Altered cardiac reserve is a determinant of exercise intolerance in sickle cell anaemia patients.

BACKGROUND: The underlying mechanisms of exercise intolerance in sickle cell anaemia (SCA) patients are complex and not yet completely understood. While latent heart failure at rest could be unmasked upon exercise, most previous studies assessed cardiac function at rest. We aimed to investigate exercise cardiovascular reserve as a potential contributor to exercise intolerance in adult SCA patients. METHODS: In this observational prospective study, we compared prospectively 60 SCA patients (median age 31 years, 60% women) to 20 matched controls. All subjects underwent symptom-limited combined exercise echocardiography and oxygen uptake (VO2 ) measurements. Differences between arterial and venous oxygen content (C(a-v)O2 ) were calculated. Cardiac reserve was defined as the absolute change in cardiac index (Ci) from baseline to peak exercise. RESULTS: Compared to controls, SCA patients demonstrated severe exercise intolerance (median peakVO2 , 34.3 vs. 19.7 ml/min/kg, respectively, p < .0001). SCA patients displayed heterogeneously increased Ci from rest to peak exercise (median +5.8, range 2.6 to 10.6 L/min/m²) which correlated with peakVO2 (r = 0.71, p < .0001). In contrast, the C(a-v)O2 exercise reserve was homogenously reduced and did not correlate with peakVO2 (r = 0.18, p = .16). While haemoglobin level and C(a-v)O2 were similar in SCA subgroups, SCA patients in the lower VO2 tertile had chronotropic incompetence and left ventricular diastolic dysfunction (left atrial peak longitudinal strain was reduced, and both E/e' ratio and left atrial volume index were increased) and were characterized by a reduced cardiac reserve, +5.0[4.2-5.5] compared to +6.7[5.5-7.8] L/min/m² for the rest of the patient cohort, p < .0001. CONCLUSIONS: Altered cardiac reserve due to chronotropic incompetence and left ventricular diastolic dysfunction seems to be an important determinant of exercise intolerance in adult SCA patients.

Reduced Rivaroxaban Dose Versus Dual Antiplatelet Therapy After Left Atrial Appendage Closure: ADRIFT a Randomized Pilot Study.

BACKGROUND: Percutaneous left atrial appendage closure (LAAC) exposes to the risk of device thrombosis in patients with atrial fibrillation who frequently have a contraindication to full anticoagulation. Thereby, dual antiplatelet therapy (DAPT) is usually preferred. No randomized study has evaluated nonvitamin K antagonist oral anticoagulant after LAAC, and we decided to evaluate the efficacy and safety of reduced doses of rivaroxaban after LAAC. METHODS: ADRIFT (Assessment of Dual Antiplatelet Therapy Versus Rivaroxaban in Atrial Fibrillation Patients Treated With Left Atrial Appendage Closure) is a multicenter, phase IIb study, which randomized 105 patients after successful LAAC to either rivaroxaban 10 mg (R10, n=37), rivaroxaban 15 mg (R15, n=35), or DAPT with aspirin 75 mg and clopidogrel 75 mg (n=33). The primary end point was thrombin generation (prothrombin fragments 1+2) measured 2 to 4 hours after drug intake, 10 days after treatment initiation. Thrombin-antithrombin complex, D-dimers, rivaroxaban concentrations were also measured at 10 days and 3 months. Clinical end points were evaluated at 3-month follow-up. RESULTS: The primary end point was reduced with R10 (179 pmol/L [interquartile range (IQR), 129-273], P<0.0001) and R15 (163 pmol/L [IQR, 112-231], P<0.0001) as compared with DAPT (322 pmol/L [IQR, 218-528]). We observed no significant reduction of the primary end point between R10 and R15 while rivaroxaban concentrations increased significantly from 184 ng/mL (IQR, 127-290) with R10 to 274 ng/mL (IQR, 192-377) with R15, P<0.0001. Thrombin-antithrombin complex and D-dimers were numerically lower with both rivaroxaban doses than with DAPT. These findings were all confirmed at 3 months. The clinical end points were not different between groups. A device thrombosis was noted in 2 patients assigned to DAPT. CONCLUSIONS: Thrombin generation measured after LAAC was lower in patients treated by reduced rivaroxaban doses than DAPT, supporting an alternative to the antithrombotic regimens currently used after LAAC and deserves further evaluation in larger studies. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT03273322.

Delivering the power of nanomedicine to patients today.

The situation of the COVID-19 pandemic reminds us that we permanently need high-value flexible solutions to urgent clinical needs including simplified diagnostic technologies suitable for use in the field and for delivering targeted therapeutics. From our perspective nanotechnology is revealed as a vital resource for this, as a generic platform of technical solutions to tackle complex medical challenges. It is towards this perspective and focusing on nanomedicine that we take issue with Prof Park's recent editorial published in the Journal of Controlled Release. Prof. Park argued that in the last 15 years nanomedicine failed to deliver the promised innovative clinical solutions to the patients (Park, K. The beginning of the end of the nanomedicine hype. Journal of Controlled Release, 2019; 305, 221-222 [1]. We, the ETPN (European Technology Platform on Nanomedicine) [2], respectfully disagree. In fact, the more than 50 formulations currently in the market, and the recent approval of 3 key nanomedicine products (e. g. Onpattro, Hensify and Vyxeos), have demonstrated that the nanomedicine field is concretely able to design products that overcome critical barriers in conventional medicine in a unique manner, but also to deliver within the cells new drug-free therapeutic effects by using pure physical modes of action, and therefore make a difference in patients lives. Furthermore, the >400 nanomedicine formulations currently in clinical trials are expecting to bring novel clinical solutions (e.g. platforms for nucleic acid delivery), alone or in combination with other key enabling technologies to the market, including biotechnologies, microfluidics, advanced materials, biomaterials, smart systems, photonics, robotics, textiles, Big Data and ICT (information & communication technologies) more generally. However, we agree with Prof. Park that " it is time to examine the sources of difficulty in clinical translation of nanomedicine and move forward ". But for reaching this goal, the investments to support clinical translation of promising nanomedicine formulations should increase, not decrease. As recently encouraged by EMA in its roadmap to 2025, we should create more unity through a common knowledge hub linking academia, industry, healthcare providers and hopefully policy makers to reduce the current fragmentation of the standardization and regulatory body landscape. We should also promote a strategy of cross-technology innovation, support nanomedicine development as a high value and low-cost solution to answer unmet medical needs and help the most promising innovative projects of the field to get better and faster to the clinic. This global vision is the one that the ETPN chose to encourage for the last fifteen years. All actions should be taken with a clear clinical view in mind, " without any fanfare", to focus "on what matters in real life", which is the patient and his/her quality of life. This ETPN overview of achievements in nanomedicine serves to reinforce our drive towards further expanding and growing the maturity of nanomedicine for global healthcare, accelerating the pace of transformation of its great potential into tangible medical breakthroughs.

No effect of triheptanoin on exercise performance in McArdle disease.

OBJECTIVE: To study if treatment with triheptanoin, a 7-carbon triglyceride, improves exercise tolerance in patients with McArdle disease. McArdle patients have a complete block in glycogenolysis and glycogen-dependent expansion of tricarboxylic acid cycle (TCA), which may restrict fat oxidation. We hypothesized that triheptanoin metabolism generates substrates for the TCA, which potentially boosts fat oxidation and improves exercise tolerance in McArdle disease. METHODS: Double-blind, placebo-controlled, crossover study in patients with McArdle disease completing two treatment periods of 14 days each with a triheptanoin or placebo diet (1 g/kg/day). Primary outcome was change in mean heart rate during 20 min submaximal exercise on a cycle ergometer. Secondary outcomes were change in peak workload and oxygen uptake along with changes in blood metabolites and respiratory quotients. RESULTS: Nineteen of 22 patients completed the trial. Malate levels rose on triheptanoin treatment versus placebo (8.0 ± SD2.3 vs. 5.5 ± SD1.8 µmol/L, P < 0.001), but dropped from rest to exercise (P < 0.001). There was no difference in exercise heart rates between triheptanoin (120 ± SD16 bpm) and placebo (121 ± SD16 bpm) treatments. Compared with placebo, triheptanoin did not change the submaximal respiratory quotient (0.82 ± SD0.05 vs. 0.84 ± SD0.03), peak workload (105 ± SD38 vs. 102 ± SD31 Watts), or peak oxygen uptake (1938 ± SD499 vs. 1977 ± SD380 mL/min). INTERPRETATION: Despite increased resting plasma malate with triheptanoin, the increase was insufficient to generate a normal TCA turnover during exercise and the treatment has no effect on exercise capacity or oxidative metabolism in patients with McArdle disease.

Speckle-Tracking Echocardiographic Strain Analysis Reliably Estimates Degree of Acute LV Unloading During Mechanical LV Support by Impella.

Non-invasive means of evaluating appropriate cardiac unloading remain to be established. We hypothesized that myocardial deformation assessed by echocardiographic speckle-tracking strain analysis can reliably estimate the degree of left ventricular (LV) unloading under mechanical circulatory support. A total of 24 Yorkshire pigs underwent Impella-mediated acute LV unloading 1-2 weeks after myocardial infarction (MI). Echocardiographic and invasive pressure-volume measurements were used to evaluate the degree of LV unloading. Pressure-volume analysis before and after LV unloading exhibited a significant decrease in stroke work (3399 ± 1440 to 1244 ± 659 mmHg ml, p < 0.001), suggesting reduced external cardiac work. Both longitudinal strain (- 14.6 ± 4.1% to - 10.6 ± 2.3%, p < 0.001) and circumferential strain (- 18.7 ± 6.1% to - 9.3 ± 3.5%, p < 0.001) decreased after LV unloading, and there were linear relationships between stroke work and echocardiographic longitudinal (r = - 0.61, p < 0.001) as well as circumferential strains (r = - 0.75, p < 0.001). Echocardiographic LV strain analysis offers a non-invasive assessment of LV unloading in subacute MI.

Copeptin as a prognostic biomarker in acute myocardial infarction.

BACKGROUND: Copeptin - the C-terminal section of vasopressin precursor - is a novel biomarker, that has been shown to be a useful prognostic factor in heart failure, ischemic stroke and in acute myocardial infarction (MI) but with restricted population and follow-up in ST-segment elevation MI (STEMI) setting. We evaluated in this study the hypothesis that copeptin measured on admission is an independent predictor of one-year all-cause mortality after a STEMI. METHODS: Copeptin was measured immediately on arrival in the catheterization laboratory in a cohort of unselected STEMI patients and was compared to the peak of cardiac troponin I as a prognosis marker. One-year follow-up was performed. RESULTS: We included 401 STEMI patients (77% of men, mean age 64 ±â€¯14 years) treated by primary percutaneous coronary intervention. Copeptin on admission was significantly higher in patients who died during the one-year follow-up than in survivors (154.8 pmol/L; IQR [63.9-304.8] vs 30.3 pmol/L; IQR [10.8-93.5]); p < 0.0001). There was an increase in mortality at one year from the lowest to the highest quartile of copeptin. After Cox regression analysis, copeptin was an independent predictor of death at one year (adjHR 3.1, 95% CI [1.5-6.2], p = 0.001). When compared to the peak value of cardiac troponin I, copeptin measured on admission had a better prognostic value to predict one-year mortality (AUC of 0.74 vs 0.60, p = 0.022). CONCLUSION: Copeptin measured on admission is a reliable and independent prognostic biomarker of one-year mortality in acute myocardial infarction patients.

Cardiac manifestations in sickle cell disease varies with patient genotype.

Cardiac involvement is well characterized in sickle cell anaemia (SCA) but cardiac features associated with Haemoglobin SC (HbSC) disease are mostly unknown. We compared 60 patients with HbSC disease (median age 31 years, 25 men) to 60 SCA patients and 60 controls matched for age and gender. Left ventricular ejection fraction (LVEF), left ventricle (LV) mass index (LVMi), cardiac index and peak tricuspid regurgitation velocity (TRV) were measured using echocardiography. LV filling pressures were assessed using the ratio of early diastolic transmitral velocity to tissue velocity (E/e' ratio). The LVMi was higher in both genotypes compared to controls. However, whereas LV hypertrophy was observed only in 3(5%) HbSC patients, this condition was diagnosed in 27(45%) SCA patients (P < 0·0001). While cardiac index and TRV were similar in HbSC compared to controls, SCA patients exhibited elevated cardiac output and TRV. LVEF was similar in the 3 groups. However, both genotypes had a higher E/e' ratio compared to controls. Cardiac involvement in SCA was related to anaemia and haemolysis, while LV diastolic dysfunction and TRV in HbSC disease patients were related to arterial hypertension and overweight comorbidities. In summary, cardiac involvement and its determinants are different in HbSC disease and SCA. Patient's genotype should be considered with regard to the echocardiographic indications and findings.

Impact of negative inotropic drugs on accuracy of diastolic stress echocardiography for evaluation of left ventricular filling pressure.

The ratio of early diastolic trans-mitral flow velocity to tissue-Doppler mitral annular early diastolic velocity (E/e'), and left ventricular end-diastolic pressure(LVEDP) have been shown to be correlated at rest, provided that patients are not on positive inotropic drugs. Data concerning the latter correlation during exercise stress are conflicting. Therefore, we investigated if use of negative inotropic drugs (NID), impacts the accuracy of E/e' as a surrogate for LVEDP during low-level exercise. An exercise(50 watts) during cardiac invasive hemodynamic monitoring and an exercise echocardiography were performed prospectively within 24 hours in 54 patients (81%male, 62 ± 9years) with preserved LV Ejection-Fraction. Before exercise, the patients had scattered LVEDP (13.8 ± 5.8 mmHg) and septal E/e' (8.7 ± 2.7). Half of them were on NID, mainly betablockers(n = 26). The correlation between septal-E/e' and LVEDP was low for examinations performed at rest (r = 0.35,p = 0.01) with no significant impact of NID. For measurements performed at 50 Watts, NID had a significant impact on the association between septal-E/e'50 watts and LVEDP50 watts (ß = -0.28,p = 0.03). Correlation between septal-E/e'50 watts and LVEDP50 watts persisted in patients on NID (r = 0.61,p = 0.001) while it disappeared in the group of patients with no NID (r = 0.15,p = 0.47). NID use is an important confounding factor to take into consideration when assessing exercise LVFP using stress E/e' in patients with preserved LVEF.

Low level exercise echocardiography helps diagnose early stage heart failure with preserved ejection fraction: a study of echocardiography versus catheterization.

BACKGROUND: Increased left ventricular end-diastolic pressure (LVEDP) with exercise is an early sign of heart failure with preserved left ventricular ejection fraction (LVEF). The abnormal exercise increase in LVEDP is nonlinear, with most change occurring at low-level exercise. Data on non-invasive approach of this condition are scarce. Our objective was assessing E/e' to estimate low level exercise LVEDP using a direct invasive measurement as the reference method. METHODS AND RESULTS: Sixty patients with LVEF >50 % prospectively underwent both exercise cardiac catheterization and echocardiography. E/e' was measured at rest and during low-level exercise. Abnormal LVEDP was defined as >16 mmHg. Patients with a history of coronary artery disease and/or abnormal LV morphology were classified as having apparent cardiac disease (CD). Thirty-four (57 %) patients had elevated LVEDP only during exercise. Most of the change in LVEDP occurred since the first exercise level (25 W). There was a correlation between LVEDP and septal E/e' at rest and during exercise. Lateral E/e' and E/average e' ratio had worse correlations with LVEDP. In the whole population, exercise septal E/e' at 25 W had the best accuracy for abnormal exercise LVEDP, area under curve (AUC) = 0.79. However, while low-level exercise septal E/e' had a high accuracy in CD patients (n = 26, AUC = 0.96), E/e' was not linked to LVEDP in patients without CD (n = 34). CONCLUSION: Low-level exercise septal E/e' is valuable for predicting abnormal exercise LVEDP in patients with preserved LVEF and apparent CD. However, this new diagnosis approach appears not reliable in patients with normal LV morphology and without coronary artery disease. CLINICAL TRIAL REGISTRATION: https://clinicaltrials.gov . Unique identifier: NCT01714752.

Synthesis and evaluation of analogues of N-phthaloyl-l-tryptophan (RG108) as inhibitors of DNA methyltransferase 1.

DNA methyltransferases (DNMT) are promising drug targets in cancer provided that new, more specific, and chemically stable inhibitors are discovered. Among the non-nucleoside DNMT inhibitors, N-phthaloyl-l-tryptophan 1 (RG108) was first identified as inhibitor of DNMT1. Here, 1 analogues were synthesized to understand its interaction with DNMT. The indole, carboxylate, and phthalimide moieties were modified. Homologated and conformationally constrained analogues were prepared. The latter were synthesized from prolinohomotryptophan derivatives through a methodology based amino-zinc-ene-enolate cyclization. All compounds were tested for their ability to inhibit DNMT1 in vitro. Among them, constrained compounds 16-18 and NPys derivatives 10-11 were found to be at least 10-fold more potent than the reference compound. The cytotoxicity on the tumor DU145 cell line of the most potent inhibitors was correlated to their inhibitory potency. Finally, docking studies were conducted in order to understand their binding mode. This study provides insights for the design of the next-generation of DNMT inhibitors.

Identification of novel inhibitors of DNA methylation by screening of a chemical library.

In order to discover new inhibitors of the DNA methyltransferase 3A/3L complex, we used a medium-throughput nonradioactive screen on a random collection of 1120 small organic compounds. After a primary hit detection against DNA methylation activity of the murine Dnmt3A/3L catalytic complex, we further evaluated the EC50 of the 12 most potent hits as well as their cytotoxicity on DU145 prostate cancer cultured cells. Interestingly, most of the inhibitors showed low micromolar activities and little cytotoxicity. Dichlone, a small halogenated naphthoquinone, classically used as pesticide and fungicide, showed the lowest EC50 at 460 nM. We briefly assessed the selectivity of a subset of our new inhibitors against hDNMT1 and bacterial Dnmts, including M. SssI and EcoDam, and the protein lysine methyltransferase PKMT G9a and the mode of inhibition. Globally, the tested molecules showed a clear preference for the DNA methyltransferases, but poor selectivity among them. Two molecules including Dichlone efficiently reactivated YFP gene expression in a stable HEK293 cell line by promoter demethylation. Their efficacy was comparable to the DNMT inhibitor of reference 5-azacytidine.

DNA methylation associated with polycomb repression in retinoic acid receptor ß silencing.

Retinoic acid receptor ß 2 (RARß2) is a tumor suppressor gene whose loss of expression is recurrent in prostate cancers. Here we studied the epigenetic mechanisms leading to its stable silencing. First, we characterized all RARß isoforms in 6 human tumor cell lines (prostate DU145, LNCaP, PC3, lung A549, breast Hs578T, and colon HCT116) by RT-PCR and Western blot. We excluded loss of heterozygosity (2D-FISH) and loss of RARa expression, an upstream regulator, as origin of RARß2 silencing. All data concluded to an epigenetic silencing. In agreement, a DNA methylation inhibitor restored its expression. Second RARß2 loss of expression was found associated with different epigenetic profiles in LNCaP and DU145 cells. According to bisulfite sequencing and ChIP analysis, we observed heavy methylation (97%) of the RARß2 promoter with repressive histone mark H3K9me3 in LNCaP. While DNA methylation and polycomb repression are described to be mutually exclusive at CpG-rich promoters, we observed that in DU145, moderate DNA methylation (36%) and H3K9me3 mark were present concomitantly with H3K27me3, a signature of polycomb repression. In summary, we provide new insights on how the RARß2 promoter is silenced, reveal the existence of two distinct repressive chromatin profiles at the same locus, and support a polycomb-mediated epigenetic repression process in prostate cancer.

Rapid synthesis of new DNMT inhibitors derivatives of procainamide.

DNA methyltransferases (DNMTs) are responsible for DNA methylation, an epigenetic modification involved in gene regulation. Families of conjugates of procainamide, an inhibitor of DNMT1, were conceived and produced by rapid synthetic pathways. Six compounds resulted in potent inhibitors of the murine catalytic Dnmt3A/3L complex and of human DNMT1, at least 50 times greater than that of the parent compounds. The inhibitors showed selectivity for C5 DNA methyltransferases. The cytotoxicity of the inhibitors was validated on two tumour cell lines (DU145 and HCT116) and correlated with the DNMT inhibitory potency. The inhibition potency of procainamide conjugated to phthalimide through alkyl linkers depended on the length of the linker; the dodecane linker was the best.

DNA methyltransferase assays.

DNA methyltransferases are important enzymes and their inhibition has many potential applications. The investigation of DNA methyltransferases as well as screening for potential inhibitors requires specialized enzyme assays. In this chapter, we describe three DNA methyltransferase assays, each of them based on a different method: (1) An assay using radioactively labeled AdoMet and biotinylated DNA substrates that is ideal for enzymatic characterization of these enzymes. (2) An assay using bisulfite conversion of in vitro methylated DNA that is ideal to determine details of the methylation pattern introduced by DNA-(cytosine C5)-methyltransferases. (3) A novel fluorescence-coupled, restriction-based assay suitable for high-throughput screening of DNA methyltransferase inhibitors.

C5-DNA methyltransferase inhibitors: from screening to effects on zebrafish embryo development.

DNA methylation is involved in the regulation of gene expression and plays an important role in normal developmental processes and diseases, such as cancer. DNA methyltransferases are the enzymes responsible for DNA methylation on the position 5 of cytidine in a CpG context. In order to identify and characterize novel inhibitors of these enzymes, we developed a fluorescence-based throughput screening by using a short DNA duplex immobilized on 96-well plates. We have screened 114 flavones and flavanones for the inhibition of the murine catalytic Dnmt3a/3L complex and found 36 hits with IC(50) values in the lower micromolar and high nanomolar ranges. The assay, together with inhibition tests on two other methyltransferases, structure-activity relationships and docking studies, gave insights on the mechanism of inhibition. Finally, two derivatives effected zebrafish embryo development, and induced a global demethylation of the genome, at doses lower than the control drug, 5-azacytidine.

Triplex formation on DNA targets: how to choose the oligonucleotide.

Triplex-forming oligonucleotides (TFOs) are sequence-specific DNA binders. TFOs provide a tool for controlling gene expression or, when attached to an appropriate chemical reagent, for directing DNA damage. Here, we report a set of rules for predicting the best out of five different triple-helical binding motifs (TM, UM, GA, GT, and GU, where M is 5-methyldeoxycytidine and U is deoxyuridine) by taking into consideration the sequence composition of the underlying duplex target. We tested 11 different triplex targets present in genes having an oncogenic role. The rules have predictive power and are very useful in the design of TFOs for antigene applications. Briefly, we retained motifs GU and TM, and when they do form a triplex, TFOs containing G and U are preferred over those containing T and M. In the case of the G-rich TFOs, triplex formation is principally dependent on the percentage of G and the length of the TFO. In the case of the pyrimidine motif, replacement of T with U is destabilizing; triplex formation is dependent on the percentage of T and destabilized by the presence of several contiguous M residues. An equation to choose between a GU and TM motif is given.

Triple helix-forming oligonucleotides conjugated to new inhibitors of topoisomerase II: synthesis and binding properties.

Triplex-forming oligonucleotides (TFOs) are among the most specific DNA ligands and represent an important tool for specific regulation of gene expression. TFOs have also been used to target DNA-modifying molecules to obtain irreversible modifications on a specific site of the genome. A number of molecules have been recognized to target topoisomerase II and stabilize double-stranded cleavage mediated by this enzyme thus determining permanent DNA damage. Among these poisons, etoposide (VP16), a 4'-demethylepipodophyllotoxin derivative, is widely used in cancer chemotherapy. In the aim to design DNA site-specific molecules, three analogues of VP16 (1, 2, and 3), recently described (Duca et al. J. Med. Chem. 2005, 48, 596-603), were attached to TFOs, together with a fourth one, of which the synthesis is reported here. Two different oligonucleotides, differing by the length (a 16-mer and a 20-mer), and two different linker arms between the oligonucleotide and the drug were used. The coupling reaction between the drug and the TFO was further improved. For the first time, we also report the synthesis of TFO conjugates bearing two molecules of inhibitor linked to the same oligonucleotide end. In total, 16 new conjugates were synthesized and evaluated for their ability to form triple helices. The loss in triplex stability due to the conjugation of the TFO to compounds that do not interact with DNA is compensated by the presence of the ethylene glycol linker arm. This stabilization effect is more pronounced at the 3' end than at the 5' end. All conjugates form a stable triplex selectively on the DNA target at 37 degrees C and pH 7.2.