Dot-ELISA for the diagnosis of neurocysticercosis

The aim of the present study was to standardize and evaluate dot-Enzyme linked immunosorbent assay (Dot-ELISA), a simple and rapid test for the detection of cysticercus antibodies in the serum for the diagnosis of neurocysticercosis (NCC). The antigen used in the study was a complete homogenate of Cysticercus cellulosae cysts obtained from infected pigs and dotted on to nitrocellulose membrane. Test sera were collected from the patients of NCC, and control sera from patients with other diseases and healthy students and blood donors of the Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER) Hospital, Pondicherry, during a study period from 2001 to 2003. Dot-ELISA detected antibodies in 14 of 25 (56%) in clinically suspected cases of NCC, 13 of 23 (56.5%) in CT/MRI proven cases of NCC and 2 of 25 (8%) each in non-cysticercal CNS infection controls and healthy controls. The test showed a sensitivity of 56.25%, specificity of 92%, positive predictive value of 87.09%, and negative predictive value of 70.76%. Results of the present study shows that the Dot-ELISA as a simple test can be used in the field or poorly equipped laboratories for diagnosis of NCC .

Febrifugine derivative antimalarial activity: quantum mechanical predictors

Plasmodium falciparum resistant strain development has encouraged the search for new antimalarial drugs. Febrifugine is a natural substance with high activity against P. falciparum presenting strong emetic property and liver toxicity, which prevent it from being used as a clinical drug. The search for analogues that could have a better clinical performance is a current topic. We aim to investigate the theoretical electronic structure by means of febrifugine derivative family semi-empirical molecular orbital calculations, seeking the electronic indexes that could help the design of new efficient derivatives. The theoretical results show there is a clustering in well-defined ranges of several electronic indexes of the most selective molecules. The model proposed for achieving high selectivity was tested with success.

Dot-Elisa for evaluation of hydatid cyst wall, protoscoleces and hydatid cyst fluid antigens in the serodiagnosis of cystic echinococcosis

The aim of the present study is to evaluate cyst wall and protoscolex as an alternate source of antigen in serodiagnosis of cystic echinococcosis (CE). A total of 90 blood samples, 30 each of confirmed CE cases, disease controls and healthy controls were collected. Dot-ELISA using cyst wall, protoscolex and cyst fluid were used to demonstrate anti-hydatid antibodies. The sensitivity of Dot-ELISA using cyst wall, protoscolex and cyst fluid was 96.66%, 86.66% and 93.33% respectively and the specificity of the assay was 70% for Dot-ELISA using cyst fluid, protoscolex and cyst wall antigens. Results of the present study show that cyst wall and protoscolex can also be an useful source of antigen in detection of hydatid antibodies in the serodiagnosis of CE.

Frequency of human toxocariasis in a rural population from Cajamarca, Peru determined by DOT-ELISA test

The aim of this study was to estimate the frequency of human toxocariasis in Cauday district, Cajamarca, Peru, using a dot-ELISA test. From June to October 2005, a total of 256 adult subjects were studied. Blood samples were collected for serology by a dot-ELISA test and for hematological examination. Parasitological examination was also carried out in stool samples to check cross-reactions in the dot-ELISA. The frequency observed was 44.92%, with a significant higher proportion of positivity in male subjects. From subjects with positive serology, 45.6% had respiratory symptoms, 40.44% abdominal pain, 32.35% hepatic symptoms, 14.7% cutaneous signs, 13.23% ocular manifestations, 43.38% eosinophilia, and all of these were statistically associated to serology. Among the population evaluated, 90.23% (231/256) were parasitized. From subjects with positive serology, 92.17% had at least one intestinal parasite and the most frequent were: Blastocystis hominis (68.38%), Giardia lamblia (28.68%), Hymenolepis nana (20.0%), Ascaris lumbricoides (15.65%), Entamoeba histolytica/E. dispar (13.24%), Cyclospora cayetanensis (4.41%), Cryptosporidium sp. (1.47%), Enterobius vermicularis (0.87%), Strongyloides stercoralis (0.87%), Taenia sp. (0.87%), and Trichuris trichiura (0.87%). The rate of false positives in the dot-ELISA test was improved by serum absorption each with A. suum antigens, with a decrease of cross-reactions. In conclusion, human toxocariasis is highly frequent in this population and some risk factors like dog/cat ownership, presence of pets within house, and previous history of geophagia were observed in the present study.

Quantum dots: synthesis, functionalization and bioconjugation for biological applications

Dissertation presented to obtain the Ph.D degree in Engineering Sciences and Technology

Dot enzyme-linked immunosorbent assay (dot-ELISA) for schistosomiasis diagnosis using dacron as solid-phase

Dacron and nitrocellulose were evaluated as matrices for the dot enzyme linked immunosorbent assay (dot-ELISA) for schistosomiasis and compared to indirect immunofluorescence (IMF). Titration of sera from 18 schistosomiasis patients against soluble worm antigen preparation (SWAP) was carried out and sera from healthy individuals from non-endemic areas were used as controls. The IMF was less sensitive than the dot-ELISAs, although the difference was not statistically significant (p > 0.05). The dot-ELISA based on nitrocellulose was as sensitive as that using dacron. Stability did not differ between nitrocellulose and dacron. Specificity was lower when dacron was used than when nitrocellulose was used, although the difference was not statistically significant (p > 0.05). In conclusion, this work showed that nitrocellulose and dacron performed similarly in dot-ELISA, suggesting that they may be used alternatively in population surveillance in endemic areas.

Electrochemical and quantum chemical investigations of the insecticide fipronil.

This work describes an electrochemical and quantum chemical investigation of the fipronil insecticide. Cyclic voltammetry (CV) and square wave voltammetry (SWV) experiments were performed over a graphite-polyurethane (GPU) composite electrode. The fipronil molecule presents an one?electron irreversible oxidation reaction. Profiting the SWV signal a square wave stripping voltammetry (SWSV) procedure to determine the fipronil molecule in a 0.10 mol L-1 Britton-Robinson buffer solution, pH 8.0 was developed with accumulation potential and time of 0.50 V and 120 s, respectively. The limits of detection and quantification were 0.80 and 2.67 ?g L-1, respectively. Recovery tests were performed in three natural waters samples with values ranging from 99.67 to 101.37%. Quantum chemical studies showed that the nitrogen atom of the pyrazole group is the most probable oxidation site of the fipronil molecule.

Antioxidant extraction process for Andean Oca by a photodiode array detector using response surface methodology

Application of Experimental Design techniques has proven to be essential in various research fields, due to its statistical capability of processing the effect of interactions among independent variables, known as factors, in a system’s response. Advantages of this methodology can be summarized in more resource and time efficient experimentations while providing more accurate results. This research emphasizes the quantification of 4 antioxidants extraction, at two different concentration, prepared according to an experimental procedure and measured by a Photodiode Array Detector. Experimental planning was made following a Central Composite Design, which is a type of DoE that allows to consider the quadratic component in Response Surfaces, a component that includes pure curvature studies on the model produced. This work was executed with the intention of analyzing responses, peak areas obtained from chromatograms plotted by the Detector’s system, and comprehending if the factors considered – acquired from an extensive literary review – produced the expected effect in response. Completion of this work will allow to take conclusions regarding what factors should be considered for the optimization studies of antioxidants extraction in a Oca (Oxalis tuberosa) matrix.

Design of assemblies based on polymer-coated quantum dots and organic dye

During last years, photophysical properties of complexes of semiconductor quantum dots (QDs) with organic dyes have attracted increasing interest. The development of different assemblies based on QDs and organic dyes allows to increase the range of QDs applications, which include imaging, biological sensing and electronic devices.1 Some studies demonstrate energy transfer between QDs and organic dye in assemblies.2 However, for electronic devices purposes, a polymeric matrix is required to enhance QDs photostability. Thus, in order to attach the QDs to the polymer surface it is necessary to chemically modify the polymer to induce electronic charges and stabilize the QDs in the polymer. The present work aims to investigate the design of assemblies based on polymer-coated QDs and an integrated acceptor organic dye. Polymethylmethacrylate (PMMA) and polycarbonate (PC) were used as polymeric matrices, and nile red as acceptor. Additionally, a PMMA matrix modified with 2-mercaptoethylamine is used to improve the attachment between both the donor (QDs) and the acceptor (nile red), as well as to induce a covalent bond between the modified PMMA and the QDs. An enhancement of the energy transfer efficiency by using the modified PMMA is expected and the resulting assembly can be applied for energy harvesting.

Quantum field theory approach to the optical conductivity of strained and deformed graphene

The computation of the optical conductivity of strained and deformed graphene is discussed within the framework of quantum field theory in curved spaces. The analytical solutions of the Dirac equation in an arbitrary static background geometry for one dimensional periodic deformations are computed, together with the corresponding Dirac propagator. Analytical expressions are given for the optical conductivity of strained and deformed graphene associated with both intra and interbrand transitions. The special case of small deformations is discussed and the result compared to the prediction of the tight-binding model.

Dinámica Cuántica de Sistemas Complejos: Fundamentos y Aplicaciones. Quantum Dynamics in Complex Systems: Fundamentals and Aplications.

El procedimiento de revertir la dinámica colectiva (diablillo de Loschmidt apresurado) mediante un pulso de radio frecuencia, permite generar un Eco de Loschmidt, es decir la refocalización de una excitación localizada. Alternativamente, en acústica es posible implementar un Espejo de Reversión Temporal, que consiste en la progresiva inyección de una débil excitación ultrasónica en la periferia de un sistema, para construir una excitación que se propaga "hacia atrás". Así, podemos afirmar que es posible revertir y controlar la dinámica. Sin embargo, aún no se posee una comprensión detallada de los mecanismos que gobiernan estos procedimientos. Este proyecto busca responder las preguntas que posibilitan esta comprensión.

Quantum phase transitions in magnetic systems: application of coupled cluster method

Magdeburg, Univ., Fak. für Naturwiss., Diss., 2009

Disposable, micro-fluidic biosensor array for online analysis of adherent cells activity combining quartz crystal resonators and impedance measurement techniques

Magdeburg, Univ., Fak. für Elektrotechnik und Informationstechnik, Diss., 2011