The RRM of the kRNA-editing protein TbRGG2 uses multiple surfaces to bind and remodel RNA.

Kinetoplastid RNA (kRNA) editing takes place in the mitochondria of kinetoplastid protists and creates translatable mRNAs by uridine insertion/deletion. Extensively edited (pan-edited) transcripts contain quadruplex forming guanine stretches, which must be remodeled to promote uridine insertion/deletion. Here we show that the RRM domain of the essential kRNA-editing factor TbRGG2 binds poly(G) and poly(U) RNA and can unfold both. A region C-terminal to the RRM mediates TbRGG2 dimerization, enhancing RNA binding. A RRM-U4 RNA structure reveals a unique RNA-binding mechanism in which the two RRMs of the dimer employ aromatic residues outside the canonical RRM RNA-binding motifs to encase and wrench open the RNA, while backbone atoms specify the uridine bases. Notably, poly(G) RNA is bound via a different binding surface. Thus, these data indicate that TbRGG2 RRM can bind and remodel several RNA substrates suggesting how it might play multiple roles in the kRNA editing process.

Alirocumab in Acute Myocardial Infarction: Results From the Virginia Commonwealth University Alirocumab Response Trial (VCU-AlirocRT).

Alirocumab improves outcomes in patients with a history of recent acute coronary syndrome, but treatment acutely at the time of myocardial infarction is untested. We present the results of a randomized, placebo-controlled, double-blinded pilot study of alirocumab treatment at the time of non-ST elevation MI (NSTEMI). Twenty patients with type 1 NSTEMI and low-density lipoprotein cholesterol (LDL-C) >70 mg/dL despite high intensity statin therapy were randomized 1:1 to one dose of alirocumab 150 mg subcutaneously or placebo within 24 hours of presentation. LDL-C and inflammatory biomarkers-including C-reactive protein-were obtained at baseline, 72 hours, and 14 days. Median (interquartile range) and number (%) were: age 59 (49, 65) years, 7 (35%) men, 16 (80%) black; baseline characteristics were similar between groups. Alirocumab significantly reduced LDL-C from baseline to 14 days by 64 mg/dL (-96, -47) compared with placebo [+1 mg/dL (-25, +16)] (primary endpoint). There were no significant between-group differences in C-reactive protein changes at any time point (all P > 0.2) or serious adverse events attributable to the study treatment. In conclusion, alirocumab administration at the time of NSTEMI significantly reduced LDL-C levels at 14 days, was safe, and had neutral effects on inflammatory biomarkers. Further studies are warranted to explore the effects on clinical outcomes.

In Vitro Hepatic Clearance Evaluations of Per- and Polyfluoroalkyl Substances (PFAS) across Multiple Structural Categories.

Toxicokinetic (TK) assays and in vitro-in vivo extrapolation (IVIVE) models are New Approach Methods (NAMs) used to translate in vitro points of departure to exposure estimates required to reach equivalent blood concentrations. Per- and polyfluoroalkyl substances (PFAS) are a large chemical class with wide-ranging industrial applications for which only limited toxicity data are available for human health evaluation. To address the lack of TK data, a pooled primary human hepatocyte suspension model was used with targeted liquid chromatography-mass spectrometry to investigate substrate depletion for 54 PFAS. A median value of 4.52 µL/(min x million cells) was observed across those that showed significant clearance, with 35 displaying no substrate depletion. Bayesian modeling propagated uncertainty around clearance values for use in IVIVE models. Structural evaluations showed the fluorotelomer carboxylic acids were the only PFAS carboxylates showing appreciable clearance, and per- and polyfluorosulfonamides were more readily metabolized than other PFAS sulfonates. Biotransformation product prediction, using the chemical transformation simulator, suggested hydrolysis of PFAS sulfonamides to more stable sulfonic acids, which is an important consideration for exposure modeling. This effort greatly expands the PFAS in vitro toxicokinetic dataset, enabling refined TK modeling, in silico tool development, and NAM-based human health evaluations across this important set of emerging contaminants.

Dose Response, Dosimetric, and Metabolic Evaluations of Replacement PFAS Perfluoro-(2,5,8-trimethyl-3,6,9-trioxadodecanoic) Acid (HFPO-TeA).

Few studies are available on the environmental and toxicological effects of perfluoroalkyl ether carboxylic acids (PFECAs), such as GenX, which are replacing legacy PFAS in manufacturing processes. To collect initial data on the toxicity and toxicokinetics of a longer-chain PFECA, male and female Sprague Dawley rats were exposed to perfluoro-(2,5,8-trimethyl-3,6,9-trioxadodecanoic) acid (HFPO-TeA) by oral gavage for five days over multiple dose levels (0.3-335.2 mg/kg/day). Clinically, we observed mortality at doses >17 mg/kg/day and body weight changes at doses ≤17 mg/kg/day. For the 17 mg/kg/day dose level, T3 and T4 thyroid hormone concentrations were significantly decreased (p < 0.05) from controls and HFPO-TeA plasma concentrations were significantly different between sexes. Non-targeted analysis of plasma and in vitro hepatocyte assay extractions revealed the presence of another GenX oligomer, perfluoro-(2,5-dimethyl-3,6-dioxanonanoic) acid (HFPO-TA). In vitro to in vivo extrapolation (IVIVE) parameterized with in vitro toxicokinetic data predicted steady-state blood concentrations that were within seven-fold of those observed in the in vivo study, demonstrating reasonable predictivity. The evidence of thyroid hormone dysregulation, sex-based differences in clinical results and dosimetry, and IVIVE predictions presented here suggest that the replacement PFECA HFPO-TeA induces a complex and toxic exposure response in rodents.

QT Prolongation and In-Hospital Ventricular Arrhythmic Complications in Patients With Apical Ballooning Takotsubo Syndrome.

BACKGROUND: Takotsubo syndrome is associated with life threatening arrhythmias, and the apical ballooning pattern is characterized by a peculiar QT prolongation and particularly high-risk of arrhythmias. OBJECTIVES: The aim of the study was to determine the association of QT interval on electrocardiogram for ventricular arrhythmic complications in patients with apical ballooning Takotsubo syndrome in a diverse population at a large urban hospital in the U.S. METHODS: We reviewed 105 cases of apical ballooning Takotsubo syndrome in patients admitted between 2011 and 2017. Two cardiologists reviewed the electrocardiograms to measure QT interval, adjusted for rate using the Fridericia formula (QTCF), and ventricular arrhythmic complications during the hospitalization. Data are reported as median and interquartile range or number and percentage. RESULTS: Of the 105 patients, 86 (82%) were female, and 34 (32%) were self-reported Black or African American. The mean age was 65 years (range: 58-72 years). Left ventricular ejection fraction was 25% (range: 25%-35%). Heart rate was 101 beats/min (range: 83-121 beats/min). Ten (11%) patients experienced a ventricular arrhythmic complication and had significantly longer QTCF (470 [range: 422-543] milliseconds) than did those without complications (417 [range: 383-456] milliseconds, P = 0.031). The area under the curve for QTCF was 0.708 (95% CI: 0.536-0.880; P = 0.031). Twenty-eight (27%) patients had a QTCF ≥460 milliseconds and significantly more arrhythmic complications (21% vs 5%, odds ratio 4.997 [95% CI: 1.288-19.237], P = 0.021). QTCF was an independent predictor of ventricular arrhythmias: odds ratio 1.090 for each 10-millisecond increase in QTCF (95% CI: 1.004-1.183; P = 0.040, corrected for sex). CONCLUSIONS: In a diverse population of patients with apical ballooning Takotsubo syndrome admitted to a large urban hospital in the United States, QTCF at admission ≥460 milliseconds identifies patients at high risk for in-hospital arrhythmic complications. Further studies are needed to determine strategies aimed at shortening QT interval to potentially prevent life-threatening arrhythmic events.

Comparison of Cardiorespiratory Fitness in Black or African American Versus Caucasian Patients With Heart Failure.

PURPOSE: Cardiopulmonary exercise testing (CPX) is a well-established assessment with important insight into prognosis and therapeutic efficacy in patients with heart failure (HF). Prior studies have identified several clinical differences between Black or African American (B-AA) and Caucasian patients with HF. Differences in key CPX responses between these two groups require further investigation. METHODS: Using a database consisting of subjects with symptomatic HF who had undergone CPX for inclusion in various prospective randomized clinical trials, we identified 198 (n = 94 [47%] B-AA; n = 105 [53%] Caucasian) patients with a qualifying baseline CPX. Significant univariate predictors of peak oxygen uptake (V˙o2peak) were included in a multivariate linear regression model. RESULTS: When compared with Caucasian patients, B-AA were younger (mean ± SD = 54.8 ± 10.0 vs 57.9 ± 9.6 yr, P = .03), had higher C-reactive protein (CRP) (median [IQR] = 4.9 [2.3, 8.8] vs 1.9 [0.6, 5.5] mg/L, P < .0001), lower hemoglobin (13.0 ± 1.8 vs 13.8 ± 1.6 g/dL, P = .003), and lower left ventricular ejection fraction (LVEF) (40 [32, 51] vs 53 [43, 59]%, P < .00010). During CPX, B-AA patients also had lower V˙o2peak (14.6 ± 3.9 vs 17.6 ± 4.8 mL·kg-1·min-1, P < .0001). No differences were observed between B-AA and Caucasian in the minute ventilation/carbon dioxide production (V˙e/V˙co2) slope (P = .14). The difference in V˙o2peak between B-AA and Caucasian was largely attenuated after adjusting for age, body mass index, CRP, N-terminal pro-brain natriuretic peptide, hemoglobin, LVEF, and peak HR (14.1: 95% CI, 13.2-14.9 vs 15.6: 95% CI, 14.4-16.8 mL·kg-1·min-1, P = .053). CONCLUSIONS: Directly measured V˙o2peak was significantly lower in B-AA than in Caucasians with HF. This is largely explained by differences in clinical characteristics, whereas no significant differences were observed in the V˙e/V˙co2 slope.

Optimal Stent Design for High Bleeding Risk Patients: Evidence From a Network Meta-Analysis.

OBJECTIVE: To determine the best stent design for high bleeding risk (HBR) patients. BACKGROUND: Polymer-free (PF) drug eluting stent (DES) devices have a proven benefit over bare-metal stent (BMS) devices in previous trials. It is unknown, however, whether polymer-based (PB)-DES devices are as safe as PF-DES devices. METHODS: A network meta-analysis including all randomized controlled trials (RCTs) that compared different stent technology in HBR patients with a 1-month course of dual-antiplatelet therapy (DAPT) was performed. The main efficacy outcome was major adverse cardiac event (MACE) rate, defined as the composite of all-cause mortality, myocardial infarction (MI), and target-lesion revascularization (TLR). Secondary efficacy events included all-cause and cardiac mortality, MI, stroke, TLR, and target-vessel revascularization (TVR). Safety outcomes included all bleeding, major bleeding, and stent thrombosis (ST). RESULTS: A total of 4 RCTs with 6456 patients were included. PF-DES and PB-DES yielded a reduced rate of MACE, MI, TLR, and TVR events compared with BMS (all P<.05). ST events were reduced in PB-DES compared with BMS (P=.01). No differences were found in all-cause death, cardiac death, or stroke events in PF-DES and PB-DES compared with BMS. Furthermore, no differences were found between PF-DES and PB-DES regarding any of the outcomes. CONCLUSION: DES devices were associated with lower MACE and TVR rates compared with BMS, whereas there were no statistical differences in other efficacy endpoints. Also, PB-DES were associated with fewer ST events compared with BMS. There were no statistical differences between PB-DES and PF-DES with regard to any of the endpoints.

Clinical features and outcomes between African American and Caucasian patients with Takotsubo Syndrome.

BACKGROUND: Takotsubo syndrome (TS) is an acute, reversible form of heart failure, often mimicking an acute coronary syndrome (ACS). Data regarding racial differences in TS are inconsistent. The aim is to assess clinical features associated with unfavorable in-hospital outcomes between African American (AA) and Caucasian (CAU) patients. METHODS: A retrospective electronic health record query identified 44 AA patients and 110 CAU patients with a diagnosis of TS. Our primary outcome was a composite of death, stroke, and cardiogenic shock during hospitalization. Variables associated with an increased risk of the primary composite outcomes were included in a logistic regression model. RESULTS: Compared to CAU patients, AA patients were a more comorbid population, and presented a higher prevalence of history of illicit drug use (27.3% vs. 13.6% P=0.044). There were no significant differences regarding in-hospital complication rates between AA and CAU patients. In the logistic regression model, infection was associated with greater risk of developing the primary outcome in AA patients (OR=7.26 [95% CI 1.22-43.17], P=0.029), whereas angina was a protective factor (OR=0.11 [95% CI 0.02-0.65], P=0.015). In CAU patients, severely depressed ejection fraction and worse peak creatinine during hospitalization increased risk of developing the primary outcome (OR=5.88 95% CI [2.01-17.17], P<0.001 and OR=1.64 [95% CI 1.15-2.58], P=0.031, respectively). Meanwhile, emotional stressors were protective (OR=0.16 [95% CI 0.03-0.88], P=0.004). CONCLUSIONS: Despite experiencing the same rate of in-hospital complications, the clinical profiles of AA patients are distinct from CAU patients admitted for TS, and clinical variables correlated with worse in-hospital outcomes also differ by race.

Determinants of Cardiorespiratory Fitness in Patients with Heart Failure Across a Wide Range of Ejection Fractions.

Impaired cardiorespiratory fitness (CRF) in heart failure (HF) is influenced by a complex array of cardiac and extracardiac factors. The study aimed to identify clinical determinants of CRF measured as peak oxygen consumption (peak VO2) in HF patients, and to determine a peak VO2 prediction model using regression equations. Retrospective analysis of 200 HF patients who completed treadmill cardiopulmonary exercise testing and underwent Doppler echocardiography and/or biomarker analysis on the same day was performed. After univariate linear regression analysis, a multivariate peak VO2 prediction model was developed using significant variables in a stepwise linear regression analysis. In subjects with repeated testing, Pearson's correlation was used to assess correlations between measured and predicted change in peak VO2 (Δpeak VO2) over time. Mean age was 57 years, with 55% being male. Stepwise linear regression was used to generate a weighted model for peak VO2: 30.895 + (-0.112•age[years]) + (0.296•hemoglobin [g/dl]) + (-0.101•E/e'[unit change]) + (-0.202• body mass index [kg/m2]) + (-0.593• N-terminal pro-brain natriuretic peptide [logN pg/ml])) + (-1.349•CRP [log mg/L]). Predicted peak VO2 correlated strongly with measured peak VO2 in HF with reduced ejection fraction and HF with preserved ejection fraction patients (r = +0.63, p <0.001; r = +0.64, p <0.001, respectively). Predicted Δpeak VO2 correlated with measured Δpeak VO2 (r = +0.23, p <0.001). In conclusion, in patients with HF across a wide range of left ventricular ejection fraction, age, systemic inflammation, oxygen carrying capacity, obesity, and elevated filling pressures are the strongest predictors of impaired CRF. The proposed CRF model allows prediction of peak VO2 in HF patients and may be used to estimate peak VO2 changes over time.

C-Reactive Protein and N-Terminal Pro-brain Natriuretic Peptide Levels Correlate With Impaired Cardiorespiratory Fitness in Patients With Heart Failure Across a Wide Range of Ejection Fraction.

Background: Impaired cardiorespiratory fitness (CRF) is a hallmark of heart failure (HF). Serum levels of C-reactive protein (CRP), a systemic inflammatory marker, and of N-terminal pro-brain natriuretic peptide (NT-proBNP), a biomarker of myocardial strain, independently predict adverse outcomes in HF patients. Whether CRP and/or NT-proBNP also predict the degree of CRF impairment in HF patients across a wide range of ejection fraction is not yet established. Methods: Using retrospective analysis, 200 patients with symptomatic HF who completed one or more treadmill cardiopulmonary exercise tests (CPX) using a symptom-limited ramp protocol and had paired measurements of serum high-sensitivity CRP and NT-proBNP on the same day were evaluated. Univariate and multivariate correlations were evaluated with linear regression after logarithmic transformation of CRP (log10) and NT-proBNP (logN). Results: Mean age of patients was 57 ± 10 years and 55% were male. Median CRP levels were 3.7 [1.5-9.0] mg/L, and NT-proBNP levels were 377 [106-1,464] pg/ml, respectively. Mean peak oxygen consumption (peak VO2) was 16 ± 4 mlO2•kg-1•min-1. CRP levels significantly correlated with peakVO2 in all patients (R = -0.350, p < 0.001) and also separately in the subgroup of patients with reduced left ventricular ejection fraction (LVEF) (HFrEF, N = 109) (R = -0.282, p < 0.001) and in those with preserved EF (HFpEF, N = 57) (R = -0.459, p < 0.001). NT-proBNP levels also significantly correlated with peak VO2 in all patients (R = -0.330, p < 0.001) and separately in patients with HFrEF (R = -0.342, p < 0.001) and HFpEF (R = -0.275, p = 0.032). CRP and NT-proBNP did not correlate with each other (R = 0.05, p = 0.426), but independently predicted peak VO2 (R = 0.421, p < 0.001 and p < 0.001, respectively). Conclusions: Biomarkers of inflammation and myocardial strain independently predict peak VO2 in HF patients. Anti-inflammatory therapies and therapies alleviating myocardial strain may independently improve CRF in HF patients across a large spectrum of LVEF.