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Biomedical subjects

Wayne Smith

Publications and source records attributed to Wayne Smith.

45 records · Page 3Linked to original sources
PubMed2003

Chlorinated drinking water and micronuclei in urinary bladder epithelial cells.

BACKGROUND: Evidence for a causal relationship between disinfection byproducts in chlorinated water and cancer is not conclusive. This study investigates the association between disinfection byproducts in chlorinated water, as measured by trihalomethane concentration, and the frequency of micronuclei in urinary bladder epithelial cells, thereby assessing the carcinogenic potential of disinfection byproducts. METHODS: A cohort study was undertaken in 1997 in 3 Australian communities with varying levels of disinfection byproducts in the water supply. Exposure was assessed using both available dose (total trihalomethane concentration in the water supply) and intake dose (calculated by adjusting for individual variations in ingestion, inhalation, and dermal absorption). Micronuclei in urinary bladder epithelial cells were used as a preclinical biomarker of genotoxicity. RESULTS: Cells were scored for micronuclei for 228 participants, of whom 63% were exposed to disinfection by products and 37% were unexposed. Available dose of total trihalomethane for the exposed group ranged from 38 to 157 micro ;g/L, whereas intake dose ranged from 3 to 469 micro g/kg per day. Relative risk for DNA damage to bladder cells, per 10 micro g/L of available dose total trihalomethane, was 1.01 (95% confidence interval [CI] = 0.97-1.06) for smokers and 0.996 (CI = 0.961-1.032) for nonsmokers. Relative risk, per 10 micro g/kg per day of intake dose of total trihalomethane, was 0.99 (CI = 0.96-1.03) for smokers and 1.003 (CI = 0.984-1.023) for nonsmokers. CONCLUSION: This study provides no evidence that trihalomethane concentrations, at the levels we investigated, are associated with DNA damage to bladder cells.

Adult↗
PubMed2003

Computer simulation of introductory neurophysiology.

A computer-assisted learning (CAL) package, NeuroLab, developed for use by first-year university students undertaking professional programs in the health area, is described and evaluated. NeuroLab is a simulation of a laboratory, in which students are able to impale neurons to measure resting membrane potentials and subsequently undertake experiments including measuring resting membrane potentials, determining threshold potentials, measuring refractory periods, and examining effects on membrane potential through altering the membrane permeability to sodium and potassium ions. Students find the package to be a worthwhile learning experience, with 81 +/- 2.2% reporting the package increased their understanding of neuron function, and 78 +/- 2.5% expressing a desire for more CAL packages. Exposure to the package resulted in significantly higher mean scores in a multiple-choice question test on measuring neuron membrane potentials compared with those who were not exposed (mean scores out of 4 of 2.42 and 2.02, respectively, P < 0.001).

Clinical Laboratory Techniques↗
PubMed2002

Smoking and the 5-year incidence of age-related maculopathy: the Blue Mountains Eye Study.

OBJECTIVE: To assess the relationship between baseline smoking and the 5-year incidence of late and early age-related maculopathy (ARM) in an older population cohort. METHODS: The Blue Mountains Eye Study examined 3654 participants aged 49 years or older during 1992 to 1994 and then 2335 survivors (75.1%) after 5 years. Retinal photographs were graded using the Wisconsin Age-Related Maculopathy Grading System. Those with any ARM lesions at either examination were regraded in detail using a side-by-side method similar to that developed for the Beaver Dam Eye Study. We also used similar definitions for incident ARM lesions. Smoking status was recorded at interview. RESULTS: Age-standardized incidence rates for any late ARM lesions were 3.1%, 1.2%, and 1.4%, respectively, among baseline current, past, or never smokers. Corresponding age-standardized incidence rates for early ARM were 10.6%, 8.2%, and 9.3%, respectively. The mean age for cases with incident late ARM was 67 years for baseline current smokers, 73 years for past smokers, and 77 years for those who had never smoked (P =.02). After adjusting for age, current smokers, compared with never smokers, had an increased risk of incident geographic atrophy (age-adjusted relative risk [RR], 3.6; 95% confidence interval [CI], 1.1-11.3) and any late ARM lesions (RR, 2.5; 95% CI, 1.0-6.2). Current smokers had an increased risk of incident retinal pigmentary abnormalities (RR, 1.7; 95% CI, 1.1-2.7), with the risk higher in men (RR, 2.8; 95% CI, 1.4-5.6). OUTCOME MEASURES: Five-year incidence of early ARM, late ARM, and ARM lesions. CONCLUSIONS: In this cohort, persons who were current smokers had an increased risk of 5-year incident late ARM lesions and retinal pigmentary abnormalities. Current smokers developed late ARM at a significantly earlier age than never or past smokers.

Aged↗
PubMed2002

Five-year incidence of age-related maculopathy lesions: the Blue Mountains Eye Study.

PURPOSE: To describe the 5-year incidence and progression of early and late age-related maculopathy (ARM) lesions. DESIGN: Population-based cohort study. PARTICIPANTS: Three thousand six hundred fifty-four noninstitutionalized residents, aged 49 years or older, living in the Blue Mountains area west of Sydney, Australia, participated in the study during 1992 to 1994. The cohort was reexamined after 5 years (1997-1999). Excluding 543 participants who died since the baseline, 2335 (75%) survivors attended 5-year follow-up examinations. METHODS: Retinal photographs from both examinations were graded using the Wisconsin ARM Grading System. Photographs of participants with any ARM lesions at either examination were regraded in detail using a modification of the side-by-side method developed for the Beaver Dam Eye Study. MAIN OUTCOME MEASURES: Incidence and progression of ARM lesions were defined in a similar manner to that used in the Beaver Dam Eye Study. RESULTS: Incidence rates for all ARM lesions increased significantly with age. For late ARM lesions (geographic atrophy and neovascular ARM), the overall 5-year incidence was 1.1%. The combined late ARM incidence was 0.0%, 0.6%, 2.4%, and 5.4% for participants aged 60 years and younger, 60 to 69 years, 70 to 79 years, and 80 years and older at baseline, respectively. After excluding participants with either early or late ARM in either eye at baseline, the overall 5-year incidence of early ARM was 8.7%, including 3.2%, 7.4%, 18.3%, and 14.8% for the corresponding age groups. The incidence of neovascular ARM in women was double that for men (P = 0.1). CONCLUSIONS: This study has documented the incidence of ARM lesions in an older Australian population. The slightly higher incidence of hyperpigmentation found in our population compared with the Beaver Dam Eye Study may be due to sample variability, or this could reflect real differences between the two populations. Our lower incidence of soft drusen could have resulted from our non-inclusion of intermediate soft drusen in the soft distinct and indistinct drusen categories.

Age Distribution↗
PubMed2002

Dietary antioxidant intake and incidence of early age-related maculopathy: the Blue Mountains Eye Study.

OBJECTIVE: To investigate associations between dietary intake, including modest supplement intake, of antioxidant vitamins and zinc at baseline and the 5-year incidence of early age-related maculopathy (ARM). DESIGN: Population-based cohort study. PARTICIPANTS: From 1992 through 1994, 3654 persons aged 49 years or more (82% of those eligible) living in two postcode areas west of Sydney, Australia, were examined for the Blue Mountains Eye Study baseline. Five years later, 2335 persons (75% of known survivors) were reexamined. METHODS: A 145-item Food Frequency Questionnaire (FFQ) was used to assess nutrient intakes. Of the 2335 people who attended a follow-up visit, 1989 (85%) had completed a FFQ at baseline. The nutrients examined in this study included: alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein and zeaxanthin, lycopene, retinol, vitamin A, vitamin C, and zinc. MAIN OUTCOME MEASURES: Early ARM was assessed by masked grading of stereo retinal photographs. Definitions for incidence closely followed those used in the Beaver Dam Eye Study. RESULTS: Early ARM developed in 192 persons (8.7% 5-year incidence) who did not have either late or early ARM at baseline. Of these, 159 persons completed the FFQ at baseline. After adjusting for age, gender, family history of ARM, and smoking status at baseline, no associations, or any trends suggesting possible association, were found between baseline intake of the nutrients examined, apart from vitamin C, and the 5-year incidence of early ARM. Compared with the lowest quintile, increasing baseline intakes of vitamin C, from diet and supplements, was associated with an increased risk of incident early ARM (odds ratio [OR], 1.7; 95% confidence interval [CI], 1.0-3.0; and OR, 2.3; 95% CI, 1.3-4.0 for the fourth and fifth quintiles, respectively). CONCLUSIONS: Our cohort study of an older population could not find evidence of protection associated with usual dietary antioxidant or zinc intakes (including use of supplements) on the 5-year incidence of early ARM.

Aged↗
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↗
PubMed1998

Regional Neuropeptide Pathology in Alzheimer's Disease: Corticotropin-Releasing Factor and Somatostatin.

BACKGROUND: the neuropeptides most consistently reported to be altered in Alzheimer's disease are corticotropin-releasing factor and somatostatin (somatotropin-release inhibiting factor), although this has been previously assessed in a limited number of brain regions. METHODS: in order to comprehensively characterize the involvement of these two anatomically distinct neuropeptide systems in Alzheimer's disease and to determine if they are equally involved in the associated pathology, we measured the concentration of corticotropin-releasing factor and somatostatin in post-mortem brain tissue. Radioimmunoassay of 24 cortical and 13 sub-cortical brain regions from 16 cases of neuropathologically confirmed AD and 9 non-Alzheimer's disease controls were performed and significant differences in group regional neuropeptide concentrations were sought using the Student Newman-Keuls test after ANOVA. RESULTS: comparison of group mean regional neuropeptide concentrations revealed several brain regions where both peptides were decreased in Alzheimer's disease and some regions where only one of the two peptides were decreased, while still other regions exhibited no changes in either peptide. These changes were principally found in frontal and temporal cortex, with few subcortical regions exhibiting pathologic changes in peptide concentration. Regional peptide content was correlated among peptides and with duration of dementia in several brain regions. CONCLUSIONS: these data support the hypothesis that the somatostatin- and corticotropin-releasing factor containing neurons are pathologically involved in AD and that the involved neurons are limited to specific areas of the brain.

Journal Article↗
PubMed1986

Adolescent sexual offenders: offender and offense characteristics.

Descriptive data are presented on 305 adolescent sexual offenders. Types of offenses and the circumstances under which they occurred are described. Results suggest that adolescents commit an array of sexual offenses, that they are not typically isolated incidents, and that they are frequently indicative of more general adjustment difficulties.

Adolescent↗