Validation of four-dimensional flow cardiovascular magnetic resonance for aortic stenosis assessment

The management of patients with aortic stenosis (AS) crucially depends on accurate diagnosis. The main aim of this study were to validate the four-dimensional flow (4D flow) cardiovascular magnetic resonance (CMR) methods for AS assessment. Eighteen patients with clinically severe AS were recruited. All patients had pre-valve intervention 6MWT, echocardiography and CMR with 4D flow. Of these, ten patients had a surgical valve replacement, and eight patients had successful transcatheter aortic valve implantation (TAVI). TAVI patients had invasive pressure gradient assessments. A repeat assessment was performed at 3–4 months to assess the remodelling response. The peak pressure gradient by 4D flow was comparable to an invasive pressure gradient (54 ± 26 mmHG vs 50 ± 34 mmHg, P = 0.67). However, Doppler yielded significantly higher pressure gradient compared to invasive assessment (61 ± 32 mmHG vs 50 ± 34 mmHg, P = 0.0002). 6MWT was associated with 4D flow CMR derived pressure gradient (r = −0.45, P = 0.01) and EOA (r = 0.54, P < 0.01) but only with Doppler EOA (r = 0.45, P = 0.01). Left ventricular mass regression was better associated with 4D flow derived pressure gradient change (r = 0.64, P = 0.04). 4D flow CMR offers an alternative method for non-invasive assessment of AS. In addition, 4D flow derived valve metrics have a superior association to prognostically relevant 6MWT and LV mass regression than echocardiography

Mitral regurgitation quantification by cardiac magnetic resonance imaging (MRI) remains reproducible between software solutions

Background: The reproducibility of mitral regurgitation (MR) quantification by cardiovascular magnetic resonance (CMR) imaging using different software solutions remains unclear. This research aimed to investigate the reproducibility of MR quantification between two software solutions: MASS (version 2019 EXP, LUMC, Netherlands) and CAAS (version 5.2, Pie Medical Imaging). Methods: CMR data of 35 patients with MR (12 primary MR, 13 mitral valve repair/replacement, and ten secondary MR) was used. Four methods of MR volume quantification were studied, including two 4D-flow CMR methods (MRMVAV and MRJet) and two non-4D-flow techniques (MRStandard and MRLVRV). We conducted within-software and inter-software correlation and agreement analyses. Results: All methods demonstrated significant correlation between the two software solutions: MRStandard (r=0.92, p<0.001), MRLVRV (r=0.95, p<0.001), MRJet (r=0.86, p<0.001), and MRMVAV (r=0.91, p<0.001). Between CAAS and MASS, MRJet and MRMVAV, compared to each of the four methods, were the only methods not to be associated with significant bias. Conclusions: We conclude that 4D-flow CMR methods demonstrate equivalent reproducibility to non-4D-flow methods but greater levels of agreement between software solutions

Mitral regurgitation quantification by cardiac magnetic resonance imaging (MRI) remains reproducible between software solutions [version 2; peer review: 1 approved]

BACKGROUND: The reproducibility of mitral regurgitation (MR) quantification by cardiovascular magnetic resonance (CMR) imaging using different software solutions remains unclear. This research aimed to investigate the reproducibility of MR quantification between two software solutions: MASS (version 2019 EXP, LUMC, Netherlands) and CAAS (version 5.2, Pie Medical Imaging). METHODS: CMR data of 35 patients with MR (12 primary MR, 13 mitral valve repair/replacement, and ten secondary MR) was used. Four methods of MR volume quantification were studied, including two 4D-flow CMR methods (MRMVAV and MRJet) and two non-4D-flow techniques (MRStandard and MRLVRV). We conducted within-software and inter-software correlation and agreement analyses. RESULTS: All methods demonstrated significant correlation between the two software solutions: MR_{Standard} (r=0.92, p<0.001), MR_{LVRV} (r=0.95, p<0.001), MR_{Jet} (r=0.86, p<0.001), and MR_{MVAV} (r=0.91, p<0.001). Between CAAS and MASS, MR_{Jet} and MR_{MVAV}, compared to each of the four methods, were the only methods not to be associated with significant bias. CONCLUSIONS: We conclude that 4D-flow CMR methods demonstrate equivalent reproducibility to non-4D-flow methods but greater levels of agreement between software solutions

Profiling the Essential Nature of Lipid Metabolism in Asexual Blood and Gametocyte Stages of Plasmodium falciparum

SummaryDuring its life cycle, Plasmodium falciparum undergoes rapid proliferation fueled by de novo synthesis and acquisition of host cell lipids. Consistent with this essential role, Plasmodium lipid synthesis enzymes are emerging as potential drug targets. To explore their broader potential for therapeutic interventions, we assayed the global lipid landscape during P. falciparum sexual and asexual blood stage (ABS) development. Using liquid chromatography-mass spectrometry, we analyzed 304 lipids constituting 24 classes in ABS parasites, infected red blood cell (RBC)-derived microvesicles, gametocytes, and uninfected RBCs. Ten lipid classes were previously uncharacterized in P. falciparum, and 70%–75% of the lipid classes exhibited changes in abundance during ABS and gametocyte development. Utilizing compounds that target lipid metabolism, we affirmed the essentiality of major classes, including triacylglycerols. These studies highlight the interplay between host and parasite lipid metabolism and provide a comprehensive analysis of P. falciparum lipids with candidate pathways for drug discovery efforts

A whole cell pathway screen reveals seven novel chemosensitizers to combat chloroquine resistant malaria

Due to the widespread prevalence of resistant parasites, chloroquine (CQ) was removed from front-line antimalarial chemotherapy in the 1990s despite its initial promise of disease eradication. Since then, resistance-conferring mutations have been identified in transporters such as the PfCRT, that allow for the efflux of CQ from its primary site of action, the parasite digestive vacuole. Chemosensitizing/ chemoreversing compounds interfere with the function of these transporters thereby sensitizing parasites to CQ once again. However, compounds identified thus far have disappointing in vivo efficacy and screening for alternative candidates is required to revive this strategy. In this study, we propose a simple and direct means to rapidly screen for such compounds using a fluorescent-tagged CQ molecule. When this screen was applied to a small library, seven novel chemosensitizers (octoclothepin, methiothepin, metergoline, loperamide, chlorprothixene, L-703,606 and mibefradil) were quickly elucidated, including two which showed greater potency than the classical chemosensitizers verapamil and desipramine

Inhibition of resistance-refractory P. falciparum kinase PKG delivers prophylactic, blood stage, and transmission-blocking antiplasmodial activity

The search for antimalarial chemotypes with modes of action unrelated to existing drugs has intensified with the recent failure of first-line therapies across Southeast Asia. Here, we show that the trisubstituted imidazole MMV030084 potently inhibits hepatocyte invasion by Plasmodium sporozoites, merozoite egress from asexual blood stage schizonts, and male gamete exflagellation. Metabolomic, phosphoproteomic, and chemoproteomic studies, validated with conditional knockdown parasites, molecular docking, and recombinant kinase assays, identified cGMP-dependent protein kinase (PKG) as the primary target of MMV030084. PKG is known to play essential roles in Plasmodium invasion of and egress from host cells, matching MMV030084's activity profile. Resistance selections and gene editing identified tyrosine kinase-like protein 3 as a low-level resistance mediator for PKG inhibitors, while PKG itself never mutated under pressure. These studies highlight PKG as a resistance-refractory antimalarial target throughout the Plasmodium life cycle and promote MMV030084 as a promising Plasmodium PKG-targeting chemotype

In vitro anti-malarial interaction and gametocytocidal activity of cryptolepine

YesBackground: Discovery of novel gametocytocidal molecules is a major pharmacological strategy in the elimination and eradication of malaria. The high patronage of the aqueous root extract of the popular West African anti-malarial plant Cryptolepis sanguinolenta (Periplocaceae) in traditional and hospital settings in Ghana has directed this study investigating the gametocytocidal activity of the plant and its major alkaloid, cryptolepine. This study also investigates the anti-malarial interaction of cryptolepine with standard anti-malarials, as the search for new anti-malarial combinations continues. Methods: The resazurin-based assay was employed in evaluating the gametocytocidal properties of C. sanguinolenta and cryptolepine against the late stage (IV/V) gametocytes of Plasmodium falciparum (NF54). A fixed ratio method based on the SYBR Green I fluorescence-based assay was used to build isobolograms from a combination of cryptolepine with four standard anti-malarial drugs in vitro using the chloroquine sensitive strain 3D7. Results: Cryptolepis sanguinolenta ( IC50 = 49.65 nM) and its major alkaloid, cryptolepine ( IC50 = 1965 nM), showed high inhibitory activity against the late stage gametocytes of P. falciparum (NF54). In the interaction assays in asexual stage, cryptolepine showed an additive effect with both lumefantrine and chloroquine with mean ΣFIC50s of 1.017 ± 0.06 and 1.465 ± 0.17, respectively. Cryptolepine combination with amodiaquine at therapeutically relevant concentration ratios showed a synergistic effect (mean ΣFIC50 = 0.287 ± 0.10) whereas an antagonistic activity (mean ΣFIC50 = 4.182 ± 0.99) was seen with mefloquine. Conclusions: The findings of this study shed light on the high gametocytocidal properties of C. sanguinolenta and cryptolepine attributing their potent anti-malarial activity mainly to their effect on both the sexual and asexual stages of the parasite. Amodiaquine is a potential drug partner for cryptolepine in the development of novel fixed dose combinations

Absence of association between pyronaridine in vitro responses and polymorphisms in genes involved in quinoline resistance in Plasmodium falciparum

<p>Abstract</p> <p>Background</p> <p>The aim of the present work was to assess the <it>in vitro </it>cross-resistance of pyronaridine with other quinoline drugs, artesunate and several other commonly used anti-malarials and to evaluate whether decreased susceptibility to pyronaridine could be associated with genetic polymorphisms in genes involved in reduced quinoline susceptibility, such as <it>pfcrt</it>, <it>pfmdr1</it>, <it>pfmrp </it>and <it>pfnhe</it>.</p> <p>Methods</p> <p>The <it>in vitro </it>chemosusceptibility profiles of 23 strains of <it>Plasmodium falciparum </it>were analysed by the standard 42-hour ³H-hypoxanthine uptake inhibition method for pyronaridine, artesunate, chloroquine, monodesethylamodiaquine, quinine, mefloquine, lumefantrine, atovaquone, pyrimethamine and doxycycline. Genotypes were assessed for <it>pfcrt</it>, <it>pfmdr1</it>, <it>pfnhe-1 </it>and <it>pfmrp </it>genes.</p> <p>Results</p> <p>The IC₅₀values for pyronaridine ranged from 15 to 49 nM (geometric mean = 23.1 nM). A significant positive correlation was found between responses to pyronaridine and responses to artesunate (<it>r²</it>= 0.20; <it>P </it>= 0.0317) but too low to suggest cross-resistance. No significant correlation was found between pyronaridine IC₅₀and responses to other anti-malarials. Significant associations were not found between pyronaridine IC₅₀and polymorphisms in <it>pfcrt</it>, <it>pfmdr1</it>, <it>pfmrp </it>or <it>pfnhe-1</it>.</p> <p>Conclusion</p> <p>There was an absence of cross-resistance between pyronaridine and quinolines, and the IC₅₀values for pyronaridine were found to be unrelated to mutations in the transport protein genes <it>pfcrt</it>, <it>pfmdr1</it>, <it>pfmrp </it>or <it>pfnhe-1</it>, known to be involved in quinoline resistance. These results confirm the interest and the efficacy of the use of a combination of pyronaridine and artesunate in areas in which parasites are resistant to quinolines.</p

Rapid Identification of Malaria Vaccine Candidates Based on α-Helical Coiled Coil Protein Motif

To identify malaria antigens for vaccine development, we selected α-helical coiled coil domains of proteins predicted to be present in the parasite erythrocytic stage. The corresponding synthetic peptides are expected to mimic structurally “native” epitopes. Indeed the 95 chemically synthesized peptides were all specifically recognized by human immune sera, though at various prevalence. Peptide specific antibodies were obtained both by affinity-purification from malaria immune sera and by immunization of mice. These antibodies did not show significant cross reactions, i.e., they were specific for the original peptide, reacted with native parasite proteins in infected erythrocytes and several were active in inhibiting in vitro parasite growth. Circular dichroism studies indicated that the selected peptides assumed partial or high α-helical content. Thus, we demonstrate that the bioinformatics/chemical synthesis approach described here can lead to the rapid identification of molecules which target biologically active antibodies, thus identifying suitable vaccine candidates. This strategy can be, in principle, extended to vaccine discovery in a wide range of other pathogens

Potent dual inhibitors of Plasmodium falciparum M1 and M17 aminopeptidases through optimization of S1 pocket interactions

Malaria remains a global health problem, and though international efforts for treatment and eradication have made some headway, the emergence of drug-resistant parasites threatens this progress. Antimalarial therapeutics acting via novel mechanisms are urgently required. P. falciparum M1 and M17 are neutral aminopeptidases which are essential for parasite growth and development. Previous work in our group has identified inhibitors capable of dual inhibition of PfA-M1 and PfA-M17, and revealed further regions within the protease S1 pockets that could be exploited in the development of ligands with improved inhibitory activity. Herein, we report the structure-based design and synthesis of novel hydroxamic acid analogues that are capable of potent inhibition of both PfA-M1 and PfA-M17. Furthermore, the developed compounds potently inhibit Pf growth in culture, including the multi-drug resistant strain Dd2. The ongoing development of dual PfA-M1/PfA-M17 inhibitors continues to be an attractive strategy for the design of novel antimalarial therapeutics