Search PubMed⌕ Search

Biomedical subjects

Paul Mitchell

Publications and source records attributed to Paul Mitchell.

190 records · Page 11Linked to original sources
PubMed2002

High heritability of myopia does not preclude rapid changes in prevalence.

The aetiology of myopia is complex, but the major form of myopia results from an interplay between genetic factors and environmental influences. Although there are clear patterns of family inheritance and high heritability values in studies from all over the world,environmental factors are increasingly important in determining myopic outcomes in East Asia, and perhaps elsewhere. This is not paradoxical, as high heritability does not preclude strong environmental influences. The lower heritability values obtained from parent-offspring correlations in populations of East Asian origin where there are marked differences in the environmental exposures (education and urbanization) of parents and children, and where there has been a major shift in the population distribution of myopia, are consistent with this view. Despite the impact of environmental pressures in East Asia, there is evidence that parental myopia influences the position of their offspring within that new population distribution.

Asia↗
PubMed2002

Socioeconomic status and incident cataract surgery: the Blue Mountains Eye Study.

The aim of this study was to assess whether socioeconomic status influenced the incidence of cataract surgery in a defined population of older Australians. The Blue Mountains Eye Study examined 3654 residents during 1992-1994, then 2334 survivors (75.1%)during 1997-1999. Interviewers collected information on principal occupation, which was analysed using Australian Bureau of Statistics categories (stratified into four groups) and the Daniel Occupational Prestige Scale. Cataract surgical history was confirmed at both visits from clinical examinations. There were no statistically significant associations for any of the occupational categories with the 5-year incidence of cataract surgery. In summary, this study could not confirm any major socioeconomic associations with incident cataract surgery, supporting the view that cataract surgery is largely patient driven and that its primary incentive is patient benefit.

Aged↗
PubMed2002

Use of vitamin and zinc supplements and age-related maculopathy: the Blue Mountains Eye Study.

PURPOSE: To investigate relationships between vitamin and zinc supplement use and age-related maculopathy in a population-based sample. METHODS: We studied 2873 (79%) of the 3654 participants aged 49- 97 years who attended the cross-sectional Blue Mountains Eye Study and completed a detailed food frequency questionnaire, including type, dose and duration of supplement use. ARM was assessed during a masked grading of macular photographs. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using logistic regression. RESULTS: After adjusting for multiple confounders, we found that no vitamin or zinc supplements were significantly associated with reduced prevalence of any ARM lesions in either eye. The OR for use of any vitamin supplement was 1.3 (CI 0.9-1.7, p = 0.11) for individuals with any retinal pigment changes. It was 1.1 (CI 0.8-1.5, p = 0.59) for those with any soft (large) drusen and 1.5 (CI 0.7-3.0, p = 0.31) for those with late ARM lesions. The lack of association between supplement intake and ARM persisted regardless of their duration of use, dose or the smoking status of participants. The Breslow-Day test for heterogeneity was 0.24 with an OR for early ARM lesions among smokers of 0.7 (CI 0.4-1.3, p = 0.27), and 1.2 (CI 0.9-1.5, p = 0.24) among non-smokers. CONCLUSION: This cross-sectional population-based study investigated associations between vitamin and zinc supplement use and the prevalence of ARM lesions. Our findings provide no support for a protective association between vitamin and zinc supplement use and lesions indicating early ARM. The small numbers of subjects with late ARM lesions precluded any detailed investigation of benefits from supplement use on the prevalence of these lesions.

Aged↗
PubMed2002

Bias in self-reported family history and relationship to glaucoma: the Blue Mountains Eye Study.

PURPOSE: To examine bias in the relationship between self-reported family history of glaucoma and its relationship to the prevalence of glaucoma and ocular hypertension. METHODS: In a cross-sectional population-based study of 3654 Australians aged 49-97, participants were asked whether any first-degree relatives had been diagnosed with glaucoma. Open-angle glaucoma was diagnosed from matching optic disc and typical visual field changes, after gonioscopy. Ocular hypertension (OH) was diagnosed from elevated intraocular pressure (IOP) in subjects without glaucoma. RESULTS: Glaucoma was present in 3.0% and ocular hypertension in 5.2% of subjects. A parent or sibling was reported to have glaucoma by 8.6%, including 10.5% of women and 5.9% of men. A positive family history was reported more frequently in parents (6.4%) than siblings (2.6%). Glaucoma was reported more frequently to affect mothers (5.0%) and sisters (1.6%) than fathers (1.5%) and brothers (1.2%). A first-degree family history was given by 15.7% of subjects with glaucoma compared to 8.3% of controls, odds ratio (OR) 3.2 (95% CI 1.8-5.6), after adjusting for glaucoma risk factors, including IOP. The association had a similar magnitude for a family history in parents and siblings. Although recall bias was evident from the finding of increased odds (OR 4.2) among previously diagnosed cases, the relationship with family history also persisted in newly-diagnosed cases (OR 2.4). A slightly stronger relationship was found between OH and glaucoma family history, OR 3.9 (95% CI 2.6-5.7), after adjusting for confounders, but was also strongly influenced by recall bias. CONCLUSIONS: Although a positive family history of glaucoma may help to identify those at risk, it is subject to recall, selection and survival bias as well as community under-diagnosis of glaucoma and will most likely substantially underestimate the genetic influence.

Aged↗
PubMed2002

The intake of carotenoids in an older Australian population: The Blue Mountains Eye Study.

OBJECTIVE: To describe the distribution of carotenoid intakes and important food sources of carotenoids in the diet of a representative population of older Australians. DESIGN: Population-based cohort study. SETTING: Two post-code areas in the Blue Mountains, west of Sydney, Australia. SUBJECTS: We studied 2012 (86%) of the 2334 participants aged 55+ years attending the 5-year follow-up of the cross-sectional Blue Mountains Eye Study (BMES), who completed a detailed semi-quantitative food-frequency questionnaire. The intakes for five carotenoids were studied: alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein and zeaxanthin combined, and lycopene. RESULTS: The mean intake per day for each carotenoid was: alpha-carotene, 2675 microg; beta carotene equivalents, 7301 microg; beta-cryptoxanthin, 299 microg; lutein and zeaxanthin, 914 microg; lycopene, 3741 microg; retinol, 653 microg; total vitamin A, 1872 microg retinol equivalents. beta-Carotene equivalents contribute a substantial proportion of total vitamin A intake (65%) in this population. Women had slightly higher intakes than men for alpha-carotene, beta-carotene equivalents, and lutein and zeaxanthin (P < 0.05). Carrots and pumpkin were the main contributors to alpha-carotene and beta-carotene equivalent intakes. Orange juice, oranges and papaw were the main contributors to beta-cryptoxanthin intake. Broccoli, green beans and oranges contributed substantially to lutein and zeaxanthin intake. The main contributors to lycopene intake were tomatoes and bolognaise sauce. CONCLUSIONS: Vitamin A intake in this population is high relative to the Australian Recommended Dietary Intake. Carotenoid intakes, particularly beta-carotene, make a substantial contribution, particularly from fruit and vegetables. This study provides important information as a basis for examining associations between dietary carotenoid intake and eye disease in the BMES.

Carotenoids↗
PubMed2002

Prehospital delay in individuals with acute coronary disease: concordance of medical records and follow-up phone interviews.

Patient-associated delay in seeking medical care in persons with acute coronary disease is receiving increasing importance given the time-dependent benefits associated with myocardial reperfusion therapies. We examined the extent of concordance between self-reported information about prehospital delay provided by patients to hospital staff at the time of hospitalization for coronary disease compared with information obtained from a telephone interview approximately 2 months following hospital discharge. The sample included 316 patients with acute myocardial infarction or unstable angina at 43 hospitals who had delay time information available from both data sources. The extent of agreement between the medical record and telephone accounts of delay was 47% in the total study sample, 53% in patients with acute myocardial infarction, and 40% in patients with unstable angina. These results suggest that a telephone interview carried out several months following hospitalization for acute coronary disease may not provide sufficiently reliable information about prehospital delay.

Aged↗
PubMed2002

Homonymous visual field defects and stroke in an older population.

PURPOSE: The objective of the present study was to describe the prevalence of homonymous visual field defects in a defined older urban population and associations with self-reported stroke. METHODS: Homonymous visual field defects were assessed from screening automated visual field tests of both eyes in 3654 persons aged > or =49 years who were participating in the Blue Mountains Eye Study. This represented 82.4% of eligible residents from a defined area west of Sydney, Australia. A detailed eye examination was performed, and the medical history was taken. Masked grading of visual fields was used to classify the presence of homonymous visual field defects. RESULTS: Homonymous visual field defects were found in 25 persons (prevalence 0.8%, 95% CI 0.5% to 1.1%). Stroke history was reported by 194 participants (5.3%, 95% CI 4.6% to 6.1%). A strong relationship was found between homonymous visual field defects and history of stroke, age-, and sex-adjusted odds ratio (OR) 23.4 (95% CI 9.9 to 55.7). Homonymous field defects were present in 8.3% of all persons who reported experiencing a stroke. Among those with homonymous field defects, 52% reported a history of stroke. Only 2 of 10 persons (20%) with homonymous field defects without a history of stroke reported having stopped driving, whereas 6 of 9 (67%) reporting stroke had stopped driving (P=0.07). Increasing age (OR 1.4 per decade, 95% CI 1.2 to 1.8) was significantly associated with homonymous visual field defects, with adjustment for sex, whereas a history of hypertension (OR 2.7, 95% CI 1.2 to 6.1), diabetes (OR 2.1, 95% CI 1.4 to 3.2), and renal impairment (OR 2.8, 95% CI 1.0 to 8.1) also was associated, with adjustment for age and sex. CONCLUSIONS: This study provides accurate prevalence data for homonymous visual field defects in an older population. About half the participants did not report stroke.

Age Distribution↗
PubMed2002

Myopia and incident cataract and cataract surgery: the blue mountains eye study.

PURPOSE: To assess whether an association exists between myopia and incident cataract and cataract surgery in an older population-based cohort study. METHODS: The Blue Mountains Eye Study examined 3654 participants aged 49 years or more during 1992 to 1994 and then 2334 (75.1%) of the survivors after 5 years. A history of using eyeglasses for clear distance vision was obtained. Objective refraction was performed with an autorefractor, followed by subjective refraction with a logarithm of minimum angle of resolution (logMAR) chart. Emmetropia was defined as a spherical equivalent refraction between +1 D and -1 D, hyperopia as more than +1 D, and myopia as less than -1 D. Slit lamp and retroillumination lens photographs were graded for presence of cortical, nuclear, or posterior subcapsular cataract, according to the Wisconsin Cataract Grading System. Generalized estimating equation models analyzed data by eye. RESULTS: There was a statistically significant association between high myopia (-6 D or less) and incident nuclear cataract (odds ratio [OR] 3.3, 95% confidence interval [CI] 1.5-7.4). Incident posterior subcapsular cataract was associated with any myopia (OR 2.1, 95% CI 1.0-4.8), moderate to high myopia (-3.5 D or less, OR 4.4, 95% CI 1.7-11.5), and use of distance glasses before age 20 (OR 3.0, 95% CI 1.0-9.3), after adjustment for multiple potential confounders, including severity of nuclear opacity. Incident cataract surgery was significantly associated with any myopia (OR 2.1, 95% CI 1.1-4.2) as well as moderate (-3.5 to more than -6D; OR 2.9, 1.2-7.3) and high myopia (OR 3.4, 95% CI 1.0-11.3). CONCLUSIONS: These epidemiologic data provide some evidence of an association between myopia and incident cataract and cataract surgery, after adjustment for multiple confounders and severity of nuclear opacity. These data support other cross-sectional and longitudinal population-based findings.

Aged↗
PubMed2001

Mannan Mucin-1 Peptide Immunization: Influence of Cyclophosphamide and the Route of Injection.

SUMMARY: The mucin MUC1 is greatly increased in breast cancer and is a potential target for immunotherapy. In mice, MUC1 conjugated to oxidized mannan (MUC1-mannan fusion protein [M-FP]) targets the mannose receptor and induces a high frequency of cytotoxic T lymphocytes and anti-tumor responses. On this basis, three phase I trials were performed in patients with adenocarcinoma to evaluate the tnxicity and the immunologic responses to mannan MUC1. Forty-one patients with metastatic or locally advanced carcinoma of the breast (trial 1), colon (trial 2), and various adenocarcinomas (trial 3) received increasing doses of M-FP (1 to 300 &mgr;g). The immunizations were given at weekly intervals (weeks 1 to 3) and repeated in weeks 7 to 9. Cyclophosphamide (to increase cellular immunity) was given on weeks 1 and 4. M-FP was given intramuscularly in trial 1 and intraperitoneally in trial 2. No toxic effects occurred, and delayed-type hypersensitivity responses were present only as a microscopic lymphocytic infiltration. Overall, approximately 60% of the patients had high-titer MUC1 immunoglobulin G1 antibody responses, with the intraperitoneal route yielding approximately 10-fold higher responses. Cellular responses (proliferation, cytotoxic T cells, or CD8 T cells secreting tumor necrosis factor-alpha alphand interferon-gamma in response to MUC1 stimulation in vitro) were found in 28% of the patients, which was similar to that seen without cyclophosphamide. In most patients, disease progressed, but in five it remained stable. In addition, there were no objective responses. M-FP is not toxic and induces immune responses that were amplified by the intraperitoneal route of immunization. Cyclophosphamide was of no benefit.

Journal Article↗