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Biomedical subjects

J Torresani

Publications and source records attributed to J Torresani.

At least 91 records · Page 5Linked to original sources
PubMed1981

In vitro binding of triiodothyronine to rat liver mitochondria.

Saturable high affinity T3 binding sites were detected in a mitochondrial fraction enriched in internal membranes and partly solubilized by Triton X-100. Specific T3 binding to the solubilized sites, only detected at low T3 concentrations, was optimal at pH 8.0 and not dependent upon the presence of divalent cations or reducing agents; it was destroyed by heat and proteolytic enzymes. The solubilized T3 binding sites were distributed, after Sephadex G-200 gel filtration, between two peaks of similar affinity for T3 (Ka congruent to 5 x 10(10)l/mol) and similar binding characteristics. T3 was bound with a high stereospecificity, while some analogues of biological importance (L-T4; 3,5,3'-triiodothyroacetic acid; 3,3';-diiodo-L-thyronine) competed with L-T3 in the same range of low concentrations. This suggests that the high affinity mitochondrial T3 binding sites could be of biological relevance in the mitochondrial metabolism.

Animals↗
PubMed1981

Relationship of pulmonary diastolic and pulmonary wedge pressures to left ventricular diastolic pressures: role of acute myocardial infarction localization.

Right and left hemodynamics have been simultaneously studied in 127 patients with acute myocardial infarction with respect to electrocardiographic localization. Hemodynamic profiles of the different localizations suggest a high incidence of right ventricular dysfunction in infero-posterior infarcts. The comparison with the other localizations suggests that such a right ventricular dysfunction is likely to be responsible for an additional underestimation of left ventricular end-diastolic pressure when estimated by pulmonary diastolic pressure.

Adult↗
PubMed1981

Triiodothyronine and adipose conversion of OB17 preadipocytes : binding to high affinity sites and effects on fatty acid synthetizing and esterifying enzymes.

Cells of a preadipocyte clonal line (ob 17) isolated from epididymal fat pad of ob/ob mouse possess high-affinity binding sites for triiodothyronine. A single class of sites was found on growing and early confluent cells (KD 0.14 +/- 0.025 nM ; 5,000 +/- 600 sites per cell). A two-fold increase in the number if T3 binding sites occurs during adipose conversion, with no significant change in KD values. The order of potency of structural analogs to compete with 125I-T3 is in favor of nuclear binding sites. A correlation was obtained 3 between this order of potency and the ability of the analogs, included on a long-term basis to confluent cells, to increase 14 C-acetate incorporation into lipids, suggesting an enhancement of de novo fatty acid synthesis, This hypothesis was supported by increased activity levels of fatty acid synthetase after chronic exposure to 1.5 nM triiodothyronine. Under these conditions activity levels of acid:CoA ligase and glycerol-3-phosphate dehydrogenase were also increased significantly. Inclusion of bromodeoxyuridine as a differentiation-blocking agent in the culture medium of growing cells decreases drastically the T3 effects, favoring the role of the latter hormone as amplifier of specific phenotypes expressed during adipose conversion. These results show that ob17 cell line should be an useful tool to study the role of thyroid hormones in the regulation of fatty acid synthesis and esterification in adipose cells.

Acetates↗
PubMed1981

[Acute phase of ventricular fibrillation in myocardial infarct. Importance of studying electrical systole by determining the QTc].

Recent reports have drawn attention to the association between long QT intervals and sudden death in myocardial infarction and certain congenital syndromes. This study was undertaken to determine the relationship between lengthening of the QT interval and primary ventricular fibrillation in acute myocardial infarction. Thirteen cases were chosen out of a total of 21 cases of primary ventricular fibrillation (5.09% of 412 cases of myocardial infarction hospitalised during this period). Ten other cases of myocardial infarction with the same features apart from the arrhythmia were used as controls. Three series of electrocardiogrammes recorded under the same technical and chronological conditions (2 before and 1 after ventricular fibrillation) were analysed. The average QT interval was corrected for heart rate (RR) with Bazett's formula. The average QTc in acute myocardial infarction was longer than the theoretical QTc (p less than 0.05). The graph showing this increase reached a peak at the 48th hour. The average QTc in patients with primary ventricular fibrillation was longer than in the control patients (p less than 0.05) and significantly longer than the theoretical value (p less than 0.001). The average QTc in survivors of ventricular fibrillation was not significantly longer than that of the control group but was longer than the theoretical value (p less than 0.01). These results justify the strict surveillance of the length of electrical systole in the first hours of the acute phase of myocardial infarction. In this series, values greater than 440 ms were associated with a high risk of ventricular fibrillation in the first week after myocardial infarction.

Acute Disease↗
PubMed1980

Prolonged electrical systole in acute myocardial infarction.

Electrical systole duration has been studied in two groups of 23 patients (39 M and 7 F) admitted in the coronary care units of two different hospitals for documented acute myocardial infarction (AMI). The mean QT interval duration corrected for heart rate (QTc) was obtained from three measurements of non consecutive complexes in five different leads and compared to the ideal electrical systole duration of a normal population with the same cardiac cycle length. During the evolution of AMI, QT interval increased in both groups of patients (11.5% and 14.8% respectively) and was prolonged (17.6% and 21.5% respectively) at the 48th hour. Prolongation of electrical systole can be best measured using the ratio: QTc (according to Bazett)/normal QT (according to Ashman).

Electrocardiography↗
PubMed1980

[Subclavian route placement of electrodes for permanent stimulation].

The subclavian vein gives a rapid, direct approach to the right heart cavities. The pacing catheter was introduced via the subclavian vein in a series of 187 patients. A no. 9 Desilets and Hoffman percutaneous catheter introducer may be used with most types of pacing catheter, including bipolar models. Complications were rare : one case of pneumothorax was observed. The subclavian vein approach simplified the operative procedure of implantation and offers a useful alternative in difficult cases of reimplantation.

Female↗
PubMed1979

[Presentation of continuous electrocardiograms in compressed form. Preliminary note].

The conventional electrocardiogramme is poorly suited to the study of continuous electrocardiographical recordings. The rapid interpretation of recordings obtained by the Holter method is not compatible with the preservation of an analogous record of the whole period under study. The study of continuous electrocardiogrammes by computer uses only part of the data recorded. The technique of compression based on the principle of Contourography is a method of preserving continuous electrocardiographical records in their analogical form. This recording is a useful addition to the Holter method.

Electrocardiography↗
PubMed1978

Properties of solubilized nuclear triiodothyronine binding proteins.

Rat liver nuclear proteins bind 3,5,3'-triiodo-L-thyronine (T3) to essentially one class of sites (Ka approximately 1 X 10(10) M-1). Gel filtration and sucrose gradient centrifugation studies show a main T3 binding component with a Stokes radius of 33 A and a sedimentation coefficient of 3.5S, and variable amounts of high molecular weight binding components, most of them being reversible aggregates of the main component formed during storage. But the uniqueness of the nuclean T3 binding proteins (NTBP) cannot be ascertained from polyacrylamide gel electrophoresis data. During storage in the absence of reducing agents, NTBP aggregate and rapidly lose their ability to bind T3; T3--NTBP complexes also aggregate and progressively dissociate. This can be reversed by dithiothreitol. Bound T3 could temporarily stabilize the binding site but cannot protect NTBP against general conformational changes which follow the oxidation of their essential --SH group(s). NTBP are DNA binding proteins with probably a relative independence of their DNA and T3 binding sites: they bind T3 to the same class of high affinity sites whether complexed or not with DNA; bound T3 is not a prerequisite for DNA binding.

Animals↗
PubMed1978

[Application of echocardiography to the diagnosis of tricuspid valve diseases. Apropos of 103 cases].

In a series of 103 consecutive surgical patients, the normal and pathological echocardiographic appearances of the tricuspid valve were analysed and compared with the anatomical findings. It was possible to define the nature of the lesions by echocardiography, which was superior to angiography in this field. The right ventricular index (right ventricular dimension body surface area) correlated well with the mean pulmonary artery pressure (r = 0.75; p less than 0.001). The index may be useful in the long term follow-up of post-operative patients.

Adolescent↗