Male Wistar rats were exposed to whole body irradiation with 14.35 Gy gamma rays after the adaptation to light/dark cycle (LD 12:12). Three groups of rats were examined: A) rats irradiated in the night and placed in the 12 h LD cycle again, B) rats irradiated in the day-time and placed in the 12 h LD cycle, and C) rats irradiated in the night and kept in constant darkness. All analyses were carried out in the dark. Radiation enhanced the activity of pineal N-acetyltransferase 3-4 days after exposure in all groups, in the C group significantly on the 4th day. Different light regimens during and after irradiation did not to affect the activity of this key enzyme of melatonin synthesis substantially.
Cellular response to ionizing radiation-induced damage depends on the cell type and the ability to repair DNA damage. Some types of cells undergo apoptosis, whereas others induce a permanent cell cycle arrest and do not proliferate. Our study demonstrates two types of response of embryonic diploid fibroblasts WI-38 to ionizing radiation. In the WI-38 cells p53 is activated, protein p21 increases, but the cells are arrested in G2 phase of cell cycle. Some of the cells die by apoptosis, but in remaining viable cells p16 increases, senescence associated DNA- damage foci occur, and senescence-associated beta-galactosidase activity increases, which indicate stress-induced premature senescence., J. Cmielová ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Ionizing radiation and somatostatin analogues are used for acromegaly treatment to achieve normalization or reduction of growth hormone hypersecretion and tumor shrinkage. In this study, we investigated a combination of somatostatin (SS14) with ionizing radiation of 60Co and its effect on reparation of radiation-induced damage and cell death of somatomammotroph pituitary cells GH3. Doses of γ-radiation 20-50 Gy were shown to inhibit proliferation and induce apoptosis in GH3 cells regardless of somatostatin presence. It has been found that the D0 value for GH3 cells was 2.5 Gy. Somatostatin treatment increased radiosensitivity of GH3 cells, so that D0 value decreased to 2.2 Gy. We detected quick phosphorylation of histone H2A.X upon irradiation by the dose 20 Gy and its colocalization with phosphorylated protein Nbs-1 in the site of double strand break of DNA (DSB). Number of DSB decreased significantly 24 h after irradiation, however, clearly distinguished foci persisted, indicating non repaired DSB, after irradiation alone or after combined treatment by irradiation and SS14. We found that SS14 alone triggers phosphorylation of Nbs1 (p-Nbs1), which correlates with antiproliferative effect of SS14. Irradiation also increased the presence of p-Nbs1. Most intensive phosphorylation of Nbs1 was detected after combined treatment of irradiation and SS14. The decrease of the number of the DSB foci 24 h after treatment shows a significant capacity of repair systems of GH3 cells. In spite of this, large number of unrepaired DSB persists for 24 h after the treatment. We conclude that SS14 does not have a radioprotective effect on somatomammotroph GH3 cells., M. Řezáčová, J. Čáp, D. Vokurková, E. Lukášová, J. Vávrová, J. Cerman, V. Mašín, N. Mazánková., and Obsahuje bibliografii a bibliografické odkazy
Several members of the TGF-ß family are known to effectively regulate the fate of hematopoietic progenitor cells in a complex and context-dependent manner. Growth differentiation factor-15 (GDF15) is a divergent member of the TGF-ß family. This stress-induced cytokine has been proposed to possess immunomodulatory functions and its high expression is often associated with progression of a variety of pathological conditions. GDF15 is also induced by chemotherapy and irradiation. Very few fundamental studies have been published regarding the effect of GDF15 in hematopoiesis. In this study, we analyzed the hematological status of untreated and γ-irradiated mice deficient for GDF15 as a result of genetic knock-out (KO), in order to clarify the regulatory role of GDF15 in hematopoiesis. Significant differences between GDF15 KO mice and their pertinent WT controls were found in the parameters of blood monocyte numbers, blood platelet size, and distribution width, as well as in the values of bone marrow granulocyte/macrophage progenitor cells. Different tendencies of some hematological parameters in the GDF15 KO mice in normal conditions and those under exposure of the mice to ionizing radiation were registered. These findings are discussed in the context of the GDF15 gene function and its lack under conditions of radiation-induced damage., M. Hofer, Z. Hoferová, J. Remšík, M. Nováková, J. Procházková, R. Fedr, J. Kohoutek, L. Dušek, A. Hampl, K. Souček., and Obsahuje bibliografii
We investigated hematopoiesis in untreated and ionizing radiation-exposed cyclooxygenase-2-deficient (COX-2 KO) mice. We performed a complex hematological analysis of 16 parameters in untreated COX-2 KO male mice or COX-2 KO male mice irradiated with the dose of 4 Gy of γ-rays and their wildtype littermates. At baseline, hematopoiesis was increased in COX-2-deficient mice, but attenuated by irradation in COX-2- deficient mice compared to wildtype. To conclude, the antiinflammatory action of the COX-2 genetic disruption plays a positive role in hematopoiesis under basal conditions but is detrimental following radiation exposure., M. Hofer, Z. Hoferová L. Dušek, K. Souček, A. Gruzdev., and Obsahuje bibliografii
We investigated and evaluated post-irradiation survival in cyclooxygenase-2-deficient (COX-2 KO) mice. Thirty-day survival following exposure of COX-2 KO mice to a lethal dose of 8.5 Gy of γ-rays was observed to be statistically significantly lower in both males and females, as well as when the sexes were merged, in comparisons with their wild-type counterparts. These findings were related to the previous observations concerning the detrimental influence of the COX-2 genetic disruption on hematopoiesis in sublethally irradiated mice. Deteriorated postirradiation survival of COX-2 KO mice confirmed the previously anticipated conclusion regarding negative influence of the antiinflammatory action of COX-2 deficiency under the conditions of exposure of the animals to ionizing radiation., M. Hofer, Z. Hoferová, A. Gruzdev, L. Dušek, M. Falk., and Obsahuje bibliografii
Gluteal muscle contracture (GMC) is a chronic fibrotic disease of gluteal muscles due to multiple etiologies. The main pathologic process is characterized by proliferation of fibroblasts and excessive accumulation of collagen in the extracellular matrix of the muscle. Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid and has been reported to be associated with various fibrotic diseases. However, the role of S1P in GMC remains unknown. Here in this articl e, High-perform ance liquid chromatography and immunohistochemistry were applied to evaluate S1P localization and expression in clinical samples from patients with GMC, Quantitative real time PCR, Western blot, and enzyme-linked immunosorbent assa y were used to explore the link between transforming growth factor-β 1 (TGF-β 1), plasminogen activator inhibitor-1 (PAI-1) and S1P. The results showed that S1P was enhanced in contraction band (CB) tissues. Studies using the cell proliferation and transformation assay indicated that exogenous S1P stimulated CB fibroblast proliferation in a time-depen dent manner and in higher concentration also in a dose-dependent manner. Furthermore, we demonstrated that S1P not only promoted collagen type I production, but also up-regulated mRNA and protein expression of transforming growth factor-β 1 and plasminogen activator inhibitor-1. These findings suggest that S1P may regulate increased synthesis of collagen and other fibrogenic factors, and significantly contributes to the process of gluteal muscle scarring in patients with GMC., A. Babicová ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Acute promyelocytic leukemia is characterized by a block of myeloid differentiation. The incubation of cells with 1 μmol/l all-trans retinoic acid (ATRA) for 72 h induced differentiation of HL-60 cells and increased the number of CD11b positive cells. Morphological and functional changes were accompanied by a loss of proliferative capacity. Differentiation caused by preincubation of leukemic cells HL-60 with ATRA is accompanied by loss of clonogenicity (control cells: 870 colonies/103 cells, cells preincubated with ATRA: 150 colonies/103 cells). D0 for undifferentiated cells was 2.35 Gy, for ATRA differentiated cells 2.46 Gy. Statistical comparison of clonogenity curves indicated that in the whole range 0.5-10 Gy the curves are not significantly different, however, in the range 0.5-3 Gy ATRA differentiated cells were significantly more radioresistant than non-differentiated cells. When HL-60 cells preincubated with 1 μmol/l ATRA were irradiated by a sublethal dose of 6 Gy, more marked increase of apoptotic cells number was observed 24 h after irradiation and the surviving cells were mainly in the G1 phase of the cell cycle, while only irradiated cells were accumulated in G2 phase. Our results imply that preincubation of cells with ATRA accelerates apoptosis occurrence (24 h) after irradiation by high sublethal dose of 6 Gy. Forty-eight hours after 6 Gy irradiation, late apoptotic cells were found in the group of ATRA pretreated cells, as determined by APO2.7 positivity. This test showed an increased effect (considering cell death induction) in comparison to ATRA or irradiation itself., M. Mareková, J. Vávrová, D. Vokurková, J. Psutka., and Obsahuje bibliografii