Characterization of Highly Oxidized Molecules in Fresh and Aged Biogenic Secondary Organic Aerosol.

In this work, highly oxidized multifunctional molecules (HOMs) in fresh and aged secondary organic aerosol (SOA) derived from biogenic precursors are characterized with high-resolution mass spectrometry. Fresh SOA was generated by mixing ozone with a biogenic precursor (ß-pinene, limonene, α-pinene) in a flow tube reactor. Aging was performed by passing the fresh SOA through a photochemical reactor where it reacted with hydroxyl radicals. Although these aerosols were as a whole not highly oxidized, molecular analysis identified a significant number of HOMs embedded within it. HOMs in fresh SOA consisted mostly of monomers and dimers, which is consistent with condensation of extremely low-volatility organic compounds (ELVOCs) that have been detected in the gas phase in previous studies and linked to SOA particle formation. Aging caused an increase in the average number of carbon atoms per molecule of the HOMs, which is consistent with particle phase oxidation of (less oxidized) oligomers already existing in fresh SOA. HOMs having different combinations of oxygen-to-carbon ratio, hydrogen-to-carbon ratio and average carbon oxidation state are discussed and compared to low volatility oxygenated organic aerosol (LVOOA), which has been identified in ambient aerosol based on average elemental composition but not fully understood at a molecular level. For the biogenic precursors and experimental conditions studied, HOMs in fresh biogenic SOA have molecular formulas more closely resembling LVOOA than HOMs in aged SOA, suggesting that aging of biogenic SOA is not a good surrogate for ambient LVOOA.

Dantrolene for cerebral vasospasm after subarachnoid haemorrhage: a randomised double blind placebo-controlled safety trial.

BACKGROUND: Dantrolene is neuroprotective in animal models and may attenuate cerebral vasospasm (cVSP) in human aneurysmal subarachnoid haemorrhage (aSAH). We evaluated safety, feasibility and tolerability of intravenous dantrolene (IV-D) in patients with aSAH. METHODS: In this single-centre, randomised, double blind, placebo-controlled trial, 31 patients with aSAH were randomised to IV-D 1.25 mg every 6 h for 7 days (n=16) or equiosmolar free water/5% mannitol (placebo; n=15). Primary safety end points were incidence of hyponatraemia (sNa≤132 mmol/L) and liver toxicity (proportion of patients alanine transaminase, aspartate aminotransferase and AlkPhos >5× upper-limit-of-normal). Secondary end points included tolerability, systemic hypotension and intracranial hypertension. Efficacy was explored for clinical/radiological cVSP, delayed cerebral ischaemia (DCI), and 3-month functional outcomes. Quantitative analyses of angiograms and daily transcranial Doppler (TCD) were performed. RESULTS: Between IV-D versus placebo, no differences were observed in the primary outcomes (hyponatremia 44% vs 67% (p=0.29); liver toxicity 6% vs 0% (p=1.0)). Three patients in the IV-D versus two in the placebo group had severe adverse events possibly attributable to infusion and reached stop criteria: one IV-D patient developed liver toxicity; two patients in each group developed brain oedema requiring osmotherapy. The majority of adverse events were not related to infusion (17 vs 5 (RR 2.2; 95% CI 0.7 to 6.7; p=0.16) in IV-D vs placebo). No differences in any categorical cVSP outcomes, DCI, 3-month outcomes or quantitative angiogram and TCD analyses were seen in this small safety trial not powered to detect efficacy. CONCLUSIONS: In this small trial, IV-D after aSAH was feasible, tolerable and safe. TRIAL REGISTRATION NUMBER: http://clinicaltrials.gov NCT01024972.

Rapid unexpected brain herniation in association with renal replacement therapy in acute brain injury: caution in the neurocritical care unit.

INTRODUCTION: We aim to raise awareness for the potential for rapid brain edema and herniation in acutely brain-injured patients undergoing renal replacement therapy (RRT), including one case undergoing continuous veno-venous hemofiltration. Dialysis disequilibrium syndrome (DDS) may have been a possible cause for the brain edema. METHODS: We retrospectively reviewed four consecutive neurocritically ill patients in acute renal failure undergoing RRT between 2011 and 2013. Imaging, blood pressure, and laboratory data pre-, during, and post-RRT are presented in graphical form. We performed an extensive literature review. RESULTS: All patients suffered rapidly progressive herniation and death from global brain edema closely related in time to RRT, without other identifiable causes even after detailed review by three neurointensivists. Common clinical symptoms included sudden onset fixed and dilated pupils with apnea, consistent with brain stem compression. Herniation was not reversed by high-dose osmotherapy, and all patients died. Our detailed literature review provides plausible mechanisms for DDS as the most likely cause for our patients' brain edema. CONCLUSIONS: Even today, sudden brain edema and herniation may occur in association with RRT in neurocritically ill patients. We call for the establishment of RRT guidelines in patients with acute neurological injuries.

Quantifying Residues from Postharvest Propylene Oxide Fumigation of Almonds and Walnuts.

A novel analytical approach involving solvent extraction with methyl tert-butyl ether (MTBE) followed by GC was developed to quantify residues that result from the postharvest fumigation of almonds and walnuts with propylene oxide (PPO). Verification and quantification of PPO, propylene chlorohydrin (PCH) [1-chloropropan-2-ol (PCH-1) and 2-chloropropan-1-ol (PCH-2)], and propylene bromohydrin (PBH) [1-bromopropan-2-ol (PBH-1) and 2-bromopropan-1-ol (PBH-2)] was accomplished with a combination of electron impact ionization MS (EIMS), negative ion chemical ionization MS (NCIMS), and electron capture detection (ECD). Respective GC/EIMS LOQs for PPO, PCH-1, PCH-2, PBH-1, and PBH-2 in MTBE extracts were [ppm (µg/g nut)] 0.9, 2.1, 2.5, 30.3, and 50.0 for almonds and 0.8, 2.2, 2.02, 41.6, and 45.7 for walnuts. Relative to GC/EIMS, GC-ECD analyses resulted in no detection of PPO, similar detector responses for PCH isomers, and >100-fold more sensitive detection of PBH isomers. NCIMS did not enhance detection of PBH isomers relative to EIMS and was, respectively, approximately 20-, 5-, and 10-fold less sensitive to PPO, PCH-1, and PCH-2. MTBE extraction efficiencies were >90% for all analytes. The 10-fold concentration of MTBE extracts yielded recoveries of 85-105% for the PBH isomers and a concomitant decrease in LODs and LOQs across detector types. The recoveries of PCH isomers and PPO in the MTBE concentrate were relatively low (approximately 50 to 75%), which confound improvements in LODs and LOQs regardless of detector type.

Comparison of a low, fixed dose and a high, weight-based dose of recombinant factor VIIa in the treatment of warfarin-associated intracranial hemorrhage.

BACKGROUND: Recombinant activated Factor VII (rFVIIa) can be used for rapid INR normalization in patients with warfarin-associated intracranial hemorrhage (WA-ICH); however, the optimal dose to normalize INR has not been established. METHODS: This is a retrospective review comparing two rFVIIa hospital protocols for WA-ICH [weight-based dose (80 mcg/kg) or fixed dose (2 mg)]. Primary endpoint was the percentage of patients with INR reversal (INR <1.3) at the next INR draw and the need for further doses of rFVIIa. Secondary endpoints included time to documented INR reversal and sustained INR normalization, morbidity, mortality, change in hematoma size, cost, and adverse drug reactions. RESULTS: Twenty-nine patients were included in each group. The weight-based group received a mean dose of 78.9 ± 21 mcg/kg versus 26.6 ± 8 mcg/kg in the fixed dose group. More patients in the fixed dose protocol achieved documented INR reversal than those in the weight-based group (92.6 vs 72.4 %, p = 0.19). The weight-based group achieved INR normalization in 229.5 [102, 331] minutes versus 165 [83, 447] minutes in the fixed dose group (p=0.02). Time to sustained INR normalization was similar in both groups. Four patients in the fixed dose group received an additional dose of 1 mg per hospital protocol. With the exception of medication acquisition cost savings of about $4,300 per patient who received fixed dose protocol, all other endpoints were similar between groups. CONCLUSIONS: A low, fixed dose of rFVIIa appears to be as effective as a high, weight-based dose in achieving INR normalization in patients with WA-ICH.

Severe leukoaraiosis portends a poor outcome after traumatic brain injury.

BACKGROUND AND PURPOSE: It is now well accepted that traumatic white matter injury constitutes a critical determinant of post-traumatic functional impairment. However, the contribution of preexisting white matter rarefaction on outcome following traumatic brain injury (TBI) is unknown. Hence, we sought to determine whether the burden of preexisting leukoaraiosis of presumed ischemic origin is independently associated with outcome after TBI. METHODS: We retrospectively analyzed consecutive, prospectively enrolled patients of ≥50 years (n = 136) who were admitted to a single neurological/trauma intensive care unit. Supratentorial white matter hypoattenuation on head CT was graded on a 5-point scale (range 0-4) reflecting increasing severity of leukoaraiosis. Outcome was ascertained according to the modified Rankin Scale (mRS) and Glasgow outcome scale (GOS) at 3 and 12 months, respectively. RESULTS: After adjustment for other factors, leukoaraiosis severity was significantly associated with a poor outcome at 3 and 12 months defined as mRS 3-6 and GOS 1-3, respectively. The independent association between leukoaraiosis and poor outcome remained when the analysis was restricted to patients who survived up to 3 months, had moderate-to-severe TBI [enrollment Glasgow Coma Scale (GCS) ≤12; p = 0.001], or had mild TBI (GCS 13-15; p = 0.002), respectively. CONCLUSION: We provide first evidence that preexisting cerebral small vessel disease independently predicts a poor functional outcome after closed head TBI. This association is independent of other established outcome predictors such as age, comorbid state as well as intensive care unit complications and interventions. This knowledge may help improve prognostic accuracy, clinical management, and resource utilization.

Molecular transformations accompanying the aging of laboratory secondary organic aerosol.

The aging of fresh secondary organic aerosol (SOA), formed in a flow tube reactor by α-pinene ozonolysis, was studied by passing the fresh SOA into a second chamber for reaction with high levels of the hydroxyl radical. Two types of experiments were performed: (1) injection of a short plug of fresh SOA into the second chamber, where the particle mass and average O/C mole ratio were measured as a function of time after injection, and (2) injection of a continuous stream of fresh SOA into the second chamber, where particles were collected on a filter over a period of time for off line analysis by high performance mass spectrometry. These setups allowed the chemistry of SOA aging to be elucidated. The particle mass decreased and average O/C ratio increased with increasing aging time. Aged SOA showed an oligomer distribution shifted to lower molecular weight (fragmentation) and molecular formulas with higher O/C and lower H/C ratios (functionalization). Carbon oxidation states of individual molecules were higher for aged SOA, 0 to +2, than fresh SOA, -1 to 0. Tandem mass spectrometry of oligomers from fresh SOA showed small neutral losses associated with less oxidized functional groups such as aldehydes and ketones, while oligomers from aged SOA showed losses associated with more highly oxidized groups such as acids and peroxyacids. Product ion spectra of fresh SOA showed monomer building blocks with formulas corresponding to primary ozonolysis products such as pinic and pinonic acids, whereas aged SOA monomer building blocks corresponded to extremely oxidized products such as dimethyltricarballylic acid.

Thermodynamics of oligomer formation: implications for secondary organic aerosol formation and reactivity.

Dimers and higher order oligomers, whether in the gas or particle phase, can affect important atmospheric processes such as new particle formation, and gas-particle partitioning. In this study, the thermodynamics of dimer formation from various oxidation products of α-pinene ozonolysis are investigated using a combination of Monte Carlo configuration sampling, semi-empirical and density functional theory (DFT) quantum mechanics, and continuum solvent modeling. Favorable dimer formation pathways are found to exist in both gas and condensed phases. The free energies of dimer formation are used to calculate equilibrium constants and expected dimer concentrations under a variety of conditions. In the gas phase, favorable pathways studied include formation of non-covalent dimers of terpenylic acid and/or cis-pinic acid and a covalently-bound peroxyhemiacetal. Under atmospherically relevant conditions, only terpenylic acid forms a dimer in sufficient quantities to contribute to new particle formation. Under conditions typically used in laboratory experiments, several dimer formation pathways may contribute to particle formation. In the condensed phase, non-covalent dimers of terpenylic acid and/or cis-pinic acid and covalently-bound dimers representing a peroxyhemiacetal and a hydrated aldol are favorably formed. Dimer formation is both solution and temperature dependent. A water-like solution appears to promote dimer formation over methanol- or acetonitrile-like solutions. Heating from 298 K to 373 K causes extensive decomposition back to monomers. Dimers that are not favorably formed in either the gas or condensed phase include hemi-acetal, ester, anhydride, and the di(α-hydroxy) ether.

Frequency and impact of intensive care unit complications on moderate-severe traumatic brain injury: early results of the Outcome Prognostication in Traumatic Brain Injury (OPTIMISM) Study.

BACKGROUND: Known predictors of adverse outcomes in patients with moderate-severe TBI (msTBI) explain only a relatively small proportion of patient-related outcomes. The frequency and impact of intensive care unit complications (ICU-COMPL) on msTBI-associated outcomes are poorly understood. METHODS: In 213 consecutive msTBI patients admitted to a Level I Trauma Center neuro trauma ICU, twenty-eight ICU-COMPL (21 medical and 7 neurological) were prospectively collected and adjudicated by group consensus, using pre-defined criteria. We determined frequencies, and explored associations of ICU-COMPL and hospital discharge outcomes using multivariable logistic regression. RESULTS: The average age of the study sample was 53 years, and the median presenting Glasgow Coma Scale and Injury Severity Scores were 5 and 27, respectively. Hyperglycemia (79%), fever (62%), systemic inflammatory response syndrome (60%), and hypotension requiring vasopressors (42%) were the four most common medical ICU-COMPL. Herniation (39%), intracranial rebleed (39%), and brain edema requiring osmotherapy (37%) were the three most common neurological ICU-COMPL. After adjusting for admission variables, duration of ventilation, and ICU length-of-stay, patients with brain edema (OR 5.8; 95% CI 2, 16.7) had a significantly increased odds for dying during hospitalization whereas patients with hospital-acquired urinary tract infection (UTI) had a decreased odds (OR 0.05; 95% CI 0.005, 0.6). Sensitivity analysis revealed that UTI occurred later, suggesting a non-causal association with survival. Brain herniation (OR 15.7; 95% CI 2.6, 95.4) was associated with an unfavorable functional status (GOS 1-3). CONCLUSION: ICU-COMPL are very common after msTBI, have a considerable impact on short-term outcomes, and should be considered in the prognostication of these high risk patients. Survival associations of time-dependent complications warrant cautious interpretation.

Self-fulfilling prophecies through withdrawal of care: do they exist in traumatic brain injury, too?

OBJECTIVE: We examined factors associated with withdrawal of care (WOC) in moderate-severe traumatic brain injury (msTBI) patients, and how WOC may affect short-term mortality and receipt of neurosurgery. Variability in msTBI-related outcome prognostication by clinicians from different specialties was also assessed. METHODS: Rates of WOC, factors associated with WOC, and the relation between WOC and in-hospital case-fatality rate (CFR) and neurosurgery were determined in 232 prospectively enrolled msTBI patients in the ongoing OPTIMISM Study at a level-1 trauma center. In a concomitant web-based survey with clinical vignettes, outcome prognostication comfort, treatment aggressiveness, and WOC recommendations were examined among 106 respondents from neurology, neurocritical care, neurosurgery, trauma and anesthesia/critical care. RESULTS: The average age of the study sample was 53 years, with a median Glasgow Coma Scale of 6. The in-hospital CFR was 36 and 68 % of patients had WOC. Factors independently associated with WOC were advanced age, pupillary reactivity, lower intensive care unit-length-of-stay, pre- and in-hospital cardiac arrest, herniation, intracranial pressure crisis, and pre-existing endocrine disease. Inclusion of WOC in our multivariable regression model predicting in-hospital CFRs negated all other variables. Survey results suggested that in younger patients, some clinicians prognosticated overly pessimistically based upon data available at the time of presentation. CONCLUSION: In our msTBI cohort, WOC was the most important predictor of in-hospital mortality. We identified several important independent predictors of WOC. Large within-center variability in msTBI outcome prognostication with varying levels of possible clinical nihilism exists, which may form the basis of self-fulfilling prophecies.

Online characterization of particles and gases with an ambient electrospray ionization source.

Methods for online characterization and quantification of gas- and particle-phase species greatly facilitate the study of aerosol particle formation and reaction mechanisms. An online method for aerosol analysis has been developed by altering a conventional electrospray ionization mass spectrometer to direct the aerosol flow through the nebulizing gas inlet. Interaction between the aerosol and electrospray droplets produces ions that are subsequently analyzed by MS or MS/MS with a quadrupole ion trap mass analyzer. Performance is assessed using both particle-phase (cesium iodide, glycine) and gas-phase (dimethylamine, dimethylnapthylamine) analytes as well as a secondary organic aerosol (SOA) produced by ozonolysis of α-pinene. Analyte signal intensity is strongly dependent on solubility in the electrospray solvent, suggesting that the predominant ionization mechanism involves extraction of the analyte into the electrospray droplets. For gas-phase analytes, gas-phase charge transfer also appears to play a minor role in ion formation. As currently configured, the source is capable of characterizing oligomers in a SOA at a mass loading of <30 µg/m(3) and quantifying alkyl amine concentrations between approximately 8 ppb and 1 ppm.

Predicting mortality in moderate-severe TBI patients without early withdrawal of life-sustaining treatments including ICU complications: The MYSTIC-score.

PURPOSE: To develop and internally validate the MortalitY in Moderate-Severe TBI plus ICU Complications (MYSTIC)-Score to predict in-hospital mortality of msTBI patients without early (<24 h) withdrawal-of-life-sustaining treatments. METHODS: We analyzed data from a Neuro-Trauma Intensive Care Unit prospectively collected between 11/2009-5/2019. Consecutive adult msTBI patients were included if Glasgow Coma Scale≤12, and neither died nor had withdrawal-of-life-sustaining treatments within 24 h of admission (n = 485). Using univariate and multivariable logistic regression in a random-split cohort approach (2/3 derivation;1/3 validation), we identified independent predictors of in-hospital mortality while adjusting for validated predictors of mortality (IMPACT-variables). We constructed the MYSTIC-Score and examined discrimination and calibration. RESULTS: The MYSTIC-Score included the ICU complications brain edema, herniation, systemic inflammatory response syndrome, sepsis, acute kidney injury, cardiac arrest, and urinary tract infection. In the derivation cohort(n = 324), discrimination and calibration were excellent (area-under-the-receiver-operating-curve [AUC-ROC] = 0.95;Hosmer-Lemeshow p-value = 0.09, with p > 0.05 indicating good calibration). Internal validation revealed an AUC-ROC = 0.93 and Hosmer-Lemeshow-p-value = 0.76 (n = 161). CONCLUSIONS: Certain ICU complications are independent predictors of in-hospital mortality and strengthen outcome prediction in msTBI when combined with validated admission predictors of mortality. However, external validation is needed to determine robustness and practical applicability of our model given the high potential for residual confounders.

Molecular composition of monoterpene secondary organic aerosol at low mass loading.

The molecular composition of secondary organic aerosol (SOA) from the ozonolysis of monoterpenes (α-pinene and ß-pinene) was studied by liquid chromatography mass spectrometry and high-resolution Fourier transform ion cyclotron resonance mass spectrometry techniques, both employing electrospray ionization (ESI). SOA particles were generated in a flow tube reactor with a reaction time of 23 s. A microsampling assembly in combination with ESI-FTICR analysis permitted SOA with a mass loading as low as 3.5 µg/m(3) to be characterized with high accuracy and precision mass analysis. Hundreds of product molecular formulas were identified that were common to all mass loadings; however the relative intensities changed significantly. In particular, a species with the (neutral molecule) formula C(17)H(26)O(8) increased substantially in intensity relative to other products as the mass loading decreased. Tandem mass spectrometry (MS(n)) of this species showed it to be a dimer of C(9)H(14)O(4) and C(8)H(12)O(4), most likely pinic acid and terpenylic acid, respectively. LCMS analysis showed different elution times for the dimer and monomer species, confirming that the dimer was not an artifact of ESI analysis. The particle number concentration increased linearly with ozone concentration (the limiting reactant in the experiment), arguing against gas phase dimerization as the rate limiting step in particle formation.

12 versus 24 h bed rest after acute ischemic stroke thrombolysis: a preliminary experience.

BACKGROUND: The practice of ≥24 h of bed rest after acute ischemic stroke thrombolysis is common among hospitals, but its value compared to shorter periods of bed rest is unknown. METHODS: Consecutive adult patients with a diagnosis of ischemic stroke who had received intravenous thrombolysis treatment from 1/1/2010 until 4/13/2016, identified from the local ischemic stroke registry, were included. Standard practice bed rest for ≥24 h, the protocol prior to 1/27/2014, was retrospectively compared with standard practice bed rest for ≥12 h, the protocol after that date. The primary outcome was favorable discharge location (defined as home, home with services, or acute rehabilitation). Secondary outcome measures included incidence of pneumonia, NIHSS at discharge, and length of stay. RESULTS: 392 patients were identified (203 in the ≥24 h group, 189 in the ≥12 h group). There was no significant difference in favorable discharge outcome in the ≥24 h bed rest protocol compared with the ≥12 h bed rest protocol in multivariable logistic regression analysis (76.2% vs. 70.9%, adjusted OR 1.20 CI 0.71-2.03). Compared with the ≥24 h bed rest group, pneumonia rates (8.3% versus 1.6%, adjusted OR 0.12 CI 0.03-0.55), median discharge NIHSS (3 versus 2, adjusted p = .034), and mean length of stay (5.4 versus 3.5 days, adjusted p = .006) were lower in the ≥12 h bed rest group. CONCLUSION: Compared with ≥24 h bed rest, ≥12 h bed rest after acute ischemic stroke reperfusion therapy appeared to be similar. A non-inferiority randomized trial is needed to verify these findings.

"Don't lose hope early": Hemorrhagic diffuse axonal injury on head computed tomography is not associated with poor outcome in moderate to severe traumatic brain injury patients.

BACKGROUND: Diffuse axonal injury (DAI) on magnetic resonance imaging has been associated with poor functional outcome after moderate-severe traumatic brain injury (msTBI). Yet, DAI assessment with highly sensitive magnetic resonance imaging techniques is unfeasible in the acute trauma setting, and computed tomography (CT) remains the key diagnostic modality despite its lower sensitivity. We sought to determine whether CT-defined hemorrhagic DAI (hDAI) is associated with discharge and favorable 3- and 12-month functional outcome (Glasgow Coma Scale score ≥4) after msTBI. METHODS: We analyzed 361 msTBI patients from the single-center longitudinal Outcome Prognostication in Traumatic Brain Injury study collected over 6 years (November 2009 to November 2015) with prospective outcome assessments at 3 months and 12 months. Patients with microhemorrhages on CT were designated "CT-hDAI-positive" and those without as "CT-hDAI-negative." For secondary analyses "CT-hDAI-positive" was stratified into two phenotypes according to presence ("associated") versus absence ("predominant") of concomitant large acute traumatic lesions to determine whether presence versus absence of additional focal mass lesions portends a different prognosis. RESULTS: Seventy (19%) patients were CT-hDAI-positive (n = 36 predominant; n = 34 associated hDAI). In univariate analyses, CT-hDAI-positive status was associated with discharge survival (p = 0.004) and favorable outcome at 3 months (p = 0.003) and 12 months (p = 0.005). After multivariable adjustment, CT-hDAI positivity was no longer associated with discharge survival and functional outcome (all ps > 0.05). Stratified by hDAI phenotype, predominant hDAI patients had worse trauma severity, longer intensive care unit stays, and more systemic medical complications. Predominant hDAI, but not associated hDAI, was an independent predictor of discharge survival (adjusted odds ratio, 24.7; 95% confidence interval [CI], 3.2-192.6; p = 0.002) and favorable 12-month outcome (adjusted odds ratio, 4.7; 95% CI, 1.5-15.2; p = 0.01). Sensitivity analyses using Cox regression confirmed this finding for 1-year survival (adjusted hazard ratio, 5.6; 95% CI, 1.3-23; p = 0.048). CONCLUSION: The CT-defined hDAI was not an independent predictor of unfavorable short- and long-term outcomes and should not be used for acute prognostication in msTBI patients. Predominant hDAI patients had good clinical outcomes when supported to intensive care unit discharge and beyond. LEVEL OF EVIDENCE: Prognostic study, level III.

The Estimated Verbal GCS Subscore in Intubated Traumatic Brain Injury Patients: Is it Really Better?

The Glasgow Coma Scale (GCS) has limited utility in intubated patients due to the inability to assign verbal subscores. The verbal subscore can be derived from the eye and motor subscores using a mathematical model, but the advantage of this method and its use in outcome prognostication in traumatic brain injury (TBI) patients remains unknown. We compared the validated "Core+CT"-IMPACT-model performance in 251 intubated TBI patients prospectively enrolled in the longitudinal OPTIMISM study between November 2009 and May 2015 when substituting the original motor GCS (mGCS) with the total estimated GCS (teGCS; with estimated verbal subscore). We hypothesized that model performance would improve with teGCS. Glasgow Outcome Scale (GOS) scores were assessed at 3 and 12 months by trained interviewers. In the complete case analysis, there was no statistically or clinically significant difference in the discrimination (C-statistic) at either time-point using the mGCS versus the teGCS (3 months: 0.893 vs. 0.871;12 months: 0.926 vs. 0.92). At 3 months, IMPACT-model calibration was excellent with mGCS and teGCS (Hosmer-Lemeshow "goodness-of-fit" chi square p value 0.9293 and 0.9934, respectively); it was adequate at 12 months with teGCS (0.5893) but low with mGCS (0.0158), possibly related to diminished power at 12 months. At both time-points, motor GCS contributed more to the variability of outcome (Nagelkerke ΔR2) than teGCS (3 months: 5.8% vs. 0.4%; 12 months: 5% vs. 2.6%). The sensitivity analysis with imputed missing outcomes yielded similar results, with improved calibration for both GCS variants. In our cohort of intubated TBI patients, there was no statistically or clinically meaningful improvement in the IMPACT-model performance by substituting the original mGCS with teGCS.

Activated carbons from end-products of tree nut and tree fruit production as sorbents for removing methyl bromide in ventilation effluent following postharvest chamber fumigation.

End-products of tree nuts and tree fruits grown in California, USA were evaluated for the ability to remove methyl bromide (MB) from ventilation effluent following postharvest chamber fumigation. Activated carbon sorbents from walnut and almond shells as well as peach and prune pits were prepared using different methods of pyrolysis, activation, and quenching. Each source and preparation was evaluated for yield from starting material (%, m/m) and performance on tests where MB-containing airstreams were directed through a columnar bed of the activated carbon in an experimental apparatus, termed a parallel adsorbent column tester, which was constructed as a scaled-down model of a chamber ventilation system. We report the number of doses needed to first observe the breakthrough of MB downstream of the bed and the capacity of the activated carbon for MB (%, m/m) based on a fractional percentage of MB mass sorbed at breakthrough relative to mass of the bed prior to testing. Results were based on a novel application of solid-phase microextraction with time-weighted averaging sampling of MB concentration in airstreams, which was quantitative across the range of fumigation-relevant conditions and statistically unaffected by relative humidity. Activated carbons from prune pits, prepared either by steam activation or carbon dioxide activation coupled to water quenching, received the greatest number of doses prior to breakthrough and had the highest capacity, approximately 12-14%, outperforming a commercially marketed activated carbon derived from coconut shells. Experimental evidence is presented that links discrepancy in performance to the relative potential for activated carbons to preferentially sorb water vapor relative to MB.

Oligomer formation pathways in secondary organic aerosol from MS and MS/MS measurements with high mass accuracy and resolving power.

Secondary organic aerosol (SOA) is formed when organic molecules react with oxidants in the gas phase to form particulate matter. Recent measurements have shown that more than half of the mass of laboratory-generated SOA consists of high molecular weight oligomeric compounds. In this work, the formation mechanisms of oligomers produced in the laboratory by ozonolysis of α-pinene, an important SOA precursor in ambient air, are studied by MS and MS/MS measurements with high accuracy and resolving power to characterize monomer building blocks and the reactions that couple them together. The distribution of oligomers in an SOA sample is complex, typically yielding over 1000 elemental formulas that can be assigned from an electrospray ionization mass spectrum. Despite this complexity, MS/MS spectra can be found that give strong evidence for specific oligomer formation pathways that have been postulated but not confirmed. These include aldol and gem-diol reactions of carbonyls as well as peroxyhemiacetal formation from hydroperoxides. The strongest evidence for carbonyl reactions is in the formation of hydrated products. Less compelling evidence is found for dehydrated products and secondary ozonide formation. The number of times that a monomer building block is observed as a fragmentation product in the MS/MS spectra is shown to be independent of the monomer vapor pressure, suggesting that oligomer formation is not driven by equilibrium partitioning of a monomer between the gas and particle phases, but rather by reactive uptake where a monomer collides with the particle surface and rapidly forms an oligomer.