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Biomedical subjects

E Dempsey

Publications and source records attributed to E Dempsey.

At least 19 recordsLinked to original sources
PubMed1999

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.

Adolescent↗
PubMed1998

Effects of altering the time of administration and the time frame of quality of life assessments in clinical trials: an example using the EORTC QLQ-C30 in a large anti-emetic trial.

Previous studies conducted by our group suggested that the ability to demonstrate an impact of emesis control on quality of life might depend upon when an quality of life instrument was administered in relation to chemotherapy and on the time frame of the questionnaire. This study was conducted to address this issue. Six hundred and fifty patients receiving moderately emetogenic chemotherapy in a randomized trial comparing a variety of anti-emetic regimens were allocated to four different modes of administration (days 4 and 8; 3 and 7 day time frames) of the QLQ-C30. Patients who completed the questionnaire at the time of maximal impact of chemotherapy (day 3) were more likely to report deterioration in quality of life. Patients who completed questionnaires at day 8 were more likely to report deterioration in quality of life if their questionnaire had a 7 day time frame rather than a 3 day time frame. Patients receiving more effective anti-emetic therapy had better quality of life. It was concluded that better anti-emetic control improves quality of life after moderately emetogenic chemotherapy. In studying quality of life in situations where the impact of treatment waxes and wanes, careful attention needs to be paid to scheduling the administration of questionnaires and to their time frame.

Adult↗
PubMed1997

The role of the 5-HT3 antagonists ondansetron and dolasetron in the control of delayed onset nausea and vomiting in patients receiving moderately emetogenic chemotherapy.

BACKGROUND: 5-HT3 antagonists are effective in reducing the acute nausea and vomiting caused by cancer chemotherapy. However, it is not clear whether continuing these agents beyond twenty four hours is useful in controlling emesis on days two to seven after chemotherapy. PATIENTS AND METHODS: Four hundred seven patients receiving moderately emetogenic chemotherapy who had been given dexamethasone 8 mg i.v. and either ondansetron 32 mg i.v. or dolasetron 2.4 mg/kg i.v. were randomized to continue either an oral form of their 5-HT3 antagonist (ondansetron 8 mg b.i.d. or dolasetron 200 mg daily) plus dexamethasone 8 mg p.o. daily or dexamethasone alone for days two to seven. Endpoints assessed by self-report were: 1) complete control (no vomiting, no rescue medications, no missing data) of emesis; 2) nausea severity; and 3) quality-of-life as measured by the EORTC QLQ-C30. RESULTS: Continuation of 5-HT3 antagonists improved slightly, but not significantly, the complete control rate (47% vs. 41%: P = 0.24 one-sided) after chemotherapy. However, mean nausea severity was significantly (P = 0.015 one sided) reduced (by 3 mm on a 10 cm scale) on the combined arm. Minimal differences in quality of life were observed. CONCLUSION: The benefit of continuing 5-HT3 antagonists beyond 24 hours is modest and the merits of routine use in these circumstances debatable.

Antiemetics↗
PubMed1997

In vitro optimisation of a microdialysis system with potential for on-line monitoring of lactate and glucose in biological samples.

The optimisation and evaluation of the microdialysis component of a prototype miniaturised total analysis system for application in the continuous monitoring of lactate and glucose is reported. The complete unit comprises a high efficiency microdialysis sampling system, a miniaturised microflow manifold with an integrated biosensor array, together with the hardware and software necessary for controlling the flow parameters and monitoring the sensor signals. Sampling occurs via a microdialysis shunt probe which is perfused continuously with a physiological buffered saline solution. The continuous dialysate outflow is presented to the biosensor array, resulting in the appropriate amperometric signals. Aspects of technological significance addressed here include probe membrane size, perfusate flow rate, sample flow rate, temperature change, probe sterilisation procedures, and heparin content of the physiological saline solution employed.

Biosensing Techniques↗
PubMed1997

Novel instrumentation for real-time monitoring using miniaturized flow systems with integrated biosensors.

A prototype miniaturized Total Chemical Analysis System (muTAS) has been developed and applied to on-line monitoring of glucose and lactate in the core blood of anaesthetized dogs. The system consists of a highly efficient microdialysis sampling interface sited in a small-scale extracorporeal shunt circuit ('MiniShunt'), a silicon machined microflow manifold and integrated biosensor array for glucose and lactate detection with associated computer software for analytical process control. During in-vivo testing the device allowed real-time on-screen monitoring of glucose and lactate with system response times of less than 5 min, made possible by the small dead volume of the microflow system. On-line glucose and lactate measurements were made in the basal state as well as during intravenous infusion of glucose or lactate. The prototype muTAS is currently suitable for trend monitoring but refinements are necessary before application of the system for determination of individual lactate values.

Animals↗
PubMed1997

Phase III double-blind comparison of dolasetron mesylate and ondansetron and an evaluation of the additive role of dexamethasone in the prevention of acute and delayed nausea and vomiting due to moderately emetogenic chemotherapy.

PURPOSE: To compare the efficacy of dolasetron and ondansetron in controlling nausea and vomiting in the first 24 hours; to evaluate the efficacy when dexamethasone is added to either drug in the first 24 hours; and to extend these comparisons over 7 days in patients receiving moderately emetogenic chemotherapy. PATIENTS AND METHODS: This was a multicenter, double-blind, randomized study with six parallel arms that used a 2 x 2 factorial design in chemotherapy-naive patients. In arm 1, dolasetron (2.4 mg/kg) was given intravenously (I.V.) prechemotherapy, followed 24 hours later by oral dolasetron (200 mg once daily) for 6 days. Arms 2 and 3 consisted of dolasetron and dexamethasone 8 mg I.V., followed 24 hours later by oral dexamethasone (8 mg once daily) in one arm, and oral dexamethasone and dolasetron in the other, also for 6 days. In arms 4, 5, and 6, ondansetron (32 mg I.V. or 8 mg orally twice daily) was administered in a similar manner to arms 1, 2, and 3 before and 24 hours after chemotherapy. Mean nausea severity (MNS) was assessed on a visual analog scale (VAS) in a daily diary. RESULTS: Of 703 patients enrolled, 696 were eligible. There were 343 dolasetron- and 353 ondansetron-treated patients; 57% of dolasetron-treated patients had complete protection in the first 24 hours versus 67% of patients who received ondansetron (P = .013). MNS was also more pronounced on the dolasetron arm (P = .051). Sixty-seven percent of patients who received added dexamethasone in the first 24 hours had complete protection, compared with 55% without dexamethasone (P < .001). MNS was significantly reduced with the addition of dexamethasone (P < .001). At 7 days, dolasetron and ondansetron had equivalent complete protection rates (36% and 39%, respectively). With the addition of dexamethasone, 48% of patients compared with 28% had complete protection (P < .001). MNS was significantly improved with added dexamethasone (P < .001). CONCLUSION: At the doses used, dolasetron was significantly less effective than ondansetron at controlling nausea and vomiting in the first 24 hours in patients receiving moderately emetogenic chemotherapy, but there was no demonstrable difference between both drugs over 7 days. The addition of dexamethasone significantly improved the efficacy of both drugs in the first 24 hours and over 7 days.

Administration, Oral↗
PubMed1996

Pharmacokinetics of single intravenous and oral doses of dolasetron mesylate in healthy elderly volunteers.

Dolasetron mesylate (MDL 73,147EF, Anzemet; Hoechst Marion Roussel, Laval, Canada) is a 5-HT3 receptor antagonist undergoing clinical evaluation for use as an antiemetic agent. The pharmacokinetics of dolasetron and its reduced metabolite (MDL 74,156) were studied after administration of single intravenous and oral doses of dolasetron mesylate 2.4 mg/kg in 18 healthy elderly subjects. Expressed as the dolasetron base, this dose was 1.8 mg/kg. Dolasetron was rapidly metabolized to the reduced metabolite, which appeared in plasma within 10 minutes after intravenous or oral administration. The mean half-life (t1/2) of dolasetron was 0.24 hours after intravenous administration and 0.50 hours after oral administration. The pharmacokinetic parameters of the reduced metabolite were similar after intravenous and oral administration. The apparent absolute bioavailability of the reduced metabolite was 89%, and it had an elimination t1/2 of approximately 7 hours and an apparent volume of distribution (Vd beta) of 4.69 L/kg. Dolasetron was not detected in urine. Metabolites were excreted in urine almost completely within 24 hours of administration. The primary metabolite detected in urine was the (+)-enantiomer of the reduced metabolite, which accounted for 25.35% (+/- 7.79%) and 18.88% (+/- 7.65%) of the intravenous and oral doses, respectively. Hydroxylated metabolites accounted for 5% or less of the total dose via either route. The pharmacokinetics of the reduced metabolite after single intravenous or oral doses in elderly volunteers were consistent with pharmacokinetics observed in both young healthy men and cancer patients receiving high-dose cisplatin chemotherapy. Dosage adjustments of dolasetron mesylate on the basis of age do not appear to be necessary.

Aged↗
PubMed1996

The role of CD11/CD18 integrins in the reverse passive Arthus reaction in rat dermal tissue.

The CD11/CD18 leukocyte integrins are necessary for tissue localization of neutrophils, an early requisite event in inflammation. We have analyzed the contribution of CD11a/CD18 and CD11b/CD18 to local neutrophil accumulation and tissue injury in the reverse passive Arthus reaction in the rat dermis. Experimental groups comprised animals that received an intravenous infusion of (1) recombinant neutrophil inhibitory factor (NIF), a hookworm-derived antagonist of CD11b/CD18; (2) monoclonal antibody to CD11a/CD18 (TA-3); (3) a combination of these agents; (4) a monoclonal antibody to CD18 (WT.3); or (5) saline. Administration of recombinant NIF or anti-CD11a/CD18 monoclonal antibody alone produced a slight reduction in neutrophil accumulation but did not affect edema formation. In contrast, a combination of these antagonists yielded a significant reduction in neutrophil accumulation and a modest reduction in edema, equivalent to levels observed with either anti-CD18 antibodies or animals that were rendered neutropenic. These results indicate that neutrophil infiltration in rat dermal tissue in the reverse passive Arthus reaction is dependent predominantly on the leukocyte integrins CD11a/CD18 and CD11b/CD18 and that either of these integrins is sufficient for neutrophil trafficking in this inflammatory setting.

Animals↗
PubMed1996

Pharmacokinetics of the active metabolite (MDL 74,156) of dolasetron mesylate after oral or intravenous administration to anesthetized children.

BACKGROUND: Dolasetron mesylate is a selective 5-HT3 receptor antagonist under investigation as an antiemetic in children. Published studies indicate that its antiemetic activity results from the active metabolite (MDL 74,156), which is produced within 10 minutes of administration of dolasetron mesylate. METHODS: The pharmacokinetics of MDL 74,156 and the safety and tolerability of dolasetron mesylate were studied after a single oral or intravenous dose of 1.2 mg.kg-1 dolasetron mesylate to healthy children from 2 to 12 years of age. Oral dolasetron was administered to 12 children 1 to 2 hours before anesthesia. Intravenous dolasteron was administered to 18 children at induction of anesthesia. Serial blood samples were collected for 24 hours after dosing to measure the plasma concentration of MDL 74,156. Indexes of liver and kidney function were determined, and electrocardiograms and adverse events were recorded.

Administration, Oral↗
PubMed1996

Effective/simple variance trending.

This article describes a simple, effective process that provides facilitated variance tracking while meeting the Joint Commission on Accreditation of Healthcare Organizations' requirement for Multidisciplinary Care Plans.

Critical Pathways↗
PubMed1996

An intravascular microdialysis sampling system suitable for application in continuous biochemical monitoring of glucose and lactate.

Direct sensor implantation for continuous biochemical monitoring has proved disappointing, but microdialysis sampling devices can serve as a biocompatible patient-sensor interface. We propose a novel "MiniShunt" extracorporeal microdialysis sampling circuit designed to sample core blood, and report the performance of different microdialysis probe membrane types and sizes with pumped and non-pumped blood flow in anaesthetised dogs. Discrete microdialysate and plasma samples collected during glucose and lactate monitoring were analysed with a YSI analyzer and showed microdialysis efficiency (% relative recovery) in excess of 95% for both analytes using fibres of greater than 70 mm2 internal surface area. Pumped veno-venous extracorporeal blood microdialysis sampling of this type could provide a suitable interface for future multi-analyte on-line biosensor applications in critically ill patients.

Animals↗
PubMed1994

Antibody-based approaches to coumarin analysis.

7-Hydroxycoumarin (7-HC) was chemically conjugated by diazo coupling to carrier proteins such as bovine serum albumin (BSA), thyroglobulin and ovalbumin. These conjugates were characterised by sodium dodecyl sulphate/polyacrylamide gel electrophoresis (SDS-PAGE) and high-performance liquid chromatography (HPLC). Rabbits were immunised using the 7-HC-BSA conjugate. The highest antibody titre achieved was 1:10,000, as determined by competitive enzyme-linked immunosorbent assay (ELISA). The resulting antibodies were purified by ammonium sulphate precipitation, followed by protein A affinity chromatography. Their purity was assessed by SDS-PAGE and HPLC. These antibodies have been used in the development of a competitive ELISA, an amperometric biosensor and an electrochemical immunoassay. Both the ELISA and amperometric biosensor have been successfully applied to the analysis of 7-HC and its glucuronide conjugate in human urine samples. Each of these antibody-based methods provides a novel approach to the analysis of the main metabolites of coumarin.

Animals↗
PubMed1993

Differential pulse voltammetric determination of 7-hydroxycoumarin in human urine.

The electrochemical behaviour of 7-OH-coumarin at the bare glassy carbon electrode has been studied using differential pulse voltammetry, and based on anodic detection of this metabolite at 0.66 V (vs SCE) using DC amperometry, a method has been developed for the determination of 7-OH-coumarin levels in urine samples, and a pharmacokinetic profile established.

Electrodes↗
PubMed1993

Development of an antibody-based amperometric biosensor to study the reaction of 7-hydroxycoumarin with its specific antibody.

An amperometric biosensor, based on an anti-7-hydroxycoumarin (7-OH-coumarin) antibody immobilized at the surface of a glassy carbon electrode, and contained behind a cellulose dialysis membrane, is described. The electrochemical behaviour of this metabolite at the bare glassy carbon electrode was found to be well defined by using differential-pulse voltammetry, and a 90% decrease in peak height was observed on binding of the antibody to the antigen, which occurs at the electroactive site of 7-OH-coumarin. The kinetics of the antibody-antigen reaction was investigated and a first-order reaction was observed with k = 0.0329 mA min-1. This system provides a novel method for studying antibody specificity and the kinetics of such antibody-antigen interactions.

Antibodies↗
PubMed1992

A lysine dehydrogenase-based electrode for biosensing of L-lysine.

An amperometric biosensor for L-lysine based on the recently isolated enzyme lysine dehydrogenase is described. Immobilization of the enzyme onto a platinum electrode is achieved via entrapment within a gelatin support on a cellulose membrane. Anodic detection (at 0.4 V vs. Ag/AgCl) is facilitated by the presence of a redox-mediating ferricyanide ion. The effect of experimental variables such as pH, enzyme loading, applied potential, cofactor and mediator concentrations were evaluated in order to optimize the analytical performance. A detection limit of 7 x 10(-8) M, and linearity up to 7 x 10(-4) M are reported. The fast response permits adaptation for flow injection operation with good precision (RSD = 1.9%) and high sample throughout (40 samples per hour). The high specificity offered by this new enzyme is indicated by the lack of interference by other L-amino acids, alcohols or carbohydrates.

Amino Acid Oxidoreductases↗
PubMed1991

Amperometric enzyme electrode for theophylline.

An amperometric biosensor for theophylline, based on the recently isolated enzyme theophylline oxidase, is described. The enzyme is entrapped, together with a ferricytochrome C cofactor, within a polymeric (Nafion) coating. The anodic detection (at +0.4 V versus Ag-AgCl) is facilitated by the addition of a redox-mediating hexacyanoferrate(III) ion. The influence of various experimental variables is described. The limit of detection is 2 x 10(-6) mol dm-3 theophylline, with linearity prevailing up to 3 x 10(-4) mol dm-3. The fast response and wash times permit rapid flow-injection measurements, with a frequency of 180 samples h-1 and a relative standard deviation of 3.0-4.0%. Prospects of using this electrode for clinical diagnostics are discussed.

Biosensing Techniques↗
PubMed1991

Effect of diltiazem on symptomatic and asymptomatic episodes of ST segment depression occurring during daily life and during exercise.

BACKGROUND: Silent myocardial ischemia is an adverse prognostic marker in patients with coronary disease; however, controlled data on the effect of treatment are sparse and contradictory, and the relations among the occurrence of ST segment depression, drug efficacy, and heart rate are unclear. METHODS AND RESULTS: Sixty patients with stable coronary artery disease, a positive treadmill exercise test and asymptomatic ST segment depression on ambulatory electrocardiographic recording were assessed in a multicenter, double-blind, placebo-controlled, cross-over trial. Treadmill exercise tests and 72-hour electrocardiographic recordings were obtained at the end of two 2-week treatment periods with sustained-release diltiazem 180 mg b.i.d. or equivalent placebo. Episodes of asymptomatic ST depression decreased by 50% or more in 70% of the patients from a median number of 4.5 (range, 0-19) to 1.5 (range, 0-13) (p = 0.0001); their cumulative duration also decreased from 78.5 (range, 0-60) to 24.5 (range, 0-411) minutes (p = 0.001). No circadian variation was found in the efficacy of diltiazem. The occurrence of ischemic type ST segment depression was modulated by changes in heart rate rather than by absolute heart rate. Diltiazem also improved exercise test end points but to a lesser extent. Time to ST segment depression increased to 341 +/- 148 from 296 +/- 154 seconds (p = 0.005). Although less frequent with diltiazem administration (45 versus 54 patients, p less than 0.03), exercise-induced ST depression was more often asymptomatic (98% versus 72% of patients, p less than 0.0001). CONCLUSIONS: Diltiazem reduces the frequency and severity of ischemic type ST depression in patients with stable coronary artery disease.

Activities of Daily Living↗