Malignant melanoma cancer is the sixth common cancer diagnosed in the United States. Surgery, chemotherapy and radiation are some of the successful techniques in killing tumor cells. However, in these techniques, it is not easy to distinguish tumor cells from the healthy once which inadvertently get exposed to chemical agent/radiation. Therefore it is required to develop an anticancer agent which selectively kills the cancer cells, while still protecting the normal tissues. In our preliminary work, we have shown that Dextran (1000Da) coated Cerium oxide nanoparticles (Dex-CNPs) selectively kills the cancer cells (50% killing at a concentration of 150μM) without inducing toxicity to the normal cells. However, the mechanism involved on how CNPs/Dex-CNPs attain the selectivity and efficiently kill the tumor cells is still unknown. In this study we have synthesized Dextran coated ceria nano particles (Dex- CNPs) with different surface oxidation state ratio (Ce4+/Ce3+). This will provide an in depth understanding of the key chemical and physical properties of the system that can improve its efficacy. The varied surface oxidation of the particles is achieved by exposing Dex-CNPs to light which initiates a color change from dark to pale yellow indicating the reduction of Ce4+ to Ce3+. Interestingly we have found that the DexCNPs exposed to light have reduced cytotoxicity towards squamous cell carcinoma cell line (CCL30) compared to the protected once. Characterization of the same revealed that Dex- CNPs exposed to light have decreased Ce4+ /Ce3+ surface oxidation ratio compared to the other. This provides more insight in useful synthesis of Dex-CNPs in terms of storage and handling. In summary, higher Ce4+ /Ce3+ surface oxidation ratio is more efficient in hindering tumor growth by effectively hindering the tumor-stoma interaction.

Platelets play a vital role in processes of hemostasis and thrombosis under physiological and pathological conditions. Following vascular damage, platelets will accumulate and stably adhere to exposed subendothelial matrixes. The binding of platelet surface receptor Glycoprotein VI (GPVI) to exposed collagen initiates a signaling cascade, which culminates in platelet activation. Stimulation of GPVI pathways results in the generation of thromboxane and causes the platelets to secrete their granule contents. This generated thromboxane as well as constituents released from dense granules such as ADP, and serotonin, play an essential role in potentiating the platelet response through activation of other surface receptor mediated pathways. Importantly, downstream of all these separate pathways, kinases become activated and play a crucial role in phosphorylating their substrates to elicit critical cellular responses. Previously published studies have established the importance for myosin kinase in its role for phosphorylating the myosin light chain (MLC) downstream of ADP receptors. These studies have shown MLC phosphorylation occurs rapidly and is essential for shape change following the stimulation of ADP receptors. Technological advances in antibody development have resulted in the generation of commercially available phospho-specific antibodies for MLC phosphorylated on either threonine (Thr) 18 or serine (Ser) 19. These antibodies allowed us to revisit these prior studies and address whether phosphorylation on MLC (Ser) 19 would elicit one response while phosphorylation on (Thr) 18 may result in another functional response. Our result show, that MLC is phosphorylated rapidly on (Ser) 19 and plays an important role in shape change downstream of Gq pathways, while MLC (Thr) 18 phosphorylation occurs at a slower rate downstream of G12/13 pathways and contributes to platelet dense granule secretion. Protein kinase C's (PKC) are serine/threonine kinase, which become activated following the stimulation of many of the platelet surface receptors. PKCs are classified into three groups, classical (α, βI, βII, γ), novel (δ, ε, η, θ), and atypical (ζ, ι, λ, μ) based on their cofactor requirements for activation. The classical PKCs, which require diacylglycerol and calcium for their activation were investigated using the specific inhibitor Go6976. Much to our surprise, we demonstrated that downstream of GPVI pathways, Go6976 caused non-selective inhibition of Spleen tyrosine kinase (Syk) activity. This inhibition of Syk activity resulted in a concentration-dependent reduction in phosphorylation of downstream molecules Lat and PLCγ2 as well as platelet aggregation and secretion. Stimulation of surface receptors GPVI, CLEC-2, GPIb, and FcRIIa, all lead to the activation of tyrosine kinase pathways. The role for Syk in these pathways is essential and in the absence of its activity these pathways are completely shut down. We inadvertently discovered dextran sulfate (DxS) actives platelets. Our results show that DxS activates a Src-dependent pathway which does not utilize surface receptors GPVI, CLEC-2, GPIb, or FcRIIa. Platelets pretreated with Syk inhibitors OXSI-2 or Go6976 failed to cause αIIbβ3 activation in response to convulxin, however, platelets activated with DxS under the same conditions retained the ability to activate αIIbβ3. In response to DxS, platelet aggregation, intracellular calcium mobilization, and αIIbβ3 activation were significantly inhibited in platelets pre-treated with PI-3K inhibitors. Taken together these results for the first time establish a novel tyrosine kinase pathway in platelets that cause fibrinogen receptor activation in a PI-3K dependent manner without a role for Syk. In conclusion, we have evaluated the role of myosin light chain kinase, Syk, and PI-3 kinase downstream of platelet receptor-mediated pathways. We have examined the phosphorylation status of several of their effector molecules and have correlated these events with their functional responses in platelets. Here we have highlighted several roles for platelet kinases and their relative importance in regulating platelet functional outcomes. / Physiology

Polysaccharides are known as among the most abundant natural polymers on the Earth. As this class of material is usually renewable, biodegradable, biocompatible in many contexts and environmentally friendly, it is of great interest to use these benign polymers to design and prepare materials, especially for applications with green and biomedical purposes. In this dissertation we will discuss novel pathways to two different types of polysaccharide-based materials: block copolymers and hydrogels. Block copolymers are composed of two or even more covalent bonded polymer blocks that have quite distinct properties. Synthesis of polysaccharide-based block copolymers is an attractive and challenging research topic, opening up promising application potential and requiring advances in polysaccharide regio- and chemoselectivity. Herein, we report two independent approaches to prepare these interesting and potential useful materials. In one approach, trimethyl cellulose was modified regiospecifically at the reducing end anomeric carbon to create an ω-unsaturated alkyl acetal by solvolysis with an ω-unsaturated alcohol. Then, olefin cross-metathesis, a known versatile and mild tool for polysaccharide chemical modification, was used to couple the trimethyl cellulose block with various polymer blocks containing acrylates. To demonstrate the method, trimethyl cellulose-b-poly(tetrahydrofuran), cellulose-b-poly(ethylene glycol), and cellulose-b-poly(lactic acid) were synthesized by this coupling strategy. In another approach, we introduced a simple and novel method to prepare dextran-based block copolymers. In this strategy, N-bromosuccinimide (NBS)/triphenyl phosphine (PPh3) was chosen to regioselectively brominate the only primary alcohol of linear unbranched dextran. The resulting dextran, bearing a terminal C-6 bromide, was coupled with several amine terminated polymers via SN2 substitution to obtain block copolymers, including dextran-b-polystyrene, dextran-b-poly(N-isopropylacrylamide) and dextran-b-poly(ethylene glycol). Dextran-b-poly(N-isopropylacrylamide) exhibits thermally-induced micellization as revealed by dynamic light scattering, forming micelles with 155 nm diameter at 40 °C. Dextran-b-polystyrene film was analyzed by small angle X-ray scattering, suggesting the existence of microphase separation. This dissertation also introduces a novel, simple and effective strategy to prepare polysaccharide-based hydrogels. Hydrogels are typically crosslinked hydrophilic polymers that have high water affinity and no longer dissolve in water. Polysaccharide-based hydrogels are of great interest to for biomedical applications due to their benefits including biocompatibility, polyfunctionality, and biodegradability. Recently the Edgar group has discovered that chemoselective oxidation of oligo(hydroxypropyl)-substituted polysaccharides impairs ketone groups at the termini of the oligo(hydroxypropyl) side chains. These ketones can condense with amines to form imines, leading hydrogel formation., Based on this concept, we prepared oxidized hydroxypropyl polysaccharide/chitosan hydrogels. This class of all-polysaccharide hydrogels exhibits a series of interesting properties such as tunable moduli (300 Pa to 13 kPa), self-healing, injectability, and high swelling ratios. To further explore imine-crosslinked hydrogels, we designed thermally responsive hydrogels by using a Jeffamine, a polyethylene oxide-b-polypropylene oxide-b-polyethylene oxide triblock copolymer with two terminal amines. As the Jeffamine has a lower critical solution temperature, oxidized hydroxypropyl cellulose/Jeffamine hydrogels display moduli that are tunable by controlling the temperature. / Doctor of Philosophy / Polysaccharide are natural polymers that are among the most abundant polymers on Earth. It is greatly in society's interest to extend the scope of their applications, due to the benign nature of polysaccharides. This dissertation mainly focuses on two polysaccharides: cellulose and dextran. Cellulose is a long linear polymer of linked glucose molecules. As cellulose is sustainable, biodegradable, non-toxic, affordable and accessable for chemical modification, it is a suitable polymer for biomedical and environmentally friendly application. Dextran is also a polymer chain made up only of glucose but connected with each other differently from cellulose by, bacterial fermentation, and it may be lightly branched. It is biocompatible in many situations and is biodegradable both in vivo and in the environment, thus it has been investigated for drug delivery and many other medical applications. Using these two polysaccharides, we designed and prepared two quite different classes of materials: block copolymers and hydrogels. Block copolymers consist of two or more different types of polymer blocks connected by strong covalent bonds. As block copolymerization enables construction of a single polymer comprising segments with distinct properties, it is appealing to synthesize a block copolymer which preserves the properties of natural polymers coupled to very different polymers, such as polyolefins (e.g. the polyethylene that is used for milk bottles). In order to prepare polysaccharide-based block copolymers, we developed two different synthetic routes to end-functionalize methyl cellulose and dextran , and these resulting products were used to prepare two independent series of polysaccharide-based block copolymers via combination (in other words, sticking the polysaccharide and, e.g., the polyethylene together end to end). This study confirms the feasibility of this method to make methyl cellulose-based and dextran-based block copolymers. We expect these classes of materials will have significant potential in applications including drug delivery, as compatibilizers for polymer blends of materials that otherwise cannot be mixed (polyolefin/polysaccharide), membrane and adhesive. Hydrogels are crosslinked polymer networks with high water affinity, and they have been heavily investigated in the field of tissue engineering, drug delivery, agriculture and 3D printing. Polysaccharide-based hydrogels are attractive materials for these applications because they are biocompatible, biodegradable and have polyfunctionality. However, any use of toxic small molecules to crosslink the hydrogels diminishes their usefulness in biomedical applications. In this work, we demonstrate a simple, green and efficient method for preparation of all-polysaccharide-based hydrogels. The starting materials, oxidized hydroxypropylpolysaccharide, were simply prepared by using household bleach (NaOCl) as the oxidation reagent. We discovered that oxidized hydroxypropyl polysaccharides readily form hydrogels with hydrophilic amine-containing polymers like chitosan (a natural polysaccharide that comes from shells of crustaceans like crabs or shrimp) and Jeffamines, affording interesting properties including tunable stiffness, self-healing, injectability, and responsiveness to acidity and temperature. We expect that this new class of hydrogel will be very promising for biomedical-related applications.

L’administration de fer dextran à 10 mg/kg intramusculaire (IM) est un traitement empirique couramment recommandé en médecine aviaire lors d’hémorragie ou d’anémie. L’objectif principal de cette étude était d’évaluer les effets de ce traitement sur l’anémie chez les oiseaux de proie. Deux types d’individus ont été utilisés : des crécerelles d’Amérique (Falco sparverius) où une anémie par perte de sang externe aiguë a été créée (deux phlébotomies de 20-40 % du volume sanguin total à un intervalle de 6 h) et des oiseaux de proie sauvages de différentes espèces souffrant d’anémies diverses. L’ensemble des oiseaux a été subdivisé aléatoirement en groupe traitement (fer dextran 10 mg/kg IM) et contrôle (NaCl 0,9% IM). Un suivi dans le temps a été réalisé afin d’étudier leur récupération de l’anémie, la présence d’effets secondaires au traitement et l’impact d’une administration de fer sur ces réserves. Aucune différence significative n’a été observée entre les deux groupes en ce qui concerne les signes cliniques, l’hématocrite, le pourcentage des polychromatophiles/réticulocytes, la densité cellulaire et le fer de la moelle osseuse, la créatine kinase et le fer plasmatique. La majorité des crécerelles ont présenté une myosite au site d’injection du fer. Nos résultats suggèrent qu’une administration de 10 mg/kg de fer dextran IM n’a pas d’effet sur l’érythropoïèse des rapaces souffrant d’anémie par perte de sang externe aiguë, qu’elle provoque une légère inflammation au site d’injection et qu’elle n’influence pas les réserves de fer. Le comptage des réticulocytes en anneau et des polychromatophiles semble être deux méthodes équivalentes. / A 10 mg/kg intramuscular (IM) administration of iron dextran is a common empirical treatment recommended in avian medicine for hemorrhage and anemia. The purpose of this study was to evaluate the effects of this treatment on anemia in birds of prey. Two kinds of specimen were used: the American kestrel (Falco sparverius) where an acute external blood loss anemia was created (with two phlebotomies of 20-40 % of the total blood volume at 6 hours interval) and other various species of wild birds of prey suffering from different types of anemia. All subjects were randomized into a treatment (iron dextran 10 mg/kg IM) or a control (NaCl 0,9 % IM) group. Monitoring was carried out to evaluate the evolution of the anemia, presence of side effects and impact of an iron administration on their iron reserve. No significant differences were observed between the two treatment groups for clinical signs, packed cell volume, the percentage of reticulocytes/polychromatophilic erythrocytes, bone marrow cellularity and iron, plasmatic iron and creatine kinase. Most kestrels had a myositis at the iron injection site. Our results suggest that an IM injection of 10 mg/kg iron dextran has no effect on raptor erythropoiesis after an acute external blood loss anemia, that it has no effect on iron reserve, and that it can cause mild inflammation at the injection site. The polychromatophilic erythrocytes and the reticulocytes ring form count were two equivalent methods.

Un dispositif expérimental a été développé pour l'étude du couplage de la croissance d'un biofilm de Shewanella oneidensis MR-1 et du transport conservatif de l'Erioglaucine. La croissance du biofilm a été suivie par mesure de conductivité hydraulique et par acquisition d'images à l'aide d'une caméra digitale. La fraction volumique du biofilm a été caractérisée par des essais d'élution d'une macromolécule (i.e. : le Bleu Dextran) par analogie avec les méthodes de chromatographie d'exclusion ou de filtration sur gel. Ainsi au bout de 29 jours, un biofilm quasi-homogène sur l'ensemble de la cellule d'écoulement (0,1×0,1×0,05m3) et équivalent à 50% du volume poral a été formé. L'influence de la croissance du biofilm sur les propriétés de transport du milieu a été évaluée. Les essais de transport conservatif de l'Erioglaucine effectués pour deux vitesses d'injection et à deux stades de croissance du biofilm (17 et 29 jours) ont montré l'influence d'hétérogénéités locales sur les paramètres de transport (i.e. : la porosité, la perméabilité et la dispersion hydrodynamique). Ainsi après 17 jours de culture quand le biofilm occupe partiellement le milieu poreux (moitié inférieure) un modèle à deux équations ou double milieu permet de caractériser le transport conservatif. A contrario après 29 jours de culture où le biofilm occupe tout le milieu poreux, un comportement fickien classique caractérise le transport. Les valeurs théoriques du coefficient de dispersion longitudinale prédites par la méthode de prise de moyenne volumique ont permis de reproduire de manière satisfaisante le comportement observé expérimentalement / An experimental device was performed for the study of coupling the growth of a Shewanella oneidensis MR-1 bacterial biofilm and the non reactive transport of Brilliant Blue FCF. The biofilm growth was monitored by hydraulic conductivity measurements and by image acquisition with a digital camera. The biofilm volume fraction was estimated through tracer experiments with a macromolecular tracer (i.e., Dextran Blue) as in size-exclusion chromatography or gel filtration chromatography. Then after 29 days of bacterial culture a quasi-homogenous biofilm was grown in the whole flow cell (0,1×0,1×0,05m3) occupying about 50% of void space volume. The influence of biofilm growth on porous media transport properties was evaluated. Conservative tracer experiments with Brilliant Blue FCF run at two hydrodynamic conditions and at two growth steps of biofilm (17 and 29 days) showed the influence of local heterogeneities on transport parameters (i.e., porosity, permeability and hydrodynamic dispersion). Then at 17 days of growth when the biofilm partially covers the porous medium (bottom half of the flow cell) a two-equation model or double-layer model was suitable to characterize the conservative transport. A contrario after 29 days of growth, when the biofilm covers the whole porous medium, a classical fickian model was convenient. Numerical values of longitudinal dispersion coefficient from volume averaging well fitted experimental results

L’administration de fer dextran à 10 mg/kg intramusculaire (IM) est un traitement empirique couramment recommandé en médecine aviaire lors d’hémorragie ou d’anémie. L’objectif principal de cette étude était d’évaluer les effets de ce traitement sur l’anémie chez les oiseaux de proie. Deux types d’individus ont été utilisés : des crécerelles d’Amérique (Falco sparverius) où une anémie par perte de sang externe aiguë a été créée (deux phlébotomies de 20-40 % du volume sanguin total à un intervalle de 6 h) et des oiseaux de proie sauvages de différentes espèces souffrant d’anémies diverses. L’ensemble des oiseaux a été subdivisé aléatoirement en groupe traitement (fer dextran 10 mg/kg IM) et contrôle (NaCl 0,9% IM). Un suivi dans le temps a été réalisé afin d’étudier leur récupération de l’anémie, la présence d’effets secondaires au traitement et l’impact d’une administration de fer sur ces réserves. Aucune différence significative n’a été observée entre les deux groupes en ce qui concerne les signes cliniques, l’hématocrite, le pourcentage des polychromatophiles/réticulocytes, la densité cellulaire et le fer de la moelle osseuse, la créatine kinase et le fer plasmatique. La majorité des crécerelles ont présenté une myosite au site d’injection du fer. Nos résultats suggèrent qu’une administration de 10 mg/kg de fer dextran IM n’a pas d’effet sur l’érythropoïèse des rapaces souffrant d’anémie par perte de sang externe aiguë, qu’elle provoque une légère inflammation au site d’injection et qu’elle n’influence pas les réserves de fer. Le comptage des réticulocytes en anneau et des polychromatophiles semble être deux méthodes équivalentes. / A 10 mg/kg intramuscular (IM) administration of iron dextran is a common empirical treatment recommended in avian medicine for hemorrhage and anemia. The purpose of this study was to evaluate the effects of this treatment on anemia in birds of prey. Two kinds of specimen were used: the American kestrel (Falco sparverius) where an acute external blood loss anemia was created (with two phlebotomies of 20-40 % of the total blood volume at 6 hours interval) and other various species of wild birds of prey suffering from different types of anemia. All subjects were randomized into a treatment (iron dextran 10 mg/kg IM) or a control (NaCl 0,9 % IM) group. Monitoring was carried out to evaluate the evolution of the anemia, presence of side effects and impact of an iron administration on their iron reserve. No significant differences were observed between the two treatment groups for clinical signs, packed cell volume, the percentage of reticulocytes/polychromatophilic erythrocytes, bone marrow cellularity and iron, plasmatic iron and creatine kinase. Most kestrels had a myositis at the iron injection site. Our results suggest that an IM injection of 10 mg/kg iron dextran has no effect on raptor erythropoiesis after an acute external blood loss anemia, that it has no effect on iron reserve, and that it can cause mild inflammation at the injection site. The polychromatophilic erythrocytes and the reticulocytes ring form count were two equivalent methods.

Les polyphénols, micronutriments abondants dans notre alimentation, sont bien connus pour leurs propriétés antioxydantes et anti-inflammatoires et leur consommation a été associée à un moindre risque de maladies chroniques (maladies cardiovasculaires, cancers…). Ces composés suscitent un intérêt croissant dans le domaine de la santé digestive. En effet, les polyphénols sont faiblement absorbés au niveau de l’intestin grêle et sont présents en quantité relativement importante dans le côlon. Les polyphénols et leurs métabolites pourraient donc exercer des effets bénéfiques à ce niveau. Des études expérimentales récentes suggèrent que les polyphénols pourraient aider à prévenir ou retarder la progression de l’inflammation colique. Le raisin est l’un des fruits les plus riches en polyphénols. Divers co-produits du raisin ont montré des effets bénéfiques vis-à-vis de différentes situations d'inflammation, effets souvent attribués à leur richesse en composés polyphénoliques. Les objectifs de cette thèse étaient tout d’abord d’évaluer l’impact du régime de base sur le développement de l’inflammation colique induite par le sulfate de dextran sodique (DSS) chez le rat (1) puis d’évaluer les effets d’une supplémentation nutritionnelle en extraits de marc de raisin (EMR) riches en polyphénols dans la prévention de l’inflammation colique induite par le DSS (2). Pour cela, des rats Wistar ont été nourris ad libitum durant 21 jours avec un régime standard ou un régime semi-synthétique (1) ou les animaux ont été nourris avec un régime semi-synthétique supplémenté ou non avec un EMR (2). Dans tous les cas, l’inflammation colique a été induite par administration de DSS à 4% dans l’eau de boisson pendant les 7 derniers jours de l’expérimentation. Les effets ont été évalués au niveau colique par analyse histologique, détermination de différents marqueurs de l'inflammation et de la défense antioxydante et évaluation de l'expression de différents gènes impliqués dans l’inflammation et le stress oxydant.La consommation préventive de trois EMRs, issus de deux cépages différents (Alicante et Pinot) exerce des effets bénéfiques sur le développement de l’inflammation colique induite par le DSS. Globalement, la consommation à titre préventif d’EMRs prévient la perte de poids, retarde l’apparition des symptômes de la maladie et limite le développement des atteintes tissulaires induites par le DSS. Les EMRs atténuent l’inflammation comme en témoigne la diminution de l’activité de la MPO et le maintien des taux coliques en cytokines pro-inflammatoires au niveau des animaux témoins. De plus, ces EMRs modulent les activités des enzymes antioxydantes. Les EMRs limitent également la surexpression de plusieurs gènes impliqués dans la réponse inflammatoires et le stress oxydant (COX-2, iNOS, ICAM-1, MMP-9…). De plus, nous avons montré que les EMRs provenant du cépage Alicante exercent des effets protecteurs plus marqués que l’EMR Pinot.Ainsi, ces résultats soulignent d’une part l’influence du régime alimentaire de base dans l’induction de l’inflammation colique. D’autre part, la consommation à titre préventif d’EMRs exerce des effets protecteurs sur le développement de l'inflammation colique induite par le DSS via la modulation de marqueurs de l’inflammation et de la défense antioxydante. Ces résultats pourraient permettre d’envisager de nouvelles stratégies nutritionnelles dans la prévention des maladies inflammatoires de l’intestin. / Polyphenols are abundant micronutrients in plant foods, where they have been associated with lower risk of chronic diseases from cancer to cardiovascular disease. The beneficial health effects of polyphenols have been attributed to their antioxidant and anti-inflammatory properties. Several studies point to a promising role of these micronutrients in inflammatory bowel disease (IBD), as given that a large fraction of dietary polyphenols reach the colon, polyphenols and their metabolites could exert beneficial effects locally at this level. Recent experimental data suggest that polyphenols could help prevent or delay the progression of intestinal inflammation. Grape is one of the richest sources of polyphenols, and various grape products have demonstrated beneficial effects in various chronic diseases. These effects are often attributed to grape polyphenolic compounds.This thesis aimed (1) to evaluate the impact of purified and non-purified basal diets on the development of dextran sodium sulfate (DSS)-induced colitis in the rat, then (2) to evaluate the effects of preventive consumption of polyphenol-rich red grape pomace extracts (GPEs) on DSS-induced colitis. Rats were fed for 21 days with (1) a non-purified or purified diet or (2) GPE-enriched purified diet, and colitis was induced by DSS administration in drinking water (4% w/v) during the last 7 days of the experimental design. The effects on colitis development were assessed by histological analysis, determination of various markers of inflammation and oxidative stress, and evaluation of the expression of various genes implicated in this disorder.DSS induced a more marked colitis in rats receiving the purified diet than the non-purified diet. Indeed, rats receiving the purified diet, the inflammation was characterized by decreased appetite and weight gain, early onset of disease (diarrhea and rectal bleeding), and colon shortening. In rats fed the purified diet, DSS also induced marked histological colonic damage and increased MPO activity. In these animals, DSS also modulated oxidative status by affecting antioxidant enzyme activities. Furthermore, DSS-induced inflammation was associated with increased pro-inflammatory cytokine levels and decreased anti-inflammatory cytokine levels in colonic tissue, together with upregulation of the expression of various genes (iNOS, ICAM-1 and MMP-9).Preventive consumption of three GPEs from two different grape varieties (Alicante and Pinot) showed beneficial effects on DSS-induced colitis development. Overall, preventive dietary GPE supplementation delayed the onset of colitis symptoms and limited the extent of weight loss and colonic mucosa damage. GPE administration reduced inflammation (as evidenced by a decrease in MPO activity) and kept colonic pro-inflammatory cytokines at near-control levels. In addition, the three GPEs modulated antioxidant enzyme activities and limited the overexpression of several genes involved in DSS-induced inflammatory response and oxidative stress (COX-2, iNOS, ICAM-1, MMP-9). Moreover, Alicante-variety GPEs exerted stronger protective effects than Pinot-variety GPEs.These results highlighted (1) the influence of basal diet on induction of colonic inflammation and (2) that preventive consumption of GPEs exerted protective effects against colitis development by modulating inflammatory processes and oxidative stress markers. These findings open up perspectives for new preventive nutritional strategies in colonic inflammation management.

This diploma thesis deals with the study of physical hydrogels based on positively-charged polyelectrolyte. The study is to investigate the interaction of selected positively-charged polyelectrolytes with oppositely charged surfactants in water and in physiologicla saline solution (0.15 M NaCl). The influence of the process for preparing hydrogels. Hydrogels were prepared by dry or wet. Were tested solubilization abilities hydrogels prepared using the hydrophobic dye oil red O were also measured rheological properties of the hydrogels prepared using frequency oscillatory tests and flow tests, depending on the concentration of the polymer or surfactant. For the rheological experiments suggest that chitosan is capable of forming rigid hydrogels with better mechanical properties than the dextran in the presence of both surfactants. Selected samples were also carried out experiments using fluorescent sold prodan, nile red and -naphthol as fluorescent probes. And in selected experiments was determined by solids content in percentage depending on the concentration used polyelectrolytes or surfactants.

O Brasil é atualmente o maior produtor e exportador mundial de açúcar e a aguardente de cana aqui produzida é a terceira bebida destilada mais consumida no mundo. Contudo, estes produtos ainda têm a sua qualidade afetada pela presença de Dextranas. Devido à sua origem (produto secundário do metabolismo bacteriano) e por conta das suas propriedades físico-químicas, as dextranas constituem um importante meio para a avaliação da qualidade do açúcar. No âmbito industrial, as dextranas podem causar diversos problemas ao setor alimentício que utiliza o açúcar como matéria-prima, além de estarem diretamente relacionadas à formação de precipitados na aguardente de cana adoçada. Este trabalho apresenta o primeiro perfil da distribuição de massa molar das dextranas presentes no açúcar brasileiro em função dos seus valores de Mn, Mw, Mz e polidispersividade, os quais exercem influência significativa sobre suas características físico-químicas. Estes parâmetros foram determinados via cromatografia líquida de exclusão por tamanho. O perfil de distribuição de massa molar traçado exibiu, majoritariamente, a presença de dois grupos de dextranas com valores de Mw médios de 5,0 x 106 e 4,8 x 104 Da, e, ocasionalmente, a presença de dextranas que foram classificadas num terceiro grupo com massas molares da ordem de 105 Da. Através deste perfil, foram avaliadas, em sistemas modelo aguardente-dextrana, as influências dos fatores temperatura, acidez, presença dos íons metálicos CuII, FeIII, CaII e MgII e incidência de luz sobre a velocidade de formação dos depósitos de dextranas na aguardente de cana. Demonstrou-se que a acidez e a temperatura foram os fatores que mais influenciam na velocidade de precipitação das dextranas em aguardentes de cana adoçadas. / Brazil is the largest producer and exporter of sugar in the world, and the cachaça is the third most produced distilled beverage in the world. However, these products have their quality affected by the presence of dextrans. Because of its origin (a secondary compound of bacterial metabolism) and due to its physical-chemical properties, the dextrans are an important indicator to assess the sugar quality. Dextrans can lead to problems in processed food production, and it has a strong relation with insoluble deposits in sugared sugar cane spirits. The dextran molecular mass distribution profile in terms of Mn, Mw Mz and polydispersity in Brazilian sugars are reported for the first time. The analyses were accomplished by Size-exclusion chromatography, using a refraction index detector. In most of the sugar samples, it was possible to identify two major groups of dextrans with Mw averages of 5.0 x 106 e 4.8 x 104 Da. A third group of dextrans with Mw of 105 was occasionally observed. With this data, model systems were built to assess the influence of the temperature, acidity, presence metalic ions CuII, FeIII, CaII, and MgII, light incidence in relation of dextran precipitation velocities. It is demonstrated that factors temperature and acidity are the most influential in the dextran precipitation velocity in sugar cane spirits.

Orientador: Silvio Roberto Andrietta / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-09-11T21:08:51Z (GMT). No. of bitstreams: 1 Aquino_DeniseSilvade_M.pdf: 2817268 bytes, checksum: 75e30246006dba478e363bb0b37da638 (MD5) Previous issue date: 2006 / Resumo: Dextranas são polissacarídeos produzidos pela bactéria pertencente à família Lactobacileae constituídos de moléculas de glicose unidas por ligações a-(1-6) na cadeia principal e ligações a-(1-4), a-(1-3) e a-(1-2) nas ramificações. A enzima dextranasacarase, responsável por sua síntese, é extracelular e tem a sacarose como principal indutor. Este biopolímero possui aplicações nas indústrias farmacêuticas, químicas e de alimentos. Na indústria farmacêutica é que a dextrana tem a sua maior aplicação. A dextrana de baixa massa molecular, dextrana clínica, é utilizada como expansor volumétrico sanguíneo e como facilitador da fluidez do sangue. Este trabalho teve como objetivo otimizar o processo de produção de dextrana por três novas linhagens de bactérias denominadas 4-03, 4-30 e 4-26 isoladas da cana-de-açúcar, dentro deste objetivo principal estão incluídos a caracterização da estrutura de cadeia destes biopolímeros e a identificação das linhagens das bactérias isoladas. Para a otimização, tanto da produção de dextrana como da produção de dextrana-sacarase, realizaram-se ensaios em frascos agitados, analisando a influência das seguintes variáveis: concentração de tampão (controle do pH), concentração de substrato (sacarose) e concentração da fonte de nitrogênio (extrato de levedura). Conduziram-se os ensaios de otimização com base em planejamento experimental fatorial e análise de superfície de resposta. As linhagens 4-26 e 4-30 apresentaram modelos estatisticamente significativos, portanto, podem ser utilizados na previsão da composição do meio de fermentação para produção da dextrana-sacarase. Para a otimização da produção de dextrana, somente a linhagem 4-26 mostrou variação significativa estatisticamente das variáveis respostas frente ás variáveis estudadas na região avaliada. Realizaram-se ensaios para a obtenção da dextrana a qual teve sua estrutura de cadeia determinada utilizando o método da perioxidação e o método da degradação de Smith. A primeira metodologia consiste em determinar os tipos e as proporções das ligações a-(1-6), a-(1-4) e a-(1-2), e a-(1-3) por meio do consumo do oxidante e produção de ácido quando as dextranas são sujeitas a uma oxidação com periodato. A segunda metodologia citada, consiste na oxidação do polissacarídeo seguida de redução ao poliálcool correspondente e por fim realiza-se hidrólise ácida gerando fragmentos de Dgliceraldeído, característico de ligações a- (1,2), D-glicose, característico de ligações a-(1,3), eritritol, característico de ligações a- (1,4), glicerol e glicoaldeído, característicos de ligações a- (1,6) e terminal não-redutor. Quando compara-se os dois métodos de determinação da estrutura de cadeia da dextrana, a solubilidade em água da dextrana formada pela linhagem 4-03 é confirmada, pois a sua cadeia em ambas as análises apresentou uma maior porcentagem das ligações a-(1,6), característica contrária a goma produzida pela linhagem 4-30, que apresenta-se de forma insolúvel por ter uma cadeia ramificada. O resultado para o biopolímero formado pela linhagem 4-26 apresentou-se os mesmos valores para as duas metodologias, porém no método da degradação de Smith sua estrutura não aproximou-se da dextrana padrão / Abstract: Dextran is a polysaccharide produced by bacteria of the Lactobacillaceae family and it consists of D-glucose monomeric units linked at the position a-(1,6) in the linear chain and a-(1-4), a-(1-3) and a-(1-2) positions at the branching points. The enzyme dextransucrase, responsible for dextran synthesis, is extracellular and has sucrose as its main inductor. This biopolymer is used by the pharmaceutical, chemistry and the food industry. Dextran has its main application in the pharmaceutical industry. The low molecular weight dextran, the clinical dextran, is used as blood volume expander and blood flow improver. This work had as objective to optimize the dextran production by three new bacteria strains named 4-03, 4-26 and 4-30 isolated from sugar cane, into this main objective are including the characterization the structure of the chain of these bacteria biopolymers and to identification bacteria strains isolated. The influence of the following variable was analyzed for the dextransucrase and dextran production optimization: buffer (pH control), substrate (sucrose) and nitrogen source (yeast extract) concentrations. The experimental assays were performed on the basis of factorial design and response surface techniques. The strains 4-26 and 4-30 presented statically significant models, therefore, these models may be used for predict the optimum composition of the fermentation medium for dextransucrase production. Only strain 4-26 showed statically significant variation of the dependent variables in the evaluated region dextran production optimization. The dextran structure of the three strains was determined by the periodate oxidation and Smith degradation methods. The first methodology consist in to determine kinds and proportions of the a-(1,6), a-(1-2) e a-(1-4) e a-(1-3) linkages by the consumption of oxidant and the production of acid when the dextran is subject to periodate oxidation analysis. The second methodology consists in the oxidation of the polysaccharide followed by reduction and hydrolysis with dilute acid which produces characteristic fragments: D-glyceraldehydes, characteristic of the a-(1,2) linkages, D-glucose, characteristic of the a-(1,3) linkages, erythritol, characteristic of the a-(1,4) linkages and glycerol or glycolaldehyde, characteristic of the a-(1,6) linkages and no reducing terminal. The results obtained confirmed the high solubility of the dextran produced by strain 4-03 due to its high proportion of the a-(1,6) linkages in contrast with gum produced by strain 4- 30 that is highly insoluble due to its branched chain. The biopolymer produced by strain 4- 26 presented the same values for the both methodologies, however, the Smith degradation result showed that its structure is not close to the standard dextran / Mestrado / Desenvolvimento de Processos Biotecnologicos / Doutor em Engenharia Química