Topological quantum computing with only one mobile quasiparticle

In a topological quantum computer, universal quantum computation is performed by dragging quasiparticle excitations of certain two dimensional systems around each other to form braids of their world lines in 2 + 1 dimensional space-time. In this Letter we show that any such quantum computation that can be done by braiding n identical quasiparticles can also be done by moving a single quasiparticle around n - 1 other identical quasiparticles whose positions remain fixed.

Adenovirus-mediated p53 gene therapy in osteosarcoma cell lines: sensitization to cisplatin and doxorubicin

The poor prognosis for patients with metastatic osteosarcoma (OS) indicates that new therapeutic options should be explored. Studies with adenoviral-mediated p53 gene transfer have been conducted in many cancer types including cervical, ovarian, prostatic and head and neck tumors. However, limited work has been carried out with pediatric cancers, including OS. Using three viral constructs containing cDNA for wild-type p53, mutant p53 (Cys135Ser) and lacZ, we studied the effect of adenoviral-mediated gene therapy in four OS cell lines: Saos-2 (p53-/-), HOS (R156P), KHOS/NP (R156P) and MNNG (R156P, F270L). We demonstrated that the virus efficiently enters the cells using the beta-galactosidase assay. Using the MTT assay, we have shown a dose-dependent decrease in cell viability 72 h post-treatment that occurs with Ad-wtp53 but not with Ad-mutp53. We have also shown that treatment with Ad-wtp53 significantly increases sensitivity of the cell lines to cisplatin and doxorubicin, chemotherapeutic agents commonly used in the treatment of OS. Our results indicate that restoration of wt p53 function in OS cells provides a basis for novel approaches to treatment of this disease.

In vitro cytoprotective activity of squalene on a bone marrow versus neuroblastoma model of cisplatin-induced toxicity. implications in cancer chemotherapy

The development of a non-toxic selective cytoprotective agent that preferentially protects normal tissues from chemotherapy toxicity, without protecting malignant tissues, is a major challenge in cancer chemotherapy research. The available cytoprotective agents are either toxic or lack selective cytoprotective activity. Here, we report the in vitro selective cytoprotective activity of squalene, an isoprenoid molecule with antioxidant properties. Normal human bone marrow (BM) derived colony-forming unit (CFU) growth was increased by squalene in a dose-dependent manner. Squalene (12.5-25 microM) treatment significantly protected the CFUs from cisplatin-induced toxicity; the protective effect was equivalent to reduced glutathione (GSH), a known cytoprotective agent. Squalene also increased the long-term survival of cisplatin-treated 4-week-old CFUs. Cisplatin-induced apoptosis of CFUs as measured by the TUNEL assay was reduced by squalene. To examine the squalene-induced protection of tumours, several neuroblastoma cell lines, including five MYCN-amplified cell lines, were grown in monolayers, as well as in anchorage-independent cultures, in the presence of squalene and cisplatin. Squalene did not protect the neuroblastoma (NBL) cell lines from cisplatin-induced toxicity. In addition, squalene did not protect the NBL cells from carboplatin, cyclophosphamide, etoposide and doxorubicin-induced toxicity. In conclusion, our results suggest that squalene has a selective in vitro cytoprotective effect on BM-derived haematopoietic stem cells that is equipotent to GSH.

Allogeneic bone marrow transplantation vs chemotherapy for children with Philadelphia chromosome-positive acute lymphoblastic leukemia

Allogeneic bone marrow transplant (BMT) with an MRD in complete remission (CR)1 is the preferred treatment for children with Philadelphia-positive (Ph(+)) ALL. The role of MUD BMT in CR1 is still controversial. We compared the outcomes of two treatment strategies: BMT using an MRD or MUD vs chemotherapy in children with Ph(+) ALL in CR1. In total, 21 children were treated from 1985 to 2001. In all, 10 received chemotherapy and 11 received allogeneic BMT: four MRD, seven MUD. In the MRD group, one relapsed 12 months after BMT and died; the remaining three are long-term event-free survivors (median follow-up, 6.1 years). In the MUD group four died; the remaining three are long-term event-free survivors (median follow-up, 7.2 years). The 4-year event-free survival (EFS) for the BMT group was 53+/-15%. In the chemotherapy group, seven relapsed after a median period of 12.5 months and three remain in continuous CR (median follow-up, 2.4 years). Four chemotherapy patients received CR2 transplants; all died. The 4-year EFS for the chemotherapy and MUD groups was 33+/-17 and 35.7+/-20%, respectively. This difference was not statistically significant. We continue to support treating children with Ph(+) ALL with MRD BMT in CR1. The effectiveness of MUD BMT vs chemotherapy merits further study.

Low-intensity hematopoietic stem-cell transplantation across human leucocyte antigen barriers in dyskeratosis congenita

Since the results of conventional hematopoietic stem-cell transplantation (HSCT) for patients with dyskeratosis congenita (DC) are poor owing to the high incidence of transplant-related complications, we explored the use of a low-intensity HSCT regimen. We report two children with DC with severe cytopenia, who underwent successful HSCT from a matched unrelated donor after conditioning with fludarabine, cyclophosphamide, and antithymocyte globulin. Graft-versus-host-disease (GVHD) prophylaxis consisted of corticosteroids and cyclosporin A. The regimen was well tolerated, no significant transplant-related complications were observed, and engraftment was rapid and complete. At 15 and 16 months after HSCT, the children were fully engrafted, in excellent clinical condition, full-donor chimerism, and no signs of GVHD. We conclude that a low-intensity regimen is sufficient to induce durable engraftment using matched unrelated donor HSCT in DC patients, with minimal 1-year transplant-related toxicity. Longer follow-up will determine whether this regimen also reduces long-term toxicity.

Single-centre experience with allogeneic bone marrow transplantation for acute lymphoblastic leukaemia in childhood: similar survival after matched-related and matched-unrelated donor transplants

Seventy percent of children with acute lymphoblastic leukaemia (ALL) who may benefit from bone marrow transplant (BMT) lack a human leucocyte antigen (HLA)-matched related donor (MRD). For these children, BMT from a matched unrelated donor (MUD) represents a therapeutic option. We reviewed the course of 62 children with ALL who received fully matched marrow allografts at our institution between 1990 and 1998: 36 with MRDs and 26 with MUDs. Clinical characteristics were similar in the two groups. The interval from attainment of pre-BMT complete remission to transplant was significantly longer in the MUD group. Conditioning (etoposide/total body irradiation) and graft-versus-host disease (GVHD) prophylaxis regimens were the same for all patients, and all received T cell-replete bone marrow. There was no significant difference in probability of engraftment, or time to engraftment, in the two groups. MUD BMT recipients had a significantly greater incidence of grade II-IV acute GVHD (58% versus 24% in the MRD group; P = 0.02), and demonstrated a trend towards more chronic GVHD (39% versus 15%; P = 0.06). Three years post BMT, the probabilities of transplant-related mortality were 33 +/- 11% and 20 +/- 8% in MUD and MRD groups respectively (P = 0.38); the probabilities of relapse were 28 +/- 12% and 41 +/- 9% respectively (P = 0.19). Lansky or Karnofsky performance scores in event-free survivors were 90-100 in 87% of the MUD group and 83% of the MRD group. With a median follow up of 38 months (range, 3-97), 3-year event-free survival was 49 +/- 11% and 47 +/- 9% in the MUD and MRD BMT groups respectively (P = 0.71). These results suggest that MUD BMT is a valuable therapy for children with ALL in whom BMT is indicated, and underscore the importance of efforts aimed at expediting unrelated donor searches for patients lacking a MRD.

Immune function in patients with Shwachman-Diamond syndrome

Shwachman-Diamond syndrome (SDS) is an inherited multisystem disorder characterized by exocrine pancreatic dysfunction and varying degrees of cytopenia. In addition, various immunological abnormalities have been noted. To clarify the issue of immunological competence or incompetence in SDS, we prospectively studied immune function in 11 patients with SDS. Seven suffered from recurrent bacterial infections and six from recurrent viral infections. Varying degrees of impairment were readily identified. All patients had neutropenia; total lymphocyte counts, however, were normal in all except one patient. Nine patients had B-cell defects comprising one or more of the following abnormalities: low IgG or IgG subclasses, low percentage of circulating B lymphocytes, decreased in vitro B-lymphocyte proliferation and a lack of specific antibody production. Seven out of nine patients studied had at least one T-cell abnormality comprising a low percentage of total circulating T lymphocytes or CD3+/CD4+ cell subpopulations or decreased in vitro T-lymphocyte proliferation. Five out of six patients studied had decreased percentages of circulating natural killer cells. Moreover, neutrophil chemotaxis was significantly low in all the patients studied. These data point to a major immunodeficiency component in SDS that places patients at heightened risk of infections, even if neutrophil numbers are protective. This finding broadens the definition of the syndrome substantially: it suggests that the SDS marrow defect occurs at the level of an early haematological-lymphocytic stem cell or that a combined marrow and thymic stromal defect accounts for the aberrant function of haematopoietic and lymphopoietic lineages.

Shwachman-Diamond syndrome marrow cells show abnormally increased apoptosis mediated through the Fas pathway

Shwachman-Diamond syndrome (SDS) is an inherited bone marrow disorder with varying cytopenias and a strong predilection to myelodysplastic syndrome (MDS) and acute myeloid leukemia. Previously, it was found that the percentage of CD34(+) cells in bone marrow and the in vitro colony formation from CD34(+) cells of patients with SDS were markedly reduced. For these reasons, and because apoptosis is central in the pathogenesis of bone marrow dysfunction in MDS, this study was initiated to delineate the role of apoptosis in the pathogenesis of the marrow failure. Eleven children with SDS were studied. Compared to normal controls, patients' marrow mononuclear cells plated in clonogenic cultures showed a significantly higher tendency to undergo apoptosis. The defect in SDS was found in patients with and without MDS. Patients showed a more prominent decrease in colony formation and increased apoptosis after preincubation with activating anti-Fas antibody. Fas expression on marrow cells from patients was significantly higher than from normal controls. The difference between patients and controls for Fas expression was also significant for the following cell fraction subpopulations: CD34(-)/CD38(-), CD34(-)/CD38(+), and CD34(+). In conclusion, SDS hematopoietic progenitors are intrinsically flawed and have faulty proliferative properties and increased apoptosis. Bone marrow failure in SDS appears mediated by increased apoptosis as the central pathogenetic mechanism. This increased propensity for apoptosis is linked to increased expression of the Fas antigen and to hyperactivation of the Fas signaling pathway.

Differences in cell cycle kinetics of candidate engrafting cells in human bone marrow and mobilized peripheral blood

Patients undergoing hematopoietic stem cell transplantation (HSCT) with mobilized peripheral blood (MPB) engraft quicker than those receiving bone marrow (BM). Our objective was to determine whether candidate engrafting cells--primitive hematopoietic progenitors (PHPs)--from MPB and BM exhibit different responses to cytokines that could explain this observation. We compared the cell cycle kinetics and ex vivo expansion of PHP-enriched cells obtained from MPB (n = 12) and BM (n = 10) by fluorescence-activated sorting of CD90+, AC133+ or CD38(dull) subsets of pre-selected CD34(+) cells. Cell cycle status, before and after 40 hours of serum-free culture with a cytokine cocktail, was assessed by multiparameter flow cytometry following incubation with Hoechst 33342 and pyronin Y. We found that 0.2% +/- 0.3% of MPB CD34(+)CD90(+) cells were in S/G(2)/M phases at hour 0, compared with 5% +/- 2.5% of those from BM (p = 0.0001), and 86.3% +/- 9.7% were in G(0), compared with 65.3% +/- 10% of those in BM (p = 0.0001). After 40 hours of culture, CD34(+)CD90(+) cells from MPB were more mitotically active than those from BM, with 29% +/- 4.9% in S/G(2)/M and 20% +/- 11.4% in G(0), compared to 19% +/- 6.5% (p = 0.001) and 39.2% +/- 22% (p = 0.027) of cells from BM. There was greater expansion of both total CD34(+) cells and the CD90(+) subset from MPB samples (p = 0.001 and 0.0001, respectively). Results from PHPs defined on the basis of AC133 expression correlated well with results obtained in CD90(+) subsets (r(2) = 0.81; p = 0.014).MPB PHPs appear to be primed for a greater acceleration in mitotic activity upon cytokine exposure. This qualitative difference may contribute to the earlier engraftment seen after HSCT using MPB grafts.

Replicative stress after allogeneic bone marrow transplantation: changes in cycling of CD34+CD90+ and CD34+CD90- hematopoietic progenitors

To further characterize hematopoietic "replicative stress" induced by bone marrow transplantation (BMT), the cell-cycle status of CD90+/- subsets of marrow CD34+ cells obtained 2 to 6 months after transplantation from 11 fully chimeric recipients was examined. Cycling profiles, derived by flow cytometry after staining with Hoechst 33342 and pyronin Y, were compared with those of 14 healthy marrow donors. Primitive CD34+CD90+ cells represented a smaller proportion of CD34+ cells in recipients (10% +/- 4% versus 19.6% +/- 5.3% in donors; P <.0001) and were more mitotically active, with the proportion of cells in S/G2/M nearly 4-fold higher than in donors (15.6% +/- 3% and 4.4% +/- 1.6%, respectively; P <.0001). By comparison, there was a modest increase in the proportion of CD34+CD90- progenitors in S/G2/M after BMT (10.9% +/- 1% vs 9.6% +/- 2% in donors; P =.04). Replicative stress after BMT is borne predominantly by cells in a diminished CD34+CD90+ population.

Differential sensitivity of various pediatric cancers and squamous cell carcinomas to lovastatin-induced apoptosis: therapeutic implications

3-Hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase is the rate-limiting enzyme of the mevalonate pathway, the diverse array of end products of which are vital for a variety of cellular functions, including cholesterol synthesis and cell cycle progression. We showed previously that this enzyme holds a critical role in regulating tumor cell fate, including cell death, as its expression is down-regulated in response to retinoic acid, a potent anticancer therapeutic. Indeed, direct inhibition of HMG-CoA reductase with lovastatin, a competitive inhibitor of this enzyme, induced a pronounced apoptotic response in neuroblastoma and acute myeloid leukemic cells. We have now extended this work and evaluated a wide variety and large number of tumor-derived cell lines for their sensitivity to lovastatin-induced apoptosis. These cell lines were exposed to a wide range (0-100 microM) of lovastatin for 2 days and assayed for cell viability using the 3,4,5-dimethyl thiazlyl-2,2,5-diphenyltetrazolium bromide assay and the induction of apoptosis by flow cytometric and ultrastructural analyses. Lovastatin induced a pronounced apoptotic response in cells derived from juvenile monomyelocytic leukemia, pediatric solid malignancies (rhabdomyosarcoma and medulloblastoma), and squamous cell carcinoma of the cervix and of the head and neck. Interestingly, the subset of malignancies that are particularly sensitive to lovastatin-induced apoptosis correspond to those tumor subtypes that are sensitive to the biological and antiproliferative effects of retinoids in vitro. The nature of the biologically active form of lovastatin has been challenged recently as the growth-inhibitory effects of this drug were attributed to its prodrug lactone form that does not inhibit HMG-CoA reductase function. In this report, we demonstrate that the apoptotic properties of lovastatin are triggered by the open ring acid form that is a potent inhibitor of HMG-CoA reductase activity. Thus, we have identified a subset of tumors that are sensitive to lovastatin-induced apoptosis and show HMG-CoA reductase as a potential therapeutic target of these cancers.

Improved survival in severe acquired aplastic anemia of childhood

Multi-agent immunosuppressive therapy has produced improved survival for severe acquired aplastic anemia in children. Recently, some investigators have suggested that immunosuppressive therapy may replace bone marrow transplantation as first-line therapy for this disorder. To assess its validity, we compared the outcomes of bone marrow transplantation vs immunosuppressive therapy in one institution from 1987 to 1997. We studied 46 consecutive patients less than 18 years of age who presented between January 1987 and April 1997. Inherited marrow failure syndromes and myelodysplastic syndromes were excluded. Patients received immunosuppressive therapy vs bone marrow transplantation based on availability of HLA-matched donors. The main outcome measures were survival, complete marrow and hematological remission, or partial remission but achieving independence from transfusional support. Twenty patients received multi-agent immunosuppressive therapy (cyclosporine, antithymocyte globulin and methylprednisolone); 11 attained complete remission and three partial remission for a transfusion-independent survival of 70%. Six patients died of infectious and hemorrhagic complications. Twenty-six patients were transplanted and 24 (93%) achieved complete remission; one achieved a PR, 25 remain transfusion independent with a median follow-up of 5.9 years or 70 months. One patient developed AML 34 months after successful transplant and one patient died due to graft failure and complications of transplant. There has been a striking improvement in survival for pediatric patients treated with multi-agent immunosuppression in the last decade. However, transplantation results have also improved and this remains the definitive first-line therapy for severe acquired aplastic anemia in this age group.

Combined corticosteroid/granulocyte colony-stimulating factor (G-CSF) therapy in the treatment of severe congenital neutropenia unresponsive to G-CSF: Activated glucocorticoid receptors synergize with G-CSF signals

More than 90% of patients with severe congenital neutropenia (SCN) respond to granulocyte colony-stimulating factor (G-CSF) therapy. The basis for the refractory state in the remaining patients is unknown. To address this issue, we studied a child with SCN who was totally unresponsive to G-CSF and had a novel point mutation in the extracellular domain of the G-CSF receptor (GCSF-R). Marrow stromal support of granulopoiesis was evaluated by plating CD34(+) cells on preformed stromal layers. Nonadherent cells were harvested and assayed in clonogenic assays for granulocytic colony production. The in vitro effect of G-CSF and corticosteroids on granulopoiesis was evaluated in clonogenic assays of marrow mononuclear cells, by proliferation studies of the murine myeloid cell line 32D expressing the patient's mutated G-CSFR, and by measuring STAT5 activation in nuclear extracts from stimulated cells.Patient's stroma supported granulopoiesis derived from control marrow CD34(+) cells in a normal manner. Normal stroma, however, failed to induce granulopoiesis from patient's CD34(+) cells. Clonogenic assays of the patient's marrow mononuclear cells incorporating either G-CSF or hydrocortisone produced little neutrophil growth. In contrast, inclusion of both G-CSF and hydrocortisone in the cytokine "cocktail" markedly increased the neutrophil numbers. Proliferation of 32D cells expressing the mutated receptor and STAT5 activation were improved by a combination of G-CSF and dexamethasone. When small daily doses of oral prednisone were then administered to the patient with conventional doses of subcutaneous G-CSF, the patient responded with increased neutrophil numbers and with a complete reversal of the infectious problems. These data provide insight into SCN unresponsive to standard G-CSF treatment and to the potential corrective action of combined treatment with G-CSF and corticosteroids through synergistic activation of STAT5.

Diamond-Blackfan anaemia

Diamond-Blackfan anaemia (DBA) has had an intellectual allure for decades for clinical and experimental haematologists. The syndrome has a haematological phenotype of early-onset red-cell aplasia but is coupled with a baffling array of pleiotropy. There is discordance with modes of inheritance, physical anomalies, erythropoietic response to corticosteroid therapy, spontaneous 'remissions', and evolution to malignant myeloid transformation and to cancer. The recent discovery of two genes associated with DBA is the entry point for explaining the diversity of the phenotype and for understanding the molecular basis of the syndrome.

Myelodysplasia syndrome and acute myeloid leukemia in patients with congenital neutropenia receiving G-CSF therapy

Granulocyte colony-stimulating factor (G-CSF) has had a major impact on management of "severe chronic neutropenia," a collective term referring to congenital, idiopathic, or cyclic neutropenia. Almost all patients respond to G-CSF with increased neutrophils, reduced infections, and improved survival. Some responders with congenital neutropenia have developed myelodysplastic syndrome and acute myeloblastic leukemia (MDS/AML), which raises the question of the role of G-CSF in pathogenesis. The Severe Chronic Neutropenia International Registry (SCNIR), Seattle, WA, has data on 696 neutropenic patients, including 352 patients with congenital neutropenia, treated with G-CSF from 1987 to present. Treatment and patient demographic data were analyzed. The 352 congenital patients were observed for a mean of 6 years (range, 0.1-11 years) while being treated. Of these patients, 31 developed MDS/AML, for a crude rate of malignant transformation of nearly 9%. None of the 344 patients with idiopathic or cyclic neutropenia developed MDS/AML. Transformation was associated with acquired marrow cytogenetic clonal changes: 18 patients developed a partial or complete loss of chromosome 7, and 9 patients manifested abnormalities of chromosome 21 (usually trisomy 21). For each yearly treatment interval, the annual rate of MDS/AML development was less than 2%. No significant relationships between age at onset of MDS/AML and patient gender, G-CSF dose, or treatment duration were found (P >.15). In addition to the 31 patients who developed MDS/AML, the SCNIR also has data on 9 additional neutropenic patients whose bone marrow studies show cytogenetic clonal changes but the patients are without transformation to MDS/AML. Although our data does not support a cause-and-effect relationship between development of MDS/AML and G-CSF therapy or other patient demographics, we cannot exclude a direct contribution of G-CSF in the pathogenesis of MDS/AML. This issue is unclear because MDS/AML was not seen in cyclic or idiopathic neutropenia. Improved survival of congenital neutropenia patients receiving G-CSF therapy may allow time for the expression of the leukemic predisposition that characterizes the natural history of these disorders. However, other factors related to G-CSF may also be operative in the setting of congenital neutropenia. (Blood. 2000;96:429-436)

Thrombocytopenia with absent radii: frequency of marrow megakaryocyte progenitors, proliferative characteristics, and megakaryocyte growth and development factor responsiveness

Congenital thrombocytopenia with absent radii (TAR syndrome) is characterized by defective thrombopoiesis and bleeding in early infancy. To determine the frequency and responsiveness to cytokines of megakaryocyte progenitors (CFU-Meg) in TAR syndrome, the authors studied marrow samples from 3 patients and 6 normal controls, using optimally standardized megakaryocyte growth media incorporating interleukin-3, interleukin-6, stem cell factor, and granulocyte-monocyte colony-stimulating factor, with and without pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF). CFU-Meg was identified with a specific staining system utilizing monoclonal antibodies to glycoprotein IIb/IIIa. Growth of small CFU-Meg colonies (3-20 cells/colony) was observed in all patients in cultures without PEG-rHuMGDF, with a mean frequency of 8 (range 5-12) per 2.25 x 10(5) mononuclear cells plated (control mean 23; range 2-70). Identical cultures of marrow cells from patients and controls with added PEG-rHuMGDF produced more colonies per dish (mean 17, range 8-23; control mean 30, range 6-62). Except for 1 case, however, patients' colonies in response to PEG-rHuMGDF remained smaller than those of controls. Two patients tested had higher plasma thrombopoietin levels than 6 normal subjects. The findings demonstrate proliferative and PEG-rHuMGDF-responsive megakaryocytic progenitors in TAR syndrome. The modest reduction in frequency of megakaryocyte progenitors and the suboptimal size of colonies in response to PEG-rHuMGDF are compatible with the reported defective signal transduction in the c-mpl pathway in TAR syndrome.

Mastocytosis cells bearing a c-kit activating point mutation are characterized by hypersensitivity to stem cell factor and increased apoptosis

Mastocytosis is characterized by abnormal infiltration of mast cells into various organs. An activating mutation in c-kit, involving an A --> T substitution at nucleotide 2648 has recently been described in some patients with mastocytosis. We describe a 12-year-old girl with this mutation in her bone marrow cells at diagnosis with a myelodysplastic syndrome (MDS) without evidence of mastocytosis, and then in peripheral blood mononuclear cells 1 year later after the emergence of mastocytosis. The role of the c-Kit receptor and its ligand stem cell factor (SCF) in the pathogenesis of the disease was analysed in marrow cell clonogenic assays. We show that the genetic abnormalities in the patient resulted in factor-independent growth and hypersensitivity of primitive progenitors to SCF, with increased production of mast cells. Increased apoptosis and cluster formation, consistent with the myelodysplastic nature of the disorder, accompanied accumulation of abnormal cells with increasing concentrations of SCF.

Shwachman-Diamond syndrome: An inherited preleukemic bone marrow failure disorder with aberrant hematopoietic progenitors and faulty marrow microenvironment

Shwachman-Diamond syndrome (SD), an inherited disorder with varying cytopenias and a marked tendency for malignant myeloid transformation, is an important model for understanding genetic determinants in hematopoiesis. To define the basis for the faulty hematopoietic function, 13 patients with SD (2 of whom had myelodysplasia with a clonal cytogenetic abnormality) and 11 healthy marrow donors were studied. Patients with SD had significantly lower numbers of CD34(+) cells on bone marrow aspirates. SD CD34(+) cells plated directly in standard clonogenic assays showed markedly impaired colony production potential, underscoring an intrinsically aberrant progenitor population. To assess marrow stromal function, long-term marrow stromal cell cultures (LTCs) were established. Normal marrow CD34(+) cells were plated over either SD stroma (N/SD) or normal stroma (N/N); SD CD34(+) cells were plated over either SD stroma (SD/SD) or normal stroma (SD/N). Nonadherent cells harvested weekly from N/SD LTCs were strikingly reduced compared with N/N LTCs; numbers of granulocyte-monocyte colony-forming units (CFU-GM) derived from N/SD nonadherent cells were also lower. SD/N showed improved production of nonadherent cells and CFU-GM colonies compared with SD/SD, but much less than N/N. Stem-cell and stromal properties from the 2 patients with SD and myelodysplasia did not differ discernibly from SD patients without myelodysplasia. We conclude that in addition to a stem-cell defect, patients with SD have also a serious, generalized marrow dysfunction with an abnormal bone marrow stroma in terms of its ability to support and maintain hematopoiesis. This dual defect exists in SD with and without myelodysplasia.

Alternative donor bone marrow transplantation for children with juvenile myelomonocytic leukemia

The purpose of this study was to evaluate the outcome of children with juvenile myelomonocytic leukemia (JMML) treated with alternative donor bone marrow transplantation (BMT). Twelve consecutive patients with JMML confirmed by in vitro clonogenic assays underwent alternative donor BMT. Ten patients received pretransplant chemotherapy for one to seven cycles (cytosine arabinoside regimens). Eight underwent splenectomy before the transplant. Donors were unrelated for nine patients and partially matched related for three. Conditioning included total body irradiation for all but one patient. Graft-versus-host disease (GVHD) prophylaxis included in vitro partial T-lymphocyte depletion for five patients with cyclosporine arabinoside, and cyclosporine arabinoside and methotrexate for seven. Acute GVHD developed in all patients, and chronic GVHD developed in 7 of 11 evaluable patients. Relapses occurred in two patients, and two died of transplant-related causes. Eight patients remain in remission with a median follow-up of 31 months after the BMT. The event-free survival rate for this series is 64% (95% confidence interval, 27%-85%). The roles of pretransplant chemotherapy and splenectomy for leukemic reduction to prevent relapse, and the use of conditioning regimens with total body irradiation require study in a larger series of patients. GVHD may be beneficial in preventing relapses, which has been the major cause of treatment failure for these patients.

Juvenile myelomonocytic leukemia and Noonan syndrome

A case of juvenile myelomonocytic leukemia (JMML, previously referred to as JCML) in a neonate with Noonan syndrome (NS) is described. The boy presented with bilateral congenital hydrothoraces, nonimmune hydrops, dysmorphic facies, persistent thrombocytopenia, and leukocytosis. The diagnosis of JMML was made on bone marrow cell culture studies. Review of the literature reveals an unusual preponderance of hematologic malignancies, in particular JMML, among patients with NS. Of 40 NS patients admitted to the authors' institution during a 10-year period, there were 4 (10%) with evidence of a monocytic proliferation, which resolved spontaneously. The authors postulate that patients with NS may have an increased incidence of myeloproliferative disorders, which in most cases appears to be benign but may be preleukemic or even lethal.

p53 gene status and chemosensitivity of childhood acute lymphoblastic leukemia cells to adriamycin

The role of p53 as a determinant of sensitivity of ten childhood acute lymphoblastic leukemia (ALL) cell lines to Adriamycin (ADR) was investigated. ADR-sensitive cell lines were found to have wild-type (wt) p53, whereas resistant cell lines contained point mutations in the gene. The basal level of wt p53 protein in sensitive cells was lower than that of mutant p53 in resistant cells, however, after ADR treatment a 6- to 20-fold dose-dependent increase in wt p53 was observed, whereas mutant p53 increased only twofold. The percentage of apoptotic cells in ADR-sensitive lines with wt p53 ranged from 43 to 93% following ADR treatment, whereas that in resistant lines with mutant p53 was only 8-13%. The ratio of constitutive levels of Bax/Bcl-2 was significantly higher in cells containing wt p53 than in cells with mutant p53. These results suggest that p53 gene status and the ability of p53 to induce apoptosis may be determinants of sensitivity to ADR in childhood ALL cells.

Relative efficacy of amethocaine gel and lidocaine-prilocaine cream for Port-a-Cath puncture in children

BACKGROUND

Lidocaine-prilocaine cream (EMLA) is currently standard therapy to alleviate procedural pain in children. One of the disadvantages of lidocaine-prilocaine is the need to wait for 60 minutes for adequate skin anesthesia. Amethocaine gel (Ametop) is a new topical anesthetic that requires a shorter application time for skin anesthesia.

OBJECTIVES

To compare the relative efficacy and safety of amethocaine gel and lidocaine-prilocaine cream in children with cancer undergoing Port-a-Cath puncture and to determine which patient factors influence judgments about pain.

METHODS

Randomized, blinded, crossover study. Each child received either 1 g of amethocaine gel for 30 minutes, preceded by a placebo gel for 30 minutes, or 1 g of lidocaine-prilocaine cream for 60 minutes. Children rated the pain using the faces scale, for which scores ranged from 0 to 5. Parents and attending nurse operators rated pain on a 10-cm visual analog scale.

RESULTS

Thirty-nine children participated. The mean age was 10.2 years (range: 5-16 years), and 69% were male. There were no differences in mean pain assessments between amethocaine and lidocaine-prilocaine as rated by the children (2.0 vs 0.5), parents (2.6 vs 6.4), or nurse operators (2.0 vs 0.9). No serious adverse effects were detected with either preparation. Pain scores assigned by parents and children were not influenced by age, gender, duration of diagnosis, or anesthetic regimen (amethocaine versus lidocaine-prilocaine) in the child. Nurses, however, rated pain higher for younger children, and in males during pretreatment with lidocaine-prilocaine.

CONCLUSION

Amethocaine achieves similar anesthesia to lidocaine-prilocaine during Port-a-Cath administration in children, with an application time that is half of lidocaine-prilocaine. Pain assessments were not influenced by age, gender, or duration of diagnosis of the child. Nurses may perceive that pain is greater for younger children and in males. lidocaine-prilocaine, amethocaine, pain, children, Port-a-Cath puncture.

Novel point mutation in the extracellular domain of the granulocyte colony-stimulating factor (G-CSF) receptor in a case of severe congenital neutropenia hyporesponsive to G-CSF treatment

Severe congenital neutropenia (SCN) is a heterogeneous condition characterized by a drastic reduction in circulating neutrophils and a maturation arrest of myeloid progenitor cells in the bone marrow. Usually this condition can be successfully treated with granulocyte colony-stimulating factor (G-CSF). Here we describe the identification of a novel point mutation in the extracellular domain of the G-CSF receptor (G-CSF-R) in an SCN patient who failed to respond to G-CSF treatment. When this mutant G-CSF-R was expressed in myeloid cells, it was defective in both proliferation and survival signaling. This correlated with diminished activation of the receptor complex as determined by signal transducer and activator of transcription (STAT) activation, although activation of STAT5 was more affected than STAT3. Interestingly, the mutant receptor showed normal affinity for ligand, but a reduced number of ligand binding sites compared with the wild-type receptor. This suggests that the mutation in the extracellular domain affects ligand-receptor complex formation with severe consequences for intracellular signal transduction. Together these data add to our understanding of the mechanisms of cytokine receptor signaling, emphasize the role of GCSFR mutations in the etiology of SCN, and implicate such mutations in G-CSF hyporesponsiveness.

The morbidity and mortality of pediatric splenectomy: does prophylaxis make a difference?

PURPOSE

The aim of this study was to analyze the incidence of postsplenectomy sepsis morbidity and mortality after prophylaxis, in comparison with our previous 13-year study (1958 to 1970, inclusive).

METHODS

All patients who had splenectomy at the Hospital for Sick Children, Toronto, between 1971 and 1995, inclusive (to give a minimum of 2 years for follow-up), were reviewed for infection and mortality. The criterion for classifying a patient as "infected" was the recovery of an invading encapsulated organism from the blood culture in a patient admitted to the hospital.

RESULTS

Of the 264 patients studied, 10 had a postsplenectomy infection (3.8%); nine occurred in patients who underwent splenectomy between the ages of 0 and 5 years. Infection took place within 2 +/- 3 years (mean +/- SD) after splenectomy for the immunized patients and 11 +/- 5 days (mean +/- SD) for the nonimmunized children. A significant number of patients were admitted for an apparent respiratory infection, but no serum organisms were isolated. One died of overwhelming sepsis, but the responsible organism was not identified.

CONCLUSION

Although there has not been a decrease in the number of splenectomies performed per year, the incidence of infection and mortality has decreased by 47% and 88%, respectively, with prophylaxis.

Autocrine interleukin-1beta production in leukemia: evidence for the involvement of mutated RAS

Interleukin (IL)-1beta is constitutively expressed in many leukemias and operates as an autocrine growth factor. To study the cellular basis for this aberrant production, we analyzed two cell lines, B1 (acute lymphoblastic leukemia) and W1 (juvenile chronic myelogenous leukemia), which express high levels of IL-1beta and have mutations in the K-RAS and N-RAS genes, respectively. Electromobility shift assays demonstrated transcription factor binding at multiple IL-1beta promoter elements [nuclear factor (NF)-IL6/CREB, NFB1, NFkappaB, and NF-IL6], consistent with the activation of an upstream signaling pathway. To determine whether activated Ras was involved, two structurally distinct classes of farnesyltransferase (FTase) inhibitors (the monoterpenes and a peptidomimetic) and an adenoviral vector expressing antisense targeted to K-RAS were used to specifically interfere with Ras function and/or expression. Treatment with the FTase inhibitors resulted in a concentration-dependent decrease in both NF-IL6/CREB binding to the IL-1beta promoter and IL-1beta protein levels, without a significant change in total cellular protein levels. Furthermore, exposure of the B1 cells to antisense against K-RAS resulted in an approximately 50% reduction in both p21Ras and IL-1beta protein levels. Growth suppression was observed after FTase inhibitor or antisense exposure, an effect that was partially reversible by the addition of recombinant IL-1beta to the cultures. Our observations suggest that mutated RAS genes may mediate autocrine IL-1beta production in some leukemias by stimulating signal transduction pathways that activate the IL-1beta promoter.

Detection of residual disease in acute lymphoblastic leukemia of childhood

Several techniques developed in recent years provide us with the capability to detect sub-microscopic leukemia during remission. Quantitative polymerase chain reaction (PCR) is thus far the most sensitive assay that is applicable in most patients with acute lymphoblastic leukemia (ALL) of childhood. However, false-positive and false-negative results may provide the clinician with misleading data and therefore PCR analysis should be accompanied by another assay and changes in the level of residual disease should be confirmed at different time points following treatment. Furthermore, several studies did not determine a threshold of residual disease level above which relapse is likely to occur, and more recent data show that long-term remission may be sustained in the presence of residual disease. Thus, additional studies of the biology of residual disease in childhood ALL should be performed before sensitive assays of residual disease detection and quantitation can be clinically utilized.

Increased sensitivity of acute myeloid leukemias to lovastatin-induced apoptosis: A potential therapeutic approach

We recently demonstrated that 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, the rate-limiting enzyme of de novo cholesterol synthesis, was a potential mediator of the biological effects of retinoic acid on human neuroblastoma cells. The HMG-CoA reductase inhibitor, lovastatin, which is used extensively in the treatment of hypercholesterolemia, induced a potent apoptotic response in human neuroblastoma cells. This apoptotic response was triggered at lower concentrations and occurred more rapidly than had been previously reported in other tumor-derived cell lines, including breast and prostate carcinomas. Because of the increased sensitivity of neuroblastoma cells to lovastatin-induced apoptosis, we examined the effect of this agent on a variety of tumor cells, including leukemic cell lines and primary patient samples. Based on a variety of cytotoxicity and apoptosis assays, the 6 acute lymphocytic leukemia cell lines tested displayed a weak apoptotic response to lovastatin. In contrast, the majority of the acute myeloid leukemic cell lines (6/7) and primary cell cultures (13/22) showed significant sensitivity to lovastatin-induced apoptosis, similar to the neuroblastoma cell response. Of significance, in the acute myeloid leukemia, but not the acute lymphocytic leukemia cell lines, lovastatin-induced cytotoxicity was pronounced even at the physiological relevant concentrations of this agent. Therefore, our study suggests the evaluation of HMG-CoA reductase inhibitors as a therapeutic approach in the treatment of acute myeloid leukemia.

Long-term bone marrow cultures in Diamond-Blackfan anemia reveal a defect of both granulomacrophage and erythroid progenitors

The hematopoietic defect of Diamond-Blackfan anemia (DBA) results in selective failure of erythropoiesis. Thus far, it is not known whether this defect originates from an intrinsic impediment of hematopoietic progenitors to move forward along the erythroid pathway or to the impaired capacity of the bone marrow (BM) microenvironment to support proliferation and differentiation of hematopoietic cells. Reduced longevity of long-term bone marrow cultures, the most physiologic in vitro system to study the interactions of hematopoietic progenitors and hematopoietic microenvironment, is consistent with a defect of an early hematopoietic progenitor in DBA. However, stromal adherent layers from DBA patients generated in a long-term culture system, the in vitro counterpart of BM microenvironment, did not show evidence of any morphologic, phenotypic, or functional abnormality. Our major finding was an impaired capacity of enriched CD34+ BM cell fraction from DBA patients, cultured in the presence of normal BM stromal cells, to proliferate and differentiate along the erythroid pathway. A similar impairment was observed in some DBA patients along the granulomacrophage pathway. Our result points to an intrinsic defect of a hematopoietic progenitor with bilineage potential that is earlier than previously suspected as a relevant pathogenetic mechanism of the disease. The finding of impaired granulopoiesis in some DBA patients underlines the heterogeneity of this rare disorder.

Diphtheria toxin fused to granulocyte-macrophage colony-stimulating factor is toxic to blasts from patients with juvenile myelomonocytic leukemia and chronic myelomonocytic leukemia

We have previously demonstrated that human granulocyte-macrophage colony-stimulating factor fused to a truncated diphtheria toxin (DT388-GM-CSF) is toxic to patient acute myeloid leukemia progenitors bearing the GM-CSF receptor, but not normal marrow progenitors. We now report that exposure of mononuclear cells from five of seven (71%) juvenile myelomonocytic leukemia (JMML) patients and from 12 of 20 (60%) adult chronic myelomonocytic leukemia (CMML) patients to 10(-9) mol/L DT388-GM-CSF for 48 hours in culture reduces the number of cells capable of forming colonies in semisolid medium (colony-forming units-leukemia) 10-fold to 300-fold (1 to 2.5 log decrease). In contrast, normal myeloid progenitors (colony-forming unit-granulocyte-macrophage) from six different donors treated and assayed under identical conditions were consistently insensitive to the same fusion toxin even when treated as highly purified CD34(+) cells. The leukemic progenitors from the two other JMML patients showed intermediate sensitivity to DT388-GM-CSF and the leukemic progenitors from eight of the 20 (40%) CMML patients were not different from normal progenitors. Parallel measurements of the number and affinity of GM-CSF receptors on cells from the same samples showed no consistent differences between JMML, CMML, and normal light density or CD34(+) bone marrow cells. The increased sensitivity of leukemic progenitors from all JMML progenitors and some CMML patients to the fusion toxin is therefore not likely to be explained by an increased density of GM-CSF receptors on these cells. We also examined the DT388-GM-CSF sensitivity of two murine cell lines transfected with cDNAs encoding varying portions of the human GM-CSF receptor and/or beta chains. These studies showed that high-affinity ligand binding was sufficient for DT388-GM-CSF-induced toxicity, as this could occur even in the absence of functional signal transduction and that the background of the host cell had a major influence on the degree to which this decreased the toxicity of DT388-GM-CSF. The selective sensitivity to DT388-GM-CSF of leukemic progenitors from a majority of JMML and CMML patients suggests that this agent could have therapeutic potential for some patients with these diseases.

Malignant myeloid transformation with isochromosome 7q in Shwachman-Diamond syndrome

Shwachman-Diamond syndrome is an autosomal recessive disorder characterized by exocrine pancreatic dysfunction, bony metaphyseal dysostosis, various degrees of cytopenia, and a striking tendency to develop myelodysplastic syndrome and acute myeloblastic leukemia. Isochromosome 7 [i(7q)] is a rare non-random cytogenetic abnormality of myeloid cells in hematological malignancy. We report two cases of Shwachman-Diamond syndrome in which patients developed myelodysplastic syndrome and i(7q), detected by G-banding karyotype analysis and fluorescence in situ hybridization. Three other children have been previously reported to have myelodysplastic syndrome in association with i(7q); two of them had Shwachman-Diamond syndrome. Isochromosome 7q may be a fairly specific marker of myeloid malignant transformation in this syndrome and play a role in its pathogenesis.

Duplication of distal thumb phalanx in Shwachman-Diamond syndrome

Shwachman-Diamond syndrome (SDS) comprises of exocrine pancreatic dysfunction, various degree of pancytopenia, and metaphyseal dysplasia. We report on a child with SDS and duplication of distal thumb phalanx. This combination has not been reported previously. We suggest that supernumerary thumb is likely a rare skeletal manifestation of SDS and that SDS should be considered in the differential diagnosis of patients with bone marrow failure and duplication of the thumb along with Blackfan-Diamond/Aase syndrome and Fanconi's anemia.

P/NP, and the quantum field computer

The central problem in computer science is the conjecture that two complexity classes, P (polynomial time) and NP (nondeterministic polynomial time-roughly those decision problems for which a proposed solution can be checked in polynomial time), are distinct in the standard Turing model of computation: P not equal NP. As a generality, we propose that each physical theory supports computational models whose power is limited by the physical theory. It is well known that classical physics supports a multitude of implementation of the Turing machine. Non-Abelian topological quantum field theories exhibit the mathematical features necessary to support a model capable of solving all #P problems, a computationally intractable class, in polynomial time. Specifically, Witten [Witten, E. (1989) Commun. Math. Phys. 121, 351-391] has identified expectation values in a certain SU(2)-field theory with values of the Jones polynomial [Jones, V. (1985) Bull. Am. Math. Soc. 12, 103-111] that are #P-hard [Jaeger, F., Vertigen, D. & Welsh, D. (1990) Math. Proc. Comb. Philos. Soc. 108, 35-53]. This suggests that some physical system whose effective Lagrangian contains a non-Abelian topological term might be manipulated to serve as an analog computer capable of solving NP or even #P-hard problems in polynomial time. Defining such a system and addressing the accuracy issues inherent in preparation and measurement is a major unsolved problem.

Limit, logic, and computation

We introduce "ultrafilter limits" into the classical Turing model of computation and develop a paradigm for interpreting the problem of distinguishing the class P from NP as a logical problem of decidability. We use P(NP) to denote decision problems which can be solved on a (nondeterministic) Turing machine in polynomial time. The concept is that in an appropriate limit it may be possible to prove that problems in P are still decidable, so a problem whose limit is undecidable would be established as lying outside of P.

An improved limited sampling method for individualised busulphan dosing in bone marrow transplantation in children

Busulphan (BU) pharmacokinetic (PK) studies in children undergoing bone marrow transplantation suggest that individual BU dosing may be necessary to optimise BU systemic exposure. Optimising BU systemic exposure may improve outcome and decrease toxicity in BMT. Because of practical limitations in obtaining blood from children and for financial reasons, a limited sampling method (LSM) is needed. However, such methods for BU have not been validated in children. In the present study, we individualized oral BU dosing in 10 children to target an area under the curve of BU (BU AUC) of 900-1400 microM/min based on BU AUC(0-infinity) calculated from nine serum BU concentrations performed after a BU test dose of 40 mg/m2. We validated a LSM using 3 BU concentrations to determine AUC. Six of nine patients studied (one patient non-evaluable), required their doses modified (3, lower; 3, higher). The mean percent dose change was 26.2% (range -33.3% to +45.3%). Our three sample LSM BU AUC(0-infinity) (1098 +/- 344, mean +/- 1 s.d.) correlated highly with our nine sample BU AUC(0-infinity) (1132 +/- 389, Pearson r = 0.98, P = 0.0001) and was not significantly different by t-test (P = 0.3). The mean percentage difference between the three sample LSM AUCs and the nine sample AUCs in each of our patients was 7.5%, (range -10.99% to +9.4%). Trough levels correlated extremely well with AUC (r = 0.95, P = 0.0001). Individual BU dosing, based on AUC, is necessary in most children to achieve targeted levels of BU therapy. An LSM of three BU concentrations performed at 0.5 h, 1 h and 6 h post-BU test dose closely predicts the AUC calculated from nine sampling points.

Safety of long-term administration of granulocyte colony-stimulating factor for severe chronic neutropenia

When a new product with huge clinical potential explodes on the scene, the hope is that the benefits far outweigh the risks in long-term administration. After 10 years of clinical use, granulocyte colony-stimulating factor (G-CSF) has lived up to that promise so far. In the context of severe chronic neutropenia, more than 90% of patients have reaped big benefits in terms of improved quality of life and less infection, inflammation, antibiotic use, and hospitalization as well as oropharyngeal ulcers. With long-term use, toxic and adverse events have been catalogued but in general are not clinically troublesome and, aside from occasional adjustment of scheduling and dosing, seldom necessitate stopping therapy. Currently, the topic of intense focus is the phenomenon of malignant myeloid transformation in patients with congenital neutropenia who are receiving G-CSF. Data from the Severe Chronic Neutropenia International Registry have identified 23 of 249 patients with congenital neutropenia who have developed myelodysplasia or acute myelogenous leukemia (MDS/AML) giving a crude rate of about 9% with an average follow-up of 4.5 years. No cases of MDS/AML have occurred in 257 patients with cyclic or idiopathic neutropenia. A critical analysis of the incidence of transformation year by year showed a fairly uniform hazard rate of less than 2% per year, and the risk of MDS/AML after 5 to 6 years of therapy did not appear to be greater than during the first year of therapy. The transformation risk in the congenital cohort must also be viewed in the context of published reports of spontaneous myelodysplasia or acute myelogenous leukemia occurring in these patients in the pre-G-CSF era. Thus, the role of G-CSF in malignant conversion is still not clear and requires long-term vigilance and research. G-CSF is still deemed specific therapy for severe chronic neutropenia with a high margin of safety and should be the initial treatment for this family of disorders.

Shwachman syndrome: exocrine pancreatic dysfunction and variable phenotypic expression

BACKGROUND & AIMS

Shwachman syndrome is an inherited condition with multisystemic abnormalities, including exocrine pancreatic dysfunction. The aim of this study was to evaluate the occurrence and progression of features in a large cohort of patients.

METHODS

Clinical records of 25 patients with Shwachman syndrome were reviewed.

RESULTS

Mean birth weight (2.92 +/- 0.51 kg) was at the 25th percentile. However, by 6 months of age, mean heights and weights were less than the 5th percentile. After 6 months of age, growth velocity was normal. Severe fat maldigestion due to pancreatic insufficiency was present in early life (fecal fat, 26% +/- 17% of fat intake; age, < 2 years). Serial assessment of exocrine pancreatic function showed persistent deficits of enzyme secretion, but 45% of patients showed moderate age-related improvements leading to pancreatic sufficiency. Neutropenia was the most common hematologic abnormality (88%), but leukopenia, thrombocytopenia, and anemia were also frequently encountered. Patients with hypoplasia of all three bone marrow cellular lines (n = 11) had the worst prognosis; 5 patients died, 2 of sepsis and 3 of acute myelogenous leukemia. Other findings included hepatomegaly and/or abnormal liver function test results and skeletal abnormalities.

CONCLUSIONS

A wide and varied spectrum of phenotypic abnormalities among patients with Shwachman syndrome is described. Pancreatic acinar dysfunction is an invariable abnormality. Patients with severe bone marrow involvement may have a guarded prognosis.

Patterns of hematopoietic lineage involvement in children with neurofibromatosis type 1 and malignant myeloid disorders

Children with neurofibromatosis type 1 (NF1) are at increased risk of developing malignant myeloid disorders, particularly juvenile chronic myelogenous leukemia/juvenile myelomonocytic leukemia (JCML/JMML). We investigated bone marrows from 11 such patients (8 boys and 3 girls) and detected allelic losses at the NF1 locus in 4 of them and probable losses in 2 others. To determine which hematopoietic cell lineages were derived from the abnormal clones, Epstein-Barr virus (EBV)-transformed cell lines and CD34+ cells were analyzed from 3 children with JCML with allelic losses in unfractionated marrow. CD34 cells from these 3 patients lacked the normal NF1 allele, whereas EBV cell lines retained it. Erythroblasts plucked from the burst-forming unit-erythroid colonies of one of these children lacked the normal NF1 allele. We also studied a 10-month-old boy with NF1 who developed an unusual myeloproliferative syndrome. His bone marrow and EBV cell line both showed loss of the normal NF1 allele. In our series and in the literature, male sex and maternal transmission of NF1 were associated with the highest risk of myeloid leukemia. These data (1) provide strong genetic evidence that NF1 functions as a tumor-suppressor in early myelopoiesis, (2) confirm the clonal nature of JCML/JMML, (3) suggest that the elevation in fetal hemoglobin seen in JCML/JMML is a result of primary involvement of erythroid progenitors in the malignant clone, (4) show consistent loss of NF1 in the CD34 cells of affected children and show that the malignant clone may also give rise to pre-B cells in some cases, and (5) implicate epigenetic factors in the development of leukemia in children with NF1.

Juvenile chronic myelogenous leukemia multilineage CD34+ cells: aberrant growth and differentiation properties

Juvenile chronic myelogenous leukemia (JCML) is a hematologic malignancy of monocyte-macrophage lineage in which leukemic progression is mediated in an autocrine manner by tumor necrosis factor (TNF-alpha), GM-CSF and possibly other growth factors. Cytogenetic data showing involvement of both erythroid and monocyte-macrophage lineages in the JCML leukemic clone, as well as an observed episode of B-lineage lymphoid blast crisis in JCML, has strengthened the thesis for a lympho-hematopoietic pluripotent stem cell origin for the disorder. To study this further, JCML CD34+ cells from bone marrow (BM) or spleen from six newly diagnosed patients were isolated and cultured in clonogenic assays with combinations of recombinant cytokines. Compared to control CD34+ cells, JCML cells from all patients showed an aberrant growth pattern restricted almost exclusively to the monocyte-macrophage lineage. Most of the clonogenic activity was seen in a subsorted population of CD34+, HLA-Dr- cells. Additionally, an exaggerated growth response to minute doses of GM-CSF that had no effect on control cells was observed with JCML CD34+ cells. Recloning ("self-renewal") of JCML CD34+ cells was also strongly promoted by GM-CSF. JCML colonies also formed spontaneously in the absence of exogenous cytokines but were augmented by GM-CSF, interleukin 1 and TNF-alpha, the latter feature not seen with control CD34+ cells from normal BM. The abnormal spontaneous growth pattern of CD34+ JCML cells could be suppressed directly in vitro by anti-TNF-alpha antibodies and anti-GM-CSF antibodies alone or in combination, and by soluble TNF-alpha receptors (sTNF-R:Fc), consistent with the notion that JCML CD34+ cells are stimulated by both cytokines in an autocrine manner. In malignant CD34+ cells from one patient, the cytogenetic marker monosomy 7 proved leukemic involvement of monocyte-macrophage, erythroid and B-lymphoid lineages. We conclude that CD34+ JCML cells of multilineage potential exhibit excessive and aberrant monocyte-macrophage colony formation, a property that was previously observed in JCML progenitors found in light density cell fractions. Thus, within the CD34+ cellular compartment is a subpopulation of JCML "stem" cells that accounts for the abnormal leukemic proliferative activity in this disease.

Identification of human juvenile chronic myelogenous leukemia stem cells capable of initiating the disease in primary and secondary SCID mice

Most juvenile chronic myelogenous leukemia (JCML) cells have limited long-term proliferative capacity, and only a minority of immature cells give rise to colonies in semisolid cultures. Clonogenic JCML progenitors cannot be maintained in culture because they differentiate, and within a few weeks the leukemic clone is lost. This makes it difficult to identify the cell that initiates and maintains the disease in patients. To determine the proliferative capacity of JCML cells in vivo, bone marrow (BM), peripheral blood, or spleen cells from eight patients with JCML either at diagnosis or during treatment were transplanted into sublethally irradiated severe combined immune deficient (SCID) mice. JCML cells from all patients homed to the murine BM and proliferated extensively in response to exogenous stimulation with granulocyte-macrophage colony-stimulating factor. Within a few weeks, highly engrafted mice became ill and cachectic due to infiltration of leukemic cells and secretion of tumor necrosis factor-alpha. Murine BM, spleen, and liver were infiltrated with leukemic blasts, and typical JCML colony-forming progenitors could be recovered. Kinetic experiments demonstrated that only a small minority of transplanted cells homed to the murine BM, and that these cells initiated and maintained the disease in vivo by extensive proliferation and differentiation. To characterize the cell-surface phenotype of the JCML initiating cell (JCML-IC), JCML blood or spleen cells were fractionated on the basis of CD34/CD38 marker expression and transplanted into SCID mice. Only immature CD34+ cells could initiate the disease, while mature CD34- cells did not engraft. Within the CD34+ compartment, there was enrichment for JCML-ICs by immature cells with a CD34+/CD38- stem-cell-like phenotype. Mice transplanted with more mature CD34+/CD38+ populations that also contained clonogenic JCML progenitors were poorly engrafted. These results indicate that the JCML-IC is an earlier stage of development than clonogenic JCML progenitors. Additional evidence that the JCML-IC has stem-cell properties comes from secondary transplant experiments that test the self-renewal capacity. The JCML-IC from all three patients tested could successfully reinitiate the disease in secondary murine recipients. Thus, we have developed a functional in vivo model that replicates many aspects of human JCML, and have used this model to identify and characterize JCML-ICs and their stem-cell properties.

Prolonged administration of granulocyte colony-stimulating factor (filgrastim) to patients with Fanconi anemia: a pilot study

This report examines the effect of filgrastim (granulocyte colony-stimulating factor, [G-CSF] in 12 patients with neutropenia [absolute neutrophil count [ANC] < 1,000/mm3]) caused by Fanconi anemia (FA). Two of 14 patients who were evaluated for study entry were ineligible because of unsuspected cytogenetic abnormalities in their bone marrow (BM). G-CSF was started at 5 micrograms/kg/d. All patients had an increase in their ANC at week 8 (mean increase = 15,664/mm3). The median ANC during therapy was 5,030/mm3. Eight of 10 patients who completed 40 weeks on study maintained an ANC > 1,500/mm3 on G-CSF given every-otherday. Four patients had an increase in their platelet count by week 8 without transfusion (maximum increase = 23,000 to 45,000/mm3); however, platelet counts fell toward baseline levels as the G-CSF dose was reduced. BM CFU-MK were increased at week 8 in three of four evaluable patients. Four patients who did not receive red blood cell transfusions had an increase in their hemoglobin level of at least 2.0 g/dL. A fifth patient had a red blood cell transfusion in week 2 and then had a similar increase in hemoglobin level without subsequent transfusion. Eight of 10 patients who completed 40 weeks of treatment showed increases in the percentage of BM CD34+ cells measured by flow cytometry. The same proportion showed increases in peripheral blood CD34+ cells. Increased BM cellularity and myeloid hyperplasia were constant findings and were associated with increased expression of the proliferating cell nuclear antigen. Adverse experiences were mild fever (1 patient) and a new BM cytogenetic abnormality at week 40 (1 patient). This study shows that prolonged administration of G-CSF exerts a stimulatory effect on the BM of FA patients and may be used to maintain a clinically adequate ANC in these patients. G-CSF has beneficial effects on multiple hematopoietic lineages in some patients and may be a good candidate for use in combination cytokine protocols for FA patients with progressive aplastic anemia. G-CSF use results in an increase in circulating CD34+ cells, a finding with important implications for future gene transfer protocols.

Administration of recombinant human granulocyte-macrophage colony-stimulating factor after autologous bone marrow transplantation in children with acute myelogenous leukemia: a note of caution

A series of 22 consecutive pediatric patients undergoing ABMT for treatment of primary AML was reviewed in an efficacy analysis of recombinant human granulocytemacrophage colony-stimulating factor (rhGM-CSF). Treatment with at least two cycles of chemotherapy and a standard conditioning regimen of busulfan and cyclophosphamide preceded the marrow infusion. Twelve patients who underwent transplants between 1992 and 1994 received 5.5 micrograms/kg/day rhGM-CSF as part of their transplant protocol. They were compared with 10 patients who underwent transplants between 1989 and 1991 but did not receive rhGM-CSF. Despite containing a significantly higher proportion of patients in first clinical remission at the time of the transplant, the rhGM-CSF-treated group had a significantly higher relapse and poorer overall survival rate after ABMT than the untreated group (36 vs 90%). The rhGM-CSF-treated group tended to have more rapid neutrophil engraftment and shorter hospital stays; however, neither of these trends was statistically significant. To properly determine the role of rhGM-CSF in the survival of pediatric patients undergoing ABMT for treatment of AML, a prospective randomized trial is desirable. Until these data are available, the current analysis suggests that particular caution is indicated with the use of this drug in this group of patients.

Inactivation of Fac in mice produces inducible chromosomal instability and reduced fertility reminiscent of Fanconi anaemia

Fanconi anaemia (FA) is an autosomal recessive disease characterized by bone marrow failure, variable congenital malformations and predisposition to malignancies. Cells derived from FA patients show elevated levels of chromosomal breakage and an increased sensitivity to bifunctional alkylating agents such as mitomycin C (MMC) and diepoxybutane (DEB). Five complementation groups have been identified by somatic cell methods, and we have cloned the gene defective in group C (FAC)(7). To understand the in vivo role of this gene, we have disrupted murine Fac and generated mice homozygous for the targeted allele. The -/- mice did not exhibit developmental abnormalities nor haematologic defects up to 9 months of age. However, their spleen cells had dramatically increased numbers of chromosomal aberrations in response to MMC and DEB. Homozygous male and female mice also had compromised gametogenesis, leading to markedly impaired fertility, a characteristic of FA patients. Thus, inactivation of Fac replicates some of the features of the human disease.

Loss of NF1 results in activation of the Ras signaling pathway and leads to aberrant growth in haematopoietic cells

Individuals with neurofibromatosis type 1 (NF1) are predisposed to certain cancers including juvenile chronic myelogenous leukaemia (JCML). The NF1 tumour-suppressor gene encodes a protein (neurofibromin) that accelerates GTP hydrolysis on Ras proteins. Here we show that primary leukaemic cells from children with NF1 show a selective decrease in NF1-like GTPase activating protein (GAP) activity for Ras but retain normal cellular GAP activity. Leukaemic cells also show an elevated percentage of Ras in the GTP-bound conformation. JCML cells are hypersensitive to granulocyte-macrophage colony stimulating factor (GM-CSF), and we observed a similar pattern of aberrant growth in haematopoietic cells from Nf1-/- mouse embryos. These data define a specific role for neurofibromin in negatively regulating GM-CSF signaling through Ras in haematopoietic cells and they suggest that hypersensitivity to GM-CSF may be a primary event in the development of JCML.

Phase III randomized, double-blind placebo-controlled trial of rhGM-CSF following allogeneic bone marrow transplantation

Preliminary studies in allogeneic BMT suggest that recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) is well tolerated. This is a prospective, multicenter, randomized, double-blind, placebo-controlled trial. Yeast-derived rhGM-CSF 250 micrograms/m2/day or placebo was administered by 4-hour i.v. infusion starting on the day of marrow infusion (day 0) to day 20. All patients received HLA-identical sibling marrow and cyclosporine and prednisone for GVHD prophylaxis. Fifty three patients received rhGM-CSF and 56 received placebo. Comparison of demographics revealed no differences. The time to achieve an absolute neutrophil count of > 0.5 x 10(9) cells/l was shortened in rhGM-CSF treated patients (day 13 vs. 17, P = 0.0001). The incidences of grade III-IV mucositis and infection were significantly reduced (P = 0.005, P = 0.001, respectively) and duration of hospitalization was modestly shortened by 1 day (P = 0.02) in rhGM-CSF treated patients. No differences in platelet recovery, erythrocyte recovery, incidence of veno-occlusive disease, GVHD severity, relapse or survival were observed. In conclusion, rhGM-CSF is well tolerated and reduces post-transplant morbidity in patients undergoing HLA-identical allogeneic BMT.

B-lineage lymphoid blast crisis in juvenile chronic myelogenous leukemia: II. Interleukin-1-mediated autocrine growth regulation of the lymphoblasts

A pre-B acute lymphoblastic leukemia (ALL) cell line with monosomy 7 was established from a child with juvenile chronic myelogenous leukemia (JCML) in lymphoid blast crisis. Analysis of the growth properties of the cell line, termed 'W1' showed an interleukin-1 (IL-1) mediated autocrine pattern of cell proliferation with the following features: W1 colony growth without added growth factor was density-dependent and colony growth was augmented with serum-free autologous cell culture supernatant; exogenous IL-1 beta had a growth-promoting effect on W1 colony numbers when cells were seeded at low density; W1 cells constitutively expressed mRNA for IL-1 beta, and high levels of IL-1 beta were measured in W1 cell lysates; anti-IL-1 beta antibodies as well as IL-1 receptor antagonist markedly suppressed W1 colony growth when either was added to cultures of cells seeded without growth factors at low density; anti-GM-CSF antibodies and anti-IL-3 antibodies had no inhibitory effect on W1 colony growth. Whereas W1 colony growth was also augmented by adding IL-3, IL-4, IL-6, IL-7, GM-CSF, Steel factor and erythropoietin individually to the cultures, W1 cells did not constitutively express mRNA for any of these cytokines. W1 colony growth was markedly suppressed by exogenous TNF-alpha which contrasts sharply with the autocrine growth promoting effect of TNF-alpha on myelomonocytic elements of JCML in 'chronic' phase. The inhibitory effect of TNF-alpha on W1 cells was not due to downregulation of IL-1 production. The IL-1-dependent growth of W1 cells appeared to be unique because none of five other pre-B lineage ALL cell lines established as controls showed an autocrine growth loop via IL-1. W1 cells provide a valuable opportunity to examine the relationship of monosomy 7, B-lineage acute lymphoblastic leukemia, aberrant genetic expression of cytokines and their receptors, and IL-1 mediated autocrine cell growth in cancer.