Fine particle pollution during megafires contains potentially toxic elements

Wildfires that raged across Australia during the 2019-2020 'Black Summer' produced an enormous quantity of particulate matter (PM) pollution, with plumes that cloaked many urban centres and ecosystems along the eastern seaboard. This has motivated a need to understand the magnitude and nature of PM exposure, so that its impact on both built and natural environments can be more accurately assessed. Here we present the potentially toxic fingerprint of PM captured by building heating, ventilation, and air conditioning filters in Sydney, Australia during the peak of the Wildfires, and from ambient urban emissions one year later (Reference period). Atmospheric PM and meteorological monitoring data were also assessed to determine the magnitude and source of high PM exposure. The wildfires were a major source of PM pollution in Sydney, exceeding the national standards on 19 % of days between November-February. Wildfire particles were finer and more spherical compared to Reference PM, with count median diameters of 892.1 ± 23.1 versus 1484.8 ± 96.7 nm (mean ± standard error). On an equal-mass basis, differences in potentially toxic elements were predominantly due to higher SO42--S (median 20.4 vs 4.7 mg g-1) and NO3--N (2.4 vs 1.2 mg g-1) in Wildfire PM, and higher PO43--P (10.4 vs 1.4 mg g-1) in Reference PM. Concentrations of remaining elements were similar or lower than Reference PM, except for enrichments to F-, Cl-, dissolved Mn, and particulate Mn, Co and Sb. Fractional solubilities of trace elements were similar or lower than Reference PM, except for enhanced Hg (12.1 vs 1.0 %) and greater variability in Cd, Hg and Mn solubility, which displayed upper quartiles exceeding that of Reference PM. These findings contribute to our understanding of human and ecosystem exposures to the toxic components of mixed smoke plumes, especially in regions downwind of the source.

The interaction between neuromuscular forces, aerodynamic forces, and anatomical motion in the upper airway predicts the severity of pediatric OSA

Upper airway neuromuscular response to air pressure during inhalation is an important factor in assessing pediatric subjects with obstructive sleep apnea (OSA). The neuromuscular response's strength, timing, and duration all contribute to the potential for airway collapses and the severity of OSA. This study quantifies these factors at the soft palate, tongue, and epiglottis to assess the relationship between neuromuscular control and OSA severity in 20 pediatric subjects with and without trisomy 21, under dexmedetomidine-induced sedation. The interaction between neuromuscular force and airflow pressure force was assessed based on power transferred between the airway wall and airflow calculated from airway wall motion (from cine magnetic resonance images) and air pressure acting on the airway wall (from computational fluid dynamics simulations). Airway wall motion could be asynchronous with pressure forces due to neuromuscular activation, or synchronous with pressure forces, indicating a passive response to airflow. The obstructive apnea-hypopnea index (oAHI) quantified OSA severity. During inhalation, the normalized work done through asynchronous dilation of the airway at the soft palate, tongue, and epiglottis correlated significantly with oAHI (Spearman's ρ = 0.54, 0.50, 0.64; P = 0.03, 0.03, 0.003). Synchronous collapse at the epiglottis correlated significantly with oAHI (ρ = 0.52; P = 0.02). Temporal order of synchronous and asynchronous epiglottis motion during inhalation predicted the severity of OSA (moderate vs. severe) with 100% sensitivity and 70% specificity. Subjects with severe OSA and/or trisomy 21 have insufficient neuromuscular activation during inhalation, leading to collapse and increased neuromuscular activation. Airflow-driven airway wall motion during late inhalation likely is the main determinant of OSA severity.NEW & NOTEWORTHY This is the first study that combines cine MRI and computational fluid dynamics with in vivo synchronous respiratory flow measurement to quantify the interaction between airway neuromuscular forces, aerodynamic forces, and airway anatomy noninvasively in pediatric patients with obstructive sleep apnea (OSA). The results indicate power transfer predicts OSA severity.

Fuelling phytoremediation: gasoline degradation by green wall systems-a case study

The capacity for indoor plants including green wall systems to remove specific volatile organic compounds (VOCs) is well documented in the literature; however under realistic settings, indoor occupants are exposed to a complex mixture of harmful compounds sourced from various emission sources. Gasoline vapour is one of the key sources of these emissions, with several studies demonstrating that indoor occupants in areas surrounding gasoline stations or with residentially attached garages are exposed to far higher concentrations of harmful VOCs. Here we assess the potential of a commercial small passive green wall system, commercially named the 'LivePicture Go' from Ambius P/L, Australia, to drawdown VOCs that comprise gasoline vapour, including total VOC (TVOC) removal and specific removal of individual speciated VOCs over time. An 8-h TVOC removal efficiency of 42.45% was achieved, along with the complete removal of eicosane, 1,2,3-trimethyl-benzene, and hexadecane. Further, the green wall also effectively reduced concentrations of a range of harmful benzene derivatives and other VOCs. These results demonstrate the potential of botanical systems to simultaneously remove a wide variety of VOCs, although future research is needed to improve upon and ensure efficiency of these systems over time and within practical applications.

Nanoscale LiZnN - Luminescent Half-Heusler Quantum Dots

Colloidal semiconductor quantum dots are a well-established technology, with numerous materials available either commercially or through the vast body of literature. The prevalent materials are cadmium-based and are unlikely to find general acceptance in most applications. While the III-V family of materials is a likely substitute, issues remain about its long-term suitability, and other earth-abundant materials are being explored. In this report, we highlight a nanoscale half-Heusler semiconductor, LiZnN, composed of readily available elements as a potential alternative system to luminescent II-VI and III-V nanoparticle quantum dots.

Sleep Endoscopy and Cine Magnetic Resonance Imaging Evaluation of Children With Persistent Obstructive Sleep Apnea

OBJECTIVE

To compare findings of same-day cine magnetic resonance imaging (MRI) and drug-induced sleep endoscopy (DISE) and examine how each technique uniquely contributes to the evaluation of persistent obstructive sleep apnea following adenotonsillectomy.

STUDY DESIGN

Retrospective cohort study.

SETTING

Quaternary care center.

METHODS

Chart review was performed for consecutive patients who underwent same-day cine MRI and DISE between 2015 and 2020. Descriptive statistics are reported, and Cohen kappa coefficients were calculated to evaluate the agreement between cine MRI and DISE for obstruction at the adenoids, lingual tonsils, and tongue base.

RESULTS

There were 137 patients, the mean age was 10.4 years (95% CI, 3.2-16.7), and 62.8% were male. The most common sites of obstruction on DISE were the tongue base (86.9%), velum (78.7%), epiglottis (74.5%), inferior turbinate (68.6%), and lingual tonsil (61.3%). The most common sites of obstruction on cine MRI were the hypopharynx (56.3%), tongue base (44.8%), lingual tonsil (38.0%), and macroglossia (37.6%). There was moderate agreement for adenoid hypertrophy (κ = 0.53) and poor agreement for lingual tonsil hypertrophy (κ = 0.15) and tongue base obstruction (κ = 0.09). DISE identified more instances of multilevel obstruction when compared with cine MRI (94.9% vs 48.2%).

CONCLUSION

DISE offered a better examination of nasal and supraglottic obstruction and is sensitive to partial vs complete collapse, while cine MRI offered better soft tissue resolution for lymphoid tissue hypertrophy and provided a global view of primary and secondary airway obstruction. Cine MRI and DISE are complementary modalities in the evaluation of children with persistent obstructive sleep apnea.

Phytoremediation for the indoor environment: a state-of-the-art review

Poor indoor air quality has become of particular concern within the built environment due to the time people spend indoors, and the associated health burden. Volatile organic compounds (VOCs) off-gassing from synthetic materials, nitrogen dioxide and harmful outdoor VOCs such benzene, toluene, ethyl-benzene and xylene penetrate into the indoor environment through ventilation and are the main contributors to poor indoor air quality with health effects. A considerable body of literature over the last four decades has demonstrate the removal of gaseous contaminants through phytoremediation, a technology that relies on plant material and technologies to remediate contaminated air streams. In this review we present a state-of-the-art on indoor phytoremediation over the last decade. Here we present a review of 38 research articles on both active and passive phytoremediation, and describe the specific chemical removal efficiency of different systems. The literature clearly indicates the efficacy of these systems for the removal of gaseous contaminants in the indoor environment, however it is evident that the application of phytoremediation technologies for research purposes in-situ is currently significantly under studied. In addition, it is common for research studies to assess the removal of single chemical species under controlled conditions, with little relevancy to real-world settings easily concluded. The authors therefore recommend that future phytoremediation research be conducted both in-situ and on chemical sources of a mixed nature, such as those experienced in the urban environment like petroleum vapour, vehicle emissions, and mixed synthetic furnishings off-gassing. The assessment of these systems both in static chambers for their theoretical performance, and in-situ for these mixed chemical sources is essential for the progression of this research field and the widespread adoption of this technology.

Computational assessment of upper airway muscular activity in obstructive sleep apnea - In vitro validation

Neuromuscular control of the upper airway contributes to obstructive sleep apnea (OSA). An accurate, non-invasive method to assess neuromuscular function is needed to improve surgical treatment outcomes. Currently, surgical approaches for OSA are based on airway anatomy and are often not curative. When the airway surface moves, the power transferred between air in the airway lumen and the structures of the upper airway may be a measure of airway neuromuscular activity. The aim of this study was to validate power transfer as a measure of externally applied forces, representing neuromuscular activity, through cine computed tomography (CT) imaging and computational fluid dynamics (CFD) analysis in a 3D-printed airway model. A hollow elastic airway model was manufactured. An insufflation/exsufflation device generated airflow within the model lumen. The model was contained in an airtight chamber that could be positively or negatively pressurized to represent muscular forces. These forces were systematically applied to dilate and collapse the model. Cine CT imaging captured airway wall movement during respiratory cycles with and without externally applied forces. Power transfer was calculated from the product of wall movement and internal aerodynamic pressure forces using CFD simulations. Cross-correlation peaks between power transfer and changes in externally applied pressure during exhalation and inhalation were -0.79 and 0.95, respectively. Power transfer calculated via cine CT imaging and CFD was an accurate surrogate measure of externally applied forces representing airway muscular activity. In the future, power transfer may be used in clinical practice to phenotype patients with OSA and select personalized therapies.

The botanical biofiltration of volatile organic compounds and particulate matter derived from cigarette smoke

Despite the growing use of control measures, environmental tobacco smoke (ETS) remains a significant pollutant source in indoor air in many areas of the world. Current control methods for reducing ETS exposure are inadequate to protect public health in environments where cigarettes are smoked. An alternative solution is botanical biofiltration which has previously been shown to lower concentrations of volatile organic compounds (VOCs) and particulate matter (PM) from a range of polluted air streams. This study is the first to assess the potential of a botanical biofilter with the species Spathiphyllum wallisii (Peace Lily) for the removal of cigarette-derived VOCs and all size fractions of PM. Single pass removal efficiencies of 43.26% for total VOCs and 34.37% for total suspended particles were achieved. The botanical biofilter reduced the concentrations of a range of harmful ETS chemicals including nicotine, limonene, and toluene. Evaluation of the re-emission of ETS constituents filtered by the botanical biofilter revealed no particle resuspension or off gassing. The results demonstrate the potential of botanical biofilters to reduce public ETS exposure, although further research is needed to improve upon and ensure the efficiency of these systems for practical applications.

Predictability of thermal fluctuations influences functional traits of a cosmopolitan marine diatom

Evolutionary theory predicts that organismal plasticity should evolve in environments that fluctuate regularly. However, in environments that fluctuate less predictably, plasticity may be constrained because environmental cues become less reliable for expressing the optimum phenotype. Here, we examine how the predictability of +5°C temperature fluctuations impacts the phenotype of the marine diatom Thalassiosira pseudonana. Thermal regimes were informed by temperatures experienced by microbes in an ocean simulation and featured regular or irregular temporal sequences of fluctuations that induced mild physiological stress. Physiological traits (growth, cell size, complexity and pigmentation) were quantified at the individual cell level using flow cytometry. Changes in cellular complexity emerged as the first impact of predictability after only 8–11 days, followed by deleterious impacts on growth on days 13–16. Specifically, cells with a history of irregular fluctuation exposure exhibited a 50% reduction in growth compared with the stable reference environment, while growth was 3–18 times higher when fluctuations were regular. We observed no evidence of heat hardening (increasingly positive growth) with recurrent fluctuations. This study demonstrates that unpredictable temperature fluctuations impact this cosmopolitan diatom under ecologically relevant time frames, suggesting shifts in environmental stochasticity under a changing climate could have widespread consequences among ocean primary producers.

Predicting critical closing pressure in children with obstructive sleep apnea using fluid-structure interaction

Surgical treatment of obstructive sleep apnea (OSA) in children requires knowledge of upper airway dynamics, including the closing pressure (Pcrit), a measure of airway collapsibility. We applied a flow-structure interaction (FSI) computational model to estimate Pcrit in patient-specific upper airway models obtained from magnetic resonance imaging (MRI) scans. We sought to examine the agreement between measured and estimated Pcrit from FSI models in children with Down syndrome. We hypothesized that the estimated Pcrit would accurately reflect measured Pcrit during sleep and therefore reflect the severity of OSA as measured by the obstructive apnea-hypopnea index (AHI). All participants (n = 41) underwent polysomnography and sedated sleep MRI scans. We used Bland-Altman plots to examine the agreement between measured and estimated Pcrit. We determined associations between estimated Pcrit and OSA severity, as measured by AHI, using regression models. The agreement between passive and estimated Pcrit showed a fixed bias of -1.31 [confidence interval (CI) = -2.78, 0.15] and a nonsignificant proportional bias. A weaker agreement with active Pcrit was observed. A model including AHI, gender, an interaction term for AHI, and gender and neck circumference explained the largest variation (R2 = 0.61) in the relationship between AHI and estimated Pcrit (P < 0.0001). Overlap between the areas of the airway with the lowest stiffness, and areas of collapse on dynamic MRI, was 77.4 ± 30% for the nasopharyngeal region and 78.6 ± 33% for the retroglossal region. The agreement between measured and estimated Pcrit and the significant association with AHI supports the validity of Pcrit estimates from the FSI model.NEW & NOTEWORTHY We present a noninvasive method for estimating critical closing pressure (Pcrit) using fluid-structure interaction (FSI) simulations and magnetic resonance imaging (MRI) scans in patients with obstructive sleep apnea (OSA). We used patient-specific stiffness measures in our FSI model to account for any individual variability in the elasticity of soft tissues surrounding the upper airway. We validated this model by measuring the degree of agreement between measured and estimated Pcrit.

Effective reduction of roadside air pollution with botanical biofiltration

Currently no sustainable, economical and scalable systems have been developed for the direct removal of roadside air pollutants at their source. Here we present a simple and effective air filtering technology: botanical biofiltration, and the first field assessment of three different botanical biofilter designs for the filtration of traffic associated air pollutants - NO₂, O₃ and PM_2.5 - from roadside ambient air in Sydney, Australia. Over two six month research campaigns, we show that all of the tested systems filtered NO₂, O₃ and PM_2.5 with average single pass removal efficiencies of up to 71.5%, 28.1% and 22.1% respectively. Clean air delivery rates of up to 121 m³/h, 50 m³/h and 40 m³/h per m² of active green wall biofilter were achieved for the three pollutants respectively, with pollutant removal efficiency positively correlated with their ambient concentrations. We propose that large scale field trials of this technology are warranted to promote sustainable urban development and improved public health outcomes.

Critical care usage after major gastrointestinal and liver surgery: a prospective, multicentre observational study

BACKGROUND

Patient selection for critical care admission must balance patient safety with optimal resource allocation. This study aimed to determine the relationship between critical care admission, and postoperative mortality after abdominal surgery.

METHODS

This prespecified secondary analysis of a multicentre, prospective, observational study included consecutive patients enrolled in the DISCOVER study from UK and Republic of Ireland undergoing major gastrointestinal and liver surgery between October and December 2014. The primary outcome was 30-day mortality. Multivariate logistic regression was used to explore associations between critical care admission (planned and unplanned) and mortality, and inter-centre variation in critical care admission after emergency laparotomy.

RESULTS

Of 4529 patients included, 37.8% (n=1713) underwent planned critical care admissions from theatre. Some 3.1% (n=86/2816) admitted to ward-level care subsequently underwent unplanned critical care admission. Overall 30-day mortality was 2.9% (n=133/4519), and the risk-adjusted association between 30-day mortality and critical care admission was higher in unplanned [odds ratio (OR): 8.65, 95% confidence interval (CI): 3.51-19.97) than planned admissions (OR: 2.32, 95% CI: 1.43-3.85). Some 26.7% of patients (n=1210/4529) underwent emergency laparotomies. After adjustment, 49.3% (95% CI: 46.8-51.9%, P<0.001) were predicted to have planned critical care admissions, with 7% (n=10/145) of centres outside the 95% CI.

CONCLUSIONS

After risk adjustment, no 30-day survival benefit was identified for either planned or unplanned postoperative admissions to critical care within this cohort. This likely represents appropriate admission of the highest-risk patients. Planned admissions in selected, intermediate-risk patients may present a strategy to mitigate the risk of unplanned admission. Substantial inter-centre variation exists in planned critical care admissions after emergency laparotomies.

Import of community-associated, methicillin-resistant Staphylococcus aureus to Europe through skin and soft-tissue infection in intercontinental travellers, 2011-2016

OBJECTIVES

Recently, following import by travel and migration, epidemic community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has caused nosocomial outbreaks in Europe, sometimes with a fatal outcome. We describe clinico-epidemiological characteristics of CA-MRSA detected by the European Network for the Surveillance of imported S. aureus (www.staphtrav.eu) from May 2011 to November 2016.

METHODS

Sentinel surveillance at 13 travel clinics enrolling patients with travel-associated skin and soft-tissue infection (SSTI) and analysing lesion and nose swabs at one central laboratory.

RESULTS

A total of 564 independent case-patients with SSTI were enrolled and had 374 (67%) S. aureus-positive lesions, of which 14% (51/374) were MRSA. The majority of CA-MRSA isolates from SSTI were Panton-Valentine leucocidin (PVL) -positive (43/51, 84%). The risk of methicillin-resistance in imported S. aureus varied by travel region (p <0.001) and was highest in Latin America (16/57, 28%, 95% CI 17.0-41.5) and lowest in Sub-Saharan Africa (4/121, 3%, 95% CI 0.9-8.3). Major epidemic clones (USA300 / USA300 Latin-American Variant, Bengal Bay, South Pacific) accounted for more than one-third (19/51, 37%) of CA-MRSA imports. CA-MRSA SSTI in returnees was complicated (31/51 multiple lesions, 61%; 22/50 recurrences, 44%), led to health-care contact (22/51 surgical drainage, 43%; 7/50 hospitalization, 14%), was transmissible (13/47 reported similar SSTI in non-travelling contacts, 28%), and associated with S. aureus nasal colonization (28 of 51 CA-MRSA cases, 55%; 24 of 28 colonized with identical spa-type in nose and lesion, 85%).

CONCLUSIONS

Travel-associated CA-MRSA SSTI is a transmissible condition that leads to medical consultations and colonization of the infected host.

[Chronic skin ulcer in a 24-year-old man after a journey to Southeast Asia]

Our report concerns a 24-year-old man with a chronic exsudative skin lesion after a journey to Southeast Asia. The diagnosis of melioidosis was made by the identification of Burkholderia pseudomallei from the ichor. The diagnosis was confirmed by polymerase change reaction. The patient was treated with meropenem i. v. for about 10 days and with trimethoprim/sulfamethoxazole for the following 12 weeks. Melioidosis is an endemic disease in Southeast Asia and North Australia which in some cases can run a severe course and can have a high fatality rate. The relevance of melioidosis becomes more important against the background of the increasing global movement of travelers and migration.

Upper Airway Reflexes are Preserved During Dexmedetomidine Sedation in Children With Down Syndrome and Obstructive Sleep Apnea

STUDY OBJECTIVES

The assessment of pharyngeal collapsibility is difficult to perform in children under normal sleep. An alternative is to perform the assessment under an anesthetic, such as dexmedetomidine (DEX), that induces non-rapid eye movement (NREM) sleep. The objectives of this study were to compare critical closing airway pressure (Pcrit) obtained during natural sleep to that obtained under DEX in patients with Down syndrome (DS) and persistent obstructive sleep apnea (OSA) and determine whether Pcrit measured under sedation predicts the severity of OSA.

METHODS

The passive and active Pcrit, which represent airway passive mechanical properties and active dynamic responses to airway obstruction, respectively, were measured. Upper airway reflex activity was estimated by calculating the difference between active and passive Pcrit. Subjects underwent overnight polysomnography during which Pcrit was measured during normal sleep. Pcrit was also measured during DEX sedation at a dose of 2 μg/kg/h.

RESULTS

The study included 50 patients with median age of 11.4 years (interquartile range: 7.0-13.9) and median body mass index of 23.0 kg/m² (interquartile range: 18.4-29.1), 66% male and 80% Caucasian. Passive Pcrit was significantly higher than active Pcrit when measured during normal sleep and DEX-induced sleep. There was a positive association between apnea-hypopnea index and passive Pcrit (Spearman r = 0.53, P = .0001) and active Pcrit (r = 0.55, P = .0002) under DEX-induced sleep. There were no significant differences between the Pcrit measurements during natural sleep and during DEX sedation.

CONCLUSION

Patients with OSA can compensate for airway obstruction under DEX-induced sleep. The close association between Pcrit and apnea-hypopnea index suggests that airway responses with DEX sedation parallel those seen during natural sleep.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT01902407.

The Biosynthesis of Infrared-Emitting Quantum Dots in Allium Fistulosum

The development of simple routes to emissive solid-state materials is of paramount interest, and in this report we describe the biosynthesis of infrared emitting quantum dots in a living plant via a mutual antagonistic reaction. Exposure of common Allium fistulosum to mercury and tellurium salts under ambient conditions resulted in the expulsion of crystalline, non-passivated HgTe quantum dots that exhibited emissive characteristics in the near-infrared spectral region, a wavelength range that is important in telecommunications and solar energy conversion.

Upper airway morphology in Down Syndrome patients under dexmedetomidine sedation

BACKGROUND AND OBJECTIVES

Children with Down Syndrome are vulnerable to significant upper airway obstruction due to relative macroglossia and dynamic airway collapse. The objective of this study was to compare the upper airway dimensions of children with Down Syndrome and obstructive sleep apnea with normal airway under dexmedetomidine sedation.

METHODS

IRB approval was obtained. In this retrospective study, clinically indicated dynamic sagittal midline magnetic resonance images of the upper airway were obtained under low (1mcg/kg/h) and high (3mcg/kg/h) dose dexmedetomidine. Airway anteroposterior diameters and sectional areas were measured as minimum and maximum dimensions by two independent observers at soft palate (nasopharyngeal airway) and at base of the tongue (retroglossal airway).

RESULTS AND CONCLUSIONS

Minimum anteroposterior diameter and minimum sectional area at nasopharynx and retroglossal airway were significantly reduced in Down Syndrome compared to normal airway at both low and high dose dexmedetomidine. However, there were no significant differences between low and high dose dexmedetomidine in both Down Syndrome and normal airway. The mean apnea hypopnea index in Down Syndrome was 16±11. Under dexmedetomidine sedation, children with Down Syndrome and obstructive sleep apnea when compared to normal airway children show significant reductions in airway dimensions most pronounced at the narrowest points in the nasopharyngeal and retroglossal airways.

Predominance of dfrG as determinant of trimethoprim resistance in imported Staphylococcus aureus

To investigate the global occurrence of trimethoprim-sulfamethoxazole resistance and the genetic mechanisms of trimethoprim resistance, we analysed Staphylococcus aureus from travel-associated skin and soft-tissue infections treated at 13 travel clinics in Europe. Thirty-eight per cent (75/196) were trimethoprim-resistant and 21% (41/196) were resistant to trimethoprim-sulfamethoxazole. Among methicillin-resistant S. aureus, these proportions were 30% (7/23) and 17% (4/23), respectively. DfrG explained 92% (69/75) of all trimethoprim resistance in S. aureus. Travel to South Asia was associated with the highest risk of acquiring trimethoprim-sulfamethoxazole-resistant S. aureus. We conclude that globally dfrG is the predominant determinant of trimethoprim resistance in human S. aureus infection.

Idiopathic Facial Aseptic Granuloma: Review of an Evolving Clinical Entity

Idiopathic facial aseptic granuloma (IFAG), originally termed pyodermite froide du visage, describes a generally asymptomatic facial nodule presenting in childhood with clinical resemblance to pyoderma or cystic, granulomatous, or vascular lesions. Clinical understanding is constantly evolving, with recent observations indicating that IFAG may represent a subtype of childhood rosacea. We present a case of IFAG associated with eyelid chalazions in a 19-month-old boy. Although his clinical course paralleled previously reported IFAG cases, we observed a unique ultrasound variation during initial diagnostic examination. Further delineation of clinical, imaging, and histologic properties of IFAG may reveal insights into etiologic associations and ideal management.

Skin and soft tissue infections in intercontinental travellers and the import of multi-resistant Staphylococcus aureus to Europe

Staphylococcus aureus is emerging globally. Treatment of infections is complicated by increasing antibiotic resistance. We collected clinical data and swabs of returnees with skin and soft tissue infections (SSTI) at 13 travel-clinics in Europe (www.staphtrav.eu). Sixty-two percent (196/318) SSTI patients had S. aureus-positive lesions, of which almost two-thirds (122/196) were Panton-Valentine leukocidin (PVL) positive. PVL was associated with disease severity, including hospitalization for SSTI (OR 5.2, 95% CI 1.5-18.2). In returnees with SSTI, longer travel and more intense population contact were risk factors for nasal colonization with PVL-positive S. aureus. Imported S. aureus frequently proved resistant to trimethoprim-sulfamethoxazole (21%), erythromycin (21%), tetracycline (20%), ciprofloxacin (13%), methicillin (12%) and clindamycin (8%). Place of exposure was significantly (p < 0.05) associated with predominant resistance phenotypes and spa genotypes: Latin America (methicillin; t008/CC24/304), Africa (tetracycline, trimethoprim-sulfamethoxazole; t084/CC84, t314/singleton, t355/CC355), South Asia (trimethoprim-sulfamethoxazole, ciprofloxacin; t021/CC21/318), South-East Asia (clindamycin; t159/CC272). USA300-like isolates accounted for 30% of all methicillin-resistant S. aureus imported to Europe and were predominantly (71%) acquired in Latin America. Multi-resistance to non-β-lactams were present in 24% of imports and associated with travel to South Asia (ORcrude 5.3, 95% CI 2.4-11.8), even after adjusting for confounding by genotype (ORadjusted 3.8, 95% 1.5-9.5). Choosing randomly from compounds recommended for the empiric treatment of severe S. aureus SSTI, 15% of cases would have received ineffective antimicrobial therapy. These findings call for the development of regionally stratified guidance on the antibiotic management of severe imported S. aureus disease and put the infected and colonized traveller at the centre of interventions against the global spread of multi-resistant S. aureus.

Detection of progressive cardiac dysfunction by serial evaluation of circumferential strain in patients with Duchenne muscular dystrophy

The present study evaluated progressive cardiac dysfunction using serial circumferential strain (epsilon(cc)) measurements in patients with Duchenne muscular dystrophy (DMD). DMD is characterized by progressive cardiac dysfunction and myocardial fibrosis late in the disease process. We hypothesized that serial epsilon(cc) changes could be detected in individual patients with DMD during a time when the left ventricular ejection fraction (EF) changes are insignificant. Cardiac magnetic resonance imaging data from patients with DMD were evaluated. The left ventricular EF was calculated from steady-state free precession cine images and the composite epsilon(cc) measurement from tagged cine images. The serial epsilon(cc) and EF values for each patient were analyzed using the Wilcoxon sign rank test. Data from 51 patients with DMD (2 studies per patient, mean age at the initial study 11.8 +/- 3.5 years, range 7.4 to 25.4) were analyzed, with a mean interval between cardiac magnetic resonance studies of 15.6 +/- 6.0 months (range 6.2 to 28.1). In the interval between studies, the epsilon(cc) had decreased in all patients with DMD. The average decrease was 1.8 +/- 1.3 (p <0.001). However, the EF had decreased in 33 of the 51 patients and had increased in 18 of the 51 patients. On average, the EF decreased by 2.9 +/- 8.57% (p = NS). In conclusion, in patients with DMD, epsilon(cc) abnormalities indicate progression within a relatively short period when the EF changes were not significant. Serial epsilon(cc) measurements might provide reliable monitoring of the progression of DMD-associated cardiac dysfunction before overt heart failure develops, because it is more sensitive than the EF.

Comparison of magnetic resonance feature tracking for strain calculation with harmonic phase imaging analysis

OBJECTIVES

To compare a steady-state free precession cine sequence-based technique (feature tracking [FT]) to tagged harmonic phase (HARP) analysis for peak average circumferential myocardial strain (epsilon(cc)) analysis in a large and heterogeneous population of boys with Duchenne muscular dystrophy (DMD).

BACKGROUND

Current epsilon(cc) assessment techniques require cardiac magnetic resonance-tagged imaging sequences, and their analysis is complex. The FT method can readily be performed on standard cine (steady-state free precession) sequences.

METHODS

We compared mid-left ventricular whole-slice epsilon(cc) by the 2 techniques in 191 DMD patients grouped according to age and severity of cardiac dysfunction: group B: DMD patients 10 years and younger with normal ejection fraction (EF); group C: DMD patients older than 10 years with normal EF; group D: DMD patients older than 10 years with reduced EF but negative myocardial delayed enhancement (MDE); group E: DMD patients older than 10 years with reduced EF and positive MDE; and group A: 42 control subjects. Retrospective, offline analysis was performed on matched tagged and steady-state free precession slices.

RESULTS

For the entire study population (N = 233), mean FT epsilon(cc) values (-13.3 +/- 3.8%) were highly correlated with HARP epsilon(cc) values (-13.6 +/- 3.4%), with a Pearson correlation coefficient of 0.899. The mean epsilon(cc) of DMD patients determined by HARP (-12.52 +/- 2.69%) and FT (-12.16 +/- 3.12%) was not significantly different (p = NS). Similarly, the mean epsilon(cc) of the control subjects by determined HARP (-18.85 +/- 1.86) and FT (-18.81 +/- 1.83) was not significantly different (p = NS). Excellent correlation between the 2 methods was found among subgroups A through E, except there was no significant difference in strain between groups B and C with FT analysis.

CONCLUSIONS

FT-based assessment of epsilon(cc) correlates highly with epsilon(cc) derived from tagged images in a large DMD patient population with a wide range of cardiac dysfunction and can be performed without additional imaging.

Left ventricular T2 distribution in Duchenne muscular dystrophy

BACKGROUND

Although previous studies have helped define the natural history of Duchenne muscular dystrophy (DMD)-associated cardiomyopathy, the myocardial pathobiology associated with functional impairment in DMD is not yet known.The objective of this study was to assess the distribution of transverse relaxation time (T2) in the left ventricle (LV) of DMD patients, and to determine the association of myocardial T2 heterogeneity to the severity of cardiac dysfunction. DMD patients (n = 26) and normal control subjects (n = 13) were studied by cardiovascular magnetic resonance (CMR). DMD subject data was stratified based on subject age and LV ejection fraction (EF) into the following groups: A (<12 years old, n = 12); B (>or=12 years old, EF or=12 years old, EF = 55%, n = 6). Controls were also stratified by age into Groups N1 (<12 years, n = 6) and N2 (>12 years, n = 5). LV mid-slice circumferential myocardial strain (epsilon cc) was calculated using tagged CMR imaging. T2 maps of the LV were generated for all subjects using a black blood dual spin echo method at two echo times. The full width at half maximum (FWHM) was calculated from a histogram of LV T2 distribution constructed for each subject.

RESULTS

In DMD subject groups, FWHM of the T2 histogram rose progressively with age and decreasing EF (Group A FWHM= 25.3 +/- 3.8 ms; Group B FWHM= 30.9 +/- 5.3 ms; Group C FWHM= 33.0 +/- 6.4 ms). Further, FWHM was significantly higher in those with reduced circumferential strain (|epsilon cc| 12% (Group A). Group A FWHM was not different from the two normal groups (N1 FWHM = 25.3 +/- 3.5 ms; N2 FWHM= 24.0 +/- 7.3 ms).

CONCLUSION

Reduced EF and epsilon cc correlates well with increased T2 heterogeneity quantified by FWHM, indicating that subclinical functional impairments could be associated with pre-existing abnormalities in tissue structure in young DMD patients.

Transient hepatic attenuation differences in neonates

BACKGROUND

A transient hepatic attenuation difference (THAD) is a hepatic perfusion anomaly seen on contrast-enhanced CT scans caused by an alteration in the dual blood supply of the liver. Although THADs have been described in adolescents and adults, they have not previously been described in neonates.

OBJECTIVE

We describe the appearance and evaluate the frequency of THADs in neonates < or =1 month of age compared to other infants younger than 2 years.

MATERIALS AND METHODS

A retrospective study was performed looking at all CT angiograms from 2000 to 2007 in infants <2 years of age. The incidence of THADs was compared among four age groups. Significance was determined using a logistic regression model.

RESULTS

The study included 128 CT angiograms. A THAD was seen in 9/26 infants <1 month of age, in 3/50 infants 1 to 6 months of age, in 1/23 infants 6 months to 1 year of age, and in 1/29 infants 1 to 2 years of age. A THAD was found significantly more frequently in infants <1 month of age than in the older age groups (P<0.05).

CONCLUSION

THADs are benign entities that can be seen normally in the neonatal age group. When the characteristic appearance is seen on CT, no further imaging is needed.

Circumferential strain analysis identifies strata of cardiomyopathy in Duchenne muscular dystrophy: a cardiac magnetic resonance tagging study

OBJECTIVES

This study sought to evaluate the natural history of occult cardiac dysfunction in Duchenne muscular dystrophy (DMD).

BACKGROUND

Duchenne muscular dystrophy is characterized by progressive cardiac dysfunction and myocardial fibrosis late in the disease process. We hypothesized that left ventricular myocardial peak circumferential strain (epsilon(cc)) would decrease in DMD before global systolic functional abnormalities regardless of age or ventricular ejection fraction (EF).

METHODS

We evaluated cardiac magnetic resonance image (MRI) data from 70 DMD patients and 16 aged-matched control subjects. Standard imaging data included steady-state free precession short-axis cine stack images, cine myocardial tagged images, and myocardial delayed enhancement (MDE) (an indicator of myocardial fibrosis) sequences. Analysis was performed with QMASS (Medis Medical Imaging Systems, Leiden, the Netherlands) and HARP (Diagnosoft, Palo Alto, California) software. The DMD patient data were subdivided by age (<10 or >10 years), EF (>55% or <55%), and the presence or absence of MDE.

RESULTS

The DMD patients with normal EF had reduced epsilon(cc) at an early age (<10 years) compared with control subjects (p < 0.01). The DMD patients age >10 years with normal EF had further decline in epsilon(cc) compared with younger DMD patients (p < 0.01). There was further decline in epsilon(cc) with age in patients with reduced EF (p < 0.01) without MDE. The oldest patients, with both reduced EF and positive MDE, exhibited the lowest epsilon(cc). None of the patients had ventricular hypertrophy.

CONCLUSIONS

Myocardial strain abnormalities are prevalent in young DMD patients despite normal EF, and these strain values continue to decline with advancing age. Strain analysis in combination with standard MRI and MDE imaging provides a means to stratify DMD cardiomyopathy.

Frequency scouting for cardiac imaging with SSFP at 3 Tesla

Steady-state free precision techniques are often used in cine cardiac MRI, but are highly susceptible to off-resonance artifacts. In this article, we review the types and prevalence of off-resonance artifacts in the left ventricle on a 3 T MR scanner and describe the implementation of a technique to mitigate these artifacts. A group of 16 healthy children underwent SSFP cine imaging in the short axis. The synthesizer frequency was adjusted after scouting for the optimal frequency in a series of SSFP images with different frequency shifts. A total of 136 short-axis slices were examined for artifacts after the frequency adjustment. A significant number of slices in the apex region contained dark bands, flow artifacts and/or bright out-of-plane coherent artifacts. However, only five slices (3.6%) had artifacts that were detrimental to the accurate detection of myocardial boundaries. This technique offers a fast and easy way to suppress off-resonance artifacts in SSFP imaging at 3 T.

Cyclic variation of T1 in the myocardium at 3 T

Standard methods of longitudinal relaxation (T1) measurements in the heart produce only one T1 map of the myocardium, usually at the end diastole (ED). In this article, we investigated the feasibility of using a dual flip angle fast gradient echo technique in the steady state to generate a movie of T1 maps in the myocardium during the cardiac cycle. The effects of nonideal slice profile and transient steady state on the T1 measurements were evaluated by Bloch simulations. Based on these results, we introduce a linear correction to the measured T1 values, which was validated by phantom experiments. In vivo T1 cine maps in healthy volunteers show 70+/-7% drop in T1 from the ED to the end systole in the septum and a 43+/-13% drop in the left ventricular lateral wall. With further improvements, this technique could be used to assess the myocardial blood volume changes during the cardiac cycle.

Assessment of mumps virus growth on various continuous cell lines by virological, immunological, molecular and morphological investigations

Vero cells have been used as a convenient laboratory substrate for the isolation of mumps virus but may not be very sensitive and may select for particular adapted variants from clinical specimens. Continuous cell lines were evaluated for their ability to support the replication of mumps virus. Criteria included the production of infectious virus, detection of intracellular mumps proteins by immunofluorescence and electron microscopy and detection of specific nucleic acid by RT-PCR. Of the cells tested, CaCo-2, PLC/PRF/5, and Vero cells produced infectious virus, with Vero and CaCo-2 being the most permissive. The other substrates tested included cells of murine, canine and human origin showed signs of intracellular proteins and RNA but the amounts produced were much lower, and no infectious virus was detected in some cases. The virus use was a low passage of a Vero derived wild type strain, and it will ultimately be necessary to continue the studies with an unpassaged clinical specimen to identify a cell line able to isolate mumps virus at high efficiency and in unmodified form.

Catalytic antibodies induced by a zwitterionic hapten

A zwitterionic hapten 4 featuring both positively and negatively charged functional groups was designed and synthesized with the goal of generating catalytic antibodies for the hydrolysis of ester 6 and amide 7. Of the 36 monoclonal antibodies specific to BSA-4 (bovine serum albumin) that were isolated, six accelerated the hydrolysis of 6. Two catalytic antibodies with distinctively different and representative kinetic behaviors were selected for detailed kinetic studies. Whereas H8-2-6F11 showed burst kinetic behavior, which can be attributed to the formation of an acyl intermediate, H8-1-2D5 did not, but it did exhibit high multiple turnover activity. The rate of hydrolysis of 6 catalyzed by H8-1-2D5 followed Michaelis-Menten kinetics; the apparent values of the Michaelis-Menten constant Km and the catalytic constant kcat were 488 microM and 3.5 min(-1), respectively. The catalytic rate enhancement (kcat/kun) observed for H8-1-2D5 was 1.3 x 10(5), which is approximately two orders of magnitude greater than those for monofunctional haptens. Thus H8-1-2D5 compares well in catalytic activity with antibodies isolated by a related approach called heterologous immunization.

Design and syntheses of three haptens to generate catalytic antibodies that cleave amide bonds with nucleophilic catalysis

Design principles and syntheses of three haptens that were recently reported to generate amide bond cleaving catalytic antibodies are described. The hapten designs sought to induce acidic and/or basic residues in antibody binding sites via charge complementarity, and also to generate a hydrophobic binding pocket for an external phenol nucleophile. The charged yet aromatic nature of these haptens presented some unique synthetic challenges and solutions to which are described below.

Two new stereotests for long distance: examination of stereopsis with regard to the permission of driving

Two differently constructed stereotests for a distance of 4 m are presented (tests A and B), which are based on the three-rod method of Helmholtz. In both tests, eight test objects are offered simultaneously, one of them being displaced toward the subject to a certain extent (100-10 s of arc). In test A the subject sees the eight test objects through eight holes, whereas in test B the test objects are seen directly. Each disparity is offered eight times. The threshold is defined as five of eight answers being correct. A total of 51 subjects without strabismus and with normal stereopsis in conventional tests achieved a mean stereo-acuity of 30 s of arc in test A and 10 s of arc in test B. The same subjects with one eye occluded and 49 patients with severe binocular defects reached chance scores only in test A, whereas in test B the success rate was improved slightly by monocular clues (P = 1/5). In examining stereopsis with regard to driving licenses, only tests for long distance should be used. Both new stereotests differentiate between normal and pathological candidates with high specificity and sensitivity.

Radiation protection against early and late effects of ionizing irradiation by the prostaglandin inhibitor indomethacin

Protective effects of indomethacin, a prototype prostaglandin-inhibiting agent, against early and late sequelae of radiation injury (after X-rays or gamma rays) in mice were investigated. The following tissues or organs were examined: hematopoietic tissue, esophagus, jejunum, colon, lung, hair follicles, and tissues involved in the development of radiation-induced leg contractures. In addition, the effect of indomethacin was tested against radiation-induced carcinogenesis. In all experiments, the radiation was delivered as a single dose. Indomethacin led to significant protection of hematopoietic tissue, by a factor of 1.3. There was also some protection against radiation-induced pneumonitis and against radiation-induced carcinogenesis (protection factor of 1.2). The other tissues tested showed no change in their radioresponse after being treated with indomethacin. Thus, indomethacin can act as a radioprotective agent against both early and late sequelae of radiation, but its effect is dependent on the tissue tested. This protection is smaller than that observed with WR-2721. However, indomethacin combined with WR-2721 produced a radioprotective effect greater than the radioprotection achieved by individual treatments.

Consequences of breast irradiation in patients with pre-existing collagen vascular diseases

Exaggerated acute and late effects were observed in three of four women with pre-existing collagen vascular disease (CVD) within 2 years after definitive megavoltage radiation therapy for breast carcinoma. Five women with breast carcinoma, who developed CVD 3 months to 10 years after radiation therapy, had no complications. An abnormally severe reaction was observed during treatment of one patient with discoid lupus. The patient developed moist desquamation that persisted for a month, requiring early termination of treatment. One year after treatment, the patient developed paresthesias in the ipsilateral arm. A planned reduction of the prescribed dose in a second patient with progressive systemic sclerosis did not prevent intense erythema at the end of treatment, followed 14 months later by chest wall necrosis, which eventually required multiple surgeries including chest wall resections. The third patient, who had systemic lupus erythematosis, developed necrosis 2 years after treatment, which progressed over 12 years to osteoradionecrosis of the clavicle, sternum and rib cage. Multiple surgeries to repair the defect were complicated by flap necrosis and pleurocutaneous fistulas. The fourth patient died 6 months after radiotherapy without apparent sequelae. None of the patients had evidence of recurrent carcinoma. A history of collagen vascular disease appears to be a contraindication to breast conservation or for elective irradiation for breast cancer.

Effect of isoprinosine on sialylation of interleukin-2

The effects of Isoprinosine (ISO) on interleukin-2 (IL-2) production by human peripheral blood mononuclear cells (PBMC) were investigated. Treatment (of human PBMC) with ISO enhanced IL-2 production by PBMC from 7 of 10 normal individuals. However, no augmentation of IL-2 production was observed when cultures of HUT-78 cells, a human leukemic T cell line, were treated with ISO. IL-2 purified from supernatants of human PBMC treated with ISO exhibited pI values of 5.5 and 6.4. IL-2 prepared from untreated PBMC exhibited a single pI value of 8.2. The pI value of IL-2 prepared from ISO-treated PBMC shifted to 8.2 after treatment with neuraminidase, demonstrating that the IL-2 molecules isolated from ISO-treated PBMC possessed sialic acid. The pI values of the IL-2 isolated from ISO-treated and untreated HUT-78 culture supernatants were identical (pI = 7.8) and were not modified by neuraminidase treatment. These results suggest that the increase in IL-2 production following treatment of PBMC with ISO may be mediated through the activation of a distinct subset of IL-2 producing cells. Furthermore, the sialylation of IL-2 may be of physiologic and immunopharmacologic importance.

Combined use of HFPPV with low-rate ventilation in traumatic respiratory insufficiency

Two patients with chest injuries, flail chest and respiratory failure were mechanically ventilated by a system composed of 2 Bennett respirators and an independent source of gas. This system provides high-frequency positive pressure ventilation (HFPPV), low-frequency conventional mechanical ventilation (LFCMV) and high inspiratory flow of fresh gas (HIF), through the independent source. This system made use of the advantages of HFPPV and also solved the problem of possible CO2 retention. Using this system we could ventilate the patients while they were fully conscious and cooperative, thus eliminating the need for sedatives and muscle relaxants. Time of mechanical ventilation was shortened since the internal pneumatic fixation was very good and made it possible for the fractured ribs to unite rapidly. Restoration of spontaneous breathing was immediate after disconnection from the ventilator. We suggest this method as another mode of ventilation for patients with flail chest and respiratory failure.