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Alexander Gosslau

Publications and source records attributed to Alexander Gosslau.

3 recordsLinked to original sources
PubMed2006

Mitochondrial DNA deletions and the aging heart.

Mitochondrial DNA (mtDNA) mutations appear to be associated with a wide spectrum of human disorders and proposed to be a potential contributor of aging. However, in an age-dependent increase of the common 4977 bp deletion of human mtDNA still many unanswered questions remain. Comparing mtDNA copy levels in different tissues revealed that cardiac muscle had the highest, while the cortex cerebelli showed the lowest copy number of mtDNA in every donor. Intriguingly, mtDNA copy number showed no changes during aging. In heart tissue, the amount of 4977 bp mtDNA deletion increased in an age-dependent manner showing significant differences at the age of 40 years and older (p<0.005). In vitro studies analyzing human normal cells transfected with telomerase (BJ-T) revealed that oxidative stress (OS)--a well accepted promoter of aging--induced 4977 bp deletion and point mutations as demonstrated by real-time PCR and DHPLC analysis. Interestingly, OS induced apoptosis only in transformed human fibroblasts by activation of the intrinsic (mitochondrial-mediated) signalling pathway as indicated by morphological damage of mitochondria, DNA laddering and increase of the Bax/Bcl-2 ratio. In conclusion, in heart tissue, the amount of the 4977 bp deletion increased in an age-dependent manner and it was more detectable after the 4th decade of life, although there was some scatter in the data. Since, apoptosis was induced by the mitochondria-mediated pathway only in transformed cells, the role for apoptosis in normal tissue of the aging heart remains unclear.

Adolescent↗
PubMed2002

[Oxidative stress, age-dependent [correction of age-related] cell damage and antioxidative mechanisms].

Cellular oxidative stress is due to the production of reactive oxygen species (ROS), on the one hand, and weaknesses of the antioxidative defence, on the other. This is particularly true for cells with an active metabolism such as neurons and muscle cells, but it is also relevant for all other cell types. Hydrogen peroxide is an important member of ROS and is generated predominantly by mitochondria. In combination with reduced trace metals such as iron or copper, hydrogen peroxide is transformed into the highly reactive hydroxyl radical which causes damage to virtually all macromolecules. Oxidation of nucleic acids results in mutations while protein denaturation leads to enzyme defects and impairment of the cytoskeleton. Lipid peroxidation in cell membranes is strongly involved in the perturbation of ion homeostasis. Because this cell damage ultimatively causes cell death, oxidative stress initiates several diseases. Mitochondria play a major role in this context because they are the main source of endogenous oxidative stress and additionally function as an inducer of programmed cell death (apoptosis). Several strategies of antioxidative defence exist: While transition metals can be inactivated by chelating proteins (e.g., ferritin), ROS can be reduced enzymatically (e.g., by the glutathione peroxidase) or non-enzymatically by antioxidants (e.g., by vitamin E, vitamin C and glutathione). Stress proteins are implicated in the repair and transport of denatured proteins as well as in the inhibition of apoptosis.

Aged↗