Cyanine Dye Coupling Mediates Self-assembly of a pH Sensitive Peptide into Novel 3D Architectures

Synthetic multichromophore systems are of great importance in artificial light harvesting devices, organic optoelectronics, tumor imaging and therapy. Here, we introduce a promising strategy for the construction of self-assembled peptide templated dye stacks based on coupling of a de novo designed pH sensitive peptide with a cyanine dye Cy5 at its N-terminus. Microscopic techniques, in particular cryogenic TEM (cryo-TEM) and cryo-electron tomography technique (cryo-ET), reveal two types of highly ordered three-dimensional assembly structures on the micrometer scale. Unbranched compact layered rods are observed at pH 7.4 and two-dimensional membrane-like assemblies at pH 3.4, both species displaying spectral features of H-aggregates. Molecular dynamics simulations reveal that the coupling of Cy5 moieties promotes the formation of both ultrastructures, whereas the protonation states of acidic and basic amino acid side chains dictates their ultimate three-dimensional organization.

Erythrocytes from patients with ST-elevation myocardial infarction induce cardioprotection via the purinergic P2Y13 receptor and nitric oxide signalling

Background

Red blood cells (RBC) are suggested to act as important mediators in the regulation of cardiovascular function by exporting nitric oxide (NO) bioactivity and ATP under hypoxic/ischemic conditions. In addition, RBCs are known to protect from ischemia-reperfusion injury via the export of NO bioactivity in experimental settings. However, it remains unknown if such beneficial effects of RBCs are protective in patients with acute myocardial infarction.

Purpose

To investigate whether RBCs from patients with ST-elevation myocardial infarction (STEMI) protect against myocardial ischemia-reperfusion injury and whether such effect involves activation of purinergic and NO signalling in the RBCs.

Methods

RBCs were collected from patients with STEMI undergoing primary percutaneous coronary intervention and age- and gender-matched healthy controls. The RBCs were administered into the coronary circulation of isolated Langendorff-perfused rat hearts at the onset of global ischemia for 25 min followed by reperfusion of 60 min. Recovery of left ventricular developed pressure (LVDP) during reperfusion and infarct size were determined. All animal experiments and procedures were performed according to the guidelines by the U.S National Institutes of Health (NIH publication no 85–23, revised 1996). The present study was performed following The Code of Ethics of the World Medical Association outlined in the Declaration of Helsinki of 1975 and revised in 1983 for experiments that involve human subjects.

Results

Administration of RBCs from STEMI patients improved recovery of LVDP and reduced infarct size in hearts subjected to ischemia-reperfusion in comparison with RBCs from healthy controls (Figure 1A, B). Pre-incubation of the RBCs with the NO synthase (NOS) inhibitor L-NAME (Figure 1C, D) and the inhibitor of the NO receptor soluble guanylyl cyclase (sGC) ODQ abolished the cardioprotective effect of RBCs from STEMI patients. The cardioprotective effect was also attenuated by inhibition of cardiac cGMP-dependent protein kinase (PKG). Further, the purinergic P2Y13 receptor antagonist MRS2211 (Figure 1E, F), but not the P1 receptor antagonist 8PT applied to RBCs, attenuated the cardioprotection induced by RBCs from STEMI patients. Moreover, administration of RBCs from healthy subjects pre-incubated with a cell permeable ATP analogue improved post-ischemic recovery of LVDP and reduced infarct size. This cardioprotective effect was abolished by co-incubation of the RBCs with ODQ (Figure 2) and MRS2211.

Conclusion

Our findings demonstrate a novel function of RBCs in patients with STEMI that provides protection against myocardial ischemia-reperfusion injury via the activation of P2Y13 receptor and the NO-sGC pathway in RBCs and cardiac PKG.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Swedish Heart and Lung Foundation; Swedish Research Council

Three-year Clinical Performance of Two Giomer Restorative Materials in Restorations

CLINICAL RELEVANCE

The clinical performance of both conventional and flowable giomer restorative materials was particularly good in Class I restorations after three years of service.

SUMMARY

This study evaluated and compared the clinical performance of a flowable and a conventional giomer restorative material after three years. Forty-four pairs of restorations (total n=88) were placed in Class I cavities with either a flowable giomer (Beautifil Flow Plus F00; Shofu Inc, Kyoto, Japan) or a conventional giomer restorative material (Beautifil II; Shofu Inc) after the application of a dentin adhesive (FL-Bond II; Shofu Inc) and a flowable liner (Beautifil Flow Plus F03; Shofu Inc). After 3 years, 39 pairs of restorations were evaluated with the modified United States Public Health Service criteria, and digital color photographs of restorations were taken at each patient visit. The evaluation parameters were as follows: color match, marginal integrity, marginal discoloration, retention, secondary caries formation, anatomic form, surface texture, and postoperative sensitivity. Evaluations were recorded as a clinically ideal situation (Alpha), a clinically acceptable situation (Bravo), or a clinically unacceptable situation (Charlie). Data were analyzed with Fisher's exact and McNemar tests (α=0.05).None of the restorations showed retention loss, postoperative sensitivity, secondary caries, or color change. The performance of Beautifil II in terms of marginal integrity, marginal discoloration, and surface anatomic form was significantly lower at the 36-month follow-up than at baseline (p=0.007). There were no significant differences between the baseline and 36-month follow-up scores for the other criteria for Beautifil II (p>0.05). No differences were found between the baseline and the 36-month follow-up scores for any of the criteria for Beautifil Flow Plus F00 (p>0.05). No statistically significant difference in overall clinical performance was found between the 2 materials after 36 months (p>0.05).The three-year clinical performance of both restorative materials (Beautifil Flow Plus F00 and Beautifil II) was very good and not significantly different for any of the parameters evaluated.

An exploratory randomised controlled trial evaluating text prompts in Lebanon to encourage health-seeking behaviour for hypertension

AIMS OF THE STUDY

The current study evaluates the effectiveness of an opportunistic mobile screening on the percentage of people who are aware of whether they may be hypertensive (in an observational study) and the effectiveness of reminder prompts on the percentage of people who seek further medical attention (in a randomised controlled trial).

METHODS USED TO CONDUCT THE STUDY

The screening of 1227 participants (529 female) was conducted during the registration period of the 2018 Beirut International Marathon in Lebanon. Next, 266 participants whose screening indicated hypertension (64 Female) were randomly allocated to a treatment group or a control group in a 1:1 fashion. The treatment group received a reminder prompt to seek further medical attention for their potential hypertension and the control group did not. The overt nature of the text message meant that participants in the treatment group could not be blinded to their group allocation. The primary outcome is participants' self-reports of whether they sought further medical attention.

RESULTS OF THE STUDY

For the opportunistic screening, a 25% prevalence rate and a 24% awareness rate of hypertension was indicated. A McNemar analysis suggested that the screening increased participant awareness (X² (N = 1227) = 72.16, P < .001). For the randomised controlled trial, 219 participants provided follow-up data via a phone call (82% retention). A Chi-squared analysis suggested that the reminder prompt successfully encouraged more participants to seek further medical attention, 45.5% treatment group vs 28.0% control group (X² (1, N = 219) = 7.19, P = .007, φ = 0.18).

CONCLUSIONS DRAWN AND CLINICAL IMPLICATIONS

Extra support in the form of a brief reminder message can increase the percentage of people who seek further medical attention after attending an opportunistic screening at a marathon event. The discussion reviews how the results align with previous research, strengths and limitations of the current study, and implications for future research and practice.

Allosteric modulation of the sarcoplasmic reticulum Ca2+ ATPase by thapsigargin via decoupling of functional motions

The sarcoplasmic reticulum Ca2+-ATPase (SERCA) is a widely studied member of the large family of phosphorylation(P)-type ATPase membrane transporters. Ligands and nucleotide binding naturally modulate the conformational space of P-type ATPases through allosteric inter-domain communications. Whereas many inhibitory ATPase ligands act by directly blocking substrate uptake or release, SERCA is a target for thapsigargin (TG), a plant-derived natural product that allosterically inhibits the transport cycle. While thapsigargin's inhibitory effects on SERCA have been widely studied experimentally, the molecular mechanisms underlying these remain incompletely understood. Here, we apply modelling and molecular simulations to probe the effects of TG binding to the major functional states along SERCA's reaction cycle. Our results provide insight into the atomic-level details of the conformational changes induced by TG binding to SERCA, and suggest mechanisms for its effect. Since other P-type ATPases share closely related reaction cycles, our data suggests that similar modulators might exist for these.

P6599Upregulation of protein and gene expression of arginase-1 in patients with ST elevation myocardial infarction

Background

The mechanisms underlying rupture of a coronary atherosclerotic plaque and development of myocardial ischemia-reperfusion injury in ST-elevation myocardial infarction (STEMI) remain unknown. Increased arginase-1 activity leads to reduced nitric oxide production and increased formation of reactive oxygen species due to uncoupling of the endothelial nitric oxide synthase (eNOS). These events lead to endothelial dysfunction, plaque instability and increased susceptibility to ischemia-reperfusion injury in acute myocardial infarction. Experimental studies have shown that arginase-1 expression and activity are increased in atherosclerosis and during myocardial ischemia-reperfusion. Accordingly, inhibition of arginase-1 reduces atherosclerotic lesion development and limits the extent of infarct size during ischemia-reperfusion via an eNOS-dependent mechanism. Furthermore, arginase-1 inhibition improves endothelial function in patients with coronary artery disease but the potential role of arginase-1 in patients with STEMI is poorly understood.

Purpose

The purpose of the current study was to test the hypothesis that arginase-1 is upregulated and correlate to infarct size in STEMI patients.

Methods and results

Two independent cohorts of STEMI patients were included. In cohort 1, plasma and buffy coat leukocytes were collected from 53 STEMI patients at the time of arterial puncture for percutaneous coronary intervention, at 24–48 hours post STEMI and at 3 months post STEMI. Gene expression in leukocytes was determined in 51 patients with Affymetrix Human Transcriptome Array 2.0. In cohort 2, plasma was collected from 82 STEMI patients at admission and at 6 months for determination of plasma arginase-1. These patients underwent cardiac magnetic resonance imaging performed at day 4–7 and at 6 months post STEMI. Plasma arginase-1 levels were quantified with ELISA. Control blood samples were collected from 56 healthy age matched subjects. In cohort 1, ARG1 gene expression was four-fold higher in STEMI patients at admission compared to controls (Figure A). This expression returned to control levels within 3 months. Plasma arginase-1 levels were two times higher in STEMI patients at admission compared to controls, and remained elevated at 24–48 hours and at 3 months post STEMI (Figure B). The increase in plasma arginase-1 in STEMI patients was confirmed in cohort 2 (Figure C). Arginase-1 levels did not correlate with infarct size.

Conclusions

STEMI patients demonstrate increased gene expression and plasma levels of arginase-1 in the acute setting. In contrast to gene expression plasma arginase-1 levels remain significantly elevated over time. The markedly increased expression of arginase-1 already at admission may suggest a mechanistic role of arginase-1 in the development of STEMI. Further studies are needed to elucidate whether increased expression, induction and activity of arginase-1 are contributing factors for the development of STEMI.

P6400Risk for heart failure after acute myocardial infarction, a nationwide report on 73 303 patients with and without diabetes 2012–2017 in the SWEDEHEART-SCAAR registry

Background

Impressive improved one-year survival rates after acute myocardial infarction (AMI) have been achieved the last decades while long-term cardiovascular events still are a challenge particularly when diabetes is present. Recently several glucose lowering drugs with preventive effects on heart failure (HF) and MACE have entered the market however still used in low proportion by cardiologists.

Purpose

To explore the real-life complication rates of HF after AMI in patients with and without diabetes.

Methods

All patients with AMI admitted for coronary angiography in Sweden 2012–2017 were followed for time to first hospitalisation with HF diagnosis (ICD-10 code I50) until December 2017. Kaplan-Meier curves were used to estimate the cumulative heart failure event stratified by previous MI. Hazard ratios (HR) were calculated in a Cox proportional hazard regression model adjusting for age, gender, smoking, creatinine, previous CABG/cancer/dementia/dialysis/hypertension/COPD/renal failure/stroke, year, indication, hospital, angiographic findings, primary decision after angiography, cardiac chock, medications at discharge.

Results

Of 73 303 patients, mean age was 69 years (SD±12), 69% were men and 24% had diabetes. In all, HF occurred in 14% with a higher rate in patients with diabetes than those without (22% vs 12%). The highest HF rates were seen in patients with previous MI (33% if diabetes was present vs. 23% if no diabetes). After adjustments, patients with diabetes without previous MI had about the same HF risk (HR 1.52 [95% CI 1.44–1.61]) as patients without diabetes with previous MI (1.48 [1.40–1.57]) where patients without diabetes and previous MI served as a reference. The same pattern was seen regardless of STEMI/NSTEMI and also after excluding patients with previous HF (n=4567, 6%; Figure; patients with diabetes without previous MI 1.48 [1.40–1.57] and patients without diabetes with previous MI 1.27 [1.19–1.36]).

Conclusion

Heart failure is a common complication after AMI in patients with diabetes, particularly if previous MI, and regardless of previous reported heart failure. Diabetes increases the risk of heart failure by 30–50% compared to those without diabetes. These data indicate the existence of a large diabetes population at heart failure risk after AMI where heart failure protective glucose lowering drugs could be suitable.

Acknowledgement/Funding

The Swedish Heart and Lung foundation, Department of Research and Development Region Kronoberg, the Kamprad Family Foundation

The ESC ACCA EAPCI EORP acute coronary syndrome ST-elevation myocardial infarction registry

Aims 

The Acute Cardiac Care Association (ACCA)–European Association of Percutaneous Coronary Intervention (EAPCI) Registry on ST-elevation myocardial infarction (STEMI) of the EurObservational programme (EORP) of the European Society of Cardiology (ESC) registry aimed to determine the current state of the use of reperfusion therapy in ESC member and ESC affiliated countries and the adherence to ESC STEMI guidelines in patients with STEMI.

Methods and results 

Between 1 January 2015 and 31 March 2018, a total of 11 462 patients admitted with an initial diagnosis of STEMI according to the 2012 ESC STEMI guidelines were enrolled. Individual patient data were collected across 196 centres and 29 countries. Among the centres, there were 136 percutaneous coronary intervention centres and 91 with cardiac surgery on-site. The majority of centres (129/196) were part of a STEMI network. The main objective of this study was to describe the demographic, clinical, and angiographic characteristics of patients with STEMI. Other objectives include to assess management patterns and in particular the current use of reperfusion therapies and to evaluate how recommendations of most recent STEMI European guidelines regarding reperfusion therapies and adjunctive pharmacological and non-pharmacological treatments are adopted in clinical practice and how their application can impact on patients’ outcomes. Patients will be followed for 1 year after admission.

Conclusion 

The ESC ACCA-EAPCI EORP ACS STEMI registry is an international registry of care and outcomes of patients hospitalized with STEMI. It will provide insights into the contemporary patient profile, management patterns, and 1-year outcome of patients with STEMI.

The antioxidant resveratrol acts as a non-selective adenosine receptor agonist

Resveratrol (RSV) is a natural polyphenolic antioxidant with a proven protective role in several human diseases involving oxidative stress, although the molecular mechanism underlying this effect remains unclear. The present work tried to elucidate the molecular mechanism of RSV's role on signal transduction modulation. Our biochemical analysis, including radioligand binding, real time PCR, western blotting and adenylyl cyclase activity, and computational studies provide insights into the RSV binding pathway, kinetics and the most favored binding pose involving adenosine receptors, mainly A_2A subtype. In this study, we show that RSV target adenosine receptors (AdoRs), affecting gene expression, receptor levels, and the downstream adenylyl cyclase (AC)/PKA pathway. Our data demonstrate that RSV activates AdoRs. Moreover, RSV activate A_2A receptors by directly binding to the classical orthosteric binding site. Intriguingly, RSV-induced receptor activation can stimulate or inhibit AC activity depending on concentration and exposure time. Such subtle and multifaceted regulation of the AdoRs/AC/PKA pathway might contribute to the protective role of RSV. Our findings suggest that RSV molecular action is mediated, at least in part, by activation of adenosine receptors and create the opportunity to interrogate the therapeutic use of RSV in pathological conditions involving AdoRs, such as Alzheimer.

Binding, Thermodynamics, and Selectivity of a Non-peptide Antagonist to the Melanocortin-4 Receptor

The melanocortin-4 receptor (MC4R) is a potential drug target for treatment of obesity, anxiety, depression, and sexual dysfunction. Crystal structures for MC4R are not yet available, which has hindered successful structure-based drug design. Using microsecond-scale molecular-dynamics simulations, we have investigated selective binding of the non-peptide antagonist MCL0129 to a homology model of human MC4R (hMC4R). This approach revealed that, at the end of a multi-step binding process, MCL0129 spontaneously adopts a binding mode in which it blocks the agonistic-binding site. This binding mode was confirmed in subsequent metadynamics simulations, which gave an affinity for human hMC4R that matches the experimentally determined value. Extending our simulations of MCL0129 binding to hMC1R and hMC3R, we find that receptor subtype selectivity for hMC4R depends on few amino acids located in various structural elements of the receptor. These insights may support rational drug design targeting the melanocortin systems.

A New Lebanese Medication Adherence Scale: Validation in Lebanese Hypertensive Adults

BACKGROUND

A new Lebanese scale measuring medication adherence considered socioeconomic and cultural factors not taken into account by the eight-item Morisky Medication Adherence Scale (MMAS-8). Objectives were to validate the new adherence scale and its prediction of hypertension control, compared to MMAS-8, and to assess adherence rates and factors.

METHODOLOGY

A cross-sectional study, including 405 patients, was performed in outpatient cardiology clinics of three hospitals in Beirut. Blood pressure was measured, a questionnaire filled, and sodium intake estimated by a urine test. Logistic regression defined predictors of hypertension control and adherence.

RESULTS

54.9% had controlled hypertension. 82.4% were adherent by the new scale, which showed good internal consistency, adequate questions (KMO coefficient = 0.743), and four factors. It predicted hypertension control (OR = 1.217; p value = 0.003), unlike MMAS-8, but the scores were correlated (ICC average measure = 0.651; p value < 0.001). Stress and smoking predicted nonadherence.

CONCLUSION

This study elaborated a validated, practical, and useful tool measuring adherence to medications in Lebanese hypertensive patients.

Multiple Binding Sites Contribute to the Mechanism of Mixed Agonistic and Positive Allosteric Modulators of the Cannabinoid CB1 Receptor

The cannabinoid CB1 receptor (CB1R) is an abundant metabotropic G-protein-coupled receptor that has been difficult to address therapeutically because of CNS side effects exerted by orthosteric drug candidates. Recent efforts have focused on developing allosteric modulators that target CB1R. Compounds from the recently discovered class of mixed agonistic and positive allosteric modulators (Ago-PAMs) based on 2-phenylindoles have shown promising functional and binding properties as CB1R ligands. Here, we identify binding modes of both the CP 55,940 agonist and GAT228, a 2-phenylindole allosteric modulator, by using our metadynamics simulation protocol, and quantify their affinity and cooperativity by atomistic simulations. We demonstrate the involvement of multiple adjunct binding sites in the Ago-PAM characteristics of the 2-phenylindole modulators and explain their ability to compete with orthosteric agonists at higher concentrations. We validate these results experimentally by showing the contribution of multiple sites on the allosteric binding of ZCZ011, another homologous member of the class, together with the orthosteric agonist.

Molecular Mechanisms of Biased and Probe-Dependent Signaling at CXC-Motif Chemokine Receptor CXCR3 Induced by Negative Allosteric Modulators

Our recent explorations of allosteric modulators with improved properties resulted in the identification of two biased negative allosteric modulators, BD103 (N-1-{[3-(4-ethoxyphenyl)-4-oxo-3,4-dihydropyrido[2,3-d]pyrimi-din2yl]ethyl}-4-(4-fluorobutoxy)-N-[(1-methylpiperidin-4-yl)methyl}]butanamide) and BD064 (5-[(N-{1-[3-(4-ethoxyphenyl)-4-oxo-3,4-dihydropyrido[2,3-d]pyrimidin-2-yl]ethyl-2-[4-fluoro-3-(trifluoromethyl)phenyl]acetamido)methyl]-2-fluorophenyl}boronic acid), that exhibited probe-dependent inhibition of CXC-motif chemokine receptor CXCR3 signaling. With the intention to elucidate the structural mechanisms underlying their selectivity and probe dependence, we used site-directed mutagenesis combined with homology modeling and docking to identify amino acids of CXCR3 that contribute to modulator binding, signaling, and transmission of cooperativity. With the use of allosteric radioligand RAMX3 ([³H]N-{1-[3-(4-ethoxyphenyl)-4-oxo-3,4-dihydropyrido[2,3-d]pyrimidin-2-yl]ethyl}-2-[4-fluoro-3-(trifluoromethyl)phenyl]-N-[(1-methylpiperidin-4-yl)methyl]acetamide), we identified that F131^3.32 and Y308^7.43 contribute specifically to the binding pocket of BD064, whereas D186^4.60 solely participates in the stabilization of binding conformation of BD103. The influence of mutations on the ability of negative allosteric modulators to inhibit chemokine-mediated activation (CXCL11 and CXCL10) was assessed with the bioluminescence resonance energy transfer-based cAMP and β-arrestin recruitment assay. Obtained data revealed complex molecular mechanisms governing biased and probe-dependent signaling at CXCR3. In particular, F131^3.32, S304^7.39, and Y308^7.43 emerged as key residues for the compounds to modulate the chemokine response. Notably, D186^4.60, W268^6.48, and S304^7.39 turned out to play a role in signal pathway selectivity of CXCL10, as mutations of these residues led to a G protein-active but β-arrestin-inactive conformation. These diverse effects of mutations suggest the existence of ligand- and pathway-specific receptor conformations and give new insights in the sophisticated signaling machinery between allosteric ligands, chemokines, and their receptors, which can provide a powerful platform for the development of new allosteric drugs with improved pharmacological properties.

Bimetallic gold(i) complexes of photoswitchable phosphines: synthesis and uses in cooperative catalysis

The first photoswitchable bimetallic gold catalysts based on an azobenzene backbone have been synthesized and their catalytic properties have been investigated.

THE EFFECT OF SALBUTAMOL ON PGC-1 α AND GLUT4 mRNA EXPRESSION IN THE LIVER AND MUSCLE OF ELDERLY DIABETIC MICE

Background

Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) plays an important role in the regulation of cellular energy metabolism, and it is involved in obesity and type 2 diabetes mellitus (T2DM). Its expression is elevated in the liver of T2DM mouse models. Literature reports show that chronic β2 stimulation improved insulin sensitivity in T2DM.

Objectives

We aimed to test the hypotheses that chronic β2 stimulation-induced improvement in insulin sensitivity involves changes in the expression of PGC-1α and glucose transporter 4 (GLUT4).

Animals and Methods

We fed a locally inbred, 8 months old mice, a high fat diet (HFD) to induce diabetes. These mice gained weight and became insulin resistant. The β2 agonist salbutamol had a beneficial effect on both glucose tolerance and insulin sensitivity after 4 weeks.

Results

Salbutamol beneficial effect persisted after 4 weeks of its discontinuation. HFD caused an up regulation of the hepatic PGC-1 α expression by 5.23 folds (P< 0.041) and salbutamol reversed this effect and caused a down regulation by 30.3 folds (P< 0.0001). PGC-1 α and GLUT4 expression in the muscle was not affected by salbutamol (P> 0.05).

Conclusion

Down regulation of the liver's PGC-1 α contributes to the beneficial effect of the chronic β2 stimulation on glucose tolerance and insulin sensitivity in T2DM mice.

An Efficient Metadynamics-Based Protocol To Model the Binding Affinity and the Transition State Ensemble of G-Protein-Coupled Receptor Ligands

A generally applicable metadynamics scheme for predicting the free energy profile of ligand binding to G-protein-coupled receptors (GPCRs) is described. A common and effective collective variable (CV) has been defined using the ideally placed and highly conserved Trp6.48 as a reference point for ligand-GPCR distance measurement and the common orientation of GPCRs in the cell membrane. Using this single CV together with well-tempered multiple-walker metadynamics with a funnel-like boundary allows an efficient exploration of the entire ligand binding path from the extracellular medium to the orthosteric binding site, including vestibule and intermediate sites. The protocol can be used with X-ray structures or high-quality homology models (based on a high-quality template and after thorough refinement) for the receptor and is universally applicable to agonists, antagonists, and partial and reverse agonists. The root-mean-square error (RMSE) in predicted binding free energies for 12 diverse ligands in five receptors (a total of 23 data points) is surprisingly small (less than 1 kcal mol^-1). The RMSEs for simulations that use receptor X-ray structures and homology models are very similar.

Investigating allosteric effects on the functional dynamics of β2-adrenergic ternary complexes with enhanced-sampling simulations

Signalling by G-protein coupled receptors usually occurs via ternary complexes formed under cooperative binding between the receptor, a ligand and an intracellular binding partner (a G-protein or β-arrestin). While a global rational for allosteric effects in ternary complexes would be of great help in designing ligands with specific effects, the paucity of structural data for ternary complexes with β-arrestin, together with the intrinsic difficulty of characterizing the dynamics involved in the allosteric coupling, have hindered the efforts to devise such a model. Here we have used enhanced-sampling atomistic molecular-dynamics simulations to investigate the dynamics and complex formation mechanisms of both β-arrestin- and Gs-complexes with the β2-adrenergic receptor (ADRB2) in its apo-form and in the presence of four small ligands that exert different allosteric effects. Our results suggest that the structure and dynamics of arrestin-ADRB2 complexes depend strongly on the nature of the small ligands. The complexes exhibit a variety of different coupling orientations in terms of the depth of the finger loop in the receptor and activation states of ADRB2. The simulations also allow us to characterize the cooperativity between the ligand and intracellular binding partner (IBP). Based on the complete and consistent results, we propose an experimentally testable extended ternary complex model, where direction of the cooperative effect between ligand and IBP (positive or negative) and its magnitude are predicted to be a characteristic of the ligand signaling bias. This paves the avenue to the rational design of ligands with specific functional effects.

Mortality and extent of coronary artery disease in 2776 patients with type 1 diabetes undergoing coronary angiography: A nationwide study

Background In a modern perspective there is limited information on mortality by affected coronary vessels assessed by coronary angiography in patients with type 1 diabetes. The aim of the present study was to characterise distribution of coronary artery disease and impact on long-term mortality in patients with type 1 diabetes undergoing coronary angiography. Design The design of this research was a nationwide population-based cohort study. Methods Individuals ( n = 2776) with type 1 diabetes undergoing coronary angiography 2001-2013 included in the Swedish National Diabetes Registry and Swedish Coronary Angiography and Angioplasty Registry were followed for mortality until 31 December 2013 (mean 7.1 years). In 79% the indication was stable or acute coronary artery disease. Coronary artery disease was categorised into normal (21%), one- (23%), two- (18%), three- (29%) and left main-vessel disease (8%). Results Mean age was 57 years and 58% were male. Mean diabetes duration was 35 years, glycated haemoglobin was 67 mmol/mol and 44% had normal or one-vessel disease. In multivariate Cox proportional analyses hazard ratio for mortality compared with normal findings was 1.09 (95% confidence interval 0.80-1.48) for one, 1.43 (1.05-1.94) for two, 1.47 (1.10-1.96) for three and 1.90 (1.35-2.68) for left main-vessel disease. Renal failure 2.29 (1.77-2.96) and previous heart failure 1.76 (1.46-2.13) were highly associated with mortality. Standard mortality ratio the first year was 5.55 (4.65-6.56) and decreased to 2.80 (2.18-3.54) after five years. Conclusions In patients with type 1 diabetes referred for coronary angiography mortality is influenced by numbers of affected coronary vessels. The overall mortality rate was higher compared with the general population. These results support early intensive prevention of coronary artery disease in this population.

Improved slow magnetic relaxation in optically pure helicene-based DyIII single molecule magnets

Racemic and optically pure [Dy(hfac)₃(L)] complexes with L = 3-(2-pyridyl)-4-aza[6]-helicene have been synthesized and characterized.

[Substance use among Lebanese university students: prevalence and associated factors]

Scientific research on use and misuse of substances in Lebanon is scarce. This study aimed to evaluate the rate of use and abuse of substances among Lebanese youth and identify the determinants and risk factors behind these behaviours. An observational survey was conducted on 1945 university students selected from the different faculties of the Lebanese University and other private universities. A self-administered questionnaire based on ASSIST (Alcohol, Smoking and Substance Involvement Screening Test) was administered. The prevalence of ever consuming alcohol was 20.9%. Cannabis (12.3%) and tranquilizers (11%) had the highest rates of ever use among the drugs, whereas cocaine (3.3%) and hallucinogens (3.6%) had the lowest rates. Smoking cigarettes and waterpipes, going out at night, peer pressure and having no specific leisure time activity were associated with problematic substance use, while a better relationship with parents, reading and working were inversely associated with use. There is a high prevalence of substance use among university students in Lebanon. Multidisciplinary support for addicted students is needed to meet their diverse needs.

[Asthma, indoor and outdoor air pollution: A pilot study in Lebanese school teenagers]

INTRODUCTION

Many studies have demonstrated that outdoor pollution might exacerbate respiratory symptoms and childhood asthma. Our objective was to evaluate the relationship between asthma and outdoor and indoor pollution.

METHODS

We undertook a survey in May-June 2012 about schoolchildren aged 12-19 years in six Lebanese schools. This combined the International Study of Asthma and Allergies in Childhood (ISAAC) standardized questionnaire with other questions addressing outdoor and indoor exposure.

RESULTS

Among 717 subjects (response rate 71.7%), 4.5% had physician-diagnosed asthma, 34.7% had probable asthma and 60.8% were asymptomatic. Exposure to indoor contaminants was positively associated to asthma. The risk for asthma was higher in those residing near heavy road traffic (ORa=4.30 [95% CI 1.45-12.71], P<0.05), those previously exposed to fire (ORa=1.84 [95% CI 1.01-3.36]), and those exposed to smog (ORa=4.15 [95% CI 1.42-12.12]). Airing the house in the morning or in case of indoor smoking had a protective effect against asthma.

CONCLUSION

These results suggest that the risks of asthma or having respiratory symptoms are not only related to indoor pollution but also to outdoor pollution especially from road traffic.

Spectroscopic studies of keto–enol tautomeric equilibrium of azo dyes

Keto–enol tautomeric equilibrium of an azo dye is shifted to the keto form as the solvent polarity is increased.

Exploring the free-energy landscape of carbohydrate-protein complexes: development and validation of scoring functions considering the binding-site topology

Carbohydrates play a key role in a variety of physiological and pathological processes and, hence, represent a rich source for the development of novel therapeutic agents. Being able to predict binding mode and binding affinity is an essential, yet lacking, aspect of the structure-based design of carbohydrate-based ligands. We assembled a diverse data set comprising 273 carbohydrate-protein crystal structures with known binding affinity and evaluated the prediction accuracy of a large collection of well-established scoring and free-energy functions, as well as combinations thereof. Unfortunately, the tested functions were not capable of reproducing binding affinities in the studied complexes. To simplify the complex free-energy surface of carbohydrate-protein systems, we classified the studied proteins according to the topology and solvent exposure of the carbohydrate-binding site into five distinct categories. A free-energy model based on the proposed classification scheme reproduced binding affinities in the carbohydrate data set with an r(2) of 0.71 and root-mean-squared-error of 1.25 kcal/mol (N = 236). The improvement in model performance underlines the significance of the differences in the local micro-environments of carbohydrate-binding sites and demonstrates the usefulness of calibrating free-energy functions individually according to binding-site topology and solvent exposure.

Homocysteine and other cardiovascular risk factors in patients with lichen planus

BACKGROUND

Chronic inflammation was found to play an important role in the development of cardiovascular risk factors. Homocysteine (Hcy) and fibrinogen have been identified as a major independent risk factor for cardiovascular disease. Lichen planus is assumed to be closely related to dyslipidaemia. Several cytokines involved in lichen planus pathogenesis, could explain its association with dyslipidaemia. Also chronic inflammation with lichen planus has been suggested as a component of the metabolic syndrome.

OBJECTIVE

The aim of this study was to detect a panel of cardiovascular risk factors in patients of lichen planus.

PATIENTS AND METHODS

This study was done on 40 patients of lichen planus and 40 healthy controls. All patients and controls were subjected to clinical examination. Serum levels of homocysteine, fibrinogen and high-sensitive C-reactive protein (hs-CRP) were measured by enzyme-linked immunosorbent assay technique (ELISA). Metabolic syndrome parameters including anthropometric measures, lipid profiles, blood sugar and blood pressure were studied.

RESULTS

Patients with lichen planus showed significant association with metabolic syndrome parameters than controls (P < 0.001). Serum homocysteine, fibrinogen and hs-CRP were significantly higher in lichen planus patients than controls (P < 0.001). Serum homocysteine correlated with both serum hs-CRP and serum fibrinogen. However, there was no correlation between serum levels of homocysteine and fibrinogen with any metabolic syndrome criteria and related disorders except for a negative correlation of fibrinogen with high-density lipoprotein (HDL).

CONCLUSION

In the present work, patients with lichen planus were found to have higher makers of both metabolic and cardiovascular risk factors in relation to controls most probably due to long standing inflammation.

Long-term mortality in patients with type 2 diabetes undergoing coronary angiography: the impact of glucose-lowering treatment

AIMS/HYPOTHESIS

The aim of this study was to analyse whether the increased mortality rates observed in insulin-treated patients with type 2 diabetes and coronary artery disease are explained by comorbidities and complications.

METHODS

A retrospective analysis of data from two Swedish registries of type 2 diabetic patients (n = 12,515) undergoing coronary angiography between the years 2001 and 2009 was conducted. The association between glucose-lowering treatment and long-term mortality was studied after extensive adjustment for cardiovascular- and diabetes-related confounders. Patients were classified into four groups, according to glucose-lowering treatment: diet alone; oral therapy alone; insulin in combination with oral therapy; and insulin alone.

RESULTS

After a mean follow-up time of 4.14 years, absolute mortality rates for patients treated with diet alone, oral therapy alone, insulin in combination with oral therapy and insulin alone were 19.2%, 17.4%, 22.9% and 28.1%, respectively. Compared with diet alone, insulin in combination with oral therapy (HR 1.27; 95% CI 1.12, 1.43) and insulin alone (HR 1.62; 95% CI 1.44, 1.83) were associated with higher mortality rates. After adjustment for baseline differences, insulin in combination with oral glucose-lowering treatment (HR 1.22; 95% CI 1.06, 1.40; p < 0.005) and treatment with insulin only (HR 1.17; 95% CI 1.02, 1.35; p < 0.01) remained independent predictors for long-term mortality.

CONCLUSIONS/INTERPRETATION

Type 2 diabetes patients treated with insulin and undergoing coronary angiography have a higher long-term mortality risk after adjustment for measured confounders. Further research is needed to evaluate the optimal glucose-lowering treatment for these high-risk patients.

Clinicopathological and immunological studies on toxoids vaccine as a successful alternative in controlling clostridial infection in broilers

The present study was conducted to evaluate the efficacy and safety of three vaccination regimes of Clostridium perfringens (C. perfringens) type A, C and combined A&C toxoids based on their clinical signs and immunological effects. The vaccines were administered two times at two weeks interval (7 & 21 days old), then the birds were challenged (35 days old) with virulent strains of C. perfringens type A, C and combined A&C. Blood samples were taken one week after the first and second vaccination as well as after challenge. The evaluated parameters in this study included: clinical signs, gross intestinal lesions, complete blood count (CBC), serum protein, liver profiles, and enzyme-linked immunosorbent assay (ELISA) test for detecting serum antibody titers. The results revealed that immunization of broilers with C. perfringens type A, C and combined A&C toxoids resulted in a significant decrease in numbers of chickens with intestinal lesions particularly with the A&C toxoids vaccine. Results of the CBC values were significantly increased in all treated groups and challenged groups. Total leukocytic count decreased in challenged non vaccinated group while increased in challenged vaccinated birds. Results of biochemical assays implicated that there were a significant increase in serum protein and liver profiles. ELISA results explored a significant increase in antibody titers after immunization of broilers with C. perfringens type A, C and combined A&C toxoids particularly after the second dose of vaccination. We concluded that immunization of broilers with toxoid vaccines particularly the combined type A & C is safe, well-tolerated and can protect broiler chickens against necrotic enteritis particularly after the second booster dose of the vaccine.

Prevalence and determinants of fecal incontinence in premenopausal women in an Arabian community

OBJECTIVES

The aim of this study was to determine the prevalence, awareness and determinants of fecal incontinence among Qatari women.

METHOD

In the cross-sectional community-based study in primary health-care centers, using a multistage sampling design, a representative sample of randomly selected 776 Qatari women aged from 40 to 48 years were approached from January to August 2007; only 596 women, with a response rate of 76.8%, gave consent and were included in the analysis. Participants completed a questionnaire assessing fecal incontinence in the previous 12 months and health care-seeking behavior for fecal symptoms. Fecal incontinence, determined by self-report, was categorized by frequency. Females reported the level of bother of fecal incontinence and their general quality of life. Potential risk factors were assessed by self-report, interview, physical examination, and record review.

RESULTS

Of the studied Qatari women, 62 (10.4%) were found to have fecal incontinence. There was a significant difference between fecal incontinent and continent groups with regard to menopause (p < 0.0001), surgical repair of genital prolapse (p < 0.0001) and constipation (p < 0.0001). Only 31 incontinent patients (50%) had sought medical advice. Of the fecal incontinent women, 77.4% felt embarrassment in consulting a doctor and 77.4% believed their condition was worth reporting to a doctor. Aging (51.6%) was the major cause of fecal incontinence in women, followed by childbirth (40.3%), then menopause (25.8%) and lastly paralysis (14.5%). Most of the sufferers were troubled by their inability to pray (64.5%). Their relationship with their husband (41.9%) was the significant consequence for fecal incontinent Qatari women (p = 0.02); 37.1% isolated themselves from social activities and going out to shop.

CONCLUSIONS

The study findings revealed that fecal incontinence is a common symptom among women in the community. There was a correlation between fecal incontinence and menopause. Overall, most of the fecal incontinent women reported that fecal incontinence significantly affected quality of life and only half of the studied women had consulted a physician for the symptom.

Ultrasound Prediction of Fetal Macrosomia in Diabetic Women and its Effect on the Route of Delivery and the Outcome of Pregnancy

Objective: The purpose of this study is to review the maternal and neonatal outcome in pregnant diabetic women given a trial of labor and delivered macrosomic infants (>4000 grams) and to assess the accuracy of birth weight prediction by ultrasound examination at term.

Methods: One hundred and twenty-nine charts of pregnant diabetic women were reviewed, sixty eight women were given a trial of labor and delivered macrosomic fetuses (>4000 grams), fifty of them had vaginal delivery and the other eighteen had caesarean delivery. In the other group, 61 patients delivered by elective caesarean section, for 41 of them the indication was fetal macrosomia (>4000 grams) as estimated by ultrasound examination and in the other 20, it was due to clinical estimation of big baby. Maternal and neonatal complications were reviewed in each group. Maternal complications included lacerations, hemorrhage and infection and the neonatal complications evaluated were shoulder dystocia and associated birth trauma, asphyxia, and mortality. The accuracy of ultrasound in estimating fetal weight was also evaluated.

Results: Sixty eight (52.7%) women attempted a trial of labor; 73.5% delivered vaginally and 26.5% had a caesarean delivery. All, except two, had macrosomic fetuses (>4000 grams). Only one woman, of those who delivered vaginally, had postpartum hemorrhage due to atonic uterus. The incidence of shoulder dystocia for infants weighing 4000-4499 grams was 6.3% and those infants had the same incidence (6.3%) of brachial plexus injury. There was no perinatal asphyxia or perinatal mortality among those infants who were delivered vaginally. There were no maternal complications for women who had caesarean delivery after labor (18 patients) but there was perinatal asphyxia in two infants who were treated properly without any neurological sequele. Elective caesarean delivery was performed in 47.3% of the study population. There were no neonatal complications or perinatal mortality in this group of patients and only one woman had wound infection. The sonographic prediction of fetal weight was accurate in 52.4% of the cases. The over estimation was in 50.8% of the estimated fetal weights and 49.2% of them were underestimated when compared to actual birth weights.

Conclusions: Caution should be taken in the use of sonographic estimations of fetal weight to guide obstetric decisions concerning labor and delivery. Special consideration should be given to diabetic patients having fetuses with estimatedfetal weights between 4000 and 4500 grams. Flexibility in the management of these patients is best, taking in consideration their previous obstetric performance and if the estimated fetal weight is closer to 4500grams than to 4000 grams, it is perhaps, better to proceed to a primary caesarean delivery.