Dirac cone in α-graphdiyne: a first-principles study

We investigate the Dirac cone in α-graphdiyne, which is a predicted flat one-atom-thick allotrope of carbon using first-principles calculations. α-graphdiyne is derived from graphene where two acetylenic linkages (-C ≡C-) are inserted into the single bonds (-C-C-). Thus, α-graphdiyne possesses a larger lattice constant which subsequently affects its electronic properties. Band structures show that α-graphdiyne exhibits similar Dirac points and cone to graphene. Further, the tight-binding method is used to exploit the linear dispersion in the vicinity of Dirac points. Thanks to the larger lattice constant, α-graphdiyne yields a lower Fermi velocity, which might make itself an ideal material to serve the anomalous integer quantum Hall effect.     

Low temperature-fired Ni-Cu-Zn ferrite nanoparticles through auto-combustion method for multilayer chip inductor applications

Ferrite nanoparticles of basic composition Ni_0.7-xZn_xCu_0.3Fe₂O₄ (0.0 ≤ x ≤ 0.2, x = 0.05) were synthesized through auto-combustion method and were characterized for structural properties using X-ray diffraction [XRD], scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy [FT-IR]. XRD analysis of the powder samples sintered at 600°C for 4 h showed the cubic spinel structure for ferrites with a narrow size distribution from 28 to 32 nm. FT-IR showed two absorption bands (v₁ and v₂) that are attributed to the stretching vibration of tetrahedral and octahedral sites. The effect of Zn doping on the electrical properties was studied using dielectric and impedance spectroscopy at room temperature. The dielectric parameters (ε'', ε″, tanδ, and σ_ac) show their maximum value for 10% Zn doping. The dielectric constant and loss tangent decrease with increasing frequency of the applied field. The results are explained in the light of dielectric polarization which is similar to the conduction phenomenon. The complex impedance shows that the conduction process in grown nanoparticles takes place predominantly through grain boundary volume.PACS: 75.50.Gg; 78.20; 77.22.Gm.     

Co-Incubation with PPARβ/δ Agonists and Antagonists Modeled Using Computational Chemistry: Effect on LPS Induced Inflammatory Markers in Pulmonary Artery

Peroxisome proliferator activated receptor beta/delta (PPARβ/δ) is a nuclear receptor ubiquitously expressed in cells, whose signaling controls inflammation. There are large discrepancies in understanding the complex role of PPARβ/δ in disease, having both anti- and pro-effects on inflammation. After ligand activation, PPARβ/δ regulates genes by two different mechanisms; induction and transrepression, the effects of which are difficult to differentiate directly. We studied the PPARβ/δ-regulation of lipopolysaccharide (LPS) induced inflammation (indicated by release of nitrite and IL-6) of rat pulmonary artery, using different combinations of agonists (GW0742 or L−165402) and antagonists (GSK3787 or GSK0660). LPS induced release of NO and IL-6 is not significantly reduced by incubation with PPARβ/δ ligands (either agonist or antagonist), however, co-incubation with an agonist and antagonist significantly reduces LPS-induced nitrite production and Nos2 mRNA expression. In contrast, incubation with LPS and PPARβ/δ agonists leads to a significant increase in Pdk−4 and Angptl−4 mRNA expression, which is significantly decreased in the presence of PPARβ/δ antagonists. Docking using computational chemistry methods indicates that PPARβ/δ agonists form polar bonds with His287, His413 and Tyr437, while antagonists are more promiscuous about which amino acids they bind to, although they are very prone to bind Thr252 and Asn307. Dual binding in the PPARβ/δ binding pocket indicates the ligands retain similar binding energies, which suggests that co-incubation with both agonist and antagonist does not prevent the specific binding of each other to the large PPARβ/δ binding pocket. To our knowledge, this is the first time that the possibility of binding two ligands simultaneously into the PPARβ/δ binding pocket has been explored. Agonist binding followed by antagonist simultaneously switches the PPARβ/δ mode of action from induction to transrepression, which is linked with an increase in Nos2 mRNA expression and nitrite production.     

ROS-Scavengers,Osmoprotectants and Violaxanthin De-Epoxidation in Salt-Stressed Arabidopsis thaliana with Different Tocopherol Composition

To determine the role of α- and γ-tocopherol (TC), this study compared the response to salt stress (200 mM NaCl) in wild type (WT) Arabidopsis thaliana (L.) Heynh. And its two mutants: (1) totally TC-deficient vte1; (2) vte4 accumulating γ-TC instead of α-TC; and (3) tmt transgenic line overaccumulating α-TC. Raman spectra revealed that salt-exposed α-TC accumulating plants were more flexible in regulating chlorophyll, carotenoid and polysaccharide levels than TC deficient mutants, while the plants overaccumulating γ-TC had the lowest levels of these biocompounds. Tocopherol composition and NaCl concentration affected xanthophyll cycle by changing the rate of violaxanthin de-epoxidation and zeaxanthin formation. NaCl treated plants with altered TC composition accumulated less oligosaccharides than WT plants. α-TC deficient plants increased their oligosaccharide levels and reduced maltose amount, while excessive accumulation of α-TC corresponded with enhanced amounts of maltose. Salt-stressed TC-deficient mutants and tmt transgenic line exhibited greater proline levels than WT plants, lower chlorogenic acid levels, and lower activity of catalase and peroxidases. α-TC accumulating plants produced more methylated proline- and glycine- betaines, and showed greater activity of superoxide dismutase than γ-TC deficient plants. Under salt stress, α-TC demonstrated a stronger regulatory effect on carbon- and nitrogen-related metabolites reorganization and modulation of antioxidant patterns than γ-TC. This suggested different links of α- and γ-TCs with various metabolic pathways via various functions and metabolic loops.     

Enzymatic Properties of Populus α- and β-NAD-ME Recombinant Proteins

Plant mitochondrial NAD-malic enzyme (NAD-ME), which is composed of α- and β-subunits in many species, participates in many plant biosynthetic pathways and in plant respiratory metabolism. However, little is known about the properties of woody plant NAD-MEs. In this study, we analyzed four NAD-ME genes (PtNAD-ME1 through PtNAD-ME4) in the genome of Populus trichocarpa. PtNAD-ME1 and -2 encode putative α-subunits, while PtNAD-ME3 and -4 encode putative β-subunits. The Populus NAD-MEs were expressed in Escherichia coli cells as GST-tagged fusion proteins. Each recombinant GST-PtNAD-ME protein was purified to near homogeneity by glutathione-Sepharose 4B affinity chromatography. Milligram quantities of each native protein were obtained from 1 L bacterial cultures after cleavage of the GST tag. Analysis of the enzymatic properties of these proteins in vitro indicated that α-NAD-MEs are more active than β-NAD-MEs and that α- and β-NAD-MEs presented different kinetic properties (V_max, k_cat and k_cat/K_m). The effect of different amounts of metabolites on the activities of Populus α- and β-NAD-MEs was assessed in vitro. While none of the metabolites evaluated in our assays activated Populus NAD-ME, oxalacetate and citrate inhibited all α- and β-NAD-MEs and glucose-6-P and fructose inhibited only the α-NAD-MEs.     

β-Defensin 2 Ameliorates Lung Injury Caused by Pseudomonas Infection and Regulates Proinflammatory and Anti-Inflammatory Cytokines in Rat

An important member of the defensin family, β-defensin 2, is believed to play an important role in defense against foreign pathogens. In the present study, we constructed lentiviral vectors to express and knockdown β-defensin 2 in rat lungs. The results showed that the infection of β-defensin 2 overexpression lentivirus and β-defensin 2 shRNA effectively increased and suppressed the expression of β-defensin 2 in rat lung, respectively. The overexpression of β-defensin 2 mediated by the lentiviral vector protected lung from infection of Pseudomonas aeruginosa, but shRNA targeting β-defensin 2 aggregated the damage of lung. In addition, we also found that β-defensin 2 overexpression increased basal expression of anti-inflammatory cytokine such as IL-4, IL-10 and IL-13 and decreased levels of proinflammatory cytokines which include IL-1α, IL-1β, IL-5, IL-6, IL-8, IL-18, and TNF-α. Moreover, in the process of cytokine regulation, NF-κB pathway may be involved. Taken together, these data suggest that β-defensin 2 has protective effects against infection of Pseudomonas aeruginosa in rat and plays a role in inflammatory regulation by adjusting cytokine levels.     

Genetic Regulation of Tryptase Production and Clinical Impact: Hereditary Alpha Tryptasemia,Mastocytosis and Beyond

Tryptase is a serine protease that is predominantly produced by tissue mast cells (MCs) and stored in secretory granules together with other pre-formed mediators. MC activation, degranulation and mediator release contribute to various immunological processes, but also to several specific diseases, such as IgE-dependent allergies and clonal MC disorders. Biologically active tryptase tetramers primarily derive from the two genes TPSB2 (encoding β-tryptase) and TPSAB1 (encoding either α- or β-tryptase). Based on the most common gene copy numbers, three genotypes, 0α:4β, 1α:3β and 2α:2β, were defined as “canonical”. About 4–6% of the general population carry germline TPSAB1-α copy number gains (2α:3β, 3α:2β or more α-extra-copies), resulting in elevated basal serum tryptase levels. This condition has recently been termed hereditary alpha tryptasemia (HαT). Although many carriers of HαT appear to be asymptomatic, a number of more or less specific symptoms have been associated with HαT. Recent studies have revealed a significantly higher HαT prevalence in patients with systemic mastocytosis (SM) and an association with concomitant severe Hymenoptera venom-induced anaphylaxis. Moreover, HαT seems to be more common in idiopathic anaphylaxis and MC activation syndromes (MCAS). Therefore, TPSAB1 genotyping should be included in the diagnostic algorithm in patients with symptomatic SM, severe anaphylaxis or MCAS.     

The Effect of the Aerial Part of Lindera akoensis on Lipopolysaccharides (LPS)-Induced Nitric Oxide Production in RAW264.7 Cells

Four new secondary metabolites, 3α-((E)-Dodec-1-enyl)-4β-hydroxy-5β-methyldihydrofuran-2-one (1), linderinol (6), 4′-O-methylkaempferol 3-O-α-l-(4″-E-p-coumaroyl)rhamnoside (11) and kaempferol 3-O-α-l-(4″-Z-p-coumaroyl) rhamnoside (12) with eleven known compounds—3-epilistenolide D₁ (2), 3-epilistenolide D₂ (3), (3Z,4α,5β)-3-(dodec-11-ynylidene)-4-hydroxy-5-methylbutanolide (4), (3E,4β,5β)-3-(dodec-11-ynylidene)-4-hydroxy-5-methylbutanolide (5), matairesinol (7), syringaresinol (8), (+)-pinoresinol (9), salicifoliol (10), 4″-p-coumaroylafzelin (13), catechin (14) and epicatechin (15)—were first isolated from the aerial part of Lindera akoensis. Their structures were determined by detailed analysis of 1D- and 2D-NMR spectroscopic data. All of the compounds isolated from Lindera akoensis showed that in vitro anti-inflammatory activity decreases the LPS-stimulated production of nitric oxide (NO) in RAW 264.7 cell, with IC₅₀ values of 4.1–413.8 μM.     

Molecular Characterization and Expression Analyses of the Complement Component C8α, C8β and C9 Genes in Yellow Catfish (Pelteobagrus fulvidraco) after the Aeromonas hydrophila Challenge

The complement components C8α, C8β and C9 have important roles in the innate immune system against invading microorganisms. Partial cDNA sequences of the Pf_C8α, Pf_C8β and Pf_C9 genes (Pf: abbreviation of Pelteobagrus fulvidraco) were cloned from yellow catfish. The Pf_C8α, Pf_C8β and Pf_C9 genes showed the greatest amino acid similarity to C8α (54%) and C8β (62%) of zebrafish and to C9 (52%) of grass carp, respectively. Ontogenetic expression analyses using real-time quantitative PCR suggested that the three genes may play crucial roles during embryonic and early larval development. The mRNA expressions of the three genes were all at the highest levels in liver tissue, and at lower or much lower levels in 16 other tissues, demonstrating that the liver is the primary site for the protein synthesis of Pf_C8α, Pf_C8β and Pf_C9. Injection of Aeromonas hydrophila led to up-regulation of the three genes in the spleen, head kidney, kidney, liver and blood tissues, indicating that the three genes may contribute to the host’s defense against invading pathogenic microbes. An increased understanding of the functions of the Pf_C8α, Pf_C8β and Pf_C9 genes in the innate immunity of yellow catfish will help enhance production of this valuable freshwater species.     

Ammonium fluoride-activated synthesis of cubic δ-TaN nanoparticles at low temperatures

Cubic delta-tantalum nitride (δ-TaN) nanoparticles were selectively prepared using a K₂TaF₇ + (5 + k) NaN₃ + kNH₄F reactive mixture (k being the number of moles of NH₄F) via a combustion process under a nitrogen pressure of 2.0 MPa. The combustion temperature, when plotted as a function of the number of moles of NH₄F used, was in the range of 850°C to 1,170°C. X-ray diffraction patterns revealed the formation of cubic δ-TaN nanoparticles at 850°C to 950°C when NH₄F is used in an amount of 2.0 mol (or greater) in the combustion experiment. Phase pure cubic δ-TaN synthesized at k = 4 exhibited a specific surface area of 30.59 m²/g and grain size of 5 to 10 nm, as estimated from the transmission electron microscopy micrograph. The role of NH₄F in the formation process of δ-TaN is discussed with regard to a hypothetical reaction mechanism.     

Cloning of the Lycopene β-cyclase Gene in Nicotiana tabacum and Its Overexpression Confers Salt and Drought Tolerance

Carotenoids are important pigments in plants that play crucial roles in plant growth and in plant responses to environmental stress. Lycopene β cyclase (β-LCY) functions at the branch point of the carotenoid biosynthesis pathway, catalyzing the cyclization of lycopene. Here, a β-LCY gene from Nicotiana tabacum, designated as Ntβ-LCY1, was cloned and functionally characterized. Robust expression of Ntβ-LCY1 was found in leaves, and Ntβ-LCY1 expression was obviously induced by salt, drought, and exogenous abscisic acid treatments. Strong accumulation of carotenoids and expression of carotenoid biosynthesis genes resulted from Ntβ-LCY1 overexpression. Additionally, compared to wild-type plants, transgenic plants with overexpression showed enhanced tolerance to salt and drought stress with higher abscisic acid levels and lower levels of malondialdehyde and reactive oxygen species. Conversely, transgenic RNA interference plants had a clear albino phenotype in leaves, and some plants did not survive beyond the early developmental stages. The suppression of Ntβ-LCY1 expression led to lower expression levels of genes in the carotenoid biosynthesis pathway and to reduced accumulation of carotenoids, chlorophyll, and abscisic acid. These results indicate that Ntβ-LCY1 is not only a likely cyclization enzyme involved in carotenoid accumulation but also confers salt and drought stress tolerance in Nicotiana tabacum.     

Alzheimer’s Disease—A Panorama Glimpse

The single-mutation of genes associated with Alzheimer’s disease (AD) increases the production of Aβ peptides. An elevated concentration of Aβ peptides is prone to aggregation into oligomers and further deposition as plaque. Aβ plaques and neurofibrillary tangles are two hallmarks of AD. In this review, we provide a broad overview of the diverses sources that could lead to AD, which include genetic origins, Aβ peptides and tau protein. We shall discuss on tau protein and tau accumulation, which result in neurofibrillary tangles. We detail the mechanisms of Aβ aggregation, fibril formation and its polymorphism. We then show the possible links between Aβ and tau pathology. Furthermore, we summarize the structural data of Aβ and its precursor protein obtained via Nuclear Magnetic Resonance (NMR) or X-ray crystallography. At the end, we go through the C-terminal and N-terminal truncated Aβ variants. We wish to draw reader’s attention to two predominant and toxic Aβ species, namely Aβ₄₋₄₂/ and pyroglutamate amyloid-beta peptides, which have been neglected for more than a decade and may be crucial in Aβ pathogenesis due to their dominant presence in the AD brain.     

Rosiglitasone and ROCK Inhibitors Modulate Fibrogenetic Changes in TGF-β2 Treated Human Conjunctival Fibroblasts (HconF) in Different Manners

Purpose: The effects of Rho-associated coiled-coil containing protein kinase (ROCK) 1 and 2 inhibitor, ripasudil hydrochloride hydrate (Rip), ROCK2 inhibitor, KD025 or rosiglitazone (Rosi) on two-dimension (2D) and three-dimension (3D) cultured human conjunctival fibroblasts (HconF) treated by transforming growth factor (TGFβ2) were studied. Methods: Two-dimension and three-dimension cultured HconF were examined by transendothelial electrical resistance (TEER, 2D), size and stiffness (3D), and the expression of the extracellular matrix (ECM) including collagen1 (COL1), COL4 and COL6, fibronectin (FN), and α-smooth muscle actin (αSMA) by quantitative PCR (2D, 3D) in the presence of Rip, KD025 or Rosi. Results: TGFβ2 caused a significant increase in (1) the TEER values (2D) which were greatly reduced by Rosi, (2) the stiffness of the 3D organoids which were substantially reduced by Rip or KD025, and (3) TGFβ2 induced a significant up-regulation of all ECMs, except for COL6 (2D) or αSMA (3D), and down-regulation of COL6 (2D). Rosi caused a significant up-regulation of COL1, 4 and 6 (3D), and down-regulation of COL6 (2D) and αSMA (3D). Most of these TGFβ2-induced expressions in the 2D and αSMA in the 3D were substantially inhibited by KD025, but COL4 and αSMA in 2D were further enhanced by Rip. Conclusion: The findings reported herein indicate that TGFβ2 induces an increase in fibrogenetic changes on the plane and in the spatial space, and are inhibited by Rosi and ROCK inhibitors, respectively.     

Investigation of the Antiproliferative Properties of Natural Sesquiterpenes from Artemisia asiatica and Onopordum acanthium on HL-60 Cells in Vitro

Plants and plant extracts play a crucial role in the research into novel antineoplastic agents. Four sesquiterpene lactones, artecanin (1), 3β-chloro-4α,10α-dihydroxy-1α,2α-epoxy-5α,7αH-guaia-11(13)-en-12,6α-olide (2), iso-seco-tanapartholide 3-O-methyl ether (3) and 4β,15-dihydro-3-dehydrozaluzanin C (4), were isolated from two traditionally used Asteraceae species (Onopordum acanthium and Artemisia asiatica). When tested for antiproliferative action on HL-60 leukemia cells, these compounds exhibited reasonable IC₅₀ values in the range 3.6–13.5 μM. Treatment with the tested compounds resulted in a cell cycle disturbance characterized by increases in the G1 and G2/M populations, while there was a decrease in the S phase. Additionally, 1–3 elicited increases in the hypodiploid (subG1) population. The compounds elicited concentration-dependent chromatin condensation and disruption of the membrane integrity, as revealed by Hoechst 33258–propidium staining. Treatment for 24 h resulted in significant increases in activity of caspases-3 and -9, indicating that the tested sesquiterpenes induced the mitochondrial pathway of apoptosis. The proapoptotic properties of the sesquiterpene lactones were additionally demonstrated withannexin V staining. Compounds 1 and 2 increased the Bax/Bcl-2 expression and decreased the expressions of CDK1 and cyclin B2, as determined at the mRNA level by means of RT-PCR. These experimental results indicate that sesquiterpene lactones may be regarded as potential starting structures for the development of novel anticancer agents.     

Controllable synthesis of flake-like Al-doped ZnO nanostructures and its application in inverted organic solar cells

Flake-like Al-doped ZnO (AZO) nanostructures including dense AZO nanorods were obtained via a low-temperature (100°C) hydrothermal process. By doping and varying Al concentrations, the electrical conductivity (σ) and morphology of the AZO nanostructures can be readily controlled. The effect of σ and morphology of the AZO nanostructures on the performance of the inverted organic solar cells (IOSCs) was studied. It presents that the optimized power conversion efficiency of the AZO-based IOSCs is improved by approximately 58.7% compared with that of un-doped ZnO-based IOSCs. This is attributed to that the flake-like AZO nanostructures of high σ and tunable morphology not only provide a high-conduction pathway to facilitate electron transport but also lead to a large interfacial area for exciton dissociation and charge collection by electrodes.     

Role of α2-Adrenoceptor Subtypes in Suppression of L-Type Ca2+ Current in Mouse Cardiac Myocytes

Sarcolemmal α2 adrenoceptors (α2-AR), represented by α2A, α2B and α2C isoforms, can safeguard cardiac muscle under sympathoadrenergic surge by governing Ca²⁺ handling and contractility of cardiomyocytes. Cardiomyocyte-specific targeting of α2-AR would provide cardiac muscle-delimited stress control and enhance the efficacy of cardiac malfunction treatments. However, little is known about the specific contribution of the α2-AR subtypes in modulating cardiomyocyte functions. Herein, we analyzed the expression profile of α2A, α2B and α2C subtypes in mouse ventricle and conducted electrophysiological antagonist assay evaluating the contribution of these isoforms to the suppression of L-type Ca²⁺ current (I_CaL). Patch-clamp electro-pharmacological studies revealed that the α2-agonist-induced suppression of I_CaL involves mainly the α2C, to a lesser extent the α2B, and not the α2A isoforms. RT-qPCR evaluation revealed the presence of adra2b and adra2c (α2B and α2C isoform genes, respectively), but was unable to identify the expression of adra2a (α2A isoform gene) in the mouse left ventricle. Immunoblotting confirmed the presence only of the α2B and the α2C proteins in this tissue. The identified α2-AR isoform-linked regulation of I_CaL in the mouse ventricle provides an important molecular substrate for the cardioprotective targeting.