Biomedical subjects

Melvin H Freedman

Publications and source records attributed to Melvin H Freedman.

At least 19 recordsLinked to original sources

PubMed2006

Shwachman-Diamond syndrome: an inherited model of aplastic anaemia with accelerated angiogenesis.

Bone marrow angiogenesis is increased in myelodysplastic syndromes (MDS) and acute myeloid leukaemia (AML), but has not been studied in inherited or acquired marrow failure syndromes. Shwachman-Diamond syndrome (SDS) carries a high risk of MDS/AML and is characterised by marrow stromal dysfunction. Compared with controls, SDS patients without MDS/AML had higher marrow microvessel density. Stromal VEGF gene expression, stromal vascular endothelial growth factor (VEGF) secretion and VEGF levels in serum and marrow mononuclear cells were normal. Future studies should investigate the mechanism for increased angiogenesis in SDS, and whether SDS marrow, with its increased angiogenesis, promotes progression of malignant clones.

Abnormalities, Multiple↗

PubMed2005

Mutation analysis of SBDS in pediatric acute myeloblastic leukemia.

BACKGROUND: Shwachman-Diamond syndrome (SDS) is associated with a high risk of myelodysplasia, acute myeloid leukemia (AML), and chromosome 7 abnormalities. Ninety percent of SDS patients have mutations in SBDS on 7q11. Herein, we studied the role of genetic alterations in SBDS in AML. PROCEDURE: DNA was extracted from marrows of SDS patients with AML, as well as from children with de novo AML. Direct sequencing of PCR amplified genomic DNA was performed using specific primers flanking each exon. To study whether SBDS heterozygosity confers a risk for MDS/AML, data on family members of SDS patients on the Canadian Inherited Marrow Failure Registry (CIMFR) was analyzed. RESULTS: Of two SDS patients with SDS/AML one was homozygous 258 + 2T > C, and one was compound heterozygous 183-184TA > CT/258 + 2T > C. To determine whether a subset of patients with SDS can present with AML, we analyzed 48 AML samples at remission, but no mutations were identified. To address whether acquired mutated SBDS gene is associated with leukemic transformation in de novo AML, we analyzed 77 AML samples at diagnosis or relapse (4 with -7 and 7q-) for SBDS mutations; no alterations were detected. Also, among the relatives of an SDS patient cohort on the registry no cases of MDS/AML were reported. CONCLUSIONS: Common mutations occurred in our SDS patients who develop AML, and thus, AML is not confined to a rare genetic subgroup of SDS. Newly diagnosed patients with AML are unlikely to have an underlying undiagnosed SDS. Acquired SBDS gene mutations also would appear unlikely to play a mechanistic role in de novo AML, and might not be involved in the pathogenesis of chromosome 7 abnormalities as well.

Bone Marrow Diseases↗

PubMed2005

Adenovirus-mediated p53 gene therapy in pediatric soft-tissue sarcoma cell lines: sensitization to cisplatin and doxorubicin.

Sarcomas, or tumors of connective tissue, represent roughly 20% of childhood cancers. Although the cure rate for sarcomas in general has significantly improved in the last 10 years, there continue to be subgroups that are difficult to treat. High-grade or metastatic soft-tissue sarcomas and rhabdomyosarcomas (RMS) of the extremities remain therapeutic challenges and their prognosis is often poor. The future of sarcoma therapy will likely include molecular approaches including gene/protein expression profiling and gene-based therapy. Most sarcomas harbor defects in the p53 or pRb pathways. The tumor suppressor p53 is central to regulation of cell growth and tumor suppression and restoring wild-type p53 function in pediatric sarcomas may be of therapeutic benefit. Studies with adenoviral-mediated p53 gene transfer have been conducted in many cancer types including cervical, ovarian, prostatic and head and neck tumors. Studies of this approach, however, remain limited in pediatric cancers, including sarcomas. Using three viral constructs containing cDNA for wild-type p53, mutant p53 (C135S) and lacZ, we studied the effect of adenoviral-mediated gene therapy in four pediatric sarcoma cell lines, RD and Rh4 (RMS), Rh1 (Ewing's sarcoma) and A204 (undifferentiated sarcoma). Using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) 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. Cells treated with Ad-wtp53 show upregulation of the p53 downstream targets, p21(CIP1/WAF1) and bax. Growth curves demonstrate suppression of cell growth over a period of 4 days and cells treated with Ad-wtp53 demonstrate a significant increase in sensitivity to the chemotherapeutic agents, cisplatin and doxorubicin. Our results indicate that restoration of wild-type p53 function in pediatric sarcoma cells could provide a basis for novel approaches to treatment of this disease.

Adenoviridae↗

PubMed2005

A basic classification and a comprehensive examination of pediatric myeloproliferative syndromes.

Myeloproliferative syndromes (MPSs) are clonal stem cell disorders resulting in excessive proliferation of one or more cell lineages. Since MPSs in children occur much less commonly than adults, one can argue that the biology and the categories of the various pediatric MPSs seem to be different from adults. Furthermore, confusion exists between pediatric MPS and other overlapping conditions, such as myelodysplastic syndrome. The authors' objectives were to develop a classification system with a list of disorders relevant to children and to characterize pediatric cases of MPS that were devised according to this classification. Based on the predominant proliferating cell lineage, the authors established a classification system for childhood MPS. Primary MPS was classified into granulocytic proliferation--chronic myelogenous leukemia (CML); monocytic--juvenile myelomonocytic leukemia (JMML); megakaryocytic--essential thrombocythemia (ET), familial thrombocytosis, transient myeloproliferative disorder of Down syndrome (TMD); erythrocytic--polycythemia vera, familial erythrocytosis; fibroblastic--idiopathic myelofibrosis (IMF); eosinophilic--idiopathic hypereosinophilic syndrome (IHES); and mast cells--mastocytosis. Secondary MPS was classified as non-clonal proliferation (eg, infections, drugs, toxins, autoimmune, non-hematologic neoplasm, and trauma), and these were excluded from the study. Next, the classification system was applied to the patient population at the authors' institution. One hundred two cases with primary MPS were identified between 1970 and 2001. Patients were evaluated for clinical manifestations, blood and bone marrow parameters, cytogenetics, and survival following different treatment modalities. Significant proportions of cases of childhood MPS (60%) were unique to the pediatric population and not seen in adults. The most common disorders were JMML (n = 31), TMD of Down syndrome (n = 30), and CML (n = 30); the other disorders were rare: four cases of ET, two of IMF, two of IHES, two of mastocytosis, and one primary erythrocytosis. In contrast to adults, MPS in children is more frequently treated with hematopoietic stem cell transplantation (HSCT), the only available curative option for most of these diseases. HSCT was particularly successful in the more recent cases due to more advanced techniques for HSCT. The authors found that all the cases could be easily classified. MPS in children is different from adult-type MPS in terms of biology, categories, classification, and prognosis.

Adolescent↗

PubMed2004

Purine nucleoside phosphorylase deficiency associated with a dysplastic marrow morphology.

Purine nucleoside phosphorylase (PNP) deficiency is an autosomal recessive metabolic disorder characterized by severe combined immunodeficiency and by complex neurologic symptomatology including ataxia, developmental delay, and spasticity. Herein we report severe marrow dysplasia in a patient with PNP deficiency. Drug-related marrow dysfunction was unlikely, and marrow virological studies were negative. A preleukemic myelodysplastic syndrome was also unlikely due to normal marrow CD34+ cells, colony growth in clonogenic assay of marrow mononuclear cells, apoptosis rate, and Fas expression on marrow nucleated cells, as well as morphologic improvement of the marrow dysplasia after normal red blood cell transfusion. The patient's marrow stroma showed hypersensitivity to irradiation and undetectable PNP enzyme activity similar to peripheral lymphocytes. This is the first report of PNP deficiency associated with increased lymphocyte and marrow stromal sensitivity to irradiation. We conclude that marrows from patients with PNP deficiency might have hypersensitivity to irradiation and can develop dysplastic morphology, caused either directly or indirectly by the inherited enzymatic defect.

Antigens, CD34↗

PubMed2004

Clostridium septicum myonecrosis in congenital neutropenia.

Severe congenital neutropenia (SCN) and Clostridium septicum myonecrosis is an uncommon and life-threatening association requiring urgent combined aggressive medical and surgical management. We report 2 cases of SCN (1 with known Kostmann's syndrome and 1 not known at presentation to have a congenital neutropenic disorder but subsequently received a diagnosis of cyclic neutropenia) who presented with spontaneous C septicum myonecrosis. The cases highlight the importance of response to recombinant human granulocyte colony-stimulating factor in obtaining a satisfactory outcome for these patients. Early, empirical use of recombinant human granulocyte colony-stimulating factor in patients who are suspected of having a congenital neutropenia and who present with life-threatening sepsis is recommended.

Child, Preschool↗

PubMed2003

Severe chronic neutropenia: treatment and follow-up of patients in the Severe Chronic Neutropenia International Registry.

Severe chronic neutropenia (SCN) is defined as an absolute neutrophil (ANC) of less than 0.5 x 10(9)/L, lasting for months or years. Congenital, cyclic, and idiopathic neutropenia are principal categories of SCN. Since 1994, the Severe Chronic Neutropenia International Registry (SCNIR) has collected data to monitor the clinical course, treatments, and disease outcomes for SCN patients. This report summarizes data for 853 patients, almost all treated with daily or alternate-day recombinant human granulocyte colony-stimulating factor (G-CSF or Filgrastim). G-CSF treatment increased the ANC overall from 0.34 x 10(9)/L +/- 0.018 pre-treatment to 3.70 x 10(9)/L +/- 0.18 during the first year of treatment. For most patients, the responses were durable with patients remaining on the same dose of G-CSF for many years. Long-term hematological observations showed stable mean leukocyte and neutrophil counts and gradually increasing hemoglobin levels. Thrombocytopenia developed in 4% of patients. As of January 1, 2000, myelodysplasia (MDS) or acute myelogenous leukemia (AML) has occurred in 35 of 387 patients with congenital neutropenia with a cumulative risk of 13% after 8 years of G-CSF treatment. This event occurred without a predictable relationship to the duration or dose of G-CSF treatment. No patients with cyclic or idiopathic neutropenia developed MDS or AML. Other important adverse events included hepatomegaly, osteoporosis, vasculitis, glomerulonephritis, and deaths in 4 of 14 cases requiring splenectomy. Growth and development and the outcome of pregnancy appeared to be unaffected by G-CSF treatment. These data indicate that congenital, cyclic, and idiopathic neutropenia can be effectively treated with long-term G-CSF. The risk of leukemia, osteoporosis, other potentially adverse events, and pregnancy outcome need to be further evaluated with continuing long-term observations.

Adolescent↗

PubMed2003

Mutant p53 in bone marrow stromal cells increases VEGF expression and supports leukemia cell growth.

OBJECTIVE: Genetic alterations, including p53 mutations, have been identified in the stroma of solid tumors and are thought be involved in the induction of tumor growth and metastasis. We tested the hypothesis that somatic molecular alterations in bone marrow stromal cells provide a favorable growth environment for leukemic cells. MATERIALS AND METHODS: We established an in vitro model consisting of stroma expressing mutant p53 (Cys135Ser) to study its ability to support growth of cells from a pre-B acute lymphoblastic leukemia (ALL) cell line. Normal and leukemic bone marrow stromal cells were screened for p53 mutations by mutant-specific ELISA, SSCP, and direct sequencing. Secretion of vascular endothelial growth factor (VEGF) was measured by quantitative ELISA. RESULTS: Transfection of stromal cells with mutant p53 increased synthesis of VEGF and supported the growth of leukemic cells. An ELISA-based assay suggested the occurrence of in vivo p53 alterations in bone marrow stromal cells from 2 of 12 ALL patients screened. Direct sequencing of one of these samples revealed a somatic heterozygous p53 gene mutation (Asp49His). This sample secreted more VEGF and provided increased growth support to leukemic cells. The ability of Asp 49His-p53 to increase the expression of VEGF was confirmed with transfection experiments in a p53-null cell line. CONCLUSION: Our findings indicate that genetic alterations, such as p53 mutations, in stromal cells can increase stromal-derived support of leukemia growth. Increased synthesis of pro-angiogenic cytokines, such as VEGF, may constitute one possible pathway by which this process is mediated.

Amino Acid Substitution↗

PubMed2003

The evolution of juvenile myelomonocytic leukemia in a female patient with paternally inherited neurofibromatosis type 1.

The most common myeloid malignancy seen in children with neurofibromatosis type 1 (NF-1) is juvenile myelomonocytic leukemia (JMML), a myeloproliferative disease. The vast majority of these children have inherited the neurocutaneous disease from an affected mother; boys are more often affected than girls. We present the rare finding of a 7-year-old girl with NF-1 who developed JMML. She inherited her NF-1 from the father. At the time of her initial presentation, clonogenic assays of bone marrow mononuclear cells did not show the spontaneous growth of granulocyte-macrophage colony-forming units or hypersensitivity to granulocyte-macrophage colony-stimulating factor that is characteristic of this disorder. After 1 month, repeat evaluations of the patient's clinical and laboratory test results became fully consistent with those for a diagnosis of JMML. This illustrates the stepwise evolution of this myeloproliferative disorder in NF-1 and the importance of close follow-up and reassessment of these patients. Our case is only the second report of JMML in a girl who inherited NF-1 from her father.

Bone Marrow↗

PubMed2003

Sustained cyclosporine-induced erythropoietic response in identical male twins with diamond-blackfan anemia.

After failing a trial of corticosteroid therapy, molecularly proven identical twins were treated for transfusion-dependent Diamond-Blackfan anemia with cyclosporine A, resulting in a robust erythropoietic response and a reversal of anemia. Clonogenic assays of marrow hematopoietic progenitors from both patients showed exuberant growth of BFU-E colonies but absent CFU-E. Clinically, the response has been sustained, and both patients have continued cyclosporine therapy and have been transfusion-independent for more than 27 months.

Anemia, Diamond-Blackfan↗

PubMed2002

Comparison of DR5 and Fas expression levels relative to the chemosensitivity of acute lymphoblastic leukemia cell lines.

The relationship between p53 gene status and the expression of DR5 and Fas was evaluated as a function of sensitivity of 11 acute lymphoblastic leukemia cell lines to adriamycin, etoposide, vincristine, methotrexate and dexamethasone. There was up to a 37-fold increase in expression of DR5 following treatment with ADR or VP-16 only in cells with wt p53. A direct correlation was observed between enhanced DR5 expression and sensitivity to ADR and VP-16. There was no induction of DR5 following treatment with VCR, MTX or DEX. There was up to a 51-fold increase in the median level of expression of Fas following treatment with ADR and VP-16, and unlike DR5 this occurred in cells with either wild-type or mutant p53. Nevertheless, a direct correlation was observed between Fas expression and drug-sensitivity. Conversely, there was only a two-fold increase in expression of Fas after exposure to VCR, MTX and DEX. These findings suggest that DR5 mediates sensitivity to ADR and VP-16 in a p53-dependent manner, whereas, Fas appears to mediate sensitivity to these two drugs independent of p53 status. DR5 and Fas do not appear to play a major role as determinants of chemosensitivity to VCR, MTX and DEX.

Doxorubicin↗

PubMed2002

Clonal evolution in marrows of patients with Shwachman-Diamond syndrome: a prospective 5-year follow-up study.

OBJECTIVES: Shwachman-Diamond syndrome (SDS) is characterized by varying degrees of marrow failure. Retrospective studies suggested a high propensity for malignant myeloid transformation into myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). The study's aims were to determine the cellular and molecular characteristics as well as the clinical course of malignant myeloid transformation and clonal marrow disease in patients with SDS. METHODS: This is a longitudinal prospective study of 14 patients recruited for annual hematological evaluations. Results of baseline and serial hematological assessments for up to 5 years are reported. RESULTS: Clonal marrow cytogenetic abnormalities (CMCA) were detected in 4 patients (29%) on first testing or at follow-up. The abnormalities were del(20q) in two patients, i(7q) in one, and combined del(20q) and i(7q) in one. The following tests did not distinguish patients with CMCA from other SDS patients: severity of peripheral cytopenia, fetal hemoglobin levels, percentage of marrow CD34+ cells, colony growth from marrow CD34+ cells, cluster-to-colony ratio, marrow stromal function, percentage of marrow apoptosis cells, and granulocyte colony-stimulating factor receptor expression. RAS and p53 mutation analysis and AML blast colony assays were uniformly negative. No patients showed progression into more advanced stages of MDS or into AML. In one patient, the abnormal clone became undetectable after 2 years of follow-up. CONCLUSIONS: We conclude that although CMCA in SDS is high, progression into advanced stages of MDS or to overt AML may be slow and difficult to predict. Treatment should be cautious since some abnormal clones can regress.

Acute Disease↗

PubMed2002

Abnormal telomere shortening in leucocytes of children with Shwachman-Diamond syndrome.

Haemopoietic dysfunction, ranging from single-lineage cytopenia to severe aplasia and/or myelodysplasia (MDS), is prominent in Shwachman-Diamond syndrome (SDS). To assess haemopoietic stem cell proliferation in SDS, we compared leucocyte telomere length in 12 patients with SDS to that of 41 controls, using an in-gel hybridization technique. SDS patients had an age-adjusted mean telomere length 1.4 kilobase pairs (kbp) shorter than controls (P < 0.0001). Patients with'non-severe' SDS (one- or two-lineage cytopenias; no MDS) had shortened telomeres (-1.4 kbp; P = 0.0004), as did those with 'severe' SDS. We conclude that stem cell hyperproliferation is a feature of SDS from its outset.

Adolescent↗

PubMed2002

Shwachman-diamond syndrome.

Explore the source record for details and available documents.

Exocrine Pancreatic Insufficiency↗

PubMed2002

Risk of myelodysplastic syndrome and acute myeloid leukemia in congenital neutropenias.

Granulocyte colony-stimulating factor (G-CSF) has had a major impact on the management of "severe chronic neutropenia" (SCN), 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 and Shwachman-Diamond syndrome (SDS) have developed myelodysplastic syndrome and acute myeloid leukemia (MDS/AML), which raises the question of the role of G-CSF in pathogenesis. The issue is complicated because both disorders have a propensity for MDS or AML as part of their natural history. To address this, the Severe Chronic Neutropenia International Registry (SCNIR) used its large database of chronic neutropenia patients treated with G-CSF to determine the incidence of malignant myeloid transformation in the two disorders, and its relationship to treatment and to other patient characteristics. No statistically significant relationships were found between age at onset of MDS or AML and patient gender, G-CSF dose, or duration of G-CSF therapy. What was observed, however, was the multistep acquisition of aberrant cellular genetic changes in marrow cells from patients who transformed, including activating ras oncogene mutations, clonal cytogenetic abnormalities, and G-CSF receptor mutations. In murine models, the latter produces a hyperproliferative response to G-CSF, confers resistance to apoptosis, and enhances cell survival. Since congenital neutropenia and SDS are inherited forms of bone marrow failure, G-CSF may accelerate the propensity for MDS/AML in the genetically altered stem and progenitor cells, especially in those with G-CSF receptor and ras mutations (82% and 50% of patients who transform, respectively). Alternatively, and equally plausible, G-CSF may simply be an "innocent bystander" that corrects neutropenia, prolongs patient survival, and allows time for the malignant predisposition to declare itself. In patients who transform to overt MDS or AML, hematopoietic stem cell transplantation is the only chance for cure. In those with "soft" signs of MDS, such as an isolated clonal cytogenetic change but without other evidence of MDS, or with an isolated G-CSF receptor mutation, there is room for conservative management. One option is to reduce the G-CSF dosage as much as possible, and observe the tempo of progression, if any, to more overt signs of malignancy.

Acute Disease↗

PubMed2002

A practical, comprehensive classification for pediatric myelodysplastic syndromes: the CCC system.

PURPOSE: Pediatric myelodysplastic syndromes (MDS) are biologically diverse. The French-American-British (FAB) classification of adult forms of MDS is not always applicable because many pediatric patients do not fit into any of the categories. To circumvent the FAB schema and other flawed formats, the authors developed a practical classification system for childhood MDS. PATIENTS AND METHODS: The authors analyzed 40 children with MDS diagnosed in Toronto between 1988 and 1998 to test the utility of the classification. Children were classified according to three main features: category, cytology, and cytogenetics. RESULTS: Using this system the authors were able to classify all 40 patients; about half could not be classified by FAB. Patients could also be longitudinally classified by serial analysis to show progression of disease. Juvenile myelomonocytic leukemia was excluded because of its known myeloproliferative pathogenesis. Chronic myelomonocytic leukemia, which almost never occurs in children, was also omitted. Also excluded were other chronic myeloproliferative disorders and any cytopenias without malignant potential. CONCLUSIONS: Based on these data, the CCC system appears to have prognostic potential; children with advanced class and cytogenetic abnormalities had a poorer outcome. The authors urge international adoption of this system for uniformity in clinical practice and reporting purposes.

Adolescent↗

PubMed2002

Telomeres, X-inactivation ratios, and hematopoietic stem cell transplantation in humans: a review.

The marrow repopulating hematopoietic stem cells (HSCs) in an auto- or allograft represent a small fraction of the normal complement of HSCs, yet are required to reconstitute hematopoiesis and sustain it for the lifetime of the recipient. Such a burden imposes a "replicative stress" upon hematopoietic stem/progenitor cells. The finding of accelerated telomere shortening in hematopoietic stem cell transplant (HSCT) recipients raised the specter of accelerated hematopoietic aging. Here, we review the HSCT telomere literature and other studies of surrogate markers of HSC behavior conducted in human HSCT recipients. We present a paradigm for posttransplant hematopoietic reconstitution and speculate on the fate of HSCs in the human transplant setting.

Animals↗

PubMed2002

Malignant myeloid transformation in congenital forms of neutropenia.

BACKGROUND: Granulocyte colony-stimulating factor has had a major impact on the 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 (termed Kostmann's syndrome herein) and Shwachman-Diamond syndrome have developed myelodysplastic syndrome and acute myeloid leukemia, which raises the question of the role of G-CSF in pathogenesis. The issue is complicated because both disorders have a propensity for MDS or AML as part of their natural history. OBJECTIVE AND METHODS: To address this, the Severe Chronic Neutropenia International Registry used its large database of chronic neutropenia patients treated with G-CSF to determine the incidence of malignant myeloid transformation in the two disorders, and its relationship to treatment and to other patient characteristics. RESULTS: As of January 2001, of the 383 patients with congenital forms of neutropenia in the Registry, 48 had MDS or AML (crude rate, about 12.5%). No statistically significant relationships were found between age at onset of MDS or AML and patient gender, G-CSF dose, or duration of G-CSF therapy. What was observed, however, was the multistep acquisition of aberrant cellular genetic changes in marrow cells from Kostmann's syndrome patients who transformed, including activating ras oncogene mutations, clonal cytogenetic abnormalities, and G-CSF receptor mutations. The latter in murine models produces a hyperproliferative response to G-CSF, confers resistance to apoptosis, and enhances cell survival. CONCLUSIONS: Since Kostmann's syndrome and Shwachman-Diamond syndrome are inherited forms of bone marrow failure, G-CSF may accelerate the propensity for MDS/AML in the genetically altered stem and progenitor cells, especially in those with G-CSF receptor and ras mutations (82% and 50% of Kostmann's syndrome patients who transform, respectively). Alternatively, and equally plausible, G-CSF may simply be an innocent bystander that corrects neutropenia, prolongs patient survival, and allows time for the malignant predisposition to declare itself. Only careful long-term follow-up of the cohort of patients receiving G-CSF will provide the answer.

Cell Transformation, Neoplastic↗