Synthesis,high-resolution NMR spectroscopic analysis,and single-crystal X-ray diffraction of isoxazoline tetracycles

Three isoxazoline tetracycles were obtained enantiomerically pure by intramolecular 1,3-dipolar cycloaddition. The characterization of the new compounds was performed by high-resolution 1H and 13C NMR spectroscopy. The relative configuration of the new chiral centers was determined by NOESY experiments and confirmed by single-crystal X-ray structural analysis.     

ApoE genotype-specific inhibition of apoptosis

Endothelial cell apoptosis can be initiated by withdrawing growth factors or serum, and is inhibited by HDL. Our results show that the total lipoprotein population from apolipoprotein E 4/4 (APOE4/4) sera is less anti-apoptotic than total lipoproteins from other APOE genotypes, as measured by caspase 3/7 activity. Moreover, APOE4/4 VLDL antagonizes the antiapoptotic activity of HDL by a mechanism requiring binding of apoE4 on VLDL particles to an LDL family receptor. This ability of APOE4/4 VLDL to inhibit the antiapoptotic effects of HDL presents a potential mechanism by which the expression of several diseases, including atherosclerosis, is enhanced by the APOE4 genotype.     

Cardioprotection by adenosine A2A agonists in a canine model of myocardial stunning produced by multiple episodes of transient ischemia

We sought to determine whether administration of a very low, nonvasodilating dose of a highly selective adenosine A(2A) receptor agonist (ATL-193 or ATL-146e) would be cardioprotective in a canine model of myocardial stunning produced by multiple episodes of transient ischemia. Twenty-four anesthetized open-chest dogs underwent either 4 (n=12) or 10 cycles (n=12) of 5-min left anterior descending coronary artery (LAD) occlusions interspersed by 5 or 10 min of reperfusion. Left ventricular thickening was measured from baseline through 180 min after the last occlusion-reperfusion cycle. Regional flow was measured with microspheres. In 12 of 24 dogs, A(2A) receptor agonist was infused intravenously beginning 2 min prior to the first occlusion and continuing throughout reperfusion at a dose below that which produces vasodilatation (0.01 microg x kg(-1) x min(-1)). Myocardial flow was similar between control and A(2A) receptor agonist-treated animals, confirming the absence of A(2) receptor agonist-induced vasodilatation. During occlusion, there was severe dyskinesis with marked LAD zone thinning in all animals. After 180 min of reperfusion following the last cycle, significantly greater recovery of LAD zone thickening was observed in A(2A) receptor agonist-treated vs. control animals in both the 4-cycle (91 +/- 7 vs. 56 +/- 12%, respectively; P<0.05) and the 10-cycle (65 +/- 9 vs. 8 +/- 16%, respectively; P<0.05) occlusion groups. The striking amount of functional recovery observed with administration of low, nonvasodilating doses of adenosine A(2A) agonist ATL-193 or ATL-146e supports their further evaluation for the attenuation of postischemic stunning in the clinical setting.     

Leptospira species promote a pro‐inflammatory phenotype in human neutrophils

Leptospirosis is a global zoonosis caused by pathogenic Leptospira. Neutrophils are key cells against bacterial pathogens but can also contribute to tissue damage. Because the information regarding the role of human neutrophils in leptospirosis is scant, we comparatively analysed the human neutrophil's response to saprophytic Leptospira biflexa serovar Patoc (Patoc) and the pathogenic Leptospira interrogans serovar Copenhageni (LIC). Both species triggered neutrophil responses involved in migration, including the upregulation of CD11b expression, adhesion to collagen, and the release of IL‐8. In addition, both species increased levels of pro‐inflammatory IL‐1β and IL‐6 associated with the inflammasome and NFκB pathway activation and delayed neutrophil apoptosis. LIC was observed on the neutrophil surface and not phagocytized. In contrast, Patoc generated intracellular ROS associated with its uptake. Neutrophils express the TYRO3, AXL, and MER receptor protein tyrosine kinases (TAM), but only LIC selectively increased the level of AXL. TLR2 but not TLR4‐blocking antibodies abrogated the IL‐8 secretion triggered by both Leptospira species. In summary, we demonstrate that Leptospira species trigger a robust neutrophil activation and pro‐inflammatory response. These findings may be useful to find new diagnostic markers and therapeutic strategies against leptospirosis.     

The Physiological Response of Two Green Calcifying Algae from the Great Barrier Reef towards High Dissolved Inorganic and Organic Carbon (DIC and DOC) Availability

Increasing dissolved inorganic carbon (DIC) concentrations associated with ocean acidification can affect marine calcifiers, but local factors, such as high dissolved organic carbon (DOC) concentrations through sewage and algal blooms, may interact with this global factor. For calcifying green algae of the genus Halimeda, a key tropical carbonate producer that often occurs in coral reefs, no studies on these interactions have been reported. These data are however urgently needed to understand future carbonate production. Thus, we investigated the independent and combined effects of DIC (pCO₂ 402 μatm/ pH_tot 8.0 and 996 μatm/ pH_tot 7.7) and DOC (added as glucose in 0 and 294 μmol L^-1) on growth, calcification and photosynthesis of H. macroloba and H. opuntia from the Great Barrier Reef in an incubation experiment over 16 days. High DIC concentrations significantly reduced dark calcification of H. opuntia by 130 % and led to net dissolution, but did not affect H. macroloba. High DOC concentrations significantly reduced daily oxygen production of H. opuntia and H. macroloba by 78 % and 43 %, respectively, and significantly reduced dark calcification of H. opuntia by 70%. Combined high DIC and DOC did not show any interactive effects for both algae, but revealed additive effects for H. opuntia where the combination of both factors reduced dark calcification by 162 % compared to controls. Such species-specific differences in treatment responses indicate H. opuntia is more susceptible to a combination of high DIC and DOC than H. macroloba. From an ecological perspective, results further suggest a reduction of primary production for Halimeda-dominated benthic reef communities under high DOC concentrations and additional decreases of carbonate accretion under elevated DIC concentrations, where H. opuntia dominates the benthic community. This may reduce biogenic carbonate sedimentation rates and hence the buffering capacity against further ocean acidification.