Systematic Evaluation of Benchmark G4 Probes and G4 Clinical Drugs using three Biophysical Methods: A Guideline to Evaluate Rapidly G4-Binding Affinity.

G-quadruplex DNA structures (G4) are proven to interfere with most genetic and epigenetic processes. Small molecules binding these structures (G4 ligands) are invaluable tools to probe G4-biology and address G4-druggability in various diseases (cancer, viral infections). However, the large number of reported G4 ligands (>1000) could lead to confusion while selecting one for a given application. Herein we conducted a systematic affinity ranking of 11 popular G4 ligands vs 5 classical G4 sequences using FRET-melting, G4-FID assays and SPR. Interestingly SPR data globally align with the rankings obtained from the two semi-quantitative assays despite discrepancies due to limits and characteristics of each assay. In the whole, PhenDC3 emerges as the most potent binder irrespective of the G4 sequence. Immediately below PDS, PDC-360A, BRACO19, TMPyP4 and RHPS4 feature strong to medium binding again with poor G4 topology discrimination. More strikingly, the G4 drugs Quarfloxin, CX5461 and c-PDS exhibit weak affinity with all G4s studied. Finally, NMM and Cu-ttpy showed heterogeneous behaviors due, in part, to their physicochemical particularities poorly compatible with screening conditions. The remarkable properties of PhenDC3 led us to propose its use for benchmarking FRET-melting and G4-FID assays for rapid G4-affinity evaluation of newly developed ligands.

Constrained G4 structures unveil topology specificity of known and new G4 binding proteins.

G-quadruplexes (G4) are non-canonical secondary structures consisting in stacked tetrads of hydrogen-bonded guanines bases. An essential feature of G4 is their intrinsic polymorphic nature, which is characterized by the equilibrium between several conformations (also called topologies) and the presence of different types of loops with variable lengths. In cells, G4 functions rely on protein or enzymatic factors that recognize and promote or resolve these structures. In order to characterize new G4-dependent mechanisms, extensive researches aimed at identifying new G4 binding proteins. Using G-rich single-stranded oligonucleotides that adopt non-controlled G4 conformations, a large number of G4-binding proteins have been identified in vitro, but their specificity towards G4 topology remained unknown. Constrained G4 structures are biomolecular objects based on the use of a rigid cyclic peptide scaffold as a template for directing the intramolecular assembly of the anchored oligonucleotides into a single and stabilized G4 topology. Here, using various constrained RNA or DNA G4 as baits in human cell extracts, we establish the topology preference of several well-known G4-interacting factors. Moreover, we identify new G4-interacting proteins such as the NELF complex involved in the RNA-Pol II pausing mechanism, and we show that it impacts the clastogenic effect of the G4-ligand pyridostatin.

[Fighting against unexplained sudden death]. / Mort subite, en quête d'une explication.

Sudden cardiac death, mostly related to ventricular arrhythmia, is a major public health issue, with still very poor survival at hospital discharge. Although coronary artery disease remains the leading cause, other etiologies should be systematically investigated. Exhaustive and standardized exploration is required to eventually offer specific therapeutics and management to the patient as well as his/her family members in case of inherited cardiac disease. Identification and establishing direct causality of the detected cardiac anomaly may remain challenging, underlying the need for a multidisciplinary and experimented team.

[Sinus node dysfunction associated with cardiac sarcoidosis: A case report]. / Dysfonction sinusale au cours de la sarcoïdose cardiaque: à propos d'un cas.

INTRODUCTION: Sarcoidosis is a multisystemic granulomatous disease of unknown cause occurring in young adults. Cardiac sarcoidosis patients are at increased risk for atrioventricular blocks and ventricular arrhythmias. Sinus node dysfunction is scarcely reported. OBSERVATION: We report a case of cardiac sarcoidosis revealed by a sinus node dysfunction and focus on cardiac and thoracic imaging to guide diagnosis. CONCLUSION: Sinus node dysfunction may be the first manifestation of cardiac sarcoidosis. In unexplained sinus node dysfunction in young patients, advanced cardiac imaging is a key to cardiac sarcoidosis diagnostic. Early recognition of cardiac sarcoidosis enables to start immunosuppressive treatment and discuss implantable cardioverter defibrillator implantation.

Surface plasmon resonance study of the interaction of N-methyl mesoporphyrin IX with G-quadruplex DNA.

Surface plasmon resonance (SPR) was used to investigate the interaction between N-methyl mesoporphyrin IX (NMM) and different G-quadruplex (G4) topologies. The study was associated with circular dichroism analysis (CD) to assess the topology of the G4s when they interacted with NMM. We demonstrate the high selectivity of NMM for the parallel G4 structure with a dissociation constant at least ten times lower than those of other G4 topologies. We also confirm the ability of NMM to shift the G4 conformation from both the hybrid and antiparallel topologies toward the parallel structure.

Administration of dietary prebiotics improves growth performance and reduces pathogen colonization in broiler chickens.

Dietary prebiotics are thought to be potentially important alternatives to antibiotic growth promoters in poultry production because of their beneficial performance and health effects. The administration of dietary prebiotics has been demonstrated to improve animal health, growth performance, and microbial food safety in poultry production. In this study, we evaluated the effects of Saccharomyces-derived prebiotic refined functional carbohydrates (RFC) with yeast culture on growth performance and gastrointestinal and environmental microbiota when administered in-feed and through drinking water to broiler chickens. Broilers were administered 2 doses of prebiotic in-feed through 42 d of production and prebiotic-treated water in the final 72 h. Administration of prebiotic RFC improved ADG and decreased cecal Campylobacter counts, while the high dose also increased final BW. Additionally, significant main effects of prebiotic RFC dose were observed with the high dose improving ADG and ADFI over the finisher phase and final BW. Although the effects were not significant, the prevalence of Campylobacter in the cecum after feed withdrawal was 17% lower when broilers were administered the high prebiotic dose, and recovery of Campylobacter from litter was up to 50% lower when broilers were administered prebiotic RFC. Our results suggest that co-administration of RFC with yeast culture as a prebiotic can be used to improve growth performance and reduce human foodborne pathogens in poultry.

Influence of the SPR Experimental Conditions on the G-Quadruplex DNA Recognition by Porphyrin Derivatives.

Surface plasmon resonance (SPR) is a powerful technique to study the interactions of ligands with analytes and therefore a number of biosensor surfaces and injection methods have been developed so far. However, many experimental parameters can affect the interactions and consequently the affinity measurements. In particular, the interactions of positively charged analytes (often used for anionic nucleic acids targets) can be influenced by the sensing surfaces (e.g., negatively charged), leading to significant nonspecific interactions as well as regeneration problems. The aim of the present work is to investigate the effect of different parameters, including ionic strength, SPR biosensor (i.e., nature of the surfaces), and the injection method on the recognition of porphyrin G-quadruplex ligands. We demonstrate that the injection method does not influence the affinity whereas the ionic strength and the nature of the surface impact the recognition properties of the porphyrin for the G-quadruplex DNA. We also found that self-assembled monolayer coating surface presents many advantages in comparison with carboxymethylated dextran surface for SPR studies of G-quadruplex DNA/ligand interactions: (i) the electrostatic interaction with charged analytes is less important, (ii) its structure/composition is less sensitive to the ionic concentration and less prone to unspecific adsorption, (iii) it is easily homemade, and (iv) the cost is approximately 10 times cheaper.

[Management of patients with pacemakers or implantable cardioverter defibrillator undergoing radiotherapy]. / Prise en charge des patients porteurs de stimulateurs cardiaques ou défibrillateurs automatiques implantables traités par irradiation.

An increasing number of patients with cardiac implantable electronic devices benefit from radiotherapy, warranting specific collaborative management between both radiation oncologists and cardiologists. Interactions between electromagnetic fields, secondary particles and cardiac implantable electronic devices may result in transient and reversible malfunctions with significant consequences depending on the underlying cardiac pathology and the level of patient's cardiac implantable electronic devices dependency. Numerous international guidelines on patients' management have been proposed and all agree on a total cumulated dose limit at the battery of 5Gy and on the need for an initial as well as repeated evaluation over time, up to 6months after the last radiation. The analysis of the published data revealed relatively rare incidence of significant adverse events. The most recent international guidelines underline the feasibility and safety of radiotherapy for cardiac implantable electronic devices holders, with the need for systematic local protocol in all radiotherapy centers.

Corynebacterium jeikeium pacemaker infection associated with antineutrophil cytoplasmic antibodies: a single positive blood culture could be sufficient for diagnosis.

Corynebacterium jeikeium, a member of the non-diphtheria corynebacteria, has been rarely reported as being responsible for cardiovascular-device infection. Here, we report what is believed to be the first case of C. jeikeium pacemaker infection associated with the presence of proteinase-3 antineutrophil cytoplasmic antibodies. The diagnosis was established based on the positivity of a single positive blood culture and led to pacemaker extraction. This observation highlights the difficulty in the diagnosis of cardiac-device infection in the presence of a single positive blood culture with a fastidious microorganism that could be considered as a contaminant. It also underscores the need for device extraction to ensure healing.

Whole body [(18) F]fluorodeoxyglucose positron emission tomography imaging for the diagnosis of pacemaker or implantable cardioverter defibrillator infection: a preliminary prospective study.

We studied the potential use of [(18) F]fluorodeoxyglucose ((18) F-FDG) whole body positron emission tomography (PET)-computed tomography for the diagnosis of device infection and extension of infection. Twenty-one patients with suspected device infection were prospectively included and compared with 14 controls free of infection. (18) F-FDG uptake on the box and on the leads was visually and quantitatively interpreted (using the maximal standard uptake value). The final diagnosis was obtained either from bacteriological data after device culture (n = 11) or by a 6-month follow-up according to modified Duke's criteria (n = 10). Ten patients finally showed infection on bacteriological study (n = 8) or during follow-up (n = 2). Sensitivity, specificity, positive predictive value and negative predictive value were, respectively, 80%, 100%, 100% and 84.6% on patient-based analysis (presence or absence of infection). They were 100%, 100%, 100% and 100% for boxes, but only 60%, 100%, 100% and 73% for leads. Quantitative analysis could be useful for boxes but not for leads, for which the presence of a mild hot spot was the best criterion of infection. The four false negatives on leads received antibiotics for longer than the six true positives (20 ± 7.2 vs. 3.2 ± 2.3 days, p <0.01). Although the study was not designed for this purpose, management could have been modified by PET results in six of 21 patients. (18) F-FDG PET imaging may be useful for the diagnosis of device infection, and could impact on clinical management. Interpretation of negative cases should be performed with caution if patients have received antibiotics.

[Perspectives in cardiology: evidence of efficacy in atrial fibrillation and hopes in acute coronary syndrome]. / Perspectives en cardiologie : une efficacité démontrée dans la fibrillation atriale, des espoirs dans le syndrome coronaire aigu.

New antithrombotic drugs, antithrombin or anti Xa, will probably be very useful in cardiology. Two directions are interesting: in one hand atrial fibrillation, in which the unmet need concern drugs as effective as vitamine K antagonists but easier to use. On the other hand, in acute coronary syndrome the situation is different, there are many antithrombotic drugs available but there is still a place for innovative drugs which could provide a gain in terms of efficacy, but the hemorrhagic risk must remain acceptable. In atrial fibrillation, the RELY trial, performed in 18,113 patients has demonstrated, as compared to warfarin, a non inferiority of dabigatran at the dose of 110 mg BID and a superiority of dabigatran at 150 mg BID with a reduction of 34% of the primary endpoint, i.e.stroke and systemic embolism.

[Survey into cardiac pacing in the Ile-de-France area for the year 2001: evaluation of indications]. / Enquête sur la stimulation cardiaque en Ile-de-France pour l'année 2001: evaluation des indications.

UNLABELLED: A survey into the implantation of cardiac pacemakers during 2001 in the Ile-de-France area was carried out by the French National Insurance Medical Service in order to evaluate performance in all centres performing more than 10 primary implantations per year. METHODS AND RESULTS: In 2001, 12 centres out of a total of 49 performed less than 50 primary implantations per year, representing 5% of the total regional activity, which was estimated to be 6414 procedures. The remaining 95% of procedures were spread evenly among 8 high-throughput centres (> 200 primary implantations per year) and 29 medium-throughput centres (50 to 200 primary implantations per year). Indications for pacing were analysed retrospectively by a team of regulatory doctors on a sample of 2176 patients with reference to the ACC/AHA/NASPE guidelines. After examination of the medical records, the indication was ranked as being class I, II or Ill (absence of indication). A valid indication was lacking in 8.2% of cases. Sinus node dysfunction represented 74.6% of the non-indications, and this classification had the predictive factors of asymptomatic dysfunction, and treatment with anti-arrhythmic or bradycardic medication. The proportion of class III interventions was significantly lower in the high-throughput centres (5.8 vs 9.9%, p < 0.05). CONCLUSION: 8.2% of primary pacing procedures were not indicated and resulted principally from asymptomatic sinus node dysfunction.

[Long-term evaluation of endocavitary cryoablation of nodal reentry]. / Evaluation à long terme de la cryoablation endocavitaire dans le traitement des réentrées nodales.

Radiofrequency ablation is the reference treatment of refractory nodal reentry. Cryoablation has the advantage of having more modulable effects and minimises the risk of permanent atrioventricular block (AVB). Its immediate efficacy seems comparable to that of radiofrequency ablation but the long-term results are not well known. Endocavitary cryoablation of the slow pathway was undertaken in 26 patients (18 women) with an average age of 47.7 +/- 72.8 years with re-entrant nodal tachycardia refractory to medical therapy. The primary success rate was 92% (24 out of 26). On average, 2.6 +/- 2.2 (1 to 10) cryoablations at - 70 degrees C were delivered and were preceded by 6.4 +/- 4.5 (1 to 16) cryomappings to locate the site of the slow pathway. During cryomapping, 8 episodes of AVB were observed in 6 patients (6 second or third degree), all of which were revertible on rewarming. No cases of permanent AVB were observed. An oesophageal stimulation test of inducibility was performed on the 4th day in 21 patients, 16 of which were not reinducible. During follow-up of 355 +/- 194 days, 22 of the 26 patients (85%) had no recurrence of the arrhythmia. Two of the 24 primary successes had a recurrence, in addition to the two primary failures. Two of the four recurrences occurred in a non-sustained form which was less disabilitating for the patient and the recurrences were controlled in the 4 patients by antiarrhythmic therapy. These results suggest that cryoablation may be a reliable and effective long-term treatment of re-entrant nodal tachycardias. If confirmed in larger series in terms of efficacy and safety, cryoablation could become the treatment of choice of re-entrant nodal tachycardia.

[New energy sources for ablative methods]. / Nouvelles sources d'énergie dans les méthodes ablatives.

Radiofrequency current is the reference energy source for endocavitary ablation of arrhythmias. It is particularly well adapted for the ablation of focal arrhythmogenic substrates such as accessory pathways or foyers of automatism. Technological advances have made the lesions larger but the extension of the indications of percutaneous ablation to more complex substrates such as atrial fibrillation have justified the evaluation of alternative energies. The production of linear transmural lesions or deeper lesions which respect the parietal myocardial architecture and endocardial structure are a challenge for these energies. The capacity of functional mapping specific to cryogenics has provided this energy source with a clinical application for ablation of high risk structures whereas other energies, despite the chronicity of their experimental evaluation, are still at the stage of preliminary clinical trials with the sophisticated catheters in special indications.

Effect of inorganic versus organic selenium on hen production and egg selenium concentration.

A 28-d experiment using 288 Hy-Line W-36 laying hens was conducted to compare sodium selenite (SS) with Se-enriched yeast (SY). The Se from SS or SY was supplemented into a corn-soybean meal basal diet at 0, 0.15, 0.30, 0.60, or 3.00 ppm, and the basal diet was formulated to provide 0.82% lysine and 2,950 kcal/kg of ME. Each treatment was replicated 4 times with 2 cages of 4 hens per cage in each replicate. Hen production was assessed daily, and 2 eggs per replicate were collected every 4 d for whole-egg Se analysis. Albumen quality was assessed at 2 egg storage temperatures (7.2 vs. 22.2 degrees C) with the eggs collected on d 24 and 28, respectively. The percentage of dirty and cracked eggs was greater (P < 0.04) in hens fed SY than in those fed SS. Percentage hen-day production was not affected (P > 0.05) by diet. Albumen quality of eggs stored at 22.2 degrees C was improved (P < 0.04) in eggs from hens fed SS, but there was no difference (P > 0.05) in albumen quality of eggs stored at 7.2 degrees C. Egg weight was linearly increased (P < 0.01) by SY. Whole-egg Se levels were linearly increased (P < 0.01) as dietary Se level increased for both sources of Se, but eggs from hens fed SY had higher (P < 0.01) Se concentrations than those fed SS. The results from this experiment indicate that percentage hen-day production is not affected by Se source, and that SY increases egg Se concentrations more than SS.

A comparison of two sources of phytase in liquid and dry forms in broilers.

Research with corn-soybean meal diets was conducted to compare phytase sources in commercial broilers. A Ca to nonphytate P (nPP) ratio of 2.5:1 was maintained in all diets. Experiments 1 and 2 were conducted from d 4 to 13 (experiment 1) or d 9 to 23 post-hatching (experiment 2) in batteries. The 10 treatments used in both experiment were: Diets 1 to 4 = 0.20, 0.25, 0.30, or 0.35% nPP; Diets 5 to 7 = diet 1 plus 100, 200, or 300 phytase units/kg of diet from Natuphos (NAT); and Diets 8 to 10 = diet 1 plus 100, 200, or 300 phytase units/ kg of diet from Ronozyme (RON). As nPP levels increased, daily gain (ADG), feed intake (ADFI), gain:feed, and toe and tibia ash percentage were linearly increased (P < 0.06) in experiments 1 and 2. Incremental addition of phytase, regardless of source, linearly increased (P < 0.07) ADG and ADFI in experiment 1. Broilers fed NAT had higher (P < 0.07) toe ash percentage in experiment 1 and 2, and higher (P < 0.02) ADG and ADFI in experiment 2 than those fed RON. In experiment 3, 3,360 broilers were used to test 2 dry phytase products from 0 to 41 d posthatching in a 3-phase feeding program. The treatments were: Diet 1) adequate Ca and nPP; Diet 2) nPP reduced by 0.20%; Diets 3 to 5 = diet 2 plus 300, 500, or 750 phytase units/kg of diet from NAT; and Diets 6 to 8 = Diet 2 plus 300, 500, or 750 phytase units/kg of diet from RON. Broilers fed the adequate Ca and nPP diet had improved ADG and ADFI overall, and tibia ash weight and percentage in all growth phases (P < 0.03) compared with those fed the reduced Ca and nPP diets. Overall, ADG and ADFI were linearly increased (P < 0.05) by incremental phytase addition in experiment 3. Both NAT and RON produce similar growth and bone ash traits in commercial broilers.

[External electrical cardioversion of atrial arrhythmia: predictive criteria of success]. / Cardioversion électrique externe des troubles du rythme atriaux: critères prédictifs de succès.

AIM: Supraventricular arrhythmia is a major public health problem because of its prevalence and clinical consequences. The first step of the treatment usually consists in restoring sinusal rhythm. The aim of this study is to evaluate results and predictive factors of success of electrical cardioversion. METHODS: We studied a series of 143 consecutive electric cardioversion preformed in 131 French patients. RESULTS: The rate of successful direct current cardioversion was 91.2%. Negative predictive factors are the height body mass index and the age of arrhythmia. Atrial flutter is a predictive factor of success. These results agree with published results. Our study highlights the interest of some nonantiarrhythmic drugs received by the patient during the period before the direct current cardioversion. Thus, a spironolactone treatment appears to be a new predictive factor of the success of electrical cardioversion (success in patients treated with spironolactone: 100% vs 89% without, P = 0.04). CONCLUSIONS: Our results agree with usual predictive factors of the success of cardioversion. Nevertheless, a new approach is that of the positive effect of spironolactone on cardioversion. A prospective randomized study is necessary to confirm this result.

[Predictive criteria of early recurrence of atrial arrhythmia after reduction by electrical cardioversion]. / Critères prédictifs de récidive précoce d'un trouble du rythme atrial après réduction par choc électrique externe.

The management of atrial arrhythmias aims not only to restore sinus rhythm but also to maintain it. Ten to thirty per cent of patients have early recurrence of atrial arrhythmias, the treatment of which remains empiric. The aim of this study was to define factors predictive of early recurrence of atrial arrhythmias and the consequences on the length of hospital stay. A series of 131 patients who underwent reduction of atrial arrhythmias by electrical cardioversion was studied retrospectively. A recurrence within 24 hours was observed in 12.2% of the patients. These recurrences significantly increased the length of hospital stay (6.8+/-6.3 versus 3.6+/-3.8 days, p=0.005). This study confirms two previously reported results with respect to more long-term recurrences. In the "early recurrence" group, the duration of the atrial arrhythmia was longer (p=0.003) and there were fewer treatments with amiodarone (p=0.03). In addition, original results were obtained. In the "early recurrence" group, the patients were more often treated with furosemide (p=0.02), class Ic antiarrhythmics (p=0.007) or anaesthetised with thiopental (p=0.002) than patients without early recurrences. Experimental data explain these results. However, they require confirmation by a prospective randomised trial.

Reproducibility of the ventricular synchronization parameters assessed by multiharmonic phase analysis of radionuclide angiography in the normal heart.

Radionuclide angiography (RNA) permits analysis of contractility and conduction abnormalities. We determined the parameters of normal ventricular synchronization, assessed the reproducibility of the technique, and compared first harmonic (1H) and third harmonic (3H) analysis. Forty-four normal subjects (28 men and 16 women) were studied. RNA was performed in left anterior oblique (LAO) and left lateral (LL) projections. The onset (To), mean time (Tm), total contraction time (Tt) for right ventricle (RV) and left ventricle (LV), interventricular time (T(RV-LV) = Tm(LV - Tm(RV)) in LAO, and the apex-to-base time (T(a-b)) in LL were measured on the histograms of the time-activity curve. Reproducibility (R) was tested by studying 26 consecutive patients with two successive RNAs. RV starts contracting 25 ms before LV (To(RV) = 29 +/- 37 ms; To(LV) = 54 +/- 39 ms; mean +/- SD) with a 37 ms longer total contraction time. T(RV-LV) is 3 +/- 16 ms. In LL projection, apex and base contract synchronously: T(a-b) = 2 +/- 16 ms. 3H analysis enlarges all duration parameters (To, Tm and Tt), but does not alter synchronization (deltaT(a-b) and deltaT(RV-LV) between 1H and 3H <1%, p = NS). Reproducibility of the duration (T(tLV) and T(tRv)) and synchronization parameters (T(a-b) and T(RV-LV)) is high (R < or = 2.2%). In conclusion, the simultaneous contraction of right and left ventricles and of apex and base can be quantified by RNA phase analysis with high reproducibility. These results, consistent with published electrophysiological data, provide the basis for further non-invasive investigations of ventricular resynchronization in patients with basal electrical or mechanical asynchrony.

[MUSTIC trial]. / L'essai MUSTIC.

The atrio-bi-ventricular pacing has been used for hemodynamic improvement since 1994, and the MUSTIC trial is the first controlled study assessing this concept. It collected 67 patients with severe and stable heart failure with optimised medical therapy, with sinus rhythm and without any traditional indication for pacing. After two periods of three months with blinded randomisation and cross-over, the bi-ventricular pacing mode showed its superiority to the inactive mode concerning all study endpoints, for example with an improvement of the functional capacity of 23% assessed by the 6-minutes-walk test. Thus the MUSTIC trial opens up the way for morbidity and mortality studies.