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Showing papers by "University of Seville published in 2002"


Journal ArticleDOI
01 Mar 2002-Science
TL;DR: A method to generate steady coaxial jets of immiscible liquids with diameters in the range of micrometer/nanometer size is reported, which has produced monodisperse capsules with diameter varying between 10 and 0.15 micrometers, depending on the running parameters.
Abstract: We report a method to generate steady coaxial jets of immiscible liquids with diameters in the range of micrometer/nanometer size. This compound jet is generated by the action of electro-hydrodynamic (EHD) forces with a diameter that ranges from tens of nanometers to tens of micrometers. The eventual jet breakup results in an aerosol of monodisperse compound droplets with the outer liquid surrounding or encapsulating the inner one. Following this approach, we have produced monodisperse capsules with diameters varying between 10 and 0.15 micrometers, depending on the running parameters.

989 citations


Journal ArticleDOI
TL;DR: In this article, the existence of bianisotropic effects in those materials is investigated, making use of an approximate model, and some unexplained properties of the electromagnetic-wave propagation through these media, revealed by closer inspection of previous numerical simulations and experimental work, are highlighted.
Abstract: The recently proposed artificial media with negative magnetic permeability and left-handed metamaterials are revisited at the light of the theory of artificial bi(iso/aniso)tropic media. In particular, the existence of bianisotropic effects in those materials is investigated, making use of an approximate model. Some unexplained properties of the electromagnetic-wave propagation through these media, revealed by closer inspection of previous numerical simulations and experimental work, are highlighted. It is shown that these peculiarities are properly explained if the bianisotropy is explicitly accounted for. The bianisotropy is related to the existence of magnetoelectric coupling in the artificial constituents (artificial atoms) of the medium. A simple modification of the artificial atom that precludes the bianisotropy is also proposed.

894 citations


Journal ArticleDOI
16 May 2002-Nature
TL;DR: The data indicate that the TREX complex has a conserved role in coupling transcription to mRNA export, and is specifically recruited to activated genes during transcription and travels the entire length of the gene with RNA polymerase II.
Abstract: The essential yeast proteins Yra1 and Sub2 are messenger RNA export factors that have conserved counterparts in metazoans, designated Aly and UAP56, respectively1,2,3,4,5,6,7. These factors couple the machineries that function in splicing and export of mRNA1,2,3,4,5,6,7. Here we show that both Yra1 and Sub2 are stoichiometrically associated with the heterotetrameric THO complex8, which functions in transcription in yeast8,9,10,11. We also show that Sub2 and Yra1 interact genetically with all four components of the THO complex (Tho2, Hpr1, Mft1 and Thp2). Moreover, these components operate in the export of bulk poly(A)+ RNA as well as of mRNA derived from intronless genes. Both Aly and UAP56 associate with human counterparts of the THO complex. Together, these data define a conserved complex, designated the TREX (‘transcription/export’) complex. The TREX complex is specifically recruited to activated genes during transcription and travels the entire length of the gene with RNA polymerase II. Our data indicate that the TREX complex has a conserved role in coupling transcription to mRNA export.

811 citations


Journal ArticleDOI
TL;DR: The beneficial effects for human health of clay minerals are examined, describing their use in pharmaceutical formulations, spas and aesthetic medicine, and their applications in aesthetic medicine.

534 citations


Journal ArticleDOI
TL;DR: It will be shown that EM transmission in this structure is feasible within a certain frequency band even if the transverse dimensions of the waveguide are much smaller than the associated free-space wavelength.
Abstract: At microwave frequencies, hollow metallic waveguides behave in certain aspects as a ``one-dimensional plasma.'' This feature will be advantageously used for simulating the propagation of electromagnetic (EM) waves in left-handed metamaterials provided the hollow waveguide is periodically loaded with split ring resonators. It will be shown that EM transmission in this structure is feasible within a certain frequency band even if the transverse dimensions of the waveguide are much smaller than the associated free-space wavelength. This effect can be qualitatively and quantitatively explained by the left-handed metamaterial theory, thus providing a new experimental validation for such a theory.

528 citations


Journal ArticleDOI
TL;DR: Although there is overwhelming information demonstrating the immunoenhancing properties of melatonin, many questions related to the cytokines involved and the mechanisms of action of the indoleamine require answers.
Abstract: In this paper we review the historical milestones that first highlighted the existence of a relationship between melatonin and the immune system and we summarize data from experiments which correlate the rhythmic production of melatonin with the rhythmic activity of the immune system. The effects of pinealectomy and in vivo administration of melatonin on a variety of immune parameters, including specific and non-specific immunity are considered and we also present contradictory data concerning the effect of melatonin in cultured immunocompetent cells and a possible scheme of how melatonin regulates the production of a number of cytokines. Finally, the mechanism of action of melatonin in the immune system is discussed. Many data suggest the existence of both nuclear and membrane receptors for melatonin in the immune system. Both of these appear to be clearly identified but their specific physiological role is still under discussion. In summary, although there is overwhelming information demonstrating the immunoenhancing properties of melatonin, many questions related to the cytokines involved and the mechanisms of action of the indoleamine require answers.

446 citations


Journal ArticleDOI
TL;DR: Experimental observations of the fluid flow profile obtained by superimposing images of particle movement in a plane normal to the electrode surface are presented and good agreement is found between the numerical and experimental streamlines.
Abstract: The application of a nonuniform ac electric field to an electrolyte using coplanar microelectrodes results in steady fluid flow. The flow has its origin in the interaction of the tangential component of the nonuniform field with the induced charge in the electrical double layer on the electrode surfaces. Termed ac electro-osmosis, the flow has been studied experimentally and theoretically using linear analysis. This paper presents experimental observations of the fluid flow profile obtained by superimposing images of particle movement in a plane normal to the electrode surface. These experimental streamlines demonstrate that the fluid flow is driven at the surface of the electrodes. Experimental measurements of the impedance of the electrical double layer on the electrodes are also presented. The potential drop across the double layer at the surface of the electrodes is calculated numerically using a linear double layer model, and also using the impedance of the double layer obtained from experimental data. The ac electro-osmotic flow at the surface of the electrodes is then calculated using the Helmholtz-Smoluchowski formula. The bulk fluid flow driven by this surface velocity is numerically calculated as a function of frequency and good agreement is found between the numerical and experimental streamlines.

404 citations


Journal ArticleDOI
TL;DR: The results suggest that the nigrostriatal dopaminergic system is susceptible to damage by inflammatory events and that these may be implicated in neurodegeneration processes such as Parkinson's disease.
Abstract: The pathogenesis of Parkinson's disease is still poorly understood. To address the hypothesis that immune-mediated events, such as microglial activation, may be involved in the dopaminergic neurodegeneration, we have studied the effect that intranigral injection of the immunostimulant lipopolysaccharide has on monoaminergic neurotransmitters in rats. Activation of microglial cells, visualized by immunohistochemistry with a specific monoclonal antibody, was already obvious 2 days after injection. In relation to the biochemical parameters studied, we found a significant decrease of dopamine levels in both the substantia nigra and striatum up to at least 21 days after intranigral injection of lipopolysaccharide. This result was supported by the decrease in tyrosine hydroxylase activity and the loss of tyrosine hydroxylase-positive neuronal bodies, shown by immunohistochemistry. These alterations of the dopaminergic system did not reverse during the interval studied (21 days); conversely, the serotoninergic system suffered only transient damage. In addition, we found that the neurotoxic effect of lipopolysaccharide was not mediated by nitric oxide. Based on our results we suggest that the nigrostriatal dopaminergic system is susceptible to damage by inflammatory events and that these may be implicated in neurodegeneration processes such as Parkinson's disease.

380 citations


Journal ArticleDOI
TL;DR: An integrative view is provided on how transcription can control different aspects of genomic integrity, by exploring different mechanisms that might be responsible for transcription‐associated mutation (TAM) and transcription‐ associated recombination (TAR).
Abstract: Transcription is a central aspect of DNA metabolism that takes place on the same substrate as replication, repair and recombination. Not surprisingly, therefore, there is a physical and functional connection between these processes. In recent years, transcription has proven to be a relevant player in the maintenance of genome integrity and in the induction of genetic instability and diversity. The aim of this review is to provide an integrative view on how transcription can control different aspects of genomic integrity, by exploring different mechanisms that might be responsible for transcription-associated mutation (TAM) and transcription-associated recombination (TAR).

331 citations


Journal ArticleDOI
TL;DR: The antioxidant capacity of saliva could constitute a first line of defence against free radical-mediated oxidative stress, since the process of mastication and digestion of ingested foods promotes a variety of reactions, including lipid peroxidation.
Abstract: Background/aims: Saliva, a heterogeneous fluid comprising proteins, glycoproteins, electrolytes, small organic molecules and compounds transported from the blood, constantly bathes the teeth and oral mucosa. It acts as a cleansing solution, an ion reservoir, a lubricant and a buffer. In addition to its other host-protective properties, saliva could constitute a first line of defence against free radical-mediated oxidative stress, since the process of mastication and digestion of ingested foods promotes a variety of reactions, including lipid peroxidation. Moreover, during gingival inflammation, gingival crevicular fluid flow increases the change of saliva composition with products from the inflammatory response; this, in turn, could have some role in controlling and/or modulating oxidative damages in the oral cavity. This is the reason why the antioxidant capacity of saliva has led to increasing interest, and the development of techniques suitable for saliva antioxidant evaluation.Materials and Methods: Here, we review the current peer-reviewed literature concerning the nature and characteristics of free radicals, reactive oxygen species, oxidants, pro-oxidants and antioxidants in saliva, especially pro-oxidant and antioxidant features, as well as current methods for assessing the antioxidant capacity of saliva.Results and Conclusions: In the last decade, several methods have been developed for assaying the antioxidant activity of saliva, indicating an increasing interest of researchers and clinicians. Unfortunately, systematic studies of saliva are still lacking, even in healthy populations.

319 citations


Journal ArticleDOI
TL;DR: A sequential extraction scheme according to the BCR's guidelines was applied to sludge samples collected from each sludge treatment step of five municipal activated sludge plants, and results showed a clear rise along thesludge treatment in the proportion of two less-available fractions.

Journal ArticleDOI
TL;DR: The results indicate that lesions to the MC of turtles and to the LP of goldfish, like hippocampal lesions in mammals and birds, selectively impair map-like memory representations of the environmental space and suggest that the presence of a hippocampus-dependent spatial memory system is a primitive feature of the vertebrate forebrain that has been conserved through evolution.
Abstract: The hippocampus of mammals and birds is critical for spatial memory. Neuroanatomical evidence indicates that the medial cortex (MC) of reptiles and the lateral pallium (LP) of ray-finned fishes could be homologous to the hippocampus of mammals and birds. In this work, we studied the effects of lesions to the MC of turtles and to the LP of goldfish in spatial memory. Lesioned animals were trained in place, and cue maze tasks and crucial probe and transfer tests were performed. In experiment 1, MC-lesioned turtles in the place task failed to locate the goal during trials in which new start positions were used, whereas sham animals navigated directly to the goal independently of start location. In contrast, no deficit was observed in cue learning. In experiment 2, LP lesion produced a dramatic impairment in goldfish trained in the place task, whereas medial and dorsal pallium lesions did not decrease accuracy. In addition, none of these pallial lesions produced deficits in cue learning. These results indicate that lesions to the MC of turtles and to the LP of goldfish, like hippocampal lesions in mammals and birds, selectively impair map-like memory representations of the environmental space. Thus, the forebrain structures of reptiles and teleost fish neuroanatomically equivalent to the mammalian and avian hippocampus also share a central role in spatial cognition. Present results suggest that the presence of a hippocampus-dependent spatial memory system is a primitive feature of the vertebrate forebrain that has been conserved through evolution.

Proceedings ArticleDOI
07 Aug 2002
TL;DR: In this article, a new basic cell for low power and/or lowvoltage operation is identified, which is called flipped voltage follower (FVF) and it is shown that different versions of this cell, called FVF, have been used in the past for different applications.
Abstract: In this paper a new basic cell for low-power and/or low-voltage operation is identified. It is shown that different versions of this cell, called "flipped voltage follower", have been used in the past for different applications. New circuits using this cell are also proposed here.

Journal ArticleDOI
TL;DR: A functional link between the processes of elongation and metabolism of nascent mRNA mediated by THO and mRNA export proteins, which have important consequences for the maintenance of genome stability are indicated.
Abstract: The THO complex is a multimeric factor containing four polypeptides, Tho2, Hpr1, Mft1 and Thp2. Mutations in any of the genes encoding THO confer impairment of transcription and a transcription-dependent hyper-recombination phenotype, suggesting that THO has a functional role in gene expression. Using an in vivo assay developed to study expression of long and G+C-rich DNA sequences, we have isolated SUB2, a gene involved in mRNA splicing and export, as a multicopy suppressor of the gene expression defect of hpr1Δ. Further investigation of a putative functional relationship between mRNA metabolism and THO revealed that mRNA export mutants sub2, yra1, mex67 and mtr2 have similar defective transcription and hyper-recombination phenotypes as THO mutants. In addition, THO becomes essential in cells with a defective Mex67 mRNA export er. Finally, we have shown that THO has the ability to associate with RNA and DNA in vitro. These results indicate a functional link between the processes of elongation and metabolism of nascent mRNA mediated by THO and mRNA export proteins, which have important consequences for the maintenance of genome stability.

Journal ArticleDOI
TL;DR: The ability to release the active substance was examined as a function of some technological parameters and pH of dissolution medium and the nature of the gelifying cation allow a control of the release rate of the drug.

Journal ArticleDOI
TL;DR: This review attempts to compile and discuss the literature studying structure-activity relationships, in order to show structural requirements implicated in the anticancer activity of flavonoids, which might help to rationalize their development as antitumor agents.
Abstract: The protection against some forms of cancer provided by many common foods has been observed in multiple epidemiological studies. Non-nutritive dietary compounds, such as flavonoids, have been considered as the responsible agents for such observations and since then, much research activity has been done about their potential anticancer effect. As a result, these compounds have been shown to regulate proliferation and cell death pathways leading to cancer. Thus, flavonoids such as the synthetic flavone, flavopiridol; the soy isoflavonoid, genistein; the tea catechin epigallocatechin gallate; or the common dietary flavonol, quercetin, are emerging as prospective anticancer drug candidates and some of them have already entered in clinical trials. In view of the therapeutic potential of flavonoids, many researchers have tried to elucidate possible structure-activity relationships that might lead to new drug discovery. However, and possibly due to the information being very scattered, there is very little understanding about a possible relationship between the flavonoid structure and their anticancer activity. Besides their therapeutic potential, since lots of flavonoids are present in our diet, a greater understanding of their anticancer properties might also modify our dietary habits in order to attack cancer with an effective weapon, prevention. This paper seeks to show, in a brief but comprehensive way, the anticancer properties of flavonoids. Through an understanding of the cancer process and its treatment, flavonoids are studied as possible useful compounds in cancer prevention and cancer therapy. Furthermore, this review attempts to compile and discuss the literature studying structure-activity relationships, in order to show structural requirements implicated in the anticancer activity of flavonoids, which might help to rationalize their development as antitumor agents.

Journal ArticleDOI
TL;DR: These functional data support the homology between the medial pallium of the teleost and the pallial amygdala of land vertebrates, and between theteleost lateral pallium and the mammalian hippocampus.

Journal ArticleDOI
TL;DR: Results suggest that inflammatory response is implicated in LPS‐induced neurodegeneration, and may be due, at least in part, to a cascade of events independent of that described for TNF‐α/IL‐1β/IFN‐γ.
Abstract: It is becoming widely accepted that the inflammatory response is involved in neurodegenerative disease. In this context, we have developed an animal model of dopaminergic system degeneration by the intranigral injection of lipopolysaccharide (LPS), a potent inductor of inflammation. To address the importance of the inflammatory response in the LPS-induced degeneration of nigral dopaminergic neurones, we carried out two different kinds of studies: (i) the possible protective effect of an anti-inflammatory compound, and (ii) the effect of the intranigral injection of inflammatory cytokines (TNF-α, IL-1β and IFN-γ) on dopaminergic neurones viability. Present results show that dexamethasone, a potent anti-inflammatory drug that interferes with many of the features characterizing pro-inflammatory glial activation, prevented the loss of catecholamine content, Tyrosine hydroxylase (TH) activity and TH immunostaining induced by LPS-injection and also the bulk activation of microglia/macrophages. Surprisingly, injection of the pro-inflammatory cytokines failed to reproduce the LPS effect. Taken together, our results suggest that inflammatory response is implicated in LPS-induced neurodegeneration. This damage may be due, at least in part, to a cascade of events independent of that described for TNF-α/IL-1β/IFN-γ.

Journal ArticleDOI
TL;DR: In this article, a priori estimates for the Calderon-zygmund kernel are proved for multilinear commutators with vector symbol defined by a constant such that the operators satisfy corresponding weighted-type estimates with.
Abstract: Multilinear commutators with vector symbol defined by \[ T_{\vec{b}}(f)(x)=\int_{{\bb R}^n}\Bigg[\prod\limits^m_{j=1}(b_j(x)-b_j(y))\Bigg]K(x,y)f(y)dy \] are considered, where is a Calderon–Zygmund kernel. The following a priori estimates are proved for . For , there exists a constant such that \[ \|\dot{T}_{{\vec{b}}}(f)\|_{L^P(w)}\le C\|\vec{b}\|\|M_{L(\log\,L)^{1/r}}(f)\|_{L^P(w)} \] and \[ \sup_{t>0}\frac{1}{\Phi(\frac{1}{t})}w(\{y\in{\bb R}^n:|T_{\vec{b}}f(y)|>t\})\le C\sup_{t>0}\frac{1}{\Phi(\frac{1}{t})}w(\{y\in{\bb R}^n:M_{L(\log\,L)^{1/r}}(\|\vec{b}\|f)(y)>t\}), \] where \begin{eqnarray*} &\|\vec{b}\|=\prod\limits^m_{j=1}\|b_j\|_{osc_{\exp L}^r j},\\ &\Phi(t)=t\log^{1/r}(e+t),\quad \frac{1}{r}=\frac{1}{r_1}+\cdots+\frac{1}{r_m}, \end{eqnarray*} and is an Orlicz type maximal operator. This extends, with a different approach, classical results by Coifman.As a corollary, it is deduced that the operators are bounded on when , and that they satisfy corresponding weighted -type estimates with .

Journal ArticleDOI
TL;DR: Data presented suggest that early in vertebrate evolution, the medial pallium of an ancestral fish group that gave rise to the extant vertebrates became specialized for processing and encoding complex spatial information, and that this functional trait has been retained through the evolution of each independent vertebrate lineage.

Journal ArticleDOI
TL;DR: In this paper, the chemical speciation of 11 metals in aerosols has been studied in 12 areas of the city of Seville (Spain) using a high-volume sampling system equipped with a cascade impactor, which effectively separates the particulate matter into six size ranges.

Journal ArticleDOI
TL;DR: The results of this work suggest that the melt granulation technique is an easy and fast method to improve the dissolution rate of ibuprofen, using poloxamer 188 as a new hydrophilic meltable binder.

Journal ArticleDOI
TL;DR: In this paper, the physicochemical parameters of 98 samples of Moroccan honeys were analysed; nine parameters were measured, including water content, pH, acidity (free, lactonic, total and lactonic acidity/free acidity ratio), hydroxymethylfurfural, diastase activity and proline.

Journal ArticleDOI
TL;DR: The use of submerged bacterial culture and a continuous aeration system has been used to produce wine vinegar in most Mediterranean countries and extensively used as a condiment, acidifying and food preserving agent as discussed by the authors.
Abstract: Wine vinegar is produced in most Mediterranean countries and extensively used as a condiment, acidifying and food preserving agent. Traditional production requires maturation in wood for many years to obtain a high acetic degree and the resulting product is relatively expensive. New technologies are being designed to overcome this difficulty with the objective of producing vinegars with a similar quality and at the same time less expensive. These methods of production involve the use of submerged bacterial culture and a continuous aeration system. Recent research is focussed in improving yield and quality of the final product.

Journal ArticleDOI
TL;DR: It is shown that low glucose increases secretion from glomus cells in the carotid bodies, sensory organs whose stimulation by hypoxia produces sympathetic activation, by a process that depends on extracellular Ca2+ influx and is paralleled by inhibition of voltage-gated K+ channels.
Abstract: Decreased plasma glucose concentration elicits a complex neuroendocrine response that prevents or rapidly corrects hypoglycemia as required to preserve brain function1,2,3,4; however, where and how low glucose is sensed is unknown4,5,6. Here we show that low glucose increases secretion from glomus cells in the carotid bodies, sensory organs whose stimulation by hypoxia produces sympathetic activation, by a process that depends on extracellular Ca2+ influx and is paralleled by inhibition of voltage-gated K+ channels. We propose a new glucose-sensing role for the carotid body glomus cell that serves to integrate information about blood glucose and O2 levels and to activate counterregulatory responses.

Journal ArticleDOI
TL;DR: In this article, a proof of Bell's theorem without inequalities valid for both inequivalent classes of three-qubit entangled states under local operations assisted by classical communication, namely Greenberger-Horne-Zeilinger (GHZ) and $W,$ is described.
Abstract: A proof of Bell's theorem without inequalities valid for both inequivalent classes of three-qubit entangled states under local operations assisted by classical communication, namely Greenberger-Horne-Zeilinger (GHZ) and $W,$ is described. This proof leads to a Bell inequality that allows more conclusive tests of Bell's theorem for three-qubit systems. Another Bell inequality involving both tri- and bipartite correlations is introduced which illustrates the different violations of local realism exhibited by the GHZ and $W$ states.

Journal ArticleDOI
01 Oct 2002-Fuel
TL;DR: In this article, the intrinsic gasification reactivity of pressed oil-stone char gasification rates were measured in a thermogravimetric apparatus to assess the importance of diffusion limitations.

Journal ArticleDOI
TL;DR: It is proposed that the oncogenic effect of increased expression of securin may result from modulation of p53 functions, and the physiological relevance of this interaction in PTTG1-deficient human tumor cells (PTTG1−/−).
Abstract: Human securin interacts with p53 and modulates p53-mediated transcriptional activity and apoptosis

Journal ArticleDOI
TL;DR: Based on the chemical distribution of metals, it is found that Cd, Zn and Cu are the most mobile metals (i.e., metals that can pass easily into the water under changing environmental conditions).

Journal ArticleDOI
TL;DR: In this article, a power law relationship between grain size and toughness increment was found for nanocrystalline tetragonal zirconia ceramics, and a linear relationship between yttria content and inverse critical grain size was found.