Population based MRI and DTI templates of the adult ferret brain and tools for voxelwise analysis.

Non-invasive imaging has the potential to play a crucial role in the characterization and translation of experimental animal models to investigate human brain development and disorders, especially when employed to study animal models that more accurately represent features of human neuroanatomy. The purpose of this study was to build and make available MRI and DTI templates and analysis tools for the ferret brain as the ferret is a well-suited species for pre-clinical MRI studies with folded cortical surface, relatively high white matter volume and body dimensions that allow imaging with pre-clinical MRI scanners. Four ferret brain templates were built in this study - in-vivo MRI and DTI and ex-vivo MRI and DTI - using brain images across many ferrets and region of interest (ROI) masks corresponding to established ferret neuroanatomy were generated by semi-automatic and manual segmentation. The templates and ROI masks were used to create a web-based ferret brain viewing software for browsing the MRI and DTI volumes with annotations based on the ROI masks. A second objective of this study was to provide a careful description of the imaging methods used for acquisition, processing, registration and template building and to demonstrate several voxelwise analysis methods including Jacobian analysis of morphometry differences between the female and male brain and bias-free identification of DTI abnormalities in an injured ferret brain. The templates, tools and methodological optimization presented in this study are intended to advance non-invasive imaging approaches for human-similar animal species that will enable the use of pre-clinical MRI studies for understanding and treating brain disorders.

Characterisation of a novel high-purity, double virus inactivated von Willebrand Factor and Factor VIII concentrate (Wilate).

This study summarises the biochemical and functional properties of a new generation plasma-derived, double virus inactivated von Willebrand Factor/Factor VIII (VWF/FVIII) concentrate, Wilate, targeted for the treatment of both von Willebrand disease (VWD) and haemophilia A. The manufacturing process comprises two chromatographic steps based on different performance principles, ensuring a high purity of the concentrate (mean specific activity in 15 consecutive production batches: 122 IU FVIII:C/mg total protein) and, thus, minimising the administered protein load to the patient (specification: < or = 15 mg total protein per 900 IU Wilate). The optimised solvent/detergent (S/D) treatment and prolonged terminal dry-heat (PermaHeat) treatment of the lyophilised product at a specified residual moisture (RM) provide two mechanistically independent, effective and robust virus inactivation procedures for enveloped viruses and one step for non-enveloped viruses. These process steps are aggressive enough to inactivate viruses efficiently, but yet gentle enough to maintain the structural integrity and function of the VWF and FVIII molecules, as proven by state-of-the-art assays covering the diverse features of importance. The VWF multimeric pattern is close to the one displayed by normal plasma, with a consistent content of more than 10 multimers, but a relatively lower portion of the very high multimers. The multimeric triplet structure is normal, underlining the gentle and effective manufacturing process, which does not require the addition of protein stabilisers at any step. The balanced activity ratio of VWF to FVIII is close to that of plasma from healthy subjects, rendering Wilate suitable also for the safe and effective treatment of patients with VWD.

Clinical use of topoisomerase I inhibitors in anticancer treatment.

The camptothecin analogs topotecan and irinotecan have shown to be among the most effective anticancer agents and, as S-phase specific agents, their antitumor effect is maximized when they are administered in protracted schedules. The documented activity as single agents in many adult and pediatric malignancies has been followed by their use in combination with other anticancer agents. These studies have shown promising results, and have placed topotecan and irinotecan in the first line treatment for some malignancies. However, studies to better determine the optimal schedules and sequence of combinations are needed.

Treatment of childhood acute myelogenous leukemia with an intensive regimen (AML-87) that individualizes etoposide and cytarabine dosages: short- and long-term effects.

The purpose of this study was to assess the feasibility and efficacy of a treatment regimen for pediatric acute myelogenous leukemia (AML) that uses four rotating drug pairs and adjusts dosages of etoposide and cytarabine to target specific plasma concentrations. Thirty-one girls and 27 boys (median age, 9.7 years) with de novo AML were treated on the protocol. Six cycles of chemotherapy were planned. Cycles 1 to 4 comprised the drug combinations cytarabine plus etoposide, cytarabine plus daunomycin, etoposide plus amsacrine, and etoposide plus azacitidine, respectively. For cycles 5 and 6, the first two combinations were repeated. Dosages were adjusted to achieve plasma concentrations of 1.0 microM +/- 0.1 microM cytarabine and 30 microM +/- 0.3 microM etoposide. Forty-four patients (76%) entered complete remission. Of those, 24 have had relapses; 23 remain alive in first or subsequent remission. The 5-year event-free survival (EFS) estimate was 31.0% +/- 5.9%; the 5-year survival estimate was 41.4% +/- 6.3%. Six patients (10%) died of the toxic effects of therapy. Severe neutropenia occurred in all cycles. Long-term complications of therapy included hepatitis C, cardiac insufficiency, and hearing loss. Adjustment of cytarabine and etoposide dosage was feasible for achieving targeted plasma drug concentrations; however, the potential clinical efficacy of this approach was offset by substantial acute and long-term toxicity.

Population pharmacokinetics and pharmacodynamic modeling of abacavir (1592U89) from a dose-ranging, double-blind, randomized monotherapy trial with human immunodeficiency virus-infected subjects.

Abacavir (formerly 1592U89) is a carbocyclic nucleoside analog with potent anti-human immunodeficiency virus (anti-HIV) activity when administered alone or in combination with other antiretroviral agents. The population pharmacokinetics and pharmacodynamics of abacavir were investigated in 41 HIV type 1 (HIV-1)-infected, antiretroviral naive adults with baseline CD4(+) cell counts of >/=100/mm(3) and plasma HIV-1 RNA levels of >30,000 copies/ml. Data for analysis were obtained from patients who received randomized, blinded monotherapy with abacavir at 100, 300, or 600 mg twice-daily (BID) for up to 12 weeks. Plasma abacavir concentrations from sparse sampling were analyzed by standard population pharmacokinetic methods, and the effects of dose, combination therapy, gender, weight, and age on parameter estimates were investigated. Bayesian pharmacokinetic parameter estimates were calculated to determine the peak concentration of abacavir in plasma (C(max)) and the area under the concentration-time curve from time zero to infinity (AUC(0-infinity)) for individual subjects. The pharmacokinetics of abacavir were dose proportional over the 100- to 600-mg dose range and were unaffected by any covariates. No significant correlations were observed between the incidence of the five most common adverse events (headache, nausea, diarrhea, vomiting, and malaise or fatigue) and AUC(0-infinity). A significant correlation was observed between C(max) and nausea by categorical analysis (P = 0.019), but this was of borderline significance by logistic regression (odds ratio, 1.45; 95% confidence interval, 0.95 to 2.32). The log(10) time-averaged AUC(0-infinity) minus baseline (AAUCMB) values for HIV-1 RNA and CD4(+) cell count correlated significantly with C(max) and AUC(0-infinity), but with better model fits for AUC(0-infinity). The increase in AAUCMB values for CD4(+) cell count plateaued early for drug exposures that were associated with little change in AAUCMB values for plasma HIV-1 RNA. There was less than a 0.4 log(10) difference over 12 weeks in the HIV-1 RNA levels with the doubling of the abacavir AUC(0-infinity) from 300 to 600 mg BID dosing. In conclusion, pharmacodynamic modeling supports the selection of abacavir 300 mg twice-daily dosing.

Pharmacokinetics of irinotecan and its metabolites SN-38 and APC in children with recurrent solid tumors after protracted low-dose irinotecan.

Irinotecan (IRN), a topoisomerase I interactive agent, has significant antitumor activity in early Phase I studies in children with recurrent solid tumors. However, the disposition of IRN and its metabolites, SN-38 and APC, in children has not been reported. Children with solid tumors refractory to conventional therapy received IRN by a 1-h i.v. infusion at either 20, 24, or 29 mg/m2 daily for 5 consecutive days for 2 weeks. Serial blood samples were collected after doses 1 and 10 of the first course. IRN, SN-38, and APC lactone concentrations were determined by an isocratic high-performance liquid chromatography assay. A linear four-compartment model was fit simultaneously to the IRN, SN-38, and APC plasma concentration versus time data. Systemic clearance rate for IRN was 58.7 +/- 18.8 liters/h/m2 (mean +/- SD). The mean +/- SD ng/ml x h single-day lactone SN-38 area under the concentration-time curve (AUC(0-->6) was 90.9 +/- 96.4, 103.7 +/- 62.4, and 95.3 +/- 63.9 at IRN doses of 20, 24, and 29 mg/m2, respectively. The relative extent of IRN conversion to SN-38 and metabolism to APC measured after dose 1 were 0.49 +/- 0.33 and 0.29 +/- 0.17 (mean +/- SD). No statistically significant intrapatient difference was noted for SN-38 area under the concentration-time curve. Large interpatient variability in IRN and metabolite disposition was observed. The relative extent of conversion and the SN-38 systemic exposure achieved with this protracted schedule of administration were much greater than reported in adults or children receiving larger intermittent doses.

Phase I trial of a 96 h paclitaxel infusion with filgrastim support in refractory solid tumor patients.

A phase I study of a 96 h paclitaxel infusion with filgrastim support was performed to determine the toxicity, maximum-tolerated dose (MTD) and pharmacokinetics in patients with refractory solid tumors. In this phase I trial, the initial paclitaxel dose was 140 mg/m2/96 h followed by filgrastim (5 microg/kg/day s.c.) beginning 24 h after the paclitaxel and continued until granulocyte recovery. Cycles were repeated every 21 days. Patients with refractory solid tumors were eligible; however, only one previous chemotherapy regimen was allowed. The dose of paclitaxel was escalated by 20 mg/m2/96 h in subsequent cohorts until dose-limiting toxicity (DLT) occurred. Pharmacokinetic analysis was performed by quantitating paclitaxel concentrations at baseline, 24, 48, 72 and 96 h after the start of the paclitaxel infusion. Twenty-one patients were entered into this trial of which 19 were evaluable. A total of 52 treatment cycles were administered. DLT was seen in two of four patients at 200 mg/m2/96 h, and consisted of diarrhea, mucositis and granulocytopenic infection. The MTD of the 96 h paclitaxel infusion was 180 mg/m2 with filgrastim support. Mucosal and granulocyte toxicity were correlated with steady-state paclitaxel concentrations (Css) greater than 0.100 micromol/l. In the presence of liver function test 1.5 times or lower than normal, metastatic liver disease did not alter paclitaxel Css. Objective responses were observed in non-small cell lung cancer, small cell lung cancer and melanoma. The recommended phase II dose of paclitaxel infused over 96 h with filgrastim support is 180 mg/m2. Paclitaxel Css correlate with mucosal and granulocyte toxicity. In the presence of normal enzymatic function, metastatic liver disease does not affect paclitaxel clearance.

Collaboration between pharmacy and laboratory: defining total allowable error limits for therapeutically monitored drugs.

OBJECTIVE: To define the total allowable variability that is clinically tolerated for certain drug assays performed by the therapeutic drug monitoring (TDM) laboratory at our institution. METHODS: The monthly coefficient of variation (CV) for 13 of the most commonly performed drug assays was recorded for two concentrations: the upper and lower limits of the therapeutic range for each drug. A dosing simulation was performed for each drug by using population parameters to estimate the doses that would yield the two target concentrations in an adult patient. The smallest practical dosage adjustment that could be implemented in clinical practice was determined and the serum concentration resulting from this dosage change was estimated. Each change was equated to two standard deviations from the original drug concentration, and the corresponding CV or total allowable error (TEa) was calculated and compared with the laboratory's CV value. RESULTS: The laboratory CV was greater than the clinically defined TEa for amikacin at both trough and peak ranges, and for gentamicin and tobramycin at the trough range. Simulations for a patient with compromised renal function produced TEa values less than the reported CV for amikacin at both trough and peak ranges. Simulations for an obese patient produced TEa values less than the reported CV for amikacin, gentamicin, and tobramycin at both trough and peak ranges. The assay variability for these aminoglycosides is greater than the expected change in serum drug concentrations produced by the dosage changes used in the simulations. The TEa for all other drugs exceeded the laboratory CV, demonstrating assay variability within the clinically tolerated range. CONCLUSIONS: Knowledge of how the variability of a drug assay compares with its TEa allows clinicians to assess the usefulness of a serum drug concentration as a clinical tool.

General versus subpopulation values in Bayesian prediction of aminoglycoside pharmacokinetics in hematology-oncology patients.

The predictive performance of Bayesian estimates incorporating pharmacokinetic values for hematology-oncology patients was compared with that of Bayesian estimates incorporating general population values. In study phase 1, medical records were reviewed for 50 adult patients with a hematologic or oncologic diagnosis who had received i.v. gentamicin or tobramycin. Aminoglycoside pharmacokinetic values were calculated for the patients by using a modified two-point Sawchuk-Zaske method, and the subpopulation mean for each variable was determined. In phase 2, data for 10 other hematology-oncology patients receiving aminoglycosides were entered into the Abbottbase Bayesian pharmacokinetics program. Aminoglycoside pharmacokinetic values and serum concentrations for each of these 10 patients were estimated, first using the program's general population values and then repeating the analysis using the subpopulation means for volume of distribution and renal clearance slope obtained in phase 1. The serum aminoglycoside concentrations predicted by each Bayesian method were compared with the actual peaks and troughs. Both the peak and trough predictions of the Abbottbase program using the subpopulation values for volume of distribution and renal clearance slope were significantly less biased than those predicted by the Abbottbase program incorporating the general population values. The methods did not differ significantly in precision. Use of subpopulation pharmacokinetic values in Bayesian predictions of serum aminoglycoside concentrations in hematology-oncology patients reduced bias significantly but had no significant effect on precision.

The effect of post-operative instructions on recovery after tonsillectomy and adenoidectomy.

The effect of postoperative diet and activity instructions on the recovery rate after tonsillectomy and adenoidectomy (T & A) was assessed in 92 children ages 3 to 14 years. Two types of postoperative instruction were randomly assigned: 'Restricted', which advised limited, stay at home activities and a soft food liquid diet for 7-10 days, and 'nonrestricted', which advised return to activity and diet as tolerated by the child. Parental evaluation of the levels of pain, activity, and diet using an equal intervals scale was obtained. The number of doses of pain medication, the types of food eaten and postoperative complications were also recorded. No significant differences were found between the two groups in pain level, activity tolerance, return to normal diet, and numbers of doses of pain medication at day 3 and day 7 after surgery. More 'junk' food and spicy foods were eaten in the 'nonrestricted' group. Postoperative hemorrhage requiring intervention occurred in one child in each group. Implications for the children and their families undergoing T & A are discussed with attention to a review of the literature.