Intérêt de la chromatographie liquide d'interactions hydrophiles pour l'analyse de composés polaires dans des matrices complexes

Peer reviewe

Outcome of alimentary tract duplications operated on by minimally invasive surgery: a retrospective multicenter study by the GECI (Groupe d'Etude en Coeliochirurgie Infantile).

BACKGROUND: Alimentary tract duplications (ATD) are a rare cause of intestinal obstruction in childhood. There are many case reports but few series about laparoscopy or thoracoscopy for ATD. The aim of our study was to report the outcome of minimally invasive surgery (MIS) for ATD. METHODS: This was a retrospective multicenter study from the GECI (Groupe d\u27Etude en Coeliochirurgie Infantile). We reviewed the charts of 114 patients operated on by MIS for ATD from 1994 to 2009. RESULTS: Sixty-two patients (54 %) had a prenatal diagnosis. Forty-nine patients (43 %) were symptomatic before surgery: 33 of those patients (63 %) with postnatal diagnosis compared to 16 (25 %) with prenatal diagnosis (P < 0.01). In this last group, the median age at onset of symptoms was 16 days (range = 0-972). One hundred and two patients had laparoscopy (esophageal to rectal duplications) and 12 patients had thoracoscopy for esophageal duplications. The mean operative time was 90 min (range = 82-98). There were 32 (28 %) resection anastomoses, 55 (48 %) enucleations, and 27 (24 %) unroofings. The conversion rate was 32 %, and in a multivariate analysis, it was significantly higher, up to 41 % for patients weighing <10 kg (P < 0.01). Ten patients (8 %) had unintentional perioperative opening of the digestive tract during the dissection. Eight patients had nine postoperative complications, including six small bowel obstructions. The median length of hospital stay was 4 days (range = 1-21) without conversion and 6 days (range = 1-27) with conversion (P = 0.01). The median follow-up was 3 months (range = 1-120). Eighteen of the 27 patients who underwent partial surgery had an ultrasound examination during follow-up. Five (18 %) of them had macroscopic residue. CONCLUSION: This study showed that MIS for ATD is feasible with a low rate of complications. Patients with prenatal diagnosis should have prompt surgery to prevent symptoms, despite a high rate of conversion in small infants

Immobilized phenoloxidases in reactors for the oxidation of aquatic contaminants of emerging concern : toward a scalable industrial system

Laccase (EC 1.10.3.2), a biogenic catalyst of many oxidative reactions, has been previously identified to mitigate the risks to human health linked to the presence of phenolic contaminants at sub-nanomolar concentrations in water resources. Operational performance and cost-effectiveness of biocatalytic processes are key aspects for successful applications, although they have been overlooked in environmental biocatalysis. The thesis objectives were i) to delineate important features for the scalability of environmental biocatalytic processes, ii) to define a methodology for laccase insolubilization, iii) to decipher immobilized laccase activity and stability toward pollutant removal and iv) to assess the process economic viability. Multivariate analysis and modeling were effective in identifying Pareto-optimal formulation of laccase immobilized on mesoporous silica. High catalytic rates of immobilized laccase at low pollutant concentrations were obtained in a continuous flow packed-bed reactor given the observed reaction order. The reactor conversion rate increased in pollutant mixtures due to radical-mediated oxidations. Internal mass transfer limitations were found to control the conversion rate of weak acids but also to change inactivation kinetics in denaturing as well as operational conditions, conferring apparent stability to the biocatalysts. Although stable in wastewater, immobilized laccase was prone to a turnover- and substrate-dependent inactivation mechanism. Given the process performance, a laccase-based water treatment could be economically competitive in the industrial water market if fungal laccase price falls thanks to recent advances in heterologous laccase production.(AGRO - Sciences agronomiques et ingénierie biologique) -- UCL, 201

Formulation and characterization of an immobilized laccase biocatalyst and its application to eliminate organic micropollutants in wastewater

Over the past decades, water pollution by trace organic compounds (ngL-1) has become one of the key environmental issues for developed countries. To date there is no effective and sustainable remediation strategy available. Laccases from white rot fungi were found particularly attractive for the removal of some micropollutants such as the plasticizer bisphenol A (BPA), the anti-inflammatory drug diclofenac (DF) and the steroidal hormone 17-α-ethinylestradiol (EE2). Laccase immobilization is a prerequisite for their use in continuous water treatment processes. In this study, laccase from Coriolopsis gallica was immobilized on mesoporous silica spheres in a two-step adsorption-crosslinking process. The initial laccase activity, crosslinker (glutaraldehyde) concentration and extra protein (albumin) concentration were varied following a central composite experimental design and optimized with respect to the immobilization yield, activity and thermal stability of the biocatalysts. After a multi-objective optimization of the biocatalyst formulation, a maximum biocatalyst activity of 383Ug-1, determined with 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonate) at pH 4.5, was obtained. Biocatalyst particles were physically characterized by means of scanning electron microscopy, Brunauer-Emmett-Teller surface area and Barrett-Joyner-Halenda pore size analyses revealing few modifications of the surface area and structure during/after the immobilization procedure. The biocatalyst showed a significantly higher thermostability than the free enzyme with a half-life of 31.5hours and 3.9hours compared to 6.1hours and 0.6hours at 55°C and 75°C respectively. The biocatalyst was able to eliminate in a continuously stirred membrane reactor more than 95% of BPA 10μM and EE2 10μM and 70% of DF 10μM when treated individually and more than 90% when treated as a mixture in aqueous buffered solution (pH 5) for more than 60 reactor volumes. In real wastewater conditions (pH 7.8) the biocatalyst could degrade more than 85% of BPA and EE2 along with 30% of DF when tested in mixture for more than 80hours, which illustrates the potential of this biocatalyst for the treatment of aquatic micropollutants

Bio-inspired titania-based laccase biocatalyst for removal of EDCs

The removal of micropollutants from wastewater, especially endocrine disrupting chemicals (EDCs), is one of the recent challenges in environmental protection. EDCs can alter the normal function of the endocrine system of human and wildlife organisms causing adverse health effects in the organism or its progeny even at very low concentrations. Potential EDCs are used as additives or found as contaminants in common goods, in food, personal care products, cosmetics, plastics, textiles and construction materials. They are usually difficult to degrade due to their complex chemical structure and remain intact after chemical and biological processing in wastewater treatment plants. They have been detected in concentrations on the range of ng/L in rivers and secondary effluents all over the world. The MINOTAURUS project addresses these issues by the development of technologies based on immobilized enzymes and microorganisms able to degrade these recalcitrant micropollutants in wastewater, ground water and soil. The approach of our research group at the Université catholique de Louvain (UCL) is the use of immobilized laccases for the removal of EDCs in wastewater at environmentally relevant concentrations