Tesi sul tema "College Corner"
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Musselmann, Kurt. "Developing culture conditions to study keratocyte phenotypes in vitro". [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001726.
Testo completoEtheredge, LaTia Shaquan. "The Effect of Growth Factors on the Corneal Stroma Extracellular Matrix Production by Keratocytes". [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0003238.
Testo completoVrana, Nihal Engin. "Collagen-based Scaffolds For Cornea Tissue Engineering". Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/3/12607540/index.pdf.
Testo completohowever, the presence of cells increased the tensile strength of the films over a 21 day period to close to that of the native cornea and compensated for the loss of strength due to degradation. The micropatterned films proved to have higher transparency than the unpatterned scaffolds. In this study, it was possible to prepare collagen based micropatterned scaffolds using a silicon wafer and then a silicone template, successively, starting from original designs. The resultant collagen films were able to control cell growth through contact guidance, restricted cells and secreted-ECM within the pattern grooves, resulting in a higher transparency in comparison to unpatterned films. Thus, the tissue engineered constructs revealed a significant potential for use as total artificial corneal substitutes.
Ibrahim, Jamal. "Hydroxylysine glycosides of corneal collagen". Thesis, University of Oxford, 1986. http://ora.ox.ac.uk/objects/uuid:2442f75c-6a1c-4575-98b0-a4475a3df1f2.
Testo completoSong, Yihui. "Development of a printable collagen bioink for treatment of corneal disease". Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/27218.
Testo completoAcun, Aylin. "Construction Of A Collagen-based, Split Thickness Cornea Substitute". Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615340/index.pdf.
Testo completom) multilayer tissue which performes around 75% of the total refraction in the eye. It also protects the inner layers against any type of damage. Since it is avascular, the three cellular layers of cornea always need transport of nutrients and other materials in and out of the tissue via diffusion. Any change in shape, transparency or thickness of cornea, or physical damages and infections, may cause serious defects. The conventional methods are satisfactory in the treatment of mild injuries but severe cases require the substitution of the tissue with an equivalent. Keratoprosthesis and donor corneas that are used as replacements do not completely meet requirements. Tissue engineering can be an alternative method for preparing a biocompatible and stable cornea equivalent. The ability to choose from a variety of materials and the ability to incorporate bioactive agents allow the researchers to tailor make the construct. The structure needs to be seeded with the patient&rsquo
s own cells and cultured in vitro to yield an optimal corneal replacement. In this study a novel, split thickness cornea replacement is proposed to substitute the two upper cellular layers (epithelium and stroma) of the native cornea. The design includes a chondroitin sulfate impregnated collagen type I (isolated from rat tail) foam (CSXLF) produced by lyophilization carrying electrospun fibers of the same polymer collected directly on top of the foam, forming the bilayer structure (Fo-Fi). The fiber layer was intended to separate the epithelium and the stroma of the reconstructed cornea yet to allow material transfer in between. The foam layer (bottom) was crosslinked by N-ethyl-N-[3-dimethylaminopropyl] carbodiimide (EDC), and N-hydroxy succinimide and after fiber deposition the bilayer was further stabilized with physical crosslinking (DHT method). The physical characterization of the foam showed that their pore sizes (10-200 µ
m) and porosities (around 70%) were well within the desired range for typical tissue engineering applications. The cell free wet thicknesses of both single and bilayer constructs were close to that of the native stroma and light transmittance through these scaffolds was quite high (around 82% in the 500-700 nm range). The scaffolds were also tested for their stability and shown to be suitable for in vitro testing. In vitro studies were performed using retinal pigment epithelial cells (RPE, D407 cell line) and isolated human corneal keratocytes (HK) to reconstruct the epithelium and the stroma, respectively. Three types of constructs were prepared
only HK seeded Fo-Fi constructs, RPE-HK seeded CSXLFs, and RPE-HK seeded Fo-Fi constructs. All were shown to support cell attachment and promoted cell proliferation as was shown by the cells that covered the inner and outer spaces of the scaffolds. The fiber layer prevented the mixing of the two cell types, without hindering material exchange between them. Moreover, when co-cultured for 14 days, the keratocytes started to deposit collagen type I, a specific marker of these cells. In contrast, ECM deposition could not be observed in the single type cell seeded samples. The co-cultured bilayer construct was tested for suturability at the end of 31 days of in vitro incubation and it was shown that it could be successfully sutured without any major tears. Under the light of these results it was concluded that both the single layer and the bilayer constructs show promise for use as split thickness cornea replacements.
Giacomin, Natalia Torres. "Análise da eficácia e segurança do crosslinking corneano em pacientes com ceratocone avançado". Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/5/5149/tde-09042018-100655/.
Testo completoPURPOSE: To analyze the safety and efficacy of standard corneal collagen crosslinking (CXL) in advanced cases of progressive keratoconus (KC) after four years of follow-up. METHODS: A retrospective case series of patients with advanced progressive KC (stage 3 and 4 of Amsler-Krumeich classification) underwent standard CXL treatment. The parameters examined were changes in uncorrected visual acuity (UDVA), corrected visual acuity (CDVA), keratometry values (mean K, flattest K, steepest K, and apical K), pachymetry, and endothelial cell count at the baseline and at 12-, 24- and 48-months postoperatively. RESULTS: Forty eyes of 40 patients were enrolled into the study. The mean patient age was 22.5 years (range: 15 to 37 years). Both mean UCVA and CDVA remained stable during the time points; no statistically significant change was noted. Although a slightly reduction was observed in all keratometric readings, a statistically significant reduction was only reached in the apical K (p=0.037) at four years after CXL. A significant reduction in the pachymetry was also found (from 388±49 to 379±48 um, P < 0,0001 and from 362±48 to 353±51 um, P < 0,0001, ultrasonic and slit-scanning readings, respectively) ; however this change is not likely clinically meaningful. Endothelial cell count was not significantly modified at the end of the study. Treatment failure or progression was noted in two patients (5%) over the followup period. CONCLUSION: Standard CXL treatment seems to be safe and able to stabilize both visual acuity and topographic parameters at four-year follow-up in advanced keratoconic eyes
Ghannad, Mona. "Design and Synthesis of Collagen-binding Anti-microbial Proteins". Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19981.
Testo completoLappin, Cory James. "Investigating the Role of Shroom3 in Collagen Regulation and Development of the Corneal Stroma". The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1523921114811659.
Testo completoHemmavanh, Chinda. "Regulatory Roles of FACIT Collagens XII and XIV in Cornea Stromal and Endothelial Development and Function". Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5038.
Testo completoRajendran, Vijayalakshmi. "Role of mesenchymal stem cells and collagen-based corneal equivalents in restoring corneal graft transparency". Thesis, University of Aberdeen, 2016. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=232053.
Testo completoCARLSON, ERIC CURTIS. "THE ROLE OF LUMICAN IN THE FORMATION OF BIO-GLASS: TRANSPARENT CORNEA". University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1044293658.
Testo completoZILLIOX, PATRICIA. "Le chlorure de benzalkonium, agent antimicrobien en ophtalmologie : influence de la longueur de la chaine carbonee sur son efficacite antimicrobienne et sur la toxicite corneenne". Strasbourg 1, 1988. http://www.theses.fr/1988STR15078.
Testo completoGAUTHIER, LAURENT. "Utilisation d'une colle de fibrine (tissucol) pour traiter les ulceres de cornee perfores et preperfores". Bordeaux 2, 1988. http://www.theses.fr/1988BOR23003.
Testo completoKilic, Cemile. "Study Of Patterned, Multilayered, Collagen-based Scaffolds Designed To Serve As A Cornea Stroma". Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615389/index.pdf.
Testo completom in thick. It protects the eye from external objects and it is the main optical element of the eye refracting 70 % of the incoming light. After cataract, corneal diseases and wounds are the second leading cause of the blindness that affects more than 4 million people worldwide. For the highly damaged corneas where the corrections with spectacles or contact lenses cannot be achieved, tissue replacement is the only choice, and is done by cornea transplantation or keratoprostheses. However, due to limited number of donor corneas and the risk of infections during transplantation, and development of glaucoma, necrosis and other complications caused by the keratoprostheses, prevent them from meeting expectations. Tissue engineering is a promising field which emerged from biomaterials science and aims to replace, restore or improve the function of the diseased or injured tissues. In this method, after the production of an ideal scaffold that mimics the natural human tissue, cells of the host are isolated, increased in number, and seeded on the scaffold developed to serve as the microenvironment of the cells. In the current study a 3D corneal stroma replacement was designed to mimic the native stroma. It consisted of 4 films of patterned collagen or collagen blended with Elastin Like Recombinamer (ELR) stacked on top of each other and then crosslinked by dehydrothermal (DHT) treatment. The characterization of the films showed that the pattern fidelity was good and they did not deteriorate after crosslinking. Enzymatic and in situ degradation studies showed that the DHT treatment at 150 oC for 24 h (DHT150) was the optimum condition. The transparency of all the films was quite high where uncrosslinked (UXL) films and DHT150 Col:ELR films yielded the best results. The individual films and 3D construct of 4 stacked films were seeded with isolated human corneal keratocytes (HK) and cultured for 21 days. Cells attached and proliferated well on the single Col and Col:ELR films. However, the proliferation was higher on Col multilayer constructs than their Col:ELR counterparts. Cells were aligned along the patterns of the films while no significant alignment was observed for the cells on unpatterned films. Ultimate tensile strength (UTS) and Young&rsquo
s Modulus (E) of Col and Col:ELR films were significantly lower after a 30 day culture than that of unseeded films of Day 1. Transparency of the seeded Col:ELR films was superior to Col films over a 30 days test and quite close to the transmittance of the native human cornea. It was concluded that the Col and Col:ELR patterned films and their 3D constructs have a significant potential for use as a corneal stroma equivalent.
Harper, Heather. "Solvent Dependent Molecular Mechanics: A Case Study Using Type I Collagen". Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5035.
Testo completoHadley, Julia C. "Glycation of Type I collagen in ocular tissues and tendon". Thesis, Open University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286926.
Testo completoBeshtawi, Ithar. "The structural and functional effects of corneal collagen cross-linking on human corneal tissue". Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/the-structural-and-functional-effects-of-corneal-collagen-crosslinking-on-human-corneal-tissue(12f210fe-82b6-4855-a3ea-c5abd828642d).html.
Testo completoParfitt, Geraint. "Proteoglycans as dynamic regulators of the organised collagen fibril architecture in the cornea : an electron tomography study of the mouse corneal stroma". Thesis, Cardiff University, 2011. http://orca.cf.ac.uk/55104/.
Testo completoTouboul, David. "Apport de l’élastographie par imagerie des ondes de cisaillement pour l’évaluation de la photo-polymerisation du collagène cornéen". Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0051/document.
Testo completoCorneal collagen cross-linking (CXL) is a kind of minimaly invasive corneoplasty mainlybased on a biomechanical concept, which is very difficult to measure physically, and whichthe therapeutic efficacy understanding is complex.Principles, different protocols and resultsare summarized in this thesis in order to illustrate the usefulness of the experimental modelchosen in our experimentations about elastographic corneal shear wave imaging.The pathway of our experimental work have led to the choice of trans-epithelial CXL (TCXL)assisted by iontophoresis (I-CXL), performed in vivo, on rabbits eyes. Elastographicmeasurements we obtained after animals euthanasia have shown a significant change of thecorneal elasticity profile after CXL, successively tested in a dynamic and in a static fashion.Our results do confirm the biomechanical efficacy of the I-CXL procedure and give a moreprecise idea of the sole photo-polymerization effect by avoiding any confounding healingconcern. Technological issues for corneal elastography with shear wave imaging have beenraised in this thesis to develop a realistic strategy for the launch of a clinically useful device
Tidu, Aurélien. "Synthèse d'une cornée artificielle à base de collagène I". Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066472/document.
Testo completoIn view to generate artificial corneas, dense transparent collagen type-I scaffolds were synthesized exploiting the intrinsic liquid crystals properties of collagen molecules. 3 mg/mL collagen solutions in 500 mM acetic acid were dialyzed against a solution of precise concentrations in acetic and hydrochloric acid. When concentrated, solution provided a liquid-crystal organization resembling plywood, which is the organization of the collagen fibrils in the cornea. This was verified by polarized light and second harmonic generation microscopy experiments. In parallel these collagen solutions were also concentrated by centrifugation-filtration up to 90 mg/mL. The concentrated solutions were pressed into cornea-like shape and submitted to ammonia vapor in order to induce the fibrillogenesis of collagen. The result is a transparent dense fibrillated collagen matrix (transparency 90 %). Transmission electron microscopy revealed that fibrils kept the organization of the concentrated solution. Using a custom made device, mechanical tests showed that the Young modulus reached 900kPa. Human donor limbal explants were sewed on top of the scaffolds and cultured for 14 days. Optical microscopy and immunocytochemical analysis showed the development of an epithelium with characteristics of corneal epithelial cells. Preliminary experiments showed that keratocytes could be successfully inserted during the synthesis process. Thus, the results show the viability of the process of fabrication, and the following step is the in vivo experiment
Ivanova, Ivelina. "Comportement mécanique de console courte en béton armé renforcée ou réparée par collage des matériaux composites". Thesis, Reims, 2013. http://www.theses.fr/2013REIMS033/document.
Testo completoThis study deals with mechanical behaviour of strengthening reinforced concrete corbel by bonding carbon fibre sheet and in particular the influence of the number of layers of carbon fiber fabric, the type of strengthening, the orientation of the composite fabric and the type of carbon fiber fabrics .The results show that the performance of the corbel does not increase linearly with the thickness of the composite plate. There is an optimum thickness of the carbon fiber fabrics. In the case of strengthening on both sides of the concrete, there are an optimum number of layers. In the case of fully wrapped strengthening, the most interesting thickness of the composite is three layers. However, the resistance of the strengthening reinforced concrete corbel depends strongly on the bonded surface.The results also show that the behavior of strengthening corbel can be presented in three phases: the overall elastic phase, the phase of crack propagation and the phase of the opening of diagonal cracks. Strengthening the corbel can significantly increase the ultimate strength from 20% to 82 % and the stiffness of the corbel. The failure of the strengthening corbel can be summarized in five modes.Based on the results obtained and the existing models, the ultimate strength of the strengthening corbel or without strengthening, was estimated and analyzed. A model based on damage theory has been developed in this work. The effect of fatigue on the behavior and ultimate strength of the reinforced concrete corbel has also been studied
Wang, Lei [Verfasser], e Peter [Akademischer Betreuer] Bruckner. "Specific role of collagen cross-linking enzymes (lysyl oxidase and tissue transglutaminase) in supramolecular organization of matrix in chicken embryonic cornea and tendon / Lei Wang. Betreuer: Peter Bruckner". Münster : Universitäts- und Landesbibliothek der Westfälischen Wilhelms-Universität, 2011. http://d-nb.info/1027018637/34.
Testo completoTidu, Aurélien. "Synthèse d'une cornée artificielle à base de collagène I". Electronic Thesis or Diss., Paris 6, 2016. http://www.theses.fr/2016PA066472.
Testo completoIn view to generate artificial corneas, dense transparent collagen type-I scaffolds were synthesized exploiting the intrinsic liquid crystals properties of collagen molecules. 3 mg/mL collagen solutions in 500 mM acetic acid were dialyzed against a solution of precise concentrations in acetic and hydrochloric acid. When concentrated, solution provided a liquid-crystal organization resembling plywood, which is the organization of the collagen fibrils in the cornea. This was verified by polarized light and second harmonic generation microscopy experiments. In parallel these collagen solutions were also concentrated by centrifugation-filtration up to 90 mg/mL. The concentrated solutions were pressed into cornea-like shape and submitted to ammonia vapor in order to induce the fibrillogenesis of collagen. The result is a transparent dense fibrillated collagen matrix (transparency 90 %). Transmission electron microscopy revealed that fibrils kept the organization of the concentrated solution. Using a custom made device, mechanical tests showed that the Young modulus reached 900kPa. Human donor limbal explants were sewed on top of the scaffolds and cultured for 14 days. Optical microscopy and immunocytochemical analysis showed the development of an epithelium with characteristics of corneal epithelial cells. Preliminary experiments showed that keratocytes could be successfully inserted during the synthesis process. Thus, the results show the viability of the process of fabrication, and the following step is the in vivo experiment
Montezuma, Ronaldo. "Perfil de textura em conserva de carne bovina (Corned Beef) submetida a diferentes tratamentos térmicos e sua relação com a concentração das proteínas dos tecidos muscular e conjuntivo colagenoso /". São José do Rio Preto : [s.n.], 2010. http://hdl.handle.net/11449/90779.
Testo completoBanca: Pedro Fernando Romanelli
Banca: Marcos Franke Pinto
Resumo: O objetivo desta pesquisa foi determinar o Perfil de Textura (TPA) em formulações comerciais de "carne bovina em conserva" (corned beef) enlatada processada termicamente e avaliar sua relação com os valores de esterilização (F0), com a Concentração da Proteína do Tecido Conjuntivo Colagenoso (CCTP) e com a Concentração da Proteína do Tecido Muscular (MTP). Foram selecionados 14 lotes de produção de corned beef em latas tronco trapezoidais de 340 g correspondentes ao padrão continental Campden A e destes foram retiradas 24 latas do produto dos sub lotes submetidos ao processamento térmico. Destas latas foram retiradas seis amostras aleatórias para determinação do TPA e para análise da composição visando determinação da Proteína do Tecido Conjuntivo Colagenoso (CCTP), da Proteína do Tecido Muscular (MTP) e do Conteúdo Carne Magra (LMC). As latas de corned beef analisadas foram submetidas a tratamentos térmicos de 75,0 a 76,7 minutos, com a temperatura da autoclave a 121o C e resfriamento a 35o C durante 60 minutos, obtendo-se valores de F0 no centro de massa do produto variando de 14,8 a 20 minutos. Os parâmetros de TPA dureza, fraturabilidade, coesividade, elasticidade, adesividade, mastigabilidade, gomosidade e resiliência foram determinados no bloco integral do produto bloco resfriado a 4ºC em oito pontos na superfície. Os mesmos blocos do produto utilizados para determinação do TPA foram analisados quanto à composição média, apresentando concentração de 0,4 a 2,5% para CCTP, de 21,7 a 25,3% para MTP e de 102,79 a 107,95% para LMC. Os tratamentos de corned beef avaliados apresentaram diferenças significativas pelo teste de Tukey nas médias dos parâmetros dureza, gomosidade, mastigabilidade, adesividade e elasticidade. Os três primeiros parâmetros apresentaram correlações significativas fortemente negativas com o valor... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The objectives of this research were the determination of the texture profile of canned corned beef thermally processed and to evaluate its relationship with the sterilization value (F0) and the composition. Fourteen production batches of Campden A grade 340-g corned beef cans were selected, from which twenty-four cans of the thermal process sub-batches were retrieved. From the sub-batches, six random sample cans were taken and its content submitted to the Texture Profile Analysis (TPA) and to the composition analysis to determine the concentration of the Collagenous Connective Tissue Protein (CCTP), the Muscular Tissue Protein (MTP) concentration and the Lean Meat Content (LMC). The corned beef samples analyzed were submitted to thermal treatments at 121o C (retort steam temperature) for varying heating times, from 75 to 76 minutes and cooled at 35o C (retort water temperature) during 35 minutes, to obtain F0 values at the product center point varying from 14.8 to 20 minutes. The TPA parameters were determined in 8 points of the whole corned beef loaf of each sample, previously chilled and stabilized at 4o C temperature, to obtain hardness, fracturability, cohesiveness, elasticity, adhesiveness, springiness, gumminess, chewiness and resilience. The same sample material were then analyzed in terms of average composition of the product, resulting in concentrations in the range of 0.4 to 2.5% for CCTP, 21.7 to 25.3% for MTP and content from 102.8% to 108.0% for LMC. The treated corned beef samples analyzed showed significant differences in the means for hardness, adhesiveness, chewiness and elasticity. These parameters showed dependence with the sterilization value (F0), revealing negative strong significant correlation for F0 with hardness, gumminess and chewiness. The MTP and LMC values showed a high positive significant correlation with cohesiveness. It was observed a high... (Complete abstract click electronic access below)
Mestre
Ge, Cheng. "Novel technologies for cell culture and tissue engineering". Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:ab1014cf-80a4-4675-b607-96dc52c39b17.
Testo completoMontezuma, Ronaldo [UNESP]. "Perfil de textura em conserva de carne bovina (Corned Beef) submetida a diferentes tratamentos térmicos e sua relação com a concentração das proteínas dos tecidos muscular e conjuntivo colagenoso". Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/90779.
Testo completoO objetivo desta pesquisa foi determinar o Perfil de Textura (TPA) em formulações comerciais de “carne bovina em conserva” (corned beef) enlatada processada termicamente e avaliar sua relação com os valores de esterilização (F0), com a Concentração da Proteína do Tecido Conjuntivo Colagenoso (CCTP) e com a Concentração da Proteína do Tecido Muscular (MTP). Foram selecionados 14 lotes de produção de corned beef em latas tronco trapezoidais de 340 g correspondentes ao padrão continental Campden A e destes foram retiradas 24 latas do produto dos sub lotes submetidos ao processamento térmico. Destas latas foram retiradas seis amostras aleatórias para determinação do TPA e para análise da composição visando determinação da Proteína do Tecido Conjuntivo Colagenoso (CCTP), da Proteína do Tecido Muscular (MTP) e do Conteúdo Carne Magra (LMC). As latas de corned beef analisadas foram submetidas a tratamentos térmicos de 75,0 a 76,7 minutos, com a temperatura da autoclave a 121o C e resfriamento a 35o C durante 60 minutos, obtendo-se valores de F0 no centro de massa do produto variando de 14,8 a 20 minutos. Os parâmetros de TPA dureza, fraturabilidade, coesividade, elasticidade, adesividade, mastigabilidade, gomosidade e resiliência foram determinados no bloco integral do produto bloco resfriado a 4ºC em oito pontos na superfície. Os mesmos blocos do produto utilizados para determinação do TPA foram analisados quanto à composição média, apresentando concentração de 0,4 a 2,5% para CCTP, de 21,7 a 25,3% para MTP e de 102,79 a 107,95% para LMC. Os tratamentos de corned beef avaliados apresentaram diferenças significativas pelo teste de Tukey nas médias dos parâmetros dureza, gomosidade, mastigabilidade, adesividade e elasticidade. Os três primeiros parâmetros apresentaram correlações significativas fortemente negativas com o valor...
The objectives of this research were the determination of the texture profile of canned corned beef thermally processed and to evaluate its relationship with the sterilization value (F0) and the composition. Fourteen production batches of Campden A grade 340-g corned beef cans were selected, from which twenty-four cans of the thermal process sub-batches were retrieved. From the sub-batches, six random sample cans were taken and its content submitted to the Texture Profile Analysis (TPA) and to the composition analysis to determine the concentration of the Collagenous Connective Tissue Protein (CCTP), the Muscular Tissue Protein (MTP) concentration and the Lean Meat Content (LMC). The corned beef samples analyzed were submitted to thermal treatments at 121o C (retort steam temperature) for varying heating times, from 75 to 76 minutes and cooled at 35o C (retort water temperature) during 35 minutes, to obtain F0 values at the product center point varying from 14.8 to 20 minutes. The TPA parameters were determined in 8 points of the whole corned beef loaf of each sample, previously chilled and stabilized at 4o C temperature, to obtain hardness, fracturability, cohesiveness, elasticity, adhesiveness, springiness, gumminess, chewiness and resilience. The same sample material were then analyzed in terms of average composition of the product, resulting in concentrations in the range of 0.4 to 2.5% for CCTP, 21.7 to 25.3% for MTP and content from 102.8% to 108.0% for LMC. The treated corned beef samples analyzed showed significant differences in the means for hardness, adhesiveness, chewiness and elasticity. These parameters showed dependence with the sterilization value (F0), revealing negative strong significant correlation for F0 with hardness, gumminess and chewiness. The MTP and LMC values showed a high positive significant correlation with cohesiveness. It was observed a high... (Complete abstract click electronic access below)
Vase, Ajoy. "The effect of materials preparation on polymer surfaces". Pomona College, 2007. http://ccdl.libraries.claremont.edu/u?/stc,25.
Testo completoSchmeltz, Margaux. "Microscopie de second harmonique résolue en polarisations linéaire et circulaire pour caractériser l'organisation 3D du collagène". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLX074.
Testo completoCollagen is a major component of organ architecture in mammals where it forms various three-dimensional (3D) structures specific to each tissue. The visualization of this multi-scale 3D organization is crucial to decipher the structure of organs such as the cornea or the skin and to guide the engineering fully functional tissue substitutes. Moreover, the organization of collagen is also affected in many diseases, so that in situ quantitative characterization of such disorders is a major biomedical issue.SHG microscopy has been recognized for several years as the gold-standard technique for imaging fibrillar collagen in situ in unmarked tissues with excellent contrast. This thesis presents the development and the application of new polarization-based SHG microscopy modalities to obtain reliable and quantitative parameters in order to more accurately describe the three-dimensional structure of collagen.First, we present a modality using linear incident polarizations (P-SHG) to analyze the multi-scale organization of collagen in various tissues, healthy and pathological. These analyses were carried out on cultural heritage objects (parchments, made of collagen from animal skins) as well as on biological tissues (corneas). On one hand, taking advantage of the non-invasive nature of this modality, we characterize the degradation of collagen in ancient parchments, precious objects of art and history. This proves the interest of SHG microscopy in the field of cultural heritage, particularly to decipher the state of conservation of objects rich in collagen. On the other hand, quantitative imaging of healthy human corneas is presented, and compared to corneas with keratoconus, a common pathology today. Murine models of corneal keratoconus are also being studied to validate their relevance.Finally, a modality using circular incident polarizations to measure circular dichroism signals (CD-SHG) is exposed. First, we present the rigorous experimental implementation of this modality, by identifying and correcting typical artifacts of this technique. Secondly, we propose a new theoretical approach to describe CD-SHG signals. Numerical simulations of the obtained analytical expression are compared to experimental results in order to understand the evolution of CD-SHG signals with the 3D architecture of collagen
Nazari, Hashemi Parvin Sadat. "Analyse protéomique et propriétés de ré-épithélialisation des membranes amniotiques humaines en vue d'une greffe de la surface oculaire". Thesis, Normandie, 2019. http://www.theses.fr/2019NORMR085/document.
Testo completoThe Human Amniotic Membrane (HAM) graft allows the healing of corneal ulcers and rescues a significant number of eyes with chemical burn. HAM is a biological material, its use for the treatment of ocular surface diseases gives good results because of its ability to reduce inflammation and promote rapid epithelialization. For its clinical use, the HAM must of course be sterile, but also easy to transport from the sampling center to the transplant center, and easily storable and for a long time. Currently on routine in the tissue bank of Rouen, the amniotic membrane is separated from the amnion and denuded of its spongy layer. Subsequently this membrane is stored by cryopreservation (freezing at -80 ° C) which potentially complicates the delivery of membranes. Consequently, as part of this study with the Banque Normande de Cornées of Rouen University Hospital, we have developed freeze-drying of HAM to facilitate its use and distribution. The HAM mapping study will also determine whether the level of growth factors is homogeneous in the HAM or whether it depends on its distance from the umbilical cord. The study of the in vivo biocompatibility of a second material composed of collagen also allows us to consider an alternative for implantation at the level of the stroma. Our protein analyzes (ELISA and Label-free) of freeze-dried HAM do not show any significant difference in terms of quantity and protein quality. The proteomic approach is complemented by the analysis of the ability of human corneal epithelial cells (CECs) to multiply on the freeze-dried amniotic membrane in vitro. We did not observe any difference between the epithelial cells growths on freeze-dried or frozen HAM. The analysis of the extracted protein total also shows that freeze-drying does not degrade the HAM at the protein level. At the structural level the electron microscopy results showed that the structure of the MAH stroma is impacted by freeze-drying. The MAH transplant performed on corneal ulcers in rabbits was performed. During the experiment the rabbits did not show any sign of inflammation, the histological analyzes highlighted the epithelialization of the ocular surface.This project is in collaboration with OSF association for the development of the clinical use of MAHL responding in particular to humanitarian needs (Cameroon). Our study of HAM mapping also showed that variability in terms of amount of protein exists between different donors. We have also shown that the spongy layer is an important source of important growth factor in the healing process of corneal ulcers
El, Khoury Yasmina-Mia. "Artificial collagen for cornea repair". Thesis, 2020. http://hdl.handle.net/1866/24519.
Testo completoPatients with cornea blindness resulting from disease or injury in many countries are unlikely to be transplanted with human donor corneas due a worldwide severe shortage of donor tissues. However, even if donor corneas were available, patients with inflammation or severe disease would not be helped as they are at a high risk of rejecting donor corneas as these contain allogeneic cells. Cell-free corneal implants that do not trigger rejection were developed as alternatives to human donor transplantation by the Griffith lab, and shown in a first-in-human clinical trial to stably regenerate corneal tissue and nerves. These implants comprised recombinant human collagen, the main structural protein found in the human cornea. However, full-length collagens are difficult and expensive to produce, and cannot be customized. A wide variety of shorter peptides that mimic collagen and other extracellular matrix molecules have been developed and tested. This includes hybrid peptides combining collagen and silk (VBsilk). The aim of my thesis is to is to confirm simulations of VBsilk, a hybrid collagen-silk peptide that was produced in the Griffith Lab. A further aim is to determine the conditions for the production and purification to show that simulated peptide can be converted into an actual peptide. Briefly, the DNA coding for a VBsilk sequence was cloned into ClearColi, a strain of E. coli with low endotoxin. The bacteria were grown up in large volume cultures. The VBsilk was extracted and purified by FPLC. SDS-PAGE showed that appropriate-sized bands of protein were obtained. Hence, it is possible to produce VBsilk peptide.
Reinštein, Merjavá Stanislava. "Fenotypická charakterizace zdravé lidské rohovky a její změny při zadní polymorfní dystrofií rohovky". Doctoral thesis, 2011. http://www.nusl.cz/ntk/nusl-311376.
Testo completoGonçalves, Diana Filipa Valbom. "Regularização Corneana com Cross- Linking Guiado por Topografia para o Tratamento do Queratocone". Master's thesis, 2020. http://hdl.handle.net/10316/97777.
Testo completoIntrodução: O Cross-Linking (CXL) é uma terapêutica em evolução para o tratamento do queratocone em progressão. Os tratamentos convencionais mostraram ser capazes de estabilizar a progressão mas a sua incapacidade de reabilitar a visão é uma insuficiência importante. Com o protocolo clássico, a superfície da córnea é irradiada uniformemente com UVA, independentemente da irregularidade que causa o défice visual. Isto significa que a melhoria refrativa e visual associada aos padrões de CXL é, quando presente, imprevisível e incontrolável. Investigações recentes indicam que níveis mais altos de radiação UVA induzem mais achatamento, favorecendo planos de tratamento individualizados que causam um aumento local do efeito do tratamento nas áreas mais afetadas. Relatamos, de seguida, o uso de um novo protocolo de irradiação personalizado para tratar pacientes com queractocone. Com este estudo, colocamos a hipótese de que o uso focal de radiação, em vez de numa zona ampla, levará a um maior achatamento localizado à área do cone (ectásica), menos irregularidades na córnea e melhores resultados visuais.Materiais e métodos: Série de casos prospetiva. Olhos com queratocone progressivo documentado e uma espessura corneana superior a 375 μm foram recrutados. As córneas foram irradiadas usando a Plataforma Mosaic™ KXL-II (Avedro, Waltham, MA, EUA). Perfis de tratamento personalizados são projetados como a superposição de 3 áreas concêntricas centradas no ponto mais fino, apresentado nos mapas do Pentacam. O tratamento começa com uma iluminação de feixe amplo da linha de base incluindo a área periférica mais plana e é continuamente mascarada até que apenas o círculo interno seja irradiado. A exposição à energia é de 5.4J/cm2 no círculo externo e depois aumenta de forma centrípeta para 7.5J/cm2 e 10J/cm2. A acuidade visual para longe corrigida (CDVA), os resultados refrativos e as tomografias de Scheimpflug foram avaliadas.Resultados: Neste estudo prospectivo, 26 olhos de 24 pacientes foram incluídos (idade mínima 17 anos e máxima de 66, com média de idades 28.58 ± 12.05). A espessura média da córnea no pré-operatório foi de 448.00 ± 39.93. O diâmetro médio das áreas tratadas foi de 2.57 ± 0.10, 4.43 ± 0.43, e 6.24 ± 0.54 mm, no círculo interno, médio e externo, respetivamente. O tempo de seguimento médio da nossa população foi de 119.76 ± 39.90 dias [82 - 222]. No último seguimento, a acuidade visual para longe corrigida média melhorou significativamente de 0.4 ± 0.25 logMAR para 0.26 ± 0.13 logMAR (p=0.02). O astigmatismo refrativo (cilindro) médio permaneceu semelhante, de 2.73 ± 2.48 D para 1.99 ± 1.36 D (p=0.26). A esfera média passou de -3.15 ± 3.56 para -3.41 ± 2.04 (p=0.03). A curvatura máxima (Kmax) diminuiu de 58.92 ± 4.68 D para 57.52 ± 7.01 D (p=0.26). O Índice de Variação da Superfície (ISV) também diminuiu significativamente de 105.65 ± 30.85 para 88.46 ± 30.28 (p=0.02). Nenhum paciente desenvolveu complicações significativas durante o seguimento.Conclusão: Os resultados preliminares deste estudo, em que os pacientes foram tratados com um protocolo inovador de CXL, projetado topograficamente e personalizado, parecem mostrar resultados funcionais e tomográficos positivos. No último acompanhamento, observou-se uma melhoria na acuidade visual e uma redução no erro de refração, sugerindo uma vantagem no uso de tratamentos personalizados.
Introduction: Cross-Linking (CXL) is an evolving therapy for the treatment of progressing keratoconus. Conventional treatments have shown to be able to stabilize progression but their inability to rehabilitate vision is an important insufficiency. With the standard protocol, the corneal surface is uniformly irradiated with UVA, regardless of the irregularity causing the visual deficit. This means that the refractive and visual improvement associated with standard CXL is, when present, unpredictable and uncontrollable. Recent investigations indicate that higher levels of UVA radiation induce more flattening, favoring individualized treatment plans that cause a local increase in the effect of treatment in the most affected areas. We report the use of a new personalized irradiation protocol to treat patients with keractoconus. We hypothesize that the focal use of radiation, instead of a wide area, will lead to greater flattening located in the area of the cone (ectatic), less irregularities in the cornea and better visual results.Material and Methods: Prospective case series. Eyes with documented progressive keratoconus and a central corneal thickness greater than 375 μm after epithelial removal were recruited. The corneas were irradiated using the Mosaic™ KXL-II Platform (Avedro, Waltham, MA, USA). Customized treatment profiles are designed as a superposition of 3 areas centered at the apex of the posterior float, displayed on Pentacam maps. Treatment begins from the baseline broad beam illumination, including a flatter peripheral area and is constantly masked until only the inner circle is radiated. The exposure to energy is 5.4J/cm2 in the outer circle and then increases centripetally to 7.5J/cm2 and 10J/cm2. Corrected distance visual acuity (CDVA), refractive results and Scheimpflug tomography were evaluated.Results: In this prospective study, 26 eyes of 24 patients were enrolled (minimum age 17 years and maximum 66, with average age 28.58 ± 12.05). The pre-operative mean central corneal thickness was 448.00 ± 39.93 . Mean diameter for treated areas was 2.57 ± 0.10, 4.43 ± 0.43, and 6.24 ± 0.54 mm fot the inner, medium, and outer circle, respectively. The average follow-up time for our population was 119.76 ± 39.90 days [82 - 222]. At the last followup, the mean CDVA improved significantly from 0.4 ± 0.25 logMAR to 0.26 ± 0.13 logMAR (p=0.02). The average refractive astigmatism remained similar, from 2.73 ± 2.48 D to 1.99 ± 1.36 D (p=0.26). The average refractive sphere changed from -3.15 ± 3.56 to -3.41 ± 2.04 (p=0.03). The maximal curvature (Kmax) decreased from 58.92 ± 4.68 D to 57.52 ± 7.01 D (p=0.26). The Index of Surface Variation (ISV) also significantly decreased from 105.65 ± 30.85 to 88.46 ± 30.28 (p=0.02). None of the patients developed significant complications during the course of the follow-up.Conclusion: Preliminary results from this study, in which patients were treated with an innovative, topographically designed and personalized CXL protocol, seem to show positive functional and tomografic outcomes, induced by customized cross-linking across different areas of the treated cornea. At the last follow-up, an improvement in visual acuity and a reduction in refractive error was noted, suggesting an advantage in the use of customized treatments.
Sylvestre, Daniel Joseph. "Optimizing riboflavin/ultraviolet-a corneal collagen cross-linking for the treatment of progressive keratoconus". Thesis, 2017. https://hdl.handle.net/2144/23839.
Testo completoRowjee, Taruna. "A retrospective analysis of the outcomes in visual acuity and keratometry readings after corneal collagen crosslinking in keratoconus". Thesis, 2017. http://hdl.handle.net/10539/23205.
Testo completoPurpose: To evaluate if corneal collagen crosslinking carried out on patients with keratoconus, slows down or halts the progression of keratoconus. To determine which group of keratoconus patients benefited most from the procedure. Methods: A retrospective record review of 41 eyes of 29 patients. Visual acuity and keratometry measurements were recorded for the involved eye pre-crosslinking and at 3 months and 6 months post-crosslinking. A comparison of these variables pre-crosslinking and at 6 months post-crosslinking was made to determine if there was a flattening of corneal curvature (keratometry readings) and an improvement in visual acuity. Patients were further divided into 3 groups of keratoconus, based on their keratometry readings (measured in diopters): mild keratoconus (≤47 diopters), moderate keratoconus (48 – 54 diopters) and advanced keratoconus (≥55 diopters), to determine which group of keratoconus had the best keratometry reduction readings. Results: After crosslinking took place on 41 eyes, the UnVA of 16(39%) eyes showed an improvement at 6 months, 17(41%) eyes showed no change and 8(20%) eyes showed a decrease in UnVA at 6 months, compared to pre-CXL values. For BCVA, 12(29%) eyes showed an improvement at 6 months, 18(44%) eyes showed no change and 11(27%) eyes showed a decrease in BCVA at 6 months, compared to pre-CXL values. Keratometry readings however showed that 23(56%) eyes had an average flattening of corneal curvature readings of 0.7 D and the remaining 18(44%) eyes showed more steepening (worsening) of the corneal curvature readings of 0.9 D after 6 months post-CXL. 30(73%) eyes had mild keratoconus, 7(17%) had moderate keratoconus and 4(10%) had advanced keratoconus. 19 of the 30 eyes in the mild keratoconus group (73%) showed an average flattening of corneal curvature of 0.6 D. 4 of the 7 eyes in the moderate keratoconus group (17%) showed an average flattening of corneal curvature of 0.7 D. All 4 patients in the advanced group (10%) had steepening (worsening) of their corneal curvatures with an average of 1.2 D. Conclusion: Corneal collagen crosslinking performed on keratoconus patients at least halts the progress of keratoconus. 6 months after CXL most patients showed minimal change from pre-CXL to 6 months in both visual acuity and keratometry. However a longer follow up period and larger sample size is needed to determine if vision and keratometry readings can improve significantly.
MT2017
Arabpour, Z., A. Baradaran-Rafii, N. L. Bakhshaiesh, J. Ai, S. Ebrahimi-Barough, H. E. Malekabadi, N. Nazeri et al. "Design and characterization of biodegradable multi layered electrospun nanofibers for corneal tissue engineering applications". 2019. http://hdl.handle.net/10454/18371.
Testo completoTissue engineering is one of the most promising areas for treatment of various ophthalmic diseases particularly for patients who suffer from limbal stem cell deficiency and this is due to the lack of existence of appropriate matrix for stem cell regeneration. The aim of this research project is to design and fabricate triple layered electrospun nanofibers as a suitable corneal tissue engineering scaffold and the objective is to investigate and perform various in vitro tests to find the most optimum and suitable scaffold for this purpose. Electrospun scaffolds were prepared in three layers. Poly(d, l-lactide-co-glycolide; PLGA, 50:50) nanofibers were electrospun as outer and inner layers of the scaffold and aligned type I collagen nanofibers were electrospun in the middle layer. Furthermore, the scaffolds were cross-linked by 1-ethyl-3-(3 dimethylaminopropyl) carbodiimide hydrochloride and glutaraldehyde. Structural, physical, and mechanical properties of scaffolds were investigated by using N2 adsorption/desorption isotherms, Fourier transform infrared spectroscopy, contact angle measurement, tensile test, degradation, shrinkage analysis, and scanning electron microscopy (SEM). In addition, capability to support cell attachment and viability were characterized by SEM, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, and 4′,6-diamidino-2-phenylindole staining. According to the result of Brunauer–Emmett–Teller analysis, specific surface area of electrospun scaffold was about 23.7 m2 g-1. Tensile tests on cross-linked scaffolds represented more suitable hydrophilicity and tensile behavior. In addition, degradation rate analysis indicated that noncross-linked scaffolds degraded faster than cross-linked one and cross-linking led to controlled shrinkage in the scaffold. The SEM analysis depicted nano-sized fibers in good shape. Also, the in vitro study represented an improved cell attachment and proliferation in the presence of human endometrial stem cells for both cross-linked and noncross-linked samples. The current study suggests the possibility of producing an appropriate substrate for successful cornea tissue engineering with a novel design.
Deputy of Research, Tehran University of Medical Science. Grant Number: 93‐01‐33‐25613