iATPSnFR2: A high-dynamic-range fluorescent sensor for monitoring intracellular ATP.

We developed a significantly improved genetically encoded quantitative adenosine triphosphate (ATP) sensor to provide real-time dynamics of ATP levels in subcellular compartments. iATPSnFR2 is a variant of iATPSnFR1, a previously developed sensor that has circularly permuted superfolder green fluorescent protein (GFP) inserted between the ATP-binding helices of the ε-subunit of a bacterial F0-F1 ATPase. Optimizing the linkers joining the two domains resulted in a ~fivefold to sixfold improvement in the dynamic range compared to the previous-generation sensor, with excellent discrimination against other analytes, and affinity variants varying from 4 µM to 500 µM. A chimeric version of this sensor fused to either the HaloTag protein or a suitable spectrally separated fluorescent protein provides an optional ratiometric readout allowing comparisons of ATP across cellular regions. Subcellular targeting the sensor to nerve terminals reveals previously uncharacterized single-synapse metabolic signatures, while targeting to the mitochondrial matrix allowed direct quantitative probing of oxidative phosphorylation dynamics.

Optimized Red-Absorbing Dyes for Imaging and Sensing.

Rhodamine dyes are excellent scaffolds for developing a broad range of fluorescent probes. A key property of rhodamines is their equilibrium between a colorless lactone and fluorescent zwitterion. Tuning the lactone-zwitterion equilibrium constant (KL-Z) can optimize dye properties for specific biological applications. Here, we use known and novel organic chemistry to prepare a comprehensive collection of rhodamine dyes to elucidate the structure-activity relationships that govern KL-Z. We discovered that the auxochrome substituent strongly affects the lactone-zwitterion equilibrium, providing a roadmap for the rational design of improved rhodamine dyes. Electron-donating auxochromes, such as julolidine, work in tandem with fluorinated pendant phenyl rings to yield bright, red-shifted fluorophores for live-cell single-particle tracking (SPT) and multicolor imaging. The N-aryl auxochrome combined with fluorination yields red-shifted Förster resonance energy transfer (FRET) quencher dyes useful for creating a new semisynthetic indicator to sense cAMP using fluorescence lifetime imaging microscopy (FLIM). Together, this work expands the synthetic methods available for rhodamine synthesis, generates new reagents for advanced fluorescence imaging experiments, and describes structure-activity relationships that will guide the design of future probes.

A general method to optimize and functionalize red-shifted rhodamine dyes.

Expanding the palette of fluorescent dyes is vital to push the frontier of biological imaging. Although rhodamine dyes remain the premier type of small-molecule fluorophore owing to their bioavailability and brightness, variants excited with far-red or near-infrared light suffer from poor performance due to their propensity to adopt a lipophilic, nonfluorescent form. We report a framework for rationalizing rhodamine behavior in biological environments and a general chemical modification for rhodamines that optimizes long-wavelength variants and enables facile functionalization with different chemical groups. This strategy yields red-shifted 'Janelia Fluor' (JF) dyes useful for biological imaging experiments in cells and in vivo.

A Sulfur-Controlled Approach to the Synthesis of Linerixibat.

Establishing the two stereocenters in the benzothiazepine ring of linerixibat (GSK2330672) has been a long-standing problem at GSK. Our solution rests on an episulfonium-controlled Ritter reaction followed by a sulfoxide-directed reduction. A rationale for both steps is based on a mixture of literature precedent and computational experiments. Transition state modeling suggests the sulfoxide-directed reduction proceeds through electronic repulsion between the lone pair of electrons on sulfur and the incoming borohydride anion.

Understanding the role of COVID-19-related workplace stress and institutional betrayal on mental health in nurses: Some heroes wear scrubs.

This study examined the association of three specific COVID-19-related workplace stressors (percentage of nursing work with COVID-positive [COVID+] patients, number of COVID-19-related patient deaths witnessed, and living separately from family for safety) and their associations with posttraumatic stress symptoms (PTSS) and symptoms of major depressive disorder (MDD) and generalized anxiety disorder (GAD) among 391 nurses (93.6% White, 93.4% utilize she/her pronouns). Cross-sectional data were collected via an online survey. Institutional betrayal (i.e., the perception that an institution failed to protect a member who depends on and trusts it) was examined as a moderator of these associations. Although institutional betrayal was not a significant moderator in the three individual models, it held small-to-medium-sized positive main effects with PTSS and symptoms of GAD and MDD in both the individual and combined models. In the individual models, the percentage of nursing work with COVID+ patients was significantly positively associated with all three mental health conditions, f2 = .019-.195, whereas it only showed a significant effect with PTSS in the combined model, f2 = .138. Living separately from family was significantly positively associated with PTSS and MDD symptoms in both the individual, f2 = .037 and .015, respectively, and combined models, f2 = .025 and .013, respectively. Number of patient deaths held a significant positive association with PTSS alone, f2 = .022, in the individual model only. The findings are discussed in light of ways in which health care settings can better support and prioritize mental health among nursing staff.

Alcohol Use and Mental Health Symptoms in Nurses during the Early Months of COVID-19.

OBJECTIVE: The current study examined associations of symptoms of posttraumatic stress disorder [PTSD], depression, and generalized anxiety disorder [GAD] with alcohol consumption and drinking to cope in a sample of 310 nurses during the first six months of the COVID-19 pandemic. METHOD: Using a cross-sectional design, nurses completed online surveys. RESULTS: Over 50% of the sample reported alcohol misuse and 12.2% reported drinking to cope. Further, 38.7% reported elevated symptoms of PTSD, 29.7% moderate-to-high symptoms of depression, and 56.8% elevated symptoms of GAD symptoms. Hierarchical regression analyses were conducted to examine how mental health symptoms were associated with alcohol outcomes, controlling for age, gender pronouns, education, and race. No significant predictors emerged for alcohol consumption. Significant associations of symptoms of PTSD and depression were found for drinking to cope, such that higher levels of mental health symptoms were associated with greater endorsement of drinking to cope. CONCLUSION: Results are discussed in light of increasing prevention and support services for nurses.

Longitudinal associations of chronic health stress and COVID-19-related anxiety among outpatients with anxiety and mood disorders.

BACKGROUND: The 2019 coronavirus (COVID-19) pandemic led to elevated levels of psychological distress on a global scale. Given that individuals with pre-existing physical conditions are at risk for worse COVID-19 outcomes, those dealing with the stress of physical health problems (including knowing someone with health problems) may experience more severe distress during the pandemic. METHODS: Patients with emotional disorders who completed a diagnostic assessment in the 6 months prior to COVID-19 were surveyed in May-June 2020 on their emotional reactions to COVID-19 (N = 77). RESULTS: Multiple linear regression was used to test the hypothesis that chronic stress due to having and knowing others with physical health problems would predict COVID-related worries and behaviours, holding pre-COVID levels of depression, anxiety and worry about health constant. Chronic stress surrounding the health of others was significantly associated with experiencing more severe COVID-related worry and behaviours. In comparison, chronic stress due to one's own health problems had weak and non-significant associations with COVID-related worries and behaviours. CONCLUSIONS: Results indicate that outpatients who report stress about surrounding loved one's health are at risk for experiencing more severe distress during a health pandemic and thus, may benefit from targeted outreach, assessment and intervention.

Thermal and Catalytic Decomposition of 2-Hydroxyethylhydrazine and 2-Hydroxyethylhydrazinium Nitrate Ionic Liquid.

To develop chemical kinetics models for the combustion of ionic liquid-based monopropellants, identification of the elementary steps in the thermal and catalytic decomposition of components such as 2-hydroxyethylhydrazinium nitrate (HEHN) is needed but is currently not well understood. The first decomposition step in protic ionic liquids such as HEHN is typically the proton transfer from the cation to the anion, resulting in the formation of 2-hydroxyethylhydrazine (HEH) and HNO3. In the first part of this investigation, the high-temperature thermal decomposition of HEH is probed with flash pyrolysis (<1400 K) and vacuum ultraviolet (10.45 eV) photoionization time-of-flight mass spectrometry (VUV-PI-TOFMS). Next, the investigation into the thermal and catalytic decomposition of HEHN includes two mass spectrometric techniques: (1) tunable VUV-PI-TOFMS (7.4-15 eV) and (2) ambient ionization mass spectrometry utilizing both plasma and laser ionization techniques whereby HEHN is introduced onto a heated inert or iridium catalytic surface and the products are probed. The products can be identified by their masses, their ionization energies, and their collision-induced fragmentation patterns. Formation of product species indicates that catalytic surface recombination is an important reaction process in the decomposition mechanism of HEHN. The products and their possible elementary reaction mechanisms are discussed.

Developing and Validating Clinical Questionnaires.

Coinciding with the development and revision of conceptual models of psychopathology, there has been a proliferation in the number of self-report clinical questionnaires and studies evaluating their psychometric properties. Unfortunately, many clinical measures are constructed and evaluated using suboptimal methods. This review provides current guidelines for the conceptualization, development, and psychometric validation of clinical questionnaires using latent variable methods. A two-stage exploratory-confirmatory framework is provided. The exploratory stage includes item selection and revision, initial structural evaluation, and preliminary tests of concurrent validity (e.g., convergent and discriminant). The confirmatory stage involves replicating factor structure using a more restrictive model, identifying areas of model strain, conducting additional tests of concurrent and predictive validity, and evaluating measurement invariance. Recommendations are provided for (a) item generation, (b) how to use different types of exploratory and confirmatory factor models to determine structure, and (c) evaluating reliability and validity using a latent variable measurement model approach.

A general method to fine-tune fluorophores for live-cell and in vivo imaging.

Pushing the frontier of fluorescence microscopy requires the design of enhanced fluorophores with finely tuned properties. We recently discovered that incorporation of four-membered azetidine rings into classic fluorophore structures elicits substantial increases in brightness and photostability, resulting in the Janelia Fluor (JF) series of dyes. We refined and extended this strategy, finding that incorporation of 3-substituted azetidine groups allows rational tuning of the spectral and chemical properties of rhodamine dyes with unprecedented precision. This strategy allowed us to establish principles for fine-tuning the properties of fluorophores and to develop a palette of new fluorescent and fluorogenic labels with excitation ranging from blue to the far-red. Our results demonstrate the versatility of these new dyes in cells, tissues and animals.

High-density three-dimensional localization microscopy across large volumes.

Extending three-dimensional (3D) single-molecule localization microscopy away from the coverslip and into thicker specimens will greatly broaden its biological utility. However, because of the limitations of both conventional imaging modalities and conventional labeling techniques, it is a challenge to localize molecules in three dimensions with high precision in such samples while simultaneously achieving the labeling densities required for high resolution of densely crowded structures. Here we combined lattice light-sheet microscopy with newly developed, freely diffusing, cell-permeable chemical probes with targeted affinity for DNA, intracellular membranes or the plasma membrane. We used this combination to perform high-localization precision, ultrahigh-labeling density, multicolor localization microscopy in samples up to 20 µm thick, including dividing cells and the neuromast organ of a zebrafish embryo. We also demonstrate super-resolution correlative imaging with protein-specific photoactivable fluorophores, providing a mutually compatible, single-platform alternative to correlative light-electron microscopy over large volumes.

Bright photoactivatable fluorophores for single-molecule imaging.

Small-molecule fluorophores are important tools for advanced imaging experiments. We previously reported a general method to improve small, cell-permeable fluorophores which resulted in the azetidine-containing 'Janelia Fluor' (JF) dyes. Here, we refine and extend the utility of these dyes by synthesizing photoactivatable derivatives that are compatible with live-cell labeling strategies. Once activated, these derived compounds retain the superior brightness and photostability of the JF dyes, enabling improved single-particle tracking and facile localization microscopy experiments.

Evaluating dimensional models of psychopathology in outpatients diagnosed with emotional disorders: A cautionary tale.

BACKGROUND: Mental disorders cluster together systematically. Through factor analysis of disorder comorbidity, investigators are establishing the latent dimensions that underlie the development of related syndromes. However, these dimensions have not been validated across diverse patient samples, in which comorbidity patterns vary widely. METHOD: We assessed 4,928 outpatients seeking treatment for emotional disorders with a semistructured diagnostic interview. This was the largest patient sample as yet for an evaluation of the latent structure of mental disorders. We compared several competing dimensional models of common mental disorders via confirmatory factor analysis. RESULTS: The hypothesized confirmatory factor model-anchored by internalizing and externalizing spectra-fit the diagnostic data poorly. Neither a one-factor model, reflecting a unitary liability to all mental disorders, nor a three-factor model, wherein the internalizing dimension bifurcated into distress and fear subfactors, fit appreciably better. CONCLUSIONS: These data provide novel evidence that the internalizing and externalizing spectra are not structurally sound in all clinical contexts. We speculate about the causes of model misfit and advise additional research into the generalizability-with respect to sample, input data, developmental stage, and more-of dimensional models of mental disorder.

Movement and structure of mitochondria in oligodendrocytes and their myelin sheaths.

Mitochondria play several crucial roles in the life of oligodendrocytes. During development of the myelin sheath they are essential providers of carbon skeletons and energy for lipid synthesis. During normal brain function their consumption of pyruvate will be a key determinant of how much lactate is available for oligodendrocytes to export to power axonal function. Finally, during calcium-overload induced pathology, as occurs in ischemia, mitochondria may buffer calcium or induce apoptosis. Despite their important functions, very little is known of the properties of oligodendrocyte mitochondria, and mitochondria have never been observed in the myelin sheaths. We have now used targeted expression of fluorescent mitochondrial markers to characterize the location and movement of mitochondria within oligodendrocytes. We show for the first time that mitochondria are able to enter and move within the myelin sheath. Within the myelin sheath the highest number of mitochondria was in the cytoplasmic ridges along the sheath. Mitochondria moved more slowly than in neurons and, in contrast to their behavior in neurons and astrocytes, their movement was increased rather than inhibited by glutamate activating NMDA receptors. By electron microscopy we show that myelin sheath mitochondria have a low surface area of cristae, which suggests a low ATP production. These data specify fundamental properties of the oxidative phosphorylation system in oligodendrocytes, the glial cells that enhance cognition by speeding action potential propagation and provide metabolic support to axons.

Direct Copper(III) Formation from O2 and Copper(I) with Histamine Ligation.

Histamine chelation of copper(I) by a terminal histidine residue in copper hydroxylating enzymes activates dioxygen to form unknown oxidants, generally assumed as copper(II) species. The direct formation of copper(III)-containing products from the oxygenation of histamine-ligated copper(I) complexes is demonstrated here, indicating that copper(III) is a viable oxidation state in such products from both kinetic and thermodynamic perspectives. At low temperatures, both trinuclear Cu(II)2Cu(III)O2 and dinuclear Cu(III)2O2 predominate, with the distribution dependent on the histamine ligand structure and oxygenation conditions. Kinetics studies suggest the bifurcation point to these two products is an unobserved peroxide-level dimer intermediate. The hydrogen atom reactivity difference between the trinuclear and binuclear complexes at parity of histamine ligand is striking. This behavior is best attributed to the accessibility of the bridging oxide ligands to exogenous substrates rather than a difference in oxidizing abilities of the clusters.

Virginia Orange: A Versatile, Red-Shifted Fluorescein Scaffold for Single- and Dual-Input Fluorogenic Probes.

Fluorogenic molecules are important tools for biological and biochemical research. The majority of fluorogenic compounds have a simple input-output relationship, where a single chemical input yields a fluorescent output. Development of new systems where multiple inputs converge to yield an optical signal could refine and extend fluorogenic compounds by allowing greater spatiotemporal control over the fluorescent signal. Here, we introduce a new red-shifted fluorescein derivative, Virginia Orange, as an exceptional scaffold for single- and dual-input fluorogenic molecules. Unlike fluorescein, installation of a single masking group on Virginia Orange is sufficient to fully suppress fluorescence, allowing preparation of fluorogenic enzyme substrates with rapid, single-hit kinetics. Virginia Orange can also be masked with two independent moieties; both of these masking groups must be removed to induce fluorescence. This allows facile construction of multi-input fluorogenic probes for sophisticated sensing regimes and genetic targeting of latent fluorophores to specific cellular populations.

Identification of fleeting electrochemical reaction intermediates using desorption electrospray ionization mass spectrometry.

We report a new method for the mass spectrometric detection of fleeting reaction intermediates in electrochemical reactions utilizing a "waterwheel" working electrode setup. This setup takes inspiration from desorption electrospray ionization (DESI) mass spectrometry, where the sampling time is on the order of milliseconds, to sample directly from the surface of a working electrode for mass spectrometric analysis. We present data that show the formation of a diimine intermediate of the electrochemical oxidation of uric acid that has a lifetime in solution of 23 ms as well as data that provide evidence for the formation of a similar diimine species from the electrooxidation of xanthine, which has not been previously observed.

Detection of the short-lived radical cation intermediate in the electrooxidation of N,N-dimethylaniline by mass spectrometry.

The N,N-dimethylaniline (DMA) radical cation DMA(.+) , a long-sought transient intermediate, was detected by mass spectrometry (MS) during the electrochemical oxidation of DMA. This was accomplished by coupling desorption electrospray ionization (DESI) MS with a waterwheel working electrode setup to sample the surface of the working electrode during electrochemical analysis. This study clearly shows that DESI-based electrochemical MS is capable of capturing electrochemically generated intermediates with half-lives on the order of microseconds, which is 4-5 orders of magnitude faster than previously reported electrochemical mass spectrometry techniques.

Depressive symptoms and the incidence of adult-onset asthma in African American women.

BACKGROUND: Some evidence suggests that depression may increase the risk of adult-onset asthma. No data are available for African American women, in whom the prevalence of depression and asthma is high. OBJECTIVE: To conduct prospective analyses of the relation of depressive symptoms to asthma incidence in the Black Women's Health Study, a prospective cohort of US black women followed since 1995 with mailed biennial questionnaires. METHODS: Of 31,848 participants followed from 1999 to 2011, 771 reported incident asthma. Depressive symptoms were ascertained on 1999 and 2005 follow-up questionnaires with the Center for Epidemiological Studies-Depression Scale (CES-D). Participants rated the frequency of 20 symptoms. A score was calculated by summing the responses to all questions. Cox regression models were used to derive incidence rate ratios and 95% confidence intervals for 4 categories of the CES-D score in relation to incident asthma, adjusted for body mass index, smoking, and other covariates. RESULTS: The multivariable incidence rate ratio in the highest category of CES-D score (≥ 33) compared with the lowest (<16) was 2.08 (95% confidence interval 1.58-2.74), with a significant trend (P < .0001). The incidence rate ratio was higher in women who took antidepressants, were current or former smokers, were not obese, and were at least 40 years old, although there were no statistically significant interactions. CONCLUSION: A positive association was observed between CES-D score and the incidence of adult-onset asthma. If the hypothesis is confirmed, depression could contribute substantially to the burden of asthma in adults.

Abuse during childhood and adolescence and risk of adult-onset asthma in African American women.

BACKGROUND: Experiences of violence contribute to the occurrence of childhood asthma, but there is little information on the effect of early-life abuse on adult-onset asthma. OBJECTIVE: We prospectively assessed the relation between physical and sexual abuse during childhood and adolescence and the incidence of adult-onset asthma in the Black Women's Health Study. METHODS: We followed 28,456 women from 1995 through 2011 with biennial mailed questionnaires. Experiences of physical and sexual abuse that occurred during childhood and adolescence were obtained in 2005. Cox regression models were used to estimate incidence rate ratios (IRRs) and 95% CIs. RESULTS: During 417,931 person-years of follow-up, 1,160 participants reported physician-diagnosed asthma and concurrent use of asthma medication. Compared with women who experienced no abuse during childhood or adolescence, the multivariable IRR for any childhood abuse was 1.24 (95% CI, 1.06-1.45), and for any adolescent abuse, it was 1.10 (95% CI, 0.88-1.36). The IRR was higher for childhood physical abuse (IRR, 1.29; 95% CI, 1.07-1.49) than for childhood sexual abuse (IRR, 1.15; 95% CI, 0.88-1.49). IRRs for physical and sexual abuse during adolescence were compatible with 1.0. The association between childhood abuse and asthma incidence was stronger in older compared with younger women. CONCLUSION: In this large cohort of African American women, there was a positive association between adult-onset asthma and childhood physical abuse and weaker associations for childhood sexual abuse and any abuse during adolescence. Given the high prevalence of asthma and childhood abuse, this association is of public health importance.