Ariel LC - Academia.edu (original) (raw)

Papers by Ariel LC

PLOS Neglected Tropical Diseases, 2011

Exposure of Entamoeba histolytica to specific ligands induces cell polarization via the activatio... more Exposure of Entamoeba histolytica to specific ligands induces cell polarization via the activation of signalling pathways and cytoskeletal elements. The process leads to formation of a protruding pseudopod at the front of the cell and a retracting uropod at the rear. In the present study, we show that the uropod forms during the exposure of trophozoites to serum isolated from humans suffering of amoebiasis. To investigate uropod assembly, we used LC-MS/MS technology to identify protein components in isolated uropod fractions. The galactose/N-acetylgalactosamine lectin, the immunodominant antigen M17 (which is specifically recognized by serum from amoeba-infected persons) and a few other cells adhesionrelated molecules were primarily involved. Actin-rich cytoskeleton components, GTPases from the Rac and Rab families, filamin, a-actinin and a newly identified ezrin-moesin-radixin protein were the main factors found to potentially interact with capped receptors. A set of specific cysteine proteases and a serine protease were enriched in isolated uropod fractions. However, biological assays indicated that cysteine proteases are not involved in uropod formation in E. histolytica, a fact in contrast to the situation in human motile immune cells. The surface proteins identified here are testable biomarkers which may be either recognized by the immune system and/or released into the circulation during amoebiasis.

In light of some recent electron-wake investigations made on the Explorer 31 satellite, it is sug... more In light of some recent electron-wake investigations made on the Explorer 31 satellite, it is suggested that the major part of the (1.5-2) orders of magnitude difference between the Explorer 8 and the Ariel I electron-wake measurements can be removed. behind a mesothermally moving satellite, Nature, 215, 127, 1967. Liu, V. C., Ionospheric gas dynamics of satellites and diagnostic probes, Space Sci. Rev., vol. 9, June 1969. Samir, U., and A. P. Willmore, The distribution of charged particles near a moving spacecraft, Planet. Space $ci., 13, 285, 1965. Samir, U., and A. P. Willmore, The equilibrium potential of a spacecraft in the ioaosphere, Planet. Space Sci., 14, 1131, 1966. Samir, U., and G. L. Wrenn, The dependence of charge and potential distribution around a spacecraft on ionic composition, Planet. Space Sci., 17, 693, 1969. Wake observations on the Gemini-Agena 10 and 11 missions (abstract), Trans. Amer. Geophys. Union, 50(4), 267, 1969. Wrenn, G. L., The Langmuir plate and spherical ion probe experiments aboard Explorer 31, IEEE special issue on Topside Sounding and the Ionosphere, 1072, June 1969.

World Journal of Surgery, 1993

Laparoscopic cholecystectomy is rapidly replacing traditional cholecystectomy as the standard tre... more Laparoscopic cholecystectomy is rapidly replacing traditional cholecystectomy as the standard treatment for cholelithiasis and cholecystitis in adults. Over a period of 16 months, 14 children with a clinical diagnosis of cholelithiasis, ranging in age from 4 to 15 years (mean 12.2), were treated. All had symptoms of abdominal pain or vomiting; one had jaundice and recurrent cholecystitis. Five children (35%) had associated metabolic or hemolytic diseases. The 14 children were operated on using the laparoscopic cholecystectomy technique. No operation was converted to open cholecystectomy, but two patients required laparotomy: one because of suspected injury to the common duct, and the other because of non visualization of the gallbladder during laparoscopy. The mean post-operative hospital stay for the 11 children who underwent only laparoscopic cholecystectomy (one patient also had a simple mastectomy) was 50 hours (range 48–72 hours). All children resumed their normal activities almost immediately after discharge from hospital. No long-term biliary or other complications were seen in any patient throughout an average follow-up period of 6.2 months (range 3–16 months). The benefits of this operation in children are obvious: It is safe, effective, and well tolerated. La cholécystectomie celioscopique a pratiquement remplacé la cholécystectomie traditionnelle dans le traitement de la lithiase vésiculaire et de la cholécystite chez l'adulte. Pendant une période de 16 mois, nous avons traité par voie celioscopique 14 enfants âgés de 4 à 15 ans (âge moyen = 12.2 ans) pour une lithiase vésiculaire. Tous avaient des douleurs abdominales ou des vomissements. Un enfant avait un ictère associé à une cholécystite récidivante. Cinq enfants (35%) avaient des troubles métaboliques ou hémolytiques. Des 14 cas, deux laparotomies ont été nécessaires, une en raison d'un doute sur une plaie de la voie biliaire principale, l'autre parce que la vésicule n'a pu être visualisée. La durée moyenne de séjour pour les 11 enfants qui n'ont eu qu'une cholécystectomie (y compris un enfant qui a eu une mastectomie simple associée) a été de 50 heures (extrêmes: 48 à 72). Tous les enfants ont repris une activité pratiquement normale presqu'immédiatement après la sortie. Il n'y a eu aucune complication biliaire avec un suivi moyen de 6.2 mois (extrêmes 3–16 mois). Les avantages de cette intervention chez l'enfant sont évidents: sécurité, efficacité et bonne tolérance. La colecistectomía laparoscópica está reemplazando con rapidez a la colecistectomía tradicional, como la forma estándar de tratamiento para la colelitiasis y colecistitis en los adultos. En un período de 16 meses fueron tratados 14 niños con edades entre 4 y 15 años (media 12.2) con el diagnóstico clínico de colelitiasis. Todos presentaban sintomatología de dolor abdominal y vómito; uno presentaba ictericia y colecistitis recidivante; cinco (35%) sufrían enfermedades metabólicas o hemolíticas asociadas. Los 14 niños fueron intervenidos utilizando la técnica de colecistectomía laparoscópica. Ninguno requirió conversión a colecistectomía abierta, pero dos requirieron laparotomía—uno por sospecha de lesión del canal colédoco y otro por no visualización de la vesícula biliar en el curso de la laparoscopia. El promedio de la hospitalización para los 11 niños que tuvieron la colecistectomia laparoscópica solamente (un paciente también fue sometido a mastectomía simple) fue de 50 horas (rango 48–72 h); todos reasumieron sus actividades normales casi de inmediato a su egreso del hospital. No se registraron complicaciones biliares ni de otro tipo en un seguimiento promedio de 6.2 meses (rango 3–16 meses). Los beneficios de esta intervención en los niños son obvios; la operación es segura, efectiva y bien tolerada.

Molecular and Cellular Endocrinology, 2008

Langerhans cells (LC) are immune cells altered by exposure to ultraviolet radiation (UVB), a powe... more Langerhans cells (LC) are immune cells altered by exposure to ultraviolet radiation (UVB), a powerful stressor resulting in immune suppression. Prolactin (PRL) has been characterized as an immunomodulator, particularly during stress. In this study, we have asked whether separate administration of the two major forms of prolactin, unmodified and phosphorylated, to groups of 15 mice (3 experiments, each with 5 mice per treatment group) affected the number and morphology of these epidermal immune cells under control conditions, and following UV irradiation. Under control conditions, both PRLs reduced the number of γδ T, but a molecular mimic of phosphorylated PRL (S179D PRL) was more effective, resulting in a 30% reduction. In the irradiated group, however, S179D PRL was protective against a UV-induced reduction in γδ T number and change in morphology (halved the reduction and normalized the morphology). In addition, S179D PRL, but not unmodified (U-PRL), maintained a normal LC: γδ T ratio and sustained the dendritic morphology of LC after UV exposure. These findings suggest that S179D PRL may have an overall protective effect, countering UV-induced cellular alterations in the epidermis.

Microbial Ecology, 2011

Marine environment habitats, such as the coral mucus layer, are abundant in nutrients and rich wi... more Marine environment habitats, such as the coral mucus layer, are abundant in nutrients and rich with diverse populations of microorganisms. Since interactions among microorganisms found in coral mucus can be either mutualistic or competitive, understanding quorum sensing-based acyl homoserine lactone (AHL) language may shed light on the interaction between coral-associated microbial communities in the native host. More than 100 bacterial isolates obtained from different coral species were screened for their ability to produce AHL. When screening the isolated coral bacteria for AHL induction activity using the reporter strains Escherichia coli K802NR-pSB1075 and Agrobacterium tumefaciens KYC55, we found that approximately 30% of the isolates tested positive. Thin layer chromatography separation of supernatant extracts revealed different AHL profiles, with detection of at least one active compound in the supernatant of those bacterial extracts being able to induce AHL activity in the two different bioreporter strains. The active extract of bacterial isolate 3AT 1-10-4 was subjected to further analysis by preparative thin layer chromatography and liquid chromatography tandem mass spectrometry. One of the compounds was found to correspond with N-(3-hydroxydecanoyl)-l-homoserine lactone. 16S rRNA gene sequencing of the isolates with positive AHL activity affiliated them with the Vibrio genus. Understanding the ecological role of AHL in the coral environment and its regulatory circuits in the coral holobiont-associated microbial community will further expand our knowledge of such interactions.

Knowledge and Information Systems

The paper focuses on mining clusters that are characterized by a lagged relationship between the ... more The paper focuses on mining clusters that are characterized by a lagged relationship between the data objects. We call such clusters lagged co-clusters. A lagged co-cluster of a matrix is a submatrix determined by a subset of rows and their corresponding lag over a subset of columns. Extracting such subsets may reveal an underlying governing regulatory mechanism. Such a regulatory mechanism is quite common in real-life settings. It appears in a variety of fields: meteorology, seismic activity, stock market behavior, neuronal brain activity, river flow, and navigation, but a limited list of examples. Mining such lagged co-clusters not only helps in understanding the relationship between objects in the domain, but assists in forecasting their future behavior. For most interesting variants of this problem, finding an optimal lagged co-cluster is NP-complete problem. We present a polynomial-time Monte-Carlo algorithm for mining lagged co-clusters. We prove that, with fixed probability, the algorithm mines a lagged co-cluster which encompasses the optimal lagged co-cluster by a maximum 2 ratio columns overhead and completely no rows overhead. Moreover, the algorithm handles noise, anti-correlations, missing values, and overlapping patterns. The algorithm is extensively evaluated using both artificial and real-world test environments. The first enable the evaluation of specific, isolated properties of the algorithm. The latter (river flow and topographic data) enable the evaluation of the algorithm to efficiently mine relevant and coherent lagged co-clusters in environments that are temporal, i.e., time reading data and non-temporal.

Neuroscience Letters, 2000

The effects of serotoninergic stimulation on monoamines were studied in the heterozygous Lurcher ... more The effects of serotoninergic stimulation on monoamines were studied in the heterozygous Lurcher (Lc/1) mutant mouse, a model of human cerebellar ataxia. Wild type (1/1) and Lc/1 mice were treated for 40 days with L-tryptophan or buspirone, and serotonin (5-HT), dopamine (DA), noradrenaline (NA) and their main metabolites were measured in the cerebellum. In 1/1 mice, only buspirone increased concentrations of 5-HT metabolites. In the hypoplastic Lc/1 cerebellum, indoleamines were higher, and increased further after both treatments. The 5-HT turnover index was increased in 1/1 mice by buspirone, while in Lc/1 mutants it increased after L-tryptophan but was decreased by buspirone, indicating that in the mutants nerve terminals synthesize and accumulate 5-HT, but may not utilize it ef®ciently. Catecholamine contents remained unchanged in 1/1 mice, but in Lc/1 mutants with higher endogenous NA, L-tryptophan further increased NA and 3,4-dihydroxy-phenylacetic acid (DOPAC), and buspirone augmented NA, DA and DOPAC levels. q

Calcified Tissue International, 1982

Chicks were depleted of vitamin D, divided into groups, and treated daily with (a) cholecalcifero... more Chicks were depleted of vitamin D, divided into groups, and treated daily with (a) cholecalciferol, (b) 1α-hydroxycholecalciferol [1α(OH)-D3], (c) 24R, 25-dihydroxycholecalciferol [24R,25-(OH)2D3], or (d) 1α(OH)D3 and 24R,25(OH)2D3. Two additional groups of chicks were studied, one that was continuously depleted of vitamin D, and another that was continuously supplemented with the vitamin, since day 1. After killing, the tibiae were removed and tested for their mechanical properties. Bending load was applied to the midshaft, and the intrinsic properties of this site, its quantity and geometry were analyzed. From a mechanical point of view, the weakest bones found were of birds depleted of vitamin D, whereas the strongest were of those treated with 1α(OH)D3. Only the bones of the 24R,25(OH)2D3-treated or the 1α(OH)D3 and 24R,25(OH)2D3-treated groups of birds showed mechanical properties comparable to those obtained with vitamin D-replete chicks.

Journal in Computer Virology, 2010

This research proposes a novel automatic method (termed Auto-Sign) for extracting unique signatur... more This research proposes a novel automatic method (termed Auto-Sign) for extracting unique signatures of malware executables to be used by high-speed malware filtering devices based on deep-packet inspection and operating in real-time. Contrary to extant string and token-based signature generation methods, we implemented Auto-Sign an automatic signature generation method that can be used on large-size malware by disregarding signature candidates which appear in benign executables. Results from experimental evaluation of the proposed method suggest that picking a collection of executables which closely represents commonly used code, plays a key role in achieving highly specific signatures which yield low false positives.

Analytical and Bioanalytical Chemistry

This work evaluates the suitability of sorptive microextraction, using disposable silicone sorben... more This work evaluates the suitability of sorptive microextraction, using disposable silicone sorbents, and liquid chromatography time-of-flight mass spectrometry (LC-TOF-MS) for the determination of 15 fungicides in wine. Under optimized conditions, wine samples (10 mL) were diluted with the same volume of ultrapure water and poured in a glass vessel containing a magnetic stirrer and 4 g of sodium chloride. Extractions were performed at room temperature for 4 h, using an inexpensive silicone disk (12 μL volume) exposed directly to the sample. Thereafter, analytes were recovered with 0.2 mL of acetonitrile. The electrospray ionization (ESI) source was operated in the fast polarity switching mode obtaining, in the same injection, selective LC-MS records (extracted with a mass window of 10 ppm) of compounds rendering [M + H]+ and [M-H]− ions. The method provided limits of quantification (LOQs) between 0.1 and 2.2 ng mL−1, linear response ranges up to 500 ng mL−1, relative recoveries from 75% to 117% and an inter-day variability below 15% for all analytes in red and white wine samples. The feasibility of in situ sample enrichment followed by delayed desorption and analysis is also assessed.

Brazilian Journal of Poultry Science, 2004

This study was carried out at Faculdade de Medicina Veterinária e Zootecnia, UNESP, Botucatu-SP, ... more This study was carried out at Faculdade de Medicina Veterinária e Zootecnia, UNESP, Botucatu-SP, Brazil. The aim was to establish the normal values of bone mineral density (BMD) expressed in millimeters of aluminum in the tibia of broiler chickens using optical densitometry of radiographs. Four hundred Cobb male chicks were reared from 1 to 40 days of age, when 40 of them were selected and the right femurtibia articulation was radiographed. Radiographs were taken with the X-ray equipment calibrated for 45 kvp and 3.2 mAs and a focus-to-film distance of 90 cm. An aluminum phantom ASTM-6063 consisting of 20 ladder steps with graduate density was placed parallel to the area to be radiographed and used as a densitometry reference standard. Radiograph images were analyzed using the software ATHENA SIA. The proximal growth plate of the right tibia epiphysis was used as the standard reading region. The inclination axis of the reading window was 0 and the window was 10 mm high and 40-45 mm wide, depending on the bone size. Optical densitometry values of the radiographs ranged from 1.46 to 1.77 mmAl, and the coefficient of variation was 9.93%. It was concluded that densitometry values beyond the range established in the present study might indicate the presence of bone alteration in the tibia of broilers.

Journal of Plant Growth Regulation, 1996

Imidazole fungicides such as imazalil, prochloraz, and triflurnizole and the triazole growth reta... more Imidazole fungicides such as imazalil, prochloraz, and triflurnizole and the triazole growth retardant paclobutrazol promote the shoot-inducing effect of exogenous cytokinins in Araceae, such as Spathiphyllum floribundum Schott and Anthurium andreanum Schott. The mechanism of their action could partially be based on the inhibition of gibberellic acid (GA) biosynthesis, because administration of GA3 inhibits the phenomenon completely in S. floribundum. Not only is the suppression of GA biosynthesis involved, but also the metabolism of endogenous cytokinins is significantly altered. Although the balance between isopentenyladenine, zeatin, dihydrozeatin, and their derivatives was shifted to distinguished directions by administration of BA and/or imazalil and/or GA3, no correlation between these changes in metabolic pathways and the number of shoots could be found. The metabolism of BA was not significantly altered by adding imazalil to the micropropagation medium of S. floribundum.

Environmental Microbiology, 2009

In Synechocystis sp. strain PCC 6803, over 450 genes are upregulated following transfer of the ce... more In Synechocystis sp. strain PCC 6803, over 450 genes are upregulated following transfer of the cells from a high (1-5% CO2 in air, HC) to a low level of CO2 (as in air or lower, LC). This includes sbtA, ndhF3 and cmpA involved in inorganic carbon (Ci) uptake. Earlier studies implicated NdhR in the regulation of LCinduced genes but there are indications that additional components are involved. Following extraction of proteins from cells grown under HC and (NH4)2SO4 fractionation, we have identified LexA and two AbrBlike proteins, Sll0359 and Sll0822, which bind to a fragment of the sbtA promoter. Using extracts prepared from LC-grown cells, Sll0822 did not bind to the sbtA promoter despite its presence in the cells, suggesting that it may serve as a repressor of LC-induced genes. This is supported by the fact that sbtA, ndhF3 and cmpA normally expressed only under LC in the wild-type are transcribed under both HC and LC in a Dsll0822 mutant. When grown under HC this mutant exhibits an elevated apparent photosynthetic affinity to Ci, typically observed in the wild-type only under LC. Clearly, expression of genes essential for Ci uptake was sufficient to raise the apparent photosynthetic affinity for external Ci.

Journal of Physics D-applied Physics, 2010

In this paper we describe a method for evaluating the usability of web-based applications. Our me... more In this paper we describe a method for evaluating the usability of web-based applications. Our method is based on remote and automatic capture and semi-automatic analysis of users behavior, in order to find usability problems in the applications' interfaces. The goal of our method is to allow an analysis of the way users actually interact with the evaluated interface. Through the analysis of users behavior is possible to find patterns of interaction. Analyzing the patterns found and comparing it to the expected behavior for the tasks performed by users, we can detect usability problems. In this paper we also briefly describe a first experiment with our method and some initial results that point to the potential of the method in performing remote and automatic usability evaluations.

Pflugers Archiv-european Journal of Physiology, 1987

Using the patch-clamp technique,whole-cell recordings from solitary rat retinal ganglion cells in... more Using the patch-clamp technique,whole-cell recordings from solitary rat retinal ganglion cells in culture have established the nicotinic nature of the acetylcholine responses in these central neurons. Currents produced by acetylcholine (5–20 μmol/l) or nicotine (5–20 μmol/l) reversed in polarity near −5 mV and were unaffected by atropine (10 μmol/l). Agonist-induced currents were blocked by low doses(2–10 μmol/l) of the classical ‘ganglionic’ antagonists hexamethonium and mecamylamine, as well as by d-tubocurarine and dihydro-β-erythroidine (the latter two do not discriminate clearly between ganglionic and neuromuscular junction receptors). Treatment with the potent neuromuscular blocking agent α-bungarotoxin (10 μmol/l) did not affect the cholinergic responses of these cells, while toxin F (0.2 μmol/l), a neural nicotinic receptor antagonist, readily abolished acetylcholine-induced currents. Thus, the experiments performed to date show that the nicotinic responses of retinal ganglion cells in the central nervous system share the pharmacology of autonomic ganglion cells in the peripheral nervous system. The ionic current carried by the nicotinic channels was selective for cations, similar to that described for nicotinic channels in other tissues. In addition, single-channel currents elicited by acetylcholine were observed in whole-cell recordings with seals > 5 GΩ as well as in occasional outside-out patches of membrane. These acetylcholine-activated events, which had a unitary conductance of 48 pS and a reversal potential of 0 mV, represent the ion channels that mediate the neural nicotinic responses observed in these experiments on retinal ganglion cells.

Journal of Chromatography A, 2011

In this work, a reliable and selective procedure for the determination of thirteen fungicides in ... more In this work, a reliable and selective procedure for the determination of thirteen fungicides in red and white wine samples is proposed. Solid-phase extraction (SPE) and liquid chromatography (LC) tandem mass spectrometry (MS/MS), based on a hybrid quadrupole time-of-flight (QTOF) system, were used as sample preparation and determination techniques, respectively. Extraction and purification of target analytes was carried out simultaneously by using a reversed-phase Oasis HLB (200 mg) SPE cartridge combined with acetonitrile as elution solvent. Fungicides were determined operating the electrospray source in the positive ionization mode, with MS/MS conditions adjusted to obtain at least two intense product ions per compound, or registering two transitions per species when a single product was noticed. High selective MS/MS chromatograms were extracted using a mass window of 20 ppms for each product ion. Considering external calibration as quantification technique, the overall recoveries (accuracy) of the procedure ranged between 81% and 114% for red and white wine samples (10-20 mL), spiked at different concentrations between 5 and 100 ng mL −1 . Relative standard deviations of the above data stayed below 12% and the limits of quantification (LOQs) of the method, calculated for 10 mL of wine, varied between 0.1 ng mL −1 for cyprodinil (CYP) and 0.7 ng mL −1 for myclobutanil (MYC). The optimized method was applied to seventeen commercial wines produced in Spain and obtained from local supermarkets. Nine fungicides were determined, at levels above the LOQs of the method, in the above samples. The maximum concentrations and the highest occurrence frequencies corresponded to metalaxyl (MET) and iprovalicarb (IPR).

Brazilian Journal of Poultry Science, 2008

An experiment was carried out to establish mean bone quality values of the tibiae and femora of o... more An experiment was carried out to establish mean bone quality values of the tibiae and femora of ostriches and to evaluate these bones. The right leg bones of 10 males and 10 female African Black ostriches were evaluated. Birds were radiographed immediately after slaughter (during bleeding), with the aid of a portable X-ray apparatus. The obtained radiographs were scanned and bone mineral density means were obtained using software. Bone strength, Seedor index, and dry matter percentage were evaluated and correlated to weight gain during the finishing period (3-13 months of age). Mean values of the evaluated bone quality traits, not previously found in literature, were established. There were no significant differences between males and females in performance or bone quality parameters. It was concluded that male and female ostriches present similar performance and bone quality at slaughter age.

Astrophysical Journal, 2008

We study the superorbital modulation present in the Cygnus X-1 X-ray data, usually attributed to ... more We study the superorbital modulation present in the Cygnus X-1 X-ray data, usually attributed to the precession of the accretion disk and relativistic jets. We find a new, strong, 326 +/- 2 day period modulation starting in 2005, in Swift BAT and RXTE ASM light curves (LCs). We also investigate Vela 5B ASM and Ariel 5 ASM archival data and confirm the previously reported ~290 day periodic modulation, therefore confirming that the superorbital period is not constant. Finally, we study RXTE ASM LC before 2005 and find that the previously reported ~150 day period is most likely an artifact due to the use of a Fourier-power-based analysis under the assumption that the modulation has a constant period along the whole data sample. Instead, we find strong indications of several discrete changes of the precession period, happening in coincidence with soft and failed state transition episodes. We also find a hint of correlation between the period and the amplitude of the modulation. The detection of gamma rays above 100 GeV with MAGIC in 2006 September happened in coincidence with a maximum of the superorbital modulation. The next maximum will happen between 2008 July 2 and 14, when the observational conditions of Cygnus X-1 with ground-based Cerenkov telescopes, such as MAGIC and VERITAS, are optimal.

Brazilian Journal of Poultry Science, 2006

This study was carried out at Faculdade de Medicina VeterinÆria e Zootecnia, Universidade Estadua... more This study was carried out at Faculdade de Medicina VeterinÆria e Zootecnia, Universidade Estadual Paulista, Botucatu, SP, Brazil, and evaluated bone quality in broiler breeders. Twenty-three families of Ross broiler breeders were housed in 5.0-m† pens. The families were comprised of 13 females and one male at the onset of the experimental period. The mean number of females per family