Transforming crystal structures of cobalt molybdate to generate electron-rich sites for electrochemical detection of Pb(II).

BACKGROUND: Most of the investigations on distinct crystal structures of catalysts are individually focused on the difference of surface functional groups or adsorption properties, but rarely explore the changes of active sites to affect the electrocatalytic performance. Catalysts with diverse crystal structures had been applied to modified electrodes in different electrocatalytic reactions. However, there is currently a lack of an essential understanding for the role of real active sites in catalysts with crystalline structures in electroanalysis, which is crucial for designing highly sensitive sensing interfaces. RESULTS: Herein, cobalt molybdate with divergent crystal structures (α-CoMoO4 and ß-CoMoO4) were synthesized by adjusting the calcination temperature, indicating that α-CoMoO4 (800 °C) (60.00 µA µM-1) had the highest catalytic ability than ß-CoMoO4 (700 °C) (38.68 µA µM-1) and α-CoMoO4 (900 °C) (29.55 µA µM-1) for the catalysis of Pb(II). It was proved that the proportion of Co(II) and Mo(IV) as electron-rich sites in α-CoMoO4 (800 °C) were higher than ß-CoMoO4 (700 °C) and α-CoMoO4 (900 °C), possessing more electrons to participate in the valence cycles of Co(II)/Co(III) and Mo(IV)/Mo(VI) to boost the catalytic reduction of Pb(II). Specifically, Co(II) transferred a part of electrons to Mo(VI), promoting the formation of Mo(IV). Co(II) and Mo(IV), as the electron-rich sites, providing electrons to Pb(II), further accelerating the conversion of Pb(II) into Pb(0). SIGNIFICANCE: In the process of detecting Pb(II), the CoMoO4 structures under different temperatures have distinct content of electron-rich sites Co(II) and Mo(IV). α-CoMoO4 (800 °C), with the highest content are benefited to detect Pb(II). This work is conducive to understanding the effect of the changes of active sites resulting from crystal transformation on the electrocatalytic performance, and provides a way to construct sensitive electrochemical interfaces of distinct active sites.

In-situ precipitation zero-valent Co on Co2VO4 to activate oxygen vacancies and enhance bimetallic ions redox for efficient detection toward Hg(II).

Despite the widespread utilization of variable valence metals in electrochemistry, it is still a formidable challenge to enhance the valence conversion efficiency to achieve excellent catalytic activity without introducing heterophase elements. Herein, the in-situ precipitation of Co particles on Co2VO4 not only enhanced the concentration of oxygen vacancies (Ov) but also generated a greater number of low-valence metals, thereby enabling efficient reduction towards Hg(II). The electroanalysis results demonstrate that the sensitivity of Co/Co2VO4 towards Hg(II) was measured at an impressive value of 1987.74 µA µM-1 cm-2, significantly surpassing previously reported results. Further research reveals that Ov acted as the main adsorption site to capture Hg(II). The redox reactions of Co2+/Co3+ and V3+/V4+ played a synergistic role in the reduction of Hg(II), accompanied by the continuous supply of electrons from zero-valent Co to expedite the valence cycle. The Co/Co2VO4/GCE presented remarkable selectivity towards Hg(II), with excellent stability, reproducibility, and anti-interference capability. The electrode also exhibited minimal sensitivity fluctuations towards Hg(II) in real water samples, underscoring its practicality for environmental applications. This study elucidates the mechanism underlying the surface redox reaction of metal oxides facilitated by zero-valent metals, providing us with new strategies for further design of efficient and practical sensors.

Phosphorus-doped synergy of phase change in heterogeneous catalysts of NiS-NiS2 for efficient electrocatalysis of Pb(II).

A fundamental understanding of the electroanalytical activity of transition metal sulfide electrocatalysts, especially the origin of the electrocatalytic reactivity on the surface sites of heterostructures with multiple crystalline phases, is essential for the design of low-cost and highly efficient nonprecious metal electrocatalysts for further scientific and technological achievements. Herein, we injected P into NiS and occupied the S sites through a doping strategy. The redistributed electronic structure induced the construction of heterostructures, which significantly improved the structure and chemical state of electrochemically inert NiS. The phase-change mechanism between NiS and NiS2 synergistically catalyzes Pb(II), while the P and S sites jointly lose electrons. Moreover, the constructed heterojunction sensor shows the a sensitivity of 83.43 µA µM-1 to Pb(II) with a theoretical limit of detection of 48 nM, as well as excellent stability, reproducibility, and anti-interference ability. The accurate detection in real water further reveals the potential of this sensor for practical applications. This study provides a guiding strategy for improving electrochemically inert materials to design highly active electrocatalytic interfaces, which has important implications for the development of highly efficient electrode-sensitive materials similar to precious metals to achieve accurate electrical analysis.

Revealing the solid-solution interface interference behaviors between Cu2+ and As(III) via partial peak area analysis of simulations and experiments.

The mutual interference in the sensing detection of heavy metal ions (HMIs) is considerably serious and complex. Besides, the co-existed ions may change the stripping peak intensity, shape and position of the target ion, which partly makes peak current analysis inaccurate. Herein, a promising approach of partial peak area analysis was proposed firstly to research the mutual interference. The interference between two species on their electrodeposition processes was investigated by simulating different kinetics parameters, including surface coverage, electro-adsorption, -desorption rate constant, etc. It was proved that the partial peak area is sensitive and regular to these interference kinetics parameters, which is favorable for distinctly identifying different interferences. Moreover, the applicability of the partial peak area analysis was verified on the experiments of Cu2+, As(III) interference at four sensing interfaces: glassy carbon electrode, gold electrode, Co3O4, and Fe2O3 nanoparticles modified electrodes. The interference behaviors between Cu2+ and As(III) relying on solid-solution interfaces were revealed and confirmed by physicochemical characterizations and kinetics simulations. This work proposes a new descriptor (partial peak area) to recognize the interference mechanism and provides a meaningful guidance for accurate detection of HMIs in actual water environment.

Generalizable Descriptors of Highly Sensitive Detection of As(III) over Transition-Metal Single Atoms: A Combined Density Function Theory and Gradient Boosting Regression Approach.

Traditional nanomodified electrodes have made great achievements in electrochemical stripping voltammetry of sensing materials for As(III) detection. Moreover, the intermediate states are complicated to probe because of the ultrashort lifetime and complex reaction conditions of the electron transfer process in electroanalysis, which seriously hinder the identification of the actual active site. Herein, the intrinsic interaction of highly sensitive analytical behavior of nanomaterials is elucidated from the perspective of electronic structure through density functional theory (DFT) and gradient boosting regression (GBR). It is revealed that the atomic radius, d-band center (εd), and the largest coordinative TM-N bond length play a crucial role in regulating the arsenic reduction reaction (ARR) performance by the established ARR process for 27 sets of transition-metal single atoms supported on N-doped graphene. Furthermore, the database composed of filtered intrinsic electronic structural properties and the calculated descriptors of the central metal atom in TM-N4-Gra were also successfully extended to oxygen evolution reaction (OER) systems, which effectively verified the reliability of the whole approach. Generally, a multistep workflow is developed through GBR models combined with DFT for valid screening of sensing materials, which will effectively upgrade the traditional trial-and-error mode for electrochemical interface designing.

[Pollution Characteristics of Microplastics in Sediments of Xiamen Bay Beach].

Microplastics widely exist in various environmental media and have become a global environmental problem. To investigate the pollution characteristics, deposition patterns, and influencing factors of microplastics in the sediments of bay beach, five typical beaches were selected in Xiamen Bay. According to the tidal variation, 0-10 cm, 10-20 cm, and 20-30 cm sediment column samples were collected in layers at the high tide line, middle tide line, and low tide line at the same time, and the characteristics of the horizontal and vertical distribution of microplastics in the beach sediments were studied. The results showed that the abundance of microplastics in 45 sediment samples in Xiamen Bay beach ranged from 39 to 260 n·kg-1, with an average abundance of (114±26) n·kg-1. The shapes of microplastics were mainly fibers, fragments, granules, and foams, with fibers making up the largest proportion. The main components were polyethylene terephthalate (PET), cellophane, and polyethylene (PE). The colors of microplastics included transparent, yellow, blue, black, white, etc. The average abundance of microplastics showed a certain pattern depending on the beach location, intertidal zone, and sampling depth. Moreover, the abundance and distribution of microplastics on the beach were affected by various natural and human factors such as waves, tides, shoreline shape, the number of tourists, and the cleaning of marine floating debris. These results aid the understanding of the distribution characteristics and sources of microplastics in beach sediments, provide a basis for the transport of microplastics from land to sea, and provide data support for the collection of sea floating garbage and shoreline garbage.

Median arcuate ligament syndrome with retroperitoneal haemorrhage: A case report.

BACKGROUND: Median arcuate ligament syndrome (MALS) is relatively rare and is due to extraluminal compression of the coeliac artery by the median arcuate ligament of the diaphragm. Here, we report a case of MALS found in a patient with abdominal pain and retroperitoneal haemorrhage for education and dissemination. CASE SUMMARY: This article describes a 46-year-old female patient who was admitted to our hospital with abdominal pain as her chief complaint. She had experienced no obvious symptoms but had retroperitoneal bleeding during the course of the disease. Contrast-enhanced computed tomography (CT) and noninvasive CT angiography (CTA) led to an initial misdiagnosis of pancreaticoduodenal artery aneurysm (PDAA) causing retroperitoneal hemorrhage. After intraoperative exploration and detailed analysis of enhanced CT and CTA images, a final diagnosis of MALS was made. The cause of the haemorrhage was bleeding from a branch of the gastroduodenal artery, not rupture of a PDAA. The prognosis of MALS combined with PDAA treated by laparoscopy and interventional therapy is still acceptable. The patient was temporarily treated by gastroduodenal suture haemostasis and was referred for further treatment. CONCLUSION: MALS is very rare and usually has postprandial abdominal pain, upper abdominal murmur, and weight loss. It is diagnosed by imaging or due to complications. When a patient has abdominal bleeding or PDAA, we should consider whether the patient has celiac trunk stenosis (MALS or other etiology). When abdominal bleeding is combined with an aneurysm, we generally think of aneurysm rupture and hemorrhage first, but it may also be collateral artery rupture and hemorrhage.

General Strategies to Construct Highly Efficient Sensing Interfaces for Metal Ions Detection from the Perspective of Catalysis.

Constructing high-effective electrode sensing interfaces has been considered an effective method for electrochemical detection toward heavy metal ions (HMIs). However, most research has been devoted to enhancing the stripping currents of HMIs by simply improving the adsorptive capacity and conductivity of the electrode modified materials, while lacking theoretical guidelines in fabricating catalytic sensing interfaces. Besides, the understanding of detection mechanisms is quite unscientific from the perspective of catalysis. This perspective summarizes five general strategies in designing highly efficient sensing interfaces in the recent five years, including modulating crystal phases, orientations and planes, defect engineering, ionic valence state cycle engineering, adsorption in situ catalysis strategy, and construction of atomic level catalytic active sites. What's more, the catalytic mechanisms for improving the signals of HMIs, such as boosting the electron transfer rates and conversion rates, lowering the energy barriers, etc., are introduced and emphasized. This study has a great significance in directionally controlling functionalized electrochemical sensors to achieve excellent sensitivity and selectivity in detecting environmental pollutants from the view of catalysis, and it also brings enlightenments and guidance to develop new electroanalytical methods.

In-situ electronic structure redistribution tuning of single-atom Mn/g-C3N4 catalyst to trap atomic-scale lead(II) for highly stable and accurate electroanalysis.

Constructing catalysts with simple structures, uniform effective sites, and excellent performance is crucial for understanding the reaction mechanism of target pollutants. Herein, the single-atom catalyst of Mn-intercalated graphitic carbon nitride (Mn/g-C3N4) was prepared. It was found that the intercalated Mn atoms acted as strong electron donors to effectively tune the electronic structure distribution of the in-situ N atoms, providing a large number of negative potential atomic-scale sites for catalytic reactions. In the detection, the in-situ N atom established an electron bridge for the transient electrostatic trapping of free Pb(II), which induced Pb-N-Mn coordination bonding. Even in g-C3N4-loaded Mn nanoparticles, the N atom was again confirmed to be the interaction site for coupling with Pb. And the MnII-N4-C/MnIV-N4-C cycle actively participated in the electrocatalysis of Pb(II) was confirmed. Moreover, Mn/g-C3N4 achieved highly stable and accurate detection for Pb(II) with a sensitivity of 2714.47 µA·µM-1·cm-2. And excellent reproducibility and specific detection of real water samples made the electrode practical. This study contributes to understanding the changes in the electronic structure of chemically inert substrates after single-atom intercalation and the interaction between contaminants and the microstructure of sensitive materials, providing a guiding strategy for designing highly active electrocatalytic interfaces for accurate electroanalysis.

Sensing Material-Dependent Interference of Multiple Heavy Metal Ions: Experimental and Simulated Thermodynamics Study on Cu(II), Cd(II), and As(III) Electroanalysis.

Interference among multiple heavy metal ions (HMIs) is a significant problem that must be solved in electroanalysis, which extremely restricts the practical popularization of electrochemical sensors. However, due to the limited exploration of the intrinsic mechanism, it is still difficult to confirm the influencing factors. In this work, a series of experimental and theoretical electroanalysis models have been established to investigate the electroanalysis results of Cu(II), Cd(II), As(III), and their mixtures, which were based on the simple structure and stable coordination of nickel single-atom catalysts. X-ray absorption spectroscopy and density functional theory calculations were used to reveal the underlying detection mechanism of the 50-fold boosting effect of Cu(II) on As(III) while Cd(II) inhibits As(III). Combining the application of the thermodynamic model and Fourier transform infrared reflection, the specific interaction of the nanomaterials and HMIs on the interface is considered to be the fundamental source of the interference. This work opens up a new way of thinking about utilizing the unique modes of interplay between nanomaterials and HMIs to achieve anti-interference intelligent electrodes in stripping analysis.

Noble-metal-free Fe3O4/Co3S4 nanosheets with oxygen vacancies as an efficient electrocatalyst for highly sensitive electrochemical detection of As(III).

The electrochemical method for highly sensitive determination of arsenic(III) in real water samples with noble-metal-free nanomaterials is still a difficult but significant task. Here, an electrochemical sensor driven by noble-metal-free layered porous Fe3O4/Co3S4 nanosheets was successfully employed for As(III) analysis, which was prepared via a facile two-step method involves a hydrothermal treatment and a subsequent sulfurization process. As expected, the electrochemical detection of As(III) in 0.1 M HAc-NaAc (pH 6.0) by square wave anodic stripping voltammetry (SWASV) with a considerable sensitivity of 4.359 µA/µg·L-1 was obtained, which is better than the commonly used noble metals modified electrodes. Experimental and characterization results elucidate the enhancement of As(III) electrochemical performance could be attributed to its nano-porous structure, the presence of oxygen vacancies and strong synergetic coupling effects between Fe3O4 and Co3S4 species. Besides, the Fe3O4/Co3S4 modified screen printed carbon electrode (Fe3O4/Co3S4-SPCE) shows remarkable stability and repeatability, valuable anti-interference ability and could be used for detection in real water samples. Consequently, the results confirm that as-prepared porous Fe3O4/Co3S4 nanosheets is identified as a promising modifier to detect As(III) in real sample analysis.

Intranasal vaccination with Listeria ivanovii as vector of Mycobacterium tuberculosis antigens promotes specific lung-localized cellular and humoral immune responses.

We have previously demonstrated that a recombinant Listeria ivanovii (LI) strain expressing the ESAT-6 or Ag85C protein of Mycobacterium tuberculosis (Mtb) as a tuberculosis (TB) vaccine candidates induced antigen-specific cellular immune responses after intravenous immunization of mice. However, whether such recombinant strains could induce desired immune responses in the lung, where TB infection occurs, is not clear. In this paper, C57BL/6 J mice were intranasally vaccinated with attenuated LIΔactAplcB-Rv3875 (Δ refers to gene deletion in the bacterial genome) or LIΔactAplcB-Rv0129c, the two vaccine candidates that utilize LI as an antigen delivery vector. Bacterial load in the target organs, histological changes in the infected organs, the percentage of specific cytokine-secreting T cells in the lung and spleen, IgG levels in the serum and secretory IgA (SIgA) levles in bronchoalveolar lavage (BAL) fluid were determined at specific days post inoculation (dpi). The results showed that both strains were mainly confined to the lung and were eliminated at 10 dpi. The histological damage caused by the infection in the lung was slight and recovered by day 5. Intranasal vaccination of the mice twice at an interval of 4 weeks notably elicited TB antigen-specific CD4+ and CD8+ T cell responses in the lung and SIgA secretion in the pulmonary mucosa, and significantly enhanced the percentage of double-functional CD8+ T cells (IFN-γ+ TNF-α+ CD8+). To our knowledge, this is the first report regarding the used of LI vector vaccines to induce promising lung-localized cellular and humoral immune responses by intranasal vaccination. These data suggest that LI could be a novel and promising live vector to construct an intranasal vaccine against respiratory diseases.

IgG plasma cells initiate changes in the protein C system in mouse ulcerative colitis through CD14+CD64+ macrophage activation.

BACKGROUND: Inhibition of the protein C system (PCS) might be one of the mechanisms of ulcerative colitis (UC). OBJECTIVES: The aim of the study was to explore the role of IgG plasma cells in changes in the PCS in UC. MATERIAL AND METHODS: Dextran sulfate sodium (DSS) was chosen to induce mouse UC. Inflammation was assessed using hematoxylin & eosin (H&E) staining and immunofluorescence. The profiling of colonic plasma cells and macrophages from colitis mice was analyzed with flow cytometry. After stimulation of macrophages with IgG type immune complex (IgG-IC), western blot was used to determine tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6) protein levels. After co-incubation of colonic mucosa microvascular endothelial cells (MVECs) with TNF-α or IL-6, mitogen-activated protein kinase (MAPK) expression was detected. RESULTS: The DSS-colitis mice showed higher inflammatory indexes (p < 0.05 or p < 0.01), accompanied by greater infiltration of CD38+IgG+ plasma cells (p < 0.01), CD14+CD64+ macrophages (p < 0.01) and IgG-IC than healthy mice. Enhancement of TNF-α and IL-6 protein expression was demonstrated in this subset of macrophages when stimulated by IgG-IC (p < 0.01). After MVECs were incubated with TNF-α or IL-6, the expression of ß-arrestin1, pP38 MAPK and pJNK MAPK exhibited an increase (p < 0.05 or p < 0.01), but downregulation of endothelial protein C receptor (EPCR) expression was observed (p < 0.05 or p < 0.01); this inhibition of EPCR expression was reversed by SB203580, SP600125 or U0126 (p < 0.05 or p < 0.01). In addition, changes in activated protein C (APC) presented results similar to those for EPCR expression (p < 0.05 or p < 0.01). CONCLUSIONS: These results reveal that the PCS is inhibited during UC processing. There is a possibility that the interaction between IgG plasma cells and CD14+CD64+ macrophages, as well as further secretion of cytokines from CD14+CD64+ macrophages by the formation and stimulation of IgG-IC, subsequently influence MVECs through the ß-arrestin-MAPK pathway. Enhancement of PCS activity may represent a novel approach for treating UC.

Changing the Blood Test: Accurate Determination of Mercury(II) in One Microliter of Blood Using Oriented ZnO Nanobelt Array Film Solution-Gated Transistor Chips.

The measurement of ultralow concentrations of heavy metal ions (HMIs) in blood is challenging. A new strategy for the determination of mercury ions (Hg2+ ) based on an oriented ZnO nanobelt (ZnO-NB) film solution-gated field-effect transistor (FET) chip is adopted. The FET chips are fabricated with ZnO-NB film channels with different orientations utilizing the Langmuir-Blodgett (L-B) assembly technique. The combined simulation and I-V behavior results show that the nanodevice with ZnO-NBs parallel to the channel has exceptional performance. The sensing capability of the oriented ZnO-NB film FET chips corresponds to an ultralow minimum detectable level (MDL) of 100 × 10-12 m in deionized water due to the change in the electrical double layer (EDL) arising from the synergism of the field-induced effect and the specific binding of Hg2+ to the thiol groups (-SH) on the film surface. Moreover, the prepared FET chips present excellent selectivity toward Hg2+ , excellent repeatability, and a rapid response time (less than 1 s) for various Hg2+ concentrations. The sensing performance corresponds to a low MDL of 10 × 10-9 m in real samples of a drop of blood.

Enhanced chemiresistive sensing performance of well-defined porous CuO-doped ZnO nanobelts toward VOCs.

Although the post-doping approach as a typical and effective method has been widely employed to improve the gas sensing performance of nanostructured metal oxides, it easily breaks their porous nanostructures. Herein a facile partial cation-exchange strategy combined with thermal oxidation has been developed to prepare porous CuO-doped ZnO nanobelts. Using ZnSe·0.5N2H4 nanobelts as the precursor template, Cu2Se-doped precursor nanobelts were obtained with Zn2+ cations partially exchanged by Cu2+ cations. After annealing in air, they are further oxidized into well-defined porous CuO-doped ZnO nanobelts. Through manipulating the amount of exchanged Cu2+ cations, the CuO-doping concentration can be precisely tuned. Based on the assembly approach and in situ thermal oxidation, a uniform and stable sensing film consisting of porous CuO-doped nanobelts was fabricated. Compared with pristine porous ZnO nanobelts, the as-prepared porous CuO-doped nanobelts with p-type CuO|n-type ZnO heterojunctions exhibited better sensing performance toward volatile organic compounds (VOCs). Especially for 3 at% CuO-doped porous ZnO nanobelts, the relative responses toward 100 ppm of ethanol, acetone and formaldehyde were greatly enhanced more than two, four and ten times, respectively. Due to the porous structure, they also displayed a fast response/recovery time. Finally, this enhanced sensing mechanism was discussed for porous CuO-doped ZnO nanobelts.

Size-tunable Ag nanoparticles sensitized porous ZnO nanobelts: controllably partial cation-exchange synthesis and selective sensing toward acetic acid.

Porous ZnO nanobelts sensitized with Ag nanoparticles have been prepared via a partial cation-exchange reaction assisted by a thermal oxidation treatment, employing ZnSe·0.5N2H4 nanobelts as precursors. After partially exchanged with Ag+ cations, the belt-like morphology of the precursors is still preserved. Continuously calcined in air, they are in situ transformed into Ag nanoparticles sensitized porous ZnO nanobelts. The size of the Ag nanoparticles can be tuned through manipulating the amount of exchanging Ag+ cations. Considering the porous and belt-like nanostructure, sensing characteristics of ZnO and the catalytic activity of Ag nanoparticles, the gas sensing performances of the as-prepared Ag nanoparticles sensitized porous ZnO nanobelts have been carefully investigated. The results indicate that Ag nanoparticles significantly enhance the sensing performances of porous ZnO nanobelts toward typical volatile organic compounds. Especially, a good selectivity has been demonstrated toward acetic acid gas with a low detection limit less than 1 ppm. Furthermore, they also display a good reproducibility with a short response/recovery time due to the thin, uniform and porous sensing film, which is fabricated with the assembled technique and in situ calcined approach. Finally, their sensing mechanism has been further discussed.

Respective roles of the mitogen-activated protein kinase (MAPK) family members in pancreatic stellate cell activation induced by transforming growth factor-ß1 (TGF-ß1).

Activated pancreatic stellate cells (PSCs) play a crucial role in the progression of pancreatic fibrosis. Transforming growth factor-ß (TGF-ß) is one of the strongest stimulator inducing fibrosis. The mitogen-activated protein kinase (MAPK) proteins (including ERK, JNK and p38 MAPK) are known to contribute to PSC activation and pancreatic fibrosis. Previous studies have identified PSC activation induced by TGF-ß1 is related to MAPK pathway, but the respective role of MAPK family members in PSC activation still unclear, and which family member may be the key mediator in mice PSC activation still controversial. In this study, we investigated the influence of different MAPK family member (JNK, ERK, and p38 MAPK) on mice PSC activation using an in vivo and in vitro model. The results showed p-JNK, p-ERK and p-p38 MAPK were all over-expressed in CP group, and p-JNK, p-ERK, and p-p38 MAPK were co-expressed with activated PSC. In vitro, TGF-ß1 induced JNK and ERK over-expression in PSCs. In contrast, p38 MAPK expression in PSC showed only a very weak increase. JNK- and ERK-specific inhibitors inhibited FN and α-SMA mRNA expression in PSCs, and a p38 MAPK inhibitor had no effect on PSC activation. These findings indicate that JNK and ERK were directly involved in the PSCs activation induced by TGF-ß1 and the development of pancreatic fibrosis. p38 MAPK participate in the progression of CP, but it does not respond to TGF-ß1 directly and may not be regarded as the target of TGF-ß1 induced PSC activation.

[Construction and Fluorescence Analysis of the Recombinant Listeria ivanovii Strain Expressing Green Fluorescent Protein].

OBJECTIVE: Constructing the recombinant Listeria ivanovii strain expressing green fluorescent protein to provide an important tool for study of Listeria ivanovii. METHODS: The promoter of Listeria monocytogenes Listeriolysin O (phly) and the green fluorescent protein (GFP) gene were fused by SOEing PCR,and then ligated the fusion gene into plasmid pCW to result in recombinant plasmid pCW-phly-GFP. Recombinant plasmid was electroporated into Listeria ivanovii,and fluorescence microscope was used to analyze the expression of GFP. To observe the stability of recombinant plasmid and the stable expression of GFP in Listeria ivanovii,bacteria were cultured in the BHI broth with or without erythromycin for several generations. The stability of recombinant plasmid pCW-phly-GFP and fluorescent protein in each generation of bacteriawas studied by extracting plasmids and observing fluorescence. RESULTS: The exactness of recombinant plasmid pCW-phly-GFP was confirmed with restrictive endonuclease assay and sequence analysis. Under the fluorescence microscope,the green fluorescence was obvious in Listeria ivanovii carried with pCW-phly-GFP. The recombinant plasmid pCW-phly-GFP was stable in Listeria ivanovii and the GFP kept expressing in a high level under the pressure of erythromycin. CONCLUSION: The prokaryotic expression plasmid pCW-phly-GFP containing GFP gene was successfully constructed. Listeria ivanovii carried with the plasmid efficiently expressed GFP. This research provides an important tool for further study of Listeria ivanovii as a vaccine carrier.

Anti-inflammatory effect of cannabinoid agonist WIN55, 212 on mouse experimental colitis is related to inhibition of p38MAPK.

AIM: To investigate the anti-inflammatory effect and the possible mechanisms of an agonist of cannabinoid (CB) receptors, WIN55-212-2 (WIN55), in mice with experimental colitis, so as to supply experimental evidence for its clinical use in future. METHODS: We established the colitis model in C57BL/6 mice by replacing the animals' water supply with 4% dextran sulfate sodium (DSS) for 7 consecutive days. A colitis scoring system was used to evaluate the severity of colon local lesion. The plasma levels of proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6), and the myeloperoxidase (MPO) activity in colon tissue were measured. The expressions of cannabinoid receptors, claudin-1 protein, p38 mitogen-activated protein kinase (p38MAPK) and its phosphorylated form (p-p38) in colon tissue were determined by immunohistochemistry and Western blot. In addition, the effect of SB203580 (SB), an inhibitor of p38, was investigated in parallel experiments, and the data were compared with those from intervention groups of WIN55 and SB alone or used together. RESULTS: The results demonstrated that WIN55 or SB treatment alone or together improved the pathological changes in mice with DSS colitis, decreased the plasma levels of TNF-α, and IL-6, and MPO activity in colon. The enhanced expression of claudin-1 and the inhibited expression of p-p38 in colon tissues were found in the WIN55-treated group. Besides, the expression of CB1 and CB2 receptors was enhanced in the colon after the induction of DSS colitis, but reduced when p38MAPK was inhibited. CONCLUSION: These results confirmed the anti-inflammatory effect and protective role of WIN55 on the mice with experimental colitis, and revealed that this agent exercises its action at least partially by inhibiting p38MAPK. Furthermore, the results showed that SB203580, affected the expression of CB1 and CB2 receptors in the mouse colon, suggesting a close linkage and cross-talk between the p38MAPK signaling pathway and the endogenous CB system.

[A Point Raman Scanning Method for Rapidly Detection of Spinach Quality and Safety Parameters].

According to actual market demand for nondestructive detection of vegetables quality and safety, combined with the heterogeneity of quality and safety parameters such as pesticide residues on leaf vegetables surface and to realize the automatic point scanning for the whole leaf vegetables samples, a suction device based on laboratory (self-designed) Raman spectroscopy hardware and a GUI application software based on the LabVIEW development platform were developed. This system can test the Raman spectroscopy of the whole spinach including the automatic collection, display and storage of the Raman signal of all the scanned points by set up different scan step. A new method to remove the Raman spectrum background was proposed based on data replacement with linear equation at the range of threshold spectrum on both sides of the effective peaks according to the characteristics of spinach original spectra. Its principle is to determine the starting position of linear fitting by judging whether there is trough on both sides of the crest, and then to generate and replace the original spectra data in peak position through the linear fitting equation. Spinach samples were used for the experiment showed that the chlorophyll content and distribution of chlorpyrifos pesticide residue on each scanning point can be obtained after scanning. Therefore, the point scanning Raman system could improve detection accuracy of the quality and safety parameters for the non-uniform samples effectively.