5-Fluorouracil-related severe toxicity: a comparison of different methods for the pretherapeutic detection of dihydropyrimidine dehydrogenase deficiency.

UNLABELLED: 5-Fluorouracil (5-FU)-related early toxicity, due to a metabolic deficiency, is rare but is potentially severe and even lethal (0.1%). It is due to dihydropyrimidine dehydrogenase (DPYD) gene polymorphism or some epigenetic factors. The detection of metabolic change could prevent severe toxicity, but until now it has not been carried out in clinical practice. PURPOSE: To find the simplest and most accurate pretherapeutic test to predict DPD deficiency in patients treated with 5-FU by comparing different approaches. RESULTS: Two hundred and fifty two French Caucasian patients treated by 5-FU infusion were studied. A two-step strategy, combining firstly SNP detection and uracil plasma measurement, followed, in cases where metabolic deficiency was suspected, by dihydrouracil/uracil ratio determination to confirm deficiency and to determine the optimum 5-FU dosage, appeared the best approach, with 83% and 82% sensitivity and specificity, respectively. CONCLUSION: These data support the future use of this approach, suitable to clinical practice, as screening test to identify DPD deficiency before 5-FU-based therapy.

A possible explanation for a neurotoxic effect of the anticancer agent oxaliplatin on neuronal voltage-gated sodium channels.

Oxaliplatin, a new widely used anticancer drug, displays frequent, sometimes severe, acute sensory neurotoxicity accompanied by neuromuscular signs that look like the symptoms observed in tetany and myotonia. The whole cell patch-clamp technique was employed to investigate the oxaliplatin effects on the electrophysiological properties of short-term cultured dorsal unpaired median (DUM) neurons isolated from the CNS of the cockroach Periplaneta americana. Within the clinical concentration range, oxaliplatin (40-500 microM), applied intracellularly, decreased the amplitude of the voltage-gated sodium current resulting in a reduction of half the amplitude of the action potential. For comparison, two other platinum derivatives, cisplatin and carboplatin, were found to be ineffective at reducing the sodium current amplitude. In addition, we compared the oxaliplatin action to those of its metabolites dichloro-diaminocyclohexane platinum (dach-Cl(2)-platin) and oxalate. Oxalate (500 microM) was found to be effective, like oxaliplatin, at reducing the inward sodium current amplitude, whereas dach-Cl(2)-platin (500 microM) failed to change the current amplitude. Interestingly, the effect of oxalate or oxaliplatin could be mimicked by using intracellularly applied 10 mM bis-(o-aminophenoxy)-N,N,N',N'-tetraacetic acid (BAPTA), known as chelator of calcium ions. We concluded that oxaliplatin was capable of altering the voltage-gated sodium channels through a pathway involving calcium ions probably immobilized by its metabolite oxalate. The medical interest of preventing acute neurotoxic side effects of oxaliplatin by infusing Ca(2+) and Mg(2+) is discussed.

[Uncontrolled retrospective study of 75 pregnancies in women treated for epilepsy]. / Etude rétrospective non contrôlée de 75 grossesses chez des femmes épileptiques traitées.

OBJECTIVE: Our purpose was to study pregnancies and birth outcomes in a population of women treated for epilepsy. STUDY DESIGN: A retrospective uncontrolled study of 75 pregnancies in 55 epileptic women under treatment was conducted in the nursery of CHU Angers. The course of pregnancies and deliveries, the frequency of congenital malformations and the clinical state of the neonates during the first 6 days of life were recorded. RESULTS: There was a high rate of prematurity (15%) especially in patients treated by phenobarbital, a 10.5% rate of intra-utero growth retardation, a 11% rate of major congenital malformations and a 9% rate of isolated minor congenital malformations. Congenital malformations were mainly facial dysmorphia, cardiopahties, urogenital tract abnormalities. The neonatal symptomatology was associated with a high level of antiepileptic drugs in neonates or to a withdrawal syndrome or to hypovitaminosis. CONCLUSION: Overall results justify implementing prevention and detection measures.

[Acute cardiac toxicity of 5-fluorouracil: pharmacokinetic correlation]. / Toxicité cardiaque aiguë du 5-fluorouracile: corrélation pharmacocinétique.

High-dose 5-fluorouracil (5-FU) continuous infusion over a 4-day period seems to dramatically increase the frequency of cardiac complications, which were however extremely rare in the past when it was injected in bolus form (1.6%). In order to evaluate their real incidence we looked for a relation between cardiac toxicity and clinical or 5 FU pharmacokinetic parameters. One hundred and thirty-three patients were followed up from January 1989 to March 1990, treated for head and neck, breast and colorectal cancers by high-dose 5-FU infusion (1,000 mg/sqm/d x 4 d) and cis-platinum (20 mg/sqm/d x 4 d). During each treatment course, daily electrocardiogram and 5 FU plasma assays were performed by high performance liquid chromatography, at 8 am and 8 pm. Twenty-eight patients presented 36 ischemic cardiac manifestations which were sometimes severe. Of these, 29 were asymptomatic. Cardiac toxicity frequency was not increased in the group treated for head and neck cancers. Pharmacokinetic analysis showed wide variations in 5-FU plasma levels in the 133 patients under study (from 20 to 1,200 ng/ml). Cardiac manifestations always appeared during the hours following very high 5-FU plasma levels (greater than 450 ng/ml). Cardiotoxicity seems to be linked to 5-FU plasma levels. Cis-platinum probably increases toxicity in this regimen. These findings indicate the advisability of a close follow-up by daily ECG when 5-FU is administered at high doses in continuous infusion and associated with cis-platinum. We are continuing to study 5 FU cardiac toxicity, especially in other regimens containing 5 FU and aim to evaluate the contribution of cardiac isotopic exams.

Acute renal failure following bone marrow transplantation: a retrospective study of 272 patients.

To assess the incidence, risk factors, and course of acute renal failure (ARF) following bone marrow transplantation (BMT), a retrospective analysis of 272 patients receiving transplants at the Fred Hutchinson Cancer Research Center during 1986 was undertaken. The patients were divided into three groups: group 1, hemodialysis requiring ARF; group 2, mild renal insufficiency (doubling of serum creatinine, Scr, but no dialysis); group 3, relatively normal post-BMT renal function (no doubling of Scr). Fifty-three percent of patients at least doubled their Scr (Groups 1 and 2), and 24% required dialysis. The degree of renal functional impairment had a dramatic impact on patient mortality rates (84%, 37%, and 17% in groups 1, 2, and 3, respectively). Jaundice (bilirubin greater than or equal to 2.0 mg/dL), weight gain (greater than or equal to 2.0 kg), amphotericin B use, and a pretransplant Scr greater than or equal to 0.7 mg/dL were independently associated with the subsequent development of dialysis-requiring ARF (P less than 0.001; relative risks, 3.0 to 7.7). Neither aminoglycoside/vancomycin/cyclosporine A use nor acute graft v host disease correlated with the development of ARF. A mismatched graft was a significant risk factor for ARF by univariate but not by multivariate analysis. Within 48 hours before doubling the Scr, 63% of group 1 patients had positive blood cultures and 39% developed hypotension. Of the 26 group 1 patients who had urine Na concentrations measured, 85% had values less than or equal to 40 mEq/L. Autopsy kidney specimens provided no clear explanation for ARF in the vast majority of patients in group 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Pathogenetic mechanisms in experimental hemoglobinuric acute renal failure.

To evaluate mechanisms in hemoglobinuric acute renal failure (ARF) rats were infused with hemoglobin under aciduric or alkalinuric conditions. Aciduric rats developed azotemia, distal heme casts, and proximal tubular cell (PTC) necrosis, whereas alkalinuric rats developed no renal damage. Aciduria converted hemoglobin to met-hemoglobin, which precipitated, forming distal casts and inducing ARF. Hematin formation was not observed. The importance of met-hemoglobin production was indicated by its greater toxicity than hemoglobin during aciduria and by its ability to induce ARF even under alkalinuric conditions. A link between obstructing casts and PTC necrosis was identified; tubular obstruction induced by various mechanisms (met-hemoglobin casts; ureteral ligation; ischemic ARF) increased PTC hemoglobin uptake, producing lysosomal overload (giant endolysosomes) and PTC necrosis. This worsened ischemic ARF despite an otherwise subtoxic hemoglobin dose being used that had no discernible acute renal vasoconstrictive effect. Iron chelation (deferoxamine)/hydroxyl radical scavenger (Na benzoate) therapy did not mitigate this exacerbation of ischemic injury, suggesting a nonoxidant mechanism. We conclude that H is nephrotoxic, particularly when intratubular obstruction facilitates PTC heme uptake. Thus aciduria-induced met-hemoglobin cast formation and concomitant ischemic renal injury predispose to its nephrotoxic effect.

Evidence against oxidant injury as a critical mediator of postischemic acute renal failure.

The purpose of this study is to confirm previous evidence for reactive oxygen species (ROS) as critical mediators of postischemic renal injury by documenting lipid peroxidation after ischemic-hypoxic insults and by demonstrating that antioxidants confer protection. Renal malondialdehyde (MDA) concentrations, an index of lipid peroxidation, were measured using uncorrected and tissue-chromagen-corrected methods in 1) cortical (C), outer medullary stripe (OMS), inner medullary (IM) whole renal tissues, and C and OMS mitochondria obtained 15 min after in vivo renal artery occlusion (RAO; x 45 min); 2) C, OMS, and IM whole tissues obtained 15 min after completing 45 min of ischemia in an isolated perfused kidney; and 3) isolated proximal tubular cell (PTC) suspensions after 45 min of hypoxia with 15 min of reoxygenation. Despite significant oxygen deprivation-induced injury in each of these systems, no significant rise in MDA concentrations could be documented, with the sole exception of the in vivo IM region (by uncorrected MDA assay only). The latter rise could be attributed to medullary vascular congestion causing a hemoglobin-induced artifact in the MDA assay. Sixty-minute in vivo RAO plus reflow also did not raise MDA. To validate the MDA assay 4.2 mM H2O2 was added to PTC. An abrupt fourfold rise in MDA resulted. Pretreatment of 30- and 45-min RAO rats with two antioxidants (allopurinol or superoxide dismutase) failed to confer functional or morphological protection. We conclude that ROS may not be critical consistent mediators of in vivo postischemic acute renal failure.

Degradation and resynthesis of adenine nucleotides in adult rat heart myocytes.

The degradation and short-term resynthesis of adenine nucleotides have been examined in a preparation of isolated rat heart myocytes. These myocyte preparations are essentially free of vascular and endothelial cells, contain levels of adenine nucleotides quite comparable to those of intact heart tissue, and retain these components remarkably well for up to 2 h of aerobic incubation in the presence of 1 mM Ca2+. When the cells are rapidly and synchronously de-energized by addition of uncoupler, an inhibitor of respiration and iodoacetate, cellular ATP is degraded almost quantitatively to AMP. The AMP is then converted to either intracellular adenosine, which accumulates to high concentrations before release to the cell exterior, or to IMP. The relative contribution of these two pathways depends on the metabolic state of the cells just prior to de-energization, with IMP production favored when respiring cells are de-energized and adenosine formation predominant when glycolyzing myocytes are subjected to this treatment. Cells de-energized by anaerobiosis in the absence of glucose lose ATP and adenine nucleotides with the production of IMP and adenosine. Upon reoxygenation, these cells restore a high adenylate energy charge and about 60% of control levels of GTP. There is a net resynthesis of 5-7 nmol of adenine nucleotides.mg-1 protein with a corresponding decline in IMP. Added [14C]adenosine labels the adenine nucleotide pool, but little net resynthesis of adenine nucleotides via adenosine kinase can be detected. It therefore appears that a rapid regeneration of adenine nucleotides can occur via the enzymes of the purine nucleotide cycle in heart myocytes and is limited by the size of the IMP pool retained.