Flow‐injection chemiluminescence method to detect a β2 adrenergic agonist

A new method for the detection of β₂ adrenergic agonists was developed based on the chemiluminescence (CL) reaction of β₂ adrenergic agonist with potassium ferricyanide–luminol CL. The effect of β₂ adrenergic agonists including isoprenaline hydrochloride, salbutamol sulfate, terbutaline sulfate and ractopamine on the CL intensity of potassium ferricyanide–luminol was discovered. Detection of the β₂ adrenergic agonist was carried out in a flow system. Using uniform design experimentation, the influence factors of CL were optimized. The optimal experimental conditions were 1 mmol/L of potassium ferricyanide, 10 µmol/L of luminol, 1.2 mmol/L of sodium hydroxide, a flow speed of 2.6 mL/min and a distance of 1.2 cm from ‘Y₂’ to the flow cell. The linear ranges and limit of detection were 10–100 and 5 ng/mL for isoprenaline hydrochloride, 20–100 and 5 ng/mL for salbutamol sulfate, 8–200 and 1 ng/mL for terbutaline sulfate, 20–100 and 4 ng/mL for ractopamine, respectively. The proposed method allowed 200 injections/h with excellent repeatability and precision. It was successfully applied to the determination of three β₂ adrenergic agonists in commercial pharmaceutical formulations with recoveries in the range of 96.8–98.5%. The possible CL reaction mechanism of potassium ferricyanide–luminol–β₂ adrenergic agonist was discussed from the UV/vis spectra. Copyright © 2014 John Wiley & Sons, Ltd.     

Source-sink landscape theory and its ecological significance

Exploring the relatiouships between landscape pattern and ecological processes is the key topic of landscape ecology,for which,a large number of indices as well as landscape pattern analysis model were developed.However,one problem faced by landscape ecologists is that it is hard to link the landscape indices with a specific ecological process.Linking landscape pattern and ecological processes has become a challenge for landscape ecologists."Source" and "sink" are common concepts used in air pollution research,by which the movement direction and pattern of different pollutants in air can be clearly identified.In fact,for any ecological process,the research can be considered as a balance between the source and the sink in space.Thus,the concepts of "source" and "sink" could be implemented to the research of landscape pattern and ecological processes.In this paper,a theory of sourcesink landscape was proposed,which include:(1) In the research of landscape pattern and ecological process,all landscape types can be divided into two groups,"source"landscape and "sink" landscape."Source" landscape contributes positively to the ecological process,while "sink" landscape is unhelpful to the ecological process.(2) Both landscapes are recognized with regard to the specific ecological process."Source" landscape in a target ecological process may change into a "sink"landscape as in another ecological process.Therefore,the ecological process should be determined before "source"or "sink" landscape were defined.(3) The key point to distinguish "source" landscape from "sink" landscape is to quantify the effect of landscape on ecological process.The positive effect is made by "source" landscape,and the negative effect by "sink" landscape.(4) For the same ecological process,the contribution of "source" landscapes may vary,and it is the same to the "sink"landscapes.It is required to determine the weight of each landscape type on ecological processes.(5) The sourcesink principle can be applied to non-point source pollution control,biologic diversity protection,urban heat island effect mitigation,etc.However,the landscape evaluation models need to be calibrated respectively,because different ecological processes correspond with different source-sink landscapes and evaluation models for the different study areas.This theory is helpful to further study landscape pattern and ecological process,and offers a basis for new landscape index design.     

Comparison of neurotoxicity of different aggregated forms of Aβ40, Aβ42 and Aβ43 in cell cultures

The abnormal deposition of amyloid‐β (Aβ) peptides in the brain is the main neuropathological hallmark of Alzheimer's disease (AD). Amyloid deposits are formed by a heterogeneous mixture of Aβ peptides, among which the most studied are Aβ40 and Aβ42. Aβ40 is abundantly produced in the human brain, but the level of Aβ42 is remarkably increased in the brain of AD patients. Aside from Aβ40 and Aβ42, recent data have raised the possibility that Aβ43 peptides may be instrumental in AD pathogenesis. Besides its length, whether the Aβ aggregated form accounts for the neurotoxicity is also particularly controversial. Aβ fibrils are generally considered as key pathogenic substances in AD pathogenesis. Nevertheless, recent data implicated soluble Aβ oligomers as the main cause of synaptic dysfunction and memory loss in AD. To further address this uncertainty, we analyzed the neurotoxicity of different Aβ species and Aβ forms at the cellular level. The results showed that Aβ42 could form oligomers significantly faster than Aβ40 and Aβ43 and Aβ42 oligomers showed the greatest level of neurotoxicity. Regardless of the length of Aβ peptides, Aβ oligomers induced significantly higher cytotoxicity compared with the other two Aβ forms. Surprisingly, the neurotoxicity of fibrils in PC12 cells was only marginally but not significantly stronger than monomers, contrary to previous reports. Altogether, our findings demonstrate the high pathogenicity of Aβ42 among the three Aβ species and support the idea that Aβ42 oligomers contribute to the pathological events leading to neurodegeneration in AD. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.     

Circ_0075829 facilitates the progression of pancreatic carcinoma by sponging miR‐1287‐5p and activating LAMTOR3 signalling

Pancreatic cancer (PC) is a leading cause of cancer‐related mortality globally. Though increasing evidence has demonstrated that circular RNAs (circRNAs) are linked to the development and progression of cancers, the biological functions of circRNAs in PC remain largely unexplored so far. Based on previous studies, Hsc_circ_0075829 (circ_0075829) was screened out and then further identified in PC clinical specimens and cell lines by real‐time PCR. After the stability tests, a series of in vitro and in vivo functional experiments were performed to investigate the role of circ_0075829 in PC development. Furthermore, fluorescent in situ hybridization (FISH), bioinformatics tools, dual‐luciferase assays and rescue experiments were conducted to clarify the regulatory mechanisms of circ_0075829 in SW1990 and BxPC‐3 cells. Compared with paracancerous tissues, the expression of circ_0075829 was increased in PC tissues, which was positively correlated with the clinical features of PC. Knockdown of circ_0075829 significantly suppressed the proliferative, migratory and invasive rates of SW1990 and BxPC‐3 cells both in vitro and in vivo. Bioinformatics analysis and dual‐luciferase reporter gene assay indicated that circ_0075829 could bind to miR‐1287‐5p. Mechanism research and rescue experiments demonstrated that circ_0075829 could regulate the LAMTOR3/p‐ERK signalling pathway via sponging miR‐1287‐5p in PC cell lines. Our data reveal that the circ_0075829 could facilitate the proliferation and metastasis of PC through circ_0075829/miR‐1287‐5p/LAMTOR3 axis.     

Sirtuin 5 regulates the proliferation,invasion and migration of prostate cancer cells through acetyl‐CoA acetyltransferase 1

Sirtuin 5 (SIRT5) is a NAD⁺‐dependent class III protein deacetylase, and its role in prostate cancer has not yet been reported. Therefore, to explore the diagnosis and treatment of prostate cancer, we investigated the effect of SIRT5 on prostate cancer. Sirtuin 5 was assessed by immunohistochemistry in 57 normal and cancerous prostate tissues. We found that the tissue expression levels of SIRT5 in patients with Gleason scores ≥7 were significantly different from those in patients with Gleason scores <7 (P < .05, R > 0). Further, mass spectrometry and pathway screening experiments showed that SIRT5 regulated the activity of the mitogen‐activated protein kinase (MAPK) pathway, which in turn modulated the expression of MMP9 and cyclin D1. Being a substrate of SIRT5, acetyl‐CoA acetyltransferase 1 (ACAT1) was regulated by SIRT5. SIRT5 also regulated MAPK pathway activity through ACAT1. These results revealed that SIRT5 promoted the activity of the MAPK pathway through ACAT1, increasing the ability of prostate cancer cells to proliferate, migrate and invade. Overall, these results indicate that SIRT5 expression is closely associated with prostate cancer progression. Understanding the underlying mechanism may provide new targets and methods for the diagnosis and treatment of the disease.     

Mechanomyography is more sensitive than EMG in detecting age-related sarcopenia

The aim of this work was to investigate the effects of age-related sarcopenia on the time and frequency domain properties of lower extremity muscles’ electromyographic and mechanomyographic activities. Healthy elderly (n=10, 64.5±4.5 yr) and young (n=10, 22.6±2.8 yr) were recruited as participants. Participants’ lean thigh volumes (LTV) and 1 RM (one repetition maximum) leg strength of quadriceps and maximum speed knee extension with different load levels (45%, 60% and 75% 1 RM) were recorded. The root mean square (RMS) and the mean frequency (MF) of the surface electromyography (EMG_RMS, EMG_MF) and mechanomyography (MMG_RMS, MMG_MF) signals were collected at vastus lateralis during concentric contraction with different intensity levels. Compared to the young, the elderly had significantly less LTV, absolute and relative maximal force, as well as absolute and relative maximal power (p<.05). EMG_MF of the elderly and the young increased monotonically from 45% to 75% 1 RM testing conditions. While the MMG_RMS of the young increased with testing intensities, the MMG_RMS of the elderly increased only from 45% to 60% but leveled off from 60% to 75% 1 RM testing conditions. The results indicate the declines of muscle mass, force and power production capacity with aging. The observations could be explained by neuromuscular performance and change of MU activation patterns may result from age-related sarcopenia. Aging affected muscle power more than muscle strength, which could be due to fast fiber reduction. This is supported by our observations that the MMG_RMS differences between the young and the elderly across all three intensity level where EMG_RMS was only different at the greatest intensity. We suggest that MMG could be used as an important measurement in studying muscle contraction in age-related sarcopenia.     

Preferential solvation of methylmercurated calf thymus deoxyribonucleic acid.

The changes in polymer-solvent interactions that occur when native calf thymus DNA is dialyzed against Na₂SO₄ solutions of a given ionic strength and buffer concentration but of varying concentrations in methylmercuric hydroxide have been investigated with the help of solution density measurements at 25 °C and pH 6.8–7.0. From measurements executed under equilibrium dialysis conditions at the three salt levels 5 mm, 0.05 m, and 0.5 m Na₂SO₄ (m refers to molality) and in the presence of 5 mm cacodylic acid buffer, the density increments $\text{(}\text{??}\text{?c}{}_2\text{)}{}_{\mathrm{\mu }}{}^0$ for native calf thymus DNA were determined as a function of CH₃HgOH concentration. $\text{(}\text{??}\text{?c}{}_2\text{)}{}_{\mathrm{\mu }}{}^0$ was found not to vary with organomercurial concentration, irrespective of the concentration of supporting electrolyte, until a certain CH₃HgOH concentration level has been reached, viz., , beyond which $\text{(}\text{??}\text{?c}{}_2\text{)}{}_{\mathrm{\mu }}{}^0$ increases strongly with increasing concentration of CH₃HgOH. As is shown by optical melting, $\text{(}\text{??}\text{?c}{}_2\text{)}{}_{\mathrm{\mu }}{}^0$ becomes a function of organomercurial concentration the moment DNA undergoes denaturation brought about by the complexing of CH₃HgOH with the various N-binding sites of the base residues in the DNA double helix.Polymer-solvent interactions, expressed in terms of preferential water interactions (“net hydration”) and preferential salt interactions (“salt solvation”), were derived from the $\text{(}\text{??}\text{?c}{}_2\text{)}{}_{\mathrm{\mu }}{}^0$ data in combination with data obtained on the preferential interaction of CH₃HgOH with denatured DNA and data on the partial specific volumes of all major solution components, gathered from density measurements on solutions with fixed concentrations of diffusible components. Evidence is presented which shows that denaturation in general decreases the net hydration while salt becomes preferentially associated with the polyelectrolyte. This process is further amplified by the interaction of CH₃HgOH with denatured DNA: Methylmercurated DNA alters the redistribution of diffusible components at dialysis equilibrium to such an extent that in a formal sense large amounts of water are rejected from the immediate vicinity of the polymer. The molecular implications of these findings are explored. The results are further discussed in the light of previous findings where the methylmercury-induced denaturation of DNA had been studied with the help of buoyant density measurements in a Cs₂SO₄ density gradient and by velocity-sedimentation in a variety of sulfate media.     

深海白色侧齿霉遗传转化体系建立及渗透压调控相关的EaSHO1基因功能

海洋中具有丰富的动植物及微生物资源,海洋真菌是其重要组成之一。我们前期的研究发现一株深海真菌白色侧齿霉Engyodontium album能产生具有抑菌活性的次级代谢产物engyodontiumin A,该化合物能抑制黑曲霉、金黄色葡萄球菌及创伤弧菌等病原菌的生长,是一种潜在的海洋源抗菌药物。目前,该菌遗传转化体系尚未建立,不利于开展次级代谢产物合成调控机制及其他功能基因研究。本研究成功制备了深海白色侧齿霉菌的原生质体,建立了借助聚乙二醇3350介导的原生质体转化体系,并将pCT74-sGFP载体成功导入白色侧齿霉的原生质体中,结果显示外源GFP能稳定表达。此外,为了明确白色侧齿霉菌是否能够开展基因敲除研究,通过氨基酸序列同源比对,我们选取酵母高渗甘油信号途径中的同源基因EaSHO1进行初步探究。利用同源重组的方法成功将目的基因EaSHO1的开放阅读框(ORF)替换成潮霉素磷酸转移酶基因(HPH),由此获得EaSHO1基因敲除突变体,并对突变体进行Southern杂交验证及初步的表型分析。结果表明,EaSHO1缺失不影响白色侧齿霉菌的营养生长及对高盐胁迫的响应,亚细胞定位结果显示EaS...     

Comprehensive binary interaction mapping of τ phosphotyrosine sites with SH2 domains in the human genome: Implications for the rational design of self-inhibitory phosphopeptides to target τ hyperphosphorylation signaling in Alzheimer’s Disease

Amino Acids - Human microtubule-associated protein Tau (τ) is abundant in the axons of neurons where it stabilizes microtubule bundles; abnormally hyperphosphorylated τ is a hallmark of...