Biophysics最新文献

Hafnium is a promising element as contrast agent for diagnostic and therapeutic radiology. Currently there are no suitable hafnium drugs with renal excretion which can be used in radiology. In this work two new hafnium complexes with nitrilotriacetic acid (Hf-NTA) and 1,2-diaminocyclohexanetetraacetic acid (Hf-CDTA) were synthesized and studied for acute toxicity and biodistribution. Inorganic chemistry methods were used for Hf-NTA and Hf-CDTA synthesis. Acute toxicity was studied in female mice C57Bl/6. Median lethal dose (LD50) of Hf-CDTA was assessed as 408 ± 64 mg Hf/kg and of Hf-NTA less than 120 mg Hf/kg. Biodistribution and contrast properties studies of Hf-CDTA were performed in vivo using micro-CT in mice with transplanted subcutaneous mammary adenocarcinoma Ca755. CT imaging of mice intravenously injected with Hf-CDTA confirmed its renal excretion and contrast capability. CT imaging of tumor region with single intratumoral administration of Hf-CDTA showed promising hafnium concentration and retention in tumor for use in contrast-enhanced radiotherapy. Hf-CDTA showed acceptable toxicity and biodistribution in mice with subcutaneous tumors for biomedical application in radiology and radiotherapy. For diagnostic clinical application, the Hf-CDTA formulation must be improved to increase water solubility and decrease toxicity. Hf-NTA appeared to be unacceptably toxic for radiological application.

It has been shown using experimental (electron paramagnetic resonance) and quantum chemical (density functional theory) research methods that the previously observed changes in the electron paramagnetic resonance spectrum of the semiquinone Tiron radical in seawater are due to its interaction with Mg²⁺ ions. The formation of a complex between Mg²⁺ and the Tiron radical is due to the electrostatic attraction of ions carrying large charges of the opposite sign (+2 and –3), on the one hand, and the ability of Mg²⁺ ions to bind effectively to bidentate oxygen-containing ligands, on the other hand. The formation of tight contact ion pairs leads to a redistribution of the electron and spin density in the Tiron radical, which can be judged by the observed changes in the electron paramagnetic resonance spectrum of this radical.

The reason for the lack of the hypotensive effect of gaseous NO, as introduced by inhalation into the bodies of animals and humans, has been identified. Since this defect was completely eliminated by inhalation of NO simultaneous with intravenous administration of low molecular mass thiol solutions to animals (rats), it is concluded that gaseous NO entering through the lungs into the blood circulating in a large circle of blood circulation converts into nitrosonium cation (NO⁺) as a result of single-electron oxidation, which is unable to exert vasodilating and thereby hypotensive effects on animals and humans. The binding of NO⁺ to low molecular mass thiols leads to its transformation into S-nitrosothiols, followed by the release of this nitrosyl agent in the form of neutral NO molecules characterized by hypotensive activity. The formation of dinitrosyl iron complexes with thiol-containing ligands in the blood and tissues of organs of experimental animals in these experiments, which could cause a hypotensive effect, was not detected. The hypotensive effect of inhaled NO, which was found in the lungs, could be due to the penetration of NO through the outer wall of blood vessels with subsequent activation of the enzyme guanylate cyclase, an inducer of vasodilation and hypotension, directly in the walls of blood vessels.

Biosensor analysis methods are being actively improved and are becoming increasingly important in the fields of safety, medicine, in particular, cancer monitoring, environmental quality control, etc. In this paper, we considered the development of a biosensor system based on the technology of using the olfactory bulb (OB) of macrosmatic animals with optical methods of imaging odorant-specific patterns of glomerular activity. The difficulties of automatic detection of odor-triggered patterns during repetitive stimulation are due to adaptation processes manifested in a reversible change in the sensitivity of the neural structures of the olfactory analyzer. The optimal duration of stimuli and interstimular intervals has been experimentally found; this made it possible to stabilize the glomerular response during repeated stimulation and visualize patterns of glomerular activity with constant accuracy. The results we obtained expand the existing tools used for the development of biosensor systems.

The study of the degree of hydrolysis depending on the action of various proteolytic enzymes is one of the tasks in the development of nutraceuticals from connective tissues for biomedicine. Hydrolysis of biopolymers in hyaline cartilage homogenates from the trachea of cattle and pigs was carried out under the action of the enzymes pancreatin, chymopsin, papain, and the proteolytic drug karipazim containing papain. It has been shown that karipazim produced by MedFlorina acted more effectively than karipazim produced by Vifitech, and the degree of collagen hydrolysis was maximal at 60°C and a concentration of karipazim of 10%. A more complete hydrolysis of proteoglycans was observed in the homogenates of hyaline cartilage of cattle, since glucose, the final product of glycosaminoglycan hydrolysis, was identified on NMR spectra.

The influence of the composition and physicochemical properties of lecithin lipids, the duration of exposure to ultrasound, and centrifugation on the composition and physicochemical properties of liposomes formed from lecithin has been studied. It has been revealed that the intensity of lipid peroxidation has an inverse correlation with the phospholipid level in the total lipid composition of lecithin and a direct correlation with the relative content of cardiolipin in the composition of lecithin phospholipids. It has been shown that the duration of ultrasound exposure and centrifugation causes changes in the composition and properties of the liposome lipids. Decreases in the pH of the medium and the intensity of lipid peroxidation of liposomes were observed under centrifugation. It was revealed that the changes in the ability of the liposome lipids to oxidation depending on the duration of ultrasound exposure and centrifugation are due to the relative changes in the sum percentage of the acidic minor fractions in the composition of their phospholipids.