Influence of the pulsed amperometric detection on the passivation of working electrode

Department of Analytical ChemistryKatedra analytické chemiePřírodovědecká fakultaFaculty of Scienc

Determination of creatinine using pulsed amperometry

Tato diplomová práce se zabývá stanovením kreatininu pomocí kombinace průtokové injekční analýzy (FIA) a vysokoúčinné kapalinové chromatografie (HPLC) s pulsní amperometrií, elektrochemickou technikou založenou na vkládání potenciálových pulsů na zlatou pracovní elektrodu. Stanovení probíhalo v zásaditém prostředí borátového pufru s roztokem kreatininu o koncentraci 1∙10-4 mol∙l-1 . Byla optimalizována délka čistícího a aktivačního pulsu a pH nosného roztoku. Na elektrodu byl nejprve vkládán čistící puls o velikosti +1,8 V po dobu 100 ms, dále byl vkládán aktivační potenciál -0,5 V po dobu 150 ms a poté měřící potenciál +0,2 V po 300 ms. Z proměřených pH bylo vybráno optimální pH=9,4. K borátovému pufru byl přidán methanol a později i acetonitril, aby bylo vyzkoušeno, zda je možné s těmito organickými rozpouštědly stanovovat kreatinin a zda bude možné průtokovou injekční analýzu nahradit metodou HPLC. Methanol v systému způsoboval deformaci píků, acetonitril v systému nezpůsoboval deformaci píků, při vyšším obsahu docházelo k destabilizaci základní linie. Dále byla proměřena kalibrační závislost v rozsahu koncentrací od 2,5 ∙ 10-4 mol∙l-1 do 5 ∙ 10-6 mol∙l-1 pomocí PAD v kombinaci s FIA. U vyšších koncentrací docházelo k rozdvojení píků. Pomocí PAD s HPLC byl proměřen samotný kreatinin o...This diploma thesis deals with the determination of creatinine using a combination of flow injection analysis (FIA) or high-performance liquid chromatography (HPLC) with pulse amperometry, an electrochemical technique based on the application of potential pulses on a gold working electrode. The determination was performed in a basic environment of borate buffer with creatinine concentration of 1∙10-4 mol∙l-1 . The lenght of the cleaning and activation pulse was optimized as well as the pH of the running buffer. A cleaning pulse of +1.8 V was first applied to the electrode for 100 ms, then an activation potential of -0.5 V was applied for 150 ms and then a measuring potential of +0.2 V for 300 ms. The optimal pH was selected as pH=9,4. Methanol and acetonitrile were added to the borate buffer to test whether creatinine could be determined in presence of these organic solvents and whether flow injection analysis could be transformed into HPLC. Methanol in the system caused peak deformation, acetonitrile did not cause the peak deformation in the system, at higher contents the baseline was destabilized. Furthermore, the calibration dependence in the range of concentrations from 2.5∙10-4 mol∙l-1 to 5∙10-6 mol ∙ l-1 was measured using PAD in combination with FIA. At higher concentrations, peaks splitted....Department of Analytical ChemistryKatedra analytické chemiePřírodovědecká fakultaFaculty of Scienc

La influencia de la publicidad en los TCA (anorexia y bulimia) en mujeres entre 18 y 35 años

En el presente trabajo de investigación se estudia la influencia que tiene la publicidad en una muestra seleccionada de mujeres entre 18 y 35 años, por ser estas las principales destinatarias de los mensajes publicitarios y tener impuesto un modelo estético relacionado con la delgadez. La investigación de campo se ha realizado sólo sobre la influencia de la publicidad pero, dentro del marco teórico de la anorexia y la bulimia, también se ha estudiado la evolución del canon de belleza en los últimos 30 años, diferentes pautas para el diagnóstico de estas enfermedades y la relación de estos trastornos con otros factores sociales y personales no publicitarios.Universidad de Sevilla. Grado en Publicidad y Relaciones Pública

Biological cells classification using bio-inspired descriptor in a boosting k-NN framework

International audienceHigh-content imaging is an emerging technology for the analysis and quantification of biological phenomena. Thus, classifying a huge number of cells or quantifying markers from large sets of images by experts is a very time-consuming and poorly reproducible task. In order to overcome such limitations, we propose a supervised method for automatic cell classification. Our approach consists of two steps: the first one is an indexing stage based on specific bio-inspired features relying on the distribution of contrast information on segmented cells. The second one is a supervised learning stage that selects the prototypical samples best representing the cell categories. These prototypes are used in a leveraged k-NN framework to predict the class of unlabeled cells. In this paper we have tested our new learning algorithm on cellular images acquired for the analysis of pathologies. In order to evaluate the automatic classification performances, we tested our algorithm on the HEp2 Cells dataset of (Foggia et al, CBMS 2010). Results are very promising, showing classification precision larger than 96% on average, thus suggesting our method as a valuable decision-support tool in such cellular imaging applications

Classification of biological cells using bio-inspired descriptors

International audienceThis paper proposes a novel automated approach for the categorization of cells in fluorescence microscopy images. Our supervised classification method aims at recognizing patterns of unlabeled cells based on an annotated dataset. First, the cell images need to be indexed by encoding them in a feature space. For this purpose, we propose tailored bio-inspired features relying on the distribution of contrast information. Then, a supervised learning algorithm is proposed for classifying the cells. We carried out experiments on cellular images related to the diagnosis of autoimmune diseases, testing our classification method on the HEp-2 Cells dataset of Foggia et al (CBMS 2010). Results show classification precision larger than 96% on average, thus confirming promising application of our approach to the challenging application of cellular image classification for computer-aided diagnosis

A Bio-inspired Learning and Classification Method for Subcellular Localization of a Plasma Membrane Protein

International audienceHigh-content cellular imaging is an emerging technology for studying many biological phenomena. statistical analyses on large populations (more than thousands) of cells are required. Hence classifying cells by experts is a very time-consuming task and poorly reproducible. In order to overcome such limitations, we propose an automatic supervised classification method. Our new cell classification method consists of two steps: The first one is an indexing process based on specific bio-inspired features using contrast information distributions on cell sub-regions. The second is a supervised learning process to select prototypical samples (that best represent the cells categories) which are used in a leveraged k-NN framework to predict the class of unlabeled cells. In this paper we have tested our new learning algorithm on cellular images acquired for the analysis of changes in the subcellular localization of a membrane protein (the sodium iodide symporter). In order to evaluate the automatic classification performances, we tested our algorithm on a significantly large database of cellular images annotated by experts of our group. Results in term of Mean Avarage Precision (MAP) are very promising, providing precision upper than 87% on average, thus suggesting our method as a valuable decision-support tool in such cellular imaging applications. Such supervised classification method has many other applications in cell imaging in the areas of research in basic biology and medicine but also in clinical histology

Viability of stressed Mycobacterium tuberculosis and association with multidrug resistance

This study investigated biological characteristics of recovered stressed M. tuberculosis isolates that failed to grow in differential culture media for phenotypic identification and in culture media containing anti-tuberculosis drugs for drug-susceptibility testing, despite of having grown in primary culture. It represents an improvement in the diagnosis of MDR tuberculosis and tuberculosis control

intravenous versus oral vinorelbine plus capecitabine as second line treatment in advanced breast cancer patients a retrospective comparison of two consecutive phase ii studies

Abstract Vinorelbine (i.v.) plus capecitabine (oral) combination therapy is active in anthracycline/taxane pretreated patients with metastatic breast cancer. Availability of oral vinorelbine provides this combination in an all-oral formulation. Two consecutive phase II trials differing only in vinorelbine administration routes evaluated their respective activities and tolerabilities in this population. In the i.v. group ( n = 38) disease control was 61% (37% PR, 24% SD), median TTP 6.8 months and median survival 11.3 months. In the oral group ( n = 38) disease control was 77% (5.4% CR, 34% PR, 38% SD), median TTP 7 months and median survival 10 months. G3–G4 neutropenia was more common in the oral group (

Novel Key Ingredients in Urinary Tract Health-The Role of D-mannose, Chondroitin Sulphate, Hyaluronic Acid, and N-acetylcysteine in Urinary Tract Infections (Uroial PLUS®)

: Urinary tract infections represent a common and significant health concern worldwide. The high rate of recurrence and the increasing antibiotic resistance of uropathogens are further worsening the current scenario. Nevertheless, novel key ingredients such as D-mannose, chondroitin sulphate, hyaluronic acid, and N-acetylcysteine could represent an important alternative or adjuvant to the prevention and treatment strategies of urinary tract infections. Several studies have indeed evaluated the efficacy and the potential use of these compounds in urinary tract health. In this review, we aimed to summarize the characteristics, the role, and the application of the previously reported compounds, alone and in combination, in urinary tract health, focusing on their potential role in urinary tract infections