Experimental Investigation of a Digital Quadrupole Inductively Coupled Plasma Mass Spectrometer for Elemental Analysis.

We describe the development and initial characterization of a digital waveform scanning quadrupole mass filter (digital QMF) used for inductively coupled plasma mass spectrometry (ICP-MS). Unlike a conventional voltage scanning QMF, in the digital QMF, the frequency of the digital waveform is scanned to filter ions with different m/z through the quadrupole, and m/z is proportional to 1/f2. In digital QMF, the duty cycle of the digital waveform driving the quadrupole is modified such that stability regions of interest are accessible for mass analysis with no DC voltage applied. Here, we evaluate the performance of our digital ICP-QMS instrument at several duty cycles and corresponding stability zones: from zone 1 to zone 3,2. We demonstrate that, regardless of the stability zone used, frequency vs m/z calibration matches theory. For lower-order stability zones, the mass range of the analyzer is limited by the high-frequency waveform required; however, at zone 3,2, we demonstrate a mass range from at least 40 to 232 Th, which covers most of the elemental mass range. Similar to the conventional QMF, higher stability regions of the digital QMF can yield a higher resolution. We obtained the best resolution for our current instrument at zone 3,2 with a 62.50/37.50 duty cycle. The resolution at full-width at 10% peak height (R10%) was 1200 and 1100 for 115In+ and 232Th+, respectively. Lower pole bias yielded a R10% of 1400 for 40Ar+. Resolution and sensitivity comparisons indicate that higher q values and higher duty cycles lead to enhanced resolution, but lower sensitivity. Our results validate the operation of digital quadrupole ICP-MS and suggest that, with continuous improvement of electronics and instrumentation, a high resolution digital waveform scanning ICP-QMS for elemental analysis is possible.

Simulation study of digital waveform-driven quadrupole mass filter operated in higher stability regions for high-resolution inductively coupled plasma mass spectrometry.

RATIONALE: The use of a frequency-scanned digital quadrupole mass filter (QMF) with varying duty cycles shows promise for application as a high-resolution mass analyzer design for inductively coupled plasma mass spectrometry (ICP-MS). High resolution in ICP-MS is important to overcome isobaric polyatomic interferences. Here, we explore the possibility and the characteristics of using a digital quadrupole operating in higher stability regions for ICP-MS. METHODS: We perform computational simulations in SIMION of a digital QMF that is operated by scanning the frequency of the digital waveform at a fixed driving voltage and various duty cycles. For ions in the atomic mass range (7-238 m/z), we investigate the expected resolution, transmission, fringe field effects, and ion trajectories. We compare different characteristics between sine and digital waveform QMF. RESULTS: Within the capability of current digital waveform generation technology, a digital QMF can produce variable mass resolution, from several hundred to more than 10 000. This mass resolution covers the low, medium, and high resolutions that are typical for sector-field ICP-MS. Additionally, simulations suggest that transmission of the QMF remains high at high resolution. For example, with 87.50/12.50 duty cycle (zone 4,1), resolution at 10% peak width is 10 420 for m/z 80. The transmission through the quadrupole, which is constant for all isoenergetic ions, is ~2.5%, and most ion loss is due to the defocusing effects of the fringe field. Compared to sinusoidal QMFs, ions need many fewer cycles in the digital QMF to obtain high resolution. CONCLUSION: The results demonstrate that the use of a frequency-scanned, duty-cycle-modulated digital QMF as the mass analyzer for ICP-MS has the potential to produce high resolution while maintaining considerable transmission, thus overcoming most spectral interferences in elemental MS.

Comparative study of the vibrating capillary nebulizer (VCN) and commercially available interfaces for on-line coupling of capillary electrophoresis with ICP-MS.

Capillary electrophoresis (CE) is a powerful and sensitive tool for speciation analysis when combined with inductively coupled plasma mass spectrometry (ICP-MS); however, the performance of this technique can be limited by the nature of pneumatic nebulizers. This study compares two commercially available pneumatic nebulizers to a newly introduced vibrating capillary nebulizer (VCN) for on-line coupling of CE with ICP-MS. The VCN is a low-cost, non-pneumatic nebulizer that is based on the design of capillary vibrating sharp-edge spray ionization. As a piezoelectrically driven nebulization source, the VCN creates an aerosol independent of gas flows and does not produce a low-pressure region at the nebulizer orifice. To compare the systems, we performed replicate analyses of sulfate in river water with each nebulizer and the same CE and ICP-MS instruments and determined the figures of merit of each setup. With the CE-VCN-ICP-MS setup, we achieved around 2-4 times lower sensitivity compared to the commercial setups. However, the VCN-based setup provided lower noise levels and better linear correlation from the analysis of calibration standards, which resulted in indistinguishable LOD and LOQ values from the in-house-built VCN-based and commercial setups for CE-ICP-MS analysis. The VCN is found to have the highest baseline stability with a standard deviation of 3500 cts s-1, corresponding to an RSD of 2.7%. High reproducibility is found with the VCN with a peak area RSD of 4.1% between 3 replicate measurements.

Determination of carbon in microplastics and single cells by total consumption microdroplet ICP-TOFMS.

Recently, spICP-MS analyses of microplastics have demonstrated that the detection capabilities of ICP-MS are sufficient to determine the size and composition of such materials. However, solution nebulization or microdroplet generation limits the sizes of droplets, microparticles, or cells that can be efficiently introduced into commonly used horizontal ICP-MS configurations. Therefore, we introduced the development of a downward-pointing ICP coupled to a time-of-flight mass spectrometer (ICP-TOFMS), which enables quantitative transport of large microdroplets (diameters up to 90 µm) into the ICP. Here, we report the capabilities of downward ICP-TOFMS for the quantitative analysis of single cells and microplastic particles. For calibration of element mass amount per particle or cell, microdroplets (70 µm diameter) composed of multielement solutions were measured by ICP-TOFMS. Microplastic beads (polystyrene) and spleenocyte cells were then also embedded in microdroplets and measured by ICP-TOFMS with ion optics optimized to determine the signals from 12C+ and other isotopes of interest, including 140Ce, 153Eu, 165Ho, and 175Lu from the REE beads and 31P for the cells. The results achieved using the prototype instrument of a vertical downward-pointing ICP-TOFMS demonstrate that such a plasma configuration is well suited to analyze microplastics and single cells. For single microbead and cell analyses, the critical mass for carbon was 4.8 pg, and the mean determined carbon mass amounts were 14 and 23 pg, respectively. For the microbead analysis, the detected carbon mass corresponds to a particle diameter of 2.93 ± 0.24 µm, which is consistent with the scanning (transmission) electron microscopy-determined diameter of 2.97 ± 0.04 µm. Furthermore, in the analysis of spleenocyte cells, carbon and phosphorus masses were determined to be correlated.

Single-Particle ICP-TOFMS with Online Microdroplet Calibration: A Versatile Approach for Accurate Quantification of Nanoparticles, Submicron Particles, and Microplastics in Seawater.

Single particle inductively coupled plasma time-of-flight mass spectrometry (spICP-TOFMS) is a powerful analytical technique for quantifying elements in nanoparticles and microparticles; however, like most ICP-MS-based measurements, matrix effects can be a major challenge for accurate quantification in spICP-MS. Here, we report the use of online microdroplet calibration to overcome extreme matrix effects observed for the analysis of nanoparticles and microparticles in seawater. With online microdroplet calibration, particle-containing samples are introduced into the ICP along with monodisperse microdroplets containing known element mass amounts. The microdroplet standards, which experience the same plasma conditions as the analyte particles, are used to measure matrix-matched absolute element sensitivities. With online microdroplet calibration, one multielemental standard can be used to determine the element mass amounts in diverse types of analyte particles independent of the sample matrix. We evaluate the matrix tolerance of spICP-TOFMS with online microdroplet calibration through the analysis of metal nanoparticles, polystyrene microplastic beads doped with rare-earth elements, and metal-oxide submicrometer particles in artificial seawater. Our results demonstrate mass recoveries of 98-90% for the analysis of individual gold NPs in ultrapure water to 99% seawater. In the analysis of food-grade TiO2 submicron particles, accurate Ti-mass per particle is determined with matrix-caused signal attenuation up to 80% in a pure seawater matrix. We also demonstrate accurate diameter determinations of individual 3.4 µm polystyrene beads at concentrations of up to 80% simulated seawater. Furthermore, simultaneous and accurate quantification of rare-earth elements in the polystyrene beads is achieved.

Characterization and Quantification of Natural and Anthropogenic Titanium-Containing Particles Using Single-Particle ICP-TOFMS.

Titanium-containing nanoparticles (NPs) and submicrometer particles (µPs) in the environment can come from natural or anthropogenic sources. In this study, we investigate the use of single-particle inductively coupled plasma time-of-flight mass spectrometry (spICP-TOFMS) to measure and classify individual Ti-containing particles as either engineered (Ti-eng) or naturally occurring (Ti-nat) based on elemental composition and multielement mass ratios. We analyze mixtures of four Ti-containing particle types: anthropogenic food-grade TiO2 particles and particles from rutile, ilmenite, and biotite mineral samples. Through characterization of neat particle suspensions, we develop a decision-tree-based classification scheme to distinguish Ti-eng from Ti-nat particles and to classify individual Ti-nat particles by mineral type. Engineered TiO2 and rutile particles have the same major-element composition. To distinguish Ti-eng particles from rutile, we developed particle-type detection limits based on the average crustal abundance ratio of titanium to niobium. For our measurements, the average Ti mass needed to classify Ti-eng particles is 9.3 fg, which corresponds to a diameter of 211 nm for TiO2. From neat suspensions, we demonstrate classification rates of 55%, 32%, 75%, and 72% for Ti-eng, rutile, ilmenite, and biotite particles, respectively. Our classification approach minimizes false-positive classifications, with rates below 5% for all particle types. Individual Ti-eng particles can be accurately classified at the submicron size range, while the Ti-nat particles are classified in the nanoregime (diameter < 100 nm). Efficacy of our classification approach is demonstrated through the analysis of controlled mixtures of Ti-eng and Ti-nat and the analysis of natural streamwater spiked with Ti-eng particles. In control mixtures, Ti-eng particles can be measured and classified at particle-number concentrations (PNCs) 60-times lower than that of Ti-nat particles and across a PNC range of at least 3 orders of magnitude. In the streamwater sample, Ti-eng particles are classified at environmentally relevant PNCs that are 44-times lower than the background Ti-nat PNC and 2850-times lower than the total PNC.

Results of an interlaboratory comparison for characterization of Pt nanoparticles using single-particle ICP-TOFMS.

This study describes an interlaboratory comparison (ILC) among nine (9) laboratories to evaluate and validate the standard operation procedure (SOP) for single-particle (sp) ICP-TOFMS developed within the context of the Horizon 2020 project ACEnano. The ILC was based on the characterization of two different Pt nanoparticle (NP) suspensions in terms of particle mass, particle number concentration, and isotopic composition. The two Pt NP suspensions were measured using icpTOF instruments (TOFWERK AG, Switzerland). Two Pt NP samples were characterized and mass equivalent spherical sizes (MESSs) of 40.4 ± 7 nm and 58.8 ± 8 nm were obtained, respectively. MESSs showed <16% relative standard deviation (RSD) among all participating labs and <4% RSD after exclusion of the two outliers. A good agreement was achieved between the different participating laboratories regarding particle mass, but the particle number concentration results were more scattered, with <53% RSD among all laboratories, which is consistent with results from previous ILC studies conducted using ICP-MS instrumentation equipped with a sequential mass spectrometer. Additionally, the capabilities of sp-ICP-TOFMS to determine masses on a particle basis are discussed with respect to the potential for particle density determination. Finally, because quasi-simultaneous multi-isotope and multi-element determinations are a strength of ICP-TOFMS instrumentation, the precision and trueness of isotope ratio determinations were assessed. The average of 1000 measured particles yielded a precision of below ±1% for intensity ratios of the most abundant Pt isotopes, i.e.194Pt and 195Pt, while the accuracy of isotope ratios with the lower abundant isotopes was limited by counting statistics.

Mass-Dependent Critical Value Expressions for Particle Finding in Single-Particle ICP-TOFMS.

In time-of-flight mass spectrometry (TOFMS), ion detection is often achieved via electron multiplication followed by fast analog-to-digital conversion (ADC). This detection approach is chosen over time-to-digital conversion because it extends the dynamic range of TOFMS measurements, especially for transient analyses. However, fast ADC detection also introduces measurement noise fundamental to the electron multiplication process. In previous research, we demonstrated that TOFMS signals acquired with fast ADC follow a compound Poisson distribution in which the Poisson-distributed arrival of ions at the detector is compounded with the response profile of the electron multiplier. Here, we consider the influence of mass-to-charge (m/z)-dependent detector responses and their impact on particle-finding accuracy in single-particle inductively coupled plasma TOFMS (spICP-TOFMS). In spICP-TOFMS, highly time-resolved ion signals are recorded and particle signals are distinguished from background signals based on thresholding the data at m/z-specific critical values. Through Monte Carlo modeling with measured m/z-dependent detector responses, we generate compound Poisson model distributions and critical values that accurately account for the dispersion of measured signals. We test the accuracy of critical values through the analysis of dissolved element solutions and comparison of measured versus predicted event rates above critical value thresholds. The use of m/z-dependent compound Poisson critical values reduces false-positive particle identifications by one to two orders of magnitude compared to thresholding criteria based on normal or Poisson statistics. The improved accuracy and robustness of compound Poisson critical values enables automated multi-element particle finding in spICP-TOFMS.

Physicochemical Properties and Route of Systemic Delivery Control the In Vivo Dynamics and Breakdown of Radiolabeled Gold Nanostars.

The in vivo dynamics of nanoparticles requires a mechanistic understanding of multiple factors. Here, for the first time, the surprising breakdown of functionalized gold nanostars (F-AuNSs) conjugated with antibodies and 64 Cu radiolabels in vivo and in artificial lysosomal fluid ex vivo, is shown. The short-term biodistribution of F-AuNSs is driven by the route of systemic delivery (intravenous vs intraperitoneal) and long-term fate is controlled by the tissue type in vivo. In vitro studies including endocytosis pathways, intracellular trafficking, and opsonization, are combined with in vivo studies integrating a milieu of spectroscopy and microcopy techniques that show F-AuNSs dynamics is driven by their physicochemical properties and route of delivery. F-AuNSs break down into sub-20 nm broken nanoparticles as early as 7 days postinjection. Martini coarse-grained simulations are performed to support the in vivo findings. Simulations suggest that shape, size, and charge of the broken nanoparticles, and composition of the lipid membrane depicting various tissues govern the interaction of the nanoparticles with the membrane, and the rate of translocation across the membrane to ultimately enable tissue clearance. The fundamental study addresses critical gaps in the knowledge regarding the fate of nanoparticles in vivo that remain a bottleneck in their clinical translation.

Elemental Characterization of Leaded and Lead-Free Inorganic Primer Gunshot Residue Standards Using Single Particle Inductively Coupled Plasma Time-of-Flight Mass Spectrometry.

This study describes the use of single particle inductively coupled plasma time-of-flight mass spectrometry (spICP-TOFMS) for the detection and classification of inorganic gunshot residue (IGSR) particles. To establish reliable multi-element criteria to classify IGSR particles, leaded and lead-free IGSR reference materials were analyzed, and the elemental compositions of the individual particles were quantified. The results suggest that expanded element compositions may be used to classify IGSR particles via spICP-TOFMS compared to those used in conventional IGSR analysis using scanning electron microscopy energy dispersive X-ray spectroscopy (SEM-EDS). For spICP-TOFMS analysis of leaded IGSR particles, classification may be based on the presence of lead (Pb), antimony (Sb), and barium (Ba) just as in SEM-EDS; however, additional particle types, such as lead-copper (Pb-Cu) particles, contribute significantly (∼30%) to the leaded IGSR particle population. In lead-free IGSR particles, the dominate multi-metal particle composition found is titanium-zinc (Ti-Zn) with a conserved Zn:Ti ratio of 1.4:1, but other elements, such as copper (Cu), are also characteristic. In mixtures of the two IGSR reference materials, we were able to classify over 80% of the multi-metal particles detected with no false-positive particle-type assignments. With spICP-TOFMS, particles smaller than those typically measured by SEM-EDS are detected, with estimated median diameters for leaded and lead-free IGSR of 180 and 320 nm, respectively. Through measuring these smaller particles, up to ∼two times more particles per mL are recorded by spICP-TOFMS compared to that found by SEM-EDS. Overall, high-sensitivity and high-throughput analysis using spICP-TOFMS enables quantitative, rapid multi-elemental characterization, and classification of individual IGSR particles.

Detection of magnetic iron nanoparticles by single-particle ICP-TOFMS: case study for a magnetic filtration medical device.

Nanoparticles are increasingly used in medical products and devices. Their properties are critical for such applications, as particle characteristics determine their interaction with the biological system, and, therefore, the performance and safety of the final product. Among the most important nanoparticle characteristics and parameters are particle mass distribution, composition, total particle mass, and number concentration. In this study, we utilize single-particle inductively coupled plasma time-of-flight mass spectrometry (spICP-TOFMS) for the characterization of inorganic nanoparticles in complex biological fluids. We report online microdroplet calibration for reference-nanomaterial-free and matrix-matched calibration of carbon-coated iron carbide nanoparticles (C/Fe3C NPs). As a case study, we analyze C/Fe3C NPs designed for targeted blood purification. Through the analysis of NP mass distributions, we study the effect of the NP surface modification on aggregation of C/Fe3C NPs in whole blood. We also demonstrate the efficiency of removal of coated C/Fe3C NP from saline by magnetically enhanced filters. Magnetic filtering is shown to reduce the mass concentration of detectable C/Fe3C NPs by 99.99 ± 0.01% in water.

Online microdroplet calibration for accurate nanoparticle quantification in organic matrices.

Single-particle inductively coupled plasma time-of-flight mass spectrometry (spICP-TOFMS) is a high-throughput method for the multiplexed analysis of nanoparticles (NPs). However, matrix interferences are a significant challenge that must be overcome for accurate NP sizing and number concentration determination. In online microdroplet calibration, multi-element droplet standards are mixed with nebulized aerosols from a NP-containing sample in a dual-sample introduction system before entering the ICP. Microdroplet standards are used to determine absolute sensitivities and calibrate the mass amount(s) of analyte element(s) in particle events. A plasma-uptake standard is added to NP-containing samples to account for variations in the nebulization and transport efficiency of aerosols into the plasma, which are used in the determination of particle number concentrations (PNCs). Since the microdroplets experience the same plasma conditions as analyte NPs, this creates a matrix-matched calibration. We studied the efficacy of online microdroplet calibration for the quantification of NPs in three organic matrices: ethanol, acetone, and acetonitrile. Organic solvents can cause a pronounced increase in sample uptake and cause plasma-related signal attenuation for nanoparticle measurements. Online microdroplet calibration corrects for both effects without the use of nanoparticle standards. Our results demonstrate accurate NP sizing and PNC determinations in organic matrices up to 98% (v/v), even when these matrices caused signals to be attenuated up to 35-times and nebulizer transport efficiencies to be up to four-times higher than that of a pure water matrix.

Big data, computational social science, and other recent innovations in social network analysis.

While sociologists have studied social networks for about one hundred years, recent developments in data, technology, and methods of analysis provide opportunities for social network analysis (SNA) to play a prominent role in the new research world of big data and computational social science (CSS). In our review, we focus on four broad topics: (1) Collecting Social Network Data from the Web, (2) Non-traditional and Bipartite/Multi-mode Networks, including Discourse and Semantic Networks, and Social-Ecological Networks, (3) Recent Developments in Statistical Inference for Networks, and (4) Ethics in Computational Network Research.

Alors que les sociologues étudient les réseaux sociaux depuis une centaine d'années, les récents développements en matière de données, de technologie et de méthodes d'analyse offrent la possibilité à l'analyse des réseaux sociaux (ARS) de jouer un rôle de premier plan dans le nouveau monde de recherche du big data et des sciences sociales computationnelles (CSS). Dans notre revue, nous nous concentrons sur quatre grands sujets: (1) La collecte de données de réseaux sociaux sur le Web, (2) Les réseaux non traditionnels et bipartites/multimodes, y compris les réseaux discursifs et sémantiques, et les réseaux socio-écologiques, (3) Les développements récents de l'inférence statistique pour les réseaux, et (4) L'éthique dans la recherche informatique sur les réseaux.

Quantification and Clustering of Inorganic Nanoparticles in Wastewater Treatment Plants across Switzerland.

Single particle Inductively Coupled Plasma Time-of-Flight Mass Spectrometry (sp-ICP-TOFMS), in combination with online microdroplet calibration, allows the determination of particle number concentrations (PNCs) and the masses of elements in individual particles. Because sp-ICP-TOFMS analyses of environmental samples produce rich datasets composed of both single-metal nanoparticles (smNPs) and many types of multimetal NPs (mmNPs), interpretation of these data is well suited to automated analysis schemes. Here, we present a data analysis approach that includes automatic particle detection and elemental mass determinations based on online microdroplet calibration, and unsupervised clustering analysis of mmNPs to identify unique classes of NPs based on their element compositions. To demonstrate the potential of our approach, we analyzed wastewater samples collected from the influent and effluent of five wastewater treatment plants (WWTPs) across Switzerland. We determined elemental masses in individual NPs, as well as PNCs, to estimate the NP removal efficiencies of the individual WWTPs. Through hierarchical clustering, we identified NP classes conserved across all WWTPs; the most abundant particle types were those rich in Ce-La, Fe-Al, Ti-Zr, and Zn-Cu. In addition, we found particle types that are unique to one or a few WWTPs, which could indicate point sources of anthropogenic NPs.

Emerging investigator series: automated single-nanoparticle quantification and classification: a holistic study of particles into and out of wastewater treatment plants in Switzerland.

Single particle inductively coupled plasma time-of-flight mass spectrometry (sp-ICP-TOFMS), in combination with online microdroplet calibration, allows for the determination of particle number concentrations (PNCs) and the amount (i.e. mass) of ICP-MS-accessible elements in individual particles. Because sp-ICP-TOFMS analyses of environmental samples produce rich datasets composed of both single-metal nanoparticles (smNPs) and many types of multi-metal NPs (mmNPs), interpretation of these data is well suited to automated analysis schemes. Here, we present a new data analysis approach that includes: 1. automatic particle detection and elemental mass determinations based on online microdroplet calibration, 2. correction of false (randomly occurring) multi-metal associations caused by measurement of coincident but distinct NPs, and 3. unsupervised clustering analysis of mmNPs to identify unique classes of NPs based on their element compositions. To demonstrate the potential of our approach, we analyzed water samples collected from the influent and effluent of five wastewater treatment plants (WWTPs) across Switzerland. We determined elemental masses in individual NPs, as well as PNCs, to estimate the NP removal efficiencies of the individual WWTPs. From WWTP samples collected at two points in time, we found an average of 90% and 94% removal efficiencies of single-metal and multi-metal NPs, respectively. Between 5% to 27% of detected NPs were multi-metal; the most abundant particle types were those rich in Ce-La, Fe-Al, Ti-Zr, and Zn-Cu. Through hierarchical clustering, we identified NP classes conserved across all WWTPs, as well as particle types that are unique to one or a few WWTPs. These uniquely occurring particle types may represent point sources of anthropogenic NPs. We describe the utility of clustering analysis of mmNPs for identifying natural, geogenic NPs, and also for the discovery of new, potentially anthropogenic, NP targets.

Reverse Trigger Phenotypes in Acute Respiratory Distress Syndrome.

Rationale: Reverse triggering is an underexplored form of dyssynchrony with important clinical implications in patients with acute respiratory distress syndrome.Objectives: This retrospective study identified reverse trigger phenotypes and characterized their impacts on Vt and transpulmonary pressure.Methods: Fifty-five patients with acute respiratory distress syndrome on pressure-regulated ventilator modes were included. Four phenotypes of reverse triggering with and without breath stacking and their impact on lung inflation and deflation were investigated.Measurements and Main Results: Inflation volumes, respiratory muscle pressure generation, and transpulmonary pressures were determined and phenotypes differentiated using Campbell diagrams of respiratory activity. Reverse triggering was detected in 25 patients, 15 with associated breath stacking, and 13 with stable reverse triggering consistent with respiratory entrainment. Phenotypes were associated with variable levels of inspiratory effort (mean 4-10 cm H2O per phenotype). Early reverse triggering with early expiratory relaxation increased Vts (88 [64-113] ml) and inspiratory transpulmonary pressures (3 [2-3] cm H2O) compared with passive breaths. Early reverse triggering with delayed expiratory relaxation increased Vts (128 [86-170] ml) and increased inspiratory and mean-expiratory transpulmonary pressure (7 [5-9] cm H2O and 5 [4-6] cm H2O). Mid-cycle reverse triggering (initiation during inflation and maximal effort during deflation) increased Vt (51 [38-64] ml), increased inspiratory and mean-expiratory transpulmonary pressure (3 [2-4] cm H2O and 3 [2-3] cm H2O), and caused incomplete exhalation. Late reverse triggering (occurring exclusively during exhalation) increased mean expiratory transpulmonary pressure (2 [1-2] cm H2O) and caused incomplete exhalation. Breath stacking resulted in large delivered volumes (176 [155-197] ml).Conclusions: Reverse triggering causes variable physiological effects, depending on the phenotype. Differentiation of phenotype effects may be important to understand the clinical impacts of these events.

Oncolytic herpesvirus therapy for mesothelioma - A phase I/IIa trial of intrapleural administration of HSV1716.

OBJECTIVES: Malignant Pleural Mesothelioma (MPM) remains a major oncological challenge with limited therapeutic options. HSV1716 is a replication restricted oncolytic herpes simplex virus with anti-tumor effects in multiple cell lines including MPM. Intrapleural treatment appeals because MPM is typically multifocal but confined to the pleura, and distant metastases are uncommon. We assessed the safety and possible efficacy of intrapleural HSV1716 for inoperable MPM. MATERIALS AND METHODS: Patients with MPM received 1 × 107iu HSV1716 injected via an indwelling intrapleural catheter (IPC) on one, two or four occasions a week apart. The primary endpoint was the safety and tolerability of HSV1716. Secondary endpoints were assessment of HSV1716 replication, detection of immune response and evaluation of tumor response. RESULTS: Of thirteen patients enrolled, five had received previous pemetrexed-cisplatin chemotherapy, and eight were chemotherapy naïve. Three patients were enrolled to receive one dose, three patients to two doses and seven patients to four doses. The treatment was well-tolerated with few virus-related adverse events and no dose limiting toxicities. Twelve patients were evaluable for response, as one patient withdrew early after a catheter fracture. There was evidence of viral replication/persistence in pleural fluid in seven of the twelve patients. Induction of Th1 cytokine responses to HSV1716 treatment occurred in eight patients and four patients developed novel anti-tumor IgG. No objective responses were observed but disease stabilization was reported in 50 % of patients at 8 weeks. CONCLUSIONS: Intrapleural HSV1716 was well-tolerated and demonstrated an anti-tumor immune response in MPM patients. These results provide a rationale for further studies with this agent in MPM and in combination with other therapies.

Clinical Safety and Cost-Effectiveness of Follow-up Virtual Clinic for Bladder Outflow Obstruction Surgery.

Introduction: Bladder outflow obstruction (BOO) surgery is among the most commonly performed urologic procedures. Postoperative assessment consists of physical measurement of uroflowmetry and post-void residual volume, but health systems worldwide have experienced pressures in demand, leading to exploration of greater efficiency in organizing clinic protocols. International Prostate Symptom Score (IPSS) questionnaire measurement has been identified as a tool to predict change in postoperative management. Our institution established a nurse-led follow-up virtual clinic (VC) for patients undergoing BOO surgery based on IPSS measurement. We present the clinical and economic outcomes of this new service. Materials and Methods: Patients with a successful postoperative trial without catheter were contacted by telephone via VC and discharged by a Urology Clinical Nurse Specialist (UCNS) if IPSS was <8. Data were analyzed for IPSS, arrangement of subsequent clinic visits, and numbers discharged. Primary outcome was the proportion of patients discharged after VC consultation. Secondary outcomes were overall discharge rate following subsequent face-to-face (FTF) appointment; and the proportion of patients re-referred from Primary Care within 3 months of discharge from VC. Cost savings were calculated based on tariffs of £135 for first attendance with UCNS, £199 for uroflowmetry, and £47.84 for VC appointment. Results: The first 50 patients to be recipients of the new VC were included. The median IPSS and quality-of-life score were 13 (interquartile range [IQR] 5) and 3 (IQR 1), respectively. Thirty-nine (78%) patients were discharged from VC; 36 (72%) had IPSS <8. Overall discharge rate following subsequent FTF appointment was 88%. Two patients discharged from VC (5.1%) were subsequently re-referred, neither of whom required additional treatment. Total cost savings with VC amounted to £10,634. Conclusion: Telephone follow-up for BOO surgery based on IPSS is clinically safe and cost-effective, providing greater efficiency for clinic protocols.

The development of a high throughput drug-responsive model of white adipose tissue comprising adipogenic 3T3-L1 cells in a 3D matrix.

Adipose models have been applied to mechanistic studies of metabolic diseases (such as diabetes) and the subsequent discovery of new therapeutics. However, typical models are either insufficiently complex (2D cell cultures) or expensive and labor intensive (mice/in vivo). To bridge the gap between these models and in order to better inform pre-clinical studies we have developed a drug-responsive 3D model of white adipose tissue (WAT). Here, spheroids (680 ± 60 µm) comprising adipogenic 3T3-L1 cells encapsulated in 3D matrix were fabricated manually on a 96 well scale. Spheroids were highly characterised for lipid morphology, selected metabolite and adipokine secretion, and gene expression; displaying significant upregulation of certain adipogenic-specific genes compared with a 2D model. Furthermore, induction of lipolysis and promotion of lipogenesis in spheroids could be triggered by exposure to 8-br-cAMP and oleic-acid respectively. Metabolic and high content imaging data of spheroids exposed to an adipose-targeting drug, rosiglitazone, resulted in dose-responsive behavior. Thus, our 3D WAT model has potential as a powerful scalable tool for compound screening and for investigating adipose biology.

Replacing the Argon ICP: Nitrogen Microwave Inductively Coupled Atmospheric-Pressure Plasma (MICAP) for Mass Spectrometry.

We combine a recently developed high-power, nitrogen-sustained microwave plasma source-the Microwave Inductively Coupled Atmospheric-Pressure Plasma (MICAP)-with time-of-flight mass spectrometry (TOFMS) and provide the first characterization of this elemental mass spectrometry configuration. Motivations for assessment of this ionization source are scientific and budgetary: unlike the argon-sustained Inductively Coupled Plasma (ICP), the MICAP is sustained with nitrogen, which eliminates high operating costs associated with argon-gas consumption. Additionally, use of a commercial grade magnetron for microwave generation simplifies plasma-powering electronics. In this study, we directly compare MICAP-TOFMS performance with that of an argon-ICP as the atomic ionization source on the same TOFMS instrument. Initial results with the MICAP source demonstrate limits of detection and sensitivities that are, for most elements, on par with those of the ICP-TOFMS. The N2-MICAP source provides a much "cleaner" background spectrum than the ICP; absence of argon-based interferences greatly simplifies analysis of isotopes such as 40Ca, 56Fe, and 75As, which typically suffer from spectral interferences in ICP-MS. The major plasma species measured from the N2-MICAP source include NO+, N2+, N+, N3+, O2+, N4+, and H2O+; we observed no plasma-background species above mass-to-charge 60. Absence of troublesome argon-based spectral interferences is a compelling advantage of the MICAP source. For example, with MICAP-TOFMS, the limit of detection for arsenic is less than 100 ng L-1 even in a 1% NaCl solution; with ICP-MS, 35Cl40Ar+ interferes with 75As+ and arsenic analysis is difficult-to-impossible in chlorine-containing matrices.