Correlative Fluorescent Scanning Probe Nanotomography Used to Study the Intracellular Distribution of Doxorubicin in MCF-7 Human Breast Adenocarcinoma Cells.

Developing technologies for efficient targeted drug delivery for oncotherapy requires new methods to analyze the features of micro- and nanoscale distributions of antitumor drugs in cells and tissues. A new approach to three-dimensional analysis of the intracellular distribution of cytostatics was developed using fluorescence scanning optical-probe nanotomography. A correlative analysis of the nanostructure and distribution of injected doxorubicin in MCF-7 human breast adenocarcinoma cells revealed the features of drug penetration and accumulation in the cell. The technology is based on the principles of scanning optical probe nanotomography and is applicable to studying the distribution patterns of various fluorescent or fluorescence-labelled substances in cells and tissues.

Identification of Ultrastructural Details of the Astrocyte Process System in Nervous Tissue of the Brain Using Correlative Scanning Probe and Transmission Electron Microscopy.

Nanoscale morphological features of branched processes of glial cells may be of decisive importance for neuron-astrocyte interactions in health and disease. The paper presents the results of a correlation analysis of images of thin processes of astrocytes in nervous tissue of the mouse brain, which were obtained by scanning probe microscopy (SPM) and transmission electron microscopy (TEM) with high spatial resolution. Samples were prepared and imaged using a unique hardware combination of ultramicrotomy and SPM. Astrocyte details with a thickness of several tens of nanometers were identifiable in the images, making it possible to reconstruct the three-dimensional structure of astrocytic processes by integrating a series of sequential images of ultrathin sections of nervous tissue in the future.

Hydrogels Based on Recombinant Spidroin Stimulate Proliferation and Migration of Human Corneal Cells.

The effect of recombinant spidroin (RS) hydrogel (HG) on anterior epithelial cells and keratocytes of the human cornea was studied in vitro. Corneal injuries are highly prevalent in developing countries according to the World Health Organization. Various technologies have recently been proposed to restore the damaged surface of the cornea. Use of biodegradable silk-based materials, including recombinant analogs of the spider silk protein spidroin, is an important avenue of research in the field of wound healing and corneal regeneration. Spidroins are well known for their optimal balance of strength and elasticity. Given their biological compatibility, lack of immunogenicity, and biodegradability, spidroins provide a biomaterial for tissue engineering and regenerative medicine. HGs based on RS rS2/12-RGDS were therefore tested for cytotoxicity toward isolated corneal epithelial cells and keratocytes with regard to possible changes in cell phenotype and migratory activity. A promising outlook and therapeutic potential were demonstrated for RS-based HGs.

Investigation of the Distribution of Magnetic Nanoparticles in Tumor Tissues by the Method of Scanning Magnetic Force Nanotomography.

The development of effective biomedical technologies using magnetic nanoparticles (MNPs) for the tasks of oncotherapy and nanodiagnostics requires the development and implementation of new methods for the analysis of micro- and nanoscale distributions of MNPs in the volume of cells and tissues. The paper presents a new approach to three-dimensional analysis of MNP distributions - scanning magnetic force nanotomography as applied to the study of tumor tissues. Correlative reconstruction of MNP distributions and nanostructure features of the studied tissues made it possible to quantitatively estimate the parameters of three-dimensional distributions of composite nanoparticles based on silicon and iron oxide obtained by femtosecond laser ablation and injected intravenously and intratumorally into tumor tissue samples of B16/F1 mouse melanoma. The developed technology based on the principles of scanning probe nanotomography is applicable for studying the features of three-dimensional micro- and nanoscale distributions of magnetic nanoparticles in biomaterials, cells and tissues of various types.

[Chordoma as a neurosurgical pathology]. / Khordoma kak neirokhirurgicheskaya patologiya.

OBJECTIVE: Assess the significance of chordoma as a neurosurgical pathology, taking into account the latest edition of the WHO classification of soft tissues and bone tumors (2020). MATERIAL AND METHODS: An analysis of 28 chordomas was carried out. All chordomas were histologically verified, including using immunohistochemical markers of notochordal differentiation (S100, EMA, keratin, brachiuria protein). RESULTS: Patients with chordomas accounted for 0.25% of the total number of neurosurgical patients. The vast majority (27) of chordomas had a cranio-vertebral localization. Sacral localization (S3-S5) of the tumor was detected in 1 patient. In 4 (15%) cases, operations were performed for the recurrence of chordoma. The tumors tended to grow into the structures of the skull, overgrown the vessels and nerves, and compress the adjacent brain structures. This was manifested by pain syndrome, neurological symptoms, impaired liquorodynamics. According to histopathological criteria, 27 (96%) cases of tumors were classified as conventional (usual) chordoma type, among them 7 corresponded to the chondroid subtype of the chordoma. In 1 case (4%), a dedifferentiated chordoma was detected. CONCLUSION: Chordoma, due to its axial localization, naturally involves adjacent structures of the nervous system, has clinically significant neuropathological manifestations, and often provides direct indications for a special neurosurgical approach. This requires its consideration not only as a bone, but also as a neurosurgical oncological pathology, along with other non-meningothelial (mesenchymal) tumors of the CNS.

[Influence of the growth of children on the features of injuries arising during a car injury]. / Vliyanie rosta detei na osobennosti povrezhdenii, voznikayushchikh pri avtomobil'noi travme.

THE AIM OF THE STUDY: Was to establish the features of injuries that occur from a car impact and from an injury in the car cab in children of different heights. A retrospective study of archival material was carried out, including forensic conclusions of the corpses of children under 18 who died as a result of car injuries. We analyzed the frequency of damage to various parts of the body as a percentage in children of different heights. As a result, it was found that in children who died as a result of an accident, both from a car impact and from an injury in the car cab, with an increase in height, death occurs more often from a combined injury, less often from an isolated injury of any one part of the body. In children-pedestrians who died from a car impact, with an increase in height, the localization of fractures of the bones of the upper and lower limbs «moves¼ to more distal regions. The frequency of fractures of the ribs, blades, and pelvic bones increases with increasing height. Ruptures of the liver and spleen are several times more likely to occur in children below 160 cm. In children-passengers with an injury in the car cab, the main features of damage caused by height were identified in the trunk region, which are manifested by a significant predominance of massiveness and the proportion of damage to the bones and internal organs of the chest, the abdomen and pelvis in children above 140 cm and, especially, above 160 cm. Of the injuries of the lower limbs, a feature of the injury in the car cab is the prevalence of injuries to the knee joints in children above 140 cm. A direct dependence of injuries of all parts of the upper limbs on height was revealed, fractures of the forearm bones has been revealed occurred only in children above 160 cm.

Scanning Optical Probe Nanotomography for Investigation of the Structure of Biomaterials and Cells.

Creation of new effective bio-artificial structures for tissue engineering and regenerative medicine requires development and implementation of new technological approaches for analysis of micro- and nanostructural features of constructs based on biomaterials and their interaction with cells. A new method of three-dimensional multiparametric analysis of nanostructure, scanning optical probe nanotomography, is presented in this paper, applied to the analysis of cells and biomaterials. Correlative reconstruction of fluorescent marker distributions and nanostructure features allows quantitative evaluation of a number of parameters of three-dimensional nanomorphology of fibroblasts and human hepatocarcinoma cells Hep-G2, adhered to biodegradable scaffolds based on silk fibroin. The developed technology with use of scanning optical probe nanotomography is applicable to investigation of three-dimensional micro- and nanostructure features of biomaterials and cells of different types.

Surface Modification of Alginate Microcarriers for Improvement of Their Biological Properties.

The obtaining of microcarriers for the cell culture and delivery is an urgent task of tissue engineering and regenerative medicine. The novel method of surface modification of alginate microcarriers in the form of microspheres with a diameter of 200-300 µm was developed. The described method consists in covalent crosslinking between collagen and surface of alginate microcarriers. It was shown that the method makes it possible to completely modify the surface of the alginate microcarrier, which can be used to improve the biological properties of the microcarrier. Such microcarriers with improved biological properties can be considered as effective systems for cell delivery and culture.

The effect of biodegradable silk fibroin-based scaffolds containing glial cell line-derived neurotrophic factor (GDNF) on the corneal regeneration process.

Corneal injury due to ocular trauma or infection is one of the most challenging vision impairing pathologies. The aim of the work was to study the effect of biodegradable silk fibroin-based scaffolds containing GDNF on the corneal regeneration process. During cultivate the highest keratocytes proliferative activity was registered with scaffolds containing 250 ng/ml and 500 ng/ml GDNF. In mice with an experimental model of epithelial-stromal damage to the cornea, silk fibroin-based scaffolds containing GDNF in various concentrations were used (in groups 1, 2 and 3 silk fibroin-based scaffolds containing GDNF in a concentration of 50 ng/ml, 250 ng/ml and 500 ng/ml, respectively; in group 4 - silk fibroin-based scaffolds without GDNF; in group 5 - a solution of GDNF with concentration of 500 ng/ml; group 6- control). The area of the corneal epithelial defect in groups 2, 3, and 5 was less than in the other groups. The most pronounced positive immunohistochemical reaction with antibodies to Bcl2, Bax, phosphoERK1/2 and phospho-JNK1/2, Ki67, Gap43 was observed in groups 2 and 3. Thus, silk fibroin-based scaffolds with GDNF stimulate the epithelialization process, proliferative activity of epithelial cells and keratocytes, accelerate the formation of the stromal nerve plexus and exhibit anti-apoptotic activity.

[Features of diagnosis and treatment of elderly and senile patients with adhesive small bowel obstruction.]

Adhesive small bowel obstruction is a common pathology with a tendency to increase characterized by a complex pathogenetic course with a high percentage of complications and deaths. Among the forms of intestinal obstruction caused by mechanical obstacles acute small bowel obstruction ranges from 64,3 to 80% with a mortality rate of 5,1 to 8,4% in the structure of urgent diseases. The complexity of early diagnosis along with an erased clinical picture severe course against a burdened background as well as age - in elderly and senile people leads to the search for new optimized treatment and diagnostic protocols. The purpose of this study was to study the nature of the course of adhesive small bowel obstruction in elderly and senile people to establish the information content of various diagnostic methods to determine the indications for the choice of the optimal period and method of treatment. A comparative analysis of 191 patients aged 60 to 90 years and older who received treatment in the surgical departments of St. Elizabeth Hospital (St. Petersburg) in the period from 2016-2019 was carried out. All patients were divided into 2 groups: the main group consisted of 106 patients (2018-2019) the comparison group included 85 patients (2016-2017). All patients of the main group used an improved diagnostic and treatment algorithm with the use of an original point-assessment scale which made it possible to optimize diagnostics and improve treatment results. Patients in the comparison group were examined in accordance with standard protocols and surgical treatment was carried out exclusively by traditional methods. The use of the proposed therapeutic and diagnostic algorithm made it possible to increase the probability of conservative resolution of acute adhesive small bowel obstruction from 20% (17) to 33% (35) and to reduce the incidence of postoperative complications from 60,2% (41) to 25,3% (18), p<0,01, and the mortality rate from 23,5% (16) to 7% (5), p<0,05.

O antigen restricts lysogenization of non-O157 Escherichia coli strains by Stx-converting bacteriophage phi24B.

Acquisition of new prophages that are able to increase the bacterial fitness by the lysogenic conversion is believed to be an important strategy of bacterial adaptation to the changing environment. However, in contrast to the factors determining the range of bacteriophage lytic activity, little is known about the factors that define the lysogenization host range. Bacteriophage phi24B is the paradigmal model of Stx-converting phages, encoding the toxins of the Shiga-toxigenic E. coli (STEC). This virus has been shown to lysogenize a wide range of E. coli strains that is much broader than the range of the strains supporting its lytic growth. Therefore, phages produced by the STEC population colonizing the small or large intestine are potentially able to lysogenize symbiotic E. coli in the hindgut, and these secondary lysogens may contribute to the overall patient toxic load and to lead to the emergence of new pathogenic STEC strains. We demonstrate, however, that O antigen effectively limit the lysogenization of the wild E. coli strains by phi24B phage. The lysogens are formed from the spontaneous rough mutants and therefore have increased sensitivity to other bacteriophages and to the bactericidal activity of the serum if compared to their respective parental strains.

[Relationship between the Interhelical Packing Angles and the Length of α-Helices in Proteins].

Mutual arrangement, or packing, of α-helices in proteins depends on several factors, but, tight packing and the chemical nature of the polypeptide chain are the most important. This study shows, for the first time, that the torsion packing angles between axes of α-helices depend on their length. A database of helical pairs formed by two connected and juxtaposed α-helices has been compiled using the Protein Data Bank. These helical pairs have been subdivided into four types: (1) 10474 pairs formed by long helices; (2) 3665 pairs in which the first α-helix is long and the second is short; (3) 3648 pairs in which the first α-helix is short and the second is long; 4) 1895 pairs in which both helices are short. Analysis of the database showed that most helical pairs in which both the helices are long form α-hairpins having interhelical packing angles of Ω. ≈ 20°. Most helical pairs in which one α-helix is long and the other is short or both helices are short form αα-corners having orthogonal (Ω ≈ -70°...-90°) or slanted (Ω ≈ -50°) packing of α-helices. The possible reasons for this relationship between interhelical angles (Ω) and the length of α-helices are discussed. These results are of great importance in protein modeling and prediction since they enable the determination of the mutual arrangement of α-helices in protein molecules.

[The influence of certain factors on the specific features of the injuries inflicted to the children involved in the motor vehicle traffic accidents]. / Vliianie nekotorykh faktorov na osobennosti povrezhdenii, voznikaiushchikh v usloviiakh avtomobil'noi travmy u detei-passazhirov.

The objective of the present study was to elucidate the influence of the age of the child, its location in the passenger compartment of the vehicle, and the application of the safety seat belts on the frequency of the injuries inflicted to the children involved in the motor vehicle traffic accidents. The analysis of the relevant clinical materials has demonstrated the non-uniform influence of the factors being evaluated on the specific features of the injuries to the different parts of the children's body. The age of the child was found to have the most pronounced effect on the character of the injuries. Direct correlation was documented between the age and the frequency and severity of the injuries to the body and bone of the lower legs whereas the frequency and severity of the fractures of the femoral bones as well as of the craniocerebral traumas showed inverse correlation with the age. The bones of the upper arm and the forearm are most frequently fractured in the 3-6-year-old children. The location of the child in the passenger compartment at the moment of the accident also influences the character of the injury. The front seat passengers most frequently suffer the severe injuries to the head and the fractures of the lower extremities. The injuries to the body and the fractures of the upper extremities occur more frequently in the children occupying the back seats. Fixation of the children with the safety belts is an important factor having the influence on the frequency and severity of the injuries caused to the body and the lower extremities in the children in the passenger compartment of a car. The absence of fixation increases the occurrence of injuries to the internal organs of the chest and abdominal cavities and of the fractures of the thoracic and pelvic bones. Moreover, the frequency of fractures of the femoral, mid- and lower leg bones increases.

Infrared Fluorescent Angiography during Experimental Trachea Transplantation.

Indocyanine green fluorescence was used for evaluation of the degree of trachea revascularization after its autotransplantation in rabbits (transplantation of 1- and 2-cm segment of the trachea). Intravenous administration of indocyanine green was followed by a significant fluorescence of the substance in microvessels of the trachea over 30-40 sec. Immediately after surgery, fluorescence in the implanted segment was absent, but within 7 days it was completely restored in rabbits receiving transplantation of a 1-cm segment. After transplantation of 2-cm segment of the trachea, fluorescence did not recover, which corresponded to the clinical picture and autopsy results. Thus, fluorescent angiography is an informative method for evaluation of trachea revascularization.

Chirality and Handedness of Protein Structures.

In proteins, the polypeptide chain forms a number of right- and left-handed helices and superhelices, right- and left-turned hairpins, and some other structures that are nonsuperimposable, although they are not mirror images of each other as the L-amino acids are not converted to the D-amino acids. This property of protein structures will be referred to here as pseudo-chirality - or handedness. It has been shown that there are two kinds of handedness in proteins - helical handedness and handedness of arrangement. Some protein structures exhibit both the kinds of handedness. Handedness is observed at all levels of protein structural organization - from α-helices, ß-strands, hairpins, ßαß-units up to complex structural motifs, superhelices, and supramolecular structures in fibrous and polymer proteins. There are several structures that have unique handedness in proteins, for example, α-helices, αα-corners, ßαß-units, abcd-units, and so on. This property of the polypeptide chain is of particular value in protein folding and protein modeling, because it drastically reduces the number of possible folds.

[Unique Combinations of ßαß-Units and Π-Like Modules in Proteins and Specific Features of Their Amino Acid Sequences].

Possible combinations of ßαß-units and Π-like modules in proteins in both right- and left-handed forms have been analyzed in detail. The correlation between the mutual arrangement of the structural elements in the polypeptide chain and their handedness has been shown. In the ßαßП combinations, which is encountered most frequently in proteins, the П-module follows the ßαß unit along the chain and both elements are right-handed. In the Пßαß combinations, where the П-module is located at the N end and the ßαß-unit follows it, the former is left-handed and the latter is right-handed. In relatively rare combinations of the left-handed ßαß-units and right-handed П-modules, the ßαß-unit follows П-module in the chain. The combinations of left-handed П-modules and the left-handed ßαß-units are unobservable in proteins. It has also been shown that the П-modules with a ß-strand-α-helix-arch-ß-strand structure are observed in proteins only in a right-handed form and half of them (51%) contains cis-prolines in their arches. These arches of nonhomologous proteins, as well as the positions of cis-prolines, nearly coincide when superimposed. The superimposed П-modules also demonstrate that their overall folds are very similar. Structural alignment of their amino acid sequences has shown that the П-modules have very similar sequence patterns of the key hydrophobic, hydrophilic, glycine, and cis-proline residues.

[Structure and Features of Amino Acid Sequences of L-Modules in SH3-Like Folds].

A novel L-shaped repeat module whose structure can be represented as ß-strand-loop-ß-strand has been identified in a stereochemical analysis of nonhomologous SH3-like folds. ß-Strands of the L-module are positioned at a ~90° angle to each other in different orthogonally packed ß-layers. Together with a crossover loop, they form a half-turn of a right-handed superhelix. A database of 60 nonhomologous SH3-like domains has been compiled using the Protein Data Bank to study structural similarities and differences of L-modules. Occurrence frequencies of L-modules have been determined depending on the length of their loops. It has been shown that L-modules with ßmαααßn- and ßmαααßαßn-conformations, where m and n are numbers of ß-residues in the first and second ß-strands, occur most often (57 and 8%, respectively). Spatial structures of L-modules of the same type are very similar, demonstrated through superimposing them using computer programs. Structural alignment of the amino acid sequences encoding L-modules has been performed, making it possible to identify key positions for hydrophobic, hydrophilic, and proline residues.

[Child-pedestrian injuries inflicted in the road traffic accidents as a forensic medical problem]. / Detskii dorozhno-transportnyi travmatizm kak sudebno-meditsinskaia problema.

The road traffic accidents are known to make the greatest contribution to the overall structure of pediatric traumatism with the fatal outcome. The problem of pediatric traumatism remains on top of its relevancy despite numerous administrative, legal, technical, and financial measures taken at the government level in an attempt to reduce the mortality rate associated with the child-pedestrian injuries inflicted in the road traffic accidents. The objective of the present study was to summarize and interpret the results published in the scientific literature concerning child-pedestrian injuries inflicted in the road traffic accidents with special reference to the age of the victims and the type of the injury. The analysis of the publications of the domestic and foreign authors has demonstrated that the available data of interest remain to be systematized and that the forensic medical aspects of the problem in question are poorly represented in these materials. It was shown that forensic medical expertises of child-pedestrian injuries inflicted in the road traffic accidents are frequently carried out without taking into consideration the peculiar anatomical and physiological features of the child's organism. The available data concerning the mechanisms and evaluation of severe injuries inflicted to the children in the road traffic accidents are insufficient for the development of the algorithms for the relevant adequate forensic medical expertise. In the light of these findings, the problem of the child-pedestrian injuries inflicted in the road traffic accidents takes on new significance when considered in the context of pediatric traumatism. There is evidently the growing necessity to formulate the universal database containing systematized objective information for the development of new methods of forensic medical expertise for the elucidation of the mechanisms of road traffic injuries inflicted to the children of different age groups depending on the type of the injury and the circumstances of the accident. The embodiment of this idea into an action program would allow to address the problem of child-pedestrian injuries inflicted in the road traffic accidents in the framework of the separate division of forensic medical expertise traumatism.

THE MAYAK WORKER DOSIMETRY SYSTEM (MWDS-2013) FOR INTERNALLY DEPOSITED PLUTONIUM: AN OVERVIEW.

The Mayak Worker Dosimetry System (MWDS-2013) is a system for interpreting measurement data from Mayak workers from both internal and external sources. This paper is concerned with the calculation of annual organ doses for Mayak workers exposed to plutonium aerosols, where the measurement data consists mainly of activity of plutonium in urine samples. The system utilises the latest biokinetic and dosimetric models, and unlike its predecessors, takes explicit account of uncertainties in both the measurement data and model parameters. The aim of this paper is to describe the complete MWDS-2013 system (including model parameter values and their uncertainties) and the methodology used (including all the relevant equations) and the assumptions made. Where necessary, Supplementary papers which justify specific assumptions are cited.