In vitro evaluation of tc-99m radiopharmaceuticals for gastric emptying studies.

OBJECTIVE: Gastrointestinal motility and functional motility disorders causing either delayed or accelerated gastric emptying (GE) may result in similar symptoms including nausea, vomiting, early satiety, fullness, bloating, and abdominal discomfort or pain. Hence, it is important to evaluate patients for both rapid and delayed GE in the same test. The gold standard technique to measure GE is scintigraphy by radiolabeled test meals. The aim of this study was to test alternative Tc-99m agents to label eggs as the solid meal and compare to Tc-99m sulfur colloid (SC) for gastric emptying studies. METHODS: In search of alternative agents for gastric emptying studies, we mixed and fried eggs with four different particulate compounds (Tc-99m labeled SC, tin colloid, nanocolloid and MAA), as well as with free pertechnetate and Tc-99m DTPA. We then measured the stability of these compounds in simulated gastric juice. RESULTS: Our experiments demonstrated that in addition to Tc-99m sulfur colloid;Tc-99m MAA, Tc-99m nanocolloid and Tc-99m tin colloid also appear to make stable complexes with eggs in acidic environment. CONCLUSION: Therefore, these agents may be used for gastric emptying studies which could be more practical in routine conditions. CONFLICT OF INTEREST: None declared.

99mTc-HMPAO labelling inhibits cell motility and cell proliferation and induces apoptosis of NC-NC cells.

(99m)Tc-hexamethyl-propylenamine-oxime ((99m)Tc-HMPAO)-labelled leukocytes have been used in standard diagnostic procedures for the detection of infection and inflammation. Although some investigators have already pointed out that labelling of leukocytes with (99m)Tc-HMPAO has detrimental effects on the cells, still very little is known regarding the effects of ionizing radiation on lymphocyte function. The effects of (99m)Tc-HMPAO-labelling on lymphocyte adhesion, proliferation, mitotic index, migration and apoptosis were evaluated. The lymphoblastoid cell line NC-NC was used as the lymphocyte population. (99m)Tc-HMPAO-labelling decreased cell adhesion, proliferation, mitotic index and motility, whereas it induced apoptosis and cell-cycle arrest. The rate of decrease in cell proliferation was up to 70% (P<0.001) by day 4 after labelling. (99m)Tc-HMPAO-labelling led a 35% decrease (P<0.001) in adhesion ability of the cells on fibronectin at 16h. Using the Boyden chamber motility assay, it was shown that both spontaneous and monocyte chemotactic protein (MCP-1)-induced lymphocyte motility were strongly reduced by (99m)Tc-HMPAO-labelling. The decrease in motility was approximately five-fold (P<0.05). In addition, a 12-fold increase (P<0.05) was observed in apoptosis of the (99m)Tc-HMPAO-treated cells compared with control cells. Besides, it was shown that cell-cycle arrest was induced starting from the 3rd day after treatment with (99m)Tc-HMPAO. Our observations indicate that (99m)Tc-HMPAO-labelling has damaging effects on lymphocyte function including cell adhesion, proliferation, mitotic index, motility and cell cycle under in vitro conditions.

Platelet scintigraphy results of heparin versus streptokinase treatment in acute deep vein thrombosis.

OBJECTIVE: The aim of the study was to document the therapeutic effects and primary recanalization ratios of either streptokinase or heparin in the therapeutic process of deep vein thrombosis (DVT). The results are obtained with the help of platelet scintigraphy. DESIGN: The investigation was planned as a randomized, controlled and prospective study, including 20 patients within two groups. Group I contained 10 patients undergoing IV infusion therapy of unfractionated heparin while Group II contained 10 patients undergoing thrombolytic therapy using streptokinase. After 8 weeks, scintigraphies using Tc-99m HMPAO-labeled thrombocytes were made, and interpreted by two blinded nuclear medicine physicians. The results are compared using Mann-Whitney U- and chi2-tests. RESULTS: No complication leading to interruption of therapy took place. Significantly smaller pathologic thrombocyte accumulations were detected in the streptokinase group. The difference was statistically significant (p = 0.019). CONCLUSION: Although a general clinical improvement had been observed in all patients, the scintigraphic investigation showed that the thrombolytic therapy maintained a better deep vein luminous patency.