Asymmetric synthesis and preliminary evaluation of (R)- and (S)-[11C]bisoprolol, a putative beta1-selective adrenoceptor radioligand

(+/-)-1-[4-(2-Isopropoxyethoxymethyl)-phenoxy]-3-isopropylamino-2-propanol (bisoprolol) is a potent, clinically used beta(1)-adrenergic agent. (R)-(+) and (S)-(-) enantiomers of bisoprolol were labelled with carbon-11 (t(1/2)=20.4 min) as putative tracers for the non-invasive assessment of the beta(1)-adrenoceptor subtype in the human heart and brain with positron emission tomography (PET). The radiosynthesis consisted of reductive alkylation of des-iso-propyl precursor with [2-11C]acetone in the presence of sodium cyanoborohydride and acetic acid. The stereo-conservative synthesis of (R)-(+) and (S)-(-)-1-[4-(2-isopropoxyethoxymethyl)-phenoxy]-3-amino-2-propanol to be used as the precursors for the radiosynthesis of [11C]bisoprolol enantiomers was readily accomplished by the use of the corresponding chiral epoxide in three steps starting from the commercially available hydroxybenzyl alcohol. The final labelled product (either (+) or (-)-1-[4-(-isopropoxyethoxymethyl)-phenoxy]-3- [11C]isopropylamino-2-propanol) was obtained in 99% radiochemical purity in 30 min with 15+/-5% (EOS, non-decay corrected) radiochemical yield and 3.5+/-1 Ci/micromol specific radioactivity. Preliminary biological evaluation of the tracer in rats showed that about 30% of heart uptake of [11C](S)-bisoprolol is due to specific binding. The high non-specific uptake in lung might mask the heart uptake, thus precluding the use of [11C](S)-bisoprolol for heart and lung studies by PET. The remarkably high uptake of the tracer in rat brain areas rich of beta-adrenergic receptors such as pituitary (1.8+/-0.3% I.D. at 30 min) was blocked by pre-treatment with the beta-adrenergic antagonists propranolol (45%) and bisoprolol (51%, p<0.05). [11C](S)-bisoprolol deserves further evaluation in other animal models as a putative beta(1) selective radioligand for in vivo investigation of central adrenoceptors.     

Small molecule inhibitors reveal an indispensable scaffolding role of RIPK2 in NOD2 signaling

RIPK2 mediates inflammatory signaling by the bacteria‐sensing receptors NOD1 and NOD2. Kinase inhibitors targeting RIPK2 are a proposed strategy to ameliorate NOD‐mediated pathologies. Here, we reveal that RIPK2 kinase activity is dispensable for NOD2 inflammatory signaling and show that RIPK2 inhibitors function instead by antagonizing XIAP‐binding and XIAP‐mediated ubiquitination of RIPK2. We map the XIAP binding site on RIPK2 to the loop between β2 and β3 of the N‐lobe of the kinase, which is in close proximity to the ATP‐binding pocket. Through characterization of a new series of ATP pocket‐binding RIPK2 inhibitors, we identify the molecular features that determine their inhibition of both the RIPK2‐XIAP interaction, and of cellular and in vivoNOD2 signaling. Our study exemplifies how targeting of the ATP‐binding pocket in RIPK2 can be exploited to interfere with the RIPK2‐XIAP interaction for modulation of NOD signaling.     

Differences in Gene Expression and Cytokine Release Profiles Highlight the Heterogeneity of Distinct Subsets of Adipose Tissue-Derived Stem Cells in the Subcutaneous and Visceral Adipose Tissue in Humans

Differences in the inherent properties of adipose tissue-derived stem cells (ASC) may contribute to the biological specificity of the subcutaneous (Sc) and visceral (V) adipose tissue depots. In this study, three distinct subpopulations of ASC, i.e. ASC_SVF, ASC_Bottom, and ASC_Ceiling, were isolated from Sc and V fat biopsies of non-obese subjects, and their gene expression and functional characteristics were investigated. Genome-wide mRNA expression profiles of ASC_SVF, ASC_Bottom and ASC_Ceiling from Sc fat were significantly different as compared to their homologous subsets of V-ASCs. Furthermore, ASC_SVF, ASC_Ceiling and ASC_Bottom from the same fat depot were also distinct from each other. In this respect, both principal component analysis and hierarchical clusters analysis showed that ASC_Ceiling and ASC_SVF shared a similar pattern of closely related genes, which was highly different when compared to that of ASC_Bottom. However, larger variations in gene expression were found in inter-depot than in intra-depot comparisons. The analysis of connectivity of genes differently expressed in each ASC subset demonstrated that, although there was some overlap, there was also a clear distinction between each Sc-ASC and their corresponding V-ASC subsets, and among ASC_SVF, ASC_Bottom, and ASC_Ceiling of Sc or V fat depots in regard to networks associated with regulation of cell cycle, cell organization and development, inflammation and metabolic responses. Finally, the release of several cytokines and growth factors in the ASC cultured medium also showed both inter- and intra-depot differences. Thus, ASC_Ceiling and ASC_Bottom can be identified as two genetically and functionally heterogeneous ASC populations in addition to the ASC_SVF, with ASC_Bottom showing the highest degree of unmatched gene expression. On the other hand, inter-depot seem to prevail over intra-depot differences in the ASC gene expression assets and network functions, contributing to the high degree of specificity of Sc and V adipose tissue in humans.     

Changes in the gene expression profiles of the brains of male European eels (Anguilla anguilla) during sexual maturation

Background

The vertebrate brain plays a critical role in the regulation of sexual maturation and reproduction by integrating environmental information with developmental and endocrine status. The European eel Anguilla anguilla is an important species in which to better understand the neuroendocrine factors that control reproduction because it is an endangered species, has a complex life cycle that includes two extreme long distance migrations with both freshwater and seawater stages and because it occupies a key position within the teleost phylogeny. At present, mature eels have never been caught in the wild and little is known about most aspects of reproduction in A. anguilla. The goal of this study was to identify genes that may be involved in sexual maturation in experimentally matured eels. For this, we used microarrays to compare the gene expression profiles of sexually mature to immature males.

Results

Using a false discovery rate of 0.05, a total of 1,497 differentially expressed genes were identified. Of this set, 991 were expressed at higher levels in brains (forebrain and midbrain) of mature males while 506 were expressed at lower levels relative to brains of immature males. The set of up-regulated genes includes genes involved in neuroendocrine processes, cell-cell signaling, neurogenesis and development. Interestingly, while genes involved in immune system function were down-regulated in the brains of mature males, changes in the expression levels of several receptors and channels were observed suggesting that some rewiring is occurring in the brain at sexual maturity.

Conclusions

This study shows that the brains of eels undergo major changes at the molecular level at sexual maturity that may include re-organization at the cellular level. Here, we have defined a set of genes that help to understand the molecular mechanisms controlling reproduction in eels. Some of these genes have previously described functions while many others have roles that have yet to be characterized in a reproductive context. Since most of the genes examined here have orthologs in other vertebrates, the results of this study will contribute to the body of knowledge concerning reproduction in vertebrates as well as to an improved understanding of eel biology.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-799) contains supplementary material, which is available to authorized users.     

Components of the Mediterranean Diet with chemopreventive activity toward colorectal cancer

Colorectal cancer is one of the leading causes of cancer incidence and death worldwide. For the past 30 years researchers have tried to find drugs suitable for the chemoprevention of the diseases. Epidemiological studies have demonstrated that adherence to the Mediterranean Diet (MD) is protective toward colon cancer development. Key components of this diet are olive oil (OO), fruits and vegetables, legumes and fish. Importantly, many bioactives present in these foods have shown anti-cancer activity in in vitro as well as in animal models of colon carcinogenesis, indicating a possible use as preventive agents. However, when translated to human trials, single bioactives have yielded conflicting results mostly due to irreproducibility of pre-clinical data. Since our preclinical models are usually designed to test single molecules at high concentrations and for very short time in order to provide significant effects, future studies should employ multiple bioactives that would resemble a more natural approach with possible significant synergisms that might be critical for cancer prevention. In this review we will discuss data obtained with components of the MD with a specific focus on OO, omega-3 polyunsaturated fatty acids and apples.     

Angiotensin-Induced Abdominal Aortic Aneurysms in Hypercholesterolemic Mice: Role of Serum Cholesterol and Temporal Effects of Exposure

Objective

Understanding variations in size and pattern of development of angiotensin II (Ang II)-induced abdominal aortic aneurysms (AAA) may inform translational research strategies. Thus, we sought insight into the temporal evolution of AAA in apolipoprotein (apo)E^−/− mice.

Approach

A cohort of mice underwent a 4-week pump-mediated infusion of saline (n = 23) or 1500 ng/kg/min of Ang II (n = 85) and AAA development was tracked via in vivo ultrasound imaging. We adjusted for hemodynamic covariates in the regression models for AAA occurrence in relation to time.

Results

The overall effect of time was statistically significant (p<0.001). Compared to day 7 of AngII infusion, there was no decrease in the log odds of AAA occurrence by day 14 (−0.234, p = 0.65), but compared to day 21 and 28, the log odds decreased by 9.07 (p<0.001) and 2.35 (p = 0.04), respectively. Hemodynamic parameters were not predictive of change in aortic diameter (Δ) (SBP, p = 0.66; DBP, p = 0.66). Mean total cholesterol (TC) was higher among mice with large versus small AAA (601 vs. 422 mg/ml, p<0.0001), and the difference was due to LDL. AngII exposure was associated with 0.43 mm (95% CI, 0.27 to 0.61, p<0.0001) increase in aortic diameter; and a 100 mg/dl increase in mean final cholesterol level was associated with a 12% (95% CI, 5.68 to 18.23, p<0.0001) increase in aortic diameter. Baseline cholesterol was not associated with change in aortic diameter (p = 0.86).

Conclusions

These are the first formal estimates of a consistent pattern of Ang II-induced AAA development. The odds of AAA occurrence diminish after the second week of Ang II infusion, and TC is independently associated with AAA size.     

A MiRNA Signature for Defining Aggressive Phenotype and Prognosis in Gliomas

Gliomas represent a disparate group of tumours for which there are to date no cure. Thus, there is a recognized need for new diagnostic and therapeutic approaches based on increased understanding of their molecular nature. We performed the comparison of the microRNA (miRNA) profile of 8 WHO grade II gliomas and 24 higher grade tumours (2 WHO grade III and 22 glioblastomas) by using the Affymetrix GeneChip miRNA Array v. 1.0. A relative quantification method (RT-qPCR) with standard curve was used to confirm the 22 miRNA signature resulted by array analysis. The prognostic performances of the confirmed miRNAs were estimated on the Tumor Cancer Genome Atlas (TCGA) datasets. We identified 22 miRNAs distinguishing grade II gliomas from higher grade tumours. RT-qPCR confirmed the differential expression in the two patients'' groups for 13 out of the 22 miRNAs. The analysis of the Glioblastoma Multiforme (GBM) and Lower Grade Glioma (LGG) datasets from TCGA demonstrated the association with prognosis for 6 of those miRNAs. Moreover, in the GBM dataset miR-21 and miR-210 were predictors of worse prognosis in both univariable and multivariable Cox regression analyses (HR 1.19, p = 0.04, and HR 1.18, p = 0.029 respectively). Our results support a direct contribution of miRNAs to glioma cancerogenesis and suggest that miR-21 and miR-210 may play a role in the aggressive clinical behaviour of glioblastomas.     

Cyclooxygenase-2 and atherosclerosis

Cyclooxygenase regulates the production of eicosanoids, which modulate physiologic processes in the vessel wall contributing to atherosclerosis and thrombosis, including platelet aggregation, control of vascular tone, and the local inflammatory response. Cyclooxygenase-1 mediates production of platelet thromboxane A(2), a potent vasoconstrictor and platelet agonist, whereas both cyclooxygenase 1 and 2 contribute to production of endothelial prostacyclin, a vasodilator that inhibits platelet activation. Concerns have been raised that cyclooxygenase-2 inhibitors may increase thrombotic cardiovascular events by disturbing the balance between platelet thromboxane A(2) and endothelial prostacyclin, but this controversial issue will only be resolved by prospective clinical trials. Because cyclooxygenase-2 is upregulated in activated monocyte/macrophages, which play a key role in the pathogenesis of atherosclerosis, we have recently tested the hypothesis that pharmacological inhibition of cyclooxygenase-2 in LDL-receptor deficient mice would reduce early atherosclerosis. After 6 weeks on a Western-type diet, male LDL-receptor deficient mice treated with either rofecoxib (a selective cyclooxygenase-2 inhibitor) or indomethacin (a non-selective cyclooxygenase inhibitor) had significant reductions in atherosclerosis when compared with control mice. Also, LDL-receptor deficient mice null for macrophage cyclooxygenase-2 were generated by fetal liver cell transplantation and developed significantly less atherosclerosis than control LDL-receptor deficient mice transplanted with fetal liver cells wildtype for cyclooxygenase-2, providing genetic evidence in support of a proatherogenic role for macrophage cyclooxygenase-2 expression. These results support the potential of antiinflammatory approaches for the prevention of atherosclerosis and identify cyclooxygenase-2 as a target for intervention.