• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 595
  • 586
  • 72
  • 69
  • 30
  • 26
  • 20
  • 17
  • 5
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • Tagged with
  • 1635
  • 529
  • 194
  • 185
  • 185
  • 150
  • 134
  • 133
  • 129
  • 122
  • 122
  • 91
  • 88
  • 86
  • 75
  • 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.
441

Lysyl oxidases:cloning and characterization of the fourth and the fifth human lysyl oxidase isoenzymes, and the consequences of a targeted inactivation of the first described lysyl oxidase isoenzyme in mice

Mäki, J. (Joni) 05 July 2002 (has links)
Abstract Lysyl oxidases (EC 1.4.3.13, protein-lysine 6-oxidases) are extracellular copper enzymes that initiate the cross-linking of collagens and elastin by catalyzing oxidative deamination of the ε-amino group in certain lysine and hydroxylysine residues. The cross-links formed are responsible for the tensile strength of collagen fibers and the unique elastic properties of elastin. Three human lysyl oxidase isoenzymes, lysyl oxidase (LOX), lysyl oxidase-like protein (LOXL), and lysyl oxidase-like 2 protein (LOXL2), have been identified and characterized so far. Two additional human lysyl oxidase isoenzymes, lysyl oxidase-like 3 (LOXL3) and lysyl oxidase-like 4 (LOXL4), proteins were identified, cloned, and partially characterized in this study. Both polypeptides showed a high degree of overall similarity to each other and to the LOXL2 polypeptide, whereas the two polypeptides showed a significant similarity to LOX and LOXL only in the C-terminal region, which contains all amino acid residues thought to be needed for the catalytic activity of the LOX enzyme. The LOXL3 gene is expressed in several tissues, the highest expression levels being in the placenta, heart, ovary, testis, small intestine, and spleen. The LOXL4 gene is likewise expressed in most human tissues studied, the highest levels being seen in the skeletal muscle, testis, and pancreas. Both polypeptides were shown to be secreted extracellular proteins. The role of the first described LOX isoenzyme was studied by inactivating its gene in mice. Most Lox-/- embryos died at the end of gestation, and the few live-born pups were cyanotic and died within a few hours, autopsy revealing large aortic aneurysms. Light microscopy demonstrated structural abnormalities in the aortic walls of Lox-/- embryos, and further analysis by electron microscopy showed highly fragmented elastic fibers, discontinuity in the smooth muscle cell layers, and endothelial cell damage. Doppler ultrasonography of Lox-/- embryos in utero revealed multiple signs of cardiovascular dysfunction, which contributed to the early death of the Lox-/- mice. The results indicate that Lox has an essential role in the development and function of the cardiovascular system and that this role cannot be replaced to any significant extent by other lysyl oxidase isoenzymes.
442

Continuous-flow dynamic dialysis and its application to collagen-ligand interactions

Sparrow, Neil Arthur January 1983 (has links)
Studies undertaken to investigate the binding of low molecular mass analogues of polyphenolic vegetable tannins to collagen have prompted the development of a new method to investigate protein-ligand interactions. This method, the continuous-flow dynamic dialysis method (CFDD), differs from conventional dialysis procedures used for protein-ligand binding studies. In this method, the ligand concentration in the diffusate is monitored automatically at successive closely spaced time intervals while being continuously eluted from the dialysis cell. The primary data obtained by this method consists of a series of spectrophotometric absorbance measurements representing the ligand concentration in the sink compartment of a dialysis cell. This primary data is recorded by means of a data logging device onto a punched paper tape for subsequent computer processing. Two original methods are presented for analysing the primary data to extract the protein-ligand binding isotherm. The first of these is a direct analysis which relies on Fick's first law of diffusion. In this method it is necessary to establish, by means of a control experiment, a value for the ligand permeation constant. This is used in a subsequent analysis to establish a relationship between the measured rate of diffusion of the ligand from a protein-ligand mixture and the concentration of unbound ligand which is in equilibrium with the protein-ligand complex. The protein-ligand binding isotherm is obtained from parametric equations which give the quantity of ligand bound to the protein and the concentration of unbound ligand in the sample compartment as functions of time. The second method, which is more general, utilizes the same primary data but is based on establishing a system transfer function to characterise the dialysis and eluting processes. This analysis depends on the linearity of the system and utilizes numerical laplace transforms of the primary data sets obtained from control and protein-ligand dialyses. Laplace transforms are used to effect a deconvolution of the transfer function from the primary data and yield the concentration of ligand in equilibrium with the protein-ligand complex. This procedure yields, simultaneously, both the total ligand concentration and the concentration of unbound ligand in the protein compartment of the dialysis cell. These quantities are used to establish the binding isotherm for the protein ligand system. Numerical inversion of the laplace transforms in this analysis is effected by their reduction to Fourier series. The experimental reliability of the continuous-flow dynamic dialysis method, and validity of the two analytical methods used to derive a binding isotherm from dialysis data are evaluated from studies of the binding of phenol red to bovine serum albumin (BSA) at 15⁰, 20⁰ and 25⁰ C, as well as from simulated binding curves generated by the numerical solution of the differential equations used to describe the dialysis and elution process in terms of a two-site Scatchard binding model. The method is used to investigate the binding to collagen of a series of low molecular mass phenolic compounds which can be isolated from Wattle and Quebracho vegetable tannin extracts. These compounds can be considered as monomeric precursor analogues of the polymeric vegetable tannins. The binding of these ligands to collagen is shown to be characterised by high capacity, low affinity binding in which the uptake of ligand by the protein increases linearly with increasing ligand concentration. Collagen exhibits no indication of site saturation for these ligands over the experimentally accessible concentration ranges investigated.
443

Optimizing the Approach for Maintaining Single Muscle Fibers in Culture

Hind, Albadrani January 2014 (has links)
The skeletal muscle is a dynamic tissue that has the ability to change and modify itself to fit the level of required activity; a phenomenon called muscle plasticity. Most studies of muscle plasticity are carried out in situ, a condition for which it is difficult to study and discern between the intrinsic properties of skeletal muscle, the myokines released by muscle fibers and the neurotrophic factors released by neurons innervating skeletal muscles that play various roles in the mechanisms of muscle plasticity. Another approach is to study the morphological and contractile properties of single adult muscle fibers under culture conditions for which one can fully control the level of activity and exogenous factors affecting muscle plasticity. However, the survival of single muscle fiber in culture is very low as most fibers degenerated or supercontracted within 5-7 days. The first objective of this study was to optimize fiber survival in culture. The application of chronic stimulation and beta-adrenergic agonists are two major factors that prevent muscle atrophy and loss of force in denervated muscles in situ. So, objective two was to determine if chronically stimulated single fibers in culture also improve fiber survival and contractile characteristic under culture conditions. The third objective was the same for salbutamol, a beta 2-adrenergic agonist. In regard to the optimization of fiber survival, the Minimum Essential Medium (MEM) was a better medium than Dulbecco’s Modified Eagle Medium (DMEM), changing 50% of the culture medium every two days also improved fiber survival compared to changing the medium every day. Interestingly, inhibiting the proliferation of satellite cells with AraC largely improved fiber survival when fibers were kept under resting conditions, but not when they were chronically stimulated. Finally, under conditions in which proliferation of satellite cells was inhibited, the use of a collagen/laminin mixture as adhering substrate to improve fiber adhesion to glass coverslip gave rise to a better fiber survival than Matrigel that contains not only collagen and laminin but several growth factors. The results suggest i) that when satellite cells (or fibroblasts) are allowed to proliferate they appear to contribute to the degeneration of fibers under resting conditions and ii) that the release of myokines by skeletal muscle fibers (or cytokines by other cells) likely play a role in fiber survival. Contrary to the situation in situ, neither the chronic stimulation nor salbutamol improved fiber survival and contractile characteristics of muscle fibers in culture suggesting that some important factors in culture are missing to allow chronic stimulation and salbutamol to reduce muscle atrophy and loss of force.
444

From molecules to tissues : characterising the relationship between structure and function in ageing arteries

Walton, Lucy Anne January 2015 (has links)
Increased arterial stiffness is a predictor of cardiovascular events and mortality across a diverse range of populations. Although gross-mechanical stiffness can be measured in vivo, in order to understand the pathological mechanisms it will be necessary to identify which local micro-structural remodelling events are the prime drivers of altered macro-mechanical function. However, characterisation of arterial structure by conventional histological approaches: i) commonly induces artefacts as a consequence of the sectioning process, ii) provides no insight into the three dimensional structure of the tissue and iii) is performed on unpressurised tissue. This project has set out to address these limitations by developing new micro computed x-ray tomography (micro-CT) methodologies which are capable of visualising the three dimensional structure of rat arteries. This new methodology was then been applied in combination with gross-and micro-mechanical testing and atomic force microscopy imaging to characterise the effects of both intra-luminal pressure and age on arterial structure and function. From these investigations it was clear that micro-CT could readily distinguish discrete tissue sub-structures in paraffin embedded tissues, including skin and arteries and that this imaging approach was compatible with complimentary histological and immunohistochemical analyses. Characterisation of the structure and mechanical function of carotid arteries in aged rats demonstrated localised stiffening in the adventitial layer and a change in the molecular structure of adventitial collagen. The effects of intra-luminal pressure on structure using micro-CT revealed changes in artery cross-sectional area, which suggest the artery wall may be compressible. Investigations into the effects of pressure on the molecular structure of adventitial collagen revealed an increase in periodicity at mean pressure. These findings together demonstrate that the adventitial layer has an important role in the development of arterial stiffness. Micro-CT can reveal novel information that improves our understating of artery structure and how artery structure changes during ageing.
445

Estudo da organização do colágeno e resistência do ligamento periodontal em incisivos de ratos irradiados / Study of collagen organization and strength of the periodontal ligament in rat incisors irradiated

Silva, Karla Rovaris da, 1987- 03 January 2013 (has links)
Orientador: Pedro Duarte Novaes / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-22T06:39:35Z (GMT). No. of bitstreams: 1 Silva_KarlaRovarisda_M.pdf: 5383756 bytes, checksum: f46eb2dfd48068a21c19841f2e4d3581 (MD5) Previous issue date: 2013 / Resumo: Os efeitos adversos da radioterapia sobre os tecidos orais vêm sendo estudados com intuito de, cada vez mais, entender como esta age sobre o organismo, bem como para o desenvolvimento de métodos ou substâncias que visem à minimização dessas sequelas. Dentre os tecidos que estão na área de exposição, está o ligamento periodontal, que se afetado, pode ocasionar a perna dentária que impreterivelmente interfere na qualidade de vida do indivíduo. Este trabalho teve como objetivo avaliar o efeito da radiação ionizante sobre o ligamento periodontal do dente incisivo de rato albinus wistar, por meio da microscopia de polarização e do teste de força. A amostra constituiu-se de 30 ratos albinus wistar machos divididos em dois grupos, o grupo controle (15) e o grupo irradiado (15). O grupo irradiado foi submetido à sessão única de radioterapia com dose de 15Gy e após 14 dias todos os animais foram sacrificados. Um animal de cada grupo foi perdido durante a execução do trabalho. Desta forma, sete animais de cada grupo foram submetidos ao teste de resistência do ligamento periodontal e os sete restantes tiveram a organização do colágeno avaliada através da microscopia de polarização. Os resultados mostraram que ambos os testes apresentaram diferença estatisticamente significante entre os grupos (p<0,001). Através dos coeficientes de correlação de Pearson encontrou-se também uma forte correlação entre os resultados dos testes (resistência/polarização) de cada grupo (controle/irradiado) (R = 0,683; p < 0,001). Portanto, concluiu-se que a radioterapia pode levar à diminuição da resistência à força de intrusão e provocou a desorganização do colágeno no ligamento periodontal / Abstract: The adverse effects of radiotherapy on oral tissues have been studied in order to increasingly understand how it works on the body, as well as for the development of methods and substances aimed at minimizing these sequelae. Among the tissues that are in the exposition area, is the periodontal ligament which, when affected, can lead to tooth loss, that unfailingly interferes with quality of life. This study had as purpose to evaluate the effect of ionizing radiation over the periodontal ligament of the incisive tooth of the albinus wistar rat, trough the polarizing microscope and the strength test. The sample was composed of 30 albinus wistar male rats, separated into two groups, the control group (15) and the irradiated one (15). The irradiated group was subjected to an only session of radiotherapy, with a 15Gy dose, and after 14 days all the animals were sacrificed. One animal in each group was lost during the study's execution. Hence, seven animals of each group were subjected to the periodontal's ligament resistance test, and the seven remaining had their collagen organization evaluated trough the polarizing microscopy. The results showed that both tests exhibited statistically significance difference between the groups (p<0,001). Using the Pearson correlation coefficients a strong correlation was also found between the tests results (resistance/polarizing) of each group (control/irradiated) (R = 0,683; p<0,0001). Thereby, the conclusion was that radiotherapy can lead to a diminished resistance to the intrusion strength and to a disorganization of the periodontal's ligament collagen / Mestrado / Radiologia Odontologica / Mestra em Radiologia Odontológica
446

Imobilização de colágeno em arcabouços de poli (L-co-D,L ácido lático) / Collagen imobilization on poly (L-co-D,L lactic acid)

Más, Bruna Antunes, 1986- 18 August 2018 (has links)
Orientador: Eliana Aparecida de Rezende Duek / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-18T15:18:31Z (GMT). No. of bitstreams: 1 Mas_BrunaAntunes_M.pdf: 4024365 bytes, checksum: 4922b258d265a9070576f02830e45d40 (MD5) Previous issue date: 2011 / Resumo: Polímeros biorreabsorvíveis são amplamente empregados como arcabouços na engenharia tecidual. No entanto, devido à natureza hidrofóbica, técnicas de modificação de superfície embasadas na enxertia de grupos químicos funcionais e imobilização de moléculas bioativas são desenvolvidas no intuito de promover a biofuncionalização da superfície desses polímeros, ocasionando uma melhora significativa da interação célula /polímero. Este estudo teve por objetivo desenvolver e caracterizar uma superfície biomimética em arcabouços do copolímero poli (L-co-D,L ácido lático)- PLDLA, através da enxertia de grupos (-COOH) e imobilização de colágeno tipo I. Os arcabouços de PLDLA 70/30 foram obtidos pela técnica de lixiviação de porógenos e submetidos ao método de fotopolimerização oxidativa da superfície do material, seguido da copolimerização enxertiva do ácido acrílico (PLDLA-AAc) e imobilização do colágeno tipo I (PLDLA-Col). A superfície das amostras foi caracterizada por Microscopia Eletrônica de Varredura (MEV), Microscopia de Força Atômica (MFA), Espectroscopia de Reflectância Total Atenuada (FTIR-ATR), Espectroscopia de Fotoelétrons Excitados por raios-X (XPS) e ângulo de contato. As imagens da MFA e fotomicrografias da MEV demonstraram a formação de poros e rugosidade na superfície dos arcabouços de PLDLA-AAc e, deposição do colágeno com formação de uma estrutura fibrilar em pontos inespecíficos da superfície dos arcabouços do PLDLA-Col, resultando no aumento da rugosidade superficial de 149.5nm (PLDLA puro) para 295nm (PLDLA-Col). Os espectros de FTIR-ATR do PLDLA, PLDLA-AAc e PLDLA-Col confirmaram a presença dos mesmos picos de absorção para todos os tratamentos e, a presença dos picos em 1662 e 1559cm-1, típicos de amida I e II nas amostras de PLDLA-Col. A citocompatibilidade dos arcabouços foi avaliada através do cultivo de células osteoblásticas primárias submetidas aos ensaios de citotoxicidade e adesão celular inicial, síntese de colágeno e observação da morfologia celular, obtidas pela MEV. Os resultados obtidos mostraram que a superfície biomimética dos arcabouços de PLDLA-Col melhora, significantemente, a taxa de adesão e proliferação celular bem como estimula a síntese de colágeno (p<0,01). Estes resultados são indicativos de que o método de modificação de superfície utilizado no presente estudo pode ser usado no desenvolvimento de arcabouços bioativos e biomiméticos com potencial aplicação na engenharia tecidual / Abstract: Bioreabsorbable polymers are widely used as scaffolds in tissue engineering. However, due to their hydrophobic nature, modification techniques based on graft of chemical functional groups and immobilization of bioactive molecules have been developed, in order to promote biofuncionalization of material surface, causing better interaction between cell / polymer. This study aimed at developing and characterizing a biomimetic surface on scaffolds of the copolymer poly (L-co-D, L lactic acid) (PLDLA 70/30), by grafting of chemical functional groups and immobilized with collagen type I. The scaffolds were obtained by porogen leaching, and submitted to photo-oxidation method of the material surface followed by grafting polymer polymerization of the acrylic acid solution (PLDLA-Acc) and immobilization of the type I collagen (PLDLA-Col). The sample surfaces were characterized by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) , Attenuated Total Reflectance Infrared Spectroscopy (ATR-FTIR), X-ray Photoelectron Spectroscopy (XPS) and contact angle. AFM images and SEM electromicrographs exhibited porous formation and roughness on the PLDLA-AAc surfaces and collagen deposition with net-like fibrillar structure in non-specific areas of the PLDLA-Col scaffolds, resulting an increase in surface roughness from 149.5 nm (PLDLA pure) to 295nm (PLDLA-Col). ATR-FTIR spectra of PLDLA, PLDLA-AAc and PLDLA-Col exhibited the same absorption peaks for all samples, as well as peaks of 1662 and 1559cm-1 , typical of amide I and II in PLDLA-Col samples. Scaffolds cytocompatibilty was evaluated by osteoblastic-like cell culture, submitted to cytotoxicity and initial cell adhesion assays, collagen synthesis and observation of cell morphology obtained by SEM. The result showed that biomimetic surface of PLDLA-Col scaffolds significantly improves adhesion and cell proliferation rates, as well as stimulates collagen synthesis (p<0,01). These results indicate that the surface modification method in the present study can be used in the development of bioactive and biomimetic scaffold with potential application in tissue engineering / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica
447

Efeito da remoção do colageno na resistencia ao cisalhamento de dois sistemas adesivos de frasco unico

Saboia, Vicente de Paulo Aragão 23 July 1998 (has links)
Orientador: Luiz Andre Freire Pimenta / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-07-24T01:11:58Z (GMT). No. of bitstreams: 1 Saboia_VicentedePauloAragao_M.pdf: 3642627 bytes, checksum: 3810c206c50b67463e5e76e570894df6 (MD5) Previous issue date: 1998 / Resumo: O objetivo deste trabalho foi verificar os efeitos remoção do colágeno na resistência ao cisalhamento de dois sistemas adesivos de frasco único e examinar a micromorfologia da dentina, antes e após o teste de cisalhamento, em lupa estereoscópica e MEV. Foi usado como substrato dentina planificada de terceiros molares recém-extraídos e armazenados em formal a 10% (pH neutro). Foram usados os adesivos Prime & Bond 2.1 (PB-Dentsply) e Single Bond (SB-3M). Nos grupos controle (1 e 3), após aplicação da ácido fosfórico a 37%, os adesivos foram aplicados de acordo com as instruções do fabricante, enquanto que nos grupos experimentais (2 e 4), após o condicionamento ácido, foi aplicada uma solução de hipoclorito de sódio a 10% (H), por 1 minuto, para remover o colágeno exposto pelo condicionamento ácido. Foram cqnfeccionados cilindros de 3 mm de diâmetro por 5 mm de altura com resina composta Z-100 (3M). Após 24 horas em ambiente úmido a 37 °e, foi realizado o teste mecânico de cisalhamento com velocidade de 0,5 mm/min. Os resultados explorátórios e do Teste de Kruskal-Wallis podem ser observados na tabela abaixo. ... Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital / Abstract: The purpose of this study was to evaluate the effect of removing collagen using Single Bond-3M (SB) according to the manufacturer's to four groups and on the shear bond strength for two single-bottle adhesives systems and to examine the dentin surfaces after shear test. The buccal and lingual surfaces of 80 extracted human third molars were ground to expose dentin, then polished with 320, 400 and 600-grit aluminum oxide. Teeth were randomly assigned received the following treatments: group 1, samples were conditioned with 37% phosphoric acid , rinsed and left moist, Prime & Bond 2.1-Dentsply (PB) adhesive was applied according to manufacturer's directions, and restorative Z100 (3M) composite resin was bonded to the dentin surface; group 2, the same procedures were followed as for group 1 except the surfaces were treated with 10% NaOCI for 1 minute, after acid conditioning; group 3, the same technique was followed as for group 1 , recommendations; group 4, the same procedure was followed for group 2, using Single Bond. The specimens were stored. in humidity at 37°C for 24 hours and tested in a shear mode at a crosshead speed of 0,5 mm/minute. The median of results were: G2=21,84, G3=15,99, G1=15,02 and G4=13,82. The Kruskal-Wallis test and multiple comparisons were used for statistical analysis of the data. A 1 minute exposure of dentin to 10% NaOCI following acid conditioning resulted in significant increase on the dentin shear bond strength for Prime & Bond 2.1 (group 2). The same treatment for Single Bond (group 4) resulted in significant reduction on the values of adhesion. Groups 1 and 3 were not statistically different from each other. Group 2 showed more dentin-cohesive failures than the other groups. Under SEM observations, there were morphological differences between the groups treated with NaOCI and those that did not received this treatment / Mestrado / Dentística / Mestre em Clínica Odontológica
448

A busca de mediadores para a modulação de colágeno: efeito de moléculas ativas incorporadas a biomaterial polérico

Ingracio, Anderson Ricardo 03 July 2018 (has links)
No description available.
449

Aplicação da biofotônica para o estudo de cicatrizes / Application of biophotonics to the study of scar tissue

Ferro, Daniela Peixoto, 1981- 26 August 2018 (has links)
Orientador: Konradin Metze / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-26T20:44:11Z (GMT). No. of bitstreams: 1 Ferro_DanielaPeixoto_D.pdf: 2964245 bytes, checksum: 202d309cf65f632d47c7811d4958535d (MD5) Previous issue date: 2015 / Resumo: A aplicação integrada de técnicas modernas, como a Geração do Segundo Harmônico (SHG) e os tempos de vida da fluorescência (FLIM), com análise de imagens matemáticas nos permitem visualizar detalhes não vistos por microscopia de luz convencional. O objetivo deste estudo foi investigar se isto também pode ser aplicado para a investigação de tecido cicatricial. Foram estudados 28 casos de preparações histológicas de rotina, de quelóides, cicatrizes hipertróficas e normais. A Fluorescência de dois fótons e SHG foram obtidas por um microscópio multifóton (LSM 780 NLO-Zeiss), em objetiva de 40X e excitados por um laser Mai Tai de Ti: Safira (comprimento de onda de 940 nm). Foram adquiridas imagens em 3D e foram criadas imagens justapostas a fim de comparar diferentes cicatrizes ou várias regiões no interior da mesma cicatriz com análise de imagens informatizadas. Variáveis de Textura derivadas a partir da matriz de coocorrência das imagens de fluorescência mostraram diferenças significativas entre as cicatrizes normais, cicatrizes hipertróficas e quelóides. Para a análise do FLIM, foi utilizado um sistema composto por um microscópio confocal (LSM780-NLO- Zeiss), com objetiva de 40x e um sistema FLIM acoplado. As amostras foram excitadas por um laser de diodo a 405nm. Estudamos secções não coradas de 32 casos processados rotineiramente de tecido cicatricial incluídos em parafina. As áreas das regiões centrais e periféricas foram selecionadas aleatoriamente e comparadas. Os tempos de vida de fluorescência das hemácias serviram como padrão interno. Os tempos de vida do colágeno em áreas centrais em todos os tipos de cicatrizes foram significativamente mais longo do que em áreas periféricas. Houve correlação positiva entre os tempos de vida de fluorescência das hemácias e as fibras de colágeno entre os casos. Em resumo, o SHG e a técnica Flim revelam em cicatrizes rotineiramente processadas, características morfológicas dos tecidos, que não podem ser detectadas por microscopia de luz convencional / Abstract: The integrated application of modern techniques such as Second Harmonic Generation (SHG) and fluorescence lifetime imaging (FLIM) with mathematical image analysis enable us to visualize details not seen by conventional light microscopy. The aim of this study was to investigate whether this could also be true for the investigation of scar tissue. 28 routine histological preparations of keloids, hypertrophic and normal scars were studied. Two-photon fluorescence and SHG was obtained by a multiphoton microscope (LSM 780 NLO-Zeiss (at 40X objective magnification) and a Mai Tai Ti: Sapphire laser with excitation at 940 nm wavelength. 3D reconstructed patchwork images were created in order to compare different scars or various regions inside the same scar with computerized image analysis. Texture variables derived from the co- occurrence matrix of the fluorescence images showed significant differences between normal scars, hypertrophic scars and keloids. For FLIM analysis we used a system composed of a confocal microscope Zeiss LSM780 Upright-NLO with the 40x objective and a FLIM detection system. The samples were excited by a laser diode at 405nm. We studied unstained sections of 32 routinely processed and paraffin-embedded cases of scar tissue. Randomly selected areas of the central and peripheral regions were compared. The fluorescence lifetimes of red blood cells served as internal standard. Lifetimes of collagen in central areas of all scar types were significantly longer than in the periphery. There was a significant positive correlation between the fluorescence lifetimes of red blood cells and collagen fibers among the cases. In summary, SHG and FLIM techniques reveal in routinely processed scar tissue morphological characteristics, which cannot be detected by conventional light microscopy / Doutorado / Biologia Estrutural, Celular, Molecular e do Desenvolvimento / Doutora em Fisiopatologia Médica
450

Quitosana, Colágeno, Mangostão: preparo e caracterização de scaffolds e géis / Chitosan, Collagen, Mangosteen: obtainment and characterization of scaffolds and gels

Eduardo Pedro Milan 26 July 2017 (has links)
A quitina é um biopolímero abundante na natureza e seu derivado, a quitosana é tido como excelente biomaterial na engenharia tecidual por sua versatilidade e propriedades, assim como colágeno que por sua presença natural no organismo e seu papel biológico fazem com que seja amplamente utilizado na medicina. As blendas destes biopolímeros possuem excelentes propriedades mecânicas devido às interações eletrostáticas e pontes de hidrogênio, e propriedades biológicas pelos materiais que as compõe, já demonstrando eficácia na regeneração tecidual. O extrato de Garcinia mangostna L., ou extrato de mangostão, é pouco estudado no ocidente, mas no oriente é amplamente utilizado para fins medicinais, com propriedades promissoras na área de engenharia tecidual. A interação deste com as blendas de quitosana/colágeno ainda não foram estudadas. Este trabalho teve como objetivo a obtenção e estudo de scaffolds de quitosana/colágeno em diferentes proporções (1:1, 2:1 e 3:1) com extrato de mangostão em variadas concentrações (10, 20 e 30%). A quitosana foi extraída por desacetilação da &#946-quitina de gládios de lula, o colágeno aniônico foi obtido de tendão bovino por hidrólise alcalina e o extrato de mangostão foi obtido da casca do fruto. A caracterização da quitosana e assim como colágeno, extrato e misturas foram analisados por absorção na região do infravermelho (FT-IR), efetuou-se um ensaio reológico dos géis e os scaffolds foram submetidos à calorimetria exploratória diferencial (DSC), microscopia eletrônica de varredura (MEV), ensaios de intumescimento e liberação do extrato. Ensaios reológicos indicam um comportamento pseudoplástico para todas as amostras e se feito um tratamento matemático, o melhor modelo às quais estas se adaptam seria o modelo de Carreau. Os DSC dos scaffolds mostram que a adição de extrato tende à elevar a temperatura de desnaturação (Td) do colágeno. Espectros FT-IR caracterizaram o extrato e não mostraram resultados conclusivos sobre a incorporação dele aos filmes. Fotomicrografias por MEV mostram alteração no tamanho médio de poros e canais com a adição de extrato. Ensaios de intumescimento dos scaffolds mostram uma diminuição de capacidade de absorção com adição de extrato, os ensaios de liberação feitos para os scaffolds das misturas mostram uma liberação entre 25-35% do extrato sendo as cinéticas de liberação modeladas pelo modelo de Kosmeyer-Peppas para a maioria das amostras. Obtendo-se assim géis e scaffolds que mostram resultados inicias promissores e com acréscimo de estudos complementares podem vir a ser utilizados no campo da engenharia tecidual. / Chitosan is an abundant biopolymer in nature, and it is an excellent biomaterial for tissue engineering due to its versatility and properties. Collagen, by the natural presence in the organism and to the biological role makes it widely used in medicine. These biopolymers blends have excellent mechanical properties due to electrostatic interactions and hydrogen bonds, and biological properties, demonstrating good efficiency in tissue engineering. The Garcinia mangostana L. extract, or mangosteen extract, is not very well studied in the western culture, but in the eastern, it is widely used in local medicine, with promising properties in tissue engineering field. The interaction between chitosan/collagen blends and mangosteen extract has not yet been studied. This study aims to obtain scaffolds from chitosan/collagen blends in different ratios, such as 1:1, 2:1 and 3:1 with different extract concentrations (10, 20 and 30%). Chitosan was obtained by deproteinization and deacetylation of &#946-chitin from squid\'s pens, anionic collagen was obtained from bovine tendon by alkaline hydrolysis, and the mangosteen extract was obtained from the hulls of fruits. Materials characterization was done by FT-IR, DSC, SEM, swelling and extract release in buffer solution. Rheological measurements were made with the gels formed from the mixture of the components. The rheological studies indicates a pseudo plastic behavior to all samples and by a mathematical treatment, the Carreau mathematical model was the best fitting. The DSC analysis for the collagen mixtures indicated a tendency to elevate the denaturation temperature with addition of extract. With the FT-IR results, we could obtain mangosteen extract spectrum but the mixtures spectrum did not show the extract incorporation. The photomicrographies obtained by SEM showed pore and channels alteration with extract addition. Swelling studies showed a decrease in swelling capacity after extract addition, release studies showed a 25-35% extract release by scaffolds and in most cases the kinetic was fitted by Kosmeyer-Peppas. Thus obtaining promising gels and scaffolds in the field of tissue engineering, but needing of further development.

Page generated in 0.0578 seconds