Vertically scanned laser sheet microscopy

Laser sheet microscopy is a widely used imaging technique for imaging the three-dimensional distribution of a fluorescence signal in fixed tissue or small organisms. In laser sheet microscopy, the stripe artifacts caused by high absorption or high scattering structures are very common, greatly affecting image quality. To solve this problem, we report here a two-step procedure which consists of continuously acquiring laser sheet images while vertically displacing the sample, and then using the variational stationary noise remover (VSNR) method to further reduce the remaining stripes. Images from a cleared murine colon acquired with a vertical scan are compared with common stitching procedures demonstrating that vertically scanned light sheet microscopy greatly improves the performance of current light sheet microscopy approaches without the need for complex changes to the imaging setup and allows imaging of elongated samples, extending the field of view in the vertical direction.This work was supported in part by the Bill and Melinda Gates Foundation, the National Basic Research Program of China (973 Program) under Grant No. 2011CB707700, the National Natural Science Foundation of China under Grant No. 81227901, 81027002, 61231004, and 81101095, the Fellowship for Young International Scientists of the Chinese Academy of Sciences under Grant No. 2010Y2GA03, and the Instrument Developing Project of the Chinese Academy of Sciences under Grant No. YZ201164. A. Arranz acknowledges support from the Marie Curie Intra-European Fellowship program IEF-2010-275137. J.R. acknowledges support from EC FP7 IMI project PREDICT-TB, the EC FP7 CIG grant HIGHTHROUGHPUT TOMO, and the Spanish MINECO project grant FIS2013-41802-R MESO-IMAGING

Automated identification and quantification of myocardial inflammatory infiltration in digital histological images to diagnose myocarditis

This study aims to develop a new computational pathology approach that automates the identification and quantification of myocardial inflammatory infiltration in digital HE-stained images to provide a quantitative histological diagnosis of myocarditis.898 HE-stained whole slide images (WSIs) of myocardium from 154 heart transplant patients diagnosed with myocarditis or dilated cardiomyopathy (DCM) were included in this study. An automated DL-based computational pathology approach was developed to identify nuclei and detect myocardial inflammatory infiltration, enabling the quantification of the lymphocyte nuclear density (LND) on myocardial WSIs. A cutoff value based on the quantification of LND was proposed to determine if the myocardial inflammatory infiltration was present. The performance of our approach was evaluated with a five-fold cross-validation experiment, tested with an internal test set from the myocarditis group, and confirmed by an external test from a double-blind trial group. An LND of 1.02/mm2 could distinguish WSIs with myocarditis from those without. The accuracy, sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) in the five-fold cross-validation experiment were 0.899 plus or minus 0.035, 0.971 plus or minus 0.017, 0.728 plus or minus 0.073 and 0.849 plus or minus 0.044, respectively. For the internal test set, the accuracy, sensitivity, specificity, and AUC were 0.887, 0.971, 0.737, and 0.854, respectively. The accuracy, sensitivity, specificity, and AUC for the external test set reached 0.853, 0.846, 0.858, and 0.852, respectively. Our new approach provides accurate and reliable quantification of the LND of myocardial WSIs, facilitating automated quantitative diagnosis of myocarditis with HE-stained images.Comment: 21 pages,5 figures,6 Tables, 25 reference

The Antimicrobial Peptide Mastoparan X Protects Against Enterohemorrhagic Escherichia coli O157:H7 Infection, Inhibits Inflammation, and Enhances the Intestinal Epithelial Barrier

Escherichia coli can cause intestinal diseases in humans and livestock, destroy the intestinal barrier, exacerbate systemic inflammation, and seriously threaten human health and animal husbandry development. The aim of this study was to investigate whether the antimicrobial peptide mastoparan X (MPX) was effective against E. coli infection. BALB/c mice infected with E. coli by intraperitoneal injection, which represents a sepsis model. In this study, MPX exhibited no toxicity in IPEC-J2 cells and notably suppressed the levels of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), myeloperoxidase (MPO), and lactate dehydrogenase (LDH) released by E. coli. In addition, MPX improved the expression of ZO-1, occludin, and claudin and enhanced the wound healing of IPEC-J2 cells. The therapeutic effect of MPX was evaluated in a murine model, revealing that it protected mice from lethal E. coli infection. Furthermore, MPX increased the length of villi and reduced the infiltration of inflammatory cells into the jejunum. SEM and TEM analyses showed that MPX effectively ameliorated the jejunum damage caused by E. coli and increased the number and length of microvilli. In addition, MPX decreased the expression of IL-2, IL-6, TNF-α, p-p38, and p-p65 in the jejunum and colon. Moreover, MPX increased the expression of ZO-1, occludin, and MUC2 in the jejunum and colon, improved the function of the intestinal barrier, and promoted the absorption of nutrients. This study suggests that MPX is an effective therapeutic agent for E. coli infection and other intestinal diseases, laying the foundation for the development of new drugs for bacterial infections

Rational Design of Nanocatalysts for Renewable Energy Conversion

Increasing fossil fuel consumption and CO2 emission have raised great concerns about our energy and environment future. In order to solve these problems, on the one hand, it is critical to develop alternative, renewable energy sources, such as fuel cell powered by H2, on the other hand, it is also important to reduce the existing CO2 into value-added products, such as fuels and fine chemicals. Electrocatalysis using nanomaterials plays an essential role in completing these two tasks by transforming the reactants into the target products efficiently along with the energy conversion process. The activity, stability, and selectivity of nanocatalysts highly depend on their structures, which require careful and rational design to achieve desired properties. Therefore, this dissertation focuses on the development of multiple effective strategies to improve the performance of different nanocatalysts for either fuel cell or CO2 reduction reaction (CO2RR) electrocatalysis.First, post-synthesis treatment has been recognized as a key step to tailor the catalytic behavior of Pt-based alloys. In the second chapter, we present the effects of catalyst processing on the electrocatalytic property of Pt-Ni nanoframes for cathodic oxygen reduction reaction (ORR) in fuel cell. The Pt-Ni nanoframes are made by corroding the Ni-rich phase from solid rhombic dodecahedral particles. Among the three different corrosion procedures, electrochemical corrosion leads to the highest initial specific activity by retaining more Ni in the nanoframes. However, the high activity gradually goes down in a subsequent stability test due to continuous Ni loss and concomitant surface reconstruction. In contrast, the best stability is achieved by a more-aggressive corrosion using oxidative nitric acid. Although the initial activity is compromised, this procedure imparts a less-defective surface, and thus, the specific activity drops by only 7% over 30,000 potential cycles. These results indicate a delicate trade-off between the activity and stability of Pt-Ni nanoframe electrocatalysts.Second, controlled synthesis of nanoparticles with optimal morphology and composition is crucial to promoting their catalytic performance. In the third chapter, we demonstrate the integration of highly open nanoframe morphology and catalytically active Pt-Co composition to develop Pt-Co nanoframes. Their ORR mass activity in acidic media is as high as 0.40 A mgPt-1 initially and 0.34 A mgPt-1 after 10,000 potential cycles at 0.95 V versus reversible hydrogen electrode (VRHE). Moreover, their mass activity for anodic methanol oxidation reaction (MOR) in alkaline fuel cell is up to 4.28 A mgPt-1 and is 4-fold higher than that of commercial Pt/C catalyst. Experimental studies indicate that the weakened binding of intermediate carbonaceous poisons contributes to the enhanced MOR behavior. More impressively, the Pt-Co nanoframes also show excellent stability under long-term testing, which could be attributed to the negligible electrochemical Co dissolution.Third, introducing a second material, such as the metal-organic framework (MOF), is a promising strategy to add catalytic functions beyond metal nanoparticles. In the fourth chapter, we demonstrate the combination of Pt-Ni nanoframe and zeolitic imidazolate framework-8 (ZIF-8), which is a special MOF, into an individually encapsulated frame-in-frame structure. Via surface functionalization, the Pt-Ni nanoframe is first embedded in ZIF-8 to achieve a single core-shell structure, as evidenced by the three-dimensional tomography. The growth trajectory of such frame-in-frame nanocomposite is tracked, revealing that ZIF-8 first nucleates in the solution, then attaches to the surface of the nanoframe, and finally grows to capture the entire nanoframe, enabling the one-in-one encapsulation. Next, by utilizing ZIF-67 as the sacrificial layer, the Pt-Ni nanoframe is further solely encased in ZIF-8 to form a single yolk-shell structure, which has a cavity between the core and the shell. The obtained frame-in-frame structures have potential applications in size-selective or tandem catalysis to produce fine chemicals.Fourth, long-range atomic ordering in nanocrystals holds the promise of unique catalytic properties for many reactions. In the fifth chapter, we report the preparation of Cu3Au intermetallic nanowires by using Cu@Au core-shell nanowires as the precursors. With appropriate Cu/Au stoichiometry, the Cu@Au core-shell nanowires are transformed into fully ordered Cu3Au nanowires under thermal annealing. Thermally-driven atomic diffusion, which is facilitated by the abundant twin boundaries, accounts for the ordering process. The resulting Cu3Au intermetallic nanowires have uniform and accurate atomic positioning in the crystal lattice, which enhances the nobility of Cu. No obvious copper oxides are observed in fully ordered Cu3Au nanowires after annealing in air at 200 oC, a temperature that is much higher than those observed in Cu@Au core-shell and pure Cu nanowires. The acquired Cu3Au intermetallic nanowires are promising candidates for either ORR or CO2RR electrocatalysis.Fifth, covalently bonded surface ligands often block the active metal sites and limit the reactivity of nanocluster catalysts. In the sixth chapter, we investigate the ligand removal process for Au25 nanoclusters using both thermal and electrochemical treatments, as well as its impact on the CO2 electroreduction to CO. The Au25 nanoclusters are synthesized with 2-phenylethanethiol as the capping agent and anchored on sulfur-doped graphene. The thiolate ligands can be readily removed under either thermal annealing at >180 oC or electrochemical biasing at <-0.5 VRHE. However, these ligand-removing conditions also trigger the structural evolution of Au25 nanoclusters concomitantly. The thermally and electrochemically treated Au25 nanoclusters show enhanced activity and selectivity for the electrochemical CO2-to-CO conversion than their pristine counterpart, which is attributed to the increased exposure of undercoordinated Au sites on the surface after ligand removal