Navegando por Palavras-chave "Urease"
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- ItemAcesso aberto (Open Access)Adsorção de metais poluentes e enzimas em filmes híbridos de Langmuir-Blodgett imobilizados com polissacarídeos algais/fosfolipídios(Universidade Federal de São Paulo, 2014-05-20) Brito, Audrey Kalinouski de [UNIFESP]; Caseli, Luciano [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Currently, many biological substances extracted from algae have received special attention because of its intrinsic characteristics which can be applied in different areas of biotechnology. Based on this context, the current work have investigated the action of exopolysaccharides (EPS) from the microalgae Cryptomonas tetrapirenoidosa when it is immobilized on Langmuir-Blodgett films (LB) constructed with the lipid dioctadecyldimethylammonium bromide (DODAB). The main objective was to evaluate if the mixed ultrathin film, once formed as a device, is able to interact, detect and maybe remove pollutant metals from aqueous solutions as well as to serve as a suitable matrix for enzyme immobilization in order to produce biosensors. DODAB is spread on the air-water interface and the EPS is injected into the aqueous subphase. First it was built these monolayers supported on aqueous solution that were characterized with surface pressure-area isotherms, curves of adsorption kinetics, infrared spectroscopy for surfaces (PM-IRRAS) and ultraviolet-visible spectroscopy (UV-vis). After that, the monolayer was transferred to solid support by using de Langmuir-Blodgett (LB) technique. These mixed LB films (DODAB + EPS) were immersed in solutions with metals that usually cause environmental problems. Thus, these films could be tested on PM-IRRAS, an infrared spectroscopy for surfaces. This technique could evaluate the interaction between the ions and the film. On the other hand, it was estimated the ability of the enzyme urease to be immobilized with DODAB and EPS on LB films on glass support. Then, the LB films were immersed in a urea + bromocresol purple solution to investigate, with ultraviolet - visible spectroscopy (UV-vis), the catalytic activity of urease when it is immobilized. The activity was determined through the analysis of a band in 586 -590 nm. Furthermore, the LB films were analyzed by atomic force microscopy, and the results could confirm that the urease on the film maintained its activity and could confirm that the hybrid LB films can interact with metal ions. Consequently, it can be concluded that these LB films are promising for build a biosensor for urea and another for metal ions.
- ItemAcesso aberto (Open Access)Avaliação do teste rápido da urease conservado em geladeira(Instituto Brasileiro de Estudos e Pesquisas de Gastroenterologia - IBEPEGE Colégio Brasileiro de Cirurgia Digestiva - CBCD Sociedade Brasileira de Motilidade Digestiva - SBMD Federação Brasileira de Gastroenterologia - FBGSociedade Brasileira de Hepatologia - SBHSociedade Brasileira de Endoscopia Digestiva - SOBED, 2000-07-01) Ornellas, Laura Cotta [UNIFESP]; Cury, Marcelo de Souza [UNIFESP]; Lima, Vinícius Machado de [UNIFESP]; Ferrari, Angelo Paulo [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)The rapid urease test is an accurate and cheap method, which results are readily available, and broadly used for routine Helicobacter pylori infection diagnosis. Aim - The evaluation of rapid urease test stored in refrigerator at 4 °C (SRUT) compared to regular rapid urease test. Patients and Method - Endoscopic biopsies were obtained from gastric antrum in 104 consecutive patients. Diagnosis of Helicobacter pylori infection was accomplished by rapid urease test, histology and rapid urease test stored (kept in refrigerator by a period ranging from 1 to 8 days). Results - Infection was considered present if both rapid urease test and histology were positive. Helicobacter pylori was present in 45/104 patients (42%). Rapid urease test stored had specificity comparable to rapid urease test (93%), with sensitivity of 88%. Conclusion - We concluded that rapid urease test can be stored in refrigerator for up to 1 week, without loss of clinical applicability, and that can make the test even easier to use for routine Helicobacter pylori tests in a busy endoscopy unit.
- ItemSomente MetadadadosConjugated polymers nanostructured as smart interfaces for controlling the catalytic properties of enzymes(Academic Press Inc Elsevier Science, 2016) Barbosa, Camila Gouveia [UNIFESP]; Caseli, Luciano [UNIFESP]; Peres, Laura Oliveira [UNIFESP]The search for new molecular architectures to improve the efficiency of enzymes entrapped in ultrathin films is useful to enhance the effectiveness of biosensors. In this present work, conjugated polymers, based on thiophene and fluorine, were investigated to verify their suitability as matrices for the immobilization of urease. The copolymer poly[(9,9-dioctylfluorene)-co-thiophene], PDOF-co-Th was spread on the air-water interface forming stable Langmuir monolayers as determined by surface pressure-area isotherms, polarization-modulation reflection-absorption infrared spectroscopy (PM-IRRAS), and Brewster angle microscopy (BAM). Urease was incorporated in the floating monolayers being further transferred to solid supports as mixed Langmuir-Blodgett (LB) films. These films were then characterized with transfer ratio, fluorescence spectroscopy, PM-IRRAS and atomic force microscopy, confirming the co-transfer of the enzyme as well as its structuring in beta-sheets. The catalytic activity was detected for urease, with a lower reaction rate than that encountered for the homogeneous environment. This was attributed to conformational constraints imposed to the biomacromolecule entrapped in the polymeric matrix. (C) 2016 Elsevier Inc. All rights reserved.
- ItemAcesso aberto (Open Access)Decrease in prevalence of Helicobacter pylori infection during a 10-year period in Brazilian children(Instituto Brasileiro de Estudos e Pesquisas de Gastroenterologia - IBEPEGE Colégio Brasileiro de Cirurgia Digestiva - CBCD Sociedade Brasileira de Motilidade Digestiva - SBMD Federação Brasileira de Gastroenterologia - FBGSociedade Brasileira de Hepatologia - SBHSociedade Brasileira de Endoscopia Digestiva - SOBED, 2008-06-01) Kawakami, Elisabete [UNIFESP]; Machado, Rodrigo Strehl [UNIFESP]; Ogata, Silvio Kazuo [UNIFESP]; Langner, Marini [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)BACKGROUND: Decreasing prevalence of H pylori infection has been reported in some countries. AIM: To evaluate the prevalence of Helicobacter pylori infection in a 10-year period in children submitted to upper digestive endoscopy. METHODS: It was a retrospective observational study. The records of 1,165 endoscopies performed during a 10-year period in a public hospital of the City of São Paulo, SP, Brazil, in patients up to 18-year-old. Only the first endoscopy was considered. Helicobacter pylori infection was defined by the rapid urease test, performed with one fragment of antral mucosa. Chi-square for trend has been estimated to compare Helicobacter pylori prevalence across the period. RESULTS: The main indication for endoscopy was epigastric pain (47.4%). There were 392 patients with H pylori infection (33.6%), 12.8% being infants, 19.4% toddlers, 28.8% schoolchildren and 46.3% adolescents. Prevalence was 60.47% in the first year of the study and 30.43% in the last. Among the less than 6-year-old patients there was a decrease in infection prevalence from 25% for the 1993-6 period to 14.3% in the 2000-02 period, while among the over 12-year-old patients the decrease was from 55.5% in the first period to 39.6% in the latter. The decrease in H pylori infection prevalence was more intense within patients with epigastric pain, in which prevalence has decreased from 48.2% (92/191) in 1993-6, to 41.9% (65/155) in 1997-9 and 27.7% (57/206) in 2000-02. CONCLUSION: The study suggests a significant decrease in the prevalence of H pylori infection regarding the studied patients. The trend was mainly observed in the younger age group and in patients with epigastric pain.
- ItemSomente MetadadadosFilmes Nanoestruturados Mistos De Copolímero Conjugado E Urease Para Biossensores De Ureia(Universidade Federal de São Paulo (UNIFESP), 2017-09-21) Barbosa, Camila Gouveia [UNIFESP]; Philadelphi, Laura Oliveira Peres [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)The search for new molecular architectures to improve the efficiency of trapped enzymes in ultrathin films has increased the effectiveness of biosensors. In this work, a conjugated copolymer derived from thiophene and fluorene was investigated aiming to analyze its capacity of acting as a matrix for the immobilization of urease. Based on this fact, the copolymer poly[(9,9-dioctylfluorene)-co-thiophene] was synthesized, using the Suzuki’s reaction, and characterized by Infrared spectroscopy, Raman, UV-vis, fluorescence and thermogravimetry. Langmuir films of the polymer were prepared in the air-water interface. Urease was incorporated in the Langmuir monolayers and the properties of the mixed films were investigated in detail by surface pressure-area isotherms, polarization modulationinfrared reflection-adsorption spectroscopy (PM-IRRAS) and Brewster angle microscopy (BAM). The Langmuir films prepared were transferred to solid supports forming Langmuir- Blodgett (LB) films with 1, 3, 5 and 9 layers. These films were then characterized by their transfer rate, fluorescence specrtroscopy, PM-IRRAS and atomic force microscopy, confirming the material transfer and conformational changes in the enzyme structure after the deposition. In the 9-layer-film, the catalytic activity of urease was detected, with reaction rate lower than in the homogeneous environment, which was attributed to conformational restrictions imposed to the enzyme retained in the copolymer. The films were also characterized electrochemically, demonstrating their viability to detect urea. The mixed film prepared with 9 layers was also evaluated as an electrochemical biosensor using the cyclic voltammetry technique, in which a peak due to the electrooxidation of urea was noted at 0.6 V, and the chronoamperometry analysis which allowed the detection of the products formed in the reaction at 0.3 V. The chronoamperometry results showed a linear range of work for the urea concentrations from 1 to 4 mM, which demonstrates the feasibility of this system for urea detection.
- ItemAcesso aberto (Open Access)Helicobacter pylori e doença péptica: estudo comparativo de métodos diagnósticos(Instituto Brasileiro de Estudos e Pesquisas de Gastroenterologia - IBEPEGE Colégio Brasileiro de Cirurgia Digestiva - CBCD Sociedade Brasileira de Motilidade Digestiva - SBMD Federação Brasileira de Gastroenterologia - FBGSociedade Brasileira de Hepatologia - SBHSociedade Brasileira de Endoscopia Digestiva - SOBED, 2008-09-01) Caetano, Alaor; Felix, Valter Nilton; Coimbra, Fernando Tadeu Vanucci; Ganc, Arnaldo José [UNIFESP]; Faculdade de Medicina de São José do Rio Preto; Universidade de São Paulo (USP); Universidade Federal de São Paulo (UNIFESP)Prospective endoscopic study of 150 patients revealed chronic gastritis in 109 (72.6%), gastric ulcer in 6 (4%), chronic duodenitis in 9 (6%) and duodenal ulcer in 26 (17.4%). Searching for Helicobacter pylori, positive urease test was observed in 103 (68.67%), histologic evidence in 104 (69.33%) and positive serologic test in 98 (65.33%), without statistical difference. The urease test is recommended in the diary medical practice, for the patients who also will benefit themselves with the endoscopic diagnosis. On the other hand, the serologic test is useful when the endoscopy of the upper digestive tract cannot or must not be realized.