215 research outputs found
Impact du diabète sur le travail et usage des antidiabétiques oraux chez les travailleurs au Québec
Ce mémoire a deux volets. L'objectif du premier était d'évaluer l'impact du diabète de type 2 sur la productivité au travail. Les objectifs du deuxième étaient de décrire la persistance et l'observance aux traitements antidiabétiques et de déterminer les facteurs y étant associés chez des travailleurs atteints de diabète de type 2. Au premier volet, nous avons effectué une synthèse systématique des connaissances. Au deuxième, nous avons réalisé une étude de cohorte à l'aide des données administratives de la Régie de l'assurance maladie du Québec. Selon notre synthèse, le diabète a un impact négatif significatif sur la productivité au travail. Parmi les 41006 sujets de la cohorte, 81,1% prenaient leur traitement un an après son début et de ceux-ci 69,7% avaient eu en leur possession des médicaments antidiabétiques pendant au moins 80% des jours de cette première année. La persistance et l'observance aux traitements antidiabétiques sont affectées par plusieurs déterminants
Innovative Overheating solution for solar thermal collector using a reflective surface included in the air gap
In this work, a new solution to prevent the overheating of solar collectors in the case of stagnation is presented. The solution proposed consists of inserting a reflective sheet inside the solar collector between the absorber and the glass cover to reduce the incoming energy by reflecting solar radiation. This protection is switched ON or OFF according to the absorber temperature. A prototype has been manufactured and tested in outside conditions and in laboratory. A numerical model of the solar collector with the protection was developed and has been validated. The calculated temperature values are very close to the measured data. The experimental and numerical results showed the good behaviour of the proposed solution
APD2: the updated antimicrobial peptide database and its application in peptide design
The antimicrobial peptide database (APD, http://aps.unmc.edu/AP/main.php) has been updated and expanded. It now hosts 1228 entries with 65 anticancer, 76 antiviral (53 anti-HIV), 327 antifungal and 944 antibacterial peptides. The second version of our database (APD2) allows users to search peptide families (e.g. bacteriocins, cyclotides, or defensins), peptide sources (e.g. fish, frogs or chicken), post-translationally modified peptides (e.g. amidation, oxidation, lipidation, glycosylation or d-amino acids), and peptide binding targets (e.g. membranes, proteins, DNA/RNA, LPS or sugars). Statistical analyses reveal that the frequently used amino acid residues (>10%) are Ala and Gly in bacterial peptides, Cys and Gly in plant peptides, Ala, Gly and Lys in insect peptides, and Leu, Ala, Gly and Lys in amphibian peptides. Using frequently occurring residues, we demonstrate database-aided peptide design in different ways. Among the three peptides designed, GLK-19 showed a higher activity against Escherichia coli than human LL-37
Plant defence peptides
Eight families of antimicrobial peptides, ranging in size from 2 to 9 kD, have been identified in plants. These are thionins, defcnsins, so-called lipid iransfer proteins, hevein- and knottin-Iike peptides, MBPJ, lb AMP, and the recently reported snakins. All of them have compact structures that are stabilized by 2-6 disulfide bridges. They are part of both permanent and inducible defense barriers. Transgenic overe.xpression of the corresponding genes leads to enhanced tolerance to pathogens, and peptide-sensitive pathogen mutants have reduced virulence
Substrate specificity of a peptidyl-aminoacyl-l/d-isomerase from frog skin
In the skin of fire-bellied toads (Bombina species), an aminoacyl-l/d-isomerase activity is present which catalyses the post-translational isomerization of the l- to the d-form of the second residue of its substrate peptides. Previously, this new type of enzyme was studied in some detail and genes potentially coding for similar polypeptides were found to exist in several vertebrate species including man. Here, we present our studies to the substrate specificity of this isomerase using fluorescence-labeled variants of the natural substrate bombinin H with different amino acids at positions 1, 2 or 3. Surprisingly, this enzyme has a rather low selectivity for residues at position 2 where the change of chirality at the alpha-carbon takes place. In contrast, a hydrophobic amino acid at position 1 and a small one at position 3 of the substrate are essential. Interestingly, some peptides containing a Phe at position 3 also were substrates. Furthermore, we investigated the role of the amino-terminus for substrate recognition. In view of the rather broad specificity of the frog isomerase, we made a databank search for potential substrates of such an enzyme. Indeed, numerous peptides of amphibia and mammals were found which fulfill the requirements determined in this study. Expression of isomerases with similar characteristics in other species can therefore be expected to catalyze the formation of peptides containing d-amino acids
Identification and characterization of antibacterial compound(s) of cockroaches (Periplaneta americana)
Infectious diseases remain a significant threat to human health, contributing to more than 17 million deaths, annually. With the worsening trends of drug resistance, there is a need for newer and more powerful antimicrobial agents. We hypothesized that animals living in polluted environments are potential source of antimicrobials. Under polluted milieus, organisms such as cockroaches encounter different types of microbes, including superbugs. Such creatures survive the onslaught of superbugs and are able to ward off disease by producing antimicrobial substances. Here, we characterized antibacterial properties in extracts of various body organs of cockroaches (Periplaneta americana) and showed potent antibacterial activity in crude brain extract against methicillin-resistant Staphylococcus aureus and neuropathogenic E. coli K1. The size-exclusion spin columns revealed that the active compound(s) are less than 10 kDa in molecular mass. Using cytotoxicity assays, it was observed that pre-treatment of bacteria with lysates inhibited bacteria-mediated host cell cytotoxicity. Using spectra obtained with LC-MS on Agilent 1290 infinity liquid chromatograph, coupled with an Agilent 6460 triple quadruple mass spectrometer, tissues lysates were analyzed. Among hundreds of compounds, only a few homologous compounds were identified that contained isoquinoline group, chromene derivatives, thiazine groups, imidazoles, pyrrole containing analogs, sulfonamides, furanones, flavanones, and known to possess broad-spectrum antimicrobial properties, and possess anti-inflammatory, anti-tumour, and analgesic properties. Further identification, characterization and functional studies using individual compounds can act as a breakthrough in developing novel therapeutics against various pathogens including superbugs
Ketamine for perioperative pain management in children: a meta-analysis of published studies
Peptides thérapeutiques à fleur de peau de grenouille
La recherche de nouvelles molécules bioactives utilisables en thérapeutique est un enjeu
majeur de santé publique, en particulier dans le traitement de certaines maladies comme le
cancer. Dans cette optique, l’exploration du venin des animaux (serpents, amphibiens,
cônes, scorpions, insectes...), qui produisent des molécules de structures et d’activités
biologiques diverses, est une piste très prometteuse. La recherche dans ce domaine a
conduit à la découverte de neuropeptides, d’hormones, de toxines, de peptides
antimicrobiens et d’autres médiateurs extrêmement puissants. Ceux-ci sont maintenant
utilisés dans de nombreux domaines aussi bien en recherche fondamentale pour la
compréhension des mécanismes biochimiques et physiologiques, qu’en recherche
translationnelle comme outil de diagnostic médical ou à des fins thérapeutiques. Le Pr. V.
Erspamer est le premier à avoir montré, dès les années 1930, qu’en plus des amines
biogènes et des alcaloïdes, les glandes granulaires de la peau des amphibiens produisaient
également d’énormes quantités de peptides de structures et d’activités biologiques
diverses. Il a montré aussi que ces peptides se retrouvaient, le plus souvent, sous forme
de peptides identiques ou similaires dans le système nerveux central et le tractus
gastro-intestinal des mammifères. Ces observations sont résumées sous forme d’un concept
de triangle « peau-cerveau-intestin » qui stipule que tout peptide trouvé dans un
compartiment devrait se retrouver dans les deux autres. De plus, l’abondance, la facilité
d’extraction et d’identification des peptides de la peau des amphibiens font de ce modèle
un moyen pour la recherche de leurs équivalents chez les mammifères où ils sont présents
en quantités infimes. Cette approche présente deux avantages : (i) au plan fondamental, la
grande diversité peptidique, l’ubiquité et la multiplicité des fonctions auxquelles ils
participent constituent une véritable chimiothèque pour comprendre les mécanismes
fondamentaux de reconnaissance et de transduction des signaux et étudier les bases
physico-chimiques de leur spécificit;é (ii) au plan des applications, la relative
simplicité de ces molécules et l’essor des techniques de production massive par synthèse
chimique ou par recombinaison offrent un potentiel novateur pour le développement d’agents
à visée pharmacologique ou thérapeutique
Dermenkephalin and deltorphin I reveal similarities within ligand-binding domains of μ- and δ-opioid receptors and an additional address subsite on the δ-receptor
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