利用基于~1H NMR的代谢组学分析研究重离子辐射对大鼠额叶皮质区的影响

太空辐射尤其是重离子辐射可造成DNA的破坏、细胞死亡、以及一些癌症的发生, 是人类深空探索进程中急需克服的难题. 本文通过重离子加速器产生 ~(12)C~(6+)重离子束对大鼠头部进行一定剂量的辐射, 模拟空间重离子辐射对中枢神经系统(CNS)的生物学效应. 采用基于 ~1H NMR的代谢组学方法对辐射大鼠大脑额叶皮质区进行了测定分析, 结合数据的统计分析和检验, 发现了包括一些重要CNS神经递质在内的代谢物含量发生明显变化. 这些代谢物主要为: 牛磺酸、乳酸、谷氨酸、 4-氨基丁酸、以及磷酸胆碱等. 结合差异蛋白质组结果分析, 包括4-氨基丁酸、谷氨酸、乳酸、牛磺酸等在内的代谢物参与的主要生物途径, 如神经递质的合成途径, 以及神经递质受体介导的信号途径可能受重离子辐射的负面影响. 这些发现将为进一步阐明重离子辐射效应的分子机制提供有利信息, 从而为从生物学途径探寻有效重离子辐射防护措施提供依据.     

莽草酸途径中26种代谢物的NMR谱归属

莽草酸代谢途径广泛存在于植物、微生物与某些寄生虫中,是芳香氨基酸、植物激素与多种重要活性次生代谢物的主要合成通路.这些代谢物的系统核磁共振（NMR）研究尚不完备,且5-羟基吲哚乙酸与吲哚乳酸等代谢物的NMR数据归属尚不完整.本文对莽草酸代谢途径介导的26种代谢物（包括2种非芳香羧酸、2种植物激素、3种芳香类氨基酸、19种植物次生代谢物）结构进行了较为系统的NMR分析,对这些代谢物的¹H和¹³C NMR信号进行了归属,为植物化学及代谢组学研究提供了基础数据.     

1H MRS评价长期胰岛素治疗1型糖尿病大鼠海马代谢物的变化

本研究应用质子磁共振波谱（¹H MRS）技术对链脲佐菌素（STZ）诱导的1型糖尿病（T1DM）大鼠及长期胰岛素治疗的T1DM大鼠单侧海马的代谢物进行了分析. 结果发现,与对照组大鼠及胰岛素治疗组大鼠相比,T1DM模型组大鼠空腹血糖显著升高,体重显著降低（p < 0.05）.T1DM模型组肌醇（Ins）、牛磺酸（Tau）与谷氨酸（Glu）浓度较对照组显著升高（p = 0.000、p = 0.003、p = 0.014）.胰岛素治疗组Ins与Tau浓度较T1DM模型组显著降低（p = 0.000、p = 0.010）,与对照组无差别;而Glu、谷氨酸和谷氨酰胺（Glx）浓度较对照组显著升高（p = 0.007、p = 0.042）.本文结果表明T1DM大鼠海马区代谢物Ins浓度与Tau浓度对胰岛素治疗敏感.     

固体丁酸类代谢物13C化学位移的结构依赖性

丁酸类代谢物广泛存在于动物、植物和微生物中,且具有多种重要的生理功能,但它们的固体核磁共振参数、分子动力学性质及其结构依赖性并未得到清楚的认识. 该文使用高分辨交叉极化与魔角旋转核磁共振（¹³C CPMAS）实验技术,分析了一系列固体丁酸类代谢物的¹³C化学位移, 发现了这些代谢物的¹³C化学位移与其分子结构的一些相关性规律. 另外还发现,固体丁酸类代谢物与其在溶液中的¹³C化学位移有显著的差异. 这些代谢物中甲基参与的疏水作用以及羟基、氨基和羧基参与的氢键作用均对其化学位移大小有重要的影响. 上述结果为认识代谢物的结构和功能以及功能对结构的依赖性提供了重要信息.     

涡虫代谢物组成的核磁共振分析

作为扁形动物门的代表动物,涡虫因其特殊的演化地位和极强的再生能力,迅速成为实验动物学、细胞遗传学、发育生物学和再生生物学等研究中的理想模式生物. 众多与涡虫相关的研究都取得了突破性进展,而其在核磁共振和代谢组领域的相关科研报道却极为匮乏. 该研究使用甲醇水提取方法获得了涡虫身体提取物样品,同时利用高分辨的1 GHz NMR谱仪对该样品采集了¹H NMR谱图和5种2D NMR谱图（¹H-¹H COSY,¹H-¹H TOCSY,¹H-¹H J-RES,¹H-¹³C HSQC和¹H-¹³C HMBC）. 通过归属得到涡虫身体提取物里所含有的53种代谢物质,包括氨基酸、糖类、脂类、有机羧酸、酮体、胺类、胆碱类以及核苷酸等. 这些物质覆盖了多种代谢途径,为涡虫代谢组研究提供了基本的NMR相关信息.     

电离辐射对小鼠肾脏影响的代谢组学研究

电离辐射对生物体影响是目前生物医学领域研究的热点之一.本文利用基于核磁共振氢谱（¹H NMR）的代谢组学技术研究来自暴露于不同的电离辐射的C57BL/6J小鼠的肾脏的水溶性萃取物,并试图寻找电离辐射对小鼠肾脏影响的特异性生物标志物.分析结果表明,辐射组可与相应的对照组明显区分.在所发现的75个代谢物中,有6种代谢物的浓度发生显著性变化,分别为2-氨基丁酸、3-羟基丁酸、高丝氨酸、1,3-丙二胺、β-丙氨酸和抗坏血酸.这些代谢物可能成为高剂量电离辐射对生物体肾脏代谢影响的标志物.     

核子-核子碰撞截面对同位素标度参数α的介质效应

核子能量在40—60MeV能区范围,对在两对重离子中心碰撞系统⁴⁰Ca+⁴⁸Ca和⁶⁰Ca+⁴⁸Ca以及¹¹²Sn+¹¹²Sn和¹²⁴Sn+¹²⁴Sn 的反应中就同位素标度参数α对于核子-核子碰撞截面σ^med_NN(α_m)的介质 关键词： 同位素标度行为 介质效应 核子-核子碰撞截面 重离子碰撞     

核子-核子碰撞截面对同位素标度参数α的同位旋效应

对两对重离子中心碰撞系统⁴⁰C+⁴⁰Ca 和⁶⁰Ca+⁴⁰Ca以及¹¹²Sn+¹¹²Sn和¹²⁴Sn+¹²⁴Sn反应中就同位素标度参数α对于核子-核子碰撞截面的同位旋效应进行了研究.计算结果表明α对同位旋相关核子-核子碰撞截面σ^med_{NN关键词： 同位旋效应 核子-核子截面 机理 同位素标度}     

SIRT7基因低表达胶质瘤细胞株代谢特征的NMR分析

肿瘤是一种代谢疾病，癌基因表达对肿瘤细胞代谢的影响是目前肿瘤研究的热点之一.本文利用基于核磁共振氢谱（¹H NMR）的代谢组学方法对癌基因SIRT7低表达胶质瘤细胞株的代谢特征进行分析，寻找与SIRT7基因表达相关的特征性代谢物和代谢通路.分析结果表明，SIRT7基因低表达组与对照组细胞的代谢轮廓存在显著性差异，其细胞水溶性萃取物中有22种代谢物浓度发生明显变化.与对照组相比，SIRT7基因低表达胶质瘤细胞株中乳酸、甘氨酸、谷氨酸等12种代谢物浓度升高；缬氨酸、亮氨酸、赖氨酸等10种代谢物浓度降低.通路富集分析提示氨酰-tRNA生物合成、氨基酸代谢等代谢通路与SIRT7低表达密切相关.以上结果为进一步阐明癌基因SIRT7调控胶质瘤细胞代谢的作用机制提供了理论依据.     

电离辐射致植物诱变效应的损伤-修复模型

在电离辐射速率理论的基础上, 结合电离辐射诱导植物的微观与宏观生物效应, 建立了电离辐射致植物诱变效应的损伤-修复模型. 通过对理论模型平衡态的数值求解, 研究了辐照植物各状态相对浓度随电离辐射剂量的变化. 研究表明当考虑植物的修复作用时, 理论模型能够给出“马鞍型”的植物存活率-剂量关系. 为进一步验证模型, 对重离子⁷Li辐射玉米自交系的实验数据进行理论模型拟合, 确定重离子辐射玉米的诱变效应参数, 理论计算的结果与实验数据符合较好. 电离辐射诱导植物的损伤-修复模型的建立为电离辐射诱导植物生物效应的机理研究和辐射诱变植物育种提供了理论依据和参考.     

Mapping phosphorylation rate of fluoro-deoxy-glucose in rat brain by F chemical shift imaging

¹⁹F magnetic resonance spectroscopy (MRS) studies of 2-fluoro-2-deoxy-d-glucose (FDG) and 2-fluoro-2-deoxy-d-glucose-6-phosphate (FDG-6P) can be used for directly assessing total glucose metabolism in vivo. To date, ¹⁹F MRS measurements of FDG phosphorylation in the brain have either been achieved ex vivo from extracted tissue or in vivo by unusually long acquisition times. Electrophysiological and functional magnetic resonance imaging (fMRI) measurements indicate that FDG doses up to 500 mg/kg can be tolerated with minimal side effects on cerebral physiology and evoked fMRI-BOLD responses to forepaw stimulation. In halothane-anesthetized rats, we report localized in vivo detection and separation of FDG and FDG-6P MRS signals with ¹⁹F 2D chemical shift imaging (CSI) at 11.7 T. A metabolic model based on reversible transport between plasma and brain tissue, which included a non-saturable plasma to tissue component, was used to calculate spatial distribution of FDG and FDG-6P concentrations in rat brain. In addition, spatial distribution of rate constants and metabolic fluxes of FDG to FDG-6P conversion were estimated. Mapping the rate of FDG to FDG-6P conversion by ¹⁹F CSI provides an MR methodology that could impact other in vivo applications such as characterization of tumor pathophysiology.     

The First in Vivo Observation of C–N Coupling in Mammalian Brain

[5-¹³C,¹⁵N]Glutamine, with ¹J(¹³C–¹⁵N) of 16 Hz, was observed in vivo in the brain of spontaneously breathing rats by ¹³C MRS at 4.7 T. The brain [5-¹³C]glutamine peak consisted of the doublet from [5-¹³C,¹⁵N]glutamine and the center [5-¹³C,¹⁴N]glutamine peak, resulting in an apparent triplet with a separation of 8 Hz. The time course of formation of brain [5-¹³C,¹⁵N]glutamine was monitored in vivo with a time resolution of 20–35 min. This [5-¹³C,¹⁵N]glutamine was formed by glial uptake of released neurotransmitter [5-¹³C]glutamate and its reaction with ¹⁵NH₃ catalyzed by the glia-specific glutamine synthetase. The neurotransmitter glutamate C5 was selectively¹³C-enriched by intravenous [2,5-¹³C]glucose infusion to ¹³C-label whole-brain glutamate C5, followed by [¹²C]glucose infusion to chase ¹³C from the small and rapidly turning-over glial glutamate pool, leaving ¹³C mainly in the neurotransmitter [5-¹³C]glutamate pool, which is sequestered in vesicles until release. Hence, the observed [5-¹³C,¹⁵N]glutamine arises from a coupling between ¹³C of neuronal origin and ¹⁵N of glial origin. Measurement of the rate of brain [5-¹³C,¹⁵N]glutamine formation provides a novel noninvasive method of studying the kinetics of neurotransmitter uptake into glia in vivo, a process that is crucial for protecting the brain from glutamate excitotoxicity.     

Influence of 60Co gamma radiation on fluorine plasma treated enhancement-mode high- electron-mobility transistor

AlGaN/GaN depletion-mode high-electron-mobility transistor(D-HEMT) and fluorine(F) plasma treated enhancement-mode high-electron-mobility transistor(E-HEMT) are exposed to 60Co gamma radiation with a dose of 1.6 Mrad(Si).No degradation is observed in the performance of D-HEMT.However,the maximum transconductance of E-HEMT is increased after radiation.The 2DEG density and the mobility are calculated from the results of capacitance-voltage measurement.The electron mobility decreases after fluorine plasma treatment and recovers after radiation.Conductance measurements in a frequency range from 10 kHz to 1 MHz are used to characterize the trapping effects in the devices.A new type of trap is observed in the F plasma treated E-HEMT compared with the D-HEMT,but the density of the trap decreases by radiation.Fitting of G p /ω data yields the trap densities D T =(1-3) × 10 12 cm-2 · eV-1 and D T =(0.2 0.8) × 10 12 cm-2 ·eV-1 before and after radiation,respectively.The time constant is 0.5 ms-6 ms.With F plasma treatment,the trap is introduced by etch damage and degrades the electronic mobility.After 60Co gamma radiation,the etch damage decreases and the electron mobility is improved.The gamma radiation can recover the etch damage caused by F plasma treatment.     

Gamma-photon induced modifications in Polyvinylchloride (PVC) film

Gamma photon induced modifications in Polyvinylchloride (PVC) polymer have been studied in the dose range of 10¹-10⁶Gy at room temperature. Polyvinylchloride films have been irradiated with different doses of gamma radiation from a ⁶⁰Co source. To monitor the chemical and structural changes caused by gamma radiation IR and UV-Vis spectroscopy of pristine and irradiated PVC have been performed and using the spectral data some changes in the properties have been investigated. The spectral studies have indicated that at a dose of 10⁶Gy scissioning of the C-a bonds takes place. This scissioning of the chain initiates decomposition at a lower temperature. Thermal stability of the polymer reduces due to irradiation but the decomposition patterns remain the same. The optical band-gap is found to decrease due to irradiation at doses bigher than 10³Gy.     

Seasonal variations of radon and the radiation exposure levels in Nerja cave, Spain

²²²Rn concentrations in the air in Nerja cave (Spain) (3° 52′35′′W 36° 43′50′′N) were measured by continuous monitoring using Alpha-Guard, Genitron instrument equipment. The ²²²Rn measurements were carried out for a complete annual cycle in the different halls: Vestibule hall from July 2003 to June 2004, Ballet hall from July 2004 to June 2005 and Mirador hall from July 2005 to June 2006. Starting from the entrance of the cave we successively find the Vestibule hall, the Ballet hall and the Mirador hall. The range of ²²²Rn levels were of 8–627 Bq m⁻³ for the Vestibule hall, 28–575 Bq m⁻³ for the Ballet hall and 38–578 Bq m⁻³ for the Mirador. The aim of this study was to detect seasonal variation patterns of ²²²Rn concentrations. The seasonal variations of ²²²Rn concentrations are discussed in relation to various meteorological factors measured inside and outside the cave. The radiation exposure levels for workers and tourists with different equilibrium factors have been evaluated. The radiation exposure levels for workers and tourists only represent a low percentage of the exposure guides for the general population.     

Synchrotron radiation photoelectron spectroscopy and near-edge X-ray absorption fine structure study on oxidative etching of diamond-like carbon films by hyperthermal atomic oxygen

Surface structural changes of a hydrogenated diamond-like carbon (DLC) film exposed to a hyperthermal atomic oxygen beam were investigated by Rutherford backscattering spectroscopy (RBS), synchrotron radiation photoelectron spectroscopy (SR-PES), and near-edge X-ray absorption fine structure (NEXAFS). It was confirmed that the DLC surface was oxidized and etched by high-energy collisions of atomic oxygen. RBS and real-time mass-loss data showed a linear relationship between etching and atomic oxygen fluence. SR-PES data suggested that the oxide layer was restricted to the topmost surface of the DLC film. NEXAFS data were interpreted to mean that the sp² structure at the DLC surface was selectively etched by collisions with hyperthermal atomic oxygen, and an sp³-rich region remained at the topmost DLC surface. The formation of an sp³-rich layer at the DLC surface led to surface roughening and a reduced erosion yield relative to the pristine DLC surface.     

Biomedical Application of an Isotope Selective Nondispersive Infrared Spectrometer for 13CO2 and 12CO2 Concentration Measurements in Breath Samples

A newly developed isotope selective nondispersive infrared (NDIR) spectrometer for the measurement of ¹³CO₂ and ¹²CO₂ concentrations in breath samples was applied as a low cost and very simple to operate alternative to isotope ratio mass spectrometry (IRMS). We used this device for several biomedical applications ([¹³C]urea breath test, [¹³C]leucine metabolism, [¹³C]methacetin catabolism of rats) and found that the results agree very well with IRMS.     

Modification of the Fractionated γ-Radiation-Induced Alteration in the Na+/K+-ATPase Activity of Radiosensitive Tissues by Vitamin A

The effect of pre or post-administration of vitamin A in ameliorating the radiation-induced alteration in intestinal and spleen Na⁺/K⁺-ATPase activity of rats was determined. Rats subjected to multifractionated γ-radiation (20 × 0.5 Gy) over the whole-body showed a significant reduction in Na⁺/K⁺-ATPase activity being more obvious in spleen than in intestine. Administration of vitamin A at a daily i. p. dose of 15,000 IU/kg bd. wt. for 7 days prior to fractionated γ-irradiation and thereafter twice weekly throughout the exposure period (as pretreatment regimen) or following the end of irradiation for 7 days (as posttreament regimen) afforded a significant protection from radiation-induced inhibition of spleen and intestinal Na⁺/K⁺-ATPase activity. Even though, pretreatment regimen is more efficient against radiation injury to this enzyme than posttreatment, so that its activity was nearly normalized in the first regimen. The regeneration of normal enzyme activity in the tissues of the vitamin A-pretreated group suggests that the intestinal and spleen epithelia in presence of vitamin A are rendered relatively radioresistant.     

Cytotoxic and radiosensitizing effects of nano-C<Subscript>60 </Subscript>on tumor cells in vitro

There is growing evidence in recent years that the pristine fullerene may be endowed with strong pro-oxidant capacity to biological samples. In this investigation we tested the hypothesis that water-soluble fullerene-C₆₀ (nano-C₆₀) may interact with ionizing radiation enhancing its antiproliferative effects. The two tumor cell lines with different radiosensitivity B16 and SMMU-7721 were treated by a combination of pristine fullerene and ⁶⁰Co γ irradiation. We measured cell survival rates, apoptotic characteristics, reactive oxygen species (ROS) production and alteration of cell diameter with or without γ-irradiation. There was reduced survival with B16 and SMMU-7721 cells exposed to nano-C₆₀, with the inhibitory concentrations reducing the viability by 50% to 65 part per billion (ppb) and 150 ppb respectively. For cells exposed to nano-C₆₀ prior to γ-irradiation, damage to cell membranes and increased numbers of apoptotic cells were detected by morphologic Hoechst-staining analysis and Annexin V/propidium iodide double-staining. In cells exposed to nano-C₆₀, there were increased levels of ROS, as measured by fluorescence detection under laser confocal microscopy. Preincubation with non-toxic pristine C₆₀ before γ-ray caused enlargement of cells with increased diameter. The results show that nano-C₆₀ inhibits the growth of tumor cells at certain concentrations and increases the effects of ⁶⁰Co γ-irradiation, possibly through the elevated production of cellular ROS and the membrane disruption. Data in this study indicates a possible consideration of using C₆₀ as a candidate of sensitization modifier in tumor radiation biology.