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

A reliable procedure for the preparation of graphene-boron nitride superlattices as large area (cm x cm) films on arbitrary substrates or powders (gram scale) and unexpected electrocatalytic properties

[EN] Herein, a reliable procedure for the preparation of graphene-boron nitride superlattices, either as films or powders, consisting of the pyrolysis at 900 degrees C of polystyrene embedded pre-formed boron nitride single sheets is reported. The procedure can serve to prepare large area films (cm x cm) of this superlattice on quartz, copper foil and ceramics. Selected area electron diffraction patterns at every location on the films show the occurrence of the graphene-boron nitride superlattice all over the film. The procedure can also be applied to the preparation of powdered samples on a gram scale. Comparison with other materials indicates that the superlattice appears spontaneously as the growing graphene sheets develop, due to the templating effect of pre-existing boron nitride single sheets. Since the characteristic boron nitride emission in the visible region is completely quenched in the superlattice configuration, it is proposed that fluorescence microscopy can be used as a routine technique to determine the occurrence of superlattice in large area films. Electrodes of this material show an unforeseen catalytic activity for oxygen reduction reaction and exhibit a decrease of the heterojunction-electrolyte interphase electrical resistance.Financial support by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa and CTQ-2015-69653-CO2-R1) is gratefully acknowledged. AR and AP thank the Spanish Ministry of Economy and Competitiveness for a postgraduate scholarship and a Ramon y Cajal research associate contract, respectively.Rendon-Patiño, A.; Doménech, A.; García Gómez, H.; Primo Arnau, AM. (2019). A reliable procedure for the preparation of graphene-boron nitride superlattices as large area (cm x cm) films on arbitrary substrates or powders (gram scale) and unexpected electrocatalytic properties. Nanoscale. 11(6):2981-2990. https://doi.org/10.1039/c8nr08377kS2981299011

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

Superior Electrocatalytic Activity of MoS2-Graphene as Superlattice

[EN] Evidence by selected area diffraction patterns shows the successful preparation of large area (cm x cm) MoS2/graphene heterojunctions in coincidence of the MoS2 and graphene hexagons (superlattice). The electrodes of MoS2/graphene in superlattice configuration show improved catalytic activity for H-2 and O-2 evolution with smaller overpotential of +0.34 V for the overall water splitting when compared with analogous MoS2/graphene heterojunction with random stacking.This research was funded by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa and CTQ2015-68653-CO2-R1) and Generalitat Valenciana (Prometeo 2017-083).Rendon-Patiño, A.; Domenech-Carbó, A.; Primo Arnau, AM.; García Gómez, H. (2020). Superior Electrocatalytic Activity of MoS2-Graphene as Superlattice. Nanomaterials. 10(5):1-9. https://doi.org/10.3390/nano10050839S1910

Band gap alignment of structured microporous graphitic carbons by N doping and its influence on photocatalytic overall water splitting

[EN] Hydrogen generation from water using solar light could be a process of paramount importance in the forthcoming decarbonized society. This reaction requires efficient photocatalysts based on earthabundant elements. Metal-free carbon semiconducting materials are very appealing in this regard. This manuscript shows that N-doping is a convenient strategy to increase the photocatalytic activity of microporous graphitic carbons obtained from the pyrolysis of a-, b- and g-cyclodextrins. These (N)C carbons exhibit enhanced photocatalytic activity for H2 generation in the presence of methanol with respect to their undoped analogs. The optimal (N)C material (pore size, 0.65 nm) was the one derived from a-cyclodextrin at a N content of 3.1%, achieving a H2 productivity of 1.8 mmol g1 at 4 h in the presence of methanol. These materials also exhibit photocatalytic activity for overall water splitting, although with lower efficiency than for H2 generation in the presence of sacrificial electron donors. The present results illustrate the tuning of band alignment by N-doping in the graphitic matrixFinancial support by the Spanish Ministry of Science and Innovation (Severo Ochoa and CTQ2018-98237-CO2-1) and Generalitat Valenciana (Prometeo 2017-083) is gratefully acknowledged. AR and AP thanks the Spanish Ministry of Economy and Competitiveness for a postgraduate scholarship and a Ramon y Cajal research associate contract, respectively.Rendon-Patiño, A.; Torres-Martí, F.; Primo Arnau, AM.; García Gómez, H. (2022). Band gap alignment of structured microporous graphitic carbons by N doping and its influence on photocatalytic overall water splitting. Sustainable Energy & Fuels. 6(9):2170-2178. https://doi.org/10.1039/D2SE00078D217021786

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

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