Effect of krypton-containing gas mixture on Japanese quail embryo development]

Investigated were effects of gas mixture with up to 3.0 kgs/cm2 of krypton on the embryonic development of domesticated Japanese quail (Coturnix coturnix japonica dom.). Results demonstrated absence of a serious krypton effect on Japanese quail embryos. Development of embryos proceeded in due course; morphometrically the experimental embryos were essentially similar to controls. It should be noted that despite exposure to acute hypoxic hypoxia during the initial 12 hours of development in the krypton-containing gas mixture, viability of quail embryos was high enough which can be ascribed to the krypton protective action. Besides, an additional experiment showed that krypton partial pressure of 5-5.5 kgs/cm2 produces the narcotic effect on adult Japanese quails.     

Dynamics of calcium utilization for skeleton formation in Japanese quail embryos under the microgravity condition

Tibia and femur osteogenesis was studied in embryonic lower limbs developed in microgravity. The maximal difference in ash content of shell in the flight and control groups was registered on days 4, 10 and 14 amounting to 10.27; 9.56 and 12.95% respectively. Shell analysis for calcium showed the largest difference between the groups on day 4 (8.94 mg). However, this difference was not seen already on days 14 and 16. Hence, according to the results of the investigation, although shell calcium utilization and osteogenesis in flight embryos of the Japanese quail were retarded, by the time of hatching the morphological and chemical parameters of the lower limb bones were essentially same as of the ground controls.     

Histogenesis of the liver of Japanese quail embryos developed in the conditions of microgravity

The article reports the results of histogenetic studies of the liver extracted from Japanese quail embryos and hatchlings that had passed the embryonic and postnatal development in microgravity. Comparison of the liver from the flight and laboratory embryos showed identity of organogenesis and histogenesis processes in space and on Earth. However, it should be noted that early histogenetic development of the space embryo liver had been retarded which was concluded from an enlarged lumen in bile capillaries and loose arrangement of epithelium girders as compared with the control On day-10 post flight, the flight embryos exhibited liver induration through narrowing of sinusoids lumen. Haemopoietic zones became less numerous. By the end of embryonic development these histological differences of the flight and control liver disappeared essentially. Organogenesis and histogenesis of the liver obtained from the hatchlings that had spent 5 days in microgravity did not depart from the norm. However, inability of the birds to adapt to microgravity and ensuing starvation was the reason for dystrophic changes in the liver, venous congestion and increased histoleucocytic activity. All the liver changes faded away soon alter the hatchlings were settled in favorable life conditions     

Changes in relative biological effectiveness with depth of the Clatterbridge neutron therapy beam

We have measured the biological equivalence of the Clatterbridge neutron therapy beam [p(62)-Be] and the Hammersmith neutron therapy beam [d(16)-Be] using the mouse intestinal crypt assay. The ratio (NDR) of Clatterbridge neutron (n + gamma) dose relative to Hammersmith neutron dose (n + gamma) was found to be 1.2-1.13 over a dose/fraction range of 1.8-9 Gy at 2 cm deep in a Perspex phantom. It is shown that the effectiveness of the Clatterbridge beam was reduced with penetration into the phantom because of hardening of the beam to a maximum reduction of 11% at 12 cm deep in the phantom. The hardening of the beam with depth of penetration will need to be taken into account by clinicians in assessing the tumour dose and tissue tolerance. Relative biological effectiveness values for the Clatterbridge and Hammersmith neutron beams were also measured. All neutron doses for both Hammersmith and Clatterbridge beams are total doses (n + gamma) which comply with the European protocol for neutron dosimetry and include the gamma-ray component of dose.     

Lack of dose rate modification (0.0049 vs. 0.12 Gy/min) of fission-neutron-induced neoplastic transformation in C3H/10T1/2 cells.

Clonogenic survival and neoplastic transformation of asynchronous cultures of C3H/10T1/2 cells were used to assay the effect of dose protraction of reactor-produced fission neutrons. Cells were exposed to eight neutron doses ranging from 0.05 to 0.9 Gy delivered at 11.7 or at 0.49 cGy/min. For each dose level, high and low dose rate irradiations were performed on the same day. At each dose a similar effectiveness of fission neutron irradiation at high or low dose rates was measured for both cell survival and transformation. The combined high and low dose-rate data were analysed by two- or three-parameter models. Depending on the model used, values of the effectiveness per unit dose derived as parameters of linear terms of the respective dose-response curves were 0.9-1.2 Gy-1 for clonogenic survival and 5-8 x 10(-4) Gy-1 for neoplastic transformation. It is concluded that the modification of fission neutron dose-response curves by dose rate is negligible or absent in the range of doses and dose rates examined, in contrast to results with other sources of fission or fast neutrons.     

252Cf中子照射中国参考人模体24Na比活度的实验研究

目的 研究裂变中子谱照射中国参考人单位中子注量在血液中产生的24Na比活度AB/φ,并分析实验场所地板、墙壁和天花板等的散射中子对测量结果的影响.方法 利用强度约3×108中子/s的252Cf中子源对中国参考人模体进行照射.模体躯干尺寸按中国参考人制作,外壳由4 mm有机玻璃制成,内有人体组织当量液,主要元素的重量比为H∶N∶O∶C=10.6∶2.5∶63.2∶23.7,密度1.007g/cm3(20℃).中子源到模体长轴的照射距离d(m)分别为1.1、2.1、3.1和4.1.中子源和模体的剑突部位离地面1.6 m.结果 单位中子注量照射在模体内产生的24Na平均比活度与照射距离有关,根据实验结果推导出的AB/Φ的最大值(AB/ΦM)约为1.85×10-7Bq·cm2·g-1.结论 AB/ΦM相当于252Cf中子谱平行射线照射的情况,这一数据比文献报道的BOMAB模体的实验结果大3%.实验表明,在照射场所的地面、墙壁散射中子对24Na比活度有显著的贡献,但对入射中子的剂量贡献却相对较小.因此,在实际的中子照射事故中,利用血液24Na比活度估算受照者的中子剂量时,事故场所散射中子的贡献将导致过高估计中子剂量,需要进行修正.

Abstract：

Objective To investigate the specific activity of 24Na per unit neutron fluence,AB/Φ,in blood produced for Chinese reference man irratiaded by 252Cf neutron source,and to analyze the effects of scattering neutrons from ground,wall,and ceiling in irradiation site on it.MethodsA 252Cf neutron source of 3 × 108 n/s and the anthropomorphic phantom were used for experiments.The phantom was made from 4 mm thick of outer covering by perspex and the liquid tissue-equivalent substitute in it.The data of phantom dimensions fit into Chinese reference man.The weight ratios of H,N,O and C in substitute equal from source to long axis of phantom were 1.1,2.1,3.1 and 4.1 m,respectively.Both the neutron source and the position of xiphisternum of the phantom were 1.6 m above the floor.ResultsThe average specific activity of 24Na per unit neutron fluence was related to the irradiation-distances,d,and its The AB/ΦM corresponds to that of phantom irradiated by plane-parallel beams,and the value is about more 3% than that by BOMAB phantom reported in literature.It has shown that floor-( wall-)scattered neutrons in irradiation site have significant contribution to the specific activity of 24Na ,but they contributed relatively little to the induced neutron doses.Consequently,using the specific activity of 24 Na for assessing accidental neutron doses received by an individual,the contribution of scattered neutrons in accident site will lead dose to be overestimated,and need to be correct.     

Growth dynamics of housefly larvae on organic wastes in a biological human life support system

The time-course of the growth of Musca domestica larvae on organic wastes (human and Japanese quail excrements) was studied as a function of the egg density. An increase in the density of the substrate contamination reduced the weight of pupae and III instar larvae. The density effect in the case of quail excrements was seen earlier than in the case of human excrements. The larval weight on quail excrements was much lower than on human excrements, the density of substrate contamination being equal. On human excrements larvae grew more actively than on quail excrements--the magnitude of their relative increase was higher beginning with the 2nd day of development. The density effect and the time-course of the larval growth on the substrates used show that human excrements are a better nutrient medium for fly larvae.     

低剂量率裂变中子照射对大鼠外周血淋巴细胞亚群的影响

目的 探讨低剂量率中子长期照射对大鼠外周血细胞亚群的影响。方法 96只雄性大鼠分为对照组和照射组,照射组每天用低剂量率中子²⁵²Cf(吸收剂量率为0.35 mGy/h)照射20.5h,在照射的第14、28、42、56和70天(累积剂量分别为0.1、0.2、0.3、0.4和0.5 Gy)及停止照射后第35天各取8只大鼠,用血细胞计数仪检测大鼠外周血WBC、用流式细胞仪检测外周血CD4⁺CD3⁺、 CD8⁺CD3⁺、CD45RA⁺/CD161α⁺亚群的变化。结果 累积剂量为0.3、0.4及0.5 Gy时WBC明显低于对照组(P<0.05),停止照射后35 d,WBC显著低于对照组(P<0.01);累积剂量为0.1、0.3、0.4、0.5 Gy及停止照射后35 d,外周血CD4⁺CD3^-细胞比例显著高于对照组(P<0.01或<0.05);累积剂量为0.2和0.3 Gy时CD8⁺CD3^-细胞比例显著高于对照组(P<0.05或P<0.01)。而累积剂量为0.1 Gy时的CD4⁺CD3⁺细胞比例及0.1和0.2 Gy时的CD8⁺CD3⁺细胞比例明显高于同一天对照组(P<0.01或<0.05)。另外,低剂量率中子长期照射可使累积剂量为0.2~0.3 Gy的外周血NK细胞(CD161α⁺ CD45RA^-)显著升高,累积剂量为0.1~0.5 Gy及停止照射后35 d照射组的外周血B细胞(CD161α^- CD45RA⁺)比例明显下降。结论 低剂量率裂变中子长期照射可使外周血淋巴细胞TCR基因突变,使大鼠外周血WBC减少,淋巴细胞中B细胞减少,NK细胞细胞比例升高,这种变化在停止照射后一段时间仍可能难以恢复。     

Impact of hypoxic gas mixtures on embryogenesis of the Japanese quail

Avian embryogenesis is of great interest to investigators, as the germ developing outside mother's body, is capable to react briskly to any alteration in the outer world. The paper present experimental evidence of the impact of oxygen with physical and chemical properties modified by short-cycle no-heating adsorption (SNA) in a hypoxic gas mixture (10% O2) on the early embryogenesis of the Japanese quail. Low concentrations of oxygen are known to be a dramatically disturbing factor for embryo's morphology. It was demonstrated experimentally that four days before incubation bird are highly sensitive to oxygen deficiency which is responsible for developmental abnormalities. The use of SNA oxygen reduced the frequency of pathologies in the Japanese quail germs as compared with their controls incubated in gas environment containing medical oxygen generated by low-temperature rectification.     

Studies of the eating behavior of Japanese quail chicks in the early postnatal period]

Time of the eating reaction (response to video signals) and eating behavior shortly after hatching were studied in Japanese quail chicks whose embryonic development took place under normal or changed gravity. Chicks partially incubated in a changed gravity showed a much slower eating reaction when compared with the chicks the prenatal development of which occurred under the normal gravity. In the chicks incubated at 1 g and placed in individual cages immediately after dominating afferentation for the eating behavior was visual Observations in the study will be used as a basis for designing a technology for handling and maintenance of hatchlings of the Japanese quail as a potential heterotrophic component of space life support systems.     

Genetic effects induced by neutrons in Drosophila melanogaster I. Determination of absorbed dose.

A method to obtain the absorbed dose in Drosophila melanogaster irradiated in the thermal column facility of the Triga Mark III Reactor has been developed. The method is based on the measurements of neutron activation of gold foils produced by neutron capture to obtain the neutron fluxes. These fluxes, combined with the calculations of kinetic energy released per unit mass, enables one to obtain the absorbed doses in Drosophila melanogaster.     

Prenatal acoustic stimulation and feeding behavior of Japanese quail chicks (Coturnix coturnix japonica)

Effects of a prenatal rhythmic tone on behavior of Japanese quail chicks were studied on the next days after hatching. The acoustically stimulated chicks demonstrated a significantly more frequent following response, feeding reaction and comfortable behavior when hearing the tone as compared with their controls. Bandwidths stimulating this or another behavior were determined.     

bFGF基因在中子辐射肠道损伤和修复中的表达和意义

目的研究肠道经中子照后的病变特点、bFGF蛋白和mRNA的表达及意义。方法采用2．5～5．5Gy中子照射230只BALB／C小鼠，于照后6和12h、1～5d、7、10、14、21和28d分批活杀，采用免疫组化和原位杂交等技术研究bFGF基因在肠组织中的表达。结果照射后隐窝细胞见凋亡与坏死，并呈剂量相关性，2．5Gy组肠黏膜见明显损伤及恢复现象。bFGF蛋白和mRNA于正常肠上皮细胞阳性，其mRNA于血管内皮和间质细胞强阳性。2．5Gy照后3d内，bFGF蛋白进行性减少，照后5～10d，绒毛上皮细胞bFGF蛋白明显增加，5d达高峰，14d恢复至正常水平。4．0Gy以上照后4d内，bFGF进行性减少。bFGF mRNA与其蛋白出现相似的变化规律，其高峰见于照后3d，10d基本恢复至正常水平。结论一定剂量的中子辐射可使肠黏膜明显损伤，并呈剂量相关性；中子照射后肠内源性bFGF基因表达参与其损伤及修复的病理过程，可能对其损伤后的修复起促进作用。     

Extended use of alanine irradiated in experimental reactor for combined gamma- and neutron-dose assessment by ESR spectroscopy and thermal neutron fluence assessment by measurement of 14C by LSC

Gamma- and neutron doses in an experimental reactor were measured using alanine/electron spin resonance (ESR) spectrometry. The absorbed dose in alanine was decomposed into contributions caused by gamma and neutron radiation using neutron kerma factors. To overcome a low sensitivity of the alanine/ESR response to thermal neutrons, a novel method has been proposed for the assessment of a thermal neutron flux using the ¹⁴N(n,p) ¹⁴C reaction on nitrogen present in alanine and subsequent measurement of ¹⁴C by liquid scintillation counting (LSC).     

Effects of neutron irradiation on optical and chemical properties of CR-39: Potential application in neutron dosimetry

Effects of high-dose neutron irradiation on chemical and optical properties of CR-39 were studied using FTIR (Fourier Transform Infrared) and UV–vis (Ultraviolet–Visible) spectroscopy. The primary goal was to find a correlation between the neutron dose and the corresponding changes in the optical and chemical properties of CR-39 resulted from the neutron irradiation. The neutrons were produced by bombarding a thick Be target with 22-MeV protons. In the FTIR spectra, prominent absorbance peaks were observed at 1735 cm⁻¹ (CO stretching), 1230 cm⁻¹(C–O–C stretching), and 783 cm⁻¹(C–H bending), the intensities of which decreased with increasing neutron dose. The optical absorbance in the visible range increased linearly with the neutron dose. Empirical relations were established to estimate neutron doses from these optical properties. This technique is particularly useful in measuring high doses, where track analysis with an optical microscope is difficult because of track overlapping.     

民航飞机座舱中宇宙辐射中子剂量与飞行高度和地磁纬度关系探讨

目的为对民航机组人员飞行中所受宇宙辐射剂量进行全面评估，实测两条国际航线中子剂量并进行分析探讨。方法采用慢化ＢＦ３中子监测器，在北京—纽约和北京—斯德哥尔摩航线飞行的Ｂ－７４７飞机上进行了测量，起飞、着陆阶段每２ｍｉｎ测一次，巡航阶段第３０ｍｉｎ测试一次，高度和纬度利用飞机仪表读出，地磁纬度采用人造地球卫星环境手册的公式计算。以回归法处理中子剂量与飞行高度和地磁纬度的关系，得出曲线及公式。结果实测中子剂量占总剂量的２７％～４５％。北京—纽约航线中子剂量为２．９３６ｍＳｖ／１０００ｈ，北京—斯德哥尔摩航线为３．５０１ｍＳｖ／１０００ｈ，分别占总剂量的３７．５％和４２．３％，与电离成分的比例分别为１∶１．６７和１∶１．３７。宇宙辐射中子剂量随飞行高度增高呈指数型增大，随地磁纬度增高呈直线型增大。结论飞行高度是影响航线中子剂量的第一位因素。     

The relative biological effectiveness of fractionated doses of fast neutrons (42 MeVd----Be) for normal tissues in the pig. I. Effects on the epidermis and dermal vascular/connective tissues

The effects of fractionated doses of fast neutrons (42 MeVd----Be) on the early epithelial and later dermal response of pig skin have been assessed and compared with those after X irradiation. For the early epithelial reaction, i.e. moist desquamation, the relative biological effectiveness (RBE) of the neutron beam increased with the decreasing size of the X-ray dose/fraction. There was an experimentally observed upper RBE value of approximately 2.75 for X-ray doses/fraction of between 2 and 5 Gy. For the late reaction of ischaemic dermal necrosis the RBE was greater than 3.0 for X-ray doses/fraction of less than 3 Gy and, based on the assumptions made in the linearquadratic model of cell survival, an upper limiting RBE of 4.32 +/- 0.39 was calculated for infinitely small doses/fraction. These findings were compared with other radiobiological data and the conclusions drawn from the results of clinical trials. It was concluded that for the sparing of late effects in skin and subcutaneous tissues, relative to acute reactions, a relatively small number of fractions in a short overall treatment time may be optimal for fast neutron therapy.     

In vivo partial body activation analysis using filtered neutron beam

A facility for in vivo prompt γ-ray activation analysis using a filtered neutron beam from a mobile nuclear reactor is described. The low-power nuclear reactor with a thermal neutron absorber provides a maximum neutron flux of 11,000 neutron/cm² s in the liquid phantom positioned on the surface of the irradiation plane; uniformity of the neutron flux inside the phantom with unilateral and bilateral irradiations is investigated. The elemental concentration of toxic mercury in a body organ is determined from a rapid diagnostic irradiation with minimal radiation doses as well as high sensitivity.     

Dosimetric comparison at FiR 1 using microdosimetry, ionisation chambers and computer simulation.

Tissue equivalent proportional counter microdosimetry has been applied in the dosimetry of epithermal neutron beams as they can provide an independent and accurate method to determine gamma ray and neutron absorbed doses. Dosimetric comparison has been performed using a tissue equivalent proportional counter, dual ionisation chambers and DORT computer code at FiR 1 boron neutron capture therapy facility in Espoo, Finland. The three methods were applied to determine neutron and gamma ray absorbed doses at 25, 40, 60 and 120 mm depths along the beam centerline in a water-filled PMMA phantom. The determined absorbed doses were found to agree within the limits of the estimated uncertainties.     

快中子诱导人鼻咽癌细胞系凋亡的研究

目的　研究中子不同剂量照射人鼻咽癌（ＣＮＥ２） 细胞凋亡发生特点及与Ｘ射线所致凋亡的差异。探讨凋亡在中子治疗肿瘤中的作用及临床意义。方法　采用琼脂糖凝胶电泳及ＤＮＡ特异性荧光染色方法（Ｈｏｅｃｈｓｔ３３３４２） 检测照射后不同时间人鼻咽癌（ＣＮＥ２）细胞。结果　发现中子可诱导人鼻咽癌细胞发生凋亡,这种凋亡发生存在着一定的时间剂量相关性。在相同剂量照射下,同一时间点上,中子照射所致的凋亡反应强于Ｘ 射线所致的凋亡。结论　快中子照射离体细胞可引起较强的凋亡反应。中子杀伤肿瘤的机理可能也是主要通过凋亡途径来实现的。