Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “hyperammonemia”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 397 records · Page 22Linked to original sources
PubMed2004

Inborn errors of metabolism: an update on epidemiology and on neonatal-onset hyperammonemia.

Inborn errors of metabolism (IEM) are a highly heterogeneous group of genetic conditions and represent a relevant cause of morbidity and mortality in the pediatric population. IEM, which are individually rare but collectively numerous, are well-recognized entities of the generic class of "rare" diseases. Since the first descriptions by Garrod at the beginning of the 20th century, several hundred new disorders have been defined, as new biochemical and molecular diagnostic tools became available. The clinical pictures of single diseases are extremely diverse, ranging from acute life-threatening manifestations to chronic late-onset forms, with single or multiorgan involvement. Mental retardation and progressive neurological impairment often characterize the clinical course. One of the principles to prevent high morbidity and mortality rates is early recognition followed by prompt therapeutic intervention. Therefore, a small number of treatable IEM is subject to neonatal mass screening. More recently, an innovative technique, based on tandem mass spectrometry, has expanded the range of neonatal screening to several additional disorders. Owing to the extreme heterogeneity, as well as to the increasing number of new disorders, exhaustive and updated epidemiological data on the overall occurrence of IEM are lacking. A national retrospective study was conducted to define the epidemiological profile of IEM in Italy and to estimate the costs related to the disease burden. Other relevant issues of our investigations focused on creating protocols of treatment for neonatal IEM, and on the development of new methods for the biochemical diagnosis.

Humans↗
PubMed1964

PSYCHOLOGICAL CHANGES ASSOCIATED WITH INDUCED HYPERAMMONEMIA.

Normal volunteers infused with ammonium acetate for 3 hours developed a characteristic behavior pattern resembling that of prehepatic coma. They demonstrated certain specific defects in motor performance and recognition aswell as significant lowering of critical flicker fusion. These findings arecorrelated with the concentration of ammonia in arterial blood.

Ammonium Compounds↗
PubMed2000

Ornithine aminotransferase, a potential target for the treatment of hyperammonemias.

Ornithine-delta-aminotransferase (OAT) (EC 2.6.1.13) is a pyridoxal-5' phosphate dependent mitochondrial matrix enzyme. It controls the L-ornithine (Orn) level in tissues by catalysing the transfer of the delta-amino group of Orn to 2-oxoglutarate. The products of this reaction are L-glutamate-gamma-semialdehyde and L-glutamate. Among the compounds known to inhibit (or inactivate) OAT, only L-canaline and (SS)-5-(fluoromethyl)ornithine [(SS)-5FMOrn] are selective for OAT. Treatment of laboratory animals with 5FMOrn causes a dramatic accumulation of Orn in most tissues and organs, and the enhanced formation of urea due to saturation of ornithine:carbamoyltransferase with its substrate. The enhancement of urea formation by increased endogenous levels of Orn is comparable with that produced by large doses of Orn and arginine, a treatment known to enhance the detoxification of ammonia. However, protection to lethal doses of ammonium salts by exogenous Orn is rapidly fading. In contrast, inactivation of OAT by a small dose of 5FMOrn renders a long-lasting protective effect against various forms of hyperammonemic states. Among these the reduction of ammonia concentrations in blood and tissues, and the reduction of the pathologic excretion of orotic acid to normal levels in mice with hereditary defects of the urea cycle, were most impressive. In human hereditary OAT deficiency the elevated intraocular concentrations of Orn are considered to be a cause of gyrate atrophy. This is presumably the reason, why OAT has not been considered as a therapeutically useful target. Chronic inactivation of OAT by repeated administration of 5FMOrn, caused elevated intraocular Orn concentrations, but this treatment had no effect on the function and histology of the visual system, or the behaviour of adult mice. The confirmation of this and related observations in higher species will show, whether OAT inactivation has potentials in the treatment of hyperammonemic states.

Ammonia↗
PubMedDate not supplied

Role of Helicobacter pylori infection in hyperammonemia and subclinical hepatic encephalopathy in cirrhosis of liver.

INTRODUCTION: Gastric Helicobacter pylori infection is believed to be associated with a higher risk of hepatic encephalopathy among patients with cirrhosis of liver. However, the role of this infection in causation of subclinical hepatic encephalopathy has not been studied in detail. METHODS: Patients with cirrhosis of liver but no hepatic encephalopathy underwent venous blood ammonia measurement, psychometric tests (number connection tests [NCT] and figure connection tests [FCT]), and gastric biopsies for presence of H. pylori infection. The results of blood ammonia and psychometric tests in the H. pylori-positive and -negative study subjects were compared. RESULTS: Of 58 patients with liver cirrhosis studied, 31 had evidence of gastric H. pylori infection. Venous blood ammonia levels were comparable in patients with (median 29 mmol/L; range 18-47) and without (34 [15-48] mmol/L; p=ns) H. pylori infection. The time taken to complete NCT trail A (median 37 s [range 25-69] versus 36.5 [26-62]), NCT trail B (64 s [48-91] versus 63.5 [42-88]), FCT trail A (59 s [31-115] versus 58 [38-590]) and FCT trail B (76 s [55-187] versus 82 [36-125]) were similar in those with and those without H. pylori infection. For each of the four tests, the proportion of subjects with abnormal test results was similar among H. pylori-positive and -negative subjects. CONCLUSION: Presence of H. pylori infection among patients with cirrhosis of liver but no overt hepatic encephalopathy is not associated with increase in blood ammonia concentration or deterioration in psychomotor function.

Adolescent↗