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Biomedical subjects

M Nitsche

Publications and source records attributed to M Nitsche.

4 recordsLinked to original sources
PubMed2001

In vitro response of human dermal fibroblasts to X-irradiation: relationship between radiation-induced clonogenic cell death, chromosome aberrations and markers of proliferative senescence or differentiation.

PURPOSE: To analyse the relationship between radiation-induced clonogenic cell death, chromosome aberrations and markers of proliferative senescence or differentiation. MATERIALS AND METHODS: Plateau-phase human dermal fibroblasts from 18 donors were irradiated with graded doses of 1-6 Gy 200kV X-rays. Cell survival was determined by a colony-forming assay. Markers of differentiation or senescence were: spontaneous and radiation-induced clonal differentiation, which was determined morphologically and by the cellular potential to proliferate in clonal culture, also single-cell beta-galactosidase (beta-gal) staining at pH 6.0; and the secretion of transforming growth factor-beta (TGF-beta1) into the culture medium. Chromosome aberrations were determined as genomic yields of dicentric chromosomes and the excess acentric fragments, scored in Giemsa-stained metaphases, and as partial yields of reciprocal translocations for chromosomes 4, 7 and 9 using the FISH method. RESULTS: A broad spread was found in the shapes of the survival curves, with SF2 ranging from 0.041+/-0.015 to 0.63+/-0.05. Radiation-induced clonal differentiation as well as the secretion of TGF-beta1 was elevated in radiosensitive samples. With respect to chromosome aberrations, a significant correlation was found between clonogenic survival and radiation-induced excess acentric fragments. CONCLUSIONS: In the fibroblast cell system, in vitro radiosensitivity is determined not only by processes directly involved in DNA-damage recognition and repair, but also by intracellular signalling cascades, which will lead to differentiation processes.

Cell Death↗
PubMed2000

Slow cortical DC-potential responses to sweet and bitter tastes in humans.

Processing of hedonic stimulus quality is assumed to be accompanied by a tuning of cortical arousal and excitability. In this pilot study in 11 healthy humans scalp-recorded DC potentials were assessed during application of a sweet (sucrose) and bitter (quinine hydrochloride) taste, i.e., primary reinforcers of positive and negative quality. Muscular, ocular, and skin potential activity were controlled. Application of sucrose induced a widespread positive DC-potential shift with an amplitude of 40-50 microV and persisting for more than 120-s post-stimulus onset. Following administration of quinine hydrochloride, this positive shift was reduced, most distinctly between 48- and 88-s post-stimulus onset. The reduction appeared to be most consistent at anterior midline recording sites (Fz, Cz). It is assumed that the higher DC-potential positivity during sweetness than during bitterness points to a differential tuning of cortical excitability by a widespread decrease in depolarization of apical dendrites.

Adult↗