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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]

Despite the known interplay between blood flow and function, to our knowledge, there is currently no minimally invasive method to monitor diaphragm hemodynamics. We used contrast-enhanced ultrasound to quantify relative diaphragm blood flow (Q ˙ DIA) in humans and assessed the technique's efficacy and reliability during graded inspiratory pressure threshold loading. We hypothesized that: (1) Q ˙ DIA would linearly increase with pressure generation, and (2) that there would be good test-retest reliability and interanalyzer reproducibility. Can we validate what is, to our knowledge, the first minimally invasive method to measure relative diaphragm blood flow in humans? Quantitative contrast-enhanced ultrasound of the costal diaphragm was performed in healthy participants (10 male participants, 6 female participants; mean age 28 ± 5 years; BMI 22.8 ± 2.0 kg/m) during unloaded breathing and three stages of loaded breathing on two separate days. Gastric and esophageal balloon catheters measured transdiaphragmatic pressure. Ultrasonography was performed during a constant-rate IV infusion of lipid-stabilized microbubbles following each stage. Ultrasound images were acquired after a destruction-replenishment sequence and diaphragm specific time-intensity data were used to determine Q ˙ DIA by two individuals. Transdiaphragmatic pressure for unloaded and each loading stage were 15.2 ± 0.8, 26.1 ± 0.8, 34.6 ± 0.8, and 40.0 ± 0.8 percentage of the maximum, respectively. Q ˙ DIA increased with each stage of loading (3.1 ± 3.1, 6.9 ± 3.6, 11.0 ± 4.9, and 13.5 ± 5.4 acoustic units/s; P <.0001). The linear relationship between diaphragmatic flow and pressure was reproducible from day to day. Q ˙ DIA had good to excellent test-retest reliability (0.86 [0.77, 0.92]; P <.0001) and excellent interanalyzer reproducibility (0.93 [0.90, 0.95]; P <.0001) with minimal bias. Relative Q ˙ DIA measurements had valid physiological underpinnings, were reliable day-to-day, and were reproducible analyzer-to-analyzer. This study indicated that contrast-enhanced ultrasound is a viable, minimally invasive method for assessing costal Q ˙ DIA in humans and may provide a tool to monitor diaphragm hemodynamics in clinical settings. [Display omitted] [ABSTRACT FROM AUTHOR]

The brachiopods are sessile invertebrates with an unusual blood system, which consists of a long‐branched dorsal vessel. It is still unknown how blood circulates in this system. In the present study, for the first time we propose the circulation of blood in brachiopod Hemithiris psittacea based on morphological and experimental data. The main heart is located on the dorsal side of the stomach and divides the dorsal vessel into anterior and posterior parts. The anterior part enters the lophophore, where it gives off blind branches to each tentacle. The posterior part passes by the funnels of the nephridia and forms a blindly closed network in the gonads. We suggest that the circulation of blood includes three successive stages. During the first phase of systole of the main heart, blood flows through the anterior dorsal vessel. During the second phase of systole, blood flows through the posterior dorsal vessel. During diastole, blood flows from the anterior and posterior vessels and fills the main heart. The origin of a peculiar blood system in brachiopods can be explained by reduction of the ventral vessel, which is probably correlates with the reduction of the ventral side of the brachiopod ancestor's body. Another peculiarity of brachiopod blood system is the presence of an ampullar heart, which functions as a blood depot and allows blood to move in the vessels in two directions in an oscillatory mode. The brachiopod blood system contains vessels lacking true endothelium and can be classified as an "incompletely closed" type. Research Highlights: The blood system of brachiopods contains a dorsal vessel divided into anterior and posterior parts. Circulation includes three stages: during the first phase of systole, blood flows in the anterior vessel, during the second phase of systole, blood flows in the posterior vessel, and during diastole, blood flows from the anterior and posterior vessels and fills the main heart. [ABSTRACT FROM AUTHOR]

Background: In microvascular head and neck reconstruction, ischemia of the free flap tissue is inevitable during microsurgical anastomosis and may affect microvascular free flap perfusion, which is a prerequisite for flap viability and a parameter commonly used for flap monitoring. The aim of this study was to investigate the influence of the number of ischemia intervals and ischemia duration on flap perfusion. Methods: Intraoperative and postoperative flap blood flow, hemoglobin concentration, and hemoglobin oxygen saturation at 2 and 8 mm tissue depths, as measured with the O2C tissue oxygen analysis system, were retrospectively analyzed for 330 patients who underwent microvascular head and neck reconstruction between 2011 and 2020. Perfusion values were compared between patients without (control patients) and with a second ischemia interval (early or late) and examined with regard to ischemia duration. Results: Intraoperative and postoperative flap blood flow at 8 mm tissue depth were lower in patients with early second ischemia intervals than in control patients [102.0 arbitrary units (AU) vs 122.0 AU, P =.030; 107.0 AU vs 128.0 AU, P =.023]. Both differences persisted in multivariable analysis. Intraoperative and postoperative flap blood flow at 8 mm tissue depth correlated weakly negatively with ischemia duration in control patients (r = −.145, P =.020; r = −.124, P =.048). Both associations did not persist in multivariable analysis. Conclusions: The observed decrease in microvascular flap blood flow after early second ischemia intervals may reflect ischemia-related vascular flap tissue damage and should be considered as a confounding variable in flap perfusion monitoring. [ABSTRACT FROM AUTHOR]

Optofluidic regulation of blood microflow in vivo represents a significant method for investigating illnesses linked to abnormal changes in blood circulation. Currently, non-invasive strategies are limited to regulation within capillaries of approximately 10 μm in diameter because the adaption to blood pressure levels in the order of several hundred pascals poses a significant challenge in larger microvessels. In this study, using laser-induced microbubble formation within microvessels of the mouse auricle, we regulate blood microflow in small vessels with diameters in the tens of micrometers. By controlling the laser power, we can control the growth and stability of microbubbles in vivo. This controlled approach enables the achievement of prolonged ischemia and subsequent reperfusion of blood flow, and it can also regulate the microbubbles to function as micro-pumps for reverse blood pumping. Furthermore, by controlling the microbubble, narrow microflow channels can be formed between the microbubbles and microvessels for assessing the apparent viscosity of leukocytes, which is 76.9 ± 11.8 Pa·s in the in vivo blood environment. The proposed design of in vivo microbubble valves opens new avenues for constructing real-time blood regulation and exploring cellular mechanics within living organisms. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effects of local calf vibration on balance, blood flow, and nerve conductivity in patients with diabetic peripheral neuropathy (DPN). An open-label controlled trial was designed. Patients with confirmed diagnoses of type 2 diabetes and DPN were enrolled in the study and underwent ten sessions of local calf vibration therapy for the dominant leg. The other leg was considered the control. Balance evaluation, nerve conduction studies, and color Doppler ultrasound were performed before and after the treatment course. The Wilcoxon signed rank test and the Mann–Whitney test were used to evaluate the differences between the test results before and after the intervention and between the intervention and control legs. Seventeen patients with a mean age of 60.3 ± 5.6 years (11 males) participated in the study. Mean Brief BESTest total scores were significantly improved (14.06 vs. 17.35; P =.01, Cohen's d = 0.743). There were no significant differences between the treated and control legs regarding the nerve conduction and color Doppler ultrasound parameters before and after the intervention (P ≥.054). Changes in the parameters were also not significantly different between legs (P ≥.078), except for common peroneal nerve conduction velocity, for which there was a higher increase in its value in the treated legs compared to the control legs (4.17 vs. 0.9, P =.002). Local calf vibration may positively affect balance and lower extremities nerve conduction in patients with DPN, and the findings of this study can be a basis for studies evaluating the efficacy of local calf vibration for treating DPN. [ABSTRACT FROM AUTHOR]

This study sought to evaluate the effects of oral contraceptive (OC) and hormonal intrauterine device (H-IUD) use, compared with a eumenorrheic (EUM) cycle, on fatigability and recovery between hormone the phases. Peak power (PP), average power (AP), fatigue index (FI), blood lactate, vessel diameter, and blood flow (BF) were measured from a repeated sprint cycle test (10 × 6 seconds) in 60, healthy, active women (mean ± SD; age: 26.5 ± 7.0 years, BMI: 22.5 ± 3.7 kg-m-2) who used monophasic OC (≥6 months; n = 21), had a H-IUD (≥6 months; n = 20), or had regular naturally occurring menstrual cycle (≥3 months) or had a nonhormonal IUD (EUM; n = 19). Subjects were randomly assigned to begin in either the low-hormone phase (LHP) or high-hormone phase (HHP) and were tested once in each phase. Separate univariate analyses of covariances assessed the change from HHP to LHP between the groups, covaried for progesterone, with significance set at p≤ 0.05. All groups demonstrated similar changes in PP, AP, FI, blood lactate, vessel diameter, and BF between the phases (p > 0.05). Although not significant, AP was higher in LHP for OC (A-248.2 ± 1,301.4 W) and EUM (A-19.5 ± 977.7 W) and higher in HHP for H-IUD (A 369.3 ± 1,123.0 W). Oral contraceptive group exhibited a higher FI (A 2.0%) and reduced blood lactate clearance (A 2.5%) in HHP. In recreationally active women, hormonal contraception and hormone phases may minimally impact fatigue and recovery. Individual elite female athletes may benefit from understanding hormonal contraception type as performance and recovery may slightly vary across the cycle. [ABSTRACT FROM AUTHOR]

Background/Aims: The growing prevalence of sedentary behaviour across the life course is linked to an increased risk of chronic venous disease and related mortality, warranting the need for non-invasive interventions to improve blood flow and lower extremity function. The aim of this study was to investigate the change in venous blood flow, heart rate and blood pressure after 8 minutes of using the Leeper device, Circulation Booster and light intensity walking. Methods: A quasi-experimental crossover study involving 11 participants (eight women, three men, mean age 23.91 years, standard deviation 1.04 years) was conducted using Leeper and Circulation Booster devices and light intensity walking. During each intervention, participants exercised for 8 minutes, and blood flow was recorded at 0, 4 and 8 minutes. Heart rate and blood pressure were recorded at 0 and 8 minutes. Blood flow was the primary outcome measure, and heart rate and blood pressure were secondary outcomes. Participants rested for 10 minutes between exercise. A two-way repeated measures analysis of variance was used to analyse the effect of intervention and time on blood flow, blood pressure and heart rate. Results: There was no significant interaction between intervention and time on blood flow (P=0.180) indicating that blood flow did not change over time depending on intervention. There was no significant main effect of time on blood flow (P=0.206), indicating that no intervention caused a significant increase or decrease in blood flow after 8 minutes of exercise. Conclusions: The interventions involving the Leeper and Circulation Booster devices and light intensity walking did not appear to significantly increase blood flow in young adults. Further studies involving participants from older age groups and those with pathological interventions are warranted to examine the potential effectiveness of these interventions. Implications for practice: The findings may assist with the advice that allied health professionals provide regarding the use of seated exercise trainers and EMS devices and their ability to influence changes in blood flow. [ABSTRACT FROM AUTHOR]

The article focuses on a research which examines the exercise blood flow regulation in heart failure with preserved ejection fraction (HFpEF). Findings of the study demonstrated that alpha adrenergic restraint is a potential mechanism limiting Vo2, a key functional outcome in adults with HFpEF. The findings also highlight new potential mechanisms leading to exercise intolerance in adults with HFpEF.

XRD diffraction and IR absorption were investigated for raw loess powder and heat-treated loess powder. Raw loess retains its useful minerals, but loses their beneficial properties when calcined at 850 °C and 1050 °C. To utilize the useful minerals, loess balls were made using a low-temperature wet-drying method. The radiant energy and transmittance were measured for the loess balls. Far-infrared ray (FIR) emitted from loess bio-balls is selectively absorbed as higher vibrational energy by water molecules. FIR can raise the body's core temperature, thereby improving blood flow through the body's thermoregulatory mechanism. In an exploratory study with 40 participants, when the set temperature of the loess ball mat was increased from 25 °C to 50 °C, blood flow increased by 39.01%, from 37.48 mL/min to 52.11 mL/min, in the left middle finger; in addition, it increased by 39.62%, from 37.15 mL/min to 51.87 mL/min, in the right middle finger. The FIR emitted from loess balls can be widely applied, in various forms, to diseases related to blood flow, such as cold hands and feet, diabetic foot, muscle pain, and menstrual pain. [ABSTRACT FROM AUTHOR]

Siphons are devices that transport liquids uphill between two containers. It has been proposed that a siphon principle operates in closed circulatory systems, as best exemplified by the circulation of blood in mammals. This principle is supposed to ensure that no additional work is necessary to pump blood above the level of the heart, and that there is no gravitational static pressure gradient in the column of blood. The first statement is correct, while we demonstrate that, ignoring hydraulic resistance to blood flow, the static pressure gradient is equal to the hydrostatic gradient in a siphon model of blood circulation, although the details of the proof do not depend on the geometry of the circulatory system and the proof can be trivially extended to other models such as a vascular waterfall. This implies that the controversy over the siphon principle has no implications for the description of blood circulation, and that mechanisms such as the "baffle," which some authors have appealed to in order to obtain the expected gradient, are not necessary. In our discussion, we also discuss empirical data that appear to provide additional verification of our results, as well as several everyday occurrences that provide additional support. [ABSTRACT FROM AUTHOR]

A positive relationship between local tissue temperature and perfusion exists, with isolated limb‐segment hyperthermia stimulating hyperaemia in the heated region without affecting the adjacent, non‐heated limb segment. However, whether partial‐limb segment heating evokes a heightened tissue perfusion in the heated region without directly or reflexly affecting the non‐heated tissues of the same limb segment remains unknown. This study investigated, in 11 healthy young adults, the lower limb temperature and haemodynamic responses to three levels of 1 h upper‐leg heating, none of which alter core temperature: (1) whole‐thigh (WTH; water‐perfused garment), (2) quadriceps (QH; water‐perfused garment) and (3) partial‐quadriceps (PQH; pulsed shortwave diathermy) heating. It was hypothesised that perfusion would only increase in the heated regions. WTH, QH and PQH increased local heated tissue temperature by 2.9 ± 0.6, 2.0 ± 0.7 and 2.9 ± 1.3°C (P < 0.0001), respectively, whilst remaining unchanged in the non‐heated hamstrings and quadriceps tissues during QH and PQH. WTH induced a two‐fold increase in common femoral artery blood flow (P < 0.0001) whereas QH and PQH evoked a similar ∼1.4‐fold elevation (P ≤ 0.0018). During QH and PQH, however, tissue oxygen saturation and laser‐Doppler skin blood flow in the adjacent non‐heated hamstrings or quadriceps tissues remained stable (P > 0.5000). These findings in healthy young humans demonstrate a tight thermo‐haemodynamic coupling during regional thigh heating, providing further evidence of the importance of local heat‐activated mechanisms on the control of blood circulation. What is the central question of the study?Limb‐segment hyperthermia increases perfusion without evoking haemodynamic changes in the adjacent limb‐segment: does this hold true within a small limb‐area?What is the main finding and its importance?Local whole‐thigh, quadriceps and partial‐quadriceps heating increased tissue temperature, blood flow and oxygen saturation in the heated region without affecting these parameters in the non‐heated area within the same segment. These findings further support the notion that local thermosensitive mechanisms are the primary regulators of thermal hyperaemia. [ABSTRACT FROM AUTHOR]

BACKGROUND: Mechanical factors can affect the angiogenic ability of vascular endothelial cells. How the vessel number affects the hydrodynamic properties of microvessels remains to be clarified. OBJECTIVE: To investigate the influence of vessel number on the hydrodynamics of vascular networks based on computational fluid dynamics. METHODS: Three three-dimensional models of vascular network with different vessel numbers were constructed using the Geometry module of ANSYS 19.0 software, and then the vascular network was meshed to tetrahedral elements in Mesh module. The vascular network was assumed to rigid wall without slip, and the blood was assumed to laminar, viscous, and incompressible Newtonian fluid. Blood density, velocity, and a series of blood viscosity coefficients were also established. The Navier-Stokes equation was used for calculation. Hydrodynamic properties of different parts of vascular network with different vessel numbers were analyzed and compared. RESULTS AND CONCLUSION: The streamline, velocity, and mass flow all had the same trend in the vascular network, that is, the outlet and inlet were higher and the middle junction of vascular network was lower. The more the number of vessels, the thinner the blood flow lines in each part of the vascular network. Also, the velocity, mass flow, and wall shear decreased with the increase of the number of blood vessels. Therefore, the changes in vessel number could influence the hydrodynamic environment in the vascular network. Computational fluid dynamics indicates that the changes in vessel numbers can influence the hydrodynamic properties of blood, and provides a new idea for treating bone hypoperfusion-induced diseases (fracture nonunion, bone defect, osteoporosis, etc.) through tonifying kidney and activating blood circulation based on the coupling between angiogenesis and osteogenesis. [ABSTRACT FROM AUTHOR]

Hedgehog (Hh) signaling is crucial in cardiovascular development and maintenance. However, the biological role of Patched1 (Ptch1), an inhibitory receptor of the Hh signaling pathway, remains elusive. In this study, a Ptch1 ortholog was characterized in Nile tilapia (Oreochromis niloticus), and its function was investigated through CRISPR/Cas9 gene knockout. When one-cell embryos were injected with CRISPR/Cas9 targeting ptch1, the mutation efficiency exceeded 70%. During 0–3 days post fertilization (dpf), no significant differences were observed between the ptch1 mutant group and the control group; at 4 dpf (0 day after hatching), about 10% of the larvae showed an angiogenesis defect and absence of blood flow; from 5 dpf, most larvae exhibited an elongated heart, large pericardial cavity, and blood leakage and coagulation, ultimately dying during the 6–8 dpf period due to the lack of blood circulation. Consistently, multiple differentially expressed genes related to angiogenesis, blood coagulation, and heart development were enriched in the ptch1 mutants. Furthermore, Smoothened (Smo) antagonist (cyclopamine) treatment of the ptch1 mutants greatly rescued the cardiovascular disorders. Collectively, our study suggests that Ptch1 is required for cardiovascular development and vascular integrity via Smo signaling, and excessive Hh signaling is detrimental to cardiovascular development. [ABSTRACT FROM AUTHOR]

Hemodynamics in stenosed arteries is complex, including turbulence, recirculation, and vortices, which can further worsen the disease. This study provides an overview of blood flow characteristics in stenosed arteries, focusing on flow physics, stenosis geometry, and severity. This present article examines the impact of heat and mass exchange on blood flow in arterial stenosis, taking into account chemical processes, magnetic fields, and thermal radiation. The features of vital fluid (blood) in the constricted arterial tube are examined by taking blood as Newtonian fluid in the arterial stenosis region. The continuity (mass), momentum, and concentration equations are solved using a finite difference approach with the help of appropriate boundary conditions. Solutions have been established for axial velocity, temperature, and concentration equations with variable parameters in blood circulation. It is noticed that an enhancement in the Reynolds number indicates more disorder in the velocity of the blood flow near the downstream area of cholesterol or plaque deposition. The temperature profile induced is stronger nearer to the arterial complaint wall downstream of stenosis. These findings for RBC's flow in stenosis-contained arteries have significant advantages in terms of understanding the disease mechanisms, developing accurate computational models, and identifying effective treatment strategies for patients. [ABSTRACT FROM AUTHOR]

This study investigated whether the improved performance observed with maximal self-paced single-leg (SL), compared with double-leg (DL) cycling, is associated with enhanced femoral blood flow and/or altered tissue oxygenation. The hyperaemic response to exercise was assessed in younger and older athletes. Power output was measured in 12 older (65 ± 4 y) and 12 younger (35 ± 5 y) endurance-trained individuals performing 2 x 3 min maximal self-paced exercise using SL and DL cycling. Blood flow (BF) in the femoral artery was assessed using Doppler ultrasound and muscle oxygenation was measured using near-infrared spectroscopy on the vastus lateralis. SL cycling elicited a greater power output (295 ± 83 vs 265 ± 70 W, P < 0.001) and peak femoral BF (1749.1 ± 533.3 vs 1329.7 ± 391.7 ml/min, P < 0.001) compared with DL cycling. Older individuals had a lower peak BF in response to exercise (1355.4 ± 385.8 vs 1765.2 ± 559.6 ml/min, P = 0.019) compared with younger individuals. Peak BF in response to exercise was correlated with power output during SL (r = 0.655, P = 0.002) and DL (r = 0.666, P = 0.001) cycling. The greater exercise performance during SL compared with DL cycling may be partly explained by a greater hyperaemic response when reducing active muscle mass. Despite regular endurance training, older athletes had a lower femoral BF in response to maximal self-paced exercise compared with younger athletes. [ABSTRACT FROM AUTHOR]

Dynamic light scattering (DLS) is a well known experimental approach uniquely suited for the characterization of small particles undergoing Brownian motion in randomly inhomogeneous turbid scattering medium, including water suspension, polymers in solutions, cells cultures, and so on. DLS is based on the illuminating of turbid medium with a coherent laser light and further analyzes the intensity fluctuations caused by the motion of the scattering particles. The DLS‐based spin‐off derivative techniques, such laser Doppler flowmetry (LDF), diffusing wave spectroscopy (DWS), laser speckle contrast imaging (LSCI), and Doppler optical coherence tomography (DOCT), are exploited widely for non‐invasive imaging of blood flow in brain, skin, muscles, and other biological tissues. The recent advancements in the DLS‐based imaging technologies in frame of their application for brain blood flow monitoring, skin perfusion measurements, and non‐invasive blood micro‐circulation characterization are overviewed. The fundamentals, breakthrough potential, and practical findings revealed by DLS‐based blood flow imaging studies, including the limitations and challenges of the approach such as movement artifacts, non‐ergodicity, and overcoming high scattering properties of studied medium, are also discussed. It is concluded that continued research and further technological advancements in DLS‐based imaging will pave the way for new exciting developments and insights into blood flow diagnostic imaging. [ABSTRACT FROM AUTHOR]

Alternating pressure support surface (APSS) is a common support surface for treating pressure injury in individuals with spinal cord injury (SCI). However, conflicting results on the effectiveness of APSS have been reported and may be associated with inappropriate configurations of APSS. The objectives of this study were to compare the different pressure amplitudes (75/5 mmHg [alternating between 75 and 5 mmHg] vs. 65/15 mmHg) and cycle periods (5 min [4 cycles] vs. 2.5 min [8 cycles]) of alternating pressure on sacral skin blood flow responses in 10 individuals with SCI. Sacral skin blood flow during and after loading of four alternating pressure protocols was assessed using laser Doppler flowmetry and was normalised to the value before loading (10‐min baseline, 20‐min loading and 10‐min recovery). The results demonstrated that during the high‐pressure phase, there was a significant difference between the 75/5 and 65/15 mmHg protocols (0.3658 ± 0.0688 for 75/5 mmHg and 0.1702 ± 0.0389 for 65/15 mmHg, p < 0.05); and during the low‐pressure phase, there was a significant difference between the 75/5 and 65/15 mmHg protocols (1.7184 ± 0.262 for 75/5 mmHg and 0.5916 ± 0.1378 for 65/15 mmHg, p < 0.05). There were no differences between cycle periods in skin blood flow responses. No adverse events were reported. Our finding indicates that the pressure amplitude of alternating pressure is a significant factor affecting sacral skin blood flow responses. An appropriate configuration of alternating pressure is needed to effectively increase skin blood flow and tissue viability in individuals with SCI. [ABSTRACT FROM AUTHOR]

This review spans a wide arc from the first observations of the early anatomists to the present day. William Harvey was the first to describe the heart as the centre of the large and small circulatory system. He thus replaced the previously valid system of Galenos, It was Marcello Malpighi who first described that the capillary system connects the arteries with the veins. In 1688 Antoni van Leeuwenhoek (1632–1686) confirmed these results with a paper on capillary perfusion in the caudal fin of the glass eel. It was then Hermann Boerhave (1668–1738, Leiden) who was the first to carry out microcirculation tests on patients. He studied the microcirculation in the human bulbar conjunctiva. Even today, microcirculation studies in the conjunctiva bulbi of patients are carried out today. Until 1831, it was never quite clear whether the observations reported belonged mainly to the field of microcirculation, which had not yet been defined. This was done in Great Britain by Marshall Hall (1790–1857). Technical Improvements allowed increasingly sophisticated studies of the morphological structure of the terminal vasculature. According to Gustav Ricker (1870–1948, Vienna), the terminal vasculature comprises the functional unit of the smallest arteries, arterioles, capillaries and venules. In 1921 it was still thought that the blood circulation was the sole response to the pumping action of the heart. Even the classic work by Bayliss on the myogenic hypothesis (later referred to as "blood flow autoregulation") initially received little attention. More strikingly, even the findings of August Krogh, for which he received the Nobel Prize in Medicine in 1920 (for his discovery of the mechanisms of capillary motor regulation), were ignored. During an outstanding autoregulation symposium held in 1963 a broad consensus was reached on active and passive mechanisms, which is more or less valid till today. The mechanisms of regulation of capillary blood flow are now largely understood, although not completely resolved. The development of video systems with recording capability and automated off-line recording of capillary erythrocyte velocities allowed the application of morphological and dynamic studies of cutaneous capillaries in humans. These reopened the field of physiological or pathophysiological questions again for many groups worldwide. Since 1955, many publications on "microcirculation (5423)" and "capillary microscopy (2195)" have been listed in pubmed. [ABSTRACT FROM AUTHOR]

Our study explored the impact of hypergravity on human T cells, which experience additional acceleration forces beyond Earth's gravity due to various factors, such as pulsatile blood flow, and technology, such as high-performance aircraft flights or spaceflights. We investigated the histone modifications Histone 3 lysine 4 and 9 trimethylation (H3K4me3 and H3K9me3, respectively), as well as the structural and cytoskeletal organization of Jurkat T cells in response to hypergravity. Histone modifications play a crucial role in gene regulation, chromatin organization and DNA repair. In response to hypergravity, we found only minimal changes of H3K4me3 and a rapid increase in H3K9me3, which was sustained for up to 15 min and then returned to control levels after 1 h. Furthermore, rapid changes in F-actin fluorescence were observed within seconds of hypergravity exposure, indicating filament depolymerization and cytoskeletal restructuring, which subsequently recovered after 1 h of hypergravity. Our study demonstrated the rapid, dynamic and adaptive cellular response to hypergravity, particularly in terms of histone modifications and cytoskeletal changes. These responses are likely necessary for maintaining genome stability and structural integrity under hypergravity conditions as they are constantly occurring in the human body during blood cell circulation. [ABSTRACT FROM AUTHOR]

Understanding potential disease causation due to stenosis and thrombosis and its treatment by utilising catheters and magnetic field has gained increasing attention from experts worldwide. Endothelial injury or plaque rupture can trigger thrombosis, which can cut off the supply of blood to the heart or brain, causing stroke or a myocardial infarction. In the regions of stenosis, narrowing of lumen of arteries and high shear rate generate conditions that increase platelet build-up and blockage. Treatment like catheters and magnetic field are famously being implemented in modern medicine as a way of removing blood clots inside a constricted artery in light to improve the blood circulation inside a human body. This article reviews the impact of the simultaneous presence of stenosis and thrombosis on rheological properties of blood flow and the effects of using catheter in clearing the obstructions in the inner wall of blood vessel. We also introduce significant recent development on blood flow modelling relating to the subject matter. A sample mathematical model is considered from the literature to explain the influence of aforesaid arterial constrictions and clinical therapy for future directions in the medical field. Based on the collected literature, we note that the angioplasty catheter greatly increases blood flow as compared to infusion and guidewire catheters because it uses a balloon-tipped catheter to remove occlusions in the artery lumen. This comprehensive review and the proposed mathematical model together with the clinical data may offer directions for further studies, especially on one specific type of catheter for balloon angioplasty as the best treatment for clearing the occlusions in the diseased artery. [ABSTRACT FROM AUTHOR]

Background: Erectile dysfunction (ED) is a common diabetes-related complication. Materials and methods: This study examined the effect of daily low-dose tadalafil (5mg) on patients' quality of life (including that of sex life) and blood circulation. Erectile dysfunction questionnaires were administered to 20 patients with type 2 diabetes (T2DM) and ED. The safety and efficacy of tadalafil were evaluated using laboratory tests, and the effect on blood circulation was measured through nail fold capillaroscopy. Results: Daily tadalafil use by patients with T2DM and ED showed a statistically significant increase in the erectile reliability score from of 1.15 to 3.20 (p < .00012). Capillary blood circulation improvement tests showed a statistically significant increase in apical limb width from 13.1 to 14.64 mm (p = .04829) and flow from 9035 to 11946 µm³/s (p = .04405). Although not significant, increased capillary width and speed (rate of blood flow) confirmed improved blood circulation. There were no significant changes in the cardiac indicators (troponin, prostate-specific antigen, or electrocardiogram tests) before and after tadalafil administration, supporting the safety of its low-dose daily administration. Conclusions: A small dose of daily tadalafil was shown to safely improve erectile dysfunction and peripheral blood flow in patients with T2DM, in which peripheral arterial diseases should not be considered separately but rather as complex entities. [ABSTRACT FROM AUTHOR]

This article scrutinizes blood circulation through an artery having magnetized hybrid nanoparticles (silver and gold) with multiple stenoses at the outer walls and erratic thrombus of different radii at the center. In the realm of biomedical innovation, magnetized hybrid nanoparticles emerge as a captivating frontier. These nanoparticles, amalgamating diverse materials, exhibit magnetic properties that engender novel prospects for targeted drug delivery, medical imaging enhancement, and therapeutic interventions. The study was carried out employing modern bio-fluid dynamics (BFD) software. In this iterative procedure, a second-order finite difference approach is used to solve the governing equations with 0.005 tolerance. The experiment is performed on a blood conduit with mild stenosis assumptions, and expressions of temperature, resistance impedance to flow, velocity, wall shear stress, and pressure gradient are generated by employing related boundary conditions. No one has ever attempted to acquire the remedial impact of an induced magnetic field and hybrid nanoparticles on the bloodstream in a tapering artery containing multiple stenoses on the outside walls and multi-thrombus at the center using 3-D bio-fluid simulation. Furthermore, the study's findings are unique, and these computational discoveries were not previously published by any researcher. The findings suggest that hybrid nanoparticles can be used as medication carriers to reduce the impact of thrombosis and stenosis-induced resistance to blood flow or coagulation-related factors. [ABSTRACT FROM AUTHOR]

The brain has a well-developed vascular network that allows it to consume up to 15% of cardiac output at its low weight relative to the whole-body weight. Normally, metabolic demands of the brain depend considerably on the intensity of functioning of its different regions, which requires a continuous local blood flow regulation. On the other hand, the state of systemic hemodynamics exert a significant impact on the organ blood flow. Complex and multilevel regulatory mechanisms of cerebral blood flow are aimed at minimizing possible adverse effects of systemic hemodynamic disorders. The importance of a precise and prompt cerebral blood flow regulation is reinforced by the lack of energy reserves or substrates for autonomous energy production in nervous tissue. The major mechanisms of cerebral blood flow regulation include myogenic regulation, local exposures to systemic blood flow humoral factors and vasoactive substances (hormones, metabolites), changes in blood gas composition (rises and falls in blood oxygen or carbon dioxide tension). Moreover, there are endothelium-dependent regulatory mechanisms. Yet another level of cerebrovascular tone regulation is represented by the impact of neurotransmitters released from vasomotor nerve terminals of sympathetic and parasympathetic divisions of the autonomic nervous system, as well as from synaptic endings of subcortical neurons and cortical interneurons. The present review addresses the principles of neurogenic regulation of cerebral blood flow. Neurogenic vascular tone regulation is the most complex regulatory circuit. The autonomic cerebrovascular innervation has significant features that distinguish it from that in most other organs of the great circle of blood circulation. Apart from autonomic innervation as such, brain vessels receive sensory inputs, while small intracerebral arterioles are additionally innervated directly by the neurons of subcortical nuclei and by cortical interneurons. Therefore, a deeper insight into the molecular mechanisms of cerebral blood flow neurogenic regulation may serve as a basis for the development of new neuromodulation-based therapeutic approaches to severe brain diseases. [ABSTRACT FROM AUTHOR]

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The heart is widely acknowledged as the unique driver of blood circulation. Recently, we discovered a flow-driving mechanism that can operate without imposed pressure, using infrared (IR) energy to propel flow. We considered the possibility that, by exploiting this mechanism, blood vessels, themselves, could propel flow. We verified the existence of this driving mechanism by using a three-day-old chick-embryo model. When the heart was stopped, blood continued to flow for approximately 50 minutes, albeit at a lower velocity. When IR was introduced, the postmortem flow increased from ~41.1 ± 25.6 μm/s to ~153.0 ± 59.5 μm/s (n = 6). When IR energy was diminished under otherwise physiological conditions, blood failed to flow. Hence, this IR-dependent, vessel-based flow-driving mechanism may indeed operate in the circulatory system, complementing the action of the heart. [ABSTRACT FROM AUTHOR]

The purpose of this study was to study the blood circulation in large blood vessels and in the abdominal organs during inflammation of the abdominal cavity. Using the method of rheograph and laser ultrasonic dopplerography, the blood flow velocity in the abdominal aorta and inferior vena cava was studied. The circulatory system maintains the stability of the body in violation of internal organs and tissues.In large blood vessels and organs of the abdominal cavity, inflammation leads to disruption of blood supply in the microvasculature of the vessel. The rate of blood flow in the main vessel in acute inflammation of the abdominal cavity decreased compared to the control group. The resistance index in the main vessel RI decreased by 38.3%, which is associated with an increase in the diameter of the main vessel. With inflammation of the abdominal cavity, an increase in the velocity of blood flow in the portal vein and abdominal aorta was recorded.As a result of a decrease in the tone of blood vessels after a violation of liver function, the blood supply to the abdominal cavity decreased. The decrease in the functional properties of arteries and veins led to a decrease in blood flow in the abdominal cavity, which, in turn, manifests itself as a result of the preservation of microcirculatory disorders. [ABSTRACT FROM AUTHOR]

This paper's goal is to investigate a mathematical model of Darcy Forchheimer flow of a tri-hybrid nanofluid consisting of pure blood as the base fluid and ZrO2, AA7072 and AA7075 as nanoparticles flowing via a porous channel, which might be used as a model for drug administration. Some appropriate transformations are implemented to transmute the governing system of partial differential equations and the relevant boundary conditions for computation. The NDsolve is employed to generate the numerical solution for the relevant system of differential expression. The properties of flow patterns of tri-hybrid nanofluids are simulated and investigated in great depth due to the variation in the changing factors, such as temperature, velocity, and profiles. ZrO2 + AA7072 + AA7075/blood, ZrO2 + AA7072/blood and ZrO2/blood have their rates, momentum, and heat transfer studied in detail, as have the effects of applicable limitations on these variables. Amongst the various findings of this study is the fact that elevating the Forchheimer number slows the flow velocity of the tri-hybrid nanofluid and enhances the temperature profile. This theoretical model is comprised of Forchheimer number that occurs through blood flow. It has a significant bearing on the magnetic delivery in blood, the therapeutic procedure of hyperthermia, magnetic endoscopy, understanding and regulating blood flow, transport of complex bio-waste fluids, and heat transfer in capillaries, amongst other things. [ABSTRACT FROM AUTHOR]

Simple Summary: Pregnancy requires major adaptions to blood circulation in the mother, because the developing baby needs an increasing supply of nutrients from the mother to grow. We know that this blood circulation can be influenced by position, for example, when the mother sits, stands or lies on her back. Some positions, like lying on the back, can increase risk of pregnancy loss. We present research that provides evidence for how blood supply is changed by both pregnancy and position. The primary aim of this work is to provide a description of what is expected in a normal pregnancy, so that we can provide a basis for future studies that investigate pregnancies that are not going as well as they should. The maternal cardiovascular-circulatory system undergoes profound changes almost from the conception of a pregnancy until the postpartum period to support the maternal adaptions required for pregnancy and lactation. Maintenance of cardiovascular homeostasis requires changes in the cardiovascular autonomic responses. Here, we present a longitudinal study of the maternal cardiovascular autonomic responses to pregnancy and maternal position. Over a normal gestation, in the left lateral position there are significant changes in both time and frequency domain parameters reflecting heart rate variability. We show that cardiovascular autonomic responses to physiological stressors (standing and supine positions in late pregnancy) became significantly different with advancing gestation. In the third trimester, 60% of the subjects had an unstable heart rate response on standing, and these subjects had a significantly reduced sample entropy evident in their heart rate variability data. By 6 weeks, postpartum function returned to near the non-pregnant state, but there were consistent differences in high-frequency power when compared to nulligravid cases. Finally, we review complementary evidence, in particular from magnetic resonance imaging, that provides insights into the maternal and fetal impacts of positioning in pregnancy. This demonstrates a clear relationship between supine position and maternal hemodynamic parameters, which relates to compression of the inferior vena cava (p = 0.05). Together, these studies demonstrate new understanding of the physiology of physiological stressors related to position. [ABSTRACT FROM AUTHOR]

Use of thoracoabdominal normothermic regional perfusion (TA-NRP) during donation after circulatory death (DCD) is an important advance in organ donation. Prior to establishing TA-NRP, the brachiocephalic, left carotid, and left subclavian arteries are ligated, thereby eliminating anterograde brain blood flow via the carotid and vertebral arteries. While theoretical concerns have been voiced that TA-NRP after DCD may restore brain blood flow via collaterals, there have been no studies to confirm or refute this possibility. We evaluated brain blood flow using intraoperative transcranial Doppler (TCD) in two DCD TA-NRP cases. Pre-extubation, anterior and posterior circulation brain blood flow waveforms were present in both cases, similar to the waveforms detected in a control patient on mechanical circulatory support undergoing cardiothoracic surgery. Following declaration of death and initiation of TA-NRP, no brain blood flow was detected in either case. Additionally, there was absence of brainstem reflexes, no response to noxious stimuli and no respiratory effort. These TCD results demonstrate that DCD with TA-NRP did not restore brain blood flow. [ABSTRACT FROM AUTHOR]

The delivery to and utilization of oxygenated hemoglobin to the forearm muscles are key determinants of rock-climbing performance. Anthocyanin-rich New Zealand blackcurrant (NZBC) has been suggested to improve blood flow and may enhance forearm endurance performance. As such, a double-blind, randomized crossover design study with 12 participants performed submaximal intermittent contractions (at 40% maximal voluntary contraction) to failure after a 7-day intake of 600 mg/day NZBC extract or placebo. Minimum tissue saturation index (TSI%) was assessed during the contractions. During recovery, time to half recovery of TSI% and brachial artery blood flow were assessed. There was no difference in time to exhaustion between NZBC and placebo. Minimum TSI% was lower with NZBC extract (43 ± 8 vs. 50 ± 11 TSI%; p = .007; Cohen's d = 1.01). During recovery, there was no effect on brachial artery blood flow. However, time to half recovery was faster with NZBC (26 ± 17 vs. 42 ± 26 s; p = .001; Cohen's d = 1.3) following exhaustive contractions. Seven days of NZBC extract appears to improvemuscle oxygenation during and following contractions with no change in either arterial blood flow or forearm endurance performance. [ABSTRACT FROM AUTHOR]

Nasosinusitis is the main cause of the olfactory disorder, and this kind of olfactory disorder is persistent and difficult to cure, which is in line with the pathogenesis of chronic and prolonged diseases “long” and “ persistent” in the theory of “ chronic diseases affecting collaterals”. Traditional Chinese medicine ( TCM ) believes that collateral diseases are caused by the coagulation of phlegm and accumulation of blood stasis. This paper analyzes the evolution of the pathogenesis according to the three stages of pathogenic factors invasion the collateral by the method of cross-referencing between TCM and western medicine, and conclude that in the initial stage of nasosinusitis-related olfactory disorder, external pathogen attacks the collateral and phlegm and turbidity are internally produced; in the middle stage, phlegm retention occurs in the lung collateral and blood flow is blocked due to coagulation; and in the final stage, the binding of phlegm and stasis occurs, and the collateral is injured by turbidity and toxicity. Treatment is based on clearing turbidity and phlegm, promoting blood circulation and removing blood stasis, and eliminating pathogenic factors and resolving toxins. In addition, there are modern studies of biological mechanisms underlying nasosinusitis-related olfactory disorder, such as microcirculation disturbance, increased levels of inflammatory factors, disturbances in lipid metabolism, and induction of apoptosis, which provide a scientific basis for understanding and treating the disease from the viewpoint of phlegm and stasis. In this paper, the purpose of exploring nasosinusitis-related olfactory disorder caused by phlegm and stasis is to provide patients with new ideas of TCM treatment, and to provide a better TCM treatment solution for patients with limited access to western medicine. [ABSTRACT FROM AUTHOR]

Background: Glomerular filtration rate (GFR) is a key measure of kidney function but often inaccurately ascertained by serum creatinine and cystatin C in pediatrics. In this pilot trial, we evaluated the relationship between GFR calculated by using phase-contrast MRI (PC-MRI) biomarkers and GFR by 125I-iothalamate clearance in youth undergoing bone marrow transplantation (BMT). Methods: A total of twenty-one pediatric BMT candidates (8–21 years of age) were recruited for a research kidney PC-MRI. After completion of 125I-iothalamate clearance, same-day PC-MRI measurements were completed of the kidney circulation without a gadolinium-based contrast agent. MRI included a non-contrast balanced-SSFP–triggered angiography to position ECG-gated breath-held 2D PC-MRI flow measurements (1.2 × 1.2 × 6 mm3). A multivariate model of MRI biomarkers estimating GFR (GFR-MRI) was selected using the elastic net approach. Results: The GFR-MRI variables selected by elastic net included average heart rate during imaging (bpm), peak aorta flow below the kidney artery take-offs (ml/s), average kidney artery blood flow, average peak kidney vein blood flow, and average kidney vein blood flow (ml/s). The GFR-MRI model demonstrated strong agreement with GFR by 125I-iothalamate (R2 = 0.65), which was stronger than what was observed with eGFR by the full age spectrum and Chronic Kidney Disease in Children under 25 (CKiD U25) approaches. Conclusion: In this pilot study, noninvasive GFR-MRI showed strong agreement with gold standard GFR in youth scheduled for BMT. Further work is needed to evaluate whether non-contrast GFR-MRI holds promise to become a superior alternative to eGFR and GFR by clearance techniques. [ABSTRACT FROM AUTHOR]

Radiation-induced lymphopenia has gained attention recently as the result of its correlation with survival in a range of indications, particularly when combining radiation therapy (RT) with immunotherapy. The purpose of this study is to use a dynamic blood circulation model combined with observed lymphocyte depletion in patients to derive the in vivo radiosensitivity of circulating lymphocytes and study the effect of RT delivery parameters. We assembled a cohort of 17 patients with hepatocellular carcinoma treated with proton RT alone in 15 fractions (fx) using conventional dose rates (beam-on time [BOT], 120 seconds) for whom weekly absolute lymphocyte counts (ALCs) during RT and follow-up were available. We used HEDOS, a time-dependent, whole-body, blood flow computational framework, in combination with explicit liver blood flow modeling, to calculate the dose volume histograms for circulating lymphocytes for changing BOTs (1 second-300 seconds) and fractionations (5 fx, 15 fx). From this, we used the linear cell survival model and an exponential model to determine patient-specific lymphocyte radiation sensitivity, α , and recovery, σ, respectively. The in vivo–derived patient-specific α had a median of 0.65 Gy −1 (range, 0.30-1.38). Decreasing BOT to 1 second led to an increased average end-of-treatment ALC of 27.5%, increasing to 60.3% when combined with the 5-fx regimen. Decreasing to 5 fx at the conventional dose rate led to an increase of 17.0% on average. The benefit of both increasing dose rate and reducing the number of fractions was patient specificࣧpatients with highly sensitive lymphocytes benefited most from decreasing BOT, whereas patients with slow lymphocyte recovery benefited most from the shorter fractionation regimen. We observed that increasing dose rate at the same fractionation reduced ALC depletion more significantly than reducing the number of fractions. High-dose-rates led to an increased sparing of lymphocytes when shortening the fractionation regimen, particularly for patients with radiosensitive lymphocytes at elevated risk. [ABSTRACT FROM AUTHOR]

Purpose: To assess the effect of antenatal umbilical coiling index on Doppler parameters of umbilical cord vessels. Material and Methods: This cross-sectional analytical study was conducted in a large health services hospital and a total of 48 pregnant women were included in the study. These women were 28-42 weeks of gestation. Transabdominal sonography was used to study the antenatal umbilical coiling index and its relationship with Doppler parameters of umbilical vessels’ blood flow . Results: The mean gestational age of was 31.47 ± 2.45 weeks. The antenatal umbilical coiling index was found to be 0.42 ± 0.1 with values 0.27 and 0.57 being 10th and 90th percentile, respectively. In terms of the coiling pattern, 8% exhibited hypercoiling, 10% showed hypocoiling, and the remaining 82% were classified as normocoiled. There was a non-significant correlation of UCI with PSV (r=0.202, P=0.169) and RI (r=0.018, P=0.905) of umbilical arteries. The correlation of UCI with umbilical vein velocity (r=0.432, P=0.002) and blood flow rate (r=0.668, P=0.00) was strong and significant. Conclusion: The antenatal umbilical coiling index can be assessed on ultrasonography and there was a significant relationship between the Doppler flow parameters of umbilical vein and the umbilical coiling index. Our study showed that umbilical coiling does promote venous blood flow in the umbilical vein. Moreover, there was a non-significant relationship between the umbilical coiling index and the Doppler flow parameters of umbilical arteries. [ABSTRACT FROM AUTHOR]

Takayasu arteritis (TAK) is a chronic granulomatous vasculitis with an unknown etiology that often manifests over time. It has a dismal prognosis and is currently clinically refractory. The theory of poisonous evil has drawn more attention in recent years in the treatment of autoimmune disorders. Poisonous evil tends to accumulate and transform into heat, which causes a variety of symptoms to gradually emerge. Our team believes that the main cause of TAK is the prolonged stagnation of poisonous evil, the transformation of heat into fire, and the damage to the vessels and collaterals. Blood stasis is the basic pathogenesis. This disease is located in the blood vessels, which is also closely related to the spleen and kidney. TAK also belongs to a deficiency in origin and excess in superficislity. Kidney and spleen deficiencies, and a lack of essence and blood, cause only partially filled blood vessels and restricted blood flow. The collection of evil qi and the transformation of heat-toxin culminates in the accumulation of heat-toxin and congestion of blood vessels. The illness persists and the evil qi remains and penetrates the internal organs, causing a lack of vital qi, and the viscera loses its nourishment. Unblocking the blood vessels and boosting blood circulation is the cornerstone of clinical treatment. The focus of treatment is on removing heat-toxin during the active phase, while during the remission phase, the focus is on strengthening the spleen and kidney, nourishing the vessels, taking into consideration detoxification, and dredging collaterals. The goal of the cicatricial period is to dredge collaterals in order to enrich vital qi. Based on relevant theories of traditional Chinese medicine and pathological mechanisms research of western medicine, the significance of heat-toxin in the pathogenesis of TAK is explained. Our team believes that the heat-toxin in blood vessels developing into lumps is the vasculature are the cause of the disease's morbidity. The heat-toxin can be cleared to remove blood stasis and eliminate lumps, which will improve clinical symptoms, slow the disease's progression, and provide ideas for clinical treatment. [ABSTRACT FROM AUTHOR]

Human thermoregulation is governed by a complex, nonlinear feedback control system. The system consists of thermoreceptors, a controller, and effector mechanisms for heat exchange that coordinate to maintain a central core temperature. A principal route for heat flow between the core and the environment is via convective circulation of blood to arteriovenous anastomoses located in glabrous skin of the hands and feet. This paper presents new human experimental data for thermoregulatory control behavior along with a coupled, detailed control system model specific to the interdependent actions of core temperature and glabrous skin blood flow (GSBF) under defined transient environmental thermal stress. The model was tuned by a nonlinear least-squared curve fitting algorithm to optimally fit the experimental data. Transient GSBF in the model is influenced by core temperature, nonglabrous skin temperature, and the application of selective thermal stimulation. The core temperature in the model is influenced by integrated heat transfer across the nonglabrous body surface and GSBF. Thus, there is a strong cross-coupling between GSBF and core temperature in thermoregulatory function. Both variables include a projection term in the model based on the average rates of their change. Six subjects each completed two thermal protocols to generate data to which the common model was fit. The model coefficients were unique to each of the twelve data sets but produced an excellent agreement between the model and experimental data for the individual trials. The strong match between the model and data confirms the mathematical structure of the control algorithm. [ABSTRACT FROM AUTHOR]

It is of increasing importance to understand and predict changes to the systemic and pulmonary circulations in pulmonary hypertension (PH). To do so, it is necessary to describe the circulation in complete quantitative terms. Characteristic impedance (Zc) expresses opposition of the circulation to pulsatile blood flow. Evaluation of systemic and pulmonary Zc relationships according to PH classification has not previously been described. Prospective study of 40 clinically indicated patients referred for CMR and RHC (56 ± 18 years; 70% females, eight mPAP ≤ 25 mmHg, 16 pre‐capillary [Pre‐cPH], eight combined pre‐ and post‐capillary [Cpc‐PH] and eight isolated left‐heart disease [Ipc‐PH]). CMR provided assessment of ascending aortic (Ao) and pulmonary arterial (PA) flow, and RHC, central Ao and PA pressure. Systemic and pulmonary Zc were expressed as the relationship of pressure to flow in the frequency domain. Baseline demographic characteristics were well‐matched across PH subclasses. In those with a mPAP ≤25mHg, systemic Zc and SVR were >2 times higher than pulmonary Zc and PVR. Only Pre‐cPH was associated with inverse pulsatile (systemic Zc 58 [45–69] vs pulmonary Zc 70 [58–85]), but not steady‐state (SVR 1101 [986–1752] vs. PVR 483 [409–557]) relationships. Patients with CpcPH and IpcPH had concordant pulsatile and steady‐state relationships (Graphical Abstract). Measurement of, and the relationship between, systemic and pulmonary Zc in patients according to PH sub‐classification has not previously been described. Systemic Zc was routinely higher than pulmonary Zc, except in patients with newly diagnosed Pre‐cPH, where inverse pulsatile but not steady‐state relationships were observed. [ABSTRACT FROM AUTHOR]

Numerous biomaterials have been developed for application in blood‐contacting medical devices to prevent thrombosis; however, few materials have been applied to full‐scale devices and evaluated for hemocompatibility under clinical blood flow conditions. We applied a dual‐action slippery liquid‐infused (LI) nitric oxide (NO)‐releasing material modification (LINO) to full‐scale blood circulation tubing for extracorporeal lung support and evaluated the tubing ex vivo using swine whole blood circulated for 6 h at a clinically relevant flow. LINO tubing was compared to unmodified tubing (CTRL) and isolated LI and NO‐releasing modifications (n = 9/group). The primary objective was to evaluate safety and blood compatibility of this approach, prior to progression to in vivo testing of efficacy in animal models. The secondary objective was to evaluate coagulation outcomes relevant to hemocompatibility. No untoward effects of the coating, such as elevated methemoglobin fraction, were observed. Additionally, LINO delayed platelet loss until 6 h versus the reduction in platelet count in CTRL at 3 h. At 6 h, LINO significantly reduced the concentration of platelets in an activated P‐selectin expressing state versus CTRL (32 ± 1% decrease, p =.02). Blood clot deposition was significantly reduced on LINO blood pumps (p =.007) and numerically reduced on tubing versus CTRL. Following blood exposure, LINO tubing continued to produce a measurable NO‐flux (0.20 ± 0.06 × 10−10 mol cm−2 min−1). LINO is a potential solution to reduce circuit‐related bleeding and clotting during extracorporeal organ support, pending future extended testing in vivo using full‐scale extracorporeal lung support devices. [ABSTRACT FROM AUTHOR]

Injection of fillers for soft tissue augmentation can lead to a variety of complications, among which vascular occlusion caused by intravascular injection of filler will induce severe or permanent damage. The treatment strategies for intravascular embolization caused by injection include warm compress application, but the exact beneficial effects of this therapy have not been confirmed. The purpose of this study is to construct an intravascular injection embolism model and observe the effectiveness of warm and cold compress through a randomized, controlled trial. Thirty rabbit's sixty ears were randomly divided into warm compress group, cold compress group, and control group. Polymethyl methacrylate (PMMA) was slowly injected into the central ear artery (CEA) to cause vascular embolism. Warm compress and cold compress treatment were performed respectively. The vascular recanalization and other related indexes were observed at 30 min, 1 day, and 7 days after injection, and the tissue necrosis was analyzed at 7 days. In the early stage of vascular embolization, warm compress can immediately promote vascular dilatation, blood circulation and partial blood flow recovery. One day after intravascular injection, warm compress can reduce intravascular embolization and reduce the incidence of tissue necrosis. At 7 days after intravascular injection, the vessels in the cold compress and control groups were still embolized while the percentage of recanalization in the warm compress group was 47.4% (P < 0.000). Early-stage warm compress after intravascular PMMA injection is conducive to recanalization of vascular embolization and reducing tissue necrosis. [ABSTRACT FROM AUTHOR]

Retained products of conception (RPOC) is a condition in which trophoblastic tissue remains in the uterus after pregnancy, causing massive hemorrhage in some cases. Though RPOC is commonly treated by intrauterine curettage or hysteroscopic resection uterine artery embolization or hysterectomy may be performed in case of massive bleeding. We experienced two cases of RPOC after surgery for missed abortion that failed to respond to conservative treatment and required surgical treatment. They were treated by hysteroscopic resection with temporary balloon catheter occlusion of bilateral internal iliac arteries for fertility preservation. After the balloon catheters were inflated, the reduction of blood flow to RPOC was observed under transvaginal ultrasound. In both cases, good visualization was maintained throughout the surgery with minimal bleeding. They were discharged the next day and resumed menstruation 1 month after surgery. This paper demonstrates the usefulness of this procedure as a minimally invasive and fertility‐preserving surgery. [ABSTRACT FROM AUTHOR]

Aortic disease has a significant impact on quality of life. The involvement of the aortic arch requires the preservation of blood supply to the brain during surgery. Deep hypothermic circulatory arrest is an established technique for this purpose, although neurological injury remains high. Additional techniques have been used to reduce risk, although controversy still remains. A three-way cannulation approach, including both carotid arteries and the femoral artery or the ascending aorta, has been used successfully for aortic arch replacement and redo procedures. We developed circuits of the circulation to simulate blood flow during this type of cannulation set up. The CARDIOSIM© cardiovascular simulation platform was used to analyse the effect on haemodynamic and energetic parameters and the benefit derived in terms of organ perfusion pressure and flow. Our simulation approach based on lumped-parameter modelling, pressure–volume analysis and modified time-varying elastance provides a theoretical background to a three-way cannulation strategy for aortic arch surgery with correlation to the observed clinical practice. [ABSTRACT FROM AUTHOR]

Patent ductus venosus is an extremely rare form of congenital portosystemic shunt that results in the diversion of portal blood into the systemic circulation, decreasing hepatic blood flow and increasing blood volume and toxic substances in the systemic circulation. We present a clinical case of a male infant born at 37 5/7 weeks gestational age with patent ductus venosus. Because very few cases of patent ductus venosus have been reported, the prudent approach it would be to perform serial Doppler studies and laboratory tests to follow the course of the ductus venosus until closure and to intervene if the infant becomes unstable and symptomatic. The medical team decided that the conservative management in this case was a better choice, since the infant remained stable with good growth. [ABSTRACT FROM AUTHOR]

Seven-day intake of anthocyanins from New Zealand blackcurrant (NZBC) extract increased cardiac output and femoral artery diameter during a sustained submaximal isometric contraction. It is not known if there are intake duration effects by NZBC extract on the isometric contraction-induced cardiovascular responses. In a repeated measures design, male participants (n = 19, age: 26 ± 4 years) performed a 120-second submaximal (30%) isometric contraction of the knee extensors at baseline and following 1, 4 and 7-days intake of 600 mg·day−1 NZBC extract. During the 120-second submaximal isometric contraction, femoral artery diameter and cardiovascular responses were measured with ultrasound and beat-to-beat hemodynamic monitoring. Femoral artery was larger following 4-days (mean difference = 0.046 cm, 95% CI [0.012, 0.080], p = 0.005) and 7-days (mean difference = 0.078 cm, 95% CI [0.034, 0.123], p < 0.001) in comparison to baseline with no increase with 1-day intake. Systolic and diastolic blood pressure, heart rate and total peripheral resistance were not changed by NZBC extract at 1, 4 and 7-days intake. However, mean arterial pressure, stroke volume, cardiac output and total peripheral resistance were changed at time points during the isometric contraction following 7-days intake in comparison to 1-day intake of NZBC extract (p < 0.05). Alterations in femoral artery diameter and some cardiovascular responses during a submaximal sustained isometric contraction of the knee extensors are affected by the intake duration of New Zealand blackcurrant extract, with no effects by 1-day intake. Our observations suggest that the bioavailability of blackcurrant anthocyanins and anthocyanin-derived metabolites is required for days to alter the mechanisms for isometric-contraction induced cardiovascular responses. [ABSTRACT FROM AUTHOR]

The current article primarily focuses on the peristaltic flow of hybrid nanofluid containing (Cu) and (Ag) as nanoparticles and blood is considered as a carrier fluid in a symmetric channel. The fundamental equations such as momentum, energy, and concentration are mathematically modeled under the consideration of mixed convection, thermal radiation, Joule heating, viscous dissipation, and heat sink/source effects. The effects of an inclined magnetic field are also added since it plays an essential role in blood flow through arteries. Heat source/sink effects are considered to maintain the homogeneous temperature to improve blood circulation. Moreover, the flow characteristics of homogeneous–heterogeneous reactions are also elaborated. To overcome the complexity of the mathematical system, an assumption of small Reynolds number (i.e., Re → 0 ) and long-wavelength is utilized. Built-in numerical solver, i.e., ND-Solve is used to attain numerical results. The graphical influence of embedded parameters on flow quantities is graphically analyzed and discussed physically. The inclined magnetic field has an increasing impact on fluid velocity while reducing fluid temperature. The homogeneous/heterogeneous reaction parameters depict an opposite behavior on the chemical distribution of species (f(y)). For larger magnetic inclination angles (ξ) , the size of the trapped bolus enhances. [ABSTRACT FROM AUTHOR]

Background and Purpose: Capillary arterialization, characterized by the coverage of pre‐existing or nascent capillary vessels with vascular smooth muscle cells (VSMCs), is critical for the development of collateral arterioles to improve post‐ischaemic blood flow. We previously demonstrated that the inhibition of transient receptor potential 6 subfamily C, member 6 (TRPC6) channels facilitate contractile differentiation of VSMCs under ischaemic stress. We here investigated whether TRPC6 inhibition promotes post‐ischaemic blood flow recovery through capillary arterialization in vivo. Experimental Approach: Mice were subjected to hindlimb ischaemia by ligating left femoral artery. The recovery rate of peripheral blood flow was calculated by the ratio of ischaemic left leg to non‐ischaemic right one. The number and diameter of blood vessels were analysed by immunohistochemistry. Expression and phosphorylation levels of TRPC6 proteins were determined by western blotting and immunohistochemistry. Key Results: Although the post‐ischaemic blood flow recovery is reportedly dependent on endothelium‐dependent relaxing factors, systemic TRPC6 deletion significantly promoted blood flow recovery under the condition that nitric oxide or prostacyclin production were inhibited, accompanying capillary arterialization. Cilostazol, a clinically approved drug for peripheral arterial disease, facilitates blood flow recovery by inactivating TRPC6 via phosphorylation at Thr69 in VSMCs. Furthermore, inhibition of TRPC6 channel activity by pyrazole‐2 (Pyr2; BTP2; YM‐58483) promoted post‐ischaemic blood flow recovery in Apolipoprotein E‐knockout mice. Conclusion and Implications: Suppression of TRPC6 channel activity in VSMCs could be a new strategy for the improvement of post‐ischaemic peripheral blood circulation. [ABSTRACT FROM AUTHOR]

Background: Transcutaneous electrical nerve stimulation (TENS) uses different combinations of frequency (low or high), excitation threshold (motor or sensory), and site of application (local or ganglion). Objectives: The present study aimed to investigate the acute effect of TENS on hemodynamic variables in different populations and to determine whether differences exist between low-frequency (< 10 Hz) and high-frequency (≥ 10 Hz) TENS, between motor and sensory excitability thresholds, and between local or ganglionic application. Methods: The Cochrane, EMBASE, SCOPUS, CINAHL, and PUBMED databases were searched for randomized clinical trials in which TENS was administered noninvasively with surface electrodes in the adult population (subjects aged 18 years or older). Results: Thirteen articles met eligibility criteria and included a total of 371 subjects. The outcomes were the effects of TENS on blood flow, peripheral vascular resistance, heart rate, systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean blood pressure (MBP). A moderate increase in blood flow was noted when high frequencies were applied at the sensory threshold and above the ganglion. A decrease in peripheral vascular resistance was noted when TENS was administered at the sensory threshold above the ganglion. Significant changes in MBP and DBP were noted when high frequencies were administered at the sensory threshold and a significant difference in MBP was noted when TENS was administered locally. Conclusion: The results show that TENS can modify hemodynamic responses. Moreover, it is important to determine the frequency, excitability threshold, and site of application to achieve the expected results. [ABSTRACT FROM AUTHOR]

Purpose: Vasovagal syncope is thought to be mediated by a progressive fall in cardiac output secondary to venous pooling of blood in the splanchnic circulation. How and when this occurs before syncope has not been determined.A total of 20 patients who became hypotensive during head-up tilt (age 40.9 ± 3.4 years; 10 females) were divided into two groups—the glyceryl trinitrate (GTN) group (n = 12) and the vasovagal syncope (VVS) group (n = 8) – on the basis of whether or not nitroglycerine provocation was required. They were compared with a control group (age 38.6 ± 3.3; 8 females; n = 13). Hemodynamics, including superior mesenteric artery blood flow (SMABF) and muscle sympathetic nerve activity (MSNA) were recorded continuously during early tilt, presyncope and recovery. We used pixel-weighting to calculate average velocity from the pulsed Doppler velocity envelope.During baseline and early tilt, resistance to mesenteric blood flow was lower in the VVS group: 0.30 ± 0.02 to 0.30 ± 0.02 mmHg/ml/min versus controls 0.30 ± 0.03 to 0.38 ± 0.04 mmHg/ml/min (p = 0.05). During presyncope, as blood pressure and stroke volume gradually fell, SMABF was higher in the VVS group, falling from 370 ± 46 to 248 ± 35 ml/min, versus controls, falling from 342 ± 51 to 233 ± 19 (p = 0.03). At this time, MSNA was lower in the VVS group than controls: 39 ± 4 to 34 ± 3 bursts/min versus 45 ± 2 to 48 ± 3 (p = 0.001).During presyncope, increased splanchnic blood flow may pool more blood in capacitance vessels resulting in decreased venous return and cardiac output. This may be secondary to decreased vasoconstrictor sympathetic activity.Methods: Vasovagal syncope is thought to be mediated by a progressive fall in cardiac output secondary to venous pooling of blood in the splanchnic circulation. How and when this occurs before syncope has not been determined.A total of 20 patients who became hypotensive during head-up tilt (age 40.9 ± 3.4 years; 10 females) were divided into two groups—the glyceryl trinitrate (GTN) group (n = 12) and the vasovagal syncope (VVS) group (n = 8) – on the basis of whether or not nitroglycerine provocation was required. They were compared with a control group (age 38.6 ± 3.3; 8 females; n = 13). Hemodynamics, including superior mesenteric artery blood flow (SMABF) and muscle sympathetic nerve activity (MSNA) were recorded continuously during early tilt, presyncope and recovery. We used pixel-weighting to calculate average velocity from the pulsed Doppler velocity envelope.During baseline and early tilt, resistance to mesenteric blood flow was lower in the VVS group: 0.30 ± 0.02 to 0.30 ± 0.02 mmHg/ml/min versus controls 0.30 ± 0.03 to 0.38 ± 0.04 mmHg/ml/min (p = 0.05). During presyncope, as blood pressure and stroke volume gradually fell, SMABF was higher in the VVS group, falling from 370 ± 46 to 248 ± 35 ml/min, versus controls, falling from 342 ± 51 to 233 ± 19 (p = 0.03). At this time, MSNA was lower in the VVS group than controls: 39 ± 4 to 34 ± 3 bursts/min versus 45 ± 2 to 48 ± 3 (p = 0.001).During presyncope, increased splanchnic blood flow may pool more blood in capacitance vessels resulting in decreased venous return and cardiac output. This may be secondary to decreased vasoconstrictor sympathetic activity.Results: Vasovagal syncope is thought to be mediated by a progressive fall in cardiac output secondary to venous pooling of blood in the splanchnic circulation. How and when this occurs before syncope has not been determined.A total of 20 patients who became hypotensive during head-up tilt (age 40.9 ± 3.4 years; 10 females) were divided into two groups—the glyceryl trinitrate (GTN) group (n = 12) and the vasovagal syncope (VVS) group (n = 8) – on the basis of whether or not nitroglycerine provocation was required. They were compared with a control group (age 38.6 ± 3.3; 8 females; n = 13). Hemodynamics, including superior mesenteric artery blood flow (SMABF) and muscle sympathetic nerve activity (MSNA) were recorded continuously during early tilt, presyncope and recovery. We used pixel-weighting to calculate average velocity from the pulsed Doppler velocity envelope.During baseline and early tilt, resistance to mesenteric blood flow was lower in the VVS group: 0.30 ± 0.02 to 0.30 ± 0.02 mmHg/ml/min versus controls 0.30 ± 0.03 to 0.38 ± 0.04 mmHg/ml/min (p = 0.05). During presyncope, as blood pressure and stroke volume gradually fell, SMABF was higher in the VVS group, falling from 370 ± 46 to 248 ± 35 ml/min, versus controls, falling from 342 ± 51 to 233 ± 19 (p = 0.03). At this time, MSNA was lower in the VVS group than controls: 39 ± 4 to 34 ± 3 bursts/min versus 45 ± 2 to 48 ± 3 (p = 0.001).During presyncope, increased splanchnic blood flow may pool more blood in capacitance vessels resulting in decreased venous return and cardiac output. This may be secondary to decreased vasoconstrictor sympathetic activity.Conclusion: Vasovagal syncope is thought to be mediated by a progressive fall in cardiac output secondary to venous pooling of blood in the splanchnic circulation. How and when this occurs before syncope has not been determined.A total of 20 patients who became hypotensive during head-up tilt (age 40.9 ± 3.4 years; 10 females) were divided into two groups—the glyceryl trinitrate (GTN) group (n = 12) and the vasovagal syncope (VVS) group (n = 8) – on the basis of whether or not nitroglycerine provocation was required. They were compared with a control group (age 38.6 ± 3.3; 8 females; n = 13). Hemodynamics, including superior mesenteric artery blood flow (SMABF) and muscle sympathetic nerve activity (MSNA) were recorded continuously during early tilt, presyncope and recovery. We used pixel-weighting to calculate average velocity from the pulsed Doppler velocity envelope.During baseline and early tilt, resistance to mesenteric blood flow was lower in the VVS group: 0.30 ± 0.02 to 0.30 ± 0.02 mmHg/ml/min versus controls 0.30 ± 0.03 to 0.38 ± 0.04 mmHg/ml/min (p = 0.05). During presyncope, as blood pressure and stroke volume gradually fell, SMABF was higher in the VVS group, falling from 370 ± 46 to 248 ± 35 ml/min, versus controls, falling from 342 ± 51 to 233 ± 19 (p = 0.03). At this time, MSNA was lower in the VVS group than controls: 39 ± 4 to 34 ± 3 bursts/min versus 45 ± 2 to 48 ± 3 (p = 0.001).During presyncope, increased splanchnic blood flow may pool more blood in capacitance vessels resulting in decreased venous return and cardiac output. This may be secondary to decreased vasoconstrictor sympathetic activity. [ABSTRACT FROM AUTHOR]

Purpose: Enhanced external counterpulsation (EECP) is a recovery strategy whose use has increased in recent years owing to the benefits observed in the clinical setting in some cardiovascular diseases (ie, improvement of cardiovascular function). However, its claimed effectiveness for the enhancement of exercise recovery has not been analyzed in athletes. The aim of this study was to determine the effectiveness of EECP on short-term recovery after a fatiguing exercise bout. Methods: Twelve elite junior triathletes (16 [2] y) participated in this crossover counterbalanced study. After a high-intensity interval training session (6 bouts of 3-min duration at maximal intensity interspersed with 3-min rest periods), participants were assigned to recover during 30 min with EECP (80 mm Hg) or sham (0 mm Hg). Measures of recovery included performance (jump height and mean power during an 8-min time trial), metabolic (blood lactate concentration at several time points), autonomic (heart-rate variability at several time points), and subjective (rating of perceived exertion [RPE] and readiness to compete) outcomes. Results: There were no differences between EECP and sham in mean RPE or power output during the high-intensity interval training session, which elicited a significant performance impairment, vagal withdrawal, and increased blood lactate and RPE in both EECP and sham conditions (all P <.05). No significant differences were found in performance, metabolic, or subjective outcomes between conditions at any time point. A significantly lower high-frequency power (P <.05, effect size = 1.06), a marker of parasympathetic activity, was observed with EECP at the end of the recovery phase. Conclusion: EECP did not enhance short-term recovery after a high-intensity interval training session in healthy, highly trained individuals. [ABSTRACT FROM AUTHOR]