Non-neutralizing SARS-CoV-2 N-terminal domain antibodies protect mice against severe disease using Fc-mediated effector functions.

Antibodies perform both neutralizing and non-neutralizing effector functions that protect against certain pathogen-induced diseases. A human antibody directed at the SARS-CoV-2 Spike N-terminal domain (NTD), DH1052, was recently shown to be non-neutralizing yet it protected mice and cynomolgus macaques from severe disease. The mechanisms of this non-neutralizing antibody-mediated protection are unknown. Here we show that Fc effector functions mediate non-neutralizing antibody (non-nAb) protection against SARS-CoV-2 MA10 viral challenge in mice. Though non-nAb infusion did not suppress infectious viral titers in the lung as potently as NTD neutralizing antibody (nAb) infusion, disease markers including gross lung discoloration were similar in nAb and non-nAb groups. Fc functional knockout substitutions abolished non-nAb protection and increased viral titers in the nAb group. Finally, Fc enhancement increased non-nAb protection relative to WT, supporting a positive association between Fc functionality and degree of protection in SARS-CoV-2 infection. This study demonstrates that non-nAbs can utilize Fc-mediated mechanisms to lower viral load and prevent lung damage due to coronavirus infection.

Miniprep assisted proteomics (MAP) for rapid proteomics sample preparation.

Complete enzymatic digestion of proteins for bottom-up proteomics is substantially improved by use of detergents for denaturation and solubilization. Detergents however, are incompatible with many proteases and highly detrimental to LC-MS/MS. Recently; filter-based methods have seen wide use due to their capacity to remove detergents and harmful reagents prior to digestion and mass spectrometric analysis. We hypothesized that non-specific protein binding to negatively charged silica-based filters would be enhanced by addition of lyotropic salts, similar to DNA purification. We sought to exploit these interactions and investigate if low-cost DNA purification spin-filters, 'Minipreps,' efficiently and reproducibly bind proteins for digestion and LC-MS/MS analysis. We propose a new method, Miniprep Assisted Proteomics (MAP), for sample preparation. We demonstrate binding capacity, performance, recovery and identification rates for proteins and whole-cell lysates using MAP. MAP recovered equivalent or greater protein yields from 0.5-50 µg analyses benchmarked against commercial trapping preparations. Nano UHPLC-MS/MS proteome profiling of lysates of Escherichia coli had 99.3% overlap vs. existing approaches and reproducibility of replicate minipreps was 98.8% at the 1% FDR protein level. Label Free Quantitative proteomics was performed and 91.2% of quantified proteins had a %CV <20% (2044/2241). Miniprep Assisted Proteomics can be performed in minutes, shows low variability, high recovery and proteome depth. This suggests a significant role for adventitious binding in developing new proteomics sample preparation techniques. MAP represents an efficient, ultra-low-cost alternative for sample preparation in a commercially obtainable device that costs ∼$0.50 (USD) per miniprep.

The morphological and anatomical variability of the stems of an industrial hemp collection and the properties of its fibres.

Industrial hemp (Cannabis sativa L.) is identified as a leading fibre crop and there is increasing interest in C. sativa fibre due to its new range of industrial applications. However, the complexity of hemp germplasm resulted in insufficient information on the effect of genotypes on fibre quality and quantity. In this study, 16 fibre and non-fibre type hemp genotypes were evaluated to compare the morpho-anatomical differences of stems and physico-mechanical fibre properties under three retting methods and to understand the effect of stem colour on the properties of hemp fibres. Morphological markers were scored and stem anatomy was examined using live and herbarium collections. Stems were retted using chemical, enzymatic, and microbiological methods. The resulting fibres were tested for tensile strength, moisture retention, colour, bast and hurd dry weights. Hemp genotypes showed morphological variations that affect fibre processing and a unique pattern of fibre wedges in cross-sections of the basal internode. Fibre yield, tensile strength, colour, and moisture retention significantly varied among the genotypes. The hemp collection used in this study formed three clusters in principal component analysis and traits such as internodal length, node number, hurd yield, and tensile strength highly contributed to the total variability. Additionally, non-fibre type hemp genotypes that showed important fibre properties were identified. The hemp genotypes that were selected based on our approaches can be tailored towards the specificities of the end-usage of choice. Our methods will enable the exploration of hemp genetic diversity pertaining to fibre properties and contribute to the preliminary identification of genotypes as a supplement to genetic analyses.

Antibacterial Electrodeposited Copper-Doped Calcium Phosphate Coatings for Dental Implants.

Dental implants provide a good solution for the replacement of tooth roots. However, the full restoration of tooth functions relies on the bone-healing period before positioning the abutment and the crown on the implant, with the associated risk of post-operative infection. This study aimed at developing a homogeneous and adherent thin calcium phosphate antibacterial coating on titanium dental implants by electrodeposition to favor both implant osseointegration and to limit peri-implantitis. By combining global (XRD, FTIR-ATR, elemental titration) and local (SEM, Raman spectroscopy on the coating surface and thickness) characterization techniques, we determined the effect of electrodeposition time on the characteristics and phases content of the coating and the associated mechanism of its formation. The 1-min-electrodeposited CaP coating (thickness: 2 ± 1 µm) was mainly composed of nano-needles of octacalcium phosphate. We demonstrated its mechanical stability after screwing and unscrewing the dental implant in an artificial jawbone. Then, we showed that we can reach a high copper incorporation rate (up to a 27% Cu/(Cu+Ca) molar ratio) in this CaP coating by using an ionic exchange post-treatment with copper nitrate solution at different concentrations. The biological properties (antibiofilm activity and cytotoxicity) were tested in vitro using a model of mixed bacteria biofilm mimicking peri-implantitis and the EN 10993-5 standard (direct contact), respectively. An efficient copper-doping dose was determined, providing an antibiofilm property to the coating without cytotoxic side effects. By combining the electrodeposition and copper ionic exchange processes, we can develop an antibiofilm calcium phosphate coating on dental implants with a tunable thickness and phases content.

Calcium phosphate coatings elaborated by the soaking process on titanium dental implants: Surface preparation, processing and physical-chemical characterization.

OBJECTIVE: Dental implant manufacturers are looking for new surfaces to improve osseointegration. It is accepted that calcium phosphate coatings favor bone healing. Among all the techniques, the soaking process seems attractive because of its ability in producing a bioactive coating at low temperature. The objective of this study is to improve the titanium implant surface roughness and chemistry by optimizing the surface preparation and the soaking process parameters to produce a bioactive and adherent calcium phosphate coating. METHODS: Titanium samples were sandblasted and acid etched. Coatings were realized by an alternate soaking process including a centrifugation step to create a phosphate solution thin film on the implant that reacts with the calcium of the second bath. We performed a characterization of the sample surface with complementary physical and physico-chemical techniques to assess the effect of surface preparation and coating process operating parameters on coating formation and characteristics. RESULTS: Surface preparation led to a roughness around 1.6µm, micro-porosities, high surface wettability and removed the embedded sandblasting particles. We showed that the centrifugation step is critical and determines the coating formation, coverage and thickness. A thin coating (∼2µm) composed of apatite analogous to bone mineral was deposited. The coating adhesion was demonstrated by screwing/unscrewing test in an artificial jawbone. SIGNIFICANCE: The titanium dental implant pre-treatment and coating developed in this study is expected to favor early implant osseointegration through coating dissolution in vivo and could be associated with biological active agents to confer additional functionality to the coating.

Efficacy and Cost of Awake Thoracoscopy and Video-Assisted Thoracoscopic Surgery in the Undiagnosed Pleural Effusion.

BACKGROUND: The study aim is to compare the diagnostic yield, safety, and cost of outpatient awake thoracoscopy (AT) with video-assisted thoracoscopic surgery (VATS) pleural biopsy in undiagnosed pleural effusions. METHODS: The diagnostic yield of pleural biopsy performed by AT or VATS in patients with undiagnosed exudative pleural effusions at a tertiary thoracic surgery center in Canada between 2011 and 2015 was retrospectively evaluated. Test sensitivity, specificity, positive predictive value, and negative predictive value were compared. Procedure safety, hospital length of stay, additional pleural-based interventions, and procedure-related costs were compared. RESULTS: Patients underwent either AT (n = 78) or VATS (n = 99) during the study period. Sensitivity, specificity, positive predictive value, and negative predictive value were 85%, 100%, 100%, and 79% for AT and 93%, 94%, 99%, and 76% for VATS, with no significant difference in diagnostic test performance. There was no difference in the rate of major complications (2 AT [2.6%] versus 4 VATS [4.0%], p = 0.696), minor complications (14 AT [17.9%] versus 16 VATS [16.2%], p = 0.841) or need for additional pleural-based procedures (20 AT [25.6%] versus 18 VATS [18.2%], p = 0.270). The VATS was associated with longer median hospital stay (VATS 3 days [interquartile range: 1 to 4] versus AT 0 days [interquartile range: 0 to 1], z = 6.98, p < 0.001) and a higher procedure-related average cost (VATS Canadian dollars $7,962 [95% confidence interval: $7,134 to $8,790] versus AT Canadian dollars $2,815 [95% confidence interval: $2,010 to $3,620], p < 0.001). CONCLUSIONS: Awake thoracoscopy and VATS have similar diagnostic yield and safety profiles in the assessment of undiagnosed pleural effusions; however, AT is associated with shorter length of stay and lower average per-procedure cost. In the appropriate clinical setting, AT may be the diagnostic test of choice.

Plasmon-Induced Conductance Switching of an Electroactive Conjugated Polymer Nanojunction.

A plasmonic molecular electronic device, consisting of poly(3,4-ethylenedioxythiophene) (PEDOT) nanowires bridging an ultramicroelectrode and an indium tin oxide (ITO) substrate covered by gold nanoparticles (Au NPs), has been developed. Light irradiation of this device has a dramatic impact on its conductance. Polymer strands, maintained electrochemically in their oxidized, conducting state, reversibly switch to their insulating state upon irradiation by visible-wavelength light, resulting in a sharp decrease in the conductance. The high-conductance state is restored when the light is turned off. Switching depends on the wavelength and the intensity of the incident light. It is due to reversible reduction of the nanosized region of PEDOT nanowires in contact with a gold NP and is attributed to plasmon-induced hot-electron injection into the PEDOT. The high/low conductance ratio can be as great as 1000, and switching requires low light intensity (220 W/m2). These results could open the way to the design of a new family of optoelectronic switches.

Tailored Surfaces/Assemblies for Molecular Plasmonics and Plasmonic Molecular Electronics.

Molecular plasmonics uses and explores molecule-plasmon interactions on metal nanostructures for spectroscopic, nanophotonic, and nanoelectronic devices. This review focuses on tailored surfaces/assemblies for molecular plasmonics and describes active molecular plasmonic devices in which functional molecules and polymers change their structural, electrical, and/or optical properties in response to external stimuli and that can dynamically tune the plasmonic properties. We also explore an emerging research field combining molecular plasmonics and molecular electronics.

Micro/nano-structured polypyrrole surfaces on oxidizable metals as smart electroswitchable coatings.

Polypyrrole (PPy) films were electrodeposited from a pyrrole/sodium salicylate solution in water, through two-dimensional (2-D) polystyrene (PS) templates self-assembled on various oxidizable metals, after which the template was removed by dissolution in tetrahydrofuran (THF). The resulting PPy films were analyzed by scanning electron microscopy and atomic force microscopy. Two-dimensional PPy honeycomb structures are obtained on copper or mild steel by using PS spheres of various sizes. The morphology of these structures was controlled electrochemically, as an increase in the polymerization charge does not disturb the PPy honeycomb arrangement, leading instead to the formation of deeper pores accompanied by a change in their diameter. The hydrophobicity of the reduced micro-structured PPy surface is much greater than that of a bulk PPy film generated on the same metal. Reversible electro-switching of the wettability was obtained with marked variation of the apparent contact angle upon PPy oxido-reduction, and an important effect of film micro-structuration upon the wettability range.

Host-guest complexation: a convenient route for the electroreduction of diazonium salts in aqueous media and the formation of composite materials.

Electrochemical grafting of a water-insoluble diazonium salt in aqueous media onto an electrode surface was achieved by host-guest complexation. 1-(2-Bisthienyl)-4-aminobenzene (BTAB) was solubilized in a water/beta-cyclodextrin solution (beta-CD). The corresponding diazonium salt was generated in situ then electroreduced. This process leads to the attachment of bithiophene or short oligothiophene groups to the electrode surface. The modified surfaces were analyzed by cyclic voltammetry (CV), scanning electrochemical microscopy (SECM), X-ray photoelectron spectroscopy (XPS), infrared reflection absorption spectroscopy (IRRAS), and atomic force microscopy (AFM). The electrochemical investigations show that the water-based modified surface is similar to one generated in acetonitrile without beta-CD. Thus, the attached organic layer behaves like an electrochemical switch (above some threshold potential, a soluble external probe is oxidized, but the oxidized form cannot be reduced). The modified surfaces consist of grafted bisthienylbenzene (BTB) and cyclodextrins that can be removed from the surface. This procedure may be considered as a new means of creating a surface made of submicrometric holes in an organic semiconducting layer.

Spatial frequency characteristics of nearby neurons in cats' visual cortex.

Various methods have allowed mapping of responses to several stimulus features on the cortical surface, particularly edge orientation and motion direction. The cortical mapping of spatial frequencies (SF), which is the basic property that leads to perception of spatial details of visual objects, is still controversial. We recorded simultaneously extracellular action potentials from neighboring cells in superficial layers of the area 17-18 border region of anesthetized cats. Responses of nearby cells to sine-wave gratings of varying SF were analyzed. Spatial frequency tuning curves were cross-correlated to establish the degree of similarity between the curves and optimal SFs were compared for each pair of neurons. The investigation showed that only about a half of nearby neurons exhibited close optimal SFs and similar tuning curves. The results suggest that SF channels do not show a clear clustering within a small pool of neurons. Such organization may contribute to the perception of spatial details at all orientations and motion directions.

Synthesis and characterization of nanoheterostructures based on oligothiophene functionalized Ru nanoparticles.

Monodisperse ruthenium nanoparticles functionalized by electroactive oligothiophenes have been prepared and characterized. Using TEM, UV-visible and FTIR we established that the organization of these nanoparticles into nanospheres can be directly controlled via modulation of the pi-pi interaction between the organic components adsorbed on the surface. This finding also shows that the self-assembled nanoheterostructures may be switched from monodisperse nanoparticles to ordered nanospheres by tuning the pH.