by Nozdrachev, Kotel'nikov, Mazhara, Naumov. † Mechanisms regulating the heart rate (HR) continue to be the focus of various studies, which is due to the development of new noninvasive methods for assessing the state of the autonomic nervous system. One such method is spectral analysis of HR variability. It should be noted that the mechanisms responsible for oscillatory modulation of the cardiac rhythm and, consequently, for its spectrum are still obscure to a great extent. To gain a better understanding of them, it is necessary to elucidate the mechanisms controlling the HR. The HR control involves the mechanisms regulating the blood pressure, cardiac output, and total peripheral resistance. However, these issues have been considered in numerous original papers and reviews and are beyond the scope of this work.It is commonly accepted that the HR is determined by the rhythmic activity of pacemaker cells of the sinoatrial node. These cells are capable of spontaneous diastolic depolarization of the membrane potential. Comprehension of the mechanisms of diastolic depolarization is of immense importance for a better understanding of the neural and humoral regulation of the HR.Quantitative studies of ionic currents in pacemaker cells and mathematical models based on their results † Deceased. made it possible to assume the following scenario for rhythm generation [1,2].It is known that the algebraic sum of inward and outward ionic currents across the cell membrane is zero at physiological rest. This is the condition for constancy of the resting potential. Inward currents are carried mostly by sodium ions and, to a lesser extent, by calcium ions. Outward currents are due to potassium ions. A change in their balance to a prevalence of inward currents over outward currents leads to depolarization and, consequently, allows autorhythmic activity. At least two conditions are necessary for this activity to be sustained: (1) at the resting potential, the net inward current exceeds the net outward current by a value sufficient for initiating regenerative depolarization, and (2) at the action potential, the outward current increases to a level sufficient for membrane repolarization such that it abolishes the inactivation of channels carrying the inward current and inactivates channels carrying the outward current. Condition (1) can be accomplished either by primarily increasing the inward (fast or slow) current or by primarily decreasing the outward current. A combination of such changes is also possible. Pacemaker cells employ both of these mechanisms (see below).A specific feature of pacemaker cells of the sinoatrial node is a higher constant background sodium REVIEWS Abstract -Regulation of the cardiac rhythm is intricate and occurs at least at two major levels, intrinsic and extrinsic. In turn, each of these levels can be divided into several sublevels. The factors regulating the cardiac activity eventually affect the duration of spontaneous diastolic depolarization of pacemaker myocytes of the sinoatrial node and, to a ...

In 1887, S.A. Belyakov, a physician of the Imperial Medical and Surgical Academy, first described amyloid deposits in the brain of patients with dementia. Later, in 1906, A. Alzheimer revealed amyloid plaques and tau tangles in a patient with clinical signs of dementia. Over the following 100 years, the development of the concept of the amyloid origin of Alzheimer's disease (AD) confirmed numerous relationships between the brain accumulation of APs and cognitive decline. And if at the beginning of the amyloid era many researchers considered that the disease was caused by amyloid beta (Aβ) protein overproduction, in recent years they have increasingly pointed to a defect in the mechanisms of Aβ clearance, especially after the discovery of the lymphatic system of the brain. The role of disturbed homeostasis of redox-active metals, primarily iron and copper, in the development of the disease is also considered.The amyloid hypothesis of AD has served as the basis for several areas in the design of drugs, such as secretase inhibitors, immunomodulatory drugs for active and passive immunization. However, only one drug (Akatinol memantine, an inhibitor of NMDA receptors and glutamatergic excitotoxicity) for the treatment of AD has been introduced into clinical practice over the past 20 years. Of interest are the data obtained in new studies of Akatinol memantine, which suggest that the latter is able to some extent affect the main pathophysiological processes underlying the development of cognitive impairment in Alzheimer-type pathology.

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Up to 16–20% of patients with a history of traumatic brain injury (TBI), regardless of its severity, suffer from pronounced spasticity, cognitive, vestibular and motor disorders. At the same time, data on the effectiveness of botulinum neurotoxin (BoNT) in the treatment of post-traumatic spasticity is lacking.Objective: to assess the effectiveness of peripheral myorelaxants (botulinum neurotoxin type A) in the treatment of past-traumatic spasticity.Patients and methods. 21 male patients aged 25 to 48 years with post-traumatic spastic hemiparesis (at least 6 months after the injury) were examined. 450 to 850 U (mean – 650 U) of BoNT (incobotulinumtoxin) was injected into the spastic muscles of the upper and lower extremities. The follow-up assessment of spasticity and paresis was performed 24±3 days after BoNT injection. Patterns of spasticity were studied: shoulder adduction, elbow joint flexion, forearm pronation, hand and finger flexion, hip adduction, shin flexion, foot flexion, toe flexion. The following methods were used: original methods of manual testing (MMT) of spasticity, Tardieu scale (TS), modified Ashworth scale (MAS), Medical Research Council Scale (MRCS) to assess paresis.Results and discussion. 24±3 days after incobotulotoxin administration, we observed a significant 1.5–2-fold decrease in spasticity angle (xS) and a reduction in the angle of neuromuscular reactivity (xV3) by 15–30° in all the studied patterns. Changes of xV1 (muscle extensibility) and xA (muscle strength) were not significant. No adverse reactions were observed. The use of MMT and TS has shown its effectiveness and specificity in the evaluation of spasticity and effectiveness of BoNT, and in the dynamics of muscle condition.Conclusion. The study showed the feasibility of using MMT and TS in the evaluation and assessment of spasticity, as well as the effectiveness and safety of incobotulinumtoxin (Xeomin) in dosages from 450 to 850 U in the treatment of spasticity of the upper and lower extremities in patients with the consequences of TBI.