HCOOH in the remote atmosphere: Constraints from Atmospheric Tomography (ATom) airborne observations.

Formic acid (HCOOH) is an important component of atmospheric acidity but its budget is poorly understood, with prior observations implying substantial missing sources. Here we combine pole-to-pole airborne observations from the Atmospheric Tomography Mission (ATom) with chemical transport model (GEOS-Chem CTM) and back trajectory analyses to provide the first global in-situ characterization of HCOOH in the remote atmosphere. ATom reveals sub-100 ppt HCOOH concentrations over most of the remote oceans, punctuated by large enhancements associated with continental outflow. Enhancements correlate with known combustion tracers and trajectory-based fire influences. The GEOS-Chem model underpredicts these in-plume HCOOH enhancements, but elsewhere we find no broad indication of a missing HCOOH source in the background free troposphere. We conclude that missing non-fire HCOOH precursors inferred previously are predominantly short-lived. We find indications of a wet scavenging underestimate in the model consistent with a positive HCOOH bias in the tropical upper troposphere. Observations reveal episodic evidence of ocean HCOOH uptake, which is well-captured by GEOS-Chem; however, despite its strong seawater undersaturation HCOOH is not consistently depleted in the remote marine boundary layer. Over fifty fire and mixed plumes were intercepted during ATom with widely varying transit times and source regions. HCOOH:CO normalized excess mixing ratios in these plumes range from 3.4 to >50 ppt/ppb CO and are often over an order of magnitude higher than expected primary emission ratios. HCOOH is thus a major reactive organic carbon reservoir in the aged plumes sampled during ATom, implying important missing pathways for in-plume HCOOH production.

Validation of the best practice policy statement on urodynamic antibiotic prophylaxis for the high-risk patient in the era of antibiotic stewardship.

AIMS: To validate the recommendations of the Society of Urodynamics, Female Pelvic Medicine, and Urogenital Reconstruction (SUFU) 2017 Best Practice Policy Statement (BPPS) for Urodynamic Antimicrobial Prophylaxis in high-risk patients. METHODS: After institutional review board approval, 489 patients who underwent urodynamics (UDS) in the absence of antibiotic prophylaxis were retrospectively reviewed. Patients were stratified according to the SUFU BPPS risk factors (neurogenic lower urinary tract dysfunction [NLUTD], elevated postvoid residual [PVR], immunosuppression, age over 70, catheter use, and orthopedic implants). χ2 , Fisher's exact test, Student t test, and univariate and multiple logistic regression analyses were used to assess the associations between these risk factors and postprocedural urinary tract infection (UTI). RESULTS: Twenty-two (4.5%) patients developed symptomatic postprocedural UTI. Univariate analysis revealed statistical differences in the incidence of UTI in patients with elevated PVR and NLUTD groups. The variables that were associated with UTI on multivariate analysis were elevated PVR (odds ratio [OR]: 4.91, 95% confidence interval [CI], 1.92-12.56, P = .001) and NLUTD (OR: 4.84, 95% CI, 1.75-3.37, P = .002). The data analysis for all other high-risk groups failed to show significant correlations with UTI on univariate or multivariate analysis. Patients with three risk factors were more likely to develop UTI than patients with 1 or 2 risk factors. No patient developed pyelonephritis, sepsis, or joint infection. CONCLUSIONS: Elevated PVR, NLUTD, and possessing three risk factors were significant predictors for post-UDS UTI. All other risk factors were not associated with postprocedural UTI. Morbidity associated with UTI was low. Antimicrobial prophylaxis for these conditions should be reconsidered.

Constraining remote oxidation capacity with ATom observations.

The global oxidation capacity, defined as the tropospheric mean concentration of the hydroxyl radical (OH), controls the lifetime of reactive trace gases in the atmosphere such as methane and carbon monoxide (CO). Models tend to underestimate the methane lifetime and CO concentrations throughout the troposphere, which is consistent with excessive OH. Approximately half of the oxidation of methane and non-methane volatile organic compounds (VOCs) is thought to occur over the oceans where oxidant chemistry has received little validation due to a lack of observational constraints. We use observations from the first two deployments of the NASA ATom aircraft campaign during July-August 2016 and January-February 2017 to evaluate the oxidation capacity over the remote oceans and its representation by the GEOS-Chem chemical transport model. The model successfully simulates the magnitude and vertical profile of remote OH within the measurement uncertainties. Comparisons against the drivers of OH production (water vapor, ozone, and NO y concentrations, ozone photolysis frequencies) also show minimal bias, with the exception of wintertime NO y . The severe model overestimate of NO y during this period may indicate insufficient wet scavenging and/or missing loss on sea-salt aerosols. Large uncertainties in these processes require further study to improve simulated NO y partitioning and removal in the troposphere, but preliminary tests suggest that their overall impact could marginally reduce the model bias in tropospheric OH. During the ATom-1 deployment, OH reactivity (OHR) below 3 km is significantly enhanced, and this is not captured by the sum of its measured components (cOHRobs) or by the model (cOHRmod). This enhancement could suggest missing reactive VOCs but cannot be explained by a comprehensive simulation of both biotic and abiotic ocean sources of VOCs. Additional sources of VOC reactivity in this region are difficult to reconcile with the full suite of ATom measurement constraints. The model generally reproduces the magnitude and seasonality of cOHRobs but underestimates the contribution of oxygenated VOCs, mainly acetaldehyde, which is severely underestimated throughout the troposphere despite its calculated lifetime of less than a day. Missing model acetaldehyde in previous studies was attributed to measurement uncertainties that have been largely resolved. Observations of peroxyacetic acid (PAA) provide new support for remote levels of acetaldehyde. The underestimate in both model acetaldehyde and PAA is present throughout the year in both hemispheres and peaks during Northern Hemisphere summer. The addition of ocean sources of VOCs in the model increases cOHRmod by 3% to 9% and improves model-measurement agreement for acetaldehyde, particularly in winter, but cannot resolve the model summertime bias. Doing so would require 100 Tg yr-1 of a long-lived unknown precursor throughout the year with significant additional emissions in the Northern Hemisphere summer. Improving the model bias for remote acetaldehyde and PAA is unlikely to fully resolve previously reported model global biases in OH and methane lifetime, suggesting that future work should examine the sources and sinks of OH over land.

Constraints on Aerosol Nitrate Photolysis as a Potential Source of HONO and NO x.

The concentration of nitrogen oxides (NO x) plays a central role in controlling air quality. On a global scale, the primary sink of NO x is oxidation to form HNO3. Gas-phase HNO3 photolyses slowly with a lifetime in the troposphere of 10 days or more. However, several recent studies examining HONO chemistry have proposed that particle-phase HNO3 undergoes photolysis 10-300 times more rapidly than gas-phase HNO3. We present here constraints on the rate of particle-phase HNO3 photolysis based on observations of NO x and HNO3 collected over the Yellow Sea during the KORUS-AQ study in summer 2016. The fastest proposed photolysis rates are inconsistent with the observed NO x to HNO3 ratios. Negligible to moderate enhancements of the HNO3 photolysis rate in particles, 1-30 times faster than in the gas phase, are most consistent with the observations. Small or moderate enhancement of particle-phase HNO3 photolysis would not significantly affect the HNO3 budget but could help explain observations of HONO and NO x in highly aged air.

Effects of Contact Lens Wear on Biometry Measurements for Intraocular Lens Calculations.

OBJECTIVES: To determine the effects of contact lens (CL) wear on biometry measurements for cataract surgery and whether a CL hiatus can reduce the prediction error of intraocular lens (IOL) calculations. METHODS: Retrospective, interventional case series of eyes that received repeat biometry measurements for IOL calculations after discontinuing hard or soft CLs for at least 14 days. PRIMARY OUTCOME MEASURES: intersession change in axial length, average keratometry, astigmatism, and axis. SECONDARY OUTCOME MEASURES: change in recommended IOL power and toricity, postoperative refraction prediction error. RESULTS: Thirty-two eyes of 16 patients had a mean duration of CL wear (12 hard and 20 soft) of 39.5 years (range, 29-55 years) and mean CL hiatus duration of 25 days (range, 14-56 days). Mean absolute intersession change in axial length was 0.016 mm (range, 0-0.05 mm), average keratometry 0.31 D (range, 0.02-1.01 D), astigmatism 0.41 D (range, 0.01-1.10 D), and axis 6.3° (range, 0-28°). The IOL power predicting the lowest postoperative spherical equivalent changed for 17 of 32 eyes (by 0.5 D for 12 eyes and 1.0 D for five eyes). Recommended IOL toricity changed for nine of 14 eyes (by 0.75 D for six eyes and 1.50 D for three eyes). The median absolute prediction error of IOL calculations was 0.69 D (range, 0.19-2.93 D) before and 0.57 D (range, 0.01-2.82 D) after the CL hiatus (P=0.16). CONCLUSIONS: Contact lens wear may affect biometry measurements and subsequent IOL power and toricity selection. For some eyes, repeating biometry measurements after a CL hiatus may improve the accuracy of IOL calculations.

Effect of thermal pulsation treatment on tear film parameters in dry eye disease patients.

PURPOSE: The goal of this study was to evaluate the effect of thermal pulsation treatment on tear film parameters, specifically osmolarity and matrix metalloproteinase-9 (MMP-9), in patients with meibomian gland dysfunction (MGD) and dry eye disease (DED). METHODS: A single-center review of 189 eyes that underwent thermal pulsation treatment was performed. Data were collected on pre and posttreatment osmolarity, MMP-9, tear break-up time (TBUT), and ocular surface disease index (OSDI) score. Statistical analyses were performed to detect any significant differences after treatment. RESULTS: Thermal pulsation treatment led to significant improvements in TBUT (mean increase from 4.5 to 8.5 seconds [P<0.001]), OSDI score (mean decrease from 50.5 to 41.6 [P=0.024]), and MMP-9 (50% positive rate pretreatment compared to 26% positive rate post treatment [P<0.0001]). In the subset of patients who had a baseline osmolarity >307 mOsm/L (ie, diagnostic for DED), there was a significant improvement in the mean tear osmolarity from 317.1 to 306.6 mOsms/L after treatment (P=0.002). CONCLUSION: Treating MGD is an important component of caring for the DED patient. Thermal pulsation treatment can improve MMP-9 levels on the ocular surface of patients with MGD and DED, as well as improve osmolarity in those with abnormal initial values. The present study suggests that meibomian glands play an important role in tear film dynamics and, as such, effective therapy such as thermal pulsation treatment aimed at improving meibomian gland health, can aid the restoration of normal tear film parameters and decrease patient symptoms of DED and MGD.

Identification of Potentially Pathogenic Variants in the Posterior Polymorphous Corneal Dystrophy 1 Locus.

Posterior polymorphous corneal dystrophy 1 (PPCD1) is a genetic disorder that affects corneal endothelial cell function and leads to loss of visual acuity. PPCD1 has been linked to a locus on chromosome 20 in multiple families; however, Sanger sequencing of protein-coding genes in the consensus region failed to identify any causative missense mutations. In this study, custom capture probes were utilized for targeted next-generation sequencing of the linked region in a previously reported family with PPCD1. Variants were detected through two bioinformatics pipelines and filtered according to multiple criteria. Additionally, a high-resolution microarray was used to detect copy number variations. No non-synonymous variants in the protein-coding region of annotated genes were identified. However, 12 single nucleotide variants in 10 genes, and 9 indels in 7 genes met the filtering criteria and were considered candidate variants for PPCD1. Eleven single nucleotide variants were confirmed by Sanger sequencing, including 2 synonymous variants and 9 non-coding variants, in 9 genes. One microdeletion was detected in an intron of OVOL2 by microarray but was subsequently not identified by PCR. Using a comprehensive next-generation sequencing approach, a total of 16 genes containing single nucleotide variants or indels that segregated with the affected phenotype in an affected family previously mapped to the PPCD1 locus were identified. Screening of these candidate genes in other families previously mapped to the PPCD1 locus will likely result in the identification of the genetic basis of PPCD1.

Famous.

A 62-year-old woman with multiple sclerosis experienced painless loss of vision in both eyes after starting fingolimod. Fundus examination revealed bilateral macular edema confirmed by optical coherence tomography. Fingolimod was discontinued, and a topical nonsteroidal inflammatory drug and corticosteroid were initiated. Within 2 months, vision returned to baseline with complete resolution of the macular edema.

Investigation of a potential HCHO measurement artifact from ISOPOOH.

Recent laboratory experiments have shown that a first generation isoprene oxidation product, ISOPOOH, can decompose to methyl vinyl ketone (MVK) and methacrolein (MACR) on instrument surfaces, leading to overestimates of MVK and MACR concentrations. Formaldehyde (HCHO) was suggested as a decomposition co-product, raising concern that in situ HCHO measurements may also be affected by an ISOPOOH interference. The HCHO measurement artifact from ISOPOOH for the NASA In Situ Airborne Formaldehyde instrument (ISAF) was investigated for the two major ISOPOOH isomers, (1,2)-ISOPOOH and (4,3)-ISOPOOH, under dry and humid conditions. The dry conversion of ISOPOOH to HCHO was 3±2% and 6±4% for (1,2)-ISOPOOH and (4,3)-ISOPOOH, respectively. Under humid (RH= 40-60%) conditions, conversion to HCHO was 6±4% for (1,2)-ISOPOOH and 10±5% for (4,3)-ISOPOOH. The measurement artifact caused by conversion of ISOPOOH to HCHO in the ISAF instrument was estimated for data obtained on the 2013 September 6 flight of the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) campaign. Prompt ISOPOOH conversion to HCHO was the source for <4% of the observed HCHO, including in the high-isoprene boundary layer. Time-delayed conversion, where previous exposure to ISOPOOH affects measured HCHO later in flight, was conservatively estimated to be < 10% of observed HCHO and is significant only when high ISOPOOH sampling periods immediately precede periods of low HCHO.

Ocular surface, fornix, and eyelid rehabilitation in Boston type I keratoprosthesis patients with mucous membrane disease.

PURPOSE: To understand the efficacy of various approaches for ocular surface reconstruction in eyes with implanted Boston Type I keratoprosthesis. METHODS: All eyes implanted with a Boston Type I keratoprosthesis over a 9-year period by a single surgeon were reviewed. Any case in which mucosal rehabilitation was performed was included in the study sample. The type, number, approach, and outcome for all eyelid and ocular surface procedures were assessed. RESULTS: A total of 22 mucosal surface surgeries were performed before, concurrent with, and after implantation of 11 keratoprostheses and 1 penetrating keratoplasty (after keratoprosthesis removal) in 9 eyes of 9 patients. Most of the ocular surface reconstructive surgeries (81.8%; 18/22) were performed at the time of or following keratoprosthesis implantation, with the most common indication being corneal stromal necrosis (44.4%; 8/18). Free grafting and simple advancement resulted in graft retraction for each case, and pedicle or bucket handle flaps resulted in a stable vascularized graft for half of the cases. Graft retraction occurred in 6 of the 9 eyes in this study, including in all 5 eyes of patients with Stevens Johnsons syndrome (SJS). CONCLUSIONS: Free grafting and simple advancement flaps do not appear to be effective for rehabilitation in these eyes. However, even vascularized pedicle and bucket handle flaps retracted 50% of the time. Individuals with SJS were more likely to both require conjunctival rehabilitation after keratoprosthesis surgery and develop graft retraction in the course of management.

Posterior amorphous corneal dystrophy is associated with a deletion of small leucine-rich proteoglycans on chromosome 12.

Posterior amorphous corneal dystrophy (PACD) is a rare, autosomal dominant disorder affecting the cornea and iris. Next-generation sequencing of the previously identified PACD linkage interval on chromosome 12q21.33 failed to yield a pathogenic mutation. However, array-based copy number analysis and qPCR were used to detect a hemizygous deletion in the PACD linkage interval containing 4 genes encoding small leucine-rich proteoglycans (SLRPs): KERA, LUM, DCN, and EPYC. Two other unrelated families with PACD also demonstrated deletion of these SLRPs, which play important roles in collagen fibrillogenesis and matrix assembly. Given that these genes are essential to the maintenance of corneal clarity and the observation that knockout murine models display corneal phenotypic similarities to PACD, we provide convincing evidence that PACD is associated with haploinsufficiency of these SLRPs.

A controlling role for the air-sea interface in the chemical processing of reactive nitrogen in the coastal marine boundary layer.

The lifetime of reactive nitrogen and the production rate of reactive halogens in the marine boundary layer are strongly impacted by reactions occurring at aqueous interfaces. Despite the potential importance of the air-sea interface in serving as a reactive surface, few direct field observations are available to assess its impact on reactive nitrogen deposition and halogen activation. Here, we present direct measurements of the vertical fluxes of the reactant-product pair N2O5 and ClNO2 to assess the role of the ocean surface in the exchange of reactive nitrogen and halogens. We measure nocturnal N2O5 exchange velocities (Vex = -1.66 ± 0.60 cm s(-1)) that are limited by atmospheric transport of N2O5 to the air-sea interface. Surprisingly, vertical fluxes of ClNO2, the product of N2O5 reactive uptake to concentrated chloride containing surfaces, display net deposition, suggesting that elevated ClNO2 mixing ratios found in the marine boundary layer are sustained primarily by N2O5 reactions with aerosol particles. Comparison of measured deposition rates and in situ observations of N2O5 reactive uptake to aerosol particles indicates that N2O5 deposition to the ocean surface accounts for between 26% and 42% of the total loss rate. The combination of large Vex, N2O5 and net deposition of ClNO2 acts to limit NOx recycling rates and the production of Cl atoms by shortening the nocturnal lifetime of N2O5. These results indicate that air-sea exchange processes account for as much as 15% of nocturnal NOx removal in polluted coastal regions and can serve to reduce ClNO2 concentrations at sunrise by over 20%.

Transition metal associations with primary biological particles in sea spray aerosol generated in a wave channel.

In the ocean, breaking waves generate air bubbles which burst at the surface and eject sea spray aerosol (SSA), consisting of sea salt, biogenic organic species, and primary biological aerosol particles (PBAP). Our overall understanding of atmospheric biological particles of marine origin remains poor. Here, we perform a control experiment, using an aerosol time-of-flight mass spectrometer to measure the mass spectral signatures of individual particles generated by bubbling a salt solution before and after addition of heterotrophic marine bacteria. Upon addition of bacteria, an immediate increase occurs in the fraction of individual particle mass spectra containing magnesium, organic nitrogen, and phosphate marker ions. These biological signatures are consistent with 21% of the supermicrometer SSA particles generated in a previous study using breaking waves in an ocean-atmosphere wave channel. Interestingly, the wave flume mass spectral signatures also contain metal ions including silver, iron, and chromium. The nascent SSA bioparticles produced in the wave channel are hypothesized to be as follows: (1) whole or fragmented bacterial cells which bioaccumulated metals and/or (2) bacteria-derived colloids or biofilms which adhered to the metals. This study highlights the potential for transition metals, in combination with specific biomarkers, to serve as unique indicators for the presence of marine PBAP, especially in metal-impacted coastal regions.

Microbial keratitis after Boston type I keratoprosthesis implantation: incidence, organisms, risk factors, and outcomes.

PURPOSE: To identify the incidence of and risk factors for microbial keratitis after implantation of the Boston type I keratoprosthesis (Massachusetts Eye and Ear Infirmary, Boston, MA). DESIGN: Retrospective, single-surgeon consecutive case series. PARTICIPANTS: A total of 105 patients (125 keratoprosthesis procedures in 110 eyes) who underwent Boston type I keratoprosthesis implantation at the Jules Stein Eye Institute between May 1, 2004, and April 1, 2012. METHODS: Data regarding ocular history, relevant intraoperative data, postoperative management, and outcomes were collected for each procedure. Risk factor analyses were performed using the Fisher exact test, log-rank test, and hazard ratio (HR). MAIN OUTCOME MEASURES: Incidence of microbial keratitis, organisms responsible, risk factors, and outcomes. RESULTS: During the period under review, 20 presumed infectious infiltrates were diagnosed in 15 eyes (13.6%) of 15 patients (14.3%), for a rate of 0.073 infections per eye-year. The rate of culture-positive bacterial keratitis was 0.022 infections per eye-year, and the rate of culture-positive fungal keratitis was 0.015 infections per eye-year. Topical vancomycin use, topical steroid use, and contact lens wear did not increase the incidence of infectious keratitis, but prolonged vancomycin use was associated with an increased risk for fungal keratitis and infectious keratitis overall. Persistent corneal epithelial defect formation also was associated with an increased incidence of fungal keratitis and infectious keratitis overall. There were no cases of endophthalmitis resulting from infectious keratitis. CONCLUSIONS: Infectious keratitis develops in 13.6% of eyes after keratoprosthesis implantation, with a similar rate of culture-positive bacterial and fungal keratitis. The observed rate of microbial keratitis suggests the need for additional topical antimicrobial prophylaxis after keratoprosthesis implantation in eyes at higher risk, such as those with persistent corneal epithelial defect formation or prolonged vancomycin use.

Bringing the ocean into the laboratory to probe the chemical complexity of sea spray aerosol.

The production, size, and chemical composition of sea spray aerosol (SSA) particles strongly depend on seawater chemistry, which is controlled by physical, chemical, and biological processes. Despite decades of studies in marine environments, a direct relationship has yet to be established between ocean biology and the physicochemical properties of SSA. The ability to establish such relationships is hindered by the fact that SSA measurements are typically dominated by overwhelming background aerosol concentrations even in remote marine environments. Herein, we describe a newly developed approach for reproducing the chemical complexity of SSA in a laboratory setting, comprising a unique ocean-atmosphere facility equipped with actual breaking waves. A mesocosm experiment was performed in natural seawater, using controlled phytoplankton and heterotrophic bacteria concentrations, which showed SSA size and chemical mixing state are acutely sensitive to the aerosol production mechanism, as well as to the type of biological species present. The largest reduction in the hygroscopicity of SSA occurred as heterotrophic bacteria concentrations increased, whereas phytoplankton and chlorophyll-a concentrations decreased, directly corresponding to a change in mixing state in the smallest (60-180 nm) size range. Using this newly developed approach to generate realistic SSA, systematic studies can now be performed to advance our fundamental understanding of the impact of ocean biology on SSA chemical mixing state, heterogeneous reactivity, and the resulting climate-relevant properties.

Systems genetics analysis of gene-by-environment interactions in human cells.

Gene by environment (GxE) interactions are clearly important in many human diseases, but they have proven to be difficult to study on a molecular level. We report genetic analysis of thousands of transcript abundance traits in human primary endothelial cell (EC) lines in response to proinflammatory oxidized phospholipids implicated in cardiovascular disease. Of the 59 most regulated transcripts, approximately one-third showed evidence of GxE interactions. The interactions resulted primarily from effects of distal-, trans-acting loci, but a striking example of a local-GxE interaction was also observed for FGD6. Some of the distal interactions were validated by siRNA knockdown experiments, including a locus involved in the regulation of multiple transcripts involved in the ER stress pathway. Our findings add to the understanding of the overall architecture of complex human traits and are consistent with the possibility that GxE interactions are responsible, in part, for the failure of association studies to more fully explain common disease variation.