Vascular complications, in microvessels resulting in nephropathy, retinopathy and neuropathy and in macrovessels resulting in atherosclerosis caused by hyperglycemia contribute greatly to the morbidity and mortality in diabetes mellitus. In the vasculature, the endothelial cells (ECs) are first to be damaged by hyperglycemia due to their unique location as the inner lining of all vessels. There are several mechanisms involved in endothelial injury or dysfunction, however, the degradation of heparan sulfate proteoglycan (HSPG) on the cell surface and in the extra cellular matrix (ECM) is considered to be of importance. Heparanase is believed to degrade heparan sulfate (HS). Our objectives were to determine if heparanase is responsible for endothelial injury and dysfunction in diabetes. <p>To determine if hyperglycemia and heparanase cause endothelial injury, high concentrations of glucose (30mM), mimicking hyperglycemia and optimal doses of heparinase I were used to treat cultured porcine aortic endothelial cells (PAECs). Cell injury was measured by determining live cell number and lactate dehydrogenase (LDH) release. To determine if heparanase is expressed in high glucose treated PAECs, reverse transcriptase polymerase chain reaction (RT-PCR) was used to amplify heparanase mRNA. In addition, heparanase activity was measured by incubating cell lysates with 35S-labelled ECM from cultured bovine corneal ECs, where released radioactive HS was analyzed by Sepharose gel filtration followed by â-scintillation counting. To help understand the mechanism of high glucose injury, heparanase mRNA and activity were also measured in PAECs treated with H2O2 or mannitol to determine if free radical injury or osmolarity caused effects similar to high glucose treatment. As well, high glucose or heparinase I treated PAECs were also treated with heparin (0.5 ìg/ml) and/or insulin (1 U/ml) and/or basic fibroblast growth factor (bFGF, 1 ng/ml) to determine if these compounds protected ECs from injury or inhibited heparanase expression induced by high glucose. p* PAECs injured by high glucose or heparinase I (0.3 U/ml in serum free medium) showed a significantly decreased live cell number and increased LDH release compared to control cells. High glucose or heparinase I treated ECs showed an increase in live cell number and decrease in LDH release when treated with heparin and/or insulin and bFGF. Heparanase mRNA and activity was expressed in PAECs treated with high glucose or H2O2. Heparin and/or insulin, but not bFGF prevented heparanase mRNA expression and activity in high glucose treated PAECs. Mannitol did not induce the upregulation of heparanase mRNA and activity. bFGF showed variable protection in cells treated with high glucose or heparinase I when combined with insulin or heparin. <p> From these results we conclude that hyperglycemia is a main cause of endothelial injury. Heparanase production induced by hyperglycemia is responsible for EC injury and vascular dysfunction likely through the degradation of HS, resulting in increased vascular permeability and detachment of cells from the basement membrane. The mechanism of heparanase upregulation may be related to the formation of reactive oxygen species, but not due to changes in osmolarity. Heparin and/or insulin and bFGF protect cells from injury caused by high glucose or heparinase I. Heparin and/or insulin but not bFGF inhibit heparanase mRNA upregulation induced by high glucose. This study provides new insight into the causes of vascular injury associated with diabetes and suggests possible treatments to reduce endothelial injury.

In this dissertation, I investigated computing algorithms for automated retinal blood vessel detection. Changes in blood vessel structures are important indicators of many diseases such as diabetes, hypertension, etc. Blood vessel is also very useful in tracking of disease progression, and for biometric authentication. In this dissertation, I proposed two algorithms to detect blood vessel maps in retina. The first algorithm is based on integration of a Gaussian tracing scheme and a Gabor-variance filter. This algorithm traces the large blood vessel in retinal images enhanced with adaptive histogram equalization. Small vessels are traced on further enhanced images by a Gabor-variance filter. The second algorithm is called a radial contrast transform (RCT) algorithm, which converts the intensity information in spatial domain to a high dimensional radial contrast domain. Different feature descriptors are designed to improve the speed, sensitivity, and expandability of the vessel detection system. Performances comparison of the two algorithms with those in the literature shows favorable and robust results. Furthermore, a new performance measure based on central line of blood vessels is proposed as an alternative to more reliable assessment of detection schemes for small vessels, because the significant variations at the edges of small vessels need not be considered. The proposed algorithms were successfully tested in the field for early diabetic retinopathy (DR) screening. A highly modular code library to take advantage of the parallel processing power of multi-core computer architecture was tested in a clinical trial. Performance results showed that our scheme can achieve similar or even better performance than human expert readers for detection of micro-aneurysms on difficult images.

Maintaining adequate and stable blood oxygen level is important for preterm babies to avoid the risk of brain, lung and retinal injury such as retinopathy of prematurity (ROP). However, wide disparities in policies and practices of oxygenation in preterm babies exist among neonatal care providers as it is still unclear which best method of monitoring and what features of oxygen measurements are important to clinician’s interpretations for assessing preterm babies at risk of developing severe ROP or unstable health condition. This thesis consists of two projects: NZ-ROP that examines multiple factors of severe ROP including summary statistics (mean, standard deviation (SD), coefficient of variation (CV) and desaturation) for oxygen saturation (OS) features in very extreme preterm babies, and NZ-LP that investigates the efficacy of some of these statistics for health monitoring of late preterm babies. The OS data in NZ-ROP were recorded using modified oximeters that have offsets and inherent software artefact, both of which mask the actual saturation for certain OS ranges and may complicate the choice of methods in the analyses. Therefore, novel algorithms involving linear and quadratic interpolations are developed, implemented on the New Zealand data, and validated using the data of a UK preterm baby, as recorded from offsets and non-offsets oximeters. For all data sets, the algorithms produced saturation distributions that were very close to those obtained from the non-offset oximeter. The algorithms perform within the recommended standards of commercial oximeters currently used in the clinical practice. ROP is a multifactorial disease, with oxygenation fluctuations as one of the key contributors. The all-subsets logistic regression, robust and generalised additive statistical modelling, along with a model averaging approach, are applied in NZ-ROP to determine the relationship of variability and level of OS with severe ROP, and the extent of contribution of various clinical predictors to the severity of this eye disease. Desaturation, as a measure of OS variability, has the strongest association with severe ROP among all OS statistics, in particular, the risk of severe ROP is almost three times higher in babies that exhibit greater occurrences of desaturation episodes. Additionally, this study identifies longer periods of ventilation support, frequent desaturation events, extreme prematurity and low birth weight as the most important factors that substantially exacerbate the severity of ROP, and therefore signify babies’ underlying condition of being severely ill. Persistent cardiorespiratory instabilities prior to hospital discharge may expose preterm babies to a greater risk of neuro-developmental impairments. In NZ-LP, the statistical summaries of mean, SD and CV are computed from the OS measurements of healthy stable and unstable babies, and the performance of these statistics in detecting the unstable babies is evaluated using an extremeness index for outlying data and a hierarchical clustering technique. With SD and CV, the clinically unstable babies were very well separated from the group of stable babies, wherein, the separation was even more apparent with the use of CV. These suggest that measures of variability could be better than saturation level for highlighting babies’ underlying instability due to immature physiological systems, but the combination of variability and level through the CV are believed to be even better. Identification and summarisation of useful OS features quantitatively hold great promise for improved monitoring of oxygenation instability and diagnosis of severe ROP for preterm babies.

Previous in vitro studies showed that exchange protein directly activated by cyclic AMP 1 (Epac1), which is a cAMP mediator, plays an important role in maintenance of endothelial barrier function. Diabetic retinopathy is characterized by impairment of retinal blood vessel integrity leading to breakdown of blood retinal barrier, retinal hypoxia, and neuronal damage. Here, we hypothesize that Epac1 regulates endothelial permeability and protects retina from the retinal damage associated with diabetes. To test such hypothesis, we first demonstrated that human retinal microvascular endothelial cells (HRMECs) exposed to high glucose concentration at 25 mM or 35 mM showed the decreased Epac1 expression level. Our preliminary data also showed that Epac1-downstream activator, Rap1, a member of Ras GTPase, was also altered by different glucose levels. In addition, retina from type 2 diabetic, db/db, mice also showed the decreased Epac1 expression compared to that of non-diabetic, db/m, mice. To further determine the role of Epac1 in diabetic retinopathy, we made use of Epac1-deficient mice. The pathogenesis of diabetic retinopathy share similar characteristics to that of ischemic retinopathy, such as neuronal cell death, glial reactivity, and glutamate toxicity. Therefore, we used our previous retinal ischemic model, i.e., transient middle cerebral artery occlusion (tMCAO). Firstly, we determined the retinal morphology of Epac1-/- mice under normal condition at 3wks. At 3 wks old, the Epac1-/- retinae showed a significantly decreased thickness of outer plexiform layer (OPL) with a trend of increase in inner nuclear layer (INL) thickness. Interestingly, there were obviously more glutamine synthetase (GS)-positive M?ller cells and protein kinase C (PKC)-α positive rod bipolar cells in INL. In addition, there were more IgG-positive blood vessels in OPL. To further determine whether these phenotypes will lead to more severe retinal damage, Epac1-/- mice were exposed to 2 hours of MCAO followed by 22 hours of reperfusion, which we have previously shown to induce retinal ischemia. There was no obvious difference in retinal thickness and expressions of glial fibrillary acidic protein (GFAP) and GS in the contralateral sides of Epac1+/+ and Epac1-/- retina after tMCAO suggesting that the Epac1-deficiency may be compensated by either protein kinase A (PKA) or Epac2. However, Epac2 level was not altered by Epac1-deficiency by Western blot analysis. The ipsilateral sides of the retina of Epac1+/+ and Epac1-/- after tMCAO also did not show obvious difference in swelling and cell death in inner retina, GFAP, glutamate, GS, nitrotyrosine (NT), and peroxiredoxin 6 (Prx6), suggesting that Epac1-deficiency may have been compensated by other cAMP mediators, such as Epac2. However, Epac2 expression in the ipsilateral side of Epac1+/+ and Epac1-/- retinae was not significantly different, although the activities of Epac and PKA were not determined. Taken together, the Epac1-deficient mice would serve as a useful model to determine the role of Epac1 in retinal development, and to determine the detail mechanisms of pathogenesis of diabetic and ischemic retinopathy. / published_or_final_version / Anatomy / Master / Master of Philosophy

Objective The main objective is to evaluate the current diabetic retinopathy (DR) screening by optometrists under Risk Assessment and Management Programme (RAMP) in general outpatient clinics (GOPC), and to compare it to conventional screening by clinical examination. The secondary objective is to predict the prevalence of DR and maculopathy (DMac) in the study cohort, and identify risk factors especially the role of nephropathy. Methodology Ophthalmologist’s re-grading of the digital fundus photos previously screened by optometrists according to RAMP protocol was used as the gold standard to evaluate the current screening programme. Accuracy of optometrist screening was calculated by percentage of agreement and Kappa coefficient. Fundus photo grading by ophthalmologist and optometrist was compared to clinical examination findings in eye clinics. Sensitivities and specificities were calculated, and plotted on ROC curve for comparison of the two methods of screening. Prevalences of DR and DMac were estimated from the gold standard grading, and their correlation with other factors also screened by RAMP was identified using chi-square test and logistic regression. Results There was an overall over-grading of disease by optometrists. The overall inter-observer agreement in diagnosis was 81.2%, and the overall kappa coefficient was 0.65 (p<0.001), which reached substantial strength of agreement. Use of mydriatics reduced the percentage of ungradable photos by at least 4 times. The overall agreement of clinical examination with ophthalmologist-photo-grading was 69.2%, and that with optometrist was 60.9%, and the respective Kappa coefficients were 0.31 (p<0.001) and 0.25 (p<0.001). The areas under curve (AUC) on ROC curve were larger for optometrist photo screening (DR=0.85 and DMac=0.80) than clinical examination (DR=0.52 and DMac=0.54). The prevalences of DR and DMac were 19.4% and 3.3% respectively. Duration of DM was the only common significant predictor of referable DR and DMac by chi-square test. 15-year of disease significantly increased the risk of more advanced DR and DMac. Nephropathy was only significant for DR but not DMac. Moderate renal dysfunction as indicated by decreased excretory glomerular filtration rate (eGFR) < 60 mL/min/1.73m2 and presence of macroalbuminuria significantly worsened DR staging, by over 5 times (p=0.02). Family history of diabetes mellitus (DM), on the other hand, increased the risk of DMac only, by 5 times (p=0.01). Conclusion The current optometrists’ screening is reasonably valid and reliable, although there is room for improvement. None-the-less, the higher false-positive rates than false-negative rates for referable disease suggests that it is safer than otherwise. It is a better method than clinical examination. Duration of DM and presence of nephropathy, especially macroalbuminuria which predates decrease in eGFR, and family history of DM can predict more advanced DR and/or DMac development. / published_or_final_version / Public Health / Master / Master of Public Health

No description available.

Thesis (Ph.D.)--University of Adelaide, Dept. of Public Health, 2003. / "January 2003." Bibliography: 10.1-10.11 leaves.

Thesis (Ph. D.)--University of Sydney, 2006. / Title from title screen (viewed Oct. 7, 2009) Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Discipline of Clinical Ophthalmology and Eye Health, Faculty of Medicine. Includes bibliography. Also available in print form.

BACKGROUND: Diabetic retinopathy (DR) is the leading cause of vision loss in the world. The Center for Disease Control and Prevention categorizes those with diabetes into three age groups, including a young adult group, ages 18-44. In the Boston metropolitan area, around 4.6% of this age population has diabetes. EYESPOT is a private eye care practice in Boston. Of the few diabetic patients seen, most do not fall within the young adult age range. Several studies have demonstrated the effectiveness of social media to promote awareness of healthy behaviors. OBJECTIVE: The goal of this study is to utilize social media in order to raise awareness of DR in the young adult population and encourage preventative behavior. METHODS: A Facebook page for EYESPOT Diabetes was created to engage the young adult patient population and was monitored over a four-month period. Four categories of Facebook posts, differentiated by type, were disseminated. Posts were targeted to different audiences during each month, creating three unique time blocks. Posts were analyzed for their Engagement (total number of people who interacted with the post via a “like”, click, or “share”) and their Reach (total number of people that saw the post). Preliminary Engagement measures of each post were standardized to account for measures of Reach, creating an additional measure of standardized engagement scores (SES). A 4x3 ANOVA was conducted using SPSS to evaluate the effects of post type and time block on SES. RESULTS: Main effects were found for both post type and time block. Posts of the “Advertising” type had a significantly lower SES than all other posts (p<.01). Posts in the “Promotional College Student” time block had a significantly higher SES (p<.01) than posts in other blocks. There was a significant type-by-block interaction for SES (p<.01). Post hoc analysis revealed that posts of the “Technological” type had higher SES when posted in the block aimed at College Students (p<.01). Of note, 96% of the Facebook users who saw our posts (n = 4050) fell in the young adult bracket. After the conclusion of the study, two new patients in the young adult range contacted EYESPOT with intent to make future appointments, citing our Facebook page as reference. CONCLUSION: Our study suggests that Facebook may be an effective tool to encourage the young adult population to be aware of and engage in beneficial health behaviors. Future studies will investigate how to utilize social media further to increase physical appointments and patient-clinician interactions.

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / Revisión por pares / INTRODUCCIÓN: Los pacientes con diabetes mellitus tipo 2 son más propensos a una baja calidad de vida, discapacidad e incluso muerte. También, tienen una mayor predisposición a la depresión en comparación con los pacientes no diabéticos; así como una evolución favorable producto de la evaluación e intervención de su salud mental. OBJETIVOS: El objetivo de este estudio fue explorar la presencia de síntomas depresivos en una población ambulatoria con diagnóstico de diabetes mellitus tipo 2 y filiación militar. También examinar los factores asociados a la presencia de síntomas depresivos. MÉTODOS: Realizamos un estudio transversal en 108 personas con diabetes mellitus tipo 2, durante enero de 2012 en una muestra ambulatoria de un hospital de las fuerzas armadas. Los síntomas depresivos se evaluaron con el test autoaplicado de Zung. Usamos la prueba de Chi-cuadrado para examinar las asociaciones entre síntomas depresivos y los factores asociados de interés. Usamos modelos lineales generalizados crudos y ajustados para estimar las Razones de Prevalencia (RP) de la asociación entre las características clínicas y sociodemográficas con la presencia de síntomas depresivos. RESULTADOS: La prevalencia de sintomatología depresiva fue de 56,5% (intervalo de confianza 95%: 46,6-66,0%). El análisis bivariado mostró como significativa la asociación entre la presencia de síntomas depresivos con las variables: sexo, edad y complicaciones clínicas de la diabetes. En los análisis ajustados, la retinopatía diabética [RP: 1,3; intervalo de confianza 95%: 1,1-1,7], y la neuropatía diabética [RP: 1,4; intervalo de confianza 95%: 1,1-1,7] se asociaron a una mayor presencia de síntomas depresivos luego de considerar el sexo de los participantes. CONCLUSIONES: Observamos una elevada presencia de síntomas depresivos en la población de estudio, especialmente en los pacientes geriátricos o del sexo femenino. También en aquellos con complicaciones tardías de la diabetes mellitus tipo 2, y que probablemente representen la repercusión de la enfermedad en la calidad de vida del paciente. Un abordaje multidisciplinario, con enfoque físico y mental, debe ser considerado ya que podría beneficiar a la evolución de los pacientes con esta concomitancia en Perú.