Effect of tritium on embryo and fetuses in rodents

在HTO致癌性研究中，3.6m戈伊/d剂量可引起小鼠寿命缩短，但在较低剂量下，未见肿瘤发生率、激素样反应、寿命缩短。用HTO和MNU联合治疗雌性SD大鼠，HTO治疗组的乳腺肿瘤没有增加，但HTO治疗组的肿瘤发展明显增加，为了确定HTO的相对生物学效应，进行了肠腺干细胞测定，60 mCi/mouse HTO没有杀死BCF 1小鼠，这与以前的报道相比是相当高的价值。氚气对新生儿的影响不大，但对后半胎的损伤是前半胎的2倍。在胚胎中，HTO引起的损伤似乎是独特的，但其特征正在研究中的胚胎。对脑发育的影响在这一组中才刚刚开始，主要观察分析睁眼、跑步和神经肽的变化。5 cGy戈伊的HTO引起与20 cGy戈伊的γ射线相同的体征。用5cGy的HTO预处理不同剂量γ射线照射的离体白血病细胞，其突变率均降低。在人白血病细胞系中，采用FISH技术鉴定γ射线引起的特异性标记。用这种方法，可在14天龄的骨髓细胞或40天龄的淋巴样细胞中鉴定出各自的新标记物。

In carcinogenesis study of HTO in mice, 3.6m Gy/day induced life-shortening, but no evidence was observed on the incidence of tumor development, hormetic sign, life shortening under the more lower HTO concentrations. By a combined treatment of HTO and MNU in female SD rats, there were no increase of mammary tumors in HTO treated group, but significant increase of tumor development was observed by HTO.To identify the relative biological effectiveness of HTO,stem cell assay of intestinal crypt was done and 60 m Ci/mouse HTO did not kill the BCF_1 mice, which is rather high value compare to the previous report. Tritium gas did not influence too much to the newborn babies, but it gave twice as much as of damage to the latter half of fetuses compared to the former half of fetuses. In embryonic fetuses, the damage caused by HTO seemed to be unique, but its characterisric are under investigation by Hamster's embryo. Influence on the brain development is just started in this group, and its main observation is to analyze eye-opening, running and changes of neuropeptides. By the dose of 5 c Gy of HTO,it induces synony-mous signs to the dose of 20 cGy of gamma ray. By pre-treatment of 5 cGy of HTO,leukemiccells in vitro exposed to various doses of gamma-ray showed decreased mutation brequency. In human leukemic cell lines, Fish technique was introduced to identify the definite markers caused by gamma-rays. By this method, 14 day of myeloid cells or 40 days of lymphoid cells were identified of respective new markers.Ingeno mice receiving lac Z genes are under development and establishment and introduction to our experiment should open new avenue.