Página 1 dos resultados de 803 itens digitais encontrados em 0.014 segundos

Eletrorretinograma de padrão reverso (PERG) de campo total na esclerose múltipla e na neuromielite óptica e PERG multifocal na atrofia em banda do nervo óptico: correlação com os achados da tomografia de coerência óptica e da perimetria c; Pattern-reversal electroretinogram (PERG) full field in multiple sclerosis and optic neuromyelitis and multifocal PERG in band atrophy of the optic nerve: correlation with the findings of optical coherence tomography and computerized perimetry

Hokazono, Kenzo
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 25/04/2014 PT
Relevância na Pesquisa
36.09%
OBJETIVO: avaliar a capacidade do eletrorretinograma de padrão reverso de campo total (PERG) e multifocal (PERGmf) de detectar alterações funcionais da retina em pacientes com afecções desmielinizantes e compressivas da via óptica anterior; estudar a correlação entre as amplitudes do PERG e PERGmf com as espessuras das camadas internas da retina obtidas pela tomografia de coerência óptica (TCO) e com a perda de campo visual avaliada pela perimetria computadorizada padrão (PCP). MÉTODOS: cento e cinquenta e dois olhos de 28 pacientes com esclerose múltipla (EM), 38 com espectro da neuromielite óptica (NMO) com ou sem neurite óptica (NO) prévia e 30 olhos de 26 controles normais foram submetidos ao PERG, à TCO para avaliação da camada de fibras nervosas da retina (CFNR) peripapilar e camadas internas da retina na mácula e à PCP. Os olhos estudados foram divididos em 4 grupos: grupo 1. EM com NO; grupo 2. EM sem NO; grupo 3. NMO; grupo 4. Mielite transversa longitudinal extensa. Os achados foram comparados utilizando-se as equações de estimativas generalizadas. As correlações entre os achados do PERG, da TCO e da PCP foram avaliadas pela correlação de Pearson ou Spearman e pela análise de regressão linear. Para avaliação dos pacientes com doenças compressivas da via óptica anterior...

Uma representação construtiva global para sistemas ordenados de segunda ordem em espaços coerentes intervalares bi-estruturados, com aplicação em matemática intervalar; A global constructive representation of second order ordered systems using bi-structured interval coherence spaces, with an application in interval mathematics

Dimuro, Gracaliz Pereira
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Tese de Doutorado Formato: application/pdf
POR
Relevância na Pesquisa
36.09%
Este trabalho consiste no desenvolvimento de uma metodologia para a obtenção de representações construtivas de sistemas ordenados de 2ª ordem, baseadas em estruturas de espaços coerentes, com aplicação fundamental na Computação Científica e Matemática Intervalar. Obtêm assim uma representação global para os objetos ditos infinitos relativamente ao conteúdo de informação, como números reais e intervalos reais, de tal forma que possam ser definidos modelos semânticos adequados para os processos computacionais envolvendo tais objetos. Esta representação construtiva é denominada de global, pois é realizada em dois níveis distinguíveis, compreendendo não somente a construção interna dos objetos, no contexto de uma da estrutura de informação, mas também sua estrutura externa de aplicação. A estrutura de informação tem caráter compatível com uma abordagem domínio-teorética, e a estrutura de aplicação e determinada pelo use pretendido do sistema representado. Existe um relacionamento entre os dois níveis de construção, garantindo que cada componente da estrutura de aplicação tenha uma representação interna na estrutura de informação. Os sistemas de representação global resultantes são denominados então espaços coerentes bi-estruturados...

Chronic stress disrupts neural coherence between cortico-limbic structures

Oliveira, João F.; Dias, N. S.; Correia, Mariana; Pereira, Filipa Gama; Sardinha, Vanessa Morais; Lima, Ana Raquel; Oliveira, Ana Filipa Martins; Jacinto, L. R.; Ferreira, Daniela; Silva, Ana; Reis, Joana Vanessa Santos dos; Cerqueira, João; Sousa, Nuno
Fonte: Frontiers Media Publicador: Frontiers Media
Tipo: Artigo de Revista Científica
Publicado em /02/2013 ENG
Relevância na Pesquisa
36.13%
The authors would like to thank Rui Gomes for the help in the application of electrophysio- logical techniques and Luís Martins and Miguel Carneiro for the histological preparations.; Chronic stress impairs cognitive function, namely on tasks that rely on the integrity of cortico-limbic networks. To unravel the functional impact of progressive stress in cortico-limbic networks we measured neural activity and spectral coherences between the ventral hippocampus (vHIP) and the medial prefrontal cortex (mPFC) in rats subjected to short term stress (STS) and chronic unpredictable stress (CUS). CUS exposure consistently disrupted the spectral coherence between both areas for a wide range of frequencies, whereas STS exposure failed to trigger such effect. The chronic stress-induced coherence decrease correlated inversely with the vHIP power spectrum, but not with the mPFC power spectrum, which supports the view that hippocampal dysfunction is the primary event after stress exposure. Importantly, we additionally show that the variations in vHIP-to-mPFC coherence and power spectrum in the vHIP correlated with stress-induced behavioral deficits in a spatial reference memory task. Altogether, these findings result in an innovative readout to measure...

Novel metrics for evaluating the functional coherence of protein groups via protein semantic network

Zheng, Bin; Lu, Xinghua
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
45.95%
Metrics are presented for assessing overall functional coherence of a group of proteins based on the associated biomedical literature.

Assessing the functional coherence of gene sets with metrics based on the Gene Ontology graph

Richards, Adam J.; Muller, Brian; Shotwell, Matthew; Cowart, L. Ashley; Rohrer, Bäerbel; Lu, Xinghua
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.09%
Motivation: The results of initial analyses for many high-throughput technologies commonly take the form of gene or protein sets, and one of the ensuing tasks is to evaluate the functional coherence of these sets. The study of gene set function most commonly makes use of controlled vocabulary in the form of ontology annotations. For a given gene set, the statistical significance of observing these annotations or ‘enrichment’ may be tested using a number of methods. Instead of testing for significance of individual terms, this study is concerned with the task of assessing the global functional coherence of gene sets, for which novel metrics and statistical methods have been devised.

Functional Annotation of Hierarchical Modularity

Padmanabhan, Kanchana; Wang, Kuangyu; Samatova, Nagiza F.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 04/04/2012 EN
Relevância na Pesquisa
36.12%
In biological networks of molecular interactions in a cell, network motifs that are biologically relevant are also functionally coherent, or form functional modules. These functionally coherent modules combine in a hierarchical manner into larger, less cohesive subsystems, thus revealing one of the essential design principles of system-level cellular organization and function–hierarchical modularity. Arguably, hierarchical modularity has not been explicitly taken into consideration by most, if not all, functional annotation systems. As a result, the existing methods would often fail to assign a statistically significant functional coherence score to biologically relevant molecular machines. We developed a methodology for hierarchical functional annotation. Given the hierarchical taxonomy of functional concepts (e.g., Gene Ontology) and the association of individual genes or proteins with these concepts (e.g., GO terms), our method will assign a Hierarchical Modularity Score (HMS) to each node in the hierarchy of functional modules; the HMS score and its value measure functional coherence of each module in the hierarchy. While existing methods annotate each module with a set of “enriched” functional terms in a bag of genes, our complementary method provides the hierarchical functional annotation of the modules and their hierarchically organized components. A hierarchical organization of functional modules often comes as a bi-product of cluster analysis of gene expression data or protein interaction data. Otherwise...

Brain functional networks in syndromic and non-syndromic autism: a graph theoretical study of EEG connectivity

Peters, Jurriaan M.; Taquet, Maxime; Vega, Clemente; Jeste, Shafali S; Fernández, Iván; Tan, Jacqueline E; Nelson, Charles A.; Sahin, Mustafa; Warfield, Simon Keith
Fonte: Springer Science + Business Media Publicador: Springer Science + Business Media
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
36.24%
Background Graph theory has been recently introduced to characterize complex brain networks, making it highly suitable to investigate altered connectivity in neurologic disorders. A current model proposes autism spectrum disorder (ASD) as a developmental disconnection syndrome, supported by converging evidence in both non-syndromic and syndromic ASD. However, the effects of abnormal connectivity on network properties have not been well studied, particularly in syndromic ASD. To close this gap, brain functional networks of electroencephalographic (EEG) connectivity were studied through graph measures in patients with Tuberous Sclerosis Complex (TSC), a disorder with a high prevalence of ASD, as well as in patients with non-syndromic ASD. Methods EEG data were collected from TSC patients with ASD (n = 14) and without ASD (n = 29), from patients with non-syndromic ASD (n = 16), and from controls (n = 46). First, EEG connectivity was characterized by the mean coherence, the ratio of inter- over intra-hemispheric coherence and the ratio of long- over short-range coherence. Next, graph measures of the functional networks were computed and a resilience analysis was conducted. To distinguish effects related to ASD from those related to TSC...

Die Rolle des ipsilateralen Motorkortex nach subkortikalem Schlaganfall bei Patienten mit guter klinischer Erholung - Untersuchungen mittels MEG-EMG-Kohärenzanalyse und transkranieller Magnetstimulation; The role of the the ipsilateral motor cortex (iM1) in patients with good functional recovery after subcortical cerebral stroke - investigations with MEG-EMG coherence analysis and transcranial magnetic stimulation (TMS)

Unterseher, Carmen
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
DE_DE
Relevância na Pesquisa
36.28%
Verschiedene Studien unterschiedlichster Methodik (z.B. fMRT, PET, TMS) haben bei Schlaganfallpatienten im chronischen Stadium nach einem subkortikalen Hirninfarkt vermehrte Aktivität über dem zur paretischen Hand ipsilateralen Motorkortex (iM1) beschrieben. In der vorliegenden Arbeit wurde geprüft, ob diese Aktivität Ausdruck der Rekrutierung ungekreuzter kortikospinaler Bahnen ist. Untersucht wurden 10 rechtshändige Patienten mit guter funktioneller Erholung nach einem ersten linkshemisphärischen subkortikalen Infarkt im chronischen Stadium (> 9 Monate nach Ischämie). Das mittlere Alter betrug 52 Jahre, die Altersverteilung lag zwischen 33 und 64 Jahren. Als Einschlusskriterium galt ein nicht hämorrhagischer Infarkt in den Stammganglien, in der Capsula interna oder in der Capsula externa. Die Diagnose musste mit CT oder MRT gesichert sein. Außerdem musste bei allen Patienten zum Zeitpunkt des thrombembolischen Ereignisses eine armbetonte Hemiparese vorliegen, die sich bis zum Zeitpunkt der Messung klinisch verbessert hatte. Als Maß für diese Verbesserung wurde der Paresegrad der MRC- Skala herangezogen. 5 Patienten zeigten pathologische Mitbewegungen der gesunden Hand bei Bewegung der ehemals paretischen Hand. Die Ergebnisse wurden mit den Daten einer altersgematchten Kontrollgruppe im Alter von 44 bis 70 Jahren (mittleres Alter 55...

Hope for GWAS: Relevant Risk Genes Uncovered from GWAS Statistical Noise

Correia, Catarina; Diekmann, Yoan; Vicente, Astrid; Pereira-Leal, José
Fonte: MDPI Publicador: MDPI
Tipo: Artigo de Revista Científica
Publicado em 29/09/2014 ENG
Relevância na Pesquisa
45.95%
Hundreds of genetic variants have been associated to common diseases through genome-wide association studies (GWAS), yet there are limits to current approaches in detecting true small effect risk variants against a background of false positive findings. Here we addressed the missing heritability problem, aiming to test whether there are indeed risk variants within GWAS statistical noise and to develop a systematic strategy to retrieve these hidden variants. Employing an integrative approach, which combines protein-protein interactions with association data from GWAS for 6 common diseases, we found that associated-genes at less stringent significance levels (p < 0.1) with any of these diseases are functionally connected beyond noise expectation. This functional coherence was used to identify disease-relevant subnetworks, which were shown to be enriched in known genes, outperforming the selection of top GWAS genes. As a proof of principle, we applied this approach to breast cancer, supporting well-known breast cancer genes, while pinpointing novel susceptibility genes for experimental validation. This study reinforces the idea that GWAS are under-analyzed and that missing heritability is rather hidden. It extends the use of protein networks to reveal this missing heritability...

Functional coherence and annotation agreement metrics for enzyme families

Bastos, Hugo Paulo da Silva
Fonte: Universidade de Lisboa Publicador: Universidade de Lisboa
Tipo: Tese de Doutorado
Publicado em //2015 ENG
Relevância na Pesquisa
46.27%
Tese de doutoramento, Informática (Bioinformática), Universidade de Lisboa, Faculdade de Ciências, 2015; A range of methodologies is used to create sequence annotations, from manual curation by specialized curators to several automatic procedures. The multitude of existing annotation methods consequently generates an annotation heterogeneity in terms of coverage and specificity across the biological sequence space. When comparing groups of similar sequences (such as protein families) this heterogeneity can introduce issues regarding the interpretation of the actual functional similarity and the overall functional coherence. A direct path to mitigate these issues is the annotation extension within the protein families under analysis. This thesis postulates that the protein families can be used as knowledgebases for their own annotation extension with the assistance of a proper functional coherence analysis. Therefore, a modular framework for functional coherence analysis and annotation extension in protein families was proposed. The framework includes a proposed module for functional coherence analysis that relies on graph visualization, term enrichment and other statistics. In this work it was implemented and made available as a publicly accessible web application...

Hope for GWAS: Relevant Risk Genes Uncovered from GWAS Statistical Noise

Correia, C.; Diekmann, Y.; Vicente, A.M.; Pereira-Leal, J.B.
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em /09/2014 ENG
Relevância na Pesquisa
45.95%
Hundreds of genetic variants have been associated to common diseases through genome-wide association studies (GWAS), yet there are limits to current approaches in detecting true small effect risk variants against a background of false positive findings. Here we addressed the missing heritability problem, aiming to test whether there are indeed risk variants within GWAS statistical noise and to develop a systematic strategy to retrieve these hidden variants. Employing an integrative approach, which combines protein-protein interactions with association data from GWAS for 6 common diseases, we found that associated-genes at less stringent significance levels (p < 0.1) with any of these diseases are functionally connected beyond noise expectation. This functional coherence was used to identify disease-relevant subnetworks, which were shown to be enriched in known genes, outperforming the selection of top GWAS genes. As a proof of principle, we applied this approach to breast cancer, supporting well-known breast cancer genes, while pinpointing novel susceptibility genes for experimental validation. This study reinforces the idea that GWAS are under-analyzed and that missing heritability is rather hidden. It extends the use of protein networks to reveal this missing heritability...

Étude comparative de l'anatomie des plaies de greffe de cornée par tomographie de cohérence optique (OCT)

Alvarez Ferré, Luis
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
FR
Relevância na Pesquisa
36.13%
Cette thèse porte sur l’étude de l’anatomie de la cornée après 3 techniques de greffe soient, la greffe totale traditionnelle (GTT) et des techniques de greffe lamellaire postérieur (GLP) telles que la greffe lamellaire endothéliale profonde (DLEK) et la greffe endothélium/membrane de Descemet (EDMG) pour le traitement des maladies de l’endothélium, telles que la dystrophie de Fuchs et de la kératopathie de l’aphaque et du pseudophaque. Dans ce contexte, cette thèse contribue également à démontrer l’utilité de la tomographie de cohérence optique (OCT) pour l’étude de l’anatomie des plaies chirurgicales la cornée post transplantation. Au cours de ce travail nous avons étudié l'anatomie de la DLEK, avant et 1, 6, 12 et 24 mois après la chirurgie. Nous avons utilisé le Stratus OCT (Version 3, Carl Zeiss, Meditec Inc.) pour documenter l’anatomie de la plaie. L'acquisition et la manipulation des images du Stratus OCT, instrument qui à été conçu originalement pour l’étude de la rétine et du nerf optique, ont été adaptées pour l'analyse du segment antérieur de l’oeil. Des images cornéennes centrales verticales et horizontales, ainsi que 4 mesures radiaires perpendiculaires à la plaie à 12...

Tomografia de coerência óptica na commotio retinae: relato de caso; Optical coherence tomography imaging in commotio retinae: case report

MORITA, Celso; PRETI, Rony Carlos; FERRAZ, Daniel Araújo; MAIA JÚNIOR, Otacílio de Oliveira; TAKAHASHI, Walter Y.
Fonte: Conselho Brasileiro de Oftalmologia Publicador: Conselho Brasileiro de Oftalmologia
Tipo: Artigo de Revista Científica
POR
Relevância na Pesquisa
36.08%
O objetivo deste relato é correlacionar achados à tomografia de coerência óptica e prognóstico visual de pacientes com commotio retina e de gravidades diferentes. Dois pacientes do sexo masculino, de 20 e 23 anos com baixa visual unilateral após trauma ocular contuso atribuível a edema de Berlin foram avaliados pela retinografia e tomografia de coerência óptica. A acuidade visual no olho afetado era de 20/25 no primeiro paciente e conta dedos a 2 metros no segundo. O exame oftalmológico revelou uveíte traumática e, na fundoscopia, evidenciaram-se opacificação retiniana moderada no primeiro caso e grave no segundo. A tomografia de coerência óptica confirmou discreta diminuição da depressão foveal no primeiro caso e desorganização das camadas retinianas no segundo. Houve resolução anatômica e funcional completa a tomografia de coerência óptica no primeiro paciente, enquanto o segundo evoluiu com baixa visual permanente e desorganização da arquitetura retiniana. A tomografia de coerência óptica é um exame complementar útil na avaliação do trauma retiniano, ajudando a entender sua fisiopatologia e predizer prognóstico a partir da análise anatômica da região acometida.; The purpose of this case report was to correlate optical coherence tomography findings and visual outcomes of patients with different degrees of commotio retinae. A 20-year-old male and a 23-year-old male that presented with decreased vision due to Berlin's edema after blunt ocular trauma were evaluated by optical coherence tomography and retinography. The visual acuity in the affected eye was 20/25 in the first patient and counting fingers in the second one. The ophthalmic examination showed traumatic uveitis and fundoscopy revealed mild retinal opacification in the first case and severe opacification in the latter. The optical coherence tomography confirmed the reduction of foveal depression on the first case and the disarrangement of all retinal layers on the second. There has been complete functional and anatomical resolution by optical coherence tomography in the first patient...

Functional Coherence of Insula Networks is Associated with Externalizing Behavior

Abram, Samantha V.; Wisner, Krista M.; Grazioplene, Rachael G.; Krueger, Robert F.; MacDonald, Angus W.; DeYoung, Colin G.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.22%
The externalizing spectrum encompasses a range of maladaptive behaviors, including substance use problems, impulsivity, and aggression. While previous literature has linked externalizing behaviors with prefrontal and amygdala abnormalities, recent studies suggest insula functionality is implicated. The present study investigated the relation between insula functional coherence and externalizing in a large community sample (N=244). Participants underwent a resting functional magnetic resonance imaging scan. Three non-artifactual intrinsic connectivity networks (ICNs) substantially involving the insula were identified after completing independent components analysis. Three externalizing domains—general disinhibition, substance abuse, and callous aggression—were measured with the Externalizing Spectrum Inventory. Regression models tested whether within-network coherence for the three insula ICNs was related to each externalizing domain. Posterior insula coherence was positively associated with general disinhibition and substance abuse. Anterior insula/ventral striatum/anterior cingulate network coherence was negatively associated with general disinhibition. Insula coherence did not relate to the callous aggression domain. Follow-up analyses indicated specificity for insula ICNs in their relation to general disinhibition and substance abuse as compared to other frontal and limbic ICNs. This study found insula network coherence was significantly associated with externalizing behaviors in community participants. Frontal and limbic ICNs containing less insular cortex were not related to externalizing. Thus...

Hope for GWAS: Relevant Risk Genes Uncovered from GWAS Statistical Noise

Correia, Catarina; Diekmann, Yoan; Vicente, Astrid; Pereira-Leal, José
Fonte: MDPI AG Publicador: MDPI AG
Tipo: Artigo de Revista Científica
Publicado em 29/09/2014 ENG
Relevância na Pesquisa
45.95%
Hundreds of genetic variants have been associated to common diseases through genome-wide association studies (GWAS), yet there are limits to current approaches in detecting true small effect risk variants against a background of false positive findings. Here we addressed the missing heritability problem, aiming to test whether there are indeed risk variants within GWAS statistical noise and to develop a systematic strategy to retrieve these hidden variants. Employing an integrative approach, which combines protein-protein interactions with association data from GWAS for 6 common diseases, we found that associated-genes at less stringent significance levels (p < 0.1) with any of these diseases are functionally connected beyond noise expectation. This functional coherence was used to identify disease-relevant subnetworks, which were shown to be enriched in known genes, outperforming the selection of top GWAS genes. As a proof of principle, we applied this approach to breast cancer, supporting well-known breast cancer genes, while pinpointing novel susceptibility genes for experimental validation. This study reinforces the idea that GWAS are under-analyzed and that missing heritability is rather hidden. It extends the use of protein networks to reveal this missing heritability...

Two are better than one: Fundamental parameters of frame coherence

Bajwa, Waheed U.; Calderbank, Robert; Mixon, Dustin G.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.09%
This paper investigates two parameters that measure the coherence of a frame: worst-case and average coherence. We first use worst-case and average coherence to derive near-optimal probabilistic guarantees on both sparse signal detection and reconstruction in the presence of noise. Next, we provide a catalog of nearly tight frames with small worst-case and average coherence. Later, we find a new lower bound on worst-case coherence; we compare it to the Welch bound and use it to interpret recently reported signal reconstruction results. Finally, we give an algorithm that transforms frames in a way that decreases average coherence without changing the spectral norm or worst-case coherence.

Frame Coherence and Sparse Signal Processing

Mixon, Dustin G.; Bajwa, Waheed U.; Calderbank, Robert
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 21/05/2011
Relevância na Pesquisa
36.11%
The sparse signal processing literature often uses random sensing matrices to obtain performance guarantees. Unfortunately, in the real world, sensing matrices do not always come from random processes. It is therefore desirable to evaluate whether an arbitrary matrix, or frame, is suitable for sensing sparse signals. To this end, the present paper investigates two parameters that measure the coherence of a frame: worst-case and average coherence. We first provide several examples of frames that have small spectral norm, worst-case coherence, and average coherence. Next, we present a new lower bound on worst-case coherence and compare it to the Welch bound. Later, we propose an algorithm that decreases the average coherence of a frame without changing its spectral norm or worst-case coherence. Finally, we use worst-case and average coherence, as opposed to the Restricted Isometry Property, to garner near-optimal probabilistic guarantees on both sparse signal detection and reconstruction in the presence of noise. This contrasts with recent results that only guarantee noiseless signal recovery from arbitrary frames, and which further assume independence across the nonzero entries of the signal---in a sense, requiring small average coherence replaces the need for such an assumption.

Assessment of protein set coherence using functional annotations

Chagoyen, Mónica; Carazo, José M.; Pascual-Montano, Alberto
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artículo Formato: 289178 bytes; 75141 bytes; 35264 bytes; application/pdf; application/pdf; application/pdf
ENG
Relevância na Pesquisa
36.25%
12 pages, 5 figures. -- PMID: 18937846 [PubMed].-- PMCID: PMC2588600.-- Additional information available: File 1: Coherence score and significance measures of random sets.- File 2: Functional analysis of 'Module 39' obtained by Pu et al. [37] using various approaches.; [Background] Analysis of large-scale experimental datasets frequently produces one or more sets of proteins that are subsequently mined for functional interpretation and validation. To this end, a number of computational methods have been devised that rely on the analysis of functional annotations. Although current methods provide valuable information (e.g. significantly enriched annotations, pairwise functional similarities), they do not specifically measure the degree of homogeneity of a protein set.; [Results] In this work we present a method that scores the degree of functional homogeneity, or coherence, of a set of proteins on the basis of the global similarity of their functional annotations. The method uses statistical hypothesis testing to assess the significance of the set in the context of the functional space of a reference set. As such, it can be used as a first step in the validation of sets expected to be homogeneous prior to further functional interpretation.; [Conclusions] We evaluate our method by analysing known biologically relevant sets as well as random ones. The known relevant sets comprise macromolecular complexes...

Enhanced Vasculature Imaging of the Retina Using Optical Coherence Tomography

Hendargo, Hansford
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2013
Relevância na Pesquisa
36.14%

Optical coherence tomography (OCT) is a non-invasive imaging modality that uses low coherence interferometry to generate three-dimensional datasets of a sample's structure. OCT has found tremendous clinical applications in imaging the retina and has demonstrated great utility in the diagnosis of various retinal diseases. However, such diagnoses rely upon the ability to observe abnormalities in the structure of the retina caused by pathology. By the time an ocular disease has progressed to the point of affecting the morphology of the retina, irreversible vision loss in the eye may already occur. Changes in the functionality of the tissue often precede changes to the structure. Thus, if imaging methods are developed to provide additional functional information about the behavior and response of the retinal tissue and vasculature, earlier treatment for disease may be prescribed, thus preserving vision for the patient.

Within the last decade, significant technological advances in OCT systems have enabled high-speed and high sensitivity image acquisition using either spectral domain OCT (SDOCT) or swept-source OCT (SSOCT) configurations. Such systems use Fourier processing to extract structural information of a sample from interferometric principles. But such systems also have access to the optical phase information...

Functional Spectral Domain Optical Coherence Tomography Imaging

Bower, Bradley A.
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação Formato: 37908071 bytes; application/pdf
Publicado em //2009 EN_US
Relevância na Pesquisa
36.09%

Spectral Domain Optical Coherence Tomography (SDOCT) is a high-speed, high resolution imaging modality capable of structural and functional resolution of tissue microstructure. SDOCT fills a niche between histology and ultrasound imaging, providing non-contact, non-invasive backscattering amplitude and phase from a sample. Due to the translucent nature of the tissue, ophthalmic imaging is an ideal space for SDOCT imaging.

Structural imaging of the retina has provided new insights into ophthalmic disease. The phase component of SDOCT images remains largely underexplored, though. While Doppler SDOCT has been explored in a research setting, it remains to catch on in the clinic. Other, functional exploitations of the phase are possible and necessary to expand the utility of SDOCT. Spectral Domain Phase Microscopy (SDPM) is an extension of SDOCT that is capable of resolving sub-wavelength displacements within a focal volume. Application of sub-wavelength displacement measurement ophthalmic imaging could provide a new method for imaging of optophysiology.

This body of work encompasses both hardware and software design and development for implementation of SDOCT. Structural imaging was proven in both the lab and the clinic. Coarse phase changes associated with Doppler flow frequency shifts were recorded and a study was conducted to validate Doppler measurement. Fine phase changes were explored through SDPM applications. Preliminary optophysiology data was acquired to study the potential of sub-wavelength measurements in the retina. To remove the complexity associated with in-vivo human retinal imaging...