Hematological toxicity of doxorubicin-containing protocols in dogs with spontaneously occurring malignant tumors.

The medical records of 49 dogs with spontaneously occurring malignant tumors treated with doxorubicin-based chemotherapy protocols were evaluated for hematological toxicity. Protocols included vincristine, doxorubicin, and cyclophosphamide (VAC); 5-fluorouracil, doxorubicin, and cyclophosphamide (FAC); doxorubicin and cyclophosphamide (AC); and doxorubicin and dacarbazine (ADIC). Prevalence of Grades 1, 2, or 3 toxicities were less than 30%, and the prevalence of Grade 4 toxicity alone was less than 5%. The frequency of sepsis was less than 2.5% in dogs treated with VAC, FAC, or AC, and it was 15% in dogs treated with ADIC. There were no significant differences in the prevalence or severity of hematological toxicity caused by VAC or AC. Five-fluorouracil, doxorubicin, and cyclophosphamide caused significantly more severe neutropenia than VAC or AC. The low prevalence of hematological complications makes these protocols acceptable for use in practice.

Randomized safety studies of intravenous perflubron emulsion. I. Effects on coagulation function in healthy volunteers.

Previous perfluorocarbon (PFC) emulsions have been associated with transient adverse events (i.e., platelet activation, decreased platelet count, febrile responses, changes in hemodynamic function). The Phase I studies described in this report were parallel, randomized, double-blinded, placebo-controlled studies conducted in 48 healthy volunteers (n = 24 per study) with perflubron emulsion (Oxygent; Alliance Pharmaceutical Corp., San Diego, CA). Because of the decreased platelet counts observed with previous PFC emulsions and the intended use of perflubron emulsion in surgical patients, these studies assessed postdosing coagulation responses and hemostasis. PFC pharmacokinetic variables were also evaluated. The primary endpoint for examination of coagulation effects was prospectively defined as bleeding time. Subjects received either saline (3 mL/kg) control, or perflubron emulsion at 1.2 g PFC/kg or 1.8 g PFC/kg, and were evaluated for a 14-day period. No postinfusion changes in bleeding time or differences in ex vivo agonist-induced platelet aggregation were observed. A 17% reduction in platelet count was observed 3 days after dosing in the 1.8-g PFC/kg group; levels recovered to baseline by Day 7. The intravascular half-life of perflubron for the first 24 h was dose dependent: 9.4+/-2.2 h and 6.1+/-1.9 h in the 1.8- and 1.2-g PFC/kg groups, respectively. Results indicate that this perflubron emulsion did not affect coagulation function in healthy volunteers.

The pharmacokinetics and pharmacodynamics of GW395058, a peptide agonist of the thrombopoietin receptor, in the dog, a large-animal model of chemotherapy-induced thrombocytopenia.

GW395058, a PEGylated peptide agonist of the thrombopoietin receptor, stimulates megakaryocytopoiesis and has previously been shown to increase platelet counts in vivo. The pharmacokinetics and pharmacodynamics of GW395058 were characterized using a randomized, crossover study in a large-animal model (dog) of chemotherapy-induced thrombocytopenia. Nine beagle dogs received i.v. carboplatin (350 mg/m(2)) on day 0 and day 28. GW395058 (1.31 mg/kg) (n = 6) or vehicle control (n = 3) was administered on day 1 and day 29 either as an i.v. bolus or s.c. injection. After i.v. administration, peak concentrations of GW395058 occurred rapidly, while the half-life averaged approximately 56 h. Bioavailability (+/- standard deviation) of GW395058 given s.c. was 78.2% (20.9%). GW395058 (i.v. and s.c.) ameliorated the platelet nadir (p = 0.0086) and resulted in a shorter time to recovery compared to the control group. The mean nadir platelet counts following carboplatin administration were 197,000 cells/microl (80,000) for the i.v. GW395058-dose group, 183,000 cells/microl (72,000) for the s.c.-dose group and 71,000 cells/microl (38,000) for the vehicle-alone group. GW395058 reduced the thrombocytopenic effects of carboplatin in dogs. No GW395058-related adverse side effects were observed.

Pharmacokinetic and pharmacodynamic study of the combination of docetaxel and topotecan in patients with solid tumors.

PURPOSE: The sequence in which chemotherapeutic agents are administered can alter their pharmacokinetics, therapeutic effect, and toxicity. We evaluated the pharmacokinetics and pharmacodynamics of docetaxel and topotecan when coadministered on two different sequences of administration. PATIENTS AND METHODS: On cycle 1, docetaxel was administered as a 1-hour infusion at 60 mg/m(2) without filgrastim and at 60, 70, and 80 mg/m(2) with filgrastim on day 1, and topotecan was administered at 0.75 mg/m(2) as a 0.5-hour infusion on days 1 to 4. On cycle 2, topotecan was administered on days 1 to 4, and docetaxel was administered on day 4. Cycles were repeated every 21 days. Blood samples for high-performance liquid chromatography measurement of docetaxel (CL(DOC)) and topotecan (CL(TPT)) total clearance were obtained on day 1 of cycle 1 and day 4 of cycle 2. CL(DOC) and CL(TPT) were calculated using compartmental methods. RESULTS: Mean +/- SD CL(DOC) in cycles 1 and 2 were 75.9 +/- 79.6 L/h/m(2) and 29.2 +/- 17.3 L/h/m(2), respectively (P: <.046). Mean +/- SD CL(TPT) in cycles 1 and 2 were 8.5 +/- 4.4 L/h/m(2) and 9.3 +/- 3.4 L/h/m(2), respectively (P: >. 05). Mean +/- SD neutrophil nadir in cycles 1 and 2 were 4,857 +/- 6, 738/microL and 2,808 +/- 4,518/microL, respectively (P: =.02). CONCLUSION: Administration of topotecan on days 1 to 4 and docetaxel on day 4 resulted in an approximately 50% decrease in docetaxel clearance and was associated with increased neutropenia.

Initial observations on the efficacy of highly active antiretroviral therapy in the treatment of HIV-associated autoimmune thrombocytopenia.

BACKGROUND: Immune thrombocytopenic purpura (ITP) occurs in as many as 40% of patients infected with the human immunodeficiency virus (HIV). We sought to evaluate the effect of highly active antiretroviral therapy (HAART) on platelet counts in such patients. METHODS: Data collected from 11 homosexual men with HIV-associated ITP and < or = 50 x 10(9) platelets were analyzed after they were placed on HAART. At initial evaluation, 7 patients were antiretroviral naive, 2 were taking zidovudine alone, and 2 were receiving combination antiretroviral therapy for known HIV infection. For 6 patients with <30 x 10(9) platelets, prednisone was initially coadministered with HAART. The primary outcome measure was the platelet count response to HAART, which was measured weekly until counts had normalized on 3 consecutive occasions, then every 3 months while on HAART. Secondary outcome measures were HIV-viral RNA levels and CD4+ cell counts. RESULTS: One month after the initiation of HAART, 10 evaluable patients had an increase in mean platelet count. This improvement was sustained at 6 and 12 months' follow-up for 9 of 10 evaluable patients. Increases in mean platelet count at 6 and 12 months of the 9 responders were statistically significant. The range of follow-up in the 9 responders is 21 to 46 months (median, 30 months), with no thrombocytopenic relapses. The 9 long-term platelet responders have been maintained on HAART and at 12 months had a mean reduction of > 1.5 log10 in HIV viral RNA serum levels and a marked improvement in CD4+ T-lymphocyte cell count. CONCLUSION: HAART seems to be effective in improving platelet counts in the setting of HIV-associated ITP, enhancing CD4+ cell counts, and reducing HIV viral loads.

The effect of long-term treatment with granulocyte colony-stimulating factor on hematopoiesis in HIV-infected individuals.

This randomized, placebo-controlled trial examine the long-term effect of granulocyte colony-stimulating factor (G-CSF) on absolute numbers of CD34+ progenitor cells and progenitor cell function in human immunodeficiency virus (HIV)-infected patients. G-CSF (300 microg filgrastim) or placebo was given three times weekly for 12 weeks to 30 HIV-infected patients that had been treated with HAART for at least 24 weeks and not yet achieved CD4 counts above 350 CD4+ cells/microl. Blood samples were collected at weeks 0, 2, 4, 8, and 12, and again 12 weeks after termination of the G-CSF treatment. Significant increase in absolute numbers of circulating CD34+ cells was detected in the treatment group (P = 0.006). The function of progenitor cells was examined in vitro using a colony-forming unit (CFU) assay, and increase in the number of CFU/ml was detected (P = 0.005). In order to estimate the effect of G-CSF on in vivo function of progenitors the white-blood count was determined. Significant increase in white-blood count was found (P < 0.001), while hemoglobin and platelet count decreased (P = 0.001 and P = 0.013, respectively). Significant increase in the CD4 count occurred, but correlation between the numbers of progenitors and the CD4 count was not found. These data suggest that G-CSF mainly increases the number and differentiation of myeloid progenitors.

The effects of heparin and extracorporeal circulation on platelet counts and platelet microaggregation during cardiopulmonary bypass.

BACKGROUND: Cardiopulmonary bypass is associated with platelet activation and reduced platelet counts. Platelet activation may artifactually lower platelet counts by causing aggregation. In vivo platelet activation may increase existent platelet microaggregation ex vivo. We studied platelet counts and existent platelet microaggregation at different stages of cardiopulmonary bypass. METHODS: Twenty-one patients were studied before and after heparinization (300 U. kg(-1)) and at the end of cardiopulmonary bypass. Unaggregated (or single) platelets were counted in hirudin-anticoagulated blood, and total platelets were counted in ethylenediaminetetraacetic acid-anticoagulated blood. RESULTS: The total platelet count, 198 +/- 61 x 10(9). L(-1), was unaffected by heparin and stayed at 197 +/- 60 x 10(9). L(-1) (P =.7) but fell during extracorporeal circulation; the hemodilution-corrected count was 163 +/- 52 x 10(9). L(-1) (P =.0004). Heparinization reduced the unaggregated platelet count from (mean +/- 1 SD) 178 +/- 62 x 10(9). L(-1) to 155 +/- 60 x 10(9). L(-1) (P =.0001). Extracorporeal circulation had little additional effect. The hemodilution-corrected count was 142 +/- 48 x 10(9). L(-1) (P =.6). CONCLUSIONS: Heparinization caused platelet activation and increased existent platelet microaggregation ex vivo. During extracorporeal circulation, there was a reduction in total platelets that was greater than could be explained by hemodilution alone, but the unaggregated platelet count did not change significantly when corrected for hemodilution. Furthermore, the increased platelet microaggregation observed after heparinization was no longer evident after this loss. These findings suggest that during extracorporeal circulation, the platelets that formed into microaggregates after heparinization were lost from the circulation in preference to single platelets.

Hematologic abnormalities and acute myeloid leukemia in children and adolescents administered intensified chemotherapy for the Ewing sarcoma family of tumors.

PURPOSE: Current treatment of the Ewing sarcoma family of tumors (ESFT) includes intensive multiagent chemotherapy with topoisomerase II inhibitors, alkylating agents, and granulocyte colony-stimulating factor (G-CSF). This treatment approach has been associated with myelodysplasia and acute myeloid leukemia. Because macrocytosis and thrombocytopenia are distinctive features of myelodysplasia, the authors evaluated a cohort of patients treated for ESFT to determine the degree and duration of macrocytosis and thrombocytopenia and their relation with the development of therapy-related hematologic malignancies. PATIENTS AND METHODS: The study group consisted of 73 patients with ESFT treated on two consecutive protocols (EW92 and EW87). Both chemotherapy regimens incorporated the same agents but differed in cumulative drug dose, dose per course, and the use of G-CSF. Platelet counts and the mean corpuscular volume (MCV) of erythrocytes were determined at diagnosis and during follow-up visits after completion of treatment. RESULTS: Patients in the EW92 group had significantly greater MCVs after treatment than did the less intensively treated EW87 group. These changes persisted throughout the 40-month observation period. Patients in the EW92 group also had lesser mean platelet counts after treatment than those in the EW87 group. MCV differences (from baseline) were inversely related to platelet counts. The cumulative incidence of treatment-related acute myeloid leukemia was 7.8%+/-4.7% at 4 years in the EW92 group and zero in the EW87 group. CONCLUSION: Patients treated for ESFT with intensive chemotherapy that includes large doses of alkylators, topoisomerase II inhibitors, and G-CSF characteristically have persistently elevated MCVs and decreased platelet counts after completion of therapy. These hematologic abnormalities may represent stem cell damage, predisposing patients to myelodysplasia and acute myeloid leukemia, but further study is needed to establish this relation.

EDTA-dependent pseudothrombocytopenia in a case of liver cirrhosis.

Pseudothrombocytopenia (PTCP) is the consequence of an EDTA-activated platelet agglutination, resulting in a spuriously low platelet count. We report the case of a 54-year-old man with EDTA-dependent PTCP associated with liver cirrhosis. He couldn't undergo endoscopic examination and dental care for two years because of a previous diagnosis of severe thrombocytopenia secondary to liver cirrhosis. Lack of PTCP recognition may lead the physician to misdiagnosis and mismanagement of the patient.

Impact of the patient population on the risk for heparin-induced thrombocytopenia.

The frequency of immune heparin-induced thrombocytopenia (HIT) varies among prospective studies. It is unknown whether this is caused by differences in the heparin preparations, the patient populations, or the types of serologic assay used to confirm the diagnosis. Seven hundred forty-four patients were studied from 3 different clinical treatment settings, as follows: unfractionated heparin (UFH) during or after cardiac surgery (n = 100), UFH after orthopedic surgery (n = 205), and low-molecular-weight heparin (LMWH) after orthopedic surgery (n = 439). Both an activation assay and an antigen assay were used to detect heparin-dependent IgG (HIT-IgG) antibodies. By activation assay, the frequency of HIT-IgG formation ranged from a low of 3.2% in orthopedic patients receiving LMWH to a high of 20% in cardiac patients receiving UFH; by antigen assay, the corresponding frequencies ranged from 7.5% to 50%. Both UFH use (P =.002) and cardiac surgery (P =.01) were more likely to be associated with HIT-IgG formation. However, among patients in whom HIT-IgG formed and who were administered UFH, the probability for HIT was higher among orthopedic patients than among cardiac patients (by activation assay: 52.6% compared with 5%; odds ratio, 21.1 [95% CI, 2.2-962.8]; P =.001; by antigen assay: 34.5% compared with 2.0%; odds ratio, 25.8 [95% CI, 3.2-1141]; P <.001). It is concluded that there is an unexpected dissociation between the frequency of HIT-IgG formation and the risk for HIT that is dependent on the patient population. HIT-IgG antibodies are more likely to form in patients who undergo cardiac surgery than in orthopedic patients, but among patients in whom antibodies do form, orthopedic patients are more likely to develop HIT. (Blood. 2000;96:1703-1708)

Haematological toxicity following different dosing schedules of 5-fluorouracil and epirubicin in rats.

AIM: To study the effects of single and fractionated doses of 5-fluorouracil and epirubicin on the leukocyte counts in rats. METHODS: Six different dosing patterns of each drug were injected within one day. The leukocytes were followed for 11-15 days. Pharmacokinetic models were developed using NONMEM. Quantitative and qualitative pharmacokinetic-pharmacodynamic relationships were investigated. RESULTS: A one-compartment model with non-linear elimination described 5-fluorouracil pharmacokinetics and a three-compartment model described epirubicin concentration data. Sigmoidal or basic Emax-models quantified the relationships between individual AUCs and decreases in leukocytes, for both drugs. Similar relationships between AUC and toxicity were found, regardless of whether the drugs were given as single or fractionated doses. CONCLUSION: Quantitative relationships between AUC and the effect on leukocytes were established for 5-fluorouracil and epirubicin. However, no schedule dependence was indicated for the schedules used in the study.

Hydroxyurea-induced marked oscillations of platelet counts in patients with polycythemia vera.

Two prospectively studied patients with polycythemia vera (PV) whose platelet counts showed marked periodic fluctuation during treatment with hydroxyurea (HU) are reported. Cycle lengths in both were approximately 28 to 30 days. In one patient, the cyclic process was no longer evident when treatment with HU was withheld, and it reappeared on treatment rechallenge. Circulating thrombopoietin (TPO) levels fluctuated out of phase with the platelet count despite markedly reduced TPO-receptor (c-Mpl) expression in bone marrow megakaryocytes. These observations suggest that the cyclic phenomenon may be related to both a transient state of HU-induced depletion of megakaryocytes and a concentration-dependent mitigation by TPO of the HU effect on megakaryocytes and their precursors. It is conceivable that the affected patients harbor a megakaryocyte progenitor pool whose apoptotic activity is differently modulated by either HU or high concentrations of TPO. (Blood. 2000;96:1582-1584)

Dietary fish oil reduces microvascular thrombosis in a porcine experimental model.

Microvascular thrombosis plays a significant role in the pathophysiology of ischaemic reperfusion injury. A fish oil-supplemented diet containing n-3 polyunsaturated fatty acids (PUFA) reduces thromboxane A(2) (TxA(2)) synthesis and, thus, vasoconstriction and platelet aggregation. The aim of this study was to elucidate whether n-3 PUFA in a porcine model of ischaemia and reperfusion injury 1) inhibit accumulation of platelets and fibrinogen in ischaemia-reperfusion injured tissue, 2) prolong the bleeding time, and 3) inhibit TxA(2) synthesis. Nine pigs were fed a standard diet supplemented with 7 g n-3 PUFA/day for 3 weeks. Nine pigs on the standard diet served as controls. Unilateral myocutaneous flaps were exposed to ischaemia for a period of 6 hours. Contralateral flaps were nonischaemic. Tissue contents of radioactive-labelled platelets and fibrinogen were measured after 4 hours of reperfusion. Platelet count, serum TxB(2), and the cutaneous bleeding time were measured before and after 3 weeks of diet. In the fish oil group, the accumulation of platelets was significantly reduced in all the myocutaneous flaps, except in the ischaemic skin part, when compared to control animals. Fibrinogen was significantly reduced in nonischaemic flaps, but not in ischaemic flaps. After the feeding period, the level of TxB(2) was significantly lowered in the fish oil group (p<0.01). No difference in the bleeding time was observed. Thus, dietary supplementation with n-3 PUFA inhibits the formation of microvasculatory thrombosis in this model.

Quantitative detection of platelet aggregates in whole blood without fixation.

Platelet counting detects lesser degrees of platelet aggregation than conventional aggregometry. In order to prevent progressive platelet aggregation or disaggregation after sampling it is customary to fix blood samples. However fixation may introduce other artefacts. We first compared stability of platelet counts in EDTA-, citrate- and r-hirudin-anticoagulated blood from healthy volunteers. Second, the stability of platelet counts in unfixed EDTA- and hirudin-anticoagulated blood was compared with glutaraldehyde-fixed blood in the same anticoagulants. Third, the effect of in vivo heparin administration on platelet counts in EDTA- and hirudin-anticoagulated blood was studied. Platelet counts within 2 h of collection were significantly higher in EDTA- than in hirudin- or citrate-anticoagulated blood (P = 0.002 vs. hirudin and P = 0.001 vs. citrate). Twenty-four hour counts in hirudin and EDTA were unchanged (P = 0.3 and P = 0.2, respectively, vs. earlier counts). Counts in citrate increased significantly (P = 0.007; n = 10). Platelet counts in fixed blood did not differ significantly from those in unfixed blood. Heparin administered for cardiopulmonary bypass reduced platelet counts in hirudin-anticoagulated blood from (mean +/- 1 standard deviation) 180 +/- 45 to 162 +/- 30 x 10(9) l-1 (P = 0.01; n = 14), without significantly lowering counts with EDTA-anticoagulation, consistent with increased platelet aggregation. Hirudin and EDTA provided stable platelet counts, suggesting that fixation is unnecessary.

Randomized, placebo-controlled, crossover trial of low-dose oral methotrexate in children with extended oligoarticular or systemic arthritis.

OBJECTIVE: Juvenile idiopathic arthritis (JIA) can persist through adolescence and adulthood, resulting in significant disability. The use of low-dose oral methotrexate (MTX) for persistent polyarthritis has been shown to be effective by the USA/USSR collaborative study group. However, 2 of the most disabling subgroups of JIA, systemic and extended oligoarthritis, were underrepresented in that study. The present study was therefore conducted to investigate the efficacy of MTX in these 2 subgroups. METHODS: Patients under the age of 16 years who fulfilled the International League of Associations for Rheumatology criteria for systemic or extended oligoarticular arthritis were eligible for this multicenter, double-blind, placebo-controlled crossover trial. Forty-five patients with systemic and 43 with extended oligoarticular arthritis were enrolled. The dosage of MTX or placebo was 15 mg/m2, which could be increased to 20 mg/m2 after 2 months. Core outcome variables were considered as primary measures, giving a final score of "improved" or "not improved." Secondary measures included scores of systemic features and biochemical laboratory measures. Assessment of function was not included since there were no validated functional measures at the start of this trial in 1991. RESULTS: In the extended oligoarticular arthritis group, MTX treatment produced significant improvement in 3 of 5 core variables (erythrocyte sedimentation rate, physician's global assessment of disease activity, and parent's global assessment of disease activity). By the primary improvement criteria, there was significant overall improvement during MTX treatment. In the systemic arthritis group, only 2 of 5 core variables were significantly improved (physician's and parent's global assessment of disease activity). Systemic features were not part of the core variables, but the systemic feature score was not significantly different between MTX and placebo treatment. There was no significant overall improvement in this group during MTX treatment. However, no significant interaction between disease subgroup and treatment effect was demonstrated. When the data from both disease subgroups were combined, there was significant clinical improvement during MTX treatment (P = 0.006). CONCLUSION: MTX 15-20 mg/m2 given orally once a week was found to be an effective treatment for both extended oligoarticular and systemic JIA in this shortterm trial. Long-term efficacy needs to be addressed in future studies.

Essential thrombocythemia and recurrent myocardial infarction.

We report the case of recurrent myocardial infarction with essential thrombocythemia (ET) in a 61-year-old female patient. Only one report of recurrence of myocardial infarction has been previously described. Coronary angiography 10 days after the infarction was normal. Thrombocythemia had been controlled with hydroxyurea.

Randomized, dose-escalation study of SD/01 compared with daily filgrastim in patients receiving chemotherapy.

PURPOSE: To explore the use of SD/01 (a polyethylene glycol-conjugated filgrastim shown in preclinical studies to have a prolonged half-life) in patients with chemotherapy-induced neutropenia. PATIENTS AND METHODS: Thirteen patients with non-small-cell lung cancer were randomized to receive daily filgrastim (5 microg/kg/d) or a single injection of SD/01 (30, 100, or 300 microg/kg) 2 weeks before chemotherapy and again 24 hours after administration of carboplatin and paclitaxel. Pharmacodynamic, pharmacokinetic, and safety analyses were performed. RESULTS: Peak serum concentrations of SD/01 and the duration of increased serum concentrations were dependent on the SD/01 dose. SD/01 concentrations remained increased longer in patients with chemotherapy-induced neutropenia. Prechemotherapy median absolute neutrophil counts (ANCs) in patients receiving SD/01 were increased in a dose-dependent fashion, with the duration of this effect also being dose dependent. After chemotherapy, median ANC nadirs were similar in the filgrastim cohort and the cohort receiving SD/01 30 microg/kg, with higher nadirs seen in the cohorts receiving SD/01 100 or 300 microg/kg. Dose-limiting toxicities were not noted. CD34(+) cells were mobilized in all cohorts. CONCLUSION: A single dose of SD/01 increases the serum concentration of SD/01 for several days in a dose-dependent fashion and is not associated with significant toxicity. The effects of SD/01 on ANC and CD34(+) cell mobilization are comparable or greater than those achieved with daily filgrastim. The self-regulation of this molecule provides a potential therapeutic advantage in a variety of clinical settings associated with neutropenia.

A randomized, double-blind trial of filgrastim (granulocyte colony-stimulating factor) versus placebo following allogeneic blood stem cell transplantation.

Blood stem cell transplantation (BSCT) results in rapid hematopoietic recovery in both the allogeneic and autologous transplant settings. Because of the large numbers of progenitor cells in mobilized blood, the administration of growth factors after transplantation may not provide further acceleration of hematopoietic recovery. A randomized, double-blind, placebo-controlled study was performed to determine the effects of filgrastim (granulocyte colony-stimulating factor; G-CSF) administration on hematopoietic recovery after allogeneic BSCT. Fifty-four patients with hematologic malignancies undergoing a related, HLA-matched allogeneic BSCT were randomly assigned to receive daily filgrastim at 10 microg/kg or placebo starting on the day of transplantation. A minimum of 3 x 10(6) CD34(+) cells/kg in the allograft was required for transplantation. All patients received a standard preparative regimen and a standard regimen for the prevention of graft-versus-host disease (GVHD). The median time to achieve an absolute neutrophil count greater than 0.5 x 10(9)/L was 11 days (range, 9-20 days) for patients who received filgrastim compared with 15 days (range, 10-22 days) for patients who received placebo (P =.0082). The median time to achieve a platelet count greater than 20 x 10(9)/L was 13 days (range, 8-35 days) for patients who received filgrastim compared with 15.5 days (range, 8-42 days) for patients who received placebo (P =.79). There were no significant differences for red blood cell transfusion independence, the incidence of acute GVHD, or 100-day mortality between the groups. The administration of filgrastim appears to be a safe and effective supportive-care measure following allogeneic BSCT.

Occurrence and clinical significance of pseudothrombocytopenia during abciximab therapy.

OBJECTIVES: This study determined the incidence of pseudothrombocytopenia during abciximab therapy administered for percutaneous coronary interventions and compared the clinical course of patients with pseudothrombocytopenia with the clinical courses of patients with thrombocytopenia and patients with normal platelet counts. BACKGROUND: Although pseudothrombocytopenia has been previously reported during therapy with abciximab, the incidence and significance of this occurrence are unknown. The failure to differentiate pseudothrombocytopenia from thrombocytopenia could lead to unnecessary interruption of abciximab infusions or to platelet transfusions. METHODS: The incidences of pseudothrombocytopenia and thrombocytopenia were determined in four large placebo-controlled abciximab trials: c7E3 Fab Antiplatelet Therapy in Unstable Refractory Angina (CAPTURE), Evaluation of 7E3 for the Prevention of Ischemic Complications (EPIC), Evaluation of Percutaneous Transluminal Coronary Angioplasty to Improve Long-term Outcome of c7E3 GpIIb/IIIa Receptor Blockade (EPILOG) and Evaluation of Platelet IIb/IIIa Inhibitor for Stenting (EPISTENT). The clinical features, bleeding complications and major clinical outcomes of patients with pseudothrombocytopenia and those with thrombocytopenia were compared with each other and with those of patients with normal platelet count. RESULTS: Pseudothrombocytopenia occurred in 2.1% (95% confidence intervals [CI]: 1.7%, 2.5%) of abciximab-treated patients and in 0.6% of placebo-treated patients (p < 0.001). Thrombocytopenia occurred in 3.7% (95% CI: 3.2%, 4.2%) of abciximab-treated patients and in 1.8% (95% CI: 1.3%, 2.3%) of placebo-treated patients (p < 0.001). Patients with thrombocytopenia had significantly higher rates of major bleeding, major decreases in hemoglobin and increased transfusion requirements of both blood and platelets compared with those without thrombocytopenia. By contrast, pseudothrombocytopenic patients did not differ from patients with normal platelet counts in any of the measures of blood loss or transfusion requirements. Thrombocytopenic patients, but not those with pseudothrombocytopenia, had increased rates of revascularization at 30 days and six months. As previously reported, there was also a higher rate of death and myocardial infarction in the thrombocytopenic patients. CONCLUSIONS: Pseudothrombocytopenia is the cause of more than one third (36.3%) of low platelet counts in patients undergoing coronary interventions who are treated with abciximab. This study demonstrates that pseudothrombocytopenia is a benign laboratory condition that does not increase bleeding, stroke, transfusion requirements or the need for repeat revascularization. It is important to recognize pseudothrombocytopenia so that the beneficial effects of abciximab are not lost by premature termination of therapy.

Hemodynamic changes and systemic activation of coagulation and fibrinolysis during controlled endotoxemia in pigs.

In this study, we have established a pig model that can combine extensive hemodynamic monitoring with simultaneous repetitive (serial) blood sampling for the study of multiple variables related to the hemostatic system. Sixteen healthy young pigs were studied to evaluate the influence of continuous endotoxin infusion on hemodynamic patterns and activation of coagulation and fibrinolysis. The chief aim of the study was to investigate the applicability of analytical methods primarily developed for use with human plasma samples in quantification of factors and reaction products of the porcine coagulation and fibrinolytic systems, and further, to use these methods to study the longitudinal changes in the plasma levels of these hemostatic variables as a consequence of endotoxin infusion. We found that acute, controlled endotoxemia induced a hemodynamic state of shock and reduced pulmonary gas exchange. Simultaneously, a gradual increase in peripheral blood mononuclear cell tissue factor activity was demonstrated, and increased maximally 5.5-fold 4 hours after onset of endotoxin infusion. Thrombin-antithrombin complexes increased in plasma to maximum levels after 3 hours, accompanied by an ethanol gelation test that was regularly positive after 1 to 2 hours, and fibrin monomer levels that gradually increased maximally 3.8-fold after 6 hours. These changes were followed by gradual decreases of both fibrinogen and factor VII levels, mainly due to consumption. Plasma levels of tissue type plasminogen activator activity peaked at 1.5 hours (11.3-fold increase), whereas the peak of plasminogen activator inhibitor-1 activity (14-fold increase at 4.5 hours) was delayed compared to tissue plasminogen activator and completely extinguished plasma tissue plasminogen activator activity. The sequential activation of coagulation and fibrinolysis established a procoagulant state favoring disseminated intravascular coagulation and microthrombus formation, potentially leading to multiple organ dysfunction.