Versatile de novo enzyme activity in capsid proteins from an engineered M13 bacteriophage library.

Biocatalysis has grown rapidly in recent decades as a solution to the evolving demands of industrial chemical processes. Mounting environmental pressures and shifting supply chains underscore the need for novel chemical activities, while rapid biotechnological progress has greatly increased the utility of enzymatic methods. Enzymes, though capable of high catalytic efficiency and remarkable reaction selectivity, still suffer from relative instability, high costs of scaling, and functional inflexibility. Herein, we developed a biochemical platform for engineering de novo semisynthetic enzymes, functionally modular and widely stable, based on the M13 bacteriophage. The hydrolytic bacteriophage described in this paper catalyzes a range of carboxylic esters, is active from 25 to 80 °C, and demonstrates greater efficiency in DMSO than in water. The platform complements biocatalysts with characteristics of heterogeneous catalysis, yielding high-surface area, thermostable biochemical structures readily adaptable to reactions in myriad solvents. As the viral structure ensures semisynthetic enzymes remain linked to the genetic sequences responsible for catalysis, future work will tailor the biocatalysts to high-demand synthetic processes by evolving new activities, utilizing high-throughput screening technology and harnessing M13's multifunctionality.

Bothsiderism.

This paper offers an account of a fallacy we will call bothsiderism, which is to mistake disagreement on an issue for evidence that either a compromise on, suspension of judgment regarding, or continued discussion of the issue is in order. Our view is that this is a fallacy of a unique and heretofore untheorized type, a fallacy of meta-argumentation. The paper develops as follows. After a brief introduction, we examine a recent bothsiderist case in American politics. We use this as a pivot point to survey the theoretical literature on the fallacy. The most prominent theory is that bothsiderism is a case of dialogue-shifting. This view fails, we maintain, to explain how bothsiderism might be persuasive. We argue, rather, bothsiderism is a kind of meta-argumentative fallacy.

Ex vivo comparison of three surgical techniques to stabilize canine cranial cruciate ligament deficient stifles.

OBJECTIVE: To quantify and compare canine stifle stability after 3 stabilization techniques. STUDY DESIGN: Randomized controlled study. SAMPLE POPULATION: Adult canine cadaveric pelvic limbs. METHODS: Total craniocaudal (CrCa) tibial translation quantified in stifles with the cranial cruciate ligament (CrCL) intact, transected, and stabilized with 1 of 3 techniques: (1) hamstring graft (HG); (2) modified retinacular imbrication (MRIT); (3) anatometric fascia lata translocation (AFLT). Tibial translation was quantified from radiographs generated during application of cranial and caudal forces to the tibia. After removal of all soft tissues except periarticular ligaments and fixation, CrCa tibial translation, as before, and medial-lateral rotation, via torsional loading, was quantified with an active motion analysis system. Total tibial translation was evaluated for effect of technique and cruciate status using mixed effect linear model with significance considered at P-value <.05. RESULTS: CrCa translation was not significantly different across stabilization techniques with CrCLs intact, transected, or after stabilization. Poststabilization translation was significantly less than posttransection for all techniques. Compared with the intact CrCL, CrCa translation poststabilization after HG was significantly greater whereas poststabilization after MRIT and AFLT was not significantly different. Tibial rotation exceeded instrumentation limits in 62.5% HG limbs, 20% MRIT limbs, and 60% AFLT limbs. CONCLUSIONS: All 3 stifle stabilization techniques confer comparable CrCa translational stability after CrCL disruption with that provided by the MRIT and AFLT techniques comparable to the intact CrCL. CLINICAL RELEVANCE: The extra- and intracapsular techniques evaluated in this study reduced CrCa tibial translation in CrCL deficient stifles to varying amounts.

Biomechanical characteristics of an implant used to secure semitendinosus-gracilis tendon grafts in a canine model of extra-articular anterior cruciate ligament reconstruction.

OBJECTIVE: To compare initial femoral fixation properties of a new implant, Graftgrab (GG), with 2 established methods of extra-articular femoral graft fixation, spiked washers (SW) and bone staples (ST). STUDY DESIGN: Experimental in vitro cohort study. METHODS: Canine semitendinosus-gracilis tendon grafts were passed through bone tunnels and fixed to the lateral surface of femoral condyles with spiked washers, bone staples, or new implant prototypes. The fixations were tested to failure with a single-cycle load at a rate of 50 mm/min. Failure and yield strength, stiffness, energy, and elongation were determined from load-displacement curves and failure modes were recorded. RESULTS: The graft failed midsubstance in 4 SW, 4 ST, and 1 GG fixations. In 3 SW, 3 ST, and 1 GG specimens, the graft slipped from the fixation. The graft ruptured at the clip (3) and the intra-articular (2) surface of the bone tunnel in the remaining GG specimens. There were no significant differences between fixation groups in femoral tunnel length, femoral width, or the mechanical properties evaluated. CONCLUSIONS: The initial in vitro mechanical properties of the new fixation implant are comparable with those of spiked washers and bone staples. CLINICAL RELEVANCE: The initial mechanical performance of the new implant tested in this study was similar to those of comparable, established implants. The new implant is novel and may be useful for human anterior and veterinary cranial cruciate ligament graft reconstruction fixation.

Caged siRNAs for spatiotemporal control of gene silencing.

Various strategies have been employed to achieve control over delivery of siRNA molecules to intended target cells. Photocaging is one specific class of modifications for silencing oligonucleotides that block their bioactivity until exposure to near-ultraviolet light. These caged RNAi effectors enable both spatial and temporal targeting of a dosed release of gene silencing agents by directed light exposure that photocleaves the cage moieties. Herein we compare the photochemical properties of cage compounds and strategies for their use, attached either randomly or site-specifically, to demonstrate various forms of gene expression regulation in vitro and in vivo. This light-controllable strategy has potential applications for precisely probing developing biological systems and eventually enabling targeted gene-silencing therapeutics.

Chirality-resolved length analysis of single-walled carbon nanotube samples through shear-aligned photoluminescence anisotropy.

An efficient new method is demonstrated for measuring length distributions of semiconducting single-walled carbon nanotubes (SWCNTs) through analysis of their highly polarized photoluminescence when aligned by shear flows. Instrumentation and procedures are developed to characterize nanotube lengths in bulk suspensions with rapid data acquisition and interpretation. Applying the method with spectrally resolved SWCNT emission provides the first measurements of (n,m)-specific length distributions. A positive correlation is found between average length and nanotube diameter, although this correlation is weaker following extensive sample centrifugation. Intense sonication shortened all nanotube species and had the strongest effect on those with small diameters. The new method should provide a useful alternative to atomic force microscopy for characterizing SWCNT lengths.

A numerical optimization approach to acoustic hull array design.

A numerical optimization approach is presented to optimize passive broadband detection performance of hull arrays through the adjustment of array shading weights. The approach is developed for general hull arrays in low signal-to-noise ratio scenarios, and is shown to converge rapidly to optimal solutions that maximize the array's deflection coefficient. The beamformer is not redesigned in this approach; only the shading weights of the conventional beamformer are adjusted. This approach allows array designers to use the array to minimize the impact of known sources of noise on detection at the beamformer output while maintaining acoustic array gain against an unknown source. The technique is illustrated through numerical examples using hull-borne structural noise as the noise source; however, the design concept can be applied to other design parameters of the array such as element position, material selection, etc.