Biomedical subjects

J Brook

Publications and source records attributed to J Brook.

At least 19 recordsLinked to original sources

PubMed2004

Do socioeconomic characteristics modify the short term association between air pollution and mortality? Evidence from a zonal time series in Hamilton, Canada.

STUDY OBJECTIVE: To assess the short term association between air pollution and mortality in different zones of an industrial city. An intra-urban study design is used to test the hypothesis that socioeconomic characteristics modify the acute health effects of ambient air pollution exposure. DESIGN: The City of Hamilton, Canada, was divided into five zones based on proximity to fixed site air pollution monitors. Within each zone, daily counts of non-trauma mortality and air pollution estimates were combined. Generalised linear models (GLMs) were used to test mortality associations with sulphur dioxide (SO(2)) and with particulate air pollution measured by the coefficient of haze (CoH). MAIN RESULTS: Increased mortality was associated with air pollution exposure in a citywide model and in intra-urban zones with lower socioeconomic characteristics. Low educational attainment and high manufacturing employment in the zones significantly and positively modified the acute mortality effects of air pollution exposure. DISCUSSION: Three possible explanations are proposed for the observed effect modification by education and manufacturing: (1) those in manufacturing receive higher workplace exposures that combine with ambient exposures to produce larger health effects; (2) persons with lower education are less mobile and experience less exposure measurement error, which reduces bias toward the null; or (3) manufacturing and education proxy for many social variables representing material deprivation, and poor material conditions increase susceptibility to health risks from air pollution.

Adult↗

PubMed2003

The DNA sequence and analysis of human chromosome 6.

Chromosome 6 is a metacentric chromosome that constitutes about 6% of the human genome. The finished sequence comprises 166,880,988 base pairs, representing the largest chromosome sequenced so far. The entire sequence has been subjected to high-quality manual annotation, resulting in the evidence-supported identification of 1,557 genes and 633 pseudogenes. Here we report that at least 96% of the protein-coding genes have been identified, as assessed by multi-species comparative sequence analysis, and provide evidence for the presence of further, otherwise unsupported exons/genes. Among these are genes directly implicated in cancer, schizophrenia, autoimmunity and many other diseases. Chromosome 6 harbours the largest transfer RNA gene cluster in the genome; we show that this cluster co-localizes with a region of high transcriptional activity. Within the essential immune loci of the major histocompatibility complex, we find HLA-B to be the most polymorphic gene on chromosome 6 and in the human genome.

Animals↗

PubMed2002

Cardiac arrest after administration of Omnipaque radiocontrast medium during endoluminal repair of abdominal aortic aneurysm.

We describe a case of acute cardiovascular collapse in a patient with end-stage renal failure undergoing endoluminal repair of an abdominal aortic aneurysm. The 61-yr-old man suffered cardiac arrest shortly after administration of radiocontrast medium (Omnipaque), during deployment of the endovascular device. He had received the same contrast solution for diagnostic angiography on the previous day. He was successfully resuscitated and recovered completely. The differential diagnosis and management are discussed.

Aortic Aneurysm, Abdominal↗

PubMed2001

Adolescent fears as predictors of depression.

BACKGROUND: Recent studies raise questions on the relationship between adolescent fears and risk for major depression. METHODS: An epidemiologic sample of 776 young people received psychiatric assessments in 1983, 1985-1986, and 1992. Prospective associations were examined between fears in adolescence and future episodes of major depression. RESULTS: Both overall level of fears and specific fear of dark in adolescence predicted future risk for major depression. CONCLUSIONS: Relatively high levels of fear in adolescence represent a risk factor for later episodes of major depression.

Adolescent↗

PubMed2001

Associations between daily cause-specific mortality and concentrations of ground-level ozone in Montreal, Quebec.

The authors investigated the association between daily variations in ozone and cause-specific mortality. Fixed-site air pollution monitors in Montreal, Quebec, provided daily mean levels of ozone, particles, and other gaseous pollutants. Information on the date and underlying cause of death was obtained for residents of Montreal who died in the city between 1984 and 1993. The authors regressed the logarithm of daily counts of cause-specific mortality on mean levels of ozone, after accounting for seasonal and subseasonal fluctuations in the mortality time series, non-Poisson dispersion, and weather variables. The effect of ozone on mortality was generally higher in the warm season and among persons aged 65 years or over. For an increase in the 3-day running mean concentration of ozone of 21.3 microg/m(3), the percentage of increase in daily deaths in the warm season was the following: nonaccidental deaths, 3.3% (95% confidence interval (CI): 1.7, 5.0); cancer, 3.9% (95% CI: 1.0, 6.91); cardiovascular diseases, 2.5% (95% CI: 0.2, 5.0); and respiratory diseases, 6.6% (95% CI: 1.8, 11.8). These results were independent of the effects of other pollutants and were consistent with a log-linear response function.

Accidents↗

PubMed2001

The association between daily mortality and ambient air particle pollution in Montreal, Quebec. 1. Nonaccidental mortality.

This study was undertaken to determine whether variations in concentrations of particles in the ambient air of Montreal, Quebec, during the period 1984 to 1993, were associated with daily variations in nonaccidental mortality. Fixed-site air pollution monitors in Montreal provided daily mean levels of various measures of particulates and gaseous pollutants. Total sulfates were also measured daily (1986-1993) at a monitoring station 150 km southeast of the city (Sutton, Quebec). We estimated associations for PM(2.5), PM(10), total suspended particles, coefficient of haze (COH), extinction coefficient, and sulfates. We used coefficient of haze, extinction coefficient, and Sutton sulfates to predict fine particles and sulfates for days that were missing. To estimate the associations between nonaccidental mortality and ambient air particles, we regressed the logarithm of daily counts of nonaccidental mortality on the daily mean levels for the above measures of particulates, after accounting for seasonal and subseasonal fluctuations in the mortality time series, non-Poisson dispersion, weather variables, and gaseous pollutants. There were 140,939 residents of Montreal who died during the study period. We found evidence of associations between daily nonaccidental deaths and most measures of particulate air pollution. For example, the mean percentage increase (MPC) for an increase of total suspended particles of 28.57 microg/m(3) (interquartile range, IQ), evaluated at lag 0 days, was 1.86% (95% confidence interval (CI): 0.00-3.76%), and for an increase of coefficient of haze (IQ=18.5 COH units per 327.8 linear m) the MPC was 1.44% (95% CI: 0.75-2.14%). These results are similar to findings from other studies (the mean percentage increase in nonaccidental deaths for a 100 microg/m(3) increase in daily total suspended particles was 6.7%). We also found increases for fine particles and for inhalable particles, but the confidence intervals included unity. All measures of sulfates showed increased daily mortality; e.g., the MPC for sulfates from fine particles (IQ=3.51 microg/m(3)) was 1.86% (95% CI: 0.40-3.35%). We generally found higher excesses in daily mortality for persons 65 years of age and for exposures averaged across lags 0, 1, and 2 days. The slope of the association between daily mortality and ambient air particles in Montreal, which has lower levels of pollution than most major urban centers, is similar to that reported in most other industrialized cities. This study therefore provides further evidence that the association is linear and that any threshold effect, should it exist, would be found at lower levels of air pollution than those found in Montreal.

Aged↗

PubMed2001

The association between daily mortality and ambient air particle pollution in Montreal, Quebec. 2. Cause-specific mortality.

This study was undertaken to determine whether variations in concentrations of particulates in the ambient air of Montreal, Quebec, during the period 1984 to 1993, were associated with daily variations in cause-specific daily mortality. Fixed-site air pollution monitors in Montreal provided daily mean levels of various measures of particles and gaseous pollutants. Total sulfate was also measured daily (1986-1993) at a monitoring station 150 km southeast of the city (Sutton, Quebec). We used coefficient of haze (COH), extinction coefficient, and sulfate from the Sutton station to predict fine particles and sulfate from fine particles for days that were missing. We estimated associations between cause-specific mortality and PM(2.5), PM(10), predicted fine particles and fine sulfate particles, total suspended particles, coefficient of haze, extinction coefficient, and total sulfate measured at the Sutton station. We selected a set of underlying causes of death, as recorded on the death certificates, as the endpoint and then regressed the logarithm of daily counts of cause-specific mortality on the daily mean levels for the above measures of particulates, after accounting for seasonal and subseasonal fluctuations in the mortality time series, non-Poisson dispersion, weather variables, and gaseous pollutants. We found positive and statistically significant associations between the daily measures of ambient particle mass and sulfate mass and the deaths from respiratory diseases and diabetes. The mean percentage change in daily mortality (MPC), evaluated at the interquartile range for pollutants averaged over the day of death and the preceding 2 days, for deaths from respiratory diseases was MPC(COH)=6.90% (95% CI: 3.69-10.21%), MPC(Predicted PM2.5)= 9.03% (95% CI: 5.83- 12.33%), and MPC(Sutton sulfate)=4.64% (95% CI: 2.46-6.86%). For diabetes, the corresponding estimates were MPC(COH)=7.50% (95% CI: 1.96-13.34%), MPC(Predicted PM2.5)=7.59% (95% CI: 2.36-13.09%), and MPC(Sutton sulfate)=4.48% (95% CI: 1.08-7.99%). Among individuals older than 65 years at time of death, we found consistent associations across our metrics of particles for neoplasms and coronary artery diseases. Associations with sulfate mass were also found among elderly persons who died of cardiovascular diseases and of lung cancer. These associations were consistent with linear relationships. The associations found for respiratory diseases and for cardiovascular diseases, especially in the elderly, are in line with some of the current hypotheses regarding mechanisms by which ambient particles may increase daily mortality. The positive associations found for cancer and for diabetes may be understood through a general hypothesis proposed by Frank and Tankersley, who suggested that persons in failing health may be at higher risk for external insults through the failure of regulating physiological set points. The association with diabetes may be interpreted in light of recent toxicological findings that inhalation of urban particles in animals increases blood pressure and plasmatic levels of endothelins that enhance vasoconstriction and alter electrophysiology. Further research to confirm these findings and to determine whether they are causal is warranted.

Aged↗

PubMed2001

Identification of persons with cardiorespiratory conditions who are at risk of dying from the acute effects of ambient air particles.

This study was undertaken to identify subgroups of the population susceptible to the effects of ambient air particles. Fixed-site air pollution monitors in Montreal, Quebec, Canada, provided daily mean levels of various measures of particulates and gaseous pollutants. Total sulfates were also measured daily (1986-1993) at a monitoring station 150 km southeast of the city (Sutton, Quebec, Canada). We used coefficient of haze (COH), extinction coefficient, and Sutton sulfates to predict fine particles and sulfates from a fine particles model for days that were missing. We used the universal Quebec medicare system to obtain billings and prescriptions for each Montreal resident who died in the city from 1984 to 1993. These data were then used to define cardiovascular and respiratory conditions that subjects had before death. Using standard Poisson regression time-series analyses, we estimated the association between daily nonaccidental mortality and daily concentrations of particles in the ambient air among persons with cardiovascular and respiratory conditions diagnosed before death. We found no persuasive evidence that daily mortality increased when ambient air particles were elevated for subgroups of persons with chronic upper respiratory diseases, airways disease, cerebrovascular diseases, acute coronary artery disease, and hypertension. However, we found that daily mortality increased linearly as concentrations of particles increased for persons who had acute lower respiratory diseases, chronic coronary artery diseases (especially in the elderly), and congestive heart failure. For this latter set of conditions, the mean percent increase in daily mortality (MPC) for an increase in the COH across its interquartile range (18.5 COH units per 327.8 linear meters), averaged over the day of death and the 2 preceding days, was MPC = 5.09% [95% confidence interval (CI) 2.47-7.79%], MPC = 2.62 (95% CI 0.53-4.75%), and MPC = 4.99 (95% CI 2.44-7.60%), respectively. Adjustments for gaseous pollutants generally attenuated these associations, although the general pattern of increased daily mortality remained. In addition, there appeared to be a stronger association in the summer season. The positive associations found for persons who had acute lower respiratory diseases and congestive heart failure are consistent with some prevailing hypotheses and may also be consistent with recent toxicologic data implicating endothelins. Further epidemiologic studies are required to confirm these findings.

Aged↗

PubMed2000

Association between particulate- and gas-phase components of urban air pollution and daily mortality in eight Canadian cities.

Although some consensus has emerged among the scientific and regulatory communities that the urban ambient atmospheric mix of combustion related pollutants is a determinant of population health, the relative toxicity of the chemical and physical components of this complex mixture remains unclear. Daily mortality rates and concurrent data on size-fractionated particulate mass and gaseous pollutants were obtained in eight of Canada's largest cities from 1986 to 1996 inclusive in order to examine the relative toxicity of the components of the mixture of ambient air pollutants to which Canadians are exposed. Positive and statistically significant associations were observed between daily variations in both gas- and particulate-phase pollution and daily fluctuations in mortality rates. The association between air pollution and mortality could not be explained by temporal variation in either mortality rates or weather factors. Fine particulate mass (less than 2.5 microns in average aerometric diameter) was a stronger predictor of mortality than coarse mass (between 2.5 and 10 microns). Size-fractionated particulate mass explained 28% of the total health effect of the mixture, with the remaining effects accounted for by the gases. Forty-seven elemental concentrations were obtained for the fine and coarse fraction using nondestructive x-ray fluorescence techniques. Sulfate concentrations were obtained by ion chromatography. Sulfate ion, iron, nickel, and zinc from the fine fraction were most strongly associated with mortality. The total effect of these four components was greater than that for fine mass alone, suggesting that the characteristics of the complex chemical mixture in the fine fraction may be a better predictor of mortality than mass alone. However, the variation in the effects of the constituents of the fine fraction between cities was greater than the variation in the mass effect, implying that there are additional toxic components of fine particulate matter not examined in this study whose concentrations and effects vary between locations. One of these components, carbon, represents half the mass of fine particulate matter. We recommend that measurements of elemental and organic carbon be undertaken in Canadian urban environments to examine their potential effects on human health.

Air Pollutants↗

PubMed1999

Adolescent depressive symptoms as predictors of adult depression: moodiness or mood disorder?

OBJECTIVE: The authors' goal was to examine the relationship between subclinical depressive symptoms in adolescence and major depressive episodes in adulthood. METHOD: An epidemiologic sample of 776 young people received psychiatric assessments in 1983, 1985, and 1992. Among adolescents not meeting criteria for major depression, the authors estimated the magnitude of the association between subclinical adolescent depressive symptoms and adult major depression. RESULTS: Symptoms of major depression in adolescence strongly predicted an adult episode of major depression: having depressive symptoms more than two-standard-deviations above the mean in number predicted a two-fold to three-fold greater risk for an adult major depressive episode. CONCLUSIONS: Symptoms of depression in adolescence strongly predict an episode of major depression in adulthood, even among adolescents without major depression.

Adolescent↗

PubMed1998

Prospective associations between somatic illness and mental illness from childhood to adulthood.

The association between somatic illness and psychiatric illness is well established in adults but is less clear in childhood and adolescence. A cohort of over 700 randomly selected children in Upstate New York were studied from ages 1-10 years in 1975 to young adulthood in 1992. Psychiatric and physical health were assessed by means of follow-up youth and parent interviews at 8-, 2 1/2-, and 6-year intervals (in 1983, 1985-1986, and 1991-1993). Cross-sectional and longitudinal analyses investigated: 1) the consistency of the relation between physical illness and mental illness in childhood; 2) the specificity of major depressive disorder (MDD) in accounting for the relation; 3) the specificity of immunologically mediated medical disorders in this relation; and 4) whether this relation was attributable to risks associated with low socioeconomic status. Cross-sectionally, ill health was associated with increased risk of psychiatric disorders at all ages, with significant odds ratios (ORs) ranging from 1.76 to 3.26. In prospective analyses, ill health increased the risk of new-onset MDD at all ages (ORs = 2.05-4.48). MDD also predicted subsequent ill health, independent of prior health problems (ORs = 3.81 and 4.04). Relations were not attributable to familial socioeconomic status. Associations were particularly strong between MDD and medical disorders associated with alterations in immunologic factors (ORs = 1.83-6.41). Theories of common immune-mediated vulnerabilities to medical illness and depression are consistent with these associations.

Adolescent↗

PubMed1998

The risk for early-adulthood anxiety and depressive disorders in adolescents with anxiety and depressive disorders.

BACKGROUND: Various studies find relationships among anxiety and depressive disorders of adolescence and adulthood. This study prospectively examines the magnitude of longitudinal associations between adolescent and adult anxiety or depressive disorders. METHODS: An epidemiologically selected sample of 776 young people living in upstate New York received DSM-based psychiatric assessments in 1983, 1985, and 1992 using structured interviews. The magnitude of the association between adolescent and adult anxiety or depressive disorders was quantified using odds ratios generated from logistic regression analyses and from a set of latent Markov analyses. We focus on longitudinal associations among narrowly defined DSM anxiety or depressive disorders. RESULTS: In simple logistic models, adolescent anxiety or depressive disorders predicted an approximate 2- to 3-fold increased risk for adulthood anxiety or depressive disorders. There was evidence of specificity in the course of simple and social phobia but less specificity in the course of other disorders. Results from the analyses using latent variables suggested that while most adolescent disorders were no longer present in young adulthood, most adult disorders were preceded by adolescent disorders. CONCLUSIONS: An anxiety or depressive disorder during adolescence confers a strong risk for recurrent anxiety or depressive disorders during early adulthood. Most anxiety and depressive disorders in young adults may be preceded by anxiety or depression in adolescence.

Adolescent↗

PubMed1997

Psychiatric symptoms in adolescence as predictors of obesity in early adulthood: a longitudinal study.

OBJECTIVES: This study examined the longitudinal relationship between psychopathology and obesity in young adulthood. METHODS: More than 700 youth in a population-based sample were psychiatrically assessed in 1983 (mean age = 14 years) and 1992 (mean age = 22 years). Self-reported body mass index (BMI) in 1992 was regressed on measures of depression and conduct disorder as well as a set of covariates including indices of physical health, social class, intelligence, and cigarette and alcohol use. Associations were examined with BMI treated as a continuous variable and with a binary index of obesity derived from the BMI distribution in each gender. RESULTS: BMI in young adults was positively related to a number of covariates. With all covariates controlled, BMI was inversely related to adult depressive symptoms in males but not females. BMI was positively related to adolescent symptoms of conduct disorder in both sexes. Similar associations were found between psychiatric symptoms and obesity. CONCLUSIONS: Conduct disorder symptoms in adolescence predicted BMI and obesity in early adulthood. These associations remained after controlling for factors that can affect the association between psychopathology and obesity.

Adolescent↗

PubMed1996

Discriminating depression and anxiety in youth: a role for diagnostic criteria.

OBJECTIVE: To test the hypothesis that anxiety and depression in youth, as in adults, become increasingly discriminable when youth meet criteria for an emotional disorder. METHOD: The study uses cross-sectional data at two points in time from a large (n = 776) community sample of youths, aged eight to twenty. Associations between major depression and five anxiety disorders (overanxious, obsessive compulsive and separation anxiety disorders, and social and simple phobias) are examined by symptom scale and diagnosis. RESULTS: Anxiety and depression are moderately correlated, and substantially comorbid by diagnostic category. Symptoms are more discriminable among youths with diagnoses of at least one emotional disorder than among those without. A single factor accounts for symptoms among the non-diagnosed but multiple factors are required for the diagnosed group. CONCLUSIONS: Anxiety and depression are discriminable among youth who meet criteria for a specific emotional disorder but more highly associated among youths without such a diagnosis. This suggests that in youth, as has been shown in adults, depression and anxiety become increasingly discriminable as emotional psychopathology becomes more severe.

Adolescent↗

PubMed1996

Refugees' and immigrants' mental health: association of demographic and post-immigration factors.

Several demographic and post-immigration factors related to self-reported symptoms of anxiety and depression of immigrants in New Zealand were examined in a study involving a sample of 129 Southeast Asian refugees, 57 Pacific Island immigrants, and 63 British immigrants to New Zealand. A questionnaire and the Hopkins Symptom Checklist-25 (HSCL-25) in English and in three Southeast Asian translations were administered, followed by an interview in English or with an interpreter. The findings suggest that demographic characteristics are not associated with symptom level. Post-immigration factors, such as experiencing discrimination in New Zealand, not having close friends, being unemployed, and spending most of one's time with one's own ethnic group affected anxiety and depression scores.

Adult↗

PubMed1996

The association between major depression and headache: results of a longitudinal epidemiologic study in youth.

Retrospective epidemiologic research in adults suggests that a long-term association between major depression and headache arises during childhood or adolescence. This study uses data from a prospective epidemiologic study to examine the association between major depression and headache from late childhood into early adulthood. An epidemiologically selected sample of 776 youth, aged 9-18, was assessed psychiatrically in 1983 using DISC interviews with both youth and parent informants. Reassessments were conducted in 1985-1986 and 1992. Current and past histories of functionally impairing migraine or chronic headache were elicited in both 1985-1986 and 1992. Regression analyses examined the relationships between major depression and headache status. The prevalence of current functionally impairing headache was approximately 10% in both 1985-1986 and 1992. There were lifetime and cross-sectional associations between headache and major depression. Headache was approximately twice as common in depressed adolescents compared with nondepressed adolescents. Major depression in adolescents, without current or past headache, prospectively predicted the new onset of headaches in young adulthood. Among adolescents who had no history of chronic impairing headache in 1985-1986, those with current major depression faced a nearly tenfold increased risk of developing such headaches at some time during the next 7 years. Consistent with findings of retrospective studies among adults, a longitudinal/ developmental relationship between major depression and functionally impairing headache was found in this prospective epidemiologic study of youth. These findings suggest that (1) neurochemical and pharmacologic commonalities between depression and headache should receive further investigation and that (2) it may be clinically useful to inquire about family history of headache syndromes in adolescents with major depression because such questioning may provide insight about the risk of subsequent functionally impairing headache in a depressed adolescent.

Adolescent↗

PubMed1996

The mental health pattern of migrants: is there a euphoric period followed by a mental health crisis?

Sluzki's 1986 mental health model of the migratory process was tested with migrants (both refugees and immigrants), to New Zealand. Its central feature, suggesting an initial symptom free and euphoric phase after arrival in the country of settlement, followed by a crisis stage, was examined for 129 Southeast Asian refugees, 57 Pacific Island immigrants and 63 British immigrants. A questionnaire and the Hopkins Symptom Checklist-25, in English and in three Southeast Asian language translations, were administered face-to-face. All respondents had arrived in New Zealand within the last 15 years. The findings did not support Sluzki's model. Refugees and immigrants in the group with less than six months of residence were not symptom free. Neither did the group with six months to six years residence demonstrate a deterioration in mental health. However, mean depression levels were slightly lower for those who had lived in New Zealand for over six years, suggesting that mental health may improve the longer both refugees and immigrants reside in the host country.

Anxiety Disorders↗

PubMed1996

Emotional problems during youth as predictors of stature during early adulthood: results from a prospective epidemiologic study.

OBJECTIVE: Adults with emotional disorders exhibit abnormalities in growth hormone secretion. If these abnormalities were to occur during childhood, they could affect growth. The purpose of this study was to examine the relationship between youth emotional disorders and stature in early adulthood. METHODS: Using data from a prospective epidemiologic study of youth psychopathologic status, we used linear regression to examine the prospective relationship between anxiety disorders (separation anxiety and over-anxious disorders) or major depressive disorder in youth and stature in early adulthood. RESULTS: Anxiety disorders during childhood prospectively predicted relatively short stature in early adulthood among females, accounting for more than 5% of the variance in adult height. However, these associations were not found among males. CONCLUSIONS: There may be an association between abnormalities in growth and emotional problems in youth. Further research should examine biological measures related to growth among youth with emotional disorders.

Adolescent↗