Fate of D3 mouse embryonic stem cells exposed to X-rays or carbon ions.

The risk of radiation exposure during embryonic development is still a major problem in radiotoxicology. In this study we investigated the response of the murine embryonic stem cell (mESC) line D3 to two radiation qualities: sparsely ionizing X-rays and densely ionizing carbon ions. We analyzed clonogenic cell survival, proliferation, induction of chromosome aberrations as well as the capability of cells to differentiate to beating cardiomyocytes up to 3 days after exposure. Our results show that, for all endpoints investigated, carbon ions are more effective than X-rays at the same radiation dose. Additionally, in long term studies (≥8 days post-irradiation) chromosomal damage and the pluripotency state were investigated. These studies reveal that pluripotency markers are present in the progeny of cells surviving the exposure to both radiation types. However, only in the progeny of X-ray exposed cells the aberration frequency was comparable to that of the control population, while the progeny of carbon ion irradiated cells harbored significantly more aberrations than the control, generally translocations. We conclude that cells surviving the radiation exposure maintain pluripotency but may carry stable chromosomal rearrangements after densely ionizing radiation.

In-vitro evaluation of the corrosion behavior of orthodontic brackets.

OBJECTIVE: The number of bracket systems for orthodontic therapy increases significantly. One major concern of newly developed orthodontic devices is aspects of corrosion and biocompatibility. MATERIAL AND METHODS: In this study, nine bracket systems made of different material and from various design principles were tested with respect to their corrosion behavior. Electrochemical and static immersion tests with subsequent measurement of nickel ion release were performed. In addition surface alterations of the brackets after corrosion were documented by scanning electron microscopy. Studies of corrosion behavior were performed according to the DIN/ISO standard 10271 for corrosion testing of dental materials. RESULTS: All systems showed traces of corrosion after electrochemical testing. However, after static immersion testing only minor corrosion defects could be documented and the measured nickel ion release was far below critical limits. CONCLUSIONS: All tested systems seem to be biocompatible and applicable for orthodontic therapy. The measured nickel values are far below the daily dietary intake level. A static immersion test combined with the nickel ion release measurement seems to be more relevant for the determination of biocompatibility than the electrochemical testing.

Parameters of self-organization in Hydra aggregates.

Self-organization has been demonstrated in a variety of systems ranging from chemical-molecular to ecosystem levels, and evidence is accumulating that it is also fundamental for animal development. Yet, self-organization can be approached experimentally in only a few animal systems. Cells isolated from the simple metazoan Hydra can aggregate and form a complete animal by self-organization. By using this experimental system, we found that clusters of 5-15 epithelial cells are necessary and sufficient to form de novo head-organizing centers in an aggregate. Such organizers presumably arise by a community effect from a small number of cells that express the conserved HyBra1 and HyWnt genes. These local sources then act to pattern and instruct the surrounding cells as well as generate a field of lateral inhibition that ranges up to 1,000 microm. We propose that conserved patterning systems in higher animals originate from extremely robust and flexible molecular self-organizing systems that were selected for during early metazoan evolution.

Isotype profile and clinical relevance of anticardiolipin antibodies in Sjögren's syndrome.

The purpose of this study was to determine the occurrence and clinical value of anticardiolipin antibodies in patients with Sjögren's syndrome. Thirty one patients with primary Sjögren's syndrome (all women, mean (SD) age 48.3 (11.2) years) and 32 patients with secondary Sjögren's syndrome with rheumatoid arthritis (all women, mean (SD) age 54.9 (11) years) were studied. IgG, IgM, and IgA anticardiolipin antibodies were determined by a standard enzyme linked immunosorbent assay (ELISA) technique. Anticardiolipin antibodies were found in five patients (16%) with primary Sjögren's syndrome and in seven patients (22%) with secondary Sjögren's syndrome. There was no correlation between anticardiolipin antibodies and the clinical features of the antiphospholipid syndrome (thrombotic events, fetal loss, thrombocytopenia) or extraglandular manifestations of Sjögren's syndrome (arthritis, skin lesions, myositis, polyneuropathy, central nervous system disease, pulmonary and renal disease) in either group. Among the various serological features studied, anticardiolipin antibodies correlated with antinuclear antibodies and antibodies to RNP only in patients with primary Sjögren's syndrome. These results indicate that although anticardiolipin antibodies are often found in serum samples from patients with Sjögren's syndrome, their clinical significance remains unclear.

Circulating immune complexes in systemic scleroderma.

Circulating immune complexes were detected by the immunoelectrophoretic method in 18 of 29 (62 per cent) of patients with systemic scleroderma. The presence of immune complexes did not correlate with that of antinuclear antibodies to dsDNA, DNP, RNP, and Sm. The mean levels of immunoglobulins G, A, and M as well as of C3 were significantly higher in patients with systemic scleroderma than in blood donors.