The nucleotidohydrolases DCTPP1 and dUTPase are involved in the cellular response to decitabine

Decitabine (5-aza-2acute;-deoxycytidine, aza-dCyd) is an anticancer drug used clinically for the treatment of myelodysplastic syndromes and acute myeloid leukemia that can act as a DNA-demethylating or genotoxic agent in a dose-dependent manner. On the other hand, DCTPP1 and dUTPase are two "house-cleaning" nucleotidohydrolases involved in the elimination of non-canonical nucleotides. Here we show that exposure of HeLa cells to decitabine up-regulates the expression of several pyrimidine metabolic enzymes including DCTPP1, dUTPase, dCMP deaminase and thymidylate synthase thus suggesting their contribution to the cellular response to this anticancer nucleoside. We present several lines of evidence supporting that, in addition to the formation of aza-dCTP, an alternative cytotoxic mechanism for decitabine may involve the formation of aza-dUMP, a potential thymidylate synthase inhibitor. Indeed, dUTPase or DCTPP1 down-regulation enhanced the cytotoxic effect of aza-dCyd producing an accumulation of nucleoside triphosphates containing uracil as well as uracil misincorporation and double-strand breaks in genomic DNA. Moreover, DCTPP1 hydrolyzes the triphosphate form of decitabine with similar kinetic efficiency than its natural substrate dCTP and prevents decitabine-induced global DNA demethylation. The data suggest that the nucleotidohydrolases DCTPP1 and dUTPase are factors involved in the mode of action of decitabine with potential value as enzymatic targets to improve decitabine-based chemotherapy

More productive in vitro culture of Cryptosporidium parvum for better study of the intra- and extracellular phases

The great difficulties in treating people and animals suffering from cryptosporidiosis have prompted the development of in vitro experimental models. Due to the models of in vitro culture, new extracellular stages of Cryptosporidium have been demonstrated. The development of these extracellular phases depends on the technique of in vitro culture and on the species and genotype of Cryptosporidium used. Here, we undertake the molecular characterization by polymerase chain reaction-restriction fragment lenght polymorphism of different Cryptosporidium isolates from calves, concluding that all are C. parvum of cattle genotype, although differing in the nucleotide at positions 472 and 498. Using these parasites, modified the in vitro culture technique for HCT-8 cells achieving greater multiplication of parasites. The HCT-8 cell cultures, for which the culture had not been renewed in seven days, were infected with C. parvum sporozoites in RPMI-1640 medium with 10% IFBS, CaCl2 and MgCl2 1 mM at pH 7.2. Percentages of cell parasitism were increased with respect to control cultures (71% at 48 h vs 14.5%), even after two weeks (47% vs 1.9%). Also, the percentage of extracellular stages augmented (25.3% vs 1.1% at 96 h). This new model of in vitro culture of C. parvum will enable easier study of the developmental phases of C. parvum in performing new chemotherapeutic assays

Pediatric swallow assessment instruments: a report by speech and languages pathologist in Colombia and Chile

La prevalencia de usuarios pediátricos que presentan alteraciones en la deglución/ alimentación ha aumentado significativamente, por lo que realizar un proceso de evaluación sistemático, a usuarios ambulatorios y/u hospitalizados, con el uso de instrumentos estandarizados, puede evitar complicaciones asociadas. El objetivo de esta investigación fue identificar cuáles son las pruebas que conocen y usan los fonoaudiólogos en dos países de habla hispana: Colombia y Chile, para la valoración de la deglución en población pediátrica. Se trata de un estudio observacional de corte transversal, en el que participaron 36 fonoaudiólogos de ambos países, los que contestaron una encuesta de 23 ítems, previamente validada por juicio de expertos. El 55,6% (n=20) señaló que conocía pruebas de screening, el 63,89% (n=23) conocía pruebas de evaluación clínica (no instrumentales o subjetivas), el 100% conocía pruebas instrumentales (objetivas) y sólo el 11% (n=4) conocían pruebas de calidad de vida. Se evidenció de forma general dificultad en la clasificación de las pruebas y un mayor uso de pruebas no estandarizadas, lo que sugiere una necesidad disciplinar en cuanto a la formación sobre instrumentos de medición y evaluación, que permitan la identificación, selección y comprensión analítica de dichos instrumentosThe prevalence of pediatric users with swallowing / feeding disorders has increased significantly, so carrying out a systematic evaluation process for outpatient and / or hospitalized users, with the use of standardized instruments, can avoid associated complications. The objective of this research was to identify which tests are known and used by Speech-Language Therapist in two Spanish-speaking countries: Colombia and Chile, for the assessment of swallowing in the pediatric population. This is a cross-sectional observational study, in which 36 Speech-Language Pathologists from both countries participated, who answered a survey of 23 items, previously validated by expert judgment. 55.6% (n= 20) indicated that they knew screening tests, 63.89% (n = 23) knew clinical evaluation tests (non-instrumental or subjective), 100% knew instrumental tests (objective) and only 11% (n = 4) knew quality of life tests. Difficulty in the classification of the tests and a greater use of non-standardized tests was generally evidenced, which allows their identification, selection and analytical understandin

Graphene Synthesis Using a CVD Reactor and a Discontinuous Feed of Gas Precursor at Atmospheric Pressure

The present work shows a new method in order to cost-effectively achieve the synthesis of graphene by Chemical Vapor Deposition (CVD). Unlike most usual processes, where precursors such as argon, H2, CH4, and high purity copper foil are used, the proposed method has replaced the previous ones by N2, N2 (90%) : H2 (10%), C2H2, and electrolytic copper (technical grade) since the use of industrialized precursors helps reduce production costs. On the other hand, the process was modified from a continuous flow system with vacuum to a discontinuous one at atmospheric pressure, eliminating the use of vacuum pump. In addition, this modification optimized the consumption of gases, which reduced the waste and the emission of pollutant gases into the atmosphere. Graphene films were grown under different gas flowrates and temperatures. Then, the obtained material was characterized by TEM, Raman spectroscopy, and AFM, confirming the presence of few graphene layers. In brief, the growth time was reduced to six minutes with acetylene as a carbon precursor at 1000°C and at atmospheric pressure, with a flow rate of 30 sccm. Finally, the reported conditions can be used for the synthesis of good quality graphene films in industrial applications

Tuning the electronic and magnetic properties of 2D g-GaN by H adsorption: An ab-initio study

We have theoretically studied the structural, electronic and magnetic properties of the hydrogen adsorption on a honeycomb gallium-nitride two-dimensional monolayer (2D g-GaN). Results indicate that the band gap energy can be systematically tuned by the hydrogen coverage on the 2D g-GaN in the diluted limit. In addition, a total magnetic moment can be induced in the 2D g-GaN by hydrogen adsorption due to s-p interaction and band structure effects. Although hydrogen adsorption on top of nitrogen atoms shows the most stable energy in the 2D g-GaN, the most stable ferromagnetism -with a nonzero magnetic moment-is obtained when hydrogen is adsorbed on top of Ga atoms. These results indicate that H adatoms on the 2D g-GaN systems could be a potential candidate for future spintronic applications