Neuronal NADPH oxidase is required for neurite regeneration of Aplysia bag cell neurons.

NADPH oxidase (Nox), a major source of reactive oxygen species (ROS), is involved in neurodegeneration after injury and disease. Nox is expressed in both neuronal and non-neuronal cells and contributes to an elevated ROS level after injury. Contrary to the well-known damaging effect of Nox-derived ROS in neurodegeneration, recently a physiological role of Nox in nervous system development including neurogenesis, neuronal polarity, and axonal growth has been revealed. Here, we tested a role for neuronal Nox in neurite regeneration following mechanical transection in cultured Aplysia bag cell neurons. Using a novel hydrogen peroxide (H2 O2 )-sensing dye, 5'-(p-borophenyl)-2'-pyridylthiazole pinacol ester (BPPT), we found that H2 O2 levels are elevated in regenerating growth cones following injury. Redistribution of Nox2 and p40phox in the growth cone central domain suggests Nox2 activation after injury. Inhibiting Nox with the pan-Nox inhibitor celastrol reduced neurite regeneration rate. Pharmacological inhibition of Nox is correlated with reduced activation of Src2 tyrosine kinase and F-actin content in the growth cone. Taken together, these findings suggest that Nox-derived ROS regulate neurite regeneration following injury through Src2-mediated regulation of actin organization in Aplysia growth cones.

Copper(I)-Pyrazolate Complexes as Solid-State Phosphors: Deep-Blue Emission through a Remote Steric Effect.

We describe a novel manifestation of rigidochromic behavior in a series of tetranuclear Cu(I)-pyrazolate (Cu4pz4) macrocycles, with implications for solid-state luminescence at deep-blue wavelengths (<460 nm). The Cu4pz4 emissions are remarkably sensitive to structural effects far from the luminescent core: when 3,5-di-tert-butylpyrazoles are used as bridging ligands, adding a C4 substituent can induce a blue shift of more than 100 nm. X-ray crystal and computational analyses reveal that C4 units influence the conformational behavior of adjacent tert-butyl groups, with a subsequent impact on the global conformation of the Cu4pz4 complex. Emissions are mediated primarily through a cluster-centered triplet (3CC) state; compression of the Cu4 cluster into a nearly close-packed geometry prevents the reorganization of its excited-state structure and preserves the 3CC energy at a high level. The remote steric effect may thus offer alternative strategies toward the design of phosphors with rigid excited-state geometries.

Clinical and genomic correlates of imatinib response in melanomas with KIT alterations.

BACKGROUND: Imatinib is an active agent for some patients with melanoma harbouring c-KIT alterations. However, the genetic and clinical features that correlate with imatinib sensitivity are not well-defined. METHODS: We retrospectively evaluated 38 KIT-altered melanoma patients from five medical centres who received imatinib, and pooled data from prospective studies of imatinib in 92 KIT-altered melanoma patients. Baseline patient and disease characteristics, and clinical outcomes were assessed. RESULTS: In the pooled analysis (N = 130), alterations in exons 11/13 had the highest response rates (38% and 33%); L576P (N = 23) and K642E (N = 12) mutations had ORR of 52% and 42%, respectively. ORR was 38% (mucosal), 25% (acral), and 8% (unknown-primary). PFS appeared longer in exon 11/13 vs. exon 17 alterations (median 4.3 and 4.5 vs. 1.1 months; p = 0.19), with similar superiority in OS (median 19.7 and 15.4 vs. 12.1 months; p = 0.20). By histology, median PFS was 4.5 months (mucosal), 2.7 (acral), and 5.0 (unknown-primary) [p = 0.36]. Median OS was 18.0 months (mucosal), 21.8 (acral), 11.5 (unknown-primary) [p = 0.26]. In multivariate analyses, mucosal melanoma was associated with higher PFS and exon 17 mutations were associated with reduced PFS. CONCLUSION: This multicenter study highlights KIT-alterations sensitive to imatinib and augments evidence for imatinib in subsets of KIT-altered melanoma.

Radiation-Tolerant Thin-Film Electrodes for pH Monitoring in Sterile Media.

Thin-film pH electrodes on thermoplastic substrates can be subjected to γ-radiation (up to 45 kGy) without loss of stability or sensing performance, with important ramifications for monitoring analytes in sterile environments. pH-sensing membranes composed of polyvinyl chloride (PVC), trioctyl trimellitate (TOTM), and a standard hydrogen ionophore were cast onto screen-printed carbon electrodes with exfoliated graphene as a solid contact. Irradiated thin-film electrodes were conditioned in phosphate buffers and monitored for up to 3 months for changes in voltage readout and pH sensitivity, relative to untreated controls. The sensitivities of both irradiated and control electrodes were consistently Nernstian over a 100 day window, with both types exhibiting logarithmic voltage decays but in opposite directions. The γ-irradiated electrodes had excellent long-term stability with quasi-linear voltage drifts of +0.28 mV (∼0.005 pH) per day. Voltage readouts from sterilized thin-film electrodes in cell culture media could be converted by single-point calibration into pH values that fell within 0.07 units relative to a commercial pH meter (calibrated daily).

Chiroptical Transitions of Enantiomeric Ligand-Activated Nickel Oxides.

Ligand-induced chirality in transition-metal oxide (TMO) nanostructures have great potential for designing materials with tunable chiroptical effects. Herein, a facile strategy is reported to prepare chiroptical active nickel-oxide hybrids combined with pH adjustment, and the redox treatment results in ligand transformation, which is attributable to multiple optical transitions in the TMO nanostructures. The theoretical calculation also explains the chiral origins based on their complex models based on empirical analysis. It is also shown that enantiomeric TMO nanoparticles can be used as chiral inducers for chiroptical sensitive polymerization. These results demonstrate that TMO nanostructures can provide rational control over photochemical synthesis and chiral transfer of inorganics nanoarchitecture chirality.

siRNA Delivery Using Dithiocarbamate-Anchored Oligonucleotides on Gold Nanorods.

We present a robust method for loading small interfering RNA (siRNA) duplexes onto the surfaces of gold nanorods (GNRs) at high density, using near-infrared laser irradiation to trigger their intracellular release with subsequent knockdown activity. Citrate-stabilized GNRs were first coated with oleylsulfobetaine, a zwitterionic amphiphile with low cytotoxicity, which produced stable dispersions at high ionic strength. Amine-modified siRNA duplexes were converted into dithiocarbamate (DTC) ligands and adsorbed onto GNR surfaces in a single incubation step at 0.5 M NaCl, simplifying the charge screening process. The DTC anchors were effective at minimizing premature siRNA desorption and release, a common but often overlooked problem in the use of gold nanoparticles as oligonucleotide carriers. The activity of GNR-siRNA complexes was evaluated systematically against an eGFP-producing ovarian cancer cell line (SKOV-3) using folate receptor-mediated uptake. Efficient knockdown was achieved by using a femtosecond-pulsed laser source to release DTC-anchored siRNA, with essentially no contributions from spontaneous (dark) RNA desorption. GNRs coated with thiol-anchored siRNA duplexes were less effective and also permitted low levels of knockdown activity without photothermal activation. Optimized siRNA delivery conditions were applied toward the targeted knockdown of transglutaminase 2, whose expression is associated with the progression of recurrent ovarian cancer, with a reduction in activity of >80% achieved after a single pulsed laser treatment.

Eco-friendly (green) synthesis of magnetically active gold nanoclusters.

Au-FexOy composite nanoparticles (NPs) are of great technological interest due to their combined optical and magnetic properties. However, typical syntheses are neither simple nor ecologically friendly, creating a challenging situation for process scale-up. Here we describe conditions for preparing Au-FexOy NPs in aqueous solutions and at ambient temperatures, without resorting to solvents or amphiphilic surfactants with poor sustainability profiles. These magnetic gold nanoclusters (MGNCs) are prepared in practical yields with average sizes slightly below 100 nm, and surface plasmon resonances that extend to near-infrared wavelengths, and sufficient magnetic moment (up to 6 emu g-1) to permit collection within minutes by handheld magnets. The MGNCs also produce significant photoluminescence when excited at 488 nm. Energy dispersive X-ray (EDX) analysis indicates a relatively even distribution of Fe within the MGNCs, as opposed to a central magnetic core.

Label-Free Detection and Discrimination of Bacterial Pathogens Based on Hemin Recognition.

Hemin linked to hexa(ethylene glycol)bishydrazide was patterned by inkjet printing into periodic microarrays, and evaluated for their ability to capture bacterial pathogens expressing various hemin receptors. Bacterial adhesion was imaged under darkfield conditions with Fourier analysis, supporting a label-free method of pathogen detection. Hemin microarrays were screened against a panel of 16 bacteria and found capable of capturing multiple species, some with limits of detection as low as 10(3) cfu/mL. Several Gram-positive strains including Staphylococcus aureus and Bacillus anthracis also exhibited rapid adhesion, enabling pattern recognition within minutes of exposure. This can be attributed to differences in hemin acquisition systems: aggressively adherent bacteria express cell-surface hemin receptors (CSHRs) that enable direct hemin binding and uptake, whereas other types of bacteria including most Gram-negative strains rely on the secretion and recapture of soluble proteins (hemophores) for hemin acquisition, with consequently longer times for ligand binding and detection.

Effect of the Proximal Abducting Ulnar Osteotomy on Intra-Articular Pressure Distribution and Contact Mechanics of Congruent and Incongruent Canine Elbows Ex Vivo.

OBJECTIVE: To determine the effects of the Proximal Abducting Ulnar Osteotomy (PAUL) on contact pressures of congruent and incongruent (short radius) canine elbows. STUDY DESIGN: Ex vivo biomechanical study. SAMPLE POPULATION: Unpaired normal cadaveric canine forelimbs (n=16). METHODS: A servohydraulic testing frame and thin-film sensors were utilized to measure intra-articular contact area (CA), mean contact pressure (mCP), and peak contact pressure (pCP) for medial and lateral elbow compartments. Percent contribution of the medial compartment relative to the whole (%Med) was also examined. Baseline data were collected in 9 congruent elbows and 7 incongruent elbows where the radius was shortened. Both sets of elbows were tested following ulnar osteotomy and sequential placement of 2 and 3 mm PAUL plates and paw repositioning (to account for any medial to lateral shift of transarticular forces). Paired t-tests compared sequential procedural steps. P<.05 was significant. RESULTS: For congruent elbows, the 2 mm PAUL plate decreased CA in both compartments compared to baseline; lateral pCP increased with subsequent paw repositioning. Induction of radio-ulnar incongruity decreased CA and increased mCP medially, decreased pCP laterally, and increased %MedCA and %MedmCP compared to baseline. Both PAUL plates decreased mCP and pCP medially, with no effect laterally. Paw repositioning had no effect. CONCLUSION: The PAUL procedure had no effect on medial compartment pressure in the congruent elbow. It may ameliorate increased medial compartment pressure in the incongruent elbow. This change does not result from a medial to lateral compartmental shift and deserves further investigation.

Time-Resolved Proteomic Visualization of Dendrimer Cellular Entry and Trafficking.

Our understanding of the complex cell entry pathways would greatly benefit from a comprehensive characterization of key proteins involved in this dynamic process. Here we devise a novel proteomic strategy named TITAN (Tracing Internalization and TrAfficking of Nanomaterials) to reveal real-time protein-dendrimer interactions using a systems biology approach. Dendrimers functionalized with photoreactive cross-linkers were internalized by HeLa cells and irradiated at set time intervals, then isolated and subjected to quantitative proteomics. In total, 809 interacting proteins cross-linked with dendrimers were determined by TITAN in a detailed temporal manner during dendrimer internalization, traceable to at least two major endocytic mechanisms, clathrin-mediated and caveolar/raft-mediated endocytosis. The direct involvement of the two pathways was further established by the inhibitory effect of dynasore on dendrimer uptake and changes in temporal profiles of key proteins.

Cys34-PEGylated Human Serum Albumin for Drug Binding and Delivery.

Polyethylene glycol (PEG) derivatives were conjugated onto the Cys-34 residue of human serum albumin (HSA) to determine their effects on the solubilization, permeation, and cytotoxic activity of hydrophobic drugs such as paclitaxel (PTX). PEG(C34)HSA conjugates were prepared on a multigram scale by treating native HSA (n-HSA) with 5- or 20-kDa mPEG-maleimide, resulting in up to 77% conversion of the mono-PEGylated adduct. Nanoparticle tracking analysis of PEG(C34)HSA formulations in phosphate buffer revealed an increase in the number of nanosized aggregates relative to n-HSA, both in the absence and presence of PTX. Cell viability studies conducted with MCF-7 breast cancer cells indicated that PTX cytotoxicity was enhanced by PEG(C34)HSA when mixed at 10:1 mol ratios, up to a 2-fold increase in potency relative to n-HSA. The PEG(C34)HSA conjugates were also evaluated as PTX carriers across monolayers of HUVEC and hCMEC/D3 cells, and found to have permeation profiles nearly identical to those of n-HSA.

Nanometric resolution in the hydrodynamic size analysis of ligand-stabilized gold nanorods.

The stability and hydrodynamic size of ligand-coated gold nanorods (GNRs; aspect ratio 3.6) have been characterized by nanoparticle tracking analysis (NTA)-a single-particle counting method that can measure size distributions with low nanometer resolution. Stable aqueous suspensions of citrate-stabilized GNRs (cit-GNRs) are amenable to surface functionalization without loss of dispersion control. Cit-GNRs can be treated with chemisorptive ligands (thiols and dithiocarbamates), nonionic surfactants (Tween 20), and proteins (human serum albumin), all of which produce stable suspensions at low surfactant concentrations. The precision of NTA (relative standard deviation 10-12%, standard error <2%) is sufficient to allow differences in the hydrodynamic size of coated GNRs to be interpreted in terms of surfactant structure and conformation.

Citrate-stabilized gold nanorods.

Stable aqueous dispersions of citrate-stabilized gold nanorods (cit-GNRs) have been prepared in scalable fashion by surfactant exchange from cetyltrimethylammonium bromide (CTAB)-stabilized GNRs, using polystyrenesulfonate (PSS) as a detergent. The surfactant exchange process was monitored by infrared spectroscopy, surface-enhanced Raman scattering (SERS), and X-ray photoelectron spectroscopy (XPS). The latter established the quantitative displacement of CTAB (by PSS) and of PSS (by citrate). The Cit-GNRs are indefinitely stable at low ionic strength, and are conducive to further ligand exchange without loss of dispersion stability. The reliability of the surface exchange process supports the systematic analysis of ligand structure on the hydrodynamic size of GNRs, as described in a companion paper.

Glycosyl dithiocarbamates: ß-selective couplings without auxiliary groups.

In this article, we evaluate glycosyl dithiocarbamates (DTCs) with unprotected C2 hydroxyls as donors in ß-linked oligosaccharide synthesis. We report a mild, one-pot conversion of glycals into ß-glycosyl DTCs via DMDO oxidation with subsequent ring opening by DTC salts, which can be generated in situ from secondary amines and CS2. Glycosyl DTCs are readily activated with Cu(I) or Cu(II) triflate at low temperatures and are amenable to reiterative synthesis strategies, as demonstrated by the efficient construction of a tri-ß-1,6-linked tetrasaccharide. Glycosyl DTC couplings are highly ß-selective despite the absence of a preexisting C2 auxiliary group. We provide evidence that the directing effect is mediated by the C2 hydroxyl itself via the putative formation of a cis-fused bicyclic intermediate.

Synthesis and reactivity of 4'-deoxypentenosyl disaccharides.

4-Deoxypentenosides (4-DPs) are versatile synthons for rare or higher-order pyranosides, and they provide an entry for structural diversification at the C5 position. Previous studies have shown that 4-DPs undergo stereocontrolled DMDO oxidation; subsequent epoxide ring-openings with various nucleophiles can proceed with both anti or syn selectivity. Here, we report the synthesis of α- and ß-linked 4'-deoxypentenosyl (4'-DP) disaccharides, and we investigate their post-glycosylational C5' additions using the DMDO oxidation/ring-opening sequence. The α-linked 4'-DP disaccharides were synthesized by coupling thiophenyl 4-DP donors with glycosyl acceptors using BSP/Tf2O activation, whereas ß-linked 4'-DP disaccharides were generated by the decarboxylative elimination of glucuronyl disaccharides under microwave conditions. Both α- and ß-linked 4'-DP disaccharides could be epoxidized with high stereoselectivity using DMDO. In some cases, the α-epoxypentenosides could be successfully converted into terminal l-iduronic acids via the syn addition of 2-furylzinc bromide. These studies support a novel approach to oligosaccharide synthesis, in which the stereochemical configuration of the terminal 4'-DP unit is established at a post-glycosylative stage.

Pd- and Ni-catalyzed cross-coupling reactions in the synthesis of organic electronic materials.

Organic molecules and polymers with extended π-conjugation are appealing as advanced electronic materials, and have already found practical applications in thin-film transistors, light emitting diodes, and chemical sensors. Transition metal (TM)-catalyzed cross-coupling methodologies have evolved over the past four decades into one of the most powerful and versatile methods for C-C bond formation, enabling the construction of a diverse and sophisticated range of π-conjugated oligomers and polymers. In this review, we focus our discussion on recent synthetic developments of several important classes of π-conjugated systems using TM-catalyzed cross-coupling reactions, with a perspective on their utility for organic electronic materials.

Base-free trifluoroacetylation: From methyl glucopyranoside to cellulose nanofibers.

Trifluoroacetic anhydride (TFAA) reacts smoothly with low molecular weight carbohydrates and cellulose nanofibers (CNFs) under base-free conditions. Methyl α- and ß-d-glucopyranoside were used as model compounds to optimize reaction conditions, which were then applied to lyophilized CNFs for surface modification. ATR-IR spectroscopy and powder X-ray diffraction were employed to characterize the modified CNFs. Trifluoroacetylation for 4 h yields a degree of substitution (DS) of 0.4 acyl groups per anhydroglucose unit while maintaining a crystallinity index near 50 %. DS values were quantified by gravimetry, acid-base titration after saponification, and a novel approach utilizing solution 19F NMR spectroscopy which offers greater accuracy than the other techniques. This study presents an efficient, base-free method for derivatizing carbohydrates as well as surface functionalization of CNFs with trifluoroacetyl groups, potentially expanding their application in fiber-reinforced thermoplastic composites.

Rigidochromism of tetranuclear Cu(I)-pyrazolate macrocycles: steric crowding with trifluoromethyl groups.

Macrocyclic Cu(I)-pyrazolate tetramers (Cu4pz4) can fold into compact structures with luminescent Cu4 cores whose emission wavelengths are sensitive to steric effects along the periphery of the macrocycle. Introducing CF3 at the C4 position of 3,5-di-tBu-pyrazolate increases steric crowding that modifies the conformational behavior of the Cu4pz4 complex, highlighted by a low-temperature martensitic transition. Variable-temperature analysis of solid-state luminescence reveal an unexpected blueshifting of emission with rising temperature.

Photodynamic treatment of Staphylococcus aureus with non-iron hemin analogs in the presence of hydrogen peroxide.

Bacteria subjected to antiseptic or antibiotic stress often develop tolerance, a trait that can lead to permanent resistance. To determine whether photodynamic agents could be used to counter tolerance, we evaluated three non-iron hemin analogs (M-PpIX; M = Al, Ga, In) as targeted photosensitizers for antimicrobial photodynamic inactivation (aPDI) following exposure to sublethal H2O2. Al-PpIX is an active producer of ROS whereas Ga- and In-PpIX are more efficient at generating singlet oxygen. Al- and Ga-PpIX are highly potent aPDI agents against S. aureus and methicillin-resistant strains (MRSA) with antimicrobial activity (3 log reduction in colony-forming units) at nanomolar concentrations. The aPDI activities of Al- and Ga-PpIX against S. aureus were tested in the presence of 1 mM H2O2 added at different stages of growth. Bacteria exposed to H2O2 during log-phase growth were less susceptible to aPDI but bacteria treated with H2O2 in their postgrowth phase exhibited aPDI hypersensitivity, with no detectable colony growth after treatment with 15 nM Ga-PpIX.

Neoadjuvant immunotherapy in resectable non-small-cell lung cancer.

The advent of immune checkpoint inhibition has pushed the treatment paradigm for resectable non-small-cell lung cancer (NSCLC) toward neoadjuvant therapy. A growing number of promising trials have examined the utility of neoadjuvant immunotherapy, both alone and in combination with other modalities such as radiation therapy (RT) and chemotherapy. The phase II LCMC3 and NEOSTAR trials demonstrated a role for neoadjuvant immunotherapy in inducing meaningful pathologic responses, and another phase II trial established the feasibility of combining neoadjuvant durvalumab with RT. Significant interest in neoadjuvant chemoimmunotherapy resulted in the conduct of multiple successful phase II trials including the Columbia trial, NADIM, SAKK 16/14, and NADIM II. Across these trials, neoadjuvant chemoimmunotherapy led to high rates of pathologic response and improved surgical outcomes without compromising surgical timing or feasibility. CheckMate-816, which was a randomized phase III trial studying neoadjuvant nivolumab in addition to chemotherapy, definitively established a benefit for neoadjuvant chemoimmunotherapy compared to chemotherapy alone for resectable NSCLC. Despite the growing literature and success of these trials, several outstanding questions remain, including the relationship between pathologic response and patient survival, the role of biomarkers such as programmed death ligand 1 and circulating tumor DNA in determining patient selection and treatment course, and the utility of additional adjuvant therapies. Longer follow-up of CheckMate-816 and other ongoing phase III trials may help address these questions. Ultimately, the complexity of managing resectable NSCLC highlights the importance of a multidisciplinary approach to patient care.