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Biomedical subjects

A Masoni

Publications and source records attributed to A Masoni.

At least 91 records · Page 5Linked to original sources
PubMed1977

Physiopathological and diagnostic hypotheses in peripheral block.

Delays and conduction blocks may occur in Purkinje fibers, junctions and muscular cells. Since such blocks may take place everywhere in the ventricles and not only in the free walls, we prefer to use the term peripheral instead of parietal block. The electrophysiologic problems connected with such blocks are discussed. The localization of the ventricle affected by the block is usually simple using VCG recording and is based on the orientation of terminal vectors. It is more difficult to recognize the ventricular walls affected by the block, the intraparietal localization and the source of the block: Purkinje fibers, junctions or muscular fibers. We maintain the concept that peripheral blocks alter not only the terminal phases of ventricular depolarization, but sometimes also the initial ones, in that the Purkinje-junction-muscular fibers system can be damaged in the septum with the major conduction pathways remaining intact. Several discrepancies found between the prescence of electric patterns of septal necrosis and autopsy data may be explained by peripheral blocks localized in the left septum.

Electrocardiography↗
PubMed1977

[The effects of tolamolol on excito-conduction in men (author's transl)].

The electrophysiologic effects of tolamolol (UK-6558-01), a new beta-adrenergic blocking agent, were studied using the endocavitarian electrocardiography and the extrastimulus method. The drug was infused intravenously in the dose of 20 mg (0,23-0,36 mg per kilogram). Tolamolol resulted in: -- prolongation of sinus cycle length in 17 patients (P less than 0.001); -- prolongation of correct sinus node recovery time in 16 patients (P less than 0.001); -- there was no significant modification in intra-atrial conduction (P less than 0.3), while atrail effective refractory period was slightly lengthened (P less than 0.03); -- in A-V node conduction was prolonged in 17 patients (P less than 0.001) and the effective functional refractory periods were prolonged in all patients (P less than 0.001); -- a A-V block of 2 degrees grade appears in 17 patients at a more prolonged cycle length (P less than 0.001). Tolamolol had no effect on His-Purkinje system conduction time as well as the relative refractory period, measured before and after the drug in 2 patients. In 6 patients, during the induction of extrastimuli an "echo zone" appeared; after tolamolol its duration was reduced in 4 patients, in one unchanged and in one abolished. The therapeutical properties of this drug are discussed on the basis of such experimental data.

Adolescent↗
PubMed1976

Left ventricular parietal block: diagnostic and clinical study.

Fifty-five patients with widened QRS complexes due to the presence of slurred S waves or of terminal slurrings on R waves, in more than three leads, with no infarction or bundle branch and fascicular blocks, were studied with the usual clinical examinations as well as vectorcardiographic recording. A parietal block of the left ventricle was diagnosed when, in the presence of a normal development of ventricular depolarization in the initial and middle phases, the terminal QRS loop was delayed, sometimes irregular and displaced leftward and posteriorly. When this delay was directed to the right, the ventricular localization was puzzling. The comparison of the electrocardiographic (ECG) and vectorcardiographic (VCG) data on the terminal part of ventricular depolarization showed some discrepancies and revealed the greater importance of VCG investigation for the study and the localization of parietal blocks. The pathogenesis of such minor conduction disturbances is not yet clear, since the experimental data on the anatomical-functional structures are different: the Purkinje network, Purkinje fiber-muscle junction or common myocardium. In some cases we think it is possible to localize the structure concerned; in any case we can always localize it at the level of the free ventricular wall.

Adolescent↗
PubMed1976

Mitochondria-rich cells of frog skin in transport mechanisms: morphological and kinetic studies on transepithelial excretion of methylene blue.

The following study combines histological observations on the localization and density of mitochondria-rich cells with a kinetic study of the part played by these cells in transport phenomena. In the ventral skin, mitochondria-rich cells and granular cells are equally abundant in the first living cell layer. The mitochondria-rich cells were shown to excrete methylene blue [3,9-bis-(dimethylamino)-phenozathionum chloride]. A kinetic study of this excretion across the isolated epithelium of Rana esculenta skin showed that the mechanism of the excretion was a saturable one. An important fraction of methylene blue excretion depends on the absorption of sodium; the absence of this ion, or the inhibition of its transport by ouabain or amiloride, inhibits the excretion of the organic base. The mitochondria-rich cells, however, do not appear to play a determining role in sodium transport.

Animals↗