Publications by authors named "Penkov N"

Background: McKittrick-Wheelock syndrome is an uncommon and severe disorder caused by large hypersecretory tumors located in the distal colorectal area. Excessive secretion from adenomas is an unusual clinical manifestation that leads to severe electrolyte and fluid depletion, subsequently resulting in kidney injury. Successful treatment relies on quick and cooperative decision-making for timely intervention.

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Two novel membranes based on collagen and two polyphenols, taxifolin pentaglutarate (TfG5) and a conjugate of taxifolin with glyoxylic acid (DfTf), were prepared. Fourier transform infrared spectroscopy examination confirmed the preservation of the triple helical structure of collagen. A scanning electron microscopy study showed that both materials had a porous structure.

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Article Synopsis
  • Necrotizing pancreatitis (NP) is a serious condition with high risks, and its treatment has shifted from open surgery to less invasive methods like percutaneous catheter drainage (PCD).
  • A 71-year-old male with acute abdominal pain experienced worsening symptoms due to sepsis, leading to the discovery of large fluid collections around the pancreas, which were resolved with PCD.
  • Studies, including the PANTER trial, have shown that PCD is safer and more effective than traditional surgery for infected necrotizing pancreatitis, resulting in fewer complications and lower healthcare costs.
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The advancement of experimental methods has provided new information about the structure and structural fluctuations of water. Despite the appearance of numerous models, which aim to describe a wide range of thermodynamic and electrical characteristics of water, there is a deficit in systemic understanding of structuring in aqueous solutions. A particular challenge is the fact that even pure water is a heterogeneous, multicomponent system composed of molecular and supramolecular structures.

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Titin is a multidomain protein of striated and smooth muscles of vertebrates. The protein consists of repeating immunoglobulin-like (Ig) and fibronectin-like (FnIII) domains, which are β-sandwiches with a predominant β-structure, and also contains disordered regions. In this work, the methods of atomic force microscopy (AFM), X-ray diffraction, and Fourier transform infrared spectroscopy were used to study the morphology and structure of aggregates of rabbit skeletal muscle titin obtained in two different solutions: 0.

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In this work, the terahertz time-domain spectroscopy method analyzed solutions of bovine serum albumin (BSA) in two high concentrations (50 and 334 mg/mL) at three pH values (2.5, 6.5, 8.

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This paper describes an approach based on the method of terahertz time-domain spectroscopy, which allows the analysis of dynamical hydration shells of proteins with a thickness of 1-2 nm. Using the example of bovine serum albumin in three conformations, it is shown that the hydration shells of the protein are characterized by increased binding of water molecules in the primary hydration layers, and in more distant areas of hydration, on the contrary, the water structure is somewhat destroyed. The fraction of free or weakly bound molecules, usually observed in the structure of liquid water in hydration shells, become more numerous but its average binding is greater than in undisturbed water.

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The investigation into the behavior of ficin, bromelain, papain under thermal conditions holds both theoretical and practical significance. The production processes of medicines and cosmetics often involve exposure to high temperatures, particularly during the final product sterilization phase. Hence, it's crucial to identify the "critical" temperatures for each component within the mixture for effective technological regulation.

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The hydration of biomolecules is one of the fundamental processes underlying the construction of living matter. The formation of the native conformation of most biomolecules is possible only in an aqueous environment. At the same time, not only water affects the structure of biomolecules, but also biomolecules affect the structure of water, forming hydration shells.

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The effect of hyperglycemia on the morphology of individual mitochondria and the state of the mitochondrial network in primary mouse lung microvascular endotheliocytes and human dermal fibroblasts has been investigated. The cells were exposed to high (30 mM) and low (5.5 mM) glucose concentrations for 36 h.

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Turpentine oil, owing to the presence of 7-50 terpenes, has analgesic, anti-inflammatory, immunomodulatory, antibacterial, anticoagulant, antioxidant, and antitumor properties, which are important for medical emulsion preparation. The addition of turpentine oil to squalene emulsions can increase their effectiveness, thereby reducing the concentration of expensive and possibly deficient squalene, and increasing its stability and shelf life. In this study, squalene emulsions were obtained by adding various concentrations of turpentine oil via high-pressure homogenization, and the safety and effectiveness of the obtained emulsions were studied in vitro and in vivo.

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A giant multidomain protein of striated and smooth vertebrate muscles, titin, consists of tandems of immunoglobulin (Ig)- and fibronectin type III (FnIII)-like domains representing β-sandwiches, as well as of disordered segments. Chicken smooth muscles express several titin isoforms of ~500-1500 kDa. Using various structural-analysis methods, we investigated in vitro nonspecific amyloid aggregation of the high-molecular-weight isoform of chicken smooth-muscle titin (SMT, ~1500 kDa).

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The present study evaluates the cytotoxicity of a previously synthesized conjugate of betulinic acid (BA) with the penetrating cation F16 on breast adenocarcinoma (MCF-7) and human fibroblast (HF) cell lines, and also shows the mechanism underlying its membranotropic action. It was confirmed that the conjugate exhibits higher cytotoxicity compared to native BA at low doses also blocking the proliferation of both cell lines and causing cell cycle arrest in the G/G phase. We show that the conjugate indeed has a high potential for accumulation in mitochondria, being visualized in these organelles, which is most pronounced in cancer cells.

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Effect of alisporivir (a mitochondrial permeability transition pore inhibitor) on the development of mitochondrial dysfunction under hyperglycemic conditions in the primary culture of mouse lung endothelial cells was investigated in this work. We demonstrated that hyperglycemia (30 mM glucose for 24 h) leads to the decrease in viability of the pulmonary endotheliocytes, causes mitochondrial dysfunction manifested by the drop in membrane potential and increase in superoxide anion generation as well as facilitates opening of the mitochondrial permeability transition pore (MPT pore). Incubation of endothelial cells with 5 µM alisporivir under hyperglycemic conditions leads to the increase in cell viability, restoration of the membrane potential level and of the MPT pore opening activity to control values.

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Self-assembly of organic ions in aqueous solutions is a hot topic at the present time, and substances that are well-soluble in water are usually studied. In this work, aqueous solutions of sodium diclofenac are investigated, which, like most medicinal compounds, is poorly soluble in water. Classical MD modeling of an aqueous solution of diclofenac sodium showed equilibrium between the hydrated anion and the hydrated dimer of the diclofenac anion.

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Terahertz spectroscopy allows for the analysis of vibrations corresponding to the large-scale structural movements and collective dynamics of hydrogen-bonded water molecules. Previously, differences had been detected in the emission spectra of interferon-gamma (IFNγ) solutions surrounded by extremely diluted solutions of either IFNγ or antibodies to IFNγ without direct contact compared to a control. Here we aimed to analyse the structural properties of water in a sample of an aqueous solution of IFNγ via terahertz time-domain spectroscopy (THz-TDS).

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Despite more than a century of research on the hydration of biomolecules, the hydration of carbohydrates is insufficiently studied. An approach to studying dynamic hydration shells of carbohydrates in aqueous solutions based on terahertz time-domain spectroscopy assay is developed in the current work. Monosaccharides (glucose, galactose, galacturonic acid) and polysaccharides (dextran, amylopectin, polygalacturonic acid) solutions were studied.

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Here, we found that functionally active mitochondria isolated from the brain of NMRI donor mice and administrated intranasally to recipient mice penetrated the brain structures in a dose-dependent manner. The injected mitochondria labeled with the MitoTracker Red localized in different brain regions, including the neocortex and hippocampus, which are responsible for memory and affected by degeneration in patients with Alzheimer's disease. In behavioral experiments, intranasal microinjections of brain mitochondria of native NMRI mice improved spatial memory in the olfactory bulbectomized (OBX) mice with Alzheimer's type degeneration.

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Fusarium and late blight (fungal diseases of cereals and potatoes) are among the main causes of crop loss worldwide. A key element of success in the fight against phytopathogens is the timely identification of infected plants and seeds. That is why the development of new methods for identifying phytopathogens is a priority for agriculture.

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Hydration plays a fundamental role in DNA structure and functioning. However, the hydration shell has been studied only up to the scale of 10-20 water molecules per nucleotide. In the current work, hydration shells of DNA were studied in a solution by terahertz time-domain spectroscopy.

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The present study describes the synthesis of pyridinium derivatives of betulin, including new 4-methyl- and 3,5-methyl-pyridinium analogs, their effect on artificial membrane systems (liposomes), cytotoxicity in models of prokaryotic (E. coli K-12 MG1655) and eukaryotic cells (rat thymocytes), as well as their effect on the functioning of membrane systems of rat liver mitochondria. We have shown that the presence of methyl groups in the pyridine ring of compounds determines the ability of the derivatives to effectively permeabilize the artificial membrane of lecithin liposomes for the fluorescent probe sulforhodamine B.

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Studying dielectric properties of heterogeneous systems is challenged by a problem of uncertainty of the ratio between dielectric permittivity of the system and dielectric permittivities of its components. Such ratios can be obtained in some cases using theoretical effective medium models. However, such models have not yet been developed for all the systems possible.

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In photoluminescence spectroscopy experiments, the interaction mode of the polymer membrane Nafion with various amino-acids was studied. The experiments were performed with physiological NaCl solutions prepared in an ordinary water (the deuterium content is 157 ± 1 ppm) and also in deuterium-depleted water (the deuterium content is ≤1 ppm). These studies were motivated by the fact that when Nafion swells in ordinary water, the polymer fibers are effectively "unwound" into the liquid bulk, while in the case of deuterium-depleted water, the unwinding effect is missing.

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ATP is one of the main biological molecules. Many of its biological and physicochemical properties, such as energy capacity of the phosphate bonds, significantly depend on hydration. However, the structure of the hydration shell of the ATP molecule is still a matter of discussion.

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The dependence of the volume number density of ion-stabilized gas nanobubbles (bubstons) on the type of gas and the pressure created by this gas in deionized water and saline solution has been investigated. The range of external pressures from the saturated water vapor (17 Torr) to 5 atm was studied. It turned out that the growth rate of the volume number density of bubstons is controlled by the magnitude of the molecular polarizability of dissolved gases.

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