• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 3
  • 2
  • 2
  • Tagged with
  • 11
  • 11
  • 4
  • 4
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 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.
1

Expression of C184M in primary cardiac myofibroblasts and its role in contractility and collagen production in NIH 3T3 fibroblasts

Nazari, Mansoreh 21 August 2009 (has links)
Cardiac fibroblasts are capable of a phenotype shift to myofibroblasts and the latter contribute to wound healing and interstitial fibrosis. TGF-β1 signals through R-Smads and Co-Smad proteins and modulates fibrillar collagen deposition. It also influences myofibroblast cells contractility, which they confer torsional forces on the surrounding matrix. c-Ski plays an inhibitory role in TGF-β1 signaling. C184M is a 27 kDa protein that is a novel cytosolic partner of c-Ski. c-Ski-C184M complexes may negatively regulate TGF-β1 signaling via sequestering R-Smad in the cytosol, however, the role of C184M in cardiac fibrosis is unknown. Herein we characterize the expression of C184M and explore its role in TGF-β1 signaling. We found that C184M is expressed in P0 primary fibroblasts, P1 and P2 cardiac myofibroblasts and as well in NIH 3T3 cells. Western blot analysis revealed that the C184M is not responsive to TGF-β1 treatment (10ng/ml, 12, 24 and 48hr treatment) and that Smad3 overexpression does not influence expression of C184M protein in P1 cardiac myofibroblasts. In the presence of overexpressed C184M, immunofluorescence studies indicated a shift in localization of Smad3 from a diffuse cytosolic pattern to a distinctly punctuate cytosolic pattern. C184M overexpression abrogates the effects of TGF-β1 mediated increased collagen synthesis in NIH 3T3 cells. Further, C184M is involved in reduction of contractility of NIH 3T3 cells.
2

Expression of C184M in primary cardiac myofibroblasts and its role in contractility and collagen production in NIH 3T3 fibroblasts

Nazari, Mansoreh 21 August 2009 (has links)
Cardiac fibroblasts are capable of a phenotype shift to myofibroblasts and the latter contribute to wound healing and interstitial fibrosis. TGF-β1 signals through R-Smads and Co-Smad proteins and modulates fibrillar collagen deposition. It also influences myofibroblast cells contractility, which they confer torsional forces on the surrounding matrix. c-Ski plays an inhibitory role in TGF-β1 signaling. C184M is a 27 kDa protein that is a novel cytosolic partner of c-Ski. c-Ski-C184M complexes may negatively regulate TGF-β1 signaling via sequestering R-Smad in the cytosol, however, the role of C184M in cardiac fibrosis is unknown. Herein we characterize the expression of C184M and explore its role in TGF-β1 signaling. We found that C184M is expressed in P0 primary fibroblasts, P1 and P2 cardiac myofibroblasts and as well in NIH 3T3 cells. Western blot analysis revealed that the C184M is not responsive to TGF-β1 treatment (10ng/ml, 12, 24 and 48hr treatment) and that Smad3 overexpression does not influence expression of C184M protein in P1 cardiac myofibroblasts. In the presence of overexpressed C184M, immunofluorescence studies indicated a shift in localization of Smad3 from a diffuse cytosolic pattern to a distinctly punctuate cytosolic pattern. C184M overexpression abrogates the effects of TGF-β1 mediated increased collagen synthesis in NIH 3T3 cells. Further, C184M is involved in reduction of contractility of NIH 3T3 cells.
3

DEVELOPING A LOW COST BIOLOGICAL ADDITIVE MANUFACTURING SYSTEM FOR FABRICATING GEL EMBEDDED CELLULAR CONSTRUCTS.

Minck, Justin Stewart 01 June 2019 (has links)
Organ transplantation has made great progress since the first successful kidney transplant in 1953 and now more than one million tissue transplants are performed in the United States every year (www.organdonor.gov/statistics-stories, 2015). However, the hope and success of organ transplants are often overshadowed by their reputation as being notoriously difficult to procure because of donor-recipient matching and availability. In addition, those that are fortunate enough to receive a transplant are burdened with a lifetime of immunosuppressants. The field of regenerative medicine is currently making exceptional progress toward making it possible for a patient to be their own donor. Cells from a patient can be collected, reprogrammed into stem cells, and then differentiated into specific cell types. This technology combined with recent advances in 3D printing provides a unique opportunity. Cells can now be accurately deposited with computerized precision allowing tissue engineering from the inside out (Gill, 2016). However, more work needs to be done as these techniques have yet to be perfected. Bioprinters can cost hundreds of thousands of dollars, and the bioink they consume costs thousands per liter. The resulting cost in development of protocols required for effective tissue printing can thus be cost-prohibitive, limiting the research to labs which can afford this exorbitant cost and in turn slowing the progress made in the eventual creation of patient derived stem cell engineered organs. The objective of my research is to develop a simple and low-cost introductory system for biological additive manufacturing (Otherwise known as 3D bioprinting). To create an easily accessible and cost-effective system several design constraints were implemented. First, the system had to use mechanical components that could be purchased “off-the-shelf” from commonly available retailers. Second, any mechanical components involved had to be easily sterilizable, modifiable, and compatible with open-source software. Third, any customized components had to be fabricated using only 3D printing and basic tools (i.e. saw, screwdriver, and wrench). Fourth, the system and any expendable materials should be financially available to underfunded school labs, in addition to being sterilizable, biocompatible, customizable, and biodegradable. Finally, all hardware and expendables had to be simple enough as to be operated by high school science students.
4

Characterization of a murine gammaherpesvirus in vitro latency system

Mutyambizi, Kudakwashe 04 January 2010 (has links)
The human gammaherpesviruses EBV and KSHV realize their oncogenic potential during latent infection. The species specificity of the human gammaherpesviruses has hindered the study of latency in animal models. Murine gammaherpesvirus MHV-68 (MHV-68) may be used as a representative gammaherpesvirus for the study of latency. The goal was to establish an in vitro model of MHV-68 latency using replication defective MHV-68. ORF50 has been identified as the major viral trans-activator essential for entry into the lytic replication cycle and necessary and sufficient for reactivation of MHV-68 virus from latency. ORF50 null mutants (A50) can theoretically be used to infect cells in vitro to facilitate an analysis of virus gene expression and episome maintenance during latency. In this project A50 mutants containing the luciferase or green fluorescence protein (GFP) under OW50 promoter control were used to infect a variety of cell types. 3T3 fibroblasts are a permissive cell line and were used for an initial characterization of the ability of A50 MHV-68 to establish latency. B lymphocytes and macrophages are the major reservoirs of persistence in vivo thus the ability of A50 mutants to establish latency in NSO B and RAW macrophage cell lines was explored. Latency was readily established and maintained in 3T3 and RAW cells. The low infectability of NSO B- cells restricted the utility of this cell line in studies of latency. Examination of patterns of lytic and latent transcription in 3T3 and RAW cells coordinately infected with A50 MHV-68 revealed reactivation efficiencies of 40-60%. Following long-term passage A50 exhibited stable transcription of two latency related genes M2 and ORF73, with episomal maintenance of the viral genome, in the absence of contaminating lytic infection. The results demonstrate the utility of A50 mutants for studies of gammaherpesvirus latency in vivo.
5

Remodelação cromatínica, anomalias cromossômicas e morte celular em condições de inibição de deacetilases de histonas em células HeLa e 3T3 / Chromatin remodeling, chromosome abnormalities and cell death under histone deacetylase inhibition in HeLa and 3T3 cells

Felisbino, Marina Barreto, 1988- 20 August 2018 (has links)
Orientador: Maria Luiza Silveira Mello / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-20T21:08:55Z (GMT). No. of bitstreams: 1 Felisbino_MarinaBarreto_M.pdf: 5744960 bytes, checksum: 792f3ed20bbe7d53c917089733be679f (MD5) Previous issue date: 2012 / Resumo: O ácido valproico (VPA) é um potente anti-convulsante conhecido como inibidor de deacetilases de histonas (HDACi) de classe I em diversos tipos celulares. Buscando conhecer se a estrutura cromatínica se alteraria quando da ação de HDACi, investigamos a supraorganização cromatínica de células tumorais HeLa e de células NIH 3T3, estas últimas caracterizadas por apresentarem áreas de heterocromatina conspícuas, sob tratamento com VPA. Essas informações foram associadas a da atividade enzimática de HDACs assim como do nível de acetilação das histonas H3 nesses modelos celulares tratados por VPA. As frequências de anomalias cromossômicas, morte celular e índices mitóticos também foram investigados. As células tratadas com VPA nas concentrações 0,05, 0,5 e 1,0 mM por 1-24 h foram submetidas à reação de Feulgen e analisadas através de microespectrofotometria de varredura automática e microscopia óptica. Western blots, análises enzimáticas e ensaio TUNEL também foram utilizados neste estudo. Células tratadas com tricostatina A (TSA), uma HDACi de atividade mais ampla do que o VPA, foram utilizadas como controles positivos. Em todas as condições de tratamento com VPA e TSA foi demonstrada descompactação cromatínica acompanhada de diminuição na atividade de HDACs e aumento na acetilação de histona H3. Essa alteração textural cromatínica também atingiu áreas heterocromáticas de células NIH 3T3. Nenhuma alteração nas frequências de anomalias cromossômicas, índices mitóticos e morte celular foi observada nesses modelos celulares nas condições relatadas, embora tenha ocorrido um aumento de fragmentação de DNA em células HeLa tratadas com VPA por 24 h e por TSA a partir de 4 h. Diminuição na proliferação celular nas células HeLa ocorreu apenas sob tratamento com VPA 5,0 mM por 48 h. Os resultados indicam que o VPA e a TSA promovem remodelação cromatínica em células tumorais HeLa e em células fibroblásticas NIH 3T3, que pode ser atribuída à sua ação de HDACi. Não se pôde descartar, porém, que o VPA atue sobre outras proteínas nucleares, cuja expressão poderia se apresentar diminuída sob sua ação / Abstract: Valproic acid (VPA) is a potent anticonvulsant that inhibits class I histone deacetylases (HDACi) in several cell types. Seeking to know whether the chromatin structure would change when the action of HDACi, we investigated whether VPA would affect chromatin supraorganization of tumoral HeLa cells and NIH 3T3 cells, this latter characterized by presenting areas of conspicuos heterochromatin. This information was associated with enzymatic activity of HDACs as well as the level of H3 histone acetylation in these cell models treated with VPA. The frequency of chromosome abnormalities and cell death and mitotic indices were also investigated. VPA-treated cells at concentration 0.05, 0.5 and 1.0 mM for 1-24 h were subjected to the Feulgen reaction and analysed by automatic scanning microspectrophotometry and optical microscopy. Western blots, enzymatic analysis and TUNEL assay were also performed in this study. Trichostatin A (TSA)-treated cells, an HDACi whose activity is broader than VPA, were used as positive control. Chromatin decondensation was demonstrated under all TSA and VPA treatments and was associated with decrease in HDAC activity and with increase in the level of H3 histone acetylation. This chromatin textural change also affected heterochromatic areas of NIH 3T3 cells. No changes in chromosome abnormalities, mitotic indices or morphologically identified cell death were found in both cellular models with the VPA treatment conditions mentioned above, although there was an increase of DNA fragmentation after a 24 h-VPA treatment and a 4 h-TSA treatment in HeLa cells. Decrease in cell proliferation in HeLa cells ocurred only under a 5.0 mM 48 h-VPA treatment. The results indicate that VPA and TSA promote chromatin remodeling in tumoral HeLa cells and fibroblastic NIH 3T3 cells, which may be attrituted to their HDACi action. It may not be discarded, however, that VPA acts on other nuclear proteins whose expression could be reducted under its action / Mestrado / Biologia Celular / Mestre em Biologia Celular e Estrutural
6

Mechanics of Fibroblast Migration: a Dissertation

Munevar, Steven 09 May 2003 (has links)
Cell migration involves complex mechanical interactions between cells or between cells and the underlying substrate. Using a newly developed technique, "traction force microscopy", I have been able to visualize the dynamic characteristics of mechanical forces exerted by migrating fibroblasts such as magnitude, direction, and shear. For NIH 3T3 fibroblasts, I found that the lamellipodium provides nearly all of the force necessary for cell migration. A high shear zone separates the lamellipodium from the remainder of the cell body, suggesting that they are mechanically distinct entities. The timing of the tractions at the leading edge, as well as the spatial distribution, bears no apparent relationship to concurrent local protrusive activities, yet changes in traction force patterns often precede changes in migration direction. In H-ras transformed cells I found isolated regions of weak, transient traction forces in pseudopods all along the cell that appeared to act against one another. The resulting shear pattern suggested that there were multiple disorganized mechanical domains. These results support a frontal towing model for cell migration where the dynamic traction forces at the leading edge served to actively pull the cell body forward. In H-ras transformed cells, the weak poorly coordinated traction forces coupled with weak cell substrate-adhesions were likely responsible for the abnormal motile behavior of these cells. To probe the mechanical interactions beneath various regions of migrating fibroblasts, a cell substrate inhibitor (GRGDTP peptide) was locally applied while imaging stress distribution on the substrate utilizing traction force microscopy. I found that both spontaneous and GRGDTP induced detachment of the trailing edge resulted in extensive cell shortening with no change in overall traction force magnitude or cell migration. Conversely, leading edge disruption resulted in a dramatic global loss of traction forces pnor to any significant cell shortening. These results suggested that fibroblasts transmit their contractile forces to the substrate through two distinct types of adhesions. Leading edge adhesions were unique in their ability to transmit active propulsive forces whereas trailing end adhesions created passive resistance during cell migration and readily redistributed their loads upon detachment. I have also investigated how fibroblasts regulate traction forces based on mechanical input. My results showed that stretching forces applied through the flexible substrate induced increases in both intracellular calcium concentration and traction forces in fibroblasts. Treatment with gadolinium, a well known stretch-activated ion channel inhibitor, was found to inhibit both traction forces and cell migration without inhibiting cellular spread morphology or protrusive activities. Gadolinium treatment also caused a pronounced decrease in vinculin and phosphotyrosine concentrations from focal adhesions. Local application of gadolinium to the trailing region had no detectable effect on overall traction forces or cell migration, whereas local application to the leading edge caused a global inhibition of traction forces and an inhibition of migration. These observations suggest that stretch activated entry of calcium ions in the frontal region serves to regulate the organization of focal adhesions and the output of mechanical forces. Together my experiments elucidate how fibroblasts exert mechanical forces to propel their movements, and how fibroblasts utilize mechanical input to regulate their movements.
7

AVALIAÇÃO DA CITOTOXICIDADE DA FASE VAPOR DO ÓLEO ESSENCIAL DE Jasminum officinale EM CALU-3 (ADENOCARCINOMA DE PULMÃO) E 3T3 (FIBROBLASTOS)

Kosmo, Daniele de Fátima 07 July 2017 (has links)
Submitted by Angela Maria de Oliveira (amolivei@uepg.br) on 2018-07-03T18:22:09Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Daniele Kosmo.pdf: 1666129 bytes, checksum: 21d35993408cf04cf3327fefb3c5a4a2 (MD5) / Made available in DSpace on 2018-07-03T18:22:09Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Daniele Kosmo.pdf: 1666129 bytes, checksum: 21d35993408cf04cf3327fefb3c5a4a2 (MD5) Previous issue date: 2017-07-07 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O câncer de pulmão está entre os tipos mais comuns dentre todos os tumores malignos. Sendo a quimioterapia o principal tratamento preconizado, todavia além dos seus diferentes efeitos colaterais, verifica-se a resistência a múltiplos fármacos, referida como a perda da sensibilidade tumoral aos agentes quimioterápicos. Óleos essenciais (OE) podem contornar esta refratariedade dos tumores aos fármacos e se apresentam também como alternativa antitumoral, em especial pela possibilidade de serem administrados por via inalatória. O objetivo deste trabalho foi o de avaliar a citotoxicidade da fase vapor do OE de Jasminum officinale em células Calu-3 (adenocarcinoma de câncer de pulmão humano) e células 3T3 (linhagem padrão de fibroblasto murino) bem como investigar as alterações morfológicas e mecanismo de ação deste OE em Calu-3. Foram realizados ensaios de avaliação metabólica com redução de MTT e ensaio de marcação de proteína com SRB, onde verificou-se a redução da viabilidade celular de maneira dose-dependente. A IC50 estimada para células Calu-3 foi de 1495,57 μg/mL e para as células 3T3 foi de 3795,05 μg/mL. Para investigação das alterações morfológicas associados à citotoxicidade, foram avaliados (1) a morfologia celular com o emprego dos corantes alaranjado de acridina, brometo de etídio; (2) distribuição de células entre as fases do ciclo celular com emprego de iodeto de propídio (PI) por citometria de fluxo; e foi avaliado o potencial inibitório da fase vapor do OE de Jasminum officinale na atividade da glicoproteína P empregando o ensaio de acúmulo de Rodamina 123. Os resultados obtidos indicaram que a morte das células foi causada pelo processo de apoptose tardia, inicial e necrose, com pequena redução da porcentagem de células nas fases sub-G0 e G2/M do ciclo celular. A fase vapor do OE de Jasminum officinale apresenta efeito inibitório sobre a atividade da glicoproteína P em sinergia com a curcumina.Tais resultados sugerem a possibilidade da utilização do OE de Jasminum officinale, em sua fase vapor no tratamento do câncer de pulmão por via inalatória, porém ainda são necessários mais estudos para aprofundar o conhecimento sobre óleos essenciais, frente a células normais e tumorais de pulmão, incluindo os mecanismos envolvidos. / Lung cancer is among the most common types among all malignancies, with an increase of 2% per year in its incidence. Chemotherapy is the main treatment recommended, but in addition cause collateral effects and also resistance to multiple drugs can occur, that is, the loss of tumor sensitivity to chemotherapeutic agents. Essential oils (OE) may be an option for this refractoriness of tumors to drugs and also present as an antitumor alternative, especially for the possibility of being administered by inhalation. The objective of this work was to evaluate the cytotoxicity of the vapor phase of jasmine OE in Calu-3 cells (human lung cancer adenocarcinoma) and 3T3 cells (murine fibroblast control line model). The vapor phase of jasmine OE reduces cell viability in a dose-dependent manner, as demonstrated by the MTT and SRB reduction assays. The estimated IC 50 for Calu-3 cells was 1495.57 μg / mL and for 3T3 cells was 3795.05 μg / mL. The possible effects associated with cytotoxicity, (1) cellular morphology, (2) cell cycle phase distribution and (3) P-glycoprotein activity were evaluated. Results indicated that cell death was caused by the late apoptosis and necrosis, reduction in the percentage of cells in the sub-G0 and G2/M cell cycle phases. The vapor phase of the jasmine oil presented an inhibitory effect on the activity of the glycoprotein P in synergy with curcumin. These results suggest the possibility of the use of the OE of jasmine, in its vapor phase in the treatment lung cancer, by inhalation. Further studies are needed to knowledge about essential oils, especially the so-called alternative, against normal and tumor cells of the lung, included the mechanism involved.
8

Bcl-2 related ovarian killer, Bok, is cell cycle regulated and sensitizes to stress-induced apoptosis

Rodríguez, José M. January 2007 (has links)
Dissertation (Ph.D.)--University of South Florida, 2007. / Title from PDF of title page. Document formatted into pages; contains 82 pages. Includes vita. Includes bibliographical references.
9

Protection by the flavonoids quercetin and luteolin against peroxide- or menadione-induced oxidative stress in MC3T3-E1 osteoblast cells

Fatokun, Amos A., Tome, M., Smith, R.A., Darlington, L.G., Stone, T.W. 26 November 2014 (has links)
No / Potential protective effects of the flavonoids quercetin and luteolin have been examined against the oxidative stress of MC3T3-E1 osteoblast-like cells. Although hydrogen peroxide and menadione reduced cell viability, the toxicity was prevented by desferrioxamine or catalase but not superoxide dismutase, suggesting the involvement of hydrogen peroxide in both cases. Quercetin and luteolin reduced the oxidative damage, especially that caused by hydrogen peroxide. When cultures were pre-incubated with quercetin or luteolin, protection was reduced or lost. Protection was also reduced when a 24 h pre-incubation with the flavonoids was followed by exposure to menadione alone. Pretreating cultures with luteolin impaired protection by quercetin, whereas quercetin pretreatment did not affect protection by luteolin. It is concluded that quercetin and luteolin suppress oxidative damage to MC3T3-E1 cells, especially caused by peroxide. The reduction in protection by pretreatment implies a down-regulation of part of the toxic transduction pathway.
10

Atividades biol?gicas de xilana de sabugo de milho

Silveira, Raniere Fagundes de Melo 25 February 2010 (has links)
Made available in DSpace on 2014-12-17T14:03:32Z (GMT). No. of bitstreams: 1 RaniereFMS.pdf: 3115798 bytes, checksum: 664aaedacd292e8b8c2d08a15e193378 (MD5) Previous issue date: 2010-02-25 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The corn cob is an agricultural by-product still little used, this in part due to the low knowledge of the biotechnological potential of their molecules. Xylan from corn cobs (XSM) is a polysaccharide present in greater quantity in the structure of plant and its biotechnology potential is little known. This study aimed to the extraction, chemical characterization and evaluation of biological activities of xylan from corn cobs. To this end, corncobs were cleaned, cut, dried and crushed, resulting in flour. This was subjected to a methodology that combines the use of alkaline conditions with waves of ultrasound. After methanol precipitation, centrifugation and drying was obtained a yield of 40% (g/g flour). Chemical analysis indicated a high percentage of polysaccharides in the sample (60%) and low contamination by protein (0.4%) and phenolic compounds (> 0.01%). Analysis of monosaccharide composition indicated the presence of xylose:glucose:arabinose:galactose:mannose:glucuronic acid in a molar ratio 50:20:15:10:2.5:2.5. The presence of xylan in the sample was confirmed by nuclear magnetic resonance (?H and ??C) and infrared spectroscopy (IR). Tests were conducted to evaluate the antioxidant potential of XSM. This showed a total antioxidant capacity of 48.45 EAA/g sample. However, did not show scavenging activity of superoxide and hydroxyl radical and also reducing power. But, showing a high capacity chelating iron ions with 70% with about 2 mg/mL. The ability to XSM to influence cell proliferation in culture was also evaluated. This polymer did not influence the proliferation of normal fibroblast cells (3T3), however, decreased the rate of proliferation of tumor cells (HeLa) in a dose-dependent, reaching an inhibition of about 50% with a concentration around 2 mg/mL. Analyzing proteins related to cell death, by immunoblotting, XSM increases the amount of Bax, Bcl-2 decrease, increase cytochrome c and AIF, and reduce pro-caspase-3, indicating the induction of cell death induced apoptosis dependent and independent of caspase. XSM did not show anticoagulant activity in the PT test. However, the test of activated partial thromboplastin time (aPTT), XSM increased clotting time at about 5 times with 600 ?g of sample compared with the negative control. The presence of sulfate on the XSM was discarded by agarose gel electrophoresis and IR. After carboxyl-reduction of XSM the anticoagulant activity decreased dramatically. The data of this study demonstrate that XSM has potential as antioxidant, antiproliferative and anticoagulant compound. Future studies to characterize these activities of XSM will help to increase knowledge about this molecule extracted from corn and allow their use in functional foods, pharmaceuticals and chemical industries. / O sabugo de milho ? um subproduto agr?cola ainda pouco utilizado, isto se deve em parte ao baixo conhecimento do potencial biotecnol?gico de suas biomol?culas. Xilana de sabugo de milho (XSM) ? um polissacar?deo presente em maior quantidade na estrutura do vegetal e seu potencial biotecnol?gico ? pouco conhecido. Este trabalho teve como objetivo a extra??o, caracteriza??o qu?mica e avalia??o de atividades biol?gicas de XSM. Sabugos de milho foram limpos, cortados, desidratados e triturados, dando origem a uma farinha. Esta foi submetida a uma metodologia que combina o uso de meio alcalino com ondas de ultra-som. Ap?s precipita??o metan?lica, centrifuga??o e secagem obteve-se um rendimento de 40% (g/g de farinha). An?lises qu?micas indicaram um alto percentual de polissacar?deos na amostra (60%) e baixa contamina??o por prote?nas (0.4%) e compostos fen?licos (>0.01%). An?lises da composi??o monossacar?dica por cromatografia em papel e por cromatografia l?quida de alta performance (CLAE) indicaram a presen?a de xilose:glicose:arabinose:galactose:manose:?cido glucur?nico em uma propor??o molar de 50:20:15:10:2,5:2,5. A presen?a de xilana na amostra foi confirmada por resson?ncia magn?tica nuclear (13C e 1H) e por espectroscopia de infravermelho (IR). Testes foram realizados para avalia??o do potencial antioxidante de XSM. Esta mostrou uma capacidade antioxidante total de 48.45 EAA/g de amostra. Contudo, a mesma n?o mostrou atividade sequestradora de super?xido, radical hidroxila bem como poder redutor. Em contra partida, apresentou 70% de atividade quelante de ?ons de ferro na concentra??o de 2 mg/mL. A capacidade de XSM em influenciar a prolifera??o celular em cultura tamb?m foi avaliada. Este polissacar?deo n?o influenciou a prolifera??o de c?lulas fibrobl?sticas normais (3T3), entretanto, diminuiu a taxa de prolifera??o de c?lulas tumorais (HeLa) de maneira dose-dependente, chegando a uma inibi??o de aproximadamente 50% com concentra??o em torno de 2 mg/mL. Analisando prote?nas relacionadas ? morte celular, atrav?s de immunoblotting, XSM aumenta a quantidade de Bax, citocromo c e AIF e diminui Bcl-2 e procaspase- 3, indicando a indu??o de morte celular por apoptose dependente e independente de caspase. XSM n?o apresentou atividade anticoagulante pelo teste de PT. Todavia, no teste de tempo de tromboplastina parcial ativada (aPTT), XSM aumentou o tempo de coagula??o em cerca de 5 vezes utilizando 600 ?g de amostra, quando comparadas com o controle negativo. A presen?a de sulfato ligado a XSM foi descartada por eletroforese em gel de agarose e por IR. Ap?s carboxirredu??o de XSM a atividade anticoagulante diminuiu drasticamente. Os dados deste trabalho demonstram que XSM apresenta potencial como composto antioxidante, antiproliferativo e anticoagulante. Estudos futuros de caracteriza??o dessas atividades do XSM contribuir?o para aumentar o conhecimento sobre esta mol?cula extra?da de milho e permitir?o a sua utiliza??o em alimentos funcionais, produtos farmac?uticos e ind?strias qu?micas.

Page generated in 0.0265 seconds