Microcirculatory Changes Research Articles

Experience in the lower extremities trophic ulcers treatment in patient with combined pathologies: varicose veins and rheumatoid arthritis

Varicose veins of the lower extremities is one of the most common diseases on Earth and its combination with other diseases is inevitable. The combination of diseases aggravates the course of each other. Rheumatoid arthritis worsens the course of varicose veins with trophic disorders – both independently – an increase in pro-inflammatory factors, a change in microcirculation, deformation of the limb axis with a violation of musculoskeletal function, and treatment of rheumatoid arthritis reduces the immune response of the body reducing the reparative capabilities of the body. Clinical case: a patient with a long course of rheumatoid arthritis and varicose veins. For a long time he used cytostatic drugs with a subsequent transition to hormonal drugs. For about 5 years, he noted the appearance of ulcers on both shins, which took a circular shape, which significantly reduced the quality of life and did not respond to conservative treatment. He repeatedly underwent inpatient treatment with intravenous administration of general restorative and vascular drugs. He was also constantly observed in the polyclinic at the place of residence with the implementation of local treatment of ulcerative surfaces. The patient was successively treated for varicose veins by endovenous laser coagulation of the trunks of large subcutaneous veins. The second stage was performed debridement of the wound surface and skin grafting with a free perforated flap. Between the stages, the appointment of drug therapy according to clinical recommendations. Rheumatoid arthritis and varicose veins aggravate each other, especially trophic manifestations. Treatment of such patients should be carried out by a team ofspecialists of various profiles together. Step-by-step treatment ofsuch patients with careful preparation for each of them shows excellent results. A special place is occupied by the patients’ commitment to treatment.

Recent Research Progress in Fluorescent Probes for Detection of Amyloid-β In Vivo.

Alzheimer's disease (AD) is a neurodegenerative disease. Due to its complex pathological mechanism, its etiology is not yet clear. As one of the main pathological markers of AD, amyloid-β (Aβ) plays an important role in the development of AD. The deposition of Aβ is not only related to the degeneration of neurons, but also can activate a series of pathological events, including the activation of astrocytes and microglia, the breakdown of the blood-brain barrier, and the change in microcirculation, which is the main cause of brain lesions and death in AD patients. Therefore, the development of efficient and reliable Aβ-specific probes is crucial for the early diagnosis and treatment of AD. This paper focuses on reviewing the application of small-molecule fluorescent probes in Aβ imaging in vivo in recent years. These probes efficiently map the presence of Aβ in vivo, providing a pathway for the early diagnosis of AD and providing enlightenment for the design of Aβ-specific probes in the future.

Modern etiopathogenetic, clinicopathological and therapeutic aspects of lichen planus

Objective — to analyze modern views on the etiopathogenesis, clinical course and approaches to the complex therapy of lichen planus, and to determine promising directions for further research that will contribute to the expansion of ideas about the mechanisms of development and optimization of the treatment of this dermatosis.
 Materials and methods. Based on the analysis of modern data from special literature and according to the results of our own preliminary studies, the expediency of further in-depth studies of the state of microcirculation and microbiocenosis in skin lesions of patients with lichen planus was determined.
 Results and discussion. Violations of microcirculation and changes in microbiocenosis in foci of skin lesions in patients with lichen planus are important links in the pathogenesis of this dermatosis, and can also affect the severity of its clinical course.
 Conclusions. So far, the etiopathogenetic and clinicopathological aspects of lichen planus have been studied in detail, which allows us to evaluate the mechanisms of development, clinical course and approaches to the treatment of this dermatosis in a new way.The state of microcirculation and changes in the microbiocenosis in foci of skin lesions in patients with lichen planus require further in-depth research. The results of our preliminary studies indicate that microcirculation disorders and microbiocenosis changes in the skin lesions of patients with lichen planus affect the nature and severity of the clinical course of this dermatosis.Further in-depth studies of microcirculatory disorders and changes in microbiocenosis in foci of skin lesions in patients with lichen planus will allow to optimize complex therapy and expand the understanding of the pathogenesis of this dermatosis.

The impact of microcirculation improvements of coronary artery flow on macrocirculation after coronary intervention

Abstract Background The impact of microcirculation changes of coronary artery after percutaneous coronary intervention (PCI) and its association with macrocirculation remained obscured. Purpose This study aimed to investigate the impact of microcirculation changes of coronary artery flow on macrocirculation after coronary intervention. Methods This prospective study enrolled patients who underwent PCI. Electrical cardiometry was used for hemodynamics measurement before and after PCI. Deidentified data of patients in this study cohort were analyzed. Moreover, peri-procedural deidentified N-terminal-pro-B type natriuretic peptide level (NT-proBNP) values were analyzed. Results There was a total of 40 patients. The mean age was 62.1± 12.1 years, and there was male dominant (82.5%). The index of contractility (ICON) and stroke volume index worsened after PCI but improved on the next day after the procedural day. In addition, systemic vascular resistance index decreased and the improvement of ICON on the next day had remarkable contribution on the overall contractility rather than transient diminution after intervention. Hierarchical Clustering indicated that PCI had benefits for young patients, heart failure population, and patients with moderate to severe Synergy between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery score. In addition, NT-proBNP values were analyzed, which reported a decreasing trend of level after intervention. Conclusions This study supported that PCI improved coronary flow and myocardial contractility over time after conquering the microvascular impedance. Moreover, microcirculation of coronary flow had impact on macrocirculation improvement, and it was feasible to measure the change by using electrical cardiometry.Figure 1Figure 2

Retinal venular vessel diameters are smaller during ten days of bed rest

Older individuals experience cardiovascular dysfunction during extended bedridden hospital or care home stays. Bed rest is also used as a model to simulate accelerated vascular deconditioning occurring during spaceflight. This study investigates changes in retinal microcirculation during a ten-day bed rest protocol. Ten healthy young males (22.9 ± 4.7 years; body mass index: 23.6 ± 2.5 kg·m–2) participated in a strictly controlled repeated-measures bed rest study lasting ten days. High-resolution images were obtained using a hand-held fundus camera at baseline, daily during the 10 days of bed rest, and 1 day after re-ambulation. Retinal vessel analysis was performed using a semi-automated software system to obtain metrics for retinal arteriolar and venular diameters, central retinal artery equivalent and central retinal vein equivalent, respectively. Data analysis employed a mixed linear model. At the end of the bed rest period, a significant decrease in retinal venular diameter was observed, indicated by a significantly lower central retinal vein equivalent (from 226.1 µm, CI 8.90, to 211.4 µm, CI 8.28, p = .026), while no significant changes in central retinal artery equivalent were noted. Prolonged bed rest confinement resulted in a significant (up to 6.5%) reduction in retinal venular diameter. These findings suggest that the changes in retinal venular diameter during bedrest may be attributed to plasma volume losses and reflect overall (cardio)-vascular deconditioning.

Does SarsCoV-2 infection really cause damage to retinal microcirculation in mild cases of COVID-19?

Aim To evaluate changes of retinal microcirculation in mild cases of recovered COVID-19 patients at least three months after the infection by optical coherence tomography angiography (OCTA) non-invasive method. Methods In this prospective cross-sectional study, 50 right eyes of 50 recovered COVID-19 patients were compared with 50 right eyes of age and gender-matched healthy controls. After the complete ophthalmological examination, all participants underwent OCTA measurements (RTVue XR Avanti, Optovue, Fremont, CA, USA). Results The time between the initial onset of symptoms, and ophthalmologic examination was 479.20 ±197.10 (126-754) days. Findings of ophthalmic examination of all eyes of the recovered COVID-19 patients were within normal range. Significantly reduced superficial (p=0.046) and deep (p=0.044) macular vessel density (VD) in foveal region in the eyes of the recovered COVID-19 patients was found compared with healthy controls. Significantly enlarged foveal avascular zone (FAZ) area and perimeter in the eyes of the recovered COVID-19 patients (p<0.001) were found too. Conclusion Recovered COVID-19 patients have impaired retinal microcirculation, which can be a cause of the development of retinal vascular diseases.

Treatment‐induced neuropathy of diabetes: an update

Abstract Background and aims: Treatment‐induced neuropathy of diabetes is an acute small‐fibre neuropathy associated with rapid glycaemia improvement.Methods: This study is a narrative review carried out based on a bibliographic review, using articles indexed in PubMed/Medline and Scielo.Results: This entity is more frequent in adult patients with poor previous glycaemic control. Its precise pathophysiology is unknown, but it is likely related to unrestored microcirculation changes that occurred during the hyperglycaemic period. It presents with intense, sudden neuropathic pain and autonomic dysfunction after a rapid glycaemic correction and a poorer analgesic response than in diabetic neuropathy.Conclusions: Since rapid glycaemia correction is the cause of this problem, clinical practice guidelines that can help physicians to prevent, diagnose and manage this entity should be developed. Copyright © 2023 John Wiley &amp; Sons.

Pathophysiology of coronary microvascular dysfunction

The term “coronary microvascular dysfunction” (CMD) encompasses several pathogenetic mechanisms resulting in functional and/or structural changes in the coronary microcirculation. CMD often determines angina and myocardial ischemia in a broad spectrum of cardiovascular diseases, including patients with ischemia with non-obstructive coronary arteries or ischemia with obstructive coronary artery disease, infarction with non-obstructive coronary arteries, cardiomyopathies, the Takotsubo syndrome and heart failure, especially heart failure with preserved ejection fraction.In this article, we provide updated evidence regarding the pathophysiological mechanisms underlying CMD across the different cardiovascular diseases, aiming to pave the way for further research and the development of novel strategies for a precision medicine approach.

Dynamics of retinal perfusion parameters in patients with post-COVID syndrome

BACKGROUND: A major current health issue is the rehabilitation of patients who previously had a coronavirus infection (COVID-19), as well as the treatment of patients with post-COVID syndrome. For a long time after COVID-19, patients may have complaints, including vision-related ones. One of the theories is that this may be due to long-term persistent microcirculatory retinal changes.&#x0D; AIM: To assess the long-term dynamics of retinal microcirculation changes in patients with post-COVID syndrome and to evaluate the relationship of these parameters with visual functions.&#x0D; MATERIALS AND METHODS: The main group consisting of 41 patients (82 eyes) was divided into groups depending on the severity of COVID-19: mild, moderate and severe. The control group included 13 people (26 eyes) who did not have COVID-19 to the time of the examination. All patients underwent an ophthalmological examination, including low-contrast visual acuity testing and optical coherence tomography-angiography. Vessel density (VD) was examined within the superficial capillary plexus (SCP), deep capillary plexus (DCP), and radial peripapillary capillaries (RPC). The following structural indicators were also measured: the retinal thickness, the retinal nerve fiber layer thickness and the ganglion cell complex. All patients were examined twice: 6 weeks after COVID-19 and in 27 weeks (6 months after the first visit).&#x0D; RESULTS: Patients who went through moderately severe and severe COVID-19 showed a significant decrease in low-contrast visual acuity in comparison to the control group at Visit 1 (p .001 in both cases), which totally recovered to the Visit 2. In the same group of patients, there was a significant decrease in VD SCP (p .001) and VD DCP (p .001) in comparison to the control group, and these parameters significantly decreased at visit 2 (p .001 in both cases). In the group of patients with moderate COVID-19, there was also a decrease in VD SCP and VD DCP in comparison to the control group (p .001 in both cases), while the indicators remained stable during 6 months of follow-up (p = .082). There were no significant changes in VD RPC and main morphometric parameters during 6 months of follow-up.&#x0D; CONCLUSIONS: In patients with COVID-19 from moderate severity to severe, there is a significant decrease in contrast sensitivity, which is temporary and fully recovers after 6 months. In patients with severe COVID-19, there was a negative dynamic of retinal perfusion during 6 months, both in deep and superficial capillary plexuses. Patients with post-COVID syndrome, or those who have had COVID-19 and present with visual complaints, need a deep ophthalmological examination including optical coherence tomography-angiography, with a possible involvement of related specialists.

Quantitative assessment of myocardial blood flow by dynamic single photon emission computed tomography: relationship with ECG changes and biochemical markers of damage in patients with acute myocardial infarction

Aim: To study the relationship of microcirculatory changes in coronary bed and electrocardiographic and laboratory signs of damage to myocardium in patients with acute myocardial infarction (AMI).Methods. The observational study included patients with newly emerged AMI. Depending on the ECG changes, the patients were divided into two groups: 1) with ST segment elevation (n = 75) (STEMI) and 2) without ST segment elevation (n = 44) (NSTEMI). All patients underwent electrocardiography, analysis of biochemical markers of myocardial damage, dynamic single photon emission computed tomography (SPECT) and myocardial perfusion imaging.Results. The study included 119 patients (age 62.5 ± 10.4 years, 63% men). STEMI patients had heavier perfusion defects at rest, 5.00 (3.00;9.00) and 0.00 (0.00;1.00), and after pharmacological stress test, 7.00 (5.00;13.00) and 2.50 (0.00;5.00), also they had more reduced stress myocardial blood flow (MBF), 1.09 (0.83;1.59) and 1.67 (1.36;2.46) ml/min/g, flow difference (FD), 0.36 (0.01;0.72) and 1.14 (0.63;1.72) ml/min/g, and myocardial flow reserve (MFR), 1.78 (1.11;2.19) and 2.57 (2.13;3.31), according to compared to NSTEMI patients. Correlation analysis revealed significant relationships between stress MBF and CPK after 24 hours and 4 days: r = –0.34 and r = = –0.31, troponin I upon admission and after 24 hours – r = –0.4 and r = –0.3; MFR and FD and troponin I upon admission – r = –0.41 and r = –0.41.Conclusion. Quantitative parameters of myocardial perfusion determined by early dynamic myocardial SPECT are associated with electrocardiographic changes and biochemical markers of myocardial damage and allow an adequate assessment of the severity of the disease in patients with AMI.

Вплив блокади тирозинових протеїнкіназ на експресію васкулоендотеліального фактора росту та розвиток діабетичної ретинопатії

One of the main factors in the development of diabetic retinopathy (DR) is vasculoendothelial growth factor (VEGF), which is the end product of the activation of several intracellular signaling pathways, including those triggered by the activation of receptor tyrosine protein kinases. There is a need to justify new approaches to influence the expression of VEGF, not only in the late but also in the early stages of DR. Diabetes was modeled in 45 three-month-old male Wistar rats by a single injection of streptozotocin (50 mg/kg; Sigma- Aldrich, China). Hyperglycemia led to the development of early (on the 7–28th day) morphological manifestations of DR, indicating pronounced degenerative changes in nerve cells, microcirculation, and metabolism disorders. The use of insulin resulted in fewer diabetic changes in the retina, while the combined use of insulin and the tyrosine protein kinase blocker imatinib prevented the morphological manifestations of DR. According to the results of an immunohistochemical study, overexpression of VEGF was observed in the retinal tissue, which was inhibited by the introduction of insulin and, to a greater extent, by the combination of insulin with imatinib. According to immunoblotting results, the levels of VEGF and hypoxia-inducible factor (HIF-1) in the retinal tissue increased several-fold, which was significantly inhibited by insulin and prevented by insulin in combination with imatinib. Thus, this suggests that blockade of tyrosine protein kinases may be a highly effective way of preventing or correcting the damage caused by DR.

Contrast Echocardiography for Assessing Myocardial Perfusion.

Improvements in ultrasound methods for detecting microbubble ultrasound enhancing agents have led to an increase in the use of perfusion imaging with myocardial contrast echocardiography (MCE). This technique is now beginning to play an important role in specific clinical scenarios, which is the focus of this review. MCE was originally conceived as a technique for detecting resting perfusion abnormalities related to ischemia at rest or during stress from coronary artery disease. More recently, MCE has increasingly been used in circumstances where the technique's ability to provide rapid, quantitative, or bedside assessment of perfusion is advantageous. Quantitative MCE is also increasingly being used as a research technique for evaluating pathobiology and therapy that involve changes in the myocardial microcirculation. While MCE was developed and validated decades ago, it is only now beginning to be used by an increasing number of clinicians due to improvements in imaging technology and recognition of specific situations where the technique is impactful.

Involvement of the systemic microcirculation in pediatric uveitis

BackgroundPediatric uveitis is a severe inflammatory ocular condition that can lead to sight-threatening complications and can negatively impact quality of life. The retinal microcirculation is often affected in intermediate uveitis and panuveitis. Here, we examined the extraocular (i.e., systemic) microcirculation in pediatric uveitis cases and healthy controls using nailfold capillaroscopy (NFC).MethodsWe performed NFC in 119 children with noninfectious uveitis and 25 healthy pediatric controls, and assessed the following parameters: capillary density (number of capillaries/mm), dilated capillaries (apex > 20 µm), avascular area, the presence of microhemorrhages, and capillary morphology. Differences in NFC parameters between cases and controls were calculated using regression analysis after adjusting for age and sex.ResultsThe mean (± SD) age of the patient group was 13.7 (± 3) years, with 56% females; 46%, 18%, and 36% of cases presented as anterior uveitis, intermediate uveitis, and panuveitis, respectively, with an overall mean disease duration of 4.7 (± 4.0) years. Compared to the control group, the pediatric uveitis cases had a significantly higher number of dilated capillaries/mm and a higher prevalence of ramified capillaries. Moreover, compared to the control group the intermediate uveitis cases had a significantly higher number of dilated capillaries, whereas the anterior uveitis cases had a lower capillary density and a higher prevalence of ramified capillaries.ConclusionsChildren with uveitis without systemic disease can present with changes in systemic microcirculation. These changes vary amongst the subtypes of uveitis.

Comprehensive Assessment of Eyes in Kidney Transplant Recipients after Recovering from COVID-19.

Patients after organ transplantation with COVID-19 have a higher risk of morbidity and mortality than patients in the general population. There are single studies that assess the eyes of COVID-19 patients, but there are no such studies on organ transplant recipients. The purpose of this study was to comprehensively examine the eyes of kidney transplant recipients (KTR) after recovery from mild to moderate SARS-CoV-2 infection. A total of 40 KTR after COVID-19 and 20 KTR without clinical and immunological symptoms of SARS-CoV-2 infection as a control group was qualified for the cross-sectional study. A total of 76 eyes from 38 KTR on an average of 7 weeks after COVID-19 and 36 eyes from 18 KTR from the control group were studied. The participants underwent an ophthalmological examination, and the retinal and choroid vessels and nerves were assessed by optical coherence tomography angiography. We found a lower vessel density (VD) in the deep capillary plexus in the central part of the retina (VD deep central) of the study group. Women had significantly lower VD deep central in the study group (15.51 vs. 18.91, p < 0.001). Multivariate linear regression analysis confirmed an independent, negative impact of COVID-19 (p < 0.001) and female gender (p = 0.001) on VD deep central. The results of our study confirmed that changes in microcirculation induced by SARS-CoV-2 infection may affect the retinal vessels in KTR. Mild to moderate COVID-19 in KTR resulted in a significant reduction in VD deep central of the retina, with these changes being more common in females.

Evaluation of Myocardial Microcirculation in Rats under a High-Altitude Hypoxic Environment by Computed Tomography Myocardial Perfusion Imaging.

This study aims to examine the changes in myocardial microcirculation in rats in a high-altitude hypoxic environment via computed tomography (CT) myocardial perfusion imaging technology. Rats in two groups were raised in different environments from 4 weeks of age for a period of 24 weeks. At 28 weeks of age, both groups underwent CT myocardial perfusion scanning, and the following myocardial perfusion parameters were measured: time to peak (TTP), mean transit time (MTT), blood flow (BF), and blood volume (BV). Following the scan, the rats were sacrificed, the cardiac index and right ventricular hypertrophy index were obtained, and hematoxylin-eosin (HE) staining was utilized to observe the pathological changes in the myocardium. In the group of rats that are subject to a high-altitude hypoxic environment for 24 weeks (the high-altitude group), the TTP and MTT values were increased (P < 0.05), the BF and BV values were lower (P < 0.05), the right heart mass was higher (P < 0.05) than that in the low-altitude group. As shown by the pathological results of HE staining, the gap between cardiomyocytes in the high-altitude group was widened, the arrangement of cardiomyocytes was irregular, and the cells were filled with a few fat vacuoles. The myocardial microcirculation is altered in a high-altitude hypoxic environment. In particular, the myocardium is in a state of inadequate perfusion, the BF in the myocardium slows down, and the right heart displays compensatory hypertrophy.

Abdominal perfusion in canine patients with pyometra and sepsis evaluated by Doppler and contrast-enhanced ultrasound

BackgroundSepsis is a condition characterized by organic dysfunction, leading to hemodynamic instability and high morbidity and mortality rates in humans and animals. Early identification of perfusion changes and appropriate management of sepsis are crucial for improving patient prognosis. Currently, the Systemic Inflammatory Response Syndrome (SIRS) and Sequential Organ Failure Assessment (SOFA) scores are widely studied for sepsis identification and evaluation of organ dysfunction. However, these scores do not assess gastrointestinal involvement, which is common in this condition. Contrast-enhanced ultrasound (CEUS) and Doppler have been considered promising diagnostic techniques for detecting changes in vascularization and microcirculation in a non-invasive and safe manner, particularly in the gastrointestinal system. This study aimed to evaluate duodenal perfusion using CEUS, as well as abdominal aortic and cranial mesenteric artery blood flow using Doppler ultrasound, and systolic arterial pressure (SAP) in 17 bitches with pyometra and in 10 healthy animals.ResultsThe variables were compared between the pyometra and control groups, as well between patients with and without sepsis determined by the SOFA or SIRS scores. Pyometra was found to cause a reduction in abdominal aortic blood flow volume, aortic peak systolic velocity, and resistivity index as evaluated by Doppler ultrasound. Patients with sepsis according to the SOFA criteria only presented lower SAP. In contrast, sepsis animals identified by the SIRS score exhibited lower SAP, aortic peak systolic velocity, aortic blood flow volume, and aortic resistivity index and additionally, higher peak intensity of contrast in the duodenal wall.ConclusionsPyometra causes a reduction in abdominal aortic blood flow, which is more pronounced in animals with sepsis identified by the SIRS criteria. These animals also exhibited a decrease in systolic blood pressure and an increase in duodenal perfusion, as evident by CEUS. However, these changes were not observed in patients with sepsis identified by the SOFA criteria. The alterations in intestinal perfusion observed in animals with sepsis indicate the presence of inflammation or dysfunction. In this regard, CEUS proves to be a valuable technique for detecting subtle changes in tissue hemodynamics that may not be apparent in conventional exams.

Rational and design of the REMOTE trial: An exploratory, pilot study to analyze REtinal MicrOcirculaTion in wEightlessness.

"Spaceflight associated neuro-ocular syndrome" (SANS) represents a challenging health condition in modern space medicine. Forty-eight percent of astronauts are diagnosed with SANS after long-term space missions. The pathophysiological mechanism seems to be multifactorial, and yet remains unknown. In this proof-of-concept study we plan to investigate retinal microcirculatory changes in weightlessness and aim to identify their role in the development of SANS. Healthy individuals will take part in a parabolic flight campaign, which recreates fractioned total weightlessness periods. The airplane is specifically equipped, and designed for the execution of parabolic flight maneuvers and scientific research in microgravity. Retinal microcirculation will be assessed with a modified fundus camera, which allows dynamic vessel analysis. We will additionally measure intra-ocular pressure and hemodynamic changes during each phase of the flight. Blood samples will be analyzed at baseline, one hour and 24 hours after exposure to weightlessness. This pilot study aims to investigate the feasibility of retinal microcirculation assessment during varying gravity. Results of this study may generate insights whether venous stasis in the eye, surrogated by the dilatation of retinal vessels and increase in intraocular pressure as signs of venous insufficiency, may potentially contribute to the development of SANS.

Sex Variations in Retinal Microcirculation Response to Lower Body Negative Pressure.

Lower body negative pressure (LBNP) is routinely used to induce central hypovolemia. LBNP leads to a shift in blood to the lower extremities. While the effects of LBNP on physiological responses and large arteries have been widely reported, there is almost no literature regarding how these cephalad fluid shifts affect the microvasculature. The present study evaluated the changes in retinal microcirculation parameters induced by LBNP in both males and females. Forty-four participants were recruited for the present study. The retinal measurements were performed at six time points during the LBNP protocol. To prevent the development of cardiovascular collapse (syncope) in the healthy participants, graded LBNP until a maximum of -40 mmHg was applied. A non-mydriatic, hand-held Optomed Aurora retinal camera was used to capture the retinal images. MONA Reva software (version 2.1.1) was used to analyze the central retinal arterial and venous diameter changes during the LBNP application. Repeated measures ANOVAs, including sex as the between-subjects factor and the grade of the LBNP as the within-subjects factor, were performed. No significant changes in retinal microcirculation were observed between the evaluated time points or across the sexes. Graded LBNP application did not lead to changes in the retinal microvasculature across the sexes. The present study is the first in the given area that attempted to capture the changes in retinal microcirculation caused by central hypovolemia during LBNP. However, further research is needed with higher LBNP levels, including those that can induce pre-fainting (presyncope), to fully understand how retinal microcirculation adapts during complete cardiovascular collapse (e.g., during hypovolemic shock) and/or during severe hemorrhage.

Characterization of ink-based phantoms with deep networks and photoacoustic method

&lt;p class="abstract"&gt;This study aims to explore the feasibility of using an in-house developed photoacoustic (PA) system for predicting blood phantom concentrations using a pretrained Alexnet and a Long Short-Term Memory (LSTM) network. In two separate experiments, we investigate the performance of our strategy using a point laser source and a color-tunable Light-Emitting Diode (LED) as the illumination source. A single-point transducer is employed to measure signal change by adding ten different black ink concentrations into a tube. These PA signals are used for training and testing the employed deep networks. We found that the LED system with light wavelength of 450 nm gives the best characterization performance. The classification accuracy of the Alexnet and LSTM models tested on this dataset shows an average value of 94% and 96%, respectively, making this a preferred light wavelength for future operation. Our system may be used for the noninvasive assessment of microcirculatory changes in humans.&lt;/p&gt;

Peculiarities of paravulvar microcirculation in skin and muscle in blast wound in variants of early local injection of reparative active agent

Introduction. A promising method of correcting microcirculatory disorders in the area of soft tissue injury is the use of agents with antihypoxant action, which include deproteinized calf-blood hemoderivate.The aim of the work was to reveal the peculiarities of subcutaneous and intramuscular local injection of deproteinized calfblood hemoderivate on the changes of microcirculation in the skin and muscles in the experimental blast wound area.Materials and methods. The experiments were performed on 90 male Wistar rats weighing (320±20) g in compliance with international rules of work with laboratory animals. Modeling of an explosive wound of the soft tissues of the femur with mild degree of blood loss was carried out according to the original author’s method (Patent RU No. 2741238 dated 22.01.2021). After primary surgical treatment was performed paravulnarly, deproteinized calf-blood hemoderivate was injected intramuscularly, intramuscularly and subcutaneously (Actovegin drug) once in six points with an insulin syringe. Microcirculation in the skin and muscles of the injured area was assessed by laser Doppler flowmetry using the device LAKK-M (Russia). To determine the normal values of microcirculation, data obtained from healthy animals were used.Results. Local intramuscular injection into the paravular area resulted in an increase of the constant perfusion component (M) by 24.1−35.9 % (p &lt; 0.05) and by 18.0−56.4 % (p &lt; 0.05) in the skin and muscles during all periods of observation, an increase of the variable perfusion component (σ) in the skin by 31.4−38.0 % (p &lt; 0.05) during 28 days and in muscles by 8.8−58.7 % (p &lt; 0.05) during the first 14 days only, increase of Kv ratio in skin by 12.4 % (p = 0.01) early after injury (7 days) and decrease in muscles by 18.3−20.8% (p &lt; 0.05) at 14−28 days. Local combined administration (intramuscularly and subcutaneously) of the drug around the wound promoted the increase of the constant perfusion component (M) in the skin by 23.8 % (p = 0.005) and 6.9 % (p = 0.01) at the 7th and 28th days of observation, increase of σ index in skin by 14.2−45.1 % (p &lt; 0.007) on the 7−14 days and its decrease in muscles by 15.7 % (p = 0.009) by the end of the 7th day of observation in comparison with animals after only intramuscular injection only. Also, the coefficient of variation (Kv) with the combined route of injection was increased in the skin by 8.8−23.8 % (p &lt; 0.009) in the first 14 days and decreased in the muscles by 15.7 % (p = 0.008) in the early period after injury (7 days) relative to its values in animals with intramuscular injection.Discussion. The results of the study allow noting the stimulating effect of deproteinized calf-blood hemoderivate on neovasculogenesis in the damaged tissues, which can be judged by the increase in the constant perfusion component (M). In addition, we can conclude that the direct endothelium-protective effect of the drug consists in the modulation of microcirculatory flow, which confirms the significant increase in the variable perfusion component (σ) throughout the experiment.Conclusion. Local paravular administration of deproteinized calf-blood hemoderivate in experimental blast wound promotes microcirculation increase in the soft tissues of the injury area. Combined (intramuscular and subcutaneous) local paravular injection of the drug allows more effective stimulation of microcirculation in the skin and muscles of the injury area.