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Biomedical subjects

G Leroy

Publications and source records attributed to G Leroy.

At least 19 recordsLinked to original sources
PubMed1992

[Should coronary angiography be practiced in patients with recent myocardial infarction?].

As a rule, infarction results from an occlusive thrombosis in a pre-existing atherosclerotic stenosis. Contrary to intravenous thrombolysis, coronary arteriography with immediate removal of obstruction can only be performed in a minority of patients. Similarly, "salvage angioplasty", performed if thrombolysis has failed, does not justify early coronary arteriography, except in certain cases of infarction at very high risk. In 80% of the cases the first days are uneventful, but the mortality in the first year (about 10%) will depend upon the presence or absence of latent residual ischaemia and/or left ventricular dysfunction. A noninvasive evaluation carried out before the patient is discharged and including clinical and echocardiographic data as well as the results of stress tests (sometimes coupled with isotopic studies) may isolate an important group of patients (40%) whose mortality rate at one year is below 3%. Systematic coronary arteriography, therefore, is not justified, especially since it facilitates the "easy" decisions of angioplasty the benefits of which has not been demonstrated in the absence of residual ischaemia during exercise.

Coronary Angiography↗
PubMed1992

Biochemical and spectroscopic characterization of the high molecular weight cytochrome c from Desulfovibrio vulgaris Hildenborough expressed in Desulfovibrio desulfuricans G200.

The gene of high molecular weight, multiheme cytochrome c (Hmc) from the sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough has been overexpressed in Desulfovibrio desulfuricans G200. The recombinant protein has been purified. Its molecular weight (65,600), amino acid composition, and NH2-terminal sequence were found to be identical to those of the wild-type protein. The recombinant protein has been spectroscopically characterized (optical spectrum, EPR, circular dichroism) and compared to the wild-type protein. We have found 16 hemes per molecule by iron analysis and the pyridine hemochrome test. Both high- and low-spin features were observed in the EPR spectrum. A detailed spin quantitation analysis indicates 1 or 2 high-spin hemes and 14 or 15 low-spin hemes per molecule. The redox potentials of the hemes determined by voltammetric techniques gave an average of three different values, 0, -100, and -250 mV (versus NHE), for the wild-type and the recombinant cytochrome. The low potential values are similar to the values observed for the bis(histidinyl) coordinated hemes of cytochrome c3. A comparison of the arrangement of heme binding sites and coordinated histidines in the amino acid sequences of cytochrome c3 and Hmc has shown that the latter contains four domains, three of which are complete c3-like domains, while the fourth represents an incomplete c3-like domain which may contain His-Met coordinated hemes. These data are in agreement with the detailed study of the number and types of hemes reported in this paper.

Amino Acid Sequence↗
PubMed1992

[Cardiac tamponade and central venous catheterization].

A 32-year-old female patient was operated on for a residual colonic stricture occurring after hemicolectomy. A right internal jugular central venous catheter was inserted during the anaesthetic for postoperative parenteral feeding. The anaesthetic combined both general and epidural anaesthesia, the latter being continued for postoperative analgesia (10 ml.h-1 of 0.125% bupivacaine). Two days later, the patient complained of sudden chest pain, with restlessness, tachycardia, cyanosis, resulting in ventricular tachycardia and cardiac arrest. When admitted to the surgical intensive care unit, the patient was in deep coma and had nonsustained ventricular tachycardia, a left haemopneumothorax and a pneumopericardium. The patient died before a definitive diagnosis was made. Postmortem examination revealed an ulcerated anterior pillar of the tricuspid valve, as well as a perforation of the right ventricle and a communication between the pericardium and the left pleural cavity. The diagnosis and treatment of this rare life-threatening complication may be very difficult. It prevention consists in using short catheters for internal jugular venous access, and checking the tip's position radiologically by opacifying the catheter.

Adult↗
PubMed1992

[False aneurysm of the left ventricle during the acute phase of myocardial infarction: diagnosis by transesophageal echocardiography].

The authors report a case of myocardial infarction complicated by a false aneurysm of the posterior wall of the left ventricle, the diagnosis of which was confirmed, for the first time, by transesophageal echocardiography (TEE) which provided better definition of the anatomical features of the lesion: visualisation of the particularly wide neck (5 cm) and the site of rupture of the myocardium; demonstration of the presence in the false aneurysm with a thin pericardial wall of a large thrombus of different acoustic density, itself overlain by swirling whorls. Colour Doppler combined with TEE clearly showed the acceleration of flow at the neck and its slowing in the newly formed cavity. Once the diagnosis was made, the patient rapidly underwent surgery with a successful outcome. The quality of the images obtained without risk by TEE suggests the important role which this investigation could play in the future in the diagnosis of certain mechanical complications of myocardial infarction.

Diagnosis, Differential↗
PubMed1992

[Evaluation of treatments with beta-blockaders after myocardial infarction].

Beta-blockers have been used after myocardial infarction since 1965: however, it was not until the beginning of the 80s that the large multicentre clinical trials published results showing clearly their beneficial effects and leading to their widespread usage: betablockers significantly reduce the medium term (1 to 3 years) risk of death (-22 to -24%), especially sudden death (-32%) and the frequency of recurrent infarction (-27%). The cardio-protection so obtained is multifactorial, essentially related to their antiarrhythmic, antiischemic and antihypertensive effects. It has been established that beta-blockade should be instituted as soon as possible in the hours following the infarct (intravenous relayed by oral administration) and may be useful associated with aspirin. Although the large scale clinical trials did not determine the optimal dosage or the duration for which treatment should be administered, they did show that the groups of high risk patients were those to benefit the most from this therapy. Beta-blockers are usually well tolerated. However, it must be pointed out that 18% of patients were excluded from the two principal trials (only 25 to 30% of infarct patients were included) because of contraindications to beta-blockers and that 25 to 30% of the patients initially included had to interrupt the treatment because of side effects.

Adrenergic beta-Antagonists↗
PubMed1992

[Delayed autologous transfusion in prosthetic surgery of the hip and knee].

Blood sparing methods used during hip or knee prosthesis implantation or change in 360 patients during the years 1990-1992 were evaluated. For delayed transfusion of autologous blood the main counter-indication was unstable cardiovascular condition. Such cases being excluded, the method was used in 64.2% of all cases. No homologous blood was needed in 68.9% of patients. This result was obtained in 55% of the cases by delayed transfusion of autologous blood and in 13.9% by peroperative normovolaemic haemodilution.

Adult↗
PubMed1992

[Electrocardiogram during the initial period of myocardial infarction: a tool of therapeutic decision].

The electrocardiogram (ECG) remains the basic investigation for the diagnosis of acute myocardial infarction. The decision to institute intravenous thrombolytic therapy, which has revolutionised the treatment of myocardial infarction in recent years, requires the presence of ST segment elevation and a suggestive clinical history. Early Q waves and reciprocal ST changes may be helpful. The value of thrombolytic therapy has not been demonstrated in patients without ST elevation, especially considering the usually favourable prognosis of infarcts with normal ECGs or with only non-specific repolarisation changes. The initial ECG provides information about infarct size which is an essential prognostic factor. This evaluation is based on the topography (anterior or inferior), the amplitude of ST elevation and the number of leads in which these changes are observed. The initial analysis has two objectives: to evaluate the risk/benefit ratio of treatment in cases of relative contraindications to thrombolysis or with a doubtful diagnosis; to select high risk patients (extensive infarcts) who may benefit from "salvage angioplasty" in the event of failure of thrombolysis: coronary angiography should be programmed from the onset as the ECG outcome does not allow prediction of the results of thrombolysis for the majority of these patients.

Decision Support Techniques↗
PubMed1992

[Negativity of the exercise thallium test despite tight stenosis of the common trunk of the left coronary artery].

The authors report a case of severe angina linked to subocclusive ostial stenosis of the common trunk of the left coronary, characterised by the contrast between a very positive stress test on the basis of clinical and electrocardiographic parameters and a negative Thallium stress test. The occasion is taken to review the sensitivity of Thallium stress testing in lesions of the common trunk.

Constriction, Pathologic↗
PubMed1991

Identification of the site of interaction between cytochrome c3 and ferredoxin using peptide mapping of the cross-linked complex.

Structural studies carried out on a cross-linked complex between cytochrome c3 and ferredoxin I, both isolated from Desulfovibrio desulfuricans Norway, allowed the identification of the site of interaction between the two redox proteins. Staphylococcus aureus proteinase and chymotrypsin digestions led to characterization of peptides containing both cytochrome c3 and ferredoxin sequences. The cytochrome c3 sequences involved in the three isolated cross-linked peptides contained several lysine residues localized around the heme 4 crevice. This analysis stressed the peculiar role of lysines 100, 101, 103, 104 and 113, which could be considered as major cross-link sites, as opposed to the lysines 75, 79 and 82, which could be considered as minor cross-link sites. One cross-linked peptide, containing two ferredoxin sequences joined to one cytochrome c3 sequence, had been isolated, suggesting the possibility of more than one cross-link per covalent complex. All these results led to the identification of heme 4 of cytochrome c3 as the site of interaction for the ferredoxin I. This study confirms the proposal that could be deduced from the hypothetical structure of the complex built by computer graphics modelling (Cambillau, C., Frey, M., Mosse, J., Guerlesquin, F. and Bruschi, M. (1988) Proteins: struct., funct. genet. 4, 63-70).

Binding Sites↗
PubMed1991

[Unstable angina and infarction without Q wave treated with verapamil: value of the early exercise test].

Twenty patients aged 56.8 +/- 10 years, hospitalised for unstable angina (12 cases) or infarct without Q wave (8 cases) were treated with IV heparin, aspirin and oral verapamil. The clinical syndrome was controlled by verapamil in 16 cases out of 20 (80% of cases) at the dosage of 360 mg/d in 14 patients and of 480 mg/d in two. An exercise ECG, limited by symptoms, was obtained in 18 patients (90%) between the 8th and 12th day. Coronary arteriography was considered to be indicated in three sets of circumstances: recurrence of angina resistant to nitroglycerin, positive exercise ECG with verapamil, persisting despite triple therapy or strongly positive exercise ECG (total duration less than or equal to 6 minutes). An infarct complicated the early course in 4 patients (20%): twice following angioplasty, once following exercise ECG (spastic angina) and once during triple therapy (refractory angina). Hospital and mid-term (18 +/- 6 months) mortality was nil. With verapamil, the absence of recurrence of angina together with a negative exercise ECG enabled the identification of a large group of patients (40%) with a low risk of a subsequent major accident and in whom early and routine coronary arteriography is probably not indispensable.

Adult↗
PubMed1990

The nucleotide sequence of the Desulfovibrio gigas desulforedoxin gene indicates that the Desulfovibrio vulgaris rbo gene originated from a gene fusion event.

Expression of the rbo gene from Desulfovibrio vulgaris Hildenborough in Escherichia coli minicells and Western blotting (immunoblotting) of Desulfovibrio cell extracts with antibodies raised against a synthetic peptide indicated the presence of a 14-kDa polypeptide product, as expected from the gene sequence. Cloning and sequencing of the gene (dsr) for desulforedoxin, a 4-kDa redox protein from Desulfovibrio gigas, showed that it is formed by expression of an autonomous gene of 111 bp, not by processing of a 14-kDa protein. The results indicate that the rbo gene product, which has a 4-kDa desulforedoxin domain as the NH2 terminus, may have arisen by gene fusion. Shuffling and fusion of genes for redox protein domains can explain the large variety of redox proteins found in sulfate-reducing bacteria.

Amino Acid Sequence↗
PubMed1988

[Angina at rest without significant changes in the per-critical ECG in coronary insufficiency].

In coronary patients angina pectoris at rest is usually attended by clear changes in repolarization, and in the absence of such changes clinicians are justifiably reluctant to assert that the constrictive chest pain is due to ischaemia. However, a number of concordant data indicates that in some cases myocardial ischaemia--whether spontaneous or induced by the ergonovine test or by coronary angioplasty--may cause an anginal pain that proceeds without significant alterations in repolarization and indeed, without any changes in ECG tracings. Prior to making a firm diagnosis of this type of angina, several causes of error must be excluded, the main one being that repolarization disorders are labile and may have disappeared whilst the anginal pain persists. But above all, the ischaemic episode that accompanies angina must be documented by haemodynamic, angiographic, scintigraphic or echocardiographic data. The pathogenesis of angina at rest occurring in coronary patients and without changes in per-critical ECG is still imperfectly known and probably complex. The authors review several possible mechanisms: the pain perception threshold may be lowered, the collateral circulation may be highly developed, and the ischaemic episode may be so discreet and/or controlled by treatment, or so evenly distributed between two opposite territories that no electric gradient is generated.

Angina Pectoris↗
PubMed1988

[Anomalies of the T waves induced by flecainide].

Flecainide is a class I antiarrhythmic agent which depresses depolarization and conduction velocities in myocardial and Purkinje's fibres, thereby extending their refractory period. As the drug belongs to the IC group, it may increase--moderately as a rule--the duration of QRS, but it does not alter the action potential duration and therefore does not increase the JT interval. In 3 patients treated with flecainide we observed a peculiar alteration in the shape of T waves, the peak of which was flattened and notched, forming a double hump. This abnormality, most clearly visible on precordial leads, remained isolated with no changes in other electrocardiographic parameters. It appeared independently of any circumstance likely to modify repolarization. It remained stable throughout treatment with flecainide and vanished when the drug was discontinued. It was regularly observed with the recommended therapeutic doses (200-300 mg/day) and was unaccompanied by signs of toxicity. To our knowledge, these T wave abnormalities have not yet been reported. Yet they deserve to be known and correctly interpreted, since they reflect impregnation of the myocardium by the antiarrhythmic agent which should not be withdrawn on this account.

Adult↗
PubMed1988

[Aneurysm of the interauricular septum].

In reference to three personal cases of interatrial septum aneurysm discovered on ultrasonography performed for the diagnosis of a cerebral embolism, the authors describe the positive diagnosis criteria, in mono- and bi-dimensional mode, of this abnormality, as well as related data obtained from catheterization, angiocardiography, and phonocardiography. This malformation, the frequency and pathogenesis of which still remain, today, difficult to evaluate, may be at the origin of complications, especially embolic migrations, systemic and also pulmonary, supraventricular rhythm disorders, interatrial shunt, reduced ventricular filling. Once established, the diagnosis is the subject of many controversies: if plain monitoring appears logical in asymptomatic forms, the occurrence of a systemic embolism makes it difficult to choose between surgical treatment and long-term anticoagulant therapy.

Aged↗