Perfusion Levels Research Articles

Peculiarities of the body component composition and microcirculation of qualified divers

One of the important aspects of improving the effectiveness of training qualified divers is understanding the peculiarities of body component composition and the state of microcirculation. The aim of this study was to investigate the component body composition and microcirculation peculiarities of qualified divers diving from different types of gymnastic equipment. The study sample included 30 qualified divers, consisting of 17 girls and 13 boys aged 13 to 18 years. Body composition was assessed using bioimpedance analysis, and the functional state of the microcirculatory system was evaluated through laser Doppler flowmetry. The results indicated that divers who utilized the 10-meter tower exhibited a statistically significant decrease in adipose tissue content and an increase in fat-free mass and relative muscle mass compared to athletes in other diving disciplines. Additionally, a high level of tissue perfusion and microvascular reactivity was observed among the athletes. These findings are crucial for assessing and enhancing the training effectiveness of qualified diving athletes.

Effects of veno-arterial extracorporeal membrane oxygenation return cannula side hole structure on aortic hemodynamic features under different perfusion levels.

The interaction between primary left ventricular output and Veno-arterial extracorporeal membrane pulmonary oxygenation (VA ECMO) flow may impede the perfusion of aortic vessels with hyperoxic blood, leading to differential oxygenation. ECMO return cannula design significantly influences the perfusion level of blood supplied via ECMO. This study aimed to investigate the impact of various cannula designs (side hole number) on intravascular flow patterns under different blood perfusion conditions. Six return cannula models with different side hole number and three cardiac output waveforms were designed based on clinical data for comparative analysis. The position of the blood mixing zone (MZ) was influenced by the flow-volume ratio of the heart output (CO/(CO+Qec)) and cannula design. As the CO/(CO+Qec) and the number of side holes in the cannula increased, the MZ shifted from the ascending aorta to the descending aorta. Concurrently, aortic wall and scalar shear stress on the impact side of ECMO cannulation reduced progressively. Return cannula with side holes effectively mitigated discrepancies in the perfusion of the renal artery and inadequate perfusion of the lower limb vessels on the cannula side while simultaneously reducing damage to the vessel walls and blood. However, increasing the number of side holes in the return cannulas resulted in diminished perfusion of the aortic arch bifurcation vessels by hyperoxic blood supplied via ECMO. Increasing the number of return cannula side holes for VA ECMO femoral artery cannulation improves hypoxic perfusion in the lower limb and reduces vascular endothelial injury, but may also lead to inadequate hypoxic perfusion in the upper body.

Influence of Age and Sex on Stability Indicators of the Right-Left Hemodynamic Balance of Skin Microcirculation in Symmetrical Areas of the Human Head.

Indicators (markers) of microcirculation stability (MCR) of the skin in symmetric areas of the head were studied in young (18-19-years-old) and elderly (60-80-years-old) male and female subjects. We performed synchronous MCR measurements of symmetrical areas of the head using laser Doppler flowmetry in 40 healthy volunteers (10 men and 10 women in each age group). Numerical values of stability markers (T1, T2, and ζ) and indicators of the right-left hemodynamic balance of the MCR (regression coefficients a1, a2, b1, b2) were obtained using the previously developed computational and experimental methods. The coefficients a2 and b2 that determine the contribution of the right MCR bed to the right-left hemodynamic balance were higher in elderly men than in young men, while in young and elderly women, no significant differences in the values of these coefficients were revealed. In young men, coefficients a2 and b2 were lower than in young women, while in elderly subjects, the sex differences in these coefficients were leveled. Young men have lower stability markers than women, while in elderly subjects, these stability markers were similar in men and women. No significant age and sex differences in the level of perfusion of the symmetrical temporal regions were found. The results attest to low stability of MCR in young men in comparison with young women and similar stability in old age, which, apparently, can be explained by the influence of sex hormones on the regulation of human cardiovascular functions.

Arterial hypoperfusion as a negative predictive marker for primary hepatic malignancies treated with Y-90 glass microsphere transarterial radioembolization.

Radioembolization with yttrium-90 (Y-90) is utilized to treat primary liver malignancies. The efficacy of this intra-arterial therapy in arterially hypoperfused tumors is not known. We reviewed data of patients with primary liver tumors treated with Y-90 prescription doses of at least 150 Gy. Baseline patient characteristics, treatment history, imaging-based tumor response assessments, and clinical outcome metrics were recorded. Tumors were classified as arterially hyperperfused versus hypoperfused on post-TARE Y-90 SPECT/CTs or pre-TARE hepatic perfusion SPECT/CTs. Perfusion status was correlated with tumor response assessments and clinical outcomes. Cox proportional hazards models were utilized to compare survival and progression-free survival. Inverse probability weighting was utilized to account for clinical factors and adjusted multivariable proportional hazards analyses to examine the relationship of quantitative perfusion and cancer outcomes. Of 400 Y-90 treatments, 88 patients received a prescribed dose of at least 150 Gy and had pre- or post-treatment SPECT/CT images. 11 and 77 patients had arterially hypoperfused and hyperperfused lesions, respectively. On dedicated liver MRI or CT at 3 months after Y-90, the complete response rates were 5.6% and 16.5% in the hypoperfused and hyperperfused cohort, respectively (P = 0.60). When controlling for various clinical features, including tumor histology, patients with arterially hypoperfused tumors had significantly shorter progression-free survival (HR 1.87, 95% CI - 1.03 - 3.37, P = 0.039) and greater elsewhere liver (HR 3.36, 95% CI = 1.23 - 9.20, P = 0.019) and distant failure (HR 7.64 (2.71 - 21.54, P < 0.001). In inverse probability weighted analysis, patients with arterially hypoperfused tumors had worse overall survival (P = 0.032). In the quantitative analysis, lower levels of lesion perfusion were also associated with worse clinical outcomes, again controlling for tumor histology. Compared to arterially hyperperfused tumors, hypoperfused primary liver tumors treated with Y-90 may have worse clinical outcomes.

Altered brain perfusion and oxygen levels relate to sleepiness and attention in post-COVID syndrome.

Persisting neurological symptoms after COVID-19 affect up to 10% of patients and can manifest in fatigue and cognitive complaints. Based on recent evidence, we evaluated whether cerebral hemodynamic changes contribute to post-COVID syndrome (PCS). Using resting-state functional magnetic resonance imaging, we investigated brain perfusion and oxygen level estimates in 47 patients (44.4 ± 11.6 years; F:M = 38:9) and 47 individually matched healthy control participants. Group differences were calculated using two-sample t-tests. Multivariable linear regression was used for associations of each regional perfusion and oxygen level measure with cognition and sleepiness measures. Exploratory hazard ratios were calculated for each brain metric with clinical measures. Patients presented with high levels of fatigue (79%) and daytime sleepiness (45%). We found widespread decreased brain oxygen levels, most evident in the white matter (false discovery rate adjusted-p-value (p-FDR) = 0.038) and cortical grey matter (p-FDR = 0.015). Brain perfusion did not differ between patients and healthy participants. However, delayed patient caudate nucleus perfusion was associated with better executive function (p-FDR = 0.008). Delayed perfusion in the cortical grey matter and hippocampus were associated with a reduced risk of daytime sleepiness (hazard ratio (HR) = 0.07, p = 0.037 and HR = 0.06, p = 0.034). Decreased putamen oxygen levels were associated with a reduced risk of poor cognitive outcome (HR = 0.22, p = 0.019). Meanwhile, lower thalamic oxygen levels were associated with a higher risk of cognitive fatigue (HR = 6.29, p = 0.017). Our findings of lower regional brain blood oxygen levels suggest increased cerebral metabolism in PCS, which potentially holds a compensatory function. These hemodynamic changes were related to symptom severity, possibly representing metabolic adaptations.

Dye-less quantification of tissue perfusion by laser speckle contrast imaging is equivalent to quantified indocyanine green in a porcine model.

Subjective surgeon interpretation of near-infrared perfusion video is limited by low inter-observer agreement and poor correlation to clinical outcomes. In contrast, quantification of indocyanine green fluorescence video (Q-ICG) correlates with histologic level of perfusion as well as clinical outcomes. Measuring dye volume over time, however, has limitations, such as it is not on-demand, has poor spatial resolution, and is not easily repeatable. Laser speckle contrast imaging quantification (Q-LSCI) is a real-time, dye-free alternative, but further validation is needed. We hypothesize that Q-LSCI will distinguish ischemic tissue and correlate over a range of perfusion levels equivalent to Q-ICG. Nine sections of intestine in three swine were devascularized. Pairs of indocyanine green fluorescence imaging and laser speckle contrast imaging video were quantified within perfused, watershed, and ischemic regions. Q-ICG used normalized peak inflow slope. Q-LSCI methods were laser speckle perfusion units (LSPU), the base unit of laser speckle imaging, relative perfusion units (RPU), a previously described methodology which utilizes an internal control, and zero-lag normalized cross-correlation (X-Corr), to investigate if the signal deviations convey accurate perfusion information. We determine the ability to distinguish ischemic regions and correlation to Q-ICG over a perfusion gradient. All modalities distinguished ischemic from perfused regions of interest; Q-ICG values of 0.028 and 0.155 (p < 0.001); RPU values of 0.15 and 0.68 (p < 0.001); and X-corr values of 0.73 and 0.24 (p < 0.001). Over a range of perfusion levels, RPU had the best correlation with Q-ICG (r = 0.79, p < 0.001) compared with LSPU (r = 0.74, p < 0.001) and X-Corr (r = 0.46, p < 0.001). These results demonstrate that Q-LSCI discriminates ischemic from perfused tissue and represents similar perfusion information over a broad range of perfusion levels comparable to clinically validated Q-ICG. This suggests that Q-LSCI might offer clinically predictive real-time dye-free quantification of tissue perfusion. Further work should include validation in histologic studies and human clinical trials.

Exploring laser-induced acute and chronic retinal vein occlusion mouse models: Development, temporal in vivo imaging, and application perspectives.

Photodynamic venous occlusion is a commonly accepted method for establishing mouse models of retinal vein occlusion (RVO). However, existing model parameters do not distinguish between acute and chronic RVO subtypes. Large variations in laser energy seem to correlate with fluctuating retinopathy severity and high rates of venous recanalization during the acute phase, along with the variable levels of retinal perfusion during the chronic phase. After optimizing the modeling procedure and defining success and exclusion criteria, laser energy groups of 80mW, 100mW, and 120mW were established. Multimodal imaging confirmed that higher energy levels increased the incidence of retinal cystoid edema and intraretinal hemorrhage, exacerbated the severity of exudative retinal detachment, and reduced the venous recanalization rate. For the acute model, 100mW was considered an appropriate parameter for balancing moderate retinopathy and venous recanalization. Continuous imaging follow-up revealed that day 1 after RVO was the optimal observation point for peaking of retinal thickness and intensive occurrence of retinal cystic edema and intraretinal hemorrhage. After excluding the influence of venous recanalization on retinal thickness, acute retinal edema demonstrated a positive response to standard anti-vascular endothelial growth factor therapy, validating the clinical relevance of the acute RVO model for further study in pathogenic mechanisms and therapeutic efficacy. For the chronic model, the 120mW parameter with the lowest venous recanalization rate was applied, accompanied by an increase in both photocoagulation shots and range to ensure sustained vein occlusion. Imaging follow-up clarified non-ischemic retinopathy characterized by tortuosity and dilation of the distal end, branches, and adjacent veins of the occluded vein. These morphological changes are quantifiable and could be combined with electrophysiological functional assessment for treatment effectiveness evaluation. Moreover, the stable state of venous occlusion may facilitate investigations into response and compensation mechanisms under conditions of chronic retinal hypoperfusion.

Ferroptosis Inhibition with Deferoxamine Alleviates Radiation-Induced Fibrosis.

Background Radiation-induced fibrosis (RIF) is a debilitating sequelae of radiation therapy that has been shown to improve with topical treatment with the iron chelator deferoxamine (DFO). We investigated whether DFO exerts this effect through attenuation of ferroptosis, a recently described iron-dependent pathway of cell death. Methods Adult C57BL/6J mice were treated with topical DFO or ferrostastin-1 (Fer-1) and irradiated with 30 Grays of ionizing radiation to the dorsal skin to promote development of chronic RIF. Immunofluorescent staining with 4-hydroxynonenal (4-HNE) antibody was carried out directly following irradiation to assess ferroptosis activity. Perfusion testing with laser Doppler was performed throughout the healing interval. Eight weeks following radiation, dorsal skin was harvested and analyzed histologically and biomechanically. Results Immunohistochemical staining demonstrated lower presence of 4-HNE in non-irradiated skin, DFO-treated skin, and Fer-1-treated skin compared to irradiated, untreated skin. DFO resulted in histological measurements (dermal thickness and collagen content) that resembled normal skin, while Fer-1 treatment yielded less significant improvements. These results were mirrored by analysis of extracellular matrix ultrastructure and biomechanical testing, which recapitulated the ability of topical DFO treatment to alleviate RIF across these parameters while Fer-1 resulted in less notable improvement. Finally, perfusion levels in DFO treated irradiated skin were similar to measurements in normal skin, while Fer-1 treatment did not impact this feature. Conclusions Ferroptosis contributes to the development of RIF and attenuation of this process leads to reduced skin injury. DFO further improves RIF through additional enhancement of perfusion not seen with Fer-1.

Advancements in non-invasive hyperspectral imaging: Mapping blood oxygen levels and vascular health for clinical and research applications

Oxygen content is crucial for the functioning of human body organs, as it plays a vital role in cellular respiration, which generates energy necessary for life-sustaining functions. The absence of adequate oxygen leads to cellular dysfunction and eventual organismal death due to energy deprivation.In this study, we designed a rapid, non-invasive, and non-contact custom hyperspectral imaging system to assess blood perfusion in arteries, capillaries, and veins across various human organs, including the arm, eye, and leg. The system recorded cube images consisting of multispectral image ranges, capturing spectral information in both the visible and infrared spectra. Segmentation of the visible spectrum (400 to 700 nm) and the infrared spectrum (700 to 1000 nm) facilitated the mapping of blood oxygen levels in the investigated samples.The estimated oxygen levels were calculated using the custom hyperspectral imaging system and associated algorithm, with validation and calibration performed against the gold standard pulse oximeter. Our results demonstrate that the custom hyperspectral imaging system accurately mapped blood perfusion and oxygen levels in organs, showing strong agreement with pulse oximeter measurements.This study underscores the utility of custom hyperspectral imaging in non-invasively assessing blood oxygenation and perfusion in human organs, offering a promising avenue for clinical diagnostics and monitoring of vascular health.

Impact of Fat Distribution and Metabolic Diseases on Cerebral Microcirculation: A Multimodal Study on Type 2 Diabetic and Obese Patients.

Background: Since metabolic diseases and atherosclerotic vascular events are firmly associated, herein we investigate changes in central microcirculation and atherosclerosis-related body fat distribution in patients with type 2 diabetes mellitus and obesity. Methods: Resting brain perfusion single-photon emission computed tomography (SPECT) imaging with Technetium-99m hexamethylpropylene amine oxime ([99mTc]Tc-HMPAO SPECT) was performed, and the breath-holding index (BHI) and carotid intima-media thickness (cIMT) were measured to characterise central microcirculation. Besides CT-based abdominal fat tissue segmentation, C-peptide level, glycaemic and anthropometric parameters were registered to search for correlations with cerebral blood flow and vasoreactivity. Results: Although no significant difference was found between the resting cerebral perfusion of the two patient cohorts, a greater blood flow increase was experienced in the obese after the breath-holding test than in the diabetics (p < 0.05). A significant positive correlation was encountered between resting and provocation-triggered brain perfusion and C-peptide levels (p < 0.005). BMI and cIMT were negatively correlated (rho = -0.27 and -0.23 for maximum and mean cIMT, respectively), while BMI and BHI showed a positive association (rho = 0.31 and rho = 0.29 for maximum and mean BHI, respectively), which could be explained by BMI-dependent changes in fat tissue distribution. cIMT demonstrated a disproportional relationship with increasing age, and higher cIMT values were observed for the men. Conclusions: Overall, C-peptide levels and circulatory parameters seem to be strong applicants to predict brain microvascular alterations and related cognitive decline in such patient populations.

Quantitative analysis of intestinal perfusion with indocyanine green (ICG) and methylene blue (MB) using a single clinically approved fluorescence imaging system: a demonstration in a porcine model

BackgroundNear-infrared fluorescence (NIRF) angiography with intraoperative administration of indocyanine green (ICG) has rapidly disseminated in clinical practice. Another clinically approved, and widely available dye, methylene blue (MB), has up to now not been used for this purpose. Recently, we demonstrated promising results for the real-time evaluation of intestinal perfusion using this dye. The primary aim of this study was to perform a quantitative analysis of bowel perfusion assessment for both ICG and MB.MethodsFour mature female Landrace pigs underwent laparotomy under general anesthesia. An ischemic bowel loop with five regions of interest (ROIs) with varying levels of perfusion was created in each animal. An intravenous (IV) injection of 0.25 mg/kg–0.50 mg/kg MB was administered after 10 min, followed by NIRF imaging in MB mode and measurement of local lactate levels in all corresponding ROIs. This procedure was repeated in ICG mode (IV dose of 0.2 mg/kg) after 60 min. The quest spectrum fluorescence camera (Quest Medical Imaging, Middenmeer, The Netherlands) was used for NIRF imaging of both MB and ICG.ResultsIntraoperative NIRF imaging of bowel perfusion assessment with MB and ICG was successful in all studied animals. Ingress (i/s) levels were calculated and correlated with local lactate levels. Both MB and ICG ingress values showed a significant negative correlation (r = − 0.7709; p = < 0.001; r = − 0.5367, p = 0.015, respectively) with local lactate levels. This correlation was stronger for MB compared to ICG, although ICG analysis showed higher absolute ingress values.ConclusionOur fluorescence quantification analysis validates the potential to use MB for bowel perfusion assessment besides the well-known and widely used ICG. Further human studies are necessary to translate our findings to clinical applications.

5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR) improves lipid utilization but not survival following prolonged hemorrhagic shock

Hemorrhagic shock induces insulin resistance and cellular ATP depletion, the initial step for cell death and organ injury. AMPK is a fuel-sensing enzyme that maintains ATP production by facilitating glucose and fatty acid uptake and oxidation. Using a previously developed rat model of AKI induced by prolonged hemorrhagic shock, we tested the hypothesis that AICAR, an AMPK activator, can enhance fuel consumption, delay onset of AKI, and increase survival following prolonged hemorrhagic shock. Additionally, we hypothesized that AICAR requires 7.5% polyethylene glycol-20k (PEG) to elicit the catabolism effect, as PEG enhances the capillary perfusion in the absence of resuscitation, and thus, in theory, facilitates AICAR delivery into ischemic tissues. Rats were randomized into 4 groups (n=8/group) based on treatment: saline (vehicle), AICAR, PEG, and AICAR+PEG. Trauma was induced in (Inactin) anesthetized rats with muscle injury and fibula fracture, followed by pressure-controlled hemorrhagic shock (MAP = 55 mmHg) for 45 minutes. Animals then received an intravenous injection of saline (vehicle), AICAR, PEG, or AICAR+PEG. MAP, blood gases, RBF, renal oxygen delivery, capillary perfusion and tissue oxygen levels in the skeletal muscle were monitored for another 2 hours. GFR and mortality were recorded at the end of the experiment. The saline group exhibited impaired tissue perfusion and GFR with 100% mortality. AICAR alone showed no effect on hemodynamics, renal function, or mortality (100%). PEG and AICAR+PEG similarly improved MAP, capillary perfusion in the skeletal muscle, renal blood flow, renal oxygen delivery, and GFR. Compared to PEG, free FA levels were further decreased in AICAR+PEG, which was concomitant with elevated lactate levels and blunted oxygen partial pressure in the skeletal muscle despite the improved capillary perfusion. The mortality was 12.5% in PEG and 50% in AICAR+PEG. Our results suggest that AICAR+PEG does enhance fuel utilization but fails to further improve the tolerance to hemorrhagic shock, possibly due to a shift of oxygen consumption from vital organs to peripheral tissue. Importantly, the catabolism effect of AICAR relies on suffcient tissue perfusion, suggesting that PEG might be potentially considered as a routine therapeutic tool to optimize drug delivery during hemorrhagic shock. DoD disclaimer: The views expressed in this article are those of the author(s) and do not reflect the offcial policy or position of the U.S. Army Medical Department, Department of the Army, DoD, or the U.S. Government. Funding: This study was funded by US Army Medical Research and Development Command. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

A Parameter Identification Approach towards Hemodynamics based on Capnography

Research question Pulse detection decisions during cardiopulmonary resuscitation (CPR) are commonly augmented by end-tidal CO2-concentration (etCO2) levels and trend as etCO2 is a surrogate measure of systemic blood flow during (CPR)1. However, ventilatory and circulatory parameters influence the interpretability of etCO2 heavily. Recently developed methods of continuous cardiac output measurement based on capnography are not applicable during CPR due to the required controlled ventilation settings2. In this study, a parameter identification for a model of CO2 transport during resuscitation is used to estimate cardiac output based on capnography and tidal flow. Methodology After development of a compartmental ordinary differential equation (ODE) model to represent CO2 transport during CPR, parameters such as airway dead space and the level of systemic perfusion are estimated by a multishooting parameter identification approach3. To evaluate the method, tests are conducted on experimental data from a porcine model (approved by an ethics committee vote of the Austrian Federal Ministry of Education, Science and Research (GZ: 2021-0.895.386)). The estimated level of systemic perfusion is compared visually to invasively measured mean arterial pressure due to a lack of continuous cardiac output measurements as a ground truth. Results For exemplary data from a female pig (weight 50.4 kg), airway resistance was estimated to 20.8 hPa s /L, compliance: 25.2 mL/hPa, and dead space: 109 mL. Changes in cardiac output can be identified qualitatively as shown in Fig. 1. Conclusion A validated, simple ODE model for CO2 extraction during CPR could contribute quantifying the impact of ventilatory parameters on etCO2 and elucidate CO2 production, storage and transport during cardiac arrest. Assumptions on CO2 production during cardiac arrest and redistribution in the body, and the lacking cardiac output measurements complicate the analysis. Conflicts of Interest All authors have no conflict of interest to declare.

Functional state of dermal circulation in patients with lichen planus

Lichen planus belongs to the group of the most common dermatoses. The etiology and mechanisms of development of lichen planus are not fully understood. This dermatosis is characterized by a variety of clinical forms, as well as a chronically relapsing course, and a fairly frequent resistance to traditional therapies. The chronically relapsing course and susceptibility to complications and deterioration in the quality of life of patients with lichen planus give this dermatosis the status of a medical and social problem. Objective — to investigate the state of blood circulation in the areas of skin lesions of patients with lichen planus, depending on the stage of the clinical course of dermatosis. Materials and methods. We observed 37 patients with lichen planus with a typical (classical) clinical form (22 men and 15 women) aged 20 to 44 years. The comparison group consisted of 30 apparently healthy individuals, comparable by sex and age. In 19 patients, the progressive stage of dermatosis was diagnosed, in 18 — the stationary stage. The duration of the course of the disease in the subjects ranged from two weeks to six months. In all the examined patients, the microcirculation index (MI), the mean quadratic deviation of the microcirculation indicators, the coefficient of variation (KV), as well as maximum amplitude of slow oscillations (ALF), maximum amplitude of rapid oscillations (AHF), maximum amplitude of pulse oscillations (ACF) were determined. The first component of the active mechanism of regulation of tissue circulation was calculated according to the formula ALF/PM; the second component — according to the formula σ/ALF; the first component of the passive mechanism of modulation of tissue circulation was calculated according to the formula ACF/σ; the second component — according to the formula AHF/σ. In addition, the intravascular resistance ACF/PM · 100 % and the microcirculation efficiency coefficient ALF/(AHF + ACF) were studied. The study was carried out on a Doppler flowmeter Vingmed SD-100 (Sweden). Results and discussion. The obtained results indicate a low level of tissue perfusion, insufficient functioning of tissue blood circulation modulation mechanisms and reduced vasomotor activity of microvessels in the areas of affected skin of patients with lichen planus. It was also established that the modulation of tissue blood circulation was redistributed in the direction of reducing the passive mechanism, that is, in the direction of disturbances of cardiac and respiratory rhythms of fluctuations. Conclusions. In the examined patients with a typical (classical) form of the clinical course of lichen planus, a stagnant­static type of hemodynamics in the dermis was established during the examination by laser Doppler flowmetry in the skin areas affected by a specific papular rash.It has also been proved that in patients with lichen planus, in particular, in skin areas with specific lichenoid lesions, there is a redistribution of modulation of tissue blood circulation towards a decrease in the passive mechanism, that is, towards cardiac and respiratory rhythm disorders of fluctuations.The established disorders of dermal vascularization in the areas of skin lesions of patients with lichen planus expand the understanding of the pathogenesis of this dermatosis and need to be taken into account when developing the tactics of its complex, individualized therapy, which will contribute to increasing the effectiveness of treatment.

Comparison of Intact Fish Skin Graft and Allograft as Temporary Coverage for Full-Thickness Burns: A Non-Inferiority Study.

The extent and depth of burn injury may mandate temporary use of cadaver skin (allograft) to protect the wound and allow the formation of granulation tissue while split-thickness skin grafts (STSGs) are serially harvested from the same donor areas. However, allografts are not always available and have a high cost, hence the interest in identifying more economical, readily available products that serve the same function. This study evaluated intact fish skin graft (IFSG) as a temporary cover to prepare the wound bed for STSG application. Thirty-six full-thickness (FT) 5 × 5 cm burn wounds were created on the dorsum of six anesthetized Yorkshire pigs on day -1. To mimic the two-stage clinical situation, on day 0, wounds were excised down to a bleeding wound bed and a temporary cover (either IFSG or cadaver porcine skin) was applied; then, on day 7, wounds were debrided to a viable wound bed prior to the application of autologous 1.5:1 meshed STSG (mSTSG). Rechecks were performed on days 14, 21, 28, 45, and 60 with digital images, non-invasive measurements, and punch biopsies. The IFSG created a granulated wound bed receptive to the application of an mSTSG. FT burn wounds treated with an IFSG had similar outcome measures, including contraction rates, trans-epidermal water loss (TEWL) measurements, hydration, and blood perfusion levels, compared to cadaver skin-treated burn wounds. Pathology scoring indicated significant differences between the allograft- and IFSG-treated wounds on day 7, with the IFSG having increased angiogenesis, granulation tissue formation, and immune cells. Pathology scoring indicated no significant differences once mSTSGs were applied to wounds. The IFSG performed as well as cadaver skin as a temporary cover and was not inferior to the standard of care, suggesting the potential to transition IFSGs into clinical use for burns.

Comparison of computed tomography perfusion and magnetic resonance dynamic susceptibility contrast perfusion-weighted imaging in canine brain.

Brain perfusion allows for the evaluation of cerebral hemodynamics, particularly in brain infarcts and tumors. Computed tomography (CT) perfusion (CTP) provides reliable data; however, it has a limited scan field of view and radiation exposure. Magnetic resonance (MR) perfusion provides detailed imaging of small structures and a wide scan field of view. However, no study has compared CTP and MR perfusion and assessed the correlation between the perfusion parameters measured using CTP and MR perfusion. The aim of the present study was to assess the correlation and agreement of the cerebral perfusion derived from dynamic susceptibility contrast (DSC)-MRI and CTP in dogs. In this crossover design study, the cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time, and time to peak were measured in the temporal cerebral cortex, caudate nucleus, thalamus, piriform lobe, and hippocampus using CTP and DSC-MRI in six healthy beagle dogs and a dog with a pituitary tumor. On the color map of healthy beagles, blood vessels and the perivascular brain parenchyma appeared as red-green, indicating high perfusion, and the areas distant from the vessels appeared as green-blue, indicating low perfusion levels in CTP and DSC-MRI. CTP parameters were highest in the piriform lobe (CBF = 121.11 ± 12.78 mL/100 g/min and CBV = 8.70 ± 2.04 mL/100 g) and lowest in the thalamus (CBF = 63.75 ± 25.24 mL/100 g/min and CBV = 4.02 ± 0.55 mL/100 g). DSC-MRI parameters were also highest in the piriform lobe (CBF = 102.31 ± 14.73 mL/100 g/min and CBV = 3.17 ± 1.23 mL/100 g) and lowest in the thalamus (CBF = 37.73 ± 25.11 mL/100 g/min and CBV = 0.81 ± 0.44 mL/100 g) although there was no statistical correlation in the quantitative perfusion parameters between CTP and DSC-MRI. In a dog with a pituitary tumor, the color map of the tumor appeared as a red scale, indicating high perfusion and higher CBF and CBV on CTP (149 mL/100 g and 20 mL/100 g/min) and on DSC-MRI (116.3 mL/100 g and 15.32 mL/100 g/min) compared to those measured in healthy dogs. These findings indicate that DSC-MRI and CTP maps exhibit comparability and interchangeability in the assessment of canine brain perfusion.

Insights into hippocampal perfusion using high-resolution, multi-modal 7T MRI

We present a comprehensive study on the non-invasive measurement of hippocampal perfusion. Using high-resolution 7 tesla arterial spin labeling (ASL) data, we generated robust perfusion maps and observed significant variations in perfusion among hippocampal subfields, with CA1 exhibiting the lowest perfusion levels. Notably, these perfusion differences were robust and already detectable with 50 perfusion-weighted images per subject, acquired in 5 min. To understand the underlying factors, we examined the influence of image quality metrics, various tissue microstructure and morphometric properties, macrovasculature, and cytoarchitecture. We observed higher perfusion in regions located closer to arteries, demonstrating the influence of vascular proximity on hippocampal perfusion. Moreover, ex vivo cytoarchitectonic features based on neuronal density differences appeared to correlate stronger with hippocampal perfusion than morphometric measures like gray matter thickness. These findings emphasize the interplay between microvasculature, macrovasculature, and metabolic demand in shaping hippocampal perfusion. Our study expands the current understanding of hippocampal physiology and its relevance to neurological disorders. By providing in vivo evidence of perfusion differences between hippocampal subfields, our findings have implications for diagnosis and potential therapeutic interventions. In conclusion, our study provides a valuable resource for extensively characterizing hippocampal perfusion.

The state of microcirculation in patients with periodontal diseases and disorders of the occlusal relationships of the dentition

Background. The study of microcirculation disorders, as one of the key factors in the pathogenesis of periodontal diseases, is relevant in clinical dentistry. Premature contacts, acting as provoking factors for occlusal disorders, cause overload of individual teeth and aggravate the severity of inflammatory periodontal pathology. Objective registration of capillary blood flow and associated changes in the microvessels of the arteriolar and venular units in patients with periodontopathies and occlusal dis-orders will allow us to assess the degree and nature of tissue blood flow disorders in the gum tissue.Goal. Increasing the efficiency of diagnosing microcirculatory disorders in periodontal tissues in patients with chronic generalized mild periodontitis and disorders of the occlusal relationships of the dentition.Materials and methods. Using laser Doppler flowmetry (LDF), the state of mi-crocirculation in the periodontium was studied in 78 people aged 21–35 years with intact dentition and physiological occlusion, of which 33 people (group 1) had clinically healthy periodontium and the absence of occlusal disorders (group 1), with generalized chronic pulmonary periodontitis degree and premature occlusal contacts – 45 people (group 2). The microcirculation index (M), standard deviation (σ), and coefficient of variation (КV) were assessed. To obtain objective diagnostic data, amplitude-frequency analysis of the harmonic rhythms of LDF-grams was used with spectral decomposition into harmonic components of physiological oscillations of tissue blood flow (wavelet analysis).Results. In patients of group 2, in comparison with patients of group 1, a decrease in the level of periodontal blood perfusion, a reduction in the fluctuation of erythro-cyte flow and vasomotor activity of microvessels is determined, while a decrease in “active” and an increase in «passive» modulation of tissue blood flow contributes to an increase in the volume of circulating blood at arteriovenular anastomoses when the intensity of blood flow through the vessels of the capillary bed decreases.Conclusions. Patients of group 1 were diagnosed with a normoemic type of LDF-gram, which provides a relatively high degree of intensity of tissue blood flow, balance of regulatory mechanisms, and optimal trophism of periodontal tissues. In patients of group 2 with a spastic type of LDF-gram, characterized by a reduced level of perfusion, flux, vasomotor activity of microvessels, indicators of tissue blood flow and trophic function are significantly reduced.

Tissue oxidative metabolism and microhemodynamics of the skin in rats exposed to stress factors of different durations and combinations

BACKGROUND: Changes in tissue oxidative metabolism under the action of stressors of different durations have not been studied. The relationship between NADH and FAD coenzymes and the microcirculatory bed remains unclear.&#x0D; AIM: This study aimed to identify the features of the reaction of skin microhemodynamics and tissue oxidative metabolism in rats exposed to acute and chronic stress factors of different durations and their combinations.&#x0D; MATERIALS AND METHODS: The experiment was performed on 100 male Wistar rats weighing 200–220 g. The animals were divided into five groups of 20 rats. The first control group and the second and third groups were exposed to acute stress (AS) and chronic hypokinetic stress (HS), respectively; the fourth group (AS-HS) was previously exposed to AS (on the first day) and then to HS (1–10 days); and the fifth group (for 10 days of the HS, then the effect of the AS on day 10). On day 10, the indicators of tissue oxidative metabolism and skin microhemodynamics were recorded.&#x0D; RESULTS: AS and HS increased the requirement of cells for ATP and contributed to the predominance of oxidative phosphorylation over other processes, as indicated by an increase in FAD. AS-HS significantly changed oxidative metabolism, separating oxidative phosphorylation and activating glycolysis. HS-AS did not cause such changes. AS increased the microcirculation index and reduced the coefficient of variation, and HS reduced the microcirculation index and increased the mean square deviation. AS–HS significantly increased the microcirculation index, and HS-AS increased the mean square deviation and coefficient of variation but reduced the microcirculation index.&#x0D; CONCLUSIONS: AS and HS increase the requirement of cells for ATP and contribute to the predominance of oxidative phosphorylation over other processes. AS-HS modifies oxidative metabolism by disconnecting oxidative phosphorylation and activating glycolysis. HS-AS depletes the metabolic reserves of the body. AS-HS rearranges metabolism along the path of glycolysis, protecting against stress factors and preventing the development of oxidative stress. AS leads to hyperemia and stasis of blood circulation in the microarray, reducing the vasomotor activity of the vessels. HS inhibits the level of tissue perfusion and reduces the inflow of arterial blood into the microcirculatory bed and the outflow of venous blood, leading to spastic, stagnant phenomena and stasis. AS-HS reduces vasoconstriction, preparing a microcirculatory bed for prolonged hypokinesia. HS-AS levels vasodilation and improves the parameters of skin microhemodynamics (mean square deviation and coefficient of variation).

Longitudinal Brain Perfusion and Symptom Presentation Following Pediatric Concussion: A Pediatric Concussion Assessment of Rest and Exertion+MRI (PedCARE+MRI) Substudy.

Emerging evidence suggests that advanced neuroimaging modalities such as arterial spin labelling (ASL) might have prognostic utility for pediatric concussion. This study aimed to: 1) examine group differences in global and regional brain perfusion in youth with concussion or orthopedic injury (OI) at 72 h and 4 weeks post-injury; 2) examine patterns of abnormal brain perfusion within both groups and their recovery; 3) investigate the association between perfusion and symptom burden within concussed and OI youths at both time-points; and 4) explore perfusion between symptomatic and asymptomatic concussed and OI youths. Youths ages 10.00-17.99 years presenting to the emergency department with an acute concussion or OI were enrolled. ASL-magnetic resonance imaging scans were conducted at 72 h and 4 weeks post-injury to measure brain perfusion, along with completion of the Health Behavior Inventory (HBI) to measure symptoms. Abnormal perfusion clusters were identified using voxel-based z-score analysis at each visit. First, mixed analyses of covariance (ANCOVAs) investigated the Group*Time interaction on global and regional perfusion. Post hoc region of interest (ROI) analyses were performed on significant regions. Second, within-group generalized estimating equations investigated the recovery of abnormal perfusion at an individual level. Third, multiple regressions at each time-point examined the association between HBI and regional perfusion, and between HBI and abnormal perfusion volumes within the concussion group. Fourth, whole-brain one-way ANCOVAs explored differences in regional and abnormal perfusion based on symptomatic status (symptomatic vs. asymptomatic) and OIs at each time-point. A total of 70 youths with a concussion [median age (interquartile range; IQR) = 12.70 (11.67-14.35), 47.1% female] and 29 with an OI [median age (IQR) = 12.05 (11.18-13.89), 41.4% female] were included. Although no Group effect was found in global perfusion, the concussion group showed greater adjusted perfusion within the anterior cingulate cortex/middle frontal gyrus (MFG) and right MFG compared with the OI group across time-points (ps ≤ 0.004). The concussion group showed lower perfusion within the right superior temporal gyrus at both time-points and bilateral occipital gyrus at 4 weeks, (ps ≤ 0.006). The number of hypoperfused clusters was increased at 72 h compared with 4 weeks in the concussion youths (p < 0.001), but not in the OIs. Moreover, Group moderated the HBI-perfusion association within the left precuneus and superior frontal gyrus at both time-points, (ps ≤ 0.001). No association was found between HBI and abnormal perfusion volume within the concussion group at any visits. At 4 weeks, the symptomatic sub-group (n = 10) showed lower adjusted perfusion within the right cerebellum and lingual gyrus, while the asymptomatic sub-group (n = 59) showed lower adjusted perfusion within the left calcarine, but greater perfusion within the left medial orbitofrontal cortex, right middle frontal gyrus, and bilateral caudate compared with OIs. Yet, no group differences were observed in the number of abnormal perfusion clusters or volumes at any visit. The present study suggests that symptoms may be associated with changes in regional perfusion, but not abnormal perfusion levels.