On 7th October the Academic Council of Medical University - Varna elected Stefan Krastev, Doctor in Biophysics, to take the academic position "Associate Professor" in the professional field Biological Sciences and the scientific specialty Biophysics.
The topics of Assoc. Prof. Stefan Krastev's publications are predominantly related to the application of the methods of scientific modelling (mathematical and physical); experimental methods, tools and practical research, related to the study of the effects of various physical factors on biological objects and systems; issues related to the organization and improvement of the training process.
Firstly, the publications reflecting the collaboration with the team of Prof. Diana Stefanova from "Excitable Structures" Department at the Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences (BAS) are among the most significant scientific contribution. The effect of liquid layers in the myelin sheath of motor nerve fibers in simulated demyelinating neuropathies has been studied for the first time in the scientific literature. Temperature and its effect on the properties of the excitability of human motor nerve fibers have been investigated. Furthermore, the kinetics of nodal and internodal ionic trans-axonal and transmembrane currents on the generation of action and electrotonic potentials in simulated cases of amyotrophic lateral sclerosis has been examined. The developed physical models and study experiments have direct application in the teaching process of medical specialties.
The main contributions of Assoc. Prof. Krastev аrе in the field of computer modelling and numerical experiments, related to the generation and distribution of the action potentials in myelinated human axons in norm and in simulated various neurodegenerative diseases. No matter in what direction the effects of the liquid layers are (improvement or deterioration of the axonal membrane excitability), a conclusion has been drawn that they reflect the simulated neuropathies properly, which supports the adequacy of the applied mathematical model in the computer simulation. The obtained results further elucidate some of the mechanisms, determining the damages in hereditary and chronic inflammatory demyelinating neuropathies. Demyelinating neuropathies are diseases which result in irreversible damages to the motor system and to severe disability of sufferers, who are often young people and even individuals in childhood. Due to their great social significance, the lack of successful treatment and the fact that the pathological mechanisms are not elucidated in their entirety, the research of Assoc. Prof. Krastev is particularly relevant and significant.
Through the method of computer modulating Assoc. Prof. Krastev succeeds in simulating three degrees of the disease amyotrophic lateral sclerosis (ALS), whereupon the kinetics of nodal and internodal ionic trans-axonal and transmembrane currents, determining the generation of action and electrotonic potentials, as well as the recovery cycles have been investigated.
The results of the two-dimensional mathematical model of the regulation of blood glucose in humans, obtained by Assoc. Prof. Krastev, are also of great interest. Under this model, in contrast to previous patterns, the real non-zero level of insulin is measured and it also involves the effect of the observed in clinical studies rapid insulin response of the pancreas at above-threshold concentration of blood glucose. Owing to the leading part of the author, this two-dimensional mathematical model with computer simulation is applied in the training in Biophysics for medical students, whereupon for the first time, a laboratory exercise, studying the regulation mechanism of blood glucose in humans by the method of the mathematical modelling has been developed and introduced.