The synthesis and characterization of [(124)I]IMPY, a thioflavin-S derivative, in transgenic mouse models of Alzheimer's disease.

6-[(124)I]iodo-2-(4'-N,N-dimethylamino)-phenylimidazo[1,2-a]pyridine ([(124)I]IMPY) was synthesized and characterized as a positron-emitting probe to identify Alzheimer's disease in transgenic mouse models. A significant reduction in radioactivity retention in the hippocampus and frontal cortex by co-incubation with nonradioactive IMPY was observed. Highly specific retention of radioactivity in beta-amyloid-rich regions of brain sections was also noted. This study demonstrated that [(124)I]IMPY was a promising probe for the mouse model and may be useful for positron emission tomography to image beta-amyloid plaques in the human brain.

Radiolabelling of Lipiodol with generator-produced 188Re for hepatic tumor therapy.

In this study we prepared and analyzed the biodistribution of 188Re-labelled Lipiodol ([188Re]-Lipiodol) in rats after intrahepatic arterial injection. EDTB was synthesized by condensation of 1,2-benzenediamine and ethylenediaminetetraacetic acid (EDTA). The labelling efficiency of [188Re] Lipiodol was determined to be greater than 97% by ITLC developed with n-hexane. Following incubation of the [188Re] Lipiodol with an equal volume of serum at 37 degrees C for 48 h, ITLC indicated good in vitro stability. Approximately 7.4 MBq [188Re] Lipiodol was injected in each rat via the hepatic artery and samples of liver, spleen, muscle, lung, kidney, bone, whole blood and testis were obtained. [188Re] Lipiodol tissue concentrations showed that after 1 h intrahepatic injection most of the radiotracer was retained in the liver, and was eliminated slowly with a biological half-life of 33.5 h. Radioactvity levels in the lung, kidney and blood were moderate at 1 h, and declined rapidly over time. In the spleen, muscle, testis and bone, radiation levels were insignificant. These initial results indicate that -188Re- Lipiodol may be a potential radiopharmaceutical agent for the treatment of liver tumors.

Biodistribution of rhenium-188 Lipiodol infused via the hepatic artery of rats with hepatic tumours.

The purpose of this study was to analyse the biodistribution of rhenium-188 Lipiodol in rats with hepatic tumours following intrahepatic arterial injection to assess the potential of 188Re-Lipiodol as a radiopharmaceutical for the treatment of hepatic tumours in humans. Twelve male rats with hepatic tumours were killed at 1h, 24h and 48h after injection of approximately 7.4MBq of 188Re-Lipiodol via the hepatic artery. Samples of various organs were obtained and counted to calculate the tissue concentration. Radioactivity in the hepatic tumours was very high throughout this study, with a biological half-life of 122.9h. Radioactivity in the normal liver tissue was also high, but was significantly lower than in the tumour. The biological half-life in the normal liver tissue was 31.7h. The ratio of tumour concentration to the normal liver tissue concentration was 5.15 at 1h and rose to 7.7 at 24h and 10.84 at 48h. The level of radioactivity in the lung was high at 1h, and declined rapidly over time. The level of radioactivity in the kidney was moderate throughout the study. The radiation concentrations in muscle, spleen, testis, bone and whole blood were insignificant. We conclude that 188Re-Lipiodol should be considered as a potential radiopharmaceutical for the intra-arterial treatment of hepatic tumours.

Preparation and biodistribution of yttrium-90 Lipiodol in rats following hepatic arterial injection.

In this study, we labelled Lipiodol with yttrium-90 and analysed the biodistribution in rats after intrahepatic arterial injection. An RP-18 column (E. Merck) was used to separate 90Y from strontium-90. 90Y was retained on the column, which had been pretreated with yttrium-selective extraction reagent, di(2-ethylhexyl) phosphate, while 90Sr was washed out. A hexadentate nitrogen-donor chelating ligand N,N,N',N'-tetrakis(2-benzymidazolylmethyl)-1,2-ethanediamine (EDTB) was synthesized by condensation of 1,2-benzenediamine and ethylene diamine tetra-acetic acid (EDTA). Lipiodol was covalently conjugated with EDTB. The final product was obtained by eluting the retained 90Y from the RP-18 column with EDTB-Lipiodol. Sixteen male rats (Sprague-Dawley) were sacrificed at 1 h, 24 h, 48 h and 72 h (four rats at each time) after injection of approximately 0.1 mCi 90Y-Lipiodol via the hepatic artery. Samples of liver, spleen, muscle, lung, kidney, bone, whole blood and testis were obtained and counted to calculate the tissue concentrations. In addition, labelling efficiency and in vitro stability were determined by ITLC methods. We found that at 1 h after intrahepatic injection, most of the radiotracer was retained in the liver, but it was eliminated gradually over a few days. The radioactivity level in the lung was fair at 1 h and remained at roughly the same level throughout the study. Radioactivity in the kidney and spleen reached a relatively high level at 24 h, but declined rapidly.(ABSTRACT TRUNCATED AT 250 WORDS)