Team:NTU-Singapore/Project

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<div id="menu" class="hp clearfix main"><div class="grid_4 link"><span class="gray">Hard at work!</span></div><div class="grid_1 link">[[Team:NTU-Singapore | Home]]</div><div class="grid_2 link selflink">[[Team:NTU-Singapore/Project | <span class="selflink">pLaq''U''<span class="sup">e</span> Out!</span>]]</div><div class="grid_3 link">[[Team:NTU-Singapore/HPA | Human Practice]]</div><div class="grid_2 link">[[Team:NTU-Singapore/Notebook | Notebook]]</div><div class="grid_2 link">[[Team:NTU-Singapore/About/Team | About Us]]</div><div class="grid_2 link contact">[[Team:NTU-Singapore/Contact | Contact Us!]]</div></div>
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<div id="menu" class="hp clearfix main"><div class="grid_4 link"><span class="gray">Hard at work!</span></div><div class="grid_1 link">[[Team:NTU-Singapore | Home]]</div><div class="grid_2 link selflink">[[Team:NTU-Singapore/Project | <span class="selflink">pLaq''U''<span class="sup">e</span> Out!</span>]]</div><div class="grid_2 link">[[Team:NTU-Singapore/HPA | DIYbio]]</div><div class="grid_3 link">[[Team:NTU-Singapore/Notebook/Deliverables | Accomplishments!]]</div><div class="grid_2 link">[[Team:NTU-Singapore/Notebook | Notebook]]</div><div class="grid_2 link">[[Team:NTU-Singapore/About/Team | About Us]]</div></div>
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[[Team:NTU-Singapore/Project | Why Atherosclerosis?]]
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[[Team:NTU-Singapore/Project | '''p'''Laq''U''<span class="sup">e</span> '''Out''!''''']]
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[[Team:NTU-Singapore/Project/System | System Specifications]]
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[[Team:NTU-Singapore/Project/Approach | Research Approach]]
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[[Team:NTU-Singapore/Project/Prototype | Prototype System]]
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[[Team:NTU-Singapore/Project/Prototype/Sense | Sensing Device &laquo;&nbsp;&nbsp;]]
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[[Team:NTU-Singapore/Project/Proposal | Research proposal]]
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[[Team:NTU-Singapore/Project/Prototype/Sense | Sense Device &laquo;&nbsp;&nbsp;]]
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[[Team:NTU-Singapore/Project/Prototype/Degrade | Degradation Device &laquo;&nbsp;&nbsp;]]
[[Team:NTU-Singapore/Project/Prototype/Degrade | Degradation Device &laquo;&nbsp;&nbsp;]]
[[Team:NTU-Singapore/Project/Prototype/Image | Imaging Device &laquo;&nbsp;&nbsp;]]
[[Team:NTU-Singapore/Project/Prototype/Image | Imaging Device &laquo;&nbsp;&nbsp;]]
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[[Team:NTU-Singapore/Project/Prototype/Dilate | Dilation Device &laquo;&nbsp;&nbsp;]]
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[[Team:NTU-Singapore/Project/Wetlab | Wetlab Highlights]]
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[[Team:NTU-Singapore/Parts | Parts]]
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[http://partsregistry.org/cgi/partsdb/pgroup.cgi?pgroup=iGEM2009&group=NTU-Singapore Parts Submitted]
[[Team:NTU-Singapore/Project/References | References]]
[[Team:NTU-Singapore/Project/References | References]]
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[[Team:NTU-Singapore/Project/Conclusion | Conclusion]]
 
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<span class="title">The <span class="bold">Problem</span></span><br class="clear" />
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<span class="title"><span class="bold">p</span>Laq''U''e <span class="bold">Out''!''</span></span><br class="clear" />
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The '''NTU iGEM '09 Team''' has identified '''atherosclerosis''' as the problem we would like to tackle.
 
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Atherosclerosis is one of the major diseases affecting the world. In our research, we found the numbers were staggering, and growing. We also found that early diagnosis was rare, medications were not ideal and surgeries were a commonly used last resort.
+
The '''NTU iGEM '09 Team''' has identified '''atherosclerosis''' as the problem we would like to tackle.  
-
'''We asked ourselves what if we could design a biological system to  identify plaque sites and reduce the plaque volume ''in vivo''?'''
+
We propose to use a biological system that ''non-invasively'' identifies and degrades atherosclerotic plaque ''in vivo''.
<br class="clear" />
<br class="clear" />
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== Atherosclerosis in physiology ==
+
== Background ==
-
Atherosclerosis is an inflammatory disease caused by the buildup and hardening of fatty deposits on arterial walls. This accumulation eventually restricts the blood flow  through the affected vessels.
+
Atherosclerosis is one of the major diseases affecting the world. In our research, up to 7.2 million people are affected by coronary artery disease alone; a majority of these are caused by atherosclerosis [1]. In most cases, diagnosis is rare, medications are not ideal and surgeries are a commonly used last resort.
-
The condition starts with damage to arterial endothelium by risk factors like high blood pressure, high cholesterol, irritants like nicotine etc. The initial damage is then aggravated into an inflammatory condition by platelet clumping.
+
Atherosclerosis is an inflammatory disease caused by the buildup and hardening of fatty deposits on arterial walls. This accumulation eventually restricts the blood flow  through the affected vessels [2]. Here's an [http://www.youtube.com/watch?v=fLonh7ZesKs informative video] describing the nature of atherosclerotic buildup, and the deadly consequences.
-
This disruptive accumulation facilitates the accumulation of fatty deposits (oxidized LDL-cholesterol) and other cellular waste products. Special white blood cells that engulf the cholesterol derivatives, are unable to break them down. Hence these white blood cells become foam cells. Over time, all this debris hardens into a plaque.
 
 +
'''In our research and literature review, we identified the following characteristics of plaque buildup''':
-
The plaque proceeds to grow until the vessel's lumen becomes increasingly obstructed, leading to severe complications due to reduced blood flow.  
+
* Intuitively, we understand that decreased lumen area due to plaque leads to faster flow rate of blood.
 +
* Damaged arterial endothelium exhibits a surface protein, '''p-Selectin''', abundantly [3].
 +
** This p-Selectin binds selectively to the ligand, p-Selectin Glycoprotein (PSGL-1), via catch-bonds [4].
-
Here's an informative video describing the nature of atherosclerotic buildup, and the deadly consequences.<br class="clear" />
+
* Damage to arterial endothelial cells leads to decreased local levels of known vasodilator, '''Nitric Oxide''' [5].
 +
* The body is not able to break down '''cholesteryl esters''' in foam cells [6].
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<div class="grid_6 alpha"><html><center><object width="320" height="265"><param name="movie" value="http://www.youtube.com/v/fLonh7ZesKs&hl=en&fs=1&color1=0x2b405b&color2=0x6b8ab6"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/fLonh7ZesKs&hl=en&fs=1&color1=0x2b405b&color2=0x6b8ab6" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="320" height="265"></embed></object></center></html></div>
 
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As you can see, LDL-cholesterol buildup, and subsequent foam cell formation is the root cause of plaque buildup.
+
=== Present shortcomings ===
 +
Atherosclerotic plaque buildup is a gradual process. The body accommodates for any changes, hence delaying the onset of symptoms until it's too late. Symptoms themselves vary depending on which arteries exactly the plaque buildup develop [2,8].
-
The condition becomes increasingly irreversible as calcification sets in.
 
 +
As such, present medications are catered largely toward immediate relief of symptoms, and less on reversing the condition. Unfortunately, the medication is also accompanied by the need for a complete lifestyle change to prevent the problem from getting worse. More often than we would prefer, major surgeries, like bypass surgery (including open-heart surgery) & stent placement, become necessary. These surgeries are followed by long recovery periods, which may be devastating to patients.
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The problem then is that plaque buildup is not identified early enough for medication to actually reverse the condition, rather than alleviating the symptoms.<br class="clear" />
 
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It is clear that early stage diagnosis and treatment of atherosclerosis will be more effective & beneficial than late stage treatment.
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=== Engineering a solution ===
 +
Our proposed biological system seeks to overcome the shortcomings of present approaches, by being less intrusive & more efficient.
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=== Symptoms & Present treatments ===
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[[Image:NTUplaqueout2.jpg|center]]
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Atherosclerotic plaque buildup is a gradual process. It doesn't help that the body accommodates for any changes, hence delaying the onset of symptoms until it's too late. Symptoms themselves vary depending on which arteries exactly the plaque buildup is in.
 
-
'''Symptoms include''':
+
We propose the use of mammalian T-helper cells as a chassis. The advantage of using a T-helper cell is that expression/exhibition of PSGL-1 at the surface becomes trivial  [3].
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* ''If in arteries closer to the heart''
 
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** Chest pain (angina) &
 
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** other complications similar to heart attack conditions
 
 +
'''The chassis will contain the following devices working in synchrony.'''
-
* ''If in arteries leading to the brain''
 
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** Sudden numbness/weakness in limbs
 
-
** Slurred speech
 
-
** Drooping facial muscles etc.
 
 +
[[Image:NTUsysdev.gif|center|632px]]
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* ''If in arteries leading to limbs''
 
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** intermittent claudication (leg pain)
 
 +
* '''Sensing device''' will detect changes in physiological blood [NO] and regulate the other devices.
 +
** In healthy [NO] conditions, the '''Sensing device''' represses the other '''devices'''.
 +
** In low [NO], the device de-activates and the other devices activate.
-
As such, present medications are catered largely toward immediate relief of symptoms, and less on reversing the condition. Unfortunately, the medication is also accompanied by the need for a complete lifestyle change to prevent the problem from getting worse.
+
* '''Degradation device''' will secrete an enzyme to break down the lipid core.
 +
** Cholesteryl esterase is released to degrade cholesteryl esters.
-
'''Medications include''':
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* '''Imaging device''' will identify and monitor plaque sites ''in vivo''.
 +
** Infrared fluorescence protein generates a unique infrared signal.
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* Anti-coagulants
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* '''Dilation device''' will re-generate [NO] & feedback to shutdown.
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* Anti-platelets
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** Nitric oxide synthase produces NO to dilate the vessel after a programmed delay.
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* Beta-blockers
+
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* ACE inhibitors &
+
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* other cholesterol medications.
+
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More often that we would prefer, surgery becomes a necessary option due to the late-stage urgency. These are major surgeries, that will have drastic impacts on lifestyle and quality of life thereafter.
+
'''We will focus on designing a full-blown prototype system as a proof-of-concept, using E.Coli as our model organism, due to equipment and time limitations.'''
-
'''Surgical techniques include''':
 
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* Coronary angioplasty
+
Please proceed here to understand our [[Team:NTU-Singapore/Project/Approach | Research Approach]].
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* Bypass surgery (including open-heart surgery)
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* Stent placement &
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* Carotid artery surgery
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As you can see, none of these options are particularly appealing.
 
 +
== References/Literature ==
-
=== Characteristic bodily reactions ===
+
<div class="ref">
 +
# WHO Medical Centre (2009). "Cardiovascular diseases (CVDs)." from http://www.who.int/mediacentre/factsheets/fs317/en/index.html.
 +
# MayoClinic.com. (2008). "'''Definition of Arterioscleriosis.'''" from http://www.mayoclinic.com/health/arteriosclerosis-atherosclerosis/DS00525.
 +
# Eric Borges, W. T., Martin Steegmaier,* Thomas Moll,* Rupert Hallmann,§ Alf Hamann, and Dietmar Vestweber* (1997). "'''P-Selectin Glycoprotein Ligand-1 (PSGL-1) on T Helper 1 but Not on T Helper 2 Cells Binds to P-Selectin and Supports Migration into Inflamed Skin'''" Journal of Experimental Medicine 185.
 +
# W. Thomas, “'''Catch Bonds in Adhesion'''” Annu. Rev. Biomed. Eng., vol 10, 39-57, 2008.
 +
# Ferenc I. Tarr MD, P., Mária Sasvári MDb, Márton Tarr MD and Rozália Rácz MD (2005). "'''Evidence of Nitric Oxide Produced by the Internal Mammary Artery Graft in Venous Drainage of the Recipient Coronary Artery.'''" The Annals of Thoracic Surgery 80(5): 1728-1731.
 +
# G. K. Hansson, Anna-Karin L. Robertson, C. Soderberg-Naucler, “'''Inflammation and Atherosclerosis'''” Annu. Rev. Pathol. Mech. Dis., vol 1, 297-329, 2006.
 +
# Moniek N. Pieters, Sebastiaan Esbach, Donald Schouten, Adriaan Brouwer, Dick L. Knook, Theo J. C. Van Berkel, "'''Cholesteryl esters from oxidized low-density lipoproteins are in vivo rapidly hydrolyzed in rat kupffer cells and transported to liver parenchymal cells and bile'''", Hepatology Vol 19, Issue 6 , Pages 1459 - 1467
 +
# NIH. "'''How is Atherosclerosis Diagnosed?'''", from http://www.nhlbi.nih.gov/health/dci/Diseases/Atherosclerosis/Atherosclerosis_Diagnosis.html.
 +
# E. Galkina, K. Ley, “'''Immune and Inflammatory Mechanisms of Atherosclerosis'''” Annu. Rev. Immunol., vol 27, 165-97, 2009.
 +
# Anderson, T. J. M. (2003). "'''Nitric Oxide, Atherosclerosis and clinical relevance of endothelial dysfunction.'''" Heart Failure Reviews 8: 71 - 86.
 +
</div>
-
In our research and literature review, we identified the following characteristics of plaque buildup.
 
-
 
-
 
-
* '''Intuitively, we understand that decreased lumen area due to plaque leads to faster flow rate of blood.'''
 
-
 
-
 
-
* '''Research shows that damaged arterial endothelium exhibits p-selectin abundantly at the lumen surface to signal for help.'''
 
-
** This p-selectin binds selectively to p-selectin glycoprotein ligand (PSGL-1) via natural catch-bond mechanism, which works best in fast-flowing conditions.
 
-
 
-
 
-
* '''Research indicates that damage to arterial endothelial cells leads to decreased local levels of nitric oxide (NO) in blood.'''
 
-
** On a tangential note, NO is also a known vasodilator.
 
-
 
-
 
-
* '''We find that the lipid core in foam cells are in the form of oxidized cholesterols, ie. cholesteryl esters.'''
 
-
** The body is not able to break down cholesterol found in this form.
 
-
 
-
 
-
* '''Diagnosis of plaque is usually done in late-stage due to delayed symptoms.'''
 
-
** Reasons include the gradual buildup of plaque & bodily adjustment to initial stages of plaque buildup .
 
-
 
-
 
-
We hope to specifically identify plaque sites with these symptoms, and exploit some of these mechanisms to build our biological system.
 
-
 
-
 
-
 
-
=== Engineering a solution ===
 
-
 
-
From this list of characteristics, we will try to describe a solution that caters specifically to alleviating the atherosclerotic condition.
 
-
 
-
 
-
Our solution will factor in an intimate understanding of the anatomy of the plaque site, as well as the bodily adaptations to such damage. We will design our solution to work ''in vivo'' taking advantage of bodily signals and mechanisms to reduce the plaque buildup.
 
-
 
-
To see our proposed solution, please proceed to [[Team:NTU-Singapore/Project/System | System Specifications]].
 
-
 
-
 
-
 
-
== References/Literature ==
 
See the complete list of references [[Team:NTU-Singapore/Project/References | here]].
See the complete list of references [[Team:NTU-Singapore/Project/References | here]].

Latest revision as of 00:26, 22 October 2009

pLaqUe Out!


Contents


The NTU iGEM '09 Team has identified atherosclerosis as the problem we would like to tackle.

We propose to use a biological system that non-invasively identifies and degrades atherosclerotic plaque in vivo.


Background

Atherosclerosis is one of the major diseases affecting the world. In our research, up to 7.2 million people are affected by coronary artery disease alone; a majority of these are caused by atherosclerosis [1]. In most cases, diagnosis is rare, medications are not ideal and surgeries are a commonly used last resort.


Atherosclerosis is an inflammatory disease caused by the buildup and hardening of fatty deposits on arterial walls. This accumulation eventually restricts the blood flow through the affected vessels [2]. Here's an informative video describing the nature of atherosclerotic buildup, and the deadly consequences.


In our research and literature review, we identified the following characteristics of plaque buildup:

  • Intuitively, we understand that decreased lumen area due to plaque leads to faster flow rate of blood.
  • Damaged arterial endothelium exhibits a surface protein, p-Selectin, abundantly [3].
    • This p-Selectin binds selectively to the ligand, p-Selectin Glycoprotein (PSGL-1), via catch-bonds [4].
  • Damage to arterial endothelial cells leads to decreased local levels of known vasodilator, Nitric Oxide [5].
  • The body is not able to break down cholesteryl esters in foam cells [6].


Present shortcomings

Atherosclerotic plaque buildup is a gradual process. The body accommodates for any changes, hence delaying the onset of symptoms until it's too late. Symptoms themselves vary depending on which arteries exactly the plaque buildup develop [2,8].


As such, present medications are catered largely toward immediate relief of symptoms, and less on reversing the condition. Unfortunately, the medication is also accompanied by the need for a complete lifestyle change to prevent the problem from getting worse. More often than we would prefer, major surgeries, like bypass surgery (including open-heart surgery) & stent placement, become necessary. These surgeries are followed by long recovery periods, which may be devastating to patients.


Engineering a solution

Our proposed biological system seeks to overcome the shortcomings of present approaches, by being less intrusive & more efficient.


NTUplaqueout2.jpg


We propose the use of mammalian T-helper cells as a chassis. The advantage of using a T-helper cell is that expression/exhibition of PSGL-1 at the surface becomes trivial [3].


The chassis will contain the following devices working in synchrony.


NTUsysdev.gif


  • Sensing device will detect changes in physiological blood [NO] and regulate the other devices.
    • In healthy [NO] conditions, the Sensing device represses the other devices.
    • In low [NO], the device de-activates and the other devices activate.
  • Degradation device will secrete an enzyme to break down the lipid core.
    • Cholesteryl esterase is released to degrade cholesteryl esters.
  • Imaging device will identify and monitor plaque sites in vivo.
    • Infrared fluorescence protein generates a unique infrared signal.
  • Dilation device will re-generate [NO] & feedback to shutdown.
    • Nitric oxide synthase produces NO to dilate the vessel after a programmed delay.


We will focus on designing a full-blown prototype system as a proof-of-concept, using E.Coli as our model organism, due to equipment and time limitations.


Please proceed here to understand our Research Approach.


References/Literature

  1. WHO Medical Centre (2009). "Cardiovascular diseases (CVDs)." from http://www.who.int/mediacentre/factsheets/fs317/en/index.html.
  2. MayoClinic.com. (2008). "Definition of Arterioscleriosis." from http://www.mayoclinic.com/health/arteriosclerosis-atherosclerosis/DS00525.
  3. Eric Borges, W. T., Martin Steegmaier,* Thomas Moll,* Rupert Hallmann,§ Alf Hamann, and Dietmar Vestweber* (1997). "P-Selectin Glycoprotein Ligand-1 (PSGL-1) on T Helper 1 but Not on T Helper 2 Cells Binds to P-Selectin and Supports Migration into Inflamed Skin" Journal of Experimental Medicine 185.
  4. W. Thomas, “Catch Bonds in Adhesion” Annu. Rev. Biomed. Eng., vol 10, 39-57, 2008.
  5. Ferenc I. Tarr MD, P., Mária Sasvári MDb, Márton Tarr MD and Rozália Rácz MD (2005). "Evidence of Nitric Oxide Produced by the Internal Mammary Artery Graft in Venous Drainage of the Recipient Coronary Artery." The Annals of Thoracic Surgery 80(5): 1728-1731.
  6. G. K. Hansson, Anna-Karin L. Robertson, C. Soderberg-Naucler, “Inflammation and Atherosclerosis” Annu. Rev. Pathol. Mech. Dis., vol 1, 297-329, 2006.
  7. Moniek N. Pieters, Sebastiaan Esbach, Donald Schouten, Adriaan Brouwer, Dick L. Knook, Theo J. C. Van Berkel, "Cholesteryl esters from oxidized low-density lipoproteins are in vivo rapidly hydrolyzed in rat kupffer cells and transported to liver parenchymal cells and bile", Hepatology Vol 19, Issue 6 , Pages 1459 - 1467
  8. NIH. "How is Atherosclerosis Diagnosed?", from http://www.nhlbi.nih.gov/health/dci/Diseases/Atherosclerosis/Atherosclerosis_Diagnosis.html.
  9. E. Galkina, K. Ley, “Immune and Inflammatory Mechanisms of Atherosclerosis” Annu. Rev. Immunol., vol 27, 165-97, 2009.
  10. Anderson, T. J. M. (2003). "Nitric Oxide, Atherosclerosis and clinical relevance of endothelial dysfunction." Heart Failure Reviews 8: 71 - 86.


See the complete list of references here.



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