The characteristics of a low background germanium gamma ray spectrometer at China JinPing underground laboratory

A low background germanium gamma ray spectrometer, GeTHU, has been installed at China JinPing Underground Laboratory (CJPL). The integral background count rate of the spectrometer was 0.629 cpm between 40 and 2700 keV, the origins of which were studied by Monte Carlo simulation. Detection limits and efficiencies were calculated for selected gamma peaks. Some samples of rare event experiments were measured and ¹³⁷Cs contamination was found in boric acid. GeTHU will be mainly used to measure environmental samples and screen materials in dark matter and double beta decay experiments.     

Use of gamma-spectrometry for simultaneous determination of 210Pb, 73As, 109Cd, 203Hg and 59Fe distribution and excretion in rats at low doses

γ-Spectrometry permits the identification and quantification of different γ-isotopes in the same aliquot. To estimate the sensitivity and discriminative power of a comparably small and inexpensive 8% germanium detector, we determined the detection limits for simultaneously applied ²¹⁰Pb, ⁷³As, ¹⁰⁹Cd, ²⁰³Hg and ⁵⁹Fe. The concentration of Fe and of each of the four potential environmental contaminants was determined in aliquots from all organs and tissues 10 days after simultaneous i.v. administration (2 μmol/kg body weight) to adult and growing iron-deficient and iron-adequate rats. Relating these values to the total size of each organ permitted to derive a whole body distribution pattern for all five isotopes in each individual animal. Cumulative renal and faecal excretion values were determined during the 10 day distribution period to calculate the half-lives for both excretory pathways for all five isotopes simultaneously. Distribution and excretion values corresponded well to literature data. Extrapolation of the results showed that the detector would be sensitive enough to discriminate and quantify the five metals at human dietary exposure levels. The results recommend to use γ-spectrometry to investigate kinetic aspects of interactions between toxic and essential trace metals, because the method reduces the number of required animals drastically.     

Germanium myopathy: clinical and experimental pathological studies

Summary Pathological examinations were carried out on the skeletal muscle of a patient with germanium intoxication. The prominent histochemical finding was vacuolar myopathy with lipid excess, increased acid phosphatase activity and decreased cytochrome c oxidase activity. Ultrastructural lesions revealed a mitochondrial abnormality, autophagic vacuoles and accumulation of high electron-dense materials in deformed mitochondria and at the periphery of lipid droplets. Furthermore, the toxic effect of germanium on skeletal muscle was confirmed by the experimentally induced germanium myopathy, which showed autophagic degeneration, decreased cytochrome c oxidase activity and a mitochondrial abnormality with high electron-dense materials.     

关于锗的必需性问题

<正> 在自然界存在的92种元素中,现已在人体中发现81种。根据其生物学作用,可将这些元素分为三类,即必需元素,可能必需元素和非必需元素。目前已知,必需元素共有26种,其中11种是常量元素,15种是微量元素。高等动物必需的微量元素是:Fe、I、Cu、Mn、Zn、Co、Mo、Se、Cr、Sn、V、F、Si、Ni 和 As。随着科学技术的发展,还可能发现一些微量元素对生命活动也是必需的。本文讨论锗的必需性问题。     

Comparison of organic and inorganic germanium compounds in cellular radiosensitivity and preparation of germanium nanoparticles as a radiosensitizer

Purpose: The aim of this work is to compare the radiosensitizing effect between organic and inorganic germanium compounds and to investigate whether nanometer-sized germanium particles can act as radiosensitizers.

Materials and methods: Bis (2-carboxyethylgermanium) sesquioxide (Ge-132), germanium oxide (GeO₂) and germanium nanoparticles were used in this study. Cell viability was determined by clonogenic survival assay. Cellular DNA damage was evaluated by alkaline comet assay, confocal microscopy and the cellular level of phospho-histone H2AX (γ-H2AX).

Results: Nanometer-sized germanium particles were fabricated. They have a similar radiosensitizing effect as that of GeO₂. Conversely, Ge-132 did not enhance the radiosensitivity of cells. Comet assay was employed to evaluate the level of DNA damage and confirmed that inorganic germanium compounds enhanced cellular radiosensitivity. Notably, the comet assay indicated that the nanoparticle itself caused a higher level of DNA damage. The possibility that germanium nanoparticles per se caused DNA damage was ruled out when the cellular level of γ-H2AX was examined.

Conclusions: We demonstrated that inorganic but not organic germanium compounds exerted radiosensitizing effect in cells. Nanometer-sized germanium particles were fabricated and were able to enhance the radiosensitivity of cells. Confounding effect may occur when comet assay is used to estimate the level of DNA damage in the presence of germanium nanoparticles.     

羧乙基锗倍半氧化物对正常和异丙基肾上腺素损伤培养乳鼠心肌细胞的影响

羧乙基锗倍半氧化物(Ge—132)能促进培养乳鼠心肌细胞DNA和RNA的合成,提高超氧化物歧化酶(SOD)的活性,维持细胞膜结构的稳定。异丙基肾上腺素可使心肌细胞乳酸脱氢酶(LDH)释放增加,细胞搏动停止,超微结构显示肌膜和线粒体严重受损。Ge—132可显著减少异两基肾上腺素引起心肌细胞释放LDH,维持细胞的搏动功能和超微结构的完整。     

二羧乙基锗倍半氧化物的抗大鼠实验性胃溃疡作用及其作用机理研究

二羧乙基锗倍半氧物(Dicarboxyethyl GermaniumSesquioxide,DEG)是人工合成的有机锗化合物。它能对抗Shay幽门结扎性溃疡的形成,使胃液中PGE_2含量增加,胃蛋白酶活性和游离酸度明显降低。DEG还能对抗消炎痛型,五肽胃泌素型和酒精型溃疡的形成,促进醋酸型溃疡的愈合,但对应激型和利血平型溃疡无对抗作用。DEG的主细胞分泌功能比对照组明显减弱。实验结果表明,DEG的抗溃疡作用可能与增加胃内PGE_2含量、抑制胃液分泌和促进蛋白质合成有关。     

中药中锗的涂钽石墨炉原子吸收测定

在石墨炉原子吸收法中采用石墨管涂钽和基体改进技术，对中药灵芝、人参中锗的含量进行了测定。１％吸收浓度达８ｐｇ，变异系数ＣＶ〈１０％，回收率在９３．６％￣１０６％之间。     

有机锗胶囊在正常人体内的药代动力学

１０名健康志愿者口服单剂量（２００ｍｇ）有机锗胶囊，测得血清中药物浓度在２．４４±０．３７ｈ达到峰值８５４．４±３０１．９ｎｇ／ｍｌ。有机锗在人体内的吸收和消除均较为迅速，其吸收速率常数Ｋａ为１．０９±０．３９ｈ－１，其消除相半衰期仅为１．８１±０．２２ｈ；血药曲线下面积为４２３１．４±１０３６．４ｎｇ·ｈ／ｍｌ。药时曲线符合一级吸收的单室模型。     

人参中微量元素锗的生物活性

人参足珍贵的中药材，在我国的药用历史悠久。人参中的微量元素对人体的生长发育、营养、代谢、内分泌、免疫等过程均有着极为重要的作用，本文主要论述了人参中微量元素锗的生物活性。