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111.
Fluorescence recovery after photobleaching (FRAP) has become a popular technique to investigate the behavior of proteins in living cells. Although the technique is relatively old, its application to studying endogenous intracellular proteins in living cells is relatively recent and is a consequence of the newly developed fluorescent protein-based living cell protein tags. This is particularly true for nuclear proteins, in which endogenous protein mobility has only recently been studied. Here we examine the experimental design and analysis of FRAP experiments. Mathematical modeling of FRAP data enables the experimentalist to extract information such as the association and dissociation constants, distribution of a protein between mobile and immobilized pools, and the effective diffusion coefficient of the molecule under study. As experimentalists begin to dissect the relative influence of protein domains within individual proteins, this approach will allow a quantitative assessment of the relative influences of different molecular interactions on the steady-state distribution and protein function in vivo. 相似文献
112.
I Carrero M D Fernández-Moreno M A Pérez-Albarsanz J C Prieto 《Biochemical and biophysical research communications》1989,159(3):1391-1396
Isolated rat enterocytes exposed to the insecticide lindane (the gamma-isomer of hexachlorocyclohexane, HCCH) showed an important decrease in the efficiency of the neuropeptide vasoactive intestinal peptide (VIP) upon the stimulation of cyclic AMP accumulation. The effect of lindane was time- and dose-dependent, optimal conditions being reached after 5 min incubation of cells at 25 degrees C with 0.5 mM of this organochlorine compound. Lindane action exhibited an important degree of specificity since the isomer alpha-HCCH and endrin reproduced the same inhibitory pattern but beta-HCCH and dieldrin were inactive. The inhibition of VIP-induced cyclic AMP accumulation could not be explained by a lindane-dependent reduction in the binding of VIP to its specific receptors. Among various possibilities, the results suggest the modification of membrane fluidity by lindane and/or the activation of Ca2+-dependent protein kinase C by this compound leading to phosphorylation of Gs/adenylate cyclase. 相似文献
113.
114.
The study focuses on the mechanisms of endothelial dysfunction in the uremic milieu. Subcutaneous resistance arteries from 35 end-stage renal disease (ESRD) patients and 28 matched controls were studied ex-vivo. Basal and receptor-dependent effects of endothelium-derived factors, expression of endothelial NO synthase (eNOS), prerequisites for myoendothelial gap junctions (MEGJ), and associations between endothelium-dependent responses and plasma levels of endothelial dysfunction markers were assessed. The contribution of endothelium-derived hyperpolarizing factor (EDHF) to endothelium-dependent relaxation was impaired in uremic arteries after stimulation with bradykinin, but not acetylcholine, reflecting the agonist-specific differences. Diminished vasodilator influences of the endothelium on basal tone and enhanced plasma levels of asymmetrical dimethyl L-arginine (ADMA) suggest impairment in NO-mediated regulation of uremic arteries. eNOS expression and contribution of MEGJs to EDHF type responses were unaltered. Plasma levels of ADMA were negatively associated with endothelium-dependent responses in uremic arteries. Preserved responses of smooth muscle to pinacidil and NO-donor indicate alterations within the endothelium and tolerance of vasodilator mechanisms to the uremic retention products at the level of smooth muscle. We conclude that both EDHF and NO pathways that control resistance artery tone are impaired in the uremic milieu. For the first time, we validate the alterations in EDHF type responses linked to kinin receptors in ESRD patients. The association between plasma ADMA concentrations and endothelial function in uremic resistance vasculature may have diagnostic and future therapeutic implications. 相似文献
115.
Manminder Kaur Lucy JC Smyth Paul Cadden Seamus Grundy David Ray Jonathan Plumb Dave Singh 《Respiratory research》2012,13(1):20
Background
There are increased numbers of activated lymphocytes in the lungs of chronic obstructive pulmonary disease (COPD) patients. The clinical benefits of corticosteroids in COPD patients are limited. Our hypothesis is that lymphocytes play a role in this corticosteroid insensitivity.Objectives
To investigate the effects of the corticosteroid dexamethasone on lung lymphocyte cytokine production from patients with COPD compared to controls.Methods
Cultured airway lymphocytes obtained by bronchoscopy from healthy non-smokers (HNS), smokers (S) and COPD patients were stimulated with phytohaemagglutinin (PHA) & phorbol myristate acetate (PMA), +/- dexamethasone. Supernatants were assayed for interleukin (IL)-2 and interferon (IFN)γ. Immunofluoresence was used to analyse changes in CD8 glucocorticoid receptor (GRα and GRβ) expression.Results
The inhibition of PHA/PMA stimulated IFNγ production by dexamethasone was reduced in COPD patients compared to HNS (p < 0.05 at concentrations from 0.1-1 μM). There was also a significant reduction (p < 0.05) in the mean inhibitory effect at 1 μM in COPD patients (54.1%) compared to smokers (72.1%), and in smokers compared to HNS (85.5%). There was a numerically reduced effect of dexamethasone on IL-2 production that did not reach statistical significance. There was no difference in GRα and GRβ expression in follicular CD8 cells between COPD patients (50.9% and 30.4% respectively) and smokers (52.9% and 29.7% respectively).Conclusions
IFNγ production from COPD airway lymphocytes is corticosteroid insensitive. This phenomenon may be important in the poor clinical response often observed with corticosteroids. 相似文献116.
The presentation of microbial protein antigens by Major Histocompatibility Complex (MHC) molecules is essential for the development of acquired immunity to infections. However, most biochemical studies of antigen processing and presentation deal with a few relatively inert non-microbial model antigens. The bacterial pore-forming toxin listeriolysin O (LLO) is paradoxical in that it is cytotoxic at nanomolar concentrations as well as being the source of dominant CD4 and CD8 T cell epitopes following infection with Listeria monocytogenes. Here, we examined the relationship of LLO toxicity to its antigenicity and immunogenicity. LLO offered to antigen presenting cells (APC) as a soluble protein, was presented to CD4 T cells at picomolar to femtomolar concentrations- doses 3000-7000-fold lower than free peptide. This presentation required a dose of LLO below the cytotoxic level. Mutations of two key tryptophan residues reduced LLO toxicity by 10-100-fold but had no effect on its presentation to CD4 T cells. Thus there was a clear dissociation between the cytotoxic properties of LLO and its very high antigenicity. Presentation of LLO to CD8 T cells was not as robust as that seen in CD4 T cells, but still occurred in the nanomolar range. APC rapidly bound and internalized LLO, then disrupted endosomal compartments within 4 hours of treatment, allowing endosomal contents to access the cytosol. LLO was also immunogenic after in vivo administration into mice. Our results demonstrate the strength of LLO as an immunogen to both CD4 and CD8 T cells. 相似文献
117.
Background
Intoxication from the psychostimulant methamphetamine (METH) because of cardiovascular collapse is a common cause of death within the abuse population. For obvious reasons, the heart has been taken as the primary target for this METH-induced toxicity. The demonstration that failure of brain stem cardiovascular regulation, rather than the heart, holds the key to cardiovascular collapse induced by the pesticide mevinphos implicates another potential underlying mechanism. The present study evaluated the hypothesis that METH effects acute cardiovascular depression by dampening the functional integrity of baroreflex via an action on brain stem nuclei that are associated with this homeostatic mechanism. 相似文献118.
Kieran Hyder Alberto Vidal-Diez Joanna Lawes A Robin Sayers Ailsa Milnes Linda Hoinville Alasdair JC Cook 《BMC veterinary research》2011,7(1):14
Background
New and emerging diseases of livestock may impact animal welfare, trade and public health. Early detection of outbreaks can reduce the impact of these diseases by triggering control measures that limit the number of cases that occur. The aim of this study was to investigate whether prospective spatiotemporal methods could be used to identify outbreaks of new and emerging diseases in scanning surveillance data. SaTScan was used to identify clusters of unusually high levels of submissions where a diagnosis could not be reached (DNR) using different probability models and baselines. The clusters detected were subjected to a further selection process to reduce the number of false positives and a more detailed epidemiological analysis to ascertain whether they were likely to represent real outbreaks. 相似文献119.
Inhaled corticosteroids (ICS) reduce COPD exacerbation frequency and slow decline in health related quality of life but have little effect on lung function, do not reduce mortality, and increase the risk of pneumonia. We systematically reviewed trials in which ICS have been withdrawn from patients with COPD, with the aim of determining the effect of withdrawal, understanding the differing results between trials, and making recommendations for improving methodology in future trials where medication is withdrawn. Trials were identified by two independent reviewers using MEDLINE, EMBASE and CINAHL, citations of identified studies were checked, and experts contacted to identify further studies. Data extraction was completed independently by two reviewers. The methodological quality of each trial was determined by assessing possible sources of systematic bias as recommended by the Cochrane collaboration. We included four trials; the quality of three was adequate. In all trials, outcomes were generally worse for patients who had had ICS withdrawn, but differences between outcomes for these patients and patients who continued with medication were mostly small and not statistically significant. Due to data paucity we performed only one meta-analysis; this indicated that patients who had had medication withdrawn were 1.11 (95% CI 0.84 to 1.46) times more likely to have an exacerbation in the following year, but the definition of exacerbations was not consistent between the three trials, and the impact of withdrawal was smaller in recent trials which were also trials conducted under conditions that reflected routine practice. There is no evidence from this review that withdrawing ICS in routine practice results in important deterioration in patient outcomes. Furthermore, the extent of increase in exacerbations depends on the way exacerbations are defined and managed and may depend on the use of other medication. In trials where medication is withdrawn, investigators should report other medication use, definitions of exacerbations and management of patients clearly. Intention to treat analyses should be used and interpreted appropriately. 相似文献
120.
Norbert Meyer Jan W Dallinga Sarah Janine Nuss Edwin JC Moonen Joep JBN van Berkel Cezmi Akdis Frederik Jan van Schooten Günter Menz 《Respiratory research》2014,15(1)