The mechanism of thrombocytopenia caused by cholesterol-conjugated antisense oligonucleotides.

In this study, we investigated thrombocytopenia caused by cholesterol-conjugated antisense oligonucleotides (Chol-ASO). First, we evaluated platelet activation induced by Chol-ASO in mice by flow cytometry after administration of platelet-rich plasma (PRP). An increase in the number of large particle-size events with platelet activation was detected in the Chol-ASO-treated group. In a smear study, numerous platelets were observed to attach to nucleic acid-containing aggregates. A competition binding assay showed that the conjugation of cholesterol to ASOs increased their affinity for glycoprotein VI. Platelet-free plasma was then mixed with Chol-ASO to form aggregates. The assembly of Chol-ASO was confirmed by dynamic light scattering measurements in the concentration range in which the formation of aggregates with plasma components was observed. In conclusion, the mechanism by which Chol-ASOs causes thrombocytopenia is proposed to be as follows: (1) Chol-ASOs form polymers, (2) the nucleic acid portion of the polymers interacts with plasma proteins and platelets, which cross-links them to form aggregates, and (3) platelets bound to aggregates become activated, resulting in platelet aggregation, leading to a decrease in platelet count in vivo. The details of the mechanism revealed in this study could contribute to creating safer oligonucleotide therapies without the risk of thrombocytopenia.

Design and Identification of a GPR40 Full Agonist (SCO-267) Possessing a 2-Carbamoylphenyl Piperidine Moiety.

GPR40/FFAR1 is a G-protein-coupled receptor expressed in pancreatic ß-cells and enteroendocrine cells. GPR40 activation stimulates secretions of insulin and incretin, both of which are the pivotal regulators of glycemic control. Therefore, a GPR40 agonist is an attractive target for the treatment of type 2 diabetes mellitus. Using the reported biaryl derivative 1, we shifted the hydrophobic moiety to the terminal aryl ring and replaced the central aryl ring with piperidine, generating 2-(4,4-dimethylpentyl)phenyl piperidine 4a, which had improved potency for GPR40 and high lipophilicity. We replaced the hydrophobic moiety with N-alkyl-N-aryl benzamides to lower the lipophilicity and restrict the N-alkyl moieties to the presumed lipophilic pocket using the intramolecular π-π stacking of cis-preferential N-alkyl-N-aryl benzamide. Among these, orally available (3S)-3-cyclopropyl-3-(2-((1-(2-((2,2-dimethylpropyl)(6-methylpyridin-2-yl)carbamoyl)-5-methoxyphenyl)piperidin-4-yl)methoxy)pyridin-4-yl)propanoic acid (SCO-267) effectively stimulated insulin secretion and GLP-1 release and ameliorated glucose tolerance in diabetic rats via GPR40 full agonism.

Radiographic Measurements as a Predictor of Correction Loss in Conservative Treatment of Colles' Fracture.

Dorsal displaced distal radius fracture (Colles' fracture) is very common and could occur from fragility in middle-aged and elderly people. Many Colles' fractures are still treated conservatively in clinics without hospitalization. Internal fixation using a palmar locking plate has been the standard treatment, but some complications have been reported. The aim of this study was to analyze changes in radiographic parameters over time in patients with conservatively treated Colles' fractures, and to establish whether the type of fracture influenced these changes. Prospective data collected included patient characteristics and radiological findings. The study was conducted at two private clinics and included 60 patients (13 men and 47 women; mean age, 72.5 years old; range, 55 to 96 years old) with a Colles' fracture (types of injury: intramedullary [n = 15], anatomical [n = 39], extramedullary [n = 2], and unknown [n = 4]) who were treated conservatively with manipulation and cast immobilization. Conservative, non-surgical treatment with manipulation was performed first, then, cast immobilization continued for 4 weeks. Loss of correction between the time of reduction and the final observation was defined by the following radiographic measurements: palmar tilt, radial inclination, and ulnar variance. The average final follow up period was 4.6 months (1.5-12 months). Immediately after reduction, 11 intramedullary fractures, 42 anatomical fractures and 7 extramedullary fractures were confirmed. Correction loss according to ulnar variance was significantly greater (P = 0.012) during the final observation for patients with an intramedullary injury at reduction than that for patients with extramedullary and anatomical injuries at reduction. We found that the correction loss for ulnar variance from immediately after reduction until the final observation was significantly greater in the intramedullary group, suggesting that an alternative to conservative treatment may be beneficial for patients with intramedullary fractures.

Identification of 3,4-dihydro-2H-thiochromene 1,1-dioxide derivatives with a phenoxyethylamine group as highly potent and selective α1D adrenoceptor antagonists.

A series of phenoxyethylamine derivatives was designed and synthesized to discover potent and selective human α1D adrenoceptor (α1D adrenergic receptor; α1D-AR) antagonists. Compound 7 was taken from our internal compound collection as an attractive starting point and exhibited moderate binding affinity for α1D-AR and high selectivity against α1A- and α1B-ARs. We focused on modifying the 2-methylsulfonylbenzyl group of 7 to discover novel compounds structurally distinct from other reported α1-AR antagonists containing the phenoxyethylamine motif. Study of structure activity relationship guided by a targeted ligand-lipophilicity efficiency score led to the discovery of a novel scaffold of 3,4-dihydro-2H-thiochromene 1,1-dioxide for selective α1D-AR antagonists. Further optimization studies resulted in the identification of (4S)-N4-[2-(2,5-difluorophenoxy)ethyl]-N6-methyl-3,4-dihydro-2H-thiochromene-4,6-diamine 1,1-dioxide, (S)-41, as a novel, highly potent and selective α1D-AR antagonist. Herein, we provide details of the structure activity relationship of the phenoxyethylamine analog for the potency and selectivity.

Chemical structure-guided design of dynapyrazoles, cell-permeable dynein inhibitors with a unique mode of action.

Cytoplasmic dyneins are motor proteins in the AAA+ superfamily that transport cellular cargos toward microtubule minus-ends. Recently, ciliobrevins were reported as selective cell-permeable inhibitors of cytoplasmic dyneins. As is often true for first-in-class inhibitors, the use of ciliobrevins has in part been limited by low potency. Moreover, suboptimal chemical properties, such as the potential to isomerize, have hindered efforts to improve ciliobrevins. Here, we characterized the structure of ciliobrevins and designed conformationally constrained isosteres. These studies identified dynapyrazoles, inhibitors more potent than ciliobrevins. At single-digit micromolar concentrations dynapyrazoles block intraflagellar transport in the cilium and lysosome motility in the cytoplasm, processes that depend on cytoplasmic dyneins. Further, we find that while ciliobrevins inhibit both dynein's microtubule-stimulated and basal ATPase activity, dynapyrazoles strongly block only microtubule-stimulated activity. Together, our studies suggest that chemical-structure-based analyses can lead to inhibitors with improved properties and distinct modes of inhibition.

Stereoselective synthesis of cis-beta-methyl- and phenyl-substituted alkenylboronates by platinum-catalyzed dehydrogenative borylation.

Changing places: Intramolecular B(pin)/H exchange took place in the presence of a platinum-phosphane catalyst, giving synthetically useful cis-beta-methyl-substituted alkenylboronates stereoselectively (see scheme; B(pin) = 4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl).

Ligand-controlled, complementary stereoselectivity in the platinum-catalyzed intramolecular silaboration of alkenes.

An intramolecular silaboration of borylsilanyl homoallyl ethers was achieved using a platinum catalyst, giving 1-oxa-2-silacyclopentanes in high yields. The stereoselectivity of the reactions of sec-homoallyl ethers strongly depended on the phosphorus ligand of the platinum catalysts used. The platinum complex bearing the PCyPh2 ligand was found to be the most trans-selective catalyst (trans/cis = 81:19-92:8), whereas a highly cis-selective cyclization was achieved using a platinum catalyst having tris(2,4-di-tert-butylphenyl)phosphite ligand (trans/cis = 8:92-6:94). The synthetic utility of the intramolecular silaboration was demonstrated by the complementary synthesis of a pair of diastereomers of 6-methylheptane-1,3,5-triol.