A fatal case associated with severe hyperammonaemia is described in which no urea cycle enzyme deficiency could be found. This prompted further investigation of blood ammonia levels in neonates admitted to the premature baby unit at Hammersmith Hospital. 102 specimens were taken from 42 babies within the first 3 weeks of life; the babies had a variety of clinical conditions. The mean ammonia le...

There is consensus that excess of gut-derived ammonia which is not cleared from the blood plays an important role in the pathogenesis of HE. However, as discussed elsewhere in this book, a growing body of evidence suggests signi fi cant contribution of other factors, such as proin fl ammatory cytokines and hyponatremia. Moreover, there is a long list of gut-derived toxins that accumulate in the...

OBJECTIVE The combination of persistent hyperammonemia and hypoketotic hypoglycemia in infancy presents a diagnostic challenge. Investigation of the possible causes and regulators of the ammonia and glucose disposal may result in a true diagnosis and predict an optimum treatment. PATIENT Since the neonatal period, a white girl had been treated for hyperammonemia and postprandial hypoglycemia ...

A microassay for blood ammonia has been developed. After dilution, blood is dialyzed by a continuous flow procedure, and the ammonium ions in the dialysate are assayed colorimetrically by the hypochlorite-phenol Berthelot reaction. Concentrations from 1 to 400 mumol/l NH+4 can be measured in a 50 mul whole blood sample. Using slight modifications, concentrations up to 800 mumol/l NH+4 can be de...

1. The effects of intestinal ammonia in uraemia have been studied by administering a urease inhibitor, acetohydroxamic acid, to bilaterally nephrectomized rats. 2. Ammonia concentration was significantly decreased in the colon although it remained slightly higher than in normal animals. Caecal ammonia concentration was not altered. Total ammonia content was decreased in both colon and caecum. 3...

The recent widespread interest in blood ammonia determinations in normal and abnormal clinical states (McDermott and Adams, 1954; Schwartz, Phillips, Gabuzda, and Davidson, 1953; White, Phear, Summerskill, and Sherlock, 1955), together with discrepant reports from various laboratories, have prompted a critical examination of the Conway microdiffusion technique in blood analysis. Method The meth...

The prevalence and magnitude of valproic acid (VPA)-related hyperammonemia (HA) were estimated by a review of the literature, and the clinical symptomatology and risk factors for the development of HA determined by researchers at university hospitals in Santiago, Chile; and Rush University Medical Center, Chicago, IL. Out of 183 studies between 1980 and 2005, 24 met inclusion criteria; 7 were p...

1. The effects of acute acid-base alterations on renal ammonia production and glutamine metabolism were studied in anaesthetized dogs. 2. Plasma glutamine rose with acidosis and also when both PCO2 and plasma HCO-3 were raised isohydrically. 3. Blood urea fell when acidosis was induced with hydrochloric acid. 4. The renal production of ammonia per ml of renal blood flow was increased in acidosi...

THE oxyhaemoglobin content of blood can be rapidly and accurately estimated with the help of a photoelectric colorimeter. In the absence of oxyhaemoglobin or of other pigments, methaemoglobin can be determined in the same way. In whole blood the presence of metor of sulph-haemoglobin or of other pigments can be detected. The experiments also indicate that the use of 084% ammonia as a diluent fo...

The net renal metabolism of amino acids and ammonia in the post absorptive state was evaluated in subjects with normal renal function and in patients with chronic renal insufficiency by measuring renal uptake and release, and urinary excretion of free amino acids and ammonia. In normal subjects the kidney extracts glutamine, proline, citrulline, and phenylalanine and releases serine, arginine, ...