Search

Cyclic guanosine 3',5'-monophosphate (cGMP) is the key second messenger molecule in nitric oxide signaling. Its rapid generation and fate, but also its role in mediating acute cellular functions has been extensively studied. In the past years, genetic studies suggested an important role for cGMP in affecting the risk of chronic cardiovascular diseases, for example, coronary artery disease and myocardial infarction. Here, we review the role of cGMP in atherosclerosis and other cardiovascular diseases and discuss recent genetic findings and identified mechanisms. Finally, we highlight open questions and promising research topics.

AimThe role of platelets in atherosclerosis remains incompletely understood. Variants in genes encoding the soluble guanylyl cyclase (sGC) in platelets are associated with coronary artery disease (CAD) risk. Here we sought to investigate the contribution of platelet sGC to atherosclerosis and the therapeutic potential of targeting sGC in atherosclerosis.Methods and ResultsWe genetically deleted sGC in platelets of atherosclerosis-prone Ldlr-/- mice. By intravital fluorescence microscopy such Pf4-Cre+Gucy1b1flox/floxLdlr-/- mice displayed enhanced leukocyte adhesion to atherosclerotic plaques in comparison with their litter mates. Moreover, histological and flow cytometry analyses revealed more numerous inflammatory leukocytes and larger plaque sizes in aortic tissue of Ldlr-/- mice lacking sGC in platelets. In vitro, supernatant from activated platelets lacking sGC promoted leukocyte adhesion to endothelial cells (EC) via enhanced EC activation. Using cytokine profiling, we identified reduced angiopoietin-1 release by Pf4-Cre+Gucy1b1flox/flox and human GUCY1A1 risk allele carrier platelets to be responsible for enhanced activation of EC and subsequent leukocyte adhesion. Pharmacological sGC stimulation increased platelet angiopoietin-1 release in vitro and reduced recruitment of adoptively transferred leukocytes in Ldlr-/- mice fed a Western diet. Pharmacological sGC stimulation further reduced atherosclerotic plaque formation and vascular inflammation.ConclusionLoss of sGC in platelets contributes to atherosclerotic plaque formation via reduced release of the soluble factor angiopoietin-1 and, subsequently, enhanced leukocyte recruitment. Pharmacological sGC stimulation might represent a novel therapeutic strategy to prevent and treat CAD.Translational perspectiveReduced platelet soluble guanylyl cyclase activity contributes to atherosclerotic plaque formation and vascular inflammation. Stimulators of the soluble guanylyl cyclase, an emerging class of drugs already used in pulmonary hypertension and heart failure, are able to reduce atherosclerosis and inflammation in this preclinical model. Together with evidence from human genetics, our findings suggest a promising role of soluble guanylyl cyclase stimulation to prevent coronary artery disease.

International audience; Cultured marble is a blend of unsaturated polyester and calcium carbonate that is combined with pigments and additives to produce a wide range of colours and realistic, natural-looking patterns. This study aims to investigate process conditions (catalyst, temperature, cured time, etc …) of cultured marble at high temperatures. The optimized process conditions are obtained by thermal analysis from DSC with a temperature of 110°C and curing time of 20 min, respectively. The optimum catalyst for process conditions in a bulk moulding compound (BMC) machine is 2 phr of benzoyl peroxide (BPO). The styrene amount in UP resin is determined at 37.40% by the Gas chromatography-mass spectroscopy – headspace (GCMS-HS) technique. Anhydride maleic (MA) is found to improve outstanding mechanical properties in terms of flexural properties, the strength of impact, and the resistance of volume shrinkage of UP resin in cultured marble material.

A comparison was made to investigate the structures and bonding of nickel complex that carry tetrylone and tetrylene ligands [(CO)2Ni-{E(PH3)2}] (Ni1E) and [(CO)2Ni-{NHEMe}] (Ni2E) (E = C to Pb) using quantum chemical calculations at the BP86 level with various basis sets (SVP, TZVPP, TZ2P+). The nature of the Ni–E bonds was analyzed with charge- and energy decomposition methods. The structures of tetrylone complexes Ni1E exhibit an interesting trend with the ligands E(PH3)2 are bonded in a tilted orientation relative to the fragment Ni(CO)2. In contrast, the calculated equilibrium structures of complexes Ni2E exhibit the NHEMe ligands (E = C to Sn) bonded in a head-on way to the Ni(CO)2 fragment, while the bending angle gives the strongest side-on bonded ligand NHPbMe when E = Pb. The interesting trend of the bond dissociation energy (BDE) is observed for the tetrylone, which has the same trend BDEs compared with tetrylene complexes. The EDA-NOCV results indicate that the tetrylone ligands {E(PH3)2} in complexes are similar to the tetrylene ligands NHEMe as strong σ-donors and weak π-acceptors. The BDEs calculated for the Ni–E bonds in Ni1E and Ni2E show that the effect of bulky ligands may obscure the intrinsic Ni–E bond strength. The bonding analysis shows that the tetrylone ligands in Ni1E may act in a similar fashion to the tetrylene ligands in Ni2E. All complexes Ni1E and Ni2E are suitable targets for synthesis.

We computationally investigated the structure and bonding situation of bis-gold chloride complexes, (AuCl)2, containing N-heterocyclic carbenes and analogues, called tetrylenes [(AuCl)2-NHEMe] (Au2-NHE) with E=C to Pb, using density functional theory (DFT) at the BP86 level with the basis sets def2-SVP, def2-TZVPP, and TZ2P+. The nature of the (AuCl)2-NHEMe bond in the Au2-NHE complexes was analyzed using charge and energy decomposition methods. The calculated equilibrium structures of the Au2-NHE complexes showed that the tetrylene ligands, NHEMe (E=C to Ge), are bonded in a head-on fashion to the bis-gold chloride fragment, (AuCl)2, and that the structure of Au2-NHSn contains a distorted head-on NHSn ligand, and the NHPb ligand is bonded in a side-on mode to the bis-gold chloride fragment, (AuCl)2. The theoretical calculation of bond dissociation energy (BDE) suggests that the bis-gold chloride-NHEMe bond strength increases from Au2-NHC to Au2-NHSi and then significantly decreases from Au2-NHSi to Au2-NHSn, and the strongest bond is exhibited for Au2-NHPb. The EDA-NOCV results and NOCV pairs indicate that the NHEMe ligand in the Au2-NHE complexes is a strong σ-donor and a weak π-acceptor, as well as a very weak π-donor (AuCl)2←{NHEMe}. The trend in the Au-E bond strength resulted from the increase in (AuCl)2←NHEMe donation. The results of this study may establish an interesting class of compounds worthy of further study.

Quantum chemical calculations at the BP86 level with various basis sets (SVP, TZVPP, and TZ2P+) were carried out for the Fe(CO)4 of group-13 half-sandwich ECp* [Fe(CO)4-ECp*] (Fe4-E) (E = B to Tl). The chemical bonding of the Fe(CO)4-ECp* bond was analyzed with charge- and energy decomposition methods. The calculated equilibrium structures of complexes Fe4-E show that the ligands ECp* are bonded in an end-on way to the fragment Fe(CO)4 in Fe4-E with E = B to Ga. The compound Fe4-In has a distorted end-on ligand InCp*. In contrast, Fe4-Tl has a side-on bonded ligand TlCp*. The calculated bond dissociation energies (BDEs) suggest that the bond in the iron group-13 half-sandwich complexes Fe4-E decreases from Fe4-B to Fe4-Tl. Natural bond orbital (NBO) analysis of the bonding situation reveals that the Fe(CO)4ECp* donation in Fe4-E comes from the σ lone-pair orbital of ECp*. Bonding analysis indicates that the ligand ECp* in complexes are strong σ donors and the NOCV pairs of the bonding show small π-back donation from the Fe(CO)4 to the ECp* ligands.

A scheme for chemical bond analysis by combining the energy decomposition analysis (EDA) method with natural orbitals for chemical valence (NOCV) theory has been investigated. Quantum chemical calculations at the BP86/TZ2P+ level of theory are performed for a comparison of chemical bond analysis between tetrylones [BH3-{E(PH3)2}] (B3-EP2) and tetrylenes [(BH3-{NHEMe}] (B3-NHE) (E = C to Pb). The EDA-NOCV results suggest that the B–E bond dissociation energies (BDEs) in tetrylones and tetrylenes decrease from the slighter to the heavier homologs. The decrease in the bond strengths from the lighter to the heavier homologs of B3-EP2 comes mainly from the decrease in the electrostatic attractions ΔEelstat and the orbital interactions ΔEorb, while the decrease in the bond strength from carbene B3-NHC to plumbylene B3-NHPb strongly correlates with the decrease in electrostatic term ΔEelstat.

Soluble guanylyl cyclase (sGC) is the physiological receptor for nitric oxide (NO) and NO-releasing drugs, and is a key enzyme in several cardiovascular signaling pathways. Its activation induces the synthesis of the second messenger cGMP. cGMP regulates the activity of various downstream proteins, including cGMP-dependent protein kinase G, cGMP-dependent phosphodiesterases and cyclic nucleotide gated ion channels leading to vascular relaxation, inhibition of platelet aggregation, and modified neurotransmission. Diminished sGC function contributes to a number of disorders, including cardiovascular diseases. Knowledge of its regulation is a prerequisite for understanding the pathophysiology of deficient sGC signaling. In this review we consolidate the available information on sGC signaling, including the molecular biology and genetics of sGC transcription, translation and function, including the effect of rare variants, and present possible new targets for the development of personalized medicine in vascular diseases.

Background: A chromosomal locus at 4q32.1 has been genome-wide significantly associated with coronary artery disease risk. The locus encompasses GUCY1A3 , which encodes the α 1 subunit of the soluble guanylyl cyclase (sGC), a key enzyme in the nitric oxide/cGMP signaling pathway. The mechanism linking common variants in this region with coronary risk is not known. Methods: Gene expression and protein expression were analyzed with quantitative polymerase chain reaction and immunoblotting, respectively. Putative allele-specific transcription factors were identified with in silico analyses and validated via allele-specific quantification of antibody-precipitated chromatin fractions. Regulatory properties of the lead risk variant region were analyzed with reporter gene assays. To assess the effect of zinc finger E box-binding homeobox 1 transcription factor (ZEB1), siRNA-mediated knockdown and overexpression experiments were performed. Association of GUCY1A3 genotype and cellular phenotypes was analyzed with vascular smooth muscle cell migration assays and platelet aggregation analyses. Results: Whole-blood GUCY1A3 mRNA levels were significantly lower in individuals homozygous for the lead (rs7692387) risk variant. Likewise, reporter gene assays demonstrated significantly lower GUCY1A3 promoter activity for constructs carrying this allele. In silico analyses located a DNase I hypersensitivity site to rs7692387 and predicted binding of the transcription factor ZEB1 rather to the nonrisk allele, which was confirmed experimentally. Knockdown of ZEB1 resulted in more profound reduction of nonrisk allele promoter activity and a significant reduction of endogenous GUCY1A3 expression. Ex vivo–studied platelets from homozygous nonrisk allele carriers displayed enhanced inhibition of ADP-induced platelet aggregation by the nitric oxide donor sodium nitroprusside and the phosphodiesterase 5 inhibitor sildenafil compared with homozygous risk allele carriers. Moreover, pharmacological stimulation of sGC led to reduced migration only in vascular smooth muscle cells homozygous for the nonrisk allele. In the Hybrid Mouse Diversity Panel, higher levels of GUCY1A3 expression correlated with less atherosclerosis in the aorta. Conclusions: Rs7692387 is located in an intronic site that modulates GUCY1A3 promoter activity. The transcription factor ZEB1 binds preferentially to the nonrisk allele, leading to an increase in GUCY1A3 expression, higher sGC levels, and higher sGC activity after stimulation. Finally, human and mouse data link augmented sGC expression to lower risk of atherosclerosis.

In this study, pH indicative films were successfully synthesized from hydrogels made by blending 1% poly(vinyl alcohol) (PVA) and 1% chitosan (CS) with anthocyanin (ATH) and sodium tripolyphosphate (STPP). Particularly, ATH extracted from red cabbage was used as the pH indicator, while STPP was utilized as the cross-linking agent to provide better mechanical properties of the cast films. FT-IR spectra confirmed the existence of the ATH in the cast films. Moreover, the tensile strength, the elongation-at-break, and the swelling indices of the cast films were measured. In general, these properties of pH indicative films were profoundly influenced by the compositions of PVA/CS and the STPP dosage applied in the hydrogels. For example, the tensile strength could change from 43.27 MPa on a film cast from pure PVA hydrogel to 29.89 MPa, if 35% of the PVA hydrogel was substituted with CS. The cast films were applied as a food wrap that could be used to monitor visually the quality of the enwrapped food via the color change of the film upon the variation in pH values of the enwrapped food. In practice, a sequential change in color was successfully observed on the pH indicative films partially enwrapping the pork belly, indicating the spoilage of the meat.

Biodiesel production from transesterification of vegetable oils in excess methanol was performed by using as -prepared catalyst from low-cost kaolin clay. This effective heterogeneous catalyst was successfully prepared from natural kaolin firstly by dehydroxylation at 800 °C for 10 h and, subsequently, by NaOH-activation hydrothermally at 90 °C for 24 h and calcined again at 500 °C for 6 h. The as -obtained catalytic material was characterized with instruments, including FT-IR, XRD, SEM, and porosimeter (BET/BJH analysis). The as -prepared catalyst was advantageous not only for its easy preparation, but also for its cost-efficiency and superior catalysis in transesterification of vegetable oils in excess methanol to produce fatty acid methyl esters (FAMEs). Conversion efficiencies of soybean and palm oils to biodiesel over the as -prepared catalysts reached 97.0 ± 3.0% and 95.4 ± 3.7%, respectively, under optimal conditions. Activation energies of transesterification reactions of soybean and palm oils in excess methanol using these catalysts are 14.09 kJ/mol and 48.87 kJ/mol, respectively.

Stimulators of the soluble guanylyl cyclase (sGC) are emerging therapeutic agents in cardiovascular diseases. Genetic alterations of the GUCY1A3 gene, which encodes the alpha(1) subunit of the sGC, are associated with coronary artery disease. Studies investigating sGC stimulators in subjects with CAD and carrying risk-related variants in sGC are, however, lacking. Here, we functionally investigate the impact of coding GUCY1A3 variants on sGC activity and the therapeutic potential of sGC stimulators in vitro. In addition to a known loss-of-function variant, eight coding variants in GUCY1A3 were cloned and expressed in HEK 293 cells. Protein levels and dimerization capability with the beta(1) subunit were analysed by immunoblotting and co-immunoprecipitation, respectively. All alpha(1) variants found in MI patients dimerized with the beta(1) subunit. Protein levels were reduced by 72 % in one variant (p < 0.01). Enzymatic activity was analysed using cGMP radioimmunoassay after stimulation with a nitric oxide (NO) donor. Five variants displayed decreased cGMP production upon NO stimulation (p < 0.001). The addition of the sGC stimulator BAY 41-2272 increased cGMP formation in all of these variants (p < 0.01). Except for the variant leading to decreased protein level, cGMP amounts reached the wildtype NO-induced level after addition of BAY 41-2272. In conclusion, rare coding variants in GUCY1A3 lead to reduced cGMP formation which can be rescued by a sGC stimulator in vitro. These results might therefore represent the starting point for discovery of novel treatment strategies for patients at risk with coding GUCY1A3 variants.

Myocardial infarction (MI) is the main complication of coronary artery disease (CAD). Recently, a locus tagging the GUCY1A3 gene has been shown to be genome-wide significantly associated with CAD [1]. GUCY1A3 encodes for the α1-subunit of the soluble guanylyl cyclase (sGC) which consists of α1- and β1-subunits and catalyzes the production of cGMP upon stimulation with nitric oxide (NO). cGMP acts a second messenger that mediates diverse cellular functions, e.g. smooth muscle relaxation and inhibition of platelet aggregation. Using whole-exome sequencing, our group also identified nine rare variants in the coding sequence of GUCY1A3 [2]. Two of these variants were found in two extended families with a high prevalence of premature CAD/MI. Seven further rare variants were found in 252 young MI patients. In this study, we aimed to investigate the functional implication of these rare variants found in CAD/MI patients (Table ​(Table1)1) regarding protein level, dimerization capability and enzymatic activity. Table 1 Rare variants of sGC α1 subunit found in MI patients: Two of the investigated α1 variants exhibited significantly decreased protein levels compared to wild type α1. The amount of β1 correlated with those of α1 in all cases. All α1 variants, except for p.Leu163Phefs*24, still dimerized with the β1 subunit, as shown by co-immunoprecipitation. Using radioimmunoassay three of the rare variants demonstrated significantly decreased cGMP amounts at every time point tested (0.5/1/2 min). The activity only in part correlated with the observed protein levels pointing to an effect of the tested variants on enzymatic activity. As we have shown that loss of function-mutations in GUCY1A3 may lead to CAD/MI [2], decreased enzymatic activity might also increase risk. Future studies focus on mRNA abundance and protein degradation to uncover the reason for attenuated activity of the respective variants.

The bamboo fiber is a potential candidate for biomass and power source application. In this study, microfibrillated cellulose (MFC) is prepared from raw fibers of bamboo tree (Bambusa Blumeana J A & J H Schultes) by an alkali treatment at room temperature in association with a bleaching treatment followed by a sulfuric acid hydrolysis. Field-emission scanning electron microscopy (FESEM) images indicated that final products ranged from 20 to 40 nm in diameter. The chemical composition measurement and Fourier transform infrared (FTIR) spectroscopy showed that both hemicellulose and lignin are mostly removed in the MFC. The x-ray diffraction (XRD) results also show that MFC has crystallinity of more than 70%. The thermogravimetric analysis (TGA) curves revealed that cellulose microfibers have a two-step thermal decomposition behavior owing to the attachment of sulfated groups onto the cellulose surface in the hydrolysis process with sulfuric acid. The obtained MFCs may have potential applications in alternative power sources as biomass, in pharmaceutical and optical industries as additives, as well as in composite fields as a reinforcement phase.