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Ammonia metabolism in a family affected by hyperargininemia.
Diabete Metab. 1981 Mar; 7(1):5-11.DM

Abstract

A French-Canadian family, with a 14-year old mentally retarded girl, was investigated for hyperargininemia. The girl showed a fasting plasma ammonia N concentration of 100 micrograms/dl (normal : 50.5 +/- 13 micrograms/dl), and a two-hour post protein load level of 183 micrograms/dl (normal : 51.6 +/- 17.6 micrograms/dl). Plasma urea N was lower than normal in the post-load sample. Arginine concentrations were 11 times normal in the plasma, 47 times normal in the urine and 4 times normal in erythrocytes. Measurement of erythrocyte arginase showed only 1% activity in the propositus, and 52-54% in the parents and a sibling as compared to controls. In heterozygous members of the family, the Km (arginine) was similar to controls. Column chromatography of serum amino acids in the propositus showed arginine to be 17.6 S.D. higher than the normal mean. A characteristic cystine-lysinuria pattern of urinary amino acids was also seen. Measurement of other urinary nitrogenous metabolites showed low urinary urea and excessive orotic aciduria. On "normal" food intake, the patient excreted 122 mg of orotic acid/24 h, as against 3.7 mg by the sibling and 3.9 mg by the mother. It is postulated that the level of ornithine in hepatocyte mitochondria is critical to the disposal of carbamyl phosphate. The lack of normal regeneration of ornithine by liver arginase, and an excessive urinary excretion may be responsible for its low mitochondrial concentration. This would cause diversion of unmetabolised carbamyl phosphate towards orotic acid synthesis or ammonia production.

Authors

No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Case Reports
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

7238975

Citation

Qureshi, I A., et al. "Ammonia Metabolism in a Family Affected By Hyperargininemia." Diabete & Metabolisme, vol. 7, no. 1, 1981, pp. 5-11.
Qureshi IA, Letarte J, Ouellet R, et al. Ammonia metabolism in a family affected by hyperargininemia. Diabete Metab. 1981;7(1):5-11.
Qureshi, I. A., Letarte, J., Ouellet, R., Lelièvre, M., & Laberge, C. (1981). Ammonia metabolism in a family affected by hyperargininemia. Diabete & Metabolisme, 7(1), 5-11.
Qureshi IA, et al. Ammonia Metabolism in a Family Affected By Hyperargininemia. Diabete Metab. 1981;7(1):5-11. PubMed PMID: 7238975.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Ammonia metabolism in a family affected by hyperargininemia. AU - Qureshi,I A, AU - Letarte,J, AU - Ouellet,R, AU - Lelièvre,M, AU - Laberge,C, PY - 1981/3/1/pubmed PY - 2000/3/11/medline PY - 1981/3/1/entrez SP - 5 EP - 11 JF - Diabete & metabolisme JO - Diabete Metab VL - 7 IS - 1 N2 - A French-Canadian family, with a 14-year old mentally retarded girl, was investigated for hyperargininemia. The girl showed a fasting plasma ammonia N concentration of 100 micrograms/dl (normal : 50.5 +/- 13 micrograms/dl), and a two-hour post protein load level of 183 micrograms/dl (normal : 51.6 +/- 17.6 micrograms/dl). Plasma urea N was lower than normal in the post-load sample. Arginine concentrations were 11 times normal in the plasma, 47 times normal in the urine and 4 times normal in erythrocytes. Measurement of erythrocyte arginase showed only 1% activity in the propositus, and 52-54% in the parents and a sibling as compared to controls. In heterozygous members of the family, the Km (arginine) was similar to controls. Column chromatography of serum amino acids in the propositus showed arginine to be 17.6 S.D. higher than the normal mean. A characteristic cystine-lysinuria pattern of urinary amino acids was also seen. Measurement of other urinary nitrogenous metabolites showed low urinary urea and excessive orotic aciduria. On "normal" food intake, the patient excreted 122 mg of orotic acid/24 h, as against 3.7 mg by the sibling and 3.9 mg by the mother. It is postulated that the level of ornithine in hepatocyte mitochondria is critical to the disposal of carbamyl phosphate. The lack of normal regeneration of ornithine by liver arginase, and an excessive urinary excretion may be responsible for its low mitochondrial concentration. This would cause diversion of unmetabolised carbamyl phosphate towards orotic acid synthesis or ammonia production. SN - 0338-1684 UR - https://www.unboundmedicine.com/medline/citation/7238975/Ammonia_metabolism_in_a_family_affected_by_hyperargininemia_ L2 - https://medlineplus.gov/aminoacidmetabolismdisorders.html DB - PRIME DP - Unbound Medicine ER -