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C Decristoforo

Publications and source records attributed to C Decristoforo.

10 recordsLinked to original sources
PubMed1998

Myocardial fatty acid metabolism during acute cardiac allograft rejection.

Fatty acids are promptly taken up, metabolised and eliminated by healthy cardiomyocytes. Cardiomyopathy, coronary heart disease and chronic rejection are known to be associated with an impaired fatty acid metabolism. It was the aim of this study to investigate fatty acid metabolism in a rat heart transplant model and to correlate scintigraphic findings with histological changes. After right-side nephrectomy of Lewis recipients Brown Norway cardiac allografts were anastomosed to the renal vessels. Animals were given no immunosuppression. The metabolism of carrier-free 17-123 jodo-heptadecanoic acid (123J-HDA) with a specific activity of > 2 x 10(17) Bq/ml was scintigraphically measured between days 1 and 11. An increase in the grade of rejection was observed over time. Fifty-six frames of 30 s duration each were recorded. For the region of interest (native heart, transplanted heart, left kidney) frames 10-56 were superimposed, time-activity curves generated and monoexponentially fitted. Furthermore, elimination half-life and intercepts were calculated. Following scintigraphic evaluation the animals were killed and graft as well as native hearts excised for histological examination. The uptake of the tracer identified severe grades of rejection. Elimination half-life of the tracer was twice as long from hearts with mild rejection and more than 14 times as long in severe rejection compared with no rejection. Elimination half-life and amplitude did not permit discrimination between grades 1, 2 and 3 a, but significantly decreased in groups 3 b and 4. This method therefore seems to be a valuable tool for the noninvasive detection of severe acute cardiac allograft rejection. Since fatty acid metabolism is clearly stress-dependent it remains to be seen whether this method allows detection of earlier rejection in loaded hearts.

Animals↗
PubMed1998

Determination of Sn(II) in technetium cold kits by voltammetry at the hanging mercury drop electrode (HMDE) and relevant radiopharmaceutical applications.

A novel approach for the determination of the stannous content in cold kits for labelling with 99mTc is described. The method is based on differential pulse polarography on the hanging mercury drop electrode in a methanol/water/perchloric acid mixture and is easy to perform. Examples for the determination of tin(II) in fractionated technetium cold kits are shown. The stability of tin(II) in solution was mainly dependent on the storage temperature and the kit composition. The low stability of stannous ions under certain conditions was shown to be the main reason for low radiochemical purity. Limits and dangers of fractionating kits are discussed and related to content and instability of tin(II).

Electrochemistry↗
PubMed1997

Brain perfusion scintigraphy with 99mTc-HMPAO or 99mTc-ECD and 123I-beta-CIT single-photon emission tomography in dementia of the Alzheimer-type and diffuse Lewy body disease.

Dementia of the Alzheimer-type (DAT) is characterized by progressive cognitive decline, variably combined with frontal lobe release signs, parkinsonian symptoms and myoclonus. The features of diffuse Lewy body disease (DLBD), the second most common cause of degenerative dementia, include progressive cognitive deterioration, often associated with levodopa-responsive parkinsonism, fluctuations of cognitive and motor functions, psychotic symptoms (visual and auditory hallucinations, depression), hypersensitivity to neuroleptics and orthostatic hypotension. A recent report suggests that positron emission tomography studies in patients with degenerative dementia may be useful in the differential diagnosis of DAT and DLBD. However, the diagnostic role of single-photon emission tomography (SPET) studies remains to be established. The aim of this study was therefore to evaluate regional cerebral perfusion [with either technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) or 99mTc-ethyl cysteinate dimer (99mTc-ECD) SPET] and striatal dopamine transporter density [using iodine-123 2 beta-carboxymethoxy-3 beta-[4-iodophenyl]tropane (123I-beta-CIT) SPET] in patients with DAT and DLBD. Six patients with probable DAT and seven patients with probable DLBD were studied. Blinded qualitative assessment by four independent raters of 99mTc-HMPAO or 99mTc-ECD SPET studies revealed bilateral temporal and/or parietal hypoperfusion in all DAT patients. There was additional frontal hypoperfusion in two patients and occipital hypoperfusion in one patient. In the DLBD group, regional cerebral perfusion had a different pattern. In addition to temporoparietal hypoperfusion there was occipital hypoperfusion resembling a horseshoe defect in six of seven patients. In the DAT group, the mean 3-h striatal/cerebellar ratio of 123I-beta-CIT binding was 2.5 +/- 0.4, with an increase to 5.5 +/- 1.1 18 h after tracer injection. In comparison, in the DLBD patients the mean 3-h striatal/cerebellar ratio of 123I-beta-CIT binding was significantly reduced to 1.7 +/- 0.3, with a modest increase to 2.1 +/- 0.4 18 h after tracer injection (P < 0.05, Scheffe test, ANOVA). These results suggest that 99mTc-HMPAO or 99mTc-ECD and 123I-beta-CIT SPET may contribute to the differential diagnosis between DAT and DLBD, showing different perfusion patterns and more severe impairment of dopamine transporter function in DLBD than in DAT.

Aged↗
PubMed1997

The use of electronic autoradiography in radiopharmacy.

The use of Microchannel Plate Analysers (Instant Imager, Canberra Packard), the so called Electronic Autoradiography, in Radiopharmacy is described. The system can be used for quality control of radiopharmaceuticals as well as for scientific research purposes. Quantitative analysis of 2-dimensional radioactive samples of all radionuclides used in Nuclear Medicine (especially 99mTc) can be performed in a very short time with little effort. Advantages and limitations for radiopharmaceutical work are described.

Autoradiography↗
PubMed1997

Evaluation of immunological mechanisms mediating thyroid-associated ophthalmopathy by radionuclide imaging using the somatostatin analog 111In-octreotide.

Thyroid associated ophthalmopathy (TAO) is a disorder involving the soft tissues and extraocular muscles of the orbit seen mainly in cases of Graves' disease. Although an immunogenic pathogenesis has been proposed, the actual mechanisms of the in vivo retrobulbar involvement are not well defined. The recent introduction of the 111In-labeled somatostatin analog, octreotide, which can bind in vivo to the cell membrane of activated lymphocytes expressing somatostatin receptors, has provided a new investigational tool for diseases with a presumed immunological background. Based on this property, octreotide scans can be expected to be positive in cases of immunological disease showing tracer accumulation within affected sites. The aim of this study was to evaluate the utility of scintigraphic imaging with octreotide of the retrobulbar space in cases of TAO, including sequential studies of patients undergoing immunosuppressive therapy. We studied a series of 51 patients who had Graves' disease with varying degrees of TAO. Nine patients had received immunosuppressive therapy. The degree of orbital inflammation was classified according to the clinical activity score of Mourits. Both planar and tomographic imaging of the orbit were carried out using 111 MBq of the 111In-labeled octreotide (OctreoScan) 2 h after tracer injection. A significant tracer accumulation in the retrobulbar space was seen in all 20 patients with a high activity score, in 8 of 16 cases with a negative score, and in 11 of 20 cases with an intermediate Mourits' score. In cases of persistent eye disease in spite of immunosuppressive therapy, the octreotide scan remained positive. Successful therapy either with prednisolone, external radiation, or i.v. immunoglobulins showed a significant diminution of tracer uptake after finishing the therapeutic regime. Three-dimensional reconstruction of the images also revealed a significant tracer accumulation in the areas of the lacrimal gland, the nasal region, and the pituitary. Controls cases (n = 30) showed no uptake in the orbital region. We conclude that 111In octreotide scintigraphy is an objective method that identifies patients with active inflammatory eye disease, i.e., having significant tracer uptake in the retrobulbar space. This uptake appears to reflect an immunological process, since immunosuppressive therapy will significantly decrease tracer accumulation.

Adult↗
PubMed1994

Technetium-99m human immunoglobulin scintigraphy in psoriatic arthropathy: first results.

Standard bone scintigraphy [using technetium-99m methylene diphosphonate (MDP)] is widely held to be the most sensitive method for the early detection of psoriatic arthropathy. Preliminary results of this study reveal that 99mTc human immunoglobulin (HIG) scintigraphy demonstrates a typical premature pattern of extradermal psoriatic disease in digits indicative of the early stage of psoriatic arthritis. This pattern was also found in a rare case of psoriatic arthropathy without skin lesions. 99mTc-HIG scintigraphy appears to reveal the initial inflammatory characteristics of later bone lesions. In the advanced stage of psoriatic arthritis, 99mTc-MDP and 99mTc-HIG scans were found to be equally sensitive in the detection of the affected joints. Thus 99mTc-HIG scintigraphy seems to be useful in the early detection of psoriatic arthropathy and also in advanced psoriatic arthritis, as well as for the detection of psoriatic arthropathy without skin lesions.

Arthritis, Psoriatic↗
PubMed1993

A simple two-strip method to determine the radiochemical purity of technetium-99m mercaptoacetyltriglycine.

Technetium-99m mercaptoacetyltriglycine (MAG3) has been used extensively as a renal function agent for several years. Radioimpurities in the MAG3 kit preparation are not only concentrated and excreted in the kidneys. Therefore proper quality control for renal studies is even more important to make possible a rapid and adequate interpretation of diagnostic studies. The standard method to determine the radiochemical purity is high-performance liquid chromatography (HPLC), which is time consuming and expensive. We set up a new simple thin-layer chromatography (TLC) method based on instant thin-layer silica gel strips as stationary phase for checking the main impurities, free pertechnetate and reduced hydrolysed 99mTc-colloid. Comparison of TLC and HPLC results showed no significant differences (t-test, P < 0.05); the correlation between the results obtained with the two methods in respect of the free pertechnetate content was excellent (r = 0.99913). The TLC method was also efficient in determining the percentage of 99mTc-colloid. The main impurity found in 37 routine preparations was free pertechnetate; the mean radiochemical purity was 97.95%. The time required to perform the analysis was less than 20 min. The new TLC system is a cheap, simple, fast, reliable and accurate method for the quality control of the MAG3 kit preparation, and is especially suitable for routine use.

Chromatography, High Pressure Liquid↗
PubMed1993

[Quality control of radiopharmaceuticals from the clinical aspect--a necessity?].

Radiopharmaceuticals are a special group of drugs since many are eventually prepared in the hospital and the nuclear medicine department is responsible for meeting quality criteria such as sterility, radionuclide, radiochemical and chemical purity of these drugs. We tested 266 preparations of 14 different radiopharmaceuticals from commercial kits for their radiochemical purity. Only four compounds showed deficiencies in labelling (anti-granulocyte MAb, HIG, HMPAO, MAG3, altogether 18 preparations). All of them were 99mTc-pharmaceuticals with a relatively low tin content of the kit. The reasons for the poor quality of these products could be found. This study shows the importance of a good quality control system (including other tests like sterility and environmental monitoring) to guarantee the safety and efficacy of radiopharmaceuticals prepared in the hospital.

Humans↗