The Temperature Dependence of Protoporphyrin IX Production in Cells and Tissues

The formation of protoporphyrin IX (PpIX) in human skin during topical application of 5-aminolevulinic acid (ALA) was found to be strongly temperature dependent, with an activation energy of about 17 kcal/mol. This temperature dependence is mainly related to porphyrin production and not to ALA penetration into the skin. The penetration of ALA into mouse and human skin was almost temperature independent. The activation energy of PpIX production in mouse skin was practically identical with that in human skin. The activation energy of ALA uptake by cells in vitro was about 10 kcal/mol and that for PpIX production was about 13 kcal/mol. The latter activation energy was within the error limits similar to that for the activity of the enzyme porphobilinogen deaminase, suggesting that this enzyme might represent a rate-limiting step for PpIX production in living tissue.     

The influence of temperature on photodynamic cell killing in vitro with 5-aminolevulinic acid

Cell survival was investigated after exposing cells in vitro to different temperatures before or after photodynamic therapy with 5-aminolevulinic acid. The photodynamic process was found to be temperature dependent. Cells exposed for 1h to 41 degrees C before light exposure or to 7 degrees C after light exposure showed decreased survival. Furthermore, the photobleaching rate of protoporphyrin IX in the cells was found to increase with increasing temperature during the light exposure. Thus, the photodynamic effect with 5-aminolevulinic acid may be enhanced by heating the tumour area before, and by cooling it immediately after the treatment.     

HPLC determination of the composition and stability of blackcurrant anthocyanins

High-performance liquid chromatography with UV and mass spectrometry detectors are used to monitor the composition and stability of anthocyanins in blackcurrants harvested from different Ribes nigrum breeds at various ripeness phases. The highest amounts of pigments are found in overripe berries. The concentration of anthocyanins is higher in the berries of late blackcurrant breeds (Vakariai and Ben Alder). Delphinidin- 3-rutinoside is the dominant component in the reddish color berries (onset of ripening), and cyanidin-3-rutinoside is a major pigment in the black ones (ripe berries). Studies of the effect of temperature and light on the stability of the main pigments in blackcurrants show that aqueous solution prepared from a dry colorant is more stable when compared with the liquid water and ethanol extracts of coloring substances. Cyanidin-3-rutinoside is found to be the most thermally stable anthocyanin.     

Topical bioadhesive patch systems enhance selectivity of protoporphyrin IX accumulation

In clinical 5-aminolevulinic acid (ALA)-based photodynamic therapy (PDT) of skin tumors it is desirable to develop vehicles that minimize the penetration of ALA through normal stratum corneum and maximize it through the compromised stratum corneum of the tumors to improve tumor selectivity. We have designed a bioadhesive patch, which may be able to achieve this aim. It induces levels of protoporphyrin IX (PpIX) in skin overlying tumors similar to those induced by the proprietary cream (Porphin) but at the same time induces less PpIX to form in normal skin and at distant sites. The mechanisms of action of the patch, as compared with that of the cream, were studied by means of Cuprophan barriers that mimic compromised tumor stratum corneum and in a mouse model with transplanted tumors.     

Perturbation of the poles of the scattering matrix under variation of the boundary condition

The behavior of the poles z_n(), n=1,2,... of the scattering matrix of the operatorl u=–u(x), x , (u/n)+(x)u|=0 as 0 is considered. It is proved that |z_n()–z_n|=0(^(1/2)qn), where q_n is the order of the pole of the scattering matrix for the operator ₀u=–u, u/=0.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 117, pp. 183–191, 1981.     

Protoporphyrin IX fluorescence kinetics in UV-induced tumours and normal skin of hairless mice after topical application of 5-aminolevulinic acid methyl ester

Accumulation of protoporphyrin IX (PpIX) was investigated in normal skin and UV-induced tumours in hairless mice after topical application of a cream containing 2, 8 or 16% of 5-aminolevulinic acid methyl ester (ALA-Me). Higher levels of PpIX were measured in tumours compared to normal skin. The maximal amount of PpIX was reached at 1.5, 3 and 4 h after 2, 8 and 16% ALA-Me application, respectively. Higher tumour to normal skin PpIX fluorescence ratios were measured after application of 8 and 16% ALA-Me than after application of 2%. After irradiation with a broad spectrum of visible light from a slide projector, more than 90% of PpIX was bleached by fluences of 36 and 48 J/cm2, at fluence rates of 10 and 40 mW/cm2 respectively. At these fluences, the PpIX photobleaching rate was significantly higher (P<0.05) in normal mouse skin than in tumours. In addition, for a given fluence, more PpIX was photobleached at the lower fluence rate (10 mW/cm2) than at the higher fluence rate (40 mW/cm2) in normal skin (P<0.001) as well as in tumours (P<0.05) after exposure to 24 J/cm2 of light. In conclusion, the highest tumour to normal skin PpIX ratio was observed 3 h after application of 8% ALA-Me, suggesting that light exposure should be performed at this time in order to achieve an optimal PDT effect in this tumour model.     

Vergleichende Untersuchungen zur Filtrationswirksamkeit von Membranfiltern

Zusammenfassung Die Filtrationswirksamkeit von insgesamt 17 Sartorius-Membran-, Millipore- und Gelman-Filtern für in 4%iger wäßriger NaCl-Lösung suspendierte Testpartikel unterschiedlicher Form und Größe (Latex, Colanylgrün, Bakterienzellen) wurde experimentell untersucht. Dies erfolgte mittels elektronischer und mikrobiologischer Filtratanalysen. Die wichtigsten Untersuchungsergebnisse sind in Tabellenform zusammengestellt und werden kurz diskutiert.

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Summary Efficiencies of 17 different types of membrane filters (products of the Sartorius Membranfilter GmbH., Göttingen, the Millipore Filter Corporation, Bedford, Massachusetts, and the Gelman Instrument Co., Chelsea, Michigan) have been tested by electronic and microbiological analysis of the filtrates of particle suspensions. The test particles (polystyrene latex, colanyl green, bacterial cells — in all cases suspended in 4% saline) were representatives of different types with respect to their size and shape. The most essential results are presented by 2 tables. A short discussion is included.

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Herrn G. König danke ich für seine außerordentlich gewissenhafte experimentelle Mitarbeit. Zugleich danke ich den Herren Dr. D. Thon und R. Gröpl von der Sartorius Membranfilter GmbH., Göttingen, sowie meinem Kollegen Dr. H.-J. Preußer für Diskussionen und Anregungen, letzterem darüber hinaus für die elektronenmikroskopische Untersuchung der Bakterien-Hemmformen.