Biomedical subjects

Joy Roy

Publications and source records attributed to Joy Roy.

7 recordsLinked to original sources

PubMed2006

Reduced perlecan expression and accumulation in human carotid atherosclerotic lesions.

Heparan sulfate in the extracellular matrix of the artery wall has been proposed to possess anti-atherogenic properties by interfering with lipoprotein retention, suppression of inflammation, and inhibition of smooth muscle cell growth. Previously, the amount of heparan sulfate in atherosclerotic lesions from humans and animals has been shown to be reduced but the identity or identities of the heparan sulfate molecules being down regulated in this disease are not known. In this study, atherosclerotic lesions were retrieved from 44 patients undergoing surgery for symptomatic carotid stenosis. Normal iliac arteries from organ donors were used as controls. Analysis of the specimens by gene microarray showed a selective reduction in perlecan gene expression, whereas, expression of the other heparan sulfate proteoglycans in the artery wall, agrin and collagen XVIII, remained unchanged. Expression of the large chondroitin sulfate proteoglycan, versican, also remained unchanged. Real-time PCR confirmed the decrease in perlecan gene expression and the unchanged expression of versican. The findings were supported by immunohistochemical analysis demonstrating a reduced accumulation of both perlecan core protein and heparan sulfate in carotid lesions. The study demonstrates a reduction of perlecan mRNA-expression and protein deposition in human atherosclerosis, which in part explains the low levels of heparan sulfate in this disease.

Aged↗

PubMed2005

Difference in matrix-degrading protease expression and activity between thrombus-free and thrombus-covered wall of abdominal aortic aneurysm.

OBJECTIVE: It has been suggested that the intraluminal thrombus of abdominal aortic aneurysms (AAAs) predisposes for AAA rupture. Here, we examined the possibility that the intraluminal thrombus influences expression and activity of matrix-degrading proteases in the AAA wall. METHODS AND RESULTS: Twenty patients undergoing elective repair of AAAs were included. From each patient, specimens from both thrombus-covered and thrombus-free wall were taken for analysis. Gene arrays and quantitative real-time polymerase chain reaction showed that matrix metalloproteinase (MMP)-1, -7, -9, and -12 expressions were upregulated in the thrombus-free wall compared with the thrombus-covered wall. Immunohistochemistry confirmed the differential expression of MMP-9 but also localized MMP-9 to the interface between the thrombus and the underlying vessel wall. MMP-9 expression was colocalized with the presence of macrophages. Similar expression patterns were observed for urokinase plasminogen activator (uPA), uPA receptor, and plasminogen activator inhibitor-1. Gelatinase activity was detected in the same regions as MMP-9 protein expression, ie, within the thrombus-free wall and in the interface between the thrombus and the underlying wall. CONCLUSIONS: The present work demonstrates that protease expression and activity differs within the aneurysm wall. The source and activity of the proteases responsible for the degradation of the thrombus-covered wall need to be further determined.

Aorta, Abdominal↗

PubMed2004

Control of smooth muscle cell proliferation in vascular disease.

PURPOSE OF REVIEW: Smooth muscle cell proliferation has previously been regarded as a central feature in vascular disease. The role of this process has recently been substantially re-evaluated, and we have reconsidered the functional importance of smooth muscle cell proliferation, the origin of proliferating smooth muscle cells in lesions, and the mechanisms whereby smooth muscle cell proliferation is controlled. In this review, we summarize recent progress in the understanding of smooth muscle cell proliferation, with a particular focus on how interactions between the extracellular matrix, smooth muscle cells, and mitogens control critical steps in this process. RECENT FINDINGS: Irrespective of the origin of smooth muscle cells in vascular lesions, fundamental interactions between the extracellular matrix and cell surface integrins are necessary in order to initiate a proliferative response in a quiescent smooth muscle cell, in a similar manner to any non-malignant cell. These interactions trigger intracellular signaling and cell cycle entry, which facilitate cell cycle progression and proliferation by mitogens. In addition, extracellular matrix interactions may also control the availability and activity of growth factors such as heparin-binding mitogens, which can be sequestered by heparan sulfate containing extracellular matrix components and regulate smooth muscle cell proliferation. SUMMARY: New insights into mechanisms whereby the extracellular matrix takes part in the control of smooth muscle cell proliferation suggest a number of putative targets for future therapies that can be applied to increase plaque stability, prevent the clinical consequences of atherosclerosis and improve outcomes after interventional procedures and organ transplantation.

Animals↗

PubMed2004

Ultra-high-throughput microarray generation and liquid dispensing using multiple disposable piezoelectric ejectors.

The authors have constructed an array of 12 piezoelectric ejectors for printing biological materials. A single-ejector footprint is 8 mm in diameter, standing 4 mm high with 2 reservoirs totaling 76 micro L. These ejectors have been tested by dispensing various fluids in several environmental conditions. Reliable drop ejection can be expected in both humidity-controlled and ambient environments over extended periods of time and in hot and cold room temperatures. In a prototype system, 12 ejectors are arranged in a rack, together with an X - Y stage, to allow printing any pattern desired. Printed arrays of features are created with a biological solution containing bovine serum albumin conjugated oligonucleotides, dye, and salty buffer. This ejector system is designed for the ultra-high-throughput generation of arrays on a variety of surfaces. These single or racked ejectors could be used as long-term storage vessels for materials such as small molecules, nucleic acids, proteins, or cell libraries, which would allow for efficient preprogrammed selection of individual clones and greatly reduce the chance of cross-contamination and loss due to transfer. A new generation of design ideas includes plastic injection molded ejectors that are inexpensive and disposable and handheld personal pipettes for liquid transfer in the nanoliter regime.

Cell Line↗

PubMed2003

Small GTP-binding protein Rac is an essential mediator of vascular endothelial growth factor-induced endothelial fenestrations and vascular permeability.

BACKGROUND: Vascular endothelial growth factor/vascular permeability factor (VEGF/VPF) induces both angiogenesis and vascular permeability. Although its angiogenic activity has been well characterized, the signaling pathways of VEGF-induced permeability remain poorly understood. METHODS AND RESULTS: Using the mouse corneal micropocket assay, Miles assay, and a combination of cytochemical, electron microscopic, and biochemical assays, we demonstrate that VEGF-induced vascular leakage partly can be separated from its angiogenic activity. VEGF but not FGF-2 induced capillaries with a highly fenestrated endothelium, a feature linked with increased vascular permeability. A cell-permeable Rac antagonist (TAT-RacN17) converted VEGF-induced, leaky vascular plexuses into well-defined vascular networks. In addition, this Rac mutant blocked formation of VEGF-induced endothelial fenestrations and vascular permeability but only partially inhibited angiogenesis. Studies on endothelial cell cultures further revealed that VEGF stimulated phosphorylation of VEGF receptor-2 (VEGFR-2), leading to activation of Rac as well as increased phosphorylation of phospholipase Cgamma (PLCgamma), protein kinase B (Akt), endothelial nitric oxide synthase (eNOS), and extracellular regulated kinase (Erk1/2). We further found that phosphatidylinositol-3-OH kinase (PI3K) acted upstream of Rac and Akt-eNOS in VEGF/VEGFR-2 signaling. CONCLUSIONS: Our findings indicate that the small GTP-binding protein Rac is a key component in mediation of VEGF-induced vascular permeability but less so in neovascularization. This may have conceptual implications for applying Rac antagonists in treatment and prevention of VEGF-induced vascular leakage and edema in connection with ischemic disorders.

Animals↗

PubMed2003

Influence of intraluminal thrombus on structural and cellular composition of abdominal aortic aneurysm wall.

INTRODUCTION: It has been suggested that the intraluminal thrombus of abdominal aortic aneurysm (AAA) affects the underlying vessel wall. Aneurysm enlargement has been associated with growth of thrombus, and rupture has been proposed to occur after bleeding into the thrombus. To examine how thrombus affects the vessel wall, we compared the morphology of aneurysm wall covered with thrombus with wall segments exposed to flowing blood. Material and methods Sixteen patients (14 men, 2 women; age range, 56-79 years) undergoing elective repair of AAA, where computed tomography scans showed thrombus and segments of the aneurysm wall exposed to flowing blood, were included in the study. Specimens from the aneurysm were taken for light and electron microscopy. Masson trichrome staining was performed for wall thickness determination and demonstration of collagen, and Weigert-van Gieson staining for elastin. The cellular composition was analyzed by immunohistochemistry with antibodies against CD3 for T cells, CD4 for T helper cells, CD8 for T cytotoxic cells, CD20 for B cells, CD68 for macrophages, and smooth muscle alpha-actin for smooth muscle cells (SMCs). Caspase-3 staining and TUNEL analysis were performed to evaluate apoptosis. RESULTS: The aneurysm wall covered with thrombus was thinner and contained fewer elastin fibers, and the few that were found were often fragmented. This part of the wall also contained fewer SMCs and more apoptotic nuclei than the wall exposed to flowing blood. Clusters of inflammatory cells were detected in the media of the aneurysm wall and in higher numbers in the parts covered with thrombus. Electron microscopy showed that the aneurysm wall without thrombus contained a dense collagenous matrix with differentiated SMCs. In the segment covered with thrombus, SMCs were more dedifferentiated (synthetic) and apoptotic or necrotic. There were also an increased number of inflammatory cells located in close contact with SMCs in various stages of apoptosis. CONCLUSION: The aneurysm wall covered with thrombus is thinner and shows more frequent signs of inflammation, apoptosis of SMCs, and degraded extracellular matrix. These findings suggest that thrombus formation and accumulation of inflammatory cells may perturb the structural integrity and stability of the vessel wall and thereby increase the risk for aneurysm rupture.

Aged↗

PubMed2002

Fibronectin promotes cell cycle entry in smooth muscle cells in primary culture.

Smooth muscle cell proliferation after arterial injury is regulated by growth factors and components of the extracellular matrix. We have previously demonstrated that fibronectin promotes a phenotypic modulation of freshly isolated rat smooth muscle cells from a contractile to a synthetic phenotype in primary culture and supports the ability of the cells to respond to growth factors. Here, we analyzed if fibronectin promotes cell cycle entry in freshly isolated rat aortic smooth muscle cells during primary culture. Cell cycle analysis showed that cells seeded on fibronectin remained in the G(0)/G(1) phase of the cell cycle during the first 6 days of culture. During this period, there was an increased expression of cyclin D1 and p27(KIP1) in the absence of exogenous growth factors. Addition of serum was followed by enhanced cyclin D1 expression, decreased p27(KIP1) levels, hyperphosphorylation of Rb protein, induction of cyclin A and cyclin D3 expression, and cell cycle progression into S phase. The results indicate that fibronectin initiates cell cycle entry in freshly isolated smooth muscle cells by promoting the induction of cyclin D1 and thereby facilitates further cell cycle progression together with growth factors.

Animals↗