Narrow Results

Priming X-irradiation with 0.3-0.5 Gy induces radio-resistance in C57BL/6 strain of mice 2 weeks afterward. Elements in the bone marrow, sampled 11 days after challenging exposure to 5.0 Gy, were determined by PIXE. The challenging irradiation decreased Mg, P, S, K, Ca and Zn as well as dried bone marrow weight. The pre-irradiation enhanced recovery of these levels, indicating stimulated recovery of the metabolism in the tissue. Fe in both control (without pre-irradiation) and experimental groups increased to about twice the original value, showing elevated hemoglobin synthesis after challenging exposure. In previous studies we have reported that recovery of peripheral blood cell counts after sub-lethal irradiation was enhanced by the pre-irradiation. Further, study on accumulation of p53 and Bax proteins, which lead to apoptotic cell death, revealed that the pre-irradiation significantly suppressed accumulation of these proteins in the spleen after challenging irradiation with 3 Gy. These results and our present study suggest that the pre-irradiation decreased the spleen cell death, and favored re-growth of the spleen cells, resulting in stimulated recovery of metabolism for hematopoiesis in the bone marrow as well as in the spleen after challenging high dose irradiation. Stimulated recovery of Mg, P, S, K, Ca and Zn levels might indicate the importance of these elements in hematopoiesis.

Background and Purpose: In spite of major advances in cancer treatment, the prognosis of patients with oesophageal carcinoma remains poor. Squamous cell carcinoma and adenocarcinoma account for 95% of all oesophageal tumors, although other histological subtypes are occasionally seen. We aimed to evaluate whether Photofrin II can enhance the effect of ionizing radiation on oesophageal cancer in an in vitro tumor model. Material and Methods: A human oesophageal squamous cancer cell line (OE-21) and a human oesophageal adenocarcinoma cell line (OE-33) were evaluated with and without incubation with Photofrin II. Cells were irradiated using doses ranging from 0 to 8 Gy. The response rate of the cells to irradiation was evaluated by a tetrazolium-based colorimetric assay, similar to the MTT test, with the aim to determine the efficiency of Photofrin II as a radiation sensitizer in comparison to irradiation alone. Results: The OE-21 cell line demonstrated a significantly reduced cellular survival rate, when irradiated in the presence of Photofrin, as compared to a control group irradiated in the absence of Photofrin II. For the OE-33 cell line, no significant differences were found between the group treated with Photofrin II and the control group. Conclusion: Our results demonstrate in an in vitro model that Photofrin II may act as a radio-sensitizer in squamous cell oesophageal cancer, but not in oesophageal adenocarcinoma.