Endothelial Lining Research Articles

Endothelial function and atrial fibrillation: A missing piece of the puzzle?

Endothelial dysfunction, a term used to describe both the physical damage and dysregulated physiology of this endothelial lining, is an increasingly recognized pathophysiological state shared by many cardiovascular diseases. Historically, the role of endothelial dysfunction in atrial fibrillation (AF) was thought to be limited to mediating atrial thromboembolism. However, there is emerging evidence that endothelial dysfunction both promotes and maintains atrial arrhythmic substrate, predicts adverse outcomes, and identifies patients at high risk of recurrence following cardioversion and ablation therapy. Treatments targeted at improving endothelial function also represent a promising new therapeutic paradigm in AF. This review summarizes the current understanding of endothelial function in AF.

In Situ Microscopy Studies of Infused Megakaryocytes: Implications in Thrombopoiesis

The questions of whether thrombopoiesis - the release of platelets from megakaryocytes - occurs both as megakaryocytes emerge from the intramedullar space or occurs as well in the pulmonary vascular bed remains unanswered. Studies by Lefrançais E, et al, (Nature, 2017) demonstrated by in situ microcopy that perhaps 50% of all platelet release in mice occurs from megakaryocytes released from the marrow and traveled to the lungs where they undergo thrombopoiesis over a 20- to 60-minute time-period. We examined whether CD34+-derived human megakaryocytes infused into immunocompromized NSG mice would also shed platelets in the lungs in a similar fashion. We differentiated CD34+-derived hematopoietic stem-progenitors for 12 days in culture using conditions previously described (Wang Y, et al., Blood 2015). We found that unlike platelet-like-particle (PLP) formation in in vitro cultures of CD34+ hematopoietic progenitor cell (HPC)-derived (CD34+) megakaryocytes, which undergo asynchronous shedding of the PLPs, that over 95% of infused CD34+ megakaryocytes shed their platelets within the first 40 minutes much as has been observed for endogenous murine megakaryocytes. The average number of cytoplasmic extensions per megakaryocytes was ~2.7, again very similar to what was seen with endogenous murine megakaryocytes. In contrast, CD34+ cells grown in culture into megakaryocytes for a shorter period of time of only 7 days, poorly shed any cytoplasmic fragments. We also studied human megakaryocytes grown from immortalized megakaryocyte progenitor cell lines (imMKCLs) from induced pluripotent stem cells (iPSCs) generated by the Eto laboratory and kindly provided by Dr. Koji Eto, Kyoto University). These cells were grown and differentiated into terminal megakaryocytes as described (Nakamura S, Cell Stem Cell, 2014) for 4 days in culture. These cells have been proposed to be useful for large-scale preparation of PLPs in vitro for clinical use in place of donor-derived platelets. The resultant infused human imMKCL-derived megakaryocytes also synchronously shed platelets, but only 50% of the infused cells shed their cytoplasm in contrast to >95% of CD34+ megakaryocytes. Moreover, cytoplasmic extensions were decreased to an average of ~1.1 per megakaryocyte. We had proposed that in vitro-generated megakaryocytes might be directly infused into patients in place of further manipulating the megakaryocytes to release functional platelets in vitro using a bioreactor. However, such megakaryocytes will likely be contaminated with a higher level of HPCs than anticipated from in vitro-prepared platelets, and concern exists that they may lead to unacceptable graft versus host complications. We, therefore, examined whether irradiating megakaryocytes as one strategy to eliminate this concern results in megakaryocytes that are still functional and found that megakaryocytes irradiated with up to 25 Gy retain platelet yield per infused megakaryocytes with the platelets having the same half-life. If irradiated and kept in culture, these megakaryocytes begin to shed platelets and undergo apoptosis notably by 24 hours. We also examined whether the pulmonary bed differs from other vascular beds, and infused CD34+ megakaryocytes both intravenously and intra-arterially in parallel studies and found that following intra-arterial infusion, megakaryocytes were mostly entrapped in various organs, but shed few platelets. Thus, our studies suggest that the pulmonary bed is unique for platelet shedding from entrapped megakaryocytes. Whether this is due to the structural organization of the pulmonary beds, its endothelial lining, its reverse exchange in oxygen, carbon dioxide and pH from other capillary beds or the mechanical forces of inhalation and exhalation that expand and contract the capillary cross-sectional area needs to be examined. Our studies show that infused human megakaryocytes synchronously release platelets over a 40-minute window and can do so even after being irradiated and that this occurs specifically in the lungs not only has potential clinical application, but also raises biological questions about what determines thrombopoiesis-readiness and what are the features of the pulmonary bed that allows this synchronous release. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Coadministration of Melatonin and Insulin Improves Diabetes-Induced Impairment of Rat Kidney Function

Introduction: The present study was designed to evaluate the therapeutic efficacy of melatonin and insulin coadministration in diabetes-induced renal injury in rats. Research Design and Methods: Diabetes was achieved by giving streptozotocin (15 mg/kg) for 6 consecutive days. The diabetic condition was confirmed by assessing the blood glucose level; animals having blood glucose levels above 250 mg were considered as diabetic. Following the confirmation, animals were randomly divided into different experimental groups, viz group I served as the control (CON), group II diabetic (D), group III D+melatonin (MEL), group IV D+insulin (INS), group V D+MEL+INS, group VI D+glibenclamide (GB), group VII CON+MEL, group VIII CON+INS, and group IX CON+GB. Following the completion of the experimental period, animals were sacrificed, blood was collected via a retro-orbital puncture, and kidneys were harvested. Diabetic rats exhibited a significant increment in blood glucose and biochemical indexes of renal injury (tubular disruption, swollen glomeruli with loss of glomerular spaces, and distortion of the endothelial lining) including augmented levels of serum creatinine, urea, uric acid, Na+, and K+, and inhibition/suppression of the activity of glutathione (GSH) peroxidase, GSH reductase, glucose-6-phosphate dehydrogenase, and GSH-S-transferase in the renal cortex. Results: By examining thiobarbiturate reactive substances, reduced GSH, superoxide dismutase activity, and catalase activity in the renal cortex of control and diabetic rats, it was documented that treatment with melatonin or insulin alone or in combination showed a significant ad integrum recovery of GSH-dependent antioxidative enzymatic activities. Melatonin and insulin coadministration caused greater reductions in circulating tumor necrosis factor-α, tumor growth factor-β1, interleukin (IL)-1β, and IL-6 levels in diabetic rats, whereas IL-10 levels increased, as compared to each treatment alone. Diabetic rats showed a significant increase in the expression of both MT1 and MT2 melatonin receptor genes. Melatonin or insulin treatment alone or in combination resulted in significant restoration of the relative expression of both melatonin receptors in the renal cortex. Conclusion: The coadministration of exogenous melatonin and insulin abolished many of the deleterious effects of type 1 diabetes on rat renal function.

Morphometric and genetic studies of the mechanisms of damage to the cardiovascular system in Kuzbass miners with dust lung pathology

Introduction. The combined impact of unfavorable factors of the production environment in miners leads to the development of associated pathology of the bronchopulmonary and cardiovascular systems, the predisposition to which depends on the individual susceptibility of the body. In this regard, it is important to comprehensively study the pathogenetic mechanisms underlying the formation and course of occupational and work-related diseases for a personalized approach to the diagnosis, prevention and therapy of this pathology. The purpose of this study was to study the mechanisms of damage to the cardiovascular system in miners with dust lung pathology on the basis of morphological and genetic studies. Materials and methods. For genetic studies, venous blood drawing was conducted in 190 Kuzbass miners. The main group included 126 miners of the main professions with the previously proven diagnosis "dust lung pathology", the comparison group consisted of 64 workers without a proven diagnosis working in similar sanitary and hygienic conditions. Morphometric studies were carried out using autopsy material obtained during 80 forensic medical examinations of miners in the Kemerovo region. All the miners were divided into 4 groups depending on their underground work experience. The control group was formed from 20 cases of forensic medical examinations of men who died in road accidents and did not have organ pathology according to the results of autopsies. Results. The study of the autopsy material revealed the presence of morphostructural changes in the vascular walls of the miners’ hearts in the form of hypertrophy of the smooth muscle cells of the medial layers, thickening of the endothelial lining, and the development of fibroplastic changes in the perivascular zones. These changes began to form from the first years of work in the underground conditions and progressed with increasing work experience contributing to the "recalibration" of the heart vessels with the formation of the lumen "obstruction". One of the mechanisms of endothelial damage in miners was a change in the expression of the EDN1 gene, which regulates the synthesis of endothelin-1. The risk and resistance genotypes of the development of dust lung pathology for the rs5370 polymorphism of the EDN1 gene were identified. Morphostructural rearrangement of the endothelium in the combination with its pathological activation contributed to the occurrence of endothelial dysfunction in miners. Conclusions. The conducted studies of the parameters of the vascular endothelium indicate its key role in the pathogenesis of bronchopulmonary and cardiovascular pathology in miners of the main professions. Getting into the body of workers, particles of coal-rock dust lead to morphostructural rearrangement of the cells of the endothelial layer and its pathological activation. The contribution of molecular and genetic mechanisms to the development of occupational lung pathology and associated diseases of the circulatory system in miners is revealed. Ethics. The studies were carried out in compliance with the ethical standards of the Bioethical Committee of the Research Institute for Complex Problems of Hygiene and Occupational Diseases, elaborated on the basis of the Helsinki Declaration of the World Medical Association "Ethical Principles for Conducting Human Scientific Medical Research" as amended in 2013 and the "Rules of Clinical Practice in the Russian Federation" approved by the Order of the Ministry of Health of the Russian Federation No. 266 dated 19.06.2003. All workers were informed about their participation in the molecular-genetic study and gave written consent to carry it out. The research of the dead miners was based on the secondary examination of blocks and ready-made histological micro-preparations of the material of the Bureau for Forensic Medical Expert Examination of the cities of Novokuznetsk, Osinniki, and Prokopyevsk. The study of pathomorphological material was carried out in accordance with the Federal Law of 21.11.2011, No. 323-FZ "On the Fundamentals of Health Protection of Citizens in the Russian Federation", in particular, with Article 67 "Carrying out pathological and anatomical autopsies", Federal Law of 12.01.1996, No. 8-FZ "On burial and funeral business" (Article 5, paragraphs 1, 2), as well as on the basis of the Order of the Ministry of Health of April 29, 1994, No. 82 "On the procedure for conducting pathological and anatomical autopsy" (Annex to the Order of the Ministry of Health and Medical Industry of 29.04.1994 No. 82), the Order of the Ministry of Health of Russia of 24.03.2016. No. 179n "On the rules for conducting pathological and anatomical examinations".

The Efficacy of Hydrodilatation for the Prevention of Vasospasm following Microsurgical Anastomosis.

Vasospasm is a major problem following microsurgical reconstruction which can result in the partial or complete loss of the flap tissue. The aim of this study was to investigate the efficiency of hydrodilatation for the prevention of vasospasm. Thirty male Wistar rats were used for this experimental study. Femoral arteries of were exposed, photographed, and transected. In group 1, group 2, and group 3 papaverine solution, hydrodilatation, and minimal mechanical dilatation (control group) was performed, respectively. The anastomosis was completed and the arteries were photographed again 10 minutes after completion of the anastomosis. Following 7-day period samples for transmission electron microscopy (TEM) and light microscopy were obtained. The mean vessel diameters prior to transection were 0.43, 0.45, and 0.52 mm in the papaverine, hydrodilatation, and control groups, respectively. The mean vessel diameter 10 minutes following the completion of anastomosis was 0.76, 0.75, and 0.51 mm in the papaverine, hydrodilatation, and control groups, respectively. Median score for papaverine group regarding histological parameters of regular endothelial lining and lumen, neutrophil infiltration, vascular congestion, and edema in tunica adventitia was 2, 3, 2, and 3 positive, respectively. Median score for the papaverine group regarding histological parameters of regular endothelial lining and lumen, neutrophil infiltration, vascular congestion, and edema in tunica adventitia was 3, 3, 3, and 3 positive, respectively. All the histological scores were negative in the control group. The difference between the control group and the experiment groups 1 and 2 was significant regarding all four histological parameters (p < 0.05). Hydrodilatation and papaverine application were both effective in preventing vasospasm following microsurgical intervention but papaverine caused slightly less damage to the endothelial lining and less edema in the tunica adventitia when compared with the hydrodilatation. Hydrodilatation group showed a vasodilatory effect that was statistically similar to that of papaverine, which has a proven efficacy.

CASE OF PERICARDIAL ANGIOSARCOMA IN A 42-YEAR-OLD MALE PRESENTING WITH CARDIAC TAMPONADE, PLEURAL EFFUSIONS, AND DYSPNEA ON THE PULMONARY SERVICE

TOPIC: Signs and Symptoms of Chest Diseases TYPE: Medical Student/Resident Case Reports INTRODUCTION: Angiosarcomas (AS) are rare, aggressive cancers that develop in the endothelial lining of lymph and blood vessels. A review by Chen et al (2020) describes an incidence of 2-3.5 per million. Due to their aggressive nature, they have very poor prognoses. The 5-year survival for all-comers with AS is estimated to be 35%. Cardiac sarcomas are the most common primary cardiac malignancy (Li et al, 2020). There are very few case reports of pericardial AS, as it is exceedingly rare. CASE PRESENTATION: A 42-year-old healthy male, with history of esophagitis and ADHD, presented to hospital with fatigue and dyspnea. He was hemodynamically unwell. Ultrasound revealed a pericardial effusion concerning for tamponade, pleural effusions and free fluid in the abdomen. CT scan demonstrated pathological mediastinal adenopathy and the working diagnosis was pericarditis. He underwent a pericardiocentesis, which was non-contributory. Bronchoscopy with nodal biopsy showed non-caseating granulomas. Cardiac MR ruled out sarcoidosis.He presented three months later with a moderate-sized pericardial effusion with early signs of tamponade. He was treated again with anti-inflammatories. A few months later, he presented with two-weeks of progressive dyspnea on exertion. Ultrasound demonstrated a moderate left pleural effusion, but no pericardial effusion. ECHO showed a "soft-tissue like echogenicity near the cardiac apex and right ventricle". Repeat Cardiac MR demonstrated severe thickening of the pericardium thought to be consistent with recurrent pericarditis. He shortly re-presented with rapidly accumulating pleural effusions and recurrent pericardial effusion. Unremarkable serologic and malignant work-up to date. No explanation for recurrent effusions and he required chest-tube placement. PET-CT showed the pericardium and mass on ECHO were PET avid. A CT-guided biopsy of the pericardial mass was conducted.Pathology demonstrated AS arising from the pericardium. The patient was initiated on Paclitaxel and Doxorubicin. He required bilateral tunnelled pleural catheters for 3 months. He was evaluated by Thoracic Surgery, but no surgical intervention was offered. DISCUSSION: What makes this diagnosis so hard? As in this case, the imaging may not initially guide us towards a cardiac malignancy. Similarly, this patient's blood work, microbiology and cytology from his pericardiocenteses and thoracenteses, were non-infectious and negative for malignant cells. This patient is also young – clinically, it would be much more likely to be a recurrent pericarditis. Interestingly, Chen et al (2020) noted that cardiac AS appears more in younger people. CONCLUSIONS: Fortunately, imaging with PET-CT completed roughly 2 and 4 months after diagnosis has shown decrease in the metabolic activity of the pericardium and size of the mass, in light of a grim prognosis. Hopefully earlier detection can help patients live healthier, longer. REFERENCE #1: Chen, T.W., Burns, J., Jones, R.L., & Huang, P.H. (2020). Optimal clinical management and the molecular biology of angiosarcomas. Cancers, 12(11), 3321. https://doi.org/10.3390/cancers12113321 REFERENCE #2: Li, W., Han, L., & Ye, Z. (2020). Primary pericardial angiosarcoma: A case report. Journal of Nuclear Cardiology, doi:10.1007/s12350-020-02470-0. DISCLOSURES: No relevant relationships by Elaine Dumoulin, source=Web Response No relevant relationships by Kathryn Lalonde, source=Web Response Consultant relationship with Atheneum Please note: $1-$1000 by Marcus Povitz, source=Web Response, value=Consulting fee Removed 04/28/2021 by Marcus Povitz, source=Web Responseindependant contractor relationship with Maple Respiratory Please note: $5001 - $20000 by Marcus Povitz, source=Web Response, value=interpretation fees Removed 04/28/2021 by Marcus Povitz, source=Web Response Advisory Committee Member relationship with Jazz corporation Please note: 2020 Added 04/28/2021 by Marcus Povitz, source=Web Response, value=Consulting fee

Coronavirus Disease 2019 (COVID-19) Coronary Vascular Thrombosis: Correlation with Neutrophil but Not Endothelial Activation

Severe coronavirus disease 2019 (COVID-19) increases the risk of myocardial injury that contributes to mortality. This study used multiparameter immunofluorescence to extensively examine heart autopsy tissue of 7 patients who died of COVID-19 compared to 12 control specimens, with or without cardiovascular disease. Consistent with prior reports, no evidence of viral infection or lymphocytic infiltration indicative of myocarditis was found. However, frequent and extensive thrombosis was observed in large and small vessels in the hearts of the COVID-19 cohort, findings that were infrequent in controls. The endothelial lining of thrombosed vessels typically lacked evidence of cytokine-mediated endothelial activation, assessed as nuclear expression of transcription factors p65 (RelA), pSTAT1, or pSTAT3, or evidence of inflammatory activation assessed by expression of intracellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), tissue factor, or von Willebrand factor (VWF). Intimal EC lining was also generally preserved with little evidence of cell death or desquamation. In contrast, there were frequent markers of neutrophil activation within myocardial thrombi in patients with COVID-19, including neutrophil-platelet aggregates, neutrophil-rich clusters within macrothrombi, and evidence of neutrophil extracellular trap (NET) formation. These findings point to alterations in circulating neutrophils rather than in the endothelium as contributors to the increased thrombotic diathesis in the hearts of COVID-19 patients.

Engineering a 3D human intracranial aneurysm model using liquid-assisted injection molding and tuned hydrogels

Physiologically relevant intracranial aneurysm (IA) models are crucially required to facilitate testing treatment options for IA. Herein, we report the development of a new in vitro tissue-engineered platform, which recapitulates the microenvironment, structure, and cellular complexity of native human IA. A new modified liquid-assisted injection molding technique was developed to fabricate a three-dimensional hollow IA model with clinically relevant IA dimensions within a mechanically tuned Gelatin Methacryloyl (GelMA) hydrogel. An endothelium lining was created inside the IA model by culturing human umbilical vein endothelial cells over pre-cultured human brain vascular smooth muscle cells. These cellularized IA models were subjected to medium perfusion at flow rates between 6.3 and 15.75 mL/min for inducing biomimetic vessel wall shear stress (10–25 dyn/cm2) to the cells for ten days. Both cell types maintained their secretome profiles and showed more than 96% viability, demonstrating the biocompatibility of the hydrogel during perfusion cell culture at such flow rates. Based on the characterized viscoelastic properties of the GelMA hydrogel and with the aid of a fluid-structure interaction model, the capability of the IA model in predicting the response of the IA to different fluid flow profiles was mathematically shown. With physiologically relevant behavior, our developed in vitro human IA model could allow researchers to better understand the pathophysiology and treatment of IA. Statement of significanceA three-dimensional intracranial aneurysm (IA) tissue model recapitulating the microenvironment, structure, and cellular complexity of native human IA was developed. • An endothelium lining was created inside the IA model over pre-cultured human brain vascular smooth muscle cells over at least 10-day successful culture. • The cells maintained their secretome profiles, demonstrating the biocompatibility of hydrogel during a long-term perfusion cell culture. • The IA model showed its capability in predicting the response of IA to different fluid flow profiles. • The cells in the vessel region behaved differently from cells in the aneurysm region due to alteration in hemodynamic shear stress. • The IA model could allow researchers to better understand the pathophysiology and treatment options of IA.

Small-Diameter Vessels Reconstruction Using Cell Tissue-Engineering Graft Based on the Polycaprolactone

Polycaprolactone (PCL) is widely applied for the construction of small-diameter tissue-engineered vascular grafts (TEGs) due to its biomechanical properties, slow degradation, and good biocompatibility. In the present study the TEG based on a tubular scaffold seeded with smooth muscle aortic cells (SMCs) in a rat abdominal aorta replacement model was tested. Polyester tubular scaffolds were generated by thermally induced phase separation and seeded with rat SMCs. To track the implanted SMCs in vivo, cells were labeled with superparamagnetic iron oxide nanoparticles (SPIONs). Histological evaluation of the migration of autologous endothelial cells (ECs) and formation of the endothelial lining was performed 4, 8, and 12 weeks after graft interposition. TEG demonstrated a high patency rate without any complications at the end of the 12-week period. The migration of ECs into the lumen of the implanted TEG and formation of the cell monolayer were already present at 4 weeks, as confirmed by histological analysis. The architecture of both neointima and neoadventitia were similar to those of the native vessel. SPION-labeled SMCs were detected throughout the TEG, indicating the role of these cells in the endothelization of scaffolds. The SMC-seeded scaffolds demonstrated improved patency and biointegrative properties when compared to the acellular grafts.

Preparation and Characterization of Targeted Microbubbles.

Targeting of microbubbles (ultrasound contrast agents for molecular imaging) has been researched for more than two decades. However, methods of microbubble preparation and targeting ligand attachment are cumbersome, complicated, and lengthy. Therefore, there is a need to simplify the targeted microbubble preparation procedure to bring it closer to clinical translation. The purpose of this publication is to provide a detailed description and explanation of the steps necessary for targeted microbubble preparation, functional characterization and testing. A sequence of the optimized and simplified procedures is presented for two systems: a biotin-streptavidin targeting pair model, and a cyclic RGD peptide targeting the recombinant αvβ3 protein, which is overexpressed on the endothelial lining of the tumor neovasculature. Here, we show the following: covalent coupling of the targeting ligand to a lipid anchor, assessment of the reagent quality, and tests that confirm the successful completion of the reaction; preparation of the aqueous precursor medium containing microbubble shell components, followed by microbubble preparation via amalgamation; assessment of the efficacy of lipid transfer onto the microbubble stabilizer shell; adjustment of microbubble size distribution by flotation at normal gravity to remove larger microbubbles that might be detrimental for in vivo use; assessment of microbubble size distribution by electrozone sensing; evaluation of targeted binding of the microbubbles to receptor-coated surface in a static binding assay test (in an inverted dish); and evaluation of targeted binding of the microbubbles to receptor-coated surface in a parallel plate flow chamber test.

CD99 and polymeric immunoglobulin receptor peptides deregulation in critical COVID-19: A potential link to molecular pathophysiology?

Identification of significant changes in urinary peptides may enable improved understanding of molecular disease mechanisms. We aimed towards identifying urinary peptides associated with critical course of COVID‐19 to yield hypotheses on molecular pathophysiological mechanisms in disease development. In this multicentre prospective study urine samples of PCR‐confirmed COVID‐19 patients were collected in different centres across Europe. The urinary peptidome of 53 patients at WHO stages 6–8 and 66 at WHO stages 1–3 COVID‐19 disease was analysed using capillary electrophoresis coupled to mass spectrometry. 593 peptides were identified significantly affected by disease severity. These peptides were compared with changes associated with kidney disease or heart failure. Similarities with kidney disease were observed, indicating comparable molecular mechanisms. In contrast, convincing similarity to heart failure could not be detected. The data for the first time showed deregulation of CD99 and polymeric immunoglobulin receptor peptides and of known peptides associated with kidney disease, including collagen and alpha‐1‐antitrypsin. Peptidomic findings were in line with the pathophysiology of COVID‐19. The clinical corollary is that COVID‐19 induces specific inflammation of numerous tissues including endothelial lining. Restoring these changes, especially in CD99, PIGR and alpha‐1‐antitripsin, may represent a valid and effective therapeutic approach in COVID‐19, targeting improvement of endothelial integrity.

English

It is difficult to diagnose pancreatic cysts in children. Any previous history of acute pancreatitis is very important because it can lead to a wide set of complications like pseudocyst, pancreatic necrosis, splenic venous thrombosis etc. The most known and common cause of pancreatic pseudocyst in children is trauma. The characteristic features of pancreatitis include abdominal pain, serum lipase or amylase values three times more than that of the normal range and characteristic radiological features. Pancreatic pseudocyst may occur in 15 % of children with acute pancreatitis as a complication.1 Pancreatic juice collection enclosed by a wall of granulation or fibrous tissue, is defined as a pseudocyst. As the resulting cyst has no true endothelial lining, it is classified as a pseudocyst.2 The pseudocyst contains inflammatory pancreatic fluid, mainly the lipase enzyme or semisolid matter. The incidence of pseudocyst is relatively low 1.6 % - 4.5 %, or 0.5 - 1 per 100 000 adults per year.2 Very few cases of pancreatic pseudocyst have been reported in world literature. Commonly, it develops as a sequel of acute or chronic pancreatitis. It develops around 4 weeks after the episode of acute pancreatitis.3 It is characterized by pancreatic inflammation, abdominal pain and raised levels of serum digestive enzymes.4 Here we discuss a case report of pancreatic pseudocyst in a 10-year-old male child presenting with history of abdominal pain and decreased appetite.

In Vivo Two-photon Imaging of Megakaryocytes and Proplatelets in the Mouse Skull Bone Marrow.

Platelets are produced by megakaryocytes, specialized cells located in the bone marrow. The possibility to image megakaryocytes in real time and their native environment was described more than 10 years ago and sheds new light on the process of platelet formation. Megakaryocytes extend elongated protrusions, called proplatelets, through the endothelial lining of sinusoid vessels. This paper presents a protocol to simultaneously image in real time fluorescently labeled megakaryocytes in the skull bone marrow and sinusoid vessels. This technique relies on a minor surgery that keeps the skull intact to limit inflammatory reactions. The mouse head is immobilized with a ring glued to the skull to prevent movements from breathing. Using two-photon microscopy, megakaryocytes can be visualized for up to a few hours, enabling the observation of cell protrusions and proplatelets in the process of elongation inside sinusoid vessels. This allows the quantification of several parameters related to the morphology of the protrusions (width, length, presence of constriction areas) and their elongation behavior (velocity, regularity, or presence of pauses or retraction phases). This technique also allows simultaneous recording of circulating platelets in sinusoid vessels to determine platelet velocity and blood flow direction. This method is particularly useful to study the role of genes of interest in platelet formation using genetically modified mice and is also amenable to pharmacological testing (study the mechanisms, evaluating drugs in the treatment of platelet production disorders). It has become an invaluable tool, especially to complement in vitro studies as it is now known that in vivo and in vitro proplatelet formation rely on different mechanisms. It has been shown, for example, that in vitro microtubules are required for proplatelet elongation per se. However, in vivo, they rather serve as a scaffold, elongation being mainly promoted by blood flow forces.

Functionalized supported membranes for quantifying adhesion of P. falciparum-infected erythrocytes

The pathology of Plasmodium falciparum malaria is largely defined by the cytoadhesion of infected erythrocytes to the microvascular endothelial lining. The complexity of the endothelial surface and the large range of interactions available for the infected erythrocyte via parasite-encoded adhesins make analysis of critical contributions during cytoadherence challenging to define. Here, we have explored supported membranes functionalized with two important adhesion receptors, ICAM1 or CD36, as a quantitative biomimetic surface to help understand the processes involved in cytoadherence. Parasitized erythrocytes bound to the receptor-functionalized membranes with high efficiency and selectivity under both static and flow conditions, with infected wild-type erythrocytes displaying a higher binding capacity than do parasitized heterozygous sickle cells. We further show that the binding efficiency decreased with increasing intermolecular receptor distance and that the cell-surface contacts were highly dynamic and increased with rising wall shear stress as the cell underwent a shape transition. Computer simulations using a deformable cell model explained the wall-shear-stress-induced dynamic changes in cell shape and contact area via the specific physical properties of erythrocytes, the density of adhesins presenting knobs, and the lateral movement of receptors in the supported membrane.

A Seventeen-Year Descriptive Study of Infective Endocarditis Features at a Tertiary, Teaching Hospital.

IntroductionInfective endocarditis (IE) is a microbial infection affecting the endothelial lining of the heart chambers and valves. Despite advances in diagnostic methods and management, IE still carries high levels of morbidity and mortality. There are no comprehensive data describing incidence, risk factors, and outcomes of IE in Saudi Arabia.Our study aims to describe the epidemiological and clinical characteristics and outcomes of adult patients with IE treated in a tertiary, Teaching Hospital.MethodsThis is a descriptive, retrospective review of charts (between January 2003 and June 2019) conducted at King Abdulaziz University Hospital. We included all patients 16 years and older with a definitive diagnosis of IE based on Duke Criteria. We collected the following information: demographics, risk factors, comorbidities, microbial type, antibiotic choice, complications, laboratory data, echocardiography data, and mortality.ResultsWe found a total of 60 adult patients with definitive diagnoses of IE: 55% of them were males, and the mean age was 48.71 ± 18.3 years. Hypertension was the most common comorbidity, affecting 23 patients (38.3%), followed by end-stage renal disease (ESRD) in 20 patients (33.3%) and diabetes in 17 (28.3%). Staphylococcus aureus was the most common organism (25%), and vancomycin was the most prescribed antibiotic. Fifty-eight patients were treated medically (96.5%). Furthermore, 88% of the patients had vegetations, detected by echocardiography, and the majority had single-valve involvement. Sepsis was the most common complication, and the mortality rate was 36.7%.ConclusionThere was a small number of definitive IE cases over a 17-years span in our institution. Surprisingly, a higher mortality rate was found among our patients and a lower surgical intervention rate in comparison with the literature. Though we acknowledge the limitations of a retrospective, chart review study, we can speculate that the high mortality rate may be in part related to a higher number of virulent organisms, delayed presentation, and lack of prompt surgical intervention.

A Bioreactor Simulating Pulse-Pressure Mediated Circumferential Stretch Stimulates Hematopoietic Stem Cell Formation

During fetal development, heartbeat precedes blood circulation and definitive hematopoietic stem cell (HSC) formation in the aorta-gonad-mesonephros (AGM) region. However, how the function and growth of heart and blood vessels are linked to the development of blood is largely unknown. Blood flow-mediated shear stress on the endothelial lining of the AGM stimulates the endothelial emergence of HSCs. A zebrafish mutant for cadherin 5, which has normal blood formation despite an early circulation arrest, enabled us to analyze the timing and intertwined roles of heartbeat in blood formation. Here we show that heartbeat and stretching of the blood vessel stimulate the HSC formation. We used three-dimensional (3D) digital Doppler ultrasound, microangiography, and time-lapse confocal microscopy to demonstrate that a beating heart, in cdh5-silenced zebrafish embryos, produces pulsation in blood vessels despite the lack of cardiac output and active blood circulation. Our time-lapse confocal imaging of cd41:eGFP+ HSCs emerging from flk1:mCherry+ endothelium from the cdh5-silenced embryos, followed by machine learning analysis of pulsating blood vessels, further establishing that pulse-pressure on the arterial endothelial lining of AGM regulates the endothelial emergence of HSCs. To understand the relationship between pulse pressure, biomechanical stretching of endothelial lining, and HSC formation, we recreated pulsating blood vessel-like conditions in a bioreactor by applying cyclic strain on mouse E11.5 AGM-derived hemogenic endothelial cells. Cyclic strain-mediated Trpv4 activation in hemogenic endothelial cells both stimulated HSC development and rescued hematopoiesis in the silent heart (tnnt2)-silenced embryos, which lacked blood flow and heartbeat. Therefore, heartbeat-mediated biomechanical stretching of hemogenic endothelial cells in the AGM stimulates trpv4 channels during the endothelial-to-HSC transition. Our findings advance our fundamental understanding of the developmental cues and 3D microenvironmental mechanisms regulating HSC formation. Our model could establish hemogenic endothelial cells as a potential source of bone marrow-independent HSCs. DisclosuresNo relevant conflicts of interest to declare.

Silent hyperlipidaemia modulated vascular endothelial markers

The aetiology of ischemic heart diseases is mainly based on atherosclerosis of coronary artery. Inflammation and oxidative reactions are initiating and aggravating the illness resulting in pathological remodelling of vasculaturze at site of injury. Endothelium lining of blood vessels participated in the reaction biochemically through releasing some proteins into circulatory system which further complicate the condition. The aim of this study was to determine early diagnosed hyperlipidaemia-associated changes of the plasma level of some of these endothelial biomolecules. Compared to healthy control, hyperlipidaemic patients have significantly increased arginase, metalloendopeptidase, peroxidase, myeloperoxidase, and peroxynitrite with concomitant reduction in arylesterase and nitric oxide. The present study concluded that hyperlipidaemia play a great role in modulation of certain plasma protein markers which might be directly related to patient pathological condition or could be used as a tool for diagnosis or patient follow up indicating the stage of vasculature remodelling, healing, inflammation or resolution.

A CASE OF INFECTIVE ENDOCARDITIS COMPLICATED BY ACUTE ISCHEMIC STROKE

Infective endocarditis is an infectious and inammatory process involving endothelial lining of heart structures and valves. Cerebrovascular complications (CVCs) frequently occur in patients who are in the active stage of infective endocarditis (IE), and result from cerebral septic embolization of an endocardial vegetation. Acute stroke due to septic emboli is a particularly dreaded complication , with a frequency of 25-35%. Here we present a case of 32 year old male patient, who comes to the ER with high grade fever and palpitations since 9 days. On examination we found hyperdynamic impulse with decrescendo type systolic murmur at mitral area and we decided to do a blood workup and also requested a 2D ECHO. Blood culture and 2D ECHO showed different species of streptococci and mitral regurgitation respectively. Based on the investigations we started the patient on antibiotics, However, on the day 7 of treatment, patient developed slurring of speech and hemiparesis followed by motor aphasia. We sent the patient for brain MRI that showed acute infarct in left central semioval, left corona radiata and left perisylvian region. Acute ischemic stroke is the complication of the infective endocarditis and we started tpAalong with intravenous antibiotics after which he experienced signicant clinical improvement in few days.

CORONARY ARTERY DISEASE (CAD): INTERPLAY OF NUTRITION, SERUM PARAMETERS AND GENETICS

Coronary artery disease (CAD) is a leading cause of death worldwide. The death rate is decreasing in developed countries due to awareness, but the disease burden is increasing in developing countries. Pakistan is a country with high prevalence of CAD. The serum lipids have long been implicated in the development of CAD by the deposition of mainly LDL on endothelial lining resulting in atherosclerosis. Progression to CAD involves environmental as well as genetic factors. The genetic component is due to the contribution from various low to modest effect size variants in many genes. Common variants have been used to construct a genetic risk score (GRS) to calculate the risk of future CAD. In conclusion, lifestyle interventions in concert with the knowledge of genetic predisposition based on family history and use of population data may one day lead to the development of personalized medicine for the treatment and prevention of CAD.

Complement C1s cleaves PfEMP1 at interdomain conserved sites inhibiting Plasmodium falciparum cytoadherence

Cytoadhesion of Plasmodium falciparum-infected erythrocytes (IEs) to the endothelial lining of blood vessels protects parasites from splenic destruction, but also leads to detrimental inflammation and vessel occlusion. Surface display of the P. falciparum erythrocyte membrane protein 1 (PfEMP1) adhesion ligands exposes them to host antibodies and serum proteins. PfEMP1 are important targets of acquired immunity to malaria, and through evolution, the protein family has expanded and diversified to bind a select set of host receptors through antigenically diversified receptor-binding domains. Here, we show that complement component 1s (C1s) in serum cleaves PfEMP1 at semiconserved arginine motifs located at interdomain regions between the receptor-binding domains, rendering the IE incapable of binding the two main PfEMP1 receptors, CD36 and endothelial protein C receptor (EPCR). Bioinformatic analyses of PfEMP1 protein sequences from 15 P. falciparum genomes found the C1s motif was present in most PfEMP1 variants. Prediction of C1s cleavage and loss of binding to endothelial receptors was further corroborated by testing of several different parasite lines. These observations suggest that the parasites have maintained susceptibility for cleavage by the serine protease, C1s, and provides evidence for a complex relationship between the complement system and the P. falciparum cytoadhesion virulence determinant.