#separator:Tab
#html:false
#tags column:5
IMF-090-03-0001-en	Why can excess PRPP formation increase uric-acid production?	PRPP activates amidophosphoribosyltransferase, so excess drives de novo purine synthesis and, in turn, uric-acid production.	Integrated Medical Foundations; chapter 90, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 0694dc90df0ccef97f481656b1de8e0cd5702df8e85ec52e98ba00ec91b97b40; editorial review pending	imf lang::en chapter::090 module::090-03 review::pending
IMF-090-03-0002-en	What architectural difference separates de novo purine and pyrimidine synthesis?	Purine rings are assembled stepwise directly on PRPP ribose, whereas the pyrimidine ring is built first and then attached to PRPP.	Integrated Medical Foundations; chapter 90, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 0694dc90df0ccef97f481656b1de8e0cd5702df8e85ec52e98ba00ec91b97b40; editorial review pending	imf lang::en chapter::090 module::090-03 review::pending
IMF-090-03-0003-en	How does the branching of inosine monophosphate help balance adenine and guanine nucleotide pools?	The AMP branch uses GTP and the GMP branch uses ATP, so each draws on the other's product, and end products feedback-inhibit their own branches.	Integrated Medical Foundations; chapter 90, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 0694dc90df0ccef97f481656b1de8e0cd5702df8e85ec52e98ba00ec91b97b40; editorial review pending	imf lang::en chapter::090 module::090-03 review::pending
IMF-090-03-0004-en	Why does a purine salvage enzyme defect cause both nucleotide shortage and excess purine degradation?	Salvage normally recycles free bases and restrains PRPP-driven de novo synthesis; when it fails, recycling is lost and purine degradation increases.	Integrated Medical Foundations; chapter 90, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 0694dc90df0ccef97f481656b1de8e0cd5702df8e85ec52e98ba00ec91b97b40; editorial review pending	imf lang::en chapter::090 module::090-03 review::pending
IMF-090-03-0005-en	What shows that the neurological disease of Lesch-Nyhan syndrome is not simply caused by urate?	It does not resolve when uric acid is lowered, indicating a tissue-specific purine-balance defect.	Integrated Medical Foundations; chapter 90, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 0694dc90df0ccef97f481656b1de8e0cd5702df8e85ec52e98ba00ec91b97b40; editorial review pending	imf lang::en chapter::090 module::090-03 review::pending
IMF-090-03-0006-en	What most commonly causes hyperuricaemia, and why is it not sufficient for gout?	Usually reduced renal excretion; monosodium urate crystals form only when supersaturation, temperature, pH, matrix and time permit nucleation.	Integrated Medical Foundations; chapter 90, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 0694dc90df0ccef97f481656b1de8e0cd5702df8e85ec52e98ba00ec91b97b40; editorial review pending	imf lang::en chapter::090 module::090-03 review::pending
IMF-090-03-0007-en	How does adenosine deaminase deficiency cause severe combined immunodeficiency?	Deoxyadenosine nucleotides accumulate and inhibit ribonucleotide reductase, injuring lymphocytes.	Integrated Medical Foundations; chapter 90, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 0694dc90df0ccef97f481656b1de8e0cd5702df8e85ec52e98ba00ec91b97b40; editorial review pending	imf lang::en chapter::090 module::090-03 review::pending
IMF-090-03-0008-en	How does carbamoyl-phosphate synthetase two differ from carbamoyl-phosphate synthetase one?	It is cytosolic, uses glutamine, and serves pyrimidine synthesis in a complex with aspartate transcarbamylase and dihydroorotase, differing in location, nitrogen source and regulation from the mitochondrial urea-cycle enzyme.	Integrated Medical Foundations; chapter 90, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 0694dc90df0ccef97f481656b1de8e0cd5702df8e85ec52e98ba00ec91b97b40; editorial review pending	imf lang::en chapter::090 module::090-03 review::pending
IMF-090-03-0009-en	How does the presence of hyperammonaemia distinguish hereditary orotic aciduria from ornithine-transcarbamylase deficiency?	UMP-synthase deficiency raises urinary orotate without hyperammonaemia, whereas in ornithine-transcarbamylase deficiency mitochondrial carbamoyl phosphate spills into the pyrimidine pathway alongside hyperammonaemia.	Integrated Medical Foundations; chapter 90, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 0694dc90df0ccef97f481656b1de8e0cd5702df8e85ec52e98ba00ec91b97b40; editorial review pending	imf lang::en chapter::090 module::090-03 review::pending
IMF-090-03-0010-en	Why can folinic acid rescue selected methotrexate toxicity?	Methotrexate inhibits human dihydrofolate reductase, and folinic acid bypasses that reduction step.	Integrated Medical Foundations; chapter 90, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 0694dc90df0ccef97f481656b1de8e0cd5702df8e85ec52e98ba00ec91b97b40; editorial review pending	imf lang::en chapter::090 module::090-03 review::pending
IMF-090-03-0011-en	Why does combining mercaptopurine with a xanthine-oxidase inhibitor risk severe toxicity?	Xanthine-oxidase inhibition changes mercaptopurine clearance, so severe toxicity can follow unless the dose is adjusted.	Integrated Medical Foundations; chapter 90, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 0694dc90df0ccef97f481656b1de8e0cd5702df8e85ec52e98ba00ec91b97b40; editorial review pending	imf lang::en chapter::090 module::090-03 review::pending
IMF-090-03-0012-en	Why does mycophenolate disproportionately affect lymphocytes?	It inhibits inosine-monophosphate dehydrogenase, limiting guanine synthesis, and lymphocytes rely heavily on the de novo pathway.	Integrated Medical Foundations; chapter 90, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 0694dc90df0ccef97f481656b1de8e0cd5702df8e85ec52e98ba00ec91b97b40; editorial review pending	imf lang::en chapter::090 module::090-03 review::pending
IMF-090-03-0013-en	Why can dihydropyrimidine dehydrogenase deficiency cause catastrophic fluoropyrimidine toxicity?	The same enzyme that initiates uracil and thymine breakdown also clears fluoropyrimidine drugs.	Integrated Medical Foundations; chapter 90, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 0694dc90df0ccef97f481656b1de8e0cd5702df8e85ec52e98ba00ec91b97b40; editorial review pending	imf lang::en chapter::090 module::090-03 review::pending
IMF-090-03-0014-en	How does tumour lysis syndrome injure the kidney, and when is uricase favoured?	Mass cell destruction releases nucleic acids whose purines become urate, causing kidney injury; uricase is favoured when rapid urate removal is needed.	Integrated Medical Foundations; chapter 90, TTS module 3; https://theisegoria.github.io/medical-textbook/integrated-medical-foundations-expanded-english.md; module SHA256 at export: 0694dc90df0ccef97f481656b1de8e0cd5702df8e85ec52e98ba00ec91b97b40; editorial review pending	imf lang::en chapter::090 module::090-03 review::pending