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...

Permethrin exposure from fabric-treated military uniforms under different wear-time scenarios.

PubMed

Proctor, Susan P; Maule, Alexis L; Heaton, Kristin J; Adam, Gina E

2014-11-01

The objective of the project was to ascertain whether urinary biomarkers of permethrin exposure are detected after wearing post-tailored, fabric-treated military uniforms under two different wear-time exposure scenarios. Study A occurred over 3.5 days and involved six participants wearing treated uniforms continuously for 30-32 h. Urine collection occurred at scheduled time points before, during, and after wearing the uniform. Study B, conducted over 19 days, included 11 participants wearing treated uniforms for 3 consecutive days, 8 h each day (with urine collection before, during, and after wear). Urinary biomarkers of permethrin (3-phenoxybenzoic acid (3PBA), cis- 2,2-(dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (cDCCA), trans- 2,2-(dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (tDCCA)) were detected during and after wear. Biomarker detection generally occurred over the 10- to 12-h period after putting on the uniform and subsided 24 h following uniform removal (in both Study A and B scenarios). Those wearing permethrin-treated uniforms under the longer wear-time scenario (Study A) excreted significantly higher cumulative mean levels compared with those in Study B (3.29 times higher for 3PBA and 2.23 times higher for the sum of c/tDCCA (P≤0.001)). Findings suggest that wearing permethrin-treated clothing does increase absorbed, internal dose levels of permethrin above population levels and is significantly related to wear-time duration.

Influence of post exposure bake time on EUV photoresist RLS trade-off

NASA Astrophysics Data System (ADS)

Vesters, Yannick; De Simone, Danilo; De Gendt, Stefan

2017-03-01

To achieve high volume manufacturing, EUV photoresists need to push back the "RLS trade-off" by simultaneously improving Resolution, Line-Width Roughness and Sensitivity (exposure dose). Acid diffusion in chemically amplified resist is known to impact these performances. This work studies the diffusion of acid in chemically amplified resist by varying the post exposure bake duration while monitoring the evolution of CD and LWR for 6 chemically amplified EUV photoresists (CAR). We observed a first regime where both CD and LWR quickly decrease during the first 30s of post exposure bake (PEB). This can be related to the deprotection reaction taking place in the exposed part of the resist. After 60s the decrease in CD and LWR slows down significantly, likely related to a regime of acid diffusion from exposed to unexposed region, and acid-quencher neutralization at the interface of these two regions. We tested two resists with different protecting group and the one having lower activation energy shows a faster CD change in the second regime, resulting in a worsening of LWR for longer PEB time. On the contrary, a resist with a high quencher loading shows reduced net diffusion of acid towards the unexposed region and controls the resist edge profile. In other words longer PEB does not degrade LWR, but as it reduces the line CD, sensitivity is impacted. With an appropriate ratio selection of quencher to PAG, an EUV dose reduction of up to 12% can be achieved with a change from a standard 60 second to a 240 second PEB time, while keeping LWR and resolution constant and therefore pushing the RLS performances. Finally, we confirmed that the observations on positive tone development (PTD) resist could be applied to negative tone development (NTD) resist: with a high quencher NTD resist we observed a dose reduction of 8% for longer PEB time, keeping LWR and resolution constant.

Incidence of laryngeal cancer and exposure to acid mists.

PubMed Central

Steenland, K; Schnorr, T; Beaumont, J; Halperin, W; Bloom, T

1988-01-01

To determine the relation between exposure to acid mist and laryngeal cancer, the smoking habits, drinking habits, and incidence of laryngeal cancer of 879 male steelworkers exposed to acid mists during pickling operations was ascertained. Sulphuric acid mist was the primary exposure for most men in this cohort. These men had all worked in a pickling operation for a minimum of six months before 1965, with an average duration of exposure of 9.5 years. Exposures to sulphuric acid in the 1970s averaged about 0.2 mg/m3, and earlier exposures were probably similar. Interviews were conducted with all cohort members or their next of kin in 1986 and medical records of decedents were reviewed. Nine workers were identified who had been diagnosed as having laryngeal cancer, using a conservative case definition that required medical record confirmation for any case among decedents and confirmation by a physician for any case among live individuals. Using data from national surveys of cancer incidence as referent rates, 3.44 laryngeal cancers would have been expected. Excess smoking by the exposed cohort compared with the United States population resulted in an upward adjustment of the expected number of cases of laryngeal cancer to 3.92. The standardised incidence rate ratio for laryngeal cancer was 2.30 (9/3.92), with a one sided p value of 0.01 (assuming a Poisson distribution). The finding of excess laryngeal cancer in this cohort is consistent with four other studies published since 1981. PMID:3203082

Esophageal manometry findings and degree of acid exposure in short and long Barrett's esophagus.

PubMed

Helman, Laura; Biccas, Beatriz Nunes; Lemme, Eponina M O; Novais, Paula; Fittipaldi, Viviane

2012-01-01

Barrett's esophagus (BE) is characterized by intestinal metaplasia in the distal esophagus and is classified as short-segment (<3 cm - SSBE) or long-segment (>3 cm - LSSBE). It is suggested that LSSBE is associated with more severe esophageal motor abnormalities and increased acid exposure time than SSBE. To evaluate the prevalence of esophageal manometriy abnormalities and acid exposure times in patients with SSBE and LSSBE. Barrett's esophagus patients identified by upper endoscopy and confirmed by histopathology were, retrospectively, reviewed and divided into two groups: SSBE and LSBE. Demographic data, symptom duration, prevalence of hiatal hernia, lower esophagus sphincter basal pressure, prevalence of esophageal body abnormalities and acid exposure times were evaluated. Forty-six patients with SSBE (24 males - 52.2%, mean age of 55.2 years) and 28 patients with LSBE (18 males - 64.3%, mean age of 50.5 years). Mean symptom duration was 9.9 years for SSBE and 12.9 years for LSSBE. Hiatal hernia was present in 84.2% of SSBE, 96.3% of LSBE; average lower esophagus sphincter pressure in SSBE 9.15 mm Hg, in LSBE 6.99 mm Hg; lower esophagus sphincter hypotension in SSBE was 65.9%, in LSSBE 82.1%; aperistalsis in SSBE 6.5%, LSSBE 3.6%; mild/moderate ineffective esophageal motility in SSBE 34.8%, LSBE 46.4%; severe moderate ineffective esophageal motility in SSBE 10.9%, LSBE 7,1%; nutcracker esophagus/segmental nutcracker esophagus in SSBE 8.6%, LSBE 0%; normal body in SSBE 39.1%, in LSBE 42.9%, no statistical difference for any of these values (P<0.05). Average % total time pH<4 in SSBE 9.12, LSBE 17.27 (P<0.000); % time pH<4 upright in SSBE 11.91; LSBE 24.29 (P=0.003); % time pH<4 supine in SSBE 10.86, LSBE 33.26 (P = 0.000). There was no difference between the prevalence of motor disorders in patients with SSBE and LSSBE. Acid reflux in upright and supine positions was more intense in LSBE.

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

Understanding potential exposure sources of perfluorinated carboxylic acids in the workplace.

PubMed

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

2010-11-01

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.

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 ...

The effect of lead exposure on fatty acid composition in mouse brain analyzed using pseudo-catalytic derivatization.

PubMed

Jung, Jong-Min; Lee, Jechan; Kim, Ki-Hyun; Jang, In Geon; Song, Jae Gwang; Kang, Kyeongjin; Tack, Filip M G; Oh, Jeong-Ik; Kwon, Eilhann E; Kim, Hyung-Wook

2017-03-01

We performed toxicological study of mice exposed to lead by quantifying fatty acids in brain of the mice. This study suggests that the introduced analytical method had an extremely high tolerance against impurities such as water and extractives; thus, it led to the enhanced resolution in visualizing the spectrum of fatty acid profiles in animal brain. Furthermore, one of the biggest technical advantages achieved in this study was the quantitation of fatty acid methyl ester profiles of mouse brain using a trace amount of sample (e.g., 100 μL mixture). Methanol was screened as the most effective extraction solvent for mouse brain. The behavioral test of the mice before and after lead exposure was conducted to see the effect of lead exposure on fatty acid composition of the mice' brain. The lead exposure led to changes in disease-related behavior of the mice. Also, the lead exposure induced significant alterations of fatty acid profile (C16:0, C 18:0, and C 18:1) in brain of the mice, implicated in pathology of psychiatric diseases. The alteration of fatty acid profile of brain of the mice suggests that the derivatizing technique can be applicable to most research fields associated with the environmental neurotoxins with better resolution in a short time, as compared to the current protocols for lipid analysis. Copyright © 2016 Elsevier Ltd. All rights reserved.

Persistent behavioral effects following early life exposure to retinoic acid or valproic acid in zebrafish

PubMed Central

Bailey, Jordan M.; Oliveri, Anthony N.; Karbhari, Nishika; Brooks, Roy A.J.; De La Rocha, Amberlene J.; Janardhan, Sheila; Levin, Edward D.

2015-01-01

BACKGROUND Moderate to severe dysregulation in retinoid signaling during early development is associated with a constellation of physical malformations and/or neural tube defects, including spina bifida. It is thought that more subtle dysregulation of this system, which might be achievable via dietary (i.e. hypervitaminosis A) or pharmacological (i.e. valproic acid) exposure in humans, will manifest on behavioral domains including sociability, without overt physical abnormalities. METHODS During early life, zebrafish were exposed to low doses of two chemicals that disrupt retinoid signaling. From 0-5 dpf, larvae were reared in aqueous solutions containing retinoic acid (0, 0.02, 0.2 or 2 nM) or valproic acid (0, 0.5, 5.0 or 50 uM). One cohort of zebrafish was assessed using a locomotor activity screen at 6-dpf; another was reared to adulthood and assessed using a neurobehavioral test battery (startle habituation, novel tank exploration, shoaling, and predator escape/avoidance). RESULTS There was no significant increase in the incidence of physical malformation among exposed fish compared to controls. Both retinoic acid and valproic acid exposures during development disrupted larval activity with persisting behavioral alterations later in life, primarily manifesting as decreased social affiliation. CONCLUSIONS Social behavior and some aspects of motor function were altered in exposed fish; the importance of examining emotional or psychological consequences of early life exposure to retinoid acting chemicals is discussed. PMID:26439099

Distal esophageal hypercontractility is related to abnormal acid exposure.

PubMed

Soto-Pérez, Julio César; Sobrino-Cossío, Sergio; Higgins, Paul B; Comuzzie, Anthony G; Vargas Romero, Jose Antonio; Reding-Bernal, Arturo; López-Alvarenga, Juan Carlos

2011-02-01

Nutcracker esophagus (NE) is a frequent primary motility disorder of the distal esophagus, and the relationship with acid exposure remains controversial. We studied simultaneous distal esophageal hypercontractility (EH) using two sensors at 8 and 3 cm above the lower sphincter (LES) and abnormal exposure to acid (pH DeMeester score). From 400 screened patients with chest pain and heartburn, 54 (age 44.5 ± 8.8 years and 74% females) had abnormal manometry and underwent acid exposure measurement. Frequencies of the EH disorder were classic NE (EH(3 cm)) found in 29 (40.8%) patients, diffuse (EH(3,8 cm)) in 30 patients (42.3%), and upper segmental (EH(8 cm)) in 12 patients (16.9%). We found a positive correlation among age with high amplitude in EH(3 cm) and EH(3,8 cm). DeMeester's score (DMS) had the lowest value for EH(3,8 cm) (2.58 ± 0.23) compared with EH(8 cm) (3.78 ± 0.3, p <0.003) and EH(3 cm) (3.12 ± 0.2, p <0.06). Surface response for joint effect of age and DMS on amplitude at EH(3 cm) confirmed the highest amplitude was for older age and lower DMS. EH(3 cm) and EH(3,8 cm) were common for esophageal motility and were inversely associated with DMS. Meanwhile, acid exposure was higher in younger patients and hypercontractility was more frequent in older subjects. The former group may benefit more from proton pump inhibitors and the latter from visceral analgesics or possibly both. Copyright © 2011 IMSS. Published by Elsevier Inc. All rights reserved.

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. © 2014 International Society for Diseases of the Esophagus.

Global metabolomic profiling reveals an association of metal fume exposure and plasma unsaturated fatty acids.

PubMed

Wei, Yongyue; Wang, Zhaoxi; Chang, Chiung-yu; Fan, Tianteng; Su, Li; Chen, Feng; Christiani, David C

2013-01-01

Welding-associated air pollutants negatively affect the health of exposed workers; however, their molecular mechanisms in causing disease remain largely unclear. Few studies have systematically investigated the systemic toxic effects of welding fumes on humans. To explore the effects of welding fumes on the plasma metabolome, and to identify biomarkers for risk assessment of welding fume exposure. The two-stage, self-controlled exploratory study included 11 boilermakers from a 2011 discovery panel and 8 boilermakers from a 2012 validation panel. Plasma samples were collected pre- and post-welding fume exposure and analyzed by chromatography/mass spectrometry. Eicosapentaenoic or docosapentaenoic acid metabolic changes post-welding were significantly associated with particulate (PM2.5) exposure (p<0.05). The combined analysis by linear mixed-effects model showed that exposure was associated with a statistically significant decline in metabolite change of eicosapentaenoic acid [β(95% CI) = -0.013(-0.022 ≈ -0.004); p = 0.005], docosapentaenoic acid n3 [β(95% CI) = -0.010(-0.018 ≈ -0.002); p = 0.017], and docosapentaenoic acid n6 [β(95% CI) = -0.007(-0.013 ≈ -0.001); p = 0.021]. Pathway analysis identified an association of the unsaturated fatty acid pathway with exposure (p Study-2011 = 0.025; p Study-2012 = 0.021; p Combined = 0.009). The functional network built by these fatty acids and their interactive genes contained significant enrichment of genes associated with various diseases, including neoplasms, cardiovascular diseases, and lipid metabolism disorders. High-dose exposure of metal welding fumes decreases unsaturated fatty acids with an exposure-response relationship. This alteration in fatty acids is a potential biological mediator and biomarker for exposure-related health disorders.

Global Metabolomic Profiling Reveals an Association of Metal Fume Exposure and Plasma Unsaturated Fatty Acids

PubMed Central

Chang, Chiung-yu; Fan, Tianteng; Su, Li; Chen, Feng; Christiani, David C.

2013-01-01

Background Welding-associated air pollutants negatively affect the health of exposed workers; however, their molecular mechanisms in causing disease remain largely unclear. Few studies have systematically investigated the systemic toxic effects of welding fumes on humans. Objectives To explore the effects of welding fumes on the plasma metabolome, and to identify biomarkers for risk assessment of welding fume exposure. Methods The two-stage, self-controlled exploratory study included 11 boilermakers from a 2011 discovery panel and 8 boilermakers from a 2012 validation panel. Plasma samples were collected pre- and post-welding fume exposure and analyzed by chromatography/mass spectrometry. Results Eicosapentaenoic or docosapentaenoic acid metabolic changes post-welding were significantly associated with particulate (PM2.5) exposure (p<0.05). The combined analysis by linear mixed-effects model showed that exposure was associated with a statistically significant decline in metabolite change of eicosapentaenoic acid [(95% CI) = −0.013(−0.022∼−0.004); p = 0.005], docosapentaenoic acid n3 [(95% CI) = −0.010(−0.018∼−0.002); p = 0.017], and docosapentaenoic acid n6 [(95% CI) = −0.007(−0.013∼−0.001); p = 0.021]. Pathway analysis identified an association of the unsaturated fatty acid pathway with exposure (p Study−2011 = 0.025; p Study−2012 = 0.021; p Combined = 0.009). The functional network built by these fatty acids and their interactive genes contained significant enrichment of genes associated with various diseases, including neoplasms, cardiovascular diseases, and lipid metabolism disorders. Conclusions High-dose exposure of metal welding fumes decreases unsaturated fatty acids with an exposure-response relationship. This alteration in fatty acids is a potential biological mediator and biomarker for exposure-related health disorders. PMID:24143234

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

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.

Perfluorooctanoic Acid Exposure and Pregnancy Outcome in a Highly Exposed Community

PubMed Central

Savitz, David A.; Stein, Cheryl R.; Bartell, Scott M.; Elston, Beth; Gong, Jian; Shin, Hyeong-Moo; Wellenius, Gregory A.

2012-01-01

Background We assessed the association between perfluorooctanoic acid (PFOA) and pregnancy outcome in an area with elevated exposure to PFOA from drinking water contaminated by chemical plant releases. Methods Serum PFOA was measured and reproductive and residential histories were obtained in 2005 – 2006. We estimated serum PFOA levels at the time of pregnancy for 11,737 pregnancies occurring between 1990 and 2006 based on historical information on PFOA releases, environmental distribution, pharmacokinetic modeling, and residential histories. We assessed the association between PFOA and the odds of miscarriage, stillbirth, preeclampsia, preterm birth, term low birthweight, and birth defects controlling for calendar time, age, parity, education, and smoking. PFOA exposure was evaluated as a continuous measure (with and without log-transformation) and in quintiles, combining the lowest two quintiles (<6.8 ng/mL) as the referent. Results Measures of association between PFOA and miscarriage, preterm birth, term low birthweight, and birth defects were close to the null. Odds of stillbirth were elevated in the 4th quintile only. For preeclampsia, the odds ratio was 1.13 (95% confidence interval = 1.00 – 1.28) for an interquartile shift in log-transformed PFOA, and the odds ratios were 1.1 – 1.2 across the upper three quintiles of exposure. Conclusions In this large, population-based study in a region with markedly elevated PFOA exposure, we found no associations between estimated serum PFOA levels and adverse pregnancy outcomes other than possibly preeclampsia. Conclusions are tempered by inherent limitations in exposure reconstruction and self-reported pregnancy outcome information. PMID:22370857

Latent carcinogenicity of early-life exposure to dichloroacetic acid in mice

EPA Science Inventory

AbstractEnvironmental exposures occurring early in life may have an important influence on cancer risk later in life. Here we investigated carryover effects of young-adult exposure to dichloroacetic acid (DCA), a small molecule analog of pyruvate and low-level environmental cont...

Growth and physiological responses of beech seedlings to long-term exposure of acid fog.

PubMed

Shigihara, Ado; Matsumoto, Kiyoshi; Sakurai, Naoki; Igawa, Manabu

2008-02-25

Seven-year-old beech seedlings (Fagus crenata) were exposed to simulated acid fog (SAF) at pH 3 or pH 5 (as control) prepared by adding a 2:1:1 mixture (molar ratio) of nitric acid, ammonium sulfate, and sodium chloride to ultrapure water from September 2004 to July 2006 in a mobile fog chamber. In comparison to control seedlings, seedlings from the pH 3 treatment displayed inferior plant height, stem diameter, number of leaves, and dry matter production, but greater leaf area. Furthermore, exposure to SAF induced early falling of leaves with a nearly two-times-greater normalized leaf number index than control. The starch levels in the stems of seedlings of the pH 3 treatment were much lower than those of control at the harvest. The acid fog-induced reduction of the starch accumulation is considered to occur mainly because of fewer leaves during the growth phase. Results of laboratory experiments demonstrate that the amount of base cations leached from the beech leaves increased with decreasing pH of SAF; the leaching amount of calcium ion from the beech was high relative to that of conifers such as fir and cedar. These results imply that chronic acid fog exposure suppresses growth and physiological activity of beech seedlings.

[Examination of laser-treated tooth surfaces after exposure to acid].

PubMed

Beeking, P O; Herrmann, C; Zuhrt, R

1990-12-01

In principle it is possible to homogenize the enamel surface by melting structural elements with the continuous wave CO2 laser. An experimental caries model was used for testing the acid resistance of the laser exposed tooth surfaces. Laser-treatment and measured exposure to acid produced zones of homogeneous smelting with microcracks and disintegration symptoms. Underneath the melted region the heat leakage obviously causes photo-thermic++ effects determined by increased resistance to acid.

Effects of omeprazole or anti-reflux surgery on lower oesophageal sphincter characteristics and oesophageal acid exposure over 10 years.

PubMed

Emken, Birgitte-Elise G; Lundell, Lars R; Wallin, Lene; Myrvold, Helge E; Engström, Cecilia; Montgomery, Madeleine; Malm, Anders R; Lind, Tore; Hatlebakk, Jan G

2017-01-01

To compare the effect of anti-reflux surgery (ARS) versus proton pump inhibitor therapy on lower oesophageal sphincter (LOS) function and oesophageal acid exposure in patients with chronic gastro-oesophageal reflux disease (GORD) over a decade of follow-up. In this randomised, prospective, multicentre study we compared LOS pressure profiles, as well as oesophageal exposure to acid, at baseline and at 1 and 10 years after randomisation to either open ARS (n = 137) or long-term treatment with omeprazole (OME) 20-60 mg daily (n = 108). Median LOS resting pressure and abdominal length increased significantly and remained elevated in patients operated on with ARS, as opposed to those on OME. The proportion of total time (%) with oesophageal pH <4.0 decreased significantly in both the surgical and medical groups, and was significantly lower after 1 year in patients treated with ARS versus OME. After 10 years, oesophageal acid exposure was normalised in both groups, with no significant differences, and bilirubin exposure was within normal limits. After 10 years, patients with or without Barrett's oesophagus did not differ in acid reflux control between the two treatment options. Open ARS and OME were both effective in normalising acid reflux into the oesophagus even when studied over a period of 10 years. Anatomically and functionally the LOS was repaired durably by surgery, with increased resting pressure and abdominal length.

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

Influence of exposure time on toxicity-An overview.

PubMed

Connell, Des W; Yu, Qiming J; Verma, Vibha

2016-04-29

Data on toxicity of chemicals is usually reported as the LD50, or LC50, with the exposure time from experimental testing in the laboratory reported. But the exposure time is not considered to be a quantifiable variable which can be used to evaluate its importance in expressed toxicity, often described in general terms such as acute, chronic and so on. For the last hundred years Habers Rule has been successfully used to extrapolate from reported exposure times to other exposure times which may be needed for setting standards, health risk assessments and other applications. But it has limitations particularly in environmental applications where exposure levels are low and exposure times are relatively long. The Reduced Life Expectancy (RLE) model overcomes these problems and can be utilised under all exposure conditions. It can be expressed as ln(LT50)=-a (LC50)(ν)+b where the constants ν, a and b can be evaluated by fitting the model to experimental data on the LC50, and corresponding LT50, together with the Normal Life Expectancy (NLE) of the organism being considered as a data point when the LC50 is zero. The constant, ν, at a value of unity gives a linear relationship and where ν<1 the relationship has a concave shape. In our extensive evaluations of the RLE model for fish, invertebrates and mammals involving 115 data sets and with a wide range of organic and inorganic toxicants the RLE model gave correlation coefficients of >0.8 with 107 sets of data. The RLE model can be used to extrapolate from a limited data set on exposure times and corresponding LT50 values to any exposure time and corresponding LT50 value. The discrepancy between Haber's Rule and RLE model increases as the exposure time increases. Copyright © 2016 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

Exposure Time Optimization for Highly Dynamic Star Trackers

PubMed Central

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

2014-01-01

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. PMID:24618776

Case-control study: soft-tissue sarcomas and exposure to phenoxyacetic acids or chlorophenols.

PubMed Central

Hardell, L.; Sandström, A.

1979-01-01

In 1977 a number of patients with soft-tissue sarcomas and previous exposure to phenoxyacetic acids were described. Following from these observations a matched case-control study was made. Exposure to chlorophenols was also included in this study. The results showed that exposure to phenoxyacetic acids or chlorophenols gave an approximately 6-fold increase in the risk for this type of tumour. It was not possible to determine, however, whether the carcinogenic effect was exerted by these compounds or by impurities such as chlorinated dibenzodioxins and dibenzofurans that in almost all cases were part of the commercial preparations. PMID:444410

Influence of concentration, time and method of application of citric acid and sodium citrate in root conditioning

PubMed Central

CAVASSIM, Rodrigo; LEITE, Fábio Renato Manzolli; ZANDIM, Daniela Leal; DANTAS, Andrea Abi Rached; RACHED, Ricardo Samih Georges Abi; SAMPAIO, José Eduardo Cezar

2012-01-01

Objective The aim of this study was to establish the parameters of concentration, time and mode of application of citric acid and sodium citrate in relation to root conditioning. Material and Methods A total of 495 samples were obtained and equally distributed among 11 groups (5 for testing different concentrations of citric acid, 5 for testing different concentrations of sodium citrate and 1 control group). After laboratorial processing, the samples were analyzed under scanning electron microscopy. A previously calibrated and blind examiner evaluated micrographs of the samples. Non-parametric statistical analysis was performed to analyze the data obtained. Results Brushing 25% citric acid for 3 min, promoted greater exposure of collagen fibers in comparison with the brushing of 1% citric acid for 1 minute and its topical application at 1% for 3 min. Sodium citrate exposed collagen fibers in a few number of samples. Conclusion Despite the lack of statistical significance, better results for collagen exposure were obtained with brushing application of 25% citric acid for 3 min than with other application parameter. Sodium citrate produced a few number of samples with collagen exposure, so it is not indicated for root conditioning. PMID:22858707

Occupational dental erosion from exposure to acids: a review.

PubMed

Wiegand, Annette; Attin, Thomas

2007-05-01

Dental erosion is characterized as a disorder with a multifactorial aetiology including environmental acid exposure. The purpose of this article was to summarize and discuss the available information concerning occupational dental erosion. Information from original scientific papers, case reports and reviews with additional case reports listed in PubMed, Medline or EMBASE [search term: (dental OR enamel OR dentin) AND (erosion OR tooth wear) AND (occupational OR worker)] were included in the review. References from the identified publications were manually searched to identify additional relevant articles. The systematic search resulted in 59 papers, of which 42 were suitable for the present review. Seventeen papers demonstrated evidence that battery, galvanizing and associated workers exposed to sulphuric or hydrochloric acid were at higher risk of dental erosion. For other industrial workers, wine tasters and competitive swimmers, only a few clinical studies exist and these do not allow the drawing of definitive conclusions. Occupational acid exposure might increase the risk of dental erosion. Evidence for occupational dental erosion is limited to battery and galvanizing workers, while data for other occupational groups need to be confirmed by further studies.

Mild MPP+ exposure impairs autophagic degradation through a novel lysosomal acidity-independent mechanism.

PubMed

Miyara, Masatsugu; Kotake, Yaichiro; Tokunaga, Wataru; Sanoh, Seigo; Ohta, Shigeru

2016-10-01

Parkinson's disease (PD) is the second most common neurodegenerative disorder, but its underlying cause remains unknown. Although recent studies using PD-related neurotoxin MPP + suggest autophagy involvement in the pathogenesis of PD, the effect of MPP + on autophagic processes under mild exposure, which mimics the slow progressive nature of PD, remains largely unclear. We examined the effect of mild MPP + exposure (10 and 200 μM for 48 h), which induces a more slowly developing cell death, on autophagic processes and the mechanistic differences with acute MPP + toxicity (2.5 and 5 mM for 24 h). In SH-SY5Y cells, mild MPP + exposure predominantly inhibited autophagosome degradation, whereas acute MPP + exposure inhibited both autophagosome degradation and basal autophagy. Mild MPP + exposure reduced lysosomal hydrolase cathepsin D activity without changing lysosomal acidity, whereas acute exposure decreased lysosomal density. Lysosome biogenesis enhancers trehalose and rapamycin partially alleviated mild MPP + exposure induced impaired autophagosome degradation and cell death, but did not prevent the pathogenic response to acute MPP + exposure, suggesting irreversible lysosomal damage. We demonstrated impaired autophagic degradation by MPP + exposure and mechanistic differences between mild and acute MPP + toxicities. Mild MPP + toxicity impaired autophagosome degradation through novel lysosomal acidity-independent mechanisms. Sustained mild lysosomal damage may contribute to PD. We examined the effects of MPP + on autophagic processes under mild exposure, which mimics the slow progressive nature of Parkinson's disease, in SH-SY5Y cells. This study demonstrated impaired autophagic degradation through a reduction in lysosomal cathepsin D activity without altering lysosomal acidity by mild MPP + exposure. Mechanistic differences between acute and mild MPP + toxicity were also observed. Sustained mild damage of lysosome may be an underlying cause of Parkinson

Amino Acid Concentrations in the Hamster Central Auditory System and Long-Term Effects of Intense Tone Exposure

PubMed Central

Godfrey, Donald A.; Kaltenbach, James A.; Chen, Kejian; Ilyas, Omer; Liu, Xiaochen; Licari, Frank; Sacks, Justin; McKnight, Darwin

2015-01-01

Exposure to intense sounds often leads to loss of hearing of environmental sounds and hearing of a monotonous tonal sound not actually present, a condition known as tinnitus. Chronic physiological effects of exposure to intense tones have been reported for animals and should be accompanied by chemical changes present at long times after the intense sound exposure. By using a microdissection mapping procedure combined with high-performance liquid chromatography (HPLC), we have measured concentrations of nine amino acids, including those used as neurotransmitters, in the cochlear nucleus, inferior colliculus, medial geniculate, and auditory cortex of hamsters 5 months after exposure to an intense tone, compared with control hamsters of the same age. No very large differences in amino acid concentrations were found between exposed and control hamsters. However, increases of glutamate and γ-aminobutyrate (GABA) in some parts of the inferior colliculus of exposed hamsters were statistically significant. The most consistent differences between exposed and control hamsters were higher aspartate and lower taurine concentrations in virtually all regions of exposed hamsters, which reached statistical significance in many cases. Although these amino acids are not considered likely neurotransmitters, they indirectly have roles in excitatory and inhibitory neurotransmission, respectively. Thus, there is evidence for small, widespread, long-term increases in excitatory transmission and decreases in inhibitory transmission after a level of acoustic trauma previously shown to produce hearing loss and tinnitus. PMID:22715056

AMMONIA ABATEMENT SYSTEM FOR WHOLE-BODY SMALL ANIMAL INHALATION EXPOSURES TO ACID MODELS

EPA Science Inventory

Conducting whole-body acid aerosol inhalation exposures of laboratory animals is complicated by ammonia arising from the excrement of the test animals which is sufficient to completely neutralize much of the acid aerosol. he neutralization of acid by ammonia con only be controlle...

[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.

The effects of obesity on oesophageal function, acid exposure and the symptoms of gastro-oesophageal reflux disease.

PubMed

Anggiansah, R; Sweis, R; Anggiansah, A; Wong, T; Cooper, D; Fox, M

2013-03-01

Obese patients have an increased risk of gastro-oesophageal reflux disease; however, the mechanism underlying this association is uncertain. To test the hypothesis that mechanical effects of obesity on oesophageal function increase acid exposure and symptoms. Height, weight and waist circumference (WC) were measured in patients with typical reflux symptoms referred for manometry and 24 h ambulatory pH studies. Symptom severity was assessed by questionnaire. The association between obesity [WC, body mass index (BMI)], oesophageal function, acid exposure and reflux symptoms was assessed. Physiological measurements were obtained from 582 patients (median age 48, 56% female) of whom 406 (70%) completed symptom questionnaires. The prevalence of general obesity was greater in women (BMI ≥ 30 kg/m(2) ; F 23%:M 16%; P = 0.056), however more men had abdominal obesity (WC ≥ 99 cm (M 41%:F 28%; P = 0.001)). Oesophageal acid exposure increased with obesity (WC: R = 0.284, P < 0.001) and was associated also with lower oesophageal sphincter (LOS) pressure, reduced abdominal LOS length and peristaltic dysfunction (all P < 0.001). Univariable regression showed a negative association of WC with both LOS pressure and abdominal LOS length (R = -0.221 and -0.209 respectively; both P < 0.001). However, multivariable analysis demonstrated that the effects of increasing WC on oesophageal function do not explain increased acid reflux in obese patients. Instead, independent effects of obesity and oesophageal dysfunction on acid exposure were present. Reflux symptoms increased with acid exposure (R = 0.300; P < 0.001) and this association explained increased symptom severity in obese patients. Abdominal obesity (waist circumference) is associated with oesophageal dysfunction, increased acid exposure and reflux symptoms; however, this analysis does not support the mechanical hypothesis that the effects of obesity on oesophageal function are the cause of increased acid exposure in obese

Influence of waterborne gallic and pelargonic acid exposures on biochemical and reproductive parameters in the zebrafish (Danio rerio).

PubMed

Techer, Didier; Milla, Sylvain; Fontaine, Pascal; Viot, Sandrine; Thomas, Marielle

2017-01-01

Gallic and pelargonic acids are biologically derived substances receiving a growing interest as eco-friendly biocides with potential applications in freshwater system management. However, some data gaps remain to address their chronic ecotoxicity issue, particularly for fish. This work aimed at investigating the sublethal effects of a long-term waterborne exposure of zebrafish to these compounds. Mature fish were exposed to gallic or pelargonic acid at the concentrations of 0, 0.05, 0.5 and 5 mg/L during one month under semi-static conditions. Fecundity, hatching rate and median hatching time were regularly evaluated. Circulating sex hormone levels (11 ketotestosterone -11 KT, 17 βestradiol -E2-), plasma vitellogenin (Vtg), and gonad histology were monitored in males and females after exposure. Lactate dehydrogenase (LDH), total glutathione peroxydase (GPx) and glutathione-S transferase (GST) activities were assessed as enzymatic biomarkers of exposure in fish liver. Significant increases of GPx activity were reported in females exposed to both type of chemicals regardless the contamination level. Moreover, 5 mg/L gallic acid induced a decrease in 11-KT levels for males. For fish exposed to pelargonic acid, decreases in circulating hormone levels were reported respectively at 0.05 and 5 mg/L for 11-KT in males, and at 0.5 mg/L for E2 in females. However, no histological alteration in gonads neither significant variation in reproductive performances were detected following zebrafish exposure to gallic or pelargonic acid. Additional investigations concerning the mode of application and the environmental fate of these substances may warrant their further use in freshwater systems at concentrations compatible with biocidal/allelochemical effects. © 2015 Wiley Periodicals, Inc. Environ Toxicol 32: 227-240, 2017. © 2015 Wiley Periodicals, Inc.

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)

Urinary trans-trans muconic acid (exposure biomarker to benzene) and hippuric acid (exposure biomarker to toluene) concentrations in Mexican women living in high-risk scenarios of air pollution.

PubMed

Pruneda-Alvarez, Lucía G; Ruíz-Vera, Tania; Ochoa-Martínez, Angeles C; Pérez-Maldonado, Iván N

2017-11-02

This study aimed to determine t,t-muconic acid (t,t-MA; exposure biomarker for benzene) and hippuric acid (HA; exposure biomarker for toluene) concentrations in the urine of women living in Mexico. In a cross-sectional study, apparently healthy women (n = 104) were voluntarily recruited from localities with a high risk of air pollution; t,t-MA and HA in urine were quantified using a high-performance liquid chromatography (HPLC) technique. Mean urinary levels of t,t-MA ranged from 680 to 1,310 μg/g creatinine. Mean values of HA ranged from 0.38 to 0.87 g/g creatinine. In conclusion, compared to data recently reported in literature, we found high urinary levels of t,t-MA and HA in assessed women participating in this study. We therefore deem the implementation of a strategy aimed at the reduction of exposure as a necessary measure for the evaluated communities.

Prucalopride decreases esophageal acid exposure and accelerates gastric emptying in healthy subjects.

PubMed

Kessing, B F; Smout, A J P M; Bennink, R J; Kraaijpoel, N; Oors, J M; Bredenoord, A J

2014-08-01

The 5-HT4 receptor agonist prucalopride is a prokinetic drug which improves colonic motility. Animal data and in vitro studies suggest that prucalopride also affects gastric and esophageal motor function. We aimed to assess the effect of prucalopride on gastric emptying, esophageal motility, and gastro-esophageal reflux in man. In this double-blind, placebo-controlled, randomized, crossover study, we included 21 healthy volunteers who received 4 mg prucalopride or placebo per day for 6 days. We performed high-resolution manometry (HRM) followed by 120-min HRM-pH-impedance monitoring after a standardized meal, ambulatory 24-h pH-impedance monitoring, and gastric emptying for solids. Prucalopride decreased (median [IQR]) total acid exposure time (3.4 [2.5-5.6] vs 1.7 [0.8-3.5] %, p < 0.05). The total number of reflux events was unaffected by prucalopride, however, the number of reflux events extending to the proximal esophagus was reduced by prucalopride (15.5 [9.8-25.5] vs 10.5 [5.3-17.5], p < 0.05). Furthermore, prucalopride improved acid clearance time (77.5 [47.8-108.8] vs 44.0 [30.0-67.8] s, p < 0.05). Prucalopride did not affect the number of transient lower esophageal sphincter (LES) relaxations or their association with reflux events. Esophageal motility and basal pressure of the LES were not affected by prucalopride. Prucalopride increased gastric emptying (T1/2 ; 32.7 [27.9-44.6] vs 49.8 [37.7-55.0] min, p < 0.05) and decreased residue after 120 min (8.8 [4.4-14.8] vs 2.7 [1.3-5.4] %, p < 0.05). Prucalopride reduces esophageal acid exposure and accelerates gastric emptying in healthy male volunteers. These findings suggest that the drug could be effective for treatment of patients with reflux disease and functional dyspepsia. © 2014 John Wiley & Sons Ltd.

EFFECTS OF PERFLUOROOCTANOIC ACID EXPOSURE DURING PREGNANCY IN THE MOUSE

EPA Science Inventory

Title:

Effects Of Perfluorooctanoic Acid Exposure During Pregnancy In The Mouse

Authors & affiliations:
Lau, C., J.R. Thibodeaux*, R.G. Hanson* and J.M. Rogers. Reproductive Toxicology Division, NHEERL, ORD, U.S. EPA, Research Triangle Park, NC
Abstract:<...

Significance of urinary hippuric acid determination as an index of toluene exposure

PubMed Central

Ikeda, Masayuki; Ohtsuji, Hatsue

1969-01-01

Ikeda, Masayuki, and Ohtsuji, Hatsue (1969).Brit. J. industr. Med.,26, 244-246. Significance of urinary hippuric acid determination as an index of toluene exposure. Urine samples from 118 male workers in photogravure printing factories were analysed for hippuric acid. The urinary levels of hippuric acid were proportional to the environmental concentrations of toluene, although within wide variations. The urinary concentration of hippuric acid corresponding to 200 p.p.m. of toluene was 3·5 g./litre (specific gravity 1·016) or 4·3 g./g. creatinine. PMID:5794951

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

PubMed Central

BHATTI, PARVEEN; BLAIR, AARON; BELL, ERIN M.; ROTHMAN, NATHANIEL; LAN, QING; BARR, DANA B.; NEEDHAM, LARRY L.; PORTENGEN, LUTZEN; FIGGS, LARRY W.; VERMEULEN, ROEL

2009-01-01

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. PMID:19319162

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. Copyright © 2012 Elsevier Ltd. All rights reserved.

Preadaptation to Cold Stress in Salmonella enterica Serovar Typhimurium Increases Survival during Subsequent Acid Stress Exposure

PubMed Central

Shah, Jigna; Desai, Prerak T.; Chen, Dong; Stevens, John R.

2013-01-01

Salmonella is an important cause of bacterial food-borne gastroenteritis. Salmonella encounters multiple abiotic stresses during pathogen elimination methods used in food processing, and these stresses may influence its subsequent survivability within the host or in the environment. Upon ingestion, Salmonella is exposed to gastrointestinal acidity, a first line of the host innate defense system. This study tested the hypothesis that abiotic stresses encountered during food processing alter the metabolic mechanisms in Salmonella that enable survival and persistence during subsequent exposure to the host gastrointestinal acidic environment. Out of the four different abiotic stresses tested, viz., cold, peroxide, osmotic, and acid, preadaptation of the log-phase culture to cold stress (5°C for 5 h) significantly enhanced survival during subsequent acid stress (pH 4.0 for 90 min). The gene expression profile of Salmonella preadapted to cold stress revealed induction of multiple genes associated with amino acid metabolism, oxidative stress, and DNA repair, while only a few of the genes in the above-mentioned stress response and repair pathways were induced upon exposure to acid stress alone. Preadaptation to cold stress decreased the NAD+/NADH ratio and hydroxyl (OH·) radical formation compared with those achieved with the exposure to acid stress alone, indicating alteration of aerobic respiration and the oxidative state of the bacteria. The results from this study suggest that preadaptation to cold stress rescues Salmonella from the deleterious effect of subsequent acid stress exposure by induction of genes involved in stress response and repair pathways, by modification of aerobic respiration, and by redox modulation. PMID:24056458

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.

Hyperconnectivity of local neocortical microcircuitry induced by prenatal exposure to valproic acid.

PubMed

Rinaldi, Tania; Silberberg, Gilad; Markram, Henry

2008-04-01

Exposure to valproic acid (VPA) during embryogenesis can cause several teratogenic effects, including developmental delays and in particular autism in humans if exposure occurs during the third week of gestation. We examined the postnatal effects of embryonic exposure to VPA on microcircuit properties of juvenile rat neocortex using in vitro electrophysiology. We found that a single prenatal injection of VPA on embryonic day 11.5 causes a significant enhancement of the local recurrent connectivity formed by neocortical pyramidal neurons. The study of the biophysical properties of these connections revealed weaker excitatory synaptic responses. A marked decrease of the intrinsic excitability of pyramidal neurons was also observed. Furthermore, we demonstrate a diminished number of putative synaptic contacts in connection between layer 5 pyramidal neurons. Local hyperconnectivity may render cortical modules more sensitive to stimulation and once activated, more autonomous, isolated, and more difficult to command. This could underlie some of the core symptoms observed in humans prenatally exposed to valproic acid.

Mediation analysis with time varying exposures and mediators.

PubMed

VanderWeele, Tyler J; Tchetgen Tchetgen, Eric J

2017-06-01

In this paper we consider causal mediation analysis when exposures and mediators vary over time. We give non-parametric identification results, discuss parametric implementation, and also provide a weighting approach to direct and indirect effects based on combining the results of two marginal structural models. We also discuss how our results give rise to a causal interpretation of the effect estimates produced from longitudinal structural equation models. When there are time-varying confounders affected by prior exposure and mediator, natural direct and indirect effects are not identified. However, we define a randomized interventional analogue of natural direct and indirect effects that are identified in this setting. The formula that identifies these effects we refer to as the "mediational g-formula." When there is no mediation, the mediational g-formula reduces to Robins' regular g-formula for longitudinal data. When there are no time-varying confounders affected by prior exposure and mediator values, then the mediational g-formula reduces to a longitudinal version of Pearl's mediation formula. However, the mediational g-formula itself can accommodate both mediation and time-varying confounders and constitutes a general approach to mediation analysis with time-varying exposures and mediators.

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

Time dependent effect of chronic embryonic exposure to ethanol on zebrafish: Morphology, biochemical and anxiety alterations.

PubMed

Ramlan, Nurul Farhana; Sata, Nurul Syafida Asma Mohd; Hassan, Siti Norhidayah; Bakar, Noraini Abu; Ahmad, Syahida; Zulkifli, Syaizwan Zahmir; Abdullah, Che Azurahanim Che; Ibrahim, Wan Norhamidah Wan

2017-08-14

Exposure to ethanol during critical period of development can cause severe impairments in the central nervous system (CNS). This study was conducted to assess the neurotoxic effects of chronic embryonic exposure to ethanol in the zebrafish, taking into consideration the time dependent effect. Two types of exposure regimen were applied in this study. Withdrawal exposure group received daily exposure starting from gastrulation until hatching, while continuous exposure group received daily exposure from gastrulation until behavioural assessment at 6dpf (days post fertilization). Chronic embryonic exposure to ethanol decreased spontaneous tail coiling at 24hpf (hour post fertilization), heart rate at 48hpf and increased mortality rate at 72hpf. The number of apoptotic cells in the embryos treated with ethanol was significantly increased as compared to the control. We also measured the morphological abnormalities and the most prominent effects can be observed in the treated embryos exposed to 1.50% and 2.00%. The treated embryos showed shorter body length, larger egg yolk, smaller eye diameter and heart edema as compared to the control. Larvae received 0.75% continuous ethanol exposure exhibited decreased swimming activity and increased anxiety related behavior, while withdrawal ethanol exposure showed increased swimming activity and decreased anxiety related behavior as compared to the respective control. Biochemical analysis exhibited that ethanol exposure for both exposure regimens altered proteins, lipids, carbohydrates and nucleic acids of the zebrafish larvae. Our results indicated that time dependent effect of ethanol exposure during development could target the biochemical processes thus leading to induction of apoptosis and neurobehavioral deficits in the zebrafish larvae. Thus it raised our concern about the safe limit of alcohol consumption for pregnant mother especially during critical periods of vulnerability for developing nervous system. Copyright © 2017

Role of the lower esophageal sphincter on esophageal acid exposure - a review of over 2000 patients.

PubMed

Tsuboi, Kazuto; Hoshino, Masato; Sundaram, Abhishek; Yano, Fumiaki; Mittal, Sumeet K

2012-01-01

Three lower esophageal sphincter (LES) characteristics associated with gastro-esophageal reflux disease (GERD) are, LES pressure = 6 mmHg, abdominal length (AL) <1 cm and overall length (OL) <2 cm. The objective of this study was to validate this relationship and evaluate the extent of impact various LES characteristics have on the degree of distal esophageal acid exposure. A retrospective review of a prospectively maintained database identified patients who underwent esophageal manometry and pH studies at Creighton University Medical Center between 1984 and 2008. Patients with esophageal body dysmotility, prior foregut surgery, missing data, no documented symptoms or no pH study, were excluded. Study subjects were categorized as follows: (1) normal LES (N-LES): patients with LES pressure of 6-26 mmHg, AL = 1.0 cm and OL = 2 cm; (2) incompetent LES (Inc-LES): patients with LES pressure <6.0 mmHg orAL <1 cm or OL <2 cm; and (3) hypertensive LES (HTN-LES): patients with LES pressure >26.0 mmHg with AL = 1 cm and OL = 2 cm. The DeMeester score was used to compare differences in acid exposure between different groups. Two thousand and twenty patients satisfied study criteria. Distal esophageal acid exposure as reflected by the DeMeester score in patients with Inc-LES (median=20.05) was significantly higher than in patients with an N-LES (median=9.5), which in turn was significantly higher than in patients with an HTN-LES. Increasing LES pressure and AL provided protection against acid exposure in a graded fashion. Increasing number of inadequate LES characteristics were associated with an increase both in the percentage of patients with abnormal DeMeester score and the degree of acid exposure. LES pressure (=6 mmHg) and AL (<1 cm) are associated with increased lower esophageal acid exposure, and need to be addressed for definitive management of GERD.

Modeling and Experimental Studies of Obeticholic Acid Exposure and the Impact of Cirrhosis Stage

PubMed Central

LaCerte, C; Peyret, T; Gosselin, NH; Marier, JF; Hofmann, AF; Shapiro, D

2016-01-01

Obeticholic acid (OCA), a semisynthetic bile acid, is a selective and potent farnesoid X receptor (FXR) agonist in development for the treatment of chronic nonviral liver diseases. Physiologic pharmacokinetic models have been previously used to describe the absorption, distribution, metabolism, and excretion (ADME) of bile acids. OCA plasma levels were measured in healthy volunteers and cirrhotic subjects. A physiologic pharmacokinetic model was developed to quantitatively describe the ADME of OCA in patients with and without hepatic impairment. There was good agreement between predicted and observed increases in systemic OCA exposure in subjects with mild, moderate, and severe hepatic impairment, which were 1.4‐, 8‐, and 13‐fold relative to healthy volunteers. Predicted liver exposure for subjects with mild, moderate, and severe hepatic impairment were increased only 1.1‐, 1.5‐, and 1.7‐fold. In subjects with cirrhosis, OCA exposure in the liver, the primary site of pharmacological activity along with the intestine, is increased marginally (∼2‐fold). PMID:27743502

Diagnostics for Confounding of Time-varying and Other Joint Exposures.

PubMed

Jackson, John W

2016-11-01

The effects of joint exposures (or exposure regimes) include those of adhering to assigned treatment versus placebo in a randomized controlled trial, duration of exposure in a cohort study, interactions between exposures, and direct effects of exposure, among others. Unlike the setting of a single point exposure (e.g., propensity score matching), there are few tools to describe confounding for joint exposures or how well a method resolves it. Investigators need tools that describe confounding in ways that are conceptually grounded and intuitive for those who read, review, and use applied research to guide policy. We revisit the implications of exchangeability conditions that hold in sequentially randomized trials, and the bias structure that motivates the use of g-methods, such as marginal structural models. From these, we develop covariate balance diagnostics for joint exposures that can (1) describe time-varying confounding, (2) assess whether covariates are predicted by prior exposures given their past, the indication for g-methods, and (3) describe residual confounding after inverse probability weighting. For each diagnostic, we present time-specific metrics that encompass a wide class of joint exposures, including regimes of multivariate time-varying exposures in censored data, with multivariate point exposures as a special case. We outline how to estimate these directly or with regression and how to average them over person-time. Using a simulated example, we show how these metrics can be presented graphically. This conceptually grounded framework can potentially aid the transparent design, analysis, and reporting of studies that examine joint exposures. We provide easy-to-use tools to implement it.

Mediation analysis with time varying exposures and mediators

PubMed Central

VanderWeele, Tyler J.; Tchetgen Tchetgen, Eric J.

2016-01-01

Summary In this paper we consider causal mediation analysis when exposures and mediators vary over time. We give non-parametric identification results, discuss parametric implementation, and also provide a weighting approach to direct and indirect effects based on combining the results of two marginal structural models. We also discuss how our results give rise to a causal interpretation of the effect estimates produced from longitudinal structural equation models. When there are time-varying confounders affected by prior exposure and mediator, natural direct and indirect effects are not identified. However, we define a randomized interventional analogue of natural direct and indirect effects that are identified in this setting. The formula that identifies these effects we refer to as the “mediational g-formula.” When there is no mediation, the mediational g-formula reduces to Robins’ regular g-formula for longitudinal data. When there are no time-varying confounders affected by prior exposure and mediator values, then the mediational g-formula reduces to a longitudinal version of Pearl’s mediation formula. However, the mediational g-formula itself can accommodate both mediation and time-varying confounders and constitutes a general approach to mediation analysis with time-varying exposures and mediators. PMID:28824285

Time and Place as Modifiers of Personal UV Exposure.

PubMed

Diffey, Brian L

2018-05-30

It is a common belief that, if we want to limit our sun exposure during outdoor recreational activities and holidays in order to avoid sunburn or reduce our risk of skin cancer, we need to reach for the bottle of sunscreen or cover up with clothing. As important as these measures are, there is another way to enjoy our time outdoors and still benefit from the experience. In this article, we consider the impact of time, place, and behaviour outdoors on our exposure to solar ultraviolet (UV) radiation. Some of the simple actions we can take in controlling our UV exposure include being aware of the position of the sun in the sky, understanding how we can use the UV index to guide our outdoor exposure, and the importance of reducing our sun exposure around the middle of the day. Finally we review our preferred holiday activities and destinations, and the influence of outdoor leisure pursuits. By planning where and when we spend our leisure time in the sun, we can maximise our enjoyment whilst limiting our UV exposure.

Dermal exposure to chromium in the grinding of stainless and acid-proof steel.

PubMed

Mäkinen, Milja; Linnainmaa, Markku

2004-04-01

The aim of the study was to measure the dermal exposure levels of chromium dust during grinding of stainless and acid-proof steel parts. The potential dermal exposure of the body was measured with a patch sampling method and the actual exposure of hands with a hand-wash method. Simultaneously, personal air samples were also collected. The range of body and hand exposure to chromium dust was 4.04-3406 and 0.72-79.7 mg/h, respectively. Dust was distributed quite evenly to different body parts. Workers using hand-held grinding tools were more exposed than those using band grinders. It was judged that the sampling methods applied in this study gave a realistic estimation of exposure levels, because of the uniform distribution of contamination during grinding. Respiratory exposure was high compared to Finnish occupational exposure limit values.

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...

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 (...

Exposure to phthalic acid, phthalate diesters and phthalate monoesters from foodstuffs: UK total diet study results.

PubMed

Bradley, Emma L; Burden, Richard A; Bentayeb, Karim; Driffield, Malcolm; Harmer, Nick; Mortimer, David N; Speck, Dennis R; Ticha, Jana; Castle, Laurence

2013-01-01

Phthalates are ubiquitous in the environment and thus exposure to these compounds can occur in various forms. Foods are one source of such exposure. There are only a limited number of studies that describe the levels of phthalates (diesters, monoesters and phthalic acid) in foods and assess the exposure from this source. In this study the levels of selected phthalate diesters, phthalate monoesters and phthalic acid in total diet study (TDS) samples are determined and the resulting exposure estimated. The methodology for the determination of phthalic acid and nine phthalate monoesters (mono-isopropyl phthalate, mono-n-butyl phthalate, mono-isobutyl phthalate, mono-benzyl phthalate, mono-cyclohexyl phthalate, mono-n-pentyl phthalate, mono-(2-ethylhexyl) phthalate, mono-n-octyl phthalate and mono-isononyl phthalate) in foods is described. In this method phthalate monoesters and phthalic acid are extracted from the foodstuffs with a mixture of acidified acetonitrile and dichloromethane. The method uses isotope-labelled phthalic acid and phthalate monoester internal standards and is appropriate for quantitative determination in the concentration range of 5-100 µg kg⁻¹. The method was validated in-house and its broad applicability demonstrated by the analysis of high-fat, high-carbohydrate and high-protein foodstuffs as well as combinations of all three major food constituents. The methodology used for 15 major phthalate diesters has been reported elsewhere. Phthalic acid was the most prevalent phthalate, being detected in 17 food groups. The highest concentration measured was di-(2-ethylhexyl) phthalate in fish (789 µg kg⁻¹). Low levels of mono-n-butyl phthalate and mono-(2-ethylhexyl) phthalate were detected in several of the TDS animal-based food groups and the highest concentrations measured corresponded with the most abundant diesters (di-n-butyl phthalate and di-(2-ethylhexyl) phthalate). The UK Committee on Toxicity of Chemicals in Food, Consumer Products

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...

Profiles of Amino Acids and Acylcarnitines Related with Insecticide Exposure in Culex quinquefasciatus (Say)

PubMed Central

Martin-Park, Abdiel; Gomez-Govea, Mayra A.; Lopez-Monroy, Beatriz; Treviño-Alvarado, Víctor Manuel; Torres-Sepúlveda, María del Rosario; López-Uriarte, Graciela Arelí; Villanueva-Segura, Olga Karina; Ruiz-Herrera, María del Consuelo; Martinez-Fierro, Margarita de la Luz; Delgado-Enciso, Ivan; Flores-Suárez, Adriana E.; White, Gregory S.; Martínez de Villarreal, Laura E.; Ponce-Garcia, Gustavo; Black, William C.; Rodríguez-Sanchez, Irám Pablo

2017-01-01

Culex quinquefasciatus Say is a vector of many pathogens of humans, and both domestic and wild animals. Personal protection, reduction of larval habitats, and chemical control are the best ways to reduce mosquito bites and, therefore, the transmission of mosquito-borne pathogens. Currently, to reduce the risk of transmission, the pyrethroids, and other insecticide groups have been extensively used to control both larvae and adult mosquitoes. In this context, amino acids and acylcarnitines have never been associated with insecticide exposure and or insecticide resistance. It has been suggested that changes in acylcarnitines and amino acids profiles could be a powerful diagnostic tool for metabolic alterations. Monitoring these changes could help to better understand the mechanisms involved in insecticide resistance, complementing the strategies for managing this phenomenon in the integrated resistance management. The purpose of the study was to determine the amino acids and acylcarnitines profiles in larvae of Cx. quinquefasciatus after the exposure to different insecticides. Bioassays were performed on Cx. quinquefasciatus larvae exposed to the diagnostic doses (DD) of the insecticides chlorpyrifos (0.001 μg/mL), temephos (0.002 μg/mL) and permethrin (0.01 μg/mL). In each sample, we analyzed the profile of 12 amino acids and 31 acylcarnitines by LC-MS/MS. A t-test was used to determine statistically significant differences between groups and corrections of q-values. Results indicates three changes, the amino acids arginine (ARG), free carnitine (C0) and acetyl-carnitine (C2) that could be involved in energy production and insecticide detoxification. We confirmed that concentrations of amino acids and acylcarnitines in Cx. quinquefasciatus vary with respect to different insecticides. The information generated contributes to understand the possible mechanisms and metabolic changes occurring during insecticide exposure. PMID:28085898

Profiles of Amino Acids and Acylcarnitines Related with Insecticide Exposure in Culex quinquefasciatus (Say).

PubMed

Martin-Park, Abdiel; Gomez-Govea, Mayra A; Lopez-Monroy, Beatriz; Treviño-Alvarado, Víctor Manuel; Torres-Sepúlveda, María Del Rosario; López-Uriarte, Graciela Arelí; Villanueva-Segura, Olga Karina; Ruiz-Herrera, María Del Consuelo; Martinez-Fierro, Margarita de la Luz; Delgado-Enciso, Ivan; Flores-Suárez, Adriana E; White, Gregory S; Martínez de Villarreal, Laura E; Ponce-Garcia, Gustavo; Black, William C; Rodríguez-Sanchez, Irám Pablo

2017-01-01

Culex quinquefasciatus Say is a vector of many pathogens of humans, and both domestic and wild animals. Personal protection, reduction of larval habitats, and chemical control are the best ways to reduce mosquito bites and, therefore, the transmission of mosquito-borne pathogens. Currently, to reduce the risk of transmission, the pyrethroids, and other insecticide groups have been extensively used to control both larvae and adult mosquitoes. In this context, amino acids and acylcarnitines have never been associated with insecticide exposure and or insecticide resistance. It has been suggested that changes in acylcarnitines and amino acids profiles could be a powerful diagnostic tool for metabolic alterations. Monitoring these changes could help to better understand the mechanisms involved in insecticide resistance, complementing the strategies for managing this phenomenon in the integrated resistance management. The purpose of the study was to determine the amino acids and acylcarnitines profiles in larvae of Cx. quinquefasciatus after the exposure to different insecticides. Bioassays were performed on Cx. quinquefasciatus larvae exposed to the diagnostic doses (DD) of the insecticides chlorpyrifos (0.001 μg/mL), temephos (0.002 μg/mL) and permethrin (0.01 μg/mL). In each sample, we analyzed the profile of 12 amino acids and 31 acylcarnitines by LC-MS/MS. A t-test was used to determine statistically significant differences between groups and corrections of q-values. Results indicates three changes, the amino acids arginine (ARG), free carnitine (C0) and acetyl-carnitine (C2) that could be involved in energy production and insecticide detoxification. We confirmed that concentrations of amino acids and acylcarnitines in Cx. quinquefasciatus vary with respect to different insecticides. The information generated contributes to understand the possible mechanisms and metabolic changes occurring during insecticide exposure.

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 ...

Prolonged restraint stressor exposure in outbred CD-1 mice impacts microbiota, colonic inflammation, and short chain fatty acids.

PubMed

Maltz, Ross M; Keirsey, Jeremy; Kim, Sandra C; Mackos, Amy R; Gharaibeh, Raad Z; Moore, Cathy C; Xu, Jinyu; Bakthavatchalu, Vasudevan; Somogyi, Arpad; Bailey, Michael T

2018-01-01

Stressor-exposure has been shown to exacerbate inflammation and change the composition of the gastrointestinal microbiota; however stressor-induced effects on microbiota-derived metabolites and their receptors are unknown. Thus, bacterial-produced short chain fatty acids (SCFAs), as well as microbial community composition, were assessed in the colons of mice exposed to stress during infection with Citrobacter rodentium. Mice were exposed to overnight restraint on 7 consecutive nights, or left undisturbed as a control. After the first exposure of restraint, mice were orally challenged with C. rodentium or with vehicle. Microbial community composition was assessed using 16S rRNA gene sequencing and SCFA levels measured using gas chromatography-mass spectrometry (GC-MS). Pathogen levels and colonic inflammation were also assessed 6 days post-infection. Results demonstrated that the microbial community structure and SCFA production were significantly affected by both stressor exposure and C. rodentium-infection. Exposure to prolonged restraint in the absence of infection significantly reduced SCFAs (acetic acid, butyric acid, and propionic acid). Multiple bacterial taxa were affected by stressor exposure, with the relative abundance of Lactobacillus being significantly reduced and directly correlated with propionic acid. Lactobacillus abundances were inversely correlated with colonic inflammation, supporting the contention that Lactobacillus helps to regulate mucosal inflammatory responses. Our data indicates that restraint stressor can have significant effects on pathogen-induced colonic inflammation and suggest that stressor-induced changes in the microbiota, microbial-produced SCFAs and their receptors may be involved.

Light exposure during storage preserving soluble sugar and l-ascorbic acid content of minimally processed romaine lettuce (Lactuca sativa L.var. longifolia).

PubMed

Zhan, Lijuan; Hu, Jinqiang; Ai, Zhilu; Pang, Lingyun; Li, Yu; Zhu, Meiyun

2013-01-01

Minimally processed romaine lettuce (MPRL) leaves were stored in light condition (2500lux) or darkness at 4°C for 7d. Light exposure significantly delayed the degradation of chlorophyll and decrease of glucose, reducing sugar, and sucrose content, and thus preserved more total soluble solid (TSS) content at the end of storage in comparison with darkness. While, it did not influenced starch content that progressively decreased over time. The l-ascorbic acid (AA) accumulated in light-stored leaves, but deteriorated in dark-stored leaves during storage. The dehydroascorbic acid (DHA) increased in all leaves stored in both light and dark condition, of which light condition resulted in less DHA than darkness. In addition, the fresh weight loss and dry matter significantly increased and these increases were accelerated by light exposure. Conclusively, light exposure in applied intensity effectively alleviated MPRL quality deterioration by delaying the decreases of pigments, soluble sugar, TSS content and accumulating AA. Copyright © 2012 Elsevier Ltd. All rights reserved.

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.

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.

Dose-time-response association between occupational asbestos exposure and pleural mesothelioma.

PubMed

Lacourt, Aude; Lévêque, Emilie; Guichard, Elie; Gilg Soit Ilg, Anabelle; Sylvestre, Marie-Pierre; Leffondré, Karen

2017-09-01

Early occupational exposure to asbestos has been shown to be associated with an increased risk of pleural mesothelioma (PM), which suggests that the timing of exposure might play a role in the dose-response relationship. However, none studies has evaluated the relative impact of increasing the annual intensity of occupational exposure to asbestos at each time of the whole exposure history. Yet such evaluation would allow the comparison of the risks of PM associated with different longitudinal profiles of occupational exposure to asbestos. Our objective was to estimate the time-dependent relative impact of asbestos exposure intensity over the whole occupational history and to compare the resulting estimated risks of PM associated with different profiles of exposure, using data from a large French case-control study. This study included 1196 male cases recruited in 1987-2006 and 2369 matched controls on birth year. Occupational exposure to asbestos was assessed using a job exposure matrix and represented in logistic regression models using a flexible weighted cumulative index of exposure. Due to much stronger weights of early doses of asbestos exposure, subjects who accumulated 20 fibres/mL over their entire job history with high doses during the first years and low doses thereafter were at higher risk of PM than those who accumulated most of the doses later (OR=2.37 (95% CI 2.01 to 2.87)). This study provides new insights on the dose-time-response relationship between occupational asbestos and PM and illustrates the importance of considering timing of exposure in its association with cancer risk. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

The novel, peripherally restricted GABAB receptor agonist lesogaberan (AZD3355) inhibits acid reflux and reduces esophageal acid exposure as measured with 24-h pHmetry in dogs.

PubMed

Brändén, Lena; Fredriksson, Anita; Harring, Emelie; Jensen, Jörgen; Lehmann, Anders

2010-05-25

While patients with symptoms of gastroesophageal reflux disease generally respond well to proton pump inhibitors, 20-30% continue to experience troublesome symptoms. In such cases, agents that target transient lower esophageal sphincter (LES) relaxation may be useful as add-on therapy to proton pump inhibitors. The GABAB receptor agonist baclofen inhibits transient LES relaxation but it is not an ideal agent due to central nervous system activity. Lesogaberan (AZD3355) is a peripherally restricted GABAB receptor agonist with limited central nervous system activity that inhibits transient LES relaxation in dogs. In the present study, the comparative effects of lesogaberan (7 micromol/kg) and baclofen (2.8 micromol/kg) on reflux were studied in dogs using 24-h pHmetry. Drugs (or vehicle control) were administered orally prior to the first meal of the day, and the number of reflux episodes (pH<4 for > or = 5 s) and acid exposure time were computed for the 24-h monitoring period. The mean (S.E.M.) number of reflux episodes/24 h was 4.6 (0.4) and 6.4 (0.6) for lesogaberan and baclofen, respectively, versus 10.7 (0.5) for control (P<0.0001 for both). Acid exposure time was 51.2 (4.5) min for control versus 23.6 (3.8) min for lesogaberan (P<0.0001) and 35.4 (6.5) min with baclofen (P=0.05). It is concluded that lesogaberan significantly reduces acid reflux in dogs, with comparable efficacy to baclofen. Copyright 2010 Elsevier B.V. All rights reserved.

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marchini, T.; Magnani, N.D.; Paz, M.L.

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 acidmore » 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. �

Occupational exposure to herbs containing aristolochic acids increases the risk of urothelial carcinoma in Chinese herbalists.

PubMed

Yang, Hsiao-Yu; Wang, Jung-Der; Lo, Tsai-Chang; Chen, Pau-Chung

2013-01-01

Aristolochic acid can cause urothelial carcinoma. Herbal remedies containing aristolochic acids were previously categorized as proven group 1 human carcinogens by the WHO cancer agency, the International Agency for Research on Cancer. However, the health effect on workers exposed to aristolochic acid is unclear. Fangchi, a representative herb containing aristolochic acid, is commonly used in the Chinese herbal medicine industry. We determined whether workers exposed to fangchi are at increased risk for urothelial carcinoma. We designed a case-control study based in a national representative cohort of Chinese herbalists. This study analyzed 6,564 Chinese herbalists employed between 1985 and 1998. All incident cases of urothelial carcinoma that occurred between 1988 and 2001 were defined as the case group. Controls were selected from the baseline cohort in a randomized manner. A total of 24 cases and 140 controls were included in analysis. Information about fangchi exposure was obtained in a questionnaire survey administered in 2002. Processing, selling or dispensing herbs containing fangchi significantly increased the risk of urothelial carcinoma (HR 2.4, 95% CI 1.1-5.3, p = 0.03). This relationship was independent of cigarette smoking or potential arsenic exposure from drinking water from deep wells. Exposure to the Chinese herbal drug fangchi increases the risk of urothelial carcinoma in herbalists. Appropriate medical monitoring is warranted for workers who have similar exposure. Copyright © 2013 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Acute hydrofluoric acid exposure reported to Taiwan Poison Control Center, 1991-2010.

PubMed

Wu, M-L; Yang, C-C; Ger, J; Tsai, W-J; Deng, J-F

2014-05-01

Hydrofluoric acid (HF) is a dangerous chemical that can cause severe cutaneous burns as well as possible systemic toxicity. We retrospectively analyzed all human HF exposure cases reported to the National Poison Control Center of Taiwan between 1991 and 2010. In this 20-year survey, 324 calls were identified, with a majority of dermal exposure (84%). Occupational exposure accounted for 80% of all cases, with workers in semiconductor industry (61%), cleaning industry (15%), chemical or metal industry (13%), and other industries (11%). Electrolyte imbalances were uncommon, hypocalcemia, hypomagnesemia, and hypokalemia were recorded in 8.6%, 1.2%, and 1.5% of all cases, respectively. Most cases (64%) of dermal exposure received antidotal treatment. Treatment modalities of dermal exposure included calcium gluconate soaking, 49.8%; intravenous calcium, 20.6%; and topical use of calcium gluconate gel, 13.9%. Twenty patients (7%) received surgery. Following HF exposure, the majority of patients presented with mild (56.5%) or moderate (36.7%) toxic effects. However, four patients were severely intoxicated; two patients died of HF-related dysrhythmia and shock. Significant symptomology may occur following HF exposure, and most of the HF exposure required hospitals evaluation. Calcium gluconate soaks appear to be effective in reducing local pain and tissue damage. Hyperkalemia should not be overemphasized as a common finding in HF exposure, hypokalemia tends to occur in cases of severe HF poisoning.

Exposure to 2,4-dichlorophenoxyacetic acid induced PPARβ-dependent disruption of glucose metabolism in HepG2 cells.

PubMed

Sun, Haidong; Shao, Wentao; Liu, Hui; Jiang, Zhaoyan

2018-04-09

2,4-Dichlorophenoxyacetic acid is one of the most widely used herbicides. Its impact on health is increasingly attracting great attentions. This study aimed to investigate the effect of 2,4-dichlorophenoxyacetic acid on glucose metabolism in HepG2 cells and the underlying mechanism. After 24 h exposure to 2,4-dichlorophenoxyacetic acid, glycogen was measured by PAS staining and glucose by ELISA in HepG2 cells. The expression of genes involved in glucose metabolism was measured by real-time PCR, Western blotting, and immunofluorescence. HepG2 cells presented more extracellular glucose consumption and glycogen content after exposed to 2,4-dichlorophenoxyacetic acid. Expression of gluconeogenesis-related genes, FoxO1, and CREB is significantly elevated. Moreover, PPARβ was up-regulated dose-dependently. SiRNA knockdown of PPARβ completely rescued the increase of glycogen accumulation and glucose uptake, and the up-regulation of FOXO1 and CREB expression. Our findings propose novel mechanisms that 2,4-dichlorophenoxyacetic acid causes glucose metabolism dysfunction through PPARβ in HepG2 cells.

The effect of theobromine 200 mg/l topical gel exposure duration against surface enamel hardness resistance from 1% citric acid

NASA Astrophysics Data System (ADS)

Herisa, H. M.; Noerdin, A.; Eriwati, Y. K.

2017-08-01

Theobromine can be used to prevent the demineralization of enamel and can stimulate the growth of new enamels. This study analyzes the effect of theobromine’s gel duration exposure on enamel hardness resistance from 1% citric acid. Twenty-eight specimens were divided into three experimental groups; were exposed to theobromine gel 200 mg/l for 16, 48, and 96 minutes; and were then immersed in 1% citric acid. The control group was only immersed in 1% citric acid. Results: A Wilcoxon test showed a significant increase and decrease in enamel microhardness after exposure to theobromine gel and citric acid (p < 0.05). A Mann-Whitney test showed a significant increase and decrease in enamel microhardness between different durations of exposure to theobromine gel and immersion in citric acid (p < 0.05). The application of theobromine gel 200mg/L increased enamel microhardness but did not contribute to the enamel’s hardness resistance after immersion in 1% citric acid. The duration of theobromine gel application affected enamel microhardness and acid resistance.

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...

Normal human gingival fibroblasts undergo cytostasis and apoptosis after long-term exposure to butyric acid.

PubMed

Shirasugi, Michihiro; Nishioka, Keisuke; Yamamoto, Toshiro; Nakaya, Takaaki; Kanamura, Narisato

2017-01-22

The causes of periodontal disease are complex. Butyric acid, a metabolite of periodontopathic bacteria such as Porphyromonas gingivalis, acts as a histone deacetylase inhibitor that has a direct effect on mRNA expression. Butyric acid produced by Clostridium butyricum in the intestinal tract induces differentiation of regulatory T cells, thereby suppressing inflammation in the gut. Mice lacking Clostridium butyricum in the intestinal tract suffer from colitis. By contrast, butyric acid in the oral cavity worsens periodontal disease. Periodontal disease is a chronic condition in which periodontal tissue is exposed to virulence factors (such as butyric acid); however, no study has examined the effects of long-term exposure to butyric acid. The present study demonstrated that long-term exposure of human gingival fibroblasts (HGFs) to butyric acid induced cytostasis and apoptosis via the intrinsic and extrinsic pathways. Butyric acid inhibited the division of HGFs by altering expression of mRNAs encoding cyclins. Butyric acid induced apoptosis in HGFs via the intrinsic pathway, followed by activation of caspase 9; there was no DNA damage or p53 activation. Butyric acid also upregulated expression of TNF-α mRNA and protein by HGFs. Furthermore TNF-α induced apoptosis by activating caspase 8 (the extrinsic pathway) and by inducing production of pro-inflammatory cytokines. Taken together, the results show that butyric acid induced cytostasis and apoptosis in HGFs, accompanied by production of pro-inflammatory cytokines. It thus acts as a death ligand and plays a critical role as a prophlogistic substance. Copyright © 2016 Elsevier Inc. All rights reserved.

Assessment of occupational exposure to gaseous peracetic acid.

PubMed

Dugheri, Stefano; Bonari, Alessandro; Pompilio, Ilenia; Colpo, Marco; Montalti, Manfredi; Mucci, Nicola; Arcangeli, Giulio

2018-02-07

In order to assess short-term exposure to peracetic acid (PAA) in disinfection processes, the Authors compared 4 industrial hygiene monitoring methods to evaluate their proficiency in measuring airborne PAA concentrations. An active sampling by basic silica gel impregnated with methyl p-tolyl sulfoxide (MTSO), a passive solid phase micro-extraction technique using methyl p-tolyl sulfide (MTS) as on-fiber derivatization reagent, an electrochemical direct-reading PAA monitor, and a novel visual test strip PAA detector doped with 2,2'-azino-bis (3-ethylbenzothiazoline)-6-sulfonate were evaluated and tested over the range of 0.06-16 mg/m3, using dynamically generated PAA air concentrations. The linear regression analysis of linearity and accuracy showed that the 4 methods were suitable for PAA monitoring. Peracetic acid monitoring in several use applications showed that the PAA concentration (1.8 mg/m3) was immediately dangerous to life or health as proposed by the National Institute of Occupational Safety and Health, and was frequently exceeded in wastewater treatment (up to 7.33 mg/m3), and sometimes during food and beverage processes and hospital high-level disinfection operations (up to 6.8 mg/m3). The methods were suitable for the quick assessment of acute exposure in PAA environmental monitoring and can assist in improving safety and air quality in the workplace where this disinfectant is used. These monitoring methods allowed the evaluation of changes to work out practices to reduce PAA vapor concentrations during the operations when workers are potentially overexposed to this strong antioxidant agent. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Complex cardiac defects after ethanol exposure during discrete cardiogenic events in zebrafish: Prevention with folic acid

PubMed Central

Sarmah, Swapnalee; Marrs, James A.

2014-01-01

BACKGROUND Fetal alcohol spectrum disorder (FASD) describes a range of birth defects including various congenital heart defects (CHDs). Mechanisms of FASD-associated CHDs are not understood. Whether alcohol interferes with a single critical event or with multiple events in heart formation is not known. RESULTS Our zebrafish embryo experiments showed that ethanol interrupts different cardiac regulatory networks and perturbed multiple steps of cardiogenesis (specification, myocardial migration, looping, chamber morphogenesis and endocardial cushion formation). Ethanol exposure during gastrulation until cardiac specification or during myocardial midline migration did not produce severe or persistent heart development defects. However, exposure comprising gastrulation until myocardial precursor midline fusion or during heart patterning stages produced aberrant heart looping and defective endocardial cushions. Continuous exposure during entire cardiogenesis produced complex cardiac defects leading to severely defective myocardium, endocardium, and endocardial cushions. Supplementation of retinoic acid with ethanol partially rescued early heart developmental defects, but the endocardial cushions did not form correctly. In contrast, supplementation of folic acid rescued normal heart development, including the endocardial cushions. CONCLUSIONS Our results indicate that ethanol exposure interrupted divergent cardiac morphogenesis events causing heart defects. Folic acid supplementation was effective in preventing a wide spectrum of ethanol-induced heart developmental defects. PMID:23832875

Time series analysis of personal exposure to ambient air pollution and mortality using an exposure simulator.

PubMed

Chang, Howard H; Fuentes, Montserrat; Frey, H Christopher

2012-09-01

This paper describes a modeling framework for estimating the acute effects of personal exposure to ambient air pollution in a time series design. First, a spatial hierarchical model is used to relate Census tract-level daily ambient concentrations and simulated exposures for a subset of the study period. The complete exposure time series is then imputed for risk estimation. Modeling exposure via a statistical model reduces the computational burden associated with simulating personal exposures considerably. This allows us to consider personal exposures at a finer spatial resolution to improve exposure assessment and for a longer study period. The proposed approach is applied to an analysis of fine particulate matter of <2.5 μm in aerodynamic diameter (PM(2.5)) and daily mortality in the New York City metropolitan area during the period 2001-2005. Personal PM(2.5) exposures were simulated from the Stochastic Human Exposure and Dose Simulation. Accounting for exposure uncertainty, the authors estimated a 2.32% (95% posterior interval: 0.68, 3.94) increase in mortality per a 10 μg/m(3) increase in personal exposure to PM(2.5) from outdoor sources on the previous day. The corresponding estimates per a 10 μg/m(3) increase in PM(2.5) ambient concentration was 1.13% (95% confidence interval: 0.27, 2.00). The risks of mortality associated with PM(2.5) were also higher during the summer months.

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

PubMed Central

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

2017-01-01

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 (3.5 g/kg, i.p.), VPA (200 mg/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

Channel-Island Connectivity Affects Water Exposure Time Distributions in a Coastal River Delta

NASA Astrophysics Data System (ADS)

Hiatt, Matthew; Castañeda-Moya, Edward; Twilley, Robert; Hodges, Ben R.; Passalacqua, Paola

2018-03-01

The exposure time is a water transport time scale defined as the cumulative amount of time a water parcel spends in the domain of interest regardless of the number of excursions from the domain. Transport time scales are often used to characterize the nutrient removal potential of aquatic systems, but exposure time distribution estimates are scarce for deltaic systems. Here we analyze the controls on exposure time distributions using a hydrodynamic model in two domains: the Wax Lake delta in Louisiana, USA, and an idealized channel-island complex. In particular, we study the effects of river discharge, vegetation, network geometry, and tides and use a simple model for the fractional removal of nitrate. In both domains, we find that channel-island hydrological connectivity significantly affects exposure time distributions and nitrate removal. The relative contributions of the island and channel portions of the delta to the overall exposure time distribution are controlled by island vegetation roughness and network geometry. Tides have a limited effect on the system's exposure time distribution but can introduce significant spatial variability in local exposure times. The median exposure time for the WLD model is 10 h under the conditions tested and water transport within the islands contributes to 37-50% of the network-scale exposure time distribution and 52-73% of the modeled nitrate removal, indicating that islands may account for the majority of nitrate removal in river deltas.

Acid reflux episodes sensitize the esophagus to perception of weakly acidic and mixed reflux in non-erosive reflux disease patients.

PubMed

Emerenziani, S; Ribolsi, M; Guarino, M P L; Balestrieri, P; Altomare, A; Rescio, M P; Cicala, M

2014-01-01

Non-erosive reflux disease (NERD) patients are more sensitive than erosive esophagitis patients to weakly acidic reflux and to the presence of gas in the refluxate. Intra-esophageal acid perfusion sensitizes esophageal receptors to mechanical and chemical stimuli. To establish whether acid sensitization plays a role in the perception of weakly acidic and mixed reflux episodes, 29 NERD patients, responders and 14 non-responders to proton pump inhibitors (PPIs), underwent pH-impedance monitoring. Non-responders repeated the study while on PPIs. To assess the effect of acid exposure on symptom perception, the time period with pH below 4 was measured in 15- and 30-minute time-windows preceding the onset of each reflux episode. Considering weakly acidic and mixed refluxes, both in responder and non-responder patients (off PPIs), the symptomatic refluxes were preceded by a significantly higher cumulative acid exposure than the asymptomatic refluxes. In all patients, following acid reflux, the percentage of symptomatic weakly acidic reflux episodes was significantly higher than that of asymptomatic refluxes. Non-responder patients, off-treatment, were characterized by a lower proportion of weakly acidic reflux and mixed reflux episodes. In the non-responder patients on PPI, only mixed and weakly symptomatic reflux episodes were preceded by a higher cumulative acid exposure. In NERD patients, spontaneous acid reflux enhances subsequent reflux perception, regardless of acidity or liquid/mixed composition of episodes; in non-responder patients on PPIs, only the perception of mixed and weakly acidic reflux episodes seems to be mediated by a preceding acid exposure. © 2013 John Wiley & Sons Ltd.

DDT exposure of zebrafish embryos enhances seizure susceptibility: relationship to fetal p,p'-DDE burden and domoic acid exposure of California sea lions.

PubMed

Tiedeken, Jessica A; Ramsdell, John S

2009-01-01

California sea lions have a large body burden of organochlorine pesticides, and over the last decade they have also been subject to domoic acid poisoning. Domoic acid poisoning, previously recognized in adult animals, is now viewed as a major cause of prenatal mortality. The appearance of a chronic juvenile domoic acid disease in the sea lions, characterized by behavioral abnormalities and epilepsy, is consistent with early life poisoning and may be potentiated by organochlorine burden. We investigated the interactive effect of DDT (dichlorodiphenyltrichloroethane) on neurodevelopment using a zebrafish (Danio rerio) model for seizure behavior to examine the susceptibility to domoic acid-induced seizures after completion of neurodevelopment. Embryos were exposed (6-30 hr postfertilization) to either o,p'-DDT or p,p'-DDE (dichlorodiphenyldichloroethylene) during neurodevelopment via a 0.1% dimethyl sulfoxide solution. These larval (7 days postfertilization) fish were then exposed to either the seizure-inducing drug pentylenetetrazol (PTZ) or domoic acid; resulting seizure behavior was monitored and analyzed for changes using cameras and behavioral tracking software. Embryonic exposure to DDTs enhanced PTZ seizures and caused distinct and increased seizure behaviors to domoic acid, most notably a type of head-shaking behavior. These studies demonstrate that embryonic exposure to DDTs leads to asymptomatic animals at completion of neurodevelopment with greater sensitivity to domoic acid-induced seizures. The body burden levels of p,p'-DDE are close to the range recently found in fetal California sea lions and suggest a potential interactive effect of p,p'-DDE embryonic poisoning and domoic acid toxicity.

Surface characterisation of ethylene propylene diene rubber upon exposure to aqueous acidic solution

NASA Astrophysics Data System (ADS)

Mitra, Susanta; Ghanbari-Siahkali, Afshin; Kingshott, Peter; Hvilsted, Søren; Almdal, Kristoffer

2006-07-01

Two types of pure ethylene propylene diene rubbers were exposed to two different acids for varying period of time. Surface characterisation was carried out using X-ray photoelectron spectroscopy (XPS). Two EPDM rubbers selected for this study were comparable in co-monomer compositions but significantly different with respect to molar mass and the presence of long chain branching. Both rubbers contained 5-ethylidene-2-norbornene (ENB) as diene. Solution cast films of pure EPDM samples were exposed in two different acidic solutions, viz. chromosulphuric (Cr (VI)/H 2SO 4) and sulphuric acid (H 2SO 4) (20%, v/v) at ambient temperature from 1 to 12 weeks. XPS analysis indicated that several oxygenated species were formed on the surface of both rubbers after exposure. It was postulated from the XPS analyses that both aqueous acidic solutions attacked the olefinic double bonds (C dbnd C) of ENB. Furthermore, 20% Cr (VI)/H 2SO 4 also attacked the allylic carbon-hydrogen (C sbnd H) bonds of ENB resulting in more oxygenated species on the surface compared to 20% H 2SO 4 under identical conditions. Cr (VI) in the 20% Cr (VI)/H 2SO 4 was found to play an important role in alteration of surface chemistry. Studies using a model system consisting of EPDM mixed with Cr (VI) and Cr (III) salts revealed that the change of oxidation state from Cr (VI) to Cr (III) as a consequence of direct involvement of Cr (VI) in the chemical alteration of EPDM surfaces. Interestingly, the presence of long chain branching and molar mass did not significantly influence the chemical processes owing to the acid treatment.

Assessment of skin exposure to nickel, chromium and cobalt by acid wipe sampling and ICP-MS.

PubMed

Lidén, Carola; Skare, Lizbet; Lind, Birger; Nise, Gun; Vahter, Marie

2006-05-01

There is a great need to accurately assess skin exposure to contact allergens. We have developed a technique for assessment of skin exposure to nickel, chromium and cobalt using acid wipe sampling by cellulose wipes with 1% nitric acid. Chemical analysis was performed by inductively coupled plasma mass spectrometry (ICP-MS). The recovery of nickel, chromium and cobalt from arms and palms was 93%. The analytical result is expressed in terms of mass per unit area (microg/cm(2)). The developed acid wipe sampling technique is suitable for determination of nickel, chromium and cobalt deposited on the skin. The technique may be used in workplace studies, in studies of individuals in the general population, in dermatitis patients, in identification of risk groups, as well as in developing preventive strategies and in follow-up after intervention.

Influence of long-term exposure to simulated acid rain on development, reproduction and acaricide susceptibility of the carmine spider mite, Tetranychus cinnabarinus

PubMed Central

Wang, Jin-Jun; Zhang, Jian-Ping; He, Lin; Zhao, Zhi-Mo

2006-01-01

Development, reproduction and acaricide susceptibility of Tetranychus cinnabarinus (Boisduvals) (Acari: Tetranychidae) were investigated after long-term (about 40 generations) exposure to various levels of acid rain; pH 2.5, 3.0, 4.0, and 5.6. Deionized water (pH 6.8) served as a control. The mites were reared on eggplant leaves at 28°C, 80%RH and a photoperiod of 14:10 (L:D) in the laboratory. The results showed that the duration of the immature stage was significantly affected by acid rain exposure. The shortest duration (8.90 days) was recorded for populations exposed to pH 5.6 acid rain, while the longest duration (9.37 days) occurred after exposure to pH 2.5 acid rain. Compared with the control population, adult longevity was shortened with an increase in acidity. Similarly, the oviposition duration was also shortened by an increase in acidity. Statistically, female fecundity did not differ significantly between pH 5.6, pH 4.0 and control populations, but did differ significantly between the control population and those exposed to pH 2.5 and pH 3.0 acid rain. This suggested that the mite suffered reproductive defects after long-term exposure to acid rain with higher acidity (pH 2.5 and 3.0). The intrinsic rate of increase among different populations was not significantly affected, but the net reproductive rate of populations exposed to pH 2.5 and 3.0 acid rain was significantly less than pH4.0, 5.6, and control populations. Bioassay results showed that after long-term exposure to acid rain, susceptibility of the mites to two acaricides, dichlorvos and fenpropathrin, did not change significantly. PMID:19537978

Impact of diesel exhaust exposure on the liver of mice fed on omega-3 polyunsaturated fatty acids-deficient diet.

PubMed

Umezawa, Masakazu; Nakamura, Masayuki; El-Ghoneimy, Ashraf A; Onoda, Atsuto; Shaheen, Hazem M; Hori, Hiroshi; Shinkai, Yusuke; El-Sayed, Yasser S; El-Far, Ali H; Takeda, Ken

2018-01-01

Exposure to diesel exhaust (DE) exacerbates non-alcoholic fatty liver disease, and may systemically affect lipid metabolism. Omega-3 polyunsaturated fatty acids (n-3 PUFA) have anti-inflammatory activity and suppresses hepatic triacylglycerol accumulation, but many daily diets are deficient in this nutrient. Therefore, the effect of DE exposure in mice fed n-3 PUFA-deficient diet was investigated. Mice were fed control chow or n-3 PUFA-deficient diet for 4 weeks, then exposed to clean air or DE by inhalation for further 4 weeks. Liver histology, plasma parameters, and expression of fatty acid synthesis-related genes were evaluated. N-3 PUFA-deficient diet increased hepatic lipid droplets accumulation and expression of genes promoting fatty acid synthesis: Acaca, Acacb, and Scd1. DE further increased the plasma leptin and the expression of fatty acid synthesis-related genes: Acacb, Fasn, and Scd1. N-3 PUFA-deficient diet and DE exposure potentially enhanced hepatic fatty acid synthesis and subsequently accumulation of lipid droplets. The combination of low-dose DE exposure and intake of n-3 PUFA-deficient diet may be an additional risk factor for the incidence of non-alcoholic fatty liver disease. The present study suggests an important mechanism for preventing toxicity of DE on the liver through the incorporation of n-3 PUFAs in the diet. Copyright © 2017 Elsevier Ltd. All rights reserved.

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.

Increased colonic bile acid exposure: a relevant factor for symptoms and treatment in IBS.

PubMed

Bajor, Antal; Törnblom, Hans; Rudling, Mats; Ung, Kjell-Arne; Simrén, Magnus

2015-01-01

Bile acids may play a role in the pathogenesis of IBS. We investigated the potential effects of bile acids entering the colon and its role in the symptom pattern in IBS. We measured 75Se-labelled homocholic acid-taurine (75SeHCAT) retention, and serum levels of 7α-hydroxy-4-cholesten-3-one (C4) and fibroblast growth factor (FGF) 19 in patients with IBS (n=141) and control subjects (75SeHCAT n=29; C4 and FGF19 n=435). In patients with IBS stool frequency and form, as well as GI symptom severity were registered, and in a proportion of patients colonic transit time and rectal sensitivity were measured (n=66). An 8-week open-label treatment with colestipol was offered to patients with 75SeHCAT <20%, and the effect of treatment was evaluated with IBS severity scoring system and adequate relief of IBS symptoms. Compared with controls, patients with IBS had lower 75SeHCAT values (p=0.005), higher C4c levels (C4 corrected for cholesterol) (p<0.001), but similar FGF19 levels. Abnormal 75SeHCAT retention (<10%) was seen in 18% of patients, whereas 23% had elevated C4c levels. Patients with IBS with 75SeHCAT retention <10% had more frequent stools, accelerated colonic transit time, rectal hyposensitivity, a higher body mass index, higher C4c and lower FGF19 levels. Colestipol treatment improved IBS symptoms (IBS severity scoring system 220±109 vs. 277±106; p<0.01), and 15/27 patients fulfilled criteria for treatment response (adequate relief ≥50% of weeks 5-8). Increased colonic bile acid exposure influences bowel habit and colonic transit time in patients with IBS. A high response rate to open label treatment with colestipol supports this, but placebo-controlled studies are warranted. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

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.

Understanding the exposure-time effect on speckle contrast measurements for laser displays

NASA Astrophysics Data System (ADS)

Suzuki, Koji; Kubota, Shigeo

2018-02-01

To evaluate the influence of exposure time on speckle noise for laser displays, speckle contrast measurement method was developed observable at a human eye response time using a high-sensitivity camera which has a signal multiplying function. The nonlinearity of camera light sensitivity was calibrated to measure accurate speckle contrasts, and the measuring lower limit noise of speckle contrast was improved by applying spatial-frequency low pass filter to the captured images. Three commercially available laser displays were measured over a wide range of exposure times from tens of milliseconds to several seconds without adjusting the brightness of laser displays. The speckle contrast of raster-scanned mobile projector without any speckle-reduction device was nearly constant over various exposure times. On the contrary to this, in full-frame projection type laser displays equipped with a temporally-averaging speckle-reduction device, some of their speckle contrasts close to the lower limits noise were slightly increased at the shorter exposure time due to the noise. As a result, the exposure-time effect of speckle contrast could not be observed in our measurements, although it is more reasonable to think that the speckle contrasts of laser displays, which are equipped with the temporally-averaging speckle-reduction device, are dependent on the exposure time. This discrepancy may be attributed to the underestimation of temporal averaging factor. We expected that this method is useful for evaluating various laser displays and clarify the relationship between the speckle noise and the exposure time for a further verification of speckle reduction.

Exposure estimates to disinfection by-products of chlorinated drinking water.

PubMed

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

1999-02-01

Exposure to disinfection by-products (DBPs) of drinking water is multiroute and occurs in households serviced by municipal water treatment facilities that disinfect the water as a necessary step to halt the spread of waterborne infectious diseases. Biomarkers of the two most abundant groups of DBPs of chlorination, exhaled breath levels of trihalomethanes (THMs) and urinary levels of two haloacetic acids, were compared to exposure estimates calculated from in-home tap water concentrations and responses to a questionnaire related to water usage. Background THM breath concentrations were uniformly low. Strong relationships were identified between the THM breath concentrations collected after a shower and both the THM water concentration and the THM exposure from a shower, after adjusting for the postshower delay time in collecting the breath sample. Urinary haloacetic acid excretion rates were not correlated to water concentrations. Urinary trichloroacetic acid excretion rates were correlated with ingestion exposure, and that correlation was stronger in a subset of individuals who consumed beverages primarily within their home where the concentration measurements were made. No correlation was observed between an average 48-hr exposure estimate and the urinary dichloroacetic acid excretion rate, presumably because of its short biological half-life. Valid biomarkers were identified for DBP exposures, but the time between the exposure and sample collection should be considered to account for different metabolic rates among the DBPs. Further, using water concentration as an exposure estimate can introduce misclassification of exposure for DBPs whose primary route is ingestion due to the great variability in the amount of water ingested across a population.

Long-term exposure of rat pancreatic islets to fatty acids inhibits glucose-induced insulin secretion and biosynthesis through a glucose fatty acid cycle.

PubMed Central

Zhou, Y P; Grill, V E

1994-01-01

We tested effects of long-term exposure of pancreatic islets to free fatty acids (FFA) in vitro on B cell function. Islets isolated from male Sprague-Dawley rats were exposed to palmitate (0.125 or 0.25 mM), oleate (0.125 mM), or octanoate (2.0 mM) during culture. Insulin responses were subsequently tested in the absence of FFA. After a 48-h exposure to FFA, insulin secretion during basal glucose (3.3 mM) was several-fold increased. However, during stimulation with 27 mM glucose, secretion was inhibited by 30-50% and proinsulin biosynthesis by 30-40%. Total protein synthesis was similarly affected. Conversely, previous palmitate did not impair alpha-ketoisocaproic acid (5 mM)-induced insulin release. Induction and reversibility of the inhibitory effect on glucose-induced insulin secretion required between 6 and 24 h. Addition of the carnitine palmitoyltransferase I inhibitor etomoxir (1 microM) partially reversed (by > 50%) FFA-associated decrease in secretory as well as proinsulin biosynthetic responses to 27 mM glucose. The inhibitory effect of previous palmitate was similar when co-culture was performed with 5.5, 11, or 27 mM glucose. Exposure to palmitate or oleate reduced the production of 14CO2 from D-[U-14C]glucose, and of 14CO2 from D-[3,4-14C]-glucose, both effects being reversed by etomoxir. Conclusions: long-term exposure to FFA inhibits glucose-induced insulin secretion and biosynthesis probably through a glucose fatty acid cycle. PMID:8113418

Escherichia albertii Inactivation following l-Lactic Acid Exposure or Cooking in Ground Beef.

PubMed

Jones-Ibarra, Amie M; Wall, Kayley R; Vuia-Riser, Jennifer; Kerth, Chris R; Castillo, Alejandro; Taylor, T Matthew

2016-09-01

Escherichia albertii is an emerging foodborne pathogen recovered from young children and adults exhibiting symptoms of gastroenteritis via pathogenesis factors including attaching and effacing lesions, cytolethal distending toxin, and Shiga toxin variants. Study objectives were to determine E. albertii survival following (i) exposure to lactic acid as a function of solution pH and incubation period and (ii) cooking ground beef patties to different endpoint temperatures. E. albertii was incubated in phosphate buffer containing 3.0% l-lactic acid adjusted to pH 3.0, 4.0, 5.0, or 7.0; survivors were determined every 30 min for 150 min. Ground beef patties (80% lean) were cooked to temperature endpoints simulating undercooking (62°C), the minimum temperature for safe cooking (71.1°C), and cooking to well done (76°C). Maximal pathogen reduction was observed after a 30-min exposure to pH 3.0 l-lactic acid. Reductions of 3.9, 4.4, and 4.9 log CFU/g were obtained following cooking ground beef patties to 62, 71.1, and 76°C, respectively, but the reductions did not differ as a function of the endpoint cooking temperature (P ≥ 0.05). E. albertii may be controlled on beef through the proper application of antimicrobial interventions and cooking.

Suppression of glycosaminoglycan synthesis by articular cartilage, but not of hyaluronic acid synthesis by synovium, after exposure to radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hugenberg, S.T.; Myers, S.L.; Brandt, K.D.

1989-04-01

We recently found that injection of 2 mCi of yttrium 90 (90Y; approximately 23,000 rads) into normal canine knees stimulated glycosaminoglycan (GAG) synthesis by femoral condylar cartilage. The present investigation was conducted to determine whether radiation affects cartilage metabolism directly. Rates of GAG synthesis and degradation in normal canine articular cartilage were studied following irradiation. Cultured synovium from the same knees was treated similarly, to determine the effects of irradiation on hyaluronic acid synthesis. Twenty-four hours after exposure to 1,000 rads, 10,000 rads, or 50,000 rads, 35S-GAG synthesis by the cartilage was 93%, 69%, and 37%, respectively, of that inmore » control, nonirradiated cartilage. The effect was not rapidly reversible: 120 hours after exposure to 50,000 rads, GAG synthesis remained at only 28% of the control level. Autoradiography showed marked suppression of 35S uptake by chondrocytes after irradiation. Cartilage GAG degradation was also increased following irradiation: 4 hours and 8 hours after exposure to 50,000 rads, the cartilage GAG concentration was only 66% and 54%, respectively, of that at time 0, while corresponding values for control, nonirradiated cartilage were 90% and 87%. In contrast to its effects on cartilage GAG metabolism, radiation at these levels had no effect on synovial hyaluronic acid synthesis.« less

Real-time Measurements of Amino Acid and Protein Hydroperoxides Using Coumarin Boronic Acid*

PubMed Central

Michalski, Radoslaw; Zielonka, Jacek; Gapys, Ewa; Marcinek, Andrzej; Joseph, Joy; Kalyanaraman, Balaraman

2014-01-01

Hydroperoxides of amino acid and amino acid residues (tyrosine, cysteine, tryptophan, and histidine) in proteins are formed during oxidative modification induced by reactive oxygen species. Amino acid hydroperoxides are unstable intermediates that can further propagate oxidative damage in proteins. The existing assays (oxidation of ferrous cation and iodometric assays) cannot be used in real-time measurements. In this study, we show that the profluorescent coumarin boronic acid (CBA) probe reacts with amino acid and protein hydroperoxides to form the corresponding fluorescent product, 7-hydroxycoumarin. 7-Hydroxycoumarin formation was catalase-independent. Based on this observation, we have developed a fluorometric, real-time assay that is adapted to a multiwell plate format. This is the first report showing real-time monitoring of amino acid and protein hydroperoxides using the CBA-based assay. This approach was used to detect protein hydroperoxides in cell lysates obtained from macrophages exposed to visible light and photosensitizer (rose bengal). We also measured the rate constants for the reaction between amino acid hydroperoxides (tyrosyl, tryptophan, and histidine hydroperoxides) and CBA, and these values (7–23 m−1 s−1) were significantly higher than that measured for H2O2 (1.5 m−1 s−1). Using the CBA-based competition kinetics approach, the rate constants for amino acid hydroperoxides with ebselen, a glutathione peroxidase mimic, were also determined, and the values were within the range of 1.1–1.5 × 103 m−1 s−1. Both ebselen and boronates may be used as small molecule scavengers of amino acid and protein hydroperoxides. Here we also show formation of tryptophan hydroperoxide from tryptophan exposed to co-generated fluxes of nitric oxide and superoxide. This observation reveals a new mechanism for amino acid and protein hydroperoxide formation in biological systems. PMID:24928516

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 (10 mg/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. Copyright © 2015 Elsevier B.V. All rights reserved.

Geographical Differences in Dietary Exposure to Perfluoroalkyl Acids between Manufacturing and Application Regions in China.

PubMed

Zhang, Haiyan; Vestergren, Robin; Wang, Thanh; Yu, Junchao; Jiang, Guibin; Herzke, Dorte

2017-05-16

Emissions of perfluoroalkyl acids (PFAAs) have increased in China over the past decade, but human exposure pathways are poorly understood. Here we analyzed 15 PFAAs in commonly consumed food items and calculated body weight normalized dietary intake rates (estimated dietary intake, EDIs) in an area with ongoing PFAA production (Hubei province; n = 121) and an urbanized coastal area (Zhejiang province; n = 106). Geographical differences in concentrations were primarily observed for perfluorooctanesulfonic acid (PFOS) and perfluorohexanesulfonic acid (PFHxS) in animal food items and short-chain PFAAs in vegetable food items. The average EDI of ∑PFAAs for adults in Hubei (998 ng kg -1 day -1 ) was more than 2 orders of magnitude higher than that in Zhejiang (9.03 ng kg -1 day -1 ). In Hubei province, the average EDI of PFOS for adults (87 ng kg -1 day -1 ) was close to or exceeded advisory guidelines used in other countries indicating health risks for the population from long-term exposure. Yet, PFOS could only account for about 10% of the EDI of ∑PFAAs in the Hubei province, which was dominated by short-chain PFAAs through consumption of vegetables. The large contribution of short-chain PFAAs to the total EDIs in manufacturing areas emphasize the need for improved exposure and hazard assessment tools of these substances.

Alginate antacid (Gaviscon DA) chewable tablets reduce esophageal acid exposure in Chinese patients with gastroesophageal reflux disease and heartburn symptoms.

PubMed

Yuan, Yao Zong; Fang, Jing Yuan; Zou, Duo Wu; Levinson, Nigel; Jenner, Bartosz; Wilkinson, Joanne

2016-11-01

To assess the efficacy of Gaviscon Double Action (DA) alginate antacid chewable tablets for reducing esophageal acid exposure in Chinese patients with gastroesophageal reflux disease (GERD). Altogether 44 patients reporting moderate to severe heartburn symptoms underwent two pH monitoring visits. The treatment sequence was randomized to patients received DA alginate antacid or placebo at one visit and the alternate treatment 7 days later. After a standardized reflux-provoking meal, patients took four tablets of DA alginate antacid or placebo. Esophageal pH was measured for 4 h post-dosing using an electrode positioned 5 cm above the lower esophageal sphincter. The primary end-point was the percentage of 4-h post-dosing period with pH <4. Secondary end-points were number of acid reflux episodes (pH <4), longest reflux time and DeMeester scores. All 44 patients completed the study and provided data for analysis. With DA alginate antacid, the mean percentage time with pH <4 was 5.1%, significantly less (P = 0.0003) than with placebo (14.8%). DA alginate antacid was statistically significantly superior (P = 0.0290) to placebo (from at least twofold to threefold better) for all other end-points. Two patients reported two mild adverse events (AEs) that resolved within a month of completing the study. No patients had serious and/or severe AEs and none withdrew due to AEs. DA alginate antacid was statistically significantly superior to placebo in reducing post-prandial acid exposure without serious clinically relevant health risks. These findings suggest DA alginate antacid tablets are appropriate for treating acid reflux in Chinese GERD patients with heartburn symptoms. © 2016 Chinese Medical Association Shanghai Branch, Chinese Society of Gastroenterology, Renji Hospital Affiliated to Shanghai Jiaotong University School of Medicine and John Wiley & Sons Australia, Ltd.

Amino acid and glucose uptake by rat brown adipose tissue. Effect of cold-exposure and acclimation.

PubMed Central

López-Soriano, F J; Fernández-López, J A; Mampel, T; Villarroya, F; Iglesias, R; Alemany, M

1988-01-01

The net uptake/release of glucose, lactate and amino acids from the bloodstream by the interscapular brown adipose tissue of control, cold-exposed and cold-acclimated rats was estimated by measurement of arteriovenous differences in their concentrations. In the control animals amino acids contributed little to the overall energetic needs of the tissue; glucose uptake was more than compensated by lactate efflux. Cold-exposure resulted in an enhancement of amino acid utilization and of glucose uptake, with high lactate efflux. There was a net glycine and proline efflux that partly compensated the positive nitrogen balance of the tissue; amino acids accounted for about one-third of the energy supplied by glucose to the tissue. Cold-acclimation resulted in a very high increase in glucose uptake, with a parallel decrease in lactate efflux and amino acid consumption. Branched-chain amino acids, however, were more actively utilized. This was related with a much higher alanine efflux, in addition to that of glycine and proline. It is suggested that most of the glucose used during cold-exposure is returned to the bloodstream as lactate under conditions of active lipid utilization, amino acids contributing their skeletons largely in anaplerotic pathways. On the other hand, cold-acclimation resulted in an important enhancement of glucose utilization, with lowered amino acid oxidation. Amino acids are thus used as metabolic substrates by the brown adipose tissue of rats under conditions of relatively scarce substrate availability, but mainly as anaplerotic substrates, in parallel to glucose. Cold-acclimation results in a shift of the main substrates used in thermogenesis from lipid to glucose, with a much lower need for amino acids. PMID:3421924

Color stability of CAD/CAM Zirconia ceramics following exposure to acidic and staining drinks.

PubMed

Colombo, Marco; Cavallo, Marco; Miegge, Matteo; Dagna, Alberto; Beltrami, Riccardo; Chiesa, Marco; Poggio, Claudio

2017-11-01

The aim of this in vitro study was to evaluate the color stability of CAD/CAM Zirconia ceramics following exposure to acidic drink (Coca Cola) and after exposure to staining solution (coffee). All the samples were immersed in different staining solutions over a 28-day test period. A colorimetric evaluation according to the CIE L*a*b* system was performed by a blind trained operator at 7, 14, 21, 28 days of the staining process. Shapiro Wilk test and Kruskal-Wallis ANOVA were applied to assess significant differences among restorative materials. Paired t-test was applied to test which CIE L*a*b* parameters significantly changed after immersion in staining solutions. One week immersion in acidic drink did not cause a perceivable discoloration for all restorative materials (ΔE < 3.3). Subsequent immersion in coffee affected color stability of all Zirconia samples, even if Kruskal-Wallis ANOVA found significant differences among the various restorative materials. The ∆Es of CAD/CAM Zirconia ceramics after immersion in coffee varied among the products, but color integrity is not affected by contact with acidic drinks. Key words: CAD/CAM restorative materials, CIE Lab, Zirconia ceramics.

Exposure to Sub-lethal 2,4-Dichlorophenoxyacetic Acid Arrests Cell Division and Alters Cell Surface Properties in Escherichia coli.

PubMed

Bhat, Supriya V; Kamencic, Belma; Körnig, André; Shahina, Zinnat; Dahms, Tanya E S

2018-01-01

Escherichia coli is a robust, easily adaptable and culturable bacterium in vitro , and a model bacterium for studying the impact of xenobiotics in the environment. We have used correlative atomic force - laser scanning confocal microscopy (AFM-LSCM) to characterize the mechanisms of cellular response to the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). One of the most extensively used herbicides world-wide, 2,4-D is known to cause hazardous effects in diverse non-target organisms. Sub-lethal concentrations of 2,4-D caused DNA damage in E. coli WM1074 during short exposure periods which increased significantly over time. In response to 2,4-D, FtsZ and FtsA relocalized within seconds, coinciding with the complete inhibition of cell septation and cell elongation. Exposure to 2,4-D also resulted in increased activation of the SOS response. Changes to cell division were accompanied by concomitant changes to surface roughness, elasticity and adhesion in a time-dependent manner. This is the first study describing the mechanistic details of 2,4-D at sub-lethal levels in bacteria. Our study suggests that 2,4-D arrests E. coli cell division within seconds after exposure by disrupting the divisome complex, facilitated by dissipation of membrane potential. Over longer exposures, 2,4-D causes filamentation as a result of an SOS response to oxidative stress induced DNA damage.

Exposure to Sub-lethal 2,4-Dichlorophenoxyacetic Acid Arrests Cell Division and Alters Cell Surface Properties in Escherichia coli

PubMed Central

Bhat, Supriya V.; Kamencic, Belma; Körnig, André; Shahina, Zinnat; Dahms, Tanya E. S.

2018-01-01

Escherichia coli is a robust, easily adaptable and culturable bacterium in vitro, and a model bacterium for studying the impact of xenobiotics in the environment. We have used correlative atomic force – laser scanning confocal microscopy (AFM-LSCM) to characterize the mechanisms of cellular response to the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). One of the most extensively used herbicides world-wide, 2,4-D is known to cause hazardous effects in diverse non-target organisms. Sub-lethal concentrations of 2,4-D caused DNA damage in E. coli WM1074 during short exposure periods which increased significantly over time. In response to 2,4-D, FtsZ and FtsA relocalized within seconds, coinciding with the complete inhibition of cell septation and cell elongation. Exposure to 2,4-D also resulted in increased activation of the SOS response. Changes to cell division were accompanied by concomitant changes to surface roughness, elasticity and adhesion in a time-dependent manner. This is the first study describing the mechanistic details of 2,4-D at sub-lethal levels in bacteria. Our study suggests that 2,4-D arrests E. coli cell division within seconds after exposure by disrupting the divisome complex, facilitated by dissipation of membrane potential. Over longer exposures, 2,4-D causes filamentation as a result of an SOS response to oxidative stress induced DNA damage. PMID:29472899

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.

Effect of Exposure to Atmospheric Ultrafine Particles on Production of Free Fatty Acids and Lipid Metabolites in the Mouse Small Intestine

PubMed Central

Li, Rongsong; Navab, Kaveh; Hough, Greg; Daher, Nancy; Zhang, Min; Mittelstein, David; Lee, Katherine; Pakbin, Payam; Saffari, Arian; Bhetraratana, May; Sulaiman, Dawoud; Beebe, Tyler; Wu, Lan; Jen, Nelson; Wine, Eytan; Tseng, Chi-Hong; Araujo, Jesus A.; Fogelman, Alan; Sioutas, Constantinos; Navab, Mohamed

2014-01-01

Background: Exposure to ambient ultrafine particulate matter (UFP) is a well-recognized risk factor for cardiovascular and respiratory diseases. However, little is known about the effects of air pollution on gastrointestinal disorders. Objective: We sought to assess whether exposure to ambient UFP (diameter < 180 nm) increased free fatty acids and lipid metabolites in the mouse small intestine. Methods: Ldlr-null mice were exposed to filtered air (FA) or UFP collected at an urban Los Angeles, California, site that was heavily affected by vehicular emissions; the exposure was carried out for 10 weeks in the presence or absence of D-4F, an apolipoprotein A-I mimetic peptide with antioxidant and anti-inflammation properties on a high-fat or normal chow diet. Results: Compared with FA, exposure to UFP significantly increased intestinal hydroxyeicosatetraenoic acids (HETEs), including 15-HETE, 12-HETE, 5-HETE, as well as hydroxyoctadecadienoic acids (HODEs), including 13-HODE and 9-HODE. Arachidonic acid (AA) and prostaglandin D2 (PGD2) as well as some of the lysophosphatidic acids (LPA) in the small intestine were also increased in response to UFP exposure. Administration of D-4F significantly reduced UFP-mediated increase in HETEs, HODEs, AA, PGD2, and LPA. Although exposure to UFP further led to shortened villus length accompanied by prominent macrophage and neutrophil infiltration into the intestinal villi, administration of D-4F mitigated macrophage infiltration. Conclusions: Exposure to UFP promotes lipid metabolism, villus shortening, and inflammatory responses in mouse small intestine, whereas administration of D-4F attenuated these effects. Our findings provide a basis to further assess the mechanisms underlying UFP-mediated lipid metabolism in the digestive system with clinical relevance to gut homeostasis and diseases. Citation: Li R, Navab K, Hough G, Daher N, Zhang M, Mittelstein D, Lee K, Pakbin P, Saffari A, Bhetraratana M, Sulaiman D, Beebe T, Wu L, Jen

Dose–response assessment of nephrotoxicity from a twenty-eight-day combined-exposure to melamine and cyanuric acid in F344 rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gamboa da Costa, Gonçalo, E-mail: goncalo.gamboa@fda.hhs.gov; Jacob, Cristina C.; Von Tungeln, Linda S.

The adulteration of pet food with melamine and derivatives, including cyanuric acid, has been implicated in the kidney failure and death of cats and dogs in the USA and other countries. In a previous 7-day dietary study in F344 rats, we established a no-observed-adverse-effect level (NOAEL) for a co-exposure to melamine and cyanuric acid of 8.6 mg/kg bw/day of each compound, and a benchmark dose lower confidence limit (BMDL) of 8.4–10.9 mg/kg bw/day of each compound. To ascertain the role played by the duration of exposure, we treated F344 rats for 28 days. Groups of male and female rats weremore » fed diet containing 0 (control), 30, 60, 120, 180, 240, or 360 ppm of both melamine and cyanuric acid. The lowest dose that produced histopathological alterations in the kidney was 120 ppm, versus 229 ppm in the 7-day study. Wet-mount analysis of kidney sections demonstrated the formation of melamine cyanurate spherulites in one male and two female rats at the 60 ppm dose and in one female rat at the 30 ppm dose, establishing a NOAEL of 2.1 mg/kg bw/day for males and < 2.6 mg/kg bw/day for females, and BMDL values as low as 1.6 mg/kg bw/day for both sexes. These data demonstrate that the length of exposure is an important component in the threshold of toxicity from a co-exposure to these compounds and suggest that the current risk assessments based on exposures to melamine alone may not reflect sufficiently the risk of a co-exposure to melamine and cyanuric acid. -- Highlights: ► A 28-day dietary co-exposure to melamine and cyanuric acid was conducted in F344 rats. ► The NOAELs were 2.1 mg/kg bw/day for males and < 2.6 mg/kg bw/day for females. ► BMDL values as low as 1.6 mg/kg bw/day for both sexes were determined. ► The length of exposure plays an important role in the threshold of toxicity. ► Current assessments may underestimate the risk of melamine and cyanuric acid.« less

Combined Prenatal Pesticide Exposure and Folic Acid Intake in Relation to Autism Spectrum Disorder.

PubMed

Schmidt, Rebecca J; Kogan, Vladimir; Shelton, Janie F; Delwiche, Lora; Hansen, Robin L; Ozonoff, Sally; Ma, Claudia C; McCanlies, Erin C; Bennett, Deborah H; Hertz-Picciotto, Irva; Tancredi, Daniel J; Volk, Heather E

2017-09-08

Maternal folic acid (FA) protects against developmental toxicity from certain environmental chemicals. We examined combined exposures to maternal FA and pesticides in relation to autism spectrum disorder (ASD). Participants were California children born from 2000-2007 who were enrolled in the Childhood Autism Risks from Genetics and the Environment (CHARGE) case-control study at age 2-5 y, were clinically confirmed to have ASD (n=296) or typical development (n=220), and had information on maternal supplemental FA and pesticide exposures. Maternal supplemental FA and household pesticide product use were retrospectively collected in telephone interviews from 2003-2011. High vs. low daily FA intake was dichotomized at 800μg (median). Mothers' addresses were linked to a statewide database of commercial applications to estimate agricultural pesticide exposure. High FA intake (≥800μg) during the first pregnancy month and no known pesticide exposure was the reference group for all analyses. Compared with this group, ASD was increased in association with <800μg FA and any indoor pesticide exposure {adjusted odds ratio [OR]=2.5 [95% confidence interval (CI): 1.3, 4.7]} compared with low FA [OR=1.2 (95% CI: 0.7, 2.2)] or indoor pesticides [OR=1.7 (95% CI: 1.1, 2.8)] alone. ORs for the combination of low FA and regular pregnancy exposure (≥6 mo) to pet pesticides or to outdoor sprays and foggers were 3.9 (95% CI: 1.4, 11.5) and 4.1 (95% CI: 1.7, 10.1), respectively. ORs for low maternal FA and agricultural pesticide exposure 3 mo before or after conception were 2.2 (95% CI: 0.7, 6.5) for chlorpyrifos, 2.3 (95% CI: 0.98, 5.3) for organophosphates, 2.1 (95% CI: 0.9, 4.8) for pyrethroids, and 1.5 (95% CI: 0.5, 4.8) for carbamates. Except for carbamates, these ORs were approximately two times greater than those for either exposure alone or for the expected ORs for combined exposures under multiplicative or additive models. In this study population, associations between

Combined Prenatal Pesticide Exposure and Folic Acid Intake in Relation to Autism Spectrum Disorder

PubMed Central

Kogan, Vladimir; Shelton, Janie F.; Delwiche, Lora; Hansen, Robin L.; Ozonoff, Sally; Ma, Claudia C.; McCanlies, Erin C.; Bennett, Deborah H.; Hertz-Picciotto, Irva; Tancredi, Daniel J.; Volk, Heather E.

2017-01-01

Background: Maternal folic acid (FA) protects against developmental toxicity from certain environmental chemicals. Objective: We examined combined exposures to maternal FA and pesticides in relation to autism spectrum disorder (ASD). Methods: Participants were California children born from 2000–2007 who were enrolled in the Childhood Autism Risks from Genetics and the Environment (CHARGE) case–control study at age 2–5 y, were clinically confirmed to have ASD (n=296) or typical development (n=220), and had information on maternal supplemental FA and pesticide exposures. Maternal supplemental FA and household pesticide product use were retrospectively collected in telephone interviews from 2003–2011. High vs. low daily FA intake was dichotomized at 800μg (median). Mothers’ addresses were linked to a statewide database of commercial applications to estimate agricultural pesticide exposure. Results: High FA intake (≥800μg) during the first pregnancy month and no known pesticide exposure was the reference group for all analyses. Compared with this group, ASD was increased in association with <800μg FA and any indoor pesticide exposure {adjusted odds ratio [OR]=2.5 [95% confidence interval (CI): 1.3, 4.7]} compared with low FA [OR=1.2 (95% CI: 0.7, 2.2)] or indoor pesticides [OR=1.7 (95% CI: 1.1, 2.8)] alone. ORs for the combination of low FA and regular pregnancy exposure (≥6 mo) to pet pesticides or to outdoor sprays and foggers were 3.9 (95% CI: 1.4, 11.5) and 4.1 (95% CI: 1.7, 10.1), respectively. ORs for low maternal FA and agricultural pesticide exposure 3 mo before or after conception were 2.2 (95% CI: 0.7, 6.5) for chlorpyrifos, 2.3 (95% CI: 0.98, 5.3) for organophosphates, 2.1 (95% CI: 0.9, 4.8) for pyrethroids, and 1.5 (95% CI: 0.5, 4.8) for carbamates. Except for carbamates, these ORs were approximately two times greater than those for either exposure alone or for the expected ORs for combined exposures under multiplicative or additive

Exposure estimates to disinfection by-products of chlorinated drinking water.

PubMed Central

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

1999-01-01

Exposure to disinfection by-products (DBPs) of drinking water is multiroute and occurs in households serviced by municipal water treatment facilities that disinfect the water as a necessary step to halt the spread of waterborne infectious diseases. Biomarkers of the two most abundant groups of DBPs of chlorination, exhaled breath levels of trihalomethanes (THMs) and urinary levels of two haloacetic acids, were compared to exposure estimates calculated from in-home tap water concentrations and responses to a questionnaire related to water usage. Background THM breath concentrations were uniformly low. Strong relationships were identified between the THM breath concentrations collected after a shower and both the THM water concentration and the THM exposure from a shower, after adjusting for the postshower delay time in collecting the breath sample. Urinary haloacetic acid excretion rates were not correlated to water concentrations. Urinary trichloroacetic acid excretion rates were correlated with ingestion exposure, and that correlation was stronger in a subset of individuals who consumed beverages primarily within their home where the concentration measurements were made. No correlation was observed between an average 48-hr exposure estimate and the urinary dichloroacetic acid excretion rate, presumably because of its short biological half-life. Valid biomarkers were identified for DBP exposures, but the time between the exposure and sample collection should be considered to account for different metabolic rates among the DBPs. Further, using water concentration as an exposure estimate can introduce misclassification of exposure for DBPs whose primary route is ingestion due to the great variability in the amount of water ingested across a population. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 PMID:9924004

Does oxygen exposure time control the extent of organic matter decomposition in peatlands?

NASA Astrophysics Data System (ADS)

Philben, Michael; Kaiser, Karl; Benner, Ronald

2014-05-01

The extent of peat decomposition was investigated in four cores collected along a latitudinal gradient from 56°N to 66°N in the West Siberian Lowland. The acid:aldehyde ratios of lignin phenols were significantly higher in the two northern cores compared with the two southern cores, indicating peats at the northern sites were more highly decomposed. Yields of hydroxyproline, an amino acid found in plant structural glycoproteins, were also significantly higher in northern cores compared with southern cores. Hydroxyproline-rich glycoproteins are not synthesized by microbes and are generally less reactive than bulk plant carbon, so elevated yields indicated that northern cores were more extensively decomposed than the southern cores. The southern cores experienced warmer temperatures, but were less decomposed, indicating that temperature was not the primary control of peat decomposition. The plant community oscillated between Sphagnum and vascular plant dominance in the southern cores, but vegetation type did not appear to affect the extent of decomposition. Oxygen exposure time appeared to be the strongest control of the extent of peat decomposition. The northern cores had lower accumulation rates and drier conditions, so these peats were exposed to oxic conditions for a longer time before burial in the catotelm, where anoxic conditions prevail and rates of decomposition are generally lower by an order of magnitude.

Effect of time of day and duration into shift on hazardous exposures to biological fluids.

PubMed

Macias, D J; Hafner, J; Brillman, J C; Tandberg, D

1996-06-01

To determine whether hospital employee biological hazardous exposure rates varied with time of day or increased with time interval into shift. This was a retrospective occurrence report review conducted at a university hospital with an emergency medicine residency program. Health care worker biological hazardous exposure data over a 30-month period were reviewed. Professional status, date, time, and type of exposure (needlestick, laceration, splash), time interval into shift of exposure, and hospital location of exposure were recorded. Hourly employee counts and risky procedure counts were matched by location with each reported exposure, to determine hourly rates of biological hazardous exposures. Analysis of 411 recorded exposures demonstrated that more people were exposed between 9:00 AM and 11:00 AM (p < 0.05), yet the exposure risk did not vary significantly when expressed as the number of exposures per worker or per procedure. Of the 393 exposures with data describing time interval into shift when the exposure occurred, significant numbers of exposures occurred during the first hour and at shift's end [when corrected for exposures per worker (p < 0.05) or exposures per procedure (p < 0.05)]. While the number of exposures are increased in the AM hours, the exposure rate (as a function of workers or procedures) does not vary with time of the day. However, the exposure rate is increased during the first hour and last 2 hours of a shift. Efforts to increase worker precautions at the beginning and end of shifts are warranted.

The occurrence, exposure and risk assessment of perfluoroalkyl acids in food from mainland, China.

PubMed

Wang, Xinxuan; Zhang, Ruobing; Zhang, Hong; Wang, Yanping

2017-11-01

To study the contamination of perfluoroalkyl acids (PFAAs) in Chinese food and the risk of dietary exposure for the Chinese population, the data of 17 PFAAs covering 38 cities throughout China in 15 groups of foods were collected for meta-analysis from published and available research literature. Using food consumption and body weight parameters, estimated dietary intakes (EDIs) were calculated for evaluation using the Scenario-Based Risk Assessment (SceBRA) modelling. Among food groups, the highest ΣPFAAs concentrations and EDI contributions were both found in poultry (363 ng/g), fish and shrimp (313 ng/g), dark vegetables (309 ng/g), fruits (116 ng/g) and pork (25 ng/g). The EDI of adults in the high-exposure scenario was about twice that of the intermediate-exposure scenario, while the EDI of children was about twice that of adults' EDI in the intermediate-exposure scenario. In addition, the PFOS EDI for children under high exposure approached its tolerable daily intake (TDI). Therefore high dietary exposure to PFAAs is giving rise to an increased health risk, especially for children.

Gastroesophageal pressure gradients in gastroesophageal reflux disease: relations with hiatal hernia, body mass index, and esophageal acid exposure.

PubMed

de Vries, Durk R; van Herwaarden, Margot A; Smout, André J P M; Samsom, Melvin

2008-06-01

The roles of intragastric pressure (IGP), intraesophageal pressure (IEP), gastroesophageal pressure gradient (GEPG), and body mass index (BMI) in the pathophysiology of gastroesophageal reflux disease (GERD) and hiatal hernia (HH) are only partly understood. In total, 149 GERD patients underwent stationary esophageal manometry, 24-h pH-metry, and endoscopy. One hundred three patients had HH. Linear regression analysis showed that each kilogram per square meter of BMI caused a 0.047-kPa increase in inspiratory IGP (95% confidence interval [CI] 0.026-0.067) and a 0.031-kPa increase in inspiratory GEPG (95% CI 0.007-0.055). Each kilogram per square meter of BMI caused expiratory IGP to increase with 0.043 kPa (95% CI 0.025-0.060) and expiratory IEP with 0.052 kPa (95% CI 0.027-0.077). Each added year of age caused inspiratory IEP to decrease by 0.008 kPa (95% CI -0.015-0.001) and inspiratory GEPG to increase by 0.008 kPa (95% CI 0.000-0.015). In binary logistic regression analysis, HH was predicted by inspiratory and expiratory IGP (odds ratio [OR] 2.93 and 2.62, respectively), inspiratory and expiratory GEPG (OR 3.19 and 2.68, respectively), and BMI (OR 1.72/5 kg/m(2)). In linear regression analysis, HH caused an average 5.09% increase in supine acid exposure (95% CI 0.96-9.22) and an average 3.46% increase in total acid exposure (95% CI 0.82-6.09). Each added year of age caused an average 0.10% increase in upright acid exposure and a 0.09% increase in total acid exposure (95% CI 0.00-0.20 and 0.00-0.18). BMI predicts IGP, inspiratory GEPG, and expiratory IEP. Age predicts inspiratory IEP and GEPG. Presence of HH is predicted by IGP, GEPG, and BMI. GEPG is not associated with acid exposure.

Occupational exposure to perfluoroalkyl substances and serum levels of perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in an aging population from upstate New York: a retrospective cohort study.

PubMed

Tanner, Eva M; Bloom, Michael S; Wu, Qian; Kannan, Kurunthachalam; Yucel, Recai M; Shrestha, Srishti; Fitzgerald, Edward F

2018-02-01

Perfluoroalkyl substances (PFASs) are environmentally persistent amphiphilic compounds. Exposure to two PFASs, perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) is linked to specific occupations and industries. This study examines the contribution of past occupational PFAS exposure to serum PFOS and PFOA levels among 154 older adults in New York State. Serum PFOS and PFOA levels were compared to data from the National Health and Nutrition Examination Survey (NHANES). Potential occupational exposure to any PFAS was determined from work histories, reviewed by an industrial hygienist, and assessed in relation to current serum PFOS and PFOA levels using exposure probability, duration and cumulative exposure. We observed 25% higher serum PFOS and 80% higher PFOA levels in study participants compared to NHANES. No participants reported PFAS chemical manufacturing work, but n = 68 reported work in occupations and industries known to use PFASs. We found that participants with high cumulative workplace exposure had 34% higher serum PFOS levels compared to participants without occupational exposure, adjusted for age, sex and income. Serum PFOS levels were 26% higher for participants with longer occupational exposure durations. The probability of occupational PFAS exposure metric was not associated with serum PFOS. Serum PFOA was not associated with any measure of occupational exposure. Occupational exposure may contribute to total PFOS body burden in this study population, even among workers not directly involved in manufacturing PFASs. PFAS exposure assessments should evaluate the workplace as a potential source, even when workplace exposures are assumed to be low or moderate.

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

Surgery for subacromial impingement syndrome in relation to intensities of occupational mechanical exposures across 10-year exposure time windows.

PubMed

Dalbøge, Annett; Frost, Poul; Andersen, Johan Hviid; Svendsen, Susanne Wulff

2018-03-01

We aimed to identify intensities of occupational mechanical exposures (force, arm elevation and repetition) that do not entail an increased risk of surgery for subacromial impingement syndrome (SIS) even after prolonged durations of exposure. Additionally, we wanted to evaluate if exposure to hand-arm vibration (HAV) is an independent risk factor. We used data from a register-based cohort study of the entire Danish working population (n=2 374 403). During follow-up (2003-2008), 14 118 first-time events of surgery for SIS occurred. For each person, we linked register-based occupational codes (1993-2007) to a general population job exposure matrix to obtain year-by-year exposure intensities on measurement scales for force, upper arm elevation >90° and repetition and expert rated intensities of exposure to HAV. For 10-year exposure time windows, we calculated the duration of exposure at specific intensities above minimal (low, medium and high). We used a logistic regression technique equivalent to discrete survival analysis adjusting for cumulative effects of other mechanical exposures. We found indications of safe exposure intensities for repetition (median angular velocity <45°/s), while force exertion ≥10% of maximal voluntary electrical activity and upper arm elevation >90° >2 min/day implied an increased risk reaching ORs of 1.7 and 1.5 after 10 years at low intensities. No associations were found for HAV. We found indications of safe exposure intensities for repetition. Any intensities of force and upper arm elevation >90° above minimal implied an increased risk across 10-year exposure time windows. No independent associations were found for HAV. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

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.

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. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Effect of time-activity adjustment on exposure assessment for traffic-related ultrafine particles

PubMed Central

Lane, Kevin J; Levy, Jonathan I; Scammell, Madeleine Kangsen; Patton, Allison P; Durant, John L; Mwamburi, Mkaya; Zamore, Wig; Brugge, Doug

2015-01-01

Exposures to ultrafine particles (<100 nm, estimated as particle number concentration, PNC) differ from ambient concentrations because of the spatial and temporal variability of both PNC and people. Our goal was to evaluate the influence of time-activity adjustment on exposure assignment and associations with blood biomarkers for a near-highway population. A regression model based on mobile monitoring and spatial and temporal variables was used to generate hourly ambient residential PNC for a full year for a subset of participants (n=140) in the Community Assessment of Freeway Exposure and Health study. We modified the ambient estimates for each hour using personal estimates of hourly time spent in five micro-environments (inside home, outside home, at work, commuting, other) as well as particle infiltration. Time-activity adjusted (TAA)-PNC values differed from residential ambient annual average (RAA)-PNC, with lower exposures predicted for participants who spent more time away from home. Employment status and distance to highway had a differential effect on TAA-PNC. We found associations of RAA-PNC with high sensitivity C-reactive protein and Interleukin-6, although exposure-response functions were non-monotonic. TAA-PNC associations had larger effect estimates and linear exposure-response functions. Our findings suggest that time-activity adjustment improves exposure assessment for air pollutants that vary greatly in space and time. PMID:25827314

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.

Health effects of acid aerosols on North American children: air pollution exposures.

PubMed

Spengler, J D; Koutrakis, P; Dockery, D W; Raizenne, M; Speizer, F E

1996-05-01

Air pollution measurements were conducted over a 1-year period in 24 North American communities participating in a respiratory health study. Ozone, particle strong acidity, sulfate, and mass (PM10 and PM2.1) were measured in all communities. In 20 of the communities, sulfur dioxide, ammonia, nitric acid, nitrous acid, and particulate nitrate were measured. The sampler was located centrally in the community whenever possible and samples were collected every other day. Concentrations of particle strong acidity, mass, sulfate, and ozone were highly correlated both in the region of the country defined as a high-sulfur source area and in the downwind transport regions. These regions of the eastern United States and southern Canada experienced the greatest particle strong acidity, sulfate, and particle mass concentrations during the spring and summer months (May-September). The particle strong acidity concentrations were highest in regions close to the high sulfur emission areas of the United States; that is, in the area immediately to the west of the Appalachian Plateau and west of the Allegheny Mountains (western Pennsylvania, eastern Ohio, and West Virginia) up through southern Ontario. The frequency of particle strong acidity events decreased with transport distance from the region of highest sulfur emissions. Low particle strong acidity and sulfates were found at the western and midwestern sites of both the United States and Canada. Substantial concentrations of nitric acid were found in two of the California sites as well as many sites in the northeastern portion of the United States. Sites selected for the epidemiologic study provide a range of annual mean particle strong acidity exposures from below the limit of detection to more than 50 nmol/m3.

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,...

Color stability of CAD/CAM Zirconia ceramics following exposure to acidic and staining drinks

PubMed Central

Colombo, Marco; Cavallo, Marco; Miegge, Matteo; Dagna, Alberto; Beltrami, Riccardo; Chiesa, Marco

2017-01-01

Background The aim of this in vitro study was to evaluate the color stability of CAD/CAM Zirconia ceramics following exposure to acidic drink (Coca Cola) and after exposure to staining solution (coffee). Material and Methods All the samples were immersed in different staining solutions over a 28-day test period. A colorimetric evaluation according to the CIE L*a*b* system was performed by a blind trained operator at 7, 14, 21, 28 days of the staining process. Shapiro Wilk test and Kruskal-Wallis ANOVA were applied to assess significant differences among restorative materials. Paired t-test was applied to test which CIE L*a*b* parameters significantly changed after immersion in staining solutions. Results One week immersion in acidic drink did not cause a perceivable discoloration for all restorative materials (ΔE < 3.3). Subsequent immersion in coffee affected color stability of all Zirconia samples, even if Kruskal-Wallis ANOVA found significant differences among the various restorative materials. Conclusions The ∆Es of CAD/CAM Zirconia ceramics after immersion in coffee varied among the products, but color integrity is not affected by contact with acidic drinks. Key words:CAD/CAM restorative materials, CIE Lab, Zirconia ceramics. PMID:29302281

Association of lead exposure, serum uric acid and parameters of renal function in Nigerian lead-exposed workers.

PubMed

Alasia, D D; Emem-Chioma, P C; Wokoma, F S

2010-10-01

The presence of hyperuricemia and renal function impairment, especially in the absence of urate stone formation is strongly suggestive of lead nephropathy. The evaluation of this association is essential in areas where lead exposure is still prevalent and uncontrolled. To determine the relationship between serum uric acid and renal function indices in lead-exposed workers. A cross-sectional study of 190 adults with occupational lead exposure and 80 adults (comparison group), matched for age and sex was performed in Port Harcourt, South-south Nigeria. Blood lead was used as the biomarker of lead exposure while serum urea, serum creatinine, urine albumin (using urine albumin:creatinine ratio), estimated glomerular filtration rate (GFR) and serum uric acid were the renal function indices measured. Occupationally lead-exposed subjects had a significantly (p = 0.008) higher mean±SD blood lead levels (50.37±24.58 μg/dL) than the comparison group (41.40±26.85). The mean±SD serum urea (8.6±2.3 mg/dL), creatinine (1.0±0.2 mg/dL) and serum uric acid (4.6±1.2 mg/dL) were significantly (p < 0.01) higher in the study subjects than the comparison group (7.6±2.4, 0.9±0.2, and 3.9±1.1 mg/dL, respectively). The mean±SD creatinine clearance was significantly (p = 0.002) lower in the study subjects than the comparison group (98.9±21.3 vs. 108.2±25.2 mL/min/1.72 m2). Serum uric acid level correlated positively with serum creatinine (r = 0.134) and negatively with GFR (r = -0.151). People with occupational lead exposure are at risk of developing hyperuricemia and renal impairment.

Element uptake and physiological responses of Lactuca sativa upon co-exposures to tourmaline and dissolved humic acids.

PubMed

Jia, Weili; Wang, Cuiping; Ma, Chuanxin; Wang, Jicheng; Sun, Hongwen

2018-06-01

Element migration and physiological response in Lactuca sativa upon co-exposure to tourmaline (T) and dissolved humic acids (DHAs) were investigated. Different fractions of DHA 1 and DHA 4 and three different doses of T were introduced into Hoagland's solution. The results indicated that T enhanced the contents of elements such as N and C, Si and Al in the roots and shoots. The correlation between TF values of Si and Al (R 2  = 0.7387) was higher than that of Si and Mn (R 2  = 0.4961) without the presence of DHAs. However, both DHA 1 and DHA 4 increased the correlation between Si and Mn, but decreased the one between Si and Al. CAT activities in T treatments were positively correlated to the contents of N and Al in the shoots, whose R 2 was 0.9994 and 0.9897, respectively. In the co-exposure of DHAs and tourmaline, DHA 4 exhibited more impacts on element uptake, CAT activities, as well as ABA contents in comparison with the presence of DHA 1 , regardless of the T exposure doses. These results suggested that DHAs have effects on mineral element behaviors and physiological response in Lactuca sativa upon exposure to tourmaline for the first time, which had great use in guiding soil remediation.

IDENTIFICATION OF TIME-INTEGRATED SAMPLING AND MEASUREMENT TECHNIQUES TO SUPPORT HUMAN EXPOSURE STUDIES

EPA Science Inventory

Accurate exposure classification tools are required to link exposure with health effects in epidemiological studies. Long-term, time-integrated exposure measures would be desirable to address the problem of developing appropriate residential childhood exposure classifications. ...

Assessing the Impact of Exposure Time and Incapacitation on Longitudinal Trajectories of Criminal Offending.

ERIC Educational Resources Information Center

Piquero, Alex; Blumstein, Alfred; Brame, Robert; Haapanen, Rudy; Mulvey, Edward P.; Nagin, Daniel S.

2001-01-01

Examined effect of accounting for exposure (incarceration) time on arrest rate of 272 paroled serious offenders followed through age 33. Analysis without exposure time adjustments suggested that over 92 percent exhibited highest arrest activity in late teens and early 20s. Adjusted for exposure time, about 72 percent showed a decline in arrest…

Personal exposure of dairy workers to dust, endotoxin, muramic acid, ergosterol, and ammonia on large-scale dairies in the high plains Western United States.

PubMed

Davidson, Margaret E; Schaeffer, Joshua; Clark, Maggie L; Magzamen, Sheryl; Brooks, Elizabeth J; Keefe, Thomas J; Bradford, Mary; Roman-Muniz, Noa; Mehaffy, John; Dooley, Gregory; Poole, Jill A; Mitloehner, Frank M; Reed, Sue; Schenker, Marc B; Reynolds, Stephen J

2018-03-01

Dairy workers experience a high degree of bioaerosol exposure, composed of an array of biological and chemical constituents, which have been tied to adverse health effects. A better understanding of the variation in the magnitude and composition of exposures by task is needed to inform worker protection strategies. To characterize the levels and types of exposures, 115 dairy workers grouped into three task categories on nine farms in the high plains Western United States underwent personal monitoring for inhalable dust, endotoxin, 3-hydroxy fatty acids (3-OHFA), muramic acid, ergosterol, and ammonia through one work shift. Eighty-nine percent of dairy workers were exposed to endotoxin at concentrations exceeding the recommended exposure guidelines (adjusted for a long work shift). The proportion of workers with exposures exceeding recommended guidelines was lower for inhalable dust (12%), and ammonia (1%). Ergosterol exposures were only measurable on 28% of samples, primarily among medical workers and feed handlers. Milking parlor workers were exposed to significantly higher inhalable dust, endotoxin, 3-OHFA, ammonia, and muramic acid concentrations compared to workers performing other tasks. Development of large modern dairies has successfully made progress in reducing worker exposures and lung disease prevalence. However, exposure to endotoxin, dust, and ammonia continues to present a significant risk to worker health on North American dairies, especially for workers in milking parlors. This study was among the first to concurrently evaluate occupational exposure to assayable endotoxin (lipid A), 3-hydroxy fatty acids or 3-OHFA (a chemical measure of cell bound and noncell-bound endotoxins), muramic acid, ergosterol, and ammonia among workers on Western U.S. dairies. There remains a need for cost-effective, culturally acceptable intervention strategies integrated in OHS Risk Management and production systems to further optimize worker health and farm productivity.

Detection of low level benzene exposure in supermarket wrappers by urinary muconic acid.

PubMed

E S Johnson S Halabi G Netto G Lucier W Bechtold R Henderson

1999-01-01

Women who use the 'hot wire' and 'cool rod' machines to wrap meat in supermarkets are potentially exposed to low levels of benzene and polycyclic aromatic hydrocarbons present in fumes emitted during the thermal decomposition of the plastic used to wrap meat. In order to evaluate whether the benzene metabolite trans, trans-muconic acid (MA) can be used to monitor these low levels, we collected urine samples from supermarket workers, and assayed the urine for MA. Geometric mean after-shift MA levels were highest for subjects who used the 'hot wire' machine, i.e. > 300 ng mg-1 creatinine (Cr). The corresponding levels for subjects who used the 'cool rod' machine were similar to those for subjects who did not use either type of machine, and were much lower. These results indicate that urinary muconic acid has some potential for use in monitoring benzene exposures of less than 1 part per million (ppm). The study detected very high background MA levels (exceeding 2000 ng mg-1 Cr) in some subjects, suggesting that individuals in the general population without occupational exposure to benzene may have urinary MA levels equivalent to exposure to up to 2 ppm benzene in ambient air. However, since non-benzene sources of the metabolite cannot be completely ruled out as partially responsible for these high levels, the public health significance of this finding is not known at the moment.

Leaf surface and histological perturbations of leaves of Phaseolus vulgaris and Helianthus annuus after exposure to simulated acid rain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Evans, L.S.; Gmur, N.F.; Da Costa, F.

1977-08-01

Initial injury to adaxial leaf surfaces of Phaseolus vulgaris and Helianthus annuus occurred near trichomes and stomata after exposure to simulated sulfate acid rain. Lesion frequency was not correlated with density of either stomata or trichomes but was correlated with degree of leaf expansion. The number of lesions per unit area increased with total leaf area. Results suggest that characteristics of the leaf indumentum such as development of trichomes and guard cells and/or cuticle thickness near these structures may be involved in lesion development. Adaxial epidermal cell collapse was the first event in lesion development. Palisade cells and eventually spongymore » mesophyll cells collapsed after continued, daily exposure to simulated rain of low pH. Lesion development on Phaseolus vulgaris followed a specific course of events after exposure to simulated rain of known composition, application rate, drop size frequency, drop velocities, and frequency of exposures. These results allow development of further experiments to observe accurately other parameters, such as nutrient inputs and nutrient leaching from foliage, after exposure to simulated sulfate acid rain.« less

Lagged kernel machine regression for identifying time windows of susceptibility to exposures of complex mixtures.

PubMed

Liu, Shelley H; Bobb, Jennifer F; Lee, Kyu Ha; Gennings, Chris; Claus Henn, Birgit; Bellinger, David; Austin, Christine; Schnaas, Lourdes; Tellez-Rojo, Martha M; Hu, Howard; Wright, Robert O; Arora, Manish; Coull, Brent A

2018-07-01

The impact of neurotoxic chemical mixtures on children's health is a critical public health concern. It is well known that during early life, toxic exposures may impact cognitive function during critical time intervals of increased vulnerability, known as windows of susceptibility. Knowledge on time windows of susceptibility can help inform treatment and prevention strategies, as chemical mixtures may affect a developmental process that is operating at a specific life phase. There are several statistical challenges in estimating the health effects of time-varying exposures to multi-pollutant mixtures, such as: multi-collinearity among the exposures both within time points and across time points, and complex exposure-response relationships. To address these concerns, we develop a flexible statistical method, called lagged kernel machine regression (LKMR). LKMR identifies critical exposure windows of chemical mixtures, and accounts for complex non-linear and non-additive effects of the mixture at any given exposure window. Specifically, LKMR estimates how the effects of a mixture of exposures change with the exposure time window using a Bayesian formulation of a grouped, fused lasso penalty within a kernel machine regression (KMR) framework. A simulation study demonstrates the performance of LKMR under realistic exposure-response scenarios, and demonstrates large gains over approaches that consider each time window separately, particularly when serial correlation among the time-varying exposures is high. Furthermore, LKMR demonstrates gains over another approach that inputs all time-specific chemical concentrations together into a single KMR. We apply LKMR to estimate associations between neurodevelopment and metal mixtures in Early Life Exposures in Mexico and Neurotoxicology, a prospective cohort study of child health in Mexico City.

Health effects of acid aerosols on North American children: air pollution exposures.

PubMed Central

Spengler, J D; Koutrakis, P; Dockery, D W; Raizenne, M; Speizer, F E

1996-01-01

Air pollution measurements were conducted over a 1-year period in 24 North American communities participating in a respiratory health study. Ozone, particle strong acidity, sulfate, and mass (PM10 and PM2.1) were measured in all communities. In 20 of the communities, sulfur dioxide, ammonia, nitric acid, nitrous acid, and particulate nitrate were measured. The sampler was located centrally in the community whenever possible and samples were collected every other day. Concentrations of particle strong acidity, mass, sulfate, and ozone were highly correlated both in the region of the country defined as a high-sulfur source area and in the downwind transport regions. These regions of the eastern United States and southern Canada experienced the greatest particle strong acidity, sulfate, and particle mass concentrations during the spring and summer months (May-September). The particle strong acidity concentrations were highest in regions close to the high sulfur emission areas of the United States; that is, in the area immediately to the west of the Appalachian Plateau and west of the Allegheny Mountains (western Pennsylvania, eastern Ohio, and West Virginia) up through southern Ontario. The frequency of particle strong acidity events decreased with transport distance from the region of highest sulfur emissions. Low particle strong acidity and sulfates were found at the western and midwestern sites of both the United States and Canada. Substantial concentrations of nitric acid were found in two of the California sites as well as many sites in the northeastern portion of the United States. Sites selected for the epidemiologic study provide a range of annual mean particle strong acidity exposures from below the limit of detection to more than 50 nmol/m3. Images p492-a Figure 1. Figure 2. Figure 3. Figure 4. Figure 4. Figure 4. PMID:8743436

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…

Waist to hip ratio is a better predictor of esophageal acid exposure than body mass index.

PubMed

Ringhofer, C; Lenglinger, J; Riegler, M; Kristo, I; Kainz, A; Schoppmann, S F

2017-07-01

Obesity and gastroesophageal reflux disease (GERD) are major health problems showing an inconstant relationship in the literature. Therefore, anthropometric parameters which are predictive and can simply be assessed at first patient presentation may lead to a better patient selection for ambulatory reflux monitoring. We aimed to examine the association of body mass index (BMI) and waist to hip ratio (WHR) with gastroesophageal reflux activity during 24 hour-pH-impedance monitoring. Seven hundred and seventy-one patients with GERD symptoms underwent 24 hour-pH-impedance monitoring and high resolution manometry off proton pump inhibitors. Patients with known primary motility disorders of the esophagus and pre-existing endoscopic or operative procedure on esophagus or stomach were excluded from the study. Reflux parameters and anthropometric and demographic data from our prospectively gathered database were analyzed. We performed univariate and multivariate regression analysis to evaluate the associations of BMI and WHR with reflux parameters measured with 24 hour-pH-impedance monitoring. WHR showed a significantly stronger association with esophageal acid exposure than BMI (P<.001). Our data show that 6.9% of the percentage of endoluminal pH<4 in the distal esophagus is attributable to WHR. Furthermore, an association of WHR with impaired esophageal acid clearance was observed. Additionally, we observed an inverse relationship between lower esophageal sphincter integrity (P=.05) and esophageal acid exposure. WHR is a better predictor for esophageal acid exposure than BMI. Biomechanical and metabolic mechanisms of central fat distribution may influence reflux parameters in 24 hour pH impedance monitoring, which may affect patient selection for ambulatory reflux monitoring. © 2017 John Wiley & Sons Ltd.

Exposure-effect relationship of mycophenolic acid and prednisolone in adult patients with lupus nephritis.

PubMed

Abd Rahman, Azrin N; Tett, Susan E; Abdul Gafor, Halim A; McWhinney, Brett C; Staatz, Christine E

2015-11-01

The aim was to examine relationships between total and unbound mycophenolic acid (MPA) and prednisolone exposure and clinical outcomes in patients with lupus nephritis. Six blood samples were drawn pre- and at 1, 2, 4, 6 and 8 h post-dose and total and unbound MPA and prednisolone pre-dose (C0 ), maximum concentration (Cmax ) and area under the concentration-time curve (AUC) were determined using non-compartmental analysis in 25 patients. The analyses evaluated drug exposures in relation to treatment response since starting MPA and drug-related adverse events. Dose-normalized AUC varied 10-, 8-, 7- and 19-fold for total MPA, unbound MPA, total prednisolone and unbound prednisolone, respectively. Median values (95% CI) of total MPA AUC(0,8 h) (21.5 [15.0, 42.0] vs. 11.2 [4.8, 30.0] mg l(-1) h, P= 0.048) and Cmax (11.9 [6.7, 26.3] vs. 6.1 [1.6, 9.2] mg l(-1) , P = 0.016) were significantly higher in responders than non-responders. Anaemia was significantly associated with higher total (37.8 [14.1, 77.5] vs. 18.5 [11.7, 32.7] mg l(-1) h, P = 0.038) and unbound MPA AUC(0,12 h) (751 [214, 830] vs. 227 [151, 389] mg l(-1) h, P = 0.004). Unbound prednisolone AUC(0,24 h) was significantly higher in patients with Cushingoid appearance (unbound: 1372 [1242, 1774] vs. 846 [528, 1049] nmol l(-1) h, P = 0.019) than in those without. Poorer treatment response was observed in patients with lowest tertile exposure to both total MPA and prednisolone as compared with patients with middle and higher tertile exposure (17% vs. 74%, P = 0.023). This study suggests a potential role for therapeutic drug monitoring in individualizing immunosuppressant therapy in patients with lupus nephritis. © 2015 The British Pharmacological Society.

Delivery of extraterrestrial amino acids to the primitive Earth. Exposure experiments in Earth orbit.

PubMed

Barbier, B; Bertrand, M; Boillot, F; Chabin, A; Chaput, D; Henin, O; Brack, A

1998-06-01

A large collection of micrometeorites has been recently extracted from Antarctic old blue ice. In the 50 to 100 micrometers size range, the carbonaceous micrometeorites represent 80% of the samples and contain 2% of carbon. They might have brought more carbon to the surface of the primitive Earth than that involved in the present surficial biomass. Amino acids such as "-amino isobutyric acid have been identified in these Antarctic micrometeorites. Enantiomeric excesses of L-amino acids have been detected in the Murchison meteorite. A large fraction of homochiral amino acids might have been delivered to the primitive Earth via meteorites and micrometeorites. Space technology in Earth orbit offers a unique opportunity to study the behaviour of amino acids required for the development of primitive life when they are exposed to space conditions, either free or associated with tiny mineral grains mimicking the micrometeorites. Our objectives are to demonstrate that porous mineral material protects amino acids in space from photolysis and racemization (the conversion of L-amino acids into a mixture of L- and D-molecules) and to test whether photosensitive amino acids derivatives can polymerize in mineral grains under space conditions. The results obtained in BIOPAN-1 and BIOPAN-2 exposure experiments on board unmanned satellite FOTON are presented.

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.

Assessing human exposure to phthalic acid and phthalate esters from mineral water stored in polyethylene terephthalate and glass bottles.

PubMed

Montuori, P; Jover, E; Morgantini, M; Bayona, J M; Triassi, M

2008-04-01

Phthalic acid and phthalate esters are of growing interest due to their significant usage and potential toxicity. Polyethylene terephthalate (PET) and glass are both widely used materials for bottled drinking water. In this study, phthalic acid (PhA), bis(2-ethylhexyl) phthalate (DEHP), dimethyl phthalate (DMP), diethyl phthalate (DEP), diisobutyl phthalate (DiisoBP) and dibutyl phthalate (DBP) were analysed in a large number of Italian bottled water samples. These samples showed different concentrations of phthalates are nearly 20 times higher in samples bottled in PET than those from glass bottles with total levels of phthalates of 3.52 and 0.19 microg l(-1), respectively. However, the observed levels do not represent a significant exposure pathway when considering the US Environmental Protection Agency (USEPA) reference dose (an estimate of a daily oral exposure to the human population, including sensitive subgroups, that is likely to be without an appreciable risk of deleterious effects during a lifetime). In addition, no significant correlation was found between the phthalate concentrations and the physicochemical properties of the different water samples, apart from the still/sparkling water parameter for the PET samples. In this instance, slightly higher concentrations were observed for the PET bottled still water samples than for the sparkling water samples, although no explanation has been found yet.

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. Copyright © 2010 Elsevier B.V. All rights reserved.

A Longitudinal Analysis of Prenatal Exposure to Methylmercury and Fatty Acids in the Seychelles

PubMed Central

Stokes-Riner, Abbie; Thurston, Sally W.; J.Myers, Gary; Duffy, Emeir M.; Wallace, Julie; Bonham, Maxine; Robson, Paula; Shamlaye, Conrad F.; Strain, J.J.; Watson, Gene

2011-01-01

Background Maternal fish consumption during pregnancy exposes the fetus simultaneously to methyl mercury (MeHg) and long chain polyunsaturated fatty acids (LCPUFA). Data from the Seychelles Child Development Nutrition Study (SCDNS) showed a negative association of MeHg with child development when children were 30 months of age, only when controlling for LCPUFA. Concomitantly, n-3 LCPUFA were found to have a significant positive association only at 9 months. These findings suggest that the effects of MeHg and LCPUFA may vary with age over the first few years of life. We address this by including outcomes at two ages and adjusting for the child's age at testing. Methods A longitudinal analysis utilizing linear mixed models was performed to assess the associations of maternal hair total mercury (THg, a biomarker for MeHg) and maternal LCPUFA with children's Bayley Scales of Infant Development Psychomotor Developmental Index (BSID-II PDI) at 9 and 30 months of age, and to determine whether these associations change over time. Data from 228 children were included. Results Maternal hair MeHg had a negative effect on BSID PDI, while maternal n-3 LCPUFA had a positive effect. These effects did not change significantly from 9 to 30 months in this analysis. Conclusions The longitudinal analysis provides increased power for estimating the relationships of prenatal MeHg and LCPUFA exposures during child development. Significant associations of these exposures in opposite directions confirm the importance of LCPUFA in development and the need to adjust for maternal nutrition when studying prenatal MeHg exposure. PMID:21145963

A longitudinal analysis of prenatal exposure to methylmercury and fatty acids in the Seychelles.

PubMed

Stokes-Riner, Abbie; Thurston, Sally W; Myers, Gary J; Duffy, Emeir M; Wallace, Julie; Bonham, Maxine; Robson, Paula; Shamlaye, Conrad F; Strain, J J; Watson, Gene; Davidson, Philip W

2011-01-01

Maternal fish consumption during pregnancy exposes the fetus simultaneously to methylmercury (MeHg) and long chain polyunsaturated fatty acids (LCPUFA). Data from the Seychelles Child Development Nutrition Study (SCDNS) showed a negative association of MeHg with child development when children were 30 months of age, only when controlling for LCPUFA. Concomitantly, n-3 LCPUFA were found to have a significant positive association only at 9 months. These findings suggest that the effects of MeHg and LCPUFA may vary with age over the first few years of life. We address this by including outcomes at two ages and adjusting for the child's age at testing. A longitudinal analysis utilizing linear mixed models was performed to assess the associations of maternal hair total mercury (THg, a biomarker for MeHg) and maternal LCPUFA with children's Bayley Scales of Infant Development Psychomotor Developmental Index (BSID-II PDI) at 9 and 30 months of age, and to determine whether these associations change over time. Data from 228 children were included. Maternal hair MeHg had a negative effect on BSID PDI, while maternal n-3 LCPUFA had a positive effect. These effects did not change significantly from 9 to 30 months in this analysis. The longitudinal analysis provides increased power for estimating the relationships of prenatal MeHg and LCPUFA exposures during child development. Significant associations of these exposures in opposite directions confirm the importance of LCPUFA in development and the need to adjust for maternal nutrition when studying prenatal MeHg exposure. Copyright © 2010 Elsevier B.V. All rights reserved.

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.

Optimization of Exposure Time Division for Multi-object Photometry

NASA Astrophysics Data System (ADS)

Popowicz, Adam; Kurek, Aleksander R.

2017-09-01

Optical observations of wide fields of view entail the problem of selecting the best exposure time. As many objects are usually observed simultaneously, the quality of photometry of the brightest ones is always better than that of the dimmer ones, even though all of them are frequently equally interesting for astronomers. Thus, measuring all objects with the highest possible precision is desirable. In this paper, we present a new optimization algorithm, dedicated for the division of exposure time into sub-exposures, which enables photometry with a more balanced noise budget. The proposed technique increases the photometric precision of dimmer objects at the expense of the measurement fidelity of the brightest ones. We have tested the method on real observations using two telescope setups, demonstrating its usefulness and good consistency with theoretical expectations. The main application of our approach is a wide range of sky surveys, including ones performed by space telescopes. The method can be used to plan virtually any photometric observation of objects that show a wide range of magnitudes.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mohamed, A.A.E.K.; Hamed, A.A.S.; Elhaimi, Y.A.A.

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<.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 weremore » 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.« less

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.

Odors: appetizing or satiating? Development of appetite during odor exposure over time.

PubMed

Ramaekers, M G; Boesveldt, S; Lakemond, C M M; van Boekel, M A J S; Luning, P A

2014-05-01

Exposure to palatable food odors influences appetite responses, either promoting or inhibiting food intake. Possibly, food odors are appetizing after a short exposure (of circa 1-3 min), but become satiating over time (circa 10-20 min). To investigate the effect of odor exposure on general appetite and sensory-specific appetite (SSA) over time. In a cross-over study, 21 unrestrained women (age: 18-45 years; BMI: 18.5-25 kg m(-2)) were exposed for 20 min to eight different odor types: five food odors, two nonfood odors and no-odor. All odors were distributed in a test room at suprathreshold levels. General appetite, SSA and salivation were measured over time. All food odors significantly increased general appetite and SSA, compared with the no-odor condition. The nonfood odors decreased general appetite. All effects did not change over time during odor exposure. Savory odors increased the appetite for savory foods, but decreased appetite for sweet foods, and vice versa after exposure to sweet odors. Neither food odors nor nonfood odors affected salivation. Palatable food odors were appetizing during and after odor exposure and did not become satiating over a 20-min period. Food odors had a large impact on SSA and a small impact on general appetite. Moreover, exposure to food odors increased the appetite for congruent foods, but decreased the appetite for incongruent foods. It may be hypothesized that, once the body is prepared for intake of a certain food with a particular macronutrient composition, it is unfavorable to consume foods that are very different from the cued food.

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

Effect of intermittent exposure to 3% CO2 on respiration, acid-base balance, and calcium-phosphorus metabolism.

PubMed

Schaefer, K E; Carey, C R; Dougherty, J H; Morgan, C; Messier, A A

1979-01-01

One subject was exposed for six days to increasing levels of CO2, rising at a constant rate from 0.03 to 3.0% CO2 within a 15-h period followed by 9 h of air breathing. To assess acid-base parameters, arterialized capillary blood was taken from a finger twice daily (at 8 a.m. and 11 p.m.) at times corresponding to the beginning and end of the intermittent exposure to CO2. Venous blood samples were obtained on alternate days at the same times. Urine specimens were collected twice daily. The subject was on a liquid diet. Resting respiratory minute volume (VE), oxygen consumption (VO2), carbon dioxide excretion (VCO2), alveolar carbon dioxide and oxygen tension (PACO2) and PAO2) were measured twice daily. PACO2 and PAO2 were also determined at the end of breath-holding twice daily; CO2 tolerance tests and lung function tests were also carried out. In contrast to the effects of chronic exposure to 3% CO2, the CO2 tolerance tests showed an increased sensitivity (increase of slope) and breath-holding PACO2 did not change, indicating that acclimatization to CO2 did not develop. The ventilatory response to CO2 was not sufficient to prevent CO2 accumulation in the body; this accumulation was eliminated during the nightly air-breathing periods on the fourth and fifth days, indicated by higher values of PaCO2 and PACO2. The known renal response to hypercapnia, consisting of an increased excretion of titratable acidity, ammonia, and hydrogen ion excretion, occurred but was interrupted after the first day and was triggered again on the fourth and fith days when accumulated CO2 was released from body CO2 stores. The second renal response was associated with a marked calcium excretion, which suggests that bone CO2 stores were involved.

[Solar exposure time for sunburn in Mexican population].

PubMed

Castanedo Cázares, Juan Pablo; Torres Álvarez, Bertha; Sobrevilla Ondarza, Salvador; Ehnis Pérez, Adriana; Gordillo Moscoso, Antonio

2012-01-01

THe minimal erythemal dose (MED) quantifies an individual's sensitivity to UV radiation (UVR). To estimate it in our population and establish the time of exposure inducing it during daily activities would allow us to calculate risk intervals. From 2005-2012, the UV solar radiation was measured with terrestrial radiometry and compared to public UV index (UVI). We determined the MED in 90 individuals with the prevalent phototypes in Mexico (III, IV, V), and estimated the time needed for the development of sunburn. The average MED for phototype III was 39 (IC 95%: 35-42) mJ/cm2, for IV 48 (IC 95%:42-53) mJ/cm2, and for V was 84 (IC 95%:75-92) mJ/cm2 (ANOVA, p ≤ 0.001). Approximately, 80% of the daily UVR was accumulated between 10:00-16:00 h, and 77% of the annual UV dose is received between March-October. The public UVI had a high correlation with the one quantified at terrestrial level (r = 0.89; p ≤ 0.001). Mexico receives continuously high levels of UVR. Phototype III will present sunburn after 22-33 min in a summer day, while phototype V will require over one hour of exposure. This last group is at risk of chronic exposure without considering consequences.

Effects of post exposure bake temperature and exposure time on SU-8 nanopattern obtained by electron beam lithography

NASA Astrophysics Data System (ADS)

Yasui, Manabu; Kazawa, Elito; Kaneko, Satoru; Takahashi, Ryo; Kurouchi, Masahito; Ozawa, Takeshi; Arai, Masahiro

2014-11-01

SU-8 is a photoresist imaged using UV rays. However, we investigated the characteristics of an SU-8 nanopattern obtained by electron beam lithography (EBL). In particular, we studied the relationship between post-exposure bake (PEB) temperature and exposure time on an SU-8 nanopattern with a focus on phase transition temperature. SU-8 residue was formed by increasing both PEB temperature and exposure time. To prevent the formation of this, Monte Carlo simulation was performed; the results of such simulation showed that decreasing the thickness of SU-8 can reduce the amount of residue from the SU-8 nanopattern. We confirmed that decreasing the thickness of SU-8 can also prevent the formation of residue from the SU-8 nanopattern with EBL.

Biomonitoring of 2,4-Dichlorophenoxyacetic Acid Exposure and Dose in Farm Families

PubMed Central

Alexander, Bruce H.; Mandel, Jack S.; Baker, Beth A.; Burns, Carol J.; Bartels, Michael J.; Acquavella, John F.; Gustin, Christophe

2007-01-01

Objective We estimated 2,4-dichlorophenoxyacetic acid (2,4-D) exposure and systemic dose in farm family members following an application of 2,4-D on their farm. Methods Farm families were recruited from licensed applicators in Minnesota and South Carolina. Eligible family members collected all urine during five 24-hr intervals, 1 day before through 3 days after an application of 2,4-D. Exposure profiles were characterized with 24-hr urine 2,4-D concentrations, which then were related to potential predictors of exposure. Systemic dose was estimated using the urine collections from the application day through the third day after application. Results Median urine 2,4-D concentrations at baseline and day after application were 2.1 and 73.1 μ g/L for applicators, below the limit of detection, and 1.2 μ g/L for spouses, and 1.5 and 2.9 μ g/L for children. The younger children (4–11 years of age) had higher median post-application concentrations than the older children (≥ 12 years of age) (6.5 vs. 1.9 μ g/L). The geometric mean systemic doses (micrograms per kilogram body weight) were 2.46 (applicators), 0.8 (spouses), 0.22 (all children), 0.32 (children 4–11 years of age), and 0.12 (children ≥ 12 years of age). Exposure to the spouses and children was primarily determined by direct contact with the application process and the number of acres treated. Multivariate models identified glove use, repairing equipment, and number of acres treated as predictors of exposure in the applicators. Conclusions We observed considerable heterogeneity of 2,4-D exposure among farm family members, primarily attributable to level of contact with the application process. Awareness of this variability and the actual magnitude of exposures are important for developing exposure and risk characterizations in 2,4-D–exposed agricultural populations. PMID:17431485

Contribution to volatile organic compound exposures from time spent in stores and restaurants and bars.

PubMed

Loh, Miranda M; Houseman, E Andres; Levy, Jonathan I; Spengler, John D; Bennett, Deborah H

2009-11-01

Many people spend time in stores and restaurants, yet there has been little investigation of the influence of these microenvironments on personal exposure. Relative to the outdoors, transportation, and the home, these microenvironments have high concentrations of several volatile organic compounds (VOCs). We developed a stochastic model to examine the effect of VOC concentrations in these microenvironments on total personal exposure for (1) non-smoking adults working in offices who spend time in stores and restaurants or bars and (2) non-smoking adults who work in these establishments. We also compared the effect of working in a smoking versus non-smoking restaurant or bar. Input concentrations for each microenvironment were developed from the literature whereas time activity inputs were taken from the National Human Activity Patterns Survey. Time-averaged exposures were simulated for 5000 individuals over a weeklong period for each analysis. Mean contributions to personal exposure from non-working time spent in stores and restaurants or bars range from <5% to 20%, depending on the VOC and time-activity patterns. At the 95th percentile of the distribution of the proportion of personal exposure attributable to time spent in stores and restaurants or bars, these microenvironments can be responsible for over half of a person's total exposure to certain VOCs. People working in restaurants or bars where smoking is allowed had the highest fraction of exposure attributable to their workplace. At the median, people who worked in stores or restaurants tended to have 20-60% of their total exposures from time spent at work. These results indicate that stores and restaurants can be large contributors to personal exposure to VOCs for both workers in those establishments and for a subset of people who visit these places, and that incorporation of these non-residential microenvironments can improve models of personal exposure distributions.

Estimating human exposure to PFOS isomers and PFCA homologues: the relative importance of direct and indirect (precursor) exposure.

PubMed

Gebbink, Wouter A; Berger, Urs; Cousins, Ian T

2015-01-01

Contributions of direct and indirect (via precursors) pathways of human exposure to perfluorooctane sulfonic acid (PFOS) isomers and perfluoroalkyl carboxylic acids (PFCAs) are estimated using a Scenario-Based Risk Assessment (SceBRA) modelling approach. Monitoring data published since 2008 (including samples from 2007) are used. The estimated daily exposures (resulting from both direct and precursor intake) for the general adult population are highest for PFOS and perfluorooctanoic acid (PFOA), followed by perfluorohexanoic acid (PFHxA) and perfluorodecanoic acid (PFDA), while lower daily exposures are estimated for perfluorobutanoic acid (PFBA) and perfluorododecanoic acid (PFDoDA). The precursor contributions to the individual perfluoroalkyl acid (PFAA) daily exposures are estimated to be 11-33% for PFOS, 0.1-2.5% for PFBA, 3.7-34% for PFHxA, 13-64% for PFOA, 5.2-66% for PFDA, and 0.7-25% for PFDoDA (ranges represent estimated precursor contributions in a low- and high-exposure scenario). For PFOS, direct intake via diet is the major exposure pathway regardless of exposure scenario. For PFCAs, the dominant exposure pathway is dependent on perfluoroalkyl chain length and exposure scenario. Modelled PFOS and PFOA concentrations in human serum using the estimated intakes from an intermediate-exposure scenario are in agreement with measured concentrations in different populations. The isomer pattern of PFOS resulting from total intakes (direct and via precursors) is estimated to be enriched with linear PFOS (84%) relative to technical PFOS (70% linear). This finding appears to be contradictory to the observed enrichment of branched PFOS isomers in recent human serum monitoring studies and suggests that either external exposure is not fully understood (e.g. there are unknown precursors, missing or poorly quantified exposure pathways) and/or that there is an incomplete understanding of the isomer-specific human pharmacokinetic processes of PFOS, its precursors and

Assessment of the vaginal residence time of biomarkers of semen exposure.

PubMed

Thurman, Andrea; Jacot, Terry; Melendez, Johan; Kimble, Thomas; Snead, Margaret; Jamshidi, Roxanne; Wheeless, Angie; Archer, David F; Doncel, Gustavo F; Mauck, Christine

2016-11-01

The primary objective of this pilot study is to determine and compare the residence time in the vagina of biomarkers of semen exposure for up to 15 days post exposure. The biomarkers are prostate-specific antigen (PSA), Y chromosome DNA, the sex determining region of the Y chromosome (SRY) and testis-specific protein Y-encoded 4 (TSPY4). The secondary objectives are to determine if biomarker concentrations differed between intercourse and inoculation groups, to establish whether the sampling frequency post exposure affected biomarker concentrations and decay profile and to determine if biomarker concentrations in vaginal swabs obtained by the participant at home were similar to swabs obtained by the nurse in the clinic. We randomized healthy women to unprotected intercourse (n=17) versus vaginal inoculation with the male partner's semen in the clinic (n=16). Women were then further randomized to have vaginal swabs obtained at either 7 or 4 time points after semen exposure, up to 15 days post exposure, either obtained at home by the participant or in the clinic by the research nurse. PSA and SRY were markers of recent semen exposure. TSPY4 was detectable in approximately 50% of participants at 15 days post exposure. Unprotected intercourse resulted in significantly higher concentrations of select biomarkers. Sampling frequency and home versus clinic sampling had no significant effect on biomarker concentrations. Objective biomarkers of recent or distant semen exposure may have great utility for verifying protocol compliance in a variety of clinical trials. Copyright © 2016 Elsevier Inc. All rights reserved.

Correlation between urinary methoxyacetic acid and exposure of ethylene glycol dimethyl ether in a lithium battery plant.

PubMed

Yokota, Kozo; Ueno, Hiroshi; Ikeda, Naoko; Johyama, Yasushi; Michitsuji, Hiromi; Yamada, Seiji

2007-10-01

To examine the correlation between airborne ethylene glycol dimethyl ether (EGdiME) exposures and the urinary methoxyacetic acid (MAA) and to approach the issue of a permissible exposure limit for EGdiME. The survey was conducted on Thursday. Workers occupationally exposed to EGdiME, as well as nonexposed controls, were studied in combination with one of the authors, who was coincidentally exposed to EGdiME while carrying out the study. Air levels of EGdiME were determined by personal sampling on passive gas tubes. Urine was collected from nine control subjects and ten workers immediately before and after the shift, and from one of the authors at intervals during 12 h. The analyses of EGdiME in air and MAA in urine were performed by gas chromatography with flame ionization detection. The time-weighted average (TWA) air levels of EGdiME ranged from 0.7 to 10.5 ppm during 8 h work shifts. The urinary levels of MAA in one of the authors increased continuously during exposure and after the end of exposure. The levels of urinary MAA in the exposed workers were significantly higher than those in the control subjects. On the other hand, the postshift values were higher than the preshift values in the exposed workers, but the difference was not significant. A linear correlation was found between the TWA air levels of EGdiME and creatinine-adjusted MAA levels in urine collected at the end of the shift (r = 0.933; P < 0.0001). According to our equation, a linear extrapolation to the biological limit value recommended by Shih et al. (1999) of 40 mg MAA/g crea indicated an average inhalation exposure to EGdiME over the workweek of 12 ppm. These results indicate that the determination of MAA in urine is suitable for use in the biological monitoring of EGdiME exposure.

Models for mesothelioma incidence following exposure to fibers in terms of timing and duration of exposure and the biopersistence of the fibers.

PubMed

Berry, G

1999-02-01

The health effects of inhaled fibers are related to the intensity and duration of exposure and occur many years after the exposure. In particular, the incidence of mesothelioma after exposure to asbestos is proportional to the intensity of exposure (fibers per milliliter of air) and the duration of exposure, and to the time that has elapsed since the exposure. The incidence increases with time since exposure to a power of between 3 and 4. The disease process resulting from exposure to fibers in the air is presumably related to the dose of fibers in the lungs, which depends on the exposure level and duration, and also on the size characteristics of the fibers influencing their inhalation and retention in the lungs. Models incorporating these characteristics have been found to be satisfactory in explaining the incidence of mesothelioma over time after exposure to asbestos. Most of the epidemiological modeling has been for occupational exposure to one of the amphibole asbestos types (crocidolite or amosite), for which heavy exposure produces a high incidence of mesothelioma. Occupational exposure to chrysotile asbestos has resulted in a much lower incidence of mesothelioma. Crocidolite asbestos is much more biopersistent than chrysotile asbestos in the sense that after retention in the lungs it is eliminated only slowly (half-time of several years). If fibers are eliminated then the dose in the lungs declines following exposure, and this may influence the disease process. This concept is more important for synthetic mineral fibers, such as glass wool, which are used as a substitute for asbestos. These fibers are much less biopersistent than asbestos, with half-times of weeks or even days. Biopersistence is related to the dissolution of fibers. This is a physical-chemical process that may be expected to proceed at about the same rate in rats and humans. The predicted effect of biopersistence of fibers has been explored using the basic mesothelioma incidence model

Gestational exposure to perfluorooctanoic acid (PFOA): alterations in motor related behaviors

PubMed Central

Goulding, David R.; White, Sally S.; McBride, Sandra J.; Fenton, Suzanne E.; Harry, G. Jean

2016-01-01

Perfluoroalkyl and polyfluoroalkyl substances are used in commercial applications and developmental exposure has been implicated in alterations in neurobehavioral functioning. While associations between developmental perfluorooctanoic acid (PFOA) exposure and human outcomes have been inconsistent, studies in experimental animals suggest alterations in motor related behaviors. To examine a dose-response pattern of neurobehavioral effects following gestational exposure to PFOA, pregnant CD-1 mice received PFOA (0, 0.1, 0.3, 1.0 mg/kg/day) via oral gavage from gestational day 1–17 and the male offspring examined. Motor activity assessments on postnatal day (PND)18, 19, and 20 indicated a shift in the developmental pattern with an elevated activity level observed in the 1.0 mg/kg/day dose group on PND18. In the adult, no alterations were observed in body weights, activity levels, diurnal pattern of running wheel activity, startle response, or pre-pulse startle inhibition. In response to a subcutaneous injection of saline or nicotine (80 µg/kg), all animals displayed a transient increase in activity likely associated with handling with no differences observed across dose groups. Inhibition of motor activity over 18 days of 400µg/kg nicotine injection was not significantly different across dose groups. Hyperactivity induced by 2mg/kg (+)-methamphetamine hydrochloride intraperitoneal injection was significantly lower in the 1.0 mg/kg/day PFOA dose group as compared to controls. Taken together, these data suggest that the effects on motor-related behaviors with gestational PFOA exposure do not mimic those reported for acute postnatal exposure. Changes were not observed at dose level under 1.0 mg/kg/day PFOA. Further examination of pathways associated with methamphetamine-induced activity is warranted. PMID:27888120

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

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

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

PubMed

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

2016-08-01

Perfluorooctanoic acid (PFOA or C8) has hepatotoxic effects in animals. Cross-sectional epidemiologic studies suggest PFOA is associated with liver injury biomarkers. We estimated associations between modeled historical PFOA exposures and liver injury biomarkers and medically validated liver disease. 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). 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). 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 diagnosed liver disease. Darrow LA, Groth AC, Winquist A, Shin HM

75 FR 37738 - 1-Naphthaleneacetic Acid; Time-Limited Tolerance, Technical Correction

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-30

...-Naphthaleneacetic Acid; Time-Limited Tolerance, Technical Correction AGENCY: Environmental Protection Agency (EPA..., ethylene oxide, fenvalerate, et al.; tolerance actions. Today's rule restores the time-limited tolerance...-3) establishing a time-limited tolerance for residues of 1-naphthaleneacetic acid ethyl ester in or...

Color, dispersion, and exposure time in performance on rotated figure recognition.

PubMed

Huang, Kuo-Chen; Lee, Shin-Tsann; Chang, Chun-Chieh

2008-10-01

This study investigated the effects of dispersion, color, and rotation of figures on recognition under varied exposure times. A total of 30 women and 15 men, Taiwanese college students ages 18 to 20 years (M = 19.1, SD = 1.2), participated. Subjects were to recognize a target figure and respond with its location in each stimulus by pressing a mouse button. Analysis showed that the effect of rotation on accuracy was significant. Accuracy for the rotation of 180 degrees was greater than those for 60 degrees and 300 degrees. Exposure time also significantly influenced accuracy. The accuracy was greater for 2 and 3 sec. than for 1 sec. No significant effects on accuracy were associated with dispersion and color, and neither had any interactive effect on accuracy. Dispersion significantly affected the response time as response time for dispersion under 0.4 and 0.5 conditions were shorter than those under 0.2 and 0.3 conditions. Significantly less response time was needed for rotation of 180 degrees than for 60 degrees and 300 degrees conditions. Response time was longer for red figures than for blue, green, and yellow figures. No significant effect on response time was associated with duration of exposure. Two interactive two-way effects were found: dispersion x color of figure and dispersion x rotation. Implications for figure or icon design are discussed.

Time trends and demographic differences in youth exposure to alcohol advertising on television.

PubMed

Ringel, Jeanne S; Collins, Rebecca L; Ellickson, Phyllis L

2006-10-01

To examine trends in youth exposure to alcohol advertising on television across different demographic groups. We used television ratings data on alcohol advertisements to examine trends in exposure between September 1998 and February 2002. Further, we explored the differences in exposure across demographic groups by examining group-level alcohol ad exposure across specific networks, program types, and times of day. We found that boys were more exposed than girls and African-Americans are more exposed than whites. Moreover, the race differential appeared to be increasing over time, whereas the gender differential appeared to increase with age. Differences in viewing patterns across race and gender contributed to the observed differences in exposure to alcohol advertising on television. These results provide guidance in identifying comparative vulnerabilities in exposure to alcohol advertising on television, and can aid in the development of strategies to inoculate youth against those vulnerabilities.

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

Dysregulation of major functional genes in frontal cortex by maternal exposure to carbon black nanoparticle is not ameliorated by ascorbic acid pretreatment.

PubMed

Onoda, Atsuto; Takeda, Ken; Umezawa, Masakazu

2018-09-01

Recent cohort studies have revealed that perinatal exposure to particulate air pollution, including carbon-based nanoparticles, increases the risk of brain disorders. Although developmental neurotoxicity is currently a major issue in the toxicology of nanoparticles, critical information for understanding the mechanisms underlying the developmental neurotoxicity of airway exposure to carbon black nanoparticle (CB-NP) is still lacking. In order to investigate these mechanisms, we comprehensively analyzed fluctuations in the gene expression profile of the frontal cortex of offspring mice exposed maternally to CB-NP, using microarray analysis combined with Gene Ontology information. We also analyzed differences in the enriched function of genes dysregulated by maternal CB-NP exposure with and without ascorbic acid pretreatment to refine specific alterations in gene expression induced by CB-NP. Total of 652 and 775 genes were dysregulated by CB-NP in the frontal cortex of 6- and 12-week-old offspring mice, respectively. Among the genes dysregulated by CB-NP, those related to extracellular matrix structural constituent, cellular response to interferon-beta, muscle organ development, and cysteine-type endopeptidase inhibitor activity were ameliorated by ascorbic acid pretreatment. A large proportion of the dysregulated genes, categorized in hemostasis, growth factor, chemotaxis, cell proliferation, blood vessel, and dopaminergic neurotransmission, were, however, not ameliorated by ascorbic acid pretreatment. The lack of effects of ascorbic acid on the dysregulation of genes following maternal CB-NP exposure suggests that the contribution of oxidative stress to the effects of CB-NP on these biological functions, i.e., cell migration and proliferation, blood vessel maintenance, and dopaminergic neuron system, may be limited. At least, ascorbic acid pretreatment is hardly likely to be able to protect the brain of offspring from developmental neurotoxicity of CB-NP. The

In utero exposure to valproic acid changes sleep in juvenile rats: a model for sleep disturbances in autism.

PubMed

Cusmano, Danielle M; Mong, Jessica A

2014-09-01

To determine whether sleep disturbances are found in the valproic acid model of autism spectrum disorders (ASD). Comparative study for sleep behavior, sleep architecture, electroencephalogram (EEG) spectral analysis, and glutamic acid decarboxylase (GAD) 65/67 protein expression in juvenile rats exposed to valproic acid (VPA), sodium salt, or saline in utero. N/A. Juvenile (postnatal day 32) male and female Sprague-Dawley rats. In utero exposure to either saline or 400 mg/kg VPA administered intraperitoneally to the dams on gestational day 12.5. On postnatal days 22-24, all rats were implanted with transmitters to record EEG and electromyogram (EMG) activity. During the light phase, when nocturnal animals are typically quiescent, the VPA-exposed animals spent significantly more time in wake (∼35 min) and significantly less time in non-rapid eye movement (NREM) sleep (∼26 min) compared to the saline controls. Furthermore, spectral analysis of the EEG revelled that VPA-exposed animals exhibited increased high-frequency activity during wake and rapid eye movement (REM) sleep and reduced theta power across all vigilance states. Interestingly, the gamma-aminobutyric acid (GABA)-ergic system, which modulates the induction and maintenance of sleep states, was also disrupted, with reduced levels of both GAD 65 and GAD67 in the cortical tissue of VPA-exposed animals compared to saline controls. To date, the current animal models of ASD have been underutilized in the investigation of associated sleep disturbances. The VPA animal model recapitulates aspects of sleep disruptions reported clinically, providing a tool to investigate cellular and molecular dysregulation contributing to sleep disruptions in ASD. © 2014 Associated Professional Sleep Societies, LLC.

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.

Risk assessment of plant food supplements and other herbal products containing aristolochic acids using the margin of exposure (MOE) approach.

PubMed

Abdullah, Rozaini; Diaz, Leolean Nyle; Wesseling, Sebastiaan; Rietjens, Ivonne M C M

2017-02-01

After the incidences of induction of aristolochic acid nephropathy after consumption of herbal weight loss preparations that accidentally contained aristolochic acids (AAs), several countries defined national restrictions on the presence of AAs in food, including plant food supplements (PFS) and herbal products. This study investigates whether the risks associated with exposure to AAs via PFS and herbal products are at present indeed negligible. Data reported in literature on AA levels in PFS and other herbal products and also obtained from a new series of PFS in the present study were used to calculate the estimated daily intakes (EDIs) and corresponding margins of exposure (MOEs). Available literature data revealed that 206 out of 573 samples were found to contain aristolochic acid I (AAI) and/or aristolochic acid II (AAII). The results obtained from recently collected PFS revealed that both AAI and AAII were detected in three out of 18 analysed PFS at levels up to 594.8 and 235.3 µg g -1 , respectively, being in line with the levels reported in literature. The EDIs resulting from intake of these PFS resulted in MOEs that were generally below 10,000, corroborating the priority for risk management. Although these results refer to PFS collected by targeted sampling strategies, the data reveal that AA-containing PFS are still freely available. When considering that the use of these samples may be limited to shorter periods of time, the EDIs might be lower, but MOE values would still be lower than 10,000 for more than 50% of the AA-containing PFS and herbal products. In conclusion, the presence of AAs in PFS and herbal products even several years after instalment of the legal restrictions still raises concern, especially for people who frequently use the respective PFS and herbal products.

The timing of exposure in clinic-based treatment for childhood anxiety disorders.

PubMed

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

2013-03-01

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 drop-out rates were compared with those obtained through efficacy and effectiveness trials of manualized treatment for anxious youth. Findings from the authors' clinical data revealed significantly shorter treatment duration with exposures implemented sooner than in the previous studies. Dropout rates were significantly higher than in the efficacy trial but comparable with the effectiveness trial. Outcome data from a subset of eight patients revealed large effect sizes. These findings suggest that effective treatment can be shorter and more focused on exposure than is often outlined in manuals and have important implications for outcome research and dissemination.

Investigating the American Time Use Survey from an exposure modeling perspective.

PubMed

George, Barbara Jane; McCurdy, Thomas

2011-01-01

This paper describes an evaluation of the US 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 activities they undertake in those locations. The data are reported as a series of sequential activities over a 24-h time period--a "diary day"--starting at 0400 hours. Between 12,000 and 13,000 surveys are obtained each year and the Bureau has plans to continue ATUS for the foreseeable future. The ATUS already has about 73,000 diary days of data, more than twice as many as that which currently exists in the US Environmental Protection Agency's (EPA) "Consolidated Human Activity Database" (CHAD) that the Agency uses for exposure modeling purposes. There are limitations for using ATUS in modeling human exposures to environmental pollutants. The ATUS does not report the location for a number of activities regarded as "personal." For 2006, personal activities with missing location information totaled 572 min/day, on average, for survey participants: about 40% of their day. Another limitation is that ATUS does not distinguish between indoor and outdoor activities at home, two of the traditional locational demarcations used in human exposure modeling. This lack of information affects exposure estimates to both indoor and outdoor air pollutants and potentially affects non-dietary ingestion estimates for children, which can vary widely depending on whether or not a child is indoors. Finally, a detailed analysis of the work travel activity in a subsample from ATUS 2006 indicates that the coding scheme is not fully consistent with a CHAD-based exposure modeling approach. For ATUS respondents in this subsample who reported work as an activity, roughly 48% of their days were missing work travel at one or both ends of the work shift or reported within work-shift travel inconsistently. An extensive effort

Impact of desiccation and heat exposure stress on Salmonella tolerance to acidic conditions.

PubMed

Richardson, Kurt E; Cox, Nelson A; Cosby, Douglas E; Berrang, Mark E

2018-02-01

In a recent study, the pH of commonly used Salmonella pre-enrichment media became acidic (pH 4.0 to 5.0) when feed or feed ingredients were incubated for 24 h. Acidic conditions have been reported to injure or kill Salmonella. In this study, cultures of four known feed isolates (S. montevideo, S. senftenberg, S. tennessee, and S. schwarzengrund) and four important processing plant isolates (S. typhimurium, S. enteritidis, S. infantis, and S. heidelberg) were grown on meat and bone meal and later subjected to desiccation and heat exposure to stress the microorganism. The impact of stress on the isolates ability to survive in acidic conditions ranging from pH 4.0 to 7.0 was compared to the non-stressed isolate. Cell injury was determined on xylose lysine tergitol 4 (XLT4) and cell death determined on nutrient agar (NA). When measured by cell death in non-stressed Salmonella, S. typhimurium was the most acid tolerant and S. heidelberg was the most acid sensitive whereas in stressed Salmonella, S. senftenberg was the most acid tolerant and S. tennessee was the most acid sensitive. The pH required to cause cell injury varied among isolates. With some isolates, the pH required for 50% cell death and 50% cell injury was similar. In other isolates, cell injury occurred at a more neutral pH. These findings suggest that the pH of pre-enrichment media may influence the recovery and bias the serotype of Salmonella recovered from feed during pre-enrichment.

A biological indicator of inorganic arsenic exposure using the sum of urinary inorganic arsenic and monomethylarsonic acid concentrations

PubMed Central

Hata, Akihisa; Kurosawa, Hidetoshi; Endo, Yoko; Yamanaka, Kenzo; Fujitani, Noboru; Endo, Ginji

2016-01-01

Objectives: The sum of urinary inorganic arsenic (iAs), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) concentrations is used for the biological monitoring of occupational iAs exposure. Although DMA is a major metabolite of iAs, it is an inadequate index because high DMA levels are present in urine after seafood consumption. We estimated the urinary iAs+MMA concentration corresponding to iAs exposure. Methods: We used data from two arsenic speciation analyses of urine samples from 330 Bangladeshi with oral iAs exposure and 172 Japanese workers without occupational iAs exposure using high-performance liquid chromatography with inductively coupled plasma mass spectrometry. Results: iAs, MMA, and DMA, but not arsenobetaine (AsBe), were detected in the urine of the Bangladeshi subjects. The correlation between iAs+MMA+DMA and iAs+MMA was obtained as log (iAs+MMA) = 1.038 log (iAs+MMA+DMA) -0.658. Using the regression formula, the iAs+MMA value was calculated as 2.15 and 7.5 μg As/l, corresponding to 3 and 10 μg As/m3 of exposures, respectively. In the urine of the Japanese workers, arsenic was mostly excreted as AsBe. We used the 95th percentile of iAs+MMA (12.6 μg As/l) as the background value. The sum of the calculated and background values can be used as a biological indicator of iAs exposure. Conclusion: We propose 14.8 and 20.1 μg As/l of urinary iAs+MMA as the biological indicators of 3 and 10 μg As/m3 iAs exposure, respectively. PMID:27010090

Glutaraldehyde inhalation exposure of rats: effects on lung morphology, Clara-cell protein, and hyaluronic acid levels in BAL.

PubMed

Halatek, T; Opalska, B; Swiercz, R; Palczynski, C; Gorski, P; Rydzynski, K; Bernard, A

2003-01-01

Glutaraldehyde (GA) is a biocide widely used in hospital and laboratory practice. GA is a volatile substance and, under certain circumstances, significant airborne concentrations may be generated at room temperature. Occupational exposure to GA by inhalation is suspected of causing delayed irritating effects. In recent years, GA has emerged as the main cause of occupational asthma among health-care workers. The aim of the present study was to evaluate effects of GA inhalatory exposure (0.025 ppm or 0.1 ppm, for 28 days) in rats exposed corresponding to the occupational shift cycle, at time point 24 h, 48 h, and 7 days postexposure (PE). Numerous vacuoles and dilated spaces in epithelial cells in bronchioles showing a destructive effect of GA on the cellular membrane were observed at 24 h PE in 0.1 ppm exposed rats. Lipid vacuoles observed after 48 h PE in higher GA exposure, in the Clara cells of the bronchial epithelium, and in endothelial cells of the alveolar capillaries are probably attributable to disturbed lipid metabolism. Many foci of collagen fibers were observed already after 7 days postexposure. Monitoring of inflammatory response and repair was made possible by using two biomarkers: Clara-cell protein (CC16) and hyaluronic acid (HA). Our results show that the inflammatory repair response contributed to progenitor Clara cells and HA plays a role in the development of fibrotic changes in the lung of rats. Glutaraldehyde in rats causes fibrotic effects at the actual threshold limit value-time weighted average (TLV-TWA) level for GA as specified by current Polish and other national regulations.

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.

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. Copyright © 2016. Published by Elsevier B.V.

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

(2-methoxyethoxy)acetic acid: a urinary biomarker of exposure for jet fuel JP-8.

PubMed

B'hymer, Clayton; Mathias, Patricia; Krieg, Edward; Cheever, Kenneth L; Toennis, Christine A; Clark, John C; Kesner, James S; Gibson, Roger L; Butler, Mary Ann

2012-05-01

To demonstrate the utility of the urinary metabolite (2-methoxyethoxy)acetic acid (MEAA) as a biomarker of exposure. 2-(2-methoxyethoxy)ethanol [diethylene glycol monomethyl ether] is an anti-icing agent used in the formulation of JP-8, and it is added at a known uniform 0.1% (v/v) concentration to each batch lot. JP-8 is a kerosene-based fuel containing different compounds that vary in the content of every batch/lot of fuel; thus, MEAA has the potential to be a more specific and a consistent quantitative biomarker for JP-8 exposure. MEAA was used to measure exposure of jet propulsion fuel 8 (JP-8) in United States Air Force (USAF) personnel working at six airbases within the United States. Post-shift urine specimens from various personnel including high (n = 98), moderate (n = 38), and low (n = 61) exposure workgroup categories were collected and analyzed by a gas chromatographic-mass spectrometric test method. The three exposure groups were evaluated for the number per group positive for MEAA, and a statistical analysis consisted of pair-wise t-tests for unequal variances was used to test for the differences in mean MEAA concentrations between the exposure groups. The number of samples detected as positive for MEAA exposure, that is, those above the test method's limit of detection (LOD = 0.1 μg/ml), were 92 (93.9%), 13 (34.2%), and 2 (3.3%) for the high, moderate, and low exposure workgroup categories, respectively. The mean urinary MEAA level was significantly greater in the high exposure category (6.8 μg/ml), compared to the moderate (0.42 μg/ml) and the low (0.07 μg/ml) exposure categories. The maximum concentration of urinary MEAA was 110 μg/ml for the high exposure category, while 4.8 μg/ml and 0.2 μg/ml maximum levels were found in the moderate and low exposure categories, respectively. This study demonstrated that urinary MEAA can be used as an accurate biomarker of exposure for JP-8 workers and clearly distinguished the differences in JP-8

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

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.

Immortal time bias in drug safety cohort studies: spontaneous abortion following nonsteroidal antiinflammatory drug exposure.

PubMed

Daniel, Sharon; Koren, Gideon; Lunenfeld, Eitan; Levy, Amalia

2015-03-01

Experimental research of drug safety in pregnancy is generally not feasible because of ethical issues. Therefore, most of the information about drug safety in general and teratogenicity in particular is obtained through observational studies, which require careful methodologic design to obtain unbiased results. Immortal time bias occurs when some cases do not "survive" sufficient time in the study, and as such, they have reduced chances of being defined as "exposed" simply because the durations of their follow-ups were shorter. For example, studies that examine the risk for spontaneous abortions in women exposed to a drug during pregnancy are susceptible to immortal time bias because the chance of drug exposure increases the longer a pregnancy lasts. Therefore, the drug tested may falsely be found protective against the outcome tested. The objective of the current study was to illustrate the extent of immortal time bias using a cohort study of pregnancies assessing the risk for spontaneous abortions following nonsteroidal antiinflammatory drug exposure. We assembled 3 databases containing data on spontaneous abortions, births and drug dispensions to create the present study's cohort. The risk for spontaneous abortion was assessed using 2 statistical analysis methods that were compared for 2 definitions of exposure (dichotomous, exposed vs unexposed, regular Cox regression vs Cox regression with time-varying exposure). Significant differences were found in the risk for spontaneous abortions between the 2 statistical methods, both for groups and for most specific nonsteroidal antiinflammatory drugs (nonselective Cox inhibitors - hazard ratio, 0.70; 95% confidence interval, 0.61-0.94 vs hazard ratio, 1.10; 95% confidence interval, 0.99-1.22 for dichotomous vs time-varying exposure analyses, respectively). Furthermore, a significant correlation was found between the median misclassified immortal time for each drug and the extent of the bias. Immortal time bias can

Child and adolescent exposure to food and beverage brand appearances during prime-time television programming.

PubMed

Speers, Sarah E; Harris, Jennifer L; Schwartz, Marlene B

2011-09-01

The food industry disproportionately markets to young people through product placements. Children and adolescents may be more susceptible to these disguised persuasive attempts. Quantify incidence and youth exposure to food and beverage brand appearances within shows on prime-time TV. Data on the number of food, beverage, and restaurant brand appearances within shows during prime-time programming in 2008 were purchased from Nielsen and analyzed by product category and company in 2010. Exposure to these brand appearances by children, adolescents, and adults were examined and compared with exposure to prime-time TV advertisements for the same categories and companies using additional Nielsen data. Food, beverage, and restaurant brands appeared a total of 35,000 times within prime-time TV programming examined by Nielsen in 2008. Regular soft drinks, traditional restaurants (i.e., not quickserve), and energy/sports drinks made up 60% of all brand appearances. Young people viewed relatively few of these appearances with one notable exception. Coca-Cola products were seen 198 times by the average child and 269 times by the average adolescent during prime-time shows over the year, accounting for 70% of child exposure and 61% of adolescent exposure to brand appearances. One show, American Idol, accounted for more than 95% of these exposures. Exposure of children to Coca-Cola products through traditional advertisements was much less common. Brand appearances for most food industry companies, except for Coca-Cola, are relatively rare during prime-time programming with large youth audiences. Coca-Cola has pledged to refrain from advertising to children, yet the average child views almost four Coke appearances on prime-time TV every week. This analysis reveals a substantial, potential loophole in current food industry self-regulatory pledges to advertise only better-for-you foods to children. Copyright © 2011 American Journal of Preventive Medicine. Published by Elsevier Inc

Exposures and their determinants in radiographic film processing.

PubMed

Teschke, Kay; Chow, Yat; Brauer, Michael; Chessor, Ed; Hirtle, Bob; Kennedy, Susan M; Yeung, Moira Chan; Ward, Helen Dimich

2002-01-01

Radiographers process X-ray films using developer and fixer solutions that contain chemicals known to cause or exacerbate asthma. In a study in British Columbia, Canada, radiographers' personal exposures to glutaraldehyde (a constituent of the developer chemistry), acetic acid (a constituent of the fixer chemistry), and sulfur dioxide (a byproduct of sulfites, present in both developer and fixer solutions) were measured. Average full-shift exposures to glutaraldehyde, acetic acid, and sulfur dioxide were 0.0009 mg/m3, 0.09 mg/m3, and 0.08 mg/m3, respectively, all more than one order of magnitude lower than current occupational exposure limits. Local exhaust ventilation of the processing machines and use of silver recovery units lowered exposures, whereas the number of films processed per machine and the time spent near the machines increased exposures. Personnel in clinic facilities had higher exposures than those in hospitals. Private clinics were less likely to have local exhaust ventilation and silver recovery units. Their radiographers spent more time in the processor areas and processed more films per machine. Although exposures were low compared with exposure standards, there are good reasons to continue practices to minimize or eliminate exposures: glutaraldehyde and hydroquinone (present in the developer) are sensitizers; the levels at which health effects occur are not yet clearly established, but appear to be lower than current standards; and health effects resulting from the mixture of chemicals are not understood. Developments in digital imaging technology are making available options that do not involve wet-processing of photographic film and therefore could eliminate the use of developer and fixer chemicals altogether.

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.

The mammary gland is a sensitive pubertal target in CD-1 and C57Bl/6 mice following perinatal perfluorooctanoic acid (PFOA) exposure.

PubMed

Tucker, Deirdre K; Macon, Madisa B; Strynar, Mark J; Dagnino, Sonia; Andersen, Erik; Fenton, Suzanne E

2015-07-01

Perfluorooctanoic acid (PFOA) is a developmental toxicant in mice, with varied strain outcomes depending on dose and period of exposure. The impact of PFOA on female mouse pubertal development at low doses (≤1mg/kg) has yet to be determined. Therefore, female offspring from CD-1 and C57Bl/6 dams exposed to PFOA, creating serum concentrations similar to humans, were examined for pubertal onset, including mammary gland development. Pups demonstrated a shorter PFOA elimination half-life than that reported for adult mice. Prenatal exposure to PFOA caused significant mammary developmental delays in female offspring in both strains. Delays started during puberty and persisted into young adulthood; severity was dose-dependent. Also an evaluation of female serum hormone levels and pubertal timing onset revealed no effects of PFOA compared to controls in either strain. These data suggest that the mammary gland is more sensitive to early low level PFOA exposures compared to other pubertal endpoints, regardless of strain. Published by Elsevier Inc.

The effect of duration of exposure on sulfuric acid-induced pulmonary function changes in asthmatic adolescent subjects: A dose-response study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koenig, J.Q.; Covert, D.S.; Larson, T.V.

To evaluate the pulmonary effects of varying doses of sulfuric acid, adolescent subjects with asthma were exposed to 35 or 70 micrograms/m3 sulfuric acid for 45 or 90 min. Exposure was carried out during intermittent moderate exercise. The pulmonary functions measured before and after exposure were FEV1, FVC, and total respiratory resistance. The 45 min exposures were associated with larger decreases in FEV1 (-6% or -3%) than the 90 min exposures (-1% or +2%). Analysis of variance of the change in FEV1 among the exposures revealed that the 45 min exposure to 35 micrograms/m3 was significant (p = 0.03). Themore » p value for 45 min exposure to 70 micrograms/m3 was not significant (p = 0.08). Using analysis of variance, neither of the 90 min exposures was associated with a significant decrease in FEV1 compared to air exposure. Also, none of the changes in FVC or RT was significant. When baseline to post-exposure changes were compared for each of the five test atmospheres using paired t tests, both of the 45 min exposures were associated with statistical significance (p < 0.001 for 35 micrograms/m3 and p < 0.005 for 70 micrograms/m3). This baseline to post exposure change was not statistically significant for the 90 min exposures. The reason for the lesser effect on pulmonary function at increased exposure duration is not known; it may be due to changes in either varying deposition patterns or changes in buffering capacity of the cells lining the airways. With respect to individual sensitivities to H2SO4, the data showed a significant consistency across test atmospheres.« less

Exposure Time Distributions reveal Denitrification Rates along Groundwater Flow Path of an Agricultural Unconfined Aquifer

NASA Astrophysics Data System (ADS)

Kolbe, T.; Abbott, B. W.; Thomas, Z.; Labasque, T.; Aquilina, L.; Laverman, A.; Babey, T.; Marçais, J.; Fleckenstein, J. H.; Peiffer, S.; De Dreuzy, J. R.; Pinay, G.

2016-12-01

Groundwater contamination by nitrate is nearly ubiquitous in agricultural regions. Nitrate is highly mobile in groundwater and though it can be denitrified in the aquifer (reduced to inert N2 gas), this process requires the simultaneous occurrence of anoxia, an electron donor (e.g. organic carbon, pyrite), nitrate, and microorganisms capable of denitrification. In addition to this the ratio of the time groundwater spent in a denitrifying environment (exposure time) to the characteristic denitrification reaction time plays an important role, because denitrification can only occur if the exposure time is longer than the characteristic reaction time. Despite a long history of field studies and numerical models, it remains exceedingly difficult to measure or model exposure times in the subsurface at the catchment scale. To approach this problem, we developed a unified modelling approach combining measured environmental proxies with an exposure time based reactive transport model. We measured groundwater age, nitrogen and sulfur isotopes, and water chemistry from agricultural wells in an unconfined aquifer in Brittany, France, to quantify changes in nitrate concentration due to dilution and denitrification. Field data showed large differences in nitrate concentrations among wells, associated with differences in the exposure time distributions. By constraining a catchment-scale characteristic reaction time for denitrification with water chemistry proxies and exposure times, we were able to assess rates of denitrification along groundwater flow paths. This unified modeling approach is transferable to other catchments and could be further used to investigate how catchment structure and flow dynamics interact with biogeochemical processes such as denitrification.

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.

Asthmatic responses to airborne acid aerosols

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ostro, B.D.; Lipsett, M.J.; Wiener, M.B.

1991-06-01

Controlled exposure studies suggest that asthmatics may be more sensitive to the respiratory effects of acidic aerosols than individuals without asthma. This study investigates whether acidic aerosols and other air pollutants are associated with respiratory symptoms in free-living asthmatics. Daily concentrations of hydrogen ion (H+), nitric acid, fine particulates, sulfates and nitrates were obtained during an intensive air monitoring effort in Denver, Colorado, in the winter of 1987-88. A panel of 207 asthmatics recorded respiratory symptoms, frequency of medication use, and related information in daily diaries. We used a multiple regression time-series model to analyze which air pollutants, if any,more » were associated with health outcomes reported by study participants. Airborne H+ was found to be significantly associated with several indicators of asthma status, including moderate or severe cough and shortness of breath. Cough was also associated with fine particulates, and shortness of breath with sulfates. Incorporating the participants' time spent outside and exercise intensity into the daily measure of exposure strengthened the association between these pollutants and asthmatic symptoms. Nitric acid and nitrates were not significantly associated with any respiratory symptom analyzed. In this population of asthmatics, several outdoor air pollutants, particularly airborne acidity, were associated with daily respiratory symptoms.« less

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...

Effect of Timing of Proton Pump Inhibitor Administration on Acid Suppression.

PubMed

Furuta, Kenji; Adachi, Kyoichi; Aimi, Masahito; Shimura, Shino; Mikami, Hironobu; Nishimura, Nobuhiro; Ishimura, Norihisa; Ishihara, Shunji; Naora, Kohji; Kinoshita, Yoshikazu

2016-01-01

Esomeprazole has been reported to show a strong acid suppression following preprandial as compared to postprandial administration, though no known study has compared the acid suppressing effects of other proton pump inhibitors between those administrations. The aim of this study was to compare intragastric pH levels following pre- and postprandial administrations of rabeprazole and esomeprazole. In 15 Helicobacter pylori-negative healthy volunteers, we measured intragastric pH after 7 days of pre- and postprandial administrations of rabeprazole (10 mg) or esomeprazole (20 mg) using a 5-way crossover design. Preprandial administration of esomeprazole showed stronger acid suppression than postprandial administration. The values for percent time at pH >4.0 over a 24-hour period increased from 45.3% with postprandial administration of esomeprazole to 54.4% with preprandial administration, while the percent time at pH >4.0 during daytime was increased to a greater extent from 51.4 to 66.5% with preprandial administration (p = 0.05). On the other hand, the acid suppressing effect of rabeprazole was not influenced by the timing of administration. The acid suppressing effect of esomeprazole is influenced by administration timing. In contrast, the acid suppressing effect of rabeprazole is not augmented by preprandial administration. © 2015 S. Karger AG, Basel.

Degradation study of carnosic acid, carnosol, rosmarinic acid, and rosemary extract (Rosmarinus officinalis L.) assessed using HPLC.

PubMed

Zhang, Ying; Smuts, Jonathan P; Dodbiba, Edra; Rangarajan, Rekha; Lang, John C; Armstrong, Daniel W

2012-09-12

Rosemary, whose major caffeoyl-derived and diterpenoid ingredients are rosmarinic acid, carnosol, and carnosic acid, is an important source of natural antioxidants and is being recognized increasingly as a useful preservative, protectant, and even as a potential medicinal agent. Understanding the stability of these components and their mode of interaction in mixtures is important if they are to be utilized to greatest effect. A study of the degradation of rosmarinic acid, carnosol, carnosic acid, and a mixture of the three was conducted in ethanolic solutions at different temperatures and light exposure. As expected, degradation increased with temperature. Some unique degradation products were formed with exposure to light. Several degradation products were reported for the first time. The degradation products were identified by HPLC/MS/MS, UV, and NMR. The degradation of rosemary extract in fish oil also was investigated, and much slower rates of degradation were observed for carnosic acid. In the mixture of the three antioxidants, carnosic acid serves to maintain levels of carnosol, though it does so at least in part at the cost of its own degradation.

An accurate laser radiometer for determining visible exposure times.

PubMed

Royston, D D

1985-01-01

A laser light radiometer has been developed for the Electro-Optics Branch of the Center for Devices and Radiological Health (CDRH). The radiometer measures direct laser radiation emitted in the visible spectrum. Based upon this measurement, the instrument's microprocessor automatically determines at what time duration the exposure to the measured laser radiation would exceed either the class I accessible emission limits of the Federal Performance Standard for laser products or the maximum permissible exposure limits of laser user safety standards. The instrument also features automatic background level compensation, pulse measurement capability, and self-diagnosis. Measurement of forward surface illumination levels preceding HpD photoradiation therapy is possible.

Beneficial effects of garlic on learning and memory deficits and brain tissue damages induced by lead exposure during juvenile rat growth is comparable to the effect of ascorbic acid.

PubMed

Ghasemi, Simagol; Hosseini, Mahmoud; Feizpour, Azadeh; Alipour, Fatemeh; Sadeghi, Akram; Vafaee, Farzaneh; Mohammadpour, Toktam; Soukhtanloo, Mohammad; Ebrahimzadeh Bideskan, Alireza; Beheshti, Farimah

2017-04-01

The neuroprotective effects of both garlic and ascorbic acid (AA) have been documented. In this study the effects of garlic and ascorbic acid on memory deficits and brain tissue oxidative damages induced by lead exposure was investigated. The juvenile rats were divided and treated: (1) Control, (2) Lead (lead acetate in drinking water, 8 weeks), (3) Lead - Ascorbic Acid (Lead-AA), (4)  Lead - Garlic (100 mg/kg, daily, gavage) (Lead-Gar). In Morris water maze (MWM), the escape latency and traveled path in the Lead group were significantly higher while, the time spent in the target quadrant (Q1) was lower than Control. Both Lead-Gar and Lead-AA groups spent more times in Q1than to lead group. There were no significant differences in swimming speed between the groups. In passive avoidance (PA) test, the time latency for entering the dark compartment by Lead group was lower than Control. Treatment of the animals by AA and garlic significantly increased the time latency. In Lead group, the total thiol concentration in brain tissues was significantly lower while, MDA was higher than Control. Treatment by both garlic and AA increased total thiol concentrations and decreased MDA. Both garlic and AA decreased the lead content of brain tissues. It is suggested that treatment with garlic attenuates the learning and memory impairments due to lead exposure during juvenile rat growth which is comparable to AA. The possible mechanism may be due to its protective effects against brain tissues oxidative damage as well the lowering effects of brain lead content.

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 (...

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.

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. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

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).

Effects of chronic exposure to soft, acidic water on gill development and chloride cell numbers in embryo-larval brook trout, Salvelinus fontinalis

USGS Publications Warehouse

Conklin, D.J.; Mowbray, R.C.; Gingerich, W.H.

1992-01-01

Recruitment failure is considered to be a major factor contributing to the decline of fish populations in soft, acidic waters; direct mortality of embryo-larval fishes has been postulated as a major cause of the decline. Little is understood of the physiological consequences to embryo-larval fishes of prolonged exposure to soft, acidic waters; however, dysfunction of respiratory and ionoregulatory processes is suspected. In order to evaluate the effects of acid exposure on the respiratory and ionoregulatory systems of developing brook trout, Salvelinus fontinalis, differences in gill morphology and numbers of chloride cells were compared between groups cf developing embryo-larval fish continuously exposed to moderately hard well water (130.0 mg.l-1 as CaCO3, pH 7.94) or to reconstituted soft, acidic water (4.4 mg.l-1 as CaCO3, pH 5.25) designed to mimic acidic waters of northern Wisconsin acidified lakes. Exposures were maintained for up to 48 days (82 days after fertilization) during critical periods of growth and differentiation of branchial structures. The second right gill arch of each fish was examined for changes in the development of filaments and lamellae and for differences in numbers of chloride cells. Gills of fish that developed in soft, acidic water contained greater numbers of normal and degenerating chloride cells, exhibited hyperplasia of primary epithelium and multiple fusions of adjacent filaments and lamellar epithelium than the gills of control fish. Filament and lamellar lengths and numbers of lamellae per filament were significantly less (P< 0.05) in fish that developed in soft, acidic water than in fish exposed to well water.

Biomarkers of Exposure to Toxic Substances: Volume 4: Metabonomics Biomarkers to Liver and Organ Damage

DTIC Science & Technology

2009-05-01

examined the urinary metabolite profiles from rats following a single exposure to the kidney toxicants D- serine, puromycin, hippuric acid and...15. SUBJECT TERMS Amphotericin B, bioinformatics, cell cycle regulation, clinical, clustering analysis, D-serine, glomerular injury, hippuric acid ...puromycin, hippuric acid and amphotericin B at various doses, and as a function of time post-dose. In toxicology, such dose-time metabonomics studies are

Sleep disorders and the prevalence of asymptomatic nocturnal acid and non-acid reflux.

PubMed

Herdman, Christine; Marzio, Dina Halegoua-De; Shah, Paurush; Denuna-Rivera, Susie; Doghramji, Karl; Cohen, Sidney; Dimarino, Anthony J

2013-01-01

Nocturnal acid reflux is associated with symptomatic and asymptomatic sleep arousals, leading to fragmented sleep. The frequency and influence of acid reflux in patients with various forms of insomnia has not been reported. The aim of this study was to quantify nocturnal acid and nonacid reflux in patients with primary sleep disorders as previously diagnosed by polysomnography. THIRTY ONE SUBJECTS WERE STUDIED: (A) 9 subjects with a polysomnographically diagnosed sleep disorder (1 with restless legs syndrome, 4 with narcolepsy, 4 with periodic limb movement disorder); (B) 12 subjects with primary insomnia (PI) and unrevealing polysomnography; and (C) 10 controls without disturbed sleep. All subjects underwent a physical examination and 24 h transnasal pH and impedance monitoring to detect acid and non-acid reflux. The 21 subjects with fragmented sleep due to a primary sleep disorder had significantly more recumbent acid exposure (>1.2% of time) as compared with control subjects (33% versus 0%). When fragmented sleep subjects were divided into two groups, 17% of PI subjects and 55% of subjects with a diagnosed sleep disorder had significant recumbent acid exposure (P=0.009). Likewise, the median recumbent nonacid events were increased in the sleep disordered group (P=0.011). This study indicates that patients with primary sleep disorders have prominent nocturnal acid reflux without symptoms of daytime acid reflux. Acid reflux is most prominent in patients with polysomnographic findings of disturbed sleep as compared to patients with PI; while non acid reflux is increased minimally in these patients.

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

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 ...

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...

Estimating time-varying exposure-outcome associations using case-control data: logistic and case-cohort analyses.

PubMed

Keogh, Ruth H; Mangtani, Punam; Rodrigues, Laura; Nguipdop Djomo, Patrick

2016-01-05

Traditional analyses of standard case-control studies using logistic regression do not allow estimation of time-varying associations between exposures and the outcome. We present two approaches which allow this. The motivation is a study of vaccine efficacy as a function of time since vaccination. Our first approach is to estimate time-varying exposure-outcome associations by fitting a series of logistic regressions within successive time periods, reusing controls across periods. Our second approach treats the case-control sample as a case-cohort study, with the controls forming the subcohort. In the case-cohort analysis, controls contribute information at all times they are at risk. Extensions allow left truncation, frequency matching and, using the case-cohort analysis, time-varying exposures. Simulations are used to investigate the methods. The simulation results show that both methods give correct estimates of time-varying effects of exposures using standard case-control data. Using the logistic approach there are efficiency gains by reusing controls over time and care should be taken over the definition of controls within time periods. However, using the case-cohort analysis there is no ambiguity over the definition of controls. The performance of the two analyses is very similar when controls are used most efficiently under the logistic approach. Using our methods, case-control studies can be used to estimate time-varying exposure-outcome associations where they may not previously have been considered. The case-cohort analysis has several advantages, including that it allows estimation of time-varying associations as a continuous function of time, while the logistic regression approach is restricted to assuming a step function form for the time-varying association.

Biomarkers of environmental benzene exposure.

PubMed Central

Weisel, C; Yu, R; Roy, A; Georgopoulos, P

1996-01-01

Environmental exposures to benzene result in increases in body burden that are reflected in various biomarkers of exposure, including benzene in exhaled breath, benzene in blood and urinary trans-trans-muconic acid and S-phenylmercapturic acid. A review of the literature indicates that these biomarkers can be used to distinguish populations with different levels of exposure (such as smokers from nonsmokers and occupationally exposed from environmentally exposed populations) and to determine differences in metabolism. Biomarkers in humans have shown that the percentage of benzene metabolized by the ring-opening pathway is greater at environmental exposures than that at higher occupational exposures, a trend similar to that found in animal studies. This suggests that the dose-response curve is nonlinear; that potential different metabolic mechanisms exist at high and low doses; and that the validity of a linear extrapolation of adverse effects measured at high doses to a population exposed to lower, environmental levels of benzene is uncertain. Time-series measurements of the biomarker, exhaled breath, were used to evaluate a physiologically based pharmacokinetic (PBPK) model. Biases were identified between the PBPK model predictions and experimental data that were adequately described using an empirical compartmental model. It is suggested that a mapping of the PBPK model to a compartmental model can be done to optimize the parameters in the PBPK model to provide a future framework for developing a population physiologically based pharmacokinetic model. PMID:9118884

Cadmium and mercury exposure over time in Swedish children

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lundh, T., E-mail: Thomas.Lundh@med.lu.se

Purpose: Knowledge about changes in exposure to toxic metals over time remains very sparse, in particular for children, the most vulnerable group. Here, we assessed whether a reduction in environmental pollution with cadmium (Cd) and mercury (Hg) caused a change in exposure over time. In total, 1257 children (age 4–9) in two towns in Sweden were sampled once in 1986–2013. Blood concentrations of Cd (b-Cd; n=1120) and Hg (b-Hg; n=560) were determined. Results: The median b-Cd was 0.10 (geometric mean 0.10; range 0.010–0.61) μg/L and b-Hg was 0.91 (geometric mean 0.83; range 0.021–8.2) μg/L. Children living close to a smeltermore » had higher b-Cd and b-Hg than those in urban and rural areas. There was no sex difference in b-Cd or b-Hg, and b-Cd and b-Hg showed no significant accumulation by age. b-Cd decreased only slightly (0.7% per year, p<0.001) over the study period. In contrast, b-Hg did show a clear decrease over the study period (3% per year, p<0.001). Conclusions: The exposure to Cd was very low but still might increase the risk of disease later in life. Moreover, b-Cd only showed a minor decrease, indicating that Cd pollution should be further restricted. b-Hg was relatively low and decreasing, probably because of reduced use of dental amalgam and lower Hg intake from fish. The b-Cd and b-Hg levels decreased much less than the levels of lead in the blood as previously found in the same children. - Highlights: • There are few studies of time trends for exposure to toxic metals, except for lead. • 1986–2013 we studied blood levels of cadmium and mercury in 1257 Swedish children. • The median blood concentration of cadmium was 0.10 μg/L, of mercury 0.83 μg/L. • Cadmium perhaps decreased by 0.7% per year, mercury by 3% per year. • Cadmium accumulation may result in toxic levels in elderly women.« less

Perfluorooctanoic acid exposure induces endoplasmic reticulum stress in the liver and its effects are ameliorated by 4-phenylbutyrate.

PubMed

Yan, Shengmin; Zhang, Hongxia; Wang, Jianshe; Zheng, Fei; Dai, Jiayin

2015-10-01

Perfluoroalkyl acids (PFAAs) are a group of widely used anthropogenic compounds. As one of the most dominant PFAAs, perfluorooctanoic acid (PFOA) has been suggested to induce hepatotoxicity and several other toxicological effects. However, details on the mechanisms for PFOA-induced hepatotoxicity still need to be elucidated. In this study, we observed the occurrence of endoplasmic reticulum (ER) stress in mouse livers and HepG2 cells after PFOA exposure using several familiar markers for the unfolded protein response (UPR). ER stress in HepG2 cells after PFOA exposure was not significantly influenced by autophagy inhibition or stimulation. The antioxidant defense system was significantly disturbed in mouse livers after PFOA exposure, and reactive oxygen species (ROS) were increased in cells exposed to PFOA for 24 h. However, N-acetyl-L-cysteine (NAC) pretreatment did not satisfactorily alleviate the UPR in cells exposed to PFOA even though the increase of ROS was less evident. Furthermore, exposure of HepG2 cells to PFOA in the presence of sodium 4-phenylbutyrate (4-PBA), a chemical chaperone and ER stress inhibitor, suggested that 4-PBA alleviated the UPR and autophagosome accumulation induced by PFOA in cells. In addition, several toxicological effects attributed to PFOA exposure, including cell cycle arrest, proteolytic activity impairment, and neutral lipid accumulation, were also improved by 4-PBA cotreatment in cells. In vivo study demonstrated that PFOA-induced lipid metabolism perturbation and liver injury were partially ameliorated by 4-PBA in mice after 28 days of exposure. These findings demonstrated that PFOA-induced ER stress leading to UPR might play an important role in PFOA-induced hepatotoxic effects, and chemical chaperone 4-PBA could ameliorate the effects. Copyright © 2015. Published by Elsevier Inc.

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

Induction of Salivary Proteins Modifies Measures of Both Orosensory and Postingestive Feedback during Exposure to a Tannic Acid Diet

PubMed Central

Torregrossa, Ann-Marie; Nikonova, Larissa; Bales, Michelle B.; Villalobos Leal, Maria; Smith, James C.; Contreras, Robert J.; Eckel, Lisa A.

2014-01-01

There are hundreds of proteins in saliva. Although it has long been hypothesized that these proteins modulate taste by interacting with taste receptors or taste stimuli, the functional impact of these proteins on feeding remains relatively unexplored. We have developed a new technique for saliva collection that does not interfere with daily behavioral testing and allows us to explore the relationship between feeding behavior and salivary protein expression. First, we monitored the alterations in salivary protein expression while simultaneously monitoring the animals' feeding behavior and meal patterns on a custom control diet or on the same diet mixed with 3% tannic acid. We demonstrated that six protein bands increased in density with dietary tannic acid exposure. Several of these bands were significantly correlated with behaviors thought to represent both orosensory and postingestive signaling. In a follow-up experiment, unconditioned licking to 0.01–3% tannic acid solutions was measured during a brief-access taste test before and after exposure to the tannic acid diet. In this experiment, rats with salivary proteins upregulated found the tannin solution less aversive (i.e., licked more) than those in the control condition. These data suggest a role for salivary proteins in mediating changes in both orosensory and postingestive feedback. PMID:25162297

Effects of day-time exposure to different light intensities on light-induced melatonin suppression at night.

PubMed

Kozaki, Tomoaki; Kubokawa, Ayaka; Taketomi, Ryunosuke; Hatae, Keisuke

2015-07-04

Bright nocturnal light has been known to suppress melatonin secretion. However, bright light exposure during the day-time might reduce light-induced melatonin suppression (LIMS) at night. The effective proportion of day-time light to night-time light is unclear; however, only a few studies on accurately controlling both day- and night-time conditions have been conducted. This study aims to evaluate the effect of different day-time light intensities on LIMS. Twelve male subjects between the ages of 19 and 23 years (mean ± S.D., 20.8 ± 1.1) gave informed consent to participate in this study. They were exposed to various light conditions (<10, 100, 300, 900 and 2700 lx) between the hours of 09:00 and 12:00 (day-time light conditions). They were then exposed to bright light (300 lx) again between 01:00 and 02:30 (night-time light exposure). They provided saliva samples before (00:55) and after night-time light exposure (02:30). A one-tailed paired t test yielded significant decrements of melatonin concentration after night-time light exposure under day-time dim, 100- and 300-lx light conditions. No significant differences exist in melatonin concentration between pre- and post-night-time light exposure under day-time 900- and 2700-lx light conditions. Present findings suggest the amount of light exposure needed to prevent LIMS caused by ordinary nocturnal light in individuals who have a general life rhythm (sleep/wake schedule). These findings may be useful in implementing artificial light environments for humans in, for example, hospitals and underground shopping malls.

Genotoxic effects of boric acid and borax in zebrafish, Danio rerio using alkaline comet assay

PubMed Central

Gülsoy, Nagihan; Yavas, Cüneyd; Mutlu, Özal

2015-01-01

The present study is conducted to determine the potential mechanisms of Boron compounds, boric acid (BA) and borax (BX), on genotoxicity of zebrafish Danio rerio for 24, 48, 72 and 96-hours acute exposure (level:1, 4, 16, 64 mg/l BA and BX) in semi-static bioassay experiment. For that purpose, peripheral erythrocytes were drawn from caudal vein and Comet assay was applied to assess genotoxicity. Acute (96 hours) exposure and high concentrations of boric acid and borax increases % tail DNA and Olive tail moment. Genotoxicity was found for BA as concentration-dependent and BX as concentration and time dependent manner. In general, significant effects (P < 0,05) on both concentrations and exposure times were observed in experimental groups. DNA damage was highest at 96 h and 24 h for all BX and BA concentrations, respectively in peripheral blood of D. rerio. For the first time, our study demonstrates the effect of waterborne BA and BX exposure on genotoxicity at the molecular level, which may contribute to understanding the mechanism of boric acid and borax-induced genotoxicity in fish. PMID:26862320

Genotoxic effects of boric acid and borax in zebrafish, Danio rerio using alkaline comet assay.

PubMed

Gülsoy, Nagihan; Yavas, Cüneyd; Mutlu, Özal

2015-01-01

The present study is conducted to determine the potential mechanisms of Boron compounds, boric acid (BA) and borax (BX), on genotoxicity of zebrafish Danio rerio for 24, 48, 72 and 96-hours acute exposure (level:1, 4, 16, 64 mg/l BA and BX) in semi-static bioassay experiment. For that purpose, peripheral erythrocytes were drawn from caudal vein and Comet assay was applied to assess genotoxicity. Acute (96 hours) exposure and high concentrations of boric acid and borax increases % tail DNA and Olive tail moment. Genotoxicity was found for BA as concentration-dependent and BX as concentration and time dependent manner. In general, significant effects (P < 0,05) on both concentrations and exposure times were observed in experimental groups. DNA damage was highest at 96 h and 24 h for all BX and BA concentrations, respectively in peripheral blood of D. rerio. For the first time, our study demonstrates the effect of waterborne BA and BX exposure on genotoxicity at the molecular level, which may contribute to understanding the mechanism of boric acid and borax-induced genotoxicity in fish.

Real time non invasive imaging of fatty acid uptake in vivo

PubMed Central

Henkin, Amy H.; Cohen, Allison S.; Dubikovskaya, Elena A.; Park, Hyo Min; Nikitin, Gennady F.; Auzias, Mathieu G.; Kazantzis, Melissa; Bertozzi, Carolyn R.; Stahl, Andreas

2012-01-01

Detection and quantification of fatty acid fluxes in animal model systems following physiological, pathological, or pharmacological challenges is key to our understanding of complex metabolic networks as these macronutrients also activate transcription factors and modulate signaling cascades including insulin-sensitivity. To enable non-invasive, real-time, spatiotemporal quantitative imaging of fatty acid fluxes in animals, we created a bioactivatable molecular imaging probe based on long-chain fatty acids conjugated to a reporter molecule (luciferin). We show that this probe faithfully recapitulates cellular fatty acid uptake and can be used in animal systems as a valuable tool to localize and quantitate in real-time lipid fluxes such as intestinal fatty acid absorption and brown adipose tissue activation. This imaging approach should further our understanding of basic metabolic processes and pathological alterations in multiple disease models. PMID:22928772

A simple exposure-time theory for all time-nonlocal transport formulations and beyond.

NASA Astrophysics Data System (ADS)

Ginn, T. R.; Schreyer, L. G.

2016-12-01

Anomalous transport or better put, anomalous non-transport, of solutes or flowing water or suspended colloids or bacteria etc. has been the subject of intense analyses with multiple formulations appearing in scientific literature from hydrology to geomorphology to chemical engineering, to environmental microbiology to mathematical physics. Primary focus has recently been on time-nonlocal mass conservation formulations such as multirate mass transfer, fractional-time advection-dispersion, continuous-time random walks, and dual porosity modeling approaches, that employ a convolution with a memory function to reflect respective conceptual models of delays in transport. These approaches are effective or "proxy" ones that do not always distinguish transport from immobilzation delays, are generally without connection to measurable physicochemical properties, and involve variously fractional calculus, inverse Laplace or Fourier transformations, and/or complex stochastic notions including assumptions of stationarity or ergodicity at the observation scale. Here we show a much simpler approach to time-nonlocal (non-)transport that is free of all these things, and is based on expressing the memory function in terms of a rate of mobilization of immobilized mass that is a function of the continguous time immobilized. Our approach treats mass transfer completely independently from the transport process, and it allows specification of actual immobilization mechanisms or delays. To our surprize we found that for all practical purposes any memory function can be expressed this way, including all of those associated with the multi-rate mass transfer approaches, original powerlaw, different truncated powerlaws, fractional-derivative, etc. More intriguing is the fact that the exposure-time approach can be used to construct heretofore unseen memory functions, e.g., forms that generate oscillating tails of breakthrough curves such as may occur in sediment transport, forms for delay

Perfluoroalkyl acids in children and their mothers: Association with drinking water and time trends of inner exposures--Results of the Duisburg birth cohort and Bochum cohort studies.

PubMed

Wilhelm, Michael; Wittsiepe, Jürgen; Völkel, Wolfgang; Fromme, Hermann; Kasper-Sonnenberg, Monika

2015-10-01

Perfluoroalkyl acids (PFAAs) are widely distributed in the environment and humans are globally exposed with them. Contaminated drinking water can considerably contribute to the inner exposure levels. We report the results of a human biomonitoring study with mother-child pairs living in two German cities, one city with PFAA contaminated drinking water in the sub μg/l-range (Bochum) and the other one without contamination (Duisburg). Furthermore, we studied time trends of exposure levels within the Duisburg cohort study. We measured seven PFAAs (PFOS, PFOA, PFHxS, PFNA, PFBS, PFDeA, PFDoA) in blood samples by high performance liquid chromatography and tandem mass spectrometry. Samples were taken during pregnancy, from umbilical cord blood (2000-2002), 6-7 years (5th follow-up) and 8-10 years after birth (7th follow-up). The consumption of drinking water was recorded by a standardized questionnaire. Statistical analyses were calculated with multiple linear regression models. Children and mothers from Bochum showed higher PFOS and PFOA plasma concentrations than from Duisburg. The median concentrations (μg/l) for children were: PFOS 4.7 vs. 3.3; PFOA 6.0 vs. 3.6μg/l (p≤0.05). Consumption of >0.7 l (children) and >0.9 l (mothers) drinking water/day was associated with 13-18% higher PFOS, PFOA and PFHxS concentrations in children (p≤0.01), and 22% higher PFOA in mothers (p≤0.05). Within the Duisburg cohort, PFAA levels in children peaked in the 5th follow-up study (medians (μg/l): cord plasma: 2.7 (PFOS); 1.9 (PFOA); 5th follow-up: 3.6 (PFOS); 4.6 (PFOA); 7th follow-up: 3.3 (PFOS); 3.6 (PFOA)). PFOS concentrations in mothers declined from pregnancy to the 5th follow-up (medians: 8.7 vs. 4.0μg/l). Residents exposed to PFOS and PFOA through drinking water showed significantly higher PFOS and PFOA concentrations in blood plasma. Although PFAA concentrations in the children slightly decreased from the 5th to the 7th follow-up, we detected increasing exposure

The role of CO2 variability and exposure time for biological impacts of ocean acidification

NASA Astrophysics Data System (ADS)

Shaw, Emily C.; Munday, Philip L.; McNeil, Ben I.

2013-09-01

impacts of ocean acidification have mostly been studied using future levels of CO2 without consideration of natural variability or how this modulates both duration and magnitude of CO2 exposure. Here we combine results from laboratory studies on coral reef fish with diurnal in situ CO2 data from a shallow coral reef, to demonstrate how natural variability alters exposure times for marine organisms under increasingly high-CO2 conditions. Large in situ CO2 variability already results in exposure of coral reef fish to short-term CO2 levels higher than laboratory-derived critical CO2 levels (~600 µatm). However, we suggest that the in situ exposure time is presently insufficient to induce negative effects observed in laboratory studies. Our results suggest that both exposure time and the magnitude of CO2 levels will be important in determining the response of organisms to future ocean acidification, where both will increase markedly with future increases in CO2.

Cognitive effects of radiation emitted by cellular phones: the influence of exposure side and time.

PubMed

Luria, Roy; Eliyahu, Ilan; Hareuveny, Ronen; Margaliot, Menachem; Meiran, Nachshon

2009-04-01

This study examined the time dependence effects of exposure to radiofrequency radiation (RFR) emitted by standard GSM cellular phones on the cognitive functions of humans. A total of 48 healthy right-handed male subjects performed a spatial working memory task (that required either a left-hand or a right-hand response) while being exposed to one of two GSM phones placed at both sides of the head. The subjects were randomly divided into three groups. Each group was exposed to one of three exposure conditions: left-side of the head, right-side, or sham-exposure. The experiment consisted of 12 blocks of trials. Response times (RTs) and accuracy of the responses were recorded. It was found that the average RT of the right-hand responses under left-side exposure condition was significantly longer than those of the right-side and sham-exposure groups averaged together during the first two time blocks. These results confirmed the existence of an effect of exposure on RT, as well as the fact that exposure duration (together with the responding hand and the side of exposure) may play an important role in producing detectable RFR effects on performance. Differences in these parameters might be the reason for the failure of certain studies to detect or replicate RFR effects. (c) 2008 Wiley-Liss, Inc.

Chemical nature and immunotoxicological properties of arachidonic acid degradation products formed by exposure to ozone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Madden, M.C.; Friedman, M.; Hanley, N.

1993-06-01

Ozone (O3) exposure in vivo has been reported to degrade arachidonic acid (AA) in the lungs of rodents. The O3-degraded AA products may play a role in the responses to this toxicant. To study the chemical nature and biological activity of O3-exposed AA, we exposed AA in a cell-free, aqueous environment to air, 0.1 ppm O3, or 1.0 ppm O3 for 30-120 min. AA exposed to air was not degraded. All O3 exposures degraded > 98% of the AA to more polar products, which were predominantly aldehydic substances (as determined by reactivity with 2,4-dinitrophenylhydrazine and subsequent separation by HPLC) andmore » hydrogen peroxide. The type and amount of aldehydic substances formed depended on the O3 concentration and exposure duration. A human bronchial epithelial cell line (BEAS-2B, S6 subclone) exposed in vitro to either 0.1 ppm or 1.0 ppm O3 for 1 hr produced AA-derived aldehydic substances, some of which eluted with similar retention times as the aldehydic substances derived from O3 degradation of AA in the cell-free system. In vitro, O3-degraded AA induced an increase in human peripheral blood polymorphonuclear leukocyte (PMN) polarization, decreased human peripheral blood T-lymphocyte proliferation in response to mitogens, and decreased human peripheral blood natural killer cell lysis of K562 target cells. The aldehydic substances, but not hydrogen peroxide, appeared to be the principal active agents responsible for the observed effects. O3-degraded AA may play a role in the PMN influx into lungs and in decreased T-lymphocyte mitogenesis and natural killer cell activity observed in humans and rodents exposed to O3.« less

The mammary gland is a sensitive pubertal target in CD-1 and C57Bl/6 mice following perinatal perfluorooctanoic acid (PFOA) exposure

PubMed Central

Tucker, Deirdre K.; Macon, Madisa B.; Strynar, Mark J.; Dagnino, Sonia; Andersen, Erik; Fenton, Suzanne E.

2015-01-01

Perfluorooctanoic acid (PFOA) is a known developmental toxicant in mice, with varied strain outcomes depending on dose and period of exposure. The impact of PFOA on female mouse pubertal development at low doses (≤1 mg/kg), however, has yet to be determined. Therefore, female offspring from CD-1 and C57Bl/6 dams exposed to PFOA, creating serum concentrations similar to humans, were examined for pubertal onset, including mammary gland development. Mouse pups demonstrated a shorter PFOA elimination half-life than that reported for adult mice. Prenatal exposure to PFOA caused significant mammary developmental delays in exposed female offspring in both strains. Delays started during puberty and persisted into young adulthood; severity was dose-dependent. In contrast, an evaluation of serum hormone levels and pubertal timing onset in the same offspring revealed no effects of PFOA compared to controls in either strain. Therefore, our data suggest that the mammary gland is more sensitive to the effects of early low level PFOA exposures compared to other pubertal endpoints, regardless of strain. PMID:25499722

HISTOPATHOLOGICAL ANALYSIS OF THE F344 RAT LUNG UPON EXPOSURE TO RETENOIC ACID, OVALBUMIN, MOLD SPORES AND CITRAL.

PubMed

Farah, Ibrahim O; Holt-Gray, Carlene; Cameron, Joseph A; Tucci, Michelle; Benghuzzi, Hamed

2017-01-01

The paradoxical role of retinoic acid (All Trans Retinoic Acid; ATRA) in the development of allergic and/or inflammatory complications in contrast to a therapeutic modality for lung pathology is not well understood or established in the literature. As well, the role of Citral (inhibitor of retinoid function; a non-toxic chemical that exists in two forms (diethyl; C1 or cis-trans dimethyl; C2), in the reversal of retinoic acid, ovalbumin and allergic mold spore pathophysiology is also not well ascertained under an in vivo setting. Therefore, it is hypothesized that exposure of F344 lung tissues to supra-physiologic levels of retinoic acid, ovalbumin and mold spores individually or in combination with each other will lead to inflammatory tissue pathology and that Citral 1 and 2 will reverse or ameliorate the related pathological damage to lung tissues. Even though ovalbumin and retinoic acid have been previously applied through intra-tracheal route in cancer prevention and immunological research, the objective of this study was to evaluate the histopathological implications of such exposure in vivo. This IACUC approved in vivo study used Fischer 344 rats ( n = 80 ; 229 to 273g), which were randomly assigned to controls as well as ovalbumin and mold-sensitized treatment groups (0.80 mg/kg and 1×10 9 mold spores combined from 4 strains/100 μl intra-tracheal; all others were dosed by intra-peritoneal injection at days 1 and 7 with 80 mg/kg each of ATRA as well as 20 and 50 mg/kg each of Citrals 1 or 2 individually or in combination to represent all four chemicals and mold spores treatments. Positive and negative controls for each treatment were also included in the study. Animals were housed in rat cages at the JSU Research Animal Core Facilities and were placed on a 12:12 light-dark cycle. A standard rodent diet and water access were provided ad libidum. All animals were sacrificed on day 21 and lung tissues were processed for histopathology. Slides were prepared and

Acidosis counteracts itch tachyphylaxis to consecutive pruritogen exposure dependent on acid-sensing ion channel 3.

PubMed

Jiang, Yi-Ming; Huang, Chen; Peng, Zhong; Han, Shao-Ling; Li, Wei-Guang; Zhu, Michael Xi; Xu, Tian-Le

2017-01-01

Tachyphylaxis of itch refers to a markedly reduced scratching response to consecutive exposures of a pruritogen, a process thought to protect against tissue damage by incessant scratching and to become disrupted in chronic itch. Here, we report that a strong stimulation of the Mas-related G-protein-coupled receptor C11 by its agonist, Ser-Leu-Ile-Gly-Arg-Leu-NH 2 (SL-NH 2 ) or bovine adrenal medulla 8-22 peptide, via subcutaneous injection in mice induces tachyphylaxis to the subsequent application of SL-NH 2 to the same site. Notably, co-application of acid and SL-NH 2 following the initial injection of the pruritogen alone counteracted itch tachyphylaxis by augmenting the scratching behaviors in wild-type but not in acid-sensing ion channel 3-null, animals. Using an activity-dependent silencing strategy, we identified that acid-sensing ion channel 3-mediated itch enhancement mainly occurred via the Mas-related G-protein-coupled receptor C11-responsive sensory neurons. Together, our results indicate that acid-sensing ion channel 3, activated by concomitant acid and certain pruritogens, constitute a novel signaling pathway that counteracts itch tachyphylaxis to successive pruritogenic stimulation, which likely contributes to chronic itch associated with tissue acidosis.

Acidosis counteracts itch tachyphylaxis to consecutive pruritogen exposure dependent on acid-sensing ion channel 3

PubMed Central

Jiang, Yi-Ming; Huang, Chen; Peng, Zhong; Han, Shao-Ling; Li, Wei-Guang; Zhu, Michael Xi; Xu, Tian-Le

2017-01-01

Tachyphylaxis of itch refers to a markedly reduced scratching response to consecutive exposures of a pruritogen, a process thought to protect against tissue damage by incessant scratching and to become disrupted in chronic itch. Here, we report that a strong stimulation of the Mas-related G-protein-coupled receptor C11 by its agonist, Ser-Leu-Ile-Gly-Arg-Leu-NH2 (SL-NH2) or bovine adrenal medulla 8-22 peptide, via subcutaneous injection in mice induces tachyphylaxis to the subsequent application of SL-NH2 to the same site. Notably, co-application of acid and SL-NH2 following the initial injection of the pruritogen alone counteracted itch tachyphylaxis by augmenting the scratching behaviors in wild-type but not in acid-sensing ion channel 3-null, animals. Using an activity-dependent silencing strategy, we identified that acid-sensing ion channel 3-mediated itch enhancement mainly occurred via the Mas-related G-protein-coupled receptor C11-responsive sensory neurons. Together, our results indicate that acid-sensing ion channel 3, activated by concomitant acid and certain pruritogens, constitute a novel signaling pathway that counteracts itch tachyphylaxis to successive pruritogenic stimulation, which likely contributes to chronic itch associated with tissue acidosis. PMID:28745101

Effect of acid tolerance response (ATR) on attachment of Listeria monocytogenes Scott A to stainless steel under extended exposure to acid or/and salt stress and resistance of sessile cells to subsequent strong acid challenge.

PubMed

Chorianopoulos, Nikos; Giaouris, Efstathios; Grigoraki, Ioanna; Skandamis, Panagiotis; Nychas, George-John

2011-02-28

The aim of this study was to investigate the potential effect of adaptive stationary phase acid tolerance response (ATR) of Listeria monocytogenes Scott A cells on their attachment to stainless steel (SS) under low pH or/and high salt conditions and on the subsequent resistance of sessile cells to strong acid challenge. Nonadapted or acid-adapted stationary-phase L. monocytogenes cells were used to inoculate (ca. 10⁸ CFU/ml) Brain Heart (BH) broth (pH 7.4, 0.5% w/v NaCl) in test tubes containing vertically placed SS coupons (used as abiotic substrates for bacterial attachment). Incubation was carried out at 16 °C for up to 15 days, without any nutrient refreshment. L. monocytogenes cells, prepared as described above, were also exposed to low pH (4.5; adjusted with HCl) or/and high salt (5.5% w/v NaCl) stresses, during attachment. On the 5th, 10th and 15th day of incubation, cells attached to SS coupons were detached (through bead vortexing) and enumerated (by agar plating). Results revealed that ATR significantly (p<0.05) affected bacterial attachment, when the latter took place under moderate acidic conditions (pH 4.5, 0.5 or 5.5% w/v NaCl), with the acid-adapted cells adhering slightly more than the nonadapted ones. Regardless of acidity/salinity conditions during attachment, ATR also enhanced the resistance of sessile cells to subsequent lethal acid challenge (exposure to pH 2 for 6 min; pH adjusted with either hydrochloric or lactic acid). The trend observed with viable count data agreed well with conductance measurements, used to indirectly quantify remaining attached bacteria (following the strong acid challenge) via their metabolic activity. To sum, this study demonstrates that acid adaptation of L. monocytogenes cells during their planktonic growth enhances their subsequent attachment to SS under extended exposure (at 16 °C for up to 15 days) to mild acidic conditions (pH 4.5), while it also improves the resistance of sessile cells to extreme acid

Time series models of environmental exposures: Good predictions or good understanding.

PubMed

Barnett, Adrian G; Stephen, Dimity; Huang, Cunrui; Wolkewitz, Martin

2017-04-01

Time series data are popular in environmental epidemiology as they make use of the natural experiment of how changes in exposure over time might impact on disease. Many published time series papers have used parameter-heavy models that fully explained the second order patterns in disease to give residuals that have no short-term autocorrelation or seasonality. This is often achieved by including predictors of past disease counts (autoregression) or seasonal splines with many degrees of freedom. These approaches give great residuals, but add little to our understanding of cause and effect. We argue that modelling approaches should rely more on good epidemiology and less on statistical tests. This includes thinking about causal pathways, making potential confounders explicit, fitting a limited number of models, and not over-fitting at the cost of under-estimating the true association between exposure and disease. Copyright © 2017 Elsevier Inc. All rights reserved.

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.

Urinary trans,trans-muconic acid as an indicator of exposure to benzene in cigarette smokers.

PubMed

Melikian, A A; Prahalad, A K; Hoffmann, D

1993-01-01

Epidemiological studies have shown an association between cigarette smoking and increased risk of myeloid leukemia in smokers. In evaluating this link it is important to note that cigarette smoke contains benzene, among other carcinogens. Since chronic benzene, among other carcinogens. Since chronic benzene exposure causes acute myeloid leukemia in humans, we aimed to determine the uptake and metabolic activation of benzene from cigarette smoke in smokers by measuring the levels of the urinary benzene metabolite, trans,trans-muconic acid (t,t-MA). The method used involved a clean-up procedure, followed by high-performance liquid chromatography with UV detection. The levels of urinary t,t-MA ranged from 0.02 to 1.3 mg/g creatinine, resulting in a mean of 0.29 +/- 0.04 mg/g creatinine in 42 male smokers, and corresponding values in nonsmokers ranged from "nondetectable" to 0.52 mg/g creatinine with an average of 0.09 +/- 0.02 mg/g creatinine. In the current study, the levels of t,t-MA in smokers were about 3 times higher than those in nonsmokers (P = 0.0001), and a significant correlation between concentration of t,t-MA and levels of cotinine in smokers was observed (r = 0.55; P = 0.0001; 95% confidence interval, 0.30-0.93), suggesting that urinary t,t-MA can be utilized as a biochemical marker to quantitate benzene exposure due to cigarette smoking.

Lead exposure in US worksites: A literature review and development of an occupational lead exposure database from the published literature

PubMed Central

Koh, Dong-Hee; Locke, Sarah J.; Chen, Yu-Cheng; Purdue, Mark P.; Friesen, Melissa C.

2016-01-01

Background Retrospective exposure assessment of occupational lead exposure in population-based studies requires historical exposure information from many occupations and industries. Methods We reviewed published US exposure monitoring studies to identify lead exposure measurement data. We developed an occupational lead exposure database from the 175 identified papers containing 1,111 sets of lead concentration summary statistics (21% area air, 47% personal air, 32% blood). We also extracted ancillary exposure-related information, including job, industry, task/location, year collected, sampling strategy, control measures in place, and sampling and analytical methods. Results Measurements were published between 1940 and 2010 and represented 27 2-digit standardized industry classification codes. The majority of the measurements were related to lead-based paint work, joining or cutting metal using heat, primary and secondary metal manufacturing, and lead acid battery manufacturing. Conclusions This database can be used in future statistical analyses to characterize differences in lead exposure across time, jobs, and industries. PMID:25968240

Improvement of human cell line activation test (h-CLAT) using short-time exposure methods for prevention of false-negative results.

PubMed

Narita, Kazuto; Ishii, Yuuki; Vo, Phuc Thi Hong; Nakagawa, Fumiko; Ogata, Shinichi; Yamashita, Kunihiko; Kojima, Hajime; Itagaki, Hiroshi

2018-01-01

Recently, animal testing has been affected by increasing ethical, social, and political concerns regarding animal welfare. Several in vitro safety tests for evaluating skin sensitization, such as the human cell line activation test (h-CLAT), have been proposed. However, similar to other tests, the h-CLAT has produced false-negative results, including in tests for acid anhydride and water-insoluble chemicals. In a previous study, we demonstrated that the cause of false-negative results from phthalic anhydride was hydrolysis by an aqueous vehicle, with IL-8 release from THP-1 cells, and that short-time exposure to liquid paraffin (LP) dispersion medium could reduce false-negative results from acid anhydrides. In the present study, we modified the h-CLAT by applying this exposure method. We found that the modified h-CLAT is a promising method for reducing false-negative results obtained from acid anhydrides and chemicals with octanol-water partition coefficients (LogK ow ) greater than 3.5. Based on the outcomes from the present study, a combination of the original and the modified h-CLAT is suggested for reducing false-negative results. Notably, the combination method provided a sensitivity of 95% (overall chemicals) or 93% (chemicals with LogK ow > 2.0), and an accuracy of 88% (overall chemicals) or 81% (chemicals with LogK ow > 2.0). We found that the combined method is a promising evaluation scheme for reducing false-negative results seen in existing in vitro skin-sensitization tests. In the future, we expect a combination of original and modified h-CLAT to be applied in a newly developed in vitro test for evaluating skin sensitization.

CR@BaSO4: an acid rain-indicating material.

PubMed

Gao, Hong-Wen; Xu, Xin-Hui

2011-12-28

The CR@BaSO(4) hybrid was synthesized, characterized and used as an acid rain-indicating (ARI) material. A painted ARI umbrella was discolored after exposure to simulated acid rain of pH 5 or less and returned to the initial color after the rain stopped. Such a functionalized material may make acid rain visual to remind people in real-time. This journal is © The Royal Society of Chemistry 2011

Novel Bioluminescent Quantitative Detection of Nucleic Acid Amplification in Real-Time

PubMed Central

Gandelman, Olga A.; Church, Vicki L.; Moore, Cathy A.; Kiddle, Guy; Carne, Christopher A.; Parmar, Surendra; Jalal, Hamid; Tisi, Laurence C.; Murray, James A. H.

2010-01-01

Background The real-time monitoring of polynucleotide amplification is at the core of most molecular assays. This conventionally relies on fluorescent detection of the amplicon produced, requiring complex and costly hardware, often restricting it to specialised laboratories. Principal Findings Here we report the first real-time, closed-tube luminescent reporter system for nucleic acid amplification technologies (NAATs) enabling the progress of amplification to be continuously monitored using simple light measuring equipment. The Bioluminescent Assay in Real-Time (BART) continuously reports through bioluminescent output the exponential increase of inorganic pyrophosphate (PPi) produced during the isothermal amplification of a specific nucleic acid target. BART relies on the coupled conversion of inorganic pyrophosphate (PPi) produced stoichiometrically during nucleic acid synthesis to ATP by the enzyme ATP sulfurylase, and can therefore be coupled to a wide range of isothermal NAATs. During nucleic acid amplification, enzymatic conversion of PPi released during DNA synthesis into ATP is continuously monitored through the bioluminescence generated by thermostable firefly luciferase. The assay shows a unique kinetic signature for nucleic acid amplifications with a readily identifiable light output peak, whose timing is proportional to the concentration of original target nucleic acid. This allows qualitative and quantitative analysis of specific targets, and readily differentiates between negative and positive samples. Since quantitation in BART is based on determination of time-to-peak rather than absolute intensity of light emission, complex or highly sensitive light detectors are not required. Conclusions The combined chemistries of the BART reporter and amplification require only a constant temperature maintained by a heating block and are shown to be robust in the analysis of clinical samples. Since monitoring the BART reaction requires only a simple light

Stillbirth risk factors according to timing of exposure.

PubMed

Dodds, Linda; King, Will D; Fell, Deshayne B; Armson, B Anthony; Allen, Alexander; Nimrod, Carl

2006-08-01

The purpose of the present study is to identify risk factors for stillbirth and explore hypotheses about the cause of stillbirth based on the time in gestation when exposures occur. Relationships between lifestyle factors, pregnancy conditions, medication use, and occupation on risk for stillbirth were examined within a population-based case-control study. Women who had a stillbirth and a random sample of women who had a live birth between 1999 and 2001 were identified through perinatal databases in Nova Scotia and Eastern Ontario, Canada. Exposure data were collected for each month of pregnancy and analyzed within trimesters. Case-control data were converted to case-cohort data, and hazard ratios (HRs) and 95% confidence intervals (CIs) were determined from Cox proportional hazards models. This study included 105 stillbirth cases and 389 live-birth controls. Fertility treatment in the present pregnancy was associated with increased risk for stillbirth (adjusted HR, 4.0; 95% CI, 1.4-11.6). Smoking during the first trimester also was associated with increased risk for stillbirth (adjusted HR, 2.4; 95% CI, 1.2-4.9). Other risk factors included antiemetic use during the first trimester, second-trimester antibiotic use, low family income, and age older than 35 years. Risk factors identified in this study concur with findings of previous studies and support the importance of early pregnancy exposures on stillbirth risk.

Potential human health effects of acid rain: report of a workshop

PubMed Central

Goyer, Robert A.; Bachmann, John; Clarkson, Thomas W.; Ferris, Benjamin G.; Graham, Judith; Mushak, Paul; Perl, Daniel P.; Rall, David P.; Schlesinger, Richard; Sharpe, William; Wood, John M.

1985-01-01

This report summarizes the potential impact of the acid precipitation phenomenon on human health. There are two major components to this phenomenon: the predepositional phase, during which there is direct human exposure to acidic substances from ambient air, and the post-depositional phase, in which the deposition of acid materials on water and soil results in the mobilization, transport, and even chemical transformation of toxic metals. Acidification increases bioconversion of mercury to methylmercury, which accumulates in fish, increasing the risk to toxicity in people who eat fish. Increase in water and soil content of lead and cadmium increases human exposure to these metals which become additive to other sources presently under regulatory control. The potential adverse health effects of increased human exposure to aluminum is not known at the present time. PMID:3896772

Sampling and analysis of hexavalent chromium during exposure to chromic acid mist and welding fumes.

PubMed

Blomquist, G; Nilsson, C A; Nygren, O

1983-12-01

Sampling and analysis of hexavalent chromium during exposure to chromic acid mist and welding fumes. Scand j work environ & health 9 (1983) 489-495. In view of the serious health effects of hexavalent chromium, the problems involved in its sampling and analysis in workroom air have been the subject of much concern. In this paper, the stability problems arising from the reduction of hexavalent to trivalent chromium during sampling, sample storage, and analysis are discussed. Replacement of sulfuric acid by a sodium acetate buffer (pH 4) as a leaching solution prior to analysis with the diphenylcarbazide (DPC) method is suggested and is demonstrated to be necessary in order to avoid reduction. Field samples were taken from two different industrial processes-manual metal arc welding on stainless steel without shield gas and chromium plating. A comparison was made of the DPC method, acidic dissolution with atomic absorption spectrophotometric (AAS) analysis, and the carbonate method. For chromic acid mist, the DPC method and AAS analysis were shown to give the same results. In the analysis of welding fumes, the modified DPC method gave the same results as the laborious and less sensitive carbonate method.

Changes on lipid peroxidation,enzymatic activities and gene expression in planarian (Dugesia japonica) following exposure to perfluorooctanoic acid.

PubMed

Yuan, Zuoqing; Miao, Zili; Gong, Xiaoning; Zhao, Baoying; Zhang, Yuanyuan; Ma, Hongdou; Zhang, Jianyong; Zhao, Bosheng

2017-11-01

We investigated perfluorooctanoic acid (PFOA)-induced stress response in planarians. We administered different concentrations of PFOA to planarians for up to 10 d. PFOA exposure resulted in significant concentration-dependent elevations in lipid peroxidation, glutathione S-transferase and caspase-3 protease activities, and a significant decline in glutathione peroxidase activities compared with control groups. Exposure to PFOA significantly up-regulated the heat shock proteins hsp70 and hsp90, and p53, and down-regulated hsp40 compared with controls. PFOA exposure also increased HSP70 protein levels, as demonstrated by western blot analysis. These alterations indicated that PFOA exposure induced a stress response and affected the regulation of oxidative stress, enzymatic activities and gene expression. These results suggest that these sensitive parameters, together with other biomarkers, could be used for evaluating toxicity, for ecological risk assessment of PFOA in freshwaters. Copyright © 2017 Elsevier Inc. All rights reserved.

Evaluation of sampling methods for measuring exposure to volatile inorganic acids in workplace air. Part 1: sampling hydrochloric acid (HCl) and nitric acid (HNO₃) from a test gas atmosphere.

PubMed

Howe, Alan; Musgrove, Darren; Breuer, Dietmar; Gusbeth, Krista; Moritz, Andreas; Demange, Martine; Oury, Véronique; Rousset, Davy; Dorotte, Michel

2011-08-01

Historically, workplace exposure to the volatile inorganic acids hydrochloric acid (HCl) and nitric acid (HNO(3)) has been determined mostly by collection on silica gel sorbent tubes and analysis of the corresponding anions by ion chromatography (IC). However, HCl and HNO(3) can be present in workplace air in the form of mist as well as vapor, so it is important to sample the inhalable fraction of airborne particles. As sorbent tubes exhibit a low sampling efficiency for inhalable particles, a more suitable method was required. This is the first of two articles on "Evaluation of Sampling Methods for Measuring Exposure to Volatile Inorganic Acids in Workplace Air" and describes collaborative sampling exercises carried out to evaluate an alternative method for sampling HCl and HNO(3) using sodium carbonate-impregnated filters. The second article describes sampling capacity and breakthrough tests. The method was found to perform well and a quartz fiber filter impregnated with 500 μL of 1 M Na(2)CO(3) (10% (m/v) Na(2)CO(3)) was found to have sufficient sampling capacity for use in workplace air measurement. A pre-filter is required to remove particulate chlorides and nitrates that when present would otherwise result in a positive interference. A GSP sampler fitted with a plastic cone, a closed face cassette, or a plastic IOM sampler were all found to be suitable for mounting the pre-filter and sampling filter(s), but care has to be taken with the IOM sampler to ensure that the sampler is tightly closed to avoid leaks. HCl and HNO(3) can react with co-sampled particulate matter on the pre-filter, e.g., zinc oxide, leading to low results, and stronger acids can react with particulate chlorides and nitrates removed by the pre-filter to liberate HCl and HNO(3), which are subsequently collected on the sampling filter, leading to high results. However, although there is this potential for both positive and negative interferences in the measurement, these are unavoidable

Longitudinal Mediation Analysis with Time-varying Mediators and Exposures, with Application to Survival Outcomes

PubMed Central

Zheng, Wenjing; van der Laan, Mark

2017-01-01

In this paper, we study the effect of a time-varying exposure mediated by a time-varying intermediate variable. We consider general longitudinal settings, including survival outcomes. At a given time point, the exposure and mediator of interest are influenced by past covariates, mediators and exposures, and affect future covariates, mediators and exposures. Right censoring, if present, occurs in response to past history. To address the challenges in mediation analysis that are unique to these settings, we propose a formulation in terms of random interventions based on conditional distributions for the mediator. This formulation, in particular, allows for well-defined natural direct and indirect effects in the survival setting, and natural decomposition of the standard total effect. Upon establishing identifiability and the corresponding statistical estimands, we derive the efficient influence curves and establish their robustness properties. Applying Targeted Maximum Likelihood Estimation, we use these efficient influence curves to construct multiply robust and efficient estimators. We also present an inverse probability weighted estimator and a nested non-targeted substitution estimator for these parameters. PMID:29387520

Relationship between hand-arm vibration exposure and onset time for symptoms in a heavy engineering production workshop.

PubMed

Burström, Lage; Hagberg, Mats; Lundström, Ronnie; Nilsson, Tohr

2006-06-01

This study examined onset time for reported vascular and neurological symptoms in relation to the vibration load in a group of workers exposed to vibration. Information on the self-stated year for the first occurrence of symptoms was collected by means of questionnaires. During interviews data were obtained on self-stated estimations of daily exposure time, type of tool, and number of months or years with different exposures. The estimations of the vibration magnitudes of exposure were based on conducted measurements. From these data, the individual vibration exposure at the time of onset of symptoms was calculated. The incidence was 25.6 and 32.9 per 1000 exposure years for vascular and neurological symptoms, respectively, in the group of workers. The first onset of symptoms appeared after an average of 12 years of exposure. For the workers, the symptoms of vascular or neurological disorders started after about the same number of exposure years. The calculated accumulated acceleration correlated best with the onset time of symptoms. It was concluded that, since the workers' exposure to vibration was below the action level established in the European vibration directive, the results suggest that the action level is not a safe level for avoiding vascular and neurological symptoms.

Radiation exposure in transcatheter patent ductus arteriosus closure: time to tune?

PubMed

Villemain, Olivier; Malekzadeh-Milani, Sophie; Sitefane, Fidelio; Mostefa-Kara, Meriem; Boudjemline, Younes

2018-05-01

The aims of this study were to describe radiation level at our institution during transcatheter patent ductus arteriosus occlusion and to evaluate the components contributing to radiation exposure. Transcatheter occlusion relying on X-ray imaging has become the treatment of choice for patients with patent ductus arteriosus. Interventionists now work hard to minimise radiation exposure in order to reduce risk of induced cancers. We retrospectively reviewed all consecutive children who underwent transcatheter closure of patent ductus arteriosus from January 2012 to January 2016. Clinical data, anatomical characteristics, and catheterisation procedure parameters were reported. Radiation doses were analysed for the following variables: total air kerma, mGy; dose area product, Gy.cm2; dose area product per body weight, Gy.cm2/kg; and total fluoroscopic time. A total of 324 patients were included (median age=1.51 [Q1-Q3: 0.62-4.23] years; weight=10.3 [6.7-17.0] kg). In all, 322/324 (99.4%) procedures were successful. The median radiation doses were as follows: total air kerma: 26 (14.5-49.3) mGy; dose area product: 1.01 (0.56-2.24) Gy.cm2; dose area product/kg: 0.106 (0.061-0.185) Gy.cm2/kg; and fluoroscopic time: 2.8 (2-4) min. In multivariate analysis, a weight >10 kg, a ductus arteriosus width <2 mm, complications during the procedure, and a high frame rate (15 frames/second) were risk factors for an increased exposure. Lower doses of radiation can be achieved with subsequent recommendations: technical improvement, frame rate reduction, avoidance of biplane cineangiograms, use of stored fluoroscopy as much as possible, and limitation of fluoroscopic time. A greater use of echocardiography might even lessen the exposure.

Exposure to acute severe hypoxia leads to increased urea loss and disruptions in acid-base and ionoregulatory balance in dogfish sharks (Squalus acanthias).

PubMed

Zimmer, Alex M; Wood, Chris M

2014-01-01

The effects of acute moderate (20% air O2 saturation; 6-h exposure) and severe (5% air O2 saturation; 4-h exposure) hypoxia on N-waste, acid-base, and ion balance in dogfish sharks (Squalus acanthias suckleyi) were evaluated. We predicted that the synthesis and/or retention of urea, which are active processes, would be inhibited by hypoxia. Exposure to moderate hypoxia had negligible effects on N-waste fluxes or systemic physiology, except for a modest rise in plasma lactate. Exposure to severe hypoxia led to a significant increase in urea excretion (Jurea), while plasma, liver, and muscle urea concentrations were unchanged, suggesting a loss of urea retention. Ammonia excretion (Jamm) was elevated during normoxic recovery. Moreover, severe hypoxia led to disruptions in acid-base balance, indicated by a large increase in plasma [lactate] and substantial decreases in arterial pHa and plasma [Formula: see text], as well as loss of ionic homeostasis, indicated by increases in plasma [Mg(2+)], [Ca(2+)], and [Na(+)]. We suggest that severe hypoxia in dogfish sharks leads to a reduction in active gill homeostatic processes, such as urea retention, acid-base regulation and ionoregulation, and/or an osmoregulatory compromise due to increased functional gill surface area. Overall, the results provide a comprehensive picture of the physiological responses to a severe degree of hypoxia in an ancient fish species.

DPOAEs in infants developmentally exposed to PCBs show two differently time spaced exposure sensitive windows.

PubMed

Koštiaková, Vladimíra; Moleti, Arturo; Wimmerová, Soňa; Jusko, Todd A; Palkovičová Murínová, Ľubica; Sisto, Renata; Richterová, Denisa; Kováč, Ján; Čonka, Kamil; Patayová, Henrieta; Tihányi, Juraj; Trnovec, Tomáš

2016-10-01

The study aim was to identify the timing of sensitive windows for ototoxicity related to perinatal exposure to PCBs. A total of 351 and 214 children from a birth cohort in eastern Slovakia underwent otoacoustic testing at 45 and 72 months, respectively, and distortion product otoacoustic emissions (DPOAEs) at 11 frequencies were recorded. Cord and child 6-, 16-, 45-, and 72- month blood samples were analyzed for PCB 153 concentration. The PCB 153 concentration-time profiles were approximated with a system model to calculate area under the PCB*time curves (AUCs) for specific time intervals (3 and 6 months for 45 and 72 months data, respectively). DPOAE amplitudes were correlated (Spearman) with cord serum PCB and AUCs, markers of prenatal and postnatal exposure, respectively. Two exposure critical windows were identified in infants, the first related to prenatal and early postnatal and the second to postnatal exposure to PCBs. Our data have shown tonotopicity, sexual dimorphism, and asymmetry in ototoxicity of PCBs. Copyright © 2016. Published by Elsevier Ltd.

Mendelian randomization analysis of a time-varying exposure for binary disease outcomes using functional data analysis methods.

PubMed

Cao, Ying; Rajan, Suja S; Wei, Peng

2016-12-01

A Mendelian randomization (MR) analysis is performed to analyze the causal effect of an exposure variable on a disease outcome in observational studies, by using genetic variants that affect the disease outcome only through the exposure variable. This method has recently gained popularity among epidemiologists given the success of genetic association studies. Many exposure variables of interest in epidemiological studies are time varying, for example, body mass index (BMI). Although longitudinal data have been collected in many cohort studies, current MR studies only use one measurement of a time-varying exposure variable, which cannot adequately capture the long-term time-varying information. We propose using the functional principal component analysis method to recover the underlying individual trajectory of the time-varying exposure from the sparsely and irregularly observed longitudinal data, and then conduct MR analysis using the recovered curves. We further propose two MR analysis methods. The first assumes a cumulative effect of the time-varying exposure variable on the disease risk, while the second assumes a time-varying genetic effect and employs functional regression models. We focus on statistical testing for a causal effect. Our simulation studies mimicking the real data show that the proposed functional data analysis based methods incorporating longitudinal data have substantial power gains compared to standard MR analysis using only one measurement. We used the Framingham Heart Study data to demonstrate the promising performance of the new methods as well as inconsistent results produced by the standard MR analysis that relies on a single measurement of the exposure at some arbitrary time point. © 2016 WILEY PERIODICALS, INC.

Extinction of Contextual Fear with Timed Exposure to Enriched Environment: A Differential Effect

PubMed Central

Hegde, Preethi; O'Mara, Shane; Laxmi, Thenkanidiyoor Rao

2017-01-01

Background Extinction of fear memory depends on the environmental and emotional cues. Furthermore, consolidation of extinction is also dependent on the environmental exposure. But, the relationship of the time of the exposure to a variety of environmental cues is not well known. The important region involved in facilitation of extinction of fear memory is through diversion of the flow of information leaving the lateral nucleus of amygdala. Purpose The study aimed to address a question to explain how these brain regions react to environmental stimulation during the retention and extinction of fear memory. Methods An enriched environment (EE) is assumed to mediate extinction of fear memory, we examined the apparent discrepancy between the effects of defensive response, the freezing behavior induced by Pavlovian classical fear conditioning by subjecting them to variance in the timing to EE. The different timing of EE exposure was 10 days of EE either before fear conditioning and/or after extinction training to the rats. The local field potentials was recorded from CA1 hippocampus, lateral nucleus of amygdala and infralimbic region of medial prefrontal cortex (mPFC) during the fear learning and extinction from the control rats and rats exposed to EE before and after fear conditioning. Results Exposure to EE before the fear conditioning and after extinction training was more effective in the extinction fear memory. In addition, we also found switching from exploratory locomotion to freezing during retention of contextual fear memory which was associated with decreased theta power and reduced synchronized theta oscillations in CA1-hippocampus, lateral nucleus of amygdala, and infralimbic region of mPFC. Conclusion Thus, we propose that the timing of exposure to EE play a key role in the extinction of fear memory. PMID:28588364

Correlation of IMPDH1 gene polymorphisms with subclinical acute rejection and mycophenolic acid exposure parameters on day 28 after renal transplantation.

PubMed

Kagaya, Hideaki; Miura, Masatomo; Saito, Mitsuru; Habuchi, Tomonori; Satoh, Shigeru

2010-08-01

The risk of acute rejection in patients with higher exposure to mycophenolic acid (MPA), the active metabolite of mycophenolate mofetil (MMF), might be due to inosine 5'-monophosphate dehydrogenase (IMPDH) polymorphisms. The correlations with subclinical acute rejection, IMPDH1 polymorphisms and MPA exposure on day 28 post-transplantation were investigated in 82 Japanese recipients. Renal transplant recipients were given combination immunosuppressive therapy consisting of tacrolimus and 1.0, 1.5 or 2.0 g/day of MMF in equally divided doses every 12 hr at designated times. There were no significant differences in the incidence of subclinical acute rejection between IMPDH1 rs2278293 or rs2278294 polymorphisms (p = 0.243 and 0.735, respectively). However, in the high MPA night-time exposure range (AUC > 60 microg x h/ml and C(0 )> or = 1.9 microg/ml), there was a significant difference in the incidence of subclinical acute rejection between IMPDH1 rs2278293 A/A, A/G and G/G genotypes (each p = 0.019), but not the IMPDH1 rs2278294 genotype. In the higher daytime MPA exposure range, patients with the IMPDH1 rs2278293 G/G genotype also tended to develop subclinical acute rejection. In patients with the IMPDH rs2278293 A/A genotype, the risk of subclinical acute rejection episode tends to be low and the administration of MMF was effective. The risk of subclinical acute rejection for recipients who cannot adapt in therapeutic drug monitoring (TDM) of MPA seems to be influenced by IMPDH1 rs2278293 polymorphism. The prospective analysis of IMPDH1 rs2278293 polymorphism as well as monitoring of MPA plasma concentration after transplantation might help to improve MMF therapy.

Trends in Occupational Exposure to Styrene in the European Glass Fibre-Reinforced Plastics Industry

PubMed Central

Van Rooij, J. G. M.; Kasper, A.; Triebig, G.; Werner, P.; Kromhout, H.

2008-01-01

Aim: This study presents temporal trends of styrene exposure for workers in the European glass fibre-reinforced plastics (GRP) industry during the period 1966–2002. Methods: Data of personal styrene exposure measurements were retrieved from reports, databases and peer-reviewed papers. Only sources with descriptive statistics of personal measurements were accepted. The styrene exposure data cover personal air samples and biological monitoring data, that is, urinary styrene metabolites (mandelic acid and/or phenylglyoxylic acid) and styrene in blood. Means of series of measurements were categorized by year, country, production process, job and sampling strategy. Linear mixed models were used to identify temporal trends and factors affecting exposure levels. Results: Personal exposure measurements were available from 60 reports providing data on 24145 1–8-h time-weighted average shift personal air samples. Available data of biological exposure indicators included measurements of mandelic acid in post-shift urine (6361 urine samples being analysed). Trend analyses of the available styrene exposure data showed that the average styrene concentration in the breathing zone of open-mould workers in the European GRP industry has decreased on average by 5.3% per year during the period 1966–1990 and by only 0.4% annually in the period after 1990. The highest exposures were measured in Southern Europe and the lowest exposures in Northern Europe with Central Europe in between. Biological indicators of styrene (mandelic acid in post-shift urine) showed a somewhat steeper decline (8.9%), most likely because urine samples were collected in companies that showed a stronger decrease of styrene exposure in air than GRP companies where no biological measurements were carried out. PMID:18550625

Physiological effects and tissue residues from exposure of leopard frogs to commercial naphthenic acids.

PubMed

Smits, Judit E G; Hersikorn, Blair D; Young, Rozlyn F; Fedorak, Phillip M

2012-10-15

Naphthenic acids (NAs) have been cited as one of the main causes of the toxicity related to oil sands process-affected materials and have recently been measured in biological tissues (fish). However, adverse effects have not been a consistent finding in toxicology studies on vertebrates. This study set out to determine two factors: 1) whether exposure to commercial NAs (Refined Merichem) resulted in detectable tissue residues in native amphibians (northern leopard frogs, Lithobates pipiens), and 2) whether such exposure would produce clinical or subclinical toxicity. Frogs were kept in NA solutions (0, 20, or 40 mg/L) under saline conditions comparable to that on reclaimed wetlands in the Athabasca oil sands for 28 days. These exposures resulted in proportional NA concentrations in muscle tissue of the frogs, estimated by gas chromatography-mass spectrometry analyses. Detailed studies determined if the increasing concentrations of NAs, and subsequently increased tissue NA levels, caused a proportional compromise in the health of the experimental animals. Physiological investigations included innate immune function, thyroid hormone levels, and hepatic detoxification enzyme induction, none of which differed in response to increased exposures or tissue concentrations of NAs. Body mass did increase in both the salt- and NA-exposed animals, likely related to osmotic pressure and uptake of water through the skin. Our results demonstrate that commercial NAs are absorbed and deposited in muscle tissue, yet they show few negative physiological or toxicological effects on the frogs. Copyright © 2012. Published by Elsevier B.V.

Human short-term exposure to electromagnetic fields emitted by mobile phones decreases computer-assisted visual reaction time.

PubMed

Mortazavi, S M J; Rouintan, M S; Taeb, S; Dehghan, N; Ghaffarpanah, A A; Sadeghi, Z; Ghafouri, F

2012-06-01

The worldwide dramatic increase in mobile phone use has generated great concerns about the detrimental effects of microwave radiations emitted by these communication devices. Reaction time plays a critical role in performing tasks necessary to avoid hazards. As far as we know, this study is the first survey that reports decreased reaction time after exposure to electromagnetic fields generated by a high specific absorption rate mobile phone. It is also the first study in which previous history of mobile phone use is taken into account. The aim of this study was to assess both the acute and chronic effects of electromagnetic fields emitted by mobile phones on reaction time in university students. Visual reaction time (VRT) of young university students was recorded with a simple blind computer-assisted-VRT test, before and after a 10 min real/sham exposure to electromagnetic fields of mobile phones. Participants were 160 right-handed university students aged 18-31. To assess the effect of chronic exposures, the reaction time in sham-exposed phases were compared among low level, moderate and frequent users of mobile phones. The mean ± SD reaction time after real exposure and sham exposure were 286.78 ± 31.35 ms and 295.86 ± 32.17 ms (P < 0.001), respectively. The age of students did not significantly alter the reaction time either in talk or in standby mode. The reaction time either in talk or in standby mode was shorter in male students. The students' VRT was significantly affected by exposure to electromagnetic fields emitted by a mobile phone. It can be concluded that these exposures cause decreased reaction time, which may lead to a better response to different hazards. In this light, this phenomenon might decrease the chances of human errors and fatal accidents.

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...

Effect of air breathing on acid-base and ion regulation after exhaustive exercise and during low pH exposure in the bowfin, Amia calva.

PubMed

Gonzalez, R J; Milligan, L; Pagnotta, A; McDonald, D G

2001-01-01

To explore a potential conflict between air breathing and acid-base regulation in the bowfin (Amia calva), we examined how individuals with access to air differed from fish without air access in their response to acidosis. After exhaustive exercise, bowfin with access to air recovered significantly more slowly from the acidosis than fish without air access. While arterial blood pH (pH(a)) of fish without air access recovered to resting levels by 8 h, pH(a) was still significantly depressed in fish having access to air. In addition, Pco(2) was slightly more elevated in fish having air access than those without it. Fish with access to air still had a significant metabolic acid load after 8-h recovery, while those without air access completely cleared the load within 4 h. These results suggest that bowfin with access to air were breathing air and, consequently, were less able to excrete CO(2) and H(+) and experienced a delayed recovery. In contrast, during exposure to low pH, air breathing seemed to have a protective effect on acid-base status in bowfin. During exposure to low pH water, bowfin with access to air developed a much milder acidosis than bowfin without air access. The more severe acidosis in fish without air access was caused by an increased rate of lactic acid production. It appears that enhanced O(2) delivery allowed air-breathing bowfin to avoid acidosis-induced anaerobic metabolism and lactic acid production. In addition, during low pH exposure, plasma Na(+) and Cl(-) concentrations of fish without air access fell slightly more rapidly than those in fish with air access, indicating that the branchial ventilatory changes associated with air breathing limited, to some degree, ion losses associated with low pH exposure.

Prenatal Ethanol Exposure Causes Glucose Intolerance with Increased Hepatic Gluconeogenesis and Histone Deacetylases in Adult Rat Offspring: Reversal by Tauroursodeoxycholic Acid

PubMed Central

Yao, Xing-Hai; Nguyen, Hoa K.; Nyomba, B. L. Grégoire

2013-01-01

Prenatal ethanol exposure results in increased glucose production in adult rat offspring and this may involve modulation of protein acetylation by cellular stress. We used adult male offspring of dams given ethanol during gestation days 1–7 (early), 8–14 (mid) and 15–21 (late) compared with those from control dams. A group of ethanol offspring was treated with tauroursodeoxycholic acid (TUDCA) for 3 weeks. We determined gluconeogenesis, phosphoenolpyruvate carboxykinase (PEPCK), glucose-6-phosphatase, hepatic free radicals, histone deacetylases (HDAC), acetylated foxo1, acetylated PEPCK, and C/EBP homologous protein as a marker of endoplasmic reticulum stress. Prenatal ethanol during either of the 3 weeks of pregnancy increased gluconeogenesis, gluconeogenic genes, oxidative and endoplasmic reticulum stresses, sirtuin-2 and HDAC3, 4, 5, and 7 in adult offspring. Conversely, prenatal ethanol reduced acetylation of foxo1 and PEPCK. Treatment of adult ethanol offspring with TUDCA reversed all these abnormalities. Thus, prenatal exposure of rats to ethanol results in long lasting oxidative and endoplasmic reticulum stresses explaining increased expression of gluconeogenic genes and HDAC proteins which, by deacetylating foxo1 and PEPCK, contribute to increased gluconeogenesis. These anomalies occurred regardless of the time of ethanol exposure during pregnancy, including early embryogenesis. As these anomalies were reversed by treatment of the adult offspring with TUDCA, this compound has therapeutic potentials in the treatment of glucose intolerance associated with prenatal ethanol exposure. PMID:23544086

In utero exposure to valproic acid and autism--a current review of clinical and animal studies.

PubMed

Roullet, Florence I; Lai, Jonathan K Y; Foster, Jane A

2013-01-01

Valproic acid (VPA) is both an anti-convulsant and a mood stabilizer. Clinical studies over the past 40 years have shown that exposure to VPA in utero is associated with birth defects, cognitive deficits, and increased risk of autism. Two recent FDA warnings related to use of VPA in pregnancy emphasize the need to reevaluate its use clinically during child-bearing years. The emerging clinical evidence showing a link between VPA exposure and both cognitive function and risk of autism brings to the forefront the importance of understanding how VPA exposure influences neurodevelopment. In the past 10 years, animal studies have investigated anatomical, behavioral, molecular, and physiological outcomes related to in utero VPA exposure. Behavioral studies show that VPA exposure in both rats and mice leads to autistic-like behaviors in the offspring, including social behavior deficits, increased repetitive behaviors, and deficits in communication. Based on this work VPA maternal challenge in rodents has been proposed as an animal model to study autism. This model has both face and construct validity; however, like all animal models there are limitations to its translation to the clinical setting. Here we provide a review of clinical studies that examined pregnancy outcomes of VPA use as well as the related animal studies. Copyright © 2013 Elsevier Inc. All rights reserved.

Intergenerational impact of paternal lifetime exposures to both folic acid deficiency and supplementation on reproductive outcomes and imprinted gene methylation.

PubMed

Ly, Lundi; Chan, Donovan; Aarabi, Mahmoud; Landry, Mylène; Behan, Nathalie A; MacFarlane, Amanda J; Trasler, Jacquetta

2017-07-01

Do paternal exposures to folic acid deficient (FD), and/or folic acid supplemented (FS) diets, throughout germ cell development adversely affect male germ cells and consequently offspring health outcomes? Male mice exposed over their lifetimes to both FD and FS diets showed decreased sperm counts and altered imprinted gene methylation with evidence of transmission of adverse effects to the offspring, including increased postnatal-preweaning mortality and variability in imprinted gene methylation. There is increasing evidence that disruptions in male germ cell epigenetic reprogramming are associated with offspring abnormalities and intergenerational disease. The fetal period is the critical time of DNA methylation pattern acquisition for developing male germ cells and an adequate supply of methyl donors is required. In addition, DNA methylation patterns continue to be remodeled during postnatal spermatogenesis. Previous studies have shown that lifetime (prenatal and postnatal) folic acid deficiency can alter the sperm epigenome and increase the incidence of fetal morphological abnormalities. Female BALB/c mice (F0) were placed on one of four amino-acid defined diets for 4 weeks before pregnancy and throughout pregnancy and lactation: folic acid control (Ctrl; 2 mg/kg), 7-fold folic acid deficient (7FD; 0.3 mg/kg), 10-fold high FS (10FS, 20 mg/kg) or 20-fold high FS (20FS, 40 mg/kg) diets. F1 males were weaned to their respective prenatal diets to allow for diet exposure during all windows of germline epigenetic reprogramming: the erasure, re-establishment and maintenance phases. F0 females were mated with chow-fed males to produce F1 litters whose germ cells were exposed to the diets throughout embryonic development. F1 males were subsequently mated with chow-fed female mice. Two F2 litters, unexposed to the experimental diets, were generated from each F1 male; one litter was collected at embryonic day (E)18.5 and one delivered and followed postnatally. DNA

Mass spectrometry profiling reveals altered plasma levels of monohydroxy fatty acids and related lipids in healthy humans after controlled exposure to biodiesel exhaust.

PubMed

Gouveia-Figueira, Sandra; Karimpour, Masoumeh; Bosson, Jenny A; Blomberg, Anders; Unosson, Jon; Sehlstedt, Maria; Pourazar, Jamshid; Sandström, Thomas; Behndig, Annelie F; Nording, Malin L

2018-08-14

Experimental human exposure studies are an effective tool to study adverse health effects from acute inhalation of particulate matter and other constituents of air pollution. In this randomized and double-blinded crossover study, we investigated the systemic effect on bioactive lipid metabolite levels after controlled biodiesel exhaust exposure of healthy humans and compared it to filtered air at a separate exposure occasion. Eicosanoids and other oxylipins, as well as endocannabinoids and related lipids, were quantified in plasma from 14 healthy volunteers at baseline and at three subsequent time points (2, 6, and 24 h) after 1 h exposure sessions. Protocols based on liquid chromatography (LC) coupled to tandem mass spectrometry (MS/MS) methods were developed to detect temporal changes in circulating levels after biodiesel exhaust exposure. The exhaust was generated by a diesel engine fed with an undiluted rapeseed methyl ester fuel. Among the 51 analyzed lipid metabolites, PGF 2α , 9,10-DiHOME, 9-HODE, 5-HETE, 11-HETE, 12-HETE, and DEA displayed significant responsiveness to the biodiesel exhaust exposure as opposed to filtered air. Of these, 9-HODE and 5-HETE at 24 h survived the 10% false discovery rate cutoff (p < 0.003). Hence, the majority of the responsive lipid metabolites were monohydroxy fatty acids. We conclude that it is possible to detect alterations in circulating bioactive lipid metabolites in response to biodiesel exhaust exposure using LC-MS/MS, with emphasis on metabolites with inflammation related properties and implications on cardiovascular health and disease. These observations aid future investigations on air pollution effects, especially with regard to cardiovascular outcomes. Copyright © 2018 Elsevier B.V. All rights reserved.

Altered Bile Acid Metabolome in Patients with Nonalcoholic Steatohepatitis.

PubMed

Ferslew, Brian C; Xie, Guoxiang; Johnston, Curtis K; Su, Mingming; Stewart, Paul W; Jia, Wei; Brouwer, Kim L R; Barritt, A Sidney

2015-11-01

The prevalence of nonalcoholic fatty liver disease (NAFLD) and steatohepatitis (NASH) is increasing at an alarming rate. The role of bile acids in the development and progression of NAFLD to NASH and cirrhosis is poorly understood. This study aimed to quantify the bile acid metabolome in healthy subjects and patients with non-cirrhotic NASH under fasting conditions and after a standardized meal. Liquid chromatography tandem mass spectroscopy was used to quantify 30 serum and 16 urinary bile acids from 15 healthy volunteers and 7 patients with biopsy-confirmed NASH. Bile acid concentrations were measured at two fasting and four post-prandial time points following a high-fat meal to induce gallbladder contraction and bile acid reabsorption from the intestine. Patients with NASH had significantly higher total serum bile acid concentrations than healthy subjects under fasting conditions (2.2- to 2.4-fold increase in NASH; NASH 2595-3549 µM and healthy 1171-1458 µM) and at all post-prandial time points (1.7- to 2.2-fold increase in NASH; NASH 4444-5898 µM and healthy 2634-2829 µM). These changes were driven by increased taurine- and glycine-conjugated primary and secondary bile acids. Patients with NASH exhibited greater variability in their fasting and post-prandial bile acid profile. Results indicate that patients with NASH have higher fasting and post-prandial exposure to bile acids, including the more hydrophobic and cytotoxic secondary species. Increased bile acid exposure may be involved in liver injury and the pathogenesis of NAFLD and NASH.

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. Copyright © 2016 Elsevier Inc. All rights reserved.

BME Estimation of Residential Exposure to Ambient PM10 and Ozone at Multiple Time Scales

PubMed Central

Yu, Hwa-Lung; Chen, Jiu-Chiuan; Christakos, George; Jerrett, Michael

2009-01-01

Background Long-term human exposure to ambient pollutants can be an important contributing or etiologic factor of many chronic diseases. Spatiotemporal estimation (mapping) of long-term exposure at residential areas based on field observations recorded in the U.S. Environmental Protection Agency’s Air Quality System often suffer from missing data issues due to the scarce monitoring network across space and the inconsistent recording periods at different monitors. Objective We developed and compared two upscaling methods: UM1 (data aggregation followed by exposure estimation) and UM2 (exposure estimation followed by data aggregation) for the long-term PM10 (particulate matter with aerodynamic diameter ≤ 10 μm) and ozone exposure estimations and applied them in multiple time scales to estimate PM and ozone exposures for the residential areas of the Health Effects of Air Pollution on Lupus (HEAPL) study. Method We used Bayesian maximum entropy (BME) analysis for the two upscaling methods. We performed spatiotemporal cross-validations at multiple time scales by UM1 and UM2 to assess the estimation accuracy across space and time. Results Compared with the kriging method, the integration of soft information by the BME method can effectively increase the estimation accuracy for both pollutants. The spatiotemporal distributions of estimation errors from UM1 and UM2 were similar. The cross-validation results indicated that UM2 is generally better than UM1 in exposure estimations at multiple time scales in terms of predictive accuracy and lack of bias. For yearly PM10 estimations, both approaches have comparable performance, but the implementation of UM1 is associated with much lower computation burden. Conclusion BME-based upscaling methods UM1 and UM2 can assimilate core and site-specific knowledge bases of different formats for long-term exposure estimation. This study shows that UM1 can perform reasonably well when the aggregation process does not alter the

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

Effect of Hydrofluoric Acid Etching Time on Titanium Topography, Chemistry, Wettability, and Cell Adhesion

PubMed Central

Zahran, R.; Rosales Leal, J. I.; Rodríguez Valverde, M. A.; Cabrerizo Vílchez, M. A.

2016-01-01

Titanium implant surface etching has proven an effective method to enhance cell attachment. Despite the frequent use of hydrofluoric (HF) acid, many questions remain unresolved, including the optimal etching time and its effect on surface and biological properties. The objective of this study was to investigate the effect of HF acid etching time on Ti topography, surface chemistry, wettability, and cell adhesion. These data are useful to design improved acid treatment and obtain an improved cell response. The surface topography, chemistry, dynamic wetting, and cell adhesiveness of polished Ti surfaces were evaluated after treatment with HF acid solution for 0, 2; 3, 5, 7, or 10 min, revealing a time-dependent effect of HF acid on their topography, chemistry, and wetting. Roughness and wetting increased with longer etching time except at 10 min, when roughness increased but wetness decreased. Skewness became negative after etching and kurtosis tended to 3 with longer etching time. Highest cell adhesion was achieved after 5–7 min of etching time. Wetting and cell adhesion were reduced on the highly rough surfaces obtained after 10-min etching time. PMID:27824875

Timing of dietary acid intake and erosive tooth wear: A case-control study.

PubMed

O'Toole, Saoirse; Bernabé, Eduardo; Moazzez, Rebecca; Bartlett, David

2017-01-01

There is a lack of clinical data on the impact of timing of dietary acid intake and toothbrush abrasion when attempting to control erosive tooth wear progression. The aim of this study was to estimate the association of theoretical causative factors with erosive tooth wear to inform evidence-based guidelines. Using case-control study design, 300 participants with dietary erosive tooth wear and 300 age-matched controls were recruited from the restorative clinics of King's College London Dental Institute. A previously validated questionnaire was adapted to be interviewer-led and to assess frequency, timing and duration of dietary acid intake in addition to alternate drinking habits prior to swallowing. Timing of toothbrushing in relation to meals and dietary acid intake was investigated. Associations with erosive tooth wear were assessed in crude and adjusted logistic regression models. Fruit intake between meals (p<0.001), but not with meals (p=0.206), was associated with erosive tooth wear and contrasted with acidic drinks which maintained a strong association regardless of timing of intake (OR up to 11.84 [95% CI: 5.42-25.89], p<0.001). Prolonged fruit eating and alternate drinking habits prior to swallowing (OR 12.82 [95% CI: 5.85-28.08] and 10.34 [95% CI: 4.85-22.06] respectively) were as strongly associated with erosive tooth wear as three or greater daily acid intakes (OR 10.92 [95% CI: 4.40-27.10]). Toothbrushing within 10min of acid intake was not associated with erosive tooth wear following adjustments for dietary factors (OR 1.41 [95% CI: 0.82-2.42], p=0.215]). Significantly increased odds ratios were observed when acids were consumed between meals in this cohort of patients. Universal advice to delay brushing after meals may not be substantiated. Prevention should be focused on avoiding dietary acids between meals, eliminating habits which increase contact time with the acid and reducing daily intake of acidic drinks. Toothbrushing after meals was not

Time allocation shifts and pollutant exposure due to traffic congestion: an analysis using the national human activity pattern survey.

PubMed

Zhang, Kai; Batterman, Stuart A

2009-10-15

Traffic congestion increases air pollutant exposures of commuters and urban populations due to the increased time spent in traffic and the increased vehicular emissions that occur in congestion, especially "stop-and-go" traffic. Increased time in traffic also decreases time in other microenvironments, a trade-off that has not been considered in previous time activity pattern (TAP) analyses conducted for exposure assessment purposes. This research investigates changes in time allocations and exposures that result from traffic congestion. Time shifts were derived using data from the National Human Activity Pattern Survey (NHAPS), which was aggregated to nine microenvironments (six indoor locations, two outdoor locations and one transport location). After imputing missing values, handling outliers, and conducting other quality checks, these data were stratified by respondent age, employment status and period (weekday/weekend). Trade-offs or time-shift coefficients between time spent in vehicles and the eight other microenvironments were then estimated using robust regression. For children and retirees, congestion primarily reduced the time spent at home; for older children and working adults, congestion shifted the time spent at home as well as time in schools, public buildings, and other indoor environments. Changes in benzene and PM(2.5) exposure were estimated for the current average travel delay in the U.S. (9 min day(-1)) and other scenarios using the estimated time shifts coefficients, concentrations in key microenvironments derived from the literature, and a probabilistic analysis. Changes in exposures depended on the duration of the congestion and the pollutant. For example, a 30 min day(-1) travel delay was determined to account for 21+/-12% of current exposure to benzene and 14+/-8% of PM(2.5) exposure. The time allocation shifts and the dynamic approach to TAPs improve estimates of exposure impacts from congestion and other recurring events.

Drinking water disinfection by-products and time to pregnancy.

PubMed

MacLehose, Richard F; Savitz, David A; Herring, Amy H; Hartmann, Katherine E; Singer, Philip C; Weinberg, Howard S

2008-05-01

Laboratory evidence suggests tap water disinfection by-products (DBPs) could have an effect very early in pregnancy, typically before clinical detectability. Undetected early losses would be expected to increase the reported number of cycles to clinical pregnancy. We investigated the association between specific DBPs (trihalomethanes, haloacetic acids, brominated-trihalomethanes, brominated-haloacetic acids, total organic halides, and bromodichloromethane) and time to pregnancy among women who enrolled in a study of drinking water and reproductive outcomes. We quantified exposure to DBPs through concentrations in tap water, quantity ingested through drinking, quantity inhaled or absorbed while showering or bathing, and total integrated exposure. The effect of DBPs on time to pregnancy was estimated using a discrete time hazard model. Overall, we found no evidence of an increased time to pregnancy among women who were exposed to higher levels of DBPs. A modestly decreased time to pregnancy (ie, increased fecundability) was seen among those exposed to the highest level of ingested DBPs, but not for tap water concentration, the amount absorbed while showering or bathing, or the integrated exposure. Our findings extend those of a recently published study suggesting a lack of association between DBPs and pregnancy loss.

Developmental PCB Exposure Increases Audiogenic Seizures and Decreases Glutamic Acid Decarboxylase in the Inferior Colliculus

PubMed Central

Bandara, Suren B.; Eubig, Paul A.; Sadowski, Renee N.; Schantz, Susan L.

2016-01-01

Previously, we observed that developmental polychlorinated biphenyl (PCB) exposure resulted in an increase in audiogenic seizures (AGSs) in rats. However, the rats were exposed to loud noise in adulthood, and were not tested for AGS until after 1 year of age, either of which could have interacted with early PCB exposure to increase AGS susceptibility. This study assessed susceptibility to AGS in young adult rats following developmental PCB exposure alone (without loud noise exposure) and investigated whether there was a decrease in GABA inhibitory neurotransmission in the inferior colliculus (IC) that could potentially explain this effect. Female Long-Evans rats were dosed orally with 0 or 6 mg/kg/day of an environmentally relevant PCB mixture from 28 days prior to breeding until the pups were weaned at postnatal day 21. One male-female pair from each litter was retained for the AGS study whilst another was retained for Western blot analysis of glutamic acid decarboxylase (GAD) and GABAAα1 receptor in the IC, the site in the auditory midbrain where AGS are initiated. There was a significant increase in the number and severity of AGSs in the PCB groups, with females somewhat more affected than males. GAD65 was decreased but there was no change in GAD67 or GABAAα1 in the IC indicating decreased inhibitory regulation in the PCB group. These results confirm that developmental PCB exposure alone is sufficient to increase susceptibility to AGS, and provide the first evidence for a possible mechanism of action at the level of the IC. PMID:26543103

A differential impact of mycophenolic acid, prednisolone, and tacrolimus exposure on sCD30 levels in adult kidney transplant recipients.

PubMed

Barraclough, Katherine A; Staatz, Christine E; Johnson, David W; Gillis, David; Lee, Katie J; McWhinney, Brett C; Ungerer, Jacobus P J; Campbell, Scott B; Isbel, Nicole M

2013-04-01

Soluble CD30 (sCD30) has been associated with rejection and graft loss in kidney transplantation, leading to the suggestion that sCD30 might be a useful biomarker to adjust immunosuppressant medication dosing. However, there has been minimal study of the influence of individual immunosuppressive drugs on sCD30 levels. To evaluate the influence of mycophenolic acid (MPA), prednisolone, and tacrolimus exposure on sCD30 levels in adult kidney transplant recipients. The sCD30 levels were measured pretransplant and 30 days posttransplant. Area under the concentration-time curve (AUC) for each drug was estimated on day 30 using validated, multiple regression-derived limited sampling strategies. One hundred twenty-five subjects were included. Median (interquartile range) sCD30 levels were lower on day 30 posttransplant compared with pretransplant [10.7 (3.7-20.1) pg/mL versus 66.5 (46.0-95.1) pg/mL; P < 0.0001]. On univariate analyses, day 30 sCD30 levels were negatively correlated with MPA exposure and positively correlated with tacrolimus exposure. Using multivariate logistic regression, higher tacrolimus exposure was independently associated with higher day 30 sCD30 levels (2.2 change in odds for an SD increase in tacrolimus AUC 0-12, P = 0.01; 5.5 change in odds for an SD increase in tacrolimus predose concentration, P < 0.0001). In contrast, MPA and total and free prednisolone exposures were not independently associated with sCD30 levels. The sCD30 levels are significantly reduced in the presence of combination immunosuppression but are differentially affected by different immunosuppressant agents. More research is required before introduction of sCD30 measurement into clinical practice can be considered.

Fatty acid ethyl esters (FAEE); comparative accumulation in human and guinea pig hair as a biomarker for prenatal alcohol exposure.

PubMed

Kulaga, Vivian; Caprara, Daniela; Iqbal, Umar; Kapur, Bhushan; Klein, Julia; Reynolds, James; Brien, James; Koren, Gideon

2006-01-01

To compare the incorporation rate (ICR) of fatty acid ethyl esters (FAEE) in hair between guinea pigs and humans, and to assess the relationship between ethanol exposure and FAEE concentrations in hair. Published data from pregnant guinea pigs, including maximum blood ethanol concentration (BEC), dosage regimen, and total hair FAEE concentration, were compared with published data from alcoholic patients, where dose of ethanol consumed and total hair FAEE concentration were reported. Mean values of ethanol Vmax for pregnant guinea pigs and humans were obtained from published data (26.2 and 24 mg/dl/h, respectively). Total and individual FAEE ICRs, defined as the ratio of hair FAEE to the area under the BEC-time curve (total systemic ethanol exposure), were found to be on average an order of magnitude lower in the guinea pig than in the human. The profiles of ester incorporation also differed slightly between species, with ethyl stearate being highly incorporated in guinea pig hair and less so in human hair. The results may reflect in the human greater FAEE production, greater FAEE deposition in hair, slower FAEE catabolism, differential sebum production and composition, or a combination thereof. Also, ethyl oleate was found to correlate with total systemic ethanol exposure for both guinea pigs and humans, correlation coefficients equalling 0.67 (P < 0.05) and 0.49 (P < 0.05), respectively. No other ethyl esters, nor total FAEE, were found to correlate with systemic ethanol exposure. When extrapolating FAEE concentrations in hair from guinea pigs to humans, an order of magnitude difference should be considered, with humans incorporating more FAEE per unit of ethanol exposure. Also, the results suggest caution should be taken when interpreting values of single esters because of their differential incorporation among species. Lastly, our findings suggest ethyl oleate may be of keen interest in FAEE hair analysis, particularly across species.

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.

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

New approach for assessing human perfluoroalkyl exposure via hair.

PubMed

Alves, Andreia; Jacobs, Griet; Vanermen, Guido; Covaci, Adrian; Voorspoels, Stefan

2015-11-01

In the recent years hair has been increasingly used as alternative matrix in human biomonitoring (HBM) of environmental pollutants. Sampling advantages and time integration of exposure assessment seems the most attractive features of hair matrix. In the current study, a novel miniaturized method was developed and validated for measuring 15 perfluoroalkyl substances (PFAS), including perfluoro n-butanoic acid (PFBA), perfluoro n-pentanoic acid (PFPeA), perfluoro n-hexanoic acid (PFHxA), perfluoro n-heptanoic acid (PFHpA), perfluor n-octanoic acid (PFOA), perfluoro n-nonanoic acid (PFNA), perfluoro tetradecanoic acid (PFTeDA), perfluorobutane sulfonic acid (PFBS), perfluoro pentane sulfonic acid (PFPeS), perfluorohexane sulfonic acid (PFHxS), perfluoroheptane sulfonic acid (PFHpS), perfluorooctane sulfonic acid (PFOS), perfluorononane sulfonic acid (PFNS), perfluorodecane sulfonic acid (PFDS) and perfluorododecane sulfonic acid (PFDoS) in human hair by liquid chromatography tandem mass spectrometry (LC-MS/MS). After extraction using ethyl acetate, dispersive ENVI-Carb was used for clean-up. Good intra- and inter-day precision for low (LQ 5 ng/g hair) and high spike (HQ 15n g/g) levels were achieved (in general RSD <10%). The accuracy was assessed using recoveries (%), which ranged between 68-118% (LQ) and 70-121% (HQ). The instrumental limit of detection (LODi) and limit of quantification (LOQi) were between 1-4 pg/g hair and 3-13 pg/g hair, respectively. The method limit of quantification (LOQm) ranged between 6 and 301 pg/g hair. The PFAS levels were measured in 30 human hair samples indicating that the levels are low (14-1534 pg/g hair). Some PFAS were not present in any hair sample (e.g. PFHpA, PFTeDA, PFNA, PFPeS, PFHpS, PFOS and PFNS), while other PFAS were frequently detected (PFBA, PFPeA, PFHxA, PFOA, PFBS, PFHxS, PFOS, PFDS and PFDoS) in human hair. Although levels in general were low, there is evidence of higher human exposure to some analytes, such as PFBA

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.

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

PubMed Central

Ferris, B G; Spengler, J D

1985-01-01

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. Images FIGURE 1. PMID:4076094

Time dependent inhibition of xanthine oxidase in irradiated solutions of folic acid, aminopterin and methotrexate

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 inmore » solution and the ability of these solutions to inhibit xanthine oxidase. The relative potency of the respective photolysis products were estimated.« less

Crop bioaccumulation and human exposure of perfluoroalkyl acids through multi-media transport from a mega fluorochemical industrial park, China.

PubMed

Liu, Zhaoyang; Lu, Yonglong; Shi, Yajuan; Wang, Pei; Jones, Kevin; Sweetman, Andrew J; Johnson, Andrew C; Zhang, Meng; Zhou, Yunqiao; Lu, Xiaotian; Su, Chao; Sarvajayakesavaluc, Suriyanarayanan; Khan, Kifayatullah

2017-09-01

Significant quantities of perfluoroalkyl acids (PFAAs) are released to the environment from fluorochemical manufacturing processes through wastewater discharge and air emission in China, which may lead to human exposure and health risks through crop bioaccumulation from PFAAs-contaminated soil and irrigation water. This paper systematically studied the distribution and transport of PFAAs in agricultural soil, irrigation water and precipitation, followed by crop bioaccumulation and finally human exposure of PFAAs within a 10km radius around a mega-fluorochemical industrial park (FIP). Hotspots of contamination by PFAAs were found near the FIP and downstream of the effluent discharge point with the maximum concentrations of 641ng/g in agricultural soil, 480ng/g in wheat grain, 58.8ng/g in maize grain and 4,862ng/L in precipitation. As the distance increased from the FIP, PFAAs concentrations in all media showed a sharp initial decrease followed by a moderate decline. Elevated PFAA concentrations in soil and grains were still present within a radius of 10 km of the FIP. The soil contamination was associated with the presence of PFAAs in irrigation water and precipitation, and perfluorooctanoic acid (PFOA) was the dominant PFAA component in soil. However, due to bioaccumulation preference, short-chain perfluoroalkyl carboxylic acids (PFCAs), especially perfluorobutanoic acid (PFBA), became the major PFAA contaminants in grains of wheat and maize. The bioaccumulation factors (BAFs) for both grains showed a decrease with increasing chain length of PFAAs (approximately 0.5 log decrease per CF 2 group). Compared to maize grain, wheat grain showed higher BAFs, possibly related to its higher protein content. The PFCA (C4-C8) concentrations (on a log 10 basis) in agricultural soil and grain were found to show a linear positive correlation. Local human exposure of PFOA via the consumption of contaminated grains represents a health risk for local residents, especially for

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 ...

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.

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

Neuroenhancement of Exposure Therapy in Anxiety Disorders

PubMed Central

Hofmann, Stefan G.; Mundy, Elizabeth A.; Curtiss, Joshua

2015-01-01

Although exposure-based treatments and anxiolytic medications are more effective than placebo for treating anxiety disorders, there is still considerable room for further improvement. Interestingly, combining these two modalities is usually not more effective than the monotherapies. Recent translational research has identified a number of novel approaches for treating anxiety disorders using agents that serve as neuroenhancers (also known as cognitive enhancers). Several of these agents have been studied to determine their efficacy at improving treatment outcome for patients with anxiety and other psychiatric disorders. In this review, we examine d-cycloserine, yohimbine, cortisol, catecholamines, oxytocin, modafinil, and nutrients such as caffeine and amino fatty acids as potential neuroenhancers. Of these agents, d-cycloserine shows the most promise as an effective neuroenhancer for extinction learning and exposure therapy. Yet, the optimal dosing and dose timing for drug administration remains uncertain. There is partial support for cortisol, catecholamines, yohimbine and oxytocin for improving extinction learning and exposure therapy. There is less evidence to indicate that modafinil and nutrients such as caffeine and amino fatty acids are effective neuroenhancers. More research is needed to determine their long term efficacy and clinical utility of these agents. PMID:26306326

Web-Based Survey Application to Collect Contextually Relevant Geographic Data With Exposure Times: Application Development and Feasibility Testing

PubMed Central

Tobin, Karin; Rudolph, Jonathan; Latkin, Carl

2018-01-01

Background Although studies that characterize the risk environment by linking contextual factors with individual-level data have advanced infectious disease and substance use research, there are opportunities to refine how we define relevant neighborhood exposures; this can in turn reduce the potential for exposure misclassification. For example, for those who do not inject at home, injection risk behaviors may be more influenced by the environment where they inject than where they live. Similarly, among those who spend more time away from home, a measure that accounts for different neighborhood exposures by weighting each unique location proportional to the percentage of time spent there may be more correlated with health behaviors than one’s residential environment. Objective This study aimed to develop a Web-based application that interacts with Google Maps application program interfaces (APIs) to collect contextually relevant locations and the amount of time spent in each. Our analysis examined the extent of overlap across different location types and compared different approaches for classifying neighborhood exposure. Methods Between May 2014 and March 2017, 547 participants enrolled in a Baltimore HIV care and prevention study completed an interviewer-administered Web-based survey that collected information about where participants were recruited, worked, lived, socialized, injected drugs, and spent most of their time. For each location, participants gave an address or intersection which they confirmed using Google Map and Street views. Geographic coordinates (and hours spent in each location) were joined to neighborhood indicators by Community Statistical Area (CSA). We computed a weighted exposure based on the proportion of time spent in each unique location. We compared neighborhood exposures based on each of the different location types with one another and the weighted exposure using analysis of variance with Bonferroni corrections to account for

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. © 2014 The Authors Clinical Microbiology and Infection © 2014 European Society of Clinical Microbiology and Infectious Diseases.

Effect of oxidant concentration, exposure time, and seed particles on secondary organic aerosol chemical composition and yield

NASA Astrophysics Data System (ADS)

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.; Kolb, C. E.; Davidovits, P.

2015-03-01

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 the 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 sulfate seed

Effect of oxidant concentration, exposure time, and seed particles on secondary organic aerosol chemical composition and yield

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lambe, A. T.; Chhabra, P. S.; Onasch, T. B.

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 × 10 8 to 2.2 × 10 10 molec cm -3 over exposure times of 100 s. In the environmental chambers, precursors were oxidized using OH concentrations ranging from 2 × 10 6 to 2 × 10 7 molec cm -3 over exposure times of severalmore » hours. The OH concentration in the 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 × 10 11 and 2 × 10 11 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

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.; ...

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 × 10 8 to 2.2 × 10 10 molec cm -3 over exposure times of 100 s. In the environmental chambers, precursors were oxidized using OH concentrations ranging from 2 × 10 6 to 2 × 10 7 molec cm -3 over exposure times of severalmore » hours. The OH concentration in the 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 × 10 11 and 2 × 10 11 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

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.

Human exposure to per- and polyfluoroalkyl substances (PFASs) via house dust in Korea: Implication to exposure pathway.

PubMed

Tian, Zhexi; Kim, Seung-Kyu; Shoeib, Mahiba; Oh, Jeong-Eun; Park, Jong-Eun

2016-05-15

A wide range of per- and polyfluoroalkyl substances (PFASs), including fluorotelomer alcohols (FTOHs), perfluorooctane sulfonamidoethanols (FOSEs), perfluoroalkyl carboxylic acids (PFCAs), and perfluoroalkane sulfonic acids (PFSAs), were measured in fifteen house dust and two nonresidential indoor dust of Korea. Total concentrations of PFASs in house dust ranged from 29.9 to 97.6 ng g(-1), with a dominance of perfluorooctane sulfonic acid (PFOS), followed by 8:2 FTOH, N-Ethyl perfluorooctane sulfonamidoethanol (EtFOSE), perfluoroctanoic acid (PFOA). In a typical exposure scenario, the estimated daily intakes (EDIs) of total PFASs via house dust ingestion were 2.83 ng d(-1) for toddlers and 1.13 ng d(-1) for adults, which were within the range of the mean EDIs reported from several countries. For PFOA and PFOS exposure via house dust ingestion, indirect exposure (via precursors) was a minor contributor, accounting for 5% and 12%, respectively. An aggregated exposure (hereafter, overall-EDIs) of PFOA and PFOS occurring via all pathways, estimated using data compiled from the literature, were 53.6 and 14.8 ng d(-1) for toddlers, and 20.5 and 40.6 ng d(-1) for adults, respectively, in a typical scenario. These overall-EDIs corresponded to 82% (PFOA) and 92% (PFOS) of a pharmacokinetic model-based EDIs estimated from adults' serum data. Direct dietary exposure was a major contributor (>89% of overall-EDI) to PFOS in both toddlers and adults, and PFOA in toddlers. As for PFOA exposure of adults, however direct exposure via tap water drinking (37%) and indirect exposure via inhalation (22%) were as important as direct dietary exposure (41%). House dust-ingested exposure (direct+indirect) was responsible for 5% (PFOS in toddlers) and <1% (PFOS in adults, and PFOA in both toddlers and adults) of the overall-EDIs. In conclusion, house-dust ingestion was a minor contributor in this study, but should not be ignored for toddlers' PFOS exposure due to its significance in the

Acute inhalative exposure assessment: derivation of guideline levels with special regard to sensitive subpopulations and time scaling.

PubMed

Mielke, Hans; Gundert, Anna; Abraham, Klaus; Gundert-Remy, Ursula

2005-10-30

Risk assessment for acute airborne exposure to volatile organic compounds (VOCs), including exposure to chemical warfare agents, requires consideration of local and systemic effects at high concentrations. The operating procedure developed by the US Acute Exposure Guideline Level (AEGL) committee has gained special attention, in part because of the international collaboration in the project. The procedure defines three levels (AEGL-1: discomfort; AEGL-2: irreversible or other serious, long-lasting adverse effects; AEGL-3: life-threatening effects or death) for different exposure times (10 and 30 min, and 1, 4 and 8 h). In this article, the methodology for deriving AEGL values is reported. Extending the areas covered by the existing AEGL methodology, sensitive subpopulations are dealt with in more detail. Sensitive persons are expected to suffer from stronger effects when exposed to a given external concentration. Using a kinetic model with the sample substance dichloromethane (DCM), the higher internal exposure of children is quantified and compared to a healthy, young adult. The difference is shown to depend on age, on dose, and on duration of exposure. Furthermore, several ways are presented to derive AEGL values for exposure times which differ from the exposure duration in animal studies ('time scaling'). In comparison to the conventional procedure, the alternative approaches are based on mechanistic models of the toxicodynamic effect. Use of these models results in AEGL values which are biologically justified.

Determinants of exposure to chemical pollutants in wet X-ray film processing in Iran.

PubMed

Kakooei, Hossein; Ardakani, Mehdi B; Sadighi, Alireza

2007-07-15

The aim of the current study was to measure glutaraldehyde, acetic acid and sulfur dioxide and levels inside wet x-ray processing areas in a developing country and comparing data with those in developed countries. Forty-five radiographers from 10 educational hospitals affiliated to the Tehran University of Medical Sciences (TUMS) in Tehran, Iran participated in this descriptive-analytical study. Exposure to glutaraldehyde (a constituent of developer chemistry), acetic acid (a constituent of fixer chemistry) and sulfur dioxide (a byproduct of sulfites present in both developer and fixer solutions) was measured in all participants as well as area exposure. Average full-shift exposure to glutaraldehyde, acetic acid and sulfur dioxide were 0.0018, 2.65 and 1.64 mg m(-1), respectively. The results showed that the TUMS radiographers full-shift exposures are generally lower than the American Conference of Governmental Industrial Hygienists (ACGIH) recommended levels. The concentration of glutaraldehyde collected by area sampling (darkroom) was almost five times (0.0104 mg m(-3)) greater than taken by personal sampling. Exposure to the chemical pollutants in the currents study were generally higher than in developed countries. Identification of these key exposure determinants is useful in targeting exposure evaluation and controls to reduce developer and fixer chemicals exposures in the radiology departments. Employing of a digital imaging system that do not involve wet x-ray processing of photographic film would be a useful device for radiographers protection.

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...

Evaluation of Renal Toxicity by Combination Exposure to Melamine and Cyanuric Acid in Male Sprague-Dawley Rats

PubMed Central

Son, Ji Yeon; Kang, Yoon Jong; Kim, Kyeong Seok; Kim, Tae Hyung; Lim, Sung Kwang; Lim, Hyun Jung; Jeong, Tae Cheon; Choi, Dal Woong; Chung, Kyu Hyuck; Lee, Byung Mu

2014-01-01

Melamine-induced nephrotoxicity is closely associated with crystal formation in the kidney caused by combined exposure to melamine (Mel) and cyanuric acid (CA). However, there are few dosage-finding studies for toxicological evaluation of chronic co-exposure to Mel and CA. The objective of this study was to investigate the possible mechanism by which a Mel and CA mixture lead to renal toxicity in rats. Mel and CA were co-administered to rats via oral gavage for 50 days. Nephrotoxicity was determined by measuring blood urea nitrogen (BUN) and serum creatinine (sCr) levels. Relative kidney weights were significantly increased in rats after co-exposure to Mel+CA (63/6.3 or 630/6.3 mg/kg) mixtures. BUN and sCr levels were significantly increased after Mel and CA co-exposure. Taken together, significant increase in KIM-1, NGAL, and calbindin levels were observed in the urine of rats exposed to Mel+CA (63/6.3 or 630/6.3 mg/kg) compared with the corresponding control group. Histological analysis revealed epithelial degeneration and necrotic cell death in the proximal tubules of the kidney after co-exposure to Mel+CA (63/6.3 or 630/6.3 mg/kg). Our data suggest that Mel-mediated renal toxicity may be influenced by CA concentrations in Mel-contaminated milk or foods. PMID:25071919

Exposure to 2,4-dichlorophenoxyacetic acid induces oxidative stress and apoptosis in mouse testis.

PubMed

Zhang, Dalei; Wu, Yaling; Yuan, Yangyang; Liu, Wenwen; Kuang, Haibin; Yang, Jianhua; Yang, Bei; Wu, Lei; Zou, Weiying; Xu, Changshui

2017-09-01

The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) is used worldwide. It has been associated with a variety of toxicities in rodents. In this study, male mice were orally administered 2,4-D at 50, 100 or 200mg/kg/day to investigate testicular toxicity and the possible mechanisms of action. Exposure to 2,4-D at high concentrations (100 and 200mg/kg/day) for 14 consecutive days caused spermatogenic disruption and seminiferous epithelial destruction. Furthermore, 2,4-D administration (100 and 200mg/kg/day) increased the formation of the lipid peroxidation product malondialdehyde and decreased activities of the antioxidant enzymes superoxide dismutase and catalase in the testis. Moreover, 2,4-D exposure up-regulated the expression of p53 and Bax protein and down-regulated the expression of Bcl-2 protein in the testis. These results demonstrate that oxidative stress and apoptosis may be involved in testicular toxicity induced by high concentrations of 2,4-D in mice. Copyright © 2016 Elsevier Inc. All rights reserved.

Systemic exposure to benzoic acid and hippuric acid following topical application of clindamycin 1%/benzoyl peroxide 3% fixed-dose combination gel in Japanese patients with acne vulgaris.

PubMed

Ino, Hiroko; Takahashi, Naoki; Saenz, Alessandra Alio; Wakamatsu, Akira; Hashimoto, Hirofumi; Nakahara, Norie; Hasegawa, Setsuo

2015-01-01

Clindamycin 1%/benzoyl peroxide 3% fixed-dose combination gel (CLDM/BPO3%) is a topical product for the treatment of acne vulgaris. In this study, plasma and urine concentrations of benzoic acid (BA) and hippuric acid (HA) were analyzed to estimate the pharmacokinetics (PK) of BPO after application of CLDM/BPO3% twice-daily for 7 days in Japanese patients with acne vulgaris. Seven-day repeated application of CLDM/BPO3% appears to be safe in this patient population. Concentrations of plasma and urine BA were below the limit of quantification before and after repeated application in most of the 12 adult male patients. Mean difference in Cmax and AUC0-last for plasma HA indicated increased exposures after repeated application, but with wide 90% confidence intervals. Mean Ae0-12 for urine HA was similar before and after repeated application. Repeated application of CLDM/BPO3% is thus unlikely to result in accumulation of BA and HA. The study suggests negligible systemic exposure to BPO metabolites from CLDM/BPO3% after 7-day repeated application in male patients with acne vulgaris. © 2014, The American College of Clinical Pharmacology.

The Effects of Subacute Exposure of Peracetic Acid on Lipid Peroxidation and Hepatic Enzymes in Wistar Rats

PubMed Central

Marjani, Abdoljalal; Golalipour, Mohammad J.; Gharravi, Anneh M.

2010-01-01

Objectives This study was undertaken to determine the effect of subacute exposure of peracetic acid on lipid peroxidation and hepatic enzymes in Wistar rats. Methods 48 male animals in Treatment Group I, II and III received 0.2%, 2% and 20% peracetic acid daily for 2 and 4 weeks. Results Serum malondialdehyde increased and Alanine Transaminase and Aspartate Transaminase decreased significantly in groups 2 and 3, compared to the control group. The malondialdehyde, Alanine Transaminase and Aspartate Transaminase with 0.2% and 2% doses of peracetic acid for 2 weeks do not lead to the alteration of malondialdehyde and enzyme activities. Conclusion This study demonstrated that the enhancement of malondialdehyde could provide an oxidative damage induced by disinfectant peroxidation at 20% and 2% doses at 2 and 4 weeks. The consumption of peroxidation with 20% for 2 weeks and 2% for 4 weeks can cause the increase of malondialdehyde and the decrease of enzyme activities, respectively. PMID:22043353

Stearic Acid

ERIC Educational Resources Information Center

Young, Jay A.

2004-01-01

A chemical laboratory information profile (CLIP) is presented for the chemical, stearic acid. The profile lists the chemical's physical and harmful characteristics, exposure limits, and symptoms of major exposure, for the benefit of teachers and students, who use the chemical in the laboratory.

Polymorphisms of delta-aminolevulinic acid dehydratase (ALAD) and peptide transporter 2 (PEPT2) genes in children with low-level lead exposure

PubMed Central

Sobin, Christina; Gutierrez, Marisela; Alterio, Heather

2009-01-01

Low-level lead exposure during early childhood has long been associated with altered neurocognitive development and diminished cognitive functions. Over nine thousand U.S. industrial facilities annually emit significant amounts of lead, creating exposure risk particularly for minority children. The mechanisms by which low-level lead exerts neurotoxic effects are poorly understood. Once absorbed, the only intervention is source removal, thus primary prevention is key. Genetic biomarkers could provide an efficient means of identifying children at greatest risk. Common functional variants of genes that alter lead's neurotoxic potential have been identified and include delta-aminolevulinic acid dehydratase (ALAD2) and peptide transporter 2 (PEPT2*2). These polymorphisms have not been examined previously in Hispanic minority samples, or with regard to lowest level lead exposure. In 116 children of Mexican-American/Hispanic descent residing in zip codes previously designated as “high risk” for lead exposure (mean age = 8.1, S.D. = 1.9), blood lead level was measured at three time points over a 3-month period and averaged. DNA extraction was completed using buccal swab samples. The frequencies of the ALAD2 and PEPT2*2 polymorphisms observed in this sample closely approximated those previously reported for Anglo, European and Asian samples. As compared to children heterozygous for the PEPT2*2 polymorphism, and without the PEPT2*2 polymorphism, the geometric mean blood lead level of children homozygous for the PEPT2*2 polymorphism was significantly higher. In contrast to past studies, mean blood lead level of children heterozygous and homozygous for the ALAD2 polymorphism in this sample did not differ from that of children without the ALAD2 polymorphism. Higher blood lead burden in children with the PEPT2*2 mutation may suggest that this common genetic variant is a biomarker of increased vulnerability to the neurotoxic effects of lowest level lead exposure. PMID

Impacts of short-term acid and aluminum exposure on Atlantic salmon (Salmo salar) physiology: A direct comparison of parr and smolts

USGS Publications Warehouse

Monette, M.Y.; McCormick, S.D.

2008-01-01

Episodic acidification resulting in increased acidity and inorganic aluminum (Ali) is known to impact anadromous salmonids and has been identified as a possible cause of Atlantic salmon population decline. Sensitive life-stages such as smolts may be particularly vulnerable to impacts of short-term (days–week) acid/Al exposure, however the extent and mechanism(s) of this remain unknown. To determine if Atlantic salmon smolts are more sensitive than parr to short-term acid/Al, parr and smolts held in the same experimental tanks were exposed to control (pH 6.3–6.6, 11–37 μg l−1 Ali) and acid/Al (pH 5.0–5.4, 43–68 μg l−1 Ali) conditions in the lab, and impacts on ion regulation, stress response and gill Al accumulation were examined after 2 and 6 days. Parr and smolts were also held in cages for 2 and 6 days in a reference (Rock River, RR) and an acid/Al-impacted tributary (Ball Mountain Brook, BMB) of the West River in Southern Vermont. In the lab, losses in plasma Cl− levels occurred in both control parr and smolts as compared to fish sampled prior to the start of the study, however smolts exposed to acid/Al experienced additional losses in plasma Cl− levels (9–14 mM) after 2 and 6 days, and increases in plasma cortisol (4.3-fold) and glucose (2.9-fold) levels after 6 days, whereas these parameters were not significantly affected by acid/Al in parr. Gill Na+,K+-ATPase (NKA) activity was not affected by acid/Al in either life-stage. Both parr and smolts held at BMB (but not RR) exhibited declines in plasma Cl−, and increases in plasma cortisol and glucose levels; these differences were significantly greater in smolts after 2 days but similar in parr and smolts after 6 days. Gill NKA activity was reduced 45–54% in both life-stages held at BMB for 6 days compared to reference fish at RR. In both studies, exposure to acid/Al resulted in gill Al accumulation in parr and smolts, with parr exhibiting two-fold greater gill Al than smolts after 6

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.

Acidic Mammalian Chitinase Negatively Affects Immune Responses during Acute and Chronic Aspergillus fumigatus Exposure.

PubMed

Garth, Jaleesa M; Mackel, Joseph J; Reeder, Kristen M; Blackburn, Jonathan P; Dunaway, Chad W; Yu, Zhihong; Matalon, Sadis; Fitz, Lori; Steele, Chad

2018-07-01

Chitin is a polysaccharide that provides structure and rigidity to the cell walls of fungi and insects. Mammals possess multiple chitinases, which function to degrade chitin, thereby supporting a role for chitinases in immune defense. However, chitin degradation has been implicated in the pathogenesis of asthma. Here, we determined the impact of acidic mammalian chitinase (AMCase) ( Chia ) deficiency on host defense during acute exposure to the fungal pathogen Aspergillus fumigatus as well as its contribution to A. fumigatus -associated allergic asthma. We demonstrate that chitin in the fungal cell wall was detected at low levels in A. fumigatus conidia, which emerged at the highest level during hyphal transition. In response to acute A. fumigatus challenge, Chia -/- mice unexpectedly demonstrated lower A. fumigatus lung burdens at 2 days postchallenge. The lower fungal burden correlated with decreased lung interleukin-33 (IL-33) levels yet increased IL-1β and prostaglandin E 2 (PGE 2 ) production, a phenotype that we reported previously to promote the induction of IL-17A and IL-22. During chronic A. fumigatus exposure, AMCase deficiency resulted in lower dynamic and airway lung resistance than in wild-type mice. Improved lung physiology correlated with attenuated levels of the proallergic chemokines CCL17 and CCL22. Surprisingly, examination of inflammatory responses during chronic exposure revealed attenuated IL-17A and IL-22 responses, but not type 2 responses, in the absence of AMCase. Collectively, these data suggest that AMCase functions as a negative regulator of immune responses during acute fungal exposure and is a contributor to fungal asthma severity, putatively via the induction of proinflammatory responses. Copyright © 2018 American Society for Microbiology.

Cellular Effects of Perfluorinated Fatty Acids (PFDA).

DTIC Science & Technology

This is a proposal to investigate the effects of perfluorinated decanoic acid ( PFDA ) on the cell surface of liver cells and tissue. The major method...summarized as follows: (a) differentiated liver tissue culture cells in vitro do have the membrane fluidity affected by PFDA whereas undifferentiated, non...d) the effect on mobility occurs within 24 hours of exposure without further increase with time of exposure; (e) scanning EM demonstrates no gross structural abnormality of the surface as a result of the non-toxic levels of PFDA .

Nocturnal weakly acidic reflux promotes aspiration of bile acids in lung transplant recipients.

PubMed

Blondeau, Kathleen; Mertens, Veerle; Vanaudenaerde, Bart A; Verleden, Geert M; Van Raemdonck, Dirk E; Sifrim, Daniel; Dupont, Lieven J

2009-02-01

Gastroesophageal reflux (GER) and aspiration of bile acids have been implicated as non-alloimmune risk factors for the development of bronchiolitis obliterans syndrome (BOS) after lung transplantation. The aim of our study was to investigate the association between GER and gastric aspiration of bile acids and to establish which reflux characteristics may promote aspiration of bile acids into the lungs and may feature as a potential diagnostic tool in identifying lung transplantation (LTx) patients at risk for aspiration. Twenty-four stable LTx recipients were studied 1 year after transplantation. All patients underwent 24-hour ambulatory impedance-pH recording for the detection of acid (pH <4) and weakly acidic (pH 4 to 7) reflux. On the same day, bronchoalveolar lavage fluid (BALF) was collected and then analyzed for the presence of bile acids (Bioquant enzymatic assay). Increased GER was detected in 13 patients, of whom 9 had increased acid reflux and 4 had exclusively increased weakly acidic reflux. Sixteen patients had detectable bile acids in the BALF (0.6 [0.4 to 1.5] micromol/liter). The 24-hour esophageal volume exposure was significantly increased in patients with bile acids compared to patients without bile acids in the BALF. Acid exposure and the number of reflux events (total, acid and weakly acidic) were unrelated to the presence of bile acids in the BALF. However, both nocturnal volume exposure and the number of nocturnal weakly acidic reflux events were significantly higher in patients with bile acids in the BALF. Weakly acidic reflux events, especially during the night, are associated with the aspiration of bile acids in LTx recipients and may therefore feature as a potential risk factor for the development of BOS.

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. Copyright © 2015 Elsevier Ltd. All rights reserved.

Sampling and analysis of airborne resin acids and solvent-soluble material derived from heated colophony (rosin) flux: a method to quantify exposure to sensitizing compounds liberated during electronics soldering.

PubMed

Smith, P A; Son, P S; Callaghan, P M; Jederberg, W W; Kuhlmann, K; Still, K R

1996-07-17

Components of colophony (rosin) resin acids are sensitizers through dermal and pulmonary exposure to heated and unheated material. Significant work in the literature identifies specific resin acids and their oxidation products as sensitizers. Pulmonary exposure to colophony sensitizers has been estimated indirectly through formaldehyde exposure. To assess pulmonary sensitization from airborne resin acids, direct measurement is desired, as the degree to which aldehyde exposure correlates with that of resin acids during colophony heating is undefined. Any analytical method proposed should be applicable to a range of compounds and should also identify specific compounds present in a breathing zone sample. This work adapts OSHA Sampling and Analytical Method 58, which is designed to provide airborne concentration data for coal tar pitch volatile solids by air filtration through a glass fiber filter, solvent extraction of the filter, and gravimetric analysis of the non-volatile extract residue. In addition to data regarding total soluble material captured, a portion of the extract may be subjected to compound-specific analysis. Levels of soluble solids found during personal breathing zone sampling during electronics soldering in a Naval Aviation Depot ranged from below the "reliable quantitation limit" reported in the method to 7.98 mg/m3. Colophony-spiked filters analyzed in accordance with the method (modified) produced a limit of detection for total solvent-soluble colophony solids of 10 micrograms/filter. High performance liquid chromatography was used to identify abietic acid present in a breathing zone sample.

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

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

Effects of sublethal exposure to boric acid sugar bait on adult survival, host-seeking, bloodfeeding behavior, and reproduction of Stegomyia albopicta.

PubMed

Ali, Arshad; Xue, Rui-De; Barnard, Donald R

2006-09-01

Effects of sublethal exposure to 0.1% boric acid sugar bait on adult survival, host-seeking, bloodfeeding behavior, and reproduction of Stegomyia albopicta were studied in the laboratory. Survival of males as well as females was significantly reduced when exposed to the bait, compared to control adults. The host-seeking and bloodfeeding activities in the baited females decreased, but the mean duration of blood engorgement (probing to voluntary withdrawal of proboscis) was not significantly different between the baited and control females. The landing and biting rates (human forearm) were significantly reduced in the baited females compared to nonbaited controls. Fecundity and fertility (based on number of laid eggs per female and percentage egg hatch, respectively) in the baited females were significantly reduced, and ovarian development was retarded. Sublethal exposure to sugar-based boric acid bait has the potential to reduce adult populations of St. albopicta.

Design and application of a web-based real-time personal PM2.5 exposure monitoring system.

PubMed

Sun, Qinghua; Zhuang, Jia; Du, Yanjun; Xu, Dandan; Li, Tiantian

2018-06-15

Growing demand from public health research for conduct large-scale epidemiological studies to explore health effect of PM 2.5 was well-documented. To address this need, we design a web-based real-time personal PM 2.5 exposure monitoring system (RPPM2.5 system) which can help researcher to get big data of personal PM 2.5 exposure with low-cost, low labor requirement, and low operating technical requirements. RPPM2.5 system can provide relative accurate real-time personal exposure data for individuals, researches, and decision maker. And this system has been used in a survey of PM 2.5 personal exposure level conducted in 5 cities of China and has provided mass of valuable data for epidemiological research. Copyright © 2018 Elsevier B.V. All rights reserved.

Valproic acid exposure sequentially activates Wnt and mTOR pathways in rats.

PubMed

Qin, Liyan; Dai, Xufang; Yin, Yunhou

2016-09-01

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impaired social interaction, limited verbal communication and repetitive behaviors. Recent studies have demonstrated that Wnt signaling and mTOR signaling play important roles in the pathogenesis of ASD. However, the relationship of these two signaling pathways in ASD remains unclear. We assessed this question using the valproic acid (VPA) rat model of autism. Our results demonstrated that VPA exposure activated mTOR signaling and suppressed autophagy in the prefrontal cortex, hippocampus and cerebellum of autistic model rats, characterized by enhanced phospho-mTOR and phospho-S6 and decreased Beclin1, Atg5, Atg10, LC3-II and autophagosome formation. Rapamycin treatment suppressed the effect of VPA on mTOR signaling and ameliorated the autistic-like behaviors of rats in our autism model. The administration of VPA also activated Wnt signaling through up-regulating beta-catenin and phospho-GSK3beta. Suppression of the Wnt pathway by sulindac relieved autistic-like behaviors and attenuated VPA-induced mTOR signaling activation in autistic model rats. Our results demonstrate that VPA exposure sequentially activates Wnt signaling and mTOR signaling in rats. Suppression of the Wnt signaling pathway relieves autistic-like behaviors partially by deactivating the mTOR signaling pathway in VPA-exposed rats. Copyright © 2016 Elsevier Inc. All rights reserved.

Thermal performance curves, phenotypic plasticity, and the time scales of temperature exposure.

PubMed

Schulte, Patricia M; Healy, Timothy M; Fangue, Nann A

2011-11-01

Thermal performance curves (TPCs) describe the effects of temperature on biological rate processes. Here, we use examples from our work on common killifish (Fundulus heteroclitus) to illustrate some important conceptual issues relating to TPCs in the context of using these curves to predict the responses of organisms to climate change. Phenotypic plasticity has the capacity to alter the shape and position of the TPCs for acute exposures, but these changes can be obscured when rate processes are measured only following chronic exposures. For example, the acute TPC for mitochondrial respiration in killifish is exponential in shape, but this shape changes with acclimation. If respiration rate is measured only at the acclimation temperature, the TPC is linear, concealing the underlying mechanistic complexity at an acute time scale. These issues are particularly problematic when attempting to use TPCs to predict the responses of organisms to temperature change in natural environments. Many TPCs are generated using laboratory exposures to constant temperatures, but temperature fluctuates in the natural environment, and the mechanisms influencing performance at acute and chronic time scales, and the responses of the performance traits at these time scales may be quite different. Unfortunately, our current understanding of the mechanisms underlying the responses of organisms to temperature change is incomplete, particularly with respect to integrating from processes occurring at the level of single proteins up to whole-organism functions across different time scales, which is a challenge for the development of strongly grounded mechanistic models of responses to global climate change. © The Author 2011. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved.

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

2014-10-07

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.

Preventive effect of a high fluoride toothpaste and arginine-carbonate toothpaste on dentinal tubules exposure followed by acid challenge: a dentine permeability evaluation

PubMed Central

2014-01-01

Background Considering the current high use of high fluoride toothpastes, the aim of the study was to quantify alterations in the root dentine permeability submitted to treatment with a high fluoride toothpaste and 8% arginine, calcium carbonate, sodium monofluorophosphate toothpaste as a preventive treatment for dentinal tubules exposure followed by acid challenge. Methods Thirty-third molars were sectioned below the cementoenamel. The root segments were connected to a hydraulic pressure apparatus to measure dentine permeability after the following sequential steps (n = 10 per group): I) Baseline; II) treatment with phosphoric acid for 30 s (maximum permeability); III) Toothbrushing (1 min) according to the experimental groups (G1- control; G2- 5000 ppm fluoride toothpaste; G3- 8% arginine-calcium carbonate toothpaste); IV) acid challenge for 5 min (orange juice). The data were converted into percentage, considering stage II as 100%. Results The results have shown a statistically significant decreasing on dentine permeability after treatment with toothpaste (Friedman test and Dunn’s post hoc test). Comparison among groups demonstrated a high increasing on dentine permeability when acid challenge was performed after toothbrushing with distilled water (control group) (Kruskal-Wallis and Dunn’s post hoc test). Conclusion The toothpaste treatment may provide sufficient resistance on dentine surface, preventing dentinal tubules exposure after acid challenge. PMID:24958423

Vascular and nerve damage in workers exposed to vibrating tools. The importance of objective measurements of exposure time.

PubMed

Gerhardsson, Lars; Balogh, Istvan; Hambert, Per-Arne; Hjortsberg, Ulf; Karlsson, Jan-Erik

2005-01-01

The aim of the present study was to compare the development of vibration white fingers (VWF) in workers in relation to different ways of exposure estimation, and their relationship to the standard ISO 5349, annex A. Nineteen vibration exposed (grinding machines) male workers completed a questionnaire followed by a structured interview including questions regarding their estimated hand-held vibration exposure. Neurophysiological tests such as fractionated nerve conduction velocity in hands and arms, vibrotactile perception thresholds and temperature thresholds were determined. The subjective estimation of the mean daily exposure-time to vibrating tools was 192 min (range 18-480 min) among the workers. The estimated mean exposure time calculated from the consumption of grinding wheels was 42 min (range 18-60 min), approximately a four-fold overestimation (Wilcoxon's signed ranks test, p<0.001). Thus, objective measurements of the exposure time, related to the standard ISO 5349, which in this case were based on the consumption of grinding wheels, will in most cases give a better basis for adequate risk assessment than self-exposure assessment.

Developmental PCB Exposure Increases Audiogenic Seizures and Decreases Glutamic Acid Decarboxylase in the Inferior Colliculus.

PubMed

Bandara, Suren B; Eubig, Paul A; Sadowski, Renee N; Schantz, Susan L

2016-02-01

Previously, we observed that developmental polychlorinated biphenyl (PCB) exposure resulted in an increase in audiogenic seizures (AGSs) in rats. However, the rats were exposed to loud noise in adulthood, and were not tested for AGS until after 1 year of age, either of which could have interacted with early PCB exposure to increase AGS susceptibility. This study assessed susceptibility to AGS in young adult rats following developmental PCB exposure alone (without loud noise exposure) and investigated whether there was a decrease in GABA inhibitory neurotransmission in the inferior colliculus (IC) that could potentially explain this effect. Female Long-Evans rats were dosed orally with 0 or 6 mg/kg/day of an environmentally relevant PCB mixture from 28 days prior to breeding until the pups were weaned at postnatal day 21. One male-female pair from each litter was retained for the AGS study whilst another was retained for Western blot analysis of glutamic acid decarboxylase (GAD) and GABAAα1 receptor in the IC, the site in the auditory midbrain where AGS are initiated. There was a significant increase in the number and severity of AGSs in the PCB groups, with females somewhat more affected than males. GAD65 was decreased but there was no change in GAD67 or GABAAα1 in the IC indicating decreased inhibitory regulation in the PCB group. These results confirm that developmental PCB exposure alone is sufficient to increase susceptibility to AGS, and provide the first evidence for a possible mechanism of action at the level of the IC. © The Author 2015. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Hexavalent chromium exposures during full-aircraft corrosion control.

PubMed

Carlton, Gary N

2003-01-01

Aluminum alloys used in the construction of modern aircraft are subject to corrosion. The principal means of controlling this corrosion in the U.S. Air Force are organic coatings. The organic coating system consists of a chromate conversion coat, epoxy resin primer, and polyurethane enamel topcoat. Hexavalent chromium (CrVI) is present in the conversion coat in the form of chromic acid and in the primer in the form of strontium chromate. CrVI inhalation exposures can occur when workers spray conversion coat onto bare metal and apply primer to the treated metal surface. In addition, mechanical abrasion of aircraft surfaces can generate particulates that contain chromates from previously applied primers and conversion coats. This study measured CrVI exposures during these corrosion control procedures. Mean time-weighted average (TWA) exposure to chromic acid during conversion coat treatment was 0.48 microg/m(3), below the current American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV(R)) TWA of 50 microg/m(3) for water-soluble CrVI compounds. Mean TWA exposures to strontium chromate were 5.33 microg/m(3) during mechanical abrasion and 83.8 microg/m(3) during primer application. These levels are in excess of the current ACGIH TLV-TWA of 0.5 microg/m(3) for strontium chromate. In the absence of a change from chromated to nonchromated conversion coats and primers, additional control measures are needed to reduce these exposures.

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.

Long-term exposure to nicotine markedly reduces kynurenic acid in rat brain - In vitro and ex vivo evidence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zielinska, Elzbieta; Kuc, Damian; Zgrajka, Wojciech

Kynurenic acid (KYNA) is a recognized broad-spectrum antagonist of excitatory amino acid receptors with a particularly high affinity for the glycine co-agonist site of the N-methyl-D-aspartate (NMDA) receptor complex. KYNA is also a putative endogenous neuroprotectant. Recent studies show that KYNA strongly blocks {alpha}7 subtype of nicotinic acetylcholine receptors (nAChRs). The present studies were aimed at assessing effects of acute and chronic nicotine exposure on KYNA production in rat brain slices in vitro and ex vivo. In brain slices, nicotine significantly increased KYNA formation at 10 mM but not at 1 or 5 mM. Different nAChR antagonists (dihydro-{beta}-erythroidine, methyllycaconitine andmore » mecamylamine) failed to block the influence exerted by nicotine on KYNA synthesis in cortical slices in vitro. Effects of acute (1 mg/kg, i.p.), subchronic (10-day) and chronic (30-day) administration of nicotine in drinking water (100 {mu}g/ml) on KYNA brain content were evaluated ex vivo. Acute treatment with nicotine (1 mg/kg i.p.) did not affect KYNA level in rat brain. The subchronic exposure to nicotine in drinking water significantly increased KYNA by 43%, while chronic exposure to nicotine resulted in a reduction in KYNA by 47%. Co-administration of mecamylamine with nicotine in drinking water for 30 days reversed the effect exerted by nicotine on KYNA concentration in the cerebral cortex. The present results provide evidence for the hypothesis of reciprocal interaction between the nicotinic cholinergic system and the kynurenine pathway in the brain.« less

Fight and air exposure times of caught and released salmonids from the South Fork Snake River

USGS Publications Warehouse

Roth, Curtis J.; Schill, Daniel J.; Quist, Michael C.

2018-01-01

Catch-and-release regulations are among the most common types of fishing regulations. In recent years, concerns have arisen regarding the exposure of fish to air during catch-and-release angling. The purpose of our study was to quantify the length of time angled fish were exposed to air by anglers in a typical catch-and-release fishery and relate it to the lengths of time reported to produce negative effects. In total, 312 individual anglers were observed on the South Fork Snake River, Idaho, from May through August 2016. Fight time varied from 1.1 s to 230.0 s, and average fight time was 40.0 s (SD = 36.8). Total air exposure times varied from 0.0 s to 91.8 s and averaged 19.3 s (SD = 15.0). Though not statistically significant, a trend in reduced fight times was observed when anglers were guided and increased air exposure times when a net was used and a picture was taken. Results of the current study suggest that anglers expose fish to air for periods that are much less than those reported to cause mortality.

Effect of Exposure Type and Timing of Injuries in Division I College Football: A 4-year Single Program Analysis.

PubMed

Krill, Michael K; Borchers, James R; Hoffman, Joshua T; Tatarski, Rachel L; Hewett, Timothy E

2017-02-01

Football players compete with a high risk of injury due to the sport. With the recent efforts to improve safety, the National Collegiate Athletic Association (NCAA) established new terminology to clearly define exposure types and reduce the number of high contact exposures. To compare football injury rates (IR) with a focus on game versus practice, time in season of injury, mechanism of injury and utilizing recent exposure types defined by the NCAA (live contact, full-pads and non-contact). Licensed medical professionals monitored a college football program regular season from 2012-2015. Each injury was classified by timing of the injury, mechanism of injury, and whether it occurred in game or practice. Player attendance and type of exposure (non-contact, full-pad or live contact, which involves live tackling to the ground and/or full-speed blocking and can occur in full-pad or half-pad ('shell') equipment) was documented. IR were calculated per 1000 athlete-exposures (AE). Mid-exact P tests compared rates between variables. The game IR was over three times as high as the practice IR (p < .001). Live contact exposures had the greatest IR of 5.702/1000 AE and were seven times more likely to produce an injury compared to non-contact exposures (p < .001); whereas, live contact exposures were about two times more likely to produce an injury compared to full-pad exposures (p = .004). The majority of injuries observed occurred from a contact mechanism (IR: 2.508/1000 AE). The highest IR during the fall football season occurred in the pre-season at 5.769/1000 AE. Overall IR observed in this cohort were lower than prior studies published before recent NCAA rule changes and guideline implementation to improve athlete safety. Athletes in this cohort were at significantly increased risk of injury from live contact exposures.

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

The Characteristics of Postprandial Proximal Gastric Acid Pocket in Gastroesophageal Reflux Disease

PubMed Central

Wu, Jing; Liu, Dong; Feng, Cheng; Luo, Yumei; Nian, Yuanyuan; Wang, Xueqin; Zhang, Jun

2018-01-01

Background Postprandial proximal gastric acid pocket (PPGAP) plays important roles in gastroesophageal reflux disease (GERD). In this study, we analyzed the characteristics of PPGAP in GERD. Material/Methods There were 17 normal participants and 20 GERD patients who completed a gastroesophageal reflux disease questionnaire (GerdQ) and underwent a gastroscopy, a high-resolution manometry, an esophageal 24-hour pH monitoring, and a station pull-through pH monitoring to assess their symptomatic degree, endoscopic change, acid exposure, and PPGAP. Results PPGAP was present in all participants. Compared with normal participants, the PPGAP in GERD patients was significantly different, thus the disappearing time was significantly later (p<0.001), the lasting time was significantly longer (p<0.001), the length was significantly longer (p<0.001), and the lowest pH and the mean pH were significantly lower (p<0.001). The length of PPGAP in GERD patients was positively correlated with GerdQ score (p<0.05). The disappearing time, the lasting time, and the length of PPGAP in GERD patients was positively correlated with the DeMeester score (p<0.01). The lowest pH and the mean pH of PPGAP in GERD patients was negatively correlated with the DeMeester score (p<0.001). Conclusions PPGAP was generally present. PPGAP in GERD patients had characteristics of long time period, long length, and high acidity. Its length was positively correlated with subjective symptomatic degree. Its period, length, and acidity were positively correlated with the objective acid exposure. PPGAP seems to be the originator of acid reflux events and plays important roles in GERD. PMID:29309401

Cartilage and bone malformations in the head of zebrafish (Danio rerio) embryos following exposure to disulfiram and acetic acid hydrazide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strecker, Ruben, E-mail: Ruben.Strecker@cos.uni-heidelberg.de; Weigt, Stefan, E-mail: stefan.weigt@merckgroup.com; Braunbeck, Thomas, E-mail: braunbeck@uni-hd.de

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 fracturesmore » 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.« less

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

Developmental subchronic exposure to diphenylarsinic acid induced increased exploratory behavior, impaired learning behavior, and decreased cerebellar glutathione concentration in rats.

PubMed

Negishi, Takayuki; Matsunaga, Yuki; Kobayashi, Yayoi; Hirano, Seishiro; Tashiro, Tomoko

2013-12-01

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.

The AMINO experiment: exposure of amino acids in the EXPOSE-R experiment on the International Space Station and in laboratory

NASA Astrophysics Data System (ADS)

Bertrand, Marylène; Chabin, Annie; Colas, Cyril; Cadène, Martine; Chaput, Didier; Brack, Andre; Cottin, Herve

2015-01-01

In order to confirm the results of previous experiments concerning the chemical behaviour of organic molecules in the space environment, organic molecules (amino acids and a dipeptide) in pure form and embedded in meteorite powder were exposed in the AMINO experiment in the EXPOSE-R facility onboard the International Space Station. After exposure to space conditions for 24 months (2843 h of irradiation), the samples were returned to the Earth and analysed in the laboratory for reactions caused by solar ultraviolet (UV) and other electromagnetic radiation. Laboratory UV exposure was carried out in parallel in the Cologne DLR Center (Deutsches Zentrum für Luft und Raumfahrt). The molecules were extracted from the sample holder and then (1) derivatized by silylation and analysed by gas chromatography coupled to a mass spectrometer (GC-MS) in order to quantify the rate of degradation of the compounds and (2) analysed by high-resolution mass spectrometry (HRMS) in order to understand the chemical reactions that occurred. The GC-MS results confirm that resistance to irradiation is a function of the chemical nature of the exposed molecules and of the wavelengths of the UV light. They also confirm the protective effect of a coating of meteorite powder. The most altered compounds were the dipeptides and aspartic acid while the most robust were compounds with a hydrocarbon chain. The MS analyses document the products of reactions, such as decarboxylation and decarbonylation of aspartic acid, taking place after UV exposure. Given the universality of chemistry in space, our results have a broader implication for the fate of organic molecules that seeded the planets as soon as they became habitable as well as for the effects of UV radiation on exposed molecules at the surface of Mars, for example.

Real-time electrochemical monitoring of isothermal helicase-dependent amplification of nucleic acids.

PubMed

Kivlehan, Francine; Mavré, François; Talini, Luc; Limoges, Benoît; Marchal, Damien

2011-09-21

We described an electrochemical method to monitor in real-time the isothermal helicase-dependent amplification of nucleic acids. The principle of detection is simple and well-adapted to the development of portable, easy-to-use and inexpensive nucleic acids detection technologies. It consists of monitoring a decrease in the electrochemical current response of a reporter DNA intercalating redox probe during the isothermal DNA amplification. The method offers the possibility to quantitatively analyze target nucleic acids in less than one hour at a single constant temperature, and to perform at the end of the isothermal amplification a DNA melt curve analysis for differentiating between specific and non-specific amplifications. To illustrate the potentialities of this approach for the development of a simple, robust and low-cost instrument with high throughput capability, the method was validated with an electrochemical system capable of monitoring up to 48 real-time isothermal HDA reactions simultaneously in a disposable microplate consisting of 48-electrochemical microwells. Results obtained with this approach are comparable to that obtained with a well-established but more sophisticated and expensive fluorescence-based method. This makes for a promising alternative detection method not only for real-time isothermal helicase-dependent amplification of nucleic acid, but also for other isothermal DNA amplification strategies.

In-situ real time measurements of net erosion rates of copper during hydrogen plasma exposure

NASA Astrophysics Data System (ADS)

Kesler, Leigh; Wright, Graham; Peterson, Ethan; Whyte, Dennis

2013-10-01

In order to properly understand the dynamics of net erosion/deposition in fusion reactors, such as tokamaks, a diagnostic measuring the real time rates of net erosion/deposition during plasma exposure is necessary. The DIONISOS experiment produces real time measurements of net erosion/deposition by using Rutherford backscattering spectroscopy (RBS) ion beam analysis simultaneously with plasma exposure from a helicon plasma source. This in-situ method improves on ex-situ weight loss measurements by allowing measurement of possible synergistic effects of high ion implantation rates and net erosion rate and by giving a real time response to changes in plasma parameters. Previous work has validated this new technique for measuring copper (Cu) erosion from helium (He) plasma ion bombardment. This technique is now extended to measure copper erosion due to deuterium and hydrogen plasma ion exposure. Targets used were a 1.5 μm Cu layer on an aluminum substrate. Cu layer thickness is tracked in real time using 1.2 MeV proton RBS. Measured erosion rates will be compared to results from literature and He erosion rates. Supported by US DoE award DE-SC00-02060.

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.

Effect of sulfuric acid concentration of bentonite and calcination time of pillared bentonite

NASA Astrophysics Data System (ADS)

Mara, Ady; Wijaya, Karna; Trisunaryati, Wega; Mudasir

2016-04-01

An activation of natural clay has been developed. Activation was applied by refluxing the natural bentonite in variation of the sulfuric acid concentration and calcination time of pillared bentonite (PLC). Calcination was applied using oven in microwave 2,45 GHz. Determination of acidity was applied by measuring the amount of adsorbed ammonia and pyridine. Morphological, functional groups and chrystanility characterizations were analyzed using SEM, TEM, FTIR and XRD. Porosity was analyzed using SSA. The results showed that the greater of the concentration of sulfuric acid and calcination time was, the greater the acidity of bentonite as well as the pore diameter were. FTIR spectra showed no fundamental changes in the structure of the natural bentonite, SEM, and TEM images were showing an increase in space or field due to pillarization while the XRD patterns showed a shift to a lower peak. Optimization was obtained at a concentration of 2 M of sulfuric acid and calcination time of 20 minutes, keggin ion of 2.2 and suspension of 10 mmol, respectively each amounted to 11.7490 mmol/gram of ammonia and 2.4437 mmol/gram of pyridine with 154.6391 m2/gram for surface area, 0.130470 m3/gram of pore volume and 3.37484 nm of pore diameter.

Evaluation of continuous 4-day exposure to peracetic acid as a treatment for Ichthyophthirius multifiliis.

PubMed

Sudová, Eliska; Straus, David L; Wienke, Andreas; Meinelt, Thomas

2010-01-01

The parasitic ciliate Ichthyophthirius multifiliis infests all species of freshwater fish and can cause severe economic losses in fish breeding. The most effective treatment, malachite green, has been banned in Europe and North America for use in food fish production. Peracetic acid (PAA) was found to be toxic to I. multifiliis theronts at low concentrations. I. multifiliis-infested carp were exposed to 1 mg/l PAA in a dynamic exposure by means of peristaltic pumps. Five days after infestation, gills, tail fins, and skin below the dorsal fin were observed microscopically for I. multifiliis abundance. After PAA exposure, PAA-treated fish showed lower infestation of I. multifiliis in all investigated tissues than the unexposed control fish. The infestation increased in the control group whereas the infestation in the PAA-exposed groups significantly decreased (p = 0.0083, Bonferroni correction). The fish in the two exposure groups showed a slight reinfestation with I. multifiliis. This might be caused by a peroxide degradation (hydrolysis) and/or reduction of the delivered PAA concentration. Thus, PAA concentrations were possibly too low to be effective on the released trophonts and/or the infective theronts. This hypothesis is corroborated by the fact that the I. multifiliis in the gills, skin, and fins of the PAA-exposed carp were in an early developmental stage.

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.

EFFECTS OF 20 WEEK EXPOSURES IN FEMALE SPRAGUE-DAWLEY (S-D) RATS TO DIBROMOACETIC ACID, A DRINKING WATER DISINFECTANT BY-PRODUCT

EPA Science Inventory

Effects of 20 week exposures in female Sprague-Dawley (S-D) rats to the drinking water disinfection by-product dibromoacetic acid. A S Murr and J M Goldman, Endocrinol. Br., RTD, NHEERL, ORD, US EPA, Res. Tri. Pk, NC. Sponsor: Audrey Cummings

The drinking water disinfect...

EFFECTS OF 20 WEEK EXPOSURES IN FEMALE SPRAGUE-DAWLEY (S-D) RATS TO THE DRINKING WATER DISINFECTION BY-PRODUCT DIBROMOACETIC ACID

EPA Science Inventory

Effects of 20 week exposures in female Sprague-Dawley (S-D) rats to the drinking water disinfection by-product dibromoacetic acid. A S Murr and J M Goldman, Endocrinol. Br., RTD, NHEERL, ORD, US EPA, Res. Tri. Pk, NC. Sponsor: Audrey Cummings

The drinking water disinfect...

High-resolution metabolomics of occupational exposure to trichloroethylene

PubMed Central

Walker, Douglas I; Uppal, Karan; Zhang, Luoping; Vermeulen, Roel; Smith, Martyn; Hu, Wei; Purdue, Mark P; Tang, Xiaojiang; Reiss, Boris; Kim, Sungkyoon; Li, Laiyu; Huang, Hanlin; Pennell, Kurt D; Jones, Dean P; Rothman, Nathaniel; Lan, Qing

2016-01-01

Background: Occupational exposure to trichloroethylene (TCE) has been linked to adverse health outcomes including non-Hodgkin’s lymphoma and kidney and liver cancer; however, TCE’s mode of action for development of these diseases in humans is not well understood. Methods: Non-targeted metabolomics analysis of plasma obtained from 80 TCE-exposed workers [full shift exposure range of 0.4 to 230 parts-per-million of air (ppma)] and 95 matched controls were completed by ultra-high resolution mass spectrometry. Biological response to TCE exposure was determined using a metabolome-wide association study (MWAS) framework, with metabolic changes and plasma TCE metabolites evaluated by dose-response and pathway enrichment. Biological perturbations were then linked to immunological, renal and exposure molecular markers measured in the same population. Results: Metabolic features associated with TCE exposure included known TCE metabolites, unidentifiable chlorinated compounds and endogenous metabolites. Exposure resulted in a systemic response in endogenous metabolism, including disruption in purine catabolism and decreases in sulphur amino acid and bile acid biosynthesis pathways. Metabolite associations with TCE exposure included uric acid (β = 0.13, P-value = 3.6 × 10−5), glutamine (β = 0.08, P-value = 0.0013), cystine (β = 0.75, P-value = 0.0022), methylthioadenosine (β = −1.6, P-value = 0.0043), taurine (β = −2.4, P-value = 0.0011) and chenodeoxycholic acid (β = −1.3, P-value = 0.0039), which are consistent with known toxic effects of TCE, including immunosuppression, hepatotoxicity and nephrotoxicity. Correlation with additional exposure markers and physiological endpoints supported known disease associations. Conclusions: High-resolution metabolomics correlates measured occupational exposure to internal dose and metabolic response, providing insight into molecular mechanisms of exposure

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. Copyright © 2016 Elsevier Ltd. All rights reserved.

Numeral size, spacing between targets, and exposure time in discrimination by elderly people using an lcd monitor.

PubMed

Huang, Kuo-Chen; Yeh, Po-Chan

2007-04-01

The present study investigated the effects of numeral size, spacing between targets, and exposure time on the discrimination performance by elderly and younger people using a liquid crystal display screen. Analysis showed size of numerals significantly affected discrimination, which increased with increasing numeral size. Spacing between targets also had a significant effect on discrimination, i.e., the larger the space between numerals, the better their discrimination. When the spacing between numerals increased to 4 or 5 points, however, discrimination did not increase beyond that for 3-point spacing. Although performance increased with increasing exposure time, the difference in discrimination at an exposure time of 0.8 vs 1.0 sec. was not significant. The accuracy by the elderly group was less than that by younger subjects.

Quantification of Acute Vocal Fold Epithelial Surface Damage with Increasing Time and Magnitude Doses of Vibration Exposure

PubMed Central

Kojima, Tsuyoshi; Van Deusen, Mark; Jerome, W. Gray; Garrett, C. Gaelyn; Sivasankar, M. Preeti; Novaleski, Carolyn K.; Rousseau, Bernard

2014-01-01

Because the vocal folds undergo repeated trauma during continuous cycles of vibration, the epithelium is routinely susceptible to damage during phonation. Excessive and prolonged vibration exposure is considered a significant predisposing factor in the development of vocal fold pathology. The purpose of the present study was to quantify the extent of epithelial surface damage following increased time and magnitude doses of vibration exposure using an in vivo rabbit phonation model. Forty-five New Zealand white breeder rabbits were randomized to nine groups and received varying phonation time-doses (30, 60, or 120 minutes) and magnitude-doses (control, modal intensity phonation, or raised intensity phonation) of vibration exposure. Scanning electron microscopy and transmission electron microscopy was used to quantify the degree of epithelial surface damage. Results revealed a significant reduction in microprojection density, microprojection height, and depth of the epithelial surface with increasing time and phonation magnitudes doses, signifying increased epithelial surface damage risk with excessive and prolonged vibration exposure. Destruction to the epithelial cell surface may provide significant insight into the disruption of cell function following prolonged vibration exposure. One important goal achieved in the present study was the quantification of epithelial surface damage using objective imaging criteria. These data provide an important foundation for future studies of long-term tissue recovery from excessive and prolonged vibration exposure. PMID:24626217

Kinetic Stability of MOF-5 in Humid Environments: Impact of Powder Densification, Humidity Level, and Exposure Time.

PubMed

Ming, Yang; Purewal, Justin; Yang, Jun; Xu, Chunchuan; Soltis, Rick; Warner, James; Veenstra, Mike; Gaab, Manuela; Müller, Ulrich; Siegel, Donald J

2015-05-05

Metal-organic frameworks (MOFs) are an emerging class of microporous, crystalline materials with potential applications in the capture, storage, and separation of gases. Of the many known MOFs, MOF-5 has attracted considerable attention because of its ability to store gaseous fuels at low pressure with high densities. Nevertheless, MOF-5 and several other MOFs exhibit limited stability upon exposure to reactive species such as water. The present study quantifies the impact of humid air exposure on the properties of MOF-5 as a function of exposure time, humidity level, and morphology (i.e., powders vs pellets). Properties examined include hydrogen storage capacity, surface area, and crystallinity. Water adsorption/desorption isotherms are measured using a gravimetric technique; the first uptake exhibits a type V isotherm with a sudden increase in uptake at ∼50% relative humidity. For humidity levels below this threshold only minor degradation is observed for exposure times up to several hours, suggesting that MOF-5 is more stable than generally assumed under moderately humid conditions. In contrast, irreversible degradation occurs in a matter of minutes for exposures above the 50% threshold. Fourier transform infrared spectroscopy indicates that molecular and/or dissociated water is inserted into the skeletal framework after long exposure times. Densification into pellets can slow the degradation of MOF-5 significantly, and may present a pathway to enhance the stability of some MOFs.

Early valproic acid exposure alters functional organization in the primary visual cortex

PubMed Central

Pohl-Guimaraes, Fernanda; Krahe, Thomas E.; Medina, Alexandre E.

2018-01-01

Epilepsy is one of the most common neurologic disorders and affects 0.5 to 1% of pregnant women. The use of antiepileptic drugs, which is usually continued throughout pregnancy, can cause in offspring mild to severe sensory deficits. Neuronal selectivity to stimulus orientation is a basic functional property of the visual cortex that is crucial for perception of shapes and borders. Here we investigate the effects of early exposure to valproic acid (Val) and levetiracetam (Lev), commonly used antiepileptic drugs, on the development of cortical neuron orientation selectivity and organization of cortical orientation columns. Ferrets pups were exposed to Val (200 mg/kg), Lev (100 mg/kg) or saline every other day between postnatal day (P) 10 and P30, a period roughly equivalent to the third trimester of human gestation. Optical imaging of intrinsic signals or single-unit recordings were examined at P42–P84, when orientation selectivity in the ferret cortex has reached a mature state. Optical imaging of intrinsic signals revealed decreased contrast of orientation maps in Val-but not Lev- or saline-treated animals. Moreover, single-unit recordings revealed that early Val treatment also reduced orientation selectivity at the cellular level. These findings indicate that Val exposure during a brief period of development disrupts cortical processing of sensory information at a later age and suggest a neurobiological substrate for some types of sensory deficits in fetal anticonvulsant syndrome. PMID:21215743

Early valproic acid exposure alters functional organization in the primary visual cortex.

PubMed

Pohl-Guimaraes, Fernanda; Krahe, Thomas E; Medina, Alexandre E

2011-03-01

Epilepsy is one of the most common neurologic disorders and affects 0.5 to 1% of pregnant women. The use of antiepileptic drugs, which is usually continued throughout pregnancy, can cause in offspring mild to severe sensory deficits. Neuronal selectivity to stimulus orientation is a basic functional property of the visual cortex that is crucial for perception of shapes and borders. Here we investigate the effects of early exposure to valproic acid (Val) and levetiracetam (Lev), commonly used antiepileptic drugs, on the development of cortical neuron orientation selectivity and organization of cortical orientation columns. Ferrets pups were exposed to Val (200mg/kg), Lev (100mg/kg) or saline every other day between postnatal day (P) 10 and P30, a period roughly equivalent to the third trimester of human gestation. Optical imaging of intrinsic signals or single-unit recordings were examined at P42-P84, when orientation selectivity in the ferret cortex has reached a mature state. Optical imaging of intrinsic signals revealed decreased contrast of orientation maps in Val- but not Lev- or saline-treated animals. Moreover, single-unit recordings revealed that early Val treatment also reduced orientation selectivity at the cellular level. These findings indicate that Val exposure during a brief period of development disrupts cortical processing of sensory information at a later age and suggest a neurobiological substrate for some types of sensory deficits in fetal anticonvulsant syndrome. Copyright © 2011 Elsevier Inc. All rights reserved.

Electromagnetic navigation reduces surgical time and radiation exposure for proximal interlocking in retrograde femoral nailing.

PubMed

Somerson, Jeremy S; Rowley, David; Kennedy, Chad; Buttacavoli, Frank; Agarwal, Animesh

2014-07-01

To compare the time required for proximal locking screw placement between a standard freehand technique and the navigated technique, and to quantify the reduction in ionizing radiation exposure. A fresh frozen cadaver model was used for 48 proximal interlocking screw procedures. Each procedure consisted of insertion of 2 anteroposterior locking screws. Standard fluoroscopic technique was used for 24 procedures, and an electromagnetic navigation system was used for the remaining 24 procedures. Procedure duration was recorded using an electronic timer and radiation doses were documented. Mean total insertion time for both proximal interlocking screws was 405 ± 165.7 seconds with the freehand technique and 311 ± 78.3 seconds in the navigation group (P = 0.002). All procedures resulted in successful locking screw placement. Mean ionizing radiation exposure time for proximal locking was 29.5 ± 12.8 seconds. Proximal locking screw insertion using the navigation technique evaluated in this work was significantly faster than the standard fluoroscopic method. The navigated technique is effective and has the potential to prevent ionizing radiation exposure.

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.

Determination of methyl-, 2-hydroxyethyl- and 2-cyanoethylmercapturic acids as biomarkers of exposure to alkylating agents in cigarette smoke.

PubMed

Scherer, Gerhard; Urban, Michael; Hagedorn, Heinz-Werner; Serafin, Richard; Feng, Shixia; Kapur, Sunil; Muhammad, Raheema; Jin, Yan; Sarkar, Mohamadi; Roethig, Hans-Juergen

2010-10-01

Alkylating agents occur in the environment and are formed endogenously. Tobacco smoke contains a variety of alkylating agents or precursors including, among others, N-nitrosodimethylamine (NDMA), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), acrylonitrile and ethylene oxide. We developed and validated a method for the simultaneous determination of methylmercapturic acid (MMA, biomarker for methylating agents such as NDMA and NNK), 2-hydroxyethylmercapturic acid (HEMA, biomarker for ethylene oxide) and 2-cyanoethylmercapturic acid (CEMA, biomarker for acrylonitrile) in human urine using deuterated internal standards of each compound. The method involves liquid/liquid extraction of the urine sample, solid phase extraction on anion exchange cartridges, derivatization with pentafluorobenzyl bromide (PFBBr), liquid/liquid extraction of the reaction mixture and LC-MS/MS analysis with positive electrospray ionization. The method was linear in the ranges of 5.00-600, 1.00-50.0 and 1.50-900 ng/ml for MMA, HEMA and CEMA, respectively. The method was applied to two clinical studies in adult smokers of conventional cigarettes who either continued smoking conventional cigarettes, were switched to test cigarettes consisting of either an electrically heated cigarette smoking system (EHCSS) or having a highly activated carbon granule filter that were shown to have reduced exposure to specific smoke constituents, or stopped smoking. Urinary excretion of MMA was found to be unaffected by switching to the test cigarettes or stop smoking. Urinary HEMA excretion decreased by 46 to 54% after switching to test cigarettes and by approximately 74% when stopping smoking. Urinary CEMA excretion decreased by 74-77% when switching to test cigarettes and by approximately 90% when stopping smoking. This validated method for urinary alkylmercapturic acids is suitable to distinguish differences in exposure not only between smokers and nonsmokers but also between smoking of conventional and

Microwave-Assisted Rapid Enzymatic Synthesis of Nucleic Acids.

PubMed

Hari Das, Rakha; Ahirwar, Rajesh; Kumar, Saroj; Nahar, Pradip

2016-07-02

Herein we report microwave-induced enhancement of the reactions catalyzed by Escherichia coli DNA polymerase I and avian myeloblastosis virus-reverse transcriptase. The reactions induced by microwaves result in a highly selective synthesis of nucleic acids in 10-50 seconds. In contrast, same reactions failed to give desired reaction products when carried out in the same time periods, but without microwave irradiation. Each of the reactions was carried out for different duration of microwave exposure time to find the optimum reaction time. The products produced by the respective enzyme upon microwave irradiation of the reaction mixtures were identical to that produced by the conventional procedures. As the microwave-assisted reactions are rapid, microwave could be a useful alternative to the conventional and time consuming procedures of enzymatic synthesis of nucleic acids.

Residential exposure to traffic noise and leisure-time sports - A population-based study.

PubMed

Roswall, Nina; Ammitzbøll, Gunn; Christensen, Jeppe Schultz; Raaschou-Nielsen, Ole; Jensen, Steen Solvang; Tjønneland, Anne; Sørensen, Mette

2017-08-01

Traffic levels have been found a significant environmental predictor for physical inactivity. A recent study suggested that traffic noise annoyance was associated with lower physical activity. We investigated associations between modelled residential traffic noise and leisure-time sports. In the Diet, Cancer and Health cohort, we performed cross-sectional analyses using data from the baseline questionnaire (1993-97), and longitudinal analyses of change between baseline and follow-up (2000-02). People reported participation (yes/no) and hours of leisure-time sport, from which we calculated MET hrs/week. Present and historical addresses from 1987 to 2002 were found in national registries, and traffic noise was modelled 1 and 5 years before enrolment, and from baseline to follow-up. Analyses were performed using logistic and linear regression. Traffic noise exposure 5 years before baseline was associated with higher prevalence odds ratio of non-participation in leisure-time sports; significantly for road traffic noise (odds ratio (OR): 1.10; 95% confidence interval (CI): 1.07-1.13) and borderline for railway noise (OR: 1.03; 95% CI: 0.99-1.07), per 10dB. In longitudinal analyses, a 10dB higher road traffic noise was associated with a higher prevalence odds ratio of ceasing (OR: 1.12; 95% CI: 1.07-1.18) and a lower prevalence odds ratio of initiating (OR: 0.92; 95% CI: 0.87-0.96) leisure-time sports. Exposure to railway noise was negatively associated with baseline MET hrs/week, whereas no association was found in longitudinal analyses, or for road traffic noise. The study suggests that long-term exposure to residential road traffic noise is negatively associated with leisure-time sports. Results for railway noise were less consistent. Copyright © 2017 Elsevier GmbH. All rights reserved.

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. Copyright © 2015 Elsevier Inc. All rights reserved.

Exposure of tumor-bearing mice to extremely high-frequency electromagnetic radiation modifies the composition of fatty acids in thymocytes and tumor tissue.

PubMed

Gapeyev, Andrew B; Kulagina, Tatiana P; Aripovsky, Alexander V

2013-08-01

To test the participation of fatty acids (FA) in antitumor effects of extremely high-frequency electromagnetic radiation (EHF EMR), the changes in the FA composition in the thymus, liver, blood plasma, muscle tissue, and tumor tissue in mice with Ehrlich solid carcinoma exposed to EHF EMR were studied. Normal and tumor-bearing mice were exposed to EHF EMR with effective parameters (42.2 GHz, 0.1 mW/cm2, 20 min daily during five consecutive days beginning the first day after the inoculation of tumor cells). Fatty acid composition of various organs and tissues of mice were determined using a gas chromatography. It was shown that the exposure of normal mice to EHF EMR or tumor growth significantly increased the content of monounsaturated FA (MUFA) and decreased the content of polyunsaturated FA (PUFA) in all tissues examined. Exposure of tumor-bearing mice to EHF EMR led to the recovery of FA composition in thymocytes to the state that is typical for normal animals. In other tissues of tumor-bearing mice, the exposure to EHF EMR did not induce considerable changes that would be significantly distinguished between disturbances caused by EHF EMR exposure or tumor growth separately. In tumor tissue which is characterized by elevated level of MUFA, the exposure to EHF EMR significantly decreased the summary content of MUFA and increased the summary content of PUFA. The recovery of the FA composition in thymocytes and the modification of the FA composition in the tumor under the influence of EHF EMR on tumor-bearing animals may have crucial importance for elucidating the mechanisms of antitumor effects of the electromagnetic radiation.

Concentration and time-dependent effect of initial sodium hypochlorite on the ability of QMix and ethylenediaminetetraacetic acid to remove smear layer.

PubMed

Aksel, Hacer; Serper, Ahmet

2017-01-01

The aim of this study was to compare the ability of 17% ethylenediaminetetraacetic acid (EDTA) and QMix with different concentrations and time exposures of initial sodium hypochlorite (NaOCl) to remove the smear layer from the root canals. Eighty maxillary central incisors were used. After instrumentation, the teeth were divided into eight experimental groups according to the initial and final rinse. About 2.5% and 5% NaOCl were used during instrumentation and for 1 or 3 min was used as postinstrumentation initial irrigants, and 17% EDTA and QMix used as final irrigants. The apical and middle parts of the specimens were observed by scanning electron microscope. Data were analyzed using the Kruskal-Wallis, Mann-Whitney, and Friedman's test. Regardless of the type of final irrigant, QMix allowed more smear layer removal than EDTA after using 5% initial NaOCl for 3 min. In the apical part of the root canal walls, the smear layer was not completely removed. QMix and EDTA were similarly effective in smear layer removal at the middle parts of the root canal regardless of the concentration and time exposure of initial NaOCl, while none of the irrigation protocols was able to remove smear layer at the apical parts.

Timing and Duration of Traffic-related Air Pollution Exposure and the Risk for Childhood Wheeze and Asthma.

PubMed

Brunst, Kelly J; Ryan, Patrick H; Brokamp, Cole; Bernstein, David; Reponen, Tiina; Lockey, James; Khurana Hershey, Gurjit K; Levin, Linda; Grinshpun, Sergey A; LeMasters, Grace

2015-08-15

The timing and duration of traffic-related air pollution (TRAP) exposure may be important for childhood wheezing and asthma development. We examined the relationship between TRAP exposure and longitudinal wheezing phenotypes and asthma at age 7 years. 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. 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). 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.

Duration of time on shift before accidental blood or body fluid exposure for housestaff, nurses, and technicians.

PubMed

Green-McKenzie, Judith; Shofer, Frances S

2007-01-01

Shift work has been found to be associated with an increased rate of errors and accidents among healthcare workers (HCWs), but the effect of shift work on accidental blood and body fluid exposure sustained by HCWs has not been well characterized. To determine the duration of time on shift before accidental blood and body fluid exposure in housestaff, nurses, and technicians and the proportion of housestaff who sustain a blood and body fluid exposure after 12 hours on duty. This retrospective, descriptive study was conducted during a 24-month period at a large urban teaching hospital. Participants were HCWs who sustained an accidental blood and body fluid exposure. Housestaff were on duty significantly longer than both nursing staff (P=.02) and technicians (P<.0001) before accidental blood and body fluid exposure. Half of the blood and body fluid exposures sustained by housestaff occurred after being on duty 8 hours or more, and 24% were sustained after being on duty 12 hours or more. Of all HCWs, 3% reported an accidental blood and body fluid exposure, with specific rates of 7.9% among nurses, 9.4% among housestaff, and 3% among phlebotomists. Housestaff were significantly more likely to have longer duration of time on shift before blood and body fluid exposure than were the other groups. Almost one-quarter of accidental blood and body fluid exposures to housestaff were incurred after they had been on duty for 12 hours or more. Housestaff sustained a higher rate of accidental blood and body fluid exposures than did nursing staff and technicians.

Prediction of Bacillus weihenstephanensis acid resistance: the use of gene expression patterns to select potential biomarkers.

PubMed

Desriac, N; Postollec, F; Coroller, L; Sohier, D; Abee, T; den Besten, H M W

2013-10-01

Exposure to mild stress conditions can activate stress adaptation mechanisms and provide cross-resistance towards otherwise lethal stresses. In this study, an approach was followed to select molecular biomarkers (quantitative gene expressions) to predict induced acid resistance after exposure to various mild stresses, i.e. exposure to sublethal concentrations of salt, acid and hydrogen peroxide during 5 min to 60 min. Gene expression patterns of unstressed and mildly stressed cells of Bacillus weihenstephanensis were correlated to their acid resistance (3D value) which was estimated after exposure to lethal acid conditions. Among the twenty-nine candidate biomarkers, 12 genes showed expression patterns that were correlated either linearly or non-linearly to acid resistance, while for the 17 other genes the correlation remains to be determined. The selected genes represented two types of biomarkers, (i) four direct biomarker genes (lexA, spxA, narL, bkdR) for which expression patterns upon mild stress treatment were linearly correlated to induced acid resistance; and (ii) nine long-acting biomarker genes (spxA, BcerKBAB4_0325, katA, trxB, codY, lacI, BcerKBAB4_1716, BcerKBAB4_2108, relA) which were transiently up-regulated during mild stress exposure and correlated to increased acid resistance over time. Our results highlight that mild stress induced transcripts can be linearly or non-linearly correlated to induced acid resistance and both approaches can be used to find relevant biomarkers. This quantitative and systematic approach opens avenues to select cellular biomarkers that could be incremented in mathematical models to predict microbial behaviour. Copyright © 2013 Elsevier B.V. All rights reserved.

TWENTY WEEK EXPOSURES TO THE DRINKING WATER DISINFECTION BY-PRODUCT DIBROMOACETIC ACID: REPRODUCTIVE CYCLICITY AND STEROID CONCENTRATIONS IN THE FEMALE SPRAGUE-DAWLEY RAT

EPA Science Inventory

Abstract
Elevated gavage exposures to the drinking water disinfection by-product dibromoacetic acid (DBA) have been found to disrupt estrous cyclicity in the rat and induce increases in estradiol concentrations in both cycling (day of estrus) and ovariectomized/estradiol-impla...

Defining pollen exposure times for clinical trials of allergen immunotherapy for pollen-induced rhinoconjunctivitis - an EAACI position paper.

PubMed

Pfaar, O; Bastl, K; Berger, U; Buters, J; Calderon, M A; Clot, B; Darsow, U; Demoly, P; Durham, S R; Galán, C; Gehrig, R; Gerth van Wijk, R; Jacobsen, L; Klimek, L; Sofiev, M; Thibaudon, M; Bergmann, K C

2017-05-01

Clinical efficacy of pollen allergen immunotherapy (AIT) has been broadly documented in randomized controlled trials. The underlying clinical endpoints are analysed in seasonal time periods predefined based on the background pollen concentration. However, any validated or generally accepted definition from academia or regulatory authorities for this relevant pollen exposure intensity or period of time (season) is currently not available. Therefore, this Task Force initiative of the European Academy of Allergy and Clinical Immunology (EAACI) aimed to propose definitions based on expert consensus. A Task Force of the Immunotherapy and Aerobiology and Pollution Interest Groups of the EAACI reviewed the literature on pollen exposure in the context of defining relevant time intervals for evaluation of efficacy in AIT trials. Underlying principles in measuring pollen exposure and associated methodological problems and limitations were considered to achieve a consensus. The Task Force achieved a comprehensive position in defining pollen exposure times for different pollen types. Definitions are presented for 'pollen season', 'high pollen season' (or 'peak pollen period') and 'high pollen days'. This EAACI position paper provides definitions of pollen exposures for different pollen types for use in AIT trials. Their validity as standards remains to be tested in future studies. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

EFFECT OF GESTATIONAL EXPOSURE TO ETHANE DIMETHANESULFONATE (EDS), BROMOCHLOROACETIC ACID (BCA) AND MOLINATE ON REPRODUCTIVE FUNCTION IN CD-1 MALE MICE

EPA Science Inventory

EFFECT OF GESTATIONAL EXPOSURE TO ETHANE DIMETHANESULFONATE (EDS), BROMOCHLOROACETIC ACID (BCA) AND MOLINATE ON REPRODUCTIVE FUNCTION IN CD-1 MALE MICE. D.K. Tarka1,2 , G.R. Klinefelter2, J.C. Rockett2, J.D. Suarez2, N.L. Roberts2 and J.M. Rogers1,2. 1 University of North Carol...

Time-dependent changes in the plasma amino acid concentration in diabetes mellitus.

PubMed

Mochida, Taiga; Tanaka, Takayuki; Shiraki, Yasuko; Tajiri, Hiroko; Matsumoto, Shirou; Shimbo, Kazutaka; Ando, Toshihiko; Nakamura, Kimitoshi; Okamoto, Masahiro; Endo, Fumio

2011-08-01

We investigated longitudinal change in the amino acid (AA) profile in type 1 diabetes mellitus (DM) using AKITA mice, which develop DM as a result of insulin deficiency. The plasma concentrations of valine, leucine, isoleucine, as well as the total branched chain amino acids, alanine, citrulline and proline, were significantly higher in the diabetic mice. We show that the degree and timing of the changes were different among the plasma amino acid concentrations (pAAs) during the development of type 1 DM. Copyright © 2011 Elsevier Inc. All rights reserved.

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