MRT letter: Human bloodstains on antique aboriginal weapons: a guiding low-vacuum SEM study of erythrocytes in experimental samples on ethnographically documented biological raw materials

The aboriginal use of reed and bone as raw materials for knives and daggers, respectively, has been well-documented ethnographically in some geographical areas of Melanesia. Because of the significant role that these weapons played in inter- and intra-ethnic aggression, they can potentially have retained smears from the contact with human blood. To carry out a guiding low-vacuum scanning electron microscopy (SEM) study of specific interest to ethnography, the outsides of a fragment of stalk of giant cane (Arundo donax) and tibial diaphysis of domestic sheep (Ovis aries) were smeared with peripheral human blood. No biological specimen preparation was applied to the samples. After just over 1 month, bloodstain boundaries and their neighboring inner areas were examined via secondary electrons by a variable-pressure SEM (VP-SEM) working in low-vacuum mode. On both substrates, bloodstains exhibited micro-scales. No janocyte (erythrocyte negative replica) was observed in the examined areas. However, erythrocytes were seen crowded together as grain-shaped corpuscles in the smear on reed, and several hecatocytes (moon-like shaped erythrocytes) were evidenced in the smear on bone. The results of this study suggest that a VP-SEM working in low-vacuum mode can be used fruitfully to detect blood remains in medium-sized reed and bone antique aboriginal artifacts. This procedure can prospectively help to ethnographic museum curators and aboriginal-art surveyors as an easy guiding test in the valuation of antique traditional weapons prior to acquisition, when the real use of a piece has been claimed by the supplier.     

人工免疫系统中人工抗原提呈细胞的设计

反向选择模型是人工免疫系统中的经典模型,但存在训练代价高、覆盖率低的问题.危险理论模型是人工免疫系统中新引进的模型,在降低训练代价,提高覆盖率上具有优势.建立人工免疫危险理论模型必须解决的关键问题之一是:在保持人工免疫系统自适应特征的前提下,设计人工抗原提呈细胞.本文从抗原提呈细胞的生物学原理出发,设计了人工免疫系统中的人工抗原提呈细胞,给出单个人工抗原提呈细胞的结构、细胞上Toll样受体的结构,以及人工抗原提呈细胞群体的结构;设计了人工抗原提呈细胞群体的生命周期.初步的实验结果证明所设计的人工抗原提呈细胞具有自适应发现恶意软件的能力.     

Dynamics of polymer electrolyte fuel cells undergoing load changes

Numerical simulations are carried out for a single-channel polymer electrolyte fuel cell (PEFC) undergoing a step increase in current density. The objective is to elucidate profound interactions between the cell voltage response and water transport dynamics occurring in a low-humidity PEFC where the membrane hydration and hence resistance hinges upon the product water. Detailed results are presented to show that a step increase in the current density leads to anode dryout due to electroosmotic drag, while it takes several seconds for water back-diffusion and anode humidified gas to re-wet the anode side of the polymer membrane. The water redistribution process is controlled by water production, membrane hydration, electroosmotic drag, and water diffusion in the membrane. The anode dryout results in a substantial drop in cell voltage and hence temporary power loss. Under extreme situations such as dry anode feed, large step increase in the current density, and/or lower temperatures, the cell voltage may even reverse, resulting in not only power loss but also cell degradation. Finally, the dynamics of current distribution after a step change in gas humidification is numerically examined.     

碱性单细胞凝胶电泳预测肿瘤细胞内在放射敏感性研究

应用克隆形成法和碱性单细胞凝胶电泳技术检测辐射诱导的人红白血病细胞株K562、人结肠腺癌细胞株LS-T-117和鼠胶质瘤细胞株C6的初始DNA单链断裂数及单链断裂后的修复与细胞内在放射敏感性之间的关系。结果表明,3种细胞系的放射敏感性依次为K562>LS-T-117>C6;3种细胞系的DNA迁移距离都随着照射剂量的增加而增大,呈良好的剂量-效应关系。在相同剂量下,辐射诱导的DNA单链的初始断裂数目也依次为K562>LS-T-117>C6;3种细胞系经10Gy X射线照射并在PBS中培养不同时间后DNA迁移距离都有较大幅度的下降,但下降幅度依次为C6>LS-T-117>K562,在相同剂量下辐射诱导的DNA单链断裂后的修复能力也依次为C6>LS-T-117> K562。结果显示,辐射诱导的DNA单链断裂及修复与细胞内在放射敏感性有很好的相关性,可用于人体肿瘤细胞内在放射敏感性的预测。     

精脒含量对浓缩铀诱发PCI2细胞凋亡的影响

研究PC12细胞内精脒含量在浓缩铀诱导细胞凋亡中的作用。在PC12细胞中加入浓缩铀DMEM/F12工作液,计算PC12细胞的内照射吸收剂量,运用丹磺酰氯薄层分析技术测定细胞内游离精脒含量。结果表明,随着浓缩铀内照射时间的延长,细胞增殖活性迅速下降,DNA链断裂明显增多,放射性核素迅速渗入细胞核中,AO/EB染色可见凋亡细胞,同时细胞内游离精眯随内照射时程的延长而显著减少。表明浓缩铀可致PC12细胞的凋亡,细胞内游离精脒的含量可能与细胞活性有一定作用。     

The intracellular distribution of vinculin and alpha2 integrin in epithelial cells and chondrocytes

The purpose of this study was to demonstrate the presence of vinculin and alpha₂ integrin in chondrocytes in situ and epithelial cells. We also determined that the appropriate fixation and extraction protocols for immunohistochemistry and laser scanning confocal microscopy for an integral membrane protein and an actin-associated protein in cultured cells and whole tissue was different. Cultured epithelial cells, whole mount human cornea and avian cartilage were fixed and prepared using a number of standard procedures used for indirect fluorescence immunohistochemistry. The distribution of vinculin was cell-type and fixation-specific. Chondrocytes and cultured epithelial cells demonstrated vinculin in areas that appear to be associated with filamentous actin. Vinculin was associated with cell membranes in human cornea. The expression of alpha₂ integrin observed in chondrocytes fixed with methanol, paraformaldehyde, or formaldehyde is consistent with its role in cell-substrate interaction, but may also suggest a role in dividing and differentiating cells. The localization of alpha₂ integrin in human corneal epithelia supports its role as a cell-cell adhesion molecule. The cytoplasmic distribution of vinculin and alpha₂ integrin in tissues fixed without detergent extraction suggests that the fixation step may be sufficient for antibody penetration and antigen extraction. These studies are the first report of vinculin and alpha₂ integrin in embryonic chondrocytes. In addition we have shown that confocal laser scanning microscopy combined with proper fixation and extraction protocols may optimize the localization of antigens in cultured and whole mount cells.     

3Gy γ射线对不同肿瘤细胞细胞周期进程的影响

本实验旨在研究电离辐射对不同肿瘤细胞细胞周期进程的影响，为肿瘤的放射治疗提供科学依据。以3Gyγ射线照射指数生长期的肿瘤细胞，用流式细胞术测定细胞DNA含量并确定细胞周期各时相的细胞百分比。实验结果显示，γ射线照射后，SMMC-7721，hepG2和HO-8910细胞的G2／M期发生明显阻滞，且都在辐射后12h累积达到最大值，但S期只发生短暂的延迟，即辐射后6h明显累积，之后下降至接近对照水平或低于对照；Hela细胞的G2／M期和S期均发生显著阻滞。实验结果说明，电离辐射后，不同肿瘤细胞的G2／M期和S期检查点的激活和维持是有差异的。     

Bystander effect in human hepatoma HepG2 cells caused by medium transfers at different times after high-LET carbon ion irradiation

Although radiation-induced bystander effects have been well documented in a variety of biological systems, whether irradiated cells have the ability to generate bystander signaling persistently is still unclear and the clinical relevance of bystander effects in radiotherapy remains to be elucidated. This study examines tumor cellular bystander response to autologous medium from cell culture irradiated with high-linear energy transfer (LET) heavy ions at a therapeutically relevant dose in terms of clonogenic cell survival. In vitro experiments were performed using human hepatoma HepG2 cell line exposed to 100 keV/μm carbon ions at a dose of 2 Gy. Two different periods (2 and 12 h) after irradiation, irradiated cell conditioned medium (ICCM) and replenished fresh medium were harvested and then transferred to unirradiated bystander cells. Cellular bystander responses were measured with the different medium transfer protocols. Significant higher survival fractions of unirradiated cells receiving the media from the irradiated cultures at the different times post-irradiation than those of the control were observed. Even replenishing fresh medium for unirradiated cells which had been exposed to the ICCM for 12 h could not prevent the bystander cells from the increased survival fraction. These results suggest that the irradiated cells could release unidentified signal factor(s), which induced the increase in survival fraction for the unirradiated bystander cells, into the media sustainedly and the carbon ions triggered a cascade of signaling events in the irradiated cells rather than secreting the soluble signal factor(s) just at a short period after irradiation. Based on the observations in this study, the importance of bystander effect in clinical radiotherapy was discussed and incorporating the bystander effect into the current radiobiological models, which are applicable to heavy ion radiotherapy, is needed urgently.