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Sample records for acid exposure time

  1. Factors affecting the response of lung clearance systems to acid aerosols: role of exposure concentration, exposure time, and relative acidity.

    PubMed

    Schlesinger, R B

    1989-02-01

    The ability of the lungs to clear deposited material is essential for maintenance of lung homeostasis. Acid aerosols have been shown to alter the efficiency of this process. This paper assesses the role of acid aerosol exposure concentration (C), exposure time (T), and relative acidity in producing changes in clearance from both the tracheobronchial tree and respiratory region of the lungs of rabbits. The response was found to be due to total exposure, i.e., some combination form of C x T, and was also related to relative acidity.

  2. Color Stability of Enamel following Different Acid Etching and Color Exposure Times

    PubMed Central

    Jahanbin, Arezoo; Basafa, Mohammad; Moazzami, Mostafa; Basafa, Behnoush; Eslami, Neda

    2014-01-01

    Background and aims. The aim of this study was to evaluate the effect of different etching times on enamel color stability after immediate versus delayed exposure to colored artificial saliva (CAS). Materials and methods. Human first premolars were divided into five groups of twenty. A colorimeter was used according to the CIE system on the mid-buccal and mid-lingual surfaces to evaluate initial tooth color. Samples in group A remained unetched. In groups B to E, buccal and lingual surfaces were initially etched with phosphoric acid for 15 and 60 seconds, respectively. Then, the samples in groups A and C were immersed in colored artificial saliva (cola+saliva). In group B, the teeth were immersed in simple artificial saliva (AS). Samples in groups D and E were immersed in AS for 24 and 72 hours, respectively before being immersed in colored AS. The teeth were immersed for one month in each solution before color measurement. During the test period, the teeth were retrieved from the staining solution and stored in AS for five minutes. This was repeated 60 times. Color changes of buccal and lingual surfaces were calculated. Kruskal-Wallis and Wilcoxon tests were used for statistical analysis (α ≤0.05). Results. There were no significant differences between the groups in term of ΔE of buccal (P = 0.148) and lingual surfaces (P = 0.73). Conclusion. Extended time of etching did not result in significant enamel color change. Immediate and delayed exposure of etched enamel to staining solutions did not result in clinically detectable tooth color changes. PMID:25093048

  3. Copper corrosion mechanism in the presence of formic acid vapor for short exposure times

    SciTech Connect

    Bastidas, J.M.; Lopez-Delgado, A.; Cano, E.; Polo, J.L.; Lopez, F.A.

    2000-03-01

    The rate of copper corrosion originated by the action of formic acid vapors at 100% relative humidity was studied. Five formic vapor concentration levels (10, 50, 100, 200, and 300 ppm) were used. A copper corrosion rate of up to 1,300 mg/m{sup 2} d was measured for a period of 21 days using a gravimetric method. The patina layers were characterized using cathodic reduction, X-ray powder diffraction. Fourier transform infrared spectrometry, and scanning electron microscopy techniques. Some of the components identified in the corrosion-product layers were cuprite (Cu{sub 2}O), cupric hydroxide hydrate [Cu(OH){sub 2}{sm_bullet}H{sub 2}O], and copper formate hydrate [Cu(HCOO){sub 2}{sm_bullet}4H{sub 2}O]. The latter was formed by both cupric hydroxide and formic acid-cuprous ion complex mechanisms.

  4. Steering the efficiency of carbon nanotube-silicon photovoltaic cells by acid vapor exposure: a real-time spectroscopic tracking.

    PubMed

    Pintossi, C; Pagliara, S; Drera, G; De Nicola, F; Castrucci, P; De Crescenzi, M; Crivellari, M; Boscardin, M; Sangaletti, L

    2015-05-13

    Hybrid carbon nanotube-silicon (CNT-Si) junctions have been investigated by angle resolved photoemission spectroscopy (AR-XPS) with the aim to clarify the effects of a nonstoichiometric silicon oxide buried interface on the overall cell efficiency. A complex silicon oxide interface has been clearly identified and its origin and role in the heterojunction have been probed by exposing the cells to hydrofluoric (HF) and nitric (HNO3) acid. Real-time monitoring of the cell efficiencies during the steps following acid exposure (up to 1 week after etching) revealed a correlation between the thickness and chemical state of the oxide layer and the cell efficiencies. By matching the AR-XPS and Raman spectroscopy with the electrical response data it has been possible to discriminate the effects on the cell efficiency of the buried SiO(x) interface from those related to CNT acid doping. The overall cell behavior recorded for different thicknesses of the SiO(x) interface indicates that the buried oxide layer is likely acting as a passivating/inversion layer in a metal-insulator-semiconductor junction.

  5. Exposures to acidic aerosols.

    PubMed

    Spengler, J D; Keeler, G J; Koutrakis, P; Ryan, P B; Raizenne, M; Franklin, C A

    1989-02-01

    Ambient monitoring of acid aerosols in four U.S. cities and in a rural region of southern Ontario clearly show distinct periods of strong acidity. Measurements made in Kingston, TN, and Steubenville, OH, resulted in 24-hr H+ ion concentrations exceeding 100 nmole/m3 more than 10 times during summer months. Periods of elevated acidic aerosols occur less frequently in winter months. The H+ determined during episodic conditions in southern Ontario indicates that respiratory tract deposition can exceed the effects level reported in clinical studies. Observed 12-hr H+ concentrations exceeded 550 nmole/m3 (approximately 27 micrograms/m3 H2SO4). The maximum estimated 1-hr concentration exceeded 1500 nmole/m3 for H+ ions. At these concentrations, an active child might receive more than 2000 nmole of H+ ion in 12 hr and in excess of 900 nmole during the hour when H2SO4 exceeded 50 micrograms/m3.

  6. Acidic sulfate aerosols: characterization and exposure.

    PubMed

    Lioy, P J; Waldman, J M

    1989-02-01

    Exposures to acidic aerosol in the atmosphere are calculated from data reported in the scientific literature. The majority of date was not derived from studies necessarily designed to examine human exposures. Most of the studies were designed to investigate the characteristics of the atmosphere. However, the measurements were useful in defining two potential exposure situations: regional stagnation and transport conditions and local plume impacts. Levels of acidic aerosol in excess of 20 to 40 micrograms/m3 (as H2SO4) have been observed for time durations ranging from 1 to 12 hr. These were associated with high, but not necessarily the highest, atmospheric SO4(2)- levels. Exposures of 100 to 900 micrograms/m3/hr were calculated for the acid events that were monitored. In contrast, earlier London studies indicated that apparent acidity in excess of 100 micrograms/m3 (as H2SO4) was present in the atmosphere, and exposures less than 2000 micrograms/m3/hr were possible. Our present knowledge about the frequency, magnitude, and duration of acidic sulfate aerosol events and episodes is insufficient. Efforts must be made to gather more data, but these should be done in such a way that evaluation of human exposure is the focus of the research. In addition, further data are required on the mechanisms of formation of H2SO4 and on what factors can be used to predict acidic sulfate episodes.

  7. Acidic sulfate aerosols: characterization and exposure.

    PubMed Central

    Lioy, P J; Waldman, J M

    1989-01-01

    Exposures to acidic aerosol in the atmosphere are calculated from data reported in the scientific literature. The majority of date was not derived from studies necessarily designed to examine human exposures. Most of the studies were designed to investigate the characteristics of the atmosphere. However, the measurements were useful in defining two potential exposure situations: regional stagnation and transport conditions and local plume impacts. Levels of acidic aerosol in excess of 20 to 40 micrograms/m3 (as H2SO4) have been observed for time durations ranging from 1 to 12 hr. These were associated with high, but not necessarily the highest, atmospheric SO4(2)- levels. Exposures of 100 to 900 micrograms/m3/hr were calculated for the acid events that were monitored. In contrast, earlier London studies indicated that apparent acidity in excess of 100 micrograms/m3 (as H2SO4) was present in the atmosphere, and exposures less than 2000 micrograms/m3/hr were possible. Our present knowledge about the frequency, magnitude, and duration of acidic sulfate aerosol events and episodes is insufficient. Efforts must be made to gather more data, but these should be done in such a way that evaluation of human exposure is the focus of the research. In addition, further data are required on the mechanisms of formation of H2SO4 and on what factors can be used to predict acidic sulfate episodes. PMID:2651103

  8. Acidic sulfate aerosols: characterization and exposure

    SciTech Connect

    Lioy, P.J.; Waldman, J.M.

    1989-02-01

    Exposures to acidic aerosol in the atmosphere are calculated from data reported in the scientific literature. The majority of date was not derived from studies necessarily designed to examine human exposures. Most of the studies were designed to investigate the characteristics of the atmosphere. However, the measurements were useful in defining two potential exposure situations: regional stagnation and transport conditions and local plume impacts. Levels of acidicaerosol in excess of 20 to 40 micrograms/m/sup 3/ (as H/sub 2/SO/sub 4/) have been observed for time durations ranging from 1 to 12 hr. These were associated with high, but not necessarily the highest, atmospheric SO/sub 4/(2)- levels. Exposures of 100 to 900 micrograms/m/sup 3//hr were calculated for the acid events that were monitored. In contrast, earlier London studies indicated that apparent acidity in excess of 100 micrograms/m/sup 3/ (as H/sub 2/SO/sub 4/) was present in the atmosphere, and exposures less than 2000 micrograms/m/sup 3//hr were possible. Our present knowledge about the frequency, magnitude, and duration of acidic sulfate aerosol events and episodes is insufficient. Efforts must be made to gather more data, but these should be done in such a way that evaluation of human exposure is the focus of the research. In addition, further data are required on the mechanisms of formation of H/sub 2/SO/sub 4/ and on what factors can be used to predict acidic sulfate episodes. 96 references.

  9. VITRIFICATION OF THAI NATIVE CATTLE OOCYTES: EFFECTS OF ETHYLENE GLYCOL CONCENTRATIONS AND EXPOSURE TIME, LINOLEIC ACID ALBUMIN AND CHOLESTEROL-LOADED METHYL-B-CYCLODEXTRIN.

    PubMed

    Chasombat, Jakkhaphan; Vongpralub, Thevin; Sirisathien, Saksiri; Phasuk, Yupin; Sonseeda, Pronjit

    2015-01-01

    The present study aimed to improve the oocyte vitrification procedure for preservation of Thai native cattle genetic resources. In Experiment I, oocytes were exposed to various doses (2%, 4% and 6%) of ethylene glycol (EG) in vitrification solution I (VS-I) for different equilibration times (10 or 20 min) before being exposed to VS-II and then subjected to vitrification. Experiment II was divided into two parts: (a) oocytes were matured in medium supplemented with linoleic acid albumin (LAA) (1% or 2%) and then vitrified; (b) matured oocytes were preincubated with cholesterol-loaded methyl-β-cyclodextrin (CLC) (1% or 2%) and then vitrified. Equilibration of oocytes by exposure to 6% EG in VS-I for 10 min (Experiment I), and in vitro maturation of immature oocytes in medium supplementation with 2% LAA (Experiment II) were the most effective methods; vitrified/thawed oocytes showed higher rates of survival and subsequent embryonic development compared with the other experimental groups. PMID:26510334

  10. Exposure to sulfuric acid in zinc production.

    PubMed

    Bråtveit, Magne; Haaland, Inger Margrethe; Moen, Bente E; Målsnes, Agnar

    2004-03-01

    This study characterized workers' exposure to sulfuric acid in two cell houses of a zinc production plant. We also aimed at estimating previous exposure to sulfuric acid by simulating the process conditions from before 1975 to produce exposure data for an epidemiological study on cancer in this industry. Further, we compared different sampling methods for aerosols in the cell houses. Personal sampling with a 37 mm Millipore cassette showed that the geometric means of the exposure levels for the workers in the two cell houses were 0.07 mg/m3 (range 0.01-0.48 mg/m3) and 0.04 mg/m3 (range 0.01-0.15 mg/m3). Norway's newly revised limit value of 0.1 mg/m3 was exceeded in 39.0 and 12.9% of the samples in the two cell houses. After the foam layer was removed from the electrolyte surface to simulate the production process from before 1975, the concentration of sulfuric acid increased from 0.11 to 6.04 mg/m3 in stationary measurement by the Millipore sampler. Stationary sampling showed that the Millipore sampler and the inhalable fraction of the Respicon impactor underestimated the sulfuric acid concentration by factors of 1.5 and 2.1 compared with the Institute of Occupational Medicine (IOM) sampler. Sampling with the Respicon impactor showed that the respirable, tracheobronchial and extrathoracic fractions constituted 3.0, 18.7 and 71.7% of the inhalable sulfuric acid aerosol, respectively. Today's exposure levels are lower than those reported to be associated with an increased prevalence of laryngeal cancer in other industries, but the levels prior to 1975 seem to have been much higher. By mass, most of the inhalable aerosol was in the size fractions considered to be highly relevant for the effects of sulfuric acid on the respiratory system. The risk of cancer among the cell house workers should be investigated in an epidemiological study.

  11. Pulmonary function and clearance after prolonged sulfuric acid aerosol exposure

    SciTech Connect

    Ives, P.J. ); Gerrity, T.R.; DeWitt, P.; Folinsbee, L.J. )

    1991-03-15

    The authors studied pulmonary function and clearance responses after a 4 H exposure to 75-100 {mu}g/m{sup 3} sulfuric acid aerosol (SAA). Healthy subjects, who exercised for 30 min/H at ventilation of about 25 L/min, were exposed once to clean air and once to SAA. Oral hygiene and acidic juice gargle were used to minimize oral ammonia. Lung function tests, including spirometry, plethysmography, and partial flow-volume (PEFV) curves were performed before and after exposure. Clearance of 99m-Technetium labeled iron oxide was assessed after each exposure. The first moment of fractional tracheobronchial retention (M1TBR), after correcting for 24 H retention and normalizing to time zero, was used as an index of clearance. There were no significant changes in lung volumes, airways resistance, or maximum expiratory flows after SAA exposure. Flow at 40% of total lung capacity on PEFV curves decreased 17% (NS) after SAA exposure. Tracheobronchial clearance was accelerated after a single exposure to SAA; M1TBR decreased from 73 {plus minus} 5 min (air) to 69 {plus minus} 5 min (SAA). These results suggest that acute prolonged exposure to low levels of SAA has minimal effects on lung mechanics in healthy subjects but does produce a modest acceleration of particle clearance.

  12. Real Time Radiation Exposure And Health Risks

    NASA Technical Reports Server (NTRS)

    Hu, Shaowen; Barzilla, Janet E.; Semones, Edward J.

    2015-01-01

    Radiation from solar particle events (SPEs) poses a serious threat to future manned missions outside of low Earth orbit (LEO). Accurate characterization of the radiation environment in the inner heliosphere and timely monitoring the health risks to crew are essential steps to ensure the safety of future Mars missions. In this project we plan to develop an approach that can use the particle data from multiple satellites and perform near real-time simulations of radiation exposure and health risks for various exposure scenarios. Time-course profiles of dose rates will be calculated with HZETRN and PDOSE from the energy spectrum and compositions of the particles archived from satellites, and will be validated from recent radiation exposure measurements in space. Real-time estimation of radiation risks will be investigated using ARRBOD. This cross discipline integrated approach can improve risk mitigation by providing critical information for risk assessment and medical guidance to crew during SPEs.

  13. Exposure influences expressive timing judgments in music.

    PubMed

    Honing, Henkjan; Ladinig, Olivia

    2009-02-01

    This study is concerned with the question whether, and to what extent, listeners' previous exposure to music in everyday life, and expertise as a result of formal musical training, play a role in making expressive timing judgments in music. This was investigated by using a Web-based listening experiment in which listeners with a wide range of musical backgrounds were asked to compare 2 recordings of the same composition (15 pairs, grouped in 3 musical genres), 1 of which was tempo-transformed (manipulating the expressive timing). The results show that expressive timing judgments are not so much influenced by expertise levels, as is suggested by the expertise hypothesis, but by exposure to a certain musical idiom, as is suggested by the exposure hypothesis. As such, the current study provides evidence for the idea that some musical capabilities are acquired through mere exposure to music, and that these abilities are more likely enhanced by active listening (exposure) than by formal musical training (expertise).

  14. Exposure assessment of oxidant gases and acidic aerosols

    SciTech Connect

    Lioy, P.J.

    1989-01-01

    Clearly the presence of high ozone and acidic species in North America is primarily dependent upon photochemical air pollution. Evidence shows, however, that high acid exposures may occur in specific types of areas of high sulfur fuel use during the winter. At the present time, our concerns about exposure to local populations and regional populations should be directed primarily toward the outdoor activity patterns of individuals in the summer, and how those activity patterns relate to the location, duration, and concentrations of ozone and acid aerosol in photochemical air pollution episodes. Lioy Dyba and Mage et al have examined the activity patterns of children in summer camps. Because they spend more time outside than the normal population, these children form an important group of exercising individuals subject to photochemical pollution exposures. The dose of ozone inhaled by the children in the two camps was within 50% and 25% of the dose inhaled by adults in controlled clinical situations that produced clinically significant decrements in pulmonary function and increased the symptoms after 6.6 hr exposure in a given day. The chamber studies have used only ozone, whereas in the environment this effect may be enhanced by the presence of a complex mixture. The work of Lioy et al in Mendham, New Jersey found that hydrogen ion seemed to play a role in the inability of the children to return immediately to their normal peak expiratory flow rate after exposure. The camp health study conducted in Dunsville, Ontario suggested that children participating in a summer camp where moderate levels of ozone (100 ppb) but high levels of acid (46 micrograms/m3) occurred during an episode had a similar response. Thus, for children or exercising adults who are outdoors for at least one hour or more during a given day, the presence and persistence of oxidants in the environment are of particular concern. 63 references.

  15. Exposure Influences Expressive Timing Judgments in Music

    ERIC Educational Resources Information Center

    Honing, Henkjan; Ladinig, Olivia

    2009-01-01

    This study is concerned with the question whether, and to what extent, listeners' previous exposure to music in everyday life, and expertise as a result of formal musical training, play a role in making expressive timing judgments in music. This was investigated by using a Web-based listening experiment in which listeners with a wide range of…

  16. Accelerated Fatigue of Dentin with Exposure to Lactic Acid

    PubMed Central

    Majd, H.; Ryou, H.; Mutluay, M. M.; Xu, Hockin H. K.; Arola, D.

    2013-01-01

    Composite restorations accumulate more biofilm than other dental materials. This increases the likelihood for the hard tissues supporting a restoration (i.e. dentin and enamel) to be exposed to acidic conditions beyond that resulting from dietary variations. In this investigation the fatigue strength and fatigue crack growth resistance of human coronal dentin were characterized within a lactic acid solution (with pH=5) and compared to that of controls evaluated in neutral conditions (pH=7). A comparison of the fatigue life distributions showed that the lactic acid exposure resulted in a significant reduction in the fatigue strength (p≤0.001), and nearly 30% reduction in the apparent endurance limit (from 44 MPa to 32 MPa). The reduction in pH also caused a significant decrease (p≤0.05) in the threshold stress intensity range required for the initiation of cyclic crack growth, and significant increase in the incremental rate of crack extension. Exposure of tooth structure to lactic acid may cause demineralization, but it also increases the likelihood of restored tooth failures via fatigue, and after short time periods. PMID:23948166

  17. Accelerated fatigue of dentin with exposure to lactic acid.

    PubMed

    Do, Dominic; Orrego, Santiago; Majd, Hessam; Ryou, Heonjune; Mutluay, Mustafa M; Xu, Hockin H K; Arola, Dwayne D

    2013-11-01

    Composite restorations accumulate more biofilm than other dental materials. This increases the likelihood for the hard tissues supporting a restoration (i.e. dentin and enamel) to be exposed to acidic conditions beyond that resulting from dietary variations. In this investigation the fatigue strength and fatigue crack growth resistance of human coronal dentin were characterized within a lactic acid solution (with pH = 5) and compared to that of controls evaluated in neutral conditions (pH = 7). A comparison of the fatigue life distributions showed that the lactic acid exposure resulted in a significant reduction in the fatigue strength (p ≤ 0.001), and nearly 30% reduction in the apparent endurance limit (from 44 MPa to 32 MPa). The reduction in pH also caused a significant decrease (p ≤ 0.05) in the threshold stress intensity range required for the initiation of cyclic crack growth, and significant increase in the incremental rate of crack extension. Exposure of tooth structure to lactic acid may cause demineralization, but it also increases the likelihood of restored tooth failures via fatigue, and after short time periods.

  18. Predicting survival time for cold exposure

    NASA Astrophysics Data System (ADS)

    Tikuisis, Peter

    1995-06-01

    The prediction of survival time (ST) for cold exposure is speculative as reliable controlled data of deep hypothermia are unavailable. At best, guidance can be obtained from case histories of accidental exposure. This study describes the development of a mathematical model for the prediction of ST under sedentary conditions in the cold. The model is based on steady-state heat conduction in a single cylinder comprised of a core and two concentric annular shells representing the fat plus skin and the clothing plus still boundary layer, respectively. The ambient condition can be either air or water; the distinction is made by assigning different values of insulation to the still boundary layer. Metabolic heat production ( M) is comprised of resting and shivering components with the latter predicted by temperature signals from the core and skin. Where the cold exposure is too severe for M to balance heat loss, ST is largely determined by the rate of heat loss from the body. Where a balance occurs, ST is governed by the endurance time for shivering. End of survival is marked by the deep core temperature reaching a value of 30° C. The model was calibrated against survival data of cold water (0 to 20° C) immersion and then applied to cold air exposure. A sampling of ST predictions for the nude exposure of an average healthy male in relatively calm air (1 km/h wind speed) are the following: 1.8, 2.5, 4.1, 9.0, and >24 h for -30, -20, -10, 0, and 10° C, respectively. With two layers of loose clothing (average thickness of 1 mm each) in a 5 km/h wind, STs are 4.0, 5.6, 8.6, 15.4, and >24 h for -50, -40, -30, -20, and -10° C. The predicted STs must be weighted against the extrapolative nature of the model. At present, it would be prudent to use the predictions in a relative sense, that is, to compare or rank-order predicted STs for various combinations of ambient conditions and clothing protection.

  19. The WFIRST Galaxy Survey Exposure Time Calculator

    NASA Technical Reports Server (NTRS)

    Hirata, Christopher M.; Gehrels, Neil; Kneib, Jean-Paul; Kruk, Jeffrey; Rhodes, Jason; Wang, Yun; Zoubian, Julien

    2013-01-01

    This document describes the exposure time calculator for the Wide-Field Infrared Survey Telescope (WFIRST) high-latitude survey. The calculator works in both imaging and spectroscopic modes. In addition to the standard ETC functions (e.g. background and SN determination), the calculator integrates over the galaxy population and forecasts the density and redshift distribution of galaxy shapes usable for weak lensing (in imaging mode) and the detected emission lines (in spectroscopic mode). The source code is made available for public use.

  20. Effects of Perfluorooctanoic Acid on Mouse Mammary Gland Development and Differentiation Resulting from Cross-Foster and Restricted Gestational Exposures

    EPA Science Inventory

    The adverse consequences of developmental exposures to perfluorooctanoic acid (PFOA) have been established, and include impaired development of the offspring mammary gland (MG). However, the relationship between the timing or route of exposure, and the phenotypic consequences in ...

  1. Exposure of acid aerosol for schoolchildren in metropolitan Taipei

    NASA Astrophysics Data System (ADS)

    Mao, I.-Fang; Lin, Chih-Hung; Lin, Chun-Ji; Chen, Yi-Ju; Sung, Fung-Chang; Chen, Mei-Lien

    Metropolitan Taipei, which is located in the subtropical area, is characterized by high population and automobile densities. For convenience, most primary schools are located near major roads. This study explores the exposure of acid aerosols for schoolchildren in areas in Taipei with different traffic densities. Acid aerosols were collected by using a honeycomb denuder filter pack sampling system (HDS). Experimental results indicated that the air pollutants were significantly correlated with traffic densities. The ambient air NO 2, SO 2, HNO 3, NO 3-, SO 42-, and aerosol acidity concentrations were 31.3 ppb, 4.7 ppb, 1.3 ppb, 1.9 μg m -3, 18.5 μg m -3, and 49.5 nmol m -3 in high traffic density areas, and 6.1 ppb, 1.8 ppb, 0.9 ppb, 0.7 μg m -3, 8.8 μg m -3 and 14.7 nmol m -3 in low traffic density areas. The exposure levels of acid aerosols for schoolchildren would be higher than the measurements because the sampling height was 5 m above the ground. The SO 2 levels were low (0.13-8.03 ppb) in the metropolitan Taipei. However, the SO 42- concentrations were relatively high, and might be attributed to natural emissions of sulfur-rich geothermal sources. The seasonal variations of acid aerosol concentrations were also observed. The high levels of acidic particles in spring time may be attributed to the Asian dust storm and low height of the mixture layer. We conclude that automobile contributed not only the primary pollutants but also the secondary acid aerosols through the photochemical reaction. Schoolchildren were exposed to twice the acid aerosol concentrations in high traffic density areas compared to those in low traffic density areas. The incidence of allergic rhinitis of schoolchildren in the high traffic density areas was the highest in spring time. Accompanied by high temperature variation and high levels of air pollution in spring, the health risk of schoolchildren had been observed.

  2. Maternal exposures in the National Birth Defects Prevention Study: time trends of selected exposures

    PubMed Central

    Dawson, April L.; Razzaghi, Hilda; Arth, Annelise; Canfield, Mark A.; Parker, Samantha E.; Reefhuis, Jennita

    2015-01-01

    Background Our objective was to describe time trends in selected pregnancy exposures in the National Birth Defects Prevention Study (NBDPS). Methods We analyzed data from the NBDPS, a multi-site case-control study of major birth defects, for mothers of live-born infants without birth defects (controls), with an expected date of delivery (EDD) from 1998 –2011. Mothers from the 10 participating centers across the United States were interviewed by phone between six weeks and two years after the EDD. We focused on maternal race/ethnicity and five maternal risk factors: obesity, use of folic acid-containing multivitamins, opioid analgesics, selective serotonin reuptake inhibitors (SSRIs), and loratadine because of their prevalence of use and some reports of associations with major birth defects. Prevalence time trends were examined using the Kendall’s τβ test statistic. Results The exposure trend analysis included 11,724 control mothers with EDDs from 1998–2011. We observed a significant increase in obesity prevalence among control mothers, as well as use of SSRIs and loratadine. We also observed an increase in periconceptional use of folic acid-containing multivitamins. Some of the time trends varied by race/ethnicity. No remarkable trend in the overall use of opioid analgesics was observed. The racial/ethnic distribution of mothers changed slightly during the study period. Conclusions Long-term, population-based case-control studies continue to be an effective way to assess exposure-birth defects associations and provide guidance to health care providers. However, investigators examining rare outcomes covering many years of data collection need to be cognizant of time trends in exposures. PMID:25884728

  3. Perfluorooctanoic Acid Exposure Suppresses T-independent Antibody Responses

    EPA Science Inventory

    Exposure to  3.75mg/kg of perfluoroocatnoic acid (PFOA) for 15d suppresses T-dependent antibody responses (TDAR), suggesting that T helper cells and/or B cells/plasma cells may be impacted. This study evaluated effects of PFOA exposure on the T cell-independent antibody response...

  4. Human health effects of exposure to airborne acid.

    PubMed

    Folinsbee, L J

    1989-02-01

    This paper summarizes and critiques a series of reports on the health effects of acid aerosol exposure, presented at the Symposium on the Health Effects of Acid Aerosols and compares these data to selected previous studies. The role of the two major defenses against acid aerosols, the conversion of acid to the ammonium salts by respiratory ammonia and buffering of acid by airway surface liquid are discussed in relation to airway acid burdens expected from typical inhalation exposures. The roles of particle size and hygroscopicity on airway deposition of aerosol are also included. The major health effects studied were the effects of acid aerosol on mucociliary clearance in healthy individuals and changes in lung function in asthmatics, an important sensitive subpopulation. The broad range of response in asthmatics suggests the need for further study.

  5. Zebrafish retinal defects induced by ethanol exposure are rescued by retinoic acid and folic acid supplement.

    PubMed

    Muralidharan, Pooja; Sarmah, Swapnalee; Marrs, James A

    2015-03-01

    Fetal Alcohol Spectrum Disorder (FASD) is caused by prenatal alcohol exposure, producing craniofacial, sensory, motor, and cognitive defects. FASD is highly prevalent in low socioeconomic populations, which are frequently accompanied by malnutrition. FASD-associated ocular pathologies include microphthalmia, optic nerve hypoplasia, and cataracts. The present study characterizes specific retinal tissue defects, identifies ethanol-sensitive stages during retinal development, and dissects the effect of nutrient supplements, such as retinoic acid (RA) and folic acid (FA) on ethanol-induced retinal defects. Exposure to pathophysiological concentrations of ethanol (during midblastula transition through somitogenesis; 2-24 h post fertilization [hpf]) altered critical transcription factor expression involved in retinal cell differentiation, and produced severe retinal ganglion cell, photoreceptor, and Müller glial differentiation defects. Ethanol exposure did not alter retinal cell differentiation induction, but increased retinal cell death and proliferation. RA and FA nutrient co-supplementation rescued retinal photoreceptor and ganglion cell differentiation defects. Ethanol exposure during retinal morphogenesis stages (16-24 hpf) produced retinal defects like those seen with ethanol exposure between 2 and 24 hpf. Significantly, during an ethanol-sensitive time window (16-24 hpf), RA co-supplementation moderately rescued these defects, whereas FA co-supplementation showed significant rescue of optic nerve and photoreceptor differentiation defects. Interestingly, RA, but not FA, supplementation after ethanol exposure could reverse ethanol-induced optic nerve and photoreceptor differentiation defects. Our results indicate that various ethanol-sensitive events underlie FASD-associated retinal defects. Nutrient supplements like retinoids and folate were effective in alleviating ethanol-induced retinal defects.

  6. Zebrafish retinal defects induced by ethanol exposure are rescued by retinoic acid and folic acid supplement

    PubMed Central

    Muralidharan, Pooja; Sarmah, Swapnalee; Marrs, James A.

    2014-01-01

    Fetal Alcohol Spectrum Disorder (FASD) is caused by prenatal alcohol exposure, producing craniofacial, sensory, motor, and cognitive defects. FASD is highly prevalent in low socioeconomic populations, which are frequently accompanied by malnutrition. FASD-associated ocular pathologies include microphthalmia, optic nerve hypoplasia, and cataracts. The present study characterizes specific retinal tissue defects, identifies ethanol-sensitive stages during retinal development, and dissects the effect of nutrient supplements, such as retinoic acid (RA) and folic acid (FA) on ethanol-induced retinal defects. Exposure to pathophysiological concentrations of ethanol (during midblastula transition through somitogenesis; 2–24 hours post fertilization [hpf]) altered critical transcription factor expression involved in retinal cell differentiation, and produced severe retinal ganglion cell, photoreceptor, and Müller glial differentiation defects. Ethanol exposure did not alter retinal cell differentiation induction, but increased retinal cell death and proliferation. RA and FA nutrient co-supplementation rescued retinal photoreceptor and ganglion cell differentiation defects. Ethanol exposure during retinal morphogenesis stages (16–24 hpf) produced retinal defects like those seen with ethanol exposure between 2–24 hpf. Significantly, during an ethanol-sensitive time window (16–24 hpf), RA co-supplementation moderately rescued these defects, whereas FA co-supplementation showed significant rescue of optic nerve and photoreceptor differentiation defects. Interestingly, RA, but not FA, supplementation after ethanol exposure could reverse ethanol-induced optic nerve and photoreceptor differentiation defects. Our results indicate that various ethanol-sensitive events underlie FASD-associated retinal defects. Nutrient supplements like retinoids and folate were effective in alleviating ethanol-induced retinal defects. PMID:25541501

  7. Airborne acidity: estimates of exposure and human health effects.

    PubMed Central

    Lippmann, M

    1985-01-01

    Human health effects have resulted from the inhalation of ambient acidic aerosols, and there is suggestive evidence that current North American levels of exposure are producing excesses in respiratory morbidity. Annual mean mortality rates have been correlated with ambient aerosol concentration indices, with SO4(2-), FP, IP, and TSP having a descending order as predictive coefficients. These pollutant indices also contain H+ in descending mass ratios, and may all be surrogates for H+ as an active agent. Controlled exposure studies in humans and animals provide evidence that acidic aerosols produce greater changes in respiratory mechanical function and rates of particle clearance than other constituents of ambient particulate matter. The strong acid content of the ambient aerosol has not been measured in any of the population based pollutant effects studies in which it is a likely causal factor. The absence of direct measurement data on acidic aerosol in these studies, and their reliance on surrogate indices such as SO2 and SO4(2-), precludes firm conclusions about exposure-response relationships. High priority areas for further investigation include systematic investigation of the spatial and temporal distribution of population exposures; extension and refinement of population response studies in relation to acid aerosol exposures; responses of normal healthy and asthmatic human volunteers to mixtures of acidic aerosols and oxidant vapors under controlled conditions of exposure and exercise intensity; and progression of changes in lung epithelia during repetitive daily exposures of experimental animals to acidic aerosols, oxidants, and their mixtures, with concurrent measurements of particle clearance and respiratory function. PMID:4076095

  8. Real time chemical exposure and risk monitor

    DOEpatents

    Thrall, Karla D.; Kenny, Donald V.; Endres, George W. R.; Sisk, Daniel R.

    1997-01-01

    The apparatus of the present invention is a combination of a breath interface and an external exposure dosimeter interface to a chemical analysis device, all controlled by an electronic processor for quantitatively analyzing chemical analysis data from both the breath interface and the external exposure dosimeter for determining internal tissue dose. The method of the present invention is a combination of steps of measuring an external dose, measuring breath content, then analyzing the external dose and breath content and determining internal tissue dose.

  9. Effects of Graduated Exposure with Feedback of Exposure Times on Snake Phobias

    ERIC Educational Resources Information Center

    Becker, Horst G.; Costello, C. G.

    1975-01-01

    The subject-controlled graduated exposure of a snake with feedback of exposure times resulted in significantly less avoidance behaviors for snake-phobic subjects than for control snake-phobic subjects who did not receive therapy. (Author)

  10. Effects of nitrous acid exposure on human mucous membranes.

    PubMed

    Rasmussen, T R; Brauer, M; Kjaergaard, S

    1995-05-01

    Nitrous acid (HONO) is formed both indirectly from the reaction of nitrogen dioxide (NO2) with water on indoor surfaces, and directly during combustion. This gaseous pollutant may be a previously unrecognized causal factor in assessments of nitrogen oxide exposure effects. The present study is the first attempt to evaluate exposure effects of HONO on the human airways and the mucous membranes of the eyes and nose. Fifteen healthy adult nonsmokers were exposed for 3.5 h in a double-blind, balanced protocol to clean air, 77, and 395 ppb HONO. Each exposure was preceded by a 1-h baseline measurement period, and exposures were separated by 1 wk. There was a 10-min exercise period during exposure. Effects measurements included assessment of bronchial reactivity, measurement of specific airway conductance, spirometry, acoustic rhinometry, nasal lavage, tear-fluid cytology, a CO2 eye-provocation test, evaluation of eye redness, and subjective sensations. Effects of HONO exposure on the eyes were found as exposure-related changes in tear-fluid cytology. In particular, the number of squamous cells increased by 20, 67, and 80% following exposure to clean air, 77, and 395 ppb HONO, respectively (p = 0.004). Possible indications of exposure effects on sensitivity to CO2 eye provocation and on specific airway conductance were also measured. For specific airway conductance there was an approximate 10% decrease in conductance following exercise in association with HONO exposure, compared with a 2% decrease with clean air (p = 0.038).

  11. Real time chemical exposure and risk monitor

    DOEpatents

    Thrall, K.D.; Kenny, D.V.; Endres, G.W.R.; Sisk, D.R.

    1997-07-08

    The apparatus of the present invention is a combination of a breath interface and an external exposure dosimeter interface to a chemical analysis device, all controlled by an electronic processor for quantitatively analyzing chemical analysis data from both the breath interface and the external exposure dosimeter for determining internal tissue dose. The method of the present invention is a combination of steps of measuring an external dose, measuring breath content, then analyzing the external dose and breath content and determining internal tissue dose. 7 figs.

  12. Sulfuric acid aerosol exposure in humans assessed by bronchoalveolar lavage

    SciTech Connect

    Frampton, M.W.; Voter, K.Z.; Morrow, P.E.; Roberts, N.J. Jr.; Culp, D.J.; Cox, C.; Utell, M.J. )

    1992-09-01

    Epidemiologic and experimental evidence suggests that exposure to acidic aerosols may affect human health. Brief exposures to acidic aerosols alter mucociliary clearance and increase airway responsiveness, but effects on host defense mechanisms at the alveolar level have not been studied in humans. Twelve healthy, nonsmoking volunteers between 20 and 39 yr of age were exposed for 2 h to aerosols of approximately 1,000 micrograms/m3 sulfuric acid (H2SO4) or sodium chloride (NaCl (control)), with intermittent exercise, in a randomized, double-blind fashion. Each subject received both exposures, separated by at least 2 wk. Bronchoalveolar lavage (BAL) was performed 18 h after exposure in order to detect evidence of an inflammatory response, changes in alveolar cell subpopulations, or changes in alveolar macrophage (AM) function, which is important in host defense. When compared with NaCl, exposure to H2SO4 did not increase polymorphonuclear leukocytes in BAL fluid. The percentage of T lymphocytes decreased in association with H2SO4 exposure, but the difference was not statistically significant (14.9% after NaCl, 11.5% after H2SO4; p = 0.14). Antibody-mediated cytotoxicity of AM increased in association with H2SO4 exposure (percent lysis 19.1 after NaCl, 23.6 after H2SO4; p = 0.16). No significant change was seen in release of superoxide anion or inactivation of influenza virus in vitro. Brief exposures to H2SO4 aerosol at 1,000 micrograms/m3 do not cause an influx of inflammatory cells into the alveolar space, and no evidence was found for alteration in antimicrobial defense 18 h after exposure.

  13. Time-activity relationships to VOC personal exposure factors

    NASA Astrophysics Data System (ADS)

    Edwards, Rufus D.; Schweizer, Christian; Llacqua, Vito; Lai, Hak Kan; Jantunen, Matti; Bayer-Oglesby, Lucy; Künzli, Nino

    Social and demographic factors have been found to play a significant role in differences between time-activity patterns of population subgroups. Since time-activity patterns largely influence personal exposure to compounds as individuals move across microenvironments, exposure subgroups within the population may be defined by factors that influence daily activity patterns. Socio-demographic and environmental factors that define time-activity subgroups also define quantifiable differences in VOC personal exposures to different sources and individual compounds in the Expolis study. Significant differences in exposures to traffic-related compounds ethylbenzene, m- and p-xylene and o-xylene were observed in relation to gender, number of children and living alone. Categorization of exposures further indicated time exposed to traffic at work and time in a car as important determinants. Increased exposures to decane, nonane and undecane were observed for males, housewives and self-employed. Categorization of exposures indicated exposure subgroups related to workshop use and living downtown. Higher exposures to 3-carene and α-pinene commonly found in household cleaning products and fragrances were associated with more children, while exposures to traffic compounds ethylbenzene, m- and p-xylene and o-xylene were reduced with more children. Considerable unexplained variation remained in categorization of exposures associated with home product use and fragrances, due to individual behavior and product choice. More targeted data collection methods in VOC exposure studies for these sources should be used. Living alone was associated with decreased exposures to 2-methyl-1-propanol and 1-butanol, and traffic-related compounds. Identification of these subgroups may help to reduce the large amount of unexplained variation in VOC exposure studies. Further they may help in assessing impacts of urban planning that result in changes in behavior of individuals, resulting in shifts in

  14. Exposure time optimization for highly dynamic star trackers.

    PubMed

    Wei, Xinguo; Tan, Wei; Li, Jian; Zhang, Guangjun

    2014-03-11

    Under highly dynamic conditions, the star-spots on the image sensor of a star tracker move across many pixels during the exposure time, which will reduce star detection sensitivity and increase star location errors. However, this kind of effect can be compensated well by setting an appropriate exposure time. This paper focuses on how exposure time affects the star tracker under highly dynamic conditions and how to determine the most appropriate exposure time for this case. Firstly, the effect of exposure time on star detection sensitivity is analyzed by establishing the dynamic star-spot imaging model. Then the star location error is deduced based on the error analysis of the sub-pixel centroiding algorithm. Combining these analyses, the effect of exposure time on attitude accuracy is finally determined. Some simulations are carried out to validate these effects, and the results show that there are different optimal exposure times for different angular velocities of a star tracker with a given configuration. In addition, the results of night sky experiments using a real star tracker agree with the simulation results. The summarized regularities in this paper should prove helpful in the system design and dynamic performance evaluation of the highly dynamic star trackers.

  15. Identifiability of PBPK models with applications to dimethylarsinic acid exposure.

    PubMed

    Garcia, Ramon I; Ibrahim, Joseph G; Wambaugh, John F; Kenyon, Elaina M; Setzer, R Woodrow

    2015-12-01

    Any statistical model should be identifiable in order for estimates and tests using it to be meaningful. We consider statistical analysis of physiologically-based pharmacokinetic (PBPK) models in which parameters cannot be estimated precisely from available data, and discuss different types of identifiability that occur in PBPK models and give reasons why they occur. We particularly focus on how the mathematical structure of a PBPK model and lack of appropriate data can lead to statistical models in which it is impossible to estimate at least some parameters precisely. Methods are reviewed which can determine whether a purely linear PBPK model is globally identifiable. We propose a theorem which determines when identifiability at a set of finite and specific values of the mathematical PBPK model (global discete identifiability) implies identifiability of the statistical model. However, we are unable to establish conditions that imply global discrete identifiability, and conclude that the only safe approach to analysis of PBPK models involves Bayesian analysis with truncated priors. Finally, computational issues regarding posterior simulations of PBPK models are discussed. The methodology is very general and can be applied to numerous PBPK models which can be expressed as linear time-invariant systems. A real data set of a PBPK model for exposure to dimethyl arsinic acid (DMA(V)) is presented to illustrate the proposed methodology. PMID:26194069

  16. Lead exposure among lead-acid battery workers in Jamaica.

    PubMed

    Matte, T D; Figueroa, J P; Burr, G; Flesch, J P; Keenlyside, R A; Baker, E L

    1989-01-01

    To assess lead exposure in the Jamaican lead-acid battery industry, we surveyed three battery manufacturers (including 46 production workers) and 10 battery repair shops (including 23 battery repair workers). Engineering controls and respiratory protection were judged to be inadequate at battery manufacturers and battery repair shops. At manufacturers, 38 of 42 air samples for lead exceeded a work-shift time-weighted average concentration of 0.050 mg/m3 (range 0.030-5.3 mg/m3), and nine samples exceeded 0.50 mg/m3. Only one of seven air samples at repair shops exceeded 0.050 mg/m3 (range 0.003-0.066 mg/m3). Repair shop workers, however, had higher blood lead levels than manufacturing workers (65% vs. 28% with blood lead levels above 60 micrograms/dl, respectively). Manufacturing workers had a higher prevalence of safe hygienic practices and a recent interval of minimal production had occurred at one of the battery manufacturers. Workers with blood lead levels above 60 micrograms/dl tended to have higher prevalences of most symptoms of lead toxicity than did workers with lower blood lead levels, but this finding was not consistent or statistically significant. The relationship between zinc protoporphyrin concentrations and increasing blood lead concentrations was consistent with that described among workers in developed countries. The high risk of lead toxicity among Jamaican battery workers is consistent with studies of battery workers in other developing countries. PMID:2773946

  17. Lead exposure among lead-acid battery workers in Jamaica.

    PubMed

    Matte, T D; Figueroa, J P; Burr, G; Flesch, J P; Keenlyside, R A; Baker, E L

    1989-01-01

    To assess lead exposure in the Jamaican lead-acid battery industry, we surveyed three battery manufacturers (including 46 production workers) and 10 battery repair shops (including 23 battery repair workers). Engineering controls and respiratory protection were judged to be inadequate at battery manufacturers and battery repair shops. At manufacturers, 38 of 42 air samples for lead exceeded a work-shift time-weighted average concentration of 0.050 mg/m3 (range 0.030-5.3 mg/m3), and nine samples exceeded 0.50 mg/m3. Only one of seven air samples at repair shops exceeded 0.050 mg/m3 (range 0.003-0.066 mg/m3). Repair shop workers, however, had higher blood lead levels than manufacturing workers (65% vs. 28% with blood lead levels above 60 micrograms/dl, respectively). Manufacturing workers had a higher prevalence of safe hygienic practices and a recent interval of minimal production had occurred at one of the battery manufacturers. Workers with blood lead levels above 60 micrograms/dl tended to have higher prevalences of most symptoms of lead toxicity than did workers with lower blood lead levels, but this finding was not consistent or statistically significant. The relationship between zinc protoporphyrin concentrations and increasing blood lead concentrations was consistent with that described among workers in developed countries. The high risk of lead toxicity among Jamaican battery workers is consistent with studies of battery workers in other developing countries.

  18. [Lead exposure in the ceramic tile industry: time trends and current exposure levels].

    PubMed

    Candela, S; Ferri, F; Olmi, M

    1998-01-01

    There is a high density of industries for the production of ceramic tiles in the District of Scandiano (province of Reggio Emilia, Emilia Romagna region). In this area, since the beginning of 1970s, the time trend of Pb exposure in ceramic tile plants has been evaluated by means of biological monitoring (BM) data collected at the Service of Prevention and Safety in the Work Environment and its associated Toxicology Laboratory. From these data, a clear decreasing time trend of exposure levels is documented, the reduction being more evident during the seventies and in 1985-88. During the seventies BM was introduced systematically in all ceramic tile plants with the determination of delta-aminolevulinic acid in urine (ALA-U). As a consequence of the BM programme, hygienic measures for the abatement of pollution inside the plants were implemented, and a reduction, from 20.6% to 2%, of ALA-U values exceeding 10 mg/l, was observed. In 1985, the determination of lead in blood (PbB) replaced that of ALA-U in the BM programmes and highlighted the persistence of high level of exposure to Pb, which could not be outlined by means of ALA-U because of its lower sensitivity. PbB levels were 36.1 micrograms/100 ml and 25.7 micrograms/100 ml in male and female workers, respectively. These results required the implementation, within the plants, of additional hygienic measures and a significant reduction of PbB was obtained in the following three years. In 1988 PbB levels were 26.0 +/- 10.7 and 21.6 +/- 10.3 micrograms/100 ml in male and female workers, respectively. In 1993-95 Pb levels were obtained from 1328 male and 771 female workers of 56 plants, accounting for about 40% of the total number of workers in the ceramic industry, in the zones of Sassuolo and Scandiano. Exposure levels are not different from those observed in the preceding years, with PbB levels of 25.3 +/- 11.1 and 19.1 +/- 9.2 micrograms/100 ml in male and female workers, respectively.

  19. Characterizing Determinants of Risk: Concentration, Duration, and Timing of Exposure

    EPA Science Inventory

    An ongoing challenge in human health risk assessment is to determine the best approach for characterizing the risk from real-world exposures. Three major determinants characterize exposure: concentration (how much), duration (the frequency and how long), and critical timing (whe...

  20. Acid exposure induces multiplication of Salmonella enterica serovar Typhi.

    PubMed

    Ahirwar, Suneel Kumar; Pratap, Chandra Bhan; Patel, Saurabh Kumar; Shukla, Vijay K; Singh, Indarjeet Gambhir; Mishra, Om Prakash; Kumar, Kailash; Singh, Tej Bali; Nath, Gopal

    2014-12-01

    Salmonella enterica serovar Typhi faces several environmental stresses while going through the stomach (acidic pH) to the small intestine (basic pH) and intracellularly in macrophages (acidic pH) in humans. The acidic pH followed by alkaline pH in the small intestine might be responsible for expression of certain stress-induced genes, resulting in not only better survival but also induction of multiplication and invasion of the bacterium in the small intestine. Based on this hypothesis, we developed a process wherein we exposed the blood, urine, and stool specimens from 90 acute typhoid fever patients and 36 chronic typhoid carriers to acidic pH to see the effect on isolation rate of S. Typhi. About 5 g of freshly passed unpreserved stool, a centrifuged deposit of 15 ml of urine, and 5 ml of blood clot were subjected to 5 ml of Luria-Bertani (LB) broth (pH 3.5) for 20 min, followed by enrichment in bile broth-selenite F broth. When the combined isolation from all 3 specimens, i.e., blood, urine, and stool, after acid exposure was considered, a total of 77.7% of the acute typhoid patients were observed to be positive for the isolation of the S. Typhi serotype, compared to 8.8% by the conventional method. Similarly, 42% (15/36) of chronic carriers yielded positive for S. Typhi growth after acid exposure, compared to 5.5% (2/36) by the conventional method. It therefore can be concluded that acid shock triggers the multiplication of the bacteria, resulting in better isolation rates from blood clot, stool, and urine specimens.

  1. Time-distributed effect of exposure and infectious outbreaks

    PubMed Central

    Naumova, Elena N.; MacNeill, Ian B.

    2009-01-01

    SUMMARY Extreme weather affects the timing and intensity of infectious outbreaks, the resurgence and redistribution of infections, and it causes disturbances in human-environment interactions. Environmental stressors with high thermoregulatory demands require susceptible populations to undergo physiological adaptive processes potentially compromising immune function and increasing susceptibility to infection. In assessing associations between environmental exposures and infectious diseases, failure to account for a latent period between time of exposure and time of disease manifestation may lead to severe underestimation of the effects. In a population, health effects of an episode of exposure are distributed over a range of time lags. To consider such time-distributed lags is a challenging task given that the length of a latent period varies from hours to months and depends on the type of pathogen, individual susceptibility to the pathogen, dose of exposure, route of transmission, and many other factors. The two main objectives of this communication are to introduce an approach to modeling time-distributed effect of exposures to infection cases and to demonstrate this approach in an analysis of the association between high ambient temperature and daily incidence of enterically transmitted infections. The study is supplemented with extensive simulations to examine model sensitivity to response magnitude, exposure frequency, and extent of latent period. PMID:19881890

  2. EFFECTS OF PERFLUOROOCTANOIC ACID EXPOSURE DURING PREGNANCY IN THE MOUSE

    EPA Science Inventory

    Perfluorooctanoic acid (PFOA), a member of the perfluoroalkyl acids that have wide commercial applications, has recently been detected in humans and wildlife. The current study characterizes the developmental toxicity of PFOA in the mouse. Timed pregnant CD-1 mice were given 1,...

  3. Effects of carbaryl on green frog (Rana clamitans) tadpoles: Timing of exposure versus multiple exposures

    USGS Publications Warehouse

    Boone, M.D.; Bridges, C.M.

    2003-01-01

    The majority of studies on pesticide impacts have evaluated the effects of single exposures. However, multiple exposures to a pesticide may be more prevalent. The objective of our study was to determine how multiple exposures versus single exposure at different times during development affected survival to metamorphosis, tadpole survival, tadpole mass, and tadpole developmental stage of green frog (Rana clamitans) tadpoles reared at low and high density in outdoor cattle tank ponds. Tadpoles were exposed to carbaryl zero, one, two, or three times at 14-d intervals. We applied single doses of carbaryl at one of three times, specifically during early, mid, or late development. Overall, we found that multiple exposures had a greater impact than single exposures during development. More individuals reached metamorphosis in ponds exposed to multiple doses of carbaryl compared with controls, indicating that the presence of carbaryl stimulated metamorphosis. The presence of carbaryl in the aquatic environment also resulted in more developed tadpoles compared with controls. Tadpoles in control ponds did not reach metamorphosis and were less developed than individuals exposed to carbaryl; this effect indicates that, under ideal conditions, green frogs could overwinter in ponds so that greater size could be attained before metamorphosis in the following spring or summer. Our study demonstrated the importance of including realistic application procedures when evaluating the effects of a pesticide and that multiple exposures to a short-lived pesticide are more likely to affect an amphibian population.

  4. Biomarker-Based Calibration of Retrospective Exposure Predictions of Perfluorooctanoic Acid

    PubMed Central

    2015-01-01

    Estimated historical exposures and serum concentrations of perfluorooctanoic acid (PFOA) have been extensively used in epidemiologic studies that examined associations between PFOA exposures and adverse health outcomes among residents in highly exposed areas in the Mid-Ohio Valley. Using measured serum PFOA levels in 2005–2006, we applied two calibration methods to these retrospective exposure predictions: (1) multiplicative calibration and (2) Bayesian pharmacokinetic calibration with larger adjustments to more recent exposure estimates and smaller adjustments to exposure estimates for years farther in the past. We conducted simulation studies of various hypothetical exposure scenarios and compared hypothetical true historical intake rates with estimates based on mis-specified baseline exposure and pharmacokinetic models to find the method with the least bias. The Bayesian method outperformed the multiplicative method if a change to bottled water consumption was not reported or if the half-life of PFOA was mis-specified. On the other hand, the multiplicative method outperformed the Bayesian method if actual tap water consumption rates were systematically overestimated. If tap water consumption rates gradually decreased over time because of substitution with bottled water or other liquids, neither method clearly outperformed another. Calibration of retrospective exposure estimates using recently collected biomarkers may help reduce uncertainties in environmental epidemiologic studies. PMID:24730513

  5. Exposure assessment of boron in Bandırma boric acid production plant.

    PubMed

    Duydu, Yalçin; Başaran, Nurşen; Bolt, Hermann M

    2012-06-01

    Boric acid and sodium borates have been considered as being "toxic to reproduction and development", following results of animal studies with high doses. Experimentally, a NOAEL of 17.5mg B/kg-bw/day (corresponds to ∼2020 ng boron/g blood) has been identified for the (male) reproductive effects of boron in a multigenerational study of rats, and a NOAEL for the developmental effects in rats was identified at 9.6 mg B/kg-bw/day (corresponds to 1270 ng boron/g blood). These values are being taken as the basis of current EU safety assessments. The present study was conducted to assess the boron exposure under extreme exposure conditions in a boric acid production plant located in Bandırma, Turkey. The mean blood boron concentrations of low and high exposure groups were 72.94 ± 15.43 (48.46-99.91) and 223.89 ± 60.49 (152.82-454.02)ng/g respectively. The mean blood boron concentration of the high exposure group is still ≈ 6 times lower than the highest no effect level of boron in blood with regard to the developmental effects in rats and ≈ 9 times lower than the highest no effect level of boron in blood with regard to the reprotoxic effects in male rats. In this context, boric acid and sodium borates should not be considered as toxic to reproduction for humans in daily life.

  6. Early life perfluorooctanesulphonic acid (PFOS) exposure impairs zebrafish organogenesis

    PubMed Central

    Chen, Jiangfei; Tanguay, Robert L.; Tal, Tamara L.; Bai, Chenglian; Tilton, Susan C.; Jin, Daqing; Yang, Dongren; Huang, Changjiang; Dong, Qiaoxiang

    2014-01-01

    As a persistent organic contaminant, perfluorooctanesulphonic acid (PFOS) has been widely detected in the environment, wildlife, and humans. The present study revealed that zebrafish embryos exposed to 16 µM PFOS during a sensitive window of 48–96 hour post-fertilization (hpf) disrupted larval morphology at 120 hpf. Malformed zebrafish larvae were characterized by uninflated swim bladder, less developed gut, and curved spine. Histological and ultrastructural examination of PFOS-exposed larvae showed structural alterations in swim bladder and gut. Whole genome microarray was used to identify the early transcripts dysregulated following exposure to 16 µM PFOS at 96 hpf. In total, 1,278 transcripts were significantly misexpressed (p < 0.05) and 211 genes were changed at least two-fold upon PFOS exposure in comparison to the vehicle exposed control group. A PFOS-induced network of perturbed transcripts relating to swim bladder and gut development revealed that misexpression of genes were involved in organogenesis. Taken together, early life stage exposure to PFOS perturbs various molecular pathways potentially resulting in observed defects in swim bladder and gut development. PMID:24667235

  7. Recovery of duckweed from time-varying exposure to atrazine.

    PubMed

    Brain, Richard A; Hosmer, Alan J; Desjardins, Debbie; Kendall, Timothy Z; Krueger, Henry O; Wall, Steven B

    2012-05-01

    The purpose of the present study was to evaluate the recovery of duckweed (Lemna gibba L. G3) after being removed from multiple duration exposures to the herbicide atrazine. Consequently, L. gibba were exposed under various scenarios to atrazine at nominal concentrations ranging from 5 to 160 µg/L and durations of 1, 3, 5, 7, 9, and 14 d under static-renewal test conditions. Exposures were followed by a recovery phase in untreated media for either 7 or 14 d. The 3-, 5-, 7-, 9-, and 14-d median effective concentration (EC50) values were >137, >137, 124, >77, and >75 µg/L, respectively, based on mean growth rate. No clear effect trends were apparent between exposure duration and the magnitude of effective concentrations (EC50s or EC10s). No phytocidal effects of chlorosis or necrosis were identified for any treatment scenario. Nearly all L. gibba plants transferred from treatment groups of different exposure scenarios to media without atrazine during the recovery phase had growth rates that demonstrated immediate recovery, indicating effects were phytostatic in nature and reversible. Only the 1- and 5-d exposure scenarios had growth rates indicating marginally prolonged recovery at the higher concentrations (160 µg/L; additionally, at 40 µg/L for the 5-d exposure). Time to recovery, therefore, was found to be largely independent of exposure duration except at the highest concentrations assessed. Based on growth rate by interval, all treatments demonstrated recovery by the final assessment interval (days 5-7), indicating complete recovery in all exposure scenarios by 7 d, consistent with the mode of action of atrazine. PMID:22431202

  8. Recovery of duckweed from time-varying exposure to atrazine.

    PubMed

    Brain, Richard A; Hosmer, Alan J; Desjardins, Debbie; Kendall, Timothy Z; Krueger, Henry O; Wall, Steven B

    2012-05-01

    The purpose of the present study was to evaluate the recovery of duckweed (Lemna gibba L. G3) after being removed from multiple duration exposures to the herbicide atrazine. Consequently, L. gibba were exposed under various scenarios to atrazine at nominal concentrations ranging from 5 to 160 µg/L and durations of 1, 3, 5, 7, 9, and 14 d under static-renewal test conditions. Exposures were followed by a recovery phase in untreated media for either 7 or 14 d. The 3-, 5-, 7-, 9-, and 14-d median effective concentration (EC50) values were >137, >137, 124, >77, and >75 µg/L, respectively, based on mean growth rate. No clear effect trends were apparent between exposure duration and the magnitude of effective concentrations (EC50s or EC10s). No phytocidal effects of chlorosis or necrosis were identified for any treatment scenario. Nearly all L. gibba plants transferred from treatment groups of different exposure scenarios to media without atrazine during the recovery phase had growth rates that demonstrated immediate recovery, indicating effects were phytostatic in nature and reversible. Only the 1- and 5-d exposure scenarios had growth rates indicating marginally prolonged recovery at the higher concentrations (160 µg/L; additionally, at 40 µg/L for the 5-d exposure). Time to recovery, therefore, was found to be largely independent of exposure duration except at the highest concentrations assessed. Based on growth rate by interval, all treatments demonstrated recovery by the final assessment interval (days 5-7), indicating complete recovery in all exposure scenarios by 7 d, consistent with the mode of action of atrazine.

  9. Use of time to pregnancy to study environmental exposures

    SciTech Connect

    Baird, D.D.; Wilcox, A.J.; Weinberg, C.R.

    1986-09-01

    There is need in reproductive epidemiology for sensitive and convenient screening tools that can be used to study environmental and occupational exposures. The measurement of fecundability (the probability of pregnancy in each cycle) by ascertaining how long it takes couples to conceive, may be useful for this purpose. Theoretically, exposures that interfere with any of the biologic processes involved in achieving pregnancy could lower fecundability among exposed men or women. To evaluate problems with collecting data on time to pregnancy, telephone interviews were conducted with nearly 700 pregnant women who reported having planned their pregnancies. Power curves were developed based on the distribution of time to pregnancy in the interviewed population. These curves indicate that relatively small sample sizes are sufficient for investigating an exposure. For example, the authors estimate that to detect a given 50% drop in mean fecundability with 80% power would require data from 55 exposed and 55 unexposed women who are pregnant. Disadvantages of using time to pregnancy as a reproductive endpoint include susceptibility to selection bias and need for data on several potential confounding variables. The next step in evaluating time to pregnancy as a reproductive endpoint is to apply it in studies of environmental or occupational exposures.

  10. Developmental timing of perchlorate exposure alters threespine stickleback dermal bone

    PubMed Central

    Furin, Christoff G.; von Hippel, Frank A.; Postlethwait, John; Buck, C. Loren; Cresko, William A.; O’Hara, Todd M.

    2015-01-01

    Adequate levels of thyroid hormone are critical during development and metamorphosis, and for maintaining metabolic homeostasis. Perchlorate, a common contaminant of water sources, inhibits thyroid function in vertebrates. We utilized threespine stickleback (Gasterosteus aculeatus) to determine if timing of perchlorate exposure during development impacts adult dermal skeletal phenotypes. Fish were exposed to water contaminated with perchlorate (30 mg/L or 100 mg/L) beginning at 0, 3, 7, 14, 21, 42, 154 or 305 days post fertilization until sexual maturity at one year of age. A reciprocal treatment moved stickleback from contaminated to clean water on the same schedule providing for different stages of initial exposure and different treatment durations. Perchlorate exposure caused concentration-dependent significant differences in growth for some bony traits. Continuous exposure initiated within the first 21 days post fertilization had the greatest effects on skeletal traits. Exposure to perchlorate at this early stage can result in small traits or abnormal skeletal morphology of adult fish which could affect predator avoidance and survival. PMID:25753171

  11. Acute exposure to acid fog. Effects on mucociliary clearance

    SciTech Connect

    Laube, B.L.; Bowes, S.M. III; Links, J.M.; Thomas, K.K.; Frank, R. )

    1993-05-01

    Submicrometric sulfuric acid (H2SO4) aerosol can affect mucociliary clearance without eliciting irritative symptoms or changes in pulmonary function. The effect of larger fog droplets containing H2SO4 on mucociliary clearance is unknown. We quantified mucociliary clearance from the trachea (n = 4) and small airways (n = 7) of young healthy male adults after an acute exposure to H2SO4 fog (MMAD = 10.3 microns; pH = 2.0; liquid water content = 481 +/- 65 mg/m3; osmolarity = 30 mOsm). Acid fog (AF) or saline fog (SF) (10.9 microns; 492 +/- 116 mg/m3; 30 mOsm) was administered for 40 min of unencumbered breathing (no mouth-piece) at rest and for 20 min of exercise sufficient to produce oronasal breathing. Fog exposures were followed by a methacholine (MCh) challenge (a measure of airway reactivity) or inhalation of technetium-99M radioaerosol (MMAD = 3.4 microns) on 2 study days each. Changes in symptoms and forced ventilatory function were also assessed. Clearance was quantified from computer-assisted analyses of gamma camera images of the lower respiratory tract in terms of %removal/min of the radiolabel from the trachea 25 min after inhalation and from the outer zone of the right lung after 1.9 to 3 h. Symptoms, forced ventilatory function, and MCh response were unaffected by either fog. Tracheal clearance was more rapid in four of four subjects after AF (0.83 +/- 1.58% removal/min) compared with that after SF (-0.54 +/- 0.85% removal/min). Outer zone clearance was more rapid in six of seven subjects after AF (0.22 +/- 0.15% removal/min) compared with that after SF (0.01 +/- 0.09% removal/min).

  12. Prenatal arachidonic acid exposure and selected immune-related variables in childhood.

    PubMed

    Dirix, Chantal E H; Hogervorst, Janneke G F; Rump, Patrick; Hendriks, Johannes J E; Bruins, Maaike; Hornstra, Gerard

    2009-08-01

    Arachidonic acid (AA) is considered essential in fetal development and some of its metabolites are thought to be important mediators of the immune responses. Therefore, we studied whether prenatal exposure to AA is associated with some immune-related clinical conditions and plasma markers in childhood. In 280 children aged 7 years, atopy, lung function and plasma inflammation markers were measured and their relationships with early AA exposure were studied by linear and logistic regression analyses. AA exposure was deduced from AA concentrations in plasma phospholipids of the mothers collected at several time points during pregnancy and at delivery, and in umbilical cord plasma and arterial and venous wall phospholipids. In unadjusted regression analyses, significant positive associations were observed between maternal AA concentrations at 16 and 32 weeks of pregnancy (proxies for fetal AA exposure) and peak expiratory flow decline after maximal physical exercise and plasma fibrinogen concentrations of their children, respectively. However, after correction for relevant covariables, only trends remained. A significant negative relationship was observed between AA concentrations in cord plasma (reflecting prenatal AA exposure) and the average daily amplitude of peak expiratory flow at rest, which lost significance after appropriate adjustment. Because of these few, weak and inconsistent relationships, a major impact of early-life exposure to AA on atopy, lung function and selected plasma inflammation markers of children at 7 years of age seems unlikely.

  13. Prenatal arachidonic acid exposure and selected immune-related variables in childhood.

    PubMed

    Dirix, Chantal E H; Hogervorst, Janneke G F; Rump, Patrick; Hendriks, Johannes J E; Bruins, Maaike; Hornstra, Gerard

    2009-08-01

    Arachidonic acid (AA) is considered essential in fetal development and some of its metabolites are thought to be important mediators of the immune responses. Therefore, we studied whether prenatal exposure to AA is associated with some immune-related clinical conditions and plasma markers in childhood. In 280 children aged 7 years, atopy, lung function and plasma inflammation markers were measured and their relationships with early AA exposure were studied by linear and logistic regression analyses. AA exposure was deduced from AA concentrations in plasma phospholipids of the mothers collected at several time points during pregnancy and at delivery, and in umbilical cord plasma and arterial and venous wall phospholipids. In unadjusted regression analyses, significant positive associations were observed between maternal AA concentrations at 16 and 32 weeks of pregnancy (proxies for fetal AA exposure) and peak expiratory flow decline after maximal physical exercise and plasma fibrinogen concentrations of their children, respectively. However, after correction for relevant covariables, only trends remained. A significant negative relationship was observed between AA concentrations in cord plasma (reflecting prenatal AA exposure) and the average daily amplitude of peak expiratory flow at rest, which lost significance after appropriate adjustment. Because of these few, weak and inconsistent relationships, a major impact of early-life exposure to AA on atopy, lung function and selected plasma inflammation markers of children at 7 years of age seems unlikely. PMID:19173768

  14. Journey-time exposure to particulate air pollution

    NASA Astrophysics Data System (ADS)

    Gulliver, John; Briggs, David J.

    Journey-time exposures to particulate air pollution were investigated in Leicester, UK, between January and March 2005. Samples of TSP, PM 10, PM 2.5, and PM 1 were simultaneously collected using light scattering devices whilst journeys were made by walking an in-car. Over a period of two months, 33 pairs of walking and in-car measurements were collected along two circular routes. Average exposures while walking were seen to be higher than those found in-car for each of the particle fractions: average walking to in-car ratios were 1.2 (± 0.6), 1.5 (± 0.6), 1.3 (± 0.6), and 1.4 (± 0.6) μg m -3 for coarse (TSP-PM 10), intermediate (PM 10-PM 2.5), fine (PM 2.5-PM 1), and very fine particles (PM 1), respectively. Correlations between walking and in-car exposures were seen to be weak for coarse particles ( r=0.10, p=0.58), moderate for the intermediate particles ( r=0.49, p<0.01) but strong for fine ( r=0.89, p<0.01) and very fine ( r=0.90, P<0.01) particles. PM 10 exposures while walking were on average 70% higher than a nearby roadside fixed-site monitor whilst in-car exposures were 25% higher than the same fixed-site monitor. Particles with an aerodynamic diameter of less than 2.5 μm were seen to be highly correlated between walking and in-car particle exposures and a rural fixed-site monitor about 30 km south of Leicester.

  15. Exposure of two upland plant species to acidic fogs.

    PubMed

    Ashenden, T W; Rafarel, C R; Bell, S A

    1991-01-01

    A system is described for exposing large numbers of plants to acidic fogs. The system allows low volumes of treatment solutions to be provided at particle sizes chiefly in the 5-30 microm range (equivalent to fog/cloud droplets). Plants of Poa alpina L. and Epilobium brunnescens were propagated from material collected in Snowdonia, North Wales and exposed to fog treatments at pH values of 2.5, 3.5, 4.5 and 5.6. There were 3 x 4 h exposures per week which provided a total of 6 mm deposition. Supplementary watering was with pH 4.5 simulated acid rain (24 mm per week). After 21 weeks, there was increased lowering and a greater dry weight for plants of E. brunnescens exposed to the pH 2.5 fog in comparison with other treatments. Also, the plants used assimilated material to form shoots rather than roots. A similar increase in dry weight accumulation in the pH 2.5 treatment was found in P. alpina after 63 weeks but this was not associated with changes in assimilate partitioning.

  16. TIME-INTEGRATED EXPOSURE MEASURES TO IMPROVE THE PREDICTIVE POWER OF EXPOSURE CLASSIFICATION FOR EPIDEMIOLOGIC STUDIES

    EPA Science Inventory

    Accurate exposure classification tools are required to link exposure with health effects in epidemiological studies. Although long-term integrated exposure measurements are a critical component of exposure assessment, the ability to include these measurements into epidemiologic...

  17. Alkyl protocatechuates as novel urinary biomarkers of exposure to p-hydroxybenzoic acid esters (parabens).

    PubMed

    Wang, Lei; Kannan, Kurunthachalam

    2013-09-01

    Human exposure to p-hydroxybenzoic acid esters (parabens) is a concern, owing to adverse health effects of these compounds. Parabens are metabolized and eliminated from the human bodies within a few hours of exposure. In this study, for the first time, methyl- and ethyl-protocatechuates (OH-MeP and OH-EtP) and their parent compounds, methyl- (MeP) and ethyl-parabens (EtP), were determined in urine samples collected from U.S. children and adults. Alkyl protocatechuates were found in almost all urine samples, with median concentrations of 11.8 (OH-MeP) and 2.90ng/mL (OH-EtP) in adults, and 5.43 (OH-MeP) and 0.85ng/mL (OH-EtP) in children. In adults, the concentrations of urinary OH-MeP and OH-EtP were higher than the corresponding concentrations of MeP and EtP. Significant correlation between OH-MeP/OH-EtP and MeP/EtP was observed. This is the first report to document hydroxylation of parabens in humans, and to propose hydroxylated metabolites (i.e., alkyl protocatechuates) as alternative biomarkers of exposure to parabens in human biomonitoring studies. The rates of transformation of parabens between children and adults appeared to be different, as evidenced from the slopes of regression between alkyl protocatechuates and parabens. In addition to alkyl protocatechuates, hydroxybenzoic acid (4-HB) and 3,4-dihydroxybenzoic acid (3,4-DHB) were found at considerable levels in the urine samples. The occurrence of a significant proportion of alkyl protocatechuates and 3,4-DHB suggests the need for inclusion of these derivatives in accurate estimation of human exposure to parabens and in epidemiological studies that associate paraben exposure to health outcomes in populations.

  18. Management of a Patient With Faciocervical Burns and Inhalational Injury Due to Hydrofluoric Acid Exposure.

    PubMed

    Yuanhai, Zhang; Xingang, Wang; Liangfang, Ni; Chunmao, Han

    2014-05-01

    Hydrofluoric acid, a highly dangerous substance, can cause tissue damage and systemic toxicity by its unique mechanisms. Many cases of severe faciocervical burns due to hydrofluoric acid exposure are lethal. Herein, we present a case of 37-year-old man who suffered from hydrofluoric acid burns to his face, anterior neck, lips, and nasal cavity. On admission, this patient coughed with much sputum, and the chest auscultation detected rough breath sounds, wheezes, and very weak heart sounds, indicating possible inhalation injury. This case highlights the extreme complexity of managing this kind of injury. Timely and accurate wound treatment and respiratory tract care, as well as active systematic support treatment, played vital roles in the management of this patient.

  19. Respiratory hazards associated with exposure to formaldehyde and solvents in acid-curing paints

    SciTech Connect

    Alexandersson, R.; Hedenstierna, G.

    1988-05-01

    Thirty-eight employees exposed to formaldehyde when working with acid-hardening lacquers and 18 nonexposed control persons employed at the same company were examined to determine lung function (spirometry and nitrogen washout), total immunoglobulin blood concentration, and work-related symptoms. The mean exposure to formaldehyde during an 8-hr workshop was 0.40 mg/m/sup 3/ air, and the mean exposure to peak values was 0.70 mg/m/sup 3/. Mean exposure to solvents was low, i.e., approximately 1/10 of the hygienic effect. Eye, nose, and throat irritation was more common in exposed persons than in controls. Monday morning, after two exposure-free days, forced vital capacity (FVC) values were found to have declined by 0.24 L and forced expiratory volume in 1 sec (FEV/sub 1.0/) by 0.21 L, compared with normal values. There was a weak correlation between the individual concentration of IgG and decrease in FVC and FEV/sub 1.0/. No significant changes were noted in any other lung function variable before a work shift, and no lung function changes were noted over a full work shift. Deviations in FVC and FEV/sub 1.0/ values did not correlate to peaks or mean exposures or employment time.

  20. Chronic low-level domoic acid exposure alters gene transcription and impairs mitochondrial function in the CNS

    PubMed Central

    Hiolski, Emma M; Kendrick, Preston S; Frame, Elizabeth R; Myers, Mark S; Bammler, Theo K; Beyer, Richard P; Farin, Federico M; Wilkerson, Hui-wen; Smith, Donald R; Marcinek, David J; Lefebvre, Kathi A

    2014-01-01

    Domoic acid is an algal-derived seafood toxin that functions as a glutamate agonist and exerts excitotoxicity via overstimulation of glutamate receptors (AMPA, NMDA) in the central nervous system (CNS). At high (symptomatic) doses, domoic acid is well-known to cause seizures, brain lesions and memory loss; however, a significant knowledge gap exists regarding the health impacts of repeated low-level (asymptomatic) exposure. Here, we investigated the impacts of low-level repetitive domoic acid exposure on gene transcription and mitochondrial function in the vertebrate CNS using a zebrafish model in order to: 1) identify transcriptional biomarkers of exposure; and 2) examine potential pathophysiology that may occur in the absence of overt excitotoxic symptoms. We found that transcription of genes related to neurological function and development were significantly altered, and that asymptomatic exposure impaired mitochondrial function. Interestingly, the transcriptome response was highly-variable across the exposure duration (36 weeks), with little to no overlap of specific genes across the six exposure time points (2, 6, 12, 18, 24, and 36 weeks). Moreover, there were no apparent similarities at any time point with the gene transcriptome profile exhibited by the glud1 mouse model of chronic moderate excess glutamate release. These results suggest that although the fundamental mechanisms of toxicity may be similar, gene transcriptome responses to domoic acid exposure do not extrapolate well between different exposure durations. However, the observed impairment of mitochondrial function based on respiration rates and mitochondrial protein content suggests that repetitive low-level exposure does have fundamental cellular level impacts that could contribute to chronic health consequences. PMID:25033243

  1. Indoor exposures to fine aerosols and acid gases.

    PubMed

    Koutrakis, P; Brauer, M; Briggs, S L; Leaderer, B P

    1991-11-01

    Indoor exposures to aerosols and gases are associated with both indoor and outdoor air pollution sources. The identification of sources and the assessment of their relative contribution can be a complicated process due to a) the presence of numerous indoor sources, which can vary from building to building; b) the uncertainties associated with the estimation of the impact of outdoor sources on indoor air quality; c) the interactions between pollutants; and d) the importance of reactions between pollutants and indoor surfaces. It is well established that fine particles (diameter less than or equal to 2.5 microns) originating from outdoor sources such as automobiles, oil and coal combustion, incineration, and diverse industrial activities can penetrate into the indoor environment. Indoor/outdoor ratios, usually varying between 0.4 and 0.8, depend on parameters such as particle size and density, air exchange rate, and the surface-to-volume ratio of the indoor environment. Determining fine particle elemental composition makes it possible to identify the contribution of different outdoor sources. This paper focuses on the origin and the concentration of indoor aerosols and acid gases by highlighting the results from two indoor air quality studies. PMID:1821374

  2. ETC-42 Exposure Time Calculator: Evolution and New Functionalities

    NASA Astrophysics Data System (ADS)

    Gross, A.; Meunier, J. C.; Surace, C.; Apostolakos, N.

    2015-09-01

    We developed at CeSAM (Centre de donnees Astrophysiques de Marseille) ETC-42, an Exposure Time Calculator compliant with Virtual Observatory standards. ETC-42 has been designed to facilitate the integration of new sites, instruments and sources by the user. It is not instrument-specific, but is based on generic XML input data. It is used in several project implementations (EUCLID, PFS, IRIS, WISH, EELTs) covering a wide wavelength range, from NIR to UV. The previous release has been optimized to achieve gain of computation time. New functionalities for automatic input parameterization have been added to target specific instrumental configuration and to give an increased level of user-friendliness. This article describes the new functionalities : fixtures, sdaptive optics, Fabry Perot implementation and two new builder tools to create Telescope transmission curves and sky brightness tables. And, in order to facilitate the integration to the Virtual Observatory environment, VO drag and drop functionality is now available.

  3. Promotion time models with time-changing exposure and heterogeneity: application to infectious diseases.

    PubMed

    Tournoud, Maud; Ecochard, René

    2008-06-01

    Promotion time models have been recently adapted to the context of infectious diseases to take into account discrete and multiple exposures. However, Poisson distribution of the number of pathogens transmitted at each exposure was a very strong assumption and did not allow for inter-individual heterogeneity. Bernoulli, the negative binomial, and the compound Poisson distributions were proposed as alternatives to Poisson distribution for the promotion time model with time-changing exposure. All were derived within the frailty model framework. All these distributions have a point mass at zero to take into account non-infected people. Bernoulli distribution, the two-component cure rate model, was extended to multiple exposures. Contrary to the negative binomial and the compound Poisson distributions, Bernoulli distribution did not enable to connect the number of pathogens transmitted to the delay between transmission and infection detection. Moreover, the two former distributions enable to account for inter-individual heterogeneity. The delay to surgical site infection was an example of single exposure. The probability of infection was very low; thus, estimation of the effect of selected risk factors on that probability obtained with Bernoulli and Poisson distributions were very close. The delay to nosocomial urinary tract infection was a multiple exposure example. The probabilities of pathogen transmission during catheter placement and catheter presence were estimated. Inter-individual heterogeneity was very high, and the fit was better with the compound Poisson and the negative binomial distributions. The proposed models proved to be also mechanistic. The negative binomial and the compound Poisson distributions were useful alternatives to account for inter-individual heterogeneity. PMID:18435501

  4. Inattentional blindness is influenced by exposure time not motion speed.

    PubMed

    Kreitz, Carina; Furley, Philip; Memmert, Daniel

    2016-01-01

    Inattentional blindness is a striking phenomenon in which a salient object within the visual field goes unnoticed because it is unexpected, and attention is focused elsewhere. Several attributes of the unexpected object, such as size and animacy, have been shown to influence the probability of inattentional blindness. At present it is unclear whether or how the speed of a moving unexpected object influences inattentional blindness. We demonstrated that inattentional blindness rates are considerably lower if the unexpected object moves more slowly, suggesting that it is the mere exposure time of the object rather than a higher saliency potentially induced by higher speed that determines the likelihood of its detection. Alternative explanations could be ruled out: The effect is not based on a pop-out effect arising from different motion speeds in relation to the primary-task stimuli (Experiment 2), nor is it based on a higher saliency of slow-moving unexpected objects (Experiment 3). PMID:26031845

  5. Influence of the Exposure Time after Removing of Covering Materials over Shading Tea Field on the Quality of Gyokuro

    NASA Astrophysics Data System (ADS)

    Sakaida, Teruki; Yoshioka, Tetsuya; Nitabaru, Juichi; Nakazono, Kentaro; Kubota, Akira; Nariyama, Hideki

    We revealed the influences of the exposure time after removing of covering materials over shading tea field for making gyokuro on the quality of made tea. As the exposure time increased, the green color of the fresh leaves faded; their total amino acid and theanine contents reduced; and the concentration of dimethyl sulfide, a representative aromatic compound in gyokuro, decreased. In contrast, the catechin content increased. The overall quality of the tea was lowered. These results indicated it was necessary to plucking of tea shoots for short time after removing of covering materials over shading tea field.

  6. Effects of ascorbic acid supplementation on male reproductive system during exposure to hypoxia

    NASA Astrophysics Data System (ADS)

    Havazhagan, G.; Riar, S. S.; Kain, A. K.; Bardhan, Jaya; Thomas, Pauline

    1989-09-01

    Two groups of male rats were exposed to simulated altitudes of 6060 m and 7576 m for 6 h/day for 7 days (intermittent exposure). In two additional groups of animals exposed to the same altitude, 100 mg of ascorbic acid (AA) was fed daily for 5 days prior to the exposure period and also during the exposure period. Rats that did not receive AA showed loss of body weight and weight of reproductive organs after exposure. Sex organs showed atrophy on histological examination and there was a deterioration in spermatozoal quality. There was an increase in alkaline and acid phosphatase, and decrease in protein, sialic acid and glyceryl phosphorylcholine content in various reproductive tissues after exposure. All the above changes in histology and biochemical composition could be partially prevented by AA supplementation. AA supplementation can therefore protect the male reproductive system from deleterious effects of hypoxia. The probable mechanism of action of AA is discussed.

  7. Making Time for Nature: Visual Exposure to Natural Environments Lengthens Subjective Time Perception and Reduces Impulsivity

    PubMed Central

    Berry, Meredith S.; Repke, Meredith A.; Nickerson, Norma P.; Conway, Lucian G.; Odum, Amy L.; Jordan, Kerry E.

    2015-01-01

    Impulsivity in delay discounting is associated with maladaptive behaviors such as overeating and drug and alcohol abuse. Researchers have recently noted that delay discounting, even when measured by a brief laboratory task, may be the best predictor of human health related behaviors (e.g., exercise) currently available. Identifying techniques to decrease impulsivity in delay discounting, therefore, could help improve decision-making on a global scale. Visual exposure to natural environments is one recent approach shown to decrease impulsive decision-making in a delay discounting task, although the mechanism driving this result is currently unknown. The present experiment was thus designed to evaluate not only whether visual exposure to natural (mountains, lakes) relative to built (buildings, cities) environments resulted in less impulsivity, but also whether this exposure influenced time perception. Participants were randomly assigned to either a natural environment condition or a built environment condition. Participants viewed photographs of either natural scenes or built scenes before and during a delay discounting task in which they made choices about receiving immediate or delayed hypothetical monetary outcomes. Participants also completed an interval bisection task in which natural or built stimuli were judged as relatively longer or shorter presentation durations. Following the delay discounting and interval bisection tasks, additional measures of time perception were administered, including how many minutes participants thought had passed during the session and a scale measurement of whether time "flew" or "dragged" during the session. Participants exposed to natural as opposed to built scenes were less impulsive and also reported longer subjective session times, although no differences across groups were revealed with the interval bisection task. These results are the first to suggest that decreased impulsivity from exposure to natural as opposed to built

  8. Making Time for Nature: Visual Exposure to Natural Environments Lengthens Subjective Time Perception and Reduces Impulsivity.

    PubMed

    Berry, Meredith S; Repke, Meredith A; Nickerson, Norma P; Conway, Lucian G; Odum, Amy L; Jordan, Kerry E

    2015-01-01

    Impulsivity in delay discounting is associated with maladaptive behaviors such as overeating and drug and alcohol abuse. Researchers have recently noted that delay discounting, even when measured by a brief laboratory task, may be the best predictor of human health related behaviors (e.g., exercise) currently available. Identifying techniques to decrease impulsivity in delay discounting, therefore, could help improve decision-making on a global scale. Visual exposure to natural environments is one recent approach shown to decrease impulsive decision-making in a delay discounting task, although the mechanism driving this result is currently unknown. The present experiment was thus designed to evaluate not only whether visual exposure to natural (mountains, lakes) relative to built (buildings, cities) environments resulted in less impulsivity, but also whether this exposure influenced time perception. Participants were randomly assigned to either a natural environment condition or a built environment condition. Participants viewed photographs of either natural scenes or built scenes before and during a delay discounting task in which they made choices about receiving immediate or delayed hypothetical monetary outcomes. Participants also completed an interval bisection task in which natural or built stimuli were judged as relatively longer or shorter presentation durations. Following the delay discounting and interval bisection tasks, additional measures of time perception were administered, including how many minutes participants thought had passed during the session and a scale measurement of whether time "flew" or "dragged" during the session. Participants exposed to natural as opposed to built scenes were less impulsive and also reported longer subjective session times, although no differences across groups were revealed with the interval bisection task. These results are the first to suggest that decreased impulsivity from exposure to natural as opposed to built

  9. TOXICOGENOMIC DISSECTION OF RODENT LIVER TRANSCRIPT PROFILES AFTER EXPOSURE TO PERFLUOROALKYL ACIDS

    EPA Science Inventory

    Exposure to peroxisome proliferator chemicals (PPC) leads to alterations in the balance between hepatocyte growth and apoptosis, increases in liver to body weight ratios and liver tumors. The perfluoroalkyl acids including perfluorooctanoate (PFOA) and perfluorooctane sulfonate (...

  10. Examination of age-related epigenetic changes following early-life exposure to dichloroacetic acid

    EPA Science Inventory

    Recent studies have shown that transient early-life exposure to dichloroacetic acid (DCA), a pyruvate analog and metabolic reprogramming agent, increases liver cancer incidence in older mice. This carcinogenic effect is not associated with direct mutagenicity, persistent cytotoxi...

  11. Hydrofluoric acid exposure: a case report and review on the clinical presentation and management.

    PubMed

    Strausburg, Matthew; Travers, Jeffrey; Mousdicas, Nico

    2012-01-01

    Exposure to hydrofluoric acid can cause severe skin damage via both corrosive and chemical means. Dermatologists should be aware of the various clinical presentations and knowledgeable of how to manage such patients. A case of a man with exposure of the hands after use of a consumer product containing hydrofluoric acid is presented. The presentation may vary depending on the concentration and duration of exposure. Patients experiencing exposure are at risk of serious complications, including death, resulting from electrolyte abnormalities. Information regarding the source of exposure will allow the physician to better predict the patient's course. The use of immediate flushing with water and the use of topical calcium gluconate can prevent extensive damage to the area of exposure and potentially fatal complications that may occur. More extensive burns may necessitate more invasive therapies. The treatment and the management and monitoring of such cases will allow for more optimal outcomes.

  12. The protective role of ascorbic acid on hippocampal CA1 pyramidal neurons in a rat model of maternal lead exposure.

    PubMed

    Sepehri, Hamid; Ganji, Farzaneh

    2016-07-01

    Oxidative stress is a major pathogenic mechanism of lead neurotoxicity. The antioxidant ascorbic acid protects hippocampal pyramidal neurons against cell death during congenital lead exposure; however, critical functions like synaptic transmission, integration, and plasticity depend on preservation of dendritic and somal morphology. This study was designed to examine if ascorbic acid also protects neuronal morphology during developmental lead exposure. Timed pregnant rats were divided into four treatment groups: (1) control, (2) 100mg/kg ascorbic acid once a day via gavage, (3) 0.05% lead acetate in drinking water, and (4) 0.05% lead+100mg/kg oral ascorbic acid. Brains of eight male pups (P25) per treatment group were processed for Golgi staining. Changes in hippocampal CA1 pyramidal neurons' somal size were estimated by cross-sectional area and changes in dendritic arborization by Sholl's analysis. One-way ANOVA was used to compare results among treatment groups. Lead-exposed pups exhibited a significant decrease in somal size compared to controls (P<0.01) that was reversed by cotreatment with ascorbic acid. Sholl's analysis revealed a significant increase in apical dendritic branch points near cell body (P<0.05) and a decreased total dendritic length in both apical and basal dendritic trees of CA1 neurons (P<0.05). Ascorbic acid significantly but only partially reversed the somal and dendritic damage caused by developmental lead exposure. Oxidative stress thus contributes to lead neurotoxicity but other pathogenic mechanisms are also involved.

  13. Acute exposure to acid fog: influence of breathing pattern on effective dose.

    PubMed

    Bowes, S M; Francis, M; Laube, B L; Frank, R

    1995-02-01

    Concern about the possible adverse health effects of acid fog has been fed by two observations: air pollution disasters earlier in this century were typically associated with fog, and current samples of fog water can be strongly acid. To study the acute effects of acid fog on the lung, the authors generated a monodisperse 10 microM MMAD aerosol of H2SO4 with a pH of 2.0 and a nominal concentration of 500 micrograms/m3. They exposed seven healthy young men on alternate days to acid or control equiosmolar NaCl aerosol during 40 min of resting ventilation and 20 min of exercise; the latter was sufficiently intense to induce oronasal breathing. Exposure was by means of a head dome, a head-only exposure device that permitted continuous measurement (unfettered breathing) of Vr, f, VE, and the onset and persistence of oronasal breathing. In this article the authors compare the relative importance of parameters contributing to the between-subject variability in estimated hydrogen ion dose to the lower airways (H+LAW), based on analysis of variance. Physiologic parameters accounted for 70% of the variability, of which 34% was due to differences in duration of oronasal breathing (tON) and 36% to differences in ventilation rate during oronasal breathing (VE(ON)); inhaled hydrogen ion concentration [H+], the environmental parameter, contributed only 30%. Minute ventilation at the time of transition from nasal to oronasal breathing varied significantly among subjects even if normalized to FVC, an index of lung size.

  14. Acute lung injury following exposure to nitric acid

    PubMed Central

    Jayalakshmi, T. K.; Shah, Samir; Lobo, Ivona; Uppe, Abhay; Mehta, Ankur

    2009-01-01

    We present a series of three cases of survival following inhalation of nitric acid fumes, which resulted in acute respiratory distress. Inhalation of nitric acid fumes and its decomposition gases such as nitrogen dioxide results in delayed onset of acute respiratory distress syndrome. Intensive respiratory management, ventilatory support, and steroids can help in survival. PMID:20532002

  15. Continuous exposure to dibromoacetic acid delays pubertal development and compromises sperm quality in the rat

    EPA Science Inventory

    Previously our work on the haloacid by-products of drinking water disinfection focused on adult exposures. Herein we evaluate the consequence of continuous exposure to dibromoacetic acid (DBA) via drinking water through reproductive development into adulthood. An initial study in...

  16. Lower pH values of weakly acidic refluxes as determinants of heartburn perception in gastroesophageal reflux disease patients with normal esophageal acid exposure.

    PubMed

    de Bortoli, N; Martinucci, I; Savarino, E; Franchi, R; Bertani, L; Russo, S; Ceccarelli, L; Costa, F; Bellini, M; Blandizzi, C; Savarino, V; Marchi, S

    2016-01-01

    Multichannel impedance pH monitoring has shown that weakly acidic refluxes are able to generate heartburn. However, data on the role of different pH values, ranging between 4 and 7, in the generation of them are lacking. The aim of this study was to evaluate whether different pH values of weakly acidic refluxes play a differential role in provoking reflux symptoms in endoscopy-negative patients with physiological esophageal acid exposure time and positive symptom index and symptom association probability for weakly acidic refluxes. One hundred and forty-three consecutive patients with gastroesophageal reflux disease, nonresponders to proton pump inhibitors (PPIs), were allowed a washout from PPIs before undergoing: upper endoscopy, esophageal manometry, and multichannel impedance pH monitoring. In patients with both symptom index and symptom association probability positive for weakly acidic reflux, each weakly acidic reflux was evaluated considering exact pH value, extension, physical characteristics, and correlation with heartburn. Forty-five patients with normal acid exposure time and positive symptom association probability for weakly acidic reflux were identified. The number of refluxes not heartburn related was higher than those heartburn related. In all distal and proximal liquid refluxes, as well as in distal mixed refluxes, the mean pH value of reflux events associated with heartburn was significantly lower than that not associated. This condition was not confirmed for proximal mixed refluxes. Overall, a low pH of weakly acidic reflux represents a determinant factor in provoking heartburn. This observation contributes to better understand the pathophysiology of symptoms generated by weakly acidic refluxes, paving the way toward the search for different therapeutic approaches to this peculiar condition of esophageal hypersensitivity.

  17. Detailed Urinary Excretion Time Courses of Biomarkers of Exposure to Permethrin and Estimated Exposure in Workers of a Corn Production Farm in Quebec, Canada.

    PubMed

    Ferland, Stéphanie; Côté, Jonathan; Ratelle, Mylène; Thuot, Ross; Bouchard, Michèle

    2015-11-01

    Permethrin is a synthetic pyrethroid insecticide widely used in agriculture. Farm workers are thus regularly exposed during spraying season. To help interpret routine biomonitoring results, a proper knowledge of the time courses of biomarkers of exposure is necessary. The kinetics of biomarkers of exposure to permethrin has recently been documented in volunteers exposed to permethrin under controlled conditions but there is a lack of detailed time profiles following real exposure conditions. This study aimed at obtaining data on the excretion time courses of permethrin metabolites in agricultural workers following typical exposure conditions in the field. Twelve workers exposed to permethrin were recruited from a corn production farm in the Montérégie, Quebec, Canada. They provided all their urine voided over a period of 3 days following the onset of a spraying episode of permethrin or work in a treated area. Three major metabolites of permethrin, trans- and cis- 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-l-carboxylic acid metabolites (trans-DCCA, cis-DCCA), and 3-phenoxybenzoic acid (3-PBA), were analyzed. For the applicator, a progressive rise in excretion values was observed with a single peak being reached 29h following the onset of the 3.5h exposure and ensuing elimination with a half-life of 6.4h for trans-DCCA and 8.7h for 3-PBA. In the other workers (supervisor and corn pickers), excretion profiles were generally more compatible with multiple entries in the treated area during the 3-day sampling period and rapid elimination between exposure episodes. In general, 3-PBA was found in slightly higher levels than trans-DCCA, except for the applicator and a harvester. For both trans-DCCA and 3-PBA in a given worker, excretion values expressed as creatinine-normalized concentrations were less variable than those expressed as excretion rates per kilogram body weight. Time-dependent variability in excretion values of workers confirms the need for serial urine

  18. The Exposure Experience: Ohio River Valley Residents Respond to Local Perfluorooctanoic Acid (PFOA) Contamination.

    PubMed

    Judge, J Matthew; Brown, Phil; Brody, Julia Green; Ryan, Serena

    2016-09-01

    This article explores the "exposure experience" of participants who received their personal results in a biomonitoring study for perfluorooctanoic acid. Exposure experience is the process of identifying, understanding, and responding to chemical contamination. When biomonitoring studies report results to participants, those participants generate an exposure experience that identifies hidden contaminants and helps level informational imbalances between polluters and affected communities. Participants welcomed the opportunity to learn their exposure results, reporting no psychological harm following report-back. They wove health, economic, and political considerations into their interpretation of results and their present views of past impact. Participants framed their experiences by a half-century of dependence on the chemical industry's economic benefits, leading them to considerable acceptance of chemical exposure as a tradeoff for jobs and the local economy. Our findings show that the exposure experience is an ongoing process that influences social action, with new activism being generated by exposure and health studies. PMID:27601409

  19. Night time aircraft noise exposure and children's cognitive performance.

    PubMed

    Stansfeld, Stephen; Hygge, Staffan; Clark, Charlotte; Alfred, Tamuno

    2010-01-01

    Chronic aircraft noise exposure in children is associated with impairment of reading and long-term memory. Most studies have not differentiated between day or nighttime noise exposure. It has been hypothesized that sleep disturbance might mediate the association of aircraft noise exposure and cognitive impairment in children. This study involves secondary analysis of data from the Munich Study and the UK Road Traffic and Aircraft Noise Exposure and Children's Cognition and Health (RANCH) Study sample to test this. In the Munich study, 330 children were assessed on cognitive measures in three measurement waves a year apart, before and after the switchover of airports. Self-reports of sleep quality were analyzed across airports, aircraft noise exposure and measurement wave to test whether changes in nighttime noise exposure had any effect on reported sleep quality, and whether this showed the same pattern as for changes in cognitive performance. For the UK sample of the RANCH study, night noise contour information was linked to the children's home and related to sleep disturbance and cognitive performance. In the Munich study, analysis of sleep quality questions showed no consistent interactions between airport, noise, and measurement wave, suggesting that poor sleep quality does not mediate the association between noise exposure and cognition. Daytime and nighttime aircraft noise exposure was highly correlated in the RANCH study. Although night noise exposure was significantly associated with impaired reading and recognition memory, once home night noise exposure was centered on daytime school noise exposure, night noise had no additional effect to daytime noise exposure. These analyses took advantage of secondary data available from two studies of aircraft noise and cognition. They were not initially designed to examine sleep disturbance and cognition, and thus, there are methodological limitations which make it less than ideal in giving definitive answers to these

  20. DOCOSAHEXAENOIC ACID PARTIALLY AMELIORATES DEFICITS IN SOCIAL BEHAVIOR AND ULTRASONIC VOCALIZATIONS CAUSED BY PRENATAL ETHANOL EXPOSURE

    PubMed Central

    Wellmann, Kristen A.; George, Finney; Brnouti, Fares; Mooney, Sandra M.

    2015-01-01

    Prenatal ethanol exposure disrupts social behavior in humans and rodents. One system particularly important for social behavior is the somatosensory system. Prenatal ethanol exposure alters the structure and function of this area. Docosahexaenoic acid (DHA), an omega 3 polyunsaturated fatty acid, is necessary for normal brain development and brains from ethanol-exposed animals are DHA deficient. Thus, we determined whether postnatal DHA supplementation ameliorated behavioral deficits induced by prenatal ethanol exposure. Timed pregnant Long-Evans rats were assigned to one of three groups: ad libitum access to an ethanol-containing liquid diet, pair fed an isocaloric isonutritive non-alcohol liquid diet, or ad libitum access to chow and water. Pups were assigned to one of two postnatal treatment groups; gavaged intragastrically once per day between postnatal day (P)11 and P20 with DHA (10 g/kg in artificial rat milk) or artificial rat milk. A third group was left untreated. Isolation-induced ultrasonic vocalizations (iUSVs) were recorded on P14. Social behavior and play-induced USVs were tested on P28 or P42. Somatosensory performance was tested with a gap crossing test around P33 or on P42. Anxiety was tested on elevated plus maze around P35. Animals exposed to ethanol prenatally vocalized less, play fought less, and crossed a significantly shorter gap than control-treated animals. Administration of DHA ameliorated these ethanol-induced deficits such that the ethanol-exposed animals given DHA were no longer significantly different to control-treated animals. Thus, DHA administration may have therapeutic value to reverse some of ethanol’s damaging effects. PMID:25746516

  1. Docosahexaenoic acid partially ameliorates deficits in social behavior and ultrasonic vocalizations caused by prenatal ethanol exposure.

    PubMed

    Wellmann, Kristen A; George, Finney; Brnouti, Fares; Mooney, Sandra M

    2015-06-01

    Prenatal ethanol exposure disrupts social behavior in humans and rodents. One system particularly important for social behavior is the somatosensory system. Prenatal ethanol exposure alters the structure and function of this area. Docosahexaenoic acid (DHA), an omega 3 polyunsaturated fatty acid, is necessary for normal brain development and brains from ethanol-exposed animals are DHA deficient. Thus, we determined whether postnatal DHA supplementation ameliorated behavioral deficits induced by prenatal ethanol exposure. Timed pregnant Long-Evans rats were assigned to one of three groups: ad libitum access to an ethanol-containing liquid diet, pair fed an isocaloric isonutritive non-alcohol liquid diet, or ad libitum access to chow and water. Pups were assigned to one of two postnatal treatment groups; gavaged intragastrically once per day between postnatal day (P)11 and P20 with DHA (10g/kg in artificial rat milk) or artificial rat milk. A third group was left untreated. Isolation-induced ultrasonic vocalizations (iUSVs) were recorded on P14. Social behavior and play-induced USVs were tested on P28 or P42. Somatosensory performance was tested with a gap crossing test around P33 or on P42. Anxiety was tested on elevated plus maze around P35. Animals exposed to ethanol prenatally vocalized less, play fought less, and crossed a significantly shorter gap than control-treated animals. Administration of DHA ameliorated these ethanol-induced deficits such that the ethanol-exposed animals given DHA were no longer significantly different to control-treated animals. Thus, DHA administration may have therapeutic value to reverse some of ethanol's damaging effects.

  2. Docosahexaenoic acid partially ameliorates deficits in social behavior and ultrasonic vocalizations caused by prenatal ethanol exposure.

    PubMed

    Wellmann, Kristen A; George, Finney; Brnouti, Fares; Mooney, Sandra M

    2015-06-01

    Prenatal ethanol exposure disrupts social behavior in humans and rodents. One system particularly important for social behavior is the somatosensory system. Prenatal ethanol exposure alters the structure and function of this area. Docosahexaenoic acid (DHA), an omega 3 polyunsaturated fatty acid, is necessary for normal brain development and brains from ethanol-exposed animals are DHA deficient. Thus, we determined whether postnatal DHA supplementation ameliorated behavioral deficits induced by prenatal ethanol exposure. Timed pregnant Long-Evans rats were assigned to one of three groups: ad libitum access to an ethanol-containing liquid diet, pair fed an isocaloric isonutritive non-alcohol liquid diet, or ad libitum access to chow and water. Pups were assigned to one of two postnatal treatment groups; gavaged intragastrically once per day between postnatal day (P)11 and P20 with DHA (10g/kg in artificial rat milk) or artificial rat milk. A third group was left untreated. Isolation-induced ultrasonic vocalizations (iUSVs) were recorded on P14. Social behavior and play-induced USVs were tested on P28 or P42. Somatosensory performance was tested with a gap crossing test around P33 or on P42. Anxiety was tested on elevated plus maze around P35. Animals exposed to ethanol prenatally vocalized less, play fought less, and crossed a significantly shorter gap than control-treated animals. Administration of DHA ameliorated these ethanol-induced deficits such that the ethanol-exposed animals given DHA were no longer significantly different to control-treated animals. Thus, DHA administration may have therapeutic value to reverse some of ethanol's damaging effects. PMID:25746516

  3. A MULTISTAGE BIOLOGICALLY BASED MODEL FOR MOUSE LIVER TUMORS RESULTING FROM EXPOSURE TO DICHLOROACETIC ACID

    EPA Science Inventory

    Dichloroacetic Acid (DCA) is a major byproduct of the chlorine disinfection of humic acid containing drinking water sources. It is a hepatocarcinogen in mice and rats at exposure concentrations in drinking water that are at least 4 orders of magnitude above the concentrations in ...

  4. PERFLUOROOCTANOIC ACID AND PERFLUORONONANOIC ACID IN FETAL AND NEONATAL MICE FOLLOWING IN UTERO EXPOSURE TO 8-2 FLUOROTELOMER ALCOHOL

    EPA Science Inventory

    8-2 fluorotelomer alcohol (FTOH) and its metabolites, perfluorooctanoic acid (PFOA) and perfluorononanoic acid (PFNA), are developmental toxicants, but metabolism and distribution during pregnancy is not known. To examine this, timed-pregnant mice received a single gavage dose (...

  5. Understanding Potential Exposure Sources of Perfluorinated Carboxylic Acids in the Workplace

    PubMed Central

    Kaiser, Mary A.; Dawson, Barbara J.; Barton, Catherine A.; Botelho, Miguel A.

    2010-01-01

    This paper integrates perspectives from analytical chemistry, environmental engineering, and industrial hygiene to better understand how workers may be exposed to perfluorinated carboxylic acids when handling them in the workplace in order to identify appropriate exposure controls. Due to the dramatic difference in physical properties of the protonated acid form and the anionic form, this family of chemicals provides unique industrial hygiene challenges. Workplace monitoring, experimental data, and modeling results were used to ascertain the most probable workplace exposure sources and transport mechanisms for perfluorooctanoic acid (PFOA) and its ammonium salt (APFO). PFOA is biopersistent and its measurement in the blood has been used to assess human exposure since it integrates exposure from all routes of entry. Monitoring suggests that inhalation of airborne material may be an important exposure route. Transport studies indicated that, under low pH conditions, PFOA, the undissociated (acid) species, actively partitions from water into air. In addition, solid-phase PFOA and APFO may also sublime into the air. Modeling studies determined that contributions from surface sublimation and loss from low pH aqueous solutions can be significant potential sources of workplace exposure. These findings suggest that keeping surfaces clean, preventing accumulation of material in unventilated areas, removing solids from waste trenches and sumps, and maintaining neutral pH in sumps can lower workplace exposures. PMID:20974675

  6. Time profiles and toxicokinetic parameters of key biomarkers of exposure to cypermethrin in orally exposed volunteers compared with previously available kinetic data following permethrin exposure.

    PubMed

    Ratelle, Mylène; Coté, Jonathan; Bouchard, Michèle

    2015-12-01

    Biomonitoring of pyrethroid exposure is largely conducted but human toxicokinetics has not been fully documented. This is essential for a proper interpretation of biomonitoring data. Time profiles and toxicokinetic parameters of key biomarkers of exposure to cypermethrin in orally exposed volunteers have been documented and compared with previously available kinetic data following permethrin dosing. Six volunteers ingested 0.1 mg kg(-1) bodyweight of cypermethrin acutely. The same volunteers were exposed to permethrin earlier. Blood samples were taken over 72 h after treatment and complete timed urine voids were collected over 84 h postdosing. Cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acids (trans- and cis-DCCA) and 3-phenoxybenzoic acid (3-PBA) metabolites, common to both cypermethrin and permethrin, were quantified. Blood and urinary time courses of all three metabolites were similar following cypermethrin and permethrin exposure. Plasma levels of metabolites reached peak values on average ≈ 5-7 h post-dosing; the elimination phase showed mean apparent half-lives (t½ ) for trans-DCCA, cis-DCCA and 3-PBA of 5.1, 6.9 and 9.2 h, respectively, following cypermethrin treatment as compared to 7.1, 6.2 and 6.5 h after permethrin dosing. Corresponding mean values obtained from urinary rate time courses were peak values at ≈ 9 h post-dosing and apparent elimination t½ of 6.3, 6.4 and 6.4 h for trans-DCCA, cis-DCCA and 3-PBA, respectively, following cypermethrin treatment as compared to 5.4, 4.5 and 5.7 h after permethrin dosing. These data confirm that the kinetics of cypermethrin is similar to that of permethrin in humans and that their common biomarkers of exposure may be used for an overall assessment of exposure.

  7. Effects of developmental alcohol and valproic acid exposure on play behavior of ferrets.

    PubMed

    Krahe, Thomas E; Filgueiras, Claudio C; Medina, Alexandre E

    2016-08-01

    Exposure to alcohol and valproic acid (VPA) during pregnancy can lead to fetal alcohol spectrum disorders and fetal valproate syndrome, respectively. Altered social behavior is a hallmark of both these conditions and there is ample evidence showing that developmental exposure to alcohol and VPA affect social behavior in rodents. However, results from rodent models are somewhat difficult to translate to humans owing to the substantial differences in brain development, morphology, and connectivity. Since the cortex folding pattern is closely related to its specialization and that social behavior is strongly influenced by cortical structures, here we studied the effects of developmental alcohol and VPA exposure on the play behavior of the ferret, a gyrencephalic animal known for its playful nature. Animals were injected with alcohol (3.5g/kg, i.p.), VPA (200mg/kg, i.p.) or saline (i.p) every other day during the brain growth spurt period, between postnatal days 10 and 30. The play behavior of pairs of the same experimental group was evaluated 3 weeks later. Both treatments induced significant behavioral differences compared to controls. Alcohol and VPA exposed ferrets played less than saline treated ones, but while animals from the alcohol group displayed a delay in start playing with each other, VPA treated ones spent most of the time close to one another without playing. These findings not only extend previous results on the effects of developmental exposure to alcohol and VPA on social behavior, but make the ferret a great model to study the underlying mechanisms of social interaction. PMID:27208641

  8. Predictors of 2,4-dichlorophenoxyacetic acid exposure among herbicide applicators.

    PubMed

    Bhatti, Parveen; Blair, Aaron; Bell, Erin M; Rothman, Nathaniel; Lan, Qing; Barr, Dana B; Needham, Larry L; Portengen, Lutzen; Figgs, Larry W; Vermeulen, Roel

    2010-03-01

    To determine the major factors affecting the urinary levels of 2,4-dichlorophenoxyacetic acid (2,4-D) among county noxious weed applicators in Kansas, we used a regression technique that accounted for multiple days of exposure. We collected 136 12-h urine samples from 31 applicators during the course of two spraying seasons (April to August of 1994 and 1995). Using mixed-effects models, we constructed exposure models that related urinary 2,4-D measurements to weighted self-reported work activities from daily diaries collected over 5 to 7 days before the collection of the urine sample. Our primary weights were based on an earlier pharmacokinetic analysis of turf applicators; however, we examined a series of alternative weighting schemes to assess the impact of the specific weights and the number of days before urine sample collection that were considered. The derived models accounting for multiple days of exposure related to a single urine measurement seemed robust with regard to the exact weights, but less to the number of days considered; albeit the determinants from the primary model could be fitted with marginal losses of fit to the data from the other weighting schemes that considered a different numbers of days. In the primary model, the total time of all activities (spraying, mixing, other activities), spraying method, month of observation, application concentration, and wet gloves were significant determinants of urinary 2,4-D concentration and explained 16% of the between-worker variance and 23% of the within-worker variance of urinary 2,4-D levels. As a large proportion of the variance remained unexplained, further studies should be conducted to try to systematically assess other exposure determinants.

  9. Selective agonists of retinoic acid receptors: comparative toxicokinetics and embryonic exposure.

    PubMed

    Arafa, H M; Elmazar, M M; Hamada, F M; Reichert, U; Shroot, B; Nau, H

    2000-01-01

    Three biologically active synthetic retinoids were investigated that bind selectively to retinoic acid receptors RARs (alpha, beta and gamma). The retinoids were previously demonstrated to have different teratogenic effects in the mouse in terms of potency and regioselectivity. The teratogenic potency rank order (alpha >beta >gamma) was found to be more or less compatible with the receptor binding affinities and transactivation potencies of the retinoid ligands to their respective receptors. The RARalpha agonist (Am580; CD336) induced a wide spectrum of malformations; CD2019 (RARbeta agonist) and especially CD437 (RARgamma agonist) produced more restricted defects. In the current study we tried to address whether the differences in teratogenic effects are solely related to binding affinity and transactivation differences or also due to differences in embryonic exposure. Therefore, transplacental kinetics of the ligands were assessed following administration of a single oral dose of 15 mg/kg of either retinoid given to NMRI mice on day 11 of gestation. Am580 was rapidly transferred to the embryo resulting in the highest embryonic exposure [embryo to maternal plasma area under the time vs concentration curve (AUC)(0-24 h )ratio (E/M) was 1.7], in accordance with its highest teratogenic potency. The low placental transfer of CD2019 (E/M of 0.3) was compatible with its lower teratogenic potential. Of major interest was the finding that the CD437, though being least teratogenic, exhibited considerable embryonic exposure (E/M of 0.6). These findings suggest that both the embryonic exposure and receptor binding transactivation selectivity are crucial determinants of the teratogenicity of these retinoid ligands.

  10. Terahertz time-domain spectroscopy of four hydroxycinnamic acid derivatives.

    PubMed

    Ge, Min; Zhao, Hongwei; Wang, Wenfeng; Zhang, Zengyan; Yu, Xiaohan; Li, Wenxin

    2006-11-01

    The well-resolved absorption spectra of the hydroxycinnamic acid (HCA) derivatives, caffeic acid, ferulic acid, sinapic acid and chlorogenic acid, were measured over the frequency region from 0.3 to 2.0 THz at 294 K with terahertz time-domain spectroscopy (THz-TDS). Theoretical calculation was applied to assist the analysis and assignment of the individual THz absorption spectra of the HCA derivatives with density functional theory (DFT). The distinctive spectral features were originated from the collective motion of molecules held together by hydrogen bonds. The real and imaginary parts of dielectric function of the four HCA derivatives were also obtained. PMID:19669446

  11. Terahertz Time-Domain Spectroscopy of Four Hydroxycinnamic Acid Derivatives

    PubMed Central

    Ge, Min; Zhao, Hongwei; Zhang, Zengyan; Yu, Xiaohan; Li, Wenxin

    2006-01-01

    The well-resolved absorption spectra of the hydroxycinnamic acid (HCA) derivatives, caffeic acid, ferulic acid, sinapic acid and chlorogenic acid, were measured over the frequency region from 0.3 to 2.0 THz at 294 K with terahertz time-domain spectroscopy (THz-TDS). Theoretical calculation was applied to assist the analysis and assignment of the individual THz absorption spectra of the HCA derivatives with density functional theory (DFT). The distinctive spectral features were originated from the collective motion of molecules held together by hydrogen bonds. The real and imaginary parts of dielectric function of the four HCA derivatives were also obtained. PMID:19669446

  12. Phenolic acid metabolites as biomarkers for tea- and coffee-derived polyphenol exposure in human subjects.

    PubMed

    Hodgson, Jonathan M; Chan, Shin Yee; Puddey, Ian B; Devine, Amanda; Wattanapenpaiboon, Naiyana; Wahlqvist, Mark L; Lukito, Widjaja; Burke, Valerie; Ward, Natalie C; Prince, Richard L; Croft, Kevin D

    2004-02-01

    Tea and coffee are rich in polyphenols with a variety of biological activities. Many of the demonstrated activities are consistent with favourable effects on the risk of chronic diseases. 4-O-methylgallic acid (4OMGA) and isoferulic acid are potential biomarkers of exposure to polyphenols derived from tea and coffee respectively. 4OMGA is derived from gallic acid in tea, and isoferulic acid is derived from chlorogenic acid in coffee. Our major objective was to explore the relationships of tea and coffee intake with 24 h urinary excretion of 4OMGA and isoferulic acid in human subjects. The relationships of long-term usual (111 participants) and contemporaneously recorded current (344 participants) tea and coffee intake with 24 h urinary excretion of 4OMGA and isoferulic acid were assessed in two populations. 4OMGA was related to usual (r 0.50, P<0.001) and current (r 0.57, P<0.001) tea intake, and isoferulic acid was related to usual (r 0.26, P=0.008) and current (r 0.18, P<0.001) coffee intake. Overall, our present results are consistent with the proposal that 4OMGA is a good biomarker for black tea-derived polyphenol exposure, but isoferulic acid may be of limited usefulness as a biomarker for coffee-derived polyphenol exposure.

  13. Time course of systemic oxidative stress and inflammatory response induced by an acute exposure to Residual Oil Fly Ash

    SciTech Connect

    Marchini, T.; Magnani, N.D.; Paz, M.L.; Vanasco, V.; Tasat, D.; González Maglio, D.H.; and others

    2014-01-15

    It is suggested that systemic oxidative stress and inflammation play a central role in the onset and progression of cardiovascular diseases associated with the exposure to particulate matter (PM). The aim of this work was to evaluate the time changes of systemic markers of oxidative stress and inflammation, after an acute exposure to Residual Oil Fly Ash (ROFA). Female Swiss mice were intranasally instilled with a ROFA suspension (1.0 mg/kg body weight) or saline solution, and plasma levels of oxidative damage markers [thiobarbituric acid reactive substances (TBARSs) and protein carbonyls], antioxidant status [reduced (GSH) and oxidized (GSSG) glutathione, ascorbic acid levels, and superoxide dismutase (SOD) activity], cytokines levels, and intravascular leukocyte activation were evaluated after 1, 3 or 5 h of exposure. Oxidative damage to lipids and decreased GSH/GSSG ratio were observed in ROFA-exposed mice as early as 1 h. Afterwards, increased protein oxidation, decreased ascorbic acid content and SOD activity were found in this group at 3 h. The onset of an adaptive response was observed at 5 h after the ROFA exposure, as indicated by decreased TBARS plasma content and increased SOD activity. The observed increase in oxidative damage to plasma macromolecules, together with systemic antioxidants depletion, may be a consequence of a systemic inflammatory response triggered by the ROFA exposure, since increased TNF-α and IL-6 plasma levels and polymorphonuclear leukocytes activation was found at every evaluated time point. These findings contribute to the understanding of the increase in cardiovascular morbidity and mortality, in association with environmental PM inhalation. - Highlights: • An acute exposure to ROFA triggers the occurrence of systemic oxidative stress. • Changes in plasmatic oxidative stress markers appear as early as 1 h after exposure. • ROFA induces proinflammatory cytokines release and intravascular leukocyte activation. • PMN

  14. Optimal SNR exposure time for speckle imaging: experimental results with frequency-dependent detector noise

    NASA Astrophysics Data System (ADS)

    Tyler, David W.; Suzuki, Andrew H.; von Bokern, Mark A.; Keating, Donna D.; Roggemann, Michael C.

    1994-06-01

    We review recent arguments for using increased spectral bandwidth and exposure times to optimize the signal-to-noise ratio of speckle imaging estimators and discuss the tradeoff between camera exposure time and the number of data frames collected when observing time is fixed. We compare experimental results with a previously-derived expression for optimal exposure time and find reasonable agreement after accounting for frequency-dependent camera noise.

  15. PHARMACOKINETIC PROFILES OF PERFLUOROOCTANOIC ACID IN MICE AFTER CHRONIC EXPOSURE

    EPA Science Inventory

    Perfluorooctanoic acid (PFOA) is highly persistent in humans, with serum half-life estimates of 2.3 to 3.8 years. In the mouse, elimination of PFOA appears to be first-order after a single oral administration, with serum half-life estimates of 16 days for females and 22 days for ...

  16. ALTERED GENE EXPRESSION IN MOUSE LIVERS AFTER DICHLOROACETIC ACID EXPOSURE

    EPA Science Inventory

    Dichloroacetic acid (DCA) is a major by-product of water disinfection by chlorination. Several studies have demonstrated that DCA exhibits hepatocarcinogenic effects in rodents when administered in drinking water. The mechanism(s) involved in DCA induction of cancer are not clear...

  17. Persistence of DNA damage following exposure of human bladder cells to chronic monomethylarsonous acid

    SciTech Connect

    Wnek, S.M.; Medeiros, M.K.; Eblin, K.E.; Gandolfi, A.J.

    2009-12-01

    Malignant transformation was demonstrated in UROtsa cells following 52-weeks of exposure to 50 nM monomethylarsonous acid (MMA{sup III}); the result was the malignantly transformed cell line, URO-MSC. URO-MSC cells were used to study the induction of DNA damage and the alteration of DNA repair enzymes in both the presence of MMA{sup III} [URO-MSC(+)] and after subsequent removal of MMA{sup III} [URO-MSC(-)] following chronic, low-level exposure. In the presence of MMA{sup III}, URO-MSC(+) cells demonstrated a sustained increase in DNA damage following 12-weeks of exposure; in particular, a significant increase in DNA single-strand breaks at 12-weeks of exposure consistently elevated through 52 weeks. The persistence of DNA damage in URO-MSC cells was assessed after a 2-week removal of MMA{sup III}. URO-MSC(-) cells demonstrated a decrease in DNA damage compared to URO-MSC(+); however, DNA damage in URO-MSC(-) remained significantly elevated when compared to untreated UROtsa and increased in a time-dependent manner. Reactive oxygen species (ROS) were demonstrated to be a critical component in the generation of DNA damage determined through the incubation of ROS scavengers with URO-MSC cells. Poly (ADP-ribose) polymerase (PARP) is a key repair enzyme in DNA single-strand break repair. URO-MSC(+) resulted in a slight increase in PARP activity after 36-weeks of MMA{sup III} exposure, suggesting the presence of MMA{sup III} is inhibiting the increase in PARP activity. In support, PARP activity in URO-MSC(-) increased significantly, coinciding with a subsequent decrease in DNA damage demonstrated in URO-MSC(-) compared to URO-MSC(+). These data demonstrate that chronic, low-level exposure of UROtsa cells to 50 nM MMA{sup III} results in: the induction of DNA damage that remains elevated upon removal of MMA{sup III}; increased levels of ROS that play a role in MMA{sup III} induced-DNA damage; and decreased PARP activity in the presence of MMA{sup III}.

  18. Effects analysis of time-varying or repeated exposures in aquatic ecological risk assessment of agrochemicals.

    PubMed

    Reinert, Kevin H; Giddings, Jeffrey M; Judd, Laura

    2002-09-01

    Exposure to agrochemicals in the aquatic environment often occurs as time-varying or repeated pulses. Time-varying exposures may occur due to runoff events and spray drift associated with precipitation and application events. Hydrologic dilution, dispersion, and degradation also produce pulsed exposures. Standard laboratory toxicity tests using constant exposure concentrations typically do not investigate the toxicity of time-varying or repeated exposures. Detoxification, elimination, and recovery may occur within organisms or populations during the periods between exposures. The difficulty of estimating effects of realistic time-varying exposures from measurements made under constant exposure conditions is often an important source of uncertainty in ecological risk assessment of pesticides. This article discusses the criteria and tools for deciding whether time-varying exposures are relevant in a particular risk assessment, approaches for laboratory toxicity testing with time-varying exposure, modeling approaches for addressing effects oftime-varying exposure, deterministic and probabilistic ecological risk characterization of time-varyingexposures and toxicity, and uncertainty analysis.

  19. Time-space modeling of journey-time exposure to traffic-related air pollution using GIS.

    PubMed

    Gulliver, John; Briggs, David J

    2005-01-01

    Journey-time exposures represent an important, though as yet little-studied, component of human exposure to traffic-related air pollution, potentially with important health effects. Methods for assessing journey-time exposures, either as part of epidemiological studies or for policy assessment, are, however, poorly developed. This paper describes the development and testing of a GIS-based system for modeling human journey-time exposures to traffic-related air pollution: STEMS (Space-Time Exposure Modeling System). The model integrates data on source activity, pollutant dispersion, and travel behavior to derive individual- or group-level exposure measures to atmospheric pollution. The model, which is designed to simulate exposures of people as they move through a changing air pollution field, was developed, validated, and trialed in Northampton, UK. The system currently uses ArcInfo to couple four separate submodels: a source activity/emission model (SATURN), a proprietary atmospheric dispersion model (ADMS-Urban), an empirically derived background air pollution model, and a purposely designed time-activity-based exposure model (TOTEM). This paper describes the structure of the modeling system; presents results of field calibration, validation, and sensitivity analysis; and illustrates the use of the model to analyze journey-time exposures of schoolchildren.

  20. Retention of Idioms Following One-Time Exposure

    ERIC Educational Resources Information Center

    Reuterskiold, Christina; Van Lancker Sidtis, Diana

    2013-01-01

    This study explored retention of idioms and novel (i.e. newly created or grammatically generated) expressions in English-speaking girls following exposure only once during a conversation. Our hypothesis was that idioms, because of their inherent holistic, nonliteral and social characteristics, are acquired differently and more rapidly than novel…

  1. Making fate and exposure models for freshwater ecotoxicity in life cycle assessment suitable for organic acids and bases.

    PubMed

    van Zelm, Rosalie; Stam, Gea; Huijbregts, Mark A J; van de Meent, Dik

    2013-01-01

    Freshwater fate and exposure factors were determined for organic acids and bases, making use of the knowledge on electrical interaction of ionizing chemicals and their sorption to particles. The fate factor represents the residence time in the environment whereas exposure factors equal the dissolved fraction of a chemical. Multimedia fate, exposure, and effect model USES-LCA was updated to take into account the influence of ionization, based upon the acid dissociation constant (pK(a)) of a chemical, and the environmental pH. Freshwater fate (FF) and exposure (XF) factors were determined for 415 acids and 496 bases emitted to freshwater, air, and soil. The relevance of taking account of the degree of ionization of chemicals was tested by determining the ratio (R) of the new vs. fate and exposure factors determined with USES-LCA suitable for neutral chemicals only. Our results show that the majority of freshwater fate and exposure factors of chemicals that are largely ionized in the environment are larger with the ionics model compared to the factors determined with the neutrals model version. R(FF) ranged from 2.4×10(-1) to 1.6×10(1) for freshwater emissions, from 1.2×10(-2) to 2.0×10(4) for soil emissions and from 5.8×10(-2) to 6.0×10(3) for air emissions, and R(XF) from 5.3×10(-1) to 2.2×10(1). Prediction of changed solid-water partitioning, implying a change in runoff and in removal via sedimentation, and prediction of negligible air-water partition coefficient, leading to negligible volatilization were the main contributors to the changes in freshwater fate factors.

  2. CHRONIC EXPOSURE TO DIBROMOACETIC ACID, A WATER DISINFECTION BY-PRODUCT, DIMINISHES PRIMORDIAL FOLLICLES IN THE RABBIT

    EPA Science Inventory

    Exposure to dibromoacetic acid (DBA), a commonly occurring water disinfection by-product, has detrimental effects on spermatogenesis and fertility in rats and rabbits. Despite indications of important reproductive consequences of DBA exposure in males, reproductive sequelae follo...

  3. Acute acidic exposure induces p53-mediated oxidative stress and DNA damage in tilapia (Oreochromis niloticus) blood cells.

    PubMed

    Mai, Wei-jun; Yan, Jun-lun; Wang, Lei; Zheng, Ying; Xin, Yu; Wang, Wei-na

    2010-11-01

    Acid rain and inputs of acidic effluent can result in increased acidity in aquatic ecosystems, where it is known to have a significant impact and possibly, to cause the decline of some populations of aquatic organisms. In previous studies, intracellular acid-induced oxidative stress has been shown to cause DNA damage, and cooperatively activate the expression of the p53 gene. The acute effects of acidic environments on shrimp and fish have been widely studied. However, the molecular mechanism of acid-induced injury remains largely unknown. In this study, we examined the cellular responses of tilapia to acidic exposure-induced oxidative stress and antioxidant enzyme gene expression. Furthermore, we determined how acute acid stress activates the ATM-p53 signal pathway. We measured the upregulation of reactive oxygen species (ROS) production, the intracellular Ca(2)(+) concentration ([Ca(2)(+)](i)), the tail DNA values, the malondialdehyde (MDA) level in the blood cells and the percentage of dead and damaged blood cells. Our results suggest that oxidative stress and DNA damage occurred in tilapia in conditions where the pH was 5.3. Apoptosis was detected by Hoechst staining, which was mainly associated with changes in cell viability. The parameters that we measured were related to acid-induced DNA damage, and all parameters changed in the blood cells through time. The effects of acute acid exposure (pH 5.3) on the expression of ATM, p53, p21, Bax, manganese superoxide dismutase (MnSOD), glutathione peroxidase (GPx) were investigated in tilapia blood cells. The results showed that acute acid stress induced upregulation of ATM, p53 and p21, associated with increasing of DNA damage and apoptosis in blood cells. Additionally, the expression of Bax was slightly increased. Moreover, consensus p53-binding sequences were identified in tilapia MnSOD and GPx gene promoter regions and increased levels of ROS in the blood cells coincided with increased mRNA expression of p53, Mn

  4. Evaluation of the toxicity data for peracetic acid in deriving occupational exposure limits: a minireview.

    PubMed

    Pechacek, Nathan; Osorio, Magdalena; Caudill, Jeff; Peterson, Bridget

    2015-02-17

    Peracetic acid (PAA) is a peroxide-based chemistry that is highly reactive and can produce strong local effects upon direct contact with the eyes, skin and respiratory tract. Given its increasing prominence in industry, attention has focused on health hazards and associated risks for PAA in the workplace. Occupational exposure limits (OEL) are one means to mitigate risks associated with chemical hazards in the workplace. A mini-review of the toxicity data for PAA was conducted in order to determine if the data were sufficient to derive health-based OELs. The available data for PAA frequently come from unpublished studies that lack sufficient study details, suffer from gaps in available information and often follow unconventional testing methodology. Despite these limitations, animal and human data suggest sensory irritation as the most sensitive endpoint associated with inhalation of PAA. Rodent RD50 data (the concentration estimated to cause a 50% depression in respiratory rate) were selected as the critical studies in deriving OELs. Based on these data, a range of 0.36-0.51mg/m(3) (0.1-0.2ppm) was calculated for a time-weighted average (TWA), and 1.2-1.7mg/m(3) (0.4-0.5ppm) as a range for a short-term exposure limit (STEL). These ranges compare favorably to other published OELs for PAA. Considering the applicable health hazards for this chemistry, a joint TWA/STEL OEL approach for PAA is deemed the most appropriate in assessing workplace exposures to PAA, and the selection of specific values within these proposed ranges represents a risk management decision. PMID:25542141

  5. Effect of acute nitrogen dioxide exposure on the composition of fatty acid associated with phospholipids in alveolar lavage

    SciTech Connect

    Kobayashi, T.; Noguchi, T.; Kikuno, M.; Kubota, K.

    1984-01-01

    In vivo exposure of rats to 10 ppm nitrogen dioxide (NO/sub 2/) for 12 h caused changes in fatty acids composition of alveolar lavage phospholipids. Among the fatty acid species, the relative ratio of palmitic acid, myristic acid and palmitoleic acid increased significantly. While the relative ratio of stearic acid, oleic acid, linoleic acid and arachidonic acid decreased significantly. Both the increase in the incorporation of palmitic acid in phosphatidylcholine which would be released into the alveoli and the increase in the release of phosphatidylcholine into the alveoli may account for the changes in the fatty acid composition of the present findings.

  6. [Development of breathing chest radiography: study of exposure timing].

    PubMed

    Tanaka, Rie; Sanada, Shigeru; Kobayashi, Takeshi; Suzuki, Masayuki; Matsui, Takeshi; Inoue, Hitoshi

    2003-08-01

    The flat-panel detector (FPD) has been introduced into clinical practice. A modified FPD, which has the ability to obtain dynamic chest radiographs, was introduced into our hospital, and clinical testing is ongoing. Both the inspiratory and expiratory phases have to be included in dynamic chest radiographs. The purpose of this study was to investigate the most appropriate chest radiography signal for observation of the respiratory process. We prepared ten protocol patterns that differed in terms of respiratory phase at X-ray exposure, exposure duration, and signal multiplicity. We also performed preliminary experiments and administered several questionnaires to ten volunteers. The volunteers breathed according to vocal and visual signals, and their respiratory waves were recorded by spirometer. The most appropriate protocol was similar to the method used for conventional chest radiography. PMID:12960952

  7. Perinatal exposure to endocrine disruptors: sex, timing and behavioral endpoints

    PubMed Central

    Palanza, Paola; Nagel, Susan C; Parmigiani, Stefano; vom Saal, Frederick S

    2016-01-01

    Of the approximately 85,000 chemicals in use, 1000 have been identified as having the ability to disrupt normal endocrine function. Exposure to endocrine disrupting chemicals (EDCs) during critical period in brain differentiation (prenatal and neonatal life) via the mother can alter the course of the development of sexually dimorphic behaviors. Bisphenol A (BPA) is a very high volume chemical used in plastic, resins and other products, and virtually everyone examined has detectable BPA. BPA has estrogenic activity and is one of the most studied EDCs. We review evidence from studies in rodents using dose levels relevant to human exposure. BPA alters behavior and eliminates or in some cases reverses sexually dimorphic behaviors observed in unexposed animals. PMID:27019862

  8. Near-Real-Time Analysis of the Phenotypic Responses of Escherichia coli to 1-Butanol Exposure Using Raman Spectroscopy

    PubMed Central

    Zu, Theresah N. K.; Athamneh, Ahmad I. M.; Wallace, Robert S.; Collakova, Eva

    2014-01-01

    Raman spectroscopy was used to study the time course of phenotypic responses of Escherichia coli (DH5α) to 1-butanol exposure (1.2% [vol/vol]). Raman spectroscopy is of interest for bacterial phenotyping because it can be performed (i) in near real time, (ii) with minimal sample preparation (label-free), and (iii) with minimal spectral interference from water. Traditional off-line analytical methodologies were applied to both 1-butanol-treated and control cells to draw correlations with Raman data. Here, distinct sets of Raman bands are presented that characterize phenotypic traits of E. coli with maximized correlation to off-line measurements. In addition, the observed time course phenotypic responses of E. coli to 1.2% (vol/vol) 1-butanol exposure included the following: (i) decreased saturated fatty acids levels, (ii) retention of unsaturated fatty acids and low levels of cyclopropane fatty acids, (iii) increased membrane fluidity following the initial response of increased rigidity, and (iv) no changes in total protein content or protein-derived amino acid composition. For most phenotypic traits, correlation coefficients between Raman spectroscopy and traditional off-line analytical approaches exceeded 0.75, and major trends were captured. The results suggest that near-real-time Raman spectroscopy is suitable for approximating metabolic and physiological phenotyping of bacterial cells subjected to toxic environmental conditions. PMID:25157078

  9. EXPOSURE DOMAINS: ROLE OF TIMING, PATTERN AND MAGNITUDE OF EXPOSURE ON HEALTH RISKS

    EPA Science Inventory

    Environmental health risk assessment may be broadly separated into assessment of risks from exposures to agents affecting health endpoints for which it may be presumed there is no dose threshold, and to agents affecting endpoints that more likely have a dose threshold. For hea...

  10. Effects of acid exposure on the conformation, stability, and aggregation of monoclonal antibodies.

    PubMed

    Ejima, Daisuke; Tsumoto, Kouhei; Fukada, Harumi; Yumioka, Ryosuke; Nagase, Kazuo; Arakawa, Tsutomu; Philo, John S

    2007-03-01

    Exposure of antibodies to low pH is often unavoidable for purification and viral clearance. The conformation and stability of two humanized monoclonal antibodies (hIgG4-A and -B) directed against different antigens and a mouse monoclonal antibody (mIgG1) in 0.1M citrate at acidic pH were studied using circular dichroism (CD), differential scanning calorimetry (DSC), and sedimentation velocity. Near- and far-UV CD spectra showed that exposure of these antibodies to pH 2.7-3.9 induced only limited conformational changes, although the changes were greater at the lower pH. However, the acid conformation is far from unfolded or so-called molten globule structure. Incubation of hIgG4-A at pH 2.7 and 3.5 at 4 degrees C over the course of 24 h caused little change in the near-UV CD spectra, indicating that the acid conformation is stable. Sedimentation velocity showed that the hIgG4-A is largely monomeric at pH 2.7 and 3.5 as well as at pH 6.0. No time-dependent changes in sedimentation profile occurred upon incubation at these low pHs, consistent with the conformational stability observed by CD. The sedimentation coefficient of the monomer at pH 2.7 or 3.5 again suggested that no gross conformational changes occur at these pHs. DSC analysis of the antibodies showed thermal unfolding at pH 2.7-3.9 as well as at pH 6.0, but with decreased melting temperatures at the lower pH. These results are consistent with the view that the antibodies undergo limited conformational change, and that incubation at 4 degrees C at low pH results in no time-dependent conformational changes. Titration of hIgG4-A from pH 3.5 to 6.0 resulted in recovery of native monomeric proteins whose CD and DSC profiles resembled those of the original sample. However, titration from pH 2.7 resulted in lower recovery of monomeric antibody, indicating that the greater conformational changes observed at this pH cannot be fully reversed to the native structure by a simple pH titration.

  11. Exposure time-dependent thermal effects of radiofrequency electromagnetic field exposure on the whole body of rats.

    PubMed

    Ohtani, Shin; Ushiyama, Akira; Maeda, Machiko; Hattori, Kenji; Kunugita, Naoki; Wang, Jianqing; Ishii, Kazuyuki

    2016-01-01

    We investigated the thermal effects of radiofrequency electromagnetic fields (RF-EMFs) on the variation in core temperature and gene expression of some stress markers in rats. Sprague-Dawley rats were exposed to 2.14 GHz wideband code division multiple access (W-CDMA) RF signals at a whole-body averaged specific absorption rate (WBA-SAR) of 4 W/kg, which causes behavioral disruption in laboratory animals, and 0.4 W/kg, which is the limit for the occupational exposure set by the International Commission on Non-Ionizing Radiation Protection guideline. It is important to understand the possible in vivo effects derived from RF-EMF exposures at these intensities. Because of inadequate data on real-time core temperature analyses using free-moving animal and the association between stress and thermal effects of RF-EMF exposure, we analyzed the core body temperature under nonanesthetic condition during RF-EMF exposure. The results revealed that the core temperature increased by approximately 1.5°C compared with the baseline and reached a plateau till the end of RF-EMF exposure. Furthermore, we analyzed the gene expression of heat-shock proteins (Hsp) and heat-shock transcription factors (Hsf) family after RF-EMF exposure. At WBA-SAR of 4 W/kg, some Hsp and Hsf gene expression levels were significantly upregulated in the cerebral cortex and cerebellum following exposure for 6 hr/day but were not upregulated after exposure for 3 hr/day. On the other hand, there was no significant change in the core temperature and gene expression at WBA-SAR of 0.4 W/kg. Thus, 2.14-GHz RF-EMF exposure at WBA-SAR of 4 W/kg induced increases in the core temperature and upregulation of some stress markers, particularly in the cerebellum. PMID:27665775

  12. Exposure time-dependent thermal effects of radiofrequency electromagnetic field exposure on the whole body of rats.

    PubMed

    Ohtani, Shin; Ushiyama, Akira; Maeda, Machiko; Hattori, Kenji; Kunugita, Naoki; Wang, Jianqing; Ishii, Kazuyuki

    2016-01-01

    We investigated the thermal effects of radiofrequency electromagnetic fields (RF-EMFs) on the variation in core temperature and gene expression of some stress markers in rats. Sprague-Dawley rats were exposed to 2.14 GHz wideband code division multiple access (W-CDMA) RF signals at a whole-body averaged specific absorption rate (WBA-SAR) of 4 W/kg, which causes behavioral disruption in laboratory animals, and 0.4 W/kg, which is the limit for the occupational exposure set by the International Commission on Non-Ionizing Radiation Protection guideline. It is important to understand the possible in vivo effects derived from RF-EMF exposures at these intensities. Because of inadequate data on real-time core temperature analyses using free-moving animal and the association between stress and thermal effects of RF-EMF exposure, we analyzed the core body temperature under nonanesthetic condition during RF-EMF exposure. The results revealed that the core temperature increased by approximately 1.5°C compared with the baseline and reached a plateau till the end of RF-EMF exposure. Furthermore, we analyzed the gene expression of heat-shock proteins (Hsp) and heat-shock transcription factors (Hsf) family after RF-EMF exposure. At WBA-SAR of 4 W/kg, some Hsp and Hsf gene expression levels were significantly upregulated in the cerebral cortex and cerebellum following exposure for 6 hr/day but were not upregulated after exposure for 3 hr/day. On the other hand, there was no significant change in the core temperature and gene expression at WBA-SAR of 0.4 W/kg. Thus, 2.14-GHz RF-EMF exposure at WBA-SAR of 4 W/kg induced increases in the core temperature and upregulation of some stress markers, particularly in the cerebellum.

  13. Dietary exposure estimates for the food preservatives benzoic acid and sorbic acid in the total diet in Taiwan.

    PubMed

    Ling, Min-Pei; Lien, Keng-Wen; Wu, Chiu-Hua; Ni, Shih-Pei; Huang, Hui-Ying; Hsieh, Dennis P H

    2015-02-25

    The purpose was to assess the health risk to general consumers in Taiwan associated with dietary intake of benzoic acid and sorbic acid by conducting a total diet study (TDS). The hazard index (HI) in percent acceptable daily intake (%ADI) of benzoic acid and sorbic acid for eight exposure groups classified by age were calculated. In high-intake consumers, the highest HI of benzoic acid was 54.1%ADI for males aged 1-2 years old at the 95th percentile, whereas for females, the HI was 61.7%ADI for aged over 66 years old. The highest HI of sorbic acid for male and female consumers aged 3-6 years old at the 95th percentile were 14.0%ADI and 12.2%ADI, respectively. These results indicate that the use of benzoic acid and sorbic acid as preservatives at the current level of use in the Taiwanese diet does not constitute a public health and safety concern.

  14. Ascorbic Acid Ameliorates Nicotine Exposure Induced Impaired Spatial Memory Performance in Rats

    PubMed Central

    Sirasanagandla, SR; Rooben, RK; Rajkumar; Narayanan, SN; Jetti, R

    2014-01-01

    Introduction: The long lasting behavioural and cognitive impairments in offspring prenatally exposed to nicotine have been confirmed in animal models. In the present study, we investigated the effect of ascorbic acid on prenatal nicotine exposure induced behavioural deficits in male offspring of rats. Methods: The pregnant Wistar dams were divided into four groups of six rats: control, vehicle control, nicotine and nicotine+ascorbic acid groups. The nicotine group received daily dose of subcutaneous injections of 0.96 mg/kg body weight (bw) nicotine free base throughout gestation. Pregnant dams in nicotine+ascorbic acid group were first given nicotine free base (0.96 mg/kg bw/day; subcutaneous route) followed by ascorbic acid (50 mg/kg bw/day, orally) daily throughout gestation. The cognitive function of male offspring of all the experimental groups was studied using Morris water maze test at postnatal day 40. Results: Prenatal nicotine exposure altered spatial learning and memory in male offspring. However, treatment with ascorbic acid ameliorated these changes in rats. Conclusion: Ascorbic acid supplementation was found to be effective in preventing the prenatal nicotine exposure induced cognitive deficits in rat offspring to some extent. PMID:25429474

  15. A new real time filter for local exposure correction in panoramic radiographs

    SciTech Connect

    Frosio, I.; Borghese, N. A.

    2006-09-15

    A new real time filter for local exposure correction in panoramic radiographs is presented here. The filter, called PaRSEC, allows eliminating the exposure artifacts, mainly introduced by Automatic Exposure Control (AEC) systems. These artifacts reduce the image readability and its diagnostic utility. The PaRSEC filter operates a local exposure equalization, based on a reliable estimate of the column mean gray level. Qualitative and quantitative results are reported for typical panoramic radiographs. They show a complete removal of the artifacts. The method compares favorably with other classical methods targeted to exposure correction.

  16. The Timing of Exposure in Clinic-Based Treatment for Childhood Anxiety Disorders

    ERIC Educational Resources Information Center

    Gryczkowski, Michelle R.; Tiede, Michael S.; Dammann, Julie E.; Jacobsen, Amy Brown; Hale, Lisa R.; Whiteside, Stephen P. H.

    2013-01-01

    The present study examines treatment length and timing of exposure from two child anxiety disorders clinics. Data regarding symptoms and treatment characteristics for 28 youth were prospectively obtained through self, parent, and therapist report at each session. Information regarding length of treatment, timing of exposure initiation, and…

  17. Neurobehavioral effects of exposure to propionic acid revisited-Does psychosocial stress interfere with distractive effects in volunteers?

    PubMed

    Pacharra, Marlene; Schäper, Michael; Kleinbeck, Stefan; Blaszkewicz, Meinolf; Golka, Klaus; van Thriel, Christoph

    2016-07-01

    Local irritants stimulate the nervous system via chemosensory pathways that trigger cognitive distraction, subjective complaints about impaired health, and physiological defense reflexes (e.g. eye-blinks). At workplaces and in the environment chemical exposures often co-occur with psychosocial stress. This study investigated if stress modulates adverse effects of exposure to the local irritant and malodorant propionic acid (PA). Forty-eight participants were randomly assigned to an experimental (false negative feedback+salient surveillance) or control group. In a cross-over design, both groups were exposed for 4h to PA in concentrations of 0.3 and 0-20ppm (time-weighted average=10ppm). In the experimental group, the stress protocol induced moderate psychosocial stress as indicated by salivary cortisol and subjective responses. Despite concentration-dependent increases in chemosensory perceptions and symptoms, the level of exposure to PA had no impact upon the results of four out of six neurobehavioral tests. In the sustained attention test, there was a significant increase in error rates that corresponded to the exposure levels. However, a concentration-dependent impairment of spatial working memory and an adverse increase in eye-blink frequency were restricted to the control group. Stressed participants had shorter simple reaction times and high eye-blink frequency irrespective of exposure suggesting enhanced alertness. Psychosocial stress increased complaints, ocular irritation and unspecific symptoms at the end of the 0.3ppm exposure to a level that was comparable with that in the control group during exposure to 0-20ppm. Results indicate that the adverse effects of a local irritant and psychosocial stress are non-additive.

  18. Time course of systemic oxidative stress and inflammatory response induced by an acute exposure to Residual Oil Fly Ash.

    PubMed

    Marchini, T; Magnani, N D; Paz, M L; Vanasco, V; Tasat, D; González Maglio, D H; Alvarez, S; Evelson, P A

    2014-01-15

    It is suggested that systemic oxidative stress and inflammation play a central role in the onset and progression of cardiovascular diseases associated with the exposure to particulate matter (PM). The aim of this work was to evaluate the time changes of systemic markers of oxidative stress and inflammation, after an acute exposure to Residual Oil Fly Ash (ROFA). Female Swiss mice were intranasally instilled with a ROFA suspension (1.0mg/kg body weight) or saline solution, and plasma levels of oxidative damage markers [thiobarbituric acid reactive substances (TBARSs) and protein carbonyls], antioxidant status [reduced (GSH) and oxidized (GSSG) glutathione, ascorbic acid levels, and superoxide dismutase (SOD) activity], cytokines levels, and intravascular leukocyte activation were evaluated after 1, 3 or 5h of exposure. Oxidative damage to lipids and decreased GSH/GSSG ratio were observed in ROFA-exposed mice as early as 1h. Afterwards, increased protein oxidation, decreased ascorbic acid content and SOD activity were found in this group at 3h. The onset of an adaptive response was observed at 5h after the ROFA exposure, as indicated by decreased TBARS plasma content and increased SOD activity. The observed increase in oxidative damage to plasma macromolecules, together with systemic antioxidants depletion, may be a consequence of a systemic inflammatory response triggered by the ROFA exposure, since increased TNF-α and IL-6 plasma levels and polymorphonuclear leukocytes activation was found at every evaluated time point. These findings contribute to the understanding of the increase in cardiovascular morbidity and mortality, in association with environmental PM inhalation. PMID:24321338

  19. Time course of systemic oxidative stress and inflammatory response induced by an acute exposure to Residual Oil Fly Ash.

    PubMed

    Marchini, T; Magnani, N D; Paz, M L; Vanasco, V; Tasat, D; González Maglio, D H; Alvarez, S; Evelson, P A

    2014-01-15

    It is suggested that systemic oxidative stress and inflammation play a central role in the onset and progression of cardiovascular diseases associated with the exposure to particulate matter (PM). The aim of this work was to evaluate the time changes of systemic markers of oxidative stress and inflammation, after an acute exposure to Residual Oil Fly Ash (ROFA). Female Swiss mice were intranasally instilled with a ROFA suspension (1.0mg/kg body weight) or saline solution, and plasma levels of oxidative damage markers [thiobarbituric acid reactive substances (TBARSs) and protein carbonyls], antioxidant status [reduced (GSH) and oxidized (GSSG) glutathione, ascorbic acid levels, and superoxide dismutase (SOD) activity], cytokines levels, and intravascular leukocyte activation were evaluated after 1, 3 or 5h of exposure. Oxidative damage to lipids and decreased GSH/GSSG ratio were observed in ROFA-exposed mice as early as 1h. Afterwards, increased protein oxidation, decreased ascorbic acid content and SOD activity were found in this group at 3h. The onset of an adaptive response was observed at 5h after the ROFA exposure, as indicated by decreased TBARS plasma content and increased SOD activity. The observed increase in oxidative damage to plasma macromolecules, together with systemic antioxidants depletion, may be a consequence of a systemic inflammatory response triggered by the ROFA exposure, since increased TNF-α and IL-6 plasma levels and polymorphonuclear leukocytes activation was found at every evaluated time point. These findings contribute to the understanding of the increase in cardiovascular morbidity and mortality, in association with environmental PM inhalation.

  20. Evaluation of biomarkers of environmental exposures: urinary haloacetic acids associated with ingestion of chlorinated drinking water.

    PubMed

    Kim, H; Haltmeier, P; Klotz, J B; Weisel, C P

    1999-02-01

    A study was conducted to determine if DCAA and TCAA urinary excretion rates are valid biomarkers of chronic ingestion exposure to these disinfection by-products of chlorination of drinking water. Entire first morning urine voids, time-of-visit urine samples, and tap water samples were collected from 47 female subjects. In addition, a 48-h recall questionnaire was administered to determine the amounts and types of liquids ingested by each subject as well as other exposures that could lead to DCAA and TCAA urinary excretion. The TCAA excretion rate for the first morning urine samples was significantly correlated with the estimated 48-h TCAA ingestion exposure for 25 subjects whose ingestion exposures primarily occurred at home, while the DCAA excretion rate was not correlated with the DCAA ingestion exposure. Thus, urinary TCAA appears to be a valid biomarker of chronic ingestion exposure to TCAA from chlorinated water, while urinary DCAA is not. It is proposed that the difference in the biological half-lives between these two compounds is the rationale for this finding. The biological half-life of TCAA is longer than successive exposure intervals; thus TCAA accumulates until it reaches a steady state. The half-life of DCAA is shorter than successive exposure intervals; thus DCAA is almost completely metabolized following an exposure and is eliminated from the body. This study suggests that biological half-life, exposure interval, and sample collection interval should be considered in selecting biomarkers and designing studies to validate them.

  1. Effects of ozone and acid aerosol exposures on surfactant-associated protein A in the lung

    SciTech Connect

    Su, W.Y.

    1993-01-01

    This study examined the effect of ozone and/or acid aerosol exposure on the level of surfactant associated protein A (SP-A), its gene expression and functionality in the lung. Guinea pigs were exposed to (1) a single exposure to 0.2 to 0.8 ppm ozone for 6 hr and sacrificed at 0 to 120 hr postexposure, (2) 0.8 ppm ozone, 6 hr/day for 3 to 5 days and sacrificed immediately postexposure, or (3) 0.8 ppm ozone, 600 [mu]g/m[sup 3] sulfuric acid, or ozone plus acid for 6 hr and sacrificed at 72 hr postexposure. The concentration of SP-A was determined by ELISA in lavage fluid, lavage cell pellets, and lung tissue compartments. SP-A gene expression was examined in lung tissue by Northern and slot blot analysis. Effect of ozone exposure on functionality of surfactant was tested by its ability to modulate phagocytic cell respiratory burst in a luminol-amplified chemiluminescence (CL) assay of phagocytic cells simulated by PMA or opsonized-zymosan. There were isolated, but significant, changes in SP-A concentrations in the lavage cell and the lavage fluid compartments at 24 and 48 hr after single exposure to 0.8 ppm ozone, respectively. Exposure to ozone and ozone plus acid also slightly increased total SP-A level in the lung. No change in SP-A gene expression was detected under the exposure conditions examined. However, surfactant from ozone exposed animals significantly enhanced CL response of phagocytic cells stimulated by either PMA or opsonized-zymosan. Blocking of the enhancement of CL by a rabbit anti-human SP-A antibody strongly suggested that SP-A may contribute in the altered respiratory burst of phagocytic cells induced by surfactant from ozone exposed animals.

  2. Further investigations on the role of ascorbic acid in stratum corneum lipid models after UV exposure.

    PubMed

    Trommer, Hagen; Böttcher, Rolf; Huschka, Christoph; Wohlrab, Wolfgang; Neubert, Reinhard H H

    2005-08-01

    This study is the continuation of our research into vitamin C and its possible effects on human skin after topical administration. The effects of ascorbic acid, iron ions and UV irradiation on stratum corneum lipid models were investigated. The lipid models used were: a simple system (linolenic acid dispersion), a complex system (liposomes consisting of dipalmitoylphosphatidylcholine, cholesterol and linolenic acid) and complex systems with additionally incorporated ceramides (types III and IV). The lipid peroxidation was quantified by the thiobarbituric acid assay. A human adult low-calcium high-temperature (HaCaT) keratinocytes cell culture was used as a second in-vitro model. The amount of intracellular peroxides was determined by measuring the fluorescence intensity using the dihydrorhodamine 123 assay. Electron paramagnetic resonance spectroscopy was used to study the influence of ascorbic acid and iron ions on the signal intensity of 5-doxylstearic acid during UV exposure. Ascorbic acid showed prooxidative properties in the thiobarbituric acid assay whereas cell protection was measured in the HaCaT keratinocytes experiments. Electron paramagnetic resonance investigations revealed different extents of free radical production generated by iron ions, ascorbic acid and UV irradiation. In evaluating the results from this study new aspects of the mechanism of lipid damage caused by these three factors were suggested, transcending the simple redox behaviour of ascorbic acid. PMID:16102251

  3. Acute effects of chlorinated resin acid exposure on juvenile rainbow trout, Oncorhynchus mykiss

    SciTech Connect

    Kennedy, C.J.; Sweeting, R.M.; Farrell, A.P.; McKeown, B.A.; Johansen, J.A.

    1995-06-01

    The effects of an acute exposure to either 14-monochlorodehydroabietic acid (MCDHAA) or 12,14-dichlorodehydroabietic acid (DCDHAA) were examined in juvenile rainbow trout, Oncorhynchus mykiss. The experimentally determined 96-h LC50 values (and their 95% confidence limits) were 1.03 (0.72, 1.48) and 0.91 (0.70, 1.21) mg/L, for MCDHAA and DCDHAA, respectively. To measure effects on several biochemical parameters, swimming performance, and disease resistance, juvenile trout were exposed for 24 h to sublethal concentrations of one or the other resin acid in an intermittent-flow respirometer. Hematocrit, plasma lactate, and liver protein were significantly affected by exposure to the highest dose (80% of the 96-h LC50 value) of either of the resin acids. Plasma cortisol levels were 14- and 3-fold higher than were controls. Resistance to infection by Aeromonas salmonicida was significantly reduced; the cumulative percent mortalities due to furunculosis in fish exposed to MCDHAA or DCDHAA reached 20 and 26%, respectively. Swimming performance, measured as critical swimming speed (mean values 6.32 {+-} 0.20 and 5.93 {+-} 0.15 body lengths per second for MCDHAA and DCDHAA, respectively), was not significantly affected by resin acid exposure.

  4. Effect of Exposure Time and Organic Matter on Efficacy of Antimicrobial Compounds against Shiga Toxin-Producing Escherichia coli and Salmonella.

    PubMed

    Kalchayanand, Norasak; Koohmaraie, Mohammad; Wheeler, Tommy L

    2016-04-01

    Several antimicrobial compounds are in commercial meat processing plants for pathogen control on beef carcasses. However, the efficacy of the method used is influenced by a number of factors, such as spray pressure, temperature, type of chemical and concentration, exposure time, method of application, equipment design, and the stage in the process that the method is applied. The objective of this study was to evaluate effectiveness of time of exposure of various antimicrobial compounds against nine strains of Shiga toxin-producing Escherichia coli (STEC) and four strains of Salmonella in aqueous antimicrobial solutions with and without organic matter. Non-O157 STEC, STEC O157:H7, and Salmonella were exposed to the following aqueous antimicrobial solutions with or without beef purge for 15, 30, 60, 120, 300, 600, and 1,800 s: (i) 2.5% lactic acid, (ii) 4.0% lactic acid, (iii) 2.5% Beefxide, (iv) 1% Aftec 3000, (v) 200 ppm of peracetic acid, (vi) 300 ppm of hypobromous acid, and (vii) water as a control. In general, increasing exposure time to antimicrobial compounds significantly (P ≤ 0.05) increased the effectiveness against pathogens tested. In aqueous antimicrobial solutions without organic matter, both peracetic acid and hypobromous acid were the most effective in inactivating populations of STEC and Salmonella, providing at least 5.0-log reductions with exposure for 15 s. However, in antimicrobials containing organic matter, 4.0% lactic acid was the most effective compound in reducing levels of STEC and Salmonella, providing 2- to 3-log reductions with exposure for 15 s. The results of this study indicated that organic matter and exposure time influenced the efficacy of antimicrobial compounds against pathogens, especially with oxidizer compounds. These factors should be considered when choosing an antimicrobial compound for an intervention. PMID:27052859

  5. Effect of Exposure Time and Organic Matter on Efficacy of Antimicrobial Compounds against Shiga Toxin-Producing Escherichia coli and Salmonella.

    PubMed

    Kalchayanand, Norasak; Koohmaraie, Mohammad; Wheeler, Tommy L

    2016-04-01

    Several antimicrobial compounds are in commercial meat processing plants for pathogen control on beef carcasses. However, the efficacy of the method used is influenced by a number of factors, such as spray pressure, temperature, type of chemical and concentration, exposure time, method of application, equipment design, and the stage in the process that the method is applied. The objective of this study was to evaluate effectiveness of time of exposure of various antimicrobial compounds against nine strains of Shiga toxin-producing Escherichia coli (STEC) and four strains of Salmonella in aqueous antimicrobial solutions with and without organic matter. Non-O157 STEC, STEC O157:H7, and Salmonella were exposed to the following aqueous antimicrobial solutions with or without beef purge for 15, 30, 60, 120, 300, 600, and 1,800 s: (i) 2.5% lactic acid, (ii) 4.0% lactic acid, (iii) 2.5% Beefxide, (iv) 1% Aftec 3000, (v) 200 ppm of peracetic acid, (vi) 300 ppm of hypobromous acid, and (vii) water as a control. In general, increasing exposure time to antimicrobial compounds significantly (P ≤ 0.05) increased the effectiveness against pathogens tested. In aqueous antimicrobial solutions without organic matter, both peracetic acid and hypobromous acid were the most effective in inactivating populations of STEC and Salmonella, providing at least 5.0-log reductions with exposure for 15 s. However, in antimicrobials containing organic matter, 4.0% lactic acid was the most effective compound in reducing levels of STEC and Salmonella, providing 2- to 3-log reductions with exposure for 15 s. The results of this study indicated that organic matter and exposure time influenced the efficacy of antimicrobial compounds against pathogens, especially with oxidizer compounds. These factors should be considered when choosing an antimicrobial compound for an intervention.

  6. A methodology for estimating human exposure to perfluorooctanoic acid (PFOA): a retrospective exposure assessment of a community (1951-2003).

    PubMed

    Paustenbach, Dennis J; Panko, Julie M; Scott, Paul K; Unice, Kenneth M

    2007-01-01

    Perfluorooctanoic acid (PFOA) is a persistent chemical that was recently shown to be widely distributed in the ambient environment. Because of concerns about the possible adverse health effects on persons exposed to PFOA, a retrospective exposure assessment was conducted for a population of about 50,000 persons who reside near one of the facilities where this chemical was used. No similar study of any chemical with the properties of PFOA had ever been performed; thus, several novel methods were developed and applied in this analysis. Historical records of the emissions from the facility were the basis for the estimates of the potential intake of (PFOA) by residents over the past 53 yr. Various well-accepted environmental models were dynamically combined in order to estimate the concentrations in all relevant environmental media including ambient air, surface soil, drinking water, and homegrown vegetables. Following considerable analyses, particulate deposition from facility air emissions to soil and the subsequent transfer of the chemical through the soil was determined to be the most likely source of PFOA that was detected in groundwater. The highest off-site environmental concentrations were predicted to occur about 1 mile away. For this approximately square mile area, during the time period 1951-2003, the model-estimated average air concentration was 0.2 microg/m3, the estimated surface soil concentration was 11 microg/kg, and the estimated drinking water concentration was 4 microg/L. Similar data were generated for 20 additional geographical areas around the facility. Comparison of measured PFOA concentrations in groundwater in the various water districts indicated that the models appeared to overpredict recent groundwater concentrations by a factor of 3 to 5. The predicted historical lifetime and average daily estimates of PFOA intake by persons who lived within 5 miles of the plant over the past 50 yr were about 10,000-fold less than the intake of the

  7. Evaluation of a chlorous acid-chlorine dioxide teat dip under experimental and natural exposure conditions.

    PubMed

    Drechsler, P A; Wildman, E E; Pankey, J W

    1990-08-01

    A postmilking teat dip containing chlorous acid-chlorine dioxide was evaluated by experimental challenge and in two herds under natural exposure. The test product had an efficacy of 78.9% against Staphylococcus aureus and 52.5% against Streptococcus agalactiae in the experimental challenge trial. The product was compared with a 1% iodine product in a 15-mo natural exposure study. Post-dipping with chlorous acid-chlorine dioxide reduced incidence of udder infection by major mastitis pathogens 36.1% when data were combined from the two herds. The 1% iodine and the chlorous acid-chlorine dioxide products were not equivalent for major mastitis pathogens; the test product was more effective. Incidence of udder infection by environmental mastitis pathogens was reduced 36.8% in both herds combined. Efficacy of the two teat dips was equivalent for environmental pathogens. PMID:2229601

  8. Duration and Timing of Exposure to Neighborhood Poverty and the Risk of Adolescent Parenthood

    PubMed Central

    Wodtke, Geoffrey T.

    2013-01-01

    Theory suggests that the impact of neighborhood poverty depends on both the duration and timing of exposure. Previous research, however, does not properly analyze the sequence of neighborhoods to which children are exposed throughout the early life course. This study investigates the effects of different longitudinal patterns of exposure to disadvantaged neighborhoods on the risk of adolescent parenthood. It follows a cohort of children in the PSID from age 4 to 19 and uses novel methods for time-varying exposures that overcome critical limitations of conventional regression when selection processes are dynamic. Results indicate that sustained exposure to poor neighborhoods substantially increases the risk of becoming a teen parent and that exposure to neighborhood poverty during adolescence may be more consequential than exposure earlier during childhood. PMID:23720166

  9. Impact of time-activity patterns on personal exposure to black carbon

    NASA Astrophysics Data System (ADS)

    Dons, Evi; Int Panis, Luc; Van Poppel, Martine; Theunis, Jan; Willems, Hanny; Torfs, Rudi; Wets, Geert

    2011-07-01

    Time-activity patterns are an important determinant of personal exposure to air pollution. This is demonstrated by measuring personal exposure of 16 participants for 7 consecutive days: 8 couples of which one person was a full-time worker and the other was a homemaker; both had a very different time-activity pattern. We used portable aethalometers to measure black carbon levels with a high temporal resolution and a PDA with GPS-logger and electronic diary. The exposure to black carbon differs between partners by up to 30%, although they live at the same location. The activity contributing most to this difference is transport: Average exposure in transport is 6445 ng m -3, followed by exposure during shopping (2584 ng m -3). Average exposure is lowest while sleeping (1153 ng m -3) and when doing home-based activities (1223 ng m -3). Full-time workers spend almost twice as much time in transport as the homemakers. As a result of the study design we measured in several different homes, shops, cars, etc. enabling a better insight in true overall exposure in those microenvironments. Other factors influencing personal exposure are: background concentrations and location of residence in an urban, suburban or rural environment.

  10. Exposure to Kynurenic Acid During Adolescence Produces Memory Deficits in Adulthood

    PubMed Central

    Akagbosu, Cynthia O.; Evans, Gretchen C.; Gulick, Danielle; Suckow, Raymond F.; Bucci, David J.

    2012-01-01

    The glia-derived molecule kynurenic acid (KYNA) is an antagonist of α7 nicotinic acetylcholine receptors and the glycineB binding site on n-methyl-d-aspartateglutamate receptors, both of which have critical roles in neural plasticity as well as learning and memory. KYNA levels are increased in the brains and cerebral spinal fluid of persons with schizophrenia, leading to the notion that changes in KYNA concentration might contribute to cognitive dysfunction associated with this disorder. Indeed, recent studies indicate that increasing endogenous KYNA concentration by administering l-kynurenine (L-KYN, the precursor of KYNA) impairs spatial as well as contextual learning and memory in adult rats. In the present study, rats were treated with L-KYN (100 mg/kg) throughout adolescence to increase endogenous KYNA concentration during this critical time in brain development. Rats were then tested drug-free as adults to test the hypothesis that exposure to elevated levels of KYNA during development may contribute to cognitive dysfunction later in life. Consistent with prior studies in which adult rats were treated acutely with L-KYN, juvenile rats exposed to increased KYNA concentration during adolescence exhibited deficits in contextual fear memory, but cue-specific fear memory was not impaired. In addition, rats treated with L-KYN as adolescents were impaired on a novel object recognition memory task when tested as adults. The memory deficits could not be explained by drug-induced changes in locomotor activity or shock sensitivity. Together, these findings add to the growing literature supporting the notion that exposure to increased concentration of KYNA may contribute to cognitive deficits typically observed in schizophrenia. PMID:21172906

  11. Physiological, molecular, and cellular mechanisms of impaired seawater tolerance following exposure of Atlantic salmon, Salmo salar, smolts to acid and aluminum

    USGS Publications Warehouse

    Monette, M.Y.; Yada, T.; Matey, V.; McCormick, S.D.

    2010-01-01

    We examined the physiological, molecular, and cellular mechanisms of impaired ion regulation in Atlantic salmon, Salmo salar, smolts following acute acid and aluminum (Al) exposure. Smolts were exposed to: control (pH 6.5, 3.4??gl-1 Al), acid and low Al (LAl: pH 5.4, 11??gl-1 Al), acid and moderate Al (MAl: pH 5.3, 42??gl-1 Al), and acid and high Al (HAl: pH 5.4, 56??gl-1 Al) for two and six days. At each time-point, smolts were sampled directly from freshwater treatment tanks and after a 24h seawater challenge. Exposure to acid/MAl and acid/HAl led to accumulation of gill Al, substantial alterations in gill morphology, reduced gill Na+/K+-ATPase (NKA) activity, and impaired ion regulation in both freshwater and seawater. Exposure to acid/MAl for six days also led to a decrease in gill mRNA expression of the apical Cl- channel (cystic fibrosis transmembrane conductance regulator I), increased apoptosis upon seawater exposure, an increase in the surface expression of mitochondria-rich cells (MRCs) within the filament epithelium of the gill, but reduced abundance of gill NKA-positive MRCs. By contrast, smolts exposed to acid and the lowest Al concentration exhibited minor gill Al accumulation, slight morphological modifications in the gill, and impaired seawater tolerance in the absence of a detectable effect on freshwater ion regulation. These impacts were accompanied by decreased cell proliferation, a slight increase in the surface expression of MRCs within the filament epithelium, but no impact on gill apoptosis or total MRC abundance was observed. However, MRCs in the gills of smolts exposed to acid/LAl exhibited morphological alterations including decreased size, staining intensity, and shape factor. We demonstrate that the seawater tolerance of Atlantic salmon smolts is extremely sensitive to acute exposure to acid and low levels of Al, and that the mechanisms underlying this depend on the time-course and severity of Al exposure. We propose that when smolts are

  12. Physiological, molecular, and cellular mechanisms of impaired seawater tolerance following exposure of Atlantic salmon, Salmo salar, smolts to acid and aluminum.

    PubMed

    Monette, Michelle Y; Yada, Takashi; Matey, Victoria; McCormick, Stephen D

    2010-08-01

    We examined the physiological, molecular, and cellular mechanisms of impaired ion regulation in Atlantic salmon, Salmo salar, smolts following acute acid and aluminum (Al) exposure. Smolts were exposed to: control (pH 6.5, 3.4 micrpg l(-1) Al), acid and low Al (LAl: pH 5.4, 11 microg l(-1) Al), acid and moderate Al (MAl: pH 5.3, 42 microg l(-1) Al), and acid and high Al (HAl: pH 5.4, 56 microg l(-1) Al) for two and six days. At each time-point, smolts were sampled directly from freshwater treatment tanks and after a 24h seawater challenge. Exposure to acid/MAl and acid/HAl led to accumulation of gill Al, substantial alterations in gill morphology, reduced gill Na(+)/K(+)-ATPase (NKA) activity, and impaired ion regulation in both freshwater and seawater. Exposure to acid/MAl for six days also led to a decrease in gill mRNA expression of the apical Cl(-) channel (cystic fibrosis transmembrane conductance regulator I), increased apoptosis upon seawater exposure, an increase in the surface expression of mitochondria-rich cells (MRCs) within the filament epithelium of the gill, but reduced abundance of gill NKA-positive MRCs. By contrast, smolts exposed to acid and the lowest Al concentration exhibited minor gill Al accumulation, slight morphological modifications in the gill, and impaired seawater tolerance in the absence of a detectable effect on freshwater ion regulation. These impacts were accompanied by decreased cell proliferation, a slight increase in the surface expression of MRCs within the filament epithelium, but no impact on gill apoptosis or total MRC abundance was observed. However, MRCs in the gills of smolts exposed to acid/LAl exhibited morphological alterations including decreased size, staining intensity, and shape factor. We demonstrate that the seawater tolerance of Atlantic salmon smolts is extremely sensitive to acute exposure to acid and low levels of Al, and that the mechanisms underlying this depend on the time-course and severity of Al

  13. Population exposure to ultraviolet radiation in Finland 1920-1995: Exposure trends and a time-series analysis of exposure and cutaneous melanoma incidence

    SciTech Connect

    Kojo, Katja . E-mail: katja.kojo@uta.fi; Jansen, Christer T.; Nybom, Pia; Huurto, Laura; Laihia, Jarmo; Ilus, Taina; Auvinen, Anssi

    2006-05-15

    Ultraviolet radiation (UVR) is the principal cause of cutaneous malignant melanoma (CMM). However, the relation between CMM and UVR exposure is not clear. We present the trends of population exposure to UVR and conduct a time-series analysis of the relation between UVR exposure and incidence of CMM. Data on CMM incidence were obtained from the Finnish Cancer Registry. Clothing coverage of the body was scored from archival photographs and the proportion of uncovered skin was used as a measure of solar exposure. Information on the number of sunny resort holidays, duration of annual holidays, and sunscreen sales were obtained from various sources. Exposed skin area doubled from 1920 to 1985. The average duration of annual holidays increased 30-fold. The number of sunny resort holidays and the sales of sunscreens increased rapidly from 1980. CMM was most strongly associated with solar exposure of 5-19 years earlier. There is a considerable decrease in clothing coverage during the 20th century. UVR exposure preceding CMM occurrence 4 years or less does not appear relevant, whereas the period 5-19 years prior to CMM occurrence might be the most relevant period. However, findings of ecological studies may not be applicable at the individual level.

  14. Influence of different anoxic time exposures on active biomass, protozoa and filamentous bacteria in activated sludge.

    PubMed

    Rodriguez-Perez, S; Fermoso, F G; Arnaiz, C

    2016-01-01

    Medium-sized wastewater treatment plants are considered too small to implement anaerobic digestion technologies and too large for extensive treatments. A promising option as a sewage sludge reduction method is the inclusion of anoxic time exposures. In the present study, three different anoxic time exposures of 12, 6 and 4 hours have been studied to reduce sewage sludge production. The best anoxic time exposure was observed under anoxic/oxic cycles of 6 hours, which reduced 29.63% of the biomass production compared with the oxic control conditions. The sludge under different anoxic time exposures, even with a lower active biomass concentration than the oxic control conditions, showed a much higher metabolic activity than the oxic control conditions. Microbiological results suggested that both protozoa density and abundance of filamentous bacteria decrease under anoxic time exposures compared to oxic control conditions. The anoxic time exposures 6/6 showed the highest reduction in both protozoa density, 37.5%, and abundance of filamentous bacteria, 41.1%, in comparison to the oxic control conditions. The groups of crawling ciliates, carnivorous ciliates and filamentous bacteria were highly influenced by the anoxic time exposures. Protozoa density and abundance of filamentous bacteria have been shown as promising bioindicators of biomass production reduction.

  15. Influence of different anoxic time exposures on active biomass, protozoa and filamentous bacteria in activated sludge.

    PubMed

    Rodriguez-Perez, S; Fermoso, F G; Arnaiz, C

    2016-01-01

    Medium-sized wastewater treatment plants are considered too small to implement anaerobic digestion technologies and too large for extensive treatments. A promising option as a sewage sludge reduction method is the inclusion of anoxic time exposures. In the present study, three different anoxic time exposures of 12, 6 and 4 hours have been studied to reduce sewage sludge production. The best anoxic time exposure was observed under anoxic/oxic cycles of 6 hours, which reduced 29.63% of the biomass production compared with the oxic control conditions. The sludge under different anoxic time exposures, even with a lower active biomass concentration than the oxic control conditions, showed a much higher metabolic activity than the oxic control conditions. Microbiological results suggested that both protozoa density and abundance of filamentous bacteria decrease under anoxic time exposures compared to oxic control conditions. The anoxic time exposures 6/6 showed the highest reduction in both protozoa density, 37.5%, and abundance of filamentous bacteria, 41.1%, in comparison to the oxic control conditions. The groups of crawling ciliates, carnivorous ciliates and filamentous bacteria were highly influenced by the anoxic time exposures. Protozoa density and abundance of filamentous bacteria have been shown as promising bioindicators of biomass production reduction. PMID:27508364

  16. Nitrous oxide and occupational exposure: it's time to stop laughing.

    PubMed

    Kugel, G; Norris, L H; Zive, M A

    1989-01-01

    Although nitrous oxide (N(2)O) has been widely used since 1844, in recent years it has been implicated in a number of serious health hazards such as reproductive, nerve, liver, and kidney disorders. The National Institute of Safety and Health (NIOSH) recommends a limit of 25 ppm for chronic exposure to N(2)O in the dental office. Our study monitored ambient N(2)O levels in the dental office. N(2)O levels were compared for procedures performed in open clinics and private operatories as well as with and without a gas-scavenging system. Measurements were taken in the Dental Breathing Zone (DBZ) and Dental Chair Foot (DCF) at regular intervals. A four- to eightfold increase in average N(2)O levels was noted in the DBZ for unscavenged versus scavenged procedures. A three- to fourfold increase for unscavenged versus scavenged procedures was similarly noted in the DCF. N(2)O were significantly higher in private operatories than in open clinics, due to limited room volumes and in the DBZ over the DCF, due to mask leakage and increased oral exhalation. Scavenged N(2)O levels for both operatory types did not meet NIOSH guidelines. In contrast to previous studies using any form of gas removal, our study shows a significant decrease in N(2)O level achieved with an adequate scavenger system. With only four states regulating the use of N(2)O, and with concern over its deleterious effects growing, additional states and the federal government are expected to enact legislation regulating the use of N(2)O in the near future. PMID:2490056

  17. Valproic Acid Induced Hyperammonemia in a Long Time Treated Patient

    PubMed Central

    Seide, Margaret; Stern, Robert G.

    2016-01-01

    We report a case of a patient who had been on long time valproic acid for treatment of bipolar affective disorder. While being an inpatient, serology ammonia level testing revealed a very high ammonia level despite being asymptomatic. Dual therapy of carnitine and lactulose was provided to the patient for treatment of the hyperammonemia. It should also be noted that, during this treatment, valproic acid was not stopped. Consequently, this case illustrates that patients can present asymptomatically despite very high ammonia levels and hyperammonemia can occur in chronic valproic acid despite not increasing the dose of the medication and psychiatrists do not need to discontinue valproic acid in the presence of elevated levels of ammonia if the patient shows no signs of encephalopathy or delirium. PMID:27516916

  18. Valproic Acid Induced Hyperammonemia in a Long Time Treated Patient.

    PubMed

    Aiyer, Rohit; Seide, Margaret; Stern, Robert G

    2016-01-01

    We report a case of a patient who had been on long time valproic acid for treatment of bipolar affective disorder. While being an inpatient, serology ammonia level testing revealed a very high ammonia level despite being asymptomatic. Dual therapy of carnitine and lactulose was provided to the patient for treatment of the hyperammonemia. It should also be noted that, during this treatment, valproic acid was not stopped. Consequently, this case illustrates that patients can present asymptomatically despite very high ammonia levels and hyperammonemia can occur in chronic valproic acid despite not increasing the dose of the medication and psychiatrists do not need to discontinue valproic acid in the presence of elevated levels of ammonia if the patient shows no signs of encephalopathy or delirium. PMID:27516916

  19. Perfluorooctanoic acid exposure for 28 days affects glucose homeostasis and induces insulin hypersensitivity in mice

    NASA Astrophysics Data System (ADS)

    Yan, Shengmin; Zhang, Hongxia; Zheng, Fei; Sheng, Nan; Guo, Xuejiang; Dai, Jiayin

    2015-06-01

    Perfluoroalkyl acids (PFAAs) are widely used in many applications due to their unique physical and chemical characteristics. Because of the increasing prevalence of metabolic syndromes, including obesity, dyslipidemia and insulin resistance, concern has arisen about the roles of environmental pollutants in such diseases. Earlier epidemiologic studies showed a potential association between perfluorooctanoic acid (PFOA) and glucose metabolism, but how PFOA influences glucose homeostasis is still unknown. Here, we report on the modulation of the phosphatidylinositol 3-kinase-serine/threonine protein kinase (PI3K-AKT) signaling pathway in the livers of mice after 28 d of exposure to PFOA. Compared with normal mice, PFOA exposure significantly decreased the expression of the phosphatase and tensin homologue (PTEN) protein and affected the PI3K-AKT signaling pathway in the liver. Tolerance tests further indicated that PFOA exposure induced higher insulin sensitivity and glucose tolerance in mice. Biochemical analysis revealed that PFOA exposure reduced hepatic glycogen synthesis, which might be attributed to gluconeogenesis inhibition. The levels of several circulating proteins were altered after PFOA exposure, including proteins potentially related to diabetes and liver disease. Our results suggest that PFOA affected glucose metabolism and induced insulin hypersensitivity in mice.

  20. Controlled exposures of volunteers to respirable carbon and sulfuric acid aerosols

    SciTech Connect

    Anderson, K.R.; Avol, E.L.; Edwards, S.A.; Shamoo, D.A.; Ruchuan Peng; Linn, W.S.; Hackney, J.D. )

    1992-06-01

    Respirable carbon or fly ash particles are suspected to increase the respiratory toxicity of coexisting acidic air pollutants, by concentrating acid on their surfaces and so delivering it efficiently to the lower respiratory tract. To investigate this issue, the authors exposed 15 healthy and 15 asthmatic volunteers in a controlled-environment chamber to four test atmospheres: (1) clean air; (2) 0.5-{mu}m H{sub 2}SO{sub 4} aerosol at {approx}100 {mu}g/m{sup 3}, generated from water solution; (3) 0.5-{mu}m carbon aerosol at {approx}250 {mu}g/m{sup 3}, generated from highly pure carbon black with specific surface area comparable to ambient pollution particles; and (4) carbon as in (3) plus {approx}100 {mu}g/m{sup 3} of ultrafine H{sub 2}SO{sub 4} aerosol generated from fuming sulfuric acid. Electron microscopy showed that nearly all acid in (4) became attached to carbon particle surfaces, and that most particles remained in the sub-{mu}m size range. Exposures were performed double-blind, 1 week apart. They lasted 1 hr each, with alternate 10-min periods of heavy exercise (ventilation {approx}50 L/min) and rest. Subjects gargled citrus juice before exposure to suppress airway ammonia. Lung function and symptoms were measured pre-exposure, after initial exercise, and at end-exposure. Bronchial reactivity to methacholine was measured after exposure. Statistical analyses tested for effects of H{sub 2}SO{sub 4} or carbon, separate or interactive, on health measures.

  1. The effect of ozone exposure on rat alveolar macrophage arachidonic acid metabolism

    SciTech Connect

    Madden, M.C.; Eling, T.E.; Dailey, L.A.; Friedman, M. )

    1991-01-01

    Rat alveolar macrophages were prelabeled with {sup 3}H-arachidonic acid ({sup 3}H-AA) and exposed to air or O3 (0.1-1.0 ppm) in vitro for 2 h. Alveolar macrophages released 3.6-fold more tritium at the 1.0 ppm exposure concentration compared with air-exposed macrophages. A significantly increased production of several {sup 3}H-AA metabolites, including 6-keto-PGF1 alpha, thromboxane B2, 12-hydroxy-5,8,10-heptadecatrienoic acid, prostaglandins E2 and D2, leukotrienes B4 and D4, and 15-hydroxyeicosatetraenoic acid was formed by macrophages exposed to 1.0 ppm O3 compared with air-exposed macrophages as determined by high performance liquid chromatography (HPLC) analysis. O3 exposure did not alter macrophage {sup 3}H-AA metabolism in response to calcium ionophore A23187. The largest tritiated peak observed in the HPLC chromatograms of O{sub 3}-exposed cells was a polar complex of products that contained various phospholipids and neutral lipids (including diacylglycerol) and possibly degradation products of {sup 3}H-AA and some of its metabolites. These changes in macrophage arachidonic acid metabolism may play an important role in the lung response to O{sub 3} exposure in vivo.

  2. REAL-TIME MODELING OF MOTOR VEHICLE EMISSIONS FOR ESTIMATING HUMAN EXPOSURES NEAR ROADWAYS

    EPA Science Inventory

    The United States Environmental Protection Agency's (EPA) National Exposure Research Laboratory is developing a real-time model of motor vehicle emissions to improve the methodology for modeling human exposure to motor vehicle emissions. The overall project goal is to develop ...

  3. Chronic Dietary Exposure to Aristolochic Acid and Kidney Function in Native Farmers from a Croatian Endemic Area and Bosnian Immigrants

    PubMed Central

    Jelaković, Bojan; Karanović, Sandra; Dika, Živka; Kos, Jelena; Dickman, Kathleen; Šekoranja, Maja; Poljičanin, Tamara; Mišić, Maja; Premužić, Vedran; Abramović, Mirta; Matijević, Vesna; Miletić Medved, Marica; Cvitković, Ante; Edwards, Karen; Fuček, Mirjana; Leko, Ninoslav; Teskera, Tomislav; Laganović, Mario; Čvorišćec, Dubravka; Grollman, Arthur P.

    2015-01-01

    Background and objectives Improvements in agricultural practices in Croatia have reduced exposure to consumption of aristolochic acid-contaminated flour and development of endemic (Balkan) nephropathy. Therefore, it was hypothesized that Bosnian immigrants who settled in an endemic area in Croatia 15–30 years ago would be at lower risk of developing endemic nephropathy because of reduced exposure to aristolochic acid. To test this hypothesis, past and present exposure to aristolochic acid, proximal tubule damage as a hallmark of endemic nephropathy, and prevalence of CKD in Bosnian immigrants were analyzed. Design, setting, participants, & measurements In this cross-sectional observational study from 2005 to 2010, 2161 farmers were divided into groups: indigenous inhabitants from endemic nephropathy and nonendemic nephropathy villages and Bosnian immigrants; α-1 microglobulin-to-creatinine ratio >31.5 mg/g and eGFR<60 ml/min per 1.73 m2 were considered to be abnormal. Results CKD and proximal tubule damage prevalence was significantly lower in Bosnian immigrants than inhabitants of endemic nephropathy villages (6.9% versus 16.6%; P<0.001; 1.3% versus 7.3%; P=0.003, respectively); 20 years ago, Bosnian immigrants observed fewer Aristolochia clematitis in cultivated fields (41.9% versus 67.8%) and fewer seeds among wheat seeds (6.1% versus 35.6%) and ate more purchased than homemade bread compared with Croatian farmers from endemic nephropathy villages (38.5% versus 14.8%, P<0.001). Both Croatian farmers and Bosnian immigrants observe significantly fewer Aristolochia plants growing in their fields compared with 15–30 years ago. Prior aristolochic acid exposure was associated with proximal tubule damage (odds ratio, 1.64; 95% confidence interval, 1.04 to 2.58; P=0.02), whereas present exposure was not (odds ratio, 1.31; 95% confidence interval, 0.75 to 2.30; P=0.33). Furthermore, immigrant status was an independent negative predictor of proximal tubule damage

  4. Laminaria japonica increases plasma exposure of glycyrrhetinic acid following oral administration of Liquorice extract in rats.

    PubMed

    Zhao, Wei-Man; Jiang, Shu-Wen; Chen, Yang; Zhong, Ze-Yu; Wang, Zhong-Jian; Zhang, Mian; Li, Ying; Xu, Ping; Liu, Li; Liu, Xiao-Dong

    2015-07-01

    The present study was designed to investigate the effects of Laminaria japonica (Laminaria) on pharmacokinetics of glycyrrhetinic acid (GA) following oral administration of Liquorice extract in rats. Following oral administrations of single-dose and multi-dose Liquorice extract and Liquorice-Laminaria extract, respectively, plasma samples were obtained at various times and the concentrations of GA, liquiritigenin, and isoliquiritigenin were measured by LC-MS. The effects of Laminaria extract on pharmacokinetics of GA were also investigated, following single-dose and multidose of glycyrrhizic acid (GL). The effects of Laminaria extract on intestinal absorption of GA and GL were studied using the in situ single-pass intestinal perfusion model. The metabolism of GL to GA in the contents of small and large intestines was also studied. The results showed Liquorice-Laminaria extract markedly increased the plasma concentration of GA, accompanied by a shorter Tmax. Similar alteration was observed following multidose administration. However, pharmacokinetics of neither liquiritigenin nor isoliquiritigenin was affected by Laminaria. Similarly, Laminaria markedly increased concentration and decreased Tmax of GA following oral GL were observed. The data from the intestinal perfusion model showed that Laminaria markedly increased GL absorption in duodenum and jejunum, but did not affect the intestinal absorption of GA. It was found that Laminaria enhanced the metabolism of GL to GA in large intestine. In conclusion, Laminaria increased plasma exposures of GA following oral administration of liquorice or GL, which partly resulted from increased intestinal absorption of GL and metabolism of GL to GA in large intestine.

  5. A network-based approach for estimating pedestrian journey-time exposure to air pollution.

    PubMed

    Davies, Gemma; Whyatt, J Duncan

    2014-07-01

    Individual exposure to air pollution depends not only upon pollution concentrations in the surrounding environment, but also on the volume of air inhaled, which is determined by an individual's physiology and activity level. This study focuses on journey-time exposure, using network analysis in a GIS environment to identify pedestrian routes between multiple origins and destinations throughout the city of Lancaster, North West England. For each segment of a detailed footpath network, exposure was calculated accounting for PM2.5 concentrations (estimated using an atmospheric dispersion model) and respiratory minute volume (varying between individuals and with slope). For each of the routes generated the cumulative exposure to PM2.5 was estimated, allowing for easy comparison between multiple routes. Significant variations in exposure were found between routes depending on their geography, as well as in response to variations in background concentrations and meteorology between days. Differences in physiological characteristics such as age or weight were also seen to impact journey-time exposure considerably. In addition to assessing exposure for a given route, the approach was used to identify alternative routes that minimised journey-time exposure. Exposure reduction potential varied considerably between days, with even subtle shifts in route location, such as to the opposite side of the road, showing significant benefits. The method presented is both flexible and scalable, allowing for the interactions between physiology, activity level, pollution concentration and journey duration to be explored. In enabling physiology and activity level to be integrated into exposure calculations a more comprehensive estimate of journey-time exposure can be made, which has potential to provide more realistic inputs for epidemiological studies.

  6. Immune response of the bay scallop, Argopecten irradians, after exposure to the algicide palmitoleic acid.

    PubMed

    Chi, Cheng; Giri, Sib Sankar; Jun, Jin Woo; Yun, Saekil; Kim, Hyoun Joong; Kim, Sang Guen; Park, Se Chang

    2016-10-01

    Palmitoleic acid (PA) is an effective algicide against the toxin-producing dinoflagellate Alexandrium tamarense; however, its effects on the immune system of the edible bay scallop Argopecten irradians are unclear. Therefore, we investigated the effects of PA on the immune response in A. irradians by assessing total haemocyte counts (THC), alkaline phosphatase activity (ALP), nitrite oxide (NO), glutathione (GSH), and lactate dehydrogenase (LDH) levels, as well as the expression of immune-related genes (FREP, PGRP, HSP90, MnSOD, and Cu/ZnSOD) at various hours post-exposure (hpe) to the compound. THC decreased in PA-treated groups, whereas ALP increased significantly in all of the PA treatment groups at 3 hpe, after which it significantly decreased. The LDH and NO levels were significantly enhanced in the high and medium concentration group. Notably, the GSH level increased in all PA treatment groups at each time interval. Our study revealed that after treatment with different concentrations of PA, variable effects on the expression of genes involved in the immune system response were observed. The results of our study demonstrate that immersing scallops in PA at effective concentrations could result in differential effects on immune system responses and expression of immune-related genes. Specifically, PA may disrupt the endocrine system or affect signal transduction pathways in the scallops. Therefore, the present study highlights the potential risk of using the PA as an algicide to control algal bloom outbreaks in the marine environment.

  7. Valproic Acid Exposure during Early Postnatal Gliogenesis Leads to Autistic-like Behaviors in Rats

    PubMed Central

    Mony, Tamanna Jahan; Lee, Jae Won; Dreyfus, Cheryl; DiCicco-Bloom, Emanuel; Lee, Hee Jae

    2016-01-01

    Objective We reported that postnatal exposure of rats to valproic acid (VPA) stimulated proliferation of glial precursors during cortical gliogenesis. However, there are no reports whether enhanced postnatal gliogenesis affects behaviors related to neuropsychiatric disorders. Methods After VPA treatment during the postnatal day (PND) 2 to PND 4, four behavioral test, such as open field locomotor test, elevated plus maze test, three-chamber social interaction test, and passive avoidance test, were performed at PND 21 or 22. Results VPA treated rats showed significant hyperactive behavior in the open field locomotor test (p<0.05). Moreover, the velocity of movement in the VPA group was increased by 69.5% (p<0.01). In the elevated plus maze test, VPA exposed rats expressed significantly lower percentage of time spent on and of entries into open arms more than the control group (p<0.05). Also, both sociability and social preference indices with strangers in the three-chamber social interaction test were significantly lower in the VPA exposed rats (p<0.05). Conclusion Our results suggest that altered glial cell development is another locus at which pathogenetic factors can operate to contribute to the neurodevelopmental disorder. PMID:27776385

  8. Immune response of the bay scallop, Argopecten irradians, after exposure to the algicide palmitoleic acid.

    PubMed

    Chi, Cheng; Giri, Sib Sankar; Jun, Jin Woo; Yun, Saekil; Kim, Hyoun Joong; Kim, Sang Guen; Park, Se Chang

    2016-10-01

    Palmitoleic acid (PA) is an effective algicide against the toxin-producing dinoflagellate Alexandrium tamarense; however, its effects on the immune system of the edible bay scallop Argopecten irradians are unclear. Therefore, we investigated the effects of PA on the immune response in A. irradians by assessing total haemocyte counts (THC), alkaline phosphatase activity (ALP), nitrite oxide (NO), glutathione (GSH), and lactate dehydrogenase (LDH) levels, as well as the expression of immune-related genes (FREP, PGRP, HSP90, MnSOD, and Cu/ZnSOD) at various hours post-exposure (hpe) to the compound. THC decreased in PA-treated groups, whereas ALP increased significantly in all of the PA treatment groups at 3 hpe, after which it significantly decreased. The LDH and NO levels were significantly enhanced in the high and medium concentration group. Notably, the GSH level increased in all PA treatment groups at each time interval. Our study revealed that after treatment with different concentrations of PA, variable effects on the expression of genes involved in the immune system response were observed. The results of our study demonstrate that immersing scallops in PA at effective concentrations could result in differential effects on immune system responses and expression of immune-related genes. Specifically, PA may disrupt the endocrine system or affect signal transduction pathways in the scallops. Therefore, the present study highlights the potential risk of using the PA as an algicide to control algal bloom outbreaks in the marine environment. PMID:27542615

  9. Atlantic salmon (Salmo salar L.) smolts require more than two weeks to recover from acidic water and aluminium exposure.

    PubMed

    Nilsen, Tom O; Ebbesson, Lars O E; Handeland, Sigurd O; Kroglund, Frode; Finstad, Bengt; Angotzi, Anna R; Stefansson, Sigurd O

    2013-10-15

    The detrimental effects of acid rain and aluminium (Al) on salmonids have been extensively studied, yet knowledge about the extent and rate of potential recovery after exposures to acid and Al episodes is limited. Atlantic salmon smolts in freshwater (FW) were exposed for 2 and 7-day episodes (ACID2 and ACID7, respectively) to low pH (5.7±0.2) and inorganic aluminium (Ali; 40±4 μg) and then transferred to good water quality, control water (CW; pH 6.8±0.1; <14±2 μg Ali). Al accumulation on gills after 2 and 7 days of acid/Al exposure was 35.3±14.1 and 26.6±1.8 μg g(-1) dry weight, respectively. These elevated levels decreased 2 days post transfer to CW and remained higher than in control (CON; 5-10 μg Ali) for two weeks. Plasma Na(+) levels in ACID2 and ACID7 smolts decreased to 141±0.8 and 138.6±1.4mM, respectively, and remained significantly lower than CON levels for two weeks post transfer to CW. Similarly, plasma Cl(-) levels in ACID7 smolts (124.3±2.8mM) were significantly lower than in CON, with Cl(-) levels remaining significantly lower in ACID7 (126.2±4.8 mM) and ACID2 (127.6±3.7 mM) than in CON following 9 and 14 days post-transfer to CW, respectively. ACID2 and ACID7 smolts sustained elevated plasma glucose levels post transfer to CW suggesting elevated stress for more than a week following exposure. While gill Na(+), K(+)-ATPase (NKA) activity was only slightly affected in ACID2 and not in ACID7 smolts in FW, acid/Al exposure resulted in a transient decrease in NKA activity following SW exposure in both groups. Acid/Al episodes had limited impact on isoform specific NKA α-subunit mRNA during exposure. However, the transfer of ACID2 and ACID7 smolts to CW showed an increase in NKAα1a mRNA (the FW isoform) and inhibited the up-regulation of NKAα1b (the SW isoform), probably resulting in higher abundance of the enzyme favouring ion uptake. Gill caspase 3B gene transcription did not change in acid/Al treated smolts, indicating no increased

  10. Atlantic salmon (Salmo salar L.) smolts require more than two weeks to recover from acidic water and aluminium exposure.

    PubMed

    Nilsen, Tom O; Ebbesson, Lars O E; Handeland, Sigurd O; Kroglund, Frode; Finstad, Bengt; Angotzi, Anna R; Stefansson, Sigurd O

    2013-10-15

    The detrimental effects of acid rain and aluminium (Al) on salmonids have been extensively studied, yet knowledge about the extent and rate of potential recovery after exposures to acid and Al episodes is limited. Atlantic salmon smolts in freshwater (FW) were exposed for 2 and 7-day episodes (ACID2 and ACID7, respectively) to low pH (5.7±0.2) and inorganic aluminium (Ali; 40±4 μg) and then transferred to good water quality, control water (CW; pH 6.8±0.1; <14±2 μg Ali). Al accumulation on gills after 2 and 7 days of acid/Al exposure was 35.3±14.1 and 26.6±1.8 μg g(-1) dry weight, respectively. These elevated levels decreased 2 days post transfer to CW and remained higher than in control (CON; 5-10 μg Ali) for two weeks. Plasma Na(+) levels in ACID2 and ACID7 smolts decreased to 141±0.8 and 138.6±1.4mM, respectively, and remained significantly lower than CON levels for two weeks post transfer to CW. Similarly, plasma Cl(-) levels in ACID7 smolts (124.3±2.8mM) were significantly lower than in CON, with Cl(-) levels remaining significantly lower in ACID7 (126.2±4.8 mM) and ACID2 (127.6±3.7 mM) than in CON following 9 and 14 days post-transfer to CW, respectively. ACID2 and ACID7 smolts sustained elevated plasma glucose levels post transfer to CW suggesting elevated stress for more than a week following exposure. While gill Na(+), K(+)-ATPase (NKA) activity was only slightly affected in ACID2 and not in ACID7 smolts in FW, acid/Al exposure resulted in a transient decrease in NKA activity following SW exposure in both groups. Acid/Al episodes had limited impact on isoform specific NKA α-subunit mRNA during exposure. However, the transfer of ACID2 and ACID7 smolts to CW showed an increase in NKAα1a mRNA (the FW isoform) and inhibited the up-regulation of NKAα1b (the SW isoform), probably resulting in higher abundance of the enzyme favouring ion uptake. Gill caspase 3B gene transcription did not change in acid/Al treated smolts, indicating no increased

  11. Exposure assessment of food preservatives (sulphites, benzoic and sorbic acid) in Austria.

    PubMed

    Mischek, Daniela; Krapfenbauer-Cermak, Christine

    2012-01-01

    An exposure assessment was performed to estimate the potential intake of preservatives in the Austrian population. Food consumption data of different population groups, such as preschool children aged 3-6 years, female and male adults aged 19-65 years were used for calculation. Levels of the preservatives in food were derived from analyses conducted from January 2007 to August 2010. Dietary intakes of the preservatives were estimated and compared to the respective acceptable daily intakes (ADIs). In the average-intake scenario, assuming that consumers randomly consume food products that do or do not contain food additives, estimated dietary intakes of all studied preservatives are well below the ADI for all population groups. Sulphite exposure accounted for 34%, 84% and 89% of the ADI in preschool children, females and males, respectively. The mean estimated daily intake of benzoic acid was 32% (preschool children), 31% (males) and 36% (females) of the ADI. Sorbic acid intakes correspond to 7% of the ADI in preschool children and 6% of the ADI in adults. In the high-intake scenario assuming that consumers always consume food products that contain additives and considering a kind of brand loyalty of consumers, the ADI is exceeded for sulphites among adults (119 and 124%, respectively). Major contributors to the total intake of sulphites were wine and dried fruits for adults. Mean estimated dietary intakes of benzoic acid exceeded the ADI in all population groups, 135% in preschool children, 124% in females and 118% of the ADI in males, respectively. Dietary intakes of sorbic acid are well below the ADI, accounting for a maximum of 30% of the ADI in preschool children. The highest contributors to benzoic and sorbic acid exposure were fish and fish products mainly caused by high consumption data of this large food group, including also mayonnaise-containing fish salads. Other important sources of sorbic acid were bread, buns and toast bread and fruit and vegetable

  12. Lead exposure assessment from study near a lead-acid battery factory in China.

    PubMed

    Chen, Laiguo; Xu, Zhencheng; Liu, Ming; Huang, Yumei; Fan, Ruifang; Su, Yanhua; Hu, Guocheng; Peng, Xiaowu; Peng, Xiaochun

    2012-07-01

    The production of lead-acid battery in China covered about one-third of the world total output and there are more than 2000 lead-acid battery factories. They may cause the major environment lead pollution. Blood lead levels of several hundreds of residents were over 100 μg/L due to the waste discharges from a lead-acid battery factory in Heyuan, Guangdong province. This study aimed to find out the environmental lead sources, the human lead exposure pathways, and the amplitudes from a lead-acid battery factory. The study results showed that lead levels in soil, dust, tree leaves and human blood declined with the distances increased from the production site. Twenty nine of 32 participants had blood lead levels of over 100 μg/L with an exceptional high value of 639 μg/L for one child. This result suggested that the lead-acid battery production from this factory has caused the elevated lead levels in its neighboring environment and residents. Dust intake was the dominant exposure pathway for humans (over 90%). The lead levels found in adult and toddler (6.19 and 50.1 μg/kg/d, respectively) in the polluted area were far higher than the provisional tolerable weekly intake (PTWI) of 25 μg/kg body weight (translated into 3.5 μg/kg/d), which was established by the joint FAO/WHO Expert Committee. Blood lead levels within the family members were strongly correlated with the house dust lead levels. Our results in this study suggested that further studies in this area should be performed to assess human exposure and relevant human health risks from living close to lead-acid battery factories.

  13. Determination of Exposure to the Alternaria Mycotoxin Tenuazonic Acid and Its Isomer allo-Tenuazonic Acid in a German Population by Stable Isotope Dilution HPLC-MS(3).

    PubMed

    Hövelmann, Yannick; Hickert, Sebastian; Cramer, Benedikt; Humpf, Hans-Ulrich

    2016-08-31

    The content of the Alternaria toxin tenuazonic acid and its isomer allo-tenuazonic acid was quantitated in urine of a German cohort (n = 48) using a newly developed and successfully validated solid phase extraction based stable isotope dilution HPLC-MS(3) method. Tenuazonic acid was detected in all of the samples and quantifiable in 97.9% of these samples in a range of 0.16-44.4 ng/mL (average = 6.58 ng/mL) or 0.07-63.8 ng/mg creatinine (average = 8.13 ng/mg creatinine). allo-Tenuazonic acid was for the first time detected in human urine (95.8% of the samples positive) and quantitated in 68.8% of the samples in a range of 0.11-5.72 ng/mL (average = 1.25 ng/mL) or 0.08-10.1 ng/mg creatinine (average = 1.52 ng/mg creatinine), representing 3.40-25.0% of the sum of both isomers (average = 12.4%). Food-frequency questionnaires were used to document food consumption of study participants to correlate mycotoxin exposure to nutritional habits. Although no statistically significant correlation between consumption of a specific food and urinary excretion of tenuazonic acid could be determined, a trend regarding elevated intake of cereal products and higher excretion of tenuazonic acid was evident. On the basis of these results, a provisional mean daily intake (PDI) for both tenuazonic acid and allo-tenuazonic acid was calculated, being 0.183 and 0.025 μg/kg body weight, respectively. A combined mean PDI for both isomers amounts to 0.208 μg/kg body weight with the highest individual PDI for one of the participants (1.582 μg/kg body weight) slightly exceeding the threshold of toxicological concern assumed for tenuazonic acid by the European Food Safety Authority of 1.500 μg/kg body weight. This is the first study to investigate the tenuazonic acid content in human urine of a larger sample cohort enabling the calculation of PDIs for tenuazonic acid and allo-tenuazonic acid. PMID:27452834

  14. Effects of exposure to lead among lead-acid battery factory workers in Sudan.

    PubMed

    Awad el Karim, M A; Hamed, A S; Elhaimi, Y A; Osman, Y; el Karim, M A

    1986-01-01

    Health effects of occupational exposure to lead were investigated among 92 exposed workers in lead-acid battery factory and 40 nonexposed workers serving as a control group from an oil mill in Khartoum North industrial area. The two groups were closely similar in age, stature, body weight, and socioeconomic conditions. A highly significant increase (P less than .01) was recorded in blood lead, urinary coproporphyrin, and basophilic stippled red blood cells of the exposed group in comparison to the control group. Central nervous system symptoms (insomnia, fatigue, weakness, and drowsiness) were reported by 50% and other symptoms such as abdominal colic and constipation were reported by 41% of the exposed group. Blue line on the gum was detected only on 2% of the exposed group. Strong associations between exposure to lead and the prevalence of central nervous system symptoms, abdominal colic, and constipation were recorded. Exposure to exceedingly high levels of lead in the working environment causes adverse health effects.

  15. Problems in the estimation of human exposure to components of acid precipitation precursors.

    PubMed

    Ferris, B G; Spengler, J D

    1985-11-01

    Problems associated with estimation of human exposure to ambient air pollutants are discussed. Ideally, we would prefer to have some indication of actual dose. For most pollutants this is not presently feasible. Specific problems discussed are adequacy of outdoor monitors; the need to correct for exposures and time spent indoors; the need to have particle size distributions described and the chemistry of the particles presented. These indicate the need to develop lightweight accurate and reliable personal monitors.

  16. Relation between oesophageal acid exposure and healing of oesophagitis with omeprazole in patients with severe reflux oesophagitis.

    PubMed Central

    Holloway, R H; Dent, J; Narielvala, F; Mackinnon, A M

    1996-01-01

    BACKGROUND/AIMS--Reducing oesophageal acid exposure by suppressing acid secretion with omeprazole is highly effective in healing reflux oesophagitis. Some patients with severe oesophagitis, fail to heal and whether this results from inadequate acid suppression or other factors is unclear. The aim of this study, was to investigate the relation between oesophageal acid exposure and healing in patients with severe reflux oesophagitis treated with omeprazole. METHODS--Sixty one patients with grade 3 or 4 ulcerative oesophagitis were treated for eight weeks with omeprazole 20 mg every morning. Those patients unhealed at eight weeks were treated with 40 mg every morning for a further eight weeks. Endoscopy and 24 hour oesophageal pH monitoring were performed before treatment and at the end of each treatment phase while receiving treatment. RESULTS--Thirty per cent of patients failed to heal with the 20 mg dose. Unhealed patients had greater total 24 hour oesophageal acid exposure before treatment, and while receiving treatment also had greater acid exposure and a smaller reduction in acid exposure than did patients who healed. Forty seven per cent of the unhealed patients also failed to heal with the 40 mg dose. These patients had similar levels of acid exposure before treatment to those who healed, but had greater acid exposure while receiving treatment, particularly at night when supine. CONCLUSIONS--Patients with severe ulcerative oesophagitis who are refractory to omeprazole have greater oesophageal acid exposure while receiving treatment than responding patients. This is due to a reduced responsiveness to acid suppression, and is likely to be an important factor underlying the failure of the oesophagitis to heal. PMID:8707107

  17. Accounting for time-dependent covariates whose levels are influenced by exposure status.

    PubMed

    Weiss, N S; Dublin, S

    1998-07-01

    When measuring the association between an exposure and disease, one must decide whether to account for confounding or modifying variables whose levels are altered by the presence of the exposure. For example, to assess the impact of cessation of unopposed estrogen therapy on the occurrence of endometrial cancer, a researcher needs to consider the duration of the estrogen therapy, a strong risk factor for endometrial cancer, as a potential confounder or effect modifier. Duration of estrogen therapy, however, is itself influenced by the decision to stop the therapy (the "exposure" of interest). In such a case, two distinct approaches may be taken, depending upon the question being considered. One may wish to assess the degree to which the exposure predicts disease incidence, over and above the additional variable, at some later point in time. In this case, it is appropriate to consider the value of the other variable (for example, duration) at that later time. On the other hand, one may also wish to measure the rate of disease beginning at the time of cessation of the exposure, relative to the corresponding rate in persons with continuing exposure Here, the most appropriate analysis considers the level of the confounding variable (for example, duration) measured only until the time of exposure of interest occurs (for example, cessation of unopposed estrogen therapy). Examples are given to illustrate that the specific question being addressed dictates the handling of covariates of this type. PMID:9647909

  18. Preliminary exposure study to determine the effects of acid deposition on coated steel substrates. Final report

    SciTech Connect

    Moran, P.J.; Simpson, T.C.; Hampel, H.; David, G.D.; Shaw, B.A.

    1990-04-01

    The project involves the evaluation of the effects of acidic pollutants on painted metal substrates. The project examined a commercially available alkyd paint/primer system applied to a low carbon steel substrate exposed under a variety of simulated acidic conditions to determine the micro/macro effects of such exposure. The techniques that were identified as those most sensitive and applicable during the study include tensile adhesion testing, electrochemical impedance spectroscopy, and x-ray photoelectron spectroscopy. A novel electrochemical monitor was developed during this program that allowed the continual monitoring of coating degradation during chamber exposure. It was further found that a good correlation existed between tensile adhesion strength measurements and electrochemical impedance parameters. The program determined that the rate of degradation of the alkyd painted steel coupons was accelerated in the presence of SO2. This effect was most pronounced on samples that contained defects (scribes), that were allowed to form condensed (dew) during the exposure period and that had a horizontal orientation during exposure.

  19. Benzene exposure, assessed by urinary trans,trans-muconic acid, in urban children with elevated blood lead levels.

    PubMed Central

    Weaver, V M; Davoli, C T; Heller, P J; Fitzwilliam, A; Peters, H L; Sunyer, J; Murphy, S E; Goldstein, G W; Groopman, J D

    1996-01-01

    A pilot study was performed to evaluate the feasibility of using trans,trans-muconic acid (MA) as a biomarker of environmental benzene exposure. A secondary aim was to provide data on the extent of exposure to selected toxicants in a unique population consisting of inner-city children who were already overexposed to one urban hazard, lead. Potential sources of benzene were assessed by a questionnaire. Exposure biomarkers included urinary MA and cotinine and blood lead. Mean MA was 176.6 +/- 341.7 ng/mg creatinine in the 79 children who participated. A wide range of values was found with as many as 10.1%, depending on the comparison study, above the highest levels reported in adults not exposed by occupation. Mean MA was increased in children evaluated in the afternoon compared to morning, those at or above the median for time spent playing near the street, and those studied in the first half of the investigation. MA levels were not associated with blood lead or, consistently, with either questionnaire environmental tobacco smoke (ETS) data or cotinine. As expected, the mean blood lead level was elevated (23.6 micrograms/dl). Mean cotinine was also increased at 79.2 ng/mg creatinine. We conclude that the use of MA as a biomarker for environmental benzene exposure is feasible since it was detectable in 72% of subjects with a wide range of values present. In future studies, correlation of MA with personal air sampling in environmental exposure will be essential to fully interpret the significance of these findings. In addition, these inner-city children comprise a high risk group for exposure to environmental toxicants including ETS, lead, and probably benzene, based on questionnaire sources and its presence in ETS. Images Figure 1. Figure 2. Figure 3. Figure 4. Figure 4. Figure 5. PMID:8919771

  20. Folic acid - vitamin and panacea or genetic time bomb?

    PubMed

    Lucock, Mark; Yates, Zoë

    2005-03-01

    We live in a health-conscious age - many of us supplement our diet with essential micronutrients through the discretionary use of multivitamin pills or judicious selection of foods that have a health benefit beyond that conferred by the nutrient content alone - the so-called 'functional foods'. Indeed, the citizens of some nations have little choice, with a mandatory fortification policy in place for certain vitamins. But do we ever stop to consider the consequences of an increased exposure to micronutrients? We examine this issue in relation to the B-group vitamin folic acid, and ask whether supplementation with this vitamin could introduce a strong genetic selection pressure - one that has the side effect of increasing the prevalence of some of the most significant, human life-threatening diseases. Are we affecting our genetics - is this a case of human evolution in progress by altering our diet?

  1. Clinical and histopathological changes of the nasal mucosa induced by occupational exposure to sulphuric acid mists

    PubMed Central

    Grasel, S; Alves, V; da Silva, C S; Cruz, O; Almeida, E; de Oliveira, E

    2003-01-01

    Aims: To assess potential alterations of the nasal mucosa by clinical and histopathological evaluation of workers exposed to sulphuric acid mists at anodising plants, correlating the findings with duration of exposure and sulphuric acid concentrations in the air, and comparing them with a control group. Methods: Fifty two workers from five plants underwent a clinical evaluation (standard questionnaire, clinical, and ear, nose, and throat examination including nasal endoscopy). For the histopathological study, 20 of the 52 subjects (study group) were randomly selected, as well as 11 unexposed subjects (control group), matched by sex, age, and smoking habits. Nasal biopsy specimens were obtained from the anterior septum mucosa and the anterior curvature of the middle turbinate in each individual. A total of 56 nasal mucosa specimens (37 in the study group and 19 in the control group) were evaluated with regard to normal respiratory epithelium or metaplastic epithelium, atypia or dysplasia, and alterations of the lamina propria. Results: The histopathological study revealed squamous metaplasia in 29 (79%) and atypia in 13 (35%) of the 37 study group samples. No association was found between exposure duration and the clinical and histopathological variables, but a significant association was found between sulphuric acid concentrations higher than 200 µg/m3 and pale mucosal patches and ulcerations in the exposed subjects. Logistic regression analysis showed that the exposed subjects had a fivefold risk of developing atypia compared with the unexposed subjects. Conclusions: Workers exposed to sulphuric acid mists presented with a high incidence of nasal symptoms, and macroscopic and microscopic changes of the nasal mucosa, including squamous atypia and dysplasia. The risk for these histopthological lesions increased with higher sulphuric acid concentrations in the air, revealing an exposure-response relation. PMID:12771390

  2. Water age, exposure time, and local flushing time in semi-enclosed, tidal basins with negligible freshwater inflow

    NASA Astrophysics Data System (ADS)

    Viero, Daniele Pietro; Defina, Andrea

    2016-04-01

    Within the framework of tidally flushed, semi-enclosed basins with negligible freshwater inflow, and under steady periodic flow conditions, three frequently used local transport time scales to quantify the efficiency of water renewal, namely water age, exposure time, and local flushing time are studied and compared to each other. In these environments, water renewal is strongly controlled by diffusion, and it is significantly affected by the return flow (i.e., the fraction of effluent water that returns into the basin on each flood tide). The definition of water age is here modified to account for the return flow, in analogy with exposure time and local flushing time. We consider approximate time scales, whose accuracy is analyzed, in order to overcome problems related to the size of the computational domain and to reduce the computational effort. A new approximate procedure is introduced to estimate water age, which is based on the water aging rate. Also, the concept of local flushing time as a relevant time scale is introduced. Under steady periodic conditions, we demonstrate that the local flushing time quantitatively corresponds to water age, and well approximates exposure time when the flow is dominated by diffusion. Since the effort required to compute water age and exposure time is greater than that required to compute the local flushing time, the present results can also have a practical interest in the assessment of water renewal efficiency of semi-enclosed water basins. The results of a modeling study, in which the lagoon of Venice is used as a benchmark, confirm the substantial quantitative equivalence between these three transport time scales in highly diffusive environments.

  3. Malignant lymphoma and exposure to chemicals, especially organic solvents, chlorophenols and phenoxy acids: a case-control study.

    PubMed Central

    Hardell, L.; Eriksson, M.; Lenner, P.; Lundgren, E.

    1981-01-01

    A number of men with malignant lymphoma of the histiocytic type and previous exposure to phenoxy acids or chlorophenols were observed and reported in 1979. A matched case-control study has therefore been performed with cases of malignant lymphoma (Hodgkin's disease and non-Hodgkin lymphoma). This study included 169 cases and 338 controls. The results indicate that exposure to phenoxy acids, chlorophenols, and organic solvents may be a causative factor in malignant lymphoma. Combined exposure of these chemicals seemed to increase the risk. Exposure to various other agents was not obviously different in cases and in controls. PMID:7470379

  4. Dermal absorption and skin damage following hydrofluoric acid exposure in an ex vivo human skin model.

    PubMed

    Dennerlein, Kathrin; Kiesewetter, Franklin; Kilo, Sonja; Jäger, Thomas; Göen, Thomas; Korinth, Gintautas; Drexler, Hans

    2016-04-25

    The wide industrial use of hydrofluoric acid (HF) poses a high risk for accidental dermal exposure. Despite local and systemic hazards associated with HF, information on percutaneous penetration and tissue damage is rare. In the present ex vivo study, the dermal absorption of HF (detected in terms of fluoride ions) was quantified and the skin damaging potential as a function of concentration and exposure duration was assessed. Percutaneous penetration of HF (c=5, 30, and 50%) at 3 exposure durations (3, 5, and 10 min) was investigated in a static diffusion cell model using freshly excised human skin. Alterations of skin were histologically evaluated. HF rapidly penetrated through skin under formation of a considerable intradermal reservoir (∼ 13-67% of total absorbed fluoride). Histologically, epidermal alterations were detected already after exposure to 5% HF for 3 min. The degree of skin damage increased with rising concentration and exposure duration leading to coagulation necrosis. For HF concentrations of ≥ 30%, skin damage progressed into deeper skin layers. Topically applied HF concentration was the principal parameter determining HF induced skin effects. The intradermal HF retention capacity associated with progression and prolongation of HF induced skin effects must be considered in the review of skin decontamination procedures.

  5. Human environmental and occupational exposures to boric acid: reconciliation with experimental reproductive toxicity data.

    PubMed

    Bolt, Hermann M; Başaran, Nurşen; Duydu, Yalçın

    2012-01-01

    The reproductive toxicity of boric acid and borates is a matter of current regulatory concern. Based on experimental studies in rats, no-observed-adverse-effect levels (NOAELs) were found to be 17.5 mg boron (B)/kg body weight (b.w.) for male fertility and 9.6 mg B/kg b.w. for developmental toxicity. Recently, occupational human field studies in highly exposed cohorts were reported from China and Turkey, with both studies showing negative results regarding male reproduction. A comparison of the conditions of these studies with the experimental NOAEL conditions are based on reported B blood levels, which is clearly superior to a scaling according to estimated B exposures. A comparison of estimated daily B exposure levels and measured B blood levels confirms the preference of biomonitoring data for a comparison of human field studies. In general, it appears that high environmental exposures to B are lower than possible high occupational exposures. The comparison reveals no contradiction between human and experimental reproductive toxicity data. It clearly appears that human B exposures, even in the highest exposed cohorts, are too low to reach the blood (and target tissue) concentrations that would be required to exert adverse effects on reproductive functions.

  6. Molecular-biological analysis of acute lung injury (ALI) induced by heat exposure and/or intravenous administration of oleic acid.

    PubMed

    Inoue, Hiromasa; Nakagawa, Yasuhisa; Ikemura, Mayumi; Usugi, Eri; Nata, Masayuki

    2012-11-01

    The aim of this study was to molecular-biologically investigate the interaction between heat exposure and pulmonary fat embolization in regards to the development of acute lung injury (ALI). Ten-week-old Wistar male rats were divided into four groups: (1) oleic acid injected into caudal vein after heat exposure, (2) oleic acid injected without heat exposure, (3) soybean oil injected after heat exposure, and (4) soybean oil injected without heat exposure, and then mRNA expression of eight inflammatory mediators related to ALI/acute respiratory distress syndrome (ARDS) and heat shock protein 70 (Hsp70) in lung was determined 1h after the injection. mRNA expression of interleukin 1 beta (Il1b), tumor necrosis factor alpha (Tnfa), vascular endothelial growth factor A (Vegfa), transforming growth factor beta 1 (Tgfb1) and Hsp70 was significantly increased by heat exposure, while that of Il1b, interleukin 6 (Il6), Tnfa, macrophage inflammatory protein 2 (Mip2) and granulocyte macrophage-colony stimulating factor (Gm-csf) was significantly elevated by the injection of oleic acid. Moreover, the expressions of inflammatory cytokines and chemokines in lung almost paralleled their mRNA expressions. In particular, IL-1β expression was synergistically elevated by heat exposure followed by injection of oleic acid. Additionally, IL-6 expression tended to increase under the same conditions as well. It is likely that heat exposure itself injures lung tissue within a short time, and that more than two conditions which induce ALI/ARDS interact with each other synergistically, exacerbating the development of ALI/ARDS.

  7. Repeated exposure of acidic beverages on esthetic restorative materials: An in-vitro surface microhardness study

    PubMed Central

    Sunny, Steffy M.; Rai, Kavita; Hegde, Amitha M.

    2016-01-01

    Background A manifold increase in the consumption of aerated beverages has witnessed a twin increase in tooth wear and raised demand for esthetic restorative materials. This study aimed to evaluate the surface microhardness changes of esthetic restorative materials following treatment with aerated beverages in an in-vitro situation. Material and Methods The initial surface microhardness of the restorative materials GC Fuji II LC, GC Fuji IX, Nano Glass ionomer, Resin and Nano composite was recorded. These materials were studied under 3 groups that included those exposed to the acidic beverages daily, weekly once in a month and those that had no exposures at all. The final surface microhardness of the materials was recorded following experimentation and was subjected to statistical comparisons. Results The restorative materials were compared for their surface microhardness changes following respective treatments using the T-test and One-way ANOVA analysis. Inter-comparisons between the groups showed statistical significance (p<.05), when treated with both the beverages. The five restorative materials revealed surface microhardness loss; the maximum reduction noticed with the Nano glass ionomer cement tested (p<.0005). Conclusions The surface microhardness of restorative materials markedly reduced upon repeated exposures with acidic beverages; the product with phosphoric acid producing the maximum surface microhardness loss. Key words:Restorative materials, acidic beverages, surface microhardness, resin composites, glass ionomers. PMID:27398183

  8. Ascorbic acid abrogates microparticle generation and vascular injuries associated with high-pressure exposure.

    PubMed

    Yang, Ming; Bhopale, Veena M; Thom, Stephen R

    2015-07-01

    We hypothesized that pathological changes associated with elevations in annexin V-positive microparticles (MPs) following high-pressure exposures can be abrogated by ascorbic acid in a murine model. Mice exposed for 2 h to 790-kPa air and killed at 2 or 13 h postdecompression exhibited over threefold elevations in circulating MPs, as well as subgroups bearing Ly6G, CD41, Ter119, CD31, and CD142 surface proteins. There was evidence of significant neutrophil activation, platelet-neutrophil interactions, and vascular injury to brain, omentum, psoas, and skeletal muscles assessed as leakage of high-molecular-weight dextran. Prophylactic ascorbic acid (500 mg/kg ip) administration prevented all postdecompression neutrophil changes and vascular injuries. Ascorbic acid administration immediately after decompression abrogated most changes, but evidence of vascular leakage in the brain and skeletal muscle at 13 h postdecompression persisted. No significant elevations in these parameters occurred after injection of ascorbic acid alone. The findings support the idea that MP production occurring with exposures to elevated gas pressure is an oxidative stress response and that antioxidants may offer protection from pathological effects associated with decompression. PMID:25977448

  9. Arsenate exposure affects amino acids, mineral nutrient status and antioxidants in rice (Oryza sativa L.) genotypes.

    PubMed

    Dwivedi, S; Tripathi, R D; Tripathi, P; Kumar, A; Dave, R; Mishra, S; Singh, R; Sharma, D; Rai, U N; Chakrabarty, D; Trivedi, P K; Adhikari, B; Bag, M K; Dhankher, O P; Tuli, R

    2010-12-15

    Simulated pot experiments were conducted on four rice (Oryza sativa L.) genotypes (Triguna, IR-36, PNR-519, and IET-4786) to examine the effects of As(V) on amino acids and mineral nutrient status in grain along with antioxidant response to arsenic exposure. Rice genotypes responded differentially to As(V) exposure in terms of amino acids and antioxidant profiles. Total amino acid content in grains of all rice genotypes was positively correlated with arsenic accumulation. While, most of the essential amino acids increased in all cultivars except IR-36, glutamic acid and glycine increased in IET-4786 and PNR-519. The level of nonprotein thiols (NPTs) and the activities of superoxide dismutase (SOD; EC 1.15.1.1), glutathione reductase (GR; EC 1.6.4.2) and ascorbate peroxidase (APX; EC 1.11.1.11) increased in all rice cultivars except IET-4786. A significant genotypic variation was also observed in specific arsenic uptake (SAU; mg kg(-1)dw), which was in the order of Triguna (134) > IR-36 (71) > PNR-519 (53) > IET-4786 (29). Further, application of As(V) at lower doses (4 and 8 mg L(-1) As) enhanced the accumulation of selenium (Se) and other nutrients (Fe, P, Zn, and S), however, higher dose (12 mg L(-1) As) limits the nutrient uptake in rice. In conclusion, low As accumulating genotype, IET-4786, which also had significantly induced level of essential amino acids, seems suitable for cultivation in moderately As contaminated soil and would be safe for human consumption. PMID:21077666

  10. Comparative responses of freshwater organisms to exposures of a commercial naphthenic acid.

    PubMed

    Kinley, Ciera M; McQueen, Andrew D; Rodgers, John H

    2016-06-01

    Comparative toxicity studies using unconfounded exposures can prioritize the selection of sensitive sentinel test species and refine methods for evaluating ecological risks of complex mixtures like naphthenic acids (NAs), a group of organic acids associated with crude oils and energy-derived waters that have been a source of aquatic toxicity. The objectives of this study were to compare responses of freshwater aquatic organisms (vertebrate, invertebrates, and a macrophyte; in terms of acute toxicity) to Fluka commercial NAs and to compare measured toxicity data with peer-reviewed toxicity data for other commercial NA sources and energy-derived NA sources. Exposures were confirmed using high performance liquid chromatography. Responses (7-d LC50s/EC50) ranged from 1.9 mg L(-1) for Pimephales promelas to 56.2 mg L(-1) for Typha latifolia. Following P. promelas in order of decreasing sensitivity were Ceriodaphnia dubia (7-d LC50 = 2.8 mg L(-1)), Hyalella azteca (7-d LC50 = 4.1 mg L(-1)), Chironomus dilutus (7-d LC50 = 6.5 mg L(-1)), and T. latifolia (7-d EC50 = 56.2 mg L(-1)), indicating that in terms of sensitivities, fish > invertebrates > plant for Fluka NAs in this study. Factors that affect exposures and measurements of exposures differ among commercial and energy-derived NAs and constrain comparisons. Despite differences in exposures, fish and invertebrates were relatively sensitive to both commercial and energy-derived NA sources (based on laboratory measurements and peer-reviewed data) and could be appropriate sentinel species for risk evaluations. PMID:27016812

  11. Unifying susceptibility, exposure, and time: discussion of unifying analytic approaches and future directions.

    PubMed

    Künzli, Nino

    This article reviews design and analysis concepts associated with the following major issues in air pollution epidemiology: (1) time-related determinants of health effects, including duration of exposure and disentangling acute effects and total life-shortening associated with long-term exposure; and (2) the role of geographies of susceptibility and exposure including the relevance and impact of ecologic covariates in the assessment of long-term effects of ambient air pollution. The article identifies the potential contribution associated with improved information in these areas to air pollution policy development and argues that these issues should frame future approaches to assessing the total effects of ambient air pollution.

  12. Time reducing exposure containing 18 fluorine flourodeoxyglucose master vial dispensing in hot lab: Omega technique

    PubMed Central

    Rao, Vatturi Venkata Satya Prabhakar; Manthri, Ranadheer; Hemalatha, Pottumuthu; Kumar, Vuyyuru Navin; Azhar, Mohammad

    2016-01-01

    Hot lab dispensing of large doses of 18 fluorine fluorodeoxyglucose in master vials supplied from the cyclotrons requires high degrees of skill to handle high doses. Presently practiced conventional method of fractionating from the inverted tiltable vial pig mounted on a metal frame has its own limitations such as increasing isotope handling times and exposure to the technologist. Innovative technique devised markedly improves the fractionating efficiency along with speed, precision, and reduced dose exposure. PMID:27095872

  13. Firefighters' exposure to perfluoroalkyl acids and 2-butoxyethanol present in firefighting foams.

    PubMed

    Laitinen, Juha Ari; Koponen, Jani; Koikkalainen, Janne; Kiviranta, Hannu

    2014-12-01

    The aim of this study was to assess eight firefighters' exposure to Sthamex 3% AFFF (aqueous film forming foam) in the simulation of aircraft accidents at Oulu airport in Finland. Study was conducted in 2010 before limitation for the use of PFOA and PFOS in AFFFs. Due to prospective limitation also eight commercially available AFFFs were evaluated from occupational and environmental point of view to find substitutive AFFFs for future. The firefighters' exposure to twelve perfluoroalkyl acids (PFAS) was analyzed in order to observe the signs of accumulation during three consecutive training sessions. The firefighters' short-term exposure to 2-butoxyethanol (EGBE) was analyzed by urinalysis of 2-butoxyacetic acid (2-BAA). For the background information also the concentration of PFAS in used AFFF-liquid was analyzed. Fire fighters' serum PFHxS and PFNA concentrations seemed to increase during the three training sessions although they were not the main PFAS in used AFFF. The statistical significance for the elevations was not able to test due to limited size of test group. In two training sessions, the average urinary excretions of 2-BAA exceeded the reference limit of the occupationally unexposed population. In the evaluations of the firefighting foams, non-fluorine based products were favored and the alcohol resistance properties of foams were recommended for consideration due to the increasing use of biofuels.

  14. Firefighters' exposure to perfluoroalkyl acids and 2-butoxyethanol present in firefighting foams.

    PubMed

    Laitinen, Juha Ari; Koponen, Jani; Koikkalainen, Janne; Kiviranta, Hannu

    2014-12-01

    The aim of this study was to assess eight firefighters' exposure to Sthamex 3% AFFF (aqueous film forming foam) in the simulation of aircraft accidents at Oulu airport in Finland. Study was conducted in 2010 before limitation for the use of PFOA and PFOS in AFFFs. Due to prospective limitation also eight commercially available AFFFs were evaluated from occupational and environmental point of view to find substitutive AFFFs for future. The firefighters' exposure to twelve perfluoroalkyl acids (PFAS) was analyzed in order to observe the signs of accumulation during three consecutive training sessions. The firefighters' short-term exposure to 2-butoxyethanol (EGBE) was analyzed by urinalysis of 2-butoxyacetic acid (2-BAA). For the background information also the concentration of PFAS in used AFFF-liquid was analyzed. Fire fighters' serum PFHxS and PFNA concentrations seemed to increase during the three training sessions although they were not the main PFAS in used AFFF. The statistical significance for the elevations was not able to test due to limited size of test group. In two training sessions, the average urinary excretions of 2-BAA exceeded the reference limit of the occupationally unexposed population. In the evaluations of the firefighting foams, non-fluorine based products were favored and the alcohol resistance properties of foams were recommended for consideration due to the increasing use of biofuels. PMID:25447453

  15. Research plan for establishing the effects of time varying noise exposures on community annoyance and acceptability

    NASA Technical Reports Server (NTRS)

    Borsky, P. N.

    1980-01-01

    The design of a community noise survey to determine the effects of time varying noise exposures in residential communities is presented. Complex physical and human variables involved in the health and welfare effects of environmental noise and the number-level tradeoffs and time of day penalties are among the factors considered. Emphasis is placed on community reactions where noise exposures are equal in day or evening but differ in the night time, and the effects of ambient noise on more intense aircraft noise exposures. Thirteen different times of day and types of operation situations with exposed populations up to 8-10 miles from the airport are identified. A detailed personal interview questionnaire as well as specific instructions to interviewers are included.

  16. Retrospective Exposure Estimation and Predicted versus Observed Serum Perfluorooctanoic Acid Concentrations for Participants in the C8 Health Project

    PubMed Central

    Vieira, Verónica M.; Ryan, P. Barry; Steenland, Kyle; Bartell, Scott M.

    2011-01-01

    Background: People living or working in eastern Ohio and western West Virginia have been exposed to perfluorooctanoic acid (PFOA) released by DuPont Washington Works facilities. Objectives: Our objective was to estimate historical PFOA exposures and serum concentrations experienced by 45,276 non-occupationally exposed participants in the C8 Health Project who consented to share their residential histories and a 2005–2006 serum PFOA measurement. Methods: We estimated annual PFOA exposure rates for each individual based on predicted calibrated water concentrations and predicted air concentrations using an environmental fate and transport model, individual residential histories, and maps of public water supply networks. We coupled individual exposure estimates with a one-compartment absorption, distribution, metabolism, and excretion (ADME) model to estimate time-dependent serum concentrations. Results: For all participants (n = 45,276), predicted and observed median serum concentrations in 2005–2006 are 14.2 and 24.3 ppb, respectively [Spearman’s rank correlation coefficient (rs) = 0.67]. For participants who provided daily public well water consumption rate and who had the same residence and workplace in one of six municipal water districts for 5 years before the serum sample (n = 1,074), predicted and observed median serum concentrations in 2005–2006 are 32.2 and 40.0 ppb, respectively (rs = 0.82). Conclusions: Serum PFOA concentrations predicted by linked exposure and ADME models correlated well with observed 2005–2006 human serum concentrations for C8 Health Project participants. These individualized retrospective exposure and serum estimates are being used in a variety of epidemiologic studies being conducted in this region. PMID:21813367

  17. Long term exposure to respirable volcanic ash on Montserrat: a time series simulation

    NASA Astrophysics Data System (ADS)

    Hincks, T. K.; Aspinall, W. P.; Baxter, P. J.; Searl, A.; Sparks, R. S. J.; Woo, G.

    2006-01-01

    Frequent ash fallout from long-lived eruptions (with active phases greater than 5 years) may lead to local populations experiencing unacceptably high cumulative exposures to respirable particulate matter. Ash from Montserrat has been shown to contain significant levels of cristobalite and other reactive agents that are associated with an increased risk of developing pneumoconiosis (including silicosis) and other long-term health problems. There are a number of difficulties associated with estimating risks in populations due to uncertain and wide ranging individual exposures, change in behaviour with time and the natural variation in individual response. Present estimates of risk in workers and other population groups are simplifications based on a limited number of exposure measurements taken on Montserrat (1996-1999), and exposure-response curves from epidemiological studies of coal workers exposed to siliceous dust. In this paper we present a method for calculating the long-term cumulative exposure to cristobalite from volcanic ash by Monte Carlo simulation. Code has been written to generate synthetic time series for volcanic activity, rainfall, ash deposition and erosion to give daily ash deposit values and cristobalite fraction at a range of locations. The daily mean personal exposure for PM10 and cristobalite is obtained by sampling from a probability distribution, with distribution parameters dependent on occupation, ground deposit depth and daily weather conditions. Output from multiple runs is processed to calculate the exceedance probability for cumulative exposure over a range of occupation types, locations and exposure periods. Results are interpreted in terms of current occupational standards, and epidemiological exposure-response functions for silicosis are applied to quantify the long-term health risk. Assuming continuing volcanic activity, median risk of silicosis (profusion 1/0 or higher) for an average adult after 20 years continuous exposure is

  18. Radiofrequency exposure in the French general population: band, time, location and activity variability.

    PubMed

    Viel, Jean-François; Cardis, Elisabeth; Moissonnier, Monika; de Seze, René; Hours, Martine

    2009-11-01

    Information on the exposure of individual persons to radiofrequency (RF) fields is scarce, although such data are crucial in order to develop a suitable exposure assessment method, and frame the hypothesis and design of future epidemiological studies. The main goal of this survey is to assess individual RF exposure on a population basis, while clarifying the relative contribution of different sources to the total exposure. A total of 377 randomly selected people were analyzed. Each participant was supplied with a personal exposure meter for 24-hour measurements (weekday), and kept a time-location-activity diary. Electric field strengths were recorded in 12 different RF bands every 13s. Summary statistics were calculated with the robust regression on order statistics method. Most of the time, recorded field strengths were not detectable with the exposure meter. Total field, cordless phones, WiFi-microwave, and FM transmitters stood apart with a proportion above the detection threshold of 46.6%, 17.2%, 14.1%, and 11.0%, respectively. The total field mean value was 0.201V/m, higher in urban areas, during daytime, among adults, and when moving. When focusing on specific channels, the highest mean exposure resulted from FM sources (0.044V/m), followed by WiFi-microwaves (0.038V/m), cordless phones (0.037V/m), and mobile phones (UMTS: 0.036V/m, UMTS: 0.037V/m). Various factors, however, contributed to a high variability in RF exposure assessment. These population-based estimates should therefore be confirmed by further surveys to better characterize the exposure situation in different microenvironments.

  19. Investigating the American Time Use Survey from an Exposure Modeling Perspective

    EPA Science Inventory

    This paper describes an evaluation of the U.S. Bureau of Labor Statistics' American Time Use Survey (ATUS) for potential use in modeling human exposures to environmental pollutants. The ATUS is a large, on-going, cross-sectional survey of where Americans spend time and what activ...

  20. Statistical Properties of Longitudinal Time-Activity Data for Use in Human Exposure Modeling

    EPA Science Inventory

    Understanding the longitudinal properties of the time spent in different locations and activities is important in characterizing human exposure to pollutants. The results of a four-season longitudinal time-activity diary study in eight working adults are presented, with the goal ...

  1. Aristolochic acid exposure in Romania and implications for renal cell carcinoma

    PubMed Central

    Turesky, Robert J; Yun, Byeong Hwa; Brennan, Paul; Mates, Dana; Jinga, Viorel; Harnden, Patricia; Banks, Rosamonde E; Blanche, Helene; Bihoreau, Marie-Therese; Chopard, Priscilia; Letourneau, Louis; Lathrop, G Mark; Scelo, Ghislaine

    2016-01-01

    Background: Aristolochic acid (AA) is a nephrotoxicant associated with AA nephropathy (AAN) and upper urothelial tract cancer (UUTC). Whole-genome sequences of 14 Romanian cases of renal cell carcinoma (RCC) recently exhibited mutational signatures consistent with AA exposure, although RCC had not been previously linked with AAN and AA exposure was previously reported only in localised rural areas. Methods: We performed mass spectrometric measurements of the aristolactam (AL) DNA adduct 7-(deoxyadenosin-N6-yl) aristolactam I (dA-AL-I) in nontumour renal tissues of the 14 Romanian RCC cases and 15 cases from 3 other countries. Results: We detected dA-AL-I in the 14 Romanian cases at levels ranging from 0.7 to 27 adducts per 108 DNA bases, in line with levels reported in Asian and Balkan populations exposed through herbal remedies or food contamination. The 15 cases from other countries were negative. Interpretation: Although the source of exposure is uncertain and likely different in AAN regions than elsewhere, our results demonstrate that AA exposure in Romania exists outside localised AAN regions and provide further evidence implicating AA in RCC. PMID:26657656

  2. Prenatal valproic acid exposure disrupts tonotopic c-Fos expression in the rat brainstem.

    PubMed

    Dubiel, A; Kulesza, R J

    2016-06-01

    Autism spectrum disorder (ASD) is a group of neurodevelopmental conditions characterized by difficulties in communication and social interactions, restricted, repetitive behaviors and sensory abnormalities. Notably, the vast majority of individuals with ASD experience some degree of auditory dysfunction and we have recently reported consistent hypoplasia and dysmorphology in auditory brainstem centers in individuals with ASD. Prenatal exposure to the antiepileptic drug valproic acid (VPA) is associated with an increased risk of ASD. In rodents, prenatal exposure to VPA is employed as an animal model of ASD and is associated with a number of anatomical, physiological and behavioral deficits, including hypoplasia and dysmorphology of auditory brainstem centers. Based on these observations, we hypothesized that such dysmorphology in VPA-exposed animals would translate into abnormal neuronal activity in brainstem circuits and irregular tonotopic maps. Herein, we have subjected control and VPA-exposed animals to 4- or 16-kHz tones and examined neuronal activation with immunohistochemistry for c-Fos. After these exposures, we identified significantly more c-Fos-positive neurons in the auditory brainstem of VPA-exposed animals. Additionally, we observed a larger dispersion of c-Fos-positive neurons and shifted tonotopic bands in VPA-exposed rats. We interpret these findings to suggest hyper-responsiveness to sounds and disrupted mapping of sound frequencies after prenatal VPA exposure. Based on these findings, we suggest that such abnormal patterns of activation may play a role in auditory processing deficits in ASD. PMID:27094734

  3. Growth response of Pinus ponderosa seedlings and mature tree branches to acid rain and ozone exposure

    SciTech Connect

    Anderson, P.D.; Houpis, J.L.J.; Helms, J.A.

    1994-10-01

    Forests of the central and southern Sierra Nevada in California have been subjected to chronic damage by ozone and other atmospheric pollutants for the past several decades. Until recently, pollutant exposure of northern Sierra Nevada forests has been mild but increasing population and changes in land use throughout the Sacramento Valley and Sierra Nevada foothills may lead to increased pollutant damage in these forests. Although, better documented in other regions of the United States, little is known regarding the potential for acidic precipitation damage to Sierra Nevada forests. Only recently have studies directed towards understanding the potential interactive effects of ozone and acidic precipitation been undertaken. A key issue in resolving potential regional impacts of pollutants on forests is the extent to which research results can be scaled across genotypes and life-stages. Most of the pollution research to date has been performed using seedlings with varying degrees of genetic control. It is important to determine if the results obtained in such studies can be extrapolated to mature trees and to different genetic sources. In this paper, we present results from a one-year study examining the interactive effects of foliar exposure to acidic rain and ozone on the growth of ponderosa pine (Pinus ponderosa), a conifer known to be sensitive to ozone. The response to pollutants is characterized for both seedlings and mature tree branches of three genotypes grown in a common environment.

  4. Estimates of the occupational exposure to tenorm in the phosphoric acid production plant in Iran.

    PubMed

    Fathabadi, N; Vasheghani Farahani, M; Moradi, M; Hadadi, B

    2012-09-01

    Phosphate rock is used world wide for manufacturing phosphoric acid and several chemical fertilisers. It is known that the phosphate rock contains various concentrations of uranium, thorium, radium and their daughters. The subject of this study is the evaluation of the radiation exposure to workers in the phosphoric acid production plant due to technologically enhanced naturally occurring radioactive materials that can result from the presence of naturally occurring radioactive materials in phosphate ores used in the manufacturing of phosphoric acid. Radiation exposure due to direct gamma radiation, dust inhalation and radon gas has been investigated and external and internal doses of exposed workers have been calculated. Natural radioactivity due to (40)K, (226)Ra and (232)Th have been measured in phosphate rock, phosphogypsum, chemical fertilisers and other samples by gamma spectrometry system with a high-purity germanium. The average concentrations of (226)Ra and (40)K observed in the phosphate rock are 760 and 80 Bq kg(-1), respectively. Annual effective dose from external radiation had a mean value of ∼0.673 mSv y(-1). Dust sampling revealed greatest values in the storage area. The annual average effective dose from inhalation of long-lived airborne was 0.113 mSv y(-1). Radon gas concentrations in the processing plant and storage area were found to be of the same value as the background. In this study the estimated annual effective doses to workers were below 1 mSv y(-1). PMID:22361352

  5. [Real time PCR methodology for quantification of nucleic acids].

    PubMed

    Tse, C; Capeau, J

    2003-01-01

    The polymerase chain reaction (PCR) has become an essential tool for molecular biologists and its introduction into nucleic acids detection systems has revolutionized the quantitative analysis of DNA and RNA. The technique has rapidly evolved over the last few years and the growing interest in quantitative applications of the PCR has favoured the development of real-time quantitative PCR. In this paper, we review, after presentation of the theorical aspects of PCR, the basic principles of real-time PCR with the introduction of the concept of threshold cycle. More precisely, we describe the novel assay formats that greatly simplify the protocols used for the detection of specific nucleic acids. We focus on the actual four technologies that enable sequence detection in a closed tube and that are SYBR Green I, TaqMan probes, Hybridization probes and Molecular Beacon probes. We then discuss the different quantification strategies in real time PCR and compare the competiting instruments on the market. The most important real-time PCR applications in clinical biology are also described.

  6. Exposure or release of ferulic acid from wheat aleurone: impact on its antioxidant capacity.

    PubMed

    Rosa, Natalia N; Dufour, Claire; Lullien-Pellerin, Valérie; Micard, Valérie

    2013-12-01

    The relationship between the aleurone cell integrity and the exposure or release of bioavailable ferulic acid (FA) with the antioxidant capacity of aleurone in in vitro and under simulated gastric conditions was explored. The antioxidant capacity of aleurone was increased by around 2-fold when its median particle size was reduced to under 50 μm. The opening of aleurone cells increased the physical exposure of FA bound to the insoluble polysaccharides, which seemed to be responsible of the increased antioxidant capacity. Synergistic combination of xylanase and feruloyl esterase was found to be the most efficient enzymatic treatment releasing up to 86% of total FA in bioaccessible forms. This enzymatic treatment significantly enhanced the radical scavenging activity of aleurone by up to 4-fold, which overlapped the overall antioxidant potential estimated from the total content of FA in aleurone. The improvement in the antioxidant capacity of aleurone was also observed in the simulated gastric digestion by inhibition of lipid oxidation.

  7. The effect of ultrasonic irrigation before and after citric acid treatment on collagen fibril exposure: an in vitro SEM study.

    PubMed

    Higashi, T; Okamoto, H

    1995-10-01

    The surface characteristics of periodontally diseased human teeth after two treatments were compared both before and after partial demineralization with citric acid. Thirteen teeth were obtained from patients with advanced periodontal disease. Three teeth were selected for control groups and 10 were used for experimental groups. All diseased root surfaces were identified and outlined. The roots were cut longitudinally into two sections. They were then scaled and root planed and the paired sections were separately classified into two control or two experimental groups. Three sections in control group 1 were rinsed by syringe with saline solution. The three sections in control group 2 were treated with ultrasonic irrigation. The 10 sections in experimental group 1 were rinsed by syringe with saline solution before and after citric acid application; the 10 sections in experimental group 2 were irrigated ultrasonically before and after citric acid application. The concentration of the citric acid was 25% (pH 1.62) and the immersion time was 3 minutes. The root samples were examined by scanning electron microscope. A significant amount of grinding debris covered on all the root surfaces in control group 1, whereas smear was removed in control group 2. The features of root surfaces of the two experimental groups differed considerably. All specimens in experimental group 2 exhibited collagen fibrils exposed as a consequence of citric acid etching. On the other hand, the smear layer was not thoroughly removed from the root surface in experimental group 1, which meant that few collagen fibrils were exposed after partial demineralization. From these results, ultrasonic irrigation before and after citric acid application improves exposure of collagen fibrils, which may be desirable for clinical success in periodontal regenerative therapy.

  8. Acute exposure to realistic acid fog: effects on respiratory function and airway responsiveness in asthmatics.

    PubMed

    Leduc, D; Fally, S; De Vuyst, P; Wollast, R; Yernault, J C

    1995-11-01

    Naturally occurring fogs in industrialized cities are contaminated by acidic air pollutants. In Brussels, Belgium, the pH of polluted fogwater may be as low as 3 with osmolarity as low as 30 mOsm. In order to explore short-term respiratory effects of a realistic acid-polluted fog, we collected samples of acid fog in Brussels, Belgium, which is a densely populated and industrialized city, we defined characteristics of this fog and exposed asthmatic volunteers at rest through a face mask to fogs with physical and chemical characteristics similar to those of natural fogs assessed in this urban area. Fogwater was sampled using a screen collector where droplets are collected by inertial impaction and chemical content of fogwater was assessed by measurement of conductivity, pH, visible colorimetry, high pressure liquid chromatography, and atomic absorption spectrophotometry over a period of one year. The fogwater composition was dominated by NH4+ and SO4- ions. First we evaluated the possible effect of fog acidity alone. For this purpose 14 subjects with asthma were exposed at rest for 1 hr [mass median aerodynamic diameter to a large-particle (MMAD), 9 microns] aerosol with H2SO4 concentration of 500 micrograms/m3 (pH 2.5) and osmolarity of 300 mOsm. We did not observe significant change in pulmonary function or bronchial responsiveness to metacholine. In the second part of the work, 10 asthmatic subjects were exposed to acid fog (MMAD, 7 microns) containing sulfate and ammonium ions (major ions recovered in naturally occurring fogs) with pH 3.5 and osmolarity 30 mOsm. Again, pulmonary function and bronchial reactivity were not modified after inhalation of this fog. It was concluded that short-term exposure to acid fog reproducing acidity and hypoosmolarity of natural polluted fogs does not induce bronchoconstriction and does not change bronchial responsiveness in asthmatics.

  9. Highly time-variable exposure to chemicals--toward an assessment strategy.

    PubMed

    Ashauer, Roman; Brown, Colin D

    2013-07-01

    Organisms in the environment experience fluctuating, pulsed, or intermittent exposure to pollutants. Accounting for effects of such exposures is an important challenge for environmental risk assessment, particularly given the simplified design of standard ecotoxicity tests. Dynamic simulation using toxicokinetic-toxicodynamic (TK-TD) models describes the processes that link exposure with effects in an organism and provides a basis for extrapolation to a range of exposure scenarios. In so doing, TK-TD modeling makes the risk assessment more robust and aids use and interpretation of experimental data. Toxicokinetic-toxicodynamic models are well-developed for predicting survival of individual organisms and are increasingly applied to sublethal endpoints. In the latter case particularly, linkage to individual-based models (IBMs) allows extrapolation to population level as well as accounting for differences in effects of toxicant exposure at different stages in the life cycle. Extrapolation between species remains an important constraint because there is currently no systematic understanding of species traits that cause differences in the relevant processes. Toxicokinetic-toxicodynamic models allow interrogation of exposure profiles to determine intrinsic toxicity potential rather than using absolute maximum concentrations or time-weighted averages as surrogates. A decision scheme is proposed to guide selection of risk assessment approaches using dose extrapolation based on Haber's Law, TK-TD models, and/or IBMs depending on the nature of toxic effect and timing in relation to life history. PMID:23564608

  10. Distinct neurobehavioral dysfunction based on the timing of developmental binge-like alcohol exposure.

    PubMed

    Sadrian, B; Lopez-Guzman, M; Wilson, D A; Saito, M

    2014-11-01

    Gestational exposure to alcohol can result in long-lasting behavioral deficiencies generally described as fetal alcohol spectrum disorder (FASD). FASD-modeled rodent studies of acute ethanol exposure typically select one developmental window to simulate a specific context equivalent of human embryogenesis, and study consequences of ethanol exposure within that particular developmental epoch. Exposure timing is likely a large determinant in the neurobehavioral consequence of early ethanol exposure, as each brain region is variably susceptible to ethanol cytotoxicity and has unique sensitive periods in their development. We made a parallel comparison of the long-term effects of single-day binge ethanol at either embryonic day 8 (E8) or postnatal day 7 (P7) in male and female mice, and here demonstrate the differential long-term impacts on neuroanatomy, behavior and in vivo electrophysiology of two systems with very different developmental trajectories. The significant long-term differences in odor-evoked activity, local circuit inhibition, and spontaneous coherence between brain regions in the olfacto-hippocampal pathway that were found as a result of developmental ethanol exposure, varied based on insult timing. Long-term effects on cell proliferation and interneuron cell density were also found to vary by insult timing as well as by region. Finally, spatial memory performance and object exploration were affected in P7-exposed mice, but not E8-exposed mice. Our physiology and behavioral results are conceptually coherent with the neuroanatomical data attained from these same mice. Our results recognize both variable and shared effects of ethanol exposure timing on long-term circuit function and their supported behavior. PMID:25241068

  11. Avoidance test with Enchytraeus albidus (Enchytraeidae): effects of different exposure time and soil properties.

    PubMed

    Amorim, Mónica J B; Novais, Sara; Römbke, Jörg; Soares, Amadeu M V M

    2008-09-01

    Enchytraeids are ecologically relevant soil species and are commonly used in standardized toxicity tests. Their rapid reaction to a chemical exposure can be used as a toxicological measurement endpoint that assesses the avoidance behavior. The objectives of this investigation were to determine the effects of soil properties on the avoidance behavior of Enchytraeus albidus and to optimize the duration of avoidance test. The avoidance tests included (1) exposures in OECD artificial soil with standard or modified properties (pH, clay or peat content), and (2) exposures to copper chloride, cadmium chloride, and to the organic pesticides dimethoate and phenmedipham for different time periods. Results showed that alteration of OECD soil constituents significantly affected the avoidance behavior of enchytraeids, and that the 48-h exposure was the optimal duration of the test. Consideration of soil properties is important for selecting appropriate experimental design and interpreting the results of the enchytraeid avoidance test. PMID:18069103

  12. Chronic Ethanol Exposure Produces Time- and Brain Region-Dependent Changes in Gene Coexpression Networks

    PubMed Central

    Osterndorff-Kahanek, Elizabeth A.; Becker, Howard C.; Lopez, Marcelo F.; Farris, Sean P.; Tiwari, Gayatri R.; Nunez, Yury O.; Harris, R. Adron; Mayfield, R. Dayne

    2015-01-01

    Repeated ethanol exposure and withdrawal in mice increases voluntary drinking and represents an animal model of physical dependence. We examined time- and brain region-dependent changes in gene coexpression networks in amygdala (AMY), nucleus accumbens (NAC), prefrontal cortex (PFC), and liver after four weekly cycles of chronic intermittent ethanol (CIE) vapor exposure in C57BL/6J mice. Microarrays were used to compare gene expression profiles at 0-, 8-, and 120-hours following the last ethanol exposure. Each brain region exhibited a large number of differentially expressed genes (2,000-3,000) at the 0- and 8-hour time points, but fewer changes were detected at the 120-hour time point (400-600). Within each region, there was little gene overlap across time (~20%). All brain regions were significantly enriched with differentially expressed immune-related genes at the 8-hour time point. Weighted gene correlation network analysis identified modules that were highly enriched with differentially expressed genes at the 0- and 8-hour time points with virtually no enrichment at 120 hours. Modules enriched for both ethanol-responsive and cell-specific genes were identified in each brain region. These results indicate that chronic alcohol exposure causes global ‘rewiring‘ of coexpression systems involving glial and immune signaling as well as neuronal genes. PMID:25803291

  13. Chronic ethanol exposure produces time- and brain region-dependent changes in gene coexpression networks.

    PubMed

    Osterndorff-Kahanek, Elizabeth A; Becker, Howard C; Lopez, Marcelo F; Farris, Sean P; Tiwari, Gayatri R; Nunez, Yury O; Harris, R Adron; Mayfield, R Dayne

    2015-01-01

    Repeated ethanol exposure and withdrawal in mice increases voluntary drinking and represents an animal model of physical dependence. We examined time- and brain region-dependent changes in gene coexpression networks in amygdala (AMY), nucleus accumbens (NAC), prefrontal cortex (PFC), and liver after four weekly cycles of chronic intermittent ethanol (CIE) vapor exposure in C57BL/6J mice. Microarrays were used to compare gene expression profiles at 0-, 8-, and 120-hours following the last ethanol exposure. Each brain region exhibited a large number of differentially expressed genes (2,000-3,000) at the 0- and 8-hour time points, but fewer changes were detected at the 120-hour time point (400-600). Within each region, there was little gene overlap across time (~20%). All brain regions were significantly enriched with differentially expressed immune-related genes at the 8-hour time point. Weighted gene correlation network analysis identified modules that were highly enriched with differentially expressed genes at the 0- and 8-hour time points with virtually no enrichment at 120 hours. Modules enriched for both ethanol-responsive and cell-specific genes were identified in each brain region. These results indicate that chronic alcohol exposure causes global 'rewiring' of coexpression systems involving glial and immune signaling as well as neuronal genes.

  14. Analysis of real-time mixture cytotoxicity data following repeated exposure using BK/TD models.

    PubMed

    Teng, S; Tebby, C; Barcellini-Couget, S; De Sousa, G; Brochot, C; Rahmani, R; Pery, A R R

    2016-08-15

    Cosmetic products generally consist of multiple ingredients. Thus, cosmetic risk assessment has to deal with mixture toxicity on a long-term scale which means it has to be assessed in the context of repeated exposure. Given that animal testing has been banned for cosmetics risk assessment, in vitro assays allowing long-term repeated exposure and adapted for in vitro - in vivo extrapolation need to be developed. However, most in vitro tests only assess short-term effects and consider static endpoints which hinder extrapolation to realistic human exposure scenarios where concentration in target organs is varies over time. Thanks to impedance metrics, real-time cell viability monitoring for repeated exposure has become possible. We recently constructed biokinetic/toxicodynamic models (BK/TD) to analyze such data (Teng et al., 2015) for three hepatotoxic cosmetic ingredients: coumarin, isoeugenol and benzophenone-2. In the present study, we aim to apply these models to analyze the dynamics of mixture impedance data using the concepts of concentration addition and independent action. Metabolic interactions between the mixture components were investigated, characterized and implemented in the models, as they impacted the actual cellular exposure. Indeed, cellular metabolism following mixture exposure induced a quick disappearance of the compounds from the exposure system. We showed that isoeugenol substantially decreased the metabolism of benzophenone-2, reducing the disappearance of this compound and enhancing its in vitro toxicity. Apart from this metabolic interaction, no mixtures showed any interaction, and all binary mixtures were successfully modeled by at least one model based on exposure to the individual compounds. PMID:27317371

  15. Task- and time-dependent weighting factors in a retrospective exposure assessment of chemical laboratory workers.

    PubMed

    Henn, Scott A; Utterback, David F; Waters, Kathleen M; Markey, Andrea M; Tankersley, William G

    2007-02-01

    A chemical exposure assessment was conducted for a cohort mortality study of 6157 chemical laboratory workers employed between 1943 and 1998 at four Department of Energy sites in Oak Ridge, Tennessee, and Aiken, South Carolina. Previous studies of chemical laboratory workers have included members within professional societies where exposure assessment was either limited or not feasible, or chemical processing employees where laboratory and production workers were combined. Because sufficient industrial hygiene records were unavailable for all four sites, weighted duration of employment was used as a surrogate for the magnitude of exposure. Potential exposure indices were calculated for each worker using number of days employed and weighting factors for frequency of contact and year of employment. A total of 591 unique laboratory job titles indicative of a chemical laboratory worker were collapsed into 18 general job title categories. Through discussions with current and retired workers, along with examination of historical organizational charts and job descriptions, the percentage of time with activities involving the direct handling of chemicals in the laboratory was estimated for each job title category. Scaled weighting factors of 1, 0.6, 0.3, and 0.05 were assigned to the job title categories representing 100%, 60%, 30%, and 5% of daily activities handling chemicals, respectively. Based on limited industrial hygiene monitoring data, personal radiation monitoring records, and professional judgment, weighting factors that declined 4% annually were applied to each year to account for improvements in laboratory technique, advancements in instrumentation, improvement in engineering controls, and increased safety awareness through time. The study cohort was separated into three categories of chemical exposures based on department level information: (1) inorganic, (2) mixed inorganic and organic, and (3) unknown. Potential exposure indices ranged from 0.15 to 6824

  16. Analysis of real-time mixture cytotoxicity data following repeated exposure using BK/TD models.

    PubMed

    Teng, S; Tebby, C; Barcellini-Couget, S; De Sousa, G; Brochot, C; Rahmani, R; Pery, A R R

    2016-08-15

    Cosmetic products generally consist of multiple ingredients. Thus, cosmetic risk assessment has to deal with mixture toxicity on a long-term scale which means it has to be assessed in the context of repeated exposure. Given that animal testing has been banned for cosmetics risk assessment, in vitro assays allowing long-term repeated exposure and adapted for in vitro - in vivo extrapolation need to be developed. However, most in vitro tests only assess short-term effects and consider static endpoints which hinder extrapolation to realistic human exposure scenarios where concentration in target organs is varies over time. Thanks to impedance metrics, real-time cell viability monitoring for repeated exposure has become possible. We recently constructed biokinetic/toxicodynamic models (BK/TD) to analyze such data (Teng et al., 2015) for three hepatotoxic cosmetic ingredients: coumarin, isoeugenol and benzophenone-2. In the present study, we aim to apply these models to analyze the dynamics of mixture impedance data using the concepts of concentration addition and independent action. Metabolic interactions between the mixture components were investigated, characterized and implemented in the models, as they impacted the actual cellular exposure. Indeed, cellular metabolism following mixture exposure induced a quick disappearance of the compounds from the exposure system. We showed that isoeugenol substantially decreased the metabolism of benzophenone-2, reducing the disappearance of this compound and enhancing its in vitro toxicity. Apart from this metabolic interaction, no mixtures showed any interaction, and all binary mixtures were successfully modeled by at least one model based on exposure to the individual compounds.

  17. Time Evolution of the Wettability of Supported Graphene under Ambient Air Exposure

    PubMed Central

    2016-01-01

    The wettability of graphene is both fundamental and crucial for interfacing in most applications, but a detailed understanding of its time evolution remains elusive. Here we systematically investigate the wettability of metal-supported, chemical vapor deposited graphene films as a function of ambient air exposure time using water and various other test liquids with widely different surface tensions. The wettability of graphene is not constant, but varies with substrate interactions and air exposure time. The substrate interactions affect the initial graphene wettability, where, for instance, water contact angles of ∼85 and ∼61° were measured for Ni and Cu supported graphene, respectively, after just minutes of air exposure. Analysis of the surface free energy components indicates that the substrate interactions strongly influence the Lewis acid–base component of supported graphene, which is considerably weaker for Ni supported graphene than for Cu supported graphene, suggesting that the classical van der Waals interaction theory alone is insufficient to describe the wettability of graphene. For prolonged air exposure, the effect of physisorption of airborne contaminants becomes increasingly dominant, resulting in an increase of water contact angle that follows a universal linear-logarithmic relationship with exposure time, until saturating at a maximum value of 92–98°. The adsorbed contaminants render all supported graphene samples increasingly nonpolar, although their total surface free energy decreases only by 10–16% to about 37–41 mJ/m2. Our finding shows that failure to account for the air exposure time may lead to widely different wettability values and contradicting arguments about the wetting transparency of graphene. PMID:26900413

  18. Time-Based Measurement of Personal Mite Allergen Bioaerosol Exposure over 24 Hour Periods.

    PubMed

    Tovey, Euan R; Liu-Brennan, Damien; Garden, Frances L; Oliver, Brian G; Perzanowski, Matthew S; Marks, Guy B

    2016-01-01

    Allergic diseases such as asthma and rhinitis are common in many countries. Globally the most common allergen associated with symptoms is produced by house dust mites. Although the bed has often been cited as the main site of exposure to mite allergens, surprisingly this has not yet been directly established by measurement due to a lack of suitable methods. Here we report on the development of novel methods to determine the pattern of personal exposure to mite allergen bioaerosols over 24-hour periods and applied this in a small field study using 10 normal adults. Air was sampled using a miniature time-based air-sampler of in-house design located close to the breathing zone of the participants, co-located with a miniature time-lapse camera. Airborne particles, drawn into the sampler at 2L/min via a narrow slot, were impacted onto the peripheral surface of a disk mounted on the hour-hand of either a 12 or 24 hour clock motor. The impaction surface was either an electret cloth, or an adhesive film; both novel for these purposes. Following a review of the time-lapse images, disks were post-hoc cut into subsamples corresponding to eight predetermined categories of indoor or outdoor location, extracted and analysed for mite allergen Der p 1 by an amplified ELISA. Allergen was detected in 57.2% of the total of 353 subsamples collected during 20 days of sampling. Exposure patterns varied over time. Higher concentrations of airborne mite allergen were typically measured in samples collected from domestic locations in the day and evening. Indoor domestic Der p 1 exposures accounted for 59.5% of total exposure, whereas total in-bed-asleep exposure, which varied 80 fold between individuals, accounted overall for 9.85% of total exposure, suggesting beds are not often the main site of exposure. This study establishes the feasibility of novel methods for determining the time-geography of personal exposure to many bioaerosols and identifies new areas for future technical

  19. Time-Based Measurement of Personal Mite Allergen Bioaerosol Exposure over 24 Hour Periods

    PubMed Central

    Tovey, Euan R.; Liu-Brennan, Damien; Garden, Frances L.; Oliver, Brian G.; Perzanowski, Matthew S.; Marks, Guy B.

    2016-01-01

    Allergic diseases such as asthma and rhinitis are common in many countries. Globally the most common allergen associated with symptoms is produced by house dust mites. Although the bed has often been cited as the main site of exposure to mite allergens, surprisingly this has not yet been directly established by measurement due to a lack of suitable methods. Here we report on the development of novel methods to determine the pattern of personal exposure to mite allergen bioaerosols over 24-hour periods and applied this in a small field study using 10 normal adults. Air was sampled using a miniature time-based air-sampler of in-house design located close to the breathing zone of the participants, co-located with a miniature time-lapse camera. Airborne particles, drawn into the sampler at 2L/min via a narrow slot, were impacted onto the peripheral surface of a disk mounted on the hour-hand of either a 12 or 24 hour clock motor. The impaction surface was either an electret cloth, or an adhesive film; both novel for these purposes. Following a review of the time-lapse images, disks were post-hoc cut into subsamples corresponding to eight predetermined categories of indoor or outdoor location, extracted and analysed for mite allergen Der p 1 by an amplified ELISA. Allergen was detected in 57.2% of the total of 353 subsamples collected during 20 days of sampling. Exposure patterns varied over time. Higher concentrations of airborne mite allergen were typically measured in samples collected from domestic locations in the day and evening. Indoor domestic Der p 1 exposures accounted for 59.5% of total exposure, whereas total in-bed-asleep exposure, which varied 80 fold between individuals, accounted overall for 9.85% of total exposure, suggesting beds are not often the main site of exposure. This study establishes the feasibility of novel methods for determining the time-geography of personal exposure to many bioaerosols and identifies new areas for future technical

  20. Immunomodulatory Effects of Domoic Acid Differ Between In vivo and In vitro Exposure in Mice

    PubMed Central

    Levin, Milton; Leibrecht, Heather; Ryan, James; Van Dolah, Frances; De Guise, Sylvain

    2008-01-01

    The immunotoxic potential of domoic acid (DA), a well-characterized neurotoxin, has not been fully investigated. Phagocytosis and lymphocyte proliferation were evaluated following in vitro and in vivo exposure to assay direct vs indirect effects. Mice were injected intraperitoneally with a single dose of DA (2.5 μg/g b.w.) and sampled after 12, 24, or 48 hr. In a separate experiment, leukocytes and splenocytes were exposed in vitro to 0, 1, 10, or 100 μM DA. In vivo exposure resulted in a significant increase in monocyte phagocytosis (12-hr), a significant decrease in neutrophil phagocytosis (24-hr), a significant decrease in monocyte phagocytosis (48-hr), and a significant reduction in T-cell mitogen-induced lymphocyte proliferation (24-hr). In vitro exposure significantly reduced neutrophil and monocyte phagocytosis at 1 μM. B- and T-cell mitogen-induced lymphocyte proliferation were both significantly increased at 1 and 10 μM, and significantly decreased at 100 μM. Differences between in vitro and in vivo results suggest that DA may exert its immunotoxic effects both directly and indirectly. Modulation of cytosolic calcium suggests that DA exerts its effects through ionotropic glutamate subtype surface receptors at least on monocytes. This study is the first to identify DA as an immunotoxic chemical in a mammalian species. PMID:19172200

  1. Accumulation of free amino acids during exposure to drought in three springtail species.

    PubMed

    Holmstrup, Martin; Slotsbo, Stine; Rozsypal, Jan; Henriksen, Per G; Bayley, Mark

    2015-11-01

    Springtails are closely related to insects, but they differ from these with respect to water balance, in particular because springtails are small and have high integumental permeability to water. Here we report a series of experiments addressing the dynamics of osmoregulation, water content and accumulation of free amino acids (FAAs) in three springtail species during exposure to a gradually increasing environmental desiccation simulating conditions in drought exposed soil. Folsomia candida and Protaphorura fimata (both living in the deeper soil layers; euedaphic species) were active throughout the 3week exposure, with the developing drought regime ending at -3.56MPa (the soil water activity at the permanent wilting point of plants is -1.5MPa) and remained hyperosmotic (having an body fluid osmolality higher than the corresponding environment) to their surrounding air. Sinella curviseta (living in upper soil/litter layers; hemiedaphic species) also survived this exposure, but remained hypoosmotic throughout (i.e. with lower osmolality than the environment). The body content of most FAAs increased in response to drought in all three species. Alanine, proline and arginine were the most significantly upregulated FAAs. By combining our results with data in the literature, we could account for 82% of the observed osmolality at -3.56MPa in F. candida and 92% in P. fimata. The osmolality of S. curviseta was only slightly increased under drought, but here FAAs were considerably more important as osmolytes than in the two other species. We propose that FAAs probably have general importance in drought tolerance of springtails.

  2. Modeled Perfluorooctanoic Acid (PFOA) Exposure and Liver Function in a Mid-Ohio Valley Community

    PubMed Central

    Darrow, Lyndsey A.; Groth, Alyx C.; Winquist, Andrea; Shin, Hyeong-Moo; Bartell, Scott M.; Steenland, Kyle

    2016-01-01

    Background: Perfluorooctanoic acid (PFOA or C8) has hepatotoxic effects in animals. Cross-sectional epidemiologic studies suggest PFOA is associated with liver injury biomarkers. Objectives: We estimated associations between modeled historical PFOA exposures and liver injury biomarkers and medically validated liver disease. Methods: Participants completed surveys during 2008–2011 reporting demographic, medical, and residential history information. Self-reported liver disease, including hepatitis, fatty liver, enlarged liver and cirrhosis, was validated with healthcare providers. Alanine aminotransferase (ALT), γ-glutamyltransferase (GGT) and direct bilirubin, markers of liver toxicity, were obtained from blood samples collected in the C8 Health Project (2005–2006). Historically modeled PFOA exposure, estimated using environmental fate and transport models and participant residential histories, was analyzed in relation to liver biomarkers (n = 30,723, including 1,892 workers) and liver disease (n = 32,254, including 3,713 workers). Results: Modeled cumulative serum PFOA was positively associated with ALT levels (p for trend < 0.0001), indicating possible liver toxicity. An increase from the first to the fifth quintile of cumulative PFOA exposure was associated with a 6% increase in ALT levels (95% CI: 4, 8%) and a 16% increased odds of having above-normal ALT (95% CI: odds ratio: 1.02, 1.33%). There was no indication of association with either elevated direct bilirubin or GGT; however, PFOA was associated with decreased direct bilirubin. We observed no evidence of an effect of cumulative exposure (with or without a 10-year lag) on all liver disease (n = 647 cases), nor on enlarged liver, fatty liver, and cirrhosis only (n = 427 cases). Conclusion: Results are consistent with previous cross-sectional studies showing association between PFOA and ALT, a marker of hepatocellular damage. We did not observe evidence that PFOA increases the risk of clinically

  3. Maternal exposure to perfluoroalkyl acids measured in whole blood and birth outcomes in offspring.

    PubMed

    Callan, A C; Rotander, A; Thompson, K; Heyworth, J; Mueller, J F; Odland, J Ø; Hinwood, A L

    2016-11-01

    Perfluoralkyl and polyfluoralkyl substances have been measured in plasma and serum of pregnant women as a measure of prenatal exposure. Increased concentrations of individual perfluoroalkyl acids (PFAAs), (typically perfluorooctanoic acid (PFOA) and perfluoroctane sulfonate (PFOS) have been reported to be associated with reductions in birth weight and other birth outcomes. We undertook a study of 14 PFAAs in whole blood (including PFOS, PFHxS, PFHpA, PFOA, PFNA, PFDA and PFUnDA) from 98 pregnant women in Western Australia from 2008 to 2011. Median concentrations (in μg/L) were: PFOS 1.99; PFHxS 0.33; PFOA 0.86; PFNA 0.30; PFDA 0.12 and PFUnDA 0.08. Infants born to women with the highest tertile of PFHxS exposure had an increased odds of being <95% of their optimal birth weight (OR 3.5, 95% CI 1.1-11.5). Conversely, maternal blood concentrations of PFUnDA were associated with non-significant increases in average birth weight (+102g, 95% CI -41, 245) and significant increases in proportion of optimal birth weight (+4.7%, 95% CI 0.7, 8.8) per ln-unit change. This study has reported a range of PFAAs in the whole blood of pregnant women and suggests that PFHxS and PFUnDA may influence foetal growth and warrant further attention. Additional studies are required to identify the sources of PFAA exposure with a view to prevention, in addition to further studies investigating the long term health effects of these ubiquitous chemicals. PMID:27387804

  4. Excess perigestational folic acid exposure induces metabolic dysfunction in post-natal life.

    PubMed

    Keating, Elisa; Correia-Branco, Ana; Araújo, João R; Meireles, Manuela; Fernandes, Rita; Guardão, Luísa; Guimarães, João T; Martel, Fátima; Calhau, Conceição

    2015-03-01

    The aim of this study was to understand whether high folic acid (HFA) exposure during the perigestational period induces metabolic dysfunction in the offspring, later in life. To do this, female Sprague-Dawley rats (G0) were administered a dose of folic acid (FA) recommended for pregnancy (control, C, 2 mg FA/kg of diet, n=5) or a high dose of FA (HFA, 40 mg FA/kg of diet, n=5). Supplementation began at mating and lasted throughout pregnancy and lactation. Body weight and food and fluid intake were monitored in G0 and their offspring (G1) till G1 were 13 months of age. Metabolic blood profiles were assessed in G1 at 3 and 13 months of age (3M and 13M respectively). Both G0 and G1 HFA females had increased body weight gain when compared with controls, particularly 22 (G0) and 10 (G1) weeks after FA supplementation had been stopped. G1 female offspring of HFA mothers had increased glycemia at 3M, and both female and male G1 offspring of HFA mothers had decreased glucose tolerance at 13M, when compared with matched controls. At 13M, G1 female offspring of HFA mothers had increased insulin and decreased adiponectin levels, and G1 male offspring of HFA mothers had increased levels of leptin, when compared with matched controls. In addition, feeding of fructose to adult offspring revealed that perigestational exposure to HFA renders female progeny more susceptible to developing metabolic unbalance upon such a challenge. The results of this work indicate that perigestational HFA exposure the affects long-term metabolic phenotype of the offspring, predisposing them to an insulin-resistant state.

  5. Adaptive Responses to Prochloraz Exposure That Alter Dose-Response and Time-Course Behaviors

    EPA Science Inventory

    Dose response and time-course (DRTC) are, along with exposure, the major determinants of health risk. Adaptive changes within exposed organisms in response to environmental stress are common, and alter DRTC behaviors to minimize the effects caused by stressors. In this project, ...

  6. Early Adolescent Boys' Exposure to Internet Pornography: Relationships to Pubertal Timing, Sensation Seeking, and Academic Performance

    ERIC Educational Resources Information Center

    Beyens, Ine; Vandenbosch, Laura; Eggermont, Steven

    2015-01-01

    Research has demonstrated that adolescents regularly use Internet pornography. This two-wave panel study aimed to test an integrative model in early adolescent boys (M[subscript age] = 14.10; N = 325) that (a) explains their exposure to Internet pornography by looking at relationships with pubertal timing and sensation seeking, and (b) explores…

  7. Validation of trichloroacetic acid exposure via drinking water during pregnancy using a urinary TCAA biomarker.

    PubMed

    Smith, Rachel B; Nieuwenhuijsen, Mark J; Wright, John; Raynor, Pauline; Cocker, John; Jones, Kate; Kappaostopoulou-Karadanelli, Maria; Toledano, Mireille B

    2013-10-01

    Disinfection by-product (DBP) exposure during pregnancy may be related to reduced fetal growth, but the evidence is inconclusive and improved DBP exposure assessment is required. The authors conducted a nested exposure study on a subset (n=39) of pregnant women in the Born in Bradford cohort to assess validity of TCAA exposure assessment based on tap water sampling and self-reported water-use; water-use questionnaire validity; and use of a one-time urinary TCAA biomarker. TCAA levels in urine and home tap water supply were quantified, and water use was measured via a questionnaire and 7-day diary, at 28 weeks gestation. Diary and urine measures were repeated later in pregnancy (n=14). TCAA level in home tap water supply was not correlated with urinary TCAA (0.18, P=0.29). Cold unfiltered tap water intake at home measured by questionnaire was correlated with urinary TCAA (0.44, P=0.007), but correlation was stronger still for cold unfiltered tap water intake reported over the 3 days prior to urine sampling (0.60, P<0.001). For unemployed women TCAA ingestion at home, derived from tap water sampling and self-reported water-use, correlated strongly with urinary TCAA (0.78, P<0.001), but for employed women the correlation was weak (0.31, P=0.20). Results suggest individual tap water intake is most influential in determining TCAA exposure variability in this cohort, and that TCAA ingestion at home is a valid proxy for TCAA exposure for unemployed women but less satisfactory for employed women.

  8. Resistance to freshwater exposure in White Sea Littorina spp. II: Acid-base regulation.

    PubMed

    Sokolova, I M; Bock, C; Pörtner, H O

    2000-03-01

    Parameters of acid-base and energy status were studied by in vivo 31P-nuclear magnetic resonance spectroscopy in three White Sea Littorina spp. (L. littorea, L. saxatilis and L. obtusata) during prolonged anaerobiosis in freshwater. Intracellular pH decreased significantly, especially during the early period of anaerobiosis, but later the decrease in intracellular pH slowed down considerably, suggesting a capacity for intracellular pH regulation in all three species. There was a trend for intracellular pH to fall most rapidly in the least freshwater-resistant species, L. obtusata, as compared to the most resistant, L. littorea. Non-bicarbonate, non-phosphate buffer values estimated by the homogenate technique were similar in the three studied species (28-37 mmol pH(-1) kg(-1) wet weight) and did not change during freshwater exposure. The CaCO3 buffer value of the foot tissues was considerably higher (171-218 mmol pH(-1) kg(-1) wet weight) and decreased significantly during freshwater exposure. The contribution of the multiple tissue buffering systems to intracellular pH regulation in Littorina spp. shifts between different stages of freshwater exposure. Initially, the non-bicarbonate, non-phosphate tissue buffering system seems to be of major importance for metabolic proton buffering at intracellular pH between 7.5 and 7.0. During later stages of anaerobiosis and at lower intracellular pH, the CaCO3 buffer is involved in proton buffering. Decrease in the CaCO3 buffer value during freshwater exposure was in quantitative agreement with the amount of metabolic protons buffered, thus suggesting that CaCO3 tissue stores may serve as a major buffering system during prolonged anaerobiosis in Littorina spp. PMID:10791570

  9. Effects of sodium arsenate exposure on liver fatty acid profiles and oxidative stress in rats.

    PubMed

    Kharroubi, Wafa; Dhibi, Madiha; Haouas, Zohra; Chreif, Imed; Neffati, Fadoua; Hammami, Mohamed; Sakly, Rachid

    2014-02-01

    The present study aimed to evaluate the effect of arsenic on liver fatty acids (FA) composition, hepatotoxicity and oxidative status markers in rats. Male rats were randomly devised to six groups (n=10 per group) and exposed to sodium arsenate at a dose of 1 and 10 mg/l for 45 and 90 days. Arsenate exposure is associated with significant changes in the FA composition in liver. A significant increase of saturated fatty acids (SFA) in all treated groups (p<0.01) and trans unsaturated fatty acids (trans UFA) in rats exposed both for short term for 10 mg/l (p<0.05) and long term for 1 and 10 mg/l (p<0.001) was observed. However, the cis UFA were significantly decreased in these groups (p<0.05). A markedly increase of indicator in cell membrane viscosity expressed as SFA/UFA was reported in the treated groups (p<0.001). A significant increase in the level of malondialdehyde by 38.3 % after 90 days of exposure at 10 mg/l was observed. Compared to control rats, significant liver damage was observed at 10 mg/l of arsenate by increasing plasma marker enzymes after 90 days. It is through the histological investigations in hepatic tissues of exposed rats that these damage effects of arsenate were confirmed. The antioxidant perturbations were observed to be more important at groups treated by the high dose (p<0.05). An increase in the level of protein carbonyls was observed in all treated groups (p<0.05). The present study provides evidence for a direct effect of arsenite on FA composition disturbance causing an increase of SFA and TFAs isomers, liver dysfunction and oxidative stress. Therefore, arsenate can lead to hepatic damage and propensity towards liver cancer. PMID:23949113

  10. Upscaling heterogeneity in aquifer reactivity via exposure-time concept: forward model.

    PubMed

    Seeboonruang, Uma; Ginn, Timothy R

    2006-03-20

    Reactive properties of aquifer solid phase materials play an important role in solute fate and transport in the natural subsurface on time scales ranging from years in contaminant remediation to millennia in dynamics of aqueous geochemistry. Quantitative tools for dealing with the impact of natural heterogeneity in solid phase reactivity on solute fate and transport are limited. Here we describe the use of a structural variable to keep track of solute flux exposure to reactive surfaces. With this approach, we develop a non-reactive tracer model that is useful for determining the signature of multi-scale reactive solid heterogeneity in terms of solute flux distributions at the field scale, given realizations of three-dimensional reactive site density fields. First, a governing Eulerian equation for the non-reactive tracer model is determined by an upscaling technique in which it is found that the exposure time of solution to reactive surface areas evolves via both a macroscopic velocity and a macroscopic dispersion in the artificial dimension of exposure time. Second, we focus on the Lagrangian approach in the context of a streamtube ensemble and demonstrate the use of the distribution of solute flux over the exposure time dimension in modeling two-dimensional transport of a solute undergoing simplified linear reversible reactions, in hypothetical conditions following prior laboratory experiments. The distribution of solute flux over exposure time in a given case is a signature of the impact of heterogeneous aquifer reactivity coupled with a particular physical heterogeneity, boundary conditions, and hydraulic gradient. Rigorous application of this approach in a simulation sense is limited here to linear kinetically controlled reactions.

  11. Temporal variation of optimal UV exposure time over Korea: risks and benefits of surface UV radiation

    NASA Astrophysics Data System (ADS)

    Lee, Y. G.; Koo, J. H.

    2015-12-01

    Solar UV radiation in a wavelength range between 280 to 400 nm has both positive and negative influences on human body. Surface UV radiation is the main natural source of vitamin D, providing the promotion of bone and musculoskeletal health and reducing the risk of a number of cancers and other medical conditions. However, overexposure to surface UV radiation is significantly related with the majority of skin cancer, in addition other negative health effects such as sunburn, skin aging, and some forms of eye cataracts. Therefore, it is important to estimate the optimal UV exposure time, representing a balance between reducing negative health effects and maximizing sufficient vitamin D production. Previous studies calculated erythemal UV and vitamin-D UV from the measured and modelled spectral irradiances, respectively, by weighting CIE Erythema and Vitamin D3 generation functions (Kazantzidis et al., 2009; Fioletov et al., 2010). In particular, McKenzie et al. (2009) suggested the algorithm to estimate vitamin-D production UV from erythemal UV (or UV index) and determined the optimum conditions of UV exposure based on skin type Ⅱ according to the Fitzpatrick (1988). Recently, there are various demands for risks and benefits of surface UV radiation on public health over Korea, thus it is necessary to estimate optimal UV exposure time suitable to skin type of East Asians. This study examined the relationship between erythemally weighted UV (UVEry) and vitamin D weighted UV (UVVitD) over Korea during 2004-2012. The temporal variations of the ratio (UVVitD/UVEry) were also analyzed and the ratio as a function of UV index was applied in estimating the optimal UV exposure time. In summer with high surface UV radiation, short exposure time leaded to sufficient vitamin D and erythema and vice versa in winter. Thus, the balancing time in winter was enough to maximize UV benefits and minimize UV risks.

  12. Lead exposure in the lead-acid storage battery manufacturing and PVC compounding industries.

    PubMed

    Ho, S F; Sam, C T; Embi, G B

    1998-09-01

    This study was conducted as part of the Human Exposure Assessment Location (HEAL) Project which comes under the United Nations Environment Programme/World Health Organisation (UNEP/WHO) Global environmental Monitoring System (GEMS). The objective of the study was to evaluate workers' exposure to lead in industries with the highest exposure. All subjects were interviewed about their occupational and smoking histories, the use of personal protective equipment and personal hygiene. The contribution of a dietary source of lead intake from specified foods known to contain lead locally and personal air sampling for lead were assessed. A total of 61 workers from two PVC compounding and 50 workers from two lead acid battery manufacturing plants were studied together with 111 matched controls. In the PVC compounding plants the mean lead-in-air level was 0.0357 mg/m3, with the highest levels occurring during the pouring and mixing operations. This was lower than the mean lead-in-air level of 0.0886 mg/m3 in the lead battery manufacturing plants where the highest exposure was in the loading of lead ingots into milling machines. Workers in lead battery manufacturing had significantly higher mean blood lead than the PVC workers (means, 32.51 and 23.91 mcg/100 ml respectively), but there was poor correlation with lead-in-air levels. Among the lead workers, the Malays had significantly higher blood lead levels than the Chinese (mean blood levels were 33.03 and 25.35 mcg/100 ml respectively) although there was no significant difference between the two ethnic groups in the control group. There were no significant differences between the exposed and control group in terms of dietary intake of specified local foods known to contain lead. However, Malays consumed significantly more fish than the Chinese did. There were no ethnic differences in the hours of overtime work, number of years of exposure, usage of gloves and respirators and smoking habits. Among the Malays, 94.3% eat with

  13. Choosing optimal exposure times for XRF core-scanning: Suggestions based on the analysis of geological reference materials

    NASA Astrophysics Data System (ADS)

    Huang, Jyh-Jaan; Löwemark, Ludvig; Chang, Queenie; Lin, Tzu-Yu; Chen, Huei-Fen; Song, Sheng-Rong; Wei, Kuo-Yen

    2016-04-01

    X-ray fluorescence (XRF) core-scanning is a fast and nondestructive technique to assess elemental variations of unprocessed sediments. However, although the exposure time of XRF-scanning directly affects the scanning counts and total measurement time, only a few studies have considered the influence of exposure time during the scan. How to select an optimal exposure time to achieve reliable results and reduce the total measurement time is an important issue. To address this question, six geological reference materials from the Geological Survey of Japan (JLK-1, JMS-1, JMS-2, JSD-1, JSD-2, and JSD-3) were scanned by the Itrax-XRF core scanner using the Mo- and the Cr-tube with different exposure times to allow a comparison of scanning counts with absolute concentrations. The regression lines and correlation coefficients of elements that are generally used in paleoenvironmental studies were examined for the different exposure times and X-ray tubes. The results show that for those elements with relatively high concentrations or high detectability, the correlation coefficients are higher than 0.90 for all exposure times. In contrast, for the low detectability or low concentration elements, the correlation coefficients are relatively low, and improve little with increased exposure time. Therefore, we suggest that the influence of different exposure times is insignificant for the accuracy of the measurements. Thus, caution must be taken when interpreting the results of elements with low detectability, even when the exposure times are long and scanning counts are reasonably high.

  14. Atrazine exposure affects longevity, development time and body size in Drosophila melanogaster.

    PubMed

    Marcus, Sarah R; Fiumera, Anthony C

    2016-01-01

    Atrazine is the one of the most widely used herbicides in the United States and non-target organisms may encounter it in the environment. Atrazine is known to affect male reproduction in both vertebrates and invertebrates but less is known about its effects on other fitness traits. Here we assessed the effects of five different chronic exposure levels on a variety of fitness traits in Drosophila melanogaster. We measured male and female longevity, development time, proportion pupated, proportion emerged, body size, female mating rate, fertility and fecundity. Atrazine exposure decreased the proportion pupated, the proportion emerged and adult survival. Development time was also affected by atrazine and exposed flies pupated and emerged earlier than controls. Although development time was accelerated, body size was actually larger in some of the exposures. Atrazine exposure had no effect on female mating rate and the effects on female fertility and fecundity were only observed in one of the two independent experimental blocks. Many of the traits showed non-monotonic dose response curves, where the intermediate concentrations showed the largest effects. Overall this study shows that atrazine influences a variety of life history traits in the model genetic system, D. melanogaster, and future studies should aim to identify the molecular mechanisms of toxicity. PMID:27317622

  15. Fatty acid composition of spruce needle lipids after exposure to air pollutants

    SciTech Connect

    Wolfenden, J.; Wellburn, A.R. )

    1990-05-01

    Alterations in the fatty acid composition of membrane lipids have been observed in long-term experiments using realistic exposures of air pollutants. Monogalactosyl diglyceride (MGDG), from red spruce, showed a 12% reduction in linolenic acid (18:3) compared with controls, after a 21 week winter fumigation with SO{sub 2} NO{sub 2} (20 ppb each). The composition of phosphatidyl choline from the same trees was unaffected. In Norway spruce exposed to 70 ppb O{sub 3} for 3 consecutive summers there was no treatment effect on 18:3 content of MGDG, which ranged from 70 to 80%, with highest values in November. The percentage of octadecatetranoic acid (18:4) also varied seasonally. Compared with controls, polluted plants had proportionally less 18:4 during autumn, perhaps indicating some effect of O{sub 3} on the winter hardening process. Our observations emphasize the need for long-term experiments to investigate subtle disturbances to seasonal metabolic cycles.

  16. Personal exposure to ultrafine particles: the influence of time-activity patterns.

    PubMed

    Buonanno, G; Stabile, L; Morawska, L

    2014-01-15

    Exposure to ultrafine particles (UFPs) is deemed to be a major risk affecting human health. Therefore, airborne particle studies were performed in the recent years to evaluate the most critical micro-environments, as well as identifying the main UFP sources. Nonetheless, in order to properly evaluate the UFP exposure, personal monitoring is required as the only way to relate particle exposure levels to the activities performed and micro-environments visited. To this purpose, in the present work, the results of experimental analysis aimed at showing the effect of the time-activity patterns on UFP personal exposure are reported. In particular, 24 non-smoking couples (12 during winter and summer time, respectively), comprised of a man who worked full-time and a woman who was a homemaker, were analyzed using personal particle counter and GPS monitors. Each couple was investigated for a 48-h period, during which they also filled out a diary reporting the daily activities performed. Time activity patterns, particle number concentration exposure and the related dose received by the participants, in terms of particle alveolar-deposited surface area, were measured. The average exposure to particle number concentration was higher for women during both summer and winter (Summer: women 1.8 × 10(4) part. cm(-3); men 9.2 × 10(3) part. cm(-3); Winter: women 2.9 × 10(4) part. cm(-3); men 1.3 × 10(4) part. cm(-3)), which was likely due to the time spent undertaking cooking activities. Staying indoors after cooking also led to higher alveolar-deposited surface area dose for both women and men during the winter time (9.12 × 10(2) and 6.33 × 10(2) mm(2), respectively), when indoor ventilation was greatly reduced. The effect of cooking activities was also detected in terms of women's dose intensity (dose per unit time), being 8.6 and 6.6 in winter and summer, respectively. On the contrary, the highest dose intensity activity for men was time spent using transportation (2.8 in

  17. Developmental timing of sodium perchlorate exposure alters angiogenesis, thyroid follicle proliferation and sexual maturation in stickleback

    PubMed Central

    Furin, Christoff G.; von Hippel, Frank A.; Postlethwait, John H.; Buck, C. Loren; Cresko, William A.; O’Hara, Todd M.

    2015-01-01

    Perchlorate, a common aquatic contaminant, is well known to disrupt homeostasis of the hypothalamus-pituitary-thyroid axis. This study utilizes the threespine stickleback (Gasterosteus aculeatus) fish to determine if perchlorate exposure during certain windows of development has morphological effects on thyroid and gonads. Fish were moved from untreated water to perchlorate-contaminated water (30 and 100 mg/L) starting at 0, 3, 7, 14, 21, 42, 154 and 305 days post fertilization until approximately one year old. A reciprocal treatment (fish in contaminated water switched to untreated water) was conducted on the same schedule. Perchlorate exposure increased angiogenesis and follicle proliferation in thyroid tissue, delayed gonadal maturity, and skewed sex ratios towards males; effects depended on concentration and timing of exposure. This study demonstrates that perchlorate exposure beginning during the first 42 days of development has profound effects on stickleback reproductive and thyroid tissues, and by implication can impact population dynamics. Long-term exposure studies that assess contaminant effects at various stages of development provide novel information to characterize risk to aquatic organisms, to facilitate management of resources, and to determine sensitive developmental windows for further study of underlying mechanisms. PMID:25865142

  18. Developmental timing of sodium perchlorate exposure alters angiogenesis, thyroid follicle proliferation and sexual maturation in stickleback.

    PubMed

    Furin, Christoff G; von Hippel, Frank A; Postlethwait, John H; Buck, C Loren; Cresko, William A; O'Hara, Todd M

    2015-08-01

    Perchlorate, a common aquatic contaminant, is well known to disrupt homeostasis of the hypothalamus-pituitary-thyroid axis. This study utilizes the threespine stickleback (Gasterosteus aculeatus) fish to determine if perchlorate exposure during certain windows of development has morphological effects on thyroid and gonads. Fish were moved from untreated water to perchlorate-contaminated water (30 and 100mg/L) starting at 0, 3, 7, 14, 21, 42, 154 and 305 days post fertilization until approximately one year old. A reciprocal treatment (fish in contaminated water switched to untreated water) was conducted on the same schedule. Perchlorate exposure increased angiogenesis and follicle proliferation in thyroid tissue, delayed gonadal maturity, and skewed sex ratios toward males; effects depended on concentration and timing of exposure. This study demonstrates that perchlorate exposure beginning during the first 42 days of development has profound effects on stickleback reproductive and thyroid tissues, and by implication can impact population dynamics. Long-term exposure studies that assess contaminant effects at various stages of development provide novel information to characterize risk to aquatic organisms, to facilitate management of resources, and to determine sensitive developmental windows for further study of underlying mechanisms. PMID:25865142

  19. Time course of bronchial cell inflammation following exposure to diesel particulate matter using a modified EAVES.

    PubMed

    Hawley, Brie; McKenna, Dave; Marchese, Anthony; Volckens, John

    2014-08-01

    Electrostatic deposition of particles onto the surface of well-differentiated airway cells is a rapid and efficient means to screen for toxicity associated with exposure to fine and ultrafine particulate air pollution. This work describes the development and application of an electrostatic aerosol in vitro exposure system (EAVES) with increased throughput and ease-of-use. The modified EAVES accommodates standard tissue culture plates and uses an alternating electric field to deposit a net neutral charge of aerosol onto air-interface cell cultures. Using this higher-throughput design, we were able to examine the time-course (1, 3, 6, 9, and 24 h post-exposure) of transcript production and cytotoxicity in well-differentiated human bronchial cells exposed to diesel particulate matter at levels of 'real-world' significance. Statistically significant responses were observed at exposure levels (∼0.4 μg/cm(2)) much lower than typically reported in vitro using traditional submerged/resuspended techniques. Levels of HO-1, IL-8, CYP1A1, COX-2, and HSP-70 transcripts increased immediately following diesel particulate exposure and persisted for several hours; cytotoxicity was increased at 24h. The modified EAVES provides a platform for higher throughput, more efficient and representative testing of aerosol toxicity in vitro.

  20. Effects of radiant heat exposure on pacing pattern during a 15-km cycling time trial.

    PubMed

    Levels, Koen; de Koning, Jos; Broekhuijzen, Iris; Zwaan, Tamara; Foster, Carl; Daanen, Hein

    2014-01-01

    The goal of this study was to investigate the effects of different durations of skin temperature manipulation on pacing patterns and performance during a 15-km cycling time trial. Nineteen well-trained men completed three 15-km cycling time trials in 18 °C and 50% relative humidity with 4.5-km (short-heat), 9.0-km (long-heat) or without (control) radiant heat exposure applied by infrared heaters after 1.5 km in the time trial. During the time trials, power output, mean skin temperature, rectal temperature, heart rate and rating of perceived exertion were assessed. The radiant heat exposure resulted in higher mean skin temperature during the time trial for short-heat (35.0 ± 0.6 °C) and long-heat (35.3 ± 0.5 °C) than for control (32.5 ± 1.0 °C; P < 0.001), whereas rectal temperature was similar (P = 0.55). The mean power output was less for short-heat (273 ± 8 W; P = 0.001) and long-heat (271 ± 9 W; P = 0.02) than for control (287 ± 7 W), but pacing patterns did not differ (P = 0.55). Heart rate was greatest in control (177 ± 9 beats · min(-1); P < 0.001), whereas the rating of perceived exertion remained similar. We concluded that a radiant heat exposure and associated higher skin temperature reduced overall performance, but did not modify pacing pattern during a 15-km cycling time trial, regardless of the duration of the exposure.

  1. Phase-shifting human circadian rhythms: influence of sleep timing, social contact and light exposure

    NASA Technical Reports Server (NTRS)

    Duffy, J. F.; Kronauer, R. E.; Czeisler, C. A.

    1996-01-01

    1. Both the timing of behavioural events (activity, sleep and social interactions) and the environmental light-dark cycle have been reported to contribute to entrainment of human circadian rhythms to the 24 h day. Yet, the relative contribution of those putative behavioural synchronizers to that of light exposure remains unclear. 2. To investigate this, we inverted the schedule of rest, sedentary activity and social contact of thirty-two young men either with or without exposure to bright light. 3. On this inverted schedule, the endogenous component of the core temperature rhythm of subjects who were exposed to bright light showed a significant phase shift, demonstrating that they were adapting to the new schedule. In contrast, the core temperature rhythm of subjects who were not exposed to bright light moved on average 0.2 h later per day and after 10 days had not significantly adapted to the new schedule. 4. The direction of phase shift in the groups exposed to bright light was dependent on the time of bright light exposure, while control subjects drifted to a later hour regardless of the timing of their schedule of sleep timing, social contact and meals. 5. These results support the concept that the light-dark cycle is the most important synchronizer of the human circadian system. They suggest that inversion of the sleep-wake, rest-activity and social contact cycles provides relatively minimal drive for resetting the human circadian pacemaker. 6. These data indicate that interventions designed to phase shift human circadian rhythms for adjustment to time zone changes or altered work schedules should focus on properly timed light exposure.

  2. Potential effects of tooth-brushing on human dentin wear following exposure to acidic soft drinks.

    PubMed

    Choi, S; Park, K-H; Cheong, Y; Moon, S W; Park, Y-G; Park, H-K

    2012-08-01

    This study used scanning electron microscopy and atomic force microscopy to examine the short-term potential effects of brushing time and the start-time of tooth-brushing after demineralization on primary dentin wear in vitro. Thirty-six noncarious primary central incisors were assigned to 12 experimental groups. Exposure to cola drinks was used to initiate the demineralization process. Three brushing times (5, 15 and 30 s) and four start-times of brushing (0, 30, 60 and 120 min) after an erosive attack were used for the abrasion process. Tooth-brushing the softened dentin surface led to increases in the open tubular fraction and microstructural changes on the dentin surface. Brushing immediately after exposure to cola resulted in the greatest irreversible dentin loss, whereas brushing 60 or 120 min after pretreatment resulted in the least irreversible dentin loss. However, brushing time had no effect on the irreversible loss of dentin wear. Based on these experimental results, tooth-brushing should be performed at least 60 min after consuming a cola drink to achieve the desired tooth cleaning and avoid the introduction of surface lesions on dentin.

  3. Reexamination of London, England, mortality in relation to exposure to acidic aerosols during 1963-1972 winters

    SciTech Connect

    Thurston, G.D.; Ito, K.; Lippmann, M.; Hayes, C.

    1989-02-01

    Air pollution epidemiology since the 1950s has been able to demonstrate that increases in daily mortality in London, England, were associated with elevated concentrations of index air pollutants, i.e., British Smoke (BS) and sulfur dioxide (SO/sub 2/). In this work, we reanalyze that portion of the 1958-1972 winter mortality-pollution record for which daily direct acid aerosol measurements were made at a central site in London (St. Bartholomew's Medical College). The purposes of these exploratory analyses are to examine the dataset for indications of a relationship between acid aerosol pollution and human mortality and to compare any noted associations with those for other pollution variables. It is found that the log of acid aerosol concentrations is more strongly associated with raw total mortality in bivariate analyses than is BS or SO2, despite the fact that acid data are available from only one central site (versus seven disperse sites for BS and SO/sub 2/). The logarithmic nature of the exposure side of the H/sub 2/SO/sub 4/-mortality relationship implies a saturation model of pollution effects, possibly due to multiday pollution harvesting influences on a susceptible subpopulation. Moreover, mortality-pollution cross-correlation analyses indicate that mortality effects usually follow pollution in time, supporting a causal relationship between the two. The apparent advantage of H/sub 2/SO/sub 4/ over BS in predicting total raw mortality is consistent with the hypothesis that it is the portion of particulate mass of greater health significance and may also allow the development of London mortality results which are more easily transferable to other environments than is the case for existing BS results.

  4. Reexamination of London, England, mortality in relation to exposure to acidic aerosols during 1963-1972 winters.

    PubMed

    Thurston, G D; Ito, K; Lippmann, M; Hayes, C

    1989-02-01

    Air pollution epidemiology since the 1950s has been able to demonstrate that increases in daily mortality in London, England, were associated with elevated concentrations of index air pollutants, i.e., British Smoke (BS) and sulfur dioxide (SO2). In this work, we reanalyze that portion of the 1958-1972 winter mortality-pollution record for which daily direct acid aerosol measurements were made at a central site in London (St. Bartholomew's Medical College). The purposes of these exploratory analyses are to examine the dataset for indications of a relationship between acid aerosol pollution and human mortality and to compare any noted associations with those for other pollution variables. It is found that the log of acid aerosol concentrations is more strongly associated with raw total mortality in bivariate analyses than is BS or SO2, despite the fact that acid data are available from only one central site (versus seven disperse sites for BS and SO2). The logarithmic nature of the exposure side of the H2SO4-mortality relationship implies a saturation model of pollution effects, possibly due to multiday pollution harvesting influences on a susceptible subpopulation. Moreover, mortality-pollution cross-correlation analyses indicate that mortality effects usually follow pollution in time, supporting a causal relationship between the two. The apparent advantage of H2SO4 over BS in predicting total raw mortality is consistent with the hypothesis that it is the portion of particulate mass of greater health significance and may also allow the development of London mortality results which are more easily transferable to other environments than is the case for existing BS results.

  5. Reexamination of London, England, mortality in relation to exposure to acidic aerosols during 1963-1972 winters.

    PubMed Central

    Thurston, G D; Ito, K; Lippmann, M; Hayes, C

    1989-01-01

    Air pollution epidemiology since the 1950s has been able to demonstrate that increases in daily mortality in London, England, were associated with elevated concentrations of index air pollutants, i.e., British Smoke (BS) and sulfur dioxide (SO2). In this work, we reanalyze that portion of the 1958-1972 winter mortality-pollution record for which daily direct acid aerosol measurements were made at a central site in London (St. Bartholomew's Medical College). The purposes of these exploratory analyses are to examine the dataset for indications of a relationship between acid aerosol pollution and human mortality and to compare any noted associations with those for other pollution variables. It is found that the log of acid aerosol concentrations is more strongly associated with raw total mortality in bivariate analyses than is BS or SO2, despite the fact that acid data are available from only one central site (versus seven disperse sites for BS and SO2). The logarithmic nature of the exposure side of the H2SO4-mortality relationship implies a saturation model of pollution effects, possibly due to multiday pollution harvesting influences on a susceptible subpopulation. Moreover, mortality-pollution cross-correlation analyses indicate that mortality effects usually follow pollution in time, supporting a causal relationship between the two. The apparent advantage of H2SO4 over BS in predicting total raw mortality is consistent with the hypothesis that it is the portion of particulate mass of greater health significance and may also allow the development of London mortality results which are more easily transferable to other environments than is the case for existing BS results. PMID:2785034

  6. Quantification of naphthoquinone mercapturic acids in urine as biomarkers of naphthalene exposure.

    PubMed

    Klotz, Katrin; Angerer, Jürgen

    2016-02-15

    Naphthalene shows carcinogenic properties in animal experiments. As the substance is ubiquitary present in the environment and has a possibly high exposure at industrial workplaces, the determination of naphthalene metabolites in humans is of environmental-medical as well as occupational-medical importance. Here, biomarkers of 1,2- and 1,4-naphthoquinone, as possibly carcinogenic metabolites in the naphthalene metabolism, are of outstanding significance. We developed and validated a liquid chromatography-tandem mass-spectrometric (LC-MS/MS) method for the simultaneous determination of the naphthoquinone mercapturic acids of 1,2- and 1,4-naphthoquinone in human urine samples as a sum of naphthoquinone- and dihydroxynaphthalene-mercapturic acid. Except for enzymatic hydrolysis and acidification, no further sample preparation is necessary. For sample clean-up, a column switching procedure is applied. The mercapturic acids are extracted from the urinary matrix on a restricted access material (RAM RP 18) and separated on a reversed phase column (Synergi Polar RP C18). The metabolites were quantified by tandem mass spectrometry using labelled D5-1,4-NQMA as internal standard. The limits of detection are 3μg/l for 1,2-NQMA and 1μg/l for 1,4-NQMA. Intraday- and interday precision for pooled urine (spiked with 10μg/l and 30μg/l of the analytes) ranges from 5.9 to 15.1% for 1,2-NQMA and from 2.0 to 10.8% for 1,4-NQMA. The developed method is suited for the sensitive and specific determination of the mercapturic acids of naphthoquinones in human urine. A good precision and low limits of detection were achieved. Application of those new biomarkers in biomonitoring studies may give deeper insights into the mechanisms of the human naphthalene metabolism. PMID:26812176

  7. An examination of exposure measurement error from air pollutant spatial variability in time-series studies.

    PubMed

    Sarnat, Stefanie E; Klein, Mitchel; Sarnat, Jeremy A; Flanders, W Dana; Waller, Lance A; Mulholland, James A; Russell, Armistead G; Tolbert, Paige E

    2010-03-01

    Relatively few studies have evaluated the effects of heterogeneous spatiotemporal pollutant distributions on health risk estimates in time-series analyses that use data from a central monitor to assign exposures. We present a method for examining the effects of exposure measurement error relating to spatiotemporal variability in ambient air pollutant concentrations on air pollution health risk estimates in a daily time-series analysis of emergency department visits in Atlanta, Georgia. We used Poisson generalized linear models to estimate associations between current-day pollutant concentrations and circulatory emergency department visits for the 1998-2004 time period. Data from monitoring sites located in different geographical regions of the study area and at different distances from several urban geographical subpopulations served as alternative measures of exposure. We observed associations for spatially heterogeneous pollutants (CO and NO(2)) using data from several different urban monitoring sites. These associations were not observed when using data from the most rural site, located 38 miles from the city center. In contrast, associations for spatially homogeneous pollutants (O(3) and PM(2.5)) were similar, regardless of the monitoring site location. We found that monitoring site location and the distance of a monitoring site to a population of interest did not meaningfully affect estimated associations for any pollutant when using data from urban sites located within 20 miles from the population center under study. However, for CO and NO(2), these factors were important when using data from rural sites located > or = 30 miles from the population center, most likely owing to exposure measurement error. Overall, our findings lend support to the use of pollutant data from urban central sites to assess population exposures within geographically dispersed study populations in Atlanta and similar cities. PMID:19277071

  8. Exposure measurement error in time-series studies of air pollution: concepts and consequences.

    PubMed Central

    Zeger, S L; Thomas, D; Dominici, F; Samet, J M; Schwartz, J; Dockery, D; Cohen, A

    2000-01-01

    Misclassification of exposure is a well-recognized inherent limitation of epidemiologic studies of disease and the environment. For many agents of interest, exposures take place over time and in multiple locations; accurately estimating the relevant exposures for an individual participant in epidemiologic studies is often daunting, particularly within the limits set by feasibility, participant burden, and cost. Researchers have taken steps to deal with the consequences of measurement error by limiting the degree of error through a study's design, estimating the degree of error using a nested validation study, and by adjusting for measurement error in statistical analyses. In this paper, we address measurement error in observational studies of air pollution and health. Because measurement error may have substantial implications for interpreting epidemiologic studies on air pollution, particularly the time-series analyses, we developed a systematic conceptual formulation of the problem of measurement error in epidemiologic studies of air pollution and then considered the consequences within this formulation. When possible, we used available relevant data to make simple estimates of measurement error effects. This paper provides an overview of measurement errors in linear regression, distinguishing two extremes of a continuum-Berkson from classical type errors, and the univariate from the multivariate predictor case. We then propose one conceptual framework for the evaluation of measurement errors in the log-linear regression used for time-series studies of particulate air pollution and mortality and identify three main components of error. We present new simple analyses of data on exposures of particulate matter < 10 microm in aerodynamic diameter from the Particle Total Exposure Assessment Methodology Study. Finally, we summarize open questions regarding measurement error and suggest the kind of additional data necessary to address them. Images Figure 1 Figure 2

  9. Kinetics of Antibody Aggregation at Neutral pH and Ambient Temperatures Triggered by Temporal Exposure to Acid.

    PubMed

    Imamura, Hiroshi; Honda, Shinya

    2016-09-15

    The purification process of an antibody in manufacturing involves temporal exposure of the molecules to low pH followed by neutralization-pH-shift stress-which causes aggregation. It remains unclear how aggregation triggered by pH-shift stress grows at neutral pH and how it depends on the temperature in an ambient range. We used static and dynamic light scattering to monitor the time-dependent evolution of the aggregate size of the pH-shift stressed antibody between 4.0 and 40.0 °C. A power-law relationship between the effective molecular weight and the effective hydrodynamic radius was found, indicating that the aggregates were fractal with a dimension of 1.98. We found that the aggregation kinetics in the lower-temperature range, 4.0-25.0 °C, were well described by the Smoluchowski aggregation equation. The temperature dependence of the effective aggregation rate constant gave 13 ± 1 kcal/mol of endothermic activation energy. Temporal acid exposure creates an enriched population of unfolded protein molecules that are competent of aggregating. Therefore, the energetically unfavorable unfolding step is not required and the aggregation proceeds faster. These findings provide a basis for predicting the growth of aggregates during storage under practical, ambient conditions. PMID:27537343

  10. Effects of in utero retinoic acid exposure on mouse pelage hair follicle development.

    PubMed

    García-Fernández, Rosa A; Pérez-Martínez, Claudia; Escudero-Diez, Alfredo; García-Iglesias, Maria J

    2002-06-01

    We investigated in vivo the histological and immunohistochemical responses of mouse hair pelage follicle morphogenesis to prenatal exposure to a potentially nonteratogenic dose of all-trans-retinoic acid (RA), as a basis studying the preventive effect of RA on adult mouse skin carcinogenesis. In pregnant mice, a single oral dose of RA at 30 mg kg-1 body weight given on day 11.5 of gestation caused no RA-induced changes in the morphology or temporal expression patterns of keratins during pelage hair follicle morphogenesis. The only differential effect of RA was a statistically significant increase in the number of BrdU-positive nuclei in hair bulbs from RA exposed fetuses compared with nonexposed mice. The absence of adverse RA effects suggests that this experimental design may represent a valuable protocol for use in studies on the in vivo effects of this retinoid on different skin diseases.

  11. The ameliorative effect of ascorbic acid and Ginkgo biloba on learning and memory deficits associated with fluoride exposure

    PubMed Central

    Raghuveer, Vasudeva C.; Rao, Mallikarjuna C.; Somayaji, Nagabhooshana S.; Babu, Prakash B.

    2013-01-01

    Chronic exposure to fluoride causes dental and skeletal fluorosis. Fluoride exposure is also detrimental to soft tissues and organs. The present study aimed at evaluation of the effect of Ginkgo biloba and ascorbic acid on learning and memory deficits caused by fluoride exposure. Male Wistar rats were divided into five groups (n=6). Group 1 control. Groups 2 to 5 received 100 ppm of sodium fluoride over 30 days. Groups 3, 4 and 5 were further treated for 15 days receiving respectively 1% gum acacia solution, 100 mg/kg body weight ascorbic acid, and 100mg/kg body weight Ginkgo biloba extract. After 45 days, all animals were subjected to behavioural tests. The results showed that fluoride affected learning and memory. Fluoride causes oxidative stress and neurodegeneration, thereby affecting learning and memory. Ascorbic acid and Ginkgo biloba were found to augment the reversal of learning and memory deficits caused by fluoride ingestion. PMID:24678261

  12. Measurement of fluid properties using rapid-double-exposure and time-average holographic interferometry

    NASA Astrophysics Data System (ADS)

    Decker, A. J.

    1984-06-01

    The holographic recording of the time history of a flow feature in three dimensions is discussed. The use of diffuse illumination holographic interferometry or the three dimensional visualization of flow features such as shock waves and turbulent eddies is described. The double-exposure and time-average methods are compared using the characteristic function and the results from a flow simulator. A time history requires a large hologram recording rate. Results of holographic cinematography of the shock waves in a flutter cascade are presented as an example. Future directions of this effort, including the availability and development of suitable lasers, are discussed.

  13. Measurement of fluid properties using rapid-double-exposure and time-average holographic interferometry

    NASA Technical Reports Server (NTRS)

    Decker, A. J.

    1984-01-01

    The holographic recording of the time history of a flow feature in three dimensions is discussed. The use of diffuse illumination holographic interferometry or the three dimensional visualization of flow features such as shock waves and turbulent eddies is described. The double-exposure and time-average methods are compared using the characteristic function and the results from a flow simulator. A time history requires a large hologram recording rate. Results of holographic cinematography of the shock waves in a flutter cascade are presented as an example. Future directions of this effort, including the availability and development of suitable lasers, are discussed.

  14. Measurement of fluid properties using rapid-double-exposure and time-average holographic interferometry

    NASA Technical Reports Server (NTRS)

    Decker, A. J.

    1984-01-01

    The holographic recording of the time history of a flow feature in three dimensions is discussed. The use of diffuse illumination holographic interferometry or the three-dimensional visualization of flow features such as shock waves and turbulent eddies is described. The double-exposure and time-average methods are compared using the characteristic function and the results from a flow simulator. A time history requires a large hologram recording rate. Results of holographic cinematography of the shock waves in a flutter cascade are presented as an example. Future directions of this effort, including the availability and development of suitable lasers, are discussed. Previously announced in STAR as N84-21849

  15. Exposure to omega-3 fatty acids at early age accelerate bone growth and improve bone quality.

    PubMed

    Koren, Netta; Simsa-Maziel, Stav; Shahar, Ron; Schwartz, Betty; Monsonego-Ornan, Efrat

    2014-06-01

    Omega-3 fatty acids (FAs) are essential nutritional components that must be obtained from foods. Increasing evidence validate that omega-3 FAs are beneficial for bone health, and several mechanisms have been suggested to mediate their effects on bone, including alterations in calcium absorption and urinary calcium loss, prostaglandin synthesis, lipid oxidation, osteoblast formation and inhibition of osteoclastogenesis. However, to date, there is scant information regarding the effect of omega-3 FAs on the developing skeleton during the rapid growth phase. In this study we aim to evaluate the effect of exposure to high levels of omega-3 FAs on bone development and quality during prenatal and early postnatal period. For this purpose, we used the fat-1 transgenic mice that have the ability to convert omega-6 to omega-3 fatty acids and the ATDC5 chondrogenic cell line as models. We show that exposure to high concentrations of omega-3 FAs at a young age accelerates bone growth through alterations of the growth plate, associated with increased chondrocyte proliferation and differentiation. We further propose that those effects are mediated by the receptors G-protein coupled receptor 120 (GPR120) and hepatic nuclear factor 4α, which are expressed by chondrocytes in culture. Additionally, using a combined study on the structural and mechanical bone parameters, we show that high omega-3 levels contribute to superior trabecular and cortical structure, as well as to stiffer bones and improved bone quality. Most interestingly, the fat-1 model allowed us to demonstrate the role of maternal high omega-3 concentration on bone growth during the gestation and postnatal period.

  16. Heat exposure increases circulating fatty acids but not lipid oxidation at rest and during exercise.

    PubMed

    O'Hearn, Katharine; Tingelstad, Hans Christian; Blondin, Denis; Tang, Vera; Filion, Lionel G; Haman, François

    2016-01-01

    Alterations in lipid oxidation during exercise have been well studied, but limited data exists on the effects of passive heat exposure and exercise in the heat on changes in lipid oxidation. This study was designed to examine: (1) the effects of heat exposure on lipid metabolism during passive heating and subsequent exercise in the heat by focusing on changes in whole-body lipid oxidation and plasma lipid concentrations, and (2) the effects of extended passive pre-heating on exercise performance in the heat. Male participants (n=8) were passively heated for 120 min at 42 °C, then exercised on a treadmill in the same temperature at 50% V̇O2 max for 30 min (HEAT). This same procedure was followed on a separate occasion at 23 °C (CON). Results showed that lipid oxidation rates were not different between HEAT and CON during passive heating or exercise. However, non-esterified fatty acid (NEFA) concentrations were significantly higher following passive heating (618 µM, 95% CI: 479-757) compared to CON (391 µM, 95% CI: 270-511). The same trend was observed following exercise (2036 µM, 95% CI: 1604-2469 for HEAT and 1351 µM, 95% CI: 1002-1699). Triacylglycerol, phospholipid and cholesterol levels were not different between HEAT and CON at any point. Four of 8 participants could not complete 30 min of exercise in HEAT, resulting in a 14% decline in total external work. Rate of perceived exertion over the final 5 min of exercise was higher in HEAT (9.5) than CON (5). We conclude that: (1) heat exposure results in increased circulating NEFA at rest and during exercise without changes in whole-body lipid utilization, and (2) passive pre-heating reduces work capacity during exercise in the heat and increases the perceived intensity of a given workload.

  17. Vulnerability to dietary n-3 polyunsaturated fatty acid deficiency after exposure to early stress in rats.

    PubMed

    Ferreira, Charles Francisco; Bernardi, Juliana Rombaldi; Krolow, Rachel; Arcego, Danusa Mar; Fries, Gabriel Rodrigo; de Aguiar, Bianca Wollenhaupt; Senter, Gabrielle; Kapczinski, Flávio Pereira; Silveira, Patrícia Pelufo; Dalmaz, Carla

    2013-06-01

    The exposure to adverse events early in life may affect brain development. Omega-3 polyunsaturated fatty acid (n-3 PUFA) deficiency has been linked to the development of mood and anxiety disorders. The aim of this study was to examine the interaction between variations in the early environment (handling or maternal separation) and the chronic exposure to a nutritional n-3 PUFA deficiency on locomotor activity, sucrose preference, forced swimming test and on serum and hippocampal brain-derived neurotrophic factor (BDNF) levels. Rats were randomized into Non-handled (NH), Neonatal Handled (H) and Maternal Separated (MS) groups. Pups were removed from their dams (incubator at 32°C on postnatal days (PND) 1-10) during 10 min/day (H) or 3h/day (MS). On PND 35, males were subdivided into diets adequate or deficient in n-3 PUFA for 15 weeks. H and MS gained weight differently, and animals receiving the n-3 PUFA deficient diet gained less weight. MS displayed a higher food consumption and higher consumption of sucrose solution during the second hour of exposure to the sucrose preference test. No differences were observed in the swimming test. H group had increased locomotion and showed a higher response to amfepramone. No significant effect was observed on serum BDNF levels. BDNF protein levels were decreased in animals receiving the n-3 PUFA deficient diet. We observed that early life environment and a mild n-3 PUFA deficiency are able to affect several behavioral aspects (food and sucrose consumption and locomotor response), and lead to a differential hippocampal BDNF metabolism in adult life.

  18. Lynch syndrome and exposure to aristolochic acid in upper-tract urothelial carcinoma: its clinical impact?

    PubMed Central

    Colin, Pierre; Seisen, Thomas; Mathieu, Romain; Shariat, Sharohkh F.

    2016-01-01

    The purpose of the current review was to describe the clinical risk for Lynch syndrome (LS) after exposure to aristolochic acid (AA) in cases of upper urinary-tract urothelial carcinoma (UTUC). A systematic review of the scientific literature was performed using the Medline database (National Library of Medicine, PubMed) using the following keywords: epidemiology, risk factor, AA, Balkan nephropathy (BNe), LS, hereditary cancer, hereditary non-polyposis colorectal cancer (HNPCC), mismatch repair genes, urothelial carcinomas, upper urinary tract, renal pelvis, ureter, Amsterdam criteria, genetic counselling, mismatch repair genes, genetic instability, microsatellite, and Bethesda guidelines. LS is a specific risk for UTUC, which is the third most frequent cancer (in its tumor spectrum) after colon and uterine lesions. Mutation of the MSH2 gene is the most commonly described cause of UTUC in LS. Diagnosis is based on clinical suspicion and is guided by Bethesda and Amsterdam criteria. It is secondarily confirmed by immunohistochemical analyses of the tumor and a search for gene mutations. The presence of LS in patients with UTUC is a favorable prognosis factor for survival during follow-ups. AA is a specific environmental risk factor for UTUC and tubulo-interstitial nephropathy. It has been involved in the development of nephropathies in link with the Balkan disease and intake of Chinese herbal medicine. More broadly, the use of traditional plant medicines from the genus Aristolochia has created worldwide public-health concerns. UTUCs share common risk factors with other urothelial carcinomas such as tobacco or occupational exposure. However, these tumors have also specific risk factors such as AA exposure and LS that clinicians should be aware of because of their clinical implication in further management and follow-up. PMID:27785421

  19. Accumulation of free amino acids during exposure to drought in three springtail species.

    PubMed

    Holmstrup, Martin; Slotsbo, Stine; Rozsypal, Jan; Henriksen, Per G; Bayley, Mark

    2015-11-01

    Springtails are closely related to insects, but they differ from these with respect to water balance, in particular because springtails are small and have high integumental permeability to water. Here we report a series of experiments addressing the dynamics of osmoregulation, water content and accumulation of free amino acids (FAAs) in three springtail species during exposure to a gradually increasing environmental desiccation simulating conditions in drought exposed soil. Folsomia candida and Protaphorura fimata (both living in the deeper soil layers; euedaphic species) were active throughout the 3week exposure, with the developing drought regime ending at -3.56MPa (the soil water activity at the permanent wilting point of plants is -1.5MPa) and remained hyperosmotic (having an body fluid osmolality higher than the corresponding environment) to their surrounding air. Sinella curviseta (living in upper soil/litter layers; hemiedaphic species) also survived this exposure, but remained hypoosmotic throughout (i.e. with lower osmolality than the environment). The body content of most FAAs increased in response to drought in all three species. Alanine, proline and arginine were the most significantly upregulated FAAs. By combining our results with data in the literature, we could account for 82% of the observed osmolality at -3.56MPa in F. candida and 92% in P. fimata. The osmolality of S. curviseta was only slightly increased under drought, but here FAAs were considerably more important as osmolytes than in the two other species. We propose that FAAs probably have general importance in drought tolerance of springtails. PMID:26428866

  20. Hematological effect of benzene exposure with emphasis of muconic acid as a biomarker.

    PubMed

    Ibrahim, Khadiga S; Amer, Nagat M; El-dossuky, Elsaid A; Emara, Ahmed M; El-Fattah, Abd El-Samei M Abd; Shahy, Eman Mohamed

    2014-06-01

    Human exposure to benzene in work environment is a global occupational health problem. It is established that benzene requires to be metabolized to induce its effects. Benzene has been associated with various hematotoxins and carcinogens. The aim of this study was to investigate the effect of benzene on complete blood picture, with emphasis of trans, trans-muconic acid (t,t-MA) as a biomarker of benzene in urine, considering the influence of cigarette smoke. A total of 81 workers (61 males and 20 females) have been occupationally exposed to benzene. In addition, 83 workers (55males and 28 females) were also recruited as a control group. Complete blood picture was analyzed and urinary t,t-MA was determined by liquid chromatography. In addition, creatinine in the urine samples was determined. Levels of blood elements (white blood cells, red blood cells and platelets) were decreased among exposed workers compared with the controls. The urinary level of t,t-MA/creatinine of the exposed workers was elevated especially in the smoking group compared to the controls. This study recommends that complete blood picture and t,t-MA are helpful biomarker tests that should be done to detect the early effects of benzene exposure.

  1. Investigation of the formation of physical damage on automotive finishes due to acidic reagent exposure

    SciTech Connect

    White, D.F.; Fornes, R.E.; Gilbert, R.D.; Speer, J.A. )

    1993-10-15

    Automotive paints with clear-coat surfaces can be physically damaged by exposure to acidic reagents produced in a smog chamber designed to reproduce real environmental conditions. Visual and reflectance microscopy observations show that deposition of material formed from the reaction of the clear coat and the reagent drop occurs on the paint surface after the drop evaporates to a critical size, with the greatest deposition occurring at the edge of the drop. This type of deposition suggests a free-energy minimization process favoring the formation of stable nuclei at the reagent drop edge. With heating after the drop evaporation to stimulate exposure to the sun, a damaged area containing sulfur that is in the shape of a circular ring is observed at the location of the deposits. The majority of the visual damage appears to result from an interaction between the deposit and the paint at elevated temperatures. Results from profilometry, scanning electron microscopy, and reflectance microscopy show that the damaged areas are ring-shaped cracked blisters on the surface resulting from the clear coat separating into layers.

  2. Butoxyethoxyacetic acid, a biomarker of exposure to water-based cleaning agents.

    PubMed

    Göen, Thomas; Korinth, Gintautas; Drexler, Hans

    2002-08-01

    The aim of the study was to investigate the suitability of butoxyethoxyacetic acid (BEAA) as a biomarker of exposure to water-based cleaning agents containing diethylene glycol mono butyl ether (DEGBE). The study was performed in two printing plants where water-based products containing 10-15% DEGBE were used for rubber and blanket washes. Thirty nine newspaper pressroom workers (exposed) and 19 employees of newspaper despatch departments (controls) were investigated. By questionnaire, the workers were asked about the use of personal protective measures. BEAA was determined in post-shift urine using GC-MS. The BEAA concentration in the urine of exposed workers ranged up to 75.1 mg/l (median 6.3 mg/l), whereas in urine samples of the controls the BEAA level was below or around the determination limit of 0.5 mg/l. A protective effect on DEGBE uptake was observed with the use of protective gloves. This observation implies that dermal penetration of DEGBE may be important in exposure monitoring. PMID:12191891

  3. Breast cancer risk after occupational solvent exposure: the influence of timing and setting.

    PubMed

    Ekenga, Christine C; Parks, Christine G; D'Aloisio, Aimee A; DeRoo, Lisa A; Sandler, Dale P

    2014-06-01

    Organic solvents are ubiquitous in occupational settings where they may contribute to risks for carcinogenesis. However, there is limited information on organic solvents as human breast carcinogens. We examined the relationship between occupational exposure to solvents and breast cancer in a prospective study of 47,661 women with an occupational history in the Sister Study cohort. Occupational solvent exposure was categorized using self-reported job-specific solvent use collected at baseline. Multivariable Cox regression analyses were used to assess breast cancer risk, adjusting for established breast cancer risk factors. A total of 1,798 women were diagnosed with breast cancer during follow-up, including 1,255 invasive cases. Overall the risk of invasive breast cancer was not associated with lifetime exposure to solvents [HR, 1.04; 95% confidence interval (CI), 0.88-1.24]. Parous women who worked with solvents before their first full-term birth had an increased risk of estrogen receptor-positive invasive breast cancer compared with women who never worked with solvents (HR, 1.39; 95% CI, 1.03-1.86). A significantly elevated risk for estrogen receptor-positive invasive breast cancer was associated with solvent exposure among clinical laboratory technologists and technicians (HR, 2.00; 95% CI, 1.07-3.73). Occupational exposure to solvents before first birth, a critical period of breast tissue differentiation, may result in increased vulnerability for breast cancer. Our findings suggest a need for future studies in this area to focus on exposure time windows and solvent types in different occupational settings.

  4. Breast cancer risk after occupational solvent exposure: the influence of timing and setting

    PubMed Central

    Ekenga, Christine C; Parks, Christine G.; D’Aloisio, Aimee A.; DeRoo, Lisa A.; Sandler, Dale P.

    2014-01-01

    Organic solvents are ubiquitous in occupational settings where they may contribute to risks for carcinogenesis. However, there is limited information on organic solvents as human breast carcinogens. We examined the relationship between occupational exposure to solvents and breast cancer in a prospective study of 47,661 women with an occupational history in the Sister Study cohort. Occupational solvent exposure was categorized using self-reported job-specific solvent use collected at baseline. Multivariable Cox regression analyses were used to assess breast cancer risk, adjusting for established breast cancer risk factors. A total of 1,798 women were diagnosed with breast cancer during follow-up, including 1,255 invasive cases. Overall, the risk of invasive breast cancer was not associated with lifetime exposure to solvents (HR: 1.04; 95% CI = 0.88–1.24). Parous women who worked with solvents prior to their first full-term birth had an increased risk of estrogen receptor-positive invasive breast cancer compared to women who never worked with solvents (HR: 1.39; 95% CI = 1.03–1.86). A significantly elevated risk for estrogen receptor-positive invasive breast cancer was associated with solvent exposure among clinical laboratory technologists and technicians (HR: 2.00; 95%CI: 1.07–3.73). Occupational exposure to solvents prior to first birth, a critical period of breast tissue differentiation, may result in increased vulnerability for breast cancer. Our findings suggest a need for future studies in this area to focus on exposure time windows and solvent types in different occupational settings. PMID:24879566

  5. Central and Peripheral Timing Variability in Children with Heavy Prenatal Alcohol Exposure

    PubMed Central

    Simmons, Roger W.; Levy, Susan S.; Riley, Edward P.; Madra, Naju M.; Mattson, Sarah N.

    2008-01-01

    Background The study examined whether prenatal alcohol exposure is associated with increased motor timing variability when the timing response is partitioned into central clock variability, which indexes information processing at the central nervous system (CNS) level and motor delay variability, which reflects timing processes at the level of the peripheral nervous system (PNS). Methods Eighteen children with histories of prenatal alcohol exposure and 22 control children were assigned to young (7–11 years) or older (12–17 years) groups. Children tapped a single response key with the index finger in synchrony with a series of externally generated tones (the paced phase). At the conclusion of these tones, children continued tapping (the continuation phase) while attempting to maintain the same rate of tapping imposed by the paced phase. Two blocks of tapping were completed with inter-tone-intervals set at either 400 or 900 ms. Inter-response interval, central clock variability, and motor delay variability produced during the continuation phase were the dependent variables. Results Mean inter-response interval for the four groups did not differ for either time interval. Central clock variability produced by the young alcohol-exposed group was significantly greater than the two older groups for the 400 ms interval and all other groups for the 900 ms interval. Motor delay variability produced by the young alcohol-exposed group was significantly greater than the other three groups for both time intervals. Central and motor delay variability in children with and without alcohol exposure was directly related to the duration of the interval to be reproduced. Conclusions Central and peripheral timing variability was significantly greater for the young alcohol-exposed children. This atypical timing may be related to the teratogenic effects of alcohol, although the negative effects are limited to younger alcohol-exposed children since there were no differences in central

  6. Effects of exposure time during flight maneuvers on passenger subjective comfort rating

    NASA Technical Reports Server (NTRS)

    Brown, V. J.

    1975-01-01

    The effects were investigated of length of exposure time to a flight maneuver environment on subjective passenger evaluation of ride comfort. Four statistical analysis tests were performed on ride comfort ratings obtained during one two-hour test flight wherein eleven test subjects were exposed to two identical programmed sequences of twenty four flight segments which covered a wide range of maneuver conditions. The results of the analysis indicate that, for over ninety five percent of the segments, there is no significant change in the test subjects comfort ratings of identical segments spaced one hour apart. These results are in contrast to those found in previous studies involving a vibration environment, rather than flight maneuver environment, where increased exposure-time was found to cause a degradation of ride comfort ratings.

  7. Lysis of Chlamydomonas reinhardtii by high-intensity focused ultrasound as a function of exposure time.

    PubMed

    Bigelow, Timothy A; Xu, Jin; Stessman, Dan J; Yao, Linxing; Spalding, Martin H; Wang, Tong

    2014-05-01

    Efficient lysis of microalgae for lipid extraction is an important concern when processing biofuels. Historically, ultrasound frequencies in the range of 10-40 kHz have been utilized for this task. However, greater efficiencies might be achievable if higher frequencies could be used. In our study, we evaluated the potential of using 1.1 MHz ultrasound to lyse microalgae for biofuel production while using Chlamydomonas reinhardtii as a model organism. The ultrasound was generated using a spherically focused transducer with a focal length of 6.34 cm and an active diameter of 6.36 cm driven by 20 cycle sine-wave tone bursts at a pulse repetition frequency of 2 kHz (3.6% duty cycle). The time-average acoustic power output was 26.2 W while the spatial-peak-pulse-average intensity (ISPPA) for each tone burst was 41 kW/cm(2). The peak compressional and rarefactional pressures at the focus were 102 and 17 MPa, respectively. The exposure time was varied for the different cases in the experiments from 5s to 9 min and cell lysis was assessed by quantifying the percentage of protein and chlorophyll release into the supernate as well as the lipid extractability. Free radical generation and lipid oxidation for the different ultrasound exposures were also determined. We found that there was a statistically significant increase in lipid extractability for all of the exposures compared to the control. The longer exposures also completely fragmented the cells releasing almost all of the protein and chlorophyll into the supernate. The cavitation activity did not significantly increase lipid oxidation while there was a minor trend of increased free radical production with increased ultrasound exposure.

  8. Visualisation of blood and lymphatic vessels with increasing exposure time of the detector

    NASA Astrophysics Data System (ADS)

    Kalchenko, V. V.; Kuznetsov, Yu L.; Meglinski, I. V.

    2013-07-01

    We describe the laser speckle contrast method for simultaneous noninvasive imaging of blood and lymphatic vessels of living organisms, based on increasing detector exposure time. In contrast to standard methods of fluorescent angiography, this technique of vascular bed imaging and lymphatic and blood vessel demarcation does not employ toxic fluorescent markers. The method is particularly promising with respect to the physiology of the cardiovascular system under in vivo conditions.

  9. Visualisation of blood and lymphatic vessels with increasing exposure time of the detector

    SciTech Connect

    Kalchenko, V V; Kuznetsov, Yu L; Meglinski, I V

    2013-07-31

    We describe the laser speckle contrast method for simultaneous noninvasive imaging of blood and lymphatic vessels of living organisms, based on increasing detector exposure time. In contrast to standard methods of fluorescent angiography, this technique of vascular bed imaging and lymphatic and blood vessel demarcation does not employ toxic fluorescent markers. The method is particularly promising with respect to the physiology of the cardiovascular system under in vivo conditions. (laser applications in biology and medicine)

  10. Exposure to chemical cocktails before or after conception – The effect of timing on ovarian development☆

    PubMed Central

    Bellingham, Michelle; Amezaga, Maria R.; Mandon-Pepin, Beatrice; Speers, Christopher J.B.; Kyle, Carol E.; Evans, Neil P.; Sharpe, Richard M.; Cotinot, Corinne; Rhind, Stewart M.; Fowler, Paul A.

    2013-01-01

    Exposure of female fetuses to environmental chemicals (ECs) during pregnancy results in a disturbed ovarian adult phenotype. We investigated the influence of pre- and/or post-conception exposure to low-level mixtures of ECs on the structure and function of the fetal ovine ovary. We examined ovarian morphology, expression of oocyte and granulosa cell-specific genes and proteome. Female fetuses were collected at day 110 of gestation, from dams exposed continuously until, and after mating, by grazing in pastures treated with sewage sludge as a fertiliser (TT) or in control fields treated with inorganic fertiliser (CC). In addition, in a cross-over design, fetal ovaries were collected from dams maintained on sludge pastures up to the time of mating but then transferred to control pastures (TC) and, reciprocally, those transferred from control to treated pastures at mating (CT). On examination, the proportion of type 1a follicles (activating primordial follicles) was significantly lower in animals from the CT groups compared with CC and TT groups (P < 0.05). Of the 23 ovarian gene transcripts studied, 14 were altered in the ovaries of exposed fetuses (CT, TC, and TT) relative to controls, with the largest number of changes observed in cross-exposure pattern groups (CT or TC). Continuous EC exposure (TT) produced fewer transcript alterations and only two genes (INHBA and GSN) presented differential profiles between CC and TT. Fetal ovarian proteome analysis (2-DE gels) showed, across all exposure groups, 86 differentially expressed protein spots compared to controls. Animals in the CT group exhibited the highest number (53) while TC and TT presented the same number of affected protein spots (42). Fetal ovarian proteins with altered expression included MVP (major vault protein) and several members of the heat-shock family (HSPA4L, HSP90AA1 and HSF1). The present findings indicate that continuous maternal EC exposure before and during gestation, are less deleterious for

  11. Exposure to domoic acid affects larval development of king scallop Pecten maximus (Linnaeus, 1758).

    PubMed

    Liu, Hui; Kelly, Maeve S; Campbell, Dirk A; Dong, Shuang Lin; Zhu, Jian Xin; Wang, Su Feng

    2007-02-28

    Domoic acid (DA) is a highly toxic phycotoxin produced by bloom forming marine diatoms Pseudo-nitzschia spp. Bivalves can accumulate this toxin to a high level through their feeding activities, and thus illness or death in can occur in consumers of bivalves. In this study, king scallop, Pecten maximus, larvae were exposed to dissolved domoic acid (DA) for 25d, and the toxin accumulation and effects of harbouring this toxin were investigated. Scallop larvae incorporated DA continuously during the larval culture period and accumulated a maximum DA level of 5.21pgind(-1) when exposed to a solution of 50ngml(-1) dissolved DA. As a result of the DA treatment, larval growth, measured in terms of shell length and the appearance of the eye-spot, and larval survival were significantly compromised. This is the first study on DA incorporation dynamics in P. maximus larvae, signifying the potential of using shellfish larvae for the study on mechanisms of phycotoxin accumulation. The negative effect of DA exposure suggests that this toxin could possibly influence natural recruitment in P. maximus, and it may be necessary to protect hatchery-cultured scallop larvae from DA during toxic Pseudo-nitzschia blooms.

  12. Effect of deployment time on endotoxin and allergen exposure assessment using electrostatic dust collectors.

    PubMed

    Kilburg-Basnyat, Brita; Metwali, Nervana; Thorne, Peter S

    2015-01-01

    The electrostatic dust collector (EDC) is a passive dust sampling device for exposure assessment of airborne endotoxin and possibly allergens. EDCs consist of a non-conducting plastic folder holding two or four electrostatic cloths of defined area. The sampling time needed to achieve detectable and reproducible loading for bioaerosols has not been systematically evaluated. Thus, in 15 Iowa farm homes EDCs were deployed for 7-, 14-, and 28-day sampling periods to determine if endotoxin and allergens could be quantified and if loading rates were uniform over time, i.e. if loads doubled from 7 to 14 days or 14 to 28 days and quadrupled from 7 to 28 days. Loadings between left and right paired EDC cloths were not significantly different and were highly correlated for endotoxin, total protein, and cat (Fel d1), dog (Can f1), and mouse (Mus m1) allergens (P < 0.001). EDCs performed especially well for endotoxin sampling with close agreement between paired samples (Pearson r = 0.96, P < 0.001). Endotoxin loading of the EDCs doubled from 7- to 14-day deployments as hypothesized although the loading rate decreased from 14 to 28 days of sampling with only a 1.38-fold increase. Allergen exposure assessment using EDCs was overall less satisfactory. Although there was reasonable agreement between paired samples, only exposures to cat, dog, and mouse allergens were reliable and these only at the longer deployment times.

  13. a Solution to Low Rfm Fitting Precision of Planetary Orbiter Images Caused by Exposure Time Changing

    NASA Astrophysics Data System (ADS)

    Liu, B.; Xu, B.; Di, K.; Jia, M.

    2016-06-01

    In this paper, we propose a new solution to the low RFM fitting precision caused by exposure time changing using sensor correction. First, we establish a new rigorous geometric model, with the same ephemerides, attitudes and sensor design parameters of Chang'E-2 and HRSC images, using an equal exposure time of each scan line. The original rigorous geometric model is also established. With a given height, we can establish the correspondence between the two rigorous models. Then we generate a sensor corrected image by resampling the original image using an average elevation or a digital elevation model. We found that the sensor corrected images can be used for topographic mapping which maintains almost the same precision of the original images under certain conditions. And RFM can fit rigorous geometric model of the sensor corrected image very well. Preliminary experimental results show that the RMS residual error of the RFM fitting can reach to 1/100 pixel level too. Using the proposed solution, sensors with changing exposure time can be precisely modelled by the generic RFM.

  14. Stellar scintillation in the short exposure regime and atmospheric coherence time evaluation

    NASA Astrophysics Data System (ADS)

    Kornilov, V.

    2011-06-01

    Aims: Accurately measuring the atmospheric coherence time is still a significant problem despite a variety of applicable methods. The Multi-Aperture Scintillation Sensor (MASS) designed for the vertical profiling of optical turbulence also provides a measurements of coherence time, but its results were found to be biased. Hence there is a need for a more robust method to determine τ0. Methods: The effect of smoothing the stellar scintillation by a finite exposure of the detector is considered. The short exposure regime is described and its limits are defined. The re-analysis of previous measurements with the MASS is performed to test the applicability of this approach in real data processing. It is shown that most of the actual measurements satisfy the criteria of short exposures. Results: The expressions for the mean wind speeds bar V_2 in the free atmosphere from the measurement of the scintillation indices are derived for this regime. These values provide an estimate of the atmospheric coherence time τ0 without the need of empirical calibration. The verification of the method based on real measurements of the resulting τ0 agree well with independent methods.

  15. The Effect of Perfluorooctane Sulfonate, Exposure Time, and Chemical Mixtures on Methanogenic Community Structure and Function

    PubMed Central

    McNamara, Patrick J; LaPara, Timothy M; Novak, Paige J

    2015-01-01

    A plethora of organic micropollutant mixtures are found in untreated municipal wastewater. Anaerobic digesters receive large loadings of hydrophobic micropollutants that sorb to wastewater biosolids. Despite micropollutants being pervasive as mixtures, little research is available to explain the impact that mixtures of compounds, as well as exposure time, have on microbial communities in anaerobic digesters. Perfluorooctane sulfonate (PFOS) was added to anaerobic enrichment cultures in both short-term (14 days) and long-term (140 days) studies to determine the impact of exposure time. Additionally, triclosan was added during the experiments to investigate the impact of mixtures on community structure and function. PFOS did not alter methane production in short-term studies, but in long-term studies, methane production increased, consistent with our hypothesis that PFOS may act as a metabolic uncoupler. The impact of triclosan on methane production was exacerbated when PFOS was already present in the anaerobic enrichment cultures. Triclosan also had greater impacts on microbial community structures in the bottles that had been exposed to PFOS long-term. These results demonstrate that both chemical mixtures and exposure time are important parameters to address when trying to define the impacts of micropollutants on anaerobic microbial communities. PMID:26462249

  16. Effect of Deployment Time on Endotoxin and Allergen Exposure Assessment Using Electrostatic Dust Collectors

    PubMed Central

    Kilburg-Basnyat, Brita; Metwali, Nervana; Thorne, Peter S.

    2015-01-01

    The electrostatic dust collector (EDC) is a passive dust sampling device for exposure assessment of airborne endotoxin and possibly allergens. EDCs consist of a non-conducting plastic folder holding two or four electrostatic cloths of defined area. The sampling time needed to achieve detectable and reproducible loading for bioaerosols has not been systematically evaluated. Thus, in 15 Iowa farm homes EDCs were deployed for 7-, 14-, and 28-day sampling periods to determine if endotoxin and allergens could be quantified and if loading rates were uniform over time, i.e. if loads doubled from 7 to 14 days or 14 to 28 days and quadrupled from 7 to 28 days. Loadings between left and right paired EDC cloths were not significantly different and were highly correlated for endotoxin, total protein, and cat (Fel d1), dog (Can f1), and mouse (Mus m1) allergens (P < 0.001). EDCs performed especially well for endotoxin sampling with close agreement between paired samples (Pearson r = 0.96, P < 0.001). Endotoxin loading of the EDCs doubled from 7- to 14-day deployments as hypothesized although the loading rate decreased from 14 to 28 days of sampling with only a 1.38-fold increase. Allergen exposure assessment using EDCs was overall less satisfactory. Although there was reasonable agreement between paired samples, only exposures to cat, dog, and mouse allergens were reliable and these only at the longer deployment times. PMID:25187036

  17. The Effect of Perfluorooctane Sulfonate, Exposure Time, and Chemical Mixtures on Methanogenic Community Structure and Function.

    PubMed

    McNamara, Patrick J; LaPara, Timothy M; Novak, Paige J

    2015-01-01

    A plethora of organic micropollutant mixtures are found in untreated municipal wastewater. Anaerobic digesters receive large loadings of hydrophobic micropollutants that sorb to wastewater biosolids. Despite micropollutants being pervasive as mixtures, little research is available to explain the impact that mixtures of compounds, as well as exposure time, have on microbial communities in anaerobic digesters. Perfluorooctane sulfonate (PFOS) was added to anaerobic enrichment cultures in both short-term (14 days) and long-term (140 days) studies to determine the impact of exposure time. Additionally, triclosan was added during the experiments to investigate the impact of mixtures on community structure and function. PFOS did not alter methane production in short-term studies, but in long-term studies, methane production increased, consistent with our hypothesis that PFOS may act as a metabolic uncoupler. The impact of triclosan on methane production was exacerbated when PFOS was already present in the anaerobic enrichment cultures. Triclosan also had greater impacts on microbial community structures in the bottles that had been exposed to PFOS long-term. These results demonstrate that both chemical mixtures and exposure time are important parameters to address when trying to define the impacts of micropollutants on anaerobic microbial communities. PMID:26462249

  18. Real-time measurement of dust in the workplace using video exposure monitoring: Farming to pharmaceuticals

    NASA Astrophysics Data System (ADS)

    Walsh, P. T.; Forth, A. R.; Clark, R. D. R.; Dowker, K. P.; Thorpe, A.

    2009-02-01

    Real-time, photometric, portable dust monitors have been employed for video exposure monitoring (VEM) to measure and highlight dust levels generated by work activities, illustrate dust control techniques, and demonstrate good practice. Two workplaces, presenting different challenges for measurement, were used to illustrate the capabilities of VEM: (a) poultry farming activities and (b) powder transfer operations in a pharmaceutical company. For the poultry farm work, the real-time monitors were calibrated with respect to the respirable and inhalable dust concentrations using cyclone and IOM reference samplers respectively. Different rankings of exposure for typical activities were found on the small farm studied here compared to previous exposure measurements at larger poultry farms: these were mainly attributed to the different scales of operation. Large variations in the ratios of respirable, inhalable and real-time monitor TWA concentrations of poultry farm dust for various activities were found. This has implications for the calibration of light-scattering dust monitors with respect to inhalable dust concentration. In the pharmaceutical application, the effectiveness of a curtain barrier for dust control when dispensing powder in a downflow booth was rapidly demonstrated.

  19. Timing of Environmental Exposures as a Critical Element in Breast Cancer Risk

    PubMed Central

    Birnbaum, Linda S.

    2015-01-01

    Objective: The role of the chemical environment in disease initiation or progression is becoming more evident. Endocrine disruption via environmental chemicals is now well documented in humans, rodent research models, and wildlife. Breast cancer is an endocrine-based disease whose risk may be modified by environmental exposures. Our purpose is to encourage more investigation into early life environmental exposures as they relate to breast cancer risk factors and disease over a lifetime. Evidence: The 2009 President's Cancer Panel, 2012 Institute of Medicine, 2013 Interagency Breast Cancer and the Environment Research Coordinating Committee reports, and research publications dated ≥2012 in PubMed were used to inform our perspective. Consensus Process: Literature was reviewed and evidence gathered on the effects of the environment on risk of breast cancer or mammary tumor development in animal research models as it pertained to the influence of timing of exposure on later-life outcomes. Conclusions: Evidence has accumulated for several chemicals that environmental factors have a stronger effect on breast cancer risk when exposure occurred early in life. The insecticide, dichlorodiphenyltrichloroethane, is an excellent example and is just one of several chemicals for which there seems to be both animal and human evidence for the developmental basis of adult disease. The developing breast undergoes many changes in early life, leaving it vulnerable to the effects of epigenetic marks, endocrine disruption, and carcinogens. More research is needed in the area of early beginnings of breast cancer, with prevention of the disease as the ultimate goal. PMID:26214118

  20. Microgravity Inhibits Resting T Cell Immunity in an Exposure Time-Dependent Manner

    PubMed Central

    Luo, Haiying; Wang, Chongzhen; Feng, Meifu; Zhao, Yong

    2014-01-01

    Background: Decline immune function is well documented after spaceflights. Microgravity is one of the key factors directly suppressing the function of immune system. Though T cell immune response was inhibited by microgravity, it is not clearly whether activation would be inhibited after a pre-exposure of microgravity on T lymphocytes at the resting state. Methods: We herein investigated the response ability of resting CD4+ and CD8+ T cells experiencing pre-exposure of modeled microgravity (MMg) for 0, 8, 16 and 24 hrs to concanavalin A (ConA) stimulation. The phenotypes and subsets of immune cells were determined by flow cytometry. Results: Both CD4+ and CD8+ T cells with an MMg pre-exposure exhibited decreased expressions of activation-markers including CD25, CD69 and CD71, inflammatory cytokine secretion and cell proliferation in response to ConA compared with T cells with 1g controls in an MMg exposure time- dependent manner. Moreover, short term MMg treatment caused more severe decreased proliferation in CD4+ T cells than in CD8+ T cells. Conclusions: MMg can directly impact on resting T cell subsets. CD4+ T cells were more sensitive to the microgravity inhibition than CD8+ T cells in respect of cell proliferation. These results offered new insights for the MMg-caused T cell functional defects. PMID:24396290

  1. The effect of short-time microwave exposures on Listeria monocytogenes inoculated onto chicken meat portions

    PubMed Central

    Zeinali, Tayebeh; Jamshidi, Abdollah; Khanzadi, Saeid; Azizzadeh, Mohammad

    2015-01-01

    Listeria monocytogenes can be found throughout the environment and in many foods. It is associated primarily with meat and animal products. Listeria monocytogenes has become increasingly important as a food-borne pathogen. The aim of this study was to evaluate the effect of microwave (MW) treatment of chicken meat samples which were inoculated with L. monocytogenes. Drumettes of broiler carcasses were soaked in fully growth of L. monocytogenes in Brain-Heart Infusion broth. The swab samples were taken from the inoculated samples, after various times of radiation (10, 20, 30, 40, 50, 60, 70 and 80 sec), using a domestic MW oven at full power. Following exposures, viable counts and surface temperature measurements were performed. The bacterial counts were performed on Oxford agar. The results indicated that equal or longer than 60 sec exposures of chicken portions to MW heating which enhances the median surface temperature more than 74 ˚C could eliminate the superficial contamination of chicken meat with L. monocytogenes. Statistical analysis showed samples with equal or longer than 60 sec exposures to MW heating had significant decrease in population of inoculated bacteria compared with positive control group (p < 0.05). Pearson correlation showed a significant correlation between the bacterial population and temperature of samples due to MW exposure (p < 0.001, r = – 0.879 and r2 = 0.773). PMID:26261715

  2. Glyphosate spray drift in Coffea arabica - sensitivity of coffee plants and possible use of shikimic acid as a biomarker for glyphosate exposure.

    PubMed

    Schrübbers, Lars C; Valverde, Bernal E; Sørensen, Jens C; Cedergreen, Nina

    2014-10-01

    Glyphosate is widely used in coffee plantations to control weeds. Lacking selectivity, glyphosate spray drift is suspected to cause adverse effects in coffee plants. Symptoms caused by glyphosate can be similar to those produced by other stress factors. However, shikimic acid accumulation should be a useful biomarker for glyphosate exposure as shown for other crops. The aim of this study was to assess the sensitivity of coffee plants towards glyphosate on different biological response variables and to evaluate the use of shikimic acid as biomarker. Dose-response experiments yielded ED50 values (50% effect dose) in the range of 38-550 ga.e.ha(-1) depending on the quantitative or qualitative variable monitored. The frequency of plants showing symptoms was the most sensitive variable. The best sampling time for shikimic acid accumulation was 1-2 weeks after glyphosate application, depending on experimental conditions. The highest shikimic acid accumulation was observed in young leaves. Shikimic acid is a suitable biomarker for a glyphosate exposure in coffee, using only young leaves for the analysis. Young coffee plants are susceptible to glyphosate damage. If symptoms are absent the risk of severe crop damage or yield loss is low. PMID:25307461

  3. Determining Phthalic Acid Esters Using Terahertz Time Domain Spectroscopy

    NASA Astrophysics Data System (ADS)

    Liu, L.; Shen, L.; Yang, F.; Han, F.; Hu, P.; Song, M.

    2016-09-01

    In this report terahertz time domain spectroscopy (THz-TDS) is applied for determining phthalic acid esters (PAEs) in standard materials. We reported the THz transmission spectrum in the frequency range of 0.2 to 2.0 THz for three PAEs: di-n-butyl phthalate (DBP), di-isononyl phthalate (DINP), and di-2-ethylhexyl phthalate ester (DEHP). The study provided the refractive indices and absorption features of these materials. The absorption spectra of three PAEs were simulated by using Gaussian software with Density Functional Theory (DFT) methods. For pure standard PAEs, the values of the refractive indices changed between 1.50 and 1.60. At 1.0 THz, the refractive indices were 1.524, 1.535, and 1.563 for DINP, DEHP, and DBP, respectively. In this experiment different concentrations of DBP were investigated using THz-TDS. Changes were measured in the low THz frequency range for refractive indices and characteristic absorption. The results indicated that THz-TDS is promising as a new method in determining PAEs in many materials. The results of this study could be used to support the practical application of THz-TDS in quality detection and food monitoring. In particular, this new technique could be used in detecting hazardous materials and other substances present in wine or foods.

  4. The effect of local mild cold exposure on pulse transit time.

    PubMed

    Zhang, Xin-Yu; Zhang, Yuan-Ting

    2006-07-01

    Pulse transit time (PTT) is a simple, noninvasive technique which shows great promise in the continuous monitoring of blood pressure and the assessment of arterial stiffness, and has potential applications in wearable healthcare devices. Usually, PTT is measured from the electrocardiogram (ECG) R-wave to a characteristic point on the peripheral pulse by photoplethysmography. However, peripheral blood circulation is sensitive to local temperature variation. This study investigated the effect of mild cold exposure on PTT by immersing one finger into cold water. The photoplethysmographic (PPG) signals were recorded from the cooled and adjacent uncooled fingers. The significant change in dc and ac amplitudes of the PPG pulse indicates that the mild cold exposure has a substantial effect on finger blood circulation. Three measurements of PTT were performed by calculating the time delay from the ECG R-wave to three different characteristic points on the PPG pulse, namely, the foot (PTT1), the point on the rising limb with maximal slope (PTT2) and the peak (PTT3), respectively. PTT3 was found to be easily subject to waveform distortion. Significant changes in the difference of PTT1 and PTT2 between two fingers were observed after a 5 min recovery period. The changes in PTT1 and PTT2 on the reference finger also showed close correlation (r = -0.77 and r = -0.80, p < 0.001) with the changes in SBP after recovery, whereas those measured on the test finger have low correlation (r = -0.53 and r = -0.38, p > 0.15). The results suggest that mild cold exposure may have a delay effect on PTT due to cold-induced vasodilatation and could be a potential source of error. The effect of cold exposure should be carefully examined, especially when PTT that includes a large portion of rising time of peripheral pulse is applied.

  5. Role of Concentration and Time of Day in Developing Ozone Exposure Indices for a Secondary Standard.

    PubMed

    Lee, E H; Hogsett, W E

    1999-06-01

    Evidence from exposure-response studies and a turbulent transfer model demonstrate that plant response is differential to concentration, duration, temporal pattern, and time of day of exposure. Reductions in productivity of crops and trees as seedlings are greater when plants are exposed to higher daytime ozone (O3) concentrations (0800-2000 hr standard time) or for longer durations. Primary evidence on the greater role of concentration comes from exposure-response experiments where plants are exposed to a series of pollutant concentrations in open-top chambers under field conditions. These studies demonstrate that the integrated exposure indices that give preferential weight to higher concentrations are better predictors of response than mean or peak indices. Evidence suggesting that mid-range O3 concentrations (0.05-0.09 parts per million, ppm) play a greater role than higher concentrations (>0.09 ppm) in biological response could not be justified. The time of day when O3 concentrations and atmospheric and stomatal conductances of gas exchange are optimal is a key to understanding plant response because plants respond only to O3 entering the leaf via stomata. A turbulent transfer model that describes the resistance of pollutant gas exchange from the atmosphere to the boundary layer of a forest canopy, as a function of micrometeorological variables, is developed to determine when flux of O3 is optimal. Based on meteorological and ambient air quality monitoring data at remote forest sites in the United States, it appears that O3 flux densities to the forest boundary layer are optimal during the 0800-2000 hr window. It is concluded that descriptors of ambient air quality for use in setting a federal standard should (1) cumulate hourly O3 concentrations, (2) give preferential weight to daytime concentrations between 0800 and 2000 hr, and (3) give preferential weight to higher O3 concentrations.

  6. Influence of the degree of exposure to lead on relations between alcohol consumption and the biological indices of lead exposure: epidemiological study in a lead acid battery factory.

    PubMed Central

    Cezard, C; Demarquilly, C; Boniface, M; Haguenoer, J M

    1992-01-01

    Alcohol has been shown to interact with lead to influence haem biosynthesis. The aim of this study was to define the dependence of this interaction on the degree of exposure to lead. Exposure to alcohol was estimated by measurement of alcohol concentrations in a sample of urine collected during the morning (AlcUM) (0.82 (SD 4.36) mmol/l) and in a sample collected during the afternoon (AlcUA) (1.15 (SD 3.49) mmol/l). The biological monitoring of exposure to lead included measurements of blood lead (Pb-B) (1.82 (SD 0.72) mumol/l), urinary delta-aminolaevulinic acid (ALAU) (35.33 (SD 28.00) mumol/l; d = 1.015), and erythrocyte zinc-protoporphyrin (ZPP) (112.90 (SD 83.71) nmol/mmol Hb) concentrations. The study of the influence of the degree of occupational exposure to lead on relations between alcohol consumption and effects of the exposure to lead led to the consideration of two different groups--namely, mildly and strongly exposed subjects. In the first group, individual biological susceptibility seemed to play a preponderant part. In the second, the pool of lead present in the body seemed to be sufficiently important to mask the effects of individual susceptibility. PMID:1390270

  7. Influence of the degree of exposure to lead on relations between alcohol consumption and the biological indices of lead exposure: epidemiological study in a lead acid battery factory.

    PubMed

    Cezard, C; Demarquilly, C; Boniface, M; Haguenoer, J M

    1992-09-01

    Alcohol has been shown to interact with lead to influence haem biosynthesis. The aim of this study was to define the dependence of this interaction on the degree of exposure to lead. Exposure to alcohol was estimated by measurement of alcohol concentrations in a sample of urine collected during the morning (AlcUM) (0.82 (SD 4.36) mmol/l) and in a sample collected during the afternoon (AlcUA) (1.15 (SD 3.49) mmol/l). The biological monitoring of exposure to lead included measurements of blood lead (Pb-B) (1.82 (SD 0.72) mumol/l), urinary delta-aminolaevulinic acid (ALAU) (35.33 (SD 28.00) mumol/l; d = 1.015), and erythrocyte zinc-protoporphyrin (ZPP) (112.90 (SD 83.71) nmol/mmol Hb) concentrations. The study of the influence of the degree of occupational exposure to lead on relations between alcohol consumption and effects of the exposure to lead led to the consideration of two different groups--namely, mildly and strongly exposed subjects. In the first group, individual biological susceptibility seemed to play a preponderant part. In the second, the pool of lead present in the body seemed to be sufficiently important to mask the effects of individual susceptibility.

  8. Estimating volatile organic compound concentrations in selected microenvironments using time-activity and personal exposure data.

    PubMed

    Sexton, Ken; Mongin, Steven J; Adgate, John L; Pratt, Gregory C; Ramachandran, Gurumurthy; Stock, Thomas H; Morandi, Maria T

    2007-03-01

    Repeated measures of personal exposure to 14 volatile organic compounds (VOC) were obtained over 3 seasons for 70 healthy, nonsmoking adults living in Minneapolis-St. Paul. Matched data were also available for participants' time-activity patterns, and measured VOC concentrations outdoors in the community and indoors in residences. A novel modeling approach employing hierarchical Bayesian techniques was used to estimate VOC concentrations (posterior mode) and variability (credible intervals) in five microenvironments: (1) indoors at home; (2) indoors at work/school; (3) indoors in other locations; (4) outdoors in any location; and (5) in transit. Estimated concentrations tended to be highest in "other" indoor microenvironments (e.g., grocery stores, restaurants, shopping malls), intermediate in the indoor work/school and residential microenvironments, and lowest in the outside and in-transit microenvironments. Model estimates for all 14 VOC were reasonable approximations of measured median concentrations in the indoor residential microenvironment. The largest predicted contributor to cumulative (2-day) personal exposure for all 14 VOC was the indoor residential environment. Model-based results suggest that indoors-at-work/school and indoors-at-other-location microenvironments were the second or third largest contributors for all VOC, while the outside-in-any-location and in-transit microenvironments appeared to contribute negligibly to cumulative personal exposure. Results from a mixed-effects model indicate that being in or near a garage increased personal exposure to o-xylene, m/p-xylene, benzene, ethylbenzene, and toluene, and leaving windows and doors at home open for 6 h or more decreased personal exposure to 13 of 14 VOC, all except trichloroethylene.

  9. Variation in voxel value distribution and effect of time between exposures in six CBCT units.

    PubMed

    Spin-Neto, R; Gotfredsen, E; Wenzel, A

    2014-01-01

    The aim of this study is to assess the variation in voxel value distribution in volumetric data sets obtained by six cone beam CT (CBCT) units, and the effect of time between exposures. Six CBCT units [Cranex(®) 3D (CRAN; Soredex Oy, Tuusula, Finland), Scanora(®) 3D (SCAN; Soredex Oy), NewTom™ 5G (NEWT; QR Srl, Verona, Italy), Promax(®) Dimax 3 (Planmeca Oy, Helsinki, Finland), i-CAT (Imaging Sciences International, Hatfield, PA) and 3D Accuitomo FPD80 (Morita, Kyoto, Japan)] were tested. Two volumetric data sets of a dry human skull embedded in acrylic were acquired by each CBCT unit in two sessions on separate days. Each session consisted of 20 exposures: 10 acquired with 30 min between exposures and 10 acquired immediately one after the other. CBCT data were exported as digital imaging and communications in medicine (DICOM) files and converted to text files. The text files were re-organized to contain x-, y- and z-position and grey shade for each voxel. The files were merged to contain 1 record per voxel position, including the voxel values from the 20 exposures in a session. For each voxel, subtractions were performed between Data Set 1 and the remaining 19 data sets (1 - 2, 1 - 3, etc) in a session. Means, medians, ranges and standard deviations for grey shade variation in the subtraction data sets were calculated for each unit and session. For all CBCT units, variation in voxel values was observed throughout the 20 exposures. A "fingerprint" for the grey shade variation was observed for CRAN, SCAN and NEWT. For the other units, the variation was (apparently) randomly distributed. Large discrepancies in voxel value distribution are seen in CBCT images. This variation should be considered in studies that assess minute changes in CBCT images. PMID:24678846

  10. Variation in voxel value distribution and effect of time between exposures in six CBCT units

    PubMed Central

    Gotfredsen, E; Wenzel, A

    2014-01-01

    The aim of this study is to assess the variation in voxel value distribution in volumetric data sets obtained by six cone beam CT (CBCT) units, and the effect of time between exposures. Six CBCT units [Cranex® 3D (CRAN; Soredex Oy, Tuusula, Finland), Scanora® 3D (SCAN; Soredex Oy), NewTom™ 5G (NEWT; QR Srl, Verona, Italy), Promax® Dimax 3 (Planmeca Oy, Helsinki, Finland), i-CAT (Imaging Sciences International, Hatfield, PA) and 3D Accuitomo FPD80 (Morita, Kyoto, Japan)] were tested. Two volumetric data sets of a dry human skull embedded in acrylic were acquired by each CBCT unit in two sessions on separate days. Each session consisted of 20 exposures: 10 acquired with 30 min between exposures and 10 acquired immediately one after the other. CBCT data were exported as digital imaging and communications in medicine (DICOM) files and converted to text files. The text files were re-organized to contain x-, y- and z-position and grey shade for each voxel. The files were merged to contain 1 record per voxel position, including the voxel values from the 20 exposures in a session. For each voxel, subtractions were performed between Data Set 1 and the remaining 19 data sets (1 − 2, 1 − 3, etc) in a session. Means, medians, ranges and standard deviations for grey shade variation in the subtraction data sets were calculated for each unit and session. For all CBCT units, variation in voxel values was observed throughout the 20 exposures. A “fingerprint” for the grey shade variation was observed for CRAN, SCAN and NEWT. For the other units, the variation was (apparently) randomly distributed. Large discrepancies in voxel value distribution are seen in CBCT images. This variation should be considered in studies that assess minute changes in CBCT images. PMID:24678846

  11. Incidence of mesothelioma in Lombardy, Italy: exposure to asbestos, time patterns and future projections

    PubMed Central

    Mensi, Carolina; De Matteis, Sara; Dallari, Barbara; Riboldi, Luciano; Bertazzi, Pier Alberto; Consonni, Dario

    2016-01-01

    Objectives In Italy, asbestos has been extensively used from 1945 to 1992. We evaluated the impact of exposure to asbestos on occurrence of malignant mesothelioma (MM) in the Lombardy Region, Northwest Italy, the most populated and industrialised Italian region. Methods From the Lombardy Mesothelioma Registry, we selected all incident cases of MM diagnosed between 2000 and 2012. We described sources of exposure to asbestos and examined time trends of MM rates. Using Poisson age-cohort models, we derived projections of burden of MM in the Lombardy population for the period 2013–2029. Results In 2000–2012, we recorded 4442 cases of MM (2850 men, 1592 women). Occupational exposure to asbestos was more frequent in men (73.6%) than in women (38.2%). Non-occupational exposure was found for 13.6% of women and 3.6% of men. The average number of cases of MM per year was still increasing (+3.6% in men, +3.3% in women). Incidence rates were still increasing in individuals aged 65+ years and declining in younger people. A maximum of 417 cases of MM (267 men, 150 women) are expected in 2019. We forecast there will be 6832 more cases (4397 in men, 2435 in women) in the period 2013–2029, for a total of 11 274 cases of MM (7247 in men, 4027 in women) in 30 years. Conclusions This study documented a high burden of MM in both genders in the Lombardy Region, reflecting extensive occupational (mainly in men) and non-occupational (mainly in women) exposure to asbestos in the past. Incidence rates are still increasing; a downturn in occurrence of MM is expected to occur after 2019. PMID:27312399

  12. Variation in voxel value distribution and effect of time between exposures in six CBCT units.

    PubMed

    Spin-Neto, R; Gotfredsen, E; Wenzel, A

    2014-01-01

    The aim of this study is to assess the variation in voxel value distribution in volumetric data sets obtained by six cone beam CT (CBCT) units, and the effect of time between exposures. Six CBCT units [Cranex(®) 3D (CRAN; Soredex Oy, Tuusula, Finland), Scanora(®) 3D (SCAN; Soredex Oy), NewTom™ 5G (NEWT; QR Srl, Verona, Italy), Promax(®) Dimax 3 (Planmeca Oy, Helsinki, Finland), i-CAT (Imaging Sciences International, Hatfield, PA) and 3D Accuitomo FPD80 (Morita, Kyoto, Japan)] were tested. Two volumetric data sets of a dry human skull embedded in acrylic were acquired by each CBCT unit in two sessions on separate days. Each session consisted of 20 exposures: 10 acquired with 30 min between exposures and 10 acquired immediately one after the other. CBCT data were exported as digital imaging and communications in medicine (DICOM) files and converted to text files. The text files were re-organized to contain x-, y- and z-position and grey shade for each voxel. The files were merged to contain 1 record per voxel position, including the voxel values from the 20 exposures in a session. For each voxel, subtractions were performed between Data Set 1 and the remaining 19 data sets (1 - 2, 1 - 3, etc) in a session. Means, medians, ranges and standard deviations for grey shade variation in the subtraction data sets were calculated for each unit and session. For all CBCT units, variation in voxel values was observed throughout the 20 exposures. A "fingerprint" for the grey shade variation was observed for CRAN, SCAN and NEWT. For the other units, the variation was (apparently) randomly distributed. Large discrepancies in voxel value distribution are seen in CBCT images. This variation should be considered in studies that assess minute changes in CBCT images.

  13. Critical role of sorafenib exposure over time for its antitumor activity in thyroid cancer.

    PubMed

    Bellesoeur, Audrey; Carton, Edith; Mir, Olivier; Groussin, Lionel; Blanchet, Benoit; Billemont, Bertrand; Clerc, Jérôme; Goldwasser, François

    2014-06-01

    Sorafenib, a multi-kinase inhibitor that targets the VEGF, PDGF and BRAF pathways, has demonstrated significant clinical activity in metastatic differentiated thyroid cancer. However, all patients eventually experience disease progression with a median progression-free survival close to 10 months. Since sorafenib exposure is known to decrease over time, we hypothesized that dose adjustments aiming to restore adequate exposure could lead to further clinical activity. We report, as a proof of concept on a patient with radio-iodine resistant metastatic thyroid cancer, who experienced disease progression after an initial response to sorafenib (400 mg twice daily). Whereas the thyroglobulin-progression-free survival at standard doses was 6 months, iterative dose optimization led to a prolonged progression-free survival up to 41 months. Sorafenib doses were increased up to 1600 mg bid, in order to maintain clinical activity, and to restore active plasma concentration, since sorafenib exposure had decreased over the time. Toxicity was mild and manageable for more than 2 years. However, the patient eventually experienced grade 3 proteinuria leading to treatment discontinuation. This observation opens up new horizons for daily management of radioactive iodine-refractory differentiated thyroid cancer patients progressing under standard doses of sorafenib, and stress the need to monitor its plasma concentration.

  14. Sequestering CO(2) by mineral carbonation: stability against acid rain exposure.

    PubMed

    Allen, Daniel J; Brent, Geoff F

    2010-04-01

    Mineral carbonation is a potentially attractive alternative to storage of compressed CO(2) in underground repositories, known as geosequestration. Processes for the conversion of basic ores, such as magnesium silicates, to carbonates have been proposed by various researchers, with storage of the carbonate as backfill in the original mine representing a solid carbon sink. The stability of such carbon sinks against acid rain and other sources of strong acids is examined here. It is acknowledged that in the presence of strong acid, carbonates will dissolve and release carbon dioxide. A sensitivity analysis covering annual average rainfall and pH that may be encountered in industrialized areas of the United States, China, Europe, and Australia was conducted to determine maximum CO(2) rerelease rates from mineral carbonation carbon sinks. This analysis is based on a worst-case premise that is equivalent to assuming infinitely rapid kinetics of dissolution of the carbonate. The analysis shows that under any likely conditions of pH and rainfall, leakage rates of stored CO(2) are negligible. This is illustrated in a hypothetical case study under Australian conditions. It is thus proposed that sequestration by mineral carbonation can be considered to be permanent on practical human time scales. Other possible sources of acid have also been considered.

  15. Sequestering CO(2) by mineral carbonation: stability against acid rain exposure.

    PubMed

    Allen, Daniel J; Brent, Geoff F

    2010-04-01

    Mineral carbonation is a potentially attractive alternative to storage of compressed CO(2) in underground repositories, known as geosequestration. Processes for the conversion of basic ores, such as magnesium silicates, to carbonates have been proposed by various researchers, with storage of the carbonate as backfill in the original mine representing a solid carbon sink. The stability of such carbon sinks against acid rain and other sources of strong acids is examined here. It is acknowledged that in the presence of strong acid, carbonates will dissolve and release carbon dioxide. A sensitivity analysis covering annual average rainfall and pH that may be encountered in industrialized areas of the United States, China, Europe, and Australia was conducted to determine maximum CO(2) rerelease rates from mineral carbonation carbon sinks. This analysis is based on a worst-case premise that is equivalent to assuming infinitely rapid kinetics of dissolution of the carbonate. The analysis shows that under any likely conditions of pH and rainfall, leakage rates of stored CO(2) are negligible. This is illustrated in a hypothetical case study under Australian conditions. It is thus proposed that sequestration by mineral carbonation can be considered to be permanent on practical human time scales. Other possible sources of acid have also been considered. PMID:20199068

  16. Personal exposure to ultrafine particles: Two-level statistical modeling of background exposure and time-activity patterns during three seasons.

    PubMed

    Deffner, Veronika; Küchenhoff, Helmut; Maier, Verena; Pitz, Mike; Cyrys, Josef; Breitner, Susanne; Schneider, Alexandra; Gu, Jianwei; Geruschkat, Uta; Peters, Annette

    2016-01-01

    Personal exposure to air pollution is associated with time- and location-specific factors including indoor and outdoor air pollution, meteorology and time activities. Our investigation aims at the description and identification of factors determining personal exposure to particle number concentration (PNC) in everyday situations. Ten volunteers recorded their personal exposure to PNC and kept an activity diary in three different seasons besides stationary measurements of ambient air pollution and meteorology. Background exposure to PNC was modelled using the most predictive variables. In a second step, the effects of the activities were calculated adjusted for the background exposure. The average personal PNC level was highest in winter and was three times higher than the mean stationary PNC level while staying indoors and two times higher while staying outdoors. Personal indoor PNC levels were significantly increased during the use of candles, cooking and the occurrence of smell of food. High stationary outdoor PNC levels and low dew point temperatures were associated with increased personal outdoor PNC levels. Times spent in public transport were associated with lower personal PNC levels than other times spent in transportation. Personal PNC levels in everyday situations exhibited a large variability because of seasonal, microenvironment-specific and activity-specific influences.

  17. Effect Modification of the Association of Cumulative Exposure and Cancer Risk by Intensity of Exposure and Time Since Exposure Cessation: A Flexible Method Applied to Cigarette Smoking and Lung Cancer in the SYNERGY Study

    PubMed Central

    Vlaanderen, Jelle; Portengen, Lützen; Schüz, Joachim; Olsson, Ann; Pesch, Beate; Kendzia, Benjamin; Stücker, Isabelle; Guida, Florence; Brüske, Irene; Wichmann, Heinz-Erich; Consonni, Dario; Landi, Maria Teresa; Caporaso, Neil; Siemiatycki, Jack; Merletti, Franco; Mirabelli, Dario; Richiardi, Lorenzo; Gustavsson, Per; Plato, Nils; Jöckel, Karl-Heinz; Ahrens, Wolfgang; Pohlabeln, Hermann; Tardón, Adonina; Zaridze, David; Field, John K.; 't Mannetje, Andrea; Pearce, Neil; McLaughlin, John; Demers, Paul; Szeszenia-Dabrowska, Neonila; Lissowska, Jolanta; Rudnai, Peter; Fabianova, Eleonora; Stanescu Dumitru, Rodica; Bencko, Vladimir; Foretova, Lenka; Janout, Vladimir; Boffetta, Paolo; Forastiere, Francesco; Bueno-de-Mesquita, Bas; Peters, Susan; Brüning, Thomas; Kromhout, Hans; Straif, Kurt; Vermeulen, Roel

    2014-01-01

    The indiscriminate use of the cumulative exposure metric (the product of intensity and duration of exposure) might bias reported associations between exposure to hazardous agents and cancer risk. To assess the independent effects of duration and intensity of exposure on cancer risk, we explored effect modification of the association of cumulative exposure and cancer risk by intensity of exposure. We applied a flexible excess odds ratio model that is linear in cumulative exposure but potentially nonlinear in intensity of exposure to 15 case-control studies of cigarette smoking and lung cancer (1985–2009). Our model accommodated modification of the excess odds ratio per pack-year of cigarette smoking by time since smoking cessation among former smokers. We observed negative effect modification of the association of pack-years of cigarette smoking and lung cancer by intensity of cigarette smoke for persons who smoked more than 20–30 cigarettes per day. Patterns of effect modification were similar across individual studies and across major lung cancer subtypes. We observed strong negative effect modification by time since smoking cessation. Application of our method in this example of cigarette smoking and lung cancer demonstrated that reducing a complex exposure history to a metric such as cumulative exposure is too restrictive. PMID:24355332

  18. Effect modification of the association of cumulative exposure and cancer risk by intensity of exposure and time since exposure cessation: a flexible method applied to cigarette smoking and lung cancer in the SYNERGY Study.

    PubMed

    Vlaanderen, Jelle; Portengen, Lützen; Schüz, Joachim; Olsson, Ann; Pesch, Beate; Kendzia, Benjamin; Stücker, Isabelle; Guida, Florence; Brüske, Irene; Wichmann, Heinz-Erich; Consonni, Dario; Landi, Maria Teresa; Caporaso, Neil; Siemiatycki, Jack; Merletti, Franco; Mirabelli, Dario; Richiardi, Lorenzo; Gustavsson, Per; Plato, Nils; Jöckel, Karl-Heinz; Ahrens, Wolfgang; Pohlabeln, Hermann; Tardón, Adonina; Zaridze, David; Field, John K; 't Mannetje, Andrea; Pearce, Neil; McLaughlin, John; Demers, Paul; Szeszenia-Dabrowska, Neonila; Lissowska, Jolanta; Rudnai, Peter; Fabianova, Eleonora; Stanescu Dumitru, Rodica; Bencko, Vladimir; Foretova, Lenka; Janout, Vladimir; Boffetta, Paolo; Forastiere, Francesco; Bueno-de-Mesquita, Bas; Peters, Susan; Brüning, Thomas; Kromhout, Hans; Straif, Kurt; Vermeulen, Roel

    2014-02-01

    The indiscriminate use of the cumulative exposure metric (the product of intensity and duration of exposure) might bias reported associations between exposure to hazardous agents and cancer risk. To assess the independent effects of duration and intensity of exposure on cancer risk, we explored effect modification of the association of cumulative exposure and cancer risk by intensity of exposure. We applied a flexible excess odds ratio model that is linear in cumulative exposure but potentially nonlinear in intensity of exposure to 15 case-control studies of cigarette smoking and lung cancer (1985-2009). Our model accommodated modification of the excess odds ratio per pack-year of cigarette smoking by time since smoking cessation among former smokers. We observed negative effect modification of the association of pack-years of cigarette smoking and lung cancer by intensity of cigarette smoke for persons who smoked more than 20-30 cigarettes per day. Patterns of effect modification were similar across individual studies and across major lung cancer subtypes. We observed strong negative effect modification by time since smoking cessation. Application of our method in this example of cigarette smoking and lung cancer demonstrated that reducing a complex exposure history to a metric such as cumulative exposure is too restrictive.

  19. In Vivo Human Time-Exposure Study of Orally Dosed Commercial Silver Nanoparticles

    PubMed Central

    Munger, Mark A.; Radwanski, Przemyslaw; Hadlock, Greg C.; Stoddard, Greg; Shaaban, Akram; Falconer, Jonathan; Grainger, David W.; Deering-Rice, Cassandra E.

    2013-01-01

    Background Human biodistribution, bioprocessing and possible toxicity of nanoscale silver receives increasing health assessment. Methods We prospectively studied commercial 10- and 32-ppm nanoscale silver particle solutions in a single-blind, controlled, cross-over, intent-to-treat, design. Healthy subjects (n=60) underwent metabolic, blood counts, urinalysis, sputum induction, and chest and abdomen magnetic resonance imaging. Silver serum and urine content was determined. Results No clinically important changes in metabolic, hematologic, or urinalysis measures were identified. No morphological changes were detected in the lungs, heart or abdominal organs. No significant changes were noted in pulmonary reactive oxygen species or pro-inflammatory cytokine generation. Conclusion In vivo oral exposure to these commercial nanoscale silver particle solutions does not prompt clinically important changes in human metabolic, hematologic, urine, physical findings or imaging morphology. Further study of increasing time exposure and dosing of silver nanoparticulate silver, and observation of additional organ systems is warranted to assert human toxicity thresholds. PMID:23811290

  20. Demonstration of real-time monitoring of a photolithographic exposure process using chemical ionization mass spectrometry

    SciTech Connect

    Mowry, C.D.

    1998-02-01

    Silicon wafers are coated with photoresist and exposed to ultraviolet (UV) light in a laboratory to simulate typical conditions expected in an actual semiconductor manufacturing process tool. Air is drawn through the exposure chamber and analyzed using chemical ionization mass spectrometry (CI/MS). Species that evaporate or outgas from the wafer are thus detected. The purpose of such analyses is to determine the potential of CI/MS as a real-time process monitoring tool. Results demonstrate that CI/MS can remotely detect the products evolved before, during, and after wafer UV exposure; and that the quantity and type of products vary with the photoresist coated on the wafer. Such monitoring could provide semiconductor manufacturers benefits in quality control and process analysis. Tool and photoresist manufacturers could also realize benefits from this measurement technique with respect to new tool, method, or photoresist development. The benefits realized can lead to improved device yields and reduced product and development costs.

  1. Influence of exposure time on the biotransformation rate of benzo(a)anthracene in fish

    SciTech Connect

    Maagd, P.G.J. de; Poorte, J. de; Sijm, D.T.H.M.; Opperhuizen, A.

    1995-12-31

    Biotransformation of PAH can yield in the formation of carcinogenic metabolites, therefore, determining the rate at which metabolites are formed is of importance to risk assessment. Biotransformation rates can be affected by inducing agents, hormonal status, temperature etc. To determine if biotransformation rates of PAH are influenced by auto-induction, juvenile fathead minnows were exposed to benzo(a)anthracene in water for various exposure times. After exposure for 5, 10, 24, 72, 168 or 336 hours no significant differences between biotransformation rates were found. The variation within each biotransformation rate was less than 20%. From these findings it is concluded that auto-induction by benzo(a)anthracene does not occur in fathead minnow.

  2. Timing of prenatal phthalate exposure in relation to genital endpoints in male newborns.

    PubMed

    Martino-Andrade, A J; Liu, F; Sathyanarayana, S; Barrett, E S; Redmon, J B; Nguyen, R H N; Levine, H; Swan, S H

    2016-07-01

    Prior studies report that penile size and male anogenital distance (AGD), sensitive markers of androgen action in utero, may be shortened by prenatal exposure to certain phthalates, including diethylhexyl phthalate (DEHP), but no human study has investigated the importance of exposure timing in these associations. The aim of this study was to examine the significance of exposure timing on the action of prenatal phthalates in particular DEHP, on male infant penile size and AGD. In The Infant Development and the Environment Study (TIDES) we measured penile width (PW) as well as anoscrotal distance (AGDAS ) and anopenile distance (AGPAP ) in newborn males. We modeled these endpoints in relation to phthalate metabolite concentrations in maternal urine samples collected in each trimester (T1, T2, and T3) in a subset of TIDES mothers (N = 168). PW was inversely associated with T2 oxidized DEHP metabolites, mono-2-ethyl-5-oxohexyl (MEOHP, β=-0.48; 95% confidence interval, -0.93, -0.02), MEHHP (-0.48; -0.92, -0.05), mono-2-ethyl-5-carboxypentyl (MECPP, -0.51; -1.01, -0.004), although no appreciable associations were seen between PW and T1 and T3 DEHP metabolite concentrations in this subset. Concentrations of DEHP metabolites in T1 urine samples were inversely related to male AGD. For example, in T1 samples in this subset of women mono-2-ethyl-5-hydroxyhexyl (MEHHP) was inversely associated with male AGDAP (β = -1.73; 95% confidence interval, -3.45, 0.0004). However, no appreciable associations were seen between AGD measures and any DEHP metabolite in T2 and T3 samples. These data suggest that DEHP exposure is inversely associated with AGD and PW, with PW primarily associated with T2 exposure and AGD associations seen only for T1 exposure, but no associations were found between T3 DEHP metabolites and any of these genital endpoints. These findings are consistent with data on critical windows in rodent studies, supporting the biological plausibility of these

  3. Dental erosion and sulfuric ion exposure levels in individuals working with sulfuric acid in lead storage battery manufacturing plant measured with mouth-rinse index.

    PubMed

    Suyama, Yuji; Takaku, Satoru; Okawa, Yoshikazu; Matsukubo, Takashi

    2010-01-01

    To investigate dental erosion in employees working with sulfuric acid at a lead storage battery manufacturing plant and level of personal exposure to sulfuric ions, we measured sulfuric ion concentrations in the mouth rinse of those employees. We also measured exposure levels from air samples obtained from 2 employees from the same plant who did not work with sulfuric acid using a portable air sampler. At the same time, we collected and compared their mouth rinses with those from other employees. More specifically, we measured and compared sulfuric ion, calcium, and magnesium concentrations, along with pH levels from the mouth rinse of these two groups. Positive correlations were found between sulfuric ion and calcium concentrations (r=0.61, p<0.005), calcium and magnesium concentrations (r=0.61, p<0.005), Ca/Mg and calcium concentrations (r=0.64, p<0.005), and sulfuric ion and magnesium concentrations (r=0.55, p<0.005). Negative correlations were found between sulfuric ion concentrations and pH levels (r=-0.31, p<0.01), and magnesium concentrations and pH levels (r=-0.32, p<0.01). This suggests that mouth rinse from employees working with sulfuric acid could function as an indicator of sulfuric ion concentration in the work environment. Furthermore, this could lead to the development of a more accurate indicator of individual exposure.

  4. Combined effects of exposure time and copper toxicity on the demography of Moina macrocopa (Crustacea: Cladocera).

    PubMed

    Gama-Flores, José Luis; Sarma, S S S; Nandini, S

    2009-01-01

    Cohort life table experiments were conducted on M. macrocopa using copper at three nominal concentrations (as CuSO(4), 0.1, 0.2 and 0.4 mg L(- 1), in addition to controls) for different periods of exposure (3 to 24 h). Age-specific survivorship of M. macrocopa decreased in relation to age of the cohort, concentration and duration of exposure to copper. Age-specific life expectancy curves also decreased with increasing age of the cohort. However, at low copper levels and shorter exposure time, there was an increase in life expectancy when the cohort was about 10 day old. Fecundity (m(x)) was nearly regular in controls; however, at higher copper levels and longer duration of exposure, the offspring production was more oscillating. The offspring production completely ceased when continuously exposed to CuSO(4) at 0.4 mg L(- 1). Most of the measured demography variables significantly decreased with increasing concentration of Cu in the medium. The average lifespan and life expectancy at birth varied 2.9 to 9.6 and 2.4 to 9.1 days, respectively. Gross reproductive rate (GRR) varied from 31 to 89 offspring female(- 1) lifespan(- 1), while the survival-weighted net reproductive rates were nearly one-third of the GRR. Generation time of M. macrocopa varied from 5 to 7 days while the rate of population increase ranged from 0.36 to 0.84 per day. The results are discussed in relation to the sensitivity of M. macrocopa to copper toxicity and the necessity of amending the national water quality criteria in Mexico. PMID:19089719

  5. Real-Time Aircraft Cosmic Ray Radiation Exposure Predictions from the NAIRAS Model

    NASA Astrophysics Data System (ADS)

    Mertens, C. J.; Tobiska, W.; Kress, B. T.; Xu, X.

    2012-12-01

    The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) is a prototype operational model for predicting commercial aircraft radiation exposure from galactic and solar cosmic rays. NAIRAS predictions are currently streaming live from the project's public website, and the exposure rate nowcast is also available on the SpaceWx smartphone app for iPhone, IPad, and Android. Cosmic rays are the primary source of human exposure to high linear energy transfer radiation at aircraft altitudes, which increases the risk of cancer and other adverse health effects. Thus, the NAIRAS model addresses an important national need with broad societal, public health and economic benefits. There is also interest in extending NAIRAS to the LEO environment to address radiation hazard issues for the emerging commercial spaceflight industry. The processes responsible for the variability in the solar wind, interplanetary magnetic field, solar energetic particle spectrum, and the dynamical response of the magnetosphere to these space environment inputs, strongly influence the composition and energy distribution of the atmospheric ionizing radiation field. Real-time observations are required at a variety of locations within the geospace environment. The NAIRAS model is driven by real-time input data from ground-, atmospheric-, and space-based platforms. During the development of the NAIRAS model, new science questions and observational data gaps were identified that must be addressed in order to obtain a more reliable and robust operational model of atmospheric radiation exposure. The focus of this talk is to present the current capabilities of the NAIRAS model, discuss future developments in aviation radiation modeling and instrumentation, and propose strategies and methodologies of bridging known gaps in current modeling and observational capabilities.

  6. Wearable real-time direct reading naphthalene and VOC personal exposure monitor

    NASA Astrophysics Data System (ADS)

    Hug, W. F.; Bhartia, R.; Reid, R. D.; Reid, M. R.; Oswal, P.; Lane, A. L.; Sijapati, K.; Sullivan, K.; Hulla, J. E.; Snawder, J.; Proctor, S. P.

    2012-06-01

    Naphthalene has been identified by the National Research Council as a serious health hazard for personnel working with jet fuels and oil-based sealants containing naphthalene. We are developing a family of miniature, self-contained, direct reading personal exposure monitors (PEMs) to detect, differentiate, quantify, and log naphthalene and other volatile organic compounds (VOCs) in the breathing zone of the wearer or in the hands of an industrial hygienist with limits of detection in the low parts per billion (ppb) range. The VOC Dosimeter (VOCDos) described here is a PEM that provides real-time detection and data logging of exposure as well as accumulated dose, with alarms addressing long term and immediate exposure limits. We will describe the sensor, which employs optical methods with a unique excitation source and rapidly refreshable vapor concentrator. This paper addresses the rapidly increasing awareness of the health risks of inhaling jet fuel vapors by Department of Defense (DOD) personnel engaged in or around jet fueling operations. Naphthalene is a one to three percent component of the 5 billion gallons of jet fuels used annually by DOD. Naphthalene is also a component of many other petroleum products such as asphalt and other oil-based sealants. The DOD is the single largest user of petroleum fuels in the United States (20% of all petroleum fuel used). The VOCDos wearable sensor provides real-time detection and data logging of exposure as well as accumulated dose. We will describe the sensor, which employs endogenous fluorescence from VOCs accumulated on a unique, rapidly refreshable, patent-pending concentrator, excited by a unique deep ultraviolet excitation source.

  7. Tumors and Proliferative Lesions in Adult Offspring After Maternal Exposure to Methylarsonous Acid During Gestation in CD1 Mice

    EPA Science Inventory

    Developmental exposure to inorganic arsenic is carcinogenic in humans and mice, and adult offspring of mice exposed to inorganic arsenic can develop tumors of the lung, liver, adrenal, uterus, and ovary. It has been suggested that methylarsonous acid (MMA3+), a product of the bi...

  8. Impact of boric acid exposure at different concentrations on testicular DNA and male rats fertility.

    PubMed

    El-Dakdoky, Mai H; Abd El-Wahab, Hanan M F

    2013-06-01

    The aim of this study was to investigate the consequences of exposure to three levels of boric acid (BA) on male rats reproduction, fertility and progeny outcome, with emphasis on testicular DNA level and quality. Adult male rats (12 weeks old) were treated orally with 125, 250 and 500 mg/kg bwt/d of BA for 60 d. The results indicated that BA administration at 125 mg/kg bwt had no adverse effects on fertility, sperm characteristics or prenatal development of the impregnated females. However, at dose 250 mg, BA treatment significantly increased serum nitric oxide, testosterone, estradiol levels and testicular boron and calcium levels and also significantly reduced serum arginase activity, sperm quality and testicular DNA content with minor DNA fragmentation. The impact of BA exposure at dose 250 mg on male rats fertility was translated into increases in pre-implantation loss with a resulting decrease in the number of live fetuses/litter. In addition to the significant alteration of biochemical measurements, observed at dose 250 mg, administration of BA at 500 mg caused testicular atrophy, severe damage of spermatogenesis, spermiation failure and significant reduction of Mg and Zn testicular levels. None of the male rats, treated with 500 mg/kg bwt, could impregnate untreated females, suggesting the occurrence of definitive loss of fertility. In conclusion, BA impaired fertility, in a dose-dependant manner, by targeting the highly proliferative cells, the germ cells, through decreasing DNA synthetic rate rather than the induction of DNA damage. PMID:23301826

  9. Impact of boric acid exposure at different concentrations on testicular DNA and male rats fertility.

    PubMed

    El-Dakdoky, Mai H; Abd El-Wahab, Hanan M F

    2013-06-01

    The aim of this study was to investigate the consequences of exposure to three levels of boric acid (BA) on male rats reproduction, fertility and progeny outcome, with emphasis on testicular DNA level and quality. Adult male rats (12 weeks old) were treated orally with 125, 250 and 500 mg/kg bwt/d of BA for 60 d. The results indicated that BA administration at 125 mg/kg bwt had no adverse effects on fertility, sperm characteristics or prenatal development of the impregnated females. However, at dose 250 mg, BA treatment significantly increased serum nitric oxide, testosterone, estradiol levels and testicular boron and calcium levels and also significantly reduced serum arginase activity, sperm quality and testicular DNA content with minor DNA fragmentation. The impact of BA exposure at dose 250 mg on male rats fertility was translated into increases in pre-implantation loss with a resulting decrease in the number of live fetuses/litter. In addition to the significant alteration of biochemical measurements, observed at dose 250 mg, administration of BA at 500 mg caused testicular atrophy, severe damage of spermatogenesis, spermiation failure and significant reduction of Mg and Zn testicular levels. None of the male rats, treated with 500 mg/kg bwt, could impregnate untreated females, suggesting the occurrence of definitive loss of fertility. In conclusion, BA impaired fertility, in a dose-dependant manner, by targeting the highly proliferative cells, the germ cells, through decreasing DNA synthetic rate rather than the induction of DNA damage.

  10. Trichloroacetic acid cycling in Sitka spruce saplings and effects on sapling health following long term exposure.

    PubMed

    Dickey, C A; Heal, K V; Stidson, R T; Koren, R; Schröder, P; Cape, J N; Heal, M R

    2004-07-01

    Trichloroacetic acid (TCA, CCl(3)COOH) has been associated with forest damage but the source of TCA to trees is poorly characterised. To investigate the routes and effects of TCA uptake in conifers, 120 Sitka spruce (Picea sitchensis (Bong.) Carr) saplings were exposed to control, 10 or 100 microg l(-1) solutions of TCA applied twice weekly to foliage only or soil only over two consecutive 5-month growing seasons. At the end of each growing season similar elevated TCA concentrations (approximate range 200-300 ng g(-1) dwt) were detected in both foliage and soil-dosed saplings exposed to 100 microg l(-1) TCA solutions showing that TCA uptake can occur from both exposure routes. Higher TCA concentrations in branchwood of foliage-dosed saplings suggest that atmospheric TCA in solution is taken up indirectly into conifer needles via branch and stemwood. TCA concentrations in needles declined slowly by only 25-30% over 6 months of winter without dosing. No effect of TCA exposure on sapling growth was measured during the experiment. However at the end of the first growing season needles of saplings exposed to 10 or 100 microg l(-1) foliage-applied TCA showed significantly more visible damage, higher activities of some detoxifying enzymes, lower protein contents and poorer water control than needles of saplings dosed with the same TCA concentrations to the soil. At the end of each growing season the combined TCA storage in needles, stemwood, branchwood and soil of each sapling was <6% of TCA applied. Even with an estimated half-life of tens of days for within-sapling elimination of TCA during the growing season, this indicates that TCA is eliminated rapidly before uptake or accumulates in another compartment. Although TCA stored in sapling needles accounted for only a small proportion of TCA stored in the sapling/soil system it appears to significantly affect some measures of sapling health.

  11. Effects of acid aerosol exposure on the surface properties of airway mucus

    SciTech Connect

    Lee, M.M.; Schuerch, S.; Roth, S.H.

    1995-12-31

    It was hypothesized that the mucous layer lining the tracheas of rats and guinea pigs contains surfactant material capable of lowering the air/mucus surface tension, {gamma}, and that exposure to an irritant aerosol would raise the {gamma}. The {gamma} of the surface film was measured directly by a spreading droplet technique and indirectly by displacement of polymethyl methacrylate particles into the aqueous layer. The morphology of the mucous film was examined by electron microscopy after nonaqueous fixation. {gamma} was 33.3 {plus_minus} 0.70 (SE) mN/m and 32.3 {plus_minus} 0.68 (SE) mN/m for the normal rat and guinea pig trachea, respectively. Exposure for 4 h to aerosols of sulfuric acid (94.1 {plus_minus} 18.68 (SD) and 43.3 {plus_minus} 4.57 (SD) mg/m{sup 3}) caused a several-fold increase in thickness of the mucous layer with exudation of protein-like material. The osmiophilic surfactant film at the air/mucus interface became irregularly thickened and multilayered. Despite these morphological changes {gamma} remained low, 33.2 {plus_minus} 0.43 (SE) mN/m and 32.6 {plus_minus} 0.60 (SE) mN/m for rats and guinea pigs, respectively, and displacement of particles into the subphase was not compromised. The results indicate that rodent tracheas are able to maintain a low surface tension in the presence of injury. 24 refs., 9 figs.

  12. Acute exposure to 2G phase shifts the rat circadian timing system

    NASA Technical Reports Server (NTRS)

    Hoban-Higgins, T. M.; Murakami, D. M.; Tandon, T.; Fuller, C. A.

    1995-01-01

    The circadian timing system (CTS) provides internal and external temporal coordination of an animal's physiology and behavior. In mammals, the generation and coordination of these circadian rhythms is controlled by a neural pacemaker, the suprachiasmatic nucleus (SCN), located within the hypothalamus. The pacemaker is synchronized to the 24 hour day by time cures (zeitgebers) such as the light/dark cycle. When an animal is exposed to an environment without time cues, the circadian rhythms maintain internal temporal coordination, but exhibit a 'free-running' condition in which the period length is determined by the internal pacemaker. Maintenance of internal and external temporal coordination are critical for normal physiological and psychological function in human and non-human primates. Exposure to altered gravitational environments has been shown to affect the amplitude, mean, and timing of circadian rhythms in species ranging from unicellular organisms to man. However, it has not been determined whether altered gravitational fields have a direct effect on the neural pacemaker, or affect peripheral parameters. In previous studies, the ability of a stimulus to phase shift circadian rhythms was used to determine whether a stimulus has a direct effect on the neural pacemaker. The present experiment was performed in order to determine whether acute exposure to a hyperdynamic field could phase shift circadian rhythms.

  13. Controlling surface roughness in vapor-deposited poly(amic acid) films by solvent-vapor exposure.

    PubMed

    Anthamatten, Mitchell; Letts, Stephan A; Cook, Robert C

    2004-07-20

    A series of vapor-deposited poly(amic acid) (PAA) films were exposed to dimethyl sulfoxide (DMSO) vapors to investigate sorption kinetics and surface smoothing phenomena. Gravimetric sorption and secondary-ion mass spectrometry (SIMS) results are both consistent with frontal (case II) diffusion. These experiments suggest that the solvent front is defined by a sharp interface that delineates the swollen material from the unswollen material. Solvent-vapor smoothing was studied by first depositing PAA onto rough aluminum surfaces, and then, during solvent-vapor exposure, the surface topology was continuously monitored using a light interference microscope. The resulting time-dependent power spectra indicate that high-frequency defects smooth faster than low-frequency defects. This frequency dependence was further investigated by depositing PAA onto a series of sinusoidal surfaces and exposing them to solvent vapor inside a flow channel. The sinusoidal amplitudes decay exponentially with time, with decay constants that are proportional to the surface frequency. To explain the physics of surface smoothing, a two-parameter model is presented and agrees qualitatively with experimental data.

  14. Folic acid and its photoproducts, 6-formylpterin and pterin-6-carboxylic acid, as generators of reactive oxygen species in skin cells during UVA exposure.

    PubMed

    Juzeniene, Asta; Grigalavicius, Mantas; Ma, Li Wei; Juraleviciute, Marina

    2016-02-01

    Folic acid (FA) is the synthetic form of folate (vitamin B9), present in supplements and fortified foods. During ultraviolet (UV) radiation FA is degraded to 6-formylpterin (FPT) and pterin-6-carboxylic acid (PCA) which generate reactive oxygen species (ROS) and may be phototoxic. The aim of the present study was to investigate the production of ROS and phototoxicity of FA, FPT and PCA in skin cells during UVA exposure. The production of ROS and phototoxicity of FA, FPT and PCA were studied in the immortal human keratinocytes (HaCaT) and malignant skin cells (A431 and WM115) during UVA exposure. Increased ROS production and the photoinactivation of cells in vitro were observed during UVA exposure in the presence of FA, FPT and PCA. HPLC analysis revealed that 10 μM FA photodegradation was around 2.1 and 5.8-fold faster than that of 5 μM and 1 μM FA. Photodegradation of FA is concentration dependent, and even non-phototoxic doses of FA and its photoproducts, FPT and PCA, generate high levels of ROS in vitro. FA, FPT and PCA are phototoxic in vitro. The photodegradation of topical or unmetabolized FA during UV exposure via sunlight, sunbeds or phototherapy may lead to ROS production, to the cutaneous folate deficiency, skin photocarcinogenesis and other deleterious skin effects. Further studies are needed to confirm whether UV exposure can decrease cutaneous and serum folate levels in humans taking FA supplements or using cosmetic creams with FA.

  15. Simvastatin Hydroxy Acid Fails to Attain Sufficient Central Nervous System Tumor Exposure to Achieve a Cytotoxic Effect: Results of a Preclinical Cerebral Microdialysis Study.

    PubMed

    Patel, Yogesh T; Jacus, Megan O; Davis, Abigail D; Boulos, Nidal; Turner, David C; Vuppala, Pradeep K; Freeman, Burgess B; Gilbertson, Richard J; Stewart, Clinton F

    2016-04-01

    3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors were potent hits against a mouse ependymoma cell line, but their effectiveness against central nervous system tumors will depend on their ability to cross the blood-brain barrier and attain a sufficient exposure at the tumor. Among 3-hydroxy-3-methylglutaryl coenzyme A inhibitors that had activity in vitro, we prioritized simvastatin (SV) as the lead compound for preclinical pharmacokinetic studies based on its potential for central nervous system penetration as determined from in silico models. Furthermore, we performed systemic plasma disposition and cerebral microdialysis studies of SV (100 mg/kg, p.o.) in a murine model of ependymoma to characterize plasma and tumor extracellular fluid (tECF) pharmacokinetic properties. The murine dosage of SV (100 mg/kg, p.o.) was equivalent to the maximum tolerated dose in patients (7.5 mg/kg, p.o.) based on equivalent plasma exposure of simvastatin acid (SVA) between the two species. SV is rapidly metabolized in murine plasma with 15 times lower exposure compared with human plasma. SVA exposure in tECF was <33.8 ± 11.9 µg/l per hour, whereas the tumor to plasma partition coefficient of SVA was <0.084 ± 0.008. Compared with in vitro washout IC50 values, we did not achieve sufficient exposure of SVA in tECF to suggest tumor growth inhibition; therefore, SV was not carried forward in subsequent preclinical efficacy studies. PMID:26802130

  16. Radiation Exposure and Health Effects - is it Time to Reassess the Real Consequences?

    PubMed

    Thomas, G A; Symonds, P

    2016-04-01

    Our acceptance of exposure to radiation is somewhat schizophrenic. We accept that the use of high doses of radiation is still one of the most valuable weapons in our fight against cancer, and believe that bathing in radioactive spas is beneficial. On the other hand, as a species, we are fearful of exposure to man-made radiation as a result of accidents related to power generation, even though we understand that the doses are orders of magnitude lower than those we use everyday in medicine. The 70th anniversary of the detonation of the atomic bombs in Hiroshima and Nagasaki was marked in 2015. The 30th anniversary of the Chernobyl nuclear power plant accident will be marked in April 2016. March 2016 also sees the fifth anniversary of the accident at the Fukushima nuclear power plant. Perhaps now is an opportune time to assess whether we are right to be fearful of the effects of low doses of radiation, or whether actions taken because of our fear of radiation actually cause a greater detriment to health than the direct effect of radiation exposure.

  17. Radiation Exposure and Health Effects - is it Time to Reassess the Real Consequences?

    PubMed

    Thomas, G A; Symonds, P

    2016-04-01

    Our acceptance of exposure to radiation is somewhat schizophrenic. We accept that the use of high doses of radiation is still one of the most valuable weapons in our fight against cancer, and believe that bathing in radioactive spas is beneficial. On the other hand, as a species, we are fearful of exposure to man-made radiation as a result of accidents related to power generation, even though we understand that the doses are orders of magnitude lower than those we use everyday in medicine. The 70th anniversary of the detonation of the atomic bombs in Hiroshima and Nagasaki was marked in 2015. The 30th anniversary of the Chernobyl nuclear power plant accident will be marked in April 2016. March 2016 also sees the fifth anniversary of the accident at the Fukushima nuclear power plant. Perhaps now is an opportune time to assess whether we are right to be fearful of the effects of low doses of radiation, or whether actions taken because of our fear of radiation actually cause a greater detriment to health than the direct effect of radiation exposure. PMID:26880062

  18. Neurodevelopmental alcohol exposure elicits long-term changes to gene expression that alter distinct molecular pathways dependent on timing of exposure

    PubMed Central

    2013-01-01

    Background Maternal alcohol consumption is known to adversely affect fetal neurodevelopment. While it is known that alcohol dose and timing play a role in the cognitive and behavioral changes associated with prenatal alcohol exposure, it is unclear what developmental processes are disrupted that may lead to these phenotypes. Methods Mice (n=6 per treatment per developmental time) were exposed to two acute doses of alcohol (5 g/kg) at neurodevelopmental times representing the human first, second, or third trimester equivalent. Mice were reared to adulthood and changes to their adult brain transcriptome were assessed using expression arrays. These were then categorized based on Gene Ontology annotations, canonical pathway associations, and relationships to interacting molecules. Results The results suggest that ethanol disrupts biological processes that are actively occurring at the time of exposure. These include cell proliferation during trimester one, cell migration and differentiation during trimester two, and cellular communication and neurotransmission during trimester three. Further, although ethanol altered a distinct set of genes depending on developmental timing, many of these show interrelatedness and can be associated with one another via ‘hub’ molecules and pathways such as those related to huntingtin and brain-derived neurotrophic factor. Conclusions These changes to brain gene expression represent a ‘molecular footprint’ of neurodevelopmental alcohol exposure that is long-lasting and correlates with active processes disrupted at the time of exposure. This study provides further support that there is no neurodevelopmental time when alcohol cannot adversely affect the developing brain. PMID:23497526

  19. Developmental Subchronic Exposure to Diphenylarsinic Acid Induced Increased Exploratory Behavior, Impaired Learning Behavior, and Decreased Cerebellar Glutathione Concentration in Rats

    PubMed Central

    Negishi, Takayuki; Matsunaga, Yuki

    2013-01-01

    In Japan, people using water from the well contaminated with high-level arsenic developed neurological, mostly cerebellar, symptoms, where diphenylarsinic acid (DPAA) was a major compound. Here, we investigated the adverse effects of developmental exposure to 20mg/l DPAA in drinking water (early period [0–6 weeks of age] and/or late period [7–12]) on behavior and cerebellar development in male rats. In the open field test at 6 weeks of age, early exposure to DPAA significantly increased exploratory behaviors. At 12 weeks of age, late exposure to DPAA similarly increased exploratory behavior independent of the early exposure although a 6-week recovery from DPAA could reverse that change. In the passive avoidance test at 6 weeks of age, early exposure to DPAA significantly decreased the avoidance performance. Even at 12 weeks of age, early exposure to DPAA significantly decreased the test performance, which was independent of the late exposure to DPAA. These results suggest that the DPAA-induced increase in exploratory behavior is transient, whereas the DPAA-induced impairment of passive avoidance is long lasting. At 6 weeks of age, early exposure to DPAA significantly reduced the concentration of cerebellar total glutathione. At 12 weeks of age, late, but not early, exposure to DPAA also significantly reduced the concentration of cerebellar glutathione, which might be a primary cause of oxidative stress. Early exposure to DPAA induced late-onset suppressed expression of NMDAR1 and PSD95 protein at 12 weeks of age, indicating impaired glutamatergic system in the cerebellum of rats developmentally exposed to DPAA. PMID:24008832

  20. Space Weathering Effects in Lunar Soils: The Roles of Surface Exposure Time and Bulk Chemical Composition

    NASA Technical Reports Server (NTRS)

    Zhang, Shouliang; Keller, Lindsay P.

    2011-01-01

    Space weathering effects on lunar soil grains result from both radiation-damaged and deposited layers on grain surfaces. Typically, solar wind irradiation forms an amorphous layer on regolith silicate grains, and induces the formation of surficial metallic Fe in Fe-bearing minerals [1,2]. Impacts into the lunar regolith generate high temperature melts and vapor. The vapor component is largely deposited on the surfaces of lunar soil grains [3] as is a fraction of the melt [4, this work]. Both the vapor-deposits and the deposited melt typically contain nanophase Fe metal particles (npFe0) as abundant inclusions. The development of these rims and the abundance of the npFe0 in lunar regolith, and thus the optical properties, vary with the soil mineralogy and the length of time the soil grains have been exposed to space weathering effects [5]. In this study, we used the density of solar flare particle tracks in soil grains to estimate exposure times for individual grains and then perform nanometer-scale characterization of the rims using transmission electron microscopy (TEM). The work involved study of lunar soil samples with different mineralogy (mare vs. highland) and different exposure times (mature vs. immature).

  1. Self-reported exertion levels on time/activity diaries: application to exposure assessment

    SciTech Connect

    Schwab, M.; Terblanche, A.P.; Spengler, J.D. )

    1991-07-01

    Recent developments in air pollution analysis have focused on methods for collecting data on contaminant levels in the locations actually frequented by people, especially personal monitoring. While there is still much to understand about human exposures, the next advancements will be in the area of dose assessment. This paper discusses the results of a study designed to provide data for linking exposure to dose. Specifically, we used time/activity diaries to collect information on the exertion levels associated with the reported activities. As part of a community health study, 91 children between the ages of 9 and 11 kept diaries over a two-week summer-time period (July 1989) and during a two-week school-time period (September 1989). The diary was also administered for two days to 42 teenagers between the ages of 15 and 17. This paper describes our concerns about interpreting self-reported exertion levels, particularly with respect to the disparity between participant and researcher perception and coding. We then present the distribution of exertion levels associated with children's activities, highlighting seasonal, day-of-week, and age-group differences.

  2. Non parametric denoising methods based on wavelets: Application to electron microscopy images in low exposure time

    SciTech Connect

    Soumia, Sid Ahmed; Messali, Zoubeida; Ouahabi, Abdeldjalil; Trepout, Sylvain E-mail: cedric.messaoudi@curie.fr Messaoudi, Cedric E-mail: cedric.messaoudi@curie.fr Marco, Sergio E-mail: cedric.messaoudi@curie.fr

    2015-01-13

    The 3D reconstruction of the Cryo-Transmission Electron Microscopy (Cryo-TEM) and Energy Filtering TEM images (EFTEM) hampered by the noisy nature of these images, so that their alignment becomes so difficult. This noise refers to the collision between the frozen hydrated biological samples and the electrons beam, where the specimen is exposed to the radiation with a high exposure time. This sensitivity to the electrons beam led specialists to obtain the specimen projection images at very low exposure time, which resulting the emergence of a new problem, an extremely low signal-to-noise ratio (SNR). This paper investigates the problem of TEM images denoising when they are acquired at very low exposure time. So, our main objective is to enhance the quality of TEM images to improve the alignment process which will in turn improve the three dimensional tomography reconstructions. We have done multiple tests on special TEM images acquired at different exposure time 0.5s, 0.2s, 0.1s and 1s (i.e. with different values of SNR)) and equipped by Golding beads for helping us in the assessment step. We herein, propose a structure to combine multiple noisy copies of the TEM images. The structure is based on four different denoising methods, to combine the multiple noisy TEM images copies. Namely, the four different methods are Soft, the Hard as Wavelet-Thresholding methods, Bilateral Filter as a non-linear technique able to maintain the edges neatly, and the Bayesian approach in the wavelet domain, in which context modeling is used to estimate the parameter for each coefficient. To ensure getting a high signal-to-noise ratio, we have guaranteed that we are using the appropriate wavelet family at the appropriate level. So we have chosen âĂIJsym8âĂİ wavelet at level 3 as the most appropriate parameter. Whereas, for the bilateral filtering many tests are done in order to determine the proper filter parameters represented by the size of the filter, the range parameter and the

  3. Sociality and Sickness: Have Cytokines Evolved to Serve Social Functions beyond Times of Pathogen Exposure?

    PubMed Central

    Hennessy, Michael B.; Deak, Terrence; Schiml, Patricia A.

    2013-01-01

    During pathogen exposure or some forms of stress, proinflammatory processes induce an array of motivated and behavioral adjustments termed “sickness behaviors”. Although withdrawal from social interactions is a commonly observed sickness behavior, the relation between social behavior and sickness is much more complex. Sickness can suppress or stimulate social behavior. Sickness can serve as a social cue. Stressors that are social in nature can induce sickness behaviors, and sickness behavior can be readily suppressed by meaningful social stimuli. The nature, context, and timing of these effects together suggest that cytokine-induced behavior may play a role in mediating social interactions in various non-pathological conditions. PMID:24184399

  4. Human Exposure and Elimination Kinetics of Chlorinated Polyfluoroalkyl Ether Sulfonic Acids (Cl-PFESAs).

    PubMed

    Shi, Yali; Vestergren, Robin; Xu, Lin; Zhou, Zhen; Li, Chuangxiu; Liang, Yong; Cai, Yaqi

    2016-03-01

    The incomplete mass-balance of organic fluorine in human serum indicates the existence of unknown per- and polyfluoroalkyl substances (PFASs) with persistent and bioaccumulative properties. Here we characterized human exposure and elimination kinetics of chlorinated polyfluoroalkyl ether sulfonic acids (Cl-PFESAs) in metal plating workers (n = 19), high fish consumers (n = 45), and background controls (n = 8). Cl-PFESAs were detected in >98% of the sampled individuals with serum concentrations ranging <0.019-5040 ng/mL. Statistically higher median serum levels were observed in high fish consumers (93.7 ng/mL) and metal plating workers (51.5 ng/mL) compared to the background control group (4.78 ng/mL) (Kruskal-Wallis rank sum test, p < 0.01). Cl-PFESAs could account for 0.269 to 93.3% of ∑PFASs in human serum indicating that this compound class may explain a substantial fraction of previously unidentified organic fluorine in the Chinese population. Estimated half-lives for renal clearance (median 280 years; range 7.1-4230 years) and total elimination (median 15.3 years; range 10.1-56.4 years) for the eight carbon Cl-PFESA suggest that this is the most biopersistent PFAS in humans reported to date. The apparent ubiquitous distribution and slow elimination kinetics in humans underscore the need for more research and regulatory actions on Cl-PFESAs and PFAS alternatives with similar chemical structures.

  5. Prenatal domoic acid exposure disrupts mouse pro-social behavior and functional connectivity MRI.

    PubMed

    Mills, Brian D; Pearce, Hadley L; Khan, Omar; Jarrett, Ben R; Fair, Damien A; Lahvis, Garet P

    2016-07-15

    Domoic acid (DA) is a toxin produced by marine algae and known primarily for its role in isolated outbreaks of Amnestic Shellfish Poisoning and for the damage it inflicts on marine mammals, particularly California sea lions. Lethal effects of DA are often preceded by seizures and coma. Exposure to DA during development can result in subtle and highly persistent effects on brain development and include behavioral changes that resemble diagnostic features of schizophrenia and anomalies in social behavior we believe are relevant to autism spectrum disorder (ASD). To more fully examine this hypothesis, we chose to examine adolescent mice exposed in utero to DA for endpoints relevant to ASD, specifically changes in social behavior and network structure, the latter measured by resting state functional connectivity (rs-fcMRI). We found that male offspring exposed in utero to DA expressed reproducible declines in social interaction and atypical patterns of functional connectivity in the anterior cingulate, a region of the default mode network that is critical for social functioning. We also found disruptions in global topology in regions involved in the processing of reward, social, and sensory experiences. Finally, we found that DA exposed males expressed a pattern of local over-connectivity. These anomalies in brain connectivity bear resemblance to connectivity patterns in ASD and help validate DA-exposed mice as a model of this mental disability.

  6. Prenatal domoic acid exposure disrupts mouse pro-social behavior and functional connectivity MRI.

    PubMed

    Mills, Brian D; Pearce, Hadley L; Khan, Omar; Jarrett, Ben R; Fair, Damien A; Lahvis, Garet P

    2016-07-15

    Domoic acid (DA) is a toxin produced by marine algae and known primarily for its role in isolated outbreaks of Amnestic Shellfish Poisoning and for the damage it inflicts on marine mammals, particularly California sea lions. Lethal effects of DA are often preceded by seizures and coma. Exposure to DA during development can result in subtle and highly persistent effects on brain development and include behavioral changes that resemble diagnostic features of schizophrenia and anomalies in social behavior we believe are relevant to autism spectrum disorder (ASD). To more fully examine this hypothesis, we chose to examine adolescent mice exposed in utero to DA for endpoints relevant to ASD, specifically changes in social behavior and network structure, the latter measured by resting state functional connectivity (rs-fcMRI). We found that male offspring exposed in utero to DA expressed reproducible declines in social interaction and atypical patterns of functional connectivity in the anterior cingulate, a region of the default mode network that is critical for social functioning. We also found disruptions in global topology in regions involved in the processing of reward, social, and sensory experiences. Finally, we found that DA exposed males expressed a pattern of local over-connectivity. These anomalies in brain connectivity bear resemblance to connectivity patterns in ASD and help validate DA-exposed mice as a model of this mental disability. PMID:27050322

  7. Prenatal ethanol exposure reduces the effects of excitatory amino acids in the rat hippocampus

    SciTech Connect

    Noble, E.P.; Ritchie, T. )

    1989-01-01

    Chronic alcohol ingestion during pregnancy can lead to the Fetal Alcohol Syndrome (FAS), a disorder marked by learning disabilities. A rat model of FAS was used by introducing pregnant Sprague-Dawley rats to a liquid diet containing 35% ethanol-derived calories (E), while a second group was pair-fed an isocaloric liquid diet without ethanol (P). A third group of pregnant dams received ad libitum lab chow (C). At parturition, pups from the E and P groups were cross fostered by C mothers and all groups received lab chow. During adulthood, male offspring were sacrificed and hippocampal and prefrontal cortical slices were prelabeled with (3H)inositol. Phosphoinositide (PI) hydrolysis was determined by measuring the accumulation of (3H)inositol phosphates in the presence of LiCl in response to activation of various excitatory amino acid (EAA) receptors. In hippocampal slices, ibotenate- and quisqualate-induced PI hydrolysis was reduced in E compared to P and C animals. Moreover, the inhibitory effect of N-methyl-D-aspartate (NMDA) on carbachol-induced PI hydrolysis, evident in P and C animals, was completely abolished in the hippocampus of E animals. In contrast, in the prefrontal cerebral cortex, this inhibitory effect of NMDA prevailed even in the E animals. The evidence suggests that prenatal ethanol exposure alters the activity of EAA receptors in the hippocampal generation of 2nd messengers.

  8. Acid sulphate soil disturbance and metals in groundwater: implications for human exposure through home grown produce.

    PubMed

    Hinwood, Andrea Lee; Horwitz, Pierre; Appleyard, Steve; Barton, Caroline; Wajrak, Magda

    2006-09-01

    A significant emerging environmental problem is the disturbance and oxidation of soils with high levels of iron sulphide minerals resulting in acidification and causing the mobilization of metals into groundwater. This process is occurring in many parts of the world. In Western Australia, impacted groundwater is extracted by residents for domestic use. We sought to establish domestic use patterns of bore water and the concentration of metals. Sixty-seven domestic bore water samples clearly indicated oxidation of sulphidic materials with heavy metal concentrations ranging for aluminium (exposure to heavy metals via the consumption of home grown produce. This warrants further investigation in light of increasing acid sulphate soil disturbance in many locations.

  9. Loblolly pine and slash pine responses to acute aluminum and acid exposures.

    PubMed

    Nowak, Jaroslaw; Friend, Alexander L

    2006-09-01

    In response to concerns about aluminum and HCl exposure associated with rocket motor testing and launches, survival and growth of full-sib families of loblolly pine (Pinus taeda L.) and slash pine (Pinus elliottii Engelm.) were evaluated in a nursery bed experiment. Each species was exposed to a single soil application of aluminum chloride (0.33 M AlCl(3), pH 2.5), hydrochloric acid (0.39 M HCl, pH 0.6) or water, with or without mycorrhizal inoculation with Pisolithus tinctorius (Coker and Couch). After 20 weeks without inoculation, survival in AlCl(3) and HCl treatments averaged 52% for loblolly pine and 72% for slash pine. Inoculation improved survival of loblolly pine, receiving HCl from 49 to 73%, and of those receiving AlCl3, from 55 to 90%. Inoculation also resulted in improved survival and growth of individual families in AlCl(3), but not in HCl treatments. Results illustrate the relative resistance of both pine species to the acute treatments supplied, the improvement in resistance associated with mycorrhizal inoculation and the importance of field testing, following hydroponic screening, to verify the resistance to soil-supplied stresses.

  10. The effects of sequential exposure to acidic fog and ozone on pulmonary function in exercising subjects

    SciTech Connect

    Aris, R.; Christian, D.; Sheppard, D.; Balmes, J.R. )

    1991-01-01

    In Southern California coastal regions, morning fog is often acidified by the presence of nitric acid (HNO{sub 3}). Peak exposure to ozone (O{sub 3}) usually occurs in the afternoon and evening, after the fog has dissipated. To determine whether fog containing HNO{sub 3} might enhance pulmonary responses to O{sub 3}, we studied a group of healthy, athletic subjects selected for lung function sensitivity to O{sub 3}. On 3 separate days, the subjects exercised for 2 h in atmospheres containing HNO{sub 3} fog (0.5 mg/ml), H{sub 2}O fog, or clean, filtered air. After a 1-h break, they exercised for an additional 3 h in an atmosphere containing 0.20 ppm O{sub 3}. Surprisingly, the mean O{sub 3}-induced decrements in FEV1 and FVC were smaller after exercise in each fog-containing atmosphere than they were after exercise in clean, filtered air. The mean (+/- SEM) O{sub 3}-induced decrements in FEV1 were 26.4 +/- 5.3% after air, 17.1 +/- 3.7% after H{sub 2}O fog, and 18.0 +/- 4.3% after HNO{sub 3} fog, and in FVC they were 19.9 +/- 4.7% after air, 13.6 +/- 2.8% after H{sub 2}O fog, and 13.6 +/- 4.2% after HNO{sub 3} fog.

  11. Influence of paternal exposure to oil and oil products on time to pregnancy and spontaneous abortions.

    PubMed

    Bull, N; Riise, T; Moen, B E

    1999-08-01

    The objective of this study was to evaluate the influence of exposure to oil and oil products among men on the time taken for their wives to conceive and on the incidence of spontaneous abortion among them. A cross-sectional study was performed by posting questionnaires to 1,269 men employed as offshore mechanics, offshore operators, offshore drilling personnel, car mechanics (the 'exposed' occupations) and carpenters ('unexposed'). The married men were asked to give a separate questionnaire to their wives for details about their pregnancies. The time elapsed between the beginning of coitus without contraception and the wife becoming pregnant (time to pregnancy) was analyzed with Cox regression analysis by calculating fecundability ratios for the pregnancies for the men exposed to oil and oil products as compared with the men who were not exposed. Spontaneous abortions were analyzed with logistic regression by calculating odds ratios for the pregnancies in which the men were exposed vs. not exposed. A total of 741 (58%) men returned the questionnaires. A total of 301 pregnancies were analyzed for time taken to conceive and 580 for spontaneous abortion. The results were adjusted for variables that could significantly influence conception time (previous infections of the reproductive system and coffee drinking) or the incidence of spontaneous abortion (mother's age, parity and smoking). The outcomes between the exposed and unexposed pregnancies showed no significant differences. Car mechanics had a lower fecundability ratio before 1992 than after 1992. Paternal exposure to hydrocarbons in the occupations studied did not seem to have had a major influence on time to conception or the incidence of spontaneous abortion among the wives of the men exposed to oil products.

  12. Exploratory study on a statistical method to analyse time resolved data obtained during nanomaterial exposure measurements

    NASA Astrophysics Data System (ADS)

    Clerc, F.; Njiki-Menga, G.-H.; Witschger, O.

    2013-04-01

    Most of the measurement strategies that are suggested at the international level to assess workplace exposure to nanomaterials rely on devices measuring, in real time, airborne particles concentrations (according different metrics). Since none of the instruments to measure aerosols can distinguish a particle of interest to the background aerosol, the statistical analysis of time resolved data requires special attention. So far, very few approaches have been used for statistical analysis in the literature. This ranges from simple qualitative analysis of graphs to the implementation of more complex statistical models. To date, there is still no consensus on a particular approach and the current period is always looking for an appropriate and robust method. In this context, this exploratory study investigates a statistical method to analyse time resolved data based on a Bayesian probabilistic approach. To investigate and illustrate the use of the this statistical method, particle number concentration data from a workplace study that investigated the potential for exposure via inhalation from cleanout operations by sandpapering of a reactor producing nanocomposite thin films have been used. In this workplace study, the background issue has been addressed through the near-field and far-field approaches and several size integrated and time resolved devices have been used. The analysis of the results presented here focuses only on data obtained with two handheld condensation particle counters. While one was measuring at the source of the released particles, the other one was measuring in parallel far-field. The Bayesian probabilistic approach allows a probabilistic modelling of data series, and the observed task is modelled in the form of probability distributions. The probability distributions issuing from time resolved data obtained at the source can be compared with the probability distributions issuing from the time resolved data obtained far-field, leading in a

  13. Influence of paternal exposure to oil and oil products on time to pregnancy and spontaneous abortions.

    PubMed

    Bull, N; Riise, T; Moen, B E

    1999-08-01

    The objective of this study was to evaluate the influence of exposure to oil and oil products among men on the time taken for their wives to conceive and on the incidence of spontaneous abortion among them. A cross-sectional study was performed by posting questionnaires to 1,269 men employed as offshore mechanics, offshore operators, offshore drilling personnel, car mechanics (the 'exposed' occupations) and carpenters ('unexposed'). The married men were asked to give a separate questionnaire to their wives for details about their pregnancies. The time elapsed between the beginning of coitus without contraception and the wife becoming pregnant (time to pregnancy) was analyzed with Cox regression analysis by calculating fecundability ratios for the pregnancies for the men exposed to oil and oil products as compared with the men who were not exposed. Spontaneous abortions were analyzed with logistic regression by calculating odds ratios for the pregnancies in which the men were exposed vs. not exposed. A total of 741 (58%) men returned the questionnaires. A total of 301 pregnancies were analyzed for time taken to conceive and 580 for spontaneous abortion. The results were adjusted for variables that could significantly influence conception time (previous infections of the reproductive system and coffee drinking) or the incidence of spontaneous abortion (mother's age, parity and smoking). The outcomes between the exposed and unexposed pregnancies showed no significant differences. Car mechanics had a lower fecundability ratio before 1992 than after 1992. Paternal exposure to hydrocarbons in the occupations studied did not seem to have had a major influence on time to conception or the incidence of spontaneous abortion among the wives of the men exposed to oil products. PMID:10628044

  14. Dietary Fatty Acids: Is it Time to Change the Recommendations?

    PubMed

    Nettleton, Joyce A; Lovegrove, Julie A; Mensink, Ronald P; Schwab, Ursula

    2016-01-01

    Limiting the saturated fatty acid (SAFA) consumption forms the basis of dietary fat recommendations for heart health, despite several meta-analyses demonstrating no link between dietary SAFA and the risk of cardiovascular disease (CVD). Three experts on dietary fat and health discussed the evidence of reducing SAFA intake at a symposium of the Federation of European Nutrition Societies in Berlin, Germany, October 23, 2015. Ronald P. Mensink, Maastricht University, the Netherlands, discussed the evidence linking dietary fatty acids and CVD risk. He emphasized the importance of the replacement nutrient(s) when SAFA intake is reduced. Julie Lovegrove, University of Reading, UK, addressed the question of whether higher intakes of unsaturated fatty acids are beneficial. She discussed the replacement of SAFA by polyunsaturated fatty acids (PUFA) and monounsaturated fatty acids (MUFA), noting the reduction in CVD risk with PUFA replacement and in CVD risk markers with MUFA replacement of SAFA. Ursula Schwab, University of Eastern Finland, Kuopio, Finland, discussed the importance of dietary patterns in achieving reduced risk of CVD, observing that several dietary patterns following the principles of a health-promoting diet and adapted to local customs, food preferences and seasonality are effective in reducing the risk of CVD, type 2 diabetes and other chronic diseases. This paper summarizes the symposium presentations. PMID:27251664

  15. Critical time delay of the pineal melatonin rhythm in humans due to weak electromagnetic exposure.

    PubMed

    Halgamuge, Malka N

    2013-08-01

    Electromagnetic fields (EMFs) can increase free radicals, activate the stress response and alter enzyme reactions. Intracellular signalling is mediated by free radicals and enzyme kinetics is affected by radical pair recombination rates. The magnetic field component of an external EMF can delay the "recombination rate" of free radical pairs. Magnetic fields thus increase radical life-times in biological systems. Although measured in nanoseconds, this extra time increases the potential to do more damage. Melatonin regulates the body's sleep-wake cycle or circadian rhythm. The World Health Organization (WHO) has confirmed that prolonged alterations in sleep patterns suppress the body's ability to make melatonin. Considerable cancer rates have been attributed to the reduction of melatonin production as a result of jet lag and night shift work. In this study, changes in circadian rhythm and melatonin concentration are observed due to the external perturbation of chemical reaction rates. We further analyze the pineal melatonin rhythm and investigate the critical time delay or maturation time of radical pair recombination rates, exploring the impact of the mRNA degradation rate on the critical time delay. The results show that significant melatonin interruption and changes to the circadian rhythm occur due to the perturbation of chemical reaction rates, as also reported in previous studies. The results also show the influence of the mRNA degradation rate on the circadian rhythm's critical time delay or maturation time. The results support the hypothesis that exposure to weak EMFs via melatonin disruption can adversely affect human health.

  16. Ameloglyphics: A possible forensic tool for person identification following high temperature and acid exposure

    PubMed Central

    Juneja, Manjushree; Juneja, Saurabh; Rakesh, Nagaraju; Bhoomareddy Kantharaj, Yashoda Devi

    2016-01-01

    Introduction: Forensic odontology is a branch that is evolving over time and has opened newer avenues that may help in the identification of individuals. Tooth prints are the enamel rod end patterns on tooth surface and they are considered as a hard tissue analog to fingerprints. Teeth have the highest resistance to most environmental effects like fire, desiccation, and decomposition, and may be used as a forensic evidence. Aims and Objectives: The aim of the study was to evaluate if the tooth prints could be used for an individual's identification and reproducibility and permanency of these tooth prints after exposing the teeth to acid and various degrees of temperature. Materials and Methods: 90 tooth prints from 20 freshly extracted maxillary premolar teeth were obtained. Cellophane tape technique was used to record enamel rod end patterns on tooth surface. Ten teeth (one from each patient) were immersed in 36.46% hydrochloric acid and the tooth prints were obtained at various intervals (5 min, 10 min, and 20 min). The other 10 teeth (one from each patient) were incinerated and impression was made at various intervals (80° C, 400° C, 600° C, and 750° C). Tooth prints obtained from different teeth (total of 90 tooth prints) were analyzed using Verifinger® standard SDK version 5.0 software. Results: All the 20 original tooth prints were distinct from each other and no inter-individual or intra-individual similarity was found. The tooth prints from the same tooth after it was exposed to acid or heat were reproducible and showed high to very high similarity with the original tooth print of that particular tooth stored in the database. Conclusion: Tooth prints may be used as an effective aid in person identification even in adverse conditions such as burn and acid attack injuries. PMID:27051220

  17. Shear bond strength of metallic brackets photo-activated with light-emitting diode (LED) at different exposure times.

    PubMed

    Rêgo, Emanuel Braga; Romano, Fábio Lourenço

    2007-10-01

    The purpose of this study was to compare the shear bond strength of orthodontic metallic brackets photo-activated with two different light-curing sources at different exposure times: halogen light (XL 1500, 3M ESPE) and LED light (Ortholux, 3M Unitek). Sixty bovine permanent lower incisors were inserted into PVC tubes containing plaster. The buccal surfaces were cleaned with pumice and water, and then etched with 37% phosphoric acid gel. The XT Primer bonding agent (3M Unitek) was applied to the enamel surfaces and the metallic pre-coated brackets (Transbond APC II system, 3M Unitek) were attached to upper central incisors. The teeth were randomly divided into four groups (n=15). In Group I (Control), halogen light was used for 40 seconds, while in Groups II, III, and IV were light-cured with LED light unit for 40, 10, and 5 seconds, respectively. The teeth were stored in distilled water at 37 degrees C for 24 hours. The brackets were submitted to shear bond strength test in universal testing machine (Instron) at a crosshead speed of 0.5 mm/minute. Shear bond strength means (MPa) were 4.87 for Group I; 5.89 for Group II; 4.83 for Group III, and 4.39 for Group IV. Tukey's test detected no statistically significant differences among the groups regarding the shear bond strength (p>0.05). Neither of the types of light-curing sources or exposure times influenced the shear bond strength of metallic brackets. PMID:19089170

  18. SHEAR BOND STRENGTH OF METALLIC BRACKETS PHOTO-ACTIVATED WITH LIGHT-EMITTING DIODE (LED) AT DIFFERENT EXPOSURE TIMES

    PubMed Central

    Rêgo, Emanuel Braga; Romano, Fábio Lourenço

    2007-01-01

    The purpose of this study was to compare the shear bond strength of orthodontic metallic brackets photo-activated with two different light-curing sources at different exposure times: halogen light (XL 1500, 3M ESPE) and LED light (Ortholux, 3M Unitek). Sixty bovine permanent lower incisors were inserted into PVC tubes containing plaster. The buccal surfaces were cleaned with pumice and water, and then etched with 37% phosphoric acid gel. The XT Primer bonding agent (3M Unitek) was applied to the enamel surfaces and the metallic pre-coated brackets (Transbond APC II system, 3M Unitek) were attached to upper central incisors. The teeth were randomly divided into four groups (n=15). In Group I (Control), halogen light was used for 40 seconds, while in Groups II, III, and IV were light-cured with LED light unit for 40, 10, and 5 seconds, respectively. The teeth were stored in distilled water at 37°C for 24 hours. The brackets were submitted to shear bond strength test in universal testing machine (Instron) at a crosshead speed of 0.5 mm/minute. Shear bond strength means (MPa) were 4.87 for Group I; 5.89 for Group II; 4.83 for Group III, and 4.39 for Group IV. Tukey's test detected no statistically significant differences among the groups regarding the shear bond strength (p>0.05). Neither of the types of light-curing sources or exposure times influenced the shear bond strength of metallic brackets. PMID:19089170

  19. Dose, exposure time, and resolution in Serial X-ray Crystallography

    SciTech Connect

    Starodub, D; Rez, P; Hembree, G; Howells, M; Shapiro, D; Chapman, H N; Fromme, P; Schmidt, K; Weierstall, U; Doak, R B; Spence, J C

    2007-03-22

    Using detailed simulation and analytical models, the exposure time is estimated for serial crystallography, where hydrated laser-aligned proteins are sprayed across a continuous synchrotron beam. The resolution of X-ray diffraction microscopy is limited by the maximum dose that can be delivered prior to sample damage. In the proposed Serial Crystallography method, the damage problem is addressed by distributing the total dose over many identical hydrated macromolecules running continuously in a single-file train across a continuous X-ray beam, and resolution is then limited only by the available fluxes of molecules and X-rays. Orientation of the diffracting molecules is achieved by laser alignment. We evaluate the incident X-ray fluence (energy/area) required to obtain a given resolution from (1) an analytical model, giving the count rate at the maximum scattering angle for a model protein, (2) explicit simulation of diffraction patterns for a GroEL-GroES protein complex, and (3) the frequency cut off of the transfer function following iterative solution of the phase problem, and reconstruction of a density map in the projection approximation. These calculations include counting shot noise and multiple starts of the phasing algorithm. The results indicate the number of proteins needed within the beam at any instant for a given resolution and X-ray flux. We confirm an inverse fourth power dependence of exposure time on resolution, with important implications for all coherent X-ray imaging. We find that multiple single-file protein beams will be needed for sub-nanometer resolution on current third generation synchrotrons, but not on fourth generation designs, where reconstruction of secondary protein structure at a resolution of 7 {angstrom} should be possible with short (below 100 s) exposures.

  20. REAL-TIME MODELING AND MEASUREMENT OF MOBILE SOURCE POLLUTANT CONCENTRATIONS FOR ESTIMATING HUMAN EXPOSURES IN COMMUNITIES NEAR ROADWAYS

    EPA Science Inventory

    The United States Environmental Protection Agency's (EPA) National Exposure Research Laboratory (NERL) is pursuing a project to improve the methodology for real-time site specific modeling of human exposure to pollutants from motor vehicles. The overall project goal is to deve...

  1. The Impact of the Developmental Timing of Trauma Exposure on PTSD Symptoms and Psychosocial Functioning among Older Adults

    ERIC Educational Resources Information Center

    Ogle, Christin M.; Rubin, David C.; Siegler, Ilene C.

    2013-01-01

    The present study examined the impact of the developmental timing of trauma exposure on posttraumatic stress disorder (PTSD) symptoms and psychosocial functioning in a large sample of community-dwelling older adults (N = 1,995). Specifically, we investigated whether the negative consequences of exposure to traumatic events were greater for traumas…

  2. Applicability of Travel- and Exposure-Time Concepts to Nonlinear Bioreactive Transport in Groundwater

    NASA Astrophysics Data System (ADS)

    Arie Cirpka, Olaf; Sanz-Prat, Alicia; Loschko, Matthias; Finkel, Michael; Lu, Chuanhe

    2016-04-01

    Travel-time based concepts of modeling subsurface transport have been established as computationally efficient alternatives to spatially explicit simulation methods. The spatial coordinates are replaced by travel time, resulting in one-dimensional transport with a constant „velocity" of unity. The concept is straight forward in linear transport applications, and under these conditions the results are exact provided that the coefficients of linear transport don't vary in space. In nonlinear transport, mixing can jeopardize the validity of the approach. This holds particularly true for transverse mixing, exchanging solute mass between streamtubes. We have performed systematic analyses of nonlinear bioreactive transport, involving oxygen, nitrate, organic carbon, as well as aerobic and denitrifying bacteria to analyzed under which conditions the errors introduced by travel-time and similar formulations are negligible. In steady-state flows with uniform reactive parameters, an excellent agreement between multi-dimensional reactive transport results, affected by transverse dispersion and flow heterogeneity, and one-dimensional travel-time results could be achieved by mapping the reactive-species concentrations to the multi-dimensional domain according to the local mean groundwater age. Aliasing of local transverse dispersion to macroscopically longitudinal mixing can be addressed by using a distance-dependent longitudinal dispersion coefficient. The approach also works for transient flows as long as the direction of flow remains constant and only the magnitude varies. Under these conditions, the groundwater age for the time-averaged velocity field is an adequate mapping variable, provided that flow transients are accounted for in the one- and multi-dimensional simulations. If the reaction takes place only in specific regions, the time of exposure to the according conditions is a better predictor of reactive transport than the overall travel time. Spatially variable

  3. Potential citric acid exposure and toxicity to Hawaiian hoary bats (Lasiurus cinereus semotus) associated with Eleutherodactylus frog control.

    PubMed

    Pitt, William C; Witmer, Gary W; Jojola, Susan M; Sin, Hans

    2014-04-01

    We examined potential exposure of Hawaiian hoary bats (Lasiurus cinereus semotus) to citric acid, a minimum risk pesticide registered for control of invasive Eleutherodactylus frog populations. Hoary bats are nocturnal insectivores that roost solitarily in foliage, federally listed as endangered, and are endemic to Hawaii. Oral ingestion during grooming of contaminated fur appears to be the principal route by which these bats might be exposed to citric acid. We made assessments of oral toxicity, citric acid consumption, retention of material on fur, and grooming using big brown bats (Eptesicus fuscus) as a surrogate species. We evaluated both ground application and aerial application of 16 % solutions of citric acid during frog control operations. Absorbent bat effigies exposed to ground and aerial operational spray applications retained means of 1.54 and 0.02 g, respectively, of dry citric acid, although retention by the effigies was much higher than bat carcasses drenched in citric acid solutions. A high dose delivered orally (2,811 mg/kg) was toxic to the big brown bats and emesis occurred in 1 bat dosed as low as the 759 mg/kg level. No effect was observed with the lower doses examined (≤ 542 mg/kg). Bats sprayed with 5 ml of 16 % (w/w) citric acid solution showed no evidence of intoxication. In field situations, it is unlikely that bats would be sprayed directly or ingest much citric acid retained by fur. Based on our observations, we believe Hawaiian hoary bats to be at very low risk from harmful exposure to a toxic dose of citric acid during frog control operations.

  4. Formation of fatty acid esterified vitamin D3 in rat skin by exposure to ultraviolet radiation

    SciTech Connect

    Takada, K.

    1983-04-01

    The formation of fatty acid esters of vitamin D3 was demonstrated in rat skin exposed to artificial ultraviolet rays by using multi-dimensional high-performance liquid chromatography, ultraviolet spectrophotometry, and gas-liquid chromatography-mass spectrometry. This result indicated that the fatty acid esters of 7-dehydrocholesterol in rat skin (at least 80% of 7-dehydrocholesterol in rat skin is esterified) is also isomerized into vitamin D3 ester in vivo. The initial percentage of the esterified form was 84.3% and this did not significantly change up to the time when about half of the skin total vitamin D3 disappeared (2 days). Consequently, it was speculated that the vitamin D3 ester was delivered into the blood circulation from skin without having been hydrolyzed. This was supported by the presence of vitamin D3 ester in rat plasma exposed to ultraviolet radiation. In addition, in connection with the study of the restriction of vitamin D3 synthesis, distribution of total vitamin D3 in rat skin exposed to ultraviolet irradiation in vivo was compared with that in isolated skin exposed to ultraviolet radiation. The dermal layer of the isolated skin contained about 4 times more total vitamin D3 than that of in vivo skin. This finding suggests not only that ultraviolet rays could not penetrate deeply into the in vivo skin, but that the restriction of cutaneous synthesis of vitamin D3 observed in vivo may arise from this reduced penetration of ultraviolet rays.

  5. Prototype adaptive bow-tie filter based on spatial exposure time modulation

    NASA Astrophysics Data System (ADS)

    Badal, Andreu

    2016-03-01

    In recent years, there has been an increased interest in the development of dynamic bow-tie filters that are able to provide patient-specific x-ray beam shaping. We introduce the first physical prototype of a new adaptive bow-tie filter design based on the concept of "spatial exposure time modulation." While most existing bow-tie filters operate by attenuating the radiation beam differently in different locations using partially attenuating objects, the presented filter shapes the radiation field using two movable completely radio-opaque collimators. The aperture and speed of the collimators is modulated in synchrony with the x-ray exposure to selectively block the radiation emitted to different parts of the object. This mode of operation does not allow the reproduction of every possible attenuation profile, but it can reproduce the profile of any object with an attenuation profile monotonically decreasing from the center to the periphery, such as an object with an elliptical cross section. Therefore, the new adaptive filter provides the same advantages as the currently existing static bow-tie filters, which are typically designed to work for a pre-determined cylindrical object at a fixed distance from the source, and provides the additional capability to adapt its performance at image acquisition time to better compensate for the actual diameter and location of the imaged object. A detailed description of the prototype filter, the implemented control methods, and a preliminary experimental validation of its performance are presented.

  6. In vitro protoscolicidal effects of various concentrations of Ziziphora tenuior L. extract at different exposure times

    PubMed Central

    Shahnazi, Mojtaba; Azadmehr, Abbas; Latifi, Robabeh; Hajiaghaee, Reza; Saraei, Mehrzad; Alipour, Mahmood

    2016-01-01

    Objective: Hydatidosis is one of the most important zoonotic diseases and surgery is still the main treatment for this problem. One of the side effects of hydatid cyst surgery is recurrence, thus, searching and assessment of some new agents such as medicinal plant extracts are very important. In the present study, the scolicidal effect of ethanolic extract of Ziziphora tenuior (Z. tenuior) was investigated. Materials and Methods: Protoscolices were aseptically collected from sheep livers containing hydatid cyst and used in the experiments. Z. tenuior extract was used at concentration of 3-100 mg/ml for 10-60 min. Viability of protoscolices was determined by 0.1% eosin staining. Results: Based on our results, Z. tenuior extract at concentration of 10 mg/ml killed all protoscolices after 20 min. However, this medicinal plant at concentration of 25 mg/ml destroyed all protoscolices in a shorter exposure time (10 min). Therefore, the scolicidal activity of the extract at 10 and 25 mg/ml concentrations was considerably effective in lower concentrations and shorter exposure times. Conclusion: The findings of this study showed that the ethanolic extract of Z. tenuior produces high scolicidal activity; it may be used as an appropriate and effective scolicidal agent in hydatidosis surgery. This is the first report on the protoscolicidal activity of Z. tenuior. PMID:27516978

  7. Real-time imaging of membrane potentials during exposure to nanosecond pulsed electric fields

    NASA Astrophysics Data System (ADS)

    Kolb, Juergen F.; Frey, Wolfgang; White, Jody A.; Price, R. O.; Blackmore, Peter F.; Beebe, Stephen J.; Joshi, Ravindra P.; Schoenbach, Karl H.

    2005-04-01

    The charging of mammalian cell plasma membranes in response to ultrashort pulsed electric fields of 60 ns and field strengths up to 100 kV/cm was investigated. Membranes of Jurkat cells were stained with a potential-sensitive dye, Annine-6 and placed in a microreactor mounted on an inverted fluorescence microscope. Images of changes in the fluorescence intensity during the exposure were recorded with a high-sensitivity CCD-camera. A temporal resolution of 5 ns was achieved by illuminating the cells with a 5 ns laser pulse from a dye-laser. The laser pulse was synchronized with the high voltage pulse to record images at specific times before, during and after exposure to the electric field. When exposing Jurkat cells to a 60 ns, 100 kV/cm pulse, each hemisphere of the plasma membrane (as oriented with respect to the electrodes) responded uniquely to the applied field. From these observations it is possible to draw conclusions on the charging time of the membrane, maximum transmembrane voltages and the onset of poration.

  8. Fatty acid profiles as a potential lipidomic biomarker of exposure to brevetoxin for endangered Florida manatees (Trichechus manatus latirostris).

    PubMed

    Wetzel, Dana L; Reynolds, John E; Sprinkel, Jay M; Schwacke, Lori; Mercurio, Philip; Rommel, Sentiel A

    2010-11-15

    Fatty acid signature analysis (FASA) is an important tool by which marine mammal scientists gain insight into foraging ecology. Fatty acid profiles (resulting from FASA) represent a potential biomarker to assess exposure to natural and anthropogenic stressors. Florida manatees are well studied, and an excellent necropsy program provides a basis against which to assess this budding tool. Results using samples from 54 manatees assigned to four cause-of-death categories indicated that those animals exposed to or that died due to brevetoxin exposure (red tide, or RT samples) demonstrate a distinctive hepatic fatty acid profile. Discriminant function analysis indicated that hepatic fatty acids could be used to classify RT versus non-RT liver samples with reasonable certainty. A discriminant function was derived based on 8 fatty acids which correctly classified 100% of samples from a training dataset (10 RT and 25 non-RT) and 85% of samples in a cross-validation dataset (5 RT and 13 non-RT). Of the latter dataset, all RT samples were correctly classified, but two of thirteen non-RT samples were incorrectly classified. However, the "incorrect" samples came from manatees that died due to other causes during documented red tide outbreaks; thus although the proximal cause of death was due to watercraft collisions, exposure to brevetoxin may have affected these individuals in ways that increased their vulnerability. This use of FASA could: a) provide an additional forensic tool to help scientists and managers to understand cause of death or debilitation due to exposure to red tide in manatees; b) serve as a model that could be applied to studies to improve assessments of cause of death in other marine mammals; and c) be used, as in humans, to help diagnose metabolic disorders or disease states in manatees and other species.

  9. Fatty acid profiles as a potential lipidomic biomarker of exposure to brevetoxin for endangered Florida manatees (Trichechus manatus latirostris).

    PubMed

    Wetzel, Dana L; Reynolds, John E; Sprinkel, Jay M; Schwacke, Lori; Mercurio, Philip; Rommel, Sentiel A

    2010-11-15

    Fatty acid signature analysis (FASA) is an important tool by which marine mammal scientists gain insight into foraging ecology. Fatty acid profiles (resulting from FASA) represent a potential biomarker to assess exposure to natural and anthropogenic stressors. Florida manatees are well studied, and an excellent necropsy program provides a basis against which to assess this budding tool. Results using samples from 54 manatees assigned to four cause-of-death categories indicated that those animals exposed to or that died due to brevetoxin exposure (red tide, or RT samples) demonstrate a distinctive hepatic fatty acid profile. Discriminant function analysis indicated that hepatic fatty acids could be used to classify RT versus non-RT liver samples with reasonable certainty. A discriminant function was derived based on 8 fatty acids which correctly classified 100% of samples from a training dataset (10 RT and 25 non-RT) and 85% of samples in a cross-validation dataset (5 RT and 13 non-RT). Of the latter dataset, all RT samples were correctly classified, but two of thirteen non-RT samples were incorrectly classified. However, the "incorrect" samples came from manatees that died due to other causes during documented red tide outbreaks; thus although the proximal cause of death was due to watercraft collisions, exposure to brevetoxin may have affected these individuals in ways that increased their vulnerability. This use of FASA could: a) provide an additional forensic tool to help scientists and managers to understand cause of death or debilitation due to exposure to red tide in manatees; b) serve as a model that could be applied to studies to improve assessments of cause of death in other marine mammals; and c) be used, as in humans, to help diagnose metabolic disorders or disease states in manatees and other species. PMID:20880571

  10. Endocrine disruption effects of long-term exposure to perfluorodecanoic acid (PFDA) and perfluorotridecanoic acid (PFTrDA) in zebrafish (Danio rerio) and related mechanisms.

    PubMed

    Jo, Areum; Ji, Kyunghee; Choi, Kyungho

    2014-08-01

    Perfluoroalkyl acids (PFAAs) have been frequently detected in both the environment and biota, however the endocrine disruption potentials and underlying mechanism of long-chain PFAAs have not yet been fully understood in fish. In the present study, the effects of perfluorodecanoic acid (PFDA) and perfluorotridecanoic acid (PFTrDA) on sex steroid hormones and expression of mRNA of selected genes in hypothalamic-pituitary-gonad (HPG) axis were evaluated after 120 d exposure of zebrafish. In addition, production of sex hormones and transcription of steroidogenic genes were measured after in vitro exposure of H295R cells for 48 h. Exposure to PFTrDA resulted in reduced production of testosterone (T) along with lesser expression of CYP17A mRNA in H295R cells. In zebrafish, significant up-regulation of vtg1 was observed in males exposed to PFDA, whereas down-regulation was observed in females exposed to PFTrDA. In male zebrafish, concentrations of 17β-estradiol (E2) were significantly increased at 0.01 mg L(-1) PFTrDA. Significant increases in ratios of E2/T and E2/11-ketotestosterone (11-KT) were observed in male zebrafish after exposure to PFDA or PFTrDA, indicating estrogenic potentials of these compounds. The results of this study showed that long-term exposure to PFDA or PFTrDA could modulate sex steroid hormone production and related gene transcription of the HPG axis in a sex-dependent manner. Consequences of endocrine disruptions in reproduction performances of the fish warrant further investigation.

  11. Does developmental exposure to perflurooctanoic acid (PFOA) induce immunopathologies commonly observed in neurodevelopmental disorders?

    PubMed

    Hu, Qing; Franklin, Jason N; Bryan, Ian; Morris, Erin; Wood, Andrew; DeWitt, Jamie C

    2012-12-01

    Immune comorbidities often are reported in subsets of patients with neurodevelopmental disorders, including autism spectrum disorders and attention-deficit hyperactivity disorder. A common immunopathology is an increase in serum autoantibodies against myelin basic protein (MBP) relative to control patients. Increases in autoantibodies suggest possible deficits in self-tolerance that may contribute to the formation of brain-specific autoantibodies and subsequent effects on the central nervous system (CNS). Oppositely, the formation of neuronal autoantibodies may be a reaction to neuronal injury or damage. Perfluorooctanoic acid (PFOA) is an environmental pollutant that induces multisystem toxicity in rodent models, including immunotoxicity and neurotoxicity. We hypothesized that developmental exposure to PFOA may induce immunotoxicity similar to that observed in subsets of patients with neurodevelopmental disorders. To test this hypothesis, we evaluated subsets of T cells from spleens, serum markers of autoreactivity, and levels of MBP and T cell infiltration in the cerebella of adult offspring exposed to 0.02, 0.2, or 2mg/kg of PFOA given to dams from gestation through lactation. Litter weights of offspring from dams exposed to 2mg/kg of PFOA were reduced by 32.6%, on average, from postnatal day one (PND1) through weaning (PND21). The percentage of splenic CD4+CD25+Foxp3+ T cells in male and female offspring from dams exposed to 2mg/kg of PFOA was reduced by 22% relative to the control percentage. Ex vivo co-cultures of splenic CD4+CD25+ T cells and CD4+CD25- T cells from dosed male offspring produced less IL-10 relative to control cells. Anti-ssDNA, a serum marker of autoreactivity, was decreased by 26%, on average, in female offspring from dams exposed to 0.02 and 2mg/kg PFOA. No other endpoints were statistically different by dose. These data suggest that developmental PFOA exposure may impact T cell responses and may be a possible route to downstream effects on

  12. Solar Ion Processing of Itokawa Grains: Constraints on Surface Exposure Times

    NASA Technical Reports Server (NTRS)

    Christoffersen, R.; Keller, L. P.

    2015-01-01

    Analytical TEM observations obtained to date reveal that a significant sub-population of grains returned from the surface of asteroid Itokawa have had their outer 30-100 nm processed by space weathering effects. Although the effects include some surface deposition of condensed impact vapor and isolated impact melt splashes, much of the width of the space weathered outer margins or "rims" on grains is derived from solar wind processing of the original host grain. Similar to what has long been reported for some lunar grains, the ion-processed rims on Itokawa grains exhibit varing degrees and depths of penetration of atomic-displacement ion damage, resulting in complete amorphization for some rims (particularly in plagioclase), or formation of highly defective but still crystalline structures in others (particularly in pyroxene and olivine). Possibly different from lunar grains, however, is the presence of isolated internal cavities or voids in Itokawa grain rims, which may be implantation "bubbles" due to accumulating implanted solar wind H and/or He. For a given mineral exposed at a particular set of long term solar wind conditions, the level of ion damage in a given grain rim, the depth of damage penetration represented by the rim width, and the formation or lack of formation of implantation bubbles can all be linked to the time spent by the grain in an uncovered state on the topmost, space-exposed, regolith surface. For the lunar case, we have previously shown that with reasonable assumptions about solar wind characteristics over time, a model can be developed to estimate this exposure time based on the width of amorphous rims on lunar grains. Here we report on an expansion of the model to cover exposure time information contained in the array of solar ion-induced features in Itokawa grains.

  13. Controlling silver nanoparticle exposure in algal toxicity testing – A matter of timing

    PubMed Central

    Baun, Anders

    2015-01-01

    The aquatic ecotoxicity testing of nanoparticles is complicated by unstable exposure conditions resulting from various transformation processes of nanoparticles in aqueous suspensions. In this study, we investigated the influence of exposure timing on the algal test response to silver nanoparticles (AgNPs), by reducing the incubation time and by aging the AgNPs in algal medium prior to testing. The freshwater green algae Pseudokirchneriella subcapitata were exposed to AgNO3, NM-300 K (a representative AgNP) and citrate stabilized AgNPs from two different manufacturers (AgNP1 and AgNP2) in a standard algal growth inhibition test (ISO 8692:2004) for 48 h and a short-term (2 h) 14C-assimilation test. For AgNO3, similar responses were obtained in the two tests, whereas freshly prepared suspensions of citrate stabilized AgNPs were less toxic in the 2-h tests compared to the 48-h tests. The 2-h test was found applicable for dissolved silver, but yielded non-monotonous concentration–response relationships and poor reproducibility for freshly prepared AgNP suspensions. However, when aging AgNPs in algal medium 24 h prior to testing, clear concentration–response patterns emerged and reproducibility increased. Prolonged aging to 48 h increased toxicity in the 2-h tests whereas aging beyond 48 h reduced toxicity. Our results demonstrate that the outcome of algal toxicity testing of AgNPs is highly influenced not only by the test duration, but also by the time passed from the moment AgNPs are added to the test medium. This time-dependency should be considered when nanomaterial dispersion protocols for ecotoxicity testing are developed. PMID:24842597

  14. Effects of Low Level Lead Exposure on Associative Learning and Memory in the Rat: Influences of Sex and Developmental Timing Of Exposure

    PubMed Central

    Anderson, D.W.; Mettil, W.; Schneider, J.S.

    2016-01-01

    Lead (Pb) exposure during development impairs a variety of cognitive, behavioral and neurochemical processes resulting in deficits in learning, memory, attention, impulsivity and executive function. Numerous studies have attempted to model this effect of Pb in rodents, with the majority of studies focusing on hippocampus-associated spatial learning and memory processes. Using a different paradigm, trace fear conditioning, a process requiring coordinated integration of both the medial prefrontal cortex and the hippocampus, we have assessed the effects of Pb exposure on associative learning and memory. The present study examined both female and male Long Evans rats exposed to three environmentally relevant levels of Pb (150 ppm, 375 ppm and 750 ppm) during different developmental periods: perinatal (PERI; gestation – postnatal day 21), early postnatal (EPN; postnatal days 1–21) and late postnatal (LPN; postnatal days 1–55). Testing began at postnatal day 55 and consisted of a single day of acquisition training, and three post training time points (1, 2 and 10 days) to assess memory consolidation and recall. All animals, regardless of sex, developmental window or level of Pb-exposure, successfully acquired conditioned-unconditioned stimulus association during training. However, there were significant effects of Pb-exposure on consolidation and memory recall at days 1–10 post training. In females, EPN and LPN exposure to 150 ppm Pb (but not PERI exposure) significantly impaired recall. In contrast, only PERI 150 ppm and 750 ppm-exposed males had significant recall deficits. These data suggest a complex interaction between sex, developmental window of exposure and Pb-exposure level on consolidation and recall of associative memories. PMID:26812500

  15. Effects of low level lead exposure on associative learning and memory in the rat: Influences of sex and developmental timing of exposure.

    PubMed

    Anderson, D W; Mettil, W; Schneider, J S

    2016-03-30

    Lead (Pb) exposure during development impairs a variety of cognitive, behavioral and neurochemical processes resulting in deficits in learning, memory, attention, impulsivity and executive function. Numerous studies have attempted to model this effect of Pb in rodents, with the majority of studies focusing on hippocampus-associated spatial learning and memory processes. Using a different paradigm, trace fear conditioning, a process requiring coordinated integration of both the medial prefrontal cortex and the hippocampus, we have assessed the effects of Pb exposure on associative learning and memory. The present study examined both female and male long evans rats exposed to three environmentally relevant levels of Pb (150 ppm, 375 ppm and 750 ppm) during different developmental periods: perinatal (PERI; gestation-postnatal day 21), early postnatal (EPN; postnatal days 1-21) and late postnatal (LPN; postnatal days 1-55). Testing began at postnatal day 55 and consisted of a single day of acquisition training, and three post training time points (1, 2 and 10 days) to assess memory consolidation and recall. All animals, regardless of sex, developmental window or level of Pb-exposure, successfully acquired conditioned-unconditioned stimulus association during training. However, there were significant effects of Pb-exposure on consolidation and memory recall at days 1-10 post training. In females, EPN and LPN exposure to 150 ppm Pb (but not PERI exposure) significantly impaired recall. In contrast, only PERI 150 ppm and 750 ppm-exposed males had significant recall deficits. These data suggest a complex interaction between sex, developmental window of exposure and Pb-exposure level on consolidation and recall of associative memories.

  16. Change of exposure response over time and long-term risk of silicosis among a cohort of Chinese pottery workers.

    PubMed

    Sun, Yi; Bochmann, Frank; Morfeld, Peter; Ulm, Kurt; Liu, Yuewei; Wang, Heijiao; Yang, Lei; Chen, Weihong

    2011-07-01

    An analysis was conducted on a cohort of Chinese pottery workers to estimate the exposure-response relationship between respirable crystalline silica dust exposure and the incidence of radiographically diagnosed silicosis, and to estimate the long-term risk of developing silicosis until the age of 65. The cohort comprised 3,250 employees with a median follow-up duration of around 37 years. Incident cases of silicosis were identified via silicosis registries (Chinese X-ray stage I, similar to International Labor Organisation classification scheme profusion category 1/1). Individual exposure to respirable crystalline silica dust was estimated based on over 100,000 historical dust measurements. The association between dust exposure, incidence and long-time risk of silicosis was quantified by Poisson regression analysis adjusted for age and smoking. The risk of silicosis depended not only on the cumulative respirable crystalline silica dust exposures, but also on the time-dependent respirable crystalline silica dust exposure pattern (long-term average concentration, highest annual concentration ever experienced and time since first exposure). A long-term "excess" risk of silicosis of approximately 1.5/1,000 was estimated among workers with all annual respirable crystalline silica dust concentration estimates less than 0.1 mg/m(3), using the German measurement strategy. This study indicates the importance of proper consideration of exposure information in risk quantification in epidemiological studies.

  17. Mycosporine-like amino acids in planktonic organisms living under different UV exposure conditions in Patagonian lakes.

    PubMed

    Tartarotti, Barbara; Baffico, Gustavo; Temporetti, Pedro; Zagarese, Horacio E

    2004-07-01

    Mycosporine-like amino acids (MAAs) were studied in zooplankton from 13 Argentinian lakes covering a broad range in altitude, maximum depth and physico-chemical properties of the water. Four to nine different MAAs (predominantly porphyra-334 and shinorine) were found in the copepods Boeckella gibbosa, B. gracilipes, B. meteoris and Parabroteas sarsi, and in the ciliate Stentor amethystinus, while MAAs were undetectable in the cladoceran Daphnia middendorffiana. Among the different copepods, maximum MAA concentrations accounted for 0.25-1.31% of the dry weight, and contents were generally about three to seven times (up to 43 times) higher in the animals living in the clearest lakes compared to those occurring in low-UV systems. This variability in the content of MAAs was related to the lake altitude (r(2) = 0.71), and the fraction of the water column to which 1% of the surface UV radiation at 320 nm penetrated (r(2) = 0.57). Our data therefore underscore the role of MAAs as sunscreens to decrease the potential negative effects of solar radiation, but they also indicate that other environmental factors besides UV transparency play a role in determining MAA concentrations. One lake was selected to obtain additional information on the qualitative composition of MAAs in seston of <100 μm between two sampling sites and over a 2 month study period (austral summer). Six different MAAs were detected in the samples, with porphyra-334 and palythine being predominant. In the copepods collected simultaneously, there was low variation in MAA concentrations between the two sites and over time. Thus, our results suggest that under similar UV exposure conditions MAA contents of planktonic organisms show low temporal variation. PMID:21258622

  18. Mycosporine-like amino acids in planktonic organisms living under different UV exposure conditions in Patagonian lakes

    PubMed Central

    TARTAROTTI, BARBARA; BAFFICO, GUSTAVO; TEMPORETTI, PEDRO; ZAGARESE, HORACIO E.

    2011-01-01

    Mycosporine-like amino acids (MAAs) were studied in zooplankton from 13 Argentinian lakes covering a broad range in altitude, maximum depth and physico-chemical properties of the water. Four to nine different MAAs (predominantly porphyra-334 and shinorine) were found in the copepods Boeckella gibbosa, B. gracilipes, B. meteoris and Parabroteas sarsi, and in the ciliate Stentor amethystinus, while MAAs were undetectable in the cladoceran Daphnia middendorffiana. Among the different copepods, maximum MAA concentrations accounted for 0.25–1.31% of the dry weight, and contents were generally about three to seven times (up to 43 times) higher in the animals living in the clearest lakes compared to those occurring in low-UV systems. This variability in the content of MAAs was related to the lake altitude (r2 = 0.71), and the fraction of the water column to which 1% of the surface UV radiation at 320 nm penetrated (r2 = 0.57). Our data therefore underscore the role of MAAs as sunscreens to decrease the potential negative effects of solar radiation, but they also indicate that other environmental factors besides UV transparency play a role in determining MAA concentrations. One lake was selected to obtain additional information on the qualitative composition of MAAs in seston of <100 μm between two sampling sites and over a 2 month study period (austral summer). Six different MAAs were detected in the samples, with porphyra-334 and palythine being predominant. In the copepods collected simultaneously, there was low variation in MAA concentrations between the two sites and over time. Thus, our results suggest that under similar UV exposure conditions MAA contents of planktonic organisms show low temporal variation. PMID:21258622

  19. Ultrasonication and the quality of human milk: variation of power and time of exposure.

    PubMed

    Christen, Lukas; Lai, Ching Tat; Hartmann, Peter E

    2012-08-01

    Donor human milk is pasteurized to prevent the potential risk of the transmission of pathogens to preterm infants. Currently, Holder pasteurization (human milk held at 62·5°C for 30 min) is used in most human milk banks, but has the disadvantage that it results in excessive inactivation of important bioactive components. Power-ultrasound (20-100 kHz) is an emerging technology for the preservation of foods and could be an alternative method for the treatment of human milk. The aim of this study was to investigate the effect of different ultrasound settings on the elimination of Escherichia coli and the retention of bile salt stimulated lipase (BSSL) activity. Ultrasonication with a constant power decreased Esch. coli viability exponentially over time until the processing temperature increased to sub-pasteurization level to between 51·4 and 58·5°C, then a log10 1·3 decrease was observed (P<0·05). BSSL activity decreased to 91% until a temperature of 51·4°C and then it decreased to 8% between 51·4 and 64·9°C. Ultrasonication with a constant energy and various power and exposure times showed the highest temperature (53·7°C) when treated with the longest exposure time and lowest ultrasound-power (276 s at 3·62 W) compared with 37·6°C for 39 s at 25·64 W. The findings predict that the viability of Esch. coli could be reduced by log10 5 with a minimal loss of activity of BSSL by applying 13·8 kJ of energy in 12 ml of human milk using high ultrasound power over a short exposure time to ensure that the temperature remains below the critical level for protein denaturation. Alternatively, the use of lower power settings such as the 26 W used in the present studies would require a cooling system to ensure the human milk BSSL was protected against temperature denaturation.

  20. Validation of exposure time for discharge measurements made with two bottom-tracking acoustic doppler current profilers

    USGS Publications Warehouse

    Czuba, J.A.; Oberg, K.

    2008-01-01

    Previous work by Oberg and Mueller of the U.S. Geological Survey in 2007 concluded that exposure time (total time spent sampling the flow) is a critical factor in reducing measurement uncertainty. In a subsequent paper, Oberg and Mueller validated these conclusions using one set of data to show that the effect of exposure time on the uncertainty of the measured discharge is independent of stream width, depth, and range of boat speeds. Analysis of eight StreamPro acoustic Doppler current profiler (ADCP) measurements indicate that they fall within and show a similar trend to the Rio Grande ADCP data previously reported. Four special validation measurements were made for the purpose of verifying the conclusions of Oberg and Mueller regarding exposure time for Rio Grande and StreamPro ADCPs. Analysis of these measurements confirms that exposure time is a critical factor in reducing measurement uncertainty and is independent of stream width, depth, and range of boat speeds. Furthermore, it appears that the relation between measured discharge uncertainty and exposure time is similar for both Rio Grande and StreamPro ADCPs. These results are applicable to ADCPs that make use of broadband technology using bottom-tracking to obtain the boat velocity. Based on this work, a minimum of two transects should be collected with an exposure time for all transects greater than or equal to 720 seconds in order to achieve an uncertainty of ??5 percent when using bottom-tracking ADCPs. ?? 2008 IEEE.

  1. Effect of dexamethasone and oxygen exposure on neonatal rat lung retinoic acid receptor proteins.

    PubMed

    McMenamy, K R; Anderson, M J; Zachman, R D

    1994-10-01

    Retinol deficiency in animal models results in histopathologic airway changes that appear similar to those found in human premature infants with bronchopulmonary dysplasia (BPD). Dexamethasone (DEX), a steroid now often used in the treatment of BPD, might potentially affect lung vitamin A homeostasis since it alters serum and liver retinoid stores in certain models. Our objective was to determine the effect of DEX on neonatal rat lung retinoid status and the binding of retinoic acid (RA) to cytosolic and nuclear receptor proteins. We examined this effect both in room air and when the animals breathed 95% oxygen (O2). Twenty-four 1-day-old rat pups received either 1 microgram/g DEX subcutaneously, an equal volume of normal saline (NS) subcutaneously at 0 (start experiment time), 24, and 48 hours, or no injection at all, and were sacrificed at 72 hours. Twelve rats in each treatment group were housed in room air and 12 in each group were exposed to > 95% O2 for the 3 day period. Lung and liver were analyzed for retinyl palmitate (RP). Nuclear retinoic acid receptor (RAR) and cellular retinoic acid binding protein (CRABP) were measured by specific binding assays. DEX decreased liver RP by 33-55% and rat pup lung RP by over 60%; it also decreased lung RAR binding (mean dpm/microgram protein +/- SEM) in both room air and oxygen groups: Air (11.2 +/- 1.0) vs. Air/DEX (4.6 +/- 1.3, n = 6; P < 0.01), and O2 (18.2 +/- 0.6) vs. O2/DEX (3.2 +/- 0.6, n = 6; P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7838622

  2. Omega-3 fatty acids prevent early-life antibiotic exposure-induced gut microbiota dysbiosis and later-life obesity.

    PubMed

    Kaliannan, K; Wang, B; Li, X-Y; Bhan, A K; Kang, J X

    2016-06-01

    Early-life antibiotic exposure can disrupt the founding intestinal microbial community and lead to obesity later in life. Recent studies show that omega-3 fatty acids can reduce body weight gain and chronic inflammation through modulation of the gut microbiota. We hypothesize that increased tissue levels of omega-3 fatty acids may prevent antibiotic-induced alteration of gut microbiota and obesity later in life. Here, we utilize the fat-1 transgenic mouse model, which can endogenously produce omega-3 fatty acids and thereby eliminates confounding factors of diet, to show that elevated tissue levels of omega-3 fatty acids significantly reduce body weight gain and the severity of insulin resistance, fatty liver and dyslipidemia resulting from early-life exposure to azithromycin. These effects were associated with a reversal of antibiotic-induced dysbiosis of gut microbiota in fat-1 mice. These results demonstrate the beneficial effects of omega-3 fatty acids on antibiotic-induced gut dysbiosis and obesity, and suggest the potential utility of omega-3 supplementation as a safe and effective means for the prevention of obesity in children who are exposed to antibiotics.

  3. Design considerations for ozone and acid aerosol exposure and health investigations: the Fairview Lake summer camp - photochemical smog case study

    SciTech Connect

    Lioy, P.J.; Spektor, D.; Thurston, G.; Citak, K.; Lippmann, M.; Bock, N.; Speizer, F.E.; Hayes, C.

    1987-01-01

    The health effects associated with ozone and acidic particulate sulfate exposures to active children have been and are being addressed in field epidemiological studies at summer camps in rural areas of the Northeastern US. The rationale and study design for studies, which have been conducted in Pennsylvania and New Jersey, are developed and reviewed. As background, results are summarized for human clinical and epidemiological studies and animal studies. These provided the basis for selection of health outcomes measured results from chemical characterization and transport studies are reviewed to define the criteria used for selection of a site which is effected by high ozone and acid species during photochemical smog episodes. The integration of the study design is discussed in detail by reviewing its application to the 1984 - Fairview Lake Camp Study (July 8 to August 4). The features of the camp study are reviewed, including the study population, pulmonary function procedures and analyses, air pollution monitoring instrumentation, and the site characteristics. The pollution exposure data are presented, for ozone and acidic sulfates and examined for the range and distribution concentration. Further information is provided on the intensity and duration of episodes encountered over the course of the study. Episodes occurred which had ozone and acid sulfates, ozone alone, and acid sulfates alone. 56 references, 9 figures.

  4. Perfluoroalkyl acids and their precursors in Swedish food: The relative importance of direct and indirect dietary exposure.

    PubMed

    Gebbink, Wouter A; Glynn, Anders; Darnerud, Per Ola; Berger, Urs

    2015-03-01

    We analyzed food market basket samples obtained in Sweden from 1999, 2005, and 2010 for perfluoroalkyl acids (PFAAs) and a range of precursor compounds. Perfluorooctane sulfonic acid (PFOS) precursors were detected in all food year pools with the highest concentrations in 1999. Six polyfluoroalkyl phosphate diesters (diPAPs, 4:2/6:2, 6:2/6:2, 6:2/8:2, 8:2/8:2, 6:2/10:2, and 10:2/10:2) were detected in the year pools with the highest ∑diPAP concentrations in 1999 and 2005. All precursors were predominantly found in meat, fish, and/or eggs based on analysis of individual food groups from 1999. Based on year pools, PFOS precursors contributed between 4 and 1% as an indirect source to total dietary PFOS intakes between 1999 and 2010. Perfluorohexanoic acid (PFHxA) exposure originated entirely from diPAPs, whereas for perfluorooctanoic acid (PFOA) and perfluorodecanoic acid (PFDA), diPAPs contributed between 1 and 19% to total exposure. The lowest precursor contributions were generally seen in food samples from 2010.

  5. Failure of Real-time Passive Notification about Radiation Exposure to Influence Physician Ordering Behavior.

    PubMed

    Polen, Lauren A; Rossi, Jennifer K; Berg, Cameron K; Balise, Raymond R; Herfkens, Robert J; Auerbach, Paul S

    2016-01-01

    Objectives  To determine whether real-time passive notification of patient radiation exposure via a computerized physician order entry system would alter the number of computed tomography scans ordered by physicians in the Emergency Department (ED) setting. Methods  When a practitioner ordered a computed tomography scan, a passive notification was immediately and prominently displayed via the computerized physician order entry system. The notification stated the following: the amount of estimated radiation in millisieverts (mSv), the equivalent number of single-view chest radiographs, and equivalent days of average environmental background radiation to which a patient during a specific computed tomography scan would be exposed. The primary outcome was changed in the number of computed tomography scans ordered when comparing data collected before and after the addition of the notification. Results  Before the dosimetry notification ("intervention") was instituted, 1,747 computed tomography scans were performed on patients during 11,709 Emergency Department visits (14.9% computed tomography scan rate). After the intervention had been instituted, 1,827 computed tomography scans were performed on patients during 11,582 Emergency Department patient visits (15.8% computed tomography scan rate). No statistically significant difference was found for all chief complaints combined (p = 0.17), or for any individual chief complaint, between the number of computed tomography scans performed on Emergency Department patients before versus after the intervention. Conclusions  Passive real-time notification of patient radiation exposure displayed in a computerized physician order entry system at the time of computed tomography scan ordering in the Emergency Department did not significantly change the number of ordered scans. PMID:27570716

  6. Failure of Real-time Passive Notification about Radiation Exposure to Influence Physician Ordering Behavior

    PubMed Central

    Polen, Lauren A; Rossi, Jennifer K; Berg, Cameron K; Balise, Raymond R; Herfkens, Robert J

    2016-01-01

    Objectives  To determine whether real-time passive notification of patient radiation exposure via a computerized physician order entry system would alter the number of computed tomography scans ordered by physicians in the Emergency Department (ED) setting. Methods  When a practitioner ordered a computed tomography scan, a passive notification was immediately and prominently displayed via the computerized physician order entry system. The notification stated the following: the amount of estimated radiation in millisieverts (mSv), the equivalent number of single-view chest radiographs, and equivalent days of average environmental background radiation to which a patient during a specific computed tomography scan would be exposed. The primary outcome was changed in the number of computed tomography scans ordered when comparing data collected before and after the addition of the notification. Results  Before the dosimetry notification (“intervention”) was instituted, 1,747 computed tomography scans were performed on patients during 11,709 Emergency Department visits (14.9% computed tomography scan rate). After the intervention had been instituted, 1,827 computed tomography scans were performed on patients during 11,582 Emergency Department patient visits (15.8% computed tomography scan rate). No statistically significant difference was found for all chief complaints combined (p = 0.17), or for any individual chief complaint, between the number of computed tomography scans performed on Emergency Department patients before versus after the intervention. Conclusions  Passive real-time notification of patient radiation exposure displayed in a computerized physician order entry system at the time of computed tomography scan ordering in the Emergency Department did not significantly change the number of ordered scans.  PMID:27570716

  7. The effect of nitric acid exposure on Galileo spacecraft titanium alloy Ti-6Al-4V propellant tanks

    NASA Technical Reports Server (NTRS)

    Hsieh, Cheng; O'Donnell, Tim; Yavrouian, Andre

    1990-01-01

    The Ti-6Al-4V-constructed retropropulsion-module tanks of the Galileo spacecraft were purged with nitrogen tetroxide in order to wait out a major launch rescheduling; nitric acid is among the residual products of such an operation. A test program was conducted on representative samples to ascertain the fracture toughness and stress corrosion threshold of the tanks' material, in view of Space Shuttle safety and mission-reliability requirements. It was found that the tanks' structural integrity was not degraded by nitric acid exposure.

  8. A preliminary estimate of the EUVE cumulative distribution of exposure time on the unit sphere. [Extreme Ultra-Violet Explorer

    NASA Technical Reports Server (NTRS)

    Tang, C. C. H.

    1984-01-01

    A preliminary study of an all-sky coverage of the EUVE mission is given. Algorithms are provided to compute the exposure of the celestial sphere under the spinning telescopes, taking into account that during part of the exposure time the telescopes are blocked by the earth. The algorithms are used to give an estimate of exposure time at different ecliptic latitudes as a function of the angle of field of view of the telescope. Sample coverage patterns are also given for a 6-month mission.

  9. Effect of concentration and cumulative exposure of inhaled sulfuric acid on tracheobronchial particle clearance in healthy humans.

    PubMed

    Spektor, D M; Yen, B M; Lippmann, M

    1989-02-01

    We have previously shown that 1-hr exposures to 0.5 microns sulfuric acid (H2SO4) mist at 100 and 1000 micrograms/m3 produced transient alterations of bronchial mucociliary clearance of monodispersed 7.6 and 4.2 microns mass median aerodynamic diameter gamma-tagged ferric oxide (Fe2O3) in healthy nonsmoking humans in a dose-dependent manner. To determine the role, if any, of the length of exposure, 10 healthy volunteers were exposed to 100 micrograms/m3 H2SO4 for 1 hr and 2 hr on separate occasions, 1 week apart, with measurements of their mucociliary clearance of 5.2 microns Fe2O3 particles inhaled both before and after the inhalation of the H2SO4. Their rate of bronchial mucociliary clearance was markedly reduced for both Fe2O3 aerosols, with slower clearance of the aerosol inhaled after the H2SO4 exposure. For the tagged Fe2O3 aerosol inhaled after exposure for 2 hr at 100 micrograms/m3 H2SO4, the tracheobronchial clearance halftime, (T50), tripled from control, and the reduced rate of clearance was still evident 3 hr after the end of exposure. The 1-hr 100 micrograms/m3 H2SO4 exposure doubled T50 from control, and the reduced rate of clearance lasted for about 2 hr after the end of exposure. These results indicate that the effect of doubling the length of exposure was as great or greater than an order of magnitude increase in the concentration of H2SO4.

  10. Preliminary investigation of effects of sublethal acid exposure on maternal behavior in the Crayfish Orconectes virilis

    SciTech Connect

    France, R.L.

    1985-11-01

    The occurrence of crayfish inhabiting the littoral regions of many oligotrophic acid sensitive lakes makes these organisms vulnerable to spring pH decreases. Egg extrusion in Orconectes spp. found in south-central Ontario is generally synchronous and occurs during or slightly after ice melting in late April, a time at which these lakes receive between 36-77% of the year's export of H from their watersheds. To understand how a toxicant affects crayfish reproduction it is necessary that the maternal and embryonic responses to experimental perturbation be separated. In an acidified lake in the Experimental Lakes Area, northwestern Ontario, 6.9-16.9% of the egg-bearing females experienced partial mortality of their broods at pH 5.4-5.6. An ancillary experiment was undertaken here to determine if this egg mortality could be a result of low pH-induced behavioral modification of the maternal female, rather than direct acid toxicity to the developing eggs.

  11. A homogeneous time-resolved fluorescence resonance energy transfer assay for phosphatidylserine exposure on apoptotic cells.

    PubMed

    Gasser, Jean-Philippe; Hehl, Michaela; Millward, Thomas A

    2009-01-01

    A simple, "mix-and-measure" microplate assay for phosphatidylserine (PtdSer) exposure on the surface of apoptotic cells is described. The assay exploits the fact that annexin V, a protein with high affinity and specificity for PtdSer, forms trimers and higher order oligomers on binding to membranes containing PtdSer. The transition from soluble monomer to cell-bound oligomer is detected using time-resolved fluorescence resonance energy transfer from europium chelate-labeled annexin V to Cy5-labeled annexin V. PtdSer detection is achieved by a single addition of a reagent mix containing labeled annexins and calcium ions directly to cell cultures in a 96-well plate, followed by a brief incubation before fluorescence measurement. The assay can be used to quantify PtdSer exposure on both suspension cells and adherent cells in situ. This method is simpler and faster than existing annexin V binding assays based on flow cytometry or microscopy, and it yields precise data with Z' values of 0.6-0.7. PMID:18835236

  12. Time of onset of necrotizing enterocolitis in newborn infants with known prenatal cocaine exposure.

    PubMed

    Lopez, S L; Taeusch, H W; Findlay, R D; Walther, F J

    1995-08-01

    Cocaine exposure can lead to diminished gut-blood supply and thereby contribute to the pathogenesis of necrotizing enterocolitis (NEC). Investigating the hypothesis that NEC occurs at a younger age in cocaine-exposed infants, we reviewed 1,284 neonatal intensive care admissions. Infants with NEC were divided into cocaine-exposed and cocaine-nonexposed groups, each subdivided into two birth-weight groups, using 1,500 g as the cutoff weight. Time of onset of NEC for each infant was determined and survival curves for the cocaine-exposed and nonexposed groups were calculated using their birth-weight subdivision. Hazard function curves were done. Neonatal risk factors in both groups were compared. Twelve percent (28/231) of cocaine-exposed infants developed NEC stage II or III versus 3% (34/1053) in the nonexposed group (P < 0.05). Eight percent of cocaine-exposed and 2% of nonexposed survivors had NEC by day 7 versus 20% and 5% by day 28 after birth (P < 0.05). Infants > 1,500 g were at risk for NEC until day 8 only, whereas infants < or = 1,500 g had both an early and continuing risk for NEC with a biphasic pattern of onset. The accentuated peak in early-onset NEC may be attributed to antenatal cocaine exposure, while late-onset NEC in the < or = 1,500 g group probably relates to a variety of pathogenetic factors.

  13. Docosahexaenoic Acid Rescues Synaptogenesis Impairment and Long-Term Memory Deficits Caused by Postnatal Multiple Sevoflurane Exposures.

    PubMed

    Tao, Guorong; Luo, Yan; Xue, Qingsheng; Li, Guohui; Tan, Yongchang; Xiao, Jinglei; Yu, Buwei

    2016-01-01

    Sevoflurane exposures were demonstrated to induce neurotoxicity in the developing brain in both human and animal studies. However, there is no effective approach to reverse it. The present study aimed to evaluate the feasibility of utilizing docosahexaenoic acid (DHA) to prevent sevoflurane-induced neurotoxicity. P6 (postnatal 6 days) mice were administrated DHA after exposure to 3% sevoflurane for two hours daily in three consecutive days. Molecular expressions of synaptic makers (PSD95, synaptophysin) and synaptic morphological changes were investigated by Western blot analysis and transmission electron microscopy, respectively. Meanwhile, Morris water maze test was used to assess spatial memory of mice at P31 (postnatal 31 days). DHA restored sevoflurane-induced decreased level of PSD95 and synaptophysin expressions and increased PSD areas and also improved long-term spatial memory. These results suggest that DHA could rescue synaptogenesis impairment and long-term memory deficits in postnatal caused by multiple sevoflurane exposures. PMID:27597963

  14. Docosahexaenoic Acid Rescues Synaptogenesis Impairment and Long-Term Memory Deficits Caused by Postnatal Multiple Sevoflurane Exposures

    PubMed Central

    Tao, Guorong; Luo, Yan; Xue, Qingsheng; Li, Guohui; Tan, Yongchang

    2016-01-01

    Sevoflurane exposures were demonstrated to induce neurotoxicity in the developing brain in both human and animal studies. However, there is no effective approach to reverse it. The present study aimed to evaluate the feasibility of utilizing docosahexaenoic acid (DHA) to prevent sevoflurane-induced neurotoxicity. P6 (postnatal 6 days) mice were administrated DHA after exposure to 3% sevoflurane for two hours daily in three consecutive days. Molecular expressions of synaptic makers (PSD95, synaptophysin) and synaptic morphological changes were investigated by Western blot analysis and transmission electron microscopy, respectively. Meanwhile, Morris water maze test was used to assess spatial memory of mice at P31 (postnatal 31 days). DHA restored sevoflurane-induced decreased level of PSD95 and synaptophysin expressions and increased PSD areas and also improved long-term spatial memory. These results suggest that DHA could rescue synaptogenesis impairment and long-term memory deficits in postnatal caused by multiple sevoflurane exposures. PMID:27597963

  15. Docosahexaenoic Acid Rescues Synaptogenesis Impairment and Long-Term Memory Deficits Caused by Postnatal Multiple Sevoflurane Exposures

    PubMed Central

    Tao, Guorong; Luo, Yan; Xue, Qingsheng; Li, Guohui; Tan, Yongchang

    2016-01-01

    Sevoflurane exposures were demonstrated to induce neurotoxicity in the developing brain in both human and animal studies. However, there is no effective approach to reverse it. The present study aimed to evaluate the feasibility of utilizing docosahexaenoic acid (DHA) to prevent sevoflurane-induced neurotoxicity. P6 (postnatal 6 days) mice were administrated DHA after exposure to 3% sevoflurane for two hours daily in three consecutive days. Molecular expressions of synaptic makers (PSD95, synaptophysin) and synaptic morphological changes were investigated by Western blot analysis and transmission electron microscopy, respectively. Meanwhile, Morris water maze test was used to assess spatial memory of mice at P31 (postnatal 31 days). DHA restored sevoflurane-induced decreased level of PSD95 and synaptophysin expressions and increased PSD areas and also improved long-term spatial memory. These results suggest that DHA could rescue synaptogenesis impairment and long-term memory deficits in postnatal caused by multiple sevoflurane exposures.

  16. Effects of Light Curing Method and Exposure Time on Mechanical Properties of Resin Based Dental Materials

    PubMed Central

    Alpöz, A. Riza; Ertuḡrul, Fahinur; Cogulu, Dilsah; Ak, Asli Topaloḡlu; Tanoḡlu, Metin; Kaya, Elçin

    2008-01-01

    Objectives The aim of this study was to investigate microhardness and compressive strength of composite resin (Tetric-Ceram, Ivoclar Vivadent), compomer (Compoglass, Ivoclar, Vivadent), and resin modified glass ionomer cement (Fuji II LC, GC Corp) polymerized using halogen light (Optilux 501, Demetron, Kerr) and LED (Bluephase C5, Ivoclar Vivadent) for different curing times. Methods Samples were placed in disc shaped plastic molds with uniform size of 5 mm diameter and 2 mm in thickness for surface microhardness test and placed in a diameter of 4 mm and a length of 2 mm teflon cylinders for compressive strength test. For each subgroup, 20 samples for microhardness (n=180) and 5 samples for compressive strength were prepared (n=45). In group 1, samples were polymerized using halogen light source for 40 seconds; in group 2 and 3 samples were polymerized using LED light source for 20 seconds and 40 seconds respectively. All data were analyzed by two way analysis of ANOVA and Tukey’s post-hoc tests. Results Same exposure time of 40 seconds with a low intensity LED was found similar or more efficient than a high intensity halogen light unit (P>.05), however application of LED for 20 seconds was found less efficient than 40 seconds curing time (P=.03). Conclusions It is important to increase the light curing time and use appropriate light curing devices to polymerize resin composite in deep cavities to maximize the hardness and compressive strength of restorative materials. PMID:19212507

  17. Reconciling Scratch Space Consumption, Exposure, and Volatility to Achieve Timely Staging of Job Input Data

    SciTech Connect

    Monti, Henri; Butt, Ali R; Vazhkudai, Sudharshan S

    2010-04-01

    Innovative scientific applications and emerging dense data sources are creating a data deluge for high-end computing systems. Processing such large input data typically involves copying (or staging) onto the supercomputer's specialized high-speed storage, scratch space, for sustained high I/O throughput. The current practice of conservatively staging data as early as possible makes the data vulnerable to storage failures, which may entail re-staging and consequently reduced job throughput. To address this, we present a timely staging framework that uses a combination of job startup time predictions, user-specified intermediate nodes, and decentralized data delivery to coincide input data staging with job start-up. By delaying staging to when it is necessary, the exposure to failures and its effects can be reduced. Evaluation using both PlanetLab and simulations based on three years of Jaguar (No. 1 in Top500) job logs show as much as 85.9% reduction in staging times compared to direct transfers, 75.2% reduction in wait time on scratch, and 2.4% reduction in usage/hour.

  18. Gestational exposure to methylmercury and n-3 fatty acids: effects on high- and low-rate operant behavior in adulthood.

    PubMed

    Paletz, Elliott M; Craig-Schmidt, Margaret C; Newland, M Christopher

    2006-01-01

    Fish in the diet is the major source of methylmercury (MeHg) exposure, but eating fish also provides important nutrients. Many fish species contain essential long chain polyunsaturated fatty acids, especially docosahexaenoic acid (DHA), an omega-3 (or n-3) fatty acid, that is important for neural development and function. To examine interactions between MeHg and n-3 fatty acids, female Long-Evans rats were exposed, in utero, to 0, 0.5, or 5 ppm MeHg via drinking water, approximating exposures of 0, 40, and 400 mug/kg/day. They also received pre- and postnatal exposure to a diet containing either fish oil or coconut oil, creating a 2 (Diet)x3 (MeHg) full factorial design, with 6-8 rats per cell. The diets were high or marginal, respectively, in n-3 fatty acids but approximately equal in n-6 fatty acids. No exposure-related effects on developmental milestones or growth were noted. Behavior was evaluated using a series of rapidly increasing fixed ratio (FR) schedules of sucrose reinforcement; 1, 5, 25 and 75 lever presses were required for sucrose delivery, with three sessions provided at each requirement. This phase was followed by four sessions of a differential-reinforcement-of-low-rate-behavior (DRL) schedule, in which presses preceded by 10 s (or more) without a press were reinforced. Subsequently, several progressive ratio (PR) schedules that increased response requirements throughout a single session by a rate of 5%, 10%, or 20% were imposed. Rats exposed during gestation to MeHg had significantly higher response rates than controls under the large FR schedules, during the first session of DRL, and the PR 5% schedule, but neither fish oil nor coconut oil modified MeHg's effects. This finding is consistent with hypotheses that developmental MeHg exposure produced perseverative responding or altered the sensitivity of behavior to its reinforcing consequences and that certain reinforcement contingencies can unmask MeHg's effects.

  19. Ear swelling test by using laser speckle imaging with a long exposure time.

    PubMed

    Kalchenko, Vyacheslav; Kuznetsov, Yuri; Preise, Dina; Meglinski, Igor; Harmelin, Alon

    2014-06-01

    Laser speckle imaging with long exposure time has been applied noninvasively to visualize the immediate reaction of cutaneous vessels in mice in response to a known primary irritant and potential allergen—methyl salicylate. The compound has been used topically on the surface of the pinna and the reaction of the vascular network was examined. We demonstrate that irritant-induced acute vascular reaction can be effectively and accurately detected by laser speckle imaging technique. The current approach holds a great promise for application in routine screening of the cutaneous vascular response induced by contact agents, screenings of mouse ear swelling test, and testing the allergenic potential of new synthetic materials and healthcare pharmaceutical products.

  20. Ear swelling test by using laser speckle imaging with a long exposure time

    NASA Astrophysics Data System (ADS)

    Kalchenko, Vyacheslav; Kuznetsov, Yuri; Preise, Dina; Meglinski, Igor; Harmelin, Alon

    2014-06-01

    Laser speckle imaging with long exposure time has been applied noninvasively to visualize the immediate reaction of cutaneous vessels in mice in response to a known primary irritant and potential allergen-methyl salicylate. The compound has been used topically on the surface of the pinna and the reaction of the vascular network was examined. We demonstrate that irritant-induced acute vascular reaction can be effectively and accurately detected by laser speckle imaging technique. The current approach holds a great promise for application in routine screening of the cutaneous vascular response induced by contact agents, screenings of mouse ear swelling test, and testing the allergenic potential of new synthetic materials and healthcare pharmaceutical products.

  1. Exposure to Perfluorononanoic acid during pregnancy: Evaluations of rat and mice model

    EPA Science Inventory

    Perfluorononanoic acid (PFNA) is a persistent environmental contaminant. Although its levels in the environment are lower than those of perfluorooctane sulfonate (PFOS) or perfluorooctanoic acid (PFOA), its presence in humans is rising and is of concern. Previous studies have in...

  2. Effects of Perfluorinated Phosphonic Acid Exposure during pregnancy in the mouse

    EPA Science Inventory

    Perfluorinated phosphonic acids (PFPAs) are a member of the perfluoroalkyl acid (PFAA) family, and are structurally similar to the perfluoroalkyl sulfonates and perfluoroalkyl carboxylates. These chemicals have recently been detected in the environment, particularly in surface wa...

  3. An Evaluation of Gestational Exposure to Perfluorooctanoic Acid (PFOA): Effects on Body Composition and Physiological Factors

    EPA Science Inventory

    Exposure to environmental pollutants can be a factor for induction of metabolic disorders. This study examined if exposure to PFOA during development could alter body composition and other physiological outcomes. Study 1: Pregnant CD-1 mice were gavaged with PFOA at 0,0.001,0.01,...

  4. GPS-based Microenvironment Tracker (MicroTrac) Model to Estimate Time-Location of Individuals for Air Pollution Exposure Assessments: Model Evaluation in Central North Carolina

    EPA Science Inventory

    A critical aspect of air pollution exposure assessment is the estimation of the time spent by individuals in various microenvironments (ME). Accounting for the time spent in different ME with different pollutant concentrations can reduce exposure misclassifications, while failure...

  5. Analysis of health effects resulting from population exposures to acid precipitation precursors.

    PubMed Central

    Ozkaynak, H; Spengler, J D

    1985-01-01

    Types of available studies relevant to the quantification of air pollution health effects and their principal limitations are discussed. Assessments are provided based on review and re-analysis of previously reported data bases, synthesis of published findings, and original analysis of health data sets using new methods or recent size-specific particle mass measurements. Interim results from ongoing research activities on airborne particle health effects are presented. It is shown that preliminary results obtained from cross-sectional and time-series mortality studies appear to be consistent, indicating that particulate air pollution, even at current levels, could be of concern for public health. Throughout the paper, methodological deficiencies and remaining gaps in knowledge are identified. In particular, uncertainties associated with the reported exposure-response coefficients are assessed. Finally, by characterizing the limitations of analysis we propose various recommendations for future studies and research that will serve to further define the nature, magnitude, and uncertainties of air pollution health risks. PMID:4076093

  6. Embryological exposure to valproic acid induces social interaction deficits in zebrafish (Danio rerio): A developmental behavior analysis.

    PubMed

    Zimmermann, Fernanda Francine; Gaspary, Karina Vidarte; Leite, Carlos Eduardo; De Paula Cognato, Giana; Bonan, Carla Denise

    2015-01-01

    Changes in social behavior are associated with brain disorders, including mood disorders, stress, schizophrenia, Alzheimer's disease, and autism spectrum disorders (ASD). Autism is a complex neurodevelopmental disorder characterized by deficits in social interaction, impaired communication, anxiety, hyperactivity, and the presence of restricted interests. Zebrafish is one of the most social vertebrates used as a model in biomedical research, contributing to an understanding of the mechanisms that underlie social behavior. Valproic acid (VPA) is used as an anti-epileptic drug and mood stabilizer; however, prenatal VPA exposure in humans has been associated with an increased incidence of autism and it can also affect fetal brain development. Therefore, we conducted a behavioral screening at different periods of zebrafish development at 6, 30, 70, and 120dpf (days postfertilization) after VPA exposure in the early development stage to investigate social behavior, locomotion, aggression, and anxiety. VPA (48μM) exposure during the first 48hpf (hours postfertilization) did not promote changes on survival, morphology, and hatching rate at 24hpf, 48hpf, and 72hpf. The behavioral patterns suggest that VPA exposure induces changes in locomotor activity and anxiety at different developmental periods in zebrafish. Furthermore, a social interaction deficit is present at 70dpf and 120dpf. VPA exposure did not affect aggression in the adult stage at 70dpf and 120dpf. This is the first study that demonstrated zebrafish exposed to VPA during the first 48h of development exhibit deficits in social interaction, anxiety, and hyperactivity at different developmental periods.

  7. Acute exposure to realistic acid fog: Effects on respiratory function and airway responsiveness in asthmatics

    SciTech Connect

    Leduc, D.; De Vuyst, P.; Yernault, J.C.

    1995-11-01

    The biological effects of acid fog composed primarily of ammonium ions and sulfate are described. Subjects with asthma were exposed for one hour to sulfuric acid aerosol. Significant changes were not observed. Other asthma subjects were exposed to acid fog containing sulfate and ammonium ions. Again, pulmonary and bronchial function were not modified after inhalation.

  8. Real-time emission factor measurements of isocyanic acid from light duty gasoline vehicles.

    PubMed

    Brady, James M; Crisp, Timia A; Collier, Sonya; Kuwayama, Toshihiro; Forestieri, Sara D; Perraud, Véronique; Zhang, Qi; Kleeman, Michael J; Cappa, Christopher D; Bertram, Timothy H

    2014-10-01

    Exposure to gas-phase isocyanic acid (HNCO) has been previously shown to be associated with the development of atherosclerosis, cataracts and rheumatoid arthritis. As such, accurate emission inventories for HNCO are critical for modeling the spatial and temporal distribution of HNCO on a regional and global scale. To date, HNCO emission rates from light duty gasoline vehicles, operated under driving conditions, have not been determined. Here, we present the first measurements of real-time emission factors of isocyanic acid from a fleet of eight light duty gasoline-powered vehicles (LDGVs) tested on a chassis dynamometer using the Unified Driving Cycle (UC) at the California Air Resources Board (CARB) Haagen-Smit test facility, all of which were equipped with three-way catalytic converters. HNCO emissions were observed from all vehicles, in contrast to the idealized laboratory measurements. We report the tested fleet averaged HNCO emission factors, which depend strongly on the phase of the drive cycle; ranging from 0.46 ± 0.13 mg kg fuel(-1) during engine start to 1.70 ± 1.77 mg kg fuel(-1) during hard acceleration after the engine and catalytic converter were warm. The tested eight-car fleet average fuel based HNCO emission factor was 0.91 ± 0.58 mg kg fuel(-1), within the range previously estimated for light duty diesel-powered vehicles (0.21-3.96 mg kg fuel(-1)). Our results suggest that HNCO emissions from LDGVs represent a significant emission source in urban areas that should be accounted for in global and regional models. PMID:25198906

  9. Real-time emission factor measurements of isocyanic acid from light duty gasoline vehicles.

    PubMed

    Brady, James M; Crisp, Timia A; Collier, Sonya; Kuwayama, Toshihiro; Forestieri, Sara D; Perraud, Véronique; Zhang, Qi; Kleeman, Michael J; Cappa, Christopher D; Bertram, Timothy H

    2014-10-01

    Exposure to gas-phase isocyanic acid (HNCO) has been previously shown to be associated with the development of atherosclerosis, cataracts and rheumatoid arthritis. As such, accurate emission inventories for HNCO are critical for modeling the spatial and temporal distribution of HNCO on a regional and global scale. To date, HNCO emission rates from light duty gasoline vehicles, operated under driving conditions, have not been determined. Here, we present the first measurements of real-time emission factors of isocyanic acid from a fleet of eight light duty gasoline-powered vehicles (LDGVs) tested on a chassis dynamometer using the Unified Driving Cycle (UC) at the California Air Resources Board (CARB) Haagen-Smit test facility, all of which were equipped with three-way catalytic converters. HNCO emissions were observed from all vehicles, in contrast to the idealized laboratory measurements. We report the tested fleet averaged HNCO emission factors, which depend strongly on the phase of the drive cycle; ranging from 0.46 ± 0.13 mg kg fuel(-1) during engine start to 1.70 ± 1.77 mg kg fuel(-1) during hard acceleration after the engine and catalytic converter were warm. The tested eight-car fleet average fuel based HNCO emission factor was 0.91 ± 0.58 mg kg fuel(-1), within the range previously estimated for light duty diesel-powered vehicles (0.21-3.96 mg kg fuel(-1)). Our results suggest that HNCO emissions from LDGVs represent a significant emission source in urban areas that should be accounted for in global and regional models.

  10. Dietary exposure of Hong Kong adults to fatty acid esters of 3-monochloropropane-1,2-diol.

    PubMed

    Chung, H Y; Chung, Stephen W C; Chan, B T P; Ho, Yuk Yin; Xiao, Ying

    2013-01-01

    A total of 290 individual food samples were collected in Hong Kong, China, for 3-monochloropropane-1,2-diol (3-MCPD) fatty acid esters analysis. Most samples were processed food and in ready-to-eat form. The results show that the levels of 3-MCPD fatty acid esters were high in biscuits, fats and oils, snacks and Chinese pastry with mean bound 3-MCPD levels of 440, 390, 270 and 270 μg kg⁻¹, respectively. The dietary exposures to bound 3-MCPD of average and high adult consumers were estimated to be 0.20 and 0.53 μg kg bw⁻¹ day⁻¹, respectively. The primary toxicological concern of 3-MCPD fatty acid esters is its potential to release 3-MCPD in vivo during digestion in the gastrointestinal tract. 3-MCPD would affect the kidney, the central nervous system and the male reproductive system of rats. Assuming that 100% of the 3-MCPD was released from 3-MCPD fatty acid esters by hydrolysis in the digestive system, the dietary exposures to 3-MCPD for average and high adult consumers were only 10% and 26% of the provisional maximum tolerable daily intake (PMTDI) of 3-MCPD established by the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives (JECFA) (2 μg kg bw⁻¹ day⁻¹), respectively. The results suggest that both average and high adult consumers are unlikely to experience major toxicological effects of 3-MCPD.

  11. Time-dependent Changes of Cadmium and Metallothionein after Short-term Exposure to Cadmium in Rats

    PubMed Central

    Cho, Mi Ran; Jeong, Sang-Hee; Cho, Myung Haing

    2010-01-01

    The time-dependent changes in cadmium (Cd) concentration were studied in Female Sprague-Dawley (SD) rats during and after Cd exposure via drinking water (10 and 50 ppm) for 30 days. The cadmium concentration in muscle, liver, kidney, blood plasma, and urine, and the metallothionein concentration in blood plasma were determined every 10 days during exposure and every 7 days after exposure for 3 weeks. The muscle Cd concentration did not change during, and neither after, exposure. The liver Cd concentration increased from 1.4 to 3.3 (at 10 ppm) and from 6.1 to 10.1 folds (at 50 ppm) during exposure and remained higher than those of controls in both groups even during post-exposure period. The kidney Cd concentrations were 2.3 to 5.1 (at 10 ppm) and 4.9-14.0 folds (at 50 ppm) higher than those of controls during exposure and also remained elevated during the post-exposure period. Plasma Cd concentrations were not significantly different from those of controls in both groups. Urine Cd concentrations were more than 2 folds (at 10 ppm) and 6.5 to 12.6 folds (at 50 ppm) higher than those of controls but rapidly decreased over the 7 days of withdrawal. Blood plasma metallothionein concentrations were more than 2.4 folds (at 10 ppm) and 3.1 to 7.4 folds (at 50 ppm) , and they remained elevated till 7 days (10 ppm) and 14 days (at 50 ppm) after exposure. Our data support that Cd in urine could be a useful biomarker during Cd exposure period and metallothionein in blood plasma could be as a supportive biological marker for during and post Cd exposure. PMID:24278516

  12. Comparison of nested case-control and survival analysis methodologies for analysis of time-dependent exposure

    PubMed Central

    Essebag, Vidal; Platt, Robert W; Abrahamowicz, Michal; Pilote, Louise

    2005-01-01

    Background Epidemiological studies of exposures that vary with time require an additional level of methodological complexity to account for the time-dependence of exposure. This study compares a nested case-control approach for the study of time-dependent exposure with cohort analysis using Cox regression including time-dependent covariates. Methods A cohort of 1340 subjects with four fixed and seven time-dependent covariates was used for this study. Nested case-control analyses were repeated 100 times for each of 4, 8, 16, 32, and 64 controls per case, and point estimates were compared to those obtained using Cox regression on the full cohort. Computational efficiencies were evaluated by comparing central processing unit times required for analysis of the cohort at sizes 1, 2, 4, 8, 16, and 32 times its initial size. Results Nested case-control analyses yielded results that were similar to results of Cox regression on the full cohort. Cox regression was found to be 125 times slower than the nested case-control approach (using four controls per case). Conclusions The nested case-control approach is a useful alternative for cohort analysis when studying time-dependent exposures. Its superior computational efficiency may be particularly useful when studying rare outcomes in databases, where the ability to analyze larger sample sizes can improve the power of the study. PMID:15670334

  13. Behavioral changes during exposure to 1,1,1-trichloroethane: time-course and relationship to blood solvent levels.

    PubMed

    Mackay, C J; Campbell, L; Samuel, A M; Alderman, K J; Idzikowski, C; Wilson, H K; Gompertz, D

    1987-01-01

    We report the results of an exposure chamber study in which volunteers were exposed to 0, 950 mg.m-3 (175 ppm) and 1,990 mg.m-3 (350 ppm) of 1,1,1-trichloroethane for 3.5 hours. The time-course of the behavioral changes and the relationship to blood concentrations of 1,1,1-trichloroethane were investigated. A pattern of performance deficits consistent with earlier work was found for some of the tests of psychomotor performance. The time-course of these appeared to be rapid, occurring in some cases within 20 minutes of exposure. For those tasks shown to be sensitive to 1,1,1-trichloroethane exposure, the development of performance changes followed the time-course of blood solvent levels. Two behavioral tests not previously used in this type of work were also employed. One was concerned with the distractability of attention and concentration (the Stroop test), and the other was concerned with analysing grammatical statements (the syntactic reasoning test). Different effects were found. In the Stroop test, enhanced performance was observed following exposure; however, the syntactic reasoning test was found to be resistant to solvent effects. Measures of short-term subjective well-being were not affected by exposure. It is suggested that the observations of time-course effects in performance and their relationship to change in blood solvent levels have implications for psychological test selection and for study designs for examining field exposure.

  14. Time- and state-dependent effects of methanethiosulfonate ethylammonium (MTSEA) exposure differ between heart and skeletal muscle voltage-gated Na(+) channels.

    PubMed

    O'Reilly, John P; Shockett, Penny E

    2012-03-01

    The substituted-cysteine scanning method (SCAM) is used to study conformational changes in proteins. Experiments using SCAM involve site-directed mutagenesis to replace native amino acids with cysteine and subsequent exposure to a methanethiosulfonate (MTS) reagent such as methanethiosulfonate ethylammonium (MTSEA). These reagents react with substituted-cysteines and can provide functional information about relative positions of amino acids within a protein. In the human heart voltage-gated Na(+) channel hNav1.5 there is a native cysteine at position C373 that reacts rapidly with MTS reagents resulting in a large reduction in whole-cell Na(+) current (I(Na)). Therefore, in order to use SCAM in studies in this isoform, this native cysteine is mutated to a non-reactive residue, e.g., tyrosine. This mutant, hNav1.5-C373Y, is resistant to the MTS-mediated decrease in I(Na). Here we show that this resistance is time- and state-dependent. With relatively short exposure times to MTSEA (<4min), there is little effect on I(Na). However, with longer exposures (4-8min), there is a large decrease in I(Na), but this effect is only found when hNav1.5-C373Y is inactivated (fast or slow) - MTSEA has little effect in the closed state. Additionally, this long-term, state-dependent effect is not seen in human skeletal muscle Na(+) channel isoform hNav1.4, which has a native tyrosine at the homologous site C407. We conclude that differences in molecular determinants of inactivation between hNav1.4 and hNav1.5 underlie the difference in response to MTSEA exposure.

  15. Estimating the time interval between exposure to the World Trade Center disaster and incident diagnoses of obstructive airway disease.

    PubMed

    Glaser, Michelle S; Webber, Mayris P; Zeig-Owens, Rachel; Weakley, Jessica; Liu, Xiaoxue; Ye, Fen; Cohen, Hillel W; Aldrich, Thomas K; Kelly, Kerry J; Nolan, Anna; Weiden, Michael D; Prezant, David J; Hall, Charles B

    2014-08-01

    Respiratory disorders are associated with occupational and environmental exposures. The latency period between exposure and disease onset remains uncertain. The World Trade Center (WTC) disaster presents a unique opportunity to describe the latency period for obstructive airway disease (OAD) diagnoses. This prospective cohort study of New York City firefighters compared the timing and incidence of physician-diagnosed OAD relative to WTC exposure. Exposure was categorized by WTC arrival time as high (on the morning of September 11, 2001), moderate (after noon on September 11, 2001, or on September 12, 2001), or low (during September 13-24, 2001). We modeled relative rates and 95% confidence intervals of OAD incidence by exposure over the first 5 years after September 11, 2001, estimating the times of change in the relative rate with change point models. We observed a change point at 15 months after September 11, 2001. Before 15 months, the relative rate for the high- versus low-exposure group was 3.96 (95% confidence interval: 2.51, 6.26) and thereafter, it was 1.76 (95% confidence interval: 1.26, 2.46). Incident OAD was associated with WTC exposure for at least 5 years after September 11, 2001. There were higher rates of new-onset OAD among the high-exposure group during the first 15 months and, to a lesser extent, throughout follow-up. This difference in relative rate by exposure occurred despite full and free access to health care for all WTC-exposed firefighters, demonstrating the persistence of WTC-associated OAD risk. PMID:24980522

  16. Vitamin C, uric acid, and glutathione gradients in murine stratum corneum and their susceptibility to ozone exposure.

    PubMed

    Weber, S U; Thiele, J J; Cross, C E; Packer, L

    1999-12-01

    The stratum corneum has been recognized as the main cutaneous oxidation target of atmospheric ozone (O3), a major part of photochemical smog. This study reports the presence and distribution of vitamin C, glutathione, and uric acid in murine stratum corneum, and evaluates their susceptibility to acute environmental exposure to O3. Based on tape stripping and a modified extraction method with high performance liquid chromatography electrochemical analysis, we detected vitamin C (208.0 +/- 82.5 pmol per 10 consecutive pooled tapes), glutathione (283.7 +/-96.3), and uric acid (286.4 +/-47.1) in murine stratum corneum as compared with only 16.5 +/- 1.4 pmol alpha-tocopherol. Vitamin C, glutathione (both p < 00.001), and urate (p < 0.01) were found to exhibit a gradient with the lowest concentrations in the outer layers and a steep increase in the deeper layers. To investigate the effect of O3 exposure on hydrophilic antioxidants, we exposed SKH-1 hairless mice to O3 concentrations of 0, 0.8, 1, and 10 p.p.m., and stratum corneum was analyzed before and after exposure. Whereas mock exposure with 0 p.p. m. for 2 h had no significant effect, O3 doses of 1 p.p.m. for 2 h and above showed depletion of all three antioxidants. Vitamin C was decreased to 80% +/- 15% of its pretreatment content (p < 0.05), GSH to 41% +/- 24% (p < 0.01), and uric acid to 44% +/- 28% (p < 0.01). This report demonstrates the previously unrecognized role of hydrophilic antioxidants in the stratum corneum and provides further evidence that O3 induces oxidative stress in this outer skin layer.

  17. Loss of growth inhibitory effects of retinoic acid in human breast cancer cells following long-term exposure to retinoic acid

    PubMed Central

    Stephen, R; Darbre, P D

    2000-01-01

    Although retinoids are known to be inhibitory to breast cancer cell growth, a key remaining question is whether they would remain effective if administered long-term. We describe here the long-term effects of all-trans retinoic acid on two oestrogen-dependent human breast cancer cell lines MCF7 and ZR-75-1. Although both cell lines were growth inhibited by retinoic acid in the short-term in either the absence or the presence of oestradiol, prolonged culture with 1 μM all-trans retinoic acid resulted in the cells acquiring resistance to the growth inhibitory effects of retinoic acid. Time courses showed that oestrogen deprivation of the cell lines resulted in upregulation of the basal non-oestrogen stimulated growth rate such that cells learned to grow at the same rate without as with oestradiol, but the cells remained growth inhibited by retinoic acid throughout. Addition of 1 μM all-trans retinoic acid to steroid deprivation conditions resulted in reproducible loss of growth response to both retinoic acid and oestradiol, although the time courses were separable in that loss of growth response to retinoic acid preceded that of oestradiol. Loss of growth response to retinoic acid did not involve loss of receptors, ER as measured by steroid binding assay or RARα as measured by Northern blotting. Function of the receptors was retained in terms of the ability of both oestradiol and retinoic acid to upregulate pS2 gene expression, but there was reduced ability to upregulate transiently transfected ERE- and RRE-linked reporter genes. Despite the accepted role of IGFBP3 in retinoic acid-mediated growth inhibition, progression to retinoic acid resistance occurred irrespective of level of IGFBP3, which remained high in the resistant MCF7 cells. Measurement of AP1 activity showed that the two cell lines had markedly different basal AP1 activities, but that progression to resistance was accompanied in both cases by a lost ability of retinoic acid to reduce AP1 activity

  18. Anacardic Acids from Cashew Nuts Ameliorate Lung Damage Induced by Exposure to Diesel Exhaust Particles in Mice

    PubMed Central

    Carvalho, Ana Laura Nicoletti; Annoni, Raquel; Torres, Larissa Helena Lobo; Durão, Ana Carolina Cardoso Santos; Shimada, Ana Lucia Borges; Almeida, Francine Maria; Hebeda, Cristina Bichels; Lopes, Fernanda Degobbi Tenorio Quirino Santos; Dolhnikoff, Marisa; Martins, Milton Arruda; Silva, Luiz Fernando Ferraz; Farsky, Sandra Helena Poliselli; Saldiva, Paulo Hilário Nascimento; Ulrich, Cornelia M.; Owen, Robert W.; Marcourakis, Tania; Trevisan, Maria Teresa Salles; Mauad, Thais

    2013-01-01

    Anacardic acids from cashew nut shell liquid, a Brazilian natural substance, have antimicrobial and antioxidant activities and modulate immune responses and angiogenesis. As inflammatory lung diseases have been correlated to environmental pollutants exposure and no reports addressing the effects of dietary supplementation with anacardic acids on lung inflammation in vivo have been evidenced, we investigated the effects of supplementation with anacardic acids in a model of diesel exhaust particle- (DEP-) induced lung inflammation. BALB/c mice received an intranasal instillation of 50 μg of DEP for 20 days. Ten days prior to DEP instillation, animals were pretreated orally with 50, 150, or 250 mg/kg of anacardic acids or vehicle (100 μL of cashew nut oil) for 30 days. The biomarkers of inflammatory and antioxidant responses in the alveolar parenchyma, bronchoalveolar lavage fluid (BALF), and pulmonary vessels were investigated. All doses of anacardic acids ameliorated antioxidant enzyme activities and decreased vascular adhesion molecule in vessels. Animals that received 50 mg/kg of anacardic acids showed decreased levels of neutrophils and tumor necrosis factor in the lungs and BALF, respectively. In summary, we demonstrated that AAs supplementation has a potential protective role on oxidative and inflammatory mechanisms in the lungs. PMID:23533495

  19. Anacardic acids from cashew nuts ameliorate lung damage induced by exposure to diesel exhaust particles in mice.

    PubMed

    Carvalho, Ana Laura Nicoletti; Annoni, Raquel; Torres, Larissa Helena Lobo; Durão, Ana Carolina Cardoso Santos; Shimada, Ana Lucia Borges; Almeida, Francine Maria; Hebeda, Cristina Bichels; Lopes, Fernanda Degobbi Tenorio Quirino Santos; Dolhnikoff, Marisa; Martins, Milton Arruda; Silva, Luiz Fernando Ferraz; Farsky, Sandra Helena Poliselli; Saldiva, Paulo Hilário Nascimento; Ulrich, Cornelia M; Owen, Robert W; Marcourakis, Tania; Trevisan, Maria Teresa Salles; Mauad, Thais

    2013-01-01

    Anacardic acids from cashew nut shell liquid, a Brazilian natural substance, have antimicrobial and antioxidant activities and modulate immune responses and angiogenesis. As inflammatory lung diseases have been correlated to environmental pollutants exposure and no reports addressing the effects of dietary supplementation with anacardic acids on lung inflammation in vivo have been evidenced, we investigated the effects of supplementation with anacardic acids in a model of diesel exhaust particle- (DEP-) induced lung inflammation. BALB/c mice received an intranasal instillation of 50  μ g of DEP for 20 days. Ten days prior to DEP instillation, animals were pretreated orally with 50, 150, or 250 mg/kg of anacardic acids or vehicle (100  μ L of cashew nut oil) for 30 days. The biomarkers of inflammatory and antioxidant responses in the alveolar parenchyma, bronchoalveolar lavage fluid (BALF), and pulmonary vessels were investigated. All doses of anacardic acids ameliorated antioxidant enzyme activities and decreased vascular adhesion molecule in vessels. Animals that received 50 mg/kg of anacardic acids showed decreased levels of neutrophils and tumor necrosis factor in the lungs and BALF, respectively. In summary, we demonstrated that AAs supplementation has a potential protective role on oxidative and inflammatory mechanisms in the lungs.

  20. Effect of oxidant concentration, exposure time, and seed particles on secondary organic aerosol chemical composition and yield

    DOE PAGES

    Lambe, A. T.; Chhabra, P. S.; Onasch, T. B.; Brune, W. H.; Hunter, J. F.; Kroll, J. H.; Cummings, M. J.; Brogan, J. F.; Parmar, Y.; Worsnop, D. R.; et al

    2015-03-18

    We performed a systematic intercomparison study of the chemistry and yields of secondary organic aerosol (SOA) generated from OH oxidation of a common set of gas-phase precursors in a Potential Aerosol Mass (PAM) continuous flow reactor and several environmental chambers. In the flow reactor, SOA precursors were oxidized using OH concentrations ranging from 2.0 × 108 to 2.2 × 1010 molec cm-3 over exposure times of 100 s. In the environmental chambers, precursors were oxidized using OH concentrations ranging from 2 × 106 to 2 × 107 molec cm-3 over exposure times of several hours. The OH concentration in themore » chamber experiments is close to that found in the atmosphere, but the integrated OH exposure in the flow reactor can simulate atmospheric exposure times of multiple days compared to chamber exposure times of only a day or so. In most cases, for a specific SOA type the most-oxidized chamber SOA and the least-oxidized flow reactor SOA have similar mass spectra, oxygen-to-carbon and hydrogen-to-carbon ratios, and carbon oxidation states at integrated OH exposures between approximately 1 × 1011 and 2 × 1011 molec cm-3 s, or about 1–2 days of equivalent atmospheric oxidation. This observation suggests that in the range of available OH exposure overlap for the flow reactor and chambers, SOA elemental composition as measured by an aerosol mass spectrometer is similar whether the precursor is exposed to low OH concentrations over long exposure times or high OH concentrations over short exposure times. This similarity in turn suggests that both in the flow reactor and in chambers, SOA chemical composition at low OH exposure is governed primarily by gas-phase OH oxidation of the precursors rather than heterogeneous oxidation of the condensed particles. In general, SOA yields measured in the flow reactor are lower than measured in chambers for the range of equivalent OH exposures that can be measured in both the flow reactor and chambers. The influence of

  1. Free fatty acid receptor 1 (FFAR1/GPR40) signaling affects insulin secretion by enhancing mitochondrial respiration during palmitate exposure.

    PubMed

    Kristinsson, Hjalti; Bergsten, Peter; Sargsyan, Ernest

    2015-12-01

    Fatty acids affect insulin secretion via metabolism and FFAR1-mediated signaling. Recent reports indicate that these two pathways act synergistically. Still it remains unclear how they interrelate. Taking into account the key role of mitochondria in insulin secretion, we attempted to dissect the metabolic and FFAR1-mediated effects of fatty acids on mitochondrial function. One-hour culture of MIN6 cells with palmitate significantly enhanced mitochondrial respiration. Antagonism or silencing of FFAR1 prevented the palmitate-induced rise in respiration. On the other hand, in the absence of extracellular palmitate FFAR1 agonists caused a modest increase in respiration. Using an agonist of the M3 muscarinic acetylcholine receptor and PKC inhibitor we found that in the presence of the fatty acid mitochondrial respiration is regulated via Gαq protein-coupled receptor signaling. The increase in respiration in palmitate-treated cells was largely due to increased glucose utilization and oxidation. However, glucose utilization was not dependent on FFAR1 signaling. Collectively, these results indicate that mitochondrial respiration in palmitate-treated cells is enhanced via combined action of intracellular metabolism of the fatty acid and the Gαq-coupled FFAR1 signaling. Long-term palmitate exposure reduced ATP-coupling efficiency of mitochondria and deteriorated insulin secretion. The presence of the FFAR1 antagonist during culture did not improve ATP-coupling efficiency, however, it resulted in enhanced mitochondrial respiration and improved insulin secretion after culture. Taken together, our study demonstrates that during palmitate exposure, integrated actions of fatty acid metabolism and fatty acid-induced FFAR1 signaling on mitochondrial respiration underlie the synergistic action of the two pathways on insulin secretion.

  2. Exposure time independent summary statistics for assessment of drug dependent cell line growth inhibition

    PubMed Central

    2014-01-01

    Background In vitro generated dose-response curves of human cancer cell lines are widely used to develop new therapeutics. The curves are summarised by simplified statistics that ignore the conventionally used dose-response curves’ dependency on drug exposure time and growth kinetics. This may lead to suboptimal exploitation of data and biased conclusions on the potential of the drug in question. Therefore we set out to improve the dose-response assessments by eliminating the impact of time dependency. Results First, a mathematical model for drug induced cell growth inhibition was formulated and used to derive novel dose-response curves and improved summary statistics that are independent of time under the proposed model. Next, a statistical analysis workflow for estimating the improved statistics was suggested consisting of 1) nonlinear regression models for estimation of cell counts and doubling times, 2) isotonic regression for modelling the suggested dose-response curves, and 3) resampling based method for assessing variation of the novel summary statistics. We document that conventionally used summary statistics for dose-response experiments depend on time so that fast growing cell lines compared to slowly growing ones are considered overly sensitive. The adequacy of the mathematical model is tested for doxorubicin and found to fit real data to an acceptable degree. Dose-response data from the NCI60 drug screen were used to illustrate the time dependency and demonstrate an adjustment correcting for it. The applicability of the workflow was illustrated by simulation and application on a doxorubicin growth inhibition screen. The simulations show that under the proposed mathematical model the suggested statistical workflow results in unbiased estimates of the time independent summary statistics. Variance estimates of the novel summary statistics are used to conclude that the doxorubicin screen covers a significant diverse range of responses ensuring it is

  3. Constraining the Timing of Neoglaciation: Moraine Exposure Ages from Baffin Island, Arctic Canada

    NASA Astrophysics Data System (ADS)

    Crump, S. E.; Miller, G. H.

    2014-12-01

    A long-term Neoglacial cooling trend, beginning ~6 ka, is well documented across the Arctic and correlates with a monotonic decline in Northern Hemisphere summer insolation. However, paleoclimate proxy records point to decadal- to millennial-scale variability superimposed on overall cooling. This climate variability is reflected in the fluctuations of Arctic glaciers over the course of several millennia. The most recent Neoglacial advance, the Little Ice Age (LIA; ~1275-1850 AD), was generally more extensive than pre-LIA advances and thus destroyed most evidence of previous advances. As such, the timing and extent of earlier Neoglacial advances are not well constrained. However, several extant glaciers on Cumberland Peninsula, Baffin Island, are fronted by nested ice-cored moraine sequences in which multiple pre-LIA moraines are preserved. We have generated absolute ages on moraine sequences for Snow Creek and Throne Glaciers using 10Be in moraine boulders. Nine 10Be ages from the two most distal moraine crests at Snow Creek Glacier range from ~1.8 ka to ~5.7 ka, and twelve ages from the two most distal moraine crests at Throne Glacier range from ~1.1 ka to ~4.6 ka. The wide spread of exposure ages in these settings is likely due to the degradation of moraine ice cores and the disturbance of older moraines by younger readvances. Because these processes result in the exposure of new clasts on the moraine post-emplacement, the oldest ages in these datasets likely provide the best estimates for the earliest Neoglacial advances. These data also indicate that in some settings, early Neoglacial alpine glacier advances reached similar extents as their LIA maxima, possibly due to large ice-cored moraines impeding LIA advances. Glacier modeling efforts and complementary lacustrine sediment records will help to unravel the complex Neoglacial history in this region.

  4. Time Course of Heart Rate Variability Response to PM2.5 Exposure from Secondhand Smoke

    PubMed Central

    Garza, Jennifer L.; Mittleman, Murray A.; Zhang, Jinming; Christiani, David C.; Cavallari, Jennifer M

    2016-01-01

    Purpose: Exposure to secondhand smoke (SHS) has been associated with decreased heart rate variability (HRV). However, the time course of this association is unclear. Therefore, the objective of this study was to investigate the association between 15–240 minute SHS-related fine particulate matter (PM2.5) moving averages and indices of HRV. Methods: With a panel study design, we used personal monitors to continuously measure PM2.5 and HRV of 35 participants who were exposed to SHS for approximately 6 hours. Results: We observed negative, significant associations between 5-minute HRV indices and 15 minute PM2.5 moving averages and 240 minute PM2.5 moving averages: there was a significant (p<0.01) 7.5% decrease in the 5-minute square root of the mean squared differences of successive normal heart beats associated with (RMSSD), and a significant (p<0.01) 14.7% decrease in the 5-minute high frequency (HF) power associated with the 15 minute PM2.5 moving averages; there was also a significant (p<0.01) 46.9% decrease in the 5-minute RMSSD, and a significant (p<0.01) 77.7% decrease in the 5-minute high frequency (HF) power associated with the 240 minute PM2.5 moving averages. Conclusions: Our findings that exposure to SHS related PM2.5 was associated with HRV support the hypothesis that SHS can affect the cardiovascular system. The negative associations reported between short and longer term PM2.5 and HRV indicate adverse effects of SHS on the cardiovascular system. PMID:27223894

  5. Work-Time Exposure and Acute Injuries in Inshore Lobstermen of the Northeast United States.

    PubMed

    Fulmer, Scott; Buchholz, Bryan; Jenkins, Paul; Scribani, Melissa

    2016-01-01

    The objective of this study was to inform efforts to reduce risk for musculoskeletal disorders among commercial lobstermen by characterizing and quantifying injuries that occur to people while harvesting lobsters commercially in the Northeast United States. This study aimed to estimate a denominator of exposure to lobstering in full-time equivalents (FTE), to estimate a fatality rate, and to calculate incidence rates for acute injuries within the sample population. Captains were randomly selected from those licensed to fish in Maine and Massachusetts. Data on work exposure and injuries with rapid onset that occurred on the boat ("acute injuries") were collected using a survey, which was administered quarterly via phone or face-to-face interview with the captain. The quarterly survey assessed the number of weeks worked during the quarter, average crew size, number of trips per week, and average trip length in hours. In addition, this survey captured relevant information (body segment affected, type of injury, and whether treatment was received) on all acute injuries occurring during the quarter. FTE were estimated using fishermen days and fishermen hours. The annual FTE estimated using days was 2,557 and using hours was 2,855. As expected, the summer months (3rd quarter) had the highest FTE and the winter (1st quarter) the lowest FTE. Fall (4th quarter) and spring (2nd quarter) ranked second and third, respectively. The incidence rates for all injuries (49.7/100 FTE) and injuries requiring treatment (15.0/100 FTE) were much higher than those reported in other studies of fishing that used Coast Guard data.

  6. Work-Time Exposure and Acute Injuries in Inshore Lobstermen of the Northeast United States.

    PubMed

    Fulmer, Scott; Buchholz, Bryan; Jenkins, Paul; Scribani, Melissa

    2016-01-01

    The objective of this study was to inform efforts to reduce risk for musculoskeletal disorders among commercial lobstermen by characterizing and quantifying injuries that occur to people while harvesting lobsters commercially in the Northeast United States. This study aimed to estimate a denominator of exposure to lobstering in full-time equivalents (FTE), to estimate a fatality rate, and to calculate incidence rates for acute injuries within the sample population. Captains were randomly selected from those licensed to fish in Maine and Massachusetts. Data on work exposure and injuries with rapid onset that occurred on the boat ("acute injuries") were collected using a survey, which was administered quarterly via phone or face-to-face interview with the captain. The quarterly survey assessed the number of weeks worked during the quarter, average crew size, number of trips per week, and average trip length in hours. In addition, this survey captured relevant information (body segment affected, type of injury, and whether treatment was received) on all acute injuries occurring during the quarter. FTE were estimated using fishermen days and fishermen hours. The annual FTE estimated using days was 2,557 and using hours was 2,855. As expected, the summer months (3rd quarter) had the highest FTE and the winter (1st quarter) the lowest FTE. Fall (4th quarter) and spring (2nd quarter) ranked second and third, respectively. The incidence rates for all injuries (49.7/100 FTE) and injuries requiring treatment (15.0/100 FTE) were much higher than those reported in other studies of fishing that used Coast Guard data. PMID:26788780

  7. Gene Expression Profiles in Zebrafish Brain after Acute Exposure to Domoic Acid at Symptomatic and Asymptomatic Doses

    PubMed Central

    Lefebvre, Kathi A.; Tilton, Susan C.; Bammler, Theo K.; Beyer, Richard P.; Srinouanprachan, Sengkeo; Stapleton, Patricia L.; Farin, Federico M.; Gallagher, Evan P.

    2009-01-01

    Domoic acid (DA) is a neuroexcitatory amino acid that is naturally produced by some marine diatom species of the genus Pseudo-nitzschia. Ingestion of DA-contaminated seafood by humans results in a severe neurotoxic disease known as amnesic shellfish poisoning (ASP). Clinical signs of ASP include seizures and neuronal damage from activation of ionotropic glutamate receptors. However, the impacts of DA exposure at levels below those known to induce outward signs of neurobehavioral exicitotoxicity have not been well characterized. To further understand the mechanisms of neurotoxic injury associated with DA exposure, we examined the transcriptome of whole brains from zebrafish (Danio rerio) receiving intracoelomic (IC) injection of DA at both symptomatic and asymptomatic doses. A majority of zebrafish exposed to high-dose DA (1.2 μg DA/g) exhibited clinical signs of neuroexcitotoxicity (EC50 of 0.86 μg DA/g) within 5–20 min of IC injection. All zebrafish receiving low-dose DA (0.47 μg DA/g) or vehicle only maintained normal behavior. Microarray analysis of symptomatic and asymptomatic exposures collectively yielded 306 differentially expressed genes (1.5-fold, p ≤ 0.05) predominately represented by signal transduction, ion transport, and transcription factor functional categories. Transcriptional profiles were suggestive of neuronal apoptosis following an overwhelming of protective adaptive pathways. Further, potential molecular biomarkers of neuropathic injury, including the zebrafish homolog of human NDRG4, were identified and may be relevant to DA exposure levels below that causing neurobehavioral injury. In general, DA-modulated gene expression was consistent with other model species thereby validating zebrafish as an appropriate vertebrate model to study mechanisms of DA neurotoxicity. These data provide a basis for identifying pathways of DA-induced injury as well as biomarkers of asymptomatic and symptomatic DA exposure levels. PMID:18936300

  8. Immunomodulatory effects upon in vitro exposure of California sea lion and southern sea otter peripheral blood leukocytes to domoic acid.

    PubMed

    Levin, Milton; Joshi, Dhanashree; Draghi, Andrew; Gulland, Frances M; Jessup, David; De Guise, Sylvain

    2010-04-01

    During red tide bloom events, the marine diatom Pseudo-nitzschia produces the toxin domoic acid (DA), which has been associated with stranding and mortality events involving California sea lions (Zalophus californianus) and southern sea otters (Enhydra lutris). In addition to these well-documented DA-induced neurotoxic events, there is increasing concern that DA may exert chronic effects, such as immunomodulation, which may potentially increase an individual's susceptibility to a number of opportunistic infections following nonlethal exposure. We investigated the effects of DA on innate (phagocytosis and respiratory burst) and adaptive (mitogen-induced lymphocyte proliferation) immune functions with the use of peripheral blood leukocytes collected from healthy California sea lions and southern sea otters upon in vitro exposure to 0 (unexposed control), 0.0001, 0.001, 0.01, 0.1, 1.0, 10, and 100 microM DA. Domoic acid did not significantly modulate phagocytosis or respiratory burst in either species. For California sea lions, DA significantly increased ConA-induced T-lymphocyte proliferation upon exposure to DA concentrations ranging from 0.0001 to 10 microM, resulting in a nonlinear dose-response curve. There was no effect on lymphocyte proliferation at the highest concentration of DA tested. No effects on lymphocyte proliferation were observed in southern sea otters. Importantly, the in vitro DA concentrations affecting T-cell proliferation were within or below the range of DA in serum measured in free-ranging California sea lions following natural exposure, suggesting a risk for immunomodulation in free-ranging animals. Understanding the risk for immunomodulation upon DA exposure will contribute in the health assessment and management of California sea lions and southern sea otters, as well as guide veterinarians and wildlife rehabilitators in caring for and treating afflicted animals. PMID:20688647

  9. Use of urinary trichloroacetic acid as an exposure biomarker of disinfection by-products in cancer studies.

    PubMed

    Salas, Lucas A; Gracia-Lavedan, Esther; Goñi, Fernando; Moreno, Victor; Villanueva, Cristina M

    2014-11-01

    Urinary trichloroacetic acid (TCAA) has been proposed as a valid exposure biomarker for ingested disinfection by-products (DBP) for reproductive studies. However, it has never been used in epidemiologic studies on cancer. We investigate the performance of urinary TCAA as a biomarker of DBP exposure in the framework of an epidemiologic study on cancer. We conducted home visits to collect tap water, first morning void urine, and a 48h fluid intake diary among 120 controls from a case-control study of colorectal cancer in Barcelona, Spain. We measured urine TCAA and creatinine, and 9 haloacetic acids and 4 trihalomethanes (THM) in tap water. Lifetime THM exposure was estimated based on residential history since age 18 plus routine monitoring data. Robust linear regressions were used to estimate mean change in urinary TCAA adjusted by covariates. Among the studied group, mean age was 74 years (range 63-85) and 41 (34%) were females. Mean total tap water consumption was 2.2l/48h (standard error, 0.1l/48h). Geometric mean urine TCAA excretion rate was 17.3pmol/min [95%CI: 14.0-21.3], which increased 2% for a 10% increase in TCAA ingestion and decreased with total tap water consumption (-17%/l), water intake outside home (-32%), plasmatic volume (-64%/l), in smokers (-79%), and in users of non-steroidal anti-inflammatory drugs (-50%). Urinary TCAA levels were not associated with lifetime THM exposure. In conclusion, our findings support that urine TCAA is not a valid biomarker in case-control studies of adult cancer given that advanced age, comorbidites and medication use are prevalent and are determinants of urine TCAA levels, apart from ingested TCAA levels. In addition, low TCAA concentrations in drinking water limit the validity of urine TCAA as an exposure biomarker. PMID:25462676

  10. Short-chain fatty acids: ready for prime time?

    PubMed

    Roy, Claude C; Kien, C Lawrence; Bouthillier, Lise; Levy, Emile

    2006-08-01

    The concept of colonic health has become a major target for the development of functional foods such as probiotics, prebiotics, and synbiotics. These bioactive agents have a profound effect on the composition of the microflora, as well as on the physiology of the colon, and display distinct health benefits. Dietary carbohydrates escaping digestion/absorption in the small bowel and prebiotics undergo fermentation in the colon and give rise to short-chain fatty acids (SCFA). As the main anions of the colon and the major source of energy for colonocytes, SCFA are rapidly absorbed by nonionic diffusion mostly but also by active transport mediated by a sodium-coupled transporter, thereby fostering the absorption of sodium and water. SCFA in general and butyrate in particular enhance the growth of lactobacilli and bifidobacteria and play a central role on the physiology and metabolism of the colon. The effect of prebiotics on cell proliferation, differentiation, apoptosis, mucin production, immune function, mineral absorption, lipid metabolism, and gastrointestinal (GI) peptides has been well documented experimentally. These effects seem to be largely mediated by SCFA, but evidence from human studies remains inconsistent. The food industry is making a leap of faith in their efforts to commercialize prebiotics and exploit potential health benefits. The future lies with the design of studies to further explore basic mechanisms, and gene expression in particular, but emphasis should be placed on human intervention trials. PMID:16870803

  11. Time dependent wettability of graphite upon ambient exposure: the role of water adsorption.

    PubMed

    Amadei, Carlo A; Lai, Chia-Yun; Heskes, Daan; Chiesa, Matteo

    2014-08-28

    We report the temporal evolution of the wettability of highly ordered pyrolytic graphite (HOPG) exposed to environmental conditions. Macroscopic wettability is investigated by static and dynamic contact angles (SCA and DCA) obtaining values comparable to the ones presented in the literature. SCA increases from ∼68° to ∼90° during the first hour of exposure after cleaving, whereas DCA is characterized by longer-scale (24 h) time evolution. We interpret these results in light of Fourier transform infrared spectroscopy, which indicates that the evolution of the HOPG wettability is due to adsorption of molecules from the surrounding atmosphere. This hypothesis is further confirmed by nanoscopic observations obtained by atomic force microscope (AFM)-based force spectroscopy, which monitor the evolution of surface properties with a spatial resolution superior to macroscopic experiments. Moreover, we observe that the results of macro- and nanoscale measurements evolve in similar fashion with time and we propose a quantitative correlation between SCA and AFM measurements. Our results suggest that the cause of the transition in the wettability of HOPG is due to the adsorption of hydrocarbon contaminations and water molecules from the environment. This is corroborated by annealing the HOPG is vacuum conditions at 150°, allowing the desorption of molecules on the surface, and thus re-establishing the initial macro and nano surface properties. Our findings can be used in the interpretation of the wettability of more complicated systems derived from HOPG (i.e., graphene).

  12. Time dependent wettability of graphite upon ambient exposure: The role of water adsorption

    SciTech Connect

    Amadei, Carlo A.; Lai, Chia-Yun; Heskes, Daan; Chiesa, Matteo

    2014-08-28

    We report the temporal evolution of the wettability of highly ordered pyrolytic graphite (HOPG) exposed to environmental conditions. Macroscopic wettability is investigated by static and dynamic contact angles (SCA and DCA) obtaining values comparable to the ones presented in the literature. SCA increases from ∼68° to ∼90° during the first hour of exposure after cleaving, whereas DCA is characterized by longer-scale (24 h) time evolution. We interpret these results in light of Fourier transform infrared spectroscopy, which indicates that the evolution of the HOPG wettability is due to adsorption of molecules from the surrounding atmosphere. This hypothesis is further confirmed by nanoscopic observations obtained by atomic force microscope (AFM)-based force spectroscopy, which monitor the evolution of surface properties with a spatial resolution superior to macroscopic experiments. Moreover, we observe that the results of macro- and nanoscale measurements evolve in similar fashion with time and we propose a quantitative correlation between SCA and AFM measurements. Our results suggest that the cause of the transition in the wettability of HOPG is due to the adsorption of hydrocarbon contaminations and water molecules from the environment. This is corroborated by annealing the HOPG is vacuum conditions at 150°, allowing the desorption of molecules on the surface, and thus re-establishing the initial macro and nano surface properties. Our findings can be used in the interpretation of the wettability of more complicated systems derived from HOPG (i.e., graphene)

  13. Near Real-Time Earthquake Exposure and Damage Assessment: An Example from Turkey

    NASA Astrophysics Data System (ADS)

    Kamer, Yavor; Çomoǧlu, Mustafa; Erdik, Mustafa

    2014-05-01

    Confined by infamous strike-slip North Anatolian Fault from the north and by the Hellenic subduction trench from the south Turkey is one of the most seismically active countries in Europe. Due this increased exposure and the fragility of the building stock Turkey is among the top countries exposed to earthquake hazard in terms of mortality and economic losses. In this study we focus recent and ongoing efforts to mitigate the earthquake risk in near real-time. We present actual results of recent earthquakes, such as the M6 event off-shore Antalya which occurred on 28 December 2013. Starting at the moment of detection, we obtain a preliminary ground motion intensity distribution based on epicenter and magnitude. Our real-time application is further enhanced by the integration of the SeisComp3 ground motion parameter estimation tool with the Earthquake Loss Estimation Routine (ELER). SeisComp3 provides the online station parameters which are then automatically incorporated into the ShakeMaps produced by ELER. The resulting ground motion distributions are used together with the building inventory to calculate expected number of buildings in various damage states. All these analysis are conducted in an automated fashion and are communicated within a few minutes of a triggering event. In our efforts to disseminate earthquake information to the general public we make extensive use of social networks such as Tweeter and collaborate with mobile phone operators.

  14. Prevalence and risk factors of non-carious cervical lesions related to occupational exposure to acid mists.

    PubMed

    Bomfim, Rafael Aiello; Crosato, Edgard; Mazzilli, Luiz Eugênio Nigro; Frias, Antonio Carlos

    2015-01-01

    This study evaluates the prevalence and risk factors of non-carious cervical lesions (NCCLs) in a Brazilian population of workers exposed and non-exposed to acid mists and chemical products. One hundred workers (46 exposed and 54 non-exposed) were evaluated in a Centro de Referência em Saúde do Trabalhador - CEREST (Worker's Health Reference Center). The workers responded to questionnaires regarding their personal information and about alcohol consumption and tobacco use. A clinical examination was conducted to evaluate the presence of NCCLs, according to WHO parameters. Statistical analyses were performed by unconditional logistic regression and multiple linear regression, with the critical level of p < 0.05. NCCLs were significantly associated with age groups (18-34, 35-44, 45-68 years). The unconditional logistic regression showed that the presence of NCCLs was better explained by age group (OR = 4.04; CI 95% 1.77-9.22) and occupational exposure to acid mists and chemical products (OR = 3.84; CI 95% 1.10-13.49), whereas the linear multiple regression revealed that NCCLs were better explained by years of smoking (p = 0.01) and age group (p = 0.04). The prevalence of NCCLs in the study population was particularly high (76.84%), and the risk factors for NCCLs were age, exposure to acid mists and smoking habit. Controlling risk factors through preventive and educative measures, allied to the use of personal protective equipment to prevent the occupational exposure to acid mists, may contribute to minimizing the prevalence of NCCLs. PMID:26154372

  15. Prevalence and risk factors of non-carious cervical lesions related to occupational exposure to acid mists.

    PubMed

    Bomfim, Rafael Aiello; Crosato, Edgard; Mazzilli, Luiz Eugênio Nigro; Frias, Antonio Carlos

    2015-01-01

    This study evaluates the prevalence and risk factors of non-carious cervical lesions (NCCLs) in a Brazilian population of workers exposed and non-exposed to acid mists and chemical products. One hundred workers (46 exposed and 54 non-exposed) were evaluated in a Centro de Referência em Saúde do Trabalhador - CEREST (Worker's Health Reference Center). The workers responded to questionnaires regarding their personal information and about alcohol consumption and tobacco use. A clinical examination was conducted to evaluate the presence of NCCLs, according to WHO parameters. Statistical analyses were performed by unconditional logistic regression and multiple linear regression, with the critical level of p < 0.05. NCCLs were significantly associated with age groups (18-34, 35-44, 45-68 years). The unconditional logistic regression showed that the presence of NCCLs was better explained by age group (OR = 4.04; CI 95% 1.77-9.22) and occupational exposure to acid mists and chemical products (OR = 3.84; CI 95% 1.10-13.49), whereas the linear multiple regression revealed that NCCLs were better explained by years of smoking (p = 0.01) and age group (p = 0.04). The prevalence of NCCLs in the study population was particularly high (76.84%), and the risk factors for NCCLs were age, exposure to acid mists and smoking habit. Controlling risk factors through preventive and educative measures, allied to the use of personal protective equipment to prevent the occupational exposure to acid mists, may contribute to minimizing the prevalence of NCCLs.

  16. Exposure to ionizing radiation reveals global dose- and time-dependent changes in the urinary metabolome of rat

    PubMed Central

    Mak, Tytus D.; Tyburski, John B.; Krausz, Kristopher W.; Kalinich, John F.; Gonzalez, Frank J.; Fornace, Albert J.

    2014-01-01

    The potential for exposures to ionizing radiation has increased in recent years. Although advances have been made, understanding the global metabolic response as a function of both dose and exposure time is challenging considering the complexity of the responses. Herein we report our findings on the dose- and time-dependency of the urinary response to ionizing radiation in the male rat using radiation metabolomics. Urine samples were collected from adult male rats, exposed to 0.5 to 10 Gy γ–radiation, both before from 6 to 72 h following exposures. Samples were analyzed by liquid chromatography coupled with time-of-flight mass spectrometry, and deconvoluted mass chromatographic data were initially analyzed by principal component analysis. However, the breadth and complexity of the data necessitated the development of a novel approach to summarizing biofluid constituents after exposure, called Visual Analysis of Metabolomics Package (VAMP). VAMP revealed clear urine metabolite profile differences to as little as 0.5 Gy after 6 h exposure. Via VAMP, it was discovered that the response to radiation exposure found in rat urine is characterized by an overall net down-regulation of ion excretion with only a modest number of ions excreted in excess over pre-exposure levels. Our results show both similarities and differences with the published mouse urine response and a dose- and time-dependent net decrease in urine ion excretion associated with radiation exposure. These findings mark an important step in the development of minimally invasive radiation biodosimetry. VAMP should have general applicability in metabolomics to visualize overall differences and trends in many sample sets. PMID:26557048

  17. Effect of acid concentration and treatment time on acid-alcohol modified jackfruit seed starch properties.

    PubMed

    Dutta, Himjyoti; Paul, Sanjib Kumar; Kalita, Dipankar; Mahanta, Charu Lata

    2011-09-15

    The properties of starch extracted from jackfruit (Artocarpus heterophyllus Lam.) seeds, collected from west Assam after acid-alcohol modification by short term treatment (ST) for 15-30min with concentrated hydrochloric acid and long term treatment (LT) for 1-15days with 1M hydrochloric acid, were investigated. Granule density, freeze thaw stability, solubility and light transmittance of the treated starches increased. A maximum decrease in the degree of polymerisation occurred in ST of 30min (2607.6). Jackfruit starch had 27.1±0.04% amylose content (db), which in ST initially decreased and then increased with the severity of treatment; in LT the effect was irregular. The pasting profile and granule morphology of the treated samples were severely modified. Native starch had the A-type crystalline pattern and crystalline structure increased on treatment. FTIR spectra revealed slight changes in bond stretching and bending. Colour measurement indicated that whiteness increased on treatment. Acid modified jackfruit seed starch can have applications in the food industry.

  18. Effect of acid concentration and treatment time on acid-alcohol modified jackfruit seed starch properties.

    PubMed

    Dutta, Himjyoti; Paul, Sanjib Kumar; Kalita, Dipankar; Mahanta, Charu Lata

    2011-09-15

    The properties of starch extracted from jackfruit (Artocarpus heterophyllus Lam.) seeds, collected from west Assam after acid-alcohol modification by short term treatment (ST) for 15-30min with concentrated hydrochloric acid and long term treatment (LT) for 1-15days with 1M hydrochloric acid, were investigated. Granule density, freeze thaw stability, solubility and light transmittance of the treated starches increased. A maximum decrease in the degree of polymerisation occurred in ST of 30min (2607.6). Jackfruit starch had 27.1±0.04% amylose content (db), which in ST initially decreased and then increased with the severity of treatment; in LT the effect was irregular. The pasting profile and granule morphology of the treated samples were severely modified. Native starch had the A-type crystalline pattern and crystalline structure increased on treatment. FTIR spectra revealed slight changes in bond stretching and bending. Colour measurement indicated that whiteness increased on treatment. Acid modified jackfruit seed starch can have applications in the food industry. PMID:25212133

  19. Evaluating methods for estimating space-time paths of individuals in calculating long-term personal exposure to air pollution

    NASA Astrophysics Data System (ADS)

    Schmitz, Oliver; Soenario, Ivan; Vaartjes, Ilonca; Strak, Maciek; Hoek, Gerard; Brunekreef, Bert; Dijst, Martin; Karssenberg, Derek

    2016-04-01

    Air pollution is one of the major concerns for human health. Associations between air pollution and health are often calculated using long-term (i.e. years to decades) information on personal exposure for each individual in a cohort. Personal exposure is the air pollution aggregated along the space-time path visited by an individual. As air pollution may vary considerably in space and time, for instance due to motorised traffic, the estimation of the spatio-temporal location of a persons' space-time path is important to identify the personal exposure. However, long term exposure is mostly calculated using the air pollution concentration at the x, y location of someone's home which does not consider that individuals are mobile (commuting, recreation, relocation). This assumption is often made as it is a major challenge to estimate space-time paths for all individuals in large cohorts, mostly because limited information on mobility of individuals is available. We address this issue by evaluating multiple approaches for the calculation of space-time paths, thereby estimating the personal exposure along these space-time paths with hyper resolution air pollution maps at national scale. This allows us to evaluate the effect of the space-time path and resulting personal exposure. Air pollution (e.g. NO2, PM10) was mapped for the entire Netherlands at a resolution of 5×5 m2 using the land use regression models developed in the European Study of Cohorts for Air Pollution Effects (ESCAPE, http://escapeproject.eu/) and the open source software PCRaster (http://www.pcraster.eu). The models use predictor variables like population density, land use, and traffic related data sets, and are able to model spatial variation and within-city variability of annual average concentration values. We approximated space-time paths for all individuals in a cohort using various aggregations, including those representing space-time paths as the outline of a persons' home or associated parcel

  20. Prenatal Exposure to Perfluorocarboxylic Acids (PFCAs) and Fetal and Postnatal Growth in the Taiwan Maternal and Infant Cohort Study

    PubMed Central

    Wang, Yan; Adgent, Margaret; Su, Pen-Hua; Chen, Hsiao-Yen; Chen, Pau-Chung; Hsiung, Chao A.; Wang, Shu-Li

    2016-01-01

    Background: Perfluorocarboxylic acids (PFCAs) are environmentally and biologically persistent synthetic chemicals. PFCAs include perfluorooctanoic acid (PFOA; C8) and long-chain PFCAs (C9–C20). Studies examining long-chain PFCAs and fetal and postnatal growth are limited. Objectives: We investigated the associations of prenatal exposure to long-chain PFCAs with fetal and postnatal growth. Methods: For 223 Taiwanese mothers and their term infants, we measured PFOA and four long-chain PFCAs (ng/mL) in third-trimester maternal serum; infant weight (kg), length and head circumference (cm) at birth; and childhood weight and height at approximately 2, 5, 8, and 11 years of age. For each sex, we used multivariable linear regression to examine associations between ln-transformed prenatal PFCAs and continuous infant measures, and logistic regression to examine small for gestational age (SGA). Linear mixed models were applied to prenatal PFCAs and childhood weight and height z-scores. Results: In girls, prenatal perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDeA), perfluoroundecanoic acid (PFUnDA), and perfluorododecanoic acid (PFDoDA) concentrations were inversely associated with birth weight [e.g., βbirth weight (kg) = –0.06, 95% CI: –0.11, –0.01 per 1 ln-unit PFUnDA increase]; prenatal PFDeA and PFUnDA were associated with elevated odds of SGA; and PFDeA, PFUnDA, and PFDoDA were associated with lower average childhood height z-score. In boys, prenatal PFNA, and PFDoDA were associated with reductions in height at certain ages in childhood, but not with size at birth. Conclusions: Prenatal exposure to long-chain PFCAs may interfere with fetal and childhood growth in girls, and childhood growth in boys. Citation: Wang Y, Adgent M, Su PH, Chen HY, Chen PC, Hsiung CA, Wang SL. 2016. Prenatal exposure to perfluorocarboxylic acids (PFCAs) and fetal and postnatal growth in the Taiwan Maternal and Infant Cohort Study. Environ Health Perspect 124:1794–1800;

  1. Refined Assessment of Human PM2.5 Exposure in Chinese city by Incorporating Time-activity Data

    NASA Astrophysics Data System (ADS)

    Zhu, W.; Wang, H.

    2015-12-01

    Since urban residents tend to spend a majority of time indoors throughout a day, it has been widely discussed in recent years, whether fixed-site monitoring PM2.5 ambient concentration is feasible as a surrogate of human PM2.5 exposure. Comprehensive understanding of residents' daily time-activity patterns (TAP) and possible indoor behavior are urgently needed to perform a more accurate estimate of human PM2.5exposure, especially in China, where is experiencing rapid urbanization.Field surveys of TAP were carried out in a Chinese city of Suzhou from 2014 to 2015 to evaluate PM2.5 exposure in various micro-environments (ME, e.g., residence, outdoors and in-transit). We gathered and analyzed urban residents' seasonal time-activity data using 24h retrospective time-location diaries, as well as diversified exposure-related indoor information (e.g. ventilation, environment tobacco smoke and cooking). PM2.5exposure is calculated through the incorporation of ambient concentration data, modified indoor/outdoor empirical functions and TAP. The spatial distributions of TAP-based exposure and static-population based exposure are also compared.Residents in Suzhou urban area spend over 65% of time at home and 90% indoors. There are significant temporal (season, day type) and socioeconomic differences (gender, age, education, living alone, having children at home, employment status, etc.) of time-activity distributions, which makes the sum of PM2.5 ME exposure differs notably from static-population based ambient exposure. People prefer to spend more time at home both in winter (P<0.05) and on weekends (P<0.001), less time outdoors in winter but more on weekends (P<0.001). Gender, education and living alone are negative associated with time spent home, while age, children at home and employment status are positively related. On the other hand, due to lack of monitoring stations in unban Suzhou, the inverse distance squared weighting method is not ideally performed and may be less

  2. Evaluation of exposure to organophosphate, carbamate, phenoxy acid, and chlorophenol pesticides in pregnant women from 10 Caribbean countries.

    PubMed

    Forde, Martin S; Robertson, Lyndon; Laouan Sidi, Elhadji A; Côté, Suzanne; Gaudreau, Eric; Drescher, Olivia; Ayotte, Pierre

    2015-09-01

    Pesticides are commonly used in tropical regions such as the Caribbean for both household and agricultural purposes. Of particular concern is exposure during pregnancy, as these compounds can cross the placental barrier and interfere with fetal development. The objective of this study was to evaluate exposure of pregnant women residing in 10 Caribbean countries to the following commonly used classes of pesticides in the Caribbean: organophosphates (OPs), carbamates, phenoxy acids, and chlorophenols. Out of 438 urine samples collected, 15 samples were randomly selected from each Caribbean country giving a total of 150 samples. Samples were analyzed for the following metabolites: six OP dialkylphosphate metabolites [dimethylphosphate (DMP), dimethylthiophosphate (DMTP), dimethyldithiophosphate (DMDTP), diethylphosphate (DEP), diethylthiophosphate (DETP) and diethyldithiophosphate (DEDTP)]; two carbamate metabolites [2-isopropoxyphenol (2-IPP) and carbofuranphenol]; one phenoxy acid 2,4-dichlorophenoxyacetic acid (2,4-D); and five chlorophenols [2,4-dichlorophenol (DCP), 2,5-dichlorophenol (2,5-DCP), 2,4,5-trichlorophenol (TCP), 2,4,6-trichlorophenol (2,4,6-TCP), and pentachlorophenol (PCP)]. OP metabolites were consistently detected in ≥60% of the samples from Antigua and Barbuda, Bermuda, and Jamaica. Of the carbamate metabolites, 2-IPP was detected in seven of the 10 Caribbean countries with a detection frequency around 30%, whereas carbofuranphenol was detected in only one sample. The detection frequency for the phenoxy acid 2,4-D ranged from 20% in Grenada to a maximum of 67% in Belize. Evidence of exposure to chlorophenol pesticides was also established with 2,4-DCP by geometric means ranging from 0.52 μg L(-1) in St Lucia to a maximum of 1.68 μg L(-1) in Bermuda. Several extreme concentrations of 2,5-DCP were detected in four Caribbean countries-Belize (1100 μg L(-1)), Bermuda (870 μg L(-1)), Jamaica (1300 μg L(-1)), and St Kitts and Nevis (1400 μg L(-1

  3. Comprehensive profiling of mercapturic acid metabolites from dietary acrylamide as short-term exposure biomarkers for evaluation of toxicokinetics in rats and daily internal exposure in humans using isotope dilution ultra-high performance liquid chromatography tandem mass spectrometry.

    PubMed

    Zhang, Yu; Wang, Qiao; Cheng, Jun; Zhang, Jingshun; Xu, Jiaojiao; Ren, Yiping

    2015-09-24

    Mercapturic acid metabolites from dietary acrylamide are important short-term exposure biomarkers for evaluating the in vivo toxicity of acrylamide. Most of studies have focused on the measurement of two metabolites, N-acetyl-S-(2-carbamoylethyl)-L-cysteine (AAMA) and N-acetyl-S-(2-carbamoyl-2-hydroxyethyl)-L-cysteine (GAMA). Thus, the comprehensive profile of acrylamide urinary metabolites cannot be fully understood. We developed an isotope dilution ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method for the simultaneous determination of all four mercapturic acid adducts of acrylamide and its primary metabolite glycidamide under the electroscopy ionization negative (ESI-) mode in the present study. The limit of detection (LOD) and limit of quantification (LOQ) of the analytes ranged 0.1-0.3 ng/mL and 0.4-1.0 ng/mL, respectively. The recovery rates with low, intermediate and high spiking levels were calculated as 95.5%-105.4%, 98.2%-114.0% and 92.2%-108.9%, respectively. Acceptable within-laboratory reproducibility (RSD<7.0%) substantially supported the use of current method for robust analysis. Rapid pretreatment procedures and short run time (8 min per sample) ensured good efficiency of metabolism profiling, indicating a wide application for investigating short-term internal exposure of dietary acrylamide. Our proposed UHPLC-MS/MS method was successfully applied to the toxicokinetic study of acrylamide in rats. Meanwhile, results of human urine analysis indicated that the levels of N-acetyl-S-(2-carbamoylethyl)-L-cysteine-sulfoxide (AAMA-sul), which did not appear in the mercapturic acid metabolites in rodents, were more than the sum of GAMA and N-acetyl-S-(1-carbamoyl-2-hydroxyethyl)-L-cysteine (iso-GAMA). Thus, AAMA-sul may alternatively become a specific biomarker for investigating the acrylamide exposure in humans. Current proposed method provides a substantial methodology support for comprehensive profiling of

  4. Fatty Acids Composition and Biofilm Production of Attenuated Salmonella typhimurium dam and seqA Mutants After Exposure to UV-C.

    PubMed

    Abdelwaheb, Chatti; Lobna, Maalej; Bouchra, BelHadj Abdallah; Selma, Kloula; Ahmed, Landoulsi

    2015-10-01

    The goal of this work was the investigation of correlation between some peculiarities of membrane fatty acids composition, biofilm formation, and motility of dam and/or seqA mutants in Salmonella typhimurium bacterial cells and UV-C radiations. The exposure changed the fatty acids composition of dam and seqA/dam strains. Significant increase of unsaturated fatty acids was observed. Swarming and swimming were enhanced only in dam mutant and biofilm formation increased significantly in all tested strains after UV-C exposure. These results suggest that increased sensitivity toward UV-C rays in dam strains might be due to fatty acid alteration.

  5. Omega-3 Fatty Acid Consumption and Prostate Cancer: A Review of Exposure Measures and Results of Epidemiological Studies.

    PubMed

    Dinwiddie, Michael T; Terry, Paul D; Whelan, Jay; Patzer, Rachel E

    2016-07-01

    Animal studies have shown that dietary omega-3 polyunsaturated fatty acids (n-3) may play a role in the development of prostate cancer, but the results of epidemiologic studies have been equivocal. Associations in humans may vary depending on study design, measurement methodology of fatty acid intake, intake ranges, and stage of cancer development. To address this, we identified 36 published studies through PubMed (Medline) from 1993 through 2013 on long-chain n-3s and prostate cancer. Exposure measurements included dietary assessment and biomarker levels. Associations for total, early, and late stage prostate cancer were examined by subgroup of study design and exposure measure type and by using forest plots to illustrate the relative strength of associations within each subgroup. We also tested for potential threshold effects by considering studies that included measurement cut-points that met intake levels recommended by the American Heart Association. We found no consistent evidence supporting a role of n-3s in either the causation or prevention of prostate cancer at any stage or grade. Results did not vary appreciably by study design, exposure measurement, intake level, or stage of cancer development.

  6. Timing and Duration of Traffic-related Air Pollution Exposure and the Risk for Childhood Wheeze and Asthma

    PubMed Central

    Brunst, Kelly J.; Brokamp, Cole; Bernstein, David; Reponen, Tiina; Lockey, James; Khurana Hershey, Gurjit K.; Levin, Linda; Grinshpun, Sergey A.; LeMasters, Grace

    2015-01-01

    Rationale: The timing and duration of traffic-related air pollution (TRAP) exposure may be important for childhood wheezing and asthma development. Objectives: We examined the relationship between TRAP exposure and longitudinal wheezing phenotypes and asthma at age 7 years. Methods: Children completed clinical examinations annually from age 1 year through age 4 years and age 7 years. Parental-reported wheezing was assessed at each age, and longitudinal wheezing phenotypes (early-transient, late-onset, persistent) and asthma were defined at age 7 years. Participants’ time-weighted exposure to TRAP, from birth through age 7 years, was estimated using a land-use regression model. The relationship between TRAP exposure and wheezing phenotypes and asthma was examined. Measurements and Main Results: High TRAP exposure at birth was significantly associated with both transient and persistent wheezing phenotypes (adjusted odds ratio [aOR] = 1.64; 95% confidence interval [CI], 1.04–2.57 and aOR = 2.31; 95% CI, 1.28–4.15, respectively); exposure from birth to age 1 year and age 1 to 2 years was also associated with persistent wheeze. Only children with high average TRAP exposure from birth through age 7 years were at significantly increased risk for asthma (aOR = 1.71; 95% CI, 1.01–2.88). Conclusions: Early-life exposure to TRAP is associated with increased risk for persistent wheezing, but only long-term exposure to high levels of TRAP throughout childhood was associated with asthma development. PMID:26106807

  7. Real-time monitoring of nucleic acid ligation in homogenous solutions using molecular beacons.

    PubMed

    Tang, Zhiwen; Wang, Kemin; Tan, Weihong; Li, Jun; Liu, Lingfeng; Guo, Qiuping; Meng, Xiangxian; Ma, Changbei; Huang, Shasheng

    2003-12-01

    Nucleic acids ligation is a vital process in the repair, replication and recombination of nucleic acids. Traditionally, it is assayed by denatured gel electrophoresis and autoradiography, which are not sensitive, and are complex and discontinuous. Here we report a new approach for ligation monitoring using molecular beacon DNA probes. The molecular beacon, designed in such a way that its sequence is complementary with the product of the ligation process, is used to monitor the nucleic acid ligation in a homogeneous solution and in real-time. Our method is fast and simple. We are able to study nucleic acids ligation kinetics conveniently and to determine the activity of DNA ligase accurately. We have studied different factors that influence DNA ligation catalyzed by T4 DNA ligase. The major advantages of our method are its ultrasensitivity, excellent specificity, convenience and real-time monitoring in homogeneous solution. This method will be widely useful for studying nucleic acids ligation process and other nucleic acid interactions.

  8. How accurate and precise are limited sampling strategies in estimating exposure to mycophenolic acid in people with autoimmune disease?

    PubMed

    Abd Rahman, Azrin N; Tett, Susan E; Staatz, Christine E

    2014-03-01

    Mycophenolic acid (MPA) is a potent immunosuppressant agent, which is increasingly being used in the treatment of patients with various autoimmune diseases. Dosing to achieve a specific target MPA area under the concentration-time curve from 0 to 12 h post-dose (AUC12) is likely to lead to better treatment outcomes in patients with autoimmune disease than a standard fixed-dose strategy. This review summarizes the available published data around concentration monitoring strategies for MPA in patients with autoimmune disease and examines the accuracy and precision of methods reported to date using limited concentration-time points to estimate MPA AUC12. A total of 13 studies were identified that assessed the correlation between single time points and MPA AUC12 and/or examined the predictive performance of limited sampling strategies in estimating MPA AUC12. The majority of studies investigated mycophenolate mofetil (MMF) rather than the enteric-coated mycophenolate sodium (EC-MPS) formulation of MPA. Correlations between MPA trough concentrations and MPA AUC12 estimated by full concentration-time profiling ranged from 0.13 to 0.94 across ten studies, with the highest associations (r (2) = 0.90-0.94) observed in lupus nephritis patients. Correlations were generally higher in autoimmune disease patients compared with renal allograft recipients and higher after MMF compared with EC-MPS intake. Four studies investigated use of a limited sampling strategy to predict MPA AUC12 determined by full concentration-time profiling. Three studies used a limited sampling strategy consisting of a maximum combination of three sampling time points with the latest sample drawn 3-6 h after MMF intake, whereas the remaining study tested all combinations of sampling times. MPA AUC12 was best predicted when three samples were taken at pre-dose and at 1 and 3 h post-dose with a mean bias and imprecision of 0.8 and 22.6 % for multiple linear regression analysis and of -5.5 and 23.0 % for

  9. Influence of bicarbonate and humic acid on effects of chronic waterborne lead exposure to the fathead minnow (Pimephales promelas).

    PubMed

    Mager, Edward M; Brix, Kevin V; Grosell, Martin

    2010-01-31

    Historically, the USEPA has only considered water hardness when establishing acute and chronic water quality criteria (WQC) for lead (Pb) in freshwater. Yet, recent evidence suggests that hardness may not be protective during chronic Pb exposure and that other factors (e.g., dissolved organic carbon (DOC) and alkalinity) influence toxicity. In fact, we have recently shown that Ca(2+) (as CaSO(4)) does not protect against Pb accumulation in fathead minnows (Pimephales promelas) during chronic exposures whereas DOC as humic acid (HA) clearly does. To more clearly define the water chemistry parameters mediating chronic Pb toxicity we carried out 300 d exposures to study the influence of DOC and alkalinity on Pb accumulation and toxicity to fathead minnows at 2 different Pb concentrations (170 and 580 nM (35 and 120 microg/L)). Alkalinity was adjusted by addition of 500 microM NaHCO(3) and DOC by addition of 4 mg/L HA. Fish were collected at 4, 30, 150 and 300 d of exposure to measure growth and Pb accumulation. Breeding assays (21 d) were performed at the end of these exposures to assess reproductive and larval behavioral endpoints. To determine whether effects were acute or chronic, switched breeding exposures were performed in which control breeders were transferred to either high or low Pb conditions and Pb-exposed breeders transferred to tap water without Pb. Mortality and growth effects were observed primarily in the high Pb treatments and within the first 10 d of exposure. Strong protection against Pb accumulation was afforded by increased DOC at both Pb concentrations. Increased alkalinity also appeared to moderately reduce Pb accumulation although not to the level of statistical significance. Tissue distribution of Pb was analyzed at 300 d and was found to accumulate mostly in bone, gill, intestine and kidney. Unexpectedly, high Pb reduced total reproductive output and increased average egg mass in the HCO(3)(-) and DOC treatments but not in the control water

  10. Experimental model of lead nephropathy. II. Effect of removal from lead exposure and chelation treatment with dimercaptosuccinic acid (DMSA).

    PubMed

    Khalil-Manesh, F; Gonick, H C; Cohen, A; Bergamaschi, E; Mutti, A

    1992-06-01

    Male Sprague-Dawley rats were exposed to high-dose (0.5%) lead acetate for periods ranging from 1 to 9 months; then lead exposure was discontinued, and animals were sacrificed after 12 months. Controls were pair-fed. Two additional groups of low-dose (0.01%) and high-dose (0.5%) rats were exposed to lead for 6 months, then lead was discontinued and the rats were treated with three 5-day courses of 0.5% DMSA (dimercaptosuccinic acid) over the next 6 months. Controls were rats exposed to lead for 6 months, then removed from exposure for 6 months without receiving DMSA. Low-dose lead-treated rats showed no significant pathological changes with or without DMSA treatment, but exhibited a significant increase in GFR after DMSA. High-dose lead-treated animals showed no functional or pathological changes when lead exposure was discontinued after 1 month. However, when duration of exposure was 6 or 9 months, GFR was decreased and serum creatinine and urea nitrogen were increased as compared to controls. Tubulointerstitial disease was severe. Administration of DMSA resulted in an improvement in GFR and a decrease in albuminuria, together with a reduction in size and number of nuclear inclusion bodies in proximal tubules. However, tubulointerstitial scarring was only minimally reduced. It may be concluded that, except for brief initial exposure, discontinuation of high-dose lead exposure fails to reverse lead-induced renal damage. Treatment with the chelator, DMSA, improves renal function but has less effect on pathological alterations. As GFR improved after DMSA treatment in both low-dose and high-dose lead-treated rats, irrespective of the degree of pathological alterations, it may be concluded that the DMSA effect is most likely mediated by hemodynamic changes.

  11. Assessment of Two Portable Real-Time Particle Monitors Used in Nanomaterial Workplace Exposure Evaluations

    PubMed Central

    Liu, Yuewei; Beaucham, Catherine C.; Pearce, Terri A.; Zhuang, Ziqing

    2014-01-01

    Background Nanoparticle emission assessment technique was developed to semi-quantitatively evaluate nanomaterial exposures and employs a combination of filter based samples and portable real-time particle monitors, including a condensation particle counter (CPC) and an optical particle counter (OPC), to detect nanomaterial releases. This laboratory study evaluated the results from CPC and OPC simultaneously measuring a polydisperse aerosol to assess their variability and accuracy. Methods and Results Two CPCs and two OPCs were used to evaluate a polydisperse sodium chloride aerosol within an enclosed chamber. The measurement results for number concentration versus time were compared between paired particle monitors of the same type, and to results from the Scanning Mobility Particle Spectrometer (SMPS) which was widely used to measure concentration of size-specific particles. According to analyses by using the Bland-Altman method, the CPCs displayed a constant mean percent difference of −3.8% (95% agreement limits: −9.1 to 1.6%; range of 95% agreement limit: 10.7%) with the chamber particle concentration below its dynamic upper limit (100,000 particles per cubic centimeter). The mean percent difference increased from −3.4% to −12.0% (range of 95% agreement limits: 7.1%) with increasing particle concentrations that were above the dynamic upper limit. The OPC results showed the percent difference within 15% for measurements in particles with size ranges of 300 to 500 and 500 to 1000 regardless of the particle concentration. Compared with SMPS measurements, the CPC gave a mean percent difference of 22.9% (95% agreement limits: 10.5% to 35.2%); whereas the measurements from OPC were not comparable. Conclusions This study demonstrated that CPC and OPC are useful for measuring nanoparticle exposures but the results from an individual monitor should be interpreted based upon the instrument's technical parameters. Future research should challenge these monitors

  12. Timing of Galectin-1 Exposure Differentially Modulates Nipah Virus Entry and Syncytium Formation in Endothelial Cells

    PubMed Central

    Garner, Omai B.; Yun, Tatyana; Pernet, Olivier; Aguilar, Hector C.; Park, Arnold; Bowden, Thomas A.; Freiberg, Alexander N.

    2014-01-01

    ABSTRACT Nipah virus (NiV) is a deadly emerging enveloped paramyxovirus that primarily targets human endothelial cells. Endothelial cells express the innate immune effector galectin-1 that we have previously shown can bind to specific N-glycans on the NiV envelope fusion glycoprotein (F). NiV-F mediates fusion of infected endothelial cells into syncytia, resulting in endothelial disruption and hemorrhage. Galectin-1 is an endogenous carbohydrate-binding protein that binds to specific glycans on NiV-F to reduce endothelial cell fusion, an effect that may reduce pathophysiologic sequelae of NiV infection. However, galectins play multiple roles in regulating host-pathogen interactions; for example, galectins can promote attachment of HIV to T cells and macrophages and attachment of HSV-1 to keratinocytes but can also inhibit influenza entry into airway epithelial cells. Using live Nipah virus, in the present study, we demonstrate that galectin-1 can enhance NiV attachment to and infection of primary human endothelial cells by bridging glycans on the viral envelope to host cell glycoproteins. In order to exhibit an enhancing effect, galectin-1 must be present during the initial phase of virus attachment; in contrast, addition of galectin-1 postinfection results in reduced production of progeny virus and syncytium formation. Thus, galectin-1 can have dual and opposing effects on NiV infection of human endothelial cells. While various roles for galectin family members in microbial-host interactions have been described, we report opposing effects of the same galectin family member on a specific virus, with the timing of exposure during the viral life cycle determining the outcome. IMPORTANCE Nipah virus is an emerging pathogen that targets endothelial cells lining blood vessels; the high mortality rate (up to 70%) in Nipah virus infections results from destruction of these cells and resulting catastrophic hemorrhage. Host factors that promote or prevent Nipah virus

  13. Urinary t,t-muconic acid as an indicator of exposure to benzene.

    PubMed Central

    Inoue, O; Seiji, K; Nakatsuka, H; Watanabe, T; Yin, S N; Li, G L; Cai, S X; Jin, C; Ikeda, M

    1989-01-01

    A method for rapidly determining t,t-muconic acid (MA) by high performance liquid chromatography was developed and successfully applied to urine samples from 152 workers exposed to benzene (64 men, 88 women) and 213 non-exposed controls (113 men, 100 women). The MA concentrations in urine correlated linearly with time weighted average benzene concentrations in the breath zone air of workers. A cross sectional balance study showed that about 2% of benzene inhaled is excreted into the urine as MA. The MA concentrations in the urine of the non-exposed was below the detection limit (less than 0.1 mg/l) in most cases, and the 95% lower confidence limit of MA for those exposed to benzene at 5 ppm (5.0 mg/l as a non-corrected value) was higher than the 97.5%-tile values for the non-exposed (1.4 mg/l). In practice, it was possible to separate those exposed to 6-7 ppm benzene from the non-exposed by means of urine analysis for MA. The urinary MA concentration was suppressed by coexposure to toluene. PMID:2923822

  14. Fibroblasts behavior after N-acetylcysteine and amino acids exposure: extracellular matrix gene expression.

    PubMed

    Avantaggiato, Anna; Palmieri, Annalisa; Bertuzzi, Gianluigi; Carinci, Francesco

    2014-06-01

    Reactive oxygen species (ROS) are chemically reactive molecules with impaired electrons that make them unstable and able to react easily with a great variety of molecules. The main targets of ROS are DNA, proteins, and membrane phospholipids. In the skin, ROS are able to affect the production of collagen and elastin, the main components of the extracellular matrix (ECM). This action contributes to the skin's aging. N-Acetylcysteine (NAC) is an acetylated cysteine residue with excellent anti-oxidant activity that boosts glutathione (GSH) levels. This study evaluates the effect of a solution of NAC and amino acids, which is used in aesthetic medicine as an intra-dermal injective treatment, on fibroblast behavior. To this aim, the expression levels of some ECM-related genes (HAS1, HYAL1 ELN, ELANE, MMP2, MMP3, MMP13, COL1A1, COL3A1) were analyzed on cultured dermal fibroblasts using real-time reverse transcription polymerase chain reaction (RT-PCR). All but two collagen genes were up-regulated after 24 hr of treatment. PMID:24438160

  15. Effect of heat exposure on thermoregulation and hockey-specific response time in field hockey goalkeepers.

    PubMed

    Malan, Marcelle; Dawson, Brian; Goodman, Carmel; Peeling, Peter

    2010-05-01

    This study examined the thermoregulatory responses in field hockey goalkeepers during games (Part A), and assessed the effect of heat stress on hockey-specific response time (Part B). In Part A, core temperature (T(c)), skin temperature (T(sk)), body mass, fluid consumption and heart rate (HR) responses of six goalkeepers during two premier level club games in the Western Australian (winter) hockey season were recorded. Part B assessed the same measures, plus a response time test on four goalkeepers playing a simulated game inside a climate chamber in cool (COOL: 20 degrees C, 40% RH) and hot (HOT: 35 degrees C, 40% RH) conditions. In Part A, the mean (+/-SD) T(c) and T(sk) measured in games was 38.49+/-0.20 degrees C and 34.99+/-0.99 degrees C, with increases from baseline of 1.34+/-0.19 degrees C and 1.08+/-0.30 degrees C, respectively. Most of the increase in T(c) resulted from the pre-game warm-up. In Part B, T(c) and T(sk) only increased significantly (p<0.05) from baseline in the HOT condition (0.62+/-0.18 degrees C and 1.61+/-0.82 degrees C, respectively). Response time was significantly slower (0.87+/-0.14s, p<0.01) after heat exposure, compared to COOL (0.75+/-0.15s), but the number of correct responses was not affected. For optimal performance, careful attention should be given to strategies to limit T(c) increases in field hockey goalkeepers during matches.

  16. Monitoring of 1-min personal particulate matter exposures in relation to voice-recorded time-activity data.

    PubMed

    Quintana, P J; Valenzia, J R; Delfino, R J; Liu, L J

    2001-12-01

    Recent studies on the association between exposures to airborne particulate matter (PM) and disease have identified short-term peaks in PM exposures as posing especial health threats. Lightweight personal instruments are needed to characterize short-term exposures to PM and to identify the most important sources of high PM excursions. In this study, we measured exposure to fine PM using a small personal nephelometer (pDR; MIE, Inc) to investigate the utility of this instrument in identifying activities and microenvironments most associated with high PM exposures and the magnitude and duration of peaks in PM exposures. Ten adult volunteers wore a pDR recording PM concentrations at 1-min time intervals for 1 week each. PM concentrations were measured by the pDR in units of microg/m(3) based on light scatter. The use of a time-stamped voice recorder enabled activity and location to be continuously documented in real time. In addition, a small, inexpensive light intensity logger was affixed to the pDR to evaluate the potential of this instrument to assist in verifying wearer- recorded data. For each person, patterns of PM exposure were remarkably consistent over daily activities and showed large excursions associated with specific indoor and outdoor microenvironments and activities, such as cooking. When the magnitude and duration of excursions in PM were analyzed, we found that high PM levels occurred in relatively few of the minutes measured but comprised a substantial fraction of the total exposure to PM. Fifteen-minute averaged PM levels were found to be as much as 10 times the daily average. When the data were analyzed with a generalized estimating equation model to account for effects of autocorrelation and clustering, PM exposure was significantly higher during subject-reported events including barbeque, yard work, being near pets or construction activities, cooking, and environmental tobacco smoke exposure, as compared with periods with no pollution events

  17. Tissue specific uptake and elimination of perfluoroalkyl acids (PFAAs) in adult rainbow trout (Oncorhynchus mykiss) after dietary exposure.

    PubMed

    Falk, Sandy; Failing, Klaus; Georgii, Sebastian; Brunn, Hubertus; Stahl, Thorsten

    2015-06-01

    Tissue specific uptake and elimination of perfluoroalkyl acids (PFAAs) were studied in rainbow trout (Oncorhynchus mykiss). Adult trout were exposed to perfluorobutane sulfonic acid (PFBS), perfluorohexane sulfonic acid (PFHxS), perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA) and perfluorononanoic acid (PFNA) via food over a time period of 28d. In the following 28-d depuration period the fish were fed PFAA-free food. At defined sampling times four animals were removed from the experimental tank, euthanized and dissected. Muscle, liver, kidneys, gills, blood, skin and carcass were examined individually. At the end of the accumulation phase between 0.63% (PFOA) and 15.5% (PFOS) of the absolute, applied quantity of PFAAs was recovered in the whole fish. The main target organ was the liver with recovery rates between 0.11% (PFBS) and 4.01% (PFOS) of the total amount of ingested PFAAs. Perfluoroalkyl sulfonic acids were taken up more readily and had longer estimated elimination half-lives than perfluoroalkyl carboxylic acids of the same chain length. The longest estimated elimination half-lives were found to be for PFOS between 8.4d in muscle tissue and 20.4d in the liver and for PFNA between 8.2d in the blood and 11.6d in the liver.

  18. Cartilage and bone malformations in the head of zebrafish (Danio rerio) embryos following exposure to disulfiram and acetic acid hydrazide

    SciTech Connect

    Strecker, Ruben; Weigt, Stefan; Braunbeck, Thomas

    2013-04-15

    In order to investigate teratogenic effects, especially on cartilage and bone formation, zebrafish embryos were exposed for 144 h to the dithiocarbamate pesticide disulfiram (20–320 μg/L) and acetic acid hydrazide (0.375–12 g/L), a degradation product of isoniazid. After fixation and full-mount staining, disulfiram could be shown to induce strong cartilage malformations after exposure to ≥ 80 μg/L, whereas acetic acid hydrazide caused cartilage alterations only from 1.5 g/L. Undulating notochords occurred after exposure to disulfiram even at the lowest test concentration of 20 μg/L, whereas at the two lowest concentrations of acetic acid hydrazide (0.375 and 0.75 g/L) mainly fractures of the notochord were observed. Concentrations of acetic acid hydrazide ≥ 1.5 g/L resulted in undulated notochords similar to disulfiram. Cartilages and ossifications of the cranium, including the cleithrum, were individually analyzed assessing the severity of malformation and the degree of ossification in a semi-quantitative approach. Cartilages of the neurocranium such as the ethmoid plate proved to be more stable than cartilages of the pharyngeal skeleton such as Meckel's cartilage. Hence, ossification proved significantly more susceptible than cartilage. The alterations induced in the notochord as well as in the cranium might well be of ecological relevance, since notochord malformation is likely to result in impaired swimming and cranial malformation might compromise regular food uptake. - Highlights: ► Disulfiram and acetic acid hydrazide as notochord, cartilage and bone teratogens ► Zebrafish embryos to model effects on single cartilages and bones in the head ► LC50 calculation and head length measurements after six days post-fertilization ► Lethality, head length and teratogenic effects are dose-dependent. ► Cartilages of the neurocranium are the most stable elements in the head.

  19. The Effects of Lead Exposure on Serum Uric Acid and Hyperuricemia in Chinese Adults: A Cross-Sectional Study.

    PubMed

    Dai, Haijiang; Huang, Zhijun; Deng, Qihong; Li, Ying; Xiao, Ting; Ning, Xingping; Lu, Yao; Yuan, Hong

    2015-08-18

    The aim of this study was to assess the correlation between blood lead levels and both serum uric acid and hyperuricemia in adult residents living within an area of China with lead pollution. We conducted a cross-sectional analysis of 2120 subjects (1180 of whom were male) between the ages of 20 and 75 years who had undergone health examinations at the Centers for Disease Control and Prevention (CDC) in a lead-polluted area of China between January 2013 and August 2014. Blood lead was positively correlated with serum uric acid in both males (r = 0.095, p = 0.001) and females (r = 0.134, p < 0.001). Multivariate linear regression analysis demonstrated that for males, blood lead (p = 0.006), age (p = 0.001), current smoking (p = 0.012), education (p = 0.001), triglycerides (TG) (p < 0.001), and serum creatinine (p < 0.001) were independently associated with serum uric acid. For females, blood lead (p < 0.001), body mass index (BMI) (p = 0.009), and TG (p < 0.001) were independently associated with serum uric acid. After multiple adjustments, blood lead was significantly associated with a higher prevalence of hyperuricemia when female subjects were categorized into quartiles (for the highest quartile vs. the lowest quartile, odds ratio (OR) = 2.190; 95% confidence interval (CI): 1.106-4.338; p = 0.025); however, no such association was observed for male subjects. Continuous lead exposure has an independent impact on serum uric acid for both males and females, although this impact is more pronounced for females than for males. Lead exposure is significantly associated with hyperuricemia for females but not for males.

  20. Effects of short-term acid and aluminum exposure on the parr-smolt transformation in Atlantic salmon (Salmo salar): Disruption of seawater tolerance and endocrine status

    USGS Publications Warehouse

    Monette, M.Y.; Bjornsson, Bjorn Thrandur; McCormick, S.D.

    2008-01-01

    Episodic acidification resulting in increased acidity and inorganic aluminum (Ali) is known to interfere with the parr-smolt transformation of Atlantic salmon (Salmo salar), and has been implicated as a possible cause of population decline. To determine the extent and mechanism(s) by which short-term acid/Al exposure compromises smolt development, Atlantic salmon smolts were exposed to either control (pH 6.7-6.9) or acid/Al (pH 5.4-6.3, 28-64 ??g l-1 Ali) conditions for 2 and 5 days, and impacts on freshwater (FW) ion regulation, seawater (SW) tolerance, plasma hormone levels and stress response were examined. Gill Al concentrations were elevated in all smolts exposed to acid/Al relative to controls confirming exposure to increased Ali. There was no effect of acid/Al on plasma ion concentrations in FW however, smolts exposed to acid/Al followed by a 24 h SW challenge exhibited greater plasma Cl- levels than controls, indicating reduced SW tolerance. Loss of SW tolerance was accompanied by reductions in gill Na+,K+-ATPase (NKA) activity and Na+,K+,2Cl- (NKCC) cotransporter protein abundance. Acid/Al exposure resulted in decreased plasma insulin-like growth factor (IGF-I) and 3,3???,5???-triiodo-l-thyronine (T3) levels, whereas no effect of treatment was seen on plasma cortisol, growth hormone (GH), or thyroxine (T4) levels. Acid/Al exposure resulted in increased hematocrit and plasma glucose levels in FW, but both returned to control levels after 24 h in SW. The results indicate that smolt development and SW tolerance are compromised by short-term exposure to acid/Al in the absence of detectable impacts on FW ion regulation. Loss of SW tolerance during short-term acid/Al exposure likely results from reductions in gill NKA and NKCC, possibly mediated by decreases in plasma IGF-I and T3. ?? 2008 Elsevier Inc.

  1. Perfluoroalkyl acids (PFAAs) in indoor and outdoor dusts around a mega fluorochemical industrial park in China: Implications for human exposure.

    PubMed

    Su, Hongqiao; Lu, Yonglong; Wang, Pei; Shi, Yajuan; Li, Qifeng; Zhou, Yunqiao; Johnson, Andrew C

    2016-09-01

    The manufacture of fluorochemicals can lead to high levels of perfluoroalkyl acids (PFAAs) contaminating the surrounding environment and consequently elevated exposure to the local residents. In this study, measurements of PFAAs associated with indoor and outdoor dusts around a mega fluorochemical industrial park (FIP) were made. Perfluorooctanoic acid (PFOA) and short-chain perfluoroalkyl carboxylic acids (C4-C7 PFCAs) were the predominant forms in all samples. The signature of the PFAAs in dusts in the local area matched that found within the FIP complex. The contamination plume in the local area could be linked to the prevailing wind direction starting from the FIP. The dust concentrations decreased exponentially with distance from the FIP (noticeably in the first 5km). PFAAs contamination could be detected at the furthest location, 20km away from the FIP. The concentrations of PFAAs were higher in indoor dust (73-13,500ng/g, median: 979ng/g) than those in outdoor dust (5-9495ng/g, median: 62ng/g) at every location. The highest estimated daily intake of PFOA via dust ingestion (26.0ng/kg·bw/day) was for toddlers (2-5years) living 2km away from the FIP, which is posing human health risk, though exposure remains within the provisional tolerable daily intake values. PMID:27393120

  2. Influence of yeast strain and aging time on free amino acid changes in sparkling ciders.

    PubMed

    Suárez Valles, Belén; Palacios García, Noemí; Rodríguez Madrera, Roberto; Picinelli Lobo, Anna

    2005-08-10

    An analytical method for the determination of free amino acids in ciders is reported. It is based on high-performance liquid chromatography with an automatic precolumn derivatization with o-phthaldehyde and 3-mercaptopropionic acid and diode array detection. The method was applied to monitor the amino acids during second fermentation of sparkling ciders. This paper reports the influence of yeast strains and aging time on the amino acid composition of sparkling ciders. The application of principal component analysis enables the ciders to be differentiated on the basis of the two factors considered (yeast strain and aging time). The first principal component, which accounts for 58% of the total variance, achieved the separation according to aging time with serine, glycine, alanine, valine, ornithine, leucine, and lysine as the most important variables. The second principal component, accounting for 28% of the explained variance, is closely related to aspartic acid and asparagine and separates the samples according to the yeast strain. PMID:16076126

  3. Positive Adaptive State: Microarray Evaluation of Gene Expression in Salmonella Enterica Typhimurium Upon Exposure to Sub-Therapeutic Levels of Nalidixic Acid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In order to evaluate changes in gene expression that occur upon exposure to sub-therapeutic levels of a quinolones antibioitic, Salmonella enterica Typhimurium ATCC# 14028 was exposed to 1.6 ug/L of nalidixic acid (NA). Microarray analysis of the expression profile during exposure to NA was compared...

  4. GENE EXPRESSION PROFILING OF MOUSE SKIN AND PAPILLOMAS FOLLOWING CHRONIC EXPOSURE TO MONOMETHYLARSONOUS ACID IN K6/ODC TRANSGENIC MICE

    EPA Science Inventory

    Methylarsonous acid [MMA(III)], a common metabolite of inorganic arsenic metabolism, increases tumor frequency in the skin of K6/ODC transgenic mice following a chronic exposure. To characterize gene expression profiles predictive of MMA(III) exposure and mode of action of carcin...

  5. Free amino acid pool of a sea anemone: exposure and recovery after an oil spill. [Sea Anemones

    SciTech Connect

    Kasschau, M.R.; Howard, C.L.

    1984-07-01

    A number of laboratory studies on marine invertebrates have shown changes in free amino acid (FAA) pools in response to various pollutants. During a nineteen-month field study to determine the effects of natural environmental parameters on the FAA pools to the Gulf Coast sea anemone, Bunodosoma cavernata, an oil tanker collision occurred about 8 miles off Galveston Island. The initial spill from the tanker Burma Agate occurred on November 1, 1979 with large leakages continuing for several weeks. There was no visible sign of oil on the first collection date 13 days after the spill, but 11 days later the anemones were covered with an oil sheen. As a result of this natural exposure to the oil, the authors decided to monitor the sea anemones for changes in the FAA pool during the oil exposure and recovery period.

  6. Acid-based balance and blood gas changes in the fresh water field crab, Barytelphusa guerini, on exposure to organic and inorganic lead

    SciTech Connect

    Tulasi, S.J.; Rao, J.V.R.

    1988-02-01

    The acid-base status of crustacean haemolymph depends on various environmental and physiological factors. Acid base status of the haemolymph is known to be influenced by temperature, salinity, strenuous activity and moulting. The studies on the acid-base regulation of the fresh water crabs are meager. The acid-base changes in fishes during environmental stress conditions like acid stress and zinc toxicity had been reported. But the effect of environmental pollutants like the heavy metals on the acid-base regulation of the fresh water crabs have not been previously reported. The haemolymph of the fresh water crab was found to accumulate high amounts of lead on exposure to organic and inorganic lead. Hence the present investigation has been undertaken to study the haemolymph acid-base status on exposure to subtoxic levels of organic and inorganic lead.

  7. High-time resolution and size-segregated elemental composition in high-intensity pyrotechnic exposures.

    PubMed

    Crespo, Javier; Yubero, Eduardo; Nicolás, Jose F; Lucarelli, Franco; Nava, Silvia; Chiari, Massimo; Calzolai, Giulia

    2012-11-30

    Typical of festivals in Eastern Spain, mascletàs are high-intensity pyrotechnic events where thousands of firecrackers are burnt in an intense, rapid episode that generates short-lived heavy aerosol clouds. High temporal resolution and size distribution characterisation of aerosol components were performed to evaluate the effects of the brief (<30 min) and acute exposure on the spectators present. Very high concentrations of firework specific elements, especially in the fine fraction, were reached during mascletàs, with values of about 500 μg/m(3) for K and 300 μg/m(3) for Cl. Sr, Al, Mg, Ba, Cu, Co, Zn, and Pb concentration increase factors of more than 100 (1000 for Sr and Ba) were observed in the fine fraction with respect to background levels. Crustal origin elements, like Ca, Fe, Si, Ti, also showed an important concentration rise (~10 times above background levels) but this is due to dust resuspension by pyrotechnic explosions. The crustal components are mainly in the coarse mode (>90% elemental mass), between 2 and 3 μm. Most firework related metals are concentrated in the submicrometric region (>80%) with a trimodal size distribution. This may be interesting to epidemiologists given the toxic effects that such fine, metal-rich particles can have on human health. PMID:23026448

  8. Application of MOSFET Detectors for Dosimetry in Small Animal Radiography Using Short Exposure Times

    PubMed Central

    De Lin, Ming; Toncheva, Greta; Nguyen, Giao; Kim, Sangroh; Anderson-Evans, Colin; Johnson, G. Allan; Yoshizumi, Terry T.

    2008-01-01

    Digital subtraction angiography (DSA) X-ray imaging for small animals can be used for functional phenotyping given its ability to capture rapid physiological changes at high spatial and temporal resolution. The higher temporal and spatial requirements for small-animal imaging drive the need for short, high-flux X-ray pulses. However, high doses of ionizing radiation can affect the physiology. The purpose of this study was to verify and apply metal oxide semiconductor field effect transistor (MOSFET) technology to dosimetry for small-animal diagnostic imaging. A tungsten anode X-ray source was used to expose a tissue-equivalent mouse phantom. Dose measurements were made on the phantom surface and interior. The MOSFETs were verified with thermoluminescence dosimeters (TLDs). Bland-Altman analysis showed that the MOSFET results agreed with the TLD results (bias, 0.0625). Using typical small animal DSA scan parameters, the dose ranged from 0.7 to 2.2 cGy. Application of the MOSFETs in the small animal environment provided two main benefits: (1) the availability of results in near real-time instead of the hours needed for TLD processes and (2) the ability to support multiple exposures with different X-ray techniques (various of kVp, mA and ms) using the same MOSFET. This MOSFET technology has proven to be a fast, reliable small animal dosimetry method for DSA imaging and is a good system for dose monitoring for serial and gene expression studies. PMID:18666818

  9. High-time resolution and size-segregated elemental composition in high-intensity pyrotechnic exposures.

    PubMed

    Crespo, Javier; Yubero, Eduardo; Nicolás, Jose F; Lucarelli, Franco; Nava, Silvia; Chiari, Massimo; Calzolai, Giulia

    2012-11-30

    Typical of festivals in Eastern Spain, mascletàs are high-intensity pyrotechnic events where thousands of firecrackers are burnt in an intense, rapid episode that generates short-lived heavy aerosol clouds. High temporal resolution and size distribution characterisation of aerosol components were performed to evaluate the effects of the brief (<30 min) and acute exposure on the spectators present. Very high concentrations of firework specific elements, especially in the fine fraction, were reached during mascletàs, with values of about 500 μg/m(3) for K and 300 μg/m(3) for Cl. Sr, Al, Mg, Ba, Cu, Co, Zn, and Pb concentration increase factors of more than 100 (1000 for Sr and Ba) were observed in the fine fraction with respect to background levels. Crustal origin elements, like Ca, Fe, Si, Ti, also showed an important concentration rise (~10 times above background levels) but this is due to dust resuspension by pyrotechnic explosions. The crustal components are mainly in the coarse mode (>90% elemental mass), between 2 and 3 μm. Most firework related metals are concentrated in the submicrometric region (>80%) with a trimodal size distribution. This may be interesting to epidemiologists given the toxic effects that such fine, metal-rich particles can have on human health.

  10. Application of MOSFET detectors for dosimetry in small animal radiography using short exposure times.

    PubMed

    De Lin, Ming; Toncheva, Greta; Nguyen, Giao; Kim, Sangroh; Anderson-Evans, Colin; Johnson, G Allan; Yoshizumi, Terry T

    2008-08-01

    Digital subtraction angiography (DSA) X-ray imaging for small animals can be used for functional phenotyping given its ability to capture rapid physiological changes at high spatial and temporal resolution. The higher temporal and spatial requirements for small-animal imaging drive the need for short, high-flux X-ray pulses. However, high doses of ionizing radiation can affect the physiology. The purpose of this study was to verify and apply metal oxide semiconductor field effect transistor (MOSFET) technology to dosimetry for small-animal diagnostic imaging. A tungsten anode X-ray source was used to expose a tissue-equivalent mouse phantom. Dose measurements were made on the phantom surface and interior. The MOSFETs were verified with thermoluminescence dosimeters (TLDs). Bland-Altman analysis showed that the MOSFET results agreed with the TLD results (bias, 0.0625). Using typical small animal DSA scan parameters, the dose ranged from 0.7 to 2.2 cGy. Application of the MOSFETs in the small animal environment provided two main benefits: (1) the availability of results in near real-time instead of the hours needed for TLD processes and (2) the ability to support multiple exposures with different X-ray techniques (various of kVp, mA and ms) using the same MOSFET. This MOSFET technology has proven to be a fast, reliable small animal dosimetry method for DSA imaging and is a good system for dose monitoring for serial and gene expression studies. PMID:18666818

  11. Exposure time to hepatitis B virus and associated risk factors among children in Edirne, Turkey.

    PubMed

    Otkun, M; Erdogan, M S; Tatman-Otkun, M; Akata, F

    2005-06-01

    Hepatitis B virus (HBV) infection is endemic in Turkey, but the main routes of transmission were not well established. This study aims to detect the exposure time to HBV and associated risk factors among children. In a sampling group of children aged 0-19 years living in Edirne, antiHBc, antiHBs and HBsAg were screened by the microELISA method. A questionnaire was also completed for each child. In 717 children that were included in the study, the total antiHBc seropositivity was 5.4% and was 1.8, 0.8, 1.7, 6.8, 11.8% in 0-1, 2-5, 6-10, 11-14, 15-19 years age groups respectively. The overall HBsAg seropositivity was 1.7%. The risk of HBV infection increased after the age of 10 years (OR 7.79, 95% CI 3.01-20.16). Collective circumcision was the only independent factor according to regression analysis. Children living in Edirne should be vaccinated against HBV before reaching 11 years of age.

  12. Performance of a 512 x 512 Gated CMOS Imager with a 250 ps Exposure Time

    SciTech Connect

    Teruya, A T; Moody, J D; Hsing, W W; Brown, C G; Griffin, M; Mead, A S; Tran, V

    2012-10-01

    We describe the performance of a 512x512 gated CMOS read out integrated circuit (ROIC) with a 250 ps exposure time. A low-skew, H-tree trigger distribution system is used to locally generate individual pixel gates in each 8x8 neighborhood of the ROIC. The temporal width of the gate is voltage controlled and user selectable via a precision potentiometer. The gating implementation was first validated in optical tests of a 64x64 pixel prototype ROIC developed as a proof-of-concept during the early phases of the development program. The layout of the H-Tree addresses each quadrant of the ROIC independently and admits operation of the ROIC in two modes. If “common mode” triggering is used, the camera provides a single 512x512 image. If independent triggers are used, the camera can provide up to four 256x256 images with a frame separation set by the trigger intervals. The ROIC design includes small (sub-pixel) optical photodiode structures to allow test and characterization of the ROIC using optical sources prior to bump bonding. Reported test results were obtained using short pulse, second harmonic Ti:Sapphire laser systems operating at λ~ 400 nm at sub-ps pulse widths.

  13. Exposure-time based modeling of nonlinear reactive transport in porous media subject to physical and geochemical heterogeneity

    NASA Astrophysics Data System (ADS)

    Sanz-Prat, Alicia; Lu, Chuanhe; Amos, Richard T.; Finkel, Michael; Blowes, David W.; Cirpka, Olaf A.

    2016-09-01

    Transport of reactive solutes in groundwater is affected by physical and chemical heterogeneity of the porous medium, leading to complex spatio-temporal patterns of concentrations and reaction rates. For certain cases of bioreactive transport, it could be shown that the concentrations of reactive constituents in multi-dimensional domains are approximately aligned with isochrones, that is, lines of identical travel time, provided that the chemical properties of the matrix are uniform. We extend this concept to combined physical and chemical heterogeneity by additionally considering the time that a water parcel has been exposed to reactive materials, the so-called exposure time. We simulate bioreactive transport in a one-dimensional domain as function of time and exposure time, rather than space. Subsequently, we map the concentrations to multi-dimensional heterogeneous domains by means of the mean exposure time at each location in the multi-dimensional domain. Differences in travel and exposure time at a given location are accounted for as time difference. This approximation simplifies reactive-transport simulations significantly under conditions of steady-state flow when reactions are restricted to specific locations. It is not expected to be exact in realistic applications because the underlying assumption, such as neglecting transverse mixing altogether, may not hold. We quantify the error introduced by the approximation for the hypothetical case of a two-dimensional, binary aquifer made of highly-permeable, non-reactive and low-permeable, reactive materials releasing dissolved organic matter acting as electron donor for aerobic respiration and denitrification. The kinetically controlled reactions are catalyzed by two non-competitive bacteria populations, enabling microbial growth. Even though the initial biomass concentrations were uniform, the interplay between transport, non-uniform electron-donor supply, and bio-reactions led to distinct spatial patterns of

  14. Exposure-time based modeling of nonlinear reactive transport in porous media subject to physical and geochemical heterogeneity.

    PubMed

    Sanz-Prat, Alicia; Lu, Chuanhe; Amos, Richard T; Finkel, Michael; Blowes, David W; Cirpka, Olaf A

    2016-09-01

    Transport of reactive solutes in groundwater is affected by physical and chemical heterogeneity of the porous medium, leading to complex spatio-temporal patterns of concentrations and reaction rates. For certain cases of bioreactive transport, it could be shown that the concentrations of reactive constituents in multi-dimensional domains are approximately aligned with isochrones, that is, lines of identical travel time, provided that the chemical properties of the matrix are uniform. We extend this concept to combined physical and chemical heterogeneity by additionally considering the time that a water parcel has been exposed to reactive materials, the so-called exposure time. We simulate bioreactive transport in a one-dimensional domain as function of time and exposure time, rather than space. Subsequently, we map the concentrations to multi-dimensional heterogeneous domains by means of the mean exposure time at each location in the multi-dimensional domain. Differences in travel and exposure time at a given location are accounted for as time difference. This approximation simplifies reactive-transport simulations significantly under conditions of steady-state flow when reactions are restricted to specific locations. It is not expected to be exact in realistic applications because the underlying assumption, such as neglecting transverse mixing altogether, may not hold. We quantify the error introduced by the approximation for the hypothetical case of a two-dimensional, binary aquifer made of highly-permeable, non-reactive and low-permeable, reactive materials releasing dissolved organic matter acting as electron donor for aerobic respiration and denitrification. The kinetically controlled reactions are catalyzed by two non-competitive bacteria populations, enabling microbial growth. Even though the initial biomass concentrations were uniform, the interplay between transport, non-uniform electron-donor supply, and bio-reactions led to distinct spatial patterns of

  15. Exposure-time based modeling of nonlinear reactive transport in porous media subject to physical and geochemical heterogeneity.

    PubMed

    Sanz-Prat, Alicia; Lu, Chuanhe; Amos, Richard T; Finkel, Michael; Blowes, David W; Cirpka, Olaf A

    2016-09-01

    Transport of reactive solutes in groundwater is affected by physical and chemical heterogeneity of the porous medium, leading to complex spatio-temporal patterns of concentrations and reaction rates. For certain cases of bioreactive transport, it could be shown that the concentrations of reactive constituents in multi-dimensional domains are approximately aligned with isochrones, that is, lines of identical travel time, provided that the chemical properties of the matrix are uniform. We extend this concept to combined physical and chemical heterogeneity by additionally considering the time that a water parcel has been exposed to reactive materials, the so-called exposure time. We simulate bioreactive transport in a one-dimensional domain as function of time and exposure time, rather than space. Subsequently, we map the concentrations to multi-dimensional heterogeneous domains by means of the mean exposure time at each location in the multi-dimensional domain. Differences in travel and exposure time at a given location are accounted for as time difference. This approximation simplifies reactive-transport simulations significantly under conditions of steady-state flow when reactions are restricted to specific locations. It is not expected to be exact in realistic applications because the underlying assumption, such as neglecting transverse mixing altogether, may not hold. We quantify the error introduced by the approximation for the hypothetical case of a two-dimensional, binary aquifer made of highly-permeable, non-reactive and low-permeable, reactive materials releasing dissolved organic matter acting as electron donor for aerobic respiration and denitrification. The kinetically controlled reactions are catalyzed by two non-competitive bacteria populations, enabling microbial growth. Even though the initial biomass concentrations were uniform, the interplay between transport, non-uniform electron-donor supply, and bio-reactions led to distinct spatial patterns of

  16. The snakehead Channa asiatica accumulates alanine during aerial exposure, but is incapable of sustaining locomotory activities on land through partial amino acid catabolism.

    PubMed

    Chew, Shit F; Wong, Mei Y; Tam, Wai L; Ip, Yuen K

    2003-02-01

    The freshwater snakehead Channa asiatica is an obligatory air-breather that resides in slow-flowing streams and in crevices near riverbanks in Southern China. In its natural habitat, it may encounter bouts of aerial exposure during the dry seasons. In the laboratory, the ammonia excretion rate of C. asiatica exposed to terrestrial conditions in a 12 h:12 h dark:light regime was one quarter that of the submerged control. Consequently, the ammonia contents in the muscle, liver and plasma increased significantly, and C. asiatica was able to tolerate quite high levels of ammonia in its tissues. Urea was not the major product of ammonia detoxification in C. asiatica, which apparently did not possess a functioning ornithine urea cycle. Rather, alanine increased fourfold to 12.6 micromol g(-1) in the muscle after 48 h of aerial exposure. This is the highest level known in adult teleosts exposed to air or an ammonia-loading situation. The accumulated alanine could account for 70% of the deficit in ammonia excretion during this period, indicating that partial amino acid catabolism had occurred. This would allow the utilization of certain amino acids as energy sources and, at the same time, maintain the new steady state levels of ammonia in various tissues, preventing them from rising further. There was a reduction in the aminating activity of glutamate dehydrogenase from the muscle and liver of specimens exposed to terrestrial conditions. Such a phenomenon has not been reported before and could, presumably, facilitate the entry of alpha-ketoglutarate into the Krebs cycle instead of its amination to glutamate, as has been suggested elsewhere. However, in contrast to mudskippers, C. asiatica was apparently unable to reduce the rates of proteolysis and amino acid catabolism, because the reduction in nitrogenous excretion during 48 h of aerial exposure was completely balanced by nitrogenous accumulation in the body. Alanine accumulation also occurred in specimens exposed to

  17. The influence of incubation time, sample preparation and exposure to oxygen on the quality of the MALDI-TOF MS spectrum of anaerobic bacteria.

    PubMed

    Veloo, A C M; Elgersma, P E; Friedrich, A W; Nagy, E; van Winkelhoff, A J

    2014-12-01

    With matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), bacteria can be identified quickly and reliably. This accounts especially for anaerobic bacteria. Because growth rate and oxygen sensitivity differ among anaerobic bacteria, we aimed to study the influence of incubation time, exposure to oxygen and sample preparation on the quality of the spectrum using the Bruker system. Also, reproducibility and inter-examiner variability were determined. Twenty-six anaerobic species, representing 17 genera, were selected based on gram-stain characteristics, growth rate and colony morphology. Inter-examiner variation showed that experience in the preparation of the targets can be a significant variable. The influence of incubation time was determined between 24 and 96 h of incubation. Reliable species identification was obtained after 48 h of incubation for gram-negative anaerobes and after 72 h for gram-positive anaerobes. Exposure of the cultures to oxygen did not influence the results of the MALDI-TOF MS identifications of all tested gram-positive species. Fusobacterium necrophorum and Prevotella intermedia could not be identified after >24 h and 48 h of exposure to oxygen, respectively. Other tested gram-negative bacteria could be identified after 48 h of exposure to oxygen. Most of the tested species could be identified using the direct spotting method. Bifidobacterium longum and Finegoldia magna needed on-target extraction with 70% formic acid in order to obtain reliable species identification and Peptoniphilus ivorii a full extraction. Spectrum quality was influenced by the amount of bacteria spotted on the target, the homogeneity of the smear and the experience of the examiner.

  18. Laser confers less embryo exposure than acid tyrode for embryo biopsy in preimplantation genetic diagnosis cycles: a randomized study

    PubMed Central

    2011-01-01

    We compared two methods of zona pellucida drilling. 213 embryos were biopsied with acid Tyrode. Each biopsy took 3 minutes and the entire procedure ~29 minutes. 5% of blastomeres lysed, 49% of embryos became blastocyst and 36% of patients became pregnant. 229 embryos were biopsied with laser. Each biopsy took 30 seconds and the entire procedure ~7 minutes. 2.5% of blastomeres lysed, 50.6% of embryos became blastocyst and 47% of patients became pregnant. We can conclude that laser can be used for embryo biopsy. Reduction of embryo exposure and of removed blastomeres is associated with increased blastocysts available for transfer and a better clinical outcome. PMID:21527004

  19. Time dependent inhibition of xanthine oxidase in irradiated solutions of folic acid, aminopterin and methotrexate

    SciTech Connect

    Robinson, K.; Pilot, T.F.; Meany, J.E. )

    1990-01-01

    The xanthine oxidase catalyzed oxidation of hypoxanthine was followed by monitoring the formation of uric acid at 290 nm. Inhibition of xanthine oxidase occurs in aqueous solutions of folic acid methotrexate and aminopterin. These compounds are known to dissociate upon exposure to ultraviolet light resulting in the formation of their respective 6-formylpteridine derivatives. The relative rates of dissociation were monitored spectrophotometrically by determining the absorbance of their 2,4-dinitrophenylhydrazine derivatives at 500 nm. When aqueous solutions of folic acid, aminopterin and methotrexate were exposed to uv light, a direct correlation was observed between the concentrations of the 6-formylpteridine derivatives existing in solution and the ability of these solutions to inhibit xanthine oxidase. The relative potency of the respective photolysis products were estimated.

  20. The interaction between humic acid and naphthalene after exposure to visible and UV light

    NASA Astrophysics Data System (ADS)

    Nechaev, L. V.; Tchaikovskaya, O. N.

    2015-12-01

    Dissolved organic matter plays an important role in pollution migration from human waste to aquatic environments. In this study, the effect of humic acid (HA) on the photo-chemical transformation of naphthalene by irradiation model solar and UV light was reported using fluorescence quenching titrations. It was calculated the interactions between naphthalene and humic acids. It is found that the molecular complex of humic acid and naphthalene is more stable to UV irradiation, compared with the model solar radiation. The application of molecular fluorescence spectrometry is a useful sensitive tool evaluate intermolecular HA and naphthalene interactions.

  1. Diesel engine exhaust and lung cancer mortality: time-related factors in exposure and risk.

    PubMed

    Moolgavkar, Suresh H; Chang, Ellen T; Luebeck, Georg; Lau, Edmund C; Watson, Heather N; Crump, Kenny S; Boffetta, Paolo; McClellan, Roger

    2015-04-01

    To develop a quantitative exposure-response relationship between concentrations and durations of inhaled diesel engine exhaust (DEE) and increases in lung cancer risks, we examined the role of temporal factors in modifying the estimated effects of exposure to DEE on lung cancer mortality and characterized risk by mine type in the Diesel Exhaust in Miners Study (DEMS) cohort, which followed 12,315 workers through December 1997. We analyzed the data using parametric functions based on concepts of multistage carcinogenesis to directly estimate the hazard functions associated with estimated exposure to a surrogate marker of DEE, respirable elemental carbon (REC). The REC-associated risk of lung cancer mortality in DEMS is driven by increased risk in only one of four mine types (limestone), with statistically significant heterogeneity by mine type and no significant exposure-response relationship after removal of the limestone mine workers. Temporal factors, such as duration of exposure, play an important role in determining the risk of lung cancer mortality following exposure to REC, and the relative risk declines after exposure to REC stops. There is evidence of effect modification of risk by attained age. The modifying impact of temporal factors and effect modification by age should be addressed in any quantitative risk assessment (QRA) of DEE. Until there is a better understanding of why the risk appears to be confined to a single mine type, data from DEMS cannot reliably be used for QRA.

  2. Urinary Tetrabromobenzoic Acid (TBBA) as a Biomarker of Exposure to the Flame Retardant Mixture Firemaster® 550

    PubMed Central

    Hoffman, Kate; Fang, Mingliang; Horman, Brian; Patisaul, Heather B.; Garantziotis, Stavros; Birnbaum, Linda S.

    2014-01-01

    Background: Firemaster® 550 (FM550) is commonly added to residential furniture to reduce its flammability. Recent toxicological evidence suggests that FM550 may be endocrine disrupting and obesogenic. Objectives: Our objectives were to develop methods to assess exposure to FM550 in human populations and to identify potential routes of exposure. Methods: Using mass spectrometry methods, we developed a method to measure 2,3,4,5-tetrabromobenzoic acid (TBBA), a urinary metabolite of the major brominated FM550 component 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (TBB). The method was applied to a cohort of adult volunteers (n = 64). Participants completed questionnaires, provided urine and handwipe samples, and collected dust samples from their homes. We measured TBB and the other major brominated FM550 component, bis(2-ethylhexyl)-2,3,4,5-tetrabromophthalate (TBPH), in paired dust and handwipe samples. Results: TBBA was detected in 72.4% of urine samples. Although TBBA is a rapidly formed metabolite, analyses indicated moderate temporal reliability (interclass correlation coefficient = 0.56; 95% confidence interval: 0.46, 0.66). TBB and TBPH were detected frequently in dust samples [geometric mean (GM) = 315.1 and 364.7 ng/g, respectively] and in handwipes (GM = 31.4 and 23.4 ng, respectively). Levels of TBB and TBPH in dust were positively correlated with levels in handwipes. In addition, levels of TBB in handwipes were positively correlated with urinary TBBA. Results suggest frequent hand washing may reduce the mass of TBB on participants’ hands and reduce urinary TBBA levels. Conclusions: Cumulatively, our data indicate that exposures to FM550 are widespread and that the home environment may be an important source of exposure. Urinary TBBA provides a potentially useful biomarker of FM550 exposure for epidemiologic studies. Citation: Hoffman K, Fang M, Horman B, Patisaul HB, Garantziotis S, Birnbaum LS, Stapleton HM. 2014. Urinary tetrabromobenzoic acid (TBBA) as a

  3. Motoneuron axon pathfinding errors in zebrafish: Differential effects related to concentration and timing of nicotine exposure

    SciTech Connect

    Menelaou, Evdokia; Paul, Latoya T.; Perera, Surangi N.; Svoboda, Kurt R.

    2015-04-01

    Nicotine exposure during embryonic stages of development can affect many neurodevelopmental processes. In the developing zebrafish, exposure to nicotine was reported to cause axonal pathfinding errors in the later born secondary motoneurons (SMNs). These alterations in SMN axon morphology coincided with muscle degeneration at high nicotine concentrations (15–30 μM). Previous work showed that the paralytic mutant zebrafish known as sofa potato exhibited nicotine-induced effects onto SMN axons at these high concentrations but in the absence of any muscle deficits, indicating that pathfinding errors could occur independent of muscle effects. In this study, we used varying concentrations of nicotine at different developmental windows of exposure to specifically isolate its effects onto subpopulations of motoneuron axons. We found that nicotine exposure can affect SMN axon morphology in a dose-dependent manner. At low concentrations of nicotine, SMN axons exhibited pathfinding errors, in the absence of any nicotine-induced muscle abnormalities. Moreover, the nicotine exposure paradigms used affected the 3 subpopulations of SMN axons differently, but the dorsal projecting SMN axons were primarily affected. We then identified morphologically distinct pathfinding errors that best described the nicotine-induced effects on dorsal projecting SMN axons. To test whether SMN pathfinding was potentially influenced by alterations in the early born primary motoneuron (PMN), we performed dual labeling studies, where both PMN and SMN axons were simultaneously labeled with antibodies. We show that only a subset of the SMN axon pathfinding errors coincided with abnormal PMN axonal targeting in nicotine-exposed zebrafish. We conclude that nicotine exposure can exert differential effects depending on the levels of nicotine and developmental exposure window. - Highlights: • Embryonic nicotine exposure can specifically affect secondary motoneuron axons in a dose-dependent manner.

  4. Effect of citric acid concentration and hydrolysis time on physicochemical properties of sweet potato starches.

    PubMed

    Surendra Babu, Ayenampudi; Parimalavalli, Ramanathan; Rudra, Shalini Gaur

    2015-09-01

    Physicochemical properties of citric acid treated sweet potato starches were investigated in the present study. Sweet potato starch was hydrolyzed using citric acid with different concentrations (1 and 5%) and time periods (1 and 11 h) at 45 °C and was denoted as citric acid treated starch (CTS1 to CTS4) based on their experimental conditions. The recovery yield of acid treated starches was above 85%. The CTS4 sample displayed the highest amylose (around 31%) and water holding capacity its melting temperature was 47.66 °C. The digestibility rate was slightly increased for 78.58% for the CTS3 and CTS4. The gel strength of acid modified starches ranged from 0.27 kg to 1.11 kg. RVA results of acid thinned starches confirmed a low viscosity profile. CTS3 starch illustrated lower enthalpy compared to all other modified starches. All starch samples exhibited a shear-thinning behavior. SEM analysis revealed that the extent of visible degradation was increased at higher hydrolysis time and acid concentration. The CTS3 satisfied the criteria required for starch to act as a fat mimetic. Overall results conveyed that the citric acid treatment of sweet potato starch with 5% acid concentration and 11h period was an ideal condition for the preparation of a fat replacer.

  5. The efficacy of protoporphyrin as a predictive biomarker for lead exposure in canvasback ducks: effect of sample storage time

    USGS Publications Warehouse

    Franson, J.C.; Hohman, W.L.; Moore, J.L.; Smith, M.R.

    1996-01-01

    We used 363 blood samples collected from wild canvasback ducks (Aythya valisineria) at Catahoula Lake, Louisiana, U.S.A. to evaluate the effect of sample storage time on the efficacy of erythrocytic protoporphyrin as an indicator of lead exposure. The protoporphyrin concentration of each sample was determined by hematofluorometry within 5 min of blood collection and after refrigeration at 4 °C for 24 and 48 h. All samples were analyzed for lead by atomic absorption spectrophotometry. Based on a blood lead concentration of ≥0.2 ppm wet weight as positive evidence for lead exposure, the protoporphyrin technique resulted in overall error rates of 29%, 20%, and 19% and false negative error rates of 47%, 29% and 25% when hematofluorometric determinations were made on blood at 5 min, 24 h, and 48 h, respectively. False positive error rates were less than 10% for all three measurement times. The accuracy of the 24-h erythrocytic protoporphyrin classification of blood samples as positive or negative for lead exposure was significantly greater than the 5-min classification, but no improvement in accuracy was gained when samples were tested at 48 h. The false negative errors were probably due, at least in part, to the lag time between lead exposure and the increase of blood protoporphyrin concentrations. False negatives resulted in an underestimation of the true number of canvasbacks exposed to lead, indicating that hematofluorometry provides a conservative estimate of lead exposure.

  6. PROSTATE CANCER: IS IT TIME TO EXPAND THE RESEARCH FOCUS TO EARLY-LIFE EXPOSURES?

    PubMed Central

    Sutcliffe, Siobhan; Colditz, Graham A.

    2013-01-01

    Preface Although the contribution of lifestyle and environment (non-genetic factors) to prostate carcinogenesis is indicated by international variation in prostate cancer occurrence and migration studies, no conclusive modifiable risk factors have been identified to date. One possible reason for this may be the dearth of epidemiological research on exposures experienced early-in-life when the immature prostate may be more susceptible to carcinogenic exposures. Herein, we motivate the study of early-life exposures, describe the small body of early-life research and its associated challenges, and point towards solutions for future research. PMID:23363989

  7. Balancing the benefits of n-3 polyunsaturated fatty acids and the risks of methylmercury exposure from fish consumption

    PubMed Central

    Mahaffey, Kathryn R; Sunderland, Elsie M; Chan, Hing Man; Choi, Anna L; Grandjean, Philippe; Mariën, Koenraad; Oken, Emily; Sakamoto, Mineshi; Schoeny, Rita; Weihe, Pál; Yan, Chong-Huai; Yasutake, Akira

    2011-01-01

    Fish and shellfish are widely available foods that provide important nutrients, particularly n-3 polyunsaturated fatty acids (n-3 PUFAs), to many populations globally. These nutrients, especially docosahexaenoic acid, confer benefits to brain and visual system development in infants and reduce risks of certain forms of heart disease in adults. However, fish and shellfish can also be a major source of methylmercury (MeHg), a known neurotoxicant that is particularly harmful to fetal brain development. This review documents the latest knowledge on the risks and benefits of seafood consumption for perinatal development of infants. It is possible to choose fish species that are both high in n-3 PUFAs and low in MeHg. A framework for providing dietary advice for women of childbearing age on how to maximize the dietary intake of n-3 PUFAs while minimizing MeHg exposures is suggested. PMID:21884130

  8. Specific time of exposure during tadpole development influences biological effects of the insecticide carbaryl in green frogs (Lithobates clamitans).

    PubMed

    Boone, Michelle D; Hammond, S Austin; Veldhoen, Nik; Youngquist, Melissa; Helbing, Caren C

    2013-04-15

    The orchestration of anuran metamorphosis is initiated and integrated by thyroid hormones, which change dynami