Membrane Impermeability
Mostrando 1-12 de 28 artigos, teses e dissertações.
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1. Caracterização molecular da resistência aos carbapenêmicos em enterobactérias isoladas em hospitais brasileiros / Molecular characterization of carbapenem resistance in enterobacteria isolated in Brazilian hospitals
Introdução: Após o surgimento e disseminação das β-lactamases (BL) de amplo espectro em membros da família Enterobacteriaceae, os antibióticos carbapenêmicos (imipenem, meropenem, ertapenem) têm sido considerados a terapia de escolha pela estabilidade apresentada contra estas enzimas. Infelizmente, em 2005, o primeiro caso de infecção fatal p
Publicado em: 2009
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2. Regulation of Membrane Permeability by a Two-Component Regulatory System in Pseudomonas aeruginosa
Membrane impermeability is the major contributing factor to multidrug resistance in clinical isolates of Pseudomonas aeruginosa. By using laboratory strain PAK, a spontaneous P. aeruginosa mutant (mutant PAK1-3) whose membrane had reduced permeability and which displayed increased levels of resistance to various antibiotics, especially aminoglycosides, was i
American Society for Microbiology.
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3. Lipopolysaccharide changes in impermeability-type aminoglycoside resistance in Pseudomonas aeruginosa.
Clinical isolates of Pseudomonas aeruginosa were examined for the basis of impermeability-type aminoglycoside resistance. Two apparently related burn isolate strains with high-level (strain 8803) and low-level (strain 13934) gentamicin resistance each had a plasmid. Transformation of the plasmid from either strain to P. aeruginosa PAO503 resulted in low-leve
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4. Molecular dissection of the epsilon subunit of the chloroplast ATP synthase of spinach.
The gene encoding the epsilon subunit (atpE) of the chloroplast ATP synthase of Spinacia oleracea has been overexpressed in Escherichia coli. The recombinant protein can be solubilized in 8 M urea and directly diluted into buffer containing ethanol and glycerol to obtain epsilon that is as biologically active as epsilon purified from chloroplast-coupling fac
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5. Outer mitochondrial membrane permeability can regulate coupled respiration and cell survival
Coupled cellular respiration requires that ATP and ADP be efficiently exchanged between the cytosol and the mitochondrial matrix. When growth factors are withdrawn from dependent cells, metabolism is disrupted by a defect in ATP/ADP exchange across the mitochondrial membranes. Unexpectedly, we find that this defect results from loss of outer mitochondrial me
The National Academy of Sciences.
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6. Prevalence of outer membrane porin alteration in beta-lactam-antibiotic-resistant Enterobacter aerogenes.
We evaluated the prevalence of impermeability as a mechanism associated with resistance against beta-lactam antibiotics in members of the family Enterobacteriaceae. During a 1-year period, 80 strains were selected from 3,110 routinely isolated strains according to their noticeable cross-resistance pattern to cephalosporins. They were tested for (i) outer mem
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7. Electron Spin Resonance Studies of Spin-Labeled Mammalian Cells by Detection of Surface-Membrane Signals
Lipid-soluble spin labels were incorporated into human lymphocytes and mouse L-cells and the resulting electron spin resonance spectra were compared with spectra obtained from similarly labeled human erythrocytes. Spin labels were found in all subcellular fractions of the nucleated cells that contained membranes. Spinlabeled cells remained viable and capable
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8. Cloned diphtheria toxin within the periplasm of Escherichia coli causes lethal membrane damage at low pH.
Acidic pH within endosomal vesicles of sensitive animal cells triggers a conformational change in diphtheria toxin (DT) that is believed to cause the B chain to insert into the vesicular membrane and the enzymic A chain to be released into the cytosol. In artificial lipid bilayers, DT forms ion-conductive channels under mildly acidic conditions (pH approxima
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9. Effect of Polymyxin B on Antibiotic-Resistant Proteus mirabilis
The surface properties of polymyxin B-resistant Proteus mirabilis are markedly altered by the antibiotic. The effects include the development of susceptibility to surface-active agents such as deoxycholate or tris(hydroxymethyl)aminomethane and a marked increased osmotic fragility. However, cell wall impermeability to various agents such as erythromycin, act
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10. Effect of Temperature on Glycerol Retention in the Halotolerant Algae Dunaliella and Asteromonas
Algae of the genera Dunaliella and Asteromonas can maintain extremely high concentration gradients (>104) of glycerol between the intracellular space and the medium. This unique ability is highly temperature-dependent. Treating the algae for several minutes at temperatures exceeding 60 C causes complete release of all the internally held glycerol; 50% releas
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11. Functional expression of mouse Mdr1 in an outer membrane permeability mutant of Escherichia coli.
Functional expression of the multidrug resistance protein P-glycoprotein (P-gp) in Escherichia coli is providing an appropriate system for structure/function studies and might provide an invaluable tool to screen potential P-gp substrates and inhibitors. The major problem encountered in such studies, however, is the impermeability of the outer membrane of Gr
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12. Cyclic adenosine monophosphate-dependent kinase in cystic fibrosis tracheal epithelium.
Cl-impermeability in cystic fibrosis (CF) tracheal epithelium derives from a deficiency in the beta-adrenergic regulation of apical membrane Cl- channels. To test the possibility that cAMP-dependent kinase is the cause of this deficiency, we assayed this kinase in soluble fractions from cultured airway epithelial cells, including CF human tracheal epithelial