This paper describes an extended structure-activity relationships study of aminotetralin-piperazine-based hybrid molecules developed earlier for dopamine D2/D3 receptors. Various analogues as positional isomers have been developed where location of the phenolic hydroxyl group has been varied on the aromatic ring. Between two catechol derivatives, compound 6e with a two methylene linker length exhibited higher affinity and selectivity for D3 over D2 receptors over compound 6f with four methylene linkers (D2/D3 = 50.6 vs 7.51 for 6e and 6f, respectively). In general, the (-)-isomer was more potent than the (+)-isomeric counterpart. Binding results indicated highest selectivity for D3 receptors in compound (-)- 10 ( K i = 0.35 nM; D2/D3 = 71). In the 5-hydroxy series, highest selectivity for D3 receptors was exhibited by compound (-)- 25 ( K i = 0.82 nM; D2/D3 = 31.5). Most potent compounds exhibited binding and functional affinities at the sub-nanomolar level for the D3 receptor. Binding assays were carried out with HEK-293 cells expressing either D2 or D3 receptors by using tritiated spiperone as radioligand for competition studies to evaluate inhibition constants ( K i). A functional assay of selected compounds for stimulating GTPgammaS binding was carried out with CHO cells expressing human D2 receptors and AtT-20 cells expressing human D3 receptors. The functional assay results indicated partial to full agonist characteristics of test compounds. Compound (-)- 25 was selected further for in vivo study to evaluate its potency in producing contralateral rotations in rats with unilateral lesion in the nigrostriatal region induced by neurotoxin 6-OHDA, a Parkinsonian animal model. Compound (-)- 25 at 5 micromol/kg exhibited rotational activity that lasted beyond 12 h, whereas at a 1 micromol/kg dose the rotations lasted beyond 8 h.

PIKfyve is a lipid kinase that is essential for the synthesis of phosphatidylinositol-3,5-bisphosphate [PtdIns(3,5)P2], and for the regulation of membrane dynamics within the endolysosomal system in mammals. Depletion of intracellular pools of PtdIns(3,5)P2 in humans and in mice is associated with neurodegeneration and early lethality. However, the biological role of PtdIns(3,5)P2 in non-neural tissues is not well understood. Platelets are hematopoietic cells that function in a variety of physiological responses. Essential to many of these functions is the activation-dependent release of effectors from distinct storage granules - alpha granules, dense granules, and lysosomes - that derive from the endolysosomal system. Here we show that platelet-specific ablation of the PIKfyve gene in mice results in accelerated arterial thrombosis, but also unexpectedly to multiorgan defects that impair development, body mass, fertility, and survival by inducing inappropriate inflammatory responses characterized by macrophage accumulation in multiple tissues. Platelet depletion in vivo significantly impairs the progression of multiorgan defects in these mice, confirming that these defects reflect a platelet-specific process. Although PIKfyve-null platelets generate and release normal amounts of alpha granule and dense granule contents, they develop defective maturation and excessive storage of lysosomal enzymes, which are released upon platelet activation. Remarkably, impairing the secretion of lysosomes from PIKfyve-deficient platelets in vivo significantly attenuates the multiorgan defects in mice, suggesting that platelet lysosome secretion contributes to pathogenesis. Together, these results demonstrate that PIKfyve is an essential regulator for the biogenesis of platelet lysosomes, and highlight the previously unrecognized and important pathological contributions of platelet lysosomes in inflammation, arterial thrombosis, and macrophage biology.

Vapor−liquid equilibrium (VLE) data are reported for binary and mixed electrolyte solutions containing CaCl 2 , MgCl 2 , K 2 SO 4 , MgSO 4 , and KCl at total molality of salt between (0.0 and 12.0) mol•kg −1 . The measurements were carried out with a pressure between (6.3 and 101.3) kPa in a computer-controlled glass apparatus. An activity coefficient model based on the hypothesis of hydration was deduced in this paper. Experimental data and literature data for 20 salts, with temperature spanning from (273.15 to 415.85) K, were successfully correlated using the developed model. Meanwhile, the model was also successfully applied to predict the VLE data in mixed electrolyte solution systems with the binary parameters.