First steps of bacteriophage SPP1 entry into Bacillus subtilis

The mechanism of genome transfer from the virion to the host cytoplasm is critical to understand and control the beginning of viral infection. The initial steps of bacteriophage SPP1 infection of the Gram-positive bacterium Bacillus subtilis were monitored by following changes in permeability of the cytoplasmic membrane (CM). SPP1 leads to a distinctively faster CM depolarization than the one caused by podovirus ?29 or myovirus SP01 during B. subtilis infection. Depolarization requires interaction of SPP1 infective virion to its receptor protein YueB. The amplitude of depolarization depends on phage input and concentration of YueB at the cell surface. Sub-millimolar concentrations of Ca^2 + are necessary and sufficient for SPP1 reversible binding to the host envelope and thus to trigger depolarization while DNA delivery to the cytoplasm depends on millimolar concentrations of this divalent cation. A model describing the early events of bacteriophage SPP1 infection is presented.     

Predictors of Procedural and Clinical Outcomes in Patients With Symptomatic Tricuspid Regurgitation Undergoing Transcatheter Edge-to-Edge Repair

Objectives

This study sought to investigate predictors of procedural success and clinical outcomes in patients with tricuspid regurgitation (TR) at increased surgical risk undergoing transcatheter tricuspid valve edge-to-edge repair (TTVR).

Sex-Related Clinical Characteristics and Outcomes of Patients Undergoing Transcatheter Edge-to-Edge Repair for Secondary Mitral Regurgitation

ObjectivesThe authors sought to assess sex-based differences in characteristics and outcomes of patients undergoing transcatheter edge-to-edge mitral valve repair (TMVR) for secondary mitral regurgitation (SMR).BackgroundSubgroup analysis from the COAPT (Cardiovascular Outcomes Assessment of the MitraClip Percutaneous Therapy for Heart Failure Patients with Functional Mitral Regurgitation) trial indicated potential sex-related differences in outcomes after TMVR. The impact of sex on results after TMVR in a real-world setting is unknown.MethodsThe authors assessed clinical outcomes and echocardiographic parameters in women and men undergoing TMVR for SMR between 2008 and 2018 who were included in the large, international, multicenter real-world EuroSMR registry (European Registry of Transcatheter Repair for Secondary Mitral Regurgitation).ResultsA total of 1,233 patients, including 445 women (36%) and 788 men (64%), were analyzed. Although women were significantly older and had fewer comorbidities than men, TMVR was equally effective in women and men (mitral regurgitation [MR] grade ≤2+ at discharge: 93.2% vs. 94.6% for women vs. men; p = 0.35). All-cause mortality at 1 year (17.9% vs. 18.9%, adjusted hazard ratio: 0.806; p = 0.46) and at 2-year follow-up (26.5% vs. 26.4%, adjusted hazard ratio: 0.757; p = 0.26) were similar in women versus men after multivariate regression analysis. Durability of MR reduction, improvement in symptoms, quality of life, and functional capacity did also not differ during follow-up.ConclusionsResults from the EuroSMR registry confirmed effective and similar MR reduction with TMVR in women and men. There were no sex-related differences in clinical outcomes up to 2 years of follow-up.     

Cardiopulmonary Hemodynamic Profile Predicts Mortality After Transcatheter Tricuspid Valve Repair in Chronic Heart Failure

ObjectivesThis study was designed to assess hemodynamic changes in response to transcatheter tricuspid valve edge-to-edge repair (TTVR) and to identify hemodynamic predictors associated with mortality.BackgroundSevere tricuspid regurgitation (TR) is associated with high mortality. TTVR effectively alleviates heart failure symptoms, but comprehensive hemodynamic characterization of patients undergoing TTVR is currently lacking.MethodsThis international, multicenter study included 236 patients undergoing TTVR. Data from clinical assessment, echocardiography, intraprocedural right heart catheterization, and noninvasive cardiac output measurement were analyzed. Hemodynamic predictors for mortality were identified using linear Cox regression analysis and were used for stratification of patients with subsequent analysis of survival time.ResultsPatients (median age 78 years, 53% women) were symptomatic (89% in New York Heart Association functional class III or IV) because of severe TR (grade ≥3+ in 100%). TTVR significantly reduced TR at discharge (grade ≥3+ in 16%; p < 0.001), with a corresponding 19% reduction of the right atrial v wave (21 mm Hg vs. 16 mm Hg; p < 0.001) and an improvement in cardiac output (from 3.5 to 4.0 l/min; p < 0.01). Invasive mean pulmonary artery pressure, transpulmonary gradient, pulmonary vascular resistance, and right ventricular stroke work were significant predictors of 1-year mortality (p < 0.05 for all). Hemodynamic stratification by mean pulmonary artery pressure and transpulmonary gradient best predicted 1-year survival (p < 0.001). Although patients with pre-capillary dominant pulmonary hypertension showed an unfavorable prognosis (1-year survival 38%), patients without or with post-capillary pulmonary hypertension had favorable outcome (1-year survival 92% or 78%, respectively).ConclusionsInvasive assessment of cardiopulmonary hemodynamic status predicts survival after TTVR. Invasive hemodynamic characterization may help identify patients profiting most from TTVR.     

Percutaneous pulmonary valve-in-valve implantation: a successful treatment concept for early device failure.

AIMS: Percutaneous pulmonary valve implantation (PPVI) is now an accepted treatment strategy for right ventricular (RV) outflow tract (RVOT) dysfunction in many European Heart Centres. We analysed the efficacy of repeat PPVI as a treatment modality for early device failure. METHODS AND RESULTS: Twenty patients underwent repeat PPVI for RVOT obstruction because of early device failure ('Hammock effect', 'Hammock-like effect', stent fracture, residual stenosis). Repeat PPVI was feasible in all patients with no procedural complications. Following implantation of a second device, catheter-measured RVOT gradient and RV systolic pressure fell significantly (RVOT gradient: 46.1 +/- 3.9 to 18.1 +/- 2.4 mmHg, P < 0.001; RVSP: 70.9 +/- 4.8 to 46.1 +/- 2.6 mmHg, P < 0.001), in all but one patient (15 years, male, common arterial trunk, 11.5 mm homograft). During follow-up, four of 20 required re-intervention [third PPVI for stent fracture (n = 2), device explantation: external compression by the sternum (n = 1), endocarditis (n = 1)], and one of the 20 is awaiting surgical management. In the remainder, second PPVI resulted in a sustained improvement in haemodynamics with a mean follow-up of 10.9 +/- 3.0 months. In this series, the probability of freedom from re-intervention at 2 years was higher after second PPVI when compared with the index procedure (89.4 vs. 20.0%, P < 0.001). CONCLUSION: Repeat PPVI is an effective treatment for early device failure in defined conditions and leads to improved freedom from re-intervention.     

In vitro assembly of relaxosomes at the transfer origin of plasmid RP4.

During initiation of conjugative transfer of DNA containing the transfer origin (oriT) of the promiscuous plasmid RP4, the proteins TraI, TraJ, and TraH interact and assemble a specialized nucleoprotein complex (the relaxosome) at oriT. The structure can be visualized on electron micrographs. Site- and strand-specific nicking at the transfer origin in vitro is dependent on the proteins TraI and TraJ and on Mg2+ ions. Substrate specificity is directed exclusively towards the cognate transfer origin: the RP4-specified TraJ protein cannot recognize the closely related oriT of plasmid R751. After nicking, TraI protein remains attached to the 5'-terminal 2'-deoxycytidyl residue at the nic site [Pansegrau, W., Ziegelin, G. & Lanka, E. (1990) J. Biol. Chem. 265, 10637-10644]. Nicking and relaxosome formation require supercoiled DNA. Thus, a complicated structure involving multiple plasmid-specified proteins and a defined region of DNA must be formed at the transfer origin to prepare the plasmid for generating the single strand to be transferred.     

Biological and physicochemical characterization of the major (1.40) and minor (1.45) component of infectious avian adeno-associated virus

Summary Two infectious components with buoyant densities of 1.40 g/cm³ and 1.45 g/cm³, designated as major (1.40) and minor (1.45) component, were detected by banding avian adeno-associated virus (AAAV) isopycnically in CsCl. In metrizamide, however, infectious AAAV banded only as a single peak at a density of 1.32 g/cm³. Biological as well as physicochemical properties of the two AAAV components recovered from CsCl density gradient were described. Concerning the minor (1.45) component, three experimental findings may suggest that the capsid structure of this AAAV population is altered in comparison with that of the major (1.40) component: (i) the sedimentation pattern characterized by an additional peak containing slower-sedimenting noninfectious material (16 S); (ii) the specific infectivity decreased by the 3.5 fold; (iii) the ready disintegration when exposed to gently denaturing conditions.