Tissue Vessels Research Articles

Relato de caso de infarto esplênico em uma criança com atresia biliar

This case report is intended to describe a rare case of splenic infarction (SI) associated with biliary atresia, which contributed to the worsening of the prognosis. In this case study, a boy diagnosed with biliary atresia underwent the Kasai procedure at the age of 3 months. The patient presented an intense abdominal pain, ascites and fever at the age of 6 years. A computed tomography (CT) scan showed enlargement of the spleen and an image suggestive of SI. The symptoms improved with the administration of antibiotics, analgesics, while ascites decreased with the use of diuretics. Liver transplantation was indicated. SI is an extremely rare event characterized by vessel occlusion, parenchymal ischemia and tissue necrosis. The symptoms are non-specific and may be confounding factors with other causes of acute abdominal pain. Splenomegaly-inducing diseases may be a risk factor. There are few case reports of SI and cirrhosis of different etiologies in childhood. Abdominal CT scan with intravenous contrast is the imaging modality of choice and the treatment ranges from supportive care to splenectomy. Despite being a rare condition, its knowledge is extremely important, as it allows early clinical suspicion, with immediate institution of treatment, which may interfere with the prognosis.

RELATO DE CASO DE INFARTO ESPLÊNICO EM UMA CRIANÇA COM ATRESIA BILIAR

This case report is intended to describe a rare case of splenic infarction (SI) associated with biliary atresia, which contributed to the worsening of the prognosis. In this case study, a boy diagnosed with biliary atresia underwent the Kasai procedure at the age of 3 months. The patient presented an intense abdominal pain, ascites and fever at the age of 6 years. A computed tomography (CT) scan showed enlargement of the spleen and an image suggestive of SI. The symptoms improved with the administration of antibiotics, analgesics, while ascites decreased with the use of diuretics. Liver transplantation was indicated. SI is an extremely rare event characterized by vessel occlusion, parenchymal ischemia and tissue necrosis. The symptoms are non-specific and may be confounding factors with other causes of acute abdominal pain. Splenomegaly-inducing diseases may be a risk factor. There are few case reports of SI and cirrhosis of different etiologies in childhood. Abdominal CT scan with intravenous contrast is the imaging modality of choice and the treatment ranges from supportive care to splenectomy. Despite being a rare condition, its knowledge is extremely important, as it allows early clinical suspicion, with immediate institution of treatment, which may interfere with the prognosis.

Preclinical in vivo assessment of a cell-free multi-layered scaffold prepared by 3D printing and electrospinning for small-diameter blood vessel tissue engineering in a canine model.

Tissue-engineered vascular grafts (TEVGs) are promising alternatives to existing prosthetic grafts. The objective of this study is to evaluate the clinical feasibility of a novel multi-layered small-diameter vascular graft that has a hierarchical structure. Vascular grafts with elaborately designed composition and architecture were prepared by 3D printing and electrospinning and were implanted into the femoral artery of 5 dogs. The patency of the grafts was assessed using Doppler ultrasonography. After 6 months, the grafts were retrieved and histological and SEM examinations were conducted. During implantation, the grafts exhibited resistance to kinking and no blood seepage thanks to the helical structure of the innermost and outermost layers. The grafts showed a high patency rate and remodelling ability. At 6 months post-implantation, the lumen was endothelialized and middle layers were regenerated by infiltration of smooth muscle cells (SMCs) and deposition of extracellular matrix (ECM). These results suggest that the multi-layered vascular graft may be a promising candidate for small-diameter blood vessel tissue engineering in clinical practice.

Optimal combinations of fluorescent vessel labeling and tissue clearing methods for three-dimensional visualization of vasculature.

Visualization of intact vasculatures is crucial to understanding the pathogeneses of different neurological and vascular diseases. Although various fluorescent vessel labeling methods have been used in combination with tissue clearing for three-dimensional (3D) visualization of different vascular networks, little has been done to quantify the labeling effect of each vessel labeling routine, as well as their applicability alongside various clearing protocols, making it difficult to select an optimal combination for finely constructing different vasculatures. Therefore, it is necessary to systematically assess the overall performance of these common vessel labeling methods combined with different tissue-clearing protocols. A comprehensive evaluation of the labeling quality of various vessel labeling routines in different organs, as well as their applicability alongside various clearing protocols, were performed to find the optimal combinations for 3D reconstruction of vascular networks with high quality. Four commonly-used vessel labeling techniques and six typical tissue optical clearing approaches were selected as candidates for the systematic evaluation. The vessel labeling efficiency, vessel labeling patterns, and compatibility of each vessel labeling method with different tissue-clearing protocols were quantitatively evaluated and compared. Based on the comprehensive evaluation results, the optimal combinations were selected for 3D reconstructions of vascular networks in several organs, including mouse brain, liver, and kidney. This study provides valuable insight on selecting the proper pipelines for 3D visualization of vascular networks, which may facilitate understanding of the underlying mechanisms of various neurovascular diseases.

Mycotic Thoracic Aortic Aneurysm: Epidemiology, Pathophysiology, Diagnosis, and Management.

Mycotic thoracic aortic aneurysm (MTAA) is an aneurysm of the aorta caused by infection of the vessel tissue through microbial inoculation of the diseased aortic endothelium. It is most commonly caused by bacteria. Rarely, it can be caused by fungi. However, viral aortic aneurysm has never been reported. Depending on the area and time period investigated, the infections organism discovered may vary significantly. Little is known about the natural history of MTAA due to its rarity. It is not known if they follow the same pattern as other TAAs.However, it is unclear whether MTAA follows a similar clinical course. The combination of clinical presentation, laboratory results, and radiographic results are used to make the diagnosis of MTAA. Treatment of MTAA is complex since patients frequently present at a late stage, frequently with fulminant sepsis, as well as concomitant complications such as aneurysm rupture. While medical treatment, including antibiotics, is recommended, surgery is still the mainstay of management. Surgery to treat MTAA is complicated and carries a high risk of morbidity and mortality and includes both open repairs and endovascular ones. In this review, we explore the etiology, pathogenesis, clinical presentations, diagnostic modalities as well as treatment management available for MTAA.

Extracorporeal Perfusion of Vascularized Composite Tissues: The Bridging Role of an Emerging Technology in Reconstructive Microsurgery.

Complex defects with exposed critical structures after trauma or tumor resections are routinely reconstructed with free flaps. In the current practice of reconstructive microsurgery, the success rate at high-volume centers is above 95%. However, despite high success rates, free tissue transfer is not without challenges and limitations. The high degree of technical skill and resources needed to perform these lengthy procedures are not fulfilled at every institution globally. In some cases, the availability of recipient vessels can be limited due to vascular disease or prior treatments. Additionally, perioperative patient decompensation could affect outcomes, especially in complex multitrauma patients. Therefore, an improved approach is still needed to ensure reliable flap transfer even in the presence of unanticipated events and compromised recipient vasculature. Considering the major advancements over the past few decades, further improvement at this point requires a paradigm shifting approach. Machine perfusion, classically used in the preservation of solid organs, offers a wide variety of implications for vascularized composite tissues. An extracorporeal perfusion system (EPS), similar to that used during cardiopulmonary bypass, can be used to isolate the tissue via cannulation of the primary artery and vein and provide temporary support. The research on this topic1 can be furthered to enable clinical use of such technology in three distinct purposes (Fig. 1).Fig. 1.: Conceptual schematic of the potential clinical needs that an extracorporeal perfusion system could address. Machine perfusion support could serve three distinct purposes in reconstructive microsurgery: (1) bridge-to-anastomosis, (2) bridge-to-neovascularization for traditional flaps, and (3) bridge-to-neovascularization for bioengineered flaps. Even the uses for purposes 1 and 2 might be rarer occurrences; once the technology is established for purpose 3, its indications will continually expand to cover purposes 1 and 2. Created with BioRender.com.●Bridge-to-anastomosis: An EPS could be used to maintain support of the tissue until transplantation and successful anastomosis to mitigate ischemia/reperfusion injury. This purpose could support the tissues during delays between harvesting and anastomosis such as transportation of composite allografts, temporizing replants, or stabilization of decompensating patients.2,3 ●Bridge-to-neovascularization for traditional flaps: A portable/wearable EPS could be maintained following inset of the tissue over a wound bed and obviate the need to isolate and connect to recipient vessels. Extracorporeal support would continue until sufficient vessel ingrowth and tissue integration has occurred and can be weaned once the neovascularized network itself can provide full tissue support. The basic feasibility of the bridge-to-neovascularization approach in a vessel depleted wound was demonstrated in a small case series and showed that less than 2 weeks of external perfusion could allow sufficient neovascularization.4 ●Bridge-to-neovascularization for bioengineered flaps: The third application has the broadest implications for clinical impact and the field of bioengineered vascularized composite tissues. Currently, although there are limited studies, a major obstacle in engineered vascular networks is thrombosis.5 An EPS would be crucial to ensure successful transfer of engineered constructs with the benefit of closed-system isolated drug delivery (eg, heparin, vasodilatory agents) and conditioned perfusate (eg, platelet depletion) to prevent intravascular thrombosis. Similarly, this closed circuit could be used for delivery of growth factors to induce angiogenesis and facilitate integration of the transferred tissue. In summary, an EPS would address immediate and future problems in complex soft-tissue reconstruction. Recent advancements in the machine perfusion field and its integration with reconstructive microsurgery could open doors for a novel subspecialty. The challenging scenario of extensive tissue loss could be managed without the need for microsurgery using a compact perfusion system. DISCLOSURE The authors have no financial interest to declare in relation to the content of this article.

Sensors-based monitoring and treatment approaches for in-stent restenosis.

Cardiovascular disease (CVD) can progressively narrow arteries due to plaque accumulation on the inner walls of the blood vessels, which results in an obstructed blood flow, leading to heart attack, stroke, and even death if the obstruction is severe. A popular treatment for the disease is to use an intravascular mechanical device called the stent to achieve an immediate restoration of blood flow. However, the physical stimulation induced by the stent expansion can cause inflammation of the vessel tissue. As one of the most common post-stenting complications, re-narrowing of the vessel is the main pathology that leads to in-stent restenosis (ISR), induced by the excess growth of the tissue over the deployed stent. The ISR is widely recognized as a significant cause of death globally if early symptoms are not detected. Hence, monitoring and early diagnosis indeed matter when it comes to treatment. The latest technologies for monitoring and treatments of ISR were reviewed in this work, and the potential issues and suggestions related to the reported technologies were presented. The target of this review aims to positively prompt researchers to develop an advanced stent system in terms of its electromechanical performance, size, functional feature, feasibility, and reliability.

Melatonin Improves Ischemia-Induced Circulation Recovery Impairment in Mice with Streptozotocin-Induced Diabetes by Improving the Endothelial Progenitor Cells Functioning.

Patients with diabetes mellitus tend to develop ischemia-related complications and have compromised endothelial progenitor cell (EPC) function. Melatonin protects against ischemic injury, possibly via EPC modulation. We investigated whether melatonin pretreatment could restore EPC function impairment and improve circulation recovery in a diabetic critical limb ischemia mouse model. Under 25 mM high-glucose medium in vitro, EPC proliferation, nitric oxide production, tube formation, and endothelial nitric oxide synthase (eNOS) phosphorylation were significantly suppressed. Hyperglycemia promoted EPC senescence and apoptosis as well as increased reactive oxygen species (ROS) production. Melatonin treatment reversed the harmful effects of hyperglycemia on EPC through adenosine monophosphate–activated protein kinase-related mechanisms to increase eNOS phosphorylation and heme oxygenase-1 expression. In an in-vivo study, after a 4-week surgical induction of hindlimb ischemia, mice with streptozotocin (STZ)-induced diabetes showed significant reductions in new vessel formation, tissue reperfusion, and EPC mobilization in ischemic hindlimbs compared to non-diabetic mice. Mice with STZ-induced diabetes that received melatonin treatment (10 mg/kg/day, intraperitoneal) had significantly improved blood perfusion ratios of ischemic to non-ischemic limb, EPC mobilization, and densities of capillaries. In addition, a murine bone marrow transplantation model to support these findings demonstrated that melatonin stimulated bone marrow-originated EPCs to differentiate into vascular endothelial cells in femoral ligation-induced ischemic muscles. In summary, this study suggests that melatonin treatment augments EPC function along with neovascularization in response to ischemia in diabetic mice. We illustrated the protective effects of melatonin on EPC H2O2 production, senescence, and migration through melatonin receptors and modulating eNOS, AMPK, and HO-1 activities at the cellular level. Thus, melatonin might be used to treat the impairment of EPC mobilization and circulation recuperation in response to ischemic injury caused by chronic hyperglycemia. Additional studies are needed to elucidate the applicability of the results in humans.

Conformational Transition-Driven Self-Folding Hydrogel Based on Silk Fibroin and Gelatin for Tissue Engineering Applications.

Self-folding is a rapidly evolving method for converting flat objects into three-dimensional(3D) structures. However, because there are few materials with suitable properties, the application of self-foldingin tissue engineering has been hindered greatly. Herein, a novel self-folding hydrogel using conformational transition mechanism is developed by employing photocrosslinkable silk fibroin and gelatin composite hydrogel. It is hypothesized that differences in the amount of beta-sheet(β-sheet) formation between the upper and lower layers will supply additional folding stress and drive the self-folding behavior of a bilayer patch, which canimprove the mechanical properties and long-term stability of the self-folded structure. In this study, the impact of various proportions of β-sheets in composite hydrogels on their swelling, mechanics, and internal microstructures are investigated. Subsequently, the folding process parameters are optimized, and diffusion through the folded tubular structure is studied with a perfusion test. Finally, it is proven that the self-folding hydrogel system is cytocompatible and can be utilized to build a 3D coculture system of "endothelial cells-smooth muscle cells". These findings suggest that the self-folding hydrogel can be a promising candidate for applications in blood vessel tissue engineering and regenerative medicine.

Induced Wood-Inorganic Composites in Standing Trees via Slow-Release Drip

It is a novel idea to fabricate wood-inorganic composites by utilizing the transpiration of bionic trees to realize the self-assembly of inorganic precursors in wood formation. We selected a 10-year-old poplar and diffused the solvent or sol containing SiO2 precursor into the xylem via the slow-release drip method. In combination with the moisture in xylem, reactions such as hydrolysis, polycondensation and self-assembly were induced in order to form wood inorganic composites. It was found, through microscopic observation, that such inorganic substances were yellowish brown and widely existed in vessels, wood fibers and ray cells. For the new grown wood, the fiber–tissue ratio and cell wall thickness underwent an increase, while the vessel diameter and tissue ratio experienced a decline. Moreover, such change was related to the concentration of precursors. EDS analysis proved that the elemental composition of sediments in wood cells was C, O, Si, K and Ca. XPS confirmed that the newly formed wood contained silicon oxide, illustrating that the standing tree slow-release drip technology could induce wood to fabricate inorganic composites.

Endothelial mesenchymal transformation and relationship with vascular abnormalities

Environmental stress has a significant impact on the development of cardiovascular disease. This stress causes the production of free radicals, which in turn leads to the modification of endothelial cells. Vascular endothelial cells will acquire new phenotypes and gradually change their normal physiology during this process. Vascular malformations, atherosclerosis, transplanted arteriosclerosis, aneurysms, and other diseases will result from vessel tissue modification. Vascular changes can occur early in the pregnancy and result in congenital diseases. Hemangioma is a common vascular congenital disease caused by factors that influenced embryo development. Many clinical studies on the etiologies, physiopathology, and treatment of vascular diseases have been conducted. In reviewing these papers, we hoped to advance knowledge of the connection between vascular problems and endothelial mesenchymal transition.

Mechanical Testing of Artificial Vessels and Tissues for Photoplethysmography Phantoms.

Various studies have looked at the efficiency of artificial vessel and tissue networks in the study of photoplethysmography (PPG) in an effort to better understand the origin of various morphological features present in the signal. Whilst there are all reasonable attempts made to replicate geometrical features such as vessel depth, vessel wall thickness and diameter etc., not many studies have attempted to replicate the mechanical properties such as vessel elasticity and tissue compressibility. This study reports two methods for tissue mechanical testing for the analysis of vessel elasticity and tissue compressibility. A two-part polydimethylsiloxane (PDMS) was used as a base material for both tissue and vessel construction, and the properties altered by changing the curing component ratio. Tissue compression properties were investigated using an industrially calibrated materials testing device using the protocol from the ASTM 0575-91 testing method. Vessel elasticity was investigated using a custom method and apparatus to report vessel diameter and length change simultaneously. Tissue compressive properties proved reasonably easy to replicate through catalyst alteration, however the vessel elasticity properties were found to be higher than expected at all reasonable catalyst ratios. The property of hyper-elasticity was observed in the artificial vessels though, leading to the conclusion that alternative material recipes or construction methods may be needed to correctly replicate the expected mechanical characteristics. Clinical Relevance- The latest generation of health monitoring devices, especially those that are wearable and used widely by individuals wishing to monitor their health daily are becoming smarter and more sophisticated in their functionality. The majority of such devices use photoplethysmography (PPG) as their primary monitoring technique. Being able to replicate the PPG in a phantom allows the continued study and development of devices, and to improve their functionality without the continued need for extensive user-testing.

Study the pathogenicity of Providencia Vermicola in mice

P. vermicola is an opportunistic pathogen of human and animals. To estimate the pathogeneses of P.vermicola in mice infected orally and I/P with 1x108 CFU/ml).The histopathological changes at 24 hrs showed infiltration of inflammatory cells and apoptosis in hepatocytes in the liver, infiltration of inflammatory cells around a congested blood vessel and interstitial tissue of kidney; lung revealed congestion of blood vessels, infiltration of inflammatory cells and alveolar emphysema; intestine appeared infiltration of mononuclear cells in mucosa layer with hyperplasia of goblet cells. In mice infected I/P, the liver showed infiltration of inflammatory cells in a necrotic area with granulomatous lesion formation, the spleen showed depletion of white pulp. The kidney revealed dilatation of bowman’s space with vacuolation of glomeruli. The intestine appeared infiltration of inflammatory cells in mucosa and submucosa layers with hyperplasia of goblet cells, also, the lung showed infiltration of inflammatory cells in interalveolar septa and alveolar emphysema.

Vessel filtering and segmentation of coronary CT angiographic images.

Coronary artery segmentation in coronary computed tomography angiography (CTA) images plays a crucial role in diagnosing cardiovascular diseases. However, due to the complexity of coronary CTA images and coronary structure, it is difficult to automatically segment coronary arteries accurately and efficiently from numerous coronary CTA images. In this study, an automatic method based on symmetrical radiation filter (SRF) and D-means is presented. The SRF, which is applied to the three orthogonal planes, is designed to filter the suspicious vessel tissue according to the features of gradient changes on vascular boundaries to segment coronary arteries accurately and reduce computational cost. Additionally, the D-means local clustering is proposed to be embedded into vessel segmentation to eliminate noise impact in coronary CTA images. The results of the proposed method were compared against the manual delineations in 210 coronary CTA data sets. The average values of true positive, false positive, Jaccard measure, and Dice coefficient were [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text], respectively. Moreover, comparing the delineated data sets and public data sets showed that the proposed method is better than the related methods. The experimental results indicate that the proposed method can perform complete, robust, and accurate segmentation of coronary arteries with low computational cost. Therefore, the proposed method is proven effective in vessel segmentation of coronary CTA images without extensive training data and can meet clinical applications.

Fluid–structure interaction (FSI) simulation for studying the impact of atherosclerosis on hemodynamics, arterial tissue remodeling, and initiation risk of intracranial aneurysms

The biomechanical and hemodynamic effects of atherosclerosis on the initiation of intracranial aneurysms (IA) are not yet clearly discovered. Also, studies for the observation of hemodynamic variation due to atherosclerotic stenosis and its impact on arterial remodeling and aneurysm genesis remain a controversial field of vascular engineering. The majority of studies performed are relevant to computational fluid dynamic (CFD) simulations. CFD studies are limited in consideration of blood and arterial tissue interactions. In this work, the interaction of the blood and vessel tissue because of atherosclerotic occlusions is studied by developing a fluid and structure interaction (FSI) analysis for the first time. The FSI presents a semi-realistic simulation environment to observe how the blood and vessels' structural interactions can increase the accuracy of the biomechanical study results. In the first step, many different intracranial vessels are modeled for an investigation of the biomechanical and hemodynamic effects of atherosclerosis in arterial tissue remodeling. Three physiological conditions of an intact artery, the artery with intracranial atherosclerosis (ICAS), and an atherosclerotic aneurysm (ACA) are employed in the models with required assumptions. Finally, the obtained outputs are studied with comparative and statistical analyses according to the intact model in a normal physiological condition. The results show that existing occlusions in the cross-sectional area of the arteries play a determinative role in changing the hemodynamic behavior of the arterial segments. The undesirable variations in blood velocity and pressure throughout the vessels increase the risk of arterial tissue remodeling and aneurysm formation.

Unveiling the Role of DNA Methylation in Vascular CACNA1C Tissue-Specific Expression.

ObjectiveCalcium voltage-gated channel subunit alpha1 C (CACNA1C) plays a critical role in many vascular physiological and pathological processes. Determining its tissue-specific expression pattern and clarifying the underlying molecular mechanisms are necessary and meaningful.MethodsWe selected several representative vessels from normal male Sprague-Dawley rats. Vessel tissue or primary vascular smooth muscle cells were isolated for vascular function, electrophysiology, gene expression and promoter methylation studies.ResultsWe found CACNA1C had tissue-specific expressions in vessels. The specific manifestations were as follows: CACNA1C expression was highest in thoracic aorta, second lowest in middle cerebral and pulmonary artery, and lowest in mesenteric artery. Excitingly, an opposing trend was observed between CACNA1C expression and its promoter methylation.ConclusionsThis study was the first report to indicate that DNA methylation could be involved in regulating CACNA1C tissue-specific expressions and vasoconstriction function in vascular system. This study not only provided more information for further understanding the physiological characteristics of vascular CACNA1C expressions, also strengthened the idea that DNA methylation plays important roles in regulating vascular smooth muscle cells function and the consequent occurrence of vascular diseases.

Diabetic Wound Healing in IL-1β expression by Nano Herbal of Zanthoxylum acanthopodium and Rhodomyrtus tomentosa

Wounds of diabetic patients cause damage to skin tissue for a long time. Increased glucose levels affect angiogenesis which triggers the wound to heal. This study was to determine IL-1β expression in diabetic wound healing after being given nano herbal of Zanthoxylum acanthopodium and Rhodomyrtus tomentosa. This study consisted of 4 treatment groups. K1: negative control, K2: MEBO, K3: Nano herbal of andaliman fruits (100mg/kg BW), and K4: Nano herbal of haramonting leaves (100mg/kg BW) on days 0, 4, 8, 12, and the 16th. The tissue was prepared on paraffin blocks and given Immunohistochemistry staining. Results showed that there was a significant difference between all groups (P <0.001) in IL-1β expression. Histologically in wound healing, the granulation tissue of blood vessels is dominated by extensive fibroblasts and collagen. The epithelium has covered the wound that occurred on the skin. This suggests that some of the compounds contained in the nano herbal haramonting and andaliman can stimulate cell division and growth to form scar tissue. In conclusion, epithelium covered the wound in MEBO treatment, showing that the histology of the skin tissue was almost the same as that of nano herbal andaliman and haramonting. Therefore Nano herbal andaliman and haramonting can be developed into herbs that can be used to treat wounds in diabetics.

Nanosized Fat Emulsion Injection Modulating Local Microenvironment Promotes Angiogenesis in Chronic Wound Healing

AbstractThe current treatment for chronic diabetic wounds is costly for patients and society. The proinflammatory state and impaired vascular condition are the main factors that hamper diabetic wound healing. In this study, fat emulsion (FE), a nanosized product clinically used to provide nutrition and energy to patients through vein injection, is evaluated for its diabetic wound healing capability for the first time. The nanosized FE is mixed with methacrylated hyaluronic acid (HA–MA) hydrogel to form an anti‐inflammatory and angiogenic FE/HA–MA hybrid hydrogel dressing to accelerate the diabetic wound closure. Results of RT‐qPCR analysis and ELISA demonstrate that the FE exerts excellent anti‐inflammatory effects by significantly downregulating the expression of proinflammatory cytokines tumor necrosis factor‐α (TNF‐α) and interleukin‐1β (IL‐1β), both in vitro and in vivo. The endothelial tube formation and scratch assays reveal that the FE promotes angiogenesis and cell migration, respectively, by releasing vascular endothelial growth factor A. The in vivo diabetic wound mouse model confirms an increased blood vessel density, healing rate, tissue epithelialization, and collagen deposition in the FE/HA–MA hybrid hydrogel dressing group compared to the control group. These findings may provide a promising and economic product and strategy for diabetic wound treatment in the clinic.

Numerical solution and mathematical modelling of mass transport from medicated stent

Restenosis in arteries is a major problem which can be controlled by using medicated stents. The controlled drug transport from medicated stents has a great effect in decreasing restenosis in arteries. Drug is coated on stents to keep away from the re-narrowing of the artery wall. This device has an advantage of a flexible time delivery of a curative drug to the adjoining blood vessel tissues. The aim of this study is to formulate a mathematical model which describe the process of drug transport from arterial wall and medicated stent. For this purpose, a 3D model is investigated to measure the impact of mass transport from drug eluting stent. The blood flow is modelled by dimensionless Navier stokes equations and the concentration of drug is driven by dimensionless’ convection diffusion equation. The effect of diffusive and advective forces are discovered and these forces can be used to control the drug mass transport. Moreover, the effect of dimensionless parameters such as Peclet number porosity k and on mass transport from medicated stent and tissue layers is investigated. Characteristic Based Split Galerkin (CBSG) technique is applied to solve the dimensionless equations. In the application of stent-based drug delivery, the governing equations in this exploration give the premise of a plan for examining and computing mass transport in medicated stent and artery wall. The numerical results support to offer a good insight into the possible impacts of various parameters.

Thermal lagging effect on heat transport within living biological tissues

Thermal lagging effect on heat transport within living biological tissues is explored in the context of different relaxation mechanisms. The governing equations of temperature rooted the delay effect between heat flux and temperature gradient, as well as non-equilibrium effect between blood vessel and peripheral tissues, are constructed separately via the classic dual-phase lag model (DPL) and generalized dual-phase lag model (GDPL). An analytical procedure based on the Laplace transform technique and its limit theorem is then proposed. The expressions and effective values of phase lags rooted different effect have been derived and further estimated. On this basis, the temperature response of a biological tissue with its boundary exposed to a pulse heat flux is analyzed. The detailed parametric study has been conducted to explore the dependence of these phase lags on tissue structures and their effect on heat transport properties. The results highlight the contributions of the delay effect and non-equilibrium effect in temperature prediction and state that the delay effect is dominated for a larger tissue size. Meanwhile a significant difference has also been observed with the boundary conditions that obey different thermal conduction mechanism.