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Biomedical subjects

V Moretti

Publications and source records attributed to V Moretti.

At least 19 recordsLinked to original sources
PubMed1993

A 31P NMR spectroscopy study of Xenopus laevis heart perfused in vitro with creatinol-O-phosphate, phosphocreatine, adenosine triphosphate, fructose diphosphate and ouabain.

Xenopus laevis heart was studied by 31P NMR using a 200 MHz proton spectrometer; hearts were perfused, at pH 7.35 and room temperature, with normal oxygenated or K(+)-enriched Ringer. Solution was later added with creatinol-O-phosphate (COP), phosphocreatine (PCr), adenosine triphosphate (ATP), fructose-1,6-diphosphate (FDP) and ouabain. NMR spectra of the heart show organic phosphomono- and phosphodi-esters, inorganic phosphate, PCr, overlapping alpha-ATP/ADP and gamma-ATP/beta-ADP, and beta-ATP signals. Their chemical shift positions and areas showed no significant changes in the course of 1.5 h perfusions with either solution, except in a few preparations, whether the heart was beating or reversibly arrested. While COP reduced the signals in beating hearts, the same spectra exhibited no consistent, substantial changes under PCr, ATP and FDP 1 to 10 mM, pH 7.35 perfusion with either solution, nor when ouabain mumol was added. The spectra are briefly discussed in comparison with those observed in the perfused heart of mammals (mostly rat), and particularly with those obtained in the frog (Rana temporaria) heart, both by analysing the bioenergetic equilibria on the basis of total tissue substrate levels measured in extracts of freeze-clamped tissue, and by evaluating cytochrome-b, flavin and pyridine nucleotide in vitro oxido-reduction read-outs in separate, similar experimental settings.

Adenosine Triphosphate↗
PubMed1993

Non invasive evaluation in cerebrovascular study: possibility and prospects.

The authors outline the importance of the global investigation of the cerebrovascular system in order to obtain more exact information about the ethiopathology of vascular ischaemic brain disease. Each patient is always submitted to the following investigations: Duplex scanner of epiaortic vessels, Transcranial doppler and echocardiographic screening in our vascular laboratory; moreover, when haemodynamic carotid artery stenosis is present, duplex scanner of femoro-popliteal vessels and microcirculatory study of the brain with Zenon133, via inhalation, were undertaken. In the second part of the study the authors refer a relationship between the instrumental doppler signal and the real risk evidenced by techniques which can provide information on the composition, structure and stability of the plaques and correlate this information with the data from the doppler analysis. Instrumental techniques such as thermal analysis, atomic absorption spectroscopy, ICP analysis and IR spectroscopy were used to carry out this study.

Cerebrovascular Circulation↗
PubMed1991

Electrophysiological effects of a pumiliotoxin-B-like alkaloid derived from the skin of the Australian frog Pseudophryne coriacea.

Skin extracts of the Australian frog Pseudophryne coriacea (PsC) potentiate and prolong the bioelectric activity of various excitable tissues. When studied by electrophysiological means in a preparation of mouse diaphragm, PsC skin extracts did not affect the spontaneous acetylcholine (ACh) release. However, the indirect stimulation of the preparation in the presence of PsC skin extracts gave rise to a different profile of rhythmic activity showing afterpotentials and variable oscillatory activity. The action potential and the total sodium current recorded in the muscle fibre with the loose patch clamp method were not modified significantly by the alkaloid. Concentrations of PsC skin extract that did not cause repetitive activity, seemed to reduce slightly the quantal content of the evoked release of ACh. The resting potential of muscle fibres was not modified even by the highest PsC skin extract concentrations. These results suggest that the facilitation effects of PsC skin extracts could be due to intracellular mechanisms probably related to the control of the cytosolic calcium concentrations or to an increased excitability of the presynaptic biomembranes.

Acetylcholine↗
PubMed1990

Sodium-activated potassium current in mouse diaphragm.

The mouse diaphragm muscle fiber was studied using the loose patch clamp technique. The voltage gated sodium currents were evoked by step pulses from a holding potential of about - 70 mV. Following the activation of the sodium current, a very large and fast outward current was evoked. The sensitivity of this current to 4-aminopyridine and tetraethylammonium indicates the potassium ion as the possible carrier for the channel. Furthermore, the sensitivity to tetrodotoxin and extracellular sodium demonstrated the sodium dependence of this current.

Action Potentials↗
PubMed1989

Characterization of the rabbit aorta endothelium-dependent cholinergic receptor by agonist equipotent molar doses.

The endothelium-dependent acetylcholine, metacholine, carbachol, betanechol, and furtrethonium relaxation values have been measured in vitro for the rabbit aorta, in presence of a high concentration of hexamethonium. The produced EPMR values complete the values that were obtained in a previous experiment under analogous conditions for rat bladder, ileum, iris, stomach, and trachea preparations. The complete set was analyzed by new statistical techniques of data analysis and display, which are both simpler and more precise than the statistical modeling techniques used by us in the past. This has led to new results concerning the clustering of drugs and of receptors, as well as to a characterization of the endothelium receptor.

Animals↗
PubMed1989

[Is serotonin implicated in the pathogenesis of the alcohol abstinence syndrome?].

5-Hydroxyindoleacetic acid (5-HIAA), the main metabolite of 5-hydroxytryptamine or serotonin, excreted in the urine over a 24 hour period was systematically measured in 35 patients with alcohol withdrawal syndrome (AWS). The level of excreted urinary 5-HIAA ac. was high in only a few patients. The pathogenic mechanisms involved are discussed and though the role of serotonin in the pathogenesis of AWS seems of secondary importance, some 5-hydroxytryptamine methyl analogues may have a major role in the pathogenesis of hallucinations caused by alcohol withdrawal.

Adult↗
PubMed1987

[Pituitary prolactin reserve in acute exacerbation of chronic respiratory insufficiency].

The level of pituitary prolactin reserve (PPR) was studied in 56 patients with chronic respiratory failure (CRF) in the acute stage after injections of metoclopramide and Thyrotropin Releasing Hormone (TRH). PPR was low in 90% of the subjects in both groups so that the pathogenic mechanism is more likely to be hypophyseal than hypothalamic and due to the reduced synthesis of PRL by the pituitary gland as a result of inadequate ATP synthesis and/or functional alterations to the receptors or pituitary cells following hypoxaemia and hypercapnia.

Acidosis, Respiratory↗