Characterization of 5-HT transporter and receptor system in HeLaS3 cells by [(3)H]8-OH-DPAT and other serotonergic ligands.

[(3)H]8-OH-DPAT is a selective ligand for labeling 5-HT(1A) receptor sites. In competition binding experiments, we found that classic biogenic amine transporter inhibitors displaced [(3)H]8-OH-DPAT binding at its high-affinity binding sites in HeLaS3 cells. [(125)I]RTI-55 and [(3)H]paroxetine are known to specifically label amine transporter sites, and this was observed in our cells.

Discovery and characterization of [3H]8-OH-DPAT binding to HeLaS3 cells.

Some G protein-coupled receptors (GPCRs) have functional links to cancer biology, yet the manifestation of GPCRs in tumor types is little studied to date. Using a battery of radioligand binding assays, we sought to characterize GPCR recognition binding sites on HeLaS3 tumor cells. High levels of binding of the selective serotonin 5-HT(1A) receptor agonist [3H]8-OH-DPAT were observed in these cells.

Receptor binding activities of Chlorella on cysteinyl leukotriene CysLT, glutamate AMPA, ion channels, purinergic P 2Y, tachykinin NK2 receptors and adenosine transporter.

A Chlorella powder was tested in a total of 129 in vitro receptor binding assay systems. The results showed a potent inhibition of this powder on cysteinyl leukotriene CysLT2, and glutamate AMPA in a dose-concentration manner with IC(50) mean +/- SEM values of 20 +/- 4.5 microg/mL and 44 +/- 14 microg/mL, respectively.

Chlorella powder inhibits the activities of peptidase cathepsin S, PLA2, cyclooxygenase-2, thromboxane synthase, tyrosine phosphatases, tumor necrosis factor-alpha converting enzyme, calpain and kinases.

A Chlorella powder was tested in 118 in vitro enzyme assay systems. The powder showed potent inhibitions of peptidase cathepsin S, thromboxane A(2) synthase and cyclooxygenase-2 in a dose-concentration manner with IC(50)+/-standard error of the mean values of 3.46+/-0.

Catechol: A minimal scaffold for non-peptide peptidomimetics of the i + 1 and i + 2 positions of the beta-turn of somatostatin.

The design, synthesis, and evaluation of a series of catechol-based non-peptide peptidomimetics of the peptide hormone somatostatin have been achieved. These ligands comprise the simplest known non-peptide mimetics of the i + 1 and i + 2 positions of the somatostatin beta-turn. Incorporation of an additional side chain to include the i position of the beta-turn induces a selective 9-fold affinity enhancement at the sst2 receptor.

Design and synthesis of potent cystine-free cyclic hexapeptide agonists at the human urotensin receptor.

[structure: see text] Cyclic hexapeptides, incorporating a dipeptide unit in place of the disulfide bond found in urotensin, were prepared and screened at the human urotensin receptor. The bridging dipeptide unit was found to influence dramatically the affinity for the urotensin receptor. Alanyl-N-methylalanyl and alanylprolyl dipeptide bridges failed to afford active ligands, while the alanyl-alanyl unit yielded a ligand with submicromolar affinity for the urotensin receptor.

Replacement of Phe6, Phe7, and Phe11 of D-Trp8-somatostatin-14 with L-pyrazinylalanine. Predicted and observed effects on binding affinities at hSST2 and hSST4. An unexpected effect of the chirality of Trp8 on NMR spectra in methanol.

An alanine scan performed in the 1970s suggested that Phe(6) and Phe(11) are required for the binding of somatostatin (SRIF-14). Molecular modeling studies and replacement of Phe(6) and Phe(11) with a cystine bridge affording ligands with the retention of high biological activity, however, led to the alternate conclusion that Phe(6) and Phe(11) stabilize the bioactive conformation of SRIF-14. Subsequent studies revealed that Phe(11) shields Phe(6) in a "herringbone" arrangement.

Design, synthesis, and binding affinities of pyrrolinone-based somatostatin mimetics.

[structure: see text] Tetrapyrrolinone somatostatin (SRIF) mimetics (cf. 1), based on a heterochiral (D,L-mixed) pyrrolinone scaffold, were designed, synthesized, and evaluated for biological activity. The iterative synthetic sequence, incorporating the requisite functionalized coded and noncoded amino acid side chains, comprised a longest linear synthetic sequence of 23 steps.

Effects of chlorella on activities of protein tyrosine phosphatases, matrix metalloproteinases, caspases, cytokine release, B and T cell proliferations, and phorbol ester receptor binding.

A Chlorella powder was screened using 52 in vitro assay systems for enzyme activity, receptor binding, cellular cytokine release, and B and T cell proliferation. The screening revealed a very potent inhibition of human protein tyrosine phosphatase (PTP) activity of CD45 and PTP1C with 50% inhibitory concentration (IC(50)) values of 0.678 and 1.

Validation of a [3H]astemizole binding assay in HEK293 cells expressing HERG K+ channels.

A radioligand binding assay for the HERG (human ether-a-go-go-related gene) K(+) channel was developed to identify compounds which may have inhibitory activity and potential cardiotoxicity. Pharmacological characterization of the [(3)H]astemizole binding assay for HERG K(+) channels was performed using HERG-expressing HEK293 cells. The assay conditions employed yielded 90% specific binding using 10 microg/well of membrane protein with 1.