Cell death induced by the application of alternating magnetic fields to nanoparticle-loaded dendritic cells

In this work, the capability of primary, monocyte-derived dendritic cells (DCs) to uptake iron oxide magnetic nanoparticles (MNPs) is assessed and a strategy to induce selective cell death in these MNP-loaded DCs using external alternating magnetic fields (AMFs) is reported. No significant decrease in the cell viability of MNP-loaded DCs, compared to the control samples, was observed after five days of culture. The amount of MNPs incorporated into the cytoplasm was measured by magnetometry, which confirmed that 1 to 5 pg of the particles were uploaded per cell. The intracellular distribution of these MNPs, assessed by transmission electron microscopy, was found to be primarily inside the endosomic structures. These cells were then subjected to an AMF for 30 min, and the viability of the blank DCs (i.e., without MNPs), which were used as control samples, remained essentially unaffected. However, a remarkable decrease of viability from approximately 90% to 2-5% of DCs previously loaded with MNPs was observed after the same 30 min exposure to an AMF. The same results were obtained using MNPs having either positive (NH2+) or negative (COOH-) surface functional groups. In spite of the massive cell death induced by application of AMF to MNP-loaded DCs, the amount of incorporated magnetic particles did not raise the temperature of the cell culture. Clear morphological changes at the cell structure after magnetic field application were observed using scanning electron microscopy. Therefore, local damage produced by the MNPs could be the main mechanism for the selective cell death of MNP-loaded DCs under an AMF. Based on the ability of these cells to evade the reticuloendothelial system, these complexes combined with an AMF should be considered as a potentially powerful tool for tumour therapy.Comment: In Press. 33 pages, 11 figure

Application of magnetically induced hyperthermia on the model protozoan Crithidia fasciculata as a potential therapy against parasitic infections

Magnetic hyperthermia is currently an EU-approved clinical therapy against tumor cells that uses magnetic nanoparticles under a time varying magnetic field (TVMF). The same basic principle seems promising against trypanosomatids causing Chagas disease and sleeping sickness, since therapeutic drugs available display severe side effects and drug-resistant strains. However, no applications of this strategy against protozoan-induced diseases have been reported so far. In the present study, Crithidia fasciculata, a widely used model for therapeutic strategies against pathogenic trypanosomatids, was targeted with Fe_{3}O_{4} magnetic nanoparticles (MNPs) in order to remotely provoke cell death using TVMFs. The MNPs with average sizes of d approx. 30 nm were synthesized using a precipitation of FeSO_{4}4 in basic medium. The MNPs were added to Crithidia fasciculata choanomastigotes in exponential phase and incubated overnight. The amount of uploaded MNPs per cell was determined by magnetic measurements. Cell viability using the MTT colorimetric assay and flow cytometry showed that the MNPs were incorporated by the cells with no noticeable cell-toxicity effects. When a TVMF (f = 249 kHz, H = 13 kA/m) was applied to MNP-bearing cells, massive cell death was induced via a non-apoptotic mechanism. No effects were observed by applying a TVMF on control (without loaded MNPs) cells. No macroscopic rise in temperature was observed in the extracellular medium during the experiments. Scanning Electron Microscopy showed morphological changes after TVMF experiments. These data indicate (as a proof of principle) that intracellular hyperthermia is a suitable technology to induce the specific death of protozoan parasites bearing MNPs. These findings expand the possibilities for new therapeutic strategies that combat parasitic infections.Comment: 9 pages, four supplementary video file

Lesions of pemphigus vulgaris on irradiated skin

Summary Pemphigus vulgaris (PV) is an autoimmune blistering disease produced by IgG autoantibodies against desmoglein (Dsg)3. Lesions on the skin and mucosa can, in rare cases, be induced by radiotherapy. We report a patient with a history of microprolactinoma and PV, who had only oral lesions from the beginning of her illness but 2 months after treatment with radiotherapy for a breast neoplasia, developed skin lesions limited to the irradiated area. Over the following few months, she also developed autoantibodies against Dsg

Pattern formation from consistent dynamical closures of uniaxial nematic liquid crystals

Pattern formation in uniaxial polymeric liquid crystals is studied for different dynamic closure approximations. Using the principles of mesoscopic non-equilibrium thermodynamics in a mean-field approach, we derive a Fokker-Planck equation for the single-particle non-homogeneous distribution function of particle orientations and the evolution equations for the second and fourth order orientational tensor parameters. Afterwards, two dynamic closure approximations are discussed, one of them considering the relaxation of the fourth order orientational parameter and leading to a novel expression for the free-energy like function in terms of the scalar order parameter. Considering the evolution equation of the density of the system and values of the interaction parameter for which isotropic and nematic phases coexist, our analysis predicts that patterns and traveling waves can be produced in lyotropic uniaxial nematics even in the absence of external driving.Comment: 34 pages, 7 figure

Suppression of Tc in the (Y0.9Ca0.1)Ba2Cu4-xFexO8 system

In this paper, the effects produced by the iron substitutions in the (Y0.9Ca0.1)Ba2Cu4-xFexO8 system on the superconducting and structural properties are studied. The Rietveld fit of the crystal structure and Mossbauer spectroscopy results of (Y0.9Ca0.1)Ba2Cu4-xFexO8 samples indicate that, the iron atoms occupy the Cu(1) sites of the (Cu-O)2 double chain in fivefold coordination at low iron concentrations. Besides at high iron concentrations the iron atoms occupy the Cu(1) sites of single Cu-O chainss and Cu(2) sites in the CuO2 planes of the (Y0.9Ca0.1)Ba2Cu4-xFexO8 phase with structural defects. Simultaneouly, as iron concentration increases, a faster decrease of Tc is observed in this material comapred with the YBa2Cu3-xFexO7-y system. According to the charge transfer model proposed for YBa2Cu4O8 under pressure, the decrease in the Cu(1)-O(4) bond length in parallel to the increase in the Cu(2)-O(4) bond length may affect the charge transfer mechanism leading to the suppression of Tc.Comment: submitted to Journal of Physics: Condensed Matter on 12 October 2001, 8 figures, 2 tables, 9 page

Behaviour of local selections of <i>Eucalyptus viminalis</i> Labill.; australian origins of <i>E.viminalis, E.dunnii</i> Maiden., <i>E.ovata</i> Labill. and <i>E.viminalis</i> local commercial provenance, in Lobos, Buenos Aires Province, Argentine

El objetivo de este trabajo fue comparar las progenies de las selecciones de árboles pertenecientes a rodales de Eucalyptus viminalis ubicados en la Provincia de Buenos Aires, productos comerciales locales de E.viminalis, y orígenes especí­ficos australianos del género Eucalyptus sugeridos y suministrados por CSIRO (División of Forestry and Forest Products. Australia) de acuerdo a las características edafo-climáticas del sitio de la prueba (el material recomendado correspondió a E. viminalis, E. dunnii y E.ovata). El ensayo fue implantado en Lobos, Provincia de Buenos Aíres, República Argentina a los: 35° 10' Latitud Sud; 59°07' Longitud Oeste; 50 metros sobre el nivel del mar (m snm). Comparando los resultados de los tratamientos y contraponiéndolos con otros similares de la región, las procedencias locales seleccionadas pueden ser conside­radas como un recurso seminal a tener en cuenta en los futuros planes de desarrollo de la zona. La estabilidad del comportamiento de las mismas y su eventual identificación como «razas locales», sugieren su posible incorporación a los planes de mejoramiento genético. E.dunnii, pese a su restringida área de distribución, presenta un disímil comportamiento entre los orígenes probados. E.ovata no puede descartarse teniendo en cuenta lo sucedido en las otras especies, por lo tanto deben probarse otros orígenes. Mientras se continua la introducción de especies, orígenes y procedencias, la superioridad de las selecciones locales sobre los productos utilizados comercialmente en la zona, hace que las primeras se constituyan en el nivel de referencia para fijar las respuestas mínimas de los materiales importados y suministrar al productor recursos con cierto grado de mejora.The objective of this work was to compare the progenies of the selections of trees belonging to E.viminalis stands loeated in Buenos Aires province, with australian origins of this species and of E.dunnii and E.ovata in respect of local commercial Products of E.viminalis.The australian material was provided by CSIRO (División of Forestry and Forest Products, Australia) in accordance with climatic and edaphic characteristics of the expermental site. The trial was situated in Lobos, Buenos Aires province, Argentine at 35° 10' South latitude, 59°07' West longitude, 50m. Comparing the treatment results and contrasting them with other similar ones of the región, the local provenance rightly selected can be considered as a seminal resource worthy to be taken into account in the future plans for the zone developmentThe behaviour stability of the local provenances selections and their identification as «local races- suggest the possibility of their incorporation to the genetic improvement plans.E.dunnii, in spite of its restricted native distribution area, presents dissimilar behaviours in its tested origins. E.ovata can't be discarded taking into account what happened to the other species, therefore other origins should be tested. While the introduction of species, origins and provenances continue, local selections can constitute a reference level to establish the importad material mínimal responses and to provide the grower with material of a certain level of improvement.Facultad de Ciencias Agrarias y Forestale

Characterization of the spoilage microbiota of hake fillets packaged under a modified atmosphere (MAP) rich in CO2 (50% CO2/50% N2) and stored at different temperatures

The aim of this study was to characterize the spoilage microbiota of hake fillets stored under modified atmospheres (MAP) (50% CO2/50% N2) at different temperatures using high-throughput 16S rRNA gene sequencing and to compare the results with those obtained using traditional microbiology techniques. The results obtained indicate that, as expected, higher storage temperatures lead to shorter shelf-lives (the time of sensory rejection by panelists). Thus, the shelf-life decreased from six days to two days for Batch A when the storage temperature increased from 1 to 7 °C, and from five to two days—when the same increase in storage temperature was compared—for Batch B. In all cases, the trimethylamine (TMA) levels measured at the time of sensory rejection of hake fillets exceeded the recommended threshold of 5 mg/100 g. Photobacterium and Psychrobacter were the most abundant genera at the time of spoilage in all but one of the samples analyzed: Thus, Photobacterium represented between 19% and 46%, and Psychrobacter between 27% and 38% of the total microbiota. They were followed by Moritella, Carnobacterium, Shewanella, and Vibrio, whose relative order varied depending on the sample/batch analyzed. These results highlight the relevance of Photobacterium as a spoiler of hake stored in atmospheres rich in CO2. Further research will be required to elucidate if other microorganisms, such as Psychrobacter, Moritella, or Carnobacterium, also contribute to spoilage of hake when stored under MAP

Eco-innovative possibilities for improving the quality of thawed cod fillets using high-power ultrasound

In order to improve the quality of thawed cod fillets and minimize the impact of processing, an extended hydration phase is applied in the fishery product industry in order to recover the water lost during freezing and thawing. Such long phases not only compromise productivity, but increase the chances of microbial growth in fish. Ultrasound (US) is a technology that could reduce these long hydration times, thanks to its capacity to improve mass-transfer processes, thereby limiting the development of fish microbiota. This investigation studies the effect of different US intensities (25 kHz, 29.4 W/kg to 2.9 W/kg, 113.7 to 15.3 W) on weight gain (WG) in the hydration process of cod fillets. The influence of the hydration medium's pH (from pH 8.5 to 10.5) in combination with US was likewise evaluated. Microbiological and sensory analyses were carried out at the end of the hydration process in order to evaluate its impact. The higher the applied US power, the lower was the WG. US intensities of 2.9 W/kg produced the highest increments in WG (18.6%), reducing hydration time by 33% and thereby achieving the same hydration values as in control samples. The combination of US with a controlled pH of 8.5 permitted to shorten hydration time by an additional day, and also led to improved microbial quality in comparison with control samples. Sensorial analyses indicated that after 5 d of hydration, Quality Index Method (QIM) values were better than those obtained for control samples after 5 and 7 d. Specifically, color and gaping were the sensorial attributes of cod fillets better protected with the application of US

Susceptibilidad a Septoria musiva de híbridos inter e intraespecíficos de Populus spp. implantados en dos micrositios de la Pampa Húmeda Argentina

En los álamos, una de las enfermedades con mayor influencia en la cantidad y calidad de la madera producida es la cancrosis o r i g i n a d a p o r S e p t o r i a m u s i v a P e c k . El objetivo del trabajo fue determinar en clones híbridos de álamos (Populus spp.) la incidencia y la severidad de la enfermedad producida por Septoria, en dos micrositios de un mismo sitio regional, en Alberti, Buenos Aires, Argentina. Los clones utilizados fueron obtenidos de cruzamientos intraespecíficos de Populus deltoides e interespecíficos de P. deltoides x P. nigra (= P. x canadensis). Se determinó la susceptibilidad a la enfermedad para cada clon/micrositio mediante la estimación de la incidencia, del número de cancros en guías y ramas, y la severidad de daños (ID). Los híbridos inter e intraespecíficos de P. deltoides presentaron respuesta clonal diferencial en la susceptibilidad a la cancrosis en ambas situaciones geomórficas: los híbridos provenientes de cruzamientos intraespecíficos resultaron resistentes, y los provenientes de cruzamientos interespecíficos susceptibles a la enfermedad. Las diferencias significativas entre clones, determinadas para el número de lesiones totales por posición en ambas situaciones geomórficas, no determinaron ID diferentes. El número de cancros identificados en cada posición constituye una herramienta de estimación de la susceptibilidad clonal a la cancrosis más exacta, teniendo en cuenta que los mayores perjuicios ocurren cuando las lesiones se presentan en las guías.En los álamos, una de las enfermedades con mayor influencia en la cantidad y calidad de la madera producida es la cancrosis o r i g i n a d a p o r S e p t o r i a m u s i v a P e c k . El objetivo del trabajo fue determinar en clones híbridos de álamos (Populus spp.) la incidencia y la severidad de la enfermedad producida por Septoria, en dos micrositios de un mismo sitio regional, en Alberti, Buenos Aires, Argentina. Los clones utilizados fueron obtenidos de cruzamientos intraespecíficos de Populus deltoides e interespecíficos de P. deltoides x P. nigra (= P. x canadensis). Se determinó la susceptibilidad a la enfermedad para cada clon/micrositio mediante la estimación de la incidencia, del número de cancros en guías y ramas, y la severidad de daños (ID). Los híbridos inter e intraespecíficos de P. deltoides presentaron respuesta clonal diferencial en la susceptibilidad a la cancrosis en ambas situaciones geomórficas: los híbridos provenientes de cruzamientos intraespecíficos resultaron resistentes, y los provenientes de cruzamientos interespecíficos susceptibles a la enfermedad. Las diferencias significativas entre clones, determinadas para el número de lesiones totales por posición en ambas situaciones geomórficas, no determinaron ID diferentes. El número de cancros identificados en cada posición constituye una herramienta de estimación de la susceptibilidad clonal a la cancrosis más exacta, teniendo en cuenta que los mayores perjuicios ocurren cuando las lesiones se presentan en las guías