Disease evolution in systemic juvenile idiopathic arthritis: an international, observational cohort study through JIRcohort

BACKGROUND

Systemic juvenile idiopathic arthritis (systemic JIA) is a severe disease with both systemic and joint inflammation. This study aims to identify predictors of disease evolution within the systemic JIA population enrolled in the Juvenile Inflammatory Rheumatism cohort (JIRcohort).

METHODS

Observational patient cohort study with 201 recruited children from 4 countries (3 European, 1 North Africa) from 2005 until 2019, using retrospectively (2005-2015) and prospectively (2015-2019) routine care collected data.

RESULTS

Sixty-five patients with complete follow-up data for 24 months after first diagnosis were classified as monophasic (n = 23), polyphasic (n = 6) or persistent group (n = 36) corresponding to their evolution (unique flare, recurrent flares, or persistent disease activity respectively). The patients of the persistent group were more likely to have an earlier disease onset, before the age of 6 (OR 2.57, 95%-CI 0.70-9.46), persistence of arthritis at 12-months post-diagnosis (OR 4.45, 95%-CI 0.58-34.20) and higher use of synthetic DMARD (sDMARD, OR 5.28, 95%-CI 1.39-20.01). Other variables like global assessment by physician and by patient and C Reactive Protein levels at 12-months post-diagnosis were assessed but without any predictive value after adjusting for confounding factors.

CONCLUSIONS

Our results suggest that the earlier disease onset, the persistence of arthritis throughout the first year of disease evolution and the need of sDMARD might predict a persistent disease course.

Smartwatch-derived heart rate variability: a head-to-head comparison with the gold standard in cardiovascular disease

Aims

We aimed to investigate the concordance between heart rate variability (HRV) derived from the photoplethysmographic (PPG) signal of a commercially available smartwatch compared with the gold-standard high-resolution electrocardiogram (ECG)-derived HRV in patients with cardiovascular disease.

Methods and results

We prospectively enrolled 104 survivors of acute ST-elevation myocardial infarction, 129 patients after an ischaemic stroke, and 30 controls. All subjects underwent simultaneous recording of a smartwatch (Garmin vivoactive 4; Garmin Ltd, Olathe, KS, USA)-derived PPG signal and a high-resolution (1000 Hz) ECG for 30 min under standardized conditions. HRV measures in time and frequency domain, non-linear measures, as well as deceleration capacity (DC) were calculated according to previously published technologies from both signals. Lin's concordance correlation coefficient (ρc) between smartwatch-derived and ECG-based HRV markers was used as a measure of diagnostic accuracy. A very high concordance within the whole study cohort was observed for the mean heart rate (ρc = 0.9998), standard deviation of the averages of normal-to-normal (NN) intervals in all 5min segments (SDANN; ρc = 0.9617), and very low frequency power (VLF power; ρc = 0.9613). In contrast, detrended fluctuation analysis (DF-α1; ρc = 0.5919) and the square mean root of the sum of squares of adjacent NN-interval differences (rMSSD; ρc = 0.6617) showed only moderate concordance.

Conclusion

Smartwatch-derived HRV provides a practical alternative with excellent accuracy compared with ECG-based HRV for global markers and those characterizing lower frequency components. However, caution is warranted with HRV markers that predominantly assess short-term variability.

pH-dependent structural diversity of profilin allergens determines thermal stability

The family of profilin allergens is a common class of proteins found in plants, viruses and various eukaryotes including mammals. Profilins are characterized by an evolutionary conserved structural fold, which is responsible for their cross-reactive nature of Immunoglobulin E (IgE) antibodies. Despite their high overall structural similarity, they exhibit substantial differences in their biophysical properties, such as thermal and pH stability. To understand the origin of these functional differences of Amb a 8, Art v 4 and Bet v 2, we performed constant pH molecular dynamics simulation in combination with Gaussian accelerated MD simulations. Depending on the respective protonation at different pH levels, we find distinct differences in conformational flexibility, which are consistent with experimentally determined melting temperatures. These variations in flexibility are accompanied by ensemble shifts in the conformational landscape and quantified and localized by residue-wise B-factors and dihedral entropies. These findings strengthen the link between flexibility of profilin allergens and their thermal stability. Thus, our results clearly show the importance of considering protonation dependent conformational ensembles in solution to elucidate biophysical differences between these structurally similar allergens.

Soluble urokinase plasminogen activator receptor predicts survival and hospitalization for heart failure in elective cardiac surgery

Aims

The study investigated the prognostic value of soluble urokinase plasminogen activator receptor (suPAR) patients undergoing cardiac surgery and calculated a simplified biomarker score comprising suPAR, N-terminal pro B-type natriuretic peptide (NT-proBNP) and age.

Methods and results

Biomarkers were assessed in a cohort of 478 patients undergoing elective cardiac surgery. After a median follow-up of 4.2 years a total of 72 (15.1%) patients died. SuPAR, NT-proBNP and age were independent prognosticators of mortality in a multivariable Cox regression model after adjustment for EuroScoreII. We then calculated a simplified biomarker score comprising age, suPAR and NT-proBNP, which had a superior prognostic value compared to EuroScoreII (Harrel's C of 0.76 vs 0.72; P for difference = 0.02). Besides long-term mortality, the biomarker score had an excellent performance predicting one-year mortality and hospitalization due to heart failure.

Conclusion

The biomarker suPAR and NT-proBNP were strongly and independently associated with mortality in patients undergoing cardiac surgery. A simplified biomarker score comprising only 3 variables (age, suPAR and NT-proBNP) performed better than the established EuroScoreII with respect to intermediate and long-term outcome as well as hospitalization due to heart failure. As such, integration of established and upcoming biomarkers in clinical practice may provide improved decision support in cardiac surgery.

Funding Acknowledgement

Type of funding sources: None.

The gender gap in prescription pattern of sodium-glucose cotransporter 2 inhibitors in patients with type 2 diabetes

Background

The major benefit of sodium-glucose cotransporter 2 inhibitors (SGLT2i) in type 2 diabetes mellitus (T2DM) on cardiovascular outcome has been undoubtably proven in several landmark trials and different populations. In consideration of emerging evidence that there are clinically relevant gender-related differences in the course of T2DM and subsequent cardiovascular outcomes, it is unknown if SGLT2i therapy is gender independent utilized in clinical practice. In this regard, real-world data are needed to determine whether there is a gender gap in SGLT2i prescription and if this influences long-term outcome.

Methods

Patients with T2DM admitted to a tertiary academic center between 01/2014 and 04/2020 were identified through a search of electronic health records. Data on antidiabetic therapy was acquired at discharge, and were screened for SGLT2i prescription. Subsequently, the entire cohort was prospectively followed.

Results

In total, 812 patients (median age 70 years, 29.7% female) were included in the present analysis. Only 17.3% of the study population received an SGLT2i. In direct comparison between sexes, females show lower rates of SGLT2i prescription (11,2% vs. 19,8%, p=0.003), despite comparable patient characteristics. Furthermore, males show a significantly higher probability of SGLT2i prescription, illustrated as an adjusted odds ratio of 2.59 (CI 95% 1.29–5.19; p=0.008). During a median follow-up time of 2.3 years, a total of 142 patients died due to cardiovascular causes – corresponding to 103 (18.0%) male and 39 (16.2%) female participants. Females who did not receive a SGLT2i showed higher rates of chronic kidney disease (CKD, 25.2% vs. 7.4%, p=0.039) and greater levels of proBNP (2092 pg/ml (IQR: 738–5279) vs. 825 pg/ml (IQR: 298–2479), p=0.011) as compared to non-SGLT2i females.

Conclusion

Despite clear evidence on the beneficial effect of SGLT2i, the present data suggest a gender-gap in SGLT2i prescription and thus missed potential in female patients. The most common reason for not prescribing a SGLT2i in females was the presence of CKD. However, SGLT2i (i.e. Empagliflozin) are approved to use in individuals with a glomerular filtration rate (GFR) as low as ≥20ml/min, and therefore more awareness has to be raised, that SGLT2i are feasible to prescribe in such vulnerable patients with present cardiovascular comorbidities, to achieve a benefit as shown in several landmark trials. Additionally, more attention is needed to address this gender-gap and ensure that both sexes receive equal attention, in terms of state of the art T2DM therapy to reduce mortality and morbidity.

Funding Acknowledgement

Type of funding sources: None.

Fibroblast growth factor-23 is an independent predictor of hospitalization for heart failure and major cardiovascular adverse events in patients undergoing cardiac surgery

Background

Fibroblast growth factor 23 (FGF-23) plays a crucial role in regulating phosphate and vitamin D metabolism and was proved to be associated with an increased risk for fatal events in individuals suffering from cardiovascular diseases. Since data on the prognostic potential of FGF-23 in individuals undergoing cardiac valve and/or coronary artery bypass graft (CABG) surgery are scarce, the specific objective of this study was to investigate the impact of FGF-23 on postoperative complications, particularly postoperative atrial fibrillation (POAF), hospitalization for heart failure (HHF) and cardiovascular (CV) death in an unselected patient population after cardiac surgery.

Methods

Within the present investigation, patients undergoing elective cardiac valve and/or CABG surgery were prospectively enrolled at the Department of Cardiac Surgery of a medical university. Blood samples were taken prior to surgery and FGF-23 concentrations were subsequently assessed. Patients were followed prospectively until the primary study endpoint (CV death) was reached.

Results

In total, 462 patients were included in the present analysis and followed over a median of 3.9 years. During follow-up 67 (14.5%) patients died. The patients' median age was 70 years (interquartile range [IQR] 60 to 75) and 133 (28.8%) were female. The median FGF-23 level in the entire study population was 1.9 pmol/L (IQR 1.2 to 3.5). Notably, individuals with POAF showed significantly higher FGF-23 levels than patients without (p<0.001). After stratification into tertiles (T) of FGF-23 patients in the highest FGF-23 tertile showed greater rates of HHF, all-cause and CV death. Furthermore, FGF-23 was consistently associated with POAF development showing an adjusted OR for a 1-unit increase in standardized log-transformed biomarker of 1.28 (95% CI: 1.01 to 1.63), along with an adjusted OR of 2.04 (95% CI 1.33 to 3.13, p=0.001) for the pre-defined high risk cut-off value. A steady risk increase for HHF and CV death among ascending FGF-23 tertiles has been noted. Moreover FGF-23 showed strong discriminatory performance (area under the curve [AUC] 0.69, 95% CI 0.61–0.77). Reclassification analysis indicated that the addition of FGF-23 to NT-proBNP provides a significant improvement in risk discrimination (NRI at the event rate: 0.58, 95% CI 0.34–0.81, p-value <0.001; IDI: 0.03, 95% CI 0.01–0.05, p-value= 0.001).

Conclusion

FGF-23 proved to be a strong and independent predictor for POAF, HHF and CV death in individuals undergoing cardiac surgery. Considering an individualized risk assessment, routine preoperative FGF-23 evaluation may improve detection of patients at risk, who require in-depth clinical attention throughout the peri- and postoperative phase after cardiac surgery.

Funding Acknowledgement

Type of funding sources: None.

The impact of left atrial mechanics on adverse events and clinical outcome after cardiac surgery

Objectives

Post-operative atrial fibrillation (POAF) represents a common complication after cardiac surgery that is associated with unfavorable clinical outcome. Identifying patients at risk for POAF is crucial but challenging.

Purpose

This study aimed to investigate the prognostic potential of speckle tracking echocardiography (STE) on POAF and fatal adverse events from a long-term perspective.

Methods

A total of 124 patients undergoing elective cardiac surgery were prospectively enrolled and underwent pre-operative STE. Patients were followed prospectively for the occurrence of POAF within the entire hospitalization and reaching the secondary endpoints cardiovascular (CV) and all-cause mortality.

Results

Within the study population 43.5% (n=53) of enrolled individuals developed POAF. After a median follow-up of 3.9 years, 25 (20.2%) patients died. We observed that patients presenting with POAF had lower global peak atrial longitudinal strain (PALS) values compared to the non-POAF arm (POAF: 14.8% [95% CI: 10.9–17.8] vs. non-POAF: 19.4% [95% CI: 14.8–23.5], p<0.001). Moreover, global PALS was a strong and independent predictor for POAF (adjusted Odds Ratio per 1-SD: 0.37 [95% CI: 0.22–0.65], p<0.001), and independently associated with mortality (adjusted Hazard Ratio per 1-SD: 0.63 [95% CI: 0.40–0.99], p=0.048). CART analysis revealed a cut-off value of <17% global PALS as high-risk for both POAF and mortality.

Conclusion

Global PALS is associated with the development of POAF following surgery in an unselected patient population undergoing CABG and/or valve surgery. Since patients with global PALS <17% face a poor long-term prognosis, routine assessment of global PALS needs to be considered in terms of proper secondary prevention in the era of personalized medicine.

Funding Acknowledgement

Type of funding sources: None.

Grid inhomogeneous solvation theory for cross-solvation in rigid solvents

Grid Inhomogeneous Solvation Theory (GIST) has proven useful to calculate localized thermodynamic properties of water around a solute. Numerous studies have leveraged this information to enhance structure-based binding predictions. We have recently extended GIST toward chloroform as a solvent to allow the prediction of passive membrane permeability. Here, we further generalize the GIST algorithm toward all solvents that can be modeled as rigid molecules. This restriction is inherent to the method and is already present in the inhomogeneous solvation theory. Here, we show that our approach can be applied to various solvent molecules by comparing the results of GIST simulations with thermodynamic integration (TI) calculations and experimental results. Additionally, we analyze and compare a matrix consisting of 100 entries of ten different solvent molecules solvated within each other. We find that the GIST results are highly correlated with TI calculations as well as experiments. For some solvents, we find Pearson correlations of up to 0.99 to the true entropy, while others are affected by the first-order approximation more strongly. The enthalpy-entropy splitting provided by GIST allows us to extend a recently published approach, which estimates higher order entropies by a linear scaling of the first-order entropy, to solvents other than water. Furthermore, we investigate the convergence of GIST in different solvents. We conclude that our extension to GIST reliably calculates localized thermodynamic properties for different solvents and thereby significantly extends the applicability of this widely used method.

Effectiveness of a home telemonitoring program for patients with chronic obstructive pulmonary disease in Germany: Evidence from the first three years

Introduction

Chronic obstructive pulmonary disease (COPD) affects more than 6 million people in Germany. Monitoring the vital parameters of COPD patients remotely through telemonitoring may help doctors and patients prevent and treat acute exacerbations of COPD, improving patients’ quality of life and saving costs for the statutory health insurance system.

Objective

To evaluate the effects from October 2012 until December 2015 of a structured home telemonitoring program implemented by a statutory health insurer in Germany.

Methods

We conducted a retrospective cohort study using administrative data. After building a balanced control group using Entropy Balancing, we calculated difference-in-difference estimators to account for time-invariant heterogeneity. We estimated differences in mortality rates using Cox regression and conducted subgroup and sensitivity analyses to check the robustness of the base case results. We observed each patient in the program for up to 3 years depending on his or her time of enrolment.

Results

Among patients in the telemonitoring cohort, we observed significantly higher inpatient costs due to COPD (€524.2, p<0,05; €434.6, p<0.05) and outpatient costs (102.5, p<0.01; 78.8 p<0.05) during the first two years of the program. Additional cost categories were significantly increased during the first year of telemonitoring. We also observed a significantly higher number of drug prescriptions during all three years of the observation period (2.0500, p < 0.05; 0.7260, p < 0.05; 3.3170, p < 0.01) and a higher number of outpatient contacts during the first two years (0.945, p<0.01, 0.683, p<0.05). Furthermore, we found significantly improved survival rates for participants in the telemonitoring program (HR 0.68, p<0.001).

Conclusion

On one hand, telemonitoring was associated with higher health care expenditures, especially in the first year of the program. For example, we were able to identify a statistically significant increase in inpatient costs due to COPD, outpatient contacts and drug prescriptions among individuals participating in the telemonitoring program. On the other hand, the telemonitoring program was accompanied by a survival benefit, which might be related to higher adherence rates, more intense treatment, or an improved understanding of COPD among these patients.

The age-specific prognostic impact of the platelet-to-lymphocyte ratio on long-term outcome after acute coronary syndrome

Background

Personalized risk stratification within the ageing society after ACS remains scarce. With increasing general life expectancy, easily applicable age-specific strategies for the prediction of fatal adverse events are in urgent need. Increased platelet activity together with inflammatory activation play a key role during ACS.

Objective

We aimed to evaluate the age-specific prognostic potential of the platelet to lymphocyte ratio (PLR) on long-term cardiovascular mortality after ACS.

Methods

Patients presenting with ACS admitted to a tertiary care centre with a high-volume cardiac catheterization unit between December 1996 and January 2010 were recruited within a clinical registry including assessment of peripheral blood samples. The impact of the PLR on survival was assessed by Cox-regression hazard analysis.

Results

We included a total of 681 patients with a median age of 64 years (IQR:45–84). 200 (29.4%) individuals died during the median follow-up time of 8.5 years. A strong and independent association of the PLR with cardiovascular mortality was found in the total study population (adjusted [adj.] hazard ratio [HR] per one standard deviation [1-SD] of 1.52 [95% CI: 1.18–1.96; p&lt;0.001). After stratification in individuals &lt;65 years (n=339) and ≥65 years (n=342), a prognostic effect of the PLR on cardiovascular mortality was solely observed in elderly patients ≥65 years (adj. HR per 1-SD of 1.32 [95% CI: 1.01–1.74]; p=0.045), but not in their younger counterparts &lt;65 years (adj. HR per 1-SD of 1.08 [95% CI: 0.60–1.93]; p=0.804).

Conclusion

The present investigation highlights a strong and independent age-specific association of the PLR with cardiovascular mortality in patients with ACS. The PLR only allows to identify patients ≥65 years at high risk for fatal events after ACS – even from a long-term perspective.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Medical University of Vienna Effect of PLR stratified by age

The prognostic impact of fibroblast growth factor-23 on cardiovascular death after cardiac surgery

Background

Fibroblast growth factor 23 (FGF-23) participates in phosphate and vitamin D metabolism and proved to be associated with an increased risk for fatal events in individuals presenting with cardiovascular disease. In the era of personalized medicine and individualized prognostication, the identification of novel risk markers seems of major importance in terms of state-of-the-art patient care. Since data on the prognostic potential of FGF-23 in individuals undergoing cardiac valve and/or coronary artery bypass graft (CABG) surgery remain scarce, we aimed to investigate the impact of FGF-23 on cardiovascular (CV) death in an unselected patient population after cardiac surgery.

Methods

Within the present investigation, patients undergoing elective cardiac valve and/or CABG surgery were prospectively enrolled at the Department of Cardiac Surgery of our Medical University. Preoperative blood values were assessed immediately before the surgical intervention. FGF-23 concentrations were measured via FGF Quantikine ELISA Kit (R&D Systems, Minneapolis, USA). Patients were followed prospectively until the primary study endpoint (CV death) was reached. Cox regression models were calculated and adjusted for age, sex, diabetes, heart failure, body mass index, prior myocardial infarction, hypertension and coronary artery disease.

Results

In total, 462 patients were included in the present analysis and followed over a median of 3.9 years. During follow-up 67 (14.5%) patients died. The patients' median age was 70 years (interquartile range [IQR] 60 to 75) and 133 (28.8%) were female. The median FGF level in the entire study population was 1.9 pmol/L (IQR 1.2 to 3.5). After stratification into tertiles (T) of FGF-23 (median FGF-23 T1: 0.95 pmol/L [IQR 0.65 to 1.19], T2: 1.93 pmol/L [IQR 1.64 to 2.28] T3: 4.80 pmol/L [IQR 3.54 to 8.09]), patients in the highest FGF-23 tertile had highest rates of CV death (T1: 4.8%, T2: 6.8%, T3: 19.1%; P-logrank &lt;0.001; Figure A). Moreover, there was a strong association between FGF-23 and CV death (Adj. hazard ratio for 1-unit increase in standardized log-transformed biomarker 1.44, 95% CI: 1.19 to 1.75; P-value &lt;0.001). The risk of CV death increased within higher tertiles of FGF-23 (T3: adj. HR 3.59 [95% CI 1.48–8.71], P-value= 0.005) (T1 was chosen as reference). FGF23 also showed good discriminatory performance (area under the curve [AUC] 0.69, 95% CI 0.61–0.77).

Conclusion

FGF-23 proved to be a strong and independent predictor for CV death in individuals undergoing elective cardiac valve and/or CABG surgery. This biomarker may provide improved risk assessment and fosters individualized patient care in this highly vulnerable patient population in the era of personalized medicine.

Funding Acknowledgement

Type of funding sources: None. Figure 1. Kaplan Meier curves

The prognostic potential of growth differentiation factor-15 on bleeding events and patient outcome after cardiac surgery

Background

GDF-15 (growth/differentiation factor 15) is induced by myocardial stretch, volume overload, inflammation and oxidative stress. Its expression is tightly linked with cardiovascular events as well as the risk for major bleeding and all-cause mortality.

Objective

The objective of the present study was to elucidate the prognostic potential of GDF-15 in patients after cardiac surgery.

Methods

504 patients undergoing elective cardiac valve and/or coronary artery bypass graft surgery were prospectively enrolled. GDF-15 levels were measured prior surgery to evaluate the impact on bleeding events, thromboembolic events and mortality.

Results

Preoperative GDF-15 was associated with the primary endpoint of intra- and postoperative red blood cell transfusion (for bleeding risk factors adjusted [adj] OR [odds ratio] per 1-SD [standard deviation] of 1.62 [95% CI: 1.31–2.00]; p&lt;0.001) and postoperative atrial fibrillation (for atrial fibrillation risk factors adj. OR per 1-SD of 1.49 [95% CI: 1.22–1.81]; p&lt;0.001). Higher concentrations of GDF-15 were observed in patients reaching the secondary endpoint of major or clinically relevant minor bleeding (for bleeding risk factors adj. OR per 1-SD of 1.70 [95% CI: 1.05–2.75]; p=0.030) during the 1stpostoperative year, but not for thromboembolic events. GDF-15 was a predictor for cardiovascular mortality (for comorbidities adj. HR [hazard ratio] per 1-SD of 1.67 [95% CI: 1.23–2.27]; p=0.001) and all-cause mortality (for comorbidities adj. HR per 1-SD of 1.55 [95% CI: 1.19–2.01]; p=0.001). A combined risk model of GDF-15 and EuroSCORE II outperformed the EuroSCORE II alone for long-term survival (c-index: 0.75 [95% CI: 0.70–0.80], p=0.046; net reclassification improvement: 33.6%, p&lt;0.001).

Conclusion

Preoperative GDF-15 concentration is an independent predictor for intra- and postoperative major bleeding, major bleeding during the first year and for long-term cardiovascular or all-cause mortality after cardiac surgery.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Medical University of Vienna Central illustration

Influence of diabetes, heart failure, and NT-proBNP on cardiovascular outcomes in patients with atrial fibrillation – insights from a cohort study of 7,412 patients with extended follow-up

Background

Diabetes and heart failure (HF) promote atrial fibrillation (AF) and are associated with an increased risk of adverse cardiovascular (CV) events in patients with AF. Because of effective anticoagulation options, AF patients are now more likely to develop HF than a stroke or a systemic embolic event. Appropriate risk stratification of patients with AF should therefore not only consider the risk for stroke but also for HF events.

Methods

Patients with AF admitted to a tertiary academic center between 01/2005 and 07/2019 were identified through a search of electronic health records. The primary outcome of interest was CV death or hospitalization for HF (HHF). We used Cox regression models adjusted for age, sex, estimated glomerular filtration rate, diabetes, HF, body mass index, prior myocardial infarction, hypertension, smoking, C-reactive protein, and LDL-C. To select the most informative variables and overcome the limitations of stepwise regression procedures, we performed a least absolute shrinkage and selection operator logistic regression in a model that incorporated diabetes, HF, NT-proBNP, and the covariates for adjustment in combination with 10-fold cross-validation.

Results

In total, 7,412 patients (median age 70 years, 39.7% female) were included in the present analysis and followed over a median of 4.6 years. Both diabetes (Adjusted (Adj.) hazard ratio (HR) 1.87, 95% confidence interval (CI) 1.55 to 2.25) and HF (Adj. HR 2.57, 95% CI 2.22 to 2.98) were significantly associated with CV death/HHF after multivariable adjustment. Compared to patients with diabetes, HF patients had a higher risk of HHF but a similar risk of CV and all-cause death. There was a robust relationship between CV death/HHF and NT-proBNP (Adj. HR for 1-unit increase in standardized log-transformed biomarker 1.86, 95% CI 1.67 to 2.07). NT-proBNP showed good discriminatory performance (AUC 0.78, 95% CI 0.77–0.80), and the addition of NT-proBNP to the covariates used for adjustment resulted in a significant AUC improvement (Δ=0.04, P&lt;0.001). With least absolute shrinkage and selection operator logistic regression, the strongest associations for CV death/HHF were obtained for NT-proBNP (OR 2.69 per 1-SD in log-transformed biomarker), HF (OR 1.73), and diabetes (OR 1.65).

Conclusion

These findings suggest that the influence of diabetes and HF expand beyond the risk of stroke and systemic embolic events to CV death/HHF in an unselected AF patient population. NT-proBNP may provide improved risk assessment in AF patients.

Funding Acknowledgement

Type of funding sources: None. Figure 1. Forest Plot

Structure and Zeatin Binding of the Peach Allergen Pru p 1

Peach (Prunus persica) is among the fruits most frequently reported to cause food allergies. Allergic reactions commonly result from previous sensitization to the birch pollen allergen Bet v 1, followed by immunological cross-reactivity of IgE antibodies to structurally related proteins in peach. In this study, we present the three-dimensional NMR solution structure of the cross-reactive peach allergen Pru p 1 (isoform Pru p 1.0101). This 17.5 kDa protein adopts the canonical Bet v 1 fold, composed of a seven-stranded β-sheet and three α-helices enclosing an internal cavity. In Pru p 1, the inner surface of the cavity contains an array of hydroxyl-bearing amino acids surrounded by a hydrophobic patch, constituting a docking site for amphiphilic molecules. NMR-guided docking of the cytokinin molecule zeatin to the internal cavity of Pru p 1 provides a structure-based rationale for the effect that zeatin binding has on the protein's RNase activity.

Polarizable and non-polarizable force fields: Protein folding, unfolding, and misfolding

Molecular dynamics simulations are an invaluable tool to characterize the dynamic motions of proteins in atomistic detail. However, the accuracy of models derived from simulations inevitably relies on the quality of the underlying force field. Here, we present an evaluation of current non-polarizable and polarizable force fields (AMBER ff14SB, CHARMM 36m, GROMOS 54A7, and Drude 2013) based on the long-standing biophysical challenge of protein folding. We quantify the thermodynamics and kinetics of the β-hairpin formation using Markov state models of the fast-folding mini-protein CLN025. Furthermore, we study the (partial) folding dynamics of two more complex systems, a villin headpiece variant and a WW domain. Surprisingly, the polarizable force field in our set, Drude 2013, consistently leads to destabilization of the native state, regardless of the secondary structure element present. All non-polarizable force fields, on the other hand, stably characterize the native state ensembles in most cases even when starting from a partially unfolded conformation. Focusing on CLN025, we find that the conformational space captured with AMBER ff14SB and CHARMM 36m is comparable, but the ensembles from CHARMM 36m simulations are clearly shifted toward disordered conformations. While the AMBER ff14SB ensemble overstabilizes the native fold, CHARMM 36m and GROMOS 54A7 ensembles both agree remarkably well with experimental state populations. In addition, GROMOS 54A7 also reproduces experimental folding times most accurately. Our results further indicate an over-stabilization of helical structures with AMBER ff14SB. Nevertheless, the presented investigations strongly imply that reliable (un)folding dynamics of small proteins can be captured in feasible computational time with current additive force fields.

Implementation of the Freely Jointed Chain Model to Assess Kinetics and Thermodynamics of Thermosensitive Coil-Globule Transition by Markov States

We revived and implemented a method developed by Kuhn in 1934, originally only published in German, that is, the so-called “freely jointed chain” model. This approach turned out to be surprisingly useful for analyzing state-of-the-art computer simulations of the thermosensitive coil–globule transition of N-Isopropylacrylamide 20-mer. Our atomistic computer simulations are orders of magnitude longer than those of previous studies and lead to a reliable description of thermodynamics and kinetics at many different temperatures. The freely jointed chain model provides a coordinate system, which allows us to construct a Markov state model of the conformational transitions. Furthermore, this guarantees a reliable reconstruction of the kinetics in back-and-forth directions. In addition, we obtain a description of the high diversity and variability of both conformational states. Thus, we gain a detailed understanding of the coil–globule transition. Surprisingly, conformational entropy turns out to play only a minor role in the thermodynamic balance of the process. Moreover, we show that the radius of gyration is an unexpectedly unsuitable coordinate to comprehend the transition kinetics because it does not capture the high conformational diversity within the different states. Consequently, the approach presented here allows for an exhaustive description and resolution of the conformational ensembles of arbitrary linear polymer chains.

X-Entropy: A Parallelized Kernel Density Estimator with Automated Bandwidth Selection to Calculate Entropy

X-Entropy is a Python package used to calculate the entropy of a given distribution, in this case, based on the distribution of dihedral angles. The dihedral entropy facilitates an alignment-independent measure of local protein flexibility. The key feature of our approach is a Gaussian kernel density estimation (KDE) using a plug-in bandwidth selection, which is fully implemented in a C++ backend and parallelized with OpenMP. We further provide a Python frontend, with predefined wrapper functions for classical coordinate-based dihedral entropy calculations, using a 1D approximation. This makes the package very straightforward to include in any Python-based analysis workflow. Furthermore, the frontend allows full access to the C++ backend, so that the KDE can be used on any binnable one-dimensional input data. In this application note, we discuss implementation and usage details and illustrate potential applications. In particular, we benchmark the performance of our module in calculating the entropy of samples drawn from a Gaussian distribution and the analytical solution thereof. Further, we analyze the computational performance of this module compared to well-established python libraries that perform KDE analyses. X-Entropy is available free of charge on GitHub (https://github.com/liedllab/X-Entropy).

Conformational Shifts of Stacked Heteroaromatics: Vacuum vs. Water Studied by Machine Learning

Stacking interactions play a crucial role in drug design, as we can find aromatic cores or scaffolds in almost any available small molecule drug. To predict optimal binding geometries and enhance stacking interactions, usually high-level quantum mechanical calculations are performed. These calculations have two major drawbacks: they are very time consuming, and solvation can only be considered using implicit solvation. Therefore, most calculations are performed in vacuum. However, recent studies have revealed a direct correlation between the desolvation penalty, vacuum stacking interactions and binding affinity, making predictions even more difficult. To overcome the drawbacks of quantum mechanical calculations, in this study we use neural networks to perform fast geometry optimizations and molecular dynamics simulations of heteroaromatics stacked with toluene in vacuum and in explicit solvation. We show that the resulting energies in vacuum are in good agreement with high-level quantum mechanical calculations. Furthermore, we show that using explicit solvation substantially influences the favored orientations of heteroaromatic rings thereby emphasizing the necessity to include solvation properties starting from the earliest phases of drug design.

Mutation of Framework Residue H71 Results in Different Antibody Paratope States in Solution

Characterizing and understanding the antibody binding interface have become a pre-requisite for rational antibody design and engineering. The antigen-binding site is formed by six hypervariable loops, known as the complementarity determining regions (CDRs) and by the relative interdomain orientation (V_H-V_L). Antibody CDR loops with a certain sequence have been thought to be limited to a single static canonical conformation determining their binding properties. However, it has been shown that antibodies exist as ensembles of multiple paratope states, which are defined by a characteristic combination of CDR loop conformations and interdomain orientations. In this study, we thermodynamically and kinetically characterize the prominent role of residue 71^H (Chothia nomenclature), which does not only codetermine the canonical conformation of the CDR-H2 loop but also results in changes in conformational diversity and population shifts of the CDR-H1 and CDR-H3 loop. As all CDR loop movements are correlated, conformational rearrangements of the heavy chain CDR loops also induce conformational changes in the CDR-L1, CDR-L2, and CDR-L3 loop. These overall conformational changes of the CDR loops also influence the interface angle distributions, consequentially leading to different paratope states in solution. Thus, the type of residue of 71^H, either an alanine or an arginine, not only influences the CDR-H2 loop ensembles, but co-determines the paratope states in solution. Characterization of the functional consequences of mutations of residue 71^H on the paratope states and interface orientations has broad implications in the field of antibody engineering.

Inverse relation between structural flexibility and IgE reactivity of Cor a 1 hazelnut allergens

A major proportion of allergic reactions to hazelnuts (Corylus avellana) are caused by immunologic cross-reactivity of IgE antibodies to pathogenesis-related class 10 (PR-10) proteins. Intriguingly, the four known isoforms of the hazelnut PR-10 allergen Cor a 1, denoted as Cor a 1.0401-Cor a 1.0404, share sequence identities exceeding 97% but possess different immunologic properties. In this work we describe the NMR solution structures of these proteins and provide an in-depth study of their biophysical properties. Despite sharing highly similar three-dimensional structures, the four isoforms exhibit remarkable differences regarding structural flexibility, hydrogen bonding and thermal stability. Our experimental data reveal an inverse relation between structural flexibility and IgE-binding in ELISA experiments, with the most flexible isoform having the lowest IgE-binding potential, while the isoform with the most rigid backbone scaffold displays the highest immunologic reactivity. These results point towards a significant entropic contribution to the process of antibody binding.

pH-Induced Local Unfolding of the Phl p 6 Pollen Allergen From cpH-MD

Susceptibility to endosomal degradation is a decisive contribution to a protein's immunogenicity. It is assumed that the processing kinetics of structured proteins are inherently linked to their probability of local unfolding. In this study, we quantify the impact of endosomal acidification on the conformational stability of the major timothy grass pollen allergen Phl p 6. We use state of the art sampling approaches in combination with constant pH MD techniques to profile pH-dependent local unfolding events in atomistic detail. Integrating our findings into the current view on type 1 allergic sensitization, we characterize local protein dynamics in the context of proteolytic degradation at neutral and acidic pH for the wild type protein and point mutants with varying proteolytic stability. We analyze extensive simulation data using Markov state models and retrieve highly reliable thermodynamic and kinetic information at varying pH levels. Thereby we capture the impact of endolysosomal acidification on the structure and dynamics of the Phl p 6 mutants. We find that upon protonation at lower pH values, the conformational flexibilities in key areas of the wild type protein, i.e., T-cell epitopes and early proteolytic cleavage sites, increase significantly. A decrease of the pH even leads to local unfolding in otherwise stable secondary structure elements, which is a prerequisite for proteolytic cleavage. This effect is even more pronounced in the destabilized mutant, while no unfolding was observed for the stabilized mutant. In summary, we report detailed structural models which rationalize the experimentally observed cleavage pattern during endosomal acidification.

Conformational Ensembles of Antibodies Determine Their Hydrophobicity

A major challenge in the development of antibody biotherapeutics is their tendency to aggregate. One root cause for aggregation is exposure of hydrophobic surface regions to the solvent. Many current techniques predict the relative aggregation propensity of antibodies via precalculated scales for the hydrophobicity or aggregation propensity of single amino acids. However, those scales cannot describe the nonadditive effects of a residue’s surrounding on its hydrophobicity. Therefore, they are inherently limited in their ability to describe the impact of subtle differences in molecular structure on the overall hydrophobicity. Here, we introduce a physics-based approach to describe hydrophobicity in terms of the hydration free energy using grid inhomogeneous solvation theory (GIST). We apply this method to assess the effects of starting structures, conformational sampling, and protonation states on the hydrophobicity of antibodies. Our results reveal that high-quality starting structures, i.e., crystal structures, are crucial for the prediction of hydrophobicity and that conformational sampling can compensate errors introduced by the starting structure. On the other hand, sampling of protonation states only leads to good results when combined with high-quality structures, whereas it can even be detrimental otherwise. We conclude by pointing out that a single static homology model may not be adequate for predicting hydrophobicity.

Adherence to cardiac rehabilitation after acute coronary syndrome and its impact on patient outcome

Background

Secondary prevention after acute coronary syndrome (ACS) mirrors a key position in the reduction of morbidity and mortality in this highly vulnerable patient population. Especially cardiac rehabilitation proved to be one of the most beneficial therapeutic approaches for the reduction of re-events and overall modification of cardiovascular risk factors. However, profound epidemiological measures on adherence to a recommended cardiac rehabilitation after ACS remain scare, but seem of major importance in terms of preventing fatal cardiac adverse events. Therefore, we aimed to investigate adherence to cardiac rehabilitation after ACS and its impact on patient outcome from an Austrian nationwide perspective.

Methods

Within this population-based national observation all patients presenting with ACS between 04/2011 and 8/2015 in Austria were enrolled. Patient characteristics and co-morbidities were assessed via the Austrian national health insurance system and elucidated according to ICD10 definitions. Adherence to recommended cardiac rehabilitation was investigated according to health insurance documentation. Patients were followed prospectively until the primary study endpoint (= mortality) was reached. Cox Regression hazard analysis was used to investigate the impact of non-adherence to cardiac rehabilitation on patient outcome and was adjusted for a comprehensive subset of confounders within the multivariate model.

Results

During the observation period a total of 16.518 patients (median age: 64 years [54–74]; male: 68.4% [n=11.306]) met the inclusion criteria. Of alarming importance 86.6% (n=14.305) of all patients presenting with ACS did not perform any cardiac rehabilitation as recommended by current guidelines. During patient follow-up until 01/2018 a total of 1774 (10.7%) individuals died. Adherence to recommended cardiac rehabilitation had a strong an independent inverse association with mortality with an adjusted hazard ratio of 0.73 (95% CI: 0.54–0.98; p=0.036) (see Figure 1).

Conclusion

The present nationwide investigation highlighted an overall low adherence to recommended cardiac rehabilitation after ACS. Since cardiac rehabilitation after ACS was associated with a 27% risk reduction for fatal cardiovascular events during the observation period, awareness in terms of cardiac rehabilitation and associated intensified risk factor modification should be promoted, in order to prevent fatal atherothrombotic events.

Figure 1. Cumulative mortality

Funding Acknowledgement

Type of funding source: None

Prognostic impact of left ventricular thrombus resolution after myocardial infarction on cardiovascular events and mortality

Background

Left ventricular thrombus (LVT) is a rare but dreaded complication during the acute phase of acute coronary syndrome (ACS). Incidence rates differ among the observational studies from 1.6% up to 39.0% indicating that many LVT cases might remain undetected. While the prognosis of patients presenting with LVT after ACS has been controversially discussed, it seems intuitive that individuals in whom the thrombus remains have an increased risk for cardiovascular events and mortality. However, profound data on long-term outcome of this highly vulnerable patient population are not available in current literature. Therefore, we aimed to investigate the impact of LVT resolution on patient's outcome from a long-term perspective.

Methods

We collected data of patients with acute coronary syndrome (n=2011) who underwent treatment between 01/2016 and 09/2019. Patients with a confirmed LVT were included in this analysis. Repeated echocardiographic data, treatment management and clinical outcomes were collected during follow-up. All-cause mortality and major adverse cardiac events (MACE), defined as nonfatal stroke, nonfatal myocardial infarction, nonfatal systemic embolism and cardiovascular death were chosen as primary and secondary endpoint.

Results

Among 2011 patients with ACS, 52 patients (2.6%) developed left ventricular thrombosis (median age: 63±13). 80.5% of LVT patients presented with STEMI. Out of those 52 patients with LVT, 6 died before hospital discharge and 3 did not receive follow-up imaging. In total 13 patients (24%) died. Mean time to thrombus resolution was 23±31 weeks. Mean follow-up time was 98±69.6 weeks. 43 patients received oral anticoagulation including 7 patients (16%) receiving novel oral anticoagulants (NOACs) and 32 patients (84%) Vitamin K antagonists (VKA). All patients developed LVT after anterior wall infarction. From the time of hospital admission all patients were followed prospectively until the primary endpoint was reached. Thrombus resolution was observed in 27 patients (62.8). As expected, thrombus resolution was associated with a significant lower risk of MACE with a crude hazard ratio (HR) of 3.89 (95% CI 1.30–11.65; P=0.015) and mortality with a crude HR of 5.59 (95% CI 1.07–29.07; P=0.041). Notably, the prognostic impact remained stable after comprehensive adjustment for potential confounders with an adjusted HR of 5.38 for MACE and an adjusted HR of 6.10 for overall mortality.

Conclusion

Present data clearly highlighted the prognostic potential of thrombus resolution on both MACE and all-cause mortality in individuals presenting with LVT after ACS. Therefore, thrombus resolution might be considered for risk stratification and an intensified anti-thrombotic approach should be taken into account in this highly vulnerable patient population.

Survival curves

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): Medical University of Vienna

Adherence to high-intensity statin therapy after acute coronary syndrome and its impact on patient outcome

Background

Secondary prevention after acute coronary syndrome (ACS) mirrors a key position in the reduction of morbidity and mortality in this highly vulnerable patient population. Especially lipid lowering therapy – via high-intensity statins (atorvastatin and rosuvastatin) – proved to be one of the most beneficial therapeutic approaches for the reduction of re-events and stent thrombosis. However, profound epidemiological measures on adherence to statin intake after ACS remain scare, but seem of major importance in terms of preventing fatal cardiac adverse events. Therefore, we aimed to investigate adherence to high-intensity statin therapy after ACS and its impact on patient outcome from an Austrian nationwide perspective.

Methods

Within this population-based national observation all patients presenting with ACS between 04/2011 and 8/2015 in Austria were enrolled. Patient characteristics and co-morbidities were assessed via the Austrian national health insurance system and elucidated according to ICD10 definitions. Adherence to high-intensity statins was investigated according to handing in prescriptions for rosuvastatin and atorvastatin at local pharmacies. Patients were followed prospectively until the primary study endpoint (=mortality) was reached. Cox Regression hazard analysis was used to investigate the impact of non-adherence to high-intensity statin therapy on patient outcome and was adjusted for a comprehensive subset of confounders within the multivariate model.

Results

During the observation period a total of 23.240 patients (median age: 65 years [55–75]; male: 67.7% [n=15.728]) met the inclusion criteria. Individuals that died during the index event (n=366; 1.6%), presented with a re-ACS (n=569; 2.4%) or were lost during follow-up (n=158; 0.6%) were not included within the final analysis. Of alarming importance 66.4% (n=15.422) of all patients presenting with ACS did not take high-intensity statins as recommended by current guidelines. The highest rate of drug interruption/end of therapy was observed within the first month after the index event with more than 50% of all cases. During patient follow-up until 01/2018 a total of 3522 (15.2%) individuals died. Non-adherence to high-intensity statins had a strong an independent association with mortality with an adjusted hazard ratio of 1.16 (95% CI: 1.06–1.25; p&lt;0.001) (see Figure 1).

Conclusion

The present nationwide investigation highlighted an overall low adherence to high-intensity statins after ACS, with the highest interruption/end of therapy rate within the first month after the index event. Since the intake of high-intensity statins after ACS was associated with a 14% risk reduction for fatal cardiovascular events during the observation period, awareness in terms of drug-adherence and intensified patient follow-up should be promoted, in order to prevent fatal atherothrombotic events.

Figure 1. Cumulative mortality

Funding Acknowledgement

Type of funding source: None

Adherence to dual anti-platelet therapy after acute coronary syndrome and its impact on patient outcome

Background

Secondary prevention after acute coronary syndrome (ACS) mirrors a key position in the reduction of morbidity and mortality in this highly vulnerable patient population. Especially dual anti-platelet therapy (DAPT) – including aspirin plus a P2Y12 inhibitor – proved to be one of the most beneficial therapeutic approaches for the reduction of re-events and stent thrombosis. However, profound epidemiological measures on adherence to DAPT intake after ACS remain scare, but seem of major importance in terms of preventing fatal cardiac adverse events. Therefore, we aimed to investigate adherence to DAPT after ACS and its impact on patient outcome from an Austrian nationwide perspective.

Methods

Within this population-based national observation all patients presenting with ACS between 04/2011 and 8/2015 in Austria were enrolled. Patient characteristics and co-morbidities were assessed via the Austrian national health insurance system and elucidated according to ICD10 definitions. Adherence to DAPT was investigated according to handing in prescriptions for aspirin and P2Y12 inhibitors at local pharmacies. Patients were followed prospectively until the primary study endpoint (=mortality) was reached. Cox Regression hazard analysis was used to investigate the impact of non-adherence to DAPT on patient outcome and was adjusted for a comprehensive subset of confounders within the multivariate model.

Results

During the observation period a total of 22.331 patients (median age: 65 years [55–75]; male: 69.7% [n=15.176]) met the inclusion criteria. Patients presenting with the indication for oral anticoagulation (n=2165; 9.7%), individuals that died during the index event (n=151; 0.7%), patients that presented with a re-ACS (n=396; 1.7%) or those who were lost during follow-up (n=96; 0.4%) were not included within the final analysis. Of alarming importance 70.7% (n=15.792) of all patients presenting with ACS did not take DAPT as recommended by current guidelines. The highest rate of drug interruption/end of therapy was observed within the first month after the index event with almost 50% of all cases. During patient follow-up until 14 months after the index event 513 individuals died. Non-adherence to DAPT proved a strong an independent association with mortality with an adjusted hazard ratio of 1.25 (95% CI: 1.09–1.41; p&lt;0.001). (see Figure 1)

Conclusion

The present nationwide investigation highlighted an overall low adherence to DAPT after ACS, with the highest interruption/end of therapy rate within the first month after the index event. Since the intake of DAPT after ACS was associated with a 20% risk reduction for fatal cardiovascular events during the observation period, awareness in terms of drug-adherence and intensified patient follow-up should be promoted, in order to prevent fatal atherothrombotic events.

Figure 1. Cumulative Mortality

Funding Acknowledgement

Type of funding source: None

Solvation Thermodynamics in Different Solvents: Water-Chloroform Partition Coefficients from Grid Inhomogeneous Solvation Theory

Reliable information on partition coefficients plays a key role in drug development, as solubility decisively affects bioavailability. In a physicochemical context, the partition coefficient of a solute between two different solvents can be described as a function of solvation free energies. Hence, substantial scientific efforts have been made toward accurate predictions of solvation free energies in various solvents. The grid inhomogeneous solvation theory (GIST) facilitates the calculation of solvation free energies. In this study, we introduce an extended version of the GIST algorithm, which enables the calculation for chloroform in addition to water. Furthermore, GIST allows localization of enthalpic and entropic contributions. We test our approach by calculating partition coefficients between water and chloroform for a set of eight small molecules. We report a Pearson correlation coefficient of 0.96 between experimentally determined and calculated partition coefficients. The capability to reliably predict partition coefficients between water and chloroform and the possibility to localize their contributions allow the optimization of a compound's partition coefficient. Therefore, we presume that this methodology will be of great benefit for the efficient development of pharmaceuticals.

In silico Design of Phl p 6 Variants With Altered Fold-Stability Significantly Impacts Antigen Processing, Immunogenicity and Immune Polarization

Introduction: Understanding, which factors determine the immunogenicity and immune polarizing properties of proteins, is an important prerequisite for designing better vaccines and immunotherapeutics. While extrinsic immune modulatory factors such as pathogen associated molecular patterns are well-understood, far less is known about the contribution of protein inherent features. Protein fold-stability represents such an intrinsic feature contributing to immunogenicity and immune polarization by influencing the amount of peptide-MHC II complexes (pMHCII). Here, we investigated how modulation of the fold-stability of the grass pollen allergen Phl p 6 affects its ability to stimulate immune responses and T cell polarization. Methods: MAESTRO software was used for in silico prediction of stabilizing or destabilizing point mutations. Mutated proteins were expressed in E. coli, and their thermal stability and resistance to endolysosomal proteases was determined. Resulting peptides were analyzed by mass spectrometry. The structure of the most stable mutant protein was assessed by X-ray crystallography. We evaluated the capacity of the mutants to stimulate T cell proliferation in vitro, as well as antibody responses and T cell polarization in vivo in an adjuvant-free BALB/c mouse model. Results: In comparison to wild-type protein, stabilized or destabilized mutants displayed changes in thermal stability ranging from -5 to +14°. While highly stabilized mutants were degraded very slowly, destabilization led to faster proteolytic processing in vitro. This was confirmed in BMDCs, which processed and presented the immunodominant epitope from a destabilized mutant more efficiently compared to a highly stable mutant. In vivo, stabilization resulted in a shift in immune polarization from TH2 to TH1/TH17 as indicated by higher levels of IgG2a and increased secretion of TNF-α, IFN-γ, IL-17, and IL-21. Conclusion: MAESTRO software was very efficient in detecting single point mutations that increase or reduce fold-stability. Thermal stability correlated well with the speed of proteolytic degradation and presentation of peptides on the surface of dendritic cells in vitro. This change in processing kinetics significantly influenced the polarization of T cell responses in vivo. Modulating the fold-stability of proteins thus has the potential to optimize and polarize immune responses, which opens the door to more efficient design of molecular vaccines.

Profiling selectivity of chagasin mutants towards cysteine proteases cruzain or cathepsin L through molecular dynamics simulations

Chagasin, an endogenous cysteine protease inhibitor from Trypanosoma cruzi, can control the activity of the parasitic cruzain and its homologous human cathepsin L. While chagasin inhibits both enzymes with similar potency, mutations have different effects on binding to these enzymes. Mutants T31A and T31A/T32A bind well to cathepsin L, but their affinity for cruzain drops ∼40 to 140-fold. On the other hand, the mutant W93A binds well to cruzain, but it loses potency against cathepsin L. Here, we employed molecular dynamics simulations to understand the selectivity in inhibition of cruzain or cathepsin L by chagasin mutants W93A, T31A, and T31A/T32A. Our results allowed profiling the nonbonded interactions in the interfaces of each mutant with these cysteine proteases. Additionally, we observed differences in the binding conformation of the chagasin loops L2 and L6 of the W93A mutant, favoring interactions with cruzain and reducing interactions with cathepsin L. These differences are associated with a partial dissociation of the W93A-cathepsin L complex, providing a likely cause for the selectivity of the mutant W93A towards cruzain.Communicated by Ramaswamy H. Sarma.

Macrocycle Cell Permeability Measured by Solvation Free Energies in Polar and Apolar Environments

The relation of surface polarity and conformational preferences is decisive for cell permeability and thus bioavailability of macrocyclic drugs. Here, we employ grid inhomogeneous solvation theory (GIST) to calculate solvation free energies for a series of six macrocycles in water and chloroform as a measure of passive membrane permeability. We perform accelerated molecular dynamics simulations to capture a diverse structural ensemble in water and chloroform, allowing for a direct profiling of solvent-dependent conformational preferences. Subsequent GIST calculations facilitate a quantitative measure of solvent preference in the form of a transfer free energy, calculated from the ensemble-averaged solvation free energies in water and chloroform. Hence, the proposed method considers how the conformational diversity of macrocycles in polar and apolar solvents translates into transfer free energies. Following this strategy, we find a striking correlation of 0.92 between experimentally determined cell permeabilities and calculated transfer free energies. For the studied model systems, we find that the transfer free energy exceeds the purely water-based solvation free energies as a reliable estimate of cell permeability and that conformational sampling is imperative for a physically meaningful model. We thus recommend this purely physics-based approach as a computational tool to assess cell permeabilities of macrocyclic drug candidates.

Catalytic Site pKa Values of Aspartic, Cysteine, and Serine Proteases: Constant pH MD Simulations

Enzymatic function and activity of proteases is closely controlled by the pH value. The protonation states of titratable residues in the active site react to changes in the pH value, according to their pK_a, and thereby determine the functionality of the enzyme. Knowledge of the titration behavior of these residues is crucial for the development of drugs targeting the active site residues. However, experimental pK_a data are scarce, since the systems’ size and complexity make determination of these pK_a values inherently difficult. In this study, we use single pH constant pH MD simulations as a fast and robust tool to estimate the active site pK_a values of a set of aspartic, cysteine, and serine proteases. We capture characteristic pK_a shifts of the active site residues, which dictate the experimentally determined activity profiles of the respective protease family. We find clear differences of active site pK_a values within the respective families, which closely match the experimentally determined pH preferences of the respective proteases. These shifts are caused by a distinct network of electrostatic interactions characteristic for each protease family. While we find convincing agreement with experimental data for serine and aspartic proteases, we observe clear deficiencies in the description of the titration behavior of cysteines within the constant pH MD framework and highlight opportunities for improvement. Consequently, with this work, we provide a concise set of active site pK_a values of aspartic and serine proteases, which could serve as reference for future theoretical as well as experimental studies.

Comorbidities cluster with impaired functional capacities and depressive mood and predict adverse outcome in older patients with hematological malignancies

This study evaluates prevalence of comorbidities and their association with impairments in older patients with hematological malignancies at initial diagnosis (n = 209). At least one comorbidity was present in 62.2%, 68.5% and 93.8% as defined by CCI (Charlson Comorbidity Index), Cumulative Illness Rating Scale-Geriatric (CIRS-G) and HCT-Comorbidity Index, respectively. Severe comorbidities (CIRS-G Grade 3/4) were present in 57.9%. The mean number of affected organ systems was 3.6 (CIRS-G categories), with diabetes (18.2%), congestive heart failure and prior solid tumors (each 17.7%) detected most frequently. Comorbidities were significantly correlated with reduced functional and objective physical capacities, impaired performance and depressive mood. Both CCI and CIRS-G were found to be prognostic factors for OS (p < 0.05). CCI scoring of comorbidities, diagnosis MDS/AML and a body mass index <23kg/m² were independent adverse predictors for OS. This first prospective analysis reveals a prognostic significance of comorbidities. Clustering of comorbidities with impairments suggests common mechanisms.

Dynamics Rationalize Proteolytic Susceptibility of the Major Birch Pollen Allergen Bet v 1

Proteolytic susceptibility during endolysosomal degradation is decisive for allergic sensitization. In the major birch pollen allergen Bet v 1 most protease cleavage sites are located within its secondary structure elements, which are inherently inaccessible to proteases. The allergen thus must unfold locally, exposing the cleavage sites to become susceptible to proteolysis. Hence, allergen cleavage rates are presumed to be linked to their fold stability, i.e., unfolding probability. Yet, these locally unfolded structures have neither been captured in experiment nor simulation due to limitations in resolution and sampling time, respectively. Here, we perform classic and enhanced molecular dynamics (MD) simulations to quantify fold dynamics on extended timescales of Bet v 1a and two variants with higher and lower cleavage rates. Already at the nanosecond-timescale we observe a significantly higher flexibility for the destabilized variant compared to Bet v 1a and the proteolytically stabilized mutant. Estimating the thermodynamics and kinetics of local unfolding around an initial cleavage site, we find that the Bet v 1 variant with the highest cleavage rate also shows the highest probability for local unfolding. For the stabilized mutant on the other hand we only find minimal unfolding probability. These results strengthen the link between the conformational dynamics of allergen proteins and their stability during endolysosomal degradation. The presented approach further allows atomistic insights in the conformational ensemble of allergen proteins and provides probability estimates below experimental detection limits.

Conformational selection of allergen-antibody complexes-surface plasticity of paratopes and epitopes

Antibodies have the ability to bind various types of antigens and to recognize different antibody-binding sites (epitopes) of the same antigen with different binding affinities. Due to the conserved structural framework of antibodies, their specificity to antigens is mainly determined by their antigen-binding site (paratope). Therefore, characterization of epitopes in combination with describing the involved conformational changes of the paratope upon binding is crucial in understanding and predicting antibody-antigen binding. Using molecular dynamics simulations complemented with strong experimental structural information, we investigated the underlying binding mechanism and the resulting local and global surface plasticity in the binding interfaces of distinct antibody-antigen complexes. In all studied allergen-antibody complexes, we clearly observe that experimentally suggested epitopes reveal less plasticity, while non-epitope regions show high surface plasticity. Surprisingly, the paratope shows higher conformational diversity reflected in substantially higher surface plasticity, compared to the epitope. This work allows a visualization and characterization of antibody-antigen interfaces and might have strong implications for antibody-antigen docking and in the area of epitope prediction.

pH-Dependent Protonation of the Phl p 6 Pollen Allergen Studied by NMR and cpH-aMD

We use state-of-the-art NMR experiments to measure apparent pK_a values in the native protein environment and employ a cutting-edge combination of enhanced sampling and constant pH molecular dynamics (MD) simulations to rationalize strong pK_a shifts. The major timothy grass pollen allergen Phl p 6 serves as an ideal model system for both methods due to its high number of titratable residues despite its comparably small size. We present a proton transition analysis as intuitive tool to depict the captured protonation state ensemble in atomistic detail. Combining microscopic structural details from MD simulations and macroscopic ensemble averages from NMR shifts leads to a comprehensive view on pH dependencies of protonation states and tautomers. Overall, we find striking agreement between simulation-based pK_a predictions and experiment. However, our analyses suggest subtle differences in the underlying molecular origin of the observed pK_a shifts. From accelerated constant pH MD simulations, we identify immediate proximity of opposite charges, followed by vicinity of equal charges as major driving forces for pK_a shifts. NMR experiments on the other hand, suggest only a weak relation of pK_a shifts and close contacts to charged residues, while the strongest influence derives from the dipolar character of α helices. The presented study hence pinpoints opportunities for improvements concerning the theoretical description of protonation state and tautomer probabilities. However, the coherence in the resulting apparent pK_a values from simulations and experiment affirms cpH-aMD as a reliable tool to study allergen dynamics at varying pH levels.

Structural characterization of poly-Si Films crystallized by Ni Metal Induced Lateral Crystallization

The growth of the poly-Si films was studied by Transmission Electron Microscopy (TEM) after Ni Metal Induced Lateral Crystallization (Ni-MILC) of amorphous Si films at 413 °C. Significant differences in the morphology and the mode of growth of the films were observed, in comparison to films grown at temperatures above 500 °C. It was shown that at 413 °C the Solid Phase Crystallization (SPC), which acts in parallel with the Ni-MILC process at temperatures above 500 °C is suppressed. The suppression of SPC results in substantial change in the mode of growth. The poly-Si film grown at 413 °C consists of whiskers, which can be classified into two categories. Those growing fast along the <111> direction, which were already observed in conventional Ni-MILC above 500 °C and whiskers grown along random crystallographic orientations having significantly slower growth rates. Because of the large difference in growth rates of the whiskers, significant orientation filtering due to growth-velocity competition is observed. The uniform poly-Si films consist of a mixture of fast <111> type whiskers and slow ones, grown in other orientations, resulting in a tweed-like structure.

Fatigue at baseline is associated with geriatric impairments and represents an adverse prognostic factor in older patients with a hematological malignancy

Prospective data on fatigue in elderly persons with a hematological malignancy are rare. We aimed to determine the prevalence of fatigue and its association with clinical outcome and geriatric impairments in older individuals newly diagnosed with blood cancer. The EORTC QLQ-C30 and a multidimensional geriatric assessment (MGA) were performed in parallel in 149 consecutive patients aged > 67 years (median 77.8 years) at Innsbruck Medical University between January 2009 and April 2016. Fatigue as defined by EORTC QLQ-C30 was the most prevalent symptom (84%) and was significantly associated with self-reported role and physical functioning, global health status and insomnia, dyspnea, and loss of appetite (p < 0.001). Remarkably, pronounced fatigue was associated with impaired performance status and objective functional capacities in MGA, with altered depression scoring, G8 screening, and elevation of serum inflammation markers (p < 0.001). Patients with minor fatigue had a median overall survival (OS) of 26.4 months, whereas those with marked fatigue displayed an OS of 7.0 months (p < 0.001). The association between fatigue and shortened OS was supported in multivariate analyses (HR 1.74, CI 1.09–2.76; p = 0.021). Fatigue is seen to have a high prevalence and to be an adverse prognostic factor in elderly patients with a hematological malignancy. The strong impact of fatigue on clinical performance and OS emphasizes the relevance of patient-reported outcomes in individualized treatment algorithms. Patients will benefit from identification of fatigue, allowing timely interventions. The correlation between fatigue, impaired performance, nutritional status, and inflammation might suggest an underlying common pathway.

Cost-utility analysis of a potential lung cancer screening program for a high-risk population in Germany: A modelling approach

BACKGROUND

Lung cancer is the leading cause of cancer death in Germany. Although several randomized trials in Europe have evaluated the effectiveness of lung cancer screening programs, evidence on the cost-effectiveness of lung cancer screening is scarce.

OBJECTIVE

To evaluate the cost-effectiveness of a population-based lung cancer screening program from the perspective of a German payer.

METHODS

We conducted a cost-effectiveness analysis from the public payer perspective for a high-risk population defined as heavy former and current smokers (≥20 cigarettes per day) between 55 and 75 years of age. The underlying model consisted of two Markov models. We differentiated between a population-based annual screening program and standard clinical care. Depending on stage at diagnosis, simulated patients were assigned to one of five treatment paths according to the German clinical guideline for the diagnosis and treatment of lung cancer. Costs, life years saved, and quality adjusted life years (QALYs) were used as outcomes. Values for input parameters were taken from the literature. The model was run for 60 cycles with a cycle length of three months. Deterministic and probabilistic sensitivity analyses were conducted.

RESULTS

In the base case, annual lung cancer screening led to an increase in incremental costs (€ 1,153 per person) compared to standard clinical care. However, the screening approach was associated with an incremental gain in life years (0.06 per person) and QALYs (0.04 per person). Thus, the incremental cost-effectiveness ratio (ICER) was € 19,302 per life year saved and € 30,291 per QALY. A probabilistic sensitivity analysis with 10,000 draws resulted in average ICERs of € 22,118 per life year and € 34,841 per QALY.

CONCLUSION

We provide evidence that lung cancer screening for a high-risk population may be more effective, but also more costly, than standard clinical care from the perspective of a German payer.

Protective effect of sugars on storage stability of microwave freeze-dried and freeze-dried Lactobacillus paracasei F19

AIMS

Microwave freeze drying (MWFD) in comparison with conventional freeze drying allows for intensification of the preservation process of lactic acid bacteria without imposing additional processing stress. Viability as a function of storage time of microwave freeze-dried Lactobacillus paracasei ssp. paracasei F19 was investigated in comparison to conventionally lyophilized bacteria of the same strain. Furthermore, the impact of the protectants, sorbitol, trehalose and maltodextrin, on shelf life was analysed.

METHODS AND RESULTS

The highest inactivation rates of 0·035 and 0·045 day^-1 , respectively, were found for cultures without protectants. Thus, all additives were found to exhibit a protective effect during storage with inactivation rates between 0·015 and 0·040 day^-1 . Although trehalose and maltodextrin samples were in the glassy state during storage, in contrast to samples containing sorbitol as protectant, the best protective effect could be found for sorbitol with the lowest inactivation rate of 0·015 day^-1 .

CONCLUSIONS

Due to its low molecular weight, it might protect cells owing to better adsorption to the cytoplasma membrane. Sorbitol additionally shows antioxidative properties. Storage behaviour of microwave freeze-dried cultures follows the typical behaviour of a product dried by conventional lyophilization. No significant influence of the drying technique on storage behaviour was detected.

SIGNIFICANCE AND IMPACT OF THE STUDY

General findings concerning storage behaviour in freeze drying are likely to be applicable in MWFD with only slight adjustments.

Mechanisms Responsible for ω-Pore Currents in Cav Calcium Channel Voltage-Sensing Domains

Mutations of positively charged amino acids in the S4 transmembrane segment of a voltage-gated ion channel form ion-conducting pathways through the voltage-sensing domain, named ω-current. Here, we used structure modeling and MD simulations to predict pathogenic ω-currents in Ca_V1.1 and Ca_V1.3 Ca²⁺ channels bearing several S4 charge mutations. Our modeling predicts that mutations of Ca_V1.1-R1 (R528H/G, R897S) or Ca_V1.1-R2 (R900S, R1239H) linked to hypokalemic periodic paralysis type 1 and of Ca_V1.3-R3 (R990H) identified in aldosterone-producing adenomas conducts ω-currents in resting state, but not during voltage-sensing domain activation. The mechanism responsible for the ω-current and its amplitude depend on the number of charges in S4, the position of the mutated S4 charge and countercharges, and the nature of the replacing amino acid. Functional characterization validates the modeling prediction showing that Ca_V1.3-R990H channels conduct ω-currents at hyperpolarizing potentials, but not upon membrane depolarization compared with wild-type channels.

Role of sulfate, chloride, and nitrate anions on the degradation of fluoroquinolone antibiotics by photoelectro-Fenton

Taking ciprofloxacin (CIP) as a fluoroquinolone antibiotic model, this work explores the role of common anions (sulfate, nitrate, and chloride) during the application of photoelectro-Fenton (PEF) at natural pH to degrade this type of compound in water. The system was composed of an IrO₂ anode, Ti, or gas diffusion electrode (GDE) as cathode, Fe²⁺, and UV (254 nm). To determine the implications of these anions, the degradation pathway and efficiency of the PEF sub-processes (UV photolysis, anodic oxidation, and electro-Fenton at natural pH) were studied in the individual presence of the anions. The results highlight that degradation routes and kinetics are strongly dependent on electrolytes. When chloride and nitrate ions were present, indirect electro-chemical oxidation was identified by electro-generated HOCl and nitrogenated oxidative species, respectively. Additionally, direct photolysis and direct oxidation at the anode surface were identified as degradation routes. As a consequence of the different pathways, six primary CIP by-products were identified. Therefore, a scheme was proposed representing the pathways involved in the degradation of CIP when submitted to PEF in water with chloride, nitrate, and sulfate ions, showing the complexity of this process. Promoted by individual and synergistic actions of this process, the PEF system leads to a complete elimination of CIP with total removal of antibiotic activity against Staphylococcus aureus and Escherichia coli, and significant mineralization. Finally, the role of the anions was tested in seawater containing CIP, in which the positive contributions of the anions were partially suppressed by its OH radical scavenger action. The findings are of interest for the understanding of the degradation of antibiotics via the PEF process in different matrices containing sulfate, nitrate, and chloride ions.

Clinical and Molecular Phenotypes of Low-Penetrance Variants of NLRP3: Diagnostic and Therapeutic Challenges

OBJECTIVE

Cryopyrin-associated periodic syndromes (CAPS) result from gain-of-function mutations in the NLRP3 gene, which causes excessive release of interleukin-1β (IL-1β) and systemic inflammation. While pathogenetic NLRP3 variant phenotypes are well-characterized, low-penetrance NLRP3 variants represent a significant clinical challenge. The aims of this study were to determine the clinical phenotype, the in vitro biologic phenotype, and the effect of anti-IL-1 treatment in patients with low-penetrance NLRP3 variants.

METHODS

A multicenter study of consecutive symptomatic patients with low-penetrance NLRP3 variants recruited from 7 centers between May 2012 and May 2013 was performed. The observed findings were transferred into a study database, from which they were extracted for analysis. Controls were patients with a known pathogenetic NLRP3 variant. Clinical presentation and CAPS markers of inflammation were captured. Functional assays of inflammasome activation, including caspase 1 activity, NF-κB release, cell death, and IL-1β release, were performed. Treatment effects of IL-1 were determined. Comparisons between low-penetrance and pathogenetic NLRP3 variants were performed.

RESULTS

The study included 45 patients, 21 of which were female (47%); 26 of the patients (58%) were children. NLRP3 low-penetrance variants identified in the patients were Q703K (n = 19), R488K (n = 6), and V198M (n = 20). In the controls, 28 had pathogenetic NLRP3 variants. Patients with low-penetrance NLRP3 variants had significantly more fever (76%) and gastrointestinal symptoms (73%); eye disease, hearing loss, and renal involvement were less common. Functional inflammasome testing identified an intermediate phenotype in low-penetrance NLRP3 variants as compared to wild-type and pathogenetic NLRP3 variants. All treated patients responded to IL-1 inhibition, with complete response documented in 50% of patients.

CONCLUSION

Patients with low-penetrance NLRP3 variants display a distinct clinical phenotype and an intermediate biologic phenotype, including IL-1β and non-IL-1β-mediated inflammatory pathway activation.

[Geriatric assessment of patients with hematological neoplasms]

Hematological malignancies are typical diseases of the elderly. The aging of the population in the Western World results in a significant increase in the number of elderly patients with hematological malignant diseases. This has important consequences for medicine. One consequence of this development is that the need for tools for the evaluation of both functional and global status of the elderly increases. The use of these tools enables the hematologist to better stratify the patients, to individualize therapy better, to possibly modify therapy in order to improve implementation of supportive measures and interventions, to minimize toxicity and side effects and ultimately to tailor the treatment to the individual patient. Several tools are available for geriatric assessment (GA) and there is strong evidence that an effective GA can detect previously unknown problems. The targeted intervention improves the prognosis and compliance of therapy in elderly patients with hematological malignant diseases.

Cost-Utility Analysis of Telemonitoring Interventions for Patients with Chronic Obstructive Pulmonary Disease (COPD) in Germany

BACKGROUND

Chronic obstructive pulmonary disease (COPD) poses major challenges for health care systems. Previous studies suggest that telemonitoring could be effective in preventing hospitalisations and hence reduce costs.

OBJECTIVE

The aim was to evaluate whether telemonitoring interventions for COPD are cost-effective from the perspective of German statutory sickness funds.

METHODS

A cost-utility analysis was conducted using a combination of a Markov model and a decision tree. Telemonitoring as add-on to standard treatment was compared with standard treatment alone. The model consisted of four transition stages to account for COPD severity, and a terminal stage for death. Within each cycle, the frequency of exacerbations as well as outcomes for 2015 costs and quality adjusted life years (QALYs) for each stage were calculated. Values for input parameters were taken from the literature. Deterministic and probabilistic sensitivity analyses were conducted.

RESULTS

In the base case, telemonitoring led to an increase in incremental costs (€866 per patient) but also in incremental QALYs (0.05 per patient). The incremental cost-effectiveness ratio (ICER) was thus €17,410 per QALY gained. A deterministic sensitivity analysis showed that hospitalisation rate and costs for telemonitoring equipment greatly affected results. The probabilistic ICER averaged €34,432 per QALY (95 % confidence interval 12,161-56,703).

CONCLUSION

We provide evidence that telemonitoring may be cost-effective in Germany from a payer's point of view. This holds even after deterministic and probabilistic sensitivity analyses.

Focused electron beam induced deposition as a tool to create electron vortices

Focused electron beam induced deposition (FEBID) is a microscopic technique that allows geometrically controlled material deposition with very high spatial resolution. This technique was used to create a spiral aperture capable of generating electron vortex beams in a transmission electron microscope (TEM). The vortex was then fully characterized using different TEM techniques, estimating the average orbital angular momentum to be ∼0.8ℏ per electron with almost 60% of the beam ending up in the ℓ=1 state.