Search PubMed⌕ Search

Biomedical subjects

J Torresani

Publications and source records attributed to J Torresani.

At least 109 records · Page 6Linked to original sources
PubMed1977

Haemodynamic and baroreceptor responses to beta-adrenoceptor blocking agents in rabbits with cardiopulmonary bypass.

Blood pressure and peripheral resistance were reduced, baroreceptor activity was enhanced after i.v. infusion of beta-adrenoceptor blocking agents in rabbits with intact circulation or with total cardiopulmonary bypass. The latter preparation allowed cardiac effects of the drugs to be excluded. In rabbits with an intact circulation, post-ganglionic sympathetic activity was reduced. These results suggest a direct vascular action of the drugs. The increased baroreceptor firing is not a cardiac-mediated effect and may partly induce the observed reduction in sympathetic activity.

Adrenergic beta-Antagonists↗
PubMed1977

[Reduction of efferent renal nerve activity by propranolol in rabbits].

During intravenous infusion of propranolol (0.3--0.8 mg/kg) in the Rabbit, systolic arterial pressure is decreased (-6.5 +/- 4.2 mmHg) and electrical activity recorded from central end of the renal nerve is reduced significantly (-8.7 +/- 14.-%) with regard to the activity obtained, at the same pressure levels, by hemorrhage (+7.9 +/- 6.4%; p less than 0.25) or by intravenous infusion of the peripheral vasodilator sodium nitroprusside (+14.1 +/- 9.9%; p less than 0.01).

Animals↗
PubMed1977

[Use of sodium nitroprusside in cardiology].

Sodium nitroprusside (SNP) is rarely used in cardiology. It is reserved traditionally for severe episodes of arterial hypertension. Certain states of refractory heart failure represent new indications for use, which implies a double haemodynamic monitoring system: continuous control of systemic blood pressure by intra-arterial catheterization; control of pulmonary pressure and repeated measurements of cardiac output. Prolonged treatment requires continuous biological monitoring of toxicity and careful control of kidney function. As a moderator of blood pressure, SNP is remarkably effective. The hypotensive effect is immediate, readily reversible and generally tachyphylaxis is not observed. The effect of SNP on cardiac work is one of double load reduction: mainly a reduction in afterload or pressure and systemic resistance and a reduction in preload or pressure of ventricular filling. In this respect, SNP can be used effectively for severe cases of heart failure intractable to traditional cardio-stimulatory and diuretic treatments and stemming from diverse causes: acute stage of myocardial infarction, ventricular dilatation, mitral papillary syndrome, heart failure, either subacute or chronic, of various causes. As a rule, the immediate results are positive. Taking the patient off the drug can be difficult and may cause a return to the previous haemodynamic situation.

Adult↗
PubMed1977

[Hemodynamic profile of acute myocardial infarction as a function of electrocardiographic localization].

The haemodynamic profiles of 147 cases of myocardial infarction investigated within 30 hours of the clinical onset were studies in relation to the topography of the necrosis on the ECG: there were 36 inferior (I), 29 postero-inferior (PI), 22 antero-septal (AS), 38 antero-lateral (AL), 15 deep septal (DS), and 7 strictly posterior or lateral (PL). Simultaneous recordings of the diastolic pulmonary arterial pressures and the left ventricular diastolic pressures (pre-and post-a) have shown different degrees of correlation with the topographical site. The correlation found in AS, AL and I necrosis are clearer with respect to the pre-a. The PI necroses show no correlation. Graphs of left ventricular function as well as an analysis of the various other parameters show that the DS, the AL, and to a lesser extent the PI are associated with the grossest depression of left ventricular function. A study of the amplitude of the "a" wave also shows that the effect of infacts of the free wall of the left ventricule on the compliance is greater. A study of right ventricular function as well as the correlations between the pulmonary and right atrial pressures confirms the presence of right ventricular disfunction in DS and PI necroses. Impaired left ventricular function, impaired right ventricular function, and disorders of compliance seem to be the determining factors in changing the haemodynamics in the various ECG sites of infarction.

Acute Disease↗
PubMed1977

[Electrocardiagraphic changes of Prinzmetal's angina type in the acute phase of myocardial infarct].

The authors have studied the frequency and severity of anginal attacks of the Prinzmetal type coming on during the acute phase of a myocardial infarction in 13 patients. They have occurred in 5.50% of cases (anginal attacks of all types occurring in 18.34% of cases). The severity of these attacks is shown by their clinical features: the multiplicity of the attacks, the high incidence of arrhythmias, the difficulties encountered with medical treatment. This also confirmed by the enzyme studies: when the curve of myocardial creatinine kinase release is drawn, there is seen to be an extension of the lesion in 2/3 cases, whereas the electrocardiograph does not show this up.

Acute Disease↗
PubMed1976

Cardiac output measurement by thermodilution: methodologic problems.

In clinical practice, thermodilution technique for cardiac output measurement is generally applied to the right heart (injection of a saline cold bolus in the right atrium, temperature measurement downstream in the pulmonary artery). This technique is well adapted to repetitive measurements using a single catheter. However, its validity is dependent on several methodologic requirements: quantitation of the indicator, control of the catheter's dead-space effect, conservation and mixing of the cold bolus, accurate measurement of small thermal gradients. Calculations from the thermal dilution curve must be adapted to possible baseline shifts. All these different methodologic aspects are studied. Several solutions (heat exchanger, automatic injection, calculation method) are proposed. Comparison between an automatic thermodilution device and dye dilution has been performed successfully.

Cardiac Catheterization↗
PubMed1976

Factors influencing triiodothyronine binding properties of liver nuclear receptors.

Triiodothyronine (T3) may bind directly to receptors present in liver cell nuclei, or may be transported into nuclei by receptor protein(s) present in the cytosol. To evaluate these possibilities, T3 binding was studied in vitro using liver cell nuclei isolated from rats exposed in vivo to very low (H), normal (N),or high levels of T3 (H + T3), and using nuclei incubated in vitro with added cytosol proteins. Ka for T3 was 0.075 +/- 0.05 x 10(10) M-1 in N, 0.1 + 0.04 in H, and 0.094 + 0.04 in H + T3, and pg T3 bound/100 mug DNA were 47 +/- 17, 31 +/- 14, and 29 +/- 8 in the three groups. The data indicate no difference in binding capacity between the groups related to prior in vivo exposure to T3, and that T3 may bind directly to empty nuclear receptor sites. Rat liver cytosol proteins added to the in vitro incubation medium always depressed T3 uptake by nuclei. Bovine serum albumin had a similar effect. Large amounts of rat serum proteins depressed uptake, but low levels augmented T3 binding through an unknown mechanism. It is probable that free T3 in serum is in equilibrium with free T3 in the cytosol and nucleus, and binds directly to nuclear receptor proteins without mediation by a cytosol receptor protein.

Animals↗
PubMed1976

[Approach to the prognosis of myocardial infarct from the initial hemodynamic examination].

Hemodynamic investigations (right and left heart catheterization, cardiac output measurement) were performed in 132 patients with acute myocardial infarction. Retrospective study of the first 100 patients allowed determination of prognostic indices. A new statistical method is proposed which was used prospectively in the 32 following patients and resulted in an error of prediction of about 3 per cent. The establishment of prognosis from hemodynamic data is a necessary condition prior to new therapeutic approaches of cardiac failure in acute myocardial infarction.

Adult↗
PubMed1975

Defective thyroglobulin export as a cause of congenital goitre.

The thyroids of two brothers aged 13 and 15 with congenital goitre, butanolinsoluble iodine in blood and which had pronounced decrease of immunoreactive thyroglobulin content in the thyroid were studied. Two types of thyroglobulin were identified. The first amounted to only about 200-300 mug/g wet tissue and was fully immunoreactive with anti normal human thyroglobulin antiserum (iTG-G). It was purified by affinity chromatography. The other was mainly associated with intracytoplasmic membranes, amounted to about 8 mg/g wet tissue and was only partially immunoreactive (piTG-G). Both had abnormal amino acid compositions but only iTG-G showed a decreased carbohydrate content. Surprisingly, piTG-G showed a normal iodination level (0-5%) and a normal iodoamino acid composition. Immunochemical studies performed on slices or cell-free fractions incubated in the presence of labelled amino acids and/or monosaccharides showed that: (1) thyroglobulin peptide chains were being synthesized and almost normally discharged into the cisternae of the rough endoplasmic reticulum; (2) incorporation of sugars into iTG-G was decreased; (3) sialyl- and galactosyltransferase activities were normal and the enzymes normally located, and (4) albumin which is present in the thyroid as the iodinated protein was probably not synthesized by the goitrous tissues. Two major abnormalities were detected by light and electron microscopy: absence or pronounced scarcity of colloid in the follicular lumina and overdistended endoplasmic reticulum cisternae. These observations are compatible with a defect in TG transport from the cell into the lumen as the cause of the goitre. Whether defective thyroglobulin export is basically related to abnormality of the protein structure or to another cause is discussed.

Adolescent↗
PubMed1975

Triiodothyronine binding to isolated liver cell nuclei.

Nuclei of euthyroid rat liver have been prepared from homogenates by sedimentation through 2.3M sucrose with or without a 0.25% Triton wash. Triiodothyronine is accumulated by these nuclei during incubation in vitro in solutions containing 0.32M sucrose, 1mM MgCl2 and 0.02M Tris-Cl buffer at pH 7.4 or 7.85. Specific T3 binding sites occupied at 10-1,000 pM T3 are saturated by excess unlabeled T3 (0.15 muM). Specific T3 binding at 20 C is maximal at 203 hr nad is proportional to amount of nuclei. Calcium ion enhances nuclear integrity by reduces T3 accumulation. EDTA and phosphate ion cause nuclear damage but increase T3 accumulation. Binding is unaffected by inhibition of energy dependent reactions or of RNA synthesis. It is markedly increased under certain conditions by addition of dithiothreitol (DDT). Binding does not require mediation of a cytosol protein. T3 binding is not prevented by RNAse or DNAse, but is obliterated by pronase. Te binds to a nuclear iodothyronine binding protein (NTBP) to form an NTBP-T3 complex similar to that form-d after in vivo administration of the hormone. The complex can be extracted from the nuclei by 0.4M KC-. T3 present in the NTBP-T3 complex resists accumulation by anion exchange resin at 0-2C, but is bound by resin after 20 min at 37C or after addition of 0.1 mM p-hydroxymercuribenzoate. At pH 7.85 and with 5 mM DTT, the apparent Ka for isolated nuclei is 0.2 times 10-10M-1 and the capacity is 508 pg T3/g wet tissue or 53 times 10-15 moles T3/100 mug DNA. The data may not represent total capacity, but rather the amount of T3 dissociated during the period of incubation so that NTBP-T3 can be exchanged with labeled T3. Among analogues tested, triiodothyroacetic acid appears to bind with four times the affinity of L-TX, D-T3 binds with equal affinity, and L-T4 with one-fourth the affinity of T3.

Animals↗
PubMed1975

Triiodothyronine binding to liver nuclear solubilized proteins in vitro.

Nuclear proteins extracted from purified nuclei with 0.4M KCl at pH 7.4 OR 8.5 are able to bind L-triiodothyronine (T3) giving rise to nuclear thyroid hormone binding protein-T3 (NTBP-T3) complexes. Binding is maximum in 3 h at 20 C. It is thermolabile even at 36 C, inhibited by p-hydroxymercuribenzoate and markedly enhanced by dithiothreitol. Optimum pH is between 7.8 and 8.5. Divalent cations are not necessary. The NTBP-T3 complex exhibits similar anodal electrophoretic migration in polyacrylamide gel at pH 8.5, whether formed in vivo or in vitro. Scatchard plots obtained with various amounts of T3 from 0.15 nM TO 0.15 MUM and either unlabeled nuclear proteins or in vivo formed NTBP-[125I]-T3 complexes, give apparent association constants K-a of 0.2 X 10-10 M minus at pH 7.4 and 0.8 X 10-10 M minus 1 at pH 8.5. Capacity is about 0.5 pmol T3 per mg protein or 800 pg/g liver. The presence of dithiothreitol markedly enhances the Ka. The nuclear binding sites are not highly specific for L-T3 since they are able to bind D-T3 with almost equal affinity and triiodothyroacetic acid with a higher affinity. L-thyroxine (T4) can also displace L-T3 but with about 10-fold lesser effectiveness. Nuclear binding proteins of low capacity and high affinity have been demonstrated in vitro. The NTBP-T3 complexes formed in vivo, with whole nuclei, or in vitro are indistinguishable.

Animals↗
PubMed1975

[Total cardiopulmonary bypass in rabbits. Techniques and the effect of pulsatile perfusion pressure on hemodynamic parameters].

Fifty-two total cardiopulmonary bypasses (CA) have been performed in rabbits in order to obtain a stable preparation. The present paper deals with techniques and haemodynamic results. 1. Two kinds of priming solution have been used. Best results were obtained by using Ringer-lactate-gelatin (65 ml) and T.H.A.M. (5 ml). 2. Pulsatile arterial perfusion was performed either at uniform frequency (series A:10 experiments) or in accordance with the arterial mechanical resonance frequency of each animal (series B: experiments). The later setting resulted in better levels of maximal arterial pressure throughout the experiments (p less than 0,001). 3. The perfusion pressure flows (integrated at minute intervals), and total peripheral resistances, were studied on two groups of 4 animals each, A' and B' forming a part of A and B respectively. The flows were higher in B' after 5 min of CA (p less than 0,001), and after 40 min of CA (p less than 0,025); the flow increased during the experiment in group A' but remained in a steady state in group B'. The differences in total peripheral resistances were not statistically significant after 5 min of CA, but were smaller in A' after 40 min of CA (p less than or equal to 0,025); the difference in the variation of total peripheral resistances was statistically significant (p less than 0,025).

Animals↗