Online monitoring and conditional regression tree test: Useful tools for a better understanding of combined sewer network behavior.

A good knowledge of the dynamic of pollutant concentration and flux in a combined sewer network is necessary when considering solutions to limit the pollutants discharged by combined sewer overflow (CSO) into receiving water during wet weather. Identification of the parameters that influence pollutant concentration and flux is important. Nevertheless, few studies have obtained satisfactory results for the identification of these parameters using statistical tools. Thus, this work uses a large database of rain events (116 over one year) obtained via continuous measurement of rainfall, discharge flow and chemical oxygen demand (COD) estimated using online turbidity for the identification of these parameters. We carried out a statistical study of the parameters influencing the maximum COD concentration, the discharge flow and the discharge COD flux. In this study a new test was used that has never been used in this field: the conditional regression tree test. We have demonstrated that the antecedent dry weather period, the rain event average intensity and the flow before the event are the three main factors influencing the maximum COD concentration during a rainfall event. Regarding the discharge flow, it is mainly influenced by the overall rainfall height but not by the maximum rainfall intensity. Finally, COD discharge flux is influenced by the discharge volume and the maximum COD concentration. Regression trees seem much more appropriate than common tests like PCA and PLS for this type of study as they take into account the thresholds and cumulative effects of various parameters as a function of the target variable. These results could help to improve sewer and CSO management in order to decrease the discharge of pollutants into receiving waters.

Spatial and temporal variations in otolith chemistry and relationships with water chemistry: a useful tool to distinguish Atlantic salmon Salmo salar parr from different natal streams.

Otolith elemental (Sr:Ca, Ba:Ca, Mn:Ca, Mg:Ca and Rb:Ca) and isotopic (87Sr:86Sr) profiles from several annual cohorts of juvenile Atlantic salmon Salmo salar were related to the physico-chemical characteristics (chemical signatures, flow rate, temperature and conductivity) of their natal rivers over an annual hydrological cycle. Only Sr:Ca, Ba:Ca and 87Sr:86Sr in otoliths were determined by their respective ratios in the ambient water. Sr:Ca ratios in stream waters fluctuated strongly on a seasonal basis, but these fluctuations, mainly driven by water flow regimes, were not recorded in the otoliths. Otolith Sr:Ca ratios remained constant during freshwater residency at a given site and were exclusively related to water Sr:Ca ratios during low flow periods. While interannual differences in otolith elemental composition among rivers were observed, this variability was minor compared to geographic variability and did not limit classification of juveniles to their natal stream. Success in discriminating fish from different sites was greatest using Sr isotopes as it remained relatively constant across years at a given location.

In vitro and in vivo evaluation of poly(methylidene malonate 2.1.2) microparticles behavior for oral administration.

The goal of this paper was to investigate the fate of novel poly(methylidene malonate 2.1.2) microparticles with different surface properties, i.e. prepared with or without polyvinylalcohol (PVA), after oral administration, using in vitro cell culture and an in vivo mice model. Incubation of particles with Caco-2 cells induced no cytotoxicity except for the microparticles prepared without PVA at high concentrations. At subtoxic concentrations, microparticles were highly associated to cells, independently of particles concentrations, particles surface properties (with or without PVA) or incubation time. Confocal microscopy analysis revealed that adsorption was the main phenomenon leading to the association of particles to cells. However, association was greater at 37 degrees C than at 4 degrees C, suggesting that an active process, such as endocytosis, could also occur. In vivo, radiolabeled particles were mainly found in luminal content and also adsorbed onto the epithelium. After 24 hours, more than 15% of PVA-free microparticles were still present in the gastrointestinal tract, compared to 5% for particles prepared with PVA. However, histological evaluation revealed low uptake of particles by Peyer's patches. As a conclusion, this study provided a good correlation between in vitro and in vivo evaluation. These particles could be useful for oral sustained release and delivery of drugs to intestinal and colon epithelium.

Intracranial metastases from an ovarian dysgerminoma in a 2-year-old dog.

A 2-year-old, intact female rottweiler was presented for signs of lethargy. A mass was ultrasonographically observed, cranial and lateral to the left kidney. Exploratory laparotomy revealed a mass in the left ovary that was diagnosed histopathologically as an ovarian dysgerminoma. Two weeks after surgery, the dog was readmitted with signs of peripheral vestibular disease that progressed to central vestibular disease. Magnetic resonance imaging of the brain revealed the presence of a mass in the caudal fossa. The histopathological diagnosis of the mass was metastases from the ovarian dysgerminoma.

Novel microparticulate system made of poly(methylidene malonate 2.1.2).

Formulation of PMM 2.1.2 microparticles entrapping ovalbumin as a model protein was achieved by using a double emulsion solvent evaporation method. Parameters such as the nature of the solvent, polymer concentration and polymer molecular weight were investigated. Preparation process led to the formation of spherical and smooth particles with a mean diameter of 5 microm, and an encapsulation efficiency and protein loading level of up to 16 and 2.9% w/w, respectively. After an initial burst of approximately 10%, the protein was released at a rate of less than 1% per day. This slow release kinetics of encapsulated ovalbumin in phosphate buffer indicates that most of the protein was encapsulated within the polymer matrix. Degradation of PMM 2.1.2 microparticles in the presence of esterases indicated that side chain hydrolysis of the polymer was the rate-determining step in bioerosion; cleavage of the ester side chain, which was further hydrolyzed to glycolic acid and ethanol, led to an acrylic acid and subsequent solubilization of the polymer. However, slow polymer backbone solubilization after degradation was observed.

Structure elucidation of methylidene malonate 2.1.2 cyclic trimers with mass spectrometry, liquid chromatography and nuclear magnetic resonance investigations.

The anionic polymerization of methylidene malonate 2.1.2. is able to yield four different molecule types. The major product obtained at pH 5.5 corresponds to a trisubstituted cyclohexanone formed by a back-biting reaction. A mixture of four diastereoisomer couples due to the presence of three asymmetric carbon atoms was produced in the same proportion. These results were deduced from mass spectrometry (MS), liquid chromatography MS (LC-MS) and 1H nuclear magnetic resonance (NMR) investigations.

Molecular mechanisms of the adsorption of a model protein (human serum albumin) on poly(methylidene malonate 2.1.2) nanoparticles.

PURPOSE: To understand the molecular mechanisms involved in protein-methylidene malonate 2.1.2 polymer interactions. METHODS: To assess the importance of electrostatic forces in polymer-protein interactions use was made of HSA and its derivatives, which were anionized by succinylation and aconitylation. Surface plasmon resonance measurements, using the three HSA molecules as immobilized ligands and polymer nanoparticles as analytes in the liquid phase, allowed the determination of initial kinetic constants and affinity constants at equilibrium at two different temperatures. RESULTS: Saturation of binding for the three proteins occurred at approximately 900 protein molecules/nanoparticle. The apparent affinity decreased with increasing electronegativity of the proteins. Surface plasmon resonance measurement of proteins, covalently linked to the chip matrix, showed a high affinity for the nanoparticles (K(A) approximately 10(10) M(-1) and confirmed the moderate decrease of affinity with increasing electronegativity of the modified albumins. Measurements at 25 and 37 degrees C showed no significant increase in the albumin-nanoparticle interactions. Dissociation of the proteins from the nanoparticles could only be realized with chaotropic salt solutions. CONCLUSIONS: These results suggest the molecular forces initiating the protein-nanoparticle interactions are mainly of electrostatic nature followed by stabilization by hydrophobic forces. The high affinity confirms the nanoparticles as excellent carriers for protein delivery.

Physico-chemical characterization, preparation and performance of poly (methylidene malonate 2.1.2) nanoparticles.

The present investigation confirms that initially implemented procedure to produce poly(methylidene malonate 2.1.2) (PMM 2.1.2) nanoparticles (Lescure et al. Pharm Res 1994;11:1270-77) lead to products mostly containing plasticizing oligomers which strongly lowered glass-transition temperature (Tg), dramatically reduced nanoparticle consistency and rendered them too sensitive to solubilization when diluted in an aqueous medium. From MALDI-TOF spectroscopy analysis, performed on intact colloids, emerged some structural information about these oligomeric species which could result from an intramolecular cyclization mechanism occurring soon in the course of the polymerization process. Thus, with the objective of overcoming these drawbacks, this contribution deals with the variations of manufacturing specifications such as pH and magnetic stirring speed to try and modulate molecular weight (MW) of nanoparticle constituents and reduce oligomer concentration. Although the analyses performed on these new nanoparticles were rather encouraging, the colloid formation yield became so low that it required the development of other methodologies, excluding a previous emulsion step, and allowing a controlled production of PMM 2.1.2-made nanoparticles having better physico-chemical characteristics while keeping good pharmaceutical capabilities.

Ultrasonographic appearance of ovarian tumors in 10 dogs.

Signalment, clinical history, physical examination, clinicopathologic, radiographic and ultrasonographic findings of 10 female dogs with histologically confirmed ovarian neoplasms were reviewed. Ultrasonographic images and reports were reviewed for (1) location, size, outer margins, and echogenicity of the mass(es), (2) presence of free abdominal fluid, (3) evidence of uterine abnormalities, and (4) signs of metastatic disease. The masses were classified according to their ultrasonographic pattern in solid, solid with cystic component, and cystic. The masses were ultrasonographically reported as being of ovarian origin in eight dogs, and this origin was included in the list of differentials in the remaining two dogs. When present, abdominal effusions and uterine abnormalities were diagnosed by means of ultrasound.

Immunochemical characterization of antibody-coated nanoparticles.

A new method using surface plasmon resonance (SPR) through the BIAcore was used to demonstrate the specific interaction between an anti-CD4 monoclonal antibody (IOT4a), adsorbed on poly(methylidene malonate 2.1.2) (PMM 2.1.2) nanoparticles, and the CD4 molecule. The results obtained were compared with the interaction of the same immunonanoparticles with rabbit anti-mouse Fc antibodies. The molar ratio (Fc)/(Fab) was 1, suggesting that the same number of epitopes on the Fc and the Fab fragments were accessible after IOT4a adsorption onto nanoparticles. Comparing the observed association rates of free antibody and antibody adsorbed on nanoparticles, the number of molecules of IOT4a antibody on PMM 2.1.2 nanoparticles was estimated as between 2.6 and 3 per nanoparticle. The properties of the antibody-coated nanoparticles are compatible with their use as antibody-targeted pharmacophores.