Prolonged granulocytopenia from incompatible platelet transfusions.
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Adult↗
Biomedical subjects
D G Poplack
Publications and source records attributed to D G Poplack.
Lipid peroxidation in the killing of phagocytized pneumococci.
To directly examine the role of hydrogen peroxide in the killing of bacteria after ingestion by granulocytes, we have studied some of the events of phagocytosis of a mutant strain of pneumococci which is relatively deficient in peroxide production. The hydrogen peroxide-deficient pneumococci and the otherwise identical wild type were grown with [(14)C]arachidonic and [(3)H]palmitic acid labels to label their lipids with unsaturated and saturated fatty acids, respectively. They were then incubated with both normal and chronic granulomatous disease granulocytes. The rates of ingestion and bacterial killing and the stability of fatty acids in the cell-bacteria complex were followed. Radioactive carbon dioxide released from glucose was also independently followed to measure glucose oxidation. Ingestion was similar for all cell-bacteria combinations. Chronic granulomatous disease cells killed the peroxide-positive wild pneumococci much more effectively (20-fold) than the peroxide-deficient mutant. Normal cells killed both peroxide-positive and -negative strains effectively. A considerable loss of [(14)C]arachidonic acid ( approximately 40%) consistent with lipid peroxidation of this unsaturated fatty acid was observed in all normal cells and in chronic granulomatous disease cells with peroxide-positive pneumococci. However, no loss of [(14)C]arachidonic acid occurred in chronic granulomatous disease cells with the peroxide-deficient pneumococci. No loss tritiated palmitic acid occurred in any cell-bacteria combination. Glucose oxidation was impaired in the chronic granulomatous disease cells in comparison to normal cells at rest and was especially impaired in chronic granulomatous disease cells ingesting the peroxide-deficient mutant pneumococci. This defect was partially corrected after phagocytosis of the peroxide-positive strain. These data directly support the hypothesis that bacterial killing is partially dependent upon an intact peroxide-generating system in the leukocyte-bacteria complex. Moreover, they indicate that bacterial lipid peroxidation is associated with the generation of peroxide during phagocytosis. Finally, they suggest that such peroxidation may contribute to effective phagocytic bacterial killing.
Animals↗
Cerebrospinal fluid pharmacokinetics and toxicology of intraventricular and intrathecal arabinosyl-5-azacytosine (fazarabine, NSC 281272) in the nonhuman primate.
Arabinosyl-5-azacytosine (AAC), a new nucleoside antimetabolite, is broadly active in preclinical tumor screening evaluations. To assess the potential for intrathecal use of this drug, we studied the toxicity and pharmacokinetics of intrathecal and intraventricular administration in nonhuman primates. Four adult male rhesus monkeys were given single 10 mg intrathecal (n = 1) or intraventricular (n = 3) doses of AAC to determine its acute toxicity and pharmacokinetic parameters. An additional 3 animals were given four weekly 10 mg intrathecal doses to assess the systemic and neurologic toxicity associated with chronic administration. Disappearance from the cerebrospinal fluid (CSF) was biexponential, and CSF clearance was 0.2 ml/min, which exceeds the rate of CSF bulk flow by 5-fold. The peak CSF concentration and area under the concentration x time curve achieved with the intraventricular administration of 10 mg were one hundred, and fifty fold greater, respectively, than those achieved after an intravenous dose of 200 mg/kg (1500-2400 mg) in prior experiments. No clinically evident neurotoxicity was observed in either the single or the weekly x 4 dose groups. A slight, transient CSF pleocytosis and increased CSF protein was observed. Systemic toxicity was limited to one animal in the weekly x 4 dose group who demonstrated a mild and transient decrease in his peripheral leukocyte count unassociated with a change in his hematocrit or platelet count. These studies in nonhuman primates demonstrate a clear pharmacokinetic advantage for intrathecal vs systemic administration of AAC. This is demonstrated by a 50-fold greater CSF drug exposure with an intrathecal or intraventricular dose 1/200th of that which can be given systemically.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
New cytotoxic drugs for intrathecal administration.
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Antineoplastic Agents↗
Chronic ventricular cerebrospinal fluid sampling, drug injections, and pressure monitoring using subcutaneous reservoirs in monkeys.
Animal models enabling reliable access to ventricular cerebrospinal fluid (CSF) are crucial to the study of neuropharmacological and neurotoxicological effects of cytotoxic agents used to treat central nervous system neoplasms. This investigation concludes that 4th ventricular catheterization using subcutaneous CSF reservoirs in rhesus monkeys: (a) provides chronic access to sterile CSF without chronic immobilization, (b) enables mixing of injected drugs with lateral ventricular CSF, (c) permits sensitive monitoring of intraventricular pressure and (d) does not produce tissue damage during cannula implantation or breakdown of the blood-brain barrier.
Animals↗
Pharmacokinetics and cerebrospinal fluid penetration of daunorubicin, idarubicin, and their metabolites in the nonhuman primate model.
PURPOSE: Idarubicin (4-demethoxy-daunorubicin) is more potent and less cardiotoxic than the commonly used anthracyclines, doxorubicin and daunorubicin. In addition, idarubicin is metabolized to an active metabolite, idarubicinol, in contrast to other anthracyclines whose alcohol metabolites are much less active than the parent drug. The current study was performed in nonhuman primates to determine the plasma and cerebrospinal fluid (CSF) pharmacokinetics of idarubicin and idarubicinol and to compare them to the pharmacokinetics of daunorubicin and daunorubicinol. METHODS: A dose of 30 mg/m2 of daunorubicin or 8 mg/m2 of idarubicin was administered intravenously over 15 minutes. Plasma and CSF were sampled frequently from the end of the infusion to 72 to 96 hours after infusion. Drug and metabolite concentrations were measured using high-pressure liquid chromatography (HPLC). RESULTS: Daunorubicin elimination from plasma was triphasic with a terminal half-life of 5.9 +/- 1.8 hours, area under the concentration-time curve (AUC) 22.5 +/- 9.2 mumol/L.min, and clearance 2790 +/- 960 mL/min/m2. Daunorubicinol elimination was biphasic with a terminal half-life 10.2 +/- 2.3 hours and an AUC 74.5 +/- 5.3 mumol/L.min. Idarubicin elimination was triphasic with terminal half-life of 12.3 +/- 11.4 hours, a AUC 10.8 +/- 3.7 mumol/L.min, and clearance 1650 +/- 610 mL/min/m2. Idarubicinol elimination was biphasic with a terminal half-life 28.7 +/- 4.2 hours and AUC 67 +/- 9.8 mumol/L.min. CSF penetration was low for both parent drugs and their metabolites. CSF idarubicin was measurable at a single time point (1 hour after administration) for 2 animals, and was not measurable for the third. The CSF to plasma concentration ratio at that time point was 8% in 1 animal and 15% in the other. Idarubicinol was detected in 2 to 4 samples at various times, appearing as early as 1 hour in 1 animal and persisting as late as 48 hours in another. The CSF to plasma concentration ratio at corresponding time points was 1.9 +/- 0.6%. Daunorubicin was measurable for < 6 hours after intravenous administration. For individual animals, the mean CSF to plasma concentration ranged from 4% to 12%. Daunorubicinol was detectable by 1 hour in 2 of 3 animals and by 3 hours in the other, and remained detectable at 24 hours in 2 of 3. The terminal half-life of daunorubicinol in CSF was 8.8 +/- 1.3 hours, the AUC was 1.8 +/- 1.5 mumol/L.min, and the AUCCSF to AUCplasma ratio was 2.4 +/- 1.9%. CONCLUSION: Idarubicin, idarubicinol, daunorubicin, and daunorubicinol penetrate poorly into the CSF after intravenous administration.
Animals↗
The disposition and metabolism of 2',3'-dideoxycytidine, an in vitro inhibitor of human T-lymphotrophic virus type III infectivity, in mice and monkeys.
The pharmacokinetics and metabolism of the anti-human T-lymphotrophic virus type III/lymphadenopathy-associated virus agent 2',3-dideoxycytidine have been examined in BDF1 mice and rhesus monkeys, with ancillary enzyme studies carried out on tissue derived from both the latter species and also from human subjects. For the pharmacokinetic studies, 2',3-dideoxycytidine and its catabolic product 2',3-dideoxyuridine have been separated and measured in plasma, urine, and cerebrospinal fluid by a reverse HPLC method. For metabolic studies, tritium-labeled drug (labeled in the 5- and 6-positions of the pyrimidine ring) has been employed, utilizing an ion exchange HPLC analytical method suitable for the separation of the parent nucleoside from its mono-, di-, and triphosphates in cell extracts and in tissue homogenates. The drug is rapidly cleared from plasma in a biphasic manner (terminal t 1/2 in BDF1 mice and rhesus monkeys of 67 min and 109 min, respectively) following an iv bolus dose of 325 mg/m2. This two-compartment open model is predictive of plasma concentrations during long term ip infusions in mice. Dideoxycytidine is predominantly excreted in the urine as unchanged parent compound, although a minor urinary metabolite (2,3-dideoxyuridine) is detected in the monkey but not in the mouse. Oral absorption of 2',3'-dideoxycytidine is rapid, with plasma levels approaching those seen after iv administration within 45 min in the mouse. Entry to the central nervous system is also rapid, but the cerebrospinal fluid to plasma AUC ratio after iv administration is only 0.026-0.040 in rhesus monkeys.(ABSTRACT TRUNCATED AT 250 WORDS)
Administration, Oral↗
Mechanism of acquired resistance to methotrexate in P388 murine leukemia cells and in their doxorubicin-resistant subline.
The mechanisms of acquired resistance to MTX were studied in P388 murine leukemia cell lines that were sensitive or resistant to ADR. The rate of MTX accumulation in ADR-sensitive cells that have acquired resistance to MTX was found to be lower than that measured in cells that were sensitive to both drugs. Furthermore, in contrast to drug-sensitive cells, in the ADR-sensitive MTX-resistant cells, most of the intracellular MTX (86.2%) was bound and MTX polyglutamation was not detected. The initial rate of MTX accumulation in cells that were resistant to both drugs was comparable to that measured in cells that were sensitive to both drugs or that were resistant only to ADR. However, in the cells that were resistant to both drugs, the rate of MTX accumulation was maintained at its initial level for a period that was considerably longer than that found in the other cell lines. After 3 h of exposure to MTX, the accumulation of MTX in cells that were resistant to both drugs was fourfold higher than that measured in cells that were sensitive to both drugs. Furthermore, while 65 to 70% of the intracellular MTX was free, in cells sensitive to both drugs, or resistant only to ADR, the corresponding value in cells that were resistant to both drugs was less than 1.5%, and a much lower proportion of the MTX was polyglutamated. The sensitivity to TMQ of ADR-sensitive, MTX-resistant cells was similar to that found in cells that were sensitive to ADR and MTX. However, ADR-resistant cells, sensitive or resistant to MTX, were markedly resistant to TMQ. The sensitivity of ADR-resistant MTX-sensitive cells to TMQ was restored by the presence of 10 microM verapamil. Such an effect was not observed in cells resistant to both drugs. It is suggested that P388 cells that have previously acquired resistance to ADR, when now selected by MTX, retain the MTX-transport system (in contrast to ADR-sensitive, MTX-resistant cells) and become resistant to MTX by increasing the activity of DHFR. The results obtained in ADR-resistant cells also suggested that resistance to TMQ was part of the multidrug resistance phenomenon.
Animals↗
Pharmacokinetics of 6-mercaptopurine (6MP) in the monkey. I. Disposition from plasma and cerebrospinal fluid following iv bolus.
The disposition profile of 6-mercaptopurine (6MP) was studied from plasma and cerebrospinal fluid (CSF) in the rhesus monkey following a single iv bolus dose (4 mg/kg). A new, sensitive, and specific high performance liquid chromatography procedure has been employed for drug quantitation in biological fluids. An equation consisting of three exponential terms was simultaneously fitted to the 6MP plasma and CSF concentration vs. time data using the SAAM 27 digital computer program. 6MP in plasma and CSF had a mean half-life (t1/2, lambda z) of 2.9 hr and an apparent volume of distribution (Vd, lambda z) of 3.00 liter/kg. Estimates of total body clearance average 0.731 +/- 0.412 liter/hr/kg and ranged between 0.446 and .1204 liter/hr/kg. In the postdistributive phase, the decline of 6MP concentration from the CSF paralleled plasma. The t1/2, lambda z obtained by fitting Ccsf vs. t data separately was not significantly different (p greater than 0.2) than the one obtained above in a simultaneous fitting of the data. Therefore, it appears that the unbound 6MP concentration in plasma may be the driving force in the diffusion of the drug into CSF. Comparison of experimental CSF/plasma ratio of 6MP with the theoretical values obtained using the pH-partition hypothesis is also discussed.
Animals↗
Pharmacokinetics of ICRF-187 in the cerebrospinal fluid of subhuman primates.
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Animals↗