Simulation of endothelium-dependent vasodilation in young male persons based on the parameters of body weight components

The aim of the work. To analyze the results of endothelium-dependent vasodilation of the brachial artery in persons with different content of body weight components and to develop models for predicting the response of endothelium-dependent vasodilation based on the parameters of body weight components. Materials and methods. In total, 31 young men were examined and divided into three groups depending on the total body fat value: 16 people (51.6 %) – group I, 11 people (35.5 %) – group II and 4 people (12.9 %) – group III. Determination of such parameters as body mass index (BMI, kg/m2), the percentage of total fat (TFP, %), the visceral fat content (VFC, units) and the content of free-fat mass (FFM,%) was performed using a bioimpedance analyzer TANITA BC-601. Endothelial regulation was assessed on the basis of vasomotor dilation of the brachial artery activity before and after the occlusion test using a four-channel rheograph ReoCom (XAI-MEDICA). Results. During the occlusion test, three types of endothelium-dependent vasodilation (EDVD) were identified in individuals exa­mined. 62.50 % of men in group I had a normoergic reaction of the brachial artery, 31.25 % had a hyperergic and 6.25 % had a hypoergic reaction. Among group II persons, a normoergic type of post-occlusive reaction was in 45.4 %, hyperergic – in 36.4 %, and hypoergic type – in 18.2 %. Regarding group III, 75 % of individuals had the hyperergic type of endothelium-dependent vasodilation, 25 % had the normoergic type, and no hypoergic type of reaction was observed at all. To determine the endothelial vasoregulatory function on the basis of correlation-regression analysis, models were constructed with coefficients of determination R2 of 0.277 (BMI), 0.126 (TFP), 0.189 (VFC) and 0.146 (FFM). The models themselves had the following form: between EDVD and BMI – y = -4.5297 + 0.865x; TFP – y = 10.7389 + 0.4x; VFC – y =13.8119 + 1.0041x; FFM – y = 52.7904 – 0.4464x. In addition, statistically significant correlations were found between them – from r = +0.335 to r = +0.526. Conclusions. The data obtained allow us to note that the functional state of the endothelium and its activity depends on the content of body weight components in the organism.

Microcirculation Disorders in Patients with Severe COVID-19

Impaired microcirculation due to endothelial dysfunction in COVID-19 is considered to be the most important link in the pathogenesis of this disease. However, due to the complexity of its instrumental assessment in critically ill patients, the data available in the literature on specific manifestations of endothelial dysfunction are very contradictory.The objective: to determine the most characteristic capillaroscopic signs of microvascular disorders and to assess the state of microcirculation regulation in patients with severe COVID-19.Subjects and Methods. When admitted to the intensive care unit, 60 patients with COVID-19 and 12 patients with chronic cardiovascular pathology without COVID-19 (Comparison Group) were examined. All patients underwent microscopy of the microcirculatory bed of finger nail bed; the following parameters were assessed: diameters of the venous, arterial and transitional parts of capillaries, height of capillary loops, density of capillaries per 1 mm of the length of the perivascular zone, the average linear velocity of capillary blood flow (LVCBF), and thickness of the perivascular zone. The presence of avascular zones, the number of capillaries in the visualized field with circulating aggregates in the lumen, and the shape of capillaries were taken into account. In addition, an occlusion test using laser Doppler flowmetry was performed in 32 patients with COVID-19. The maximum post-occlusive increase in blood flow at the moment of cuff deflation was assessed, as well as changes in the mean value of post-occlusive blood flow relative to the baseline within 3 minutes after cuff deflation.Results. In 53 (88.3%) patients with COVID-19, abnormalities corresponding to chronic microcirculatory changes in the form of predominance of pathological capillary forms were detected. Microaggregates in the lumen of capillaries and decreased linear velocity of blood flow were revealed in 100% of cases. When comparing groups of patients with different outcomes, statistically significant differences were revealed between the LVCBF parameters (in the survivors - 354.35 ± 44.78 pm/sec, in the deceased - 278.4 ± 26.59 pm/sec), as well as between the values of the perivascular zones thickness (95.35 ± 15.96 microns versus 159.93 ± 19.90 microns). The results of the post-occlusion test revealed a significant difference between the groups in terms of the maximum post-occlusion gain (39.42 ± 3.85 BPU in the group with a favorable outcome, 27.69 ± 3.19 BPU in the group with an unfavorable outcome, 47.23 ± 1.78 BPU in the control group). In both groups, there was no increase in this parameter relative to the initial blood flow. At the same time, in the control group, the average index of post-occlusive blood flow was higher than the initial level.Conclusions. Acute microcirculation disorders with decreased linear velocity of capillary blood flow, circulation of aggregates, increased thickness of the perivascular zone were detected in all patients with severe COVID-19 but especially in those with unfavorable outcomes. Vascular tone regulation disorders were manifested by the absence of reactive hyperemia in response to acute ischemia, as well as a decrease in maximal flow-induced increase. These changes fit into the concept of endothelial dysfunction. Signs of chronic microcirculation disorders in most patients increase the risk of severe COVID-19.

Bioreactance reliably detects preload responsiveness by the end-expiratory occlusion test when averaging and refresh times are shortened

Background The end-expiratory occlusion (EEXPO) test detects preload responsiveness, but it is 15 s long and induces small changes in cardiac index (CI). It is doubtful whether the Starling bioreactance device, which averages CI over 24 s and refreshes the displayed value every 4 s (Starling-24.4), can detect the EEXPO-induced changes in CI (ΔCI). Our primary goal was to test whether this Starling device version detects preload responsiveness through EEXPO. We also tested whether shortening the averaging and refresh times to 8 s and one second, respectively, (Starling-8.1) improves the accuracy of the device in detecting preload responsiveness using EEXPO. Methods In 42 mechanically ventilated patients, during a 15-s EEXPO, we measured ∆CI through calibrated pulse contour analysis (CIpulse, PiCCO2 device) and using the Starling device. For the latter, we considered both CIStarling-24.4 from the commercial version and CIStarling-8.1 derived from the raw data. For relative ∆CIStarling-24.4 and ∆CIStarling-8.1 during EEXPO, we calculated the area under the receiver operating characteristic curve (AUROC) to detect preload responsiveness, defined as an increase in CIpulse ≥ 10% during passive leg raising (PLR). For both methods, the correlation coefficient vs. ∆CIpulse was calculated. Results Twenty-six patients were preload responders and sixteen non preload-responders. The AUROC for ∆CIStarling-24.4 was significantly lower compared to ∆CIStarling-8.1 (0.680 ± 0.086 vs. 0.899 ± 0.049, respectively; p = 0.027). A significant correlation was observed between ∆CIStarling-8.1 and ∆CIpulse (r = 0.42; p = 0.009), but not between ∆CIStarling-24.4 and ∆CIpulse. During PLR, both ∆CIStarling-24.4 and ∆CIStarling-8.1 reliably detected preload responsiveness. Conclusions Shortening the averaging and refresh times of the bioreactance signal to 8 s and one second, respectively, increases the reliability of the Starling device in detection of EEXPO-induced ∆CI. Trial registration: No. IDRCB:2018-A02825-50. Registered 13 December 2018.

Single stage Large LR recession with or without MR resection and its motor outcomes in Concomitant Exotropia

Exotropia is a manifest outward deviation of the visual axes, which is either constantly or intermittently present. Untreated, poorly controlled intermittent exotropia later progresses to constant exotropia. Sensory exotropia is unilateral divergent misalignment of the eyes, resulting from loss of vision or long-standing poor vision in an eye. In sensory exotropia the angles are characteristically large, ranging from 30 to 100 prism dioptres (PD) and increases gradually over time as long as the cause of visual deficit remains active. Treatment is directed to re-establish the normal ocular alignment and binocular vision[1]. The preferred treatment for manifest exotropia is surgery[2]. Large angle constant exotropia negatively impacts the way the patients see themselves and are perceived by others. The benefits of surgical treatment of exotropia in adults is well proven, both psychologically and visually. The surgical treatment for largeangle exotropia has been a subject of sufficient debate. A variety of surgical plans have been described including two, three or four horizontal rectus muscles recession and resections with or without adjustable suture technique.[3] In more recent studies, the management of large-angle exotropia falls into two surgical approaches. Large bilateral lateral rectus recession is done when the acuity is good in each eye and indicated for true divergent excess type. For basic exodeviation R-R procedure is done popularly. Before embarking on surgical plan we do post occlusion test and identify the clinical type. If one eye is amblyopic, a maximal or supramaximal unilateral recess- resect procedure is performed. Records of previous studies have shown that monocular surgery had shown good results for exotropia of < 60 PD. But for exotropia of > 60 PD, monocular surgery was not so effective (4). In previous studies mild to moderate LR recessions were described but our study involves maximum recession on LR. In previous studies large LR recessions were reported to have complications like Lid changes and palpebral aperture widening. This study was done to evaluate the outcome of single stage, unilateral large LR recession with or without MR resection for constant exotropia

Ciphertext-only attacks on the double random-phase encryption based on redundancy vulnerability

Background: The double random phase encoding techniques have received considerable attention from researchers in recent years because of its advantages of parallel and high speed processing capability. Meanwhile, the security of cryptosystem is also one of the major concerns. Methods : We experimentally demonstrated the ciphertext redundancy vulnerability of the coherent double random encryption system (DRPE). Based on the statistical ergodicity of speckles and the consistency of the power spectral density (ESD), we have proved that the most plaintext information can be retrieved from partial ciphertext alone. Results: In this paper, the simulation and experiment result were performed to verify whether the algorithm is effectiveness. The ciphertext redundancy of the DRPE system is analyzed from the results of ciphertext occlusion test. There is a risk of plaintext leakage of this scheme, as long as the average ESD can be estimated from the sub-images. The results will help to open up deeper understanding of limitation of current optical security techniques. Conclusions: The DRPE system has potential redundancy risk. Even one-time-pad manner is not secured in DRPE system. This vulnerability allows a cryptanalyst to estimate the plaintext information with only a half or less ciphertext.