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Context: As blood flow restriction gains popularity across different populations (eg, young and older adults) and settings (eg, clinical and sports rehabilitation), the accuracy of blood flow restricted percentage becomes crucial. We aimed to compare manually measured arterial occlusion pressure (AOP) among young adults to understand whether lower limb composition affects the pressure required to achieve AOP. The results will shed light on the adequacy of published calculations used to estimate AOP in practical and research settings. Design: An observational cross-sectional study design was implemented to examine the relationship between lower limb composition, lower limb circumference, and measured AOP. Methods: Twenty-two participants (12 males, 26 [4] y, 1.74 [0.07] m, 73.2 [12.5] kg) underwent a whole-body Dual-energy X-ray Absorptiometry scan before AOP (in millimeters of mercury) and lower limb circumference (in centimeters) were determined. In a supine position, a 10-cm wide cuff was manually inflated on the dominant leg to the point where a pulse could no longer be detected by a Doppler ultrasound of the posterior tibial artery to determine AOP. Lower limb composition (fat, muscle, and bone mass [in grams]) was obtained from the Dual-energy X-ray Absorptiometry scan. Results: Lower limb muscle mass had a moderate negative relationship with AOP (r2 =.433, β = −0.004) and a moderate positive relationship with lower limb circumference (r2 =.497, β = 0.001). Lower limb circumference had the weakest relationship with AOP (r2 =.316, β = 0.050) of all measures. Conclusions: The reported relationships between lower limb muscle mass, lower limb circumference, and AOP suggest that as muscle mass increases, lower limb circumference also increases, yet AOP decreases. This implies that limb circumference should not be used as the primary measure for calculating AOP within the sampled population. We recommend individually measuring AOP when implementing blood flow restriction in all exercise modalities. [ABSTRACT FROM AUTHOR]

It is important to understand the dynamics of red blood cells (RBCs) in blood flow. This requires the formulation of coarse-grained RBC models that reproduce the hydrodynamic properties of blood accurately. One of the models that successfully reproduces the rheology and morphology of blood has been proposed by Fedosov et al. [Comput. Methods Appl. Mech. Eng. 199, 1937–1948 (2010)]. The proposed RBC model contains several parameters whose values are determined by either various experiments or physical requirements. In this study, we developed a new method of determining parameter values precisely from the fluctuations of the RBC membrane. Specifically, we studied the relationship between the spectra of the fluctuations and model parameters. Characteristic peaks were observed in the spectra, whose peak frequencies were dependent on the parameter values. In addition, we investigated the spectra of the radius of gyration. We identified the peaks originating from the spring potential and the volume-conserving potential appearing in the spectra. These results lead to the precise experimental determination of the parameters used in the RBC model. [ABSTRACT FROM AUTHOR]

In the present study, a Caputo–Fabrizio (C–F) time-fractional derivative is introduced to the governing equations to present the flow of blood and the transport of magnetic nanoparticles (MNPs) through an inclined porous artery with mild stenosis. The rheology of blood is defined by the non-Newtonian visco-elastic Jeffrey fluid. The transport of MNPs is used as a drug delivery application for cardiovascular disorder therapy. The momentum and transport equations are solved analytically by using the Laplace transform and the finite Hankel transform along with their inverses, and the solutions are presented in the form of Laplace convolutions. To display the solutions graphically, the Laplace convolutions are solved using the numerical integration technique. The study presents the impacts of different governing parameters on blood and MNP velocities, volumetric flow rate, flow resistance, and skin friction. The study demonstrates that blood and MNP velocities boost with an increase in the fractional order parameter, Darcy number, and Jeffrey fluid parameter. The volumetric flow rate decreases and flow resistance increases with enhancement in stenosis height. The non-symmetric shape of stenosis and the rheology of blood decrease skin friction, whereas enhancement in MNP concentration increases skin friction. A comparison of the present result with the previous work shows excellent agreement. The present study will be beneficial for the field of medical science to further study atherosclerosis therapy and other similar disorders. [ABSTRACT FROM AUTHOR]

Clinical Scenario: Stress fractures are one of the most common injuries in athletes. Unfortunately, they are hard to diagnose, require multiple radiology exams and follow-up which leads to more exposure to radiation and an increase in cost. Stress fractures that are mismanaged can lead to serious complications and poorer outcomes for the athlete. During the rehabilitation process, it would be beneficial to be able to monitor the healing of fractures to know when it is safe to gradually allow a patient to a return to sport because the return to activity is not usually objective and based on pain level. Clinical Question: Can infrared thermography (IRT) be a useful tool to measure the pathophysiological state of the fracture healing? The aim of this critically appraised topic is to analyze the current evidence of IRT for measuring the temperature change in fractures to provide recommendations for medical practitioners. Summary of Key Findings: For this critically appraised topic, we examined 3 articles that compared medical imaging and IRT over multiple time points during the follow-up. The 3 articles concluded that a 1 °C asymmetry in temperature followed by a return to normal (less than 0.3 °C) temperature during the healing process of fractures can be monitored using IRT. Clinical Bottom Line: Once the patient has been diagnosed with a fracture, IRT can safely be used to monitor the evolution of a fracture. When the thermogram progresses from a hot thermogram to a cold thermogram, the healing is considered good enough to return to sport. Strength of Recommendation: Grade 2 evidence exists to support IRT being used by clinicians to monitor fracture healing. Due to the limited research and novelty of the technology, the current recommendations are for following the treatment of the fracture once the initial diagnosis is made. [ABSTRACT FROM AUTHOR]

This study investigated the effect of cryotherapy with carbon dioxide hydrate (CDH) on fatigue recovery of neuromuscular function and muscle blood circulation. Fourteen young males randomly received three types of 20-min recovery interventions (cryotherapy with CDH [CDH-condition] or normal ice [ICE-condition], or quiet sitting at room temperature [CON-condition]) 5 min following a fatiguing task (50 maximal effort isotonic contractions) on three separate days. The isotonic peak power of the knee extensors at 35 min after the fatiguing task in the CDH-condition (95% of baseline) was greater than that in the other conditions (82–89% of baseline; p ≤ 0.031). In addition, at 25 and 35 min after the fatiguing task, the changes in haemoglobin concentration of the knee extensors from before the fatiguing task in the CON-condition (2.5 and 3.0 μmol/L) were different from those in the ICE-condition (−1.4 and −1.3 μmol/L; p ≤ 0.004) but comparable to those in the CDH-condition (1.1 and 0.7 μmol/L; p ≥ 0.060), respectively. These findings suggest that cryotherapy with CDH did not lower the blood volume following the intervention, unlike that with normal ice, and promoted greater immediate recovery of muscle power from neuromuscular fatigue compared with cryotherapy with ice or passive rest. [ABSTRACT FROM AUTHOR]

We develop a computational algorithm based on a diffuse interface approach to study the design of bioartificial organ scaffold architectures. These scaffolds, composed of poroelastic hydrogels housing transplanted cells, are linked to the patient's blood circulation via an anastomosis graft. Before entering the scaffold, the blood flow passes through a filter, and the resulting filtered blood plasma transports oxygen and nutrients to sustain the viability of transplanted cells over the long term. A key issue in maintaining cell viability is the design of ultrafiltrate channels within the hydrogel scaffold to facilitate advection-enhanced oxygen supply ensuring oxygen levels remain above a critical threshold to prevent hypoxia. In this manuscript, we develop a computational algorithm to analyze the plasma flow and oxygen concentration within hydrogels featuring various channel geometries. Our objective is to identify the optimal hydrogel channel architecture that sustains oxygen concentration throughout the scaffold above the critical hypoxic threshold. The computational algorithm we introduce here employs a diffuse interface approach to solve a multi-physics problem. The corresponding model couples the time-dependent Stokes equations, governing blood plasma flow through the channel network, with the time-dependent Biot equations, characterizing Darcy velocity, pressure, and displacement within the poroelastic hydrogel containing the transplanted cells. Subsequently, the calculated plasma velocity is utilized to determine oxygen concentration within the scaffold using a diffuse interface advection-reaction-diffusion model. Our investigation yields a scaffold architecture featuring a hexagonal network geometry that meets the desired oxygen concentration criteria. Unlike classical sharp interface approaches, the diffuse interface approach we employ is particularly adept at addressing problems with intricate interface geometries, such as those encountered in bioartificial organ scaffold design. This study is significant because recent developments in hydrogel fabrication make it now possible to control hydrogel rheology and utilize computational results to generate optimized scaffold architectures. Author summary: Bioartificial organ is an engineered device made of living cells and a biocompatible scaffold that can be implanted or integrated into a human body to replace a natural organ, or to augment a specific organ function. The biocompatible scaffold serves as the structural foundation, embedding cells and growth factors to form substitute tissue. A key challenge in bioartificial organ design is ensuring the long-term survival of transplanted cells. Specifically, a critical challenge is creating a hydrogel architecture with ultrafiltrate channels that act as pathways to deliver oxygen and nutrients to the cells, supporting their sustained viability. In this work, we developed a mathematical and computational framework to investigate optimal hydrogel architecture and oxygen supply to transplanted cells. Our findings show that a hexagonal channel architecture significantly outperforms both the commonly used vertical channels and branching channel designs, providing a substantial increase in oxygen delivery to the cells. In the hexagonal architecture, oxygen concentration remains above the critical threshold for hypoxia throughout the scaffold, which is not achieved with other designs. This is particularly important given recent advances in hydrogel fabrication, allowing for precise control of hydrogel elasticity and rheology, making these results valuable for developing improved scaffold designs. [ABSTRACT FROM AUTHOR]

This study investigated the effect of limb occlusion pressure (LOP) position on exercise performance, cardiovascular responses, and perceptual experiences during seated bilateral leg extensions with and without blood flow restriction (BFR). Thirty resistance-trained males (age: 22 ± 2 years; weight: 74.4 ± 13.6 kg; height: 177.4 ± 6.4 cm; BMI: 23.5 ± 3.3 kg/m2) participated. Each performed exercise to failure (4 sets, 30% 1RM, 1 min rest) in three conditions: Supine LOP-BFR, Seated LOP-BFR, and no-BFR. BFR was applied at 60% LOP. Significant interaction effects were found for RPE (p = 0.021, d = 0.76), RPD (p < 0.01, d = 1.72), and DOMS (p < 0.01, d = 2.28). Statistically significant fewer repetitions were completed in Supine LOP-BFR vs. no-BFR (p < 0.01, d = 0.5), Seated LOP-BFR vs. no-BFR (p < 0.01, d = 1.0), and Seated LOP-BFR vs. Supine LOP-BFR (p < 0.01, d = 0.6). RPE was higher in Seated LOP-BFR vs. no-BFR (p < 0.01, d = 0.52). RPD was higher in Supine LOP-BFR vs. no-BFR (p < 0.01, d = 0.62) and Seated LOP-BFR vs. no-BFR (p < 0.01, d = 1.25). DOMS was higher in Supine LOP-BFR vs. no-BFR (p < 0.01, d = 0.77) and Seated LOP-BFR vs. no-BFR (p < 0.01, d = 3.52). Seated LOP-BFR increased perceptual demands and reduced repetitions compared to Supine LOP-BFR. Both LOP-BFR conditions reduced repetitions compared to no-BFR without affecting cardiovascular measures. [ABSTRACT FROM AUTHOR]

Recently, we identified myeloid‐derived growth factor (MYDGF) as a blood flow‐induced angiocrine signal that promotes human and mouse hepatocyte proliferation and survival. Here, we review literature reporting changes in blood flow after partial organ resection in the liver, lung, and kidney, and we describe the angiocrine signals released by endothelial cells (ECs) upon blood flow alterations in these organs. While hepatocyte growth factor (HGF) and MYDGF are important angiocrine signals for liver regeneration, by now, angiocrine signals have also been reported to stimulate hyperplasia and/or hypertrophy during the regeneration of lungs and kidneys. In addition, angiocrine signals play a critical role in tumor growth. Understanding the mechano‐elastic properties and flow‐mediated alterations in the organ‐specific microvasculature is crucial for therapeutic approaches to maintain organ health and initiate organ renewal. [ABSTRACT FROM AUTHOR]

Coronary artery disease (CAD) is characterized by narrowing and subsequent blockade of coronary arteries, and imposes a significant health and economic burden. Stent and scaffold devices are introduced in advanced CAD to improve vascular stability and restore blood flow. Although in vitro flow systems like the Chandler loop have been developed to enhance the understanding of interactions between device materials, their coatings, and vascular cells, imaging-based in vitro analysis of device performance is limited. In this study, we established a novel stent flow chamber system designed to assess the thrombogenicity of bioresorbable magnesium scaffold (RMS) and stent materials in vitro. Additionally, we compared the thrombogenicity – an important clinical parameter in stent performance – of the Magmaris-316 L stainless steel stent with its predecessors, Magmaris RMS and a prototype of the third-generation RMS (DREAMS 3G). Analysis of platelet adhesion and coverage of the different devices under flow conditions demonstrated that the Magmaris RMS exhibits reduced thrombogenicity compared to the Magmaris-316 L stainless steel stent. Moreover, thrombogenicity of the DREAMS 3G prototype, composed of BIOmag material, is further decreased compared to its predecessors. The observed reduction in thrombogenicity of the DREAMS 3G prototype in vitro suggests additional improvements in clinical safety and efficacy, highlighting its promise for treating CAD. Future research on this prototype may thus open avenues for analyzing other blood components and patient-derived endothelial cells. In line with the 3R principles, this approach may also help reduce the need for animal testing. [ABSTRACT FROM AUTHOR]

Leptomeningeal collaterals (LMCs) are crucial in mitigating the impact of acute ischemic stroke (AIS) by providing alternate blood flow routes when primary arteries are obstructed. This article explores the evolutionary pathophysiology of LMCs, highlighting their critical function in stroke and the genetic and molecular mechanisms governing their development and remodelling. We address the translational challenges of applying animal model findings to human clinical scenarios, emphasizing the need for further research to validate emerging therapies—such as pharmacological agents, gene therapy and mechanical interventions—in clinical settings, aimed at enhancing collateral perfusion. Computational modelling emerges as a promising method for integrating experimental data, which requires precise parameterization and empirical validation. We introduce the ‘Evolucollateral Dynamics’ hypothesis, proposing a novel framework that incorporates evolutionary biology principles into therapeutic strategies, offering new perspectives on enhancing collateral circulation. This hypothesis emphasizes the role of genetic predispositions and environmental influences on collateral circulation, which may impact therapeutic strategies and optimize treatment outcomes. Future research must incorporate human clinical data to create robust treatment protocols, thereby maximizing the therapeutic potential of LMCs and improving outcomes for stroke patients. [ABSTRACT FROM AUTHOR]

Atherosclerosis is one of the important diseases of the circulatory system because atherosclerotic plaques cause significant disruption of blood flow. Therefore, it is very important to properly understand these processes and skillfully simulate blood flow. In our work, we consider blood flow through an abdominal aorta with iliac arteries, assuming that the right iliac artery is narrowed by an atherosclerotic lesion. Blood flow is simulated using the laminar, standard k - ω and standard k - ϵ models. The obtained results show that despite the use of identical initial conditions, the distribution of velocity flow and wall shear stress depends on the choice of flow simulation model. For the k - ϵ model, we obtain higher values of speed and wall shear stress on atherosclerotic plaque than in the other two models. The laminar and k - ω models predict larger areas where reverse blood flow occurs in the area behind the atherosclerotic lesion. This effect is associated with negative wall shear stress. These two models give very similar results. The results obtained by us, and those reported in the literature, indicate that k - ω model is the most suitable for blood flow analysis. [ABSTRACT FROM AUTHOR]

Ischemic diseases are characterized by obstruction of blood flow to the respective organs, of which ischemia of the heart and brain are the most prominent manifestations with shared pathophysiological mechanisms and risk factors. While most revascularization therapies aim to restore blood flow, this can be challenging due to the limited therapeutic window available for treatment approaches. For a very long time, mesenchymal stromal cells have been used to treat cerebral and cardiac ischemia. However, their application is restricted either by inefficient mode of delivery or the low cell survival rates following implantation into the ischemic microenvironment. Nonetheless, several studies are currently focusing on using of mesenchymal stromal cells engineered to overexpress therapeutic genes as a cell-based gene therapy to restore angiogenesis. This review delves into the utilization of MSCs for angiogenesis and the applications of engineered MSCs for the treatment of cardiac and cerebral ischemia. Moreover, the safety issues related to the genetic modification of MSCs have also been discussed. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to examine the spatiotemporal coherence of capillary lumen fluctuations in relation to spatial variations in the pericyte lining in the cortex of anesthetized mice. Methods: Two‐photon microscopic angiography data (previously published) were reanalyzed, and spatial variations in capillary diameter fluctuations at rest and in capillary lining with vascular mural cells were measured along capillary centerlines. Results: Relatively large diameters of the capillaries (5.5 μm) coincided with a dense pericyte lining, while small capillaries (4.3 μm) had a sparse pericyte lining. Temporal variations had a frequency of about 0.1 Hz with an amplitude of 0.5 μm, which were negatively correlated with pericyte lining density. Spatial frequency analysis further revealed a common pattern of spatial variations in capillary diameter and pericyte lining, but temporal variations differed. The temporal variations in capillary lumens were locally distinct from those in neighboring locations, suggesting intrinsic fluctuations independent of the pericyte lining. Conclusions: Capillary lumens in the brain exhibit slow microfluctuations that are independent of pericyte lining. These microfluctuations could affect the distribution of flowing blood cells and may be important for homogenizing their distribution in capillary networks. [ABSTRACT FROM AUTHOR]

Laser Doppler flowmetry (LDF) is a well‐established technique for the investigation of tissue microcirculation. Compared to skin, the use in the human brain is sparse. The measurement of cerebral microcirculation in neurointensive care and during neurosurgery is challenging and requires adaptation to the respective clinical setting. The aim of the review is to present state of the art and progress in neurosurgery and neurointensive care where LDF has proven useful and can find clinical importance in the investigation of cerebral microcirculation. The literature in the field is summarized and recent technical improvements regarding LDF systems and fiber optical probe designs for neurosurgical and neurocritical care described. By combining two signals from the LDF unit, the measurement of the microcirculation (Perfusion) and gray whiteness (TLI) of the brain tissue, the full potential of the device is achieved. For example, a forward‐looking LDF‐probe detects high‐risk hemorrhage areas and gray‐white matter boundaries along intraoperative trajectories during stereotactic neurosurgery. Proof of principles are given for LDF as a guidance tool in deep brain stimulation implantation, brain tumor needle biopsies, and as long‐term monitoring device in neurocritical care. With well‐designed fiber optical probes, surgical fixation, and signal processing for movement reduction, LDF monitoring of the cerebral microcirculation is successful up to 10 days. The use of LDF can be combined with other physiological measurement techniques, for example, fluorescence spectroscopy for identification of glioblastoma during tumor surgery. Fiber optics can also be used during magnetic resonance imaging (MRI). Despite the many advantages, fiber optical LDF has not yet reached its full potential in clinical neuro‐applications. Multicenter studies are required to further evaluate LDF in neurosurgery and neurointensive care. In conclusion, the present status of LDF in neurosurgery and neurointensive care has been reviewed. By combining Perfusion and TLI with tailored probe designs the full potential of LDF can be achived in measuring cerebral microcirculation. This includes guidance during DBS implantation and needle biopsies, and long‐term monitoring in neurocritical care. [ABSTRACT FROM AUTHOR]

Background/Objectives: The aim of this study was to evaluate the choroidal vascular response using optical coherence tomography (OCT) in patients with chronic central serous chorioretinopathy (CSCR) during transient increases in blood pressure. Methods: This observational, case–control study enrolled chronic CSCR patients and age-matched healthy controls. OCT scans of the macula were performed at rest and during hand-grip (HG) isometric exercise. Mean ocular perfusion pressure (MOPP) and subfoveal choroidal thickness (SCT) were measured at baseline and during stress. Quantitative OCT assessment included the bright area (BA, stroma), dark area (DA, vascular lumen), and total choroidal area (CA). The choroidal vascularity index (CVI) was calculated as DA/CA to assess vascular response to stress. A comparative analysis between CSCR patients and controls was conducted. Conclusions: MOPP was significantly higher (p = 0.008) at baseline in CSCR patients and further increased under stress compared to controls. SCT and CA were both significantly higher in CSCR patients than in healthy subjects at rest and under stress (p < 0.001), but no change occurred after HG. A significant decrease in CVI (p = 0.005) was noted in controls under stress, but not in CSCR patients. Additionally, a negative correlation between CVI and MOPP was found in healthy subjects (−0.648; p = 0.043). The study demonstrated a choroidal vasoconstrictive response to stress in healthy subjects, as evidenced by a decrease in CVI, but not in CSCR patients. This suggests that CSCR patients may experience impaired choroidal blood flow regulation, resulting in potentially higher perfusion pressures during stress without compensatory vasoconstriction, potentially affecting the choriocapillaris. [ABSTRACT FROM AUTHOR]

Non-contact heart rate monitoring from facial videos utilizing remote photoplethysmography (rPPG) has gained significant traction in remote health monitoring. Given that rPPG captures the dynamic blood flow within the human body and constitutes a time-series signal characterized by periodic properties, this study introduced a three-dimensional convolutional neural network (3D CNN) designed to simultaneously address long-term periodic and short-term temporal characteristics for effective rPPG signal extraction. Firstly, differential operations are employed to preprocess video data, enhancing the face's dynamic features. Secondly, building upon the 3D CNN framework, multi-scale dilated convolutions and self-attention mechanisms were integrated to enhance the model's temporal modeling capabilities further. Finally, interpolation techniques are applied to refine the heart rate calculation methodology. The experiments conducted on the UBFC-rPPG dataset indicate that, compared with the existing optimal algorithm, the average absolute error (MAE) and the root mean square error (RMSE) realized significant enhancements of approximately 28% and 35%. Additionally, through comprehensive analyses such as cross-dataset experiments and complexity analyses, the validity and stability of the proposed algorithm in the task of heart rate estimation were manifested. [ABSTRACT FROM AUTHOR]

Remote photoplethysmography (rPPG) refers to a non-contact technique that measures heart rate through analyzing the subtle signal changes of facial blood flow captured by video sensors. It is widely used in contactless medical monitoring, remote health management, and activity monitoring, providing a more convenient and non-invasive way to monitor heart health. However, factors such as ambient light variations, facial movements, and differences in light absorption and reflection pose challenges to deep learning-based methods. To solve these difficulties, we put forward a measurement network of heart rate based on multiscale features. In this study, we designed and implemented a dual-branch signal processing framework that combines static and dynamic features, proposing a novel and efficient method for feature fusion, enhancing the robustness and reliability of the signal. Furthermore, we proposed an alternate time-shift module to enhance the model's temporal depth. To integrate the features extracted at different scales, we utilized a multiscale feature fusion method, enabling the model to accurately capture subtle changes in blood flow. We conducted cross-validation on three public datasets: UBFC-rPPG, PURE, and MMPD. The results demonstrate that MDAR not only ensures fast inference speed but also significantly improves performance. The two main indicators, MAE and MAPE, achieved improvements of at least 30.6% and 30.2%, respectively, surpassing state-of-the-art methods. These conclusions highlight the potential advantages of MDAR for practical applications. [ABSTRACT FROM AUTHOR]

The muscle metaboreflex effect on pulmonary ventilation (V̇E) regulation is more apparent during rhythmic exercise than rest, possibly because this reflex interacts with other mechanisms regulating V̇E during voluntary contractions, such as central command. Therefore, we tested whether one part of central command, the descending component of motor execution (i.e., descending motor drive), and the muscle metaboreflex interact synergistically to regulate V̇E. Thirteen healthy adults (9 men) completed four experiments in random order under isocapnia. The muscle metaboreflex was activated by rhythmic handgrip exercise at 60% maximal voluntary contraction (MVC) force with the dominant hand. Then, the muscle metaboreflex remained active during a 4-min recovery period via postexercise circulatory occlusion (PECO), or it was inactivated, maintaining free blood flow to the dominant upper limb. During the last 2 min of the handgrip exercise recovery, participants either performed rhythmic voluntary plantar flexion with the dominant leg at 30% MVC torque to generate descending motor drive or the dominant leg's calf muscles were involuntarily activated by electrical stimulation at a similar torque level (i.e., without descending motor drive). V̇E increased to a similar level during handgrip exercise in all conditions (≈22 L/min, P = 0.364). PECO maintained V̇E elevated above recovery with free blood flow (≈17 L/min vs. ≈13 L/min, P = 0.009). However, voluntary and involuntary plantar flexion with or without PECO evoked similar V̇E responses (Δ ≈ 4 L/min, P = 0.311). Therefore, an interaction between descending motor drive and muscle metaboreflex is not ubiquitous for V̇E regulation during rhythmic exercise. NEW & NOTEWORTHY: Voluntary (i.e., with descending motor drive) and involuntary (i.e., no descending motor drive) plantar flexion elicited similar ventilatory responses when postexercise circulatory occlusion was or was not used in an upper limb. These results indicate that the descending motor drive component of the central command and the muscle metaboreflex do not interact to regulate pulmonary ventilation during rhythmic exercise, which suggests that a supposed interaction between central command-muscle metaboreflex is more complex than previously thought. [ABSTRACT FROM AUTHOR]

Heat transfer in the human eyeball, a complex organ, is significantly influenced by various pathophysiological and external parameters. Particularly, heat transfer critically affects fluid behavior within the eye and ocular drug delivery processes. Overcoming the challenges of experimental analysis, this study introduces a comprehensive three‐dimensional mathematical and computational model to simulate the heat transfer in a realistic geometry. Our work includes an extensive sensitivity analysis to address uncertainties and delineate the impact of different variables on heat distribution in ocular tissues. To manage the model's complexity, we employed a very fast model reduction technique with certified sharp error bounds, ensuring computational efficiency without compromising accuracy. Our results demonstrate remarkable consistency with experimental observations and align closely with existing numerical findings in the literature. Crucially, our findings underscore the significant role of blood flow and environmental conditions, particularly in the eye's internal tissues. Clinically, this model offers a promising tool for examining the temperature‐related effects of various therapeutic interventions on the eye. Such insights are invaluable for optimizing treatment strategies in ophthalmology. [ABSTRACT FROM AUTHOR]

The article presents a semi‐automatic approach to generating structured hexahedral meshes of patient‐specific aortas ailed by aortic dissection. The condition manifests itself as a formation of two blood flow channels in the aorta, as a result of a tear in the inner layers of the aortic wall. Subsequently, the morphology of the aorta is greatly impacted, making the task of domain discretization highly challenging. The meshing algorithm presented herein is automatic for the individual lumina, whereas the tears require user interaction. Starting from an input (triangle) surface mesh, we construct an implicit surface representation as well as a topological skeleton, which provides a basis for the generation of a block‐structure. Thereafter, the mesh generation is performed via transfinite maps. The meshes are structured and fully hexahedral, exhibit good quality and reliably match the original surface. As they are generated with computational fluid dynamics in mind, a fluid flow simulation is performed to verify their usefulness. Moreover, since the approach is based on valid block‐structures, the meshes can be made very coarse (around 1000 elements for an entire aortic dissection domain), and thus promote using solvers based on the geometric multigrid method, which is typically reliant on the presence of a hierarchy of coarser meshes. [ABSTRACT FROM AUTHOR]

AbstractIn this work, we investigate a new deep learning reconstruction method of blood flow velocity within deformed vessels from contrast enhanced X-ray projections and vessel geometry. The principle of the method is to perform linear or nonlinear dimension reductions on the Radon projections and on the mesh of the vessel. These low dimensional projections are then fused to obtain the velocity field in the vessel. The accuracy of the reconstruction method is proved using various neural network architectures with realistic unsteady blood flows. The approach leverages the vessel geometry information and outperforms the simple PCA-net. [ABSTRACT FROM AUTHOR]

This study aimed to assess the impact of protein supplementation and its interaction with calf sex (CS) on the performance, metabolism and physiology of pregnant beef cows. Fifty‐two multiparous Zebu beef cows carrying female (n = 22) and male (n = 30) fetuses were used. Cows were individually housed from day 100 to 200 of gestation and randomly assigned to restricted (RES, n = 26) or supplemented (SUP, n = 26) groups. The RES cows were ad libitum fed a basal diet (corn silage + sugarcane bagasse + mineral mixture), achieving 5.5% crude protein (CP), while SUP cows received the same basal diet plus a protein supplement (40% CP, at 3.5 g/kg of body weight). All cows were fed the same diet during late gestation. Differences were declared at p < 0.05. No significant interaction between maternal nutrition and calf sex was found for maternal outcomes (p ≥ 0.34). The SUP treatment increased the total dry matter (DM) intake (p ≤ 0.01) by 32% and 19% at mid‐ and late‐gestation respectively. The total tract digestibility of all diet components was improved by SUP treatment at day 200 of gestation (p ≤ 0.02), as well as the ruminal microbial CP production (p ≤ 0.01). The SUP treatment increased (p ≤ 0.03) the cows' body score condition, ribeye area, the average daily gain (ADG) of pregnant components (PREG; i.e., weight accretion of cows caused by pregnancy) and the ADG of maternal tissues (i.e., weight accretion discounting the gain related to gestation) in the mid‐gestation. The SUP cows exhibited a lower maternal ADG (p < 0.01) compared to RES cows in late pregnancy. There was a 24% additional gain (p < 0.01) in the PREG components for SUP cows during late gestation, which in turn improved the calf birthweight (p = 0.05). The uterine arterial resistance and pulsatility indexes (p ≤ 0.01) at mid‐gestation were greater for RES cows. In conclusion, protein supplementation during mid‐gestation is an effective practice for improving maternal performance, growth of the gravid uterus and the offspring's birth weight. [ABSTRACT FROM AUTHOR]

Asymmetric bifurcate are common in the vascular system, and circulating tumour cells (CTCs) tend to metastasize at these locations. In this study, the dissipative particle dynamics method is used to simulate the motion of a CTC in an asymmetric microvessel combined with a spring-based network model. Effects of flow rate, the presence of RBCs and haematocrit on the motion of the CTC are investigated. The results indicate that under higher flow rate, the CTC could not adhere to the microvessel and invariably migrated towards the branch exhibiting a higher flow rate. In the presence of RBCs, the initially attached CTC would disassociate from the parent vessel wall under the collisions with them, and it finally enters into the large branch. While at lower flow rates, the RBCs pass over the CTC that is rolling along the top wall of the parent vessel and overtake it, facilitating the CTC adhesion, it ultimately moves into the small branch. At a mediate flow rate, though the attached CTC detaches and enters into the large branch, it would touch the inner wall of the branch. With the haematocrit increasing up to 5.1%, the CTC retains rolling along the vessel wall and is ultimately captured in the small branch. [ABSTRACT FROM AUTHOR]

Background: Ultra‐high dose rate irradiation (≥40 Gy/s, FLASH) has been shown to reduce normal tissue toxicity, while maintaining tumor control compared to conventional dose‐rate radiotherapy. The radiolytic oxygen (O2) depletion (ROD) resulting from FLASH has been proposed to explain the normal tissue protection effect; however, in vivo experiments have not confirmed that FLASH induced global tissue hypoxia. Nonetheless, the experiments reported are based on volume‐averaged measurement, which have inherent limitations in detecting microscopic phenomena, including the potential preservation of stem cells niches due to local FLASH‐induced O2 depletion. Computational modeling offers a complementary approach to understand the ROD caused by FLASH at the microscopic level. Purpose: We developed a comprehensive model to describe the spatial and temporal dynamics of O2 consumption and transport in response to irradiation in vivo. The change of oxygen enhancement ratio (OER) was used to quantify and investigate the FLASH effect as a function of physiological and radiation parameters at microscopic scale. Methods: We considered time‐dependent O2 supply and consumption in a 3D cylindrical geometry, incorporating blood flow linking the O2 concentration ([O2]) in the capillary to that within the tissue through the Hill equation, radial and axial diffusion of O2, metabolic and zero‐order radiolytic O2 consumption, and a pulsed radiation structure. Time‐evolved distributions of [O2] were obtained by numerically solving perfusion‐diffusion equations. The model enables the computation of dynamic O2 distribution and the relative change of OER (δROD) under various physiological and radiation conditions in vivo. Results: Initial [O2] level and the subsequent changes during irradiation determined δROD distribution, which strongly depends on physiological parameters, i.e., intercapillary spacing, ultimately determining the tissue area with enhanced radioresistance. We observed that the δROD/FLASH effect is affected by and sensitive to the interplay effect among physiological and radiation parameters. It renders that the FLASH effect can be tissue environment dependent. The saturation of FLASH normal tissue protection upon dose and dose rate was shown. Beyond ∼60 Gy/s, no significant decrease in radiosensitivity within tissue region was observed. In turn, for a given dose rate, the change of radiosensitivity became saturated after a certain dose level. Pulse structures with the same dose and instantaneous dose rate but with different delivery times were shown to have distinguishable δROD thus tissue sparing, suggesting the average dose rate could be a metric assessing the FLASH effect and demonstrating the capability of our model to support experimental findings. Conclusion: On a macroscopic scale, the modeling results align with the experimental findings in terms of dose and dose rate thresholds, and it also indicates that pulse structure can vary the FLASH effect. At the microscopic level, this model enables us to examine the spatially resolved FLASH effect based on physiological and irradiation parameters. Our model thus provides a complementary approach to experimental methods for understanding the underlying mechanism of FLASH radiotherapy. Our results show that physiological conditions can potentially determine the FLASH efficacy in tissue protection. The FLASH effect may be observed under optimal combination of physiological parameters, not limited to radiation conditions alone. [ABSTRACT FROM AUTHOR]

Objective: The aim of our study was to evaluate the indocyanine green (ICG) retention test as a noninvasive marker of esophageal varices(EV). Methods: The clinical data of patients diagnosed with compensated liver cirrhosis in Tianjin Second People's Hospital between January 2018 and January 2021 were analysed with SPSS 23.0. Result: A total of 144 patients (88 M/56 F, 51.7 ± 11.06 years) were enrolled. The ICG retention at 15 min(ICG-r15), PVD, TBIL, Cholinesterase(CHE), AST to ALT ratio(ARR), APRI, splenic area, Lok index, Park index and liver stiffness measurement in the absent or small EV group were lower than those in the medium or large EV group, while the ICG disappareance rate(ICG-K), Effective hepatic blood flow(EHBF), ALB, PLT, and Platelet to Spleen Diameter Ratio(PSDR) were higher, and the differences were significant (P < 0.05). ICG-r15, splenic area, APRI and PLT were independent predictors for medium or large esophageal varices (OR = 1.115, 1.025, 0.281, and 0.987, respectively,P < 0.05). The predictive value of ICG-r15 for medium or large varices was 17.95%, the specificity was 0.849, and the sensitivity was 0.662, the AUROC was 0.815. The cut-off value of PLT for M/L EV was 113.5, and the specificity and sensitivity were 0.616 and 0.887, the AUROC was 0.759. The AUROC of ICG-r15 combined with PLT was 0.866, which was more superior than others. Conclusion: Although we are far from the replacement of endoscopy, ICG-r15 combined with PLT seems to be able to identify patients with medium or large EV in patients with compensated liver cirrhosis. [ABSTRACT FROM AUTHOR]

Background: The super‐thin skin flap formed by skin and soft tissue expansion has large area and good ductility, so it can be used to repair skin defects. However, because the flap is thin, the blood flow in the dermis of the super‐thin expanded flap is weakened, and flap rupture and necrosis after secondary flap transfer may occur. Objective: To compare the skin thickness difference between the expanded ultrathin flaps injected with concentrated growth factor (CGF) and the blank group or saline group. Methods: From June 2021 to December 2023, 10 patients (44 sites) with large‐area scars or skin tumors were treated, and a single center half randomized controlled trial was conducted. The test site of expander implantation was divided into three groups: intradermal injection of CGF group, normal saline group and blank group. The same amount of expansion was performed every 1–2 weeks, and CGF or normal saline was injected into the dermis every 4 weeks, a total of three times. After 2–3 months of expansion, color Doppler ultrasound was used to measure the skin thickness of each group. Results: Compared with the blank group, the skin thickness of CGF group was 1.75 ± 0.08 mm, and that of BLA blank group was 1.42 ± 0.07 mm, with statistically significant difference (p < 0.0001); In the other group, compared with the saline group, the skin thickness of the CGF group was 1.54 ± 0.08 mm, and the average skin thickness of the saline group was 1.40 ± 0.08 mm, with significant difference between the two groups (p = 0.0067). Conclusion: CGF intradermal injection can increase the skin thickness of super‐thin skin flap in the process of soft tissue expansion, which is a safe and effective auxiliary method of skin expansion. [ABSTRACT FROM AUTHOR]

This paper presents a novel methodology utilizing physics-informed neural network (PINN) as a junction condition for a 1D network model of blood flow in total cavopulmonary connection generated by the Fontan procedure. The technique integrates a 3D mesh generation process based on the parameterization of the junction geometry, along with a sophisticated physically regularized neural network architecture. Synthetic datasets are produced using 3D steady Stokes simulations within fixed boundaries. We use a physically informed feedforward neural network that utilizes a physically regularized loss function, which incorporates the principle of mass conservation. Our PINN achieves a tolerance of 6% on the test set. We develop a 1D-PINN multiscale model based on a previously developed method for multiscale 1D–3D simulations. Comparison with 1D–3D Stokes based model and 3D Navier–Stokes based model verifies the 1D-PINN model. In the first and second comparison, the maximum deviations of the averaged pressures and flows do not exceed 1.48% and 12.26%, respectively. [ABSTRACT FROM AUTHOR]

The deformability of human red blood cells (RBCs), which comprise almost 99% of the cells in whole blood, is largely related not only to pathophysiological blood flow but also to the levels of intracellular compounds. Therefore, statistical estimates of the deformability of individual RBCs are of paramount importance in the clinical diagnosis of blood diseases. Although the microscale hydrodynamic interactions of individual RBCs lead to non-Newtonian blood rheology, there is no established method to estimate individual RBC deformability from the rheological data of RBC suspensions, and the possibility of this estimation has not been proven. To address this issue, we conducted an integrated analysis of a model of the rheology of RBC suspensions, coupled with macrorheological data of human RBCs suspended in plasma. Assuming a nonlinear curve of the relative viscosity of the suspensions as a function of the cell volume fraction, the statistical average of the membrane shear elasticity was estimated for individual intact RBCs or hardened RBCs. Both estimated values reproduced well the experimentally observed shear-thinning non-Newtonian behavior in these suspensions. We hereby conclude that our complementary approach makes it possible to estimate the statistical average of individual RBC deformability from macrorheological data obtained with usual rheometric tests. [ABSTRACT FROM AUTHOR]

Background: Low-intensity training with blood flow restriction (BFR) training could induce endurance adaptations, its impact on myocardial markers is still unclear compared to training without BFR. Consequently, the influence of low-intensity interval exercise with and without BFR and high-intensity interval exercise (HIIE) on cardiac troponin was determined in this study. Methods: Twelve physically active males between 18 and 26 years volunteered as participants. The participants completed 3 exercise tests in random order, which included 40% VO2max low-intensity cycling without BFR (group L), 40% VO2max low-intensity cycling with BFR set at 60% limb occlusion pressure (LOP) (group B), and 80% VO2max high-intensity cycling without BFR (group H). Participant muscle oxygen, blood flow, oxygen uptake, heart rate (HR), perceived exertion (RPE) rating, and pain levels were determined before and after exercise, after cuff inflation, and pre- and post-each exercise. Moreover, before each protocol, immediately after the exercises, and 3-4 hours after each exercise, elbow vein blood samples were collected to evaluate lactate (LA) and high-sensitivity cardiac troponin T (cTnT). Results: Increased LA was recorded after exercise by the individuals in group H, which was more significant than in group B. Moreover, group B documented a more significant LA increment than group L (P < .05). The peak cTnT of groups B and H after exercise was significantly higher (P < .05). Furthermore, the increase was more significant than the values recorded by group L (P < .05). Conclusion: The present study demonstrated that low-intensity interval exercise combined with BFR could cause cTnT elevations compared to training without BFR. The increase was similar to HIIE protocols. [ABSTRACT FROM AUTHOR]

During acute hypoxic exposure, cerebral blood flow (CBF) increases to compensate for the reduced arterial oxygen content (CaO2). Nevertheless, as exposure extends, both CaO2 and CBF progressively normalize. Haemoconcentration is the primary mechanism underlying the CaO2 restoration and may therefore explain, at least in part, the CBF normalization. Accordingly, we tested the hypothesis that reversing the haemoconcentration associated with extended hypoxic exposure returns CBF towards the values observed in acute hypoxia. Twenty‐three healthy lowlanders (12 females) completed two identical 4‐day sojourns in a hypobaric chamber, one in normoxia (NX) and one in hypobaric hypoxia (HH, 3500 m). CBF was measured by ultrasound after 1, 6, 12, 48 and 96 h and compared between sojourns to assess the time course of changes in CBF. In addition, CBF was measured at the end of the HH sojourn after hypervolaemic haemodilution. Compared with NX, CBF was increased in HH after 1 h (P = 0.001) but similar at all later time points (all P > 0.199). Haemoglobin concentration was higher in HH than NX from 12 h to 96 h (all P < 0.001). While haemodilution reduced haemoglobin concentration from 14.8 ± 1.0 to 13.9 ± 1.2 g·dl−1 (P < 0.001), it did not increase CBF (974 ± 282 to 872 ± 200 ml·min−1; P = 0.135). We thus conclude that, at least at this moderate altitude, haemoconcentration is not the primary mechanism underlying CBF normalization with acclimatization. These data ostensibly reflect the fact that CBF regulation at high altitude is a complex process that integrates physiological variables beyond CaO2. Key points: Acute hypoxia causes an increase in cerebral blood flow (CBF). However, as exposure extends, CBF progressively normalizes.We investigated whether hypoxia‐induced haemoconcentration contributes to the normalization of CBF during extended hypoxia.Following 4 days of hypobaric hypoxic exposure (corresponding to 3500 m altitude), we measured CBF before and after abolishing hypoxia‐induced haemoconcentration by hypervolaemic haemodilution.Contrary to our hypothesis, the haemodilution did not increase CBF in hypoxia.Our findings do not support haemoconcentration as a stimulus for the CBF normalization during extended hypoxia. [ABSTRACT FROM AUTHOR]

The cerebral vasculature manages oxygen delivery by adjusting arterial blood in‐flow in the face of reductions in oxygen availability. Hypoxic cerebral vasodilatation, and the associated hypoxic cerebral blood flow reactivity, involve many vascular, erythrocytic and cerebral tissue mechanisms that mediate elevations in cerebral blood flow via micro‐ and macrovascular dilatation. This contemporary review focuses on in vivo human work – with reference to seminal preclinical work where necessary – on hypoxic cerebrovascular reactivity, particularly where recent advancements have been made. We provide updates with the following information: in humans, hypoxic cerebral vasodilatation is partially mediated via a – likely non‐obligatory – combination of: (1) nitric oxide synthases, (2) deoxygenation‐coupled S‐nitrosothiols, (3) potassium channel‐related vascular smooth muscle hyperpolarization, and (4) prostaglandin mechanisms with some contribution from an interrelationship with reactive oxygen species. And finally, we discuss the fact that, due to the engagement of deoxyhaemoglobin‐related mechanisms, reductions in O2 content via haemoglobin per se seem to account for ∼50% of that seen with hypoxic cerebral vasodilatation during hypoxaemia. We further highlight the issue that methodological impediments challenge the complete elucidation of hypoxic cerebral reactivity mechanisms in vivo in healthy humans. Future research is needed to confirm recent advancements and to reconcile human and animal findings. Further investigations are also required to extend these findings to address questions of sex‐, heredity‐, age‐, and disease‐related differences. The final step is to then ultimately translate understanding of these mechanisms into actionable, targetable pathways for the prevention and treatment of cerebral vascular dysfunction and cerebral hypoxic brain injury. [ABSTRACT FROM AUTHOR]

At least four mechanisms have been proposed to elucidate how neurons in the retrotrapezoid (RTN) region sense changes in CO2/H+ to regulate breathing (i.e., function as respiratory chemosensors). These mechanisms include: (1) intrinsic neuronal sensitivity to H+ mediated by TASK‐2 and GPR4; (2) paracrine activation of RTN neurons by CO2‐responsive astrocytes (via a purinergic mechanism); (3) enhanced excitatory synaptic input or disinhibition; and (4) CO2‐induced vascular contraction. Although blood flow can influence tissue CO2/H+ levels, there is limited understanding of how control of vascular tone in central CO2 chemosensitive regions might contribute to respiratory output. In this review, we focus on recent evidence that CO2/H+‐induced purinergic‐dependent vasoconstriction in the ventral parafacial region near RTN neurons supports respiratory chemoreception. This mechanism appears to be unique to the ventral parafacial region and opposite to other brain regions, including medullary chemosensor regions, where CO2/H+ elicits vasodilatation. We speculate that this mechanism helps to maintain CO2/H+ levels in the vicinity of RTN neurons, thereby maintaining the drive to breathe. Important next steps include determining whether disruption of CO2/H+ vascular reactivity contributes to or can be targeted to improve breathing problems in disease states, such as Parkinson's disease. What is the topic of this review?The homeostatic mechanism that controls breathing in response to changes in CO2/H+ is exquisitely sensitive, with convergent roles proposed for chemosensory brainstem neurons in the retrotrapezoid nucleus (RTN), their supporting glial cells and the vasculature.What advances does it highlight?We focus on recent evidence that CO2/H+‐induced purinergic‐dependent vasoconstriction in the RTN region supports respiratory chemoreception. This mechanism appears to be unique to the RTN and opposite to other medullary chemosensor regions, where CO2/H+ elicits vasodilatation. We speculate that this mechanism helps to maintain CO2/H+ levels in the vicinity of RTN neurons, thereby maintaining the drive to breathe. [ABSTRACT FROM AUTHOR]

This is a summary of a consensus statement on the introduction of "Ultrasound microvasculomics" produced by The Chinese Artificial Intelligence Alliance for Thyroid and Breast Ultrasound. The evaluation of microvessels is a very important part for the assessment of diseases. Super-resolution ultrasound (SRUS) microvascular imaging surpasses traditional ultrasound imaging in the morphological and functional analysis of microcirculation. SRUS microvascular imaging relies on contrast microbubbles to gain sensitivity to microvessels and improves the spatial resolution of ultrasound blood flow imaging for a more detailed depiction of vascular structures and hemodynamics. This method has been applied in preclinical animal models and pilot clinical studies, involving areas including neurology, oncology, nephrology, and cardiology. However, the current quantitative parameters of SRUS images are not enough for precise evaluation of microvessels. Therefore, by employing omics methods, more quantification indicators can be obtained, enabling a more precise and personalized assessment of microvascular status. Ultrasound microvasculomics - a high-throughput extraction of image features from SRUS images - is one novel approach that holds great promise but needs further validation in both bench and clinical settings. Clinical relevance statement: Super-resolution Ultrasound (SRUS) blood flow imaging improves spatial resolution. Ultrasound microvasculomics is possible to acquire high-throughput information of features from SRUS images. It provides more precise and abundant micro-blood flow information in clinical medicine. Key Points: This consensus statement reviews the development and application of super-resolution ultrasound (SRUS). The shortcomings of the current quantification indicators of SRUS and strengths of the omics methodology are addressed. "Ultrasound microvasculomics" is introduced for a high-throughput extraction of image features from SRUS images. [ABSTRACT FROM AUTHOR]

Introduction: Imaging fibroid vascularity may predict fibroid growth and aid to determine most appropriate therapy. Microvascular (MV) flow imaging is relatively new and is able to detect slow flow in small vessels. Data on feasibility, reproducibility, and reliability of MV‐flow imaging in fibroids is lacking. The purpose of our study was to determine the reproducibility of MV‐flow imaging and to explore this technique for clinical practice for assessing blood flow in fibroids. Material and Methods: Thirty patients with one or multiple fibroids (diameter 1.5–12.0 cm) were prospectively included. Transvaginal ultrasound scanning was performed in B‐mode, 2D MV‐Flow™, 2D and 3D power Doppler mode (HERA W10, Samsung) by two experienced gynecologists at a tertiary care clinic from February to December 2021. The primary outcome was intra‐ and interobserver agreement of the vascular index (VI) and color score (CS). The following parameters: '2D MV‐flow VI', '3DPD VI', '2D MV‐flow CS' and '2DPD CS' were measured offline in the center, pseudocapsule, and entire fibroid. Secondary offline outcomes for exploring 2D MV‐flow for clinical practice, included (1) ability to discern vascular structures, (2) assessing the degree of vascularity via CS and calculating a VI, and (3) determining penetration depth of the ultrasound signal in both power Doppler and MV‐flow imaging. Results: All scans of the 30 included patients were of sufficient quality to analyze. Inter‐ and intra‐observer correlations of all studied parameters were good to excellent, both for 2D MV‐flow and 2D power Doppler (intercorrelation coefficient 0.992–0.996). Using 2D MV‐flow different vascular structures were visible in detail, in contrary to using 2D and 3D power Doppler. In significantly more fibroids central flow could be visualized using 2D MV‐flow (63%) than with 2D power Doppler (13%, p = 0.001). Finally, penetration of the ultrasound signal was deeper using 2D MV‐flow (3.92 cm) than with 2D power Doppler (2.95 cm, p = 0.001). Conclusions: Using 2D MV‐flow imaging for determining vascularity is highly reproducible. It has potential added value for clinical practice as it depicts detailed vascular structures and the degree of vascularity, especially in the center of the fibroid. [ABSTRACT FROM AUTHOR]

To characterize the correlation, agreement and concordance of cardiac output (CO) measured with transthoracic ultrasound and the correlation and concordance of aortic blood flow (ABF) minute distance (MD) measured by transesophageal Doppler with CO measured by pulmonary artery thermodilution (PATD) in cats. Experimental study. A group of six healthy male neutered cats, aged 2–8 years and weighing 5.3 ± 0.3 kg. Cats were anesthetized with isoflurane in oxygen. CO was measured by PATD (CO PATD) and transthoracic echocardiography (CO ECHO). ABF MD was measured using an esophageal Doppler flow probe aligned with descending ABF. All measurements were made under three conditions: dexmedetomidine (20 μg kg–1) intravenously; atipamezole (200 μg kg–1) intramuscularly and atropine (20 μg kg–1) intravenously as needed to achieve a minimum heart rate of 140 beats minute–1; and dopamine (20 μg kg–1 minute–1) intravenously in that order. Correlation between CO PATD and CO ECHO , and CO PATD and Doppler MD was evaluated using repeated measures correlation. Agreement between CO PATD and CO ECHO was evaluated using Bland–Altman method. Differences between consecutive pairs of CO measurements were calculated for concordance analysis. Correlation between CO PATD and CO ECHO and between CO PATD and MD was significant (p < 0.001), with correlation coefficients greater than 0.92. A bias of > 27% and upper limits of agreement of 66% were found between CO PATD and CO ECHO. Concordance rate with CO PATD was 76–80% for CO ECHO and 72% for MD. Echocardiographic methods for the measurement of CO showed poor agreement and concordance with PATD. MD showed poor concordance with PATD. As such, these methods cannot be used as an alternative to PATD nor can they appropriately track changes in CO in anesthetized cats. [ABSTRACT FROM AUTHOR]

Objectives: Detection of synovitis is essential for assessing the activity and predicting the prognosis of rheumatoid arthritis (RA). The aim of this study was to investigate the diagnostic performance of superb microvascular imaging (SMI) in RA patients with high, moderate, and low activity. Methods: One hundred four patients with active RA were selected from the hospital between May 2022 and August 2023. The study observed the correlation between bone erosion of the carpal joint, joint cavity effusion, thickness of synovial hyperplasia of the carpal joint, positivity rate of synovial blood vessels, and their semiquantitative scores with the clinical disease activity of RA using SMI examination. Results: The detection of synovial hyperplasia thickness and joint effusion in the high-activity group was higher than that in the low-activity group, and the difference was statistically significant (P < 0.05). The quantitative SMI test demonstrated that the synovial blood flow grading and semiquantitative grade increased gradually with activity level (P<0.05). During the high, moderate, and low-activity groups, the vascular index (VI) value of the hyperplastic synovial membrane decreased gradually, showing statistical significance both between and within the groups (P<0.05). Conclusion: SMI technology exhibited high sensitivity and accuracy in assessing disease activity in RA. It holds significant clinical application value as a reliable auxiliary tool for assessing disease activity in RA and treatment. Key Points • Super micro-vascular imaging (SMI) demonstrated higher detection rates of microvessels in RA patients with high disease activity compared to those with low activity, showing statistical significance. • The quantitative SMI test revealed a clear correlation between synovial blood flow grading and disease activity levels in RA patients, highlighting the potential of SMI as a valuable tool for disease activity and treatment of rheumatoid arthritis. [ABSTRACT FROM AUTHOR]

Purpose: Fasciotomy is a surgical procedure that involves the incision of fascial compartments in the body to relieve pressure, prevent tissue damage, and maintain blood flow. This study aimed to investigate the effectiveness of the Bogota Bag technique in closing fasciotomy wounds in patients with lower limb compartment syndrome. Methods: A prospective cohort study was conducted between October 2022 and October 2023 to document our experience in employing the Bogota Bag technique for fasciotomy closure. The study included the evaluation of medical files from fifteen patients aged 17 to 61. Results: The outcomes of the study present the initial series of limb fasciotomies treated with the Bogota Bag technique. Fifteen patients (14 male, 1 female) were included in the study. The average age of the patients was 34.73 ± 13.9 years and the average hospitalization was 8.33 ± 3.2 days. The average closure time of fasciotomy is 3.6 ± 1.4 days. Conclusion: This report makes a significant contribution as the first documented series of limb fasciotomies treated with the Bogota Bag technique. This method exhibits simplicity in execution, cost-effectiveness, and a low incidence of complications. [ABSTRACT FROM AUTHOR]

• Biopsy for asymptomatic postmenopausal women if endometrial thickness is ≥8 mm. • For 4-8 mm, consider biopsy after evaluating risk factors and blood flow signals. To determine the cutoff value for endometrial thickness (ET) that prompts a biopsy in asymptomatic postmenopausal women with an incidental finding of thickened endometrium, and to develop a risk prediction model. This is a retrospective cohort analysis of the clinical records of the Hysteroscopic Center of Fu Xing Hospital, Capital Medical University, Beijing, China. We collected asymptomatic postmenopausal women who presented with an ET of ≥4 mm (double-layer) as an incidental finding. We stratified the participants into non-malignant and malignant groups based on pathology results and assessed differences between the two groups. A receiver operating characteristic curve (ROC) was used to identify the cutoff value of ET for predicting endometrial malignancy. Logistic regression models were also constructed to predict the risk of malignancy. A total of 581 consecutive eligible cases were included. The optimal cutoff value for ET was 8 mm, with a maximum area under the curve (AUC) of 0.755 (95 % CI: 0.645–0.865). In addition to ET, the regression model incorporated diabetes, blood flow signal, BMI, and hypertension to predict the risk of malignancy. A ROC curve constructed for the model yielded an AUC of 0.834 (95 % CI: 0.744–0.924). It is reasonable to offer hysteroscopy and visually-directed endometrial biopsy for asymptomatic postmenopausal women when ET is 8 mm or above. For those with an ET between 4 and 8 mm, further decision to perform biopsy should be determined on an individual basis, considering risk factors and blood flow signals of the endometrium. [ABSTRACT FROM AUTHOR]

This paper explores the impact of temperature on the fractionalization of magnetic nanoparticles in blood, coupled with vibratory motion influenced by rotation. The distribution systems exhibit heightened diffusivity, explored numerically through the finite difference method and the L1 ${L}_{1}$ algorithm. The temperature distribution robustly responds to elevated fractional parameters, indicating a critical threshold. The study achieves a comprehensive understanding of temperature and velocity evolution in different tube zones. In comparison, single‐walled carbon nanotubes surpass multiple‐walled carbon nanotubes in distributions, while CuO nanoparticles demonstrate larger distributions at an average fractional‐order parameter of α=0.5 $\alpha =0.5$. In the observed growth region at α=0.73,Fe2O3 $\alpha =0.73,{\text{Fe}}_{2}{{\rm{O}}}_{3}$ and TiO2 ${\text{TiO}}_{2}$ exhibit noteworthy temperature distributions, highlighting the fractional derivative's impact in highly diffusive models with nanoparticles. It is also noted that in this region, the temperature distribution tends to decrease for all the parameters and values examined, particularly at a low Reynolds number (Re=0.5 ${R}_{e}=0.5$). However, the introduction of nanoparticles accelerates the processes and distributions across the various observed zones. Furthermore, the accelerated behavior of each nanoparticle can be moderated based on its sphericity. By encompassing all facets of fractional order for controlled rotations, the study sheds light on the role of magnetized nanoparticles in blood dynamics, emphasizing the significance of a critical zone where certain physicochemical properties are disrupted, potentially leading to cellular disorders, and the fluidodynamic effects of vortex flow. This perspective is pivotal for addressing tissue lesions induced by vibrations, as seen in the case of coagulations, and for targeting carcinogenic areas using nanoelements. [ABSTRACT FROM AUTHOR]

There is no study that has investigated the impact of exercise in a combined hypoxic and hot environment on endothelial function. Therefore, we tested whether aerobic exercise in a combined hypoxic and hot conditions induces further enhancement of endothelial function. Twelve healthy males cycled at a constant workload (50% of their maximal oxygen uptake under normoxic/thermoneutral conditions) for 30 min in four different environments: exercise under normoxic condition (NOR: fraction of inspiratory oxygen or FiO2 = 20.9%, 20°C), exercise under hypoxic condition (HYP: FiO2 = 14.5%, 20°C), exercise under hot condition (HOT: FiO2 = 20.9%, 30°C), and exercise under combined hypoxia and hot conditions (HH: FiO2 = 14.5%, 30°C). Before, during, and after exercise, cardiovascular variables (e.g., heart rate, blood flow, and shear rate), blood variables, and endothelial function evaluated by flow‐mediated dilation (FMD) were assessed. Heart rates were significantly higher throughout the HH trial's experimental period than the other trials (p < 0.05). However, in the HH trial, brachial artery blood flow and shear rate did not differ from those in other trials after exercise. Plasma catecholamines (epinephrine, norepinephrine, and dopamine) elevations in response to exercise were significantly higher in the HH trial than in the other three trials (p < 0.05). No considerable differences were observed in FMD responses among trials before and after the exercise. In conclusion, aerobic exercise in a combined hot and hypoxic environment further activated sympathetic nervous activity but did not considerably enhance blood flow, shear rate, or endothelial function. [ABSTRACT FROM AUTHOR]

Background: Endometriosis, due to its ambiguous symptoms, still remains one of the most difficult female diseases to treat, with an average diagnosis time of 7–9 years. The changing level of hypoxia plays an important role in a healthy endometrium during menstruation and an elevated expression of the hypoxia-inducible factor 1-alpha (HIF-1α) has been demonstrated in ectopic endometria. HIF-1α mediates the induction of proangiogenic factors and the development of angiogenesis is a critical step in the establishment and pathogenesis of endometriosis. Although the inhibition of angiogenesis has been proposed as one of the actionable therapeutic modalities, vascular normalization and re-oxygenation may become a possible new approach for therapeutic intervention. Methods: Our goal was to investigate whether a selected murine model of endometriosis would be suitable for future studies on new methods for treating endometriosis. Non-invasive, high-resolution ultrasound-monitored observation was selected as the preclinical approach to obtain imaging of the presence and volume of the endometriotic-like lesions. The EF5 (2-(2-Nitro-1H-imidazol-1-yl)-N-(2,2,3,3,3-pentafluoropropyl)acetamide) compound that selectively binds to reduced proteins in hypoxic cells was used for hypoxia detection. The expression of Pten and other crucial genes linking endometriosis and hypoxia were also assessed. Results: Using EF5, a pentafluorinated derivative of the 2-nitroimidazole that is metabolically reduced by oxygen-inhibitable nitroreductase, we confirmed that hypoxia did develop in the selected model and was detected in uterine and ectopic endometriotic lesions. Moreover, the changes in oxygen tension also influenced the expression level of significant genes related to endometriosis, like Pten, Trp53, Hif1a, Epas1, and Vegfa. Their strong modulation evidenced here is indicative of model reliability. Using high-resolution ultrasound-based imaging, we present a non-invasive method of visualization that enables the detection and observation of lesion evolution throughout the duration of the experiment, which is fundamental for further preclinical studies and treatment evaluation. Conclusions: The selected model and method of visualization appear to be suitable for the study of new treatment strategies based on hypoxia alleviation and blood flow restoration. [ABSTRACT FROM AUTHOR]

Objective Methods Results Conclusion This study evaluates the endometrial receptivity of obstetric anticardiolipin syndrome (OAPS) patients using various ultrasound indicators and the efficacy of low‐dose aspirin (LDA) treatment.This retrospective study recruited patients from Shanghai Ren Ji Hospital, China from January 2022 to December 2023. Doppler parameters of the endometrium and uterine artery blood flow were recorded to assess the endometrial receptivity of OAPS patients compared with normal pregnant women and an other immune diseases group. The receiver operating characteristic curve was used to predict the risk of OAPS patients. Doppler parameters of OAPS patients were conducted repeatedly after a 2‐month period of treatment with LDA.Compared with normal pregnant women, the OAPS group showed remarkably increased endometrial perfusion resistance (PI, RI, S/D) and uterine artery perfusion resistance (RI and S/D) (P < 0.001) and had good predictive values (area under the curve = 0.806, 0.976, 0.942, 0.902, and 0.901, respectively). The endometrial thickness of the OAPS group was much thinner than that of the normal group (P < 0.001). Uterine blood flow impedance PI showed no difference in both groups (P = 0.68). In comparison to other autoimmune diseases, the OAPS group also showed an increasing trend in the resistance of endometrium and uterine artery blood flow. After LDA treatment, there was an obvious improvement in the endometrial blood flow perfusion in the OAPS group (P < 0.01).Compared with the normal group and other autoimmune diseases, the resistance of endometrial and uterine artery blood flow in the OAPS group was increased significantly. The Doppler index showed the predictive value of OAPS, and it was confirmed that LDA could enhance blood perfusion among OAPS women. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive hemodynamic evaluation of two endovascular techniques for treating cerebral aneurysms. Using the finite volume method, we simulated pulsatile blood flow and heat transport dynamics in two saccular aneurysms of varying sizes and shapes. We assessed hemodynamic factors under two coiling conditions with different porosities and deformation stages to identify the most effective treatment for each case. Our computational analysis reveals that stent and coiling applications are more efficient for aneurysms with low-sac volume. Notably, stent placement proves to be more effective than coiling in treating saccular aneurysms. Our findings indicate that stent-induced deformation sufficiently diverts the main blood flow, thereby reducing the risk of aneurysm rupture near the ostium region. [ABSTRACT FROM AUTHOR]

This paper focuses on the study of activation energy and entropy generation in the peristaltic flow of a Carreau–Yasuda nanofluid. Peristaltic transport, coupled with entropy generation and activation energy in a curved geometry, has significant applications in biomedical and industrial processes involving non‐Newtonian fluids. Blood flow in the arteries, the movement of chyme in the gastrointestinal tract, and peristaltic motion replicate the natural muscular contractions that drive fluid flow in the physiological systems. The integration of entropy generation allows for the evaluation of energy efficiency and the analysis of losses due to viscous dissipation. Activation energy plays a crucial role in processes such as drug delivery, where temperature‐sensitive reactions or biochemical changes affect fluid behavior. In industrial applications, like peristaltic pumps in chemical reactors or polymer processing, the consideration of entropy and activation energy aids in optimizing thermal management and reaction rates. The mathematical model is developed under these assumptions, and the governing equations are numerically solved using the NDSolve function in Mathematica. Graphical results show that higher activation energy and concentration reduce the reaction rate, while the Bejan number and entropy generation increase with a larger Brinkman number. Velocity and temperature increase under slip conditions, whereas concentration decreases, and a stronger radial magnetic field reduces both velocity and the size of the trapped bolus. [ABSTRACT FROM AUTHOR]

Ciliary‐driven flows manifest prominently in various physiological and biological phenomena, serving as micro mixers in cilia‐based actuators, regulating flow in small biosensors, and functioning as micro pumps in drug‐delivery systems. Although there are some studies on cilia driven flows, however, electroosmotic flow of Williamson nanofluid in a non‐uniform ciliated channel has not been reported before. Keeping in view, the present study aims to investigate electroosmotic transport of blood through a non‐uniform wavy ciliated channel. The Williamson fluid model is employed to investigate the properties of blood. Graphene oxide nanoparticles are inserted within blood to examine the flow and thermal characteristics. Moreover, streamline patterns, average pressure rise, and temperature contours are also portrayed against sundry physical parameters to present a detailed physical analysis. The obtained results revealed that concentration profile declines with Eckert number Ec,$Ec,$ Soret number Sr$Sr$, Weissenberg number We,$We,$ and nanoparticle volume fraction ϕ$\phi $ while it enhances with Grashof number Gr$Gr$. Temperature of the fluid significantly drops by enhancing Grashof number Gr$Gr$ and volume flow rate Q,$Q,$ while it rises with Eckert number Ec,$Ec,$ Weissenberg number We,$We,$ and nanoparticle volume fraction ϕ$\phi $. The average pressure rise per unit wavelength escalates with a rise in the volume fraction of nanoparticles (ϕ) in the peristaltic pumping region. However, beyond a critical value, it diminishes in the free and augmented pumping regions. Streamline patterns indicates a shrinking in the size of trapping bolus by enhancing the volume flow rate Q.$Q.$ Temperature contours are significantly influenced by enhancing the Eckert number Ec$Ec$. [ABSTRACT FROM AUTHOR]

Optoacoustic imaging offers label‐free multi‐parametric characterization of cerebrovascular morphology and hemodynamics at depths and spatiotemporal resolution unattainable with optical microscopy. Effective imaging depth can greatly be enhanced by employing photons in the second near‐infrared (NIR‐II) window. However, diminished absorption by hemoglobin along with a lack of suitable contrast agents hinder an efficient application of the technique in this spectral range. Herein, copper sulfide (CuS) micro‐ and nano‐formulations for multi‐scale optoacoustic imaging in the NIR‐II window are introduced. Dynamic contrast enhancement induced by intravenously administered CuS nanoparticles facilitated visualization of blood perfusion in murine cerebrovascular networks. The individual calcium carbonate microparticles carrying CuS are further shown to generate sufficient responses to enable super‐resolution microvascular imaging and blood flow velocity mapping with localization optoacoustic tomography. [ABSTRACT FROM AUTHOR]

Background and Purpose Experimental Approach Key Results Conclusion and Implications Salvianolic acid B (SalB) demonstrates diverse clinical applications, particularly in cardiovascular and cerebral protection. This study primarily investigated the effects of SalB on sepsis.The model of sepsis via caecal ligation puncture (CLP) was established in male C57BL/6 mice. Therapeutic effects of SalB on hepatic and pulmonary injury, inflammatory responses and microcirculatory disturbances in sepsis were evaluated. Platelet aggregation and adhesion were measured via flow cytometry and an adhesion test. After overexpression of platelet‐related activating molecules by 293T cells, the efficient binding of SalB and platelet CD226 molecules was further evaluated. Finally, neutralizing antibody experiments were used to assess the mechanism of SalB in alleviating the progression of sepsis.SalB mitigated hepatic and pulmonary impairments, reduced inflammatory cytokine levels and enhanced mesenteric microvascular blood flow in septic mice. SalB enhanced CLP‐induced reduction of platelet count and platelet pressure cumulative volume. SalB reduced platelet adhesion to endothelial cells and platelet aggregation to leukocytes. A high binding efficiency was observed between SalB and the platelet adhesion molecule CD226. Ex vivo, interactions between SalB and platelets from CD226‐knockout mice were markedly decreased. In vivo administration of CD226 neutralizing antibodies significantly delayed disease progression and enhanced mesenteric microcirculation in septic mice.In our murine model of sepsis, treatment with SalB improved the microcirculatory disturbance and hindered the progression of sepsis by inhibiting platelet CD226 function. Our results suggest SalB is a promising therapeutic approach to the treatment of sepsis. [ABSTRACT FROM AUTHOR]

ABSTRACT Background Methods Results Conclusion Cuff extrusion of tunneled dialysis catheter (TDC) leads to catheter dysfunction, leading to loss of vascular access and the need for new catheter. Definitive management is to remove TDC and reinsert new catheter by new venous puncture and tunnel, which may not be possible in all cases. The study evaluated the surgical experience and early outcomes of a novel “Catheter Exchange with Elongation of Tunnel (CEET)” procedure for cuff extrusion.The retrospective study included all cases of hemodialysis with TDC with partial or complete cuff extrusion and excluded complete catheter dislodgement, tunnel infection, or any catheter related infection. All patients also underwent the CEET procedure under fluoroscopy guidance, and the clinical details and outcomes were analyzed.Eleven cases of TDC cuff extrusion underwent the CEET procedure of which three (27.2%) had previous and four (36.4%) had partial cuff extrusion, and seven cases (63.6%) had short tunnel length, which likely predisposed to cuff extrusion. CEET procedure was successful in 10 cases (success rate 90.1%) with desired position of catheter tip and good blood flow. Study population was divided into early and late cuff extrusion (≥1 month). Short tunnel length was associated with late extrusion (p = 0.05), whereas premature removal of TDC anchor sutures was associated with early cuff extrusion (p = 0.04).CEET procedure is a successful alternative technique for correction of cuff extrusion of TDC with good success rate. Premature removal of anchor sutures was associated with early cuff extrusion, whereas short tunnel length was associated with late cuff extrusion. [ABSTRACT FROM AUTHOR]

Point-of-care (POC) platelet function analysis can enable timely and precise management of bleeding and clotting in emergency rooms, operation rooms and intensive care units. However, POC platelet testing is currently not commonly performed, due to the complexity of sample preparation and limitations of existing technologies. Here, we report the development of an integrated microfluidic multiple electrode aggregometry (μMEA) sensor which uses multi-frequency impedance measurement of an embedded microelectrode array to perform platelet aggregometry directly from whole blood, sensing and measuring platelet activation in a label-free manner and without requiring any additional sample preparation. Additionally, the sensor incorporates blood flow during the assay to account for physiological flow and shear conditions. We show that the impedance signal from the sensor can be used to accurately detect and quantify platelet aggregation in a label-free manner, which was further validated by simultaneous fluorometric measurement and visualization of platelet aggregation. Further, we optimized the sensitivity and repeatability of the sensor using its frequency response and demonstrated that the sensor could be used to characterize drug dose–response in antiplatelet therapy with a frequency-tunable dynamic range. We also demonstrate that the sensor provides high sensitivity to perform platelet aggregometry under thrombocytopenic or low platelet count conditions. The μMEA sensor could thus enable POC platelet function analysis across several clinical applications. [ABSTRACT FROM AUTHOR]

Objective Methods Results Conclusion To detect an abnormal intra‐amniotic structure around the internal cervical os using transvaginal sonography at 18–21+6 weeks of gestation.In this cohort study, during a 12‐month period from July 2022 to June 2023, 395 transvaginal scans were performed for second‐trimester cervical‐length screening in singleton pregnancies at 18–21+6 weeks of gestation. Nine abnormal intra‐amniotic structures (AIAS), 87 low‐lying placentas (LLP, second‐trimester placenta previa or placental margin within 2 cm from internal cervical os), and 299 controls (not LLP and no abnormal finding around internal cervical os) were diagnosed. Sonographic features of AIAS and delivery outcomes in the three groups were compared.Sonographic features of nine AIAS cases were: two single bands, one single broad band, one multiple bands, one single tubular, and one multiple tubulars. Blood flow was noted in seven cases. Seven AIAS had disappeared by 26 weeks, one was resolved at 34 weeks, and one (vasa previa and parachute placenta) remained until delivery. Incidences of emergency cesarean section, abnormal placenta and umbilical cord, and abnormal deliveries in AIAS were significantly higher than those in LLP and control groups (P = 0.031). Blood losses during delivery in AIAS and LLP groups were significantly greater than in the control group (P = 0.004), but there was no significant difference in blood loss between AIAS and LLP groups.The incidence of AIAS around the internal cervical os in the second trimester was 2.28% (9/395 fetuses). Mid‐second‐trimester transvaginal sonographic screening for the detection of AIAS around the internal cervical os including vasa previa may be essential to reduce perinatal morbidity. [ABSTRACT FROM AUTHOR]