Synthesis and biological activity of 4-methyl-3,5-dioxane derivatives as thromboxane A2 receptor antagonists

The synthesis and biological activity of novel 4-methyl-3,5-dioxane analogues are described. All compounds were produced through modification of the substituent formally corresponding to the omega-octenol side chain of thromboxane A2 (TXA2), in reference to the structure of SQ29548. Several compounds were found to be potent TXA2 receptor antagonists. Compound 8b was the most effective inhibitor of 9,11-epoxymethano PGH2 (U-46619)-induced human platelet aggregation (IC50 = 7.4 nM).     

Generation of constitutively active calcineurin by calpain contributes to delayed neuronal death following mouse brain ischemia

Calpain, a Ca(2+)-dependent cysteine protease, in vitro converts calcineurin (CaN) to constitutively active forms of 45 kDa and 48 kDa by cleaving the autoinhibitory domain of the 60 kDa subunit. In a mouse middle cerebral artery occlusion (MCAO) model, calpain converted the CaN A subunit to the constitutively active form with 48 kDa in vivo. We also confirmed increased Ca(2+)/CaM-independent CaN activity in brain extracts. The generation of constitutively active and Ca(2+)/CaM-independent activity of CaN peaked 2 h after reperfusion in brain extracts. Increased constitutively active CaN activity was associated with dephosphorylation of dopamine-regulated phosphoprotein-32 in the brain. Generation of constitutively active CaN was accompanied by translocation of nuclear factor of activated T-cells (NFAT) into nuclei of hippocampal CA1 pyramidal neurons. In addition, a novel calmodulin antagonist, DY-9760e, blocked the generation of constitutively active CaN by calpain, thereby inhibiting NFAT nuclear translocation. Together with previous studies indicating that NFAT plays a critical role in apoptosis, we propose that calpain-induced CaN activation in part mediates delayed neuronal death in brain ischemia.     

Pleuromutilin derivatives having a purine ring. Part 1: new compounds with promising antibacterial activity against resistant Gram-positive pathogens

In the course of our research aimed at the discovery of metabolic stable pleuromutilin derivatives with more potent antibacterial activity against Gram-positive pathogens than previous analogues, a series of compounds bearing a purine ring were prepared and evaluated. From SAR studies, we identified two promising compounds 85 and 87, which have excellent in vitro activity against a number of Gram-positive pathogens, including existing drug-resistant strains, and potent in vivo efficacy.     

Perylene-conjugated pyrrole polyamide as a sequence-specific fluorescent probe

Perylene-conjugated pyrrole (Py)-polyamide 2 was designed and synthesized using the Fmoc solid-phase synthesis and a subsequent Sonogashira coupling reaction with 3-bromoperylene. Interestingly, conjugate 2 did not luminesce in water at 313 nm irradiation but was turned on in the presence of target double-stranded (ds) DNA, and showed strong emission with increasing DNA concentration, in particularly, by the binding to the target telomere sequences through heterodimer formation with partner 3. Importantly, the excitation spectrum of 2 clearly indicates that the Py and Imidazole (Im) moieties in the polyamide effectively sensitize the perylene moiety to give rise to fluorescence emission. Energy transfer would occur from the Py moiety to the perylene. Thus, screening of perylene-conjugates will allow us to develop a novel "molecular light switch" with sequence-specificity.     

Fatty acid-binding protein regulates LPS-induced TNF-alpha production in mast cells

There has been increasing evidence for the involvement of fatty acid-binding proteins (FABPs) in the cytokine production of macrophages and dendritic cells probably through the control of cellular lipid metabolism and signal transduction. Since mast cells (MCs) are recently shown to be involved in immune response through modification of cytokine production, it is possible that some FABPs could also be involved in the immune response of MCs. In this study, we found that epidermal-type FABP (E-FABP) was expressed in murine bone marrow-derived MCs (BMMCs). Using BMMCs from genetically E-FABP-null mutated mice, we demonstrated that E-FABP in BMMCs plays a key role in the production of TNF-alpha following lipopolysaccharide (LPS) stimulation. In the in vivo septic peritonitis model (cecal ligation and puncture model), E-FABP-null mice showed a significantly increased mortality compared to wild-type mice. However, no significant difference in antigen-induced cytokine production was observed between wild-type and E-FABP-null BMMCs, and systemic anaphylaxis was equally induced in vivo in both wild-type and E-FABP-null mice. These results suggest that E-FABP is specifically involved in the LPS-induced cytokine production of MCs, and could play a role in the host-defense against bacterial infection, possibly through regulation of TNF-alpha production.     

An enhanced glucose biosensor using charge transfer techniques

An enhanced glucose biosensor based on a charge transfer technique glucose sensor (CTTGS) is described and demonstrated experimentally. In the proposed CTTGS, which is accumulation method (d-gluconate+H(+)) ion perception system, the quality of output signal with "signal integration cycles" is high. With the proposed CTTGS it is possible to amplify the sensing signals without an external amplifier by using an accumulation cycle. It can be supposed that measurements of small (d-gluconate+H(+)) ion fluctuation are difficult by ion-sensitive field effect transistor (ISFET) because the theoretical maximum sensitivity is only 59 mV/pH and the small output signals are buried in the 1/f noise component of the metal-insulator-semi-conductor field-effect transistor (MISFET). Therefore, the CTTGS has many advantages, such as high sensitivity, high accuracy, high signal-to-noise ratio (SNR), and has been successfully demonstrated using a charge transfer technique. The CTTGS exhibited excellent performance for glucose with a large span (1445 mV) and good reproducibility. Moreover, the CTTGS has good sensitivity in this range of 7.22mV/mM, a lower detection limit of about 0.01 mM/L and an upper detection limit of about 200 mM/L compared with amperometric glucose analysis which has been studied recently. Under optimum conditions, the proposed CTTGS exceeds the performance of the widely used ISFET glucose sensor. The sensitivity of the CTTGS (7.22 mV/mM) was seven times higher than that of the ISFET (1 mV/mM). Furthermore, the sensitivity obtained for human glucose levels was 29.06 mV/mM with a non-linear error of +/-0.27%; the linearity is y=0.0294x+1.8612 and R(2)=0.9999, which is acceptable for clinical application. Real sample analysis is investigated in blood glucose level by our developed CTTGS ISFET system.     

Novel oxime and oxime ether derivatives of 12,14-dichlorodehydroabietic acid: design, synthesis, and BK channel-opening activity

Oxime ether derivatives of the benzylic ketone of 12,14-dichlorodehydroabietic acid (diCl-DHAA, 4b) were synthesised, and their BK channel-opening activity was evaluated in an assay system of CHO-K1 cells expressing hBKalpha channels. Oxime ether structure on the B ring of diCl-DHAA significantly increased the BK channel-opening activity.