Difference between revisions of "Team:NRP-UEA-Norwich/Modeling/Glyco2D"

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<p class="space10">To create the glycogen structures we made the following assumptions: :</p>
 
<p class="space10">To create the glycogen structures we made the following assumptions: :</p>
 
<p class="space10">&bull; Be the major metabolic substrate for colonocytes. Without butyrate for energy, colon cells undergo autophagy <br/>&bull; Maintain an acidic luminal pH, which prevents the production and absorption of carcinogenic factors <br/>&bull; Boost the mucosa of the gut and the immune system</p>
 
 
<p class = "space10">At the extra-intestinal level butyrate may</p>
 
  
 
<p class="space10">&bull;The branching points on the chain are always the 5th and 9th glucose molecule on the chain.<br/>&bull; All chains are equal in length  <br/>&bull; The branching degree is two on each chain, except on the final tier.</p>
 
<p class="space10">&bull;The branching points on the chain are always the 5th and 9th glucose molecule on the chain.<br/>&bull; All chains are equal in length  <br/>&bull; The branching degree is two on each chain, except on the final tier.</p>
  
            <p class="space20" style="text-align: center;"><b>We are particularly interested in the relationship between butyrate and colorectal cancers.</b></p>
 
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<div class="col-md-6 left">
     <p class="space20">Butyrate has been shown to inhibit cell proliferation and induce apoptosis in carcinoma cell lines by hyper-acetylating histones through inhibition of histone deacetylase (HDAC) and inducing gene silencing leading to apoptosis (5). Additionally, studies in rats have shown that increasing the amount of butyrate in the gut resulted in significant reduction in smooth muscle cell contractility, which lowers the risk of colon cancer (6). Another study confirmed the direct correlation of increased butyrate in the colon with a reduced tumor mass formation (7).</p>
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     <p class="space20">The software creates a pool of glucose units which are used to build the structure one tier at a time. Each time a new chain is about to be built, the software checks from a total of 24 possible directions and eliminates those that would grow toward the inner parts of the structure as it is not physically possible that the molecule is synthesized towards the core of the structure. The procedure to make this elimination is to discard the growth of any chain with a distance between its end and the centre of the molecule that is less than the distance of another chain belonging to two preceding tiers. This method generates a molecule with a more circular shape.</p>
  
<p class="space20">People consuming typical Western diets do not consume enough dietary fibre. For example, the average American only consumes 8 g a day; far less than the recommended 20 to 30 g per day (8). In addition, the microbiome differs between individuals. Some individuals have fewer bacteria that contain the  butyrate biosynthetic pathway. The most abundant strains of butyrate producing bacteria in the gut was demonstrated to be Eubacterium rectum and <i>E. halliii</i> (9).  The overall quantity of SCFAs produced in the colon is dependent on two factors: the amount of resistant carbohydrate molecules that pass to the colon for fermentation by colonic bacteria and bacteria with SCFA biosynthetic pathways being present in the microbiome.</p>
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<p class="space20">To make it easier to visualise, the software does not allow for chains to cross paths on the same plane, which does reduce the number of valid tiers compared to a three dimensional model. If there is more than one possible valid chain then the software will randomly select which valid chain to build.
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Revision as of 19:41, 13 September 2015

House of Carbs

Glyco2D

We built Glyco2D based on the mathematical model described by Meléndez-Hevia E et al (1) This model described the structural properties of glycogen based on different parameters such as chain length, branching degree or the number of tiers. The model was able to demonstrate the optimal values of these parameters for maximizing the glucose stored in the smallest volume and the number of non-reducing ends. These optimal values were branching degree of 2, chain length of 13 glucose units and approximately 12 tiers (1). The software we developed uses these properties to predict the structure of the molecule.

The software was created in C++ using openGL. The individual glucose molecules are represented by black squares and they are used as building blocks for the chains and branches.

...

To create the glycogen structures we made the following assumptions: :

•The branching points on the chain are always the 5th and 9th glucose molecule on the chain.
• All chains are equal in length
• The branching degree is two on each chain, except on the final tier.

The software creates a pool of glucose units which are used to build the structure one tier at a time. Each time a new chain is about to be built, the software checks from a total of 24 possible directions and eliminates those that would grow toward the inner parts of the structure as it is not physically possible that the molecule is synthesized towards the core of the structure. The procedure to make this elimination is to discard the growth of any chain with a distance between its end and the centre of the molecule that is less than the distance of another chain belonging to two preceding tiers. This method generates a molecule with a more circular shape.

To make it easier to visualise, the software does not allow for chains to cross paths on the same plane, which does reduce the number of valid tiers compared to a three dimensional model. If there is more than one possible valid chain then the software will randomly select which valid chain to build.

...

House of Carbs is taking two approaches to increase the levels of butyrate in the colon.

References

1. Haggar F, Boushey R. Colorectal Cancer Epidemiology: Incidence, Mortality, Survival, and Risk Factors. Clinics in Colon and Rectal Surgery. 2009; 22(4): p. 191-197.

2. Food and Drug Adminstration. Food and Drug Administration. [Online].; 2015 [cited 2015 August 24.] Available from: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=101.76

3. Elmståhl HL. Resistant starch content in a selection of starchy foods on the Swedish market. European Journal Of Clinical Nutrition. 2002 June; 56(6): p. 500-505

4. Zeng H, Lazarova DL, Bordonaro M. Mechanisms linking dietary fiber, gut microbiota and colon cancer prevention. World Journal of Gastrointestinal Oncology. 2014; 6(2): p. 41-51.

5. Canani RB, Di Costanzo M, Leone L, Pedata M, Meli R, Calignano A. Potential beneficial effects of butyrate in intestinal and extraintestinal diseases. World Journal of Gastroenterology. 2011 March 28; 17(12): p. 1519-1528.

6. Bajkaa BH, Clarkea JM, Toppinga DL, Cobiacc L, Abeywardenaa MY, Patten GS. Butyrylated starch increases large bowel butyrate levels and lowers colonic smooth muscle contractility in rats. Nutrition Research. 2010; 30: p. 427-424.

7. McIntyre A, Gibson PR, Young GP. Butyrate production from dietary fibre and protection against large bowel cancer in a rat model. Gut. 1993; 34: p. 386-391.

8. Murphy MM, Douglass JS, Birkett A. Resistant starch intakes in the United States. J Am Diet Assoc. 2008 Jan;108(1):67–78.

9. Louis P, Young P, Holtrop G, Flint HJ. Diversity of human colonic butyrate-producing bacteria revealed by analysis of the butyryl-CoA:acetate CoA-transferase gene. Environ Microbiol. 2010 Feb;12(2):304–14.

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