Antimicrobial use and antimicrobial resistance monitoring in pig production in the United States of America

Monitoring antimicrobial use (AMU) and antimicrobial resistance (AMR) on farms is recognised as an important component of antimicrobial stewardship, yet the process can be resource intensive. This paper describes a subset of findings from the first year of a collaboration across government, academia and a private sector veterinary practice focused on swine production in the Midwestern United States. The work is supported by participating farmers and the greater swine industry. Twice-annual collection of samples from pigs along with AMU monitoring occurred on 138 swine farms. Detection and resistance of Escherichia coli from pig tissues was assessed, and associations between AMU and AMR were evaluated. This paper describes the methods utilised and the first-year E. coli-related results from this project. Higher minimum inhibitory concentrations (MIC) for enrofloxacin and danofloxacin in E. coli from swine tissues were associated with the purchase of fluoroquinolones. There were no other significant associations between MIC and AMU combinations in E. coli isolated from pig tissues. This project represents one of the first attempts to monitor AMU as well as AMR in E. coli in a large-scale commercial swine system in the United States of America.

Exploring innovative radiation shielding approaches in space: A material and design study for a wearable radiation protection spacesuit

We present a design study for a wearable radiation-shielding spacesuit, designed to protect astronauts' most radiosensitive organs. The suit could be used in an emergency, to perform necessary interventions outside a radiation shelter in the space habitat in case of a Solar Proton Event (SPE). A wearable shielding system of the kind we propose has the potential to prevent the onset of acute radiation effects in this scenario. In this work, selection of materials for the spacesuit elements is performed based on the results of dedicated GRAS/Geant4 1-dimensional Monte Carlo simulations, and after a trade-off analysis between shielding performance and availability of resources in the space habitat. Water is the first choice material, but also organic compounds compatible with a human space habitat are considered (such as fatty acids, gels and liquid organic wastes). Different designs and material combinations are proposed for the spacesuits. To quantify shielding performance we use GRAS/Geant4 simulations of an anthropomorphic phantom in an average SPE environment, with and without the spacesuit, and we compare results for the dose to Blood Forming Organs (BFO) in Gy-Eq, i.e. physical absorbed dose multiplied by the proton Relative Biological Effectiveness (RBE) for non-cancer effects. In case of SPE occurrence for Intra-Vehicular Activities (IVA) outside a radiation shelter, dose reductions to BFO in the range of 44-57% are demonstrated to be achievable with the spacesuit designs made only of water elements, or of multi-layer protection elements (with a thin layer of a high density material covering the water filled volume). Suit elements have a thickness in the range 2-6 cm and the total mass for the garment sums up to 35-43 kg depending on model and material combination. Dose reduction is converted into time gain, i.e. the increase of time interval between the occurrence of a SPE and the moment the dose limit to the BFO for acute effects is reached. Wearing a radiation shielding spacesuit of the kind we propose, the astronaut could have up to more than the double the time (e.g. almost 6 instead of 2.5 h) to perform necessary interventions outside a radiation shelter during a SPE, his/her exposure remaining within dose limits. An indicative mass saving thanks to the shielding provided by the suits is also derived, calculating the amount of mass needed in addition to the 1.5 cm thick Al module considered for the IVA scenario to provide the same additional shielding given by the spacesuit. For an average 50% dose reduction to BFO this is equal to about 2.5 tons of Al. Overall, our results offer a proof-of-principle validation of a complementary personal shielding strategy in emergency situations in case of a SPE event. Such results pave the way for the design and realization of a prototype of a water-filled garment to be tested on board the International Space Station for wearability. A successful outcome will possibly lead to the further refining of the design of radiation protection spacesuits and their possible adoption in future long-duration manned missions in deep space.

Monte Carlo simulations for the space radiation superconducting shield project (SR2S)

Astronauts on deep-space long-duration missions will be exposed for long time to galactic cosmic rays (GCR) and Solar Particle Events (SPE). The exposure to space radiation could lead to both acute and late effects in the crew members and well defined countermeasures do not exist nowadays. The simplest solution given by optimized passive shielding is not able to reduce the dose deposited by GCRs below the actual dose limits, therefore other solutions, such as active shielding employing superconducting magnetic fields, are under study. In the framework of the EU FP7 SR2S Project - Space Radiation Superconducting Shield--a toroidal magnetic system based on MgB2 superconductors has been analyzed through detailed Monte Carlo simulations using Geant4 interface GRAS. Spacecraft and magnets were modeled together with a simplified mechanical structure supporting the coils. Radiation transport through magnetic fields and materials was simulated for a deep-space mission scenario, considering for the first time the effect of secondary particles produced in the passage of space radiation through the active shielding and spacecraft structures. When modeling the structures supporting the active shielding systems and the habitat, the radiation protection efficiency of the magnetic field is severely decreasing compared to the one reported in previous studies, when only the magnetic field was modeled around the crew. This is due to the large production of secondary radiation taking place in the material surrounding the habitat.

Epithelial displacement after stereotactic 11-gauge directional vacuum-assisted breast biopsy

OBJECTIVE

Displaced epithelial fragments at percutaneous biopsy of ductal carcinoma in situ (DCIS) may mimic stromal invasion. This study was undertaken to determine the frequency of epithelial displacement in DCIS lesions of patients who underwent stereotactic 11-gauge directional vacuum-assisted breast biopsy.

MATERIALS AND METHODS

We retrospectively reviewed 28 consecutive DCIS lesions in patients who underwent stereotactic 11-gauge directional vacuum-assisted breast biopsy followed by surgery. Surgical specimens were examined for histologic evidence of epithelial displacement, consisting of fragments of epithelium in artifactual spaces in breast parenchyma or in lymphovascular channels, accompanied by hemorrhage, fat necrosis, inflammation, hemosiderin-laden macrophages, or granulation tissue.

RESULTS

The median number of specimens obtained per lesion was 14 (range, seven to 45). The median interval from stereotactic biopsy to surgery was 27 days (range, 10-59 days). Surgery revealed DCIS in 19 (68%) of 28 lesions, DCIS and infiltrating carcinoma in four lesions (14%), and no residual carcinoma in five lesions (18%). Reactive changes at the biopsy site were identified in all cases. Displacement of benign epithelium into granulation tissue at the stereotactic biopsy site was identified in two cases (7%). We found no evidence of displacement of malignant epithelium.

CONCLUSION

Epithelial displacement is uncommon after stereotactic 11-gauge directional vacuum-assisted biopsy of the breast. We observed displacement of benign epithelium in two (7%) of 28 DCIS lesions and no displacement of malignant epithelium.