318 research outputs found
Analysis of the p16INK4 and TP53 Tumor Suppressor Genes in Bone Sarcoma Pediatric Patients
Recent data suggest that deletion of p16INK4 and mutation of TP53 are among the
most common genetic events in the development of human cancer, since the codified
proteins act as brakes of the abnormal cell cycle. As the molecular events
leading to the development of pediatric bone sarcomas remain unclear, we analyzed
75 osteosarcoma and Ewing sarcoma samples from 43 pediatric patients to search
for alterations at the TP53 or p16INK4 tumor suppressor genes. By means of
PCR-DGGE (polymerase chain reaction and denaturing gradient gel electrophoresis)
we detected TP53 point mutations in 18.6% of the tumor samples, but no
constitutional mutations. In the analysis of p16INK4, 7% of the samples harbored
deletions of the gene but no point mutations were detected by SSCP (single strand
conformation polymorphism) analysis, just the polymorphism Ala-->Thr at codon
148. These data support the hypothesis that TP53 alterations may play a role in
the development of pediatric bone tumors and that the primary mechanism of
inactivation of p16INK4 seems to be homozygous deletion rather than point
mutation
El ensayo de micronúcleos como medida de inestabilidad genética inducida por agentes genotóxicos
Human genetic integrity is compromised by the intense industrial activity, which emphasizes the importance to determine an "acceptable" genetic damage level and to carry out routine genotoxicity assays in the populations at risk. Micronuclei are cytoplasmatic bodies of nuclear origin which correspond to genetic material that is not correctly incorporated in the daughter cells in the cellular division; they reflect the existence of chromosomal aberrations and are originated by chromosomal breaks, replication errors followed by cellular division of the DNA and/or exposure to genotoxic agents. There are several factors able to modify the number of micronuclei present in a given cell, among them are age, gender, vitamins, medical treatments, daily exposure to genotoxic agents, etc. The cytogenetic assay for the detection of micronuclei (CBMN: cytokinesis-block micronucleus) is based on the use of a chemical agent, cytochalasin-B, which is able to block cytocinesis but allowing the nuclear division, therefore yielding binucleated and monodivided cells. The micronuclei scoring is performed on 1000 binucleated cells and the starting sample may vary, although most studies are performed on peripheral blood lymphocytes. The micronuclei assay is considered a practical, universally validated and technically feasible protocol which is useful to evaluate the genetic instability induced by genotoxic agent
Screening of the human tumor necrosis factor-alpha (TNF-α) gene promoter polymorphisms by PCR–DGGE analysis
We have designed a new PCR-DGGE technique that enables detection of base changes in the TNF-alpha gene promoter. Screening of 130 samples from Spanish children has shown that this technique accurately detects the altered band patterns induced by the presence of the polymorphisms at positions -376, -308, -238 and -163 of the promoter sequence. Although further analysis are needed to fully characterise the alterations detected, we believe that this PCR-DGGE technique is a rapid and sensitive first approach to the genetic characterisation of the TNF-alpha promote
Bone Mineral Density and Bone Metabolism In Children Treated for Bone Sarcomas
In adolescent bone sarcoma patients, bone mass acquisition is potentially compromised at a time in which it should be at a maximum. To evaluate the problem we measured bone mineral density (BMD) and serum markers of bone formation and resorption in a series of pediatric patients with bone tumors. BMD was measured by dual-energy x-ray absorptiometry, at clinical remission, for lumbar spine and the neck of the femur in 38 osteosarcoma and 25 Ewing's sarcoma patients. Mean age was 20.65 and 19.13 y respectively. Serum markers of bone metabolism were: OC, PICP, ICTP, 25-OH vit D and 1,25-(OH)(2) vit D, IGF-I, IGFBP-3 and intact PTH. Serum was sampled throughout anti-tumoral treatments and follow-up. We analyzed 85 samples from 59 osteosarcoma patients and 54 samples from 36 Ewing's sarcoma patients. Patients had decreased lumbar and femoral BMD. The decrease was more pronounced in pubertal patients compared with those who had completed pubertal development at the time of disease diagnosis. Multivariate analysis indicated that sex, age, weight and BMI were significant in lumbar BMD depletion. Weight and BMI were significant in femoral BMD depletion. Serum markers of bone formation (PICP and OC) and resorption (ICTP) were, throughout, lower than reference values. Significant alterations in other markers were also observed. Up to a third of osteosarcoma and Ewing's sarcoma patients in clinical remission had some degree of BMD deficit. The corresponding increased risk of pathologic bone fractures constitutes a reduction in future quality o
Determinación y validación de dianas implicadas en la carcinogénesis del osteosarcoma infantil mediante plataformas de genómica y Proteómica
Methotrexate in Pediatric Osteosarcoma: Response and Toxicity in Relation to Genetic Polymorphisms and Dihydrofolate Reductase and Reduced Folate Carrier 1 Expression
To determine the influence of the genotype and the level of expression of different enzymes involved in folate metabolism on the response to and toxicity of high-dose methotrexate treatment in pediatric osteosarcomas.
STUDY DESIGN: DHFR and Reduced folate carrier 1 (RFC1) semiquantitative expression was analyzed in 34 primary and metastatic osteosarcoma tissues by real-time polymerase chain reaction. The following polymorphisms were also analyzed in peripheral blood from 96 children with osteosarcoma and 110 control subjects: C677T, A1298C (MTHFR), G80A (RFC1), A2756G (MTR), C1420T (SHMT), the 28bp-repeat polymorphism, and 1494del6 of the TYMS gene. Treatment toxicity was scored after each cycle according to criteria from the World Health Organization.
RESULTS: DHFR and RFC1 expression was lower in initial osteosarcoma biopsy specimens than in metastases (P = .024 and P = .041, respectively). RFC1 expression was moderately decreased in samples with poor histologic response to preoperative treatment (P = .053). Patients with osteosarcoma with G3/G4 hematologic toxicity were more frequently TT than CT/CC for C677T/MTHFR (P = .023) and GG for A2756G/MTR (P = .048 and P = .057 for gastrointestinal and hematologic toxicity, respectively).
CONCLUSIONS: The role of C677T/MTHFR and A2756G/MTR on chemotherapy-induced toxicity should be further investigated in pediatric osteosarcomas receiving high-dose methotrexate. Altered expression of DHFR and RFC1 is a feasible mechanism by which osteosarcoma cells become resistant to methotrexate
Clinical and Molecular Features of Ewing Sarcoma in a Patient with Triple-X Syndrome
A case of Ewing sarcoma in a 16-year-old girl with 47 XXXc karyotype is reporte
Analysis of Polymorphisms of the Vitamin D Receptor, Estrogen Receptor, and Collagen Iα1 Genes and Their Relationship With Height in Children With Bone Cancer
The authors' objectives were to compare height at diagnosis of children
with bone tumors with that of Spanish reference children; to analyze the
frequency of the genotypes for the polymorphisms of the vitamin D receptor (VDR),
estrogen receptor (ER), and collagen Ialpha1 (COLIalpha1) genes in patients and
in healthy controls; and to test the relationship between the genetic markers and
height. PATIENTS AND METHODS: Height and weight at diagnosis were measured in 58
osteosarcoma and 36 Ewing sarcoma patients and compared with standards published
for Spanish reference children according to sex and age. For the molecular
analysis, genetic polymorphisms of the VDR (Fok I, Apa I, and TaqI), ER (Pvu II
and XbaI), and COLIalpha1 (Msc I) genes were characterized in 72 osteosarcoma and
53 Ewing sarcomas and in a group of 143 healthy matched children. RESULTS:
Osteosarcoma and Ewing sarcoma patients were significantly taller than Spanish
reference children. Osteosarcoma patients showed a significantly higher frequency
of the Ff genotype for the Fok I polymorphism (VDR gene) than the control group.
The odds ratio for this genotype was 1.78, with an increased relative risk of 78%
for heterozygous Ff carriers. Among Ewing sarcoma patients, this same genotype
was significantly associated with lower height than homozygotes (FF or ff).
CONCLUSIONS: Children with bone cancer are significantly taller than the
reference population, which may be influenced by the genotype for the Fok I
polymorphism of the VDR gene
Ewing Family Tumors: Potential Prognostic Value of Reverse-Transcriptase Polymerase Chain Reaction Detection of Minimal Residual Disease in Peripheral Blood Samples
In more than 95% of patients, the Ewing family of tumors (ET) has chimeric
transcripts caused by fusion of the EWS gene to either FLI1 or ERG. The presence
of specific EWS-FLI1 or EWS-ERG transcripts in peripheral blood (PB) samples of
patients being treated for ET was prospectively evaluated, and these data were
correlated to their clinical status. The authors studied 113 PB samples from 28
patients with ET. Treatment included chemotherapy, radiotherapy, and surgical
excision of tumor after induction therapy. PB samples were taken prospectively at
least 2 weeks after resection of tumor. Nested reverse-transcriptase polymerase
chain reaction (RT-PCR) followed by Southern blot was performed in all samples.
Resected tumors were reviewed for the degree of response to chemotherapy and
volume. Seventy-seven PB samples from 28 patients had EWS-FLI1/ERG transcripts.
In 11 patients, PB samples became negative with treatment, and, in 5 of them, the
samples remained negative throughout the study. Samples taken during progression
were always positive and, in 4 patients, became positive before progression was
clinically evident. All patients with transcripts other than EWS-FLI1 type 1 (n =
3) died from tumor progression. This is a sensitive assay to monitor circulating
tumor cells in Ewing tumors. The preliminary data suggest that progression is
preceded by positive samples and may be related to specific transcript types
CONTRIBUTIONS TO RICKETTSIOSES RESEARCH IN COLOMBIA (1917-1943), LUIS B. PATIÑO CAMARGO
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