Development of an Immunocapture-Based Polymeric Optical Fiber Sensor for Bacterial Detection in Water.

Conventional methods for pathogen detection in water rely on time-consuming enrichment steps followed by biochemical identification strategies, which require assay times ranging from 24 hours to a week. However, in recent years, significant efforts have been made to develop biosensing technologies enabling rapid and close-to-real-time detection of waterborne pathogens. In previous studies, we developed a plastic optical fiber (POF) immunosensor using an optoelectronic configuration consisting of a U-Shape probe connected to an LED and a photodetector. Bacterial detection was evaluated with the immunosensor immersed in a bacterial suspension in water with a known concentration. Here, we report on the sensitivity of a new optoelectronic configuration consisting of two POF U-shaped probes, one as the reference and the other as the immunosensor, for the detection of Escherichia coli. In addition, another methos of detection was tested where the sensors were calibrated in the air, before being immersed in a bacterial suspension and then read in the air. This modification improved sensor sensitivity and resulted in a faster detection time. After the immunocapture, the sensors were DAPI-stained and submitted to confocal microscopy. The histograms obtained confirmed that the responses of the immunosensors were due to the bacteria. This new sensor detected the presence of E. coli at 104 CFU/mL in less than 20 min. Currently, sub-20 min is faster than previous studies using fiber-optic based biosensors. We report on an inexpensive and faster detection technology when compared with conventional methods.

Detection of Bacillus anthracis and Bacillus anthracis-like spores in soil from state of Rio de Janeiro, Brazil.

BACKGROUND: Bacillus anthracis is the aetiologic agent of anthrax, a re-emerging, septicaemic, haemorrhagic and lethal disease that affects humans, domestic ruminants and wildlife. Plasmids pXO1 and pXO2 are attributes that confer pathogenicity to B. anthracis strains. This bacterium was used as biological weapon in the World Wars and in the biological attack in the United States of America at 2001. B. anthracis is classified as a Tier 1 bioterrorism agent by the Centers for Diseases Control and Prevention. Anthrax is recognised as a re-emerging disease. Several studies concerning the dynamics of B. anthracis cycle in soil revealed that nonpathogenic B. anthracis strains due to lack of pXO2 plasmid are commonly found in some types of soil. OBJECTIVES: This study aimed isolation and identification of B. anthracis spores in soil samples of the state of Rio de Janeiro, Brazil. METHODS: Phenotypic and genotypic approaches were used to identify isolates including MALDI-TOF/MS, motility test, susceptibility to gamma phage and penicillin, survey for pag and cap genes as surrogates of pXO1 and pXO2 plasmids, respectively, and sequencing of 16SrRNA-encoding gene. Physicochemical analysis of the soil samples were carried out to describe soil characteristics. FINDINGS: We observed the presence of one B. anthracis pXO1+ and pXO2- isolated from clay loam soil; one B. anthracis-like strain pXO1+ and pXO2-isolated from loamy sand; and 10 Bacillus spp. strains sensitive to phage-gamma that need better characterisation to define which their species were recovered from loamy sand. MAIN CONCLUSIONS: This work showed promising results and it was the first study to report results from an active surveillance for B. anthracis in Brazil.

Odontological light-emitting diode light-curing unit beam quality.

The distribution of light intensity of three light-curing units (LCUs) to cure the resin-based composite for dental fillings was analyzed, and a homogeneity index [flat-top factor (FTF)] was calculated. The index is based on the M2 index, which is used for laser beams. An optical spectrum analyzer was used with an optical fiber to produce an x-y power profile of each LCU light guide. The FTF-calculated values were 0.51 for LCU1 and 0.55 for LCU2, which was the best FTF, although it still differed greatly from the perfect FTF = 1, and 0.27 for LCU3, which was the poorest value and even lower than the Gaussian FTF = 0.5. All LCUs presented notably heterogeneous light distribution, which can lead professionals and researchers to produce samples with irregular polymerization and poor mechanical properties.

Tapered plastic optical fiber-based biosensor--tests and application.

Cells detection is crucial in microbiological analysis of clinical, food, water or environmental samples. However, currently employed methods are time consuming. Plastic optical fiber (POF) biosensors consist in a viable alternative for rapid and inexpensive scheme for detection. In order to study the sensitivity of tapers for microbiological detection, geometric parameters are studied, such as the taper waist diameter since the formation of taper regions are the key sensing element in this particular type of sensors. In this study, a series of POF taper sensors were prepared using a specially developed tapering machine, and the dispersion of geometric dimensions is evaluated, aiming to achieve the best tapering characteristics which will provide a better sensitivity on the sensor response. The fiber tapers that presented the finest results were those constructed in U-shaped (bended) configurations, with taper waist diameters ranging from 0.40 mm up to 0.50 mm. These fiber tapers were used as the main section of the monitoring device, and when chemically treated as immunosensors for the detection of bacteria, yeast and erythrocytes.

Avaliação de mecânica ventilatória por oscilações forçadas: fundamentos e aplicações clínicas / Analysis of the ventilatory mechanics by forced oscillations technique: main concepts and clinical applications

Requerendo apenas cooperação passiva e fornecendo novos parâmetros para análise da mecânica ventilatória, a técnica de oscilações forçadas (TOF) apresenta características complementares aos métodos clássicos de avaliação pulmonar. Neste trabalho, inicialmente é apresentada uma revisão dos princípios da técnica juntamente com uma discussão sobre suas vantagens e atuais limitações. A performance da técnica é comparada com a dos métodos clássicos na detecção de afecções respiratórias. As principais aplicações clínicas reportadas anteriormente na literatura, incluindo a avaliação da mecânica ventilatória infantil, estudos em neonatos, monitorização de pacientes sob ventilação mecânica, medicina ocupacional e avaliação de distúrbios no sono, são revisadas e discutidas. Com base na revisão efetuada e nos resultados obtidos em estudos efetuados em laboratório, os autores concluem que a TOF pode contribuir para um exame mais detalhado, assim como para facilitar a realização de testes de função pulmonar em condições nas quais as técnicas tradicionais não são adequadas.

Implantaçäo de um laboratório de ensaio de conformidade de instrumentos médico-hospitalares / Implantation of laboratory assay conformity of medico hospitalar instruments

A inexistência de certificação de conformidade de produtos médico-hospitalares no Brasil tem contribuido para proliferação de equipamentos sem qualidade e segurança. Entretanto a portaria 2.043 de 12 dezembro de 1994 do Ministário da Saúde institui uma política para garantir a qualidade dos produtos médico-hospitalares. Recentemente o Programa de Engenharia Biomédica iniciou processo de credenciamento de seu laboratório de Instrumentação para ensaios segundo a norma NBR IEC 601-1. Com a experiência adquirida neste processo este trabalho foi desenvolvido. Ele objetiva orientar os laboratórios da área de engenharia biomédica de como implantar um laboratório de certificação de conformidade dde equipamentos médico-hospitalares. Tal laboratório é o instrumento legal para avaliar a qualidade destes produtos

Abstract- ln Brazil, the Jack of conformity's certification of hospital products have contributed to the proliferation of equipment without quality and security. However the law number 2.043 of 12th December, 1994 from the Health's Ministry established a policy to guarantee the quality of hospital products. Recently the Biomedical Engineering Program stm1ed a processes to certificate its Instrumentation Laboratory for tests of conformity under the NBR IEC 601-1 standard. With the experience acquired in this process, this paper has been made. lt has the objective to guide the establishment of a test Jaboratory in the biomedical engineering area. This Jaboratory is the legal way to test and verify the quality ofthese products

Análise da proposta em frequência de sistemas de medida de pressäo empregados na área de fisiologia respiratória / Proposal analysis in frequency of pressure measurements systems used in respiratory physiology area

Neste trabalho, enfocamos brevemente os princípios de operação dos sistemas de medida de pressão e descrevemos um modelo elétrico para o mesmo. Reportamos os resultados da avaliação da resposta em frequência utilizando o transdutor diferencial Honneywell 163PC e diferentes tubos de conexão. Por fim, efetuamos uma discussão dos resultados com base no modelo proposto e nos resultados previamente reportados.

Abstract - ln this work, we made. a brief review of the pressure measurements systems operation principles and described an analog electrical model for these systems. The results of the frequency response using Honeywell 163 PC differential pressure transducer with different tubes are described. Finally, we made a discussion of the results based in the used model and in the previously reported results