Effect of Direct Current Electric Fields on Cone Like Retinal Photoreceptor Cells.

INTRODUCTION: Studies show that electric fields are used as therapy during nerve and tissue injuries along with trans-retinal stimulation. However, cellular and molecular changes induced by such treatments remain largely unknown especially in retinal photoreceptor cells. In vitro studies show that direct current electric fields (dcEF) were known to influence cell division, polarity, shape, and motility. Here we could characterize for the first time the reactions of 661W, a retinal cone photoreceptor especially regarding organelle polarization, membrane polarization of mitochondria, O2 consumption, ATP/ADP ratio and gene expression. METHODS: The 661W cells were stimulated with a constant dcEF of field strength 5 V/cm during 30 min or 5 h depending on the parameters studied. RESULTS: In response to dcEF, the cells aligned perpendicular to the field by forming a leading edge with extended membrane protrusions towards the cathode. Using immunofluorescence and live cell imaging, we show that the cell membrane depolarized at the cathodal side. The microtubules spread into the direction of migration. Also, the microtubule organization center re-oriented into this direction. Concomitantly with the microtubules, actin filaments reorganized in an asymmetrical fashion mainly at the cathodal side. The Golgi apparatus, which is involved in many steps of actin synthesis, moved to the cathodal side. In the last 2 h of the 5 h experiment, microtubules positioned themselves at the rear (anodal side), like the nucleus. The averaged displacement of the whole cells under dcEF was 155% of control for 3 V/cm and 235% for 5 V/cm. The average speed increased by 142% and 243% respectively. Inside the cells mitochondria moved to the cathodal side, where the energy consuming producing processes take place. In this line, we measured an increase in ATP production and O2 consumption. Mitochondrial calcium was found more on the anodal side, at the site of the nucleus with its calcium delivering endoplasmic reticulum. In addition, oxymetry studies reveal an increased ATP synthesis by 115.2% and oxygen consumption by 113.3% 3 h after dcEF stimulation. An analysis of differentially expressed genes by RNA sequencing revealed an upregulation of genes involved in cellular movement, cell to cell and intracellular signaling, molecular transport, assembly and organization. CONCLUSIONS: The mechanisms found can enhance our understanding regarding the beneficial effects of EF treatment in retinal diseases.

A influência do pré-tensionamento mecânico na eficiência de transdutores piezoelétricos / Influence of pre-stressed mechanically in piezoelectric transducers efficiency

Os litotripsores utilizados em terapia urológica percutânea geralmente empregam transdutores constituídos de cerâmicas piezoelétricas e peças metálicas. Estes transdutores necessitam de pré-tensionamento mecânico para previnir a fratura da cerâmica quando submetidas a trações elevadas. Esta condição modifica, no entanto, o comportamento das cerâmicas piezoelétricas e conseqüentemente seu desempenho. Este trabalho apresenta um estudo do fator de acoplamento piezoelétrico e das perdas mecânicas dos transdutores pré-tensionados com o objetivo de caracterizar os níveis de compressão em que o transdutor seja mais eficiente.

The lithotriptors used in percutaneous urologic therapy generally employ transducers constituted of piezoelectric ceramics and metallic parts. These transducers need to be mechanically pre-stressed in order to avoid the fracture of the ceramic when under tensile forces. This effect however changes the ceramic behaviour and consequentelly its performance. This work shows a study on the coupling factor and on the mechanical losses of pre-stressed transducers aiming to find compression leveis in which the transducer become more efficient

Desenvolvimento de oxímetro para medidas em linhas de circulaçäo sangüínea extra-corpórea / Development of an oximeter for measures in line of extracorporeal blood circulation

Este trabalho descreve a construção de um protótipo de equipamento para medir a saturação de oxigênio (SaO2) nas linhas de perfusão arterial e venosa em procedimentos cirúrgicos com circulação extra-corpórea (CEC). O protótipo é constituído por dois sensores ópticos (um para linha arterial e outro para a venosa) e um módulo de processamento. Cada sensor contém dois LEDs e um fotodiodo que mede a luz transmitida na camada de sangue. O acoplamento entre o sensor e o sangue é obtido através de uma cubeta especial. A intensidade luminosa é digitalizada e processada para o cálculo da SaO2. O resultado é apresentado no painel frontal em um LCD. Testes In vitro mostraram boa correlação com valores de saturação determinados por aparelho comercial.

Abstract - This work desc1ibes a prototype for assessment of the oxygen saturation (OS) in flowing whole blood through the arterial and venous tubing used in extra-corporeal circulation (ECC) equipment dming cardiopulmonary bypass surgical procedures. The prototype utilizes an optical trar1sducer Vvith two LEDs and a photodiode operating in transmittance mode. A special cuvette was developed allowing easy attachment of the transducer to the tubings without causing hremolisis. The analog signal from light transmitted through blood is conve1ted to digital ar1d fed a microcontroller chip for further processing. The result is shown on the front panei on a LCD. ln vitro tests resulted in high coITelation between the readings provided by the prototype and a commercial blood gas analyzer

Desenvolvimento e construçäo de um perímetro assistido por computador / Development and construction of an perimeter assisted by microcomputer

Um mapeamento correto e preciso do campo visual é essencial para o diagnóstico e o tratamento de muitas anomalias em oftalmologia. Com a associação dos computadores à medida do campo visual, apareceram os primeiros perímetros automáticos, cuja aceitação é hoje uma realidade nos grandes centros clínicos. Este trabalho apresenta o desenvolvimento e a construção de um perímetro assistido por microcomputadores, objetivando desenvolver tecnologia nacional a baixo custo, e a sua difusão nas clínicas oftalmológicas e hospitais brasileiros.

Abstract - A correct and accurate map of the visual field is essential to the diagnostis and treatment of many abnormalities in opthalmology. The association of computers to visual tests resulted in the first automated perimeters. Nowadays, computerized perimetry has become a reality in major world clinicai centres. This work represents the development and construction of a computer assisted perimeter, aiming to develop national technology at low cost, and diffuse it in Brazilian hospitais and opthalmologists' offices