Free malonaldehyde determination in tissues by high-performance liquid chromatography

A high-performance liquid chromatographic method was developed for the quantification of free malonaldehyde (MA) in tissues. HPLC separation was performed using a TSK G1000 PW column (7.5-mm i.d. X 30 cm) with a mobile phase of 0.1 M Na3PO4 buffer, pH 8.0, at a flow rate of 0.6 ml/min. The eluant was monitored at 267 nm. Free MA in the tissue sample was separated and quantified in approximately 50 min. The lowest amount of MA that can be determined by this HPLC technique is approximately 1 ng per injection. This method was successfully applied to rat liver and beef, pork, and chicken muscle and was compared to the thiobarbituric acid (TBA) test. It was found to be more sensitive, accurate, and specific for the determination of free MA than the TBA method.     

生态系统的天气环境模拟模型

无论对于自然的还是人为管理的生态系统,天气都是最重要的一种环境条件。用系统分析方法对生态系统进行的研究使天气模拟越来越成为非常必要的了。本文首先介绍了一个美国天气模拟模型(WGEN)的数学原理。它用马尔柯夫链和Γ-分布组成降水量子模型,产生逐日降水量。用弱平稳过程和调和分析为工具建立另一个子模型,产生逐日最高温度、最低温度和太阳辐射量。通过常规的统计学方法或灰靶白化方法可以估计模型参数。于是,就可由WGEN生出Alabama州天气模型ALWGEN和北京天气模型BJWGEN。考虑到篇幅有限,本文没有具体介绍上述估计方法,也只是扼要介绍了用Monte Carlo Bootstrap方法进行模型校验和验证的问题。最后,简单地讨论了天气模拟模型的应用。如IPM研究中的风险分析,生态系统管理决策,农业生态区域规划等课题,对天气模型都有现实的或潜在的需要。     

Prognostic power of a lipid metabolism gene panel for diffuse gliomas

Lipid metabolism reprogramming plays important role in cell growth, proliferation, angiogenesis and invasion in cancers. However, the diverse lipid metabolism programmes and prognostic value during glioma progression remain unclear. Here, the lipid metabolism‐related genes were profiled using RNA sequencing data from The Cancer Genome Atlas (TCGA) and Chinese Glioma Genome Atlas (CGGA) database. Gene ontology (GO) and gene set enrichment analysis (GSEA) found that glioblastoma (GBM) mainly exhibited enrichment of glycosphingolipid metabolic progress, whereas lower grade gliomas (LGGs) showed enrichment of phosphatidylinositol metabolic progress. According to the differential genes of lipid metabolism between LGG and GBM, we developed a nine‐gene set using Cox proportional hazards model with elastic net penalty, and the CGGA cohort was used for validation data set. Survival analysis revealed that the obtained gene set could differentiate the outcome of low‐ and high‐risk patients in both cohorts. Meanwhile, multivariate Cox regression analysis indicated that this signature was a significantly independent prognostic factor in diffuse gliomas. Gene ontology and GSEA showed that high‐risk cases were associated with phenotypes of cell division and immune response. Collectively, our findings provided a new sight on lipid metabolism in diffuse gliomas.     

Class I and Class II Histone Deacetylases Are Potential Therapeutic Targets for Treating Pancreatic Cancer

Background

Pancreatic cancer is a highly malignant disease with an extremely poor prognosis. Histone deacetylase inhibitors (HDACIs) have shown promising antitumor activities against preclinical models of pancreatic cancer, either alone or in combination with chemotherapeutic agents. In this study, we sought to identify clinically relevant histone deacetylases (HDACs) to guide the selection of HDAC inhibitors (HDACIs) tailored to the treatment of pancreatic cancer.

Methodology

HDAC expression in seven pancreatic cancer cell lines and normal human pancreatic ductal epithelial cells was determined by Western blotting. Antitumor interactions between class I- and class II-selective HDACIs were determined by MTT assays and standard isobologram/CompuSyn software analyses. The effects of HDACIs on cell death, apoptosis and cell cycle progression, and histone H4, alpha-tubulin, p21, and γH2AX levels were determined by colony formation assays, flow cytometry analysis, and Western blotting, respectively.

Results

The majority of classes I and II HDACs were detected in the pancreatic cancer cell lines, albeit at variable levels. Treatments with MGCD0103 (a class I-selective HDACI) resulted in dose-dependent growth arrest, cell death/apoptosis, and cell cycle arrest in G2/M phase, accompanied by induction of p21 and DNA double-strand breaks (DSBs). In contrast, MC1568 (a class IIa-selective HDACI) or Tubastatin A (a HDAC6-selective inhibitor) showed minimal effects. When combined simultaneously, MC1568 significantly enhanced MGCD0103-induced growth arrest, cell death/apoptosis, and G2/M cell cycle arrest, while Tubastatin A only synergistically enhanced MGCD0103-induced growth arrest. Although MC1568 or Tubastatin A alone had no obvious effects on DNA DSBs and p21 expression, their combination with MGCD0103 resulted in cooperative induction of p21 in the cells.

Conclusion

Our results suggest that classes I and II HDACs are potential therapeutic targets for treating pancreatic cancer. Accordingly, treating pancreatic cancer with pan-HDACIs may be more beneficial than class- or isoform-selective inhibitors.     

IL-18在临床疾病中的作用

IL-18是新发现的一种细胞因子,它具有诱生IFN-γ的作用,在抗感染、抗肿瘤、免疫性疾病及免疫调节等诸多方面发挥着重要作用.本文就IL-18的来源、结构特点、生化性质、生物学作用及其在临床疾病中的作用做一简单综述.     

Population structure analysis and association mapping of bacterial blight resistance in <Emphasis Type="Italic">indica</Emphasis> rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.) accessions

Bacterial blight, caused by Xanthomonas oryzae pv. oryzae (Xoo), is a serious disease in rice production worldwide. To understand the genetic diversity of bacterial blight resistance a population consisting of 175 indica accessions from nine countries was collected and detected their association between SSR (Simple Sequence Repeat) markers and resistance to six bacterial races. The resistance phenotypes of various rice accessions were evaluated through artificial inoculation under controlled conditions in 2013 and 2014. Association analysis showed that 17 SSR markers were significantly associated with resistance to four bacterial races and the phenotypic variations explained (PVE) ranged from 7.43 to 15.05%. Among the 17 associated SSR markers, two SSR markers located in previously reported genes regions, and 15 SSR markers were newly identified in this study. These results validated a new approach to map resistance genes of rice to bacterial blight. These markers could be used for marker-assisted selection (MAS) in rice bacterial blight resistance breeding programs.     

β-连环素和上皮钙粘连素在肝细胞癌中的表达及其意义

目的探讨人肝癌组织中β-连环素(-βcatenin)和上皮钙黏连素(E-cadherin)的表达情况及其与肝癌转移的相关性。方法应用免疫组织化学、原位分子杂交和细胞图像分析技术对30例原发性肝细胞癌及其癌旁肝组织中-βcate-nin和E-cadherin的表达情况进行观察,并分析了两者的表达与门静脉有无癌栓之间的相关性。结果在癌旁肝组织中,β-catenin和E-cadherin蛋白主要在细胞膜表达,胞浆表达较少;而在肝癌组织中,两者的表达特征发生改变,胞膜表达明显减少或缺失,-βcatenin的胞浆表达增强,甚至可见核表达,而E-cadherin在癌细胞胞浆内也明显减少或缺失。-βcatenin在有门静脉癌栓组的表达强度(平均光密度)高于无门静脉癌栓组(P<0.05),而E-cadherin则相反。结论-βcatenin在肝癌组织中的异位表达、过表达及E-cadherin的表达下降在肝癌转移过程中可能起重要作用。     

Integrated analysis of DNA methylation and mRNA expression profiling reveals candidate genes associated with cisplatin resistance in non-small cell lung cancer

DNA methylation plays a critical role during the development of acquired chemoresistance. The aim of this study was to identify candidate DNA methylation drivers of cisplatin (DDP) resistance in non-small cell lung cancer (NSCLC). The A549/DDP cell line was established by continuous exposure of A549 cells to increasing concentrations of DDP. Gene expression and methylation profiling were determined by high-throughput microarrays. Relationship of methylation status and DDP response was validated in primary tumor cell culture and the Cancer Genome Atlas (TCGA) samples. Cell proliferation, apoptosis, cell cycle, and response to DDP were determined in vitro and in vivo. A total of 372 genes showed hypermethylation and downregulation in A549/DDP cells, and these genes were involved in most fundamental biological processes. Ten candidate genes (S100P, GDA, WISP2, LOXL1, TIMP4, ICAM1, CLMP, HSP8, GAS1, BMP2) were selected, and exhibited varying degrees of association with DDP resistance. Low dose combination of 5-aza-2′-deoxycytidine (5-Aza-dC) and trichostatin A (TSA) reversed drug resistance of A549/DDP cells in vitro and in vivo, along with demethylation and restoration of expression of candidate genes (GAS1, TIMP4, ICAM1 and WISP2). Forced expression of GAS1 in A549/DDP cells by gene transfection contributed to increased sensitivity to DDP, proliferation inhibition, cell cycle arrest, apoptosis enhancement, and in vivo growth retardation. Together, our study demonstrated that a panel of candidate genes downregulated by DNA methylation induced DDP resistance in NSCLC, and showed that epigenetic therapy resensitized cells to DDP.     

Mechanisms of regulating the Raf kinase family

The MAP Kinase pathway is a key signalling mechanism that regulates many cellular functions such as cell growth, transformation and apoptosis. One of the essential components of this pathway is the serine/threonine kinase, Raf. Raf (MAPKK kinase, MAPKKK) relays the extracellular signal from the receptor/Ras complex to a cascade of cytosolic kinases by phosphorylating and activating MAPK/ERK kinase (MEK; MAPK kinase, MAPKK) that phosphorylates and activates extracellular signal regulated kinase (ERK; mitogen-activated protein kinase, MAPK), which phosphorylates various cytoplasmic and nuclear proteins. Regulation of both Ras and Raf is crucial in the proper maintenance of cell growth as oncogenic mutations in these genes lead to high transforming activity. Ras is mutated in 30% of all human cancers and B-Raf is mutated in 60% of malignant melanomas. The mechanisms that regulate the small GTPase Ras as well as the downstream kinases MEK and extracellular signal regulated kinase (ERK) are well understood. However, the regulation of Raf is complex and involves the integration of other signalling pathways as well as intramolecular interactions, phosphorylation, dephosphorylation and protein-protein interactions. From studies using mammalian isoforms of Raf, as well as C. elegans lin45-Raf, common patterns and unique differences of regulation have emerged. This review will summarize recent findings on the regulation of Raf kinase.