Analysis Of Blood Flow Research Articles

Soret Effect on MHD Casson Fluid over an Accelerated Plate with the Help of Constant Proportional Caputo Fractional Derivative.

Non-Newtonian fluid flow is significant in engineering and biomedical applications such as thermal exchangers, electrical cooling mechanisms, nuclear reactor cooling, drug delivery, blood flow analysis, and tissue engineering. The Caputo operator has emerged as a prevalent tool in fractional calculus, garnering widespread recognition. This research aims to introduce a novel derivative by merging the proportional and Caputo operators, resulting in the fractional operator known as the constant proportional Caputo. In order to demonstrate this newly defined operator's dynamic qualities, it was employed in the analysis of the unsteady Casson flow model. In addition, the current work shows an analytical analysis to determine the Soret effect on the fractionalized MHD Casson fluid over an oscillating vertical plate. Fractional partial differential equations (PDEs) are used to formulate the problem along with IBCs. The introduction of appropriate nondimensional variables converts the PDEs into dimensionless form. The precise solutions to the fractional governing PDEs are then determined by the Laplace transform method. Velocity, concentration, and temperature profiles; the impacts of the Prandtl number; fractional parameter β and γ; and Soret and Schmidt numbers are graphically depicted. The profiles of temperature, concentration, and velocity rise with rising time and fractional parameters. Interestingly, as the Casson flow parameter is higher, fluid velocity decreases closest to the plate but increases away from the plate. Tables showing the findings for the skin-friction coefficient, Sherwood, and Nusselt numbers for a range of flow-controlling parameter values are provided. Furthermore, an investigation is undertaken to compare fractionalized and ordinary velocity fields. The results suggest that the fractional model employing a constant proportional derivative exhibits a quicker decay than the model incorporating conventional Caputo and Caputo-Fabrizio operators.

Hemodynamic Insights into Abdominal Aortic Aneurysms: Bridging the Knowledge Gap for Improved Patient Care

Background: Abdominal aortic aneurysms (AAAs) present a formidable public health concern due to their propensity for localized, anomalous expansion of the abdominal aorta. These insidious dilations, often in their early stages, mask the life-threatening potential for rupture, which carries a grave prognosis. Understanding the hemodynamic intricacies governing AAAs is paramount for predicting aneurysmal growth and the imminent risk of rupture. Objective: Our extensive investigation delves into this complex hemodynamic environment intrinsic to AAAs, utilizing comprehensive numerical analyses of the physiological pulsatile blood flow and realistic boundary conditions to explore the multifaceted dynamics influencing aneurysm rupture risk. Our study introduces novel elements by integrating these parameters into the overall context of aneurysm pathophysiology, thus advancing our understanding of the intricate mechanics governing their evolution and rupture. Methods: Conservation of mass and momentum equations are used to model the blood flow in an AAAs, and these equations are solved using a finite volume-based ANSYS Fluent solver. Resistance pressure outlets following a three-element Windkessel model were imposed at each outlet to accurately model the blood flow and the AAAs’ shear stress. Results: Our results uncover elevated blood flow velocities within an aneurysm, suggesting an augmented risk of future rupture due to increased stress in the aneurysm wall. During the systole phase, high wall shear stress (WSS) was observed, typically associated with a lower risk of rupture, while a low oscillatory shear index (OSI) was noted, correlating with a decreased risk of aneurysm expansion. Conversely, during the diastole phase, low WSS and a high OSI were identified, potentially weakening the aneurysm wall, thereby promoting expansion and rupture. Conclusion: Our study underscores the indispensable role of computational fluid dynamic (CFD) techniques in the diagnostic, therapeutic, and monitoring realms of AAAs. This body of research significantly advances our understanding of aneurysm pathophysiology, thus offering pivotal insights into the intricate mechanics underpinning their progression and rupture, informing clinical interventions and enhancing patient care.

Hemodynamical behavior analysis of anemic, diabetic, and healthy blood flow in the carotid artery

The influence of blood rheology on hemodynamic parameters is investigated using Computational Fluid Dynamics on blood flow through the human carotid artery. We performed three-dimensional modeling and simulation to study blood flow through the carotid artery, which is divided into internal and exterior parts with a decreased radius. The blood flow was classified as basic pulsatile to simulate the human heart's rhythmic pulses. For hemodynamic modeling viscosity of the fluid, the Carreau model was utilized with four distinct blood instances: Anemic, diabetic, and two healthy blood types. The boundary conditions with Carreau viscosity were applied using the Ansys Fluent simulator, and the governing equations were solved using the finite volume technique. Different time steps were tested for their impact on wall deformation, strain rate, blood velocity, pressure, wall shear, and skin friction coefficient. The hemodynamical parameters were calculated using many cross-sectional planes along the artery. Finally, the impact of the four types of blood cases listed above was investigated, and we discovered that each blood case has a substantial impact on blood velocity, pressure, wall shear, and strain rate along the artery.

Computational analysis of patient-specific pulsatile blood flow: The influence of non-Newtonian models on wall shear stress assessment

Blood is a sophisticated biological fluid with components like erythrocytes that give it non-Newtonian behavior. Hemodynamic factors such as velocity magnitude, pressure, and wall shear stress descriptors are the most important factors in the development of atherosclerosis. The wall shear stress descriptors are regulated not only by flow geometry but also by blood rheological properties. In the current study, we carried out a numerical analysis of the non-Newtonian pulsatile blood flow while taking into account a patient-specific geometry and transient boundary conditions. Non-Newtonian blood flow is modeled using the four non-Newtonian models: the power-law model, the Carreau model, the Casson model, and the Quemada model, and compared with the Newtonian model. Streamline analysis vividly illustrates velocity patterns, revealing the presence of recirculation zones near sinus regions. The study suggests the significance of selecting appropriate viscosity models for accurate assessments, particularly in regions with low time-average wall shear stress values, such as those associated with atherosclerotic plaques. The differences in the time-averaged wall shear stress between the four non-Newtonian models were found to be the highest in the Quemada model. The study concluded that the non-Newtonian model is required when the focus is on the low-time-averaged wall shear stress area.

CT-derived Fractional Flow Reserve: How, When, and Where to use this Novel Cardiac Imaging Tool.

Fractional flow reserve computed tomography (FFRCT) is a novel imaging modality. It utilizes computational fluid dynamics analysis of coronary blood flow obtained from CCTA images to estimate the decrease in pressure across coronary stenosis during the maximum hyperemia. The FFRCT can serve as a valuable tool in the assessment of coronary artery disease (CAD). This non-invasive option can be used as an alternative to the invasive fractional Flow Reserve (FFR) evaluation, which is presently considered the gold standard for evaluating the physiological significance of coronary stenoses. It can help in several clinical situations, including Assessment of Acute and stable chest pain, virtual planning for coronary stenting, and treatment decision-making. Although FFRCT has demonstrated potential clinical applications as a non-invasive imaging technique, it is also crucial to acknowledge its limitations in clinical practice. As a result, it is imperative to meticulously evaluate the advantages and drawbacks of FFRCT individually and contemplate its application in combination with other diagnostic examinations and clinical data.

Quantitative analysis of systemic perfusion and cerebral blood flow in the modeling of aging and orthostatic hypotension.

Introduction: Orthostatic hypotension (OH) is common among the older population. The mechanism hypothesized by OH as a risk factor for cognitive decline and dementia is repeated transient cerebral blood flow deficiency. However, to our knowledge, quantitative evaluation of cardiac output and cerebral blood flow due to acute blood pressure changes resulting from postural changes is rare. Methods: We report a new fluid-structure interaction model to analyze the quantitative relationship of cerebral blood flow during OH episodes. A device was designed to simulate the aging of blood vessels. Results and Discussion: The results showed that OH was associated with decreased transient cerebral blood flow. With the arterial aging, lesions, the reduction in cerebral blood flow is accelerated. These findings suggest that systolic blood pressure regulation is more strongly associated with cerebral blood flow than diastolic blood pressure, and that more severe OH carries a greater risk of dementia. The model containing multiple risk factors could apply to analyze and predict for individual patients. This study could explain the hypothesis that transient cerebral blood flow deficiency in recurrent OH is associated with cognitive decline and dementia.

Neuregulin-1, a member of the epidermal growth factor family, mitigates STING-mediated pyroptosis and necroptosis in ischaemic flaps

Abstract Background Ensuring the survival of the distal end of a random flap during hypoperfusion (ischaemia) is difficult in clinical practice. Effective prevention of programmed cell death is a potential strategy for inhibiting ischaemic flap necrosis. The activation of stimulator of interferon genes (STING) pathway promotes inflammation and leads to cell death. The epidermal growth factor family member neuregulin-1 (NRG1) reduces cell death by activating the protein kinase B (AKT) signalling pathway. Moreover, AKT signalling negatively regulates STING activity. We aimed to verify the efficacy of NRG1 injection in protecting against flap necrosis. Additionally, we investigated whether NRG1 effectively enhances ischemic flap survival by inhibiting pyroptosis and necroptosis through STING suppression. Methods A random-pattern skin flap model was generated on the backs of C57BL/6 mice. The skin flap survival area was determined. The blood supply and vascular network of the flap was assessed by laser Doppler blood flow analysis. Cluster of differentiation 34 immunohistochemistry (IHC) and haematoxylin and eosin (H&E) staining of the flap sections revealed microvessels. Transcriptome sequencing analysis revealed the mechanism by which NRG1 promotes the survival of ischaemic flaps. The levels of angiogenesis, oxidative stress, necroptosis, pyroptosis and indicators associated with signalling pathways in flaps were examined by IHC, immunofluorescence and Western blotting. Packaging adeno-associated virus (AAV) was used to activate STING in flaps. Results NRG1 promoted the survival of ischaemic flaps. An increased subcutaneous vascular network and neovascularization were found in ischaemic flaps after the application of NRG1. Transcriptomic gene ontology enrichment analysis and protein level detection indicated that necroptosis, pyroptosis and STING activity were reduced in the NRG1 group. The phosphorylation of AKT and forkhead box O3a (FOXO3a) were increased after NRG1 treatment. The increased expression of STING in flaps induced by AAV reversed the therapeutic effect of NRG1. The ability of NRG1 to phosphorylate AKT-FOXO3a, inhibit STING and promote flap survival was abolished after the application of the AKT inhibitor MK2206. Conclusions NRG1 inhibits pyroptosis and necroptosis by activating the AKT-FOXO3a signalling pathway to suppress STING activation and promote ischaemic flap survival.

CFD Analysis of Pulsatile Non-Newtonian Blood Flow in a Multi-Staged Stenosed Bifurcated Carotid Artery

Accumulation of plaque on the arterial walls leads to a cardiovascular condition known as Atherosclerosis. This leads to lumen stenosis, and when it occurs in the carotid artery, it can impede the blood-flow to the face, brain, and neck, potentially leading to a stroke. The aim of this paper is to provide a comprehensive study of the carotid artery under multiple stenosed conditions using Computational Fluid Dynamics. In this study, blood has been considered to be a non-Newtonian fluid exhibiting pulsatile flow based upon the Carreau model and a two-dimensional bifurcated human carotid artery has been modelled. The Navier-Stokes equations-based FVM (Finite Volume Method) is used to analyze the flow inside the artery, while RANS k-ω SST turbulence model has been applied in the analysis of parameters of blood under stenosed conditions. Four models based on different stages of stenosis (0%; 25%; 50% and 75%) have been developed with simulations run on Ansys to find the effects under stenosis. For all the simulations, 65:35 flow division has been used, indicating that 65% of the total blood flows through the Internal Carotid Artery and 35% flows through the External Carotid Artery. Velocity and pressure contour, velocity distribution on the modelled plane and wall shear stress on arterial walls are the primary parameters studied at varying timescales of a cardiac cycle. As the stenosis stage increases, the flow separation can be predicted with higher accuracy. With the help of these parameters, one can build and design better treatment choices, such as designing of stents with different materials or adding of Ag-Au (Silver - Gold) nanoparticles in the blood to change the hemodynamics.

Quantitative analysis of myocardial blood flow in surgically revascularized and not revascularized myocardial segments. A pilot PET study.

To prospectively compare changes in myocardial blood flow (MBF) and myocardial flow reserve (MFR) in multivessel coronary artery disease (MVCAD) patients undergoing incomplete revascularization (IR) versus complete revascularization (CR) by coronary artery bypass grafting (CABG). Seven male patients (age 68 ± 9years) with MVCAD underwent myocardial perfusion PET/CT with [13N]ammonia before and at least 4months after CABG. Segmental resting and stress MBF as well as MFR were measured. Resting and during stress left ventricle ejection fraction (LVEF) were also calculated. Three patients (43%) underwent CR and four (57%) IR. Among 119 myocardial segments, 101 (85%) were revascularized, and 18 (15%) were not. After CABG, stress MBF (mL/min/gr) and MFR are significantly increased in all myocardial segments, with a greater increase in the revascularized segments (p = 0.013). In both groups, LVEF significantly decreased during stress at baseline PET (p = 0.04), but not after CABG. Stress MBF and MFR significantly improve after CABG in both revascularized and not directly revascularized myocardial segments. IR strategy may be considered in patients with high surgical risk for CR.

Navigating cardiovascular dynamics through mathematical modeling of arterial blood flow

Blood flow analysis plays an essential role in understanding cardiovascular health and disease. An accurate mathematical modeling is necessary in context of representation of arterial domains and blood flow to learn about the intricate blood dynamics. In this paper we concentrate on the mathematical representation of the geometry of the blood artery and find numerical solutions with mild to severe degree of stenosis. Blood dynamics has steady state, in-compressible and laminar nature. The shear thinning non-viscous effects of blood are assumed to obey Carreau model. Fluid flow is based on coupled Navier-Stokes equation in three dimensions and is simulated with finite volume approach over hexahedral elements. Application of a constant mass flow rate at the inlet of the artery results in a number of observations to analyze. It is found that with increasing the severity of stenosis, blood velocity becomes higher in stenotic region, pressure drop along the arterial domain is increased and shear stresses exerted by blood on walls of artery are increased.

Comparison of microvascular flow imaging and contrast-enhanced ultrasound for blood flow analysis of cervical lymph node lesions.

To compare the diagnostic value of microvascular flow imaging (MVFI) with that of contrast-enhanced ultrasound (CEUS) for the analysis of blood flow in benign and malignant cervical lymph nodes. As a prospective study, 95 cervical enlarged lymph nodes (43 benign and 52 malignant) were observed in 95 patients using conventional ultrasonography (including gray and Color Doppler Flow Imaging), CEUS, and MVFI. Two researchers evaluated vascular parameters of MVFI (vascular distribution, internal vascular features, vascular index) and CEUS (enhancement mode, enhancement type) and compared the diagnostic effects of MVFI and CEUS.All results were compared with pathological findings. There were significant differences in the vascular distribution and internal vascular features of benign and malignant lymph nodes on MVFI (P < 0.05). The vascular distribution of benign lymph nodes was mainly of the central and avascular types, the internal blood vessels were mostly normal, the vascular distribution of malignant lymph nodes was mainly mixed, the internal vessels were mainly tortuous and displaced. The optimal cut-off value of the benign and malignant lymph node vascular index (VI) was 15.55%, and the area under the receiver operating characteristic curve (AUC) of the VI was 0.876. There were also significant differences in the enhancement mode and types of benign and malignant lymph nodes in CEUS (P < 0.05). The benign lymph nodes showed centrifugal perfusion, and the enhancement types were mostly type I and type II. Most malignant lymph nodes showed centripetal or mixed perfusion, and the enhancement types were usually type III and type IV. The accuracy, sensitivity, and specificity of CEUS in the diagnosis of lymph node lesions were 84.2%, 84.6% and 83.7%, respectively, and the AUC was 0.845. The accuracy, sensitivity, and specificity of MVFI in the diagnosis of lymph node lesions were 85.3%, 84.6%, and 86.0%, respectively, and the AUC was 0.886. Both CEUS and MVFI are valuable in differentiating benign and malignant lesions of lymph nodes and have a similar diagnostic performance; however, MVFI is less invasive and simpler than CEUS. Therefore it is preferred for auxiliary examination of enlarged lymph nodes that are difficult to diagnose by conventional ultrasound.

Intraoperative Blood Flow Analysis of Free Flaps with Arteriovenous Loops for Autologous Microsurgical Reconstruction

Background: Arteriovenous (AV) loops help to overcome absent or poor-quality recipient vessels in highly complex microvascular free flap reconstruction cases. There are no studies on blood flow and perfusion patterns. The purpose of this study was to evaluate and compare intraoperative hemodynamic characteristics of AV loops followed by free tissue transfer for thoracic wall and lower extremity reconstruction. Methods: this prospective clinical study combined Transit-Time Flowmetry and microvascular Indocyanine Green Angiography for the assessment of blood flow volume, arterial vascular resistance and intrinsic transit time at the time of AV loop construction and on the day of free flap transfer. Results: A total of 11 patients underwent AV loop creation, of whom five required chest wall reconstruction and six required reconstruction of the lower extremities. In seven of these cases, the latissimus dorsi flap and in four cases the vertical rectus abdominis myocutaneous (VRAM) flap was used as a free flap. At the time of loop construction, the blood flow volume of AV loops was 466 ± 180 mL/min, which increased to 698 ± 464 mL/min on the day of free tissue transfer (p &gt; 0.1). After free flap anastomosis, the blood flow volume significantly decreased to 18.5 ± 8.3 mL/min (p &lt; 0.001). There was no significant difference in blood flow volume or arterial vascular resistance between latissimus dorsi and VRAM flaps, nor between thoracic wall and lower extremity reconstruction. However, a significant correlation between the flap weight and the blood flow volume, as well as to the arterial vascular resistance, was found (p &lt; 0.05). Conclusion: This is the first study to perform intraoperative blood flow and hemodynamic measurements of AV loops followed by free tissue transfer. Our results show hemodynamic differences and contribute to deeper understanding of the properties of AV loops for free flap reconstruction.

Multimodal real-time imaging with laser speckle contrast and fluorescent contrast

IntroductionLaser speckle contrast imaging (LSCI) can achieve real-time 2D perfusion maps non-invasively. However, LSCI is still difficult to use in general clinical applications because of movement sensitivity and limitations in blood flow analysis. To overcome this, fluorescence imaging (FI) is combined with LSCI using a light source with a wavelength of 785 nm in near-infrared (NIR) region and validates to visualize real-time blood perfusion. Materials and methodsThe system was performed using Intralipid and indocyanine green (ICG) in a flow phantom that has three tubes and controlled the flow rate in 0–150 μl/min range. First, real-time LSCI was monitored and measured the change in speckle contrast by reperfusion. Then, we visualized blood perfusion of a rabbit ear under the non-invasive condition by intravenous injection using a total of five different ICG concentration solutions from 128 μM to 3.22 mM. ResultsThe combined system achieved the performance of processing laser speckle images at about 37–38 fps, and we simultaneously confirmed the fluorescence of ICG and changes in speckle contrast due to intralipid as a light scatterer. In addition, we obtained real-time contrast variation and fluorescent images occurring in rabbit's blood perfusion. ConclusionsThe aim of this study is to provide a real-time diagnostic imaging system that can be used in general clinical applications. LSCI and FI are combined complementary for observing tissue perfusion using a single NIR light source. The combined system could achieve real-time visualization of blood perfusion non-invasively.

Analysis of blood and cerebrospinal fluid flows in preclinical AD. Preliminary results from ALFA+ cohort

AbstractBackgroundIntracranial cerebrospinal fluid (CSF) motion is driven by the wave pressure associated with arterial blood flow into the skull (Figure 1). Since one of the roles of CSF is the clearance of neural waste, it was investigated the relationship between blood and CSF flow parameters (as measured by magnetic resonance imaging [MRI]) and CSF Ab42/40 and ptau‐181 levels in the preclinical stages of Alzheimer’s disease (AD).MethodThree hundred sixty‐five subjects from the ALFA+ cohort underwent two MRI phase‐encoded velocity sequences (30 frames per cardiac cycle) to measure (1) blood flow in carotids below carotid bifurcation and (2) CSF flow through foramen magnum. The scanner’s Q‐flow tool was used to quantify stroke volume (volume per cardiac cycle), percent of vessel’s area increase and flow velocity increase, as a proxy for vessel elasticity and flow pulsatility, respectively. Associations between flow parameters and age, CSF Ab42/40 and ptau‐181 concentrations were sought, correcting for sex, age and time between lumbar puncture and MRI (P&lt;0.05).ResultOne hundred thirty‐two subjects were excluded because the scanning session was not completed, showed missing or outlier values or did not pass quality control (artifacts or unbalanced outwards‐inwards CSF flow measures), resulting in a final sample size of 233 participants (mean age [SD]: 60.8±4.5 years; male: n = 73 [31.3%]). Figure 2 shows the plots with the most significant relationships between flow parameters, CSF biomarkers, CSF volume and age. It was observed that a higher stroke volume in CSF flow was associated with lower Ab42/40 and higher ptau‐181 concentrations in CSF.ConclusionThese results indicate that, despite the role of CSF in waste clearance, the accumulation of amyloid and tau in the brain might be neither caused nor enhanced by a global deficit in CSF circulation. We hypothesize that a higher volume of CSF associated with age and high ptau‐181 levels and/or the loss of parenchyma elasticity might reduce the global intracranial compressibility, resulting in an enhanced response to pressure increase due to blood flow into the skull, which could explain the observed increase in CSF flow associated with the early stages of AD.

An efficient numerical scheme for solving the melting transportation of energy with time dependent Carreau nanofluid

The current work is categorized into the following formatBackground: Heat transfer controlling through therapy and blood flow has clinical importance in different levels of the human body. Biological faculties utilize blood in which iron oxide nanoparticles are incorporated for contrast agents and in the biomedical fields as they possess key and intrinsic characteristics, like low toxicity, capability of blood carrying nanoparticles, surface engineering and colloidal stability. This paper has a unique approach for analysis of blood flow containing nanoparticles with mathematical model of Carreau nanofluid. Furthermore, heat transport analysis has been provided by using the melting heat conditions and free convection.Carreau nanofluid for blood flow gives a set of partial differential equations (PDEs), which are handled by using the Keller Box scheme to obtain the numerical performances of the results. The obtained results are compared with Bvp4c, which is MATLAB built in program and found smooth agreement. The graphical plots and statistical tables have been provided for various dimensionless parameters to get the numerical simulations of the problem against velocity, temperature, and heat transfer Nusselt number. From the obtained results, the velocity and temperature of the fluid diminishes by the virtue of an amplification in unsteady parameter A. A positive variation in melting parameter M in the case of Prandtl number Pr and unsteady parameter A magnifies the heat transfer Nusselt number. This article shows the novelty in the sense that the effect of Tiwari and Das model accompanied with melting heat transfer phenomenon in the case of unsteady Carreau fluid has not investigated before in the available literature related to the Carreau fluid.

NUMERICAL SIMULATIONS OF BLOOD FLOW THROUGH LEFT VENTRICLE USING SPH AND FVM METHODS – A COMPARATIVE STUDY

This paper presents a comparative analysis of numerical simulations of blood flow through the left ventricle using SPH (LS-DYNA) and FVM (Ansys Fluent) solvers. Numerical simulations based on SPH and FVM methods can provide a more comprehensive understanding of cardiac blood flow patterns. In Fluent, left ventricle walls were modeled as boundary conditions with zero fluid velocity, while in the LS-DYNA software the walls were modeled with fixed particles. Boundary conditions were also prescribed on the appropriate regions (inlet, outlet, symmetry). In both programmes, inlet and outlet velocities were defined using table functions corresponding to the real cardiac cycle. For generating fluid flow in SPH, injection particles at mitral valve and deactivation planes at aortic semilunar valve were used. Numerical analysis results are given comparatively in both cases at the corresponding times. By comparing the results, it can be concluded that SPH can be efficiently used for the analysis of blood flow through the left ventricle. Although the modeling procedure, as well as the calculation itself, takes much longer to execute using SPH, this method offers possibilities such as studying FSI phenomena or tracking the movement of particles through the fluid domain.

A snake cathelicidin enhances transcription factor EB-mediated autophagy and alleviates ROS-induced pyroptosis after ischaemia-reperfusion injury of island skin flaps.

Ischaemia-reperfusion (I/R) injury is a major contributor to skin flap necrosis, which presents a challenge in achieving satisfactory therapeutic outcomes. Previous studies showed that cathelicidin-BF (BF-30) protects tissues from I/R injury. In this investigation, BF-30 was synthesized and its role and mechanism in promoting survival of I/R-injured skin flaps explored. Survival rate analysis and laser Doppler blood flow analysis were used to evaluate I/R-injured flap viability. Western blotting, immunofluorescence, TdT-mediated dUTP nick end labelling (TUNEL) and dihydroethidium were utilized to examine the levels of apoptosis, pyroptosis, oxidative stress, transcription factor EB (TFEB)-mediated autophagy and molecules related to the adenosine 5'-monophosphate-activated protein kinase (AMPK)-transient receptor potential mucolipin 1 (TRPML1)-calcineurin signalling pathway. The outcomes revealed that BF-30 enhanced I/R-injured island skin flap viability. Autophagy, oxidative stress, pyroptosis and apoptosis were related to the BF-30 capability to enhance I/R-injured flap survival. Improved autophagy flux and tolerance to oxidative stress promoted the inhibition of apoptosis and pyroptosis in vascular endothelial cells. Activation of TFEB increased autophagy and inhibited endothelial cell oxidative stress in I/R-injured flaps. A reduction in TFEB level led to a loss of the protective effect of BF-30, by reducing autophagy flux and increasing the accumulation of reactive oxygen species (ROS) in endothelial cells. Additionally, BF-30 modulated TFEB activity via the AMPK-TRPML1-calcineurin signalling pathway. BF-30 promotes I/R-injured skin flap survival by TFEB-mediated up-regulation of autophagy and inhibition of oxidative stress, which may have possible clinical applications.

Consequences of variable wall permeability and magnetic field on non-isothermal flow in converging/diverging tubes

The current article is devoted to the development of a theoretical model investigating heat transfer analysis of MHD blood flow through renal tubules. For this purpose, we consider the transport of Newtonian fluid inside a non-uniform tube whose lateral surface is kept at constant temperature. The walls of tube are considered to admit the variable permeation and the flow is actuated by an externally applied magnetic field. The solution of the problem is formulated analytically in terms of axial and radial velocities and temperature distribution under the presumption of lubrication approximation in the inertia free flow field. Implication of Darcy’s law for fluid seepage across the tubular membrane results in an ordinary differential equation having variable coefficients for the unknown pressure, which is successfully computed numerically using RK45 routine. Performance of velocity, pressure and temperature distributions has been investigated for various values of the physical parameters involving in the model. Moreover, flow rate behavior, fluid reabsorption and the leakage flux has been analyzed through graphs and tables. The characteristics of heat transfer in the flow field is also evaluated for various values of Brinkman number. A significant discovery reported in the results of present model reveals that the axial flow exhaustion and radial flow reversal are significantly influenced by the tube converging/diverging parameter and the Hartmann number as well. By employing a strong magnetic field, exhaustion and reversal phenomena in the flow field can be restrained up to a certain limit. Moreover, with an increasing wall permeability, there is a significant exhaustion of axial flow in a divergent tube and a prominent assistance takes place in the radial flow reversal for convergent tube. It is hoped that the present model will bear the potential to study flow in renal tubules and in hemodialyzer.

Diagnosis of the venous duct in fetuses of the early period of human ontogeny

To carry out an analysis of data from the world literature regarding the role of Doppler assessment of blood flow in the venous duct of the fetus in chromosomal abnormalities in the first trimester of pregnancy, as a marker – the spectral form of wave blood flow and its pulsation, which is generated by changes in the pressure and volume of blood to the heart of the fetus. Prenatal diagnosis of venous blood flow makes it possible to assess the state of the fetal cardiovascular system. Blood flow in the ductus venosus is an integrative indicator that reflects the formation of blood circulation of both the uteroplacental and placental-fetal components of gestational hemodynamics during physiological and complicated pregnancy. The performance of this test is 63%, and in combination with the assessment of the thickness of the clavicle – 89.1%. When reverse values of blood flow in the ductus venosus are detected in the phase of contraction of the atrium and dilated cervical space, it is necessary to carry out karyotyping to rule out chromosomal abnormalities. Dopplerography allows us to objectively assess the functioning state of the fetus during physiological and complicated pregnancy based on the study of the state of blood flow in the vessels of the placenta, in the middle cerebral artery, thoracic aorta, renal arteries, inferior vena cava and venous duct. The spectrum of venous blood flow reflects changes in volume and pressure in the atria during the cardiac cycle. With normal fetal development, blood flow in the venous duct has a pulsating character in the form of a unidirectional three-phase curve that corresponds to different periods of the cardiac cycle. The spectrum of normal blood flow in the venous duct in a healthy newborn has a biphasic curve, with the direction from the portal sinus to the inferior vena cava. During three weeks of regular examinations in most babies, obliteration of the venous duct occurs, and the ductus turns into a venous connection. Two-dimensional echocardiogram, color and pulsed dopplerography allow recording the waveforms of blood flow in several structures of the heart. Doppler analysis of blood flow in the venous duct is important to perform in fetuses of the first trimester, as it increases the sensitivity of the combined test in assessing the risk of chromosomal disorders. Assessment of blood flow in the ductus venosus provides an understanding of physiological and pathological processes in the fetal body and identifies fetuses that are prone to or at risk of disease.

Analysis of pulsatile blood flow through elliptical multi-stenosed inclined artery influenced by body acceleration

The effect of body acceleration on the pulsatile flow of blood through the elliptical artery having stenosis at the multiple positions of its wall is investigated in the current study. The artery is inclined at angle θ with horizontal, and blood is considered as Casson fluid. The mathematical model is processed into non-dimensional form and simplified using assumptions of mild stenosis. The analytical solution of mathematical equations is obtained in the elliptic bounded domain by employing the perturbation technique with Womersley frequency as a perturbation parameter and validated through case comparison with the previous study. The impacts of external acceleration, stenosis height, shape, gravitational acceleration, yield stress, and inclination angle on the flow velocity, flow rate, wall shear stress, and flow resistance are analyzed. It is found that body acceleration, gravitational acceleration, and inclination angle increase the flow rate and diminish the frictional resistance. The more significant yield stress and stenosis height enhance the flow resistance and reduce the flow rate. Moreover, fluid has higher velocity in the case of the non-symmetric shape of stenosis compared with the symmetric form.