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Prevention of age related macular degeneration. Current evidence suggests that vitamin E alone is unlikely to have a large protective effect
No full textAge related macular degeneration may be recognised in its early stages by the appearance of drusen and pigment change within the retina, but it produces few symptoms. Progression of age related macular degeneration can result in irreversible visual loss and is the commonest cause of blindness in the Western world. New treatments such as photodynamic therapy and macular surgery may limit the extent of visual loss and in a few cases even restore sight.1 But in contrast with cataract surgery, outcomes are unpredictable and the treatment is burdensome for patients and carries massive resource implications for healthcare providers. The prospect of prevention is thus very appealing from the public health perspective, not to mention that of the patient who may be at risk of losing the ability to recognise faces, read a newspaper, or to live independently. Increasing evidence suggests that cumulative oxidative damage increases risk of age related
Plasma antioxidant vitamins and carotenoids and age-related cataract
No full textObjective: To investigate the relationships between plasma concentrations of antioxidant vitamins and carotenoids and nuclear, cortical, and posterior subcapsular cataracts in a group of elderly men and women.Design: Cross-sectional survey.Participants: Three hundred seventy-two men and women, aged 66 to 75 years, born and still living in Sheffield, England.Methods: The Lens Opacities Classification System (LOCS) III was used to grade nuclear, cortical, and posterior subcapsular lens opacities. Fasting blood samples were taken to assess plasma concentrations of vitamin C, vitamin E, ?-carotene, ?-carotene, lycopene, lutein, zeaxanthin, and ?-cryptoxanthin.Main outcome measures: Logistic regression analyses of the associations between plasma vitamin concentrations and cataract subtype, adjusting for age, gender, and other risk factors.Results: After adjustment for age, gender, and other risk factors, risk of nuclear cataract was lowest in people with the highest plasma concentrations of ?-carotene (odds ratio [OR], 0.5; 95% confidence interval [CI], 0.3–0.9, P for trend 0.006) or ?-carotene (OR, 0.7; 95% CI, 0.4–1.4, P for trend 0.033). Risk of cortical cataract was lowest in people with the highest plasma concentrations of lycopene (OR, 0.4; 95% CI, 0.2–0.8, P for trend 0.003), and risk of posterior subcapsular cataract was lowest in those with higher concentrations of lutein (OR, 0.5; 95% CI, 0.2–1.0, P for trend 0.012). High plasma concentrations of vitamin C, vitamin E, or the carotenoids zeaxanthin and ?-cryptoxanthin were not associated with decreased risk.Conclusions: These findings suggest that a diet rich in carotenoids may protect against cataract development, but because they are based on observational data, they need to be confirmed in randomized controlled trials
Relation between size at birth and risk of age-related macular degeneration
No full textPURPOSE. To determine whether poor fetal growth, as determined by size at birth, is associated with increased risk of age-related macular degeneration. METHODS. A total of 660 men and women born in Sheffield, United Kingdom, between 1922 and 1930 and whose size at birth was available were traced and invited to take part in the study. Of these, 392 attended for ophthalmic examination. Age-related macular degeneration in these volunteers was determined by the Wisconsin Age-Related Maculopathy Grading System. RESULTS. The mean birth weight of subjects with macular degeneration (early or late) was heavier than that of those without (7.6 lb vs. 7.3 lb, respectively; P = 0.03). After adjustment for age, gender, and risk factors for macular degeneration, a significantly increased risk of macular degeneration was found in subjects with higher birth weight (odds ratio [OR] 1.5, 95% confidence interval [CI] 1.1–2.0 for each SD [1 lb, 5 oz] increase in birth weight). Other parameters describing size at birth showed a weaker relation or no relation with macular degeneration, but one of the measures of fetal proportion (head circumference-to-birth weight ratio) was significantly associated with risk of macular degeneration. Subjects with macular degeneration had a significantly lower head circumference-to-birth weight ratio than did those without (11.2 vs. 12.0 respectively, P = 0.01). CONCLUSIONS. The finding that age-related macular degeneration was associated with increased rather than decreased birth weight was unexpected. Failure of the developing fetus’s normal brain-sparing mechanism is a possible explanation for our finding of a lower head circumference-to-birth weight ratio among subjects with macular degeneration. <br/
Lutein and zeaxanthin status and risk of age-related macular degeneration
No full textPURPOSE. To investigate the relation between plasma concentrations of lutein and zeaxanthin and age-related macular degeneration in a group of elderly men and women. METHODS. The Wisconsin Age-Related Maculopathy Grading System was used to grade features of early and late macular degeneration in 380 men and women, aged 66 to 75 years, from Sheffield, United Kingdom. Fasting blood samples were taken to assess plasma concentrations of lutein and zeaxanthin. RESULTS. Risk of age-related macular degeneration (early or late) was significantly higher in people with lower plasma concentrations of zeaxanthin. Compared with those whose plasma concentrations of zeaxanthin were in the highest third of the distribution, people whose plasma concentration was in the lowest third had an odds ratio for risk of age-related macular degeneration of 2.0 (95% confidence interval [CI] 1.0–4.1), after adjustment for age and other risk factors. Risk of age-related macular degeneration was increased in people with the lowest plasma concentrations of lutein plus zeaxanthin (odds ratio [OR] 1.9, 95% CI 0.9–3.5) and in those with the lowest concentrations of lutein (OR 1.7, 95% CI 0.9–3.3), but neither of these relations was statistically significant. CONCLUSIONS. These findings provide support for the view that zeaxanthin may protect against age-related macular degeneration. <br/
Myopia and polmorphisms in genes for matrix metalloproteinases
No full textPURPOSE. To investigate the relation between myopia and variations in three genes coding for matrix metalloproteinases, enzymes that degrade matrix proteins and modulate scleral extensibility. METHODS. Three hundred sixty-six men and women, from Sheffield, United Kingdom, were genotyped for the 1G/2G polymorphism in the MMP-1 gene, the 5A/6A polymorphism in the MMP-3 gene and the ArgGln polymorphism in exon 6 of the MMP-9 gene and assessed for refractive error. RESULTS. Risk of myopia was increased in people homozygous for the 5A allele of the MMP-3 gene (odds ratio [OR], 3.1; 95% confidence interval [CI], 1.1–9.0) compared to those who were homozygous for the 6A allele, and in people homozygous for the Gln allele in exon 6 of the MMP-9 gene (OR, 2.8; 95% CI, 1.1–7.0) compared to those who were homozygous for the Arg allele. People who were homozygous for the 2G allele of the MMP-1 gene had an odds ratio for myopia of 2.3 (95% CI, 0.9–6.1), compared with those who were homozygous for the 1G allele, although this relation did not reach statistical significance. Risk of myopia increased progressively with the dose of these three alleles, showing a greater than 10-fold difference across the range
Relation between size at birth and age-related cataract
No full textPURPOSE. To determine whether poor fetal growth, as determined by size at birth, is associated with an increased risk of age-related cataract. METHODS. A total of 741 men and women born in Sheffield, England between 1922 and 1930 and whose size at birth was available were traced and invited to take part in the study. Of these, 392 (53%) attended for ophthalmic examination. Lens opacity in these volunteers was graded using the Lens Opacities Classification System (LOCS) III. RESULTS. After adjusting for age, gender, gestational age, and risk factors for cataract there were no consistent associations between size at birth and age-related cataract. However, the odds ratio for nuclear cataract (opalescence) among subjects whose birth weight was more than 8 lb was 2.4 (95% CI 1.2 to 5.0) compared with those who weighed under 6 lb 12 oz at birth. Risk of cortical cataract by contrast fell with increasing birth weight, but the trend was not significant and became weak after adjusting for gestational age and other risk factors for cataract. No relation was evident between risk of posterior subcapsular cataract and size at birth. CONCLUSIONS. There is no consistent association between size at birth and age-related cataract. The higher risk of nuclear cataract with increased birth weight was contrary to the expected trend. The apparent difference in direction of the relation between birth weight and different subtypes of cataract may be a chance finding but warrants further exploration. <br/
Size at birth and carotid atherosclerosis in later life
No full textSeveral studies have shown that low birthweight is associated with a higher risk of stroke and coronary heart disease in later life. Increased atherogenesis may be one underlying mechanism, but few studies have examined this directly. We used duplex ultrasonography to assess the extra-cranial carotid arteries of 389 elderly men and women born and still living in Sheffield, UK, whose recorded birth measurements were available. Men and women who had weighed 6.5 lbs or less at birth had a higher risk of having carotid stenosis >30% than those who weighed over 7.5 lbs, but this trend was not statistically significant (OR 1.8, 95% CI 1.0–3.3). Women who had been lighter or who had a smaller head circumference at birth tended to have an increased intima-media thickness, but these relations ceased to be statistically significant after adjustment for gestational age and cardiovascular risk factors. In men, by contrast, an increased intima-media thickness was associated with having been heavier at birth (P=0.049) or having had a larger abdominal circumference at birth (P=0.040), after adjustment for gestational age and cardiovascular risk factors. These results provide little evidence that impaired fetal growth increases susceptibility to atherogenesis
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
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