Search results for "Cero"
showing 10 items of 691 documents
Direct HPLC Monitoring of Lipase Activity in Reverse Micellar Media
1995
Given the profusion of biotechnological applications of the nonaqueous use of lipases, we have evaluated the possibilities of exploiting the inherent advantages of high performance liquid chromatography (HPLC) for a simple, rapid assay of lipase activity in reverse micellar media, as a convenient alternative to previously reported spectroscopic methods, using both a model system and esterification reaction, and different commercial lipases. The results obtained after a screening for optimized chromatographic conditions in the reverse-phase mode indicate that a satisfactory resolution of the reaction components can be obtained following a straightforward protocol, which permits an accurate, …
Expression patterns of complex glycoconjugates and endogenous lectins during fetal development of the viscerocranium
1999
Summary Experimental evidence suggests that carbohydrates and their corresponding receptors (endogenous lectins) decode biological information. Therefore, the expression of complex oligosaccharides — the potential ligand part of this recognition system — during chondrogenesis and osteogenesis was determined in the viscerocranium of fetal rats by mapping the staining patterns of exogenous lectins. Results were compared with the expression of bone- and/or cartilage-specific core proteins and the binding profiles of neoglycoconjugates. These synthetic tools make possible the localization of sugar-ligand-binding sites. The spatial and temporal distribution patterns of glycoconjugates were highl…
Mitogenic effects of phospholipase D and phosphatidic acid in transiently permeabilized astrocytes: effects of ethanol.
2003
Investigations of lipid-mediated signalling pathways are often limited by a lack of methods for the intracellular delivery of lipid messengers. We established a procedure for the transient permeabilization of astrocytes by an oxygen-insensitive mutant of streptolysin-O (SLO) to investigate the participation of the phospholipase D (PLD) signalling pathway in astroglial cell proliferation. Exogenous PLD, when incubated in the presence of SLO, caused an increase in DNA synthesis (measured by thymidine incorporation) which was completely suppressed by ethanol (0.3%, v/v). In parallel experiments, phosphatidic acid also induced a dose-dependent mitogenic response which, however, was not affected…
Cellule staminali di osteosarcoma umano 3AB-OS: un modello per analizzare le proprietà oncogeniche di p53 mutata.
2013
Alterazioni del gene TP53 si riscontrano in circa il 50% dei tumori umani (1). Negli ultimi anni è stato dimostrato che la proteina mutata p53 (mp53) acquisisce nuove proprietà oncogeniche, definite “gain of function” (GOF), che contribuiscono alla progressione tumorale (2). In questo studio è stato analizzato lo stato del gene TP53, della proteina da esso espressa e il loro ruolo nella promozione della proliferazione, invasività, resistenza all’apoptosi e staminalità delle cellule 3AB-OS, una linea tumorale staminale precedentemente isolata dalle cellule di osteosarcoma umano MG63 (3). Analisi comparative di RT-PCR, Methylation-Specific-PCR (MSP), Fluorescent-in situ-hybridization (FISH) e…
Further monotonicity and convexity properties of the zeros of cylinder functions
1992
AbstractLet cvk be the kth positive zero of the cylinder function Cv(x,α)=Jv(x) cos α−Yv sin α, 0⩽α<π, where Jv(x) and Yv(x) are the Bessel functions of the first and the second kind, respectively. We prove that the function v(d2cvkddv2+δ)cvk increases with v⩾0 for suitable values of δ and k−απ⩾ 0.7070… . From this result under the same conditions we deduce, among other things, that cvk+12δv2 is convex as a function of v⩾0. Moreover, we show some monotonicity properties of the function c2vkv. Our results improve known results.
Evidence for a surface self-cleaning sputtering mechanism in fast atom bombardment mass spectrometry
1985
Evidence for a surface self-cleaning sputtering mechanism in fast atom bombardment mass spectrometry involving significant sputtering from the bulk of the glycerol matrix has been obtained from (a) the time dependence of sample ion abundances and chemical noise for bioorganic compounds, (b) determinations of the sputtering volume in glycerol solution, and (c) studies of in situ chemical and biochemical reactions. The relevance of these results for optimal sample/matrix preparation in analytical applications is pointed out.
Role of calcium in the adhesion and fusion of bilayers.
1993
The interaction forces and fusion mechanisms of mixed zwitterionic-anionic phospholipid bilayers were measured with the surface forces apparatus. The bilayers were 3:1 mixtures of either dimyristoylphosphatidylcholine and dimyristoylphosphatidylglycerol (DMPC/DMPG) or dilauroylphosphatidylcholine and dilauroylphosphatidylglycerol (DLPC/DLPG), and experiments were carried out in NaCl solutions with and without CaCl2. In NaCl solutions, the forces between either mixed bilayer system were consistent with the DLVO (Derjaguin-Landau-Verwey-Overbeek) theory of repulsive electrostatic and attractive van der Waals forces, and fusion did not occur. At high pH (> 6) and in high (20 mM) NaCl concentra…
PRELIMINARY CHEMICAL CHARACTERIZATION OF TUNISIN MONOVARIETAL VIRGIN OLIVE OILS AND COMPARISON WITH SICILIAN ONES.
2007
Work was carried out on the characterization of monovarietal virgin olive oils (VOO) from Tunisia and Sicily (Italy). The two main Tunisian VOO (cvv. Chétoui of the North and cv. Chemlali grown in the Center and some regions of the South) and three principal Sicilian VOO (cvv. Nocellara del Belice, Biancolilla and Cerasuola) were studied. Moreover, the Chétoui oils were tested in a rain-fed control and an irrigation regime. All olive samples were picked at three different stages of ripeness. Analyses of major components (fatty acids and triacylglycerols) and minor ones (squalene, tocopherols and phenolic compounds) were carried out. Chétoui oils had a higher level of phenolic compounds foll…
Kinetics and equilibrium in insulin radioimmunoassay.
2002
The kinetics of insulin reaction has been studied with its specific antibody immobilized on the inner wall of the reaction tube; the radioimmunoanalytical determination of such a substance is based on the reaction. Independent variables were labelled and unlabelled insulin concentrations, temperature, viscosity, and the medium's ionic strength. Biexponential kinetics was found to be dependent on the concentrations fitted to the models discussed in the paper. The effect of temperature shows activation parameters similar to the viscous flow energy of water, which suggests that the reaction is diffusion-controlled. The results of the viscosity analysis points at the clearly negative influence …
Poly(glycolide) multi-arm star polymers: Improved solubility via limited arm length.
2010
Due to the low solubility of poly(glycolic acid) (PGA), its use is generally limited to the synthesis of random copolyesters with other hydroxy acids, such as lactic acid, or to applications that permit direct processing from the polymer melt. Insolubility is generally observed for PGA when the degree of polymerization exceeds 20. Here we present a strategy that allows the preparation of PGA-based multi-arm structures which significantly exceed the molecular weight of processable oligomeric linear PGA (<1000 g/mol). This was achieved by the use of a multifunctional hyperbranched polyglycerol (PG) macroinitiator and the tin(II)-2-ethylhexanoate catalyzed ring-opening polymerization of gly…