Point mutations in SARS-CoV-2 variants induce long-range dynamical perturbations in neutralizing antibodies.

Monoclonal antibodies are emerging as a viable treatment for the coronavirus disease 19 (COVID-19). However, newly evolved variants of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can reduce the efficacy of currently available antibodies and can diminish vaccine-induced immunity. Here, we demonstrate that the microscopic dynamics of neutralizing monoclonal antibodies can be profoundly modified by the mutations present in the spike proteins of the SARS-COV-2 variants currently circulating in the world population.

Transcatheter Tricuspid Valve Implantation of NaviGate Bioprosthesis in a Preclinical Model.

Patients with isolated functional or recurrent tricuspid regurgitation are often denied surgery because they are considered to be at high risk. Transcatheter valve therapy provides a less invasive alternative for tricuspid regurgitation associated with right heart failure. We have evaluated the feasibility of transcatheter tricuspid valve implantation of the NaviGate valved stent in a long-term swine model.

Transcatheter mitral valve replacement with the NaviGate stent in a preclinical model.

Aims: The aim of this study was to test the feasibility of transcatheter mitral valve implantation of the NaviGate device in acute and chronic preclinical models.

Methods And Results: We evaluated NaviGate valved stent implantation in the mitral position in an acute swine model (n=24, ≤5 days) through three different approaches - transatrial, transapical, and transseptal - and in a chronic swine model (n=12, >10 days) through a transatrial approach. The NaviGate implantation procedures were successful in 83% of the acute model studies (n=20) and 83% of the chronic model studies (n=10).

A nosocomial outbreak of norovirus infection masquerading as clostridium difficile infection.

Noroviruses (NoVs) are increasingly being recognized as important enteric pathogens. At a university-based hospital, we investigated a nosocomial outbreak of NoV infection that was originally attributed to Clostridium difficile. We describe here the unique challenges of the identification of NoVs as the true etiologic pathogen in an outbreak occurring in a health care setting, where C.

Tubular heart valves: a new tissue prosthesis design--preclinical evaluation of the 3F aortic bioprosthesis.

Background: It was hypothesized that native heart valves function as if they were simple tubes with sides that collapse when external pressure is applied. Because "form follows function," this hypothesis could theoretically be confirmed by implanting a simple tube into the anatomic position of any native heart valve and documenting that under the same anatomic constraints and physiologic conditions as the native valve, the tube would assume the form of that native valve. If the hypothesis were thus proved, it would follow that a tissue valve based on a tubular design would have superior flow dynamics and stress distribution and would therefore be expected to outlast currently available tissue valves.

Tagging morphogenetic genes by insertional mutagenesis in the yeast Yarrowia lipolytica.

The yeast Yarrowia lipolytica is distantly related to Saccharomyces cerevisiae, can be genetically modified, and can grow in both haploid and diploid states in either yeast, pseudomycelial, or mycelial forms, depending on environmental conditions. Previous results have indicated that the STE and RIM pathways, which mediate cellular switching in other dimorphic yeasts, are not required for Y. lipolytica morphogenesis.

Risk assessment in a third-world reality: an endosulfan case history.

The author describes the chain of frustrated attempts to regulate the use of the toxic pesticide endosulfan in the Philippines in the face of opposition from its internationally powerful manufacturer. Risk assessment, although purportedly a science-based system to protect public health and the environment, has failed to do so, particularly in vulnerable third-world countries. The precautionary principle, based on preventing risk rather than assessing established risk, holds hope for resolution of the problem.

Fluid dynamics of venous valve closure.

In vitro experiment was performed on a stented bovine jugular vein valve (VV, 14 mm I.D. x 2 cm long) and a stentless bovine jugular vein valve conduit (10 mm I.

In vitro pulsatile flow evaluation of a stentless porcine aortic bioprosthesis.

Suboptimal hemodynamic performance, tissue calcification, and limitation in long-term durability have been encountered clinically after aortic valve replacement with currently available bioprostheses. It is believed that some of these problems may be caused, directly or indirectly, by the stents of the bioprostheses. To address these deficiencies, the authors undertook the development of the Edwards Prima Stentless Bioprosthesis.

The closing velocity of mechanical heart valve leaflets.

The closing motion of the occluder leaflets in bileaflet type mechanical heart valves (MHV) was monitored with a laser sweeping technique. The angular displacements of the leaflets were registered with precision of 0.2 microsecond steps.

Characterization of a polyepoxy compound fixed porcine heart valve bioprosthesis.

Concerns with the currently available bioprostheses are calcification, long-term durability, and suboptimal hemodynamic performance. It is well known that these concerns are all more or less related to the cross-linking reagent, glutaraldehyde or formaldehyde, used in fixing bioprostheses. To address these concerns, we undertook the development of a porcine bioprosthesis fixed with a polyepoxy compound.

Fixation of bioprosthetic tissues with monofunctional and multifunctional polyepoxy compounds.

Collagen from a native tissue is fixed with a polyepoxy compound (PC) for use as a new biologic prosthetic material. Prior studies have shown that this biomaterial has comparable properties with collagen fixed with glutaraldehyde (GA), and thus has great promise for biomedical applications. A prior kinetic study indicated that the reaction between the functional groups of collagen and the multifunctional epoxy EX-313 is a 2.

A newly developed porcine heart valve bioprosthesis fixed with an epoxy compound. An experimental evaluation.

Concerns with currently available bioprostheses are calcification, long-term durability, and functional and hemodynamic performance. It has been well known that these concerns are all more or less related to the fixatives, glutaraldehyde or formaldehyde, used in preserving bioprostheses. To address these concerns, we undertook the development of a porcine bioprosthesis fixed with an epoxy compound.

Neural net-bootstrap hybrid methods for prediction of complications in patients implanted with artificial heart valves.

A novel hybrid methodology for prediction of valve related complications in patients with implanted artificial heart valves is discussed. Artificial neural networks provided a mechanism for prediction of postoperative valve-related deaths based on preoperative patient information and valve parameters. Then bootstrap methodology was applied for estimating prediction errors and maximizing prediction accuracy.

Hemodynamic evaluation of a bioprosthetic venous prosthesis.

Purpose: A prosthetic venous valve must be biocompatible and nonthrombogenic and function in the venous circulation. Biocompatibility and thrombogenicity of our prosthesis have been examined in prior animal experiments, and 91% of valve conduits including early prototypes are patent at 3 weeks. However, evaluation of valve function is much more difficult in animals; therefore in this study the function of excised valves was evaluated ex vivo.

Prediction of valve-related complications for artificial heart valves using adaptive neural networks: a preliminary study.

A novel approach to the prediction of valve-related complications in patients with implanted artificial heart valves is discussed. Adaptive artificial neural networks were used to identify patients at high risk of valve-related events based on preoperative data. Data from a clinical trial on 789 subjects with Carpentier-Edwards pericardial bioprostheses were used.

A preliminary study of the fixation mechanism of collagen reaction with a polyepoxy fixative.

A new biomaterial has been developed by fixing native collagens with a polyepoxy compound (PC) fixative. Prior studies have shown that this biomaterial has comparable properties as compared to collagen fixed with glutaraldehyde (GA) and thus has a great promise for use as an implantable bioprosthesis. The purpose of this study was to understand the mechanism of the amino acids-PC reactions in the fixation process.

Evaluation of collagen modification and surface properties of a bovine artery via polyepoxy compound fixation.

Collagen of bovine internal thoracic artery (BITA) was treated with glutaraldehyde (GA) or polyepoxy compounds (PC). This study was to evaluate the surface properties as a result of tissue tanning reaction with PC. The fixation resulted in a significant reduction of available lysine, histidine, and other amino acid residues in PC fixed grafts as compared to fresh pre-fixed arteries.

Cavitation threshold with respect to dP/dt: evaluation in 29 mm bileaflet, pyrolitic carbon heart valves.

A total of 15 bileaflet mechanical heart valves were studied in a pulse duplicator at the Helmholtz Institute (Aachen, Germany) under conditions approximating first, a physiological pressure curve and subsequently, a sinusoidal pressure curve. In this study Edwards-Duromedics valves of the modified specification were compared with the earlier version of the Edwards-Duromedics valve as well as with St. Jude Medical valves.

A comparative study of complement activation by Denaflex, Bioflow, and BioPolyMeric vascular grafts.

This study was performed to evaluate the degree of complement activation by three bovine arterial graft materials: Bioflow (Bio-Vascular Inc., a bovine artery fixed with dialdehyde starch), BioPolyMeric (St. Jude Medical Inc.

Comparison of the cross-linking characteristics of porcine heart valves fixed with glutaraldehyde or epoxy compounds.

The concerns about currently available bioprosthetic heart valves are calcification, long-term durability, and functional and hemodynamic performance. These concerns are all more or less related to the cross-linking reagents, glutaraldehyde or formaldehyde, used in fixing bioprostheses. To address these concerns, the authors undertook the development of a porcine heart valve cross-linked with an epoxy compound.

Development and evaluation of a pliable biological valved conduit. Part II: Functional and hemodynamic evaluation.

Many congenital cardiac malformations may require a valved conduit for the reconstruction of the right ventricular outflow tract. In spite of many endeavors made in the last 25 years, the clinical results of right ventricular outflow tract reconstruction with currently available valved conduits are still not satisfactory. Specific problems encountered clinically include suboptimal hemodynamic performance, conduit kinking or compression, and fibrous peeling from the luminal surface.

Evaluation of epoxy ether fixed bovine arterial grafts for mutagenic potential.

Two epoxy ether compounds [glycerol polyglycidyl ether (Denacol EX-313) and ethylene glycol diglycidyl ether (Denacol EX-810)] are under consideration as alternatives to glutaraldehyde for use in the processing of an arterial graft. The two are utilized as cross-linking and sterilant agents, respectively. Epoxy resins are multifunctional alkylating agents, and bifunctional alkylating epoxide solutions are known to be mutagenic.