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When murine T lymphocyte clones were cultured with purified recombinant IL 2, a dose-dependent increase in the production of granulocyte-macrophage colony-stimulating factor (GM-CSF) was observed. Whereas these clones produced both GM-CSF and multi-lineage CSF (multi-CSF) when cultured with concanavalin A, IL 2 induced the production of GM-CSF in the virtual absence of detectable multi-CSF. In addition, IL 2 synergistically enhanced the production of both GM-CSF and multi-CSF by some antigen- or Con-A-stimulated clones. Like Con-A-induced CSF production, GM-CSF production in the presence of IL 2 required protein synthesis but could occur in the absence of proliferation by the clone. Analysis of dose-response curves for stimulation of CSF production by Con A in the presence and absence of IL 2 suggested that Con A and IL 2 activated GM-CSF synthesis by different mechanisms. These results indicate that the coordinate production of two factors by a single T cell clone stimulated with Con A can be dissociated when the clone is stimulated with IL 2. 相似文献
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Stimulator requirements for primed alloreactive T cells: macrophages and dendritic cells activate T cells across all genetic disparities 总被引:3,自引:0,他引:3
G H Sunshine T J Mitchell A A Czitrom S Edwards A L Glasebrook A Kelso H R MacDonald 《Cellular immunology》1985,91(1):60-74
The cellular requirements for stimulating primed alloreactive T cells have been investigated. In vitro-primed secondary alloreactive cells, long-term lines, and Ly 1+2- noncytolytic clones which reacted with allo-H-2K, D, or Mls (M locus) antigens were tested. The data indicated that a specialized antigen-presenting cell such as a macrophage or a dendritic cell was required for stimulating primed alloreactive cells across all the genetic disparities tested. B and T lymphocytes were ineffective stimulators. The stimulator requirement for secondary and Ly 1+2- clone responses was heterogeneous, since both macrophages and dendritic cells were effective stimulators. Thus, the allostimulator requirement for inducing proliferation and mediator secretion by the primed T-cell populations closely paralleled the requirement for stimulating unprimed populations. The only exception found was the peritoneal washout population, which did not stimulate a primary response but did stimulate secondary responses. The failure of peritoneal macrophages to stimulate a primary response was shown to be due to an inhibitory pathway which did not occur when the responding population was alloantigen primed. 相似文献
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We study the dynamics of a system of coupled nonlinear oscillators that has been used to model coordinated human movement behavior. In contrast to earlier work we examine the case where the two component oscillators have different eigenfrequencies. Problems related to the decomposition of a time series (from an experiment) into amplitude and phase are discussed. We show that oscillations at multiples of the main frequency of the oscillator system may occur in the phase and amplitude due to the choice of a coordinate system and how these oscillations can be eliminated. We derive an explicit equation for the dynamics of the relative phase of the oscillator system in phase space that enables a direct comparison between theory and experiment. 相似文献
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Mechanical effects of ET-1 in cardiomyocytes isolated from normal and heart-failed rabbits 总被引:1,自引:0,他引:1
Elizabeth J. Kelso Robert F. Geraghty Barbara J. McDermott Elisabeth R. Trimble D. Paul Nicholls Bernard Silke 《Molecular and cellular biochemistry》1996,157(1-2):149-155
Endothelin (ET-1) is found at elevated concentrations in the plasma of patients with heart failure and in animal models of cardiomyopathy. The peptide is a potent positive inotropic agent, the effects of which are mediated by increases in cytosolic Ca2+ in cardiomyocytes. The object of this study was to investigate at the cellular level, the actions of ET-1 on contractile function and on Ca2+ currents in heart-failed ventricular myocardium. Male New Zealand White rabbits (8 wks) were treated with twice weekly injections of epirubicin (4 mg/kg/wk, n=7) or with saline (n=7) for 6 wks, followed by a washout period of 2 wks. Ventricular cardiomyocytes were isolated from rabbit hearts using Langendorff perfusion with collagenase; contractile function was examined using a video microscopy method, and L-type Ca2+ currents were recorded using a whole-cell patch-clamp technique. ET-1 produced a concentration-dependent increase in contractile response (% increase from basal value) to a maximum at 1 nM ET-1 of 69 ± 11% (mean ± S.D.) in control cardiomyocytes and 33 ± 6% in heart-failed cells. However, there was no significant change in the EC50 obtained with ET-1 for healthy (0.31 ± 0.1 nM) and for failed cardiomyocytes (0.24 ± 0.1 nM). The effects of ET-1 on L-type Ca2+ channels were similar with a peak amplitude at 1 nM ET-1 of –3.26 ± 0.8 in control cardiomyocytes and –3.32 ± 0.9 nA in heart-failed cells. The attenuation of the contractile response to ET-1 in heart-failed cells may reflect a desensitization of ET receptors as a consequence of elevated circulating levels of ET and was not reflected by alteration of transmembrane Ca2+ conductance. It is probable, therefore, that multiple signalling pathways are involved in the actions of ET on ventricular myocardium.Recipient of Servier Investigator Award 相似文献
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Loic Giot Michel Simon Celine Dubois Gerard Faye 《Molecular genetics and genomics : MGG》1995,246(2):212-222
DNA polymerases (Pol) α, δ and ε are necessary for replication of nuclear DNA. Po1δ interacts permanently or transiently with numerous accessory proteins whose identification may shed light on the function(s) of Po18. In vitro mutagenesis was used to induce thermosensitive (ts) mutations in the DNA polymerase δ gene (POL3). We have attempted to clone two recessive extragenic suppressors of such is mutants (sdp1 for mutation pol3-14 and sdp5-1 for mutation pol3-11) by transforming thermoresistant haploid strains pol3-14 sdpl and pol3-11 sdp5-1 with wild-type genomic libraries in singlecopy or multicopy vectors. None of the thermosensitive transformants so obtained was identified as being sdp1 or sdp5-1. Instead, three genes were cloned whose products interfere with the activity of suppressors. One of them is the type 1 protein phosphatase gene, D1S2. Another is a novel gene, ASM4, whose gene product is rich in asparagine and glutamine residues. 相似文献
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The ammonia oxidizing bacterium Nitrosomonas europaea was grown either (a) with added bicarbonate in the absence of added CO2 (bubbled through the culture), (b) with added bicarbonate plus low added CO2 (0.03% v/v), or (c) without added bicarbonate with high added CO2 (1% v/v). Cell doubling times of 12 h were observed in 1% cultures; doubling times of 2 to 3-fold longer wre found with 0.03% CO2 and/or bicarbonate grown cultures. The specific activity of carbonic anhydrase was 40–80% lower in cultures grown on 1% CO2. These results are compared with those in heterotrophic and photosynthetic microorganisms.Scientific Contribution Number 1241 from the New Hampshire Agricultural Experiment Station 相似文献