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S Spaventi

Publications and source records attributed to S Spaventi.

At least 37 records · Page 2Linked to original sources
PubMed1987

Nerve growth factor (NGF) induced differentiation of human neuroblastoma cells.

1. Nerve growth factor (NGF) induced differentiation of human neuroblastoma cell line. 2. The differentiated cells had a relatively high activity of adenylate cyclase and cyclic AMP phosphodiesterase, and a high intracellular level of cyclic AMP. 3. These cells synthesized a higher amount of met5-o-enkephalin than undifferentiated cells. 4. Undifferentiated cells bound less met5-enkephalin than differentiated cells. The maximum number of [3H]met5-enkephalin receptor sites per mg of membrane protein increased more in differentiated cells. 5. Previous observations taken together with our results suggests that increased intracellular levels of cyclic AMP after treatment with NGF induced differentiation of human neuroblastoma cells. Reversal of undifferentiated tumor cells into the differentiated changes the capacity of synthesis of met5-enkephalin and its interaction with receptors.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1984

Comparison of three deconvolution techniques in renography.

The importance of comparing various deconvolution techniques on real patient data lies in the fact that there are two different approaches to that problem. One, which prefers general-purpose techniques, using a matrix algorithm (MA) and fast-Fourier transformation (FFT) with various smoothings, filters, etc., and another which prefers deconvolution techniques which have been modified for the particular application. The modification may be in requiring well defined input or assuming a smooth result of deconvolution. The aim of this paper is to compare the general-purpose deconvolution technique mostly used in analyzing patient data in nuclear medicine using MA and FFT with deconvolution based on Laplace transformation (LT). They have been compared on real patient data renograms in 36 cases. The comparison shows that although the LT technique requires a well defined input and for that reason needs more computing time than the FFT and MA technique, it gives impulse response functions (IRF) without negative values or with negligible ones. Even more, using LT, which has been incorporated in a model of distribution and transport of tracer, without taking blood samples one can assess some other useful clinical parameters such as inverse value of clearance time constant (ICTC) and effective renal plasma flow (ERPF).

Humans↗
PubMed1984

A stochastic approach to tracer kinetics.

The single compartment well-mixed model ( SCWMM ) which has been used in almost all dynamic studies in nuclear medicine is, in fact , strictly accurate only in the case of a steady state obtained by means of constant administration of long-lived isotopes. That is the reason why SCWMM is not a good predictor of the behaviour of short-lived isotopes and why the distribution and transport of short- and long-lived isotopes in various situations has not yet been discussed in general terms. The aim of this paper is to do that by means of a more general stochastic approach. This more general approach takes into account the distribution and transport of tracer in the system, not requiring a hypothesis of good mixing and providing a possibility of making corrections due to decay in the case of short-lived isotopes studies.

Half-Life↗
PubMed1981

The uptake of radioiodinated 5 alpha-dihydrotestosterone by the prostate of intact and castrated rats.

Radioiodinated steroid 2 alpha-125I-dihydrotestosterone was prepared by direct labeling procedure and subsequently utilized in the distribution studies on Albino Wistar male rats. Maximum radioactivity in the prostate was found 3 h after the administration of the radiolabeled steroid to 24-h castrated animals (1.29%/g wet weight) and to intact rats (0.57%). The pretreatment of animals with dihydrotestosterone yielded lower uptake by the prostate (0.29%-0.30%), epididymis, and testis while it did not influence the distribution in other androgen-insensitive tissues. The carbon-iodine bond was proved to be intact in the radiopharmacon examined and in its metabolites when retained by the rat prostate. The reported results are in line with our previous investigations on in vitro binding of radioiodinated dihydrotestosterone to androgen receptors but indicate also little utility of the same label for the visualization of the prostate gland.

Animals↗
PubMed1981

Extended three-compartment model for the transport and distribution of Hippuran.

The distribution and transport of Hippuran is discussed. The activity leaving both kidneys has been calculated and compared with the bladder activity. It is shown that the Impulse Response Function of the ureter and bladder may be obtained by deconvolution, and data are presented relating to studies on one patient.

Biological Transport↗
PubMed1980

Primary hypertrophic osteoarthropathy (PHO) and changes in the joints. Clinical, X-ray, scintigraphic, arteriographic and histologic examination of 19 patients.

Nineteen patients with PHO with onset in childhood are presented. In 7 cases the syndrome was found in other family members too. In clinical, X-ray scintigraphic, arteriographic, and plethysmographic investigations, joint affection was found in 14 patients. Clubbing of the fingers and toes was seen in all the patients and a periosteal reaction was found in the long bones in 11 patients. Arteriography was carried out in 5 patients and showed hypervascularization and arteriovenous anastomoses in the clubbed fingers. The gas analysis of the arterial blood did not show any pathological changes. The histological finding showed poorly vascularized and oedematous periarticular tissue and ossification in the periosteal area, while in the synovial membrane, slight, nonspecific inflammatory changes were seen.

Adult↗
PubMed1980

The possibilities of scintigraphic visualization of surfactants in the lung of the rat.

Incorporation of radioactive iodine into the surfactant system of the rat lung has been studied. Specially prepared particles labelled by 125I-oleic acid or 131I-oleic acid were injected intravenously and the distribution of radioiodine in the body of the animals was observed at various time intervals by means of a gamma camera and a gamma counter. The results showing appreciable accumulation of isotope in the lungs and the surfactant phospholipids, constitute a basis for the development of a new scintigraphic method for studying metabolic functions and morphology of the lung.

Animals↗
PubMed1977

The use of 81mKr gas for the measurement of absolute regional lung ventilation.

In this paper a new method of using 81mKr for the measurement of specific absolute regional lung ventilation is described. Experimental data suitable for the calculation of quantitative regional ventilation are provided using an adequate respiratory system for 81mKr dosage and a scintillation gamma camera interfaced to a digital computer. A simple mathematical lung model for the inhalation of 81mKr is used to determine the specific ventilation and the parameters proportional to the ventilation for the whole lung and different lung regions in patients and in healthy subjects. The lung count rate for a given region correlated well with the ventilation of that region. Clinical examples are given and discussed.

Computers↗