[Screening of patients with cerebral aneurysms: mathematical analysis and economic justification]. / Skrining patsientov s anevrizmami golovnogo mozga: matematicheskii analiz i ekonomicheskoe obosnovanie.

Subarachnoid hemorrhages due to rupture of cerebral aneurysms have a high risk of disability and mortality. Screening of the population to detect aneurysms in patients with risk factors is currently not carried out in Russia. However, the detection of clinically silent aneurysms and their subsequent prophylactic surgical treatment are justified, according to numerous studies. BACKGROUND: Demonstrate the clinical and economic feasibility of screening the population (including first-line relatives) for cerebral aneurysms using an economic and mathematical model of the RF virtual population. MATERIAL AND METHODS: Mathematical modeling was carried out using an algorithm that implements a discrete Markov chain. The virtual population consisted of 145 million people (the population of the Russian Federation). Magnetic resonance angiography 3DTOF was chosen as a screening method. Virtual patients underwent preventive surgical treatment in case of detection of aneurysm during screening. The number of aneurysms in the population, the number of aneurysmal subarachnoid hemorrhage (aSAH), the cost and outcomes of treatment, and the risk of disability were calculated. RESULTS: In the case of screening and preventive surgical treatment of aneurysms, there is a decrease in the number of aSAH by 14.3% (37.5% in first-line relatives (RPLR), which affects the reduction in mortality due to aSAH by 14.4% (24.1% in The total number of disabled people is reduced by 1.5% (5.1% for the RPHR). A shift in the structure of disability towards greater labor and social adaptation of patients was noted. An economic analysis for the entire population showed that screening saves 7.7 billion annually rubles, including in the population consisting of RPLR - 4.9 billion rubles. CONCLUSION: The created mathematical model of the virtual population demonstrated that screening and prophylactic treatment of cerebral aneurysms makes it possible to reduce the number of aSAH and associated mortality among the entire population and in the RPLR group. The number of individuals with severe disabilities is decreasing. Thus, population screening for the detection of cerebral aneurysms may be clinically effective and cost-effective in the general population, especially in RPCR.

[Artificial intelligence guided predicting the length of hospital-stay in a neurosurgical hospital based on the text data of electronic medical records]. / Prognozirovanie dlitel'nosti gospitalizatsii v neirokhirurgicheskoi klinike po tekstovym dannym elektronnoi meditsinskoi dokumentatsii s pomoshch'yu tekhnologii iskusstvennogo intellekta.

BACKGROUND: Rational use of internal resources of hospitals including bed fund turnover is important objective in high-tech medicine. Machine learning technologies can improve neurosurgical care and contribute to patient-oriented approach. OBJECTIVE: To evaluate the quality of AI-guided predicting the length of hospital-stay in a neurosurgical hospital based on the text data of electronic medical records in comparison with expectations of patients and physicians. MATERIAL AND METHODS: AI-guided prediction was based on analysis of unstructured text records of the electronic medical history (preoperative examination and surgical protocol). Predictive models were learned on the data of the Burdenko Neurosurgery Center accumulated for the period 2000-2017 (90.688 cases). Model testing was performed on 111 completed neurosurgical cases in a prospective study. We compared the accuracy of prediction models compared to expectations of patients and physicians regarding hospital-stay. RESULTS: The median absolute error of machine prediction in the final test was 2.00 days. This value was comparable with the doctor's prediction error. CONCLUSION: This study demonstrated the possibility of using unstructured textual data to predict the length of hospital-stay in a neurosurgical hospital.

Non-monotonic variation of the Kramers point band gap with increasing magnetic doping in BiTeI.

Polar Rashba-type semiconductor BiTeI doped with magnetic elements constitutes one of the most promising platforms for the future development of spintronics and quantum computing thanks to the combination of strong spin-orbit coupling and internal ferromagnetic ordering. The latter originates from magnetic impurities and is able to open an energy gap at the Kramers point (KP gap) of the Rashba bands. In the current work using angle-resolved photoemission spectroscopy (ARPES) we show that the KP gap depends non-monotonically on the doping level in case of V-doped BiTeI. We observe that the gap increases with V concentration until it reaches 3% and then starts to mitigate. Moreover, we find that the saturation magnetisation of samples under applied magnetic field studied by superconducting quantum interference device (SQUID) magnetometer has a similar behaviour with the doping level. Theoretical analysis shows that the non-monotonic behavior can be explained by the increase of antiferromagnetic coupled atoms of magnetic impurity above a certain doping level. This leads to the reduction of the total magnetic moment in the domains and thus to the mitigation of the KP gap as observed in the experiment. These findings provide further insight in the creation of internal magnetic ordering and consequent KP gap opening in magnetically-doped Rashba-type semiconductors.

Ring patterns generated by an expanding colloidal meniscus.

The drop-and-dry is a common technique allowing for creation of periodic nanoparticle (NP) structures for sensing, photonics, catalysis, etc. However, the reproducibility and scalability of this approach for fabrication of NP-based structures faces serious challenges due to the complexity of the simple, at first glance, evaporation process. In this work we study the effect of the spatial confinement on the NP self-assembly under slow solvent evaporation, when the air-liquid-substrate contact line (CL) expands from the center towards the walls of a cylindrical cell, forming a toroid. Using in situ video monitoring of the stick-slip CL motion, we find regular hydrodynamic perturbations in the meniscus, and reveal fine details of the formation of quasiperiodic rings of close packed NP layers. We report that drying of the toroidal NP droplet has a number of important differences from drying of the classical hemispherical colloidal drops. In toroidal drops we observe linear-in-time average meniscus motion, in contrast to the hemispherical drops where the meniscus moves as a square root of time. While both droplet geometries produce NP ring patterns, the ring width for the toroidal drop decreases with increasing ring radius, while it decreases with decreasing the radius of the hemispherical drop. We suggest that free ligands are the main cause of the Marangoni instabilities driving the periodic vorticity in the meniscus. In addition, we show that the usually ignored contact line tension may yield a considerable contribution to the CL pinning causing the CL slip-stick motion and the ring formation.

[A 20-year experience in surgical treatment of steno-occlusive lesion of craniocervical arteries at the Burdenko Neurosurgical Center]. / Dvadtsatiletnii opyt khirurgicheskogo lecheniya stenoziruyushchei i okklyuziruyushchei patologii brakhiotsefal'nykh arterii v FGAU «Natsional'nyi meditsinskii issledovatel'skii tsentr neirokhirurgii im. akad. N.N. Burdenko¼.

INTRODUCTION: Surgical treatment of cerebral ischemia at the Burdenko Neurosurgical Center for the period from 1999 to 2019 is analyzed in the paper. The details of the treatment strategy in patients with steno-occlusive lesion of craniocervical arteries followed by cerebral ischemia developed over 20 years are discussed in the article. We have analyzed the features of surgical interventions on the major craniocervical arteries in a neurosurgical clinic and the results of this treatment. OBJECTIVE: To demonstrate management of various lesions of major cerebral arteries in modern neurosurgical vascular hospital. MATERIAL AND METHODS: In total, there were 3098 interventions on the major cerebral arteries in 2527 patients for this period. Mean age of patients ranged from 1.5 to 91 years (58±14 years). Interventions included open reconstructions of the carotid arteries (2031 surgeries), reconstructions of the vertebrobasilar arteries (135 surgeries), brain revascularization (658 surgeries), excision of the tumors of neurovascular bundle on the neck compressing carotid arteries (51 interventions). Endovascular interventions were performed in 223 cases and consisted of angioplasty and stenting of the extracranial segments of craniocervical arteries (185 surgeries), stenting of the intracranial arteries (30 surgeries) and endovascular thrombextraction (8 cases). Staged surgeries were performed in 541 patients (22.3%). RESULTS: Favorable outcomes were obtained in 87.6% of cases, satisfactory results - in 9% of patients. Clinical deterioration due to long-term postoperative complications and recurrent strokes occurred in 2.9% of cases. Postoperative morbidity rate was 4.6%, persistent neurological deficit developed in 2.6% of cases. Mortality rate was 0.5%. CONCLUSION: Surgical treatment of stenotic and occlusive lesion of the major cerebral arteries is an interdisciplinary problem. Solution of this issue is closely associated with technological progress, new discoveries in normal and pathological physiology, as well as clinical researches. Individualized choice of surgical approach is one the main modern trends of neurosurgical approach to this problem. At the same time, own surgical experience is the most important factor determining the results of arterial reconstructions.

[The use of amantadine sulfate in ischemic stroke]. / Primenenie amantadina sul'fata pri ishemicheskom insul'te.

OBJECTIVE: To assess the efficacy and safety of amantadine sulfate in patients with ischemic stroke. MATERIAL AND METHODS: Ninety five patients with ischemic stroke were randomized within 120 hours from the onset of symptoms into two groups: patients of the main group received amantadine sulfate (400 mg/day intravenously) for 4 days, followed by oral administration at 400 mg/day for 6 days; the comparison group received standard therapy according to the order of the Ministry of Health of the Russian Federation No. 928n. The observation period for the patients was 90 days. The main indicators of treatment efficacy were: Glasgow Coma Scale (GCS), Modified Rankin Scale (mRS), Bartel Index (BI), National Institutes of Health Stroke Scale (NIHSS), and mortality. Any side effects were recorded to assess safety. RESULTS AND CONCLUSION: There were no statistically significant differences between the main group and the comparison group for the main parameters. However, we observed better results in patients with mild stroke (NIHSS <13 points) and atherothrombotic pathogenetic variant of ischemic stroke. This observation should be confirmed in subsequent clinical studies.

[Local cerebral hemodynamics following STA-MCA bypass in patients with symptomatic carotid occlusions]. / Lokal'naia gemodinamika posle sozdaniia ÉIKMA u patsientov s simptomaticheskimi okkliuziiami sonnykh arterii.

PURPOSE: To assess changes in local hemodynamic parameters in patients with symptomatic ICA occlusions and moyamoya disease after placement of extracranial-intracranial bypass (EC-IC bypass). MATERIAL AND METHODS: The study included 112 patients who underwent surgical treatment at the National Scientific and Practical Center for Neurosurgery in the period between 1999 and 2015. Of these, 105 patients had ICA occlusions, and 7 patients had moyamoya disease. During the main stage of EC-IC bypass placement, all patients were monitored for local hemodynamic parameters using intraoperative contact Doppler ultrasonography - 89 (72%) patients (72%) and flowmetry - 56 (50%)). In 33 (29%) cases, both techniques were used. Forty two patients underwent preoperative SCT perfusion to assess the degree of perfusion deficit. Grade 1 cerebrovascular insufficiency (acute oligemia) was detected in 6 patients; grade 2 perfusion deficit (persistent oligemia) was found in 25 patients; grade 3 perfusion deficit (chronic oligemia) was present in 11 patients. Measurements were performed before bypass placement: the blood flow direction and hemodynamic parameters in the cortical arteries were evaluated; and after bypass placement: blood flow values and directions in the cortical artery, proximal and distal to the bypass area, were assessed. RESULTS: A total of 112 EC-IC bypasses were placed without perioperative complications and deaths. Bypass functioning was confirmed in 108 (96.3%) cases; bypass thrombosis occurred in 4 (3.7%) cases. The distal blood flow direction was observed in patients with ICA occlusions (105 patients) in all cases before EC-IC bypass placement. Patients with moyamoya disease had more often the proximal blood flow direction - 5 (71%) out of 7 cases. The cerebral blood flow parameters obtained in this study differed significantly, depending on the baseline degree of perfusion deficit. The blood flow rate was minimal in patients with grade 1 cerebrovascular insufficiency. After revascularization, local hemodynamics in the cortical arteries was significantly dependent on the ability of EC-IC bypass to reverse blood flow in the proximal acceptor artery. A change in the blood flow direction was observed in 86 (77%) cases. The mean volumetric blood flow in EC-IC bypass was 34.2±5.7 mL/min. CONCLUSION: The knowledge of baseline hemodynamic parameters and their changes after revascularization plays an important role in choosing the correct surgical technique, further bypass functioning, and, as a result, improvement of the clinical outcome after surgery.

Dirac gap opening and Dirac-fermion-mediated magnetic coupling in antiferromagnetic Gd-doped topological insulators and their manipulation by synchrotron radiation.

A new kind of magnetically-doped antiferromagnetic (AFM) topological insulators (TIs) with stoichiometry Bi1.09Gd0.06Sb0.85Te3 has been studied by angle-resolved photoemission spectroscopy (ARPES), superconducting magnetometry (SQUID) and X-ray magnetic circular dichroism (XMCD) with analysis of its electronic structure and surface-derived magnetic properties at different temperatures. This TI is characterized by the location of the Dirac gap at the Fermi level (EF) and a bulk AFM coupling below the Neel temperature (4-8 K). At temperatures higher than the bulk AFM/PM transition, a surface magnetic layer is proposed to develop, where the coupling between the magnetic moments located at magnetic impurities (Gd) is mediated by the Topological Surface State (TSS) via surface Dirac-fermion-mediated magnetic coupling. This hypothesis is supported by a gap opening at the Dirac point (DP) indicated by the surface-sensitive ARPES, a weak hysteresis loop measured by SQUID at temperatures between 30 and 100 K, XMCD measurements demonstrating a surface magnetic moment at 70 K and a temperature dependence of the electrical resistance exhibiting a mid-gap semiconducting behavior up to temperatures of 100-130 K, which correlates with the temperature dependence of the surface magnetization and confirms the conclusion that only TSS are located at the EF. The increase of the TSS's spectral weight during resonant ARPES at a photon energy corresponding to the Gd 4d-4f edge support the hypothesis of a magnetic coupling between the Gd ions via the TSS and corresponding magnetic moment transfer at elevated temperatures. Finally, the observed out-of-plane and in-plane magnetization induced by synchrotron radiation (SR) due to non-equal depopulation of the TSS with opposite momentum, as seen through change in the Dirac gap value and the k∥-shift of the Dirac cone (DC) states, can be an indicator of the modification of the surface magnetic coupling mediated by the TSS.

[Simultaneous reconstruction of the carotid and vertebral arteries using a temporary intraluminal shunt (a clinical case)]. / Odnomomentnaia rekonstruktsiia sonnoi i pozvonochnoi arterii s ispol'zovaniem vremennogo vnutriprosvetnogo shunta (klinicheskoe nabliudenie).

The article describes a case of one-stage surgical treatment of a patient with progressive chronic cerebral ischemia caused by combined steno-occlusive lesions of the carotid and vertebral arteries. The disease was complicated by intolerance to temporary occlusion of the carotid artery due to an incomplete circle of Willis. We performed extra-anatomic carotid-vertebral artery bypass with subsequent ipsilateral carotid endarterectomy. A temporary intraluminal shunt was used at the main stage of reconstructive surgery. We use this clinical case to analyze the issues of surgical treatment for combined lesions of the carotid and vertebral arteries and the techniques for prevention of associated ischemic complications.

[Criteria of the efficacy of surgical brain revascularization in patients with chronic cerebral ischemia].

PURPOSE: The article analyzes results of surgical revascularization in patients with symptoms of chronic cerebral ischemia caused by occlusion of the carotid arteries. MATERIAL AND METHODS: We analyzed 404 surgeries for placement of extra-intracranial microvascular anastomoses (EICMAs) performed in 376 patients between 2000 and 2015. All patients underwent detailed neurological and neuropsychological examinations before surgery and throughout the follow-up period using the neurological deficit scale (NIHSS). Additionally, the medical history data, technical features of surgery, and results of instrumental tests were recorded. For a more detailed study of the cerebral circulation, a SCT perfusion examination was conducted in 58 patients before and after placement of EICMA. RESULTS: All patients were divided into 3 groups, depending on the surgical treatment outcomes: improvement (53%), without significant changes (43%), and worsening of clinical symptoms (4%). A statistical analysis revealed that the efficacy of EICMA surgery ranged from 22 to 79% and was reliably confirmed by hemodynamic and anamnestic factors as well as by technical details of surgery. CONCLUSION: When determining the indications for surgical revascularization in patients with ischemic stroke consequences, the patient's age, occlusion duration, location and size of ischemic lesions should be considered. Also, the choice of the acceptor artery and blood flow through the created anastomosis are of great importance.

[Increase in NK-activity using superlow doses of the immunomodulator cycloferon]. / Povyshenie EK-aktivnosti s pomoshch'iu sverkhmalykh doz immunomoduliatora tsikloferona.

A possibility of rising the antitumor activity of natural killers using various doses of the immunomodulator cycloferon was evaluated. A direct correlation has been revealed between the killer activity and the cycloferon dose. However, on a decrease in cycloferon concentrations by several orders, as compared with commonly accepted doses, this correlation changed for inverse. A possible mechanism of this effect is discussed in addition to practical significance of the obtained results.

[Polymyxin B and Ca(2+) induce conductance fluctuations in the dipalmitoyl phosphatidic acid bilayer lipid membrane]. / Polimiksin B i Ca(2+) indutsiruiut fluktuatsii provodimosti v bisloinoi lipidnoi membrane iz dipal'mitoilfosfatidnoi kisloty.

Polymyxin B in micromolar concentrations induces current fluctuations in liquid crystalline bilayer lipid membranes from dipalmitoylphosphatidic acid identified as ion channels. The appearance of ion channels correlates with phase separation of the lipid in the presence of peptide polycations detected by differential scanning calorimetry. Ca2+ also induces the formation of ion channels in liquid crystalline bilayer lipid membranes from dipalmitoylphosphatidic acid followed by the phase transition of the phospholipid. The capacitive current, which indicates the possibility of structural transformations of bilayer-non-bilayer type (hexagonal phase II), precedes the formation of Ca(2+)-induced channels in bilayer lipid membranes from dipalmitoylphosphatidic acid.

[Lipid pores and life time of lipid bilayer membranes in gel and liquid crystal states]. / Lipidnye pory i vremena zhizni bisloinykh lipidnykh membran v gel'- i zhidkokristallicheskom sostoianiiakh.

The lifetime of lipid bilayer membranes formed from hydrogenated egg lecithin has been studied at the phase transition from liquid crystalline state to the gel. It was shown the lowering of the membrane stability at the phase transition temperature of hydrogenated egg lecithin. Using lifetime values and measured surface tension of bilayer the critical radius of transmembrane pore has been evaluated in comparison with experimental data, obtained by transmembrane current fluctuation registration. It was shown that lifetimes of bilayer lipid membrane in gel state conform data, derived from Deryagin-Gutop-Prokhorov's theory. The radii of pores corresponded to maximal transmembrane current fluctuations are close to critical values of pores in the gel state.

[Lipid pores and stability of cell membranes]. / Lipidnye pory i stabil'nost' kletochnykh membran.

Electric studies have ascertained that transmembrane pores appear during the gel-liquid crystalline transition phase in the bilayer lipid membrane. The longevity of the pore depends on the phase state of lipids: in gel, the pores demonstrate long-term fluctuations, which can be eliminated by heating. The molecular model of a lipid pore has been proposed. The model predicts the formation of pores whose appearance is energetically favourable. The size of a cooperative unit and the area per lipid molecule head have been shown to be responsible for membrane stability. Proceeding from the model, a hypothesis has been forwarded that phase transition may be induced in the lipid bilayer at physiological temperatures. Electric techniques and differential scanning calorimetry have established that bivalent ions of Ca2+, Cd2+, Mg2+, Sr2+, and Ba2+ are able to induce phase transition of bilayer membranes from acid lipids at physiological temperatures to give rise to through pores. An analysis of the experimental findings indicates that pores having a less critical radius themselves adhere with time.

[Formation of stabile cupola-like lipid bilayer membranes with a mobile plateau Gibbs boundary]. / Formirovanie stabil'nykh kupoloobraznykh bisloinykh lipidnykh membran s podvizhnoi granitsei plato-Gibbsa.

Stable bilayer lipid membrane with mobile Platear-Gibbs border have been formed. The predominant condition of the formation is the presence of lipid coverage on the teflon surface near the hole. The formation process includes transformation of the initial planar lipid bilayer into cupola-shaped one by bowing of the lipid bilayer due to hydrostatic pressure, movement of the PGb along the teflon surface. The bilayer area estimated by electric capacitance increases from 0.1 x 10(-8) F to 21 x 10(-8) F. Electric conductance of the lipid bilayer has not changed except for the phase transition and membrane collapse. The electric capacitance of the BLM formed from hydrogenated egg lecithin was changed by cooling between 60 degrees and 40 degrees C with the maximum at about phase transition range. The individual membrane sustains several scannings of the temperature without disruption which is an evidence of the stability of the cupola-shaped membranes.

Stable cupola-shaped bilayer lipid membranes with mobile Plateau-Gibbs border: expansion-shrinkage of membrane due to thermal transitions.

Stable bilayer lipid membranes (BLM) with mobile Plateau-Gibbs border (PGB) have been formed. The precondition of the formation was the presence of a lipid coverage on the teflon surface near the hole, where the membrane has been formed. This allowed the movement of the PGB along the teflon surface after transformation of the planar bilayer into a cupola-shaped by bowing of the bilayer due to excess hydrostatic pressure. As a result the giant bilayers were obtained with an area up to two orders larger in magnitude compared with the initial area. Changes in lipid bilayer area depend on the temperature at the phase transition of the lipid. Cooling of the expanded bilayer was followed by a significant shrinkage of the bilayer at temperatures below the main phase transition.

[Autotransfusions of sorbent blood in treating peptic ulcer patients with an unfavorable course]. / Autotransfuzii sorbentnoi krovi v lechenii bol'nykh iazvennoi bolezn'iu s neblagopriiatnym techeniem.

Autotransfusion of sorbent blood was used in the complex treatment of 62 patients with gastric ulcer characterized by an unfavourable course. The course of autotransfusions favoured scarring of the gastric ulcer in 70.9% of patients, normalized the helper/suppressor relations of regulatory subpopulations of T-lymphocytes, normalized the indices of natural killer activity.