TY  - THES
A1  - Locher, Sanja
T1  - Analytische und Effektor-Studien von Catechinen
T1  - Analytical and Effector-Studies of Catechines
N2  - Catechine gehören als Flavan-3-ole zur Gruppe der Polyphenole. Aufgrund deren vielfältiger positiver Effekte auf den menschlichen Organismus nehmen sie in der Ernährungsforschung einen hohen Stellenwert ein. Dabei hat man bei den Flavan-3-olen meist nur die in der Natur vorherrschenden Isomere (+)-Catechin und (-)-Epicatechin untersucht, doch auch (-)-Catechin und (+)-Epicatechin sind Naturstoffe. Letztere findet man z.B. in Guarana oder in verarbeiteten Lebensmitteln, wie z.B. Kakao- und Kakaoerzeugnissen. Sie entstehen durch Epimerisierung unter den technologischen Bedingungen beim Rösten der Kakaobohnen und der Alkalisierung der Kakaomasse. Bei der Kakao-Verarbeitung werden ferner auch Catechin-C-Glykoside gebildet. Im ersten Teil dieser Arbeit wurden Stabilitätsstudien mit (+)-Catechin bei unterschiedlichen pH-Werten und Temperaturen durchgeführt. Der zweite Teil dieser Arbeit umfasst Untersuchungen von Catechin-Isomeren und zwei Catechin-C-Glykosiden auf ihren Einfluß auf die Lipoxygenase (LOX)- und Xanthinoxidase (XOD)-Aktivität. Für die Catechin-C-Glykosidbildung ist von uns eine neue Vorstellung zu deren Entstehungsmechanismus im Laufe der Lebensmittelverarbeitung entwickelt worden. Abschließend wurden anhand von Modelling-Studien die Effekte auf die Enzymsysteme erklärt.
N2  - As flavan-3-ols, catechins belong to the group of polyphenols. Due to their manifold positive effects on the human organism, catechins are of important significance in food research. Although only the two most abundant isomers in nature, (+)-catechin and (-)-epicatechin, have been studied in most cases; however, (-)-catechin and (+)-epi-catechin occur in nature as well. The latter are found i.e. in guarana or in processed food, as cacao and cacao products as the result of epimerization due to technological processing, i.e. while roasting the cocoa beans and alkalisation of the cacao mass. Catechin-C-glycosides are also formed during cacao processing. In the first part of this thesis stability studies with (+)-catechin at different pH values and temperatures were carried out. The second part of this work comprises analysis of catechin isomers and two catechin-C-glycosides on their influence on lipoxygenase (LOX)- and xanthinoxidase (XOD)-activity. For the building mechanism of catechin-C-glycosides during food processing a new hypothesis was developed. Finally the effects on enzyme systems were explained by means of modelling studies.
KW  - Stabilität
KW  - Catechine
KW  - Lipoxygenase <5->
KW  - Glykoside
KW  - Catechin C-glykoside
KW  - Xanthinoxidase
KW  - HPLC-MS
KW  - Stability
KW  - catechines
KW  - Lipoxygenase
KW  - Catechin C-glykosides
Y1  - 2011
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-65143
ER  - 
TY  - JOUR
A1  - Weis, Eva
A1  - Schoen, Holger
A1  - Victor, Anja
A1  - Spix, Claudia
A1  - Ludwig, Marco
A1  - Schneider-Raetzke, Brigitte
A1  - Kohlschmidt, Nicolai
A1  - Bartsch, Oliver
A1  - Gerhold-Ay, Aslihan
A1  - Boehm, Nils
A1  - Grus, Franz
A1  - Haaf, Thomas
A1  - Galetzka, Danuta
T1  - Reduced mRNA and Protein Expression of the Genomic Caretaker RAD9A in Primary Fibroblasts of Individuals with Childhood and Independent Second Cancer
JF  - PLoS ONE
N2  - Background: 

The etiology of secondary cancer in childhood cancer survivors is largely unclear. Exposure of normal somatic cells to radiation and/or chemotherapy can damage DNA and if not all DNA lesions are properly fixed, the mis-repair may lead to pathological consequences. It is plausible to assume that genetic differences, i.e. in the pathways responsible for cell cycle control and DNA repair, play a critical role in the development of secondary cancer. 

Methodology/Findings: 

To identify factors that may influence the susceptibility for second cancer formation, we recruited 20 individuals who survived a childhood malignancy and then developed a second cancer as well as 20 carefully matched control individuals with childhood malignancy but without a second cancer. By antibody microarrays, we screened primary fibroblasts of matched patients for differences in the amount of representative DNA repair-associated proteins. We found constitutively decreased levels of RAD9A and several other DNA repair proteins in two-cancer patients, compared to one-cancer patients. The RAD9A protein level increased in response to DNA damage, however to a lesser extent in the two-cancer patients. Quantification of mRNA expression by real-time RT PCR revealed lower RAD9A mRNA levels in both untreated and 1 Gy gamma-irradiated cells of two-cancer patients. 

Conclusions/Significance: 

Collectively, our results support the idea that modulation of RAD9A and other cell cycle arrest and DNA repair proteins contribute to the risk of developing a second malignancy in childhood cancer patients.
KW  - DNA methylation
KW  - Malignant neoplasms
KW  - Genes
KW  - Instability
KW  - Stability
KW  - Susceptibility
KW  - Checkpoints
KW  - Repair
KW  - Damage
Y1  - 2011
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-141838
VL  - 6
IS  - 10
ER  -