The conversion of glucose to glycogen, a process of energy storage, is achieved by a number of enzymes, the absence or deficiency of which leads to the GSDs resulting in inborn errors of glycogen metabolism. These disorders arise due to deficiency of enzymes involved in the glyconeogenesis or due to abnormal functioning of the glycogen breakdown enzymes.
GSDs are categorized based on the type enzyme deficiency and the tissue affected. The systems involved in glycogen synthesis disorders are the liver and muscle, which are the primary sites of energy storage.
GSD Type IV, also known as amylopectinosis, is usually fatal and leads to death by age 4. Some of the clinical symptoms include hepatomegaly, failure to thrive, splenomegaly, cirrhosis and lumbar lordosis.
Type IV disorder arises due to deficiency of the glycogen branching enzyme amylo-1,4-1,6 transglucosidase, which leads to the formation of abnormally structured glycogen, having amylase molecules with low solubility, leading to glycogen precipitation in the liver, the heart and other tissues. The condition ultimately leads to early death (Ozen, 2541-53).
Type I diabetic patients who are erroneously prescribed too high of an insulin dose in their insulin regimen can present liver disease symptoms similar to those presented in glycogen storage diseases. Explain the biochemical basis for this finding.
One of the important functions of insulin is glycogen syn...
Insulin regulates the amount of glucose absorbed or released from the cell. The glucose absorbed from the blood is stored in the form of glycogen in the liver.
One of the important functions of insulin is glycogen synthesis, brought about by activating the enzyme hexokinase. This in turn, phosphorylates glucose, thus, trapping it within the cell, in the form of energy.
Insulin also inhibit the activity of glucose-6-phosphatase and activates phosphofructokinase and glycogen synthase, thus helping the hepatocytes to havest excess glucose in the form of glycogen.
But, in the absense of insulin, as in case of type 1 diabetes, glucose circulation in the blood increases and the cells fail to harvest it for energy. In the absence of energy the cells activate the enzymes involved in the breakdown of glycogen (glycogenolysis).Under the conditions of cell starvation triggered by lack of insulin, glucagon, a counter regulatory hormone,is activated, which, again stimulates the process of glycogenolysis in hepatocytes, thus releasing energy.
When insulin is administered from an outside source, in excess, (eg: injections), insulin activates the formation of glycogen from glucose and inhibition glycogenolysis. Therefore, in presence of excess insulin, there is a surplus production of glycogen, similar to that of glycogen storage disorders. Also, there is inhibition of glucose-6-phosphate, similar to deficiency of the same as in glycogen storage disorders (Bowen).
3.Helicobacter pylori is a bacterium that colonizes the upper gastrointestinal tract in humans and is the causative agent of chronic gastritis, ulcers, and possibly gastric cancer. Knowledge of the intermediary metabolism of this organism would be helpful in developing effective drug