Hyperammonemia is considered the main responsible for the neurological alterations found in liver disease and hepatic encephalopathy, including decreased intelectual and cognitive function. Ammonia affects both excitatory and inhibitory synaptic transmission in the mammalian brain by a variety of mechanisms. LTP is impaired in hyperammonemia and this may contribute to the impairment of cognitiv...

PURPOSE Valproic acid (VPA), which is widely used to treat epilepsy, migraine, and bipolar disorder, can causes severe hyperammonemia. However, the mechanism responsible for this adverse effect is not readily apparent. We previously reported that phenytoin coadministration is a strong risk factor for the development of hyperammonemia during VPA-based therapy. In this study, we focused on glutam...

The effect of hyperammonemia of varying degree and duration on the gamma-glutamyl-transpeptidase (GGT) activity was studied in the homogenates and capillaries of different brain regions of the rat. "Acute" hyperammonemia (750 and 600 mg of ammonium acetate per kg b.w. were injected i.p. at 30 min interval, and the animals were decapitated immediately), in which blood ammonia was increased 14-fo...

The Abernethy malformation is a rare congenital malformation defined by the presence of an extrahepatic portosystemic shunt. Although most patients are asymptomatic, clinical encephalopathy is present in 15% of cases. We present a patient with type 2 Abernethy malformation, hyperammonemia, and encephalopathy. Shunt closure was performed successfully using interventional angiography; however, hy...

Valproic acid is used in the treatment of multiple disorders. Adverse effects from valproic acid include hepatotoxicity, hypotension, metabolic acidosis, and decreased mental status. Valproic acid also causes hyperammonemia. Many physicians assume that this is due to a supratherapeutic valproic acid concentration; when in fact, it can occur with therapeutic valproic acid concentrations. This is...

Hyperammonemia is an acute or chronic intoxication with ammonia and ammonium associated elevated levels in serum due to either its increased production and/or decreased detoxification. can result from a variety of causes clinically presents unspecific signs symptoms, including asthenia, encephalopathy, liver steatosis fibrosis, sarcopenia. With impaired function, hyperammonemia most frequently ...

Life-threatening hyperammonemia is uncommon in patients with mitochondrial disorders (MDs).When present, it is usualy due to TMEM70 deficiency [1] and only rarely is it noted in other MDs [2]. Hyperammonemia was documented in patients with Barth syndrome [2], maternally inherited Leigh syndrome (MILS) [3], pyruvate dehydrogenase deficiency [4], pyruvate carboxylase deficiency [5], complex III d...

Two cases of hyperammonemia with elevated citrulline are reported, one resulting from a deficiency of pyruvate carboxylase and the other from a partial deficiency of argininosuccinate synthetase. Diagnosis was based on clinical, biochemical and amino acid profiles. The utility of amino acid determinations in hyperammonemia suspected to underlie an inborn error of metabolism is emphasized.

Hyperammonemia and sarcopenia (loss of skeletal muscle) are consistent abnormalities in cirrhosis and portosystemic shunting. We have shown that muscle ubiquitin-proteasome components are not increased with hyperammonemia despite sarcopenia. This suggests that an alternative mechanism of proteolysis contributes to sarcopenia in cirrhosis. We hypothesized that autophagy could be this alternative...

Hyperammonemia is a true neonatal emergency with high toxicity for the central nervous system and developmental delay. The causes of neonatal hyperammonemia are genetic defects of urea cycle enzymes, organic acidemias, lysinuric protein intolerance, hyperammonemia-hyperornithinemia- homocitrullinemia syndrome, transient hyperammonemia of the newborn, and congenital hyperinsulinism with hyperamm...