Biochemical characterization of a cefotaximehydrolysing &#946-lactamase encoded by a conjugative plasmid

During the nosocomials infections occurring in the intensive care unit of the military hospital of Tunis in 2005, the Enterobacter cloacae BW 1150 strain was isolated from a stool culture. This strain was found to have a high level resistance to broad-spectrum -lactams. Resistance profile against thevarious families of antibiotics was determined using the disc diffusion test. The minimal inhibitory concentrations values showed that this strain was resistant to the -lactams such as ampicillin and the extended spectrum cephalosporins (cefotaxime, ceftriaxon and cefpirome). Analysis of this strain by the disk diffusion test revealed synergies between amoxicillin-clavulanate (AMX-CA) and ceftriaxon, ceftazidime and cefotaxime. Cell sonicate of this isolate is very active against cefotaxime and showed aspecific activity (AS) of 7.54 U/mg for the same antibiotic. This activity was inhibited by the sulbactam and the clavulanic acid. Isoelectrofocusing methods revealed that the crude extract of the E. cloacae BW 1150 strain showed 1 - lactamase activity with an isoelectric piont (pI) of about 8. This activity was transferred by conjugation and was highly expressed in the transconjugant

Comparaison de la composition physicochimique du lait camelin et bovin du Sud tunisien; variation du pH et de l’acidité à différentes températures

La composition physicochimique du lait de chamelle est variable selon l’alimentation des animaux, les conditions environnementales ainsi que la période de lactation. Dans le but de déterminer la composition du lait de chamelle du sud tunisien, le lait camelin de la région a été comparé à celui bovin sur le plan de l’acidité et du pH du lait des deux espèces en fonction de la température du milieu. Le lait de chamelle est plus acide (17,25 ± 1,035°D) et moins dense (d= 1,027± 0,003) que le lait de vache. Le lait de vache est plus riche en matière protéique (34,15 ± 3,11 g/L), matière sèche (119,43 ± 15,34g/L) et azote non protéique NPN (1,04 ± 0,08g/L). Le suivi de la variation du pH et de l’acidité du lait camelin et bovin à trois températures différentes (température ambiante (25°C), à 4°C et à -4°C) a révélé une acidification plus lente du lait de chamelle dans les trois cas avec une conservation durant 30 heures à température ambiante, 7 jours dans le réfrigérateur (4°C) alors quelle est de 5 jours pour le lait de vache à la même température. La congélation du lait à -4°C peut ainsi constituer une méthode simple pour la conservation du lait camelin qui n’est accessible que dans les régions de sa production.Mots-clés : Lait, chamelle, vache, composition physicochimique, acidité,températur

Évaluation des niveaux d’exposition et des effets sur la santé des travailleurs exposés aux poussières de bois dans la région de Sidi-Bel-Abbès en Algérie

ObjectifL’objectif de notre enquête est d’évaluer les risques et les niveaux d’exposition aux poussières de bois inhalables chez les travailleurs du bois. Méthode Une enquête descriptive de type transversal a été menée sur une période de sept mois allant de novembre 2007 à mai 2008, auprès des 100 menuiseries recensées au niveau de la wilaya de Sidi-Bel-Abbès. Seulement 87 entreprises ont répondu positivement à notre enquête, dont l’effectif total est de 620 menuisiers. La population étudiée est constituée de 400 artisans menuisiers, exclusivement de sexe masculin répondant au critère majeur d’inclusion à savoir ayant plus de 70 % de leurs temps annuels de travail en atelier. Les menuisiers en pose seule ainsi que les apprentis ont été exclus de notre étude. Un questionnaire médical pour chaque salarié et un questionnaire technique au niveau de chaque entreprise ont été remplis par le même médecin du travail chargé de l’enquête, cela nous a permis une meilleure connaissance des pratiques de ces salariés et d’établir un score d’exposition. La saisie et l’analyse des données ont été faites avec SPSS.11.5. Résultats Un risque collectif moyen a été évalué par le calcul des scores par entreprise. Les entreprises ont été classées en trois catégories de risque : fort–moyen–faible. L’âge moyen était de 39,11 ± 1,19 ans, l’ancienneté moyenne au poste est de 17,75 ± 0,98 ans. Les fumeurs représentaient 33,3 % de notre population dont 38,34 % supérieurs à 10 PA et avec 55 % des menuisiers qui travaillaient le bois dur. Les aspirations sur machines fixes existaient seulement dans 28 % versus 3 % sur machines portatives et uniquement 27 % des travailleurs utilisaient des moyens de protection individuels. L’obstruction nasale restait le signe le plus rapporté à 59 %. Conclusion Les scores laissent prévoir un empoussièrement excessif. Les signes irritatifs et allergiques sur le tractus des voies aériennes supérieures ont été observés. Axant nos priorités sur la prévention et la sensibilisation des menuisiers

Efficient dynamical nuclear polarization in quantum dots: Temperature dependence

We investigate in micro-photoluminescence experiments the dynamical nuclear polarization in individual InGaAs quantum dots. Experiments carried out in an applied magnetic field of 2T show that the nuclear polarization achieved through the optical pumping of electron spins is increasing with the sample temperature between 2K and 55K, reaching a maximum of about 50%. Analysing the dependence of the Overhauser shift on the spin polarization of the optically injected electron as a function of temperature enables us to identify the main reasons for this increase.Comment: 5 pages, 3 figure

High-level cefotaxime-resistant Proteus mirabilis strain isolated from a Tunisian intensive care unit ward: CTX-M-8 extended-spectrum β-lactamase coproduced with a plasmid mediated AmpC lactamase

The aimed of this study was to determine the implication of the biochemical and the molecular mechanism and to describe the properties of an extended-spectrum β-lactamase (ESBL) CTX-M-8 which was reported for the first time in Africa. A clinical isolate of Proteus mirabilis FS6449 was isolated from a patient hospitalized at an intensive care unit of the Military Hospital in Tunisia in 2009. Antimicrobial susceptibility was determined with the disk diffusion method according to Clinical and Laboratory Standards Institute (CLSI) guidelines and revealed that this strain was resistant to expanded-spectrum β-lactams. Analysis of P. mirabilis FS6449 by double-disk synergy test yielded a positive result suggesting the production of ESBLs. Sonicate of the isolate hydrolysed cefotaxime and benzylpenicillin. Isoelectric focusing exhibited four β-lactamase bands of isoelectric points (pIs) 5.6, 6, 6.5 and over 7.6. Polymerase chain reaction (PCR) and sequencing experiments revealed the presence of four β-lactamase genes encoding TEM-2, CTX-M-8, TEM-24, and an AmpC enzyme. Among them, the genes encoding TEM-24 and an AmpC enzyme were transferred to the recipient by conjugation experiments.Keywords: Resistance, β-lactamase, Proteus mirabilisAfrican Journal of Biotechnology Vol. 12(21), pp. 3278-328

Efficient Delivery of Hydrophilic Small Molecules to Retinal Cell Lines Using Gel Core-Containing Solid Lipid Nanoparticles

In this study, we developed a novel solid lipid nanoparticle (SLN) formulation for drug delivery of small hydrophilic cargos to the retina. The new formulation, based on a gel core and composite shell, allowed up to two-fold increase in the encapsulation efficiency. The type of hydrophobic polyester used in the composite shell mixture affected the particle surface charge, colloidal stability, and cell internalization profile. We validated SLNs as a drug delivery system by performing the encapsulation of a hydrophilic neuroprotective cyclic guanosine monophosphate analog, previously demonstrated to hold retinoprotective properties, and the best formulation resulted in particles with a size of ±250 nm, anionic charge > −20 mV, and an encapsulation efficiency of ±60%, criteria that are suitable for retinal delivery. In vitro studies using the ARPE-19 and 661W retinal cell lines revealed the relatively low toxicity of SLNs, even when a high particle concentration was used. More importantly, SLN could be taken up by the cells and the release of the hydrophilic cargo in the cytoplasm was visually demonstrated. These findings suggest that the newly developed SLN with a gel core and composite polymer/lipid shell holds all the characteristics suitable for the drug delivery of small hydrophilic active molecules into retinal cells

magma and volatile supply to post collapse volcanism and block resurgence in siwi caldera tanna island vanuatu arc

V24C-04. Allen, S. R. (2005). Complex spatterand pumice-rich pyroclastic deposits from an andesitic caldera forming eruption: The Siwi pyroclastic sequence, Tanna, Vanuatu. Bulletin of Volcanology 67

Utilization of prickly pear waste for baker's yeast production

The feasibility of baker's yeast production using fruits and peels of Opuntia ficus indica (OFI) as carbohydrate feedstock was investigated. Two response surface methodologies involving central composite face centered design (CCFD) were successfully applied. The effects of four independent variables on baker's yeast production from OFI fruit juice was evaluated using the first CCFD. The best results were obtained with 24 H of inoculum age, 30 degrees C temperature, 200 rpm of agitation, and 10% inoculum size. At the maximum point, the biomass concentration reached 9.29 g/L. A second CCFD was performed to optimize the sugar extraction from OFI fruit peels. The potential of these latter as a fermentation substrate was determined. From the experimental results, the OFI fruit peel is an appropriate carbon source for the production of baker's yeast. The maximum biomass concentration was 12.51 g/L. Different nitrogen supplements were added to promote the yields of baker's yeast. Corn steep liquor was found to be the best alternative nutrient source of casein hydrolysate and yeast extract for baker's yeast production.info:eu-repo/semantics/publishedVersio

Modelling and parametric study of the re-anchorage of ruptured tendons in bonded post-tensioned concrete

The contribution of ruptured tendons to the residual strength of bonded post-tensioned concrete structures is currently assessed based on pre-tensioned concrete bond models. However, this approach is inaccurate due to the inherent differences between pre-tensioned and post-tensioned concrete. In this paper, a non-linear 3D finite element model is developed for the re-anchoring of a ruptured tendon in post-tensioned concrete. The model is validated using full-field displacement measurement from 33 post-tensioned concrete prisms and previous experimental data on beams from the literature. The influence of different parameters was investigated, including tendon properties (i.e. diameter, roughness), duct properties (i.e. diameter, thickness, material), initial prestress, concrete strength, grout strength, grout voids, stirrups, and strands, on the tendon re-anchorage. The most influential parameters are found to be tendon and duct properties

Human Cellular Immune Response to the Saliva of Phlebotomus papatasi Is Mediated by IL-10-Producing CD8+ T Cells and Th1-Polarized CD4+ Lymphocytes

Cutaneous leishmaniasis affects millions of people worldwide and is caused by protozoa of the genus Leishmania. The parasite is transmitted during sand fly bites. While probing the skin for a blood meal, vectors salivate into the host's skin. Sand fly saliva contains several components that increase hemorrhage and interfere with the host's inflammatory response. Data obtained in mice originally indicate that immunization against saliva protected from leishmaniasis supporting possibility that leishmaniasis could be prevented by a vaccine based on sand fly saliva. Herein we investigated the nature and the importance of the cellular immune response developed against sand fly saliva by individuals at risk of cutaneous leishmaniasis due to Leishmania major. We demonstrated that the immunity against saliva is dominated by the activation of lymphocytes producing a suppressive cytokine called IL-10. These data may preclude the protective effect of sand fly saliva pre-exposure in humans. Further experiments revealed that the production of IL-10 masked the presence of a second kind of lymphocytes producing IFN-γ, a rather protective cytokine. The latter finding highlights the importance of the identification of the proteins activating the latter lymphocytes in order to develop vaccines based on selected proteins from the saliva of sand flies