Central nervous system toxicity after liver transplantation. The role of cyclosporine and cholesterol

Cerebral aspergillosis in liver transplantation

Nine cases of cerebral aspergillosis were identified in a series of 44 brains obtained at necropsy from patients who had undergone liver transplantation. In two of these there was dual infection with Candida albicans. The primary focus of infection was invariably in the lungs. One case of pulmonary Aspergillus infection was found with no evidence of cerebral disease. Infection tended to occur in the period soon after transplantation, was associated with high dose steroids, retransplantation, and showed a significant seasonal incidence. Neurological findings were non-specific and only two cases were diagnosed before death. Aspergillus infection soon after transplantation indicates that this organism is a considerable nosocomial hazard, particularly in the winter and spring months. Positive cultures before death are rarely obtained and antifungal treatment should be started on clinical suspicion alone.

The use of 125I-HIPDM for studying tissue response due to toxic effects of cyclosporin-A in rats

125I-HIPDM was used to study the response of various tissues in cyclosporin-A, CyA, treated and control rats. The rats were given 50 mg/kg of CyA for 7 consecutive days. The liver, kidney and heart showed significant increase while the spleen had a pronounced decrease in the uptake of 125I-HIPDM in CyA treated compared to control rats. This difference in the uptake of 125I-HIPDM between CyA treated and control rats is assumed to be the tissue response to toxic effects of CyA. The results indicate that CyA is toxic to liver, kidney, spleen and probably heart. There was no difference in the uptake of 125I-HIPDM in the lung and brain of CyA treated and control rats. This lack of difference is assumed to indicate that CyA does not adversely affect the lung and brain.

Cyclosporine lowers seizure threshold in an experimental model of electroshock-induced seizures in Munich-Wistar rats

We have developed a model of cyclosporin A (CsA) central nervous system toxicity in the Munich-Wistar rat in which CsA, 20 mg/kg/day i.p., produces significant EEG abnormalities and mortality. In the present study we used cohorts of Munich-Wistar rats to assess effects of CsA on the threshold for tonic-clonic electroshock-induced seizures. Rat cohorts were begun on cremephore, CsA-10 mg/kg/day, or CsA-20 mg/kg/day. On day 7 and day 14 of the dosing protocol, cohorts of animals were exposed to maximal electroshock (MES) using a minimal staircase method within each cohort. Multiple logistic regression models were used to determine differences between groups on the relative odds of producing a MES-induced seizure while controlling for other variables. Seizure threshold was significantly affected by shock amperage and body weight, but not by SUN, creatinine, bilirubin, sodium, potassium, weight loss or day the shock was delivered. The odds ratios of seizure induction in the CsA-treated groups versus placebo group were 1.91 for CsA-10 mg/kg/day and 3.63 for CsA 20-mg/kg/d, both statistically significant. These results suggest that cyclosporine lowers seizure threshold and probably increases susceptibility to seizures, the etiology of which may be multifactorial clinically.

Blood concentrations after accidental cyclosporin overdose

Two cases of children are reported with an accidental oral overdose of cyclosporin in whom blood concentrations were monitored. Despite a tenfold oral overdose, the peak blood concentrations of cyclosporin in both patients were only moderately increased above therapeutic levels. Apart from a transient rise in blood pressure in one patient, no toxic effects of cyclosporin were noticed.

Psychiatric aspects of renal transplantation

Despite the growth of heart, liver and bone marrow transplantation, the kidney continues to be the organ most frequently transplanted. Over the years psychiatrists have been active in attempting to understand the adaptational tasks of organ donors and recipients and in evaluating and treating transplant patients. A body of knowledge with regard to renal transplantation has developed. What follows is an update of psychiatric aspects of renal transplantation.

Liver transplantation

Liver transplantation has become an established form of therapy for patients with almost any type of irreversible and severe liver disease. The remarkable success of liver transplantation has resulted from recent advances in immunosuppressive therapy, surgical techniques, and patient selection. Additional progress has been made in the management of the complex postoperative medical complications that may occur. Indeed, liver transplantation has contributed significantly to an improved quantity and quality of life for many patients with liver disease.

Cyclosporine: a review and its specific use in liver transplantation

During the past decade, treatment with cyclosporine, an immunosuppressive agent, has contributed substantially to enhanced allograft and patient survival after liver transplantation. Currently, the 1-year survival rate after liver transplantation is more than 80% in major liver transplantation centers, in contrast with approximately 60% before the availability of cyclosporine. Its predominant immunologic effect is inhibition of lymphokine production and secretion by helper T cells. The use of cyclosporine, however, is associated with numerous adverse effects, the most important of which are nephrotoxicity, hypertension, neurotoxicity, opportunistic infections, and malignant lesions. Acute nephrotoxicity, hypertension, and neurotoxicity usually can be reversed by decreasing the dose of cyclosporine. Measurement of cyclosporine concentrations in the blood is essential for optimization of immunosuppressive therapy and prevention of toxicity.

Intensive-care unit experience in the Mayo liver transplantation program: the first 100 cases

The first 100 liver transplantations at the Mayo Clinic were performed in 83 patients, who required a total of 917 patient days in the intensive-care unit (ICU). The mean duration of stay in the ICU was 5.91 days after liver transplantation and 6.15 days for patients who subsequently required readmission to the ICU. During the immediate postoperative period, hypothermia and hyperglycemia invariably occurred. Later during the initial admission or on readmission to the ICU, there arose the possibility of infections and renal insufficiency. Prompt diagnosis and treatment are necessary for hypertension, hypokalemia, severe metabolic alkalosis, fever, altered mental status, oliguria, and signs of graft failure in liver transplant patients. In our patient series, selective bowel decontamination minimized the occurrence of gram-negative and fungal sepsis, and use of antihypertensive agents and correction of coagulopathies may have decreased the risk of intracranial bleeding in patients with hypertension and clotting defects. Anticipation of potential conditions postoperatively and early implementation of treatment are key factors in the successful ICU management of patients who have undergone liver transplantation.

The first 100 liver transplantations at the Mayo Clinic

Between March 1985 and June 1987, the first 100 liver transplantations at the Mayo Clinic were performed in 83 patients (primarily adults). The most frequent diagnoses were chronic active hepatitis (in 24 patients), primary sclerosing cholangitis (in 22), and primary biliary cirrhosis (in 20). The median operating time was 406 minutes, and the median usage of erythrocytes was 13.2 units. A venovenous bypass was used in all patients older than 10 years of age. Hepatic artery thrombosis occurred in 10% of the 100 transplants. A choledochocholedochostomy was done in 58 patients and a choledochojejunostomy in 25 patients. Revision of the biliary anastomosis was necessary in 9 of the 83 patients (11%). Rejection, diagnosed by clinical and histologic criteria, occurred in 50 patients (60%) and was treated with a corticosteroid bolus, followed by OKT3 (monoclonal antibody) treatment if necessary. Selective bowel decontamination helped prevent infections; only 16 bacteremias occurred, 1 of which was caused by a gram-negative organism. Fungal infections were rare. Cytomegalovirus infection occurred in 47 patients (57%). Of the 83 patients, 16 required retransplantation, in 11 of whom graft rejection had occurred. One- and 2-year patient survival was 83% and 70%, respectively. Although problems still remain, liver transplantation is a reasonable option for patients with end-stage liver disease.

[Liver transplantation in adults: postoperative management and development during the first months]

Recent improvements in the results of orthotopic liver transplantation (OLT) have made this a well-accepted treatment for patients with severe hepatic failure. Current problems encountered following OLT are discussed. Immediate complications comprise surgical bleeding, primary graft non-function, and graft failure due to hepatic artery occlusion. Secondary complications are frequent. Surgical ones include biliary and vascular (hepatic artery thrombosis most often) problems, as well as intra-abdominal abscesses associated with gastrointestinal perforation, biliary leak, graft ischaemia or an infected haematoma. 40% of patients having undergone OLT will be reoperated on, 2/3 of them within 3 months. Non-surgical complications are mostly pulmonary. The risk of pneumonitis is increased by prolonged mechanical ventilation; it is always potentially disastrous in the immunosuppressed, transplanted patient. Hypertension is also often seen in the early postoperative period; it requires prompt treatment. Early renal impairment after OLT is common, and of better prognosis than late onset renal failure, which is generally associated with shock, graft failure, sepsis or use of nephrotoxic agents. Seizures, usually only one, occur in about 10% of patients; recovery is complete. Encephalopathy with intracranial oedema related to fulminant hepatitis has a worse prognosis, but survival figures are quite encouraging. Three type of rejection are described after OLT: 1) severe accelerated rejection (very rare), 2) acute rejection encountered in about 70% of patients over the first 3 months, and 3) late rejection, which can lead to the vanishing bile duct syndrome (VBDS). Diagnosis of rejection is made by liver biopsy. Prophylactic immunosuppression includes cyclosporin, methylprednisolone and azathioprine. Cyclosporin toxicity and drug interactions are reviewed. Treatment of acute rejection episodes comprises an initial bolus of high doses of corticoid drugs; if there is no response, antilymphocyte globulin or monoclonal antibodies may have to be used. Infection is the main cause of death following OLT. Early infections, mostly intra-abdominal and pulmonary, are bacterial or fungal. Vital (especially CMV) and other opportunistic infections occur generally after the second week. Retransplantation, carried out in 10 to 25% of patients, may be urgent in case of primary graft failure, or hepatic artery thrombosis associated with graft failure, or hepatic artery thrombosis associated with graft failure. Other indications are early graft rejection with severe hepatic dysfunction, chronic rejection with severe VBDS, and recurrence of the initial disease.

Liver transplantation

The 1-year survival rates of around 70% that are now being achieved have resulted in the acceptance of liver transplantation as a treatment for end-stage liver disease. The number of patients undergoing transplantation is increasing rapidly and the indications are widening. More patients are being transplanted for acute liver failure following the recent encouraging reports of successful grafting in this condition. The proportion of patients transplanted for liver cancer is falling as it becomes apparent that 80% of patients will die from recurrent disease. The selection of candidates and timing of transplantation continue to pose difficult clinical problems. Although the surgical and anaesthetic aspects of liver transplantation have been greatly improved, the 30-day mortality remains high at around 30% and postoperative complications, especially infection and rejection, continue to be major problems. However, rehabilitation is excellent for most patients and liver transplantation should no longer be considered an experimental procedure.

Cyclosporine, low-density lipoprotein, and cholesterol

Lipoproteins are known to be able to transport a variety of drugs. This report suggests that low-density lipoprotein not only functions as an important carrier of cyclosporine in plasma but also facilitates transport of cyclosporine across the cell membrane by means of the low-density lipoprotein receptor. Such a mechanism would explain (1) the similar tissue distribution of cyclosporine and the low-density lipoprotein receptor, (2) the increase in immunosuppression and toxicity with low total serum cholesterol levels, and (3) the relative absence of immunosuppression and toxicity with high levels of cyclosporine in the blood in patients with hypertriglyceridemia. In addition to receptor-mediated uptake, a disturbance of the blood-brain barrier is suggested as an explanation of the high frequency of cyclosporine-induced central nervous system toxicity after liver transplantation. Cyclosporine-induced inhibition of the mitochondrial steroid 26-hydroxylase, an enzyme involved in the formation of bile acids from cholesterol and deficient in patients with cerebrotendinous xanthomatosis, may cause or contribute to the observed central nervous system toxicity. It also may explain the similar clinical features of cyclosporine-induced central nervous system toxicity and cerebrotendinous xanthomatosis.

Time-dependent pharmacokinetics and toxicity of cyclosporine

Although the circadian pattern of cyclosporine (CSA) pharmacokinetics and toxicity has been described previously in both animal and clinical studies, the mechanism of this action is unknown. The present study compared the pharmacokinetics and experimental nephrotoxicity of chronic CSA in both the genetically-hyperlipidemic rat model and the lean litter-mate. Once daily dosing (25 mg/kg via gavage) was either at the start of the active (1900) or inactive (0700) cycle (Nov 1987 to Jan 1988). Serial serum samples following the final dose were assayed by both polyclonal (nonspecific) and monoclonal (specific for parent CSA) RIA. Renal toxicity was assessed by 24-hr creatinine clearances, fractional clearances of sodium and potassium, and inulin clearances (CIN). Despite a greater than 2-fold increase in serum CSA concentrations, there were no changes in renal function in obese rats dosed at the start of the active period compared to the inactive period. Furthermore, mean CIN of the lean group administered drug at the start of the active period was not significantly different from time-matched placebo-treated lean rats. However, there was an 80% drop in CIN in rats treated with CSA at the start of the inactive period compared to control group. There were no differences in electrolyte handling. Insulin concentrations, independent of time of dosing, were markedly elevated in obese rats dosed CSA compared to placebo-treated obese or both lean groups. Serum triglyceride levels were significantly correlated with pharmacokinetic parameters of total but not parent CSA. In summary, significant differences in toxicity were observed due to time of dosing and lipid profiles. Although the mechanism of this action remains unclear, it appears that increased non-fasting serum triglyceride levels following the active period most likely reduced CSA distribution into kidney tissue preventing the dose-limiting nephrotoxicity.