The Dynamic Mechanical Properties and Damage Constitutive Model of Ultra-High-Performance Steel-Fiber-Reinforced Concrete (UHPSFRC) at High Strain Rates.

A high strain rate occurs when the strain rate exceeds 100 s-1. The mechanical behavior of materials at a high strain rate is different from that at middle and low strain rates. In order to study the dynamic compressive mechanical properties of ultra-high-performance steel-fiber-reinforced concrete (UHPSFRC) at high strain rates, an electro-hydraulic servo universal testing machine and a separate Hopkinson pressure bar (SHPB) with a diameter of 120 mm were used, respectively. A quasi-static compression test (strain rate 0.001 s-1) and impact compression test with a strain rate range of 90~200 s-1 were carried out to study the failure process, failure mode, and stress-strain curve characteristics of UHPSFRC at different strain rates and quantify the strain rate strengthening effect and fiber toughening effect. Based on the statistical damage theory and energy conversion principle, a dynamic damage constitutive model considering the effects of strain rate and fiber content was constructed. The results showed that the rate correlation of UHPSFRC and the fiber toughening properties showed a certain coupling competition mechanism. When the fiber content was less than 1.5%, with an increase in the steel fiber content, the crack initiation and propagation time of the specimen was extended, and the strain rate sensitivity gradually decreased. When the fiber content was 2%, the impact compressive strength of the specimen was optimal. Compared with UHPC, the dynamic increase factor (DIF) of UHPSFRC was significantly lower. The dynamic damage constitutive model established in this paper, considering the influence of strain rate and fiber content, has a good applicability and can describe the mechanical behavior of UHPSFRC at a high strain rate.

Nickel-Catalyzed Reductive Arylation of α-Bromo Sulfoxide.

A nickel-catalyzed cross-electrophile coupling of aryl iodides with α-bromo sulfoxide to access a diverse array of aryl benzyl sulfoxides has been discovered. These reactions occurred under mild conditions with excellent functional group tolerance so that optically enriched sulfoxides could be coupled with aryl iodides, generating corresponding sulfoxides with excellent stereochemical integrity. Furthermore, the scalability of this transformation was demonstrated. Initial mechanistic studies revealed that the reaction undergoes a radical pathway.

Predicting willingness to donate blood based on machine learning: two blood donor recruitments during COVID-19 outbreaks.

Machine learning methods are a novel way to predict and rank donors' willingness to donate blood and to achieve precision recruitment, which can improve the recruitment efficiency and meet the challenge of blood shortage. We collected information about experienced blood donors via short message service (SMS) recruitment and developed 7 machine learning-based recruitment models using PyCharm-Python Environment and 13 features which were described as a method for ranking and predicting donors' intentions to donate blood with a floating number between 0 and 1. Performance of the prediction models was assessed by the Area under the receiver operating characteristic curve (AUC), accuracy, precision, recall, and F1 score in the full dataset, and by the accuracy in the four sub-datasets. The developed models were applied to prospective validations of recruiting experienced blood donors during two COVID-19 pandemics, while the routine method was used as a control. Overall, a total of 95,476 recruitments via SMS and their donation results were enrolled in our modelling study. The strongest predictor features for the donation of experienced donors were blood donation interval, age, and donation frequency. Among the seven baseline models, the eXtreme Gradient Boosting (XGBoost) and Support vector machine models (SVM) achieved the best performance: mean (95%CI) with the highest AUC: 0.809 (0.806-0.811), accuracy: 0.815 (0.812-0.818), precision: 0.840 (0.835-0.845), and F1 score of XGBoost: 0.843 (0.840-0.845) and recall of SVM: 0.991 (0.988-0.994). The hit rate of the XGBoost model alone and the combined XGBoost and SVM models were 1.25 and 1.80 times higher than that of the conventional method as a control in 2 recruitments respectively, and the hit rate of the high willingness to donate group was 1.96 times higher than that of the low willingness to donate group. Our results suggested that the machine learning models could predict and determine the experienced donors with a strong willingness to donate blood by a ranking score based on personalized donation data and demographical details, significantly improve the recruitment rate of blood donors and help blood agencies to maintain the blood supply in emergencies.

Enhancing the interfacial stability of LiNi0.8Co0.15Al0.05O2 cathode materials by a surface-concentration gradient strategy.

Ni-rich LiNi0.8Co0.15Al0.05O2 materials have been successfully applied in electric vehicles due to the merits of high energy density which can meet the requirements for driving range. Nevertheless, the electrochemical performances of Ni-rich materials are limited by their structural instability. Herein, LiNi0.8Co0.15Al0.05O2 materials with the concentration-gradient structure of a Ni-rich core and a Co-rich surface were synthesized. The electrochemical results indicate that surface-concentration gradient LiNi0.8Co0.15Al0.05O2 provides improved electrochemical performance. It not only displays an initial Coulomb efficiency of 82.4%, and a capacity retention of 80.37% after 200 cycles at 25 °C, but also shows a capacity retention of 77.76% after 150 cycles at a high temperature of 55 °C. These excellent performances can be attributed to adjusting the distribution of Ni on the surface of the LiNi0.8Co0.15Al0.05O2 material, which inhibits the interfacial reaction between the material surface and electrolyte, lowers the consumption of active Li+ and decreases the interfacial film impedance. Moreover, less Ni content on the material surface is beneficial for reducing the formation of a NiO rock salt phase during the charging process and inhibits the surface structural evolution. The proposed method and detected mechanism will provide guidance for the design of cathode materials and their practical industrial applications.

Rab11B participates in erythrocyte storage lesion of under-collected whole blood.

BACKGROUND AND OBJECTIVES: The storage lesion of the red blood cell affects the life span of RBC and the quality of blood component. The elucidation of this mechanism is helpful to reduce the storage damage of RBC and improve the efficacy and safety of blood transfusion. The aim of this study was to discover the potential molecular mechanism of erythrocyte storage lesion with Under-collected whole blood (UC-WB) model. METHODS: The label-free MS/MS quantitative method was used to identify the differential proteins of erythrocyte membrane proteins and the difference of Rab11B, V-ATPase and plasma GDI2 protein expression were further verified by western blot at the end of blood storage. RESULTS: A total of 12 Rab proteins and 3 interacting effector proteins were identified among the membrane protein of normal WB and UC-WB, including 5 differential Rab proteins and 2 interacting effector proteins. Compared with normal WB, the expression of membrane Rab11B protein and ATP6V1B1/2 subunit of V-ATPases protein as well as the plasma GDI2 protein of UC-WB increased at the end of storage period. CONCLUSION: Rab protein might be related to RBC storage lesions, Rab11B participates in the RBC storage lesion through Rab11B/V-ATPases pathways.

Dynamic Mechanical Properties and Visco-Elastic Damage Constitutive Model of Freeze-thawed Concrete.

To study the dynamic mechanical characteristics and constitutive relation of concrete materials under freeze-thaw (FT) cycle conditions, C35 concrete was taken as the research object in this paper, and FT tests were carried out with a freeze-thaw range of -20-20 °C and a freeze-thaw frequency up to 50 times. By using the separated Hopkinson pressure bar (SHPB) system, impact compression tests of concrete specimens under different FT cycle actions were developed, then the dynamic fracture morphology, fracture block distribution, stress-strain curve, peak stress and other dynamic mechanical properties of concrete were analyzed, and the influence law of FT action and strain rate was obtained. Through introducing the freeze-thaw deterioration damage factor and the stress damage variable, the dynamic visco-elastic damage constitutive equation of freeze-thawed concrete was constructed based on component combination theory. Furthermore, the damage evolution process and mechanism of freeze-thawed concrete materials were revealed. The research results show that the dynamic mechanical properties of concrete under a freeze-thaw environment are the combined results of the freeze-thaw deterioration effect and the strain rate strengthening effect. The dynamic visco-elastic damage constitutive model established in this paper can effectively describe the dynamic mechanical properties of freeze-thawed concrete, and has the characteristics of few parameters and good effect. The stress damage evolution path of concrete goes backward with the increase of FT cycles and the development speed gradually slows down. The greater the difference in FT cycles, the greater the difference in stress damage path.

Research on the Fractal Characteristics and Energy Dissipation of Basalt Fiber Reinforced Concrete after Exposure to Elevated Temperatures under Impact Loading.

The fractal characteristics and energy dissipation of basalt fiber reinforced concrete (BFRC) with five kinds of fiber volume contents (0.0%, 0.1%, 0.2%, 0.3%, 0.4%) after exposure to different temperatures (20 °C, 200 °C, 400 °C, 600 °C, 800 °C) under impact loading were investigated by using a 50 mm diameter split Hopkinson pressure bar (SHPB) apparatus. Scale-mass distribution rules and fractal dimension characteristics of fragments were studied based on the screening statistical method and the fractal theory. Furthermore, the relationship between the energy consumption density and the fractal dimension of fragments was established, and the effects of fiber content, temperature and impact velocity on fractal dimension and absorption energy were analyzed. The results show that the crushing severity of fragments and fractal dimension increase with the impact velocity under the same fiber content. The energy consumption density increases first and then decreases with increasing fiber content, and also decreases with increasing temperature. When the temperature and fiber content remain unchanged, the energy consumption density increases linearly with the increasing fractal dimension, and under the same impact velocity and temperature, there is no obvious linear relationship between energy consumption density and fractal dimension.

Research on Fractal Characteristics and Energy Dissipation of Concrete Suffered Freeze-Thaw Cycle Action and Impact Loading.

In order to study the fractal characteristics and energy dissipation of concrete suffered freeze-thaw cycle actions and impact loading, C35 concrete was taken as the research object in this paper, and freeze-thaw cycle tests were carried out with a freeze-thaw range of -20 °C~20 °C and a freeze-thaw frequency of 0~50 times. The degradation characteristics of concrete material and the variation rules of basic physical parameters under various freeze-thaw cycle conditions were obtained consequently. By using the SHPB (separated Hopkinson pressure bar) test device, impact compression tests of concrete specimens under different freeze-thaw cycle actions were developed, then the process of impact crushing and the mechanism of damage evolution were analyzed. Based on the screening statistical method and the fractal theory, the scale-mass distribution rules and fractal dimension characteristics of crushing blocks are investigated. Furthermore, the absorption energy, fracture energy and block kinetic energy of concrete under different conditions were calculated according to the energy dissipation principle of SHPB test. The relationship between the energy consumption density and the fractal dimension of fragments was established, and the coupling effect mechanism of freeze-thaw cycle action and strain rate effect on the fractal characteristics and energy consumption was revealed additionally. The research results show that the concrete under different freeze-thaw cycle conditions and impact loading speeds has fractal properties from the microscopic damage to the macroscopic fracture. The energy dissipation is intrinsically related to the fractal characteristics, and the energy consumption density increases with the increase of the fractal dimension under a certain freeze-thaw cycle condition. When at a certain loading speed, with the growth of freeze-thaw cycles, the energy consumption density reduces under the same fractal dimension, while the fractal dimension improves under the same energy consumption density.

CRISPR-Cas13a Nanomachine Based Simple Technology for Avian Influenza A (H7N9) Virus On-Site Detection.

It is urgent to find an avian influenza A H7N9 detection simple method which is suitable for on-site detection. The Cas13a protein just likes a nanomachine, when specifically bound to target RNA by single-stranded RNA (crRNA), changes its protein structure and produces RNase activity, which degrades RNA non-specifically. Harnessing Cas13a, the paper aims to establish an underlying on-site H7N9 virus nucleic acid detection method. LwCas13a protein nanomachine was expressed in a prokaryotic expression system and purified by nickel column. In vitro transcribed RNA of H7N9 HA gene has been used as a target, to design a specific crRNA. The activity of Cas13a was verified with a single-stranded RNA-bound fluorescent group and a quenching fluorophore as signals. Using Cas13a, a room temperature H7N9 detection system was established. Detection of 1 nm of single-stranded RNA can be done within 5 min. When combined with the RT-RPA and T7 transcription system at room temperature, the detection limits of HA and NA are 1 fM and the reaction time is 50 min. Excellent specificity was achieved by comparison with subtype viruses such as H1N1 and H5N1. The rapid detection method based on CRISPR-Cas13a nanomachine H7N9 has been successfully established, which can detect H7N9 quickly and specifically. In the future, it can be quickly detected in the field with portable fluorescence detector.

Integration of Nucleic Acid Extraction Protocol with Automated Extractor for Multiplex Viral Detection.

The isolation of nucleic acids (NA) is the preliminary step to carry out genetic studies and DNA biosensor development. The presence of inhibitors in the purified NA interferes with the downstream application. These salts and other organic contaminations particularly challenge the analytical sensitivity of DNA biosensors. The detailed study was carried out to optimize the factors which might affect viral nucleic acid purification. The results suggested that 6 M guanidinium hydrochloride salt concentration was critical for NA isolation. The inverse relation has been found in the pH of the lysis buffer and quality and quantity of NA. The NA yield was relatively stable at pH 4­5. It has been observed that the use of carrier RNA was indispensable for viral genome isolation. The addition of ethanol to lysate in 1:1 ratio greatly improved NA recovery. The elution efficiency of DNase and RNase free water, 1× TE buffer and 1× PCR buffer was compared. The carrier RNA was best eluted in DNase and RNase free water and 1× TE buffer. It was further demonstrated that this method can be automatized for high throughput detection. A simple experiment was conducted to optimize the different parameters of an automated NA extractor to simultaneously extract HBV DNA and HCV RNA. The purified NA was successfully amplified in PCR and RT-PCR to verify the reliability of the established protocol. Thus a semi-automated system for the simultaneous detection of multiple viruses has been demonstrated.

Erythrocyte concentrates recovered from under-collected whole blood: experimental and clinical results.

BACKGROUND: Although periodic blood shortages are widespread in major Chinese cities, approximately 1 x 10(5) U of whole blood are discarded yearly because of under-collection. To reduce the wastage of acid citrate dextrose solution B (ACD-B) anticoagulated under-collected whole blood (UC-WB), this study was performed to elucidate the effect of extracellular pH and holding time on erythrocyte quality. Mannitol-adenine-phosphate (MAP) erythrocyte concentrates (UC-RBCs) were prepared with UC-WB to assess the safety and efficacy of this component. METHODS: The effect of the different extracellular pH levels and storage times on erythrocytes was assessed by fluorescent probes, SDS-PAGE electrophoresis, electron microscopy and spectroscopy. In vitro properties of 34 UC-RBCs that were prepared with UC-WB at different times after collection were analyzed and compared to normal RBCs during 35 days of storage. The results of transfusion with UC-RBCs and the incidence of adverse reactions in 49 patients were determined. RESULTS: 1) Low extracellular pH levels and long storage time induced increases in RBC fluorescence polarization and mean microviscosity, changes in membrane fluidity, band 1, 2 and 3 protein expression, and erythrocyte morphology. 2) During storage for 35 days, difference in between-subjects effects of K+, hemolysis and supernatant erythrocyte membrane protein (EMP) were statistically significant (P = 0.041, 0.007 and 0.002, respectively), while the differences between these parameters in the 4 h group and comparable controls were less significant. 3) Clinical data from 49 patients confirmed that transfusions with UC-RBCs were satisfactory with no adverse reactions. CONCLUSION: These results suggest that it is feasible to prepare RBCs with ACD-B anticoagulated UC-WB at a minimum of 66% volume of the labeled collection. It was effective and safe to transfuse the UC-RBCs prepared within 4 h after collection and stored within 7 days. The use of UC-WB would be a welcome addition to limited blood resources in China. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCTR-TRC-13003967.

Chemiluminescent labels released from long spacer arm-functionalized magnetic particles: a novel strategy for ultrasensitive and highly selective detection of pathogen infections.

Previously, the unique advantages provided by chemiluminescence (CL) and magnetic particles (MPs) have resulted in the development of many useful nucleic acid detection methods. CL is highly sensitive, but when applied to MPs, its intensity is limited by the inner filter-like effect arising from excess dark MPs. Herein, we describe a modified strategy whereby CL labels are released from MPs to eliminate this negative effect. This approach relies on (1) the magnetic capture of target molecules on long spacer arm-functionalized magnetic particles (LSA-MPs), (2) the conjugation of streptavidin-alkaline phosphatase (SA-AP) to biotinylated amplicons of target pathogens, (3) the release of CL labels (specifically, AP tags), and (4) the detection of the released labels. CL labels were released from LSA-MPs through LSA ultrasonication or DNA enzymolysis, which proved to be the superior method. In contrast to conventional MPs, LSA-MPs exhibited significantly improved CL detection, because of the introduction of LSA, which was made of water-soluble carboxymethylated ß-1,3-glucan. Detection of hepatitis B virus with this technique revealed a low detection limit of 50 fM, high selectivity, and excellent reproducibility. Thus, this approach may hold great potential for early stage clinical diagnosis of infectious diseases.

Specific-detection of clinical samples, systematic functional investigations, and transcriptome analysis reveals that splice variant MUC4/Y contributes to the malignant progression of pancreatic cancer by triggering malignancy-related positive feedback loops signaling.

BACKGROUND: MUC4 plays important roles in the malignant progression of human pancreatic cancer. But the huge length of MUC4 gene fragment restricts its functional and mechanism research. As one of its splice variants, MUC4/Y with coding sequence is most similar to that of the full-length MUC4 (FL-MUC4), together with alternative splicing of the MUC4 transcript has been observed in pancreatic carcinomas but not in normal pancreas. So we speculated that MUC4/Y might be involved in malignant progression similarly to FL-MUC4, and as a research model of MUC4 in pancreatic cancer. The conjecture was confirmed in the present study. METHODS: MUC4/Y expression was detected by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) using gene-specific probe in the clinic samples. The effects of MUC4/Y were observed by serial in vitro and in vivo experiments based on stable over-expressed cell model. The underlying mechanisms were investigated by sequence-based transcriptome analysis and verified by qRT-PCR, Western blot and enzyme-linked immunosorbent assays. RESULTS: The detection of clinical samples indicates that MUC4/Y is significantly positive-correlated with tumor invasion and distant metastases. Based on stable forced-expressed pancreatic cancer PANC-1 cell model, functional studies show that MUC4/Y enhances malignant activity in vitro and in vivo, including proliferation under low-nutritional-pressure, resistance to apoptosis, motility, invasiveness, angiogenesis, and distant metastasis. Mechanism studies indicate the novel finding that MUC4/Y triggers malignancy-related positive feedback loops for concomitantly up-regulating the expression of survival factors to resist adverse microenvironment and increasing the expression of an array of cytokines and adhesion molecules to affect the tumor milieu. CONCLUSIONS: In light of the enormity of the potential regulatory circuitry in cancer afforded by MUC4 and/or MUC4/Y, repressing MUC4 transcription, inhibiting post-transcriptional regulation, including alternative splicing, or blocking various pathways simultaneously may be helpful for controlling malignant progression. MUC4/Y- expression model is proven to a valuable tool for the further dissection of MUC4-mediated functions and mechanisms.

Elevation of MMP-9 and IDO induced by pancreatic cancer cells mediates natural killer cell dysfunction.

BACKGROUND: Natural killer (NK) cells play a key role in non-specific immune response in different cancers, including pancreatic cancer. However the anti-tumor effect of NK cells decreases during pancreatic cancer progression. The regulatory pathways by which NK cells facilitate tumor immune escape are unclear, therefore our purpose was to investigate the roles of the contributory factors. METHODS: NK cells isolated from fresh healthy peripheral blood were co-cultured with normal human pancreatic ductal cells hTERT-HPNE and human pancreatic cancer cell lines SW1990 and BxPc-3 in vitro. Then NK cell function was determined by Flow cytometric analysis of surface receptors and cytotoxic granules in NK cells, NK cell apoptosis and cytotoxicity, and Enzyme-linked immunosorbent assay of cytokines. Expression level of MMP-9, IDO and COX-2 in hTERT-HPNE and SW1990 cells were detected by quantitative RT-PCR. Statistical differences between data groups were determined by independent t-tests using SPSS 19.0 software. RESULTS: Our results showed that NK cell function was significantly downregulated following exposure to pancreatic cancer cells compared to normal pancreatic cells, as demonstrated by lower expressions of activating surface receptors (NKG2D, DNAM-1, NKp30 and NKp46) and cytotoxic granules (Perforin and Granzyme B); decreased secretion of cytokines (TNF-α and IFN-γ); and reduced cytotoxicity against myelogenous leukemia K562 cells. Further investigations revealed that MMP-9 and IDO may be implicated in SW1990 cell-induced NK cell dysfunction by facilitating tumor immune evasion. Blockade by TIMP-1 and/or 1-MT could partially restore NK function. CONCLUSIONS: Taken together, elevation of MMP-9 and IDO induced by pancreatic cancer cells mediates NK cell dysfunction. Our findings could contribute to the development of NK cell-based immunotherapy in patients with pancreatic cancer.

Pancreatic cancer counterattack: MUC4 mediates Fas-independent apoptosis of antigen-specific cytotoxic T lymphocyte.

Tumor-associated MUC4 mucin has considerable potential as an immunotherapy target for pancreatic cancer. In previous studies, we developed dendritic cell (DC) vaccines which elicited MUC4 antigen-specific cytotoxic T lymphocyte (MS-CTL) response against tumor cells in vitro. Due to the observation that MS-CTL apoptotic rate increased significantly when co-cultured with MUC4+ tumor cells compared with T2 cells, we investigated whether high expression levels of MUC4 in pancreatic cancer cells would have an effect on the significant increase of apoptosis rate of MS-CTLs. First, the adverse influence of regulatory T cells (Tregs) was eliminated by CD8+ T lymphocyte sorting before the induction of MS-CTLs. Then, we constructed clonal MUC4-knockdown HPAC pancreatic cancer sublines with different MUC4 expression for co-incubation system. By utilizing appropriate control to rule out the possible apoptosis-induced pathway of intrinsic activated cell-autonomous death (ACAD) and analogous antigen-dependent apoptosis of CTL (ADAC) in our study system, further analysis of the effect of MUC4 membrane-expression, supernatants and blockade of CTL surface Fas receptor on MS-CTL apoptosis was carried out. The results demonstrated that the level of MUC4 membrane expression strongly positively correlated with MS-CTL apoptosis and the influence of supernatants and Fas-blockade did not significantly correlate with MS-CTL apoptosis. This evidence suggested that there may be a novel counterattack pathway of pancreatic cancer cells, which is a MUC4-mediated, cell contact-dependent and Fas-independent process, to induce CTL apoptosis. Therefore, further exploration and understanding of the potential counterattack mechanisms is beneficial to enhance the efficacy of MUC4 specific tumor vaccines.

Transcription factor Ets-1 inhibits glucose-stimulated insulin secretion of pancreatic ß-cells partly through up-regulation of COX-2 gene expression.

Increased cyclooxygenase-2 (COX-2) expression is associated with pancreatic ß-cell dysfunction. We previously demonstrated that the transcription factor Ets-1 significantly up-regulated COX-2 gene promoter activity. In this report, we used the pancreatic ß-cell line INS-1 and isolated rat islets to investigate whether Ets-1 could induce ß-cell dysfunction through up-regulating COX-2 gene expression. We investigated the effects of ETS-1 overexpression and the effects of ETS-1 RNA interference on endogenous COX-2 expression in INS-1 cells. We used site-directed mutagenesis and a dual luciferase reporter assay to study putative Ets-1 binding sites in the COX-2 promoter. The effect of ETS-1 1 overexpression on the insulin secretion function of INS-1 cells and rat islets and the potential reversal of these effects by a COX-2 inhibitor were determined in a glucose-stimulated insulin secretion (GSIS) assay. ETS-1 overexpression significantly induces endogenous COX-2 expression, but ETS-1 RNA interference has no effect on basal COX-2 expression in INS-1 cells. Ets-1 protein significantly increases COX-2 promoter activity through the binding site located in the -195/-186 region of the COX-2 promoter. ETS-1 overexpression significantly inhibited the GSIS function of INS-1 cells and islet cells and COX-2 inhibitor treatment partly reversed this effect. These findings indicated that ETS-1 overexpression induces ß-cell dysfunction partly through up-regulation of COX-2 gene expression. Moreover, Ets-1, the transcriptional regulator of COX-2 expression, may be a potential target for the prevention of ß-cell dysfunction mediated by COX-2.

Long spacer arm-functionalized magnetic nanoparticle platform for enhanced chemiluminescent detection of hepatitis B virus.

A simple and cost-effective platform based on conjugating long spacer arms (LSA) onto magnetic nanoparticles (MNPs) was developed to enhance the chemiluminescent (CL) detection of pathogens. The modification method is both convenient and practical because it utilizes the commercially available macromolecule, carboxymethylated glucan (CMG), as the LSA. CMG-MNPS are designed to have low steric hindrance and high suspension properties, which allow for facile modification and hybridization reactions that enhance the CL sensitivity and detection. The infectious pathogen, hepatitis B virus (HBV) was selected for feasibility testing on this platform. The biotinylated amplicon of HBV, obtained by polymerase chain reaction (PCR), was hybridized to DNA probes functionalized on CMG-MNPs. The magnetic complexes were then incubated with streptavidin-alkaline phosphatase (SA-AP) to form linkages through biotin-streptavidin interactions. Finally, the magnetic complexes were mixed with 3-(2'-spiroadamantyl)-4-methoxy-4-(3"-phosphoryoxy)-phenyl-1,2-dioxetane (AMPPD) to generate CL signals that were proportional to the concentration of the HBV target. The detection of HBV with CMG-MNPs was more sensitive than that with the conventional carboxylated MNPs (CMNPs, succinic anhydride-modified MNPs). When optimized, the novel method showed high specificity and a detection limit of 0.5 pM. This new platform shows promise for the early clinical diagnosis of infectious diseases.

Solid-phase hybridization efficiency improvement on the magnetic nanoparticle surface by using dextran as molecular arms.

For reducing the steric hindrance and nonspecific binding of the target DNA, the dextran was used as molecular arms to be immobilized on the surface of magnetic nanoparticles (MNPs). Magnetic separation was used in preparation of dextran-MNPs (DMNPs). Aspartic acid and aminated DNA probe were successively modified on the dextran immobilized on the surface of MNPs. These probe-DMNPs were successfully applied to detect biotin-labeled PCR product of E. coli O157:H7 genome by hybridization. Then the complexes were bonded with streptavidin-modified alkaline phosphatase (ALP-SA). Finally the chemiluminescent signals were detected by adding 3-(2-spiroadamantane)-4-methoxy-4- (3-phosphoryloxy) phenyl-1,2-dioxetane (AMPPD). The results showed that this method had a good specificity, and higher sensitivity than that when only MNPs were used as solid carriers.

The ETS-Domain Transcription Factor Elk-1 Regulates COX-2 Gene Expression and Inhibits Glucose-Stimulated Insulin Secretion in the Pancreatic ß -Cell Line INS-1.

Cyclooxygenase-2 (COX-2) expression is associated with many aspects of physiological and pathological conditions, including pancreatic ß -cell dysfunction. Prostaglandin E2 (PGE2) production, as a consequence of COX-2 gene induction, has been reported to impair ß -cell function. The molecular mechanisms involved in the regulation of COX-2 gene expression are not fully understood. We previously demonstrated that transcription factor Elk-1 significantly upregulated COX-2 gene promoter activity. In this report, we used pancreatic ß -cell line (INS-1) to explore the relationships between Elk-1 and COX-2. We first investigated the effects of Elk-1 on COX-2 transcriptional regulation and expression in INS-1 cells. We thus undertook to study the binding of Elk-1 to its putative binding sites in the COX-2 promoter. We also analysed glucose-stimulated insulin secretion (GSIS) in INS-1 cells that overexpressed Elk-1. Our results demonstrate that Elk-1 efficiently upregulates COX-2 expression at least partly through directly binding to the -82/-69 region of COX-2 promoter. Overexpression of Elk-1 inhibits GSIS in INS-1 cells. These findings will be helpful for better understanding the transcriptional regulation of COX-2 in pancreatic ß -cell. Moreover, Elk-1, the transcriptional regulator of COX-2 expression, will be a potential target for the prevention of ß -cell dysfunction mediated by PGE2.

Transcriptional regulation of human MUC4 gene: identification of a novel inhibitory element and its nuclear binding protein.

The human mucin 4 (MUC4) is aberrantly expressed in pancreatic adenocarcinoma and tumor cell lines, while remaining undetectable in normal pancreas, indicating its important role in pancreatic cancer development. Although its transcriptional regulation has been investigated in considerable detail, some important elements remain unknown. The aim of the present study was to demonstrate the existence of a novel inhibitory element in the MUC4 promoter and characterize some of its binding proteins. By luciferase reporter assay, we located the inhibitory element between nucleotides -2530 and -2521 in the MUC4 promoter using a series of deletion and mutant reporter constructs. Electrophoretic mobility shift assay (EMSA) with Bxpc-3 cell nuclear extracts revealed that one protein or protein complex bind to this element. The proteins binding to this element were purified and identified as Yin Yang 1 (YY1) by mass spectrometry. Supershift assay and chromatin immunoprecipitation (ChIP) assay confirmed that YY1 binds to this element in vitro and in vivo. Moreover, transient YY1 overexpression significantly inhibited MUC4 promoter activity and endogenous MUC4 protein expression. In conclusion, we reported here a novel inhibitory element in the human MUC4 promoter. This provides additional data on MUC4 gene regulation and indicates that YY1 may be a potential target for abnormal MUC4 expression.