Evaluation of the Fractional Flow Reserve by Computer Tomography Data: Comparison of the Calculated Parameters with the Results of Invasive Measurements.

Aim      To create a three-dimensional mathematical model of coronary flow in patients with ischemic heart disease based on findings of computed tomography angiography (CTA) with subsequent calculation of the fractional flow reserve (FFRCTA) and comparison of estimated FFRCTA with FFR reference values measured by coronary angiography (CAG).Material and methods  The study included 10 patients with borderline stenosis (50-75 %) as determined by CTA performed with a 640­slice CT-scanner. Based on CTA findings, three-dimensional mathematical models were constructed for further calculation of FFRCTA. Later, an invasive measurement of FFR (FFRINV) was performed for all patients. FFR values <0.8 indicated the hemodynamic significance of stenosis.Results FFRCTA and FFRINV values differed insignificantly in most cases (n=9) and exceeded 5% in only one case. The regression analysis showed a close correlation between estimated and invasively measured FFR values.Conclusion      Preliminary results showed a good consistency of calculated and measured FFR values. Therefore, further development of the method for mathematical modeling of three-dimensional blood flow by CTA findings is promising. Noninvasive evaluation of FFR is particularly relevant for analysis of hemodynamic significance of borderline (50-75 %) coronary stenoses.

EXPERIMENTAL STUDY OF NEW TECHNIQUES IN MODELLING OF ACUTE ADHESIVE SMALL BOWEL OBSTRUCTION.

The aim of our research was the elaboration of acute adhesive small bowel obstruction model and further study of pathomorphological changes of small bowel and peritoneum in experiment. The study was carried out on 40 rats which were done suturing of sero-serous small bowel stiches and modelling of angulations of small bowel with the use of mechanical and implantation factors of peritoneal adhesive disease development according to the worked out by us technique. The suggested experimental model allows modelling the acute adhesive small bowel obstruction just on the 3rd day of the experiment and specifying some aspects of adhesion formation in peritoneum under pathomorphological study.

Structure-Property Relationships in Graphene-Based Strain and Pressure Sensors for Potential Artificial Intelligence Applications.

Wearable electronic sensing devices are deemed to be a crucial technology of smart personal electronics. Strain and pressure sensors, one of the most popular research directions in recent years, are the key components of smart and flexible electronics. Graphene, as an advanced nanomaterial, exerts pre-eminent characteristics including high electrical conductivity, excellent mechanical properties, and flexibility. The above advantages of graphene provide great potential for applications in mechatronics, robotics, automation, human-machine interaction, etc.: graphene with diverse structures and leverages, strain and pressure sensors with new functionalities. Herein, the recent progress in graphene-based strain and pressure sensors is presented. The sensing materials are classified into four structures including 0D fullerene, 1D fiber, 2D film, and 3D porous structures. Different structures of graphene-based strain and pressure sensors provide various properties and multifunctions in crucial parameters such as sensitivity, linearity, and hysteresis. The recent and potential applications for graphene-based sensors are also discussed, especially in the field of human motion detection. Finally, the perspectives of graphene-based strain and pressure sensors used in human motion detection combined with artificial intelligence are surveyed. Challenges such as the biocompatibility, integration, and additivity of the sensors are discussed as well.

COMPLEX DIAGNOSIS OF AN ACUTE ILEUS.

Results of examination and treatment in 256 patients, suffering an acute ileus (AI), were analyzed. Differentiation­diagnostic program was elaborated, what have permitted to establish a correct diagnosis in 98.4% patients. Higher informativity of ultrasonograph' ic investigation, permitting to verify the diagnosis on early stage of the disease and to estimate conservative treatment efficacy, accordingly, in 94.4 and 87.8% patients, was established while doing comparative analysis of ultrasonographic and radiological diag' nostic methods.

[Hepatic dysfunction correction in patients with obturation jaundice].

Comparative analysis of results of examination and treatment of 54 patients, suffering obturation jaundice syndrome, is presented. The presence and severity of hepatic dysfunction was determined in accordance to indices of cytolysis and cholestasis syndromes, and its severity--in accordance to V. P. Zinevich criteria (1986). There was established, that timely elimination of obturation jaundice, using miniinvasive interventions and subsequent conduction of complex hepatotropic therapy, using L-ornitin L-aspartate, permits to correct hepatic dysfunction effectively.

[Unsolved issues of classification of mechanical jaundice].

Basing on analysis of results of examination and treatment of 160 patients, suffering mechanical jaundice, its practical classification was elaborated, containing the issues of pathogenesis and the main characteristics according to anatomo-topographic and clinical criteria.

[Criteria of diagnosis and principles of treatment of obturation jaundice and its complicated forms--an acute cholangitis and biliary sepsis].

Analysis of the examination and treatment results was conducted in 92 patients, suffering the obturation jaundice syndrome. There was elaborated a diagnostic program, in which the existing diagnostic standard for obturation jaundice and its complicated forms, an acute cholangitis and biliary sepsis, was added by determination of the blood procalcitonin level, microbiological investigation of the blood and bile, the bile microscopy, the analysis of the system inflammatory response syndrome signs and the organs dysfunction (according to SOFA scale). The program introduction have permitted to perform differential diagnosis of uncomplicated--in 30 (32.6%) patients, and complicated--in 42 (45.7%) obturation jaundice in an acute cholangitis and in 20 (21.7%)--in biliary sepsis. The treatment program is characterized by differentiated approach, depending on the disease kind, and includes the conduction of urgent decompression and sanation of biliary ducts. The method and volume of complex conservative therapy have differed essentially in patients, suffering obturation jaundice, an acute cholangitis and biliary sepsis.

[Myocardial responses to ischemia].

The paper details the types of a myocardial response to impaired blood flow, such as myocardial stunning, hibernation, ischemic preconditioning, warm-up phenomenon, ischemic postconditioning, remodeling, and infarction. According to the pathogenesis, the authors identify several types of myocardial dysfunction in transient ischemic attack--uptake, delivery; and a mixed one. It is concluded the myocardial response to damage depends on a combination of influencing factors, a number of pathophysiological processes starting in the acute phase of ischemia achieve its peak in the late period.

Electronic and magnetic properties of Mn-doped BeSiAs(2) and BeGeAs(2) compounds.

The structural, electronic and magnetic properties of BeSiAs(2) and BeGeAs(2) chalcopyrite ternary compounds doped with manganese were investigated by means of ab initio calculations. It was found that substitution of Be atoms by Mn increases the lattice constants of both compounds that provide acceptable mismatch with conventional Si, Ge and GaAs substrates. In spite of the increase of the spin polarization upon doping, both compounds possess antiferromagnetic (AFM) ordering with the impurity in the group II position whereas ferromagnetic (FM) ordering is obtained in the case of an impurity in the group IV position.

[Dynamics of charge carrier transfer in a DNA molecule].

An equivalent electric circuit has been developed which describes the charge transfer in DNA molecule. A computer simulation of the charge carrier transfer dynamics in the molecule has been performed based on this circuit. It was found that the switching time of a molecular junction lies in the femtosecond range and depends on the frequency of the input electric signal. An increase in the frequency of the input signal in the range from 1 GHz to 4 THz and a reduction of temperature lead to a decrease in the current passing through the DNA molecule. It has been shown that the sequence of the DNA base pairs defines the rate of localization and delocalization of holes and controls the signal propagation rate in the DNA molecule.

[The role of structural reorganization in charge carrier transfer in DNA molecule].

A model of hole transfer in DNA molecules has been proposed, which takes into account changes in the reorganization energy and orbital coupling between the neighboring bases during the charge transfer in different molecular sequences. It is shown that the rate of hole transfer by the superexchange and hopping transfer mechanisms is limited by the relaxation of the geometries of nucleobases participating in charge migration and the dynamics of solvent molecules. The rate of charge transfer in the DNA molecule is found to be dependent on the height of the potential barriers between the nucleotide and the molecular sequences. The inclusion of the interchain charge transfer, which is characterized by weak coupling between the nucleotides located in opposite strands, does not affect the general charge transport in DNA. The increase in the number of the parallel components of the hopping mechanism leads to a rise in the charge transfer rate in the double helix.

Simultaneous optical and electrical recording of single gramicidin channels.

We report here an approach for simultaneous fluorescence imaging and electrical recording of single ion channels in planar bilayer membranes. As a test case, fluorescently labeled (Cy3 and Cy5) gramicidin derivatives were imaged at the single-molecule level using far-field illumination and cooled CCD camera detection. Gramicidin monomers were observed to diffuse in the plane of the membrane with a diffusion coefficient of 3.3 x 10(-8) cm(2)s(-1). Simultaneous electrical recording detected gramicidin homodimer (Cy3/Cy3, Cy5/Cy5) and heterodimer (Cy3/Cy5) channels. Heterodimer formation was observed optically by the appearance of a fluorescence resonance energy transfer (FRET) signal (irradiation of Cy3, detection of Cy5). The number of FRET signals was significantly smaller than the number of Cy3 signals (Cy3 monomers plus Cy3 homodimers) as expected. The number of FRET signals increased with increasing channel activity. In numerous cases the appearance of a FRET signal was observed to correlate with a channel opening event detected electrically. The heterodimers also diffused in the plane of the membrane with a diffusion coefficient of 3.0 x 10(-8) cm(2)s(-1). These experiments demonstrate the feasibility of simultaneous optical and electrical detection of structural changes in single ion channels as well as suggesting strategies for improving the reliability of such measurements.

[Experience of surgical treatment of the patients with post-burn cicatricial gastric stenosis]. / Opyt khirurgicheskogo lecheniia bol'nykh s posleozhogovym rubtsovym stenozom zheludka.

Experience of surgical treatment of 48 patients with postburn cicatricial gastric stenosis was presented. In 28 of them the combined gastric and esophageal stricture were reveal. Gastric resection according to Billroth-I was performed in 26 patients, gastroduodenostomy according to Finney--in 4, gastric resection according to Hoffmeister-Finsterer--in 5, gastroenterostomy according to Belfler-Brown--in 10 and other operations--in 3. One patient died. For the treatment of combined stricture esophageal passability was restored using bougienage, optimally--along the ring-like thread-guide, conducted, while performing gastric operation, through the mouth, esophagus, stomach and brought out via microgastrostomy.

[Method of minimally invasive gastrostomy]. / Sposob maloinvazivnoi ("kulisnoi") gastrostomii.

An original variant of minimally invasive gastrostomy is described which is recommended for use in cases of a necessary temporary exclusion of the esophagus passage in patients with lesions of the esophagus in combination with a severe concomitant pathology.

Fluorescent gramicidin derivatives for single-molecule fluorescence and ion channel measurements.

Single-molecule spectroscopies in combination with single-channel patch-clamp measurements have the potential for providing new information on ion channel gating processes. Fluorescent gramicidin derivatives could provide a means for calibrating such experiments since the structure of the open channel is known and the mechanism of gating (peptide dimerization) is generally agreed. We describe here the synthesis and characterization of two pairs of gramicidin derivatives that should prove useful for such studies. They contain robust fluorophores, undergo resonance energy transfer (FRET) when they dimerize, and have single-channel properties close to those of the wild-type channel.

[Iatrogenic esophageal perforation in forcing bougienage of its post-burn cicatricial stricture]. / Iatrogennaia perforatsiia pishchevoda pri forsirovannom buzhirovanii ego posleozhogovoi rubtsovoi striktury.

While performing forceful esophageal bougienage for postburn cicatricial stricture its wall perforation have occurred in 9 of 57 patients. All the patients were operated on. For perforation of thoracic esophagus transabdominal transdiaphragmatic mediastinal drainage was performed and for subdiaphragmatic perforation--closure of the defect with Nissen fundoplication, gastrostomy with temporary conduction of ring--like guide fishing-line. One patient died.

Protonation of lysine residues inverts cation/anion selectivity in a model channel.

A dimeric alamethicin analog with lysine at position 18 in the sequence (alm-K18) was previously shown to form stable anion-selective channels in membranes at pH 7.0 [Starostin, A. V., R. Butan, V. Borisenko, D. A. James, H. Wenschuh, M. S. Sansom, and G. A. Woolley. 1999. Biochemistry. 38:6144-6150]. To probe the charge state of the conducting channel and how this might influence cation versus anion selectivity, we performed a series of single-channel selectivity measurements at different pH values. At pH 7.0 and below, only anion-selective channels were found with P(K(+))/P(Cl(-)) = 0. 25. From pH 8-10, a mixture of anion-selective, non-selective, and cation-selective channels was found. At pH > 11 only cation-selective channels were found with P(K(+))/P(Cl(-)) = 4. In contrast, native alamethicin-Q18 channels (with Gln in place of Lys at position 18) were cation-selective (P(K(+))/P(Cl(-)) = 4) at all pH values. Continuum electrostatics calculations were then carried out using an octameric model of the alm-K18 channel embedded in a low dielectric slab to simulate a membrane. Although the calculations can account for the apparent pK(a) of the channel, they fail to correctly predict the degree of selectivity. Although a switch from cation- to anion-selectivity as the channel becomes protonated is indicated, the degree of anion-selectivity is severely overestimated, suggesting that the continuum approach does not adequately represent some aspect of the electrostatics of permeation in these channels. Side-chain conformational changes upon protonation, conformational changes, and deprotonation caused by permeating cations and counterion binding by lysine residues upon protonation are considered as possible sources of the overestimation.

An anion-selective analogue of the channel-forming peptide alamethicin.

The peptide alamethicin self-assembles to form helix bundle ion channels in membranes. Previous macroscopic measurements have shown that these channels are mildly cation-selective. Models indicate that a source of cation selectivity is a zone of partial negative charge toward the C-terminal end of the peptide. We synthesized an alamethicin derivative with a lysine in this zone (replacing the glutamine at position 18 in the sequence). Microscopic (single-channel) measurements demonstrate that dimeric alamethicin-lysine18 (alm-K18) forms mildly anion-selective channels under conditions where channels formed by the parent peptide are cation-selective. Long-range electrostatic interactions can explain the inversion of ion selectivity and the conductance properties of alamethicin channels.

[Structural-functional interrelations in patients with an epileptic syndrome in posttraumatic hydrocephalus]. / Strukturno-funktsional'nye vzaimosviazi u bol'nykh s épilepticheskim sindromom pri posttravmaticheskoi gidrotsefalii.

Overall forty two patients presenting with epileptic syndrome in posttraumatic hydrocephalus in the remote period of light closed craniocerebral injury, who ranged from 16 to 60 years old, were examined. Degree of severity and variety of posttraumatic hydrocephalus were assessed by findings from axial computerized tomography, pneumoecephalography, magnetoresonance tomography. All patients underwent electroencephalography. The examinees were predominantly those persons presenting with light and internal symmetrical hydrocephalus. 57.2% of patients developed cerebral seizures within the first 5 years of sustaining the injury. Normal EEG was recordable in those patients with epileptic syndrome presenting with light and internal symmetrical hydrocephalus. Apparent diffusive disturbances in the bioelectrical activity of the brain were more common in moderately severe hydrocephalus and in mixed hydrocephalus. The presence of paroxysmal activity is a particular characteristic of patients with epileptic syndrome in outer hydrocephalus. A distinguishing feature of internal asymmetrical hydrocephalus is an observation of a decrease in the general level of biopotentials.