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Biomedical subjects

Raul Ribeiro

Publications and source records attributed to Raul Ribeiro.

12 recordsLinked to original sources
PubMed2006

Outcome of hematopoietic stem cell transplantation for pediatric patients with therapy-related acute myeloid leukemia or myelodysplastic syndrome.

BACKGROUND: Therapy-related myelodysplastic syndrome (t-MDS) and acute myeloid leukemia (t-AML) carry a poor prognosis. We analyzed the results of allogeneic HSCT in 38 children to determine which factors, if any, affected outcome. PROCEDURE: The effects of demographic, donor, and disease-related factors were analyzed to determine their effects on overall and disease-free survival (OS, DFS), relapse, and non-relapse mortality (NRM). RESULTS: OS and DFS for t-AML and t-MDS were similar. Three-year OS and EFS were the same (15.4 +/- 5.8%) and the 3-year NRM was 59.6 +/- 8.4%. The 1-year cumulative risk of grade III-IV acute graft-versus-host disease (GVHD) and relapse were 23.7 +/- 7.0% and 18.7 +/- 6.5%, respectively. The percentage of pre-transplant bone marrow (BM) blasts was positively associated with relapse (P = 0.05), while the percentage of BM blasts at diagnosis of therapy-related disease tended to associate with NRM (P = 0.07). Alternative donor and matched sibling donor grafts had similar outcomes. NRM was higher among patients who did not develop acute GVHD as compared to those with grade 1-2 acute GVHD (69.2 +/- 14.2% vs. +/- 12.7%, respectively), while NRM was 100% in patients with grade III-IV acute GVHD (P = 0.007). CONCLUSIONS: The percentage of BM blasts is associated with relapse in these disorders. High rates of NRM negatively impact the outcome of allogeneic HSCT for children with t-AML and t-MDS. Future studies should focus on reducing NRM.

Adolescent↗
PubMed2005

Pharmacogenetics of outcome in children with acute lymphoblastic leukemia.

Acquired genetic characteristics of acute lymphoblastic leukemia (ALL) cells are used to individualize therapy, whereas germ line genetic characteristics generally are not. We determined whether ALL outcome was related to 16 genetic polymorphisms affecting the pharmacodynamics of antileukemic agents. Of 246 children, 116 were treated on the lower-risk (LR) and 130 on the higher-risk (HR) arms of a St Jude protocol. Patients in the HR group with the glutathione S-transferase (GSTM1) non-null genotype had greater risk of hematologic relapse (P = .03), which was further increased by the thymidylate synthetase (TYMS) 3/3 genotype (P = .03). These genotypes remained predictive in multivariate analyses (P < .001 and .003, respectively). No genotypes were predictive in the LR arm. Expression of these 2 genes in ALL blasts was lower in those with low-activity genotypes. For central nervous system relapse, among the HR group, the vitamin D receptor start site (P = .02) and intron 8 genotypes (P = .04) predisposed, whereas for LR patients the TYMS 3/3 genotype predisposed (P = .04). The GSTM1 non-null and TYMS 3/3 genotypes are plausibly linked to drug resistance. Polymorphisms interact to influence antileukemic outcome and represent determinants of response that can be used to optimize therapy.

Alleles↗
PubMed2005

New rearrangement t(3;17)(q26.3;q12) in an AML patient with a poor outcome.

In more than 90% of acute promyelocytic leukemia (APL) cases a reciprocal translocation t(15;17)(q22;q12) can be observed. The RARalpha gene on 17q12 is known to have other translocation partners than PML (in 15q22) in a minority of APL cases. Here, we describe a previously unrecorded chromosomal translocation involving the RARalpha gene and an unknown partner on chromosome 3. The chromosomal rearrangement was studied in detail by 24-color-FISH using whole chromosome painting probes plus multicolor banding. Thus, the breakpoint could be characterized as t(3;17) (q26;q12). In this case 10% of blasts showed AML-M3 characteristics although typical rearrangements with RARalpha were not detected by molecular methods. The characterization of the present and other comparable APL-cases with exceptional translocation partners of PML or RARalpha will help to enlighten the understanding of the pathogenesis of APL.

Adult↗
PubMed2005

Pond4Kids - an multi-site online Pediatric Oncology Research Database for collaborative protocol research.

Abstract: The Pediatric Oncology Networked Database (POND4Kids) is an online, multilingual database for pediatric hematology/oncology patients. Its purpose is to improve the care of pediatric oncology patients in countries with limited resources by the exchange of information and experience between oncologists in diverse geographic regions who practice in a similar medical environment.

Child↗
PubMed2004

Pharmacogenetic risk factors for osteonecrosis of the hip among children with leukemia.

PURPOSE: One of the adverse effects of therapy for acute lymphoblastic leukemia (ALL) is osteonecrosis of the hip. Putative risk factors for osteonecrosis have included being female, white race, and older age. Our goal was to define possible genetic risk factors for osteonecrosis among children treated for newly diagnosed ALL. METHODS: Using a candidate gene approach, we determined the genotypes for 16 common polymorphisms in genes likely to affect the pharmacokinetics or pharmacodynamics of antileukemic medications in 64 children with ALL. Therapy included glucocorticoids and antifolates. Magnetic resonance imaging of both hips was used to diagnose osteonecrosis, and was performed at similar times from the start of ALL therapy (P =.61) in the 25 patients with and the 39 patients without osteonecrosis (median, 447 days and 443 days, respectively). RESULTS: In addition to age older than 10 years (odds ratio [OR], 24.2; P =.0001) and white race (OR, 11.1; P =.037), host factors for osteonecrosis included the vitamin D receptor FokI start site CC genotype (OR, 4.5; P =.045), and the thymidylate synthase low activity 2/2 enhancer repeat genotype (OR, 7.4; P =.049). CONCLUSION: Because folate-related and vitamin D-receptor genetic variants have been associated with bone and vasculature morbidity, these pharmacogenetic associations likely reflect the interaction of antileukemic medications with germline sensitivity to drug actions, and might identify ALL patients at highest risk to develop osteonecrosis.

Age Factors↗
PubMed2003

Cure4Kids - building online learning and collaboration networks.

The International Outreach Program of St. Jude Childrens' Research Hospital has been developing programs to help countries with limited resources develop treatment centers to treat children with catastrophic diseases such as pediatric cancer and AIDS. Cure4Kids (www.cure4kids.org) is the Internet learning network that delivers medical education to doctors and nurses on pediatric cancer and AIDS. The objective of Cure4Kids is not only education, but also to provide tools for communications and collaborations among individuals.

Acquired Immunodeficiency Syndrome↗
PubMed2002

A mathematical model of in vivo methotrexate accumulation in acute lymphoblastic leukemia.

Methotrexate (MTX) is one of the most widely used drugs for the treatment of childhood acute lymphoblastic leukemia (ALL). Interindividual differences in lymphoblast accumulation of MTX and its active metabolites, methotrexate polyglutamates (MTXPG), may contribute to the effectiveness of treatment among ALL subtypes. To better understand these differences in MTXPG accumulation, we developed a model to characterize the cellular influx and efflux of MTX, formation of MTXPG by the addition of glutamyl residues catalyzed by FPGS (folylpolyglutamate synthetase), and cleavage of glutamyl residues from MTXPG by GGH (gamma-glutamyl hydrolase). The model was fitted to in vivo intracellular MTXPG concentrations measured serially in leukemic blasts from 20 newly diagnosed patients with ALL treated with 24-h intravenous infusions of MTX. The observed median concentrations of total MTXPG at 44 h was higher in B-lineage than in T-cell ALL (1706 vs 518 pmol/10(9) cells, P<0.025), consistent with the higher estimated Vmax for FPGS activity in B-lineage vs T-lineage blasts (414 vs 93 pmol/10(9) cells/h, P<0.008). Simulations based on the model-estimated parameters indicated greater accumulation of MTX, MTXPGs (MTXPG(2-7)) and total MTX (MTXPG(1-7)) with longer MTX infusions and with higher MTX doses, with the highest concentrations in hyperdiploid B-lineage, intermediate in non-hyperdiploid B-lineage, and lowest in T-cell ALL. These differences provide mechanistic and treatment insights for lineage and ploidy differences in MTXPG accumulation in human leukemia cells in vivo.

Aneuploidy↗
PubMed2002

Persistence of lymphoblasts in bone marrow on day 15 and days 22 to 25 of remission induction predicts a dismal treatment outcome in children with acute lymphoblastic leukemia.

We determined the prognostic importance of morphologically identifiable persistent disease at day 15 and days 22 to 25 of remission induction in childhood acute lymphoblastic leukemia (ALL). Among 546 patients entered on 2 consecutive protocols, 397 patients had evaluable bone marrow (BM) examinations on day 15 (+/- 1 day) and 218 on days 22 to 25 (+/- 1 day). Fifty-seven patients (14%) had persistent lymphoblasts (> or = 1%) in the BM on day 15 and 27 patients (5.5%) had persistent lymphoblasts on days 22 to 25. The 5-year event-free survival (EFS) was significantly worse for patients with lymphoblasts on day 15 (40% +/- 6%) or on days 22 to 25 (4% +/- 3%) as compared to those without lymphoblasts on these dates (78% +/- 2% and 76% +/- 2%, respectively, P <.001 for both comparisons). A worse prognosis was observed even for patients with a low percentage of lymphoblasts (ie, 1%-4%) at either day 15 (5-year EFS = 56% +/- 8%) or days 22 to 25 (5-year EFS = 0%) compared to those without morphologically identifiable persistent lymphoblasts at these times (P <.001 for both comparisons). The prognostic impact of persistent lymphoblasts on both dates remained significant after adjusting for other known risk factors, including treatment protocol, age, white blood cell count, DNA index, cell lineage, and central nervous system status, and National Cancer Institute/Rome criteria simultaneously. Hence, persistence of lymphoblasts (even 1%-4%) on day 15 of remission induction was associated with a poor prognosis and on days 22 to 25 signified a particularly dismal outcome; these very high-risk patients require novel or more intensive therapy to improve outcome.

Blast Crisis↗
PubMedDate not supplied

International hematology-oncology nursing education in Latin America.

In countries with limited resources, the multidisciplinary hematology-oncology (H-O) treatment team model, which relies heavily on highly trained nurses, is generally not in use. Since 1996, St. Jude Children's Research Hospital has been working with medical centers in Mexico and Central and South America to improve the specialty training of nurses in pediatric H-O. In 1999, St. Jude developed a strategic plan to organize a cooperative nursing education project. The initial preparation consisted of three phases. In phase one, a curriculum was developed. A consultant was hired to create and institute an evaluation system for nurse graduates of the program and for the program itself. Phase two explored the possible collaborations among existing training centers and contracted with a nurse educator to provide on-site support. In phase three, a core team of skilled multicultural nursing educators was formed. To initiate the program, we used the "Teach the Teachers" method. Four classes to date have trained 76 nurses from different countries in Latin America. Development of the International Training Center for Hematology-Oncology Nurses in Latin America has been a challenging and rewarding experience. We hope that others will find it useful in planning international education programs that will not only serve the nursing profession, but also improve the quality of care of all children, regardless of their background, race, religion, or economic status.

Educational Measurement↗