Poly (l-lysine) based semi-interpenetrating polymer network as pH-responsive hydrogel for controlled release of a model protein drug streptokinase

With the aim of developing a pH-sensitive controlled drug release system, a poly (L-lysine) (PLL) based cationic semi-interpenetrating polymer network (semi-IPN) has been synthesized. This cationic hydrogel was designed to swell at lower pH and de-swell at higher pH and therefore be applicable for achieving regulated drug release at a specific pH range. In addition to the pH sensitivity, this hydrogel was anticipated to interact with an ionic drug, providing another means to regulate the release rate of ionic drugs. This semi-IPN hydrogel was prepared using a free-radical polymerization method and by crosslinking of the polyethylene glycol (PEG)-methacrylate polymer through the PLL network. The two polymers were penetrated with each other via interpolymer complexation to yield the semi-IPN structures. The PLL hydrogel thus prepared showed dynamic swelling/de-swelling behavior in response to pH change, and such a behavior was influenced by both the concentrations of PLL and PEG-methacrylate. Drug release from this semi-IPN hydrogel was also investigated using a model protein drug, streptokinase. Streptokinase release was found to be dependent on its ionic interaction with the PLL backbones as well as on the swelling of the semi-IPN hydrogel. These results suggest that a PLL semi-IPN hydrogel could potentially be used as a drug delivery platform to modulate drug release by pH-sensitivity and ionic interaction.     

黑松,马尾松及其杂种的核型比较

分析了黑松、马尾松及其杂种的核型。其核型公式：黑松为Ｋ（２ｎ）＝２４－２０ｍ（６＿（ＳＡＴ）））＋４ｓｍ;杂种为Ｋ（２ｎ）＝２４＝２３ｍ＋１ｓｍ;马尾松为Ｋ（２ｎ）＝２４－２４ｍ（４＿（ＳＡＴ））。相对长度和臂比方差分析表明,两亲本和杂种差异显著。杂种在相对长度、全组染色体总长、最长与最短染色体比、臂比平均值以及染色体类型上均处于双亲之间。这些研究结果为进一步研究该天然杂种提供必要的细胞学资料。     

Neuritin Attenuates Neuronal Apoptosis Mediated by Endoplasmic Reticulum Stress In Vitro

Neuritin is an extracellular glycophosphatidylinositol-linked protein that promotes neuronal survival, differentiation, function, and repair, but the exact mechanism of this neuroprotective effect remains unclear. Meanwhile, endoplasmic reticulum stress (ERS) induced apoptosis is attracting increased attention. In this work, we hypothesized that neuritin inhibited ERS to protect cortical neurons. To check this hypothesis, we exposed primary cultured cortical neurons to oxygen and glucose deprivation (OGD) for 45 min followed by reperfusion (R) to activate ERS. We then performed resuscitation for 6, 12, 24, and 48 h. ERS-related factors such as glucose-regulated protein 78 (GRP78), caspase-12 and CHOP were detected by Western blotting and quantitative real-time polymerase chain reaction assay. Apoptosis was assessed by Annexin V binding and propidium iodide staining. Ultrastructural changes of endoplasmic reticulum were observed under a transmission electron microscope. Results showed that GRP78 expression significantly increased at 12, 24, and 48 h and peaked at 24 h. Caspase-12 and CHOP expression significantly increased in a time-dependent manner at 12, 24, and 48 h. GRP78, caspase-12 and CHOP expression as well as apoptosis rate of primary cultured neurons and the ultrastructural changes of endoplasmic reticulum in the OGD/R?+?neuritin group significantly improved compared with the OGD/R group. In conclusion, the neuroprotection function of neuritin may be involved in ERS pathways.     

The Regulation and Function of Histone Methylation

Histones are wrapped around by genomic DNA to form nucleosomes which are the basic units of chromatin. In eukaryotes histones undergo various covalent modifications such as methylation, phosphorylation, acetylation, ubiquitination and ribosylation. Histone modifications play a fundamental role in the epigenetic regulation of gene expression in multicellular eukaryotes. Histone methylation is one of the most important modifications occurring on Lysine (K) and Arginine (R) residues of histones, dynamically regulated by histone methyltransferases and demethylases. Identifications of such histone modification enzymes and to study how they work are the most fundamental questions needs to be answered. Uncovering the regulation and functions of the various histone methylation enzymes will help us to better understand the epigenetic code. This review summarizes the regulation of histone methyltransferases activity, the recruitment of methyltransferases and the distribution patterns and function of histone methylations.     

川芎及两种主要药效成分对废用性肌萎缩的影响

目的：探讨川芎及川芎中起活血作用的两种主要药效成分（阿魏酸钠和川芎嗪）对后肢去负荷大鼠比目鱼肌萎缩的影响与作用。方法：尾部悬吊法建立大鼠废用性肌萎缩模型,用免疫组化技术及血液流变学方法观察药物对比目鱼肌各项指标的影响。结果：与后肢去负荷大鼠相比①高剂量的阿魏酸钠和川芎嗪使比目鱼肌I型肌纤维横截面积分别增加了37.3%和39.4%（P〈0.05）;②三种药物均能明显抑制梭外肌纤维MHCII表达水平的升高（P〈0.01）;③使肌梭内核袋2纤维MHCII的表达由阳性转变为阴性;④并能明显降低低切变率下的全血粘度。结论：川芎及两种主要药效成分阿魏酸钠与川芎嗪均能不同程度地对抗废用性肌萎缩的发生,以高剂量川芎嗪与阿魏酸钠的药效最为明显。     

Molecular Characterization of Microbial Population Dynamics during Sildenafil Citrate Degradation

Little is known about pharmaceutical and personal care products pollutants (PPCPs), but there is a growing interest in how they might impact the environment and microbial communities. The widespread use of Viagra (sildenafil citrate) has attracted great attention because of the high usage rate, the unpredictable disposal and the unknown potential effects on wildlife and the environment. Until now information regarding the impact of Viagra on microbial community in water environment has not been reported. In this research, for the first time, the genetic profile of the microbial community, developing in a Viagra polluted water environment, was evaluated by means of the 16S and 18S rRNA genes, for bacteria and fungi, respectively, amplified by polymerase chain reaction (PCR) and separated using the denaturing gradient gel electrophoresis (DGGE) technique. The DGGE results revealed a complex microbial community structure with most of the population persisting throughout the experimental period. DNA sequences from bands observed in the different denaturing gradient gel electrophoresis profiles exhibited the highest degree of identity to uncultured bacteria and fungi found previously mainly in polluted environmental and treating bioreactors. Biotransformation ability of sildenafil citrate by the microbial pool was studied and the capability of these microorganisms to detoxify a polluted water ecosystem was assessed. The bacterial and fungal population was able to degrade sildenafil citrate entirely. Additionally, assays conducted on Daphnia magna, algal growth inhibition assay and cell viability determination on HepG2 human cells showed that biotransformation products obtained from the bacterial growth was not toxic. The higher removal efficiency for sildenafil citrate and the lack of toxicity by the biotransformation products obtained showed that the microbial community identified here represented a composite population that might have biotechnological relevance to retrieve sildenafil citrate contaminated sites.     

Vertical distribution of bacterial community structure in the sediments of two eutrophic lakes revealed by denaturing gradient gel electrophoresis (DGGE) and multivariate analysis techniques

Vertical distribution of bacterial community structure was investigated in the sediments of two eutrophic lakes of China, Lake Taihu and Lake Xuanwu. Profiles of bacterial communities were generated using a molecular fingerprinting technique, denaturing gradient gel electrophoresis (DGGE) followed by DNA sequence analysis, and the results were interpreted with multivariate statistical analysis. To assess changes in the genetic diversity of bacterial communities with changing depth, DGGE banding patterns were analysed by cluster analysis. Distinct clusters were recognized in different sampling stations of Lake Taihu. Canonical correspondence analysis (CCA) was carried out to infer the relationship between environmental variables and bacterial community structure. DGGE samples collected at the same sampling site clustered together in both lakes. Total phosphorus, organic matter and pH were considered to be the key factors driving the changes in bacterial community composition.     

Expression of a novel <Emphasis Type="Italic">OSPGYRP</Emphasis> (rice proline-, glycine- and tyrosine-rich protein) gene,which is involved in vesicle trafficking,enhanced cold tolerance in <Emphasis Type="Italic">E. coli</Emphasis>

A novel OSPGYRP gene encoding a rice proline-, glycine- and tyrosine-rich protein was isolated from cold-stress treated rice seedlings using suppression subtractive hybridization. Both amino acid sequence analysis and subcellular localization confirm that OsPGYRP is a novel protein involved in vesicle trafficking. The expression of the OSPGYRP gene was induced by cold, salt, and osmotic stress. In addition, expression of the OSPGYRP gene in E. coli increased the resistance to cold stress. These results show that OsPGYRP is a novel protein involved in vesicle trafficking and plays an important role in plant adaptation to stress. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.