RESUMO
We have developed a system with two epi-illumination sources, a DC-regulated lamp for transillumination and mechanical switches for rapid shift of illumination and detection of defined areas (250-750 æm²) by fluorescence and phosphorescence videomicroscopy. The system permits investigation of standard microvascular parameters, vascular permeability as well as intra- and extravascular PO2 by phosphorescence quenching of Pd-meso-tetra (4-carboxyphenyl) porphine (PORPH). A Pechan prism was used to position a defined region over the photomultiplier and TV camera. In order to validate the system for in vivo use, in vitro tests were performed with probes at concentrations that can be found in microvascular studies. Extensive in vitro evaluations were performed by filling glass capillaries with solutions of various concentrations of FITC-dextran (diluted in blood and in saline) mixed with different amounts of PORPH. Fluorescence intensity and phosphorescence decay were determined for each mixture. FITC-dextran solutions without PORPH and PORPH solutions without FITC-dextran were used as references. Phosphorescence decay curves were relatively unaffected by the presence of FITC-dextran at all concentrations tested (0.1 æg/ml to 5 mg/ml). Likewise, fluorescence determinations were performed in the presence of PORPH (0.05 to 0.5 mg/ml). The system was successfully used to study macromolecular extravasation and PO2 in the rat mesentery circulation under controlled conditions and during ischemia-reperfusion
Assuntos
Animais , Masculino , Ratos , Permeabilidade Capilar , Processamento de Imagem Assistida por Computador/métodos , Artérias Mesentéricas/metabolismo , Mesentério/irrigação sanguínea , Oxigênio/farmacocinética , Anticoagulantes/farmacologia , Dextranos/farmacologia , Fluoresceína-5-Isotiocianato/farmacologia , Corantes Fluorescentes/farmacologia , Luminescência , Microcirculação/metabolismo , Microscopia de Fluorescência/métodos , Microscopia de Vídeo/métodos , Porfirinas/farmacologia , Ratos WistarRESUMO
the morphology and density of nailfold capillaries were evaluated in patients with Type I and Type II diabetes mellitus and in healthy controls, using videocapillaroscopy. A protocol of well-defined capillary patterns was used. Diabetic patients had more tortuous and enlarged capillaries than controls. Nodular apical elongation was found only in diabetics and was more frequent in patients with a longer history of disease. Type II diabetic patientes with chronic clinical complications had a higher frequency of enlarged capillaries and nodular apical elongation. Glycemic control was without influence. Capillary densitu did not differ among the groups