Preparation, characterization and tests of incorporation in stem cells of superparamagnetic iron oxide

Superparamagnetic iron oxide nanoparticles (SPIONs) have been produced and used as contrast-enhancing agents in magnetic resonance imaging (MRI) for diagnostic use in a wide range of maladies including cardiovascular, neurological disorders, and cancer. The reasons why these SPIONs are attractive for medical purposes are based on their important and unique features. The large surface area of the nanoparticles and their manipulation through an external magnetic field are features that allow their use for carrying a large number of molecules such as biomolecules or drugs. In this scenario, the present work reports on the synthesis and characterization of SPIONs and in vitro MRI experiments to increase their capacity as probes for MRI applications on stem cells therapy. Initially, the SPIONs were prepared through the co-precipitation method using ferrous and ferric chlorides in acidic solution. The SPIONs were coated with two thiol molecules such as mercaptosuccinic acid (MSA) and cysteine (Cys) (molar ratio SPIONs: ligand = 1: 20), leading to the formation of a stable aqueous dispersion of thiolated nanoparticles (SH-SPIONs). The SH-SPIONs were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM). The results showed that the SH-SPIONs have a mean diameter of 14 nm and display superparamagnetic behavior at room temperature. Preliminary tests of incorporation of SH-SPIONs were evaluated stem cells. The results showed that the thiolated nanoparticles have no toxic effects for stem cells and successfully internalized and enhance the contrast in MRI6174th International Conference on Safe Production and Use of Nanomaterials (Nanosafe

Regulatory Response to Carbon Starvation in Caulobacter crescentus

Bacteria adapt to shifts from rapid to slow growth, and have developed strategies for long-term survival during prolonged starvation and stress conditions. We report the regulatory response of C. crescentus to carbon starvation, based on combined high-throughput proteome and transcriptome analyses. Our results identify cell cycle changes in gene expression in response to carbon starvation that involve the prominent role of the FixK FNR/CAP family transcription factor and the CtrA cell cycle regulator. Notably, the SigT ECF sigma factor mediates the carbon starvation-induced degradation of CtrA, while activating a core set of general starvation-stress genes that respond to carbon starvation, osmotic stress, and exposure to heavy metals. Comparison of the response of swarmer cells and stalked cells to carbon starvation revealed four groups of genes that exhibit different expression profiles. Also, cell pole morphogenesis and initiation of chromosome replication normally occurring at the swarmer-to-stalked cell transition are uncoupled in carbon-starved cells

Human Risk Assessment and Its Application to Nanotechnology: A Challenge for Assessors

International audienceno abstrac

Pérdida del rendimiento agroindustrial de la caña de azúcar asociada al retraso de la molienda en poscosecha

El estudio se realizó en la Facultad de Ciencias Agrarias, de la Universidad Nacional de Asunción, Filial Caazapá, periodo agrícola 2009. Para dicho estudio fue utilizada una parcela experimental de comparación de 10 variedades de caña de azúcar, en su segundo año de cultivo. El estudio incluyó cuatro tratamientos que son los tiempos de almacenamiento (0, 3, 6, y 9 días después de la cosecha) con 10 repeticiones, constituyéndose cada variedad en una repetición de los tratamientos en estudio. El objetivo fue determinar el efecto que ocasiona el retraso de la molienda después del corte en el rendimiento agrícola e industrial de la caña de azúcar. Las variables consideradas fueron: contenido de sólidos solubles, porcentaje de pol, porcentaje de pureza y peso de caña. Los resultados obtenidos muestran una pérdida gradual en peso de caña con el aumento del retraso de la molienda, hasta un 5,27% a los 9 días después del corte en relación al peso inicial; el contenido de sólidos solubles totales tiende a aumentar con la demora en el procesamiento, alcanzando su valor máximo (23%) a los 9 días después del corte, lo que equivale a un aumento del 16% en relación a lo observado en el primer día de corte (19,8%); el porcentaje de pol disminuyó gradualmente con el aumento del tiempo de almacenamiento, con un 12,97% a los 9 días después del corte; por último, se observó que la demora en el procesamiento de la caña disminuye el porcentaje de pureza hasta un 24% con 9 días de retraso

Roles of HIPK1 and HIPK2 in AML1- and p300-dependent transcription, hematopoiesis and blood vessel formation

Histone acetyltransferases (HATs) p300 and CREB-binding protein (CBP) function as co-activators for a variety of sequence-specific transcription factors, including AML1. Here, we report that homeodomain-interacting protein kinase-2 (HIPK2) forms a complex with AML1 and p300, and phosphorylates both AML1 and p300 to stimulate transcription activation as well as HAT activities. Phosphorylation of p300 is triggered by phosphorylated AML1 as well as by PU.1, c-MYB, c-JUN and c-FOS, and is inhibited by dominant-negative HIPK2. Phosphorylation of p300 and AML1 is impaired in Hipk1/2 double-deficient mouse embryos. Double-deficient mice exhibit defects in primitive/definitive hematopoiesis, vasculogenesis, angiogenesis and neural tube closure. These phenotypes are in part similar to those observed in p300- and CBP-deficient mice. HIPK2 also phosphorylates another co-activator, MOZ, in an AML1-dependent manner. We discuss a possible mechanism by which transcription factors could regulate local histone acetylation and transcription of their target genes

Downregulation of Bim, a Proapoptotic Relative of Bcl-2, Is a Pivotal Step in Cytokine-Initiated Survival Signaling in Murine Hematopoietic Progenitors

Two distinct signaling pathways regulate the survival of interleukin-3 (IL-3)-dependent hematopoietic progenitors. One originates from the membrane-proximal portion of the cytoplasmic domain of the IL-3 receptor (βc chain), which is shared by IL-3 and granulocyte-macrophage colony-stimulating factor and is involved in the regulation of Bcl-x(L) through activation of STAT5. The other pathway emanates from the distal region of the βc chain and overlaps with downstream signals from constitutively active Ras proteins. Although the latter pathway is indispensable for cell survival, its downstream targets remain largely undefined. Here we show that the expression of Bim, a member of the BH3-only subfamily of cell death activators, is downregulated by IL-3 signaling through either of two major Ras pathways: Raf/mitogen-activated protein kinase and the phosphatidylinositol 3-kinase/mammalian target of rapamycin. Akt/phosphokinase B does not appear to play a significant role in this regulatory cascade. Bim downregulation has important implications for cell survival, since enforced expression of this death activator at levels equivalent to those induced by cytokine withdrawal led to apoptosis even in the presence of IL-3. We conclude that Bim is a pivotal molecule in cytokine regulation of hematopoietic cell survival

Spectroscopy of high lying resonances in

We present the results of the 8Li(p,α)5He and 8Li(p,p)8Li reactions measured at the RIBRAS (Radioactive Ion Beams in Brazil) system. The experiment was realized in inverse kinematics using a thick [CH2]n polyethylene target and an incident 8Li beam, produced by RIBRAS. Using the thick target method, the complete excitation function could be measured between Ecm = 0.2 − 2.1 MeV, which includes the Gamow peak energy region. The excitation function of the 8Li(p,α)5He reaction, populating resonances between 16.888 and 19.0 MeV in 9Be, was obtained[1] and the resonances were fitted using R-matrix calculations. This study shed light on spins, parities, partial widths and isospin values of high lying resonances in 9Be. The measurement of the resonant elastic scattering 8Li(p,p)8Li populating resonances in the same energy region can constrain the resonance parameters. Preliminary results of the elastic scattering are also presented