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Biomedical subjects

J Schwartz

Publications and source records attributed to J Schwartz.

At least 37 records · Page 2Linked to original sources
PubMed2004

Association between air pollution exposure and exhaled nitric oxide in an elderly population.

BACKGROUND: Animal models suggest that the cardiovascular effects of air pollution result in part from inflammation caused by proinflammatory mediators originating in the lung. In a human study of the cardiovascular effects of air pollution, we aimed to evaluate the potential association between air pollution levels and the fraction of exhaled nitric oxide (FE(NO)), a non-invasive measure of airway inflammation. METHODS: Breath samples were collected weekly between September and December 2000 in a community based group of elderly subjects (median age 70.7 years) in Steubenville, Ohio. The samples were analysed for NO. Air pollution levels were measured concurrently at a central site monitor. RESULTS: An increase in the 24 hour average PM(2.5) concentration of 17.7 micro g/m(3) was associated with an increase in FE(NO) of 1.45 ppb (95% CI 0.33 to 2.57) in models adjusted for subject, week of study, day of the week, hour of the day, ambient barometric pressure, temperature, and relative humidity. This represents a change of approximately 15% compared with the mean FE(NO) in the cohort (9.9 ppb). A significant association was also observed for a 24 hour moving average of ambient NO (0.83 ppb increase, 95% CI 0.26 to 1.40). In two-pollutant models, the magnitude and precision of the PM(2.5) effect was not reduced and the ambient NO effect was no longer significant. The associations between FE(NO) and PM(2.5) were significantly higher in subjects with a doctor's diagnosis of COPD (p value for interaction = 0.03). CONCLUSIONS: Ambient pollution may lead to airway inflammation as measured by FE(NO). These subclinical inflammatory changes may be an important step in the pathogenesis of the cardiopulmonary effects induced by exposure to air pollution.

Aged↗
PubMed2003

The influence of various physiological challenges on permanent changes to the cardiovascular system.

The concept of fetal programming provides an intellectual framework that links physiological adaptations that occur during development to permanent changes in postnatal regulatory systems. Recent research in the area of cardiovascular programming has highlighted the mechanisms by which these changes exert their effects. The aim of this review is to integrate some of the literature on nutritional changes, exposure to excess glucocorticoids and other challenges during development as they provide support for various mechanisms of programming of the cardiovascular system.

Animals↗
PubMed2003

Investigating the dose-response relation between air pollution and total mortality in the APHEA-2 multicity project.

BACKGROUND: Several recent studies have reported significant health effects of air pollution even at low levels of air pollutants, but in most of these studies linear non-threshold relations were assumed. AIMS: To investigate the NO2 mortality dose-response association in nine cities participating in the APHEA-2 project using two different methods: the meta-smooth and the cubic spline method. METHODS: The meta-smooth method developed by Schwartz and Zanobetti is based on combining individual city non-parametric smooth curves; the cubic spline method developed within the APHEA-2 project combines individual city estimates of cubic spline shaped dose-response relations. The meta-smooth method is easier and faster to implement, but the cubic spline method is more flexible for further investigation of possible heterogeneity in the dose-response curves among cities. RESULTS: In the range of the pollutant common to all cities the two methods gave similar and comparable curves. Using the cubic spline method it was found that smoking prevalence acts as an effect modifier with larger NO2 effects on mortality at lower smoking prevalence. CONCLUSIONS: The NO2-mortality association in the cities included in the present analysis, could be adequately estimated using the linear model. However, investigation of the city specific dose-response curves should precede the application of linear models.

Air Pollutants↗
PubMed2003

Effect of trihalomethane exposure on fetal development.

AIMS: To examine the effect of trimester specific and pregnancy average total trihalomethane (TTHM) exposure on infant birth weight, low birth weight, and intrauterine growth retardation in term births, as well as gestational age and preterm delivery in all births. METHODS: Cross sectional analysis of 56 513 singleton infants born to residents of Massachusetts during 1990. City specific aggregate data were used to estimate maternal exposure to TTHM concentration; individual maternal information was used to adjust for confounding. RESULTS: Increased pregnancy average and second trimester TTHM exposure were associated with small for gestational age and reductions in birth weight after adjusting for potential confounding variables. Compared to </=60 micro g/l, pregnancy average TTHM exposure over 80 micro g/l was associated with a 32 g reduction in birth weight. There was a 23 g reduction in birth weight in infants born to mothers exposed to greater than 80 micro g/l TTHM during the second trimester. For each 20 micro g/l increase in TTHM, the estimated reduction in birth was 2.8 g for pregnancy average exposure and 2.6 g for second trimester exposure. An increased risk of small for gestational age births was found for pregnancy average (odds ratio (OR) 1.14; 95% CI 1.02 to 1.26) and second trimester (OR 1.13, 95% CI 1.03 to 1.24) TTHM levels greater than 80 micro g/l. There was no evidence of an association between preterm delivery and increased TTHM levels, but there were slight increases in gestational duration associated with TTHM concentrations. CONCLUSIONS: Maternal exposure to THMs may be associated with fetal growth retardation. Our findings are consistent with most previous work, although we generally found smaller effects of TTHMs on low birth weight and intrauterine growth retardation.

Adolescent↗
PubMed2003

Respiratory effects of sulphur dioxide: a hierarchical multicity analysis in the APHEA 2 study.

BACKGROUND: Sulphur dioxide (SO(2)) was associated with hospital admissions for asthma in children in the original APHEA study, but not with other respiratory admissions. AIMS: To assess the association between daily levels of SO(2) and daily levels of respiratory admissions in a larger and more recent study. METHODS: Time series of daily counts of hospital emergency admissions were constructed for asthma at ages 0-14 years and 15-64 years, COPD and asthma, and all respiratory admissions at ages 65+ years in the cities of Birmingham, London, Milan, Paris, Rome, Stockholm, and in the Netherlands for periods of varying duration between the years 1988 and 1997. A two stage hierarchical modelling approach was used. In the first stage generalised additive Poisson regression models were fitted in each city controlling for weather and season. These results were then combined across cities in a second stage ecological regression that looked at potential effect modifiers. RESULTS: For an increase of 10 micro g/m(3) of SO(2) the daily number of admissions for asthma in children increased 1.3% (95% CI 0.4% to 2.2%). Effect modification among cities by levels of other air pollutants or temperature was not found. The SO(2) effect disappeared after controlling for PM(10) or CO, but correlation among these pollutants was very high. Other respiratory admissions were not associated with SO(2). CONCLUSION: SO(2) is associated with asthma admissions in children, indicating that reduction in current air pollution levels could lead to a decrease in the number of asthma admissions in children in Europe.

Adolescent↗
PubMed2003

Short-term effects of ambient particles on mortality in the elderly: results from 28 cities in the APHEA2 project.

Within the framework of the APHEA2 (Air Pollution on Health: a European Approach) project, the effects of ambient particles on mortality among persons > or = 65 yrs were investigated. Daily measurements for particles with a 50% cut-off aerodynamic diameter of 10 microm (PM10) and black smoke (BS), as well as the daily number of deaths among persons > or = 65 yrs of age, from 29 European cities, have been collected. Data on other pollutants and meteorological variables, to adjust for confounding effects and data on city characteristics, to investigate potential effect modification, were also recorded. For individual city analysis, generalised additive models extending Poisson regression, using a locally weighted regression (LOESS) smoother to control for seasonal effects, were applied. To combine individual city results and explore effect modification, second stage regression models were applied. The per cent increase (95% confidence intervals), associated with a 10 microg x m(-3) increase in PM10, in the elderly daily number of deaths was 0.8%, (0.7-0.9%) and the corresponding number for BS was 0.6%, (0.5-0.8%). The effect size was modified by the long-term average levels of nitrogen dioxide (higher levels were associated with larger effects), temperature (larger effects were observed in warmer countries), and by the proportion of the elderly in each city (a larger proportion was associated with higher effects). These results indicate that ambient particles have effects on mortality among the elderly, with relative risks comparable or slightly higher than those observed for total mortality and similar effect modification patterns. The effects among the older persons are of particular importance, since the attributable number of events will be much larger, compared to the number of deaths among the younger population.

Aged↗
PubMed2002

Corticotrophs and peptides.

Corticotrophs were long thought to be a static, homogeneous population of cells that respond positively to hypothalamic stimulation, are inhibited by glucocorticoid feedback and secrete a single biologically active peptide, ACTH(1-39). Our current understanding is that this is an oversimplification and corticotrophs are a dynamic and more complex group of cells. The biosynthetic precursors of ACTH and other cleavage products of proopiomelanocortin (POMC) have been found to be secreted by anterior pituitary cells, to circulate and to have biological activity. POMC and the biosynthetic intermediate, pro-ACTH, exert activity antagonistic to ACTH(1-39) on glucocorticoid secretion by adrenal cells, and other derivatives of POMC are mitogenic to adrenocortical cells. In terms of responses to hypothalamic and peripheral factors, corticotrophs are functionally heterogeneous. This is reflected in the sensitivity of individual subtypes of corticotrophs to CRH, vasopressin and glucocorticoids. There is a functional plasticity amongst the various types of corticotrophs. During gestation, in fetal sheep, changes occur in the overall ACTH-secretory responses to CRH relative to vasopressin, the proportions of total corticotrophs that respond to the respective peptides and the average secretory response of individual cells. Corticotrophs also respond to locally produced pituitary factors. Local actions of leukaemia inhibitory factor are demonstrated by the effects of immunoneutralization of the peptide in pituitary cells. Urocortin and preproTRH(178-199) are locally produced peptides with potent stimulatory and inhibitory actions on corticotrophs, respectively. The specific roles of these peptides are under investigation.

Adrenocorticotropic Hormone↗
PubMed2002

Short-term effects of particulate air pollution on cardiovascular diseases in eight European cities.

STUDY OBJECTIVE: As part of the APHEA project this study examined the association between airborne particles and hospital admissions for cardiac causes (ICD9 390-429) in eight European cities (Barcelona, Birmingham, London, Milan, the Netherlands, Paris, Rome, and Stockholm). All admissions were studied, as well as admissions stratified by age. The association for ischaemic heart disease (ICD9 410-413) and stroke (ICD9 430-438) was also studied, also stratified by age. DESIGN: Autoregressive Poisson models were used that controlled for long term trend, season, influenza epidemics, and meteorology to assess the short-term effects of particles in each city. The study also examined confounding by other pollutants. City specific results were pooled in a second stage regression to obtain more stable estimates and examine the sources of heterogeneity. MAIN RESULTS: The pooled percentage increases associated with a 10 micro g/m(3) increase in PM(10) and black smoke were respectively 0.5% (95% CI: 0.2 to 0.8) and 1.1% (95% CI: 0.4 to 1.8) for cardiac admissions of all ages, 0.7% (95% CI: 0.4 to 1.0) and 1.3% (95% CI: 0.4 to 2.2) for cardiac admissions over 65 years, and, 0.8% (95% CI: 0.3 to 1.2) and 1.1% (95% CI: 0.7 to 1.5) for ischaemic heart disease over 65 years. The effect of PM(10) was little changed by control for ozone or SO(2), but was substantially reduced (CO) or eliminated (NO(2)) by control for other traffic related pollutants. The effect of black smoke remained practically unchanged controlling for CO and only somewhat reduced controlling for NO(2). CONCLUSIONS: These effects of particulate air pollution on cardiac admissions suggest the primary effect is likely to be mainly attributable to diesel exhaust. Results for ischaemic heart disease below 65 years and for stroke over 65 years were inconclusive.

Adult↗
PubMed2002

Associations between markers of respiratory morbidity in European children.

School-aged children often experience acute respiratory symptoms. In a multicentre European study, the association between chronic respiratory symptoms (reported in a questionnaire), skin-prick test results, and lung function, and the occurrence of acute respiratory morbidity, was examined among children aged 6-12 yrs with chronic respiratory symptoms. Children with chronic respiratory symptoms, living in 10 European countries, were selected from a parent-completed questionnaire (n=4,307). Atopy was measured with skin-prick tests, and lung function with spirometry. A total of 1,854 (86% of those in the initial cohort) children kept a successful daily diary regarding their respiratory symptoms for 2-3 months. In multivariate logistic regression analyses, children with asthmatic symptoms, particularly those with doctor-diagnosed asthma, had a greater risk of occurrence of lower respiratory symptoms (odds ratio (OR): 6.12; 95% confidence interval (CI): 4.99-8.35) than children with a dry nocturnal cough as their only symptom. Atopy, particularly a positive reaction to indoor allergens, was significantly associated with occurrence of lower respiratory symptoms. For atopy the OR was 1.62 (95% CI: 1.34-1.96). A reduced level of maximal mid-expiratory flow was associated with an increased risk of lower respiratory symptoms, cough and phlegm. The associations were similar in Scandinavia, Central Eastern, Western and Southern Europe. To conclude, asthmatic symptoms reported in a questionnaire, atopic status and a reduced level of maximal mid-expiratory flow were associated with the occurrence of acute respiratory symptoms, especially those of lower respiratory symptoms.

Acute Disease↗
PubMed2002

Increased asthma medication use in association with ambient fine and ultrafine particles.

The association between particulate air pollution and asthma medication use and symptoms was assessed in a panel study of 53 adult asthmatics in Erfurt, Germany in winter 1996/1997. Number concentrations of ultrafine particles, 0.01-0.1 microm in diameter (NC(0.01-0.1), mean 17,300 x cm(-3), and mass concentrations of fine particles 0.01-2.5 microm in diameter (MC(0.01-2.5)), mean 30.3 microg x m(-3), were measured concurrently. They were not highly correlated (r=0.45). The associations between ambient particle concentrations and the prevalence of inhaled beta2-agonist, corticosteroid use and asthma symptoms, were analysed separately with logistic regression models, adjusting for trend, temperature, weekend, holidays, and first order autocorrelation of the error. Cumulative exposures over 14 days of ultrafine and fine particles were associated with corticosteroid use. Beta2-agonist use was associated with 5-day mean NC(0.01-0.1) and MC(0.01-2.5). The prevalence of asthma symptoms was associated with ambient particle concentrations. The results suggest that reported asthma medication use and symptoms increase in association with particulate air pollution and gaseous pollutants such as nitrogen dioxide.

Adrenergic beta-Agonists↗
PubMed2002

Growth hormone regulated gene expression.

Growth hormone (GH) regulated gene expression contributes to many of the effects of GH on cellular metabolism, growth and differentiation. Study of model systems has revealed several mechanisms by which GH regulates gene expression. Regulation of expression of the proto-oncogene c-fos involves STAT-, MAPK, and PI-3K-mediated changes in transcripton factors. STAT 5 plays important roles in regulation of spi 2.1 expression and in the sexually dimorphic expression of some liver genes. GH-regulated STAT 5 has also been implicated in regulation of other physiologically important genes, including those encoding components of the IGF-I axis and insulin. Together, these studies provide insight into GH signaling mechanisms and diverse physiological roles of GH.

Animals↗
PubMed2001

Acute effects of particulate air pollution on respiratory admissions: results from APHEA 2 project. Air Pollution and Health: a European Approach.

The APHEA 2 project investigated short-term health effects of particles in eight European cities. In each city associations between particles with an aerodynamic diameter of less than 10 microm (PM(10)) and black smoke and daily counts of emergency hospital admissions for asthma (0-14 and 15-64 yr), chronic obstructive pulmonary disease (COPD), and all-respiratory disease (65+ yr) controlling for environmental factors and temporal patterns were investigated. Summary PM(10) effect estimates (percentage change in mean number of daily admissions per 10 microg/m(3) increase) were asthma (0-14 yr) 1.2% (95% CI: 0.2, 2.3), asthma (15-64 yr) 1.1% (0.3, 1.8), and COPD plus asthma and all-respiratory (65+ yr) 1.0% (0.4, 1.5) and 0.9% (0.6, 1.3). The combined estimates for Black Smoke tended to be smaller and less precisely estimated than for PM(10). Variability in the sizes of the PM(10) effect estimates between cities was also investigated. In the 65+ groups PM(10) estimates were positively associated with annual mean concentrations of ozone in the cities. For asthma admissions (0-14 yr) a number of city-specific factors, including smoking prevalence, explained some of their variability. This study confirms that particle concentrations in European cities are positively associated with increased numbers of admissions for respiratory diseases and that some of the variation in PM(10) effect estimates between cities can be explained by city characteristics.

Acute Disease↗
PubMed2001

Alignment delays in the N = Z nuclei (72)Kr, (76)Sr, and (80)Zr.

The ground state rotational bands of the N = Z nuclei (72)Kr, (76)Sr, and (80)Zr have been extended into the angular momentum region where rotation alignment of particles is normally expected. By measuring the moments of inertia of these bands we have observed a consistent increase in the rotational frequency required to start pair breaking, when compared to neighboring nuclei. (72)Kr shows the most marked effect. It has been widely suggested that these "delayed alignments" arise from np-pairing correlations. However, alignment frequencies are very sensitive to shape degrees of freedom and normal pairing, so the new experimental observations are still open to interpretation.

Journal Article↗
PubMed2001

Effect of melatonin on hemolymph glucose and lactate levels in the fiddler crab Uca pugilator.

Melatonin was injected into intact and eyestalk-ablated fiddler crabs (Uca pugilator), and its effects on hemolymph glucose and lactate levels were studied. In intact crabs, glucose and lactate levels cycled simultaneously, with peaks occurring during early and late photophase. Melatonin caused a shift in the glucose and lactate cycles, with only one peak occurring closer to mid-photophase. In eyestalk-ablated animals, the glucose rhythmicity was lost; lactate cycled, but levels were significantly lower than in intact animals. Melatonin caused a delayed hyperglycemia in eyestalk-ablated animals, with concurrent but much lower increases in lactate. Overall, melatonin demonstrated delayed hyperglycemic effects that do not appear to be mediated solely via eyestalk factors such as crustacean hyperglycemic hormone (CHH), though involvement of the eyestalks cannot be ruled out. An influence on extra-eyestalk CHH secretion is a potential mechanism of melatonin activity.

Animals↗
PubMed2001

Are diabetics more susceptible to the health effects of airborne particles?

Convincing evidence now exists that particulate air pollution exacerbates heart and lung disease, leading to increased morbidity and mortality. The populations particularly susceptible to these exposures are still unclear. Recent work on potential mechanisms of action of particulate air pollution point to pathways also influenced by diabetes. We examined whether diabetes modified the effect of airborne particles by looking at the association of PM(10) with hospital admissions for heart and lung disease in persons with or without diabetes as a comorbidity. In addition we stratified by age within persons with and without diabetes. We used Medicare data for Cook County, Illinois for the years 1988-1994, and found that a 10 microg/m(3) increase in PM(10) was associated with a 2.01% (95% CI 1.40-2.62%) increase in admissions for heart disease with diabetes, but only a 0.94% (95% CI 0.61-1.28%) increase in persons without diabetes. Similar effect modification was not seen for lung diseases. When analyzing by age we found twice the PM(10)-associated risk for heart disease in diabetics than nondiabetics in both age groups. We found for pneumonia admissions that diabetes is an effect modifier in the younger age group, and for COPD in the older age group. We conclude that persons with diabetes are a susceptible population.

Aged↗
PubMed2001

Association of heart rate variability with occupational and environmental exposure to particulate air pollution.

BACKGROUND: Airborne particulate matter has been linked to excess morbidity and mortality. Recent attention has focused on the effects of particulate exposure on cardiac autonomic control. Inhaled particulates may affect the autonomic nervous system either directly, by eliciting a sympathetic stress response, or indirectly, through inflammatory cytokines produced in the lungs and released into the circulation. METHODS AND RESULTS: This longitudinal study examined the association of particulates </=2.5 microm in diameter (PM(2.5)) with heart rate variability (HRV) in an occupational cohort (N=40). Continuous monitoring of exposure and HR was performed during and away from work. PM(2.5) levels were higher than ambient levels typically reported in Boston, 0.167+/-3.205 mg/m(3) (geometric mean+/-geometric SD). We found a 2.66% decrease (95% CI, -3.75% to -1.58%) in the 5-minute SD of normal RR intervals (SDNN) for every 1 mg/m(3) increase in the 4-hour moving PM(2.5) average and a 1.02% increase (95% CI, 0.59% to 1.46%) in HR after adjusting for potential confounding factors. The decrease in SDNN became larger as the averaging interval increased. CONCLUSIONS: Workers experienced altered cardiac autonomic control after exposure to occupational and environmental PM(2.5). There appears to be either a long-acting (several hours) and a short-acting (several minutes) component to the mechanism of action that may be related to the production of cytokines and the sympathetic stress response, respectively, or a cumulative effect that begins shortly after exposure begins. The clinical significance of these effects in a healthy working population is unclear.

Adult↗
PubMed2001

Sperm function and production of bovine embryos in vitro after swim-up with different calcium and caffeine concentration.

Frozen semen from bulls was used in artificial insemination programs was submitted to swim-up in Sperm Talp media containing different calcium (1.8, 2.6, 3.6 mM) or caffeine (2.5, 5.0, 7.5 microM) concentrations. The following sperm variables were evaluated: sperm recovery, motility, vigor, morphology, alterations in the pattern of capacitation by chlortetracycline (CTC) staining, and alterations in lysophosphatidyl choline (LPC)-induced acrosome reaction (AR). Sperm obtained from swim-up under different conditions were also tested for in vitro embryo production. No significant differences in the variables motility, vigor, morphology, and LPC-induced AR were observed among the treatments. However, the use of caffeine resulted in greater frequency of sperm with the capacitated pattern by CTC staining, compared to controls without caffeine. The greatest frequency of capacitated sperm (53%) was observed with 7.5 microM caffeine. Different calcium and caffeine concentrations in swim-up resulted in no significant differences in the cleavage rate and embryo development. In summary, micromolar concentrations of caffeine in Sperm Talp may stimulate sperm capacitation.

Acrosome Reaction↗