Regioselective addition of DDQ on a quinoid ring: an entry into chiral zwitterionic bridging ligands

International audienceThe regioselective insertion of DDQ into a C-H bond of the 6π + 6π electron zwitterionic benzoquinonemonoimines 4a-c results in the formation of the novel chiral C-substituted quinoid ligands 11a-c. These Michael adducts feature a preserved zwitterionic form and a quaternary stereogenic carbon center as evidenced by the single crystal X-ray structure of the derivative 11a. The ECD spectra, optical rotations and racemization barriers of the two enantiomers of 11a were measured subsequently to their separation by a preparative chiral HPLC. Because the racemization of 11a is stopped in basic media, compounds 11a-c give a new entry in chiral zwitterionic bridging ligands

073 Right Ventricle Contractile Reserve as a Pre-operative Tool for Assessing RV failure after Continuous Flow LVAD Implantation

IntroductionLatest generation continuous flow left ventricular assist devices (LVADs) have been proposed as an alternative to heart transplantation for end-stage heart failure. However, postoperative right ventricle (RV) dysfunction remains common and has a negative impact on prognosis. Purpose of our study was to identify echocardiographic or hemodynamic parameters that could predict early RV failure after LVAD implantation in patients with biventricular dysfunction.MethodsFourteen patients with biventricular dysfunction who have been evaluated for LVAD implantation were included. Right and left ventricular dysfunction were respectively defined as: tricuspid annular plane excursion < 16 mm (TAPSE) and LV ejection fraction < 35%. In all patients, preoperative measurements were obtained at rest. In 7 patients, right heart catheterization was performed simultaneously with increasing doses of dobutamine (15γ/Kg/min). Primary endpoint was death caused by right ventricle systolic dysfunction or need for right ventricle mechanical support within 30 days after surgery (RVSD+).ResultsMean recipient age was 58±7 years. Primary end-point (RVSD+) was noted in five patients. Preoperative demographic, echocardiographic and hemodynamic data were similar between RVSD+ and RVSD- patients (Table). Percent increase of TAPSE and systolic PAP between basal and high dobutamine dose was significantly lower in RVSD+ than in RVSD- patients.ConclusionPercent increase of TAPSE and systolic PAP induced by high dose dobutamine infusion might be two interesting criteria to assess RV contractile reserve and predict RV outcome after LVAD implantation in patient with biventricular dysfunction.Baseline Measurement (n=14)Change after Dobutamine infusion,% (n=7)RVSD-RVSD+pRVSD-RVSD+pN95TAPSE, mm14±214±20.955±526±20.03Systolic PAP, mmHg51±753±60.842±84±70.05Cardiac Output, l/min3.3±0.53.5±0.50.987±1093±470.7Pulm Vasc Res, Wood3.9±14.3±10.62±41-36±70.

Generation of cattle knockout for galactose‐α1,3‐galactose and N‐glycolylneuraminic acid antigens

Two well-characterized carbohydrate epitopes are absent in humans but present in other mammals. These are galactose-α1,3-galactose (αGal) and N-glycolylneuraminic acid (Neu5Gc) which are introduced by the activities of two enzymes including α(1,3) galactosyltransferase (encoded by the GGTA1 gene) and CMP-Neu5Gc hydroxylase (encoded by the CMAH gene) that are inactive in humans but present in cattle. Hence, bovine-derived products are antigenic in humans who receive bioprosthetic heart valves (BHVs) or those that suffer from red meat syndrome. Using programmable nucleases, we disrupted (knockout, KO) GGTA1 and CMAH genes encoding for the enzymes that catalyse the synthesis of αGal and Neu5Gc, respectively, in both male and female bovine fibroblasts. The KO in clonally selected fibroblasts was detected by polymerase chain reaction (PCR) and confirmed by Sanger sequencing. Selected fibroblasts colonies were used for somatic cell nuclear transfer (SCNT) to produce cloned embryos that were implanted in surrogate recipient heifers. Fifty-three embryos were implanted in 33 recipients heifers; 3 pregnancies were carried to term and delivered 3 live calves. Primary cell cultures were established from the 3 calves and following molecular analyses confirmed the genetic deletions. FACS analysis showed the double-KO phenotype for both antigens confirming the mutated genotypes. Availability of such cattle double-KO model lacking both αGal and Neu5Gc offers a unique opportunity to study the functionality of BHV manufactured with tissues of potentially lower immunogenicity, as well as a possible new clinical approaches to help patients with red meat allergy syndrome due to the presence of these xenoantigens in the diet

Differential Immune Response to Bioprosthetic Heart Valve Tissues in the α1,3Galactosyltransferase-Knockout Mouse Model

Structural valve deterioration (SVD) of bioprosthetic heart valves (BHVs) has great clinical and economic consequences. Notably, immunity against BHVs plays a major role in SVD, especially when implanted in young and middle-aged patients. However, the complex pathogenesis of SVD remains to be fully characterized, and analyses of commercial BHVs in standardized-preclinical settings are needed for further advancement. Here, we studied the immune response to commercial BHV tissue of bovine, porcine, and equine origin after subcutaneous implantation into adult a1,3-galactosyltransferase-knockout (Gal KO) mice. The levels of serum anti-galactose a1,3-galactose (Gal) and -non-Gal IgM and IgG antibodies were determined up to 2 months post-implantation. Based on histological analyses, all BHV tissues studied triggered distinct infiltrating cellular immune responses that related to tissue degeneration. Increased anti-Gal antibody levels were found in serum after ATS 3f and Freedom/Solo implantation but not for Crown or Hancock II grafts. Overall, there were no correlations between cellular-immunity scores and post-implantation antibodies, suggesting these are independent factors differentially affecting the outcome of distinct commercial BHVs. These findings provide further insights into the understanding of SVD immunopathogenesis and highlight the need to evaluate immune responses as a confounding factor

Characterization of immunogenic Neu5Gc in bioprosthetic heart valves

Background: The two common sialic acids (Sias) in mammals are N-acetylneuraminic acid (Neu5Ac) and its hydroxylated form N-glycolylneuraminic acid (Neu5Gc). Unlike most mammals, humans cannot synthesize Neu5Gc that is considered foreign and recognized by circulating antibodies. Thus, Neu5Gc is a potential xenogenic carbohydrate antigen in bioprosthetic heart valves (BHV) that tend to deteriorate in time within human patients. Methods: We investigated Neu5Gc expression in non-engineered animal-derived cardiac tissues and in clinically used commercial BHV, and evaluated Neu5Gc immunogenicity on BHV through recognition by human anti-Neu5Gc IgG. Results: Neu5Gc was detected by immunohistochemistry in porcine aortic valves and in porcine and bovine pericardium. Qualitative analysis of Sia linkages revealed Siaa2-3> Siaa2-6 on porcine/bovine pericardium while the opposite in porcine aortic/pulmonary valve cusps. Similarly, six commercial BHV containing either porcine aortic valve or porcine/bovine/equine pericardium revealed Siaa2-3> Siaa2-6 expression. Quantitative analysis of Sia by HPLC showed porcine/bovine pericardium express 4-fold higher Neu5Gc levels compared to the porcine aortic/pulmonary valves, with Neu5Ac at 6-fold over Neu5Gc. Likewise, Neu5Gc was expressed on commercial BHV (186.3 +/- 16.9 pmol Sia/mu g protein), with Neu5Ac at 8-fold over Neu5Gc. Affinity-purified human anti-Neu5Gc IgG showing high specificity toward Neu5Gc-glycans (with no binding to Neu5Ac-glycans) on a glycan microarray, strongly bound to all tested commercial BHV, demonstrating Neu5Gc immune recognition in cardiac xenografts. Conclusions: We conclusively demonstrated Neu5Gc expression in native cardiac tissues, as well as in six commercial BHV. These Neu5Gc xeno-antigens were recognized by human anti-Neu5Gc IgG, supporting their immunogenicity. Altogether, these findings suggest BHV-Neu5Gc/anti-Neu5Gc may play a role in valve deterioration warranting further investigation

Oxidative Stress in Structural Valve Deterioration : A Longitudinal Clinical Study

The cause of structural valve deterioration (SVD) is unclear. Therefore, we investigated oxidative stress markers in sera from patients with bioprosthetic heart valves (BHVs) and their association with SVD. Blood samples were taken from SVD (Phase A) and BHV patients during the first 24 (Phase B1) and >48 months (Phase B2) after BHV implantation to assess total antioxidant capacity (TAC), malondialdehyde (MDA), and nitrotyrosine (NT). The results show that MDA levels increased significantly 1 month after surgery in all groups but were higher at 6 months only in incipient SVD patients. NT levels increased gradually for the first 24 months after implantation in the BHV group. Patients with transcatheter aortic valve implantation (TAVI) showed even higher levels of stress markers. After >48 months, MDA and NT continued to increase in BHV patients with a further elevation after 60-72 months; however, these levels were significantly lower in the incipient and established SVD groups. In conclusion, oxidative stress may play a significant role in SVD, increasing early after BHV implantation, especially in TAVI cases, and also after 48 months' follow-up, but decreasing when SVD develops. Oxidative stress potentially represents a target of therapeutic intervention and a biomarker of BHV dysfunctio

Durability of bioprosthetic aortic valve replacement in patients under the age of 60 years - 1-year follow-up from the prospective INDURE registry.

OBJECTIVES We report 1-year safety and clinical outcomes in patients <60 years undergoing bioprosthetic surgical aortic valve intervention. METHODS The INSPIRIS RESILIA Durability Registry (INDURE) is a prospective, multicentre registry to assess clinical outcomes of patients <60 years. Patients with planned SAVR with or without concomitant replacement of the ascending aorta and/or coronary bypass surgery were included. Time-related valve safety, haemodynamic performance, and quality of life (QoL) at 1 year were assessed. RESULTS 421 patients were documented with a mean age of 53.5 years, 76.5% being male, and 27.2% in NYHA class III/IV. Outcomes within 30 days included cardiovascular-related mortality (0.7%), time-related valve safety (VARC-2; 5.8%), thromboembolic events (1.7%), valve-related life-threatening bleeding (VARC-2; 4.3%), and permanent pacemaker implantation (3.8%). QoL was significantly increased at 6 months and sustained at 1 year. Freedom from all-cause mortality at 1 year was 98.3% (95%CI 97.1;99.6) and 81.8% were NYHA I vs. 21.9% at baseline. No patient developed structural valve deterioration Stage 3 (VARC-3). Mean aortic pressure gradient was 12.6 mmHg at 1 year and effective orifice area was 1.9 cm2. CONCLUSIONS The 1-year data from the INSPIRIS RESILIA valve demonstrate good safety and excellent haemodynamic performance as well as an early QoL improvement. CLINICALTRIALS NUMBER NCT03666741

Genome sequence of the stramenopile Blastocystis, a human anaerobic parasite

International audienceABSTRACT: BACKGROUND: Blastocystis is a highly prevalent anaerobic eukaryotic parasite of humans and animals that is associated with various gastrointestinal and extraintestinal disorders. Epidemiological studies have identified different subtypes but no one subtype has been definitively correlated with disease. RESULTS: Here we report the 18.8 Mb genome sequence of a Blastocystis subtype 7 isolate, which is the smallest stramenopile genome sequenced to date. The genome is highly compact and contains intriguing rearrangements. Comparisons with other available stramenopile genomes (plant pathogenic oomycete and diatom genomes) revealed effector proteins potentially involved in the adaptation to the intestinal environment, which were likely acquired via horizontal gene transfer. Moreover, Blastocystis living in anaerobic conditions harbors mitochondria-like organelles. An incomplete oxidative phosphorylation chain, a partial Krebs cycle, amino acid and fatty acid metabolisms and an iron-sulfur cluster assembly are all predicted to occur in these organelles. Predicted secretory proteins possess putative activities that may alter host physiology, such as proteases, protease-inhibitors, immunophilins and glycosyltransferases. This parasite also possesses the enzymatic machinery to tolerate oxidative bursts resulting from its own metabolism or induced by the host immune system. CONCLUSIONS: This study provides insights into the genome architecture of this unusual stramenopile. It also proposes candidate genes with which to study the physiopathology of this parasite and thus may lead to further investigations into Blastocystis-host interactions

Durability of bioprosthetic aortic valves in patients under the age of 60 years - Rationale and design of the international INDURE registry

Background: There is an ever-growing number of patients requiring aortic valve replacement (AVR). Limited data is available on the long-term outcomes and structural integrity of bioprosthetic valves in younger patients undergoing surgical AVR. Methods: The INSPIRIS RESILIA Durability Registry (INDURE) is a prospective, open-label, multicentre, international registry with a follow-up of 5 years to assess clinical outcomes of patients younger than 60 years who undergo surgical AVR using the INS

Trends in SAVR with biological vs. mechanical valves in middle-aged patients: results from a French large multi-centric survey

Background/introductionCurrently, despite continued issues with durability ( 1), biological prosthetic valves are increasingly chosen over mechanical valves for surgical aortic valve replacement (SAVR) in adult patients of all ages, at least in Western countries. For younger patients, this choice means assuming the risks associated with a redo SAVR or valve-in-valve procedure.PurposeTo assess the use of mechanical vs. biological valve prostheses for SAVR relative to patient's age and implant time in a large population extracted from the French National Database EPICARD.MethodsPatients in EPICARD undergoing SAVR from 2007 to 2022 were included from 22 participating public or private centers chosen to represent a balanced representation of centre sizes and geographical discrepancies. Patients with associated pathology of the aorta (aneurysm or dissection) and requiring a vascular aortic prosthesis were excluded. Comparisons were made amongst centers, valve choice, implant date range, and patient age.ResultsWe considered 101,070 valvular heart disease patients and included 72,375 SAVR (mean age 71.4 ± 12.2 years). We observed a mechanical vs. biological prosthesis ratio (MBPR) of 0.14 for the overall population. Before 50 years old (y-o), MBPR was &gt;1.3 (p &lt; 0.001) while patients above 60 years-old received principally biological SAVR (p &lt; 0.0001). Concerning patients between 50 and 60 years-old patients, MPVR was 1.04 (p = 0.03). Patients 50–60 years-old from the first and second study duration quartile (before August 2015) received preferentially mechanical SAVR (p &lt; 0.001). We observed a shift towards more biological SAVR (p &lt; 0.001) for patients from the third and fourth quartile to reach a MBPR at 0.43 during the last years of the series. Incidentally, simultaneous mitral valve replacement were more common in case of mechanical SAVR (p &lt; 0.0001), while associated CABGs were more frequent in case of biological SAVR (p &lt; 0.0001).ConclusionIn a large contemporary French patient population, real world practice showed a recent shift towards a lower age-threshold for biological SAVR as compared to what would suggest contemporary guidelines