Plasma Ammonia Levels Research Articles

Oral Bioavailability Enhancement and Anti-Fatigue Assessment of the Andrographolide Loaded Solid Dispersion.

Andrographolide (AG), a major diterpene lactone isolated from Andrographis paniculata (Burm. f.) Nees (Acanthaceae), possesses a wide spectrum of biological activities. However, its poor water solubility and low bioavailability limit its clinical application. Therefore, this study aimed to develop a solid dispersion (SD) formulation to increase the aqueous solubility and dissolution rate of AG. Different drug-polymer ratios were used to prepare various SDs. The optimized formulation was characterized for differential scanning calorimetry, Fourier transform infrared spectroscopy, and powder X-ray diffraction. The analysis indicated that the optimized SD enhanced AG solubility and dissolution rates by changing AG crystallinity to an amorphous state. The dissolution behaviors of the optimum SD composed of an AG-polyvinylpyrrolidone K30-Kolliphor EL ratio of 1:7:1 (w/w/w) resulted in the highest accumulated dissolution (approximately 80%). Pharmacokinetic studies revealed that Cmax/dose and the AUC/dose increased by 3.7-fold and 3.0-fold, respectively, compared with AG suspension. Furthermore, pretreatment using the optimized AG-SD significantly increased the swimming time to exhaustion by 1.7-fold and decreased the plasma ammonia level by 71.5%, compared with the vehicle group. In conclusion, the optimized AG-SD formulation appeared to effectively improve its dissolution rate and oral bioavailability. Moreover, the optimized AG-SD provides a promising treatment against physical fatigue.

VALPROATE-INDUCED HYPERAMMONEMIC ENCEPHALOPATHY IN A CHILD WITHOUT HEPATIC FAILURE: A CASE REPORT

Sodium valproate or valproic acid (VPA) is an effective antiepileptic drug that is commonly used for epilepsy in children because of its broad-spectrum activity. The use of VPA frequently results in elevated plasma levels of ammonia with or without raised transaminases. This condition usually happens when VPA with polypharmacy or underlying metabolic disorders like urea cycle defects. We are reporting a case of valproate-induced hyperammonemic encephalopathy in a child which is rare in children. Health professionals should be aware of this potential complication, and it is highly recommended to check ammonia levels in patients taking VPA who present with a change in mental status. If identified early, it can treat with appropriate measures and it can reversible.

High ambient temperature increases the toxicity and lethality of 3,4-methylenedioxymethamphetamine and methcathinone

RationaleMethylenedioxymethamphetamine (MDMA) and methcathinone (MCAT) are abused psychostimulant drugs that produce adverse effects in human users that include hepatotoxicity and death. Recent work has suggested a connection between hepatotoxicity, elevations in plasma ammonia, and brain glutamate function for methamphetamine (METH)-induced neurotoxicity. ObjectivesThese experiments investigated the effect of ambient temperature on the toxicity and lethality produced by MDMA and MCAT in mice, and whether these effects might involve similar mechanisms to those described for METH neurotoxicity. ResultsUnder low (room temperature) ambient temperature conditions, MDMA induced hepatotoxicity, elevated plasma ammonia levels, and induced lethality. Under the same conditions, even a very high dose of MCAT produced limited toxic or lethal effects. High ambient temperature conditions potentiated the toxic and lethal effects of both MDMA and MCAT. ConclusionThese studies suggest that hepatotoxicity, plasma ammonia, and brain glutamate function are involved in MDMA-induced lethality, as has been shown for METH neurotoxicity. The toxicity and lethality of both MDMA and MCAT were potentiated by high ambient temperatures. Although an initial mouse study reported that several cathinones were much less toxic than METH or MDMA, the present results suggest that it will be essential to assess the potential dangers posed by these drugs under high ambient temperatures.

Hyperinsulinism associated with GLUD1 mutation: allosteric regulation and functional characterization of p.G446V glutamate dehydrogenase

BackgroundGain-of-function mutations in the GLUD1 gene, encoding for glutamate dehydrogenase (GDH), result in the hyperinsulinism/hyperammonemia HI/HA syndrome. HI/HA patients present with harmful hypoglycemia secondary to protein-induced HI and elevated plasma ammonia levels. These symptoms may be accompanied by seizures and mental retardation. GDH is a mitochondrial enzyme that catalyzes the oxidative deamination of glutamate to α-ketoglutarate, under allosteric regulations mediated by its inhibitor GTP and its activator ADP. The present study investigated the functional properties of the GDH-G446V variant (alias c.1496G > T, p.(Gly499Val) (NM_005271.4)) in patient-derived lymphoblastoid cells.ResultsThe calculated energy barrier between the opened and closed state of the enzyme was 41% lower in GDH-G446V compared to wild-type GDH, pointing to altered allosteric regulation. Computational analysis indicated conformational changes of GDH-G446V in the antenna region that is crucial for allosteric regulators. Enzymatic activity measured in patient-derived lymphoblastoid cells showed impaired allosteric responses of GDH-G446V to both regulators GTP and ADP. In particular, as opposed to control lymphoblastoid cells, GDH-G446V cells were not responsive to GTP in the lower range of ADP concentrations. Assessment of the metabolic rate revealed higher mitochondrial respiration in response to GDH-dependent substrates in the GDH-G446V lymphoblastoid cells compared to control cells. This indicates a shift toward glutaminolysis for energy provision in cells carrying the GDH-G446V variant.ConclusionsSubstitution of the small amino acid glycine for the hydrophobic branched-chain valine altered the allosteric sensitivity to both inhibitory action of GTP and activation by ADP, rendering cells metabolically responsive to glutamine.

Allosteric Regulation of Glutamate Dehydrogenase

Glutamate dehydrogenase (GDH) catalyzes the oxidative deamination of L-glutamate to α-ketoglutarate and, in animals, is allosterically regulated by a wide array of metabolites. The role of this complex allosteric regulation was made evident by hyperinsulinism/hyperammonemia syndrome (HHS). In HHS, mutations desensitize GDH to allosteric inhibition by GTP leading to excessive insulin secretion, increase in plasma ammonium levels, and dysregulation of glutamate levels in the brain leading to seizures and developmental delays. The current treatment for HHS is the potassium channel activator, diazoxide, which only addresses the hyperinsulinism aspect of the disease. Only by targeting GDH directly can all of the multi-organ symptoms of HHS be addressed. We have just screened more than 250,000 compounds for both activators and inhibitors of GDH. These compounds will not only have direct clinical applications for treating HHS but will elucidate the atomic details of GDH regulation. In the case of the latter, we have also deleted the unusual 50-residue ‘antenna’ feature of the enzyme and are finding that it plays a fundamental role in catalytic turnover in rather unexpected ways.

Is ammonia excretion affected by gill ventilation in the rainbow trout Oncorhynchus mykiss?

Ammonia (NH3 + NH4+) is the major nitrogenous waste in teleost fish. NH3 is also the third respiratory gas, playing a role in ventilatory control. However it is also highly toxic. Normally, ammonia excretion through the gills occurs at about the same rate as its metabolic production, but the branchial transport mechanisms have long been controversial. An influential review in this journal has claimed that ammonia excretion in fish is probably limited by diffusion rather than by convection, so that increases in ventilation would have negligible effect on the rate of ammonia excretion. Why then should elevated plasma ammonia stimulate ventilation? The diffusion-limitation argument was made before the discovery of Rhesus (Rh) glycoproteins and the associated metabolon in the gills, which serve to greatly increase branchial ammonia permeability under conditions of ammonia loading. Therefore, we hypothesized here that (i) in accord with the diffusion-limitation concept, changes in ventilation would not affect the rate of ammonia excretion under conditions where branchial Rh metabolon function would be low (resting trout with low plasma ammonia levels). However, we also hypothesized that (ii) in accord with convective limitation, changes in ventilation would influence the rate of ammonia excretion under conditions where diffusion limitation was removed because branchial Rh metabolon function would be high (ammonia-loaded trout with high plasma ammonia levels). We used variations in environmental O2 levels to manipulate ventilation in trout under control or ammonia-loaded conditions – i.e. hyperventilation in moderate hypoxia or hypoventilation in moderate hyperoxia. In accord with hypothesis (i), under resting conditions, ammonia excretion was insensitive to experimentally induced changes in ventilation. Ammonia-loading by NH4HCO3 infusion for 30h + increased the gill mRNA expressions of two key metabolon components (Rhcg2, V-H+-ATPase or HAT), together with a 7.5-fold increase in plasma ammonia concentration and a 3-fold increase in ammonia excretion rate. In accord with hypothesis (ii), in these fish, hypoxia-induced increases in ventilation elevated the ammonia excretion rate and lowered plasma ammonia, while hyperoxia-induced decreases in ventilation reduced the ammonia excretion rate, and elevated plasma ammonia concentration. We conclude that under conditions of natural ammonia loading (e.g. meal digestion, post-exercise recovery), diffusion-limitation is removed by Rh metabolon upregulation, such that the stimulation of ventilation by elevated plasma ammonia can play an important role in clearing the potentially toxic ammonia load.

Role of dihydroceramides in the progression of acute-on-chronic liver failure in rats.

BackgroundPreviously, dihydroceramide (d18:0/24:0) (dhCer (d18:0/24:0)) was reported to be a potential biomarker for acute-on-chronic liver failure (ACLF) prognosis. In this study, we further explored the role of dhCer (d18:0/24:0) in the progression of ACLF to validate the biomarker using ACLF rat model.MethodsACLF rats were sacrificed at 4 and 8 h post-D-galactosamine (D-gal)/lipopolysaccharide (LPS) administration to investigate the liver biochemical markers, prothrombin time and liver histopathology. Change in dhCer and other sphingolipids levels were investigated by high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS). Rats were treated with N-(4-hydroxyphenyl) retinamide (4-HPR) to examine the mortality rate and its role in improving ACLF.ResultsLPS/D-gal administration resulted in significant elevation in alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels. Prothrombin time was prolonged and histopathological examination showed abnormality. HPLC-MS/MS results showed total dhCer levels in ACLF group (64.10 ± 8.90 pmol/100 μL, 64.22 ± 6.78 pmol/100 μL for 4 and 8 h, respectively) were decreased significantly compared with control group (121.61 ± 23.09 pmol/100 μL) (P < 0.05). In particular, dhCer (d18:0/24:0), dhCer (d18:0/20:0), and dhCer (d18:0/22:0) levels were decreased. Treatment with 4-HPR significantly increased the levels of dhCers, including dhCer (d18:0/24:0) compared with ACLF group, for the level of dhCer (d18:0/24:0) in 4-HPR group was 20.10 ± 8.60 pmol/100 μL and the level of dhCer (d18:0/24:0) in ACLF group was 9.74 ± 2.99 pmol/100 μL (P < 0.05). This was associated with reduced mortality rate and prolonged survival time. The ALT and AST in 4-HPR group were significantly decreased compared with ACLF group. The prothrombin time of 4-HPR group (41.49 s) was significantly lower than the prothrombin time of ACLF group (57.96 s) (P < 0.05). 4-HPR also decreased plasma ammonia levels slightly, as the plasma ammonia levels in 4-HPR group and ACLF group were 207.37 ± 60.43, 209.15 ± 60.43 μmol/L, respectively. Further, 4-HPR treatment improved histopathological parameters.ConclusionsDhCer, especially dhCer (d18:0/24:0), is involved in the progression of ACLF. Increasing the levels of dhCer can reduce the mortality rate of ACLF rats and alleviate liver injury.

Upregulation of ureagenesis may be pivotal for survival of post-hepatectomy liver failure in rats

Background: Post-hepatectomy liver failure (PHLF) is a feared complication with high mortality that may occur after extended partial hepatectomy (PH). Due to the risk of PHLF, size of PH and hence the size of the future liver remnant (FLR) may limit curability if malignancy is widespread in the liver. With the aim to identify proteins specific to the regenerative process of minimal-size FLR (MSFLR) and during PHLF, we characterized protein expressions on different PODs by sizes of PH. Material & Methods: A total of 104 male Wistar rats subjected to 30%, 70%, or 90% PH (MSFLR in rats); sham or no operation. Blood and liver tissue harvested at POD1, 3, and 5 (n=8 per group). Protein expression was assessed by unsupervised proteomic profiling by 2D-PAGE and liquid-chromatography mass-spectrometry. In addition, plasma-ammonia levels were measured at time of euthanization. Results: In all,1,035 protein spots were identified of which 54 were significantly differentially expressed between groups (FDR<0.05, fold change>2) and identifiable. Strikingly, during PHLF, represented by the PH(90%) POD1-group, specifically protein expressions favoring urea cycle activity were changed by upregulation of Carbamoyl phosphate synthase-1 (CPS-1), Ornithine transcarbamylase (OTC) and Arginase-1 (ARG-1) with coexisting downregulation of Ornithine aminotransferase (OAT) and Propionyl-CoA carboxylase alpha chain (PCCA)(Fig. 1). Plasma-ammonia was highly elevated at POD1 after PH(90%) followed by a prompt decrease (Fig. 1). Conclusions: The protein expression of the MSFLR of surviving rats during PHLF is changed in favor of urea cycle enhancement. Our Results indicate that ammonia elimination by enhanced urea-cycle capacity in hepatocytes plays a key role in survival after extensive PHs and potential PHLF.

Quantification of urinary derivatives of Phenylbutyric and Benzoic acids by LC-MS/MS as treatment compliance biomarkers in Urea Cycle disorders

PurposeSalts of phenylacetic acid (PAA) and phenylbutyric acid (PBA) have been used for nitrogen elimination as a treatment for hyperammonaemia caused by urea cycle disorders (UCD). A new analytical method for PBA measurement in urine which helps to evaluate the drug adherence has been implemented. MethodsUrine specimens from UCD patients receiving PBA were analysed by tandem mass spectrometry to measure urine phenylacetylglutamine (PAGln). Some clinical and biochemical data for each patient were collected. ResultsOur study included 87 samples from 40 UCD patients. The PAGln levels did not correlate with height, weight or age. However, the PAGln values showed correlation with PBA dose (r = 0.383, P = 0.015). Plasma glutamine and ammonia levels presented a positive correlation (r = 0.537, P < 0.001). The stability for PAGln in urine was determined at different storage temperatures. ConclusionsWe have developed a simple method for the determination of PAGln in urine, which acts as useful biomarker of effective drug delivery. PAGln in urine is stable at room temperature at least for 15 days, and for several months when frozen at -20 °C. This procedure is useful for the optimization and monitorization of the drug dose allowing the use of spot urine samples.

Effects of BCAA Enteral Nutrition to the Change of Nutritional Status and Hepatic Encephalopathy Parameters in Liver Cirrhosis Patient with Hepatic Encephalopathy

Background: This study was also conducted to determine the effects of high-branched chain amino acid (BCAA) enteral supplementation on altered nutritional status parameters (including plasma prealbumin) and hepatic encephalopathy parameters in liver cirrhosis patients with hepatic encephalopathy. Method: Our study was a randomized, single-blinded experimental study comparing between control group of liver cirrhosis patients with standard hospital liver diet (40 kcal/kgBW/day for male and 35 kcal/kgBW/day for female; protein 1.25 g/kgBW/day) and experimental group of liver cirrhosis patients with liver diet modification high in BCAA supplementation, which had similar protein and calorie calculation as the control group. Results: Subclinical hepatic encephalopathy prevalence was 32%. In the experimental group, prealbumin plasma, arm circumference, body weight and body mass index (BMI) increased; whereas in the control group, prealbumin plasma, arm circumference, body weight and BMI decreased (p < 0.05). In experimental group, the ammonia level significantly decreased (p < 0.01). Clinical hepatic encephalopathy, flapping tremor, the number connection test (NCT) did not show significant changes between the two groups. However, there was worsening trend in the control group. Level of albumin, bilirubin, AST, ALT did not show any significant difference between both groups. Conclusion: High-BCAA enteral supplementation which is administered to liver cirrhosis patients with hepatic encephalopathy for 14 days could improve plasma prealbumin level, arm circumference, body weight, BMI and could decrease the plasma ammonia level. However, it does not improve Fischer ratio, psychometric test and electroencephalography Keywords: malnutrition, liver cirrhosis, BCAA, Fisher ratio

Transdermal fennel essential oil nanoemulsions with promising hepatic dysfunction healing effect: in vitro and in vivo study

Fennel (Foeniculum vulgare Mill.) is a member of family Apiaceae. Trans-anethole, the major component of Fennel essential oil (FEO), possesses antioxidant and hepatoprotective effects. Transdermal nanoemulsions (NEs) are advanced colloidal systems for systemic and controlled drug delivery through the stratum corneum barrier. FEO NEs were prepared using the oil Lauroglycol™ 90, as it provides a larger NE existence zone than Captex® 300, in the constructed phase diagrams. Six systems were prepared using Tween20/propylene glycol (S/CoS) in the ratios 2:1 and 3:1 with oil to S/CoS mass ratios 1:9, 2:8 and 3:7. Physicochemical characterization revealed optimum properties regarding thermodynamic stability, droplet size and pH with a Newtonian flow pattern. In vitro permeation study in rat skin revealed the highest cumulative amount permeated (µg/cm2), flux and permeability coefficient values for F4 made up of 2% FEO, 4.67% Lauroglycol™ 90, 60% S/CoS in the ratio 3:1. Results of the in vivo hepatic dysfunction study in rats indicate promising significant amelioration of liver function reflected in ALT, AST, ALP, bilirubin, albumin, malondialdehyde and ammonia plasma levels. The results signify the promising approach of FEO NEs in achieving remedy of liver toxicity. The most promising effect is inherent to F4 which imparts a more positive effect than FEO.

Does dissolved organic carbon from Amazon black water (Brazil) help a native species, the tambaqui Colossoma macropomum to maintain ionic homeostasis in acidic water?

To assess how the quality and properties of the natural dissolved organic carbon (DOC) could drive different effects on gill physiology, we analysed the ionoregulatory responses of a native Amazonian fish species, the tambaqui Colossoma macropomum, to the presence of dissolved organic carbon (DOC; 10 mg l-1 ) at both pH 7.0 and pH 4.0 in ion-poor water. The DOC was isolated from black water from São Gabriel da Cachoeira (SGC) in the upper Rio Negro of the Amazon (Brazil) that earlier been shown to protect a non-native species, zebrafish Danio rerio against low pH under similar conditions. Transepithelial potential (TEP), net flux rates of Na+ , Cl- and ammonia and their concentrations in plasma and Na+ , K+ ATPase; v-type H+ ATPase and carbonic anhydrase activities in gills were measured. The presence of DOC had negligible effects at pH 7.0 apart from lowering the TEP, but it prevented the depolarization of TEP that occurred at pH 4.0 in the absence of DOC. However, contrary to our initial hypothesis, SGC DOC was not protective against the effects of low pH. Colossoma macropomum exposed to SGC DOC at pH 4.0 experienced greater net Na+ and Cl- losses, decreases of Na+ and Cl- concentrations in plasma and elevated plasma ammonia levels and excretion rates, relative to those exposed in the absence of DOC. Species-specific differences and changes in DOC properties during storage are discussed as possible factors influencing the effectiveness of SGC DOC in ameliorating the effects of the acid exposure.

Prognostic Role of Ammonia in Patients With Cirrhosis.

Ammonia is thought to be central to the pathogenesis of hepatic encephalopathy (HE), but its prognostic role in patients with cirrhosis and acute decompensation is unknown. The aims of this study were to determine the relationship between ammonia levels and severity of HE and its association with organ dysfunction and short-term mortality. We identified 498 patients from two institutions as part of prospective observational studies in patients with cirrhosis. Plasma ammonia levels were measured on admission and Chronic Liver Failure-Sequential Organ Failure Assessment criteria were used to determine the presence of organ failures. The 28-day patient survival was determined. Receiver operating characteristic analysis was used to identify the cutoff points for ammonia values, and multivariable analysis was performed using the Cox proportional hazard regression model. The 28-day mortality was 43.4%. Plasma ammonia correlated with severity of HE (P < 0.001), was significantly higher in nonsurvivors (93 [73-121] versus 67 [55-89] µmol/L, P < 0.001), and was an independent predictor of 28-day mortality (hazard ratio, 1.009, P < 0.001). An ammonia level of 79.5 µmol/L had sensitivity of 68.1% and specificity of 67.4% for predicting 28-day mortality. An ammonia level of ≥79.5 µmol/L was associated with a higher frequency of organ failures (liver [P = 0.004], coagulation [P < 0.001], kidney [P = 0.004], and respiratory [P < 0.001]). Lack of improvement in baseline ammonia at day 5 was associated with high mortality (70.6%). Conclusion: Ammonia level correlates with not only the severity of HE but also the failure of other organs and is an independent risk factor for mortality; lack of improvement in ammonia level is associated with high risk of death, making it an important biomarker and a therapeutic target.

Short-term results of continuous venovenous haemodiafiltration versus peritoneal dialysis in 40 neonates with inborn errors of metabolism

Several recent studies have reported that toxic metabolites accumulated in the body as a product of inborn errors of metabolism (IEM) are eliminated more rapidly with continuous venovenous hemodiafiltration (CVVHDF) than with peritoneal dialysis (PD). However, there is still uncertainty about the impacts of dialysis modalities on the short-term outcome. Here, it was aimed to investigate the effects of dialysis modalities on the short-term outcome. This retrospective study included 40 newborn infants who underwent PD (29 patients) or CVVHDF (11 patients) due to inborn errors of metabolism at a tertiary centre, between June 2013 and March 2018. The outcomes and the potential effects of the dialysis modality were evaluated. Of 40 patients, 21 were urea cycle defect, 14 were organic academia, and 5 were maple syrup urine disease. The median 50% reduction time of toxic metabolites were shorter in patients treated with CVVHDF (p < 0.05). Catheter blockage was the most common complication observed in PD group (24.1%), whereas in CVVHDF group hypotension and filter blockage were more common. There was no significant difference in mortality between dialysis groups (38% vs. 45.4%, p > 0.05). In patients with hyperammonaemia, duration of plasma ammonia > 200μg/dL was the most important factor influencing mortality (OR 1.05, CI 1.01-1.09, p = 0.007).Conclusion: This study showed that CVVHDF is more efficient than PD to rapidly eliminate toxic metabolites caused by IEM in newborn infants, but not in improving survival. What is Known: •Toxic metabolites are eliminated more rapidly with CVVHDF than with PD. •Higher complication rates were reported with rigid peritoneal catheters in PD and catheter blockage in CVVHDF. What is New: •Prolonged duration of plasma ammonia levels above a safe limit (200 μg/dL) was associated with increased mortality. •Lower catheter-related complication rates may have been associated with the use of Tenckhoff catheters in PD and the use of right internal jugular vein in CVVHDF.

Efficacy of peritoneal dialysis in neonates presenting with hyperammonaemia due to urea cycle defects and organic acidaemia.

Newborns with inborn errors of metabolism can present with hyperammonaemic coma. In this study, we evaluated the effect of peritoneal dialysis on plasma ammonium levels and on the short-term outcome in neonatal patients with urea cycle defects and organic acidaemia. Data from infants with hyperammonaemia due to urea cycle defects or organic acidaemia treated with dialysis were collected and retrospectively analyzed. The results of patient groups (group I, survived; and group II, died) were compared. Fourteen neonates were enrolled in this study. In group I, plasma ammonium levels before dialysis were median (IQR) 1652 μg/dL (1165-2098 μg/dL); in group II, they were 1289 μg/dL (1070-5550 μg/dL). There was no statistically significant difference. Urea cycle defects were diagnosed in eight, and organic acidaemia in six patients. The duration of a blood ammonia level >200 μg/dL was longer in group II (P = 0.04). A <60.8% decline in the ammonia level from the beginning of dialysis to the 12th hour of dialysis carried a 3.33-fold higher risk of mortality, when compared with a greater decline. Five patients with urea cycle defects, and one with organic acidaemia, died. The mortality risk was 8.33-fold (95% CI = 0.63-90.86) higher for patients with urea cycle defects than for those with organic acidaemia. In patients with hyperammonaemia treated with peritoneal dialysis, the rate of ammonia removal and the underlying aetiology appear to be important prognostic factors. Neonates with organic acidaemia who are admitted to centres without continuous renal replacement therapy facilities can be effectively treated with peritoneal dialysis.

Argininosuccinic aciduria: Recent pathophysiological insights and therapeutic prospects.

The first patients affected by argininosuccinic aciduria (ASA) were reported 60 years ago. The clinical presentation was initially described as similar to other urea cycle defects, but increasing evidence has shown overtime an atypical systemic phenotype with a paradoxical observation, that is, a higher rate of neurological complications contrasting with a lower rate of hyperammonaemic episodes. The disappointing long-term clinical outcomes of many of the patients have challenged the current standard of care and therapeutic strategy, which aims to normalize plasma ammonia and arginine levels. Interrogations have raised about the benefit of newborn screening or liver transplantation on the neurological phenotype. Over the last decade, novel discoveries enabled by the generation of new transgenic argininosuccinate lyase (ASL)-deficient mouse models have been achieved, such as, a better understanding of ASL and its close interaction with nitric oxide metabolism, ASL physiological role outside the liver, and the pathophysiological role of oxidative/nitrosative stress or excessive arginine treatment. Here, we present a collaborative review, which highlights these recent discoveries and novel emerging concepts about ASL role in human physiology, ASA clinical phenotype and geographic prevalence, limits of current standard of care and newborn screening, pathophysiology of the disease, and emerging novel therapies. We propose recommendations for monitoring of ASA patients. Ongoing research aims to better understand the underlying pathogenic mechanisms of the systemic disease to design novel therapies.

Carglumic acid in hyperammonaemia due to organic acidurias: a profile of its use in the EU

Carglumic acid (N-carbamylglutamate; Carbaglu®), a structural analog of N-acetylglutamate, is an effective and generally well-tolerated option for the treatment of hyperammonaemia due to propionic, methylmalonic and isovaleric acidurias. These organic acidurias are linked to a group of autosomal recessive inherited disorders that are associated with secondary hyperammonaemia due to the inhibition of the urea cycle. Carglumic acid can be administered orally or through a nasogastric tube. In retrospective, observational studies and case series/reports, carglumic acid rapidly reduced plasma ammonia levels and improved clinical symptoms of hyperammonaemia. Carglumic acid is generally well tolerated, and, based on limited data, may be associated with fewer treatment-emergent adverse events when used in combination with ammonia scavengers than when either therapy is administered alone.

Protective effect of high hardness in pacu juveniles (Piaractus mesopotamicus) under acidic or alkaline pH: Biochemical and haematological variables

The relationship between water pH and hardness influences fish physiology, where increasing water hardness could trigger a protective effect for fish exposed to acidic or alkaline pH. Hence, this study aimed to investigate pacu (Piaractus mesopotamicus) for the existence of a protective effect of high water hardness at acidic and alkaline pH. Pacu exemplars were exposed to low (LWH, 50 mg CaCO3 L−1) or high water hardness (HWH, 120 mg CaCO3 L−1) at acidic (5.5), circumneutral (7.5) or alkaline (9.0) pH, for 15 days. Un-ionised ammonia was the highest at the alkaline pH, and alkalinity was the lowest at the acidic pH. Blood pH levels were lowest at alkaline pH, mainly when fish were subjected to HWH. The HWH presented a protective effect for pacu exposed to acidic or alkaline pH, as verified in the blood glucose and lactate, and plasma total ammonia levels on day 1, total plasma protein levels on day 5, and total ammonia and alkaline phosphatase levels in plasma on day 15. Values of haematocrit, haemoglobin and haematimetric indices, were typically increased in fish exposed to alkaline or acidic pH in LWH throughout the experiment, which, in turn, was not verified for fish exposed to HWH. In conclusion, pacu can cope with acidic or alkaline conditions, but acidic and alkaline pHs under LWH are stressful. The combination of acidic or alkaline pH with HWH triggered a protective effect because biochemical and haematological variables of pacu juveniles showed few changes in fish exposed to circumneutral pH.

Acute pediatric hyperammonemia: current diagnosis and management strategies.

Acute hyperammonemia may induce a neurologic impairment leading to an acute life-threatening condition. Coma duration, ammonia peak level, and hyperammonemia duration are the main risk factors of hyperammonemia-related neurologic deficits and death. In children, hyperammonemia is mainly caused by severe liver failure and inborn errors of metabolism. In an acute setting, obtaining reliable plasma ammonia levels can be challenging because of the preanalytical difficulties that need to be addressed carefully. The management of hyperammonemia includes 1) identification of precipitating factors and cerebral edema presence, 2) a decrease in ammonia production by reducing protein intake and reversing catabolism, and 3) ammonia removal with pharmacologic treatment and, in the most severe cases, with extracorporeal therapies. In case of severe coma, transcranial Doppler ultrasound could be the method of choice to noninvasively monitor cerebral blood flow and titrate therapies.

Abstract P-246: CONTINUOUS RENAL REPLACEMENT THERAPY IN NEONATES WITH HYPERAMMONEMIA

Aims & Objectives: Hyperammonemia in neonates can cause neurotoxic symptoms, and continuous renal replacement therapy (CRRT) is useful modality for the critical care of neonates with hyperammonemia caused by inborn errors of metabolism (IEM). The aim of this study is to evaluate the outcomes of CRRTand the prescriptions of CRRT to effectively reduce the plasma levels of ammonia in neonates with hyperammonemia. Methods The medical records of 12 Korean neonates with IEM who underwent CRRT for hyperammonemia from January 2008 to December 2016 were retrospectively analyzed. Results The median age of neonatal intensive care unit admission due to hyperammonemia was 4 days, and 2 patients were preterm babies. Male to female ratio was 2:1. The final diagnosis for hyperammonemia included ornithine transcarbamylase deficiency (n=4), citrullinemia (n=4), carbamoyl phosphate synthetase deficiency (n=2), and propionic academia (n=2). All patients received continuous veno-venous hemodiafiltration. The median blood flow rate at the initiation of CRRT was 9.6 ml/kg/min. The median ultrafiltration rate (UFR) at the initiation of CRRT was 2,448 ml/hr/1.73m2, and increased up to the median levels of 3,456 ml/hr/1.73m2. The median duration of CRRT was 4.5 days. The median plasma ammonia level at CRRT initiation was 1115.8 umol/L. The median value of estimated half time for plasma ammonia level after CRRT was 12.8 hour. Six patients restarted CRRT because of rebound hyperammonemia, and the survival rate was 83.3%. Conclusions This study suggested that CRRT could be a therapeutic option for neonates with IEM, and patients with high plasma ammonia levels need to increase UFR above 4000ml/hr/1.73m2.