Sostenibilita' ambientale di tecnologie anti-fouling: studio dell'ecotossicita' di polimeri fouling-release

Con il termine biofouling si intende il fenomeno di accumulo e deposito di organismi viventi, animali e vegetali, unicellulari o pluricellulari su superfici naturali o artificiali immerse; tale aspetto costituisce un problema che deve essere contrastato e controllato quando si presenta l’esigenza di avere superfici efficienti dal punto di vista idrodinamico (es. carene di imbarcazioni, tubazioni). Il biofouling può essere schematicamente rappresentato come una successione ecologica in cui il microfouling (o biofilm), costituito da batteri, alghe unicellulari e cianobatteri, si instaura sulle superfici preparando le stesse all’attacco del macrofouling, costituito dall’insediamento di organismi marini di maggiori dimensioni sia di origine vegetale (macroalghe) che animale (serpulidi, cirripedi, bivalvi, spugne ed altro). Per contrastare l’attacco di organismi con spiccate capacità adesive possono essere usati prodotti vernicianti antivegetativi (antifouling) che contengono al loro interno molecole con azione biocida che vengono rilasciate con tempi e a concentrazioni differenti a seconda delle matrici in cui sono incorporate. Alcune sostanze ad azione biocida ed elevata efficacia impiegate nel corso degli anni hanno mostrato livelli di tossicità elevata nei vari comparti dell’ambiente marino (sedimenti, colonna d’acqua, organismi). Un esempio è dato dai composti organostannici (es. TBT), il cui uso come antivegetativi è stato vietato a seguito delle indicazioni dell’IMO e della convenzione internazionale (AFS) adottate il 5 ottobre 2002 dagli Stati membri dell’Unione Europea. Recentemente anche le vernici a base di composti rameici, ad oggi le più utilizzate, sono state vietate in Svezia. Una alternativa alle vernici contenenti biocidi potrebbe essere l’impiego di polimeri ad azione fouling-release, la cui azione non impedisce la formazione di biofouling ma ne facilita il distacco, a causa delle deboli interazioni che si creano tra la matrice e le strutture di adesione degli organismi. Lo scopo di questa tesi di laurea è quello di valutare l’ecotossicità di polimeri fouling-release per mezzo di saggi biologici su organismi modello quali batteri bioluminescenti (Vibrio fischeri), alghe unicellulari (Dunaliella tertiolecta) e crostacei (Artemia salina). I polimeri oggetto dello studio, sintetizzati dal gruppo del Prof. Giancarlo Galli (UNIPI), sono basati su una matrice di polidimetilsilossano (PDMS) a cui sono legati i differenti copolimeri con diverse caratteristiche di idrofilicità. I polimeri, depositati su vetro, sono stati lisciviati per 15 giorni in acqua di mare naturale seguendo il protocollo descritto da Karlsson & Eklund (2004). Sui lisciviati sono state condotte le prove di tossicità

Competing coexisting phases in 2D water

International audienceThe properties of bulk water come from a delicate balance of interactions on length scales encompassing several orders of magnitudes: i) the Hydrogen Bond (HBond) at the molecular scale and ii) the extension of this HBond network up to the macroscopic level. Here, we address the physics of water when the three dimensional extension of the HBond network is frustrated, so that the water molecules are forced to organize in only two dimensions. We account for the large scale fluctuating HBond network by an analytical mean-field percolation model. This approach provides a coherent interpretation of the different events experimentally (calorimetry, neutron, NMR, near and far infra-red spectroscopies) detected in interfacial water at 160, 220 and 250 K. Starting from an amorphous state of water at low temperature, these transitions are respectively interpreted as the onset of creation of transient low density patches of 4-HBonded molecules at 160 K, the percolation of these domains at 220 K and finally the total invasion of the surface by them at 250 K. The source of this surprising behaviour in 2D is the frustration of the natural bulk tetrahedral local geometry and the underlying very significant increase in entropy of the interfacial water molecules

Liquid Polymorphism and Double Criticality in a Lattice Gas Model

We analyze the possible phase diagrams of a simple model for an associating liquid proposed previously. Our two-dimensional lattice model combines oreintati onal ice-like interactions and \"{}Van der Waals\"{} interactions which may be repulsive, and in this case represent a penalty for distortion of hydrogen bonds in the presence of extra molecules. These interactions can be interpreted in terms of two competing distances, but not necessarily soft-core. We present mean -field calculations and an exhaustive simulation study for different parameters which represent relative strength of the bonding interaction to the energy penalty for its distortion. As this ratio decreases, a smooth disappearance of the doubl e criticality occurs. Possible connections to liquid-liquid transitions of molecul ar liquids are suggested

Hepatitis C Virus Infection and Human Pancreatic β-Cell Dysfunction

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Identification of MicroRNA-21 as a Biomarker for Chemoresistance and Clinical Outcome Following Adjuvant Therapy in Resectable Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) has a dismal prognosis. The high risk of recurrence following surgical resection provides the rationale for adjuvant therapy. However, only a subset of patients benefit from adjuvant therapy. Identification of molecular markers to predict treatment outcome is therefore warranted. The aim of the present study was to evaluate whether expression of novel candidate biomarkers, including microRNAs, can predict clinical outcome in PDAC patients treated with adjuvant therapy.Formalin-fixed paraffin embedded specimens from a cohort of 82 resected Korean PDAC cases were analyzed for protein expression by immunohistochemistry and for microRNA expression using quantitative Real-Time PCR. Cox proportional hazards model analysis in the subgroup of patients treated with adjuvant therapy (N = 52) showed that lower than median miR-21 expression was associated with a significantly lower hazard ratio (HR) for death (HR = 0.316; 95%CI = 0.166–0.600; P = 0.0004) and recurrence (HR = 0.521; 95%CI = 0.280–0.967; P = 0.04). MiR-21 expression status emerged as the single most predictive biomarker for treatment outcome among all 27 biological and 9 clinicopathological factors evaluated. No significant association was detected in patients not treated with adjuvant therapy. In an independent validation cohort of 45 frozen PDAC tissues from Italian cases, all treated with adjuvant therapy, lower than median miR-21 expression was confirmed to be correlated with longer overall as well as disease-free survival. Furthermore, transfection with anti-miR-21 enhanced the chemosensitivity of PDAC cells.. These data provide evidence that miR-21 may allow stratification for adjuvant therapy, and represents a new potential target for therapy in PDAC

An ecotoxicological study on tin- and bismuth-catalysed PDMS based coatings containing a surface-active polymer

Novel films were prepared by condensation curing reaction of a poly(dimethyl siloxane) (PDMS) matrix with bismuth neodecanoate and dibutyltin diacetate catalysts. An ecotoxicological study was performed on the leachates of the coatings using the bacterium Vibrio fischeri, the unicellular alga Dunaliella tertiolecta, the crustacean Artemia salina and the fish Sparus aurata (larvae) as testing organisms. A copper-based self-polishing commercial paint was also tested as reference. The results showed that the tin-catalysed coatings and the copper paint were highly toxic against at least two of the four test organisms, whereas bismuth-catalysed coatings did not show any toxic effect. Moreover, the same biological assessment was also carried out on PDMS coatings containing a surface-active fluorinated polymer. The toxicity of the entire polymeric system resulted only from the tin catalyst used for the condensation curing reaction, as the bismuth catalysed coatings incorporating the surface-active polymer remained atoxic toward all the tested organisms

Transcription analysis of human equilibrative nucleoside transporter-1 predicts survival in pancreas cancer patients treated with gemcitabine

Gene expression analysis may help the management of cancer patients, allowing the selection of subjects responding to treatment. The aim of this study was the characterization of expression pattern of genes involved in gemcitabine activity in pancreas tumor specimens and its correlation with treatment outcome. The role of drug transport and metabolism on gemcitabine cytotoxicity was examined with specific inhibitors, whereas transcription analysis of human equilibrative nucleoside transporter-1 (hENT1), deoxycytidine kinase (dCK), 5-nucleotidase (5′-NT), cytidine deaminase (CDA), and ribonucleotide reductase subunits M1 and M2 (RRM1 and RRM2) was done by quantitative reverse transcription-PCR in tumor tissue isolated by laser microdissection from surgical or biopsy samples of 102 patients. Association between clinical outcome and gene expression levels was estimated using Kaplan-Meier method and Cox's proportional hazards model. Transport and metabolism had a key role on gemcitabine sensitivity in vitro; moreover, hENT1, dCK, 5′-NT, CDA, RRM1, and RRM2 were detectable in most tumor specimens. hENT1 expression was significantly correlated with clinical outcome. Patients with high levels of hENT1 had a significantly longer overall survival [median, 25.7; 95% confidence interval (95% CI), 17.6-33.7 months in the higher expression tertile versus median, 8.5; 95% CI, 7.0-9.9 months in the lower expression tertile]. Similar results were obtained with disease-free survival and time to disease progression, and the multivariate analysis confirmed the prognostic significance of hENT1. This study suggests that the expression levels of hENT1 may allow the stratification of patients based on their likelihood of survival, thus offering a potential new tool for treatment optimization

Ampullary adenocarcinomas: The immunohistochemical score of CDX2, CK7 and CK 20 identify pathological subtypes and their prognosis

Background: Ampullary Adenocarcinomas (AACs) are an heterogeneous group of tumors and there are different methods of categorization of histological subtypes. Histology phenotype based on immunohistochemistry (IHC) of caudal-type homeodomain transcription factor 2 (CDX2) and Cytokeratins (CK7 and CK20) staining has been tested in order to identify three most important sub-classes: Intestinal (INT), Pancreato-Biliary (PB) and Mixed-Type (MT). The identification of MT tumor is often difficult with conventional histology and its clinical outcome is unclear. This study aims to identify only two subtype in AACs samples, using an IHC score based-on CDX2, CK7 and CK20 evaluation. Method: We arranged on TMA platform tissue samples from 20 patients with resected AAC and obtained their classification by histology and IHC expression of CDX2, CK7 and CK 20. We obtain IHC score for each marker summing the number of positive cells (0=no stained cells; 1< 25%; 2<50% and 3>50% and their intensity (1=weak; 2=middle and 3=strong). A global score (GS) for each tumor was obtained by the contribution of each marker. The MT tumor were located into INT or PB group on the basis of predominant immune-molecular phenotype. The overall survival values of INT and PB patients were obtained by Kaplan-Meyer methods. Results: Histological parameters defined AAC subtype samples as follows: 15% INT, 45%PB and 40% MT. Using the IHC expression and the GS,75% and 25% of MT samples were assigned to INT and PB, respectively. The mean value of GS was 9.5 (range 4-16). All INT samples had a GS over the mean, while all PB sample had a global score under the mean (p=0.0011). In particular, the INT samples are identified by high expression of CDX2 and CK20, while PB samples showed high expression of CK7 and negative expression of CK20 (p=0.0008). The Overall Survival (OS) of molecular intestinal histomolecular phenotype (INT) vs PB phenotype showed significant differences (85.7 vs 20.3 months, HR, 8.39; 95% CI, 1.38 to 18.90; p=0.0152). Conclusion: Histopathologic and molecular criteria combination define clinically relevant histomolecular phenotypes of AACs which could potentially represent distinct diseases with significant implications for current therapeutic strategies