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Summary The dopamine D4 receptor (D4R) is expressed in low density in various extrastriatal brain regions. This receptor subtype is discussed in relation to the pathophysiology and treatment of schizophrenia but to date no selective positron emission tomography (PET) ligand is available to study its distribution in vivo . The 7-azaindole derivative 3-{[4-(4-iodophenyl)piperazin-1-yl]-methyl}-1H-pyrrolo[2,3-b]pyridine (L-750,667) is a novel, high-affinity (K i=0.51nM) and selective D4R ligand. L-750,667 analogue 3-{[4-(4-[18F]fluorobenzyl)]piperazin-1-yl}methyl-1H-pyrrolo[2,3-b]-pyridine was prepared by reacting 3-(piperazin-1-yl)-methyl-1H-pyrrolo[2,3-b]pyridine with 4-[18F]fluorobenzaldehyde, which was labeled with no carrier added [18F]fluoride. The radiochemical yield of 3-{[4-(4-[18F]fluorobenzyl)]piperazin-1-yl}methyl-1H-pyrrolo[2,3-b]pyridine was 12.0 at end of synthesis (EOS), and the synthesis time was 73min. The labeled benzaldehydes may be useful precursors for the radiosyntheses of other complex radiotracers for PET.

A method for 103Pd “molecular plating” onto the surface of the copper rod is reported. The optimal composition of the plating bath was: palladium chloride 2 g/l, ammonium hydroxide (28%) 150 ml/l, sodium hypophosphite 12 g/l, and ammonium chloride 37 g/l. The whole procedure of 103Pd “molecular plating” will last 50 minutes at 40 °C. This article provides valuable experience for the preparation of 103Pd seeds.

Hepatocellular carcinoma (HCC) is one of the most common malignancies in China. Direct intratumoral injection of nonremovable radioactive material has been widely studied because it could deliver high doses of radiation to target sites and minimize radiation leakage to non-target organs or tissues. Thirty nude mice bearing SMMC 7721 human liver carcinoma were used for the biodistribution study after intratumoral injection of [Re-188]rhenium sulfide suspension or sodium [Re-188]perrhenate solution. Another 30 tumor-bearing mice were divided into six groups, four groups of which were treated with a 0.1 ml [Re-188]rhenium sulfide suspension at doses of 3.7, 7.4, 18.5, 29.6 MBq by a single intratumoral injection. For control studies, to study the tumor inhibiting ratio, the remaining two groups were injected with nonradioactive rhenium sulfide suspension and Hanks' balanced salt solution, respectively. The injections were repeated 6 days later, The retention percentages of radioactivity (%ID) in tumors injected with [Re-188]rhenium sulfide suspension were 90.96 + 6.63%, 86.09 +/- 22.58% and 87.62 +/- 13.97% at 1, 24 and 48 h, respectively. Tumor inhibition ratios are as high as 89% when the outer space of tumor (0.5-0.6 cm from center) received about 507.6 Gy doses. Intratumoral injection of [Re-188]rhenium sulfide suspension results in high tumor retention indicating this approach has strong potential for the treatment of hepatic carcinoma, NUCL MED BIOL 27;4:347-352, 2000. (C) 2000 Elsevier Science Inc. All rights reserved.

[Re-188]Rhenium sulfide suspension was prepared by the reaction of Na2S2O3 and KReO4 containing (NaReO4)-Re-188 in acid solution and assessed for its applicability in tumor treatment by the techniques of radioisotope interventional therapy. The reaction conditions such as the concentration ratio of Na2S2O3, to KReO4, heating time, ultrasonic time were optimized. The radiochemical yield of [Re-188]Rhenium sulfide suspension is more than 96% and in vitro stability studies demonstrated that more than 99% of the 188Re remained in sulfide form over a 72hrs period. The main particle size after various ultrasonic times is 1-5 mu m. [Re-188]Rhenium sulfide suspension was injected into tumors and the tumor-bearing mice were killed after some time to determine the retention of Re-188 in tumor and the leakage to different organs by gamma counter. The mean retention percentages of Re-188 in tumors were 83.08 +/- 13.71%, 83.92 +/- 9.79%, 80.23 +/- 3.82% and 78.75 +/- 3.02% at Ih, 24, 48 and 72hrs respectively. After 72hrs the highest activity outside the tumors was in the liver, spleen and the kidneys. Our preliminary results indicated that [Re-188]Rhenium sulfide suspension may be an effective radiopharmaceutical for tumor treatment by the techniques of radioisotope interventional therapy.

A separation procedure of trace platinum from large amounts of mercury and other interfering elements is described. After irradiation, the HgO target was dissolved in concentrated HCl solution. The thallium fraction was removed by solvent extraction with ether. In the aqueous phase after extraction the radioisotope of platinum produced by irradiation was precipitated as (NH4)2PtCl6 by adding a saturated solution of NH4Cl in the presence of H2PtCl6·6H2O as stable carrier. The decontamination factor of mercury, gold and thallium and the recovery of platinum in the process of separation are satisfactory.

A method for 103Pd “molecular plating” onto the surface of a silver rod is reported. The optimal composition of the plating bath is as follows: palladium chloride 0.1 mol/l, formaldehyde 2 mol/l, nitric acid 1 mol/l, and formic acid 0.4 mol/l. The 103Pd molecular plating procedure will last 25 min at 30°C. This article provides a valuable experience for the preparation of 103Pd brachytherapy seed.

The contents of 15 trace elements in the sera of 30 liver cancer patients and 30 healthy adults were assayed by ICP-AES method. The data obtained were analysed by routine statistical tests, multi-variate discrimination analysis, multi-variate stepwise regression analysis and non-linear mapping algorithm. The results showed that the contents of copper, vanadium, cadmium, stannum, cobalt, nickel in liver cancer patients were significantly higher than those in healthy adults. The serum trace element spectrum of liver cancer patients was different from that of healthy adults. Hence, the liver cancer patients could be differentiated from healthy adults by serum trace element spectrum.

Intralesional therapy has been shown to be an effective treatment for tumors. In this study, the suitability of [Re-188]rhenium sulfide suspension for tumor treatment following intra-tumor injection was evaluated. The [Re-188]rhenium sulfide suspension was radiolabeled with Re-188 with a radiochemical yield of more than 96%. In vitro stability studies revealed that more than 99% of the Re-188 remained in sulfide form over a 3-day period. After ultrasonication for 5 or 10 min, the main particle size was 1-5 mu m. Two [Re-188]rhenium sulfide suspensions ultrasonicated for 5 and 10 min, respectively, were injected into separate group of tumor-bearing mice that were killed after specified times to compare the retention of Re-188 in tumors and the leakage to different organs by periods and organs removed to gamma counting. The mean retention percentages of Re-188 in tumors injected with suspension ultrasonicated for 5 (or 10) min were as follows: 1 h, 90.5 +/- 7.7% (83.1 +/- 13.7%); 24 h, 92.2 +/- 8.6% (83.9 +/- 9.8%); 48 h, 88.3 +/- 10.9% (80.2 +/- 3.8%); and 72 h, 91.5 +/- 7.6% (78.8 +/- 3.0%). Tumor-inhibiting ratio was 96.5%. These results demonstrated that [Re-188]rhenium sulfide suspension is an effective radiopharmaceutical for tumor treatment by intralesional therapy. (C) 1999 Elsevier Science Inc. All rights reserved.