What do you mean by Cori Cycling?
In this cycle, glucose released by peripheral tissues is metabolized to lactate, which is then resynthesized to glucose in the liver. This process is energy consuming because 6 ATP are required for synthesizing only 2 ATP. Therefore, if the tumor cells release more lactate, more energy will be wasted on the resynthesis of glucose. So, it is understood that the Cori Cycling could be one of the significant factors in the development of weight loss. We should always remember that one of the important and significant concerns in cancer patients is weight loss. Next, we shall discuss about the abnormalities caused in lipid and protein metabolism.
Many research reports have stated that the major portion of weight loss in cancer patients is mainly due to body fat depletion. These include: increased lipolytic (break down of fats) rates caused by decreased food intake, stimulation of lipolysis due to the stress response to illness and release of lipolytic factors produced by the tumor itself. Loss of body fat occurs when both lipolysis and fatty acid oxidation are increased. Elevated levels of lipid are not significant in cancer patients, but may occur in association with certain tumors. The rate of fat oxidation is found to be greater than the rate of carbohydrate oxidation in cancer patients who had lost weight significantly.
With regard to protein metabolism the following changes are observed.
1. The rates 0.1 whole body turnover increase.
2. Catabolic (breakdown) rates of muscle protein increase with advancing stages of disease leading to weight loss.
3. Decreased plasma branched - chain amino acids.
4. Skeletal muscle mass is reduced.
5. Albumin is the principal secretory protein of the liver. Its depletion is common in cancer and results in hypoalbuminemia.
6. Negative nitrogen balance occurs in spite of sufficient intake.