The use of ATP bioluminescence as a measure of cell proliferation and cytotoxicity

Thrombotic complications in childhood acute lymphoblastic leukemia: a meta-analysis of 17 prospective studies comprising 1752 pediatric patients

L-Asparaginase is an effective antineoplastic agent, used in the acute lymphoblastic leukemia chemotherapy. It has been an integral part of combination chemotherapy protocols of pediatric acute lymphoblastic leukemia for almost 3 decades. The potential of L-asparaginase as a drug of leukemia has been a matter of discussion due to the high rate of allergic reactions exhibited by the patients receiving the medication of this enzyme drug. Frequent need of intramuscular injection has been another disadvantage associated with the native preparation. However, of late these clinical complications seem to have been addressed by modified versions of L-asparaginase. PEG-L-asparaginase proves to be most effective in this regard. It becomes important to discuss the efficacy of L-asparaginase as an antileukemic drug vis-a-vis these disadvantages. In this review, an attempt has been made to critically evaluate the pharmacological and clinical potential of various preparations of L-asparaginase as a drug. Advantages of PEG-L-asparaginase over native preparations and historical developments of therapy with l-asparaginase have also been outlined in the review below.

Pharmacological and clinical evaluation of L-asparaginase in the treatment of leukemia.

Analytical applications of liquid-phase chemiluminescence

Light-emitting chemical reactions (chemiluminescence, CL) and biological reactions (bioluminescence, BL) have a diverse range of analytical applications but relatively few have been adopted by routine clinical laboratories. Advantages of CL and BL assays include sensitivity (attomole and sub-attomole detection limits), speed (signal generated in a few seconds and in some cases stable for several hours), nonhazardous reagents, and simple procedures. The most promising clinical applications are in immunoassay, protein blotting, and DNA probe assays. Chemiluminescent molecules exploited as labels include luminol, isoluminol, acridinium esters, thioesters and sulfonamides, and phenanthridinium esters. Separation and nonseparation assays have been devised, based on isoluminol and acridinium ester labels. The combination of the amplification properties of an enzyme and a CL or BL detection reaction provides a highly sensitive analytical system. Since 1983, CL and BL methods have been developed for many enzyme labels, e.g., alkaline phosphatase, glucose-6-phosphate dehydrogenase, horseradish peroxidase, Renilla luciferase, and xanthine oxidase. Currently, the most successful enzyme assays are the enhanced CL method for a peroxidase label involving a mixture of luminol, hydrogen peroxide, and an enhancer (e.g., p-iodophenol) and the direct CL method for alkaline phosphatase, with an adamantyl 1,2-dioxetane phenyl phosphate as substrate. Both systems are very sensitive (the detection limit for alkaline phosphatase when using the dioxetane reagent is 0.001 amol) and produce long-lived light emission (greater than 30 min), which is ideal for membrane applications in which light emission is detected with photographic film or a charge-coupled device camera.

Chemiluminescent and bioluminescent techniques.

L-asparaginase treatment reduces the anticoagulant potential of the protein C system without affecting vitamin K-dependent carboxylation

BACKGROUND AND METHODS Seventeen adult patients with acute lymphoblastic leukemia (ALL) treated with L-asparaginase (20,000 IU/m2 on six alternate days) were infused with antithrombin III (AT III) concentrates (Kybernin P, Behring). Substitution therapy was aimed at increasing the reduced AT III concentration usually found in these patients, since AT III deficiency is thought to be associated with an increased risk of thrombosis. Two schedules of AT III administration, different in dosage, timing and duration were evaluated. The first 7 patients (group A) received a fixed dose of 2,000 U every day for 6 times, starting with the second L-asparaginase (L-ase) infusion, independently of their plasma AT III levels. In the following 10 patients (group B), 20-25 U/Kg b.w. were administered daily for 7 times only when the plasma AT III level was lower than 60% with plasma fibrinogen higher than 100 mg/dl and platelet count higher than 50 x 10(9)/l, or when AT III was below 40%. Thirteen patients who received L-ase without AT III substitution served as controls. RESULTS AND CONCLUSIONS Both substitution regimens resulted in mean plasma AT III nadir values significantly (p less than 00.1) higher than in the controls. Our data suggest that, in ALL patients receiving L-ase according to the L20 protocol, satisfactory plasma AT III levels may be assured with infusions of 20-25 U/Kg b.w./day for 7-10 days, starting by day 2 of L-ase treatment.

A regimen for antithrombin III substitution in patients with acute lymphoblastic leukemia under treatment with L-asparaginase.

The effects of interferon (IFN) alpha-2a treatment on platelet function were evaluated in 20 patients affected by essential thrombocythaemia (ET). Baseline data documented the well-known abnormalities of in vitro platelet aggregation and the constant presence of a delta-storage pool deficiency. The therapy in all patients reduced the platelet count, and in the majority of them caused a partial improvement of in vitro platelet aggregation. Although the mean intraplatelet ADP level improved during treatment, it always remained below the normal range documenting persistence of the delta-storage pool deficiency. The plasma beta-TG levels, which initially were high, significantly decreased during treatment, but the beta-TG ratio and the platelet beta-TG values always remained within the normal range--this suggests an absence of platelet activation either before or during therapy. Our results demonstrate that, despite significantly reducing the platelet count, IFN alpha-2a treatment only partially corrects the qualitative platelet abnormalities in ET.

Platelet function and interferon alpha-2a treatment in essential thrombocythaemia.

The observation of two clinical cases make possible an evaluation of the potential therapeutic activity of platelet function inhibitors in thrombotic thrombocytopenic purpura (TTP). In particular, the clinical and hematological effects of ticlopidine (TC), employed alone in two TTP patients, are reported. The mechanism of action of this peculiar antiplatelet drug is mainly represented by the inhibition of fibrinogen binding on the platelet surface. In the first patient, a 45-year-old female in whom plasma-exchange (PE) and corticosteroids (C) led to a partial remission (platelets 80 x 10(9)/l), treatment with TC at a dose of 750 mg/day was carried out, and after 6 weeks a normal platelet count was observed. A complete remission was maintained for 31+ months, even after reduction of the TC dose to 250 mg/day. In the second patient, an 18-year-old female affected by relapsing TTP, a complete remission obtained with PE and C was maintained for 19 months in concomitance with TC treatment, started at a dose of 750 mg/day and lowered to 250 mg/day. After 11 months of treatment at this low dosage there was a relapse (platelets 20 x 10(9)/l), but the increase of the TC dose to 750 mg/day in a few weeks induced a complete remission again. These data, in accord with a few other recent preliminary reports, suggest that TC, even alone, may play an interesting role in the management of TTP patients.

Ticlopidine in the treatment of thrombotic thrombocytopenic purpura: report of two cases.

We report on the cases of two women with acute thrombotic thrombocytopenic purpura (TTP) whose clinical courses were characterized by the onset of a coma state. Prompt commencement of plasma-exchange (PE) treatment led to complete hematological and neurological remission, which can still be observed without any maintenance therapy. No CNS abnormalities were observed in either patient using brain CT and NMR scans.

Cascione Ml

Papers

L-asparaginase treatment reduces the anticoagulant potential of the protein C system without affecting vitamin K-dependent carboxylation

A regimen for antithrombin III substitution in patients with acute lymphoblastic leukemia under treatment with L-asparaginase.

Platelet function and interferon alpha-2a treatment in essential thrombocythaemia.

Ticlopidine in the treatment of thrombotic thrombocytopenic purpura: report of two cases.

Prompt plasma-exchange treatment and coma reversibility in two patients with thrombotic thrombocytopenic purpura.