Jeanne Gottstein

Screening for Wilson Disease in Acute Liver Failure: A Comparison of Currently Available Diagnostic Tests

Acute liver failure (ALF) due to Wilson disease (WD) is invariably fatal without emergency liver transplantation. Therefore, rapid diagnosis of WD should aid prompt transplant listing. To identify the best method for diagnosis of ALF due to WD (ALF‐WD), data and serum were collected from 140 ALF patients (16 with WD), 29 with other chronic liver diseases and 17 with treated chronic WD. Ceruloplasmin (Cp) was measured by both oxidase activity and nephelometry and serum copper levels by atomic absorption spectroscopy. In patients with ALF, a serum Cp <20 mg/dL by the oxidase method provided a diagnostic sensitivity of 21% and specificity of 84% while, by nephelometry, a sensitivity of 56% and specificity of 63%. Serum copper levels exceeded 200 μg/dL in all ALF‐WD patients measured (13/16), but were also elevated in non‐WD ALF. An alkaline phosphatase (AP) to total bilirubin (TB) ratio <4 yielded a sensitivity of 94%, specificity of 96%, and a likelihood ratio of 23 for diagnosing fulminant WD. In addition, an AST:ALT ratio >2.2 yielded a sensitivity of 94%, a specificity of 86%, and a likelihood ratio of 7 for diagnosing fulminant WD. Combining the tests provided a diagnostic sensitivity and specificity of 100%. Conclusion: Conventional WD testing utilizing serum ceruloplasmin and/or serum copper levels are less sensitive and specific in identifying patients with ALF‐WD than other available tests. More readily available laboratory tests including alkaline phosphatase, bilirubin and serum aminotransferases by contrast provides the most rapid and accurate method for diagnosis of ALF due to WD. (HEPATOLOGY 2008.)

Mild hypothermia modifies ammonia-induced brain edema in rats after portacaval anastomosis.

BACKGROUND & AIMS The pathogenesis of brain edema in fulminant hepatic failure is still unresolved. Mild hypothermia (33 degrees-35 degreesC) can ameliorate brain edema after traumatic brain injury. We evaluated mild hypothermia in a model of ammonia-induced brain edema in which accumulation of brain glutamine has been proposed as a key pathogenic factor. METHODS After portacaval anastomosis, anesthetized rats were infused with ammonium acetate at 33 degrees, 35 degrees, and 37 degreesC or vehicle at 37 degreesC. Water and glutamine levels in the brain, cardiac output, and regional and cerebral hemodynamics were measured when intracranial pressure increased 3-4-fold (ammonia infusion at 37 degrees) and matched times (other groups). RESULTS Mild hypothermia reduced ammonia-induced brain swelling and increased intracranial pressure. Brain glutamine level was not decreased by hypothermia. Brain edema was accompanied by a specific increase in cerebral blood flow and oxygen consumption, which were normal in both hypothermic groups. When the ammonia infusion was continued in hypothermic rats, plasma ammonia levels continued to increase and brain swelling eventually developed. CONCLUSIONS Mild hypothermia delays ammonia-induced brain edema. In this model, an increase in cerebral perfusion is required for brain edema to become manifest. Mild hypothermia could be tested for treatment of intracranial hypertension in fulminant hepatic failure.

Chronic hyponatremia exacerbates ammonia-induced brain edema in rats after portacaval anastomosis

BACKGROUND/AIM Abnormalities in brain organic osmolytes are associated with hepatic encephalopathy and with chronic hyponatremia. In spite of the high frequency of hyponatremia in acute and chronic hepatic failure, its role in the development of neurological complications in liver disease is poorly understood. We aimed to study the effect of prior hyponatremia on the development of ammonia-induced brain edema in rats after portacaval anastomosis. In this model, brain swelling is mediated in part through an increase in brain glutamine, an organic osmolyte. METHODS Hyponatremia was induced in rats with 1-desamino-8-D-arginine vasopressin (DDAVP) administered through an osmotic minipump for 1 week. This was followed by performance of a portacaval anastomosis and ammonia infusion. At the end of the infusion, brain water (density gradient) and key brain organic osmolytes (HPLC) were measured. RESULTS Rats with hyponatremia showed a decrease in all three brain organic osmolytes measured: glutamine, myo-inositol and taurine. Hyperammonemia resulted in the expected rise in glutamine, with a reduction of myo-inositol and taurine. In the combined group (hyponatremia plus hyperammonemia), the rise in brain glutamine induced by ammonia infusion was attenuated (10.6+/-0.9 mM/kg vs. 15.5+/-0.8 mM/kg hyperammonemia alone; p<0.05). In spite of this limited rise in brain glutamine, ammonia infusion to hyponatremic rats exacerbated brain swelling (82.3+/-0.3% vs. 80.6+/-0.1%; p<0.05). CONCLUSIONS Hyponatremia worsens brain swelling in a model of ammonia-induced brain edema. The decrease in the concentration of brain organic osmolytes induced by hyponatremia does not protect the brain from the development of ammonia-induced brain edema.

Impact of preoperative overt hepatic encephalopathy on neurocognitive function after liver transplantation

In the current Model for End‐Stage Liver Disease allocation system, patients are at risk of suffering repeated episodes of hepatic encephalopathy (HE) while waiting for an orthotopic liver transplantation (OLT); the posttransplantation impact of these episodes has not been well explored. We evaluated the cognitive function and quality of life in a group of OLT recipients (n = 25) who had suffered from overt HE prior to their procedure (HE‐PreLT group) and compared their performance to that of a similar group of patients (n = 14) without overt HE (No HE‐PreLT group) as well as to controls. Patients were selected from a cohort of 280 patients who underwent OLT during this period; the presence of clinical confounders excluded many of the remaining subjects. Demographic and clinical characteristics were balanced among groups. At an average of 18 months after OLT, we administered 2 neuropsychological batteries [Psychometric Hepatic Encephalopathy Score (PHES) test battery and Repeatable Battery for the Assessment of Neuropsychological Status (RBANS)]; a pyschophysiological test (critical flicker frequency); and the SF‐36 quality of life score. The HE‐PreLT group scored below controls in 5 of 6 cognitive domains tested by RBANS, 3 of 6 PHES subtests, as well as the critical flicker frequency test. The No HE‐PreLT group scored below the controls in 1 of the 6 cognitive domains tested by RBANS. The more severe neurocognitive abnormalities seen in the HE‐PreLT group did not appear to affect quality of life, as lower values than normative data were only found in 1 of the 8 SF‐36 scales. In conclusion, neurocognitive abnormalities were more severe in liver transplant recipients that had suffered from overt HE prior to OLT. Prospective studies of neurocognitive function pre‐OLT and post‐OLT are needed to fully determine the impact of such abnormalities. Liver Transpl 15:184–192, 2009.

Portal-Systemic Shunting and the Hemodynamic Effects of Nitroglycerin in the Rat

A hemodynamic response to oral nitroglycerin has been used recently to estimate the extent of portal systemic shunts in humans. We studied the hemodynamic effects of this drug in the rat with partial portal vein ligation, a model in which portal hypertension develops and the extent of portal-systemic collaterals can be measured. Two to ten days after the initial procedure, shunted and sham-operated controls received a continuous infusion of nitroglycerin into a jugular vein, the ileocolic vein, or intrajejunally. The response of systolic arterial pressure to intravenous nitroglycerin was similar in shunted and sham animals. The cumulative dose-response curve showed an earlier and more pronounced response in shunted rats receiving nitroglycerin intraportally, suggesting a marked increase in bioavailability. When the arterial response to nitroglycerin, infused intraportally at 1 microgram/kg X min, was compared to the extent of ileocolic shunting, measured with radioactive microspheres, a close correlation (r = 0.84) was seen; shunting values ranged from 0% (sham) to 97%. Additionally, in shunted rats a more pronounced response to intraportal, compared to intrajejunal, infusion suggested a contribution of the intestine to the first-pass elimination of the drug. The bioavailability of intraportal and intrajejunal nitroglycerin is influenced by the extent of portal systemic collaterals. A significant reduction in portal vein pressure in response to nitroglycerin seen in this animal model supports its testing as a therapeutic agent in portal hypertension.

Dysregulation of the unfolded protein response in db/db mice with diet-induced steatohepatitis†

In humans with nonalcoholic fatty liver, diabetes is associated with more advanced disease. We have previously shown that diabetic db/db mice are highly susceptible to methionine choline‐deficient diet (MCD)‐induced hepatic injury. Because activation of the unfolded protein response (UPR) is an important adaptive cellular mechanism in diabetes, obesity, and fatty liver, we hypothesized that dysregulation of the UPR may partially explain how diabetes could promote liver injury. Db/db and db/m mice were fed the MCD or control diet for 4 weeks to characterize differences in UPR activation and downstream injury. Wildtype mice (C57BLKS/J) fed the MCD or control diet were treated with SP600125; a c‐Jun N‐terminal kinase (JNK) inhibitor and its effect on liver injury and UPR activation was measured. The MCD diet resulted in global up‐regulation of the UPR in both diabetic db/db and nondiabetic db/m mice. db/db mice had an inadequate activation of recovery pathways (GADD34, XBP‐1(s)) and accentuated activation of injury pathways related to persistent eif2‐α phosphorylation (activating transcription factor 4 [ATF‐4], C/EBP homologous transcription factor [CHOP], oxireductase endoplasmic reticulum oxidoreductin‐1 [ERO‐1α], JNK, nuclear factor kappaB [NF‐κB]) compared to db/m mice. This led to increased expression of inflammatory mediators such as tumor necrosis factor alpha (TNF‐α), ICAM‐1, and MCP‐1 compared to db/m mice. Interestingly, whereas pharmacologic JNK inhibition did not prevent the development of MCD diet‐induced steatohepatitis, it did attenuate UPR and downstream inflammatory signaling. Conclusion: MCD‐fed db/db mice develop a more proinflammatory milieu than db/m mice associated with an impaired ability to dephosphorylate eif2‐α through GADD34, impairing cellular recovery. These data may enhance our understanding of why diabetics with nonalcoholic steatohepatitis are prone to develop more severe liver injury than nondiabetic patients. (HEPATOLOGY 2011;)

Elevated troponin I levels in acute liver failure: Is myocardial injury an integral part of acute liver failure?

Although rare instances of cardiac injury or arrhythmias have been reported in acute liver failure (ALF), overall, the heart is considered to be spared in this condition. Troponin I, a sensitive and specific marker of myocardial injury, may be elevated in patients with sepsis and acute stroke without underlying acute coronary syndrome, indicating unrecognized cardiac injury in these settings. We sought to determine whether subclinical cardiac injury might also occur in acute liver failure. Serum troponin I levels were measured in 187 patients enrolled in the US Acute Liver Failure Study Group registry, and correlated with clinical variables and outcomes. Diagnoses were representative of the larger group of >1000 patients thus far enrolled and included 80 with acetaminophen‐related injury, 26 with viral hepatitis, 19 with ischemic injury, and 62 others. Overall, 74% of patients had elevated troponin I levels (>0.1 ng/ml). Patients with elevated troponin I levels were more likely to have advanced hepatic coma (grades III or IV) or to die (for troponin I levels >0.1 ng/ml, odds ratio 3.88 and 4.69 for advanced coma or death, respectively). Conclusion: In acute liver failure, subclinical myocardial injury appears to occur more commonly than has been recognized, and its pathogenesis in the context of acute liver failure is unclear. Elevated troponin levels are associated with a significant increase in morbidity and mortality. Measurement of troponin I levels may be helpful in patients with acute liver failure, to detect unrecognized myocardial damage and as a marker of unfavorable outcome. (HEPATOLOGY 2007;45:1489–1495.)

Predictive value of actin‐free Gc‐globulin in acute liver failure

Serum concentrations of the actin scavenger Gc‐globulin may provide prognostic information in acute liver failure (ALF). The fraction of Gc‐globulin not bound to actin is postulated to represent a better marker than total Gc‐globulin but has been difficult to measure. We tested a new rapid assay for actin‐free Gc‐globulin to determine its prognostic value when compared with the Kings College Hospital (KCH) criteria in a large number of patients with ALF. A total of 252 patients with varying etiologies from the U.S. ALF Study Group registry were included; the first 178 patients constituted the learning set, and the last 74 patients served as the validation set. Actin‐free Gc‐globulin was determined with a commercial enzyme‐linked immunosorbent assay kit. The median (range) actin‐free Gc‐globulin level at admission for the learning set was significantly reduced compared with controls (47 [0‐183] mg/L vs. 204 [101‐365] mg/L, respectively, P < 0.001). Gc‐globulin levels were significantly higher in spontaneous survivors than in patients who died or were transplanted (53 [0‐129] mg/L vs. 37 [0‐183] mg/L, P = 0.002). A receiver operating characteristic curve analysis showed that a 40 mg/L cutoff level carried the best prognostic information, yielding positive and negative predictive values of 68% and 67%, respectively, in the validation set. The corresponding figures for the KCH criteria were 72% and 64%. A new enzyme‐linked immunosorbent assay for actin‐free Gc‐globulin provides the same (but not optimal) prognostic information as KCH criteria in a single measurement at admission. Liver Transpl 13:1324–1329, 2007.

Brain edema and intracranial hypertension in rats after total hepatectomy

BACKGROUND/AIMS Glutamine, generated from ammonia in astrocytes, may account for brain edema in acute liver failure. Recent studies showing decreased intracranial pressure after hepatectomy in humans suggest that factors released by the necrotic liver could play a pathogenic role in brain swelling. The aim of this study was to examine whether brain edema and intracranial hypertension develop in hepatectomized rats. METHODS Rats underwent a portacaval anastomosis or a sham operation. At 24 hours, animals underwent a second sham operation or a total hepatectomy. Intracranial pressure was continuously monitored, and cortical water and glutamine contents were measured after the rats were killed. In a second experiment, hepatectomized and devascularized (portacaval anastomosis plus hepatic artery ligation) rats were killed every 2 hours and at the time of intracranial hypertension. RESULTS Although brain edema developed in both groups with liver failure, devascularization resulted in a higher brain water content in spite of an equivalent increase in glutamine concentration. Intracranial pressure increased to a similar degree in both groups, but all parameters increased earlier in anhepatic rats. CONCLUSIONS Hepatectomized rats develop brain edema and intracranial hypertension. The temporal sequence in this model supports the role of glutamine as an organic osmolyte. In addition, other factors (e.g., brain volume) may contribute to intracranial hypertension in hepatectomized rats.

Vasopressin accelerates experimental ammonia-induced brain edema in rats after portacaval anastomosis

BACKGROUND/AIMS Cerebral hyperemia is an important contributor to the development of brain edema in fulminant hepatic failure. Rats receiving an ammonia infusion after portacaval anastomosis (PCA) demonstrate a rise in cerebral blood flow (CBF) with brain edema at 180 min. Vasopressin (VP), a systemic vasoconstrictor which in the rat dilates cerebral vessels through V(2) receptors, was used to ascertain the effects of increasing CBF. METHODS Changes in CBF were measured with Laser Doppler flowmetry (LDF). Absolute CBF was measured with radioactive microspheres to calculate oxygen and ammonia uptake. RESULTS Compared to the NH(3)+Vehicle group, VP+NH(3) infusion accelerated the rise in CBF (117+/-21 vs. -6+/-12%, P<0.01), and the development of brain edema (81.09+/-0.17 vs. 80.29+/-0.06%, P<0.01). Radioactive microspheres confirmed these results (254+/-44 vs. 106+/-9.5 ml/min/100 g, P<0.01). Oxygen uptake was similar. Ammonia uptake was more than twofold higher in the VP+NH(3) group. A V(1) antagonist negated the higher mean arterial pressure (MAP) that occurs with VP but cerebral hyperemia still occurred. A V(2) antagonist resulted in similar systemic pressures, CBF and brain water compared to the VP+NH(3) group. CONCLUSIONS In this model, an increase in CBF with VP hastens the development of brain edema while increasing ammonia delivery to the brain.