Failure of insulin and glucagon infusion to stimulate liver regeneration in fulminant hepatic failure

Intravenous N-acetylcysteine improves transplant-free survival in early stage non-acetaminophen acute liver failure

BACKGROUND & AIMS

N-acetylcysteine (NAC), an antidote for acetaminophen poisoning, might benefit patients with non-acetaminophen-related acute liver failure.

METHODS

In a prospective, double-blind trial, acute liver failure patients without clinical or historical evidence of acetaminophen overdose were stratified by site and coma grade and assigned randomly to groups that were given NAC or placebo (dextrose) infusion for 72 hours. The primary outcome was overall survival at 3 weeks. Secondary outcomes included transplant-free survival and rate of transplantation.

RESULTS

A total of 173 patients received NAC (n = 81) or placebo (n = 92). Overall survival at 3 weeks was 70% for patients given NAC and 66% for patients given placebo (1-sided P = .283). Transplant-free survival was significantly better for NAC patients (40%) than for those given placebo (27%; 1-sided P = .043). The benefits of transplant-free survival were confined to the 114 patients with coma grades I-II who received NAC (52% compared with 30% for placebo; 1-sided P = .010); transplant-free survival for the 59 patients with coma grades III-IV was 9% in those given NAC and 22% in those given placebo (1-sided P = .912). The transplantation rate was lower in the NAC group but was not significantly different between groups (32% vs 45%; P = .093). Intravenous NAC generally was well tolerated; only nausea and vomiting occurred significantly more frequently in the NAC group (14% vs 4%; P = .031).

CONCLUSIONS

Intravenous NAC improves transplant-free survival in patients with early stage non-acetaminophen-related acute liver failure. Patients with advanced coma grades do not benefit from NAC and typically require emergency liver transplantation.

[Fulminant and subfulminant hepatitis: causes and treatment]

Fulminant hepatitis is an emergency because within a few hours, the physician must find the cause of the hepatitis (not identified in 15 to 20% of cases), rule out any contraindication to liver transplantation, verify that it is indicated, and prevent and/or treat the complications associated with liver failure. Viruses (especially hepatitis viruses A and B), drugs, and toxic agents are the most common causes of fulminant hepatitis, with the proportions varying between countries. Hepatitis viruses, the leading cause through 1995-1996, have fallen behind drugs and in particular paracetamol, which is now the leading cause of this disease in Europe and in the United States. There are also other rarer causes: other viruses (e.g., herpes virus HSV1 or 2, hepatitis virus E, parvovirus B19, and chickenpox-herpes zoster), Wilson Disease, acute Budd-Chiari and Reyes syndromes, autoimmune hepatitis, neoplastic infiltration of the liver, hypoxic hepatitis, heatstroke, acute pregnancy-related steatosis, and the HELLP syndrome. Prognosis is essentially determined by neurological status, but is also affected very rapidly by damage to other organs. Liver transplantation has revolutionized the prognosis of fulminant hepatitis, causing survival to increase from 10-20% (all causes combined) to 75-80% at 1 year and 70% at 5 years. These patients can be treated only in specialized centers with access to liver transplantation and to different modern means of liver resuscitation (hypothermia, artificial liver support, albumin dialysis, monitoring intracranial pressure and cerebral perfusion, etc.) -all from the onset of the disease.

Acute liver failure: Summary of a workshop

Acute liver failure (ALF) is a rare but challenging clinical syndrome with multiple causes; a specific etiology cannot be identified in 15% of adult and 50% of pediatric cases. The course of ALF is variable and the mortality rate is high. Liver transplantation is the only therapy of proven benefit, but the rapidity of progression and the variable course of ALF limit its use. Currently in the United States, spontaneous survival occurs in approximately 45%, liver transplantation in 25%, and death without transplantation in 30% of adults with ALF. Higher rates of spontaneous recovery (56%) and transplantation (31%) with lower rates of death (13%) occur in children. The outcome of ALF varies by etiology, favorable prognoses being found with acetaminophen overdose, hepatitis A, and ischemia (approximately 60% spontaneous survival), and poor prognoses with drug-induced ALF, hepatitis B, and indeterminate cases (approximately 25% spontaneous survival). Excellent intensive care is critical in management of patients with ALF. Nonspecific therapies are of unproven benefit. Future possible therapeutic approaches include N-acetylcysteine, hypothermia, liver assist devices, and hepatocyte transplantation. Advances in stem cell research may allow provision of cells for bioartificial liver support. ALF presents many challenging opportunities in both clinical and basic research.

Mechanisms and outcomes of drug- and toxicant-induced liver toxicity in diabetes

Increase dincidences of hepatotoxicity have been observed in diabetic patients receiving drug therapies. Neither the mechanisms nor the predisposing factors underlying hepatotoxicity in diabetics are clearly understood. Animal studies designed to examine the mechanisms of diabetes-modulated hepatotoxicity have traditionally focused only on bioactivation/detoxification of drugs and toxicants. It is becoming clear that once injury is initiated, additional events determine the final outcome of liver injury. Foremost among them are two leading mechanisms: first, biochemical mechanisms that lead to progression or regression of injury; and second, whether or not timely and adequate liver tissue repair occurs to mitigate injury and restore liver function. The liver has a remarkable ability to repair and restore its structure and function after physical or chemical-induced damage. The dynamic interaction between biotransformation-based liver injury and compensatory tissue repair plays a pivotal role in determining the ultimate outcome of hepatotoxicity initiated by drugs or toxicants. In this review, mechanisms underlying altered hepatotoxicity in diabetes with emphasis on both altered bioactivation and liver tissue repair are discussed. Animal models of both marked sensitivity (diabetic rats) and equally marked protection (diabetic mice) from drug-induced hepatotoxicity are described. These examples represent a remarkable species difference. Availability of the rodent diabetic models offers a unique opportunity to uncover mechanisms of clinical interest in averting human diabetic sensitivity to drug-induced hepatotoxicities. While the rat diabetic models appear to be suitable, the diabetic mouse models might not be suitable in preclinical testing for potential hepatotoxic effects of drugs or toxicants, because regardless of type 1 or type2 diabetes, mice are resistant to acute drug-or toxicant-induced toxicities.

During thioacetamide-induced acute liver failure, the proliferative response of hepatocytes to thyroid hormone is maintained, indicating a potential therapeutic approach to toxin-induced liver disease

In toxic liver injury, proliferation of preexisting hepatocytes helps restore liver mass and function. While loss of liver mass per se stimulates hepatocyte proliferation, exogenous mitogens have a potential role in enhancing liver regeneration. The aim of this study was to characterize the effects of the mitogen, tri-iodothyonine, on the regenerative capacity of hepatocytes during thioacetamide-induced liver failure. Rats received (two) thioacetamide injections and, 12 hr later, either tri-iodothyonine or vehicle-only control. Liver cell proliferation was assessed and comparison made with other control groups receiving tri-iodothyonine or vehicle only. In rats with thioacetamide-induced hepatitis the proportion of hepatocytes in S-phase was greater in the tri-iodothyonine group (27+/-3.5%) compared to the vehicle-only group (20+/-2.5%; P < 0.05), with, notably, a greater number of midzonal (BrdU) positive hepatocytes in the tri-iodothyonine group. We conclude that the ability of hepatocytes in the midzonal areas of rat liver to proliferate in response to tri-iodothyonine is maintained during severe acute toxic injury.

Type 2 diabetic rats are sensitive to thioacetamide hepatotoxicity

Previously, we reported high hepatotoxic sensitivity of type 2 diabetic (DB) rats to three dissimilar hepatotoxicants. Additional work revealed that a normally nonlethal dose of CCl4 was lethal in DB rats due to inhibited compensatory tissue repair. The present study was conducted to investigate the importance of compensatory tissue repair in determining the final outcome of hepatotoxicity in diabetes, using another structurally and mechanistically dissimilar hepatotoxicant, thioacetamide (TA), to initiate liver injury. A normally nonlethal dose of TA (300 mg/kg, ip), caused 100% mortality in DB rats. Time course studies (0 to 96 h) showed that in the non-DB rats, liver injury initiated by TA as assessed by plasma alanine or aspartate aminotransferase and hepatic necrosis progressed up to 48 h and regressed to normal at 96 h resulting in 100% survival. In the DB rats, liver injury rapidly progressed resulting in progressively deteriorating liver due to rapidly expanding injury, hepatic failure, and 100% mortality between 24 and 48 h post-TA treatment. Covalent binding of 14C-TA-derived radiolabel to liver tissue did not differ from that observed in the non-DB rats, indicating similar bioactivation-based initiation of hepatotoxicity. S-phase DNA synthesis measured by [3H]-thymidine incorporation, and advancement of cells through the cell division cycle measured by PCNA immunohistochemistry, were substantially inhibited in the DB rats compared to the non-DB rats challenged with TA. Thus, inhibited cell division and compromised tissue repair in the DB rats resulted in progressive expansion of liver injury culminating in mortality. In conclusion, it appears that similar to type 1 diabetes, type 2 diabetes also increases sensitivity to dissimilar hepatotoxicants due to inhibited compensatory tissue repair, suggesting that sensitivity to hepatotoxicity in diabetes occurs in the absence as well as presence of insulin.

The role of NF-kappaB signaling in impaired liver tissue repair in thioacetamide-treated type 1 diabetic rats

Previously we reported that an ordinarily nonlethal dose of thioacetamide (300 mg/kg) causes liver failure and 90% mortality in type 1 diabetic rats, primarily because of inhibited tissue repair. On the other hand, the diabetic rats receiving 30 mg thioacetamide/kg exhibited equal initial liver injury and delayed tissue repair compared to nondiabetic rats receiving 300 mg thioacetamide/kg, resulting in a delay in recovery from that liver injury and survival. These data indicate that impaired tissue repair in diabetes is a dose-dependent function of diabetes. The objective of the present study was to test the hypothesis that disrupted nuclear factor-kappaB (NF-kappaB)-regulated cyclin D1 signaling may explain dose-dependent impaired tissue repair in the thioacetamide-treated diabetic rats. Administration of 300 mg thioacetamide/kg to nondiabetic rats led to sustained NF-kappaB-regulated cyclin D1 signaling, explaining prompt compensatory tissue repair and survival. For the first time, we report that NF-kappaB-DNA binding is dependent on the dose of thioacetamide in the liver tissue of the diabetic rats. Administration of 300 mg thioacetamide/kg to diabetic rats inhibited NF-kappaB-regulated cyclin D1 signaling, explaining inhibited tissue repair, liver failure and death, whereas remarkably higher NF-kappaB-DNA binding but transient down regulation of cyclin D1 expression explains delayed tissue repair in the diabetic rats receiving 30 mg thioacetamide/kg. These data suggest that dose-dependent NF-kappaB-regulated cyclin D1 signaling explains inhibited versus delayed tissue repair observed in the diabetic rats receiving 300 and 30 mg thioacetamide/kg, respectively.

Treatment of amatoxin poisoning: 20-year retrospective analysis

BACKGROUND

Amatoxin poisoning is a medical emergency characterized by a long incubation time lag, gastrointestinal and hepatotoxic phases, coma, and death. This mushroom intoxication is ascribed to 35 amatoxin-containing species belonging to three genera: Amanita, Galerina, and Lepiota. The major amatoxins, the alpha-, beta-, and gamma-amanitins, are bicyclic octapeptide derivatives that damage the liver and kidney via irreversible binding to RNA polymerase II.

METHODS

The mycology and clinical syndrome of amatoxin poisoning are reviewed. Clinical data from 2108 hospitalized amatoxin poisoning exposures as reported in the medical literature from North America and Europe over the last 20 years were compiled. Preliminary medical care, supportive measures, specific treatments used singly or in combination, and liver transplantation were characterized. Specific treatments consisted of detoxication procedures (e.g., toxin removal from bile and urine, and extracorporeal purification) and administration of drugs. Chemotherapy included benzylpenicillin or other beta-lactam antibiotics, silymarin complex, thioctic acid, antioxidant drugs, hormones and steroids administered singly, or more usually, in combination. Supportive measures alone and 10 specific treatment regimens were analyzed relative to mortality.

RESULTS

Benzylpenicillin (Penicillin G) alone and in association was the mostfrequently utilized chemotherapy but showed little efficacy. No benefit was found for the use of thioctic acid or steroids. Chi-square statistical comparison of survivors and dead vs. treated individuals supported silybin, administered either as mono-chemotherapy or in drug combination and N-acetylcysteine as mono-chemotherapy as the most effective therapeutic modes. Future clinical research should focus on confirming the efficacy of silybin, N-acetylcysteine, and detoxication procedures.

Enhanced hepatotoxicity and toxic outcome of thioacetamide in streptozotocin-induced diabetic rats

Diabetes is known to potentiate thioacetamide (TA)-induced liver injury via enhanced bioactivation. Little attention has been given to the role of compensatory tissue repair on ultimate outcome of hepatic injury in diabetes. The objective of this study was to investigate the effect of diabetes on TA-induced liver injury and lethality and to investigate the underlying mechanisms. We hypothesized that hepatotoxicity of TA in diabetic rats would increase due to enhanced bioactivation-mediated liver injury and also due to compromised compensatory tissue repair, consequently making a nonlethal dose of TA lethal. On day 0, male Sprague-Dawley rats (250-300 g) were injected with streptozotocin (STZ, 60 mg/kg ip) to induce diabetes. On day 10 the STZ-induced diabetic rats and the nondiabetic rats received a single dose of TA (300 mg/kg ip). This normally nonlethal dose of TA caused 90% mortality in the STZ-induced diabetic rats. At various times (0-60 h) after TA administration, liver injury was assessed by plasma alanine aminotransferase (ALT), sorbitol dehydrogenase (SDH), and liver histopathology. Liver function was evaluated by plasma bilirubin. Cell proliferation and tissue repair were evaluated by [(3)H]thymidine ((3)H-T) incorporation and proliferating cell nuclear antigen (PCNA) assays. In the nondiabetic rat, liver necrosis peaked at 24 h and declined thereafter toward normal by 60 h. In the STZ-induced diabetic rat, however, liver necrosis was significantly increased from 12 h onward and progressed, culminating in liver failure and death. Liver tissue repair studies showed that, in the liver of nondiabetic rats, S-phase DNA synthesis was increased at 36 h and peaked at 48 h following TA administration. However, DNA synthesis was approximately 50% inhibited in the liver of diabetic rats. PCNA study showed a corresponding decrease of cell-cycle progression, indicating that the compensatory tissue repair was sluggish in the diabetic rats. Further investigation of tissue repair by employing equitoxic doses (300 mg TA/kg in the non-diabetic rats; 30 mg TA/kg in the diabetic rats) revealed that, despite equal injury up to 24 h following injection, the tissue repair response in the diabetic rats was much delayed. The compromised tissue repair prolonged liver injury in the diabetic rats. These studies suggest that the increased TA hepatotoxicity in the diabetic rat is due to combined effects of increased bioactivation-mediated liver injury of TA and compromised compensatory tissue repair.

Can alprostadil improve liver failure in HIV-infected patients with severe acute viral hepatitis?

Liver failure with hepatic encephalopathy during an acute viral hepatitis carries a very high mortality. Liver transplantation is the usual treatment, but for poor candidates for transplantation only supportive therapy is available. Two patients with HIV infection developed an acute B hepatitis with liver insufficiency and hepatic encephalopathy. After an alprostadil infusion was begun they improved quickly and made a full recovery. This drug merits further investigation.

Fulminant hepatic failure

Fulminant hepatic failure is a devastating illness that carries considerable mortality and affects patients with previously healthy livers. Although the etiology of FHF remains unclear in a significant number of cases, viral hepatitis and drug-induced liver injury account for the majority of identifiable causes. The clinical presentation varies widely, but is always characterized by the presence of encephalopathy. Markedly elevated transaminases are seen, but do not correlate with extent of liver injury. Prothrombin time, bilirubin, creatinine, and arterial pH are prognostic indicators of survival in FHF. FHF and its consequences must be readily recognized so that appropriate triage and treatment can be administered. All patients should be managed in an intensive care setting pending transfer to a liver transplantation center. Supportive care remains the mainstay of treatment, with liver transplantation reserved for select patients.

Hepatic disorders. Features and appropriate management

The spectrum of liver disease is extremely wide, with many of the underlying disorders having acute and chronic presentations. Most of the underlying pathogenetic mechanisms are accounted for by autoimmune disease, viral infection and toxic insult. The management strategy of any liver disease is a combination of treating the symptoms and complications that arise, as well as drug therapies relevant to the specific underlying diagnosis. Encephalopathy, ascites, spontaneous bacterial peritonitis, variceal bleeding and pruritus are the main complications at which drug therapy is directed, although in some cases it represents only 1 aspect of the overall management. Drug therapy per se is largely ineffective in acute liver failure with the possible exception of acetylcysteine, but many drugs are used in the management of the constituent components of this complex medical emergency. Treatments for specific liver conditions are expanding, especially in the areas of autoimmune and viral disease. The increasing availability and success of liver transplantation has tended to change the emphasis of management, and it is often not appropriate to exhaust the treatment options before referring the patient for transplantation. A comprehensive review of all liver disease is beyond the scope of this article, but hopefully the important principles of management and commonly occurring clinical decisions are discussed.

A multicenter study on the prognosis of fulminant viral hepatitis: early prediction for liver transplantation

To determine the risk of death at an early stage of fulminant viral hepatitis, we created severity indexes drawn from clinical data on the day of development of encephalopathy in 128 patients with fulminant hepatitis B and 103 with fulminant hepatitis non-A, non-B. In fulminant hepatitis B, the risk score was 2.75 x BL + 2.75 x BR + 2.7 x AG + 2.3 x WB + 1.67 x CD + 1.56 x AL - 0.098 x PR - 0.88, where BL is 1 if total bilirubin is higher than 20 mg/dl, BR is 1 if the ratio of total to direct bilirubin exceeds 2.2, AG is 1 if age is above 40 yr, WB is 1 if white blood cell count is less than 4,000 cells/mm3 or more than 18,000 cells/mm3, CD is 1 if a hazardous disease coexists and AL is 1 if ALT is less than 100 times the upper limit of normal (otherwise all are 0), and PR is prothrombin time (percentage of normal value). Using a cutoff score of 0, we found the positive predictive value, negative predictive value and predictive accuracy to be 0.90, 0.86 and 0.89, respectively. Sensitivity and specificity were 0.94 and 0.77, respectively. In fulminant non-A, non-B hepatitis, the risk score was 2.66 x BR + 2.25 x BL + 2.24 x DI + 2.05 x AL +/- 1.38 x AG + 0.00021 x WB - 6.33.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration of hepatic stimulatory substance alone or with other liver growth factors does not ameliorate acetaminophen-induced liver failure

Sixty-two beagle dogs were given three doses of acetaminophen over a period of 24 hr in a fulminant liver failure model that is 70% lethal in 72 hr. Treatment of the animals with hepatic stimulatory substance alone or in a mixture with insulin, transforming growth factor-alpha and insulin-like growth factor II had no effect on mortality. Evidence of maximum regeneration with a mitotic index 20 to 25 times resting was the same in treated and untreated animals. Similarly, the biochemical and hematological indexes of liver injury were unaffected by therapy. These studies illustrate the futility of treating fulminant liver failure with exogenous growth factors that apparently are already present in large amounts in the natural response to liver injury. The results suggest that on-going liver injury by mechanisms other than lack of growth factors is the central problem of fulminant liver failure. If so, provision of regeneration-stimulating substance is an inappropriate therapeutic strategy.

Treatment of severe alcoholic hepatitis by infusion of insulin and glucagon: a multicenter sequential trial

Severe alcoholic hepatitis is still a therapeutic challenge. It has been recently advocated that a 3-wk infusion with insulin and glucagon reduces its short-term mortality rate. A multicenter, randomized, single-blind, sequential trial was designed to compare this treatment with placebo. The triangular boundary was defined with alpha = 0.05, beta = 0.10 and estimated survival at 4 wk of 50% with placebo, 75% with treatment. Patients with biopsy-proven severe alcoholic hepatitis (presence of one or more of three criteria: encephalopathy, prothrombin activity less than or equal to 50%, bilirubinemia greater than or equal to 100 mumol/L) were randomized into two groups; one treatment group received an infusion (12 hr/day) of an association of insulin (30 IU) and glucagon (3 mg), and a control group received an infusion of glucose. Treatments were administered during a 3-wk period, and the mortality rate was noted at 4 wk. The decision to discontinue the trial was reached on the basis of results from the first 44 patients. Overall results were assessed in the 72 patients included at the time of this decision (treatment group: n = 37; control group: n = 35). Fifty-three patients had cirrhosis. No significant differences were noted between the two groups at inclusion on the basis of clinical, laboratory and histological criteria. The mortality rate was not significantly different in the two groups; 10 patients (27%) in the treatment group and 5 patients (14%) in the control group died. Causes of death were similar in the two groups and consisted primarily of gastrointestinal hemorrhage, hepatic failure and infectious events.(ABSTRACT TRUNCATED AT 250 WORDS)