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Biomedical subjects

B Perrot

Publications and source records attributed to B Perrot.

At least 37 records · Page 2Linked to original sources
PubMed1983

[Criteria of operability for advanced valvular diseases].

Despite the advances made in cardiac surgery, there are still some cases of valvular disease which remain inoperable, i.e. patients who present an operative risk which is too high in relation to the natural history of the disease. A study of the literature does not enable us to define objective clinical or investigational parameters of inoperability, but only factors of poor prognosis. Although there does not appear to be any cardiac contra-indications to valve replacement in cases of advanced valvular disease, the authors stress the importance of the patients general condition which determines the post-operative prognosis and the need for a better definition of the criteria of poor prognosis so that surgery can be performed before it is too late.

Echocardiography↗
PubMed1982

Characterization of monofunctional chorismate mutase/prephenate dehydrogenase enzymes obtained via mutagenesis of recombinant plasmids in vitro.

Mutagenesis in vitro has been used to obtain mutant forms of the bifunctional enzyme, chorismate mutase/prephenate dehydrogenase. Plasmid DNA containing the genes that code for the enzyme was treated with hydroxylamine and the resulting products were used to transform strains of Escherichia coli. Two types of mutant were isolated. One contained enzyme which was mutase-positive, dehydrogenase-negative while the other did not exhibit either activity. Kinetic and physical analysis of one of the purified monofunctional enzymes showed that the loss of dehydrogenase activity was due to modification of the binding site for NAD. The results open the way for molecular studies of structure-function relationships with this bifunctional enzyme.

Chemical Phenomena↗
PubMed1982

[Effect of adenosine triphosphoric acid (ATP) on accessory conduction bundles].

The effects of an injection of 40 mg of ATP were studied in 48 subjects with an overt or latent preexcitation syndrome. The results showed that the slowing of anterograde or retrograde conduction by ATP was not specific for nodal conduction. This phenomenon was observed in conduction through Kent bundles with long refractory periods and the possibility of preexcitation due to the association of James and Mahaim fibres should also be considered.

Adenosine Triphosphate↗
PubMed1982

[Danger of sinoatrial block and the use of antiarrhythmic agents in myocardial infarcts].

Nine cases of major ventricular arrhythmia (tachycardia (VT), fibrillation (VF), torsades de pointe) are reported in patients with sequellae of myocardial infarction but without residual angina or cardiac failure. --Six of these disturbances of excitability occurred after a bradycardia due to sino atrial block (SAB) which favoured the breakthrough of abnormal automatic foci. This form of the bradycardia-tachycardia syndrome was demonstrated by endocavitary electrophysiological exploration.. These were the only cases of major ventricular arrhythmia observed in a series of 88 SABs. Reputedly benign, they illustrate the potential gravity of a conduction defect in patients with sequellae of myocardial infarction. --Three other cases of abnormal ventricular excitability complicating the administration of 1 mg/kg of Ajmaline to test for paroxysmal block after myocardial infarction. These were the only cases of VT observed in a series of 800 Ajmaline tests. The three patients have had no further episodes of VT after 1 year's follow-up. On the other hand, in 43 Ajmaline tests without VT in patients with myocardial infarction, 6 cases of VT and 1 lethal VF were later observed. This demonstrates the lack of significance of episodes of VT during Ajmaline tests, the depressant action of the drug on intracardiac conduction favouring the initiation of reentry. In conclusion, a history of myocardial infarction exposes the patient to the risk of major ventricular arrhythmias in SAB, the detection of which should indicate pacemaker therapy from the first symptoms. The use of an intravenous antiarrhythmic agent should be avoided as it may aggravate arrhythmias. However, the arrhythmia is of no prognostic significance.

Aged↗
PubMed1982

[Arterial spasm of the lower limbs caused by pheochromocytoma].

The authors report the case of a 66-year-old man hospitalised with a clinical picture of stage III arterial disease of the lower limbs. Aortography revealed complete spasm of both popliteal arteries and a right adrenal tumour. Excision of the phaeochromocytoma led to the disappearance of symptoms of obliterative arterial disease and normalisation of Doppler results. The role of catecholamines in spasm is discussed.

Adrenal Gland Neoplasms↗
PubMed1981

The structure of the gene for the large subunit of ribulose 1,5-bisphosphate carboxylase from spinach chloroplast DNA.

A cloned fragment of spinach chloroplast DNA carrying the gene for the large subunit of ribulose bisphosphate (RuBP) carboxylase has been analysed by electron microscopy of R-loops, by hybridization to Northern blots of chloroplast RNA, by S1 nuclease mapping and by DNA sequencing. The transcribed region of the gene is 1690 +/- 3 nucleotides long and co-linear with its mRNA. It comprises a 178-179 bp 5' untranslated sequence, a 1425 bp coding region and an 85-88 bp 3' untranslated region. The deduced sequence of the 475 amino acids of the spinach large subunit protein shows 10% divergence from that of the maize large subunit protein (1). The nucleotide sequence divergence between spinach and maize over the same coding region is 16% but in the transcribed flanking regions it is 35%. Features of the spinach chloroplast gene which resemble those of bacterial genes include a 5-base Shine-Dalgarno sequence complementary to a sequence near the 3' end of chloroplast and bacterial 16S rRNA, a promoter region partially homologous to a consensus sequence of bacterial promoters, and a transcription termination region capable of forming a typical stem and loop structure.

Amino Acid Sequence↗
PubMed1981

[Values of the effective anterograde refractory period of the bundle of His].

The effective refractory period of the His bundle (ERP.H), the longest H1, H2 interval not followed by a V2 ventricular complex, was measured in 45 cases during the electrophysiological investigation of 500 Patients by premature atrial stimulation techniques. The patients were divided into two groups according to the result: Group I: 22 patients with syncope, a spontaneous HV interval greater than 60 ms, greater than 100 ms after Ajmaline or infrahisian block with atrial pacing at less than 150 bpm. Group II: 23 patients without these abnormalities. The ERP.H was significantly different (p less than 0,001) in the two groups with valves greater than 400 ms in Group I and less than 400 ms in Group II. It is suggested that in the absence of other electrophysiological abnormalities an ERP.H of 400 ms or over may be an indication for permanent pacing in patients with Stokes-Adams attacks. The finding of an ERP.H of over 400 ms is associated with severe infrahisian block. However, the ERP.H depends on the ERP of the AV node which must be shorter to calculate the refractory periods of the His bundle, and, above all, on the basal sinus cycle. The ERP.H decreases with shorter sinus cycles and cannot be calculated when the sinus cycle is less than 600 ms. Conversely, the critical value of 400 ms is not valid for cycles longer than 1000 ms as cycles of that length are associated with lengthening of the ERP.H. The regression of infrahisian block during programmed atrial pacing after Atropine does not seem to be a reliable method of distinguishing between physiological and pathological atrioventricular block.

Ajmaline↗
PubMed1981

[Prognosis of chronic post-traumatic thoracic aorta aneurysms in 15 patients (author's transl)].

False chronic post-traumatic aneurysms of the ascending aorta were detected in 15 patients. These aneurysms were false because only a few cells were present in their walls: it is only after survival for more than 3 weeks tht one can speak of chronic aneurysms, and only 5% of the injured patients survived for this period of time. The lesions show marked progression for one year, but rupture of apparently quiescent aneurysms may occur up to 20 years after the initial injury. The prognosis of these lesions is therefore comparable with that of other aortic aneurysms. Cardiovascular surgery has progressed to such an extent, and the risks are so low (0% in this series), that surgical correction should be systematically considered.

Adolescent↗
PubMed1979

[Systematic study of ventriculo-auricular conduction and its importance in the detection of aberrant conduction pathways].

Ventriculo-atrial conduction was studied by ventricular pacing in three groups of patients: 34 cases with the preexcitation syndrome on surface ECG, 35 cases with documented paroxysmal atrial tachycardia but with otherwise normal ECGs and 120 cases without either of these two conditions. This conduction time was unchanged up to pacing rates of over 160/min in 88 p. 100 cases with preexcitation and was thus a sign of a nodal short-circuit. This phenomenon was also observed in 85 p. 100 cases with isolated paroxysmal atrial tachycardia and in 20 p. 100 normal cases which suggests the presence of a latent accessory pathway in these patients.

Adolescent↗