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Biomedical subjects

J Torresani

Publications and source records attributed to J Torresani.

At least 55 records · Page 3Linked to original sources
PubMed1986

Triiodothyronine (T3)-induced down-regulation of the nuclear T3 receptor in mouse preadipocyte cell lines.

As previously reported, preadipocytes cloned from the epididymal fat of lean or genetically obese mice (HGFu and ob 17, respectively) contain the nuclear T3 receptor. The number of receptor sites was similar in confluent cells of both lines and approximately doubled during adipocyte differentiation. T3 added to the culture medium increased triacylglycerol synthesis. T3 also increased fatty acid synthase specific activity, relative synthesis rate, and relative mRNA content (1.5- to 2.5-fold). Optimal responses were obtained at 1.5 nM. This study shows that under the same culture conditions in both cell lines, 1.5 nM T3 decreased the receptor concentration with no significant change in the affinity for T3. The receptor depletion was time dependent, rapid, stable in the presence of T3, and reversible in less than 24 h after its withdrawal. Receptor depletion was also dependent on T3 concentration and close to maximum at 1.5 nM T3 [45.1 +/- 2.7% (+/- SE) of the data values without T3; n = 14]. A linear relationship was observed between receptor occupancy by T3 and receptor loss. T4 and triiodothyroacetic acid also decreased the T3 receptor content, as expected from their own affinity for the receptor. These last two observations suggest that the receptor reduction is related to its occupancy by T3. The reported results, also observed in several other cell types, indicate that down-regulation of the nuclear T3 receptor by thyroid hormones is probably a generalized event in T3 target cells at least in vitro. Interpretation of its significance in preadipocyte cell lines requires further studies of rapid nuclear events following T3 receptor occupancy.

Adipose Tissue↗
PubMed1986

[Angina accelerated under betablockers].

An observation of angina aggravated in a concomitant manner with the introduction of treatment with beta blockers is reported. The exacerbation of a vasospastic component with this treatment is evoked on clinical, electrical and coronarographic grounds.

Adrenergic beta-Antagonists↗
PubMed1986

[Nifedipine in the treatment of chronic cor pulmonale].

The effects of a single dose of nifedipine (20 mg sublingual) on the haemodynamics and parameters of tissue oxygenation were assessed by right heart catheterisation and oximetry of mixed arterial and venous blood in 24 patients with pulmonary hypertension secondary to severe chronic obstructive airways disease. The haemodynamic effects of 15 days' oral therapy (30 mg/day) were studied in 10 other patients. Significant improvement in right ventricular pump function (25 p. 100 increase in cardiac index. average reduction of 3 mmHg of right ventricular end diastolic pressure), and lowering of pulmonary hypertension (mean pulmonary artery pressures reduced by an average of 10 p. 100 and total pulmonary resistance by 25 p. 100) were observed after the single dose of nifedipine. This improvement was maintained after oral therapy for 15 days. The significant improvement of tissue oxygenation was reflected by an increase in oxygen transport (+ 24 p. 100), in the coefficient of delivered oxygen (+ 19 p. 100), in the oxygen partial pressure (+ 4 p. 100) and saturation (+ 3 p. 100) in the mixed venous blood. Arterial lactate concentrations fell by about 28 p. 100. In addition, a moderate fall in ppO2 and arterial saturation was observed due to a weak shunt effect which was more than compensated by the increase in cardiac output, and especially by the increase in the coefficient of relieved oxygen. These results show that nifedipine may be a valuable addition in the treatment of cor pulmonale secondary to chronic obstructive airways disease by improving right ventricular haemodynamics and pulmonary circulation and by increasing the quantity of oxygen delivered.

Adult↗
PubMed1985

Triiodothyronine nuclear receptor and the role of non-histone protein factors in in vitro triiodothyronine binding.

The rat liver triiodothyronine (T3) nuclear receptor rapidly looses, after a partial purification from the nuclear extract, its ability to bind T3. We previously reported that histones, in the presence of DNA, could protect against inactivation enhancing the T3 binding site concentration and maintaining the high affinity for T3. A nuclear fraction discarded during the receptor purification (fraction A) was also found able to restore T3 binding and was analyzed. As histones + DNA, fraction A stabilized the T3 binding site from irreversible inactivation during incubation with T3, increasing its concentration while keeping the same high affinity for T3. It was active even at relatively high receptor concentration, appeared slightly more active than histones (+ DNA) in the same protein concentration range (up to 50-fold increment of T3 binding at the optimal concentration of 25 micrograms/ml) and was unaffected or slightly inhibited by DNA. Other proteins (ovalbumin, soybean trypsin inhibitor, RNAase) and rat liver cytosol were several times less effective, suggesting a major role of some nuclear constituents. The active factors in fraction A essentially belong to non-histone nuclear proteins. Fraction A was found heterogeneous regarding the molecular size and pHi of the active factors, the existence of subfractions more active on a protein concentration basis being suggested but not yet clearly evidenced. Efficient in vitro T3 binding to the isolated T3 nuclear receptor thus depends on the presence of several different nuclear constituents, histones + DNA or some non-histone proteins. Whether interactions with these constituents could modulate T3 binding within the nucleus remains to be elucidated.

Animals↗
PubMed1985

[Contribution of complementary examinations in the diagnosis and treatment of emboligenic cardiopathies. Retrospective study apropos of 46 cases].

The aim of this prospective study was to assess the value of complementary investigations in the diagnosis and follow-up of embolic heart disease. Forty-six patients having presented a systemic embolism cardiac origin underwent a standard work up which included clinical examination, ECG, chest X-ray and 2D echocardiography. Other investigations were carried out in some patients: CT cardiac scan (11 cases), gamma scintigraphy with Indium III labelled platelets (6 cases) and angiocardiography (12 cases). The diagnosis of an embolic cardiac lesion was made after the standard investigations in 82% of cases. The remaining 18% of cases hall had echocardiographic abnormalities and enable the diagnosis of clinically imapparent conditions: mitral valve prolapse, aneurysm of the interatrial septum, valvular calcification and cardiomyopathy. A potentially embolic mass was visualised in 18 patients; 6 valvular vegetations, 12 left atrial or ventricular thrombi. The other specialised radionuclide, angiographic and CT investigations only confirmed the echocardiographic diagnosis of intravavitary thrombosis. These results were confirmed surgically in 19% of cases. This study shows that complementary investigations especially echocardiography, allow diagnosis of latent embolic cardiac lesions, some of which may benefit from surgical treatment. In addition, potentially embolic intracardiac masses may be visualised, so confirming the origin of systemic emboli. When surgery is not indicated, echocardiography is a good method of following up the results of medical treatment in some of these masses.

Adolescent↗
PubMed1985

[Symptomatology of hydatid cyst of the heart. Study of a continuous series of 13 cases and value of x-ray computed tomography].

Thirteen consecutive cases of cardiac hydatic cyst were studied. The cysts were usually multiple, predominantly left ventricular. There were two cases of rupture of left ventricular cysts with systemic embolism, and three ruptures of right ventricular cysts causing pulmonary embolism. The average age of the patients was 31 years: 12 patients lived in regions where hydatid disease was endemic. Other localisations of hydatic disease were found in 7 cases. Two patients were completely asymptomatic. Three patients presented with a tumoral syndrome. The presentation was atypical simulating coronary artery disease in 2 cases, valvular heart disease in 2 cases, pericarditis in 2 cases and bronchopneumonia in 3 cases. The electrocardiogramme showed sinus rhythm in all cases and changes of subepicardial ischaemia in 8 cases and acute cor pulmonale in 3 cases. Chest X-ray showed a localised deformation of the cardiac silhouette in 5 cases and calcification in 4 cases. Direct angiocardiographic signs were present in 2 out of 8 cases; usually there was an indirect image of endocavitary filling defect. The tumour was demonstrated by 2D echocardiography in the three most recent cases. The value of CAT was assessed in the last 2 cases: it was absolutely diagnostic in 1 case of septal localisation. The results were poor in the second case due to the presence of mitral calcification. Twelve patients underwent surgery; there were 3 deaths due to rupture and 1 death before surgery. The clinical presentation of cardiac hydatid disease is very variable and the diagnosis is difficult.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1985

[An anesthetic technic in dogs for studying the arrhythmogenic effects of acute coronary occlusion].

Intramuscular injection of levomepromazine (0.5 mg/kg) 30 min before intravenous injection of 10 mg/kg pentobarbital sodium induces a good surgical anaesthesia in dogs artificially ventilated with 50% N2O and 50% O2 and given 0.01 mg/kg atropine and 0.1 mg/kg pancuronium intravenously before left thoracotomy. This protocol is suitable for the study of the arrhythmogenic effects of acute one-stage coronary artery ligation in anaesthetized dogs. In fact, minor interference with the autonomic nervous system appears to be involved since heart rate is maintained slow and mean aortic pressure is kept within normal limits, as pH, PaO2, anc PaCO2 during subsequent periods. Acute circumflex coronary arterio-venous pedicle ligation close to the left main trunk division resulted in this model in a high incidence of ventricular fibrillation (10 out of 15 dogs) early (7 +/- 4 min) after occlusion. Specific interventions aimed at reducing the incidence of early post-ischemic life-threatening ventricular arrhythmias might be tested in this model.

Anesthesia, General↗
PubMed1985

Two-week nifedipine treatment for pulmonary hypertension complicating chronic obstructive lung disease.

The effects of nifedipine on hemodynamics and blood gases were studied in 10 patients with pulmonary hypertension secondary to chronic obstructive lung disease. Two different sets of test data were recorded. The first set of readings was taken immediately before and during the initial hour after sublingual administration of 20 mg of nifedipine. The second set was taken after 2 weeks of therapy with 3 X 10 mg per day. After the acute sublingual dose, a significant decrease in pulmonary arterial pressure and pulmonary vascular resistance was recorded: 13% and 26% respectively. This decrease was accompanied by a 32% increase in cardiac output. Similar findings were recorded at the end of the 2-week therapy. Moreover, at this time, although blood gas tension had not been significantly altered, oxygen delivery was 35% higher. No adverse side effects were observed. This study suggests that nifedipine therapy can improve hemodynamics and tissue oxygenation in patients with pulmonary hypertension complicating chronic obstructive lung disease.

Administration, Oral↗
PubMed1984

The role of triiodothyronine in the regulation of synthesis rate and translatable mRNA level of fatty acid synthetase in a preadipocyte cell line.

Triiodothyronine (T3) effects on the activity, rate of synthesis and mRNA content of the key lipogenic enzyme, fatty acid synthetase, were studied in differentiating ob17 preadipocytes cloned from ob/ob mouse epididymal adipose tissue. During differentiation in the presence of insulin, a 6-10-fold increase in both fatty acid synthetase specific activity and synthesis rate were reproducibly observed and occurred concomitantly. The relative synthesis rate exhibited a progressive elevation from 0.5% at confluence to a maximum level of 2% in the presence of insulin. The rate of the enzyme degradation determined by pulse-chase experiments was similar in differentiating cells and insulin-untreated cells of the same age (t 1/2, 40-42 h). Furthermore, the increase in the enzyme synthesis rate was preceded by a progressively elevating amount of mRNA encoding for this protein as detected by translation in a reticulocyte lysate cell-free system. It is thus suggested that the increment in total and neosynthesized fatty acid synthetase in essentially due to an increased enzyme synthesis, reflecting an increased relative content of its specific mRNA. T3 included at a physiological concentration (1.5 nM) in the culture medium enhanced significantly both enzyme synthesis and its specific mRNA. The most important T3 effect was an acceleration of both processes, a stimulation of the mRNA level being detected as early as day 3 post-confluence and maximum at day 5 when the effect on the synthetase synthesis rate and activity began to be enhanced. This suggests that T3 would mainly affect fatty acid synthetase as a pretranslational level.

Adipose Tissue↗
PubMed1984

Bretylium tosylate in patients with acute myocardial infarction.

Experience with bretylium tosylate accumulated during a period of over 10 years, during which time greater than 1,500 patients with acute myocardial infarction were treated, is summarized. On the diagnosis of acute infarction, the agent was given by continuous intravenous drip at a rate of 10 mg/kg/24 hours for 5 to 7 days for prophylaxis of ventricular fibrillation. Bretylium administration prevented primary ventricular fibrillation in about 99% of these patients. No undesirable side effects were observed with this protocol, which lessens the initial sympathomimetic effect of the drug while allowing sufficient time for the adrenergic neuronal blocking effect to develop. The beneficial effects of the drug are believed to be due, in part, to a direct electrophysiologic effect on both normal and ischemic myocardium. This effect equalizes the duration of both the effective refractory periods and the ventricular action potentials, and it creates conditions capable of blocking reentrant pathways. Bretylium stabilizes the duration of electrical systole in patients with acute myocardial infarction. Hemodynamic studies during bretylium treatment further confirm the effectiveness of this drug and have prompted additional studies to evaluate its potential as an agent capable of decreasing impedance in acute myocardial infarction.

Animals↗
PubMed1984

Pacemaker syndrome with DDD pacing.

DDD pacing may be associated with certain problems similar to those of the pacemaker syndrome. In the absence of mechanical dysfunction, pacemaker-mediated tachycardias have occurred in the presence of VA conduction. The correction of this problem is found in more versatile programming capability. In addition, certain phenomena relating to intraatrial conduction times and the optimal AV delay are discussed.

Arrhythmias, Cardiac↗
PubMed1984

Nuclear triiodothyronine receptor in differentiating preadipocytes cloned from obese and lean mice.

The nuclear T3 receptor was characterized in two T3-responsive preadipocyte cell lines cloned from the epididymal fat pads of ob/ob adult mice (ob 17 cells) and their lean counterpart (HGFu cells). Isolated nuclei from confluent or differentiating cells bound [125I]T3 to one class of high affinity sites exhibiting kinetic properties, stereospecificity, and salt extractibility of the nuclear T3 receptor. The solubilized T3 binding sites behave like the hepatic nuclear T3 receptor considering physicochemical and DNA binding properties. At confluence, no significant difference could be detected in equilibrium apparent affinity constant (Ka) and maximum binding capacity (MBC) for T3 whether nuclei were prepared from cells originating from ob/ob mice [Ka: 1.7 +/- (SE) 0.5 X 10(10) M-1; MBC: 432 +/- 29 fmol/mg DNA] or from lean mice (Ka: 1.6 +/- 0.2 X 10(10) M-1; MBC: 487 +/- 39 fmol/mg DNA). MBC values were in the range found in several T3-responsive tissues. This suggests that the primary defect in ob/ob mice is probably not at the level of the nuclear T3 receptor. Furthermore, during differentiation into adipose cells in both cell series, and roughly paralleling the amplifying effect of T3 on several lipogenic enzymes in the course of their development, the nuclear T3 receptor concentration significantly increased, attaining about twice the initial values after completion of the differentiation without any significant change in the affinity for T3.

Adipose Tissue↗
PubMed1984

[Changes in the nuclear triiodothyronine receptor during the differentiation of preadipocytic cell lines of mice].

During the differentiation process of ob 17 preadipocytes in the presence of insulin, a progressive increase in the nuclear T3 receptor concentration per cell (1.5 to 3 fold) was observed. This increase was not found related to the addition of insulin to the culture medium and was concomitant to the expression of several phenotypes of the mature adipocyte. Triiodothyronine (T3) added to the culture medium of these cells increases the lipogenic pathway and several enzymes involved in fatty acid synthesis and esterification. After T3 addition at the same optimal physiologic concentration of 1.5 nM, the cellular concentration of its nuclear receptor was clearly reduced, without any significant alteration in the apparent affinity constant. A similar behavior was observed in 3T3-L1 preadipocytes. The molecular mechanism of action of the T3 nuclear receptor within the chromatin is not known. The biological relevance of its depletion by T3 itself remains to be determined.

Adipose Tissue↗
PubMed1984

[Effect of captopril on pulmonary arterial hypertension in congestive heart failure associated with chronic obstructive bronchopneumopathy].

Acute hemodynamic effects of oral 25 mg of the angiotensin converting enzyme inhibitor captopril were studied in 8 patients suffering from left ventricular failure and severe chronic obstructive lung disease (COLD) with pulmonary hypertension. In all the patients left ventricular failure resulted from a dilated cardiomyopathy. No significant change in right or left ventricular function and a decrease of 10% in arterial blood pressure and total systemic resistances were observed after administration of captopril. It is suggested that patients suffering from left ventricular failure and severe chronic obstructive lung disease will not benefit from administration of captopril.

Captopril↗