The paper demonstrates the feasibility of the gel-clot method for the analysis of bacterial endotoxins in water extracts of ultrapure paraffin oil which is a water insoluble oily medical device. ...Because ultrapure paraffin oil is water insoluble oily liquid, the ultrapure paraffin oil (10 mL) was shaken with 10 mL water for 15 minutes at 2000 rpm, the endotoxin present was extracted to the aqueous phase without interference inhibition/enhancement of the product, the recovery of the endotoxin added to the ultrapure paraffin oil was determined. A validation study confirmed that endotoxins present in ultrapure paraffin oil which is water insoluble liquid medical device pass over into the aqueous phase at concentrations of 20, 10, and 5 EU/mL with recoveries of 94.2% to 111%. So the conclusion is that the gel-clot test is suitable for detecting bacterial endotoxins in ultrapure paraffin oil which is a water insoluble oily medical device.
Polyamines (PAs) are low molecular weight aliphatic nitrogenous bases containing two or more amino groups. They are produced by organisms during metabolism and are present in almost all cells. ...Because they play important roles in diverse plant growth and developmental processes and in environmental stress responses, they are considered as a new kind of plant biostimulant. With the development of molecular biotechnology techniques, there is increasing evidence that PAs, whether applied exogenously or produced endogenously via genetic engineering, can positively affect plant growth, productivity, and stress tolerance. However, it is still not fully understood how PAs regulate plant growth and stress responses. In this review, we attempt to cover these information gaps and provide a comprehensive and critical assessment of the published literature on the relationships between PAs and plant flowering, embryo development, senescence, and responses to several (mainly abiotic) stresses. The aim of this review is to summarize how PAs improve plants' productivity, and to provide a basis for future research on the mechanism of action of PAs in plant growth and development. Future perspectives for PA research are also suggested.
Conspectus Aromaticity, one of the most fundamental concepts in chemistry, has attracted considerable attention from both theoreticians and experimentalists. Much effort on aromaticity in ...organometallics has been devoted to metallabenzene and derivatives. In comparison, aromaticity in other organometallics is less developed. This Account describes how our group has performed quantum chemical calculations to examine aromaticity in recently synthesized novel organometallic complexes. By collaborations with experimentalists, we have extended several aromaticity concepts into organometallics to highlight the power of transition metals. In general, the transition metal could participate in delocalization either out of rings or in the rings. We examined the former by probing the possibility of transition metal substituents in hyperconjugative aromaticity, where the metal is out of the rings. Calculations on tetraaurated heteroaryl complexes reveal that incorporation of the aurated substituents at the nitrogen atom can convert nonaromaticity in the parent indolium into aromaticity in the aurated one due to hyperconjugation, thus extending the concept of hyperconjugative aromaticity to heterocycles with transition metal substituents. More importantly, further analysis indicates that the aurated substituents can perform better than traditional main-group substituents. Recently, we also probed the strongest aromatic cyclopentadiene and pyrrolium rings by hyperconjugation of transition metal substituents. Moreover, theoretical calculations suggest that one electropositive substituent is able to induce aromaticity; whereas one electronegative substituent prompts nonaromaticity rather than antiaromaticity. We also probed the possibility of Craig-type Möbius aromaticity in organometallic chemistry, where the position of the transition metals is in the rings. According to the electron count and topology, aromaticity can be classified as Hückel-type and Möbius-type. In comparison with numerous Hückel aromatics containing 4n+2 π-electrons, Möbius aromatics with 4n π-electrons, especially the Craig-type species, are particularly limited. We first examined aromaticity in osmapentalynes. Theoretical calculations reveal that incorporation of the osmium center not only reduces the ring strain of the parent pentalyne, but also converts Hückel antiaromaticity in the parent pentalyne into Craig-type Möbius aromaticity in metallapentalynes. Further studies show that the transition metal fragments can also make both 16e and 18e osmapentalenes aromatic, indicating that the Craig-type Möbius aromaticity in osmapentalyne is rooted in osmapentalenes. In addition, Möbius aromaticity is also possible in dimetalla10annulenes, where the lithium atoms are not spectator cations but play an important role due to their bonding interaction with the diene moieties. We then examined the possibility of σ-aromaticity in an unsaturated ring. Traditional π-aromaticity is used to describe the π-conjugation in fully unsaturated rings; whereas σ-aromaticity may stabilize fully saturated rings with delocalization caused by σ-electron conjugation. We found that the unsaturated three-membered ring in cyclopropaosmapentalene is σ-aromatic. Very recently, we extended σ-aromaticity into in a fully unsaturated ring. The concepts and examples presented here show the importance of interplay and union between experiment and theory in developing novel aromatic systems and, especially, the indispensable role of computational study in rationalization of unconventional aromaticity. All these findings highlight the strong power of transition metals originating from participation of d orbitals in aromaticity, opening an avenue to the design of unique metalla-aromatics.
The research employed network toxicology and molecular docking techniques to systematically examine the potential carcinogenic effects and mechanisms of aspartame (L-α-aspartyl-L-phenylalanine methyl ...ester). Aspartame, a commonly used synthetic sweetener, is widely applied in foods and beverages globally. In recent years, its safety issues, particularly the potential carcinogenic risk, have garnered widespread attention. The study first constructed an interaction network map of aspartame with gastric cancer targets using network toxicology methods and identified key targets and pathways. Preliminary validation was conducted through microarray data analysis and survival analysis, and molecular docking techniques were employed to further examine the binding affinity and modes of action of aspartame with key proteins. The findings suggest that aspartame has the potential to impact various cancer-related proteins, potentially raising the likelihood of cellular carcinogenesis by interfering with biomolecular function. Furthermore, the study found that the action patterns and pathways of aspartame-related targets are like the mechanisms of known carcinogenic pathways, further supporting the scientific hypothesis of its potential carcinogenicity. However, given the complexity of the in vivo environment, we also emphasize the necessity of validating these molecular-level findings in actual biological systems. The study introduces a fresh scientific method for evaluating the safety of food enhancers and provides a theoretical foundation for shaping public health regulations.
Redox reactions between iron and nitrogen drive the global biogeochemical cycles of these two elements and, concomitantly, change the fate of nutrients in and the mineralogy of the cycles. The ...microbially mediated NO3−-reducing Fe(II) oxidation process (NRFO) plays a key role in Fe/N interactions under neutral-anoxic conditions. Microbially mediated NRFO was considered a biological process, yet recently it has been documented that chemical mechanisms are also at play. However, the relative contributions of biological processes and chemical processes to Fe(II) oxidation remain largely unquantified owing to the co-occurrence of the reactions. Herein, the kinetics and secondary minerals of microbially mediated NRFO by Pseudogulbenkiania sp. strain 2002 and Acidovorax sp. strain BoFeN1 were investigated with acetate as electron donor unless otherwise stated. The results of Cells + NO3− suggested the two strains could biologically reduce NO3− to NO3−/NOx/N2O/N2 and concomitantly oxidize acetate and result in cell growth. Fe(II) oxidation and NO3− reduction occurred simultaneously in the presence of Fe(II) (Cells + Fe(II) + NO3−). For strain BoFeN1, the presence of Fe(II) slightly enhanced the NO3− reduction, acetate consumption, and cell growth, all of which were substantially retarded by Fe(II) for strain 2002. When compared with the microbial nitrite reduction, the relatively higher rate of chemical reaction between NO2− and dissolved Fe(II) confirmed the occurrence of chemodenitrification in the microbially mediated NRFO processes. After 5 days’ incubation, no green rust was observed, and lepidocrocite, goethite, and magnetite were observed with the Cells + Fe(II) + NO3− treatment, but only goethite was found with the Fe(II) + NO2−. The spectra for the EPSs + Fe(II) treatment suggested that the oxidized c-Cyts in the EPSs could oxidize Fe(II), which show the theoretical capability of taking electrons from Fe(II) into the cells via c-Cyts. A brief model was established by combining the verified reactions of (1) biological reduction of NO3− to NO2−/NOx/N2O/N2, (2) Fe(II) oxidation by NO2−, and (3) Fe(II) oxidation by c-Cyts in EPSs. Based on the model, the rate constant of Fe(II) oxidation by c-Cyts in EPSs was derived. For nitrite reduction, the relative contribution of biological processes to the nitrite reduction was higher than that of chemodenitrification. For Fe(II) oxidation, the relative contribution of the chemical process via nitrite to Fe(II) oxidation was higher than that of biological processes. These findings provide a quantitative interpretation of the chemodenitrification and biological reactions in the microbially mediated NRFO processes, which could assist the mechanistic understanding of the global biogeochemical cycles of iron and nitrogen in subsurface environments.
An electrochemical sensor based on the composites of Pt nanoparticles modified carbon dots and ionic liquid-functionalized graphene oxide was fabricated for detection of H2O2 with high sensitivity ...and adequate selectivity.
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•Pt nanoparticles-carbon quantum dots (PtNPs-CDs)/IL-graphene oxide (IL-GO)/GCE electrode was used to detect H2O2.•PtNPs-CDs/IL-GO was used as an electrochemical sensing nanocomposite.•Synergistic amplifying effects resulted from combining PtNPs-CDs and IL-GO.•The sensor showed high sensitivity and selectivity, low detection limit and wide linear range to H2O2 using amperometry.•The sensor was used for successful H2O2 determination in real serum samples.
There is current interest in developing carbon nanomaterials, which are a novel kind of nanomaterial, for uses in electrochemical sensing and biosensors. We constructed a novel sensor based on a Pt nanoparticles-carbon quantum dots/ionic liquid functionalized graphene oxide (PtNPs-CDs/IL-GO) nanocomposite for detecting H2O2. We characterized the morphology and electrochemical performance of the modified electrode using scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and cyclic voltammetry, respectively. The unique chemical structure of PtNPs-CDs/IL-GO greatly accelerated the catalysis of H2O2 and provided plenty of active sites for electrochemical redox reactions. Electrochemical experiments demonstrated that the PtNPs-CDs/IL-GO sensor had high selectivity, a wide linear range from 1 to 900μM, and a low detection limit of 0.1μM with respect to the reduction of H2O2. These characteristics indicate good electrical conductivity and high electrocatalytic activity. This simple and effective method has potential applications in chemical sensors and electrochemical catalysis.
MicroRNAs are small non-coding nucleic acids that are responsible for regulating the gene expression by binding to the coding region and 3' and 5' un-translated region of target messenger RNA. ...Approximately 70% of known microRNAs are expressed in the brain and increasing evidences demonstrate the possible involvement of microRNAs in Alzheimer's disease (AD) according to the statistics. The characteristic symptoms of AD are the progressive loss of memory and cognitive functions due to the deposition of amyloid β (Aβ) peptide, intracellular aggregation of hyperphosphorylated Tau protein, the loss of synapses, and neuroinflammation, as well as dysfunctional autophagy. Therefore, microRNA-mediated regulation for above-mentioned changes may be the potential therapeutic strategies for AD. In this review, the role of specific microRNAs involved in AD and corresponding applications are systematically discussed, including positive effects associated with the reduction of Aβ or Tau protein, the protection of synapses, the inhibition of neuroinflammation, the mitigation of aging, and the induction of autophagy in AD. It will be beneficial to develop effective targets for establishing a cross link between pharmacological intervention and AD in the near future.
A Ag3PO4/GO/UiO–66–NH2(AGU) composite photocatalyst was prepared by an ultrasonic-assisted in situ precipitation method. The optical property, structure, composition, and morphology of photocatalysts ...were investigated using UV–vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, electrochemical impedance spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, energy-dispersive spectrometry, transmission electron microscopy, Fourier transform infrared spectroscopy, and charge flow tracking by photodeposition of Pt and PbO2 nanoparticles. In comparison with Ag3PO4 and Ag3PO4/UiO–66–NH2(AU), the AGU composite photocatalyst showed heightened photocatalytic performance for the degradation of levofloxacin hydrochloride (LVF). The AGU photocatalyst (dosage: 0.8 g/L) with 1% mass content of graphene oxide (GO), the mass ratio of Ag3PO4 and UiO–66–NH2(U66N) reached 2:1, showed the highest photodegradation rate of 94.97% for 25 mg/L LVF after 60 min of visible light irradiation at pH = 6. The formation of a heterojunction and the addition of GO synergistically promote faster separation of electron–hole pairs, retain more active substances, and enhance the performance of the photocatalyst. Furthermore, the mechanism of the Z-scheme of the AGU composite photocatalytic is proposed.
Microbial vanadate V(V) reduction is the key process of vanadium geochemical cycling, while the identified functional microbes are rather limited. Considering the structural similarity of ...metavanadate and nitrate, widespread denitrifying bacteria are expected to be able to mediate V(V) reduction, but this process has not been fully understood. This study confirmed the effectiveness of two denitrifying bacteria, i.e., Acidovorax sp. strain BoFeN1 and Pseudogulbenkiania sp. strain 2002, in reducing V(V). During 120-h incubation, the V(V) removal efficiency was 89.0 ± 1.83% and 96.0 ± 1.43% by strain BoFeN1 and strain 2002, respectively. V(V) was reduced to tetravalent vanadium V(IV) both intracellularly and extracellularly. Use of inhibitors and metabolomic analysis revealed enzyme catalysis and electron transfer pathways for V(V) reduction. Enzyme catalysis was identified by analyses of gene abundance, transcript abundance, and enzymatic activity. Electron transfer was verified through quantifying electron transporters, monitoring electron transport system activity, and performing cyclic voltammetry analysis. For strain BoFeN1, nitrite and nitrous oxide reductases played vital roles in V(V) reduction, together with cytochrome c (Cyt c) and nicotinamide adenine dinucleotide (NADH) mediated electron transfer. Differentially expressed riboflavin produced by strain BoFeN1 also promoted electron transfer. Strain 2002 mainly utilized periplasmic nitrate reductase to reduce V(V). Aquifer sediment bioaugmented with these strains enhanced V(V) reduction by 10.5%−51.1%. They well colonized and collaborated with indigenous microorganisms to reduce V(V) to V(IV). This study advances understanding of environmental biogeochemistry of vanadium and provides molecular insights into V(V) bio-reduction as a sustainable bioremediation strategy.
Bicellular Tight Junctions and Wound Healing Shi, Junhe; Barakat, May; Chen, Dandan ...
International journal of molecular sciences,
12/2018, Volume:
19, Issue:
12
Journal Article
Peer reviewed
Open access
Bicellular tight junctions (TJs) are intercellular junctions comprised of a variety of transmembrane proteins including occludin, claudins, and junctional adhesion molecules (JAMs) as well as ...intracellular scaffold proteins such as zonula occludens (ZOs). TJs are functional, intercellular structures that form a barrier between adjacent cells, which constantly seals and unseals to control the paracellular passage of molecules. They are primarily present in the epithelial and endothelial cells of all tissues and organs. In addition to their well-recognized roles in maintaining cell polarity and barrier functions, TJs are important regulators of signal transduction, which modulates cell proliferation, migration, and differentiation, as well as some components of the immune response and homeostasis. A vast breadth of research data is available on TJs, but little has been done to decipher their specific roles in wound healing, despite their primary distribution in epithelial and endothelial cells, which are essential contributors to the wound healing process. Some data exists to indicate that a better understanding of the functions and significance of TJs in healing wounds may prove crucial for future improvements in wound healing research and therapy. Specifically, recent studies demonstrate that occludin and claudin-1, which are two TJ component proteins, are present in migrating epithelial cells at the wound edge but are absent in chronic wounds. This indicates that functional TJs may be critical for effective wound healing. A tremendous amount of work is needed to investigate their roles in barrier function, re-epithelialization, angiogenesis, scar formation, and in the interactions between epithelial cells, endothelial cells, and immune cells both in the acute wound healing process and in non-healing wounds. A more thorough understanding of TJs in wound healing may shed new light on potential research targets and reveal novel strategies to enhance tissue regeneration and improve wound repair.
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