Difference between revisions of "Team:Virginia"

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<h2>
 
House of Carbs
 
<p>A Novel Solution to Minimizing Postprandial Hyperglycemic Spikes</p>
 
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<h1>Project Overview</h1>
 
<h3 id="h3-1">The Problem: Diabetes Mellitus and Hyperglycemia</h3>
 
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<p>From diabetes mellitus a number of devastating complications, such as amputations, blindness, crippling neuropathies, and many others, can arise from increased blood sugar levels on a regular basis, but many of
 
the major complications of diabetes arise from drastic fluctuations in the blood glucose
 
level (Ceriello et al., 2012). Up to two-thirds of people with diabetes die of
 
cardiovascular disease (CVD) brought about by diabetes-related macrovascular diseases
 
(Deshpande et al. 2008). In fact, the risk for cardiovascular disease mortality is 2 to 4
 
times higher in people with diabetes than in people who do not have diabetes.
 
Additionally, diabetic retinopathy is the most common microvascular complication
 
among people with diabetes and results in more than 10,000 new cases of blindness per
 
year. Retinopathy is associated with prolonged hyperglycemia; it is slow to develop, and
 
there is some evidence that it can begin to develop as early as 7 years before clinical
 
diagnosis of diabetes (Deshpande et al., 2008).
 
</p>
 
<p>Postprandial (post-meal) blood sugar spikes specifically are one of the most
 
damaging complications of diabetes (Parkin et al., 2002). Many diabetics are able to
 
effectively manage post-meal glycemic spikes with self-administered doses of insulin,
 
but these hyperglycemic incidents still kill more Americans per year than any other
 
diabetes-related complications (Parkin et al., 2002). Arguably, the gravest consequence of
 
glycemic spikes in diabetes patients is the development of progressive macrovascular
 
disease (MVD), which affects the large blood vessels of the body, hardening and
 
blocking these vessels (Ceriello et al., 2012). MVD is the leading cause of death among
 
T2DM patients in the United States, causing up to 65% of diabetes-related deaths, making it a huge target for diabetes treatments research (Deshpande et al., 2008). MVD
 
also frequently leads to other severe complications such as ischemia in the extremities
 
and blindness (Haffner et al., 1998).
 
</p></div>
 
<h3 id="h3-2">Controlling Hyperglycemic Spikes</h3><div id="des2">
 
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<p>For many T1DM and T2DM patients, it has been shown that the regular
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<p id="above-nav">University of Virginia iGEM 2015</p>
control and management of blood glucose levels prevents many of the vascular
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complications of the disease, but most of the time control over glucose is difficult to
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<a href="https://twitter.com/Virginia_iGEM"><img id="twitter" src="/wiki/images/2/2c/Virginia_twitter_white.png"></img></a>
attain because the self-dosing insulin treatment system that a lot of moderately to
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severely sick diabetes patients use is often hard to calibrate and use (Parkin et al., 2002).
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</p>
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<p>Compared to sucrose-rich food, starch-rich food has been found to create less
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fluctuation in blood glucose levels, and thus is beneficial to diabetes patients and
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hyperglycemia patients. There is evidence that this flatter response caused by a starch
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rich meal is associated with the slower rate of digestion of complex sugars versus simple
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sugars (Jenkins, Wolever, & Jenkins, 1988). Thus, if some of the simple sugars are first
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converted into complex saccharides inside the E. coli and then released back into small
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intestine, a similar flatter glycemic response will take place, which will be beneficial to
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the patients.
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</p></div>
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<h3 id="h3-3">Our Devices</h3><div id="des3">
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<p style="margin-bottom:30px;"> We have assembled one plasmid with genes that dictate a controllable level of simple sugars uptake and one plasmid to produce glucan and fructan from simple sugars and then lyse to release the complex sugars back into the environment. In essence, this microbial device runs on two genetic devices -- an uptake circuit and a polymerization circuit. </p></div>
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<p style="font-style:italic; border-top:1px dotted #007bb6"> In order to learn more details, please visit the <a href="/Team:Virginia/Project">Project page.</a> </p>
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<h3>References</h3>
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<p>A. Ceriello, S. Colagiuri, (2011). Guideline for management of postmeal glucose in
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diabetes. International Diabetes Federation Guideline Development Group,
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http://www.idf.org/sites/default/files/postmeal%20glucose%20guidelines.pdf ,
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Accessed May. 6th, 2015
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</p>
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<p>American Diabetes Association (2014). National Diabetes Statistics Report.
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http://www.cdc.gov/diabetes/pubs/statsreport14/national-diabetes-report-web.pdf
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Accessed May. 5th, 2015
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</p>
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<p>Anal, A. K., & Singh, H. (2007). Recent advances in microencapsulation of probiotics for
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industrial applications and targeted delivery. Trends in Food Science &
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Technology, 18(5), 240–251. http://doi.org/10.1016/j.tifs.2007.01.004
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</p>
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<p>Anan, F., Masaki, T., Eto, T., Fukunaga, N., Iwao, T., Kaneda, K., ... Yoshimatsu, H.
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(2008). Postchallenge Plasma Glucose and Glycemic Spikes Are Associated with
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Pulse Pressure in Patients with Impaired Glucose Tolerance and Essential
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Hypertension. Hypertension Research, 31(8), 1565–1571.
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http://doi.org/10.1291/hypres.31.1565
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</p>
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<p>AHFS Consumer Medication Information [Internet]. Bethesda (MD): American Society
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of Health-System Pharmacists, Inc.; ©2008. Acarbose; [revised 2015 Feb. 15;
+
reviewed 2015 Apr. 28; cited 2015 May. 3]; Available from:
+
http://www.nlm.nih.gov/medlineplus/druginfo/meds/ a696015.html
+
</p>
+
<p>AHFS Consumer Medication Information [Internet]. Bethesda (MD): American Society
+
of Health-System Pharmacists, Inc.; ©2008. Pramlintide; [revised 2015 Feb. 15;
+
reviewed 2015 Apr. 28; cited 2015 May. 3]; Available from:
+
http://www.nlm.nih.gov/medlineplus/druginfo/meds/a605031.html
+
</p>
+
<p>Banguela, A., Arrieta, J. G., Rodríguez, R., Trujillo, L. E., Menéndez, C., & Hernández,
+
L. (2011). High levan accumulation in transgenic tobacco plants expressing the
+
Gluconacetobacter diazotrophicus levansucrase gene. Journal of Biotechnology,
+
154(1), 93–98. http://doi.org/10.1016/j.jbiotec.2011.04.007
+
</p>
+
<p>Barr EL, Zimmet PZ, Welborn TA et al. (2007). "Risk of cardiovascular and all-cause
+
mortality in individuals with diabetes mellitus, impaired fasting glucose, and
+
impaired glucose tolerance: the Australian Diabetes, Obesity, and Lifestyle Study
+
(AusDiab)". Circulation 116 (2): 151–7.
+
</p>
+
<p>Bernard, A. M., Anderson, L., Cook, C. B., & Phillips, L. S. (1999). What do internal
+
medicine residents need to enhance their diabetes care? Diabetes Care, 22(5),
+
661–666. http://doi.org/10.2337/diacare.22.5.661
+
</p>
+
<p>Boada C, Martínez-Moreno J. Pathophysiology of diabetes mellitus type 2: beyond the
+
duo "insulin resistance-secretion deficit.". Nutricion Hospitalaria [serial online].
+
March 2, 2013;28:78-87. Available from: Fuente Académica, Ipswich, MA.
+
Accessed April 16, 2015.
+
</p>
+
<p>B. Göke, H. F. (1995). Voglibose (AO128) Is an Efficient α-Glucosidase Inhibitor and
+
Mobilizes the Endogenous GLP-1 Reserve. Digestion, 56(6), 493–501.
+
http://doi.org/10.1159/000201282
+
</p>
+
<p>Brown, J. B., Harris, S. B., Webster-Bogaert, S., Wetmore, S., Faulds, C., & Stewart, M.
+
(2002). The role of patient, physician and systemic factors in the management of
+
type 2 diabetes mellitus. Family Practice, 19(4), 344–349.
+
http://doi.org/10.1093/fampra/19.4.344
+
</p>
+
<p>Butterworth, P. J., Warren, F. J., & Ellis, P. R. (2011). Human α-amylase and starch
+
digestion: An interesting marriage. Starch - Stärke, 63(7), 395–405.
+
http://doi.org/10.1002/star.201000150
+
</p>
+
<p>Centers for Disease Control and Prevention. (2014). National Diabetes Statistics Report.</p>
+
<p>Chiasson, J.-L., Josse, R. G., Gomis, R., Hanefeld, M., Karasik, A., & Laakso, M. (2002).
+
Acarbose for prevention of type 2 diabetes mellitus: the STOP-NIDDM
+
randomised trial. The Lancet, 359(9323), 2072–2077.
+
http://doi.org/10.1016/S0140-6736(02)08905-5
+
</p>
+
<p>Chiasson, J.-L., Josse, R. G., Hunt, J. A., Palmason, C., Rodger, N. W., Ross, S. A., ...
+
Wolever*, T. M. S. (1994). The Efficacy of Acarbose in the Treatment of Patients
+
with Non–Insulin-Dependent Diabetes Mellitus: A Multicenter, Controlled
+
Clinical Trial. Annals of Internal Medicine, 121(12), 928–935.
+
http://doi.org/10.7326/0003-4819-121-12-199412150-00004
+
Crude and Age-Adjusted Rate per 100 of Civilian, Noninstitutionalized Population with
+
Diagnosed Diabetes, United States, 1980–2011. (2014, September 5). Retrieved
+
April 24, 2015, from
+
http://www.cdc.gov/diabetes/statistics/prev/national/figage.htm
+
</p>
+
<p>Dedonder, R. 1966. Levansucrase from Bacillus subtilis. Methods Enzymol. 8:500–505.</p>
+
<p>Deshpande, A. D., Harris-Hayes, M., & Schootman, M. (2008). Epidemiology of diabetes
+
and diabetes-related complications. Physical therapy, 88(11), 1254-1264.
+
</p>
+
<p>D.M. Nathan, P.A. Cleary, J.Y. Backlund, S.M. Genuth, J.M. Lachin, T.J. Orchard, et al.,
+
Intensive diabetes treatment and cardiovascular disease in patients with type 1
+
diabetes, N Engl J Med, 353 (2005), pp. 2643–2653
+
</p>
+
<p>D.R. Whiting, L. Guariguata, C. Weil, J. Shaw, IDF diabetes atlas: global estimates of the
+
prevalence of diabetes for 2011 and 2030 Diabetes Res Clin Pract, 94 (2011), pp.
+
311–321
+
</p>
+
<p>Duncan, A. E. (2012). Hyperglycemia and Perioperative Glucose Management.Current
+
Pharmaceutical Design, 18(38), 6195–6203.
+
</p>
+
<p>Edelman, P. S., Maier, H., & Wilhelm, K. (2012). Pramlintide in the Treatment of
+
Diabetes Mellitus. BioDrugs, 22(6), 375–386. http://doi.org/10.2165/0063030-
+
200822060-00004
+
</p>
+
<p>Ferraris, R. P., Yasharpour, S. A. S. A. N., Lloyd, K. C., Mirzayan, R. A. F. F. Y., &
+
Diamond, J. M. (1990). Luminal glucose concentrations in the gut under normal
+
conditions. American Journal of Physiology-Gastrointestinal and Liver
+
Physiology, 259(5), G822-G837.
+
</p>
+
<p>Gay, P., Le Coq, D., Steinmetz, M., Ferrari, E., & Hoch, J. A. (1983). Cloning structural
+
gene sacB, which codes for exoenzyme levansucrase of Bacillus subtilis:
+
expression of the gene in Escherichia coli. Journal of bacteriology,153(3), 1424-
+
1431.
+
</p>
+
<p>Gray, G. M., & Ingelfinger, F. J. (1966). Intestinal absorption of sucrose in man:
+
interrelation of hydrolysis and monosaccharide product absorption. Journal of
+
Clinical Investigation, 45(3), 388.
+
</p>
+
<p>Grant, R. W., Buse, J. B., & Meigs, J. B. (2005). Quality of Diabetes Care in U.S.
+
Academic Medical Centers Low rates of medical regimen change. Diabetes Care,
+
28(2), 337–442. http://doi.org/10.2337/diacare.28.2.337
+
</p>
+
<p>Grant, R. W., Pirraglia, P. A., Meigs, J. B., & Singer, D. E. (2004). Trends in complexity
+
of diabetes care in the United States from 1991 to 2000. Archives of Internal
+
Medicine, 164(10), 1134–1139. http://doi.org/10.1001/archinte.164.10.1134
+
</p>
+
<p>Halschou, K., Bukhave, K., & Rikardt, J. (2012). Intestinal Disaccharidase Activity and
+
Uptake of Glucose from Sucrose. In S. Chackrewarthy (Ed.), Glucose Tolerance.
+
InTech. Retrieved from http://www.intechopen.com/books/glucose-
+
tolerance/intestinal-disaccharidase-activity-and-uptake-of-glucose-from-sucrose
+
</p>
+
<p>Hanahan, D. (1983). Studies on transformation of Escherichia coli with plasmids. Journal
+
of Molecular Biology, 166(4), 557–580.
+
</p>
+
<p>Hoffmann, J., & Spengler, M. (1997). Efficacy of 24-Week Monotherapy With Acarbose,
+
Metformin, or Placebo in Dietary-Treated NIDDM Patients: The Essen-II Study.
+
The American Journal of Medicine, 103(6), 483–490.
+
http://doi.org/10.1016/S0002-9343(97)00252-0
+
Intensive blood-glucose control with sulphonylureas or insulin compared with
+
conventional treatment and risk of complications in patients with type 2 diabetes
+
(UKPDS 33). UK Prospective Diabetes Study (UKPDS) Group.
+
</p>
+
<p>Jenkins, D. J. A., Wolever, T. M. S., & Jenkins, A. L. (1988). Starchy Foods and
+
Glycemic Index. Diabetes Care, 11(2), 149–159.
+
http://doi.org/10.2337/diacare.11.2.149
+
</p>
+
<p>Jones, M. C. (2007). Therapies for diabetes: pramlintide and exenatide. American Family
+
Physician, 75(12), 1831–1835.
+
</p>
+
<p>J Reizer, S. L. S. (1992). Functional interactions between proteins of the
+
phosphoenolpyruvate:sugar phosphotransferase systems of Bacillus subtilis and
+
Escherichia coli. The Journal of Biological Chemistry, 267(13), 9158–69.
+
Jenkins, D. J., Wolever, T. M., & Jenkins, A. L. (1988). Starchy foods and glycemic
+
index. Diabetes care, 11(2), 149-159.
+
</p>
+
<p>Kumar, Vinay; Fausto, Nelson; Abbas, Abul K.; Cotran, Ramzi S. ; Robbins, Stanley L.
+
(2005). Robbins and Cotran Pathologic Basis of Disease (7th ed.). Philadelphia,
+
Pa.: Saunders. pp. 1194–1195. ISBN 0-7216-0187-1. Lancet. 1998 Sep 12;
+
352(9131):837-53.
+
</p>
+
<p>Kundig, W., Ghosh, S., & Roseman, S. (1964). PHOSPHATE BOUND TO HISTIDINE
+
IN A PROTEIN AS AN INTERMEDIATE IN A NOVEL PHOSPHO-
+
TRANSFERASE SYSTEM. Proceedings of the National Academy of Sciences of
+
the United States of America, 52, 1067–1074.
+
</p>
+
<p>Lebovitz, H. E. (1997). ALPHA-GLUCOSIDASE INHIBITORS. Endocrinology and
+
Metabolism Clinics of North America, 26(3), 539–551.
+
http://doi.org/10.1016/S0889-8529(05)70266-8
+
</p>
+
<p>Lourens-Hattingh, A., & Viljoen, B. C. (2001). Yogurt as probiotic carrier food.
+
International Dairy Journal, 11(1–2), 1–17. http://doi.org/10.1016/S0958-
+
6946(01)00036-X
+
</p>
+
<p>Malagelada, J. R., Bazzoli, F., Elewaut, A., Fried, M., Krabshuis, J. H., Lindberg, G., ...
+
Vakil, N. (2007). World Gastroenterology Organisation Practice Guidelines.
+
Dysphagia. Retrieved from http://almacen-
+
gpc.dynalias.org/publico/Dysphagia%20WGO%202004%20Ingles.pdf
+
</p>
+
<p>Man, C. D., Camilleri, M., & Cobelli, C. (2006). A System Model of Oral Glucose
+
Absorption: Validation on Gold Standard Data. IEEE Transactions on Biomedical
+
Engineering, 53(12), 2472–2478. http://doi.org/10.1109/TBME.2006.883792
+
</p>
+
<p>Meigs, J. B., Nathan, D. M., Wilson, P. W., Cupples, L. A., & Singer, D. E. (1998).
+
Metabolic risk factors worsen continuously across the spectrum of nondiabetic
+
glucose tolerance. The Framingham Offspring Study. Annals of Internal Medicine,
+
128(7), 524–533.
+
</p>
+
<p>Narimasa, S., Tatsuo, H., Mitsutaka, Y., & Toshio, I. (1979). Action of human pancreatic
+
and salivary α-amylases on maltooligosaccharides: Evaluation of kinetic
+
parameters. Clinica Chimica Acta, 97(2–3), 253–260.
+
http://doi.org/10.1016/0009-8981(79)90423-6
+
</p>
+
<p>National Diabetes Data Group. (1979). Classification and Diagnosis of Diabetes Mellitus
+
and Other Categories of Glucose Intolerance. Diabetes, 28(12), 1039–1057.
+
http://doi.org/10.2337/diab.28.12.1039
+
</p>
+
<p>Nissle, A. (1959). [Explanations of the significance of colonic dysbacteria & the
+
mechanism of action of E. coli therapy (mutaflor)]. Die Medizinische, 4(21),
+
1017–1022.
+
</p>
+
<p>Parkin, C. G., & Brooks, N. (2002). Is postprandial glucose control important? Is it
+
practical in primary care settings?. Clinical Diabetes, 20(2), 71-76.
+
</p>
+
<p>Patterson, Joan (2013). Many Schools Cutting Back on Physical Education. Las Vegas
+
Review - Journal.
+
Prevalence of diabetes, impaired fasting glucose, and impaired glucose tolerance in U.S.
+
adults. The Third National Health and Nutrition Examination Survey, 1988-1994.
+
</p>
+
<p>Peng, C.-K., Buldyrev, S. V., Havlin, S., Simons, M., Stanley, H. E., & Goldberger, A. L.
+
(1994). Mosaic organization of DNA nucleotides. Physical Review E, 49(2),
+
1685–1689. http://doi.org/10.1103/PhysRevE.49.1685
+
</p>
+
<p>Rathmann, W., & Giani, G. (2004). Global Prevalence of Diabetes: Estimates for the
+
Year 2000 and Projections for 2030: Response to Wild et al. Diabetes Care, 2568-
+
2569.
+
</p>
+
<p>Recorbet, G. H. I. S. L. A. I. N. E., Robert, C., Givaudan, A., Kudla, B., Normand, P., &
+
Faurie, G. (1993). Conditional suicide system of Escherichia coli released into
+
soil that uses the Bacillus subtilis sacB gene. Applied and environmental
+
microbiology, 59(5), 1361-1366.
+
</p>
+
<p>Ried, J. L., and A. Collmer. 1987. An nptI-sacB-sacR cartridge for constructing directed,
+
unmarked mutations in Gram-negative bacteria by marker exchange-eviction
+
mutagenesis. Gene 57:239–246.
+
</p>
+
<p>Riddle, M., Frias, J., Zhang, B., Maier, H., Brown, C., Lutz, K., & Kolterman, O. (2007).
+
Pramlintide Improved Glycemic Control and Reduced Weight in Patients With
+
Type 2 Diabetes Using Basal Insulin. Diabetes Care, 30(11), 2794–2799.
+
http://doi.org/10.2337/dc07-0589
+
</p>
+
<p>Saydah, S. H., Miret, M., Sung, J., Varas, C., Gause, D., & Brancati, F. L. (2001).
+
Postchallenge Hyperglycemia and Mortality in a National Sample of U.S. Adults.
+
Diabetes Care, 24(8), 1397–1402. http://doi.org/10.2337/diacare.24.8.1397
+
</p>
+
<p>Snelling, Anatasia; Korba, Casey; Burkey, Alyvia (2007). The National School Lunch
+
and Competitive Food Offerings and Purchasing Behaviors of High School
+
Students, 77(10), 701-705.
+
</p>
+
<p>Sonnenborn, Ulrich; Schulze, Jurgen. 2009. The Non-Pathogenic Escherichia coli strain
+
Nissle 1917 - Features of a Versatile Probiotic. Microbial Ecology in Health and
+
Disease, (21), 122-158.
+
</p>
+
<p>S.M. Haffner, S. Lehto, T. Ronnemaa, K. Pyorala, M. Laakso, Mortality from coronary
+
heart disease in subjects with type 2 diabetes and in nondiabetic subjects with and
+
without prior myocardial infarction, N Engl J Med, 339 (1998), pp. 229–234
+
</p>
+
<p>Schultz, M. (2008). Clinical use of E. coli Nissle 1917 in inflammatory bowel disease.
+
Inflammatory Bowel Diseases, 14(7), 1012–1018.
+
http://doi.org/10.1002/ibd.20377
+
</p>
+
<p>Seifter, S., & Dayton, S. (1950). The estimation of glycogen with the anthrone reagent.
+
Archives of Biochemistry, 25(1), 191–200.
+
</p>
+
<p>Shulman, N. B., Martinez, B., Brogan, D., Carr, A. A., & Miles, C. G. (1986). Financial
+
cost as an obstacle to hypertension therapy. American Journal of Public Health,
+
76(9), 1105–1108.
+
</p>
+
<p>Suwattee, P., Lynch, J. C., & Pendergrass, M. L. (2003). Quality of Care for Diabetic
+
Patients in a Large Urban Public Hospital. Diabetes Care, 26(3), 563–568.
+
http://doi.org/10.2337/diacare.26.3.563
+
</p>
+
<p>Temelkova-Kurktschiev, T. S., Koehler, C., Henkel, E., Leonhardt, W., Fuecker, K., &
+
Hanefeld, M. (2000). Postchallenge plasma glucose and glycemic spikes are more
+
strongly associated with atherosclerosis than fasting glucose or HbA1c level.
+
</p>
+
<p>Diabetes Care, 23(12), 1830–1834. http://doi.org/10.2337/diacare.23.12.1830
+
What are normal blood glucose levels? Retrieved from Virginia Mason Medical Center
+
website: https://www.virginiamason.org/whatarenormalbloodglucoselevels.
+
Accessed: May. 5th ,2015
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<h1>Modeling</h1>
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<p>Modeling is a major component of our project since in the scope of this project, the direct effect of the transformed <i>E. coli</i> strain on reducing glycemic spikes cannot be tested in animal models, e.g. Rattus norvegicus. Instead, we will model the theoretical decrease in blood sugar levels based on data obtained from experiments that are performed in liquid solutions containing various concentrations of glucose and/or fructose. Thus, our first modeling goal is to predict the usefulness of our system and guide our experimental design, troubleshooting and future potential improvements.  In addition, since our project is related to health and would need to be orally taken to be effective, safety concerns should also be counted for. Thus, our second modeling goal is to show the degree of possible horizontal gene transfer between our modified <i>E. coli</i>  and endogenous gut flora.</p>
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<h3>First Part: Modeling the efficacy of our design</h3>
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<h4>Uptake of the sugar by the transformed strain</h4>
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<p>The uptake of the sugar is the cornerstone of the design. It is modeled as a function of promoter strength and concentration of free sugars. Thus we can find the range of uptake that is most physiologically reasonable and back-calculate the strength of the promoter to achieve the desired level of sugar uptake. Since the relative strength of the promoter family J23100 (Anderson, 2006) has been characterized, we could determine which promoter from the family is optimal based on our model. The model is made to fit data obtained from characterization process.</p>
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<!--[Picture/Table to come]-->
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<h4>Modeling of the glgC and sacB function</h4>
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<p>Conversion of simple sugars into complex saccharides is modeled as a function of simple sugar concentrations and expression level of the enzymes, glgC and sacB. The concentration profile of complex sugars is modeled as a function of free sugar concentrations inside cells, expression level of the genes and time. The cell death and release of the sugars will relate to concentration profile of complex sugars. The model will be used to estimate the input, the released complex sugars, for the model of reabsorption.</p><p>
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Glycogen concentration is measured by absorbance. Because the recommended wavelength by
 +
 
 +
the assay kit manufacturer is 570. Based on wavelength/absorbance plot provided by the
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manufacturer, we determined that the out of the wavelength filters that we have, the 540 nm is
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 +
most ideal. So we used the absorbance measured at 540 nm to reproduce a plot.
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<a href="/wiki/images/4/4e/Virginia_glgCAssays.pdf"><h5>Download the Assay Data Here</h5></a>
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<!--[Picture/Table to come]-->
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<h4>Reabsorption of complex saccharides by the human body</h4>
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<p>Previous study has suggested that high molecular weight levan is digested into low molecular weight product and free fructose by gastric juice but not pancreatic enzymes (Yamamoto et al., 1999). Thus once inside the small intestine, the levan will not be digested and will reach the colon and be excreted out of the human body. Thus we only need to model the digestion and absorption of glycogen. Recently, a physiological model of intestinal absorption of glucose has been developed, and specifically the Ra has been estimated as a function of the amount of glucose in the gut (Man, Camilleri, & Cobelli, 2006):</p>
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<p>Because the enzyme responsible for the breakdown of polysaccharides, pancreatic alpha-amylase (AMY2A), has been well-characterized (Narimasa, Tatsuo, Mitsutaka, & Toshio, 1979), we can use  Equation 2 (Butterworth, Warren, & Ellis, 2011) to estimate the amount of glucose from the amount of glycogen.</p>
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-->
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<p>The total amount (mass) of glucose can be assumed to equal the total amount of glycogen when all glycogen is depleted. Then, we can model the function of our transformed strain inside small intestine as a three-step linear process, where the free sugars are first taken by the bacteria, then polymerized inside the bacteria and then released after about 2 hours. The Ra will be compared with the Ra estimated without our device to quantify the effectiveness of our device to delay and reduce PPG level. Additionally, we can constrain our model to achieve an ideal Ra and solve for the parameters such as promoter strength of the two devices.</p>
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<h3>Second Part: Modeling the rate of horizontal gene transfer</h3>
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<p>Horizontal gene transfer between our modified <i>E. coli</i>  and indigenous gut flora is something we must address as a safety concern. The most rapid means of horizontal gene transfer in bacteria is through the shuttle of plasmids. Transfer of plasmids occurs at about 1*10^-9 (ml cell^-1 h^-1, ref). And the number of <i>E. coli</i>  is decreasing (as determined by the growth assay). Thus the total number of transferred plasmid within one load could be modeled as an ODE. The number is calculated to be #, given the SacB could kill #% of the cells after 2 hrs.</p>
 +
 +
<p>Ideally, we could transform our modified <i>E. coli</i>  with a circuit composed of a consensus <i>E. coli</i>  promoter, GFP, a consensus ASF 361 promoter and RFP. If we measure the expression level of  GFP and RFP in the <i>E. coli</i>  and ASF 361 respectively and get distinct FU readings, we could use a flow cytofluorometer to find out the specific plasmid transfer rate of our modified <i>E. coli</i>  to a representative of the indigenous gut flora. However, we did not have the time to complete this experiment. </p>
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Revision as of 14:16, 18 September 2015

Modeling - U.Va. iGEM

University of Virginia iGEM 2015

Modeling

Modeling is a major component of our project since in the scope of this project, the direct effect of the transformed E. coli strain on reducing glycemic spikes cannot be tested in animal models, e.g. Rattus norvegicus. Instead, we will model the theoretical decrease in blood sugar levels based on data obtained from experiments that are performed in liquid solutions containing various concentrations of glucose and/or fructose. Thus, our first modeling goal is to predict the usefulness of our system and guide our experimental design, troubleshooting and future potential improvements. In addition, since our project is related to health and would need to be orally taken to be effective, safety concerns should also be counted for. Thus, our second modeling goal is to show the degree of possible horizontal gene transfer between our modified E. coli and endogenous gut flora.

First Part: Modeling the efficacy of our design

Uptake of the sugar by the transformed strain

The uptake of the sugar is the cornerstone of the design. It is modeled as a function of promoter strength and concentration of free sugars. Thus we can find the range of uptake that is most physiologically reasonable and back-calculate the strength of the promoter to achieve the desired level of sugar uptake. Since the relative strength of the promoter family J23100 (Anderson, 2006) has been characterized, we could determine which promoter from the family is optimal based on our model. The model is made to fit data obtained from characterization process.

Modeling of the glgC and sacB function

Conversion of simple sugars into complex saccharides is modeled as a function of simple sugar concentrations and expression level of the enzymes, glgC and sacB. The concentration profile of complex sugars is modeled as a function of free sugar concentrations inside cells, expression level of the genes and time. The cell death and release of the sugars will relate to concentration profile of complex sugars. The model will be used to estimate the input, the released complex sugars, for the model of reabsorption.

Glycogen concentration is measured by absorbance. Because the recommended wavelength by the assay kit manufacturer is 570. Based on wavelength/absorbance plot provided by the manufacturer, we determined that the out of the wavelength filters that we have, the 540 nm is most ideal. So we used the absorbance measured at 540 nm to reproduce a plot.

Download the Assay Data Here

Reabsorption of complex saccharides by the human body

Previous study has suggested that high molecular weight levan is digested into low molecular weight product and free fructose by gastric juice but not pancreatic enzymes (Yamamoto et al., 1999). Thus once inside the small intestine, the levan will not be digested and will reach the colon and be excreted out of the human body. Thus we only need to model the digestion and absorption of glycogen. Recently, a physiological model of intestinal absorption of glucose has been developed, and specifically the Ra has been estimated as a function of the amount of glucose in the gut (Man, Camilleri, & Cobelli, 2006):

Because the enzyme responsible for the breakdown of polysaccharides, pancreatic alpha-amylase (AMY2A), has been well-characterized (Narimasa, Tatsuo, Mitsutaka, & Toshio, 1979), we can use Equation 2 (Butterworth, Warren, & Ellis, 2011) to estimate the amount of glucose from the amount of glycogen.

The total amount (mass) of glucose can be assumed to equal the total amount of glycogen when all glycogen is depleted. Then, we can model the function of our transformed strain inside small intestine as a three-step linear process, where the free sugars are first taken by the bacteria, then polymerized inside the bacteria and then released after about 2 hours. The Ra will be compared with the Ra estimated without our device to quantify the effectiveness of our device to delay and reduce PPG level. Additionally, we can constrain our model to achieve an ideal Ra and solve for the parameters such as promoter strength of the two devices.

Second Part: Modeling the rate of horizontal gene transfer

Horizontal gene transfer between our modified E. coli and indigenous gut flora is something we must address as a safety concern. The most rapid means of horizontal gene transfer in bacteria is through the shuttle of plasmids. Transfer of plasmids occurs at about 1*10^-9 (ml cell^-1 h^-1, ref). And the number of E. coli is decreasing (as determined by the growth assay). Thus the total number of transferred plasmid within one load could be modeled as an ODE. The number is calculated to be #, given the SacB could kill #% of the cells after 2 hrs.

Ideally, we could transform our modified E. coli with a circuit composed of a consensus E. coli promoter, GFP, a consensus ASF 361 promoter and RFP. If we measure the expression level of GFP and RFP in the E. coli and ASF 361 respectively and get distinct FU readings, we could use a flow cytofluorometer to find out the specific plasmid transfer rate of our modified E. coli to a representative of the indigenous gut flora. However, we did not have the time to complete this experiment.

University of Virginia iGEM

148 Gilmer Hall

485 McCormick Road

Charlottesville, Virginia 22904

United States of America

virginia.igem@gmail.com