4,212 research outputs found
Natalia 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
Evaluación de la actividad antibiopelícula de péptidos sintéticos análogos a catelicidina humana LL-37 en aislamientos clínicos de Staphylococcus spp. en Bogotá Colombia
No full textEn este trabajo, se diseñaron con ayuda de herramientas bioinformáticas cuatro secuencias análogas a la catelicidina humana LL-37, (LL37-1, LL37-2, LL37-3 y LL37-4) con el fin de probar su actividad anti-biopelícula en aislamientos clínicos de Staphylococcus spp, caracterizadas genotípica (identificación de los genes operón IcaRADBC) y fenotípicamente (formación de biopelícula y perfil de resistencia). Los péptidos fueron sintetizados usando la estrategia de Fmoc, se purificaron por RP-HPLC y se caracterizaron por espectrometría de masas MALDI-TOF MS. Los ensayos in vitro de la actividad antibiopelícula por cabina de flujo continuo celular muestran que una concentración de 5 µM fue suficiente para inhibir la formación de biopelícula de Staphylococcus spp; mientras que, en ensayos estáticos por cristal violeta se necesitó una concentración entre 25-50 µM. Además se evaluó el posible efecto deletreo de las secuencias peptídicas mediante la liberación de la enzima Lactato Deshidrogenasa (LDH) en células humanas y su actividad hemolítica. Según los resultados de citotoxicidad, a una concentración de 6,125 µM se presentó un nulo efecto hemolítico, incluso a concentraciones elevadas de (100 µM) y un bajo porcentaje de citotoxicidad (menor al 10%) en PBMCs. Por lo anterior, el uso de péptidos análogos de la catelicidina representa una alternativa promisoria para tratar infecciones asociadas a la biopelícula.Abstract. In this work, four sequences analogous to human cathelicidin LL-37 (LL37-1, LL37- 2, LL37-3 and LL37-4) were designed with the help of bioinformatic tools in order to test their anti-biofilm activity in Clinical isolates of Staphylococcus spp, characterized genotypic (identification of genes operon IcaRADBC) and phenotypically (biofilm formation and resistance profile). Peptides were synthesized using the Fmoc strategy, purified by RP-HPLC and characterized by MALDI-TOF MS mass spectrometry. In vitro assays of the antibiotic activity by continuous cell flow showed that a concentration of 5 μM was sufficient to inhibit the biofilm formation of Staphylococcus spp; while in static crystal violet tests a concentration between 25-50 μM was required. In addition, the possible spelling effect of the peptide sequences was evaluated by the release of the enzyme Lactate Dehydrogenase (LDH) in human cells and their hemolytic activity. According to the cytotoxicity results, at a concentration of 6,125 μM there was no hemolytic effect, even at high concentrations of (100 μM) and a low percentage of cytotoxicity (less than 10%) in PBMCs. Therefore, the use of analogous peptides of cathelicidine represents a promising alternative to treat infections associated with the biofilm.Maestrí
De la luz de Roma al oro de Florencia. Luz y legitimación histórica en los humanistas italianos
No full textDurante el Renacimiento, desde
sus inicios hasta su consolidación, los humanistas utilizaron la contraposición entre
luz y oscuridad para legitimar, frente a la
medieval, su nueva visión del mundo. En el
presente artículo analizaremos el significado concreto con que se dota a la luz en dicha contraposición, así como las diferentes
modulaciones que adquiere, dentro de lo
que hemos llamado la Edad de la luz.. In Renaissance, from its beginning
to its consolidation, humanists used the
light/darkness opposition to legitimate, in
front of the medieval one, their new world
vision. In this paper we�ll analyze the specific meaning with light is provided with
in that opposition, as well as the different
modulations that this light acquires, in what
we have named the Light�s Age
Recommended from our members
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
Transmisión de luz a traves de discos de cerámica de vidrio reforzada por disilicato de litio de diferente espesor y translucidez con dos sistemas led
No full textLa transmisión de luz (TL) a través de restauraciones cerámicas es influenciada por su translucidez, su grosor y la unidad de fotocurado; afectando éstos al grado de polimerización de los agentes de cementación resinosos. El propósito de la investigación fue comparar la TL a través de discos de cerámica de vidrio reforzada por disilicato de litio de diferente espesor y translucidez, expuestos con luz LED de dos marcas comerciales (L1 y L2). La potencia emitida por ambas lámparas fue medida con un radiómetro, de 1200 y 1100 mW/cm2 respectivamente. Estas unidades irradiaron los discos de 0.5 mm (d1), 1mm (d2) y 1.5 mm (d3) fabricados en sus alternativas de alta translucidez (HT), baja translucidez (LT), mediana opacidad (MO) y alta opacidad (HO) registrándose la intensidad de luz transmitida (mW/cm2). Los valores de TL obtenidos al exponer diferentes translucideces del mismos espesor con L 1 y L2 fueron comparados individualmente, e intergrupos. Valores promedio de (±SD) fueron: de Ll-d1: 520,460,390 y <300. De L2-d1 :400,340,370 y <300.De Ll-d2: 310, <300,<300, <300. Finalmente, las combinaciones L2-d2, Ll-d3 y L2-d3 emitieron valores menores a 300 mW/cm2 • Ambas lámparas emitieron suficiente energía de luz para polimerizar espesores de 0,5 mm que no sean HO. Se concluye que la intensidad de transmisión de luz es alterada por el grosor y tipo de cerámica, además de la unidad de fotocurado. Con lámparas de alta potencia pero reputación desconocida podría existir insuficiente transmisión de luz.Tesi
- …
