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Prevalence of Age-Related Macular Degeneration in Nakuru, Kenya: A Cross-Sectional Population-Based Study
Wanjiku Mathenge,Andrew Bastawrous ,Tunde Peto,Irene Leung,Allen Foster,Hannah Kuper
PLOS Medicine , 2013, DOI: 10.1371/journal.pmed.1001393
Abstract: Background Diseases of the posterior segment of the eye, including age-related macular degeneration (AMD), have recently been recognised as the leading or second leading cause of blindness in several African countries. However, prevalence of AMD alone has not been assessed. We hypothesized that AMD is an important cause of visual impairment among elderly people in Nakuru, Kenya, and therefore sought to assess the prevalence and predictors of AMD in a diverse adult Kenyan population. Methods and Findings In a population-based cross-sectional survey in the Nakuru District of Kenya, 100 clusters of 50 people 50 y of age or older were selected by probability-proportional-to-size sampling between 26 January 2007 and 11 November 2008. Households within clusters were selected through compact segment sampling. All participants underwent a standardised interview and comprehensive eye examination, including dilated slit lamp examination by an ophthalmologist and digital retinal photography. Images were graded for the presence and severity of AMD lesions following a modified version of the International Classification and Grading System for Age-Related Maculopathy. Comparison was made between slit lamp biomicroscopy (SLB) and photographic grading. Of 4,381 participants, fundus photographs were gradable for 3,304 persons (75.4%), and SLB was completed for 4,312 (98%). Early and late AMD prevalence were 11.2% and 1.2%, respectively, among participants graded on images. Prevalence of AMD by SLB was 6.7% and 0.7% for early and late AMD, respectively. SLB underdiagnosed AMD relative to photographic grading by a factor of 1.7. After controlling for age, women had a higher prevalence of early AMD than men (odds ratio 1.5; 95% CI, 1.2–1.9). Overall prevalence rose significantly with each decade of age. We estimate that, in Kenya, 283,900 to 362,800 people 50 y and older have early AMD and 25,200 to 50,500 have late AMD, based on population estimates in 2007. Conclusions AMD is an important cause of visual impairment and blindness in Kenya. Greater availability of low vision services and ophthalmologist training in diagnosis and treatment of AMD would be appropriate next steps. Please see later in the article for the Editors' Summary
Structural and Functional Measures of Efficacy in Response to Bevacizumab Monotherapy in Diabetic Macular Oedema: Exploratory Analyses of the BOLT Study (Report 4)
Sobha Sivaprasad, Roxanne Crosby-Nwaobi, Simona Esposti, Tunde Peto, Ranjan Rajendram, Michel Michaelides, Philip Hykin
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0072755
Abstract: Background To describe structural and functional changes associated with diabetic macular oedema (DMO) treated with intravitreal bevacizumab over 24 months. Methods A post-hoc analysis of the data of 34 patients that completed 24 months follow-up in the intravitreal bevacizumab arm of a prospective, randomized controlled trial (BOLT study) was performed. The outcome measures previously used in clinical trials of intravitreal ranibizumab in DMO were employed to describe the visual acuity and macular thickness changes at 12 and 24 months. Results The standard outcomes of mean change in best corrected visual acuity (BCVA) and central macular thickness (CMT) in participants treated with bevacizumab were comparable to those reported in association with ranibizumab. However, exploratory analyses showed that thick maculae at baseline defined as CMT of ≥400 μm, remained significantly thicker than those <400 μm with intensive bevacizumab therapy, despite a comparable gain in visual acuity at both 12 and 24 months. The proportion of subjects that attained a dry macula doubled in both CMT groups between the 12 and 24-month time-points. Conclusions These findings provide valuable information both for clinical practice and trials. Further studies are required to investigate the impact of intravitreal bevacizumab on retinal thickness profiles in DMO.
Crowdsourcing as a Novel Technique for Retinal Fundus Photography Classification: Analysis of Images in the EPIC Norfolk Cohort on Behalf of the UKBiobank Eye and Vision Consortium
Danny Mitry, Tunde Peto, Shabina Hayat, James E. Morgan, Kay-Tee Khaw, Paul J. Foster
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0071154
Abstract: Aim Crowdsourcing is the process of outsourcing numerous tasks to many untrained individuals. Our aim was to assess the performance and repeatability of crowdsourcing for the classification of retinal fundus photography. Methods One hundred retinal fundus photograph images with pre-determined disease criteria were selected by experts from a large cohort study. After reading brief instructions and an example classification, we requested that knowledge workers (KWs) from a crowdsourcing platform classified each image as normal or abnormal with grades of severity. Each image was classified 20 times by different KWs. Four study designs were examined to assess the effect of varying incentive and KW experience in classification accuracy. All study designs were conducted twice to examine repeatability. Performance was assessed by comparing the sensitivity, specificity and area under the receiver operating characteristic curve (AUC). Results Without restriction on eligible participants, two thousand classifications of 100 images were received in under 24 hours at minimal cost. In trial 1 all study designs had an AUC (95%CI) of 0.701(0.680–0.721) or greater for classification of normal/abnormal. In trial 1, the highest AUC (95%CI) for normal/abnormal classification was 0.757 (0.738–0.776) for KWs with moderate experience. Comparable results were observed in trial 2. In trial 1, between 64–86% of any abnormal image was correctly classified by over half of all KWs. In trial 2, this ranged between 74–97%. Sensitivity was ≥96% for normal versus severely abnormal detections across all trials. Sensitivity for normal versus mildly abnormal varied between 61–79% across trials. Conclusions With minimal training, crowdsourcing represents an accurate, rapid and cost-effective method of retinal image analysis which demonstrates good repeatability. Larger studies with more comprehensive participant training are needed to explore the utility of this compelling technique in large scale medical image analysis.
A Two-phase Decision Support Framework for the Automatic Screening of Digital Fundus Images
Balint Antal,Andras Hajdu,Zsuzsanna Maros-Szabo,Zsolt Torok,Adrienne Csutak,Tunde Peto
Computer Science , 2014, DOI: 10.1016/j.jocs.2012.01.001
Abstract: In this paper we give a brief review on the present status of automated detection systems describe for the screening of diabetic retinopathy. We further detail an enhanced detection procedure that consists of two steps. First, a pre-screening algorithm is considered to classify the input digital fundus images based on the severity of abnormalities. If an image is found to be seriously abnormal, it will not be analysed further with robust lesion detector algorithms. As a further improvement, we introduce a novel feature extraction approach based on clinical observations. The second step of the proposed method detects regions of interest with possible lesions on the images that previously passed the pre-screening step. These regions will serve as input to the specific lesion detectors for detailed analysis. This procedure can increase the computational performance of a screening system. Experimental results show that both two steps of the proposed approach are capable to efficiently exclude a large amount of data from further processing, thus, to decrease the computational burden of the automatic screening system.
Africa and Afrocentric Historicism: A Critique  [PDF]
Tunde Adeleke
Advances in Historical Studies (AHS) , 2015, DOI: 10.4236/ahs.2015.43016
Abstract: Since the dawn of slavery in America, black activists have used Africa to construct a countervailing frame of resistance to oppression. Africa had functioned both as the justification for enslavement and racial discrimination for the dominant white society, and as the counter-hegemonic weapon of resistance and empowerment for blacks. Reacting to subordination and marginalization, modern black intellectuals, borrowing from the past, have equally invoked Africa in their quest for a useable and instrumental historical past with which to counteract the Eurocentric constructions of their heritage and experiences. However, the resultant Afrocentric historicist framing of Africa, as well as its racialized and essentialist character, had only replicated precisely the negative shortcomings of the Eurocentric historiography and black intellectuals were attempting to debunk.
Identification of a Potential Susceptibility Locus for Macular Telangiectasia Type 2
Nancy L. Parmalee, Carl Schubert, Maria Figueroa, Alan C. Bird, Tunde Peto, Mark C. Gillies, Paul S. Bernstein, Krzysztof Kiryluk, Joseph D. Terwilliger, Rando Allikmets, for the MacTel Project
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0024268
Abstract: Macular Telangiectasia type 2 (MacTel) is a relatively rare macular disease of adult onset presenting with distortions in the visual field and leading to progressive loss of visual acuity. For the purpose of a gene mapping study, several pedigrees were ascertained with multiple affected family members. Seventeen families with a total of 71 individuals (including 45 affected or possibly affected) were recruited at clinical centers in 7 countries under the auspices of the MacTel Project. The disease inheritance was consistent with autosomal dominant segregation with reduced penetrance. Genome-wide linkage analysis was performed, followed by analysis of recombination breakpoints. Linkage analysis identified a single peak with multi-point LOD score of 3.45 on chromosome 1 at 1q41-42 under a dominant model. Recombination mapping defined a minimal candidate region of 15.6 Mb, from 214.32 (rs1579634; 219.96 cM) to 229.92 Mb (rs7542797; 235.07 cM), encompassing the 1q41-42 linkage peak. Sanger sequencing of the top 14 positional candidates genes under the linkage peak revealed no causal variants in these pedigrees.
Retinal Arterioles Narrow with Increasing Duration of Anti-Retroviral Therapy in HIV Infection: A Novel Estimator of Vascular Risk in HIV?
Sophia Pathai, Helen A. Weiss, Stephen D. Lawn, Tunde Peto, Leris M. D’Costa, Colin Cook, Tien Y. Wong, Clare E. Gilbert
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0051405
Abstract: Objectives HIV infection is associated with an increased risk of age-related morbidity mediated by immune dysfunction, atherosclerosis and inflammation. Changes in retinal vessel calibre may reflect cumulative structural damage arising from these mechanisms. The relationship of retinal vessel calibre with clinical and demographic characteristics was investigated in a population of HIV-infected individuals in South Africa. Methods Case-control study of 491 adults ≥30 years, composed of 242 HIV-infected adults and 249 age- and gender-matched HIV-negative controls. Retinal vessel calibre was measured using computer-assisted techniques to determine mean arteriolar and venular diameters of each eye. Results The median age was 40 years (IQR: 35–48 years). Among HIV-infected adults, 87.1% were receiving highly active antiretroviral therapy (HAART) (median duration, 58 months), their median CD4 count was 468 cells/μL, and 84.3% had undetectable plasma viral load. Unadjusted mean retinal arteriolar diameters were 163.67±17.69 μm in cases and 161.34±17.38 μm in controls (p = 0.15). Unadjusted mean venular diameters were 267.77±18.21 μm in cases and 270.81±18.98 μm in controls (p = 0.07). Age modified the effect of retinal arteriolar and venular diameters in relation to HIV status, with a tendency towards narrower retinal diameters in HIV cases but not in controls. Among cases, retinal arteriolar diameters narrowed with increasing duration of HAART, independently of age (167.83 μm <3 years of HAART vs. 158.89 μm >6 years, p-trend = 0.02), and with a HIV viral load >10,000 copies/mL while on HAART (p = 0.05). HIV-related venular changes were not detected. Conclusions Narrowing of retinal arteriolar diameters is associated with HAART duration and viral load, and may reflect heightened inflammatory and pro-atherogenic states of the systemic vasculature. Measurement of retinal vascular calibre could be an innovative non-invasive method of estimating vascular risk in HIV-infected individuals.
The Reading of Components of Diabetic Retinopathy: An Evolutionary Approach for Filtering Normal Digital Fundus Imaging in Screening and Population Based Studies
Hongying Lilian Tang, Jonathan Goh, Tunde Peto, Bingo Wing-Kuen Ling, Lutfiah Ismail Al turk, Yin Hu, Su Wang, George Michael Saleh
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0066730
Abstract: In any diabetic retinopathy screening program, about two-thirds of patients have no retinopathy. However, on average, it takes a human expert about one and a half times longer to decide an image is normal than to recognize an abnormal case with obvious features. In this work, we present an automated system for filtering out normal cases to facilitate a more effective use of grading time. The key aim with any such tool is to achieve high sensitivity and specificity to ensure patients' safety and service efficiency. There are many challenges to overcome, given the variation of images and characteristics to identify. The system combines computed evidence obtained from various processing stages, including segmentation of candidate regions, classification and contextual analysis through Hidden Markov Models. Furthermore, evolutionary algorithms are employed to optimize the Hidden Markov Models, feature selection and heterogeneous ensemble classifiers. In order to evaluate its capability of identifying normal images across diverse populations, a population-oriented study was undertaken comparing the software's output to grading by humans. In addition, population based studies collect large numbers of images on subjects expected to have no abnormality. These studies expect timely and cost-effective grading. Altogether 9954 previously unseen images taken from various populations were tested. All test images were masked so the automated system had not been exposed to them before. This system was trained using image subregions taken from about 400 sample images. Sensitivities of 92.2% and specificities of 90.4% were achieved varying between populations and population clusters. Of all images the automated system decided to be normal, 98.2% were true normal when compared to the manual grading results. These results demonstrate scalability and strong potential of such an integrated computational intelligence system as an effective tool to assist a grading service.
Competitiveness of Togolese Banking Sector  [PDF]
Tunde Ahmed Afolabi
Theoretical Economics Letters (TEL) , 2018, DOI: 10.4236/tel.2018.811161
Abstract: Development of a country depends on its economic growth which depends also on several factors which can be both micro and macroeconomic. The financial sector is the lung of the economy; more exactly the banking sector contributes in a non negligible part to this growth. The competitiveness, effectiveness and efficiency of banking sector make it reliable to the economy. Unfortunately, evidences have shown that most Sub-Saharan countries don’t rely much on their financial sector, mainly due to challenges they face. This paper aims to analyze the competitiveness and the driving factors in Togolese banking sector with macroeconomic development using Structure-Conduct and Performance (SCP) framework and regression models. The research covers a period of sixteen years (from 2000 to 2015), with ten banks. This research proxies the asset in a panel A and profit in a panel B for the bank’s competitiveness. The results are of panel regressions with fixed effects and robust standard errors. Considering the Panel A, the variables Inter-Banks loans, customers loans, Inter-Banks Debts, Customers Debts are the driving factor of the competitiveness. However, the size of the bank proxied by profit has no impact on the competitiveness. The result suggests that the reform which has started since 1990 should be completed; there should be organizational and financial restructuring.
Biodiesel for Sustainable Energy Provision in Developing Countries  [PDF]
Moses Tunde Oladiran, Jerekias Gandure
Low Carbon Economy (LCE) , 2011, DOI: 10.4236/lce.2011.23017
Abstract: Consumption of fossil fuel resources has been growing over the years and it is the kernel of economic development. However combustion which takes place principally in automobiles, power generation and industrial plants produces greenhouse gases (GHG) that are harmful to the environment. The release of GHG such as carbon dioxide is contributing to global warming. Biofuels can lower carbon footprint, reduce dependence on imported fossil fuels and increase energy security. Integrating biofuels into the national energy mix also has good socio-economic and sustainability potential. Therefore this paper discusses factors for successful diffusion of biodiesel technology in developing economies.
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