Yttrium-86-labelled human serum albumin microspheres: relation of surface structure with in vivo stability.

Introduction: Radiolabelled particles are an attractive tool in the therapy of malignancies of the liver. We consider particles manufactured from denatured human serum albumin (HSA) as useful carriers of therapeutic radionuclides. Covalent attachment of suitable chelators onto the surface of the spheres promises an easy access to radiolabelled HSA microspheres.

3-O-methyl-6-18F-fluoro-L-dopa, a new tumor imaging agent: investigation of transport mechanism in vitro.

Unlabelled: (18)F-Labeled amino acids represent a promising class of imaging agents in tumors, particularly brain tumors. However, the determination of their potential to image peripheral tumors, possibly depending on individual transport characteristics, still remains an area of investigation. The present study investigated the transport mechanism for 3-O-methyl-6-(18)F-fluoro-L-dopa (OMFD), a novel (18)F-labeled phenylalanine derivative, into tumor cells.

Autoradiographic imaging of the serotonin transporter in the brain of rats and pigs using S-([18F]fluoromethyl)-(+)-McN5652.

The [18F]fluoromethyl analogue of (+)-McN5652 ([18F]FMe-McN) has recently been developed as a radioligand for imaging the neuronal serotonin transporter (SERT) with positron emission tomography (PET). We describe here the autoradiographic evaluation of [18F]FMe-McN in the brain of rats and pigs. Autoradiographic studies of [18F]FMe-McN performed on rat and pig brain in vitro showed a high accumulation of radioactivity in the regions rich in SERT, such as amygdala, hypothalamus, superficial gray layer of the superior colliculus, various nuclei of thalamus and substantia nigra.

Positron emission tomography imaging of the serotonin transporter in the pig brain using [11C](+)-McN5652 and S-([18F]fluoromethyl)-(+)-McN5652.

S-([(18)F]fluoromethyl)-(+)-McN5652 ([(18)F](+)-FMe-McN5652) has recently been synthesized as a new potential radiotracer for positron emission tomography (PET) imaging of the 5-HT transporter. It is an analog of [(11)C](+)McN5652, which has been used in clinical PET studies for 5-HT transporter imaging. This article describes the comparison of these two radiotracers in pigs with respect to their in vivo binding characteristics.

Effect of hypoxia/hypercapnia on metabolism of 6-[(18)F]fluoro-L-DOPA in newborn piglets.

There is evidence that the dopaminergic system is sensitive to altered p(O(2)) in the immature brain. However, the respective enzyme activities have not been measured in the living neonatal brain together with brain oxidative metabolism. Therefore 18F-labelled 6-fluoro-L-3,4-dihydroxyphenylalanine (FDOPA) together with positron emission tomography (PET) was used to estimate the activity of the aromatic amino acid decarboxylase (AADC) in the brain of fifteen newborn piglets (2-5 days old).

Development of technetium-99m-based CNS receptor ligands: have there been any advances?

By virtue of its ideal nuclear physical characteristics for routine nuclear medicine diagnostics and its ready availability, technetium-99m is of outstanding interest in the development of novel radiopharmaceuticals. The potential for the development of 99mTc-based radioligands for the study the receptor function in the central nervous system (CNS) is also well recognised despite the difficulties to be overcome. A fundamental challenge is the pharmacologically acceptable integration of the transition metal technetium, with its specific coordination chemistry, into the molecular entity of CNS receptor ligands.

A novel technetium-99m radioligand for the 5-HT(1A) receptor derived from desmethyl-WAY-100635 (DWAY).

This paper reports the synthesis, biological evaluation and in vitro autoradiography of a new technetium-99m radioligand with high affinity for the 5-HT(1A) receptor. The neutral complex combines an N(2)S(2) diamine dithiol (DADT) ligand as complexing moiety for oxotechnetium(V) and a 2-(1-piperazino)phenol via a 6-carbon alkyl chain, derived from desmethyl-WAY 100635 (DWAY). The complex displays an IC(50) value for the 5-HT(1A) receptor of 1.

Biodistribution and catabolism of (18)F-labeled neurotensin(8-13) analogs.

4-([(18)F]fluoro)benzoyl-neurotensin(8-13) ((18)FB-Arg(8)-Arg(9)-Pro(10)-Tyr(11)- Ile(12)-Leu(13)-OH, 1) and two analogs stabilized in one and two positions ((18)FB-Arg(8)psi(CH(2)NH)Arg(9)-Pro(10)-Tyr(11)- Ile(12)-Leu(13)-OH, 2, (18)FB-Arg(8)psi(CH(2)NH)Arg(9)-Pro(10)-Tyr(11)-Tle(12)-Leu(13)-OH, 3) were synthesized in a radiochemical yield of 25-36% and a specific activity of 5-15 GBq/mmol. The peptides were evaluated in vitro and in vivo for their potential to image tumors overexpressing neurotensin receptor 1 (NTR1) by positron emission tomography (PET). All analogs exhibited in vitro binding affinity in the low nanomolar range to NTR1-expressing human tumors, measured by quantitative receptor autoradiography, HT-29 and WiDr cells, and to sections of tumors derived from these cell lines in mice.