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Biomedical subjects

D Scavo

Publications and source records attributed to D Scavo.

At least 91 records · Page 5Linked to original sources
PubMed1982

Effect of ageing on circadian rhythms of plasma renin and aldosterone in mesor-hypertensive women.

This study investigated the changes in circadian rhythms of plasma renin activity (PRA) and plasma aldosterone (PA) which occur in essential mesor-hypertensive women, increasing in age. Systemic blood samples were taken throughout a 12 h period from both mesor-hypertensive women and clinically healthy women (control). The women in each group were either post-menopausal or had normal menstrual cycles. A cosinor method of temporal series was the analysis employed to compute the properties of PRA and PA circadian rhythms. The clearest effect of ageing, recorded in essential mesor-hypertensive women, is a decrease in circadian mesor of PRA cycle (P = 0.002). The age-related changes in clinically healthy women appear to be more extensive and involve a decrease for both mesor (P less than 0.001) and amplitude (P = 0.007) of PRA circadian rhythm. These disparities are convincing evidence for a non-physiological decline of the RAAS rhythmic function in the aged essential mesor-hypertensive women. The lack of an age-associated decrease in circadian PRA amplitude merits and pathophysiological and clinical investigation because it is a possible risk factor for post-menopausal, essential mesor-hypertensive women.

Adolescent↗
PubMed1982

Methodologically critical interactions of circadian rhythm, sex, and aging characterize serum aldosterone and the female adrenopause.

Nine 20- to 26-year-old and ten 70- to 78-year-old diurnally active, nocturnally resting women in Würzburg, Federal Republic of Germany, gave blood at 0700, 1000, 1300, 1600, 1900, and 2200 for radioimmunoassay of aldosterone. Single and population-mean cosinors were applied. A multivariate analysis of circadian rhythm characteristics revealed effects of age on the amplitude (p = .003) but not the mesor of aldosterone in women (i.e., the age effect could only be detected at certain circadian times but not at others). No change with age was found for concomitantly sampled men. Statistically significant interactions among circadian time, age, and sex (p = .001) establish the adrenocorticopause in women and suggest that it may occur earlier in women than in men, in keeping with similar results on serum cortisol in the same subjects. This phenomenon awaits scrutiny from the viewpoint of its bearing on longevity and life quality. These results also indicate the importance of assessing chronobiological characteristics.

Adult↗
PubMed1982

[The influence, in normal subjects, of a high-protein normocaloric diet on the response of cortisol, ACTH, GH, and PRL to insulin hypoglycemia].

A protein rich diet causes a remarkable increment of plasma cortisol, corticotropin and somatotropin concentration, but does not modify the plasma prolactin level; this diet, moreover, is followed by a more vivacious response to the Lysin-8-Vasopressin test. In 10 healthy voluntary subjects we have studied the hormonal behaviour during the insulin-induced hypoglycemia test in course of equilibrated diet and after 15 days of protein-rich diet. In these two experimental conditions the insulin-induced hypoglycemia test has promoted a similar increment of the four hormones. The different behaviour between the two tests -Lysin-8-Vasopressin and insulin-induced hypoglycemia- indicates that the increased hormonal levels which follow a protein-rich diet are not provoked by a generic stress effect, but by a direct stimulation of the hypothalamo-hypophyseal structures.

Adolescent↗
PubMed1982

Inactive and active renins, aldosterone and cortisol in puerpera and newborn.

Eleven primiparae (aged from 20 to 31 years) have been sampled at the time of partum and throughout the puerperium for simultaneous determinations of plasma levels of inactive (prorenin) and active (PRA) renins, aldosterone (PA) and cortisol (PC). Biodata have been compared to time-qualified values obtained in non-pregnant adult women (aged from 17 to 37 years). Pregnant women show peripartum levels of prorenin, PRA, PA and PC significantly higher than the time-qualified reference intervals. Gestational increment is meanly of 3-4 times for prorenin, of 5-8 times for PRA, of 17-19 times for PA, of 4-5 times for PC. Puerperal levels of PRA, PA and PC show a progressive decline while those of prorenin suddenly fall and then remain quite stable. Neonatal levels of prorenin, PRA, PA and PC are higher than normal. Neonates show levels of prorenin, PRA, PA and PC, respectively equal, increased equal and decreased when compared to mothers. The different equipment of hormonal levels in mother and newborn leads to suggest a selective role of the placenta as a filter.

Adult↗
PubMed1982

[Circadian rhythm of temperature, heart rate and blood pressure in normal rats and hypothyroid rats].

We explored the circadian variation of core temperature, heart rate and blood pressure in hypothyroid and euthyroid male Sprague-Dawley rats. A circadian rhythm was quantified by the population mean-cosinor method for the core temperature of both hypothyroid and intact rats, whereas for the blood pressure and heart rate values a circadian rhythm was validated by rejection of the zero-amplitude assumption only in the hypothyroid rats. Whether hypothyroid rats adjust to new schedules at a rate different from euthyroid animals is an inference from these studies awaiting scrutiny.

Animals↗
PubMed1981

[Influence, in normal subjects, of an isocaloric hyperprotein diet on cortisol, ACTH, GH and PRL response to lysine-8-vasopressin].

The Lysin-8-Vasopressin test has been experimented in ten healthy subjects during normocaloric balanced diet and after hyperproteic-normocaloric diet. The levels of ACTH, Cortisol and GH are significantly more elevated after hyperproteic-normocaloric diet than in basal conditions. The levels of Prolactin do not show any remarkable change. These results can indicate the increased reactivity of the diencephalon-hypophysis-adrenal axis and of the hormones connected with the mechanisms of homeostasis and stress, probably correlated to more disposable proteic material and to the metabolic effects which follow.

Adrenocorticotropic Hormone↗
PubMed1981

Ageing and circadian rhythm of plasma renin and aldosterone.

Five men and 8 women, 60-69 yr of age, and 4 men and 5 women, 17-37 yr of age, volunteered for this exploration of possible age-related changes in circadian-rhythm (CR) characteristics of radioimmunoassayable plasma renin (PRA) and aldosterone (PA). Blood was drawn at 06.00, 08.00, 12.00, 18.00, 20.00 and 24.00 from recumbent subjects on a habitual sodium intake of 120-140 mEq/24 h. Time-qualified data of PRA and PA, fitted by a 24-h cosine curve, were summarized by a population mean-cosinor method. Circadian characteristics were compared by a multivariate analysis using Hotelling's t2 test. Rhythmometry reveals in the elderly women a lower mesor (P less than 0.001) and amplitude (P = 0.036) of the CR in PRA and a higher mesor and amplitude (P = 0.021 and P = 0.020, respectively) of the PA-CR. The PRA acrophase is delayed (P less than 0.001) in the elderly women (04.40 vs. 08.04) while the timing of the PA acrophase is similar in the age groups of women compared (05.52 vs. 05.20). These differences found in women were not observed in the smaller groups of men. The seventh decade of life may be characterized by an internal circadian desynchronization between the major components of the renin-angiotensin-aldosterone system. A sex-dependent amplification of the extent of circadian variation in aldosterone may precede a decrease in the circadian amplitude occurring during the eighth decade of life, as a sign of the adrenopause in women.

Adolescent↗
PubMed1981

Circadian rhythms of plasma renin, aldosterone and cortisol on habitual and low dietary sodium intake.

To examine the effects of reducing sodium intake upon the renin-angiotensin-aldosterone system (RAAS), 5 healthy men and 5 healthy women, 17-37 years old, living under standardized conditions, were sampled around the clock, once on habitual and once on restricted sodium intake. Plasma renin activity (PRA), aldosterone (PA) and cortisol (PC) were determined by radioimmunoassay. All three variables were found to exhibit a statistically significant circadian rhythm, both on habitual and restricted salt intake. After salt restriction, an increase in midline-estimating statistic of rhythm (mesor) of PRA and PA, but not of PC, was observed. The acrophase (an estimate of the time of high values) for PC lagged behind that for PRA and PA. This difference in acrophase was of specially high statistical significance when subjects were on a sodium-restricted diet. These results demonstrate the importance of inferential statistical so-called rhythmometric methods: parameters such as the acrophase can also be used for the assessment of novel effects and for a quantification in time. The derivation of confidence intervals for each rhythm parameter allows one to verify that a given variable exhibits values bracketing an average not only between a higher and a lower, but also between an earlier and a later limit. Changes that may involve only the acrophase, such as a lead or lag, as here noted, are then detected and are of factual as well as methodological interest.

Adolescent↗
PubMed1980

Beta-adrenergic regulation of circadian rhythmicity of the renin-angiotensin-aldosterone system in five subtypes of essential hypertension.

The possible implication of the beta-sympathoadrenergic system in regulating the rhythmicity of the renin-angiotensin-aldosterone system (RAAS) was studied in ten normotensive volunteers and in thirty-nine essential hypertensive patients. The study was carried out by simultaneous radioimmunological measurements of diurnal levels of plasma renin and aldosterone before and during acute oral medication of beta-adrenoceptors with propranolol. Acute beta-blockade was seen to blunt the circadian periodicity of plasma renin and aldosterone in normotensives and in hypertensives with normal or high renin patterns. Conversely propranolol was seen to be ineffective in low-renin patients. The disappearance of the circadian rhythms under beta-adrenoceptor blockade tends to suggest the existence of a beta-adrenergic control of RAAS cyclicity in normal condition, as well as in normal or high renin essential hypertension. The inefficacy of propranolol in hyporeninemic hypertensives is consistent with the hypothesis that low-renin essemtoa; juertemsopm os a state in which the sympatho beta-adrenergic mechanism controlling the function of RAAS has no biologic time structure.

Adolescent↗
PubMed1979

[Temporal aspects of the function of the renin-angiotensin-aldosterone system. Contribution to the methodological standardization of explorative test (author's transl)].

The purpose of this study is to throw further light on the problem of the methodological standardization in the study of the renin-angiotensin-aldosterone system (RAAS). Thus, in 10 normal volunteers and 33 patients with moderate, recent and uncomplicated essential hypertension, divided into the subtypes with normal, high and low renin, it has been performed a timing analysis of the behaviour of plasma renin (PRA) and aldosterone (PA). PRA and PA were measured by radioimmunological methods in blood samples simultaneously collected in steady state conditions (study of circadian rhythmicity) and during the course of manipulative tests (orthostatism, dietary sodium restriction, orthostatism associated with sodium restriction, furosemide administration). The study revealed that each category of the present series of healthy and hypertensive individuals has an own temporal organization in the entire function of RAAS. This finding allowed to standardize the RIA reference indices as chronocorrelated intervals of normality and to establish the optimal criteria for the assessment of biochemical data and methodological study of hypertensive patients.

Adolescent↗