80 research outputs found
Lipid A structure and immunoinhibitory effect of the marine bacterium Cobetia pacifica KMM 3879T
No full textThe structural elucidation of lipopolysaccharides (LPSs) from Gram‐negative marine bacteria, along with the assessment of their immunological properties, is a fascinating and active research field. Such studies can aid understanding of adaptation phenomena that occur in the marine environment, but they can also open up new perspectives on the design and development of new immunoregulatory drugs. In this paper, we report the structural characterization of the lipid A component of the LPS isolated from the marine bacterium Cobetia pacifica KMM 3879T, which is characterized by a family of structures differing in their acylation patterns. The structural assignment was achieved through extensive chemical analysis and matrix‐assisted laser desorption/ionization (MALDI) mass spectrometry. Moreover, cellular immunology studies on the LPS highlighted its low immunostimulatory impact, as well as a very interesting and promising inhibitory activity of the toxic effects of Escherichia coli LPS
A new regenerative-based algorithm for closed Jackson networks - by Amal Sami Abou Nehme Sawaya
No full textProjects (M.E.M.) -- Engineering Management Program, A.U.B. -- Includes abstract -- References: leaf 6
Women as CEO's prospects in Lebanon - by Leila Sami Abou Nehme Sawaya
No full textProject (M.B.A.)Bibliography : leaves 68-7
Workforce diversity and adaptability - by Sarah Sami Obeid
No full textThesis (M.A.)--American University of Beirut, Department of Political Studies and Public Administration, 2002;"Advisor: Dr. Michel Nehme,Associate Professor, Political Studies and Public Administration--Member of Committee: Dr. Randa Antoun, Lecturer, PolBibliography : leaves 89-90.Workforce diversity refers to the varied background of employees in terms of race, color, gender, education, social class, and mental and physical capabilities. The management of a diverse workforce has increased in recent years and has been an issue of
Minor modifications to the phosphate groups and the C3' acyl chain length of lipid A in two Bordetella pertussis strains, BP338 and 18-323, independently affect toll-like receptor 4 protein activation
No full textInternational audienceLipopolysaccharides (LPS) of Bordetella pertussis are important modulators of the immune system. Interaction of the lipid A region of LPS with the Toll-like receptor 4 (TLR4) complex causes dimerization of TLR4 and activation of downstream nuclear factor κB (NFκB), which can lead to inflammation. We have previously shown that two strains of B. pertussis, BP338 (a Tohama I-derivative) and 18-323, display two differences in lipid A structure. 1) BP338 can modify the 1- and 4'-phosphates by the addition of glucosamine (GlcN), whereas 18-323 cannot, and 2) the C3' acyl chain in BP338 is 14 carbons long, but only 10 or 12 carbons long in 18-323. In addition, BP338 lipid A can activate TLR4 to a greater extent than 18-323 lipid A. Here we set out to determine the genetic reasons for the differences in these lipid A structures and the contribution of each structural difference to the ability of lipid A to activate TLR4. We show that three genes of the lipid A GlcN modification (Lgm) locus, lgmA, lgmB, and lgmC (previously locus tags BP0399-BP0397), are required for GlcN modification and a single amino acid difference in LpxA is responsible for the difference in C3' acyl chain length. Furthermore, by introducing lipid A-modifying genes into 18-323 to generate isogenic strains with varying penta-acyl lipid A structures, we determined that both modifications increase TLR4 activation, although the GlcN modification plays a dominant role. These results shed light on how TLR4 may interact with penta-acyl lipid A species
Comparison of lipopolysaccharide structures of Bordetella pertussis clinical isolates from pre- and post-vaccine era
No full textEndotoxins are lipopolysaccharides (LPS), and major constituents of the outer membrane of Gram-negative bacteria. Bordetella pertussis LPS were the only major antigens, of this agent of whooping-cough, that were not yet analyzed on isolates from the pre- and post-vaccination era. We compared here the LPS structures of four clinical isolates with that of the vaccine strain BP 1414. All physico-chemical analyses, including SDS-PAGE, TLC, and different MALDI mass spectrometry approaches were convergent. They helped demonstrating that, on the contrary to some other B. pertussis major antigens, no modification occurred in the dodecasaccharide core structure, as well as in the whole LPS molecules. These results are rendering these major antigens good potential vaccine components. Molecular modeling of this conserved LPS structure also confirmed the conclusions of previous experiments leading to the production of anti-LPS monoclonal antibodies and defining the main epitopes of these major antigens. \ua9 2013 Elsevier Ltd.Peer reviewed: YesNRC publication: Ye
Predictive value of cardiac troponin T and I in hemodialysis patients
No full textCardiac troponin T (cTnT) and I (cTnI) levels are considered as important diagnostic tools in acute coronary events. They could be of predictive value in hemodialysis (HD) patients. The aim of this study was to determine the prevalence of increased cTnI and cTnT in HD patients and their prognostic relevance to all-cause mortality. We measured cTnT and cTnI at baseline in 145 asymptomatic HD patients. We used three different cut-off criteria to define elevated cardiac troponin levels as follows: the 99 th percentile of a reference population, the lowest concentration to give a 10% imprecision [10% coefficient of variation (10% CV)] and the relative operating characteristic (ROC) curve-determined value optimized for diagnostic sensitivity and specificity for detection of myocardial injury (MI). These concentrations were 0.01 ng/mL, 0.03 ng/mL and 0.1 ng/mL for cTnT and 0.2 ng/mL, 0.6 ng/mL and 1 ng/mL for cTnI, respectively. Patients were followed for all-cause mortality (median follow-up 551 days). Kaplan-Meier survival curves, log-rank test and Cox models were employed to determine whether baseline cTnT and cTnI levels were predictive of mortality. Greater percentages of patients had an increased cTnT versus cTnI at each cut-off as follows: 99 th percentile, 90.3% versus 35.2%; 10% CV, 73.1% versus 2.1%; and ROC, 20.7% versus 0.7%. During follow-up, 40 patients died. Elevated cTnT levels above the ROC concentration were associated with increased mortality, although it was not significant after adjustment for other risk factors. Univariate and adjusted hazard ratios were 2.3 [confidence intervals (CI), 1.2-4.5; P = 0. 01] and 1.9 (CI, 0.9-3.9; P = 0.07). No differences were found for cTnI levels. Diabetes mellitus was also an independent predictor of mortality. There is a high prevalence of positive cTnT and cTnI in asymptomatic HD patients, with a greater number of patients having an increased cTnT. Elevated troponin T, but not cTnI, seems to be associated with poor prognosis
The LipidA from Rhodopseudomonas palustris Strain BisA53 LPS Possesses a Unique Structure and Low Immunostimulant Properties
No full textThe search for novel lipid A analogues from any biological source that can act as antagonists, displaying inhibitory activity towards the production of pro-inflammatory cytokines, or as immunomodulators in mammals, is a very topical issue. To this aim, the structure and immunological properties of the lipopolysaccharide lipid A from the purple nonsulfur bacterium Rhodopseudomonas palustris strain BisA53 have been determined. This lipid A displays a unique structural feature, with a non-phosphorylated skeleton made up of the tetrasaccharide Manp-α-(1→4)-GlcpN3N-β-1→6-GlcpN3N-α-(1→1)-α-GalpA, and four primary amide-linked 14:0(3-OH) and, as secondary O-acyl substituents, a 16:0 and the very long-chain fatty acid 26:0(25-OAc), appended on the GlcpN3N units. This lipid A architecture is definitely rare, so far identified only in the genus Bradyrhizobium. Immunological tests on both murine bone-marrow-derived and human monocyte-derived macrophages revealed an extremely low immunostimulant capability of this LPS lipid A
Gut Microbiota Ecology and Inferred Functions in Children With ASD Compared to Neurotypical Subjects
No full textAutism spectrum disorders (ASDs) is a multifactorial neurodevelopmental disorder. The communication between the gastrointestinal (GI) tract and the central nervous system seems driven by gut microbiota (GM). Herein, we provide GM profiling, considering GI functional symptoms, neurological impairment, and dietary habits. Forty-one and 35 fecal samples collected from ASD and neurotypical children (CTRLs), respectively, (age range, 3-15 years) were analyzed by 16S targeted-metagenomics (the V3-V4 region) and inflammation and permeability markers (i.e., sIgA, zonulin lysozyme), and then correlated with subjects' metadata. Our ASD cohort was characterized as follows: 30/41 (73%) with GI functional symptoms; 24/41 (58%) picky eaters (PEs), with one or more dietary needs, including 10/41 (24%) with food selectivity (FS); 36/41 (88%) presenting high and medium autism severity symptoms (HMASSs). Among the cohort with GI symptoms, 28/30 (93%) showed HMASSs, 17/30 (57%) were picky eaters and only 8/30 (27%) with food selectivity. The remaining 11/41 (27%) ASDs without GI symptoms that were characterized by HMASS for 8/11 (72%) and 7/11 (63%) were picky eaters. GM ecology was investigated for the overall ASD cohort versus CTRLs; ASDs with GI and without GI, respectively, versus CTRLs; ASD with GI versus ASD without GI; ASDs with HMASS versus low ASSs; PEs versus no-PEs; and FS versus absence of FS. In particular, the GM of ASDs, compared to CTRLs, was characterized by the increase of Proteobacteria, Bacteroidetes, Rikenellaceae, Pasteurellaceae, Klebsiella, Bacteroides, Roseburia, Lactobacillus, Prevotella, Sutterella, Staphylococcus, and Haemophilus. Moreover, Sutterella, Roseburia and Fusobacterium were associated to ASD with GI symptoms compared to CTRLs. Interestingly, ASD with GI symptoms showed higher value of zonulin and lower levels of lysozyme, which were also characterized by differentially expressed predicted functional pathways. Multiple machine learning models classified correctly 80% overall ASDs, compared with CTRLs, based on Bacteroides, Lactobacillus, Prevotella, Staphylococcus, Sutterella, and Haemophilus features. In conclusion, in our patient cohort, regardless of the evaluation of many factors potentially modulating the GM profile, the major phenotypic determinant affecting the GM was represented by GI hallmarks and patients' age
Complete Bordetella avium, Bordetella hinzii and Bordetella trematum lipid A structures and genomic sequence analyses of the loci involved in their modifications∗
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