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Search Results: 1 - 10 of 387526 matches for " Miriam C Ortiz L "
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Comparación de los métodos PetrifilmTM coliformes y Número Más Probable (NMP) para la determinación de coliformes fecales en muestras de queso blanco
Ortiz L,Miriam C; Ríos de S,Manuela;
Revista del Instituto Nacional de Higiene Rafael Rangel , 2006,
Abstract: fecal coliform belong to an important group of sanitary quality indicator microorganisms in food, mainly constituted for escherichia coli, considerated as indicators of recent fecal contamination, that is why it is very important to investigate their presence and to detect their population in food rapidly. the objetive of this study was to compare the most probable number (npm) method for fecal coliform determination, according to venezuelan standard covenin no 1104-96, with the coliform petrifilmtm 3mtm plates, incubated in circulating thermostatically - controlled water bath (pba) at 45 ± 0,2 ° c for 24 ± 2 hours and in a circulating air incubator at 44 ± 1° c for 24 ± 2 hours (pes), according to the recommendation of association francoise of normalization, paris (afnor) and 3mtm corporation. forty-two white cheese samples were analyzed using both methods mentioned above. they were dispensed at the same time with decimal dilutions of the samples. data generated were subjected to correlation of related samples (sps 7.5 version) and the correlation coefficients (r) were obtained; r = 0.952 nmp and pes; r = 0.944 nmp and pba. it is interesting to observe a good correlation between the methodologies in their different forms for fecal coliform determination in white cheese. coliform petrifilmtm plates incubated at the optimal temperature of coliform fecal culture represent a rapid alternative and reliable method for the assessment of fecal coliform population in white cheese.
Comparación de los métodos PetrifilmTM coliformes y Número Más Probable (NMP) para la determinación de coliformes fecales en muestras de queso blanco Comparison study between the coliform PetrifilmTM and the Most Probable Number methods for the assessment of fecal coliforms in white cheese
Miriam C Ortiz L,Manuela Ríos de S
Revista del Instituto Nacional de Higiene Rafael Rangel , 2006,
Abstract: Los coliformes fecales son un grupo importante de microorganismos indicadores de inocuidad en alimentos, constituido principalmente por Escherichia coli, el cual es considerado como indicador de contaminación reciente de origen fecal, por ello la importancia de investigar su presencia y determinar rápidamente el nivel poblacional en alimentos. Este trabajo tiene como objetivo comparar el método tradicional Número Más Probable (NMP) para la determinación de coliformes fecales, según Norma Venezolana Covenin No 1104-96 con el método de placas rehidratables PetrifilmTM 3M coliformes incubadas en ba o de agua circulante (PBA) a 45 ± 0,2°C por 24 ± 2 horas y en estufa con aire circulante 44 ± 1°C por 24 ± 2 horas (PES) de acuerdo con lo recomendado por la Asociación Francesa de Normalización (AFNOR) y la Corporación 3M. Se analizaron un total de 42 muestras de queso blanco aplicando ambas metodologías, dispensando simultáneamente diluciones seriadas de las muestras. Para el análisis estadístico se realizó una correlación de muestras relacionadas (SPS versión 7,5), obteniéndose los siguientes resultados r = 0,952 entre NMP y PES y r = 0,944 entre NMP y PBA; lo que indica una buena correlación positiva entre ambas metodologías en sus diferentes modalidades para la determinación de coliformes fecales en muestras de queso blanco. Se concluye que las placas PetrifilmTM coliformes incubadas a la temperatura óptima de crecimiento de dichos microorganismos es un método alternativo, rápido y confiable para la determinación del nivel de coliformes fecales en queso blanco. Fecal coliform belong to an important group of sanitary quality indicator microorganisms in food, mainly constituted for Escherichia coli, considerated as indicators of recent fecal contamination, that is why it is very important to investigate their presence and to detect their population in food rapidly. The objetive of this study was to compare the Most Probable Number (NPM) method for fecal coliform determination, according to Venezuelan standard COVENIN No 1104-96, with the coliform PetrifilmTM 3M TM plates, incubated in circulating thermostatically - controlled water bath (PBA) at 45 ± 0,2 ° C for 24 ± 2 hours and in a circulating air incubator at 44 ± 1° C for 24 ± 2 hours (PES), according to the recommendation of Association Francoise of Normalization, Paris (AFNOR) and 3M TM corporation. Forty-two white cheese samples were analyzed using both methods mentioned above. They were dispensed at the same time with decimal dilutions of the samples. Data generated were subjected to correlation of re
Sol-Gel Silica Matrix as Reservoir for Controlled Release of Paracetamol: Characterization and Kinetic Analysis  [PDF]
Tessy López, Mayra álvarez, Paola Ramírez, Gustavo Jardón, Miriam López, Guadalupe Rodriguez, Itzel Ortiz, Octavio Novaro
Journal of Encapsulation and Adsorption Sciences (JEAS) , 2016, DOI: 10.4236/jeas.2016.62005
Abstract: Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) are usually suitable candidates for the development of drug delivery devices. Sol-gel chemistry represents an easy method to obtain porous silica nanoparticles. Mesoporous silica nanomaterials have been widely used for drug delivery purposes. In this work we synthesized silica based materials using two molar alkoxide:water ratios 1:4 and 1:8, incorporating paracetamol to develop a nano-sized matrix for controlled release purposes. The samples exhibited different values for surface area, porosity, particle size and distinct punctual defects. Infrared and UV-visible spectroscopic studies were carried out to demonstrate the effect of water concentration and the adequate incorporation of paracetamol molecules. Nitrogen adsorption characterization was realized and the estimated BET surface values were from 532 to 825 m2/g. Kinetic analysis of drug release profiles was performed using the hyperbola model. Transmission electron micrographs showed that all the materials formed aggregates of small particles with size between 10 - 60 nm. Mesoporous SiO2 materials were proved to be a suitable system for controlled release of paracetamol.
Cervical cancer cell lines expressing NKG2D-ligands are able to down-modulate the NKG2D receptor on NKL cells with functional implications
Miriam I Jimenez-Perez, Luis F Jave-Suarez, Pablo C Ortiz-Lazareno, Alejandro Bravo-Cuellar, Oscar Gonzalez-Ramella, Adriana Aguilar-Lemarroy, Georgina Hernandez-Flores, Ana L Pereira-Suarez, Adrian Daneri-Navarro, Susana del Toro-Arreola
BMC Immunology , 2012, DOI: 10.1186/1471-2172-13-7
Abstract: We demonstrate that NKG2D expressed on NKL cells is down-modulated by direct cell contact with cervical cancer cell lines HeLa, SiHa, and C33A, but not with non-tumorigenic keratinocytes (HaCaT). Moreover, this down-modulation had functional implications. We found expression of NKG2D-ligands in all cervical cancer cell lines, but the patterns of ligand distribution were different in each cell line. Cervical cancer cell lines co-cultured with NKL cells or fresh NK cells induced a marked diminution of NKG2D expression on NKL cells. Additionally, the cytotoxic activity of NKL cells against K562 targets was compromised after co-culture with HeLa and SiHa cells, while co-culture with C33A increased the cytotoxic activity of the NKL cells.Our results suggest that differential expression of NKG2D-ligands in cervical cancer cell lines might be associated with the down-modulation of NKG2D, as well as with changes in the cytotoxic activity of NKL cells after cell-cell contact with the tumor cells.Cervical cancer represents the third most commonly diagnosed cancer and the fourth leading cause of cancer-related deaths in women worldwide [1]. Human papillomavirus (HPV) infection is the most important risk factor for cervical cancer development [2,3]; persistence of high-risk HPV infection leads to premalignant lesions and may ultimately lead to cervical cancer in a multistep process [4,5]. The first line of defense against HPV in early infection is the innate immune system, which plays a crucial role in viral clearance [6].Natural killer (NK) cells are an important arm of the innate immune system directly involved in the spontaneous recognition and lysis of virus-infected and tumor cells. NK cells are endowed with potent cytotoxic activity, and they can also produce several cytokines, such as IFN-γ, TNF-α, GM-CSF, IL-5, and IL-8 [7-10]. Evidence is also accumulating for the crucial role of NK cells in tumor immunosurveillance [11].NK cell activity is finely regulated by an exqui
Neural correlates and neural computations in posterior parietal cortex during perceptual decision-making
Alexander C. Huk,Miriam L. R. Meister
Frontiers in Integrative Neuroscience , 2012, DOI: 10.3389/fnint.2012.00086
Abstract: A recent line of work has found remarkable success in relating perceptual decision-making and the spiking activity in the macaque lateral intraparietal area (LIP). In this review, we focus on questions about the neural computations in LIP that are not answered by demonstrations of neural correlates of psychological processes. We highlight three areas of limitations in our current understanding of the precise neural computations that might underlie neural correlates of decisions: (1) empirical questions not yet answered by existing data; (2) implementation issues related to how neural circuits could actually implement the mechanisms suggested by both extracellular neurophysiology and psychophysics; and (3) ecological constraints related to the use of well-controlled laboratory tasks and whether they provide an accurate window on sensorimotor computation. These issues motivate the adoption of a more general “encoding-decoding framework” that will be fruitful for more detailed contemplation of how neural computations in LIP relate to the formation of perceptual decisions.
Disfun??o erétil: um marcador para altera??es da perfus?o miocárdica?
Ortiz, Juarez;Ortiz, Sergio Tranchesi;Monaco, Claudia Gianini;Yamashita, Cristina Harumi;Moreira, Miriam Cássia Mendes;Monaco, Carlos Alberto F.;
Arquivos Brasileiros de Cardiologia , 2005, DOI: 10.1590/S0066-782X2005001700003
Abstract: objective: to study the correlation between erectile dysfunction (ed) and myocardial perfusion impairment in men with suspected or diagnosed coronary artery disease (cad). methods: in this prospective study a self-administered iief-5 questionnaire was answered by 287 patients that underwent myocardial perfusion imaging under both resting and stress condition with technetium-99m sestamibi, through gated spect nuclear scintigraphy technique, before and after physical or pharmacological stress. results: some degree of erectile dysfunction (group ed+) was found in 137 (47.8%) patients and in these, age was significantly higher (60.60±9.84 vs 50.67±9.94 - p<0.001)) than in those without erectile dysfunction (group ed-). in the ed+ group, it was observed a higher prevalence of hypertension, diabetes, myocardial infarction (mi) and percutaneous coronary angioplasty (pcta). regardless of the age factor, ed+ patients also presented higher occurrence of myocardial perfusion impairment (necrosis and/or ischemia) and left ventricular systolic wall motion and thickening abnormalities. conclusion: patients with ed have higher estimated probability of presenting segmental myocardial perfusion and functional contraction impairment and, therefore, cad, independent of the aging factor. the authors conclude that ed may be considered not only a marker for cad but also a condition related to the occurrence of major coronary events such as mi and pcta.
Superconductivity in strongly repulsive fermions: the role of kinetic-energy frustration
L. Isaev,G. Ortiz,C. D. Batista
Physics , 2010, DOI: 10.1103/PhysRevLett.105.187002
Abstract: We discuss a physical mechanism of a non-BCS nature which can stabilize a superconducting state in a {\it strongly repulsive} electronic system. By considering the two-dimensional Hubbard model with spatially modulated electron hoppings, we demonstrate how kinetic-energy frustration can lead to robust d-wave superconductivity at {\it arbitrarily} large on-site repulsion. This phenomenon should be observable in experiments using fermionic atoms, e.g. ${}^{40}K$, in specially prepared optical lattices.
DETERMINACIóN DE METABOLITOS DE INTERES FARMACOLóGICO EN PLANTAS MICROPROPAGADAS DE Larrea divaricata Cav.
L. Palacio,C.V. Lloret,C. Baeza,L. Ortiz
Boletín Latinoamericano y del Caribe de Plantas Medicinales y Aromáticas , 2007,
Abstract: Se desarrolló un protocolo eficiente para la inducción y regeneración de plantas de Larrea divaricata. La parte basal (raíz con 2 nudos) o estacas apicales (2 nudos) de plántulas obtenidas in vitro fueron sembradas en medio basal MS al que se le adicionó BA (N6-beciladenina) y ANA (ácido naftalenacético) en diferentes combinaciones concentraciones. Se observó solo capacidad de regeneración en los explantos provenientes de la parte basal cultivados en los medios control (MS) y ANA:BA a las concentraciones (mM) de 0.05:2 (A), 0.05:2.2 (B), 0.05:22 (C) y 0.5:2 (D) mM. La capacidad de enraizamiento de los ápices fue logrado en medio MS conteniendo ácido indol butírico (10 y 30 m/L AIB) con posterior recultivación en MS con sales diluidas a 1/3 y 1/2, en ausencia de reguladores de crecimiento. Los metabolitos ácido nordihidroguaiarético (ANDG) y quercetina libre fueron cuantificados mediante HPLC. Se observaron variaciones en el contenidos de ambos entre las plantas micropropagadas analizadas. La mayor concentración de ANDG se encontró en los medios MS control (10,47 mg/g de peso seco) y adicionado con ANA 0.5: BA 2 mM (7,03 mg/g de peso seco). La concentración del otro metabolito estudiado, quercetina libre, se observó en las plantas crecidas en los medios ANA/BA: 0.05:2 (0,58 mg/g de peso seco), 0.05:22 (0,23 mg/g de peso seco). Mediante el uso del cultivo in vitro se garantiza una fuente estable y uniforme de principios activos de interés farmacológicos en las plantas obtenidas bajo condiciones controladas.
On the anticonvulsant activity of kaurenic acid
Daló,Nelson L; Sosa-Sequera,Miriam C; Usubillaga,Alfredo;
Investigación Clínica , 2007,
Abstract: kaurenic acid [(-)-kaur-16-en-19-oic acid] is a diterpene isolated from the aerial parts of espeletia semiglobulata, one of 85 species of espeletiinae found in venezuela. its anticonvulsive activity was studied using two different models of experimental seizures: spinal seizures induced by sudden cooling (sssc) in amphibians and seizures induced by pentylenetetrazol (ptz) in mice. in sssc, kaurenic acid (ka) inhibited the tonic hind-limb extension with an ed50 of 2.5 mg/kg. it was 4-fold more potent than known anticonvulsant drugs such as carbamazepine and phenytoin and 100-fold more potent than valproic acid. however, ka as well as valproic acid were ineffective against the clonic phase of sssc. in the ptz-induced seizures, ka at doses of 0.625 and 1.25 mg/kg increased the latency of seizure onset and protected against generalized clonic-tonic seizures by 45% and 65%, respectively. the sedative effects of ka had an ed50 of 8.5 mg/kg in mice and 75 mg/kg in amphibians. this work provides experimental evidence supporting the potential value of kaurenic acid as an anticonvulsive drug.
On the anticonvulsant activity of kaurenic acid Sobre la actividad anticonvulsiva del ácido kaurénico
Nelson L Daló,Miriam C Sosa-Sequera,Alfredo Usubillaga
Investigación Clínica , 2007,
Abstract: Kaurenic acid [(-)-kaur-16-en-19-oic acid] is a diterpene isolated from the aerial parts of Espeletia semiglobulata, one of 85 species of Espeletiinae found in Venezuela. Its anticonvulsive activity was studied using two different models of experimental seizures: spinal seizures induced by sudden cooling (SSSC) in amphibians and seizures induced by pentylenetetrazol (PTZ) in mice. In SSSC, kaurenic acid (KA) inhibited the tonic hind-limb extension with an ED50 of 2.5 mg/kg. It was 4-fold more potent than known anticonvulsant drugs such as carbamazepine and phenytoin and 100-fold more potent than valproic acid. However, KA as well as valproic acid were ineffective against the clonic phase of SSSC. In the PTZ-induced seizures, KA at doses of 0.625 and 1.25 mg/kg increased the latency of seizure onset and protected against generalized clonic-tonic seizures by 45% and 65%, respectively. The sedative effects of KA had an ED50 of 8.5 mg/kg in mice and 75 mg/kg in amphibians. This work provides experimental evidence supporting the potential value of kaurenic acid as an anticonvulsive drug. El ácido kaurénico [(-)-kaur-16-en-19-oic acid] es un diterpeno aislado de las partes aéreas de la planta Espeletia semiglobulata, una de la 85 especies de Espeletiinae encontradas en Venezuela. El efecto anticonvulsivo del ácido kaurénico fue estudiado empleando dos modelos diferentes de convulsiones experimentales: convulsiones espinales inducidas por enfriamiento brusco (SSSC) en anfibios y convulsiones inducidas por pentilenotetrazol (PTZ) en ratones. En SSSC, el ácido kaurénico (KA) inhibió la fase tónica con una ED50 de 2,5 mg/kg. KA fue cuatro veces más potente que anticonvulsivos conocidos tales como carbamazepina y fenitoína y 100 veces más potente que el ácido valproico. Sin embargo, el KA al igual que el ácido valproico, fueron inefectivos contra la fase clónica de las SSSC. En convulsiones inducidas por PTZ en ratones, el KA aumentó la latencia y disminuyó la incidencia de la fase clónica-tónica generalizada de las convulsiones inducidas por PTZ en 45% y 65%, a dosis de 0,62 y 1,25 mg/kg, respectivamente. KA produjo sedación a una dosis efectiva (ED50) de 8,5 mg/kg en los ratones y de 75 mg/kg en anfibios. Este trabajo aporta evidencia experimental que soporta el valor potencial del KA como una droga anticonvulsiva.
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