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Biomedical subjects

F Ceresa

Publications and source records attributed to F Ceresa.

31 records · Page 2Linked to original sources
PubMedDate not supplied

The coronary vasculature and the myocardium.

The effect of bradykinin (BK) on myocardial inotropic state was tested on 5 isolated rat heart preparations, in which a proper ballon was placed to record left ventricular pressure, whose developed systolic value was taken as an index of contractility. A reduction of developed left ventricular pressure was observed when BK was added to the perfusion oxygenated Tyrode solution. However, when BK was given after 1-amino-benzotriazole, an inhibitor of Cytochrome P-450 (Cyt P-450), developed pressure did not change. Since Cyt P-450 is known to act on arachidonic acid inducing the production of epoxiecocistrienoic acids (EETs) which hyperpolarizes myocardial fibres, it was argued that the reduction in contractility by bradykinin was the result of the hyperpolarizing effect of EETs. The fact that the concentration of Cyt P-450 is higher in the vascular endothelial cells than in the sarcolemma of the myocytes and the observation that the coronary resistance decreases together with the contractility suggest that the endothelium plays a pivotal role in mediating the negative inotropic effect of BK.

Animals↗
PubMedDate not supplied

Circadian rhythm of urinary 17-hydroxycorticosteroids during metyrapone-induced ACTH release in normal subjects.

The circadian rhythm of urinary 17-OHCS was studied in nine normal subjects before and after oral metyrapone administration (750 mg every 4 hrs over a period of 24 hrs). The test was carried out twice in each subject with a shift of 12 hrs in the time of first administration (0800-test and 2000-test). For data from serial measurements of steroid metabolites on urine collected at 2-h intervals, the least squares fit of a 24-h cosine curve allowed the demonstration of a rhythm both in control conditions and during the 48-h span following metyrapone administration. Circadian acrophases were substantially similar. Total urinary 17-OHCS output in the first 24-h day following metyrapone was higher in the 2000-test as compared with the 0800-test (P less than .001). Conversely, in the second 24-h day, higher values were obtained in the 0800-test (P less than .025). The combined 48-h exretion, however, was identical in the two groups. The results suggest a time-limited action of metyrapone upon the pituitary-adrenal axis, since the increased excretion of 17-OHCS seems essentially accounted for by an exaggerated impulsive phase of ACTH secretion during the early morning hours.

17-Hydroxycorticosteroids↗
PubMedDate not supplied

Circannual rhythmicities of cortisol levels in the peripheral plasma of healthy subjects.

Seasonal variations of endocrine function have been extensively studied both in rodents and in man. However, only few studies have attempted to concomitantly evaluate and compare circadian and circannual components by inferential rhythmometric procedures. We have examined [9] circadian profiles (single cosinor: P less than 0.01) of plasma cortisol obtained from samples drawn at 4-h intervals in healthy adult subjects of both sexes (71 males, 120 females, aged 20-54 years) along a 7-year span, from 1974 to 1980. All subjects were routine synchronized. Circulating cortisol was measured by a competitive protein-binding technique and expressed as microgram/dl; intra-assay coefficient of variation was always less than 5%. Both conventional and rhythmometric analysis were used to evaluate seasonal differences of mesor, amplitude and acrophase. The population-mean cosinor analyses revealed statistically significant differences as a function of the time of the year in both the circadian amplitude and acrophase. Examining data year by year revealed in 5 out of 7 annual cycles an apparent tendency to a delayed acrophase and to a reduced amplitude with advancing months towards winter. No significant changes in mesor values were found. Further fitting to a 365.25-day cosine curve of circadian parameters available for different months of an 'average' year yielded significant circannual rhythmicity for acrophase and amplitude; crest-value resulted in spring and autumn, respectively. Our data extend previous observations and are consistent with the existence of circannual variations in plasma cortisol levels in the human. In Italian people, cortisol secretion is conceivably higher in cold months; seasonal changes, on the other hand, appear to be of minor entity of at least as inferred by transverse sampling on a relatively large population. Effects of lighting regimen and of other climatological variables upon the adrenal cycle have to be considered.

Adult↗
PubMedDate not supplied

[Evaluation of renal function during orthotopic liver transplantation].

BACKGROUND: Orthotopic liver transplantation (OLI) is a recognised means of therapy for endstage liver failure (ESLF). Both the preoperative alterations of renal function, closely correlated with the ESLF, and the frequent and abrupt changes of circulating blood volumes occurring during the various phases of OLT are able to significantly alter renal function during the perioperative period. METHODS: In order to define the specific changes of renal function during the various phases of OLT, six postnecrotic cirrhotic patients undergoing their first OLT entered a prospective study protocol. All the patients had standard and anesthetic techniques including the venovenous bypass (VVBP) during the anhepatic phase. At standard intervals (baseline, during hepatic dissection, during the anhepatic phase, following reperfusion, at the end of surgery) together with complete hemodynamic and metabolic profiles, arterial blood and urine samples were obtained to determine electrolytes and creatinine concentrations, blood levels of atrial natriuretic factor, aldosterone and renin activity. Using standard formulas creatinine clearance (Ccreat) and Na absolute and fractional excretions (FeNa%) were calculated. RESULTS: Major changes in the hemodynamic profile occurred during the anhepatic phase in spite of the use of the VVBP (reduced cardiac index, reduced pulmonary wedge pressure, increased systemic vascular resistances). Concomitantly a significant decrease in Ccreat (-67%) and in urinary output, was present while aldosterone and renin activity increased. The changes in Ccreat persisted at the end of surgery in spite of the optimal hemodynamic profile. Aldosterone and renin activity returned to values close to baseline at the end of surgery. CONCLUSIONS: From these data it is possible to conclude that renal function markedly deteriorates during OLT and it has to be considered at increased risk in the immediate postoperative period. The use of VVBP does not seem to prevent the intraoperative renal impairment.

Adult↗