大黄蒽醌衍生物与环核苷酸磷酸二酯酶、钙调素相互作用的研究

大黄蒽醌衍生物是中药大黄的主要成份。该类衍生物与钙调素(calmo-dulin,CaM)依赖的磷酸二酯酶(PDE)的相互作用表明:它们可作用子钙调素。其中,大黄酸结合CaM并抑制CaM依赖的磷酸二酯酶(CaM-PDE);而大黄素、大黄酚和芦荟大黄素既刺激CaM-PDE的活力,又刺激PDE的基础活力,其作用机制尚待阐明;当有Ca~(2+)或无Ca~(2+)条件下测定时,大黄酸对PDE基础活力均无影响。表明:象其它的CaM拮抗剂一样,大黄酸能抑制钙调素依赖的PDE的活力。     

用改进的寡核苷酸诱导突变法改造人胰岛素前体基因

我们用改进了的寡聚核苷酸诱导突变法,将两个单一限制性内切酶位点引入人胰岛素前体B链与C链连接处附近,及C链与A铁连接处附近。用含U模板法将B链第30个残基密码子ACC改成ACG,从而引入MluⅠ位点。用修改了的缺口双链DNA突变法,将A链第4个残基密码于GAG改成CTG,引入了一个PstⅠ位点。突变效率的为17％-36％。这个突变体在人胰岛素前体结构及蛋白质折叠的研究中,将有利于更换不同的C-肽。     

Ecological risk assessment of accidental release of flowback water: A conceptual framework

The aim of the study is to conduct an ecological risk assessment of accidental release of flowback water into freshwater body. Flowback water produced from the hydraulic fracturing process has a complex combination of high concentration of salts, organic compounds and metals. The toxicity of flowback water is assessed and an exposure assessment method for the inorganic constituents of the flowback water is developed. An equation for risk is derived to characterize the risk of the flowback water to the aquatic ecology. A case study is conducted for accidental release of hydraulic fracturing flowback water in Montney unconventional play trend in northern British Columbia. The flowback water quality data for 212 wells, including the concentrations of various salt ions, metal ions, and hydrogen sulfide, is collected for the assessment. The risk quotient is found to be 0.16 (<1), proving no significant risk to the aquatic ecosystem with 90% confidence. However, the overall results of the uncertainty and scenario analysis concludes that the risk to the ecology cannot be completely overlooked. Scenario analysis was done for monthly creek discharge and a relationship between risk quotient and the ratio of spill volume to the creek discharge was derived.     

Identification of miR-9 as a negative factor of insulin secretion from beta cells

MicroRNA is a novel class of small noncoding RNA that has been implicated in a variety of physiological and pathological processes, including glucose homeostasis and diabetes mellitus. So far, a few studies have reported that miRNAs may be an important regulator in glucose-stimulated insulin secretion (GSIS) pathway. However, the role of miRNAs in this process remains unclear. The levels of miRNAs in mouse islets and MIN6 cells were determined by quantitative RT-PCR. Concentration of insulin was determined by ELISA, and the expression of the target protein was determined with western blot assay. The overexpression and downregulation of miRNAs in MIN6 were conducted using cell transfection methods. And luciferase assay was used to measure the direct interaction between miRNAs and target messenger RNAs 3′UTR. miR-9 was screened out for it was downregulated under the effects of short-term high glucose, while long-term high glucose relatively increased miR-9 expression. The Stxbp1 expression was decreased with the overexpression of miR-9 in MIN6 cells and increased when miR-9 was downregulated. Moreover, it was verified by luciferase assay that miR-9 regulated Stxbp1 gene expression by directly targeting Stxbp1 messenger RNA 3′UTR. This study suggests that the pathway consisting of miR-9 and Stxbp1 plays a key role in β-cell function, thus contributing to the network of miRNA-insulin secretion and offering a new candidate for diabetes therapy.     

HPLC-based Measurement of Glycated Hemoglobin using Dried Blood Spots Collected under Adverse Field Conditions

Glycated hemoglobin (HbA1c) measured using high-performance liquid chromatography (HPLC) assays with venous blood and dried blood spots (DBS) are compared for 143 paired samples collected in Aceh, Indonesia. Relative to gold-standard venous-blood values, DBS-based values reported by the HPLC are systematically upward biased for HbA1c<8% and the fraction diabetic (HbA1c ≥ 6.5%) is overstated almost five-fold. Inspection of chromatograms from DBS assays indicates the % glycosylated calculated by the HPLC excludes part of the hemoglobin A which is misidentified as a hemoglobin variant. Taking this into account, unbiased DBS-based values are computed using data from the machine-generated chromatograms. When the DBS are collected in a clinic-like setting, under controlled humidity/temperature conditions, the recalculated values are almost identical to venous-based values. When DBS are collected under field conditions, the recalculated values are unbiased, but only about half the HbA1c values are measured reliably, calling into question the validity of the other half. The results suggest that collection conditions, particularly humidity, affect the quality of the DBS-based measures. Cross-validating DBS-based HbA1c values with venous samples collected under exactly the same environmental conditions is a prudent investment in population-based studies.     

Self-fitting shape memory polymer foam inducing bone regeneration: A rabbit femoral defect study

Although tissue engineering has been attracted greatly for healing of critical-sized bone defects, great efforts for improvement are still being made in scaffold design. In particular, bone regeneration would be enhanced if a scaffold precisely matches the contour of bone defects, especially if it could be implanted into the human body conveniently and safely. In this study, polyurethane/hydroxyapatite-based shape memory polymer (SMP) foam was fabricated as a scaffold substrate to facilitate bone regeneration. The minimally invasive delivery and the self-fitting behavior of the SMP foam were systematically evaluated to demonstrate its feasibility in the treatment of bone defects in vivo. Results showed that the SMP foam could be conveniently implanted into bone defects with a compact shape. Subsequently, it self-matched the boundary of bone defects upon shape-recovery activation in vivo. Micro-computed tomography determined that bone ingrowth initiated at the periphery of the SMP foam with a constant decrease towards the inside. Successful vascularization and bone remodeling were also demonstrated by histological analysis. Thus, our results indicate that the SMP foam demonstrated great potential for bone regeneration.     

A polysaccharide from Dictyophora indusiata inhibits the immunosuppressive function of cancer‐associated fibroblasts

Reversing the function of cancer‐associated fibroblasts (CAFs) may improve the efficacy of cancer therapy. Here, we isolated a novel polysaccharide from Dictyophora indusiata (ZSP4) and examined its effects on the function of prostate CAFs. The supernatant of prostate CAFs can stimulate the proliferation of immune cells and inhibit the growth of CD4+/CD8+ T cells. However, after ZSP4 stimulation, the functions of prostate CAFs were inhibited. The mechanism experiment shows that ZSP4 can stimulate prostate CAFs by down‐regulating the expression of α‐smooth muscle actin. Polysaccharides extracted from Dictyophora indusiata stimulate the proliferation of immune cells and reverse the immune‐suppressive functions of prostate CAFs, shedding new light on the development of novel anticancer strategies. The endocrine therapy used to treat prostate cancer aims to eliminate androgenic activity from prostatic tissue; these therapies are painful and of poor therapeutic effect. In this study, we found that polysaccharides extracted from Dictyophora indusiata may affect the micro‐environment of tumours and inhibit the growth of the tumours. Our results suggest that polysaccharides may modulate negative immune regulation and enhance antitumour immunity, which is important for clinical therapy.