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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.
1

The effect of normobaric hyperoxia on anatomical and physiological measures in patients with dry age-related macular degeneration

Wang, Justin 31 January 2022 (has links)
PURPOSE: Age-related macular degeneration (AMD) is a complex, progressive ocular disorder that results in outer retinal ischemia and severe vision loss. Dry AMD, the most common form of AMD, is characterized by the build-up of extracellular drusen deposits, dysfunction of the outer retinal layers and degeneration of photoreceptors. This study aimed to examine the anatomic and physiologic effects of short-term normobaric hyperoxia in patients at different stages of dry AMD. METHODS: Twenty-two eyes from 16 patients diagnosed with dry AMD (11 females, 5 males) were used in this study. Eyes were categorized as having either small drusen or drusenoid pigment epithelial detachments (DPEDs) through optical coherence tomography (OCT) imaging. Eyes associated with small drusen received 3-hours of 40% fraction of inspired oxygen (FiO2) normobaric hyperoxia (NBH), whereas eyes associated with DPEDs received either 3-hour NBH or 3-hours of 20% FiO2 normobaric normoxia (NBN). Visual acuity and OCT images of the macula were taken before and after oxygen treatment. Anatomic outcomes consisted of foveal thickness, foveal volume, macular volume and maximum drusen height; visual acuity was the functional outcome. The relationship between maximum drusen height and visual acuity was then examined to determine if these outcomes were associated. RESULTS: Eyes associated with DPED treated with 3-hour NBH had the largest decreases in foveal thickness, foveal volume, macular volume and maximum drusen height. The macular layers were then divided into inner and outer layers. The outer layers, comprised of Bruch’s membrane, drusen and the retinal pigment epithelium, had significant decreases in anatomic outcomes, whereas the inner layers showed no changes. DPED patients treated with 3-hour NBH also had the largest increase in visual acuity following treatment. There was a significant negative correlation between baseline drusen height and baseline visual acuity. For patients with small drusen treated with 3-hour NBH, there were no significant changes to anatomic or functional outcomes. CONCLUSION: The current study demonstrates the efficacy of short-term administration of normobaric hyperoxia in high-risk dry AMD patients with associated DPEDs. Normobaric hyperoxia appears to be a novel and promising treatment that requires further investigation.
2

Non-invasive monitoring of lipofuscin: an imaging technique predictive for age-related macular degeneration

Flynn, Erin Elizabeth 03 November 2016 (has links)
This paper outlines the progression of age-related macular degeneration in the eye and discusses the diagnostic approaches and therapies used currently to treat this disease. Age-related macular degeneration has a complicated pathophysiology involving genetic and environmental factors. This paper focuses its attention on the role of lipofuscin accumulation in this disease. Lipofuscin in the eye refers to the bisretinoid products of the visual cycle. While lipofuscin accumulation is normal in healthy eyes, the excessive accumulation causes retinal dysfunction. Lipofuscin accumulation has been linked heavily not only to age-related macular degeneration but also juvenile macular degeneration, retinitis pigmentosa, Best’s Villiform disease, and many others. New techniques in ophthalmic research have evaluated the role of lipofuscin accumulation in such retinal genetic diseases. This paper proposes an approach to apply techniques such as quantified autofluorescence imaging and high-powered liquid chromatography of bisretinoids in the eye to track the role of lipofuscin accumulation in the progression of age-related macular degeneration.
3

Topical Application of Vasostatin Attenuates the Development of Choroidal Neovascularization in Rats after Laser Photocoagulation

Lin, Hsiu-chen 31 August 2007 (has links)
Age-related macular degeneration (ARMD) is the leading cause for visual impairment and blindness in the elder population of developed countries. The primary underlying cause for significant visual loss is the choroidal neovascularization (CNV). CNV is also generated in high myopia ; angioid streaks and some inflammatory diseases and rarely after laser photocoagulation. Current treatment strategies for ARMD include laser photocoagulation , photodynamic therapy , but neither treatment addresses underlying stimuli for blood vessel growth. Therefore, recurrent disease is a problem of clinical significant relevance. Surgical excision of submacular neovascular membrane lead to the additional damage of the retinal pigment epithelium (RPE). Consequently, use of therapeutic agents that directly inhibit the angiogenic stimuli may be able to provide a more effective and permanent treatment. Vasostatin (VS) , the N-terminal domain (amino acid 1-180) of a calcium-binding protein , is a potent angiogenesis inhibitor , isolated from culture supernatants of an Epstein-Barr virus-immortalized cell line. In previous studies, we demonstrated that gene delivery of angiogenesis inhibitor vasostatin attenuated the corneal neovascularization in animals. The recombinant vasostatin also prevented or apparently reduced growth of human Burkitt lymphoma and human colon carcinoma in animal model. The primary objective of this study was to vasostatin attenuated the choroidal neovascularization in animals. Retinal and visual function will be evaluated. The above experiments would enable us to test the hypothesis that the topical application of VS delivery might be a promising strategy for the treatment of ARMD and other retinal disorders. Furthermore, the results from animal studies might be extrapolated for future clinical application.
4

MOLECULAR PROFILING OF THE MICROBIAL COMMUNITY AND SULFATE- REDUCING BACTERIA ASSOCIATED WITH SIX PILOT SCALE PASSIVE SULFATE- REDUCING BIOREACTORS

Babbitt, Aaron 01 May 2015 (has links)
Acid mine drainage (AMD) is an environmental hazard across the world. Passive bioreactors utilizing sulfate-reducing bacteria to remediate AMD impacted sites are a promising solution due to their low cost and minimal maintenance. This study profiled the microbial community associated with six in situ, pilot scale bioreactors that were constructed with varying ratios of simple and complex organic substrate and exposed to AMD. Samples were analyzed nine and fourteen months post assembly to ascertain long-term performance. The overall microbial and sulfate-reducing communities were analyzed by 16S rRNA gene and dsrA gene sequencing, respectively. Over the fourteen-month experiment, the results indicated that the microbial community shifted from one dominated by heterotrophic and fermentative microorganisms utilizing the available substrates to one commonly found in untreated AMD. Thus suggesting a decrease in bioreactor performance over time. The data also indicated that the overall microbial communities within the test bioreactors possessed similar members, but in different abundance. Thus it is unlikely that substrate composition played a significant role in community diversity. At the end of the study period, sulfide measurements suggested that the bioreactor containing the highest amount of complex substrate (Barrel 6) resulted in the greatest stimulation of sulfate reduction. Analysis of the dsrA genes from the community in Barrel 6 suggested that bacteria related to thermophilic sulfate-reducers were responsible for the increased sulfate reduction in this bioreactor.
5

Progressionsrisiko früher Altersabhängiger Makuladegeneration anhand der Fundusautofluoreszenzmessung

Peters, David Alexander 07 January 2015 (has links) (PDF)
Eine retrospektive Studie über das Progressionsrisiko asymptomatischer früher Altersabhängiger Makuladegeneration in die symptomatische Spätphase überzugehen. Anhand von Lipofuszin-Mustern, die per Fundusautofluoreszenzmessung erkannt werden können, lassen sich Risikopatienten identifizieren. Diese Methode könnte zukünftig im klinischen Alltag als nicht-invasive, kostengünstige Screening-Methode zur Anwendung kommen, um Risikopatienten einer intensivierten Therapie unterziehen zu können, bevor sie eine Beeinträchtigung ihrer Sehkraft erfahren.
6

En jämförelse mellan användandet av högkontrast och lågkontrast-optotyper vid subjektiv refraktion hos patienter med åldersrelaterad makuladegeneration

Karlsson, Elin January 2012 (has links)
Syfte: Syftet med denna studie var att värdera användningen av lågkontrast-optotyper, jämfört med traditionella högkontrast-optotyper, vid subjektiv refraktionering hos individer med åldersrelaterad makuladegeneration. Samt att undersöka om detta ger ett mer exakt refraktionsvärde och därmed bättre syn. Metod: Subjektiv refraktion utfördes mot hög (100 %) och låg (10 eller 25 %) kontrast hos 15 patienter med åldersrelaterad makuladegeneration. Ett objektivt värde i form av ett autorefraktorvärde eller habituell korrektion användes som utgångsläge. Bracketing-teknik, specialbeställda flipprar från Multilens, provbåge, provglas och 3 olika starka korscylindrar (±0,25 DC, ±0,50 DC och ±1,00 DC) användes till refraktionen. Visus mättes i fyra olika kombinationer: korrektionen man fann vid högkontrast-refraktionen mättes mot hög och låg kontrast; och korrektionen man fann vid lågkontrast-refraktionen mättes mot hög och låg kontrast. Resultat: Vektors analys användes för att analysera skillnaderna i refraktionsvärden mellan hög och låg kontrast. T-test visar att det inte finns någon statistiskt signifikant skillnad (p > 0,05) i refraktion mellan de olika kontrasterna. Analys av visusvärden visar att det blir en statistiskt signifikant förbättring (p < 0,05) när visus mäts mot hög i stället för låg kontrast. Dock fann man ingen statistiskt sigifikant skillnad (p > 0,05) då visus mättes mot optotyper med hög/låg kontrast med lågkontrast-refraktionen jämfört med högkontrast-refraktionen. Slutsats: Subjektiv refraktion mot optotyper med låg kontrast kan hos vissa individer med åldersrelaterad makuladegeneration ge något bättre visus. Dock var inte förbättringen av klinisk signifikans och därför ger inte resultaten i denna studie något stöd för att det skulle vara användbart att inkludera lågkontrast-refraktion hos alla individer med AMD.
7

Tanshinone IIA Inhibits VEGF Secretion and HIF-1a Expression in Cultured Human Retinal Pigment Epithelial Cells under Hypoxia

Alzhrani, Rami Mohammed January 2016 (has links)
No description available.
8

BENZENE-1,3-DIAMIDOETHANETHIOL (BDETH2) AND ITS METAL COMPOUNDS

Zaman, Kamruz Md 01 January 2008 (has links)
There is a global need to find a permanent and readily implemented solution to the problem of heavy metal pollution in aqueous environments. A dithiol compound, benzene-1,3-diamidoethanethiol (BDETH2), also known as N,N'-bis(2-mercaptoethyl) isophthalamide or N,N'-bis(2-mercaptoethyl)-1,3-benzenedicarboxamide, capable of binding divalent metal ions, has been synthesized and characterized. A broad range of BDET-metal compounds, spanning the periodic chart, has been prepared and characterized by IR, MS, EA, Raman, XAFS and TGA. The characteristics of the BDET-M compounds were determined through secondary reactions. In an effort to derivatize BDET-M compounds through alkylalumination a new cyclic compound, 1,3- bis(4,5-dihydrothiazolo)benzene, has been synthesized by refluxing BDETH2 in the presence of AlMe3. Mineral coating studies have been performed and it was found that coating with BDET prevents metal leaching. XPS studies indicated that covalent bonds exist between BDET and metals at the mineral surfaces. BDETH2 is not water soluble and must be used as an ethanolic solution to precipitate metals from water. In an effort to find similar ligands that are water-soluble another dithiol compound, N,N'-bis(2-mercaptoethyl)oxalamide (MOA), and a monothiol compound, N-mercaptoethyl-furoylamide (MFA), have been synthesized. Each was found to precipitate Cd, Hg and Pb from water, to varying degrees. Some metal compounds of MOA, MFA and dithiothreitol (DTT), a watersoluble dithiol compound have been prepared and characterized. These compounds provide insight into the properties of the BDET-M compounds. For example, it was shown that insolubility in water is a common feature of thiol compounds and is not unique to BDET-M compounds.
9

Rökningens betydelse för uppkomst och utveckling av åldersrelaterad makuladegeneration

Wahlgren, Ida January 2010 (has links)
<p><strong>Bakgrund</strong>: Åldersrelaterad makuladegeneration (AMD) är den vanligaste orsaken till allvarlig synnedsättning hos den äldre delen av befolkningen i Europa, och övriga högutvecklade delar av världen. Sjukdomen finns i två olika former, en torr och en våt. De främsta riskfaktorerna för sjukdomen är åldern och hereditet, och dessa faktorer kan man inte påverka själv. Påverkbara riskfaktorer som diskuterats är bl.a. rökning, högt blodtryck, övervikt, kostsammansättning och exponering av UV-ljus. Av dessa faktorer är rökning den riskfaktor som är starkast sammankopplad med sjukdomen.</p><p><strong>Syfte: </strong>Studiens syfte är att med hjälp av litteratur ta reda på hur sambandet mellan rökning och AMD ser ut. Det som undersökts i de vetenskapliga studierna och som tas upp i det här arbetet är hur mycket risken att drabbas av AMD ökar för en rökare jämfört med en icke-rökare, samt om det hjälper att sluta röka för att minska denna risk.</p><p><strong>Metod: </strong>Arbetet har gjorts i form av en litteraturstudie. Vetenskapliga artiklar har sökts via sökmotorerna PubMed, Web of science och Google Scholar.</p><p><strong>Resultat: </strong>9 artiklar som presenterar resultatet från studier som gjorts på relationen mellan rökning och AMD har valts ut och presenteras i detta arbete.</p><p><strong>Slutsats: </strong>Flertalet av studierna pekar på att det finns ett samband mellan rökning och AMD.  Risken ökar med antalet cigaretter som rökts under livstiden. Den ökade risken för AMD verkar finnas kvar upp till 20 år efter att en rökare slutat röka. Detta är en anledning för en person som röker att sluta röka redan vid tidig ålder.</p>
10

Antioxidanter förhindrar AMD : Sanning eller myt? / Antioxidants prevent AMD : Truth or myth?

Liljenberg, Anna January 2010 (has links)
<p><strong>Syfte:</strong> Att undersöka ifall ett ökat intag av antioxidanter via kost eller supplement kan förhindra uppkomst och progression av åldersrelaterad makuladegeneration, AMD.</p><p><strong>Metod:</strong> Granskning och sammanställning av publicerade forskningsresultat inom området.</p><p><strong>Resultat: </strong>Av 7 granskade studier visade 5 på en skyddande effekt mot uppkomst eller progression av AMD vid ett ökat intag av antioxidanter. Resterande 2 studier kunde inte finna något signifikant samband. Resultatet varierar för specifika antioxidativa ämnen i olika studier.</p><p><strong>Slutsats:</strong> Forskningen tyder på att ett ökat intag av antioxidanter, antingen via kosten eller supplement, skulle kunna förebygga och bromsa de skador som uppkommer vid AMD. Man bör dock ytterligare utreda eventuella negativa bieffekter vid höga doser av bland annat β-karoten och E-vitamin. Det behövs fler långtidsstudier för att fullt ut förstå samspelet mellan hur olika livsmedel och specifika antioxidanter tas upp och metaboliseras och hur dessa kan påverka uppkomst och progression av AMD.</p>

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