Caging Bioactive Triarylimidazoles: An Approach to Create Visible Light-Activatable Drugs.

Imidazoles are crucial structural components in a variety of small-molecule inhibitors designed to target different kinases in anticancer treatment. However, the effectiveness of such inhibitors is often hampered by nonspecific effects and the development of resistance. Photopharmacology provides a compelling solution by enabling external control over drug activity with spatiotemporal precision. Herein, we introduce a novel strategy for caging bioactive triarylimidazole-based drug molecules. This approach involves introducing a dialkylamino group as a photoremovable group on the carbon atom of the imidazole ring, which intrinsically modulates the core structure from planar imidazole to tetrahedral 2H-imidazole, enabling the caged compound to be selectively uncaged upon visible light exposure. We applied this innovative caging technique to SB431542, a triarylimidazole-based small-molecule inhibitor that targets the pivotal TGF-ß signaling pathway, the dysregulation of which is linked to several human diseases, including cancer. Our results demonstrated the selective inhibition of human breast cancer cell migration in vitro upon light activation, highlighting the potential of our approach to transform triarylimidazole-based drug molecules into visible light-activatable drugs, thereby facilitating spatiotemporal regulation of their pharmacological activity.

Structural effects of spike protein D614G mutation in SARS-CoV-2.

A single mutation from aspartate to glycine at position 614 has dominated all circulating variants of the severe acute respiratory syndrome coronavirus 2. D614G mutation induces structural changes in the spike (S) protein that strengthen the virus infectivity. Here, we use molecular dynamics simulations to dissect the effects of mutation and 630-loop rigidification on S-protein structure. The introduction of the mutation orders the 630-loop structure and thereby induces global structural changes toward the cryoelectron microscopy structure of the D614G S-protein. The ordered 630-loop weakens local interactions between the 614th residue and others in contrast to disordered structures in the wild-type protein. The mutation allosterically alters global interactions between receptor-binding domains, forming an asymmetric and mobile down conformation and facilitating transitions toward up conformation. The loss of salt bridge between D614 and K854 upon the mutation generally stabilizes S-protein protomer, including the fusion peptide proximal region that mediates membrane fusion. Understanding the molecular basis of D614G mutation is crucial as it dominates in all variants of concern, including Delta and Omicron.

Chaperonin GroEL hydrolyses ortho-nitrophenyl ß-galactoside.

We serendipitously found that chaperonin GroEL can hydrolyze ortho-nitrophenyl ß-galactoside (ONPG), a well-known substrate of the enzyme ß-galactosidase. The ONPG hydrolysis by GroEL follows typical enzyme kinetics. Our experiments and molecular docking studies suggest ONPG binding at the ATP binding site of GroEL.

Global Variations in Heart Failure Etiology, Management, and Outcomes.

Importance: Most epidemiological studies of heart failure (HF) have been conducted in high-income countries with limited comparable data from middle- or low-income countries. Objective: To examine differences in HF etiology, treatment, and outcomes between groups of countries at different levels of economic development. Design, Setting, and Participants: Multinational HF registry of 23 341 participants in 40 high-income, upper-middle-income, lower-middle-income, and low-income countries, followed up for a median period of 2.0 years. Main Outcomes and Measures: HF cause, HF medication use, hospitalization, and death. Results: Mean (SD) age of participants was 63.1 (14.9) years, and 9119 (39.1%) were female. The most common cause of HF was ischemic heart disease (38.1%) followed by hypertension (20.2%). The proportion of participants with HF with reduced ejection fraction taking the combination of a ß-blocker, renin-angiotensin system inhibitor, and mineralocorticoid receptor antagonist was highest in upper-middle-income (61.9%) and high-income countries (51.1%), and it was lowest in low-income (45.7%) and lower-middle-income countries (39.5%) (P < .001). The age- and sex- standardized mortality rate per 100 person-years was lowest in high-income countries (7.8 [95% CI, 7.5-8.2]), 9.3 (95% CI, 8.8-9.9) in upper-middle-income countries, 15.7 (95% CI, 15.0-16.4) in lower-middle-income countries, and it was highest in low-income countries (19.1 [95% CI, 17.6-20.7]). Hospitalization rates were more frequent than death rates in high-income countries (ratio = 3.8) and in upper-middle-income countries (ratio = 2.4), similar in lower-middle-income countries (ratio = 1.1), and less frequent in low-income countries (ratio = 0.6). The 30-day case-fatality rate after first hospital admission was lowest in high-income countries (6.7%), followed by upper-middle-income countries (9.7%), then lower-middle-income countries (21.1%), and highest in low-income countries (31.6%). The proportional risk of death within 30 days of a first hospital admission was 3- to 5-fold higher in lower-middle-income countries and low-income countries compared with high-income countries after adjusting for patient characteristics and use of long-term HF therapies. Conclusions and Relevance: This study of HF patients from 40 different countries and derived from 4 different economic levels demonstrated differences in HF etiologies, management, and outcomes. These data may be useful in planning approaches to improve HF prevention and treatment globally.

Health-Related Quality of Life and Mortality in Heart Failure: The Global Congestive Heart Failure Study of 23 000 Patients From 40 Countries.

BACKGROUND: Poor health-related quality of life (HRQL) is common in heart failure (HF), but there are few data on HRQL in HF and the association between HRQL and mortality outside Western countries. METHODS: We used the Kansas City Cardiomyopathy Questionnaire-12 (KCCQ-12) to record HRQL in 23 291 patients with HF from 40 countries in 8 different world regions in the G-CHF study (Global Congestive Heart Failure). We compared standardized KCCQ-12 summary scores (adjusted for age, sex, and markers of HF severity) among regions (scores range from 0 to 100, with higher score indicating better HRQL). We used multivariable Cox regression with adjustment for 15 variables to assess the association between KCCQ-12 summary scores and the composite of all-cause death, HF hospitalization, and each component over a median follow-up of 1.6 years. RESULTS: The mean age of participants was 65 years; 61% were men; 40% had New York Heart Association class III or IV symptoms; and 46% had left ventricular ejection fraction ≥40%. Average HRQL differed between regions (lowest in Africa [mean± SE, 39.5±0.3], highest in Western Europe [62.5±0.4]). There were 4460 (19%) deaths, 3885 (17%) HF hospitalizations, and 6949 (30%) instances of either event. Lower KCCQ-12 summary score was associated with higher risk of all outcomes; the adjusted hazard ratio (HR) for each 10-unit KCCQ-12 summary score decrement was 1.18 (95% CI, 1.17-1.20) for death. Although this association was observed in all regions, it was less marked in South Asia, South America, and Africa (weakest association in South Asia: HR, 1.08 [95% CI, 1.03-1.14]; strongest association in Eastern Europe: HR, 1.31 [95% CI, 1.21-1.42]; interaction P<0.0001). Lower HRQL predicted death in patients with New York Heart Association class I or II and III or IV symptoms (HR, 1.17 [95% CI, 1.14-1.19] and HR, 1.14 [95% CI, 1.12-1.17]; interaction P=0.13) and was a stronger predictor for the composite outcome in New York Heart Association class I or II versus class III or IV (HR 1.15 [95% CI, 1.13-1.17] versus 1.09 [95% CI, [1.07-1.11]; interaction P<0.0001). HR for death was greater in ejection fraction ≥40 versus <40% (HR, 1.23 [95% CI, 1.20-1.26] and HR, 1.15 [95% CI, 1.13-1.17]; interaction P<0.0001). CONCLUSION: HRQL is a strong and independent predictor of all-cause death and HF hospitalization across all geographic regions, in mildly and severe symptomatic HF, and among patients with preserved and reduced ejection fraction. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03078166.

Modified Protein-Water Interactions in CHARMM36m for Thermodynamics and Kinetics of Proteins in Dilute and Crowded Solutions.

Proper balance between protein-protein and protein-water interactions is vital for atomistic molecular dynamics (MD) simulations of globular proteins as well as intrinsically disordered proteins (IDPs). The overestimation of protein-protein interactions tends to make IDPs more compact than those in experiments. Likewise, multiple proteins in crowded solutions are aggregated with each other too strongly. To optimize the balance, Lennard-Jones (LJ) interactions between protein and water are often increased about 10% (with a scaling parameter, λ = 1.1) from the existing force fields. Here, we explore the optimal scaling parameter of protein-water LJ interactions for CHARMM36m in conjunction with the modified TIP3P water model, by performing enhanced sampling MD simulations of several peptides in dilute solutions and conventional MD simulations of globular proteins in dilute and crowded solutions. In our simulations, 10% increase of protein-water LJ interaction for the CHARMM36m cannot maintain stability of a small helical peptide, (AAQAA)3 in a dilute solution and only a small modification of protein-water LJ interaction up to the 3% increase (λ = 1.03) is allowed. The modified protein-water interactions are applicable to other peptides and globular proteins in dilute solutions without changing thermodynamic properties from the original CHARMM36m. However, it has a great impact on the diffusive properties of proteins in crowded solutions, avoiding the formation of too sticky protein-protein interactions.

Elucidation of interactions regulating conformational stability and dynamics of SARS-CoV-2 S-protein.

The ongoing COVID-19 pandemic caused by the new coronavirus, SARS-CoV-2, calls for urgent developments of vaccines and antiviral drugs. The spike protein of SARS-CoV-2 (S-protein), which consists of trimeric polypeptide chains with glycosylated residues on the surface, triggers the virus entry into a host cell. Extensive structural and functional studies on this protein have rapidly advanced our understanding of the S-protein structure at atomic resolutions, although most of these structural studies overlook the effect of glycans attached to the S-protein on the conformational stability and functional motions between the inactive down and active up forms. Here, we performed all-atom molecular dynamics simulations of both down and up forms of a fully glycosylated S-protein in solution as well as targeted molecular dynamics simulations between them to elucidate key interdomain interactions for stabilizing each form and inducing the large-scale conformational transitions. The residue-level interaction analysis of the simulation trajectories detects distinct amino acid residues and N-glycans as determinants on conformational stability of each form. During the conformational transitions between them, interdomain interactions mediated by glycosylated residues are switched to play key roles on the stabilization of another form. Electrostatic interactions, as well as hydrogen bonds between the three receptor binding domains, work as driving forces to initiate the conformational transitions toward the active form. This study sheds light on the mechanisms underlying conformational stability and functional motions of the S-protein, which are relevant for vaccine and antiviral drug developments.

A multinational registry to study the characteristics and outcomes of heart failure patients: The global congestive heart failure (G-CHF) registry.

The goal of the global congestive heart failure (G-CHF) registry is to collect comparative international data on heart failure characteristics, management, and outcomes and to better understand the determinants that impact the clinical course of heart failure. METHODS: G-CHF is a multicenter, prospective cohort study of adult patients with a new or prior clinical diagnosis of heart failure. We have enrolled 23,047 participants from 257 centers in 40 countries from 8 major geographic regions of the world, with recruitment ongoing. Approximately 4,000 participants will also participate in substudies to assess frailty, comorbidity, diet, barriers to care, biomarkers, and planned detailed echocardiographic analyses. Follow-up is planned for a period of 5 years. The primary outcome is cause-specific mortality. Key secondary outcomes include hospitalizations, quality of life, and major cardiovascular and noncardiovascular outcomes. A total of 31.9% of participants were enrolled as inpatients. Thus far, mean age of the cohort at baseline is 63.1 years, and 60.8% are male. Participants most commonly have heart failure with reduced ejection fraction (53.6%) followed by preserved ejection fraction (24.2%) and midrange ejection fraction (20.6%). The most common causes of heart failure are ischemic (37.8%) followed by hypertensive (20.0%), idiopathic (15.1%), and valvular disease (8.8%). CONCLUSION: G-CHF will provide a greater understanding of the characteristics of the global heart failure population, variations in its management, clinical outcomes, and what continues to impact morbidity and mortality in this high-risk population.

Exploring Large Domain Motions in Proteins Using Atomistic Molecular Dynamics with Enhanced Conformational Sampling.

Conformational transitions in multidomain proteins are essential for biological functions. The Apo conformations are typically open and flexible, while the Holo states form more compact conformations stabilized by protein-ligand interactions. Unfortunately, the atomically detailed mechanisms for such open-closed conformational changes are difficult to be accessed experimentally as well as computationally. To simulate the transitions using atomistic molecular dynamics (MD) simulations, efficient conformational sampling algorithms are required. In this work, we propose a new approach based on generalized replica-exchange with solute tempering (gREST) for exploring the open-closed conformational changes in multidomain proteins. Wherein, selected surface charged residues in a target protein are defined as the solute region in gREST simulation and the solute temperatures are different in replicas and exchanged between them to enhance the domain motions. This approach is called gREST selected surface charged residues (gREST_SSCR) and is applied to the Apo and Holo states of ribose binding protein (RBP) in solution. The conformational spaces sampled with gREST_SSCR are much wider than those with the conventional MD, sampling open-closed conformational changes while maintaining RBP domains' stability. The free-energy landscapes of RBP in the Apo and Holo states are drawn along with twist and hinge angles of the two moving domains. The inter-domain salt-bridges that are not observed in the experimental structures are also important in the intermediate states during the conformational changes.

Randomized controlled trial of influenza vaccine in patients with heart failure to reduce adverse vascular events (IVVE): Rationale and design.

BACKGROUND: Influenza is associated with an increase in the risk of cardiac and other vascular events. Observational data and small randomized trials suggest that influenza vaccination may reduce such adverse vascular events. RESEARCH DESIGN AND METHODS: In a randomized controlled trial patients with heart failure are randomized to receive either inactivated influenza vaccine or placebo annually for 3 years. Patients aged ≥18 years with a clinical diagnosis of heart failure and NYHA functional class II, III and IV are eligible. Five thousand patients from 10 countries where influenza vaccination is not common (Asia, the Middle East, and Africa) have been enrolled. The primary outcome is a composite of the following: cardiovascular death, non-fatal myocardial infarction, non-fatal stroke and hospitalizations for heart failure using standardized criteria. Analyses will be based on comparing event rates between influenza vaccine and control groups and will include time to event, rate comparisons using Poisson methods, and logistic regression. The analysis will be conducted by intention to treat i.e. patients will be analyzed in the group in which they were assigned. Multivariable secondary analyses to assess whether variables such as age, sex, seasonality modify the benefits of vaccination are also planned for the primary outcome. CONCLUSION: This is the largest randomized trial to test if influenza vaccine compared to control reduces adverse vascular events in high risk individuals. TRIAL REGISTRATION NUMBER: Clinicaltrials.govNCT02762851.

Subclinical Atrial Fibrillation in Older Patients.

BACKGROUND: Long-term continuous electrocardiographic monitoring shows a substantial prevalence of asymptomatic, subclinical atrial fibrillation (SCAF) in patients with pacemakers and patients with cryptogenic stroke. Whether SCAF is also common in other patients without these conditions is unknown. METHODS: We implanted subcutaneous electrocardiographic monitors (St. Jude CONFIRM-AF) in patients ≥65 years of age attending cardiovascular or neurology outpatient clinics if they had no history of atrial fibrillation but had any of the following: CHA2DS2-VASc score of ≥2, sleep apnea, or body mass index >30 kg/m2. Eligibility also required either left atrial enlargement (≥4.4 cm or volume ≥58 mL) or increased (≥290 pg/mL) serum NT-proBNP (N-terminal pro-B-type natriuretic peptide). Patients were monitored for SCAF lasting ≥5 minutes. RESULTS: Two hundred fifty-six patients were followed up for 16.3±3.8 months. Baseline age was 74±6 years; mean CHA2DS2-VASc score was 4.1±1.4; left atrial diameter averaged 4.7±0.8 cm; and 48% had a prior stroke, transient ischemic attack, or systemic embolism. SCAF ≥5 minutes was detected in 90 patients (detection rate, 34.4%/y; 95% confidence interval [CI], 27.7-42.3). Baseline predictors of SCAF were increased age (hazard ratio [HR] per decade, 1.55; 95% CI, 1.11-2.15), left atrial dimension (HR per centimeter diameter, 1.43; 95% CI, 1.09-1.86), and blood pressure (HR per 10 mm Hg, 0.87; 95% CI, 0.78-0.98), but not prior stroke. The rate of occurrence of SCAF in those with a history of stroke, systemic embolism, or transient ischemic attack was 39.4%/y versus 30.3%/y without (P=0.32). The cumulative SCAF detection rate was higher (51.9%/y) in those with left atrial volume above the median value of 73.5 mL. CONCLUSIONS: SCAF is frequently detected by continuous electrocardiographic monitoring in older patients without a history of atrial fibrillation who are attending outpatient cardiology and neurology clinics. Its clinical significance is unclear. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01694394.

Functional Conversion of CPD and (6-4) Photolyases by Mutation.

Ultraviolet (UV) light from the sun damages DNA by forming a cyclobutane pyrimidine dimer (CPD) and pyrimidine(6-4)pyrimidone photoproducts [(6-4) PP]. Photolyase (PHR) enzymes utilize near-UV/blue light for DNA repair, which is initiated by light-induced electron transfer from the fully reduced flavin adenine dinucleotide chromophore. Despite similar structures and repair mechanisms, the functions of PHR are highly selective; CPD PHR repairs CPD, but not (6-4) PP, and vice versa. In this study, we attempted functional conversion between CPD and (6-4) PHRs. We found that a triple mutant of (6-4) PHR is able to repair the CPD photoproduct, though the repair efficiency is 1 order of magnitude lower than that of wild-type CPD PHR. Difference Fourier transform infrared spectra for repair demonstrate the lack of secondary structural alteration in the mutant, suggesting that the triple mutant gains substrate binding ability while it does not gain the optimized conformational changes from light-induced electron transfer to the release of the repaired DNA. Interestingly, the (6-4) photoproduct is not repaired by the reverse mutation of CPD PHR, and eight additional mutations (total of 11 mutations) introduced into CPD PHR are not sufficient. The observed asymmetric functional conversion is interpreted in terms of a more complex repair mechanism for (6-4) repair, which was supported by quantum chemical/molecular mechanical calculation. These results suggest that CPD PHR may represent an evolutionary origin for photolyase family proteins.

Assessing hemodynamics noninvasively in patients with heart failure.

PURPOSE OF REVIEW: Describe the contemporary assessment of cardiac hemodynamics using a comprehensive echo-Doppler examination in the heart failure (HF) patient. RECENT FINDINGS: Cardiac flow and filling pressures, on both the left and right sides of the heart, are fundamental to the accurate assessment of the HF patient. Accurate assessment of left ventricular (LV) and right ventricular (RV) systolic and diastolic function is necessary to establish, or exclude, HF as a cause or component of dyspnea in a given patient and to help determine causes of hemodynamic instability in HF patients. Variables such as spectral Doppler (mitral and tricuspid inflow, pulmonary and hepatic venous flow, and pulmonary valve regurgitation signal), tissue Doppler imaging, and speckle tracking, applied to the left and right heart, can help to accurately estimate cardiac hemodynamics. SUMMARY: A comprehensive echocardiogram with Doppler can provide an accurate assessment of left and right heart hemodynamics that is fundamental to the assessment and management of the HF patient.

Heart failure in low- and middle-income countries: background, rationale, and design of the INTERnational Congestive Heart Failure Study (INTER-CHF).

BACKGROUND: Although heart failure (HF) has been referred to as a global epidemic, most HF information comes from high-income countries, with little information about low-income countries (LIC) and middle-income countries (MIC) in Africa, Asia, the Middle East, and South America, which make up the majority of the world's population. METHODS: The INTERnational Congestive Heart Failure Study is a cohort study of 5,813 HF patients enrolled in 108 centers in 16 LIC and MIC. At baseline, data were recorded on sociodemographic and clinical risk factors, HF etiology, laboratory variables, management, and barriers to evidence-based HF care at the patient, physician, and system levels. We sought to enroll consecutive and consenting patients ≥18 years of age with a clinical diagnosis of HF seen in outpatient clinics (2/3 of patients) or inpatient hospital wards (1/3 of patients). Patients were followed up at 6 and 12 months post-enrollment to record clinical status, treatments, and clinical outcomes such as death and hospitalizations. In the 5,813 enrolled HF patients, the mean age was 59 ± 15 years, 40% were female, 62% had a history of hypertension, 30% had diabetes, 21% had prior myocardial infarction, 64% were recruited from outpatient clinics, 36% lived in rural areas, and 29% had HF with preserved left ventricular ejection fraction. CONCLUSIONS: This unique HF registry aims to systematically gather information on sociodemographic and clinical risk factors, etiologies, treatments, barriers to evidence-based care, and outcomes of HF in LIC and MIC. This information will help improve the management of HF globally.

Speckle strain echocardiography predicts outcome in patients with heart failure with both depressed and preserved left ventricular ejection fraction.

BACKGROUND: While speckle imaging has been shown to predict outcome in patients with heart failure (HF), it remains unclear whether speckle strain predicts outcome in patients with HF with preserved ejection fraction (HFPEF). METHODS: Four hundred twenty patients with HF by Framingham criteria and either: left ventricular (LV) EF <50%, or elevated LV filling pressure by comprehensive echo Doppler study in the setting of left ventricular ejection fraction (LVEF) ≥50%, were enrolled. Speckle tracking was used to measure strain and strain rate in multiple vectors. The primary endpoint was HF hospitalization or cardiovascular death. RESULTS: Follow-up was completed in 380/420 patients (90%). The mean age was 55.7 ± 0.8 years, 191/380 (50%) were male, 319/380 (84%) were hypertensive, 183/380 (48%) were diabetic, and 152/380 (40%) had known coronary artery disease. At a mean follow-up of 369 ± 30 days, 107/380 patients (28%) reached the primary endpoint: 97 HF rehospitalizations and 10 cardiac deaths. The best univariate predictors of outcome were global longitudinal peak strain (GLPS) (χ(2) = 25.6, P < 0.001), mitral DT (χ(2) = 16.8, P < 0.001), LVEF (χ(2) = 16.7, P < 0.0001), longitudinal early diastolic strain (χ(2) = 8.7, P = 0.003), and circumferential peak strain (χ(2) = 7.9, P = 0.005). On multivariate analysis, GLPS (P < 0.0001), LVEF (P = 0.0002), and mitral DT (P = 0.005) were independent predictors of outcome. In the 100 HF patients with preserved LVEF, there were 17 events. Patients with GPLS ≤-15 had significantly better event-free survival than patients with GPLS >-15 (χ(2) = 4.1, P = 0.04), whereas LVEF did not predict event-free survival. CONCLUSION: Speckle strain echocardiography is an important predictor of outcome in HF patients with both depressed and preserved LVEF.

Left atrial volume and function in patients with atrial fibrillation.

PURPOSE OF REVIEW: This review of emerging approaches to left atrial imaging in atrial fibrillation is relevant because there has been considerable recent development in the noninvasive characterization of left atrial structure and function. Concurrently, the identification and treatment of atrial fibrillation and the prevention of thromboembolism are evolving. Thus, it is timely to summarize how the advances in these two areas might be synergistic in the treatment of atrial fibrillation. RECENT FINDINGS: This article will summarize recent developments in left atrial imaging that play a role in patients with atrial fibrillation, with particular emphasis on echocardiography, and with reference made to important advances in cardiac computed tomography and cardiac magnetic resonance. The evidence that these modalities can predict who will develop atrial fibrillation, who will achieve sustained sinus rhythm after cardioversion or catheter ablation, and who will have thromboembolic risk will be reviewed. SUMMARY: Although existing evidence is promising, the clinical role of cardiac imaging to predict atrial fibrillation occurrence, atrial fibrillation recurrence after treatment, and thromboembolism from atrial fibrillation remains to be confirmed in large-scale studies and clinical trials.

Computational investigations on the catalytic mechanism of maleate isomerase: the role of the active site cysteine residues.

The maleate isomerase (MI) catalysed isomerization of maleate to fumarate has been investigated using a wide range of computational modelling techniques, including small model DFT calculations, QM-cluster approach, quantum mechanical/molecular mechanical approach (QM/MM in the ONIOM formalism) and molecular dynamics simulations. Several fundamental questions regarding the mechanism were answered in detail, such as the activation and stabilization of the catalytic Cys in a rather hydrophobic active site. The two previously proposed mechanisms were considered, where either enediolate or succinyl-Cys intermediate forms. Small model calculations as well as an ONIOM-based approach suggest that an enediolate intermediate is too unstable. Furthermore, the formation of succinyl-Cys intermediate via the nucleophilic attack of Cys76(-) on the substrate C2 (as proposed experimentally) was found to be energetically unfeasible in both QM-cluster and ONIOM approaches. Instead, our results show that Cys194, upon activation via the substrate, acts as a nucleophile and Cys76 acts as an acid/base catalyst, forming a succinyl-Cys intermediate in a concerted fashion. Indeed, the calculated PA of Cys76 is always higher than that of Cys194 before or upon substrate binding in the active site. Furthermore, the mechanism proceeds via multiple steps by substrate rotation around C2-C3 with the assistance of the now negatively charged Cys76, leading to the formation of fumarate. Finally, our calculated barrier is in good agreement with experiment. These findings represent a novel mechanism in the racemase superfamily.

Incremental value of left ventricular systolic and diastolic function to determine outcome in patients with acute ST-segment elevation myocardial infarction: the echocardiographic substudy of the OASIS-6 trial.

BACKGROUND: The echocardiographic substudy of the OASIS-6 trial evaluated the prognostic implications of left ventricle (LV) systolic and diastolic dysfunction early postacute ST-segment elevation myocardial infarction (STEMI) in patients treated with fondaparinux versus usual care. METHODS: Comprehensive echocardiograms were performed a median of 6 days after the index STEMI in 528 patients, 258 randomized to fondaparinux and 270 to usual care (unfractionated heparin or placebo), to assess LV systolic and diastolic function, LV mass, and LV end-systolic and end-diastolic volumes. A total of 245 (46.4%) patients were followed up for 3 months and 283 (53.6%) for 6 months. Major cardiac events (MACE) were defined as the composite of death, reinfarction, heart failure, or cardiogenic shock and resuscitated cardiac arrest. RESULTS: Patients with LV ejection fraction (LVEF) ≤ 45% and restrictive diastolic function (RDF) were at greatly increased risk of MACE (hazard ratio [HR] = 8.85, 95% CI, 4.21­18.60) compared to patients with LVEF ≥ 45% and without RDF. RDF remained a strong predictor for MACE in patients with LVEF ≥ 45% (HR = 4.38, 95% CI, 1.52­12.60) and in multivariate models adjusted for LVEF, LV end-systolic volume, and clinical variables. CONCLUSION: In this large international trial, LV systolic and diastolic function, as determined by echocardiography early following STEMI, are incremental predictors of MACE. In addition, RDF is a strong independent predictor of MACE after STEMI across a broad range of LVEF.

Pseudo-Luciferase Activity of the SARS-CoV-2 Spike Protein for Cypridina Luciferin.

Enzymatic reactions that involve a luminescent substrate (luciferin) and enzyme (luciferase) from luminous organisms enable a luminescence detection of target proteins and cells with high specificity, albeit that conventional assay design requires a prelabeling of target molecules with luciferase. Here, we report a luciferase-independent luminescence assay in which the target protein directly catalyzes the oxidative luminescence reaction of luciferin. The SARS-CoV-2 antigen (spike) protein catalyzes the light emission of Cypridina luciferin, whereas no such catalytic function was observed for salivary proteins. This selective luminescence reaction is due to the enzymatic recognition of the 3-(1-guanidino)propyl group in luciferin at the interfaces between the units of the spike protein, allowing a specific detection of the spike protein in human saliva without sample pretreatment. This method offers a novel platform to detect virus antigens simply and rapidly without genetic manipulation or antibodies.