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Biomedical subjects

S A Marion

Publications and source records attributed to S A Marion.

At least 19 recordsLinked to original sources
PubMed2002

Evidence for imprinting on chromosome 16: the effect of uniparental disomy on the outcome of mosaic trisomy 16 pregnancies.

Although a number of infants with maternal uniparental disomy of chromosome 16 (upd(16)mat) have been reported, the evidence for imprinting on chromosome 16 is not yet conclusive. To test the hypothesis that upd(16)mat has a distinct phenotype, which would support the existence of imprinted gene(s) on chromosome 16, statistical analysis was performed on a large series (n = 83) of mosaic trisomy 16 cases with molecular determination of uniparental disomy status. The incidence of upd(16)mat was 40%, which is consistent with the expected one third from random chromosome loss during trisomy rescue (P = 0.262). In pairwise comparisons, upd(16)mat was found to be associated with fetal growth restriction (P = 0.029) and with increased risk of major malformation (RR = 1.43; P = 0.053). Regression modeling showed that the effect of upd(16)mat on fetal/neonatal weight and malformation is independent of the degree of trisomy detected in the fetus. Regression modeling to control for the degree of trisomy detected in the placenta was not possible due to limited sample size. We conclude that upd(16)mat is associated with more severe growth restriction, and possibly, with higher risk of malformation. Our hypothesis is that imprinted gene(s) exist on chromosome 16 and that abnormal expression of these gene(s) in upd(16)mat cells during development results in decreased cell proliferation. Although we do not advocate prenatal testing for upd(16), studies on the long-term outcome of upd(16)mat neonates is necessary for counseling purposes.

Amniocentesis↗
PubMed2002

Occupational and environmental risk factors for Parkinson's disease.

The etiology of Parkinson's disease (PD) remains obscure. Current research suggests that a variety of occupational and environmental risk factors may be linked to PD. This paper provides an overview of major occupational and environmental factors that have been associated with the development of PD and tries to assess current thinking about these factors and their possible mechanisms of operation. While clear links to rural living, dietary factors, exposure to metals, head injury, and exposure to infectious diseases during childhood have not been established, there is general agreement that smoking and exposure to pesticides affect the probability of developing PD.

Environmental Exposure↗
PubMed2001

Influenza revaccination of elderly travelers: antibody response to single influenza vaccination and revaccination at 12 weeks.

The antibody response to a single influenza vaccination and the effect of influenza revaccination was assessed in healthy elderly persons. Travelers > or =65 years old who had received influenza vaccine before travel were enrolled in the study and were offered a second vaccination after 12 weeks. Geographic and age-matched control subjects received a single vaccination. A second influenza vaccination was not associated with increased adverse effects. There was no significant difference between log(10) hemagglutinin-inhibiting (HI) antibody titers or an HI antibody titer > or =1:40 (considered to be protective) in 28 control subjects and 28 revaccinated travelers for any antigen. Probable protection for influenza A antigens remained high 24 weeks after a single immunization and revaccination (A/Sydney/05/97 [H3N2], 92% and 96%, and A/Beijing/262/95 [H1N1], 80% and 96%, respectively). Response to B/Harbin was less throughout the study. A/Sydney antibody titer was lower with more times vaccinated in the previous 5 years. Therefore, a second vaccine did not enhance the immune response.

Aged↗
PubMed2001

Measuring psychosocial job strain with the job content questionnaire using experienced job evaluators.

BACKGROUND: A union/management system of job evaluation has been in place in the British Columbia (BC) sawmill industry since the late 1960s. This system uses an instrument, very similar to the job content questionnaire (JCQ) to evaluate psychosocial work conditions for sawmill jobs. METHODS: Four experienced evaluators, one from the union and three from industry, independently estimated psychosocial work conditions for 54 current job titles in a "typical" coastal sawmill using a shortened, 18-question version of the JCQ questionnaire. RESULTS: Inter-rater reliability was acceptable for control but not for co-worker social support, physical demand, or psychological demand. Reliability was least for psychological demand. CONCLUSIONS: Experienced job evaluators in the sawmill industry were able to reliably estimate only the control dimension of the JCQ. The observed lowest reliability for psychological job demand may be due to the imprecise construct definition in the domain of the JCQ instrument.

Evaluation Studies as Topic↗
PubMed2001

Comparison of expert-rater methods for assessing psychosocial job strain.

OBJECTIVES: This study tested the reliability and validity of industry- and mill-level expert methods for measuring psychosocial work conditions in British Columbia sawmills using the demand-control model. METHODS: In the industry-level method 4 sawmill job evaluators estimated psychosocial work conditions at a generic sawmill. In the mill-level method panels of experienced sawmill workers estimated psychosocial work conditions at 3 sawmills. Scores for psychosocial work conditions were developed using both expert methods and applied to job titles in a sawmill worker database containing self-reported health status and heart disease. The interrater reliability and the concurrent and predictive validity of the expert rater methods were assessed. RESULTS: The interrater reliability and concurrent reliability were higher for the mill-level method than for the industry-level method. For all the psychosocial variables the reliability for the mill-level method was greater than 0.90. The predictive validity results were inconclusive. CONCLUSIONS: The greater reliability and concurrent validity of the mill-level method indicates that panels of experienced workers should be considered as potential experts in future studies measuring psychosocial work conditions.

Adult↗
PubMed2000

Childhood cancer in the offspring of male sawmill workers occupationally exposed to chlorophenate fungicides.

The objective of this study was to determine whether paternal occupational exposure to chlorophenol fungicides and their dioxin contaminants is associated with childhood cancer in the offspring of sawmill workers. We used data from 23,829 British Columbian sawmill workers employed for at least 1 continuous year between 1950 and 1985 in 11 sawmills that used chlorophenates. Probabilistic linkage of the sawmill worker cohort to the provincial marriage and birth files produced an offspring cohort of 19,674 children born at least 1 year after the initiation of employment in the period 1952-1988. We then linked the offspring cohort to the British Columbia Cancer Registry. We included all malignancies in cases younger than 20 years of age that appeared on the cancer registry between 1969 and 1993. We calculated standardized incidence ratios (SIRs) using the British Columbia population as a reference. A nested case-control analysis assessed the effects of paternal cumulative exposure and windows of exposure on the risk of developing cancer in the offspring. We identified 40 cases of cancer during 259,919 person-years of follow-up. The all-cancer SIR was 1.0 [95% confidence interval (CI), 0.7-1.4]; the SIR for leukemia was 1.0 (CI, 0.5-1.8); and the SIR for brain cancer was 1.3 (CI, 0.6-2.5). The nested case-control analysis showed slightly increased risks in the highest categories of chlorophenol exposure, although none was statistically significant. Our analyses provide little evidence to support a relationship between the risk of childhood cancer and paternal occupational exposure to chlorophenate fungicides in British Columbian sawmills.

Adolescent↗
PubMed1999

Examination for sexual assault: is the documentation of physical injury associated with the laying of charges? A retrospective cohort study.

BACKGROUND: Few studies have examined whether there is an association between individual medical findings and legal outcome in cases of sexual assault. This study was undertaken to determine the relation between the extent of documented physical injury and a positive legal outcome in cases of sexual assault and to determine other factors associated with the laying of charges in such cases. METHODS: In this retrospective cohort study, the authors reviewed the charts and medicolegal reports for all cases of sexual assault that were handled by the BC Women's Sexual Assault Service in 1992 for which a police report had been filed. Information on patients' characteristics, the nature of the assault and the extent of injury was extracted from these records. A system for scoring clinical injury was developed by 4 of the physicians at the Sexual Assault Service, and a clinical injury score was assigned for each case by one physician. The relation between the outcome (in terms of whether charges were laid) and the circumstances of the case was examined by logistic regression. RESULTS: A total of 95 cases with complete medical records and information about legal outcome were identified during the 1992 calendar year. After adjustment for income level and the patient's knowledge of the assailant (either as an acquaintance or as his or her partner), the odds ratio (OR) for charge-laying in a sexual assault case with documented moderate to severe injury was 3.33 (95% confidence interval [CI] 1.06-10.42). Socioeconomic status above the group median (defined as annual income greater than $21,893) (OR 3.26, 95% CI 1.09-9.71) and knowledge of the assailant (OR 4.58, 95% CI 1.52-13.79) were also associated with charge-laying. Presence of genital injury per se, age of the patient and detection of sperm by microscopy at the time of examination were not associated with the laying of charges. INTERPRETATION: The results of this study show that the extent of documented injury is associated with the laying of charges in cases of sexual assault. However, many questions remain about the effectiveness of the medical component of gathering such evidence.

Adolescent↗
PubMed1999

Exposures to wood dust in U.S. industries and occupations, 1979 to 1997.

BACKGROUND: We analyzed 1,632 measurements of airborne wood dust reported to OSHA's Integrated Management Information System in the period 1979 to 1997. METHODS: The relationships between wood dust concentrations and various factors documented in the OSHA database were examined in a multiple regression model. RESULTS: Exposures ranged from less than 0.03 to 604 mg/m3, with an arithmetic mean of 7.93 and a geometric mean of 1.86. Reported exposure levels decreased substantially over time (e.g., unadjusted geometric mean in 1979 = 4.59 mg/m3; in 1997 = 0.14 mg/m3). High exposure jobs included sanders in the transportation equipment industry (unadjusted geometric mean = 17.5 mg/m3), press operators in the wood products industry (12.3 mg/m3), lathe operators in the furniture industry (7.46 mg/m3), and sanders in the wood cabinet industry (5.83 mg/m3). CONCLUSIONS: In the multiple regression model, year, state, job, and industry were found to be predictors of exposure. Year and state were likely surrogates for other factors which directly influence exposure, but which were not included in the IMIS database, such as the use of engineering control measures.

Air Pollutants, Occupational↗
PubMed1999

Effectiveness of community-directed diabetes prevention and control in a rural Aboriginal population in British Columbia, Canada.

This report presents the process and summative evaluation results from a community-based diabetes prevention and control project implemented in response to the increasing prevalence and impact of non-insulin-dependent diabetes mellitus (NIDDM) in the Canadian Aboriginal population. The 24-month project targeted the registered Indian population in British Columbia's rural Okanagan region. A participatory approach was used to plan strategies by which diabetes could be addressed in ways acceptable and meaningful to the intervention community. The strategies emphasised a combination of changing behaviours and changing environments. The project was quasi-experimental. A single intervention community was matched to two comparison communities. Workers in the intervention community conducted interviews of individuals with or at risk for diabetes during a seven-month pre-intervention phase (n = 59). Qualitative analyses were conducted to yield strategies for intervention. Implementation began in the eighth month of the project. Trend measurements of diabetes risk factors were obtained for 'high-risk' cohorts (persons with or at familial risk for NIDDM) (n = 105). Cohorts were tracked over a 16-month intervention phase, with measurements at baseline, the midpoint and completion of the study. Cross-sectional population surveys of diabetes risk factors were conducted at baseline and the end of the intervention phase (n = 295). Surveys of community systems were conducted three times. The project yielded few changes in quantifiable outcomes. Activation of the intervention community was insufficient to enable individual and collective change through dissemination of quality interventions for diabetes prevention and control. Theory and previous research were not sufficiently integrated with information from pre-intervention interviews. Interacting with these limitations were the short planning and intervention phases, just 8 and 16 months, respectively. The level of penetration of the interventions mounted was too limited to be effective. Attention to process is warranted and to the feasibility of achieving effects within 24 months.

Adult↗
PubMed1999

Variation by body mass index and age in waist-to-hip ratio associations with glycemic status in an aboriginal population at risk for type 2 diabetes in British Columbia, Canada.

BACKGROUND: It is unclear whether obesity and age modify or confound relations between abdominal adiposity and metabolic risk factors for type 2 diabetes. OBJECTIVE: Our objective was assess the consistency of relations between abdominal adiposity and glycemic variables across discrete categories of obesity and age. DESIGN: We performed a stratified analysis of prevalence data from a rural screening initiative in British Columbia, Canada. Subjects were Salishan Indians, all healthy relatives of individuals with type 2 diabetes [n = 151; age: 18-80 y; body mass index (BMI, in kg/m2): 17.0-48.2]. We measured waist-to-hip ratio (WHR) (2 categories); insulin, glycated hemoglobin (Hb A1c), and 2-h glucose concentrations (2 categories); and BMI (4 categories). BMI and age-specific odds ratios (ORs) and 95% CIs were calculated. RESULTS: WHR-glycemic variable relations were not consistent across BMI and age strata. Risks associated with high WHR were: for persons with BMIs from 25 to 29, elevated insulin (OR: 6.71; 95% CI: 1.41, 34.11) and Hb A1c (OR: 16.23; 95% CI: 2.04, 101.73) concentrations; for persons aged 18-34 y, elevated insulin concentrations [OR: indeterminate (+infinity); 95% CI: 1.89, +infinity]; and, for persons aged 35-49 y, elevated Hb A1c (OR: +infinity; 95% CI: 3.17, +infinity) and 2-h glucose (OR: 9.15; 95% CI: 1.74, 59.91) concentrations. CONCLUSIONS: WHR discriminates risk of type 2 diabetes in overweight but not obese individuals. Abdominal adiposity is associated with elevated insulin concentrations in younger age groups and with impaired glucose control in middle-aged groups, suggesting metabolic staging by age on a continuum from insulin resistance to impaired glucose tolerance.

Adipose Tissue↗
PubMed1999

Mortality rates after cataract extraction.

Senile cataract may be a marker of generalized tissue aging. We examined this hypothesis using population-based linked health data. We hypothesized that any such association would diminish with increased use of cataract surgery. Mortality rates of those 50-95 years of age undergoing cataract surgery in British Columbia during either 1985 or 1989 were compared with the provincial population of comparable age who did not undergo cataract surgery during the study period. The 1985 cohort included 8,262 patients undergoing surgery and a comparison population of 804,303, and the 1989 cohort included 11,952 patients and a comparison population of 839,393. Using Cox regression, for the 1985 cohort, the hazard ratios for dying during follow-up were 3.2 for males 50-54.9 years of age [95% confidence limits (CL) = 2.0, 5.0] and 3.3 for females (95% CL = 1.9, 5.7). Hazard ratios for older age groups decreased with age. We also fit an additive risk model that produced excess mortalities that were less age dependent. In the 1985 analysis, these ranged from +7.1 per 1,000 (95% CL = +0.44, +13.76) to +20.3 (95% CL = +13.24, +27.36) for males and -17.5 (95% CL = -28.28, -6.72) to +2.0 (95% CL = -2.12, +6.12) for females. Findings for the 1989 analyses were similar, indicating that the association between cataracts and generalized aging remained constant despite a large increase in the use of cataract surgery.

Age Distribution↗
PubMed1999

Determinants of exposure to inhalable particulate, wood dust, resin acids, and monoterpenes in a lumber mill environment.

In a lumber mill in the northern inland region of British Columbia, Canada, we measured inhalable particulate, resin acid, and monoterpene exposures, and estimated wood dust exposures. Potential determinants of exposure were documented concurrently, including weather conditions, tree species, wood conditions, jobs, tasks, equipment used, and certain control measures. Over 220 personal samples were taken for each contaminant. Geometric mean concentrations were 0.98 mg/m3 for inhalable particulate, 0.49 mg/m3 for estimated wood dust, 8.04 micrograms/m3 for total resin acids, and 1.11 mg/m3 for total monoterpenes. Multiple regression models for all contaminants indicated that spruce and pine produced higher exposures than alpine fir or mixed tree species, cleaning up sawdust increased exposures, and personnel enclosure was an effective means of reducing exposures. Sawing wood in the primary breakdown areas of the mill was the main contributor to monoterpene exposures, so exposures were highest for the barker operator, the head rig operator, the canter operator, the board edgers, and a roving utility worker in the sawmill, and lowest in the planer mills (after kiln drying of the lumber) and yard. Cleaning up sawdust, planing kiln-dried lumber, and driving mobile equipment in the yard substantially increased exposures to both inhalable particulate and estimated wood dust. Jobs at the front end of the sawmill where primary breakdown of the logs takes place had lower exposures. Resin acid exposures followed a similar pattern, except that yard driving jobs did not increase exposures.

Air Pollutants, Occupational↗
PubMed1998

Models of survival in HIV infection and their use in the quantification of treatment benefits.

Because acquired immunodeficiency syndrome (AIDS) is a shifting endpoint and sufficient follow-up data now allow modeling of survival time (i.e., time from human immunodeficiency virus (HIV) seroconversion to death), the authors evaluated non-parametric and parametric models of mortality with the use of data from 554 seropositive participants in the Vancouver Lymphadenopathy-AIDS Study. The authors then applied these models to quantify treatment benefits at the national level in Canada, using back-calculation and forward-projection based on death registries. The study revealed that the lognormal model better describes survival time than the Weibull model. Relative to observations prior to 1987, later observations (in the era of treatment) revealed a statistically significant change in disease progression: the median survival time increased from 10.1 to 12.0 years, but no further survival improvements were observed in the early 1990s. Concurrent with the increase in availability of treatment, the authors have observed pronounced treatment benefits at the national level: prior to 1995, approximately 1,500 deaths were prevented and 4,200 person-years of life were saved. Also, mortality rates were observed to level off in the mid-1990s due to the shape of the historical HIV infection curve and the accumulating availability of treatment in Canada.

Canada↗
PubMed1998

Socioeconomic factors associated with suicide in elderly populations in British Columbia: an 11-year review.

OBJECTIVE: The effects of socioeconomic factors on suicide rates in the general population are widely documented. Few of these reports have specifically studied the effects of socioeconomic variables on suicide rates in the elderly population. Elderly persons have the highest suicide rates of any age-group. This group is different from the rest of the population insofar as suicide is concerned. For example, since most elderly persons are no longer in the labour force, it would be expected that they would be affected differently by economic factors such as unemployment. We report the findings of an ecological study of old-age suicide in British Columbia over an 11-year period. METHODS: We obtained information on all suicide counts (International Classification of Diseases [ICD-9] codes E590-959) recorded in the 21 health units of British Columbia over the 11-year period from October 1, 1981, to September 30, 1991, from the Division of Vital Statistics of the Province of British Columbia and Statistics Canada. Social, economic, and demographic information for the health units was obtained from census data and included the number of persons per household, proportion of the population that lived in 1-person households, immigration and migration rates for each region, proportion of the population with less than grade 9 education, proportion with less than grade 12 certification, marital status rates, unemployment rates by gender, average household income, average census family income, and labour-force participation rate by gender. We calculated overall and gender-specific suicide rates for elderly persons (65 years and older) and younger populations. Using Poisson regression analyses, we determined the cross-sectional and longitudinal relative risks associated with the socioeconomic variables for the units, and we also examined trends in suicide rates. RESULTS: There were 4630 suicides in the 11-year period. The mean suicide rate (per 100,000 population) for those over age 9 years was 18.6 (between health unit SD 5.2, 95% confidence interval [CI] = 17.0-20.2). The elderly have a higher suicide rate in every region. The male suicide rates (mean = 26.9, SD 6.4, 95% CI = 24.0-30.0) are higher than female rates (mean = 7.5, SD 1.7, 95% CI = 6.8-8.3) in every region. The factors influencing suicides were different for elderly males and elderly females. In all analyses, suicide rates in elderly females remained essentially stable across age-groups and units and over the years. Elderly male suicide rates varied across units and age-groups and over the years. CONCLUSIONS: Suicide rates are highest in males over age 74 years. There are regional differences in elderly suicide rates and the factors that influence them. Longitudinal and cross-sectional risk factors differ, and there are gender differences in the risk factors. For both elderly males and females, suicide rates appear to be influenced by social factors in the population as a whole, not just in the elderly population. Male and female employment patterns are associated with elderly male suicide rates, even though the latter are not in the labour force. For suicide in elderly women the important factors are population education, income, and migration levels.

Age Distribution↗
PubMed1998

Fertility among a cohort of male sawmill workers exposed to chlorophenate fungicides.

The purpose of this study was to determine whether exposure to chlorophenate fungicides and their dioxin contaminants is associated with male infertility among sawmill workers. The study was conducted using fertility data compiled from 26,487 sawmill workers in 14 British Columbian sawmills. Our analysis was restricted to workers who had been employed for at least 1 continuous year between 1950 and 1985 and to live-births born at least 1 year after the initiation of employment in the period 1955-1988. We assessed fertility trends by internal comparison using Mantel-Haenszel rate ratios and by calculating standardized fertility ratios using an external and an internal reference population. We identified 19,684 births in the study period. Initially, both external and internal analyses showed that sawmill workers from mills using chlorophenates had lower fertility than workers employed in mills not using chlorophenates. After controlling for time since first hire, however, we found no inverse relation between cumulative exposure to chlorophenate fungicides and fertility. Based on the results of our study, there is little evidence for a reduction in fertility among chlorophenate-exposed sawmill workers in British Columbia. The analyses indicate the importance of time since hire as a potentially strong confounder in this type of investigation.

Adult↗
PubMed1997

Outbreak of toxoplasmosis associated with municipal drinking water. The BC Toxoplasma Investigation Team.

BACKGROUND: Outbreaks of toxoplasmosis are recognised infrequently. In March, 1995, a sudden increase of serologically diagnosed cases of acute toxoplasmosis was noted in the Greater Victoria area of British Columbia, Canada. Concurrently, but independently, seven cases of acute toxoplasma retinitis were diagnosed against a background of no cases in the previous 5 years. METHODS: Cases were defined by serological testing, clinical presentation, and residence in Greater Victoria. A screening programme for women who were or had been pregnant was started. Geographical mapping of cases, and case-control studies of symptomatic cases and of women enrolled in the screening programme were done. FINDINGS: 100 individuals aged 6 to 83 years met the definition for an acute, outbreak-related case. 94 resided in Greater Victoria and six had visited it; 19 had retinitis, 51 had lymphadenopathy, four others had symptoms consistent with toxoplasmosis, seven had other symptoms, 18 were symptom-free, and one would not provide information. 36 (0.9%) of 3812 screened pregnant and postnatal women were cases. Excess cases were not detected outside Greater Victoria and no conventional source of toxoplasmosis was implicated. Mapping studies of cases and of the screened women, and both case-control studies showed significant associations between acute infection and residence in the distribution system of one reservoir supplying water to Greater Victoria (ORs or RRs: 3.53, 3.05, 8.27, and 5.42, respectively). The epidemic curve appeared bimodal, with peaks in December, 1994, and March, 1995, that were preceded by increased rainfall and turbidity in the implicated reservoir. INTERPRETATION: A municipal water system that uses unfiltered, chloraminated surface water was the likely source of this large community-wide outbreak of toxoplasmosis.

Adolescent↗