[en] Objective: To detect the method of reversing tumor multidrug resistance, and study the expression of colorectal carcinoma MDR1 genetic expression product P-glycoprotein (P-gp) in irradiated HCT-8 cells with different dose ionizing radiation. Methods: Flow cytometry was used to detect the change of P-gp. Results: positive cells percentage of P-gp increase obviously (P<0.01) after irradiated with 2Gy. When pre-irradiated with low dose (0.05Gy, 0.1 Gy), then irradiated with high dose, positive cell percentage of P-gp increase obviously (P<0.05), and so dose the positive cell percentage of P-gp (P<0.01) in the group of 0.2Gy + 2Gy. Compared with the group of 2Gy, positive cell percentage of P -gp decreases obviously (P<0.05) in the group of 0.1 Gy + 2Gy. Conclusion: low dose ionizing radiation can reverse radiogenic tumor multidrug resistance with high dose. (authors)

[en] Objective: To detect the expression of protein kinase C (PKC) in multidrug resistant cells of colorectal carcinoma after ionizing irradiation and observe the effect of PKC on occurrence and development of the multidrug resistant. Methods: The effect of PKC on multidrug resistant HCG-8 cells of colorectal carcinoma after treated with X-ray was detected by indirect immunofluorescence technique and flow cytometry. Results: Compared with sham- irradiation group, the positive percentage of PKC was increased significantly (P<0.05) after HCT-8 cells were treated with 2 Gy X-ray, the positive percentages of PKC were increased insignificantly after HCT-8 cells were treated with low dose (50, 100 mGy) before high dose of irradiation, the increasing of positive percentage of PKC in the group of 200 mGy + 2 Gy was significant (P<0.05). Compared with the group only treated with high dose of irradiation, the positive percentage of PKC in the group of 100 mGy + 2 Gy was decreased significantly (P< 0.05). Conclusion: High dose of ionizing irradiation can increase the expression of PKC in colorectal carcinoma significantly, reversely when HCT-8 cells are pretreated with low dose before high dose there is no additional increase of PKC expression. (authors)

[en] The change of cGMP of pineal gland in mice were observed with low dose radiation (LDR). The time-course changes of cGMP were detected by radioimmunoassay after WBI with 75 mGy X rays. It was shown that the levels of cGMP of pineal gland in mice began to decrease and reached its lowest peak at 18 h (p < 0.01) after WBI. And began to increase at 24 h and reached its highest peak at 72 h (p < 0.05). These results indicated that WBI with LDR could reduce to the cGMP levels of pineal gland cells in mice

[en] Objective: In the present study the authors observed the effect of low dose radiation (LDR) on cell cycle of pineal gland in mice. Methods: The distribution in the phase of the cell cycle was analyzed by flow cytometry after staining of pineal gland with prospidium iodine (PI) after WBI with 75 mGy X-rays. Results: It was shown that the percentage of G₀/G₁ phase and G₂ + M phase of pineal gland cells decreased after irradiation (P < 0.05), and meanwhile the percentage of S-phase of pineal gland cells increased after irradiation (P < 0.01). Conclusion: These results indicated that WBI with LDR could promote DNA synthesis of pineal gland cells in mice

[en] Objective: The effect of low dose radiation (LDR) on pineal gland in regulative function of testosterone (TS) in mice was determined in the study. Methods: The distribution of TS in the serum was analyzed by radioimmunoassay after WBI with 75 mGy X-rays. Results: Since 4 h after WBI the TS levels of serum in mice increased up to its highest peak at 8 h (P < 0.001), then returned to the sham-irradiation levels 12 h late, however, increased again after 24 h (P < 0.05), resulted in two peaks. Conclusion: The results indicated that whole-body low dose radiation might stimulate the regulative function of pineal gland and sex gland, increasing the level of TS

[en] Objective: To apply skin mesenchymal stem cells (MSCs) irradiated with different dosages of X-rays, instead of MSCs in the bone marrow to promote the proliferation of hematopoietic stem cells in vitro. Methods: To bone marrow cells were cultured on the skin MSCs layer irradiated with different dosages of X-rays in vitro. The number of bone marrow cells, the colony-forming-unit-macrophage-granulocyte (CFU-GM) were assayed after expansion and maintenance for 0-12 days. CFU-GM, colony-forming unit-erthroid (CFU-E), burst-forming-unit-erythroid (BFU-E) colony were assayed in the cultured supernatant of the skin MSCs. the effects of supporting hematopoiesis of irradiation on skin MSCs in fetal mice were observed. Results: The CFU-GM colonies were increased after bone marrow cells were cultured together with fetal mice skin MSCs irradiated with 6, 8, and 10 Gy X-rays, especially in 6 Gy X-rays group, it was 2.17 times as big as that in 0 Gy X-rays group. The cultured supernatant of skin MSCs irradiated with 6, 8 and 10 Gy X-rays could stimulate the growth of CFU-GM, CFU-E and BFU-E in vitro, there were significant differences compared with those in 0 Gy X-rays group (P<0.05), especially in 6 Gy X-rays group, they were 1.81, 3.94, and 3.51 times as big as those in 0 Gy X-rays group, respectively. Conclusion: Skin MSCs irradiated with certain dosage of X-rays in vitro have the function of sustaining the proliferation of hematopoietic cells, both irradiated MSCs layer and supernatant can increase the number of bone marrow cells colony. (authors)