Valentina Gargiulo

Identification and structural determination of the capsular polysaccharides from two Acinetobacter baumannii clinical isolates, MG1 and SMAL

The structures of the capsular polysaccharides (CPSs) of the two clinical isolates Acinetobacter baumannii SMAL and MG1 were elucidated. Hot phenol/water extractions of the dry biomasses, followed by enzymatic digestions and repeated ultracentrifugations led to the isolation of polysaccharides that were negative in Western blot analysis utilizing an anti-lipid A antibody, thus proving that they were not the LPS O-antigens but CPSs. Their structures were established on the basis of NMR spectroscopy and GC-MS analyses. The A. baumannii MG1 CPS consisted of a linear aminopolysaccharide with acyl substitution heterogeneity at the N-4 amino group of QuipN4N: 4)-α-d-GlcpNAc-(1→4)-α-l-GalpNAcA-(1→3)-β-d-QuipNAc4NR-(1→ R=3-hydroxybutyrryl or acetyl. The repeating unit of the CPS produced by strain SMAL is a pentasaccharide, already reported for the O-antigen moiety from A. baumannii strain ATCC 17961:

Structural analysis of chondroitin sulfate from Scyliorhinus canicula: A useful source of this polysaccharide

Chondroitin sulfate (CS), a constituent of proteoglycans, is a key component of the connective tissues and it is widely used as a precautionary drug for joint diseases; for this reason, the increased demand of this polysaccharide has posed the problem to identify new and secure sources of this product. In this context, CS from the cartilage of the lesser spotted dogfish (Scyliorhinus canicula, a cartilaginous fish) was isolated and investigated through chemical and spectroscopical techniques. The structural elucidation was performed on the entire polysaccharide and confirmed analyzing the products obtained via ABC lyase treatment. As a result, its compositional analysis disclosed the occurrence of CS-A, CS-C, CS-D, and CS-0S motifs in the ratio of 41, 32, 19.8, and 8.2%, respectively. Additionally, two different glycopeptides were isolated and characterized via NMR, providing information on the linkage oligosaccharide region joining the glycosaminoglycan chain to the core protein. Therefore, chondroitin sulfate from Scyliorhinus canicula appears very similar to that isolated from shark, a cartilaginous and taxonomically related fish, with the main difference residing in the major percentage of the CS-A motif. In the light of the results obtained, Scyliorhinus canicula chondroitin sulfate possesses a chemical structure compatible for the formulation of commercial and pharmaceutical products.

Proinflammatory effects of diesel exhaust nanoparticles on scleroderma skin cells.

Autoimmune diseases are complex disorders of unknown etiology thought to result from interactions between genetic and environmental factors. We aimed to verify whether environmental pollution from diesel engine exhaust nanoparticulate (DEP) of actually operating vehicles could play a role in the development of a rare immune-mediated disease, systemic sclerosis (SSc), in which the pathogenetic role of environment has been highlighted. The effects of carbon-based nanoparticulate collected at the exhaust of newer (Euro 5) and older (Euro 4) diesel engines on SSc skin keratinocytes and fibroblasts were evaluated in vitro by assessing the mRNA expression of inflammatory cytokines (IL-1α, IL-6, IL-8, and TNF-α) and fibroblast chemical mediators (metalloproteases 2, 3, 7, 9, and 12; collagen types I and III; VEGF). DEP was shown to stimulate cytokine gene expression at a higher extent in SSc keratinocytes versus normal cells. Moreover, the mRNA gene expression of all MMPs, collagen types, and VEGF genes was significantly higher in untreated SSc fibroblasts versus controls. Euro 5 particle exposure increased the mRNA expression of MMP-2, -7, and -9 in SSc fibroblasts in a dose dependent manner and only at the highest concentration in normal cells. We suggest that environmental DEP could trigger the development of SSc acting on genetically hyperreactive cell systems.

Insights on the Conformational Properties of Hyaluronic Acid by using NMR Residual Dipolar Couplings and MD simulations

The conformational features of hyaluronic acid, a key polysaccharide with important biological properties, have been determined through the combined used of nuclear magnetic resonance (NMR) spectroscopy and molecular modeling techniques. A decasaccharide fragment of sodium hyaluronate (HA) was submitted to 3.5 ns of molecular dynamics in explicit water environment form. The same decasaccharide was prepared by hyaluronidase digestion for the experimental study. The approach consisted in the measurements of NMR residual dipolar coupling (RDC) which were used to filter the molecular dynamics data by retaining those structures which were in agreement with the experimental observations. Further analysis of the new conformer ensemble (HA(RDC)) and clustering the molecules with respect to their overall length led to seven representative structures, which were described in terms of their secondary motifs, namely the best fitting helix geometry. As a result, this protocol permitted the assessment that hyaluronic acid can adopt two different arrangements, which can be described by a three- or four-folded left-handed helix, with a higher occurrence of the first one.

Supplementing π-systems: eumelanin and graphene-like integration towards highly conductive materials for the mammalian cell culture bio-interface

Organic (bio)electronics appears to be the first target for competitive exploitation in the materials science of eumelanins, black insoluble photoprotective human biopolymers. Nonetheless, the low conductivity of these pigments is limiting the implementation of eumelanin-based devices. Here we present a novel organic/organic hybrid material (EUGL) by integration of conductive graphene-like (GL) layers within the EUmelanin pigment (EU). GL layers were obtained by a two-step oxidation/reduction of carbon black. The stability of GL layers over a wide pH range and the self-assembling tendency place this material in a leading position for the fabrication of hybrid materials in aqueous media. EUGL was obtained by inducing the polymerization of eumelanin precursors (5,6-dihydroxyindole, DHI and 5,6-dihydroxyindole-2 carboxylic acid, DHICA) in aqueous media containing GL layers. The new material featured promising biocompatibility and an increased conductivity with respect to eumelanin by four orders of magnitude.

Characterization of Soot

The characterization of physical and chemical properties of the carbon particulate matter commonly named soot is relevant in the research on pollutants emitted in the atmosphere from combustion and industrial plants. The selection and the standardization of advanced analytical methods are necessary to provide reliable and reproducible results on the characteristics of carbon material. This chapter reports an overview of the main off-line techniques available to characterize carbon materials as: elemental analysis, physical adsorption with the determination of the specific surface area, electronic microscopy techniques, X-ray diffraction, Raman spectroscopy, thermogravimetric analysis, infrared spectroscopy, soot reactivity toward O2 and NO, UV–Visible spectroscopy, size exclusion chromatography and fluorescence spectroscopy. The results of the implementation of these techniques on a commercial standard carbon material (Printex-U carbon black), considered as analog of soot, are reported as case study.

Structural elucidation of the capsular polysaccharide isolated from Kaistella flava

The Gram-negative bacterium under study belongs to the genus Kaistella. It was isolated from a soil sample of the Haian Island in China, and it produces a lipophilic polysaccharide characterised by a branched hexasaccharide repeating unit, counting four 6-deoxy-alpha-l-mannose (Rha) residues, one 2-acetamido-2-deoxy-beta-d-glucose (GlcNAc) and a 2-acetamido-2,6-dideoxy-beta-d-galactose (FucNAc) unit. The structure of the repeating unit, assigned through 2D-NMR spectroscopy, is herein reported for the first time: [carbohydrate structure: see text]

The structure of the carbohydrate backbone of the lipooligosaccharide from an alkaliphilic Halomonas sp.

The structure of the carbohydrate backbone of the core-lipid A region of the lipooligosaccharide (LOS) of the alkaliphilic and slightly halophilic bacterium Halomonas sp. has been elucidated. The LOS was fully deacylated, dephosphorylated, and reduced at the free reducing end. The structure, obtained by means of compositional analysis, 2D NMR spectroscopy, and MALDI mass spectrometry, was determined as the following: [ structure: see text ]. All sugars are d-pyranoses; Hep is l-glycero-d-manno-heptose and Kdo is 3-deoxy-d-manno-oct-2-ulosonic acid.

THz spectroscopy on graphene-like materials for bio-compatible devices

Graphene-like (GL) layers and eumelanin-based graphene-like (EUGL) hybrids have been investigated through THz time domain spectroscopy. The interest in these materials lies on their peculiar chemical-physical properties: the former are conductive water stable materials, whereas the latter are biocompatible materials with good conductive and adhesive properties. Both exhibit promising optoelectronic and bioelectronic applications. We measured mixtures of GL layers or EUGL hybrids with KBr, shaped in pellets with uniform thickness, in order to circumvent problems related to sample inhomogeneity and roughness. A mean field theory was applied to extract direct information on permittivity and conductivity. Data have been carefully fitted through the Drude-Smith theory, confirming the conductive nature of the hybrid materials. The results show that EUGL hybrid-based devices can be promising for the next generation of printable bio-circuits.

Rhizobium rubiT : A Gram-Negative Phytopathogenic Bacterium Expressing the Lewis B Epitope on the Outer Core of its Lipooligosaccharide Fraction

The structure of the core oligosaccharide from the phytopathogenic bacterium Rhizobium rubi was deduced by combining information from complementary chemical approaches (alkaline and acid hydrolysis), similar to the “overlap peptide” strategy. This structure is new and it contains two main oligosaccharide backbones that differ in the substitution degree of the external Kdo unit. The relevant feature shared by both oligosaccharides is the presence of a tetrasaccharide motif that is similar to the blood group Lewis B antigen (LeB). This epitope differs from LeB in the glycosidic configuration of the glucosamine unit (α and not β) and in the occurrence of acetyls substituents at O3 and/or O4 of the galactose moiety. Other notable structural features are the location of the Dha residue, the presence of a α‐glucose unit that is linked to the inner Kdo unit, the high number of acid sugars and the highly branched core structure.