Magnesium acetyltaurate prevents retinal damage and visual impairment in rats through suppression of NMDA-induced upregulation of NF-κB,p53 and AP-1(c-Jun/c-Fos)

Magnesium acetyltaurate(MgAT)has been shown to have a protective effect against N-methyl-D-aspartate(NMDA)-induced retinal cell apoptosis.The current study investigated the involvement of nuclear factor kappa-B(NF-κB),p53 and AP-1 family members(c-Jun/c-Fos)in neuroprotection by MgAT against NMDA-induced retinal damage.In this study,Sprague-Dawley rats were randomized to undergo intravitreal injection of vehicle,NMDA or MgAT as pre-treatment to NMDA.Seven days after injections,retinal ganglion cells survival was detected using retrograde labelling with fluorogold and BRN3A immunostaining.Functional outcome of retinal damage was assessed using electroretinography,and the mechanisms underlying antiapoptotic effect of MgAT were investigated through assessment of retinal gene expression of NF-κB,p53 and AP-1 family members(c-Jun/c-Fos)using reverse transcription-polymerase chain reaction.Retinal phospho-NF-κB,phospho-p53 and AP-1 levels were evaluated using western blot assay.Rat visual functions were evaluated using visual object recognition tests.Both retrograde labelling and BRN3A immunostaining revealed a significant increase in the number of retinal ganglion cells in rats receiving intravitreal injection of MgAT compared with the rats receiving intravitreal injection of NMDA.Electroretinography indicated that pre-treatment with MgAT partially preserved the functional activity of NMDA-exposed retinas.MgAT abolished NMDA-induced increase of retinal phospho-NF-κB,phospho-p53 and AP-1 expression and suppressed NMDA-induced transcriptional activity of NF-κB,p53 and AP-1 family members(c-Jun/c-Fos).Visual object recognition tests showed that MgAT reduced difficulties in recognizing the visual cues(i.e.objects with different shapes)after NMDA exposure,suggesting that visual functions of rats were relatively preserved by pre-treatment with MgAT.In conclusion,pre-treatment with MgAT prevents NMDA induced retinal injury by inhibiting NMDA-induced neuronal apoptosis via downregulation of transcriptional activity of NF-κB,p53 and AP-1-mediated c-Jun/c-Fos.The experiments were approved by the Animal Ethics Committee of Universiti Teknologi MARA(UiTM),Malaysia,UiTM CARE No 118/2015 on December 4,2015 and UiTM CARE No 220/7/2017 on December 8,2017 and Ethics Committee of Belgorod State National Research University,Russia,No 02/20 on January 10,2020.

Preparation of crystalline Mg(OH)2 nanopowder from serpentinite mineral

In this paper we describe a route to produce crystalline Mg(OH)2 nanopowders from serpentinite ore distributed in the Halilovskiy array(Russia, Orenburg region). An efficient extraction route consisting of treatment on serpentinite in 40% HNO_3 at 80 °C followed by NH_4OH titration for Mg(OH)_2 precipitation was demonstrated. In this study, crystalline Mg(OH)2 nanopowders have been synthesized by solvothermal reaction method using(Mg(NO_3)_2á6H_2O) which were obtained from serpentinite, NH4 OH as a precipitator, and hydroxyethylated nonylphenol as surface-active substance. Microstructure and phase composition of samples were investigated employing scanning electron microscopy(SEM) and transmission electron microscopy(TEM), X-ray phase analysis(XRD), and inductively coupled plasma optical emission spectroscopy(ICP-OES). XRD reveals that Mg(OH)2 nanopowder with high purity has the brucite structure. It was found that crystalline Mg(OH)_2 nanopowders exclusively consist of lamellar-like structures and the sizes of Mg(OH)_2 are 30–265 nm length or width.

Effects of mechanical activation on the structural changes and microstructural characteristics of the components of ferruginous quartzite beneficiation tailings

The effects of mechanical activation in a planetary mill on the structural changes and microstructural characteristics of the components of ferruginous quartzite beneficiation tailings generated by wet magnetic separation process were studied using X-ray and laser diffraction methods. The results revealed the relationship between variations in the mean particle size of activated powders and the milling time. The crystallite size, microstrain, lattice parameters and unit cell volumes were determined for different milling times in powder samples of quartz, hematite, dolomite, and magnetite from the beneficiation tailings. The main trends in the variation of the crystallite size of quartz, hematite, dolomite, and magnetite as a function mean particle size of powder samples were revealed. Changes in the particle shape as a function of the activation time was also investigated.

Effect of multiaxial deformation on structure, mechanical properties, and corrosion resistance of a Mg-Ca alloy

This article provides a report on the effect of multiaxial deformation(MAD) on the structure, texture, mechanical characteristics, and corrosion resistance of the Mg-0.8(wt.)% Ca alloy. MAD was carried out on the alloy in the as-cast and the annealed states in multiple passes, with a stepwise decrease in the deformation temperature from 450 to 250 ℃ in 50 ℃ steps. The cumulative true strain at the end of the process was 22.5. In the case of the as-cast alloy, this resulted in a refined microstructure characterized by an average grain size of 2.7 μm and a fraction of high-angle boundaries(HABs) of 57.6%. The corresponding values for the annealed alloy were 2.1 μm and 68.2%. The predominant mechanism of structure formation was associated with discontinuous and continuous dynamic recrystallization acting in concert. MAD was also shown to lead to the formation of a rather sharp prismatic texture in the as-cast alloy, whilst in the case of the annealed one the texture was weakened. A displacement of the basal poles {00.4} from the periphery to the center of a pole figure was observed. These changes in the microstructure and texture gave rise to a significant improvement of the mechanical characteristics of the alloy. This included an increase of the ultimate tensile strength reaching 308 MPa for annealed material and 264 MPa for the as-cast one in conjunction with a twofold increase in ductility. A further important result of the MAD processing was a reduction of the rate of electrochemical corrosion, as indicated by a significant decrease in the corrosion current density in both microstructural states of the alloy studied.