Essentials
Platelet microparticles play a major role in pathologies, including hemostasis and thrombosis.
Platelet microparticles have been analyzed and classified based on their ultrastructure.
The ...structure and intracellular origin of microparticles depend on the cell‐activating stimulus.
Thrombin‐treated platelets fall apart and form microparticles that contain cellular organelles.
Summary
Background
Platelet‐derived microparticles comprise the major population of circulating blood microparticles that play an important role in hemostasis and thrombosis. Despite numerous studies on the (patho)physiological roles of platelet‐derived microparticles, mechanisms of their formation and structural details remain largely unknown.
Objectives
Here we studied the formation, ultrastructure and composition of platelet‐derived microparticles from isolated human platelets, either quiescent or stimulated with one of the following activators: arachidonic acid, ADP, collagen, thrombin or calcium ionophore A23187.
Methods
Using flow cytometry, transmission and scanning electron microscopy, we analyzed the intracellular origin, structural diversity and size distributions of the subcellular particles released from platelets.
Results
The structure, dimensions and intracellular origin of microparticles depend on the cell‐activating stimulus. The main structural groups include a vesicle surrounded by one thin membrane or multivesicular structures. Thrombin, unlike other stimuli, induced formation of microparticles not only from the platelet plasma membrane and cytoplasm but also from intracellular structures. A fraction of these vesicular particles having an intracellular origin contained organelles, such as mitochondria, glycogen granules and vacuoles. The size of platelet‐derived microparticles depended on the nature of the cell‐activating stimulus.
Conclusion
The results obtained provide a structural basis for the qualitative differences of various platelet activators, for specific physiological and pathological effects of microparticles, and for development of advanced assays.
Molecular and crystal structures of the following three cyclic compounds with condensed naphthyl fragments are studied: crystals of 1H,5H-naphtho1,8-ef1,3dithiocine and ...1H,5H-naphtho1,8-ef1,2,3trithiocine, and an isomer of the latter compound with a seven-membered heterocycle 1,5-dihydronaphtho2,3-e1,2,3trithiepine. The crystals of the first two compounds are isostructural. It is shown that eight-membered heterocycles and the seven-membered ring in the sulfur-containing molecules occur in
boat
and
chair
conformations, respectively, in contrast to acetals of a similar structure. The crystal structure of the studied compounds is determined by dispersion Van der Waals interactions.
The reaction of organonickel complexes of the type NiBr(aryl)(bpy), where aryl = 2,4,6-trimethylphenyl (Mes,
1
), 2,3,4,5,6-pentamethylphenyl (Pmp,
2
), 2,4,6-triisopropylphenyl (Tipp,
3
), bpy = ...2,2′-bipyridine, with sodium bis(diglyme) 3,4,5-triphenyl-1,2-diphosphacyclopentadienide (sodium 1,2-diphospholide, SDP) leads to unknown 1-aryl-3,4,5-triphenyl-1,2-diphosphacyclopenta-2,4-dienes (1-aryl-1,2-diphospholes, ADPs)
4
-
6
by the organic group transfer from organonickel complexes to 3,4,5-triphenyl-1,2-diphospholide (DP). The mechanism of the reaction was explored by experimental (ESI-MS, ESR spectroscopy) and quantum-chemical (DFT) methods suggesting the formation of intermediate nickel(
ii
) phospholide complexes capable of reductive elimination leading to the desired organophosphorus products and nickel nanoparticles (NiNPs). The solid-state luminescence of the obtained 1-aryl-3,4,5-triphenyl-1,2-diphospholes
4-
6
was investigated.
The reaction of NiBr(aryl)(bpy) organonickel complexes with sodium 1,2-diphospholide leads to unknown 1-aryl-1,2-diphospholes by aryl group transfer.
The paper presents a general approach to geometric modelling of torse surfaces in BN-calculus, based on the definition of the torse as the geometric location of tangents to its edge of return. In ...this paper, a method for determining the curves - edges of the return of the torse surface, using the geometric properties of the point definition of the curve in plane and spatial simplices, is proposed in general form. Examples of constructing geometric models of torse surfaces, for which algebraic and transcendental spatial curves were used as the return edge, are given.
A fast and sensitive resonant Schottky pick-up for heavy ion storage rings Nolden, F.; Hülsmann, P.; Litvinov, Yu.A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2011, Letnik:
659, Številka:
1
Journal Article
Recenzirano
A resonant pick-up for the detection of heavy ion Schottky noise was built into the ESR storage ring at GSI. A similar device will be installed at the cooler storage ring CSRe at IMP. Its purpose is ...a significant enhancement of the signal to noise ratio of Schottky spectra. A particular application of the new system is the measurement of circulating single ions. The resonator is based on a pillbox design. It is operated at air pressure, and is electromagnetically coupled to the vacuum tube of the storage ring via a cylinder-shaped ceramic gap. The resonant frequency can be changed by inserting plunger pistons. The resonator can easily be decoupled from the storage ring, if high beam impedances become a problem. The article describes the construction, electromagnetic properties of the pick-up as well as first experiments with heavy ion beams.
Gamma-ray spectrometry on ITER can provide information both on confined fusion alpha particles for optimization of plasma heating and runaway electrons, which is important for safe reactor ...operations. For the purpose of deconvolution of gamma-ray spectra recorded in fusion plasma experiments the DeGaSum code has been developed. The code can be applied for processing of both spectra of monoenergetic gamma rays, which are born in nuclear reactions produced by alpha particles and other fast ions, and continuous bremsstrahlung spectra generated by runaway electrons in the MeV range in the plasma and reactor structure materials. Gamma-ray spectrometer response functions and bremsstrahlung spectra generated by electrons in the MeV energy range are calculated and used in the DeGaSum code. The deconvolution of the discrete spectra allows the identification of nuclear reactions, which give rise to gamma rays, and the calculation of their intensities. By applying the code for continuous hard x-ray spectra, the runaway electron energy distribution can be inferred. It can provide the maximal energy of runaway electrons with accuracy, which satisfies the ITER project requirements. The code has been used for processing of spectra recorded in JET experiments. An application of the deconvolution technique for gamma-ray emission measurements on ITER is discussed.
Prolonged (~4 years) keeping of mixtures of phosphorus trichloride or tribromide with methyl triflate in dark at 20–25°C has led to the formation of crystalline methyltrichloro- and ...methyltribromophosphonium triflates with a content of 10–11% in the reaction mixture and yield of 5–6%. Structure of the triflates has been elucidated by means of X-ray diffraction analysis.
A new convenient method for the preparation of dichlorodinitro-2,1,3-oxadiazole-1-oxide (dichlorodinitrobenzofuroxan) has been developed. Composition and structure of the prepared ...dichlorodinitrobenzofuroxan have been elucidated by a set of chemical, physical, and physico-chemical methods and also confirmed for the first time via single crystal X-ray diffraction analysis. Thermal stability of the compound has been investigated using a method of combined thermogravimetry and differential scanning calorimetry.
Molecular and crystal structures of five substituted urea derivatives with bulky adamantyl fragments in their substituents are considered. It is shown that the crystals of these compounds are formed ...by a system of intermolecular hydrogen bonds. The molecules without proton-donor groups in the lateral substituents form a linear system of N–H⋯O hydrogen bonds involving only the amide functional group, while the urea molecules containing proton-donor groups or the crystal solvates with proton-donor solvate molecules exhibit more complex motifs of hydrogen bonds.
We explore the possibility of using measurements of the gravitational redshift effect as a means to constrain wave dark matter—a class of models in which the dark matter is accounted for by light ...scalar particles that behave like classical waves. We construct a mathematical framework that is appropriate for clock comparison experiments with remote clocks and can be used to determine the values of the coupling constants of such dark matter with particles of the Standard Model. Using this framework, we consider an experiment to detect dark matter of the Galactic halo using two satellites equipped with accurate and stable atomic clocks and placed into elliptical heliocentric orbits. We demonstrate that, in most cases, the accuracy of this experiment turns out to be not better than that of ground-based experiments with colocated clocks. The limitation of the accuracy of the space-based experiment is found to be due to the non-relativistic Doppler compensation system, required when using moving clocks, which decreases the amplitude of the useful signal. Possible solutions to this problem are discussed.
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