Search results for "Porins"
showing 10 items of 79 documents
Ceftolozane Pharmacokinetics in a Septic Critically Ill Patient under Different Extracorporeal Replacement Therapies
2019
Ceftolozane-tazobactam (C/T), a novel fifth-generation cephalosporin/β-lactamase inhibitor combination active against multidrug-resistant (MDR) Pseudomonas aeruginosa, is currently approved by the U.S. Food and Drug Administration (FDA) to treat complicated intra-abdominal and urinary tract
Fatal multi-organ failure following anaphylactic shock induced by ceftriaxone
2014
In the latest years, based on the wide use of cephalosporins for antibiotic therapy, a large interest focused on the identification of causal relationship of adverse reactions after their prescription. We report a case of fatal anaphylactic shock following the administration of ceftriaxone in a woman who had tolerated the previous exposure to the drug. This case adds a contribution to the few cases reported in literature to further suggest the possibility of severe anaphylaxis after the administration of ceftriaxone even in patients without any previous reaction to this drug.
Anionic Lipids Modulate the Activity of the Aquaglyceroporin GlpF
2015
AbstractThe structure and composition of a biological membrane can severely influence the activity of membrane-embedded proteins. Here, we show that the E. coli aquaglyceroporin GlpF has only little activity in lipid bilayers formed from native E. coli lipids. Thus, at first glance, GlpF appears to not be optimized for its natural membrane environment. In fact, we found that GlpF activity was severely affected by negatively charged lipids regardless of the exact chemical nature of the lipid headgroup, whereas GlpF was not sensitive to changes in the lateral membrane pressure. These observations illustrate a potential mechanism by which the activity of an α-helical membrane protein is modula…
Genome analysis of enterobacteriaceae with non-wild type susceptibility to third-generation cephalosporins recovered from diseased dogs and cats in E…
2020
Extended-spectrum-β-lactamases (ESBL) and plasmid-mediated cephalosporinases (pAmpC)-producing Enterobacteriaceae isolates are now reported worldwide in humans, animals, and in the environment. We identified the determinants of resistance to β-lactams and associated resistance genes as well as phylogenetic diversity of 53 ESBL- or pAmpC-producing Enterobacteriaceae isolated from dogs and cats in Europe.Of a collection of 842 Enterobacteriaceae isolates that were recovered in 2013 and 2014 from 842 diseased and untreated dogs and cats, for 242 ampicillin or amoxicillin resistant isolates (MIC ≥ 16 mg/L), cefotaxime (CTX) and ceftazidime (CAZ) MICs were determined. Isolates with CTX and/or CA…
Components of an antigen-/T cell receptor-independent pathway of lymphokine production
1991
The general way to induce the synthesis of lymphokines by T cells is the stimulation through the T cell receptor (TcR) complex which results in an increase of intracellular [Ca2+] and in the activation of a tyrosine kinase as well as of protein kinase C. Lymphokine production induced via the TcR is inhibited by the immunosuppressive drug cyclosporin A (CsA). However, an alternative pathway of lymphokine production exists. Several T lymphocyte clones can synthesize interferon-gamma (IFN-gamma), granulocyte-monocyte colony-stimulating factor, and small amounts of interleukin (IL3) when stimulated with syngeneic or allogeneic accessory cells (AC) plus IL2. In contrast to the TcR pathway the al…
Divalent Cations Reduce the pH Sensitivity of OmpF Channel Inducing the PKA Shift of Key Acidic Residues
2011
In contrast to the highly-selective channels of neurophysiology employing mostly the exclusion mechanism, different factors account for the selectivity of large channels. Elucidation of these factors is essential for understanding the permeation mechanisms in ion channels and their regulation in vivo. The interaction between divalent cations and a protein channel, the bacterial porin OmpF, has been investigated paying attention to the channel selectivity and its dependence on the solution pH. Unlike the experiments performed in salts of monovalent cations, the channel is now practically insensitive to pH, being anion selective all over the pH range considered. Electrostatic calculations bas…
Amperometric detection of extended-spectrum β-lactamase activity : application to the characterization of resistant E.coli strains
2015
EA MERS CT3; International audience; The amperometric detection of extended-spectrum β-lactamase (ESBL) with carbon screen-printed sensors was investigated in the presence of the Nitrocefin, a commercially-available β-lactamase chromogenic cephalosporin substrate. Using an ESBL isolated from a clinical sample, it was shown for the first time that the intensity of a specific anodic pic current (EP = [similar]+0.3 V vs. Ag/AgCl) resulting from the catalytic hydrolysis of the β-lactam ring was proportional to the amount of ESBL. The proof-of-principle of a novel susceptibility assay for the rapid and accurate identification of ESBL- producing bacteria was then demonstrated. The detection schem…
Susceptibility of Pseudomonas aeruginosa isolates to ceftazidime is unrelated to the expression of the outer membrane protein OprC.
1997
Previously, it has been postulated that the porin OprC facilitates the diffusion of ceftazidime through the outer membrane of Pseudomonas aeruginosa. To further investigate this claim, the outer membrane protein (OMP) profiles of 22 ceftazidime-susceptible clinical isolates were analyzed. No correlation was found between MIC values and the level of expression of OprC. Further, OprC was either undetectable or expressed in reduced amounts in 12 isolates. In contrast, OprF and OprE were present in all isolates studied. This study suggests that OprC is dispensable for the permeation of ceftazidime through the outer membrane of P. aeruginosa.
Differentiation of herpes simplex virus-induced fusion from without and fusion from within by cyclosporin A and compound 48/80.
1991
Treating strains of herpes simplex virus (HSV) in culture with either cyclosporin A or compound 48/80, allowed the strains to be divided into two groups. Group 1 contains the strains ANG and HFEM of HSV-1 and Lux syn (HSV-2) producing fusion from within (FFWI) and fusion from without (FFWO). Cyclosporin A fails to inhibit both types of fusion at concentrations up to 100 microM. Strains ANG and HFEM belong to the syn 3 marker locus group identified for HSV-1. Group 2 contains all other fusion-producing strains of HSV tested so far. Cyclosporin A inhibits FFWI at concentrations as low as 10 to 20 microM. These strains belong to the syn locus marker groups 1, 2, 4 and 5. From the fact that mut…
A pH-tunable nanofluidic diode: electrochemical rectification in a reconstituted single ion channel.
2006
We report pH-dependent electrochemical rectification in a protein ion channel (the bacterial porin OmpF) reconstituted on a planar phospholipid membrane. The measurements performed at single-channel level show that the electric current is controlled by the protein fixed charge and it can be tuned by adjusting the local pH. Under highly asymmetric pH conditions, the channel behaves like a liquid diode. Unlike other nanofluidic devices that display also asymmetric conductance, here the microscopic charge distribution of the system can be explored by using the available high-resolution (2.4 A) channel crystallographic structure. Continuum electrostatics calculations confirm the hypothesized bi…