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Search Results: 1 - 10 of 26911 matches for " RENé TORRES "
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Rese a de ""Los superhéroes no existen". Los migrantes mexicanos ante las primeras elecciones en el exterior" de Leticia Calderón Chelius
René TORRES-RUIZ
Migraciones internacionales , 2012,
Abstract:
Chemical Analysis of the Resinous Exudate Isolated from Heliotropium taltalense and Evaluation of the Antioxidant Activity of the Phenolics Components and the Resin in Homogeneous and Heterogeneous Systems
Brenda Modak,Macarena Rojas,René Torres
Molecules , 2009, DOI: 10.3390/molecules14061980
Abstract: H. taltalense (Phil.) Johnst. (Heliotropiaceae) is an endemic species of the northern coast of Chile that produces a resinous exudate that covers its foliar surface and stems. Its chemical composition was analyzed for the first time, and two aromatic geranyl derivatives: filifolinol and filifolinyl senecionate and three flavonoids – naringenin, 3-O-methylgalangin and 7-O-methyleriodictiol – were isolated. The antioxidant activity of the flavonoids and the resinous exudates was carried out by measuring the 1,1-diphenyl-2-picrylhydrazyl (DPPH) bleaching effect in ethanolic solution and in sodium dodecyl sulfate (SDS) micelles. The influence of the reaction medium was analyzed. The initial velocity reactions for the pure compounds and for the extract were higher in SDS media than in ethanolic solution. The velocity of reaction observed was interpreted in terms of the reaction medium environment in the micelle.
SEASONAL VARIATION OF THE FLAVONOIDS PINOCEMBRIN AND 3-O-METHYLGALANGIN, IN THE SURFACE COMPONENT MIXTURE (RESINOUS EXUDATES AND WAXY COATING) OF HELIOTROPIUM STENOPHYLLUM
MODAK,BRENDA; TORRES,RENé; URZúA,ALEJANDRO;
Journal of the Chilean Chemical Society , 2011, DOI: 10.4067/S0717-97072011000100002
Abstract: in this report we study the seasonal variation of the flavonoids pinocembrin and 3-o-methylgalangin in the surface component mixture (resinous exudate and waxy coating) of heliotropium stenophyllum. the quantitative analysis of the flavonoids was performed using high-performance liquid chromatography of samples collected monthly over a whole year. the results showed an increase in the spring and summer yield of surface components and a decrease during the winter. although the sum of pinocembrin and 3-o-methylgalangin did not follow a pattern related with hydric stress, uv radiation or high temperature during the year, a relationship between pinocembrin and 3-o-methylgalangin was found. on average during the months of september to august, excluding march, the amount of pinocembrin decreased wile the amount of 3-o-methylgalangin increased. the results suggest that the above compounds may play different ecophysiological functions during plant development and are consistent with the biosynthetic relationship between the two compounds.
SEASONAL VARIATION OF THE FLAVONOIDS PINOCEMBRIN AND 3-O-METHYLGALANGIN, IN THE SURFACE COMPONENT MIXTURE (RESINOUS EXUDATES AND WAXY COATING) OF HELIOTROPIUM STENOPHYLLUM
BRENDA MODAK,RENé TORRES,ALEJANDRO URZúA
Journal of the Chilean Chemical Society , 2011,
Abstract: In this report we study the seasonal variation of the flavonoids pinocembrin and 3-O-methylgalangin in the surface component mixture (resinous exudate and waxy coating) of Heliotropium stenophyllum. The quantitative analysis of the flavonoids was performed using high-performance liquid chromatography of samples collected monthly over a whole year. The results showed an increase in the spring and summer yield of surface components and a decrease during the winter. Although the sum of pinocembrin and 3-O-methylgalangin did not follow a pattern related with hydric stress, UV radiation or high temperature during the year, a relationship between pinocembrin and 3-O-methylgalangin was found. On average during the months of September to August, excluding March, the amount of pinocembrin decreased wile the amount of 3-O-methylgalangin increased. The results suggest that the above compounds may play different ecophysiological functions during plant development and are consistent with the biosynthetic relationship between the two compounds.
Canine Cutaneous Mast Cell Tumor: Biologic Behavior and Its Correlation with Prognostic Indicators  [PDF]
Sabrina dos Santos Costa Poggiani, Erika Maria Terra, Rafael Torres Neto, Mirela Tinucci Costa, Renée Laufer Amorim
Open Journal of Veterinary Medicine (OJVM) , 2012, DOI: 10.4236/ojvm.2012.24041
Abstract: Cutaneous mast cell tumor (MCT) shows a variable biological behavior in dogs and may present either as solitary masse that can be treated and cured with surgical removal or as a systemic metastatic and fatal disease. Histological grade, KIT pattern and proliferative index are typically prognostic factors in MCTs. In the present study, we have investigated correlation between clinical data (breed, age, gender, tumour location, tumor size, time before surgery, number of tumours, occurrence of metastasis and recurrence), cellular proliferation (Ki-67, mitotic index), intratumoural microvessel density (IMVD) and apoptotic index with the histological grade and KIT pattern. 28 tumors, from 20 dogs with cutaneous MCT were evaluated. There was association between histological grade, IMVD, tumor ulceration and number of tumors. A significant increase of Ki-67 expression and mitotic index was observed in MCTs with cytoplasmic KIT staining pattern. Patnaik histological grade system was related to mitotic index. Histological grade in canine cutaneous MCT should not be assessed as the only prognostic factor, but associated with KIT pattern, IMDV, cellular proliferation, presence of tumour ulceration, number of tumours, recurrences and metastases.
Study of the Chemical Composition of the Resinous Exudate Isolated from Heliotropium Sclerocarpum and Evaluation of the Antioxidant Properties of the Phenolic Compounds and the Resin
Brenda Modak,Melissa Salina,Jesús Rodilla,René Torres
Molecules , 2009, DOI: 10.3390/molecules14114625
Abstract: Heliotropium sclerocarpum Phil. (Heliotropiaceae) is a resinous bush that grows in the Atacama of northern Chile. The chemical composition of its resinous exudate was analyzed for the first time. One aromatic geranyl derivative: filifolinol (1), one flavanone: naringenin (2) and a new type of 3-oxo-2-arylbenzofuran derivative 3 were isolated and their structures were determined. The antioxidant activity of the phenolic compounds and resin was evaluated using the bleaching of DPPH radical method and expressed as fast reacting equivalents (FRE) and total reacting equivalents (TRE).
ANTIBACTERIAL ACTIVITY OF COMPOUNDS ISOLATED OF THE RESINOUS EXUDATE FROM HELIOTROPIUM SINUATUM ON PHYTOPATHOGENIC BACTERIA
MODAK,BRENDA; TORRES,RENé; WILKENS,MARCELA; URZúA,ALEJANDRO;
Journal of the Chilean Chemical Society , 2004, DOI: 10.4067/S0717-97072004000100001
Abstract: from the resinous exudates of heliotropium sinuatum have been isolated and characterized two compounds, pentaeicosanol 1 and 1-hydroxy-3-doeicosanone 2. those structures and previously isolated pure compounds have been tested in their antibacterial activity on phytopathogenic bacteria. ketone 2 and the flavonoid hesperetine 10 showed antibacterial activity on erwinia carotovora subsp. carotovora, while the flavonoid 3-o-methylgalangine 4 showed activity on clavibacter michiganensis subsp. michiganensis
Uso de Andropogon gayanus bajo diferentes cargas animales, en una sabana eólica del Capanaparo, estado Apure, Venezuela
Torres,René; Aparicio,Rafael; Astudillo,Luís; García,Espedito;
Zootecnia Tropical , 2007,
Abstract: abstract to evaluate andropogon gayanus with young animals in two seasons of the year, under the conditions of the savanna of the capanaparo, between august 1990 and may 1992, it was done an experiment in the ranch the mercedes, achaguas municipality, apure state, on five paddocks which were loaded by 0.5 (low), 1.0 (average), and 1.5 (high) au/ha, respectively. stocking rates in all the cases were established by three heifers indicatives of weight and a young bull grazing, which was withdrawn later to adjust the rates, to which it was taken estimations of the weight every two months. in equal frequency there were realized measurements of production of biomass by paddock, coverage, and height of the pasture, and establishment of tenors of crude protein, phosphorus, calcium, magnesium, copper, and zinc. the highest dm offer was obtained in the rainy season compared to drought, 11 and 9 t dm/ha/year, respectively. the pc contents were 53% higher in the rainy season (6.45%) than in the drought season (3.05%). the tenors of ca, mg, and cu in both seasons were within the normal limits and only the p and zn concentrations were below the critical level. the low stocking rate had the best animal response with 836 g/anim/d in relation to the average and high rates (613, and 652 g/anim/d) in the rainy season
Dinámica de componentes físico químicos del agua en las lagunas de abrevaderos en sabanas hiperestacionales de bancos, bajíos y esteros de Mantecal, estado Apure
Torres,René; Aparicio,Rafael; Astudillo,Luis; Carrasquel,José;
Zootecnia Tropical , 2009,
Abstract: in order to study the dynamics of physicochemicals components of water obtained from lagoons situated on physiographys of ?bancos, bajíos y esteros? that serve as watering places for cattle, samples from savannas of mantecal, apure state, venezuela were taken and measured between march - 2005 to april - 2007. results showed proverty of mineral elements for adecuate mineral nutrition, low electric conductivity and slightly acids ph, which in periods of draught had a tendency to neutrality. sodium, potassium, calcium cations and less frequent magnesium, presented greater values on the lagoons in the physiographys of ?esteros and bajíos? specially during the dry season. concentrations of sulfur and iron rise during the dry season, coinciding with reproductive season, this could induce metabolic disorder related to mineral nutrition of the herds
ANTIOXIDANT PROPERTIES OF LIGNANS AND FERULIC ACID FROM THE RESINOUS EXUDATE OF LARREA NITIDA
RENé TORRES,FRANCISCO URBINA,CLAUDIA MORALES,BRENDA MODAK
Journal of the Chilean Chemical Society , 2003,
Abstract: From the resinous exudate of twigs end leaves of Larrea nitida, two lignans nor isoguaiacine 1 and meso-nor-dihydroguaiaretic acid 2 and ferulic acid 3 were isolated. The antioxidant activities of resin and pure compounds were assesed by bleaching of the ABTS derived radical-cation
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