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

Impact of dyslipidaemia in renal transplant recipients

The evidence that lipid disorders in patients following renal transplantation play a major role in the pathogenesis of atherosclerosis and chronic renal allograft rejection is circumstantial. The absolute rate of clinical vascular disease and cardiovascular complications in transplant patients, the high prevalence of an atherogenic lipid profile and the evidence from the large HMG-CoA reductase inhibitor (statin) regression trials in the general population suggest that lipid lowering treatment is necessary in most patients after renal transplantation. Furthermore, animal models and observational studies in patients have found correlations between plasma lipid levels and both acute and chronic rejection. Animal transplant models and clinical trials in heart transplant patients also suggest that statin treatment decrease the incidence of chronic rejection in a manner that may also be independent of lipid lowering. Although the mechanisms behind this protective effect remains unclear, statins may be the first agents to be effective in preventing chronic rejection and in reducing the rate of cardiovascular complication in renal transplant recipients.

Cyclosporine induces epileptiform activity in an in vitro seizure model

PURPOSE

Cyclosporine (CSA) toxicity represents a common cause of seizures in transplant patients, but the specific mechanisms by which CSA induces seizures are unknown. Although CSA may promote seizure activity by various metabolic, toxic, vascular, or structural mechanisms, CSA also has been hypothesized to modulate neuronal excitability directly. The objective of this study was to determine if CSA exerts direct epileptogenic actions on neurons in an in vitro seizure model.

METHODS

Combined hippocampal-entorhinal cortex slices from juvenile rats were exposed directly to artificial cerebrospinal fluid (ACSF) containing either (a) 1.0 mM magnesium sulfate (control), (b) 1.0 mM sodium sulfate (low-magnesium), or (c) 1.0 mM magnesium sulfate + CSA (1,000-10,000 ng/ml). Spontaneous and evoked extracellular field potentials were recorded simultaneously from the dentate gyrus (DG) and CA3 hippocampal regions. Evoked synaptic responses were elicited by stimulation of the entorhinal cortex/perforant pathway.

RESULTS

CSA elicited spontaneous or stimulation-induced epileptiform activity in the DG or CA3 region of approximately 40% of slices, consisting of brief repetitive "interictal" discharges or prolonged stereotypical "ictal" discharges. Mean latency to epileptiform activity was approximately 100 min after onset of CSA application. The interictal discharges were inhibited by the non-NMDA antagonist, NBQX. Similar epileptiform activity was observed in low-magnesium ACSF without CSA. In control ACSF alone, epileptiform activity was not seen, except for rare spontaneous potentials in the DG.

CONCLUSIONS

Direct effects of CSA on neuronal excitability and synaptic transmission may contribute to seizures seen in clinical CSA neurotoxicity.

Immunosuppressive-associated leukoencephalopathy in organ transplant recipients

Immunosuppressive-associated leukoencephalopathy is a significant complication of cyclosporine (CsA) or tacrolimus therapy. However, the precise time of onset, role of putative risk factors, differences, if any, in presentation in various types of organ transplantation and outcome of this entity, remain poorly defined. Fifty cases of immunosuppressive-associated leukoencephalopathy reported in the literature in organ transplant recipients, were reviewed. Of 50 cases, 31 occurred in liver, 8 in renal, 6 in lung, and 5 in heart transplant recipients. Median time to onset was 28 days (range 3-1512 days); 82% occurred within 90 days of transplantation. Lesions tended to occur earlier in the liver transplant recipients, compared with other organ transplant recipients (median 9 vs. 29 days, P=.19). Seizures 74%, altered mental status 50%, and visual abnormalities 28% were the most frequently presenting features. Ten percent of the patients had fever with no documented source of infection. Systemic hypertension (P=.001), and lesions in the presence of therapeutic drug levels (P=.11) were more likely to occur with CsA than tacrolimus. Neuroimaging and clinical abnormalities were reversible on cessation or reduction of CsA or tacrolimus in all but two cases. Resolution of neurologic signs/symptoms occurred a median of 4 days and neuroimaging abnormalities in a median of 20 days on reduction/cessation of the drug. Immunosuppressive-associated leukoencephalopathy is a unique entity that can usually be diagnosed on the basis of its distinctive time of onset, and clinical and neuroimaging characteristics, and it is potentially reversible if promptly diagnosed. Despite identical clinical presentation of this syndrome in the recipients of CsA and tacrolimus, above noted variations in risk factors suggest that a difference in pathophysiologic mechanism may exist.

Continuous infusion of cyclosporin A postinjury significantly ameliorates cortical damage following traumatic brain injury

Traumatic brain injury (TBI) results in the rapid necrosis of cortical tissue at the site of injury. In the ensuing hours and days, secondary injury exacerbates the original damage resulting in significant neurological dysfunction. Recent reports from our lab demonstrate that a bolus injection of the immunosuppressant cyclosporin A (CsA) is neuroprotective following TBI. CsA transiently inhibits the opening of the mitochondrial permeability transition pore and maintains calcium homeostasis in isolated mitochondria. The present study utilized a unilateral controlled cortical impact model of TBI to assess whether the neuroprotective effects of CsA could be extended by chronic infusion. Adult rats were subjected to a moderate (2 mm) cortical deformation and the extent of cortical damage was assessed using modern stereological techniques. Animals were administrated a 20 mg/kg intraperitoneal bolus of CsA or vehicle 15 min postinjury and osmotic minipumps were implanted subcutaneously to deliver CsA (4.5 or 10 mg/kg/day) or vehicle. All animals receiving CsA demonstrated a significant reduction in lesion volume, with the highest dose offering the most neuroprotection (74% reduction in lesion volume). These results extend our previous findings and demonstrate that chronic infusion of CsA is neuroprotective following TBI. These findings also suggest that the mechanisms responsible for tissue necrosis following TBI are amenable to manipulation.

The novel immunosuppressant SDZ-RAD protects rat brain slices from cyclosporine-induced reduction of high-energy phosphates

1. SDZ-RAD, 40-O-(2-hydroxyethyl)-rapamycin, is a novel macrolide immunosuppressant. Because of its synergistic interaction, SDZ-RAD is under clinical investigation as immunosuppressant in combination with cyclosporine after organ transplantation. Neurotoxicity is a critical side-effect of cyclosporine. 2. We studied the effect of SDZ-RAD and its combination with cyclosporine on high-energy phosphates, phosphocreatine (PCr) and nucleoside triphosphates (NTP), in brain slices using 31P-magnetic resonance spectroscopy (MRS). 3. Cyclosporine significantly reduced high-energy phosphates after 2 h in a dose-dependent manner (100 micrograms l-1: 93 +/- 3% of control (NTP), 91 +/- 3% (PCr); 500 micrograms l-1: 84 +/- 2% (NTP), 73 +/- 2 (PCr); 5000 micrograms l-1: 68 +/- 3% (NTP), 55 +/- 5% (PCr); n = 6; P < 0.02). 4. In contrast, after perfusion for 2 h, SDZ-RAD (500 micrograms l-1 and 5000 micrograms l-1) significantly increased high-energy phosphate concentrations in the brain slices (P < 0.02). Even at the lowest concentration, SDZ-RAD protected brain energy metabolism against cyclosporine toxicity: 100 micrograms l-1 SDZ-RAD + 5000 micrograms l-1 cyclosporine: 86 +/- 3% (NTP), 83 +/- 7% (PCr), n = 3, P < 0.03 compared to cyclosporine alone. 5. As evaluated using an algorithm based on Loewe isobolograms, the effects of SDZ-RAD/cyclosporine combinations on brain energy reduction were antagonistic. Both drugs were found in mitochondria using h.p.l.c-MS analysis. 6. We conclude that cyclosporine inhibits mitochondrial high-energy phosphate metabolism, which can be antagonized by SDZ-RAD.

Increased incidence of neurological complications in patients receiving an allogenic bone marrow transplantation from alternative donors

OBJECTIVE

To compare the frequency and type of neurological complications after bone marrow transplantation (BMT) with an HLA identical unrelated donor or a mismatched related donor (alternative donors) to the neurological complications after matched sibling BMT for standard and high risk leukaemia or myelodysplastic syndromes.

METHODS

Retrospective analysis of consecutively treated patients with (a) BMT from alternative donors (n=39), (b) treated with matched sibling BMT for standard risk leukaemia, myelodysplastic syndromes, or aplastic anaemia (n=53), and (c) treated with matched sibling BMT for high risk leukaemia, myelodysplastic syndromes, or aplastic anaemia (n=49).

RESULTS

A total of 72 neurological complications were found. Most of these occurred within the first 6 months after transplant. Thirty six patients developed a severe neurological complication: 17 Alternative donor patients (44%) by contrast with six standard risk patients (11%) and 13 high risk patients (27%; p<0.005). The most frequent complication was a metabolic encephalopathy occurring in 18% of patients. Most of the encephalopathies were caused by either the transplant procedure, cyclosporin, systemic infections, microangiopathic thrombopathy, or by complications induced by graft versus host disease. Infections of the CNS developed in 9% of patients, cerebrovascular lesions in 3%.

CONCLUSIONS

Severe neurological complications are more frequent after BMT from alternative donors. This is mainly due to increased treatment related morbidity and to more profound immunosuppression after BMT from alternative donors.

Physiologically based pharmacokinetics of cyclosporine A: reevaluation of dose-nonlinear kinetics in rats

The disposition kinetics of Cyclosporine A (CyA) in rat, based on measurement in arterial blood, appeared dose-linear over a wide i.v. dose range (1.2-30 mg/kg). Physiologically based pharmacokinetic (PBPK) analysis, however, demonstrated that this was an apparent observation resulting from counterbalancing nonlinear factors, such as saturable blood and tissue distribution, as well as clearance (CLb). A PBPK model was successfully developed taking into account these multiple nonlinear factors. Tissue distribution was distinctly different among various organs, being best described by either a linear model (muscle, fat; Model 1), one involving instantaneous saturation (lung, heart, bone, skin, thymus; Model 2), noninstantaneous saturation (kidney, spleen, liver, gut; Model 3), or one with saturable efflux (brain; Model 4). Overall, the whole body volume of distribution at steady state for unbound CyA (Vuss) decreased with increasing dose, due at least in part to saturation of tissue-cellular cyclophilin binding. Clearance, essentially hepatic, and described by the well-stirred model, was also adequately characterized by Michaelis-Menten kinetics, Km 0.60 microgram/ml. In model-based simulations, both volume of distribution at steady state (Vss,b) and CLb varied in a similar manner with dose, such that terminal t1/2 remained apparently unchanged; these dose responses were attenuated by saturable blood binding. CyA concentration measured in arterial blood was not always directly proportional to the true exposure, i.e., unbound or target tissue concentrations. The PBPK model not only described comprehensively such complicated PK relationships but also permitted assessment of the sensitivity of individual parameters to variation in local nonlinear kinetics. Using this approach, dose-dependent CyA uptake into brain was shown to be sensitive to both active and passive transport processes, and not merely the affinity of the active (efflux) transporter at the level of the blood-brain barrier.

Cyclosporine levels in cerebrospinal fluid after liver transplantation

BACKGROUND

The mechanisms underlying cyclosporine neurotoxicity remain undefined. Particularly, whether cyclosporine (CyA) enters cerebrospinal fluid (CSF) or brain tissue is disputed.

METHODS

We analyzed CSF from 17 lumbar punctures performed in 14 liver recipients receiving CyA and experiencing neurological complications, fever of unknown origin, seizures, or altered mental status. Whole blood samples were assayed for CyA and its metabolites. Liver function tests, serum electrolytes, and cholesterol were also analyzed.

RESULTS

Four patients had cyclosporine metabolites in the CSF. These patients had acute renal insufficiency and significantly higher blood urea nitrogen (BUN) and total and direct bilirubin and alkaline phosphatase levels than patients without CyA metabolites in CSF (P < 0.05). Whole blood levels of CyA parent drug were similar between groups. Levels of CyA metabolites in the blood were significantly higher in patients with metabolites in the CSF. CyA parent drug was undetectable in CSF in both groups.

CONCLUSIONS

This is the first prospective report of CyA metabolites in the CSF of transplant recipients. Acute renal insufficiency and high bilirubin levels may be associated with entry of CyA metabolites into the CSF.

Cyclosporin A and imipenem associated seizure activity in allogeneic bone marrow transplantation patients

Imipenem is an antibiotic used with cilastatin in the bone marrow transplant (BMT) setting. Cyclosporin A (CsA) is an immunosuppressive agent. Seizures can be seen with both imipenem/cilastatin and CsA. Our hypothesis for study was that CNS toxicity and seizures are increased by the concomitant administration of CsA and imipenem/cilastatin. Between December of 1989 and 1996, all of the 166 stem cell BMTs performed at Mount Sinai Hospital in New York were evaluated for this study. Three groups were studied: 77 patients received CsA alone (Group 1); 89 patients received imipenem/cilastatin, and of these, 45 received concomitant CsA (Group 2); and 44 patients who underwent autologous BMT received imipenem/cilastatin only (Group 3). We observed a total of 5 seizure episodes. There were no statistical differences in frequency between the groups. Adverse effects may be difficult to relate to a particular drug, especially for patients on multidrug regimens but the use of imipenem/cilastatin and CsA did not cause a significant rise in the frequency of seizures when compared to CsA alone.

Cyclosporin A significantly ameliorates cortical damage following experimental traumatic brain injury in rodents

Experimental traumatic brain injury (TBI) results in a rapid and significant necrosis of cortical tissue at the site of injury. In the ensuing hours and days, secondary injury exacerbates the original damage, resulting in significant neurological dysfunction. Young adult animals were treated either 5 min before or immediately after a cortical injury with the immunosuppressant cyclosporin A (CsA). All animals treated with CsA demonstrated a significant reduction in the amount of cortical damage 7 days following TBI. The effect was observed in adult rats and in two different strains of adult mice following systemic administration of the drug. Cyclosporin A has known effects on mitochondria by inhibiting the opening of the permeability transition pore and maintaining calcium homeostasis. These results with a clinically approved drug demonstrate an almost 50% reduction in lesion volume and suggest that the mechanisms responsible for tissue necrosis following TBI are amenable to manipulation. Since CsA also has known interactions with calcineurin and may be providing neuroprotection through that mechanism, additional animals were treated with the immunosuppressant FK 506. FK 506 failed to protect against the cortical damage. Amelioration of cortical damage with CsA indicates that pharmacological therapies can be devised that will significantly alter neurological outcome after injury.

Inhibition of GABA system involved in cyclosporine-induced convulsions

In this study, we attempted to clarify the mechanisms mediating cyclosporine-evoked convulsions. Cyclosporine (50 mg/kg, i.p.) significantly enhanced the intensity of convulsions induced by bicuculline (GABA receptor antagonist), but not those induced by strychnine (glycine receptor antagonist), N-methyl-D-aspartic acid, quisqualic acid or kainic acid (glutamate receptor agonists). Bicuculline plus cyclosporine-induced convulsions were significantly suppressed by an activation of GABAergic transmission with diazepam, phenobarbital and valproate. The GABA turnover estimated by measuring aminooxyacetic acid-induced GABA accumulation in the mouse brain was significantly inhibited by cyclosporine (50 mg/kg, i.p.). When cultured rat cerebellar granule cells were exposed to 1 microM cyclosporine for 24 hr, the specific [3H]muscimol (10 nM) binding to intact granule cells decreased to 53% of vehicle controls. The present study provides the first evidence suggesting that cyclosporine inhibits GABAergic neural activity and binding properties of the GABAA receptor. These events are closely related to the occurrence of adverse central effects including tremors, convulsions, coma and encephalopathy under cyclosporine therapy.

Role of circulating lipid abnormalities in chronic renal allograft rejection

The evidence that circulating lipid abnormalities may play a role in the pathogenesis of chronic renal allograft rejection is tantalizing but circumstantial. In animal models of cardiac and aorta allograft rejection, lipogenic diets accelerate vascular injury, and treatment with 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors reduce vascular injury. Histological studies have demonstrated foam cells and apolipoprotein deposits in the intima of arteries from chronically rejecting human kidneys. Observational studies have found correlations between plasma lipid levels and both acute and chronic rejection. The association between lipid levels and acute rejection in cyclosporine A (CsA)-treated renal transplant recipients suggests the possibility that plasma lipids may influence the immunosuppressive effects of CsA by modulating the lipoprotein-free levels of CsA. If true, such an effect could also explain the result of recent controlled trials showing that HMG-CoA reductase inhibitors reduced graft coronary artery disease and that they prolonged survival in heart transplant recipients. In any case, the hypothesis that circulating lipid abnormalities contribute to chronic renal allograft rejection deserves further testing in well-designed, clinical trials.

Effect of cyclosporin A or tacrolimus on the function of blood-brain barrier cells

Recently, it has been reported that continuous treatment with cyclosporin A or tacrolimus induces encephalopathy in transplant patients. The mechanism of immunosuppressant-induced encephalopathy is unclear. We investigated the cytotoxicity to brain capillary endothelial cells and the effect of these two drugs on P-glycoprotein function using mouse brain capillary endothelial (MBEC4) cells. The transcellular transport of [3H]sucrose was significantly increased and the cellular viability, based on 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay and trypan blue exclusion test, was decreased by cyclosporin A (approximately 50% at 5 microM; P<0.005), while tacrolimus showed a much smaller effect. These findings indicate that the toxicity of cyclosporin A was greater than that of tacrolimus. The uptake of [3H]vincristine, a substrate of P-glycoprotein, was increased by these two drugs. The expression of P-glycoprotein in MBEC4 cells was reduced, but there was no effect on mdr1b mRNA levels. The decrease in the expression of P-glycoprotein may be due to the inhibition of the turnover of P-glycoprotein, which involves translation. In conclusion, the direct cytotoxic effect on the brain capillary endothelial cells and the inhibition of P-glycoprotein may be partly involved in the occurrence of immunosuppressant-induced encephalopathy.

Central nervous system lesions in liver transplant recipients: prospective assessment of indications for biopsy and implications for management

BACKGROUND

Precise diagnosis of central nervous system (CNS) lesions in liver transplant recipients remains problematic. Brain biopsies are often not feasible as a result of coagulopathy. We sought to determine whether selected clinical or radiologic characteristics can predict the likely etiology of CNS lesions in liver transplant recipients and thus obviate the need for diagnostic brain biopsies.

METHODS

A 4-year prospective, observational, cohort study was conducted at liver transplant centers at four geographically diverse medical institutions. A total of 1730 consecutive liver transplant recipients were evaluated for CNS lesions; 60 patients with radiologically documented CNS lesions comprised the study sample.

RESULTS

Vascular events (52%, 31/60), infections (181%, 11/60), immunosuppressive associated leukoencephalopathy (12%, 7/60), central pontine myelinolysis (8%, 5/60), and malignancy (3%, 2/60) were the predominant etiologies of CNS lesions. CNS lesions were most likely to occur within 30 days of transplantation (43%, 26/60); central pontine myelinolysis, subdural hematoma, acute infarcts, and Aspergillus brain abscesses were the predominant etiologies during this time. All brain abscesses were fungal; 73% (8/11) of these patients concurrently had documented extraneural (pulmonary) infection as a result of the same fungal pathogen. Thus, a diagnostic brain biopsy is not warranted in these patients. Patients on dialysis were more likely to have ischemic or infectious CNS lesions (P=0.03). Vascular events were more likely to occur in repeat transplant recipients (P=0.03). Twenty-five percent (15/60) of the CNS lesions occurred more than 1 year after transplantation; small vessel ischemic lesions, malignancy, or non-Aspergillus fungal brain abscesses accounted for all such lesions.

CONCLUSIONS

A presumptive etiologic diagnosis can be established in a vast majority of CNS lesions in liver transplant recipients based on identifiable presentation that includes time of onset, unique risk factors, and neuroimaging characteristics. Empiric therapy of brain abscesses in liver transplant recipients should include antifungal and not antibacterial agents.

Cyclosporine-induced migraine with severe vomiting causing loss of renal graft

Successful use of cyclosporine in organ transplant can be associated with unwanted side-effects that can affect graft function. We report three kidney transplant recipients in whom severe migraine headache occurred as a side-effect of cyclosporine therapy. This endangered graft survival in all three and eventually led to loss of graft in two.

Intensive Care of the Intra-Abdominal Organ Transplant Recipient

The postoperative care of a patient who receives an intra-abdominal organ transplant is in some ways simi lar to that of any major intra-abdominal procedure. However, certain features unique to organ transplanta tion, such as the variable functional status of the newly transplanted graft, complications that are specific to the organ transplanted, and the side effects from immuno suppressive drugs, suggest that transplantation inten sive care is a distinct subspecialty in critical care medicine. Today, the majority of patients receiving an intra-abdominal transplant will have a relatively uncom plicated postoperative course. However, preoperative disposition, intraoperative misadventure, or immediate postoperative difficulty will require the availability of an intensivist experienced in transplantation. The future of intra-abdominal transplantation will be highly depen dent on progress in immunotherapy. Newer, more spe cific immunomodulators with fewer nonimmune toxici ties should result in improved organ receptance, less graft dysfunction, and improved patient survival.

Cyclosporin A and brain excitability studied in vitro

PURPOSE

Seizures are frequently observed after organ transplantations. This has been attributed to a direct effect of cyclosporin A (CsA) on the brain, although other mechanisms may also be of importance. The aim of this study was to investigate possible acute and direct effects of CsA on neuronal excitability.

METHODS

Female rat hippocampal slices were perfused with CsA solutions containing 400 (n = 4), 1,000 (n = 4), 2,000 (n = 6), 8,000 (n = 8) microg/L CsA or control (n = 8) for 30 min, or penicillin, 2,000 IE/ml (n = 7). Actual concentrations of CsA were measured in the perfusate drawn from the slice chamber. To study CsA accumulation in the slices, uptake of radioactive CsA was measured in 12 living and 11 dead slices.

RESULTS

Despite a significant accumulation of CsA in the living neuronal slices, no effects were observed on prevolley, field excitatory postsynaptic potential (fEPSP), or population spike amplitude. Penicillin, however, led to epileptiform activity within 10 min in all cases. Concentrations of CsA in the perfusate from the slice chamber were about half the calculated levels, demonstrating that the slices had been exposed to actual CsA concentrations in the range of approximately 200-4,000 microg/L CsA.

CONCLUSIONS

Our results demonstrate a lack of acute effects of CsA on neuronal excitability within clinically relevant concentrations despite an active accumulation of the drug in the slices. Long-term effects on brain tissue, indirect metabolic effects, or synergistic effects may be responsible for the neurotoxicity of the drug.

Cyclosporin A acute encephalopathy and seizure syndrome in childhood: clinical features and risk of seizure recurrence

Cyclosporin A is associated with an acute encephalopathy including seizures and alterations in mental status, herein referred to as cyclosporin A acute encephalopathy and seizure syndrome. The clinical history, electroencephalogram (EEG), and neuroimaging findings in 19 children with cyclosporin A acute encephalopathy and seizure syndrome over a 10-year period were reviewed in order to delineate clinical characteristics, imaging features, and to determine the risk of seizure recurrence in this population. All 19 had motor seizures associated with other features of cortical and subcortical dysfunction. The acute mean cyclosporin A level was 342 microg/L, but was within the "therapeutic" range in five cases. Brain imaging by computed tomography (CT) or magnetic resonance imaging (MRI) in the acute or subacute phase revealed lesions characteristic of cyclosporin A toxicity in 14 cases. Acute EEG abnormalities were present in all and included epileptiform discharges or focal slowing. Patients were followed for a median of 49 months (1-9 years). Follow-up imaging (n = 10) showed lesion resolution or improvement in the majority while EEG (n = 10) had normalized in only three. Seizures recurred in six patients and only in those with persistent EEG or imaging abnormalities. No patient had a second episode of cyclosporin A associated neurotoxicity or seizure. It appears that a significant risk of seizure recurrence exists following cyclosporin A acute encephalopathy and seizure syndrome and primarily in those children with persistent EEG or imaging abnormalities.

Medication induced gingival overgrowth

A number of idiopathic, pathological and pharmacological reactions may result in an overgrowth of the gingiva. This review concentrates on those overgrowths associated with various pharmacological agents. The pharmaco-kinetics and side effects of each drug associated with gingival overgrowth are discussed along with the clinical and histological features and treatment. By examining the possible pathogeneses for these overgrowths we propose a unifying hypothesis for the causation based around inhibition of apoptosis and decreased collagenase activity modulated by cytoplasmic calcium.

Cyclosporine A affects open field behavior in DA rats

Since the introduction of Cyclosporine A (CsA) for immunosuppression in solid-organ transplantation, the rate of allograft rejection has decreased substantially. However, treatment with CsA induces neuropsychological complications in patients, including affective disorders such as anxiety, disorientation, depression, aggression, paranoia, and apathy. These CsA-induced affective side effects cannot be extensively studied in humans. Therefore, this study investigates the effects of intraperitoneal CsA (20 mg/kg) injections on the open-field behavior of male Dark Agouti (DA) rats 1, 6, 12, and 23 h after drug administration on 3 consecutive days. CsA induced an increase in emotionality in DA rats 6 h after injection, reflected by decreased ambulatory activity in the open field and increased defecation. In addition, a decrease in rearing activity was observed 12 h after CsA administration. These behavioral alterations are discussed in the view of changes in cytokine profiles induced by CsA.

Role of plasma lipoproteins in modifying the biological activity of hydrophobic drugs

The plasma lipoprotein distribution of potential drug candidates is not commonly studied. For some hydrophobic drug candidates, attainment of similar plasma free drug levels has not been associated with uniform production of pharmacological activity in different animal species. It is well-known that plasma lipoprotein lipid profiles vary considerably between different animal species. In addition, human disease states can significantly influence plasma lipoprotein profiles, resulting in altered therapeutic outcomes. Current research has shown that lipoprotein binding of drug compounds can significantly influence not only the pharmacological and pharmacokinetic properties of the drug, but the relative toxicity as well. Elucidation of drug distribution among plasma lipoproteins is expected to yield valuable insight into factors governing the pharmacological activity and potential toxicity of the drug. This paper will present an historical perspective and summarize the latest research in the area of lipoprotein-drug interactions.

Occipital lobe seizures as the major clinical manifestation of reversible posterior leukoencephalopathy syndrome: magnetic resonance imaging findings

PURPOSE

Reversible posterior leukoencephalopathy syndrome (RPLS) is an increasingly recognized brain disorder most commonly associated with malignant hypertension, toxemia of pregnancy, or the use of immunosuppressive agents. When associated with acute hypertension, RPLS typically occurs concurrently with the fulminant clinical syndrome of hypertensive encephalopathy. We describe occipital lobe seizures, in the setting of only moderate elevations of blood pressure, as the major clinical manifestation of RPLS.

METHODS

Two patients from the Dent Neurologic Institute are presented with clinical and magnetic resonance imaging (MRI) correlation.

RESULTS

New onset secondarily generalized occipital seizures were noted, with MRI findings consistent with RPLS. Both of the patients had chronic renal failure and a moderate acute exacerbation of chronic hypertension. Other features of hypertensive encephalopathy were lacking, such as headache, nausea, papilledema, and an altered sensorium. Magnetic resonance imaging (MRI) showed edematous lesions primarily involving the posterior supratentorial white matter and corticomedullary junction, consistent with RPLS. With lowered blood pressure, the MRI lesions resolved and the patients became seizure-free without requiring chronic anticonvulsant therapy.

CONCLUSIONS

Occipital seizures may represent the only major neurologic manifestation of RPLS due to acute hypertension, especially in patients with renal failure. Other evidence of hypertensive encephalopathy, such as cerebral signs and symptoms, need not be present. Blood pressure elevations may be only moderate. Early recognition of this readily treatable cause of occipital seizures may obviate the need for extensive, invasive investigations. Despite the impressive lesions on MRI, prompt treatment of this disorder carries a favorable prognosis.

Immunosuppressant neurotoxicity in liver transplant recipients. Clinical challenges for the consultation-liaison psychiatrist

Neuropsychiatric problems are common among liver transplant recipients, and immunosuppressant neurotoxicity is an important etiologic factor in the posttransplant period. Four typical cases of immunosuppressant neurotoxicity are presented from the clinical experience of the University of California, Los Angeles-Dumont Liver Transplant program. All patients presented with acute behavioral symptoms and received urgent psychiatric consultation; each proved to be suffering from a variant of immunosuppressive-related neurotoxicity. Correlative neuroimaging studies and descriptions of clinical course are included. Psychiatrists are urged to become familiar with the signs, symptoms, differential diagnosis, neuroimaging findings, and management of immunosuppressive neurotoxicity and secondary psychiatric disorders in solid organ recipients.

Cognitive side effects of medications

Iatrogenically induced cognitive deficits are common with pharmacological therapy. The deficits may range from gross encephalopathy with delirium to subtle subjective alterations (e.g., mood and perception of well being). The risks are increased for certain drug types, polypharmacy, the elderly, and patients with dementia or metabolic abnormalities. This review examines methodological concerns and the neuropsychological data on cognitive side effects across a variety of commonly used medicines in clinical practice.

Side effects of immunosuppressant therapies used in neurology

This article provides an overview of the clinically relevant complications of the main immunosuppressants currently used in the treatment of neurologic disorders with suspected or established immune etiology. The most serious complications are discussed in detail, including pathophysiology and preventative measures. An intimate knowledge of these complications proves helpful in the day to day practice of the neurologist supervising immunotherapy.

Enhancement of serotonergic neural activity contributes to cyclosporine-induced tremors in mice

A single cyclosporine injection (50 mg/kg, i.p.) significantly enhanced harmine- but not oxotremorine-induced tremors in mice. This potentiation became more apparent when cyclosporine (50 mg/kg, i.p.) was administered once a day for seven days. These findings suggest an involvement of monoaminergic mechanisms in cyclosporine-induced tremors. The effects of cyclosporine were examined on the dynamics of noradrenaline, dopamine and serotonin in the mouse brain. Both single and repeated treatment with cyclosporine significantly facilitated the serotonin turnover as estimated from the probenecid-induced accumulation of 5-hydroxyindoleacetic acid, but either mode of treatment failed to change the contents of monoamines and their metabolites or the turnover of noradrenaline and dopamine. Therefore, the cyclosporine-enhanced activity of serotonin neurons may be interpreted as producing adverse central effects, including tremors.

Neurodevelopmental outcome of young children with extrahepatic biliary atresia 1 year after liver transplantation

STUDY DESIGN

Forty children < 2 years of age receiving extrahepatic liver transplantation were tested with the Bayley Scales of Infant Development before transplantation and again at 3 and 12 months after transplantation. Neurodevelopmental status 1 year after transplantation was organized by a descriptive statistic of normal, suspect, or delayed. Disease and transplantation variables were investigated for association with delayed neurodevelopmental outcome.

RESULTS

Before transplantation mental development was in the low-average range (92 +/- 13.2) with psychomotor development 1 SD below the norm (82.5 +/- 13). Three months after transplantation both mental (80.1 +/- 12.6) and psychomotor (69 +/- 16.1) scores dropped 1 SD, but 1 year after transplantation mental and psychomotor scores recovered to the pretransplantation level of functioning. One year after transplantation 35% of the study group was diagnosed as developmentally delayed. Delayed development was associated with decreased weight (p < 0.04), low albumin (p < 0.02), length of hospital stay (p < 0.04), and age at transplantation (p < 0.05).

CONCLUSION

Young children undergoing liver transplantation are at risk for developmental delay. Aggressive nutritional support before transplantation and timing of transplantation before malnutrition develops may reduce developmental delays.

Watershed imaging features and clinical vascular injury in cyclosporin A neurotoxicity

PURPOSE

The purpose of our study was to assess whether the imaging and clinical features of cyclosporin A (CsA) neurotoxicity support a vascular "watershed" cause for the brain lesions observed.

METHOD

Fourteen patients receiving CsA after allogeneic bone marrow transplantation or with marrow aplastic disorders developed neurotoxicity and MR or CT imaging abnormalities. The locations of brain lesions were analyzed, and clinical features, in particular bone marrow transplant thrombotic microangiopathy (BMT-TM), were assessed.

RESULTS

Sixty-six lesions had consistent locations in watershed zones between major cerebral vessels or their main branches, including the parietal area (19), occipital poles (18), frontoparietal junction (15), inferior temporooccipital junction (10), and cerebellum (3). BMT-TM was identified in 10 of 10 marrow transplant patients studied.

CONCLUSION

Vascular injury, suggested from watershed location and BMT-TM, likely establishes the location of the brain lesions in CsA neurotoxicity. Secondary toxicity in these vulnerable regions may cause the white matter lesions.

Differences in lipoprotein lipid concentration and composition modify the plasma distribution of cyclosporine

PURPOSE

The purpose of this study was to define the relationship between lipoprotein (LP) lipid concentration and composition and the distribution of cyclosporine (CSA) in human plasma.

METHODS

3H-CSA LP distribution was determined in normolipidemic human plasma that had been separated into different LP and lipoprotein-deficient plasma (LPDP) fractions by either affinity chromatography coupled with ultracentrifugation, density gradient ultracentrifugation or fast protein liquid chromatography. 3H-CSA LP distribution (at a concentration of 1000 ng/ml) was also determined in patient plasma samples with defined dyslipidemias. Furthermore, 3H-CSA LP distribution was determined in patient plasma samples of varying LP lipid concentrations. Following incubation, the plasma samples were separated into their LP and LPDP fractions by sequential phosphotungistic acid precipitation in the dyslipidemia studies and by density gradient ultracentrifugation in the specific lipid profile studies and assayed for CSA by radioactivity. Total plasma and lipoprotein cholesterol (TC), triglyceride (TG) and protein (TP) concentrations in each sample were determined by enzymatic assays.

RESULTS

When the LP distribution of CSA was determined using three different LP separation techniques, the percent of CSA recovered in the LP-rich fraction was greater than 90% and the LP binding profiles were similar with most of the drug bound to plasma high-density (HDL) and low-density (LDL) lipoproteins. When 3H-CSA was incubated in dyslipidemic human plasma or specific patient plasma of varying LP lipid concentrations the following relationships were observed. As the very low-density (VLDL) and LDL cholesterol and triglyceride concentrations increased, the percent of CSA recovered within the VLDL and LDL fractions increased. The percent of CSA recovered within the HDL fraction significantly decreased as HDL triglyceride concentrations increased. The percent of CSA recovered in the LPDP fraction remained constant except in hypercholesterolemic/hypertriglyceridemic plasma where the percent of CSA recovered decreased. Furthermore, increases in VLDL and HDL TG/TC ratio resulted in a greater percentage of CSA recovered in VLDL but less in HDL.

CONCLUSIONS

These findings suggest that changes in the total and plasma LP lipid concentration and composition influence the LP binding of CSA and may explain differences in the pharmacological activity and toxicity of CSA when administered to patients with different lipid profiles.

Neuropsychiatric side effects of FK506 vs. cyclosporine A. First-week postoperative findings

The authors studied 31 liver transplant patients to compare neuropsychiatric side effects of a newer immunosuppressant, FK506, to cyclosporine A (CYA). Patients were randomly assigned to either FK506 or CYA. At the 1-week postoperative stage, cognitive status was assessed with the Mini-Mental State Exam, Trailmaking Tests (TMT) A and B, Delirium Rating Scale, and a neuropsychiatric symptom checklist. No statistically significant differences were found on any outcome variable between these two drugs, though scores on the TMTs were impaired as compared with published norms. The FK506 patients had moderately impaired TMT scores, whereas the CYA patients had only mild impairment. The patients demonstrate good cognitive recovery at 1 week post-transplantation, with only mild evidence of cognitive impairment.

Central nervous system disorders after renal transplantation in cats

OBJECTIVE

This study describes the incidence and severity of postoperative central nervous system (pCNS) disorders in feline renal transplant recipients.

STUDY DESIGN

A retrospective study based on the medical records of cats that received renal allografts from 1987 to 1996.

ANIMALS OR SAMPLE POPULATION

Fifty-seven client-owned cats received renal allografts for the treatment of renal failure.

METHODS

The frequency, duration, severity, and treatment of episodes of pCNS disorders were recorded from the medical records.

RESULTS

Twelve (21%) of 57 cats had pCNS disorders 1 hour to 5 days after the surgical procedure. Seven cats survived; four had single or multiple seizure episodes, and two had seizure episodes or disorientation followed by a period of coma. One cat became temporarily ataxic and blind after restraint for venipuncture. Five cats died; all had episodes of disorientation or seizures, or both, that progressed to a nonrecoverable comatose state, respiratory arrest or cardiac arrest, or both. There were no significant differences between the two groups in preoperative serum creatinine, blood urea nitrogen, or cholesterol levels, and intraoperative blood pressure measurements. There were no significant differences in the postoperative serum glucose levels, electrolytes levels, or osmolality between the two groups. The cats with pCNS disorders had a mean preoperative trough cyclosporine A (CyA) whole blood level of 429 ng/mL; cats without pCNS disorders had a significantly (P = .0116) higher mean preoperative trough CyA whole blood level of 736 ng/mL.

CONCLUSION

Central nervous system disorders are a common and often fatal complication of renal transplantation in cats.

CLINICAL RELEVANCE

Recognition of pCNS disorders, and possible causes, will help develop hypotheses to investigate the problem.

Evaluation of surgical scrub methods for large animal surgeons

OBJECTIVE

The objective of this study was to determine the effectiveness of a 5-minute surgical scrub using either a one-brush or a two-brush technique in clean and dirty surgical procedures, and to compare the efficacy of povidone iodine with chlorhexidine as surgical scrub solutions.

STUDY DESIGN

Prospective clinical trial.

METHODS

Nine veterinarians scrubbed their hands on eight separate occasions using either povidone iodine or chlorhexidine gluconate. A 5-minute scrub and either a one-brush or two-brush technique used in both clean and dirty operations were evaluated by taking glove juice samples before scrubbing, immediately after scrubbing, and 30, 60, 90, and 120 minutes after scrubbing. Glove juice samples were cultured and the colonies were counted. Percent reductions of bacterial forming units were calculated for all eight scrub procedures.

RESULTS

All scrub procedures provided an adequate percent reduction in colony forming units (CFU) during the 2-hour sampling period. The number of CFU immediately after scrubbing were significantly lower than prescrub. At 120 minutes, there were significantly fewer CFUs than presecrub, but there were more than immediately after scrubbing. No significant difference in reduction in CFUs were detected between one-brush and two-brush techniques. Both chlorhexidine and povidone iodine scrub solutions adequately reduced bacterial colony counts for 120 minutes after scrubbing regardless of the amount of contamination before skin preparation.

CONCLUSIONS

Bacterial counts after a hand scrub procedure using a one-brush technique were not significantly different than after a procedure that used a two-brush technique. Povidone iodine and chlorhexidine are equally effectively in decreasing bacterial numbers on the skin, given a variety of contamination levels present before the scrub procedure.

CLINICAL RELEVANCE

Surgeons may use either chlorhexidine or povidone iodine for antiseptic preparation of their hands before surgery. A two-brush technique is not necessary.

Survival of rat and porcine Sertoli cell transplants in the rat striatum without cyclosporine-A immunosuppression

The use of cyclosporine-A (CsA) immunosuppression for neural transplantation has become the treatment of choice for ameliorating host-graft rejection responses in human and animal transplant studies. However, the cytotoxic effects of CsA have warranted a search for alternative methods of protecting neural transplants. Sertoli cells produce an immunosuppressant factor, Fas ligand (Fas-L), that may provide the testis with its immunoprivileged status. Therefore, it has recently been suggested that these cells may be useful in producing localized immunosuppression for transplants. If Sertoli cells do produce localized immunosuppression, then it should be possible to successfully transplant Sertoli cells without additional immunosuppression following transplant surgery. The present study was undertaken to determine whether rat or porcine Sertoli cells transplanted into rat brain would survive for an extended period of time without CsA immunosuppression. Isolated rat or porcine Sertoli cells prelabeled with DiI were transplanted into normal rat brain. We report that both rat Sertoli cell allografts and porcine Sertoli cell xenografts survived for at least 2 months posttransplantation into the rat brain without CsA immunosuppression, indicating that these grafts were capable of producing sufficient localized immunosuppression to survive at the site of transplant without additional systemic immunosuppression.

Reversible posterior leukoencephalopathy following organ transplantation. Description of two cases

Although neurologic changes after organ transplantation are often secondary to opportunistic infections or vascular insults, new pathological entities are emerging. We have recently encountered two patients who, a few days after liver and heart transplant, respectively, developed neurological signs and symptoms. Head computerized tomography (CT) scan showed nonenhancing areas of low attenuation, and magnetic resonance imaging (MRI) demonstrated multiple areas of increased signal intensity in the subcortical white matter on T2-weighted images. Stereotactic biopsy of the intracranial lesions was performed in one case. Light microscopic examination demonstrated only mildly edematous white matter. No infectious organisms were observed on light or electron microscopy. In one patient, follow-up MRI 3 months later showed almost complete resolution of the signal abnormalities. Both patients' clinical condition progressively improved. The neuroradiological abnormalities described are consistent with the 'reversible posterior leukoencephalopathy' syndrome associated with cyclosporine toxicity. The pathophysiology of these lesions is unclear; however, it has been suggested that cyclosporine causes an acute ischemic insult secondary to vascular spasm with resultant axonal swelling. This hypothesis is supported by the hypoattenuation seen on CT, the prolonged T2 relaxation seen on MRI, and the absence of contrast enhancement. Concomitant factors (such as hypocholesterolemia or associated therapy with high dose steroids) are important in the development of these lesions as in both of our patients cyclosporine levels were in the normal range. Fortunately, these lesions and the associated manifestations are most often reversible and regress with adjustments of cyclosporine dosage and/or correction of concomitant facilitating factors.

Nonpulmonary medical complications in the intermediate and long-term survivor

This article deals with the nonpulmonary, non-infectious complications in intermediate and long-term survivors of lung transplantation. Although they are an infrequent cause of mortality, these disorders can cause significant morbidity in this population. Diseases associated with the gamut of medications used post-transplant are specifically discussed, as are diseases caused by the direct immunosuppressive action of some of these drugs. General care of transplant patients also entails attention to their underlying diseases, and to routine medical considerations common to all patients.

Safety of corticosteroids and immunosuppressive agents in ulcerative colitis

For many years, corticosteroids have been the mainstay for treating acute ulcerative colitis. In patients with refractory disease, immunosuppressive therapy may be indicated, including azathioprine or its metabolite 6-mercaptopurine, cyclosporin and possibly methotrexate. Their benefits in ulcerative colitis must be weighed up against their possible adverse effects, the availability of surgical cure for this condition, and the long-term risk of carcinoma complicating colitis that applies in patients with chronic extensive disease. Information about the safety of corticosteroids and immunosuppressive agents has accumulated as a result of their extensive use in inflammatory bowel disease, organ transplantation and various other disorders.

Cyclosporin inhibits hyperalgesia and edema in arthritic rats: role of the central nervous system

Since arthritis induced by Mycobacterium products (adjuvant) in rats is considered to be immunologically driven, the objective of the present study was to determine if the immunosuppressor drug cyclosporin could affect hindpaw edema and joint hyperalgesia simultaneously. Female Holtzman rats (140-170 g) presented hyperalgesia and edema on the 8th and 12th day following adjuvant injection. Daily systemic (oral or intramuscular) administration of cyclosporin (0.5-5.0 mg kg (-1) day (-1)) or dexamethasone (0.01-0.1 mg kg (-1) day (-1)) for 15 days starting on day zero dose-dependently inhibited the hindpaw edema and hyperalgesia in arthritic rats. However, hyperalgesia but not edema could be detected two days after cyclosporin withdrawal. We concluded that a) the continuous presence of cyclosporin is essential to reduce the development of joint hyperalgesia and that b) different mechanisms underlie the appearance of hyperalgesia and edema in this model. The intracerebroventricular (i.c.v.) administration of 5-50-fold smaller doses of cyclosporin (1.5-150 micrograms/day) or dexamethasone (15 micrograms/day) also reduced the arthritic hindpaw edema and hyperalgesia. Peripheral blood from animals injected with effective systemic cyclosporin doses showed detectable levels of the drug, whereas peripheral blood from those injected with i.c.v. cyclosporin did not, as measured by specific RIA. Our results indicate that cyclosporin administered by the central route is as effective as by the systemic route to reduce joint hyperalgesia and hindpaw edema in arthritic rats. The antiarthritic effect induced by low doses of cyclosporin in the central nervous system (CNS) could be explored to avoid it often associated systemic side effects during chronic therapy. However, the mechanism(s) involved in the antiarthritic response to cyclosporin in the CNS remain to be elucidated.

A microemulsion of cyclosporine without intravenous cyclosporine in liver transplantation

A microemulsion formulation of cyclosporine (CsA) has improved absorption compared with the original form. The purpose of this case control study was to assess the safety and efficacy of the microemulsion without intravenous CsA for induction immunosuppression in adult liver transplantation. Twenty-one consecutive patients receiving induction immunosuppression with the microemulsion 15 mg/kg/day were compared with 20 patients receiving intravenous CsA and the original oral form. Both groups received the same dose of methylprednisilone. Twenty of 21 patients receiving the microemulsion required no intravenous CsA to achieve target CsA levels. All patients receiving the original form received initial intravenous CsA. There was no difference in trough CsA levels between the two groups at 24 and 48 hours. The microemulsion group had 24 hr and 48 hr trough CsA levels of 227+/-15 and 520+/-300 ng/ml by monoclonal RIA while the intravenous CsA group had 24 and 48 hr trough levels of 293+/-18 and 405+/-91 ng/ml. CsA levels analyzed by HPLC were 20% lower than by RIA. The frequency of adverse events resulting in reduction of drug dosage was similar for the microemulsion and the original form: neurotoxicity (23 vs. 40%, P=.30); nephrotoxicity (25 vs. 45%, P=.32), and no patients required dialysis. There was no difference in septic complications. One patient required discontinuation of the microemulsion in an attempt to reverse severe neurotoxicity. A total of 75% of microemulsion patients were rejection free at 3 months while only 35% of CsA patients remained rejection free (P=0.02). These data suggest that the use of the microemulsion without intravenous CsA in liver transplantation is safe and efficacious, and may result in decreased episodes of acute rejection.

Testis-derived Sertoli cells survive and provide localized immunoprotection for xenografts in rat brain

Transplantation of neural tissue into the mammalian central nervous system has become an alternative treatment for neurodegenerative disorders such as Parkinson's disease. Logistical and ethical problems in the clinical use of human fetal neural grafts as a source of dopamine for Parkinson's disease patients has hastened a search for successful ways to use animal dopaminergic cells for human transplantation. The present study demonstrates that transplanted testis-derived Sertoli cells into adult rat brains survive. Furthermore, when cotransplanted with bovine adrenal chromaffin cells (xenograft), Sertoli cells produce localized immunoprotection, suppress microglial response and allow the bovine cells to survive in the rat brain without continuous systemic immunosuppressive drugs. These novel features support Sertoli cells as a viable graft source for facilitating the use of xenotransplantation for Parkinson's disease and suggest their use as facilitators, (i.e., localized immunosuppression) for cell transplantation in general.

Changes in trough levels of whole blood cyclosporine and graft function of a kidney transplant recipient with onset of hypothyroidism after transplantation

The immunosuppressive and toxic effects of cyclosporine (CsA) are affected by many factors. We present the first case of a kidney transplant patient who had an onset of hypothyroidism about two months after the transplantation. In this case, trough levels of whole blood CsA and total serum cholesterol levels increased at the same time. But the decrease in renal function was not as severe as expected from the very high trough levels of whole blood CsA. Elevation of the trough level of whole blood CsA may be due to a decrease in CsA clearance resulting from the decreased cytochrome P-450 activity in hypothyroidism. Furthermore, a decrease in thyroid hormone level and increase in plasma lipoprotein level might have affected the distribution of CsA, and this change might have influenced the toxic effect of CsA In conclusion, our case suggests that thyroid function and plasma lipoprotein level should be considered important factors that affect the pharmacokinetics and action of CsA.

Evaluation of the effects of immunosuppressants on neuronal and glial cells in vitro by multinuclear magnetic resonance spectroscopy

The use of the undecapeptide cyclosporine and the macrolide tacrolimus as immunosuppressants in transplantation medicine and for the therapy of immune diseases often provokes side effects, among the most important one is neurotoxicity. Changes in the cellular metabolism of glial cells (C6 rat glioma), neuronal cells (N1E-115 mouse neuroblastoma) and primary glia cells (isolated from rats) after addition of cyclosporine and tacrolimus were investigated using 1H-, 13C- and 31P-NMR spectroscopy in vitro. Cells were exposed to various concentrations of the drugs from 3 h to 42 days. The immunosuppressants (cyclosporine IC50 : 55 mumol/l; tacrolimus IC50 : 47 mumol/l) inhibited cell proliferation in a concentration- and time-dependent fashion. Multinuclear NMR studies of PCA extracts of drug-treated cells showed a significant deterioration in the energy status (a decreasing level of PCr : -46 +/- 11%; an increasing NDP/NTP ratio: +136 +/- 4% and an increasing level of Pi : +248 +/- 15%; mean +/- standard deviation). It also showed decreasing concentrations of major cell metabolites like NAA (-59 +/- 12%) in neuroblastoma cells and myo-inositol (-47 +/- 6%) in glia cells compared with untreated controls. Immunosuppressive treatment caused a large reduction of taurine (-36 +/- 12%) and glutamate (-68 +/- 10%) in all cell cultures, whereas intermediates of phospholipid biosynthesis (PE: +59 +/- 13%; PC: +127 +/- 27%;) and breakdown (GPE: +215 +/- 24%; GPC: +245 +/- 17%) increased. No significant differences were observed between the two immunosuppressants. The toxic effects of immunosuppressants on cell cultures are in line with MRI studies of brain oedema observed in patients under immunosuppressive treatment.

Neurophysiologic evaluation of cyclosporine toxicity associated with bone marrow transplantation

INTRODUCTION

Cortical blindness, a rare form of cyclosporine (CSA) neurotoxicity, has previously been described in only nine bone marrow transplant (BMT) recipients.

METHODS

Our institution averages 35 allogeneic BMT's per year. In the past year we have seen two women with reversible cortical blindness secondary to CSA toxicity.

RESULTS

Age (years) (Case 1; Case 2): 32; 22. Day post-BMT: 41; 50. Peak CSA level (ng/ml): 1159; 632. Both had a history of renal toxicity requiring adjustment of CSA dosage. MRI - both with diffuse while matter changes. EEG - both with moderate to severe generalized slowing. Visual evoked potentials were markedly prolonged in both. Auditory evoked potentials: minimally abnormal; normal. Somatosensory evoked potentials - both normal. Prompt improvement occurred with discontinuation of CSA. Followup neurophysiologic evaluations were normal, however structural changes remained on MRI.

CONCLUSION

As neurophysiologic studies closely follow the clinical status they should be included in the evaluation and followup of CSA neurotoxicity.

Cyclosporine induces neuronal apoptosis and selective oligodendrocyte death in cortical cultures

Cyclosporine is used clinically as an immunosuppressant, but carries a risk of central nervous system toxicity due to undefined mechanisms. We examined the ability of cyclosporine exposure to kill cultured mouse cortical neurons and glia. Mixed neuron/glial cultures exposed to 1 to 20 microM cyclosporine for 24 to 48 hours developed concentration-dependent neuronal death, with most neurons destroyed by 20 microM cyclosporine. This neuronal death was characterized by cell body shrinkage and blebbing, chromatin condensation, and internucleosomal DNA fragmentation, consistent with apoptosis. Neuronal death was reduced by addition of cycloheximide, brain-derived neurotrophic factor, or insulin-like growth factor I but not N-methyl-D-aspartate- or AMPA-type glutamate receptor antagonists. Oligodendrocytes were more sensitive to cyclosporine-induced damage than were neurons, but astrocytes were relatively resistant. Oligodendrocyte death was accompanied by positive TUNEL (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end-labeling) staining and was attenuated by application of ciliary neurotrophic factor or insulin-like growth factor I but not glutamate receptor antagonists. Present observations raise the possibility that the central nervous system toxicity syndrome associated with cyclosporine may be caused by the drug-induced death of oligodendrocytes and neurons.