Tailoring the carbon nanostructures grown on the surface of Ni-Al bimetallic nanoparticles in the gas phase

A gas-phase, one-step method for producing various aerosol carbon nanostructures is described. The carbon nanostructures can be selectively tailored with either straight, coiled, or sea urchin-like structures by controlling the size of Ni-Al bimetallic nanoparticles and the reaction temperature. The carbon nanostructures were grown using both conventional spray pyrolysis and thermal chemical vapor deposition. Bimetallic nanoparticles with catalytic Ni (guest) and non-catalytic Al (host) matrix were reacted with acetylene and hydrogen gases. At the processing temperature range of 650-800 °C, high concentration straight carbon nanotubes (S-CNTs) with a small amount of coiled carbon nanotubes (C-CNTs) can be grown on the surface of seeded bimetallic nanoparticle size <100 nm, resulting from consumption of the melting Al matrix sites; sea urchin-like carbon nanotubes (SU-CNTs) of small diameter (～10±4 nm) can be grown on the bimetallic nanoparticle size >100 nm, resulting from the significant size reduction of the available Ni sites due to thermal expansion of molten Al matrix sites without consumption of Al matrix. However, at the processing temperature range of 500-650 °C, C-CNTs can be grown on the bimetallic nanoparticle size <100 nm due to the presence of Al matrix in the bimetallic nanoparticles; SU-CNTs of large diameter (～60±13 nm) can also be grown on the bimetallic nanoparticle size >100 nm due to the isolation of Ni sites in the Al matrix.     

LRRK2 phosphorylates Snapin and inhibits interaction of Snapin with SNAP-25

Leucine-rich repeat kinase 2 (LRRK2) is a gene that, upon mutation, causes autosomal-dominant familial Parkinson''s disease (PD). Yeast two-hybrid screening revealed that Snapin, a SNAP-25 (synaptosomal-associated protein-25) interacting protein, interacts with LRRK2. An in vitro kinase assay exhibited that Snapin is phosphorylated by LRRK2. A glutathione-S-transferase (GST) pull-down assay showed that LRRK2 may interact with Snapin via its Ras-of-complex (ROC) and N-terminal domains, with no significant difference on interaction of Snapin with LRRK2 wild type (WT) or its pathogenic mutants. Further analysis by mutation study revealed that Threonine 117 of Snapin is one of the sites phosphorylated by LRRK2. Furthermore, a Snapin T117D phosphomimetic mutant decreased its interaction with SNAP-25 in the GST pull-down assay. SNAP-25 is a component of the SNARE (Soluble NSF Attachment protein REceptor) complex and is critical for the exocytosis of synaptic vesicles. Incubation of rat brain lysate with recombinant Snapin T117D, but not WT, protein caused decreased interaction of synaptotagmin with the SNARE complex based on a co-immunoprecipitation assay. We further found that LRRK2-dependent phosphorylation of Snapin in the hippocampal neurons resulted in a decrease in the number of readily releasable vesicles and the extent of exocytotic release. Combined, these data suggest that LRRK2 may regulate neurotransmitter release via control of Snapin function by inhibitory phosphorylation.     

Metabolic improvement and liver regeneration by inhibiting CXXC5 function for non-alcoholic steatohepatitis treatment

Non-alcoholic steatohepatitis (NASH) is a chronic liver disease that results from multiple metabolic disorders. Considering the complexity of the pathogenesis, the identification of a factor mediating the multiple pathogenic phenotypes of NASH will be important for treatment. In this study, we found that CXXC5, a negative feedback regulator of the Wnt/β-catenin pathway, was overexpressed with suppression of Wnt/β-catenin signaling and its target genes involved in hepatic metabolism in obese-NASH patients. Cxxc5^−/− mice were found to be resistant to NASH pathogenesis with metabolic improvements. KY19334, a small molecule that activates the Wnt/β-catenin pathway via interference of the CXXC5-Dvl interaction, reversed the overall pathogenic features of NASH as Cxxc5^−/− mice. The improvement in NASH by KY19334 is attributed to its regenerative effects through restorative activation of the suppressed Wnt/β-catenin signaling. Overall, the pronounced metabolic improvements with the stimulation of liver regeneration by interfering with the CXXC5-Dvl interaction provide a therapeutic approach for NASH.Subject terms: Metabolic syndrome, Metabolic syndrome, Regenerative medicine     

Ring opening of 2,5-didehydrothiophene: matrix photochemistry of C4H2S isomers

Irradiation (lambda > 254 nm) of matrix-isolated 2,5-diiodothiophene (10) gives rise to IR bands assigned to ethynylthioketene (6). Diethynyl sulfide (3), which would form in the process of retro-Bergman cyclization of the incipient 2,5-didehydrothiophene (4), is not detected. Under the same irradiation conditions, matrix-isolated diethynyl sulfide (3) rearranges to thioketene 6 and butatrienethione (5), the global minimum on C4H2S potential energy surface. The photochemical formation of thioketene 6 from either diyl 4 or sulfide 3 may be interpreted in line with a recent computational prediction on the thermal ring opening of diyl 4, which favors C-S bond cleavage, leading to 6, over C-C bond cleavage, leading to 3. Photolysis of matrix-isolated 3,4-thiophenedicarboxylic acid anhydride (11) enables the observation of the photoequilibration of three low-energy C4H2S isomers, butatrienethione (5), ethynylthioketene (6), and butadiynylthiol (7), via apparent [1,3]-hydrogen shifts.     

Genetic and expression alterations in association with the sarcomatous change of cholangiocarcinoma cells

Cholangiocarcinoma (CC) is an intrahepatic bile duct carcinoma with a high mortality rate and a poor prognosis. Sarcomatous change/epithelial mesenchymal transition (EMT) of CC frequently leads to aggressive intrahepatic spread and metastasis. The aim of this study was to identify the genetic alterations and gene expression pattern that might be associated with the sarcomatous change in CC. Previously, we established 4 human CC cell lines (SCK, JCK1, Cho-CK, and Choi-CK). In the present study, we characterized a typical sarcomatoid phenotype of SCK, and classified the other cell lines according to tumor cell differentiation (a poorly differentiated JCK, a moderately differentiated Cho-CK, and a well differentiated Choi-CK cells), both morphologically and immunocytologically. We further analyzed the genetic alterations of two tumor suppressor genes (p53 and FHIT) and the expression of Fas/FasL gene, well known CC-related receptor and its ligand, in these four CC cell lines. The deletion mutation of p53 was found in the sarcomatoid SCK cells. These cells expressed much less Fas/FasL mRNAs than did the other ordinary CC cells. We further characterize the gene expression pattern that is involved in the sarcomatous progression of CC, using cDNA microarrays that contained 18,688 genes. Comparison of the expression patterns between the sarcomatoid SCK cells and the differentiated Choi-CK cells enabled us to identify 260 genes and 247 genes that were significantly over-expressed and under-expressed, respectively. Northern blotting of the 14 randomly selected genes verified the microarray data, including the differential expressions of the LGALS1, TGFBI, CES1, LDHB, UCHL1, ASPH, VDAC1, VIL2, CCND2, S100P, CALB1, MAL2, GPX1, and ANXA8 mRNAs. Immunohistochemistry also revealed in part the differential expressions of these gene proteins. These results suggest that those genetic and gene expression alterations may be relevant to the sarcomatous change/EMT in CC cells.     

A selective determination of norepinephrine on the glassy carbon electrode modified with poly(ethylenedioxypyrrole dicarboxylic acid) nanofibers

A glassy carbon electrode modified with poly(3,4-ethylenedioxypyrrole-2,5-dicarboxylic acid) nanofibers (PEDOPA-NFs) was prepared for the determination of norepinephrine (NE) in phosphate buffer saline. The modified electrode demonstrated an improved sensitivity and selectivity toward the electrochemical detection of NE and could detect separately ascorbic acid (AA), uric acid (UA), and NE in their mixture. The separations of the oxidation peak potentials of NE–AA and NE–UA were 160 and 150 mV, respectively. Meanwhile, the modified electrode showed higher sensitivity and selectivity toward NE than dopamine and epinephrine. Using differential pulse voltammetry, the oxidation peak current of NE was found to be linearly dependent on its concentration within the range of 0.3–10 μM, and the detection limit of the NE oxidation current was 0.05 μM at a signal-to-noise ratio of 3. The PEDOPA-NFs promoted the electron transfer reaction of NE, while the PEDOPA-NFs, acting as a negatively charged linker, combined with the positively charged NE to induce NE accumulation in the NFs at pH under 7.4. However, the PEDOPA-NFs restrained the electrochemical response of the negatively charged AA and UA due to the electrostatic repulsion. The result indicates that the modified electrode can be used to determine NE without interference from AA and UA and selectively in the mixture of catecholamines.     

Laser-induced growth and reformation of gold and silver nanoparticles

The sizes, shapes, and growth rates of gold and silver nanoparticles stabilized with polyvinylpyrrolidone in water can be controlled by using picosecond laser pulses. The nucleation of small metal clusters formed with NaBH₄ addition to produce nanoparticles takes two months with aging but 30 min with laser irradiation. Laser pulses can also induce nanoparticles to have narrow size and shape distribution or to undergo aggregation into much larger particles. The latter process is more likely found when the metal is silver or the irradiation wavelength is short. Laser-induced growth and shape transformation processes are explained in terms of BH₄ ⁻ depletion, metal fusion, and electron ejection followed by disintegration.     

Numerical prediction of tip vortex cavitation behavior and noise considering nuclei size and distribution

The tip vortex cavitation behavior and sound generation were numerically analyzed. A numerical scheme combining Eulerian flow field computation and Lagrangian particle trace approach was applied to simulate tip vortex cavitation. Flow field was computed by using hybrid method which combines Reynolds-Averaged Navier-Stokes solver with Dissipation Vortex Model. The trajectory and behavior of each cavitation bubble were computed by Newton’s second law and Rayleigh-Plesset equation, respectively. According to nuclei population data, the cavitation nuclei were distributed and convected into the tip vortex flow. Calculated volume of the cavitation bubble and the trajectory were used as the input of cavitation bubble noise analysis. The relationship of cavitation inception, sound pressure level, and cavitation nuclei size was studied at several cavitation numbers. It was found that cavitation inception of smaller nuclei is more sensitive to the change of cavitation number and cavitation noise due to the cavitated smallest nuclei has the most influence on overall tip vortex cavitation noise.     

Proteomic applications of surface plasmon resonance biosensors: analysis of protein arrays

Proteomics is one of the most important issues in the post-genomic area, because it can greatly contribute to identifying protein biomarkers for disease diagnosis and drug screening. Protein array is a key technology for proteome researches and has been analyzed by various methods including fluorescence, mass spectrometry, atomic force microscopy and surface plasmon resonance (SPR). SPR biosensor is a promising technology in proteomics, since it has various advantages including real-time measurement of biomolecular interactions without labeling and the simple optical system for the device. SPR biosensors have a strong potential for analyzing proteomes by SPR imaging and SPR spectroscopic imaging, even though the challenge is to produce proteins on a proteomic scale.