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Find video protocols related to scientific articles indexed in Pubmed.
Influence of high hydrostatic pressure on quality parameters and structural properties of aloe vera gel (Aloe barbadensis Miller).
J Food Sci Technol
PUBLISHED: 10-21-2014
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The aim of this work was to study the effect of high hydrostatic pressure (HHP) on colour, dietary fibre, vitamin C content, polysaccharides content, physico-chemical and structural properties of aloe vera gel at three pressure levels (300, 400 and 500 MPa for 3 min) after 35 days of storage at 4?±?1 °C. The results showed that HHP exerted a clear influence on most of the quality parameters studied. Moisture, protein and fat contents did not show changes with an increasing pressure. Ash, crude fibre and carbohydrates content increased with increasing pressure. Vitamin C content did not show significant differences after 35 days of storage. The variation of colour in the samples increased at 500 MPa. Total dietary fibre, water holding capacity and firmness increased with pressure. However, all HHP-treated samples presented a decrease in hydration ratio and polysaccharides content; and also minor alterations in the structural properties were produced at HHP of 300-500 MPa, resulting in a high quality gel.
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Prediction of compound potency changes in matched molecular pairs using support vector regression.
J Chem Inf Model
PUBLISHED: 09-17-2014
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Matched molecular pairs (MMPs) consist of pairs of compounds that are transformed into each other by a substructure exchange. If MMPs are formed by compounds sharing the same biological activity, they encode a potency change. If the potency difference between MMP compounds is very small, the substructure exchange (chemical transformation) encodes a bioisosteric replacement; if the difference is very large, the transformation encodes an activity cliff. For a given compound activity class, MMPs comprehensively capture existing structural relationships and represent a spectrum of potency changes for structurally analogous compounds. We have aimed to predict potency changes encoded by MMPs. This prediction task principally differs from conventional quantitative structure-activity relationship (QSAR) analysis. For the prediction of MMP-associated potency changes, we introduce direction-dependent MMPs and combine MMP analysis with support vector regression (SVR) modeling. Combinations of newly designed kernel functions and fingerprint descriptors are explored. The resulting SVR models yield accurate predictions of MMP-encoded potency changes for many different data sets. Shared key structure context is found to contribute critically to prediction accuracy. SVR models reach higher performance than random forest (RF) and MMP-based averaging calculations carried out as controls. A comparison of SVR with kernel ridge regression indicates that prediction accuracy has largely been a consequence of kernel characteristics rather than SVR optimization details.
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Involvement of autophagy in melatonin-induced cytotoxicity in glioma-initiating cells.
J. Pineal Res.
PUBLISHED: 09-09-2014
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Glioblastoma-initiating cells (GICs) represent a stem cell-like subpopulation within malignant glioblastomas responsible for tumor development, progression, therapeutic resistance, and tumor relapse. Thus, eradication of this subpopulation is essential to achieve stable, long-lasting remission. We have previously reported that melatonin decreases cell proliferation of glioblastoma cells both in vitro and in vivo and synergistically increases effectiveness of drugs in glioblastoma cells and also in GICs. In this study, we evaluated the effect of the indolamine alone in GICs and found that melatonin treatment reduces GICs proliferation and induces a decrease in self-renewal and clonogenic ability accompanied by a reduction in the expression of stem cell markers. Moreover, our results also indicate that melatonin treatment, by modulating stem cell properties, induces cell death with ultrastructural features of autophagy. Thus, data reported here reinforce the therapeutic potential of melatonin as a treatment of malignant glioblastoma both by inhibiting tumor bulk proliferation or killing GICs, and simultaneously enhancing the effect of chemotherapy.
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Discovery of 1-butyl-3-chloro-4-(4-phenyl-1-piperidinyl)-(1H)-pyridone (JNJ-40411813): a novel positive allosteric modulator of the metabotropic glutamate 2 receptor.
J. Med. Chem.
PUBLISHED: 07-28-2014
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We previously reported the discovery of 4-aryl-substituted pyridones with mGlu2 PAM activity starting from the HTS hit 5. In this article, we describe a different exploration from 5 that led to the discovery of a novel subseries of phenylpiperidine-substituted pyridones. The optimization strategy involved the introduction of different spacers between the pyridone core and the phenyl ring of 5. The fine tuning of metabolism and hERG followed by differentiation of advanced leads that were identified on the basis of PK profiles and in vivo potency converged on lead compound 36 (JNJ-40411813). Full in vitro and in vivo profiles indicate that 36 displayed an optimal interplay between potency, selectivity, favorable ADMET/PK and cardiovascular safety profile, and central EEG activity. Compound 36 has been investigated in the clinic for schizophrenia and anxious depression disorders.
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Surgical adverse events of deep brain stimulation in the subthalamic nucleus of patients with Parkinson's disease. The learning curve and the pitfalls.
Acta Neurochir (Wien)
PUBLISHED: 03-25-2014
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Several surgical adverse events (SAEs) have been associated with Deep Brain Stimulation (DBS) of the subthalamic nucleus (STN) in Parkinson's Disease (PD) patients, leading to certain confusion about the risk/benefit ratio of this technique, and giving rise to the need of more and more extensive control studies over longer periods. The aim of this article is to identify and quantify the factors associated with the most frequent AEs from STN DBS in PD-diagnosed patients.
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Atmospheric reactions of methylcyclohexanes with Cl atoms and OH radicals: determination of rate coefficients and degradation products.
Environ Sci Pollut Res Int
PUBLISHED: 01-30-2014
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As the result of biogenic and anthropogenic activities, large quantities of chemical compounds are emitted into the troposphere. Alkanes, in general, and cycloalkanes are an important chemical class of hydrocarbons found in diesel, jet and gasoline, vehicle exhaust emissions, and ambient air in urban areas. In general, the primary atmospheric fate of organic compounds in the gas phase is the reaction with hydroxyl radicals (OH). The oxidation by Cl atoms has gained importance in the study of atmospheric reactions because they may exert some influence in the boundary layer, particularly in marine and coastal environments, and in the Arctic troposphere. The aim of this paper is to study of the atmospheric reactivity of methylcylohexanes with Cl atoms and OH radicals under atmospheric conditions (in air at room temperature and pressure). Relative kinetic techniques have been used to determine the rate coefficients for the reaction of Cl atoms and OH radicals with methylcyclohexane, cis-1,4-dimethylcyclohexane, trans-1,4-dimethylcyclohexane, and 1,3,5-trimethylcyclohexane at 298?±?2 K and 720?±?5 Torr of air by Fourier transform infrared) spectroscopy and gas chromatography-mass spectrometry (GC-MS) in two atmospheric simulation chambers. The products formed in the reaction under atmospheric conditions were investigated using a 200-L Teflon bag and employing the technique of solid-phase microextraction coupled to a GC-MS. The rate coefficients obtained for the reaction of Cl atoms with the studied compounds are the following ones (in units of 10(-10) cm(3) molecule(-1) s(-1)): (3.11?±?0.16), (2.89?±?0.16), (2.89?±?0.26), and (2.61?±?0.42), respectively. For the reactions with OH radicals the determined rate coefficients are (in units of 10(-11) cm(3) molecule(-1) s(-1)): (1.18?±?0.12), (1.49?±?0.16), (1.41?±?0.15), and (1.77?±?0.23), respectively. The reported error is twice the standard deviation. A detailed mechanism for ring-retaining product channels is proposed to justify the observed reaction products. The global tropospheric lifetimes estimated from the reported OH- and Cl-rate coefficients show that the main removal path for the investigated methylcyclohexanes is the reaction with OH radicals. But in marine environments, after sunrise, Cl reactions become more important in the tropospheric degradation. Thus, the estimated lifetimes range from 16 to 24 h for the reactions of the OH radical (calculated with [OH]?=?10(6) atoms cm(-3)) and around 7-8 h in the reactions with Cl atoms in marine environments (calculated with [Cl]?=?1.3?×?10(5) atoms cm(-3)). The reaction of Cl atoms and OH radicals and methylcylohexanes can proceed by H abstraction from the different positions.
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Noise estimation in parallel MRI: GRAPPA and SENSE.
Magn Reson Imaging
PUBLISHED: 01-15-2014
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Parallel imaging methods allow to increase the acquisition rate via subsampled acquisitions of the k-space. SENSE and GRAPPA are the most popular reconstruction methods proposed in order to suppress the artifacts created by this subsampling. The reconstruction process carried out by both methods yields to a variance of noise value which is dependent on the position within the final image. Hence, the traditional noise estimation methods - based on a single noise level for the whole image - fail. In this paper we propose a novel methodology to estimate the spatial dependent pattern of the variance of noise in SENSE and GRAPPA reconstructed images. In both cases, some additional information must be known beforehand: the sensitivity maps of each receiver coil in the SENSE case and the reconstruction coefficients for GRAPPA.
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Formation of activity cliffs is accompanied by systematic increases in ligand efficiency from lowly to highly potent compounds.
AAPS J
PUBLISHED: 01-09-2014
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Activity cliffs (ACs) are defined as pairs of structurally similar compounds sharing the same biological activity but having a large difference in potency. Therefore, ACs are often studied to rationalize structure-activity relationships (SARs) and aid in lead optimization. Hence, the AC concept plays an important role in compound development. For compound optimization, ligand efficiency (LE) represents another key concept. LE accounts for the relation between compound potency and mass. A major goal of lead optimization is to increase potency and also LE. Despite their high relevance for drug development, the AC and LE concepts have thus far not been considered in combination. It is currently unknown how compounds forming ACs might be related in terms of LE. To explore this question, ACs were systematically identified on the basis of high-confidence activity data and LE values for cliff partners were determined. Surprisingly, a significant increase in LE was generally detected for highly potent cliff partners compared to their lowly potent counterparts, regardless of the compound classes and their targets. Hence, ACs reveal chemical modifications that determine SARs and improve LE. These findings further increase the attractiveness of AC information for compound optimization and development.
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Advancing the activity cliff concept, part II.
F1000Res
PUBLISHED: 01-01-2014
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We present a follow up contribution to further complement a previous commentary on the activity cliff concept and recent advances in activity cliff research. Activity cliffs have originally been defined as pairs of structurally similar compounds that display a large difference in potency against a given target. For medicinal chemistry, activity cliffs are of high interest because structure-activity relationship (SAR) determinants can often be deduced from them. Herein, we present up-to-date results of systematic analyses of the ligand efficiency and lipophilic efficiency relationships between activity cliff-forming compounds, which further increase their attractiveness for the practice of medicinal chemistry. In addition, we summarize the results of a new analysis of coordinated activity cliffs and clusters they form. Taken together, these findings considerably add to our evaluation and current understanding of the activity cliff concept. The results should be viewed in light of the previous commentary article.
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Immunotherapy reduces allergen-mediated CD66b expression and myeloperoxidase levels on human neutrophils from allergic patients.
PLoS ONE
PUBLISHED: 01-01-2014
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CD66b is a member of the carcinoembryonic antigen family, which mediates the adhesion between neutrophils and to endothelial cells. Allergen-specific immunotherapy is widely used to treat allergic diseases, and the molecular mechanisms underlying this therapy are poorly understood. The present work was undertaken to analyze A) the in vitro effect of allergens and immunotherapy on cell-surface CD66b expression of neutrophils from patients with allergic asthma and rhinitis and B) the in vivo effect of immunotherapy on cell-surface CD66b expression of neutrophils from nasal lavage fluid during the spring season. Myeloperoxidase expression and activity was also analyzed in nasal lavage fluid as a general marker of neutrophil activation. Results: CD66b cell-surface expression is upregulated in vitro in response to allergens, and significantly reduced by immunotherapy (p<0.001). Myeloperoxidase activity in nasal lavage fluid was also significantly reduced by immunotherapy, as were the neutrophil cell-surface expression of CD66b and myeloperoxidase (p<0.001). Interestingly, CD66b expression was higher in neutrophils from nasal lavage fluid than those from peripheral blood, and immunotherapy reduced the number of CD66+MPO+ cells in nasal lavage fluid. Thus, immunotherapy positive effects might, at least in part, be mediated by the negative regulation of the CD66b and myeloperoxidase activity in human neutrophils.
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Matched molecular pair-based data sets for computer-aided medicinal chemistry.
F1000Res
PUBLISHED: 01-01-2014
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Matched molecular pairs (MMPs) are widely used in medicinal chemistry to study changes in compound properties including biological activity, which are associated with well-defined structural modifications. Herein we describe up-to-date versions of three MMP-based data sets that have originated from in-house research projects. These data sets include activity cliffs, structure-activity relationship (SAR) transfer series, and second generation MMPs based upon retrosynthetic rules. The data sets have in common that they have been derived from compounds included in the latest release of the ChEMBL database for which high-confidence activity data are available. Thus, the activity data associated with MMP-based activity cliffs, SAR transfer series, and retrosynthetic MMPs cover the entire spectrum of current pharmaceutical targets. Our data sets are made freely available to the scientific community.
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Anisotropic diffusion filtering for correlated multiple-coil MRI.
Conf Proc IEEE Eng Med Biol Soc
PUBLISHED: 10-11-2013
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Recently, some methods have been proposed for filtering multi-coil MRI acquisitions with correlation between coils. Those methods are based on statistical models of noise to develop a Linear Minimum Mean Square Error (LMMSE) filter. The advantage of LMMSE-based filters stems from their simplicity and robustness. However, they exhibit some drawbacks: their performance strongly depends on the underlying statistical model and on the way the local moments are estimated. The first problem can be avoided when considering effective values provided by recent studies on the models of noise in multi-coil systems with correlation between coils. However, the local moments are estimated in square neighborhoods which can include different kinds of tissues. Thus, the local variance is biased towards upper values, which results in an inaccurate estimate in regions close to tissue boundaries. In this work we propose to overcome this problem by introducing an anisotropic diffusion step in the LMMSE estimate for correlated multi-coil systems which improves the estimation of the signal in regions where other LMMSE methods fail. Results demonstrate the better behavior in different noisy scenarios.
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Noise estimation in magnetic resonance SENSE reconstructed data.
Conf Proc IEEE Eng Med Biol Soc
PUBLISHED: 10-11-2013
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Parallel imaging methods allow to increase the acquisition rate via subsampled acquisitions of the k-space. SENSE is one of the most popular reconstruction methods proposed in order to suppress the artifacts created by this subsampling. However, the SENSE reconstruction process yields to a variance of noise value which is dependent on the position within the image. Hence, the traditional noise estimation methods based on a single noise level for the whole image fail. Accordingly, we propose a novel method to recover the complete spatial pattern of the variance of noise in SENSE reconstructed images up from the sensitivity maps of each receiver coil. Our method fits applications in statistical image processing tasks such as image denoising.
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Merging squared-magnitude approaches to DWI denoising: An adaptive Wiener filter tuned to the anatomical contents of the image.
Conf Proc IEEE Eng Med Biol Soc
PUBLISHED: 10-11-2013
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We present a new method for denoising of Diffusion Weighted Images (DWI) that shares several desirable features of state-of-the-art proposals: 1) it works with the squared-magnitude signal, allowing for a closed-form formulation as a Linear Minimum Mean Squared Error (LMMSE) estimator, a.k.a. Wiener filter; 2) it jointly accounts for the DWI channels altogether, being able to unveil anatomical structures that remain hidden in each separated channel; 3) it uses a Non-Local Means (NLM)-like scheme to discriminate voxels corresponding to different fiber bundles, being able to enhance the anatomical structures of the DWI. We report extensive experiments evidencing the new approach outperforms several related methods for all the range of input signal-to-noise ratios (SNR). An open-source C++ implementation of the algorithm is also provided for the sake of reproducibility.
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Allergen immunotherapy decreases LPS-induced NF-?B activation in neutrophils from allergic patients.
Pediatr Allergy Immunol
PUBLISHED: 09-05-2013
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Allergen-specific immunotherapy (IT) is widely used to treat allergic diseases. The molecular mechanisms have not been clarified yet completely. The present work was undertaken to analyze the effect of IT in the activation of NF-?B.
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Compound optimization through data set-dependent chemical transformations.
J Chem Inf Model
PUBLISHED: 05-20-2013
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We have searched for chemical transformations that improve drug development-relevant properties within a given class of active compounds, regardless of the compounds they are applied to. For different compound data sets, varying numbers of frequently occurring data set-dependent transformations were identified that consistently induced favorable changes of selected molecular properties. Sequences of compound pairs representing such transformations were determined that formed pathways leading from unfavorable to favorable regions of property space. Data set-dependent transformations were then applied to predict a series of compounds with increasingly favorable property values. By database searching the desired biological activity was detected for several designed molecules or compounds that were very similar to these molecules. Taken together our findings indicate that data set-dependent transformations can be applied to predict compounds that map to favorable regions of molecular property space and retain their biological activity.
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Draft Genome Sequence of the Steroid Degrader Rhodococcus ruber Strain Chol-4.
Genome Announc
PUBLISHED: 05-18-2013
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The whole-genome shotgun sequence of Rhodococcus ruber strain Chol-4 is presented here. This organism was shown to be able to grow using many steroids as the sole carbon and energy sources. These sequence data will help us to further explore the metabolic abilities of this versatile degrader.
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Net transfer of nutrients to the duodenum and disappearance of n-alkanes in the reticulo-rumen and the hindgut of sheep fed grass/legume combinations.
Br. J. Nutr.
PUBLISHED: 05-14-2013
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An experiment was carried out to examine the effect of increasing the proportion of Wimmera ryegrass hay in a lucerne hay-based diet on net transfer of nutrients to the intestine, and on the disappearance of n-alkanes in the reticulo-rumen and the hindgut of sheep. Following a latin square design, four adult ewes were fed 1:0, 0·33:0·67, 0·67:0·33 and 0:1 proportions of legume and grass. Increasing the proportion of ryegrass in the diet linearly decreased the intake of DM (P= 0·017), organic matter (P= 0·021) and N (P= 0·001). However, neutral-detergent fibre intake was not affected (P= 0·148), nor was its digestibility coefficient (P>0·10). Diet had no effect on duodenal flows of nutrients (P>0·10), although the proportion of N intake (NI) recovered at the duodenum as non-NH? N (NAN) increased linearly with Lolium rigidum in the diet (P= 0·002). Full recovery of NI as NAN was achieved at NH? concentrations in the rumen below 110 g/l. Microbial N contribution to NAN varied in a quadratic manner (P< 0·05) with the proportion of grass in the diet, although efficiency of microbial synthesis was not affected (P>0·10). Duodenal recovery of consumed n-alkanes was not affected by diet and was complete for those present in higher concentrations in the forages. Isolated rumen bacteria contained significant amounts of n-alkanes, contributing to the duodenal flow of these hydrocarbons in variable proportions depending on the diet consumed.
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[Innervation of the intervertebral disc].
Neurocirugia (Astur)
PUBLISHED: 04-10-2013
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Until very recently, intervertebral disc innervation was a subject of considerable debate. Nowadays, the introduction of inmunohistochemical techniques associated to specific antibodies and studies with retrograde tracers in nerves have allowed greater understanding of disc innervation in physiological and pathological conditions and also endings characteristics and their patterns of distribution in both situations. The existing controversies regarding structural basis of discogenic pain, have raised the interest of knowing the influence of innervation in back pain from discal origin and its characteristics. Today, we know that pathologic neoinnervation accompanying radial fissures is an important factor in the genesis of discogenic pain; within a complex mechanism in which other neurobiomechemical, inflammatory and biomechanical factors are involved.
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Histamine production by human neutrophils.
FASEB J.
PUBLISHED: 04-09-2013
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Histamine is an important mediator in the development of allergic reactions. Only a small subset of human cell types is able to produce histamine. No previous studies have shown that human neutrophils are among them. The present work was undertaken to analyze whether human neutrophils produce histamine, and to determine what agonists are involved in histamine production by human neutrophils. The expression of histidine decarboxylase in human neutrophils was established by quantitative PCR, Western blotting, and flow cytometry analysis. The activity of the enzyme was determined by ELISA, which measured histamine in the culture supernatant of neutrophils stimulated with a set of classical agonists. Human neutrophils are bona fide histamine-producing cells. Neutrophils store ?0.29 pg/cell and release ?50% of the histamine content in an antigen-dependent manner and on stimulation with other neutrophil agonists. Basal expression of histidine decarboxylase, the rate-limiting enzyme in histamine production, is higher in neutrophils from patients with allergies than from healthy donors. Our results cannot be ascribed to cell contamination for several reasons. LPS failed to induce histamine release by basophils, whereas it induced histamine release by neutrophils; and we did not detect basophils, monocytes, or lymphocytes in our neutrophil preparations. Eosinophils, albeit detected, were only 0.001-0.004% of the final cell population, and they did not store or release histamine on antigen or LPS stimulation. Antigens to which patients with allergies were sensitized stimulated release of histamine from neutrophils. These observations represent a novel view of neutrophils as possible source of histamine in the allergic diseases.
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Noise correction for HARDI and HYDI data obtained with multi-channel coils and sum of squares reconstruction: an anisotropic extension of the LMMSE.
Magn Reson Imaging
PUBLISHED: 04-03-2013
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Parallel magnetic resonance imaging (MRI) yields noisy magnitude data, described in most cases as following a noncentral ? distribution when the signals received by the coils are combined as the sum of their squares. One well-known case of this noncentral ? noise model is the Rician model, but it is only valid in the case of single-channel acquisition. Although the use of parallel MRI is increasingly common, most of the correction methods still perform Rician noise removal, yielding an erroneous result due to an incorrect noise model. Moreover, the existence of noise correlations in phased array systems renders noise nonstationary and further modifies the noise description in parallel MRI. However, the noncentral ? model has been demonstrated to work as a good approximation as long as effective voxelwise parameters are used. A good correction step, adapted to the right noise model, is of paramount importance, especially when working with diffusion-weighted MR data, whose signal-to-noise ratio is low. In this paper, we present a noise removal technique designed to be fast enough for integration into a real-time reconstruction system, thus offering the convenience of obtaining corrected data almost instantaneously during the MRI scan. Our method employs the noncentral ? noise model and uses a simplified method to account for noise correlations; this leads to an efficient and rapid correction. The method consists of an anisotropic extension of the Linear Minimum Mean Square Error estimator (LMMSE) that is a far better edge-preserving method than the traditional LMMSE and addresses noncentral ? distributions along with empirically computed global effective parameters. The results on simulated and real data demonstrate that this anisotropic extended LMMSE outperforms the original LMMSE on images corrupted by noncentral ? noise. Moreover, in comparison with the existing LMMSE technique incorporating the estimation of voxelwise effective parameters, our method yields improved results.
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Influence of process temperature on drying kinetics, physicochemical properties and antioxidant capacity of the olive-waste cake.
Food Chem
PUBLISHED: 03-23-2013
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The objective of this study was to determine the effect of drying temperature on the drying kinetics, proximal analysis, energy consumption and the antioxidant capacity of the olive-waste cake "Picual" variety from 40 to 90°C. Evaluation of proximal analysis evidenced the influence of temperature on the waste parameters. Values of effective moisture coefficients were in the range of 1.97-6.05 × 10(-9)m(2)s(-1) under the studied conditions. Activation energy was found to be 28.24 kJ mol(-1). The Weibull model was successfully applied (r(2)>0.973). Specific energy consumption decreased as temperature increased, showing the effect of drying times over temperature. Although dehydrated samples decreased the initial total phenolic content, significant differences were not detected. Effects of drying temperatures did not present significant differences on antioxidant capacity (ORAC and DPPH) when compared to fresh samples. The oleic acid (main fatty acid in fresh samples) presented a maximum increased at 90°C.
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Oskar is targeted for degradation by the sequential action of Par-1, GSK-3, and the SCF?Slimb ubiquitin ligase.
Dev. Cell
PUBLISHED: 01-22-2013
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Translation of oskar messenger RNA (mRNA) is activated at the posterior of the Drosophila oocyte, producing Long Oskar, which anchors the RNA, and Short Oskar, which nucleates the pole plasm, containing the posterior and germline determinants. Here, we show that Oskar is phosphorylated by Par-1 and GSK-3/Shaggy to create a phosphodegron that recruits the SCF(-Slimb) ubiquitin ligase, which targets Short Oskar for degradation. Phosphorylation site mutations cause Oskar overaccumulation, leading to an increase in pole cell number and embryonic patterning defects. Furthermore, the nonphosphorylatable mutant produces bicaudal embryos when oskar mRNA is mislocalized. Thus, the Par-1/GSK-3/Slimb pathway plays important roles in limiting the amount of pole plasm posteriorly and in degrading any mislocalized Oskar that results from leaky translational repression. These results reveal that Par-1 controls the timing of pole plasm assembly by promoting the localization of oskar mRNA but inhibiting the accumulation of Short Oskar protein.
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Intraparenchymal schwannoma involving the brainstem in a young woman.
Pediatr. Neurol.
PUBLISHED: 01-16-2013
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Schwannomas are tumors derived from the Schwann cells, which form the myelin sheath of the peripheral nerves. Fewer than 1% of these tumors occur within the brain parenchyma without arising from the cranial nerves. Only 55 cases have been published after the first recorded case. We report a 17-year-old girl with a 3-month history of unspecific dizziness, unsteadiness, and headache. Magnetic resonance imaging showed a heterogeneous cystic lesion involving midbrain, pons, and left cerebellar peduncle. The patient underwent a retromastoid craniotomy with complete resection of the tumor. Pathologic examination was compatible with intraparenchymal schwannoma. Since the first case of intraparenchymal schwannoma involving the brainstem was described in 1980, only seven others have been reported. Diagnosis of intraparenchymal schwannoma is almost never made preoperatively. Immunohistochemical staining is crucial in distinguishing a Schwannoma from a meningioma, glial tumor, or metastatic tumor. Pathologic findings are those typical of acoustic neurinomas. Histogenesis of intraparenchymal schwannoma remains unclear, and several theories have been proposed to explain their origin. The recognition of this curable tumor and its differentiation from brainstem glioma, which generally has a less favorable outcome, is of obvious importance.
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Influence of air-drying temperature on drying kinetics, colour, firmness and biochemical characteristics of Atlantic salmon (Salmo salar L.) fillets.
Food Chem
PUBLISHED: 01-15-2013
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In this work the drying kinetics of Atlantic salmon (Salmo salar L.) fillets and the influence of air drying temperature on colour, firmness and biochemical characteristics were studied. Experiments were conducted at 40, 50 and 60°C. Effective moisture diffusivity increased with temperature from 1.08×10(-10) to 1.90×10(-10) m(2) s(-1). The colour difference, determined as ?E values (from 9.3 to 19.3), as well as firmness (from 25 to 75 N mm(-1)) of dried samples increased with dehydration temperature. The lightness value L(?) and yellowness value b(?) indicated formation of browning products at higher drying temperatures, while redness value a(?) showed dependence on astaxanthin value. Compared with fresh fish samples, palmitic acid and tocopherol content decreased in a 20% and 40%, respectively, with temperature. While eicosapentaenoic acid (EPA) content remained unchanged and docosahexaenoic acid (DHA) content changed slightly. Anisidine and thiobarbituric acid values indicated the formation of secondary lipid oxidation products, which is more relevant for longer drying time than for higher drying temperatures.
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[Nutrition iodine status in pregnant women in the sanitary district Sierra de Huelva-Andévalo, South of Spain].
Rev. Invest. Clin.
PUBLISHED: 12-05-2011
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Iodine is an essential trace element implicated in synthesis of thyroid hormones. Iodine requirements vary throughout life. This iodine requirement is increased during pregnancy and breastfeeding. In a previous study carried out by our group in 2008, we detected an iodine-deficient area in the province of Huelva, specially in district Sierra de Huelva-Andévalo by means of neonatal TSH determinations.
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[Social-sanitary situation in Marañóns work in the context of the fight against infectious diseases].
Asclepio
PUBLISHED: 10-25-2011
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Gregorio Marañón y Posadillo (1887-1960), played a leading role in the birth of endocrinology in Spain as is well known. However, his medical work included other important and significant fields. Thus, it was especially in the 1910s and 1920s, when Marañón dealt with the social-sanitary situation in madrid probably due to his professional attachment to the treatment of several infectious diseases and epidemic outbreaks. Actually, since 1911 onwards, he was in charge of the wards of infectious diseases in the Hospital General de Madrid where he had the opportunity of treating an important number of patients suffering from this type of pathology and, as a consequence, in the following years he published several articles in medical journals and presented in the Royal Academy of Medicine in Spain, some reports on infectious diseases and the Spanish health and social conditions at the time. This paper try to analyze this field of Marañóns social and scientific activity.
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Rational design and synthesis of aminopiperazinones as ?-secretase (BACE) inhibitors.
Bioorg. Med. Chem. Lett.
PUBLISHED: 09-22-2011
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Aminopiperazinone inhibitors of BACE were identified by rational design. Structure based design guided idea prioritization and initial racemic hit 18a showed good activity. Modification in decoration and chiral separation resulted in the 40 nM inhibitor, (-)-37, which showed in vivo reduction of amyloid beta peptides. The crystal structure of 18a showed a binding mode driven by interaction with the catalytic aspartate dyad and distribution of the biaryl amide decoration towards S1 and S3 pockets.
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Latent tuberculosis infection, tuberculin skin test and vitamin D status in contacts of tuberculosis patients: a cross-sectional and case-control study.
BMC Infect. Dis.
PUBLISHED: 07-04-2011
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Deficient serum vitamin D levels have been associated with incidence of tuberculosis (TB), and latent tuberculosis infection (LTBI). However, to our knowledge, no studies on vitamin D status and tuberculin skin test (TST) conversion have been published to date. The aim of this study was to estimate the associations of serum 25-hydroxyvitamin D3 (25[OH]D) status with LTBI prevalence and TST conversion in contacts of active TB in Castellon (Spain).
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The photoreceptive cells of the pineal gland in adult zebrafish (Danio rerio).
Microsc. Res. Tech.
PUBLISHED: 05-30-2011
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The zebrafish pineal gland plays a fundamental role in the regulation of the circadian rhythm through the melatonin secretion. The pinealocytes, also called photoreceptive cells, are considered the morphofunctional unit of pineal gland. In literature, the anatomical features, the cellular characteristics, and the pinealocytes morphology of zebrafish pineal gland have not been previously described in detail. Therefore, this study was undertaken to analyze the structure and ultrastructure, as well as the immunohistochemical profile of the zebrafish pineal gland with particular reference to the pinealocytes. Here, we demonstrated, using RT-PCR, immunohistochemistry and transmission electron microscopy, the expression of the mRNA for rhodopsin in the pineal gland of zebrafish, as well as its cellular localization exclusively in the pinealocytes of adult zebrafish. Moreover, the ultrastructural observations demonstrated that the pinealocytes were constituted by an outer segment with numerous lamellar membranes, an inner segment with many mitochondria, and a basal pole with the synapses. Our results taken together demonstrated a central role of zebrafish pinealocytes in the control of pineal gland functions.
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Efficient and robust nonlocal means denoising of MR data based on salient features matching.
Comput Methods Programs Biomed
PUBLISHED: 05-25-2011
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The nonlocal means (NLM) filter has become a popular approach for denoising medical images due to its excellent performance. However, its heavy computational load has been an important shortcoming preventing its use. NLM works by averaging pixels in nonlocal vicinities, weighting them depending on their similarity with the pixel of interest. This similarity is assessed based on the squared difference between corresponding pixels inside local patches centered at the locations compared. Our proposal is to reduce the computational load of this comparison by checking only a subset of salient features associated to the pixels, which suffice to estimate the actual difference as computed in the original NLM approach. The speedup achieved with respect to the original implementation is over one order of magnitude, and, when compared to more recent NLM improvements for MRI denoising, our method is nearly twice as fast. At the same time, we evidence from both synthetic and in vivo experiments that computing of appropriate salient features make the estimation of NLM weights more robust to noise. Consequently, we are able to improve the outcomes achieved with recent state of the art techniques for a wide range of realistic Signal-to-Noise ratio scenarios like diffusion MRI. Finally, the statistical characterization of the features computed allows to get rid of some of the heuristics commonly used for parameter tuning.
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Influence of noise correlation in multiple-coil statistical models with sum of squares reconstruction.
Magn Reson Med
PUBLISHED: 04-26-2011
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Noise in the composite magnitude signal from multiple-coil systems is usually assumed to follow a noncentral ? distribution when sum of squares is used to combine images sensed at different coils. However, this is true only if the variance of noise is the same for all coils, and no correlation exists between them. We show how correlations may be obviated from this model if effective values are considered. This implies a reduced effective number of coils and an increased effective variance of noise. In addition, the effective variance of noise becomes signal-dependent.
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Least squares for diffusion tensor estimation revisited: propagation of uncertainty with Rician and non-Rician signals.
Neuroimage
PUBLISHED: 04-05-2011
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Least Squares (LS) and its minimum variance counterpart, Weighted Least Squares (WLS), have become very popular when estimating the Diffusion Tensor (DT), to the point that they are the standard in most of the existing software for diffusion MRI. They are based on the linearization of the Stejskal-Tanner equation by means of the logarithmic compression of the diffusion signal. Due to the Rician nature of noise in traditional systems, a certain bias in the estimation is known to exist. This artifact has been made patent through some experimental set-ups, but it is not clear how the distortion translates in the reconstructed DT, and how important it is when compared to the other source of error contributing to the Mean Squared Error (MSE) in the estimate, i.e. the variance. In this paper we propose the analytical characterization of log-Rician noise and its propagation to the components of the DT through power series expansions. We conclude that even in highly noisy scenarios the bias for log-Rician signals remains moderate when compared to the corresponding variance. Yet, with the advent of Parallel Imaging (pMRI), the Rician model is not always valid. We make our analysis extensive to a number of modern acquisition techniques through the study of a more general Non Central-Chi (nc-?) model. Since WLS techniques were initially designed bearing in mind Rician noise, it is not clear whether or not they still apply to pMRI. An important finding in our work is that the common implementation of WLS is nearly optimal when nc-? noise is considered. Unfortunately, the bias in the estimation becomes far more important in this case, to the point that it may nearly overwhelm the variance in given situations. Furthermore, we evidence that such bias cannot be removed by increasing the number of acquired gradient directions. A number of experiments have been conducted that corroborate our analytical findings, while in vivo data have been used to test the actual relevance of the bias in the estimation.
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Daytime reactions of 1,8-cineole in the troposphere.
Chemphyschem
PUBLISHED: 01-28-2011
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Relative rate coefficients for the gas-phase reaction of chlorine atoms (Cl) and hydroxyl radicals (OH) with 1,8-cineole were determined by Fourier-transform infrared (FTIR) spectroscopy between 285 and 313 K at atmospheric pressure. The temperature dependence of both reactions shows simple Arrhenius behaviour which can be represented by the following expressions (in units of cm(3) molecule(-1) s(-1)): k(1,8-cineole+OH)=(6.28 ± 6.53) × 10(-8) exp[(-2549.3 ± 155.7)/T] and k(1,8-cineole+Cl)=(1.35 ± 1.07) × 10(-10) exp[(-151.6 ± 237.7)/T]. Major products of the titled reactions were identified by solid-phase microextraction (SPME) coupled to a GC-MS. Additionally, the first step of the reaction was theoretically studied by ab initio calculations and a reaction mechanism is proposed.
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NURBS for the geometrical modeling of a new family of Compact-Supported Radial Basis Functions for elastic registration of medical images.
Conf Proc IEEE Eng Med Biol Soc
PUBLISHED: 11-25-2010
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In this paper we propose a novel approach to design a family of Radial Basis Functions with Compact Support applied to elastic registration of medical images. The proposed method is based on Non-Uniform Rational B-Spline theory, which introduce a number of practical properties. The proposed method allows to design almost perfect equally distributed functions which fulfill most of the requirements identified in the recent literature. The Radial Basis Function is merely parametrized by the symmetric desired curvature at peak-and-tails. Properties of the function are numerically compared with foregoing RBFs. Preliminary experimental results indicate its suitability and benefits in registration of medical images.
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DWI acquisition schemes and diffusion tensor estimation: a simulation-based study.
Conf Proc IEEE Eng Med Biol Soc
PUBLISHED: 11-25-2010
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Diffusion Tensor Imaging (DTI) is the most used paradigm among the Diffusion Weighted Magnetic Resonance Imaging techniques, due to its inner simplicity and huge application potential. Least Squares has become the standard technique to estimate the Diffusion Tensor (DT) from Diffusion Weighted Images. This approach is known to be optimal when the acquired data follows Gaussian, Rician or non-central chi distributions. In this paper we study the effect of different acquisition schemes over the quality of the DT estimation. The following cases are considered: single coil, multiple coil fully sampled, and accelerated subsampled multiple coil acquisitions with SENSE and GRAPPA reconstructions. Reconstructed subsampled data will show an acceleration in the acquisition process, but also greater variance and bias in the DT estimation.
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Premenstrual asthma and symptoms related to premenstrual syndrome.
J Asthma
PUBLISHED: 09-30-2010
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It is unclear whether premenstrual asthma is associated with premenstrual syndrome. The objective of this study is to compare premenstrual symptoms among asthmatic women according to whether they have premenstrual asthma or not.
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Nutrition facts and functional potential of quinoa (Chenopodium quinoa willd.), an ancient Andean grain: a review.
J. Sci. Food Agric.
PUBLISHED: 09-04-2010
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Quinoa, Chenopodium quinoa Willd., is an Amaranthacean, stress-tolerant plant cultivated along the Andes for the last 7000 years, challenging highly different environmental conditions ranging from Bolivia, up to 4.500 m of altitude, to sea level, in Chile. Its grains have higher nutritive value than traditional cereals and it is a promising worldwide cultivar for human consumption and nutrition. The quinoa has been called a pseudo-cereal for botanical reasons but also because of its unusual composition and exceptional balance between oil, protein and fat. The quinoa is an excellent example of functional food that aims at lowering the risk of various diseases. Functional properties are given also by minerals, vitamins, fatty acids and antioxidants that can make a strong contribution to human nutrition, particularly to protect cell membranes, with proven good results in brain neuronal functions. Its minerals work as cofactors in antioxidant enzymes, adding higher value to its rich proteins. Quinoa also contains phytohormones, which offer an advantage over other plant foods for human nutrition.
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Insight into the phenomenology of the Cr(VI) reduction by metallic iron using an electron probe microanalyzer.
Langmuir
PUBLISHED: 06-29-2010
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Research was performed to gain insight into the heterogeneous reaction of Cr(VI) reduction by zero-valent iron, which is frequently used in the treatment of contaminated groundwater using permeable reactive barriers. An electron probe microanalyzer was used to clarify in detail relevant aspects of the reaction with consequences for the conception of interpretative kinetic models. Spherical particles of iron with controlled grain sizes were used after being subjected to a previous washing with diluted acid in order to remove oxidation products. These spheres were immersed in solutions of Cr(VI) in nonagitated flasks using different operating procedures. The iron particles were photographed so that the time evolution of the grain size distribution could be established. A sample of the iron balls after the reaction and samples of the raw material and the precipitates of the reaction products were analyzed by backscattering electron images and elemental mapping produced by wavelength-dispersive spectroscopy. The analysis of the spatial distribution of the concentrations in iron, oxygen, and chromium indicates that there are three distinct mechanisms for the reaction with different limiting steps.
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Discovery of 1,5-disubstituted pyridones: a new class of positive allosteric modulators of the metabotropic glutamate 2 receptor.
ACS Chem Neurosci
PUBLISHED: 06-21-2010
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A series of 1,5-disubstituted pyridones was identified as positive allosteric modulators (PAMs) of the metabotropic glutamate receptor 2 (mGluR2) via high throughput screening (HTS). Subsequent SAR exploration led to the identification of several compounds with improved in vitro activity. Lead compound 8 was further profiled and found to attenuate the increase in PCP induced locomotor activity in mice.
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Statistical noise analysis in GRAPPA using a parametrized noncentral Chi approximation model.
Magn Reson Med
PUBLISHED: 05-21-2010
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The characterization of the distribution of noise in the magnitude MR image is a very important problem within image processing algorithms. The Rician noise assumed in single-coil acquisitions has been the keystone for signal-to-noise ratio estimation, image filtering, or diffusion tensor estimation for years. With the advent of parallel protocols such as sensitivity encoding or Generalized Autocalibrated Partially Parallel Acquisitions that allow accelerated acquisitions, this noise model no longer holds. Since Generalized Autocalibrated Partially Parallel Acquisitions reconstructions yield the combination of the squared signals recovered at each receiving coil, noncentral Chi statistics have been previously proposed to model the distribution of noise. However, we prove in this article that this is a weak model due to several artifacts in the acquisition scheme, mainly the correlation existing between the signals obtained at each coil. Alternatively, we propose to model such correlations with a reduction in the number of degrees of freedom of the signal, which translates in an equivalent nonaccelerated system with a minor number of independent receiving coils and, consequently, a lower signal-to-noise ratio. With this model, a noncentral Chi distribution can be assumed for all pixels in the image, whose effective number of coils and effective variance of noise can be explicitly computed in a closed form from the Generalized Autocalibrated Partially Parallel Acquisitions interpolation coefficients. Extensive experiments over both synthetic and in vivo data sets have been performed to show the goodness of fit of out model.
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Premenstrual asthma and atopy markers.
Ann. Allergy Asthma Immunol.
PUBLISHED: 04-27-2010
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The frequency of atopy in women with premenstrual asthma (PMA) and its possible effect on the premenstrual exacerbation of asthma are unknown.
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Effective moisture diffusivity determination and mathematical modelling of the drying curves of the olive-waste cake.
Bioresour. Technol.
PUBLISHED: 04-13-2010
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Olive cake is an important agro industrial by-product with the dried cake being the input material of many applications areas. In this research, the drying kinetics of olive cake during convective dehydration at five temperatures (50, 60, 70, 80 and 90 degrees C) was investigated. Several empirical mathematical models were selected to describe experimental drying kinetics data, namely, Page, Modified Page, Henderson and Pabis, Modified Henderson and Pabis, Two-Terms, Logarithmic and Weibull. Air temperature showed a significant effect on drying rates. Based on the statistical tests results (sum squared errors, chi-square and correlation coefficients), the Modified Henderson and Pabis equation is the most suitable model to describe the experimental drying curves. Effective moisture diffusivity of olive cake was in the range of 2.03x10(-9)-1.71x10(-9) m(2) s(-1). An activation energy value of 12.43 kJ mol(-1) was determined. The findings allow the successful simulation of olive cake drying between 50 and 90 degrees C.
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About the background distribution in MR data: a local variance study.
Magn Reson Imaging
PUBLISHED: 02-09-2010
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A model for the distribution of the sample local variance (SLV) of magnetic resonance data is proposed. It is based on a bimodal Gamma distribution, whose maxima are related to the signal and background areas of the image. The model is valid for single- and multiple-coil systems. The proposed distribution allows us to characterize some signal/background properties in MR data. As an example, the model is used to study the effect of the background size over noise estimation techniques and a method to test the validity of background-based noise estimators is presented.
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Atmospheric reactions of (H)- and (D)-fluoroalcohols with chlorine atoms.
Chemphyschem
PUBLISHED: 01-06-2010
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The reactions of Cl with a series of fluoroalcohols and deuterated fluoroalcohols, CF(3)CH(2)OH (k(4)), CF(3)CH(OH)CH(3) (k(5)), CF(3)CH(OH)CF(3) (k(6)), CF(3)CH(OD)CF(3) (k(7)) and CF(3)CD(OD)CF(3) (k(8)), are investigated as a function of temperature in the range of 268-378 K by laser photolysis-resonance fluorescence. To our knowledge, only the CF(3)CH(2)OH + Cl reaction has been previously studied from a kinetic point of view. The derived Arrhenius expressions obtained using our kinetic data are: k(4) = (1.79+/-0.17) x 10(-13) exp[(410+/-26)/T], k(5) = (1.20+/-0.11) x 10(-12) exp[(394+/-14)/T], k(6) = (2.32+/-0.18) x 10(-13) exp[-(740+/-12)/T], k(7) = (6.45+/-1.87) x 10(-13) exp[-(1136+/-94)/T] and k(8) = (4.19+/-1.09) x 10(-13) exp[-(1378+/-81)/T] (in units of cm(3) molecule(-1) s(-1) and where errors are +/-sigma). Moreover, a theoretical insight into the mechanisms of these reactions is pursued through ab initio Möller-Plesset second-order perturbation treatment calculations with the 6-311G** basis set. Optimized geometries are obtained for reagents, transition states and molecular complexes appearing along the different reaction pathways. Furthermore, molecular energies are calculated at the quadratic configuration interaction with single, double and triple excitations [QCISD(T)] level to obtain an estimation of the activation energies. Finally, the rate constants are calculated through transition-state theory using Wigners transmission coefficient in order to include the tunnelling-effect corrections.
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BDNF is essentially required for the early postnatal survival of nociceptors.
Dev. Biol.
PUBLISHED: 01-05-2010
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Neurotrophins promote the survival of specific types of neurons during development and ensure proper maintenance and function of mature responsive neurons. Significant effects of BDNF (Brain-Derived Neurotrophic Factor) on pain physiology have been reported but the contribution of this neurotrophin to the development of nociceptors has not been investigated. We present evidence that BDNF is required for the survival of a significant fraction of peptidergic and non-peptidergic nociceptors in dorsal root ganglia (DRG) postnatally. Bdnf homozygous mutant mice lose approximately half of all nociceptive neurons during the first 2 weeks of life and adult heterozygotes exhibit hypoalgesia and a loss of 25% of all nociceptive neurons. Our in vitro analyses indicate that BDNF-dependent nociceptive neurons also respond to NGF and GDNF. Expression analyses at perinatal times indicate that BDNF is predominantly produced within sensory ganglia and is more abundant than skin-derived NGF or GDNF. Function-blocking studies with BDNF specific antibodies in vitro or cultures of BDNF-deficient sensory neurons suggest that BDNF acts in an autocrine/paracrine way to promote the early postnatal survival of nociceptors that are also responsive to NGF and GDNF. Altogether, the data demonstrate an essential requirement for BDNF in the early postnatal survival of nociceptive neurons.
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Detection of Panulirus argus Virus 1 (PaV1) in exported frozen tails of subadult-adult Caribbean spiny lobsters Panulirus argus.
Dis. Aquat. Org.
PUBLISHED: 11-12-2009
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The Caribbean spiny lobster Panulirus argus is a valuable fishing resource and the trade in frozen lobster tails is an important industry. However, the presence of the pathogenic virus Panulirus argus Virus 1 (PaV1), which causes systemic infection in P. argus and is particularly lethal to juvenile individuals, has not been previously examined in imported/exported lobster products. We used PCR assays to determine the presence of PaV1 in abdominal muscle tissue of 22 frozen P. argus tails exported from Belize to Mexico. Based on their size, the tails belonged to subadult-adult lobsters. Using specific primers targeted for PaV1 resulted in 11 tails showing a specific 499 bp band. The sequence of positive amplified fragments showed a high similarity to PaV1 (95% identity with GenBank accession no. EF206313.1). Although the pathogenicity of PaV1 was not evaluated in the present study, our results provide the first evidence of PaV1 in frozen lobster tails exported in the seafood industry as well as the first molecular evidence of PaV1 in adult lobsters.
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Scaffold hopping from pyridones to imidazo[1,2-a]pyridines. New positive allosteric modulators of metabotropic glutamate 2 receptor.
Bioorg. Med. Chem. Lett.
PUBLISHED: 10-07-2009
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Imidazo[1,2-a]pyridines were identified via their shape and electrostatic similarity as novel positive allosteric modulators of the metabotropic glutamate 2 receptor. The subsequent synthesis and SAR are described. Potent, selective and metabolically stable compounds were found representing a promising avenue for current further studies.
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Angiotensin II induces CD62L shedding in human neutrophils.
Atherosclerosis
PUBLISHED: 09-23-2009
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Studies indicate that both alterations in leukocyte and endothelial cell adhesion molecules and the renin angiotensin system are involved in the pathogenesis of atherosclerosis processes in human hypertension. The present work was undertaken to investigate whether angiotensin II (Ang II) regulates the expression of CD62L on human neutrophils. Human neutrophils were stimulated with Ang II in the presence of various AT1-receptor antagonists and protein kinase inhibitors, and CD62L cell surface expression was detected by flow cytometry. We report for the first time that Ang II down-regulated CD62L from the surface of human neutrophils, a process which was independent of neutrophil adhesion to endothelium since neutrophils were still able to adhere to human umbilical vein endothelial cells even under doses that almost completely release CD62L from the cell surface. This process occurred through pathways involving AT1 receptors, extracellular signal-regulated kinases 1 and 2 mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase, and calcineurin, ruling out a role for p38 MAPK and small GTPases in the process.
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DWI filtering using joint information for DTI and HARDI.
Med Image Anal
PUBLISHED: 08-05-2009
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The filtering of the Diffusion Weighted Images (DWI) prior to the estimation of the diffusion tensor or other fiber Orientation Distribution Functions (ODF) has been proved to be of paramount importance in the recent literature. More precisely, it has been evidenced that the estimation of the diffusion tensor without a previous filtering stage induces errors which cannot be recovered by further regularization of the tensor field. A number of approaches have been intended to overcome this problem, most of them based on the restoration of each DWI gradient image separately. In this paper we propose a methodology to take advantage of the joint information in the DWI volumes, i.e., the sum of the information given by all DWI channels plus the correlations between them. This way, all the gradient images are filtered together exploiting the first and second order information they share. We adapt this methodology to two filters, namely the Linear Minimum Mean Squared Error (LMMSE) and the Unbiased Non-Local Means (UNLM). These new filters are tested over a wide variety of synthetic and real data showing the convenience of the new approach, especially for High Angular Resolution Diffusion Imaging (HARDI). Among the techniques presented, the joint LMMSE is proved a very attractive approach, since it shows an accuracy similar to UNLM (or even better in some situations) with a much lighter computational load.
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A new methodology for the estimation of fiber populations in the white matter of the brain with the Funk-Radon transform.
Neuroimage
PUBLISHED: 06-13-2009
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The Funk-Radon Transform (FRT) is a powerful tool for the estimation of fiber populations with High Angular Resolution Diffusion Imaging (HARDI). It is used in Q-Ball imaging (QBI), and other HARDI techniques such as the recent Orientation Probability Density Transform (OPDT), to estimate fiber populations with very few restrictions on the diffusion model. The FRT consists in the integration of the attenuation signal, sampled by the MRI scanner on the unit sphere, along equators orthogonal to the directions of interest. It is easily proved that this calculation is equivalent to the integration of the diffusion propagator along such directions, although a characteristic blurring with a Bessel kernel is introduced. Under a different point of view, the FRT can be seen as an efficient way to compute the angular part of the integral of the attenuation signal in the plane orthogonal to each direction of the diffusion propagator. In this paper, Stokes theorem is used to prove that the FRT can in fact be used to compute accurate estimates of the true integrals defining the functions of interest in HARDI, keeping the diffusion model as little restrictive as possible. Varying the assumptions on the attenuation signal, we derive new estimators of fiber orientations, generalizing both Q-Balls and the OPDT. Extensive experiments with both synthetic and real data have been intended to show that the new techniques improve existing ones in many situations.
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Saturn: a software application of tensor utilities for research in neuroimaging.
Comput Methods Programs Biomed
PUBLISHED: 05-19-2009
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We present an advanced software tool designed for visualization and quantitative analysis of Diffusion Tensor Imaging (DTI) called Saturn. The software is specially developed to help clinicians and researchers in neuroimaging, and includes a complete set of visualization capabilities to browse and analyze efficiently DTI data, making this application a powerful tool also for diagnosis purposes. The software includes a robust quantification method for DTI data, using an atlas-based method to automatically obtain equivalent anatomical fiber bundles and regions of interest among different DTI data sets. Consequently, a set of measurements is also implemented to perform robust group studies among subjects affected by neurological disorders and control groups in order to look for significant differences. Finally, a comparison study with five similar DTI applications is presented, showing the advantages offered by this tool.
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Noise estimation in single- and multiple-coil magnetic resonance data based on statistical models.
Magn Reson Imaging
PUBLISHED: 03-31-2009
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Noise estimation is a challenging task in magnetic resonance imaging (MRI), with applications in quality assessment, filtering or diffusion tensor estimation. Main noise estimators based on the Rician model are revisited and classified in this article, and new useful methods are proposed. Additionally, all the surveyed estimators are extended to the noncentral chi model, which applies to multiple-coil MRI and some important parallel imaging algorithms for accelerated acquisitions. The proposed new noise estimation procedures, based on the distribution of local moments, show better performance in terms of smaller variance and unbiased estimation over a wide range of experiments, with the additional advantage of not needing to explicitly segment the background of the image.
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Estimation of fiber orientation probability density functions in high angular resolution diffusion imaging.
Neuroimage
PUBLISHED: 03-20-2009
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An estimator of the Orientation Probability Density Function (OPDF) of fiber tracts in the white matter of the brain from High Angular Resolution Diffusion data is presented. Unlike Q-Balls, which use the Funk-Radon transform to estimate the radial projection of the 3D Probability Density Function, the Jacobian of the spherical coordinates is included in the Funk-Radon approximation to the radial integral. Thus, true angular marginalizations are computed, which allows a strict probabilistic interpretation. Extensive experiments with both synthetic and real data show the better capability of our method to characterize complex micro-architectures compared to other related approaches (Q-Balls and Diffusion Orientation Transform), especially for low values of the diffusion weighting parameter.
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[Primary adrenal insufficiency as the form of onset of adrenoleukodystrophy in a 4-year-old boy].
Endocrinol Nutr
PUBLISHED: 03-01-2009
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X-linked adrenoleukodystrophy is an inherited metabolic disease caused by the accumulation of saturated very long chain fatty acids (VLCFA). Given that the form of presentation can be primary adrenal insufficiency, diagnosis in affected males is important. Patient was a 4-year-old boy with attention deficit hyperactivity disorder, cutaneous-mucosal hyperpigmentation, and dehydration with hyponatremia and hyperpotassemia was diagnosed with adrenoleukodystrophy presenting as primary adrenal insufficiency. Antiadrenal antibodies: negative. Plasma VLCFA: C(26:0)=1.25mg/ml (0.18-0.48), C(24:0)/C(22:0) =1.53 (< 1), and C(26:0)/ C(22:0)=0.04 (< 0.02). Abdominal computed tomography: small adrenal glands. Cranial magnetic resonance imaging and evoked potentials: normal at diagnosis and with signs of white matter demyelination after 2 years of follow-up. Testing for an autoimmune etiology and adrenoleukodystrophy is important in boys with primary adrenal insufficiency before Addisons disease is diagnosed.
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Physiological and immunological characterization of Caribbean spiny lobsters Panulirus argus naturally infected with Panulirus argus Virus 1 (PaV1).
Dis. Aquat. Org.
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The present study compares 13 physiological and immunological variables between a group of healthy Panulirus argus lobsters and a group of lobsters naturally infected with Panulirus argus Virus 1 (PaV1). Viral infection was determined through histopathology and PCR. Ten of the 13 variables differed significantly between the 2 groups. Using these variables, a principal component analysis yielded 2 separate clusters: one corresponding to the healthy group and the other corresponding to the infected group. In particular, infected lobsters exhibited significantly lower levels of osmotic pressure, total hemocyte counts, plasmatic proteins, and total phenoloxidase (PO) activity in plasma, as well as significantly higher levels of cholesterol and acylglycerides. These features are consistent with metabolic wasting, hyperlipidemia, and presumed immune suppression. Infection with PaV1 appears to increase the susceptibility of lobsters to some other opportunistic pathogens, as 61.1% of infected lobsters presented infestations of ciliate epibionts (Epystilis and Zoothamniun) in the gill chamber compared with 11.5% lobsters in the healthy group. Infected lobsters also showed significantly higher levels of total PO activity in degranulated hemocytes and trypsin inhibitor activity, potentially indicating activation of immune response by the PO system during the systemic infection with PaV1.
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[Quality of life following surgical treatment of malignant middle cerebral artery infarction].
Rev Neurol
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Little work has been published on the capacity to adapt to the disease of patients with malignant middle cerebral artery infarction who have undergone decompressive surgery. The purpose of this study is to analyse the final quality of life and the degree of satisfaction of patients and their relatives.
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Evidence of nestin-positive cells in the human cutaneus Meissner and Pacinian corpuscles.
CNS Neurol Disord Drug Targets
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Nestin is an intermediate filament protein expressed in neuroepithelial stem cells during development and it is later replaced by cell specific neuronal or glial filaments. Nevertheless, nestin? cells remain within adult tissues and they can be regarded as potential neural stem cell (NSC). Nestin? cells have been detected in Schwann cells related with sensory corpuscles of rodent and they have been demonstrated to be NSC. We have investigated the existence of nestin? in human cutaneous cells Meissner and Pacinian corpuscles through the use of immunohistochemistry techniques and in situ hybridization. S100 protein (also regarded as a marker for NSC) and vimentin (the intermediate filament of mature Schwann cells in sensory corpuscles) were also investigated. The results show that the adult human cutaneous sensory Meissner and Pacinian corpuscles contains a small population of Schwann-related cells (vimentin?) which on the basis of their basic immunohistochemical characteristics (S100 protein?, nestin?) can be potential NSCs. Cells sharing identical immunohistochemical profile were also found in the close vicinity of Meissner corpuscles. Because their localization they are easily accessible and may represent a peripheral niche of NSC to be used for therapeutic goals.
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Effective noise estimation and filtering from correlated multiple-coil MR data.
Magn Reson Imaging
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Modern magnetic resonance (MR) imaging protocols based on multiple-coil acquisitions have carried on a new attention to noise and signal statistical modeling, as long as most of the existing techniques for data processing are model based. In particular, nonaccelerated multiple-coil and GeneRalized Autocalibrated Partially Parallel Acquisitions (GRAPPA) have brought noncentral-? (nc-?) statistics into stake as a suitable substitute for traditional Rician distributions. However, this model is only valid when the signals received by each coil are roughly uncorrelated. The recent literature on this topic suggests that this is often not the case, so nc-? statistics are in principle not adequate. Fortunately, such model can be adapted through the definition of a set of effective parameters, namely, an effective noise power (greater than the actual power of thermal noise in the Radio Frequency receiver) and an effective number of coils (smaller than the actual number of RF receiving coils in the system). The implications of these artifacts in practical algorithms have not been discussed elsewhere. In the present paper, we aim to study their actual impact and suggest practical rules to cope with them. We define the main noise parameters in this context, introducing a new expression for the effective variance of noise which is of capital importance for the two image processing problems studied: first, we propose a new method to estimate the effective variance of noise from the composite magnitude signal of MR data when correlations are assumed. Second, we adapt several model-based image denoising techniques to the correlated case using the noise estimation techniques proposed. We show, through a number of experiments with synthetic, phantom, and in vivo data, that neglecting the correlated nature of noise in multiple-coil systems implies important errors even in the simplest cases. At the same time, the proper statistical characterization of noise through effective parameters drives to improved accuracy (both qualitatively and quantitatively) for both of the problems studied.
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Design of a three-dimensional multitarget activity landscape.
J Chem Inf Model
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The design of activity landscape representations is challenging when compounds are active against multiple targets. Going beyond three or four targets, the complexity of underlying activity spaces is difficult to capture in conventional activity landscape views. Previous attempts to generate multitarget activity landscapes have predominantly utilized extensions of molecular network representations or plots of activity versus chemical similarity for pairs of active compounds. Herein, we introduce a three-dimensional multitarget activity landscape design that is based upon principles of radial coordinate visualization. Circular representations of multitarget activity and chemical reference space are combined to generate a spherical view into which compound sets are projected for interactive analysis. Interpretation of landscape content is facilitated by following three canonical views of activity, chemical, and combined activity/chemical space, respectively. These views focus on different planes of the underlying coordinate system. From the activity and combined views, compounds with well-defined target selectivity and structure-activity profile relationships can be extracted. In the activity landscape, such compounds display characteristic spatial arrangements and target activity patterns.
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Discovery of 3-cyclopropylmethyl-7-(4-phenylpiperidin-1-yl)-8-trifluoromethyl[1,2,4]triazolo[4,3-a]pyridine (JNJ-42153605): a positive allosteric modulator of the metabotropic glutamate 2 receptor.
J. Med. Chem.
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Advanced leads from a series of 1,2,4-triazolo[4,3-a]pyridines with mGlu2 receptor PAM activity are reported. By modification of the analogous imidazo[1,2-a]pyridine series, the newly reported leads have improved potency, in vitro ADMET, and hERG as well as good in vivo PK profile. The optimization of the series focused on improving metabolic stability while controlling lipophilicity by introducing small modifications to the scaffold substituents. Analysis of this series combined with our previously reported mGlu2 receptor PAMs showed how lipophilic ligand efficiency was improved during the course of the program. Among the best compounds, example 20 (JNJ-42153605) showed a central in vivo efficacy by inhibition of REM sleep state at a dose of 3 mg/kg po in the rat sleep-wake EEG paradigm, a phenomenon shown earlier to be mGlu2 mediated. In mice, compound 20 reversed PCP-induced hyperlocomotion with an ED?? of 5.4 mg/kg sc, indicative of antipsychotic activity.
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[Spatial distribution of Ocypode quadrata (Decapoda: Ocypodidae) in eight beaches of North-Eastern Cuba].
Rev. Biol. Trop.
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Studies on the ecology of Ocypode quadrata have been mostly carried out in the Northern and Southern part of its distribution range. In despite that this species is common in Cuban beaches, there are no quantitative studies regarding its abundance and spatial distribution. The aim of this study was to report some aspects about the spatial variation of O. quadrata density in sandy beaches, with different levels of human influence, in the North coast of Eastern Cuba. For this, on May 2010, eight beaches with different levels of human influence were surveyed. On each beach, the number of crabs burrows were counted in 45 quadrats of 4m2 located in three different strata (P1, P2 and P3). According to burrow opening diameter, crabs were separated into young and adults forms. To determine the existence of statistical differences in the density of crab burrows among beaches and strata, a two-way ANOVA was developed with a Scheffé-procedure post hoc test. A total of 355 burrows were counted in 360 sample units. The composition by size classes was 237 burrows for young and 118 for adults. From the total of burrows, 74% were located in P1, 20% in P2 and 6% in P3. The higher concentration of burrows was found at Jiguaní beach (0.52 +/- 0.08 burrows/m2) while the lesser concentration was found at Estero Ciego beach (0.06 +/- 0.01 burrows/m2). Most of the beaches did not present significant differences in the burrows density (Scheffé, p>0.05), according to ANOVA results, in despite their different human influence level. Density of individuals was significantly higher in the upper intertidal (P1) areas (Scheffé, p<0.05) with predominance of young crabs. Total density diminished in P2 and P3 strata where a predominance of adult individuals was observed. The interaction term of beach and strata evidenced that the pattern of variation among strata was not the same for all beaches. The general pattern of adults and young specimen spatial distribution in the beaches was very similar to those reported in the literature. In the present study, the first conducted in Cuban beaches, we did not find evidence of direct relationship between the level of human impact and the density of ghost crab burrows.
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Microbiological stabilization of Aloe vera (Aloe barbadensis Miller) gel by high hydrostatic pressure treatment.
Int. J. Food Microbiol.
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The effect of high hydrostatic pressure (HHP) treatment (300, 400 and 500 MPa for 1 and 3 min at 20 °C) on the microbiological shelf-life and microbiota composition of Aloe vera gel during 90 days of storage at 4 °C was investigated. Aerobic mesophilic and psychrotrophic bacteria, as well as moulds and yeasts, were enumerated after HHP treatment and through cold storage. Randomly selected isolates from the count plates were identified by standard methods and the API identification system. Results showed that HHP treatment at or over 400 MPa for 3 min were effective to keep the microbial counts to undetectable levels during the whole storage period, and consequently the microbiological shelf-life of A. vera gel was extended for more than 90 days at 4 °C. The microbiota in the untreated A. vera gel was dominated by Gram-negative bacteria (mostly Rahnella aquatilis) and yeasts (mostly Rhodotorula mucilaginosa). In contrast, Gram-positive bacteria tentatively identified as Arthrobacter spp. and Micrococcus/Kocuria spp. were the predominant microorganisms in samples pressurized at 300 MPa for 1 and 3 min, while Bacillus megaterium predominating in samples treated at 400 MPa for 1 min. At 400 MPa for 3 min and above, the microbial growth was completely suppressed during at least 90 days; however, viable spore-formers were detected by enrichment.
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Kinetics and mechanisms of the tropospheric reactions of menthol, borneol, fenchol, camphor, and fenchone with hydroxyl radicals (OH) and chlorine atoms (Cl).
J Phys Chem A
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Relative kinetic techniques have been used to measure the rate coefficients for the reactions of oxygenated terpenes (menthol, borneol, fenchol, camphor, and fenchone) and cyclohexanol with hydroxyl radicals (OH) and chlorine atoms (Cl) at 298 ± 2 K and atmospheric pressure. The rate coefficients obtained for the reactions of the title compounds with OH are the following (in units of 10(-11) cm(3) molecule(-1) s(-1)): (1.48 ± 0.31), (2.65 ± 0.32), (2.49 ± 0.30), (0.38 ± 0.08), (0.39 ± 0.09) for menthol, borneol, fenchol, camphor, and fenchone, respectively. For the corresponding reactions with Cl atoms the rate coefficients are as follows (in units of 10(-10) cm(3) molecule(-1) s(-1)): (3.21 ± 0.26), (3.40 ± 0.28), (2.72 ± 0.13), (2.93 ± 0.17), (1.59 ± 0.10), and (1.86 ± 0.29) for cyclohexanol, menthol, borneol, fenchol, camphor, and fenchone, respectively. The reported error is twice the standard deviation. Product studies of the reactions were performed using multipass in situ FTIR (Fourier transform infrared spectroscopy) and solid-phase microextraction (SPME) with analysis by GC-MS (gas chromatography-mass spectrometry). A detailed mechanism is proposed to justify the observed reaction products.
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Non-lethal detection of DNA from Cichlidogyrus spp. (Monogenea, Ancyrocephalinae) in gill mucus of the Nile tilapia Oreochromis niloticus.
Dis. Aquat. Org.
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Infection of Nile tilapia Oreochromis niloticus by monogeneans of the genus Cichlidogyrus is harmful. Currently, diagnosis of this infection is based on invasive techniques and the identification of isolated parasites by their morphology. To facilitate diagnosis, we have developed a non-lethal polymerase chain reaction (PCR) test for detection of Cichlidogyrus spp. DNA in the gill mucus of O. niloticus, using 5 pairs of specific primers based on Cichlidogyrus sclerosus 28S rRNA (Cicly 1 to Cicly 5) which generate fragments of approximately 188, 180, 150, 159 and 189 bp, respectively. PCR specificity was tested using genomic DNA extracted individually from 175 isolated Cichlidogyrus spp., 75 Gyrodactylus cichlidarum and 75 endopararasitic Enterogyrus spp., as well as from 75 protozoans Trichodina spp. The Cicly primers were used to detect Cichlidogyrus spp. DNA in mucus from the gills of 23 Nile tilapia confirmed to be infected with the parasite. Negative controls consisted of 45 uninfected Nile tilapia. The limit of sensitivity of the assay was 1.2 ng of purified parasite DNA. The Cicly primers did not amplify DNA from the mucus of non-infected Nile tilapia, G. cichlidarum, Trichodina spp. or Enterogyrus spp. In all cases, the sensitivity and specificity of the test were 100%. The sequences of all the amplified fragments showed a high similarity to that of the 28S rRNA region of C. sclerosus (93 to 100% identical to GenBank Accession No. DQ157660.1). We provide evidence for a safe and non-invasive DNA-based diagnostic method for the presence of Cichlidogyrus in the gill mucus of O. niloticus.
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Discovery of 1,4-disubstituted 3-cyano-2-pyridones: a new class of positive allosteric modulators of the metabotropic glutamate 2 receptor.
J. Med. Chem.
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The discovery and characterization of compound 48, a selective and in vivo active mGlu2 receptor positive allosteric modulator (PAM), are described. A key to the discovery was the rational exploration of the initial HTS hit 13 guided by an overlay model built with reported mGlu2 receptor PAM chemotypes. The initial weak in vitro activity of the hit 13 was quickly improved, although compounds still had suboptimal druglike properties. Subsequent modulation of the physicochemical properties resulted in compounds having a more balanced profile, combining good potency and in vivo pharmacokinetic properties. Final refinement by addressing cardiovascular safety liabilities led to the discovery of compound 48. Besides good potency, selectivity, and ADME properties, compound 48 displayed robust in vivo activity in a sleep-wake electroencephalogram (sw-EEG) assay consistent with mGlu2 receptor activation, in accordance with previous work from our laboratories.
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Imidazo[1,2-a]pyridines: orally active positive allosteric modulators of the metabotropic glutamate 2 receptor.
J. Med. Chem.
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Advanced leads of an imidazopyridine series of positive allosteric modulators of the metabotropic glutamate 2 (mGlu2) receptor are reported. The optimization of in vitro ADMET and in vivo pharmacokinetic properties led to the identification of 27o. With good potency and selectivity for the mGlu2 receptor, 27o affected sleep-wake architecture in rats after oral treatment, which we have previously shown to be indicative of mGlu2 receptor-mediated central activity.
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Rhodopsin expression in the zebrafish pineal gland from larval to adult stage.
Brain Res.
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The zebrafish pineal gland plays an important role in different physiological functions including the regulation of the circadian clock. In the fish pineal gland the pinealocytes are made up of different segments: outer segment, inner segment and basal pole. Particularly, in the outer segment the rhodopsin participates in the external environment light reception that represents the first biochemical step in the melatonin production. It is well known that the rhodopsin in the adult zebrafish is well expressed in the pineal gland but both the expression and the cellular localization of this protein during development remain still unclear. In this study using qRT-PCR, sequencing and immunohistochemistry the expression as well as the protein localization of the rhodopsin in the zebrafish from larval (10 dpf) to adult stage (90 dpf) were demonstrated. The rhodopsin mRNA expression presents a peak of expression at 10 dpf, a further reduction to 50 dpf before increasing again in the adult stage. Moreover, the cellular localization of the rhodopsin-like protein was always localized in the pinealocyte at all ages examined. Our results demonstrated the involvement of the rhodopsin in the zebrafish pineal gland physiology particularly in the light capture during the zebrafish lifespan.
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Optimal real-time estimation in diffusion tensor imaging.
Magn Reson Imaging
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Diffusion tensor imaging (DTI) constitutes the most used paradigm among the diffusion-weighted magnetic resonance imaging (DW-MRI) techniques due to its simplicity and application potential. Recently, real-time estimation in DW-MRI has deserved special attention, with several proposals aiming at the estimation of meaningful diffusion parameters during the repetition time of the acquisition sequence. Specifically focusing on DTI, the underlying model of the noise present in the acquired data is not taken into account, leading to a suboptimal estimation of the diffusion tensor. In this paper, we propose an optimal real-time estimation framework for DTI reconstruction in single-coil acquisitions. By including an online estimation of the time-changing noise variance associated to the acquisition process, the proposed method achieves the sequential best linear unbiased estimator. Results on both synthetic and real data show that our method outperforms those so far proposed, reaching the best performance of the existing proposals by processing a substantially lower number of diffusion images.
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JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.