Systemic and regional hemodynamics in pigs with acute liver failure and the effect of albumin dialysis

Acute liver failure

Acute liver failure (ALF) is a life-threatening disorder characterised by rapid deterioration of liver function, coagulopathy, and hepatic encephalopathy in the absence of pre-existing liver disease. The cause of ALF varies across the world. Common causes of ALF in adults include drug toxicity, hepatotropic and non-hepatotropic viruses, herbal and dietary supplements, antituberculosis drugs, and autoimmune hepatitis. The cause of liver failure affects the management and prognosis, and therefore extensive investigation for cause is strongly suggested. Sepsis with multiorgan failure and cerebral oedema remain the leading causes of death in patients with ALF and early identification and appropriate management can alter the course of ALF. Liver transplantation is the best current therapy, although the role of artificial liver support systems, particularly therapeutic plasma exchange, can be useful for patients with ALF, especially in non-transplant centres. In this Seminar, we discuss the cause, prognostic models, and management of ALF.

Acute kidney injury is an unfavorable prognostic factor in acute liver failure and is associated with tumor necrosis factor-alpha

Acute kidney injury (AKI) is a common complication of acute liver failure (ALF); but its pathogenesis is unknown. ALF was divided into 2 subgroups; ALF with hepatic coma, which corresponds to ALF in the US and Europe, and ALF without hepatic coma. AKI has been shown to worsen the prognosis of ALF patients with hepatic coma; however, its prognostic significance in ALF without hepatic coma remains unknown. A single-center retrospective study of 174 patients with ALF was performed. AKI was defined according to KDIGO criteria. AKI developed in 29 (66.0%) of 44 ALF patients with hepatic coma and 27 (38.5%) of 130 ALF patients without hepatic coma. Systemic inflammatory response syndrome (SIRS) was found to be significantly associated with AKI incidence in ALF patients (P < .001). Tumor necrosis factor-alpha (TNF-α) was found to be significantly associated with the presence and severity of AKI (P = .0039 and P = .0140, respectively). On multivariate analysis, TNF-α was an independent risk factor linked with AKI (P = .0103). Even in the absence of hepatic coma, the transplant-free survival rate of ALF was significantly associated with the presence and severity of AKI. Even when hepatic coma is absent, AKI complicated in ALF is strongly associated with TNF-α and worsens the transplant-free survival rate. Before the onset of hepatic coma, plasma exchange, or extracorporeal blood purification to remove inflammatory cytokines should be considered in ALF patients.

Impacts of weaning weights and mycotoxin challenges on jejunal mucosa-associated microbiota, intestinal and systemic health, and growth performance of nursery pigs

Background

This study aimed at investigating the effects of mycotoxin challenge on the growth and physiology of nursery pigs with different weaning weights.

Results

At weaning, 10 pigs were euthanized to collect jejunal mucosa and 90 pigs were assigned following a randomized complete block design in a 2 × 2 factorial arrangement of treatments with 3 pigs per pen. Factors were: weaning weight (light: body weight, BW < 7.5 kg or heavy: BW > 9.0 kg); and dietary mycotoxins (supplementation of 0.2 mg/kg aflatoxins, 2.0 mg/kg deoxynivalenol). All diets had titanium dioxide as an external marker at 0.5%. Growth performance and fecal score were recorded until pigs achieved 20 kg BW (light pigs average BW = 21.1 kg and heavy pigs average BW = 20.5 kg). Pigs were sampled for blood, ileal digesta, jejunal tissue and mucosa at 20 kg BW. Data were analyzed using the mixed procedure of SAS. At weaning, light pigs had decreased (P < 0.05) jejunal interleukin-8, increased (P < 0.05) tumor necrosis factor-α, and increased (P < 0.05) α-diversity indexes of jejunal mucosa-associated microbiota. At 20 kg of BW, light pigs had decreased (P < 0.05) average daily gain (ADG), average daily feed intake (ADFI), and gain to feed ratio (G/F). Mycotoxins decreased (P < 0.05) BW, ADG, ADFI, and G/F. Light pigs tended to have increased fecal score on d 0 (P = 0.080), d 10 (P = 0.069), and increased (P < 0.05) fecal score at 20 kg. Mycotoxins decreased the apparent ileal digestibility of nitrogen (P < 0.05). Light pigs had increased (P < 0.05) intestinal malondialdehydes and interleukin 8. Mycotoxins tended to increase (P = 0.060) intestinal tumor necrosis factor-α.

Conclusions

Nursery pigs with light weaning weight were more susceptible to jejunal inflammation and had impaired intestinal health due to weaning stress, whereas mycotoxins diminished the health and growth of nursery pigs regardless of weaning weight.

Investigation of the Efficacy of a Postbiotic Yeast Cell Wall-Based Blend on Newly-Weaned Pigs under a Dietary Challenge of Multiple Mycotoxins with Emphasis on Deoxynivalenol

Pigs are highly susceptible to mycotoxins. This study investigated the effects of a postbiotic yeast cell wall-based blend (PYCW; Nicholasville, KY, USA) on growth and health of newly-weaned pigs under dietary challenge of multiple mycotoxins. Forty-eight newly-weaned pigs (21 d old) were individually allotted to four dietary treatments, based on a three phase-feeding, in a randomized complete block design (sex; initial BW) with two factors for 36 d. Two factors were dietary mycotoxins (deoxynivalenol: 2000 μg/kg supplemented in three phases; and aflatoxin: 200 μg/kg supplemented only in phase 3) and PYCW (0.2%). Growth performance (weekly), blood serum (d 34), and jejunal mucosa immune and oxidative stress markers (d 36) data were analyzed using MIXED procedure of SAS. Mycotoxins reduced (p < 0.05) average daily feed intake (ADFI) and average daily gain (ADG) during the entire period whereas PYCW did not affect growth performance. Mycotoxins reduced (p < 0.05) serum protein, albumin, creatinine, and alanine aminotransferase whereas PYCW decreased (p < 0.05) serum creatine phosphokinase. Neither mycotoxins nor PYCW affected pro-inflammatory cytokines and oxidative damage markers in the jejunal mucosa. No interaction was observed indicating that PYCW improved hepatic enzymes regardless of mycotoxin challenge. In conclusion, deoxynivalenol (2000 μg/kg, for 7 to 25 kg body weight) and aflatoxin B1 (200 μg/kg, for 16 to 25 kg body weight) impaired growth performance and nutrient digestibility of newly-weaned pigs, whereas PYCW could partially improve health of pigs regardless of mycotoxin challenge.

Takotsubo cardiomyopathy triggered by delirium tremens in a cirrhotic patient with acute-on-chronic liver failure: A case report

A 64-year-old cirrhotic woman was admitted for alcoholic hepatitis associated with renal failure. Subsequently, she displayed symptoms of alcohol withdrawal progressing to delirium tremens. During hospitalization, she developed acute respiratory distress. The electrocardiogram showed diffuse anteroseptal ST elevation. Transthoracic echocardiography revealed systolic left ventricular apical balloon-like dilation, hypokinesis of the left ventricular mid- and apical segments, and a left ventricular ejection fraction of 30%. Coronary angiography was normal and led to the diagnosis of Takotsubo cardiomyopathy. This report describes a singular case of Takotsubo cardiomyopathy precipitated by delirium tremens in a cirrhotic patient with acute-on-chronic liver failure.

Inhibition of jejunal protein synthesis and breakdown in Pseudomonas aeruginosa-induced sepsis pig model

Maintenance of gut integrity has long been recognized as crucial for survival in sepsis, but alterations in protein metabolism have not previously been documented. Therefore, in the present study, we measured in a Pseudomonas aeruginosa-induced porcine sepsis model fractional protein synthesis (FSR) and breakdown rates (FBR) in jejunal mucosa in a fasted, conscious state. FSR was measured by the incorporation rate of stable tracer amino acid (l-[ring-¹³C₆]phenylalanine) into tissue protein. FBR was determined using the relation between blood arterial enrichment and intracellular enrichment of phenylalanine in consecutive mucosal biopsies after a pulse of l-[¹⁵N]phenylalanine. Additionally, we determined the FSR in jejunum, ileum, liver, muscle, and lung tissue. We found in this sham-controlled acute sepsis pig model (control: n = 9; sepsis: n = 13) that jejunal mucosal protein turnover is reduced with both decreased FSR (control: 3.29 ± 0.22; sepsis: 2.32 ± 0.12%/h, P = 0.0008) and FBR (control: 0.72 ± 0.12; sepsis: 0.34 ± 0.04%/h, P = 0.006). We also found that FSR was unchanged in ileum and muscle, whereas it was higher in the liver (control: 0.87 ± 0.05; sepsis: 1.05 ± 0.06%/h, P = 0.041). Our data, obtained with a translational acute sepsis model, suggest that jejunal mucosal protein metabolism is diminished in acute sepsis. Comparison with other tissues indicates that the most serious acute metabolic changes in sepsis occur in the jejunum rather than the muscle. NEW & NOTEWORTHY In a highly translational acute sepsis model, presented data suggest that jejunal mucosal protein metabolism is diminished in acute sepsis, even if the origin of the sepsis is not located in the gut. Comparison with other tissues indicates that the most serious acute changes in the protein synthesis rates in sepsis occur in the gut rather than the muscle. Therefore, we hypothesize that preventing a compromised gut is critical to maintain gut function during sepsis.

Ammonia toxicity: from head to toe?

Ammonia is diffused and transported across all plasma membranes. This entails that hyperammonemia leads to an increase in ammonia in all organs and tissues. It is known that the toxic ramifications of ammonia primarily touch the brain and cause neurological impairment. However, the deleterious effects of ammonia are not specific to the brain, as the direct effect of increased ammonia (change in pH, membrane potential, metabolism) can occur in any type of cell. Therefore, in the setting of chronic liver disease where multi-organ dysfunction is common, the role of ammonia, only as neurotoxin, is challenged. This review provides insights and evidence that increased ammonia can disturb many organ and cell types and hence lead to dysfunction.

Enhanced Lacto-Tri-Peptide Bio-Availability by Co-Ingestion of Macronutrients

Some food-derived peptides possess bioactive properties, and may affect health positively. For example, the C-terminal lacto-tri-peptides Ile-Pro-Pro (IPP), Leu-Pro-Pro (LPP) and Val-Pro-Pro (VPP) (together named here XPP) are described to lower blood pressure. The bioactivity depends on their availability at the site of action. Quantitative trans-organ availability/kinetic measurements will provide more insight in C-terminal tri-peptides behavior in the body. We hypothesize that the composition of the meal will modify their systemic availability. We studied trans-organ XPP fluxes in catheterized pigs (25 kg; n=10) to determine systemic and portal availability, as well as renal and hepatic uptake of a water-based single dose of synthetic XPP and a XPP containing protein matrix (casein hydrolyte, CasH). In a second experiment (n=10), we compared the CasH-containing protein matrix with a CasH-containing meal matrix and the modifying effects of macronutrients in a meal on the availability (high carbohydrates, low quality protein, high fat, and fiber). Portal availability of synthetic XPP was 0.08 ± 0.01% of intake and increased when a protein matrix was present (respectively 3.1, 1.8 and 83 times for IPP, LPP and VPP). Difference between individual XPP was probably due to release from longer peptides. CasH prolonged portal bioavailability with 18 min (absorption half-life, synthetic XPP: 15 ± 2 min, CasH: 33 ± 3 min, p<0.0001) and increased systemic elimination with 20 min (synthetic XPP: 12 ± 2 min; CasH: 32 ± 3 min, p<0.0001). Subsequent renal and hepatic uptake is about 75% of the portal release. A meal containing CasH, increased portal 1.8 and systemic bioavailability 1.2 times. Low protein quality and fiber increased XPP systemic bioavailability further (respectively 1.5 and 1.4 times). We conclude that the amount and quality of the protein, and the presence of fiber in a meal, are the main factors that increase the systemic bioavailability of food-derived XPP.

D-Galactosamine Intoxication in Experimental Animals: Is it Only an Experimental Model of Acute Liver Failure?

BACKGROUND

Short-term administration of Galactosamine to experimental animals causes liver damage and acute liver failure (ALF), as well as acute renal failure in some cases. The aim of our study was to describe kidney disorders that developed in the course of galactosamine-induced liver failure.

MATERIAL AND METHODS

Sprague-Dawley rats were randomly divided into 2 groups: a study group administered galactosamine intraperitoneally and a control group administered saline.

RESULTS

All the animals in the study group developed liver damage and failure within 48 h, with significant increase of alanine (p<0.001), aspartate aminotransferases (p<0.0001), bilirubin (p<0.004), and ammonia (p<0.005) and decrease of albumin (p<0.001) concentrations. Acute renal failure was observed in all test animals, with a significant increase in creatinine (p<0.001) and urea (p<0.001) concentrations and a decrease in creatinine clearance (p<0.0012). Moreover, osmotic clearance (p<0.001), daily natriuresis (p<0.003), and fractional sodium excretion (p<0.016) decreased significantly in this group of animals. The ratio of urine osmolality to serum osmolality did not change. Histopathology of the liver revealed massive necrosis of hepatocytes, whereas renal histopathology showed no changes.

CONCLUSIONS

Acute renal failure that developed in the course of galactosamine-induced ALF was of a functional nature, with the kidneys retaining the ability to concentrate urine and retain sodium, and there were no renal changes in the histopathological examination. It seems that the experimental model of ALF induced by galactosamine can be viewed as a model of hepatorenal syndrome that occurs in the course of acute damage and liver failure.

Effect of nitric oxide pathway regulation on water/sodium balance and renal function in a rodent model of acute liver and renal failure

BACKGROUND

The pathomechanism of acute hepatorenal syndrome (HRS), a particular form of acute renal failure that occurs in the course of acute liver injury, is still poorly understood. The aim of our study was to estimate the influence of the activation and inhibition of the nitric oxide pathway on the water/sodium balance and development of acute renal failure in the course of HRS.

MATERIAL AND METHODS

We used male Sprague-Dawley rats in the acute galactosamine (Ga1N) model of HRS. The nitric oxide synthase (NOS) inhibitors L-NAME and L-arginine were administered intraperitoneally before and after liver damage.

RESULTS

HRS developed in all tested groups. L-NAME increased osmotic clearance and urine volume more effectively before liver injury. Furthermore, administration of L-NAME increased creatinine clearance both before and after Ga1N injection. A double dose of L-NAME did not yield further improvement before Ga1N injection, but improved creatinine clearance after Ga1N intoxication. Injection of L-arginine increased sodium excretion and urine volume, but only after liver injury. Moreover, L-arginine injected after Ga1N caused significant improvement of the creatinine clearance in a dose-dependent manner.

CONCLUSIONS

Our study shows that inhibition of the nitric oxide pathway improves parameters of water and sodium balance and prevents development of acute renal failure in the course of acute liver injury and liver failure. Activation of the nitric oxide system also has a favorable influence on water/sodium balance and renal failure, but only after liver injury.

Acute kidney injury in acute liver failure: a review

Acute liver failure is a rare and often devastating condition consequent on massive liver cell necrosis that frequently affects young, previously healthy individuals resulting in altered cognitive function, coagulopathy and peripheral vasodilation. These patients frequently develop concurrent acute kidney injury (AKI). This abrupt and sustained decline in renal function, through a number of pathogenic mechanisms such as renal hypoperfusion, direct drug-induced nephrotoxicity or sepsis/systemic inflammatory response contributes to increased morbidity and is strongly associated with a worse prognosis. Improved understanding of the pathophysiology AKI in the context of acute liver failure may be beneficial in a number of areas; the development of new and sensitive biomarkers of renal dysfunction, refining prognosis and organ allocation, and ultimately leading to the development of novel treatment strategies, these issues are discussed in more detail in this expert review.

Nitric oxide and L-arginine metabolism in a devascularized porcine model of acute liver failure

In acute liver failure (ALF), the hyperdynamic circulation is believed to be the result of overproduction of nitric oxide (NO) in the splanchnic circulation. However, it has been suggested that arginine concentrations (the substrate for NO) are believed to be decreased, limiting substrate availability for NO production. To characterize the metabolic fate of arginine in early-phase ALF, we systematically assessed its interorgan transport and metabolism and measured the endogenous NO synthase inhibitor asymmetric dimethylarginine (ADMA) in a porcine model of ALF. Female adult pigs (23-30 kg) were randomized to sham (N = 8) or hepatic devascularization ALF (N = 8) procedure for 6 h. We measured plasma arginine, citrulline, ornithine levels; arginase activity, NO, and ADMA. Whole body metabolic rates and interorgan flux measurements were calculated using stable isotope-labeled amino acids. Plasma arginine decreased >85% of the basal level at t = 6 h (P < 0.001), whereas citrulline and ornithine progressively increased in ALF (P < 0.001 and P < 0.001, vs. sham respectively). No difference was found between the groups in the whole body rate of appearance of arginine or NO. However, ALF showed a significant increase in de novo arginine synthesis (P < 0.05). Interorgan data showed citrulline net intestinal production and renal consumption that was related to net renal production of arginine and ornithine. Both plasma arginase activity and plasma ADMA levels significantly increased in ALF (P < 0.001). In this model of early-phase ALF, arginine deficiency or higher ADMA levels do not limit whole body NO production. Arginine deficiency is caused by arginase-related arginine clearance in which arginine production is stimulated de novo.

Strain of experimental animals and modulation of nitric oxide pathway: their influence on development of renal failure in an experimental model of hepatorenal syndrome

INTRODUCTION

Pathomechanism of HRS is still poorly understood. The aim of our study was: (1) to test whether different strains of rats could develop typical HRS, and (2) to estimate the influence of activation and inhibition of nitric oxide for development of renal failure in course of HRS.

MATERIAL AND METHODS

First, we used 16 of Wistar and 16 of Sprague-Dawley rats in galactosamine model of HRS. Next, we used 48 of SDR rats, which received saline, N-nitro-L-arginine or L-arginine before and after liver damage. Twenty four hours urine and blood samples were collected 48 h after saline or Ga1N injection. Biochemical parameters were determined in serum or urine and then creatinine clearance and osmolality clearance were calculated. Liver and kidney tissues were collected for histopathological examination.

RESULTS

Liver failure developed in all tested groups with significant increase of bilirubin (p < 0.001), ALT (p < 0.001) and ammonia (p < 0.001). Nevertheless we did not achieve any evidence of renal failure in Wistar, but we found typical renal failure in Sprague-Dawley group with significant decrease in creatinine clearance (p < 0.0012) and increase in concentration of creatinine and urea (p < 0.001) and (p < 0.001) respectively. Inhibition of NOS prevented development of renal failure with significant improvement of GFR both before (p < 0.0017) and after (p < 0.003) Ga1N injection. Injection of L-arginine after Ga1N injection did not caused significant improvement of GFR.

CONCLUSIONS

Our study showed, that genetic factors might be responsible for development of renal failure in course of HRS and nitric oxide play important role in acute model of this syndrome.

A simple dummy liver assist device prolongs anhepatic survival in a porcine model of total hepatectomy by slight hypothermia

BACKGROUND

Advances in intensive care support such as therapeutic hypothermia or new liver assist devices have been the mainstay of treatment attempting to bridge the gap from acute liver failure to liver transplantation, but the efficacy of the available devices in reducing mortality has been questioned. To address this issue, the present animal study was aimed to analyze the pure clinical effects of a simple extracorporeal dummy device in an anhepatic porcine model of acute liver failure.

METHODS

Total hepatectomy was performed in ten female pigs followed by standardized intensive care support until death. Five animals (dummy group, n = 5) underwent additional cyclic connection to an extracorporeal dummy device which consisted of a plasma separation unit. The separated undetoxified plasma was completely returned to the pigs circulation without any plasma substitution or exchange in contrast to animals receiving intensive care support alone (control group, n = 5). All physiological parameters such as vital and ventilation parameters were monitored electronically; laboratory values and endotoxin levels were measured every 8 hours.

RESULTS

Survival of the dummy device group was 74 ± 6 hours in contrast to 53 ± 5 hours of the control group which was statistically significant (p < 0.05). Body temperature 24 hours after hepatectomy was significantly lower (36.5 ± 0.5°C vs. 38.2 ± 0.7°C) in the dummy device group. Significant lower values were measured for blood lactate (1.9 ± 0.2 vs. 2.5 ± 0.5 mM/L) from 16 hours, creatinine (1.5 ± 0.2 vs. 2.0 ± 0.3 mg/dL) from 40 hours and ammonia (273 ± 122 vs. 1345 ± 700 μg/dL) from 48 hours after hepatectomy until death. A significant rise of endotoxin levels indicated the onset of sepsis at time of death in 60% (3/5) of the dummy device group animals surviving beyond 60 hours from hepatectomy.

CONCLUSIONS

Episodes of slight hypothermia induced by cyclic connection to the extracorporeal dummy device produced a significant survival benefit of more than 20 hours through organ protection and hemodynamic stabilisation. Animal studies which focus on a survival benefit generated by liver assist devices should especially address the aspect of slight transient hypothermia by extracorporeal cooling.

Neuropathological changes in the brain of pigs with acute liver failure

OBJECTIVE

Cerebral edema is a serious complication of acute liver failure (ALF), which may lead to intracranial hypertension and death. An accepted tenet has been that the blood-brain barrier is intact and that brain edema is primarily caused by a cytotoxic etiology due to hyperammonemia. However, the neuropathological changes in ALF have been poorly studied. Using a well characterized porcine model we aimed to investigate ultrastructural changes in the brain from pigs suffering from ALF.

MATERIALS AND METHODS

Sixteen female Norwegian Landrace pigs weighing 27-35 kg were randomised into two groups: ALF (n = 8) and sham operated controls (n = 8). ALF was induced with an end-to-side portacaval shunt followed by ligation of the hepatic arteries. Biopsies were harvested from three different areas of the brain (frontal lobe, cerebellum, and brain stem) following eight hours of ALF and analyzed using electron microscopy.

RESULTS

Profound perivascular and interstitial edema were found in all three areas. Disruption of pericytic and astrocytic processes were seen, reflecting breakdown/lesion of the blood-brain barrier in animals suffering from ALF. Furthermore, neurons and axons were edematous and surrounded by vesicles. Severe damage to Purkinje neuron (necrosis) and damaged myelin were seen in the cerebellum and brain stem, respectively. Biopsies from sham operated animals were normal.

CONCLUSIONS

Our data support the concept that vasogenic brain edema plays an important role in the development of intracranial hypertension in pigs with ALF.

L-ornithine and phenylacetate synergistically produce sustained reduction in ammonia and brain water in cirrhotic rats

Treatment of hyperammonemia and hepatic encephalopathy in cirrhosis is an unmet clinical need. The aims of this study were to determine whether L-ornithine and phenylacetate/phenylbutyrate (administered as the pro-drug phenylbutyrate) (OP) combined are synergistic and produce sustained reduction in ammonia by L-ornithine acting as a substrate for glutamine synthesis, thereby detoxifying ammonia, and the phenylacetate excreting the ornithine-derived glutamine as phenylacetylglutamine in the urine. Sprague-Dawley rats were studied 4 weeks after bile duct ligation (BDL) or sham operation. Study 1: Three hours before termination, an internal carotid sampling catheter was inserted, and intraperitoneal saline (placebo), OP, phenylbutyrate, or L-ornithine were administered after randomization. BDL was associated with significantly higher arterial ammonia and brain water and lower brain myoinositol (P < 0.01, respectively), compared with sham-operated controls, which was significantly improved in the OP-treated animals; arterial ammonia (P < 0.001), brain water (P < 0.05), brain myoinositol (P < 0.001), and urinary phenylacetylglutamine (P < 0.01). Individually, L-ornithine or phenylbutyrate were similar to the BDL group. In study 2, BDL rats were randomized to saline or OP administered intraperitoneally for 6 hours or 3, 5, or 10 days and were sacrificed between 4.5 and 5 weeks. The results showed that the administration of OP was associated with sustained reduction in arterial ammonia (P < 0.01) and brain water (P < 0.01) and markedly increased arterial glutamine (P < 0.01) and urinary excretion of phenylacetylglutamine (P < 0.01) in each of the OP treated groups.

CONCLUSION

The results of this study provide proof of the concept that L-ornithine and phenylbutyrate/phenylacetate act synergistically to produce sustained improvement in arterial ammonia, its brain metabolism, and brain water in cirrhotic rats.

L-ornithine phenylacetate attenuates increased arterial and extracellular brain ammonia and prevents intracranial hypertension in pigs with acute liver failure

Hyperammonemia is a feature of acute liver failure (ALF), which is associated with increased intracranial pressure (ICP) and brain herniation. We hypothesized that a combination of L-ornithine and phenylacetate (OP) would synergistically reduce toxic levels of ammonia by (1) L-ornithine increasing glutamine production (ammonia removal) through muscle glutamine synthetase and (2) phenylacetate conjugating with the ornithine-derived glutamine to form phenylacetylglutamine, which is excreted into the urine. The aims of this study were to determine the effect of OP on arterial and extracellular brain ammonia concentrations as well as ICP in pigs with ALF (induced by liver devascularization). ALF pigs were treated with OP (L-ornithine 0.07 g/kg/hour intravenously; phenylbutyrate, prodrug for phenylacetate; 0.05 g/kg/hour intraduodenally) for 8 hours following ALF induction. ICP was monitored throughout, and arterial and extracellular brain ammonia were measured along with phenylacetylglutamine in the urine. Compared with ALF + saline pigs, treatment with OP significantly attenuated concentrations of arterial ammonia (589.6 +/- 56.7 versus 365.2 +/- 60.4 mumol/L [mean +/- SEM], P= 0.002) and extracellular brain ammonia (P= 0.01). The ALF-induced increase in ICP was prevented in ALF + OP-treated pigs (18.3 +/- 1.3 mmHg in ALF + saline versus 10.3 +/- 1.1 mmHg in ALF + OP-treated pigs;P= 0.001). The value of ICP significantly correlated with the concentration of extracellular brain ammonia (r(2) = 0.36,P< 0.001). Urine phenylacetylglutamine levels increased to 4.9 +/- 0.6 micromol/L in ALF + OP-treated pigs versus 0.5 +/- 0.04 micromol/L in ALF + saline-treated pigs (P< 0.001).

CONCLUSION

L-Ornithine and phenylacetate act synergistically to successfully attenuate increases in arterial ammonia, which is accompanied by a significant decrease in extracellular brain ammonia and prevention of intracranial hypertension in pigs with ALF.

Erythropoietin during porcine aortic balloon occlusion-induced ischemia/reperfusion injury

BACKGROUND

Aortic occlusion causes ischemia/reperfusion injury, kidney and spinal cord being the most vulnerable organs. Erythropoietin improved ischemia/reperfusion injury in rodents, which, however, better tolerate ischemia/reperfusion than larger species. Therefore, we investigated whether erythropoietin attenuates porcine aortic occlusion ischemia/reperfusion injury.

MATERIALS AND METHODS

Before occluding the aorta for 45 mins by inflating intravascular balloons, we randomly infused either erythropoietin (n = 8; 300 IU/kg each over 30 mins before and during the first 4 hrs of reperfusion) or vehicle (n = 6). During aortic occlusion, mean arterial pressure was maintained at 80% to 120% of baseline by esmolol, nitroglycerine, and adenosine 5'-triphosphate. During reperfusion, noradrenaline was titrated to keep mean arterial pressure >80% of baseline. Kidney perfusion and function were assessed by fractional Na-excretion, p-aminohippuric acid and creatinine clearance, spinal cord function by lower extremity reflexes and motor evoked potentials. Blood isoprostane levels as well as blood and tissue catalase and superoxide dismutase activities allowed evaluation of oxidative stress. After 8 hrs of reperfusion, kidney and spinal cord specimens were taken for histology (hematoxylin-eosin, Nissl staining) and immunohistochemistry (TUNEL assay for apoptosis).

RESULTS

Parameters of oxidative stress and antioxidative activity were comparable. Erythropoietin reduced the noradrenaline requirements to achieve the hemodynamic targets and may improve kidney function despite similar organ blood flow, histology, and TUNEL staining. Neuronal damage and apoptosis was attenuated in the thoracic spinal cord segments without improvement of its function.

CONCLUSION

During porcine aortic occlusion-induced ischemia/reperfusion erythropoietin improved kidney function and spinal cord integrity. The lacking effect on spinal cord function was most likely the result of the pronounced neuronal damage associated with the longlasting ischemia.

Type I inositol 1, 4, 5-triphosphate receptors increase in kidney of mice with fulminant hepatic failure

AIM: To delineate the mechanisms of renal vasocon-striction in hepatorenal syndrome (HRS), we investigated the expression of typeIinositol 1, 4, 5-triphosphate receptors (IP₃RI) of kidney in mice with fulminant hepatic failure (FHF).

METHODS: FHF was induced by lipopolysaccharide (LPS) in D-galactosamine (GalN) sensitized BALB/c mice. There were 20 mice in normal saline (NS)-treated group, 20 mice in LPS-treated group, 20 mice in GalN-treated group, and 60 mice in GalN/LPS-treated group (FHF group). Liver and kidney tissues were obtained at 2, 6, and 9 h after administration. The liver and kidney specimens were stained with hematoxylin-eosin for studying morphological changes under light microscope. The expression of IP₃RIin kidney tissue was tested by immunohistochemistry, Western blot and reverse transcription (RT)-PCR.

RESULTS: Kidney tissues were morphologically normal at all time points in all groups. IP₃RIproteins were found localized in the plasma region of glomerular mesangial cells (GMC) and vascular smooth muscle cells (VSMC) in kidney by immunohistochemical staining. In kidney of mice with FHF at 6 h and 9 h IP₃RIstaining was up-regulated. Results from Western blot demonstrated consistent and significant increment of IP₃RIexpression in mice with FHF at 6 h and 9 h (t = 3.16, P < 0.05; t = 5.43, P < 0.01). Furthermore, we evaluated IP₃RImRNA expression by RT-PCR and observed marked up-regulation of IP₃RImRNA in FHF samples at 2 h, 6 h and 9 h compared to controls (t = 2.97, P < 0.05; t = 4.42, P < 0.01; t = 3.81, P < 0.01).

CONCLUSION: The expression of IP₃RIprotein increased in GMC and renal VSMC of mice with FHF, possibly caused by up-regulation of IP₃RImRNA.