Water soluble trehalose-derived oligoamides

A new family of oligotrehaluronamides was synthesized through the polycondensation of α,α-trehaluronic acid dimethyl ester and different diamines or polyamines. In particular, diamines with different molecular structure (1,n-alkylene diamines, aromatic diamine, and alkyleneoxydiamine) were used in order to modulate the molecular weights and the physical characteristics of the products, such as T_g, hydrophilic or hydrophobic properties, and solubility. α,α-Trehaluronic acid was obtained from a renewable source as α,α-trehalose. The syntheses of oligotrehaluronamides were carried out in different solvents such as ethanol, methanol, THF and DMSO, using triethylamine as catalyst. All the compounds obtained in this study were characterized through FT-IR and NMR spectroscopy. The molecular weights were evaluated by ¹H-NMR and in some cases compared with those obtained from ESI-MS spectrometry. Glass transition temperatures and melting points were detected by differential scanning calorimetry. Low molecular weight oligoamides, containing several hydroxyl groups, are water-soluble and could be used in water-based formulations.     

Immobilization of liposomes in nanostructured layer-by-layer films containing dendrimers

Artificial vesicles or liposomes composed of lipid bilayers have been widely exploited as building blocks for artificial membranes, in attempts to mimic membrane interaction with drugs and proteins and to investigate drug delivery processes. In this study we report on the immobilization of liposomes of 1,2-dipalmitoyl-sn-Glycero-3-[Phospho-rac-(1-glycerol)] (Sodium Salt) (DPPG) in layer-by-layer (LbL) films, alternated with poly(amidoamine) G4 (PAMAM) dendrimer layers. The average size of the liposomes in solution was 120 nm as determined by dynamic light scattering, with their spherical shape being inferred from scanning electron microscopy (SEM) in cast films. LbL films containing up to 20 PAMAM/DPPG bilayers were assembled onto glass and/or silicon wafer substrates. The growth of the multilayers was achieved by alternately immersing the substrates into the PAMAM and DPPG solutions for 5 and 10 min, respectively. The formation of PAMAM/DPPG liposome multilayers and its ability to interact with BSA were confirmed by Fourier transform infrared spectroscopy (FTIR). The structural features and film thickness were obtained using X-ray diffraction and surface plasmon resonance (SPR).     

A PNA-array platform for the detection of hidden allergens in foodstuffs

A duplex PCR method was developed to simultaneously detect the presence of hazelnut and peanut in raw materials and commercial products. It was found to be able to specifically detect traces of the investigated products down to 50 pg of their target DNA.A PNA array device has been designed and implemented to be used in combination with the duplex PCR in order to investigate the presence of traces of potentially allergenic nuts in foodstuffs. A PNA probe for each target amplified by the duplex PCR was designed, synthesized and characterized. The PNA probes were then deposited on commercial slides in order to build a PNA array to be used for recognizing the PCR products; the concentration of the probes as function of the concentration of the target DNA, together with the specificity of the probes were investigated.The conditions optimized during the setting of the experiment were used to obtain the final version of the PNA array which was then used to test several commercially available foodstuffs claiming to contain or not to contain the targeted nuts.     

Co-oligopeptides of glycine and aromatic amino acids with variable distance between the aromatic residues. IV. Spectroscopic properties of tryptophan-containing peptides in a cyclohexane phase

L-Tryptophan, L-tryptophanylglycine, glycyl-L-tryptophan, glycyl-L-tryptophanylglycine and glycyl-L-tryptophanylglycylglycyl-L-tryptophanylglycine have been transferred from an aqueous solution (generally 0.1 M NaOH) to cyclohexane, using the quaternary ammonium salt trioctylmethyl ammonium chloride (NR+4Cl-, soluble in cyclohexane but not in water) as the transporting agent. The spectroscopic properties of L-tryptophan and tryptophan-containing peptides have been studied in the cyclohexane phase. With respect to the aqueous solutions, ultraviolet absorption spectra are characterized by a considerable red shift of the absorption maxima and by a hypochromicity of up to 10%. Fluorescence spectra generally show emission maxima which are characteristic of polar environments, accompanied by a significant enhancement of the quantum yield. CD spectra have also been investigated for all peptides and compared with those for aqueous systems reported in preceding publications. All these spectral changes cannot be attributed solely to the cyclohexane solvent effect. It is suggested that these anomalous spectral properties of the tryptophan-containing compounds in the cyclohexane-NR+4 solution are due to the influence the electrostatic field of the ion pair has on the indole chromophore. The possible implications of this finding for the spectroscopic properties of aromatic residues buried in the polar interior of proteins are discussed.     

In vitro gastrointestinal digestion of the major peach allergen Pru p 3, a lipid transfer protein: Molecular characterization of the products and assessment of their IgE binding abilities

A simulated gastrointestinal digestion has been carried out on purified peach lipid transfer protein, one of the main allergens among the population of the Mediterranean area and the major allergen of peach allergic patients. The percentage of intact protein, after extensive digestion, measured by comparison with a non‐digestible peptide analogue used as internal standard, was found to be about one‐third of the original protein content. The peptides formed in digested fraction were characterized by means of LC/MS. The products of the digestion essentially derived from trypsin action, whereas the protein appeared to be resistant to pepsin and chymotrypsin. The identified peptides could be classified as low molecular weight and high molecular weight peptides. The latter consisted of the full protein, with the disulfide bridges still intact, deprived of the smaller peptides. The different digestion products, including the high and low molecular weight peptides, were purified by LC and assessed, together with the intact protein, by dot‐blot analysis with sera of allergic patients, allowing to estimate their potential allergenicity. The intact protein and the high molecular weight peptides were found to be recognized by patients' sera, whereas the small peptides were found to be not reactive.     

Strategy for a Scale‐up Correlation in a Dissolved Air Flotation Chamber

Beginning with a laboratory‐scale physical model, a scale‐up correlation for a pilot unit project was determined based on the analysis of dynamic similarity correlations involving the predominant phenomena of a dissolved air flotation (DAF) chamber. The implantation costs of pilot units require special strategies due to the lack of correlations of this type, as novel flotation methods have been considered strictly from an economic standpoint. With the aid of computational fluid dynamics and videos of microbubble and floc flow, inertia and gravity were identified as the predominant phenomena in a DAF chamber. The strategy described herein is simple and reduces the likelihood of future risks in scale‐up investments.     

The Autophagy-Related Organelle Autophagoproteasome Is Suppressed within Ischemic Penumbra

The peri-infarct region, which surrounds the irreversible ischemic stroke area is named ischemic penumbra. This term emphasizes the borderline conditions for neurons placed within such a critical region. Area penumbra separates the ischemic core, where frank cell loss occurs, from the surrounding healthy brain tissue. Within such a brain region, nervous matter, and mostly neurons are impaired concerning metabolic conditions. The classic biochemical marker, which reliably marks area penumbra is the over-expression of the heat shock protein 70 (HSP70). However, other proteins related to cell clearing pathways are modified within area penumbra. Among these, autophagy proteins like LC3 increase in a way, which recapitulates Hsp70. In contrast, components, such as P20S, markedly decrease. Despite apparent discrepancies, the present study indicates remarkable overlapping between LC3 and P20S redistribution within area penumbra. In fact, the amount of both proteins is markedly reduced within vacuoles. Specifically, a massive loss of LC3 + P20S immuno-positive vacuoles (autophagoproteasomes) is reported here. This represents the most relevant sub-cellular alteration here described in cell clearing pathways within area penumbra. The functional significance of these findings remains to be determined and it will take a novel experimental stream to decipher the fine-tuning of such a phenomenon.     

Study of the effect of the monomer pressure on the copolymerization of ethylene with 1-hexene

The effect of ethylene pressure on the copolymerization of ethylene with 1-hexene was studied. The results show an increasing of productivities (g of polymer/n_Zr h) with pressure. This tendency was not observed for the activity (g of polymer/n_Zr h bar) that decreases when pressure is raised. When varing the pressure, the characteristics and properties of the formed copolymers are in accordance with the expectation for changes in the monomer concentration; increasing the pressure causes a decrease in comonomer incorporation. At higher ethylene pressure, the polymer is more crystalline due to less incorporation of 1-hexene and the molecular weight is higher. The density of the copolymers also decreases with comonomer incorporation into the copolymer © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 2567–2574, 1997     

Volume computed tomography air kerma index and image quality evaluation in Brazil

The aim of this study was to evaluate the image quality of 29 computed tomography (CT) scanners in Brazil and to perform estimations of patient dose and image quality of common CT examinations at these equipment. The volume CT air kerma indexes (C(VOL)) were estimated, using normalised weighted air kerma indexes, supplied by the ImPACT group. The image quality tests were performed using the phantom and accreditation protocol from the American College of Radiology (ACR). The C(VOL) values for head scans varied between 8.7 and 108 mGy. The Hi-res chest examinations presented C(VOL) values varying from 0.4 to 32 mGy. For abdominal scans, the estimated C(VOL) values varied between 4.1 and 94 mGy. This wide variation of air kerma between different centres is related to the scanner type and also to the scanning parameters. The results also showed that the image quality did not attend all ACR CT accreditation requirements.