Open-label comparison of the antiemetic efficacy of single intravenous doses of dolasetron mesylate in pediatric cancer patients receiving moderately to highly emetogenic chemotherapy.

BACKGROUND: Nausea and vomiting are among the most unpleasant adverse side effects of cancer therapy. PROCEDURE: An open-label dose-escalation study was conducted to assess the appropriate intravenous dose of dolasetron for pediatric patients undergoing chemotherapy. Patients received dolasetron in single intravenous doses of 0.6 (n = 10), 1.2 (n = 12), 1.8 (n = 12), or 2.4 (n = 12) mg/kg 30 min before receiving emetogenic chemotherapy. Pharmacokinetic parameters were evaluated at each dose level and efficacy was evaluated over the first 24 hr following the administration of dolasetron. RESULTS: A complete response was achieved in 10% of patients given 0.6 mg/kg, 25% of patients given 1. 2 mg/kg, 67% of patients given 1.8 mg/kg, and 33% of patients given 2.4 mg/kg. Peak plasma concentrations (Cmax) were observed between 0. 33 and 0.75 hr following dolasetron infusion. Cmax and area under plasma concentration-time (AUC) increased with larger doses of dolasetron, while terminal disposition half-life (t1/2) and apparent clearance (Clapp) were not significantly changed with respect to dose. For 1.8-mg/kg dolasetron, the t1/2 was 4.98 hr and the maximum plasma concentration (tmax) 0.47 hr. Adverse events were mild to moderate. No serious events occurred. Conclusions. This study suggests that a single intravenous dose of 1.8 mg/kg is the optimum single intravenous dose for controlling chemotherapy-induced emesis in pediatric patients.

Intrathecal leucovorin after intrathecal methotrexate overdose.

PURPOSE: Intrathecal methotrexate is a standard and important therapy in acute leukemia. Unfortunately, overdose is a well reported complication of this therapy. We report a fatal event secondary to intrathecal leucovorin. PATIENTS, METHODS, AND RESULTS: An 11-year-old boy with a 6-month history of treatment of acute lymphocytic leukemia received an "overdose" of 20 mg of intrathecal methotrexate. He was treated with intrathecal leucovorin and subsequently experienced severe neurotoxicity and died. This was attributed to the use of intrathecal leucovorin, the first such case reported in the medical literature. CONCLUSION: A review of the literature indicates that a careful definition of overdose needs to be applied in cases of intrathecal methotrexate: those <100 mg need less intervention, >500 mg will not respond to any intervention, and the middle group, 100-500 mg, can be treated with a variety of approaches, which are outlined. The standard treatment includes the use of ventriculolumbar washout, CSF exchange, or intravenous pharmacotherapy with leucovorin. Recently, the use of carboxypeptidase has been under investigation. All clinicians who administer intrathecal medications should be aware of these complications and the appropriate treatments of them (including rescue). Leucovorin should not be given intrathecally.

Cranial nerve palsy in childhood acute lymphoblastic leukemia and non-Hodgkin's lymphoma.

Forty-five children with acute lymphoblastic leukemia or non-Hodgkin's lymphoma had cranial nerve palsy (CNP) as a complication of their disease. Twenty-two of these children had CNP initially and 23, at relapse, with or without previous hematologic relapse. Only one of the 23 patients with CNP at relapse was a long-term survivor. In contrast, 11 of the 22 children who had CNP initially survived in remission for 3+ months to 13+ years. Two factors are associated with an improved outcome for patients with CNP at diagnosis: treatment after 1979 (P less than 0.004) and male gender (P less than 0.01). Patients who received radiation therapy fared better than those for whom radiation was not given (disease-free survival at 2 years 53% versus 29%). The authors conclude that CNP signifies an aggressive or advanced disease requiring intensive systemic chemotherapy and that the role of irradiation should be examined for this group of patients.

Malignant hepatic tumours in children: incidence, clinical features and aetiology.

Congenital defects and other disorders have been reported in association with malignant liver tumours. In order to assess their significance, a population-based survey was undertaken on children aged less than 15 years diagnosed with malignant liver tumours during the 30 years 1957-1986. The cases were identified from information collected by the West Midlands Regional Children's Tumour Registry. Pertinent data were extracted from their clinical records, and the original biopsy and any necropsy material were reviewed by a panel of three paediatric pathologists. Of the 50 eligible cases registered, eight were excluded because histology review showed that they had non-malignant conditions (3) or malignancies of extrahepatic origin (4) or because no pathological material was available (1). The diagnoses in the remaining 42 cases were hepatoblastoma (27), hepatocellular carcinoma (3), rhabdomyosarcoma (6), rhabdoid tumour (3) and yolk sac tumour (3). The incidence of primary malignant liver tumours was 1.20 per 10(6) person years and that of the hepatoblastoma sub-group was 0.77 (average childhood population of the West Midlands for the time period being 1,166,500). The presenting clinical, radiological and biochemical features were similar to those reported in other series and the ethnic and social class distributions were unremarkable compared with the local population. Congenital defects or other possibly related features were present in nine (21%) patients. Our results, taken with other reports, suggest that hepatoblastoma is a malignant tumour related to maldevelopment, possibly associated with 11p or 5q mutations, whereas hepatocellular carcinoma is more usually a complication of metabolic and other disorders which lead to cirrhosis.

Deoxyribonucleic acid-deoxyribonucleic acid hybridization of R factors.

A new method of estimating deoxyribonucleic acid homology is presented and used to measure the homology between bacterial plasmids of different compatibility groups. Deoxyribonucleic acid of the P-group plasmid RP1, originally isolated in Pseudomonas aeruginosa, has considerable (50%) homology with an N-group plasmid of the Enterobacteriaceae.

Molecular characterization of the R factors implicated in the carbenicillin resistance of a sequence of Pseudomonas aeruginosa strains isolated from burns.

An outbreak of R-factor-mediated carbenicillin resistance in Pseudomonas aeruginosa in burned patients in March 1969 was followed by a second outbreak 6 months later. No R-factor-carrying P. aeruginosa strains were detected in the intervening period but R-factor-determined lactamase was commonly encountered, particularly in Klebsiella aerogenes strains. A comparison of the molecular properties of the R factors in pseudomonads from the first and second phases with those in the Klebsiella strains from the intervening period showed them to be very closely related. A single R-factor type therefore may have been maintained in the Burns Unit between the two Pseudomonas outbreaks as a plasmid conferring resistance to ampicillin in K. aerogenes.

Mutations in R factors of Escherichia coli causing an increased number of R-factor copies per chromosome.

A mutant of the repressed R factor R1a and two mutants of the derepressed R factor R1drd-19 showing a two- to fourfold increase in resistance to all of the antibiotics to which the wild-type R factors mediate resistance were studied. The increased resistance was due to a two- to fourfold increase in the number of R-factor copies per chromosome. The production of drug-metabolizing enzymes was linearly correlated to the gene dosage. There was also a linear correlation between resistance to the drugs and the production of the corresponding enzymes. The mutations were also expressed in Proteus mirabilis PM1. In Proteus, R factors are split into two plasmids, resistance transfer factor and the resistance part. The mutation in one of the mutant R factors seems to be located in the resistance part. A second fi(+) R factor (R100) was introduced into strains already carrying R1drd-19 or the mutant R factor R1drd-19B2. In the first case, R100 and R1drd-19 segregated with equal probability when the bacteria were grown on antibiotic-free medium, whereas, in the second case, R100 was rapidly and preferentially excluded.

Properties of a R factor which originated in Pseudomonas aeruginosa 1822.

RP1, a group of genes specifying resistance to carbenicillin, neomycin, kanamycin, and tetracycline and originating in a strain of Pseudomonas aeruginosa, was freely transmissible between strains of P. aeruginosa, Escherichia coli, and Proteus mirabilis. Acquisition of the multiple drug resistance specified by RP1 by these strains was accompanied by acquisition of an extrachromosomal satellite of covalently closed circular deoxyribonucleic acid of molecular weight about 40 million daltons and of buoyant density 1.719 g/cm(3) (60% guanine plus cytosine).