Biomedical subjects
Publications and source records attributed to Jeffrey M Lipton.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The genetic basis of Diamond-Blackfan anaemia (DBA), a congenital erythroid hypoplasia that shows marked clinical heterogeneity, remains obscure. However, the fact that nearly one-quarter of patients harbour a variety of mutations in RPS19, a ribosomal protein gene, provides an opportunity to examine whether haplo-insufficiency of RPS19 protein can be demonstrated in certain cases. To that end, we identified 19 of 81 DBA index cases, both familial and sporadic, with RPS19 mutations. We found 14 distinct insertions, deletions, missense, nonsense and splice site mutations in the 19 probands, and studied mutations in 10 patients at the RNA level and in three patients at the protein level. Characterization of the mutations in 10 probands, including six with novel insertions, nonsense and splice site mutations, showed that the abnormal transcript was detectable in nine cases. The RPS19 mRNA and protein in CD34+ bone marrow cells identified haplo-insufficiency in three cases predicted to have one functional allele. Our data support the notion that, in addition to rare DBA patients with the deletion of one allele, the disease in certain other RPS19 mutant patients is because of RPS19 protein haplo-insufficiency.
New discoveries in cell biology, molecular biology and genetics have unveiled some of the pathophysiological mysteries of some of the bone marrow failure syndromes. Many of these discoveries have revealed why these syndromes show so much clinical overlap and some hold the potential for influencing the development of new therapies. In children and adults with pancytopenia and hypoplastic bone marrows proper differential diagnosis requires that some attention be directed toward defining molecular and cellular pathogenetic mechanisms because, once identified, some of these mechanisms will clearly suggest rational therapeutic approaches, treatment options that should be avoided, or both. In Section I, Drs. Jeffrey Lipton and Grover Bagby review the approach to diagnosis and management of patients with the inherited bone marrow failure syndromes, Fanconi anemia, dyskeratosis congenita, Diamond-Blackfan anemia, and the Shwachman-Diamond syndrome. Extraordinary progress has been made in identifying the genes bearing pathogenetically relevant mutations in these disorders, but slower progress has been made in defining the precise functions of the proteins these genes encode in normal cells, in part because it is increasingly obvious that the proteins are multifunctional. In practice, it is clear that in patients with dyskeratosis congenita and Fanconi anemia, the diagnosis must be considered not only in children but in adults as well. In Section II, Dr. Elaine Sloand outlines a very practical and evidence-based approach to diagnosis and management of acquired hypoplastic states emphasizing overlap between non-clonal and clonal hematopoiesis is such conditions. The pathogenesis of T lymphocyte-mediated marrow failure is presented as a clear-cut rationale for use of immunosuppressive therapy and stem cell transplantation. Practical management of patients with refractory disease with and without evidence of clonal evolution (either paroxysmal nocturnal hemoglobinuria [PNH] or myelodysplasia [MDS]) is presented. In Section III, the challenge of hypoplastic MDS is reviewed by Dr. Charles Schiffer. After reviewing the most up-to-date classification scheme, therapeutic options are reviewed, focusing largely on agents that have most recently shown some promising activity, including DNA demethylating agents, thalidomide and CC5013, arsenic trioxide, and immunosuppressive therapy. Here are also outlined the rationale and the indications for choosing allogeneic bone marrow transplantation, the only therapy with known curative potential.
Explore the source record for details and available documents.
Since 1968 HSCT utilizing bone marrow as a stem cell source has become an accepted treatment modality for a variety of immunologic, hematologic and malignant disorders. However, with widespread use it became apparent that BM donation is inconvenient, uncomfortable and not without risk. These observations led to a search for a more easily and safely acquired hematopoietic stem cell source. Recent experience suggests that peripheral blood may serve as an alternative to marrow. Indeed if the current trend continues PBSC will soon replace BM in adults as the preferred stem cell source for both HLA-matched and unrelated HSCT. Furthermore adults who have experienced both seem to prefer PBSC to BM donation. Recently a number of small trials support the feasibility of PBSC harvest from HLA-matched minor sibling donors. With regard to the recipient, data indicate more rapid engraftment, an acceptable incidence of acute and chronic GVHD, decreased infection and an increased survival for patients with malignancies (suggesting an increased GVT/L effect) when PBSC are utilized. These observations based almost entirely on the adult experience are far from definitive when children are considered. The relatively lower risk and severity of acute and chronic GVHD, the more frequent use of HSCT for non-malignant disorders and the diminished role of GVT/L in the treatment of typical malignancies are factors particular to pediatric HSCT. In addition the sense that mobilization and harvest of PBSC may pose unique and significant risk for the young donor suggest to some that PBSC may not posses sufficient advantage to warrant their use in the pediatric transplant setting. Thus both the available adult-derived data and experience suggest clinical equipoise with regard to the choice of stem cell product, under certain circumstances, when children are considered. This circumstance strongly supports the need for a comprehensive study evaluating the safety and efficacy of PBSC vs. BM HSCT in children.
Explore the source record for details and available documents.
PURPOSE: To improve efficacy and reduce toxicity of treatment for children with acute lymphoblastic leukemia. PATIENTS AND METHODS: Patients from all risk groups, including infants and those with T-cell disease, were treated between 1987 and 1991. Standard-risk (SR) patients did not receive cranial irradiation, whereas high-risk (HR) and very high-risk (VHR) patients participated in a randomized comparison of 18 Gy of cranial irradiation conventionally fractionated versus two fractions per day (hyperfractionated). RESULTS: At a median follow-up of 9.2 years, the 9-year event-free survival (EFS +/- SE) was 75% +/- 2% for all 369 patients, 77% +/- 4% for the 142 SR patients, and 73% +/- 3% for the 227 HR/VHR patients (P =.37 comparing SR and HR/VHR). The CNS, with or without concomitant bone marrow involvement, was the first site of relapse in 19 (13%) of the 142 SR patients: 16 (20%) of 79 SR boys and three (5%) of 63 SR girls. This high incidence of relapses necessitated a recall of SR boys for additional therapy. CNS relapse occurred in only two (1%) of 227 HR and VHR patients. There were no outcome differences found among randomized treatment groups. Nine-year overall survival was 84% +/- 2% for the entire population, 93% +/- 2% for SR children, and 79% +/- 3% for HR and VHR children (P <.01 comparing SR and HR/VHR). CONCLUSION: A high overall survival outcome was obtained for SR patients despite the high risk of CNS relapse for SR boys, which was presumed to be associated with eliminating cranial radiation without intensifying systemic or intrathecal chemotherapy. For HR/VHR patients, inability to salvage after relapse (nearly all of which were in the bone marrow) remains a significant clinical problem.
In this study, we aimed to estimate the contribution of environmental pollutants to the incidence, prevalence, mortality, and costs of pediatric disease in American children. We examined four categories of illness: lead poisoning, asthma, cancer, and neurobehavioral disorders. To estimate the proportion of each attributable to toxins in the environment, we used an environmentally attributable fraction (EAF) model. EAFs for lead poisoning, asthma, and cancer were developed by panels of experts through a Delphi process, whereas that for neurobehavioral disorders was based on data from the National Academy of Sciences. We define environmental pollutants as toxic chemicals of human origin in air, food, water, and communities. To develop estimates of costs, we relied on data from the U.S. Environmental Protection Agency, Centers for Disease Control and Prevention, National Center for Health Statistics, the Bureau of Labor Statistics, the Health Care Financing Agency, and the Practice Management Information Corporation. EAFs were judged to be 100% for lead poisoning, 30% for asthma (range, 10-35%), 5% for cancer (range, 2-10%), and 10% for neurobehavioral disorders (range, 5-20%). Total annual costs are estimated to be $54.9 billion (range $48.8-64.8 billion): $43.4 billion for lead poisoning, $2.0 billion for asthma, $0.3 billion for childhood cancer, and $9.2 billion for neurobehavioral disorders. This sum amounts to 2.8 percent of total U.S. health care costs. This estimate is likely low because it considers only four categories of illness, incorporates conservative assumptions, ignores costs of pain and suffering, and does not include late complications for which etiologic associations are poorly quantified. The costs of pediatric environmental disease are high, in contrast with the limited resources directed to research, tracking, and prevention.