Posts Categorized: Part 08: AMINO ACIDS

Adipose transplant for MSUD

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In an article from a couple of years ago, Zimmerman et al (Mol Genet Metab. 2013 Aug;109(4):345-53) discuss evidence for improvement of biochemical measures with adipose transplant in 2 mouse models of maple syrup urine disease (MSUD). This brings up the very interesting question about which soft tissues provide adequate enzymatic activity for therapeutic replacement potential. […]

Engineering the gut microbiota to treat hyperammonemia

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Gut microbiota can be altered to ameliorate or prevent disease states. In the intestine, bacterial urease converts host-derived urea to ammonia and carbon dioxide, contributing to hyperammonemia-associated neurotoxicity and encephalopathy in patients with liver disease. In their JCI paper, Shen and colleagues engineered murine gut microbiota to reduce urease activity. Animals were depleted of their preexisting […]

Is BRIEF sufficient to monitor executive function in PKU?

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Liemburg et al. (2015) explored if the Behavior Rating Inventory of Executive Function (BRIEF) instrument is sufficient to monitor for Executive Function (EF) deficits in patients with PKU. 55 adult PKU patients (mean age 28.3 ± 6.2 years) filled out the BRIEF-A questionnaire and performed computerized tasks measuring executive functions (inhibition, cognitive flexibility, and working […]

Towards chaperone therapy in pyridoxine-resistant classical homocystinuria

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Melenovská P, Kopecká J, Krijt J, Hnízda A, Raková K, Janošík M, Wilcken B, Kožich V.  Chaperone therapy for homocystinuria: the rescue of CBS mutations by heme arginate. J Inherit Metab Dis. 2014 Oct 21. [Epub ahead of print]   Mutations in the CBS gene cause classical homocystinuria (cystathionine beta-synthase deficiency). For patients who do not […]

Tyrosinemia & NTBC: 168 patients

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Mayorandan et al. performed a cross-sectional study on Hepatorenal tyrosinaemia. Questionnaires were used to collect retrospective data about 168 patients with Tyr 1 from 21 centres (Europe, Turkey and Israel). The results of this study highlight the importance of NTBC accompanied by natural protein restriction (supplemented with essential amino acids) in the prevention of complications […]

MSUD and BCKD expression

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During a recent literature review on maple syrup urine disease, I came across an older article from 1998 (Suryawan et al. Am J Clin Nutr. 1998;68:72–81.) in which the authors examined branch chain amino acid metabolism (BCAT and BCKD) in various tissues. They found that most of the oxidative capacity was in skeletal muscle and liver (with muscle  representing the […]

SAM and SAH measurements in renal transplantation

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Klepacki et al. (Clin Chim Acta. 2013 Jun 5;421:91-7. doi: 10.1016/j.cca.2013.03.003) developed reliable methodology to measure adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) levels via LC-MS/MS. The found SAH concentrations to be elevated in kidney transplant patients associated with acute rejection and nephrotoxicity events  compared to healthy controls and transplant patients without  transplant dysfunction. This brings up interesting questions about the role of metabolism […]

Sapropterin dihydrochloride in maternal phenylketonuria

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Feillet F et al. Use of sapropterin dihydrochloride in maternal phenylketonuria. A European experience of eight cases. J Inherit Metab Dis. 2014 May 1. [Epub ahead of print] Feillet et al describe the use of sapropterin dihydrochloride during pregnancy in eight cases of maternal phenylketonuria. Seven of eight patients (who were known to be responsive […]

Neu-Laxova syndrome is an inborn error of serine biosynthesis

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Neu-Laxova syndrome (NLS) is a rare autosomal-recessive disorder characterized by severe fetal growth restriction, microcephaly, a distinct facial appearance, ichthyosis, skeletal anomalies, and perinatal lethality. Through a positional-mapping study combining autozygosity mapping and whole-exome sequencing, Shaheen and colleagues surprisingly found that NLS is caused by mutations in PHGDH encoding for 3-phosphoglycerate dehydrogenase is the first enzyme in the […]

Hyperammonemia pathophysiology

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The mechanisms leading to the toxicity of hyperammonemia have been long known to be complex. For a review of what was known in 2012, see this article: Auron A, Brophy PD. Pediatr Nephrol. 2012 Feb;27(2):207-22. doi: 10.1007/s00467-011-1838-5. Epub 2011 Mar 23. Hyperammonemia in review: pathophysiology, diagnosis, and treatment. In this review, they discuss amino acid […]