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Biomedical subjects

D Scavo

Publications and source records attributed to D Scavo.

At least 73 records · Page 4Linked to original sources
PubMed1987

Occurrence of a circadian rhythmicity for blood pressure in patients with circulatory shock.

Ten patients hemodynamically in shock were monitored for blood pressure along the 24-hr span while under antishock therapy. Time-qualified data were analyzed by means of the cosinor procedure. The fit of a 24-hr cosine function was able to reject the null hypothesis of amplitude = O in the majority of patients under intensive care. The blood pressure circadian rhythm was found to be independent of whether the patient was responsive or refractory to therapy. This phenomenon demonstrates that the maintenance of a blood pressure circadian rhythm is a characteristic intrinsic to hemodynamic shock even if blood pressure falls to very low values along the time scale.

Adult↗
PubMed1987

Postural effects on the circadian rhythm of blood pressure and heart rate in young and elderly subjects.

This investigation compares the effects of changes in activity-rest patterns on the 24-hr rhythms of blood pressure and heart rate in elderly and young subjects. Blood pressure and heart rate were monitored by means of noninvasive, automatic, quasiportable recording equipment. The subjects either rested both diurnally and nocturnally or were active diurnally and rested nocturnally. Time-qualified data were analyzed for circadian rhythmicity by means of the cosinor procedure. In both activity-rest patterns, elderly subjects showed a dissociation between circadian rhythms of blood pressure and heart rate due to a peculiar shift of acrophases. Because of the particular timing of the acrophase, elderly subjects differed from young individuals in the overall adaptation of the blood pressure and heart rate 24-hr patterns to upright posture and physical activity. Of particular interest is the reduced amplitude in the circadian rhythm of blood pressure, which might contribute to the compromised orthostatic tolerance of older people.

Adolescent↗
PubMed1986

Hyperendorphinemia in obesity and relationships to affective state.

Eight obese patients (exceeding ideal body weight by 50% or more) with no endocrinological or metabolic disorders and 8 healthy, age-matched, normal-weight volunteers were submitted to an overnight short dexamethasone (DXM) suppression test and to a psychological assessment through various psychometric scales. Plasma B-Endorphin (B-EP), B-Lipotropin (B-LPH), ACTH and cortisol concentrations were evaluated in basal conditions, as well as 9 and 17 hours after late night administration of 1 mg DXM in both groups. All hormones were measured by radioimmunoassay, either directly in the plasma (ACTH and cortisol) or after silicic acid extraction and Sephadex G-75 column chromatography (B-LPH and B-EP). In obese patients, plasma B-EP levels in basal conditions were three times higher than in normal weight controls and remained unaltered by DXM suppression. ACTH and B-LPH, in contrast, were within the normal range and were significantly reduced by DXM. In 3 of the 8 patients, plasma cortisol concentrations at 17 hours post-DXM were greater than 50 ng/ml indicating an early escape from the suppression. Psychometric evaluations revealed a prevalence of depressive personality in obese patients. These data indicate an hypersecretion of B-EP in obese patients, which is only partially dependent on hypothalamic control.

Adrenocorticotropic Hormone↗
PubMed1986

[Disorders of renin secretion in arterial hypertension].

The present work is devoted to investigate the meaning of disorders in renin secretion in primary and secondary hypertension and report the results of bayesan analysis applied to a group of 125 hypertensives who underwent selective renal angiography and polydistrictual renal vein samplings for the determination of plasma renin activity for diagnostic and therapeutic purposes. Data obtained from statistical analysis allow specifications on the prevalence of disorders, rates of false positives and false negatives, predictive value, diagnostic value, sensitivity and specificity. The weighted data are useful to validate the reliability of the renin renal vein measurements which are used in clinical practice for identifying the potentially surgically curable forms of arterial hypertension.

Adolescent↗
PubMed1985

Temporal correlation of some endocrine circadian rhythms in elderly subjects.

The aim of this chronobiological study was to investigate temporal correlations in the circadian patterns of 6 hormones, namely somatotrophic hormone (STH), prolactin (PRL), cortisol (F), aldosterone (ALD), insulin (IRI) and C-peptide (CP), assayed in systemic blood serum drawn at 07:00, 10:00, 13:00, 16:00, 19:00 and 22:00 h from an antecubital vein in 19 young subjects (aged 20-29 yr, comprising 10 males and 9 females; and 20 elderly subjects (aged 70-81 yr, comprising 10 males and 10 females). All subjects were sampled on a normal dietary sodium intake (120-140 mEq/24h) while following a social routine of diurnal activity (07:00-23:00) and nocturnal rest (23:00-07:00). Time-qualified data were analyzed by lead-lag correlation and by cosinor analysis. According to the lead-lag correlation findings, it would appear that the correlation which exists between several time-qualified series in young subjects is no longer present in elderly subjects. The circadian rhythms which were found to have lost their temporal correlations with advancing age were those between STH and IRI, STH and ALD, PRL and IRI, PRL and CP, and ALD and CP. It should be noted that the correlation between hormonal rhythms breaks down mainly on account of a peculiar age-related change in the magnitude of the circadian fluctuation. This chronological decline in amplitude led to the conclusion that the senescence of endocrine rhythmic functions is a biological phenomenon characterized by altered circadian variability.

Adult↗
PubMed1985

Circadian rhythms of plasma renin activity and aldosterone: changes related to age, sex, recumbency and sodium restriction. Chronobiologic specification for reference values.

Plasma renin activity (PRA) and aldosterone (PA) levels are characterized by a circadian rhythmicity (CR). The present study revealed that this rhythmicity is influenced by several factors including posture, sodium intake and age. Time-qualified PRA and PA reference intervals can reduce the incidence of false positives and false negatives in a diagnostic work-up. The circadian rhythmicity of PRA and PA have been quantified in relation to posture, sodium intake and age. The cosinor procedure has been applied to quantify the properties of the circadian rhythmicity under these conditions. Chronograms and circadian parameters can be used to optimize the use of PRA and PA measurements in clinical practice. The chronobiological specification of reference values for PRA and PA is of valuable importance since the assessment of PRA and PA circadian rhythmicity has a diagnostic interest for a certain type of clinical disorder. It should be noted that several studies have described circannual variations for renin and aldosterone. The next step in the optimation of laboratory time-qualified reference values is the assessment of changes induced by the deterministic factors on a circannual domain.

Adult↗
PubMed1984

[Clinical significance of anomalies of renin secretion in arterial hypertension].

Aim of the present investigation is to define the clinical meaning of disorders in renin secretion in the field of vascular hypertensive diseases. In view of this scope, we report the results of a retrospective study on the levels of plasma renin activity assayed in renal veins, aorta and peripheral vein of 124 hypertensive, angiographically studied for a diagnostic work-up. The behavior of renal vein renin has been related to epidemiologic, clinical and etiopathogenetic factors. Results indicate that disorders in renin secretion occur in every type of arterial hypertension. However, some disorders are prevalent in a determined type of hypertensive disease. The incidence of disorders in renin secretion is different in relation to sex, age and duration of hypertension. Hypersecretion is prevalent in men and young hypertensives, while hyposecretion of renin is more frequent in the oldest hypertensive patients. Vascular damage is prevalent in men and young hypertensives, while hyposecretion of renin is more frequent in the oldest hypertensive patients. Vascular damage is prevalent in renin hyposecretive hypertensives. Hypersecretion and lateralization in renin release can be mainly encountered in the renovascular type of hypertension and, less frequently, in unilateral nephroparenchymal hypertension. However, totally lateralized hypersecretion can be detected even in essential hypertensive patients suggesting the possibility of false positives for the diagnosis of renovascular hypertension.

Adult↗
PubMed1984

Circannual versus seasonal variations of longitudinally sampled 25-hydroxycholecalciferol serum levels.

Seasonal variations in human serum levels of 25-hydroxycholecalciferol (25OHD) have been largely documented in transverse studies of population. But seasonality is not per se a demonstration that 25OHD serum levels fluctuate along the course of year according to a waveform profile with a periodic rhythm. Because of this, we attempted to investigate the possible occurrence of a circannual rhythm for 25OHD serum levels in a longitudinal design, by fitting a 365.25-day cosine curve to temporal biodata recorded in 10 clinically healthy subjects, monthly sampled for RIA determinations of 25OHD. Cosinor procedure statistically validated the occurrence of a circannual rhythm for 25OHD serum concentrations at a highly significant level of probability (P = 0.0015) for null hypothesis amplitude = 0. With 95% of probability, amplitude ranges from 5.0 to 16.5 ng/ml (mean value of oscillation = 10 ng/ml), while acrophase is temporally located from September 14 to December 3 (mean timing = October 21). Yearly, mean values for 25OHD serum concentrations is of 40.3 +/- 5.4 ng/ml as quantified by the line which transversely divides the cosine curve interpolating original biodata. By calculating the band of a complete 12 months variability which includes 90% of the distribution with 90% confidence limits, the circannual chronodesm of 25OHD serum levels has been obtained. Such a chronodesmic sinusoid has been compared to the circannual chronogram. By this comparison, a dissociation between the crest (October) and the peak (August) has been detected. The finding suggests that seasonal variations are superimposed to the circannual rhythm. Seasonal but also circannual changes, thus, characterize the yearly variability of 25OHD serum levels in man.

Adult↗
PubMed1984

Toward a chronophysiology of circulating aldosterone.

The physiology of aldosterone secretion has been prominently investigated by homeostatic studies on the levels of the steroid in plasma and/or urine. Aldosterone secretion is, however, arranged in a rhythmic fashion along the 24-hr cycle. The dynamics of aldosterone should thus be reanalyzed chronobiologically in order to gain further insight into the physiology of the hormone. Such a revisitation has been performed in the present study on four groups of clinically healthy volunteers categorized according to sex and age. Aldosterone has been assayed in the plasma of systemic venous blood six times a day (0600, 0800, 1200, 1800, 2000, 0000) in different conditions of physical activity and sodium intake. Time-qualified data have been analyzed by the single-cosinor method and then summarized by the population-mean cosinor procedure to quantify the circadian rhythms in their properties (mesor, amplitude, acrophase). Differences in rhythmometric parameters have been tested by a multivariate analysis for vectorial units. (Hotelling's T2 test). Cosinor analysis indicates that the dynamics of circulating aldosterone substantially changes in relation to posture. The habit of having a routine of diurnal activity leads the circadian rhythm of aldosterone to delay its acrophase from morning to afternoon. The postural shift of acrophase is essentially accompanied by an elevation in the 24-hr mean level. The restriction of salt intake is associated with an increase in mesor; the temporal localization of the circadian crest shows, however, a very high stability. Sex is not characterized by significant differences in the 24-hr patterns of aldosterone in the sense that young males and females show substantially identical time-qualified curves and circadian parameters. Increasing age until the seventh decade in life is responsible for changes mainly in 24-hr mean levels with a slight modification in amplitude. Such a chronophysiology for circulating aldosterone related to the motor-rest schedule, sodium intake, sex, and age, is of interest not only to heuristic but also to practical approaches in clinical medicine.

Adolescent↗
PubMed1984

[Parametric methods applied to the standardization of gestational reference intervals for blood renin activity, aldosterone and cortisol using the transversal and longitudinal approach].

This investigation is devoted to define monthly-qualified gestational reference intervals for plasma renin, aldosterone and cortisol as derived by transverse or longitudinal approaches. Reference intervals refer to 95% confidence interval, 90% tolerance interval, the 95% predictive interval, in addition to the mean plus or minus the standard error and standard deviation. By applying both methodological approaches it has been found that plasma renin and aldosterone exhibit a progressive gestational increase. By contrast, cortisol shows an initial increase and thereafter stays on the same values. Statistical analysis revealed the transversally--and longitudinally--derived reference intervals to be not statistically different. Because of such a similarity, laboratory medicine can interchangeably use both kinds of reference intervals for estimating the normality of plasma renin, aldosterone and cortisol values in a single case of pregnancy. This interchangeability of values leads to simplify the methodology for measuring plasma renin and aldosterone in pregnancy since it is not necessary to standardize the gestational nomograms for renin-sodium and/or aldosterone-sodium relationship. This is a real way to reduce the costs and to optimize the compliance in the monitoring of pregnancy.

Adolescent↗
PubMed1983

Circadian as well as circannual rhythms of circulating aldosterone have decreased amplitude in aging women.

Age differences in the characteristics of the circadian rhythm in circulating radioimmunoassayable aldosterone were studied on nine 20 to 26 year-old and ten 70 to 78 year-old women and ten 23 to 26 year old and ten 70 to 80 year old men in Würzburg, West Germany. These diurnally active-nocturnally resting subjects were sampled every 3 hours for 15 hours. A classical analysis of variance and a multivariate analysis of rhythm characteristics revealed major effects of age exerted on the circadian aldosterone amplitude in women (p = 0.003) but not in concomitantly sampled men. These observations complement the study of circadian and circannual rhythms in 8 young adults (15-21 years), 10 mature adults (29-36 years) and 10 post-menopausal (44-59 years) North American women, sampled at 100 minute intervals for 24 hours, once in each season, and document that the adrenocortical aldosterone-producing system remains rhythmic with at least two frequencies up to the late decades of human life, although in women it may be characterized by a reduction in the extent of spectral change after 70 years of age.

Adult↗
PubMed1983

[Differential aspects of the dynamics of the renin-angiotensin-aldosterone system in obesity with and without hypertension and in essential arterial hypertension].

This report describes the impulsive function of the RAAS investigated in obese and non-obese hypertensives as compared to obese and non-obese normotensives. The aim of the investigation was to clarify whether or not the hypertensive vascular disease accompanying the ponderal excess can be regarded as a well-defined pathophysiologic entity. Data obtained showed that the behavior of the RAAS in hypertensive obese patients is quite different from that of non-obese hypertensives and obese normotensives. Such a difference implies that hypertension of obese people is a biochemically distinguishable entity. This observation corroborates the concept that the clinical association of obesity-hypertension might be regarded as a syndrome with a proper nosographic dignity.

Adult↗