- Design Principles, Sensing Mechanisms, and Applications of Highly Specific Fluorescent Probes for HOCl/OCl. [Journal Article]
- ACAcc Chem Res 2019 Jul 18
- Hypochlorous acid/hypochlorite (HOCl/OCl-), one of the most important reactive oxygen species (ROS), plays vital roles in various physiological and pathological processes. At normal concentrations, O…
Hypochlorous acid/hypochlorite (HOCl/OCl-), one of the most important reactive oxygen species (ROS), plays vital roles in various physiological and pathological processes. At normal concentrations, OCl- acts as part of an immune defense system by destroying invasive bacteria and pathogens. However, nonproperly located or excessive amounts of OCl- are related to many diseases, including cancers. Thus, detection of OCl- has great importance. Owing to their high sensitivities, selectivities, fast response times, technical simplicities, and high temporal and spatial resolution, fluorescent probes are powerful tools for in vitro and in vivo sensing of target substances. This Account focuses on the development of new chemosensors for detection of OCl-, which operate by undergoing a chemical reaction with this ROS in conjunction with a change in emission properties. As part of the presentation, we first introduce several important factors that need to be considered in the design of fluorescent chemosensors for OCl-, including fluorophores, reaction groups, cosolvents, and buffers. Discussion here revolves around the need to select fluorophores that resist oxidation by OCl-. As well, attention is given to the sensitivities and selectivities of groups in the sensors that react with OCl- to trigger a fluorescence response. Moreover, well-known reaction groups, which react with highly reactive ROS (hROS), have been redesigned to be specific for OCl-. In addition, it is pointed out that several cosolvents and buffers such as DMSO and HEPES are not suitable for use in systems for the detection of OCl- because they are readily oxidized by this ROS. We further discuss recent investigations carried out by us and others aimed at the development of fluorescent probes for in vitro and in vivo detection of OCl-. These efforts led to the new "dual lock" strategy for designing OCl- chemosensors as well as several new specific reaction groups such as imidazoline-2-thiones and imidazoline-2-boranes. Probes created using this strategy and the new reacting groups have been successfully applied to imaging exogenous and endogenous OCl- in live cells and/or tissues. The design concepts and strategies emanating from our studies of fluorescent OCl- probes have provided insight into the general field of fluorescent probes. Despite the progress made thus far, challenges still remain in developing and applying fluorescent OCl- probes. For example, more highly specific and sensitive fluorescent OCl- probes are still in great demand for studies of the biological roles played by OCl-. Thus, interdisciplinary collaborations of chemists, biologists, and medical practitioners are needed to drive future developments of OCl- probes for disease diagnosis and drug screening.
- Conservation of the structure and function of bacterial tryptophan synthases. [Journal Article]
- IIUCrJ 2019 Jul 01; 6(Pt 4):649-664
- Tryptophan biosynthesis is one of the most characterized processes in bacteria, in which the enzymes from Salmonella typhimurium and Escherichia coli serve as model systems. Tryptophan synthase (TrpA…
Tryptophan biosynthesis is one of the most characterized processes in bacteria, in which the enzymes from Salmonella typhimurium and Escherichia coli serve as model systems. Tryptophan synthase (TrpAB) catalyzes the final two steps of tryptophan biosynthesis in plants, fungi and bacteria. This pyridoxal 5'-phosphate (PLP)-dependent enzyme consists of two protein chains, α (TrpA) and β (TrpB), functioning as a linear αββα heterotetrameric complex containing two TrpAB units. The reaction has a complicated, multistep mechanism resulting in the β-replacement of the hydroxyl group of l-serine with an indole moiety. Recent studies have shown that functional TrpAB is required for the survival of pathogenic bacteria in macrophages and for evading host defense. Therefore, TrpAB is a promising target for drug discovery, as its orthologs include enzymes from the important human pathogens Streptococcus pneumoniae, Legionella pneumophila and Francisella tularensis, the causative agents of pneumonia, legionnaires' disease and tularemia, respectively. However, specific biochemical and structural properties of the TrpABs from these organisms have not been investigated. To fill the important phylogenetic gaps in the understanding of TrpABs and to uncover unique features of TrpAB orthologs to spearhead future drug-discovery efforts, the TrpABs from L. pneumophila, F. tularensis and S. pneumoniae have been characterized. In addition to kinetic properties and inhibitor-sensitivity data, structural information gathered using X-ray crystallo-graphy is presented. The enzymes show remarkable structural conservation, but at the same time display local differences in both their catalytic and allosteric sites that may be responsible for the observed differences in catalysis and inhibitor binding. This functional dissimilarity may be exploited in the design of species-specific enzyme inhibitors.
- Human Oral Epithelial Cells Impair Bacteria-Mediated Maturation of Dendritic Cells and Render T Cells Unresponsive to Stimulation. [Journal Article]
- FIFront Immunol 2019; 10:1434
- The oral mucosa is a first line of defense against pathogenic organisms and yet tolerates food antigens and resident bacteria. Mucosal epithelial cells are emerging as important regulators of innate …
The oral mucosa is a first line of defense against pathogenic organisms and yet tolerates food antigens and resident bacteria. Mucosal epithelial cells are emerging as important regulators of innate and adaptive immune responses. However, the contribution of oral epithelial cells (OECs) determining oral immunity is understudied. Here, we evaluated the ability of H413 and TR146 cells, two OEC lines derived from human oral squamous cell carcinomas, and primary OECs to modulate immune responses to a cocktail of Gram+ and Gram- bacteria known as MV130. OECs expressed CD40 constitutively and class II major histocompatibility complex (MHC II) molecules when stimulated with IFNγ, but not CD80 or CD86. Dendritic cells (DCs) treated with bacteria in co-culture with OECs did not fully mature, as judged by the expression of MHC II, CD80 and CD86, and barely released IL-12 and TNFα, compared to control DCs. Furthermore, in the presence of OECs, DCs were unable to stimulate allogenic naive CD4 T cells to produce IFNγ and TNFα. Similarly, OECs in culture with total CD4 T cells or Th1 cells stimulated with anti-CD3 and anti-CD28 antibodies abrogated CD25 and CD69 expression, T cell proliferation and the release of IFNγ and TNFα. The inhibition on T cell activation by OECs was cell-contact dependent, TGFβ independent and largely irreversible. Overall, this behavior of OECs is likely key to avoid immune system over-reaction against resident bacteria.
- Preparation of a novel monoclonal antibody against caprine interleukin-17A and its applications in immunofluorescence and immunohistochemistry assays. [Journal Article]
- BBBMC Biotechnol 2019 Jul 17; 19(1):47
- CONCLUSIONS: The monoclonal antibody mAb H8 prepared in this study may be a potential tool for the detection of cIL-17A and beneficial for investigating the pathogenesis of various IL-17-associated diseases.
- Towards understanding the effects of heat and humidity on ageing of a NASA standard pyrotechnic igniter. [Journal Article]
- SRSci Rep 2019 Jul 15; 9(1):10203
- Ageing of pyrotechnic substance, primarily fuel oxidisation, can cause changes in composition that degrade their performance. This study investigates the effect of ageing on zirconium potassium perch…
Ageing of pyrotechnic substance, primarily fuel oxidisation, can cause changes in composition that degrade their performance. This study investigates the effect of ageing on zirconium potassium perchlorate (ZPP), a widely used NASA Standard Initiator. Although prior studies have investigated the effects of accelerated ageing on ZPP, this is the first to conduct kinetic analyses at different relative humidity (RH) levels. Here, both thermal and kinetic analyses are conducted for a variety of hygrothermal ageing cases in order to replicate the natural ageing process. X-ray photoelectron spectroscopy (XPS) results reveal that oxidant levels drop and zirconium dioxide levels rise as ZPP ages. Lower heats of reaction and increases in activation energy were also observed under the RH conditions. Calculations using van't Hoff equation indicate that moisture shortened the lifespan of the unaged ZPP up to about 85% under extreme RH conditions, while significantly deteriorating the heat of reaction, sensitivity, and thus increased the risk of a misfire.
- Neuronal Nitric Oxide Mediates the Anti-Inflammatory Effects of Intestinal Ischemic Preconditioning. [Journal Article]
- JSJ Surg Res 2019 Jul 10; 244:241-250
- CONCLUSIONS: Our data demonstrate that NO generated by intestinal nNOS plays a pivotal role in IPC-linked tissue protection by inhibiting an IR-related acute inflammatory response.
- Molecular and functional characterization of a mannose-binding lectin/ficolin-associated protein (MAp44) from Nile tilapia (Oreochromis niloticus) involved in the immune response to bacterial infection. [Journal Article]
- DCDev Comp Immunol 2019 Jul 09; 101:103438
- The lectin pathway of the complement system has a pivotal role in the defense against infectious organisms. Mannose-binding lectin/ficolin-associated protein (MAp44), a multifunctional complement reg…
The lectin pathway of the complement system has a pivotal role in the defense against infectious organisms. Mannose-binding lectin/ficolin-associated protein (MAp44), a multifunctional complement regulator, regulates the complement activation by competing with MASP-1, MASP-2 and MASP-3 for MBL and ficolin binding sites. In this study, we described the identification and functional characterization of a MAp44 homologue (OnMAp44) from Nile tilapia (Oreochromis niloticus) at molecular, cellular and protein levels. The open reading frame (ORF) of OnMAp44 is 1140 bp of nucleotide sequence encoding a polypeptide of 379 amino acids. The deduced amino acids sequence has four characteristic structures, including two C1r/C1s-Uegf-BMP domains (CUB), one epidermal growth factor domain (EGF) and one complement control protein domains (CCP). Expression analysis revealed that the OnMAp44 was highly expressed in liver, and widely existed in other examined tissues. In addition, the OnMAp44 expression was significantly up-regulated in spleen and head kidney following challenges with Streptococcus agalactiae and Aeromonas hydrophila. The up-regulations of OnMAp44 mRNA and protein expression were also observed in hepatocytes and monocytes/macrophages in vitro stimulation with S. agalactiae and A. hydrophila. Recombinant OnMAp44 protein was able to participate in the regulation of inflammation and migration reaction. Taken together, the results indicated that OnMAp44 was likely to involve in the immune response to bacterial infection in Nile tilapia.
- Selenized Plant Oil Is an Efficient Source of Selenium for Selenoprotein Biosynthesis in Human Cell Lines. [Journal Article]
- NNutrients 2019 Jul 04; 11(7)
- Selenium is an essential trace element which is incorporated in the form of a rare amino acid, the selenocysteine, into an important group of proteins, the selenoproteins. Among the twenty-five selen…
Selenium is an essential trace element which is incorporated in the form of a rare amino acid, the selenocysteine, into an important group of proteins, the selenoproteins. Among the twenty-five selenoprotein genes identified to date, several have important cellular functions in antioxidant defense, cell signaling and redox homeostasis. Many selenoproteins are regulated by the availability of selenium which mostly occurs in the form of water-soluble molecules, either organic (selenomethionine, selenocysteine, and selenoproteins) or inorganic (selenate or selenite). Recently, a mixture of selenitriglycerides, obtained by the reaction of selenite with sunflower oil at high temperature, referred to as Selol, was proposed as a novel non-toxic, highly bioavailable and active antioxidant and antineoplastic agent. Free selenite is not present in the final product since the two phases (water soluble and oil) are separated and the residual water-soluble selenite discarded. Here we compare the assimilation of selenium as Selol, selenite and selenate by various cancerous (LNCaP) or immortalized (HEK293 and PNT1A) cell lines. An approach combining analytical chemistry, molecular biology and biochemistry demonstrated that selenium from Selol was efficiently incorporated in selenoproteins in human cell lines, and thus produced the first ever evidence of the bioavailability of selenium from selenized lipids.
- Identification and functional analysis of an iron-binding protein, ferritin heavy chain subunit, from the swallowtail butterfly, Papilio xuthus. [Journal Article]
- AIArch Insect Biochem Physiol 2019 Jul 05; :e21592
- Ferritin, which is ubiquitous among all living organisms, plays a crucial role in maintaining iron homeostasis, immune response, and detoxification. In the present research, we identified an iron-bin…
Ferritin, which is ubiquitous among all living organisms, plays a crucial role in maintaining iron homeostasis, immune response, and detoxification. In the present research, we identified an iron-binding protein, ferritin heavy chain subunit, from Papilio xuthus and named PxFerHCH. The complete complementary DNA of PxFerHCH was 1,252 bp encoding a sequence of 211 amino acids, which includes an iron-responsive element. Phylogenetic analysis showed that PxFerHCH is clustered with Manduca sexta and Galleria mellonella ferritin heavy chain subunits. Expression levels of PxFerHCH in various tissues were analyzed by reverse transcription quantitative polymerase chain reaction, and the results exhibited that PxFerHCH was expressed in all tissues with the highest expression in the fat body. The relative expression level of PxFerHCH in response to bacterial (Escherichia coli and Staphylococcus aureus) challenges sharply increased by about 12 hr postinfection (hpi) and then decreased at 24 hpi. In addition, the iron-binding capacity and antioxidation activity of recombinant PxFerHCH protein were also investigated. These results reveal that PxFerHCH might play an important role in defense against bacterial infection.
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- Catalytic reaction system for rapid selective oxidation of alkyl sulphide. [Journal Article]
- JHJ Hazard Mater 2019 Jun 26; 379:120830
- Highly efficient catalytic reaction systems are developed to rapidly and selectively oxidize 2-chloroethyl ethyl sulfide (CEES). In the systems, precursors containing bromide(s) and nitrate anions ar…
Highly efficient catalytic reaction systems are developed to rapidly and selectively oxidize 2-chloroethyl ethyl sulfide (CEES). In the systems, precursors containing bromide(s) and nitrate anions are chosen for the development of cyclic catalytic loop and the effect of acids on the selective oxidation of CEES are investigated by the addition of several homogeneous acid catalysts. The experimental results reveal that addition of acid results in a higher concentration of tribromide, which is reported as a key component for the observed activity in the catalytic solution. As a consequence, a dramatic improvement in catalytic activity is observed, especially when the molar amount of acid is controlled to be more than twice the initial concentration of tribromide. For the efficient design of a catalytic system, heterogeneous acid catalysts possessing different ratios of Brønsted to Lewis acid sites are also considered. Compared to reaction systems catalysed by homogeneous acids, similar reaction behaviour is observed for the reaction with Amerlyst-15, while those with other heterogeneous catalysts, containing Lewis or mixed acid sites in their structure, exhibits an adverse effect of selective sulfoxidation, mainly due to the adsorption of anions onto Lewis sites and consequential deconstruction of the catalytic loop.