Meretrix lusoria--a natural biocomposite material: in situ analysis of hierarchical fabrication and micro-hardness.

The ultrastructure of clam (Meretrix lusoria) was investigated by means of scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction analyzer (XRD) combining with in situ texture decalcified technique and the micro-hardness of clam was determined, in order to understand the spatial relationship between the mineral phase and organic matrix and further explain the correlation between the property and structure. The results showed that hierarchical fabrication is the major structure character of this mollusc shell. There is specific braided structure forming from domains composed of needle-like structure made up of the single crystal of aragonite.

A positron emission tomography radioligand for the in vivo labeling of metabotropic glutamate 1 receptor: (3-ethyl-2-[11C]methyl-6-quinolinyl)(cis- 4-methoxycyclohexyl)methanone.

A selective metabotropic glutamate 1 receptor (mGlu1) antagonist was labeled with the positron-emitting radioisotope carbon-11 and evaluated in ex vivo biodistribution studies and micro-positron emission tomography (micro-PET) imaging experiments in rats. Results from animal experiments demonstrate that the radioligand [11C]2 is the first PET tracer capable of labeling the rat mGlu1 receptor in vivo.

Epibatidine analogues as selective ligands for the alpha(x)beta2-containing subtypes of nicotinic acetylcholine receptors.

A series of epibatidine analogues was synthesized and characterized in vitro. These compounds are high affinity ligands for the nicotinic acetylcholine receptors (nAChR). They display binding selectivity for the alpha(x)beta2 subtypes of nAChRs over the alpha(x)beta4 subtypes, and especially for the alpha4beta2 and alpha2beta2 subtypes.

Fluorinated diaryl sulfides as serotonin transporter ligands: synthesis, structure-activity relationship study, and in vivo evaluation of fluorine-18-labeled compounds as PET imaging agents.

A series of new, fluorine-containing substituted diphenyl sulfides was synthesized to serve as candidate ligands for positron emission tomography (PET) imaging of the serotonin transporter (SERT) and to further probe the structure-activity relationship (SAR) of this class of compounds. Candidate compounds were assayed for their affinities to the monoamine transporters (SERT, norepinephrine transporter (NET), and dopamine transporter (DAT)) in competitive binding experiments in vitro using cloned human transporters. From these in vitro assays, four compounds (7c-f) were chosen for further evaluation.

The new PET imaging agent [11C]AFE is a selective serotonin transporter ligand with fast brain uptake kinetics.

A new positron emission tomography (PET) radioligand for the serotonin transporter (SERT), [(11)C]2-[2-[[(dimethylamino)methyl]phenyl]thio]-5-(2-fluoroethyl)phenylamine ([(11)C]AFE, 12), was synthesized and evaluated in vivo in rats and baboons. [(11)C]AFE (12) was prepared from its monomethylamino precursor 11 by reaction with high specific activity [(11)C]methyl triflate. Radiochemical yield was 32+/-17% based on [(11)C]methyl triflate (n=6) and specific activity was 1670+/-864 Ci/mmol at end of synthesis (EOS, n=6).

A PET imaging agent with fast kinetics: synthesis and in vivo evaluation of the serotonin transporter ligand [11C]2-[2-dimethylaminomethylphenylthio)]-5-fluorophenylamine ([11C]AFA).

A new serotonin transporter (SERT) ligand, [11C]2-[2-(dimethylaminomethylphenylthio)]-5-fluorophenylamine (10, [11C]AFA), was synthesized and evaluated as a candidate PET radioligand in pharmacological and pharmacokinetic studies. As a PET radioligand, AFA (8) can be labeled with either C-11 or F-18. In vitro, AFA displayed high affinity for SERT (Ki 1.

A new positron emission tomography imaging agent for the serotonin transporter: synthesis, pharmacological characterization, and kinetic analysis of [11C]2-[2-(dimethylaminomethyl)phenylthio]-5-fluoromethylphenylamine ([11C]AFM).

The synthesis, radiolabeling, and in vitro and in vivo evaluation of a new positron emission tomography (PET) radioligand for the serotonin transporter (SERT), [(11)C]2-[2-(dimethylaminomethyl)phenylthio]-5-fluoromethylphenylamine ([(11)C]AFM) is reported. AFM was prepared from 4-chloro-3-nitrobenzyl acetate and thiosalicylic acid in a five-step synthetic sequence. In binding studies in vitro with cloned human transporters, AFM displayed high binding affinity (Ki 1.

Synthesis and pharmacological characterization of a new PET ligand for the serotonin transporter: [11C]5-bromo-2-[2-(dimethylaminomethylphenylsulfanyl)]phenylamine ([11C]DAPA).

A new PET radioligand for the serotonin transporter (SERT), [11C]-5-bromo-2-[2-(dimethylaminomethylphenylsulfanyl)]phenylamine ([11C]DAPA (10), was synthesized and evaluated in vivo in rats and baboons. [11C]DAPA (10) was prepared from its monomethylamino precursor 8 by reaction with high specific activity [11C]methyl iodide. Radiochemical yield was 24 +/- 5% based on [11C]methyl iodide at end of bombardment (EOB, n = 10) and specific activity was 1,553 +/- 939 Ci/mmol at end of synthesis (EOS, n = 10).

Improving the labeling of S-acetyl NHS-MAG(3)-conjugated morpholino oligomers.

S-Acetyl MAG(3) (S-acetylmercaptoacetyltriglycine) has been used as a chelator for the (99m)Tc labeling of a variety of biomolecules. The objective of this study was to improve upon the labeling of morpholino (MORF), a DNA analogue, as a model biomolecule. A 15mer MORF with a primary amine was conjugated with NHS-MAG(3) in the usual manner, and the MORF-MAG(3) was purified over a P4 column as before.

In vitro and in vivo evaluation of a Technetium-99m-labeled cyclic RGD peptide as a specific marker of alpha(V)beta(3) integrin for tumor imaging.

Three amino acids residues, Arg-Gly-Asp (RGD), in vitronectin and fibronectin show affinity for alpha(V)beta(3) integrins expressed in vascular endothelial cells. That tumor growth can upregulate the expression of these integrins on tumor cells for invasion and metastasis and in tissue neovasculature suggests the potential of developing radiolabeled RGD peptides as antagonists of alpha(V)beta(3) integrins for broad spectrum tumor specific imaging. The polypeptide RGD-4C, which contains four cysteine residues for cyclization, has shown preferential localization on integrins at sites of tumor angiogenesis.