EXPRESSION OF REG1Α, GAST AND TGFB1 GENES IN CONDITIONS OF STRESSINDUCED GASTRIC MUCOUS LESIONS DEVELOPMENT AND HEALING IN RATS.

Analysis of Reg1a gene expression in rat gastric mucosa under development and healing of stress-induced lesions was carried out. Increased expression of Reg1a was observed after 1 hour of stressor impact - 2,1 times, and achieved the maximum level expression after 3 hours of stress exposure - 3,5 times, that occurred on the background of lipid peroxidation intensification and antioxidant system dysfunction. The sharp decrease in 1,6 and 2 times of Reg1a gene expression was shown in 12 and 24 hours respectively after termination of the stressor action. Analysis of Gast gene expression did not confirm that gastrin stimulated Reg1a expression in gastric mucosa under water immersion restraint stress. The positive correlation between Reg1a and Tgfb1 genes expression was determined in the dynamics of stress-induced gastric lesions' development and healing, which may indicate the involvement of Tgfb1 to acceleration of lesion's healing.

Enhanced cytotoxicity of photoexcited fullerene C60 and cisplatin combination against drug-resistant leukemic cells.

AIM: To evaluate the viability of leukemic cells sensitive (L1210S) and resistant (L1210R) to cisplatin, ROS production and free cytosolic Ca(2+) concentration under treatment with cisplatin or its combination with photoexcited fullerene C60. METHODS: Cell viability was assessed by the MTT reduction assay. Light-emitting diode lamp (2.45 J/cm(2)) was used for photoexcitation of intracellular accumulated fullerene C60. Free cytosolic calcium concentration ([Ca(2+)]i) and ROS production in cells were estimated with the use of fluorescent probes Indo-1 and 2',7'-dichlorodihydrofluorescein diacetate (DCF-DA), respectively. RESULTS: It is shown that viability of L1210R cells wasn't changed under treatment with cisplatin in concentration range 0.1-10 µg/ml. 50% and 30% decrease of L1210S cells were observed after 24 h of incubation with cisplatin at concentrations 5 and 1 µg/ml, respectively. Intensification of extranuclear cytotoxic effects (ROS production and [Ca(2+)]i increase) after treatment with 1 µg/ml was detected in L1210S, but not in L1210R cells. The most strongly pronounced increase of ROS production and [Ca(2+)]i in both L1210 cell lines was revealed in dynamics after combined treatment with cisplatin (1 µg/ml) and photoexcited fullerene C60 (10(-5) M) and was followed by decreased viability of not only L1210S, but of L1210R cells as well.. CONCLUSION: Combined treatment with photoexcited C60 and cisplatin allowed to decrease effective concentration of cisplatin against parental L1210 cells and to increase sensibility of resistant cells to the drug.

[Calcium homeostasis in the thymocyte apoptosis II. Accumulation of calcium in mitochondria and endoplasmic reticulum].

The activity of energy-dependent Ca2+-accumulation systems in rat thymocytes mitochondria and endoplasmic reticulum (ER) in control and at the early stage of X-irradiation or H2O2-induced apoptosis were determined in experiments using the model of digitonin-permeabilized cells with addition of thapsigargin and ruthenium red. The mitochondrial Ca2+-transporting system proved to be more sensitive to both apoptotic stimuli. The stationary level of Ca2+, accumulated in mitochondria and initial rate of Ca2+ accumulation in ER were reduced 15 min after H2O2 treatment. The parameters of mitochondrial Ca2+-accumulation system in irradiated cells were decreased 30 min after irradiation. Cyclosporin A almost completely inhibited DNA fragmentation in irradiated and partly--in peroxide-treated cells. The mitochondrial calcium homeostasis imbalance is suggested to be an early event in thymocytes apoptosis initiation.

[Calcium homeostasis during thymocyte apoptosis. I. Increase in cytosolic Ca2+ concentration at the early stage of apoptosis induced by hydrogen peroxide]. / Kal'tsievyi gomeostaz v timotsitakh pri apoptoze. I. Povyshenie kontsentratsii tsitozol'nogo Ca2+ na rannei stadii apoptoza, indutsirovannogo peroksidom vodoroda.

The concentration of free cytosolic Ca2+ ([Ca2+]i), 45Ca2+ entry and the level of reduced glutathione (GSH) after x-irradiation in a dose of 4.5 Gy or 0.1 mM H2O2-treatment were investigated in isolated rat thymocytes during the period preceding electrophoretically detected DNA intranucleosomal fragmentation. Using fura-2 it was shown that the level of [Ca2+]i in X-irradiated thymocytes was not changed as compared with the control, while the GSH content was increased. The gradual increase in [Ca2+]i along with GSH level falling was detected in the H2O2-treated cells. 45Ca2+ entry in the cells exposed to apoptogenic stimuli was not enhanced. After addition of H2O2 to the cells previously treated with thapsigargin further [Ca2+]i increase in both normal and nominally calcium-free medium was detected. Cyclosporine A inhibited Ca2+-mobilizing effect of H2O2, but did not prevent it completely. The role of intracellular calcium depots in calcium homeostasis disturbance during oxidative stress and apoptosis is discussed.