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Block polyelectrolyte micelles/protein mixed nanostructures in aqueous media
Get PDFThe interactions between a globular protein, hen egg white lysozyme (HEWL), and star-like block polyelectrolyte micelles formed by the self-assembly of a poly(tertbutylstyrene)-b-poly(sodium(sulfamate-carboxylate)isoprene) (PtBS-SCPI) amphiphilic diblock copolymer were studied in aqueous solutions. Due to the opposite charges present in HEWL (positive charges) and on the SCPI polyelectrolyte coronas of the block copolymer micelles (negative charges), nanostructured hierarchical complexes are formed at neutral pH and low ionic strength. Structure and properties of the complexes were investigated by means of dynamic, static and electrophoretic light scattering, as well as atomic force microscopy. The solution behaviour, structure and effective charge of the formed nanoscale complexes proved to be dependent on the ratio of the two components. Presumably block polyelectrolyte micelles with a PtBS core and a SCPI corona decorated with HEWL molecules are initially formed. Moreover, the degree of charge neutralization caused by complexation determines the conformation and solubility of the complexes. Complexation of the macromolecular components at higher solution ionic strengths led to complexes of lower mass and nearly constant size. Such behavior may be correlated to the polyelectrolyte nature of the components. The structural investigation of the complexed protein by fluorescence and infrared spectroscopy revealed no signs of HEWL denaturation upon complexation
Δελτίο Τύπου [της Ημερίδας "Αξιολόγηση στην Εκπαίδευση: μύθος που μπορεί να γίνει πραγματικότητα;"]
No full textAbility of Salmonella enterica and Staphylococcus aureus to develop biofilm community on stainless steel and colonize rocket tissue
Get PDFSalmonella enterica and Staphylococcus aureus are important human pathogens capable of causing a diverse array of diseases, while international organization (EFSA, FAO/WHO) report that these are among the most related microorganisms for foodborne diseases. The ability of both species to form biofilm, together with the increased number of antibiotic-resistant S. aureus strains, including ones resistant to methicillin (MRSA), are of special interest for researchers. In addition, the consumption of raw plant tissues, have been recently associated with foodborne diseases outbreaks due to cross contamination. Obviously, the ability of pathogenic strains of these species to survive on either abiotic or plant surfaces needs to be further studied
Καθορισμός των βέλτιστων συνθηκών για την αποθήκευση των τροφών στις οποίες έχουν ενσωματωθεί τα φλαβονοειδή
Get PDFΗ ιδέα για την παραγωγή των λειτουργικών τροφίμων(fuctional foods) κερδίζει συνεχώς έδαφος στις μέρες μας, αφού το καταναλωτικό κοινό απαιτεί ολοένα και περισσότερο ποιοτικά και υγιεινά ζωικά προϊόντα. Συγκεκριμένες επεμβάσεις, όπως ο εμπλουτισμός του σιτηρεσίου των ζώων με αντιοξειδωτικές ουσίες (π.χ. βιταμίνες, συστατικά αιθερίων ελαίων), κινούνται προς αυτήν την κατεύθυνση και εφαρμόζονται με αυξανόμενο ρυθμό στη ζωική παραγωγή με σκοπό τη βελτίωση της ποιότητας των ζωοτροφών αλλά και της υγιεινής κατάστασης των παραγόμενων ζωικών προϊόντων (Bellisle et al., 1998). Ουσίες, που χρησιμοποιούνται ως πρόσθετα στις ζωοτροφές και έχουν αντιοξειδωτικό ρόλο, εμποδίζουν το σχηματισμό των ελεύθερων ριζών ή αντιδρούν με αυτές, σχηματίζοντας σταθερές ενώσεις, οι οποίες δε μεταβάλλουν σημαντικά τα θρεπτικά συστατικά και τα οργανοληπτικά χαρακτηριστικά τους. Χαρακτηριστικό παράδειγμα αποτελούν τα φλαβονοειδή, που περιέχονται στην πούλπα, τη φλούδα και την άσπρη ψίχα των εσπεριδοειδών, και έχουν έντονη αντιοξειδωτική και αντιφλεγμονώδη δράση, παρόμοια αυτής της βιταμίνης C. Δύο από τις κυριότερες ουσίες αυτής της κατηγορίας είναι η εσπεριδίνη και η ναρινγίνη, οι οποίες έχουν κινητοποιήσει το ενδιαφέρον των επιστημόνων, λόγω των ιδιαίτερων αντιοξειδωτικών και αντικαρκινικών ιδιοτήτων τους (Cano et al., 2008) και αποτελούν αντικείμενο μελέτης της συγκεκριμένης δράσης του «Θαλή»
Designer Xanthone An Inhibitor Scaffold for MDR-Involved Human Glutathione Transferase Isoenzyme A1-1
Get PDFGlutathione transferases (GSTs) are cell detoxifiers involved in multiple drug resistance (MDR), hampering the effectiveness of certain anticancer drugs. To our knowledge, this is the first report on well-defined synthetic xanthones as GST inhibitors. Screening 18 xanthones revealed three derivatives bearing a bromomethyl and a methyl group (7) or two bromomethyl groups (8) or an aldehyde group (17), with high inhibition potency (>85%), manifested by low IC50 values (7: 1.59 ± 0.25 μM, 8: 5.30 ± 0.30 μM, and 17: 8.56 ± 0.14 μM) and a competitive modality of inhibition versus CDNB (Ki(7) = 0.76 ± 0.18 and Ki(17) = 1.69 ± 0.08 μM). Of them, derivative 17 readily inhibited hGSTA1-1 in colon cancer cell lysate (IC50 = 10.54 ± 2.41 μM). Furthermore, all three derivatives were cytotoxic to Caco-2 intact cells, with 17 being the least cytotoxic (LC50 = 151.3 ± 16.3 μM). The xanthone scaffold may be regarded as a pharmacophore for hGSTA1-1 and the three derivatives, especially 17, as potent precursors for the synthesis of new inhibitors and conjugate prodrugs for human GSTs
Επιδράσεις των νεονικοτινοειδών και των αμιδίων του τετρονικού οξέος στο μεμβρανικό δυναμικό και στη συγκέντρωση του ενδοκυτταρικού ασβεστίου κυτταρικής σειράς νευροβλαστώματος N2a.
Get PDFDevelopment and validation of a semi-quantitative food frequency questionnaire for young school-aged children
Get PDFThe objective of the present study was to examine the validity for estimating energy and macronutrients intake of a newly developed picture aid, semi quantitative FFQ for Greek children and preadolescents. The two methods were found to agree in terms of mean energy intake according to the Bland and Altman method, although a trend in overestimating energy intake was found as the intake increased. Additionally, results of the Wilcoxon signed rank test revealed the similarity of the distribution in energy intake as estimated from the FFQ and the 3DD [median (IQR): 2038 (1264 - 2651) kcals for the FFQ vs. 1902 (1583 - 2324) kcals for the 3DD, p=0.33] (Table 1). Concerning macronutrients intake, according to the Bland and Altman method, although the mean difference was different than zero (all p’s <0.05), the agreement was considered adequate as the mean difference for each nutrient (with the exception of poly-unsaturated fatty acids) was < 1SD of the same nutrient intake as estimated from the reference method
The effect of controlled atmospheres on the composition and quality of dill (Anethum graveolens L. cv. Ducat) cultivated in spring and stored at two temperatures [Παρουσίαση]
Get PDFThis study was performed to evaluate four atmospheres varying in CO2 and N2 concentrations on the composition and quality of dill (Anethum graveolens L. cv. Ducat) during storage. Seeds were sown directly in the soil on 16/01/2010 and the plants harvested 93 days after sowing. The leaves (lamina and petiole) were weighed
at harvest and immediately transferred to airtight plastic bags within which the atmospheres were modified by injection of O2, CO2 and N2. The treatments that were applied (O2-CO2-N2) were: (1): 20-0-80, (2): 20-5-75, (3): 20-10-70, (4): 20-15-65. All samples were stored for 14 days at 2 or 5°C and the gas composition within the bags maintained at the desired levels. From the results, it was found that weight loss during storage varied between 7 and 12% at 2oC and 13 and 17% at 5oC irrespective of the gas composition. Vitamin C concentration decreased during storage, but at both storage temperatures the decrease was less at the highest CO2 level. The concentration of total phenolics decreased during storage, irrespective of the composition of the storage atmosphere. There was a loss of chlorophyll during storage, which tended to be greater at 5oC than at 2oC, but was prevented at both
temperatures by the highest CO2 concentration. In consequence, leaves stored under a gas composition of 20-15-65 (O2-CO2-N2) were greener at the end of storage. This, in conjunction with the relatively higher vitamin C concentration in this treatment,
indicates that 15% CO2 was the most suitable storage atmosphere for quality retention in dill, while the preferred temperature was 2oC due to lower weight loss