Showing papers by "Dietrich W. Lübbers published in 1997"
TL;DR: In a respiring normoxic tissue local P°1 may vary between values close to the arterial P°2 and values of almost zero P° 2, which is very well suited to create the necessary P°3 gradients.
165 citations
TL;DR: In this article, a phase-angle-sensitive imaging technique using the effect of luminescence lifetime quenching of ruthenium complexes incorporated into a polymer layer system was described.
Abstract: We describe a device capable of imaging distributions of surface PO2 as well as oxygen flux (e.g., into the human skin). Oxygen is monitored by a phase-angle-sensitive imaging technique using the effect of luminescence lifetime quenching of ruthenium complexes incorporated into a polymer layer system. The dyes are excited by modulated radiation of blue light-emitting diodes. The phase-shifted luminescence is detected by an intensified CCD camera. Several modulation techniques have been comparatively investigated. The obtained images correspond pixel-by-pixel to the local luminescence lifetimes, which are a direct measure for the distribution of surface PO2, or alternatively for the oxygen flux through a permeable diffusion barrier. For an illuminated sensor area of 10 cm2 and a spatial resolution of 1 mm at the sensor layer, the oxygen resolution is better than ΔPO2 = 0.3 torr in the absence of oxygen, and better than ΔPO2 = 4 torr at PO2= 160 torr.
72 citations
TL;DR: The quality of the local blood microcirculation and the cutaneous "respiration" are important factors in the diagnosis of circulatory disturbances, which may arise as a consequence of a number of clinical diseases as discussed by the authors.
Abstract: The quality of the local blood microcirculation and the cutaneous “respiration” are important factors in the diagnosis of circulatory disturbances, which may arise as a consequence of a number of clinical diseases. Some of the more important are smokers leg, burns, ulcerations, or tumors of the skin.
6 citations
TL;DR: There are some reports in literature which document that methodological difficulties and errors may arise when polarographic needle electrodes are used to measure local pO2 inSemisolid media as, for example, organs, blood vessel walls, tissue homogenates, pellets of alginate or semisolid layers of polypeptides or polysaccharides.
Abstract: There are some reports in literature which document that methodological difficulties and errors may arise when polarographic needle electrodes are used to measure local pO2 in semisolid media as, for example, organs, blood vessel walls, tissue homogenates, pellets of alginate or semisolid layers of polypeptides or polysaccharides. Different techniques of puncturing have been used to measure local pO2 profiles within tissues. Earlier, mostly continuous punctures were used (see1,2). The electrode was mounted on a microscopic drive3, on a micromanipulator moved manually or by a motor4,5. Measurements were performed mostly during insertion, but also during withdrawal6–8. Sometimes tissue was punctured first by a cannula and then, after withdrawal of the cannula, the pO2 was measured within the puncturing channel9. It was observed with the insertion of the electrode, tissue was indented; thus, puncturing caused the structure of tissue to be changed. To reduce dimpling stepwise puncture by hand10 or by a hydraulic microdrive was introduced, for example by using steps of a length of 50 or 100 µm11, 12 or of 10 µm13. Others proposed longitudinal vibration of the electrode, for example by 2 µm at 200–400 Hz14. There are now, for example, motor-driven stepping apparatus available (Nanostepper) which facilitate the application2,15.
5 citations