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1.  Realities of environmental toxicity and their ramifications for community engagement 
Research on community responses to environmental toxicity has richly described the struggles of citizens to identify unrecognized toxins, collect their own environmental health facts, and use them to lobby authorities for recognition and remediation. Much of this literature is based on an empiricist premise: it is concerned with exploring differences in how laypeople and experts perceive what is presumed to be a singular toxic reality that preexists these varying perspectives. Here, we seek to reexamine this topic by shifting the focus from facts to facticity—that is, by exploring the many types of knowledge that communities develop about toxicity and how these knowledges articulate with the ideas of scientific and governmental authorities about what kinds of information are valid bases for policymaking. In making this shift, we are influenced by work in semiotic anthropology and science and technology studies (STS), which emphasizes that lived experience generates distinct realities rather than different perceptions of the same underlying state. Using this framework, we present an analysis of oral history interviews conducted in 2013–14 in the small American town of Ambler, Pennsylvania. Part of Ambler’s legacy as a nineteenth- and twentieth-century center of asbestos manufacture is that it is home to two massive asbestos-containing waste sites, one of which was being remediated by the Environmental Protection Agency (EPA) at the time of this study. Our interviews demonstrate that even asbestos, a toxin with a well-established public narrative, is a fundamentally different object for different members of the Ambler community. For many of these individuals, the epistemology and practices of the EPA are incongruent with or tangential to their toxicity-related experiences and their consequent concerns for the future. As such, our findings suggest caution in framing the community engagement efforts of environmental health agencies primarily as facilitations of citizen science; this approach does not acknowledge the multiplicity of toxic realities.
PMCID: PMC5107345  PMID: 27783970
USA; environmental toxicity; risk; community engagement; citizen science; semiotic anthropology; ontological turn; asbestos
2.  Low-temperature dynamic nuclear polarization of gases in frozen mixtures 
Magnetic resonance in medicine  2015;76(3):1007-1014.
To present a new cryogenic technique for preparing gaseous compounds in solid mixtures for polarization using dynamic nuclear polarization (DNP).
129Xe and 15N2O samples were prepared using the presented method. Samples were hyperpolarized at 1.42K at 5T. 129Xe was polarized at 1.65K and 1.42K to compare enhancement. Polarization levels for both samples and T1 relaxation times for the 129Xe sample were measured. Sample pulverization for the 129Xe and controlled annealing for both samples were introduced as additional steps in sample preparation.
Enhancement increased by 15% due to a temperature drop from 1.65K to 1.42K for the 129Xe sample. A polarization level of 20±3% for the 129Xe sample was achieved, a 2-fold increase from 10±1% after pulverization of the sample at 1.42K. T1 of the 129Xe sample was increased by more than 3-fold via annealing. In the case of 15N2O, annealing led to a ~2-fold increase in the signal level after DNP.
The presented technique for producing and manipulating solid gas/glassing agent/radical mixtures for DNP led to high polarization levels in 129Xe and 15N2O samples. These methods show potential for polarizing other gases using DNP technology.
PMCID: PMC4824673  PMID: 26444315
Hyperpolarization; Dynamic Nuclear Polarization; Gas MRI; Sample Preparation
3.  Regional Fractional Ventilation by Using Multibreath Wash-in 3He MR Imaging 
Radiology  2016;279(3):917-924.
This study demonstrates the feasibility of a multibreath wash-in hyperpolarized helium 3 MR imaging approach to ventilation imaging in human subjects; in doing so, it reveals ventilation differences between patients with chronic obstructive pulmonary disease and healthy subjects and corrects several sources of potential bias in ventilation measurements.
To assess the feasibility and optimize the accuracy of the multibreath wash-in hyperpolarized helium 3 (3He) approach to ventilation measurement by using magnetic resonance (MR) imaging as well as to examine the physiologic differences that this approach reveals among nonsmokers, asymptomatic smokers, and patients with chronic obstructive pulmonary disease (COPD).
Materials and Methods
All experiments were approved by the local institutional review board and compliant with HIPAA. Informed consent was obtained from all subjects. To measure fractional ventilation, the authors administered a series of identical normoxic hyperpolarized gas breaths to the subject; after each inspiration, an image was acquired during a short breath hold. Signal intensity buildup was fit to a recursive model that regionally solves for fractional ventilation. This measurement was successfully performed in nine subjects: three healthy nonsmokers (one man, two women; mean age, 45 years ± 4), three asymptomatic smokers (three men; mean age, 51 years ± 5), and three patients with COPD (three men; mean age, 59 years ± 5). Repeated measures analysis of variance was performed, followed by post hoc tests with Bonferroni correction, to assess the differences among the three cohorts.
Whole-lung fractional ventilation as measured with hyperpolarized 3He in all subjects (mean, 0.24 ± 0.06) showed a strong correlation with global fractional ventilation as measured with a gas delivery device (R2 = 0.96, P < .001). Significant differences between the means of whole-lung fractional ventilation (F2,10 = 7.144, P = .012) and fractional ventilation heterogeneity (F2,10 = 7.639, P = .010) were detected among cohorts. In patients with COPD, the protocol revealed regions wherein fractional ventilation varied substantially over multiple breaths.
Multibreath wash-in hyperpolarized 3He MR imaging of fractional ventilation is feasible in human subjects and demonstrates very good global (whole-lung) precision. Fractional ventilation measurement with this physiologically realistic approach reveals significant differences between patients with COPD and healthy subjects. To minimize error, several sources of potential bias must be corrected when calculating fractional ventilation.
© RSNA, 2016
Online supplemental material is available for this article.
PMCID: PMC4886701  PMID: 26785042
4.  Visualizing the Propagation of Acute Lung Injury 
Anesthesiology  2016;124(1):121-131.
Mechanical ventilation worsens acute respiratory distress syndrome (ARDS), but this secondary ‘ventilator-associated’ injury is variable and difficult to predict. We aimed to visualize the propagation of such ventilator-induced injury, in the presence (and absence) of a primary underlying lung injury, and to determine the predictors of propagation.
Anesthetized rats (n=20) received acid aspiration (HCl) followed by ventilation with moderate tidal volume (VT). In animals surviving ventilation for at least two hours, propagation of injury was quantified using serial computed tomography (CT). Baseline lung status was assessed by oxygenation, lung weight, and lung strain (VT/expiratory lung volume). Separate groups of rats without HCl aspiration were ventilated with large (n=10) or moderate (n=6) VT.
In 15 rats surviving longer than two hours, CT opacities spread outwards from the initial site of injury. Propagation was associated with higher baseline strain (propagation vs. no propagation, mean ± SD: 1.52 ± 0.13 vs. 1.16 ± 0.20, p<0.01), but similar oxygenation and lung weight. Propagation did not occur where baseline strain <1.29. In healthy animals, large VT caused injury that was propagated inwards from the lung periphery; in the absence of preexisting injury, propagation did not occur where strain was <2.0.
Compared with healthy lungs, underlying injury causes propagation to occur at a lower strain threshold and, it originates at the site of injury; this suggests that tissue around the primary lesion is more sensitive. Understanding how injury is propagated may ultimately facilitate a more individualized monitoring or management.
PMCID: PMC4681653  PMID: 26536308
5.  Oxygen-weighted Hyperpolarized 3He MR Imaging: A Short-term Reproducibility Study in Human Subjects 
Radiology  2015;277(1):247-258.
The results of this study showed that hyperpolarized helium 3 MR imaging to measure alveolar partial pressure of oxygen is a technique with repeatable results that reveal physiologic differences between nonsmokers and asymptomatic smokers.
To determine whether hyperpolarized helium 3 magnetic resonance (MR) imaging to measure alveolar partial pressure of oxygen (Pao2) shows sufficient test-retest repeatability and between-cohort differences to be used as a reliable technique for detection of alterations in gas exchange in asymptomatic smokers.
Materials and Methods
The protocol was approved by the local institutional review board and was HIPAA compliant. Informed consent was obtained from all subjects. Two sets of MR images were obtained 10 minutes apart in 25 subjects: 10 nonsmokers (five men, five women; mean ± standard deviation age, 50 years ± 6) and 15 smokers (seven women, eight men; mean age, 50 years ± 8). A mixed-effects model was developed to identify the regional repeatability of Pao2 measurements as an intraclass correlation coefficient. Ten smokers were matched with the 10 nonsmokers on the basis of signal-to-noise ratio (SNR). Three separate models were generated: one for nonsmokers, one for the SNR-matched smokers, and one for the five remaining smokers, who were imaged with a significantly higher SNR.
Short-term back-to-back regional reproducibility was assessed by using intraclass correlation coefficients, which were 0.67 and 0.65 for SNR case-matched nonsmokers and smokers, respectively. Repeatability was a strong function of SNR; a 50% increase in SNR in the remaining smokers improved the intraclass correlation coefficient to 0.82. Although repeatability was not significantly different between the SNR-matched cohorts (P = .44), the smoker group showed higher spatial and temporal variability in Pao2.
The short-term test-retest repeatability of hyperpolarized gas MR imaging of regional Pao2 was good. Asymptomatic smokers exhibited greater spatial and temporal variability in Pao2 than did the nonsmokers, which suggests that this parameter allows detection of small functional alterations associated with smoking.
© RSNA, 2015
Online supplemental material is available for this article.
PMCID: PMC4613882  PMID: 26110668
6.  Hyperpolarized Gas Diffusion MRI for the Study of Atelectasis and Acute Respiratory Distress Syndrome 
NMR in biomedicine  2014;27(12):1468-1478.
Considerable uncertainty remains about the best ventilator strategies for the mitigation of atelectasis and associated airspace stretch in patients with acute respiratory distress syndrome (ARDS). In addition to several immediate physiological effects, atelectasis increases the risk of ventilator-associated lung injury (VALI), which has been shown to significantly worsen ARDS outcomes. A number of lung imaging techniques have made substantial headway in clarifying the mechanisms of atelectasis. This paper reviews the contributions of CT, PET, and conventional MRI to understanding this phenomenon. In doing so, it also reveals several important shortcomings inherent to each of these approaches. Once these shortcomings have been made apparent, we describe how hyperpolarized gas magnetic resonance imaging (HP MRI)—a technique that is uniquely able to assess responses to mechanical ventilation and lung injury in peripheral airspaces—is poised to fill several of these knowledge gaps. The HP-MRI-derived apparent diffusion coefficient (ADC) quantifies the restriction of 3He diffusion by peripheral airspaces, thereby obtaining pulmonary structural information at an extremely small scale. Lastly, this paper reports the results of a series of experiments that measured ADC in mechanically ventilated rats in order to investigate (i) the effect of atelectasis on ventilated airspaces; (ii) the relationship between positive end-expiratory pressure (PEEP), hysteresis, and the dimensions of peripheral airspaces; and (iii) the ability of PEEP and surfactant to reduce airspace dimensions after lung injury. An increase in ADC was found to be a marker of atelectasis-induced overdistension. With recruitment, higher airway pressures were shown to reduce stretch rather than worsen it. Moving forward, HP MRI has significant potential to shed further light on the atelectatic processes that occur during mechanical ventilation.
PMCID: PMC4232982  PMID: 24920074
ventilator-induced lung injury; alveolar recruitment; artificial respiration; magnetic resonance imaging; hyperpolarized gas; atelectasis
7.  Out smoking on the big screen: Tobacco use in LGBT movies, 2000–2011 
Tobacco control  2013;23(0):e156-e158.
Lesbian, gay, bisexual, and transgender (LGBT) people have significantly higher smoking prevalence than heterosexual people in the United States. The reasons for this disparity remain unclear. Tobacco use in movies has a substantial influence on tobacco use behaviours, particularly among youth. Yet, no research has examined tobacco use in movies for LGBT audiences or containing LGBT characters.
We identified 81 U.S. movies from 2000–2011 with a theatre release and with LGBT themes or characters. We then selected a random sample of these movies (n = 45) for quantitative content analysis to examine the proportion of movies with depictions of tobacco use and the number of occurrences of tobacco use.
Tobacco use was depicted in 87%(95% confidence interval [CI]: 80%–94%) of movies with an average of 4 occurrences of tobacco use per hour (95% CI: 3–5). Only 15% (95% CI: 8%–23%) of movies and 3% of all depictions of tobacco use conveyed any harms of tobacco use.
Viewers of movies with LGBT themes or characters are exposed, on average, to one depiction of tobacco use for every 15 minutes of movie run-time. As a major component of the entertainment media environment, movies may contribute to smoking among LGBT people.
PMCID: PMC4032800  PMID: 24277775
tobacco use dependence; smoking; motion pictures as topic; homosexuality; communications media
8.  Evaluating distributional shifts in home range estimates 
Ecology and Evolution  2015;5(18):3869-3878.
A variety of methods are commonly used to quantify animal home ranges using location data acquired with telemetry. High‐volume location data from global positioning system (GPS) technology provide researchers the opportunity to identify various intensities of use within home ranges, typically quantified through utilization distributions (UDs). However, the wide range of variability evident within UDs constructed with modern home range estimators is often overlooked or ignored during home range comparisons, and challenges may arise when summarizing distributional shifts among multiple UDs. We describe an approach to gain additional insight into home range changes by comparing UDs across isopleths and summarizing comparisons into meaningful results. To demonstrate the efficacy of this approach, we used GPS location data from 16 bighorn sheep (Ovis canadensis) to identify distributional changes before and after habitat alterations, and we discuss advantages in its application when comparing home range size, overlap, and joint‐space use. We found a consistent increase in bighorn sheep home range size when measured across home range levels, but that home range overlap and similarity values decreased when examined at increasing core levels. Our results highlight the benefit of conducting multiscale assessments when comparing distributions, and we encourage researchers to expand comparative home range analyses to gain a more comprehensive evaluation of distributional changes and to evaluate comparisons across home range levels.
PMCID: PMC4588651  PMID: 26445648
Brownian bridge; global positioning system; home range comparisons; isopleth; Ovis canadensis; utilization distribution
9.  Diversity of Nitrile Hydratase and Amidase Enzyme Genes in Rhodococcus erythropolis Recovered from Geographically Distinct Habitats 
Applied and Environmental Microbiology  2003;69(10):5754-5766.
A molecular screening approach was developed in order to amplify the genomic region that codes for the α- and β-subunits of the nitrile hydratase (NHase) enzyme in rhodococci. Specific PCR primers were designed for the NHase genes from a collection of nitrile-degrading actinomycetes, but amplification was successful only with strains identified as Rhodococcus erythropolis. A hydratase PCR product was also obtained from R. erythropolis DSM 43066T, which did not grow on nitriles. Southern hybridization of other members of the nitrile-degrading bacterial collection resulted in no positive signals other than those for the R. erythropolis strains used as positive controls. PCR-restriction fragment length polymorphism-single-strand conformational polymorphism (PRS) analysis of the hydratases in the R. erythropolis strains revealed unique patterns that mostly correlated with distinct geographical sites of origin. Representative NHases were sequenced, and they exhibited more than 92.4% similarity to previously described NHases. The phylogenetic analysis and deduced amino acid sequences suggested that the novel R. erythropolis enzymes belonged to the iron-type NHase family. Some different residues in the translated sequences were located near the residues involved in the stabilization of the NHase active site, suggesting that the substitutions could be responsible for the different enzyme activities and substrate specificities observed previously in this group of actinomycetes. A similar molecular screening analysis of the amidase gene was performed, and a correlation between the PRS patterns and the geographical origins identical to the correlation found for the NHase gene was obtained, suggesting that there was coevolution of the two enzymes in R. erythropolis. Our findings indicate that the NHase and amidase genes present in geographically distinct R. erythropolis strains are not globally mixed.
PMCID: PMC201182  PMID: 14532022

Results 1-9 (9)