Biomedical subjects

J M Seddon

Publications and source records attributed to J M Seddon.

At least 73 records · Page 4Linked to original sources

PubMed1994

The use of vitamin supplements and the risk of cataract among US male physicians.

OBJECTIVES: The purpose of this study was to examine prospectively the association between reported use of vitamin supplements and risk of cataract and cataract extraction. METHODS: The study population consisted of 17,744 participants in the Physicians' Health Study, a randomized trial of aspirin therapy and beta-carotene among US male physicians 40 to 84 years of age in 1982 who did not report cataract at baseline and provided complete information about vitamin supplementation and other risk factors for cataract. Self-reports of cataract and cataract extraction were confirmed by medical record review. RESULTS: During 60 months of follow-up, there were 370 incident cataracts and 109 cataract extractions. In comparison with physicians who did not use any supplements, those who took only multivitamins had a relative risk of cataract of 0.73 after adjustment for other risk factors. For cataract extraction, the corresponding relative risk was 0.79. Use of vitamin C and/or E supplements alone was not associated with a reduced risk of cataract, but the size of this subgroup was small. CONCLUSIONS: These data suggest that men who took multivitamin supplements tended to experience a decreased risk of cataract and support the need for rigorous testing of this hypothesis in large-scale randomized trials in men and women.

Adult↗

PubMed1994

Confirmation of self-reported cataract in the Physicians' Health Study.

Large-scale prospective studies of disease development often rely on self-reported data. To assess the accuracy of self-reports of cataract, we compared the self-reports with medical record data obtained from diagnosing ophthalmologists and optometrists for participants in the Physicians' Health Study, a randomized trial of aspirin and beta-carotene among 22,071 male U.S. physicians aged 40-84 years. A report of cataract, defined as a positive response to a question about whether cataract had ever been diagnosed in either eye and the date of diagnosis, was found to be a very good indicator of lens opacification but was not a good indicator of an incident, age-related opacity that reduced visual acuity. These results indicate that in large prospective studies of clinically significant cataract, where examination of all study participants is not feasible and self-reported data are used, additional documentation to supplement the self-reports should be obtained and strict diagnostic criteria applied to minimize the likely effects of misclassification.

Adult↗

PubMed1994

Reproducibility of a food frequency questionnaire for use in ocular research. Eye Disease Case-Control Study Group.

PURPOSE: Assessment of nutritional factors was an ancillary component of the Eye Disease Case-Control Study sponsored by the National Eye Institute. This multicenter study was designed to evaluate the role of potential risk factors for a number of retinal disorders. The authors examined the reproducibility of the food frequency questionnaire used in this study. METHODS: A semiquantitative food frequency questionnaire, designed for use in this study, was self-administered by participants. To evaluate the reproducibility of this dietary questionnaire, a subsample of 325 participants completed a second questionnaire within 12 to 18 months of the first. Pearson product-moment coefficient was used to assess the correlation between the log of calorie-adjusted nutrient scores, and Spearman correlations were used for specific food items. RESULTS: The responses for intake of 60 food items in the questionnaire were reasonably consistent. Correlation coefficients for individual food items ranged from 0.40 to 0.82. Pearson correlation coefficients for logs of calorie-adjusted intake of nutrients ranged from 0.38 to 0.75. Nutrients of interest in eye disease include total protein (r = 0.57), total fat (r = 0.71), saturated fats (r = 0.69), carotene (r = 0.61), vitamin C (with supplements, r = 0.66), vitamin E (with supplements, r = 0.69), and zinc (with supplements, r = 0.43). Partial correlations controlling for age, sex, and clinical center were similar. CONCLUSIONS: These findings indicate that the food frequency questionnaire used in this study provides reasonably reproducible dietary information.

Adult↗

PubMed1993

A prospective study of aspirin use and cataract extraction in women.

We examined the association between aspirin use and the rates of cataract extraction during 8 years of follow-up in a large prospective study of women, the Nurses' Health Study. From 1980 to 1988, we documented 448 senile cataracts diagnosed and extracted during 434,680 person-years of follow-up. While we observed a modest positive association at the higher doses of aspirin use in the age-adjusted analyses, no association was found after accounting for other cataract risk factors (relative risk for > or = 20 years of use, 1.08; 95% confidence interval, 0.84 to 1.39). Among women who consumed seven or more tablets per week for 20 or more years, there was no suggestion of protection; if anything, a nonsignificantly elevated risk was observed (relative risk, 1.31; 95% confidence interval, 0.94 to 1.80). We observed no consistent difference in the relationship between aspirin use and cataract when assessed by age. Overall, we found no evidence to support the substantial reduction in risk of cataract among aspirin users as reported in several previous studies.

Age Factors↗

PubMed1993

Asymmetric distribution of arteriovenous crossings in the normal retina.

BACKGROUND: Recently, there has been renewed interest in the orientation of the crossing retinal vessels at arteriovenous intersections, particularly as it relates to the risk of branch vein occlusion. Little is known about the distribution of the two types of crossings in the normal retina. METHODS: The authors studied standard fundus photographs of 51 subjects without retinal disease. Arteriovenous crossings were analyzed for fundus location and relative orientation of the crossing vessels (vein-posterior or vein-anterior). FINDINGS: In the superotemporal quadrant, crossings were distributed closer to the optic disc (P < 0.001), and a greater proportion of crossings were vein-posterior (P = 0.01) than in the inferotemporal quadrant. As a result, within a 3-disc diameter (DD) radius of the optic disc, there were significantly more vein-posterior crossings in the superotemporal than in the inferotemporal quadrant (P < 0.001). CONCLUSION: These findings further define normal retinal vascular anatomy and may explain the predilection for branch retinal vein occlusions to occur in the superotemporal quadrant.

Adult↗

PubMed1993

The time course of irradiation changes in proton beam-treated uveal melanomas.

BACKGROUND: Although histopathologic changes in uveal melanomas treated by irradiation have been well characterized, the timing of these effects after irradiation has not been previously evaluated. METHODS: The series consisted of a total of 92 eyes with uveal melanoma, enucleated at various intervals after proton irradiation (range, 1 month to 8 years) due to complications (n = 66) or tumor growth (n = 22), or at autopsy (n = 4). Study slides were read, using a standard protocol, by two pathologists masked to the timing of the enucleation after irradiation and the reason for the surgery. RESULTS: The prevalence of inflammation decreased whereas fibrosis increased with time from 15% of cases enucleated within 12 months (early cases) to 61% of those enucleated more than 30 months (late cases) after irradiation (P for trend = 0.0005). Tumor necrosis and blood vessel damage occurred early, and the prevalence of these changes was constant over time. Excluding tumors with evidence of growth after irradiation, mitotic figures became progressively less common as the interval between irradiation and enucleation increased (P for trend = 0.015); no mitotic figures were present in 40 high-power fields more than 30 months after irradiation. CONCLUSION: Histopathologic changes in irradiated melanomas vary according to the time elapsed since irradiation. Inflammation decreases with time whereas fibrosis becomes more prevalent with time after irradiation. Among controlled tumors, mitotic figures appear only in recently irradiated tumors.

Adult↗

PubMed1993

An evaluation of the influence of reproductive factors on the risk of metastases from uveal melanoma.

BACKGROUND: There is a paucity of data concerning the possible role played by hormonal factors in the risk of metastases from intraocular melanomas. METHODS: The authors studied the influence of post-diagnosis pregnancy and oral contraceptive use in a group of women of reproductive age (45 or younger) who were treated for uveal melanoma by proton beam irradiation. A baseline reproductive history had been collected before irradiation for all women, and interim reproductive data were collected by mailed questionnaire. RESULTS: In this age group, the overall rate of metastasis among women was similar to that of men treated during the same interval (adjusted rate ratio: 1.28; 95% confidence interval: 0.62-2.67). A total of 24 full-term pregnancies were reported among the 139 women still menstruating at diagnosis. Twenty-three women reported regular oral contraceptive use. Metastases developed in 15 of the 139 women. Compared with other women in the series, rates of metastases were not higher among the women who reported pregnancies (P = 0.932) or oral contraceptive use (P = 0.424) after diagnosis. CONCLUSION: Although based on limited numbers, results suggest that the hormonal environment has no appreciable influence on risk of metastases in younger women with uveal melanoma.

Adolescent↗

PubMed1993

Correlates of cognitive function scores in elderly outpatients.

OBJECTIVE: To determine medical, ophthalmologic, and demographic predictors of cognitive function scores as measured by the Telephone Interview for Cognitive Status (TICS), an adaptation of the Folstein Mini-Mental Status Exam. A secondary objective was to perform an item-by-item analysis of the TICS scores to determine which items correlated most highly with the overall scores. DESIGN: Cross-sectional cohort study. SETTING: The Glaucoma Consultation Service of the Massachusetts Eye and Ear Infirmary. SUBJECTS: 472 of 565 consecutive patients age 65 and older who were seen at the Glaucoma Consultation Service between November 1, 1987 and October 31, 1988. MEASUREMENTS: Each subject had a standard visual examination and review of medical history at entry, followed by a telephone interview that collected information on demographic characteristics, cognitive status, health status, accidents, falls, symptoms of depression, and alcohol intake. RESULTS: A multivariate linear regression model of correlates of TICS score found the strongest correlates to be education, age, occupation, and the presence of depressive symptoms. The only significant ocular condition that correlated with lower TICS score was the presence of surgical aphakia (model R2 = .46). Forty-six percent (216/472) of patients fell below the established definition of normal on the mental status scale. In a logistic regression analysis, the strongest correlates of an abnormal cognitive function score were age, diabetes, educational status, and occupational status. An item analysis using step-wise linear regression showed that 85 percent of the variance in the TICS score was explained by the ability to perform serial sevens and to repeat 10 items immediately after hearing them. Educational status correlated most highly with both of these items (Kendall Tau R = .43 and Kendall Tau R = .30, respectively). CONCLUSION: Education, occupation, depression, and age were the strongest correlates of the score on this new screening test for assessing cognitive status. These factors were stronger correlates of the TICS score than chronic medical conditions, visual loss, or medications. The Telephone Interview for Cognitive Status is a useful instrument, but it may overestimate the prevalence of dementia in studies with a high prevalence of persons with less than a high school education.

Accidental Falls↗

PubMed1992

Occupation and risk of uveal melanoma. An exploratory study.

BACKGROUND: Little is known about the cause of uveal melanoma, the most common primary intraocular malignant lesion in adults. This population-based case-control study evaluated occupational exposures. METHODS: One hundred ninety-seven newly diagnosed cases of uveal melanoma participated. Approximately two control subjects matched for age, sex, and telephone exchange area were selected for each case by random-digit dialing. Data were collected by a structured telephone interview. Two systems of occupational coding were used: an occupation-exposure linkage system and the Bureau of Census data. Conditional logistic regression for matched studies was used to examine various occupational exposures while controlling for previously reported potential confounders and for family income. The occupation-exposure matrix was used to define clusters of cases exposed to a particular chemical group from various occupations. RESULTS: Odds ratios were elevated for agriculture and farming work for both industry and occupation; this was consistent across both classification systems. Elevated odds ratios also were found for occupations involving machine operations, fabrication, assembling, equipment cleaning, and exposure to metal industries. Exposure to alkylating agents and phenols was associated with a lower risk compared with all other exposures. Several self-reported exposures also were studied. Exposures associated with elevated odds ratios were inks, insecticides, gases, radioactive substances, polybromated biphenyls, and chemical solvents. CONCLUSIONS: This exploratory study suggests various occupational associations for uveal melanoma and areas for future research.

Adolescent↗

PubMed1992

A prospective study of cigarette smoking and risk of cataract in men.

OBJECTIVE: To examine the association between cigarette smoking and the incidence of cataract. DESIGN, SETTING, AND PARTICIPANTS: The design was a prospective cohort study using data from the Physicians' Health Study, a randomized trial of aspirin and beta carotene among 22,071 US male physicians aged 40 to 84 years that began in 1982. This analysis includes the 17,824 physicians who did not report cataract at baseline and did provide complete risk factor information. Based on information reported at baseline, 10% were current smokers, 39% were past smokers, and 51% were never smokers. MAIN OUTCOME MEASURE: An incident cataract was defined as a self-report confirmed by medical record review to have been first diagnosed after randomization, age-related in origin, and responsible for a decrease in best corrected visual acuity to 20/30 or worse. MAIN RESULTS: During 60 months of follow-up, 557 incident cataracts among 371 participants were confirmed. Compared with never smokers, current smokers of 20 or more cigarettes per day had a statistically significant increase in the risk of cataract (relative risk [RR], 2.16; 95% confidence interval [Cl], 1.46 to 3.20; P less than .001). Similar results were obtained after simultaneously controlling for other potential cataract risk factors in a logistic regression model (RR, 2.05; 95% Cl, 1.38 to 3.05; P less than .001). Among the 557 eyes with cataract, nuclear sclerotic changes were present in 442 while posterior subcapsular changes were present in 204. After controlling for other potential cataract risk factors, current smokers of 20 or more cigarettes per day had statistically significant increases in nuclear sclerosis (RR, 2.24; 95% Cl, 1.47 to 3.41; P less than .001) and posterior subcapsular (RR, 3.17; 95% Cl, 1.81 to 5.53; P less than .001) cataract. Past smokers had an elevated risk of posterior subcapsular (RR, 1.44; 95% Cl, 0.97 to 2.13; P = .07) but not nuclear sclerosis cataract. For current smokers of fewer than 20 cigarettes per day, no increased risks were observed of total, nuclear sclerosis, or posterior subcapsular cataract. CONCLUSIONS: These data provide support for the hypothesis that cigarette smoking increases the risk of developing both nuclear sclerosis and posterior subcapsular cataract.

Adult↗

PubMed1992

A prospective study of cigarette smoking and risk of cataract surgery in women.

OBJECTIVE: To examine prospectively the association between cigarette smoking and the risk of cataract extraction in women. DESIGN: Prospective cohort study beginning in 1980 with 8 years of follow-up. SETTING: United States, multistate. PARTICIPANTS: Registered nurses 45 to 67 years of age and free of diagnosed cancer. There were 50,828 women included in 1980 and others were added as they became 45 years of age. MAIN OUTCOME MEASURE: Incidence of senile cataract extraction. RESULTS: We documented 493 incident senile cataracts diagnosed and extracted during 470,302 person-years of follow-up. The age-adjusted relative risk (RR) among women who smoked at least 65 pack-years was 1.63 (95% confidence interval [Cl], 1.18 to 2.26; P for trend, .02). A similar increase in RR was noted when smoking was assessed in terms of number of cigarettes currently smoked or number of cigarettes smoked by past smokers. Results were also similar after adjusting for other potential risk factors for cataract. Smoking was also strongly associated with posterior subcapsular cataract specifically (RR, 2.59; 95% Cl, 1.49 to 4.50 for greater than or equal to 65-pack-year smokers relative to nonsmokers. CONCLUSION: Smoking appears to increase the risk of cataract extraction.

Aged↗

PubMed1992

Nutrient intake and cataract extraction in women: a prospective study.

OBJECTIVE: To examine prospectively the association between dietary intake of vitamins C and E, carotene, and riboflavin and cataract extraction in women. DESIGN: Prospective cohort study beginning in 1980 with eight years of follow up. SETTING: 11 states of the United States. PARTICIPANTS: Female registered nurses who were 45 to 67 years of age. 50,828 women were included in 1980 and others were added as they became 45 years of age. MAIN OUTCOME MEASURE: Incidence of extraction of senile cataracts. RESULTS: 493 cataracts were extracted during 470,302 person years of follow up. Intake of carotene and vitamin A was inversely associated with cataract: in multivariate analyses, women in the highest fifth of total vitamin A intake (excluding supplements) had a 39% lower risk of cataract relative to women in the lowest fifth (relative risk 0.61; 95% confidence interval 0.45 to 0.81). Neither riboflavin nor dietary vitamins E or C were associated with cataract in a multivariate analysis. Among specific food items spinach (rather than carrots, the greatest source of beta carotene) was most consistently associated with a lower relative risk. The risk of cataract was 45% lower among women who used vitamin C supplements for 10 or more years(relative risk 0.55 (0.32 to 0.96)), but no association was noted for multivitamin intake. CONCLUSION: Dietary carotenoids, although not necessarily beta carotene, and long term vitamin C supplementation may decrease the risk of cataracts severe enough to require extraction.

Aged↗

PubMed1992

Lipid polymorphism: a correction. The structure of the cubic phase of extinction symbol Fd-- consists of two types of disjointed reverse micelles embedded in a three-dimensional hydrocarbon matrix.

The X-ray scattering study of a cubic phase of extinction symbol Fd--, recently performed on a lipid extract (PFL) from Pseudomonas fluorescens [Mariani et al. (1990) Biochemistry 29, 6799-6810] has been extended to several other systems, all consisting of mixtures of water-miscible (MO, PC, PE, oleate) and of water-immiscible (FA, DG) lipids, plus water. In all of these systems the cubic phase was observed in the presence of excess water. Some inconsistencies observed between PFL and the other systems, the fact that in PFL one of the reflections of the cubic phase happened to coincide with the strongest reflection of the hexagonal phase, and the finding, in one of the original cubic samples of PFL kept in the cold for more than 3 years, that the intensity of one of the reflections had decreased dramatically all indicated that a nonnegligible amount of a hexagonal impurity was in fact present in the samples of PFL originally thought to contain a pure cubic phase. The intensities were corrected for that impurity and analyzed again using a pattern recognition approach based upon the axiom that the histogram of the electron density maps is invariant with respect to physical structure, when different phases are compared whose chemical composition is the same. The hexagonal phase provided the reference phase for the comparison. The moments mean value of (delta rho)n were used to compare the histograms.(ABSTRACT TRUNCATED AT 250 WORDS)

Crystallography↗

PubMed1992

Cataract extraction after proton beam irradiation for malignant melanoma of the eye.

We evaluated visual outcome and risk of metastases in patients who underwent cataract extraction after protonbeam irradiation of a uveal melanoma. A total of 84 patients underwent cataract extraction between 2 months and 11 years after irradiation. One year after cataract extraction, approximately half of the patients had visual acuity of 20/100 or better, and approximately one third had an acuity of 20/40 or better. Larger tumor size was highly correlated with poor visual outcome 1 year after extraction. Six patients underwent enucleation after cataract removal, five due to blind, painful eyes and one due to continued growth of a previously undiagnosed ring melanoma. The rate of metastases was not higher among patients who underwent cataract extraction (adjusted rate ratio, 0.83). Results suggest that cataract extraction offers improvement of vision in selected eyes previously irradiated for a uveal melanoma, without adding to the risk of metastases among patients undergoing the procedure.

Adult↗

PubMed1992

Histopathology of proton beam-irradiated vs enucleated uveal melanomas.

The histopathology of eyes with uveal melanoma was compared in a masked fashion in 47 eyes whose primary treatment was enucleation and a matched series of 47 eyes enucleated after proton beam irradiation. Irradiated tumors were more likely to show signs of necrosis (P less than .001) and fibrosis (P = .005) and to have balloon cells present (P = .002). In the irradiated group, mitotic figures were fewer in 40 high-power fields (P = .020), and the prevalence of tumor blood vessel damage (P less than .001) was higher. Changes in the retina were more common in the irradiated series, but damage was usually overlying or in close proximity to the tumor. Based on characteristic changes, the pathologist distinguished irradiated from nonirradiated eyes in 85% of the cases. These findings suggest that irradiation damages tumor cells and blood vessels, and alters the tumor's capacity for cellular reproduction.

Adult↗

PubMed1992

Radiation maculopathy after proton beam irradiation for choroidal melanoma.

PURPOSE: Radiation maculopathy is a microangiopathy of the retina, which is often observed after irradiation of the eye. To quantitatively determine the frequency of anatomic and functional features of this condition, the authors reviewed a large series of patients with choroidal melanomas who were treated by proton beam irradiation. METHODS: Color photographs and/or fluorescein angiograms of 218 patients with paramacular choroidal melanomas were graded by two independent masked readers to determine the frequency of the various lesions of radiation maculopathy. RESULTS: Overall, 194 (89%) of the 218 patients in this study developed some degree of radiation maculopathy. The earliest and most common finding was macular edema, which was observed in 87% of patients, overall, by the end of year 3. Microvascular changes (microaneurysms and/or telangiectasia), intraretinal hemorrhages, and capillary nonperfusion were noted in 76%, 70%, and 64% of eyes, respectively, by the end of postirradiation year 3. Visual acuity was retained at 20/200 or better in 90% of eyes 1 year after irradiation and in 67% of eyes 3 years after treatment. CONCLUSION: Radiation maculopathy is common after proton beam irradiation of paramacular choroidal melanomas. However, ambulatory vision is preserved in many eyes.

Adolescent↗

PubMed1992

Intraocular recurrence of uveal melanoma after proton beam irradiation.

The authors evaluated tumor recurrence as an end point in 1077 uveal melanoma patients treated by proton beam irradiation between 1975 and 1987, with a mean follow-up of 4.0 years. Twenty tumors (1.9%) exhibited definitive growth between 4 months and 66 months after irradiation (median, 19 months): 10 were marginal recurrences, 5 were ring melanomas, 3 were uncontrolled tumors, and 2 were extrascleral extensions. Ten of these eyes were enucleated without further intervention, 2 patients died of metastases soon after the growth was detected, and 8 patients had further conservative therapy. In 5 other patients, tumor growth was suspected but unconfirmed and the eye was enucleated elsewhere; the 5-year probability of local tumor control based on 25 recurrences was 97% +/- 1%. There was a nonsignificant increase in the rate of metastases among patients with documented tumor recurrence (adjusted relative risk, 1.5; 95% confidence interval, 0.66 to 3.4). Results suggest that recurrence of uveal melanomas treated by proton beam therapy is uncommon, but that treatment failure may increase risk of death from metastasis.

Adolescent↗

PubMed1992

Smoking and the risk of early metastases from uveal melanoma.

Smoking is suspected of altering host immunity and may therefore hasten the development of metastases among cancer patients. The authors followed 946 patients with melanomas of the choroid and/or ciliary body who had been treated with proton beam irradiation and who had provided a smoking history during their evaluation before treatment. After a mean follow-up of 33 months, 98 patients were diagnosed with metastatic disease. Metastasis-free survival rates 3 years after irradiation were similar in association with never, past, and current cigarette smoking (86%, 89%, and 90%, respectively; P = 0.90). Rates also were similar with increasing pack-years of exposure and when the product smoked was cigarettes versus pipes or cigars only. Estimates for smoking effects were unchanged after adjusting for established prognostic factors for metastases. Results suggest that smoking does not alter the risk of metastases during the first few years after irradiation of choroidal melanomas.

Adolescent↗