SARS-CoV-2 infection of the oral cavity and saliva.

Despite signs of infection-including taste loss, dry mouth and mucosal lesions such as ulcerations, enanthema and macules-the involvement of the oral cavity in coronavirus disease 2019 (COVID-19) is poorly understood. To address this, we generated and analyzed two single-cell RNA sequencing datasets of the human minor salivary glands and gingiva (9 samples, 13,824 cells), identifying 50 cell clusters. Using integrated cell normalization and annotation, we classified 34 unique cell subpopulations between glands and gingiva.

Integrated Single-Cell Atlases Reveal an Oral SARS-CoV-2 Infection and Transmission Axis.

Despite signs of infection, the involvement of the oral cavity in COVID-19 is poorly understood. To address this, single-cell RNA sequencing data-sets were integrated from human minor salivary glands and gingiva to identify 11 epithelial, 7 mesenchymal, and 15 immune cell clusters. Analysis of SARS-CoV-2 viral entry factor expression showed enrichment in epithelia including the ducts and acini of the salivary glands and the suprabasal cells of the mucosae.

Basal expression of interferon regulatory factor 1 drives intrinsic hepatocyte resistance to multiple RNA viruses.

Current models of cell-intrinsic immunity to RNA viruses centre on virus-triggered inducible antiviral responses initiated by RIG-I-like receptors or Toll-like receptors that sense pathogen-associated molecular patterns, and signal downstream through interferon regulatory factors (IRFs), transcription factors that induce synthesis of type I and type III interferons. RNA viruses have evolved sophisticated strategies to disrupt these signalling pathways and evade elimination by cells, attesting to their importance. Less attention has been paid to how IRFs maintain basal levels of protection against viruses.

TIM1 (HAVCR1) Is Not Essential for Cellular Entry of Either Quasi-enveloped or Naked Hepatitis A Virions.

Receptor molecules play key roles in the cellular entry of picornaviruses, and TIM1 (HAVCR1) is widely accepted to be the receptor for hepatitis A virus (HAV), an unusual, hepatotropic human picornavirus. However, its identification as the hepatovirus receptor predated the discovery that hepatoviruses undergo nonlytic release from infected cells as membrane-cloaked, quasi-enveloped HAV (eHAV) virions that enter cells via a pathway distinct from naked, nonenveloped virions. We thus revisited the role of TIM1 in hepatovirus entry, examining both adherence and infection/replication in cells with clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9-engineered TIM1 knockout.

Ecological Risk Assessment of Nano-enabled Pesticides: A Perspective on Problem Formulation.

Plant protection products containing nanomaterials that alter the functionality or risk profile of active ingredients (nano-enabled pesticides) promise many benefits over conventional pesticide products. These benefits may include improved formulation characteristics, easier application, better targeting of pest species, increased efficacy, lower application rates, and enhanced environmental safety. After many years of research and development, nano-enabled pesticides are starting to make their way into the market.

NS5A inhibitors unmask differences in functional replicase complex half-life between different hepatitis C virus strains.

Hepatitis C virus (HCV) RNA is synthesized by the replicase complex (RC), a macromolecular assembly composed of viral non-structural proteins and cellular co-factors. Inhibitors of the HCV NS5A protein block formation of new RCs but do not affect RNA synthesis by pre-formed RCs. Without new RC formation, existing RCs turn over and are eventually lost from the cell.

MAVS-dependent host species range and pathogenicity of human hepatitis A virus.

Hepatotropic viruses are important causes of human disease, but the intrahepatic immune response to hepatitis viruses is poorly understood because of a lack of tractable small- animal models. We describe a murine model of hepatitis A virus (HAV) infection that recapitulates critical features of type A hepatitis in humans. We demonstrate that the capacity of HAV to evade MAVS-mediated type I interferon responses defines its host species range.

Considerations of Environmentally Relevant Test Conditions for Improved Evaluation of Ecological Hazards of Engineered Nanomaterials.

Engineered nanomaterials (ENMs) are increasingly entering the environment with uncertain consequences including potential ecological effects. Various research communities view differently whether ecotoxicological testing of ENMs should be conducted using environmentally relevant concentrations-where observing outcomes is difficult-versus higher ENM doses, where responses are observable. What exposure conditions are typically used in assessing ENM hazards to populations? What conditions are used to test ecosystem-scale hazards? What is known regarding actual ENMs in the environment, via measurements or modeling simulations? How should exposure conditions, ENM transformation, dose, and body burden be used in interpreting biological and computational findings for assessing risks? These questions were addressed in the context of this critical review.

Protease Inhibitors Block Multiple Functions of the NS3/4A Protease-Helicase during the Hepatitis C Virus Life Cycle.

Unlabelled: Hepatitis C virus (HCV) NS3 is a multifunctional protein composed of a protease domain and a helicase domain linked by a flexible linker. Protease activity is required to generate viral nonstructural (NS) proteins involved in RNA replication. Helicase activity is required for RNA replication, and genetic evidence implicates the helicase domain in virus assembly.

Mechanisms of drug photobinding to proteins: photobinding of suprofen to human serum albumin.

Photobinding of drugs to biomolecules constitutes an important early event in the onset of photoallergy. In the present work, UV irradiation of human serum albumin in the presence of either suprofen (SUP) or its major photoproduct, decarboxylated suprofen (DSUP), has been studied as a model system for drug-photosensitised protein binding. Both dark binding and binding in the presence of light were investigated since this will affect the mode, site and mechanism of drug interaction with the protein.

Photobinding of ketoprofen in vitro and ex vivo.

Ketoprofen (KP), a non-steroidal anti-inflammatory drug of the 2-aryl propionic class, has been shown to produce photoallergic side effects as well as cutaneous photosensitizing properties that induce other phototoxic effects. In the present study we investigated photobinding of ketoprofen to both human serum albumin (HSA), a model protein, and to ex vivo pig skin and its photodegradation. Results demonstrate that photoadduct formation and photodegradation progressively increased with irradiation time where they reach a maximum.

Photobinding of carprofen to protein.

Carprofen is a non-steroidal antiinflammatory drug with marked photosensitising properties. In order to elucidate the mechanisms underlying the phenomenon of drug-protein photobinding, mixtures of the drug and human serum albumin were irradiated under different experimental conditions. After irradiation and subsequent gel-filtration chromatography of the photomixture, the eluting protein fraction was analysed by means of fluorescence spectroscopy.

Evaluation of mechanistic in vitro tests for the discrimination of photoallergic and photoirritant potential.

Photochemical tests were used to discriminate photoallergens and photoirritants. UV absorption spectrometry was employed to identify chemicals which absorbed sunlight wavelengths and which required further testing. Photoallergic potential was assessed by studying photobinding of the test chemicals to human serum albumin.

Comparison of an in vitro cellular phototoxicity model against controlled clinical trials of fluoroquinolone skin phototoxicity.

Many therapeutic drugs induce phototoxic skin responses following exposure to solar or artificial ultraviolet radiation sources. Several in vitro model systems have been developed to predict drug phototoxicity but none have been conducted in parallel with controlled clinical phototoxicity studies on systemically administered pharmaceuticals. The in vitro phototoxicity of eight fluoroquinolone (FQ) antibiotics (ciprofloxacin, grepafloxacin, lomefloxacin, norfloxacin, ofloxacin, trovafloxacin, BAYy3118, moxifloxacin) was determined by exposing Chinese hamster fibroblasts to UVA radiation.

A Study on UV Filter Chemicals from Annex VII of European Union Directive 76/768/EEC, in the In Vitro 3T3 NRU Phototoxicity Test.

In 1996, the Scientific Committee on Cosmetology of DGXXIV of the European Commission asked the European Centre for the Validation of Alternative Methods to test eight UV filter chemicals from the 1995 edition of Annex VII of Directive 76/768/EEC in a blind trial in the in vitro 3T3 cell neutral red uptake phototoxicity (3T3 NRU PT) test, which had been scientifically validated between 1992 and 1996. Since all the UV filter chemicals on the positive list of EU Directive 76/768/EEC have been shown not to be phototoxic in vivo in humans under use conditions, only negative effects would be expected in the 3T3 NRU PT test. To balance the number of positive and negative chemicals, ten phototoxic and ten non-phototoxic chemicals were tested under blind conditions in four laboratories.

The International EU/COLIPA In Vitro Phototoxicity Validation Study: Results of Phase II (Blind Trial). Part 1: The 3T3 NRU Phototoxicity Test.

To date, no standardized international guideline for the testing of chemicals for phototoxic potential has been accepted for regulatory purposes. In 1991, the European Commission (EC), represented initially by the Directorate General XI and later by ECVAM (the European Centre for the Validation of Alternative Methods) and COLIPA (the European Cosmetic, Toiletry and Perfumery Association), agreed to establish a joint EU/COLIPA programme on the development and validation of in vitro phototoxicity tests. The first phase (phase I, 1992-93) was designed as a prevalidation study, to identify in vitro test procedures and test protocols for a formal validation trial under blind conditions.

Photomutagenicity assays in bacteria: factors affecting assay design and assessment of photomutagenic potential of para-aminobenzoic acid.

Photomutagenicity assays are required for regulatory submissions of some chemicals. As yet there are no well-validated protocols available for these assays. Critical factors which may contribute to the ability of a bacterial assay to detect photomutagens (e.

EEC/COLIPA project on in vitro phototoxicity testing: First results obtained with a Balb/c 3T3 cell phototoxicity assay.

In a joint validation project eight laboratories from the European Cosmetic Industry Association (COLIPA) as well as FRAME (England) and ZEBET (Germany) are trying to develop validated in vitro methods to be incorporated into new international guidelines for acute phototoxicity testing. The first stage of the study involved selection of the most promising in vitro phototoxicity tests for further validation. 20 chemicals with known phototoxic properties (12 phototoxins, four UV-absorbing non-phototoxins and four non-UV absorbing non-phototoxins) were tested under identical conditions of UV exposure conditions (sun simulator, UVA 5 J/cm(2)) in a standardized cytotoxicity assay with Balb/c 3T3 fibroblasts (endpoint: neutral red uptake, NRU).

A screen for photoirritants in cultured cells.

Adverse photoirritant or photoallergic reactions may be caused by the interaction of certain chemicals with light. The behaviour of 20 chemicals (of which 12 were known UV absorbers and photoirritants, four were known UV absorbers and non-photoirritants and four were known non-UV-absorbers and non-photoirritants) have been screened in an in vitro photoirritation assay using cultured cells [3T3 neutral red uptake (NRU) assay]. Treated cells were exposed to UVA (5 J/cm(2) in 50 min) and visible light in Earle's balanced salt solution and compared with dark controls.

A scheme for in vitro screening of substances for photoallergenic potential.

Safety tests for photoallergenicity have to date used animal models, but in vitro testing, based on mechanistic knowledge, should now be considered. A photoallergen must absorb the wavelengths of light present in sunlight, and after light absorption the molecule must photobind to protein. In contrast, many photoirritants produce excited state singlet oxygen, which causes damage such as oxidation of certain amino-acid residues.