An expression profile for diagnosis of lymph node metastases from primary head and neck squamous cell carcinomas

Metastasis is the process by which cancers spread to distinct sites in the body. It is the principal cause of death in individuals suffering from cancer. For some types of cancer, early detection of metastasis at lymph nodes close to the site of the primary tumor is pivotal for appropriate treatment. Because it can be difficult to detect lymph node metastases reliably, many individuals currently receive inappropriate treatment. We show here that DNA microarray gene-expression profiling can detect lymph node metastases for primary head and neck squamous cell carcinomas that arise in the oral cavity and oropharynx. The predictor, established with an 82-tumor training set, outperforms current clinical diagnosis when independently validated. The 102 predictor genes offer unique insights into the processes underlying metastasis. The results show that the metastatic state can be deciphered from the primary tumor gene-expression pattern and that treatment can be substantially improved.     

A high abundance of massive galaxies 3-6 billion years after the Big Bang

Hierarchical galaxy formation is the model whereby massive galaxies form from an assembly of smaller units. The most massive objects therefore form last. The model succeeds in describing the clustering of galaxies, but the evolutionary history of massive galaxies, as revealed by their visible stars and gas, is not accurately predicted. Near-infrared observations (which allow us to measure the stellar masses of high-redshift galaxies) and deep multi-colour images indicate that a large fraction of the stars in massive galaxies form in the first 5 Gyr (refs 4-7), but uncertainties remain owing to the lack of spectra to confirm the redshifts (which are estimated from the colours) and the role of obscuration by dust. Here we report the results of a spectroscopic redshift survey that probes the most massive and quiescent galaxies back to an era only 3 Gyr after the Big Bang. We find that at least two-thirds of massive galaxies have appeared since this era, but also that a significant fraction of them are already in place in the early Universe.     

Reconstructing galaxy histories from globular clusters

Nearly a century after the true nature of galaxies as distant 'island universes' was established, their origin and evolution remain great unsolved problems of modern astrophysics. One of the most promising ways to investigate galaxy formation is to study the ubiquitous globular star clusters that surround most galaxies. Globular clusters are compact groups of up to a few million stars. They generally formed early in the history of the Universe, but have survived the interactions and mergers that alter substantially their parent galaxies. Recent advances in our understanding of the globular cluster systems of the Milky Way and other galaxies point to a complex picture of galaxy genesis driven by cannibalism, collisions, bursts of star formation and other tumultuous events.     

Control of gene expression by a natural metabolite-responsive ribozyme

Most biological catalysts are made of protein; however, eight classes of natural ribozymes have been discovered that catalyse fundamental biochemical reactions. The central functions of ribozymes in modern organisms support the hypothesis that life passed through an 'RNA world' before the emergence of proteins and DNA. We have identified a new class of ribozymes that cleaves the messenger RNA of the glmS gene in Gram-positive bacteria. The ribozyme is activated by glucosamine-6-phosphate (GlcN6P), which is the metabolic product of the GlmS enzyme. Additional data indicate that the ribozyme serves as a metabolite-responsive genetic switch that represses the glmS gene in response to rising GlcN6P concentrations. These findings demonstrate that ribozyme switches may have functioned as metabolite sensors in primitive organisms, and further suggest that modern cells retain some of these ancient genetic control systems.     

Cancer chromosomes in crisis

The benign-to-malignant transition in human breast cancer is associated with a marked increase in chromosomal aberrations. A new study suggests that telomere dysfunction and its associated bridge-fusion-breakage cycles may drive this episodic instability, thereby providing aspiring cancer cells with the multiple genetic aberrations needed to achieve a fully malignant state.     

全球纳米技术研究文献计量分析

本研究采用文本挖掘技术，从在全球公开的纳米科学和技术研究文献数据库（SCI/SSCI 数据
库）中提取技术情报。在SCI/SSCI数据库中利用纳米科学和技术领域的300多个术语进行相关文献的检
索；利用摘要共现词汇的自相关图来揭示的技术核心领域；通过词汇间的互相关图来揭示因共现而发生
关系的词汇的技术核心领域；采用因子矩阵进一步量化研究机构之间、国家之间的关系强度，并对图中
揭示的合作出版网络给予确证。     

中美科技产出比较

该文以科技文献为分析基础,从数量与质量方面比较了中美之间科技发展的差距。数量比较选择了
SCI、INSPEC、Ei Compendex三大数据库,而质量比较则是应用了SCI中的引文分析。根据作者以前对中国
科技产出的评估,该文选择了30个技术研究领域,全面考察了中国在物质科学、环境、工程和生命科学重点
发展方向上论文数量情况。
SCI数据显示在几乎所有的技术领域内,虽然中国在论文数量方面增幅很大,但美国仍然处于领先地位
(2002－2007)。到2007年,INSPEC数据表明,在大多数技术领域内,中国的科技论文数量赶上或超过了美国;
但在生物医学和部分环境科学领域,美国仍然保持着较大的领先优势。Ei Compendex的数据分析结果表明,对
于大多数技术领域,到2007年中国的科技论文产量更大;而与日益增长的科研经费恰恰相反,美国发表论文的
数量似乎在2005年就已经到达了顶峰。如果不考虑生物医学领域,中国显然已经成为美国的强劲竞争对手。
为了对质量进行比较,该文对论文和引文数量进行了归一化处理,但仅限于纳米技术领域(1998－2003
年)。结果表明,虽然在过去的10年里美国在质量方面明显地领先中国(以及其他主要纳米技术研究国家),但
依然不能改表中国的论文质量持续提升的事实。中国目前已经达到可以与法国、意大利、日本和澳大利亚的
论文质量相提并论的地步。     

h指数研究在2007－2008年的新进展

该文对近期（2007－2008年）h指数及其衍生指数的发展进行了简单的回顾。