Brain-penetrating 2-aminobenzimidazole H(1)-antihistamines for the treatment of insomnia.

The benzimidazole core of the selective non-brain-penetrating H(1)-antihistamine mizolastine was used to identify a series of brain-penetrating H(1)-antihistamines for the potential treatment of insomnia. Using cassette PK studies, brain-penetrating H(1)-antihistamines were identified and in vivo efficacy was demonstrated in a rat EEG/EMG model. Further optimization focused on strategies to attenuate an identified hERG liability, leading to the discovery of 4i with a promising in vitro profile.

A novel water-soluble selective CRF1 receptor antagonist, NBI 35965, blunts stress-induced visceral hyperalgesia and colonic motor function in rats.

The stress response involves the activation of two corticotropin-releasing factor (CRF) receptor subtypes. We investigated the role of CRF1 in stress-related visceral responses. A novel water-soluble tricyclic CRF1 antagonist, NBI 35965 was developed that displayed a high affinity for CRF1 (Ki approximately 4 nM) while having no binding affinity to CRF2. This antagonist also inhibited the stimulation of cAMP induced by sauvagine in CRF1 transfected cells. NBI 35965 administered per orally (p.o.) in rats (1, 3, 10 or 30 mg/kg) inhibited dose-dependently [125I]sauvagine binding selectively at brain sites of CRF1 distribution as shown by ex vivo receptor autoradiography. At the highest doses, NBI 35965 completely prevented [125I]sauvagine labeling in the cortex. NBI 35965 (10 mg/kg) administered p.o. or subcutaneously (s.c.) 1 h before intravenous CRF completely blocked the 81% shortening of distal colonic transit time induced by CRF. NBI 35965 (20 mg/kg s.c.) significantly reduced the defecation in response to water avoidance stress but not that induced by s.c. carbachol. In adult male Long-Evans rats that had undergone maternal separation, acute water avoidance stress significantly increased the visceromotor response to colorectal distention (20-80 mmHg) by 42+/-19% compared with the response before stress. Stress-induced visceral hyperalgesia was abolished by NBI 35965 (20 mg/kg, s.c.). The data show that NBI 35965 is a novel water-soluble selective CRF1 antagonist with bioavailability to the brain upon peripheral administration and that CRF1 receptor signaling pathways are involved in water avoidance stress-induced hyperalgesia to colorectal distention and stimulation of colonic transit.

Sexual and reproductive health services and HIV testing: perspectives and experiences of women and men living with HIV and AIDS.

All over the world HIV has been stigmatised, making it difficult for people living with HIV to access testing, treatment, care and counselling or even to act on a diagnosis or get advice and treatment, for fear of being judged. Prejudice in society has also often been reflected and reproduced by health care providers. A human rights approach, which positively incorporates sexual and reproductive rights, rather than a restricted medical view, is therefore essential for the achievement of true partnerships between health care providers and service users. This paper is about the experiences of HIV positive women and men in sexual and reproductive health services and HIV testing. It provides guidance not only on how things could and should be done but also on how they should not be done. It outlines the sexual and reproductive rights positive people consider crucial and gives examples of how these are being violated. It presents perceptions and implications of HIV testing and how health services can support people after a positive diagnosis. It analyses the importance of confidentiality, continuity of care, knowledge and information, and the role of support groups and home-based care. It calls on sexual and reproductive health services to address issues of stigma and discrimination when offering and carrying out HIV testing and counselling, and in providing treatment, care and support.

Mechanism of corticotropin-releasing factor type I receptor regulation by nonpeptide antagonists.

Mechanisms of nonpeptide ligand action at family B G protein-coupled receptors are largely unexplored. Here, we evaluated corticotropin-releasing factor 1 (CRF(1)) receptor regulation by nonpeptide antagonists. The antagonist mechanism was investigated at the G protein-coupled (RG) and uncoupled (R) states of the receptor in membranes from Ltk(-) cells expressing the cloned human CRF(1) receptor. R was detected with the antagonist (125)I-astressin with 30 microM guanosine 5'-O-(3-thiotriphosphate present, and RG detected using (125)I-sauvagine. At the R state, nonpeptide antagonists antalarmin, NBI 27914, NBI 35965, and DMP-696 only partially inhibited (125)I-astressin binding (22-32% maximal inhibition). NBI 35965 accelerated (125)I-astressin dissociation and only partially increased the IC(50) value of unlabeled sauvagine, CRF, and urocortin for displacing (125)I-astressin binding (by 4.0-7.1-fold). Reciprocal effects at the R state were demonstrated using [(3)H]NBI 35965: agonist peptides only partially inhibited binding (by 13-40%) and accelerated [(3)H]NBI 35965 dissociation. These data are quantitatively consistent with nonpeptide antagonist and peptide ligand binding spatially distinct sites, with mutual, weak negative cooperativity (allosteric inhibition) between their binding. At the RG state the compounds near fully inhibited (125)I-sauvagine binding at low radioligand concentrations (79-94 pM). NBI 35965 did not completely inhibit (125)I-sauvagine binding at high radioligand concentrations (82 +/- 1%, 1.3-2.1 nM) and slowed dissociation of (125)I-sauvagine and (125)I-CRF. The antagonist effect at RG is consistent with either strong allosteric inhibition or competitive inhibition at one of the peptide agonist binding sites. These findings demonstrate a novel effect of R-G interaction on the inhibitory activity of nonpeptide antagonists: Although the compounds are weak inhibitors of peptide binding to the R state, they strongly inhibit peptide agonist binding to RG. Strong inhibition at RG explains the antagonist properties of the compounds.

Ligand affinity for amino-terminal and juxtamembrane domains of the corticotropin releasing factor type I receptor: regulation by G-protein and nonpeptide antagonists.

Peptide ligands bind the CRF(1) receptor by a two-domain mechanism: the ligand's carboxyl-terminal portion binds the receptor's extracellular N-terminal domain (N-domain) and the ligand's amino-terminal portion binds the receptor's juxtamembrane domain (J-domain). Little quantitative information is available regarding this mechanism. Specifically, the microaffinity of the two interactions and their contribution to overall ligand affinity are largely undetermined. Here we measured ligand interaction with N- and J-domains expressed independently, the former (residues 1-118) fused to the activin IIB receptor's membrane-spanning alpha-helix (CRF(1)-N) and the latter comprising residues 110-415 (CRF(1)-J). We also investigated the effect of nonpeptide antagonist and G-protein on ligand affinity for N- and J-domains. Peptide agonist affinity for CRF(1)-N was only 1.1-3.5-fold lower than affinity for the whole receptor (CRF(1)-R), suggesting the N-domain predominantly contributes to peptide agonist affinity. Agonist interaction with CRF(1)-J (potency for stimulating cAMP accumulation) was 12000-1500000-fold weaker than with CRF(1)-R, indicating very weak direct agonist interaction with the J-domain. Nonpeptide antagonist affinity for CRF(1)-J and CRF(1)-R was indistinguishable, indicating the compounds bind predominantly the J-domain. Agonist activation of CRF(1)-J was fully blocked by nonpeptide antagonist, suggesting antagonism results from inhibition of agonist-J-domain interaction. G-protein coupling with CRF(1)-R (forming RG) increased peptide agonist affinity 92-1300-fold, likely resulting from enhanced agonist interaction with the J-domain rather than the N-domain. Nonpeptide antagonists, which bind the J-domain, blocked peptide agonist binding to RG, and binding of peptide antagonists, predominantly to the N-domain, was unaffected by R-G coupling. These findings extend the two-domain model quantitatively and are consistent with a simple equilibrium model of the two-domain mechanism: (1) The N-domain binds peptide agonist with moderate-to-high microaffinity, substantially increasing the local concentration of agonist and so allowing weak agonist-J-domain interaction. (2) Agonist-J-domain interaction is allosterically enhanced by receptor-G-protein interaction and inhibited by nonpeptide antagonist.