Bacterial triterpenoids of the hopane series from the prochlorophyte Prochlorothrix hollandica and their intracellular localization.

35-O-beta-Galacturonopyranosyl-, 35-O-beta-3,5-anhydro-galacturonopyranosyl- and 35-O-alpha-altruronopyranosylbacteriohopanetetrol accompanied by their 2 beta-methyl homologues have been isolated from Prochlorothrix hollandica. We report here C35 triterpenoids of the hopane series in a prochlorophyte, a group of prokaryotic oxigenic phototrophs of the cyanobacterial lineage. Like many cyanobacteria, P. hollandica contains a mixture of non-methylated as well as 2 beta-methylhopanoids. After side-chain cleavage by periodic acid oxidation followed by sodium borohydride reduction, these hopanoids could be localized in cell walls and thylakoids, in accordance with their role as membrane stabilizers.

Structure elucidation and biosynthesis of 31-methylhopanoids from Acetobacter europaeus. Studies on a new series of bacterial triterpenoids.

Apart from a mixture of bacteriohopanetetrols already found in other Acetobacter species, four new 3 beta-methylhopanoids have been isolated from Acetobacter europaeus. All of them present an ether linkage between a bacteriohopanetetrol or a bacteriohopanepentol and a carbapseudopentose moiety often found in bacterial hopanoids. Three of these ethers were shown by comparison with synthetic reference hopanoids to posess a supplementary methyl group at C31. This novel series of methylhopanoids may be the precursor of yet unidentified molecular fossils found in sediments. [methyl-2H3]Methionine was efficiently incorporated into the 31-methylhopanoids with retention of all three deuterium atoms in the transferred methyl group. This labelling pattern might be consistent with a rather rarely found methylation reaction of an enol.

Isoprenoid biosynthesis in bacteria: a novel pathway for the early steps leading to isopentenyl diphosphate.

Incorporation of 13C-labelled glucose, acetate, pyruvate or erythrose allowed the determination of the origin of the carbon atoms of triterpenoids of the hopane series and/or of the ubiquinones from several bacteria (Zymomonas mobilis, Methylobacterium fujisawaense, Escherichia coli and Alicyclobacillus acidoterrestris) confirmed our earlier results obtained by incorporation of 13C-labelled acetate into the hopanoids of other bacteria and led to the identification of a novel biosynthetic route for the early steps of isoprenoid biosynthesis. The C5 framework of isoprenic units results most probably (i) from the condensation of a C2 unit derived from pyruvate decarboxylation (e.g. thiamine-activated acetaldehyde) on the C-2 carbonyl group of a triose phosphate derivative issued probably from dihydroxyacetone phosphate and not from pyruvate and (ii) from a transposition step. Although this hypothetical biosynthetic pathway resembles that of L-valine biosynthesis, this amino acid or its C5 precursors could be excluded as intermediates in the formation of isoprenic units.

Localization and distribution of hopanoids in membrane systems of the cyanobacterium Synechocystis PCC 6714.

Intracellular localization of triterpenic membrane stabilizers of the hopane series is described for the first time for a cyanobacterium. In Synechocystis PCC 6714, a bacteriohopanetetrol derivative (main compound) and diplopterol were detected in cell wall (CW) and thylakoid membrane (TM). Both hopanoids were enriched 4.5-fold and 9.0-fold in CW and outer membrane (OM) fractions, respectively, compared to TMs.

Beat-to-beat detection of ventricular late potentials with high-resolution electrocardiography.

To detect dynamic changes of VLPs we developed a low-noise, HR-ECG with a gain of 10(5)-10(6)X. This system allows the beat-to-beat detection of low-amplitude signals at the bedside in a nonshielded room without any averaging process. Analysis was performed in 39 normal subjects (group A: 27 men, 12 women, mean age, 28 +/- 8 years), in 98 patients with coronary artery disease without documented sustained ventricular tachycardia (group B: 86 men, 12 women, mean age, 59 +/- 10 years) and in 41 patients coronary artery disease with sustained monomorphic ventricular tachycardia (group C: 36 men, 5 women; mean age 63 +/- 9 years). Comparison was made with time-domain signal-averaging (SA-ECG) in all cases at the same electrode position and with identical band-pass filtering. In group A no VLPs were detected; the total filtered QRS duration was 84 +/- 8 msec (mean +/- SD), and the time interval during which the terminal QRS did not exceed 40 microV (I-40) was less than 30 msec in all cases (mean, 17 +/- 6 msec). In group B, VLPs were detected by HR-ECG in 34 of 98 patients (35%); the total QRS duration was 102 +/- 16 msec (mean +/- SD, p less than 0.01 vs group A), and the I-40 was 29 +/- 13 msec (mean +/- SD, p less than 0.01 vs (group A). In group C, VLPs were detected by HR-ECG in 38 of 41 patients (93%); the total QRS duration was 123 +/- 22 msec (mean +/- SD, p less than 0.01 vs group A and group B), and the I-40 was 40 +/- 14 msec (mean +/- SD, p less than 0.01 vs group A and group B). Concordant results between HR-ECG and SA-ECG were observed in 91% of the cases (59 positive and 103 negative results). Late potentials that exhibited dynamic variations were detected by HR-ECG alone in 13 cases, and very low amplitude VLPs were detected by SA-ECG alone in three cases. In conclusion, the present study demonstrates the feasibility of body-surface recording of VLPs on a beat-to-beat basis, without any averaging process, at the bedside in a nonshielded room. This new approach may allow the study of dynamic changes of VLPs during spontaneous ventricular arrhythmias or ischemia.

Prognostic significance of ventricular late potentials in coronary artery disease.

By means of high-gain ECG and signal-averaging techniques, we tried to determine the prevalence and prognostic significance of ventricular late potentials (VLPs) in coronary artery disease (CAD). No VLPs were detected in normal subjects (n = 25) or in patients with various noncoronary cardiopathies with sustained ventricular tachycardia and/or fibrillation (VT/VF) (n = 10). Among 92 CAD patients, VLPs were apparent in 35% (32 of 92) at the beginning of the study. The prevalence of VLPs increased to 48% (19 of 40) in the presence of ventricular aneurysm (VA) and to 82% (14 of 17) in the presence of a history of previous sustained VT/VF. To determine the prognostic significance of VLPs, a prospective analysis was conducted during a mean of 7.4 months (range 1 to 22 months). During the follow-up period, 11 patients (12%) presented with an episode of sustained VT/VF, and six of them died from documented VT/VF. Three other patients died from cardiogenic shock. An episode of sustained VT/VF occurred in 31% (10 of 32) of the patients with VLPs vs 2% (1 of 58) of the patients without VLPs (p less than 0.001), and six patients with VLPs died from sustained VT/VF vs none in the group of patients without VLPs (p less than 0.01). This VLP-related increase in arrhythmic risk was still present in the particular subgroup of patients with a history of previous sustained VT/VF (n = 17) and in patients with VA (n = 40). The risk of developing sustained VT/VF was also influenced by the length of the VLP and by a low mean ejection fraction.(ABSTRACT TRUNCATED AT 250 WORDS)

[Late potentials: non-invasive detection in coronary disease and relation to severe ventricular arrhythmia]. / Potentiels tardifs: détection non-invasive dans la maladie coronarienne et relation avec les arythmies ventriculaires graves.

Using high-gain amplification and signal averaging techniques, we tried to determine the clinical significance of ventricular late potentials (LP). 85 subjects were included in this study. No LP were detected in normal subjects (n = 25), nor in patients with various non-coronary cardiopathies who had presented ventricular tachycardia and/or fibrillation (VT/VF) (n = 10). LP were recorded only in patients with coronary heart disease (CHD) (n = 50). The prevalence of LP was 50% (9/18) in patients with a history of VT/VF (vs 12.5% = 4/32 in patients without such a history, p less than 0.02). We also found a prevalence of 50% (11/22) in patients with a ventricular aneurysm (vs 7.1% = 2/28 in patients without an aneurysm, p less than 0.01). The prevalence reached 80% (8/10) in patients with VT/VF and a ventricular aneurysm and it was only in this latter group of patients that the interval between the peak of the R wave and the end of ventricular electrical activity exceeded 100 ms (mean 111.2 +/- 12 ms, vs 50 +/- 8 ms in normal subjects, p less than 0.001). In all the cases submitted to surgery, the LP disappeared after resection of the aneurysm. In conclusion, LP, when of long duration, should be considered as a hallmark of malignant ventricular arrhythmias in patients with CHD.

[Prognostic value of the late potentials of ventricular activation in coronary disease]. / Valeur pronostique des potentiels tardifs de l'activation ventriculaire dans la maladie coronarienne.

Identification of subsets of patients with coronary artery disease (CAD) who are prone to ventricular tachycardia or fibrillation (VT/VF) and to sudden arrhythmic death still represents one of the major problems in clinical cardiology today. Ninety-two patients with CAD were included in this prospective study, which was designed to assess the prognostic significance of ventricular late potentials (VLP) detected non-invasively using high-gain electrocardiography and signal averaging. The results clearly demonstrate that the presence of VLP increases the risk of VT/VF and the risk of sudden arrhythmic death in CAD patients. Because of its high sensitivity and non-invasiveness, high-gain electrocardiography should be included among the various electrophysiological investigations used to assess prognosis in CAD patients.

[Non-invasive detection of late potentials of ventricular activation: identification and significance in coronary disease]. / Détection non invasive des potentiels tardifs de l'activation ventriculaire: identification et signification dans la maladie coronarienne.

Using a high-amplification electrocardiograph with signal averaging, an attempt has been made to determine the prevalence of delayed potentials of ventricular activation (DPVA) in coronary heart disease (CHD) and their relation to ventricular tachycardia and/or fibrillation (VT/VF). No DPVA could be recorded in normal subjects (n = 25) or in patients with various cardiopathies with VT/VF but without CHD (n = 10). DPVA have been recorded only in patients with CHD (n = 50) (all patients having undergone ventriculography and coronarography). The prevalence of DPVA is 12.5% without VT/VF, 50% with VT/VF, and 80% when these arrhythmias are associated with the presence of a ventricular aneurysm. The duration of the DPVA is also important, since it is only in the group with VT/VF and with aneurysm that the R-EVEA duration (interval between the peak of the R wave and the end of electrical ventricular activity) exceeds 100 ms. DPVA disappeared in all the cases after aneurysmectomy. The DPVA, when of long duration, can be considered a hallmark of serious ventricular arrhythmias in patients with CHD and a ventricular aneurysm.

[Endocavitary electric exploration in the study of auricular dysrhythmias]. / Contribution de l'exploration électrique endocavitaire à l'étude de la dysrythmie auriculaire

His bundle recording combined with atrial pacing permit to evaluate atrio-ventricular conduction and the function of the sinus node by measuring the corrected sinus recovering time (CSRT). Three groups of 10 patients are included in this study: -- Group I is composed of control patients; the CSRT varies between 30 and 450 msec (mean value : 320 msec +/- 123.3). Neither atrio-ventricular nor intraventricular block was observed during His bundle recording combined with atrial pacing. -- Group II, composed of patients with atrial dysrhythmia has a CSRT varying from 720 to 5.900 msec (mean value: 2.750 msec +/- 184.5). Six of these patients have atrio-ventricular conduction disturbances. -- In group III all patients had atrio-ventricular or intraventricular conduction defects without atrial dysrhythmia. CSRT varies between 205 and 510 msec (mean value: 310 +/- 88.6). The authors conclude that atrial dysrhythmia is probably an original degenerative disease which is different from the "Lenègre" disease, by his incidence, the location of the lesions and the clinical issue. This conclusion is made by comparing the results of the authors with the analysis by James of the embryogenesis of the sinus node and of atrial and atrio-ventricular pathways.

Sinus node function and conduction system after complete repair of tetralogy of Fallot.

Twenty-three children underwent electrophysiological studies during routine postoperative catheterization two months to five years after complete correction of tetralogy of Fallot. The aim of the study was to investigate the whole conduction system, including sinus node function, suing His bundle recordings and atrial pacing. H-V intervals were normal at rest and with pacing in twenty-two patients, including four patients with evidence of bifascicular block on the surface ECG. One patient with cardiomegaly and evidence of diffuse myocardial damage had a prolonged H-V interval but did not develop a block at this level during pacing A-H interval was slightly prolonged in four patients and normal in all others. The threshold of pacing-induced atrioventricular block ranged from 75 to 240/min and was somewhat age dependent (r = -0.55). Two patients fell below the 95% confidence limit of this regression and are considered abnormal. One returned to normal after intravenous injectionof atropine. Corrected sinus node recovery time ranged from 60 to 2000 msec. Three patients had values above 500 msec which are considered abnormal. These patients had other minor signs of sinus node dysfunction, i.e., episodes of sino-atrial block at rest or intermittent sinus bradycardia. Thus, while the His Purkinje system performed satisfactorily in all patients, sinus node dysfunctional and A-V node dysfunction were demonstrated in a few patients after correction of tetralogy of Fallot.

[Percutaneous selective coronarography. Apropos of 600 cases]. / La coronarographie sélective percutanée. A propos de 600 examens

600 selective coronary angiographies were performed in 559 patients, using Judkins preformed transfemoral catheters. One fatality was deplored (mortality: 0,17 p. 100). 15 cardiac complications were observed 2,5 p. 100), 10 of which were severe but rapidly corrected arrhythmias. Among these 559 patients 495 were clinically cases suffering from probable or certain coronary heart disease. 88 p. 100 of this group were men. Selective coronary angiography revealed stenosis with decrease of at least 50 p. 100 of the lumen in over 80 p. 100 of the cases. The anterior descending was the most frequent site of stenosis. In the majority of cases, and especially in men, two or several vessels were diseased. There is some relationship between the development of collateral circulation and the extension of coronary disease. In one third of the cases, ventricular function, assessed by measurement of the ejection fraction was impaired.