Spontaneous mesenteric hematoma: Case report and review literature of a rare clinical entity.

Spontaneous mesenteric hematomas (SMH) are not a common entity. Here we describe a case of 64 year old woman who presented with a vague abdominal pain and diffuse tenderness. Her CT abdomen revealed an ill-defined hyperdense mass like lesion in the mesentery and she underwent exploratory laparotomy which revealed a large hematoma in the mesentery with inflammation of the adjoining small bowel loop. Histopathology revealed findings consistent with hematoma with no evidence of neoplastic lesion.

New robotic platform for transoral robotic surgery: an IDEAL stage 0 study.

Objectives: This study aims to assess the feasibility to perform transoral robotic surgery (TORS) with a new robotic platform, the Versius Surgical System (CMR Surgical, UK) in a preclinical cadaveric setting in accordance to stage 0 of the IDEAL-D framework. Design: IDEAL stage 0 preclinical assessment of the Versius Robotic System in TORS in human cadavers. Setting: All procedures were performed in a simulated operating theatre environment at a UK surgical training centre. Participants: 11 consultant head and neck surgeons from the UK, mainland Europe and the USA took part in TORS procedures on six human cadavers. Interventions: 3 key index procedures were assessed that represent the core surgical workload of TORS: lateral oropharyngectomy, tongue base resection and partial supraglottic laryngectomy. Main outcome measures: The primary outcome was the successful completion of each surgical procedure. Secondary outcomes included the optimisation of system setup, instrumentation and surgeon-reported outcomes for feasibility of each component procedural step. Results: 33 cadaveric procedures were performed and 32 were successfully completed. One supraglottic laryngectomy was not fully completed due to issues dividing the epiglottic cartilage with available instrumentation. Surgeon-reported outcomes met the minimal level of feasibility in all procedures and a consensus that it is feasible to perform TORS with Versius was reached. Available instrumentation was not representative of other robotic platforms used in TORS and further instrument optimisation is recommended before wider dissemination. Conclusions: It is feasible to perform TORS with the Versius Surgical System (CMR Surgical) within a pre-clinical cadaveric setting. Clinical evaluation is needed and appropriate with the system. Further instrument development and optimisation is desirable.

Heart Team Approach for Cardiogenic Shock Management in Pregnancy Complicated by Mechanical Mitral Valve Thrombosis.

A 27-year-old pregnant woman at 24 weeks of gestation was admitted with cardiogenic shock due to mechanical mitral valve thrombosis. Following discussion with the heart team, thrombolysis was achieved with tissue plasminogen activator therapy followed by heparin infusion. Ultimately, the patient required mitral valve replacement for persistently elevated gradients.

Characteristics of Right Ventricular to Pulmonary Arterial Coupling and Association With Functional Status Among Older Aged Adults from the Multi-Ethnic Study of Atherosclerosis.

Although the echocardiographic:derived ratio of tricuspid annular plane systolic excursion (TAPSE) to pulmonary arterial systolic pressure (PASP) is an important prognostic tool in heart failure (HF), the relation with 6-minute walk distance (6MWD) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) is less established. We sought to establish the normative values of TAPSE:PASP among older adults without cardiovascular disease (CVD) and evaluate the relation with NT-proBNP and 6MWD. Among 1,542 participants of the Multi-Ethnic Study of Atherosclerosis-HF ancillary study, the cross-sectional association of TAPSE:PASP with the outcomes of 6MWD and NT-proBNP was analyzed using multivariable linear regression, with progressive adjustment for sociodemographic and CVD risk factors. Our cohort had a mean age (SD) of 73 ± 8 years, 55% women, and a mean TAPSE:PASP ratio of 0.68 ± 0.16. In the unadjusted analysis, increasing tertiles of TAPSE:PASP were associated with younger age, less diabetes, higher estimated glomerular filtration rate, and less antihypertensive medication use. The TAPSE:PASP ratio significantly correlated with both 6MWD and NT-proBNP in the fully adjusted models. A 1-unit increment in TAPSE:PASP was associated with an adjusted 9.9% (4.8% to 15.2%) higher 6MWD, whereas a 1-unit increment in TAPSE:PASP was associated with an adjusted 38.0% (16.0% to 54.2%) lower NT-proBNP. There was a significant gender interaction of the association of TAPSE:PASP ratio and 6MWD, with stronger association seen in women. Among multiethnic older adults free of clinical CVD, the TAPSE:PASP ratio decreased with age, especially in women and was associated with decreased 6MWD and increasing NT-proBNP, the markers of subclinical HF.

Chronic Unexplained Vomiting: A Case Report on Psychogenic Vomiting.

Psychogenic vomiting is defined as recurrent vomiting without any known discernible organic reasons, or functional vomiting occurring from psychological stress. The overall clinical presentation of psychogenic vomiting suggests a wide range of disability levels, such as stress disorders, mood changes, depression, sexual problems, personality disorders, learned responses, conversion disorders, and illness problems. Non-pharmacological treatment modalities are important as medication for psychogenic vomiting such as individual and group psychotherapy, supportive and behavioral therapy, and family and marital therapy. In this case report, a 25-year-old male with schizophrenia on medication presented to an outpatient clinic with the primary complaint of recurrent vomiting. After ruling out pathologic and physiologic causes of vomiting. It was classified as psychogenic vomiting.

Unsupervised machine learning demonstrates the prognostic value of TAPSE/PASP ratio among hospitalized patients with COVID-19.

BACKGROUND: The ratio of tricuspid annular plane systolic excursion (TAPSE) to pulmonary artery systolic pressure (PASP) is a validated index of right ventricular-pulmonary arterial (RV-PA) coupling with prognostic value. We determined the predictive value of TAPSE/PASP ratio and adverse clinical outcomes in hospitalized patients with COVID-19. METHODS: Two hundred and twenty-nine consecutive hospitalized racially/ethnically diverse adults (≥18 years of age) admitted with COVID-19 between March and June 2020 with clinically indicated transthoracic echocardiograms (TTE) that included adequate tricuspid regurgitation (TR) velocities for calculation of PASP were studied. The exposure of interest was impaired RV-PA coupling as assessed by TAPSE/PASP ratio. The primary outcome was in-hospital mortality. Secondary endpoints comprised of ICU admission, incident acute respiratory distress syndrome (ARDS), and systolic heart failure. RESULTS: One hundred and seventy-six patients had both technically adequate TAPSE measurements and measurable TR velocities for analysis. After adjustment for age, sex, BMI, race/ethnicity, diabetes mellitus, and smoking status, log(TAPSE/PASP) had a significantly inverse association with ICU admission (p = 0.015) and death (p = 0.038). ROC analysis showed the optimal cutoff for TAPSE/PASP for death was 0.51 mm mmHg-1 (AUC = 0.68). Unsupervised machine learning identified two groups of echocardiographic function. Of all echocardiographic measures included, TAPSE/PASP ratio was the most significant in predicting in-hospital mortality, further supporting its significance in this cohort. CONCLUSION: Impaired RV-PA coupling, assessed noninvasively via the TAPSE/PASP ratio, was predictive of need for ICU level care and in-hospital mortality in hospitalized patients with COVID-19 suggesting utility of TAPSE/PASP in identification of poor clinical outcomes in this population both by traditional statistical and unsupervised machine learning based methods.

Posttranslational modifications optimize the ability of SARS-CoV-2 spike for effective interaction with host cell receptors.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike glycoprotein is the prime target for vaccines, diagnostics, and therapeutic antibodies against the virus. While anchored in the viral envelope, for effective virulence, the spike needs to maintain structural flexibility to recognize the host cell surface receptors and bind to them, a property that can heavily depend upon the dynamics of the unresolved domains, most prominently the stalk. Construction of the complete, membrane-bound spike model and the description of its dynamics are critical steps in understanding the inner working of this key element of the viral infection by SARS-CoV-2. Combining homology modeling, protein-protein docking, and molecular dynamics (MD) simulations, we have developed a full spike structure in a native membrane. Multimicrosecond MD simulations of this model, the longest known single trajectory of the full spike, reveal conformational dynamics employed by the protein to explore the surface of the host cell. In agreement with cryogenic electron microscopy (cryo-EM), three flexible hinges in the stalk allow for global conformational heterogeneity of spike in the fully glycosylated system mediated by glycan-glycan and glycan-lipid interactions. The dynamical range of the spike is considerably reduced in its nonglycosylated form, confining the area explored by the spike on the host cell surface. Furthermore, palmitoylation of the membrane domain amplifies the local curvature that may prime the fusion. We show that the identified hinge regions are highly conserved in SARS coronaviruses, highlighting their functional importance in enhancing viral infection, and thereby, provide points for discovery of alternative therapeutics against the virus.

Omega-3 fatty acids, subclinical atherosclerosis, and cardiovascular events: Implications for primary prevention.

BACKGROUND AND AIMS: High-dose eicosapentaenoic acid (EPA) therapy was beneficial in high-risk patients without clinical cardiovascular disease (CVD). Whether higher plasma levels of EPA and docosahexaenoic acid (DHA) have similar benefits in those without subclinical CVD is unclear. We aim to evaluate the interplay between plasma omega-3 fatty acids and coronary artery calcium (CAC) in relation to CVD events. METHODS: We examined 6568 participants from the Multi-Ethnic Study of Atherosclerosis (MESA) with plasma EPA and DHA levels and CAC measured at baseline. The primary outcome was incident CVD events (myocardial infarction, angina, cardiac arrest, stroke, CVD death). Hazard ratios for the primary outcome were adjusted for potential confounder using Cox regression. RESULTS: Mean ± SD age was 62.1 ± 10.2 years and 52.9% were females. The median follow-up time was 15.6 years. Higher loge(EPA) (adjusted hazard ratio, aHR = 0.83; 95% CI, 0.74-0.94) and loge(DHA) (aHR = 0.79; 95% CI, 0.66-0.96) were independently associated with fewer CVD events. The difference in absolute CVD event rates between lowest vs. highest EPA tertile increased at higher CAC levels. The adjusted HR for highest vs. lowest EPA tertile within CAC = 0 was 1.02 (95% CI, 0.72-1.46), CAC = 1-99 was 0.71 (95% CI, 0.51-0.99), and CAC≥100 was 0.67 (95% CI, 0.52-0.84). A similar association was seen in tertiles of DHA by CAC category. CONCLUSIONS: In an ethnically diverse population free of clinical CVD, higher plasma omega-3 fatty acid levels were associated with fewer long-term CVD events. The absolute decrease in CVD events with higher omega-3 fatty acid levels was more apparent at higher CAC scores.

Extended-ensemble docking to probe dynamic variation of ligand binding sites during large-scale structural changes of proteins.

Proteins can sample a broad landscape as they undergo conformational transition between different functional states. At the same time, as key players in almost all cellular processes, proteins are important drug targets. Considering the different conformational states of a protein is therefore central for a successful drug-design strategy. Here we introduce a novel docking protocol, termed extended-ensemble docking, pertaining to proteins that undergo large-scale (global) conformational changes during their function. In its application to multidrug ABC-transporter P-glycoprotein (Pgp), extensive non-equilibrium molecular dynamics simulations employing system-specific collective variables are first used to describe the transition cycle of the transporter. An extended set of conformations (extended ensemble) representing the full transition cycle between the inward- and the outward-facing states is then used to seed high-throughput docking calculations of known substrates, non-substrates, and modulators of the transporter. Large differences are predicted in the binding affinities to different conformations, with compounds showing stronger binding affinities to intermediate conformations compared to the starting crystal structure. Hierarchical clustering of the binding modes shows all ligands preferably bind to the large central cavity of the protein, formed at the apex of the transmembrane domain (TMD), whereas only small binding populations are observed in the previously described R and H sites present within the individual TMD leaflets. Based on the results, the central cavity is further divided into two major subsites, first preferably binding smaller substrates and high-affinity inhibitors, whereas the second one shows preference for larger substrates and low-affinity modulators. These central subsites along with the low-affinity interaction sites present within the individual TMD leaflets may respectively correspond to the proposed high- and low-affinity binding sites in Pgp. We propose further an optimization strategy for developing more potent inhibitors of Pgp, based on increasing its specificity to the extended ensemble of the protein, instead of using a single protein structure, as well as its selectivity for the high-affinity binding site. In contrast to earlier in silico studies using single static structures of Pgp, our results show better agreement with experimental studies, pointing to the importance of incorporating the global conformational flexibility of proteins in future drug-discovery endeavors.

Tracheal Invasion and Cardiopulmonary Compromise From Primary Thyroid Lymphoma.

Rapidly expanding thyroid lesions with tracheal invasion are typical characteristics of anaplastic and undifferentiated thyroid carcinomas, but primary thyroid lymphoma (PTL) must also be considered as a differential. Aggressive thyroid lesions can compromise the airway through compression and/or direct invasion of the tracheal wall. We present a rare case of PTL in a 57-year-old female patient who presented with worsening orthopnoea and hoarseness, followed by shortness of breath, secondary to direct invasion and compression of the trachea resulting in pulmonary edema and cardiomyopathy, requiring intensive care input. In view of the extent of the disease and associated repercussions, the patient underwent total thyroidectomy and chemotherapy, as part of her therapeutic regime, with metabolic and cardiovascular remission achieved. Histological diagnosis confirmed diffuse large B-cell lymphoma (DLBCL). PTL is a rare condition, with few cases reported in the literature. Fine needle aspiration cytology (FNAC) used traditionally in the diagnosis of thyroid lesions is less informative in PTL and core needle and incisional biopsy techniques, coupled with CT, can provide diagnostic clarity. Due to the unusual nature of PTL, it can pose diagnostic and management difficulties. Further studies are required and a multi-professional tailored approach should be adopted for each patient until a therapeutic consensus can be reached.

Ultra-High-Resolution Coronary CT Angiography for Assessment of Patients with Severe Coronary Artery Calcification: Initial Experience.

PURPOSE: Conventional CT technology yields only modest accuracy of coronary artery stenosis assessment in severely calcified lesions. Reported herein are this study's initial observations on the potential of ultra-high-resolution CT (UHR-CT) for evaluating severely calcified coronary arterial lesions. MATERIALS AND METHODS: Fifteen patients 45 years of age or older, with history of coronary artery disease, referred for invasive coronary angiography, were prospectively enrolled. Patients underwent UHR-CT within 30 days prior to cardiac catheterization. Image noise levels and diagnostic confidence (level 1-5) using UHR-CT were compared with reconstructed images simulating conventional CT technology. Stenosis assessment for the major coronary arteries and the left main coronary artery with UHR-CT and invasive angiography were compared. Results from clinically driven coronary CT using conventional technology were considered for comparison when available. RESULTS: Mean patient age was 67 years (range, 53-79 years). Thirteen patients were men, nine had obesity. Radiation dose was 9.3 mSv owing to expanded x-ray exposure to accommodate research software application (70%-99% of R-R cycle). Overall image noise was considerably greater for UHR-CT (50.9 ± 7.8 [standard deviation]) versus conventional CT image reconstruction (19.5 ± 8.3, P < .01), yet diagnostic confidence scores for UHR-CT were high (4.3 ± 0.9). Average calcium score in patients without stents (n = 6) was 1205, and of 86 vessels evaluated, 22 had 70% or greater stenosis depicted with invasive angiography (26%). Stenosis comparison with invasive angiography yielded 86% (19 of 22) sensitivity and 88% (56 of 64) specificity (95% CI: 65%, 97%; and 77%, 95%, respectively). CONCLUSION: Initial observations suggest UHR-CT may be effective in overcoming the limitation of conventional CT for accurately evaluating coronary artery stenoses in severely calcified vessels.Keywords: CT-Angiography, Coronary Arteries, ArteriosclerosisClinical trial registration no. NCT04272060See also commentary by Shanbhag and Chen in this issue.© RSNA, 2021.

Update on the omega-3 fatty acid trial landscape: A narrative review with implications for primary prevention.

Residual risk mediated by hypertriglyceridemia among statin-treated individuals is an important clinical and public health challenge. Niacin, fibrates and omega-3 FA are three classes of non-statin agents with demonstrated TG-lowering effects. Randomized controlled trials of niacin and fibrates have been consistently negative, but the trial landscape for two key sources of omega-3 FAs, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) is more complex. Clinical trials evaluating omega-3 FA can be differentiated into those that studied mixed formulations (EPA + DHA) and those that studied EPA alone. Those assessing the impact of mixed formulations have not consistently demonstrated CVD risk reduction, whereas trials of EPA alone have been successful. Two recent trials of mixed formulations - STRENGTH (Long-Term Outcomes Study to Assess Statin Residual Risk with Epanova in High Cardiovascular Risk Patients with Hypertriglyceridemia) and OMEMI (Omega-3 fatty acids in Elderly patients with Myocardial Infarction) - studied contemporarily treated patients with mixed EPA + DHA formulations at higher doses than before and showed no benefit, thus adding valuable information to our overall understanding of this evolving therapeutic class. In this review, we contextualize the findings of STRENGTH and OMEMI within the existing omega-3 FA clinical trial landscape and look ahead to how future trials can inform existing knowledge gaps, particularly with regards to the applicability of these agents within the primary prevention realm.

Active participation of membrane lipids in inhibition of multidrug transporter P-glycoprotein.

P-glycoprotein (Pgp) is a major efflux pump in humans, overexpressed in a variety of cancers and associated with the development of multi-drug resistance. Allosteric modulation by various ligands (e.g., transport substrates, inhibitors, and ATP) has been biochemically shown to directly influence structural dynamics, and thereby, the function of Pgp. However, the molecular details of such effects, particularly with respect to the role and involvement of the surrounding lipids, are not well established. Here, we employ all-atom molecular dynamics (MD) simulations to study the conformational landscape of Pgp in the presence of a high-affinity, third-generation inhibitor, tariquidar, in comparison to the nucleotide-free (APO) and the ATP-bound states, in order to characterize the mechanical effects of the inhibitor that might be of relevance to its blocking mechanism of Pgp. Simulations in a multi-component lipid bilayer show a dynamic equilibrium between open(er) and more closed inward-facing (IF) conformations in the APO state, with binding of ATP shifting the equilibrium towards conformations more prone to ATP hydrolysis and subsequent events in the transport cycle. In the presence of the inhibitor bound to the drug-binding pocket within the transmembrane domain (TMD), Pgp samples more open IF conformations, and the nucleotide binding domains (NBDs) become highly dynamic. Interestingly, and reproduced in multiple independent simulations, the inhibitor is observed to facilitate recruitment of lipid molecules into the Pgp lumen through the two proposed drug-entry portals, where the lipid head groups from the cytoplasmic leaflet penetrate into and, in some cases, translocate inside the TMD, while the lipid tails remain extended into the bulk lipid environment. These "wedge" lipids likely enhance the inhibitor-induced conformational restriction of the TMD leading to the differential modulation of coupling pathways observed with the NBDs downstream. We suggest a novel inhibitory mechanism for tariquidar, and potentially for related third-generation Pgp inhibitors, where lipids are seen to enhance the inhibitory role in the catalytic cycle of membrane transporters.

Association Between Omega-3 Fatty Acid Levels and Risk for Incident Major Bleeding Events and Atrial Fibrillation: MESA.

Background Randomized trials of pharmacologic strength omega-3 fatty acid (n3-FA)-based therapies suggest a dose-dependent cardiovascular benefit. Whether blood n3-FA levels also mediate safety signals observed in these trials, such as increased bleeding and atrial fibrillation (AF), remains uncertain. We hypothesized that higher baseline n3-FA levels would be associated with incident bleeding and AF events in MESA (Multi-Ethnic Study of Atherosclerosis), which included a population free of clinical cardiovascular disease at baseline. Methods and Results We examined the association between baseline plasma n3-FA levels (expressed as percent mass of total fatty acid) with incident bleeding and AF in MESA, an ongoing prospective cohort study. Bleeding events were identified from review of hospitalization International Classification of Diseases, Ninth Revision (ICD-9), and International Classification of Diseases, Tenth Revision (ICD-10), codes, and AF from participant report, discharge diagnoses, Medicare claims data, and study ECGs performed at MESA visit 5. Separate multivariable Cox proportional hazard modeling was used to estimate hazard ratios of the association of continuous n3-FA (log eicosapentaenoic acid [EPA], log docosahexaenoic acid [DHA], log [EPA+DHA]) and incident hospitalized bleeding events and AF. Among 6546 participants, the mean age was 62.1 years and 53% were women. For incident bleeding, consistent statistically significant associations with lower rates were seen with increasing levels of EPA and EPA+DHA in unadjusted and adjusted models including medications that modulate bleeding risk (aspirin, NSAIDS, corticosteroids, and proton pump inhibitors). For incident AF, a significant association with lower rates was seen with increasing levels of DHA, but not for EPA or EPA+DHA. Conclusions In MESA, higher plasma levels of n3-FA (EPA and EPA+DHA, but not DHA) were associated with significantly fewer hospitalized bleeding events, and higher DHA levels (but not EPA or EPA+DHA) with fewer incident AF events.

Anomalous Origin of the Right Coronary Artery Causing Myocardial Ischemia: A Case for a Multimodality Imaging Approach.

A 46-year-old man was admitted with non-ST elevation myocardial infarction and newly diagnosed acutely decompensated heart failure. Echocardiogram demonstrated left ventricular ejection fraction of 30% with basal inferior and inferolateral akinesis. Coronary angiography showed mild diffuse coronary artery disease and an anomalous right coronary artery arising from the left coronary cusp. Further imaging was consistent with ischemia in the right coronary distribution. Etiology of ischemia was thought to be the anomalous right coronary artery, and surgical unroofing of the right coronary ostium was performed. Here, we report a multimodality imaging approach, including cardiac magnetic resonance, cardiac computed tomographic angiography, and single-photon emission computed tomography, to support the diagnosis and management of a patient with anomalous right coronary artery arising from the left coronary cusp.

Understanding Immigration as a Social Determinant of Health: Cardiovascular Disease in Hispanics/Latinos and South Asians in the United States.

PURPOSE OF REVIEW: The main purpose of this review is to summarize the epidemiology of cardiovascular disease and its risk factors among two of the largest and most diverse immigrant groups in the United States (Hispanics/Latinos and South Asians). RECENT FINDINGS: While the migration process generates unique challenges for individuals, there is a wide heterogeneity in the characteristics of immigrant populations, both between and within regions of origin. Hispanic/Latino immigrants to the United States have lower levels of cardiovascular risk factors, prevalence, and mortality, but this assessment is limited by issues related to the "salmon bias." South Asian immigrants to the United States generally have higher levels of risk factors and higher mortality. In both cases, levels of risk factors and mortality generally increase with time of living in the United States (US). While immigration acts as a social determinant of health, associations between immigration and cardiovascular disease and its risk factors are complex and vary across subpopulations.

Binding mode of SARS-CoV-2 fusion peptide to human cellular membrane.

Infection of human cells by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) relies on its binding to a specific receptor and subsequent fusion of the viral and host cell membranes. The fusion peptide (FP), a short peptide segment in the spike protein, plays a central role in the initial penetration of the virus into the host cell membrane, followed by the fusion of the two membranes. Here, we use an array of molecular dynamics simulations that take advantage of the highly mobile membrane mimetic model to investigate the interaction of the SARS-CoV2 FP with a lipid bilayer representing mammalian cellular membranes at an atomic level and to characterize the membrane-bound form of the peptide. Six independent systems were generated by changing the initial positioning and orientation of the FP with respect to the membrane, and each system was simulated in five independent replicas, each for 300 ns. In 73% of the simulations, the FP reaches a stable, membrane-bound configuration, in which the peptide deeply penetrated into the membrane. Clustering of the results reveals three major membrane-binding modes (binding modes 1-3), in which binding mode 1 populates over half of the data points. Taking into account the sequence conservation among the viral FPs and the results of mutagenesis studies establishing the role of specific residues in the helical portion of the FP in membrane association, the significant depth of penetration of the whole peptide, and the dense population of the respective cluster, we propose that the most deeply inserted membrane-bound form (binding mode 1) represents more closely the biologically relevant form. Analysis of FP-lipid interactions shows the involvement of specific residues, previously described as the "fusion-active core residues," in membrane binding. Taken together, the results shed light on a key step involved in SARS-CoV2 infection, with potential implications in designing novel inhibitors.

Prediction of Mortality in hospitalized COVID-19 patients in a statewide health network.

Importance: A predictive model to automatically identify the earliest determinants of both hospital discharge and mortality in hospitalized COVID-19 patients could be of great assistance to caregivers if the predictive information is generated and made available in the immediate hours following admission. Objective: To identify the most important predictors of hospital discharge and mortality from measurements at admission for hospitalized COVID-19 patients. Design: Observational cohort study. Setting: Electronic records from hospitalized patients. Participants: Patients admitted between March 3rd and August 24th with COVID-19 in Johns Hopkins Health System hospitals. Exposures: 216 phenotypic variables collected within 48 hours of admission. Main Outcomes: We used age-stratified (<60 and >=60 years) random survival forests with competing risks to identify the most important predictors of death and discharge. Fine-Gray competing risk regression (FGR) models were then constructed based on the most important RSF-derived covariates. Results: Of 2212 patients, 1913 were discharged (age 57±19, time-to-discharge 9±11 days) while 279 died (age 75±14, time to death 14±15 days). Patients >= 60 years were nearly 10 times as likely to die within 60 days of admission as those <60. As the pandemic evolved, the rate of hospital discharge increased in both older and younger patients. Incident death and hospital discharge were accurately predicted by measures of respiratory distress, inflammation, infection, renal function, red cell turn over and cardiac stress. FGR models for each of hospital discharge and mortality as outcomes based on these variables performed well in the older (AUC 0·80-0·85 at 60-days) and younger populations (AUC >0·90 at 60-days). Conclusions and Relevance: We identified markers collected within 2 days of admission that predict hospital discharge and mortality in COVID-19 patients and provide prediction models that may be used to guide patient care. Our proposed model suggests that hospital discharge and mortality can be forecasted with high accuracy based on 8-10 variables at this stage of the COVID-19 pandemic. Our findings also point to several specific pathways that could be the focus of future investigations directed at reducing mortality and expediting hospital discharge among COVID-19 patients. Probability of hospital discharge increased over the course of the pandemic.

The carboxylation status of osteocalcin has important consequences for its structure and dynamics.

BACKGROUND: The carboxylation status of Osteocalcin (Ocn) not only influences formation and structure in bones but also has important endocrine functions affecting energy metabolism and expenditure. In this study, the role of γ-carboxylation of the glutamate residues in the structure-dynamics-function relationship in Ocn is investigated. METHODS: Three forms of Ocn, differentially carboxylated at the Glu-17, 21 and 24 residues, along with a mutated form of Ocn carrying Glu/Ala mutations, are modeled and simulated using molecular dynamics (MD) simulation in the presence of calcium ions. RESULTS: Characterization of the global conformational dynamics of Ocn, described in terms of the orientational variations within its 3-helical domain, highlights large structural variations in the non-carboxylated osteocalcin (nOcn). The bi-carboxylated Ocn (bOcn) and tri-carboxylated (tOcn) species, in contrast, display relatively rigid tertiary structures, with the dynamics of most regions strongly correlated. Radial distribution functions calculated for both bOcn and tOcn show long-range ordering of the calcium ion distribution around the carboxylated glutamate (γGlu) residues, likely playing an important role in promoting stability of these Ocns. Additionally, the same calcium ions are observed to coordinate with neighboring γGlu, better shielding their negative charges and in turn stabilizing these systems more than do the singly coordinating calcium ions observed in the case of nOcn. bOcn is also found to exhibit a more helical C-terminal structure, that has been shown to activate its cellular receptor GPRC6A, highlighting the allosteric role of Ocn carboxylation in modulating the stability and binding potential of the active C-terminal. CONCLUSIONS: The carboxylation status of Ocn as well and its calcium coordination appear to have a direct influence on Ocn structure and dynamics, possibly leading to the known differences in Ocn biological function. GENERAL SIGNIFICANCE: Modification of Ocn sequence or its carboxylation state may provide the blueprint for developing high-affinity peptides targeting its cellular receptor GPRC6A, with therapeutic potential for treatment of metabolic disorders.

Conformational changes in the nucleotide-binding domains of P-glycoprotein induced by ATP hydrolysis.

P-glycoprotein (Pgp) is a member of the ABC transporter superfamily with high physiological importance. Pgp nucleotide-binding domains (NBDs) drive the transport cycle through ATP binding and hydrolysis. We use molecular dynamics simulations to investigate the ATP hydrolysis-induced conformational changes in NBDs. Five systems, including all possible ATP/ADP combinations in the NBDs and the APO system, are simulated. ATP/ADP exchange induces conformational changes mostly within the conserved signature motif of the NBDs, resulting in relative orientational changes in the NBDs. Nucleotide removal leads to additional orientational changes in the NBDs, allowing their dissociation. Furthermore, we capture putative hydrolysis-competent configurations in which the conserved glutamate in the Walker-B motif acts as a catalytic base capturing a water molecule likely initiating ATP hydrolysis.