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Biomedical subjects

D Lacroix

Publications and source records attributed to D Lacroix.

At least 73 records · Page 4Linked to original sources
PubMed1996

[Prognostic factors after sustained ventricular fibrillation or tachycardia. A multivariate study apropos of 160 cases].

The authors analysed survival of 160 patients (121 men and 31 women; average age 57.2 +/- 12.5 years; follow-up 29 +/- 20 months) treated for malignant ventricular arrhythmias (sustained ventricular tachycardia, ventricular fibrillation, syncope with inducible ventricular tachycardia). The therapeutic evaluation was frequently invasive (145 patients underwent at least programmed ventricular stimulation, 108 patients underwent full endocavitary electrophysiological studies) and non-pharmacological therapy was widely used (defibrillator n = 44; antiarrhythmic surgery n = 28; ablative procedures n = 19; transplantation n = 7). The following underlying pathologies were observed: ischaemic heart disease n = 120; non-ischaemic left heart disease n = 19; right heart cardiac disease n = 4; and apparently normal hearts n = 17). The average ejection fraction was 40.5 +/- 15.5% and 29 patients were in the NYHA functional classes III or IV. Fifty-five patients had life-threatening arrhythmias whilst receiving amiodarone. At 2 years, the actuarial sudden death rate was 5.9 +/- 2.1% and the actuarial total cardiac mortality rate was 13.1 +/- 2.9%. Univariate analysis showed age, the presence of underlying cardiac disease, the presence of dilated cardiomyopathy, the absence of an invasive approach, the need for basal pacing in electrical cardioversion, the absence of betablocker therapy, a decreased left ventricular ejection fraction and a high NYHA functional class, to be predictive of sudden death. In multivariate analysis, age, the NYHA class for total cardiac mortality and the NYHA class for sudden death, were the only independent predictive factors. The authors conclude that in the era of invasive methods of evaluation and widespread use of non-pharmacological therapeutic methods, the symptomatology of cardiac failure assessed by the NYHA classification remains the most powerful independent prognostic factor after an episode of malignant ventricular arrhythmia.

Actuarial Analysis↗
PubMed1996

[Anxiety disorders and unexplained syncopes of presumed vaso-vagal origin].

The impact of anxiety neurosis on the diagnosis and treatment of patients with unexplained syncope (S) was assessed in 178 patients (91 women and 87 men) with an average age of 36.5 +/- 20 years, presenting with 10.7 +/- 24 episodes of S). None had evidence of underlying cardiac disease apart from 7 patients with mild hypertension. All patients underwent a tilt test (TT) at 60 degrees for 45 minutes. A bolus of isoproterenol was injected intravenously in subjects with negative TT. After the test, the patients were classified according to the presence (n = 38) or absence (n = 140) of anxiety neurosis based on the DSM III-R diagnostic. The TT was positive in 76 patients, 9 of whom had a cardioinhibitory reaction with prolonged asystole. Patients with anxiety had more episodes of S (24 +/- 43 versus 7 +/- 13; p = 0.001), a shorter interval between S (11.5 +/- 23 months versus 12.5 +/- 20 months, p = 0.02) but more negative TT (27/38 versus 75/140; p = 0.05). One hundred and sixty-eight patients were followed up : 10 were lost to follow-up. Preventive treatment was undertaken in 59 patients who were representative of the whole group with respect to age (30 +/- 18 years 39 +/- 21 years : p = 0.004). After an average follow-up of 24.5 +/- 15 months, 26 patients (15%) experienced a recurrence of S. The recurrence rate was identical in patients with positive and negative TT and in treated and untreated cases. On the other hand, recurrence was higher in those with anxiety (12/25 versus 14/117; p = 0.001) who also had less improvement of symptoms (12/15 versus 74/120; p = 0.001). The "anxiety" variable was therefore identified as being the only predictive factor for recurrence of syncope. The authors conclude that in patients referred for investigation of unexplained syncope, some suffer from anxiety neurosis, in whom the TT is usually negative, and have a higher risk of recurrence. They justify a specific therapeutic management.

Adolescent↗
PubMed1995

Quantified EEG changes associated with a positive clinical response to clozapine in schizophrenia.

1. The authors conducted a retrospective exploratory computerized EEG study on the effect of clozapine in treatment-refractory schizophrenics, 10 high-responders (HRs) and 10 low-responders (LRs), in an attempt to correlate amplitude but especially coherence changes with a positive clinical response to clozapine. 2. EEGs with eyes closed were obtained before and during a clozapine treatment. Both groups had a similar drug profile with regards to non-clozapine medication. Probability maps were computed to illustrate changes of amplitude and coherence (for all combinations of paired electrodes) for 4 frequency bands (theta, alpha, beta 1 and 2). 3. The effect on AMPLITUDE was a generalized increase in lower bands and a decrease in anterior regions in higher bands of both HRs and LRs. Considerable changes of COHERENCE were observed on a wide set of paired electrodes in most frequency bands with some electrodes involved in HRs but uninvolved or differently involved in LRs suggesting differences in selected brain regions. 4. Changes of coherence but not amplitude were correlated with changes on the BPRS, thus to clinical improvement, and concerned mostly the right anterior-medial temporal (T4) and central (C4) electrodes paired with prefrontal electrodes, left central (C3), temporal (T3) and parietal (P3) electrodes in the theta band. 5. Clozapine has both generalized and regional effects as can be suspected considering its effect on many subtypes of brain receptors. A brain dysfunction centralized on the right anterior-medial temporal region may characterize treatment-refractory schizophrenics.

Adult↗
PubMed1995

Synthesis of a selenomethionine peptide and a preliminary study of transport into Escherichia coli monitored by high-performance liquid chromatography.

The tripeptide Gly-SeMet-Gly has been synthesized by a combination of solution and solid-phase methods. Increase in weight of the resin was very nearly theoretical, and purification was straightforward. Its absorption was compared to that of the corresponding peptide, Gly-Met-Gly, in E. coli using HPLC ion-exchange separation and fluorometric determination of the disappearance of peptides in the culture medium and the appearance of methionine and selenomethionine in the same culture medium. As E. coli are not known to possess extracellular peptidases, and in fact have been shown to possess transport systems for peptides, this absorption is interpreted as transport of the peptide through the cell wall and membrane into the cytoplasm, endohydrolysis of the peptide, and efflux of the peptides' amino acids. Uptake of both peptides was approximately equal, but was slowed when both peptides were present simultaneously.

Amino Acid Sequence↗
PubMed1995

Determination of left ventricular mass in systemic hypertension: comparison of standard and signal averaged electrocardiography.

OBJECTIVE: To investigate the quantitative relationship, if any, between signal averaged electrocardiographic variables and echocardiographically determined left ventricular mass in hypertensive subjects. DESIGN: Cohort analytic prospective study. SETTING: University hospital. SUBJECTS: 50 hypertensive subjects selected consecutively from inpatients. Patients older than 75 years, with underlying cardiac disease, with inconclusive echocardiograms with bundle branch block, or in atrial fibrillation were excluded. INTERVENTIONS: Antihypertensive therapy involving 41 patients was continued. MAIN OUTCOME MEASURES: Left ventricular mass calculated in accordance with the standards of the Penn convention. Thirteen criteria derived from combinations of signal averaged electrocardiographic X, Y, and Z Frank orthogonal leads, including voltage criteria, duration, and time-voltage integrals of the QRS complex. Four widely used standard electrocardiographic criteria for detection of left ventricular hypertrophy. RESULTS: There was no difference in the values for any of the electrocardiographic variables between patients with (n = 29) and without left ventricular hypertrophy (n = 21). The time-voltage integral of QRS in the horizontal plane was the best signal averaged variable related to left ventricular mass (r = 0.33, P = 0.019); however, the correlation with Rodstein voltage was stronger (r = 0.46, P = 0.0009). A positive correlation was also found between left ventricular indexed mass and Rodstein voltage (r = 0.43, P = 0.0019). Stepwise regression analysis revealed Rodstein voltage as the only predictor of indexed mass (P = 0.0019), and Rodstein voltage (P = 0.0022) and body weight (P = 0.011) as the only independent correlates of left ventricular mass. CONCLUSIONS: The relation between electrocardiographic variables and left ventricular mass or indexed mass is of limited value; signal averaged orthogonal leads do not improve this assessment compared with standard electrocardiographic leads.

Electrocardiography↗
PubMed1995

[Automatic implantable defibrillators. Clinical experience apropos of 45 patients].

The aim of this study was to analyse the efficacy and survival after implantation of an automatic cardioverter-defibrillator.. Forty-five patients including 37 men were followed up for 0 to 51 months. The indications were ventricular fibrillation with no curable cause (n = 27) and sustained resistant or poorly tolerated ventricular tachycardia (n = 17) when programmed ventricular pacing with antiarrhythmic therapy was not applicable or gave poor results. One patient was implanted with this device for torsades de pointes. The underlying cardiac disease was ischaemic in 34 cases, non-ischaemic in 8 cases, and 3 patients had no apparent cardiac disease. Twenty patients were implanted with an epicardial system (group I) and 25 patients with endocardial system (group II). In group II, there was one complete failure of implantation requiring the use of an epicardial system and 2 partial failures requiring an additional epicardial patch electrode. The perioperative mortality was 2/45 (4.4%), both cases being due to permanent arrhythmias. In 5 patients, the minimal effective energy of defibrillation was over 25 Joules at implantation, without any untoward consequences on the clinical outcome. Ten non-fatal complications were observed including two major problems (haemopericardium); there were two cases of late increase of the minimal effective energy of defibrillation requiring the addition of a subcutaneous patch. Twenty-four patient (53%) received at least one appropriate therapy; 14 patients (36%) had at least one inappropriate shock during follow-up. During follow-up, 7 patients died, 6 of a cardiac cause and 3 of an arrhythmic problem.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

[Automatic implantable defibrillator and antiarrhythmic surgery in ischemic cardiopathies. Apropos of 53 cases].

The automatic implantable defibrillator (AID) and antiarrhythmic surgery are the two therapeutic options after failure of catheter ablation and/or antiarrhythmic therapy for sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) in patients with coronary artery disease. The authors undertook retrospective study of the characteristics of two groups of patients treated between November 31st 1987 et December 31st 1993 either by AID (28 men and 4 women with an average age of: 56.1 +/- 11.2 years) or by surgery (19 men and 2 women with an average age of: 60.6 +/- 6.8 years). The "surgical" patients differed from "defibrillator" patients in the fewer number of cardiac arrests, a higher proportion of sustained monomorphic VT, better tolerated sustained monomorphic VT (rarely syncopal), fewer early post-infarction arrythmias (< or = 8 weeks), more anterior wall infarction and a higher proportion of aneuvrysms. The perioperative mortality was 6.2% in the "defibrillator" group and nil in the "surgical" group (p = NS). At 2 years, the sudden death rate in the "defibrillator" and "surgical" groups was 7.5% and 0% respectively and total cardiac mortality was 17% and 20% respectively (p = NS). The authors conclude that perioperative mortality and the sudden death rate at 2 years are relatively low in the two groups. However, the total cardiac mortality remains high, largely related to perioperative death and secondary cardiac failure. Nevertheless, compared with defibrillator patients and with identical average ejection fractions, there was no extra mortality due to cardiac failure after antiarrhythmic surgery.

Aged↗
PubMed1994

Brain activation with a maze test: an EEG coherence analysis study in healthy subjects.

The maze test is a complex cognitive task involving visuoperceptual, planning and foresight abilities. EEGs were recorded from 20 healthy subjects according to the 10/20 system. Coherence is analogous to a correlation coefficient between the signals recorded by two electrodes and is computed between each electrode paired to all other electrodes. The maze test provoked changes of coherence mainly within the prefrontal regions, between parietal and central electrodes paired with frontal electrodes, especially the right frontopolar and the left prefrontal electrodes, and in the posterior temporal, parietal and occipital regions. EEG coherence analysis detects changes in regions known to be involved in visual processing and executive functions.

Adult↗
PubMed1994

Vasospastic angina without flow-limiting coronary lesions as a cause for aborted sudden death.

Two patients resuscitated from out-of-hospital cardiac arrest were later found to have minor coronary atherosclerosis and no inducible ventricular arrhythmia. Coronary spasm was not elicited during provocative tests but occurred on introduction of the catheter in the right coronary artery and spontaneously recurred after resuscitation, leading to myocardial infarction in one patient. Both patients received an implantable cardioverter defibrillator and subsequent discharges, while receiving calcium antagonists.

Adult↗
PubMed1994

Optimization of an Escherichia coli formate dehydrogenase assay for selenium compounds.

A microbiological assay to detect different chemical compounds of selenium for potential future use in the study of the distribution of these chemical forms in foods is being developed. This assay is based on the detection, by infrared analysis, of CO2 in a culture of Escherichia coli when the bacteria are grown in the presence of various selenium compounds. The CO2 production is the result of selenium-dependent formate dehydrogenase activity, which catalyzes oxidation of formic acid produced during glucose metabolism. Smooth response curves were generated over several orders of magnitude for selenocystine, selenite, and selenomethionine. The assay detects selenium concentrations (above background) as low as 1.5 nM for selenocystine and selenite and 4 nM for selenomethionine in minimal medium. Detection of selenomethionine was enhanced (to a sensitivity of 1.5 nM) by the addition of methionine to minimal medium and was enhanced even further (to a sensitivity of 0.8 nM) by the addition of a defined mixture of amino acids. Selenomethionine could be assayed in the presence of an amino acid concentration which is proportional to the amino acid/elemental selenium ratio found in a wheat gluten reference material (NIST SRM 8418). This implies that the assay can detect selenium compounds in a variety of foods at low concentrations, avoiding the background CO2 production caused by high concentrations of non-selenium-containing amino acids. The observation that methionine enhanced selenomethionine availability for formate dehydrogenase synthesis supports studies in animals demonstrating that methionine controls selenomethionine incorporation into selenoenzymes.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1994

[Thromboembolic complications of arrhythmia due to atrial fibrillation].

Fifteen per cent of cerebrovascular accidents have a cardiac origin, two thirds of which are due to atrial fibrillation (AF). The Framingham study showed the risk of an ischaemic cerebral event to be increased by 5.6 in AF unrelated to rheumatic heart disease and by 17.5 when AF is associated with valvular heart disease. The risk of embolism is higher in elderly subjects and in those with underlying cardiac disease. Other high risk conditions include hypertension, diabetes, hyperthyroidism and cases with echocardiographic changes: left atrial dilatation, pre-thrombotic state or intra-atrial thrombus, atheroma of the ascending aorta. This stratification of risk should be taken into account when deciding on treatment. Conscious of the importance of the risk of embolism in AF, several authors have undertaken, over the last few years, randomised studies of the prevention of thromboembolic complications of AF: the AFASAK, BAATAF, SPAF and SPINAF trials. All showed the unquestionable efficacy of warfarin, even at low doses, at the price of a haemorrhagic risk of less than 2% per year for severe haemorrhages. A more recent study (SPAF II) confirmed the value of aspirin at the dosage of 325 mg/day which would seem to be a good alternative to anticoagulant therapy when this is contraindicated, although aspirin is less effective. The indications for anticoagulant therapy have become clearer since the publication of these results. Anticoagulant therapy is essential in permanent AF whether or not associated with rheumatic heart disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Influence of clinical and hemodynamic characteristics on signal-averaged electrocardiogram in postoperative tetralogy of Fallot.

This study examines the relation between signal-averaged electrocardiographic measurements and the occurrence of spontaneous ventricular arrhythmias in 86 patients with a postoperative right bundle branch block after repair of tetralogy of Fallot; special attention was given to the influence of age, body surface area and right ventricular systolic pressure on signal-averaged electrocardiograms. Twenty-eight of the 86 patients had significant ventricular arrhythmias on 24-hour ambulatory monitoring. A positive linear correlation was found between filtered QRS duration and age at evaluation or body surface area (r = 0.45, p = 0.00001; r = 0.54, p < 0.00001, respectively) and between amplitude of the last 40 ms of the filtered QRS and right ventricular systolic pressure (r = 0.48, p < 0.001). A negative linear correlation was found between amplitude of the last 40 ms of the filtered QRS and age at evaluation or body surface area (r = -0.27, p = 0.01; r = -0.34, p = 0.002, respectively). When the age of the patients or the body surface area was considered with an analysis of covariance, the presence of ventricular arrhythmias was associated with a higher amplitude of the last 40 ms of the filtered QRS. In addition, an amplitude of the last 40 ms of the filtered QRS > 170 microV had an excellent sensitivity (100%) and a good specificity (88%) for identifying patients with both right ventricular systolic hypertension and spontaneous ventricular arrhythmia. Thus, adjustment of signal-averaged parameters for age at evaluation and body size is mandatory when studying postoperative tetralogy of Fallot.

Adolescent↗
PubMed1993

Acute electrophysiological effects of intravenous milnacipran, a new antidepressant agent.

Milnacipran is a new antidepressant agent selected from a series of cycloproprane derivatives. The aim of this study was to investigate the acute electrophysiological effects and the tolerance of intravenous administration of this drug in 10 patients without any abnormality as shown in an electrophysiological study done for various complaints. Milnacipran was given over a 30-min period at doses of 0.2 mg/kg (2 patients), 0.4 mg/kg (2 patients) and 0.8 mg/kg (6 patients). The most significant alterations observed in this study were increases in heart rate (average of maximal increase: +19.5% at 50 min, P = 0.06) and systolic blood pressure (average of maximal increase: +21.5% at 10 min, P < 0.005), and decreases in the functional refractory period of the atrium (-3%, P < 0.05), the atrioventricular node (-9%, P < 0.005) and the effective refractory period of the right ventricle (-10.8%, P < 0.05) at 50 min. The sinus node function was improved in nine patients but depressed in one patient with previous slight baseline sinus node alterations. Milnacipran being devoid of both anticholinergic and monoamine oxidase inhibition activities, these alterations could be related to inhibition of noradrenaline uptake leading to an increase of adrenergic activities. No other ECG or electrophysiological parameters were significantly altered. Five of the 10 patients reported transient nausea, four of them for the highest dosage (0.8 mg/kg) and at the moment of peak of milnacipran plasma level. In conclusion, electrophysiological effects of intravenous milnacipran are negligible. These findings differ from those, well described in the literature, for imipramine-like antidepressant agents.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Metabolism of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in human kidney epithelial cells transfected with rat CYP2B1 cDNA.

In all species where it has been tested, the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) has been shown to be a potent carcinogen, and NNK and other nitrosamines may play a role in human tobacco-related carcinogenesis. Purified rat CYP2B1 has been shown to metabolize NNK, and the CYP2B1 gene is expressed constitutively in rat lung. The objectives of this study were to test the capacity of CYP2B1, synthesized from a rat hepatic cDNA in Ad293 cells, to metabolize NNK, and to define the type and the proportions of the final metabolites produced. Ad293 cells were transfected with a CYP2B1 expression vector (pMT2-2B1), or with a control vector and incubated in culture medium containing [3H]NNK, after which alpha-carbon hydroxylation and pyridine N-oxidation metabolites were identified by HPLC analysis and quantitated by scintillation counting. pMT2-2B1-transfected cells were capable of catalyzing alpha-carbon hydroxylation and pyridine N-oxidation of NNK, although the reduction product 4-(methylnitrosamino)-1-(3-pyridyl)-1-butan-1-ol(NNAL) was the major metabolite formed in cells regardless of transfection treatment. The total amount of alpha-carbon hydroxylation metabolites produced by pMT2-2B1-transfected cells was greater than that of pyridine N-oxidation metabolites. However, pMT2-2B1 transfected cells produced approximately ten-fold more pyridine N-oxidation metabolites and only two-fold more alpha-carbon hydroxylation metabolites than control cells. Furthermore, the amount of NNAL-N-oxide was much lower than that of NNK-N-oxide in the medium of pMT2-2B1-transfected cells, even though the amount of available NNAL, resulting from carbonyl reduction of NNK, was very high; this suggests that NNAL is poorly N-oxidized by CYP2B1 compared to NNK. These results show that within living cells NNK was metabolized by CYP2B1 via both the pyridine N-oxidation and alpha-carbon hydroxylation pathways. However, CYP2B1 preferentially catalyzed pyridine N-oxidation, which is considered to be a deactivation reaction.

Animals↗