Once you've finished gorging yourself on turkey and pie and have decided to burn off that extra "fuel" by shopping non-stop (as an aerobic workout) on Black Friday morning, remember that you have your cells' mitochondria to thank [1].
The mitochondria house the enzymes and conditions necessary for aerobic respiration via the citric acid cycle [1p761-2]. Just a couple of turns of the cycle and the food you eat can give you double the energy than what the cell can produce under anaerobic conditions of glycolysis and the pyruvate dehydrogenase complex [1p761-2].
But the citric acid cycle also does so much more. In the same oxygen-requiring breath of turns, the citric acid cycle makes up molecular precursors or "building blocks" needed by the body [2]. Like glycolysis this role gives the citric acid cycle amphibolic status that includues both catabolism of food and anabolism, or biosynthesis [1p770].
In fact, we owe the citric acid cycle thanks for biosynthesizing non-essential amino acids [1p770]. When the body runs low on one of these, the cell uses the carbon skeletons of citric acid cycle intermediates to produce them again [1p770]. Two intermediates used are:
- Oxaloacetate, in conjunction with glutamate, for the production of aspartate via a transamination reaction—where an enzyme catalyzes the transfer of an alpha-amino group to an alpha-ketoic acid [1p770].
- Alpha-ketoglutarate, in conjunction with ammonium and reduced by NADPH, produces glutamate, which is used to produce glutamine, proline and arginine [1p770].
These amino acids are then used for production of various essential proteins including enzymes and for building body tissues [1p596-7]. Other anabolic building blocks of the citric acid cycle include citrate for creating fatty acids and cholesterol, succinyl-CoA for heme, malate for producing pyruvate, and oxaloacetate for producing glucose [2].
Although the citric acid cycle is also found in bacteria [2], the mitochondria's efficient amphibolic role made its inclusion as part of eukaryotic cells an essential step in the evolution of multi-celled organisms [1p746]. Because mitochondria have their own mtDNA and grow and multiply like bacteria, they are thought to have descended of bacteria captured in eukaryotic cells millions of years ago [1p746].
Genetic research reveals the capture happened only once because all mitochondria can be traced back to one alpha-proteobacterial ancestor [3] and humans one Mitochondrial Eve [4]. As more is learned about that day of capture of our Mitochondrial Eve, we might also find it to be a true day for celebration and to express gratitude.
References
1. Denniston KJ, Topping JJ, Caret RL. General, Organic, And Biochemistry, 5th ed. New York: McGraw Hill; 2007.
2. Wiley. The citric acid cycle [animation]. Available at http://www.wiley.com/college/pratt/0471393878/student/animations/citric_acid_cycle/index.html. Accessed November 28, 2008.
3. Gray MW, Burger G, Lang BF. The origin and early evolution of mitochondria. Genome Biol. 2001; 2(6): reviews1018.1–reviews1018.5. Available at: http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=138944. Accessed on November 28, 2008.
4. Cann RL, Stoneking M, Wilson AC. Nature. 1987 January;325:31-36. Available at http://www.nature.com/nature/ancestor/pdf/325031.pdf. Accessed on November 28, 2008.
Sunday, November 30, 2008
Wednesday, November 26, 2008
Incredible, edible egg but so high in cholesterol
If it wasn't for its high content of cholesterol, egg yolks would be regarded more strongly as one of nature's health powerhouses [1]. And, if regularly eaten, the egg would go a long way of ensuring against different nutritional deficiencies [1].
Hope has come for a more incredible, edible egg...
If soluble fiber and red yeast rice works on humans to lower cholesterol, why not chickens? They do. Soluble fiber has been shown to significantly impact the amount of total cholesterol in eggs [2]. And a study in China revealed that chickens fed red yeast rice produced egg yolks with significantly less triglycerides and LDL cholesterol [3].
In addition, eggs fortified with omega-3 oils are now a popular marketplace novelty and a welcome approach. Although omega-3 fortification won't change egg cholesterol content, it may help improve its profile for heart health [4].
Contrary to popular opinion, switching to quail eggs would not be beneficial since their cholesterol content is similar to that of chicken eggs [5].
1. Nutrition Data. Available at: http://www.nutritiondata.com/facts/dairy-and-egg-products/113/2. Accessed on November 26, 2008.
2. McNaughton JL. Effect of Dietary Fiber on Egg Yolk, Liver, and Plasma Cholesterol Concentrations of the Laying Hen. J Nutr. Available at: http://jn.nutrition.org/cgi/content/abstract/108/11/1842. Accessed on November 26, 2008.
3. Wang J, Pan T. Effect of red mold rice supplements on serum and egg yolk cholesterol levels of laying hens. Available at: http://cat.inist.fr/?aModele=afficheN&cpsidt=150059352. Accessed on November 26, 2008.
4. Manitoba Agriculture and Rural Initiatives. Increasing Omega-3 Fatty Acids in Eggs from Small Chicken Flocks. Avaialable at: http://www.gov.mb.ca/agriculture/livestock/poultry/bba01s04.html. Accessed on November 26, 2008.
5. Bragagnolo N, Rodriguez-Amaya DB. Comparison of the cholesterol content of Brazilian chicken and quail eggs. J Food Comp Anal. Available at: http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WJH-48B5K4K-1&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=beb35c37292ad81fe9a7e2e94bc9b859. Accessed on November 25, 2008.
Hope has come for a more incredible, edible egg...
If soluble fiber and red yeast rice works on humans to lower cholesterol, why not chickens? They do. Soluble fiber has been shown to significantly impact the amount of total cholesterol in eggs [2]. And a study in China revealed that chickens fed red yeast rice produced egg yolks with significantly less triglycerides and LDL cholesterol [3].
In addition, eggs fortified with omega-3 oils are now a popular marketplace novelty and a welcome approach. Although omega-3 fortification won't change egg cholesterol content, it may help improve its profile for heart health [4].
Contrary to popular opinion, switching to quail eggs would not be beneficial since their cholesterol content is similar to that of chicken eggs [5].
1. Nutrition Data. Available at: http://www.nutritiondata.com/facts/dairy-and-egg-products/113/2. Accessed on November 26, 2008.
2. McNaughton JL. Effect of Dietary Fiber on Egg Yolk, Liver, and Plasma Cholesterol Concentrations of the Laying Hen. J Nutr. Available at: http://jn.nutrition.org/cgi/content/abstract/108/11/1842. Accessed on November 26, 2008.
3. Wang J, Pan T. Effect of red mold rice supplements on serum and egg yolk cholesterol levels of laying hens. Available at: http://cat.inist.fr/?aModele=afficheN&cpsidt=150059352. Accessed on November 26, 2008.
4. Manitoba Agriculture and Rural Initiatives. Increasing Omega-3 Fatty Acids in Eggs from Small Chicken Flocks. Avaialable at: http://www.gov.mb.ca/agriculture/livestock/poultry/bba01s04.html. Accessed on November 26, 2008.
5. Bragagnolo N, Rodriguez-Amaya DB. Comparison of the cholesterol content of Brazilian chicken and quail eggs. J Food Comp Anal. Available at: http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WJH-48B5K4K-1&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=beb35c37292ad81fe9a7e2e94bc9b859. Accessed on November 25, 2008.
When cholesterol starts creeping up past 200
When total cholesterol begins to creep up past 200 mg/dL, it's time to change diet [1]. If it reaches 240 mg/dL or higher, then the body is at high risk of coronary artery disease and cardiac death [1]. The risk is only accentuated if LDL cholesterol is higher than 160 mg/dL and HDL cholesterol is lower than 40 mg/dL (50 for women) [1].
So, what can be done? Takng cholestyramine and colestipol will help promote excretion of bile [2]. The "statins" atorvastatin, lovastatin and simvastatin can block key enzymes that synthesize cholesterol [2]. Even niacin in the form of nicotinic acid can help through its effects on widening blood vessels [3]. But the benefits of these drugs and the vitamin are extremely limited, because if treatment is stopped, cholesterol can and probably will go back up again unless there is a change of diet [4]. The drugs can also have possible side effects such as liver damage, muscle pain and break down, and kidney problems [4].
A change in diet and lifestyle is most important. Regular exercise, particularly aerobic exercise, increases HDL cholesterol, which in turn helps to lower total cholesterol and LDL cholesterol [5]. In addition, according to Mayo Clinic, the top five foods for lowering cholesterol are oat bran (soluble fiber), nuts, fish oil, olive oil, and plant sterols [6]. Soluble fiber included with meals may reduce absorption of cholesterol, nuts like walntus and almonds can replace high-saturated fat and high-cholesterol foods because their lipid profile includes PUFAs, fish helps to lower TGs through its content of omega-3 oils, olive oil PUFAs and antioxidants help (avoid lite olive oil), and plant sterols block absorption of cholesterol [6].
References
1. Mayo Clinic. Cholesterol levels: What numbers should you aim for? Available at: http://www.mayoclinic.com/health/cholesterol-levels/CL00001. Accessed on November 25, 2008.
2. Tortora GJ, Derrickson B. Principles of Anatomy and Physiology, 11th ed; 2006. New York: John Wiley & Sons.
3. Grundy SM, Mok HY, Zech L, Berman M. Influence of nicotinic acid on metabolism of cholesterol and triglycerides. Available at: http://www.jlr.org/cgi/content/abstract/22/1/24. Accessed on November 25, 2008.
4. Mayo Clinic.Statins: Are these cholesterol-lowering drugs right for you? Available at: http://www.mayoclinic.com/health/statins/CL00010. Accessed on November 25, 2008.
5. Stein RA, Michielli DW, Glantz MD, Sardy H, Cohen A, Goldberg N, Brown CD. Effects of different exercise training intensities on lipoprotein cholesterol fractions in healthy middle-aged men. Am Heart J.1990 Feb; 119(2 Pt 1): 277-83. Available at: http://grande.nal.usda.gov/ibids/index.php?mode2=detail&origin=ibids_references&therow=282138. Accessed on November 25, 2008.
6. Mayo Clinic. Cholesterol: The top 5 foods to lower your numbers. Available at: http://www.mayoclinic.com/health/cholesterol/CL00002. Accessed on November 25, 2008.
So, what can be done? Takng cholestyramine and colestipol will help promote excretion of bile [2]. The "statins" atorvastatin, lovastatin and simvastatin can block key enzymes that synthesize cholesterol [2]. Even niacin in the form of nicotinic acid can help through its effects on widening blood vessels [3]. But the benefits of these drugs and the vitamin are extremely limited, because if treatment is stopped, cholesterol can and probably will go back up again unless there is a change of diet [4]. The drugs can also have possible side effects such as liver damage, muscle pain and break down, and kidney problems [4].
A change in diet and lifestyle is most important. Regular exercise, particularly aerobic exercise, increases HDL cholesterol, which in turn helps to lower total cholesterol and LDL cholesterol [5]. In addition, according to Mayo Clinic, the top five foods for lowering cholesterol are oat bran (soluble fiber), nuts, fish oil, olive oil, and plant sterols [6]. Soluble fiber included with meals may reduce absorption of cholesterol, nuts like walntus and almonds can replace high-saturated fat and high-cholesterol foods because their lipid profile includes PUFAs, fish helps to lower TGs through its content of omega-3 oils, olive oil PUFAs and antioxidants help (avoid lite olive oil), and plant sterols block absorption of cholesterol [6].
References
1. Mayo Clinic. Cholesterol levels: What numbers should you aim for? Available at: http://www.mayoclinic.com/health/cholesterol-levels/CL00001. Accessed on November 25, 2008.
2. Tortora GJ, Derrickson B. Principles of Anatomy and Physiology, 11th ed; 2006. New York: John Wiley & Sons.
3. Grundy SM, Mok HY, Zech L, Berman M. Influence of nicotinic acid on metabolism of cholesterol and triglycerides. Available at: http://www.jlr.org/cgi/content/abstract/22/1/24. Accessed on November 25, 2008.
4. Mayo Clinic.Statins: Are these cholesterol-lowering drugs right for you? Available at: http://www.mayoclinic.com/health/statins/CL00010. Accessed on November 25, 2008.
5. Stein RA, Michielli DW, Glantz MD, Sardy H, Cohen A, Goldberg N, Brown CD. Effects of different exercise training intensities on lipoprotein cholesterol fractions in healthy middle-aged men. Am Heart J.1990 Feb; 119(2 Pt 1): 277-83. Available at: http://grande.nal.usda.gov/ibids/index.php?mode2=detail&origin=ibids_references&therow=282138. Accessed on November 25, 2008.
6. Mayo Clinic. Cholesterol: The top 5 foods to lower your numbers. Available at: http://www.mayoclinic.com/health/cholesterol/CL00002. Accessed on November 25, 2008.
Saturday, November 22, 2008
When you're full of dirty, hot air.
You could be a politician or you could have emphysema. The disorder usually is due to years of irritation from cigarette smoke, but anyone could get emphysema if exposed to years of air pollution or exposure to industrial dust [1p887].
The long-term irritation and resulting inflammation damages or destroys the walls of air sacs in the lungs [2]. The loss of elasticity causes bronchioles to collapse and air becomes trapped in the air sacs, over-stretching them and not allowing full ability to exhale [2]. The air sacs can rupture and the lung is left with abnormally large air spaces that stay filled with air [2].
Oxygen diffusion across the respiratory membrane is also reduced due to less surface area for gas exchange [1p887]. This limits the amount of oxygen in the blood and can result in leaving a person breathless even during mild exercise [1p887]. Symptoms are coughing, loss of appetite as well as fatigue [2].
Excessive mucus and inactivity of cilia–eventually allow irritants to damage the alveolar tissue, which can end up allowing squamous cancer cells to spread into the lower respiratory tract [3].
It's worth noting that oxygen therapy is one of the few therapies actually proven to keep those with emphysema living longer and with a better quality of life [4]. If you know anyone with emphysema, let them know. Oxygen therapy at night can be especially beneficial [4]. And if the patient doesn't exercise, all the more reason.
Three out of four adults with alpha-1 antitrypsin deficiency (AAT), a genetic disorder, will also get emphysema. Since the liver makes the protein and releases it into the blood stream it only takes a blood test to find out if you have AAT deficiency.
References
1. Tortora, GJ, Derrickson, B. Principles of Anatomy and Physiology, 11th ed; 2006. New York: John Wiley & Sons.
2. Mayo Foundation for Medical Education and Research. Emphysema and Smoking. Available at http://emphysema.org/.
3. http://www.pul.unimaas.nl/respir.htm
4. http://www.nslij.com/body.cfm?id=5987
5. http://www.nlm.nih.gov/medlineplus/alpha1antitrypsindeficiency.html
The long-term irritation and resulting inflammation damages or destroys the walls of air sacs in the lungs [2]. The loss of elasticity causes bronchioles to collapse and air becomes trapped in the air sacs, over-stretching them and not allowing full ability to exhale [2]. The air sacs can rupture and the lung is left with abnormally large air spaces that stay filled with air [2].
Oxygen diffusion across the respiratory membrane is also reduced due to less surface area for gas exchange [1p887]. This limits the amount of oxygen in the blood and can result in leaving a person breathless even during mild exercise [1p887]. Symptoms are coughing, loss of appetite as well as fatigue [2].
Excessive mucus and inactivity of cilia–eventually allow irritants to damage the alveolar tissue, which can end up allowing squamous cancer cells to spread into the lower respiratory tract [3].
It's worth noting that oxygen therapy is one of the few therapies actually proven to keep those with emphysema living longer and with a better quality of life [4]. If you know anyone with emphysema, let them know. Oxygen therapy at night can be especially beneficial [4]. And if the patient doesn't exercise, all the more reason.
Three out of four adults with alpha-1 antitrypsin deficiency (AAT), a genetic disorder, will also get emphysema. Since the liver makes the protein and releases it into the blood stream it only takes a blood test to find out if you have AAT deficiency.
References
1. Tortora, GJ, Derrickson, B. Principles of Anatomy and Physiology, 11th ed; 2006. New York: John Wiley & Sons.
2. Mayo Foundation for Medical Education and Research. Emphysema and Smoking. Available at http://emphysema.org/.
3. http://www.pul.unimaas.nl/respir.htm
4. http://www.nslij.com/body.cfm?id=5987
5. http://www.nlm.nih.gov/medlineplus/alpha1antitrypsindeficiency.html
Bad case of heartburn
After a large meal and red wine some of the stomach acid produced can flow back into the esophagus due to a relaxed or weakened sphincter [1]. Lying down on the couch is a bad idea since it probably would make the acid backup worse [2].
The resulting heartburn causes the primary symptoms, which is a burning pain in the chest under the breastbone [2]. Heartburn can happen occasionally to almost anyone, but if the symptoms become frequent, then the heartburn may be related to gastroesophageal reflux disease [2].
You can drink some baking soda mixed with cream of tartar and water as a temporary measure, then think about changing your diet to smaller meals and losing some fat [2].
Home remedies might help. Digestive enzymes help to get the digestive process moving more quickly. Increasing fiber absorbs acid and gas. Tea soothes the stomach and gets things going. You can also try ginger.
1. Tortora, GJ, Derrickson, B. Principles of Anatomy and Physiology, 11th ed; 2006. New York: John Wiley & Sons.
2. Mayo Clinic. Heartburn. Available at: http://www.mayoclinic.com/health/heartburn-gerd/DS00095. Accessed on November 22, 2008.
The resulting heartburn causes the primary symptoms, which is a burning pain in the chest under the breastbone [2]. Heartburn can happen occasionally to almost anyone, but if the symptoms become frequent, then the heartburn may be related to gastroesophageal reflux disease [2].
You can drink some baking soda mixed with cream of tartar and water as a temporary measure, then think about changing your diet to smaller meals and losing some fat [2].
Home remedies might help. Digestive enzymes help to get the digestive process moving more quickly. Increasing fiber absorbs acid and gas. Tea soothes the stomach and gets things going. You can also try ginger.
1. Tortora, GJ, Derrickson, B. Principles of Anatomy and Physiology, 11th ed; 2006. New York: John Wiley & Sons.
2. Mayo Clinic. Heartburn. Available at: http://www.mayoclinic.com/health/heartburn-gerd/DS00095. Accessed on November 22, 2008.
I'll have a tall glass of fresh-squeezed fructose
Orange juice delivers a potent dose of what is roughly half glucose and half fructose [1].
Glucose, we know, is the simple sugar that serves as the primary source of fuel to the blood, brain and muscle [2p735]. Its intake stimulates the release of insulin, goes through glycolysis to create energy, and is used to synthesize of glycogen for storage [2p735].
Fructose does not stimulate the release of insulin, nor does it enter glycolysis in the same way as glucose [3]. In fact it enters glycolysis a few steps later after going through its own metabolism. After being transported to the liver, fructose is phosphorylated by fructokinase to form fructose 1-phosphate, then by aldolase B to dihydroxyacetone phosphate and glyceraldehyde [3p58]. Glyceraldehyde is phosphorylated to glyceraldehydde 3-phosphate, and this molecule along with dihydroxyacetone enter glycolysis [3p58]. In the muscle, fructose is phosphorylated by hexokinase to fructose 6-phosphate, which is then used for glycogenesis or glycolysis [3p358].
Apart from being famous for being sweeter than glucose and the disaccharide sucrose (of which fructose is half part of), would the low-glycemic "fruit sugar" be better for the body since it create less of an insulin response? Science says "probably not."
In fact, high consumption of fructose is now being blamed for type 2 diabetes. The influx of fructose to the liver from soda with high-fructose corn syrup is found to interfere with glucose metabolism through metabolic dyslipidemia, a disturbance that may induce insulin resistance [4]. You get extra lipogenesis from fructose. Fructose by-passes the conversion of glucose 6-phosphate to fructose 1,6-phosphate. This is glycolysis's main regulatory step. Fructose, then, is "unregulated" and able to "uncontrollably" over-produce triglycerides. Evidence is now showing that the diabetes and obesity, which have become modern-day epidemics, could be prevented through significant reduction of fructose in the diet [4].
Research is also showing fructose may be more detrimental than glucose in high amounts. A study at the University of California on overweight or obese adults who were given beverages sweetened with fructose or glucose showed that those drinking the beverage with fructose gained pounds and had higher triglycerides and higher serum LDL cholesterol levels [5].
References
1. Ghanim H, Mohanty P, Pathak R, Chaudhuri A, Sia CL, Dandona P. Orange juice or fructose intake does not induce oxidative and inflammatory response. Available at:
http://care.diabetesjournals.org/cgi/content/abstract/30/6/1406. Accessed on November 20, 2008.
2. Denniston KJ, Topping JJ, Caret RL. General, Organic, And Biochemistry, 5th ed. New York: McGraw Hill; 2007.
3. Salway JG. Medical biochemistry at a glance, 2nd ed. 2006; Malden, Mass: Blackwell Publishing. (excellent book!!)
4. Basciano H, Federico L, Khosrow A. Fructose, insulin resistance and metabolic dyslipidemia. Nutrition & Metabolism. Available at: http://www.nutritionandmetabolism.com/content/2/1/5. Accessed on November 22, 2008.
5. DeNoon DJ. Study: Fructose increases heart risk factors and weight. WebMD Health News. Available at: http://www.medicinenet.com/script/main/art.asp?articlekey=82117. Accessed on November 20, 2008.
Glucose, we know, is the simple sugar that serves as the primary source of fuel to the blood, brain and muscle [2p735]. Its intake stimulates the release of insulin, goes through glycolysis to create energy, and is used to synthesize of glycogen for storage [2p735].
Fructose does not stimulate the release of insulin, nor does it enter glycolysis in the same way as glucose [3]. In fact it enters glycolysis a few steps later after going through its own metabolism. After being transported to the liver, fructose is phosphorylated by fructokinase to form fructose 1-phosphate, then by aldolase B to dihydroxyacetone phosphate and glyceraldehyde [3p58]. Glyceraldehyde is phosphorylated to glyceraldehydde 3-phosphate, and this molecule along with dihydroxyacetone enter glycolysis [3p58]. In the muscle, fructose is phosphorylated by hexokinase to fructose 6-phosphate, which is then used for glycogenesis or glycolysis [3p358].
Apart from being famous for being sweeter than glucose and the disaccharide sucrose (of which fructose is half part of), would the low-glycemic "fruit sugar" be better for the body since it create less of an insulin response? Science says "probably not."
In fact, high consumption of fructose is now being blamed for type 2 diabetes. The influx of fructose to the liver from soda with high-fructose corn syrup is found to interfere with glucose metabolism through metabolic dyslipidemia, a disturbance that may induce insulin resistance [4]. You get extra lipogenesis from fructose. Fructose by-passes the conversion of glucose 6-phosphate to fructose 1,6-phosphate. This is glycolysis's main regulatory step. Fructose, then, is "unregulated" and able to "uncontrollably" over-produce triglycerides. Evidence is now showing that the diabetes and obesity, which have become modern-day epidemics, could be prevented through significant reduction of fructose in the diet [4].
Research is also showing fructose may be more detrimental than glucose in high amounts. A study at the University of California on overweight or obese adults who were given beverages sweetened with fructose or glucose showed that those drinking the beverage with fructose gained pounds and had higher triglycerides and higher serum LDL cholesterol levels [5].
References
1. Ghanim H, Mohanty P, Pathak R, Chaudhuri A, Sia CL, Dandona P. Orange juice or fructose intake does not induce oxidative and inflammatory response. Available at:
http://care.diabetesjournals.org/cgi/content/abstract/30/6/1406. Accessed on November 20, 2008.
2. Denniston KJ, Topping JJ, Caret RL. General, Organic, And Biochemistry, 5th ed. New York: McGraw Hill; 2007.
3. Salway JG. Medical biochemistry at a glance, 2nd ed. 2006; Malden, Mass: Blackwell Publishing. (excellent book!!)
4. Basciano H, Federico L, Khosrow A. Fructose, insulin resistance and metabolic dyslipidemia. Nutrition & Metabolism. Available at: http://www.nutritionandmetabolism.com/content/2/1/5. Accessed on November 22, 2008.
5. DeNoon DJ. Study: Fructose increases heart risk factors and weight. WebMD Health News. Available at: http://www.medicinenet.com/script/main/art.asp?articlekey=82117. Accessed on November 20, 2008.
Friday, November 21, 2008
When you can't degrade glycogen
Your brain, blood and muscles depend almost entirely on dietary glucose as a fuel source so your body must store the sugar for continual supply [1p733]. If you go without eating for a while or jog a mile or two you’ll find yourself relying on glycogen for energy [1p733]. The long-branched glucose polymer acts as a store of glucose molecules, ready for the moment’s need [1p733]. But imagine having inherited a defective gene that resulted in not allowing your body to degrade glycogen stores.
If it wasn’t for Mendelian genetics, von Gierke’s disease may never have been completely understood [2]. Also called type 1 glycogen storage disease, the inherited disorder was found in 1952 using Mendel’s principles to result from a defective gene that causes the lack of glucose-6-phosphate [2 & 1p740]. The enzyme is necessary for catalyzing the final step in gluconeogenesis and glycogenolysis, which is needed for synthesis of glucose from noncarbohydrates precursors and removal of glucose from glycogen when blood glucose levels are low [1p740].
Without an ability to degrade glycogen, those with the disease suffer from low blood sugar between meals that can reach dangerous levels, and excessive accumulation of glycogen in the liver, muscle and in the tubules of the kidneys that can create further health complications [1p740 & 3]. Symptoms include an enlarged liver; puffy cheeks and limbs; a swollen belly; constant hunger; stunted growth; delayed or underdeveloped puberty, gout, easy bruising and nosebleeds, fatigue, and irritability [3].
Living with von Gierke’s disease requires avoiding low blood sugar through frequent meals that include carbohydrates and feeding tubes used at night [3]. Because lactose and fructose can’t be broken down properly, milk and fruits are usually avoided [3].
References
1. Denniston KJ, Topping JJ, Caret RL. General, Organic, And Biochemistry, 5th ed. New York: McGraw Hill; 2007.
2. Lorentz CP, Wieben ED, Tefferi A, Whiteman D, Dewald G. Primer on medical genomics part I: History of genetics and sequencing of the human genome. Mayo Clin Proc. 2002;77:773-782. Available at: http://www.mayoclinicproceedings.com/inside.asp?AID=165&UID=. Accessed on November 19, 2008.
2. MedlinePlus. Von Gierke disease. Medical Encyclopedia. Available at: http://www.nlm.nih.gov/medlineplus/ency/article/000338.htm. November 19, 2008.
If it wasn’t for Mendelian genetics, von Gierke’s disease may never have been completely understood [2]. Also called type 1 glycogen storage disease, the inherited disorder was found in 1952 using Mendel’s principles to result from a defective gene that causes the lack of glucose-6-phosphate [2 & 1p740]. The enzyme is necessary for catalyzing the final step in gluconeogenesis and glycogenolysis, which is needed for synthesis of glucose from noncarbohydrates precursors and removal of glucose from glycogen when blood glucose levels are low [1p740].
Without an ability to degrade glycogen, those with the disease suffer from low blood sugar between meals that can reach dangerous levels, and excessive accumulation of glycogen in the liver, muscle and in the tubules of the kidneys that can create further health complications [1p740 & 3]. Symptoms include an enlarged liver; puffy cheeks and limbs; a swollen belly; constant hunger; stunted growth; delayed or underdeveloped puberty, gout, easy bruising and nosebleeds, fatigue, and irritability [3].
Living with von Gierke’s disease requires avoiding low blood sugar through frequent meals that include carbohydrates and feeding tubes used at night [3]. Because lactose and fructose can’t be broken down properly, milk and fruits are usually avoided [3].
References
1. Denniston KJ, Topping JJ, Caret RL. General, Organic, And Biochemistry, 5th ed. New York: McGraw Hill; 2007.
2. Lorentz CP, Wieben ED, Tefferi A, Whiteman D, Dewald G. Primer on medical genomics part I: History of genetics and sequencing of the human genome. Mayo Clin Proc. 2002;77:773-782. Available at: http://www.mayoclinicproceedings.com/inside.asp?AID=165&UID=. Accessed on November 19, 2008.
2. MedlinePlus. Von Gierke disease. Medical Encyclopedia. Available at: http://www.nlm.nih.gov/medlineplus/ency/article/000338.htm. November 19, 2008.
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