Aortic arch surgery for DeBakey type 1 aortic dissection in patients aged 60 years or younger.

BACKGROUND: Extended aortic repair is considered a key issue for the long-term durability of surgery for DeBakey type 1 aortic dissection. The risk of aortic degeneration may be higher in young patients due to their long life expectancy. The early outcome and durability of aortic surgery in these patients were investigated in the present study. METHODS: The subjects of the present analysis were patients under 60 years old who underwent surgical repair for acute DeBakey type 1 aortic dissection at 18 cardiac surgery centres across Europe between 2005 and 2021. Patients underwent ascending aortic repair or total aortic arch repair using the conventional technique or the frozen elephant trunk technique. The primary outcome was 5-year cumulative incidence of reoperation on the distal aorta. RESULTS: Overall, 915 patients underwent surgical ascending aortic repair and 284 patients underwent surgical total aortic arch repair. The frozen elephant trunk procedure was performed in 128 patients. Among 245 propensity score-matched pairs, total aortic arch repair did not decrease the rate of distal aortic reoperation compared to ascending aortic repair (5-year cumulative incidence, 6.7% versus 6.7%, subdistributional hazard ratio 1.127, 95% c.i. 0.523 to 2.427). Total aortic arch repair increased the incidence of postoperative stroke/global brain ischaemia (25.7% versus 18.4%, P = 0.050) and dialysis (19.6% versus 12.7%, P = 0.003). Five-year mortality was comparable after ascending aortic repair and total aortic arch repair (22.8% versus 27.3%, P = 0.172). CONCLUSIONS: In patients under 60 years old with DeBakey type 1 aortic dissection, total aortic arch replacement compared with ascending aortic repair did not reduce the incidence of distal aortic operations at 5 years. When feasible, ascending aortic repair for DeBakey type 1 aortic dissection is associated with satisfactory early and mid-term outcomes. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04831073.

Identification and Validation of Compounds Targeting Leishmania major Leucyl-Aminopeptidase M17.

Leishmaniasis is a neglected tropical disease; there is currently no vaccine and treatment is reliant upon a handful of drugs suffering from multiple issues including toxicity and resistance. There is a critical need for development of new fit-for-purpose therapeutics, with reduced toxicity and targeting new mechanisms to overcome resistance. One enzyme meriting investigation as a potential drug target in Leishmania is M17 leucyl-aminopeptidase (LAP). Here, we aimed to chemically validate LAP as a drug target in L. major through identification of potent and selective inhibitors. Using RapidFire mass spectrometry, the compounds DDD00057570 and DDD00097924 were identified as selective inhibitors of recombinant Leishmania major LAP activity. Both compounds inhibited in vitro growth of L. major and L. donovani intracellular amastigotes, and overexpression of LmLAP in L. major led to reduced susceptibility to DDD00057570 and DDD00097924, suggesting that these compounds specifically target LmLAP. Thermal proteome profiling revealed that these inhibitors thermally stabilized two M17 LAPs, indicating that these compounds selectively bind to enzymes of this class. Additionally, the selectivity of the inhibitors to act on LmLAP and not against the human ortholog was demonstrated, despite the high sequence similarities LAPs of this family share. Collectively, these data confirm LmLAP as a promising therapeutic target for Leishmania spp. that can be selectively inhibited by drug-like small molecules.

A lineage-specific protein network at the trypanosome nuclear envelope.

The nuclear envelope (NE) separates translation and transcription and is the location of multiple functions, including chromatin organization and nucleocytoplasmic transport. The molecular basis for many of these functions have diverged between eukaryotic lineages. Trypanosoma brucei, a member of the early branching eukaryotic lineage Discoba, highlights many of these, including a distinct lamina and kinetochore composition. Here, we describe a cohort of proteins interacting with both the lamina and NPC, which we term lamina-associated proteins (LAPs). LAPs represent a diverse group of proteins, including two candidate NPC-anchoring pore membrane proteins (POMs) with architecture conserved with S. cerevisiae and H. sapiens, and additional peripheral components of the NPC. While many of the LAPs are Kinetoplastid specific, we also identified broadly conserved proteins, indicating an amalgam of divergence and conservation within the trypanosome NE proteome, highlighting the diversity of nuclear biology across the eukaryotes, increasing our understanding of eukaryotic and NPC evolution.

Femoral arterial cannulation for surgical repair of stanford type A aortic dissection.

BACKGROUND: The benefits and harms associated with femoral artery cannulation over other sites of arterial cannulation for surgical repair of acute Stanford type A aortic dissection (TAAD) are not conclusively established. METHODS: We evaluated the outcomes after surgery for TAAD using femoral artery cannulation, supra-aortic arterial cannulation (i.e., innominate/subclavian/axillary artery cannulation), and direct aortic cannulation. RESULTS: 3751 (96.1%) patients were eligible for this analysis. In-hospital mortality using supra-aortic arterial cannulation was comparable to femoral artery cannulation (17.8% vs. 18.4%; adjusted OR 0.846, 95% CI 0.799-1.202). This finding was confirmed in 1028 propensity score-matched pairs of patients with supra-aortic arterial cannulation or femoral artery cannulation (17.5% vs. 17.0%, p = 0.770). In-hospital mortality after direct aortic cannulation was lower compared to femoral artery cannulation (14.0% vs. 18.4%, adjusted OR 0.703, 95% CI 0.529-0.934). Among 583 propensity score-matched pairs of patients, direct aortic cannulation was associated with lower rates of in-hospital mortality (13.4% vs. 19.6%, p = 0.004) compared to femoral artery cannulation. Switching of the primary site of arterial cannulation was associated with increased rate of in-hospital mortality (36.5% vs. 17.0%; adjusted OR 2.730, 95% CI 1.564-4.765). Ten-year mortality was similar in the study cohorts. CONCLUSIONS: In this study, the outcomes of surgery for TAAD using femoral arterial cannulation were comparable to those using supra-aortic arterial cannulation. However, femoral arterial cannulation was associated with higher in-hospital mortality than direct aortic cannulation. TRIAL REGISTRATION: ClinicalTrials.gov registration code: NCT04831073.

Nature of Neurological Complications and Outcome After Surgery for Type A Aortic Dissection.

Surgery for type A aortic dissection (TAAD) is frequently complicated by neurologic complications. The prognostic impact of neurologic complications of different nature has been investigated in this study. The subjects of this analysis were 3,902 patients who underwent surgery for acute TAAD from the multicenter European Registry of Type A Aortic Dissection (ERTAAD). During the index hospitalization, 722 patients (18.5%) experienced stroke/global brain ischemia. Ischemic stroke was detected in 539 patients (13.8%), hemorrhagic stroke in 76 patients (1.9%) and global brain ischemia in 177 patients (4.5%), with a few patients having had findings of more than 1 of these conditions. In-hospital mortality was increased significantly in patients with postoperative ischemic stroke (25.6%, adjusted odds ratio [OR] 2.422, 95% confidence interval [CI] 1.825 to 3.216), hemorrhagic stroke (48.7%, adjusted OR 4.641, 95% CI 2.524 to 8.533), and global brain ischemia (74.0%, adjusted OR 22.275, 95% CI 14.537 to 35.524) compared with patients without neurologic complications (13.5%). Similarly, patients who experienced ischemic stroke (46.3%, adjusted hazard ratio [HR] 1.719, 95% CI 1.434 to 2.059), hemorrhagic stroke (62.8%, adjusted HR 3.236, 95% CI 2.314 to 4.525), and global brain ischemia (83.9%, adjusted HR 12.777, 95% CI 10.325 to 15.810) had significantly higher 5-year mortality than patients without postoperative neurologic complications (27.5%). The negative prognostic effect of neurologic complications on survival vanished about 1 year after surgery. In conclusion, postoperative ischemic stroke, hemorrhagic stroke, and global cerebral ischemia increased early and midterm mortality after surgery for acute TAAD. The magnitude of risk of mortality increased with the severity of the neurologic complications, with postoperative hemorrhagic stroke and global brain ischemia being highly lethal complications.

Diameter and dissection of the abdominal aorta and the risk of distal aortic reoperation after surgery for type A aortic dissection.

BACKGROUND: Surgery for Stanford type A aortic dissection (TAAD) is associated with an increased risk of late aortic reoperations due to degeneration of the dissected aorta. METHODS: The subjects of this analysis were 990 TAAD patients who survived surgery for acute TAAD and had complete data on the diameter and dissection status of all aortic segments. RESULTS: After a mean follow-up of 4.2 ± 3.6 years, 60 patients underwent 85 distal aortic reoperations. Ten-year cumulative incidence of distal aortic reoperation was 9.6%. Multivariable competing risk analysis showed that the maximum preoperative diameter of the abdominal aorta (SHR 1.041, 95%CI 1.008-1.075), abdominal aorta dissection (SHR 2.133, 95%CI 1.156-3.937) and genetic syndromes (SHR 2.840, 95%CI 1.001-8.060) were independent predictors of distal aortic reoperation. Patients with a maximum diameter of the abdominal aorta >30 mm and/or abdominal aortic dissection had a cumulative incidence of 10-year distal aortic reoperation of 12.0% compared to 5.7% in those without these risk factors (adjusted SHR 2.076, 95%CI 1.062-4.060). CONCLUSION: TAAD patients with genetic syndromes, and increased size and dissection of the abdominal aorta have an increased the risk of distal aortic reoperations. A policy of extensive surgical or hybrid primary aortic repair, completion endovascular procedures for aortic remodeling and tight surveillance may be justified in these patients. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04831073.

Classification of the Urgency of the Procedure and Outcome of Acute Type A Aortic Dissection.

Surgery for type A aortic dissection (TAAD) is associated with a high risk of early mortality. The prognostic impact of a new classification of the urgency of the procedure was evaluated in this multicenter cohort study. Data on consecutive patients who underwent surgery for acute TAAD were retrospectively collected in the multicenter, retrospective European Registry of TAAD (ERTAAD). The rates of in-hospital mortality of 3,902 consecutive patients increased along with the ERTAAD procedure urgency grades: urgent procedure 10.0%, emergency procedure grade 1 13.3%, emergency procedure grade 2 22.1%, salvage procedure grade 1 45.6%, and salvage procedure grade 2 57.1% (p <0.0001). Preoperative arterial lactate correlated with the urgency grades. Inclusion of the ERTAAD procedure urgency classification significantly improved the area under the receiver operating characteristics curves of the regression model and the integrated discrimination indexes and the net reclassification indexes. The risk of postoperative stroke/global brain ischemia, mesenteric ischemia, lower limb ischemia, dialysis, and acute heart failure increased along with the urgency grades. In conclusion, the urgency of surgical repair of acute TAAD, which seems to have a significant impact on the risk of in-hospital mortality, may be useful to improve the stratification of the operative risk of these critically ill patients. This study showed that salvage surgery for TAAD is justified because half of the patients may survive to discharge.

Identification of a potent and selective LAPTc inhibitor by RapidFire-Mass Spectrometry, with antichagasic activity.

BACKGROUND: Chagas disease is caused by the protozoan parasite Trypanosoma cruzi and leads to ~10,000 deaths each year. Nifurtimox and benznidazole are the only two drugs available but have significant adverse effects and limited efficacy. New chemotherapeutic agents are urgently required. Here we identified inhibitors of the acidic M17 leucyl-aminopeptidase from T. cruzi (LAPTc) that show promise as novel starting points for Chagas disease drug discovery. METHODOLOGY/PRINCIPAL FINDINGS: A RapidFire-MS screen with a protease-focused compound library identified novel LAPTc inhibitors. Twenty-eight hits were progressed to the dose-response studies, from which 12 molecules inhibited LAPTc with IC50 < 34 µM. Of these, compound 4 was the most potent hit and mode of inhibition studies indicate that compound 4 is a competitive LAPTc inhibitor, with Ki 0.27 µM. Compound 4 is selective with respect to human LAP3, showing a selectivity index of >500. Compound 4 exhibited sub-micromolar activity against intracellular T. cruzi amastigotes, and while the selectivity-window against the host cells was narrow, no toxicity was observed for un-infected HepG2 cells. In silico modelling of the LAPTc-compound 4 interaction is consistent with the competitive mode of inhibition. Molecular dynamics simulations reproduce the experimental binding strength (-8.95 kcal/mol), and indicate a binding mode based mainly on hydrophobic interactions with active site residues without metal cation coordination. CONCLUSIONS/SIGNIFICANCE: Our data indicates that these new LAPTc inhibitors should be considered for further development as antiparasitic agents for the treatment of Chagas disease.

Distal Repair After Total Aortic Arch Replacement With Frozen Elephant Trunk in Patients With Chronic Multilevel Thoracic Aortic Disease.

OBJECTIVE: To examine the management of distal aortic disease after total arch replacement with the frozen elephant trunk (TAR + FET) in patients with chronic thoracic aortic disease. METHODS: Two centre retrospective study of consecutive patients treated between January 2010 and December 2019. The primary endpoint was 30 day or in hospital death. The secondary endpoint was midterm survival. Data are presented as median (interquartile range [IQR]). The χ2 or Fisher's exact test was used as appropriate. Estimated survival (standard error) was assessed by calculating the Kaplan-Meier product limit estimator with right censoring of survival data. A p value of < .050 was considered statistically significant. STROBE guidelines were followed. RESULTS: A total of 158 patients (72 men; median age 70 years, IQR 64, 75; median distal aortic diameter 58 mm, IQR 46, 68; 127 aneurysmal disease, 31 chronic dissection) underwent TAR + FET. The peri-operative mortality rate was 10.1% (9/107 elective, 7/51 non-elective). Of 74 (46.8%) patients with a primary distal seal, seven (9.5%) died peri-operatively, the distal seal was maintained during follow up in 51, nine underwent late distal repair (two planned, seven unplanned; one open, eight endovascular; one peri-operative death) with a median interval to unplanned repair of 777 days (IQR 462, 1480), and seven with loss of seal had no intervention. Distal seal failed in 2/28 (7%) patients with a distal seal length > 30 mm and device oversizing > 10%, compared with 12/39 (31%) patients who did not meet these criteria (p = .031). In 84 patients without a primary distal seal, nine (10.7%) died peri-operatively, the distal aorta remained below the size threshold for repair during follow up in 12 patients, 44 had distal repair (median aortic diameter 64 mm, IQR 60, 75; eight open, one hybrid, 35 endovascular repairs; no deaths) at a median of 256 days (IQR 135, 740), and 19 did not have distal repair at the end of the follow up period: six died before planned repair at a median interval of 115 days (IQR 85, 120); eight were considered unfit; one was assessed as fit but declined; and four patients were awaiting assessment. Median follow up was 46 months (IQR 26, 75): no patients were lost to follow up. Estimated ± standard error five year survival was 61.5 ± 4.1%: elective 70.6 ± 4.7%, non-elective 43.2 ± 7.2%. CONCLUSION: TAR + FET achieved primary distal seal in 47% of patients, but late failure occurred in 21%. Distal repair was ultimately indicated in 84% of survivors without a primary distal seal and of these 70% underwent repair, almost 10% died before planned repair, and 13% were considered unfit. Earlier distal endovascular repair and better assessment of patient fitness may improve midterm outcomes.

Ras superfamily GTPases and signal transduction in Euglena gracilis.

Biological complexity is challenging to define, but can be considered through one or more features, including overall genome size, number of genes, morphological features, multicellularity, number of life cycle stages and the ability to adapt to different environments. Euglena gracilis meets several of these criteria, with a large genome of ∼38,000 protein coding genes and a considerable ability to survive under many different conditions, some of which can be described as challenging or harsh. Potential molecular exemplars of complexity tying these aspects together are signalling pathways, including GTPases, kinases and ubiquitylation, which increase the functionality of the gene-encoded proteome manyfold. Each of these examples can modulate both protein activity and gene expression. To address the connection between genome size and complexity I have undertaken a brief, and somewhat qualitative, survey of the small ras-like GTPase superfamily of E. gracilis. Unexpectedly, apart from Rab-GTPases which control intracellular transport and organelle identify, the size of the GTPase cohort is modest, and, for example, has not scaled with gene number when compared to the close relatives, trypanosomatids. I suggest that understanding the functions of this protein family will be vital to uncovering the complexity of E. gracilis biology.

An allele-selective inter-chromosomal protein bridge supports monogenic antigen expression in the African trypanosome.

UPF1-like helicases play roles in telomeric heterochromatin formation and X-chromosome inactivation, and also in monogenic variant surface glycoprotein (VSG) expression via VSG exclusion-factor-2 (VEX2), a UPF1-related protein in the African trypanosome. We show that VEX2 associates with chromatin specifically at the single active VSG expression site on chromosome 6, forming an allele-selective connection, via VEX1, to the trans-splicing locus on chromosome 9, physically bridging two chromosomes and the VSG transcription and splicing compartments. We further show that the VEX-complex is multimeric and self-regulates turnover to tightly control its abundance. Using single cell transcriptomics following VEX2-depletion, we observed simultaneous derepression of many other telomeric VSGs and multi-allelic VSG expression in individual cells. Thus, an allele-selective, inter-chromosomal, and self-limiting VEX1-2 bridge supports monogenic VSG expression and multi-allelic VSG exclusion.

Evolutionary, structural and functional insights in nuclear organisation and nucleocytoplasmic transport in trypanosomes.

One of the remarkable features of eukaryotes is the nucleus, delimited by the nuclear envelope (NE), a complex structure and home to the nuclear lamina and nuclear pore complex (NPC). For decades, these structures were believed to be mainly architectural elements and, in the case of the NPC, simply facilitating nucleocytoplasmic trafficking. More recently, the critical roles of the lamina, NPC and other NE constituents in genome organisation, maintaining chromosomal domains and regulating gene expression have been recognised. Importantly, mutations in genes encoding lamina and NPC components lead to pathogenesis in humans, while pathogenic protozoa disrupt the progression of normal development and expression of pathogenesis-related genes. Here, we review features of the lamina and NPC across eukaryotes and discuss how these elements are structured in trypanosomes, protozoa of high medical and veterinary importance, highlighting lineage-specific and conserved aspects of nuclear organisation.

Preoperative arterial lactate and outcome after surgery for type A aortic dissection: The ERTAAD multicenter study.

Background: Acute type A aortic dissection (TAAD) is associated with significant mortality and morbidity. In this study we evaluated the prognostic significance of preoperative arterial lactate concentration on the outcome after surgery for TAAD. Methods: The ERTAAD registry included consecutive patients who underwent surgery for acute type A aortic dissection (TAAD) at 18 European centers of cardiac surgery. Results: Data on arterial lactate concentration immediately before surgery were available in 2798 (71.7 %) patients. Preoperative concentration of arterial lactate was an independent predictor of in-hospital mortality (mean, 3.5 ± 3.2 vs 2.1 ± 1.8 mmol/L, adjusted OR 1.181, 95%CI 1.129-1.235). The best cutoff value preoperative arterial lactate concentration was 1.8 mmol/L (in-hospital mortality, 12.0 %, vs. 26.6 %, p < 0.0001). The rates of in-hospital mortality increased along increasing quintiles of arterial lactate and it was 12.1 % in the lowest quintile and 33.6 % in the highest quintile (p < 0.0001). The difference between multivariable models with and without preoperative arterial lactate was statistically significant (p = 0.0002). The NRI was 0.296 (95%CI 0.200-0.391) (p < 0.0001) with -17 % of events correctly reclassified (p = 0.0002) and 46 % of non-events correctly reclassified (p < 0.0001). The IDI was 0.025 (95%CI 0.016-0.034) (p < 0.0001). Six studies from a systematic review plus the present one provided data for a pooled analysis which showed that the mean difference of preoperative arterial lactate between 30-day/in-hospital deaths and survivors was 1.85 mmol/L (95%CI 1.22-2.47, p < 0.0001, I2 64 %). Conclusions: Hyperlactatemia significantly increased the risk of mortality after surgery for acute TAAD and should be considered in the clinical assessment of these critically ill patients.

Trypanosomes as a magnifying glass for cell and molecular biology.

The African trypanosome, Trypanosoma brucei, has developed into a flexible and robust experimental model for molecular and cellular parasitology, allowing us to better combat these and related parasites that cause worldwide suffering. Diminishing case numbers, due to efficient public health efforts, and recent development of new drug treatments have reduced the need for continued study of T. brucei in a disease context. However, we argue that this pathogen has been instrumental in revolutionary discoveries that have widely informed molecular and cellular biology and justifies continuing research as an experimental model. Ongoing work continues to contribute towards greater understanding of both diversified and conserved biological features. We discuss multiple examples where trypanosomes pushed the boundaries of cell biology and hope to inspire researchers to continue exploring these remarkable protists as tools for magnifying the inner workings of cells.

Deviating from the norm: Nuclear organisation in trypanosomes.

At first glance the nucleus is a highly conserved organelle. Overall nuclear morphology, the octagonal nuclear pore complex, the presence of peripheral heterochromatin and the nuclear envelope appear near constant features right down to the ultrastructural level. New work is revealing significant compositional divergence within these nuclear structures and their associated functions, likely reflecting adaptations and distinct mechanisms between eukaryotic lineages and especially the trypanosomatids. While many examples of mechanistic divergence currently lack obvious functional interpretations, these studies underscore the malleability of nuclear architecture. I will discuss some recent findings highlighting these facets within trypanosomes, together with the underlying evolutionary framework and make a call for the exploration of nuclear function in non-canonical experimental organisms.

Direct Aortic Versus Supra-Aortic Arterial Cannulation During Surgery for Acute Type A Aortic Dissection.

AIMS: In this study we evaluated the impact of direct aortic cannulation versus innominate/subclavian/axillary artery cannulation on the outcome after surgery for type A aortic dissection. METHODS: The outcomes of patients included in a multicenter European registry (ERTAAD) who underwent surgery for acute type A aortic dissection with direct aortic cannulation versus those with innominate/subclavian/axillary artery cannulation, i.e. supra-aortic arterial cannulation, were compared using propensity score matched analysis. RESULTS: Out of 3902 consecutive patients included in the registry, 2478 (63.5%) patients were eligible for this analysis. Direct aortic cannulation was performed in 627 (25.3%) patients, while supra-aortic arterial cannulation in 1851 (74.7%) patients. Propensity score matching yielded 614 pairs of patients. Among them, patients who underwent surgery for TAAD with direct aortic cannulation had significantly decreased in-hospital mortality (12.7% vs. 18.1%, p = 0.009) compared to those who had supra-aortic arterial cannulation. Furthermore, direct aortic cannulation was associated with decreased postoperative rates of paraparesis/paraplegia (2.0 vs. 6.0%, p < 0.0001), mesenteric ischemia (1.8 vs. 5.1%, p = 0.002), sepsis (7.0 vs. 14.2%, p < 0.0001), heart failure (11.2 vs. 15.2%, p = 0.043), and major lower limb amputation (0 vs. 1.0%, p = 0.031). Direct aortic cannulation showed a trend toward decreased risk of postoperative dialysis (10.1 vs. 13.7%, p = 0.051). CONCLUSIONS: This multicenter cohort study showed that direct aortic cannulation compared to supra-aortic arterial cannulation is associated with a significant reduction of the risk of in-hospital mortality after surgery for acute type A aortic dissection. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04831073.

A unique mRNA decapping complex in trypanosomes.

Removal of the mRNA 5' cap primes transcripts for degradation and is central for regulating gene expression in eukaryotes. The canonical decapping enzyme Dcp2 is stringently controlled by assembly into a dynamic multi-protein complex together with the 5'-3'exoribonuclease Xrn1. Kinetoplastida lack Dcp2 orthologues but instead rely on the ApaH-like phosphatase ALPH1 for decapping. ALPH1 is composed of a catalytic domain flanked by C- and N-terminal extensions. We show that T. brucei ALPH1 is dimeric in vitro and functions within a complex composed of the trypanosome Xrn1 ortholog XRNA and four proteins unique to Kinetoplastida, including two RNA-binding proteins and a CMGC-family protein kinase. All ALPH1-associated proteins share a unique and dynamic localization to a structure at the posterior pole of the cell, anterior to the microtubule plus ends. XRNA affinity capture in T. cruzi recapitulates this interaction network. The ALPH1 N-terminus is not required for viability in culture, but essential for posterior pole localization. The C-terminus, in contrast, is required for localization to all RNA granule types, as well as for dimerization and interactions with XRNA and the CMGC kinase, suggesting possible regulatory mechanisms. Most significantly, the trypanosome decapping complex has a unique composition, differentiating the process from opisthokonts.