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Biomedical subjects

H Bricaud

Publications and source records attributed to H Bricaud.

At least 91 records · Page 5Linked to original sources
PubMed1983

Megakaryocytes separation in homogeneous classes by unit gravity sedimentation: physico-chemical, ultrastructural and cytophotometric characterizations.

Separation by velocity sedimentation at unit gravity according to the STAPUT system of Miller and Phillips was applied to a population of rabbit megakaryocytes previously enriched by density gradient centrifugation. By this means, 80,000 to 100,000 megakaryocytes with 100% purity were collected in eight fractions according to size for a sedimentation velocity of 52 to 30 mm/hr. DNA-Feulgen cytophotometric measurements show significant correlation between megakaryocyte size and ploidy. The study of the eight purified fractions is of particular interest because it reflects megakaryopoiesis evolution. The different stages of megakaryocyte maturation of each fraction were analysed by transmission and scanning electron microscopy and were correlated to ploidy level. Thrombopoietic megakaryocytes with grape-like appearance were found in ploidy fractions 8n to 128n. Cytophotometric determinations of nucleohistones revealed several populations.

Animals↗
PubMed1983

[Comparative study of quinidine and disopyramide in the treatment of stable ventricular extrasystole].

The antiarrhythmic efficiency of quinidine arabogalactan-sulphate (QAGS) and disopyramide were determined in 38 patients showing chronic, stable frequency premature ventricular beats (PVB). The study which was carried out in 4 medical Centers, used a longitudinal cross-over design. After a baseline evaluation which consisted of two 24 hours electrocardiograms, the patients were randomised to one of the two drugs during a period of 6 or 7 days. The drug sequence were followed by a placebo sequence. A 24 hours electrocardiogram was performed at the end of each sequence. The daily doses were equivalent to 660 mg of quinidine base for QAGS and 600 mg for disopyramide. Among the 38 patients who entered in the study, 32 went through each sequence of the test. The average number of PVB was significantly reduced by QAGS and disopyramide (p less than 0.0001). With QAGS 18 patients had more than 65 p. 100 reduction of PVB and 12 of them more than 80 p. 100. With disopyramide, 14 patients had more than 65 p. 100 reduction of PVB and 12 of them more than 80 p. 100. There was no statistical difference in the overall efficiency of the two drugs. Three patients died, one from myocardial reinfarction, one from ventricular fibrillation; in one other case, the cause of the death remained undetermined. QAGS was better tolerated than disopyramide; adverse effects occurred in 6 patients with QAGS and in 10 with disopyramide. The responsibility of disopyramide in the occurrence of two severe ventricular arrhythmia may be questioned.

Adult↗
PubMed1983

[Difficulties and limits in the evaluation of the cost of coronary disease in France].

Evaluating the cost of coronary artery disease is difficult because it must take into account not only the cost of the disease process itself, but also that of prevention and research. 1. The cost of the disease process itself may be assessed by: a) an analytical study of the real cost of diagnostic and therapeutic procedures; b) a synthetic study of the procedures according to the clinical forms of the disease. Although this task is simple for a given patient, extrapolation of the results to a whole group of patients is more aleatory; c) an epidemiological study of the different forms of coronary artery disease: although global data is available the absence of a coronary artery disease register makes this a difficult problem; d) an evaluation of the socio-professional repercussions of coronary artery disease with integration of the cost and loss in gross national product. 2 The cost of prevention can be assessed by taking the following factors into consideration: a) cost of individual primary prevention which poses the problems of check-up examinations; b) cost of community primary prevention; c) cost of research including fundamental research on the atheromatous process and myocardial ischemia plus clinical research such as secondary prevention enquiries. In conclusion, it appears that: --it is difficult to determine the cost of coronary artery disease without a specialist register; --the cost of coronary artery disease should be considered from positive (source of economic activity) and negative points of view (socio-professional repercussions); --a reduction in the cost of coronary artery disease requires a deeper understanding of the disease, better prophylaxis and socio-professional rehabilitation, and improved organisation of exciting health structures.

Adult↗
PubMed1983

[Sequential double demand programmable stimulation in the treatment of resistant supraventricular tachycardia. Long-term results].

Asynchronous pacing at a rhythm slower than that of the tachycardia (underdrive) is an established procedure for the reduction of supraventricular tachycardia. Simultaneous or sequential stimulation depolarising two parts of the circuit (atrium and ventricle) has a greater chance of reducing the tachycardia than stimulation of a single chamber. Five patients with supraventricular tachycardia resistant to antiarrhythmic therapy were treated by sequential pacing in the underdrive mode. Electrophysiological investigations showed a bundle of Kent to be responsible for the ECG appearances of Wolff-Parkinson-White (3 cases) with retrograde conduction only (concealed WPW) in 2 cases. One patient was able to put a stop to his attacks by the application of a magnet over the pulse generator. In four patients, a newly designed pulse generator, based on this concept, was implanted with the property of automatic detection of tachycardia (defined as a heart rate faster than 150/min) triggering almost simultaneous pacing of the coronary sinus and right ventricle (sequential interval of 65 ms) in the asynchronous mode at 77 bpm. The results were reviewed with a follow up of 6 to 36 months. This pulse generator was shown to be effective in both the reduction and prevention of episodes of supraventricular tachycardia. Sequential double demand pacing is a valuable and useful method of treating reentrant tachycardias associated with the WPW syndrome or concealed Kent bundles. It provides an alternative to surgery when the effective refractory period of the Kent bundle is long. Present advances in the field of cardiac pacing will probably result in a widening of the indications for this mode of therapy.

Adult↗
PubMed1983

[Complexes of "pancreatic elastase-seric inhibitors" in swine: their behavior in the presence of homologous aortic elastin].

The present paper deals with the particular behavior of the complexes formed between pancreatic elastase and seric inhibitors in the Pig, when they were set in contact with homologous elastin. The previously known values of dissociation constants of alpha 1-antiprotease-elastase and alpha 2-macroglobulin-elastase complexes indicated they were very stable and almost irreversible. Nevertheless, our results suggest that, when the overall complexes between porcine pancreatic elastase and seric inhibitors were isolated in non drastic conditions, they might develop an elastolytic activity against elastin fibers. This result is important as regards atherosclerosis--in Human--where a destruction of elastin is involved at a early stage of the disease.

Animals↗
PubMed1983

[Functional content of the electrocardiogram of coronary patients].

A comparison of the haemodynamic and electrocardiographic data was carried out in 180 coronary patients. All underwent catheterisation and coronary angiography for angina. They were divided into three main groups: 53 patients with coronary atheroma without significant stenosis; 43 patients with at least one coronary stenosis greater than 50%; 84 patients had myocardial infarction with ECG changes of transmural necrosis and coronary thrombosis (or greater than 80% stenosis). Parameters of left ventricular function (LVF), especially ejection fraction (EF), systolic work (LVESW), end diastolic pressure (LVEDP), end diastolic volume (LVEDV), myocardial mass calculated from angiography (LMV) and volumic compliance were analysed in all cases. Each patient had at least 5 ECG recordings analysed by a HP 6 calculator which determined the values of the principal numeric ECG parameters and the means of the 5 recordings. Particular attention was given to the sum of the R waves in the 12 leads (sigma R mV) and Macruz's index (duration of P/PR - P in Lead II). A satisfactory correlation was found overall between sigma R and EF (r = 0,45, p less than 0,001). sigma R was the only ECG variable related to LVF in patients without infarction. In this group of 96 patients, sigma R correlated with LVEDV (r = 0,46, p less than 0,001) with LVM (r = 0,46, p less than 0,001), with LVESW (r = 0,52, p less than 0,001). There was a discordance between angiographically measured LVM and the mass of electrically active myocardium in patients with infarction. sigma R was independent of LVM, LVEDV, and LVESW.(ABSTRACT TRUNCATED AT 250 WORDS)

Arteriosclerosis↗
PubMed1983

[Demonstration of elastinolytic activity in blood or plasma].

The complexes between "elastases" and their seric inhibitors (a. 1. AP and a2. M) which could be formed in the blood, are exhibited in vitro: after incubation of serum or plasma with 125iodine labelled elastin at pH = 6, followed by extensive washing, pH was increased from 6 to 8.6: labelled peptides are released in supernatant.

Animals↗
PubMed1983

[Detection of coronary atherosclerosis before 45 or 50 years of age. Value of skin biopsy].

A three year prospective study was undertaken to determine the possible relationship of coronary atherosclerosis in subjects under 50 years of age, confirmed by coronary angiography, and structural changes of the connective tissue dystrophy. The independence of the histological changes with respect to other cardiovascular risk factors was also evaluated. The study was carried out by a double blind technique between the histological and clinical results. We present our preliminary results in 88 male patients, 64 with atherosclerosis and 24 controls. Histological abnormalities were found in 81.25% of patients with atherosclerosis compared to 33.3% in the control subjects. Accelerated skin aging, a simple diagnosis, requires only light microscopy for diagnosis and seems to be the simplest and most reliable screening test. It is found in 61% of atherosclerotic patients in the general population and in 74% of coronary patients under 45 years of age, independently of other risk factors especially cigarette smoking. As a screening test for coronary atherosclerosis before 45 years of age, the sensitivity was found to be 74.2% and specificity 57.1%, the predictive value being 79.3%. Connective tissue dystrophy needs electronic microscopy and seems to be less reliable in the detection of atherosclerosis as this condition is usually found in patients over 45 years of age. However, these changes are related to atherosclerosis and not to age. This study shows that skin biopsy in the search of accelerated skin aging, enables atherosclerosis to be detected simply and reliably, independently of other risk factors. This test, by defining the individual structural risk, is a method of following the progression or regression of atherosclerosis and so help control treatment.

Adult↗
PubMed1982

Influence of cell density on collagen biosynthesis in fibroblast cultures.

Characteristic features of collagen metabolism in human skin fibroblasts were studied in relation to cell density. Measuring peptide-bound hydroxyproline we found that collagen synthesis per cell decreased when cultures approached confluency. On the other hand, the relative rate of collagen synthesis (collagen/total protein) was higher in quiescent than in proliferating cultures. With increasing cell density the proportion of type III collagen in comparison with type I was found to be slightly increased. In addition, in low-density cultures [alpha I(I)]3 collagen trimers were produced in considerable amounts, whereas they were no longer detected in cultures with a high cell density. Although hydroxylation of proline residues was normal in all cell stages, conversion of procollagen into collagen was found to depend strongly on the density at which the cells were investigated. Almost no cleavage of procollagen peptides was observed in rapidly growing cells, whereas highly confluent cell cultures converted most of the newly synthesized procollagen molecules.

Cell Count↗
PubMed1982

The human blood platelet: a cellular model to study the degradation of thymidine and its inhibition.

Intact platelets catabolize extracellular thymidine into thymine. Studies of the concentration dependent degradation of thymidine by intact platelets indicate a Michaelis mechanism with an apparent Km of about 0.12 mM and a Vmax of 2.5 nmoles/min for 3 X 10(8) platelets. This degradation process is inhibited by various nucleosides, pyrimidine bases and C-5 or C-6 substituted uracils. Cytidine, deoxycytidine, adenosine and deoxyadenosine seem to inhibit thymidine degradation by reducing the intracellular transport of thymidine. Uridine inhibits both the thymidine transport and the activity of the phosphorolytic enzyme, thymidine phosphorylase (EC 2.4.2.4). Some substituted uracils are specific inhibitors of thymidine phosphorylase activity. 6-Amino-5-bromouracil, the most active of them, either with acellular extracts or purified thymidine phosphorylase, is also the best inhibitor of thymidine degradation in intact human platelets. Platelets constitute a new model to study the efficiency of specific inhibitors on thymidine catabolism in an 'human intact cell' which contains only one pyrimidine nucleoside phosphorylase, the thymidine phosphorylase.

Biotransformation↗
PubMed1982

Decreased prostaglandin production in cultured smooth muscle cells from atherosclerotic rabbit aorta.

Prostaglandin synthesis in aortic smooth muscle cells originating from healthy an atherosclerotic rabbits was studied by incubating [14C]arachidonic acid with intact confluent cells and cell homogenates. In spite of a reduced 6-keto prostaglandin F1 alpha formation, no potentiating effect on the prostaglandin E2 generation occurred. Indeed, both cyclooxygenase and prostaglandin I2 synthetase activities appear to be reduced. These results suggest that an impaired arachidonic acid utilisation in aortic smooth muscle cells may be involved in the course of the atherosclerotic process.

Animals↗
PubMed1982

Bidirectional tachycardia. Mechanism derived from intracardiac recordings and programmed electrical stimulation.

His bundle recordings and programmed electrical stimulation were performed in a 70-year-old woman with bidirectional tachycardia; the recordings demonstrated the infra-Hissian origin of the tachycardia. Occurrence of the His deflection slightly after the onset of ventricular depOlarization suggested that the origin of the tachycardia was located near the His bundle bifurcation. Recording of three atrial sites during tachycardia allowed the study of retrograde atrial activation. Two sets of fairly constant and alternating VA intervals were recorded. This fact is consistent with two ventricular circuits used alternatively. The tachycardia could also be interrupted with a single atrial or ventricular premature beat. It is postulated that the tachycardia is due to macroreentry involving the two fascicles of the left branch. This study suggests that reentry may be a possible mechanism in some cases of bidirectional tachycardia.

Aged↗
PubMed1982

[Coronary flow in experimental cardiac hypertrophy caused by arterial hypertension].

We studied the effects of left ventricular hypertrophy (LVH) induced by one clip-two kidney Goldblatt hypertension on coronary circulation of conscious rats. Twenty four weeks after clipping, coronary blood flow per unit mass after pharmacological dilation by carbochrome (6 mg/kg) (coronary flow reserve-CFR) was measured using radioactive microspheres. Coronary flow reserve remained normal either during development or LVH in untreated rats or after reversal of LVH in rats treated with captopril or nephrectomy. An appropriate relationship between pressure and mass, which varied in parallel, layed a significant role in maintaining a normal CFR. This, if confirmed in man, our results would suggest that antihypertensive drugs that alter this relationship by decreasing pressure but not LV mass may adversely affect CFR.

Animals↗
PubMed1982

[Mitral valve prolapse: do rhythm disorders have an electrophysiologic substratum?].

The mechanism of arrhythmias in mitral valve prolapse (MVP) is still unclear. The aim of this study was to determine if there were electrophysiological features common to patients with MVP. Eighteen patients with MVP documented on echo and angiocardiography underwent electrophysiological investigation. The series comprised 5 patients with ventricular arrhythmias and 5 with supraventricular arrhythmias, two of whom had ECG appearances of the Wolff-Parkinson-White, syndrome, and one a short PR interval. The RR interval, PR interval, intraatrial conduction (PA), atrio-hisian conduction (AH), intraventricular conduction (HV) the effective refractory periods of the atrium, AV node and ventricle, and the corrected sinus node recovery time were measured in the MVP group and in 20 presumed normal control subjects. There was a significant increase in the PR interval (p less than 0,05) at the expense of nodal conduction (AH) in the MVP group. In addition the Wenckebach point was significantly lower in this group. The other electrophysiological parameters in spontaneous rhythm and the atrial, AV nodal and ventricular refractory periods were the same in both groups. Sinus node function was comparable in both groups. In two patients without paiviously documented tachycardia, junctional tachycardia was initiated by provocative stimulation. However, no ventricular arrhythmias could be induced by pacing. A large number of preexcitation syndromes was observed in the MVP group (4/18), including one case of a latent Kent bundle, in patients with paroxysmal supraventricular tachycardias. On the other hand, the value of electrophysiological investigation seems to be limited for clarifying the mechanisms of the ventricular arrhythmias, probably because of their endomyocardial origin. Nevertheless, hemodynamic investigation showed abnormalities of left ventricular contraction in 4 of the 5 patients with ventricular arrhythmias.

Adolescent↗