Essay Color Key

Free Essays
Unrated Essays
Better Essays
Stronger Essays
Powerful Essays
Term Papers
Research Papers




angiogenesis blood vessel growth

Rate This Paper:

Length: 837 words (2.4 double-spaced pages)
Rating: Red (FREE)      
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

PDFG induces proliferation of fibroblasts, microglia, and smooth muscle. It is stored in platelet granules and is released following platelet aggregation. PDGF may also serve as a chemotactic agent for inflammatory cells.

Platelets circulate in the blood and are derived from megakaryocytic in the marrow. Like erythrocytes, they are anucleate. However, unlike erythrocytes, they contain numerous intracytoplasmic granules and are the source of numerous proinflammatory mediators. In fact, they are quantitatively the greatest single source of vasoactive amines in the body. They also are a rich source of thromboxane A2. It is their activation that, in part, initiates the vascular phase of the acute inflammatory response (see Fig. 2-13 in text). To have them play this role makes imminently good sense, because they are present in large numbers throughout the circulation, i.e., some are always in close proximity to an inciting stimulus.

Vasoactive Literally translated, this adjective means that a substance has the capacity to alter the physiologic state, especially the tone and caliber, of a vessel.
Platelet-Derived Growth Factor (PDGF), a dimeric glycoprotein composed of two A and/or B chains, is the principal mitogen in serum for mesenchymal cells. Applications include culture of various cell types derived from connective tissue. It can also be used to study chemotaxis, wound healing, and bone repair. Another member of the PDGF family is the Vascular Endothelial Growth Factor (VEGF) with endothelial cell-specific activities (e.g., angiogenic and mitogenic factor).
Platelet-derived growth factor (PDGF) [1-3 reviews], a factor released from platelets upon clotting, is responsible for stimulating the proliferation of fibroblasts in vitro [4-6]. PDGF is also produced by a number of cell types besides platelets and is mitogen for vascular smooth muscle cells, bone cells, cartilage cells, connective tissue cells and some blood cells [7-9]. PDGF is stored in platelet alpha granules and released upon platelet activation. PDGFs are disulfide-linked dimers. The subunits of the PDGF dimers are homologous polypeptides designated PDGF-A and PDGF-B chains. Natural PDGFs can exist either as homodimers (PDGF-AA, PDGF-BB) or heterodimers (PDGF-AB). Two splice variants exist for the A-chain (211AA for the long isoform, 196AA for the most abundant short isoform), and C-terminal proteolytic processing apparently occurs for the B-chain (and possibly the A-chain) [10-12]. A-chain long isoform and B-chain contain a cell retention signal at the C-term end, which must be removed in order to release a freely circulating PDGF [13-16].
Two distinct human PDGF receptor transmembrane binding proteins have been identified [17,18]. PDGFR-alpha binds each of the three forms of PDGF dimers with high affinity. PDGFR-beta binds both PDGF-BB and PDGF-AB but has no reported binding to PDGF-AA [3,19,20]. PDGF binding activates intracellular tyrosine kinase, leading to autophosphorylation of the cytoplasmic domain of PDGFR, as well as phosphorylation of other intracellular substrates .[19,20]
Because there are differences between cells relative to the amounts of alpha- and beta-receptors that they express, and because of the variability in PDGF isomer binding to receptors, PDGF is involved in many biological activities, including hyperplasia, chemotaxis, embryonic neuron fiber development, and respiratory tubule epithelial cells development. PDGF binding has been linked to upregulation of ICAM-1 in vascular smooth muscle cells [21], transient induction of T cell IL-2 secretion [22], down-regulation of IL-4 and IFN-gamma production [22] and modulation of thrombospondin expression and secretion [23].
PDGF being a potent mitogen for connective tissue cells, it is implicated in cancer-driven angiogenesis [24].
Topic:
Vigorous blood vessels that grow rapidly are the signs of a strong, healthy body, right? Wrong of course a properly functioning circulatory system is vital to good health, but excessive angiogenesis blood vessel growth is not. One example of that fact is the eye condition known as retinopathy. This disease occurs when blood vessels in the retina begin to grow at an unusually rapid rate, branching out into the clear fluids that fill the middle part of the eye. The vessels often hemorrhage resulting in scar tissue that reduces the amount of light that reaches the retina. Retinopathy is often associated with diabetes, and afflicts about 40% of those who have had that disease for more that fifteen years.
     Consequently, finding the cause of the rapid growth of blood vessels was an important medical question. A group of compounds, the vascular endothelial group factor (VEGF) family, has been shown to induce blood vessel growth. This finding enabled scientist to begin the search for a substance capable of blocking these factors and inhibiting excessive blood vessel growth in conditions such as retinopathy.
     Clinical trials were begun in early 2000 on squalamine , and antiangiogenic chemical classified as an aminosterol. Initial results showed squalamine capable of reducing abnormal blood vessel growth characteristic of retinopathy. In the future, squalamine may prove useful in preventing retinopathy and other eye afflictions.
     Questions and Problems
1)     Considerable research has been done in recent years on the identification of other types of growth factors. Select a growth factor and prepare a brief report summarizing its function
2)     What other applications can you think of or find out about for a compound that would block blood vessel growth?

How to Cite this Page

MLA Citation:
"angiogenesis blood vessel growth." 123HelpMe.com. 30 Sep 2014
    <http://www.123HelpMe.com/view.asp?id=52995>.




Related Searches





Important Note: If you'd like to save a copy of the paper on your computer, you can COPY and PASTE it into your word processor. Please, follow these steps to do that in Windows:

1. Select the text of the paper with the mouse and press Ctrl+C.
2. Open your word processor and press Ctrl+V.

Company's Liability

123HelpMe.com (the "Web Site") is produced by the "Company". The contents of this Web Site, such as text, graphics, images, audio, video and all other material ("Material"), are protected by copyright under both United States and foreign laws. The Company makes no representations about the accuracy, reliability, completeness, or timeliness of the Material or about the results to be obtained from using the Material. You expressly agree that any use of the Material is entirely at your own risk. Most of the Material on the Web Site is provided and maintained by third parties. This third party Material may not be screened by the Company prior to its inclusion on the Web Site. You expressly agree that the Company is not liable or responsible for any defamatory, offensive, or illegal conduct of other subscribers or third parties.

The Materials are provided on an as-is basis without warranty express or implied. The Company and its suppliers and affiliates disclaim all warranties, including the warranty of non-infringement of proprietary or third party rights, and the warranty of fitness for a particular purpose. The Company and its suppliers make no warranties as to the accuracy, reliability, completeness, or timeliness of the material, services, text, graphics and links.

For a complete statement of the Terms of Service, please see our website. By obtaining these materials you agree to abide by the terms herein, by our Terms of Service as posted on the website and any and all alterations, revisions and amendments thereto.



Return to 123HelpMe.com

Copyright © 2000-2014 123HelpMe.com. All rights reserved. Terms of Service