The fluorescence and photosensitivity of endogenously synthesized protoporphyrin IX (PPIX) is increasing used for the diagnosis and treatment of malignant and certain non-malignant diseases. A selective accumulation of PPIX can be induced by application of 5-aminolevulinic acid (5-ALA), which is a precursor of PPIX in the cellular biosynthetic pathway of heme.
The purpose of this study was to monitor the in vivo accumulation of PPIX in different locations of the skin after oral ingestion and to determine the pharmacokinetics of 5-ALA and PPIX in human blood plasma for various routes of application. At the same time we wanted to achieve an optimal treatment scheme but also study possible side-effects of 5-ALA administration.
After oral application of 5-ALA in a concentration of 40 mg kg−1 body weight, the fluorescence intensities of PPIX in the skin showed maxima between 6.5 and 9.8 h depending on the location and decreased to values lower than 5% related to the maximum after a mean time of about 40 h. The measured absolute intensities of PPIX fluorescence varied strongly between different patients and different locations on one patient. In the plasma of blood samples, PPIX could be detected via its fluorescence for all studied routes of application with the exception of the ointment, where PPIX levels were below the detection limit of 1 μg l−1. The highest mean concentration of 742 μg l−1 PPIX in the plasma was measured 6.7 h after oral application. For inhalation of 5-ALA, a mean maximum concentration of 12 μg l−1 could be detected 4.1 h after application, for intravesical instillation, the mean maximum concentration was found to be 1 μg l−1 2.9 h after application. The kinetics of 5-ALA in the plasma peaked much earlier with a maximum concentration of 32 mg l−1 about 30 min. after oral administration. The 5-ALA levels did not exceed normal reference values after topical application.
The results of our experiments suggest that for a systemic application of 5-ALA side-effects in sensitive patients cannot be excluded. 相似文献
This work demonstrates a multifiber optical catheter with bending control of the distal end, whose main use is to collect
Raman signal for biospectroscopy. Also, a method for fiber background subtraction is presented, allowing removal of fiber
emission peaks from gross Raman spectrum. The fiber optic catheter with seven fiber optics wrapped up in a resin and a biocompatible
flexible teflon tube has been modified to incorporate a mechanical device with gauntlet, which allows bending of the distal
extremity to access a desired location obeying the anatomy of the organ. The mechanical device (gauntlet) was built halfway
from the catheter proximal excitation tip, allowing the bending of the distal end of about 38 mm diameter. Dispersive Raman
spectra at 785 nm excitation wavelength from samples were measured without and with bending (from 120 mm decreasing to 14
mm) of the distal end of the catheter. An optical catheter without the gauntlet was used as a reference. Results demonstrated
that both catheters (with bending mechanism and standard one) had about the same Raman signal when the device was bent semicircularly
to 38 mm diameter (bending limit for the mechanism), with negligible implication to the Raman signal-to-noise relation (SNR)
from sample. When both catheters were bent in a full turn, the Raman signal decreased to about 40% when bending reached 14
mm diameter, mainly due to losses introduced by changes in the fiber total internal reflection. The background removal was
efficient, with minimum residual from fiber peaks. This optical catherer could be very useful in laser diagnosis and clinical
applications, introducing a way to control the fiber tip position and angle on the tissue or organ.
Published in Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 1, pp. 97–102, January–February, 2007. 相似文献