核辐射对大深度快速上浮脱险致减压病大鼠相关指标的影响*

目的: 探讨不同剂量核暴露后不同时间对大深度快速上浮脱险致减压病大鼠模型的发病率、死亡率及损伤指标的影响。方法: 80只SD雄性大鼠,随机分成空白对照组、脱险对照组和6个干预组(4 Gy辐射后4 h脱险、6 Gy辐射后4 h脱险、12 Gy辐射后4 h脱险、4 Gy辐射后8 h脱险、6 Gy辐射后8 h脱险、12 Gy辐射8 h后脱险),每组10只。干预组动物先采用不同剂量γ射线外照射(4、6、12 Gy),再进行大深度快速上浮脱险实验(最大加压深度150 m),分析大鼠肺W/D、脾指数及血浆IL-1β的变化。结果: 与脱险对照组比较,核辐射后脱险大鼠的减压病发病率及死亡率明显上升。4 Gy、6 Gy照射4 h后上浮脱险的大鼠发病率和死亡率较照射8 h后高。12 Gy辐射后4 h及8 h脱险大鼠的减压病的发病率及死亡率均比低剂量照射组明显增高,死亡率尤其明显。和发病率及死亡率的变化相一致,肺组织湿/干比、肺组织病理损伤程度、脾指数下降也表现同样的变化趋势:较低剂量(4 Gy、6 Gy)辐射后4 h改变明显,8 h改变不明显,而高剂量(12 Gy)辐射后4、8 h均变化明显。和空白对照组及脱险对照组相比较,各辐射后脱险组的血浆IL-1β浓度均显著上升。结论: 核辐射引起放射性肺损伤、免疫功能下降及血浆炎症因子浓度升高,会增加大鼠快速上浮脱险致减压病的风险。     

The effect of combined application of quercetin and indralin on postradiation repair of the hematopoietic system in acute radiation sickness

Hybrid F1 mice (CBA × C57Bl/6) were subjected to irradiation at a nonlethal dose of 6.7 Gy that brought on acute radiation sickness. In the experiments performed, we observed the beneficial effect of combined application of quercetin injected 30–60 min prior to irradiation with γ rays and the emergent radioprotector indralin injected after irradiation on development of postradiation repair in hematopoietic tissue. This effect was expressed as accelerated formation of endogenous spleen colonies and recovery of spleen weight and attenuation of leucopenia 12 and 16 days after acute irradiation. Treatment with only quercetin was not radioprotective.     

Lipid peroxidation of rat spleen and thymus lymphocytes treated with x-rays (0-5-1.0 Gy)

It is established, that low doses of X-ray irradiation have affected activation of lipid peroxidation (LPO) in immunocompetent cells of the spleen and thymus. The amount of malonic dialdehyde (MDA) in lymphocytes of spleen and thymocytes increases 2 times twenty-four hours after animals' irradiation by X-rays in a dose of 0.5 Gy; when a dose grows to 1.0 Gy, the MDA content in the spleen lymphocytes increases from the 1st to the 6th days and in thymocytes from the 1st to the 3d days reaching its maximum at the 3d day. MDA accumulation in the immunocompetent cells of irradiated animals varies depending on the method of lipid peroxidation initiation.     

Early cell repair of the lung and the intestine in mice, after irradiation by fast neutrons and gamma rays

Lung tolerance is assessed from LD50 at 180 days after thoracic irradiation, in mice, with d(50) + Be neutrons and 60Co gamma rays. Early intestinal tolerance is assessed from LD50 at 7 days after abdominal irradiation. Additional dose (Dr) to reach LD50 when a single dose Ds is split into 2 equal fractions Di separated by different time intervals "i", is determined (Dr = 2Di - Ds), Dr is larger after gamma than after neutron irradiation, for lung and intestine. After thoracic irradiation with gamma rays, Dr reaches 3.36, 4.38, 5.12 and 5.37 Gy for "i" = 2, 6, 12 and 24 hours respectively; after neutron irradiation, Dr reaches 0.66, 0.9, 1.29, 1.95 and 1.50 Gy for "i" = 1, 2, 4, 12 and 24 hours. Dr is smaller for intestine; after abdominal irradiation with gamma rays, it reaches 1.99, 2.59, 2.74, 3.11, 3.34, 4.44 and 4.56 Gy for "i" = 1, 2, 3.5, 8, 12, 18 and 24 hours; after neutron irradiation, it reaches 0.13, 0.45, 0.42 and 1.33 Gy for "i" = 1.5, 3.5, 5.5 and 24 hours. After gamma irradiation, early repair is complete after 3.5 hours for intestine and needs 12 hours for lung.     

Organ-specific gene expressions in C57BL/6 mice after exposure to low-dose radiation

The possibility that radiation-induced alterations in gene expression are tissue specific and are related to apoptosis was examined using samples from brain, heart, lung, spleen and intestine from female C57BL6 mice after exposure to 0.2 Gy radiation. Apoptosis was the highest in spleen and intestine, moderate in lung, and absent in brain and heart. However, the mRNA expression of Trp53 and Cdkn1a (p21) after irradiation was not different among the organ types, and immunohistochemistry revealed that all the organs expressed these two proteins after irradiation. When expression patterns of 23 genes in the organs were examined by RT-PCR, neogenine, Apo1, nuclease sensitive element binding protein 1, syntaxin, cyclin G1, hNOP56, paraoxonase and glutathione peroxidase were overexpressed after irradiation in all the organs sampled, suggesting them as universal exposure markers for low-dose radiation. Sialyltransferase may be a candidate for radiation detection in spleen and intestine, which are radiosensitive organs. Because Sod1 (Cu/ZnSOD) and alphaB crystalline were expressed only in spleen, and protein tyrosine kinase and platelet membrane glycoprotein lib were expressed in both spleen and lung, these genes may also be potential markers for detection of radiation exposure, especially low-dose radiation, in these tissues. These data suggested possible tissue-specific markers of low-dose radiation exposure and suggested potential novel genetic modifiers of radiation response.     

Increased SOD activities and decreased lipid peroxide levels induced by low dose X irradiation in rat organs

After a single exposure to doses ranging from 0.05 to 0.50 Gy, the SOD activities in immune organs of the irradiated rats, at 4 h after whole-body X irradiation, showed significant increases by 50 to 90% (hereinafter p less than 0.05) in comparison with the control groups. The dose in the brain and liver showed tendencies to increase by 30 to 50% for doses ranging from 0.50 to 2.50 Gy. The levels of TBARS (lipid peroxides) in immune organs decreased significantly by 20 to 50% in contrast with the control groups for doses ranging from 0.10 to 1.00 Gy. Decreases by 20 to 30% were observed in brains and livers for doses near 0.50 Gy. When the dose was 0.25 Gy, the SOD activities in the spleen showed a persistent radiation-induced increase for at least 12 weeks, livers for 8 weeks, brains and thymuses for 4 weeks, and bone marrows for about 1 week. The TBARS levels in the brain and thymus showed persistent decreases due to irradiation for at least 12 weeks, and those in bone marrows for 8 h.     

X-irradiation effects on thymidine kinase (TK): I. TK1 and 2 in normal and malignant cells

Abstract. The effect of radiation on TK is more complicated than would be expected from earlier results on bone marrow cells ( Feinendegen et al. 1984 , Int. J. Radiat. Biol. 45, 205). TK activity increased at 0.01 Gy and then decreased up to 1 Gy in mouse spleen. In contrast to the results for the spleen, an increase in activity at 0.1 Gy was seen in mouse thymus. The activity of dephosphorylated TK1 (TK1a) in both spleen and thymus was reduced to 50% after irradiation at 0.5–1 Gy. The degree of phosphorylation (TK1b/TK1a ratio) changed in spleen, but not in thymus. The activity of TK2 in mouse liver increased at 3 h after 5 Gy by about 60%. In mouse ascites tumour, a dose-independent (1–5 Gy) oscillating TK1 activity was found up to 24 h, especially for TK1a and TK1b. The amount of TK1 was unchanged up to 12 h, but decreased at 24 h. This suggests that the differences in the changes in the degree of phosphorylation of TK1 after irradiation among spleen, thymus and ascites tumour further underline the complexity of the response of TK1 activity to irradiation. The dramatic change in the activities of TK1a and TK1b may illustrate that both of them are more radiosensitive than TK-h, a variant with mixed TK1 and TK2 properties.     

Changes in the antigenic properties of proteins of laboratory mice during oxidative stress

Changes in the level of oxidative damage to proteins in CD1 outbred mice γ irradiated with a dose of 3 Gy have been studied. The changes were estimated from the amount of carbonyl groups (CG) in the proteins. It was found that two hours after exposure to γ radiation, the amount of CG in the cytoplasmic and nuclear fractions of the liver, heart, brain, and spleen sharply increased. Two months after irradiation, the level of CG in the cytoplasmic and nuclear subcellular fractions of the liver and brain decreased to the level of CG in the control animals, which were not exposed to radiation. In the subcellular fractions of the heart and spleen, the increase in the degree of damage was more significant and a high level of damage was observed even two months after irradiation. An enhancement of the antigenic properties of proteins from the liver, heart, and spleen in the postirradiation period was found. Spleen proteins were most immunogenic. A comparison of the antigenic properties of proteins isolated from the tissues 60 days after irradiation revealed a correlation between the level of oxidative damage and the immunogenicity of the total protein fraction.     

The cytokinesis-block micronucleus assay as a biological dosimeter in spleen and peripheral blood lymphocytes of the mouse following acute whole-body irradiation

To evaluate the application of the cytokinesis-block (CB) micronucleus (MN) assay as a biological dosimeter following in vivo exposure to ionising radiation we determined the micronucleus frequency in spleen and peripheral blood lymphocytes of the mouse, serially, for 14 days following acute whole-body irradiation. The baseline MN frequency of spleen lymphocytes (7.86 +/- 0.68, mean +/- 1 SD) was significantly (p less than 0.001) elevated when compared to that for peripheral blood lymphocytes (4.10 +/- 0.53). Immediately after irradiation there was a substantial dose-related increase in MN, but the MN frequencies in spleen lymphocytes (120.2 +/- 9.4 for 1 Gy; 409.5 +/- 38.4 for 2 Gy) were significantly (p less than 0.009) elevated compared to those in peripheral blood lymphocytes (78.0 +/- 7.0 for 1 Gy; 200.2 +/- 10.9 for 2 Gy). During the 14 days after irradiation, the MN frequency in spleen lymphocytes declined gradually to approximately half of the value observed immediately after irradiation. By contrast the MN frequency in peripheral blood lymphocytes increased during the week after irradiation, but ultimately MN frequencies in blood and spleen became approximately the same by day 14. Study of isolated murine lymphocytes irradiated in vitro showed that the number of MN generated by a given dose of radiation was approximately 2-3 times greater than the number generated by in vivo irradiation. These results suggest that measurement of MN in vivo after irradiation can be used as an in vivo dosimeter. However, precise dosimetry is probably affected by factors such as kinetic changes in different lymphocyte populations and possibly by in vivo factors which influence sensitivity of cells to radiation.     

The effect of irradiation on the antibody enhancing helper T cells

Helper T cells specific for sheep erythrocytes were generated in lethally irradiated mice. The helper effect exerted by these cells was determined in vitro in spleen cell cultures. Irradiation of the helper cells in vivo or in vitro with 1-9 Gy resulted in a bimodal relation between radiation dose and helper effect when measured either immediately or 6 hours after irradiation. The dose-effect curve became nearly linear when tested 20 hours after irradiation. These results indicated that the helper population consisted of about 80 per cent of cells inactivated shortly after irradiation, possibly due to interphase death, and a second type showing a more retarded cell death. The latter cells were able to exert a helper function during the interval between irradiation and cell death.     

γ射线对人淋巴细胞cx43和ANLN基因转录表达的影响

目的研究γ射线对人外周血淋巴细胞cx43和ANLN基因转录表达的影响。方法对数生长期的淋巴细胞,分别给予1、2、3、4、5、6 Gy的^60Coγ射线照射,照射后12h,以及2Gy照射后4、8、12、24、36、48、72h,分别提取总RNA,反转录成cDNA。利用实时荧光定量PCR技术,检测各组cx43和ANLN基因表达改变。结果人外周血淋巴细胞cx43 mRNA表达水平在2Gy照射后4、8、12h明显增高,分别为对照组（未照射组）的6．74、9．06、7．22倍（P〈0．05）;24～72h,其表达水平与对照组相比没有明显变化。1、2、3、4、5、6Gy剂量照射后12h,cx43 mRNA表达水平显著增高（P〈0．05）。ANLN mRoNA表达水平在2Gy不同时间点及1～5Gy照射后12h,表达降低（P〈0．05）,6Gy照射后12h其表达开始升高,为对照组的6．08倍（P〈0．05）。结论γ射线照射2Gy不同时间点及不同剂量照射后12h,cx43基因表达上调,ANLN基因表达下调。1～3Gy剂量照射后12h,cx43 mRNA表达在此范围内有时间和剂量的依赖性。cx43可能会发展为核事故受照射人员的分子生物学剂量标记物。     

Effect of alanyl-glutamine on leucine and protein metabolism in irradiated rats

Summary. The mechanism by which glutamine produces a favorable effect in the treatment of sepsis, injury, burns and abdominal irradiation is not completely understood. The main aim of this study was to evaluate the effect of alanyl-glutamine (AlaGln) administration on the metabolism of proteins in irradiated rats. The rats were exposed to whole-body irradiation (8 Gy) and then fed intragastrically with a mixture of glucose and amino acids either with AlaGln or without AlaGln. At 48 hours after irradiation, parameters of whole-body protein metabolism and DNA synthesis in intestinal mucosa were investigated using a primed, continuous infusion of [1-¹⁴C]leucine and [³H]thymidine. In addition, we evaluated the effect of irradiation and AlaGln on gut morphology, blood count and amino acid concentrations in blood plasma and skeletal muscle. Control rats were not irradiated but were given identical treatment. An increase in whole-body leucine oxidation, and insignificant changes in whole-body proteolysis and in protein synthesis were observed after irradiation. In irradiated rats we observed a decrease in muscle glutamine concentration, a decrease in protein synthesis in jejunum, colon and heart, and an increase in synthesis of proteins of blood plasma and spleen. Morphological examination and measurement of DNA synthesis failed to demonstrate any favorable effect of AlaGln supplementation on irradiated gut. However, administration of AlaGln resulted in a decrease in whole-body proteolysis and leucine oxidation which caused an increase in the fraction of leucine incorporated into the pool of body proteins. We conclude that the data obtained demonstrate that irradiation induces metabolic derangement associated with increased oxidation of essential branched-chain amino acids (valine, leucine and isoleucine) and that these disturbances can be ameliorated by administration of AlaGln. Received February 14, 2000 Accepted July 12, 2000     

Possible biomarkers for ionizing radiation exposure in human peripheral blood lymphocytes

Biomarkers to indicate past exposure to radiation have not been entirely satisfactory. Using cDNA microarray hybridization to find new potential biomarkers, we identified highly expressed genes in human peripheral blood lymphocytes (PBLs) after irradiation 1 Gy ex vivo. The present set of radiation markers in PBLs was identified 12 h after radiation. A total of 44 genes were identified. However, when RT-PCR was performed with mRNA from the PBLs of five individuals, only four genes, including TRAIL receptor 2, DRAL (now known as FHL2), cyclin G, and cyclin protein gene, showed greater than 50% agreement between gene induction as detected by microarray analysis and by RT-PCR. When more than 32 donors were tested for the above four genes, greater than 85% agreement was obtained between gene induction measured by microarray analysis and by RT-PCR. There was a linear dose-response relationship between 0.5 and 4 Gy 12 h after irradiation; however, there was less linearity at later times. These results suggested that the relative expression levels of genes such as TRAIL receptor 2, FHL2, cyclin G, and cyclin protein gene in PBLs may provide estimates of radiation exposures.     

CFU-S and haematopoietic microenvironment in mice after fractionated irradiation. A study on spleen colonies.

The paper is aimed at evaluating the quantity and quality of the haematopoietic stem cells, CFU-S, in the bone marrow and the functional effectiveness of the haematopoietic microenvironment of the spleen in two time intervals after repeated exposure of mice to doses of 0.5 Gy gamma-rays once a week (total doses of 12 and 24 Gy). After irradiation, bone marrow was cross-transplanted between fractionatedly irradiated and control mice. The parameter evaluated were numbers of spleen colonies classified into size categories. The data obtained provide evidence for a significant damage to the CFU-S, concerning both their number and proliferation ability, after both total doses used. The functional effectiveness of the haematopoietic microenvironment of the spleen was impaired only in bone marrow recipients receiving a transplant after having been exposed to a total dose of 24 Gy; this dose combined with subsequent pre-transplantation irradiation resulted in a marked suppression of cell production within the spleen colonies formed from a normal bone marrow on the spleens of fractionatedly irradiated mice.     

Characterization of altered absorptive and secretory functions in the rat colon after abdominal irradiation: comparison with the effects of total-body irradiation.

The aim of this work was to determine the alterations in the absorptive and secretory functions of the rat colon after abdominal irradiation and to compare the effects of abdominal and whole-body irradiation. Rats received an abdominal irradiation with 8 to 12 Gy and were studied at 1, 4 and 7 days after exposure. Water and electrolyte absorption was measured in vivo by insertion of an agarose cylinder into the colons of anesthetized rats. In vitro measurements of potential difference, short-circuit current and tissue conductance were performed in Ussing chambers under basal and agonist-stimulated conditions. Most of the changes appeared at 4 days after abdominal irradiation. At this time, a decrease in water and electrolyte absorption in the colon was observed for radiation doses > or = 9 Gy. The response to secretagogues (VIP, 5-HT and forskolin) was attenuated after 10 and 12 Gy. Epithelial integrity, estimated by potential difference and tissue conductance, was altered from 1 to 7 days after 12 Gy abdominal irradiation. These results show that the function of the colon was affected by abdominal irradiation. Comparison with earlier results for total-body irradiation demonstrated a difference of 2 Gy in the radiation dose needed to induce changes in the function of the colon.     

Low-dose total-body γ irradiation modulates immune response to acute proton radiation

Health risks due to exposure to low-dose/low-dose-rate radiation alone or when combined with acute irradiation are not yet clearly defined. This study quantified the effects of protracted exposure to low-dose/low-dose-rate γ rays with and without acute exposure to protons on the response of immune and other cell populations. C57BL/6 mice were irradiated with ??Co (0.05 Gy at 0.025 cGy/h); subsets were subsequently exposed to high-dose/high-dose-rate proton radiation (250 MeV; 2 or 3 Gy at 0.5 Gy/min). Analyses were performed at 4 and 17 days postexposure. Spleen and thymus masses relative to body mass were decreased on day 4 after proton irradiation with or without pre-exposure to γ rays; by day 17, however, the decrease was attenuated by the priming dose. Proton dose-dependent decreases, either with or without pre-exposure to γ rays, occurred in white blood cell, lymphocyte and granulocyte counts in blood but not in spleen. A similar pattern was found for lymphocyte subpopulations, including CD3+ T, CD19+ B, CD4+ T, CD8+ T and NK1.1+ natural killer (NK) cells. Spontaneous DNA synthesis by leukocytes after proton irradiation was high in blood on day 4 and high in spleen on day 17; priming with γ radiation attenuated the effect of 3 Gy in both body compartments. Some differences were also noted among groups in erythrocyte and thrombocyte characteristics. Analysis of splenocytes activated with anti-CD3/anti-CD28 antibodies showed changes in T-helper 1 (Th1) and Th2 cytokines. Overall, the data demonstrate that pre-exposure of an intact mammal to low-dose/low-dose-rate γ rays can attenuate the response to acute exposure to proton radiation with respect to at least some cell populations.     

Effect of natural and postradiation volatile secretions of mice on the immune reactivity and blood cellularity of irradiated animals

It has been shown that natural and postradiation volatile urinary secretions of mice can remotely restore the immune reactivity and blood indices reduced as a result of exposure of laboratory mice to ionizing radiation. Antibody formation in spleen of gamma-irradiated (1 Gy) CBA strain mice was increased after exposure of both syngeneic and allogeneic animals with urine volatile secretions. Volatile natural secretions of intact mice have a more pronounced antibody stimulating activity than volatile secretions from animals exposed to gamma-radiation. Immunoreactivity ofy-irradiated C57B16 strain mice with low olfactory reactivity increases only after their exposure with volatile secretions of intact syngeneic animals. The total number of leukocytes and lymphocytes in the peripheral blood of gamma-irradiated (1 Gy) inbred mice increases after exposure with secretions obtained from them before irradiation. The role of hemo-signalling in the selective stimulation of immunity and blood content in conditions of radiation damage is discussed.     

The effect of diucifon on the hematopoietic and immune systems in normal and irradiated organisms

It was shown that irradiation of mice with the dose of 4 Gy affected the immune and haemopoietic systems. Diucyphone injected on days 6-8 after irradiation favoured the production of antibodies in the spleen, increased the yield of exogenous splenic colonies and corrected differentiation of the haemopoietic stem cells. In the normal body, diucyphone decreased the colony-forming activity and did not change the haemopoietic stem cell differentiation.     

Effect of radiation-induced bystander chemosignals of mice on the humoral immune response in spleen and lymph nodes of intact recipients

The ability of post-radiation (4 Gy) bystander chemosignals (the volatile components of mouse urine) to distantly modulate the humoral immune response to the sheep red blood cells in the spleen and popliteal lymph nodes of intact recipients has been investigated. It was shown that the exposure of animals to chemosignals before antigen injection resulted in the decrease and increase of the immune response in the spleen and lymph nodes, respectively. When animals were exposed to chemosignals after the antigenic stimulus, an increased immune response was observed in both spleen and lymph nodes. The contribution of radiation-induced bystander signaling in the response of socially organized animals to the effect of ionizing irradiation is discussed.