Remote Follow-up in a Heart Failure Pragmatic Trial: Insights From the CONNECT-HF.

BACKGROUND: Randomized controlled trials typically require study-specific visits, which can burden participants and sites. Remote follow-up, such as centralized call centers for participant-reported or site-reported, holds promise for reducing costs and enhancing the pragmatism of trials. In this secondary analysis of the CONNECT-HF (Care Optimization Through Patient and Hospital Engagement For HF) trial, we aimed to evaluate the completeness and validity of the remote follow-up process. METHODS AND RESULTS: The CONNECT-HF trial evaluated the effect of a post-discharge quality-improvement intervention for heart failure compared to usual care for up to 1 year. Suspected events were reported either by participants or by health care proxies through a centralized call center or by sites through medical-record queries. When potential hospitalization events were suspected, additional medical records were collected and adjudicated. Among 5942 potential hospitalizations, 18% were only participant-reported, 28% were reported by both participants and sites, and 50% were only site-reported. Concordance rates between the participant/site reports and adjudication for hospitalization were high: 87% participant-reported, 86% both, and 86% site-reported. Rates of adjudicated heart failure hospitalization events among adjudicated all-cause hospitalization were lower but also consistent: 45% participant-reported, 50% both, and 50% site-reported. CONCLUSIONS: Participant-only and site-only reports missed a substantial number of hospitalization events. We observed similar concordance between participant/site reports and adjudication for hospitalizations. Combining participant-reported and site-reported outcomes data is important to capture and validate hospitalizations effectively in pragmatic heart failure trials.

Mobile Application-Based Communication Facilitation Platform for Family Members of Critically Ill Patients: A Randomized Clinical Trial.

Importance: Unmet and racially disparate palliative care needs are common in intensive care unit (ICU) settings. Objective: To test the effect of a primary palliative care intervention vs usual care control both overall and by family member race. Design, Setting, and Participants: This cluster randomized clinical trial was conducted at 6 adult medical and surgical ICUs in 2 academic and community hospitals in North Carolina between April 2019 and May 2022 with physician-level randomization and sequential clusters of 2 Black patient-family member dyads and 2 White patient-family member dyads enrolled under each physician. Eligible participants included consecutive patients receiving mechanical ventilation, their family members, and their attending ICU physicians. Data analysis was conducted from June 2022 to May 2023. Intervention: A mobile application (ICUconnect) that displayed family-reported needs over time and provided ICU attending physicians with automated timeline-driven communication advice on how to address individual needs. Main Outcomes and Measures: The primary outcome was change in the family-reported Needs at the End-of-Life Screening Tool (NEST; range 0-130, with higher scores reflecting greater need) score between study days 1 and 3. Secondary outcomes included family-reported quality of communication and symptoms of depression, anxiety, and posttraumatic stress disorder at 3 months. Results: A total of 111 (51% of those approached) family members (mean [SD] age, 51 [15] years; 96 women [86%]; 15 men [14%]; 47 Black family members [42%]; 64 White family members [58%]) and 111 patients (mean [SD] age, 55 [16] years; 66 male patients [59%]; 45 Black patients [41%]; 65 White patients [59%]; 1 American Indian or Alaska Native patient [1%]) were enrolled under 37 physicians randomized to intervention (19 physicians and 55 patient-family member dyads) or control (18 physicians and 56 patient-family member dyads). Compared with control, there was greater improvement in NEST scores among intervention recipients between baseline and both day 3 (estimated mean difference, -6.6 points; 95% CI, -11.9 to -1.3 points; P = .01) and day 7 (estimated mean difference, -5.4 points; 95% CI, -10.7 to 0.0 points; P = .05). There were no treatment group differences at 3 months in psychological distress symptoms. White family members experienced a greater reduction in NEST scores compared with Black family members at day 3 (estimated mean difference, -12.5 points; 95% CI, -18.9 to -6.1 points; P < .001 vs estimated mean difference, -0.3 points; 95% CI, -9.3 to 8.8 points; P = .96) and day 7 (estimated mean difference, -9.5 points; 95% CI, -16.1 to -3.0 points; P = .005 vs estimated mean difference, -1.4 points; 95% CI, -10.7 to 7.8; P = .76). Conclusions and Relevance: In this study of ICU patients and family members, a primary palliative care intervention using a mobile application reduced unmet palliative care needs compared with usual care without an effect on psychological distress symptoms at 3 months; there was a greater intervention effect among White family members compared with Black family members. These findings suggest that a mobile application-based intervention is a promising primary palliative care intervention for ICU clinicians that directly addresses the limited supply of palliative care specialists. Trial Registration: ClinicalTrials.gov Identifier: NCT03506438.

Characteristics, therapies, and outcomes of In-Hospital vs Out-of-Hospital cardiac arrest in patients presenting to cardiac intensive care units: From the critical care Cardiology trials network (CCCTN).

BACKGROUND: Cardiac arrest (CA) is a common reason for admission to the cardiac intensive care unit (CICU), though the relative burden of morbidity, mortality, and resource use between admissions with in-hospital (IH) and out-of-hospital (OH) CA is unknown. We compared characteristics, care patterns, and outcomes of admissions to contemporary CICUs after IHCA or OHCA. METHODS: The Critical Care Cardiology Trials Network is a multicenter network of tertiary CICUs in the US and Canada. Participating centers contributed data from consecutive admissions during 2-month annual snapshots from 2017 to 2021. We analyzed characteristics and outcomes of admissions by IHCA vs OHCA. RESULTS: We analyzed 2,075 admissions across 29 centers (50.3% IHCA, 49.7% OHCA). Admissions with IHCA were older (median 66 vs 62 years), more commonly had coronary disease (38.3% vs 29.7%), atrial fibrillation (26.7% vs 15.6%), and heart failure (36.3% vs 22.1%), and were less commonly comatose on CICU arrival (34.2% vs 71.7%), p < 0.001 for all. IHCA admissions had lower lactate (median 4.3 vs 5.9) but greater utilization of invasive hemodynamics (34.3% vs 23.6%), mechanical circulatory support (28.4% vs 16.8%), and renal replacement therapy (15.5% vs 9.4%); p < 0.001 for all. Comatose IHCA patients underwent targeted temperature management less frequently than OHCA patients (63.3% vs 84.9%, p < 0.001). IHCA admissions had lower unadjusted CICU (30.8% vs 39.0%, p < 0.001) and in-hospital mortality (36.1% vs 44.1%, p < 0.001). CONCLUSION: Despite a greater burden of comorbidities, CICU admissions after IHCA have lower lactate, greater invasive therapy utilization, and lower crude mortality than admissions after OHCA.

Trajectories of Palliative Care Needs in the ICU and Long-Term Psychological Distress Symptoms.

OBJECTIVES: While palliative care needs are assumed to improve during ICU care, few empiric data exist on need trajectories or their impact on long-term outcomes. We aimed to describe trajectories of palliative care needs during ICU care and to determine if changes in needs over 1 week was associated with similar changes in psychological distress symptoms at 3 months. DESIGN: Prospective cohort study. SETTING: Six adult medical and surgical ICUs. PARTICIPANTS: Patients receiving mechanical ventilation for greater than or equal to 2 days and their family members. MEASUREMENTS AND MAIN RESULTS: The primary outcome was the 13-item Needs at the End-of-Life Screening Tool (NEST; total score range 0-130) completed by family members at baseline, 3, and 7 days. The Patient Health Questionnaire-9 (PHQ-9), Generalized Anxiety Disorder-7 (GAD-7), and Post-Traumatic Stress Scale (PTSS) were completed at baseline and 3 months. General linear models were used to estimate differences in distress symptoms by change in need (NEST improvement ≥ 10 points or not). One-hundred fifty-nine family members participated (median age, 54.0 yr [interquartile range (IQR), 44.0-63.0 yr], 125 [78.6%] female, 54 [34.0%] African American). At 7 days, 53 (33%) a serious level of overall need and 35 (22%) ranked greater than or equal to 1 individual need at the highest severity level. NEST scores improved greater than or equal to 10 points in only 47 (30%). Median NEST scores were 22 (IQR, 12-40) at baseline and 19 (IQR, 9-37) at 7 days (change, -2.0; IQR, -11.0 to 5.0; p = 0.12). There were no differences in PHQ-9, GAD-7, or PTSS change scores by change in NEST score (all p > 0.15). CONCLUSIONS: Serious palliative care needs were common and persistent among families during ICU care. Improvement in needs was not associated with less psychological distress at 3 months. Serious needs may be commonly underrecognized in current practice.

HIV-1 protease with 10 lopinavir and darunavir resistance mutations exhibits altered inhibition, structural rearrangements and extreme dynamics.

Antiretroviral drug resistance is a therapeutic obstacle for people with HIV. HIV protease inhibitors darunavir and lopinavir are recommended for resistant infections. We characterized a protease mutant (PR10x) derived from a highly resistant clinical isolate including 10 mutations associated with resistance to lopinavir and darunavir. Compared to the wild-type protease, PR10x exhibits ∼3-fold decrease in catalytic efficiency and Ki values of 2-3 orders of magnitude worse for darunavir, lopinavir, and potent investigational inhibitor GRL-519. Crystal structures of the mutant were solved in a ligand-free form and in complex with GRL-519. The structures show altered interactions in the active site, flap-core interface, hydrophobic core, hinge region, and 80s loop compared to the corresponding wild-type protease structures. The ligand-free crystal structure exhibits a highly curled flap conformation which may amplify drug resistance. Molecular dynamics simulations performed for 1 µs on ligand-free dimers showed extremely large fluctuations in the flaps for PR10x compared to equivalent simulations on PR with a single L76V mutation or wild-type protease. This analysis offers insight about the synergistic effects of mutations in highly resistant variants.

Palliative care phenotypes among critically ill patients and family members: intensive care unit prospective cohort study.

OBJECTIVE: Because the heterogeneity of patients in intensive care units (ICUs) and family members represents a challenge to palliative care delivery, we aimed to determine if distinct phenotypes of palliative care needs exist. METHODS: Prospective cohort study conducted among family members of adult patients undergoing mechanical ventilation in six medical and surgical ICUs. The primary outcome was palliative care need measured by the Needs at the End-of-Life Screening Tool (NEST, range from 0 (no need) to 130 (highest need)) completed 3 days after ICU admission. We also assessed quality of communication, clinician-family relationship and patient centredness of care. Latent class analysis of the NEST's 13 items was used to identify groups with similar patterns of serious palliative care needs. RESULTS: Among 257 family members, latent class analysis yielded a four-class model including complex communication needs (n=26, 10%; median NEST score 68.0), family spiritual and cultural needs (n=21, 8%; 40.0) and patient and family stress needs (n=43, 31%; 31.0), as well as a fourth group with fewer serious needs (n=167, 65%; 14.0). Interclass differences existed in quality of communication (median range 4.0-10.0, p<0.001), favourable clinician-family relationship (range 34.6%-98.2%, p<0.001) and both the patient centredness of care Eliciting Concerns (median range 4.0-5.0, p<0.001) and Decision-Making (median range 2.3-4.5, p<0.001) scales. CONCLUSIONS: Four novel phenotypes of palliative care need were identified among ICU family members with distinct differences in the severity of needs and perceived quality of the clinician-family interaction. Knowledge of need class may help to inform the development of more person-centred models of ICU-based palliative care.

Assessment of Clinical Palliative Care Trigger Status vs Actual Needs Among Critically Ill Patients and Their Family Members.

Importance: Palliative care consultations in intensive care units (ICUs) are increasingly prompted by clinical characteristics associated with mortality or resource utilization. However, it is not known whether these triggers reflect actual palliative care needs. Objective: To compare unmet needs by clinical palliative care trigger status (present vs absent). Design, Setting, and Participants: This prospective cohort study was conducted in 6 adult medical and surgical ICUs in academic and community hospitals in North Carolina between January 2019 and September 2020. Participants were consecutive patients receiving mechanical ventilation and their family members. Exposure: Presence of any of 9 common clinical palliative care triggers. Main Outcomes and Measures: The primary outcome was the Needs at the End-of-Life Screening Tool (NEST) score (range, 0-130, with higher scores reflecting greater need), which was completed after 3 days of ICU care. Trigger status performance in identifying serious need (NEST score ≥30) was assessed using sensitivity, specificity, positive and negative likelihood ratios, and C statistics. Results: Surveys were completed by 257 of 360 family members of patients (71.4% of the potentially eligible patient-family member dyads approached) with a median age of 54.0 years (IQR, 44-62 years); 197 family members (76.7%) were female, and 83 (32.3%) were Black. The median age of patients was 58.0 years (IQR, 46-68 years); 126 patients (49.0%) were female, and 88 (33.5%) were Black. There was no difference in median NEST score between participants with a trigger present (45%) and those with a trigger absent (55%) (21.0; IQR, 12.0-37.0 vs 22.5; IQR, 12.0-39.0; P = .52). Trigger presence was associated with poor sensitivity (45%; 95% CI, 34%-55%), specificity (55%; 95% CI, 48%-63%), positive likelihood ratio (1.0; 95% CI, 0.7-1.3), negative likelihood ratio (1.0; 95% CI, 0.8-1.2), and C statistic (0.50; 95% CI, 0.44-0.57). Conclusions and Relevance: In this cohort study, clinical palliative care trigger status was not associated with palliative care needs and no better than chance at identifying the most serious needs, which raises questions about an increasingly common clinical practice. Focusing care delivery on directly measured needs may represent a more person-centered alternative.

Effect of a Hospital and Postdischarge Quality Improvement Intervention on Clinical Outcomes and Quality of Care for Patients With Heart Failure With Reduced Ejection Fraction: The CONNECT-HF Randomized Clinical Trial.

Importance: Adoption of guideline-directed medical therapy for patients with heart failure is variable. Interventions to improve guideline-directed medical therapy have failed to consistently achieve target metrics, and limited data exist to inform efforts to improve heart failure quality of care. Objective: To evaluate the effect of a hospital and postdischarge quality improvement intervention compared with usual care on heart failure outcomes and care. Design, Setting, and Participants: This cluster randomized clinical trial was conducted at 161 US hospitals and included 5647 patients (2675 intervention vs 2972 usual care) followed up after a hospital discharge for acute heart failure with reduced ejection fraction (HFrEF). The trial was performed from 2017 to 2020, and the date of final follow-up was August 31, 2020. Interventions: Hospitals (n = 82) randomized to a hospital and postdischarge quality improvement intervention received regular education of clinicians by a trained group of heart failure and quality improvement experts and audit and feedback on heart failure process measures (eg, use of guideline-directed medical therapy for HFrEF) and outcomes. Hospitals (n = 79) randomized to usual care received access to a generalized heart failure education website. Main Outcomes and Measures: The coprimary outcomes were a composite of first heart failure rehospitalization or all-cause mortality and change in an opportunity-based composite score for heart failure quality (percentage of recommendations followed). Results: Among 5647 patients (mean age, 63 years; 33% women; 38% Black; 87% chronic heart failure; 49% recent heart failure hospitalization), vital status was known for 5636 (99.8%). Heart failure rehospitalization or all-cause mortality occurred in 38.6% in the intervention group vs 39.2% in usual care (adjusted hazard ratio, 0.92 [95% CI, 0.81 to 1.05). The baseline quality-of-care score was 42.1% vs 45.5%, respectively, and the change from baseline to follow-up was 2.3% vs -1.0% (difference, 3.3% [95% CI, -0.8% to 7.3%]), with no significant difference between the 2 groups in the odds of achieving a higher composite quality score at last follow-up (adjusted odds ratio, 1.06 [95% CI, 0.93 to 1.21]). Conclusions and Relevance: Among patients with HFrEF in hospitals randomized to a hospital and postdischarge quality improvement intervention vs usual care, there was no significant difference in time to first heart failure rehospitalization or death, or in change in a composite heart failure quality-of-care score. Trial Registration: ClinicalTrials.gov Identifier: NCT03035474.

HIV Protease: Historical Perspective and Current Research.

The retroviral protease of human immunodeficiency virus (HIV) is an excellent target for antiviral inhibitors for treating HIV/AIDS. Despite the efficacy of therapy, current efforts to control the disease are undermined by the growing threat posed by drug resistance. This review covers the historical background of studies on the structure and function of HIV protease, the subsequent development of antiviral inhibitors, and recent studies on drug-resistant protease variants. We highlight the important contributions of Dr. Stephen Oroszlan to fundamental knowledge about the function of the HIV protease and other retroviral proteases. These studies, along with those of his colleagues, laid the foundations for the design of clinical inhibitors of HIV protease. The drug-resistant protease variants also provide an excellent model for investigating the molecular mechanisms and evolution of resistance.

Improving racial disparities in unmet palliative care needs among intensive care unit family members with a needs-targeted app intervention: The ICUconnect randomized clinical trial.

INTRODUCTION: The technologies used to treat the millions who receive care in intensive care unit (ICUs) each year have steadily advanced. However, the quality of ICU-based communication has remained suboptimal, particularly concerning for Black patients and their family members. Therefore we developed a mobile app intervention for ICU clinicians and family members called ICUconnect that assists with delivering need-based care. OBJECTIVE: To describe the methods and early experiences of a clustered randomized clinical trial (RCT) being conducted to compare ICUconnect vs. usual care. METHODS AND ANALYSIS: The goal of this two-arm, parallel group clustered RCT is to determine the clinical impact of the ICUconnect intervention in improving outcomes overall and for each racial subgroup on reducing racial disparities in core palliative care outcomes over a 3-month follow up period. ICU attending physicians are randomized to either ICUconnect or usual care, with outcomes obtained from family members of ICU patients. The primary outcome is change in unmet palliative care needs measured by the NEST instrument between baseline and 3 days post-randomization. Secondary outcomes include goal concordance of care and interpersonal processes of care at 3 days post-randomization; length of stay; as well as symptoms of depression, anxiety, and post-traumatic stress disorder at 3 months post-randomization. We will use hierarchical linear models to compare outcomes between the ICUconnect and usual care arms within all participants and assess for differential intervention effects in Blacks and Whites by adding a patient-race interaction term. We hypothesize that both compared to usual care as well as among Blacks compared to Whites, ICUconnect will reduce unmet palliative care needs, psychological distress and healthcare resource utilization while improving goal concordance and interpersonal processes of care. In this manuscript, we also describe steps taken to adapt the ICUconnect intervention to the COVID-19 pandemic healthcare setting. ENROLLMENT STATUS: A total of 36 (90%) of 40 ICU physicians have been randomized and 83 (52%) of 160 patient-family dyads have been enrolled to date. Enrollment will continue until the end of 2021.

Evolution of drug resistance in HIV protease.

BACKGROUND: Drug resistance is a critical problem limiting effective antiviral therapy for HIV/AIDS. Computational techniques for predicting drug resistance profiles from genomic data can accelerate the appropriate choice of therapy. These techniques can also be used to identify protease mutants for experimental studies of resistance and thereby assist in the development of next-generation therapies. Few studies, however, have assessed the evolution of resistance from genotype-phenotype data. RESULTS: The machine learning produced highly accurate and robust classification of resistance to HIV protease inhibitors. Genotype data were mapped to the enzyme structure and encoded using Delaunay triangulation. Estimates of evolutionary relationships, based on this encoding, and using Minimum Spanning Trees, showed clusters of mutations that closely resemble the wild type. These clusters appear to evolve uniquely to more resistant phenotypes. CONCLUSIONS: Using the triangulation metric and spanning trees results in paths that are consistent with evolutionary theory. The majority of the paths show bifurcation, namely they switch once from non-resistant to resistant or from resistant to non-resistant. Paths that lose resistance almost uniformly have far lower levels of resistance than those which either gain resistance or are stable. This strongly suggests that selection for stability in the face of a rapid rate of mutation is as important as selection for resistance in retroviral systems.

Machine learning methods accurately predict host specificity of coronaviruses based on spike sequences alone.

Coronaviruses infect many animals, including humans, due to interspecies transmission. Three of the known human coronaviruses: MERS, SARS-CoV-1, and SARS-CoV-2, the pathogen for the COVID-19 pandemic, cause severe disease. Improved methods to predict host specificity of coronaviruses will be valuable for identifying and controlling future outbreaks. The coronavirus S protein plays a key role in host specificity by attaching the virus to receptors on the cell membrane. We analyzed 1238 spike sequences for their host specificity. Spike sequences readily segregate in t-SNE embeddings into clusters of similar hosts and/or virus species. Machine learning with SVM, Logistic Regression, Decision Tree, Random Forest gave high average accuracies, F1 scores, sensitivities and specificities of 0.95-0.99. Importantly, sites identified by Decision Tree correspond to protein regions with known biological importance. These results demonstrate that spike sequences alone can be used to predict host specificity.

Highly drug-resistant HIV-1 protease reveals decreased intra-subunit interactions due to clusters of mutations.

Drug-resistance is a serious problem for treatment of the HIV/AIDS pandemic. Potent clinical inhibitors of HIV-1 protease show several orders of magnitude worse inhibition of highly drug-resistant variants. Hence, the structure and enzyme activities were analyzed for HIV protease mutant HIV-1 protease (EC 3.4.23.16) (PR) with 22 mutations (PRS5B) from a clinical isolate that was selected by machine learning to represent high-level drug-resistance. PRS5B has 22 mutations including only one (I84V) in the inhibitor binding site; however, clinical inhibitors had poor inhibition of PRS5B activity with kinetic inhibition value (Ki ) values of 4-1000 nm or 18- to 8000-fold worse than for wild-type PR. High-resolution crystal structures of PRS5B complexes with the best inhibitors, amprenavir (APV) and darunavir (DRV) (Ki ~ 4 nm), revealed only minor changes in protease-inhibitor interactions. Instead, two distinct clusters of mutations in distal regions induce coordinated conformational changes that decrease favorable internal interactions across the entire protein subunit. The largest structural rearrangements are described and compared to other characterized resistant mutants. In the protease hinge region, the N83D mutation eliminates a hydrogen bond connecting the hinge and core of the protease and increases disorder compared to highly resistant mutants PR with 17 mutations and PR with 20 mutations with similar hinge mutations. In a distal ß-sheet, mutations G73T and A71V coordinate with accessory mutations to bring about shifts that propagate throughout the subunit. Molecular dynamics simulations of ligand-free dimers show differences consistent with loss of interactions in mutant compared to wild-type PR. Clusters of mutations exhibit both coordinated and antagonistic effects, suggesting PRS5B may represent an intermediate stage in the evolution of more highly resistant variants. DATABASES: Structural data are available in Protein Data Bank under the accession codes 6P9A and 6P9B for PRS5B/DRV and PRS5B/APV, respectively.

Cardiac Arrest in the Setting of Diffuse Coronary Ectasia: Perspectives on a Unique Ischemic Insult.

A 69-year-old man with a history of coronary artery ectasia, potentially resulting from an underlying heritable connective tissue disorder, presented with ventricular fibrillation. Despite medical management of ischemia, he developed recurrent ventricular tachycardia with poor neurological recovery. We highlight challenges in the management of coronary artery ectasia. (Level of Difficulty: Beginner.).

Care Optimization Through Patient and Hospital Engagement Clinical Trial for Heart Failure: Rationale and design of CONNECT-HF.

Many therapies have been shown to improve outcomes for patients with heart failure (HF) in controlled settings, but there are limited data available to inform best practices for hospital and post-discharge quality improvement initiatives. The CONNECT-HF study is a prospective, cluster-randomized trial of 161 hospitals in the United States with a 2×2 factorial design. The study is designed to assess the effect of a hospital and post-discharge quality improvement intervention compared with usual care (primary objective) on HF outcomes and quality-of-care, as well as to evaluate the effect of hospitals implementing a patient-level digital intervention compared with usual care (secondary objective). The hospital and post-discharge intervention includes audit and feedback on HF clinical process measures and outcomes for patients with HF with reduced ejection fraction (HFrEF) paired with education to sites and clinicians by a trained, nationally representative group of HF and quality improvement experts. The patient-level digital intervention is an optional ancillary study and includes a mobile application and behavioral tools that are intended to facilitate improved use of guideline-directed recommendations for self-monitoring and self-management of activity and medications for HFrEF. The effects of the interventions will be measured through an opportunity-based composite score on quality and time-to-first HF readmission or death among patients with HFrEF who present to study hospitals with acute HF and who consent to participate. The CONNECT-HF study is evaluating approaches for implementing HF guideline recommendations into practice and is one of the largest HF implementation science trials performed to date.

Highly Drug-Resistant HIV-1 Protease Mutant PRS17 Shows Enhanced Binding to Substrate Analogues.

We report the structural analysis of highly drug-resistant human immunodeficiency virus protease (PR) variant PRS17, rationally selected by machine learning, in complex with substrate analogues. Crystal structures were solved of inhibitor-free inactive PRS17-D25N, wild-type PR/CA-p2 complex, and PRS17 in complex with substrate analogues, CA-p2 and p2-NC. Peptide analogues p2-NC and CA-p2 exhibit inhibition constants of 514 and 22 nM, respectively, for PRS17 or approximately 3-fold better than for PR. CA-p2 is a better inhibitor of PRS17 than are clinical inhibitors (K i = 50-8390 nM) except for amprenavir (K i = 11 nM). G48V resistance mutation induces curled flap tips in PRS17-D25N structure. The inner P2-P2' residues of substrate analogues in PRS17 complexes maintain similar conformations to those of wild-type complex, while significant conformational changes are observed in the peripheral residues P3, P4' of CA-p2 and P3, P4, and P3' of p2-NC. The loss of ß-branched side chain by V82S mutation initiates a shift in 80's loop and reshapes the S3/S3' subsite, which enhances substrate binding with new hydrogen bonds and van der Waals interactions that are absent in the wild-type structures. The steric hindrance caused by G48V mutation in the flap of PRS17 contributes to altered binding interactions of P3 Arg, P4' norleucine of CA-p2, and P4 and P3' of p2-NC with the addition of new hydrogen bonds and van der Waals contacts. The enhanced interaction of PRS17 with substrate analogues agrees with their relative inhibition, suggesting that this mutant improves substrate binding while decreasing affinity for clinical inhibitors.

Structural studies of antiviral inhibitor with HIV-1 protease bearing drug resistant substitutions of V32I, I47V and V82I.

HIV-1 protease inhibitors are effective in HIV/AIDS therapy, although drug resistance is a severe problem. This study examines the effects of four investigational inhibitors against HIV-1 protease with drug resistant mutations of V32I, I47V and V82I (PRTri) that model the inhibitor-binding site of HIV-2 protease. These inhibitors contain diverse chemical modifications on the darunavir scaffold and form new interactions with wild type protease, however, the measured inhibition constants for PRTri mutant range from 17 to 40 nM or significantly worse than picomolar values reported for wild type enzyme. The X-ray crystal structure of PRTri mutant in complex with inhibitor 1 at 1.5 Šresolution shows minor changes in interactions with inhibitor compared with the corresponding wild type PR complex. Instead, the basic amine at P2 of inhibitor together with mutation V82I induces two alternate conformations for the side chain of Arg8 with new interactions with inhibitor and Leu10. Hence, inhibition is influenced by small coordinated changes in hydrophobic interactions.

Rivaroxaban in Acute Coronary Syndromes: We Have a Compass and an Atlas, But Where Are We Headed?

See Article by Gibson et al.

Frequency, Regional Variation, and Predictors of Undetermined Cause of Death in Cardiometabolic Clinical Trials: A Pooled Analysis of 9259 Deaths in 9 Trials.

BACKGROUND: Modern cardiometabolic clinical trials often include cardiovascular death as a component of a composite primary outcome, requiring central adjudication by a clinical events committee to classify cause of death. However, sometimes the cause of death cannot be determined from available data. The US Food and Drug Administration has indicated that this circumstance should occur only rarely, but its prevalence has not been formally assessed. METHODS: Data from 9 global clinical trials (2009-2017) with long-term follow-up and blinded, centrally adjudicated cause of death were used to calculate the proportion of deaths attributed to cardiovascular, noncardiovascular, or undetermined causes by therapeutic area (diabetes mellitus/pre-diabetes mellitus, stable atherosclerosis, atrial fibrillation, and acute coronary syndrome), region of patient enrollment, and year of trial manuscript publication. Patient- and trial-level variables associated with undetermined cause of death were identified using a logistic model. RESULTS: Across 127 049 enrolled participants from 9 trials, there were 9259 centrally adjudicated deaths: 5012 (54.1%) attributable to cardiovascular causes, 2800 (30.2%) attributable to noncardiovascular causes, and 1447 (15.6%) attributable to undetermined causes. There was variability in the proportion of deaths ascribed to undetermined causes by trial therapeutic area, region of enrollment, and year of trial manuscript publication. On multivariable analysis, acute coronary syndrome or atrial fibrillation trial (versus atherosclerotic vascular disease or diabetes mellitus/pre-diabetes mellitus), longer time from enrollment to death, more recent trial manuscript publication year, enrollment in North America (versus Western Europe), female sex, and older age were associated with greater likelihood of death of undetermined cause. CONCLUSIONS: In 9 cardiometabolic clinical trials with long-term follow-up, approximately 16% of deaths had undetermined causes. This provides a baseline for quality assessment of clinical trials and informs operational efforts to potentially reduce the frequency of undetermined deaths in future clinical research.

Drug Resistance Mutation L76V Alters Nonpolar Interactions at the Flap-Core Interface of HIV-1 Protease.

Four HIV-1 protease (PR) inhibitors, clinical inhibitors lopinavir and tipranavir, and two investigational compounds 4 and 5, were studied for their effect on the structure and activity of PR with drug-resistant mutation L76V (PRL76V). Compound 5 exhibited the best K i value of 1.9 nM for PRL76V, whereas the other three inhibitors had K i values of 4.5-7.6 nM, 2-3 orders of magnitude worse than for wild-type enzymes. Crystal structures showed only minor differences in interactions of inhibitors with PRL76V compared to wild-type complexes. The shorter side chain of Val76 in the mutant lost hydrophobic interactions with Lys45 and Ile47 in the flap, and with Asp30 and Thr74 in the protein core, consistent with decreased stability. Inhibitors forming additional polar interactions with the flaps or dimer interface of PRL76V were unable to compensate for the decrease in internal hydrophobic contacts. These structures provide insights for inhibitor design.