Plasminogen modulates formation of reactive oxygen species in human platelets

Reactive oxygen species (ROS) are considered to be important signalling molecules controlling many platelet functions. ROS production has been shown to be augmented by platelet activation, however, plasminogen (Pg) has not been studied in the context of modulating intraplatelet ROS levels. The aim of this study was to investigate the ability of different Pg forms to affect platelet metabolic activity/survival and intracellular ROS production in resting and activated platelets. Platelets isolated from donor plasma were pre-treated with Glu- or Lys-Pg (1.2 µM) and activated by thrombin (1.0 NIH unit/ml) or collagen (1.25 mg/ml). MTT assay was adapted to estimate total mitochondrial dehydrogenase activity, while intracellular ROS levels were monitored with the use of H2DCF-DA probe by flow cytometry. Lys-Pg was shown to slightly, but significantly, mitigate MTT reduction (P < 0.05 vs. control platelets). Two-fold elevation in metabolic activity of platelets stimulated by thrombin as compared to untreated cells was observed. However, this activation was less exhibi­ted in the case of platelets pre-incubated with either Glu- of Lys-Pg, with a predominant effect of Lys-Pg. Unlike thrombin, collagen treatment dramatically suppressed metabolic activity of platelets by 60% compared to control (P < 0.05). Glu- or Lys-Pg pre-incubation had no effects on the activity of collagen-stimulated platelets. Two subpopulations of platelets were observed with distinct characteristics of intracellular ROS formation. Elevated ROS production was demonstrated in these populations of both thrombin- and collagen-treated platelets. Pg (Lys-form to greater extent) enhanced intracellular ROS generation in thrombin-stimulated platelets. These findings suggest that augmented ROS generation within platelets pre-treated with Pg followed by their stimulation may result in down-regulation of their survival and functional activity. This study adds to our understanding one more possible mechanism of Pg impact on the platelet function

Structural and microstructural properties of Cd₁-xZnxTe films deposited by close spaced vacuum sublimation

The structural properties (microstresses, texture, lattice parameter, coherent scattering domains size) and chemical composition of Cd₁₋xZnxTe (CZT) films with variable zinc concentration were studied. Films were deposited on molybdenum coated glass substrates by close spaced vacuum sublimation method. Properties of samples were investigated by X-ray diffraction, energy dispersive spectroscopy, scanning electron microscopy. Zinc concentration in CdZnTe layers was determined by the EDS and from the lattice parameter, according to the literature data. Namely, it was determined that the CZT films had following Zn concentrations: x = 0.09, x = 0.24, x = 0.30

Structure, magnetic and thermodynamic properties of heterometallic ludwigites: Cu<inf>2</inf>GaBO<inf>5</inf> and Cu<inf>2</inf>AlBO<inf>5</inf>

© 2020 Elsevier B.V. We present an extensive study of the structural, magnetic and thermodynamic properties of high-quality monocrystals of two heterometallic oxyborates from the ludwigite family: Cu2GaBO5 and Cu2AlBO5 in the temperature range above 2 K. The distinctive feature of the investigated structures is the selective distribution of Cu and Ga/Al cations. The unit cell of Cu2GaBO5 and Cu2AlBO5 contains four nonequivalent crystallographic sites of metal ions. Two sites in the structure of Cu2GaBO5 are fully occupied by Cu atoms which form the quasi one-dimensional chains along the a-axis. For Cu2AlBO5 all sites are partially occupied by Al and Cu atoms. The joint analysis of low-temperature data on magnetic susceptibility and magnetic contribution to the specific heat showed that Cu2AlBO5 and Cu2GaBO5 exhibit an antiferromagnetic transition at TN=2.4 and 4.1 K, respectively. The magnetic response below TN can be represented as the sum of two contributions: the ordered component and the paramagnetic contribution from defects of the same relative weight. It is shown that the external magnetic field above 2.5 T and 2.8 T for Cu2GaBO5 and Cu2AlBO5, respectively, leads to a broadening of the magnetic phase transition indicating suppression of the long-range antiferromagnetic order