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Papers by Michael Hannigan

Research paper thumbnail of Impact of natural soiling on the transmission of PV cover plates

2013 IEEE 39th Photovoltaic Specialists Conference (PVSC), 2013

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Research paper thumbnail of Impact of gas/particle partitioning of semivolatile organic compounds on source apportionment with positive matrix factorization

Environmental science & technology, Jan 19, 2014

To quantify and minimize the influence of gas/particle (G/P) partitioning on receptor-based sourc... more To quantify and minimize the influence of gas/particle (G/P) partitioning on receptor-based source apportionment using particle-phase semivolatile organic compound (SVOC) data, positive matrix factorization (PMF) coupled with a bootstrap technique was applied to three data sets mainly composed of "measured-total" (measured particle- + gas-phase), "particle-only" (measured particle-phase) and "predicted-total" (measured particle-phase + predicted gas-phase) SVOCs to apportion carbonaceous aerosols. Particle- (PM2.5) and gas-phase SVOCs were collected using quartz fiber filters followed by PUF/XAD-4/PUF adsorbents and measured using gas chromatography-mass spectrometry (GC-MS). Concentrations of gas-phase SVOCs were also predicted from their particle-phase concentrations using absorptive partitioning theory. Five factors were resolved for each data set, and the factor profiles were generally consistent across the three PMF solutions. Using a previous sour...

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Research paper thumbnail of Crisis Intervention

The Professional Protection Officer, 2010

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Research paper thumbnail of Errors in coarse particulate matter mass concentrations and spatiotemporal characteristics when using subtraction estimation methods

Journal of the Air & Waste Management Association, 2013

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Research paper thumbnail of Intra-urban spatial variability and uncertainty assessment of PM2.5 sources based on carbonaceous species

Atmospheric Environment, 2012

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Research paper thumbnail of Positive matrix factorization of a 32-month series of daily PM2.5 speciation data with incorporation of temperature stratification

Atmospheric Environment, 2013

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Research paper thumbnail of Intra-urban spatial variability of PM2.5-bound carbonaceous components

Atmospheric Environment, 2012

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Research paper thumbnail of Characterization of organic aerosol in Big Bend National Park, Texas

Atmospheric Environment, 2002

... Steven G. Brown a , 1 , Pierre Herckes a , Lowell Ashbaugh b , Michael P. Hannigan a , 2 , So... more ... Steven G. Brown a , 1 , Pierre Herckes a , Lowell Ashbaugh b , Michael P. Hannigan a , 2 , Sonia M. Kreidenweis a and Jeffrey L ... The Big Bend Regional Aerosol and Visibility Observational (BRAVO) Study was conducted in Big Bend National Park, Texas, July through October ...

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Research paper thumbnail of Directional sensing requires G beta gamma-mediated PAK1 and PIX alpha-dependent activation of Cdc42

Cell, 2003

Efficient chemotaxis requires directional sensing and cell polarization. We describe a signaling ... more Efficient chemotaxis requires directional sensing and cell polarization. We describe a signaling mechanism involving G beta gamma, PAK-associated guanine nucleotide exchange factor (PIX alpha), Cdc42, and p21-activated kinase (PAK) 1. This pathway is utilized by chemoattractants to regulate directional sensing and directional migration of myeloid cells. Our results suggest that G beta gamma binds PAK1 and, via PAK-associated PIX alpha, activates Cdc42, which in turn activates PAK1. Thus, in this pathway, PAK1 is not only an effector for Cdc42, but it also functions as a scaffold protein required for Cdc42 activation. This G beta gamma-PAK1/PIX alpha/Cdc42 pathway is essential for the localization of F-actin formation to the leading edge, the exclusion of PTEN from the leading edge, directional sensing, and the persistent directional migration of chemotactic leukocytes. Although ligand-induced production of PIP(3) is not required for activation of this pathway, PIP(3) appears to localize the activation of Cdc42 by the pathway.

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Research paper thumbnail of Size distribution of trace organic species emitted from light-duty gasoline vehicles

Environmental science & technology, 2007

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Research paper thumbnail of Positive matrix factorization of PM(2.5): comparison and implications of using different speciation data sets

Environmental science & technology, 2012

To evaluate the utility and consistency of different speciation data sets in source apportionment... more To evaluate the utility and consistency of different speciation data sets in source apportionment of PM(2.5), positive matrix factorization (PMF) coupled with a bootstrap technique for uncertainty assessment was applied to four different 1-year data sets composed of bulk species, bulk species and water-soluble elements (WSE), bulk species and organic molecular markers (OMM), and all species. The five factors resolved by using only the bulk species best reproduced the observed concentrations of PM(2.5) components. Combining WSE with bulk species as PMF inputs also produced five factors. Three of them were linked to soil, road dust, and processed dust, and together contributed 26.0% of reconstructed PM(2.5) mass. A 7-factor PMF solution was identified using speciated OMM and bulk species. The EC/sterane and summertime/selective aliphatic factors had the highest contributions to EC (39.0%) and OC (53.8%), respectively. The nine factors resolved by including all species as input data are consistent with those from the previous two solutions (WSE and bulk species, OMM and bulk species) in both factor profiles and contributions (r = 0.88-1.00). The comparisons across different solutions indicate that the selection of input data set may depend on the PM components or sources of interest for specific source-oriented health study.

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Research paper thumbnail of The temporal lag structure of short-term associations of fine particulate matter chemical constituents and cardiovascular and respiratory hospitalizations

Environmental health perspectives, 2012

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Research paper thumbnail of Binge toluene exposure in pregnancy and pre-weaning developmental consequences in rats

Neurotoxicology and teratology, 2013

We modeled binge patterns of high-dose toluene abuse during gestation in rats.We examined the beh... more We modeled binge patterns of high-dose toluene abuse during gestation in rats.We examined the behavioral and morphological impact of prenatal toluene in offspring.Toluene caused poor perinatal outcome, malformations and neonatal death.Results suggest that gestational toluene abuse may yield similar outcomes in humans.Binge Toluene Exposure in Pregnancy and Pre-weaning Developmental Consequences in Rats. Bowen, S.E. and Hannigan, J.H. The persistent rate of abuse of inhaled organic solvents, especially among women of child-bearing age, raises the risk for teratogenic effects of maternal toluene abuse. In this study, timed-pregnant Sprague Dawley rats were exposed from Gestation Day (GD) 8 to GD20 to 12,000 or 8000 parts per million (ppm) toluene, or 0 ppm (controls) for 30 min twice daily, 60 min total daily exposure. Pups were assessed from postnatal day (PN) 4 to PN21 using a developmental battery measuring growth (i.e., body weight), maturational milestones (e.g., eye opening & incisor eruption), and biobehavioral development (e.g., negative geotaxis & surface righting). Pups exposed in utero to 12,000 ppm or 8000 ppm toluene weighed significantly less than the non-exposed control pups beginning at PN4 and PN12 (respectively) until PN21. Toluene resulted in significant increases in an index of poor perinatal outcome, specifically a composite of malformations, defined “runting” and neonatal death. No significant delays were observed in reaching maturational milestones. The results reveal that brief, repeated, prenatal exposure to high concentrations of toluene can cause growth retardation and malformations in rats. A comparison of the present, conservative results with findings in previous studies implies that binge patterns of toluene exposure in pregnant rats modeling human solvent abuse can result in developmental and morphological deficits in offspring. These results do not exclude the possibility that maternal toxicity as well as teratogenic effects of toluene may contribute to outcomes. The results suggest that abuse of inhaled organic solvents like toluene may result in similar early developmental outcomes in humans.

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Research paper thumbnail of Statistical methodology in oral and dental research: Pitfalls and recommendations

Journal of dentistry, 2013

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Research paper thumbnail of New roles for nurses as approved mental health professionals in England and Wales: A discussion paper

International journal of nursing studies, 2013

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Research paper thumbnail of Independent and conjoint associations of gout and hyperuricaemia with total and cardiovascular mortality

QJM : monthly journal of the Association of Physicians, 2013

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Research paper thumbnail of The sensitivity of health effect estimates from time-series studies to fine particulate matter component sampling schedule

Journal of exposure science & environmental epidemiology, 2013

The US Environmental Protection Agency air pollution monitoring data have been a valuable resourc... more The US Environmental Protection Agency air pollution monitoring data have been a valuable resource commonly used for investigating the associations between short-term exposures to PM2.5 chemical components and human health. However, the temporally sparse sampling on every third or sixth day may affect health effect estimation. We examined the impact of non-daily monitoring data on health effect estimates using daily data from the Denver Aerosol Sources and Health (DASH) study. Daily concentrations of four PM2.5 chemical components (elemental and organic carbon, sulfate, and nitrate) and hospital admission counts from 2003 through 2007 were used. Three every-third-day time series were created from the daily DASH monitoring data, imitating the US Speciation Trend Network (STN) monitoring schedule. A fourth, partly irregular, every-third-day time series was created by matching existing sampling days at a nearby STN monitor. Relative risks (RRs) of hospital admissions for PM2.5 components at lags 0-3 were estimated for each data set, adjusting for temperature, relative humidity, longer term temporal trends, and day of week using generalized additive models, and compared across different sampling schedules. The estimated RRs varied somewhat between the non-daily and daily sampling schedules and between the four non-daily schedules, and in some instances could lead to different conclusions. It was not evident which features of the data or analysis were responsible for the variation in effect estimates, although seeing similar variability in resampled data sets with relaxation of the every-third-day constraint suggests that limited power may have had a role. The use of non-daily monitoring data can influence interpretation of estimated effects of PM2.5 components on hospital admissions in time-series studies.

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Research paper thumbnail of Contrast and correlations between coarse and fine particulate matter in the United States

The Science of the total environment, 2013

PM10–2.5 is more variable than PM2.5, acting as the major driver for PM10 extremes.Either PM10–2.... more PM10–2.5 is more variable than PM2.5, acting as the major driver for PM10 extremes.Either PM10–2.5 or PM2.5 can be the major driver for mean PM10 depending on site.Harvest and planting affect PM10–2.5, but do not have a strong influence on PM2.5.Year-specific data of agricultural activities are essential for emission estimates.PM10–2.5 and PM2.5 from traffic sources seem to be emitted by different processes.The characteristics of concentrations of PM10–2.5, PM2.5, and PM10 at 77 sites in the United States are evaluated. PM10 concentrations show strong spatial variability, with highest levels occurring in the southwestern United States, driven primarily by PM10–2.5. PM10–2.5 and PM2.5 concentrations show different spatial patterns. The highest concentrations of PM10–2.5 were observed at sites in the southwestern US, leading to the highest PM10 concentrations there. The PM2.5 concentrations are the major contributors to the average PM10 concentrations at many sites in the eastern United States. Poor correlations were generally found between PM10–2.5 and PM2.5, suggesting that PM10–2.5 and PM2.5 are generally influenced by different sources. PM10–2.5 is generally more variable than PM2.5 because PM10–2.5 has a higher deposition velocity and is primarily emitted from mechanical processes (e.g. agricultural harvest and construction) that are more influenced by factors including human operation and wind speed leading to a strong episodic nature. As a result of its high variability, PM10–2.5 acts as the major driver for PM10 extremes. PM10–2.5 is significantly correlated with PM10 at all investigated sites, with the average correlation value R2 = 0.79. Correlations of PM2.5 with PM10 (average of 0.37) are overall considerably lower than those between PM10–2.5 and PM10. Different seasonal, weekly, and diurnal patterns were observed between PM10–2.5 and PM2.5 at agricultural, on-road traffic, quarrying, airport, and marine sites. At investigated agricultural sites, while the concentrations of PM2.5 are higher in winter when there are few agricultural activities, PM10–2.5 concentrations are lower in winter months than in summer and autumn months, with highest levels corresponding to harvest and planting. The harvest and planting signatures were not observed in PM2.5 concentrations at any of these sites, suggesting that agricultural activities do not have a strong influence on PM2.5 concentrations.

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Research paper thumbnail of Gestational toluene exposure effects on spontaneous and amphetamine-induced locomotor behavior in rats

Neurotoxicology and Teratology, 2007

Gestational Toluene Exposure Effects on Spontaneous and Amphetamine-Induced Locomotor Behavior in... more Gestational Toluene Exposure Effects on Spontaneous and Amphetamine-Induced Locomotor Behavior in Rats. Bowen, S.E., Mohammadi, M.H., Batis, J.C., and Hannigan, J.H. Neurotoxicology and Teratology, XX, 2006. The abuse of volatile organic solvents (inhalants) continues to be a major health concern throughout the world. Toluene, which is found in many products such as glues and household cleaners, is among the most commonly abused organic solvents. The neurobehavioral teratogenic sequelae of solvent abuse (i.e., repeated, brief inhalation exposures to very high concentrations of solvents) have not been examined thoroughly. In a preclinical model of inhalant abuse, timed-pregnant Sprague-Dawley rats were exposed to 0, 8000, or 12,000 parts per million (ppm) for 15 min twice daily from gestation day 8 (GD8) through GD20. In the first experiment, separate groups of offspring were observed individually in an open-field on postnatal day 22 (PN22), PN42 or PN63. In the second experiment, other offspring given identical prenatal toluene exposures were observed in an “open-field” following an acute i.p. injection of amphetamine (0, 0.56, 1.78 mg/kg) on PN28. Automated measurements of distance traveled and ambulatory time were recorded. Prenatal toluene exposure resulted in small alterations in spontaneous activity compared to non-exposed rats. Prenatal exposure to 12,000 ppm toluene resulted in significant hyposensitivity to the locomotor stimulatory effects of the amphetamine challenge in male but not female rats on PN28. The results demonstrate that prenatal exposure to abuse patterns of high concentrations of toluene through inhalation can alter spontaneous and amphetamine-induced locomotor behavior in rats. The expression of these effects also appears to depend upon the postnatal age of testing. These results imply that abuse of organic solvents during pregnancy in humans may also produce long-lasting effects on biobehavioral development.

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Research paper thumbnail of Detection of integrin-linked kinase in the serum of patients with malignant pleural mesothelioma

Journal of Thoracic and Cardiovascular Surgery, 2011

Integrin-linked kinase, which is relevant to neoplastic transformation, is highly expressed in ma... more Integrin-linked kinase, which is relevant to neoplastic transformation, is highly expressed in malignant pleural mesothelioma. Recently, detection of integrin-linked kinase in serum of patients with ovarian cancer has been reported. This study asks whether integrin-linked kinase can also be detected in serum of patients with malignant pleural mesothelioma and whether serum level has diagnostic or prognostic relevance for that disease.A sandwich enzyme-linked immunosorbent assay was designed to detect integrin-linked kinase and applied to serum samples from 46 patients with malignant pleural mesothelioma, 98 patients with other malignant chest disease, and 23 patients with benign chest disease. Integrin-linked kinase serum concentration and clinical data were correlated statistically.Median serum integrin-linked kinase concentration was significantly higher in malignant pleural mesothelioma (8.89 ng/mL) than in other malignant chest disease (0.66 ng/mL) or benign chest disease (0.78 ng/mL, P < .001). There was no relevant correlation of serum integrin-linked kinase with cell lysis parameters (R2 < 0.1). Serum integrin-linked kinase concentration greater than 2.48 ng/mL had diagnostic sensitivity of 80%, specificity of 95%, positive predictive value of 85.7%, negative predictive value of 92.7%, and overall accuracy of 91% for distinction between malignant pleural mesothelioma and other diseases. Serum integrin-linked kinase concentration in malignant pleural mesothelioma was independent of histologic subtype or asbestos exposure. There was no statistically significant impact of serum integrin-linked kinase concentration on prognosis.Integrin-linked kinase can be detected in serum of patients with malignant pleural mesothelioma and may be a diagnostic marker for the disease.

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Research paper thumbnail of Impact of natural soiling on the transmission of PV cover plates

2013 IEEE 39th Photovoltaic Specialists Conference (PVSC), 2013

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Research paper thumbnail of Impact of gas/particle partitioning of semivolatile organic compounds on source apportionment with positive matrix factorization

Environmental science & technology, Jan 19, 2014

To quantify and minimize the influence of gas/particle (G/P) partitioning on receptor-based sourc... more To quantify and minimize the influence of gas/particle (G/P) partitioning on receptor-based source apportionment using particle-phase semivolatile organic compound (SVOC) data, positive matrix factorization (PMF) coupled with a bootstrap technique was applied to three data sets mainly composed of "measured-total" (measured particle- + gas-phase), "particle-only" (measured particle-phase) and "predicted-total" (measured particle-phase + predicted gas-phase) SVOCs to apportion carbonaceous aerosols. Particle- (PM2.5) and gas-phase SVOCs were collected using quartz fiber filters followed by PUF/XAD-4/PUF adsorbents and measured using gas chromatography-mass spectrometry (GC-MS). Concentrations of gas-phase SVOCs were also predicted from their particle-phase concentrations using absorptive partitioning theory. Five factors were resolved for each data set, and the factor profiles were generally consistent across the three PMF solutions. Using a previous sour...

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Research paper thumbnail of Crisis Intervention

The Professional Protection Officer, 2010

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Research paper thumbnail of Errors in coarse particulate matter mass concentrations and spatiotemporal characteristics when using subtraction estimation methods

Journal of the Air & Waste Management Association, 2013

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Intra-urban spatial variability and uncertainty assessment of PM2.5 sources based on carbonaceous species

Atmospheric Environment, 2012

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Research paper thumbnail of Positive matrix factorization of a 32-month series of daily PM2.5 speciation data with incorporation of temperature stratification

Atmospheric Environment, 2013

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Research paper thumbnail of Intra-urban spatial variability of PM2.5-bound carbonaceous components

Atmospheric Environment, 2012

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Research paper thumbnail of Characterization of organic aerosol in Big Bend National Park, Texas

Atmospheric Environment, 2002

... Steven G. Brown a , 1 , Pierre Herckes a , Lowell Ashbaugh b , Michael P. Hannigan a , 2 , So... more ... Steven G. Brown a , 1 , Pierre Herckes a , Lowell Ashbaugh b , Michael P. Hannigan a , 2 , Sonia M. Kreidenweis a and Jeffrey L ... The Big Bend Regional Aerosol and Visibility Observational (BRAVO) Study was conducted in Big Bend National Park, Texas, July through October ...

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Research paper thumbnail of Directional sensing requires G beta gamma-mediated PAK1 and PIX alpha-dependent activation of Cdc42

Cell, 2003

Efficient chemotaxis requires directional sensing and cell polarization. We describe a signaling ... more Efficient chemotaxis requires directional sensing and cell polarization. We describe a signaling mechanism involving G beta gamma, PAK-associated guanine nucleotide exchange factor (PIX alpha), Cdc42, and p21-activated kinase (PAK) 1. This pathway is utilized by chemoattractants to regulate directional sensing and directional migration of myeloid cells. Our results suggest that G beta gamma binds PAK1 and, via PAK-associated PIX alpha, activates Cdc42, which in turn activates PAK1. Thus, in this pathway, PAK1 is not only an effector for Cdc42, but it also functions as a scaffold protein required for Cdc42 activation. This G beta gamma-PAK1/PIX alpha/Cdc42 pathway is essential for the localization of F-actin formation to the leading edge, the exclusion of PTEN from the leading edge, directional sensing, and the persistent directional migration of chemotactic leukocytes. Although ligand-induced production of PIP(3) is not required for activation of this pathway, PIP(3) appears to localize the activation of Cdc42 by the pathway.

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Research paper thumbnail of Size distribution of trace organic species emitted from light-duty gasoline vehicles

Environmental science & technology, 2007

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Research paper thumbnail of Positive matrix factorization of PM(2.5): comparison and implications of using different speciation data sets

Environmental science & technology, 2012

To evaluate the utility and consistency of different speciation data sets in source apportionment... more To evaluate the utility and consistency of different speciation data sets in source apportionment of PM(2.5), positive matrix factorization (PMF) coupled with a bootstrap technique for uncertainty assessment was applied to four different 1-year data sets composed of bulk species, bulk species and water-soluble elements (WSE), bulk species and organic molecular markers (OMM), and all species. The five factors resolved by using only the bulk species best reproduced the observed concentrations of PM(2.5) components. Combining WSE with bulk species as PMF inputs also produced five factors. Three of them were linked to soil, road dust, and processed dust, and together contributed 26.0% of reconstructed PM(2.5) mass. A 7-factor PMF solution was identified using speciated OMM and bulk species. The EC/sterane and summertime/selective aliphatic factors had the highest contributions to EC (39.0%) and OC (53.8%), respectively. The nine factors resolved by including all species as input data are consistent with those from the previous two solutions (WSE and bulk species, OMM and bulk species) in both factor profiles and contributions (r = 0.88-1.00). The comparisons across different solutions indicate that the selection of input data set may depend on the PM components or sources of interest for specific source-oriented health study.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The temporal lag structure of short-term associations of fine particulate matter chemical constituents and cardiovascular and respiratory hospitalizations

Environmental health perspectives, 2012

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Research paper thumbnail of Binge toluene exposure in pregnancy and pre-weaning developmental consequences in rats

Neurotoxicology and teratology, 2013

We modeled binge patterns of high-dose toluene abuse during gestation in rats.We examined the beh... more We modeled binge patterns of high-dose toluene abuse during gestation in rats.We examined the behavioral and morphological impact of prenatal toluene in offspring.Toluene caused poor perinatal outcome, malformations and neonatal death.Results suggest that gestational toluene abuse may yield similar outcomes in humans.Binge Toluene Exposure in Pregnancy and Pre-weaning Developmental Consequences in Rats. Bowen, S.E. and Hannigan, J.H. The persistent rate of abuse of inhaled organic solvents, especially among women of child-bearing age, raises the risk for teratogenic effects of maternal toluene abuse. In this study, timed-pregnant Sprague Dawley rats were exposed from Gestation Day (GD) 8 to GD20 to 12,000 or 8000 parts per million (ppm) toluene, or 0 ppm (controls) for 30 min twice daily, 60 min total daily exposure. Pups were assessed from postnatal day (PN) 4 to PN21 using a developmental battery measuring growth (i.e., body weight), maturational milestones (e.g., eye opening & incisor eruption), and biobehavioral development (e.g., negative geotaxis & surface righting). Pups exposed in utero to 12,000 ppm or 8000 ppm toluene weighed significantly less than the non-exposed control pups beginning at PN4 and PN12 (respectively) until PN21. Toluene resulted in significant increases in an index of poor perinatal outcome, specifically a composite of malformations, defined “runting” and neonatal death. No significant delays were observed in reaching maturational milestones. The results reveal that brief, repeated, prenatal exposure to high concentrations of toluene can cause growth retardation and malformations in rats. A comparison of the present, conservative results with findings in previous studies implies that binge patterns of toluene exposure in pregnant rats modeling human solvent abuse can result in developmental and morphological deficits in offspring. These results do not exclude the possibility that maternal toxicity as well as teratogenic effects of toluene may contribute to outcomes. The results suggest that abuse of inhaled organic solvents like toluene may result in similar early developmental outcomes in humans.

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Research paper thumbnail of Statistical methodology in oral and dental research: Pitfalls and recommendations

Journal of dentistry, 2013

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Research paper thumbnail of New roles for nurses as approved mental health professionals in England and Wales: A discussion paper

International journal of nursing studies, 2013

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Independent and conjoint associations of gout and hyperuricaemia with total and cardiovascular mortality

QJM : monthly journal of the Association of Physicians, 2013

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The sensitivity of health effect estimates from time-series studies to fine particulate matter component sampling schedule

Journal of exposure science & environmental epidemiology, 2013

The US Environmental Protection Agency air pollution monitoring data have been a valuable resourc... more The US Environmental Protection Agency air pollution monitoring data have been a valuable resource commonly used for investigating the associations between short-term exposures to PM2.5 chemical components and human health. However, the temporally sparse sampling on every third or sixth day may affect health effect estimation. We examined the impact of non-daily monitoring data on health effect estimates using daily data from the Denver Aerosol Sources and Health (DASH) study. Daily concentrations of four PM2.5 chemical components (elemental and organic carbon, sulfate, and nitrate) and hospital admission counts from 2003 through 2007 were used. Three every-third-day time series were created from the daily DASH monitoring data, imitating the US Speciation Trend Network (STN) monitoring schedule. A fourth, partly irregular, every-third-day time series was created by matching existing sampling days at a nearby STN monitor. Relative risks (RRs) of hospital admissions for PM2.5 components at lags 0-3 were estimated for each data set, adjusting for temperature, relative humidity, longer term temporal trends, and day of week using generalized additive models, and compared across different sampling schedules. The estimated RRs varied somewhat between the non-daily and daily sampling schedules and between the four non-daily schedules, and in some instances could lead to different conclusions. It was not evident which features of the data or analysis were responsible for the variation in effect estimates, although seeing similar variability in resampled data sets with relaxation of the every-third-day constraint suggests that limited power may have had a role. The use of non-daily monitoring data can influence interpretation of estimated effects of PM2.5 components on hospital admissions in time-series studies.

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Research paper thumbnail of Contrast and correlations between coarse and fine particulate matter in the United States

The Science of the total environment, 2013

PM10–2.5 is more variable than PM2.5, acting as the major driver for PM10 extremes.Either PM10–2.... more PM10–2.5 is more variable than PM2.5, acting as the major driver for PM10 extremes.Either PM10–2.5 or PM2.5 can be the major driver for mean PM10 depending on site.Harvest and planting affect PM10–2.5, but do not have a strong influence on PM2.5.Year-specific data of agricultural activities are essential for emission estimates.PM10–2.5 and PM2.5 from traffic sources seem to be emitted by different processes.The characteristics of concentrations of PM10–2.5, PM2.5, and PM10 at 77 sites in the United States are evaluated. PM10 concentrations show strong spatial variability, with highest levels occurring in the southwestern United States, driven primarily by PM10–2.5. PM10–2.5 and PM2.5 concentrations show different spatial patterns. The highest concentrations of PM10–2.5 were observed at sites in the southwestern US, leading to the highest PM10 concentrations there. The PM2.5 concentrations are the major contributors to the average PM10 concentrations at many sites in the eastern United States. Poor correlations were generally found between PM10–2.5 and PM2.5, suggesting that PM10–2.5 and PM2.5 are generally influenced by different sources. PM10–2.5 is generally more variable than PM2.5 because PM10–2.5 has a higher deposition velocity and is primarily emitted from mechanical processes (e.g. agricultural harvest and construction) that are more influenced by factors including human operation and wind speed leading to a strong episodic nature. As a result of its high variability, PM10–2.5 acts as the major driver for PM10 extremes. PM10–2.5 is significantly correlated with PM10 at all investigated sites, with the average correlation value R2 = 0.79. Correlations of PM2.5 with PM10 (average of 0.37) are overall considerably lower than those between PM10–2.5 and PM10. Different seasonal, weekly, and diurnal patterns were observed between PM10–2.5 and PM2.5 at agricultural, on-road traffic, quarrying, airport, and marine sites. At investigated agricultural sites, while the concentrations of PM2.5 are higher in winter when there are few agricultural activities, PM10–2.5 concentrations are lower in winter months than in summer and autumn months, with highest levels corresponding to harvest and planting. The harvest and planting signatures were not observed in PM2.5 concentrations at any of these sites, suggesting that agricultural activities do not have a strong influence on PM2.5 concentrations.

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Research paper thumbnail of Gestational toluene exposure effects on spontaneous and amphetamine-induced locomotor behavior in rats

Neurotoxicology and Teratology, 2007

Gestational Toluene Exposure Effects on Spontaneous and Amphetamine-Induced Locomotor Behavior in... more Gestational Toluene Exposure Effects on Spontaneous and Amphetamine-Induced Locomotor Behavior in Rats. Bowen, S.E., Mohammadi, M.H., Batis, J.C., and Hannigan, J.H. Neurotoxicology and Teratology, XX, 2006. The abuse of volatile organic solvents (inhalants) continues to be a major health concern throughout the world. Toluene, which is found in many products such as glues and household cleaners, is among the most commonly abused organic solvents. The neurobehavioral teratogenic sequelae of solvent abuse (i.e., repeated, brief inhalation exposures to very high concentrations of solvents) have not been examined thoroughly. In a preclinical model of inhalant abuse, timed-pregnant Sprague-Dawley rats were exposed to 0, 8000, or 12,000 parts per million (ppm) for 15 min twice daily from gestation day 8 (GD8) through GD20. In the first experiment, separate groups of offspring were observed individually in an open-field on postnatal day 22 (PN22), PN42 or PN63. In the second experiment, other offspring given identical prenatal toluene exposures were observed in an “open-field” following an acute i.p. injection of amphetamine (0, 0.56, 1.78 mg/kg) on PN28. Automated measurements of distance traveled and ambulatory time were recorded. Prenatal toluene exposure resulted in small alterations in spontaneous activity compared to non-exposed rats. Prenatal exposure to 12,000 ppm toluene resulted in significant hyposensitivity to the locomotor stimulatory effects of the amphetamine challenge in male but not female rats on PN28. The results demonstrate that prenatal exposure to abuse patterns of high concentrations of toluene through inhalation can alter spontaneous and amphetamine-induced locomotor behavior in rats. The expression of these effects also appears to depend upon the postnatal age of testing. These results imply that abuse of organic solvents during pregnancy in humans may also produce long-lasting effects on biobehavioral development.

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Research paper thumbnail of Detection of integrin-linked kinase in the serum of patients with malignant pleural mesothelioma

Journal of Thoracic and Cardiovascular Surgery, 2011

Integrin-linked kinase, which is relevant to neoplastic transformation, is highly expressed in ma... more Integrin-linked kinase, which is relevant to neoplastic transformation, is highly expressed in malignant pleural mesothelioma. Recently, detection of integrin-linked kinase in serum of patients with ovarian cancer has been reported. This study asks whether integrin-linked kinase can also be detected in serum of patients with malignant pleural mesothelioma and whether serum level has diagnostic or prognostic relevance for that disease.A sandwich enzyme-linked immunosorbent assay was designed to detect integrin-linked kinase and applied to serum samples from 46 patients with malignant pleural mesothelioma, 98 patients with other malignant chest disease, and 23 patients with benign chest disease. Integrin-linked kinase serum concentration and clinical data were correlated statistically.Median serum integrin-linked kinase concentration was significantly higher in malignant pleural mesothelioma (8.89 ng/mL) than in other malignant chest disease (0.66 ng/mL) or benign chest disease (0.78 ng/mL, P < .001). There was no relevant correlation of serum integrin-linked kinase with cell lysis parameters (R2 < 0.1). Serum integrin-linked kinase concentration greater than 2.48 ng/mL had diagnostic sensitivity of 80%, specificity of 95%, positive predictive value of 85.7%, negative predictive value of 92.7%, and overall accuracy of 91% for distinction between malignant pleural mesothelioma and other diseases. Serum integrin-linked kinase concentration in malignant pleural mesothelioma was independent of histologic subtype or asbestos exposure. There was no statistically significant impact of serum integrin-linked kinase concentration on prognosis.Integrin-linked kinase can be detected in serum of patients with malignant pleural mesothelioma and may be a diagnostic marker for the disease.

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