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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
201

Incidência e fatores de risco para alterações visuais pós-operatórias em idosos / Incidence and risk factors for postoperative visual changes in elderly patients

Badessa, Guinther Giroldo 07 May 2018 (has links)
INTRODUÇÃO: Os relatos de alterações da acuidade visual no pósoperatório são esporádicos e acredita-se que apenas os mais graves estejam descritos na literatura. Trata-se de complicação grave e não existem estudos comparativos de avaliação visual antes e após os procedimentos anestésico-cirúrgicos. OBJETIVOS: Analisar a incidência e os fatores de risco para alterações visuais pós-operatórias em pacientes idosos. MÉTODOS: Após aprovação pela Comissão Institucional de Ética em Pesquisa foram estudados 107 pacientes entre 60 anos e 80 anos submetidos a cirurgias com duração superior a 120 minutos. Pacientes com pontuação inferior a 18 pontos na avaliação cognitiva pelo teste de Mini Mental (MMSE) foram excluídos do estudo e também aqueles candidatos a cirurgia oftalmológica, de coluna, cardiovascular, neurocirurgia, de cabeça e pescoço ou otorrinolaringológica, ou os portadores de distúrbios psiquiátricos ou alterações oftalmológicas significativas. Realizou-se avaliação da acuidade visual no dia anterior à cirurgia e no 3º e 21º dias de pósoperatório, sendo esta última realizada apenas nos pacientes que apresentaram algum tipo de alteração visual no 3º PO. As avaliações da acuidade visual foram realizadas utilizando a tabela de Snellen, tabela de Jaeger, biomicroscopia, tonometria óptica, refração, motilidade ocular e fundoscopia. As variáveis independentes preditoras de risco de alteração visual foram selecionadas pelo modelo de regressão logística múltipla. RESULTADOS: A incidência de alteração visual no 3o PO foi de 19,6% (n=21), dos quais 33% (n=7) persistiram com a alteração visual até o 21o PO. A principal alteração foi encontrada ao exame da tabela de Snellen com redução de 30% (p < 0,05) da acuidade visual no 3o PO. Esta alteração foi acompanhada de aumento da refração e da pressão intraocular. Os pacientes diabéticos tipo II, com aumento da frequência cardíaca após a indução anestésica, redução da saturação de oxigênio ao final da cirurgia e submetidos a cirurgias mais prolongadas apresentaram maior risco de alteração visual pós-operatória. DISCUSSÃO: A avaliação por meio de testes específicos permitiu identificar a incidência de alteração visual pósoperatória em pacientes idosos submetidos a anestesia geral para cirurgias com mais de 120 minutos de duração. Os fatores de risco identificados sugerem que pacientes idosos e diabéticos submetidos a cirurgias prolongadas, com aumento da frequência cardíaca e hipotensão após a indução anestésica, redução da saturação de oxigênio ao final da cirurgia e apresentam maior risco de desenvolvimento de alteração visual pósoperatória. Estudos adicionais sobre as causas e formas de prevenção são desejáveis para a melhor compreensão deste evento adverso / BACKGROUND: Reports of changes in visual acuity in the postoperative period are sporadic and it is believed that only the most serious are described in the literature. It is a serious complication and there are no comparative studies evaluating visual function before and after anestheticsurgical procedures. OBJECTIVES: To analyze the incidence and risk factors for postoperative visual changes in elderly patients. METHODS: After approval by the Institutional Ethics Committee, 107 patients between 60 and 80 years of age and candidates for surgery lasting more than 120 minutes were evaluated. Patients with less than 18 points on the cognitive evaluation by the mini-mental state evaluation (MMSE) were excluded from the study and also those candidates to ophthalmologic, spinal, cardiovascular, neurosurgery, head and neck or otorhinolaryngologic surgery, or those with psychiatric disorders or ophthalmological changes. Visual acuity assessment was performed on the day before surgery and on the 3rd and 21st postoperative days (POD), the latter being performed only in patients who presented some type of visual alteration in the 3rd POD. Visual acuity assessments were performed using the Snellen table, Jaeger table, biomicroscopy, optical tonometry, refraction, ocular motility and fundoscopy. The independent predictors of risk of visual impairment were selected by the multiple logistic regression model. RESULTS: The incidence of visual impairment in the 3rd POD was 19.6% (n = 21), of which 33% (n = 7) persisted with the visual alteration until the 21st POD. The main alteration was found when examining the Snellen chart with a 30% reduction (p < 0.05) in visual acuity in the 3rd POD. This alteration was accompanied by an increase in refraction and intraocular pressure. Type II diabetic patients with increased heart rate after anesthetic induction, reduction of oxygen saturation at the end of surgery, and submitted to more prolonged surgeries presented a greater risk of postoperative visual changes. DISCUSSION: The evaluation through specific tests allowed the identification of the incidence of postoperative visual alteration in elderly patients submitted to general anesthesia for surgeries lasting more than 120 minutes. The risk factors identified suggest that elderly and diabetic patients undergoing prolonged surgeries, with increased heart rate and hypotension after induction, and reduction of oxygen saturation at the end of surgery present a higher risk of developing postoperative visual changes. Additional studies on the causes and forms of prevention are desirable for the better understanding of this adverse event
202

Efeitos biomoleculares do JB-1 (um peptídeo análogo do IGF-1) em um modelo experimental de retinopatia induzida por oxigênio em ratos / Biomolecular effects of jb-1 (an igf-1 peptide analog) in a Rat model of oxygen-induced retinopathy

Zacharias, Romy Schmidt Brock 08 December 2011 (has links)
INTRODUÇÃO: Baixos níveis séricos de fator de crescimento insulin-like I (IGF- 1) ao nascimento têm sido considerados um fator de risco para o desenvolvimento da retinopatia da prematuridade em recém-nascidos prematuros de extremo baixo peso. Isto se deve ao seu papel como fator permissivo para o fator de crescimento endotelial vascular (VEGF) exercer sua função no desenvolvimento normal e patológico dos vasos da retina. OBJETIVO: Testar a hipótese de que a administração do JB-1 (um análogo do IGF-1 que inibe de forma potente a auto-fosforilação do receptor do IGF-1 pelo IGF-1) durante a hiperóxia previne a retinopatia induzida por oxigênio em nosso modelo experimental em ratos. MATERIAL E METODOS: Ratos recém-nascidos foram expostos a 50% de oxigênio com três episódios consecutivos de hipóxia (12% de oxigênio) do nascimento ao 14º dia de vida. Os ratos foram tratados com injeções subcutâneas de 1) JB-1 (1g/d) nos três primeiros dias de vida (JB-1 x3); 2) JB- 1(1g/d) por dias alternados do 1º ao 13º dias de vida (JB-1x7) 3) ou volume equivalente de solução salina. Grupos controles foram criados em ar ambiente nas mesmas condições, exceto pelo ciclo de hiperóxia/ hipóxia. Os grupos foram analisados após a exposição ao oxigênio no 14º dia de vida ou deixados em ar ambiente por mais sete dias até o sacrifício, no 21º dia de vida. Determinou-se as dosagens sistêmicas e oculares de fator de crescimento endotelial vascular (VEGF), receptor tipo1 solúvel do fator de crescimento endotelial vascular (sVEGFR-1) e fator de crescimento insulin-like I (IGF-1), associados a análise da vascularização retiniana e do perfil dos genes relacionados à angiogênese retiniana. RESULTADOS: O tratamento com JB-1x3 resultou em supressão efetiva da retinopatia induzida por oxigênio, sem efeitos adversos no crescimento somático e foi associado a um aumento do sVEGFR-1 quando comparado com o JB-1x7. Ao contrário, o tratamento com JB-1x7 durante a exposição ao oxigênio levou à diminuição do peso corpóreo e níveis mais altos de IGF-1 e VEGF relacionados à presença de tortuosidades vasculares e neovascularização retiniana, quando comparado com as retinas que receberam apenas solução salina. CONCLUSÃO: O tratamento curto e sistêmico com JB-1 durante a hiperóxia resultou em prevenção da retinopatia induzida por oxigênio sem restrição do crescimento somático. Novos estudos devem ser realizados para determinar se o JB-1 pode ser usado em recém-nascidos de extremo baixo peso na prevenção da retinopatia da prematuridade / INTRODUCTION: Low serum insulin growth factor (IGF-1) levels at birth is a risk factor for the development of retinopathy of prematurity in extremely low birth weight infants. This may be due to its role as a permissive factor for vascular endothelial growth factor (VEGF) function in normal and pathologic vascular development. OBJECTIVE: To test the hypothesis that JB-1 (an IGF-1 analog that potently inhibits the autophosphorylation of the IGF-1 receptor by IGF-1) administration during hyperoxia prevents oxygen induced retinopathy in our rat model. MATERIAL AND METHODS: Neonatal rats were exposed to 50% oxygen with brief, clustered, hypoxic (12% oxygen) episodes from birth to day 14. The pups were treated with subcutaneus injections of 1) JB-1 (1g/d) on the first, second, and third day (JB-1x3) 2) JB1 (1g/d) on alternate days from first to day 13 (JB- 1x7); or equivalent volume of saline. Control littermates were raised in room air with all conditions identical except for inspired oxygen. Groups were analyzed after hyperoxia/hypoxia cycling on day 14 or allowed to recover in room air until the 21st day. Systemic and ocular VEGF, soluble VEGFR-1, and IGF-1; retinal vasculature and gene profile of retinal angiogenesis were assessed. RESULTS: JB-1x3 treatment resulted in successful suppression of oxygeninduced retinopathy with no adverse effect on anthropometric growth, which was associated with increased sVEGFR-1 compared to JB-1x7. In contrast, intermittent and long exposure to JB-1 (JB-1x7) during the hyperoxia/hypoxia cycling period resulted in decreased body weight and higher ocular IGF-1 and VEGF levels as well as vascular tortuosity and retinal neovascularization compared with saline treated retinas. CONCLUSION: Systemic treatment with JB-1 during hyperoxia results in successful prevention of oxygen-induced retinopathy with little adverse effects on anthropometric growth. Further confirmatory studies are needed to determine whether systemic JB-1 should be used in extremely low birth weight infants to prevent retinopathy of prematurity
203

Heritable influences in oxygen-induced retinopathy

van Wijngaarden, Peter, petervanwijn@yahoo.com.au January 2006 (has links)
Retinopathy of prematurity, a disease characterised by aberrant retinal vascular development in premature neonates, is a leading cause of blindness and visual impairment in childhood. This work sought to examine differences in the susceptibility of inbred rat strains to oxygen-induced retinopathy, a model of human retinopathy of prematurity. The overriding aim was to identify genetic factors in rats that might be generalisable to humans. Newborn rats of six different strains were exposed to alternating cycles of hyperoxia and relative hypoxia for fourteen days. Rats were removed to room air and killed for analysis immediately, to assess oxygen-induced retinal vascular attenuation, or four days later to evaluate the extent of hypoxia-induced vasoproliferation. Whole flat-mounted retinae were stained with fluorophore conjugated isolectin GS-IB4, and measurement of vascular area was conducted using fluorescence microscopy and video-image analysis. A hierarchy of susceptibility to the inhibitory effects of cyclic hyperoxia and relative hypoxia on postnatal retinal vascularization was identified for the rat strains studied. Susceptibility to vascular attenuation was predictive of the subsequent risk of vascular morphological abnormalities. Cross-breeding experiments between susceptible and resistant strains demonstrated that the susceptible phenotype was dominantly inherited in an autosomal fashion. These studies confirmed an association between ocular pigmentation and retinopathy risk, however the finding of differential susceptibility amongst albino rat strains implicated factors in addition to those associated with ocular pigmentation. Quantitative real-time reverse transcription-polymerase chain reaction was used to compare the retinal expression of angiogenic factor genes in susceptible and resistant strains with the aim of identifying a genetic basis for the strain difference. Eight angiogenic factor genes were selected for study: vascular endothelial growth factor (VEGF); VEGF receptor 2; angiopoietin 2; Tie2; pigment epithelium-derived factor; erythropoietin; cyclooxygenase-2 and insulin-like growth factor-1. The most notable difference between strains was the expression of vascular endothelial growth factor (VEGF) during the cyclic hyperoxia exposure period - higher VEGF expression was associated with relative resistance to retinopathy. Other differences in retinal angiogenic factor gene expression between strains, such as higher expression of VEGF receptor 2 and angiopoietin 2 in resistant strains, appeared to be secondary to those in VEGF. Following cyclic hyperoxia, the expression pattern of angiogenic factor genes changed - messenger RNA levels of hypoxia-induced genes, including VEGF, VEGF receptor 2, angiopoietin 2 and erythropoietin, were significantly higher in those strains with larger avascular areas, than in those strains that were relatively resistant to retinopathy. These findings provide firm evidence for hereditary risk factors for oxygen-induced retinopathy in the rat. Differences in the regulatory effects of oxygen on VEGF expression appear to be central to the risk of retinopathy. The potential relevance of these hereditary factors is discussed in the context of the human disease.
204

Retinal associations of diabetes and vascular disease

Jeganathan, V. Swetha January 2009 (has links)
Background: Diabetes mellitus and vascular diseases have a significant impact on the eye. / Aim: To determine the prevalence, risk factors, and racial/ethnic differences of major eye conditions, particularly retinal conditions, associated with diabetes and vascular diseases. / Scope: To date, the majority of studies have examined the association of retinal vascular calibre and diabetes in predominantly white Caucasian populations. Further elucidation of ethnic differences in effects of hyperglycaemia on early microvascular disease is relevant, particularly amongst Asians where diabetes is likely to see the largest increase in prevalence over the next decade. We therefore examined these findings from three Asian population-based studies, the Singapore Malay Eye Study (n=3280), Singapore Prospective Cohort Study and Singapore Cardiovascular Cohort Study 2 (n=3748). / Results: The prevalence of diabetic retinopathy in the Singapore Malay Eye Study was 35%, and associated with longer duration of diabetes, poorer glycemic and blood pressure control. More importantly, 9.0% had vision-threatening retinopathy, and retinopathy was found in 6.0% of people without diabetes. Retinal vascular calibre changes were incriminated in diseases such as diabetes and hypertension, independent of traditional cardiovascular risk factors. Wider venular calibre was independently associated with early age-related macular degeneration. We also found a novel association between peripheral artery disease and glaucoma, stronger in persons with diabetes, independent of vascular risk factors, supporting the vascular theory of glaucoma. / Implications: Subtle changes in retina, including retinal vascular calibre may be early markers of widespread microvascular changes in diabetes, resulting from chronic hyperglycaemia and other pathogenic processes. These results will have broad implications for understanding the impact of both microvascular and macrovascular complications of diabetes in the Asia Pacific region and targeting relevant therapeutic interventions.
205

Poor Glycemic Control Predicts Increased Neuro-retinal Dysfunction in Adolescents with Type 1 Diabetes

Lakhani, Ekta 15 February 2010 (has links)
Studies demonstrate localized neuro-retinal dysfunction in patients with diabetes and no visible diabetic retinopathy (DR). Poor glycemic control is a strong risk factor for DR. We hypothesized that poor glycemic control predicts increased areas of localized neuro-retinal dysfunction in patients with diabetes. Forty-eight adolescents with diabetes and 45 controls were tested using the standard (103 hexagons) multifocal electroretinogram (mfERG). Negative binomial regression analysis was conducted with number of abnormal hexagons (delayed responses) as the dependent variable and glycated hemoglobin (HbA1c), disease duration, age and sex as covariates. Results indicate that a one-unit increase in HbA1c predicts an 80% (p = 0.002) increase in the number of abnormal hexagons when controlling for age. Increased areas of neuro-retinal dysfunction are predicted by worsening glycemic control in patients with no visible DR. Standard mfERG may be useful in monitoring patients with diabetes and identifying those who may be at risk of developing DR.
206

Poor Glycemic Control is Associated with Neuroretinal Dysfunction in Short-wavelength Cone Pathways of Adolescents with Type 1 Diabetes

McFarlane, Michelle 12 January 2011 (has links)
Studies demonstrate short-wavelength cone pathway dysfunction in patients with diabetes and no clinically visible DR. Poor glycemic control, as measured by hemoglobin A1c (HbA1c), is a strong risk factor for DR. We hypothesized that raised HbA1c was associated with short-wavelength cone sensitive visual evoked potential (S-VEP) and electroretinogram (sERG) dysfunction. Forty adolescents with diabetes and 39 controls were tested using the S-VEP. Latencies to a short-wavelength stimulus were delayed in patients at low contrasts. Patient S-VEP latencies were not associated with HbA1c when controlling for age and time since diagnosis. Twenty-one adolescents with diabetes and 19 controls were tested using the sERG. Implicit times of the b-wave were delayed but not associated with HbA1c when controlling for time since diagnosis.Patient PhNR amplitudes were reduced. A one-unit increase in HbA1c was associated with a 15% sERG PhNR amplitude reduction (p=0.004). The sERG PhNR may be a potential biomarker for DR.
207

Poor Glycemic Control Predicts Increased Neuro-retinal Dysfunction in Adolescents with Type 1 Diabetes

Lakhani, Ekta 15 February 2010 (has links)
Studies demonstrate localized neuro-retinal dysfunction in patients with diabetes and no visible diabetic retinopathy (DR). Poor glycemic control is a strong risk factor for DR. We hypothesized that poor glycemic control predicts increased areas of localized neuro-retinal dysfunction in patients with diabetes. Forty-eight adolescents with diabetes and 45 controls were tested using the standard (103 hexagons) multifocal electroretinogram (mfERG). Negative binomial regression analysis was conducted with number of abnormal hexagons (delayed responses) as the dependent variable and glycated hemoglobin (HbA1c), disease duration, age and sex as covariates. Results indicate that a one-unit increase in HbA1c predicts an 80% (p = 0.002) increase in the number of abnormal hexagons when controlling for age. Increased areas of neuro-retinal dysfunction are predicted by worsening glycemic control in patients with no visible DR. Standard mfERG may be useful in monitoring patients with diabetes and identifying those who may be at risk of developing DR.
208

Poor Glycemic Control is Associated with Neuroretinal Dysfunction in Short-wavelength Cone Pathways of Adolescents with Type 1 Diabetes

McFarlane, Michelle 12 January 2011 (has links)
Studies demonstrate short-wavelength cone pathway dysfunction in patients with diabetes and no clinically visible DR. Poor glycemic control, as measured by hemoglobin A1c (HbA1c), is a strong risk factor for DR. We hypothesized that raised HbA1c was associated with short-wavelength cone sensitive visual evoked potential (S-VEP) and electroretinogram (sERG) dysfunction. Forty adolescents with diabetes and 39 controls were tested using the S-VEP. Latencies to a short-wavelength stimulus were delayed in patients at low contrasts. Patient S-VEP latencies were not associated with HbA1c when controlling for age and time since diagnosis. Twenty-one adolescents with diabetes and 19 controls were tested using the sERG. Implicit times of the b-wave were delayed but not associated with HbA1c when controlling for time since diagnosis.Patient PhNR amplitudes were reduced. A one-unit increase in HbA1c was associated with a 15% sERG PhNR amplitude reduction (p=0.004). The sERG PhNR may be a potential biomarker for DR.
209

Personers upplevelser av att leva med synnedsättning orsakad av diabetesretinopati / People's experiences of living with visual impairment caused by diabetic retinopathy

Eriksson, Anneli, Nilsson, Marianne January 2011 (has links)
Bakgrund: Diabetes är en av de främsta orsakerna till synnedsättning och blindhet. Dåförekomsten av diabetes ökar utgör de synrelaterade komplikationerna ett växande globalt hälsoproblem. En ökad förståelse för hur personer med diabetesretinopati upplever att synnedsättning påverkar deras dagliga kan vara till stor hjälp i mötet med dessa personer. Syfte:Syftet med studien var att beskriva personers upplevelser av att leva med diabetesretinopati. Metod: Studien genomfördes som en allmän litteraturstudie. Vetenskapliga, empiriska studier med kvalitativ och kvantitativ ansats ligger till grund för studien. Resultat: Studiens resultat redovisas utifrån tre olika teman: känsla av delaktighet, känsla av begränsningar och känsla av otillräcklighet. Diskussion: Sjuksköterskan bör vara professionell i mötet med patienten. Kommunikation, undervisning och en helhetssyn av personens upplevelse av sin livssituation ligger till grund för personens vård och behandling. Det är viktigt med hälsofrämjande insatser för att kunna förebygga komplikationer. / Background: Diabetes is one of the leading causes of vision loss and blindness. Since the prevalence of diabetes is increasing, the sight-related complications are a growing global health problem. A better understanding of how people with diabetic retinopathy are experiencing vision loss that affects their daily may be helpful in meeting with these people. Purpose: The purpose of this study was to describe people's experiences of living with diabetic retinopathy. Method: The study was conducted as a general literature review. Scientific, empirical studies using qualitative and quantitative approach is the basis for the study. Results: The results are reported from three different themes: sense of ownership, sense of limitations and feelings of inadequacy. Discussions: Nurse should be professional in the meeting with the patient. Communication, education and a holistic view of the person's experience of their lives is the basis for the person's care and treatment. It is important with health promotion efforts to prevent complications.
210

Neuron-Derived Semaphorin 3A is an Early Inducer of Vascular Permeability in Diabetic Retinopathy

Cerani, Agustin 12 1900 (has links)
La détérioration de la barrière hémato rétinienne et l'oedème maculaire consécutif est une manifestation cardinale de la rétinopathie diabétique (RD) et la caractéristique clinique la plus étroitement associée à la perte de la vue. Alors que l'oedème maculaire affecte plus de 25% des patients souffrant de diabète, les modalités de traitement actuellement disponibles tels que les corticostéroïdes administrés localement et les thérapies anti-VEGF récemment approuvés présentent plusieurs inconvénients. Bien que le lien entre une rupture de l’unité neuro-vasculaire et la pathogénèse de la RD ait récemment été établi, l’influence de la signalisation neuro-vasculaire sur la vasculopathie oculaire diabetique a jusqu’à présent reçu peu d’attention. Ici, à l’aide d’ètudes humaines et animales, nous fournissons la première preuve du rôle essentiel de la molécule de guidage neuronale classique Sémaphorine 3A dans l’instigation de la perméabilité vasculaire maculaire pathologique dans le diabète de type 1. L’étude de la dynamique d’expression de Sémaphorine 3A révèle que cette dernière est induite dans les phases précoces hyperglycèmiques du diabète dans la rétine neuronale et participe à la rupture initiale de la fonction de barrière endothéliale. En utilisant le modèle de souris streptozotocine pour simuler la rétinopathie diabétique humaine, nous avons démontré par une série d’approches analogue que la neutralisation de Sémaphorine 3A empêche de façon efficace une fuite vasculaire rétinienne. Nos résultats identifient une nouvelle cible thérapeutique pour l’oedème maculaire diabétique en plus de fournir d’autres preuves de communication neuro-vasculaire dans la pathogènese de la RD. / The deterioration of the blood retinal barrier and consequent macular edema is a cardinal manifestation of diabetic retinopathy (DR) and the clinical feature most closely associated with loss of sight. While macular edema affects over 25% of patients suffering from diabetes, currently available treatment modalities such as locally administered corticosteroids and recently approved anti-VEGF therapies, present several drawbacks. Although recent insight on the pathogenesis of DR points to a breakdown in the neurovascular unit, neurovascular cross-talk and its influence on diabetic ocular vasculopathy has thus far received limited attention. Here we provide the first evidence from both human and animal studies for the critical role of the classical neuronal guidance cue Semaphorin3A in instigating pathological macular vascular permeability in type I diabetes. Investigation of the dynamics of expression reveal that Semaphorin3A is induced in the early hyperglycemic phases of diabetes within the neuronal retina and precipitates initial breakdown of endothelial barrier function. Using the streptozotocin mouse model as a proxy for human diabetic retinopathy, we demonstrate by a series of orthogonal approaches (gene silencing or treatment with soluble Neuropilin-1 employed as a Semaphorin3A trap), that neutralization of Semaphorin3A efficiently prevents retinal vascular leakage. Our findings identify a new therapeutic target for DME and provide further evidence for neurovascular cross-talk in pathogenesis of DR.

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