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Cadherin-based adherens junctions and desmosomes help stabilize cell-cell contacts with additional function in mechano-signaling, while clustered protocadherin junctions are responsible for directing neuronal circuits assembly. Structural models for adherens junctions formed by epithelial cadherin (CDH1) proteins indicate that their long, curved ectodomains arrange to form a periodic, two-dimensional lattice stabilized by tip-to-tip trans interactions (across junction) and lateral cis contacts. Less is known about the exact architecture of desmosomes, but desmoglein (DSG) and desmocollin (DSC) cadherin proteins are also thought to form ordered junctions. In contrast, clustered protocadherin (PCDH) based cell-cell contacts in neuronal tissues are thought to be responsible for self-recognition and avoidance, and structural models for clustered PCDH junctions show a linear arrangement in which their long and straight ectodomains form antiparallel overlapped trans complexes. Here we report all-atom molecular dynamics simulations testing the mechanics of minimalistic adhesive junctions formed by CDH1, DSG2 coupled to DSC1, and PCDHγB4, with systems encompassing up to 3.7 million atoms. Simulations generally predict a favored shearing pathway for the adherens junction model and a two-phased elastic response to tensile forces for the adhesive adherens junction and the desmosome models. Complexes within these junctions first unbend at low tensile force and then become stiff to unbind without unfolding. However, cis interactions in both the CDH1 and DSG2-DSC1 systems dictate varied mechanical responses of individual dimers within the junctions. Conversely, the clustered protocadherin PCDHγB4 junction lacks a distinct two-phased elastic response. Instead, applied tensile force strains trans interactions directly as there is little unbending of monomers within the junction. Transient intermediates, influenced by new cis interactions, are observed after the main rupture event. We suggest that these collective, complex mechanical responses mediated by cis contacts facilitate distinct functions in robust cell-cell adhesion for classical cadherins and in self-avoidance signaling for clustered PCDHs.Statement of SignificanceProteins that mediate cell-cell contacts often form aggregates in vivo where the tight packing of monomers into junctions is relevant to their function. Members of the cadherin superfamily of glycoproteins form large complexes in which their long ectodomains interact to mediate cell-cell adhesion. Here, we employ simulations to elucidate complex mechanical responses of five junction systems in response to force. Our results offer atomistic insights into the behavior of these proteins in a crowded physiological context, suggesting that classical cadherin complexes in adherens junctions and desmosomes act as molecular shock absorbers with responses modulated by dynamic lateral contacts, while clustered protocadherins form brittle junctions that upon stretching and unbinding form transient interfaces suitable for their critical role in neuronal self-recognition.

Peptidoglycan—a mesh sac of glycans that are linked by peptides—is the main component of bacterial cell walls. Peptidoglycan provides structural strength, protects cells from osmotic pressure and contributes to shape. All bacterial glycans are repeating disaccharides of N-acetylglucosamine (GlcNAc) β-(1–4)-linked to N-acetylmuramic acid (MurNAc). Borrelia burgdorferi, the tick-borne Lyme disease pathogen, produces glycan chains in which MurNAc is occasionally replaced with an unknown sugar. Nuclear magnetic resonance, liquid chromatography–mass spectroscopy and genetic analyses show that B. burgdorferi produces glycans that contain GlcNAc–GlcNAc. This unusual disaccharide is chitobiose, a component of its chitinous tick vector. Mutant bacteria that are auxotrophic for chitobiose have altered morphology, reduced motility and cell envelope defects that probably result from producing peptidoglycan that is stiffer than that in wild-type bacteria. We propose that the peptidoglycan of B. burgdorferi probably evolved by adaptation to obligate parasitization of a tick vector, resulting in a biophysical cell-wall alteration to withstand the atypical torque associated with twisting motility., Tick chitobiose is co-opted to build the cell wall of Lyme disease pathogen Borrelia burgdorferi.

The mechanistic enzymology of oxidoreductases has contributed to the development of therapeutics, biomimetic synthetic catalysts, and engineered enzymes with improved or emergent function. Acquirin...

Surface modification is a main approach for natural polymers to gain flame retardancy. Developing a green coating system to endow natural polymers with flame retardancy and wash-durability is extremely challenging. Herein, a sandwich-like structured nanocoating system with mutual restricted network through electrostatic interaction, hydrogen bonding, and chemical bonding were designed via multi-layered coating and UV curing. The coated natural cotton fabrics demonstrated exellent flame retardancy, wash durability, and hydrophobicity. The chemicals involved include montmorillonite (MMT), ammonium polyphosphate (APP), acrylated polyurethane (PU), branched polyethylenimine (bPEI), and polydimethylsiloxane (PDMS). The concentration of bPEI governed the wash durability of the coated fabrics, and those samples with a higher concentration of bPEI possessed better wash durability. Meanwhile, bPEI served as a flammable resource to deteriorate the flame retardant performance. The systematic evaluations of the coated fabrics after washing demonstrated that this coating system can maintain balanced wash durability and flame retardancy.

A one-pot self-assembled nanocoating with a well-defined nanostructure was created consisting of polyvinyl alcohol (PVA) and montmorillonite (MMT) and applied to double-walled corrugated cardboard (CB) via spray coating. X-ray diffraction (XRD) analysis revealed the intercalation of PVA into the interstitial spaces of the MMT nanosheets and the alignment of the nanosheets. Vertical burning test, surface burning test, and horizontal burning test showed marked reductions in afterflame time, afterglow time, and flame spread, displaying quick self-extinguishing behaviors. Scanning electron microscopy (SEM) images revealed a uniform coating of the surface of CB before burning tests. After burning, the coated CB samples formed a dense char layer that protected the underlying fibers. A PVA/MMT nanocoating applied via spray coating greatly inhibited flame spread and improved flame retardancy. A one-pot coassembled nanocoating consisting of polyvinyl alcohol and montmorillonite was developed to significantly improve the flame retardancy of cardboard.

An efficient and convergent (4+1)-cycloaddition strategy toward the construction of spirooxindole benzofurans that involves the intermediacy of an isatin-derived oxyphosphonium enolate is presented. Mechanistic investigations employing in situ NMR analysis of the reaction mixture revealed a correlation between phosphonium enolate structure and product distribution that was heavily influenced by the solvent and reaction temperature.

The leukocyte nucleus must be sufficiently elastic to squeeze through tissue barriers during migration, but not so collapsible as to risk damaging chromatin. The proper balance is struck in part by the composition of the nuclear lamina, a flexible meshwork composed mainly of intermediate filaments woven from type A and type B lamin proteins, that is located subjacent to the inner nuclear membrane. There is now increasing evidence that, in addition to influencing nuclear shape and stiffness and cell migration, lamins and lamin-interacting proteins may also interact functionally with chromatin to influence leukocyte gene expression, differentiation, and effector function, including T cell differentiation, B cell somatic hypermutation, and the formation of neutrophil extracellular traps (NETosis).

A phosphorus(III)-mediated dearomatization of ortho-substituted dianiline squaraine dyes results in an unusual skeletal rearrangement to provide exotic, highly conjugated benzofuranone and oxindole scaffolds bearing a C3 side chain comprised of a linear conflagration of an enol, a phosphorus ylide, and 2,4-disubstituted aniline. Employing experimental and computational analysis, a mechanistic evaluation revealed a striking dependence on the acidity of the aniline ortho substituent. Notably, the rearrangement adducts underwent rapid and complete reversion to the parent squaraine in the presence of a Brønsted acid.

The synthesis and structural, electrochemical, spectroscopic, and magnetic characterizations of CrIII(HMC) catecholate and semiquinonate complexes are reported herein, where HMC is 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane. cis-[Cr(HMC)(Cat)]+ complexes (Cat = catecholate, [1]+; tetrachlorocatecholate, [2]+; and 3,5-di-tert-butylcatecholate, [3]+) were prepared from the reaction between appropriate catechol and [CrIII(HMC)Cl2]Cl reduced in situ by zinc. Chemical oxidation of [3]+ by FcPF6 resulted in cis-[Cr(HMC)(SQ)]2+ ([3]2+, SQ = 3,5-di-tert-butylsemiquinonate). Single crystal X-ray diffraction studies revealed the cis-chelation of the Cat/SQ ligand around the Cr metal center and confirmed the Cat/SQ nature of the ligands. Reversible oxidations of Cat to SQ were observed in the cyclic voltammograms of [1]+-[3]+, while the CrIII center remains redox inactive. The absorption spectrum of the SQ complex [3]2+ exhibits an intense spin-forbidden transition in solution. Time-delayed phosphorescence spectra recorded at 77 K revealed that all catecholate complexes emit from the 2E state, while [2]+ also emits from the 2T1 state. Temperature-dependent magnetic susceptibility measurements indicate the Cat complexes exist as S = 3/2 systems, while the SQ complex behaves as an S = 1 system, resulting from strong antiferromagnetic coupling of the S = 3/2 Cr center with the S = 1/2 SQ radical. Density functional theory (DFT) shows the similarities between the SOMOs of [1]+ and [2]+ and differences in their LUMOs in the ground state.

Formaldehyde (HCHO), formed in situ by transfer dehydrogenation of methanol in methanol-to-hydrocarbon (MTH) conversion, reacts with other organic species including olefins, dienes, and aromatics t...

(4+1)-Cyclizations are an underutilized disconnect for the formation of five-membered heterocyclic and carbocyclic frameworks. Herein we analyze methods employing oxyphosphonium enolates and RhII/PdII-metallocarbenes as C1 synthons in the presence of several four-atom components for the synthesis of 2,3-dihydrobenzofurans, 2,3-dihydroindoles, oxazolones, cyclopentenones, and pyrrolones.1 Introduction2 (4+1)-Cyclizations Employing Kukhtin–Ramirez-Like Reactivity3 (4+1)-Cyclizations Employing a Cyclopropanation/Ring-Expansion Sequence4 Pd-Catalyzed (4+1)-Cyclizations through Carbene Migratory Insertion/Reductive Elimination Processes5 Summary

Seawater desalination plays a critical role in addressing the global water shortage challenge. Directional Solvent Extraction (DSE) is an emerging non-membrane desalination technology that features the ability to utilize very low temperature waste heat (as low as 40 °C). This is enabled by the subtly balanced solubility properties of directional solvents, which do not dissolve in water but can dissolve water and reject salt ions. However, the low water yield of the state-of-the-art directional solvent (decanoic acid) significantly limits its throughput and energy efficiency. In this paper, we demonstrate that by using ionic liquid as a new directional solvent, saline water can be desalinated with much higher production rate and thus significantly lower the energy and exergy consumptions. The ionic liquid identified suitable for DSE is [emim][Tf2N], which has a much (~10×) higher water yield than the currently used decanoic acid. Using molecular dynamics simulations with Gibbs free energy calculations, we reveal that water dissolving in [emim][Tf2N] is energetically favorable, but it takes significant energy for [emim][Tf2N] ions to dissolve in water. Our findings may significantly advance the DSE technology as a solution to the challenges in the global water-energy nexus., Directional Solvent Extraction is an emerging non-membrane desalination technology for sea water desalination but is limited by throughput and energy efficiency. Here, the authors demonstrate that the production rate and energy efficiency can be increased by using ionic liquids as directional solvent.

Adducts of the parent iminoborane isomers, HBNH and NBH2, have been prepared, each stabilized by the frustrated Lewis pair (FLP) chelate iPr2P(C6H4)BCy2 (PB). PB{HBNH} was accessed via dehydrohalogenation, while the corresponding isomer PB{NBH2} was obtained from the borylation of the formal nitrene-FLP complex PB{NH}.

Polymer synthesis routes result in macromolecules with molecular weight dispersity ĐM that depends on the polymerization mechanism. The lowest dispersity polymers are those made by anionic and atom...

Objective This study tests the elution capabilities of a magnesium phosphate cement (MPC). Study objectives were to quantify the passive release of magnesium ions from MPC and to assess the effects of antibiotic-loaded MPC on bacterial growth and osteoblast viability. Methods MPC constructs were created and incubated in fetal bovine serum (FBS). At 2, 4, and 17 weeks, a sample was collected for magnesium ion concentration analysis. Control and vancomycin-loaded (vanc) MPC beads were also created. Zone of inhibition was measured after incubating beads on Staphylococcus aureus agar plates for 24 h. Osteoblasts were seeded onto control and vanc beads and cultured for 9 days. Metabolic activity was measured via a resazurin assay. ANOVA with Tukey HSD post-hoc tests and t-tests were performed. Results Magnesium ions were eluted at 2 and 4-week time points without significant difference, but demonstrated a significant spike at the 17-week time point. Zones of inhibition for the bacterial species was observed for Vanc-MPC beads, but not control beads. No cytotoxic effects on osteoblasts were noted. Conclusion MPC has potential to improve bone regeneration based on its ability to passively elute magnesium. Additionally, antibiotic-loaded MPC inhibits bacterial growth while avoiding osteoblast cytotoxicity.

Significance When sound vibrations reach the inner ear, fine protein filaments called “tip links” stretch and open cochlear hair-cell mechanosensitive channels that trigger sensory perception. Similarly, vestibular hair cells use tip links to sense mechanical stimuli produced by head motions. Tip links are formed by cadherin-23 and protocadherin-15, two large proteins involved in hearing loss and balance disorders. Here we present multiple structures, models, and simulations that depict the lower end of the tip link, including the complete protocadherin-15 ectodomain. These models show an essential connection between cadherin-23 and protocadherin-15 with dual molecular “handshakes” and various protein sites that are mutated in inherited deafness. The simulations also reveal how the tip link responds to force to mediate hearing and balance sensing., The vertebrate inner ear, responsible for hearing and balance, is able to sense minute mechanical stimuli originating from an extraordinarily broad range of sound frequencies and intensities or from head movements. Integral to these processes is the tip-link protein complex, which conveys force to open the inner-ear transduction channels that mediate sensory perception. Protocadherin-15 and cadherin-23, two atypically large cadherins with 11 and 27 extracellular cadherin (EC) repeats, are involved in deafness and balance disorders and assemble as parallel homodimers that interact to form the tip link. Here we report the X-ray crystal structure of a protocadherin-15 + cadherin-23 heterotetrameric complex at 2.9-Å resolution, depicting a parallel homodimer of protocadherin-15 EC1-3 molecules forming an antiparallel complex with two cadherin-23 EC1-2 molecules. In addition, we report structures for 10 protocadherin-15 fragments used to build complete high-resolution models of the monomeric protocadherin-15 ectodomain. Molecular dynamics simulations and validated crystal contacts are used to propose models for the complete extracellular protocadherin-15 parallel homodimer and the tip-link bond. Steered molecular dynamics simulations of these models suggest conditions in which a structurally diverse and multimodal protocadherin-15 ectodomain can act as a stiff or soft gating spring. These results reveal the structural determinants of tip-link–mediated inner-ear sensory perception and elucidate protocadherin-15’s structural and adhesive properties relevant in disease.

The net rate of a composite reaction is the difference between the forward and reverse reaction rates, which are kinetically distinct despite sharing elementary reaction steps and therefore have different rate-controlling transition states and species. Thus, degrees of rate control defined to identify rate-controlling transition states and species for the net rate confound contributions from the forward and reverse reactions. Herein, the forward and reverse degrees of rate control are defined to independently quantify the extent that species and transition states control the forward and reverse rates in reversible reactions. These degrees of rate control are defined as the relative change in the forward and reverse reaction rates per k B T decrease in the standard-state molecular free energies of transition states and species, and they are related to experimentally measurable quantities such as steady-state fractional coverages, reaction orders, and energies and entropies of activation of the forward and reverse reaction rates. The forward/reverse degrees of rate control represent stoichiometric coefficients for species and transition states in an equilibrium between the initial states and transition states of the apparent rate-controlling steps of forward and reverse overall reactions. At equilibrium, the apparent transition states for the forward reaction and reverse reaction converge, and thus the forward and reverse rate-controlling steps combine to form a single apparent rate-controlling step. This apparent rate-controlling step is comprised of an apparent initial state, transition state, and final state, where the apparent final state of the forward reaction is the apparent initial state of the reverse reaction. The apparent rate-controlling step behaves identically to an elementary step reaction at equilibrium with a pseudo-mass-action rate function given by the transition-state-theory (TST) form rate function (Foley and Bhan, 2020) with a stoichiometric number equal to the affinity-averaged stoichiometric number, σ ¯ . The ratio of the forward and reverse TST-form rate functions is identical to the overall thermodynamic equilibrium relation, consistent with the principles of microscopic reversibility and detailed balance at equilibrium.

A combined steady-state and transient kinetic study on the mechanism of diphenylmethane (DPM) formation in HZSM-5 from HCHO and benzene revealed two kinetically relevant steps—the alkylation of ben...

A Pd0-catalyzed formal (4 + 1)-cycloaddition approach to 2,3-disubstituted dihydroindoles is described. The diastereoselective formation of dihydroindoles that is highlighted by a carbene migratory...

Reported herein are the syntheses and characterizations for a series of butadiyndiyl-bridged CoIII(MPC) (MPC = 5,12-dimethyl-7,14-diphenyl-1,4,8,11-tetraazacyclotetradecane) complexes, capped with ...

Antibiotic resistance is a significant and growing public health problem. This work investigated the use of two different carbon nanomaterials, single-walled carbon nanotubes (SWNTs) and nanographe...

We describe sensitivities of elementary steps as salient parameters in determining the rate determining character of elementary steps within a reaction network and develop a formalism wherein the overall composite reaction is described by an apparent rate-determining step that is a sensitivity-weighted average of the elementary steps that comprise the reaction network. Reaction parameters—apparent reaction orders, apparent enthalpy and entropy of activation—of the composite reaction network are determined within the framework we develop by application of transition state theory to the apparent rate-determining step. From this formalism we develop methods for determination of surface coverages by measuring only reaction orders, methods for discrimination between proposed mechanisms, a proof that the kinetic degrees of rate control sum to unity, and a proof for the relationship between fractional coverages and thermodynamic degrees of rate control. Two complementary formalisms for identifying rate-limiting transition states are broadly employed in chemical kinetics—De Donder relations based on assessing the thermodynamic driving forces of elementary steps during reaction and degrees of rate control based on knowledge of the kinetics of elementary reaction steps. The formalism developed herein unifies these two strategies to elucidate in the most general case a relationship between the thermodynamic driving forces of elementary steps captured by the reversibilities and the kinetic and thermodynamic degrees of rate control.

Complement evasion is a hallmark of extracellular microbial pathogens such as Borrelia burgdorferi, the causative agent of Lyme disease. Lyme disease spirochetes express nearly a dozen outer surface lipoproteins that bind complement components and interfere with their native activities. Among these, BBK32 is unique in its selective inhibition of the classical pathway. BBK32 blocks activation of this pathway by selectively binding and inhibiting the C1r serine protease of the first component of complement, C1. To understand the structural basis for BBK32-mediated C1r inhibition, we performed crystallography and size-exclusion chromatography–coupled small angle X-ray scattering experiments, which revealed a molecular model of BBK32-C in complex with activated human C1r. Structure-guided site-directed mutagenesis was combined with surface plasmon resonance binding experiments and assays of complement function to validate the predicted molecular interface. Analysis of the structures shows that BBK32 inhibits activated forms of C1r by occluding substrate interaction subsites (i.e., S1 and S1’) and reveals a surprising role for C1r B loop–interacting residues for full inhibitory activity of BBK32. The studies reported in this article provide for the first time (to our knowledge) a structural basis for classical pathway–specific inhibition by a human pathogen.

Metal release rates were measured from four different copper alloy-based materials used by the aquaculture industry: copper sheet machined into a diamond mesh, copper alloy mesh (CAM), silicon bronze welded wire mesh, and copper sheeting, and compared with conventional nylon aquaculture net treated with a cuprous oxide antifouling (AF) coating. Release rates were measured

Development of new electrosynthetic chemistry promises to impact the efficiency and sustainability of organic synthesis. Here we demonstrate that anodically generated hypervalent iodine intermediates effectively couple interfacial electron transfer with oxidative C-H/N-H coupling chemistry. The developed hypervalent iodine electrocatalysis is applicable in both intra- and intermolecular C-N bond-forming reactions. Available mechanistic data indicate that anodic oxidation of aryl iodides generates a transient I(II) intermediate that is critically stabilized by added acetate ions. This report represents the first example of metal-free hypervalent iodine electrocatalysis for C-H functionalization and provides mechanistic insight that we anticipate will contribute to the development of hypervalent iodine mediators for synthetic electrochemistry.

Summary Reversible multi-color chromic systems are critical for the development of advanced sensors, encryption devices, and rewritable media. While many systems show chromic responses to applied stimuli, few show distinct multi-colored states within the same system and exhibit limited flexibility in manipulation of the stimuli source. Light-responsive materials have shown promise because of high precision and controllable parameters of the incident light but suffer from slow kinetics limiting the versatility of the photochromic systems. Here, we report a highly active oxygen vacant titanium oxide/reduced graphene oxide photocatalyst that significantly accelerates the color switching of commercial redox dyes. With the improved catalyst, four photochromic devices are realized: (1) multi-wavelength photochromism, (2) intensity-dependent photochromism, (3) time-dependent photochromism, and (4) dual-response hydro-/photochromism. These devices are based on manipulating the interactions between the light and semiconductor and exhibit a broad range of photochromic behaviors with multi-color states and high reversibility.

To provide an up-to-date synopsis of the literature on the safety of sunscreen active ingredients in humans and the environment and highlight regulatory changes in the USA. Currently, as per the US Food and Drug Administration, the only ultraviolet filters generally recognized as safe and effective are inorganic zinc oxide (ZnO) and titanium dioxide (TiO2). In vivo human systemic absorption studies found that common organic filters attain sufficient plasma concentrations to require carcinogenicity and reproductive studies. In vivo human skin penetration studies showed ZnO nanoparticles (ZnO-NP) did not penetrate the stratum corneum. Limited quantities of TiO2-NP may be absorbed systemically. In laboratory settings, corals exposed to oxybenzone manifested concentration-dependent toxicity and bleaching. In response, bills passed in Hawaii and elsewhere ban sales of oxybenzone-containing sunscreens. ZnO-NP, but not TiO2-NP, caused coral bleaching under controlled conditions. The collective knowledge on sunscreen safety is continually evolving, with many preliminary findings. Studies on the effects of systemic absorption of organic filters in humans are forthcoming; importantly, there has been no evidence of harm over decades of use. Organic (less so inorganic) filters caused coral bleaching in controlled environments, but filter concentrations may not have been realistic, and bleaching is predominantly driven by other factors. No present evidence suggests any marketed sunscreens should be avoided. For consumers with concerns, inorganic ZnO and TiO2 are supported by the most reassuring data at the time of writing.

Acetylene is identified as a key intermediate in methane dehydroaromatization (DHA) reactions present in concentrations O (1) Pascal. The rank of acetylene and other C2 hydrocarbon intermediates is determined by conversion-selectivity profiles collected from 0.01% to 8% methane conversion varied by extent of “non-selective” deactivation of Mo/H-ZSM-5 catalysts. Ethane is shown to be the sole primary product of methane pyrolysis and is sequentially dehydrogenated to ethylene and acetylene – which aromatizes to benzene with rates similar to direct acetylene aromatization measured in the absence of methane. The influence of C H cleavage and C C coupling events to control the rate and reversibility of DHA is assessed by the degree of reversibility control, introduced here for the first time, and the degree of rate control. The approach to equilibrium of the methane to benzene synthesis reaction is length averaged and affinity averaged by the degree of reversibility control of each intervening elementary step to rigorously calculate forward rates of benzene synthesis by use of De Donder relations. Forward rates are found to be invariant along the catalyst bed once the DHA network reaches a pseudo-steady state and methane, ethane, and ethylene form an equilibrated pool.

A contrast agent (CA) in magnetic resonance imaging (MRI) is now an essential add-on to obtain high-quality contrast-enhanced anatomical images for disease diagnosis and monitoring the treatment response. However, the rapid elimination of CAs by the immune system and excretion by the renal route has limited its application. As a result, the CA dose for effective contrast is ever-increasing, resulting in toxic side effects such as gadolinium (Gd) related nephrogenic systemic fibrosis (NSF) toxicity. Considering the widespread application of Gd-based CAs, it is now very important to revisit their formulation in order to improve their local concentration and minimize their dose while achieving clinical goals. Therefore, we have adapted a unique strategy to maximize Gd delivery to the target site using macrophage cell-derived extracellular vesicles (EVs) reconstructed with a Gd-conjugated liposomal system herein called gadolinium infused hybrid EVs (Gd-HEVs). We hypothesize that Gd-HEVs, owing to the presence of immune cell-derived EV protein cargo, can effectively disguise themselves as a biological entity, prolong the retention time for contrast enhancement, and show tumor specificity. Incorporation of Gd into nanoformulations can enhance the longitudinal relaxivity r1 by reducing the tumbling rate of paramagnetic metal complexes. Here, Gd-HEVs showed a higher r1 relaxivity of 9.86 mM−1 s−1 compared to 3.98 mM−1 s−1 of Magnevist® at an equivalent Gd concentration, when measured by clinical 3T MRI. This will allow us to reduce the clinically used Gd concentration about three-fold while maintaining contrast in the clinical window thereby supporting our hypothesis. Furthermore, Gd-HEVs showed a preferential cellular interaction and accumulation towards cancer cells compared to non-cancer cells, both in vitro and in vivo. More importantly, Gd-HEVs showed excellent contrast enhancement in the blood vasculature with a higher retention time compared to its counterpart, Magnevist®. Our study successfully showed that the incorporation of Gd in the EV framework can help to enhance the contrast ability, and therefore it can be a platform technology for the development of safer MRI contrast agents.

In the development of crystal engineering and supramolecular chemistry, cocrystallization has been used as a way to develop novel explosives with tailored properties. We present a novel cocrystal s...

Reported in this contribution are the syntheses of mono-alkynyl complexes [Co(cyclam)( gem- DEE-Ar)Cl]Cl (cyclam = 1,4,8,11-tetraazacycloctetradecane; gem- DEE = geminal -diethynylethene) with Ar as either –C 6 H 4 -4-NO 2 ( 1 ) or –C 6 H 4 -4-NMe 2 ( 2 ) from the reactions between [Co(cyclam)Cl 2 ]Cl and H- gem- DEE-Ar under weak base conditions. Further reaction between compound 1 and Li- gem- DEE–C 6 H 4 –4-NMe 2 at −78 °C afforded the unsymmetric complex trans- [Co(cyclam)( gem- DEE–C 6 H 4 –4-NO 2 )( gem- DEE–C 6 H 4 –4-NMe 2 )]Cl ( 3 ). Providing structural features observed for other Co(cyclam) alkynyls, X-ray diffraction study also reveals the influence of the aryl substituent on the first coordination sphere of the Co(III) center. The presence of an aryl substituent also shifts the Co-based redox couples, and enables intense LMCT transitions that are absent in complexes of unsubstituted gem- DEE. These contrasts can be rationalized based on DFT calculations.

The reaction between [Ni(HMD)](OTf)2 (HMD = 5,7,7,12,14,14-hexamethyl-1,4,8,11-teraazacyclotetradeca-4,11-diene) and benzaldehyde in the presence of NaOH afforded the 5,7-di(styrenyl) derivative [Ni(HMD-Styr)](OTf)2 (1), which was converted to the corresponding cyclam complex [Ni(HMC-Styr)](OTf)2 (2) upon NaBH4 reduction. Addition of NaBPh4 to the reduction reaction mixture led to the isolation of [Ni(HMC-Styr)](BPh4)2 (2′). Single crystal X-ray diffraction studies of 1 and 2′ revealed a square planar NiII center in both [1]2+ and [2]2+, which is characteristic of a low spin NiII d8 center. Complexes 1 and 2 remain low spin in acetonitrile solution as evidenced by their 1H NMR spectra and Vis absorption spectra. Complex 1 displayed two irreversible one-electron reductions between −1.4 and −1.8 V (versus Fc(+1/0)) under Ar in 20% aqueous acetonitrile, and exhibited a new peak around −1.9 V under CO2, indicating a mild activity towards CO2 reduction. In contrast, complex 2 displayed a reversible one-electron reduction at −1.59 V (versus Fc(+1/0)) under Ar, and a less reversible reduction under CO2 without shift in potential, revealing the lack of activity towards CO2.

We demonstrate a novel method to prepare high-quality and uniform nitrogen-doped, three-dimensional, graphene networks through combustion of graphene oxide (GO)–nitrocellulose composites. The N-doped 3D graphene networks have tunable porous morphology and the pore size can be controlled by adjusting the concentration of GO in the nitrocellulose matrix. This new method is a simple method to obtain nitrogen-doped graphene networks and has potential applications in energy storage and conversion, catalysis, and sensors.

Iron is released following electrochemical reduction of immobilized ferritin. In this work, voltammetry is used to elucidate the identity of the released iron. Ferritin was covalently immob...

Two experiments evaluated the effect of implant number, type, and total steroidal dose on live animal performance and carcass traits in heifers fed for three different days on feed (DOF). In experiment 1, heifers (n = 3,780; 70 heifers/pen and 9 pens/treatment; initial body weight [BW] = 309 kg) were used in a 2 × 3 factorial arrangement of treatments. Factors were as follows: 1) implant (all from Merck Animal Health, De Soto, KS): 200 mg trenbolone acetate (TBA) and 20 mg estradiol-17β (E2) administered on arrival (SINGLE), or 80 mg TBA and 8 mg E2 administered on arrival followed by 200 mg TBA and 20 mg E2 after approximately 90 d (REPEATED) and 2) duration of DOF: harvested after approximately 172, 193, and 214. In experiment 2, heifers (n = 3,719; 65 to 70 heifers/pen and 9 pens/treatment; initial BW = 337 kg) were used with the same factors as experiment 1, except DOF were 150, 171, and 192. No implant × DOF interaction (P ≥ 0.06) was noted for any performance parameters in either experiment. Heifers administered REPEATED had improved (P ≤ 0.05) live gain to feed ratio (G:F) and carcass-adjusted G:F and tended (P = 0.09) to have greater hot carcass weight (HCW) in experiment 1. Increasing DOF resulted in greater (P ≤ 0.01) live and carcass-adjusted final BW and decreased (P = 0.01) live ADG in experiment 1. As DOF increased, HCW, HCW gain, and dressing% (P ≤ 0.01) increased in experiment 1. The mean carcass transfer was 79.6% across the 42 d terminal window in experiment 1. In experiment 2, REPEATED had improved (P = 0.03) carcass-adjusted G:F compared with SINGLE, but HCW was not different (P = 0.36) between treatments. Increased DOF resulted in greater (P ≤ 0.01) final live and carcass-adjusted BW, decreased (P ≤ 0.01) live and carcass-adjusted ADG, and poorer (P ≤ 0.01) live and carcass-adjusted G:F in experiment 2. In experiment 2, dressing percentage was greater (P = 0.02) in REPEATED compared with SINGLE. Heifers given SINGLE had greater (P = 0.01) back fat and estimated empty body fat (EBF), whereas REPEATED had fewer (P = 0.01) Yield Grade 4 carcasses and greater (P = 0.01) longissimus muscle (LM) area. Increased DOF resulted in greater (P ≤ 0.04) HCW, HCW gain, dressing%, back fat, LM area, marbling, EBF%, and United States Department of Agriculture (USDA) Prime-grading carcasses, Yield Grade 4 and 5, and over 454-kg carcasses in experiment 2. Carcass ADG and carcass transfer indicate a 0.70 kg carcass ADG between 150 and 192 DOF, resulting in an average carcass transfer of 72.2% in experiment 2. Although feedlot growth performance and HCW did not differ between the implant regimens tested, increasing DOF resulted in decreased live growth performance while increasing the proportion of USDA prime carcasses and HCW.

With evolutionary drug resistance impacting efforts to treat disease, the need for small molecules that exhibit novel molecular mechanisms of action is paramount. In this study, we combined scaffold-directed synthesis with a hybrid experimental and transcriptome analysis to identify bis-spirooxindole cyclopropanes that inhibit cancer cell proliferation through disruption of ribosomal function. These findings demonstrate the value of an integrated, biologically inspired synthesis and assay strategy for the accelerated identification of first-in-class cancer therapeutic candidates.

Glioblastoma multiforme (GBM) is an aggressive primary brain tumor, with poor prognosis. Major obstacles hampering effective therapeutic response in GBM are tumor heterogeneity, high infiltration of immunosuppressive myeloid cells, and the presence of the blood-brain barrier. The C-X-C Motif Chemokine Ligand 12/ C-X-C Motif Chemokine Receptor 4 (CXCL12/ CXCR4) signaling pathway is implicated in GBM invasion and cell cycle progression. While the CXCR4 antagonists (AMD3100) has a potential anti-GBM effects, its poor pharmacokinetic and systemic toxicity had precluded its clinical application. Moreover, the role of CXCL12/ CXCR4 signaling pathway in anti-GBM immunity, particularly in GBM-mediated immunosuppression has not been elucidated. Here, we developed a synthetic protein nanoparticle (SPNPs) coated with the cell-penetrating peptide iRGD (AMD3100 SPNPs) to target the CXCR4/CXCL12 signaling axis in GBM. We showed that AMD3100 SPNPs effectively blocked CXCR4 signaling in mouse and human GBM cells in vitro as well as in GBM model in vivo. This results in inhibition of GBM proliferation and induction of immunogenic tumor cell death (ICD) leading to inhibition of GBM progression. Our data also demonstrate that blocking CXCR4 sensitizes GBM cells to radiation, eliciting enhanced release of ICD ligands. Combining AMD3100 SPNPs with radiotherapy inhibited GBM progression and led to long-term survival; with 60% of mice remaining tumor-free. This was accompanied by an anti-GBM immune response and sustained immunological memory that prevented tumor recurrence without further treatment. Finally, we showed that systemic delivery of AMD3100 SPNPs decreased the infiltration of CXCR4+ monocytic myeloid-derived suppressor cells to the tumor microenvironment. With the potent ICD induction and reprogrammed immune microenvironment, this strategy has significant potential for future clinical translation.Graphical abstractImmunological mechanism targeting Glioblastoma (GBM) upon blocking CXCR4 signaling pathway with AMD3100-conjugated nanoparticles (SPNPs).(1) Radiotherapy induces glioma cell death, followed by Damage-associated molecular patterns (DAMPs) release. Dendritic cells (DC) are activated by DAMPs and migrate to the regional lymph node where they prime cytotoxic T lymphocyte immune response. Tumor-specific cytotoxic T cells infiltrate the tumor and attack glioma cells. (2) Glioma cells express CXCR4, as well its ligand CXCL12. CXCL12 induces glioma cell proliferation and, (3) as well as mobilization in the bone marrow of CXCR4 expressing myeloid MDSC, which will infiltrate the tumor, and inhibit tumor-specific cytotoxic T cells activity. GEMM of glioma when treated systemically with SPNPs AMD3100 SPNPs plus radiation, nanoparticles block the interaction between CXCR4 and CXCL12, thus (4) inhibiting glioma cell proliferation and (5) reducing mobilization in the bone marrow of CXCR4 expressing myeloid MDSC, (6) generating a reduced MDSC tumor infiltration, as well as releasing MDSC inhibition over tumor specific cytotoxic T cell response.

Cadherins are a superfamily of adhesion proteins involved in a variety of biological processes that include the formation of intercellular contacts, the maintenance of tissue integrity, and the development of neuronal circuits. These transmembrane proteins are characterized by ectodomains composed of a variable number of extracellular cadherin (EC) repeats that are similar but not identical in sequence and fold. E-cadherin, along with desmoglein and desmocollin proteins, are three classical-type cadherins that have slightly curved ectodomains and engage in homophilic and heterophilic interactions through an exchange of conserved tryptophan residues in their N-terminal EC1 repeat. In contrast, clustered protocadherins are straighter than classical cadherins and interact through an antiparallel homophilic binding interface that involves overlapped EC1 to EC4 repeats. Here we present molecular dynamics simulations that model the adhesive domains of these cadherins using available crystal structures, with systems encompassing up to 2.8 million atoms. Simulations of complete classical cadherin ectodomain dimers predict a two-phased elastic response to force in which these complexes first softly unbend and then stiffen to unbind without unfolding. Simulated α, β, and γ clustered protocadherin homodimers lack a two-phased elastic response, are brittle and stiffer than classical cadherins, and exhibit complex unbinding pathways that in some cases involve transient intermediates. We propose that these distinct mechanical responses are important for function, with classical cadherin ectodomains acting as molecular shock absorbers and with stiffer clustered protocadherin ectodomains facilitating overlap that favors binding specificity over mechanical resilience. Overall, our simulations provide insights into the molecular mechanics of single cadherin dimers relevant in the formation of cellular junctions essential for tissue function.Statement of SignificanceMulticellular organisms rely on cellular adhesion to survive, and this adhesion is mediated by diverse sets of proteins that include cadherins responsible for organ assembly and tissue integrity maintenance. As parts of cell-cell junctions in epithelial and cardiac tissues, classical cadherins experience forces and must be mechanically robust. In contrast, clustered protocadherins are responsible for neuronal connectivity and are exposed to more subtle mechanical stimuli. We used simulations to study the mechanics of isolated cadherin complexes and found that classical cadherins exhibit a two-phased elastic response that might prevent loss of adhesion during mild mechanical stress. Conversely, we predict that clustered protocadherin complexes are brittle. Our results suggest that each set of cadherins has evolved to adopt distinct mechanical properties.

By visualizing the movements of Rituximab during Antibody dependent cellular phagocytosis (ADCP) of B lymphoma cells by macrophages, we found that Fcγ receptors (FcγR) on the macrophage surface microcluster, recruit Syk and undergro large-scale reorganization at the phagocytic synapse prior to and during engulfment of the target cell. Given these dramatic rearrangements, we analyzed how the surface mobility of Rituximab contributes to FcγR signal amplification and ADCP efficiency. Depolymerization of the target cell actin cytoskeleton resulted in free diffusion of Rituximab docked to CD20, enhanced microcluster reorganization, Syk recruitment and ADCP. Conversely, immobilization of Rituximab by chemical fixation impaired microcluster formation and diminished Syk recruitment and ADCP. In macrophages lacking Syk, Rituximab accumulated at the base of the phagosome and were trogocytosed, consistent with Syk kinase activity being necessary to trigger redistribution of Rituximab-FcγR during engulfment and to prevent antigenic modulation of the target. Total internal reflection fluorescence analysis of FcγR-IgG on fluid supported lipid bilayers revealed a membrane topography displaying inward reaching leading edges and protruding contact sites reminiscent of podosomes. This topography was distinct from the closely apposed macrophage/target membranes observed during engagement of IgG displayed on immobile supported lipid bilayers. The organization of this contact, pseudopod extension and the rearrangement of microclusters depended critically on Arp 2/3. Thus, Syk and Arp2/3 coordinate actin rearrangements and FcγR-IgG complexes that were of previously unrecognized complexity for the clearance of cells displaying surface-mobile antigens.Significance StatementADCP is an important effector mechanism for the removal of malignant, immunologically aberrant, and infected cells during treatment with therapeutic antibodies or adaptive immune responses. Most transmembrane protein antigens are mobile with transient confinement from the actin of the target cell. This work demonstrates that macrophage forces overcome these confinements to rearrange FcγR-IgG-antigen complexes before and during ADCP. Thus, new paradigms are needed as ADCP has largely been studied using model target particles that display immobile antigens. Moreover, we found that the mobility of the therapeutic antibody, Rituximab, on the surface of B lymphoma cells foretells ADCP efficacy, with lower densities of IgG mediating ADCP on increasingly mobile antigens.

Background: Common genetic variation in the arsenic methyltransferase (AS3MT) gene region is known to be associated with arsenic metabolism efficiency (AME), measured as the percentage of dimethylarsinic acid (DMA%) in the urine. Rare, protein-altering variants in AS3MT could have even larger effects on AME, but their contribution to AME has not been investigated. Objectives: We estimated the impact of rare, protein-coding variation in AS3MT on AME using a multi-population approach to facilitate the discovery of population-specific and shared causal rare variants. Methods: We generated targeted DNA sequencing data for the coding regions of AS3MT for three arsenic-exposed cohorts with existing data on arsenic species measured in urine: Health Effects of Arsenic Longitudinal Study (HEALS, n=2,434), Strong Heart Study (SHS, n=868), and New Hampshire Skin Cancer Study (NHSCS, n=666). We assessed the collective effects of rare (allele frequency

Deregulation of dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A) plays a significant role in developmental brain defects, early-onset neurodegeneration, neuronal cell loss, and dementia. Herein, we report the discovery of three new classes of N-heterocyclic DYRK1A inhibitors based on the potent, yet toxic kinase inhibitors, harmine and harmol. An initial in vitro evaluation of the small molecule collection assembled revealed that the core heterocyclic motifs benzofuranones, oxindoles, and pyrrolones, showed statistically significant DYRK1A inhibition. Further, the utilization of a low cost, high-throughput functional genomic in vivo model system to identify small molecule inhibitors that normalize DYRK1A overexpression phenotypes is described. This in vivo assay confirmed the in vitro results, and the resulting correspondence validates generated classes as architectural motifs that serve as potential DYRK1A inhibitors. Further expansion and analysis of these core compound structures will allow discovery of safe, more effective chemical inhibitors of DYRK1A to ameliorate phenotypes caused by DYRK1A overexpression.

Epidermal growth factor receptor (EGFR) activity is necessary and sufficient for corneal epithelial homeostasis. However, the addition of exogenous Epidermal Growth Factor (EGF) does not reliably restore the corneal epithelium when wounded. This is likely due to high levels of endogenous EGF in tear fluid as well as desensitization of the EGFR following ligand stimulation. We hypothesize that preventing receptor downregulation is an alternative mechanism to enhance EGFR signaling and promote the restoration of compromised corneas. Ligand‐dependent EGFR ubiquitylation is associated with the targeted degradation of the receptor. In this manuscript, we determine whether knockout of c‐Cbl, an E3 ubiquitin ligase that ubiquitylates the EGFR, is sufficient to prolong EGFR phosphorylation and sustain signaling. Using CRISPR/Cas9 gene editing, we generated immortalized human corneal epithelial (hTCEpi) cells lacking c‐Cbl. Knockout (KO) cells expressed the other E3 ligases at the same levels as the control cells, indicating other E3 ligases were not up‐regulated. As compared to the control cells, EGF‐stimulated EGFR ubiquitylation was reduced in KO cells, but not completely abolished. Similarly, EGF:EGFR trafficking was slowed, with a 35% decrease in the rate of endocytosis and a twofold increase in the receptor half‐life. This resulted in a twofold increase in the magnitude of EGFR phosphorylation, with no change in duration. Conversely, Mitogen Activating Protein Kinase (MAPK) phosphorylation did not increase in magnitude but was sustained for 2–3 h as compared to control cells. We propose antagonizing c‐Cbl will partially alter receptor ubiquitylation and endocytic trafficking but this is sufficient to enhance downstream signaling., Knockout of c‐Cbl slows EGFR endocytosis and enhances EGFR recycling