Inactivation of Bacillus anthracis spores to decontaminate subway railcar and related materials via the fogging of peracetic acid and hydrogen peroxide sporicidal liquids.

The inactivation of Bacillus anthracis spores on subway and used subway railcar materials was evaluated using fogged peracetic acid/hydrogen peroxide (PAA) and hydrogen peroxide (H2O2). A total of 21 separate decontamination tests were conducted using bacterial spores of both B. anthracis Ames (B.a.) and Bacillus atrophaeus (B.g.) inoculated onto several types of materials. Tests were conducted using commercial off-the-shelf fogging equipment filled with either PAA or H2O2 to fumigate a ∼15 cubic meter chamber under uncontrolled ambient relative humidity and controlled temperature (10 or 20 °C) from 8 to 168 h. For the present study, no conditions were found that resulted in complete inactivation of either B.a. Ames or B.g. on all test materials. Approximately 41% and 38% of the decontamination efficacies for B.a. and B.g., respectively, exhibited ≥6 log10 reduction (LR); efficacy depended greatly on the material. When testing at 10 °C, the mean LR was consistently lower for both B.a. and B.g. as compared to 20 °C. Based on the statistical comparison of the LR results, B.g. exhibited equivalent or greater resistance than B.a. for approximately 92% of the time across all 21 tests. The efficacy data suggest that B.g. may be a suitable surrogate for B.a. Ames when assessing the decontamination efficacy of fogged PAA or H2O2. Moreover, the results of this testing indicate that in the event of B.a. spore release into a subway system, the fogging of PAA or H2O2 represents a decontamination option for consideration.

Chikungunya virus infection in Cynomolgus macaques following Intradermal and aerosol exposure.

BACKGROUND: Chikungunya virus (CHIKV) is transmitted via mosquito bite and potentially by aerosol, causing chikungunya fever and arthritic disease in humans. There are currently no licensed vaccines or antiviral therapeutics to protect against CHIKV infection in humans. Animal models recapitulating human disease, especially for transmission by aerosol, are needed for licensure of such medical countermeasures. METHODS: Cynomolgus macaques (CMs) were challenged by intradermal (ID) inoculation or exposure to an aerosol containing CHIKV Ross strain at different target infectious doses (103-107 plaque forming units (PFU)). The clinical and virologic courses of disease were monitored up to 14 days post-exposure. RESULTS: ID infection of CMs led to overt clinical disease, detectable viremia, and increased blood markers of liver damage. Animals challenged by aerosol exhibited viremia and increased liver damage biomarkers with minimal observed clinical disease. All animals survived CHIKV challenge. CONCLUSIONS: We have described CHIKV infection in CMs following ID inoculation and, for the first time, infection by aerosol. Based on limited reported cases in the published literature, the aerosol model recapitulates the virologic findings of human infection via this route. The results of this study provide additional evidence for the potential use of CMs as a model for evaluating medical countermeasures against CHIKV.

(18)F-FDG PET/CT-positive internal mammary lymph nodes: pathologic correlation by ultrasound-guided fine-needle aspiration and assessment of associated risk factors.

OBJECTIVE: Metastatic breast cancer in internal mammary (IM) lymph nodes is associated with a poor prognosis. This study correlates (18)F-FDG PET/CT-positive IM lymph nodes with ultrasound-guided fine-needle aspiration (FNA) cytopathologic results and determines risk factors for IM node positivity on PET/CT. MATERIALS AND METHODS: For this retrospective study, a database search was performed to identify patients referred for whole-body (18)F-FDG PET/CT for initial staging or restaging of breast cancer from January 1, 2005, through December 31, 2010. The radiology reports and images were reviewed for patients with (18)F-FDG-avid IM lymph nodes on PET/ CT and correlated with the cytopathologic results from FNA of selected PET/CT-positive IM lymph nodes. The patients with positive IM nodes on PET/CT who underwent PET/CT for initial staging were compared against age-matched and tumor size-matched patients to identify risk factors for IM node positivity on PET/CT. RESULTS: One hundred ten of 1259 patients (9%) had an (18)F-FDG-avid IM lymph node on PET/CT. Twenty-five patients underwent ultrasound-guided FNA of a suspicious IM node, and 20 IM lymph nodes (80%) were cytologically proven metastases from the primary breast malignancy. High tumor grade, the presence of lymphovascular invasion (LVI), and triple receptor-negative hormonal receptor status were found to be significant risk factors for IM node positivity on PET/CT (p < 0.05). CONCLUSION: Although fewer than 10% of breast cancer patients have positive IM nodes on (18)F-FDG PET/CT performed for initial staging or restaging, a positive IM node indicates a very high likelihood of malignant involvement on ultrasound-guided FNA. The presences of high tumor grade, LVI, or triple receptor-negative status are risk factors for IM node positivity on (18)F-FDG PET/CT.

Positron emission mammography (PEM): effect of activity concentration, object size, and object contrast on phantom lesion detection.

PURPOSE: To characterize the relationship between lesion detection sensitivity and injected activity as a function of lesion size and contrast on the PEM (positron emission mammography) Flex Solo II scanner using phantom experiments. METHODS: Phantom lesions (spheres 4, 8, 12, 16, and 20 mm diameter) were randomly located in uniform background. Sphere activity concentrations were 3 to 21 times the background activity concentration (BGc). BGc was a surrogate for injected activity; BGc ranged from 0.44-4.1 kBq∕mL, corresponding to 46-400 MBq injections. Seven radiologists read 108 images containing zero, one, or two spheres. Readers used a 5-point confidence scale to score the presence of spheres. RESULTS: Sensitivity was 100% for lesions ≥12 mm under all conditions except for one 12 mm sphere with the lowest contrast and lowest BGc (60% sensitivity). Sensitivity was 100% for 8 mm spheres when either contrast or BGc was high, and 100% for 4 mm spheres only when both contrast and BGc were highest. Sphere contrast recovery coefficients (CRC) were 49%, 34%, 26%, 14%, and 2.8% for the largest to smallest spheres. Cumulative specificity was 98%. CONCLUSIONS: Phantom lesion detection sensitivity depends more on sphere size and contrast than on BGc. Detection sensitivity remained ≥90% for injected activities as low as 100 MBq, for lesions ≥8 mm. Low CRC in 4 mm objects results in moderate detection sensitivity even for 400 MBq injected activity, making it impractical to optimize injected activity for such lesions. Low CRC indicates that when lesions <8 mm are observed on PEM images they are highly tracer avid with greater potential of clinical significance. High specificity (98%) suggests that image statistical noise does not lead to false positive findings. These results apply to the 85 mm thick object used to obtain them; lesion detectability should be better (worse) for thinner (thicker) objects based on the reduced (increased) influence of photon attenuation.

Toxicogenomic analysis of chlorine vapor-induced porcine skin injury.

Chlorine is an industrial chemical that can cause cutaneous burns. Understanding the molecular mechanisms of tissue damage and wound healing is important for the selection and development of an effective post-exposure treatment. This study investigated the effect of cutaneous chlorine vapor exposure using a weanling swine burn model and microarray analysis. Ventral abdominal sites were exposed to a mean calculated chlorine vapor concentration of 2.9 g/L for 30 min. Skin samples were harvested at 1.5 h, 3 h, 6 h, and 24 h post-exposure and stored in RNAlater(®) until processing. Total RNA was isolated, processed, and hybridized to Affymetrix GeneChip(®) Porcine Genome Arrays. Differences in gene expression were observed with respect to sampling time. Ingenuity Pathways Analysis revealed seven common biological functions among the top ten functions of each time point, while canonical pathway analysis revealed 3 genes (IL-6, IL1A, and IL1B) were commonly shared among three significantly altered signaling pathways. The transcripts encoding all three genes were identified as common potential therapeutic targets for Phase II/III clinical trial, or FDA-approved drugs. The present study shows transcriptional profiling of cutaneous wounds induced by chlorine exposure identified potential targets for developing therapeutics against chlorine-induced skin injury.

Crumbling the Castle: Targeting DNABII Proteins for Collapsing Bacterial Biofilms as a Therapeutic Approach to Treat Disease and Combat Antimicrobial Resistance.

Antimicrobial resistance (AMR) is a concerning global threat that, if not addressed, could lead to increases in morbidity and mortality, coupled with societal and financial burdens. The emergence of AMR bacteria can be attributed, in part, to the decreased development of new antibiotics, increased misuse and overuse of existing antibiotics, and inadequate treatment options for biofilms formed during bacterial infections. Biofilms are complex microbiomes enshrouded in a self-produced extracellular polymeric substance (EPS) that is a primary defense mechanism of the resident microorganisms against antimicrobial agents and the host immune system. In addition to the physical protective EPS barrier, biofilm-resident bacteria exhibit tolerance mechanisms enabling persistence and the establishment of recurrent infections. As current antibiotics and therapeutics are becoming less effective in combating AMR, new innovative technologies are needed to address the growing AMR threat. This perspective article highlights such a product, CMTX-101, a humanized monoclonal antibody that targets a universal component of bacterial biofilms, leading to pathogen-agnostic rapid biofilm collapse and engaging three modes of action-the sensitization of bacteria to antibiotics, host immune enablement, and the suppression of site-specific tissue inflammation. CMTX-101 is a new tool used to enhance the effectiveness of existing, relatively inexpensive first-line antibiotics to fight infections while promoting antimicrobial stewardship.

Positron emission mammography: correlation of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 status and 18F-FDG.

OBJECTIVE: The study objective was to assess the correlation between (18)F-FDG uptake values on positron emission mammography (PEM), expressed as maximum uptake value and lesion-to-background ratio, and receptor status (i.e., estrogen receptor [ER], progesterone receptor [PR], and human epidermal growth factor receptor 2 [HER2]), tumor histology, and tumor grade. We also evaluated for the correlation between maximum uptake value on PEM and maximum uptake value on a whole-body PET/CT. MATERIALS AND METHODS: We retrospectively reviewed our database for patients with newly diagnosed breast cancer who were referred for PEM between June 2007 and September 2009. A subset of patients also underwent a whole-body PET/CT scan. The original pathology reports were reviewed to establish the histologic type, grade, and receptor status. RESULTS: The study involved 98 patients with 100 lesions. ER-negative tumors and PR-negative tumors had significantly higher mean lesion-to-background ratio than did their respective receptor-positive tumors (p = 0.02). Triple-negative tumors (i.e., ER-negative, PR-negative, and HER2-negative tumors) had statistically higher mean lesion-to-background ratio than did ER-positive PR-positive HER2-negative tumors (p = 0.04). Infiltrating ductal carcinomas had significantly higher PEM FDG uptake values than did infiltrating lobular carcinomas (p = 0.02-0.04). Breast tumors with higher histologic grade also had significantly higher PEM FDG uptake values than did those with lower grade (p = 0.03 and p < 0.001). A moderately high correlation (0.76-0.79) was seen between whole-body PET/CT and PEM uptake values. CONCLUSION: This study shows a correlation between PEM FDG uptake values and the prognostic factors that have been shown to predict breast cancer survival.

An assessment of transcriptional changes in porcine skin exposed to bromine vapor.

Bromine is an industrial chemical that can cause severe cutaneous burns. This study was a preliminary investigation into the effect of cutaneous exposure to bromine vapor using a weanling swine burn model and microarray analysis. Ventral abdominal sites were exposed to a mean calculated bromine vapor concentration of 0.69 g L(-1) for 10 or 20 min. At 48 h postexposure, total RNA from skin samples was isolated, processed, and hybridized to Affymetrix GeneChip Porcine Genome Arrays. Expression analysis revealed that bromine vapor exposure for 10 or 20 min promoted similar transcriptional changes in the number of significantly modulated probe sets. A minimum of 83% of the probe sets was similar for both exposure times. Ingenuity pathways analysis revealed eight common biological functions among the top 10 functions of each experimental group, in which 30 genes were commonly shared among 19 significantly altered signaling pathways. Transcripts encoding heme oxygenase 1, interleukin-1ß, interleukin 2 receptor gamma chain, and plasminogen activator inhibitor-1 were identified as common potential therapeutic targets for Phase II/III clinical trial or FDA-approved drugs. The present study is an initial assessment of the transcriptional responses to cutaneous bromine vapor exposure identifying molecular networks and genes that could serve as targets for developing therapeutics for bromine-induced skin injury.

Temporal effects in porcine skin following bromine vapor exposure.

Bromine is an industrial chemical that causes severe cutaneous burns. When selecting or developing effective treatments for bromine burns, it is important to understand the molecular mechanisms of tissue damage and wound healing. This study investigated the effect of cutaneous bromine vapor exposure on gene expression using a weanling swine burn model by microarray analysis. Ventral abdominal sites were exposed to a mean calculated bromine vapor concentration of 0.51 g/L for 7 or 17 min. At 6 h, 48 h, and 7 days post-exposure, total RNA from skin samples was isolated, processed, and analyzed with Affymetrix GeneChip® Porcine Genome Arrays (N = 3 per experimental group). Differences in gene expression were observed with respect to exposure duration and sampling time. Ingenuity Pathways Analysis (IPA) revealed four common biological functions (cancer, cellular movement, cell-to-cell signaling and interaction, and tissue development) among the top ten functions of each experimental group, while canonical pathway analysis revealed 9 genes (ARG2, CCR1, HMOX1, ATF2, IL-8, TIMP1, ESR1, HSPAIL, and SELE) that were commonly shared among four significantly altered signaling pathways. Among these, the transcripts encoding HMOX1 and ESR1 were identified using IPA as common potential therapeutic targets for Phase II/III clinical trial or FDA-approved drugs. The present study describes the transcriptional responses to cutaneous bromine vapor exposure identifying molecular networks and genes that could serve as targets for developing therapeutics for bromine-induced skin injury.

Environmental persistence of a highly pathogenic avian influenza (H5N1) virus.

Human cases of disease caused by highly pathogenic avian influenza (HPAI) viruses of the H5N1 subtype are rare, yet characterized with a mortality rate of approximately 60%. Tests were conducted to determine the environmental persistence of an HPAI (H5N1) virus on four materials (glass, wood, galvanized metal, and topsoil) that could act as fomites or harbor the virus. Test coupons were inoculated with the virus and exposed to one of five environmental conditions that included changes in temperature, relative humidity, and simulated sunlight. At time periods up to 13 days, the virus was extracted from each coupon, and quantified via cytopathic effects on Madin-Darby canine kidney cells. The virus was most persistent under the low temperature condition, with less than 1 log reduction on glass and steel after 13 days at low relative humidity. Thus, at these conditions, the virus would be expected to persist appreciably beyond 13 days.

A review of transcriptomics in cutaneous chemical exposure.

Monitoring gene expression profiles in the skin using microarrays has become a useful approach to enhance the understanding of dermal function, toxicologic mechanisms, and risk assessment. With respect to cutaneous chemical exposure, there are few transcriptomic studies in the published literature, and these often differ in experimental design and availability of raw data. An assessment of multiple microarray data sets could be advantageous for identifying potential redundant biological mechanisms or genes associated with dermal responses to chemical exposure. As in vivo cutaneous chemical exposure models can vary, extrapolations from analyzing multiple cross-species microarray data sets could aid in identifying a general set of pathways or genes that could guide future study direction and evaluation of dermal toxicologic assessments and potential therapeutic intervention. This review provides a summary of studies in the open literature that utilize transcriptomics in assessing the molecular responses in chemical-exposed skin with an intent of determining whether biomarkers could be identified and the potential for future meta-analyses.

Transcriptional changes in porcine skin at 7 days following sulfur mustard and thermal burn injury.

Severe cutaneous injuries continue to result from exposure to sulfur mustard [bis(2-chloroethyl)sulfide; HD] and thermal burns. Microarray analysis was utilized in this study to evaluate transcriptional changes in porcine skin assessing the underlying repair mechanisms of HD and thermal injury involved in wound healing. Four ventral abdominal sites on each of 4 weanling swine were exposed to 400 microL undiluted HD or a heated brass rod (70 degrees C) for 8 minutes and 45-60 seconds, respectively. At 7 days postexposure, skin samples were excised and total RNA was isolated, labeled, and hybridized to Affymetrix GeneChip (Santa Clara, CA, USA) Porcine Genome Arrays (containing 20,201 genes). Based on the gene expression patterns in HD- and thermal-exposed skin at 7 days, the transcriptional profiles do not differ greatly. HD and thermal exposures promoted similar changes in transcription, where 270 and 283 transcripts were increased with HD and thermal exposures, respectively. Both exposures promoted decreases in 317 and 414 transcripts, respectively. Of the significantly increased transcripts, at least 77% were commonly expressed in both HD- and thermal-exposed skin, whereas at least 67% of decreased transcripts were common between both exposure types. Six of the top 10 biological functions were common to HD and thermal injury in which 9 canonical pathways were shared. The present study illustrates the similarities found between HD and thermal injury with respect to transcriptional response and wound healing and identifies specific genes (CXCL2, CXCR4, FGFR2, HMOX1, IGF1, PF4, PLAU, PLAUR, S100A8, SPP1, and TNC) that may be useful as potential therapeutic targets to promote improved wound healing.

Gene expression analysis of bromine-induced burns in porcine skin.

Bromine is an industrial chemical that is irritating to the skin and causes cutaneous burns. An important factor in selecting or developing an effective treatment is to understand the underlying molecular mechanisms of tissue damage and wound healing. This study used a weanling swine burn model and microarray analysis to evaluate the effect of exposure length and sampling times on the transcriptional changes in response to cutaneous bromine injury. Ventral abdominal sites (N=4/treatment group) were exposed to 600microL undiluted bromine for 45 s or 8 min. At 24 h and 7d post-exposure, total RNA from skin samples was isolated, processed, and hybridized to Affymetrix GeneChip Porcine Genome Arrays. Expression analysis revealed that bromine exposure duration appeared to have less effect on the transcript changes than the sampling time. The percent transcripts changed at 24h were similar (30%) whether having a 45 s or 8 min bromine exposure; percent transcripts changed at 7d were also similar (62%) regardless of exposure length. However, only 13-14% of the transcripts were similar when comparing samples analyzed at 24h and 7d. Ingenuity Pathways Analysis (IPA) revealed six common biological functions among the top 10 functions of each experimental group, while canonical pathway analysis revealed 11 genes that were commonly shared among 24 significantly altered signaling pathways. Additionally, there were 11 signaling pathways in which there were no commonly shared transcripts. The present study is an initial assessment of the transcriptional responses to cutaneous bromine exposure identifying molecular networks and genes that could serve as targets for developing therapeutics for bromine-induced skin injury.

Transcriptional responses associated with sulfur mustard and thermal burns in porcine skin.

In military and civilian environments, serious cutaneous damage can result from thermal burns or exposure to the blistering agent sulfur mustard [bis (2-chloroethyl) sulfide; HD]. Similar therapies have historically been used to treat cutaneous thermal and HD injuries; however, the underlying molecular mechanisms of tissue damage and wound healing may differ between the types of burns. Using microarray analysis, this study assessed the transcriptional responses to cutaneous HD and thermal injury at 48 hours post-exposure to identify molecular networks and genes associated with each type of skin injury. Ventral abdominal sites on each of 4 weanling swine were exposed to 400 mul of undiluted HD or a heated brass rod (70 degrees C) for 8 minutes and 45-60 seconds, respectively. At 48 hours post-exposure, total RNA was isolated from excised skin samples and hybridized to Affymetrix GeneChip Porcine Genome Arrays (containing 20,201 genes). Both HD and thermal exposure promoted significant transcriptional changes where 290 and 267 transcripts were increased and 197 and 707 transcripts were decreased with HD and thermal exposure, respectively. HD- and thermal-injured skin expressed 149 increased and 148 decreased common transcripts. Comparison of the 10 most significantly changed biological functions for HD and thermal exposures identified 7 overlapping functional groups. Canonical pathways analysis revealed 15 separate signaling pathways containing transcripts associated with both HD and thermal exposure. Within these pathways, 5 transcripts (CXCR4, FGFR2, HMOX1, IL1R1, and TLR4) were identified as known targets for existing phase II/III clinical trial or Food and Drug Administration (FDA)-approved drugs. This study is the first to directly assess transcriptional changes in porcine skin subjected to HD or thermal injury over the same time period.

Rabbitpox in New Zealand White Rabbits: A Therapeutic Model for Evaluation of Poxvirus Medical Countermeasures Under the FDA Animal Rule.

The elimination of smallpox as an endemic disease and the obvious ethical problems with clinical challenge requires the efficacy evaluation of medical countermeasures against smallpox using the FDA Animal Rule. This approach requires the evaluation of antiviral efficacy in an animal model whose infection recapitulates the human disease sufficiently well enough to provide predictive value of countermeasure effectiveness. The narrow host range of variola virus meant that no other animal species was sufficiently susceptible to variola to manifest a disease with predictive value. To address this dilemma, the FDA, after a public forum with virologists in December 2011, suggested the development of two animal models infected with the cognate orthopoxvirus, intradermal infection of rabbits and intranasal infection of mice, to supplement the non-human primate models in use. In this manuscript, we describe the development of an intradermal challenge model of New Zealand White rabbits with rabbitpox virus (RPXV) for poxvirus countermeasure evaluation. Lethality of RPXV was demonstrated in both 9 and 16-weeks old rabbits with an LD50 < 10 PFU. The natural history of RPXV infection was documented in both ages of rabbits by monitoring the time to onset of abnormal values in clinical data at a lethal challenge of 300 PFU. All infected animals became viremic, developed a fever, exhibited weight loss, developed secondary lesions, and were euthanized after 7 or 8 days. The 16-weeks RPXV-infected animals exhibiting similar clinical signs with euthanasia applied about a day later than for 9-weeks old rabbits. For all animals, the first two unambiguous indicators of infection were detection of viral copies by quantitative polymerase chain reaction and fever at 2 and 3 days following challenge, respectively. These biomarkers provide clinically-relevant trigger(s) for initiating therapy. The major advantage for using 16-weeks NZW rabbits is that older rabbits were more robust and less subject to stress-induced death allowing more reproducible studies.

Influence of environmental conditions on the attenuation of ricin toxin on surfaces.

Ricin is a highly-toxic compound derived from castor plant beans. Several incidents involving contamination of residences and buildings due to ricin production or dissemination have occurred in recent years. The goal of this study was to determine whether ricin bioactivity could be attenuated in reasonable time via simple modifications of the indoor environment. Attenuation was assessed on six different materials as a function of temperature, relative humidity (RH), and contact time, using both a pure and crude preparation of the toxin. Ricin bioactivity was quantified via a cytotoxicity assay, and attenuation determined as the difference in ricin recovered from test and positive controls. The results showed that pure ricin could be attenuated successfully, while the crude ricin was generally more persistent and results more variable. We found no significant attenuation in crude ricin after two weeks at typical indoor environmental conditions, except on steel. Attenuation mostly improved with increasing temperature, but the effect of RH varied. For pure ricin, heat treatments at 40°C for 5 days or 50°C for 2-3 days achieved greater than 96% attenuation on steel. In contrast, appreciable recovery of the crude ricin preparation still occurred at 40°C after two weeks.

Ectromelia Virus Disease Characterization in the BALB/c Mouse: A Surrogate Model for Assessment of Smallpox Medical Countermeasures.

In 2007, the United States- Food and Drug Administration (FDA) issued guidance concerning animal models for testing the efficacy of medical countermeasures against variola virus (VARV), the etiologic agent for smallpox. Ectromelia virus (ECTV) is naturally-occurring and responsible for severe mortality and morbidity as a result of mousepox disease in the murine model, displaying similarities to variola infection in humans. Due to the increased need of acceptable surrogate animal models for poxvirus disease, we have characterized ECTV infection in the BALB/c mouse. Mice were inoculated intranasally with a high lethal dose (125 PFU) of ECTV, resulting in complete mortality 10 days after infection. Decreases in weight and temperature from baseline were observed eight to nine days following infection. Viral titers via quantitative polymerase chain reaction (qPCR) and plaque assay were first observed in the blood at 4.5 days post-infection and in tissue (spleen and liver) at 3.5 days post-infection. Adverse clinical signs of disease were first observed four and five days post-infection, with severe signs occurring on day 7. Pathological changes consistent with ECTV infection were first observed five days after infection. Examination of data obtained from these parameters suggests the ECTV BALB/c model is suitable for potential use in medical countermeasures (MCMs) development and efficacy testing.

Positron Emission Mammography Image Interpretation for Reduced Image Count Levels.

UNLABELLED: We studied the effects of reduced (18)F-FDG injection activity on interpretation of positron emission mammography (PEM) images and compared image interpretation between 2 postinjection imaging times. METHODS: We performed a receiver-operating-characteristic (ROC) study using PEM images reconstructed with different count levels expected from injected activities between 23 and 185 MBq. Thirty patients received 2 PEM scans at postinjection times of 60 and 120 min. Half of the patients were scanned with a standard protocol; the others received one-half of the standard activity. Images were reconstructed using 100%, 50%, and 25% of the total counts acquired. Eight radiologists used a 5-point confidence scale to score 232 PEM images for the presence of up to 3 malignant lesions. Paired images were analyzed with conditional logistic regression and ROC analysis to investigate changes in interpretation. RESULTS: There was a trend for increasing lesion detection sensitivity with increased image counts: odds ratios were 2.2 (P = 0.01) and 1.9 (P = 0.04) per doubling of image counts for 60- and 120-min uptake images, respectively, without significant difference between time points (P = 0.7). The area under the ROC curve (AUC) was highest for the 100%-count, 60-min images (0.83 vs. 0.75 for 50%-counts, P = 0.02). The 120-min images had a similar trend but did not reach statistical significance (AUC = 0.79 vs. 0.73, P = 0.1). Our data did not yield significant trends between specificity and image counts. Lesion-to-background ratios increased between 60- and 120-min scans (P < 0.001). CONCLUSION: Reducing the image counts relative to the standard protocol decreased diagnostic accuracy. The increase in lesion-to-background ratio between 60- and 120-min uptake times was not enough to improve detection sensitivity in this study, perhaps in part due to fewer counts in the later scan.

Environmental Persistence of Bacillus anthracis and Bacillus subtilis Spores.

There is a lack of data for how the viability of biological agents may degrade over time in different environments. In this study, experiments were conducted to determine the persistence of Bacillus anthracis and Bacillus subtilis spores on outdoor materials with and without exposure to simulated sunlight, using ultraviolet (UV)-A/B radiation. Spores were inoculated onto glass, wood, concrete, and topsoil and recovered after periods of 2, 14, 28, and 56 days. Recovery and inactivation kinetics for the two species were assessed for each surface material and UV exposure condition. Results suggest that with exposure to UV, decay of spore viability for both Bacillus species occurs in two phases, with an initial rapid decay, followed by a slower inactivation period. The exception was with topsoil, in which there was minimal loss of spore viability in soil over 56 days, with or without UV exposure. The greatest loss in viable spore recovery occurred on glass with UV exposure, with nearly a four log10 reduction after just two days. In most cases, B. subtilis had a slower rate of decay than B. anthracis, although less B. subtilis was recovered initially.

The cytotoxicity of volatile JP-8 jet fuel components in keratinocytes.

In vitro models are being used to evaluate the toxic and irritating effects of JP-8, a kerosene-based jet fuel. JP-8 components are volatile, which makes in vitro studies difficult to evaluate dose-response relationships due to changes in chemical dosimetry caused by evaporation from the exposure medium. An in vitro approach testing volatile chemical toxicity that we have recently developed was used to evaluate the toxicity of the JP-8 components m-xylene, 1-methylnaphthalene (1-MN), and n-nonane in keratinocytes. Partition coefficients were measured and used to estimate the chemical concentration in the keratinocytes. The EC50 for m-xylene and 1-MN decreased significantly (P < or = 0.05) at 1, 2, and 4h. For n-nonane, no significant decreases in the EC50 values were observed over time; marginal cytotoxicity of n-nonane in keratinocytes was observed at 1h. Within 4h, about 75-90% of each volatile chemical was observed to be lost from the exposure medium when tissues were exposed in unsealed 24-well plates. This decrease resulted in significantly higher medium chemical concentrations needed to obtain EC50 values when compared to tissues exposed in sealed vials. This study demonstrates that chemical evaporation during in vitro exposures can significantly affect toxicological endpoint measurements. Ultimately, relating target cell chemical concentration to cellular responses in vitro could be used in determining an equivalent external dose using a biologically-based mathematical model.