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Biomedical subjects

G Roncari

Publications and source records attributed to G Roncari.

At least 37 records · Page 2Linked to original sources
PubMed1986

Pharmacokinetics of the new benzodiazepine antagonist Ro 15-1788 in man following intravenous and oral administration.

During clinical pharmacology studies with the benzodiazepine antagonist Ro 15-1788 the pharmacokinetic characteristics of high intravenous doses (20 and 40 mg) and of an oral dose (200 mg) were examined in six healthy male volunteers. Ro 15-1788 was rapidly and extensively distributed in the body with an apparent volume of distribution Vss of 1.06 l kg-1. Elimination occurred rapidly by hepatic metabolism and the high plasma clearance of 1.14 l min-1 resulted in a short elimination half-life of less than 1 h. No difference in the disposition parameters calculated from the data after the 20 and 40 mg doses was observed reflecting a dose-proportionality in the areas under plasma concentration-time curves and unchanged distribution characteristics. Because the blood/plasma distribution coefficient is close to unity the disposition parameters obtained from plasma concentrations are similar to the corresponding parameters with reference to blood. Following oral administration of 200 mg the drug is rapidly absorbed. Peak levels were reached after 20-90 min and were close to or even higher than the values after the 40 mg intravenous dose at the same time point. Due to the high hepatic extraction ratio the fraction reaching the systemic circulation unchanged was reduced to approximately 16% during the absorption step.

Absorption↗
PubMed1985

[Phase and amplitude images using Fourier analysis in radioisotopic angiography. Comparison with contrast angiography for studying regional changes in ventricular contraction].

Phase-amplitude images and phase distribution histograms, derived from a temporal Fourier analysis of equilibrium ecg-gated blood pool studies, were used to assess the overall wall motion synchronism and to detect regional wall motion abnormalities in 69 consecutive patients with suspected or documented coronary artery disease, in whom biplane contrast left ventriculography and coronary angiography were performed. Four regions were considered on the 15 degrees caudal left-anterior oblique view radionuclide image, in order to identify the 7 conventional angiographic left ventricular wall segments (as the American Heart Association Council of Cardiovascular Surgery). Regional abnormalities on the phase-amplitude images from the 15 degrees caudal left anterior oblique view scans were studied in order to identify local hypokinesis, akinesis or dyskinesis (in accord to definitions used for contrast cineangiography) relative to seven conventional left ventricular wall segments. Results of phase-amplitude image analysis were compared with those of contrast cineangiography. The parametric images showed overall sensitivity of 82% and 92% respectively towards biplane and monoplane (left anterior oblique) contrast cineangiography, with a high degree of specificity (97%). Most akinetic and dyskinetic segments were correctly identified. A significant phase delay (greater than or equal to 70 degrees) from mean value, always occurred in dyskinetic segments and generally related to the severity of the wall motion abnormality. Lower accuracy was observed for hypokinetic regions; sensitivity was lower for apical and antero-lateral segments.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

Calcitonin in chronic renal failure.

The pattern of circulating calcitonin (CT) has been studied in relation to other humoral factors (PTH, calcium, phosphate and magnesium) in patients with chronic renal failure on either conservative or dialysis treatment. The latter group was studied before and after dialysis. In both groups, in basal conditions there was a significant increase in the circulating levels of CT, PTH, phosphate and magnesium and a significant decrease in calcemia compared to control group values. Positive correlations were found between increased CT and PTH and between CT and phosphate in uremic patients on conservative medical treatment, but not in those on hemodialysis. In the hemodialyzed group, the postdialysis increase in calcemia was significantly correlated to an increase in calcitoninemia. These data would indicate that even in severe uremia parafollicular cells are still able to increase CT secretion in response to physiological stimuli.

Adult↗
PubMed1981

Clinical studies of bone metabolism using a simple model of calcium tracer kinetics.

Bone metabolism studies were performed in 44 subjects with and without bone disease using a calcium tracers kinetics model, the central feature of which is an expanding exchangeable calcium pool. In normal subjects the accretion rate and the exchangeable calcium pool ranged from 1.49 to 8.45 (mean 3.9 +/- 2.05) mg.d-1kg-1 and from 60 to 131 (mean 81.25 +/- 18.11) mg.kg-1, respectively. The patients with osteogenesis imperfecta. Pierre Marie's disease and one out of two cases of hypoparathyroidism had values which fell within the normal range. Both the accretion rate and the exchangeable calcium pool were significantly elevated in patients with Paget's disease and with hyperparathyroidism. Uremic patients with generalized bone lesions had accretion rates or both parameters elevated. As far as patients with successful renal transplant are concerned, the results suggest that this method is a very poor means for detecting bone disorders with only focal lesions. In contrast, the method can be very useful when persistent renal osteodystrophy or secondary hyperparathyroidism are suspected.

Adult↗
PubMed1981

[The association of lymph nodes scintigraphy with 99Tcm-sulfur-microcolloid and ultrasounds scan in stage diagnosis of lymphomas (author's transl)].

Thirty seven patients with lymphomatous disease were studied to detect abdominal lymph nodes involvement by means of lymph nodes scan with 99Tcm-sulfur-microcolloid, ultrasounds scans, lymphangiographies. Lymphangiography was considered as reference standard in patients which explorative laparotomy was not performed in. Isotopic method demonstrated high sensitivity, despite low specificity. Opposite results were obtained by ultrasounds. We concluded that isotopic abdominal lymph nodes scan is a clinically valuable test, if negative, while ultrasounds are, if positive. Both methods, specially if associated, proved quite useful in restaging after therapy, where important parameters are low risk and stress for the patients, easy execution, low costs.

Aged↗
PubMed1980

[Whole-body osseous scintigraphy and Ca++ kinetics in patients with renal transplants].

Bone scintigraphy with 99mTc-diophosphonate and a whole body scanner was performed on 18 subjects with good renal function who had received a kidney transplant more than six months previously. This demonstrated scintigraphyc abnormalities in 17 of the cases. The alterations were characterized in 44,5% of the cases by focal uptake of the tracer. Diffuse alterations were observed in 4 of the 18 cases studied (22%). In these patients increases of serum alkaline phosphatase and in PTH levels were present. Ca++ exchangeable pool values and accretion rate were normal in the subjects with focal lesions. In the cases where scintigraphy showed diffuse lesions both the above parameters were much increased.

Adolescent↗
PubMed1980

Description of a simple model for the study of bone calcium metabolism.

A simple model for the study of bone calcium metabolism is proposed. It describes the kinetics of a radioactive tracer in terms of an open single compartment system with an expanding volume for a finite period of time. In addition to the simplicity of the hypotheses introduced, the model is able to give a good description of the biological processes which regulate calcium kinetics. Moreover the functional parameters can be easily calculated, even just graphically. 15 normal subjects and 22 patients affected by various bone diseases were studied. The results were compared with those obtained by using the model proposed by Burkinshaw et al. and the method described by Reeve et al.

Body Fluid Compartments↗
PubMed1975

The renal plasma flow and glomerular filtration rate as estimated through double radiocompound renography.

In order to estimate the renal plasma flow and glomerular filtration rate during the course of renography, a method was developed using simultaneously 131I Hippuran and 169Yb DTPA. First results obtained in a survey of approximately 200 patients are encouraging. The method permits an accurate evaluation of the renal function. In addition, by comparing the clearance rate of the two radiocompounds one can also obtain some interesting diagnostic information which can contribute usefully to the interpretation of renographic tracings and/or gamma camera sequential images.

Acute Disease↗