巴西莓和诺尼果粉对C57BL/6J小鼠抗8Gy 剂量辐射的初步研究

目的:比较研究巴西莓果粉Herbal Clean Energy和诺尼果粉Noni GIA通过消除自由基、降低造血细胞凋亡等作用对8Gy大剂量γ线照射后小鼠活存的影响。方法:将C57BL/6J小鼠随机分组、每组雌雄各半,单一果粉在相同灌胃剂量下采用照前灌胃10天、照后灌胃10天以及照前照后灌胃10天三种灌胃方式,首先观察了小鼠在用钴60γ线8Gy致死剂量照后40天活存率;其次在上述相同条件处理下,照后10天对小鼠外周血白细胞计数、CD4+和CD8+淋巴细胞类型、活性氧、骨髓造血细胞凋亡率等分析。结果:生理盐水灌胃组C57BL/6J小鼠受8Gy照射在第18天全部死亡(n=20,下同),死亡率100%,而照前10天灌胃后照射8Gy试验组:巴西莓和诺尼果粉组照后40天活存10/20只,诺尼果粉组第40天活存9/20,巴西莓果粉组第40天活存8/20。在照后灌胃的组别中,诺尼果粉组第40天活存7/20,巴西莓和诺尼果粉组第40天活存4/20只,巴西莓果粉组第40天活存2/20。照射前后单独或联合灌胃两种果粉组外周血白细胞均有升高,而骨髓造血细胞凋亡降低,而且果粉灌胃小鼠外周血Th/Tc比率同对照组相比明显保持于正常值范围。红细胞和血小板数据无明显变化,活性氧含量则呈现无规律表现。结论:巴西莓和诺尼果粉对小鼠抗辐射有预防作用,其细胞学表现为保持造血增殖能力、降低造血细胞凋亡,并维持Th/Tc免疫平衡;显示果粉对保持造血和免疫能力是提高抵抗辐射损伤、提高活存的基础。同时表明,服用巴西莓果粉和诺尼果粉,对人体防止辐射损伤有预防作用。     

唐古特大黄多糖组分1对辐射损伤所致肠上皮细胞凋亡的保护作用及其可能的机制

目的:探讨唐古特大黄多糖(Rheum tanguticum polysaceharide,RTP)组分1(RTP1)对60yCo射线诱导的肠上皮细胞IEC-6凋亡的保护作用及其可能的机制.方法:采用大鼠空肠上皮细胞(IEC-6细胞株),共分为4组,正常对照组(Normal Control,NC)、辐射对照组(Irradiation Control,Ic)以及RTP1低剂量组(10 μg/m1)、中剂量组(30 μg/m1)和高剂量组(100 μg/ml),以6.0 Gy60Coγ射线一次性照射损伤细胞,损伤前用RTP1预处理细胞48 h.采用MTT比色法测定细胞活力,吖啶橙荧光染色及流式细胞仪检测细胞凋亡的发生,Western blot测定Caspase-3酶活性.结果:6.0 Gy60Coγ射线照射可明显降低细胞存活率并诱导细胞凋亡,凋亡率为31.3％,细胞Caspase-3的活性明显升高,RTP1预处理细胞可明显提高细胞存活率,流式细胞仪检测凋亡率(30、100μg/ml)分别降低至24.4％和21.5％,Caspase-3酶活性降低,并呈现一定的剂量依赖性.结论:RTP1可明显抑制60γCo射线诱导的IEC-6细胞凋亡,其细胞保护作用可能与抑制Caspase-3活性相关.     

三种小鼠骨髓细胞辐射抗性的比较

目的对IRM-2、ICR及615小鼠骨髓细胞体外照射后细胞损伤进行比较研究,探讨IRM-2小鼠的抗辐射损伤机制。方法用常规法进行外周血白细胞和骨髓有核细胞计数;应用化学发光法检测不同剂量γ射线对小鼠骨髓细胞活力的影响;用PA法（FITC-Annexin V和PI标记法）检测骨髓细胞凋亡。结果IRM-2小鼠骨髓细胞和外周血白细胞计数高于ICR、615小鼠,经统计学处理后差异有显著性（P〈0.01）。经1 Gy、4 Gy照射后6 h,IRM-2、ICR、615小鼠骨髓细胞相对活力分别为86.6%和79.3%,77.5%和70.4%,77.4%和68.7%,IRM-2小鼠与ICR、615小鼠比较,细胞活力有所提高,IRM-2小鼠骨髓造血细胞死亡率及凋亡率低于ICR及615小鼠。结论IRM-2小鼠有较强的免疫及造血功能,骨髓造血细胞凋亡率低于ICR及615小鼠,其抗辐射机制仍需进一步研究。     

PER1对人肝癌细胞BEL-7402辐射敏感性的影响

本文通过X射线照射SMMC-7721、BEL-7402和HepG2三种肝癌细胞后,以克隆形成试验检测其存活分数,结果显示在梯度剂量X射线0、2、4、6、8、10 Gy照射下SMMC-7721、BEL-7402、HepG2三种细胞克隆存活分数逐渐下降,其中SMMC-7721在三种肝癌细胞系中对辐射最敏感,BEL-7402辐射抗性在三种肝癌细胞系中最高。Western blot检测发现PER1在SMMC-7721中的表达水平明显显著高于BEL-7402和HepG2(P<0.05)。过表达PER1蛋白以后,BEL-7402接受5 Gy X射线照射后凋亡明显增多,同时,western blot和RT-qPCR试验结果发现,X射线照射过表达PER1的BEL-7402细胞,抗凋亡蛋白Bcl-2表达明显降低,凋亡执行蛋白Caspase-3断裂明显增多。研究结果表明PER1蛋白的高水平表达可以促进X射线诱导的凋亡,增强肝癌细胞的辐射敏感性。     

PI3K激活NF-κB信号通路保护中子辐射致IEC-6细胞损伤

中子属于高传能线密度电离辐射,能产生比κ射线更为严重的放射损伤,肠上皮对中子辐射高度敏感,迄今未见有关中子辐射致肠上皮细胞损伤中PI3K对NF-κB信号通路调控的研究报道.本研究旨在探讨中子照射后肠上皮细胞中PI3K对NF-κB信号通路的调控及其在中子辐射致肠上皮细胞损伤中的作用.选取肠上皮细胞系-6（intestinal epithelial cell No.6,IEC-6）进行传代培养,随机分为对照组、4Gy中子照射组和4Gy中子照射＋LY294002处理组,照射组和LY294002处理组细胞采用4Gy中子均匀照射,LY294002处理组细胞在照前24h给予终浓度为10κmol/L的LY294002,各组于照射后6和24h采用MTT比色法、流式细胞术和免疫印迹（Western blot）方法检测IEC-6细胞增殖活力、凋亡与坏死率以及NF-κB信号通路相关分子NF-κB（p65）,IKKκ和IκBκ的表达变化.研究发现,4Gy中子照射后6和24h,IEC-6细胞增殖活力下降,凋亡和坏死率增加;应用LY294002后IEC-6细胞增殖活力较照射组明显下降,IEC-6细胞凋亡和坏死率较照射组增加.4Gy中子照射后6和24h,IEC-6细胞NF-κB（p65）和IKKκ表达升高,IκBκ表达降低;应用LY294002后NF-κB（p65）和IKKκ表达降低,IκBκ表达升高,表明4Gy中子照射可引起IEC-6细胞增殖活力下降,凋亡和坏死率增加;PI3K可激活NF-κB信号通路,对中子辐射IEC-6细胞损伤发挥保护作用.     

p18INK4C基因缺失增强造血干细胞在亚致死剂量照射小鼠体内长期植入能力

观察p18INK4C(p18)基因缺失对造血干细胞(HSC)在亚致死剂量照射小鼠体内长期植入的影响. 供体为p18基因缺失型(p18(/()纯系C57BL/6小鼠(CD45.2表型), 竞争性细胞来源于C57BL/6-Ly5.1(CD45.1/2)双表型小鼠, 受体为野生型(p18+/+)C57BL/6-Ly5.1(CD45.1)小鼠. 竞争性骨髓移植(cBMT)实验根据受体小鼠照射剂量的不同分为3个剂量组(10 Gy, 5 Gy和1 Gy). 供体细胞和竞争性细胞1:1混合后移植, 移植后采集外周血和骨髓细胞用流式细胞仪检测各细胞比例. 造血恢复移植实验: 移植后检测外周血白细胞计数评价移植后造血恢复速度. 10和5 Gy照射剂量组, 供体细胞和竞争性细胞成功植入, 而1 Gy照射剂量组无供体细胞植入. 无论在10 Gy或是5 Gy照射剂量情况下, 供体细胞在受体内的比例均高于竞争性细胞. 移植后6周, 10和5 Gy照射剂量时外周血中供体细胞比例分别为竞争性细胞的1.46±0.21倍和1.64±0.43倍, 14周时分别为竞争性细胞的1.84±0.25倍和2.00±0.49倍, 26周时分别为竞争性细胞的3.13±0.79倍和3.24±1.33倍. 移植后6个月, 10 Gy照射剂量时骨髓细胞中供体细胞比例为竞争性细胞的7.68±4.42倍, 5 Gy照射剂量时为竞争性细胞的10.83±2.98倍. 移植后6个月, 在10和5 Gy照射剂量组之间骨髓中造血细胞植入率相当, 分别为(85.53±8.71)%和(80.87±2.87)% (P = 0.457). p18(/(细胞与p18+/+细胞相比, 移植后造血恢复的速度相当. p18基因缺失可以显著增强HSC在亚致死剂量照射小鼠体内的长期植入能力.     

骨髓基质细胞的辐射效应及其临床意义

小鼠骨髓基质细胞团在γ线照射后的Do值为2.40Gy,但其成灶能力损伤后持续时间较久。正常骨髓基质细胞能促进骨髓GM-CFU-C的生长;照射10-80Gy后的骨髓基质细胞失去这种促进作用。文中讨论了骨髓基质细胞的辐射效应及其临床意义,提出了谨慎选择放射治疗剂量的必要性。     

小剂量16O8+离子预辐射减轻大剂量辐射所致小鼠睾丸组织损伤

为了了解小剂量重离子辐射诱导小鼠睾丸结构的适应性反应,采用小剂量(0.05Gy)~(16)O~(8 )离子照射B6C3F_1雄性小鼠睾丸。4h后,再给予2Gy~(16)O~(8 )离子照射。照射后第35天取材在光镜下观察睾丸结构。结果显示,大剂量(2Gy)照射明显损伤睾丸组织,主要表现为曲精细管直径几乎减小一半,精管内各发育阶段的生殖细胞减少或消失,特别是精原细胞几乎完全消失。而Leydig细胞和Sertoli细胞仅有轻度核固缩及胞浆减少。提示睾丸生殖细胞的辐射敏感性明显高于其间质组织细胞。预先给予小剂量(0.05Gy)照射可明显减轻随后大剂量(2Gy)辐射对睾丸组织的损伤。提示小剂量重离子辐射可诱导小鼠睾丸结构明显的适应性反应。     

X线全身照射对2型糖尿病KKAy小鼠造血免疫系统功能的影响

目的观察X线全身照射对2型糖尿病模型KKAy小鼠的造血免疫系统功能的损伤作用,并与对照C57小鼠进行比较。方法KKAy小鼠,分为对照组和照射组,照射组小鼠经X线全身照射,剂量4Gy,C57小鼠作为对照。照射后15d检测小鼠的外周血常规,流式细胞术检测骨髓中造血祖细胞、造血干细胞和长期造血干细胞的比例,脾中B细胞和T细胞的比例,胸腺中CD4CD8双阳性T细胞、CD4单阳性T细胞和CD8单阳性T细胞的比例。通过粒细胞集落形成能力实验评价小鼠造血祖细胞的功能。结果照射前KKAy小鼠的HSC和LT-HSC的比例低于C57小鼠。4Gy全身照射后,KKAy小鼠的外周血WBC、RBC、PLT、HGB和LYM%分别下降了68.42%、12.17%、8.78%、30.12%、70.84%;骨髓中HPC、HSC和LT-HSC的比例分别下降了34.02%、29.49%、35.74%;脾B细胞和T细胞的比例分别下降了57.85%、58.81%;胸腺CD4CD8双阳性细胞的比例下降了51.70%。KKAy小鼠的骨髓HSC、LT-HSC、外周血RBC和HGB的降低幅度显著低于C57小鼠。结论4Gy全身照射损伤KKAy小鼠的造血免疫系统功能,KKAy小鼠可能比C57小鼠表现出对电离辐射较强的耐受性。     

p18INK4C基因缺失增强造血干细胞在亚致死剂量

观察p18^INK4C (p18)基因缺失对造血干细胞(HSC)在亚致死剂量照射小鼠体内长期植入的影响. 供体为p18基因缺失型(p18^-/-)纯系C57BL/6小鼠(CD45.2表型), 竞争性细胞来源于C57BL/6-Ly5.1(CD45.1/2)双表型小鼠, 受体为野生型(p18^+/+)C57BL/6-Ly5.1(CD45.1)小鼠. 竞争性骨髓移植(cBMT)实验根据受体小鼠照射剂量的不同分为3个剂量组(10 Gy, 5 Gy和1 Gy). 供体细胞和竞争性细胞1:1混合后移植, 移植后采集外周血和骨髓细胞用流式细胞仪检测各细胞比例. 造血恢复移植实验: 移植后检测外周血白细胞计数评价移植后造血恢复速度. 10和5 Gy照射剂量组, 供体细胞和竞争性细胞成功植入, 而1 Gy照射剂量组无供体细胞植入. 无论在10 Gy或是5 Gy照射剂量情况下, 供体细胞在受体内的比例均高于竞争性细胞. 移植后6周, 10和5 Gy照射剂量时外周血中供体细胞比例分别为竞争性细胞的1.46±0.21倍和1.64±0.43倍, 14周时分别为竞争性细胞的1.84±0.25倍和2.00±0.49倍, 26周时分别为竞争性细胞的3.13±0.79倍和3.24±1.33倍. 移植后6个月, 10 Gy照射剂量时骨髓细胞中供体细胞比例为竞争性细胞的7.68±4.42倍, 5 Gy照射剂量时为竞争性细胞的10.83±2.98倍. 移植后6个月, 在10和5 Gy照射剂量组之间骨髓中造血细胞植入率相当, 分别为(85.53±8.71)%和(80.87±2.87)% (P = 0.457). p18^-/-细胞与p18^+/+细胞相比, 移植后造血恢复的速度相当. p18基因缺失可以显著增强HSC在亚致死剂量照射小鼠体内的长期植入能力.     

Bystander apoptosis in human cells mediated by irradiated blood plasma

Following exposure to high doses of ionizing radiation, due to an accident or during radiotherapy, bystander signalling poses a potential hazard to unirradiated cells and tissues. This process can be mediated by factors circulating in blood plasma. Thus, we assessed the ability of plasma taken from in vitro irradiated human blood to produce a direct cytotoxic effect, by inducing apoptosis in primary human peripheral blood mononuclear cells (PBM), which mainly comprised G(0)-stage lymphocytes. Plasma was collected from healthy donors' blood irradiated in vitro to 0-40Gy acute γ-rays. Reporter PBM were separated from unirradiated blood with Histopaque and held in medium with the test plasma for 24h at 37°C. Additionally, plasma from in vitro irradiated and unirradiated blood was tested against PBM collected from blood given 4Gy. Apoptosis in reporter PBM was measured by the Annexin V test using flow cytometry. Plasma collected from unirradiated and irradiated blood did not produce any apoptotic response above the control level in unirradiated reporter PBM. Surprisingly, plasma from irradiated blood caused a dose-dependent reduction of apoptosis in irradiated reporter PBM. The yields of radiation-induced cell death in irradiated reporter PBM (after subtracting the respective values in unirradiated reporter PBM) were 22.2±1.8% in plasma-free cultures, 21.6±1.1% in cultures treated with plasma from unirradiated blood, 20.2±1.4% in cultures with plasma from blood given 2-4Gy and 16.7±3.2% in cultures with plasma from blood given 6-10Gy. These results suggested that irradiated blood plasma did not cause a radiation-induced bystander cell-killing effect. Instead, a reduction of apoptosis in irradiated reporter cells cultured with irradiated blood plasma has implications concerning oncogenic risk from mutated cells surviving after high dose in vivo irradiation (e.g. radiotherapy) and requires further study.     

Protection from radiation-induced apoptosis by the radioprotector amifostine (WR-2721) is radiation dose dependent

The radioprotective agent amifostine is a free radical scavenger that can protect cells from the damaging effects of ionising radiation when administered prior to radiation exposure. However, amifostine has also been shown to protect cells from chromosomal mutations when administered after radiation exposure. As apoptosis is a common mechanism by which cells with mutations are removed from the cell population, we investigated whether amifostine stimulates apoptosis when administered after radiation exposure. We chose to study a relatively low dose which is the maximum radiation dose for radiation emergency workers (0.25 Gy) and a high dose relevant to radiotherapy exposures (6 Gy). Mice were administered 400 mg/kg amifostine 30 min before, or 3 h after, whole-body irradiation with 0.25 or 6 Gy X-rays and apoptosis was analysed 3 or 7 h later in spleen and bone marrow. We observed a significant increase in radiation-induced apoptosis in the spleen of mice when amifostine was administered before or after 0.25 Gy X-rays. In contrast, when a high dose of radiation was used (6 Gy), amifostine caused a reduction in radiation-induced apoptosis 3 h post-irradiation in spleen and bone marrow similar to previously published studies. This is the first study to investigate the effect of amifostine on radiation-induced apoptosis at a relatively low radiation dose and the first to demonstrate that while amifostine can reduce apoptosis from high doses of radiation, it does not mediate the same effect in response to low-dose exposures. These results suggest that there may be a dose threshold at which amifostine protects from radiation-induced apoptosis and highlight the importance of examining a range of radiation doses and timepoints.     

Anti-apoptotic peptides protect against radiation-induced cell death

The risk of terrorist attacks utilizing either nuclear or radiological weapons has raised concerns about the current lack of effective radioprotectants. Here it is demonstrated that the BH4 peptide domain of the anti-apoptotic protein Bcl-xL can be delivered to cells by covalent attachment to the TAT peptide transduction domain (TAT-BH4) and provide protection in vitro and in vivo from radiation-induced apoptotic cell death. Isolated human lymphocytes treated with TAT-BH4 were protected against apoptosis following exposure to 15Gy radiation. In mice exposed to 5Gy radiation, TAT-BH4 treatment protected splenocytes and thymocytes from radiation-induced apoptotic cell death. Most importantly, in vivo radiation protection was observed in mice whether TAT-BH4 treatment was given prior to or after irradiation. Thus, by targeting steps within the apoptosis signaling pathway it is possible to develop post-exposure treatments to protect radio-sensitive tissues.     

Computerized video time-lapse microscopy studies of ionizing radiation-induced rapid-interphase and mitosis-related apoptosis in lymphoid cells

Computerized video time-lapse (CVTL) microscopy of X-irradiated cultures of cells of the murine lymphoma cell lines ST4 and L5178Y-S and the human lymphoid cell line MOLT-4 demonstrated that these cells exhibit a wide disparity in the timing of induction and execution of radiation-induced cell death that included rapid-interphase apoptosis, delayed apoptosis, and postmitotic apoptosis. ST4 cells that received 2.5 or 4 Gy of X radiation underwent rapid-interphase apoptosis within 2 h. Apoptosis commenced with a 10-20-min burst of membrane blebbing followed by swelling for 2-4 h and cell collapse. No apoptotic bodies were formed. After a dose of 1 Gy, approximately 90% of ST4 cells died by rapid-interphase apoptosis, while the remainder completed several rounds of cell division prior to cell death. Postmitotic death of ST4 cells occurred with the same morphological sequence of events as during rapid-interphase apoptosis induced by doses of 1-4 Gy. In contrast, L5178Y-S and MOLT-4 cells that received 4 Gy underwent apoptosis more slowly, with a complex series of events occurring over 30-60 h. Only 3% of L5178Y-S cells and 24% of MOLT-4 cells underwent apoptosis without attempting cell division. The cells became abnormally large during a long G(2)-phase delay, and then most of the cells (76-97%) attempted to divide for the first or second time at approximately 18-30 h postirradiation. However, either mitosis failed or division was aberrant; i.e., the large cells divided into three or four fragments which eventually fused together. This process was followed by several rounds of complex and unpredictable membrane blebbing, gross distortions of shape, fragmentation-refusion events, and formation of apoptotic bodies, after which the cells collapsed at 36-60 h postirradiation.     

Ascorbic acid inhibits apoptosis induced by X irradiation in HL60 myeloid leukemia cells.

Exposure of cells to ionizing radiation can cause apoptosis. Since antioxidants have been shown to protect against radiation-induced apoptosis, in this study we have evaluated the putative protective effect of ascorbate against radiation-induced apoptosis as well as the production of peroxides in the cells. HL60 cells transport the oxidized form of ascorbic acid, dehydroascorbic acid (DHA), and accumulate reduced ascorbate. Exposure of the cells to 5-40 Gy X radiation resulted in induction of apoptosis. Preincubation of the cells with DHA reduced the level of apoptosis after exposure to 5-20 Gy. Exposure of the cells to 5 or 20 Gy X radiation did not affect the intracellular concentration of peroxides, while phorbol myristate acetate (PMA), which is known to induce production of H(2)O(2) in cells (and served as a control), resulted in an increase in peroxides and a decrease in intracellular ascorbate. Irradiation of the cells with 1-3 Gy resulted in up-regulation of expression of BCL2 without affecting the level of apoptosis. At higher doses of radiation, enhanced BCL2 expression did not prevent radiation-induced apoptosis. Loading of the cells with ascorbate prior to their exposure to 1-3 Gy X radiation did not affect the enhanced BCL2 expression observed in the irradiated cells. At higher doses of radiation, ascorbate decreased apoptosis and restored the level of BCL2 in the cells. Exposure of the cells to 3-20 Gy X radiation enhanced the cell surface expression of TNFRSF6 (formerly known as Fas/APO-1) antigen and enhanced anti-TNFRSF6 antibody-induced apoptosis of the cells. Ascorbate loading did not affect expression of TNFRSF6 and did not overcome the anti-TNFRSF6 antibody-induced apoptosis. In conclusion, our data demonstrate that exposure of HL60 cells to radiation enhanced BCL2 and TNFRSF6 expression. Ascorbate did not affect BCL2 or TNFRSF6 expression. We therefore conclude that it protects HL60 cells against radiation-induced apoptosis, although the mechanisms of protection must still be elucidated.     

Retinoids and TIMP1 prevent radiation-induced apoptosis of capillary endothelial cells

Radiation-induced changes in capillaries constitute a basic injury in the pathogenesis of chronic radiation damage to the heart, lung, liver, kidney and brain. It is important to identify new radioprotectors for capillary endothelial cells for use during radiotherapy to minimize normal tissue damage and possibly to increase the deliverable dose. Previously we demonstrated that exposure to ionizing radiation (10 Gy) results in death of bovine adrenal capillary endothelial cells in confluent monolayers by apoptosis. We also showed that retinoids inhibit the growth of endothelial cells, induce their differentiation, down-regulate matrix metalloproteinase (MMP) production, and up-regulate tissue inhibitors of matrix metalloproteinases (TIMPs). In the present studies, we demonstrated that radiation (10 Gy) induced an immediate increase in the amounts and activation of MMP1 and MMP2 in the cell fraction and medium of bovine capillary endothelial cells followed by an incidence of apoptosis. We also obtained data indicating that radiation-induced apoptosis can be inhibited by exposing bovine capillary endothelial cells to all-trans-retinol or all-trans-retinoic acid for 6 days before irradiation, even when the vitamins were removed 24 h before irradiation. Finally, we determined that inhibition of MMPs by TIMP was sufficient to block radiation-induced apoptosis, suggesting that the mechanism of protection by retinoids is through the alteration of levels of MMPs and TIMPs produced by the cells.     

Hyaluronic acid is radioprotective in the intestine through a TLR4 and COX-2-mediated mechanism

The intestinal epithelium is sensitive to radiation injury. Damage to the intestinal epithelium is dose limiting in radiation therapy of abdominal cancers. There is a need for agents that can be given before radiation therapy to protect the intestinal epithelium. C57BL6 mice were subjected to 12 Gy of total body radiation. Some mice received intraperitoneal hyaluronic acid (HA) before radiation. Mice were killed 6 h after radiation to assess radiation-induced apoptosis in the intestine; other mice were killed at 84 h to assess crypt survival. Total body radiation (12 Gy) resulted in increased expression of HA synthases and HA in the intestine and increased plasma HA (5-fold). Intraperitoneal injection of HA (30 mg/kg) before radiation resulted in a 1.8-fold increase in intestinal crypt survival and a decrease in radiation-induced apoptosis. The radioprotective effects of HA were not seen in Toll-like receptor 4 (TLR4)- or cyclooxygenase-2 (COX-2)-deficient mice. Intraperitoneal injection of HA induced a 1.5-fold increase in intestinal COX-2 expression, a 1.5-fold increase in intestinal PGE?, and the migration of COX-2-expressing mesenchymal stem cells from the lamina propria in the villi to the lamina propria near the crypt. We conclude that 1) radiation induces increased HA expression through inducing HA synthases, 2) intraperitoneal HA given before radiation reduces radiation-induced apoptosis and increases crypt survival, and 3) these radioprotective effects are mediated through TLR4, COX-2, and the migration of COX-2-expressing mesenchymal stem cells.     

Modulation of gamma-ray-induced apoptosis in human peripheral blood leukocytes by famotidine and vitamin C

To study the radioprotective effects of vitamin C and famotidine against radiation-induced apoptosis in human peripheral blood leukocytes, peripheral blood was obtained from six healthy volunteers including three males and three females. Twelve microlitres of blood sample diluted in 1 ml complete RPMI-1640 medium was irradiated with various doses of gamma-rays (4, 8 and 12 Gy) in the presence or absence of various doses of vitamin C and famotidine. After 48 and 72 h incubation in a 37 degrees C CO(2) incubator, neutral comet assay was performed for all samples. At least 1000 cells were analyzed for each sample for presence of apoptosis. Data were statistically evaluated using Mann-Whitney non-parametric and ANOVA tests. Results show a significant increase in apoptosis induction following gamma-irradiation with a dose dependent manner compared to controls (p<0.001). Presence of famotidine at 200 microg/ml produced a significant protective effect against radiation-induced apoptosis for various doses of radiation. Similar effects were observed for vitamin C at much lower doses (10 microg/ml). Dose reduction factor (DRF) calculated for famotidine treatment was about 1.5, and above 2 for vitamin C treatment. These results suggest that both vitamin C and famotidine suppresses radiation-induced apoptosis when used with various doses of gamma-irradiation (4-12 Gy) probably via *OH radical scavenging and an intracellular antioxidation mechanism.     

Radioprotective potential of histamine on rat small intestine and uterus

The aim of this study was to improve knowledge about histamine radioprotective potential investigating its effect on reducing ionising radiation-induced injury and genotoxic damage on the rat small intestine and uterus. Forty 10-week-old male and 40 female Sprague-Dawley rats were divided into 4 groups. Histamine and histamine-5Gy groups received a daily subcutaneous histamine injection (0.1 mg/kg) starting 24 h before irradiation. Histamine-5Gy and untreated-5Gy groups were irradiated with a dose of whole-body Cesium-137 irradiation. Three days after irradiation animals were sacrificed and tissues were removed, fixed, and stained with haematoxylin and eosin, and histological characteristics were evaluated. Proliferation, apoptosis and oxidative DNA markers were studied by immunohistochemistry, while micronucleus assay was performed to evaluate chromosomal damage. Histamine treatment reduced radiation-induced mucosal atrophy, oedema and vascular damage produced by ionising radiation, increasing the number of crypts per circumference (239±12 vs 160±10; P<0.01). This effect was associated with a reduction of radiation-induced intestinal crypts apoptosis. Additionally, histamine decreased the frequency of micronuclei formation and also significantly attenuated 8-OHdG immunoreactivity, a marker of DNA oxidative damage. Furthermore, radiation induced flattening of the endometrial surface, depletion of deep glands and reduced mitosis, effects that were completely blocked by histamine treatment. The expression of a proliferation marker in uterine luminal and glandular cells was markedly stimulated in histamine treated and irradiated rats.The obtained evidences indicate that histamine is a potential candidate as a safe radio-protective agent that might increase the therapeutic index of radiotherapy for intra-abdominal and pelvic cancers. However, its efficacy needs to be carefully investigated in prospective clinical trials.Key words: histamine, ionising radiation, radio-protectors, small intestine, uterus.     

Generation of reactive oxygen species and radiation response in lymphocytes and tumor cells

Several types of lymphoid and myeloid tumor cells are known to be relatively resistant to radiation-induced apoptosis compared to normal lymphocytes. The intracellular generation of reactive oxygen species was measured in irradiated spleen cells from C57BL/6 and BALB/c mice and murine tumor cells (EL-4 and P388) by flow cytometry using dichlorodihydrofluoresceindiacetate and dihydrorhodamine 123 as fluorescent probes. The amount of reactive oxygen species generated per cell was low in the tumor cells compared to spleen cells exposed to 1 to 10 Gy of gamma radiation. This could be due to the higher total antioxidant levels in tumor cells compared to normal cells. Further, the changes in mitochondrial membrane potential and cytoplasmic Ca2+ content were appreciable in lymphocytes even at a dose of 1 Gy. In EL-4 cells, no such changes were observed at any of the doses used. About 65% of spleen cells underwent apoptosis 24 h after 1 Gy irradiation. However, under the same conditions, EL-4 and P388 cells failed to undergo apoptosis, but they accumulated in G2/M phase. Thus the intrinsic radioresistance of tumor cells may be due to a decreased generation of reactive oxygen species after irradiation and down-regulation of the subsequent events leading to apoptosis.