Loredana Di Palma

Circadian Rhythm of Cardiac Output, Peripheral Vascular Resistance, and Related Variables by a Beat-to-Beat Monitoring

This study aimed to explore the 24-h patterns of stroke volume, cardiac output, and peripheral vascular resistance along with other correlated variables, such as left ventricular ejection time, ejection velocity index, thoracic fluid index, heart rate, and blood pressure. The study was performed on 12 clinically healthy subjects by means of a noninvasive beat-to-beat monitoring using the thoracic electric bioimpedance technique associated with the automated sphygmomanometric recording. Time data series were analyzed by means of chronobiological procedures. The results documented the occurrence of a circadian rhythm for all the variables investigated, giving relevance to the beat-to-beat bioperiodicity of cardiac output and peripheral vascular resistance. Temporal quantification of the investigated variables may be useful for a better insight of the chronophysiology of the cardiovascular apparatus.

Vasoactive intestinal peptide fluctuates in human blood with a circadian rhythm

The vasoactive intestinal peptide (VIP) may be radioimmunoassayed in systemic venous blood. The plasma concentrations of VIP were investigated in human blood according to a chronobiological design. The study documented a circadian rhythmicity in time-qualified concentrations of VIP. Accordingly, VIP may be ascribed to biological variables characterized by periodicity in their physiological attributes. The rhythmic physiology of VIP is, however, highly disturbed in its tonic and phasic properties during senescence.

Usefulness of twenty-four-hour blood pressure patterns and response to short-term sodium restriction in normotensive subjects in detecting a predisposition to systemic arterial hypertension

Twenty clinically healthy subjects were studied to identify normotensive adults with a predisposition to arterial hypertension by monitoring blood pressure (BP) and restricting dietary sodium intake. Short-term restriction in sodium intake resulted in a decrease of the mean level for the circadian rhythm of BP. The phenomenon is visible in subjects without familial hypertension but not in individuals with a positive history for high BP. The response of the 24-hour BP patterns to abrupt sodium deprivation seems to be an indicator for discovering normotensive subjects at risk of developing arterial hypertension.

Parallelism test on microcomputers for statistically comparing regression lines of bivariate data sets

Biomedical research is frequently confronted with regression lines that directionally describe the trend of phenomena, each one represented by a set of correlated x and y data. There could be a need to verify whether the regressions lines of two (or more) phenomena are statistically comparable in their slopes and intercepts, in order to draw conclusions about the similarity or dissimilarity of the conditions under scrutiny. The parallelism test the principles and methodology of which are presented here addresses this problem. A program for microcomputers is supplied as a non-profit software that can be freely shared on the understanding that the copyright belongs to the authors of this article.

Blood pressure 24-hour pattern in two industrialized countries (Italy and Japan) with a different culture in salt intake.

This study investigates the blood pressure (BP) 24-hour pattern in representative samples of 2 industrialized countries, Italy and Japan, showing different cultures in salt intake. BP was monitored by means of a noninvasive ambulatory device whose readings were analyzed by means of chronobiometric procedures. The results show that the 24-hour BP pattern is not substantially different in Italian and Japanese subjects. In particular, the expected lower BP in the Italians was not detected despite their lower salt intake. Because the 24-hour mean BP value was seen not to be proportional to salt intake, the hypothesis is formulated that maintenance of the pressure regimen within a given range of variability is a principle of human physiology. To comply with this rule the Japanese people are supposed to have ethnically developed a certain resistance to dietary salt for which their cardiovascular apparatus is protected (phyletic escape to dietary sodium excess).

Gestational Blood Pressure Monitoring and its Chronobiometric Quantification

Blood pressure (BP) monitoring is a clinical reality because of the availability of non-invasive automated recorders. BP 24-h patterns were explored during physiologic pregnancies in order to obtain time-qualified standards for clinical use. Non-inferential and inferential reference boundaries were computed by using chronobiometric procedures. The computed confidence limits provide a set of reference standards that serves to optimize the diagnosis of pregnancy-induced deviation in BP 24-h patterns.

Cosint analysis: A procedure for estimating biological rhythms as integral functions by measuring the area under their best‐fitting waveform profile

Abstract Presently, the chronobiometric procedures are eminently descriptive estimating the biological rhythms in their parameters without computing the integral measure of their periodic oscillation. The evaluation of the rhythm as a global function is fundamental in biomedical science as its integral estimate allows the correlation with biological events whose expression depends on the effects of time. In order to provide an integration method for biological rhythms, it has been developed a periodic integration analysis, called Cosint method. Its mathematical basis is explained. The integral estimate is represented by the parameter AESOR, acronym of Area Estimating Statistic Of Rhythm, which corresponds to the area under the curve provided by the analytical fits of a cosine function to the time data series. The AESOR can be computed on the waveform profiles resulting from the fit of mono‐ or multiple‐component models of harmonic analysis. The AESOR may estimate the biological rhythms in their entire per...