Search PubMed⌕ Search

Biomedical subjects

L G Tone

Publications and source records attributed to L G Tone.

At least 19 recordsLinked to original sources
PubMed2006

Cytosine arabinoside-metabolizing enzyme genes are underexpressed in children with MLL gene-rearranged acute lymphoblastic leukemia.

Infant acute lymphoblastic leukemia (IALL) is characterized by mixed lineage leukemia (MLL) gene rearrangements, unique gene expression profiles, poor prognosis, and drug resistance. One exception is cytosine arabinoside (Ara-C) to which IALL cells seem to be more sensitive. We quantified mRNA expression of Ara-C key enzymes in leukemic lymphoblasts from 64 Brazilian ALL children, 15 of them presenting MLL gene rearrangement, and correlated it with clinical and biological features. The diagnosis was based on morphological criteria and immunophenotyping using monoclonal antibodies. MLL gene rearrangements were detected by conventional cytogenetic analysis, RT-PCR and/or fluorescence in situ hybridization. The DCK and HENT1 expression levels were determined by real-time quantitative PCR using SYBR Green I. Relative quantification was made by the standard curve method. The results were analyzed by Mann-Whitney and Fisher exact tests. A P value of <or=0.05 was considered to be statistically significant. DCK and HENT1 expression levels were significantly lower in children with MLL gene-rearranged ALL compared to children with MLL germ line ALL (P = 0.0003 and 0.03, respectively). Our results differ from previous ones concerning HENT1 mRNA expression that observed a higher expression level in MLL gene-rearranged leukemias. In conclusion, the expression of the genes related to Ara-C metabolism was lower in MLL-positive children in the sample studied, suggesting the presence of population differences in the expression profile of these genes especially for HENT1.

Antimetabolites, Antineoplastic↗
PubMed2004

Lack of evidence for mutations or deletions in the CDKN2A/p16 and CDKN2B/p15 genes of Brazilian neuroblastoma patients.

Neuroblastoma, the most common extracranial tumor in childhood, has a wide spectrum of clinical and biological features. The loss of heterozygosity within the 9p21 region has been reported as a prognostic factor. Two tumor suppressor genes located in this region, the CDKN2B/p15 and CDKN2A/p16 (cyclin-dependent kinase inhibitors 2B and 2A, respectively) genes, play a critical role in cell cycle progression and are considered to be targets for tumor inactivation. We analyzed CDKN2B/p15 and CDKN2A/p16 gene alterations in 11 patients, who ranged in age from 4 months to 13 years (male/female ratio was 1.2:1). The most frequent stage of the tumor was stage IV (50%), followed by stages II and III (20%) and stage I (10%). The samples were submitted to the multiplex PCR technique for homozygous deletion analysis and to single-strand conformation polymorphism and nucleotide sequencing for mutation analysis. All exons of both genes were analyzed, but no deletion was detected. One sample exhibited shift mobility specific for exon 2 in the CDKN2B/p15 gene, not confirmed by DNA sequencing. Homozygous deletions and mutations are not involved in the inactivation mechanism of the CDKN2B/p15 and CDKN2A/p16 genes in neuroblastoma; however, these two abnormalities do not exclude other inactivation pathways. Recent evidence has shown that the expression of these genes is altered in this disease. Therefore, other mechanisms of inactivation, such as methylation of promoter region and unproperly function of proteins, may be considered in order to estimate the real contribution of these genes to neuroblastoma genesis or disease progression.

Adolescent↗
PubMed2004

Analysis of ETV6/RUNX1 fusions for evaluating the late effects of cancer therapy in ALL (acute lymphoblastic leukemia) cured patients.

Acute Lymphoblastic Leukemia (ALL) is the most common malignancy in childhood. The improvements of therapies have increased the number of long-term survivors. However, an increased incidence of secondary neoplasias has been observed in this cohort. Our purpose was to evaluate the late effects of cancer therapy in cured patients previously treated for ALL, considering previous reports on the occurrence of gene fusions as putative markers of chromosomal instability. Twelve ALL patients (aged 5 to 16 years) and twelve healthy subjects (aged 18 to 22 years) were studied for the presence of ETV6/RUNX1 (TEL/AML1) translocations, which were detected by FISH (fluorescence in situ hybridization). The blood samples were collected months or years after completion of the therapy, and the frequencies of gene fusions in lymphocytes were compared with those obtained retrospectively for bone marrow samples at the time of diagnosis, and also for the control group. It was demonstrated that ETV6/RUNX1 gene fusion was a frequent event (0.59-1.84/100 cells) in peripheral blood lymphocytes from normal individuals and the ALL patients who underwent chemotherapy showed significantly (P = 0.0043) increased frequencies (0.62-3.96/100 cells) of the rearrangement when compared with the control groups (patients at diagnosis and healthy subjects). However, a significant difference was not found between the groups of patients at diagnosis and healthy subjects, when the two patients who were positive for the rearrangement were excluded. Therefore, increased frequencies of ETV6/RUNX1 fusions in ALL cured patients indicate the influence of previous exposure to anti-cancer drugs, and they may represent an important genetic marker for estimating the risk of relapse, or development of secondary neoplasias.

Adolescent↗
PubMed2001

Prognostic significance of bi/oligoclonality in childhood acute lymphoblastic leukemia as determined by polymerase chain reaction.

CONTEXT: The CDR-3 region of heavy-chain immunoglobulin has been used as a clonal marker in the study of minimal residual disease in children with acute lymphoblastic leukemia. Southern blot and polymerase chain reaction studies have demonstrated the occurrence of bi/oligoclonality in a variable number of cases of B-lineage acute lymphoblastic leukemia, a fact that may strongly interfere with the detection of minimal residual disease. Oligoclonality has also been associated with a poorer prognosis and a higher chance of relapse. OBJECTIVES: To correlate bi/oligoclonality, detected by polymerase chain reaction in Brazilian children with B-lineage acute lymphoblastic leukemia with a chance of relapse, with immunophenotype, risk group, and disease-free survival. DESIGN: Prospective study of patients outcome. SETTING: Pediatric Oncology Unit of the University Hospital, Faculty of Medicine of Ribeirão Preto, University of São Paulo. PARTICIPANTS: 47 children with acute lymphoblastic leukemia DIAGNOSTIC TEST: Polymerase chain reaction using consensus primers for the CDR-3 region of heavy chain immunoglobulin (FR3A, LJH and VLJH) for the detection of clonality. RESULTS: Bi/oligoclonality was detected in 15 patients (31.9%). There was no significant difference between the groups with monoclonality and biclonality in terms of the occurrence of a relapse (28.1% versus 26.1%), presence of CALLA+ (81.2% versus 80%) or risk group (62.5% versus 60%). Disease-free survival was similar in both groups, with no significant difference (p: 0.7695). CONCLUSIONS: We conclude that bi/oligoclonality was not associated with the factors investigated in the present study and that its detection in 31.9% of the patients may be important for the study and monitoring of minimal residual disease.

Adolescent↗
PubMed2001

The methylenetetrahydrofolate reductase C677T gene polymorphism decreases the risk of childhood acute lymphocytic leukaemia.

We have determined the prevalence of methylenetetrahydrofolate reductase (MTHFR) mutations C677T and A1298C in 71 children (< or = 15 years) with acute lymphoblastic leukaemia (ALL) and in 71 control subjects. Odds ratio (OR) for ALL linked to MTHFR C677T was 0.4 (95% CI 0.2-0.8); for heterozygotes it was 0.5 (95% CI 0.2-0.9) and for homozygotes it was 0.3 (95%CI 0.09-0.8). MTHFR A1298C yielded an overall OR for ALL of 1.3 (95% CI: 0.7-2.6); for heterozygotes it was 1.3 (95% CI: 0.7-7.6) and for homozygotes it was 2.8 (95% CI 0.5-15.6). In conclusion, MTHFR C677T was linked to a significant 2.4-fold decreased risk of developing childhood ALL, whereas MTHFR A1298C did not significantly affect the risk of ALL in our population.

Adolescent↗
PubMed2000

Analysis of the p53 gene by PCR-SSCP in ten cases of Wilms' tumor.

CONTEXT: Mutations of the p53 tumor suppressor gene are the most frequent alterations observed in human neoplasias affecting adults. In pediatric oncology, however, they have seldom been identified. Wilms' tumor is a renal neoplasia commonly occurring in children and is associated with mutations of the WT1 gene. The correlation between Wilms' tumor and alterations of the p53 gene has not been well established, with a low frequency of mutations having been reported in this type of tumor. Mutation may be associated with advanced stage disease and unfavorable histology. OBJECTIVE: To screen for mutations of the p53 gene by the PCR-SSCP method and DNA sequencing in cases of Wilms' tumor sug-gestive of mutation. DESIGN: Case Report. CASE REPORT: Evaluations of exons 5-9 of the p53 gene in DNA samples extracted by PCR-SSCP from 10 Wilms' tumors in children at different stages, and DNA sequencing. Changes in SSCP analy-sis were observed in exon 8 in two samples. The probable muta-tions were not confirmed by DNA sequencing. The absence of point mutations in p53 gene observed in the 10 samples of Wilms' tumor studied agrees with literature data, with DNA sequencing being of fundamental importance for the confirmation of possible mutations.

Child↗
PubMed1999

Nutritional assessment and serum zinc and copper concentration in leukemic children.

CONTEXT: Malnutrition in childhood cancer is commonly a serious problem. Changes in blood zinc and copper have also been found in malignant diseases. OBJECTIVE: To describe the protein-energy nutritional status and serum zinc and copper of children with newly diagnosed leukemia. DESIGN: Cross-sectional study. SETTING: University referral center. PARTICIPANTS: 23 children with newly diagnosed acute lymphocytic leukemia (ALL) or acute non-lymphocytic leukemia (ANLL) between the ages of 1 and 10 years. The control subjects were 31 healthy school children of similar age from local schools. MAIN MEASURES: Anthropometric measurements of height/age and weight/height, food intake and serum levels of zinc and copper. RESULTS: Almost the entire group of children were eutrophic. Zinc and copper intake were below the recommended values. Serum zinc levels were significantly lower and serum copper levels were significantly higher in the leukemic group when compared to normal children. CONCLUSION: At the time of diagnosis the children suffering from leukemia were not overtly malnourished but blood analysis showed alterations in concentrations of the trace elements zinc and copper.

Age Distribution↗
PubMed1999

CD10 and CD19 fluorescence intensity of B-cell precursors in normal and leukemic bone marrow. Clinical characterization of CD10(+strong) and CD10(+weak) common acute lymphoblastic leukemia.

In order to assess the age-related changes in CD10 and CD19 fluorescence intensity (FI) the present study analyzed by flow cytometry 56 sternal biopsies from 'normal' infants, children and adults undergoing cardiac surgery. The CD10(+weak) subset was predominant in all age groups, representing approximately 50% of the bone marrow (BM) lymphoid cells in children younger than 4 years. Both CD10+ subsets significantly decreased with age but their ratio did not differ significantly. Moreover, the intensity of CD10 and CD19 fluorescence in the strong and weak subsets did not vary with age. The CD19 intensity was significantly higher in CD10(+weak) than in CD10(+strong) cells. In addition, we classified as CD10(+weak) or CD10(+strong) the leukemic cells from BM aspirates of 117 patients with common acute lymphoblastic leukemia (cALL) (78 children and 39 adults). A higher frequency of cases expressing the CD19+ CD10(+strong) phenotype was observed both in children and adults. Children of the CD10(+weak) group tended to be older than those of the CD10(+strong) group (median = 7 vs. 4 years, P = 0.07), and presented a significantly higher frequency of splenomegaly (93.7 vs. 55%, P = 0.04), which was massive in about 60% of these cases. Among adults, a significantly higher frequency of cases expressing the CD10(+weak) phenotype was observed in females. No other clinical or biological difference was detected between the two groups either for children or adults. Concerning the treatment outcome, we did not observe significant differences in complete remission rate (CRR) or in disease free survival (DFS) among the 32 children and 28 adults analyzed. Finally, we compared the CD10 and CD19 intensity in normal and leukemic BM. Overexpression of either or both antigens in leukemic cells was observed in 42.4% of the cALL cases. In these cases, using cut off values of 110 afu for the CD10 FI and of 100 afu for the CD19 FI, the detection of leukemic cells was possible at levels of 0.2% based on CD10 analysis, of 0.6% based on CD19, and 0.02% when both antigens were overexpressed. In conclusion, we demonstrated that the heterogeneity of CD10 and CD19 fluorescence intensity is of no clinical relevance in cALL, although its study may be helpful for the diagnosis and the detection of minimal residual disease.

Adolescent↗
PubMed1996

Translocation (1;5)(q32;q35) in CD30+ anaplastic large cell non-Hodgkin lymphona of childhood. A case report.

The authors studied cytogenetically a case of CD30+ anaplastic large cell non-Hodgkin lymphoma previously diagnosed as malignant histiocytosis and detected a translocation involving chromosomes 1 and 5, t(1;5)(q32:q35). After comparing their findings with those from reports in the literature, they comment about the importance of breakpoint q35 on chromosome 5 and point out the importance of associating morphologic, immunoperoxidase, and cytogenetic findings to confirm the diagnosis of this tumor.

Chromosome Fragility↗
PubMed1995

Splenic function in acute leukemia.

Spleen function was evaluated in 36 patients with acute leukemia by enumeration of pitted erythrocytes and analysis of clearance from circulation of heat-damaged 99mTc-labelled erythrocytes (HDE). At diagnosis, the mean percentage of pitted erythrocytes was significantly higher in the patient group (4.04 +/- 7.19%) than in the control group (0.41 +/- 0.35%; p < 0.01), suggesting the occurrence of a splenic hypofunction in a high proportion of the patients. Accordingly, the clearance of HDE showed a pattern of splenic hypofunction in 4 out of 7 patients, based on reduced values for the parameters C20 (overall clearing function of the spleen), K (the rate constant of HDE irreversibly trapped) and K/K1 + K (the fraction of HDE entering the spleen undergoing permanent removal). After successful treatment, the pit counts decreased in all reassessed patients, returning to normal values in 10 out of 12 patients with high pit counts at diagnosis. Additionally, two patients with normal pit counts at diagnosis presented borderline results for the parameters C20 and K, which may suggest a slight splenic hyperactivity in these patients. These results demonstrate, for the first time, the presence of functional spleen abnormalities in patients with acute leukemia.

Acute Disease↗
PubMed1992

Growth and sexual maturation of Brazilian patients with sickle cell diseases.

Growth and sexual maturation was studied of 125 Brazilian patients with sickle cell disease whose ages ranged from 7 months to 42 years. Height and weight were significantly lower when compared with the unaffected population. The height and weight deficit increased in the age range of 11-19 years as compared with patients less than 11 years of age. Age of menarche, breast and pubic hair staging in girls, and genitalia staging and testicular volume measurements in boys indicated a delayed sexual maturation for both sexes. The comparison of adult and young patients, however, demonstrated that although puberty is delayed, a normal sexual maturation is attained later in life by most patients.

Adolescent↗
PubMed1990

Cytogenetic study of a case of childhood erythroleukemia.

We report a case of childhood erythroleukemia diagnosed by French-American-British Cooperative group (FAB) and by cytogenetic analysis of bone marrow cells. The following major chromosome anomalies were detected: hyperdiploidy with a modal number of 49, three markers consisting of translocations between chromosomes 3, 9, 20, and 15, deletion of the long arm of chromosome 16 (q22----qter), and karyotype instability. These changes were compared with others reported in the literature and discussed in terms of their importance for diagnostic confirmation.

Bone Marrow↗
PubMed1989

Liposarcoma of hepatic hilum in childhood: report of a case and review of the literature.

Liposarcoma in childhood has seldom been documented. The rare occurrence of this tumor has resulted in a lack of information about its natural history, prognosis, and management. The differential diagnosis with lipoblastomatosis is obligatory. A 2 year 4 month-old white male child presented at the Hospital das Clinicas of Medical School of Ribeirão Preto, University of São Paulo, with fever, jaundice, and coluria secondary to a tumoral mass of the hepatic hilum causing obstruction of the biliary tree. Histologic and immunohistochemical study at autopsy disclosed a liposarcoma. A literature review found 64 other reported cases. Special attention was given to age, sex, anatomic localization, and histologic aspects of the literature cases. Liposarcoma involving the hepatic hilum and causing obstruction of the biliary tree in childhood was not previously reported in the literature.

Bile Ducts, Intrahepatic↗
PubMed1984

Treatment of sickle cell diseases with aspirin.

The effects of long-term aspirin for the treatment of sickle cell disease were compared with placebo in a double-blind trial completed by 29 patients. Each patient was submitted to a 5-month period of treatment with aspirin (median dose 31 mg/kg/day) and an equivalent period with placebo. No clinical or laboratory differences were observed between the two phases, including the frequency of painful crises and infectious episodes, hemoglobin concentration, PCV, reticulocytes, Hb F, bilirubin, irreversibly sickled cells, filterability of red cell, sickling in vitro and hypoxia-induced potassium loss.

Adolescent↗
PubMed1983

Hereditary hemoglobin disorders in a Brazilian population.

A survey of hereditary hemoglobin disorders in a mixed Brazilian population of the northeast of the State of S. Paulo revealed a 5.3% incidence of abnormal phenotypes among 400 schoolchildren, 4.5% among 602 mothers and 2.8% among 606 newborns. The most common findings were AS (1.9%), AC (0.8%) and beta-thalassemia (0.8%) heterozygotes, which amount to 3.5% of the sample. In a second selected population of 1,023 patients of the Hematologic Clinic of the University Hospital and their relatives, 471 cases of hemoglobinopathies were detected. The most frequent anomalies were heterozygous beta-thalassemia (35.2%) and Hb S (32.5%), followed by sickle-cell anemia (13.0%), homozygous beta-thalassemia (4.0%) and sickle-cell/beta-thalassemia (4.0%). Other defects detected were delta-beta-thalassemia, Hb C, Hb Hasharon and Hb A2'. One family with alpha-thalassemia has been identified that included a girl with Hb H disease. The significance of these findings is discussed with regard to the racial origin of the population of this region.

Brazil↗
PubMedDate not supplied

Childhood B lineage acute lymphoblastic leukemia clonality study by the polymerase chain reaction.

PURPOSE: B cell precursors acute lymphoblastic leukemia (ALL) present rearrangements in the heavy chain immunoglobulin and T cell receptor genes, especially in the complementarity determining region 3 (CDR-3) and T cell receptor delta (TCR delta) (V delta 2 D delta 3) regions. These rearrangements may be amplified by the polymerase chain reaction (PCR) and used as clonal markers of B lineage ALL. Our purpose was to study clonality at the DNA level by PCR in B lineage ALL. PATIENTS AND METHODS: Fifty-three pediatric patients (36 with B lineage ALL, 7 with ALL-T, and 10 with nonlymphocytic disease) were investigated using consensus primers for the CDR-3 regions of IgH and TCR delta. RESULTS: Clonality was detected in 86.1% of the patients with B lineage ALL when the primers for the CDR-3 regions were used, in 41.6% when the primers for TCR delta were used, and in 91.6% when the two primers were used together. Biclonality was found in 22.5% and 6.6% of patients that have shown clonality for CDR-3 and TCR delta, respectively. Clonality was not detected in any other samples using these primers. CONCLUSIONS: PCR using CDR-3 and TCR delta primers can be used as an aid for B lineage ALL diagnosis and clonal evolution of theses disease.

Burkitt Lymphoma↗
PubMedDate not supplied

[Treatment of lymphangioma with alpha-2a-interferon]

OBJECTIVE: To describe the results of the use of alpha-2a-interferon in the treatment of inoperable childhood lymphangiomas refractory to other therapeutic management. METHOD: We reviewed the literature about pathogenic events and the treatments available for lymphangiomas. Based on that, we used alpha-2a-interferon at a dose of 3 million units/m(2)/day administered subcutaneously to patients with inoperable disease and no response to other treatments. We conducted periodic clinical and laboratory control to evaluate the response and the adverse reactions to alpha-2a-interferon administration. RESULTS: We observed that the 6 patients with inoperable lymphangiomas who used alpha-2a-interferon had a satisfactory clinical response associated with minimum adverse reactions. Of these patients, 5 had partial regression of their lesions, and 1 remained stable. CONCLUSION: Alpha-2a-interferon may be one more available treatment for inoperable childhood lymphangiomas.

Journal Article↗