Vol 64, No 1 (2019)

Abstract—The efficiency of cryoprotectants used to protect cells from damage is usually evaluated by the changes in vital cell parameters after a freezing–thawing cycle. Certain physical parameters, such as the glass transition temperature, viscosity, toxicity, and the minimum concentration necessary for vitrification, are known for several components of cryoprotectants. However, it is impossible to provide physicochemical characteristics for a medium that contains both penetrating and nonpenetrating cryoprotective agents. An adiabatic calorimetry method adapted to studying liquid media was used to describe the temperature dependence of the heat capacity and to find the temperatures of the phase transition and changes in the state of aggregation for a glycerol-containing solution, which is commonly used as a basic component of cryoprotectants, and for a commercial cryoprotectant. Changes in entropy and enthalpy in the commercial cryoprotectant were 1.5 times higher than in aqueous solutions of glycerol.

Abstract—Differential scanning calorimetry (DSC) analysis was used to study the dependences of the main parameters of crystallization and melting of small water clusters dispersed in Sephadex resins on the amount of water (30–55%) in the wet polymer. The temperatures and heats of the processes were shown to depend on the frozen water (FW) concentration in Sephadex, with the dependence being considered as a manifestation of the size effect. Hysteresis between FW melting and crystallization was detected in a certain Sephadex humidity range; i.e., T_m was higher than T_cr and Q_m higher than Q_cr. The two findings reflected the basic properties of low-dimensional systems. Sephadex and amorphous starch, which was examined previously, were compared as two polysaccharide systems with different structural organizations, and a significant difference was observed in FW crystallization in the systems. Nucleation and crystallite growth, which determine water crystallization, were found to occur separately in time in Sephadex with a low humidity under these experimental conditions. Nucleation occurred during cooling, while growth was observed mainly during heating. Both of the processes occurred during cooling and partly overlapped only at a high humidity, far from T_g of Sephadex. In contrast, the two processes always occurred during cooling in amorphous starch regardless of its humidity. The difference in FW crystallization was assumed to arise because water mobility differs between the systems as a result of their difference in molecular mobility of the biopolymer matrix proper near the glass transition region.

Abstract—We consider a previously proposed method for encapsulation of enzymes, which employs the layer-by-layer adsorption of oppositely charged polyelectrolytes onto composite spherulites (calcium carbonate/protein) followed by dissolution of the calcium carbonate support. The goal of this work is to choose conditions for encapsulation of the enzyme horseradish peroxidase by the method so that the catalytic activity of the encapsulated enzyme would be comparable with that of the soluble one. The steps of the fabrication of polyelectrolyte microcapsules with the studied enzyme have been tested. A protocol for obtaining composite spherulites of the desired size ranging from 2 to 10 µm has been developed. It is shown that the catalytic activity of horseradish peroxidase encapsulated in a microcapsule with a positively charged inner surface of the microcapsule envelope (the inner layer modified by polycation polyallylamine hydrochloride) is significantly higher than that of the enzyme encapsulated in a microcapsule with a negatively charged inner layer (modified by polyanion sodium polystyrene sulfonate). At the support dissolution step, ethylene glycol bis-(β-aminoethyl) tetraacetic acid (EGTA), a decalcifying agent used to dissolve CaCO₃ from horseradish peroxidase microcapsules, is significantly less detrimental to enzymes than ethylene diamine tetraacetic acid. The catalytic activity of horseradish peroxidase encapsulated in polyallylamine hydrochloride/sodium polystyrene sulfonate/polyallylamine hydrochloride microcapsules (with positively charged inner surface of the microcapsule envelope) is 60–70% of the activity of the soluble enzyme (in experiments where the calcium-carbonate support of the composite spherulites is dissolved with EGTA).

Abstract—Using Raman spectroscopy, atomic force microscopy, and laser interferometry we found that variations in insulin-like growth factor (IGF-1) and purinergic compounds such as ATP in the blood influence the hemoglobin distribution and hematoporhyrin conformation in hemoglobin in erythrocytes. Our results suggest that receptor activation promotes changes in conformation of cytoskeletal protein molecules and hemoglobin.

Abstract—The effects of sensory stimulation on the model of paired Mauthner neurons of monocularly deprived goldfish have been studied by light- and electron microscopy. Three-dimensional reconstruction was performed using serial semi-thin sections in order to determine the volumes of soma and dendrites for the right and left Mauthner neurons. These data suggested that long-term stimulation of some fish caused a decrease in the volume of the lateral dendrites of neurons contralateral with respect to the side of the enucleated eye. As a result, the morphological homeostasis in the dendrites of Mauthner neurons, which was observed in the control fish, was disturbed after the effect of stimulation upon this group of fish. The main mechanism of this effect of stimulation, according to ultrastructural analysis, is the compaction of the cytoskeleton in the lateral dendrite of a neuron and a reduction in the number of synaptic vesicles in the region of afferent synapses. In contrast, stimulation of the remaining fish induced the resistance of the contralateral Mauthner neuron to prolonged stimulation, as well as the hypertrophy of its lateral and shortening of the ventral dendrites. These results suggest that the homeostasis of the dendrites of Mauthner neurons essentially depends on the state of the visual inputs, the load on which increased as a result of the doubled impact.

Abstract—The amounts of lipofuscin (age pigment) were compared in four organs of rats: the liver, the kidney, the heart muscle, and the brain, as well as in a suspension of ghosts of hepatic mitochondria. It was shown that liver lipofuscin, which absorbs UV light at 360 nm and fluoresces at 460 nm, is predominantly formed due to mitochondrial processes. The lowest lipofuscin content was observed in the heart muscle; in the other organs studied, the levels of lipofuscin calculated per mg of protein were approximately the same. The spectral data and the lifetime of the excited state suggest that a considerable contribution to the fluorescence of lipofuscin in various organs belongs to mitochondrial lipofuscin. Along with lipofuscin, a fluorescent pigment, all organs were shown to contain non-fluorescent protein aggregates: their level was the highest in the heart muscle and the lowest in the liver. Among them, a significant portion were covalently cross-linked aggregates that were not destroyed by detergent treatment. Moderate heating of the organ homogenates caused the formation of thermolipofuscin. The level of thermolipofuscin production was the highest in the brain and the lowest in the heart. Apparently, a significant portion of the thermolipofuscin that formed in organ homogenates was thermomitochondrial lipofuscin from the membranes of damaged mitochondria. The formation of thermolipofuscin strongly involved aromatic residues: tyrosine and tryptophan.

Abstract—The objective of this work was to study the biological effect of dinitrosyl iron complexes (DNICs) with the glutathione ligand (GSH−DNICs) as a stabilized form of nitric oxide in a rat model of nitric oxide hyperproduction induced by inflammation. Administration of GSH−DNICs in endotoxin shock did not increase the total nitric oxide levels in rat organs, but exerted a protective effect by suppressing nitric oxide hyperproduction in the liver and led to an accumulation of the complexes with protein ligands in the kidney.

Abstract—Nature is known to minimize the energy costs of water flow in the vascular bundles of plants and the blood vessels of animals. However, until recently, the mechanisms of this phenomenon remained unknown. The superfluidity of aqueous solutions that was recently discovered made it possible to develop a scientific basis and overcome many problems concerning this phenomenon. Vascular systems, which carry vital biological fluids, penetrate literally through all of the plants and animals on Earth. A variety of minerals are dissolved in soil water and blood plasma, which results in electrically charged conducting systems. All this enables manifestation of superfluidity in vascular systems of plants and animals. Superfluidity is an equivalent of viscosity reduction in fluids to values that are much lower than it can be expected.

Abstract—The experimentally revealed high phase coherence between low-frequency oscillations in the cutaneous blood perfusion signal at the contralateral skin sites indicates the existence of a central mechanism of its regulation. The vascular bed can be such a regulatory mechanism because it is a closed hydrodynamic system. It has been shown in this study using a mathematical model of the human cardiovascular system that the impact of low-intensity stochastic perturbations on the stiffness of the cardiac ventricles leads to the formation of low-frequency oscillations in microvascular blood flow. The results show that there is a relationship between the activity of the heart and low-frequency oscillations of microcirculatory skin blood flow, which is due to the hydrodynamic properties of the vascular bed without the involvement of autonomous control from autonomic nervous system.

Abstract—We propose a multiparametric equation for calculation of the average natural lifespan of various vertebrate species, including well-known mammalian “outliers,” such as the naked mole rat and bat. This equation includes body and brain weights; durations of puberty, sleep, and hibernation; daily food intake; oxygen consumption; and body temperature. We infer that aging is the result of protein and DNA damage that accumulate during animal life cycles rather than a genetic program that underlies phenoptosis.