试论云阳县人口激增与土地锐减的矛盾及对策

土地是人们赖以生存的物质基础,是其它任何东西不可代替的生产资料。离开了土地,人就不能生存下去,这是众所周知的真理。但是,目前人口的激增与土地锐减的矛盾越来越尖锐。据有关统计资料表明,1978—1988年全国耕地面积减少3.66×10~6ha,与此同时全国人口又猛增1.33亿,给农业粮食生产、     

Polysaccharides derived from Balanophora polyandra significantly suppressed the proliferation of ovarian cancer cells through P53‐mediated pathway

Ovarian cancer (OC) is ranked the first among the cancers threatening women's health. It attracts tremendous attention of cancer researchers because of its extremely high mortality rate. Recent studies have indicated that traditional herbal medicines (THMs) can play a pivotal role in cancer prevention and treatment. THMs are gaining popularity as a source of anti‐cancer agents. The plant of Balanophora polyandra, which has been used as a traditional herbal medicine, has been known for exhibiting potential haemostatic, analgesic, anti‐inflammatory and anti‐cancer properties. However, few studies on inhibitory effect of B. polyandra on OC have been performed. In the present study, we found that B. polyandra polysaccharides (BPP) induced cell cycle arrest at S phase, triggered apoptosis and inhibited migration and invasion of OC cells. Furthermore, we also found that there was a potential and close relationship between BPP and P53‐mediated pathway. Overall, these findings suggest that BPP can be a potential therapeutic agent for the treatment of OC.     

Synthesis of triazole nucleoside derivatives

5'-O-Mesyl-2',3'-O-isopropylidene ribonucleosides (4 and 12) were converted to their 5'-substituted nucleosides in good yields by reacted with NaN3 or KI. 2',3'-O-Isopropylidene ribonucleosides (3 and 11) were prepared in good yields from ribonucleosides 1 and 2 with a reaction mixture of acetone and triethyl orthoformate instead of using acetone diethyl acetal. Compound 1 or 2 was treated with 2-acetoxyisobutyryl halide (Cl or Br) to give 1-[2-O-acetyl-3-halo-3-deoxy-5-O-(2,5,5-trimethyl-1,3-dioxolan-4-on-2-yl)-beta-D-xylofuranosyl]-1,2,4-triazole-3-carboxamide (19, 22, and 23) in high yields. Instead of using 2-acetoxyisobutyryl bromide, the mixture of 2-acetoxyisobutyryl chloride and NaBr was employed in the synthesis of 22 and 23. Treatment of 19 with an activated Zn/Cu couple and deprotection gave 2',3'-anhydro nucleoside (21), and treatment of 22 and 23 with an activated Zn/Cu couple and a little of HOAc and deprotection gave corresponding 2',3'-unsaturated triazole nucleosides (24 and 25), respectively. The biological activity of the compounds (7-10, 15-18, and 24) was examined in human liver cancer cells (A-549), lung cancer cells (BEL-7402), and Flu-A cells.     

海拔对白肋烟质体色素含量及相关基因表达的影响

以‘鄂烟1号’为供试品种,于湖北恩施选取高、中、低3个海拔(海拔高度分别为1 560m、1 200m、800m)种植区,研究不同海拔白肋烟主要生育期(旺长期、成熟期)内烟叶质体色素含量及其合成代谢过程中相关基因表达的差异,探讨白肋烟质体色素代谢对海拔高度的生理响应机制。结果表明:烟叶叶绿素a、叶绿素b和叶绿素总量及旺长期类胡萝卜素总量均以中海拔地区最高,且显著或极显著高于其他海拔梯度;成熟期高海拔烟叶类胡萝卜素总量最高,且较旺长期明显增加。叶绿素及旺长期类胡萝卜素合成有关的基因均为中海拔表达最强,成熟期类胡萝卜素合成基因在高海拔表达最强。结果说明‘鄂烟1号’更适宜种植在中海拔地区。     

Synthesis and evaluation of 2-[2-(phenylthiomethyl)-1H-benzo[d] imidazol-1-yl)acetohydrazide derivatives as antitumor agents

A novel class of acetylhydrazone derivatives (5a-x) containing 2-(phenylthiomethyl)-1H-benzo-[d]-imidazole moieties are synthesizer, and their antitumor activities against A549, HCT116, HepG2, PC-9, and A375 were determined by the MTT assay. Among them are N-(2,4-dihydroxybenzylidene)-2-(2-(phenylthiomethyl)-1H-benzo[d]-imidazol-1-yl)acetohydrazide (5a) and N-(5-bromo-2-hydroxy-benzylidene)-2-(2-(phenylthiomethyl)-1H-benzo[d]-imidazol-1-yl)acetohydrazide (5d) which displayed excellent cancer inhibitory activity against the tested cancer cells (IC(50) 4-17 μM), compared with 5-FU and SU11248. The others have moderate to weak inhibitory activity against the tested cancer cell lines.     

Development of a compact capillary electrophoresis–chemiluminescence system with ultra‐fast peroxyoxalate reaction to monitor the hydrolysis of rhodamine 6G

A simple and effective capillary electrophoresis–chemiluminescence (CE–CL) detection system was developed based on an ultra‐fast bis(2,4,6‐trichlorophenyl)oxalate (TCPO) chemiluminescence (CL) reaction (0.6 s duration) that avoided overlapping peaks and peak tailing. Through a series of static injection experiments, this unusually rapid CL reaction was ascribed to the catalytic effect of imidazole in the tetrahydrofuran solvent, which has been rarely utilized in such investigations. A possible mechanism is given to explain the results. Under the optimized conditions, rhodamine 6 G (R6G) and its hydrolysis product (R6G‐COOH) could be efficiently separated through electrophoresis in 7 min, with sensitive CL detection in the proposed CE–CL system. In this way, the alkaline hydrolysis of R6G was monitored, followed by estimation of relative rate constants and activation energy. This finding and application should be helpful in further study for the TCPO CL reaction, and revealed an attractive opportunity for simplifying the CE–CL system, such as in a microchip device. Copyright © 2011 John Wiley & Sons, Ltd.     

药用前胡研究进展

介绍了中药前胡近10年来的植物资源、化学成分和药理作用的研究成果,详细阐述了其主要药用部位药理作用研究的最新进展.     

Differential expression of microRNAs associated with neurodegenerative diseases and diabetic nephropathy in protein l-isoaspartyl methyltransferase-deficient mice

Protein l -isoaspartyl methyltransferase (PIMT/PCMT1), an enzyme repairing isoaspartate residues in peptides and proteins that result from the spontaneous decomposition of normal l -aspartyl and l -asparaginyl residues during aging, has been revealed to be involved in neurodegenerative diseases (NDDs) and diabetes. However, the molecular mechanisms for a putative association of PIMT dysfunction with these diseases have not been clarified. Our study aimed to identify differentially expressed microRNAs (miRNAs) in the brain and kidneys of PIMT-deficient mice and uncover the epigenetic mechanism of PIMT-involved NDDs and diabetic nephropathy (DN). Differentially expressed miRNAs by sequencing underwent target prediction and enrichment analysis in the brain and kidney of PIMT knockout (KO) mice and age-matched wild-type (WT) littermates. Sequence analysis revealed 40 differentially expressed miRNAs in the PIMT KO mouse brain including 25 upregulated miRNAs and 15 downregulated miRNAs. In the PIMT KO mouse kidney, there were 80 differentially expressed miRNAs including 40 upregulated miRNAs and 40 downregulated miRNAs. Enrichment analysis and a systematic literature review of differentially expressed miRNAs indicated the involvement of PIMT deficiency in the pathogenesis in NDDs and DN. Some overlapped differentially expressed miRNAs between the brain and kidney were quantitatively assessed in the brain, kidney, and serum-derived exosomes, respectively. Despite being preliminary, these results may aid in investigating the pathological hallmarks and identify the potential therapeutic targets and biomarkers for PIMT dysfunction-related NDDs and DN.     

Improved Sp1 and Betaine Homocysteine-S-Methyltransferase Expression and Homocysteine Clearance Are Involved in the Effects of Zinc on Oxidative Stress in High-Fat-Diet-Pretreated Mice

Zinc plays a role in alleviating oxidative stress. However, the related mechanisms remain to be further elucidated. The present study was conducted to investigate whether the recovery of oxidative stress in high-fat-diet (HFD)-pretreated mice was affected by zinc. Male mice received either an HFD or a low-fat-diet (LFD) for 8 weeks. Then, the mice fed with HFD and LFD were both assigned to either a control diet (30 mg zinc, ZD) or a no-added zinc diet (NZD) for an additional 4 weeks. The results showed that after feeding with NZD for 4 weeks, the HFD-pretreated mice had the highest plasma glucose and insulin concentrations, while had the lowest CuZn-SOD and glutathione concentrations. Moreover, after feeding with NZD for 4 weeks, the HFD-pretreated mice had the highest hepatic ROS and homocysteine concentrations, while had the lowest glutathione and methionine concentrations. Furthermore, the HFD-pretreated mice fed with NZD for 4 weeks had the lowest gene and protein expression of betaine homocysteine-S-methyltransferase (BHMT), cystathionine β-synthase, and Sp1. The results suggested that zinc was critical for oxidative stress alleviation and homocysteine clearance in HFD-pretreated mice. It was further elucidated that improved Sp1 and BHMT expression are involved in the effects of zinc on oxidative stress.     

Facile, efficient approach to accomplish tunable chemistries and variable biodistributions for shell cross-linked nanoparticles

The in vivo behavior of shell cross-linked knedel-like (SCK) nanoparticles is shown to be tunable via a straightforward and versatile process that advances SCKs as attractive nanoscale carriers in the field of nanomedicine. Tuning of the pharmacokinetics was accomplished by grafting varied numbers of methoxy-terminated poly(ethylene glycol) (mPEG) chains to the amphiphilic block copolymer precursors, together with chelators for the radioactive tracer and therapeutic agent (64)Cu, followed by self-assembly into block copolymer micelles and chemical cross-linking throughout the shell regions. (64)Cu-radiolabeling was then performed to evaluate the SCKs in vivo by means of biodistribution experiments and positron emission tomography (PET). It was found that the blood retention of PEGylated SCKs could be tuned, depending on the mPEG grafting density and the nanoparticle surface properties. A semiquantitative model of the density of mPEG surface coverage as a function of in vivo behavior was applied to enhance the understanding of this system.