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

Bias Dependence of the Depletion Layer Width in Semi-Insulating GaAs by Charge Collection Scanning Microscopy

A procedure for the evaluation of the depletion region width of a Schottky barrier diode made on semi-insulating materials has been assessed and applied to gallium arsenide nuclear detectors. This procedure, which makes use of the optical beam induced current method of charge collection scanning microscopy, allows the direct measurement of the depletion layer width. By taking into account the high resistivity of the material under examination and measuring the diode reverse current, it is possible to evaluate the actual voltage applied at the depletion layer boundaries. It was found that, at low actual bias values, the voltage dependence of the depletion layer follows the usual square root power law, while at increasing voltages, it changes into a linear behavior. An explanation in terms of deep trap effect and trap field-enhanced capture cross-section is proposed even though further work must be done to explain the space charge width dependence on bias applied in terms of the deep trap influence

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

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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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A phase II randomised trial of 5-fluorouracil with or without interferon alpha-2a in advanced colorectal cancer.

With the association of 5-fluorouracil (5-FU) and alpha-interferon (IFN), objective responses as high as 26 63% have been reported in untreated patients with advanced colorectal cancer. However, grade 3-4 toxicity has also been reported. We have conducted a prospective phase II randomised study comparing 5-FU to 5-FU + IFN, to investigate whether the addition of IFN to a weekly 5-FU regimen devoid of significant toxicity used at our institutions could improve the effectiveness of 5-FU while maintaining acceptable toxicity. Patients with histologically proven advanced colorectal carcinoma were randomised to receive 5-FU 500 mg m-2 intravenous (i.v.) bolus on days 1-5 followed by 5-FU 500 mg m-2 i.v. bolus weekly from day 15, with or without IFN alpha-2a intramuscularly (i.m.) 1.5 mU daily on days 6-12 and 3 mU i.m. daily thereafter. The treatment was administered on an outpatient basis. Response was evaluated every 3 months, and treatment continued until progression or after two consecutive judgements of stable disease. Response rate was the main end point of the study. Of 141 patients eligible, 72 were randomised to 5-FU alone (arm A) and 69 to 5-FU + IFN (arm B). Responses were 9/72 (12.5%) in arm A and 6/69 (8.7%) in arm B; complete responses were three in arm A and two in arm B. Progression-free survival (median 4 months) and survival (median 12 months) were identical in the two arms. Toxicity was almost absent in arm A and moderate in arm B, represented mainly by haematological toxicity (usually leucopenia). In conclusion, overall survival was good in both arms of treatment and toxicity was moderate. While the response rate with 5-FU alone was in accord with the literature data, response to 5-FU + IFN was lower than expected. At least at this dosage and schedule, the association of 5-FU and IFN is no better than 5-FU alone and is of no clinical interest

Pheno-genotypic and symbiotic characterization of isolated rhizobia of Desmanthus Virgatus (l.) Willd. In soils of the province of Jujuy (Argentina)

Las leguminosas forrajeras nativas presentan un gran potencial productivo y un ejemplo de ellas es Desmanthus virgatus de amplia distribución en el centro norte de Argentina. El objetivo del trabajo fue realizar una caracterización feno-genotípica y simbiótica de rizobios que forman nódulos en D. virgatus con vista hacia el uso sustentable integral de dicha leguminosa. Para ello, se estableció una colección de 17 aislamientos recuperados de suelos de Jujuy. La caracterización fenotípica permitió reconocer rizobios de crecimiento rápido que mostraron un desarrollo óptimo entre pH 5 y 8, temperaturas de 28 a 35°C, y en concentraciones de 1% (p/v) de NaCl. Se hallaron rizobios con capacidad de crecimiento en condiciones extremas de pH 9 y a 40°C. Los aislamientos se identificaron como pertenecientes a Ensifer spp. y los perfiles de amplificación de ADN genómico mostraron escasa diversidad genética. La inoculación de D. virgatus con la cepa 8L12.1 (Ensifer sp.) produjo incrementos de biomasa seca aérea de 73% en cámara de cultivo y 124% a campo respecto a las plantas sin inocular y sin fertilizar.Native forage legumes have great productive potential and an example of which is Desmanthus virgatus with a wide distribution in central and northern Argentina. The objective of the work was to carry out a pheno-genotypic and symbiotic characterization of rhizobia that form nodules in D. virgatus with a view to the integral sustainable use of said legume. For this, a collection of 17 isolates recovered from Jujuy soils was established. Phenotypic characterization allowed to recognize fast-growing rhizobia that showed an optimal development between pH 5 y 8, temperatures to 28 a 35°C, and in concentrations of 1% (w/v) of NaCl. Rhizobia with growth capacity were found under extreme conditions of pH 9 and at 40°C. The isolates were identified as belonging to Ensifer spp. and the genomic DNA amplification profiles showed little genetic diversity. The inoculation of D. virgatus with the strain 8L12.1 (Ensifer sp.) produced increases of 73% aerial dry biomass in the cultivation chamber and 124% in the field with respect to the uninoculated and unfertilized plants.Instituto de Biotecnologia y Biologia Molecula

Autologus peripheral stem cell transplantation in a patient with diffuse systemic sclerosis: our experience

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Raised levels of circulating endothelial cells in systemic sclerosis

OBJECTIVE: Circulating endothelial cells (CECs) have been described in different conditions with vascular injury. Vascular abnormalities play a key role in the pathogenesis of Systemic Sclerosis (SSc). The aim of our study was to look for the presence of CECs in SSc patients and to evaluate their clinical significance. METHODS: We studied 52 SSc patients and 40 healthy controls (HC). Five-parameter, 3-color flow cytometry was performed with a FACScan. CECs were defined as CD45 negative, CD31 and P1H12 positive, and activated CECs as CD45 negative and P1H12, CD62, or CD106 positive. RESULTS: Total and activated CEC counts were significantly higher in SSc patients when compared with HC and positively correlated with disease activity score. We found a significant association between CECs and disease activity; as regard with organ involvement, CEC number correlate with the severity of pulmonary hypertension. CONCLUSIONS: Raised counts of CECs may represent direct evidence of active vascular disease in SSc as regard as visceral involvement, the association between CECs and pulmonary hypertension suggest a relevant role for CECs as a marker of prominent endothelial involvement

Endothelial progenitor cells in systemic sclerosis: their possible role in angiogenesis

BACKGROUND: Recently, several studies have demonstrated the presence of circulating endothelial progenitors (CEPs) responsible for angiogenesis. Notably, these cells are able to migrate to ischemic tissues and differentiate in situ in mature endothelial cells. Aim of this study was to assess the presence of CEPs in the peripheral blood of patients with Sistemic Sclerosis (SSc) and evaluate their significance as an attempt of re-vascularization MATERIAL AND METHODS: Samples of peripheral blood from 40 healthy subjects and 56 patients with SSc were studied. Five-parameter, 3-color flow cytometry was performed with a FACScan. CEPs were defined as CD45 negative, CD34 and CD133 positive. In addition, plasma levels of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) were detected by commercial ELISA (R&D Systems). RESULTS: Levels of CEPs (CD133+/CD34+/CD45-) were significantly higher in patients with SSc in comparison to HC (P = 0.01). No correlation was found between CEPs and any clinical parameter of disease neither activity score. CEPs were significantly higher in the group of patients with early disease, while their number decreased in the late phases of disease. Plasma levels of VEGF, but not bFGF, were significantly higher in SSc in comparison to HC (P<0.001) but no correlation was found between VEGF concentrations and CEP number. CONCLUSIONS: The presence of CEPs in patients with SSc suggest that sclerodermic hypoxic tissues could induce the mobilization of bone-marrow derived cells in an attempt to provided new vessels, in the early phase of the disease, at least