Peripheral neural cell sensitivity to mTHPC-mediated photodynamic therapy in a 3D in vitro model

Background: The effect of photodynamic therapy (PDT) on neural cells is important when tumours are within or adjacent to the nervous system. The purpose of this study was to investigate PDT using the photosensitiser, meta tetrahydroxyphenyl chlorin (mTHPC), on rat neurons and satellite glia, compared with human adenocarcinoma cell (MCF-7).Methods: Fluorescence microscopy confirmed that mTHPC was incorporated into all three cell types. Sensitivity of cells exposed to mTHPC-PDT (0–10 µg ml–1) was determined in a novel 3-dimensional collagen gel culture system. Cell death was quantified using propidium iodide and cell types were distinguished using immunocytochemistry. In some cases, neuron survival was confirmed by measuring subsequent neurite growth in monolayer culture.Results: MCF-7s and satellite glia were significantly more sensitive to PDT than neurons. Importantly, 4 µg ml–1 mTHPC PDT caused no significant neuron death compared with untreated controls but was sufficient to elicit substantial cell death in the other cell types. Initially, treatment reduced neurite length; neurons then extended neurites equivalent to those of untreated controls. The protocol was validated using hypericin (0–3 µg ml–1), which caused neuron death equivalent to other cell types.Conclusion: Neurons in culture can survive mTHPC-PDT under conditions sufficient to kill tumour cells and other nervous system cells

Ultrastructural alteration of tape-stripped normal human skin after photodynamic therapy

The effect of photodynamic therapy on tape-stripped normal human skin was explored ultrastructurally. Back skin areas of 3 healthy Caucasian volunteers, 2 men and 1 woman, were tape-stripped 10 consecutive times followed by topical treatment with 5-aminolevulinic acid (20%, w/w) for 4 hours under occlusion (Tegaderm(R)). Then the areas were irradiated for 30 minutes with Waldman PDT 1200 lamp (570-650 nm) with a total dose of 70 J/cm(2). Full-thickness punch biopsies were taken immediately after irradiation, and at 3 and 24 hours for electron microscopy examination. Photodynamic therapy caused morphological alterations mainly in the epidermis. Keratinocytes became oedematous and tonofilament bundles were split, but desmosomes remained normal. Many keratinocytes contained large intracellular vacuoles and extremely electronlucent cytoplasm implying cell damage. Although the majority of Langerhans cells were unaffected isolated Langerhans cells became apoptotic at 3 hours. The melanocytes preserved their normal morphology. The epidermal alterations recovered 24 hours after the irradiation. Inflammatory cell infiltrates were evident at 3 and 24 hours but no other dermal changes were observed. In conclusion, photodynamic therapy with 5-aminolevulinic acid affects mainly keratinocytes and can trigger apoptosis in Langerhans cells while melanocytes appear refractory, at least morphologically, to photodynamic therapy

Geringe Weiterbildungsteilnahme im Ruhrgebiet Weniger Beschaeftigte mit selbstaendigen und kreativen Taetigkeiten, seltenere Einfuehrung neuer Verfahren

'Die Teilnahme der Erwerbstaetigen an beruflicher Weiterbildung ist im Ruhrgebiet geringer als in Nordrhein-Westfalen. Informelle und eigeninitiative Lernformen haben beim Erwerb beruflichen Wissens im Ruhrgebiet geringeres Gewicht als im uebrigen NRW. Im Ruhrgebiet sind die betrieblichen Arbeitsanforderungen weniger kreativ und lernfoerderlich. Ein geringerer Anteil der Beschaeftigten berichtet von betrieblichen Innovationen. Der Rueckstand des Ruhrgebiets bei der Weiterbildung ist nicht allein durch eine im Vergleich zum uebrigen NRW andere Struktur der Betriebe oder Erwerbstaetigen zu erklaeren. Es bleibt ein mit den verwendeten Daten nicht erklaerter regionaler Faktor.' (Autorenreferat)SIGLEAvailable from Institut Arbeit und Technik im Wissenschaftszentrum Nordrhein-Westfalen, Gelsenkirchen (DE) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman