Chronic idiopathic constipation (CIC) and irritable bowel syndrome with constipation (IBS-C) are associated with significant social and economic burdens. To address these burdens, a deeper ...understanding of their root causes is required. A discrepancy exists between patients' and healthcare providers' (HCPs) perceptions of constipation symptoms and the impact of symptoms associated with CIC and IBS-C. Compared with the HCPs' perceptions of patients' symptoms, a greater percentage of patients report acceptance and feeling in control of their CIC or IBS-C symptoms. Unfortunately, only one-third of individuals with CIC or IBS-C formally consult an HCP about their constipation. Fewer than half take medications, and these are generally over-the-counter therapies rather than prescription therapies. For those who seek help, only one-fifth feel that their constipation symptoms are well managed. Notable sex and cultural differences exist regarding individuals consulting their HCP about constipation. Many individuals with CIC and IBS-C remain inadequately managed and unduly affected, contributing to the high social and economic burden of these conditions.
Highly reflective crystals of the nucleotide base guanine are widely distributed in animal coloration and visual systems. Organisms precisely control the morphology and organization of the crystals ...to optimize different optical effects, but little is known about how this is achieved. Here we examine a fundamental question that has remained unanswered after over 100 years of research on guanine: what are the crystals made of? Using solution-state and solid-state chemical techniques coupled with structural analysis by powder XRD and solid-state NMR, we compare the purine compositions and the structures of seven biogenic guanine crystals with different crystal morphologies, testing the hypothesis that intracrystalline dopants influence the crystal shape. We find that biogenic “guanine” crystals are not pure crystals but molecular alloys (aka solid solutions and mixed crystals) of guanine, hypoxanthine, and sometimes xanthine. Guanine host crystals occlude homogeneous mixtures of other purines, sometimes in remarkably large amounts (up to 20% of hypoxanthine), without significantly altering the crystal structure of the guanine host. We find no correlation between the biogenic crystal morphology and dopant content and conclude that dopants do not dictate the crystal morphology of the guanine host. The ability of guanine crystals to host other molecules enables animals to build physiologically “cheaper” crystals from mixtures of metabolically available purines, without impeding optical functionality. The exceptional levels of doping in biogenic guanine offer inspiration for the design of mixed molecular crystals that incorporate multiple functionalities in a single material.
Introduction
Synaptic loss is a robust and consistent pathology in Alzheimer's disease (AD) and the major structural correlate of cognitive impairment. Positron emission tomography (PET) imaging of ...synaptic vesicle glycoprotein 2A (SV2A) has emerged as a promising biomarker of synaptic density.
Methods
We measured SV2A binding in 34 participants with early AD and 19 cognitively normal (CN) participants using 11CUCB‐J PET and a cerebellar reference region for calculation of the distribution volume ratio.
Results
We observed widespread reductions of SV2A binding in medial temporal and neocortical brain regions in early AD compared to CN participants. These reductions were largely maintained after correction for volume loss and were more extensive than decreases in gray matter volume.
Conclusion
We were able to measure widespread synaptic loss due to AD using 11CUCB‐J PET. Future studies will continue to evaluate the utility of SV2A PET for tracking AD progression and for monitoring potential therapies.
Nitric oxide (NO) has earned the reputation of being a signaling mediator with many diverse and often opposing biological activities. The diversity in response to this simple diatomic molecule comes ...from the enormous variety of chemical reactions and biological properties associated with it. In the past few years, the importance of steady-state NO concentrations has emerged as a key determinant of its biological function. Precise cellular responses are differentially regulated by specific NO concentration. We propose five basic distinct concentration levels of NO activity: cGMP-mediated processes (NO
<
1–30 nM), Akt phosphorylation (NO = 30–100 nM), stabilization of HIF-1α (NO = 100–300 nM), phosphorylation of p53 (NO
>
400 nM), and nitrosative stress (1 μM). In general, lower NO concentrations promote cell survival and proliferation, whereas higher levels favor cell cycle arrest, apoptosis, and senescence. Free radical interactions will also influence NO signaling. One of the consequences of reactive oxygen species generation is to reduce NO concentrations. This antagonizes the signaling of nitric oxide and in some cases results in converting a cell-cycle arrest profile to a cell survival profile. The resulting reactive nitrogen species that are generated from these reactions can also have biological effects and increase oxidative and nitrosative stress responses. A number of factors determine the formation of NO and its concentration, such as diffusion, consumption, and substrate availability, which are referred to as kinetic determinants for molecular target interactions. These are the chemical and biochemical parameters that shape cellular responses to NO. Herein we discuss signal transduction and the chemical biology of NO in terms of the direct and indirect reactions.
There is considerable need for accurate suicide risk assessment for clinical, screening, and research purposes. This study applied the tripartite affect-behavior-cognition theory, the suicidal ...barometer model, classical test theory, and item response theory (IRT), to develop a brief self-report measure of suicide risk that is theoretically-grounded, reliable and valid. An initial survey (n = 359) employed an iterative process to an item pool, resulting in the six-item Suicidal Affect-Behavior-Cognition Scale (SABCS). Three additional studies tested the SABCS and a highly endorsed comparison measure. Studies included two online surveys (Ns = 1007, and 713), and one prospective clinical survey (n = 72; Time 2, n = 54). Factor analyses demonstrated SABCS construct validity through unidimensionality. Internal reliability was high (α = .86-.93, split-half = .90-.94)). The scale was predictive of future suicidal behaviors and suicidality (r = .68, .73, respectively), showed convergent validity, and the SABCS-4 demonstrated clinically relevant sensitivity to change. IRT analyses revealed the SABCS captured more information than the comparison measure, and better defined participants at low, moderate, and high risk. The SABCS is the first suicide risk measure to demonstrate no differential item functioning by sex, age, or ethnicity. In all comparisons, the SABCS showed incremental improvements over a highly endorsed scale through stronger predictive ability, reliability, and other properties. The SABCS is in the public domain, with this publication, and is suitable for clinical evaluations, public screening, and research.
Inducible nitric oxide synthase (NOS2) is involved in wound healing, angiogenesis, and carcinogenesis. NOS2 upregulation and increased nitric oxide (NO) production affect the redox state of cells and ...can induce protein, lipid, and DNA modifications. To investigate whether NOS2 levels influence survival of breast cancer patients, we examined NOS2 expression and its association with tumor markers and survival in 248 breast tumors. In multivariable survival analysis, increased NOS2 predicted inferior survival in women with estrogen receptor α-negative (ER-negative) tumors. Microdissected tumor epithelium from ER-negative tumors with high NOS2 had increased IL-8 and a gene expression signature characteristic of basal-like breast cancer with poor prognosis. In cell culture, NO only induced selected signature genes in ER-negative breast cancer cells. ER transgene expression in ER-negative cells inhibited NO-induced upregulation of the stem cell marker CD44 and other proteins encoded by signature genes, but not of IL-8. Exposure to NO also enhanced cell motility and invasion of ER-negative cells. Last, pathway analysis linked the tumor NOS2 gene signature to c-Myc activation. Thus, NOS2 is associated with a basal-like transcription pattern and poor survival of ER-negative patients.
Background
Otolaryngologists are among the highest risk for COVID‐19 exposure.
Methods
This is a cross‐sectional, survey‐based, national study evaluating academic otolaryngologists. Burnout, anxiety, ...distress, and depression were assessed by the single‐item Mini‐Z Burnout Assessment, 7‐item Generalized Anxiety Disorder Scale, 15‐item Impact of Event Scale, and 2‐item Patient Health Questionnaire, respectively.
Results
A total of 349 physicians completed the survey. Of them, 165 (47.3%) were residents and 212 (60.7%) were males. Anxiety, distress, burnout, and depression were reported in 167 (47.9%), 210 (60.2%), 76 (21.8%), and 37 (10.6%) physicians, respectively. Attendings had decreased burnout relative to residents (odds ratio OR 0.28, confidence interval CI 0.11‐0.68; P = .005). Females had increased burnout (OR 1.93, CI 1.12.‐3.32; P = .018), anxiety (OR 2.53, CI 1.59‐4.02; P < .005), and distress (OR 2.68, CI 1.64‐4.37; P < .005). Physicians in states with greater than 20 000 positive cases had increased distress (OR 2.01, CI 1.22‐3.31; P = .006).
Conclusion
During the COVID‐19 pandemic, the prevalence of burnout, anxiety, and distress is high among academic otolaryngologists.
Attempts to associate amyloid-β (Aβ) pathogenesis with synaptic loss in Alzheimer's disease (AD) have thus far been limited to small numbers of postmortem studies. Aβ plaque burden is not ...well-correlated with indices of clinical severity or neurodegeneration-at least in the dementia stage-as deposition of Aβ reaches a ceiling. In this study, we examined in vivo the association between fibrillar Aβ deposition and synaptic density in early AD using positron emission tomography (PET). We hypothesized that global Aβ deposition would be more strongly inversely associated with hippocampal synaptic density in participants with amnestic mild cognitive impairment (aMCI; a stage of continued Aβ accumulation) compared to those with dementia (a stage of relative Aβ plateau).
We measured SV2A binding (
CUCB-J) and Aβ deposition (
CPiB) in 14 participants with aMCI due to AD and 24 participants with mild AD dementia. Distribution volume ratios (DVR) with a cerebellar reference region were calculated for both tracers to investigate the association between global Aβ deposition and SV2A binding in hippocampus. Exploratory analyses examined correlations between both global and regional Aβ deposition and SV2A binding across a broad range of brain regions using both ROI- and surface-based approaches.
We observed a significant inverse association between global Aβ deposition and hippocampal SV2A binding in participants with aMCI (r = - 0.55, P = 0.04), but not mild dementia (r = 0.05, P = 0.82; difference statistically significant by Fisher z = - 1.80, P = 0.04). Exploratory analyses across other ROIs and whole brain analyses demonstrated no broad or consistent associations between global Aβ deposition and regional SV2A binding in either diagnostic group. ROI-based analyses of the association between regional Aβ deposition and SV2A binding also revealed no consistent pattern but suggested a "paradoxical" positive association between local Aβ deposition and SV2A binding in the hippocampus.
Our findings lend support to a model in which fibrillar Aβ is still accumulating in the early stages of clinical disease but approaching a relative plateau, a point at which Aβ may uncouple from neurodegenerative processes including synaptic loss. Future research should investigate the relationship between Aβ deposition and synaptic loss in larger cohorts beginning preclinically and followed longitudinally in conjunction with other biomarkers.
We report the solid-state structural properties of alloxazine, a tricyclic ring system found in many biologically important molecules, with structure determination carried out directly from powder ...X-ray diffraction (XRD) data. As the crystal structures containing the alloxazine and isoalloxazine tautomers both give a high-quality fit to the powder XRD data in Rietveld refinement, other techniques are required to establish the tautomeric form in the solid state. In particular, high-resolution solid-state 15N NMR data support the presence of the alloxazine tautomer, based on comparison between isotropic chemical shifts in the experimental 15N NMR spectrum and the corresponding values calculated for the crystal structures containing the alloxazine and isoalloxazine tautomers. Furthermore, periodic DFT-D calculations at the PBE0-MBD level indicate that the crystal structure containing the alloxazine tautomer has significantly lower energy. We also report computational investigations of the interconversion between the tautomeric forms in the crystal structure via proton transfer along two intermolecular N–H···N hydrogen bonds; DFT-D calculations at the PBE0-MBD level indicate that the tautomeric interconversion is associated with a lower energy transition state for a mechanism involving concerted (rather than sequential) proton transfer along the two hydrogen bonds. However, based on the relative energies of the crystal structures containing the alloxazine and isoalloxazine tautomers, it is estimated that under conditions of thermal equilibrium at ambient temperature, more than 99.9% of the molecules in the crystal structure will exist as the alloxazine tautomer.
Given the long-term human habitation and prolific land use change trajectories in the eastern United States, few remnants of the pre-European settlement Mid-Atlantic forest remain on the Atlantic ...Coastal Plain. This study utilized metes and bounds witness tree locations and descriptions produced during colonial land subdivision to understand the relationships between tree types and biogeographic environments for an area on Maryland's Eastern Shore. Using correspondence analysis, we reveal habitat partitioning among witness tree species based on soil drainage characteristics, that enable the visualization of a pre-European settlement reconstructed forest. Our research finds that oak (Quercus), most often white oak (Quercus alba), was the dominant genus for most of the study area underlain by well-drained soils. To a much smaller extent, gums were also associated with these well-drained soils. Areas of poor drainage most often contained pine (Finns) and an assemblage of different oaks (Quercus spp.). Hickory (Carya), also noted in the witness tree record in small numbers, was found across all soil drainages.
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