Preparation and protein adsorption of porous dextran microspheres

In present work, porous dextran microspheres with good morphology were synthesized by reversed-phase suspension polymerization. Dextran was used as raw material, epichlorohydrin (ECH) as crosslinker, and dimethyl ether of polyethylene glycol (DMPE) as porogen. And porous dextran microspheres were prepared by freezing-drying method. The morphology of the porous dextran microspheres was characterized by the scanning electronic microscope (SEM). The dry and hydrated densities, average pore volume, porosity, hydroxyl content and equilibrium water content were measured. Micropore structure was found on the dextran microspheres. With the increase of porogen amount, the dry density decreased, the hydrated density, the average pore volume, porosity and equilibrium water content initially increased and then decreased, while the hydroxyl content increased. Bovine serum albumin (BSA) was used as an adsorbate model to examine the adsorption behavior of the porous microspheres. The saturated adsorption capacities of these microspheres ranged from 59.1 mg/g to 138.9 mg/g while the amount of porogen increased from 10% to 50%.     

Upregulation of the solute carrier family 7 genes is indicative of poor prognosis in papillary thyroid carcinoma

Background

The solute carrier (SLC) 7 family genes comprise 14 members and function as cationic amino acid/glycoprotein transporters in many cells, they are essential for the maintenance of amino acid nutrition and survival of tumor cells. This study was conducted to analyze the associations of SLC7 family gene expression with mortality in papillary thyroid carcinoma (PTC).

Methods

Clinical features, somatic mutations, and SLC7 family gene expression data were downloaded from The Cancer Genome Atlas database. Linear regression model analysis was performed to analyze the correlations between SLC7 family gene expression and clinicopathologic features. Kaplan-Meier survival and logistic regression analyses were performed to characterize the associations between gene expression and patients’ overall survival.

Results

Patient mortality was negatively associated with age and tumor size but positively increased cancer stage and absence of thyroiditis in PTC patients. Kaplan-Meier survival analysis indicated that patients with high SLC7A3, SLC7A5, and SLC7A11 expression levels exhibited poorer survival than those with low SLC7A3, SLC7A5, and SLC7A11 expression levels (P?<?0.05 for all cases). Logistic regression analysis showed that SLC7A3, SLC7A5, and SLC7A11 were associated with increased mortality (odds ratio [OR] 8.61, 95% confidence interval [CI] 2.3–55.91; OR 3.87, 95% CI 1.18–17.31; and OR 3.87, 95% CI 1.18–17.31, respectively.

Conclusion

Upregulation of SLC7A3, SLC7A5, and SLC7A11 expression was associated with poor prognosis in PTC patients, and SLC7 gene expression levels are potentially useful prognostic biomarkers.

     

城镇快速发展对河流温室气体溶存及扩散通量的影响——以重庆市黑水滩河流域场镇为例

场镇发展是西南山区城镇发展的重要模式,且大部分场镇沿河分布,快速城镇发展给河流水环境及生物地化过程带来了一系列影响,然而其对河流温室气体排放时空格局的影响及机制尚不清楚。选择流域场镇发展特征明显的黑水滩河为研究对象,于2014年9月、12月、2015年3月、6月,对流域内干、支流水体温室气体浓度及扩散通量进行分析,旨在阐明流域场镇式发展下河流温室气体排放时空特征及关键驱动因素。研究结果表明,黑水滩河干、支流水体年均二氧化碳分压(pCO_2)及甲烷(CH_4)、一氧化二氮(N_2O)浓度均处于过饱和状态,是大气温室气体的净排放源;流域内干、支流水体流经不同场镇区前后水体碳、氮、磷及叶绿素a含量均不同程度增加,从上游向下游呈现明显的污染累积;水体溶存pCO_2\\CH_4\\N_2O浓度及扩散通量在不同场镇前后也呈现显著增加的趋势,三种温室气体扩散通量平均增幅分别为25.88%、55.22%、99.64%;河流水体pCO_2与N_2O浓度及通量秋季高于其他季节,CH_4浓度及扩散通量春季最高,秋季次之,夏、冬季最低,温室气体浓度及排放的季节变化主要受温度和降雨格局共同影响。相关分析表明,pCO_2与水温和pH关系密切,而水体CH_4和N_2O浓度与水体碳、氮、磷等生源要素均呈显著的正相关关系,水体CH_4与N_2O浓度对生源要素输入极为敏感,流域场镇发展带来的河流污染负荷的增加可能对水体CH_4与N_2O排放产生明显的激发效应。本研究认为,山区河流流域内沿河串珠状场镇分布对河流水体生源要素及其他理化性质产生累积影响,进而改变了水体温室气体的产生与排放时空格局。     

Recent advances in TMEM16A: Structure,function, and disease

TMEM16A (also known as anoctamin 1, ANO1) is the molecular basis of the calcium-activated chloride channels, with ten transmembrane segments. Recently, atomic structures of the transmembrane domains of mouse TMEM16A (mTMEM16A) were determined by single-particle electron cryomicroscopy. This gives us a solid ground to discuss the electrophysiological properties and functions of TMEM16A. TMEM16A is reported to be dually regulated by Ca²⁺ and voltage. In addition, the dysfunction of TMEM16A has been found to be involved in many diseases including cystic fibrosis, various cancers, hypertension, and gastrointestinal motility disorders. TMEM16A is overexpressed in many cancers, including gastrointestinal stromal tumors, gastric cancer, head and neck squamous cell carcinoma (HNSCC), colon cancer, pancreatic ductal adenocarcinoma, and esophageal cancer. Furthermore, overexpression of TMEM16A is related to the occurrence, proliferation, and migration of tumor cells. To date, several studies have shown that many natural compounds and synthetic compounds have regulatory effects on TMEM16A. These small molecule compounds might be novel drugs for the treatment of diseases caused by TMEM16A dysfunction in the future. In addition, recent studies have shown that TMEM16A plays different roles in different diseases through different signal transduction pathways. This review discusses the topology, electrophysiological properties, modulators and functions of TMEM16A in mediates nociception, gastrointestinal dysfunction, hypertension, and cancer and focuses on multiple regulatory mechanisms regarding TMEM16A.     

Characterization of iron-sulfur cluster assembly protein isca from Acidithiobacillus ferrooxidans

IscA is a key member of the iron-sulfur cluster assembly machinery found in bacteria and eukaryotes, but the mechanism of its function in the biogenesis of iron-sulfur cluster remains elusive. In this paper, we demonstrate that Acidithiobacillus ferrooxidans IscA is a [4Fe-4S] cluster binding protein, and it can bind iron in the presence of DTT with an apparent iron association constant of 4·10²⁰ M^?1. The iron binding in IscA can be promoted by oxygen through oxidizing ferrous iron to ferric iron. Furthermore, we show that the iron bound form of IscA can be converted to iron-sulfur cluster bound form in the presence of IscS and L-cysteine in vitro. Substitution of the invariant cysteine residues Cys35, Cys99, or Cys101 in IscA abolishes the iron binding activity of the protein; the IscA mutants that fail to bind iron are unable to assemble the iron-sulfur clusters. Further studies indicate that the iron-loaded IscA could act as an iron donor for the assembly of iron-sulfur clusters in the scaffold protein IscU in vitro. Taken together, these findings suggest that A. ferrooxidans IscA is not only an iron-sulfur protein, but also an iron binding protein that can act as an iron donor for biogenesis of iron-sulfur clusters.