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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Polissacar?deos sulfatados de interesse farmacol?gico no camar?o litopenaeus schimitti

Santos, Vanessa Olinto dos 12 June 2006 (has links)
Made available in DSpace on 2014-12-17T14:03:41Z (GMT). No. of bitstreams: 1 VanessaOS.pdf: 1126102 bytes, checksum: dba464c890585c6be32a3fd2dc600a81 (MD5) Previous issue date: 2006-06-12 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Sulfated Polysaccharides with unique chemical structures and important biological activities has been found in a diversity of sea invertebrates. For that, to exist a huger interest on the biotechnology field in the research theses sulfated compounds isolated from sea organisms. Despite the privileged brazilian position for these compounds attainment, there are still a few scientific informations about the isolated substances and their biological activities. A head the displayed, the present work has for objectives, to evaluate the pharmacological properties of the glycosaminoglycans isolated from the sea shrimp Litopenaeus schimitti on homeostasis, blood coagulation, leukocytes migration and platelet/leukocyte adhesion. For this, yhe glycosaminoglycans were extracted from crustacean tissues by proteolysis, fractionation with acetone and later submitted to pharmacological assays. The crustacean tissues showed compounds heparin-like, with anticoagulant activity of 45 IU/mg and 90 IU/mg, respectively. These molecules showed low residual hemorrhagic effects in the tested concentration (100 ?g/mL), when compared to unfractionated commercial heparin (UFH). Another dermatan sulfate-like compound, predominately constituted for disulfated disaccharides, was isolated from crustacean abdomen. This compound showed an efficient effect on leukocytes migration inhibition, in the concentration of 15 ?g/mL, reducing the cellular infiltration in 65% when compared to the controlled animals. In this same concentration, the DS reduced in 60% the protein concentration of the peritoneal exudates. In the concentration, this compound of 0.5 mg/mL, it was capable to reduce in 40% platelet/leukocytes adhesion. Our data demonstrate that these sulfated polysaccharides isolated from the shrimp L. schimitti will can be used as bioactive compounds, appearing as active principles for pharmacological development, anticoagulants and inflammatory response regulators / Polissacar?deos sulfatados com caracter?sticas estruturais distintas e importantes atividades biol?gicas t?m sido encontrados em uma diversidade de invertebrados marinhos. Por isso existe um grande interesse no campo da biotecnologia na pesquisa destes compostos sulfatados isolados de organismos aqu?ticos. No entanto, apesar da posi??o privilegiada do Brasil para a obten??o destes compostos, ainda s?o poucas as informa??es cient?ficas sobre as subst?ncias isoladas e suas atividades biol?gicas. Diante do exposto, este presente trabalho teve por objetivos avaliar os potenciais farmacol?gicos dos glicosaminoglicanos (GAGs) isolados do camar?o marinho Litopenaeus schimitti, sobre a hemostasia, coagula??o sang??nea, migra??o leucocit?ria e ades?o celular. Para isso os GAGs foram extra?dos dos tecidos do crust?ceo mediante prote?lise, fracionamento com acetona e posteriormente submetidos aos ensaios farmacol?gicos. Os tecidos do crust?ceo, abd?men e cefalot?rax, apresentaram compostos semelhantes ? heparina (heparin?ides) com atividade anticoagulante de 45 UI/mg e 90 UI/mg, respectivamente. Estas mol?culas apresentaram baixo efeito hemorr?gico residual na concentra??o de 100 ?g/mL, quando comparada com a heparina comercial n?o fracionada (HNF). Um outro composto semelhante ao dermatam sulfato (DS), constitu?do predominantemente por dissacar?deos dissulfatados foi isolado do abd?men do crust?ceo. Este composto apresentou, na concentra??o de 15 ?g/?L, uma inibi??o significativa (P<0.01) da migra??o leucocit?ria, reduzindo a infiltra??o celular em 65% quando comparado com os animais controle. Nessa mesma concentra??o o DS reduziu em 60% a concentra??o de prote?nas do lavado peritonial. As an?lises qualitativas da composi??o celular do exudato peritonial foram similares ao encontrado para os animais controles em todas as concentra??es testadas. Na concentra??o de 0,5 mg/mL foi capaz de reduzir em 40% a ades?o das plaquetas aos leuc?citos. Os dados obtidos demonstram que estes polissacar?deos sulfatados isolados do camar?o L.schimitti podem vir a ser utilizados como compostos bioativos, podendo surgir como princ?pios ativos para o desenvolvimento de f?rmacos, anticoagulantes e moduladores da resposta inflamat?ria
52

Distinct Modulatory Actions Enable Network Neuron Recruitment and Regulation

Fahoum, Savanna-Rae Hakam 21 July 2023 (has links)
No description available.
53

Effects of Aquatic Acidification on Calcium Uptake in White River Shrimp Litopenaeus setiferus Gills

Jacobs, Maria-Flora 01 January 2019 (has links)
Previous research regarding aquatic acidification has examined the protonation of the carbonate and does not consider calcium to be a limiting factor. This is the first study to suggest that pH may affect the uptake of calcium in crustacean gills. This project describes ion transport mechanisms present in the cell membranes of white river shrimp Litopenaeus setiferus gill epithelium, and the effects of pH on the uptake of calcium by these means. Partially purified membrane vesicles (PPMV) of shrimp gills were prepared through a homogenization process that has been used previously to define ion transport in crab and lobster gill tissues. In the current study, shrimp gill PPMV calcium uptake at 50 µM, and 250 µM was greatest at pH 7.0 (p=0.01, p=0.0001). A valinomycin/K+ induced membrane potential (PD) at pH 7.0 significantly increased (p=0.003) calcium uptake from that observed in the absence of a PD. An induced PD at pH 8.0 significantly increased (p=0.003) calcium uptake from that observed in the absence of a PD, however, was not significantly greater than uptake at pH 7.0 in the presence of a PD (p=0.05). Amiloride (2mM) treatments, and amiloride (2mM) + verapamil (100µM) cocktail treatments showed significant decrease in calcium uptake from the control (p=0.03), however, they were not different from each other. This indicates an electrogenic carrier with two driving forces: calcium concentration, and asymmetric exchange stoichiometry.
54

Exploitation et utilisation des invertébrés marins durant la Protohistoire sur le territoire continental et littoral Manche-Atlantique français / Exploitation and use of marine invertebrates during the Protohistory on the continental and littoral Channel-Atlantic area in France. / Explotación y utilización de invertebrados marinos durante la Protohistoria en la zona continental y litoral de la Mancha-Atlántica (Francia)

Mougne, Caroline 25 February 2015 (has links)
Ce travail porte sur l'utilisation et l'exploitation des invertébrés marins (mollusques, crustacés et échinodermes) durant la Protohistoire sur les côtes de la Manche et de l'Atlantique en France. Il repose sur l'inventaire de 197 sites ayant livré ce type de faune. 32 ont fait l'objet d'une étude archéomalacologique, dont 17 dans le cadre de cette thèse. Les résultats obtenus permettent d'aborder des thématiques variées, comme les environnements exploités, l'économie de subsistance (mode alimentaire, spécificité géographique, réseau d'échange), l'artisanat (teinture, parure, matériau de construction, etc.) et les pratiques funéraires et cultuelles (dépôt, repas rituels). L'étude des invertébrés marins contribue ainsi à une meilleure compréhension des systèmes socio-économiques et culturels des communautés littorales et continentales durant la Protohistoire. / This work deals with the use and exploitation of marine invertebrates (molluscs, crustaceans and echinoderms) during the Protohistory on the Channel and Atlantic coasts in France. It relies on the inventory of 197 sites characterized by the presence of this type of fauna. Some archaeomalacological studies have been realized on 32 of these sites, of which 17 during this thesis. The results allow to approach various themes, such as the environments exploited, the subsistence economy (food, geographical variations, exchange network), crafts (dyeing, beads, building material, etc.) and funeral and ritual practices (hoard, ritual meal). The study of the marine invertebrates thus contributes to a better understanding of the socio-economical and cultural systems of the littoral and continental communities during the Protohistory. / Este trabajo se centra en el uso y explotación de los invertebrados marinos (moluscos, crustáceos y equinodermos) durante la Protohistoria en la costa de la Mancha y Atlántica de Francia. La investigación se basa en un inventario de 197 sitios arqueológicos con presencia de restos malacológicos, sobre 32 de ellos se ha realizado un estudio arqueomalacológico, de los cuales 17 se han desarrollado e incluido en el contexto de esta tesis doctoral. Los resultados obtenidos se han orientado a tratar una variedad de cuestiones, como el medioambiente explotado, la economía de subsistencia a partir de diferentes perspectivas (la alimentación, las especificaciones geográfica, o las redes de intercambio), la producción artesanal (tintes, elementos de adorno o material de construcción), o las prácticas funerarias y rituales (elementos de ajuar, comidas rituales). El estudio de los invertebrados marinos contribuye así a una mejor comprensión de los sistemas culturales y socio-económicos de las comunidades costeras y también continentales a lo largo de la Protohistoria.
55

Functional Characterization of a Putative Disaccharide Membrane Transporter in Crustacean Intestine

Likely, Rasheda S 01 January 2014 (has links)
The mechanisms of transepithelial absorption of dietary sucrose in the American lobster, Homarus americanus, were investigated in this study to determine whether sugars can be transported across an animal gut intact or as monosaccharides following hydrolysis. Lobster intestine was isolated and mounted in a perfusion chamber to characterize the mechanisms of mucosal to serosal (MS) 14C -sucrose transport across the intestine MS fluxes were measured by adding varying concentrations of 14C-sucrose to the perfusate which resulted in a hyperbolic curve following Michaelis-Menten kinetics. The kinetic constants of the proposed sucrose transporter were KM = 15.84 ± 1.81 µM and Jmax = 2.32 ± 0.07 ρmol cm-2min-1. The accumulation of 14C-sucrose in the bath in the presence of inhibitors, phloretin, phloridzin, and trehalose was observed. Inhibitory analysis showed that phloridzin, an inhibitor of Na+-dependent mucosal glucose transport, decreased MS 14C-sucrose transport suggesting that MS 14C-sucrose radioactive flux may partially involve an SGLT-1-like transporter. Phloretin, a known inhibitor of Na+-independent basolateral glucose transport, decreased MS 14C-sucrose transport, suggesting that some 14C-sucrose radioactivity may be transported to the blood by a GLUT 2-like carrier. Decreased MS 14C-sucrose transport was also observed in the presence of trehalose, a disaccharide containing D-glucose moieties. Thin-layer chromatography (TLC) was used to identify the chemical nature of radioactively labeled sugars in the bath following transport. TLC revealed 14C-sucrose was transported across the intestine largely as an intact molecule with no 14C-glucose or 14C-fructose appearing in the serosal bath or luminal perfusate. Bath samples evaporated to dryness and resuspended disclosed only 15% volatile metabolites. Results of this study strongly suggest that disaccharide sugars can be transported intact across animal intestine and provide support for the occurrence of a disaccharide membrane transporter that has not previously been functionally characterized.

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