A Young Woman Collapsed and Died

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Lisa Sanders, Critically Ill. New York Times Magazine, Apr 30, 2017.
https://www.nytimes.com/2017/04/ ... n-and-vomiting.html

Excerpt in the window of print: A simple test indicated that her brain was not working, even at the most basic level.

Note:
(a) "The stretcher carrying the 19-year-old woman was hurried into the emergency department of Banner University Medical Center in Tucson, Ariz. Her breath [air] moved in and out erratically."

Banner University Medical Center Tucson
https://en.wikipedia.org/wiki/Ba ... dical_Center_Tucson
founded in 1971, had been public until acquired in 2015 by private Banner Health and became private)
(b) "The liver donor [ie, the female college student who just died] had been born with a genetic defect. She was missing the genes that made a chemical called ornithine transcarbamylase (OTC) — a vital enzyme whose job is to help the liver break down proteins."

(c) Patricia A Wright, Nitrogen Excretion: Three End Products, Many Physiological Roles. J Exp Biol 198: 273-281 (1995; review)
https://pdfs.semanticscholar.org ... 91730c86452eac4.pdf

Read only the first 1 ¼ pages.

* See also metabolic waste
https://en.wikipedia.org/wiki/Metabolic_waste(section 1 Nitrogen wastes)

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(d) Hereafter I only deals with humans.
(i) Excretion and the liver. London: Royal Society of Chemistry, undated.
http://www.rsc.org/Education/Teachers/Resources/cfb/excretion.htm

Quote: "The body is unable to store proteins or amino acids, the metabolites of proteins. When excessive amounts of protein are ingested, the excess amino acids produced from digesting proteins are transported to the liver from the small intestine. * * * the amine group [also known as 'amino group' -- the term I have used perhaps because Taiwan has used American textbooks], -NH2, and a hydrogen atom, H, are removed from the main structure of the amino acid. The important product of this reaction is ammonia. The amine group is reduced to ammonia by the addition of a hydrogen atom. This process is called deamination. The non-nitrogenous portion of the molecule is converted to carbohydrates or fats."

(ii) Sandra Alters, Biology; Understanding life. Midwest Book Review, 2003, at page 245
https://books.google.com/books?i ... a%20%25&f=false
("nitrogenous waste, are produced from the breakdown of proteins and nucleic acids (DNA and RNA). * * * approximately 90% of all nitrogenous wastes are eliminated from the human body in the form of urea. Two other nitrogenous wastes found in the urine are uric acid and creatinine. Uric acid is formed from breakdown nucleic acids found in the cells of the food you eat and from the metabolic turnover of your nucleic acids and adenosine triphosphate (ATP). Creatinine is derived primarily from a nitrogen-containing molecule called creatine found in muscle cells")
(A) The nitrogen atom found in "nucleic acid" is, more specific, in purine
https://en.wikipedia.org/wiki/Purine
(view chemical structure only)
AND
Pyrimidine.
https://en.wikipedia.org/wiki/Pyrimidine
(B) In humans, uric acid is nitrogenous waste from degradation of purine and pyrimidines -- NOT proteins.
(C) "Uric acid is formed from breakdown nucleic acids found in the cells of the food you eat * * * "  

That is why it is foolish, from biological point of view, to eat organs packed with cells (eg, kidney, lungs, testes, placenta). Uric acid production will increase, which in some people may trigger gout 痛风.
(iii) Jose H Salazar, Overview of Urea and Creatinine. Lab Med., 45:e19-e20 (2014)
www.medscape.com/viewarticle/823420
("Urea accounts for the majority (up to 80%–90%) of the NPNs ['non-protein nitrogenous' waste] excreted by the body. * * * Creatinine, also a NPN waste product")

gives you a sense of importance of urea.
(iv) creatine→ creatinine
(A) function:

Creatine. In Medical Reference Guide> Supplement. University of Maryland, undated
www.umm.edu/health/medical/altmed/supplement/creatine
("Creatine is a naturally-occurring amino acid (protein building block [this is wrong; creatine is an amino acid, but does not from proteins] ) that's found in meat and fish, and also made by the human body in the liver, kidneys, and pancreas. It is converted into creatine phosphate or phosphocreatine and stored in the muscles, where it is used for energy. During high-intensity, short-duration exercise, such as lifting weights or sprinting, phosphocreatine is converted into ATP, a major source of energy within the human body.  Creatine supplements are popular among body builders and competitive athletes. It is estimated that Americans spend roughly $14 million per year on creatine supplement")

creatine
https://en.wikipedia.org/wiki/Creatine
(section 2 Phosphocreatine system)
(B) creatinine
https://en.wikipedia.org/wiki/Creatinine
(from Greek kreas flesh; chemical structure)

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(e) Ammonia is converted to less-toxic urea.
(i) urea cycle
https://en.wikipedia.org/wiki/Urea_cycle
(the first metabolic cycle to be discovered (Hans Krebs and Kurt Henseleit, 1932), five years before the discovery of the TCA cycle;

View the urea cycle in section 2 Reactions, where the square represents a mitochondrion. Pay attention to the enzyme OTC (ornithine transcarbamoylase) in the cycle.
(ii) Incidentally the clinical test for kidney functions with BUN (blood urea nitrogen) and creatinine.  (Though this foregoing topic has nothing to do with the case at the top, it tells you abot medical practice.).

Dinesh Puri, Textbook of Medical Biochemistry. 3rd ed. Elsevier (2001) at page 695
https://books.google.com/books?i ... 20waste&f=false
(Read section "B. Glomerular Function Tests[: serum urea, urea creatinine, and clearance test] creatinine is a nearly ideal substance for the measurement of clearance for various reasons")

(f) At last.
(i) Urea Cycle Disorders Overview. National Center for Biotechnology Information (NCBI), US National Library of Medicine, 2015
https://www.ncbi.nlm.nih.gov/books/NBK1217/
(ii) In liver failure (acute or chronic; all causes), ammonia plays a major role in hepatic encephalopathy. If you do not understand the term, it is alright.