Accurate and Efficient SAXS/SANS Implementation Including Solvation Layer Effects Suitable for Molecular Simulations

Small-angle X-ray and neutron scattering (SAXS/SANS) provide valuable insights into the structure and dynamics of biomolecules in solution, complementing a wide range of structural techniques, including molecular dynamics simulations. As contrast-based methods, they are sensitive not only to structural properties but also to solvent-solute interactions. Their use in molecular dynamics simulations requires a forward model that should be as fast and accurate as possible. In this work, we demonstrate the feasibility of calculating SAXS and SANS intensities using a coarse-grained representation consisting of one bead per amino acid and three beads per nucleic acid, with form factors that can be corrected on the fly to account for solvation effects at no additional computational cost. By coupling this forward model with molecular dynamics simulations restrained with SAS data, it is possible to determine conformational ensembles or refine the structure and dynamics of proteins and nucleic acids in agreement with the experimental results. To assess the robustness of this approach, we applied it to gelsolin, for which we acquired SAXS data on its closed state, and to a UP1-microRNA complex, for which we used previously collected measurements. Our hybrid-resolution small-angle scattering (hySAS) implementation, being distributed in PLUMED, can be used with atomistic and coarse-grained simulations using diverse restraining strategies.

Collateral presence and extent do not predict myocardial viability and ischemia in chronic total occlusions: A stress-CMR study

BACKGROUND

Well-developed collaterals are assumed as a marker of viability and ischemia in chronic total occlusions (CTO). We aim to correlate viability and ischemia with collateral presence and extent in CTO patients by cardiac magnetic resonance (CMR).

METHODS

Multicentre study of 150 CTO patients undergoing stress-CMR, including adenosine if normal systolic function, high-dose-dobutamine for patients with akinetic/>2 hypokinetic segments and EF ≥35%, otherwise low-dose-dobutamine (LDD); all patients underwent late gadolinium enhancement (LGE) imaging. Viability was defined as mean LGE transmurality ≤50% for adenosine, as functional improvement for dobutamine-stress-test, ischemia as ≥1.5 segments with perfusion defects outside the scar zone.

RESULTS

Rentrop 3/CC 2 defined well-developed (WD, n = 74) vs poorly-developed collaterals (PD, n = 76). Viability was equally prevalent in WD vs PD: normo-functional myocardium with ≤50% LGE in 52% vs 58% segments, p = 0.76, functional improvement by LDD in 48% vs 52%, p = 0.12. Segments with none, 1-25%,26-50%,51-75% LGE showed viability by LDD in 90%,84%,81%,61% of cases, whilst in 12% if 76-100% LGE (p < 0.01). There was no difference in WD vs PD for ischemia presence (74% vs 75%, p = 0.99) and extent (2.7 vs 2.8 segments, p = 0.77).

CONCLUSIONS

In a large cohort of CTO patients, presence and extent of collaterals did not predict viability and ischemia by stress-CMR. Scar extent up to 75% LGE was still associated with viability, whereas ischemia was undetectable in 25% of patients, suggesting that the assessment of CTO patients with CMR would lead to a more comprehensive evaluation of viability and ischemia to guide revascularization.

Conformational switch and multiple supramolecular structures of a newly identified self-assembling protein-mimetic peptide from Pseudomonas aeruginosa YeaZ protein

Protein-mimetic peptides (PMPs) are shorter sequences of self-assembling proteins, that represent remarkable building blocks for the generation of bioinspired functional supramolecular structures with multiple applications. The identification of novel aminoacidic sequences that permit the access to valuable biocompatible materials is an attractive area of research. In this work, in silico analysis of the Pseudomonas aeruginosa YeaZ protein (PaYeaZ) led to the identification of a tetradecapeptide that represents the shortest sequence responsible for the YeaZ-YeaZ dimer formation. Based on its sequence, an innovative 20-meric peptide, called PMP-2, was designed, synthesized, and characterized in terms of secondary structure and self-assembly properties. PMP-2 conserves a helical character and self-assembles into helical nanofibers in non-polar solvents (DMSO and trifluoroethanol), as well as in dilute (0.5 mM) aqueous solutions. In contrast, at higher concentrations (>2 mM) in water, a conformational transition from α-helix to β-sheet occurs, which is accompanied by the Protein-mimetic peptide aggregation into 2D-sheets and formation supramolecular gel in aqueous environment. Our findings reveal a newly identified Protein-mimetic peptide that could turn as a promising candidate for future material applications.

Rational Design of a Peptidomimetic Inhibitor of Gelsolin Amyloid Aggregation

Gelsolin amyloidosis (AGel) is characterized by multiple systemic and ophthalmic features resulting from pathological tissue deposition of the gelsolin (GSN) protein. To date, no cure is available for the treatment of any form of AGel. More than ten single-point substitutions in the GSN gene are responsible for the occurrence of the disease and, among them, D187N/Y is the most widespread variant. These substitutions undergo an aberrant proteolytic cascade, producing aggregation-prone peptides of 5 and 8 kDa, containing the Gelsolin Amyloidogenic Core, spanning residues 182-192 (GAC_182-192). Following a structure-based approach, we designed and synthesized three novel sequence-specific peptidomimetics (LB-5, LB-6, and LB-7) built on a piperidine-pyrrolidine unnatural amino acid. LB-5 and LB-6, but not LB-7, efficiently inhibit the aggregation of the GAC_182-192 amyloidogenic peptides at sub-stoichiometric concentrations. These peptidomimetics resulted also effective in vivo, in a C. elegans-based assay, in counteracting the proteotoxicity of aggregated GAC_182-192. These data pave the way to a novel pharmacological strategy against AGel and also validate a toolbox exploitable in other amyloidogenic diseases.

Protein Crystallization of Two Recombinant Lpt Proteins

The prerequisite for 3D structure determination of macromolecules via X-ray crystallography is well-ordered, diffracting crystals. Here, we report the recombinant production, biophysical/biochemical protein sample characterization, and vapor diffusion sitting drop crystallization protocols for two lipopolysaccharide transport proteins: LptH from Pseudomonas aeruginosa (Pa-LptH) and an inactive LptC mutant (G153R) from Escherichia coli (EcLptC_24-191G153R).

A novel hotspot of gelsolin instability triggers an alternative mechanism of amyloid aggregation

Gelsolin comprises six homologous domains, named G1 to G6. Single point substitutions in this protein are responsible for AGel amyloidosis, a hereditary disease causing progressive corneal lattice dystrophy, cutis laxa, and polyneuropathy. Although several different amyloidogenic variants of gelsolin have been identified, only the most common mutants present in the G2 domain have been thoroughly characterized, leading to clarification of the functional mechanism. The molecular events underlying the pathological aggregation of 3 recently identified mutations, namely A551P, E553K and M517R, all localized at the interface between G4 and G5, are here explored for the first time. Structural studies point to destabilization of the interface between G4 and G5 due to three structural determinants: β-strand breaking, steric hindrance and/or charge repulsion, all implying impairment of interdomain contacts. Such rearrangements decrease the temperature and pressure stability of gelsolin but do not alter its susceptibility to furin cleavage, the first event in the canonical aggregation pathway. These variants also have a greater tendency to aggregate in the unproteolysed forms and exhibit higher proteotoxicity in a C. elegans-based assay. Our data suggest that aggregation of G4G5 variants follows an alternative, likely proteolysis-independent, pathway.

Sex differences in treatment strategy for coronary artery aneurysms: Insights from the international Coronary Artery Aneurysm Registry

Introduction

Sex disparities exist in coronary artery disease (CAD) in terms of risk profile, clinical management and outcome. It is unclear if differences are also present in coronary aneurysms, a rare variant of CAD.

Methods

Patients were selected from the international Coronary Artery Aneurysm Registry (CAAR; ClinicalTrials.gov: NCT02563626), and differences between groups were analysed according to sex. The CAAR database is a prospective multicentre registry of 1565 patients with coronary aneurysms (336 females). Kaplan-Meier method was used for event-free survival analysis for death, major adverse cardiac events (MACE: composite endpoint of death, heart failure and acute coronary syndrome) and bleeding.

Results

Female patients were older, were more often hypertensive and less frequently smoker. They were treated conservatively more often compared to male patients and received significantly less frequently aspirin (92% vs 88%, p = 0.002) or dual antiplatelet therapy (DAPT) (67% vs 58%, p = 0.001) at discharge. Median DAPT duration was also shorter (3 vs 9 months, p = 0.001). Kaplan-Meier analysis revealed no sex differences in death, MACE or bleeding during a median follow-up duration of 37 months, although male patients did experience acute coronary syndrome (ACS) more often during follow-up (15% vs 10%, p = 0.015).

Conclusions

These CAAR findings showed a comparable high-risk cardiovascular risk profile for both sexes. Female patients were treated conservatively more often and received DAPT less often at discharge, with a shorter DAPT duration. ACS was more prevalent among male patients; however, overall clinical outcome was not different between male and female patients during follow-up.

Clinical and Histopathological Features of Gelsolin Amyloidosis Associated with a Novel GSN Variant p.Glu580Lys

Simple Summary

Gelsolin amyloidosis is a rare autosomal dominant genetic disease, which typically affects the cornea, skin and sometimes other organ systems and is caused by mutations in a gene coding for gelsolin protein (GSN). We describe a novel mutation of GSN gene, p.Glu580Lys, associated with gelsolin amyloidosis in six members of a two-generation family, who exhibited lattice corneal dystrophy, loose facial skin and irregular heart rhythm. In one patient we reported optic nerve impairment, which is possibly a novel feature associated with gelsolin amyloidosis.

Abstract

Gelsolin amyloidosis typically presents with corneal lattice dystrophy and is most frequently associated with pathogenic GSN variant p.Asp214Asn. Here we report clinical and histopathological features of gelsolin amyloidosis associated with a novel GSN variant p.Glu580Lys. We studied DNA samples of seven members of a two-generation family. Exome sequencing was performed in the proband, and targeted Sanger sequencing in the others. The heterozygous GSN variant p.Glu580Lys was identified in six patients. The patients exhibited corneal dystrophy (5/6), loose skin (5/6) and/or heart arrhythmia (3/6) and one presented with bilateral optic neuropathy. The impact of the mutation on the protein structure was evaluated in silico. The substitution is located in the fifth domain of gelsolin protein, homologous to the second domain harboring the most common pathogenic variant p.Asp214Asn. Structural investigation revealed that the mutation might affect protein folding. Histopathological analysis showed amyloid deposits in the skin. The p.Glu580Lys is associated with corneal dystrophy, strengthening the association of the fifth domain of gelsolin protein with the typical amyloidosis phenotype. Furthermore, optic neuropathy may be related to the disease and is essential to identify before discussing corneal transplantation.

P871Coronary artery aneurysms: clinical features, management and long-term outcomes, insights from the international coronary artery aneurysm registry (CAAR)

Background

Coronary Aneurysms are a focal dilatation of an artery segment of >1.5-fold the normal size of adjacent segments. Some limited series suggested an incidence of 0.3–12%. However, coronary aneurysms are not mentioned in practice guidelines and several questions remain unanswered.

Purpose

To investigate its clinical profile, prognostic predictors, and long term outcomes.

Methods

The coronary artery aneurysm registry (CAAR, NCT02563626) is a collaborative effort involving 32 hospitals across 9 countries (Canada, Cuba, Czech Republic, Germany, Italy, Netherlands, Spain, USA and Uruguay). When eligibility was uncertain, cases were reviewed by a core lab.

Results

We reviewed 436,467 consecutive angiographies between 2004–2016. 1,565 patients were ambispectively included. Global incidence was 0.35%. Most were male (78.5%) with a mean age of 65 years. Cardiovascular risk factors were frequent. An aortopathy history was present in 8.7% but a Kawasaki antecedent was unfrequent (0.3%).

The main indication for cath was an ACS in 966 cases. Most aneurysms were saccular and 82 giant. The number of aneurisms was low, mainly with 1–2 (95.8%) and only 3 patients with ≥6, proportionally with more coronary stenosis. The most affected artery was the LAD. Aortopathy was related with higher number of aneurysms. Most received any revascularization, commonly percutaneous (PCI). During a follow-up of 37.2 months, 485 suffered a MACE, (death/heart failure/unstable angina/reinfarction) and 240 died. Age, race, diabetes, renal failure, peripheral disease, acute cath, coronary stenosis, LVEF and anticoagulation remained as predictors of death/MACE after multivariate adjustments, without no major differences comparing CABG vs PCI. No restenosis was found in aneurysm with DES but those with BMS suffered 4 (p=0.002). MACE and death were more frequent in patients who received BMS.

Figure 1

Conclusions

Coronary aneurysmal disease is not uncommon. It is associated with severe coronary stenosis and a high cardiovascular risk burden, pointing out an aggressive atherosclerotic status. Antiplatelet therapy is a reasonable option and interventional procedures safe and effective, compared with surgery. Drug eluting stents should be preferred as the default strategy.

Acknowledgement/Funding

None

High-resolution crystal structure of gelsolin domain 2 in complex with the physiological calcium ion

The second domain of gelsolin (G2) hosts mutations responsible for a hereditary form of amyloidosis. The active form of gelsolin is Ca²⁺-bound; it is also a dynamic protein, hence structural biologists often rely on the study of the isolated G2. However, the wild type G2 structure that have been used so far in comparative studies is bound to a crystallographic Cd²⁺, in lieu of the physiological calcium. Here, we report the wild type structure of G2 in complex with Ca²⁺ highlighting subtle ion-dependent differences. Previous findings on different G2 mutations are also briefly revised in light of these results.

Patient selection and percutaneous technique of unprotected left main revascularization

Increasing evidence suggests that percutaneous coronary intervention with newer generation drug-eluting stents may be an acceptable alternative, or even preferred in selected cases to the surgical approach, in patients with left main disease. This review will discuss the anatomic factors, the clinical variables, and the procedural strategies to consider, including physiology assessment and imaging guidance, in order to optimize outcomes.

Cardiac magnetic resonance for ischaemia and viability detection. Guiding patient selection to revascularization in coronary chronic total occlusions: The CARISMA_CTO study design

BACKGROUND

It is debated whether percutaneous revascularization (PCI) of total coronary chronic occlusion (CTO) is superior to optimal medical therapy (OMT) in improving symptoms, left ventricular (LV) function and major adverse cardiac/cerebrovascular events (MACCE). Furthermore, CTO-PCI is a challenging technique, with lower success rate than in other settings. A systematic analysis of baseline LV function, infarction extent and ischaemic burden to predict response to revascularization has never been performed.

PURPOSES

To establish a CMR protocol to identify patients (pts) who can benefit most from CTO-PCI. Myocardial viability/ischaemia retains high biological plausibility as predictors of response to revascularization. Therefore, baseline viability (necrotic tissue extent, response to inotropic stimulation) and ischaemia (perfusion defect, wall motion abnormality during stress) will be studied as potential predictors of mechanical LV segmental improvement and ischaemic burden reduction in CTO territory (primary endpoint), LV remodelling and global function, Seattle Angina Questionnaire, and MACCE improvement (secondary endpoints) in the follow-up.

METHODS

Pts with CTO suitable for PCI undergo stress-CMR for viability/ischaemia assessment. Pts with normal LV function undergo adenosine, those with moderately-reduced ejection fraction (EF) and wall motion abnormalities high-dose dobutamine, pts with EF <35% low-dose dobutamine. All pts undergo late gadolinium enhancement and repeat the same scan at 12 ± 3 months, regardless of PCI success or decision for OMT.

CONCLUSIONS

A multi-parameter CMR protocol tailored on pts characteristics to study viability/ischaemia could help in identifying responders in terms of LV function, ischaemic burden and clinical outcome among pts suitable for CTO-PCI, improving selection of best candidates to percutaneous revascularization.

Identification of a Small Molecule That Compromises the Structural Integrity of Viroplasms and Rotavirus Double-Layered Particles

Despite the availability of two attenuated vaccines, rotavirus (RV) gastroenteritis remains an important cause of mortality among children in developing countries, causing about 215,000 infant deaths annually. Currently, there are no specific antiviral therapies available. RV is a nonenveloped virus with a segmented double-stranded RNA genome. Viral genome replication and assembly of transcriptionally active double-layered particles (DLPs) take place in cytoplasmic viral structures called viroplasms. In this study, we describe strong impairment of the early stages of RV replication induced by a small molecule known as an RNA polymerase III inhibitor, ML-60218 (ML). This compound was found to disrupt already assembled viroplasms and to hamper the formation of new ones without the need for de novo transcription of cellular RNAs. This phenotype was correlated with a reduction in accumulated viral proteins and newly made viral genome segments, disappearance of the hyperphosphorylated isoforms of the viroplasm-resident protein NSP5, and inhibition of infectious progeny virus production. In in vitro transcription assays with purified DLPs, ML showed dose-dependent inhibitory activity, indicating the viral nature of its target. ML was found to interfere with the formation of higher-order structures of VP6, the protein forming the DLP outer layer, without compromising its ability to trimerize. Electron microscopy of ML-treated DLPs showed dose-dependent structural damage. Our data suggest that interactions between VP6 trimers are essential, not only for DLP stability, but also for the structural integrity of viroplasms in infected cells.IMPORTANCE Rotavirus gastroenteritis is responsible for a large number of infant deaths in developing countries. Unfortunately, in the countries where effective vaccines are urgently needed, the efficacy of the available vaccines is particularly low. Therefore, the development of antivirals is an important goal, as they might complement the available vaccines or represent an alternative option. Moreover, they may be decisive in fighting the acute phase of infection. This work describes the inhibitory effect on rotavirus replication of a small molecule initially reported as an RNA polymerase III inhibitor. The molecule is the first chemical compound identified that is able to disrupt viroplasms, the viral replication machinery, and to compromise the stability of DLPs by targeting the viral protein VP6. This molecule thus represents a starting point in the development of more potent and less cytotoxic compounds against rotavirus infection.

Crystal structure of LptH, the periplasmic component of the lipopolysaccharide transport machinery from Pseudomonas aeruginosa

Lipopolysaccharide (LPS) is the main glycolipid present in the outer leaflet of the outer membrane (OM) of Gram-negative bacteria, where it modulates OM permeability, therefore preventing many toxic compounds from entering the cell. LPS biogenesis is an essential process in Gram-negative bacteria and thus is an ideal target pathway for the development of novel specific antimicrobials. The lipopolysaccharide transport (Lpt) system is responsible for transporting LPS from the periplasmic surface of the inner membrane, where it is assembled, to the cell surface where it is then inserted in the OM. The Lpt system has been widely studied in Escherichia coli, where it consists of seven essential proteins located in the inner membrane (LptBCFG), in the periplasm (LptA) and in the OM (LptDE). In the present study, we focus our attention on the Pseudomonas aeruginosa PAO1 Lpt system. We identified an LptA orthologue, named LptH, and solved its crystal structure at a resolution of 2.75 Å. Using interspecies complementation and site-directed mutagenesis of a conserved glycine residue, we demonstrate that P. aeruginosa LptH is the genetic and functional homologue of E. coli LptA, with whom it shares the β-jellyroll fold identified also in other members of the canonical E. coli Lpt model system. Furthermore, we modeled the N-terminal β-jellyroll domain of P. aeruginosa LptD, based on the crystal structure of its homologue from Shigella flexneri, aiming to provide more general insight into the mechanism of LPS binding and transport in P. aeruginosa. Both LptH and LptD may represent new targets for the discovery of next generation antibacterial drugs, targeting specific opportunistic pathogens such as P. aeruginosa.

DATABASE

Coordinates and structure factors have been deposited in the Protein Data Bank under accession number PDB 4uu4.

Appraising failure of surgical and percutaneous revascularization: long term outcomes from an observational registry

AIM

Many randomized trials have compared coronary artery bypass graft (CABG) and percutaneous coronary intervention (PCI) in terms of efficacy, but data comparing outcomes of patients in which these two techniques have failed are lacking.

METHODS

We included patients undergoing PCI at our center between July 2002 and December 2004. Subjects were distinguished in 2 groups: those with at least one occluded or stenotic saphenous vein graft (CABG failure), and those with at least one stent with angiographically documented restenosis (PCI failure). The primary endpoint was the long-term rate of major adverse clinical events.

RESULTS

Two hundred and thirthy four patients were included, with a medium follow up of 61±13 months; 134 were assigned to the CABG failure group, and 104 to the PCI failure group, sharing high rates of baseline risk factors. At long term rates of death were higher in post CABG group (22.1% vs. 9.9%; P=0.015, RR 2.24 C.I. 95% 1.14-4.40) while death rates in patients with diagnosis of diabetes mellitus (24.0% vs. 23.5%; P=0.969, RR 1.020 C.I. 95% 0.38-2.74) were not different

CONCLUSION

PCI can be safely offered to both these kinds of patients: as recently demonstrated post CABG outcomes seem to be more favorable in patients with diabetes mellitus.

Incidence and very long- term outcomes of stent thrombosis after bare-metal or drug-eluting stent implantation: a retrospective analysis

AIM

Stent thrombosis is a major safety issue after percutaneous coronary intervention (PCI) with stent implantation and it is associated with major early and mid-term complications. However, its long-term impact has been incompletely described. We thus aimed to appraise incidence, predictors and very long-term outlook of stent thrombosis after bare metal stent (BMS) or drug-eluting stent (DES) implantation.

METHODS

We identified all patients undergoing PCI with BMS or DES at our center between July 2002 and June 2004. For the purpose of this study, we employed a composite definition of stent thrombosis including any Academic Research Consortium stent thromboses (definite, probable, or possible). We adjudicated the following clinical events: death, myocardial infarction (stent thrombosis related), repeated revascularization, and the composite of these events (i.e., major adverse cardiac events, MACE).

RESULTS

A total of 1112 patients were included, 854 (76.8%) treated with BMS and 258 (23.2%) treated with DES. At a median follow-up of 61.2 (11.03) months the incidence of stent thrombosis was 20 (1.8%), with 14 (1.3%) definite, 4 (0.4%) probable, and 2 (0.1%) possible according to the American Research Consortium statement. Patients developing stent thrombosis were more likely to have more complex angiographic features at baseline (including angiographically evident thrombus, 4 [20%] vs. 73 [6.6%], P=0.02) and a saphenous vein graft as target vessel (2 [10%] vs. 28 [2.5%], P=0.04). Conversely, being treated with a BMS or a DES did not confer any significant decrease or increase in the risk of stent thrombosis, as 7 [35%] of those with stent thrombosis had received at least a DES vs. 251 [22.9%] of those without stent thrombosis, P=0.28). Early clinical outcomes (at 30 days) distinguishing those with stent thrombosis versus those without were as follows: death in four (20%) vs. 2 (0.2%, P<0.001), myocardial infarction in 1 (5%) vs. 7 (0.6%, P=0.02), revascularization in 5 (25%) vs. 43 (3.9%, P<0.001), and MACE in 8 (40%) vs. 53 (4.8%, P<0.001). After more than 60 months of clinical follow-up, outcomes were as follows: death in 7 (35%) vs. 147 (13.5%, P=0.057), myocardial infarction in 6 (30%) vs. 40 (3.6%, P<0.001), revascularization in 15 (75%) vs. 317 (29%, P<0.001), and MACE in 19 (95%) vs. 453 (41.5%, P<0.001).

CONCLUSION

This long-term registry shows that stent thrombosis remains a major safety issue after PCI with stent implantation, with a significant prognostic impact. However, in the present work the risk of stent thrombosis was similar with either DES or BMS, suggesting thus that DES are not associated with any increase in long-term thrombotic risk in comparison to BMS.

Short and long term outcome of percutaneous coronary intervention with drug eluting stent and bare metal stent in patients with chronic kidney disease

AIM

Coronary artery disease represents the most important cause of mortality and morbidity in chronic kidney disease (CKD). Despite continuous improvements in percutaneous coronary intervention (PCI), CKD is still associated with more adverse events after PCI. We performed a retrospective study to compare bare metal stents (BMS) versus drug eluting stents (DES) in CKD.

METHODS

We included consecutively all patients undergoing PCI at our Centre from July 2002 to December 2005 with CKD, defined as creatinine clearance <60 mL/min. Patients who received only DES were compared to those who received only BMS. The primary end-point was the long-term rate of major adverse cardiac events (MACE, i.e. the composite of death, myocardial infarction and repeat revascularization).

RESULTS

We included a total of 219 patients with CKD out of a total of 2354 patients, with 164 receiving BMS and 55 DES. After a mean follow up of 48 months, the MACE rate was significantly higher in BMS group (71% versus 38%, P<0.001). A similarly increased risk with BMS was found for death (45% versus 17%, P<0.001), whereas the rates for repeat coronary revascularization, myocardial infarction and stent thrombosis were not significantly different. Multivariable analysis showed that BMS vs.. DES implantation was not statistically significant associated with MACE, death, myocardial infarction, rePTCA or stent thrombosis.

CONCLUSION

Compared with BMS, use of DES in patients with CKD is safe and effective in reducing adverse outcomes. However, differences found between groups in clinical end-point could be ascribed to selection bias and confounding factors.

Very long-term outcome of peripheral arterial disease in patients undergoing percutaneous coronary revascularization: a retrospective analysis

AIM

Peripheral arterial disease (PAD) in patients undergoing percutaneous coronary intervention (PCI) with stent implantation is a well known risk factor leading to an increased rates of stroke, cardiovascular death and myocardial infarction. Anyway there are few data on very-long term outcome (more than 1 year follow up) of PAD after stent implantation. We thus aimed to evaluate the influence of PAD on very long-term outcome of our PCI-population.

METHODS

We retrospectively identified all patients undergoing PCI with stent implantation at our center between July 2002 and June 2004, and thus eligible for at least 4 years of follow-up. For the purpose of this study, we considered a diagnosis of PAD based on clinical evaluation and/or angiographic documentation. We adjudicated the following clinical events: death, myocardial infarction, repeat revascularization, and their composite (i.e. major adverse cardiac events, MACE). RESULTS; A total of 1008 patients were included, 109 with PAD and 899 Without PAD. Those with had more often diabetes (35% vs. 25%, P=0.002), hypertension (83% vs. 68%, P=0.001) and unfavorable basal clinical condition at the start of this study: past-Percutaneous Coronary Intervention (PCI) (30% vs. 22%, P=0.005), past-Coronary Artery Bypass Graft (CABG) (24% vs. 14%, P=0.001), ejection fraction (EF) <35% (14% vs. 7%, P=0.02) and chronic renal failure (CRF) (15% vs. 6%, P=0.002). In addiction patient with PAD were more likely to have chronic total occlusion (CTO) (36% vs. 25%, p=0.02) and unprotected left main (16% vs. 8%,P=0.01). Clinical outcome at the time of follow-up (4,42 ± 1,66 years) was as follow: Revascularization (53% vs. 37%, P=0.002), Cardiac death (21% vs. 13%, P=0.04), MACE (69% vs. 49%, p<.001). Independent predictors of MACE according to our survival analysis were: PAD (HR 1.31; 95% CI 1.01-1.69), Age >75 (HR 1.23; 95% CI 1-1.51), Chronic heart failure (HR1.72; 95% CI 1.19-2.5), Unprotected left main (HR 1.48; 95% CI 1.12-1.96).

CONCLUSION

This long-term registry shows that PAD remains an important clinical condition that negatively influences the outcome of patients undergoing PCI with stent implantation in a very long-term follow-up period.

Quantitative expression of the mutated lamin A/C gene in patients with cardiolaminopathy

OBJECTIVES

The authors sought to investigate the gene and protein expression in Lamin A/C (LMNA)-mutated dilated cardiolaminopathy (DCM) patients (DCM(LMNAMut)) versus LMNA-wild-type DCM (DCM(LMNAWT)), and normal controls (CTRL(LMNAWT)).

BACKGROUND

Dilated cardiolaminopathies are clinically characterized by high arrhythmogenic risk and caused by LMNA mutations. Little is known regarding quantitative gene expression (QGE) of the LMNA gene in blood and myocardium, as well as regarding myocardial expression of the lamin A/C protein.

METHODS

Using the comparative ΔΔCT method, we evaluated the QGE of LMNA (QGE(LMNA)) in peripheral blood and myocardial RNA from carriers of LMNA mutations, versus blood and myocardial samples from DCM(LMNAWT) patients and CTRL(LMNAWT) individuals. After generating reference values in normal controls, QGE(LMNA) was performed in 311 consecutive patients and relatives, blind to genotype, to assess the predictive value of QGE(LMNA) for the identification of mutation carriers. In parallel, Lamin A/C was investigated in myocardial samples from DCM(LMNAMut) versus DCM(LMNAWT) versus normal hearts (CTRL(LMNAWT)).

RESULTS

LMNA was significantly underexpressed in mRNA from peripheral blood and myocardium of DCM(LMNAMut) patients versus DCM(LMNAWT) and CTRL(LMNAWT). In 311 individuals, blind to genotype, the QGE(LMNA) showed 100% sensitivity and 87% specificity as a predictor of LMNA mutations. The receiver-operating characteristic curve analysis yielded an area under the curve of 0.957 (p < 0.001). Loss of protein in cardiomyocytes' nuclei was documented in DCM(LMNAMut) patients.

CONCLUSIONS

The reduced expression of LMNA gene in blood is a novel potential predictive biomarker for dilated cardiolaminopathies with parallel loss of protein expression in cardiomyocyte nuclei.

Percutaneous drug-eluting stent implantation in diabetic patients: short and long term outcomes from an observational study

AIM

The introduction of drug-eluting stents (DES) has markedly improved mid-term results of percutaneous coronary intervention (PCI) in diabetics. However, it is unclear whether the risk-benefit balance of DES in diabetics is maintained also at long-term and in insulin-requiring patients. We thus aimed to appraise long-term outcomes of diabetic patients treated with PCI with DES, stratifying according to insulin therapy.

METHODS

We retrospectively collected baseline, procedural and outcome data from all patients undergoing PCI with DES from July 2002 to June 2004 at our center. We distinguished three groups: insulin-requiring diabetics, non-insulin-requiring diabetics and patients without diabetes. The primary end-point was the long-term rate of major adverse cardiac events (MACE, i.e. the composite of death, myocardial infarction, or target vessel revascularization). We also considered stent thrombosis according to the Academic Research Consortium Definition.

RESULTS

We included a total of 1266 patients, with 3% of insulin-requiring diabetes, 22% with non-insulin-requiring diabetes, and 75% without diabetes. There were significant differences across groups in prevalence of male gender (respectively, 32.4%, 74.6% and 81%, P<0.001), and DES usage (54.1%, 34%, and 30.4%, P=0.007). Thirty-day MACE occurred with similar frequency in the three groups (8.1%, 7.3% and 6.3%, P=0.78), with death in 3%, 2%, and 1.4% (P=0.71) and myocardial infarction in 5.4%, 1.8% and 0.8% (P=0.02). After a median follow-up period of 58 months, MACE occurred in 59.5% of patients with insulin-requiring diabetes, in 50.6% of non-insulin-requiring diabetics and in 38.9% of non-diabetics (P<0.001). Death occurred in 24.3%, 17.5% and 8.5%, (P<0.001), myocardial infarction in 10.8%, 6.6%, and 5.1% (P=0.25), repeat revascularization in 46%, 31.6%, and 30% (P=0.11), and definite stent thrombosis in 0%, 1.1%, and 1.3% (P=0.78).

CONCLUSION

Our study confirms the high risk profile of diabetic patients, especially when ischemic disease it is known. In this setting, diabetic and comorbidities fix the price not only in term of need of further revascularization, but mainly in survival decrease. It can be concluded that not only revascularization but also ‑ and especially ‑ comorbidities treatment plays a determinant role reducing follow-up events. Further research on additional pharmacologic treatments or hybrid revascularization strategies may mitigate the burden of morbidity and mortality.

Structure and functionality in flavivirus NS-proteins: perspectives for drug design

Flaviviridae are small enveloped viruses hosting a positive-sense single-stranded RNA genome. Besides yellow fever virus, a landmark case in the history of virology, members of the Flavivirus genus, such as West Nile virus and dengue virus, are increasingly gaining attention due to their re-emergence and incidence in different areas of the world. Additional environmental and demographic considerations suggest that novel or known flaviviruses will continue to emerge in the future. Nevertheless, up to few years ago flaviviruses were considered low interest candidates for drug design. At the start of the European Union VIZIER Project, in 2004, just two crystal structures of protein domains from the flaviviral replication machinery were known. Such pioneering studies, however, indicated the flaviviral replication complex as a promising target for the development of antiviral compounds. Here we review structural and functional aspects emerging from the characterization of two main components (NS3 and NS5 proteins) of the flavivirus replication complex. Most of the reviewed results were achieved within the European Union VIZIER Project, and cover topics that span from viral genomics to structural biology and inhibition mechanisms. The ultimate aim of the reported approaches is to shed light on the design and development of antiviral drug leads.

Short and long-term outcomes of percutaneous revascularization in patients with prior coronary artery bypass graft

AIM

Patients with prior coronary artery bypass grafting (CABG) represent a sizable portion of those undergoing percutaneous coronary intervention (PCI): in many instances, it is unclear whether performing PCI on the bypass graft or in the native coronary vessels can offer the best risk-benefit balance.

METHODS

We included patients with prior CABG undergoing PCI at our center between July 2002 and June 2004 and we distinguished them in three groups. Those in whom PCI was performed on stenotic saphenous vein graft (SVG group), those in whom PCI was performed on native vessels despite the presence of potentially treatable SVG disease (optional native group), and those in whom PCI had to be performed mandatorily in the native vessels because of chronic SVG occlusions or disease in non-bypassed segments (mandatory native group). The primary end-point was long-term rate of major adverse clinical events (MACE, i.e. death, myocardial infarction, or target vessel revascularization).

RESULTS

We identified 109 patients: 28 were in the SVG group, 25 in the optional native group, and 56 in the mandatory native group. Early major adverse cardiac events (MACE) occurred with similar frequency in the three groups (respectively, 9.1%, 0% and 5.7%, P=0.35). After more than three years of follow-up, MACE occurred in 39.3% vs. 28 and 39.4% (P=0.59), death occurred in 27.2 vs. 24.0% vs. 13.5% (P=0.30), and TVR in 27.3% vs. 8.0% vs. 28.8% (P=0.14).

CONCLUSION

In selected patients, PCI of native coronary vessels despite the presence of apparently treatable SVG lesions can be envisioned.

The SARS-unique domain (SUD) of SARS coronavirus contains two macrodomains that bind G-quadruplexes

Since the outbreak of severe acute respiratory syndrome (SARS) in 2003, the three-dimensional structures of several of the replicase/transcriptase components of SARS coronavirus (SARS-CoV), the non-structural proteins (Nsps), have been determined. However, within the large Nsp3 (1922 amino-acid residues), the structure and function of the so-called SARS-unique domain (SUD) have remained elusive. SUD occurs only in SARS-CoV and the highly related viruses found in certain bats, but is absent from all other coronaviruses. Therefore, it has been speculated that it may be involved in the extreme pathogenicity of SARS-CoV, compared to other coronaviruses, most of which cause only mild infections in humans. In order to help elucidate the function of the SUD, we have determined crystal structures of fragment 389-652 ("SUD(core)") of Nsp3, which comprises 264 of the 338 residues of the domain. Both the monoclinic and triclinic crystal forms (2.2 and 2.8 A resolution, respectively) revealed that SUD(core) forms a homodimer. Each monomer consists of two subdomains, SUD-N and SUD-M, with a macrodomain fold similar to the SARS-CoV X-domain. However, in contrast to the latter, SUD fails to bind ADP-ribose, as determined by zone-interference gel electrophoresis. Instead, the entire SUD(core) as well as its individual subdomains interact with oligonucleotides known to form G-quadruplexes. This includes oligodeoxy- as well as oligoribonucleotides. Mutations of selected lysine residues on the surface of the SUD-N subdomain lead to reduction of G-quadruplex binding, whereas mutations in the SUD-M subdomain abolish it. As there is no evidence for Nsp3 entering the nucleus of the host cell, the SARS-CoV genomic RNA or host-cell mRNA containing long G-stretches may be targets of SUD. The SARS-CoV genome is devoid of G-stretches longer than 5-6 nucleotides, but more extended G-stretches are found in the 3'-nontranslated regions of mRNAs coding for certain host-cell proteins involved in apoptosis or signal transduction, and have been shown to bind to SUD in vitro. Therefore, SUD may be involved in controlling the host cell's response to the viral infection. Possible interference with poly(ADP-ribose) polymerase-like domains is also discussed.

Percutaneous aortic valve replacement in two cases at high surgical risk: procedural details and implications for patient selection

The morbidity and mortality burden of heart valve disease is increasing in the developing world, especially among the elderly. Whereas surgery remains the standard of care in fit patients with degenerative aortic stenosis, percutaneous aortic valve replacement could become an effective alternative to surgery in selected higher risk patients. The authors report on two women with aortic stenosis, both at high surgical risk (an 81-year-old female with coronary artery and cerebro-vascular disease, and a 70-year-old female with end-stage cirrhosis), in whom percutaneous valve replacement was effectively performed by means of transfemoral access and retrograde CoreValve Re-valving System implantation. Two major post-procedural complications occurred, both effectively managed, in the second patient: a third degree atrio-ventricular block (requiring permanent pace-maker implantation) and bleeding from the right femoral artery access (requiring implantation of two covered stents and blood transfusion). Despite the increased baseline risk, both patients were discharged asymptomatic, the first twelve days and the other three weeks after admission. In the authors' experience percutaneous aortic valve replacement can be performed with reasonable safety in patient with severe aortic stenosis at high surgical risk.

Recognition of RNA cap in the Wesselsbron virus NS5 methyltransferase domain: implications for RNA-capping mechanisms in Flavivirus

The mRNA-capping process starts with the conversion of a 5'-triphosphate end into a 5'-diphosphate by an RNA triphosphatase, followed by the addition of a guanosine monophosphate unit in a 5'-5' phosphodiester bond by a guanylyltransferase. Methyltransferases are involved in the third step of the process, transferring a methyl group from S-adenosyl-l-methionine to N7-guanine (cap 0) and to the ribose 2'OH group (cap 1) of the first RNA nucleotide; capping is essential for mRNA stability and proper replication. In the genus Flavivirus, N7-methyltransferase and 2'O-methyltransferase activities have been recently associated with the N-terminal domain of the viral NS5 protein. In order to further characterize the series of enzymatic reactions that support capping, we analyzed the crystal structures of Wesselsbron virus methyltransferase in complex with the S-adenosyl-l-methionine cofactor, S-adenosyl-l-homocysteine (the product of the methylation reaction), Sinefungin (a molecular analogue of the enzyme cofactor), and three different cap analogues (GpppG, (N7Me)GpppG, and (N7Me)GpppA). The structural results, together with those on other flaviviral methyltransferases, show that the capped RNA analogues all bind to an RNA high-affinity binding site. However, lack of specific interactions between the enzyme and the first nucleotide of the RNA chain suggests the requirement of a minimal number of nucleotides following the cap to strengthen protein/RNA interaction. Our data also show that, following incubation with guanosine triphosphate, Wesselsbron virus methyltransferase displays a guanosine monophosphate molecule covalently bound to residue Lys28, hinting at possible implications for the transfer of a guanine group to ppRNA. The structures of the Wesselsbron virus methyltransferase complexes obtained are discussed in the context of a model for N7-methyltransferase and 2'O-methyltransferase activities.

Crystal structure and activity of Kunjin virus NS3 helicase; protease and helicase domain assembly in the full length NS3 protein

Flaviviral NS3 is a multifunctional protein displaying N-terminal protease activity in addition to C-terminal helicase, nucleoside 5'-triphosphatase (NTPase), and 5'-terminal RNA triphosphatase (RTPase) activities. NS3 is held to support the separation of RNA daughter and template strands during viral replication. In addition, NS3 assists the initiation of replication by unwinding the RNA secondary structure in the 3' non-translated region (NTR). We report here the three-dimensional structure (at 3.1 A resolution) of the NS3 helicase domain (residues 186-619; NS3:186-619) from Kunjin virus, an Australian variant of the West Nile virus. As for homologous helicases, NS3:186-619 is composed of three domains, two of which are structurally related and held to host the NTPase and RTPase active sites. The third domain (C-terminal) is involved in RNA binding/recognition. The NS3:186-619 construct occurs as a dimer in solution and in the crystals. We show that NS3:186-619 displays both ATPase and RTPase activities, that it can unwind a double-stranded RNA substrate, being however inactive on a double-stranded DNA substrate. Analysis of different constructs shows that full length NS3 displays increased helicase activity, suggesting that the protease domain plays an assisting role in the RNA unwinding process. The structural interaction between the helicase and protease domain has been assessed using small angle X-ray scattering on full length NS3, disclosing that the protease and helicase domains build a rather elongated molecular assembly differing from that observed in the NS3 protein from hepatitis C virus.

Structural bases for substrate recognition and activity in Meaban virus nucleoside-2'-O-methyltransferase

Viral methyltransferases are involved in the mRNA capping process, resulting in the transfer of a methyl group from S-adenosyl-L-methionine to capped RNA. Two groups of methyltransferases (MTases) are known: (guanine-N7)-methyltransferases (N7MTases), adding a methyl group onto the N7 atom of guanine, and (nucleoside-2'-O-)-methyltransferases (2'OMTases), adding a methyl group to a ribose hydroxyl. We have expressed and purified two constructs of Meaban virus (MV; genus Flavivirus) NS5 protein MTase domain (residues 1-265 and 1-293, respectively). We report here the three-dimensional structure of the shorter MTase construct in complex with the cofactor S-adenosyl-L-methionine, at 2.9 angstroms resolution. Inspection of the refined crystal structure, which highlights structural conservation of specific active site residues, together with sequence analysis and structural comparison with Dengue virus 2'OMTase, suggests that the crystallized enzyme belongs to the 2'OMTase subgroup. Enzymatic assays show that the short MV MTase construct is inactive, but the longer construct expressed can transfer a methyl group to the ribose 2'O atom of a short GpppAC(5) substrate. West Nile virus MTase domain has been recently shown to display both N7 and 2'O MTase activity on a capped RNA substrate comprising the 5'-terminal 190 nt of the West Nile virus genome. The lack of N7 MTase activity here reported for MV MTase may be related either to the small size of the capped RNA substrate, to its sequence, or to different structural properties of the C-terminal regions of West Nile virus and MV MTase-domains.

Preliminary characterization of (nucleoside-2′-O-)-methyltransferase crystals from Meaban and Yokose flaviviruses. Corrigendum

A corrigendum to the paper by Mastrangelo et al. (2006), Acta Cryst. F62, 768–770.

A correction is made to the names of two of the authors in Mastrangelo et al. (2006), Acta Cryst. F62, 768–770.

Preliminary crystallographic characterization of an RNA helicase from Kunjin virus

Kunjin virus is a member of the Flavivirus genus and is an Australian variant of West Nile virus. The C-terminal domain of the Kunjin virus NS3 protein displays helicase activity. The protein is thought to separate daughter and template RNA strands, assisting the initiation of replication by unwinding RNA secondary structure in the 3' nontranslated region. Expression, purification and preliminary crystallographic characterization of the NS3 helicase domain are reported. It is shown that Kunjin virus helicase may adopt a dimeric assembly in absence of nucleic acids, oligomerization being a means to provide the helicases with multiple nucleic acid-binding capability, facilitating translocation along the RNA strands. Kunjin virus NS3 helicase domain is an attractive model for studying the molecular mechanisms of flavivirus replication, while simultaneously providing a new basis for the rational development of anti-flaviviral compounds.

Preliminary characterization of (nucleoside-2'-O-)-methyltransferase crystals from Meaban and Yokose flaviviruses

Viral methyltranferases (MTase) are involved in the third step of the mRNA-capping process, transferring a methyl group from S-adenosyl-L-methionine (SAM) to the capped mRNA. MTases are classified into two groups: (guanine-N7)-methyltransferases (N7MTases), which add a methyl group onto the N7 atom of guanine, and (nucleoside-2'-O-)-methyltransferases (2'OMTases), which add a methyl group to a ribose hydroxyl. The MTases of two flaviviruses, Meaban and Yokose viruses, have been overexpressed, purified and crystallized in complex with SAM. Characterization of the crystals together with details of preliminary X-ray diffraction data collection (at 2.8 and 2.7 angstroms resolution, respectively) are reported here. The sequence homology relative to Dengue virus 2'OMTase and the structural conservation of specific residues in the putative active sites suggest that both enzymes belong to the 2'OMTase subgroup.