3,881 research outputs found
Optimization of Cu(ll) extraction from aqueous solutions using soybean oil-based organic solvent by response surface methodology / Chang Siu Hua and Teng Tjoon Tow
No full textOrganic solvents are important liquids used to extract heavy metals from aqueous solutions in solvent extraction. A wide variety of organic solvents have been applied in this technique but most of them are petroleum-based (e.g. kerosene, hexane, toluene, chloroform, etc.) which are non-ecofriendly, non-renewable and expensive. Recently, vegetable oils have created a great deal of interest as greener replacement for the conventional organic solvents as alternative solvents in solvent extraction on account of their salient features such as non-volatility, non-flammability and biodegradability.
In our previous works, various vegetable oils like corn, canola, sunflower and soybean oils have been found to extract Cu(ll) effectively from aqueous solutions (Chang et al., 2010). In this work, optimization of factors (mixing time (t), extractant concentration, phase modifier concentration, inert salt concentration, organic to aqueous phase (0:A) ratio and equilibrium pH (pHeq)) affecting Cu(ll) extraction from aqueous solutions using a soybean oil-based organic solvent was conducted by a multivariate statistical technique, called Response Surface Methodology. The soybean oil-based organic solvent was composed of di-2-ethylhexylphosphoric acid (D2EHPA) (extractant) and tributylphosphate (TBP) (phase modifier) diluted in soybean oil (diluent). Factors that are influential to Cu(ll) extraction were first investigated in screening experiments based on a two fractional factorial design, followed by optimization of these factors in optimization experiments based on central composite design (CCD). A regression model correlating the response and factors was developed and its adequacy was examined. The optimum conditions for maximum Cu(ll) extraction were determined and the predicted and experimental percentage extraction obtained under the optimum conditions were compare
Cisplatin dose intensity correlates with outcome in patients with locally advanced head and neck squamous cell carcinoma receiving concurrent cisplatin based chemoradiation: a multi-institutional experience
No full textNatalia LL - artystka neoawangardowa
No full textThe paper shows Natalia Lach-Lachowicz (Natalia LL) as a neo avant-garde artist whose works in a specific maximalistic way are very close to the main currents of avant-garde trends: new mediality (photography), minimalism, conceptualism, performance, bodyart, pop-art, and feminist art. The author of the article concentrates mainly on the mutual influences of conceptualism, consumptionism, and feminism in Natalia LL’s works and pays attention to the emancipatory potential of her works of the seventies and the eighties
Energy flux in isotropic turbulence under large variations of external forcing
No full textWe investigate the response of energy flux in isotropic turbulence to step-function like perturbation in external forcing at large length scales. From both physical experiments and direct numerical simulations, we measured the evolution of the Eulerian velocity structure functions, such as , , before and after the perturbation in forcing. In both cases, we observed the cascade of the energy excess at large scales cascade through scales to the dissipative range, which can be used to study the dynamics of the cascade, and in particular, to estimate the relevant time scales
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Some rhetorical strategies in later nineteenth-century laboring-class poetry
No full textStructural and functional analysis of the pro-domain of human cathelicidin, LL-37
No full textCathelicidins form a family of small host defense peptides distinct from another class of cationic antimicrobial peptides, the defensins. They are expressed as large precursor molecules with a highly conserved pro-domain known as the cathelin-like domain (CLD). CLDs have high degrees of sequence homology to cathelin, a protein isolated from pig leukocytes and belonging to the cystatin family of cysteine protease inhibitors. In this report, we describe for the first time the X-ray crystal structure of the human CLD (hCLD) of the sole human cathelicidin, LL-37. The structure of hCLD, determined at 1.93 Å resolution, shows the cystatin-like fold and is highly similar to the structure of the CLD of the pig cathelicidin, protegrin-3. We assayed the in vitro antibacterial activities of hCLD, LL-37 and the precursor form, pro-cathelicidin (also known as hCAP18), and we found that the unprocessed protein inhibited the growth of Gramnegative bacteria with efficiencies comparable to the mature peptide, LL-37. In addition, the antibacterial activity of LL-37 was not inhibited by hCLD intermolecularly, since exogenously added hCLD had no effect on the bactericidal activity of the mature peptide. hCLD itself lacked antimicrobial function and did not inhibit the cysteine protease, cathepsin L. Our results contrast with previous reports of hCLD activity. A comparative structural analysis between hCLD and the cysteine protease inhibitor stefin A showed why hCLD is unable to function as an inhibitor of cysteine proteases. In this respect, the cystatin scaffold represents an ancestral structural platform from which proteins evolved divergently, with some losing inhibitory functions
The modulatory effect of TLR2 on LL-37-induced human mast cells activation
No full textThe sole and endogenous anti-microbial peptide LL-37 is a significant effector molecule in the innate host defense system. Apart from its broadly direct anti-microbial activity, the peptide also activates mast cell in respect of allergic diseases and inflammation. On the other hand, mast cell can be activated by Toll-like receptors (TLRs) which are at the center of innate immunity. It was the aim of the study to illustrate the modulatory effect of TLR2 ligands peptidoglycan (PGN) and tripalmitoyl-S-glycero-Cys-(Lys)4 (Pam3CSK4) on LL-37 induced LAD2 cells (a human mast cell line) activation. LL-37 induced LAD2 cells degranulation and the release of IL-8. TLR2 ligands didn't induce LAD2 cells degranulation, but triggered the release of IL-8. Incubation with PGN or Pam3CSK4 significantly suppressed LL-37-induced degranulation through inhibition of calcium mobilization from LAD2 cells. Similarly, the release of IL-8 was inhibited when LAD2 cells were co-stimulated with TLR2 ligands and LL-37. Studies with inhibitors of key enzymes involved in mast cell signaling indicated that the release of IL-8 induced by TLR2 ligands and LL-37 involved the activation of the PI3K, ERK, JNK and calcineurin signaling pathways. In contrast, p38 activation down-regulated the release of IL-8 induced by TLR2 ligands and LL-37. Taken together, these observations suggest that activation of human mast cells by LL-37 could be modified by TLR2 ligands and the function of human mast cells could be switched from allergic reactions to innate immune response. (C) 2016 Elsevier Inc. All rights reserved.National Natural Science Foundation of China [81271755, 81371737]; Guangdong Natural Science Foundation [2014A030313708]; Shenzhen Research Grant [CXZZ20140416144209739, JCYJ20130329110752142, KQCX20120803145850990]SCI(E)[email protected]; [email protected]
The phaeochromycins from streptomyces strain LL-P018: from taxonomy to novelties of biosynthesis
No full textThe phaeochromycins are a newly discovered family of aromatic polyketides produced by Streptomyces strain LL-P018. The novel phaeochromycins A and C are of medical interest as they have inhibitory activity against MK-2, a kinase involved in the inflammatory response. The phaeochromycins are structurally similar to actinomycete secondary shunt metabolites derived from the actinorhodin and enterocin biosynthetic pathways. Because these phaeochromycins show promise as potential anti-inflammatory therapeutic agents, further knowledge of their biosynthesis and the taxonomy of the producing organism was sought. Strain LL-P018 was identified taxonomically using a combination of traditional and molecular techniques. Analyses of morphology, physiology, 16S ribosomal RNA (16SrRNA) sequence, and ribosomal polymerase β- subunit (rpoB) gene sequence were used to identify LL-P018 as a strain of Streptomyces phaeochromogenes. New methods for strain comparison by combining genetic fingerprints and metabolite profiles in a single comparison were developed to assess strain variation between strain LL-P018 and closely related organisms. This approach also clarified relationships between multiple "types" and other published strains of S. phaeochromogenes and Streptomyces ederensis. Alnumycin, an additional aromatic polyketide which has structural similarities to the phaeochromycins, was produced by strain LL-P018 in liquid culture media. Genomic analysis of strain LL-P018 revealed the presence of a type II polyketide synthase gene cluster. Gene disruption experiments determined this pathway to be responsible for both phaeochromycin and alnumycin biosynthesis, suggesting that the phaeochromycins may be intermediates or shunt products in alnumycin biosynthesis.
This thesis describes a novel taxonomic approach to classification which integrates data from prior genetic and metabolic assessments into a single combined comparison. The S. phaeochromogenes type strain is defined, and taxonomic status of the species S. ederensis is clarified. New insights of phaeochromycin biosynthesis are revealed by cultural and genetic studies of Streptomyces strain LL-P018.Ph. D.Includes bibliographical references
LL-37-induced human mast cell activation through G protein-coupled receptor MrgX2
No full textHuman LL-37 is an important class of cationic antimicrobial peptide (CAP) that is known to stimulate mast cell activation. While many studies have been conducted on LL-37, to date little is known about the functional receptors for LL-37-induced human mast cell activation, in particular in terms of the release of de novo synthesized mediators. Thus, the aim of the present study is to identify the functional receptors for LL-37-induced human mast cell activation in terms of the degranulation and release of de novo synthesized mediators and investigate the downstream signalling pathways involved in mast cell activation. Overall, our study importantly demonstrates that LL-37-induced human mast cell degranulation and release of de novo synthesized mediators function primarily through the activation of MrgX2. We furthermore show that LL-37-induced human mast cell line LAD2 cells are involved in the degranulation and release of IL-8, and that FPRL1 and P2X7 have only a partial effect on IL-8 release, and no effect on mast cell degranulation triggered by LL-37. Instead, we find that silencing the expression of MrgX2 in human mast cell significantly inhibits the LL-37-induced degranulation and release of IL-8. Overall, this effect is associated with the activation of the Gi protein, PLC/PKC/Calcium/NFAT, PI3K/Akt and MAPKs signalling pathways.National Natural Science Foundation of China [81401299]; Natural Science Foundation of Guangdong Province [2014A030313711]; Characteristic innovation project of Guangdong Province Ordinary University [2015KTSCX120]; Shenzhen Peacock Plan [827-000209]SCI(E)ARTICLE6-124
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