Untersuchungen zu Mechanismen der ernährungsbedingten Kolonkarzinogenese: Genspezifische Schäden in humanen Kolonzellen durch endogene Risikofaktoren

Im Rahmen dieser Arbeit wurde die Bedeutung ernährungsbedingter, endogen gebildeter Risikofaktoren (Wasserstoffperoxid als Modellsubstanz für oxidativen Stress, sowie trans-2-Hexenal und 4-Hydroxy-2-nonenal als reaktive Lipidperoxidationsprodukte) in den unterschiedlichen Stadien der humanen Kolonkarzinogenese hinsichtlich ihres Potentials, globale und genspezifische DNS-Schäden zu setzen, untersucht. Aus humanem Kolongewebe isolierte Primärzellen sowie LT97-Kolonadenom- und HT29clone19a-Kolonkarzinomzellen wurden mit H2O2 für 5 min bei 4 °C oder mit Hexenal bzw. Hydroxynonenal für 30 min bei 37 °C behandelt und die durch die Testsubstanzen induzierten Gesamt-DNS-Schäden mittels Einzelzellgelelektrophorese (Comet-Assay) quantifiziert. Die Reparatur der induzierten Schäden wurde durch Inkubation bei 37 °C über 120 min verfolgt. Genspezifische Schäden in den für die kolorektale Karzinogenese relevanten Genen (APC, KRAS bzw. TP53) wurden mittels Comet-FISH, einer Kombination aus Comet-Assay und Fluoreszenz-in-situ-Hybridisierung, analysiert. Für diese Untersuchungen kamen direkt oder indirekt markierte Sonden für das APC-, KRAS- und TP53-Gen zur Anwendung, wobei die Fluoreszenzsignale hinsichtlich Anzahl und Lage innerhalb der Zellen sowie hinsichtlich direkter Brüche ausgewertet wurden

Saliva as a matrix for human biomonitoring : Biomonitoring Methods, 2015

Purpose: Human biomonitoring ( HBM ) implies the assessment of internal exposure to hazardous substances by measuring the substances, their metabolites or reaction products, as well as effect parameters in human body fluids. Along with blood, plasma and urine, saliva is of increasing interest as an alternative matrix for HBM. Methods: This paper reviews studies that measure salivary background levels of hazardous substances, elevated levels after environmental or occupational exposure, as well as references which deal with physiological and toxicokinetic behaviour of saliva and salivary parameters, respectively. Results: The studies revealed that the determination of biomarkers in saliva is a promising approach for HBM, even if only few substances showed a satisfying correlation with exposure data or established biomonitoring matrices such as blood, plasma and urine. Saliva has been proven to be particularly suitable for substances of low molecular weight such as organic solvents, selected pesticides, cotinine, and for some specific trace elements. Besides several advantages, serious problems and limitations were identified. Above all, the complex interactions between substance properties, sampling procedure, sample preparation, measurement techniques or individual factors, and the salivary analyte level are discussed. Conclusions: A major conclusion of the review is that more scientific studies are needed in order to systematically collect data on parameters, influencing salivary analyte levels. Crucially required is a harmonisation of the sampling as well as the sample preparation techniques and procedures, which is indispensable to achieve an overall comparability and interpretability of salivary biomarker levels

Speichel als Matrix für das Humanbiomonitoring : Biomonitoring Methods in German Language, 2015

Purpose: Human biomonitoring (HBM) implies the assessment of internal exposure to hazardous substances by measuring the substances, their metabolites or reaction products, as well as effect parameters in human body fluids. Along with blood, plasma and urine, saliva is of increasing interest as an alternative matrix for HBM. Methods: This paper reviews studies that measure salivary background levels of hazardous substances, elevated levels after environmental or occupational exposure, as well as references which deal with physiological and toxicokinetic behaviour of saliva and salivary parameters, respectively. Results: The studies revealed that the determination of biomarkers in saliva is a promising approach for HBM, even if only few substances showed a satisfying correlation with exposure data or established biomonitoring matrices such as blood, plasma and urine. Saliva has been proven to be particularly suitable for substances of low molecular weight such as organic solvents, selected pesticides, cotinine, and for some specific trace elements. Besides several advantages, serious problems and limitations were identified. Above all, the complex interactions between substance properties, sampling procedure, sample preparation, measurement techniques or individual factors, and the salivary analyte level are discussed. Conclusions: A major conclusion of the review is that more scientific studies are needed in order to systematically collect data on parameters, influencing salivary analyte levels. Crucially required is a harmonisation of the sampling as well as the sample preparation techniques and procedures, which is indispensable to achieve an overall comparability and interpretability of salivary biomarker levels