Reye's syndrome. I. Blood ammonia and consideration of the nonhistologic diagnosis

Fatal hyperammonemia after orthotopic lung transplantation

BACKGROUND

A case of fatal hyperammonemia complicating orthotopic lung transplantation was previously reported.

OBJECTIVE

To describe the incidence, clinical features, and treatment of hyperammonemia associated with orthotopic lung transplantation.

DESIGN

Retrospective cohort analysis.

SETTING

Academic medical center and lung transplantation center in Philadelphia, Pennsylvania.

PATIENTS

145 sequential adult patients who underwent orthotopic lung transplantation.

MEASUREMENTS

Plasma ammonium levels.

RESULTS

Six of the 145 patients who had had orthotopic lung transplantation developed hyperammonemia, all within the first 26 days after transplantation. The 30-day post-transplantation mortality rate was 67% for patients with hyperammonemia compared with 17% for those without hyperammonemia (P = 0.01). Development of major gastrointestinal complications (P = 0.03), use of total parenteral nutrition (P < 0.001), and lung transplantation for primary pulmonary hypertension (P = 0.045) were associated with hyperammonemia.

CONCLUSIONS

Hyperammonemia is a potentially fatal event occurring after orthotopic lung transplantation. It is associated with high nitrogen load, concurrent medical stressors, primary pulmonary hypertension, and hepatic glutamine synthetase deficiency.

Prevention of 4-pentenoic acid-induced liver injury in rats by 16,16-dimethyl PGE2

16,16-Dimethyl PGE2 (dmPGE2) is known to protect against cellular damage in various tissues. Histological and biochemical approaches were used to examine the effect of this prostaglandin on hepatocellular damage in an experimental Reye's syndrome model produced in rats by 4-pentenoic acid. Chronic intraperitoneal administration of 4-pentenoic acid induced an accumulation of fatty droplets throughout the hepatic lobules along with mitochondrial abnormalities including swelling, disappearance of christae, and heterogeneity of matrix. These abnormalities were more intense in the marginal zone and successively decreased nearer to the central vein. Such hepatic abnormalities were markedly reduced by the combined administration of dmPGE2 with 4-pentenoic acid. Biochemical examination confirmed that dmPGE2 was able to inhibit the accumulation of hepatic triglyceride seen after the treatment with 4-pentenoic acid alone. These results indicated that dmPGE2 can prevent characteristic hepatocellular damage in this experimental Reye's syndrome model, suggesting that the involvement of prostaglandins should be taken into account in discussing the etiology and management of this syndrome.

Biochemical relationships between Reye's and Reye's-like metabolic and toxicological syndromes

Reye's syndrome is a hepatic encephalopathy with fatty infiltration of the liver and is due to mitochondrial dysfunction. Knowledge of the mechanisms causing Reye's syndrome has been gained from the study of Reye's syndrome-like diseases, including inborn errors of mitochondrial energy production, viral disease and toxicological injury. Entry of fatty acids into mitochondria or beta-oxidation itself may be impaired. Toxins such as hypoglycin, pentanoate, valproate, salicylate, and their metabolites inhibit beta-oxidation pathways and can produce Reye's syndrome-like presentations. Biochemical manifestations of the diverse causes of Reye's syndrome-like disorders are similar and include: hypoglycaemia due to impaired gluconeogenesis, accumulation of fatty acids, fatty acyl CoAs, and acyl carnitines with depletion of free CoA and carnitine. Accumulated products may further injure mitochondria and exacerbate impaired beta-oxidation, uncouple oxidative phosphorylation or increase mitochondrial permeability. Mitochondrial swelling and steatosis of hepatic cells are the histological result. With the advances of biochemical techniques for the study of organic acid excretion patterns, serum fatty acid patterns and identification of enzymatic deficiencies in cells from patients with Reye's syndrome-like presentations, it is clear that Reye's syndrome is, in part, a collection of various inborn errors and toxicological states. Circumstances such as viral disease, prolonged fasting and drugs may precipitate clinical expression of these deficiencies as Reye's syndrome. As work progresses, further causes of Reye's syndrome will be identified.

Advances in the application of biochemical tests to diseases of the liver and biliary tract: their role in diagnosis, prognosis, and the elucidation of pathogenetic mechanisms

Despite the biochemical complexity of the liver, few laboratory tests provide discriminatory diagnostic information in patients with hepatobiliary disease. Recent efforts have concentrated upon tests which assess the function of the liver, the severity of the disease state, and underlying pathological processes. Bile Acids: The emergence of facile technology and widespread application has brought the realization that these assays are not as sensitive in detecting liver disease as previously believed, although the cholate/chenate ratio may be useful in distinguishing cholestasis from chronic liver disease. The presence of unusual bile acids in serum or urine may be helpful in some cases. Drug Metabolism: A number of tests provide good evidence about liver function, hepatic blood flow and portal shunting, but the aminopyrine breath tests is the most useful, giving prognostic information in acetaminophen overdose and alcoholic liver disease. The antipyrine half-life identifies surgical cases at risk from poor hepatic function. Proteins and Immunochemical Tests: Interest has developed in plasma proteins such as prealbumin and retinol-binding protein to monitor hepatic protein synthetic function. Secretory IgA is more elevated in biliary tract disease, unlike the native protein which is increased principally in cirrhosis. Type III procollagen can be measured in serum, and correlates with the activity of collagen synthesis and the degree of fibrosis in biopsy samples. Reye's Syndrome: Biochemical tests play an essential role in diagnosis of this recently discovered disease. These will be presented and discussed.

Interactions of aspirin and other potential etiologic factors in an animal model of Reye syndrome

Recent studies of Reye syndrome (RS) patients have suggested aspirin treatment as a possible factor in the etiology of this often fatal childhood disorder. the relationship of aspirin treatment to other factors that have been strongly implicated (influenza, ammonia toxicity) cannot be examined directly in patients because aspirin treatment is usually initiated by family members in the prodromal period before RS is diagnosed. In this report we describe the use of an animal model for RS in examining the interactions of these several potential etiological factors. Hyperammonemia and coma were produced in young male ferrets by a brief feeding of an arginine-deficient diet. The effects of influenza infection or aspirin treatment (or both) of control and hyperammonemic ferrets on their serum levels of ammonia, glutamic-oxaloacetic transaminase (GOT;L-aspartate:2-oxoglutarate aminotransferase, EC 2.6.1.1), ornithine carbamoyltransferase (OCT; carbamoylphosphate:L-ornithine carbamoyltransferase, EC 2.1.3.3), bilirubin, and salicylate were studied. Liver levels of lipids, proteins, and several urea-cycle enzymes were also determined in the comatose ferrets and compared with those of untreated controls and of controls treated with influenza or aspirin, or both. Synergism of these three factors (hyperammonemia, influenza infection, and aspirin treatment) in causing RS-like alterations in these parameters was observed.

Reye's syndrome in children under three years old

The National Childhood Encephalopathy Study identified 37 cases of Reye's syndrome in children aged between 2 and 36 months in a 3-year period, giving an estimated incidence in Great Britain of 0.7/100 000 children a year. The diagnostic features were neither consistently positive in these cases, nor negative in 11 others later considered not to have Reye's syndrome. The prognosis was poor; the fatality rate was 46%, and 60% of the survivors were handicapped. A surveillance scheme to investigate pathological, clinical, and epidemiological factors in this rare condition is required. This has now been set up in the UK.

Reye syndrome: a predictably curable disease

Seventeen years after the initial description of this syndrome of hepatic failure and encephalopathy, the etiology and pathophysiology are still not well defined. Clinical staging of the disease proposed by Lovejoy and colleagues is helpful and is recommended as a standard to be followed by referring physicians and hospital-based pediatricians and intensivists. A new classification based on the status of intracranial pressure and unrelated to clinical, laboratory, or EEG staging is presented.

Reye syndrome associated with Hemophilus influenzae infection

A case of Reye syndrome in an infant associated with culture-proven Hemophilus influenzae type d infection and probable meningitis is presented. This represents the second such reported case and the first to be described in detail. The criteria for the clinical and chemical diagnosis of Reye syndrome are reviewed. Pertinent and abnormal features of this patient's presentation are discussed. The finding of a non-visualizing liver on technetium-99m sulfur colloid isotope scan and possible mechanisms are discussed.

Extrapulmonary manifestations of adenovirus type 7 pneumonia simulating Reye syndrome and the possible role of an adenovirus toxin

Three children developed extensive extrapulmonary disease in the course of fatal adenovirus type 7 pneumonia. Several clinical features, including the unexpected onset of coma, suggested the development of Reye syndrome, but biochemical and histopathologic findings were inconsistent with this diagnosis. Virologic and pathologic studies did not reveal evidence of extrapulmonary adenovirus infection, despite clinical involvement of the liver, skeletal muscle, and central nervous system. The detection in premortem sera from all three patients of adenovirus penton antigen, known to be cytotoxic in vitro, suggests a possible mechanism for the production of extrapulmonary pathology in the absence of extrapulmonary virus infection.

Encephalopathy and fatty metamorphosis of the liver associated with cold-agglutinin autoimmune hemolytic anemia

Three patients with encephalopathy clinically indistinguishable from Reye syndrome but associated with elevated cold-agglutinin titers and antiglobulin-I autoimmune hemolytic anemia are reported. The patients were treated with exchange transfusions, dexamethasone, controlled hyperventilation, and intracranial pressure monitoring. Liver biopsy specimens in two of the three patients showed fatty infiltration of the hepatocytes, but the light microscopic and electron microscopic appearance of the liver was not typical for Reye syndrome. These patients are reported to alert physicians to a metabolic encephalopathy in children which mimics Reye syndrome, but is distinctly different in clinical course and complicated by cold agglutinins and an autoimmune hemolytic anemia.

Treatment of elevated intracranial pressure in Reye syndrome

Continuous intraventricular monitoring of intracranial pressure appears to be a useful aid in the management of patients with Reye syndrome, especially those in stage 3 or 4 coma, in which the mortality rate remains high. Elevations in intracranial pressure can be treated promptly and before the patient shows clinical signs of deterioration. Careful attention to adequate airway care is essential. The use of paralytic agents to reduce pressure secondary to muscle movement is useful. The minimum dose of mannitol required can be carefully titrated, and sudden pressure changes can be combated by release of small amounts of cerebrospinal fluid.

Severe coagulation abnormalities in Reye syndrome

Coagulation studies were performed on 13 children with clinical diagnoses of Reye syndrome. Four had abnormalities so severe that transfusion of coagulation factors and platelets were required prior to percutaneous liver biopsy. In one of these, abnormalities frequently found in association with acute hepatic failure were present. Disseminated intravascular coagulation was noted in two, while in the fourth child laboratory data were most consistent with that process. Although the coagulation defect associated with Reye syndrome is most often due to decreased production of all coagulation factors except VIII, these patients demonstrate that consumption can also occur. The severity of the coagulopathies found indicates that bleeding can become a major complication in the diagnosis and management of Reye syndrome.

Effect of pent-4-enoic acid, propionic acid and other short-chain fatty acids on citrulline synthesis in rat liver mitochondria

19 The effect of pent-4-enoic acid, propionic acid and several other short-chain fatty acids on citrulline synthesis in rat liver mitochondria was studied. 2.Pent-4-enoate at 1 mM inhibited mitochondrial citulline synthesis by about 80-90%. It is concluded that pent-4-enoate inhibits citrulline synthesis by interfering with some aspect of mitochondrial energy metabolism. This results in impairment of mitochondrial ornithine uptake or depletion of mitochondrial ATP, which, in turn, impairs carbamoyl phosphate synthesis or both. Evidence in support of this conclusion includes: pent-4-enoate has no effect on citrulline synthesis supported by succinate or exogenous ATP; pent-4-enoate lowers the medium plus mitochondrial ATP concentration; finally, when glutamate is the oxidizable substrate, pent-4-enoate decreases the carbamoyl phosphate concentration in mitochondria incubated without ornithine to minimize citrulline synthesis and impairs the mitochondrial uptake of ornithine, but it has neither effect when succinate is the oxidizable substrate. 4. Propionate, butyrate and crotonate also inhibit mitochondrial citrulline synthesis, but much less than pent-4-enoate. 5. Acetate, pentanoate, pent-2-enoate, hexanoate, octanoate, isovalerate, tiglylate and alpha-methylbutyrate have little or no effect on mitochondrial citrulline synthesis.

Acute liver disease and encephalopathy mimicking Reye syndrome. A report of three cases

Three patients are described whose clinical presentation suggested Reye syndrome, and in whom the initial laboratory investigations supported the diagnosis. The subsequent clinical and biochemical evolution of the illness differed from that of Reye syndrome. The liver biopsy of each patient revealed changes in centrilobular hepatocytes rather than the diffuse small droplet fatty change characteristic of Reye syndrome. In each of them normal liver functions were regained. The findings in these patients suggest that a firm diagnosis of Reye syndrome cannot be made without histologic examination of the liver.

Reye syndrome: treatment by exchange transfusion with special reference to the 1974 epidemic in Cincinnati, Ohio

The treatment of 66 children with Reye syndrome proved by hepatic biopsy or autopsy is described. Prior to the utilization of exchange transfusion early in the course of the disease, our case fatality rate was 100% of nine patients. With early diagnosis and early exchange transfusion, the case fatality rate was reduced to 27% of 44 patients. During the 1974 epidemic of Reye syndrome, 26 children were treated. In 18 children the diagnosis was established by hepatic biopsy; 16 received one or more exchange transfusions. There were no deaths among these 26 patients. In the 1974 epidemic, the national case fatality rate was estimated to be 40%. Exchange transfusion appears to have been an important factor in the reduction of the case fatality rate among our patients.