1,720,957 research outputs found
Age-related macular degeneration
No full textAge-related macular degeneration (AMD) is the leading cause of irreversible blindness in the developed world. Despite recent advances in treatment, AMD causes considerable morbidity. For the non-ophthalmologist, a brief background on retinal structure is provided, followed by a description of the characteristic changes seen in AMD. Subsequently the typical clinical features of AMD are discussed with an outline of present management, followed by the current theories of AMD pathogenesis. The similarities between AMD and another neurodegenerative disease are then highlighted. Finally, we review the on-going clinical trials of potential treatments for the future. Since it is clear that multiple risk factors are involved in the pathogenesis of AMD, a multi-faceted approach will most likely be required in order to prevent further patients progressing to blindness as a result of this devastating condition
Oxidation and age-related macular degeneration: insights from molecular biology
No full textAge-related macular degeneration (AMD) is the leading cause of blindness in the developed world. It is a multifactorial disease, and current therapy predominantly limits damage only when it has already occurred. The macula is a source of high metabolic activity, and is therefore exposed to correspondingly high levels of reactive oxygen species (ROS). With age, the balance between production of ROS and local antioxidant levels is shifted, and damage ensues. Systemic ROS and antioxidant levels in AMD reflect these local processes. Genetic studies investigating mutations in antioxidant genes in AMD are inconclusive and further studies are indicated, especially to determine the role of mitochondria. Oral antioxidant supplements could be beneficial, and diet modification may help. Future treatments might either increase antioxidant capacity or reduce the production of ROS, using methods such as genetic manipulation. This article reviews the role of oxidative stress in AMD and the potential therapies that might have a role in preventing the blindness resulting from this disease
Chlamydia infection status, genotype, and age-related macular degeneration
No full textPURPOSE: To evaluate whether Chlamydia (C.) infections are associated with age-related macular degeneration (AMD) and to assess if this association is influenced by the complement factor H (CFH) Y402H or the high temperature requirement A serine peptidase 1 (HTRA1) rs11200638 risk genotypes.METHODS: One hundred ninety-nine AMD patients with early and late forms of the disease and 100 unaffected controls, at least 50 years old were included in the study. Patients in the AMD and control groups were selected based on known CFH Y402H variant genotype status (one third homozygous CC, one third heterozygous CT, and one third wild-type TT). Plasma from all patients and controls was tested for C. pneumoniae, C. trachomatis, and C. psittaci IgG seropositivity using a micro-immunofluorescent assay to establish previous infection status. Assays were conducted blind to risk genotypes and the results analyzed using univariate and multivariate (logistic regression) analysis.RESULTS:IgG seropositivity to C. pneumoniae was most prevalent (69.2%, n=207), followed by C. trachomatis (7.4%, n=22) and C. psittaci (3.3%, n=10). No association was found between each of the three Chlamydia species IgG seropositivity and AMD status or severity (early/late). There was also no significant association between Chlamydia species IgG seropositivity and AMD status or severity, in patients carrying at least one CFH Y402H risk allele (C) or HTRA1 rs11200638 risk allele (A), with univariate or logistic regression analysis. CONCLUSIONS:Chlamydia infection status does not appear to be associated with AMD status or severity. The presence of CFH Y402H and HTRA1 rs11200638 risk genotypes does not alter this negative association
X-linked retinoschisis maculopathy treated with topical dorzolamide, and relationship to genotype.
No full textTopical dorzolamide may have some effect in reducing central macular thickness in patients with XLRS, but this does not necessarily correlate with improvement in VA. In our case series, genotypic information did not predict the response to this treatmen
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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