Vol 25, No 2 (2021): EXPERIMENTAL AND CLINICAL PHYSIOLOGY

Objectives: to evaluate the effectiveness of photosensitizer solutions in the experiment in different modifications of standard UV corneal crosslinking. Materials and Methods. Experiments were performed on 32 enucleated porcine eyes ex vivo and 12 rabbits (24 eyes) in vivo, divided into 4 groups depending on instillations of the photosensitizer solutions: «Dextralink», «Ribolink», «Hypolink» and «Riboflavin». Evaluation of corneal saturation was performed using two modifications of standard UV CXL: in the first case, instillation of the photosensitizer solution was performed during the entire crosslinking procedure (30 min - saturation and 30 min - ultraviolet irradiation); in the second case, instillations lasted only for the first 30 minutes, the precorneal riboflavin film was removed, and instillation of solution was not performed. Results and Discussion. Instillation of photosensitizer solutions within 60 minutes showed that Dextralink significantly reduced the thickness of the cornea by about 24 % ex vivo and 21 % in vivo, while Hypolink, on the contrary, caused its increase by 9 % ex vivo and 23 % in vivo, respectively. The use of Ribolink and Riboflavin did not change the linear parameters of the cornea during the entire follow-up period. The results of the 2nd series of studies showed that effects of solutions on the cornea during their instillation for 30 minutes were generally preserved during the entire observation period up to 60 minutes. In the group where Dextralink and Hypolink solutions were used, there was a slight tendency to normalization of the initial parameters of the cornea. Conclusion. Safe and effective implementation of UV crosslinking of the cornea is possible on the basis of a rational approach to the performing the stages of stroma saturation with photosensitizer solutions, depending on the initial state of the cornea: Dextralink is recommended for a thickness of more than 450 µm, Ribolink - at 400-450 µm, Hypolink - from 350 to 400 µm. Halting of instillations on the saturated stroma during UV irradiation is advisable to be accompanied by intraoperative control of its thickness. When performing a standard crosslinking technique, where instillations of photosensitizer accompany the stage of UV irradiation of the cornea, it is necessary to take into account the presence of a precorneal film that can absorb some of the radiation energy. The peculiarity of this crosslinking technique can be considered as a potential way to protect intraocular tissues from excessive exposure to UV radiation.

Brain development is a unique process characterized by mechanisms defined as neuroplasticity (synaptogenesis, synapse elimination, neurogenesis, and cerebral angiogenesis). Numerous neurodevelopmental disorders brain damage, and aging are manifested by neurological deficits that are caused by aberrant neuroplasticity. The presence of stem and progenitor cells in neurogenic niches of the brain is responsible for the formation of new neurons capable of integrating into preexisting synaptic assemblies. The determining factors for the cells within the neurogenic niche are the activity of the vascular scaffold and the availability of active regulatory molecules that establish the optimal microenvironment. It has been found that regulated intramembrane proteolysis plays an important role in the control of neurogenesis in brain neurogenic niches. Molecules generated by the activity of specific proteases can stimulate or suppress the activity of neural stem and progenitor cells, their proliferation and differentiation, migration and integration of newly formed neurons into synaptic networks. Local neoangiogenesis supports the processes of neurogenesis in neurogenic niches, which is guaranteed by the multivalent action of peptides formed from transmembrane proteins. Identification of new molecules regulating the neuroplasticity (neurogenesis and angiogenesis). i. e. enzymes, substrates, and products of intramembrane proteolysis, will ensure the development of protocols for detecting the neuroplasticity markers and targets for efficient pharmacological modulation.

Relevance. The focus of modern dental treatment not only on the elimination of aesthetic, but also functional disorders requires an understanding of the functional conjugation of the chewing muscles, the possibility of interprognosis of parameters. Objective. Assess the functional relationship between the tone of the chewing muscles proper and the bioelectric activity of the temporal and sublingual muscle groups in children with anomalies of the dentoalveolar system. Materials and Methods. The study involved 36 patients of Children’s Clinical Dental Clinic No. 2 of Voronezh, aged 6 to 12 years, who had not previously received orthodontic treatment and had distal occlusion anomalies. Evaluation of the bioelectric activity of temporal and sublingual muscles was carried out using surface electromyography on the Electromyograph Dental apparatus (Taganrog, Russia), the Chewing General sample. Evaluation of the tone of the chewing muscles proper was carried out using the Mioton-3C device in a state of physiological rest of the lower jaw. Statistical processing was carried out using Microsoft Excel, version 7.0 and the statistical programs SPSS Statistics 21 and STATISTICA 7. Results and Discussion. Correlation analysis revealed the presence of 4 weak positive, 2 weak negative, 14 moderate positive, 3 moderate negative, and 1 noticeable positive correlation between the tone of the right chewing muscle proper and the parameters of the bioelectric activity of the right and left temporal and sublingual muscles. Correlation analysis revealed the presence of 5 weak positive, 7 weak negative, 9 moderate negative correlations between the tone of the left chewing muscle proper and the parameters of bioelectric activity of the right and left temporal and sublingual muscles. Conclusion. A greater effect of the tone of the right chewing muscle on the bioelectric activity of temporal and sublingual muscles was found compared to the tone of the left chewing muscle itself. 27 equations have been derived that can be used as predictive models for calculating the tone of right and left chewing muscles proper depending on the indicators of bioelectric activity of temporal and sublingual muscles.

In forensic medical practice, when diagnosing the cause of death from blood loss, it is often necessary to solve questions related to the etiology of loss of circulating blood volume (CBV), the degree and severity of the injury, as well as its role in thanatogenesis and the duration of the terminal (agonal) period. When investigating the cases of death from acute blood loss, the authorities often ask forensic experts to solve issues related to the possibility of performing active targeted actions by the dying person, as well as to assess the timeliness of medical care and the actions of medical personnel. The solution of these issues is often difficult for experts, and it is associated with both objective and subjective reasons. For example, in cases where the circumstances of death are unknown, or there are no medical documents, or they do not contain sufficient information, without which it is impossible to conduct a retrospective clinical and anatomical analysis for the purpose of differential diagnosis between hemolytic shock and post-hemorrhagic anemia. The article deals with the use of new methodological approaches in postmortem morphological diagnostics of blood loss by the rate of its development and its role in thanatogenesis, in forensic medical practice. For example, a particular forensic expertise (case study) shows that the application of two new methods allowed to solve the issues for the investigator related to the cause of death and duration of dying from blood loss. Experts’ knowledge of new methodological approaches to the forensic diagnosis of acute blood loss will help law enforcement authorities to counteract crimes against the life of citizens, as well as to development the measures to improve the methods for prevention and reduction of mortality from traumatic injuries with blood loss.