A Dual Tracer 18F-FCH/18F-FDG PET Imaging of an Orthotopic Brain Tumor Xenograft Model

Early diagnosis of low grade glioma has been a challenge to clinicians. Positron Emission Tomography (PET) using ¹⁸F-FDG as a radio-tracer has limited utility in this area because of the high background in normal brain tissue. Other radiotracers such as ¹⁸F-Fluorocholine (¹⁸F-FCH) could provide better contrast between tumor and normal brain tissue but with high incidence of false positives. In this study, the potential application of a dual tracer ¹⁸F-FCH/¹⁸F-FDG-PET is investigated in order to improve the sensitivity of PET imaging for low grade glioma diagnosis based on a mouse orthotopic xenograft model. BALB/c nude mice with and without orthotopic glioma xenografts from U87 MG-luc2 glioma cell line are used for the study. The animals are subjected to ¹⁸F-FCH and ¹⁸F-FDG PET imaging, and images acquired from two separate scans are superimposed for analysis. The ¹⁸F-FCH counts are subtracted from the merged images to identify the tumor. Micro-CT, bioluminescence imaging (BLI), histology and measurement of the tumor diameter are also conducted for comparison. Results show that there is a significant contrast in ¹⁸F-FCH uptake between tumor and normal brain tissue (2.65 ± 0.98), but with a high false positive rate of 28.6%. The difficulty of identifying the tumor by ¹⁸F-FDG only is also proved in this study. All the tumors can be detected based on the dual tracer technique of ¹⁸F-FCH/ ¹⁸F-FDG-PET imaging in this study, while the false-positive caused by ¹⁸F-FCH can be eliminated. Dual tracer ¹⁸F-FCH/¹⁸F-FDG PET imaging has the potential to improve the visualization of low grade glioma. ¹⁸F-FCH delineates tumor areas and the tumor can be identified by subtracting the ¹⁸F-FCH counts. The sensitivity was over 95%. Further studies are required to evaluate the possibility of applying this technique in clinical trials.     

不同寄主来源的马铃薯Y病毒群体遗传结构的比较分析

文章以马铃薯Y病毒(Potato virus Y, PVY) P3和pipo基因为分子标记,比较分析烟草和马铃薯两个寄主的PVY遗传多样性和群体分化,并评估突变、选择、基因流等遗传力所起的作用。通过P3和pipo基因计算获得的烟草和马铃薯群体分化指数F_ST分别为0.116和0.120,且统计检验差异显著,表明烟草和马铃薯寄主的PVY之间中度分化。变异分析结果显示,烟草分离物P3和pipo基因的核苷酸序列一致性分别为85.2%~100%和76.5%~100%,而马铃薯分离物的P3和pipo基因的核苷酸序列一致性分别为95.7%~100%和93.0%~100%,表明烟草PVY变异程度高于马铃薯。同时,P3基因内检测到大量的净化选择位点,表明该基因大部分位点的变异为有害突变,在进化过程中被剔除。此外,P3基因内还检测到两个显著正向选择位点,表明这两个位点的变异为有益突变,有利于病毒的生存竞争。在pipo基因中未检测到显著的选择位点,表明该基因上的变异基本不受自然选择影响。通过P3和pipo基因计算烟草和马铃薯群体间的基因流Nm值分别为1.91和1.83,表明这两个群体间存在较强的基因交流。以上结果表明,来源于烟草和马铃薯寄主的PVY遗传差异显著,突变、自然选择以及基因流都影响两者的遗传多样性及遗传分化程度。     

cDNA Microarray Analysis Revealing Candidate Biomineralization Genes of the Pearl Oyster, <Emphasis Type="Italic">Pinctada fucata martensii</Emphasis>

Biomineralization is a common biological phenomenon resulting in strong tissue, such as bone, tooth, and shell. Pinctada fucata martensii is an ideal animal for the study of biomineralization. Here, microarray technique was used to identify biomineralization gene in mantle edge (ME), mantle center (MC), and both ME and MC (ME-MC) for this pearl oyster. Results revealed that 804, 306, and 1127 contigs expressed at least three times higher in ME, MC, and ME-MC as those in other tissues. Blast against non-redundant database showed that 130 contigs (16.17 %), 53 contigs (17.32 %), and 248 contigs (22.01 %) hit reference genes (E?≤??10), among which 91 contigs, 48 contigs, and 168 contigs could be assigned to 32, 26, and 63 biomineralization genes in tissue of ME, MC, and ME-MC at a threshold of 3 times upregulated expression level. The ratios of biomineralization contigs to homologous contigs were similar at 3 times, 10 times, and 100 times of upregulated expression level in either ME, MC, or ME-MC. Moreover, the ratio of biomineralization contigs was highest in MC. Although mRNA distribution characters were similar to those in other studies for eight biomineralization genes of PFMG3, Pif, nacrein, MSI7, mantle gene 6, Pfty1, prismin, and the shematrin, most biomineralization genes presented different expression profiles from existing reports. These results provided massive fundamental information for further study of biomineralization gene function, and it may be helpful for revealing gene nets of biomineralization and the molecular mechanisms underlining formation of shell and pearl for the oyster.     

椎体成形术的生物力学研究现状和进展

椎体成形术是通过向椎体病损部位注入骨粘合剂,达到缓减疼痛、增强椎体稳定性的目的。由于椎体成形术的治疗原理、远期疗效、并发症均与其生物力学密切相关,其生物力学引起广泛的关注。本文通过椎体强化的生物力学研究方法及椎体强化后的生物力学特性,总结影响椎体强化效果的因素及影响程度,并对椎体强化生物力学研究中存在的问题及研究前景进行展望。     

Isolation and characterization of eleven microsatellite loci in small abalone, Haliotis diversicolor Reeve

Eleven novel microsatellite markers were isolated from small abalone, Haliotis diversicolor Reeve. These loci were tested on 22 individuals from two different geographic populations. We identified a total of 162 alleles from the 11 microsatellite loci. All of the loci were highly polymorphic. Polymorphism information content (PIC) is ranging from 0.7276 to 0.9163. Observed and expected heterozygosities ranged from 0.2727 to 1.0000 and from 0.7738 to 0.9429, respectively. Three loci deviated significantly from Hardy–Weinberg equilibrium. No pairs of loci displayed linkage disequilibrium. These polymorphic markers will be used to analyze population structure, genetic diversity and construct a genetic linkage map. Xin Zhan and Hai-Yan Hu contribute equally to this study.     

Polyclonal Antibodies in Microplates to Predict the Maximum Adsorption Activities of Enzyme/Mutants from Cell Lysates

With microplate-immobilized polyclonal antibodies against a starting enzyme or its active mutant bearing consistent accessible epitopes, the maximum activity of an adsorbed enzyme/mutant (Vs) was predicted for comparison to recognize weakly-positive mutants. Rabbit antisera against Escherichia coli alkaline phosphatase (ECAP) were fractionated with 33% ammonium sulfate to yield crude polyclonal antibodies for conventional immobilization in 96-well microplates. The response curve of the activities of ECAP/mutant adsorbed by the immobilized polyclonal antibodies to protein quantities from a cell lysate was fit to an approximation model to predict Vs. With 0.4 μg crude polyclonal antibody for immobilization, Vs was consistent for ECAP in cell lysates bearing fourfold differences in its apparent specific activities when its abundance was greater than 0.9%. The ratio of Vs of the mutant R168K to that of ECAP was 1.5?±?0.1 (n?=?2), consistent with that of their specific activities after affinity purification. Unfortunately, the prediction of Vs with polyclonal antibodies that saturated microplate wells was ineffective to Pseudomonas aeruginosa arylsulfatase bearing less than 2% specific activity of ECAP. Therefore, with microplate-immobilized polyclonal antibodies to adsorb enzyme/mutants from cell lysates, high-throughput prediction of Vs was practical to recognize weakly-positive mutants of starting enzymes bearing fairly-high activities.     

Genomic polymorphism of the pandemic A (H1N1) influenza viruses correlates with viral replication, virulence, and pathogenicity in vitro and in vivo

The novel pandemic A (H1N1) virus was first identified in Mexico in April 2009 and quickly spread worldwide. Like all influenzas, the H1N1 strain-specific properties of replication, virulence, and pathogenicity are a result of the particular genomic sequence and concerted expression of multiple genes. Thus, specific mutations may support increased virulence and may be useful as biomarkers of potential threat to human health. We performed comparative genomic analysis of ten strains of the 2009 pandemic A (H1N1) influenza viruses to determine whether genotypes associated with clinical phenotypes, which ranged from mild to severe illness and up to lethal. Virus replication capacity was tested for each strain in vitro using cultured epithelial cells, while virulence and pathogenicity were investigated in vivo using the BALB/c mouse model. The results indicated that A/Sichuan/1/2009 strain had significantly higher replication ability and virulence than the other strains, and five unique non-synonymous mutations were identified in important gene-encoding sequences. These mutations led to amino acid substitutions in HA (L32I), PA (A343T), PB1 (K353R and T566A), and PB2 (T471M), and may be critical molecular determinants for replication, virulence, and pathogenicity. Our results suggested that the replication capacity in vitro and virulence in vivo of the 2009 pandemic A (H1N1) viruses were not associated with the clinical phenotypes. This study offers new insights into the transmission and evolution of the 2009 pandemic A (H1N1) virus.     

地表蒸散的遥感估算模型及其在农业干旱监测中的应用

蒸散是地表水热交换的主要过程,其空间特征差异明显,而遥感技术的发展与应用使得区域蒸散估算成为现实.本文介绍了基于能量平衡法的单层与双层遥感蒸散模型,并对这2类遥感模型的优缺点分别进行了评述和比较.重点综述了近年来得到发展和应用的大气-陆地交换反演模型(ALEXI),阐述其主要结构、特色和过程.该模型通过耦合双层能量平衡模型(TSEB)和简化边界层模型,减少以往模型对台站气象数据的依赖,明显提高区域蒸散估算精度.研究表明,基于该模型的蒸散胁迫指数(ESI)具有很强的区域干旱监测能力.在今后研究中,多元遥感数据融合技术、陆面数据同化系统与遥感蒸散模型的结合将成为该领域的研究热点.