1. In the “arginine metabolism, nitric oxide metabolism, and cell death” section
ID: 3518728 • Letter: 1
Question
1. In the “arginine metabolism, nitric oxide metabolism, and cell death” section of the results and discussion section the authors wrote “The combination of elevated urea and creatinine could also suggest renal dysfunction, consistent with the proteinosis observed in the renal histopathology as reported in the companion study.” Why does elevated urea suggest renal dysfunction? (1 point)
2. In the “TCA cycle intermediates and energetics” section of the results and discussion section the authors wrote “By 24-48 hours, TCA metabolites in the plasma were no longer significantly elevated, suggesting restoration of the TCA cycle to homeostasis.” Is end of this sentence positive feedback or negative feedback? (1 point)
3. How do you know that your answer to question 6 is correct? In other words, what word or words in the quote of question 2 suggests that your answer to question 2 is correct? (1 point)
4. In the “Co-factor metabolism” section of the results and discussion section the authors wrote “Pyridoxal levels were increased in heated animals relative to controls at Tc,MAX, possibly due to increased catabolism.” Where do you think pyridoxal was prior to being increased? (1 point)
5. In the “Co-factor metabolism” section of the results and discussion section the authors wrote “In contrast, pyridoxal and pyridoxate levels were lower than control at 24048 hours, possibly due to increased anabolism (a process that requires B6 as a cofactor) and returns to homeostasis.” What do you think happened to pyridoxal and pyridoxate based on this sentence? (1 point)
*reference*
* https://bmcphysiol.biomedcentral.com/articles/10.1186/s12899-014-0014-0
Explanation / Answer
1. If the urea levels are elevated, the condition is called uremia. Urmia is when there is more urea present in blood. Since the function of kidneys is to remove urea from blood, presence of high levels of urea indicates renal dysfunction.
2. It is negative feedback because the TCA metabolites in plasma are reduced through feedback. Since it reduces the quantity, it is an example of negative feedback.
3. "TCA metabolites in plasma were no longer significantly elevated,s suggesting restoration of the TCA cycle to homeostasis" . Here the word "restoration" implies that the quantity is reduces. Hence it is negative feedback.
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