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Charge reduction reactions are important for native mass spectrometry (nMS) because lower charge states help retain native-like conformations and preserve noncovalent interactions of protein complexes. While mechanisms of charge reduction reactions are not well understood, they are generally achieved through the addition of small molecules, such as polyamines, to traditional nMS buffers. Here, we present new evidence that surface-active, charge reducing reagents carry away excess charge from the droplet after being emitted due to Coulombic repulsion, thereby reducing the overall charge of the droplet. Furthermore, these processes are directly linked to two mechanisms for electrospray ionization, specifically the charge residue and ion evaporation models (CRM and IEM). Selected protein complexes were analyzed in solutions containing ammonium acetate and selected trialkylamines or diaminoalkanes of increasing alkyl chain lengths. Results show that amines with higher surface activity have increased propensities for promoting charge reduction of the protein ions. The electrospray ionization (ESI) emitter potential was also found to be a major contributing parameter to the prevalence of charge reduction; higher emitter potentials consistently coincided with lower average charge states among all protein complexes analyzed. These results offer experimental evidence for the mechanism of charge reduction in ESI and also provide insight into the final stages of the ESI and their impact on biological ions.

Here, we describe a digital-waveform dual-quadrupole mass spectrometer that enhances the performance of our drift tube FT-IMS high-resolution Orbitrap mass spectrometer (MS). The dual-quadrupole analyzer enhances the instrument capabilities for studies of large protein and protein complexes. The first quadrupole (q) provides a means for performing low-energy collisional activation of ions to reduce or eliminate noncovalent adducts, viz., salts, buffers, detergents, and/or endogenous ligands. The second quadrupole (Q) is used to mass-select ions of interest for further interrogation by ion mobility spectrometry and/or collision-induced dissociation (CID). Q is operated using digital-waveform technology (DWT) to improve the mass selection compared to that achieved using traditional sinusoidal waveforms at floated DC potentials (>500 V DC). DWT allows for increased precision of the waveform for a fraction of the cost of conventional RF drivers and with readily programmable operation and precision (Hoffman, N. M. . A comparison-based digital-waveform generator for high-resolution duty cycle. Review of Scientific Instruments 2018, 89, 084101).

Objectives: To provide ultrasound baselines for spleen length in homozygous sickle cell disease (HbSS) and in normal controls with a HbAA genotype. Methods: The Jamaican cohort study identified 311 babies with HbSS and 246 matched HbAA controls during the screening of 100,000 consecutive deliveries in Kingston, Jamaica from 1973 to 1981. Ultrasonography commenced in 1988 when the youngest patients were aged 6 years at which time deaths, emigrations and default had reduced the numbers to 206 HbSS and 89 controls. It continued annually until 2000. Results: The spleen was visualized in all HbAA controls but in only 1103/2138 (52%) scans in HbSS. Where available, mean splenic lengths were significantly lower in HbSS (77–103 mm in males, 70–83 mm in females) compared to normal controls (89–101 mm in males, 86–95 mm in females). Assessed by statistical modelling after adjusting for body height, the splenic ratio (splenic length/body height) declined over the age range 12–20 years in HbSS, consistent with progressive splenic fibrosis. Genetic factors known to inhibit sickling, α thalassemia and fetal hemoglobin level (HbF) significantly reduced the decline in splenic ratio. Clinical splenomegaly was an insensitive measure of splenic enlargement as only 50% of patients aged 18 years and above with spleens measuring ≥150 mm on ultrasonography had palpable spleens. Conclusions: An age-related decline in splenic length occurred in HbSS and occurred more slowly with genetic factors known to inhibit sickling. The standards provided may be of value in assessing minor degrees of subclinical acute splenic sequestration. Advances in knowledge These are the first standards available for splenic length in HbSS. They may be useful in detecting red cell sequestration, not apparent from clinical splenomegaly and also provide a model for identifying factors inhibiting vaso-occlusion.

PurposeThis study aims to examine the determinants of corporate green investments (GI) by using a series of both firm- and country-level factors.Design/methodology/approachThe authors collect information on environmental expenditures of 763 firms from 40 countries and use random effects regressions to identify the determinants of GI.FindingsThe authors find that larger firms tend to invest more in green projects, whereas firms that are highly valued or more profitable are less likely to go green. In terms of country-level determinants, we find that the gross domestic product (GDP) per capita and population are positively related with GI, while GDP growth and surface area are negatively associated with GI. Additionally, firms in common-law countries and English-speaking countries make fewer GI than firms in other countries.Social implicationsThe findings of this research not only contribute to the academic literature in these areas, but also have important implications for both regulators and policymakers in countries that exhibit sub-par GI or who otherwise aim to increase GI by firms operating in their country.Originality/valueThe authors identify and explore the key determinants of GI from both a firm- and country-level perspective.

Stabilities and structure(s) of proteins are directly coupled to their local environment or Gibbs free energy landscape as defined by solvent, temperature, pressure, and concentration. Solution pH, ionic strength, cofactors, chemical chaperones, and osmolytes perturb the chemical potential and induce further changes in structure, stability, and function. At present, no single analytical technique can monitor these effects in a single measurement. Mass spectrometry and ion mobility-mass spectrometry play increasingly essential roles in studies of proteins, protein complexes, and even membrane protein complexes; however, with few exceptions, the effects of the solution temperature on the stability and structure(s) of analytes have not been thoroughly investigated. Here, we describe a new variable-temperature electrospray ionization (vT-ESI) source that utilizes a thermoelectric chip to cool and heat the solution contained within the static ESI emitter. This design allows for solution temperatures to be varied from ~5 to 98 °C with short equilibration times (

Rotationally averaged collision cross section (CCS) values for a series of proteins and protein complexes ranging in size from 8.6 to 810 kDa are reported. The CCSs were obtained using a native electrospray ionization drift tube ion mobility-Orbitrap mass spectrometer specifically designed to enhance sensitivity while having high-resolution ion mobility and mass capabilities. Periodic focusing (PF)-drift tube (DT)-ion mobility (IM) provides first-principles determination of the CCS of large biomolecules that can then be used as CCS calibrants. The experimental, first-principles CCS values are compared to previously reported experimentally determined and computationally calculated CCS using projected superposition approximation (PSA), the Ion Mobility Projection Approximation Calculation Tool (IMPACT), and Collidoscope. Experimental CCS values are generally in agreement with previously reported CCSs, with values falling within ~5.5%. In addition, an ion mobility resolution (CCS centroid divided by CCS fwhm) of ~60 is obtained for pyruvate kinase (MW ~ 233 kDa); however, ion mobility resolution for bovine serum albumin (MW ~ 68 kDa) is less than ~20, which arises from sample impurities and underscores the importance of sample quality. The high resolution afforded by the ion mobility-Orbitrap mass analyzer provides new opportunities to understand the intricate details of protein complexes such as the impact of post-translational modifications (PTMs), stoichiometry, and conformational changes induced by ligand binding.

In radially staged lean direct injection (LDI) systems, pilot fuel plays an important role in cooling the mains fuel gallery in regions of the flight envelope where the mains fuel is stagnant. Under these conditions, managing wetted wall temperatures is vital to avoid the formation of carbonaceous particles, which become deposited on the surfaces of the fuel gallery and can lead to a deterioration in system performance. The prediction of wetted wall temperatures therefore represents an important aspect of the injector design phase. Such predictions are often based on injector thermal models, which tend to rely on the application of convective boundary conditions from empirical heat transfer correlations. The use of these correlations leads to questions over the accuracy of predicted wetted wall temperatures and therefore uncertainty over the probability of deposition. This paper seeks to improve on the current situation by applying the inverse conduction technique to determine heat transfer coefficients (HTCs) specific to the pilot fuel gallery. These HTCs are crucial for determining wetted wall temperatures in the pilot and mains fuel galleries and principally govern the risk of deposition in the stagnant mains. The pilot heat transfer data are further examined alongside measurements of the pilot residence time distribution, which together control the risk of pilot deposition at low fuel flow rates. Both the heat transfer and residence time measurements demonstrate the opportunity for future fuel gallery design refinement and provide the supporting data to facilitate this.

Understanding the molecular driving forces that underlie membrane protein-lipid interactions requires the characterization of their binding thermodynamics. Here, we employ native mass spectrometry in conjunction with a variable temperature apparatus to determine the thermodynamics of individual lipid binding events to the human G-protein-gated inward rectifier potassium channel, Kir3.2. We find that Kir3.2 displays distinct thermodynamic strategies to engage phosphatidylinositol (PI) and phosphorylated forms thereof. The addition of a 4’- phosphate to PI with 18:1-18:1 (DO) tails results in an increase in favorable entropy along with an enthalpic penalty. The binding of PI with two or more phosphates is more complex where lipids bind to Kir3.2 with the cytoplasmic domain in either a docked or extended configuration. Remarkably, the interaction of 4,5-bisphosphate DOPI (DOPI(4,5)P2) with Kir3.2 is solely driven by a large, favorable change in entropy. Installment of a third 3’-phosphate to DOPI(4,5)P2 results in an alternative thermodynamic strategy for the first binding event whereas each successive binding event shows strong enthalpy-entropy compensation. PI(4,5)P2 with 18:0-20:4 tails results in an inversion of thermodynamic parameters where the change in enthalpy now dominates. Collectively, the data show that entropy can indeed play important roles in regulating membrane protein-lipid interactions.

Chaperonins are nanomachines that harness ATP hydrolysis to power and catalyze protein folding, chemical action that is directly linked to the maintenance of cell function through protein folding/refolding and assembly. GroEL and the GroEL-GroES complex are archetypal examples of such protein folding machines. Here, variable-temperature-electrospray ionization (vT-ESI) native mass spectrometry is used to delineate the effects of solution temperature and ATP concentrations on the stabilities of GroEL and GroEL/GroES complexes. The results show clear evidences for de-stabilization of both GroEL14 and GroES7 at temperatures of 50 oC and 45 oC, respectively, substantially below the pre-viously reported melting temperature (Tm ~ 70 oC). This destabilization is accompanied by temperature-dependent reaction products that have previously unreported stoichiometries, viz. GroEL14-GroESx-ATPy, where x = 1, 2, 8 and y = 0, 1, 2, that are also dependent on Mg2+ and ATP concentrations. Variable-temperature native mass spectrometry re-veals new insights about the stability of GroEL in response to several environmental effects: (i) temperature-dependent ATP binding to GroEL (ii) effects of temperature as well as Mg2+ and ATP concentrations on the stoichiome-try of the GroEL-GroES complex, with Mg2+ showing greater effects compared to ATP; and, (iii) a change in the temper-ature-dependent stoichiometries of the GroEL-GroES complex (GroEL14-GroES7 vs GroEL14-GroES8) between 24 to 56 oC. The similarities between results obtained using native MS and cryo-EM (Clare et al., An expanded protein folding cage in the GroEL-gp31 complex. J. Mol. Biol. 2006, 358, 905-11; Ranson et al., Allosteric signaling of ATP hydrolysis in GroEL–GroES complexes. Nat. Struct. Mol. Biol. 2006, 13, 147-152.) underscores the utility of native MS for investiga-tions of molecular machines as well as identification of key intermediates involved in the chaperone-assisted protein folding cycle.

Here, we describe a digital-waveform dual-quadrupole mass spectrometer that enhances the performance of our drift tube FT-IMS high-resolution Orbitrap mass spectrometer (MS). The dual-quadrupole analyzer enhances the instrument capabilities for studies of large protein and protein complexes. The first quadrupole (q) provides a means for performing low-energy collisional activation of ions to reduce or eliminate noncovalent adducts, viz., salts, buffers, detergents, and/or endogenous ligands. The second quadrupole (Q) is used to mass-select ions of interest for further interrogation by ion mobility spectrometry and/or collision-induced dissociation (CID). Q is operated using digital-waveform technology (DWT) to improve the mass selection compared to that achieved using traditional sinusoidal waveforms at floated DC potentials (>500 V DC). DWT allows for increased precision of the waveform for a fraction of the cost of conventional RF drivers and with readily programmable operation and precision (Hoffman, N. M. et al.. A comparison-based digital-waveform generator for high-resolution duty cycle.

The paper provides robust evidence that compliance with Basel Core Principles (BCPs) has a strong positive effect on the Z-score of conventional banks, albeit less pronounced on the Zscore of Islamic banks. Using a sample of banks operating in 19 developing countries, the results appear to be driven by capital ratios, a component of Z-score for the two types of banks. Even though smaller on Islamic banks, individual chapters of BCPs also suggest a positive effect on the stability of conventional banks. The findings support the effective role of BCP standards in improving bank stability, whose important implications led to the Islamic Financial Services Board (IFSB) publication of new recommendations in 2015 to bring BCP standards in line with the Core Principles for Islamic Finance Regulation (CPIFRs) standards. Our findings suggest that because Islamic banks are benchmarked closely to BCPs, the implementation of CPFIRs should also positively affect their stability.

Ningli Wang,1 Da-Wen Lu,2 Yingzi Pan,3 Yury Astakhov,4 Tatyana Iureva,5 Adeniyi Adewale,6 Thomas M Walker6 1Beijing Tongren Eye Center, Beijing, People’s Republic of China; 2Tri-Service General Hospital, Taipei, Taiwan; 3Peking University First Hospital, Beijing, People’s Republic of China; 4Pavlov First Saint Petersburg State Medical University, Saint Petersburg, Russia; 5Irkutsk Branch of the Academician S.N. Fyodorov Eye Microsurgery Federal State Institution, Irkutsk, Russia; 6Novartis Pharmaceuticals Corporation, Fort Worth, TX, USACorrespondence: Ningli WangBeijing Tongren Eye Center, No. 1 Dongjiaomin Str., Dongcheng District, Beijing 100041, People’s Republic of ChinaTel +861058265922Email wningli@vip.163.comObjective: To demonstrate that the intraocular pressure (IOP)-lowering efficacy of a twice-daily brinzolamide 10 mg/mL (BRINZ)/brimonidine 2 mg/mL (BRIM) fixed-dose combination (BBFC) was non-inferior to its individual components (BRINZ+BRIM) dosed concomitantly in patients with open-angle glaucoma (OAG) or ocular hypertension (OHT). Safety was also evaluated.Methods and Analysis: This was a Phase III, multicenter, observer-masked study in patients from China, Russia and Taiwan. Patients aged ≥ 18 years with a mean IOP ≥ 21 mmHg and ≤ 36 mmHg in the same eye after washout of other IOP-lowering medications were included. Eligible patients were randomized (1:1) to receive BBFC or BRIZ+BRIM eye drops twice daily for 3 months. The primary endpoint was the mean change in diurnal IOP (averaged over 09:00, +2 h, and +7 h) from baseline to Month 3. Adverse events (AEs) were recorded throughout the study.Results: The per-protocol set included 349 patients (BBFC, n=172; BRINZ+BRIM, n=177). The mean±standard deviation diurnal IOP at baseline was 24.6± 2.66 mmHg in both groups. At Month 3, the least square mean±standard error change in diurnal IOP from baseline was − 7.2± 0.34 mmHg and − 7.3± 0.34 mmHg with BBFC and BRINZ+BRIM, respectively (between-group difference: 0.1 mmHg [95% CI − 0.5, 0.7]). In the BBFC and BRINZ+BRIM groups, 53.3% and 55.0% of patients achieved a diurnal IOP < 18 mmHg, and 43.2% and 37.4% of patients, respectively, achieved a mean diurnal IOP reduction > 30% from baseline at Month 3. Ocular AEs were reported in 28.7% (BBFC) and 22.5% (BRINZ+BRIM) of patients; conjunctival hyperemia was the most frequent ocular AE (BBFC, 6.4%; BRINZ+BRIM, 6.8%). Non-ocular AEs were reported in 32.4% (BBFC) and 30.4% (BRINZ+BRIM) of patients.Conclusion: The study findings demonstrate that the efficacy of twice-daily BBFC was non-inferior to BRINZ+BRIM in patients with OAG/OHT. The safety profile of BBFC was similar to that of BRINZ+BRIM.Keywords: brinzolamide/brimonidine fixed-dose combination, intraocular pressure reduction, ocular hypertension, open-angle glaucoma

Studies of large proteins, protein complexes, and membrane protein complexes pose new challenges, most notably the need for increased ion mobility (IM) and mass spectrometry (MS) resolution. This review covers evolutionary developments in IM-MS in the authors' and key collaborators' laboratories with specific focus on developments that enhance the utility of IM-MS for structural analysis. IM-MS measurements are performed on gas phase ions, thus "structural IM-MS" appears paradoxical-do gas phase ions retain their solution phase structure? There is growing evidence to support the notion that solution phase structure(s) can be retained by the gas phase ions. It should not go unnoticed that we use "structures" in this statement because an important feature of IM-MS is the ability to deal with conformationally heterogeneous systems, thus providing a direct measure of conformational entropy. The extension of this work to large proteins and protein complexes has motivated our development of Fourier-transform IM-MS instruments, a strategy first described by Hill and coworkers in 1985 (Anal Chem, 1985, 57, pp. 402-406) that has proved to be a game-changer in our quest to merge drift tube (DT) and ion mobility and the high mass resolution orbitrap MS instruments. DT-IMS is the only method that allows first-principles determinations of rotationally averaged collision cross sections (CSS), which is essential for studies of biomolecules where the conformational diversities of the molecule precludes the use of CCS calibration approaches. The Fourier transform-IM-orbitrap instrument described here also incorporates the full suite of native MS/IM-MS capabilities that are currently employed in the most advanced native MS/IM-MS instruments. © 2020 John Wiley & Sons Ltd. Mass Spec Rev.

Objective To compare the safety and efficacy of manual and powered irrigation of the middle ear using saline or 1% baby shampoo to treat biofilm-forming bacterial middle ear infections. Background Biofilms play a major role in recalcitrant otitis media and are challenging to treat. Many therapeutic strategies have been attempted and the role of topical therapies is still being investigated. Topical irrigation using saline or 1% baby shampoo and the use of a hydrodebrider have been investigated in biofilms involved in chronic rhinosinusitis and their role within the middle ear is yet to be determined. Methods Twenty-two adult chinchillas underwent bilateral trans-bullar inoculation of non-typable biofilm forming Haemophilus influenza followed by unilateral middle ear irrigation 5 days later using saline administered via a powered hydrodebrider or manual irrigation of saline or 1% baby shampoo. Contralateral inoculated ears served as control and were not irrigated. Two days following irrigation, the bullae were harvested and processed for scanning electron microscopy to assess biofilm surface area. Auditory brainstem responses were performed before bacterial inoculation and prior to euthanasia. Results Manual and powered irrigation were effective in reducing the surface area of biofilm when compared to the control group. The hydrodebrider demonstrated to be more effective at eradicating biofilm than manual irrigation, especially in areas of difficult access, such as the ventral portion of the chinchillas' bullae. There was no difference in manual irrigation of saline when compared to 1% baby shampoo. Irrigations either manually or using the hydrodebrider did not affect hearing, the vestibular system or facial function. Conclusion Middle ear biofilms can be treated safely and effectively with rinses using either normal saline or 1% baby shampoo administered manually or with a powered hydrodebrider. Level of evidence NA.