A novel weighted hybrid clinical and electrocardiographic score to predict the origin of outflow tract ventricular arrhythmias: a multicenter study

Funding Acknowledgements

Type of funding sources: None.

Background

To correctly predict the outflow tract ventricular arrhythmia (OTVA) site of origin (SOO) before the ablation is still a procedural major step, having important implications for correct patient counseling, ablation planning, and periprocedural complication evaluation. Although multiple ECG criteria have been proposed for predicting OTVA SOO, their accuracy and usefulness are still limited as recently (1).

Purpose

The present study sought to prospectively evaluate the accuracy of a previously published Hybrid Score (HS) for prediction of OTVAs with LVOT origin. Besides, multiple ECG measurements of patients with V3 precordial transition (V3PT) OTVA were analyzed to identify potential variables useful to improve the accuracy of the HS (2).

Methods

Consecutive patients (n=105) referred for OTVA ablation were prospectively enrolled from three referral centers. Vascular access and first-mapped ventricle were decided based on the previously published HS, which includes ECG (R/S precordial transition) and clinical information (age, hypertension, and gender). Surface ECGs during the OTVA were analyzed by two independent electrophysiologists to compare the discriminative performance of HS and previous published ECG-alone criteria, to assess their inter-observer variability and to identify potential variables useful to improve the proposed model.

Results

Of the 105 VAs, 70.5% had an RVOT origin and 29.5% an LVOT origin. HS achieved a correct prediction in 90% patients. This rate dropped to 75% in the subgroup of patients with V3PT OTVA. The correct prediction rate of the other ECG-alone criteria in the whole population ranged from 74 to 82% and from 41 to 76% in V3PT patients, and their Cohen’s Kappa coefficient for inter-observer variability assessment ranged from 0.63 to 0.81. R-wave amplitude in V3 was the best ECG parameter for discriminating LVOT origin in V3PT patients. When this parameter was incorporated in the novel Weighted Hybrid Score (WHS) (Figure 1), it correctly classified 99 (94.2%) patients (90% sensitivity, 96% specificity, AUC: 0.97). The WHS discriminatory capacity was maintained in V3PT subgroup, (87% sensitivity, 91% specificity AUC: 0.95). WHS showed a Cohen’s kappa coefficient of 0,82. Finally, WHS was validated in an additional population of 97 patients with OTVAs referred for catheter ablation from three additional external centers; in this testing sample the WHS correctly predicted the SOO in 90% patients and proved to have 89% sensitivity and 90% specificity (AUC: 0.94) for a score ≥2 to predict a LVOT origin.

Conclusions

The novel simple-to-use WHS proved to accurately anticipate the PVC’s SOO and can be introduced in clinical practice for choosing the first chamber to map.

Are there sex differences in patients with syncope and bundle branch block?

Background

In the last years a substantial effort has been made to improve the understanding of the sex-differences in cardiovascular disease. However, no studies have examined differences in presentation and outcomes between men and women presenting with syncope and bundle branch block (BBB).

Aim

To determinate if there are sex-specific differences in the characteristics and outcomes of syncope in patients with BBB

Methods

Cohort study carried out in a tertiary hospital that is a reference center for syncope from January 2008 to February 2021. Patients (p.) with BBB and syncope of unknown origin after the initial evaluation without direct indication of an ICD were included. They were managed according to the current ESC guidelines. All patients underwent to an EPS and an ILR was implanted if it was not diagnostic.

Results

374p. were included (75±1 y. o; 135 (36%) female). Mean follow up was 2.3±1.6 y.o. No differences in baseline characteristics where found comparing both groups, except that LBBB was more prevalent in female and RBBB in male (Figure 1A). EPS and ILR diagnostic yield was 44%/44% respectively in females and 50% /40% in males (p=ns). However, basal HV interval in EPS was significant shorter in females (Figure 2A). In the multivariate analyses female sex was associated with a significant lower risk of AV block (Figure 1B), and with a trend of less need of a pacemaker implantation (PM) (53% in females, 60% in males) (Log-rank 0.1) (Figure 2B). No significant differences in recurrences neither in mortality rate were found.

Conclusions

Female patients with syncope and BBB have lower risk of AV block compared to males, and only half of them required a pacemaker implantation. A strategy of direct PM implantation should be avoided, specially in woman.

Funding Acknowledgement

Type of funding sources: None. Figure 1Figure 2

Evaluation of ventricular tachycardia inducibility after implementation of a standardized programmed ventricular stimulation protocol in patients with repaired Tetralogy of Fallot

Introduction

The electrophysiologic (EP) evaluation with programmed electrical stimulation (PVS) is generally recommended in patients with repaired Tetralogy of Fallot and additional risk factors for sudden cardiac death. Nevertheless, different PVS protocols have been described. The aim of our study was to evaluate the differences in ventricular tachycardia (VT) inducibility of patients with TOF after the implementation of a standard PVS protocol in the EP laboratory of a Congenital Heart Disease reference center.

Methods

All patients with repaired TOF who underwent an EP study with PVS between January 2001 and October 2020 were included. The new standardized PVS protocol was performed in 2 ventricular sites (apex and outflow tract) with 3 drive trains (cycle lengths 400, 500 and 600ms) and up to 3 extrastimuli. In absence of VT induction, the protocol was repeated under isoprenaline infusion. This new protocol was implemented since January 2012. Non protocolized PVS studies before 2012 were defined as “Non-standardized”. Baseline clinical information about symptoms and previous arrhythmias was recorded as well as electrocardiogram, echocardiogram and cardiac MRI parameters. Finally, the follow-up events (ICD implantation, sudden cardiac death, global mortality, arrythmias and ICD therapies) were also retrospective recorded.

Results

A total of 154 EP studies with PVS were performed in 128 patients with repaired TOF. 31 of them were performed before the 1st January 2012 (non-standardized PVS) and 112 were performed with the new standardized protocol. The median follow-up was 6,5 years. Both groups had similar baseline characteristics except LVEF and RVEF, that were lower in the “Non-standardized PVS” group. There were no differences between the ventricular tachycardia inducibility of both protocols (22,3% vs 33,3%; p=0,162). The risk factors for VT inducibility were the QRS length (184,46ms vs 169,34 ms; p=0,038), the RVEF (36,25% vs 43,79; p=0,0007), the presence of ventricular ectopia (VE) (38,5% vs 20,0%; p=0,024) and previous VT (35,9% vs 13,9%; p=0,003). VT induction during EP study was related with ICD implantation (71,8% vs 21,7%, p≤0,001), VT (30,8% vs 20%, p<0,001) and all kind of arrythmias (VT, non-sustained VT, VE and auricular flutter) (41% vs 21,7%, p=0,005) during follow-up. A total of 6 deaths (1 in the group with induced VT and 5 in the group with non-induced VT) were recorded.

Conclusions

The implementation of a standardized and more complete PVS protocol in patients with repaired TOF has not shown differences in the experience of our center. The risk factors for VT inducibility were the QRS length, the RVEF, the presence of ventricular ectopia and previous VT, which have also been reported as risk factors for sudden cardiac death in previous studies. The presence of VT induction entailed more ICD implantation and more arrythmias at follow-up.

Funding Acknowledgement

Type of funding sources: None.

Differences in ventricular tachycardia inducibility in patients with Tetralogy of Fallot depending on the clinical indication for the electrophysiologic study

Introduction

The arrhythmic risk stratification of patients with repaired Tetralogy of Fallot (TOF) is still controversial. The performance of an electrophysiologic (EP) study before pulmonary valve replacement (PVR), regardless of patient's risk factors, is an extended practice in some centers that is not recommended in current guidelines. The aim of our study was to explore the differences in ventricular tachycardia (VT) inducibility in patients with TOF during programmed ventricular stimulation (PVS) depending on the clinical indication.

Methods

All patients with repaired TOF who underwent an EP study with PVS between January 2001 and October 2020 were included. EP studies performed in the context of ventricular or supraventricular tachycardia ablations that had been previously diagnosed were excluded. We defined two clinical scenarios for performing the EP study: pre-PVR (performed previous to pulmonary valve replacement) or diagnostic EP study (performed due to high risk symptoms which included palpitations, syncope or presyncope). Baseline clinical information, electrocardiogram, echocardiogram and cardiac MRI parameters were retrospective recorded.

Results

A total of 139 EP studies with PVS were included; 87 in the pre-PVR group and 52 in the diagnostic EP study group. There was a greater incidence of palpitations, syncope and presyncope in the “Diagnostic EP study” group. Moreover, there were statistical significant differences in right ventricle dimensions and function between groups. The repair surgical approach was similar in both groups. It was detected a statistical significant difference in VT induction between the pre-PVR group and the diagnostic indicated group (16,1% vs 34,6%, p=0,012).

Conclusions

Differences in VT induction are observed during PVS performing in TOF patients depending on the clinical indication. Symptomatology is an important parameter that must be taken into account in order to decide whether to perform an EP study in this population.

Funding Acknowledgement

Type of funding sources: None.

First Vs Recurrent Syncope In Patients With Structural Heart Disease Or Bundle Branch Block

Funding Acknowledgements

Type of funding sources: Public hospital(s). Main funding source(s): Hospital Universitari Vall d"Hebron - Vall d"Hebron Institut de Recerca. CIBERCV

BACKGROUND

Patients with structural heart disease (SHD) or bundle branch block (BBB) are at high risk of having an arrhythmic syncope (AS).  In patients with recurrent syncope episodes (RSE)  complete work-up including electrophysiological study (EPS) and/or implantation of a loop recorder (ILR) is recommended, however patients with their first episode may also be at risk of an AS.

AIM

To determinate if the patients with SHD or BBB with a single syncope episode (SSE) are at high risk of having an AS and compare it with patients with recurrent episodes (RSE).

METHODS Cohort study carried out in a tertiary hospital that is a reference centre for syncope. From January 2008 to August 2020 patients with SHD or BBB with syncope of unknown origin after the initial evaluation and without direct indication of an ICD were included. They were managed according the current ESC guidelines.

RESULTS

417patients were included  (74 ±11 y. o; 39% female). Mean follow up was 2.5 ±1 y. 223 patients were diagnosed from an AS [113 (53%) in SSE group and 110 (54%) in RSE group, p = 0.9], 210 were due to bradyarrhythmia (AV block or sinus arrest). No differences in baseline characteristics where found comparing both groups, except that BBB was slightly more prevalent in patients with RSE (81% vs 90%, p = 0.01) (FIGURE- PANEL A). Risk of AS was 53% in patients with SE and 54% (p = 0.9). RSE were not associated with an increased risk of AS in univariate analyses (OR 1.01 IC95% 0.7-1.5) neither in the multivariate (FIGURE- PANEL B). EPS and ILR diagnostic yield was 45% / 32% respectively in SSE group and 44% / 33% in RSE group (p = 0.8) (FIGURE - PANEL C).  After appropriate treatment, recurrence syncope rate was 10% in SSE group and 9% in RSE group (p = 0.8). No significant differences in mortality rate were found.

CONCLUSIONS

Patients with SHD or BBB and single syncope episode are at a high risk of having AS, and similar to those with RSE. EPS and ILR offer a similar diagnostic yield in both groups. Complete syncope work-up must be recommended in these patients despite having had only a single episode. Abstract Figure

Neurohormonal activation induces intracellular iron deficiency and mitochondrial dysfunction in cardiac cells

Background

Iron deficiency (ID) is common in patients with heart failure (HF) and is associated with poor outcomes, yet its role in the pathophysiology of HF is not well-defined. We sought to determine the consequences of HF neurohormonal activation in iron homeostasis and mitochondrial function in cardiac cells.

Methods

HF was induced in C57BL/6 mice by using isoproterenol osmotic pumps and embryonic rat heart-derived H9c2 cells were subsequently challenged with Angiotensin II and/or Norepinephrine. The expression of several genes and proteins related to intracellular iron metabolism were assessed by Real time-PCR and immunoblotting, respectively. The intracellular iron levels were also determined. Mitochondrial function was analyzed by studying the mitochondrial membrane potential, the accumulation of radical oxygen species (ROS) and the adenosine triphosphate (ATP) production.

Results

Hearts from isoproterenol-stimulated mice showed a decreased in both mRNA and protein levels of iron regulatory proteins, transferrin receptor 1, ferroportin 1 and hepcidin compared to control mice. Furthermore, mitoferrin 2 and mitochondrial ferritin were also downregulated in the hearts from HF mice. Similar data regarding these key iron regulatory molecules were found in the H9c2 cells challenged with neurohormonal stimuli. Accordingly, a depletion of intracellular iron levels was found in the stimulated cells compared to non-stimulated cells, as well as in the hearts from the isoproterenol-induced HF mice. Finally, neurohormonal activation impaired mitochondrial function as indicated by the accumulation of ROS, the impaired mitochondrial membrane potential and the decrease in the ATP levels in the cardiac cells.

Conclusions

HF characteristic neurohormonal activation induced changes in the regulation of key molecules involved in iron homeostasis, reduced intracellular iron levels and impaired mitochondrial function. The current results suggest that iron could be involved in the pathophysiology of HF.

Scar and arrhythmic isthmus characterization in patients with D-TGA treated with atrial switch surgery using a new high density mapping grid catheter

Introduction

Patients with D- transposition of the great arteries (TGA) treated with Senning or Mustard surgeries have several atrial scars that predispose them to develop atrial tachycardias (AT). Identification of scar zones and possible arrhythmic isthmus in voltage mapping will help to guide the ablation.

Aim

To describe the feasibility of using a specific mapping catheter to identify possible arrhythmic isthmus in this set of patients.

Methods

Prospective observational study in patients with history of SVT and atrial switch surgery, that underwent electrophysiologic study (EP) and electroanatomic (EA) mapping with a new 8Fr deflectable, multipoint wavefront-activation-orientation independent Grid catheter, in a third level hospital since April 2018 until January 2020, with medium-term follow-up.

Results

A total of 9 EPs were performed in 8 patients (3 (37,5%) Female, median age 35.2 y.o. (IQI 29,2–37,6)). Figure 1A shows an example of an activation and substrate mapping. Figure 1B shows the localization and percentage of scar identified in both atria. A total of 7 tachycardias were induced. In this, an arrhythmogenic isthmus was identified and in all patients at least one non-arrhytmogenic isthmus was documented. Figure 1C shows anatomical and electrophysiological characteristics of the isthmus. Arrhythmogenic isthmus had slower conduction velocity than non-arrhytmogenic (mean 0,31m/s (IQI 0,14–0,63) vs 0,94 m/s (IQI 0,81–1,24) p=0.02) and fractionated potentials were detected more frequently (100% vs 55% p=0.05)

Conclusion

EA mapping with a new a multipoint, high-definition, Grid Cather allows the identification and electrophysiological characterization of arrhythmogenic and non-arrhytmogenic isthmus in patients with TGA treated with atrial switch surgery.

Figure 1

Funding Acknowledgement

Type of funding source: Public hospital(s). Main funding source(s): Hospital Universitari Vall d'Hebron. VHIR

P921Feasibility of multipoint, high-definition mapping with grid cathether of SVTs in patients with D-Transposition of the great arteries treated with atrial switch surgery

Introduction

 Patients with D-transposition of the great arteries (TGA) treated with Senning or Mustard surgery develop supraventricular tachycardias (SVTs) that require treatment with ablation. The use of multipoint, high-density, wavefront-activation-orientation independent mapping catheters hasn’t been reported in literature.

Purpose

To describe the feasibility of using a specific mapping catheter in SVTs in this set of patients.

Methods

Prospective observational study in patients with history of SVT and atrial switch surgery, that underwent EP study and electroanatomic (EA) mapping with a new 8Fr deflectable, multipoint (16 equidistant electrodes along 4 splines), with magnetic sensor, wavefront-activation-orientation independent catheter, in a third level hospital since April 2018 until May 2019, with medium-term follow-up. 

Results

A total of 8 EPS (electrophysiologic studies) were performed in 7 patients (clinical data in Table 1). One patient had a tachycardia recurrence, accounting for a second EPS. The pulmonary venous atrium (PVA) was mapped in all procedures, whereas the systemic venous atrium (SVA) was mapped only in 75% of them, A total of 15 EA maps were obtained, with a ratio of 1.9 maps/patient, and an average of 20 375 ± 13 045 total points per patient. In all cases, PVA mapping was performed via retrograde transaortic approach, without transbaffle puncture. Tachycardia was induced in 5 out of 8 procedures, obtaining 6 different tachycardias (4 CTI dependent macro-reentry: 3 w/anticlockwise activation; 1 localized re-entry in SVA; 1 focal AT in SVA).  No arrhythmia was induced in the other 3 procedures, however, in a patient with a previous CTI ablation, evidence of a gap in the ablation line on the voltage map was found. Ablation was performed with an irrigated, contact force, 3.5 mm catheter in 6 of the 8 procedures (75%). A retrograde transaortic approach was used in 3 of CTI dependent macro-reentries (75%). In one patient (who underwent two procedures) ablation was performed through a baffle leak. We report an acute success rate of ablation of 100%, and a recurrence rate of 20% on medium-term follow up. There were no major complications; nonetheless, one patient with history of morbid obesity had a minor vascular complication on the femoral puncture site treated medically.

Conclusions

it’s feasible and safe to use this new mapping catheter in patients with history of atrial switch surgery, both via retrograde and anterograde approach on the PVA and SVA respectively. The most frequent tachycardia observed in this study was anticlockwise CTI-dependent atrial flutter.

Abstract Figure. Patient characteristics

1326Identification of arrhythmic isthmus in patients with transposition of the great arteries treated with atrial switch surgery using a new high-definition wavefront-activation-orientation grid catheter

INTRODUCTION

Patients with D- transposition of the great arteries (TGA) treated with Senning or Mustard surgeries have several atrial scars that predispose them to develop atrial tachycardias (AT). Identification of scar zones and possible arrhythmic isthmus in voltage mapping will help to guide the ablation.

AIM

To describe the feasibility of using a specific mapping catheter to identify possible arrhythmic isthmus in this set of patients.

METHODS

Prospective observational study in patients with history of SVT and atrial switch surgery, that underwent electrophysiologic study (EP) and electroanatomic (EA) mapping with a new 8Fr deflectable, multipoint wavefront-activation-orientation independent Grid catheter, in a third level hospital since April 2018 until May 2019, with medium-term follow-up.

RESULTS

A total of 8 EPs were performed in 7 patients (3 (57%) Female, median age 35 ± 6,3 y.o.). Figure 1A shows the localization and percentage of scar identified in both atria. A total of 6 AT were induced. In this, an arrhythmogenic isthmus was identified and, in all patients, at least one non-arrhytmogenic isthmus was documented. Figure 1B shows anatomical and electrophysiological characteristics of the isthmus. Arrhythmogenic isthmus had slower conduction velocity than non-arrhytmogenic ( mean 0,44m/s (IQI 0,17-0,62)  vs  1,05 m/s (IQI 0,86-1,39) p = 0.008) and fractionated potentials were detected more frequently (100% vs 50% p = 0.089)

CONCLUSION

EA mapping with a new a multipoint, high-definition, Grid Cather is feasible and allows the identification and electrophysiological characterization of arrhythmogenic and non-arrhytmogenic isthmus in patients with TGA treated with atrial switch surgery.

Abstract Figure 1

Ultra-early continuous cardiac monitoring improves atrial fibrillation detection and prognosis of patients with cryptogenic stroke

BACKGROUND AND PURPOSE

Subclinical atrial fibrillation (AF) is known to underlie a number of cases of cryptogenic stroke (CrS). However, there is need to define the most effective strategy for AF detection. The diagnostic usefulness was analysed of a strategy based on ultra-early continuous monitoring in patients with CrS in terms of AF detection, oral anticoagulation treatment and stroke recurrence, in comparison to a standard outpatient strategy.

METHODS

Patients with ischaemic stroke of undetermined origin and confirmed to be cryptogenic after extensive work-up were searched for AF with (i) a conventional strategy (historical cohort, n = 101) with serial electrocardiograms and 24-h Holter monitoring or (ii) an ultra-early monitoring strategy with insertable cardiac monitor (ICM) implanted before discharge (prospective cohort, n = 90). AF episodes lasting >1 min, anticoagulant treatment and stroke recurrence were recorded.

RESULTS

During admission, AF was similarly detected in both cohorts (24% of patients). After discharge (mean follow-up 30 ± 10 months), AF detection rates were 17/80 (21.3%) and 38/65 (58.5%) for patients in the conventional versus the ultra-early ICM group (P < 0.001). Up to 41% of AF cases in the ICM cohort were detected within the first month. Oral anticoagulation was initiated in 37.6% versus 65.5% (P < 0.001) and stroke recurrence was recorded in 10.9% versus 3.3% (P 0.04) in the conventional versus the ICM cohort.

CONCLUSIONS

Pre-discharge ICM implant allows detection of AF during follow-up in up to 58% of selected patients with CrS. Compared to a conventional strategy, ultra-early ICM implant results in higher anticoagulation rates and a decrease in stroke recurrence.

Temporal evolution of a seismic sequence induced by a gas injection in the Eastern coast of Spain

Induced seismicity associated with energy production is becoming an increasingly important issue worldwide for the hazard it poses to the exposed population and structures. We analyze one of the rare cases of induced seismicity associated with the underwater gas storage operations observed in the Castor platform, located in the Valencia gulf, east Spain, near a complex and important geological structure. In September 2013, some gas injection operations started at Castor, producing a series of seismic events around the reservoir area. The larger magnitude events (up to 4.2) took place some days after the end of the injection, with EMS intensities in coastal towns up to degree III. In this work, the seismic sequence is analyzed with the aim of detecting changes in statistical parameters describing the earthquake occurrence before and after the injection and identifying possible proxies to be used for monitoring the sequence evolution. Moreover, we explore the potential predictability of these statistical parameters which can be used to control the field operations in injection/storage fluid reservoirs. We firstly perform a retrospective approach and next a perspective analysis. We use different techniques for estimating the value of the expected maximum magnitude that can occur due to antropogenic activities in Castor.

Role of genetic testing in arrhythmogenic right ventricular cardiomyopathy/dysplasia

In a cohort of patients with confirmed or suspected arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D), genetic testing is useful in confirming the diagnosis, particularly in individuals who do not completely fulfil Task Force criteria for the disease, thereby also enabling the adoption of preventive measures in family members. Due to the high percentage of novel mutations that are expected to be identified in ARVC/D, the use of genetic screening technology based on the identification of known mutations seems to have very restricted value. Our results support that the presence of certain genetic variations could play a role in the final phenotype of patients with ARVC/D, where single and compound mutation carriers would have more symptomatic forms of the disease and the polymorphism P366L could be associated to a more benign phenotype.

Combination of clinical risk profile, early exercise testing and circulating biomarkers for evaluation of patients with acute chest pain without ST-segment deviation or troponin elevation

OBJECTIVE

To investigate the combination of clinical data, exercise testing and biomarkers for the evaluation of patients with chest pain without ST-segment deviation or troponin elevation.

DESIGN

Prospective cohort design. SETTTING: Two teaching hospitals in Spain.

PATIENTS

422 patients presenting to the emergency department were studied. Leukocyte count, C-reactive protein (CRP), pregnancy-associated plasma protein A (PAPP-A) and N-terminal pro-brain natriuretic peptide (NT-proBNP) were determined. A validated clinical risk score (number of points according to pain characteristics and risk factors) was used for clinical evaluation and early exercise testing was performed.

MAIN OUTCOME MEASURES

Adverse events (death, myocardial infarction or revascularisation) during a median 60 weeks follow-up.

RESULTS

By receiver operating characteristic curve analysis, the association between death or myocardial infarction and adverse events was not significant with leukocyte count (p = 0.3, p = 0.3) or CRP (p = 0.5, p = 0.8), was borderline significant with PAPP-A (p = 0.07, p = 0.04) and strongly significant with NT-pro-BNP (p = 0.0001, p = 0.0001). By Cox regression including clinical risk score, exercise testing result and biomarkers, exercise testing was the independent predictor of revascularisation (p = 0.0001), whereas risk score (p = 0.03) and NT-proBNP (p = 0.0004) predicted death or myocardial infarction. The inclusion of NT-proBNP improved the accuracy of the model for death or myocardial infarction (C-statistic 0.84 versus 0.76, p = 0.01). The combination of clinical score and NT-proBNP afforded the stratification in high (17.2%, p = 0.0001), intermediate (5.3%) and low (1.1%) risk categories of death or myocardial infarction.

CONCLUSIONS

NT-proBNP provides incremental prognostic information above that given by clinical history and exercise testing in patients with chest pain without ST-segment deviation and negative troponin.

Elevated levels of serum interleukin-6 are associated with low grade cellular rejection in patients with heart transplantation

Endomyocardial biopsy is the gold-standard procedure to diagnose acute cellular rejection after heart transplantation. This study assessed whether the blood levels of cytokines involved in inflammation and immune activation are useful to detect the presence of acute cellular rejection.

METHODS

Blood specimens collected before 275 endomyocardial biopsies in 66 patients were assayed for levels of TNFalpha, IL6, IL1beta, and IL2 receptor. The biopsies were grouped according to the presence (n = 41) or absence (n = 234) of acute cellular rejection grade > or = 3A of the International Society for Heart and Lung Transplantation. We compared the levels of cytokines in the two groups.

RESULTS

Circulating IL6 levels were significantly higher when there was a low grade (0-2) cellular rejection in the biopsy versus the group of biopsies grade > or = 3A (19.8 +/- 27 versus 12.9 +/- 10 pg/mL; P = .001). An IL6 level higher than 30 pg/mL showed a negative predictive value of 95% for the presence of acute rejection grade > or = 3A.

CONCLUSION

In heart transplant patients, high levels of serum IL6 were associated with low grade cellular rejection. Determination of IL6 levels may be useful to reduce the number of endomyocardial biopsies during follow-up in these patients.

Cloning and expression of two genes coding for sodium pumps in the salt-tolerant yeast Debaryomyces hansenii

Two genes encoding Na(+)-ATPases from Debaryomyces hansenii were cloned and sequenced. The genes, designated ENA1 from D. hansenii (DhENA1) and DhENA2, exhibited high homology with the corresponding genes from Schwanniomyces occidentalis. DhENA1 was expressed in the presence of high Na(+) concentrations, while the expression of DhENA2 also required high pH. A mutant of Saccharomyces cerevisiae lacking the Na(+) efflux systems and sensitive to Na(+), when transformed with DhENA1 or DhENA2, recovered Na(+) tolerance and also the ability to extrude Na(+).

Molecular cloning of the calcium and sodium ATPases in Neurospora crassa

Using PCR, reverse transcription-PCR (RT-PCR) and colony hybridization in a genomic library, we isolated six genes which encode type II P-type ATPases in Neurospora crassa. The six full-length cDNAs were cloned in a yeast expression vector and transformed into Saccharomyces cerevisiae null Ca2+- or Na+-ATPase mutants. Three cDNAs suppressed the defect of the Ca2+ mutant and two of these protected from Mn2+ toxicity. One cDNA suppressed the defect of the Na+ mutant and two cDNAs were not functional in S. cerevisiae. The expression of the transcripts of the six genes in the presence of Ca2+, Na+, high pH or supporting an osmotic shock indicated that, with the exception of one of the Ca2+-ATPases, the main function of the cloned ATPases is the adaptation to stress conditions. The relationship between the cloned fungal Ca2+- and Na+-ATPases and plant type II P-ATPases is discussed.

Norepinephrine, tri-iodothyronine and insulin upregulate glyceraldehyde-3-phosphate dehydrogenase mRNA during Brown adipocyte differentiation

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene expression was studied in differentiating brown adipocytes. Northern blot analysis showed that GAPDH mRNA levels increased during differentiation of precursor cells into mature adipocytes, mainly in the initial stages of the differentiation process. Insulin, tri-iodothyronine (T(3)) and norepinephrine, the main regulators of brown adipose tissue function, upregulated GAPDH mRNA levels, whereas retinoic acid inhibited them. The effect of insulin was present on all culture days examined, was time- and dose-dependent, and was exerted through its own receptors, as demonstrated by comparing insulin and insulin-like growth factor (IGF)-I and -II potencies in this system. Using the transcriptional inhibitor, actinomycin D, we demonstrated that T(3), and to a lesser extent insulin, stabilized GAPDH mRNA. Experiments with cycloheximide indicated that both hormones require de novo protein synthesis to achieve their effects. Using cAMP analogs, we showed that the effect of norepinephrine is probably exerted through this second messenger. Co-operation was elucidated between norepinephrine- and insulin-mediated induction of GAPDH mRNA levels. In summary, we have demonstrated that GAPDH mRNA is subjected to multifactorial regulation in differentiating brown adipocytes that includes differentiation of precursor cells and the lipogenic/lipolytic regulators of the tissue.

Overexpression of the sodium ATPase of Saccharomyces cerevisiae: conditions for phosphorylation from ATP and Pi

The ENA1 gene of Saccharomyces cerevisiae encodes a putative ATPase necessary for Na+ efflux. Plasma membranes and intracellular membranes of a yeast strain overexpressing the ENA1 gene contain significant amounts of ENA1 protein. Consequences of the overexpression with reference to the wild-type strain are: (1) a 5-fold higher content of the ENA1-protein in plasma membranes; (2) lower Na+ and Li+ effluxes; (3) slightly higher Na+ tolerance; and (4) much higher Li+ tolerance. The ENA1-specific ATPase activity in plasma membrane preparations of the overexpressing strain was low, but an ENA1 phosphoprotein was clearly detected when the plasma membranes were exposed to ATP in the presence of Na+ or to Pi in the absence of Na+. The characteristics of this phosphoprotein, which correspond to the acyl phosphate intermediaries of P-type ATPases, the absolute requirement of Na+ or other alkali cations for phosphorylation, and the Na+ and pH dependence of phosphorylation from ATP and Pi suggest that the product of the ENA1 gene may be a Na,H-ATPase, which can also pump other alkali cations. The role of the intracellular membranes structures produced with the overexpression of ENA1 in Na+ and Li+ tolerances and the existence of a beta-subunit of the ENA1 ATPase are discussed.

Effects of cyclosporine A on the rat liver and kidney protein pattern, and the influence of vitamin E and C coadministration

The effects of cyclosporine A (CsA), a potent immunosuppressive drug, were examined in rat liver and kidney samples using two-dimensional electrophoretic protein analysis. Of a total of 370 liver and 336 kidney spots analyzed, 8% (29 spots) and 6% (19 spots), respectively, showed a significant drug-induced change (p < 0.01), which was predominantly reflected in increased protein abundance (62% and 74% of the changes, respectively). Of the 48 proteins changed in either organ, 14 were most probably common to both tissues and one of these was significantly increased in both the liver and the kidney. Most of the other 13 showed similar trends (either increases or decreases) in both organs. However, the most striking drug effect seen in this study concerned an unidentified protein present only in the kidney, which completely disappeared upon CsA treatment. It was also investigated whether the drug-induced changes could be prevented by the coadministration of the radical scavengers vitamin E and C with CsA. Spots changed by the administration of the drug were classified according to three different categories, based on their response profiles in rats treated with CsA in combination with the vitamins: (i) spots which were changed by CsA as well as by CsA in combination with the vitamins (12 liver and 4 kidney spots), (ii) spots which were changed by CsA and showed an additional increase of this change by CsA plus the vitamins (no liver and 4 kidney spots), and (iii) spots which were changed by CsA but not by CsA in combination with the vitamins (8 liver and 6 kidney spots). These results showed that in both organs the vitamins were able to prevent around 30% of the effects caused by CsA, and that two-dimensional gel electrophoresis is an excellent tool to demonstrate such drug interactions at the molecular level.

Insulin regulation of malic enzyme gene expression in rat liver: evidence for nuclear proteins that bind to two putative insulin response elements

Diabetes in rats is characterized by insulin deficiency accompanied by a decrease in lipogenic enzymes. The malic enzyme (ME) gene, which encodes an important lipogenic enzyme, was used to investigate insulin regulation of gene expression. ME mRNA levels were reduced by more than 90% in the liver of diabetic rats. The administration of insulin (3 U/15 days) to either control or diabetic rats increased ME mRNA by 2- to 10-fold, respectively. Since diabetes reduces circulating T3 and the levels of nuclear T3-receptors, the potential role of thyroid hormone on insulin regulation of ME gene expression was also evaluated in thyroidectomized-diabetic rats. In these animals the levels of ME mRNA were undetectable but were increased by insulin even in the absence of thyroid hormones. These in vivo effects of insulin and T3 were not additive. The transcription rate of the gene was also reduced in the diabetic liver and recovered after insulin therapy. By computer analyses we have identified two different putative insulin response elements (IREs) in the ME gene promoter, hereafter referred to as IRE-I (-683 to -692), which is similar to the phosphoenol pyruvate carboxy kinase promoter IRE and IRE-II (-161 to -170), which is similar to the glyceraldehyde phosphate dehydrogenase gene promoter IRE-A. Results from gel retardation assays suggest that a single nuclear protein binds to IRE-I whereas two different nuclear proteins bind to IRE-II. The protein/IRE-I complex increased in liver nuclear extracts from diabetic rats and decreased after insulin administration.(ABSTRACT TRUNCATED AT 250 WORDS)

The low-affinity component of Saccharomyces cerevisiae maltose transport is an artifact

It has been reported by several laboratories that maltose transport in Saccharomyces cerevisiae consists of two components with high- and low-affinity constants for maltose. We have investigated the characteristics of the low-affinity component and have found that it shows an abnormal behavior without similarity to any transport mechanism described in this organism. The results strongly indicate that this apparent transport activity is due not to a genuine transport process but to nonspecific binding of maltose to the cell wall and plasma membrane.

In vivo activation of the yeast plasma membrane ATPase during nitrogen starvation. Identification of the regulatory domain that controls activation

Yeast plasma membrane ATPase is activated during nitrogen starvation when a fermentable substrate is present. This activation is due to changes in the Vmax and it is irreversible, independent of protein synthesis and apparently triggered by a decrease in the intracellular pH. It is shown that the ATPase regulatory domain implicated in the activation by fermentable carbon sources is also implicated in activation by nitrogen starvation and by external acidification.

Turnover of the K+ transport system in Saccharomyces cerevisiae

The stability of the K+ transport system in Saccharomyces cerevisiae has been studied upon inhibition of protein synthesis with cycloheximide. Addition of the antibiotic gave rise to an inactivation of this transport. This activation followed first-order kinetics and was stimulated by the presence of a fermentable substrate. A half-life of about 4 h could be calculated in the presence of glucose. The results indicate that, similarly to sugar carriers, K+ transport system is less stable than the bulk of proteins of this organism.

Half-life of the plasma membrane ATPase and its activating system in resting yeast cells

The stability of the yeast plasma membrane ATPase and its activating system has been investigated in resting Saccharomyces cerevisiae. The half-life of ATPase in the presence of glucose is about 11 h whereas in the presence of ethanol it is greater than 30 h. In the case of the ATPase activating system half-life values of about 5 and 14 h have been observed, respectively, in the presence of these substrates. These results indicate that, similarly to sugar transport systems, plasma membrane ATPase as well as its activating system are less stable than the bulk of proteins in this organism. The fact that all plasma membrane proteins so far examined show low half-life values suggests that a low stability could be a general characteristic of these proteins.

Inhibition of biosynthesis of Saccharomyces cerevisiae sugar transport system by tunicamycin

Tunicamycin apparently inhibited the biosynthesis of glucose, galactose, and maltose transport systems in Saccharomyces cerevisiae. Under the conditions used, the antibiotic also blocked the biosynthesis of invertase, a well-known yeast glycoprotein, as well as the glycosylation of a marker mannoprotein of the yeast cell wall. However, the antibiotic did not affect certain proteins which did not contain carbohydrate. It seems, therefore, that these sugar carriers are glycoproteins.