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Biomedical subjects

J Torresani

Publications and source records attributed to J Torresani.

At least 73 records · Page 4Linked to original sources
PubMed1984

[Parietal rupture of the heart in the acute phase of a postero-inferior myocardial infarction. Echocardiographic diagnosis, surgical cure].

A 58 year old patient with no previous cardiac history developed a postero-inferior myocardial infarction, complicated at the 6th hour by parietal rupture leading to acute tamponade. This was diagnosed by echocardiography which showed a compressive pericardial effusion containing large thrombi. Surgery under cardiopulmonary bypass was successful and led to good quality survival, maintained for over 6 months. A recent angiocardiographic control showed the absence of coronary artery lesions. This case is exceptionally rare and demonstrates the value of echocardiography in myocardial infarction complicated by sudden cardiovascular collapse. In addition, in this case, the haemorrhagic nature of the pericardial effusion was demonstrated by the visualization of thrombi in the pericardial space. Their presence would seem to be quite specific of parietal rupture.

Angiocardiography↗
PubMed1983

Triiodothyronine nuclear receptor. Role of histones and DNA in hormone binding.

The triiodothyronine (T3) nuclear receptor was previously shown to lose rapidly its high affinity hormone-binding property after a partial purification from the nuclear extract. It was then found that histones + DNA added to the incubation medium with labeled T3 could restore, at least in part, the high affinity T3 binding. We now demonstrate that DNA alone increases the high affinity T3 binding site concentration moderately, and only at low ionic strength where it can bind to the receptor. Total histones and all histone fractions studied (total core histones, F2a, H2B, H3, H4, H1) specifically increase, at low concentrations, the level of T3 binding; but higher concentrations of some individualized histones, particularly arginine-rich histones, have an inhibitory effect. DNA, or several other polynucleotides, in the presence of histones increase the stimulating histone effect and reverse the inhibitory effect into a true activation. Histones increase the number of T3 binding sites but decrease the affinity for T3; addition of DNA restores the high affinity for T3 and stabilizes the T3-receptor complexes. Thus, some of the histone molecules could play a role in the maintenance of the T3 binding site, but multiple interactions between histones or with DNA seem necessary to impair the negative effect exerted by other parts of the histone molecules. Whether these positive and negative effects of histones on the T3 binding site are of biological relevance in the regulation of T3 binding to its receptor remains to be determined.

Animals↗
PubMed1983

The effect of triiodothyronine on fatty acid synthetase activity and content in differentiating ob17 preadipocytes.

The effect of triiodothyronine on the activity and amount of the key lipogenic enzyme fatty acid synthetase was studied in differentiating preadipocyte cells (ob17) isolated from ob/ob mouse epididymal fat pad. In the presence of physiological concentrations of insulin, the acquisition of adipose morphology was accompanied by a parallel increase (10--15-fold) in synthetase specific activity and radioimmunoassayable amount relative to soluble cellular proteins. Inclusion of T3 at confluence significantly enhanced synthetase activity and content, with a maximum of 1.5--2-fold above controls at the physiological 1.5 nM concentration, whether insulin is present or not. During adipose conversion, T3 increased the development of enzyme activity and after a longer lag period, the accumulation of the synthetase. Our results suggest that the stimulating effect of T3 upon synthetase activity could involve as a first step the activation of preexisting inactive synthetase molecules and as a second one an increased accumulation of activable synthetase. After longer culture periods, inactive radioimmunoassayable synthetase accumulated.

Adipose Tissue↗
PubMed1983

Contourographic QT interval measurement.

A new presentation of ECG tracings is presented (contourography) which is suitable for ECG intervals measurements, particularly QT for prolonged periods of time. Possible applications of this method are looked for in the future.

Animals↗
PubMed1983

Comparative study of electrophysiological and Holter monitoring data in estimating sinoatrial function. Significance of intrinsic heart rate in disclosing autonomic sinus node dysfunction.

To study the diagnostic possibilities and mechanisms involved in sinus node dysfunction (SND), 26 patients with sick sinus syndrome were evaluated by basic electrophysiological tests before and after autonomic blockade, and by Holter monitoring. Based on intrinsic heart rate (IHR), two groups, a normal and a pathologic one, were separated. With Holter recordings, significant differences were manifested in minimal heart rate during sleeping and also in sinus cycles averaged for 24 h between the two groups. In patients with pathological IHR (n = 9) abnormal intrinsic rhythmicity were verified by electrophysiological means, while we found positive ECGs referring to sinoatrial dysfunction during the first 24 h of rhythm recording. The group of normal IHR (n = 17) covers patients with intrinsic SND (intrinsic SA block, 3/17 patients) and patients (14/17) where the electrophysiologic properties of the pacemaker cells were normal: normal intrinsic recovery time, gradual return to the stable intrinsic sinus cycle length in the postpacing secondary cycles, biphasic postextrasystolic patterns with a well-estimated intrinsic sinoatrial conduction time. Repeated Holter recording (total 26 X 24 h) revealed severe bradycardia (2 cases), SA block (4 cases), SA arrest (2 cases), tachybradyarrhythmia (1 case). Electrophysiological studies have a low diagnostic value in autonomic SND; repeated rhythm monitoring is obviously the best complementary method for appreciating the role and significance of autonomic tone in sick sinus syndrome.

Adult↗
PubMed1983

[Mechanism of action of thyroid hormones at the cellular level].

Thyroid hormones exert pleiotropic effects at the cell level and several theories to define the initial site of action have been proposed. First mitochondria, nuclei or plasma membrane were considered as the main regulatory step. More recently, evidence of T3 and/or T4 binding sites present in different cellular compartments suggests the existence of more than one initial site of action. Binding sites from cytosol or plasma membrane and endoplasmic reticulum seem to participate either in the storage of thyroid hormones, or in their intracellular transport and metabolism. Mitochondrial and certain plasma membrane binding sites could be responsible for rapid effects of thyroid hormones at their level. Nuclear T3 binding sites located in the chromatin are considered as a true hormone receptor and are more documented in a structural and functional point of view. They may mediate thyroid hormone effects on the regulation of DNA transcription and the synthesis of active proteins. Their mechanism of action is nevertheless not well defined.

Animals↗
PubMed1983

[Resistant ventricular tachycardia caused by right ventricular dysplasia. A case of surgical recovery reported 6 years after intervention].

A 52 year old patient with no previous medical history had an attack of ventricular tachycardia, the configuration of which showed left sided delay. Electrical reduction was followed by multiple recurrences. There were ST-T wave changes over the right precordium on the basal ECG. The hydro-electrolytic equilibrium was normal. Coronary angiography and selective left ventricular cineangiography were also normal. Right angiocardiography showed an aneurysmal deformation of the pulmonary infundibulum. The recurrence of attacks over a two year period led to several hospital admissions, demonstrating the failure of antiarrhytmic therapy. The attacks became so frequent in the last three months that surgery was undertaken. Epicardial mapping showed delayed potentials over the pulmonary infundibulum and surgery consisted in resection of the abnormal infundibular zone. The macro- and microscopic pathological findings were of wall thinning and muscular degeneration with fibrosis and fatty infiltration. The authors discuss the relationship between right ventricular dysplasia and a localised form of Uhl's anomaly. Six years after surgery the patient has had no recurrence of the arrhythmia or shown signs of cardiac failure in the absence of any drug therapy.

Cardiomyopathies↗
PubMed1983

[Duration of electric systole in the acute phase of myocardial infarct. Methodology, natural history, semiological value, therapeutic consequences].

Extension of the duration of electric systol in the acute phase of coronary thrombosis can be analysed in satisfying conditions whatever the physiological frequencies by the measurement (formula; see text) represents the average QT measurement of three non-consecutive complexes in five derivations (DI, DIII, aVF, VI and V6). This extension is of prognostic value when the QTc is greater than 44 c/s. Out of 1 255 acute phase thrombosis patients, 18 Out of 20 cases of ventricular fibrillation revealed a QTc greater than 44 c/s in the 24 hours preceding sudden death. Therapeutic intervention with anti-andrenergic drugs such as bretylium tosylate or beta-blocking agents appears to reduce the QTc of these patients and thus prevent sudden death.

Acute Disease↗
PubMed1983

[Postextrasystolic sinus responses after autonomic blockade in patients with sinus node dysfunction].

The interpretation and significance of postextrasystolic responses obtained in human electrophysiological examinations of patients with sinus node dysfunction has long been a matter of controversy. We carried out programmed atrial stimulation by the method of Strauss et al. in 54 patients with sinoatrial disorder, before and after pharmacologic autonomic blockade (with propranolol 0.2 mg/Kg and atropine sulfate 0.04 mg/Kg intravenously). There were two responses, as follows: computable sinoatrial conduction times and chaotic patterns. Patients were divided into groups on the basis of their intrinsic heart rate (IHR). If the total estimated sinoatrial conduction time over greater than or equal to 200 msec and greater than or equal to 147 msec after autonomic blockade and chaotic pattern were considered to be pathologic, so the ratio of abnormal parameters decreased from 73 to 44% in patients of normal IHR, and increased from 70 to 90% in patients of abnormal IHR. The latter 90% was mostly to the expense of the incalculable chaotic patterns. Interpreting a postextrasystolic curve, the existence of reset zone refers to the functional integrity of the sinoatrial node, to the organisation and synchronism of sinus potentials, which depends on the balance of autonomic nervous system and on the intrinsic electrophysiological integrity of the pacemaker cells.

Adolescent↗
PubMed1983

Autonomic sinus node dysfunction documented by Holter monitoring studies in 21 patients.

Holter recordings were carried out in 21 patients with presupposed sinus node dysfunction (SND). All the patients were evaluated also by complex electrophysiological examinations (overdrive and premature atrial stimulation) before and after pharmacologic autonomic blockade (AB) with propranolol 0.2 mg/kg and atropine 0.04 mg/kg body weight intravenously. Groups of normal and abnormal intrinsic heart rate (IHR) were compared. In patients with normal IHR (n = 13) the prolonged recovery time (5/13), postpacing SA-block (1/13) and chaotic postextrasystolic patterns (4/13) ceased after AB. Intrinsic recovery time became normal with a gradual return to the stable sinus cycle length, and we obtained normal biphasic postextrasystolic intrinsic return responses. In all cases of pathological IHR (n = 8), abnormal intrinsic rhythmicity was verified by electrophysiological means. Holter monitoring revealed significant differences (P less than 0.001) between the minimal HR during sleeping and also in the HR averaged for 24 h between the two groups. In patients with abnormal IHR, the 24 h rhythm recording revealed positive ECG data for SND. In patients with normal intrinsic electrophysiological properties, Holter monitoring revealed severe sinus bradycardia (1 case), SA-arrest (1 case), SA-block (1 case), tachy-brady syndrome (1 case), and atrial fibrillation with AV-block (1 case). For appreciating the role and significance of the autonomic neuro-vegetative tone in SND, continuous rhythm monitoring is necessary.

Adult↗
PubMed1982

[Implantation of a pacemaker and superior vena cava anomalies: value of peroperative angiocardiography].

Rare abnormalities of systemic venous return may be encountered during the implantation of endocardiac pacemakers such as persistent left superior vena cava. Our patient, a 66 year old female, had, primary cardiomyopathy with sinus node dysfunction, left bundle branch block and a cardiothoracic ratio of 0,70. After left subclavian venous puncture the catheter seemed to advance down the left border of the cardiac shadow and a false route was suggested? Angiocardiography was performed immediately and showed a double superior caval system and allowed identification of the right ventricular apex. The electrode was positioned via a left SVC, coronary sinus, right atrium, right ventricle trajectory. Control angiocardiography was performed 1 year later and showed both the left SVC and coronary sinus to be still patent. The follow-up period is now 20 months. There have been 13 other reports of implantation using the left SVC; they include 4 short term failures, one late failure at 23 months, and one fatality after 2 months due to massive thrombosis of the coronary sinus. Seven good results were confirmed with follow-up of 3 to 16 months. The use of "tined" ventricular electrodes reduces the risk of secondary electrode displacement.

Aged↗
PubMed1982

Holter monitoring in the complex analysis of sinus node dysfunction.

To study the diagnostic possibility and the mechanisms involved in sinus node dysfunction, 23 patients with sick sinus syndrome were evaluated by the basic electrophysiological method (recovery times, secondary postpacing phases, sinoatrial conduction times) before and after pharmacologic autonomic blockade with i.v. propranolol 0.2 mg/kg and atropine 0.04 mg/kg, and by continuous rhythm monitoring. Patient groups of normal (I) and pathological (II) intrinsic heart rate (IHR) were compared. In group I (no. 15) prolonged recovery time (2/15), postpacing sinoatrial-block (1/15) and chaotic postextrasystolic patterns (5/15) ceased after autonomic blockade; we obtained normal intrinsic recovery time, gradual return to the stable intrinsic sinus cycle length in the secondary phase, and a normal intrinsic sinoatrial conduction time. In group II (no. 8) during the control study only 50% of patients had pathological electrophysiological parameters before, and 100% after the drug test (no gradual postpacing return to the intrinsic heart rate, abnormal recovery times, abnormal sinoatrial conduction times or chaotic postextrasystolic patterns). Holter monitoring revealed significant differences between the minimal heart rate during sleeping (group I: 48 +/- 10 bpm, mean +/- SD group II: 32 +/- 4 bpm, probability less than 0.001) as well as in the average sinus cycle length for 24 hours (group I: 848 +/- 88 ms, group II: 1254 +/- 136 ms, P less than 0.001) with a very characteristic histogram. In the patients with pharmacologically and electrophysiologically documented abnormal intrinsic rhythmicity (group II), the first 24 hour Holter monitoring revealed positive ECGs for sinus node dysfunction. In patients with normal intrinsic electrophysiological sinus node properties (group I) repeated continuous rhythm recordings revealed severe sinus bradycardia (1 patient), sinoatrial-block (1 patient), tachybrady syndrome (1 patient) and sinus-arrest (2 patients, up to 29 120 ms in waking period). These findings suggest that 1) IHR is the best and simplest diagnostic method of intrinsic sinus node dysfunction (in patients of abnormal low IHR we found positive electrophysiological and Holter parameters), and 2) in autonomic sinus node dysfunction electrophysiological parameters are essentially negative showing normal intrinsic sinus node function; in these patients systematically repeated Holter monitoring is the most valuable diagnostic method.

Adult↗
PubMed1982

Electrophysiological classification of normal and pathological sinus node function.

The sympathetic and parasympathetic neurological cardiac effects were blocked with atropine and propranolol. The intrinsic heart rate (IHR) was determined and rapid atrial pacing (RAP) was carried out before and after administration of the drugs. The primary and secondary postpacing parameters were examined in both circumstances. Normal (n = 31) and pathological (n = 20) cases were differentiated on the basis of the IHR. In the secondary phase (PPC 2-10) after autonomic blockade returned to the basic frequency was of exponential character in the great majority of normal IHR cases. Anomalies may appear in both the primary and secondary phases. They are of different types: one of them concerns the recovery time; another electrophysiological anomaly occurs when there is no return to the predrive normal cycle length after pharmacological neurotomy. In the secondary phase there may appear sinoauricular blocks. They may depend on or appear independently of the effect of the vegetative nervous system. The new test allows a physiopathological classification of normal and pathological sinus node function.

Adult↗