SEM and TEM evidence of mixed-layer illite-smectite formed by dissolutioncrystallization processes in continental Paleogene sequences in northwestern Argentina

In the northernmost Calchaquí Valley (Salta, Argentina), the Paleogene continental sediments show a transition from smectite, at the top, to R3 I-S (>90% illite) through R1 I-S (65–80% illite), in contrast to the remaining sectors, containing smectite up to the bottom. Samples at the base of the succession were characterized by high-quality step-scan X-ray diffraction (XRD), scanning electron microscopy (SEM) and analytical high-resolution transmission electron microscopy (HRTEM). Analysis by SEM demonstrated dissolution of primary phases (feldspars, micas and quartz) and crystallization of illite, I-S and kaolinite. As this alteration is not pervasive, an intermediate fluid/rock ratio could be inferred. The lattice-fringe images of the samples from upper parts of the sequence show abundant I1-rich areas, whereas in the lower parts of the sequence, illite packets and I3 I-S coexist and compositions evolve towards muscovite (tetrahedral-charge increase, principally compensated by Mgby-Al substitution in octahedral sites and by a slight decrease in Ca in interlayer sites). As burial temperatures were probably similar in all the samples, depth was not responsible for the illite formation at the bottom. The TEM textures suggest that illitization proceeded mainly by dissolution-crystallization. The active faults close to the northern Calchaquí Valley probably promoted the circulation of hot, deep fluids, favouring illitization

Evidence of cyclic climatic changes recorded in clay mineral assemblages from a continental Paleocene-Eocene sequence, northwestern Argentina

The continental Paleocene-Eocene sequence investigated in this study belongs to the Salta Group, deposited in an intracontinental rift, the Salta Basin (NW Argentina), that evolved from the lower Cretaceous to the middle Paleogene, and is subdivided into the Pirgua, the Balbuena and the Santa Barbara Subgroups. The Maíz Gordo Formation (200 m thick) is the middle unit of the Santa Bárbara Subgroup, deposited during late post-rift sedimentation. We studied the mineralogy of fine-grained horizons of this formation by X-ray diffraction and Scanning Electron Microscopy (SEM) in order to examine the connection between vertical changes in clay mineralogy in alluvial sediments and paleosols, and global paleoclimatic changes registered during the Paleogene. Paleosols vary from calcic vertisols in the lowermost levels, to inseptisols and gleysols in intermediate positions, to gleyed oxisols in the upper section, indicating increased chemical weathering through time. Clay mineral relative abundances vary with a general increase in kaolinite content from bottom to top. However, at one site there are significant variations in kaolinite/muscovite (Kln/Ms) that define five cycles of kaolinite abundance and Kln/Ms. that indicate cyclic patterns of paleoprecipitation and paleotemperature. These are interpreted as several short-lived hyperthermals during the Paleocene-early Eocene in the Southern Hemisphere, which correlate with well-established episodes of warmth documented from the Northern Hemisphere

Engineering donor mesenchymal cells with IL-7 hastens naive T cell recruitment in vitro and supports immunologic reconstitution after HSCT in NOD/SCID mice

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117: Naive and memory T regulatory cells respond to mesenchymal cells regulation

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Prompt dipole radiation in fusion reactions

The prompt gamma ray emission was investigated in the 16A MeV energy region by means of the 36,40Ar+96,92Zr fusion reactions leading to a compound nucleus in the vicinity of 132Ce. We show that the prompt radiation, which appears to be still effective at such a high beam energy, has an angular distribution pattern consistent with a dipole oscillation along the symmetry axis of the dinuclear system. The data are compared with calculations based on a collective bremsstrahlung analysis of the reaction dynamics

Rituximab vs mycophenolate and vs cyclophosphamide pulses for induction therapy of active lupus nephritis: A clinical observational study

Objective. We report the first comparison between rituximab (RTX) and either MMF or CYC pulses in the treatment of active LN. Methods. Fifty-four patients with active LN received three methylprednisolone pulses for 3 consecutive days followed by oral prednisone and RTX 1 g at days 3 and 18 (17 patients) or MMF 2-2.5 g/day (17 patients) or six CYC pulses (0.5 g every fortnight) (20 patients). At 4 months MMF, AZA or ciclosporin were associated to prednisone as a consolidation/maintenance therapy in all groups. The outcomes of the three groups were compared at 3 and 12 months. Results. Patients in the RTX group were older, had a longer duration of SLE and LN, had more renal flares, had higher activity and had higher chronicity indexes at renal biopsy than the other two groups. Four patients in each group had acute renal dysfunction and 3c50% had nephrotic syndrome. At 3 months, proteinuria was reduced by 50% in 58.8% of patients on RTX, in 64.7% on MMF and in 63.1% on CYC. At 12 months, complete remission was present in 70.6% of patients on RTX, in 52.9% on MMF, and in 65% on CYC. Partial remission was reached in 29.4% on RTX, 41.2% on MMF, and 25% on CYC. Conclusion. RTX seems to be at least as effective as MMF and CYC pulses in inducing remission. Considering that patients treated with RTX had more negative renal prognostic factors, this drug should be considered a viable alternative for the treatment of active LN

Localización espacial y caracterización cultural de sitios arqueológicos del Gran Chaco Meridional

Debido fundamentalmente a factores tectónicos, geomorfológicos y climáticos, la Región Chaqueña posee una importante diversidad interna. En todos estos ambientes, y a lo largo del tiempo, seguramente se han asentado distintos grupos humanos, aunque no puedan reconocerse aún secuencias amplias de ocupación y la información esté en proceso de análisis e integración. Hasta hace muy poco tiempo atrás, se hablaba solamente de un territorio compartido hacia la periferia con la Región de las Selvas Occidentales, la Región Chaco-Santiagueña y la Subárea del Nordeste argentino (González y Pérez, 1972), siendo casi una constante hacer referencia a su desarrollo cultural en vinculación con el Área Andina y/o Amazónica. También fue notorio que por la escasa información disponible, se haya generalizado la utilización del enfoque descriptivo-interpretativo de la etnografía para el análisis de los datos arqueológicos. A partir de 1985 en que se comenzó a ejecutar nuestro proyecto de investigación (Braunstein y col., 2002), fuimos abarcando territorio y desarrollando trabajos en forma extensiva antes que intensiva y localizada, destacando de este modo los cambios ocurridos en términos del espacio, lo cual nos mostró un espectro cultural multivariado correlacionable con los aspectos ambientales. Las investigaciones intensivas, realizadas hasta el momento sólo en algunos asentamientos, en particular en los ubicados en el extremo norte del Sector Central y en el Ribereño Paraguay-paranaense, nos llevan a una etapa que incluye la determinación de cambios desde una óptica temporal y un análisis ecológico más detallado, facilitando de este modo el planteo comparativo etnográfico-paleoetnográfico. Hoy, merced al incremento de los trabajos de campo, al análisis interdisciplinario de la problemática antropológica y al aporte de disciplinas complementarias biológicas y nobiológicas, podemos hablar de un ordenamiento de la información que, complementariamente con los datos aportados por la periferia, permiten vislumbrar entidad propia para la región. Sin lugar a dudas la obtención de cronologías absolutas para el Chaco Meridional es imperiosa y de ello depende dar marco temporal más preciso, aún no logrado por las dificultades encontradas para el procesamiento radiocarbónico de las muestras obtenidas en los sucesivos trabajos de campo. Este gran territorio para su mejor tratamiento ha sido segmentado fundamentalmente en base a criterios biogeográficos y culturales (Braunstein y col., ib.). De cada uno de los sectores establecidos y de los sitios identificados hasta el momento, surgen handicaps y caracterizaciones que los proponen en su potencial arqueológico a la espera de trabajos intensivos. Especial consideración, para la programación de esta segunda etapa, se tendrá de los caracteres aislados previamente y representativos del medio natural. De la información obtenida, a partir del análisis bibliográfico y de los resultados de nuestros propios trabajos en el terreno, surge la presente contribución como un intento de sistematizar todos los datos disponibles y actualizar de este modo la problemática arqueológica de la región. Obvia mente este mapa arqueológico se irá enriqueciendo con la recopilación de información édita e inédita, aún dispersa y en elaboración (Salceda y col., inéd.) ampliándose a medida que se extiendan y profundicen las investigaciones en el área.Facultad de Ciencias Naturales y Muse

Low-dose oral imatinib in the treatment of systemic sclerosis interstitial lung disease unresponsive to cyclophosphamide: a phase II pilot study.

NTRODUCTION: Pulmonary involvement represents a major cause of death of systemic sclerosis (SSc) patients. Recent data suggest that tyrosine kinase inhibitors, such as imatinib, may be a therapeutic option for SSc patients. However, preliminary published clinical trials were inconclusive about imatinib efficacy and showed side effects. The purpose of this study was to verify efficacy and tolerability of low-dose imatinib on interstitial lung disease in a cohort of SSc patients unresponsive to cyclophosphamide therapy. METHODS: Thirty consecutive SSc patients with active pulmonary involvement, unresponsive to cyclophosphamide, were treated with imatinib 200 mg/day for 6 months followed by a 6-month follow-up. A "good response" was defined as an increase of forced vital capacity (FVC) by more of 15% and/or increase of diffusing capacity of carbon monoxide (DLCO) >15% and PaO2 > 90% of initial value and high-resolution computed tomography (HRCT)-scan pattern unchanged or improved. RESULTS: Twenty-six patients completed the study. Three patients died and one patient was lost to follow-up. Four patients (15.32%) had a good response, 7 worsened and 15 had a stabilized lung disease. Overall, 19 (73.07%) patients had an improved or stabilized lung disease. After a 6-month follow-up, 12 (54.5%) of the 22 patients showed an improved or stabilized lung disease. CONCLUSIONS: Lung function was stabilized in a large proportion of patients unresponsive to cyclophosphamide therapy and a beneficial outcome emerged from the analysis of HRCT lung scans. There was no significant improvement of skin involvement, and the low dose was well tolerated. These data provide useful suggestions to design future randomized clinical trials for SSc therapeutics

Low-dose oral imatinib in the treatment of systemic sclerosis interstitial lung disease unresponsive to cyclophosphamide: a phase II pilot study

Introduction: Pulmonary involvement represents a major cause of death of systemic sclerosis (SSc) patients. Recent data suggest that tyrosine kinase inhibitors, such as imatinib, may be a therapeutic option for SSc patients. However, preliminary published clinical trials were inconclusive about imatinib efficacy and showed side effects. The purpose of this study was to verify efficacy and tolerability of low-dose imatinib on interstitial lung disease in a cohort of SSc patients unresponsive to cyclophosphamide therapy.Methods: Thirty consecutive SSc patients with active pulmonary involvement, unresponsive to cyclophosphamide, were treated with imatinib 200 mg/day for 6 months followed by a 6-month follow-up. A "good response" was defined as an increase of forced vital capacity (FVC) by more of 15% and/or increase of diffusing capacity of carbon monoxide (DLCO) > 15% and PaO2 > 90% of initial value and high-resolution computed tomography (HRCT)-scan pattern unchanged or improved.Results: Twenty-six patients completed the study. Three patients died and one patient was lost to follow-up. Four patients (15.32%) had a good response, 7 worsened and 15 had a stabilized lung disease. Overall, 19 (73.07%) patients had an improved or stabilized lung disease. After a 6-month follow-up, 12 (54.5%) of the 22 patients showed an improved or stabilized lung disease.Conclusions: Lung function was stabilized in a large proportion of patients unresponsive to cyclophosphamide therapy and a beneficial outcome emerged from the analysis of HRCT lung scans. There was no significant improvement of skin involvement, and the low dose was well tolerated. These data provide useful suggestions to design future randomized clinical trials for SSc therapeutics