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排序方式: 共有218条查询结果,搜索用时 15 毫秒
71.
Weinman EJ Steplock D Shenolikar S Blanpied TA 《American journal of physiology. Renal physiology》2011,300(1):F231-F235
Parathyroid hormone (PTH) inhibits the reabsorption of phosphate in the renal proximal tubule by disrupting the binding of the sodium-dependent phosphate transporter 2A (Npt2a) to the adapter protein sodium-hydrogen exchanger regulatory factor-1 (NHERF-1), a process initiated by activation of protein kinase C (PKC). To gain additional insights into the dynamic sequence of events, the time course of these responses was studied in living opossum kidney (OK) cells. Using a FRET-based biosensor, we found that PTH activated intracellular PKC within seconds to minutes. In cells expressing GFP-Npt2a and mCherry-NHERF, PTH did not affect the relative abundance of NHERF-1 but there was a significant and time-dependent decrease in the Npt2a/NHERF-1 ratio. The half-time to maximal dissociation was 15 to 20 min. By contrast, PTH had no effect on the fluorescence ratio for GFP-ezrin compared with mCherry-NHERF-1 at the apical surface. These experiments establish that PTH treatment of proximal tubule OK cells leads to rapid activation of PKC with the subsequent dissociation of Npt2a/NHERF-1 complexes. The association of NHERF-1 with Ezrin and their localization at the apical membrane, however, was unperturbed by PTH, thereby enabling the rapid recruitment and membrane reinsertion of Npt2a and other NHERF-1 targets on termination of the hormone response. 相似文献
72.
73.
CJ Cooksey 《Biotechnic & histochemistry》2014,89(8):564-567
Trypan blue is colorant from the 19th century that has an association with Africa as a chemotherapeutic agent against protozoan (Trypanosomal) infections, which cause sleeping sickness. The dye still is used for staining biopsies, living cells and organisms, and it also has been used as a colorant for textiles. 相似文献
74.
Emily Clausen Catherine Wittman Matthew Gingo Khaled Fernainy Carl Fuhrman Cathy Kessinger Renee Weinman Deborah McMahon Joseph Leader Alison Morris 《PloS one》2014,9(11)
Background
Chest radiographic abnormalities were common in HIV-infected individuals in the pre-combination antiretroviral therapy era, but findings may differ now due to a changing spectrum of pulmonary complications.Methods
Cross-sectional study of radiographic abnormalities in an HIV-infected outpatient population during the antiretroviral therapy era. Demographics, chest computed tomography, and pulmonary function tests were obtained in HIV-infected volunteers without acute respiratory illness from the University of Pittsburgh HIV/AIDS clinic. Overall prevalence of radiographic abnormalities and potential risk factors for having any abnormality, nodules, or emphysema were evaluated using univariate and multivariable analyses.Results
A majority of the 121 participants (55.4%) had a radiographic abnormality with the most common being emphysema (26.4%), nodules (17.4%), and bronchiectasis (10.7%). In multivariate models, age (odds ratio [OR] per year = 1.07, 95% confidence interval [CI] 1.04–1.14, p<0.001), pneumonia history (OR = 3.60, 95% CI = 1.27–10.20, p = 0.016), and having ever smoked (OR = 3.66, p = 0.013, 95% CI = 1.31–10.12) were significant predictors of having any radiographic abnormality. Use of antiretroviral therapy, CD4 cell count, and HIV viral load were not associated with presence of abnormalities. Individuals with radiographic emphysema were more likely to have airway obstruction on pulmonary function tests. Only 85.8% participants with nodules had follow-up imaging resulting in 52.4% having stable nodules, 23.8% resolution of their nodules, 4.8% development of a new nodule, and 4.8% primary lung cancer.Conclusions
Radiographic abnormalities remain common in HIV-infected individuals with emphysema, nodules, and bronchiectasis being the most common. Age, smoking, and pneumonia were associated with radiographic abnormalities, but HIV-associated factors did not seem to predict risk. 相似文献75.
Maarten van den Berge Wim CJ Hop Thys van der Molen Jan A van Noord Jacques PHM Creemers Ad JM Schreurs Emiel FM Wouters Dirkje S Postma 《Respiratory research》2012,13(1):44
Background
Frequent exacerbations induce a high burden to Chronic Obstructive Pulmonary Disease (COPD). We investigated the course of exacerbations in the published COSMIC study that investigated the effects of 1-year withdrawal of fluticasone after a 3-month run-in treatment period with salmeterol/fluticasone in patients with COPD.Methods
In 373 patients, we evaluated diary cards for symptoms, Peak Expiratory Flow (PEF), and salbutamol use and assessed their course during exacerbations.Results
There were 492 exacerbations in 224 patients. The level of symptoms of cough, sputum, dyspnea and nocturnal awakening steadily increased from 2 weeks prior to exacerbation, with a sharp rise during the last week. Symptoms of cough, sputum, and dyspnea reverted to baseline values at different rates (after 4, 4, and 7 weeks respectively), whereas symptoms of nocturnal awakening were still increased after eight weeks. The course of symptoms was similar around a first and second exacerbation. Increases in symptoms and salbutamol use and decreases in PEF were associated with a higher risk to develop an exacerbation, but with moderate predictive values, the areas under the receiver operating curves ranging from 0.63 to 0.70.Conclusions
Exacerbations of COPD are associated with increased symptoms that persist for weeks and the course is very similar between a first and second exacerbation. COPD exacerbations are preceded by increased symptoms and salbutamol use and lower PEF, yet predictive values are too low to warrant daily use in clinical practice. 相似文献76.
Lonneke Smeding Frans B Pl?tz Regis R Lamberts Willem J van der Laarse Martin CJ Kneyber AB Johan Groeneveld 《Respiratory research》2012,13(1):23
Background
Injurious mechanical ventilation (MV) may augment organ injury remote from the lungs. During sepsis, myocardial dysfunction is common and increased endothelial activation and permeability can cause myocardial edema, which may, among other factors, hamper myocardial function. We investigated the effects of MV with injuriously high tidal volumes on the myocardium in an animal model of sepsis.Methods
Normal rats and intraperitoneal (i.p.) lipopolysaccharide (LPS)-treated rats were ventilated with low (6 ml/kg) and high (19 ml/kg) tidal volumes (Vt) under general anesthesia. Non-ventilated animals served as controls. Mean arterial pressure (MAP), central venous pressure (CVP), cardiac output (CO) and pulmonary plateau pressure (Pplat) were measured. Ex vivo myocardial function was measured in isolated Langendorff-perfused hearts. Cardiac expression of endothelial vascular cell adhesion molecule (VCAM)-1 and edema were measured to evaluate endothelial inflammation and leakage.Results
MAP decreased after LPS-treatment and Vt-dependently, both independent of each other and with interaction. MV Vt-dependently increased CVP and Pplat and decreased CO. LPS-induced peritonitis decreased myocardial function ex vivo but MV attenuated systolic dysfunction Vt-dependently. Cardiac endothelial VCAM-1 expression was increased by LPS treatment independent of MV. Cardiac edema was lowered Vt-dependently by MV, particularly after LPS, and correlated inversely with systolic myocardial function parameters ex vivo.Conclusion
MV attenuated LPS-induced systolic myocardial dysfunction in a Vt-dependent manner. This was associated with a reduction in cardiac edema following a lower transmural coronary venous outflow pressure during LPS-induced coronary inflammation. 相似文献77.
78.
79.
A covariotide model explains apparent phylogenetic structure of oxygenic photosynthetic lineages 总被引:17,自引:13,他引:4
Lockhart PJ; Steel MA; Barbrook AC; Huson DH; Charleston MA; Howe CJ 《Molecular biology and evolution》1998,15(9):1183-1188
The aims of the work were (1) to develop statistical tests to identify
whether substitution takes place under a covariotide model in sequences
used for phylogenetic inference and (2) to determine the influence of
covariotide substitution on phylogenetic trees inferred for photosynthetic
and other organisms. (Covariotide and covarion models are ones in which
sites that are variable in some parts of the underlying tree are invariable
in others and vice versa.) Two tests were developed. The first was a
contingency test, and the second was an inequality test comparing the
expected number of variable sites in two groups with the observed number.
Application of these tests to 16S rDNA and tufA sequences from a range of
nonphotosynthetic prokaryotes and oxygenic photosynthetic prokaryotes and
eukaryotes suggests the occurrence of a covariotide mechanism. The degree
of support for partitioning of taxa in reconstructed trees involving these
organisms was determined in the presence or absence of sites showing
particular substitution patterns. This analysis showed that the support for
splits between (1) photosynthetic eukaryotes and prokaryotes and (2)
photosynthetic and nonphotosynthetic organisms could be accounted for by
patterns arising from covariotide substitution. We show that the additional
problem of compositional bias in sequence data needs to be considered in
the context of patterns of covariotide/covarion substitution. We argue that
while covariotide or covarion substitution may give rise to
phylogenetically informative patterns in sequence data, this may not always
be so.
相似文献
80.
Na+-H+ exchange and Na+ entry across the apical membrane of Necturus gallbladder 总被引:9,自引:8,他引:1
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The role of Na+-H+ exchange in Na+ transport across the apical membrane was evaluated in Necturus gallbladder epithelium by means of intracellular Na+ activity (aNai) and 22Na+ uptake measurements. Under control conditions, complete replacement of Na+ in the mucosal solution with tetramethylammonium reduced aNai from 14.0 to 6.9 mM in 2 min (P less than 0.001). Mucosal addition of the Na+-H+ exchange inhibitor amiloride (10(-3) M) reduced aNai from 15.0 to 13.3 mM (P less than 0.001), whereas bumetanide (10(-5) and 10(-4) M) had no effect. Na+ influx across the apical membrane was studied by treating the tissues with ouabain, bathing them in Na-free solutions, and suddenly replacing the mucosal solution with an Na-containing solution. When the mucosal solution was replaced with Na-Ringer's, aNai increased at approximately 11 mM/min. This increase was inhibited by 54% by amiloride (10(-3) M, P less than 0.001) and was unaffected by bumetanide (10(-5) M). Amiloride-inhibitable Na+ fluxes across the apical membrane were also induced by the imposition of pH gradients. Na+ influx was also examined in tissues that had not been treated with ouabain. Under control conditions, 22Na+ influx from the mucosal solution into the epithelium was linear over the first 60 s and was inhibited by 40% by amiloride (10(-3) M, P less than 0.001) and by 19% by bumetanide (10(-5) M, P less than 0.025). We conclude that Na+-H+ exchange is a major pathway for Na+ entry in Necturus gallbladder, which accounts for at least half of apical Na+ influx both under transporting conditions and during exposure to ouabain. Bumetanide-inhibitable Na+ entry mechanisms may account for only a smaller fraction of Na+ influx under transporting conditions, and cannot explain influx in ouabain-treated tissues. These results support the hypothesis that NaCl entry results primarily from the operation of parallel Na+-H+ and Cl--HCO-3 exchangers, and not from a bumetanide-inhibitable NaCl cotransporter. 相似文献