似文献
45.
Forty-one amino acids and related compounds were measured (using an HPLC physiological amino acid analysis procedure fully validated for plasma studies) in rat plasma obtained through an indwelling jugular catheter before, during and following a 30 min period of immobilization. Taurine, phosphoethanolamine, aspartic acid, glutamic acid, alanine, cystine, tyrosine, beta-alanine and ethanolamine were increased during the period of stress; whereas, valine, tryptophan and arginine were decreased. Most of these alterations were restored toward normal during the 30 min of rest following the stress period. However, cystine, ethanolamine and beta-alanine remained significantly elevated, and valine, tryptophan and arginine remained significantly reduced. Serine, isoleucine, leucine and glutamine were not significantly altered during the stress period, but became significantly reduced during the 30 min following the stress period. While the patterns of amino acid alterations were generally consistent from animal to animal, the magnitude of the responses were variable with some rats demonstrating much larger responses than others. These results may implicate amino acids as important markers for stress related pathologies. The individual differences noticed may explain why some individuals show more stress effects than others. 相似文献
46.
Characterization of proteoglycans from adult bovine tendon 总被引:9,自引:0,他引:9
Proteoglycans were extracted in good yield from the proximal, fibrous portion of adult bovine tendon with 4 m guanidine HCl. They comprise less than 1% of the dry weight of the tissue. Using CsCl density gradient centrifugation, gel chromatography, and ion exchange chromatography, two populations of proteoglycans were separated and purified from other tissue proteins. One was a large, chondroitin sulfate proteoglycan with high buoyant density in CsCl. This component appeared to be composed of two or three subpopulations as detected by agarose/polyacrylamide electrophoresis, although they could not be effectively separated from one another for individual characterization. As a group, the large proteoglycans eluted from Sepharose CL-2B with Kav from 0.1-0.5 and their core protein had Mr greater than 200,000 with high contents of glutamic acid, serine, and glycine. The glycosaminoglycan chains had a weight average Mr of 17,000 and more than 98% of the uronic acid was glucuronic acid. This group comprised only 12% of the total proteoglycan of the tissue. The other 88% of the proteoglycans appeared to represent one group of small molecules that eluted from Sepharose CL-2B at Kav = 0.70. They demonstrated buoyant densities in a CsCl gradient ranging from greater than or equal to 1.51 to 1.30 g/ml. Their core protein had an apparent Mr = 48,000 following removal of the glycosaminoglycan chains by digestion with chondroitinase ABC. This core protein had a particularly high content of aspartic acid/asparagine and leucine. The glycosaminoglycan chains had a weight average Mr of 37,000 and were dermatan sulfate containing 73% iduronic acid. Those molecules found at highest buoyant density appeared to have additional glycosaminoglycan chains that were shorter. Proteoglycans were also extracted from the pressure-bearing distal region of this tendon, where contents of proteoglycan per wet weight of tissue were 3-fold higher and as much as 50% of this was as large as the large proteoglycans from the proximal tissue. Preparations of large proteoglycans from both tendon regions contained molecules capable of interacting with hyaluronic acid. 相似文献
47.
The binding of copper(II) and zinc(II) to oxidized glutathione 总被引:1,自引:0,他引:1
1H and 13C NMR studies of Zn(II) binding to oxidized glutathione (GSSG) in aqueous solution over the pH range 4-11 show that it forms a complex with a 1:1 Zn:GSSG stoichiometry. At pH values between 6 and 11 the metal ligands are the COO- and NH2 groups of the glutamate residues. Below pH 5 the glycine end of the molecule also binds to the metal ions. EPR and visible absorption spectra of Cu(II) GSSG solutions suggest that similar complexes are formed with Cu(II). The solid products obtained from these solutions are shown by analysis and EPR to be primarily binuclear with Cu2GSSG stoichiometry, although the structures depend on the pH and stoichiometry of the solution from which they were obtained. 相似文献
48.
The structure of the lactose permease derived from Raman spectroscopy and prediction methods. 总被引:22,自引:1,他引:21
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The secondary structure of the lactose permease of Escherichia coli reconstituted in lipid membranes was determined by Raman spectroscopy. The alpha-helix content is approximately 70%, the beta-strand content below 10% and beta-turns contribute 15%. About 1/3 of the residues in alpha-helices and most other residues are exposed to water. Employing a method for structural prediction which accounts for amphipathic helices, 10 membrane-spanning helices are predicted which are either hydrophobic or amphipathic. They are expected to form an outer ring of helices in the membrane. The interior of the ring would be made of residues which are predominantly hydrophilic and, evoking the analogy to sugar-binding proteins, suited to provide the sugar binding site. 相似文献
49.
A comparative description of mitochondrial DNA differentiation in selected avian and other vertebrate genera 总被引:14,自引:1,他引:13
Levels of mitochondrial DNA (mtDNA) sequence divergence between species
within each of several avian (Anas, Aythya, Dendroica, Melospiza, and
Zonotrichia) and nonavian (Lepomis and Hyla) vertebrate genera were
compared. An analysis of digestion profiles generated by 13-18 restriction
endonucleases indicates little overlap in magnitude of mtDNA divergence for
the avian versus nonavian taxa examined. In 55 interspecific comparisons
among the avian congeners, the fraction of identical fragment lengths (F)
ranged from 0.26 to 0.96 (F = 0.46), and, given certain assumptions, these
translate into estimates of nucleotide sequence divergence (p) ranging from
0.007 to 0.088; in 46 comparisons among the fish and amphibian congeners, F
values ranged from 0.00 to 0.36 (F = 0.09), yielding estimates of P greater
than 0.070. The small mtDNA distances among avian congeners are associated
with protein-electrophoretic distances (D values) less than approximately
0.2, while the mtDNA distances among assayed fish and amphibian congeners
are associated with D values usually greater than 0.4. Since the
conservative pattern of protein differentiation previously reported for
many avian versus nonavian taxa now appears to be paralleled by a
conservative pattern of mtDNA divergence, it seems increasingly likely that
many avian species have shared more recent common ancestors than have their
nonavian taxonomic counterparts. However, estimates of avian divergence
times derived from mtDNA- and protein-calibrated clocks cannot readily be
reconciled with some published dates based on limited fossil remains. If
the earlier paleontological interpretations are valid, then protein and
mtDNA evolution must be somewhat decelerated in birds. The empirical and
conceptual issues raised by these findings are highly analogous to those in
the long-standing debate about rates of molecular evolution and times of
separation of ancestral hominids from African apes.
相似文献
50.
Methods for computing the standard errors of branching points in an evolutionary tree and their application to molecular data from humans and apes 总被引:23,自引:2,他引:21
Statistical methods for computing the standard errors of the branching
points of an evolutionary tree are developed. These methods are for the
unweighted pair-group method-determined (UPGMA) trees reconstructed from
molecular data such as amino acid sequences, nucleotide sequences,
restriction-sites data, and electrophoretic distances. They were applied to
data for the human, chimpanzee, gorilla, orangutan, and gibbon species.
Among the four different sets of data used, DNA sequences for an
895-nucleotide segment of mitochondrial DNA (Brown et al. 1982) gave the
most reliable tree, whereas electrophoretic data (Bruce and Ayala 1979)
gave the least reliable one. The DNA sequence data suggested that the
chimpanzee is the closest and that the gorilla is the next closest to the
human species. The orangutan and gibbon are more distantly related to man
than is the gorilla. This topology of the tree is in agreement with that
for the tree obtained from chromosomal studies and DNA-hybridization
experiments. However, the difference between the branching point for the
human and the chimpanzee species and that for the gorilla species and the
human-chimpanzee group is not statistically significant. In addition to
this analysis, various factors that affect the accuracy of an estimated
tree are discussed.
相似文献