Psychological stress induces chemoresistance in breast cancer by upregulating mdr1

Psychological distress reduces the efficacy of chemotherapy in breast cancer patients. The mechanism may be related to the altered neuronal or hormonal secretions during stress. Here, we reported that adrenaline, a hormone mediating the biological activities of stress, upregulates mdr1 gene expression in MCF-7 breast cancer cells via alpha(2)-adrenergic receptors in a dose-dependent manner. Mdr1 upregulation can be specifically inhibited by pretreatment with mdr1-siRNA. Consequently, adrenergic stimulation enhances the pump function of P-glycoprotein and confers resistance of MCF-7 cells to paclitaxel. In vivo, restraint stress increases mdr1 gene expression in the MCF-7 cancers that are inoculated subcutaneously into the SCID mice and provokes resistance to doxorubicin in the implanted tumors. The effect can be blocked by injection of yohimbine, an alpha(2)-adrenergic inhibitor, but not by metyrapone, a corticosterone synthesis blocker. Therefore, we conclude that breast cancers may develop resistance against chemotherapeutic drugs under psychological distress by over-expressing mdr1 via adrenergic stimulation.     

Genipin cross-linked alginate-chitosan microcapsules: membrane characterization and optimization of cross-linking reaction

The genipin cross-linked alginate-chitosan (GCAC) microcapsule, composed of an alginate core and a genipin cross-linked chitosan membrane, was recently proposed for live cell encapsulation and other delivery applications. This article for the first time describes the details of the microcapsule membrane characterization using a noninvasive and in situ method without any physical or chemical modifications on the samples. Results showed that the cross-linking reaction generated the fluorescent chitosan-genipin conjugates. The cross-linked chitosan membrane was clearly visualized by confocal laser scanning microscopy (CLSM). A straightforward assessment on the membrane thickness and relative intensity was successfully achieved. CLSM studies showed that the shell-like cross-linked chitosan membranes of approximately 37 microm in thickness were formed surrounding the microcapsule. The reaction variables, including cross-linking temperature and time significantly affected the fluorescence intensity of the membranes. Elevating the cross-linking temperature from 4 to 37 degrees C drastically intensified the membrane fluorescence, suggesting the attainment of a high degree of cross-linking on the chitosan membrane. Extended cross-linking time altered the cross-linked membranes in modulation. Although genipin concentration and cross-linking time had little effects on the membrane thickness, cross-linking at higher temperatures tended to form relatively thinner membranes.     

Prognostic significance of the systemic immune‐inflammation index in pancreatic carcinoma patients: a meta-analysis

Background: Systemic immune-inflammation index (SII) is a prognostic indicator for several malignancies, including pancreatic carcinoma; however, there is no consensus on its significance. In the current study, a systematic meta-analysis was used to explore the correlation between SII and prognosis in pancreatic carcinoma patients.Methods: PubMed, Embase and Cochrane Library databases were screened from inception to May 2020. Studies describing the prognostic role of SII in pancreatic carcinoma were then retrieved. The pooled hazard ratio (HR) and 95% confidence interval (CI) was calculated using random- or fixed-effects models to determine the correlation between SII and prognosis.Results: A total of four studies, comprising 1749 patients, met the inclusion criteria of the study and were therefore included in this meta-analysis. The meta-analysis showed that high SII indicated was correlated with worse overall survival (OS) in patients with pancreatic carcinoma (HR: 1.43, 95% CI: 1.24–1.65, P<0.001). These findings were validated through subgroup analyses, stratified by the American Joint Committee on Cancer (AJCC) stage. In addition, patients with high SII showed poorer cancer-specific survival (HR: 2.32, 95% CI: 1.55–3.48, P<0.001). However, analysis showed no significant correlations between SII and disease-free and relapse-free survival (RFS).Conclusion: These findings indicate that SII is a potential non-invasive and a promising tool for predicting clinical outcomes of pancreatic carcinoma patients. However, the current research did not explore whether neoadjuvant therapy has an effect on the prognostic value of SII. Further studies using adequate designs and larger sample sizes are required to validate these findings.     

富营养化与污染物间的相互作用及其生态效应

1　引　言进入 90年代 ,为了改善水环境条件 ,越来越多的国家认识到必须减少养分、稳定的有机物和金属元素的输入。富营养化和持续污染物 (Ｃｈｒｏｎｉｃｐｏｌｌｕｔａｎｔｓ)是当前全球水生态系统的两个主要问题[1 ,2 ]。尽管对富营养化和污染物已有很多研究 ,但很少调查二者之间的相互关系。有证据表明两者之间可能存在相互作用过程[5～ 7],但在自然的水生态系统中其作用的大小和关系尚不清楚。滇池是我国典型的遭受富营养化和重金属污染双重胁迫的高原湖泊 ,本研究以滇池富营养化和重金属污染为背景 ,通过室内模拟 ,初步探索富营养化和…     

Comprehensive metabolomic,proteomic and physiological analyses of grain yield reduction in rice under abrupt drought–flood alternation stress

Abrupt drought–flood alternation (T1) is a meteorological disaster that frequently occurs during summer in southern China and the Yangtze river basin, often causing a significant loss of rice production. In this study, the response mechanism of yield decline under abrupt drought–flood alternation stress at the panicle differentiation stage was analyzed by looking at the metabolome, proteome as well as yield and physiological and biochemical indexes. The results showed that drought and flood stress caused a decrease in the yield of rice at the panicle differentiation stage, and abrupt drought–flood alternation stress created a synergistic effect for the reduction of yield. The main reason for the decrease of yield per plant under abrupt drought–flood alternation was the decrease of seed setting rate. Compared with CK0 (no drought and no flood), the net photosynthetic rate and soluble sugar content of T1 decreased significantly and its hydrogen peroxidase, superoxide dismutase, peroxidase activity increased significantly. The identified differential metabolites and differentially expressed proteins indicated that photosynthesis metabolism, energy metabolism pathway and reactive oxygen species response have changed strongly under abrupt drought–flood alteration stress, which are factors that leads to the rice grain yield reduction.     

Reducing AsA Leads to Leaf Lesion and Defence Response in Knock-Down of the AsA Biosynthetic Enzyme GDP-D-Mannose Pyrophosphorylase Gene in Tomato Plant

As a vital antioxidant, L-ascorbic acid (AsA) affects diverse biological processes in higher plants. Lack of AsA in cell impairs plant development. In the present study, we manipulated a gene of GDP-mannose pyrophosphorylase which catalyzes the conversion of D-mannose-1-P to GDP-D-mannose in AsA biosynthetic pathway and found out the phenotype alteration of tomato. In the tomato genome, there are four members of GMP gene family and they constitutively expressed in various tissues in distinct expression patterns. As expected, over-expression of SlGMP3 increased total AsA contents and enhanced the tolerance to oxidative stress in tomato. On the contrary, knock-down of SlGMP3 significantly decreased AsA contents below the threshold level and altered the phenotype of tomato plants with lesions and further senescence. Further analysis indicated the causes for this symptom could result from failing to instantly deplete the reactive oxygen species (ROS) as decline of free radical scavenging activity. More ROS accumulated in the leaves and then triggered expressions of defence-related genes and mimic symptom occurred on the leaves similar to hypersensitive responses against pathogens. Consequently, the photosynthesis of leaves was dramatically fallen. These results suggested the vital roles of AsA as an antioxidant in leaf function and defence response of tomato.     

京津冀地区新型城镇化对土地生态效率影响的实证分析

近年来, 城市化进程的不断推进对城市土地利用及生态环境产生了极大影响。选取城镇化发展最为迅速与典型的京津冀地区作为研究区域, 采用超效率DEA模型及Malmquist效率指数, 从经济学角度分析2006-2015年土地生态效率的时空演变, 随后, 基于人口、富裕和技术(STRIPAT)模型, 构建新型城镇化发展水平的综合指标评价体系, 分析新型城镇化对土地生态效率的影响。研究结果表明: 京津冀地区城镇化发展水平与土地生态效率之间存在显著的正相关关系, 即城镇化水平的不断提升对土地生态效率的提高具有积极作用, 各城市土地生态效率在新型城镇化发展背景下存在明显的空间差异, 此外, 土地利用与管理技术水平的提高、环境政策的改变等均会对土地生态效率的提升产生积极影响。这项研究旨在为提高城市土地管理水平, 推动城市可持续发展提供决策支持。