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Biomedical subjects

S Cerutti

Publications and source records attributed to S Cerutti.

At least 163 records · Page 9Linked to original sources
PubMed1984

Power spectral density of heart rate variability as an index of sympatho-vagal interaction in normal and hypertensive subjects.

Instantaneous heart rate reflects sympatho-vagal influences on pace-maker activity. Hence computer analysis of heart rate variability might provide a quantitative index of that interaction. The power spectral density (PSD) estimate of heart rate variability was obtained in normal controls and in uncomplicated hypertensives, both at rest and during a non-hypotensive sympathetic stimulus (tilting). In normal controls PSD shows three major peaks of frequencies P1 = 0.07, P2 = 0.12, P3 = 0.25 cycles/beat. P1, which is associated with sympathetic activity, represents only a minor portion of total variability at rest, while becoming predominant with tilting. P2 and P3 are associated with vagal activity, and represent the major part of variability at rest, while they are reduced by tilting. In hypertensive patients PSD is altered, as P1 is already predominant at rest and increases only slightly with tilting. Thus PSD of heart rate variability is capable of detecting an early alteration in sympatho-vagal balance of cardiac control present in uncomplicated hypertension.

Adult↗
PubMed1983

An optimal linear filter for the reduction of noise superimposed to the EEG signal.

In the present paper a procedure for the reduction of super-imposed noise on EEG tracings is described, which makes use of linear digital filtering and identification methods. In particular, an optimal filter (a Kalman filter) has been developed which is intended to capture the disturbances of the electromyographic noise on the basis of an a priori modelling which considers a series of impulses with a temporal occurrence according to a Poisson distribution as a noise generating mechanism. The experimental results refer to the EEG tracings recorded from 20 patients in normal resting conditions: the procedure consists of a preprocessing phase (which uses also a low-pass FIR digital filter), followed by the implementation of the identification and the Kalman filter. The performance of the filters is satisfactory also from the clinical standpoint, obtaining a marked reduction of noise without distorting the useful information contained in the signal. Furthermore, when using the introduced method, the EEG signal generating mechanism is accordingly parametrized as AR/ARMA models, thus obtaining an extremely sensitive feature extraction with interesting and not yet completely studied pathophysiological meanings. The above procedure may find a general application in the field of noise reduction and the better enhancement of information contained in the wide set of biological signals.

Computers↗
PubMed1982

An automatic procedure for pre-processing ECG/VCG signals.

An automatic procedure for the pre-processing of ECG/VCG signals has been implemented on a HP2100 computer in order to test the significance of a few algorithms for the reduction of low-frequency and high-frequency noises superimposed on the tracings, i.e. baseline-drift evaluation and correction, low-pass and high-pass analogue and digital filterings. It is shown that such operations diminish the influence of noise and improve the phase of feature extraction in the processing program for a better measurement of wave amplitudes, durations and intervals. Such aspects are considered fundamental due to the increasing applications of 24-h Holter type recording, microprocessor-based modules both in the cardiological field and in patient monitoring systems, besides taking into account the new design concept of electrocardiographic equipments which, in the future, will become more and more a sort of data acquisition modules.

Computers↗
PubMed1981

A method for the quantification of the decision-making process in a computer-oriented medical world.

The aim of this paper is to suggest an original approach to the decision-making process in a computer-oriented medical record, now in use on an experimental basis, at a major District Hospital in Sesto S. Giovanni, near Milano, in a general medicine department. Two types of algorithms are introduced in order to 'capture' more effectively the different steps of the decisional process on the basis of a differential diagnosis approach. The first refers to the field of symbolic reasoning, close to the area of Artificial Intelligence and uses score variables, while the other can handle qualitative expressions since it follows the fuzzy-set approach. A comparison among the performances offered by such algorithms, the physician's decision and the Bayes Rule is then carried on. Further developments should clarify the problems of parameter sensitivity as regards the successive steps to the final diagnosis. The present implementation is suitable for individual hospital departments and educational purposes.

Decision Making↗
PubMed1978

Pharmacological profile of BR-931, a new hypolipidemic agent that increases high-density lipoproteins.

BR-931 [4-chloro-6-(2,3-xylidino)-2-pyrimidinylthio-(N-beta-hydroxyethyl)-acetamide], a new hypolipidemic agent of low toxicity, was evaluated in several tests of lipolysis and hyperlipidemia in rats, and in the cholesterol-induced atherosclerosis in rabbits. Significant hypolipidemic activity was observed in rats with doses of the agent at 12.5--50 mg/kg. In the Triton-induced hyperlipidemia, 50 mg BR-931 per kg was equieffective as 200 mg of clofibrate (CPIB) per kg. In contrast with CPIB, BR-931 exerted a powerful antilipolytic activity against epinephrine, ACTH, nicotine and cold exposure. BR-931 was particularly effective in diet-induced hyperlipidemias. Ethanol lipemia was totally prevented by the agent at 100 mg/kg. With Nath's diet, doses as low as 25 mg/kg significantly reduced hypercholesterolemia and hypertriglyceridemia. In these last two tests, the distribution of lipoprotein cholesterol was also determined. CPIB did not affect HDL cholesterol levels that had been decreased by the diets; in contrast, BR-931, already at doses of 50 mg/kg, brought the HDL/total cholesterol ratio back toward normal. A significant HDL cholesterol increase, together with some reduction of atheromatosis, was also observed in cholesterol-fed rabbits. BR-931, a potent inducer of liver peroxisones and of mitochondrial carmitine acetyltransferase, appears to be a hypolipidemic agent of high efficacy and low toxicity for the clinical treatment of hyperlipidemias and atherosclerosis.

Acetamides↗