Analysis of the Morphology of Monocytes and Lymphocytes from COVID-19 Patients Using Low-Voltage Scanning Electronic Microscopy.

Severe course of COVID-19 is largely determined by hyperactivation of the immune system, or cytokine storm, in which immune cells (lymphocytes, monocytes, etc.) play a major role. Using low-voltage scanning electron microscopy, we studied the morphology of lymphocytes and monocytes during cytokine storm. Monocytes and lymphocytes were isolated by fluorescence sorting from the blood of healthy volunteers (n=6) and patients with COVID-19 (n=5) during cytokine storm (IL-6>23 ng/ml, smear positive for SARS-CoV-2). For each patient, 11-32 individual cells were analyzed at magnification of 18-32,000 times. Measurements showed that monocyte size was increased during cytokine storm (p=0.0001).

Hydrogen passivation of the n-GaN nanowire/p-Si heterointerface.

The influence of hydrogen plasma treatment on the electrical and optical properties of vertical GaN nanowire (NW)/Si heterostructures synthesized via plasma assisted molecular beam epitaxy is studied. The effect of the treatment is thoroughly studied via variation of the passivation duration. Photoluminescence investigation demonstrates that the passivation affects the doping of the GaN NWs. The samples were processed as photodiodes with a top transparent electrode to obtain detailed information about the n-GaN NWs/p-Si heterointerface under illumination. The electron beam induced current measurements demonstrated the absence of potential barriers between the active parts of the diode and the contacts, indicating ohmic behavior of the latter. I-V characteristics obtained in the dark and under illumination show that hydrogen can effectively passivate the recombination centers at the GaN NWs/Si heterointerface. The optimum passivation duration, providing improved electrical properties, is found to be 10 min within the studied passivation regimes. It is demonstrated that longer treatment causes degradation of the electrical properties. The discovered phenomenon is discussed in detail.

Heterogeneous nucleation of catalyst-free InAs nanowires on silicon.

We report on the heterogeneous nucleation of catalyst-free InAs nanowires on Si(111) substrates by chemical beam epitaxy. We show that nanowire nucleation is enhanced by sputtering the silicon substrate with energetic particles. We argue that particle bombardment introduces lattice defects on the silicon surface that serve as preferential nucleation sites. The formation of these nucleation sites can be controlled by the sputtering parameters, allowing the control of nanowire density in a wide range. Nanowire nucleation is accompanied by unwanted parasitic islands, but careful choice of annealing and growth temperature allows us to strongly reduce the relative density of these islands and to realize samples with high nanowire yield.

EXTRACELLULAR VESICLES FROM BLOOD PLASMA STUDIED BY LOW VOLTAGE SCANNING ELECTRON MICROSCOPY.

Extracellular vesicles are subspherical membranous structures secreted by cells and enriched with different types of biological molecules. The number and the molecular content of these structures depend on pathological conditions and the physiological state of the organism. Extracellular vesicles play an important role in intercellular communication and represent potential disease biomarkers. However, mechanisms of formation, functions and morphological characteristics of extracellular vesicles are still studied insufficiently. Low voltage scanning electron microscopy is a promising method to investigate extracellular vesicles, since it does not require conductive coating and therefore enables a high-resolution visualization of morphological details of nanosized objects. This paper presents the results of low voltage scanning electron microscopy study of morphology and size of objects from blood plasma fractions.

Soluble Fas antigen in the serum of women with oral lichen planus.

Enzyme immunoassay showed that soluble Fas antigen is significantly more often detected in the serum of patients with oral lichen planus (72.5%) and oral squamous-cell cancer (75%) than in healthy postmenopausal women (36%). The level of soluble Fas antigen was significantly higher in patients with squamous-cell cancer and erosive ulcerative and exudative hyperemic lichen planus than in healthy women.

[Reversible disorder of polyamine and DNA synthesis in regenerating rat liver]. / Obratimoe narushenie sinteza poliaminov i DNK v regeneriruiushchei pecheni krysy.

A single injection of diaminohexane (DAH) causes an abrupt but reversible decrease in the putrescine concentration in the regenerating rat liver. Under experimental conditions hepatic spermidine and spermin content remains invariable while the synthesis of these compounds temporarily decreases. Incorporation of the radioactive precursors into proteins and RNA of the regenerating liver does not essentially change after DAH injection. However, DNA synthesis is sharply reduced. Incorporation of 3H-thymidine into DNA directly correlates with the putrescine concentration and spermidine synthesis. The results suggest that putrescine is essential for maintenance of normal DNA replication in the regenerating rat liver.

[Spinal cord hypothermia in neurosurgical practice]. / Gipotermiia spinnogo mozga v neirokhirurgicheskoi praktike.

Spinal cord hypothermia was conducted in 113 patients. It led to a decrease of bleeding from the tissues during the operation, reduced edema of the spinal cord, diminished spasticity of muscles, improved motor function of the affected limbs, and alleviation of the pain syndrome. Hypothermia of the spinal cord also caused changes in motoneuron excitability and circulation, both local and general, and shifts in body thermoregulation.