COVID-19 and Lung Mast Cells: The Kallikrein–Kinin Activation Pathway

Mast cells (MCs) have relevant participation in inflammatory and vascular hyperpermeability events, responsible for the action of the kallikrein–kinin system (KKS), that affect patients inflicted by the severe form of COVID-19. Given a higher number of activated MCs present in COVID-19 patients and their association with vascular hyperpermeability events, we investigated the factors that lead to the activation and degranulation of these cells and their harmful effects on the alveolar septum environment provided by the action of its mediators. Therefore, the pyroptotic processes throughout caspase-1 (CASP-1) and alarmin interleukin-33 (IL-33) secretion were investigated, along with the immunoexpression of angiotensin-converting enzyme 2 (ACE2), bradykinin receptor B1 (B1R) and bradykinin receptor B2 (B2R) on post-mortem lung samples from 24 patients affected by COVID-19. The results were compared to 10 patients affected by H1N1pdm09 and 11 control patients. As a result of the inflammatory processes induced by SARS-CoV-2, the activation by immunoglobulin E (IgE) and degranulation of tryptase, as well as Toluidine Blue metachromatic (TB)-stained MCs of the interstitial and perivascular regions of the same groups were also counted. An increased immunoexpression of the tissue biomarkers CASP-1, IL-33, ACE2, B1R and B2R was observed in the alveolar septum of the COVID-19 patients, associated with a higher density of IgE⁺ MCs, tryptase⁺ MCs and TB-stained MCs, in addition to the presence of intra-alveolar edema. These findings suggest the direct correlation of MCs with vascular hyperpermeability, edema and diffuse alveolar damage (DAD) events that affect patients with a severe form of this disease. The role of KKS activation in events involving the exacerbated increase in vascular permeability and its direct link with the conditions that precede intra-alveolar edema, and the consequent DAD, is evidenced. Therapy with drugs that inhibit the activation/degranulation of MCs can prevent the worsening of the prognosis and provide a better outcome for the patient.     

Theophylline: Old Drug in a New Light,Application in COVID-19 through Computational Studies

Theophylline (3-methyxanthine) is a historically prominent drug used to treat respiratory diseases, alone or in combination with other drugs. The rapid onset of the COVID-19 pandemic urged the development of effective pharmacological treatments to directly attack the development of new variants of the SARS-CoV-2 virus and possess a therapeutical battery of compounds that could improve the current management of the disease worldwide. In this context, theophylline, through bronchodilatory, immunomodulatory, and potentially antiviral mechanisms, is an interesting proposal as an adjuvant in the treatment of COVID-19 patients. Nevertheless, it is essential to understand how this compound could behave against such a disease, not only at a pharmacodynamic but also at a pharmacokinetic level. In this sense, the quickest approach in drug discovery is through different computational methods, either from network pharmacology or from quantitative systems pharmacology approaches. In the present review, we explore the possibility of using theophylline in the treatment of COVID-19 patients since it seems to be a relevant candidate by aiming at several immunological targets involved in the pathophysiology of the disease. Theophylline down-regulates the inflammatory processes activated by SARS-CoV-2 through various mechanisms, and herein, they are discussed by reviewing computational simulation studies and their different applications and effects.     

A satellite remote-sensing multi-index approach to discriminate pelagic Sargassum in the waters of the Yucatan Peninsula,Mexico

Recently, the need for quantitative information on the spatiotemporal distribution of floating macroalgae, particularly the two species of genus Sargassum, has grown because of blooms of these species in the Gulf of Mexico and Caribbean Sea. Remote sensing is one of the most frequently used tools to assess pelagic Sargassum distribution. The purpose of this study was to implement a methodological approach to detect floating algae in an efficient and replicable manner at a moderate cost. We analyzed Landsat 8 imagery, from which we calculated four vegetation indices and one floating-algae index to implement a supervised classification, together with the bands 2 and 5, using the Random Forest algorithm. The analysis was performed monthly from 2014 to 2015 for the northeastern Yucatan Peninsula, Mexico, with a total of 91 analyzed images. The quantitative performance metrics of the classifier (overall, Kappa and Tau) were greater than 80%, whereas bands 2 and 5 as well as the atmospherically resistant vegetation index made the greatest contributions to the classifications. During summer 2015, more than 4,000 ha of Sargassum coverage per image were observed, which was substantially greater than that over the rest of the period. This approach constitutes a transferable alternative for the systematic detection of Sargassum, which enables a quantitative semi-automated time series comparison.     

Circadian Rhythm Dysregulation and Leukemia Development: The Role of Clock Genes as Promising Biomarkers

The circadian clock (CC) is a daily system that regulates the oscillations of physiological processes and can respond to the external environment in order to maintain internal homeostasis. For the functioning of the CC, the clock genes (CG) act in different metabolic pathways through the clock-controlled genes (CCG), providing cellular regulation. The CC’s interruption can result in the development of different diseases, such as neurodegenerative and metabolic disorders, as well as cancer. Leukemias correspond to a group of malignancies of the blood and bone marrow that occur when alterations in normal cellular regulatory processes cause the uncontrolled proliferation of hematopoietic stem cells. This review aimed to associate a deregulated CC with the manifestation of leukemia, looking for possible pathways involving CG and their possible role as leukemic biomarkers.     

Investigation of the properties of niobium pentoxide for use in dye-sensitized solar cells

This work demonstrates the obtention of Nb₂O₅ nanoparticles by the microwave-assisted hydrothermal synthesis method in a fast way and with the use of low temperatures. The heat treatment applied on the samples promotes the phase change in Nb₂O₅ from pseudohexagonal to orthorhombic as the temperature increases, with a particle size between 7.3 and 32.6 nm. The band gap of the samples decreases with increasing temperature, obtaining a minimum value of 3.04 eV at 800°C. Dye-sensitized solar cells (DSSC) were assembled using the Doctor Blade coating technique. The photovoltaic parameters of open-circuit voltage (Voc) and short-circuit current density (Jsc) were evaluated. The cells showed a photovoltaic response, demonstrating that Nb₂O₅ has a semiconductive potential. The DSSC have different characteristics regarding Jsc and Voc, showing that according to the temperature increase in the semiconductor sample, there is a decrease in the photovoltaic parameters of the cells.     

Synthesis and characterization of cellulose acetate from royal palm tree agroindustrial waste

This study provides a novel value‐added utilization of the agroindustrial waste of royal palm tree leaf sheath to produce cellulose acetate. One of the motivations of this work was the fact that Brazil is one of the largest heart of palm producers in the world. However, as a result of extraction and processing, tons of waste are generated and discharged to the environment. Such waste is rich in lignocellulosic material, which could be reused to obtain derivatives of interest and commercial value. The synthesis of cellulose acetate was performed through a homogeneous acetylation reaction. Three different conditions were tested for delignification of the raw material, which resulted in a reduction in lignin content from 17.75 to 7.72%. The highest yield of cellulose acetate reached 99.5%, with degree of substitutions ranging between 2.08 and 2.82, which indicates satisfactory conversion. The Fourier transform infrared spectrum showed that practically all hydroxyl groups were replaced by acetate groups; this was also confirmed by nuclear magnetic resonance analysis. X‐ray diffraction analysis showed that the cellulose acetate crystallinity index was 8.9%. This demonstrates the viable potential of cellulose acetate production with low cost and use of highly available agroindustrial waste. POLYM. ENG. SCI., 59:891–898, 2019. © 2018 Society of Plastics Engineers     

Eumelanin for nature‐inspired UV‐absorption enhancement of plastics

In the human body, the black‐brown biopigment eumelanin blocks harmful ultraviolet (UV) radiation. In the plastics industry, additives are often added to polymers to increase their UV‐absorption properties. We herein report an assessment of the biopigment eumelanin as a nature‐inspired additive for plastics to enhance their UV absorption. Since eumelanin is produced by natural sources and is nontoxic, it is an interesting candidate in the field of sustainable plastic additives. In this work, the eumelanin‐containing films of commercial ethylene–vinyl acetate copolymer, a plastic used for packaging applications, were obtained by melt compounding and compression molding. The biopigment dispersion in the films was improved by means of the melanin free acid treatment. It was observed that eumelanin amounts as low as 0.8 wt% caused an increase of the UV absorption, up to one order of magnitude in the UVA range. We also evaluated the effect of eumelanin on the thermal stability and photostability of the films: the biopigment proved to be double‐edged, working both as UV‐absorption enhancer and photo‐prooxidant, as thermogravimetric analysis and infrared spectroscopy revealed. © 2019 Society of Chemical Industry     

Chitosan impregnated gutta-percha points: antimicrobial in vitro evaluation and mechanical properties

Chitosan-impregnated gutta-percha points (ChitGPP) were tested for their ability to inhibit the growth of microorganisms usually involved in root canal infections. Their mechanical properties were also studied and compared with the commonly used commercial points in endodontics. ChitGPP were more efficient in reducing the microbial load than those without chitosan. ChitGPP also possess better tensile and elastic properties than commercial ones. After six months of storage, ChitGPP’s were still able to reduce the bacterial load by 1 log, suggesting that impregnation of gutta-percha points with chitosan could be a good alternative to obtain gutta-percha points with improved antimicrobial properties.     

Photo-fenton and UV photo degradation of naphthalene with zero- and two-valent iron in the presence of persulfate

An initial set of 12 kinetic experiments was carried out to remove naphthalene from an aqueous effluent by photo-Fenton involving Fe⁰ and Fe²⁺ at two different concentrations of H₂O₂ (150 and 300?mg?L^?1) and three different pHs (3, 5, and 7) (2²×3¹ experiments). The rate constants (k) for the reaction of naphthalene degradation by involving Fe²⁺ as reactant were in general higher than those with Fe⁰, but the use of Fe²⁺ increased the concentration of naphthalene at equilibrium (C_e) when compared with the same response obtained with Fe⁰ at analogous conditions. A second set of twelve kinetic experiments of photo-Fenton degradation was also performed with persulfate as additive at the conditions already reported, but at a constant concentration of H₂O₂ of 150?mg?L^?1 (2¹×3¹ experiments with NaCl +2¹×3¹ experiments without NaCl). In almost all the runs in which only the source of iron was varied, k from the kinetic data involving Fe²⁺ was higher than that involving Fe⁰, but no difference was observed in terms of C_e that was always zero. The addition of persulfate to treat the effluent either containing or not containing salt enhanced the chemical kinetics, and shifted the equilibrium toward the full removal of naphthalene. A final set of nine experiments of UV photo degradation of naphthalene by involving persulfate without iron, with Fe⁰ and Fe²⁺ in the pH range from 3 to 7 (3² experiments) mainly showed that the use of H₂O₂ may be avoided to remove rapidly and completely naphthalene from wastewater.