Endocrine adverse events in patients with cancer receiving perioperative immune checkpoint blockade: a meta-analysis of randomized controlled trials.

Background: Perioperative use of immune checkpoint blockade (ICB) improves survival in patients with early-stage cancer. Treatment-related adverse events (AEs), frequently involve the endocrine system which may increase perioperative complications and affect quality of life. Objective: We conducted a meta-analysis to elucidate the impact of adding ICB to conventional neoadjuvant/adjuvant therapy on the incidence of endocrine AEs. Design: A systematic review and meta-analysis of randomize-controlled trials (RCTs). Data sources and methods: A systematic search of PubMed, Embase, Web of Science, and Cochrane library was performed for RCTs comparing groups with and without the addition of ICB to conventional perioperative therapy in patients with cancer. Outcomes included all-grade and grade 3-5 thyroiditis, hyperthyroidism, hypothyroidism, adrenal insufficiency, hypophysitis, type 1 diabetes mellitus, and hyperglycemia. The odds ratios (ORs) of all-grade and grade 3-5 endocrine were pooled using the random-effect model meta-analysis. Results: Twenty-four RCTs comprising 12,199 patients were identified for meta-analysis. The addition of ICB was associated with higher incidence of thyroiditis [all grade: OR = 3.53 (95% confidence interval (CI): 1.88-6.64)], hyperthyroidism [all-grade: 7.18 (4.30-12.01); grade 3-5: 3.93 (1.21-12.82)], hypothyroidism [all-grade: 5.39 (3.68-7.90); grade 3-5: 3.63 (1.18-11.11)], adrenal insufficiency [all-grade: 3.82 (1.88-7.79); grade 3-5: 5.91 (2.36-14.82)], hypophysitis [all-grade: 10.29 (4.97-21.3); grade 3-5: 5.80 (1.99-16.92)], and type 1 diabetes mellitus [all-grade: 2.24 (1.06-4.74); grade 3-5: 3.49 (1.21-10.08)]. The cumulative incidence of each grade 3-5 endocrine AE was low (<1.3%). No grade 5 AEs leading to death were observed. Conclusion: The addition of neoadjuvant/adjuvant ICB to conventional therapy was associated with an increased incidence of several endocrine AEs. Clinicians should be aware of the risk of endocrinopathy from the perioperative ICB use to facilitate risk-benefit discussion with patients with early-stage cancer. Trial registration: The protocol of this research was registered in PROSPERO (CRD42022332624).

Invasive mussels fashion silk-like byssus via mechanical processing of massive horizontally acquired coiled coils.

Zebra and quagga mussels (Dreissena spp.) are invasive freshwater biofoulers that perpetrate devastating economic and ecological impact. Their success depends on their ability to anchor onto substrates with protein-based fibers known as byssal threads. Yet, compared to other mussel lineages, little is understood about the proteins comprising their fibers or their evolutionary history. Here, we investigated the hierarchical protein structure of Dreissenid byssal threads and the process by which they are fabricated. Unique among bivalves, we found that threads possess a predominantly ß-sheet crystalline structure reminiscent of spider silk. Further analysis revealed unexpectedly that the Dreissenid thread protein precursors are mechanoresponsive α-helical proteins that are mechanically processed into ß-crystallites during thread formation. Proteomic analysis of the byssus secretory organ and byssus fibers revealed a family of ultrahigh molecular weight (354 to 467 kDa) asparagine-rich (19 to 20%) protein precursors predicted to form α-helical coiled coils. Moreover, several independent lines of evidence indicate that the ancestral predecessor of these proteins was likely acquired via horizontal gene transfer. This chance evolutionary event that transpired at least 12 Mya has endowed Dreissenids with a distinctive and effective fiber formation mechanism, contributing significantly to their success as invasive species and possibly, inspiring new materials design.

A strong quick-release biointerface in mussels mediated by serotonergic cilia-based adhesion.

The mussel byssus stem provides a strong and compact mechanically mismatched biointerface between living tissue and a nonliving biopolymer. Yet, in a poorly understood process, mussels can simply jettison their entire byssus, rebuilding a new one in just hours. We characterized the structure and composition of the byssus biointerface using histology, confocal Raman mapping, phase contrast-enhanced microcomputed tomography, and advanced electron microscopy, revealing a sophisticated junction consisting of abiotic biopolymer sheets interdigitated between living extracellular matrix. The sheet surfaces are in intimate adhesive contact with billions of motile epithelial cilia that control biointerface strength and stem release through their collective movement, which is regulated neurochemically. We posit that this may involve a complex sensory pathway by which sessile mussels respond to environmental stresses to release and relocate.

Toxicity profiles of antibody-drug conjugates for anticancer treatment: a systematic review and meta-analysis.

BACKGROUND: Antibody-drug conjugates are attractive targeted agents in anticancer treatment because of their unique mechanism of action and reduced toxicity. Little is known about the spectrum of adverse events associated with antibody-drug conjugates, despite tens of clinical trials. METHODS: A systematic review of randomized controlled trials evaluating antibody-drug conjugate efficacy in anticancer treatment was conducted. PubMed, EMBASE, and ClinicalTrial.gov were searched for relevant studies. Meta-analyses assessed the odds ratios (ORs) of 12 treatment-related symptoms and toxicities in patients treated with antibody-drug conjugates compared with those receiving other anticancer agents without antibody-drug conjugates. All-grade and high-grade (grade ≥3) toxicities were examined. RESULTS: Twenty studies involving 10 075 patients were included. Compared with control groups, antibody-drug conjugates were associated with a higher risk of all-grade fatigue (OR = 1.25, 95% confidence interval [CI] = 1.08 to 1.45), anorexia (OR = 1.36, 95% CI = 1.09 to 1.69), nausea (OR = 1.46, 95% CI = 1.09 to 1.97), and sensory neuropathy (OR = 2.18, 95% CI = 1.27 to 3.76) as treatment-related symptoms. Patients treated with antibody-drug conjugates had a statistically significantly lower risk of all-grade febrile neutropenia (OR = 0.46, 95% CI = 0.22 to 0.96). Conversely, they had a higher risk of thrombocytopenia (OR = 2.07, 95% CI = 1.00 to 4.31), increased alanine aminotransferase (OR = 2.51, 95% CI = 1.84 to 3.40), and increased aspartate aminotransferase (OR = 2.83, 95% CI = 2.04 to 3.93). Subgroup analysis showed a similar toxicity profile when comparing the solid tumors with hematologic malignancy groups and the antibody-drug conjugate vs antibody-drug conjugate plus chemotherapy groups, except for some neurologic and hematologic adverse events. CONCLUSIONS: This comprehensive profile of adverse events associated with antibody-drug conjugate-based treatment shows an increase in various types of all-grade treatment-related symptoms and adverse events, although no increase in high-grade adverse events was seen.

Peculiar Phosphonate Modifications of Velvet Worm Slime Revealed by Advanced Nuclear Magnetic Resonance and Mass Spectrometry.

Nature is rich with examples of highly specialized biological materials produced by organisms for functions, including defense, hunting, and protection. Along these lines, velvet worms (Onychophora) expel a protein-based slime used for hunting and defense that upon shearing and dehydration forms fibers as stiff as thermoplastics. These fibers can dissolve back into their precursor proteins in water, after which they can be drawn into new fibers, providing biological inspiration to design recyclable materials. Elevated phosphorus content in velvet worm slime was previously observed and putatively ascribed to protein phosphorylation. Here, we show instead that phosphorus is primarily present as phosphonate moieties in the slime of distantly related velvet worm species. Using high-resolution nuclear magnetic resonance (NMR), natural abundance dynamic nuclear polarization (DNP), and mass spectrometry (MS), we demonstrate that 2-aminoethyl phosphonate (2-AEP) is associated with glycans linked to large slime proteins, while transcriptomic analyses confirm the expression of 2-AEP synthesizing enzymes in slime glands. The evolutionary conservation of this rare protein modification suggests an essential functional role of phosphonates in velvet worm slime and should stimulate further study of the function of this unusual chemical modification in nature.

pH-Responsive Reversible Granular Hydrogels Based on Metal-Binding Mussel-Inspired Peptides.

Taking advantage of their thixotropic behavior, microporosity, and modular properties, granular hydrogels formed from jammed hydrogel microparticles have emerged as an exciting class of soft, injectable materials useful for numerous applications, ranging from the production of biomedical scaffolds for tissue repair to the therapeutic delivery of drugs and cells. Recently, the annealing of hydrogel microparticles in situ to yield a porous bulk scaffold has shown numerous benefits in regenerative medicine, including tissue-repair applications. Current annealing techniques, however, mainly rely either on covalent connections, which produce static scaffolds, or transient supramolecular interactions, which produce dynamic but mechanically weak hydrogels. To address these limitations, we developed microgels functionalized with peptides inspired by the histidine-rich cross-linking domains of marine mussel byssus proteins. Functionalized microgels can reversibly aggregate in situ via metal coordination cross-linking to form microporous, self-healing, and resilient scaffolds at physiological conditions by inclusion of minimal amounts of zinc ions at basic pH. Aggregated granular hydrogels can subsequently be dissociated in the presence of a metal chelator or under acidic conditions. Based on the demonstrated cytocompatibility of these annealed granular hydrogel scaffolds, we believe that these materials could be developed toward applications in regenerative medicine and tissue engineering.

The Internal Structure of the Velvet Worm Projectile Slime: A Small-Angle Scattering Study.

For prey capture and defense, velvet worms eject an adhesive slime which has been established as a model system for recyclable complex liquids. Triggered by mechanical agitation, the liquid bio-adhesive rapidly transitions into solid fibers. In order to understand this mechanoresponsive behavior, here, the nanostructural organization of slime components are studied using small-angle scattering with neutrons and X-rays. The scattering intensities are successfully described with a three-component model accounting for proteins of two dominant molecular weight fractions and nanoscale globules. In contrast to the previous assumption that high molecular weight proteins-the presumed building blocks of the fiber core-are contained in the nanoglobules, it is found that the majority of slime proteins exist freely in solution. Only less than 10% of the slime proteins are contained in the nanoglobules, necessitating a reassessment of their function in fiber formation. Comparing scattering data of slime re-hydrated with light and heavy water reveals that the majority of lipids in slime are contained in the nanoglobules with homogeneous distribution. Vibrating mechanical impact under exclusion of air neither leads to formation of fibers nor alters the bulk structure of slime significantly, suggesting that interfacial phenomena and directional shearing are required for fiber formation.

Small Molecule-Templated DNA Hydrogel with Record Stiffness Integrates and Releases DNA Nanostructures and Gene Silencing Nucleic Acids.

Deoxyribonucleic acid (DNA) hydrogels are a unique class of programmable, biocompatible materials able to respond to complex stimuli, making them valuable in drug delivery, analyte detection, cell growth, and shape-memory materials. However, unmodified DNA hydrogels in the literature are very soft, rarely reaching a storage modulus of 103  Pa, and they lack functionality, limiting their applications. Here, a DNA/small-molecule motif to create stiff hydrogels from unmodified DNA, reaching 105  Pa in storage modulus is used. The motif consists of an interaction between polyadenine and cyanuric acid-which has 3-thymine like faces-into multimicrometer supramolecular fibers. The mechanical properties of these hydrogels are readily tuned, they are self-healing and thixotropic. They integrate a high density of small, nontoxic molecules, and are functionalized simply by varying the molecule sidechain. They respond to three independent stimuli, including a small molecule stimulus. These stimuli are used to integrate and release DNA wireframe and DNA origami nanostructures within the hydrogel. The hydrogel is applied as an injectable delivery vector, releasing an antisense oligonucleotide in cells, and increasing its gene silencing efficacy. This work provides tunable, stimuli-responsive, exceptionally stiff all-DNA hydrogels from simple sequences, extending these materials' capabilities.

Fabrication of Tunable Mechanical Gradients by Mussels via Bottom-Up Self-Assembly of Collagenous Precursors.

Functionally graded interfaces are prominent in biological tissues and are used to mitigate stress concentrations at junctions between mechanically dissimilar components. Biological mechanical gradients serve as important role models for bioinspired design in technically and biomedically relevant applications. However, this necessitates elucidating exactly how natural gradients mitigate mechanical mismatch and how such gradients are fabricated. Here, we applied a cross-disciplinary experimental approach to understand structure, function, and formation of mechanical gradients in byssal threads─collagen-based fibers used by marine mussels to anchor on hard surfaces. The proximal end of threads is approximately 50-fold less stiff and twice as extensible as the distal end. However, the hierarchical structure of the distal-proximal junction is still not fully elucidated, and it is unclear how it is formed. Using tensile testing coupled with video extensometry, confocal Raman spectroscopy, and transmission electron microscopy on native threads, we identified a continuous graded transition in mechanics, composition, and nanofibrillar morphology, which extends several hundreds of microns and which can vary significantly between individual threads. Furthermore, we performed in vitro fiber assembly experiments using purified secretory vesicles from the proximal and distal regions of the secretory glands (which contain different precursor proteins), revealing spontaneous self-assembly of distinctive distal- and proximal-like fiber morphologies. Aside from providing fundamental insights into the byssus structure, function, and fabrication, our findings reveal key design principles for bioinspired design of functionally graded polymeric materials.

Biological Materials Processing: Time-Tested Tricks for Sustainable Fiber Fabrication.

There is an urgent need to improve the sustainability of the materials we produce and use. Here, we explore what humans can learn from nature about how to sustainably fabricate polymeric fibers with excellent material properties by reviewing the physical and chemical aspects of materials processing distilled from diverse model systems, including spider silk, mussel byssus, velvet worm slime, hagfish slime, and mistletoe viscin. We identify common and divergent strategies, highlighting the potential for bioinspired design and technology transfer. Despite the diversity of the biopolymeric fibers surveyed, we identify several common strategies across multiple systems, including: (1) use of stimuli-responsive biomolecular building blocks, (2) use of concentrated fluid precursor phases (e.g., coacervates and liquid crystals) stored under controlled chemical conditions, and (3) use of chemical (pH, salt concentration, redox chemistry) and physical (mechanical shear, extensional flow) stimuli to trigger the transition from fluid precursor to solid material. Importantly, because these materials largely form and function outside of the body of the organisms, these principles can more easily be transferred for bioinspired design in synthetic systems. We end the review by discussing ongoing efforts and challenges to mimic biological model systems, with a particular focus on artificial spider silks and mussel-inspired materials.

Molecular characterization of accripin11, a soluble shell protein with an acidic C-terminus, identified in the prismatic layer of the Mediterranean fan mussel Pinna nobilis (Bivalvia, Pteriomorphia).

We have identified a novel shell protein, accripin11, as a major soluble component of the calcitic prisms of the fan mussel Pinna nobilis. Initially retrieved from a cDNA library, its full sequence is confirmed here by transcriptomic and proteomic approaches. The sequence of the mature protein is 103 residues with a theoretical molecular weight of 11 kDa and is moderately acidic (pI 6.74) except for its C-terminus which is highly enriched in aspartic acid. The protein exhibits a peculiar cysteine pattern in its central domain. The full sequence shares similarity with six other uncharacterized molluscan shell proteins from the orders Ostreida, Pteriida and Mytilida, all of which are pteriomorphids and produce a phylogenetically restricted pattern of nacro-prismatic shell microstructures. This suggests that accripin11 is a member of a family of clade-specific shell proteins. A 3D model of accripin11 was predicted with AlphaFold2, indicating that it possesses three short alpha helices and a disordered C-terminus. Recombinant accripin11 was tested in vitro for its ability to influence the crystallization of CaCO3 , while a polyclonal antibody was able to locate accripin11 to prismatic extracts, particularly in the acetic acid-soluble matrix. The putative functions of accripin11 are further discussed in relation to shell biomineralization.

Mussels Fabricate Porous Glues via Multiphase Liquid-Liquid Phase Separation of Multiprotein Condensates.

Mussels (Mytilus edulis) adhere to hard surfaces in intertidal marine habitats with a porous underwater glue called the byssus plaque. The plaque is an established role model for bioinspired underwater glues and comprises at least six proteins, most of which are highly cationic and enriched in the post-translationally modified amino acid 3,4-dihydroxyphenylalanine (DOPA). While much is known about the chemistry of plaque adhesion, less is understood about the natural plaque formation process. Here, we investigated plaque structure and formation using 3D electron microscopic imaging, revealing that micro- and nanopores form spontaneously during secretion of protein-filled secretory vesicles. To better understand this process, we developed a method to purify intact secretory vesicles for in vitro assembly studies. We discovered that each vesicle contains a sulfate-associated fluid condensate consisting of ∼9 histidine- and/or DOPA-rich proteins, which are presumably the required ingredients for building a plaque. Rupturing vesicles under specific buffering conditions relevant for natural assembly led to controlled multiphase liquid-liquid phase separation (LLPS) of different proteins, resulting in formation of a continuous phase with coexisting droplets. Rapid coarsening of the droplet phase was arrested through pH-dependent cross-linking of the continuous phase, producing native-like solid porous "microplaques" with droplet proteins remaining as fluid condensates within the pores. Results indicate that histidine deprotonation and sulfates figure prominently in condensate cross-linking. Distilled concepts suggest that combining phase separation with tunable cross-linking kinetics could be effective for microfabricating hierarchically porous materials via self-assembly.

Incidence of hepatotoxicity associated with addition of immune checkpoint blockade to systemic solid tumor therapy: a meta-analysis of phase 3 randomized controlled trials.

Hepatotoxicity is a major immune-related adverse event that may become life-threatening. The impact of adding immune checkpoint blockade (ICB) to systemic therapy on the incidence of hepatotoxicity remains unknown. We performed a systematic review and meta-analysis to compare the incidence of hepatotoxicity among patients with cancer who received therapy with and without addition of ICB. PubMed, Embase, Web of Science, and Cochrane Library were searched to select phase 3 randomized controlled trials (RCTs) evaluating the effect of adding ICB to systemic therapy, placebo, or supportive care. The odds ratio (OR) of any grade and grade 3-5 hepatitis, elevations in aspartate aminotransferase (AST), and alanine aminotransferase (ALT) was pooled for meta-analysis. 43 RCTs with 28,905 participants were analyzed. Addition of ICB increased the incidence of hepatitis (any grade: OR, 2.13, 95% confidence interval [CI] 1.52-2.97, grade 3-5: OR, 2.66, 95% CI 1.72-4.11), elevated AST (any grade: OR, 2.16, 95% CI 1.73-2.70, grade 3-5: OR, 2.72, 95% CI 1.86-3.99), and elevated ALT (any grade: OR, 2.01, 95% CI 1.59-2.54, grade 3-5: OR, 2.40, 95% CI 1.62-3.55). Subgroup analysis based on the ICB mechanism revealed no significant heterogeneity among each mechanism for hepatitis (any Grade: I2 = 11.1%, p for heterogeneity = 0.32, grade 3-5: I2 = 0%, p = 0.48). Adding ICB to systemic therapy increases the incidence of hepatotoxicity regardless of the mechanism of ICB. Hepatotoxicity is common and vigilant monitoring of liver function is required during ICB therapy for patients with cancer.

Extracellular Secretion and Simple Purification of Bacterial Collagen from Escherichia coli.

Because of structural similarities with type-I animal collagen, recombinant bacterial collagen-like proteins have been progressively used as a source of collagen for biomaterial applications. However, the intracellular expression combined with current costly and time-consuming chromatography methods for purification makes the large-scale production of recombinant bacterial collagen challenging. Here, we report the use of an adapted secretion pathway, used natively byEscherichia colito secrete curli fibers, for extracellular secretion of the bacterial collagen. We confirmed that a considerable fraction of expressed collagen (∼70%) is being secreted freely into the extracellular medium, with an initial purity of ∼50% in the crude culture supernatant. To simplify the purification of extracellular collagen, we avoided cell lysis and used cross-flow filtration or acid precipitation to concentrate the voluminous supernatant and separate the collagen from impurities. We confirmed that the secreted collagen forms triple helical structures, using Sirius Red staining and circular dichroism. We also detected collagen biomarkers via Raman spectroscopy, further supporting that the recombinant collagen forms a stable triple helical conformation. We further studied the effect of the isolation methods on the morphology and secondary structure, concluding that the final collagen structure is process-dependent. Overall, we show that the curli secretion system can be adapted for extracellular secretion of the bacterial collagen, eliminating the need for cell lysis, which simplifies the collagen isolation process and enables a simple cost-effective method with potential for scale-up.

Mistletoe viscin: a hygro- and mechano-responsive cellulose-based adhesive for diverse material applications.

Mistletoe viscin is a natural cellulosic adhesive consisting of hierarchically organized cellulose microfibrils (CMFs) surrounded by a humidity-responsive matrix that enables mechanical drawing into stiff and sticky fibers. Here, we explored the processability and adhesive capacity of viscin and demonstrated its potential as a source material for various material applications, as well as a source for bioinspired design. Specifically, we revealed that viscin fibers exhibit humidity-activated self-adhesive properties that enable "contact welding" into complex 2D and 3D architectures under ambient conditions. We additionally discovered that viscin can be processed into stiff and transparent free-standing films via biaxial stretching in the hydrated state, followed by drying, whereby CMFs align along local stress fields. Furthermore, we determined that viscin adheres strongly to both synthetic materials (metals, plastics, and glass) and biological tissues, such as skin and cartilage. In particular, skin adhesion makes viscin a compelling candidate as a wound sealant, as we further demonstrate. These findings highlight the enormous potential of this hygro- and mechano-responsive fiber-reinforced adhesive for bioinspired and biomedical applications.

Microfluidic-like fabrication of metal ion-cured bioadhesives by mussels.

To anchor in seashore habitats, mussels fabricate adhesive byssus fibers that are mechanically reinforced by protein-metal coordination mediated by 3,4-dihydroxyphenylalanine (DOPA). The mechanism by which metal ions are integrated during byssus formation remains unknown. In this study, we investigated the byssus formation process in the blue mussel, Mytilus edulis, combining traditional and advanced methods to identify how and when metals are incorporated. Mussels store iron and vanadium ions in intracellular metal storage particles (MSPs) complexed with previously unknown catechol-based biomolecules. During adhesive formation, stockpiled secretory vesicles containing concentrated fluid proteins are mixed with MSPs within a microfluidic-like network of interconnected channels where they coalesce, forming protein-metal bonds within the nascent byssus. These findings advance our understanding of metal use in biological materials with implications for next-generation metallopolymers and adhesives.

From vesicles to materials: bioinspired strategies for fabricating hierarchically structured soft matter.

Certain organisms including species of mollusks, polychaetes, onychophorans and arthropods produce exceptional polymeric materials outside their bodies under ambient conditions using concentrated fluid protein precursors. While much is understood about the structure-function relationships that define the properties of such materials, comparatively less is understood about how such materials are fabricated and specifically, how their defining hierarchical structures are achieved via bottom-up assembly. Yet this information holds great potential for inspiring sustainable manufacture of advanced polymeric materials with controlled multi-scale structure. In the present perspective, we first examine recent work elucidating the formation of the tough adhesive fibres of the mussel byssus via secretion of vesicles filled with condensed liquid protein phases (coacervates and liquid crystals)-highlighting which design principles are relevant for bio-inspiration. In the second part of the perspective, we examine the potential of recent advances in drops and additive manufacturing as a bioinspired platform for mimicking such processes to produce hierarchically structured materials. This article is part of the theme issue 'Bio-derived and bioinspired sustainable advanced materials for emerging technologies (part 1)'.

Practical considerations for using K3 cameras in CDS mode for high-resolution and high-throughput single particle cryo-EM.

Detector technology plays a pivotal role in high-resolution and high-throughput cryo-EM structure determination. Compared with the first-generation, single-electron counting direct detection camera (Gatan K2), the latest K3 camera is faster, larger, and now offers a correlated-double sampling mode (CDS). Importantly this results in a higher DQE and improved throughput compared to its predecessor. In this study, we focused on optimizing camera data collection parameters for daily use within a cryo-EM facility and explored the balance between throughput and resolution. In total, eight data sets of murine heavy-chain apoferritin were collected at different dose rates and magnifications, using 9-hole image shift data collection strategies. The performance of the camera was characterized by the quality of the resultant 3D reconstructions. Our results demonstrated that the Gatan K3 operating in CDS mode outperformed standard (nonCDS) mode in terms of reconstruction resolution in all tested conditions with 8 electrons per pixel per second being the optimal dose rate. At low magnification (64kx) we were able to achieve reconstruction resolutions of 149% of the physical Nyquist limit (1.8 Å with a 1.346 Å physical pixel size). Low magnification allows more particles to be collected per image, aiding analysis of heterogeneous samples requiring large data sets. At moderate magnification (105kx, 0.834 Å physical pixel size) we achieved a resolution of 1.65 Å within 8-h of data collection, a condition optimal for achieving high-resolution on well behaved samples. Our results also show that for an optimal sample like apoferritin, one can achieve better than 2.5 Å resolution with 5 min of data collection. Together, our studies validate the most efficient ways of imaging protein complexes using the K3 direct detector and will greatly benefit the cryo-EM community.

Impact of Surgical and Transcatheter Aortic Valve Replacement in Low-Gradient Aortic Stenosis: A Meta-Analysis.

OBJECTIVES: The aim of this study was to assess the impact of aortic valve replacement (AVR) on survival in patients with each subclass of low-gradient (LG) aortic stenosis (AS) and to compare outcomes following surgical AVR (SAVR) and transcatheter AVR (TAVR). BACKGROUND: LG severe AS encompasses a wide variety of pathophysiology, including classical low-flow, LG (LF-LG), paradoxical LF-LG, and normal-flow, LG (NF-LG) AS, and uncertainty exists regarding the impact of AVR on each subclass of LG AS. METHODS: PubMed and Embase were queried through October 2020 to identify studies comparing survival with different management strategies (SAVR, TAVR, and conservative) in patients with LG AS. Pairwise meta-analysis comparing AVR versus conservative management and network meta-analysis comparing SAVR versus TAVR versus conservative management were performed. RESULTS: Thirty-two studies with a total of 6,515 patients and a median follow-up time of 24.2 months (interquartile range: 36.5 months) were included. AVR was associated with a significant decrease in all-cause mortality in classical LF-LG (hazard ratio [HR]: 0.42; 95% confidence interval [CI]: 0.36 to 0.48), paradoxical LF-LG (HR: 0.41; 95% CI: 0.29 to 0.57), and NF-LG (HR: 0.41; 95% CI: 0.27 to 0.62) AS compared with conservative management. SAVR and TAVR were each associated with a decrease in all-cause mortality in classical LF-LG (HR: 0.46 [95% CI: 0.38 to 0.55] and 0.49 [95% CI: 0.37 to 0.64], respectively), paradoxical LF-LG (HR: 0.42 [95% CI: 0.28 to 0.65] and 0.42 [95% CI: 0.25 to 0.72], respectively), and NF-LG (HR: 0.40 [95% CI: 0.21 to 0.77] and 0.46 [95% CI: 0.26 to 0.84], respectively) AS compared with conservative management. No significant difference was observed between SAVR and TAVR. CONCLUSIONS: In all subclasses of LG AS, AVR was associated with a significant decrease in all-cause mortality regardless of surgical or transcatheter approach.

Collagen Pentablock Copolymers Form Smectic Liquid Crystals as Precursors for Mussel Byssus Fabrication.

Protein-based biological materials are important role models for the design and fabrication of next generation advanced polymers. Marine mussels (Mytilus spp.) fabricate hierarchically structured collagenous fibers known as byssal threads via bottom-up supramolecular assembly of fluid protein precursors. The high degree of structural organization in byssal threads is intimately linked to their exceptional toughness and self-healing capacity. Here, we investigated the hypothesis that multidomain collagen precursor proteins, known as preCols, are stored in secretory vesicles as a colloidal liquid crystal (LC) phase prior to thread self-assembly. Using advanced electron microscopy methods, including scanning TEM and FIB-SEM, we visualized the detailed smectic preCol LC nanostructure in 3D, including various LC defects, confirming this hypothesis and providing quantitative insights into the mesophase structure. In light of these findings, we performed an in-depth comparative analysis of preCol protein sequences from multiple Mytilid species revealing that the smectic organization arises from an evolutionarily conserved ABCBA pentablock copolymer-like primary structure based on demarcations in hydropathy and charge distribution as well as terminal pH-responsive domains that trigger fiber formation. These distilled supramolecular assembly principles provide inspiration and strategies for sustainable assembly of nanostructured polymeric materials for potential applications in engineering and biomedical applications.