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PubMed2002

Continuous renal replacement therapy and plasma exchange in newborns and infants.

The objective of our study was to present our experience in the treatment of small children with continuous renal replacement therapy (CRRT) and plasma exchange (PE). From March 1986 to April 2000, 21 critically ill children (14 newborns and 7 infants) with acute renal failure (ARF) and multiple organ failure were treated with CRRT and PE. In the newborn group, there were 8 males and 6 females, age 15.7 +/- 11.7 days, with body weights of 3,348 +/- 585 g. In the infant group, there were 4 males and 3 females, age 118 +/- 67 days, with body weights 5,186 +/- 734 g. The indications for the beginning of CRRT and/or PE were ARF with anuria and hyperhydration (17 patients), azotemia and anuria (1 patient), hemolytic uremic syndrome (1 patient), and hyperammonemia (2 patients). In all patients, peritoneal dialysis was considered inappropriate. PE and CRRT monitors were used, double lumen 5 Fr and 7 Fr hemodialysis catheters were the vascular access, low dose heparin and prostacyclin were anticoagulants, and lactate or bicarbonate buffered replacement solutions were used predilutionally. Side events were clotting within the extracorporeal circuit, catheter malfunction, serious hypotension (6 patients), and pulmonary edema (1 patient). Ten of 21 patients (47.6%) recovered renal function and 9 of 21 patients (42.9%) survived. Survivors had fewer failing organs (3.6 +/- 0.5) than nonsurvivors (4.8 +/- 0.9) (p = 0.0008). Pump driven CRRT and PE were feasible, efficient, and safe procedures in newborns and infants. Without CRRT, it is uncertain whether any of our patients would have the chance to survive.

Acute Kidney Injury↗

PubMed2002

Serum and CSF glutamine levels in valproate-related hyperammonemic encephalopathy.

PURPOSE: To investigate ammonia and glutamine levels in valproate (VPA)-related hyperammonemic encephalopathy (VHE). METHODS: We reviewed the medical records and EEG recordings of seven adults diagnosed with VHE. RESULTS: Venous ammonia levels were elevated in five (71%) of the seven patients. Elevated serum or cerebrospinal fluid (CSF) glutamine levels were found in four (80%) of five cases tested, including two who had normal ammonia levels. Initial behavioral signs included violent outbursts in three patients, paranoid ideation severe enough to require restraint in two cases, and milder abnormalities in two instances. The severity of encephalopathy was not related to any particular serum VPA level. In four patients serum VPA levels did not exceed 100 microg/ml, and in one case, VHE developed after taking only one 250-mg dose. Symptoms eventually cleared after reducing the dose of, or discontinuing, VPA. Liver-function tests were normal. Each of six patients tested had EEG findings that supported the diagnosis of VHE and excluded nonconvulsive status epilepticus. The rate of normalization of one patient's serum glutamine level and the EEGs of two cases correlated better with the timing of their delayed clinical recovery than did the more rapid rate of decline of the serum ammonia levels. CONCLUSIONS: Serum or CSF glutamine levels are initially elevated in a majority of patients with suspected VHE, sometimes in the absence of hyperammonemia. Glutamine levels may be useful adjunctive laboratory tests for the diagnosis of VHE.

Adolescent↗

PubMed2002

Treatment of liver failure in rats with end-stage cirrhosis by transplantation of immortalized hepatocytes.

The shortage of organ donors has impeded the development of human hepatocyte transplantation. Immortalized hepatocytes could provide an unlimited supply of transplantable cells. To determine whether immortalized hepatocytes could provide global metabolic support in end-stage liver disease, 35 immortalized rat hepatocyte clones were developed by transduction with the gene encoding the simian virus 40 T antigen (SV40Tag). The SV40Tag sequence and a suicide gene, herpes simplex virus thymidine kinase (HSV-tk), were flanked by loxP sequences so that they could be excised by Cre/lox recombination. When transplanted into the spleens of portacaval-shunted rats, 3 of the 35 immortalized hepatocyte clones prevented the development of hyperammonemia-induced hepatic encephalopathy. The protection was reversed by treatment with ganciclovir, which kills HSV-tk-expressing cells. Transplantation of alginate-encapsulated, immortalized hepatocytes into the spleens of cirrhotic rats resulted in significant improvement in prothrombin time, serum albumin and bilirubin levels, hepatic encephalopathy score, and duration of survival. The metabolic support provided by the immortalized cells equaled that observed after transplantation of primary rat hepatocytes. In conclusion, immortalized hepatocytes can function as well as primary hepatocytes following transplantation and can be engineered to contain safeguards that could make them clinically useful. Further investigation is warranted regarding the mechanisms of loss of mass or function of the transplanted hepatocytes over time and how the relatively few engrafted hepatocytes can ameliorate liver decompensation in cirrhosis.

Animals↗

PubMed2001

Alternative pathway therapy for urea cycle disorders: twenty years later.

Alternative pathway therapy is currently an accepted treatment approach for inborn errors of the urea cycle. This involves the long-term use of oral sodium phenylbutyrate, arginine supplements, or both, depending on the specific enzyme deficiency, and treatment of acute hyperammonemic crises with intravenous sodium benzoate/sodium phenylacetate plus arginine. A review of 20 years of experience with this approach illustrates the strengths and limitations of this treatment. It has clearly decreased the mortality and morbidity from these disorders, but they remain unacceptably high. The medications are generally well tolerated, but severe accidental overdosage has been reported because of the infrequent use of the medication. There is also a difference in their metabolism between newborns and older children that must be addressed in determining dosage. To avoid these complications it is recommended that drug levels in blood be monitored routinely and that very specific treatment protocols and oversight be followed to avoid overdoses. Finally, it must be acknowledged that alternative pathway therapy has limited effectiveness in preventing hyperammonemia and must be combined with effective dietary management. Therefore in children with neonatal-onset disease or in those with very poor metabolic control, liver transplantation should be considered. There should also be the continued search for innovative therapies that may offer a more permanent and complete correction, such as gene therapy.

Amino Acid Metabolism, Inborn Errors↗

PubMed2006

Intermediate dose 5-fluorouracil-induced encephalopathy.

As an acute neurotoxicity, high dose 5-fluorouracil (5-FU)-induced encephalopathy is well-known, but encephalopathy associated with lower dose is rarely reported. Here, we report a case of a male with anal cancer who was treated with 5-FU 1000 mg/m(2), continuous infusion for 5 days q4 weeks. At the second and the fourth cycles of chemotherapy, sudden confusion, cognitive dysfunction and disorientation occurred during 5-FU infusion. They were accompanied by hyperammonemia in the absence of focal neurological deficits or structural abnormalities. These symptoms completely disappeared and the serum ammonia level returned to normal after discontinuation of 5-FU and conservative care. In order to investigate a possible deficit of dihydropyrimidine dehydrogenase (DPD), we checked its mRNA level before and after treatment using real-time PCR. The patient's pre-treatment level was 80% compared with reference group, and it was elevated up to 187% of initial after 5-FU treatment, implying that that his encephalopathy may be 5-FU catabolite type rather than DPD deficiency. In conclusion, we report that encephalopathy can develop even with the dose of 5-FU lower than ever reported, and it should be considered as a differential diagnosis for proper management.

Aged↗

PubMed2003

Hepatic encephalopathy and Helicobacter pylori: a critical reappraisal.

Hepatic encephalopathy (HE) is a frequent complication of liver cirrhosis, and plasma ammonia plays a pivotal role in its pathogenesis. Ammonia disposal in cirrhotics depend on intricately balanced enzyme and transport systems, involving liver, large and small bowel, muscle, and kidney. Recently, it has been suggested that Helicobacter pylori could contribute to hyperammonemia in cirrhotics, but conflicting data are available in the literature. This is a systematic review of experimental (animals and humans), epidemiological, case-control, and prospective studies, to evaluate the arguments in favor and against the role of H. pylori in HE pathogenesis. Although H. pylori produces ammonia in the stomach, several studies have shown that both basal ammonia levels and HE prevalence did not significantly differ between cirrhotics with and without infection. Moreover, some prospective studies have documented that both blood ammonia levels and mental status in HE cirrhotics are not significantly affected by H. pylori eradication. Even if a small sub-group of cirrhotics with both a high bacterial density and more severe hepatic impairment seems to benefit by bacterial eradication, data indicate that ammonia production in the stomach by H. pylori urease appears to be inadequate to clinically affect ammonia disposal in the majority of cirrhotic patients. Further studies are warranted in this field.

Ammonia↗

PubMed2005

Acute valproate poisoning: pharmacokinetics, alteration in fatty acid metabolism, and changes during therapy.

The clinical features, complications, and pharmacokinetics of intentional acute valproic acid (VPA) overdoses are described. Alteration in fatty acid metabolism is evaluated and therapy-induced changes are discussed. Central nervous system features were the predominant clinical manifestations (6/6), followed by respiratory failure (5/6) and multiorgan failure (2/6). Mechanical ventilation was required in 5 of 6 patients because of respiratory depression or deep coma. Hemodialysis was applied in 4/6 of the cases due to hyperammonemia, worsening neurologic condition, or organ dysfunction. Cerebral edema and hemorrhagic pancreatitis ensued in 2/6 of the patients and ICU mortality was 2/6. VPA peak levels ranged from 520 to 1700 mg/L with a mean of 1127 mg/L. Ammonia was elevated in all cases with a mean of 550 microg/dL. All patients showed signs of impaired mitochondrial beta-oxidation with increase of medium- and long-chain acylcarnitines in serum. Severe VPA overdose is associated with a high mortality rate requiring early medical interventions. Beside supportive intensive care, hemodialysis can be considered as an adjunctive measure.

Anticonvulsants↗

PubMed2004

Portosplenic blood flow separation in a patient with portosystemic encephalopathy and a spontaneous splenorenal shunt.

A patient with portosystemic encephalopathy, hyperammonemia, and a spontaneous splenorenal shunt was admitted to the authors' institution after a failed attempt at transvenous retrograde shunt obliteration. As an alternative approach, the authors separated splenic and portal flows by embolizing only the proximal splenic vein while leaving the shunt intact. Thus, the splenic flow could escape into the systemic circulation and an extreme increase in portal pressure was avoided. The procedure could provide rapid decreases in blood ammonia levels and a fast resolution of symptoms, but repeated interventions were required.

Embolization, Therapeutic↗

PubMed2006

Pongamia pinnata modulates the oxidant-antioxidant imbalance in ammonium chloride-induced hyperammonemic rats.

The effect of Pongamia pinnata (an indigenous plant used in Ayurvedic Medicine in India) leaf extract (PPEt) on circulatory lipid peroxidation and antioxidant status was evaluated in ammonium chloride-induced hyperammonemic rats. Enhanced lipid peroxidation in the circulation of ammonium chloride-treated rats was accompanied by a significant decrease in the levels of vitamin A, vitamin C, vitamin E, reduced glutathione (GSH), glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT). PPEt-administered rats experienced a significant reduction in lipid peroxidation with a simultaneous elevation in antioxidant levels. Our results indicate that PPEt modulates these changes by reversing the oxidant-antioxidant imbalance during ammonium chloride-induced hyperammonemia and this could be due to its (i) antihyperammonemic effect by means of detoxifying excess ammonia, urea and creatinine and (ii) antioxidant property. The exact mechanism has to be still investigated and isolation of active constituents is required.

Ammonium Chloride↗

PubMed2006

Interorgan ammonia, glutamate, and glutamine trafficking in pigs with acute liver failure.

Ammonia reduction is the target for therapy of hepatic encephalopathy, but lack of quantitative data about how the individual organs handle ammonia limits our ability to develop novel therapeutic strategies. The study aims were to evaluate interorgan ammonia metabolism quantitatively in a devascularized pig model of acute liver failure (ALF). Ammonia and amino acid fluxes were measured across the portal drained viscera (PDV), kidneys, hind leg, and lungs in ALF pigs. ALF pigs developed hyperammonemia and increased glutamine levels, whereas glutamate levels were decreased. PDV contributed to the hyperammonemic state mainly through increased shunting and not as a result of increased glutamine breakdown. The kidneys were quantitatively as important as PDV in systemic ammonia release, whereas muscle took up ammonia. Data suggest that the lungs are able to remove ammonia from the circulation during the initial stage of ALF. Our study provides new data supporting the concept of glutamate deficiency in a pig model of ALF. Furthermore, the kidneys are quantitatively as important as PDV in ammonia production, and the muscles play an important role in ammonia removal.

Ammonia↗

PubMed2002

Comparison of the effects of ammonia on brain mitochondrial function in rats and gulf toadfish.

We compared the effect of hyperammonemia on NADH levels in brain slices and on the rate of oxygen consumption from isolated nonsynaptic brain mitochondria in ammonia-sensitive Wistar rats with that in ammonia-tolerant gulf toadfish (Opsanus beta). The NADH content was significantly decreased (12% less than control after 45 min with 1 mM NH(4)Cl) in rat brain slices, but it was not affected in brain slices from toadfish (with both 1 and 6 mM NH(4)Cl). The rates of oxygen consumption of different sets of enzymes of the electron transport chain (ETC; complexes I, II, III, and IV; II, III, and IV; and IV alone) were unaltered by hyperammonemic conditions in isolated nonsynaptic mitochondria from either rats or toadfish. These results lead us to conclude that the differing effects of ammonia on NADH levels in rat and toadfish brain slices must be due to aspects other than the direct effects of ammonia on enzymes of the ETC. Additionally, because these effects were seen in vitro, our studies enabled us to rule out the possibility that effects of ammonia on metabolism were via indirect systemic effects. These results are discussed in the context of current views on mechanisms of central nervous system damage in hyperammonemic states.

Ammonia↗

PubMed2003

Neonatal seizures: the overlap between diagnosis of metabolic disorders and structural abnormalities. Case report.

UNLABELLED: Inborn metabolic errors (IME) and cortical developmental malformations are uncommon etiologies of neonatal seizures, however they may represent treatable causes of refractory epilepsy and for this reason must be considered as possible etiological factors. This case report aims to demonstrate the importance of neuroimaging studies in one patient with neonatal seizures, even when there are clues pointing to a metabolic disorder. CASE REPORT: A previously healthy 14 day-old child started presenting reiterated focal motor seizures (FMS) which evolved to status epilepticus. Exams showed high serum levels of ammonia and no other abnormalities. A metabolic investigation was conducted with normal results. During follow-up, the patient presented developmental delay and left side hemiparesia. Seizures remained controlled with anti-epileptic drugs for four months, followed by relapse with repetitive FMS on the left side. Temporary improvement was obtained with anti-epileptic drug adjustment. At the age of 6 months, during a new episode of status epilepticus, high ammonia levels were detected. Other metabolic exams remained normal. The child was referred to a video-electroencephalographic monitoring and continuous epileptiform discharges were recorded over the right parasagittal and midline regions, with predominance over the posterior quadrant. A new neuroimaging study was performed and displayed a malformation of cortical development. Our case illustrates that because newborns are prone to present metabolic disarrangement, an unbalance such as hyperammonemia may be a consequence of acute events and conduct to a misdiagnosis of IME.

Cerebral Cortex↗

PubMed2002

Recovery from marked altered consciousness in a patient with adult-onset type II citrullinemia diagnosed by DNA analysis and treated with a living related partial liver transplantation.

A 21-year-old woman was admitted with altered consciousness and hyperammonemia. She was diagnosed as having adult-onset type II citrullinemia (CTLN2) by DNA analysis. The patient had mutations of the SLC25A13 gene, which were compound heterozygotes of 851 del 4 and IVS11+1G>A. CTLN2 has a poor prognosis, in spite of various intensive medications, and we performed a living related partial liver transplantation (LRLT). Over a 2-year follow-up, the patient has been well. CTLN2 can be diagnosed by the DNA analysis and can be treated by LRLT.

Adult↗

PubMed2007

Glutamine in the central nervous system: function and dysfunction.

Glutamine (Gln) abounds in the central nervous system (CNS), and its interstitial and cerebrospinal fluid (CSF) concentrations are at least one order of magnitude higher than of any other amino acid. Gln transport from blood to the brain is insufficient to meet the demand of the brain tissues for this amino acid. This demand is met by intracerebral Gln synthesis from glutamate (Glu), a reaction carried out by glutamine synthetase (GS), an enzyme residing in astrocytes. A major proportion of astroglia-derived Gln is shuttled to neurons where it is degraded by phosphate-activated glutaminase (PAG) giving rise to the excitatory neurotransmitter amino acid Glu, which is also a precursor of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA). Glu released from neurons is taken up by astrocytes, and reconverted to Gln, closing the so called "glutamate-glutamine" cycle. A portion of Gln serves as an energy metabolite, and part of it leaves the brain to blood. Gln efflux from astrocytes, its neuronal uptake and egress to the blood via the cerebral capillary endothelial cells is mediated by different amino acid carriers showing i) considerable preference for Gln, ii) distribution between astrocytes and neurons that favors astrocyte-to-neuron fluxes of the amino acid. The Gln-specific carriers also largely contribute to Gln efflux from the brain to the vascular bed. Excessive accumulation of Gln in brain cells may be deleterious to brain function. In hyperammonemia associated with acute liver failure, excess Gln leads to cerebral edema, which largely results from its interference with mitochondrial function and partly from its osmotic action. Future analyses of the roles of Gln in both normal and abnormal cerebral metabolism and function will have to account for its newly recognized direct involvement in the regulation of gene transcription and/or translation.

Animals↗

PubMed2001

Establishment of CD7+ human myeloma sister cell lines, KMS-21-PE and KMS-21-BM, carrying t(11;14) and t(8;14).

Two new human myeloma cell lines were established from pleural effusion and bone marrow malignant cells derived from a single patient, who manifested hyperammonemia associated with multiple myeloma, and these were characterized. Both lines possess t(11;14)(q13;q32) and t(8;14)(q24;q32) reciprocal translocations and overexpress cyclin D1, but not c-myc. Human myeloma lines including these new lines produced and secreted excess ammonia into culture medium more than non-myelomatous hematological cell lines. In addition, these two lines were revealed to have high surface CD7 expression correlated with relatively high mRNA expression by MP-RT-PCR. Among 8 human myeloma lines, half of them revealed significant surface expression of CD7 and a positive correlation between expression levels of protein and message. CD7 message was also detected in surface negative lines. Consequently, there may be posttranslational regulation of the CD7 molecule, whose cellular biological role in expressing cells has not been elucidated.

Adult↗

PubMed2003

Brain MR imaging in acute hyperammonemic encephalopathy arising from late-onset ornithine transcarbamylase deficiency.

The brain MR imaging characteristics of three patients with acute hyperammonemic encephalopathy resulting from late-onset ornithine transcarbomylase deficiency are presented. MR images revealed injury to the cortex, especially the cingulate gyrus and insular cortex, with sparing of the perirolandic and occipital cortices. These findings presumably reflect the distribution of brain injury from hypoperfusion secondary to hyperammonemia. Knowledge of the MR findings may help expedite diagnosis and treatment and prevent chronic impairment.

Brain↗

PubMedDate not supplied

[Ring chromosome 20, hypersensitivity to valproate and hyperammonemic encephalopathy].

INTRODUCTION: Ring chromosome 20 syndrome (C20A) is characterised by mental retardation, behavioural disorders, dysmorphias and refractory epilepsy with polymorphic seizures. It should therefore be treated with broad-spectrum antiepileptic drugs (AEDs), such as valproate (VPA) and topiramate (TPM). The relatively frequent hypersensitivity reactions to aromatic AEDs, not to VPA, the hyperammonemic encephalopathy (HAE) caused by the combination of VPA and TPM and the chromosome disorder described, affecting the same patient, do not appear in the literature we reviewed. CASE REPORT: A patient aged 5 years who, at the age of 11 months, was seen to have psychomotor retardation, microcephaly, plagiocephaly, facial dysmorphia and hypotonia. At 26 months, the patient presented seizures with fever, sucking, perioral cyanosis, clonisms in the upper extremities and hypotonia. Karyotype: C20A, with no mosaicism. Treatment was started with VPA up to 600 mg/day, and moderate eosinophilia appeared from 450 mg/day onwards. At the age of 4 years, the patient suffered partial complex seizures, which stopped with the addition of TPM. At the same age there was also anorexia, loss of weight, adynamia, hypotonia, drowsiness, confusion, increased eosinophilia (20.3%) and IgE and a rash caused by the VPA. The clinical features yielded on adding dexchlorpheniramine. Nine months later, apathy, adynamia, eosinophilia and hyperammonemia reappeared; we therefore reduced and later stopped administration of VPA, although TPM was maintained. CONCLUSIONS: No relation between hypersensitivity to VPA, HAE and C20A has been described. The VPA TPM combination was effective, but in the end we had to stop administering VPA because of hypersensitivity and the side effects (HAE) of the combination.

Anticonvulsants↗

PubMed2005

Valproate-induced encephalopathy.

Valproate-induced encephalopathy is a rare syndrome that may manifest in otherwise normal epileptic individuals. It may even present in patients who have tolerated this medicine well in the past. It is usually but not necessarily associated with hyperammonemia. The EEG shows characteristic triphasic waves in most patients with this complication. A case of valproate-induced encephalopathy is presented. The problems in diagnosing this condition are subsequently discussed.

Aged↗