Effects of sex hormones on induction of intestinal metaplasia by X-irradiation in rats.

The influence of sex hormones on induction of intestinal rnetaplasia was examined in 5 week old Crj: CD (SD) rats of both sexes. At the age of 4 weeks, the animals were gonadectornized and given testosterone or dimethyl estradiol (DES). One week after operation, they were irradiated with two 10 Gy doses of X-rays to the gastric region at a 3 day interval for a total of 20 Gy. At the termination of the experiment, 6 months after the X-irradiation, the incidence of intestinal metaplasia with alkaline phosphatase (ALP) positive foci in males was significantly higher than in females, in orchidectomized males or orchidectomized plus DES treated rats (P <0.01). On the other hand, the incidence of intestinal metaplasia with ALPpositive foci in normal females appeared lower than in ovariectomized females (P < 0.01), and was increased in rats by treatment with testosterone or decreased by DES. Numbers of foci of intestinal metaplasias with Paneth cells and total numbers appeared to increase in males treated with DES. The results suggested a promoting role for testosterone in the development of ALP positive lesions and indicated considerable heterogeneity between intestinal metaplasia subtypes.     

Identification of low-dose responsive metabolites in X-irradiated human B lymphoblastoid cells and fibroblasts

Ionizing radiation (IR) induces cellular stress responses, such as signal transduction, gene expression, protein modification, and metabolite change that affect cellular behavior. We analyzed X-irradiated human Epstein-Barr virus-transformed B lymphoblastoid cells and normal fibroblasts to search for metabolites that would be suitable IR-responsive markers by Liquid Chromotography–Mass spectrometry (LC–MS). Mass spectra, as analyzed with principal component analysis, showed that the proportion of peaks with IR-induced change was relatively small compared with the influence of culture time. Dozens of peaks that had either been upregulated or downregulated by IR were extracted as candidate IR markers. The IR-changed peaks were identified by comparing mock-treated groups to 100 mGy-irradiated groups that had recovered after 10 h, and the results indicated that the metabolites involved in nucleoside synthesis increased and that some acylcarnitine levels decreased in B lymphoblastoids. Some peaks changed by as much as 20 mGy, indicating the presence of an IR-sensitive signal transduction/metabolism control mechanism in these cells. On the other hand, we could not find common IR-changed peaks in fibroblasts of different origin. These data suggest that cell phenotype-specific pathways exist, even in low-dose responses, and could determine cell behavior.     

Synergistic Effect of Radiation on Colon Carcinogenesis Induced by Methylazoxymethanol Acetate in ACI/N Rats

The effect on colon and liver carcinogenicity in rats of a single X-irradiation exposure given either before or after methylazoxymethanol (MAM) acetate was studied in ACI/N rats of both sexes. A single dose of X-irradiation (3 Gy) was administered either 3 months before or after three weekly s.c. injections of MAM acetate (25 mg/kg body weight). At 365 days after the start, the incidence and multiplicity of MAM acetate-induced intestinal tumors were enhanced by X-irradiation either prior to or after the MAM acetate treatment. In addition, X-irradiation before MAM acetate increased the incidence of hepatocellular foci in either sex. In females, X-irradiation either before or after MAM acetate exposure decreased intestinal tumorigenesis. These findings suggest an apparent synergism of these agents in intestinal carcinogenesis of male rats.     

小鼠胸腺和牌细胞对淋巴因子反应的辐射剂量效应关系

作者研究了Ｃ５７ＢＬ／６小鼠经０．１～８．０ＧｙＸ射线全身照射后淋巴因子效应细胞反应性的变化．结果发现，照后２４小时胸腺细胞对ＩＬ－１反应的剂量效应曲线由两个斜率不同的成分组成，其Ｄ３７，分别为１．６５和４．０９Ｇｙ；照后１２和２４小时脾细胞对ＩＬ－２反应的Ｄ３７分别为５．５８和３．４６Ｇｙ；ＣＴＬＬ－２细胞在为０．５～１０Ｇｙ剂量范围内，对ＩＬ－２反应性呈剂量依赖性降低，Ｄ３７为８．７７Ｇｙ。提示ＩＬ－２效应细胞的辐射抗性高于ＩＬ－１效应细胞．     

3.0 Gy X线全身照射后对大鼠下丘脑—垂体—肾上腺皮质系统应激反应的影响

本文报道了3.0 GyX线全身照射后1、3日大鼠下丘脑—垂体—肾上腺皮质系统对应激刺激(一侧后肢骨折)的反应性变化。正常大鼠受应激刺激后10min,血浆β—EP、皮质酮、肾上腺和垂体的cAM P及下丘脑M—EnK水平都明显升高,而下丘脑β—EP含量则显著降低。照射后1日未应激组,血浆β—EP、皮质酮和垂体cAMP水平均显著高于正常对照,下丘脑β—EP也明显低于正常对照。照后1日应激组各参数虽明显高于正常对照,但与未应激组相比,除肾上腺cAMP和下丘脑B—EP水平显著升高外,其余各参数均差异不显著。照后3日未应激组,各参数都回降到接近正常水平。照后3日应激与未应激组相比,6项参数有4项显著增高,其余血浆皮质酮和下丘脑B—EP 2项虽有升高但差异不显著。结果表明,3.0GyX射线全身照射基本上未降低机体对应激的适应能力。     

Cryosections of pre-irradiated adult rat spinal cord tissue support axonal regeneration in vitro

Neonatal X-irradiation of central nervous system (CNS) tissue markedly reduces the glial population in the irradiated area. Previous in vivo studies have demonstrated regenerative success of adult dorsal root ganglion (DRG) neurons into the neonatally-irradiated spinal cord. The present study was undertaken to determine whether these results could be replicated in an in vitro environment. The lumbosacral spinal cord of anaesthetised Wistar rat pups, aged between 1 and 5 days, was subjected to a single dose (40 Gray) of X-irradiation. A sham-irradiated group acted as controls. Rats were allowed to reach adulthood before being killed. Their lumbosacral spinal cords were dissected out and processed for sectioning in a cryostat. Cryosections (10 μm-thick) of the spinal cord tissue were picked up on sterile glass coverslips and used as substrates for culturing dissociated adult DRG neurons. After an appropriate incubation period, cultures were fixed in 2% paraformaldehyde and immunolabelled to visualise both the spinal cord substrate using anti-glial fibrillary acidic protein (GFAP) and the growing DRG neurons using anti-growth associated protein (GAP-43). Successful growth of DRG neurites was observed on irradiated, but not on non-irradiated, sections of spinal cord. Thus, neonatal X-irradiation of spinal cord tissue appears to alter its environment such that it can later support, rather than inhibit, axonal regeneration. It is suggested that this alteration may be due, at least in part, to depletion in the number of and/or a change in the characteristics of the glial cells.     

Analysis of X-ray-induced aberrations in human chromosome 5 using high-resolution multicolour banding FISH (mBAND)

Peripheral lymphocytes were exposed to 4 Gy X-rays and aberrations were analysed in human chromosome 5 using high-resolution multicolour banding fluorescence in-situ hybridization (mBAND). This method is suited to detect simple and complex aberrations including peri- and paracentric inversions and exchanges between both chromosomes 5. Additionally, breakpoints can be assigned to specific regions in chromosome 5. Quantitative relationships of induced aberration types are discussed.     

钪—46内污染复合小剂量X射线全身外照射后 小白鼠骨髓有核细胞染色体畸变与剂量关系的研究

本文定量描述了钪—46内污染复合小剂量X射线全身外照射24h以后,小白鼠骨髓有核细胞染色体畸变与剂量的关系。结果表明,内外复合照射以后,染色体畸变率低于单纯内、外照射畸变率之和,但高于其中单一照射的畸变率,直线回归方程为y_6=7.9511+0.00099D_3,即呈正相关。染色体畸变率随时间变化规律为三项指数函数模式y(t)=2.9078exp~(0.27668t)+2.3786exp~(-0.017788t)+2.3786exp~(-0.1788t),1≤t≤30。经适宜性验证,各公式所得理论值的90％机率分布在实际测得值中。