Dust Under the Radar: Rethinking How to Evaluate the Impacts of Dust Events on Air Quality in the United States.

Dust is an important and complex constituent of the atmospheric system, having significant impacts on the environment, climate, air quality, and human health. Although dust events are common across many regions of the United States, their impacts are not often prioritized in air quality mitigation strategies. We argue that there are at least three factors that result in underestimation of the social and environmental impact of dust events, making them receive less attention. These include (a) sparse monitoring stations with irregular spatial distribution in dust-influenced regions, (b) inconsistency with dust sampling methods, and (c) sampling frequency and schedules, which can lead to missed dust events or underestimation of dust particle concentrations. Without addressing these three factors, it is challenging to characterize and understand the full air quality impacts of dust events in the United States. This paper highlights the need for additional monitoring to measure these events so that we can more fully evaluate and understand their impacts, as they are predicted to increase with climate change.

Visibility impacts at Class I areas near the Bakken oil and gas development.

Oil and gas activities have occurred in the Bakken region of North Dakota and nearby states and provinces since the 1950s but began increasing rapidly around 2008 due to new extraction methods. Three receptor-based techniques were used to examine the potential impacts of oil and gas extraction activities on airborne particulate concentrations in Class I areas in and around the Bakken. This work was based on long-term measurements from the Interagency Monitoring of Protected Visual Environments (IMPROVE) monitoring network. Spatial and temporal patterns in measured concentrations were examined before and after 2008 to better characterize the influence of these activities. A multisite back-trajectory analysis and a receptor-based source apportionment model were used to estimate impacts. Findings suggest that recent Bakken oil and gas activities have led to an increase in regional fine (PM2.5-particles with aerodynamic diameters <2.5 µm) soil and elemental carbon (EC) concentrations, as well as coarse mass (CM = PM10-PM2.5). Influences on sulfate and nitrate concentrations were harder to discern due to the concurrent decline in regional emissions of precursors to these species from coal-fired electric generating stations. Impacts were largest at sites in North Dakota and Montana that are closest to the most recent drilling activity. IMPLICATIONS: The increase in oil and gas activities in the Bakken region of North Dakota and surrounding areas has had a discernible impact on airborne particulate concentrations that impact visibility at protected sites in the region. However, the impact has been at least partially offset by a concurrent reduction in emissions from coal-fired electric generating stations. Continuing the recent reductions in flaring would likely be beneficial for the regional visual air quality.

Leukocytoclastic vasculitis in children: clinical characteristics, subtypes, causes and direct immunofluorescence findings of 56 biopsy-confirmed cases.

BACKGROUND: Leukocytoclastic vasculitis (LCV) in children is a complex group of conditions. OBJECTIVES: This study presents the demographics, clinical features, direct immunofluorescence (DIF) results and suspected aetiologies of 56 biopsy-confirmed cases of leukocytoclastic vasculitis in children. METHODS: Retrospective review of 56 children seen at Mayo Clinic in Rochester, Minnesota, from 1993 to 2013 with clinical features and cutaneous biopsy consistent with LCV. RESULTS: Twenty-seven (48%) cases were found to be due to IgA vasculitis (Henoch-Schonlein purpura). The remaining cases were found to be due to cutaneous small-vessel vasculitis (n = 19, 34%), urticarial vasculitis (n = 5, 9%), ANCA-associated vasculitis (n = 4, 7%) and acute haemorrhagic oedema of infancy (n = 1, 2%). IgA vasculitis was found to be associated with abdominal pain (P = 0.008), whereas the non-IgA vasculitis group was associated with headache (P = 0.052). Children with IgA vasculitis had palpable purpura (P = <0.001), petechia (P = 0.057), vesicles (P = 0.009) and involvement of the buttock (P = 0.004) more frequently than the non-IgA vasculitis group. On DIF, perivascular IgA was positive in IgA vasculitis compared to non-IgA vasculitis cases (P = <0.001), the other conjugates were similar between the two groups. CONCLUSION: The most common subtype of biopsy-confirmed LCV in children is IgA vasculitis. Clinical features, exam characteristics and DIF results can be helpful in determining the subtype of cutaneous vasculitis in children.

Assessment of computational tools for MRI RF dosimetry by comparison with measurements on a laboratory phantom.

This paper presents an extended comparison between numerical simulations using the different computational tools employed nowadays in electromagnetic dosimetry and measurements of radiofrequency (RF) electromagnetic field distributions in phantoms with tissue-simulating liquids at 64 MHz, 128 MHz and 300 MHz, adopting a customized experimental setup. The aim is to quantify the overall reliability and accuracy of RF dosimetry approaches at frequencies in use in magnetic resonance imaging transmit coils. Measurements are compared against four common techniques used for electromagnetic simulations, i.e. the finite difference time domain (FDTD), the finite integration technique (FIT), the boundary element method (BEM) and the hybrid finite element method-boundary element method (FEM-BEM) approaches. It is shown that FDTD and FIT produce similar results, which generally are also in good agreement with those of FEM-BEM. On the contrary, BEM seems to perform less well than the other methods and shows numerical convergence problems in presence of metallic objects. Maximum uncertainties of about 30% (coverage factor k = 2) can be attributed to measurements regarding electric and magnetic field amplitudes. Discrepancies between simulations and experiments are found to be in the range from 10% to 30%. These values confirm other previously published results of experimental validations performed on a limited set of data and define the accuracy of our measurement setup.

Transmission of methicillin-resistant Staphylococcus aureus via deceased donor liver transplantation confirmed by whole genome sequencing.

Donor-derived bacterial infection is a recognized complication of solid organ transplantation (SOT). The present report describes the clinical details and successful outcome in a liver transplant recipient despite transmission of methicillin-resistant Staphylococcus aureus (MRSA) from a deceased donor with MRSA endocarditis and bacteremia. We further describe whole genome sequencing (WGS) and complete de novo assembly of the donor and recipient MRSA isolate genomes, which confirms that both isolates are genetically 100% identical. We propose that similar application of WGS techniques to future investigations of donor bacterial transmission would strengthen the definition of proven bacterial transmission in SOT, particularly in the presence of highly clonal bacteria such as MRSA. WGS will further improve our understanding of the epidemiology of bacterial transmission in SOT and the risk of adverse patient outcomes when it occurs.

High-intensity focused ultrasound: advances in technology and experimental trials support enhanced utility of focused ultrasound surgery in oncology.

High-intensity focused ultrasound (HIFU) is a rapidly maturing technology with diverse clinical applications. In the field of oncology, the use of HIFU to non-invasively cause tissue necrosis in a defined target, a technique known as focused ultrasound surgery (FUS), has considerable potential for tumour ablation. In this article, we outline the development and underlying principles of HIFU, overview the limitations and commercially available equipment for FUS, then summarise some of the recent technological advances and experimental clinical trials that we predict will have a positive impact on extending the role of FUS in cancer therapy.

The European Federation of Organisations for Medical Physics Policy Statement No 14: the role of the Medical Physicist in the management of safety within the magnetic resonance imaging environment: EFOMP recommendations.

This European Federation of Organisations for Medical Physics (EFOMP) Policy Statement outlines the way in which a Safety Management System can be developed for MRI units. The Policy Statement can help eliminate or at least minimize accidents or incidents in the magnetic resonance environment and is recommended as a step towards harmonisation of safety of workers, patients, and the general public regarding the use of magnetic resonance imaging systems in diagnostic and interventional procedures.

Transrectal high-intensity focused ultrasonography is feasible as a new therapeutic option for advanced recurrent rectal cancer: report on the first case worldwide.

High-intensity focused ultrasonography is the only completely non-invasive thermal therapy. To date its applications have been limited but clinical indications are expanding with enhanced technological advances that have increased the accuracy of targeting and decreased the duration of treatment times. We report its first use for rectal cancer.

Genetic analysis of inherited bone marrow failure syndromes from one prospective, comprehensive and population-based cohort and identification of novel mutations.

INTRODUCTION: Inherited bone marrow failure syndromes (IBMFSs) often have substantial phenotypic overlap, thus genotyping is often critical for establishing a diagnosis. OBJECTIVES AND METHODS: To determine the genetic characteristics and mutation profiles of IBMFSs, a comprehensive population-based study that prospectively enrols all typical and atypical cases without bias is required. The Canadian Inherited Marrow Failure Study is such a study, and was used to extract clinical and genetic information for patients enrolled up to May 2010. RESULTS: Among the 259 primary patients with IBMFS enrolled in the study, the most prevalent categories were Diamond-Blackfan anaemia (44 patients), Fanconi anaemia (39) and Shwachman-Diamond syndrome (35). The estimated incidence of the primary IBMFSs was 64.5 per 10(6) births, with Fanconi anaemia having the highest incidence (11.4 cases per 10(6) births). A large number of patients (70) had haematological and non-haematological features that did not fulfil the diagnostic criteria of any specific IBMFS category. Disease-causing mutations were identified in 53.5% of the 142 patients tested, and in 16 different genes. Ten novel mutations in SBDS, RPL5, FANCA, FANCG, MPL and G6PT were identified. The most common mutations were nonsense (31 alleles) and splice site (28). Genetic heterogeneity of most IBMFSs was evident; however, the most commonly mutated gene was SBDS, followed by FANCA and RPS19. CONCLUSION: From this the largest published comprehensive cohort of IBMFSs, it can be concluded that recent advances have led to successful genotyping of about half of the patients. Establishing a genetic diagnosis is still challenging and there is a critical need to develop novel diagnostic tools.

Comparative analysis of Shwachman-Diamond syndrome to other inherited bone marrow failure syndromes and genotype-phenotype correlation.

Our knowledge of the phenotypes of inherited bone marrow failure syndromes (IBMFSs) derives from case reports or case series in which only one IBMFS was studied. However, the substantial phenotypic overlap necessitates comparative analysis between the IBMFSs. Shwachman-Diamond syndrome (SDS) is an IBMFS that the appreciation of what comprises its clinical phenotype is still evolving. In this analysis we used data on 125 patients from the Canadian Inherited Marrow Failure Study (CIMFS), which is a prospective multicenter population-based study. Thirty-four cases of SDS patients were analyzed and compared to other patients with the four most common IBMFSs on the CIMFS: Diamond Blackfan anemia, Fanconi anemia (FA), Kostmann/severe congenital neutropenia and dyskeratosis congenita (DC). The diagnosis of SDS, FA and DC was often delayed relative to symptoms onset; indicating a major need for improving tools to establish a rapid diagnosis. We identified multiple phenotypic differences between SDS and other IBMFSs, including several novel differences. SBDS biallelic mutations were less frequent than in previous reports (81%). Importantly, compared to patients with biallelic mutations, patients with wild type SBDS had more severe hematological disease but milder pancreatic disease. In conclusion, comprehensive study of the IBMFSs can provide useful comparative data between the disorders. SBDS-negative SDS patients may have more severe hematological failure and milder pancreatic disease.

Numerical study of RF exposure and the resulting temperature rise in the foetus during a magnetic resonance procedure.

Numerical simulations of specific absorption rate (SAR) and temperature changes in a 26-week pregnant woman model within typical birdcage body coils as used in 1.5 T and 3 T MRI scanners are described. Spatial distributions of SAR and the resulting spatial and temporal changes in temperature are determined using a finite difference time domain method and a finite difference bio-heat transfer solver that accounts for discrete vessels. Heat transfer from foetus to placenta via the umbilical vein and arteries as well as that across the foetal skin/amniotic fluid/uterine wall boundaries is modelled. Results suggest that for procedures compliant with IEC normal mode conditions (maternal whole-body averaged SAR(MWB) < or = 2 W kg(-1) (continuous or time-averaged over 6 min)), whole foetal SAR, local foetal SAR(10 g) and average foetal temperature are within international safety limits. For continuous RF exposure at SAR(MWB) = 2 W kg(-1) over periods of 7.5 min or longer, a maximum local foetal temperature >38 degrees C may occur. However, assessment of the risk posed by such maximum temperatures predicted in a static model is difficult because of frequent foetal movement. Results also confirm that when SAR(MWB) = 2 W kg(-1), some local SAR(10g) values in the mother's trunk and extremities exceed recommended limits.

A random phased array device for delivery of high intensity focused ultrasound.

Randomized phased arrays can offer electronic steering of a single focus and simultaneous multiple foci concomitant with low levels of secondary maxima and are potentially useful as sources of high intensity focused ultrasound (HIFU). This work describes laboratory testing of a 1 MHz random phased array consisting of 254 elements on a spherical shell of radius of curvature 130 mm and diameter 170 mm. Acoustic output power and efficiency are measured for a range of input electrical powers, and field distributions for various single- and multiple-focus conditions are evaluated by a novel technique using an infrared camera to provide rapid imaging of temperature changes on the surface of an absorbing target. Experimental results show that the array can steer a single focus laterally to at least +/-15 mm off axis and axially to more than +/-15 mm from the centre of curvature of the array and patterns of four and five simultaneous foci +/-10 mm laterally and axially whilst maintaining low intensity levels in secondary maxima away from the targeted area in good agreement with linear theoretical predictions. Experiments in which pork meat was thermally ablated indicate that contiguous lesions several cm(3) in volume can be produced using the patterns of multiple foci.

The first case of Lassa fever imported from Mali to the United Kingdom, February 2009.

This is the first case of Lassa fever to be imported from Mali to the United Kingdom. This paper discusses the investigations, the virological analysis, the surveillance and management of contacts undertaken following a case of Lassa fever.

Modelling the interaction of electromagnetic fields (10 MHz-10 GHz) with the human body: methods and applications.

Numerical modelling of the interaction between electromagnetic fields (EMFs) and the dielectrically inhomogeneous human body provides a unique way of assessing the resulting spatial distributions of internal electric fields, currents and rate of energy deposition. Knowledge of these parameters is of importance in understanding such interactions and is a prerequisite when assessing EMF exposure or when assessing or optimizing therapeutic or diagnostic medical applications that employ EMFs. In this review, computational methods that provide this information through full time-dependent solutions of Maxwell's equations are summarized briefly. This is followed by an overview of safety- and medical-related applications where modelling has contributed significantly to development and understanding of the techniques involved. In particular, applications in the areas of mobile communications, magnetic resonance imaging, hyperthermal therapy and microwave radiometry are highlighted. Finally, examples of modelling the potentially new medical applications of recent technologies such as ultra-wideband microwaves are discussed.

Comparison of simulated and experimental results from helical antennas within a muscle-equivalent phantom.

Miniature microwave helical antennas for use in thermal therapy applications are usually investigated using muscle-equivalent phantoms. In this paper, an alternative method using an electromagnetic solver based on the finite integration technique is used to simulate a range of 915 MHz helical antennas within a medium with the dielectric properties of muscle. By avoiding the stair-casing effect associated with many solvers, this method enables accurate simulations of non-orthogonal geometric objects such as helical antennas to be achieved. The effects of coil-spacing and insertion depth on the SAR distribution produced by the antennas were characterized and showed good agreement with previously published results obtained using a muscle phantom and a thermographic camera. The simulations confirm that the performance of helical antennas depends on insertion depth. Modification of the coil density demonstrated improvement of the return loss characteristics and changes to the resulting SAR profile.

Epidemiological survey of central nervous system germ cell tumors in Canadian children.

OBJECTIVES: To determine the incidence and characteristics of pediatric patients with central nervous system (CNS) germ cell tumors (GCT) in Canada. METHOD: A national retrospective review of hospital charts was done on all patients with CNS GCT diagnosed between 1990 and 2004. Patients had to be under age 18 years at the time of diagnosis of a CNS germ cell tumor and be a resident of Canada. Information extracted included age and year of diagnosis, pathological diagnosis, location of tumor, evidence of disseminated disease at time of diagnosis and biological markers. RESULTS: One hundred and twenty-one cases were identified (83 germinoma; 38 non-germinoma germ cell tumor). The mean annual incidence of CNS GCT was 1.06 per million children (0.7 per million for germinoma; 0.3 per million for NGGCT). Though yearly incidences varied, there was no clear trend to increased incidence. Male predominance was noted (2.4:1 for germinoma; 11:1 for NGGCT). The primary locations were the pineal and suprasellar regions. At the time of diagnosis, disseminated disease was not uncommon (22% germinoma; 32% NGGCT). Beta human gonadotrophin was elevated in the serum, cerebrospinal fluid (CSF) or both in 7% of patients with germinoma and 36% of patients with NGGCT. Elevation of alpha-fetoprotein in serum, CSF or both was seen in 34% of patients with NGGCT. CONCLUSION: The incidence of CNS germ cell tumors in Canadian children is similar to that observed in other Western countries.

Disease progression in recently diagnosed patients with inherited marrow failure syndromes: a Canadian Inherited Marrow Failure Registry (CIMFR) report.

BACKGROUND: Inherited bone marrow failure syndromes (IMFSs) are genetic disorders characterized by defective single-lineage or multi-lineage hematopoiesis. IMFS patients are at risk for severe cytopenias, development of marrow cytogenetic abnormalities (MCA), myelodysplasia (MDS), and malignancy. The rate of disease progression and proportion of patients at risk for these complications is currently unclear. We examined recently diagnosed IMFS patients to determine distribution of diagnoses, disease progression and development of significant outcomes. METHODS: The CIMFR is a prospective multi-center study established in 2001 to register all IMFS patients in Canada. Analysis was restricted to patients diagnosed after November 30, 1997. Summary statistics were used to depict the study population while survival was described using the Kaplan-Meier method. RESULTS: 74 CIMFR patients were considered recently diagnosed. Median age at diagnosis was 2.7 years (range, birth to 40.6). Annual follow-up data were available for 53 (72%) patients. The five most prevalent diagnoses were Fanconi anemia (FA), Shwachman-Diamond syndrome (SDS), Diamond-Blackfan anemia (DBA), dyskeratosis congenita (DKC), and Kostmann's neutropenia (KS). Eighteen (24%) patients were unclassifiable. Twenty-eight (53%) follow-up patients had disease progression as indicated by new or worsening cytopenias, new marrow changes, or initiation of transfusion support and/or medical therapy. Fourteen (19%) fulfilled minimal diagnostic criteria for myelodysplasia. Eleven patients had hematopoietic stem cell transplantation (HSCT) by first follow-up. Five patients have died. Survival at 36 months is 89.8 +/- 5.7%. CONCLUSIONS: IMFS patients are often diagnosed at a young age. The relative distribution of diagnoses is similar to previous reviews of published cases; however, 25% of patients are currently unclassifiable. Disease progression has occurred in approximately 50% of follow-up patients. Early mortality is noted. Continued prospective observation of these patients is warranted.

Prediction of specific absorption rate in mother and fetus associated with MRI examinations during pregnancy.

There is uncertainty regarding the risk posed by magnetic resonance imaging (MRI) examinations to pregnant patients. The most frequently used methods, such as single-shot fast spin echo (ssFSE), often require operation at the specific absorption rate (SAR) limits imposed by safety guidelines. With the introduction of higher-field systems, such limits will be even more significant for fetal imaging. An electromagnetic solver based on the time domain finite integration technique (FIT) was used to predict SAR in an anatomically realistic model of a pregnant patient (28 weeks' gestation) associated with the radiofrequency (RF) fields from birdcage body coils typical of 1.5 T and 3 T MRI systems (i.e., operating at approximately 64 and 127 MHz, respectively). The results suggest that 1) the highest local SAR is in the mother, with the fetus being exposed to a peak of approximately 40-60% of that value at 64 MHz, increasing to approximately 50-70% at 127 MHz; 2) compliance with U.S. Food and Drug Administration (FDA) and International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines requires control of SAR values averaged over 1 g or 10 g of tissue, respectively; and 3) compliance with Medical Device Agency (MDA) guidelines requires control of the maximum SAR(10g) within the fetus.

Treatment of intracranial and extracranial haemorrhages in a neonate with severe haemophilia B with recombinant factor IX infusion.

Intracranial (ICH) and extracranial (ECH) haemorrhages are potentially life-threatening events that may occur comorbidly in neonates with haemophilia. There is little data on the use of recombinant factor IX (rFIX; BeneFIX in the neonate. Children <15 years of age are known to require higher doses of recombinant Factor IX (FIX) than older persons, which raises specific concerns in the neonate due to the increased risk of thrombosis in this age group (Thromb Haemost 2002; 87: 431). This report describes a case in which a high rate of continuous infusion of recombinant FIX was used to treat a newborn with significant intracranial and subgaleal haemorrhages. A high rate of infusion maintained at 30-35 U kg(-1) h(-1) was necessary to maintain adequate FIX levels. Despite the high rate of continuous infusion, no adverse events were noted. Our patient had a rare genetic mutation causing severe haemophilia B. A neonate with severe haemophilia B was treated successfully with recombinant FIX through continuous infusion. A high rate of infusion was required and no complications were noted.