Whole genome sequencing of a family with autosomal dominant features within the oculoauriculovertebral spectrum

Background

Oculoauriculovertebral Spectrum (OAVS) encompasses a wide variety of anomalies on derivatives from the first and second pharyngeal arches including macrostomia, hemifacial microsomia, micrognathia, preauricular tags, ocular and vertebral anomalies. We present the genetic findings of a large three-generation family with multiple members affected with macrostomia, preauricular tags and uni- or bilateral ptosis following an autosomal dominant segregation pattern.

Methods

We generated whole genome sequencing data for the proband, affected parent and unaffected paternal grandparent followed by Sanger sequencing on 23 family members for the top 10 candidate genes: KCND2, PDGFRA, CASP9, NCOA3, WNT10A, SIX1, MTF1, KDR/VEGFR2, LRRK1, and TRIM2. We performed parent and sibling-based transmission disequilibrium tests and burden analysis to explore segregation and burden of candidate gene mutations. Bioinformatic analyses investigated the biological connection between genes and the abnormal phenotypes.

Results

Overall, rare missense mutations in SIX1, KDR/VEGFR2, and PDGFRA showed the best evidence of segregation with the OAV phenotypes in this family. When considering affection with any of the 3 OAVS phenotypes as an outcome, parent-TDTs and sib-TDTs (unadjusted p-values) found that SIX1 (p=0.025, p=0.052), followed by PDGFRA (p=0.180, p=0.069) and KDR/VEGFR2 (p=0.180, p=0.069) have the strongest associations in this family. Burden analysis via a penalized linear mixed model identified SIX1 (RC=0.87) and PDGFRA (RC=0.98) as having the strongest association with OAVS severity. Using phenotype-specific ogfrautcomes, sib-TDTs identified associations between (1) SIX1 with uni- or bilateral ptosis (p=0.049) and ear tags (p=0.01), (2) PDGFRA and KDR/VEGFR2 with ear tags (both p<0.01).

Conclusion

Our study reports the genomic findings of a large family with multiple individuals affected with OAVS phenotypes with autosomal dominant inheritance. Our findings narrow down to three potential candidate genes, SIX1, PDGFRA, and KDR/VEGFR2. Among these, SIX1 has been previously associated with OAVS ear malformations and it is co-expressed with EYA1 during ear development. Attempts to strengthen the genotype-phenotype co-relation underlying the OAVS of phenotypes are essential to discover the etiological factors leading to this complex and burdensome condition as well as for family counseling and prevention efforts.

Exposure assessment during paint spraying and drying using PTR-ToF-MS

Spraying is a common way to distribute occupational products, but it puts worker's health at risk by exposing them to potentially harmful particles and gases. The objective of this study is to use time-resolved measurements to gain an understanding of spray applications at the process level and to compare them to predictions of exposure models. We used proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) at 1-s time resolution to monitor the gas phase concentration of the solvents acetone, ethanol, butyl acetate, xylene and 1-methoxy-2-propy acetate during outdoor spraying and indoor drying of metal plate under various conditions of outdoor air supply. We found that during spraying, gas-phase exposure was dominated by the more volatile solvents acetone and ethanol, which exhibited strong concentration variations due to the outdoor winds. During drying, exposure strongly depended on the strength of ventilation. Under conditions with high supply of outdoor air, our measurements show a near-exponential decay of the solvent concentrations during drying. Conversely, under conditions without outdoor air supply, the drying process required hours, during which the less volatile solvents passed through a concentration maximum in the gas phase, so that the exposure during drying exceeded the exposure during spraying. The concentrations measured during spraying were then compared for each of the substances individually with the predictions of the exposure models ECETOC TRA, Stoffenmanager, and ART using TREXMO. For these conditions, ECETOC TRA and Stoffenmanager predicted exposures in the measured concentration range, albeit not conservative for all solvents and each application. In contrast, ART largely overestimated the exposure for the more volatile solvents acetone and ethanol and slightly underestimated exposure to 1M2PA for one spraying. ECETOC TRA and ART do not have options to predict exposure during drying. Stoffenmanager has the option to predict drying together with spraying, but not to predict the drying phase independently. Our study demonstrates the importance of considering both the spray cloud and solvent evaporation during the drying process. To improve workplace safety, there is a critical need for enhanced exposure models and comprehensive datasets for calibration and validation covering a broader range of exposure situations.

The neuraminidase activity of influenza A virus determines the strain-specific sensitivity to neutralization by respiratory mucus

IMPORTANCE

The respiratory tract of humans is constantly exposed to potentially harmful agents, such as small particles or pathogens, and thus requires protective measures. Respiratory mucus that lines the airway epithelia plays a major role in the prevention of viral infections by limiting the mobility of viruses, allowing subsequent mucociliary clearance. Understanding the interplay between respiratory mucus and viruses can help elucidate host and virus characteristics that enable the initiation of infection. Here, we tested a panel of primary influenza A viruses of avian or human origin for their sensitivity to mucus derived from primary human airway cultures and found that differences between virus strains can be mapped to viral neuraminidase activity. We also show that binding of influenza A viruses to decoy receptors on highly glycosylated mucus components constitutes the major inhibitory function of mucus against influenza A viruses.

Inactivation mechanisms of influenza A virus under pH conditions encountered in aerosol particles as revealed by whole-virus HDX-MS

Multiple respiratory viruses, including influenza A virus (IAV), can be transmitted via expiratory aerosol particles, and aerosol pH was recently identified as a major factor influencing airborne virus infectivity. Indoors, small exhaled aerosols undergo rapid acidification to pH ~4. IAV is known to be sensitive to mildly acidic conditions encountered within host endosomes; however, it is unknown whether the same mechanisms could mediate viral inactivation within the more acidic aerosol micro-environment. Here, we identified that transient exposure to pH 4 caused IAV inactivation by a two-stage process, with an initial sharp decline in infectious titers mainly attributed to premature attainment of the post-fusion conformation of viral protein haemagglutinin (HA). Protein changes were observed by hydrogen-deuterium exchange coupled to mass spectrometry (HDX-MS) as early as 10 s post-exposure to acidic conditions. Our HDX-MS data are in agreement with other more labor-intensive structural analysis techniques, such as X-ray crystallography, highlighting the ease and usefulness of whole-virus HDX-MS for multiplexed protein analyses, even within enveloped viruses such as IAV. Additionally, virion integrity was partially but irreversibly affected by acidic conditions, with a progressive unfolding of the internal matrix protein 1 (M1) that aligned with a more gradual decline in viral infectivity with time. In contrast, no acid-mediated changes to the genome or lipid envelope were detected. Improved understanding of respiratory virus fate within exhaled aerosols constitutes a global public health priority, and information gained here could aid the development of novel strategies to control the airborne persistence of seasonal and/or pandemic influenza in the future. IMPORTANCE It is well established that COVID-19, influenza, and many other respiratory diseases can be transmitted by the inhalation of aerosolized viruses. Many studies have shown that the survival time of these airborne viruses is limited, but it remains an open question as to what drives their infectivity loss. Here, we address this question for influenza A virus by investigating structural protein changes incurred by the virus under conditions relevant to respiratory aerosol particles. From prior work, we know that expelled aerosols can become highly acidic due to equilibration with indoor room air, and our results indicate that two viral proteins are affected by these acidic conditions at multiple sites, leading to virus inactivation. Our findings suggest that the development of air treatments to quicken the speed of aerosol acidification would be a major strategy to control infectious bioburdens in the air.

Comparison of ozonesonde measurements in the upper troposphere and lower Stratosphere in Northern India with reanalysis and chemistry-climate-model data

The variability and trend of ozone (O₃) in the Upper troposphere and Lower Stratosphere (UTLS) over the Asian region needs to be accurately quantified. Ozone in the UTLS radiatively heats this region and cools the upper parts of the stratosphere. This results in an impact on relative humidity, static stability in the UTLS region and tropical tropopause temperature. A major challenge for understanding ozone chemistry in the UTLS is sparse observations and thus the representation of precursor gases in model emission inventories. Here, we evaluate ozonesonde measurements during August 2016 at Nainital, in the Himalayas, against ozone from multiple reanalyses and the ECHAM6-HAMMOZ model. We find that compared to measurements both reanalyses and ECHAM6-HAMMOZ control simulation overestimate ozone mixing ratios in the troposphere (20 ppb) and in the UTLS (55 ppb). We performed sensitivity simulations using the ECHAM6-HAMMOZ model for a 50% reduction in the emission of (1) NOx and (2) VOCs. The model simulations with NO_X reduction agree better with the ozonesonde observations in the lower troposphere and in the UTLS. Thus, neither reanalyses nor ECHAM6-HAMMOZ results can reproduce observed O₃ over the South Asian region. For a better representation of O₃ in the ECHAM6-HAMMOZ model, NO_X emission should be reduced by 50% in the emission inventory. A larger number of observations of ozone and precursor gases over the South Asian region would improve the assessment of ozone chemistry in models.

Surface tension models for binary aqueous solutions: a review and intercomparison

The liquid-air surface tension of aqueous solutions is a fundamental quantity in multi-phase thermodynamics and fluid dynamics and thus relevant in many scientific and engineering fields. Various models have been proposed for its quantitative description. This Perspective gives an overview of the most popular models and their ability to reproduce experimental data of ten binary aqueous solutions of electrolytes and organic molecules chosen to be representative of different solute types. In addition, we propose a new model which reproduces sigmoidal curve shapes (Sigmoid model) to empirically fit experimental surface tension data. The surface tension of weakly surface-active substances is well reproduced by all models. In contrast, only few models successfully model the surface tension of aqueous solutions with strongly surface-active substances. For substances with a solubility limit, usually no experimental data is available for the surface tension of supersaturated solutions and the pure liquid solute. We discuss ways in which these can be estimated and emphasize the need for further research. The newly developed Sigmoid model best reproduces the surface tension of all tested solutions and can be recommended as a model for a broad range of binary mixtures and over the entire concentration range.

Expiratory Aerosol pH: The Overlooked Driver of Airborne Virus Inactivation

Respiratory viruses, including influenza virus and SARS-CoV-2, are transmitted by the airborne route. Air filtration and ventilation mechanically reduce the concentration of airborne viruses and are necessary tools for disease mitigation. However, they ignore the potential impact of the chemical environment surrounding aerosolized viruses, which determines the aerosol pH. Atmospheric aerosol gravitates toward acidic pH, and enveloped viruses are prone to inactivation at strong acidity levels. Yet, the acidity of expiratory aerosol particles and its effect on airborne virus persistence have not been examined. Here, we combine pH-dependent inactivation rates of influenza A virus (IAV) and SARS-CoV-2 with microphysical properties of respiratory fluids using a biophysical aerosol model. We find that particles exhaled into indoor air (with relative humidity ≥ 50%) become mildly acidic (pH ∼ 4), rapidly inactivating IAV within minutes, whereas SARS-CoV-2 requires days. If indoor air is enriched with nonhazardous levels of nitric acid, aerosol pH drops by up to 2 units, decreasing 99%-inactivation times for both viruses in small aerosol particles to below 30 s. Conversely, unintentional removal of volatile acids from indoor air may elevate pH and prolong airborne virus persistence. The overlooked role of aerosol acidity has profound implications for virus transmission and mitigation strategies.

European aerosol phenomenology - 8: Harmonised source apportionment of organic aerosol using 22 Year-long ACSM/AMS datasets

Organic aerosol (OA) is a key component of total submicron particulate matter (PM1), and comprehensive knowledge of OA sources across Europe is crucial to mitigate PM1 levels. Europe has a well-established air quality research infrastructure from which yearlong datasets using 21 aerosol chemical speciation monitors (ACSMs) and 1 aerosol mass spectrometer (AMS) were gathered during 2013-2019. It includes 9 non-urban and 13 urban sites. This study developed a state-of-the-art source apportionment protocol to analyse long-term OA mass spectrum data by applying the most advanced source apportionment strategies (i.e., rolling PMF, ME-2, and bootstrap). This harmonised protocol was followed strictly for all 22 datasets, making the source apportionment results more comparable. In addition, it enables quantification of the most common OA components such as hydrocarbon-like OA (HOA), biomass burning OA (BBOA), cooking-like OA (COA), more oxidised-oxygenated OA (MO-OOA), and less oxidised-oxygenated OA (LO-OOA). Other components such as coal combustion OA (CCOA), solid fuel OA (SFOA: mainly mixture of coal and peat combustion), cigarette smoke OA (CSOA), sea salt (mostly inorganic but part of the OA mass spectrum), coffee OA, and ship industry OA could also be separated at a few specific sites. Oxygenated OA (OOA) components make up most of the submicron OA mass (average = 71.1%, range from 43.7 to 100%). Solid fuel combustion-related OA components (i.e., BBOA, CCOA, and SFOA) are still considerable with in total 16.0% yearly contribution to the OA, yet mainly during winter months (21.4%). Overall, this comprehensive protocol works effectively across all sites governed by different sources and generates robust and consistent source apportionment results. Our work presents a comprehensive overview of OA sources in Europe with a unique combination of high time resolution (30-240 min) and long-term data coverage (9-36 months), providing essential information to improve/validate air quality, health impact, and climate models.

Electrodynamic balance–mass spectrometry reveals impact of oxidant concentration on product composition in the ozonolysis of oleic acid

Electrodynamic balance–mass spectrometry measurements reveal how the ozone concentration influences the product composition of oleic acid aerosol droplets.

Response to Comment on "A global environmental crisis 42,000 years ago"

[Figure: see text].

Response to Comment on "A global environmental crisis 42,000 years ago"

Our paper about the impacts of the Laschamps Geomagnetic Excursion 42,000 years ago has provoked considerable scientific and public interest, particularly in the so-called Adams Event associated with the initial transition of the magnetic poles. Although we welcome the opportunity to discuss our new ideas, Hawks' assertions of misrepresentation are especially disappointing given his limited examination of the material.

A global environmental crisis 42,000 years ago

Geological archives record multiple reversals of Earth's magnetic poles, but the global impacts of these events, if any, remain unclear. Uncertain radiocarbon calibration has limited investigation of the potential effects of the last major magnetic inversion, known as the Laschamps Excursion [41 to 42 thousand years ago (ka)]. We use ancient New Zealand kauri trees (Agathis australis) to develop a detailed record of atmospheric radiocarbon levels across the Laschamps Excursion. We precisely characterize the geomagnetic reversal and perform global chemistry-climate modeling and detailed radiocarbon dating of paleoenvironmental records to investigate impacts. We find that geomagnetic field minima ~42 ka, in combination with Grand Solar Minima, caused substantial changes in atmospheric ozone concentration and circulation, driving synchronous global climate shifts that caused major environmental changes, extinction events, and transformations in the archaeological record.

Constraining Atmospheric Selenium Emissions Using Observations, Global Modeling, and Bayesian Inference

Selenium (Se) is an essential dietary element for humans and animals, and the atmosphere is an important source of Se to soils. However, estimates of global atmospheric Se fluxes are highly uncertain. To constrain these uncertainties, we use a global model of atmospheric Se cycling and a database of more than 600 sites where Se in aerosol has been measured. Applying Bayesian inference techniques, we determine the probability distributions of global Se emissions from the four major sources: anthropogenic activities, volcanoes, marine biosphere, and terrestrial biosphere. Between 29 and 36 Gg of Se are emitted to the atmosphere every year, doubling previous estimates of emissions. Using emission parameters optimized by aerosol network measurements, our model shows good agreement with the aerosol Se observations (R² = 0.66), as well as with independent aerosol (0.59) and wet deposition measurements (0.57). Both model and measurements show a decline in Se over North America in the last two decades because of changes in technology and energy policy. Our results highlight the role of the ocean as a net atmospheric Se sink, with around 7 Gg yr^-1 of Se transferred from land through the atmosphere. The constrained Se emissions represent a substantial step forward in understanding the global Se cycle.

Numerical simulations of self-diffusiophoretic colloids at fluid interfaces

The dynamics of active colloids is very sensitive to the presence of boundaries and interfaces which therefore can be used to control their motion. Here we analyze the dynamics of active colloids adsorbed at a fluid-fluid interface. By using a mesoscopic numerical approach which relies on an approximated numerical solution of the Navier-Stokes equation, we show that when adsorbed at a fluid interface, an active colloid experiences a net torque even in the absence of a viscosity contrast between the two adjacent fluids. In particular, we study the dependence of this torque on the contact angle of the colloid with the fluid-fluid interface and on its surface properties. We rationalize our results via an approximate approach which accounts for the appearance of a local friction coefficient. By providing insight into the dynamics of active colloids adsorbed at fluid interfaces, our results are relevant for two-dimensional self assembly and emulsion stabilization by means of active colloids.

Carbon Dioxide Diffusivity in Single, Levitated Organic Aerosol Particles

The diffusivity of molecules relevant to condensed-phase chemistry within viscous secondary organic aerosol (SOA) remains highly uncertain. Whereas there has been an effort to characterize water diffusivity as well as the diffusivity of larger compounds, data are lacking almost entirely for small molecules, such as carbon dioxide (CO₂). Here we use photochemically generated CO₂ in single particles of aqueous citric acid as a SOA proxy, levitated in an electrodynamic balance, to deduce CO₂ diffusivity in the particle with unprecedented accuracy. For medium viscosities at intermediate relative humidities (∼25-40% RH), we find CO₂ diffusivities D_CO2 ≈ 10^-14 m² s^-1, agreeing with the Stokes-Einstein relationship based on current viscosity data but 10 times lower than that for water. Conversely, under dry high-viscosity conditions, we find that D_CO2 ≈ 10^-16 m² s^-1, which is 10 times higher than for water. We infer that the chemical degradation of atmospheric SOA particles will likely not be limited by CO₂ diffusivity.

Retrieval of Aerosol Size Distributions From In Situ Particle Counter Measurements: Instrument Counting Efficiency and Comparisons With Satellite Measurements

The method to derive aerosol size distributions from in situ stratospheric measurements from the University of Wyoming is modified to include an explicit counting efficiency function (CEF) to describe the channel-dependent instrument counting efficiency. This is motivated by Kovilakam and Deshler's (2015, https://doi.org/10.1002/2015JD023303) discovery of an error in the calibration method applied to the optical particle counter (OPC40) developed in the late 1980s and used from 1991 to 2012. The method can be applied to other optical aerosol instruments for which counting efficiencies have been measured. The CEF employed is the integral of the Gaussian distribution representing the instrument response at any one aerosol channel, the aerosol counting efficiency. Results using the CEF are compared to previous derivations of aerosol size distributions (Deshler et al., 2003, https://doi.org/10.1029/2002JD002514) applied to the measurements before and after Kovilakam and Deshler's correction of number concentration for the OPC40 calibration error. The CEF method is found, without any tuning parameter, to reproduce or improve upon the Kovilakam and Deshler's results, thus accounting for the calibration error without any external comparisons other than the laboratory determined counting efficiency at each aerosol channel. Moments of the new aerosol size distributions compare well with aerosol extinctions measured by Stratospheric Aerosol and Gas Experiment II and Halogen Occultation Experiment in the volcanic period 1991-1996, generally within ±40%, the precision of OPC40 moments, and in the nonvolcanic period after 1996, generally within ±20%. Stratospheric Aerosol and Gas Experiment II and Halogen Occultation Experiment estimates of aerosol surface area are generally in agreement with those derived using the new CEF method.

A Versatile Protein and Cell Patterning Method Suitable for Long-Term Neural Cultures

Herein, we present an easy-to-use protein and cell patterning method relying solely on pipetting, rinsing steps and illumination with a desktop lamp, which does not require any expensive laboratory equipment, custom-built hardware or delicate chemistry. This method is based on the adhesion promoter poly(allylamine)-grafted perfluorophenyl azide, which allows UV-induced cross-linking with proteins and the antifouling molecule poly(vinylpyrrolidone). Versatility is demonstrated by creating patterns with two different proteins and a polysaccharide directly on plastic well plates and on glass slides, and by subsequently seeding primary neurons and C2C12 myoblasts on the patterns to form islands and mini-networks. Patterning characterization is done via immunohistochemistry, Congo red staining, ellipsometry, and infrared spectroscopy. Using a pragmatic setup, patterning contrasts down to 5 μm and statistically significant long-term stability superior to the gold standard poly(l-lysine)-grafted poly(ethylene glycol) could be obtained. This simple method can be used in any laboratory or even in classrooms and its outstanding stability is especially interesting for long-term cell experiments, e.g., for bottom-up neuroscience, where well-defined microislands and microcircuits of primary neurons are studied over weeks.

Tropospheric ozone in CCMI models and Gaussian process emulation to understand biases in the SOCOLv3 chemistry-climate model

Previous multi-model intercomparisons have shown that chemistry-climate models exhibit significant biases in tropospheric ozone compared with observations. We investigate annual-mean tropospheric column ozone in 15 models participating in the SPARC/IGAC (Stratosphere-troposphere Processes and their Role in Climate/International Global Atmospheric Chemistry) Chemistry-Climate Model Initiative (CCMI). These models exhibit a positive bias, on average, of up to 40-50% in the Northern Hemisphere compared with observations derived from the Ozone Monitoring Instrument and Microwave Limb Sounder (OMI/MLS), and a negative bias of up to ~30% in the Southern Hemisphere. SOCOLv3.0 (version 3 of the Solar-Climate Ozone Links CCM), which participated in CCMI, simulates global-mean tropospheric ozone columns of 40.2 DU - approximately 33% larger than the CCMI multi-model mean. Here we introduce an updated version of SOCOLv3.0, "SOCOLv3.1", which includes an improved treatment of ozone sink processes, and results in a reduction in the tropospheric column ozone bias of up to 8 DU, mostly due to the inclusion of N₂O₅ hydrolysis on tropospheric aerosols. As a result of these developments, tropospheric column ozone amounts simulated by SOCOLv3.1 are comparable with several other CCMI models. We apply Gaussian process emulation and sensitivity analysis to understand the remaining ozone bias in SOCOLv3.1. This shows that ozone precursors (nitrogen oxides (NO_x), carbon monoxide, methane and other volatile organic compounds) are responsible for more than 90% of the variance in tropospheric ozone. However, it may not be the emissions inventories themselves that result in the bias, but how the emissions are handled in SOCOLv3.1, and we discuss this in the wider context of the other CCMI models. Given that the emissions data set to be used for phase ₆ of the Coupled Model Intercomparison Project includes approximately 20% more NO_x than the data set used for CCMI, further work is urgently needed to address the challenges of simulating sub-grid processes of importance to tropospheric ozone in the current generation of chemistry-climate models.

Easy to Apply Polyoxazoline-Based Coating for Precise and Long-Term Control of Neural Patterns

Arranging cultured cells in patterns via surface modification is a tool used by biologists to answer questions in a specific and controlled manner. In the past decade, bottom-up neuroscience emerged as a new application, which aims to get a better understanding of the brain via reverse engineering and analyzing elementary circuitry in vitro. Building well-defined neural networks is the ultimate goal. Antifouling coatings are often used to control neurite outgrowth. Because erroneous connectivity alters the entire topology and functionality of minicircuits, the requirements are demanding. Current state-of-the-art coating solutions such as widely used poly(l-lysine)-g-poly(ethylene glycol) (PLL-g-PEG) fail to prevent primary neurons from making undesired connections in long-term cultures. In this study, a new copolymer with greatly enhanced antifouling properties is developed, characterized, and evaluated for its reliability, stability, and versatility. To this end, the following components are grafted to a poly(acrylamide) (PAcrAm) backbone: hexaneamine, to support spontaneous electrostatic adsorption in buffered aqueous solutions, and propyldimethylethoxysilane, to increase the durability via covalent bonding to hydroxylated culture surfaces and antifouling polymer poly(2-methyl-2-oxazoline) (PMOXA). In an assay for neural connectivity control, the new copolymer's ability to effectively prevent unwanted neurite outgrowth is compared to the gold standard, PLL-g-PEG. Additionally, its versatility is evaluated on polystyrene, glass, and poly(dimethylsiloxane) using primary hippocampal and cortical rat neurons as well as C2C12 myoblasts, and human fibroblasts. PAcrAm-g-(PMOXA, NH₂, Si) consistently outperforms PLL-g-PEG with all tested culture surfaces and cell types, and it is the first surface coating which reliably prevents arranged nodes of primary neurons from forming undesired connections over the long term. Whereas the presented work focuses on the proof of concept for the new antifouling coating to successfully and sustainably prevent unwanted connectivity, it is an important milestone for in vitro neuroscience, enabling follow-up studies to engineer neurologically relevant networks. Furthermore, because PAcrAm-g-(PMOXA, NH₂, Si) can be quickly applied and used with various surfaces and cell types, it is an attractive extension to the toolbox for in vitro biology and biomedical engineering.

Atmospheric impacts of the strongest known solar particle storm of 775 AD

Sporadic solar energetic particle (SEP) events affect the Earth’s atmosphere and environment, in particular leading to depletion of the protective ozone layer in the Earth’s atmosphere, and pose potential technological and even life hazards. The greatest SEP storm known for the last 11 millennia (the Holocene) occurred in 774–775 AD, serving as a likely worst-case scenario being 40–50 times stronger than any directly observed one. Here we present a systematic analysis of the impact such an extreme event can have on the Earth’s atmosphere. Using state-of-the-art cosmic ray cascade and chemistry-climate models, we successfully reproduce the observed variability of cosmogenic isotope ¹⁰Be, around 775 AD, in four ice cores from Greenland and Antarctica, thereby validating the models in the assessment of this event. We add to prior conclusions that any nitrate deposition signal from SEP events remains too weak to be detected in ice cores by showing that, even for such an extreme solar storm and sub-annual data resolution, the nitrate deposition signal is indistinguishable from the seasonal cycle. We show that such a severe event is able to perturb the polar stratosphere for at least one year, leading to regional changes in the surface temperature during northern hemisphere winters.

Stimulation of Eryptosis by Caspofungin

Background/Aims: The echinocandin antifungal agent caspofungin has been shown to trigger apoptosis of fungal cells. Beyond that, caspofungin is toxic for host mitochondria. Even though lacking mitochondria, erythrocytes may enter apoptosis-like suicidal erythrocyte death or eryptosis, characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Signaling involved in triggering of eryptosis include increase of cytosolic Ca2+ activity ([Ca2+]i), oxidative stress, ceramide, caspase activation and/or activation of p38 kinase, protein kinase C, and casein kinase. The present study explored, whether caspofungin induces eryptosis and, if so, to shed some light on the cellular mechanisms involved. Methods: Flow cytometry was employed to determine phosphatidylserine exposure at the cell surface from annexin-V-binding, cell volume from forward scatter, [Ca2+]i from Fluo3-fluorescence, ROS formation from DCFDA dependent fluorescence, and ceramide abundance utilizing specific antibodies. Hemolysis was quantified from hemoglobin concentration in the supernatant. Results: A 48 hours exposure of human erythrocytes to caspofungin (≥ 30 µg/ml) significantly increased the percentage of annexin-V-binding cells, significantly decreased forward scatter, significantly enhanced hemolysis, but did not significantly increase Fluo3-fluorescence, DCFDA fluorescence or ceramide abundance. The effect of caspofungin on annexin-V-binding was not significantly blunted by removal of extracellular Ca2+, by inhibition of caspases with pancaspase inhibitor zVAD (10 µM), or by addition of the antioxidant N-acetyl-cysteine (1 mM), p38 kinase inhibitor SB203580 (2 µM) or protein kinase C inhibitor staurosporine (1 µM). The effect of caspofungin on annexin-V-binding was, however, significantly blunted in the presence of casein kinase inhibitor D4476 (10 µM). Conclusions: Caspofungin triggers cell shrinkage and phospholipid scrambling of the erythrocyte cell membrane, an effect possibly involving activation of casein kinase.

Micafungin-Induced Suicidal Erythrocyte Death

Background/Aims: The antifungal drug Micafungin is used for the treatment of diverse fungal infections including candidiasis and aspergillosis. Side effects of Micafungin treatment include microangiopathic hemolytic anemia and thrombocytopenia with microvascular thrombosis. The development of thrombosis may be fostered by stimulation of eryptosis, the suicidal death of erythrocytes characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Triggers of eryptosis include increase of cytosolic Ca2+ activity ([Ca2+]i), oxidative stress, ceramide, activated protein kinase C (PKC), casein kinase 1α or p38 kinase and activated caspases. The present study explored, whether Micafungin induces eryptosis. Methods: Flow cytometry was employed to estimate phosphatidylserine abundance at the erythrocyte surface from annexin-V-binding, cell volume from forward scatter, [Ca2+]i from Fluo3-fluorescence, abundance of reactive oxygen species (ROS) from DCFDA dependent fluorescence, and ceramide abundance at the erythrocyte surface utilizing specific antibodies. Hemolysis was quantified by measuring haemoglobin concentration in the supernatant. Results: A 48 hours exposure of human erythrocytes to Micafungin (10 - 25 µg/ml) significantly increased hemolysis and the percentage of annexin-V-binding cells, and significantly decreased forward scatter. Micafungin (25 µg/ml) did not significantly modify Fluo3-fluorescence, DCFDA fluorescence, or ceramide abundance. The effect of Micafungin on annexin-V-binding was not significantly modified by removal of extracellular Ca2+, by PKC inhibitor staurosporine (1 µM), p38 kinase inhibitor SB203580 (2 µM), casein kinase 1α inhibitor D4476 (10 µM) or pancaspase inhibitor zVAD (10 µM). Conclusions: Micafungin triggers hemolysis and eryptosis with cell shrinkage and phospholipid scrambling of the erythrocyte cell membrane.

Analytic Reviews: Electrophysiologic Testing in the Intensive Care Unit

The role of electrophysiologic concepts and procedures in managing patients with potentially life-threatening ar rhythmias in the intensive care unit is discussed. These patients may be survivors of sudden cardiac arrest or myocardial infarction or may be admitted for syncope or sustained or nonsustained ventricular tachycardia. The value of electrophysiologic testing is discussed in terms of the distinction between wide QRS complex tachycardias that are supraventricular or ventricular in origin and those in which preexcitation syndromes may be important. Drug-induced ventricular arrhythmias are discussed, with specific emphasis on torsades de pointes. Finally, the use of His bundle recordings in pa tients with atrioventricular conduction disturbances is discussed. The methodology of electrophysiologic test ing, including stimulation protocols and interpretation of results, is described.

Anidulafungin-Induced Suicidal Erythrocyte Death

Background/Aims: The novel antifungal drug Anidulafungin is used for the treatment of diverse fungal infections including candidiasis and aspergillosis. The traditional antifungal drug amphotericin B has previously been shown to trigger eryptosis, the suicidal death of erythrocytes characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Triggers of eryptosis include increase of cytosolic Ca2+ activity ([Ca2+]i), oxidative stress, ceramide, activated protein kinase C (PKC), casein kinase 1α or p38 kinase and activated caspases. Inhibitors of eryptosis include nitric oxide (NO). The present study explored, whether Anidulafungin induces eryptosis. Methods: Flow cytometry was employed to estimate phosphatidylserine abundance at the erythrocyte surface from annexin-V-binding, cell volume from forward scatter, [Ca2+]i from Fluo3-fluorescence, abundance of reactive oxygen species (ROS) from DCFDA dependent fluorescence, and ceramide abundance at the erythrocyte surface utilizing specific antibodies. Hemolysis was quantified by measuring haemoglobin concentration in the supernatant. Results: A 48 hours exposure of human erythrocytes to Anidulafungin (1.5 - 6 µg/ml) significantly increased hemolysis and the percentage of annexin-V-binding cells, and significantly decreased forward scatter. Anidulafungin (6 µg/ml) slightly, but significantly inceased Fluo3-fluorescence and the effect of Anidulafungin on annexin-V-binding was slightly, but significantly blunted by removal of extracellular Ca2+. The effect of Anidulafungin on annexin-V-binding was further significantly blunted by the p38 kinase inhibitor SB203580 (2 µM) and NO donor nitroprusside (1 µM). An increase of extracellular K+ concentration significantly blunted the effect of Anidulafungin on cell volume but not on annexin-V-binding. Anidulafungin rather decreased DCFDA fluorescence and the effect of Anidulafungin on annexin-V-binding was not significantly blunted by the antioxidant N-acetylcysteine (1 mM). Moreover, the effect of Anidulafungin on annexin-V-binding was not paralleled by significant increase of ceramide abundance and was not significantly blunted by PKC inhibitor staurosporine (1 µM), casein kinase 1α inhibitor D4476 (10 µM) or pancaspase inhibitor zVAD (10 µM). Conclusions: Anidulafungin triggers hemolysis and eryptosis with cell shrinkage and phospholipid scrambling of the erythrocyte cell membrane, an effect in part due to Ca2+ entry and activation of p38 kinase.

Shikimic acid ozonolysis kinetics of the transition from liquid aqueous solution to highly viscous glass

Ageing of particulate organic matter affects the composition and properties of atmospheric aerosol particles. Driven by temperature and humidity, the organic fraction can vary its physical state between liquid and amorphous solid, or rarely even crystalline. These transitions can influence the reaction kinetics due to limitations of mass transport in such (semi-) solid states, which in turn may influence the chemical ageing of particles containing such compounds. We have used coated wall flow tube experiments to investigate the reaction kinetics of the ozonolysis of shikimic acid, which serves as a proxy for oxygenated, water-soluble organic matter and can form a glass at room temperature. Particular attention was paid to how the presence of water influences the reaction, since it acts a plasticiser and thereby induces changes in the physical state. We analysed the results by means of a traditional resistor model, which assumes steady-state conditions. The ozonolysis rate of shikimic acid is strongly increased in the presence of water, a fact we attribute to the increased transport of O3 and shikimic acid through the condensed phase at lower viscosities. The analysis using the resistor model suggests that the system undergoes both surface and bulk reaction. The second-order rate coefficient of the bulk reaction is 3.7 (+1.5/-3.2) × 10(3) L mol(-1) s(-1). At low humidity and long timescales, the resistor model fails to describe the measurements appropriately. The persistent O3 uptake at very low humidity suggests contribution of a self-reaction of O3 on the surface.

Persistent Water-Nitric Acid Condensate with Saturation Water Vapor Pressure Greater than That of Hexagonal Ice

A laboratory chilled mirror hygrometer (CMH), exposed to an airstream containing water vapor (H2O) and nitric acid (HNO3), has been used to demonstrate the existence of a persistent water-nitric acid condensate that has a saturation H2O vapor pressure greater than that of hexagonal ice (Ih). The condensate was routinely formed on the mirror by removing HNO3 from the airstream following the formation of an initial condensate on the mirror that resembled nitric acid trihydrate (NAT). Typical conditions for the formation of the persistent condensate were a H2O mixing ratio greater than 18 ppm, pressure of 128 hPa, and mirror temperature between 202 and 216 K. In steady-state operation, a CMH maintains a condensate of constant optical diffusivity on a mirror through control of only the mirror temperature. Maintaining the persistent condensate on the mirror required that the mirror temperature be below the H2O saturation temperature with respect to Ih by as much as 3 K, corresponding to up to 63% H2O supersaturation with respect to Ih. The condensate was observed to persist in steady state for up to 16 h. Compositional analysis of the condensate confirmed the co-condensation of H2O and HNO3 and thereby strongly supports the conclusion that the Ih supersaturation is due to residual HNO3 in the condensate. Although the exact structure or stoichiometry of the condensate could not be determined, other known stable phases of HNO3 and H2O are excluded as possible condensates. This persistent condensate, if it also forms in the upper tropical troposphere, might explain some of the high Ih supersaturations in cirrus and contrails that have been reported in the tropical tropopause region.

Ozone uptake on glassy, semi-solid and liquid organic matter and the role of reactive oxygen intermediates in atmospheric aerosol chemistry

Humidity-induced phase transition and formation of reactive oxygen intermediates are important processes in the heterogeneous ozonolysis of unsaturated organic compounds in the atmosphere.

Programmed erythrocyte death following in vitro Treosulfan treatment

BACKGROUND/AIMS

The cytotoxic drug Treosulfan is clinically used for the treatment of malignancy. A common side effect of Treosulfan treatment is anemia. Treosulfan is at least partially effective by triggering apoptosis of tumor cells. Similar to apoptosis of nucleated cells, erythrocytes may enter eryptosis, a suicidal death characterized by cell shrinkage and translocation of phosphatidylserine from the inner to the outer leaflet of the plasma membrane. Triggers of eryptosis include oxidative stress, Ca(2+)-entry and increase of cytosolic Ca(2+)-activity ([Ca(2+)]i). The present study explored whether Treosulfan stimulates eryptosis, which may contribute to development of anemia.

METHODS

Erythrocyte volume was estimated from forward scatter, phosphatidylserine abundance at the erythrocyte surface from Fluorescein isothiocyanate (FITC)-annexin-V-binding, [Ca(2+)]i from Fluo3 fluorescence and reactive oxygen species (ROS) from 2',7'-dichlorodihydrofluorescein diacetate (DCFDA)-fluorescence.

RESULTS

A 48 hours exposure of human erythrocytes to Treosulfan (800 µg/ml) significantly decreased erythrocyte forward scatter, increased the percentage of annexin-V-binding cells, increased [Ca(2+)]i, and increased ROS. The effect of Treosulfan on annexin-V-binding was virtually abrogated by removal of extracellular Ca(2+).

CONCLUSION

Treosulfan stimulates suicidal erythrocyte death or eryptosis at least in part by inducing oxidative stress and stimulating Ca(2+) entry.

Ion depletion near a solution surface: is image-charge repulsion sufficient?

Grazing-incidence Rutherford backscattering and angle-resolved x-ray photoelectron spectrometry are used to determine the ion-concentration profiles near the surface of a solution consisting of a salt (TEABr) in a weakly polar organic liquid (polyethylene glycol) with atomic-layer depth resolution. The predictions of a model, in which ions in solution are repelled from the surface due to a screened Coulomb interaction with their image charge, are in good agreement with measured ion profiles. This contrasts with the behavior of salts in aqueous and highly polar organic solutions.

European emissions of halogenated greenhouse gases inferred from atmospheric measurements

European emissions of nine representative halocarbons (CFC-11, CFC-12, Halon 1211, HCFC-141b, HCFC-142b, HCFC-22, HFC-125, HFC-134a, HFC-152a) are derived for the year 2009 by combining long-term observations in Switzerland, Italy, and Ireland with campaign measurements from Hungary. For the first time, halocarbon emissions over Eastern Europe are assessed by top-down methods, and these results are compared to Western European emissions. The employed inversion method builds on least-squares optimization linking atmospheric observations with calculations from the Lagrangian particle dispersion model FLEXPART. The aggregated halocarbon emissions over the study area are estimated at 125 (106-150) Tg of CO(2) equiv/y, of which the hydrofluorocarbons (HFCs) make up the most important fraction with 41% (31-52%). We find that chlorofluorocarbon (CFC) emissions from banks are still significant and account for 35% (27-43%) of total halocarbon emissions in Europe. The regional differences in per capita emissions are only small for the HFCs, while emissions of CFCs and hydrochlorofluorocarbons (HCFCs) tend to be higher in Western Europe compared to Eastern Europe. In total, the inferred per capita emissions are similar to estimates for China, but 3.5 (2.3-4.5) times lower than for the United States. Our study demonstrates the large benefits of adding a strategically well placed measurement site to the existing European observation network of halocarbons, as it extends the coverage of the inversion domain toward Eastern Europe and helps to better constrain the emissions over Central Europe.