Biogenic Synthesis and Characterization of Antioxidant and Antimicrobial Silver Nanoparticles Using Flower Extract of Couroupita guianensis Aubl.

Couroupita guianensis Aubl. is an important medicinal tree. This tree is rich in various phytochemicals, and is therefore used as a potent antioxidant and antibacterial agent. This plant is also used for the treatment of various diseases. Here, we have improved its medicinal usage with the biosynthesis of silver nanoparticles (AgNPs) using Couroupita guianensis Aubl. flower extract as a reducing and capping agent. The biosynthesis of the AgNPs reaction was carried out using 1 mM of silver nitrate and flower extract. The effect of the temperature on the biosynthesis of AgNPs was premeditated by room temperature (25 °C) and 60 °C. The continuous stirring of the reaction mixture at room temperature for approximately one hour resulted in the successful formation of AgNPs. A development of a yellowish brown color confirmed the formation of AgNPs. The efficacious development of AgNPs was confirmed by the characteristic peaks of UV–Vis, X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy spectra. The biosynthesized AgNPs exhibited significant free radical scavenging activity through a DPPH antioxidant assay. These AgNPs also showed potent antibacterial activity against many pathogenic bacterial species. The results of molecular dynamics simulations also proved the average size of NPs and antibacterial potential of the flower extract. The observations clearly recommended that the green biosynthesized AgNPs can serve as effective antioxidants and antibacterial agents over the plant extract.     

Green Synthesis of Zinc Oxide Nanoparticles (ZnO-NPs) by Pseudomonas aeruginosa and Their Activity against Pathogenic Microbes and Common House Mosquito,Culex pipiens

The synthesis of nanoparticles by green approaches is gaining unique importance due to its low cost, biocompatibility, high productivity, and purity, and being environmentally friendly. Herein, biomass filtrate of Pseudomonas aeruginosa isolated from mangrove rhizosphere sediment was used for the biosynthesis of zinc oxide nanoparticles (ZnO-NPs). The bacterial isolate was identified based on morphological, physiological, and 16S rRNA. The bio-fabricated ZnO-NPs were characterized using color change, UV-visible spectroscopy, FT-IR, TEM, and XRD analyses. In the current study, spherical and crystalline nature ZnO-NPs were successfully formed at a maximum SPR (surface plasmon resonance) of 380 nm. The bioactivities of fabricated ZnO-NPs including antibacterial, anti-candida, and larvicidal efficacy were investigated. Data analysis showed that these bioactivities were concentration-dependent. The green-synthesized ZnO-NPs exhibited high efficacy against pathogenic Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), and unicellular fungi (Candida albicans) with inhibition zones of (12.33 ± 0.9 and 29.3 ± 0.3 mm), (19.3 ± 0.3 and 11.7 ± 0.3 mm), and (22.3 ± 0.3 mm), respectively, at 200 ppm. The MIC value was detected as 50 ppm for E. coli, B. subtilis, and C. albicans, and 200 ppm for S. aureus and P. aeruginosa with zones of inhibition ranging between 11.7 ± 0.3–14.6 ± 0.6 mm. Moreover, the biosynthesized ZnO-NPs showed high mortality for Culex pipiens with percentages of 100 ± 0.0% at 200 ppm after 24 h as compared with zinc acetate (44.3 ± 3.3%) at the same concentration and the same time.     

Impact of Elevated Temperatures on Strength Properties and Microstructure of Calcium Sulfoaluminate Paste

This article is motivated by civil fire safety. Fire-prevention engineering demands a wide range of information about building materials including alternative cements, for instance CSA-cement. Because of exposure of the cement-base material to a high temperature, its strength properties deteriorate due to dehydration connected with phase and microstructure changes. Previous research indicated that the main endothermic reaction of CSA-based composite, dehydration of ettringite, might be used as a cooling system for a metal structure during fire-load. This article examines visual assessment, microstructure, density, as well as flexural and compressive strength parameters of CSA-based composite after isothermal heating at temperatures from 23 °C to 800 °C. The results of SEM/EDS investigations showed that the calcium sulfoaluminate paste may start partially re-sintering above 600 °C. Mechanical tests revealed significant reduction of strength parameters but residual compressive strength was maintained in the whole temperature range e.g., 8 MPa at 800 °C. Additionally, visual assessment of the specimens indicated that it might be possible to predict the material temperature heating based on the specific surface color. These findings add to the evidence of general knowledge about CSA hydrates.     

Green Synthesis of Silver-Decorated Magnetic Particles for Efficient and Reusable Antimicrobial Activity

Metal and metal hybrid nanostructures have shown tremendous application in the biomedical and catalytic fields because of their plasmonic and catalytic properties. Here, a green and clean method was employed for the synthesis of silver nanoparticle (Ag NP)-SiO₂-Fe₂O₃ hybrid microstructures, and biomolecules from green tea extracts were used for constructing the hybrid structures. The SiO₂-Fe₂O₃ structures were synthesized using an ethanolic green tea leaf extract to form Bio-SiO₂-Fe₂O₃ (BSiO₂-Fe₂O₃) structures. Biochemical studies demonstrated the presence of green tea biomolecules in the BSiO₂ layer. Reduction of the silver ions was performed by a BSiO₂ layer to form Ag NPs of 5–10 nm in diameter in and on the BSiO₂-Fe₂O₃ microstructure. The reduction process was observed within 600 s, which is faster than that reported elsewhere. The antimicrobial activity of the Ag-BSiO₂-Fe₂O₃ hybrid structure was demonstrated against Staphylococcus aureus and Escherichia coli, and the nanostructures were further visualized using confocal laser scanning microscopy (CLSM). The magnetic properties of the Ag-BSiO₂-Fe₂O₃ hybrid structure were used for studying reusable antimicrobial activity. Thus, in this study, we provide a novel green route for the construction of a biomolecule-entrapped SiO₂-Fe₂O₃ structure and their use for the ultra-fast formation of Ag NPs to form antimicrobial active multifunctional hybrid structures.     

Early synaptogenesis in vitro: Role of axon target distance

In contrast to some previous reports suggesting a delay in synapse formation in vitro, we found that under ideal conditions, most hippocampal and hypothalamic rat neurons were synaptically coupled after 3 or 4 days in vitro. Synaptophysin immunocytochemistry revealed strongly stained presynaptic boutons by 3 days in vitro. Studies with time-lapse laser confocal imaging of FM-143 revealed that axonal boutons were recycling their synaptic vesicles, an indication of synapse formation, as early as 3 days after plating. To test the hypothesis that neurite outgrowth was enhanced in high-density cultures, thereby increasing the probability of synapse formation, neurons were transfected with the jellyfish green fluorescent protein (GFP) gene. After 2 days in high-density cultures, green fluorescent neurites were about three times longer than in sister neurons plated in low-density cultures. Even in single dishes, GFP-transfected cells in contact with other neurons had neurites that were at least three times longer and grew faster than more isolated cells. Neurons grew longer neurites (+51%) when growing on surface membranes of heat-killed neurons than on polylysine, underlining the importance of plasma membrane contact. Calcium imaging with fura-2 and whole cell recording showed that both GABA and glutamate presynaptic release occurred after 3 or 4 days in vitro in high-density cultures but was absent in low-density cultures at this time. Together, these morphological, cytochemical, and physiological data suggest that the distance an axon must grow to find a postsynaptic partner plays a substantial role in the timing of synapse formation. Although other factors in vitro may also play a role, the distance to a postsynaptic target, which defines the interval during which an axon grows to its target, can probably account for much of the difference in timing of synapse formation previously reported in vitro. A short intercell distance may increase the concentration of limited amounts of trophic factors available to a nearby cell, and once contact is made, a neuronal membrane provides a superior substrate for neuritic elongation. J. Comp. Neurol. 399:541–560, 1998. © 1998 Wiley-Liss, Inc.     

Intra-Host SARS-CoV-2 Evolution in the Gut of Mucosally-Infected Chlorocebus aethiops (African Green Monkeys)

In recent months, several SARS-CoV-2 variants have emerged that enhance transmissibility and escape host humoral immunity. Hence, the tracking of viral evolutionary trajectories is clearly of great importance. Little is known about SARS-CoV-2 evolution in nonhuman primate models used to test vaccines and therapies and to model human disease. Viral RNA was sequenced from rectal swabs from Chlorocebus aethiops (African green monkeys) after experimental respiratory SARS-CoV-2 infection. Two distinct patterns of viral evolution were identified that were shared between all collected samples. First, mutations in the furin cleavage site that were initially present in the virus as a consequence of VeroE6 cell culture adaptation were not detected in viral RNA recovered in rectal swabs, confirming the necessity of this motif for viral infection in vivo. Three amino acid changes were also identified; ORF 1a S2103F, and spike D215G and H655Y, which were detected in rectal swabs from all sampled animals. These findings are demonstrative of intra-host SARS-CoV-2 evolution and may identify a host-adapted variant of SARS-CoV-2 that would be useful in future primate models involving SARS-CoV-2 infection.     

The influence of green coffee bean extract supplementation on blood glucose levels: A systematic review and dose–response meta‐analysis of randomized controlled trials

Studies regarding the influence of green coffee extract (GCE) on blood glucose levels are conflicting. Thus, we sought to conduct a meta‐analysis and systematic review of all available randomized controlled trials (RCTs) to quantify the effects of GCE and CGA intervention on blood glucose and insulin levels. We performed systematic online searches in Scopus, Web of science, and PubMed databases, from inception to July 2019. Data were combined analyzed using a random effects model (Der Simonian‐Laird method) and reported as weighted mean differences (WMD). Ten trials reported the influences of GCE on FBS and insulin and were subsequently entered into the meta‐analysis. Combined results highlighted that FBS was significantly altered after GCE consumption (WMD: ?1.791 mg/dl, 95% CI ?3.404, ?0.177), with no significant heterogeneity among the studies (I² = 35.0%, p = .128). However, overall results demonstrated that GCE administration did not result in any significant alteration in insulin levels (WMD: ?0.925 μU/ml, 95% CI:?1.915, 0.064), with significant heterogeneity found across studies (I² = 87.9%). In sub‐group analysis, insulin levels were significantly reduced when GCE was supplemented in dosages of ≥400 mg/day (WMD:?1.942 mg/dl, 95% CI:?1.184, ?0.975; I² = 0.0%). The results of present study support the use of GCE for the enhancement of blood glucose, while subgroup analysis highlighted significant improvements in insulin levels when GCE is supplemented in doses ≥400 mg/day.     

膜联蛋白A5绿色荧光蛋白重组质粒的构建及其在宫颈癌细胞系Hela细胞中的表达

目的：构建在哺乳动物细胞中表达的膜联蛋白A5(anxA5)的重组质粒,并在真核细胞中表达。方法：用PCR方法从pJLA503-anxA5质粒中扩增anx A5的基因序列,引入酶切位点XhoⅠ和Bam HⅠ。将真核表达质粒pEGFP-N1和anxA5的PCR产物经双酶切后用T4连接酶连接,并经鉴定序列正确后,用磷酸钙共沉淀法稳定转染Hela细胞,荧光显微镜下观察;免疫细胞化学染色观察anxA5在Hela细胞的表达。结果：重组质粒鉴定正确,稳定转染Hela细胞,在荧光显微镜下可见绿色荧光,免疫细胞化学染色可见anxA5表达。结论：成功构建了pEGFP-anxA5重组质粒,并能在宫颈癌细胞系Hela细胞中表达,为研究anxA5的功能及其在细胞系中的作用奠定了基础。