Prophylactic treatment with activated prothrombin complex concentrate (FEIBA�) reduces the frequency of bleeding episodes in paediatric patients with haemophilia A and inhibitors

Orthopaedic complications are among the most disabling sequelae occurring in patients with haemophilia and inhibitors. Recurrent or refractory joint bleeds can lead to joint damage, limiting mobility and causing permanent disability. Activated prothrombin complex concentrates (aPCCs) are effective in controlling acute, intraoperative and postoperative bleeding in patients with haemophilia and inhibitors. The relatively long, dosing interval and safety profile distinguish aPCCs as a well-suited option for prophylaxis. Therefore, it is postulated that long-term routine aPCC administration will decrease the frequency of recurrent bleeds, prevent damage to normal joints, and slow the progression of existing joint disease in patients with inhibitors. To test this hypothesis, a retrospective chart audit was performed. In four treatment centres, five patients were identified who received aPCC [Factor Eight Inhibitor Bypassing Activity, Anti-Inhibitor Coagulant Complex (FEIBA); Baxter AG, Vienna, Austria] prophylactically for > or = 6 months to prevent or reduce further joint deterioration, reduce bleeding and prevent postsurgical bleeding. Median treatment duration was 15 months and included administration of >1300 doses of aPCC. Dosages ranged from 50 to 75 U kg(-1) three times per week in four patients; one patient received 100 U kg(-1) daily. Orthopaedic status was maintained in four patients and improved in one; the frequency of bleeding episodes was reduced in all patients. No adverse events or thrombotic complications were reported. This case series demonstrates that routine aPCC administration may be used safely and effectively to reduce the occurrence of bleeding episodes and to maintain or improve clinical joint status in some patients.

Use of factor VIII replacement during open heart surgery in a patient with haemophilia A

We present a patient with haemophilia undergoing cardiac surgery treated with continuous infusion factor VIII.

Pharmacokinetic interactions of cyclosporine with etoposide and mitoxantrone in children with acute myeloid leukemia

The purpose of this study was to assess the effect of the multidrug resistance modulator cyclosporine (CsA) on the pharmacokinetics of etoposide and mitoxantrone in children with de novo acute myeloid leukemia (AML). Serial blood samples for pharmacokinetic studies were obtained in 38 children over a 24-h period following cytotoxin treatment with or without CsA on days 1 and 4. Drug concentrations were quantitated using validated HPLC methods, and pharmacokinetic parameters were determined using compartmental modeling with an iterative two-stage approach, implemented on ADAPT II software. Etoposide displayed a greater degree of interindividual variability in clearance and systemic exposure than mitoxantrone. With CsA treatment, etoposide and mitoxantrone mean clearance declined by 71% and 42%, respectively. These effects on clearance, in combination with the empiric 40% dose reduction for either cytotoxin, resulted in a 47% and 12% increases in the mean AUC for etoposide and mitoxantrone, respectively. There were no differences in the rates of stomatitis or infection between the two groups. CsA treatment resulted in an increased incidence of hyperbilrubinemia, which rapidly reversed upon conclusion of drug therapy. The variability observed in clearance, combined with the empiric 40% dose reduction of the cytotoxins, resulted in statistically similar systemic exposure and similar toxicity.

KRN5500 induces apoptosis (PCD) of myeloid leukemia cell lines and patient blasts

The purpose of this study was to determine if KRN5500, a spicamycin derivative with a unique acyl tail, would induce programmed cell death (PCD) of myeloid leukemia cell lines and cryopreserved leukemic blasts from newly diagnosed children with acute leukemia (AL). Cells were incubated with varying concentrations (0-5 ng/ml) of KRN5500 and the percent PCD determined using a modified in situ end labeling (ISEL) technique with Klenow fragment. The percent PCD was calculated using the formula: Percent PCD (% PCD)=[number of apoptotic cells/(viable cells+apoptotic cells)]x100. DMSO (0.30% w/v) was added to the cells in culture as the positive control for PCD; the negative control was media or albumin. KRN5500 increased the amount of PCD significantly in all five of the tested cell lines; U937 41+/-1.8%, KG1a 40+/-0.3%, HEL 14+/-2.2%, HL-60 41+/-0. 9%, K562 36+/-2% (mean PCD+/-SD). Patient blasts exposed to KRN5500 had an increase in PCD when exposed to 2 ng/ml of agent from 2 to 8 h; acute myeloid leukemia patients 7.5+/-0.5% at 2 h to 43.5+/-1.6% at 8 h, and acute lymphocytic leukemia patients rose from 12.4+/-3.8% at 2 h to 29.9+/-11.6% after 8 h (mean+/-SE). Overall the PCD for the patient samples was 3.7 versus 28+/-4% at 2 and 8 h, respectively. PCD was proportional to the dose of KRN5500 and incubation time. Further pre-clinical and clinical studies are required.

Expression of chromosome 21-localized genes in acute myeloid leukemia: differences between Down syndrome and non-Down syndrome blast cells and relationship to in vitro sensitivity to cytosine arabinoside and daunorubicin

The high event-free survival rates of Down syndrome (DS) children with acute myeloid leukemia (AML) are due, in part, to increased in vitro sensitivity of DS myeloblasts to cytosine arabinoside (ara-C) and daunorubicin and the greater generation of ara-C triphosphate (ara-CTP) from ara-C compared with myeloblasts from non-DS patients (Taub et al, Blood 87:3395, 1996). This study further explores the molecular basis of chemotherapy sensitivity of DS AML patients by examining the expression of chromosome 21-localized genes in myeloblasts from newly diagnosed AML patients. Transcript levels of two chromosome 21-localized genes, cystathionine-beta-synthase (CBS) and superoxide dismutase (SOD), measured by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), were 12.0- and 3. 8-fold higher in DS compared with non-DS myeloblasts (P <.0001 and P <.0001, respectively). Conversely, there were no significant increases in transcripts for 2 other chromosome 21-localized genes, carbonyl reductase and the reduced folate carrier. CBS transcript levels correlated with both in vitro ara-C sensitivity measured by the 3-[4,5-dimethyl-thiazol-2-yl]-2,5-diphenyltetrazolium-bro mid e (MTT) assay (P =.003) and the generation of (3)H-ara-C triphosphate (ara-CTP) after in vitro incubations with 5 micromol/L (3)H-ara-C (P =.0003). Transcripts of deoxycytidine kinase were 2.6-fold higher in DS compared with non-DS cells and may be a factor in the enhanced metabolism of ara-C in DS cells. There was no significant correlation of SOD transcripts with in vitro ara-C and daunorubicin sensitivities. Increased CBS transcripts could result in elevated CBS activity, which modulates ara-C metabolism by altering reduced folate pools, deoxycytidine triphosphate pools, S-adenosylmethionine levels, and/or methylation of the deoxycytidine kinase gene. The further identification of the molecular mechanisms of chemotherapy sensitivity of DS AML patients may lead to significant improvements in the treatment and cure of AML.

Interleukin-12 (IL-12) enhances lysis of non-lymphoid leukemia cell lines in vitro

IL-2 augments the ability of natural killer (NK) cells to kill myeloid leukemia cells in vitro, and may have a role in the eradication of minimal residual disease (MRD) in AML patients. The ability to enhance lysis of AML cells without the toxicity of IL-2 would be a significant improvement in the use of biologics against AML. Recent interest in IL-12 suggested that this cytokine might meet these criteria. The aim of this study was to evaluate the ability of IL-12 to enhance the in vitro lysis of the non-lymphoid leukemia cell lines in a standard 51Chromium release assay. Effector cells from normal volunteers were incubated with varying concentrations of IL-12 or IL-2 for 18-20 h, then the 51Cr-labeled target cells from five different cell lines of AML origin were added for 4 h. Percent lysis was determined and plotted over four effector:target (E:T) ratios. Our results indicated that IL-12 was able to enhance lysis of all cell lines tested at > or =5 units/ml. When IL-2 was added to the culture at a low dose along with IL-12, there appeared to be a synergistic effect. Although anti-gamma interferon was able to inhibit the cytolytic potential of effectors activated by IL-12, the lysis could not be completely blocked. Thus, it appears that IL-12 has the ability to stimulate NK lysis indirectly through the induction of gamma interferon as well as an alternate mechanism not related to gamma interferon. Thus, IL-12 may have a beneficial role in the treatment of non-lymphoid leukemia.

Reconversion of bone marrow in Gaucher disease treated with enzyme therapy documented by MR

BACKGROUND

Skeletal complications are responsible for significant morbidity in Gaucher patients. Plain radiographs have been unreliable in assessing bone marrow infiltration and activity. A way to assess bone marrow improvement is needed during enzyme therapy.

OBJECTIVE

The purpose of this paper is to assess the usefulness of MR in following improvement of abnormal bone marrow in Gaucher patients on enzyme therapy.

MATERIALS AND METHODS

Three patients aged 2, 7, and 24 years underwent serial MR scans of the lower extremities before and during treatment with Alglucerase (two patients) and Imiglucerase (one patient). T1-weighted, T2-weighted, STIR and FSE T2-weighted images were utilized. Two patients were imaged after 16 months of therapy, and one patient was imaged after 6 months of therapy.

RESULTS

All patients had improvement in marrow signal consistent with partial reconversion to fatty marrow during treatment. The findings were more marked after prolonged therapy. T1-weighted images demonstrated findings most clearly.

CONCLUSION

MR consistently showed improvement in marrow signal in Gaucher patients on enzyme therapy. As smaller doses of enzyme therapy are the trend, MR can be utilized to determine if therapy is effecting a change in the bone marrow.

Transcranial Doppler, MRA, and MRI as a screening examination for cerebrovascular disease in patients with sickle cell anemia: an 8-year study

OBJECTIVE

The authors previously reported five transcranial Doppler ultrasonography (TCD) findings as significant in detecting clinical cerebrovascular disease in a 4-year study in patients with sickle cell disease. This is a follow-up to evaluate the validity of the original findings over another 4-year period during which the study population doubled. A clinical follow-up of the original asymptomatic sickle cell patients with positive TCD, MRA, and MRI was also made.

MATERIALS AND METHODS

Over an 8-year period TCD, MRI, and MRA were prospectively performed in 90 sickle cell patients who were clinically asymptomatic for stroke and in 27 sickle cell patients with clinical stroke.

RESULTS

Of the 4 out of original 46 control patients in 1992 who had positive MRA and TCD, 3 have subsequently had clinical stroke. None of the 9 original patients with positive TCD and positive MRI but negative MRA have developed stroke. All five original TCD indicators of disease were still significant (P < 0.05) for detecting clinical disease: maximum velocity in ophthalmic artery (OA) > 35 cm/s, mean velocity in middle cerebral artery (MCA) > 170 cm/s, resistive index (RI) in OA < 50, velocity in OA greater than in MCA, and velocity in posterior cerebral (PCA), vertebral, or basilar arteries greater than in MCA. An RI of < 60 in the DA was also now found to be significant [corrected]. Four additional factors were also significant: turbulence, PCA or ACA without MCA, RI < 30, and maximum velocity in MCA > 200 cm/s.

CONCLUSION

Positive MRA with a positive TCD in an asymptomatic patient in long-term follow-up suggests a trend for developing clinical stroke. A 4- to 8-year follow-up of nine patients with positive TCD, positive MRI, but not positive MRA did not show development of clinical stroke. Nine Doppler findings are significant in screening for clinically symptomatic vascular disease in sickle cell patients. It is recommended that children with sickle cell disease be screened for cerebrovascular disease with TCD. If one or two indicators of abnormality are present, MRA is recommended. If the MRA is positive, the patient may be considered for transfusion therapy or other treatment for prevention of stroke.

2-Chlorodeoxyadenosine (2-CDA) for the treatment of refractory or recurrent Langerhans cell histiocytosis (LCH) in pediatric patients

BACKGROUND

Pediatric patients with Langerhans cell histiocytosis (LCH) may become refractory to conventional therapy or present with repeated recurrences over several years. Current therapeutic options such as prednisone, vinblastine, etoposide, and cyclosporine are associated with significant acute toxicities and late effects. Recent reports suggested that 2-chlorodeoxyadenosine (2-CDA) may be an effective agent in adults with LCH. The purpose of this study was to determine the safety and efficacy of 2-CDA in children with LCH.

METHODS

This report presents the data collected from the first three patients that have completed this trial. Patients were enrolled in a prospective study after informed consent was obtained. Patients had a confirmed diagnosis of LCH that had recurred several times or not responded to standard therapy. Patients were given a starting dose of 5 mg/M2 of daily continuous infusion for three days duration. Two patients had their dose increased to 6.5 mg/M2/ day. A total of 4-6 courses were given, and courses were repeated every 3-4 weeks. Thirteen of fifteen courses were given as outpatients at home.

RESULTS

Each patient completed therapy with myelosuppression the primary toxicity. Pt. 1 initially received a higher dose of 2-CDA and developed sepsis. The dose was reduced to current study levels and no other incidence of infection, fever, and neutropenia, or blood product transfusion was required. All three patients are free of active disease 10-18 months after completing 2-CDA.

CONCLUSION

Three patients with LCH refractory to standard therapy had CR to 2-CDA, given at 5-6.5 mg/M2/day for 3 days, without significant toxicity.

Transient lupus anticoagulants associated with hemorrhage rather than thrombosis: the hemorrhagic lupus anticoagulant syndrome

Lupus anticoagulants (LAs) represent a diverse group of antibodies directed against phospholipids. Patients with LAs may be free of symptoms but can have thrombotic complications including stroke, placental infarction, and fetal loss. Rarely hemorrhagic symptoms have been reported. We describe six previously healthy children who were first seen with clinical bleeding and prolonged activated partial thromboplastin time. Laboratory evaluation revealed positive results on mixing studies and evidence of phospholipid dependence of the anticoagulant, suggesting LAs. Four of six patients had anticardiolipin antibodies, and all four who were tested had reduced factor II activity levels. In all patients, bleeding symptoms resolved spontaneously within 3 months, and laboratory findings returned to normal within 6 months. The hemorrhagic LA syndrome should be considered in previously healthy children with new-onset bleeding and prolonged activated partial thromboplastin time. This clinical entity probably represents pathogenic mechanism distinct from thrombotic LA syndromes.

Secondary acute myelogenous leukemia following safe exposure to etoposide

PURPOSE

To present two patients as illustrations of the risk of developing secondary acute myelogenous leukemia (sAML) when theoretically safe doses of etoposide (VP-16) are used.

PATIENTS AND METHODS

Patient no. 1 was a 15-year-old white girl diagnosed with stage IIa Hodgkin's disease. She was treated with a combination of vincristine, doxorubicin, bleomycin, and VP-16 (2 g/m2 total) over 4 months, followed by 25.5 Gy of involved-field radiotherapy. Patient no. 2 was an 11-year-old white boy diagnosed with virus-associated hemophagocytic syndrome (VAHS). He was treated with VP-16 intravenously (IV) and orally (0.3 g and 2.8 g/m2, respectively).

RESULTS

Patient no. 1 developed AML 16 months from the diagnosis of Hodgkin's disease. Patient no. 2 developed AML 26 months from diagnosis. Both bone marrows were consistent with French-American-British (FAB) M4 disease. Both patients had abnormalities of the long arm of chromosome 11.

CONCLUSION

The use of low-dose or oral VP-16 can be associated with the development of sAML. Clinicians should be cautious in the use of VP-16 in low-risk diseases.

DDAVP therapy controls bleeding in Ehlers-Danlos syndrome

PURPOSE

Patients with Ehlers-Danlos syndrome (EDS), especially types IV, VI, and VIII, are at increased risk of bleeding, and most do not have specific hemostatic deficiencies that would be amenable to replacement therapy. We have investigated the ability of DDAVP (desmopressin acetate) to control bleeding in EDS.

PATIENTS AND METHODS

Two children with EDS, types VIII and VI, presented with hemorrhagic symptoms and scheduled surgical procedures. Ivy bleeding times (BTs) were measured before and after intravenous (i.v.) DDAVP challenge, and i.v. DDAVP was used prophylactically for their procedures. Laboratory testing was performed to rule out other hemostatic disorders.

RESULTS

Both patients had prolonged BTs that corrected following i.v. DDAVP therapy; all other laboratory values were normal. Both patients had excellent clinical hemostasis with surgery, and one has continued to use intranasal DDAVP to control epistaxis and gingival bleeding.

CONCLUSIONS

The bleeding time in both patients was corrected with DDAVP, and the patients did not have any postoperative bleeding. DDAVP should be considered in other patients who have EDS with bleeding tendencies.

Serotype-specific immunoglobulin G antibody responses to pneumococcal polysaccharide vaccine in children with sickle cell anemia: effects of continued penicillin prophylaxis

OBJECTIVES

(1) To determine serotype-specific IgG antibody responses to reimmunization with pneumococcal polysaccharide vaccine at age 5 years in children with sickle cell anemia and (2) to determine whether continued penicillin prophylaxis had any adverse effects on these responses.

STUDY DESIGN

Children with sickle cell anemia, who had been treated with prophylactic penicillin for at least 2 years before their fifth birthday, were randomly selected at age 5 years to continue penicillin prophylaxis or to receive placebo treatment. These children had been immunized once or twice in early childhood with pneumococcal polysaccharide vaccine and were reimmunized at the time of randomization.

RESULTS

Serotype-specific IgG antibody responses to reimmunization varied according to pneumococcal serotype but in general were mediocre or poor; the poorest response was to serotype 6B. The antibody responses were similar in subjects with continued penicillin prophylaxis or placebo treatment, and in subjects who received one or two pneumococcal vaccinations before reimmunization. The occurrence of pneumococcal bacteremia was associated with low IgG antibody concentrations to the infecting serotype.

CONCLUSIONS

Reimmunization of children with sickle cell anemia who received pneumococcal polysaccharide vaccine at age 5 years induces limited production of serotype-specific IgG antibodies, regardless of previous pneumococcal vaccine history. Continued penicillin prophylaxis does not interfere with serotype-specific IgG antibody responses to reimmunization.

Cerebrovascular disease in symptomatic and asymptomatic patients with sickle cell anemia: screening with duplex transcranial Doppler US--correlation with MR imaging and MR angiography

PURPOSE

The authors evaluated the role of transcranial Doppler ultrasonography (US) in patients with sickle cell disease (SCD) and cerebrovascular disease.

MATERIALS AND METHODS

Twenty-one patients with SCD and stroke (aged 3-22 years; mean age at stroke, 9 years) were evaluated with magnetic resonance (MR) imaging and duplex transcranial Doppler US with a 2-MHz transducer. Nineteen patients also underwent MR angiography. Forty-six asymptomatic patients with SCD were also evaluated with Doppler US, MR imaging, and MR angiography.

RESULTS

The following transcranial Doppler US findings were correlated with cerebrovascular disease in patients with SCD: (a) maximum velocity in the ophthalmic artery (OA) of more than 35 cm/sec; (b) mean velocity in the middle cerebral artery (MCA) of more than 170 cm/sec; (c) resistive index in the OA of less than 50; (d) velocity in the OA greater than that of the ipsilateral MCA; and (e) maximum velocity in the posterior cerebral, vertebral, or basilar arteries greater than the maximum velocity in the MCA.

CONCLUSION

Transcranial Doppler US scanning has great potential as an inexpensive, easily performed screening procedure for cerebrovascular disease in patients with SCD.

Ceftazidime versus ceftazidime plus tobramycin in febrile neutropenic children

Although the effectiveness of antibiotic monotherapy in febrile neutropenic patients remains unproven, ceftazidime has been shown previously to be effective monotherapy for the empiric treatment of selective patients. The efficacy and safety of ceftazidime versus ceftazidime plus tobramycin was evaluated in the treatment of febrile children (range 8 months to 18 years) with neutropenia secondary to cancer chemotherapeutic agents. Of the evaluable 89 patients, 45 received ceftazidime and 44 received ceftazidime plus tobramycin for 5 to 10 days. At the end of therapy, 30 (67%) of the 45 ceftazidime-treated patients were clinically cured compared with 38 (86%) of 44 combination-treated patients. Thirteen (29%) of the patients treated with ceftazidime failed to respond clinically to treatment, versus four (9%) of the patients treated with ceftazidime/tobramycin (p = 0.046). This study suggests that ceftazidime as monotherapy in febrile neutropenic children may be inferior to combination therapy for optimal clinical response in these patients.

Single institution experience with high-dose cyclophosphamide, continuous infusion vincristine, escalating doses of VP-16-213, and total body irradiation with unpurged bone marrow rescue in children with neuroblastoma

Seven consecutive autologous bone marrow transplants were performed in children with neuroblastoma with very good partial remission (VGPR). A combination of cyclophosphamide, escalating doses of VP-16-213, continuous infusion vincristine, and total body irradiation followed by infusion with unpurged bone marrow was used. The dose-limiting toxicity in this regimen was mucositis which occurred when the total dose of VP-16-213 was 2,400 mg/m2. The response rate to this regimen was 4/7 (-CR 48+, 21+, 21+, 35+ mo) 3/7 had a CP/PR post transplant with progressive disease between 1 and 4 months later (mean 2.6 mo). We conclude that this regimen is well tolerated when the maximum dose of VP-16-213 does not exceed 1,800 mg/m2. Further evaluation will be necessary with this regimen to determine its therapeutic value in a larger number of patients with neuroblastoma.

Postdelivery head bleeding in hemophilic neonates. Causes and management

During a 12-month period, four of the five infants with hemophilia known to have been born in Arkansas were examined for head bleeding. Three of the infants had had traumatic delivery, with use of low forceps in two and vacuum extraction in one. In the fourth patient, hemophilia was prenatally diagnosed, and vaginal delivery resulted in cephalohematoma. Diagnosis was delayed in three patients, including one with a family history of hemophilia. Central nervous system bleeding may be more common in hemophilic neonates than has been presumed. Pregnancy management should include consideration of family history of bleeding disorders and carrier testing in appropriate cases. In confirmed carriers, prenatal diagnosis is justified to allow choice of the least traumatic delivery method. Any term neonate with intracranial hemorrhage should be treated as being possibly hemophilic until proved otherwise.

Antileukemic effects of deferoxamine on human myeloid leukemia cell lines

Deferoxamine (DFO) possesses antiproliferative activity against mitogen-stimulated lymphocytes, several tumor cell lines, and human leukemia and neuroblastoma cells. We have investigated its effects on the human myeloid leukemia lines HL-60, HEL, and U-937. In suspension culture, DFO causes a dose-dependent inhibition of proliferation of each cell line, with maximal inhibition observed at concentrations greater than 20 microM. These effects were prevented by cotreatment with iron salts and were at least partially reversible by removal of DFO from the culture system or addition of iron before 48 h of DFO exposure. Similar results were obtained in methylcellulose cultures of leukemic cells, with complete abolition of cell aggregates at day 7 in concentrations of 20 microM DFO or higher. DFO treatment caused a dose- and time-related decrease in DNA synthesis as measured by [3H]thymidine uptake, which was also reversed by treatment with iron salts. DFO caused slight reduction in RNA synthesis and did not affect protein synthesis. DFO caused significant antiproliferative effects on three myeloid leukemia cell lines, associated with inhibition of DNA synthesis, with in vitro effects observed at concentrations attainable in vivo. Evaluation of the antileukemic properties of DFO should continue.

Deferoxamine inhibition of human neuroblastoma viability and proliferation

Patients with widespread neuroblastoma (NB) frequently have elevated serum ferritin levels, and recently anti-NB effects of the iron chelator deferoxamine (DFO) have been reported. We have investigated the effect of DFO on human bone marrow NB cells from two untreated children with Evans Stage IV disease. DFO treatment caused dose- and time-dependent cytotoxicity of NB cells, with maximal killing at exposure to 50 micron DFO for 72 h. Cytotoxicity was prevented by cotreatment with stoichiometric amounts of iron salts and reversible by removal of DFO or addition of iron salts within 48 h of treatment. Additionally, DFO inhibited clonal growth of human bone marrow NB cells in methylcellulose in a time- and dose-dependent manner. These effects were also prevented by cotreatment with iron salts. Thus, DFO has potent antitumor effects on human NB cells which appear to be related to iron deprivation. DFO should be considered for further preclinical evaluation as an anti-NB agent.

An experience with an implanted port system in 66 children with cancer

Totally implanted port catheter systems have a lower incidence of infection and are more easily used in home care that external catheters in adult cancer patients. Experience with this method in children has been limited. During the past 2 years, we have implanted 71 ports in 66 children with cancer. Our experience demonstrates an infection rate (0.15 episodes of bacteremia per 100 patient days) slightly lower than that reported for children with Broviac or Hickman catheters, but not as low as that seen in adults with implanted systems. Patients and families have been extremely satisfied with the devices. Our experience supports further use of implanted systems in children with cancer.

Thrombotic thrombocytopenic purpura in an asplenic patient with hereditary spherocytosis: failure of plasmapheresis, antiplatelet therapy, and corticosteroids

Thrombotic thrombocytopenic purpura (TTP) is a severe multisystem disorder characterized by microangiopathic hemolysis, central nervous system and renal dysfunction, and a very poor prognosis. Recently, however, plasma exchange or infusion therapy has proven effective in the majority of patients with TTP. We report a patient who developed TTP several years after splenectomy for hereditary spherocytosis. Despite aggressive therapy with plasmapheresis (PP), plasma infusion, antiplatelet drugs, and corticosteroids, the patient had progression of TTP that eventually resulted in his death. The occurrence of TTP in an asplenic patient with an intrinsic red cell disorder, a previously unreported association, may predict a poor prognosis.

Natural history of histiocytosis-X

Histiocytosis-X can involve many organs and tissues in all age groups and in both sexes and occurs most often in caucasians. The signs and symptoms observed in the patient are directly related to the infiltration of Langerhans histiocytes, which compress or displace normal tissues and cause destruction of the tissues and organs involved. The disease tends to be benign and self-limiting when the involvement is limited to only one site. When more than one site is involved, the disease course can be chronic or acute. The chronic course tends to smolder for years, causing significant morbidity and disability but not death. The acute form tends to cause significant morbidity and early mortality.

Isolated vocal cord hematoma in a child with severe factor VIII deficiency

We have reported the first case of isolated submucosal hematoma of the true vocal cord in a hemophilic patient. He was managed with factor VIII replacement therapy as an outpatient for five consecutive days, without complication. Similar but more serious cases usually require more aggressive intervention by the pediatrician and the otolaryngologist.

Treatment of lymphohistiocytic erythrophagocytosis with VP-16 and aziridinylbenzoquinone

Lymphohistiocytic erythrophagocytosis (LE) is a usually fatal disease characterized by fever, organomegaly, hyperlipidemia, central nervous system involvement, and cellular immunodeficiency. Treatment with corticosteroids, cytotoxic chemotherapy, and blood exchange is unsuccessful. We have treated two children with the epipodophyllotoxin VP-16 and with intrathecal chemotherapy. Each patient had an initial complete response, and one remains in remission 36 months after therapy began. Aziridinylbenzoquinone (AZQ) therapy induced a complete response in a patient who relapsed during VP-16 therapy. A combination of VP-16 and intrathecal chemotherapy appears to be the most effective therapy for LE, and further evaluation of the role of AZQ is indicated.

Bacterial endocarditis in a child with a Broviac catheter

Broviac and Hickman catheters facilitate the care of children with cancer but provide a source of potential infection. We describe a child with a Broviac catheter who developed left-sided bacterial endocarditis in whom right-to-left atrial shunting was documented following catheter flushing. Following removal of the catheter and administration of prolonged intravenous antibiotics, recovery was complete and cardiac function returned to normal.

Analysis of deficiencies in IFN-gamma-mediated priming for tumor cytotoxicity in peritoneal macrophages from A/J mice

The functional and biochemical responses of macrophages derived from the A/J mouse strain to IFN-gamma have been studied. As compared to macrophages obtained from C57BL/6 strain mice, cells from mice of the A/J strain are deficient in their response to IFN-gamma for acquisition of tumoricidal competence. This deficiency was not due to reduced expression of surface receptors for IFN-gamma or to altered affinity of the receptor for its ligand. IFN-gamma recently has been shown to enhance the potential activity of protein kinase C (PKc) and to modulate the efflux of intracellular Ca2+ in macrophages from C57BL/6 mice. Neither of these two biochemical changes were induced in macrophages derived from A/J mice. Functional competence could, however, be pharmacologically induced in both C57BL/6- and A/J-derived macrophages by combined treatment with an ionophore plus phorbol myristic acetate, which increase intracellular Ca2+ and stimulate PKc, respectively. Although the exact nature of the deficit in A/J strain mice has not been defined, the present findings indicate that it lies between the expression of receptor and the modulation of PKc activity and Ca2+ levels. Furthermore, the data provide support for the notion that these molecular changes are important components of the stimulus-response coupling process in IFN-gamma-mediated activation of macrophages.

Analysis of deficiencies in IFN-gamma-mediated priming for tumor cytotoxicity in peritoneal macrophages from A/J mice

The functional and biochemical responses of macrophages derived from the A/J mouse strain to IFN-gamma have been studied. As compared to macrophages obtained from C57BL/6 strain mice, cells from mice of the A/J strain are deficient in their response to IFN-gamma for acquisition of tumoricidal competence. This deficiency was not due to reduced expression of surface receptors for IFN-gamma or to altered affinity of the receptor for its ligand. IFN-gamma recently has been shown to enhance the potential activity of protein kinase C (PKc) and to modulate the efflux of intracellular Ca2+ in macrophages from C57BL/6 mice. Neither of these two biochemical changes were induced in macrophages derived from A/J mice. Functional competence could, however, be pharmacologically induced in both C57BL/6- and A/J-derived macrophages by combined treatment with an ionophore plus phorbol myristic acetate, which increase intracellular Ca2+ and stimulate PKc, respectively. Although the exact nature of the deficit in A/J strain mice has not been defined, the present findings indicate that it lies between the expression of receptor and the modulation of PKc activity and Ca2+ levels. Furthermore, the data provide support for the notion that these molecular changes are important components of the stimulus-response coupling process in IFN-gamma-mediated activation of macrophages.

An infant girl with severe autoimmune hemolytic anemia: apparent anti-Vel specificity

Autoantibodies directed against the common red-cell antigen Vel are unusual, with only 2 previous cases reported. This report describes an infant girl with steroid-resistant autoimmune hemolytic anemia whose serum contained an antibody with apparent specificity for Vel antigen. Transfusion with Vel-positive cells resulted in a massive hemolytic transfusion reaction. Survival of labelled Vel-negative cells was normal up to 8 h following transfusion, and no transfusion reaction followed subsequent use of Vel-negative cells. There was no evidence of a collagen vascular disease, an immunodeficiency syndrome, or a malignancy. Although rare, anti-Vel should be considered in unexplained autoimmune hemolytic anemia.

Severe Mycoplasma pneumonia in three sisters with sickle cell disease

Mycoplasma pneumoniae, which usually causes mild infections in normal children, has been shown to cause isolated cases of severe pneumonia in children with sickle cell disease. We recently observed an outbreak of Mycoplasma pneumonia in three sisters with homozygous sickle cell disease. Two of them required hospitalization, and one progressed to respiratory failure requiring prolonged ventilatory assistance. All eventually recovered without long-term pulmonary complications. Familial outbreaks are not uncommon in Mycoplasma infection, but they have not been described previously in siblings with sickle cell disease. It is assumed that local or systemic host defense abnormalities predispose patients with sickling syndromes to more severe courses of Mycoplasma infections.

Characterization of protein kinase C activity in interferon gamma treated murine peritoneal macrophages

Macrophage activation for tumoricidal and microbicidal functions can be achieved in part by treatment with recombinant interferon gamma (IFN gamma) in vitro. We have previously demonstrated that IFN gamma treatment of murine peritoneal macrophages results in a two- to five-fold increase in the activity of Ca++, phospholipid dependent protein kinase C (Hamilton et al., J. Biol. Chem., 260:1378, 1985). We now report that this effect was not dependent upon continuing protein synthesis since treatment with cycloheximide under conditions where normal protein synthesis was inhibited by greater than 95% had no effect upon the development of increased enzyme activity. Examination of Ca++ and phospholipid requirements revealed no differences between enzyme isolated from control or IFN gamma treated cells. Similarly, protein kinase C from control and IFN gamma-treated cells could not be distinguished in terms of the diacylglycerol (DG) or phorbol diester (PMA) concentration required for stimulation of activity. Kinetic analysis of the ATP (as substrate) concentration dependence revealed that both control and treated enzyme preparations (either basal or stimulated) had comparable Km values. Maximum velocity (Vmax) was increased both by IFN gamma treatment and also by stimulation with DG or PMA. The major difference which could be discerned between protein kinase C derived from control versus IFN gamma-treated macrophages was the magnitude of the response to DG or PMA; IFN gamma treatment increased the stimulation index (i.e., ratio of basal to stimulated activity) by a factor of two to four fold. These results suggest that IFN gamma treatment leads to reversible modulation of existing protein kinase C resulting in increased catalytic efficiency when exposed to an appropriate stimulant.

Interferon-gamma modulates protein kinase C activity in murine peritoneal macrophages

The content of Ca2+-, phospholipid-dependent protein kinase activity (protein kinase C) in murine peritoneal macrophages treated with recombinant interferon-gamma (IFN-gamma) has been investigated. Protein kinase C activity was solubilized by nonionic detergent extraction of sonicated cells and separated by high performance liquid chromatography on a TSK 4000 SW gel filtration column. The enzyme eluted from the column in a molecular weight range of 60-80 X 10(3) and was identified by virtue of Ca2+ and phospholipid requirements. Macrophages treated with recombinant IFN-gamma exhibited a substantial increase in total protein kinase activity which could be accounted for entirely by increased protein kinase C activity. This activity was enhanced as much as 5-fold over that seen in untreated macrophages and was specific for IFN-gamma in that other agents known to signal changes in macrophage function had no effect. The time required for the elevation of kinase activity was identical to that required for induction of other functions by IFN-gamma in macrophages. These observations suggest that protein kinase C may be a focus of regulatory action in IFN-gamma-mediated macrophage activation.