Dual ontogeny of disease-associated microglia and disease inflammatory macrophages in aging and neurodegeneration

Brain macrophage populations include parenchymal microglia, border-associated macrophages, and recruited monocyte-derived cells; together, they control brain development and homeostasis but are also implicated in aging pathogenesis and neurodegeneration. The phenotypes, localization, and functions of each population in different contexts have yet to be resolved. We generated a murine brain myeloid scRNA-seq integration to systematically delineate brain macrophage populations. We show that the previously identified disease-associated microglia (DAM) population detected in murine Alzheimer's disease models actually comprises two ontogenetically and functionally distinct cell lineages: embryonically derived triggering receptor expressed on myeloid cells 2 (TREM2)-dependent DAM expressing a neuroprotective signature and monocyte-derived TREM2-expressing disease inflammatory macrophages (DIMs) accumulating in the brain during aging. These two distinct populations appear to also be conserved in the human brain. Herein, we generate an ontogeny-resolved model of brain myeloid cell heterogeneity in development, homeostasis, and disease and identify cellular targets for the treatment of neurodegeneration.

Resident Kupffer cells and neutrophils drive liver toxicity in cancer immunotherapy

Immunotherapy is revolutionizing cancer treatment but is often restricted by toxicities. What distinguishes adverse events from concomitant antitumor reactions is poorly understood. Here, using anti-CD40 treatment in mice as a model of T_H1-promoting immunotherapy, we showed that liver macrophages promoted local immune-related adverse events. Mechanistically, tissue-resident Kupffer cells mediated liver toxicity by sensing lymphocyte-derived IFN-γ and subsequently producing IL-12. Conversely, dendritic cells were dispensable for toxicity but drove tumor control. IL-12 and IFN-γ were not toxic themselves but prompted a neutrophil response that determined the severity of tissue damage. We observed activation of similar inflammatory pathways after anti-PD-1 and anti-CTLA-4 immunotherapies in mice and humans. These findings implicated macrophages and neutrophils as mediators and effectors of aberrant inflammation in T_H1-promoting immunotherapy, suggesting distinct mechanisms of toxicity and antitumor immunity.

Combinatorial Single-Cell Analyses of Granulocyte-Monocyte Progenitor Heterogeneity Reveals an Early Uni-potent Neutrophil Progenitor

Granulocyte-monocyte progenitors (GMPs) have been previously defined for their potential to generate various myeloid progenies such as neutrophils and monocytes. Although studies have proposed lineage heterogeneity within GMPs, it is unclear if committed progenitors already exist among these progenitors and how they may behave differently during inflammation. By combining single-cell transcriptomic and proteomic analyses, we identified the early committed progenitor within the GMPs responsible for the strict production of neutrophils, which we designate as proNeu1. Our dissection of the GMP hierarchy led us to further identify a previously unknown intermediate proNeu2 population. Similar populations could be detected in human samples. proNeu1s, but not proNeu2s, selectively expanded during the early phase of sepsis at the expense of monocytes. Collectively, our findings help shape the neutrophil maturation trajectory roadmap and challenge the current definition of GMPs.

Trophic position and individual feeding habits as drivers of differential PCB bioaccumulation in fish populations

Despite PCBs being banned since the 1980's, some European peri-alpine lakes, and consequently their fish populations, are still contaminated by these xenobiotics. We investigated the relative contribution of physiological and trophic factors that could be implicated in fish PCB bioaccumulation in Lake Bourget (France), one of the most contaminated in Europe, by collecting Arctic char (n = 55) and European whitefish (n = 89) from 2013 to 2016. Concentrations of 7 indicator PCBs were 9-168 ng.g w.w^-1 in whitefish and 90-701 ng.g w.w^-1 in Arctic char. The fish trophic positions calculated from δ ¹⁵N values were positively correlated with PCB concentrations (r² = 0.45; p < 0.001). A biomagnification model relying on TP and lipid content of fish was then designed, and it confirmed this result. A Bayesian mixing model based on δ ¹³C and δ ¹⁵N values was used to estimate the relative contribution of preys in the fish diet, which explained a significant proportion of the biomagnification model residuals (i.e., 17%). Zooplankton consumption was negatively correlated with PCB concentrations, whereas consumption of chironomids enhanced the PCB burden in fish. Correction of the biomagnification model for individual diets of fish increased the correlation between the predicted and measured fish PCB contents (R² = 0.71; p < 0.001), highlighting the importance of fish feeding habits in the bioaccumulation process.

Nine-month clinical outcomes in patients with diabetes treated with polymer-free sirolimus-eluting stents and 6‑month vs. 12‑month dual-antiplatelet therapy (DAPT)

BACKGROUND

Diabetes mellitus is known to be associated with worse clinical outcomes in patients with coronary artery disease (CAD) undergoing percutaneous coronary interventions (PCI) with drug-eluting stents (DES). Defining the optimal duration of dual antiplatelet therapy (DAPT) after DES implantation is still under debate. The objective of this subgroup analysis of the all-comers ISAR 2000 registry was to assess the safety and efficacy of a short DAPT (<6 month) versus a longer DAPT (>6 month) in patients with diabetes electively treated with the polymer-free sirolimus-coated ultrathin strut drug-eluting stent (PF-SES).

METHODS

Patients who received the PF-SES were investigated in a multicenter all-comers observational study. The primary endpoint was the 9‑month target lesion revascularization (TLR) rate, whereas secondary endpoints included the 9‑month major adverse cardiac event (MACE) and procedural success rates.

RESULTS

In all, 167 patients were treated with DAPT for ≤6 months (S-DAPT group) and 350 patients underwent DAPT treatment for 12 months (L-DAPT group). There was no significant difference in the overall MACE rate (4.6% vs. 3.1%, p = 0.441), the 9‑month accumulated stent thrombosis rates (0.8% vs. 0.3%, p = 0.51), or the accumulated rate of bleeding complications (5.3% vs. 3.4%, p = 0.341).

CONCLUSION

PF-SES are safe and effective in daily clinical routine with low rates of TLR and MACE in patients with diabetes and stable disease. Our data suggest that extending the duration of DAPT beyond 6 months does not improve MACE or TLR at 9 months in patients with stable CAD (ClinicalTrials.gov Identifier NCT02629575).

Routine measurements of left and right ventricular output by gated blood pool emission tomography in comparison with thermodilution measurements: a preliminary study

The aim of this preliminary study was to evaluate the accuracy of left and right ventricular output computed from a semi-automatic processing of tomographic radionuclide ventriculography data (TRVG) in comparison with the conventional thermodilution method. Twenty patients with various heart diseases were prospectively included in the study. Thermodilution and TRVG acquisitions were carried out on the same day for all patients. Analysis of gated blood pool slices was performed using a watershed-based segmentation algorithm. Right and left ventricular output measured by TRVG correlated well with the measurements obtained with thermodilution (r = 0.94 and 0.91 with SEE = 0.38 and 0.46 l/min, respectively, P < 0.001). The limits of agreement for TRVG and thermodilution measurements were -0.78-1.20 l/min for the left ventricle and -0.34-1.16 l/min for the right ventricle. No significant difference was found between the results of TRVG and thermodilution with respect to left ventricular output (P = 0.09). A small but significant difference was found between right ventricular output measured by TRVG and both left ventricular output measured by TRVG (mean difference = 0.17 l/min, P = 0.04) and thermodilution-derived cardiac output (mean difference = 0.41 l/min, P = 0.0001). It is concluded that the watershed-based semi-automatic segmentation of TRVG slices provides non-invasive measurements of right and left ventricular output and stroke volumes at equilibrium, in routine clinical settings. Further studies are necessary to check whether the accuracy of these measurements is good enough to permit correct assessment of intracardiac shunts.

Source apportionment of PM10, organic carbon and elemental carbon at Swiss sites: an intercomparison of different approaches

In this study, the results of source apportionment of particulate matter (PM10), organic carbon (OC), and elemental carbon (EC) - as obtained through different approaches at different types of sites (urban background, urban roadside, and two rural sites in Switzerland) - are compared. The methods included in this intercomparison are positive matrix factorisation modelling (PMF, applied to chemical composition data including trace elements, inorganic ions, OC, and EC), molecular marker chemical mass balance modelling (MM-CMB), and the aethalometer model (AeM). At all sites, the agreement of the obtained source contributions was reasonable for OC, EC, and PM10. Based on an annual average, and at most of the considered sites, secondary organic carbon (SOC) is the component with the largest contribution to total OC; the most important primary source of OC is wood combustion, followed by road traffic. Secondary aerosols predominate in PM10. All considered techniques identified road traffic as the dominant source of EC, while wood combustion emissions are of minor importance for this constituent. The intercomparison of different source apportionment approaches is helpful to identify the strengths and the weaknesses of the different methods. Application of PMF has limitations when source emissions have a strong temporal correlation, or when meteorology has a strong impact on PM variability. In these cases, the use of PMF can result in mixed source profiles and consequently in the under- or overestimation of the real-world sources. The application of CMB models can be hampered by the unavailability of source profiles and the non-representativeness of the available profiles for local source emissions. This study also underlines that chemical transformations of molecular markers in the atmosphere can lead to the underestimation of contributions from primary sources, in particular during the summer period or when emission sources are far away from the receptor sites.

Cardiac tamponade likely due to candida infection, in an immunocompetent patient

Candida pericarditis is a rare disease described mainly in immunodepressed patients. Here we report the case of a 76-year-old immunocompetent woman who developed a purulent pericarditis 48 hours after pericardiocentesis. Usual etiologies such as cancer or pericardo-oesophageal fistula, were ruled out. Physical examination revealed a sub-mammary mycosis, which could have led to the infection. The early diagnosis and treatment with a combined medical and surgical approach succeeded in a favorable evolution of this case.

Mobilization of CD34+ KDR+ endothelial progenitor cells predicts target lesion revascularization

BACKGROUND

Endothelial lesion and regeneration are critical events in the process leading to in-stent restenosis (ISR) after bare metal stent (BMS) percutaneous coronary intervention (PCI).

OBJECTIVES

To prospectively investigate the relationship between biomarkers reflecting endothelial turnover and the occurrence of ISR.

METHODS

We performed a multicenter prospective observational study that included 156 patients undergoing elective PCI with BMS. Endothelial lesion was assessed by the enumeration of circulating endothelial cells (CECs). Endothelial regeneration was evaluated by enumeration of circulating CD34+ progenitor cells (CD34+ PCs) and CD34+ KDR+ endothelial progenitor cells (EPCs). Measurements were performed before PCI, and 6 and 24 h after PCI. Dynamic changes were evaluated by calculating the delta value of each marker. The primary and secondary endpoints of the study were clinical target lesion revascularizations (TLRs) and major adverse cardiovascular events (MACEs) after 6 months of follow-up.

RESULTS

During follow-up, 28 MACEs were recorded, including 27 TLRs. PCI induced a significant rise in the numbers of CECs, CD34+ PCs, and CD34+ KDR+ EPCs. Baseline, 6-h and 24-h levels of these markers did not differ between patients with and without TLR. The delta percentage of CD34+ KDR+ EPCs was significantly reduced in patients with TLR as compared with patients without TLR (- 0.56 ± 8.1 vs. 2.91 ± 6.2; P = 0.015). In multivariate analysis, the delta percentage of CD34+ KDR+ EPCs independently predicted the occurrence of TLR and MACEs (P = 0.02 and P = 0.014, respectively).

CONCLUSION

The endothelial regenerative response to injury induced by PCI, assessed by CD34+ KDR+ EPCs mobilized among progenitor cells, determines the risk of TLR and MACEs in stable coronary artery disease patients.

[Are patients undergoing coronary angiography well-informed? Prospective evaluation of the effectiveness of written information]

INTRODUCTION

Prior information in the realization of an invasive intervention is crucial. Indeed, the patient has to know theoretically his disease, diagnostic and therapeutic means, but also the risks of the used technique. The habits of information vary many from one center to another, in spite of the proposition of an information leaflet written by the French Society of Cardiology. Our aim was to evaluate the effectiveness of written information for patients hospitalized for coronary arteriography.

METHODS

Among patients hospitalized for realization of a programmed coronarography, a questionnaire was delivered before the information leaflet. The knowledge of the patients was so tested (27 items) before and after the reading of the information sheet (not limited time). The knowledge of the patients concerning coronarography indication, modalities, benefits, possible complications or still later possibilities was informed.

RESULTS

Thirty-four patients were included: all knew hospitalization reason, 86% were men, middle-aged 65 (IC 95% 60-70). Thirty-four percent (15-54) had studied in higher education. Ninety-seven percent had had information before. Only 56% (38-74) were informed about the mode of anesthesia, 36% (19-53) duration, 69% (53-86) the injection of iodine, 44% the risk of allergy, 53% the risk of bruise, 15% of the cardiac risks, 21% the renal risks. Seventy-one percent knew the diagnostic benefits, 44% the possible coronary angioplasty, 17% the eventuality of a bypass surgery. The delivery of the information leaflet did not modify the knowledge on most of these items, in particular the modalities and the profits. The risks were known significantly better for the allergy (P=0.019), the bruise (P=0.018), the cardiac risks (0.001).

CONCLUSIONS

The population benefiting from a coronarography considers to be enough informed. However, knowledge of the modalities, profits and risks is very low. The delivery of the consensual leaflet does not allow improving the situation, except as far as concerned the complications. Better information is so indispensable, not only to obtain a better support of the patient in the treatment, but also to prevent the forensic implications. The improvement of the information must be multifactorial, but usually used means could be not sufficient.

Routinely-feasible multiple biomarkers score to predict prognosis after revascularized STEMI

INTRODUCTION

We assessed the long-term prognostic value of an easy-to-do multiple cardiac biomarkers score after a revascularized acute myocardial infarction (MI) in order to evaluate a multimarker approach to risk stratification, based on routine biomarkers.

MATERIAL AND METHODS

Blood samples from 138 patients hospitalized with acute myocardial infarction and successfully treated by primary coronary intervention (with TIMI 3 flow) were subsequently tested for creatinin level at admittance and then BNP, hsCRP, troponin I from Day 0 to day 7. The primary endpoint was a clinical evaluation comprising: new hospitalization for cardiac reasons, acute coronary events (acute coronary syndrome), and death.

RESULTS

During the median follow-up period of 11.01 months [9.44-12.59], 47 events were recorded. All the following markers were able to predict events: creatinemia on admission (p=0.0057), CRP on day 3 (p, troponin I on day 1 (p<0.001), BNP (p<0.0001) and biological multimarker score (p<0.0001). Clinical events were predicted with a hazard ratio (HR) of respectively 3.30 [2.88-12.30] in BNP Q4 as compared to the three lower quartiles (Q1-3), and 3.15 [2.75-21.00] for the Multimarker approach. The multimarker score was not significantly better than BNP on day 1 alone (p=0.77), troponin on day 1 alone (p=0.43), creatininemia on admission (p=0.19) or CRPhs on day 3 alone (p=0.054). Nevertheless, the Multimarker approach leads to the selection of a smaller, hence more manageable, high-risk population (13% versus 25%).

CONCLUSION

Among 138 subjects admitted for acute MI, and all successfully revascularized, a routinely multimarker approach with BNP, hsCRP, creatininemia, troponin I, is feasible. BNP is the most powerful marker, and this multimarker approach renders additional prognostic information helping to identify patients with high-risk to clinical events.

Can troponin elevation predict worse prognosis in patients with acute pericarditis?

INTRODUCTION

Myopericarditis are common in clinical practice: up to 15% of acute pericarditis have a significant myocardial involvement as assessed by biological markers. This prospective, bicentric study is aimed at describing a myopericarditis population, the clinical and MRI follow-up, and search for prognosis markers.

PATIENTS AND METHODS

Between May 2005 and September 2007, 103 patients hospitalised for acute pericarditis were prospectively enrolled. Physical examination, ECG, echocardiography, biological screening and cardiac MRI, in case of myopericarditis defined as acute pericarditis with troponin I elevation, were performed. Between December 2007 and July 2008, patients were contacted for new clinical and MRI evaluation.

RESULTS

Among the initial population of 103 patients admitted for acute pericarditis, 14 myopericarditis and 38 pericarditis were included. Compared with pericarditis, the myopericarditis group was associated with the following features: younger age (34.9 years [95% CI 28.3-41.2]; p=0.01), ST-segment elevation (nine patients between 14; p=0.03), higher troponin I (7.3 microg/L [95% CI 4.4-10.2]; p<10(-4)) and lower systemic inflammation (CRP peak 38.1mg/L [95% CI 7-69.2]; p=0.01). In the case of myopericarditis, infectious etiologies were predominant (12 patients among 14; p=0.002) and patients stayed longer in hospital (5.8 days [95% CI 4.7-6.8]; p=0.01). Follow-up showed no difference in terms of functional status (p=0.3) and global complications (p=0.9) between paired myopericarditis and pericarditis. Nevertheless, cardiac mortality was higher for myopericarditis (p=0.04). MRI follow-up showed myocardial sequelae without clinical impact.

CONCLUSION

Myopericarditis significantly distinguished from pericarditis. Three years follow-up showed no difference in terms of global complications but a higher cardiac mortality for myopericarditis. MRI myocardial lesions did not develop into symptomatic sequelae.

Recurrent severe acute apical-sparing left ventricular dysfunction in a young woman: don't forget pheochromocytoma

A 35-year-old woman was admitted for second cardiogenic shock. She had no cardiovascular risk factors. Recurrent acute myocarditis was suggested. Recurrent acute myocardial dysfunctions in a young patient suggested pheochromocytoma. Initial trans-thoracic echocardiography showed a typical severe basal and mid-ventricular left ventricular dysfunction but preserved apical contractility. Total CT-scan evidenced a right suprarenal mass advocating for a pheochromocytoma. Biology confirmed the diagnosis of pheochromocytoma. These images illustrate the rare but acute and typical clinical outcomes, and echocardiography findings.

Continuous glucose monitoring as a tool to identify hyperglycaemia in non-diabetic patients with acute coronary syndromes

AIM

To explore the occurrence and the distribution of glucose excursions > 7.8 mmol/l by continuous glucose monitoring (CGM) in non-diabetic patients admitted with acute coronary syndrome (ACS).

METHODS

Twenty-one non-diabetic patients without baseline hyperglycaemia admitted for ACS wore a continuous glucose monitoring system (CGMS) for a median period of 45.6 h. Occurrence and 24-h distribution of time spent with blood glucose > 7.8 mmol/l (TS > 7.8) were retrospectively investigated.

RESULTS

CGMS data disclosed time spent > 7.8 in 17 patients, whereas only seven of them showed at least one capillary blood glucose test value above the threshold for the same time period. Glucose excursions were detectable earlier from CGMS data. Hyperglycaemia was detected most frequently in the morning, more than 2 h after breakfast.

CONCLUSIONS

CGM discloses early and frequent hyperglycaemia in non-diabetic patients with ACS. Intensive glucose monitoring during the morning time period is the most efficient in screening for hyperglycaemia and could be a valuable guide to initiating insulin therapy and to further investigate outcomes in ACS.

[Daily management of acute pericarditis: clinical and paraclinical outcomes, etiological diagnosis]

INTRODUCTION

Acute pericarditis is a frequent hospitalization cause. A prospective, bicentric study aimed at different goals: population description, aetiologies screening, and evaluation of the interest of a coordinated and combined management between cardiologists and internists.

PATIENTS AND METHODS

Between May 2005 and September 2007, all patients admitted for acute pericarditis were prospectively enrolled. Physical examination, ECG, echocardiography, biological screening were performed. Patients were asked to consult both cardiologist and internist, one month later.

RESULTS

Hundred and three patients were enrolled (mean age 43 years). Clinical outcome was classical in 60% of cases. ECG was typical in 59%. Troponin elevation was noted in 30% of patients. CRP was normal at diagnosis in 27% of patients, and increased significantly at first day (P=0.002). Possible cause was identified in 44 patients. In 26 patients (24.3%), precise diagnosis was performed: six cancers, one hemopathy, three connectivities, one EBV and one parvovirus B19 seroconversions, two untreated HIV patients, four inflammatory diseases, three endocrinology troubles, one oesophagitis, one dental sepsis, one amyloidosis, one acute pancreatitis, one declined dialysis indication. Eighteen de novo diagnoses (16.5%) were performed, out of them at least 12 benefited from specific management.

CONCLUSION

Population of patients admitted for acute pericarditis are very heterogeneous. Our co-management between internists and cardiologists aims to diagnose earlier and easier curable diseases. Long-term follow-up remains of great interest, in order to diagnose later other disorders, which remained hidden, and to follow evolution of the population.

Myocardial perfusion imaging and cardiac events in a cohort of asymptomatic patients with diabetes living in southern France

AIMS

To assess the association between abnormal stress myocardial perfusion imaging (MPI) and cardiac events (CE) in asymptomatic patients with diabetes and with > or = 1 additional risk factor. Predictors of abnormal stress MPI were also evaluated.

METHODS

Four hundred and forty-seven consecutive patients who underwent stress MPI were prospectively followed for 2.1 [0.5-4.1] years for the subsequent occurrence of hard CE (myocardial infarction and sudden or coronary death) and soft CE (unstable angina and ischaemic heart failure requiring hospitalization). Re-vascularization procedures performed as a result of the screening protocol were not included in the analysis.

RESULTS

Follow-up was successful in 419 of 447 patients (94%), of whom 71 had abnormal MPI at baseline. Medical therapy was intensified in all subjects and especially in those with abnormal MPI. Twenty-three patients with abnormal MPI underwent a re-vascularization procedure. CEs occurred in 14 patients, including six of 71 patients (8.5%) with abnormal MPI and eight of 348 patients (2.3%) with normal MPI (P < 0.005). Only two patients developed a hard CE and 12 a soft CE. In multivariate analysis, abnormal MPI was the strongest predictor for CEs [odds ratio (OR) (95% CI) = 5.6 (1.7-18.5)]. Low-density lipoprotein cholesterol > or = 3.35 mmol/l [OR (95% CI) = 7.3; 1.5-34.7] and age > median [OR (95% CI) = 6.0 (1.2-28.6)] were additional independent predictors for CE. The independent predictors for abnormal MPI were male gender, plasma triglycerides > or = 1.70 mmol/l, creatinine clearance < 60 ml/min and HbA1c > 8%, with male gender the strongest [OR (95% CI) = 4.0 (1.8-8.8)].

CONCLUSIONS

Asymptomatic patients with diabetes in this study had a very low hard cardiac event rate over an intermediate period. This could be explained by the effects of intervention or by the low event rate in the background population. Randomized studies of cardiac heart disease screening are required in asymptomatic subjects with diabetes to determine the effectiveness of this intervention.

[Surgery of ventricular tachycardia in post-infarction left ventricular aneurysm]

The treatment of post-infarction ventricular tachycardias with antiarrhythmic drug therapy, implantable automatic defibrillators, radiofrequency ablation, also includes different surgical procedures such as endocardial resection of the infarct scar, encircling endocardial ventriculotomy and endocardial cryoablation or thermoexclusion by laser. These procedures may be extensive or limited, guided or not by preoperative mapping. The aim of this review of the literature is to update our knowledge of these different surgical techniques and to define their indications.

[Does symptomatic stable coronary artery disease still exist in France?]

In spite of the continuous growth of myocardial revascularisation techniques, stable angina remains an important clinical burden. In France, and based upon estimates from the European Society of Cardiology and from diverse epidemiological sources, 2 million people are likely to have stable angina. Though primary and secondary prevention are improving, this figure is likely to increase further, in particular because of the constant aging of the population (20% of patients more than 80 years of age have angina), but also because of the epidemics proportions that diabetes mellitus and obesity take.

[Arrhythmogenic effects of non cardiovascular drugs]

Among the unwanted effects of drugs, arrhythmogenic effects are particularly fearsome. Although rare they are serious, and responsible for syncope or sudden death, often linked with torsades de pointe on established long QT. For non cardiovascular drugs, detection is difficult because patients do not undergo systematic cardiological surveillance. Nevertheless understanding the risk, identification of predisposing factors, and consideration of the contra-indications are the rules of prescription, which are even more indispensable when the pathology being treated is benign. In effect, the implicated drugs are mainly anti-histamines, antibiotics, neuroleptics and antidepressants. The pharmaceutical companies, regulatory agencies, and pharmacological surveillance services must recognise the greatest possible risk of a drug, thanks to pre-clinical data, experimental electrophysiology both in vivo (measurement of the QT interval) and in vitro (action potential duration) or even in the elementary channel (essentially analysis of the iKr current). Correlated with clinical data (QT changes, pharmacokinetic interactions), a risk/benefit profile can therefore be established, which is even more demanding when the pathology is benign or when alternative drugs are available.

[Mechanisms of action of antiarrhythmics in cardioversion of atrial fibrillation and atrial flutter]

The mechanisms of action of antiarrhythmic drugs at atrial level are multiple. Antiarrhythmics may act at three levels in the prevention of paroxysmal atrial fibrillation: on the arrhythmogenic atrial substrate, the initiating extrasystoles including those of the pulmonary veins, and in the modulation of the autonomic nervous system. However, there are many modes of initiation which are not well understood so that the preventive role of the antiarrhythmic drugs remains imprecise. Cardioversion of persistent atrial fibrillation has been better analysed in healthy hearts: Class I antiarrhythmics in particular, despite their depressive effects on the conduction which are potentially arrhythmogenic, are beneficial by decreasing the number of reentry circuits, prolonging the atrial refractory period on short cycles and, paradoxically, by increasing the period of excitability in AF. All have a preferential action on anisotropic conduction, especially at the pivotal point of reentry. On the other hand, their role in electrophysiological remodelling in the prevention of immediate recurrences and in pathological atria, remains poorly understood. As for atrial flutter, despite many clinical and experimental studies with antiarrhythmics, the current predominant role of radiofrequency ablation greatly limits the value of these pharmacological studies.

[Continuous nodal reciprocal rhythm and Steinert's disease: treatment by double chamber stimulation. A case report]

We report a case of continuous supraventricular tachycardia in a patient affected by Steinert's myotonic dystrophy. The investigation of this tachycardia showed that there was a "slow-fast" common nodal re-entry, rendered continuous by the existence of significant conduction defects in the fast pathway and the slow anterograde pathway. Implantation of a double chamber cardiac stimulator, necessary for conduction defects present in the basal state in this patient allowed, with the evolution of the conduction defects, the complete eradication of reciprocal rhythm entry, without resorting to ablation.

[Metabolic considerations in the treatment of coronary disease in diabetic patients]

Coronary heart disease represents the first cause of death in diabetic patients. The poor outcome of this ischemic disease is multifactorial. The abnormalities in myocardial energy metabolism encountered by the diabetic heart explain both the ischemic severity and the worsening of reperfusion lesions. The metabolic abnormalities in diabetic heart consist in both an impairment of glucose metabolism (diminished glucose uptake, reduced glycolysis, decreased glucose oxidation...) and an increase in fatty acid oxidation. During ischemia, glucose oxidation is reduced and anaerobic glycolysis becomes the main ATP substrate. Lactate accumulate in myocardial cells, inducing both a metabolic acidosis and an intracellular calcium overload. During reperfusion, intracellular homeostasis is restored very slowly in diabetic heart. Several therapeutic approaches are used to correct these metabolic disturbances. Glucose--insulin--potassium infusion in acute myocardial infarction leads to a significant reduction in the mortality relative risk in diabetic patients (ECLA and DIGAMI studies). The benefit is greater in diabetic patients who where non-insulin-treated prior to ischemia followed by myocardial reperfusion therapy. Others more direct pharmacological approaches improve glucose oxidation during myocardial ischaemia and myocardial reperfusion. The reference drug remains trimetazidine for which one of the fundamental mechanism of action was discovered recently. This specific metabolic, non haemodynamic approach, complete the gold-standard treatment of coronary heart disease in diabetic patients (e.g. aspirin, beta-blockers, ACE inhibitors and statins).

[Results of coronary artery surgery in octogenarians]

Over an 11 year period from January 1990 to December 2000, 3282 patients underwent isolated or combined surgical myocardial revascularisation. In this group, 42 were aged 80 or over (maximum 87 years), 1.3% of the total patient population. The mean age of this subgroup was 81.8 +/- 1.75 years) with a male predominance (61.9%). All patients were autonomous and considered to be in good general and psychological health. Preoperative coronary angiography showed 33.3% of left main stem lesions either alone or associated with a right coronary lesion. The ejection fraction was over 50% in 78.6% of cases. Saphenous vein grafts were used in all but 5 patients who also had left internal mammary artery grafts. Thirteen patients (31%) underwent combined valvular surgery (11 aortic and 2 mitral valve) and 2 patients underwent combined vascular surgery. Three patients were operated as an emergency. A total of 5 patients died in the first 30 postoperative days, a hospital mortality of 11.9%. There were 2 postoperative hemiplegias and 2 cases of renal failure which were aggravated in the postoperative period. The other patients were discharged from hospital with a satisfactory cardiac and functional status. The global mortality was 14% at 3 years and 18% at 5 years. The main bad prognostic factor for survival was the association of aortic valve surgery. In selected octogenarians in good general and psychological health without severe co-morbid conditions, surgical myocardial revascularisation may be considered with an acceptable operative risk.

[Electrocardiographic alternans]

A simple ECG curiosity or a precursor of serious arrhythmia, associated with pericardial effusion or a sign of inotropic alteration, the phenomenon of electrical alternans has intrigued clinicians and research workers in its multiple facets, mechanical and electrical, consequences on PR interval, QRS complex or ventricular repolarisation. As a consequence, the causal mechanisms are very different, but these last few years, a predominant role of calcium flux, especially intracellular, has been demonstrated. Recently, clinical interest in this phenomenon has been revived with the demonstration of micro-alternans of repolarisation, apparently a new marker for the risk of sudden death.

The antiangiogenic factor 16K PRL induces programmed cell death in endothelial cells by caspase activation

We asked whether the antiangiogenic action of 16K human PRL (hPRL), in addition to blocking mitogen-induced vascular endothelial cell proliferation, involved activation of programmed cell death. Treatment with recombinant 16K hPRL increased DNA fragmentation in cultured bovine brain capillary endothelial (BBE) and human umbilical vein endothelial (HUVE) cells in a time- and dose-dependent fashion, independent of the serum concentration. The activation of apoptosis by 16K hPRL was specific for endothelial cells, and the activity of the peptide could be inhibited by heat denaturation, trypsin digestion, and immunoneutralization, but not by treatment with the endotoxin blocker, polymyxin-B. 16K hPRL-induced apoptosis was correlated with the rapid activation of caspases 1 and 3 and was blocked by pharmacological inhibition of caspase activity. Caspase activation was followed by inactivation of two caspase substrates, poly(ADP-ribose) polymerase (PARP) and the inhibitor of caspase-activated deoxyribonuclease (DNase) (ICAD). Furthermore, 16K hPRL increased the conversion of Bcl-X to its proapoptotic form, suggesting that the Bcl-2 protein family may also be involved in 16K hPRL-induced apoptosis. These findings support the hypothesis that the antiangiogenic action of 16K hPRL includes the activation of programmed cell death of vascular endothelial cells.

Developmental changes in apolipoprotein B gene expression in the liver of fetal calves

Changes in apolipoprotein (apo B) gene expression in the liver were determined in fetal calves from 90 to 260 days of intrauterine life. Results were compared with those obtained from the livers of 1-month-old calves and adult cows. By Western blot analysis using a rabbit antiserum to bovine apo B, apo B100 was detected from 90 days of intrauterine life. Apo B100 was shown to be the only form of apo B detected in the liver of fetal calves whatever the gestational age indicating the lack of editing process during the prenatal period. Hepatic apo B contents were stable during intrauterine life and comparable to those of calves and lower than those of cows. Hepatic contents of apo B mRNA increased with the gestational age similarly to total RNA. Values of apo B mRNA at 260 days of intrauterine life were comparable to those in the liver of 1-month-old calves and adult cows. These results suggested that hepatic synthesis of calf apo B during fetal development is specifically regulated at a posttranscriptional level, either by a decrease in the rate of translation and/or by an increase in the rate of intracellular apo B degradation.

Facilitation of L-type calcium currents by diastolic depolarization in cardiac cells: impairment in heart failure

OBJECTIVE

Decay kinetics of the voltage-gated L-type Ca(2+) current (I(CaL)) control the magnitude of Ca(2+) influx during the cardiac action potential. We investigated the influence of changes in diastolic membrane potential on I(CaL) decay kinetics in cardiac cells.

METHODS

Cells were isolated enzymatically from rat ventricles, human right atrial appendages obtained during corrective heart surgery and left ventricles from end-stage failing hearts of transplant recipients. The whole-cell patch-clamp technique was used to evoke I(CaL) by a 100-ms depolarizing test pulse to -10 mV. Conditioning potentials between -80 and 0 mV were applied for 5 s prior to the test pulse.

RESULTS

Depolarizing the cells between -80 and -50 mV prior to the test pulse slowed the early inactivation of I(CaL) both in rat ventricular and human atrial cells. This slowing resulted in a significant increase of Ca(2+) influx. This type of facilitation was not observed when the sarcoplasmic reticulum (SR) Ca(2+) content was depleted using ryanodine which reduced the rate of inactivation of I(CaL), or when Ba(2+) replaced Ca(2+) as the permeating ion. Facilitation was favored by intracellular cAMP-promoting agents that, in addition to increasing current peak amplitude, enhanced the fast Ca(2+)-dependent inactivation of I(CaL). Facilitation was impaired in atrial and ventricular human failing hearts.

CONCLUSION

Decay kinetics of I(CaL) are regulated by the diastolic membrane potential in rat and human cardiomyocytes. This regulation, which associates slowing of I(CaL) inactivation with reduced SR Ca(2+) release and underlies facilitation of Ca(2+) channels activity, may have profound physiological relevance for catecholamines enhancement of Ca(2+) influx. It is impaired in failing hearts, possibly due to lowered SR Ca(2+) release.

Dietary coconut oil affects more lipoprotein lipase activity than the mitochondria oxidative capacities in muscles of preruminant calves

The presence of coconut oil in a milk replacer stimulates the growth rate of calves, suggesting a better oxidation of fatty acid in muscles. Because dietary fatty acid composition influences carnitine palmitoyltransferase I (CPT I) activity in rat muscles, this study was designed to examine the effects of a milk replacer containing either tallow (TA) or coconut oil (CO) on fatty acid utilization and oxidation and on the characteristics of intermyofibrillar (IM) and subsarcolemmal (SS) mitochondria in the heart and skeletal muscles of preruminant calves. Feeding CO did not affect palmitate oxidation rate by whole homogenates, but induced higher palmitate oxidation by IM mitochondria (+37%, P < 0.05). CPT I activity did not significantly differ between the two groups of calves. Heart and longissimus thoracis muscle of calves fed CO had higher lipoprotein lipase activity (+27% and 58%, respectively; P < 0.05) but showed no differences in fatty acid binding protein content or activity of oxidative enzymes. Whatever the muscle and the diet, IM mitochondria had higher respiration rates and enzyme activities than those of SS mitochondria (P < 0.05). Furthermore, CPT I activity of the heart was 28-fold less sensitive to malonyl-coenzyme A inhibition in IM mitochondria than in SS mitochondria. In conclusion, dietary CO marginally affected the activity of the two mitochondrial populations and the oxidative activity of muscles in the preruminant calf. In addition, this study showed that differences between IM and SS mitochondria in the heart and muscles were higher in calves than in other species studied so far.

[Electrophysiologic and anatomic atrial remodeling: an atrial rhythmic cardiomyopathy]

In 1995, Wijffels and Alessie, using a curious goat model of atrial fibrillation, introduced the concept of atrial remodelling. The classical atrial substrate (anatomopathological-dilatation and hypokinesis-, and electrophysiological-short refractory periods and decreased conduction-), appeared not only to be one of the causes of atrial fibrillation but also the consequence of atrial fibrillation itself, the mechanism being a vicious circle. In addition to ventricular rhythmic cardiomyopathy, responsible for cardiac failure, the concept of atrial rhythmic cardiomyopathy with the same mechanical and electrophysiological consequences, has developed. These changes, characterised mainly by calcium overload associated with cellular hibernation and differentiation, have not been totally elucidated but have already renewed the physiopathology of atrial fibrillation.

Pharmacological manipulation of Ins(1,4,5)P3 signaling mimics preconditioning in rabbit heart

Recent evidence revealed biphasic alterations in myocardial concentrations of the second messenger inositol (1,4,5)-trisphosphate [Ins(1,4,5)P3] with ischemic preconditioning (PC), i.e., increase during brief PC ischemia and decrease early during sustained test occlusion. Our aim was to determine whether an agonist and an antagonist of Ins(1,4,5)P(3) signaling (D-myo-inositol-1,4,5-trisphosphate hexasodium salt [D-myo-Ins(1,4, 5)P3] and 2-aminoethoxydiphenyl borate (2-APB), respectively), given such that they mimic this biphasic profile, would mimic infarct size reduction with PC. To test this concept, isolated, buffer-perfused rabbit hearts received no intervention (control), ischemic PC, D-myo-Ins(1,4,5)P3, D-myo-Ins(1,4,5)P(3) + PC, 2-APB, or 2-APB + PC. All hearts then underwent 30-min coronary occlusion and 2 h reflow, and infarct size was delineated by tetrazolium staining. In addition, the effects of D-myo-Ins(1,4,5)P3 and 2-APB on Ins(1,4,5)P3 signaling were evaluated in isolated fura 2-loaded rat cardiomyocytes. Mean infarct size was reduced with PC and in all D-myo-Ins(1,4,5)P3- and 2-APB-treated groups versus control (59 and 42-55%, respectively, vs. 80% of myocardium at risk, P < 0.05). Thus pharmacological manipulation of Ins(1,4,5)P3 signaling mimics the cardioprotection achieved with ischemic PC in rabbit heart.

Effects of dietary coconut oil on fatty acid oxidation capacity of the liver, the heart and skeletal muscles in the preruminant calf

The oxidative capacity of the liver, the heart and skeletal muscles for fatty acids were investigated in preruminant calves fed for 19 d on a milk-replacer containing either coconut oil (CO, rich in 12:0) or tallow (rich in 16:0 and 18:1). Weights of the total body and tissues did not differ significantly between the two groups of animals but plasma glucose and insulin concentrations were lower in the CO group. Feeding on the CO diet induced an 18-fold increase in the hepatic concentration of triacylglycerols. Rates of total and peroxisomal oxidation of [1-14C]laurate, [1-14C]palmitate and [1-14C]oleate were measured in fresh tissue homogenates. Higher rates of total oxidation in liver homogenate and of peroxisomal oxidation in liver, heart and rectus abdominis muscle homogenates were observed with laurate used as substrate. Furthermore, the relative contribution of peroxisomes to total oxidation was 1.9-fold higher in the liver and in the heart with laurate than with oleate or palmitate. Finally, the peroxisomal oxidation rate of oleate was 1.5-fold higher in the hearts of calves fed on the CO diet. Whatever the tissue, citrate synthase (CS, EC 4.1.3.7) and cytochrome c oxidase (COX, EC 1.9.3.1) activities were similar between the two groups of calves but the COX: CS activity ratio was lower in the liver of the CO group. In conclusion, laurate is better catabolized by peroxisomes than long-chain fatty acids, especially in the liver. Elongation of lauric acid after partial oxidation might explain the hepatic triacylglycerol accumulation in calves fed on the CO diet.

A "dysautonomic" head-up tilt test pattern in elderly patients with neurocardiogenic syncope

The characteristics of neurocardiogenic syncope (NCS) in elderly patients remain unclear. We compared the hemodynamic profiles of young and older patients with consecutive and positive head-up tilt tests (HUT). Continuous, noninvasive, and reliable monitoring of arterial pressure (AP) and heart rate (HR) was done throughout 46 consecutive positive HUTs of symptomatic patients. The population (12-82 years old) was divided into two groups: younger patients, Y (n = 25, < or = 65 years), and older patients, O (n = 21). Changes in AP and HR after the first minute of tilting, during the stable orthostatic phase and during syncope were compared. Except for systolic pressure, baseline hemodynamic parameters were similar in Y and O. No difference appeared in the mean time elapsed before syncope (19+/-9 vs 22+/-2 min). Asymptomatic hypotension was observed, only in O, 1 minute after tilting, followed by a progressive fall in the mean AP before syncope (0+/-0.9 vs -1+/-0.7 mmHg/min) without HR increase (0.7+/-1 vs 0+/-0.6 beats/min). This pressure slope was strongly related to age (r = 0.54, P < 0.001). Hemodynamic recording during HUT identifies a dysautonomic pattern in elderly patients with NCS and the abnormal AP/HR responses to orthostasis may be a feature specific to this population. Although the central mechanism of NCS is common to all ages, the age-related characteristics of the trigger event may indicate the need for specific management at different ages.

[Electrocardiographic aspects of the pathology of the bundle of His]

The ECG appearances of His bundle pathology are very variable and endocavitory recordings are often required to confirm the diagnosis which may be suspected by close analysis of the surface ECG. Truncular AVB is a serious condition as the block is infranodal but with a supraventricular and therefore a narrow QRS complex: it may be median with a double His potential or proximal and distal, which are more difficult to diagnose. Hisian extrasystoles are particularly polymorphic, either overtly, suggesting successively atrial and ventricular extrasystoles, or masked with deceptive pseudo-1st or 2nd degree atrioventricular block. More rarely, hisian tachycardias complicating congenital heart disease in children are observed, particularly in the postoperative period.