Validierung eines Zytotoxizitaetstests als Ersatzmethode zum Fischtest nach DIN 38412 Teil 31 (Phase II). T. 1-3 Ringversuch. Serumersatz. Mikrokerntest. Schlussbericht

Available from TIB Hannover: F97B1392+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Mutationsausloesung in Saeugerzellen durch niedrige Dosen ionisierender Strahlung

Es war das Ziel des Vorhabens, die Mutationsausloesung in Saeugerzellen durch niedrigere Dosen ionisierender Strahlung vor allem im Hinblick auf die Dosisleistungsabhaengigkeit zu untersuchen. Dazu wurde ein Verfahren zur kontinuierlichen Kultur entwickelt, mit dem es ermoeglicht wird, Saeugerzellen ueber mehrere Wochen in exponentieller Wachstumsphase zu halten. Es kamen dabei chinesische Hamsterzellen V79, menschliche TK6- und SP3-Zellen zur Anwendung. Die Exposition wurde mit einer "6"0Co-#gamma#-Quelle durchgefuehrt, wobei Dosisleistungen zwischen 2 und 200 mGy pro Stunde eingesetzt wurden. Zum Vergleich wurde in allen Faellen akute Dosiseffektkurven mit 300 KV-Roentgenstrahlung erstellt. Das zellkinetische Verhalten wurde mit Hilfe der Cytofluorometrie erfasst. Als wesentliches Ergebnis ist festzustellen, dass bei allen untersuchten Zellsystemen die Mutationsrate nach Exposition bei sehr geringen Dosisleistungen nicht niedriger liegt als bei akuter Bestrahlung. Fuer die menschlichen Zellen ergeben sich keine signifikanten Unterschiede, waehrend bei V79-Zellen sogar eine deutliche Erhoehung gefunden wurde. Eine Verringerung der Mutationsausbeute bei sinkender Dosisleistung, wie sie bisher generell angenommen wurde, konnte lediglich im mittleren Dosisleistungsbereich (50-500 mGy/Stunde) gefunden werden. Es muss betont werden, dass es sich bei dem untersuchten System um eine exponentielle proliferierende Zellpopulation handelt. Fuer Gewebe mit geringen Wachstumsfraktionen koennen moeglicherweise andere Verhaeltnisse vorliegen. Dennoch sind die Resultate von erheblicher Relevanz fuer die Abschaetzung des Risikos durch strahleninduzierte Mutationen sowohl auf genetischer als auch somatischer Ebene. (orig.)It was the aim of this study to investigate into the mutagenic effet of low dose ionizing radiation on mammalian cells, particularly as regards its relation to the dose rate. For this purpose, a procedure was developed for the continuous cultivation of mamalian cells that permitted expontential growth phases to be maintained over several weeks. The tests were carried out on V79 cells from Chinese hamsters as well as TK6 cells and SP3 cells from humans. The cells were challenged using a "6"0Co-gamma source, with dose rates varying between 2 and 200 mGy per hour. Acute dose-effect curves for 300 kV X-radiation were plotted as a reference standard. The key finding of the study was that frequencies of mutation determined in any of the cell systems following exposure to extremely small doses were no lower than those seen after acute irradation. The mutation rates were not significantly different in human cells and, surprisingly, even showed substantial increases for V79 cells. The generally expected decrease of mutation yields in proportion to the dose rate was confirmed by this study solely for the intermediate range (50-500 mGy/hour). This statement must be qualified by the fact that the systems investigated here were cell populations characterized by exponential growth. Circumstances may be different in tissues, where the growth fractions are only small. Nevertheless, the results still are of great relevance to the evaluation of risks from radiation-induced mutation, both at the genetic and somatic levels. (orig.)Available from TIB Hannover: RO 3190(381) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Comparison of wood smoke PM2.5 obtained from the combustion of FIR and beech pellets on inflammation and DNA damage in A549 and THP-1 human cell lines

The aim of this study was to investigate the effect on the induction of interleukin-8 of particulate matter (PM) from fir and beech pellets burnt in domestic appliances on two human cells lines, namely the lung epithelial cell line A549 and the promyelocytic cell line THP-1. The effects of PM2.5 obtained from combustion of beech and fir pellets were compared to reference diesel exhaust particulates (DEP). In parallel, wood smoke PM-induced genotoxicity and oxidative stress were also investigated in A549 cells. Cells were treated for different times (3\u201372 h) with increasing concentrations of PM2.5 obtained from sequential combustions of fir and beech pellets or reference DEP. Cell viability was assessed by lactate dehydrogenase leakage, and the release of interleukin-8 or CXCL8 (IL-8) was measured to evaluate the pro-inflammatory effect. Oxidative stress was evaluated by the 5(6)-carboxy-2\u2032,7\u2032dichlorofluorescein diacetate (DCFH-DA) assay and DNA damage by the alkaline comet assay and micronucleus frequency by flow cytometry. Both A549 and THP-1 cells responded in a dose- and time-related manner to wood smoke PM2.5 with IL-8 release, particles obtained from late combustions being the most active. THP-1 cells were more sensitive than A549 cells. On a mass base, similar effects were observed for both fir and beech PM2.5. However, the combustion of beech pellets generated approximately three times more PM2.5 than fir pellets. Regarding the mechanism of PM2.5 uptake, in both THP-1 and A549 cells, cytochalasin D prevented PM2.5-induced IL-8 mRNA expression and cytokine release, indicating a key role for actin polymerization in particles uptake and that the production of IL-8 correlated with particle phagocytosis. As signal transduction pathway involvement, in both THP-1 and A549 cells, PM2.5-induced IL-8 release could be completely blocked by the selective inhibitor SB203580, indicating a role of p38 MAPK activation. PM2.5 from both fir and beech pellets also induced modest DNA lesions dose related, measured as strand breaks, whereas no increase in the number of micronucleus was observed. Similar effects were observed with DEP, arguing against less dangerous effects of wood smoke particles than other categories of combustion-derived particles in the same size range. Overall, results suggest that combustion conditions can significantly affect the characteristics of particles and the consequent toxicity, and that different woods can generate different amounts of PM2.5