Ciencia y Tecnología
Influence of residual milk-clotting enzyme and proteolysis on melting properties of soft cheese
Candioti, Mario César; Alonso, María Jimena; Hynes, Erica Rut
In this work, we assessed the influence of coagulant residual activity and primary proteolysis on Cremoso Argentino cheese melting properties. For that purpose, we made Cremoso soft cheeses using different amounts of coagulant, and also obtained samples in which milk clotting enzyme was inactivated. The residual activity of coagulant correlated with primary proteolysis, especially in early stages of ripening. Caseins’ hydrolysis did not significantly impact on the melting ability of the cheeses, expressed as the area increase after heating samples under standardised conditions. Samples with similar proximate composition showed some changes in meltability; those seemed related to pH evolution during ripening.
Protective action of Lactobacillus kefir carrying S-layer protein against Salmonella enterica serovar Enteritidis
Protective action of Lactobacillus kefir carrying S-layer protein against Salmonella enterica serovar Enteritidis
Golowczyc, Marina Alejandra; Mobili, Pablo; Garrote, Graciela Liliana; Abraham, Analia Graciela; de Antoni, Graciela Liliana
Eight Lactobacillus kefir strains isolated from different kefir grains were tested for their ability to antagonize Salmonella enterica serovar Enteritidis (Salmonella enteritidis) interaction with epithelial cells. L. kefir surface properties such as autoaggregation and coaggregation with Salmonella and adhesion to Caco-2/TC-7 cells were evaluated. L. kefir strains showed significantly different adhesion capacities, six strains were able to autoaggregate and four strains coaggregated with Salmonella. Coincubation of Salmonella with coaggregating L. kefir strains significantly decreased its capacity to adhere to and to invade Caco-2/TC-7 cells. This was not observed with non coaggregating L. kefir strains. Spent culture supernatants of L. kefir contain significant amounts of S-layer proteins. Salmonella pretreated with spent culture supernatants (pH 4.5–4.7) from all tested L. kefir strains showed a significant decrease in association and invasion to Caco-2/TC-7 cells. Artificially acidified MRS containing lactic acid to a final concentration and pH equivalent to lactobacilli spent culture supernatants did not show any protective action. Pretreatment of this pathogen with spent culture supernatants reduced microvilli disorganization produced by Salmonella. In addition, Salmonella pretreated with S-layer proteins extracted from coaggregating and non coaggregating L. kefir strains were unable to invade Caco-2/TC-7 cells. After treatment, L. kefir S-layer protein was detected associated with Salmonella, suggesting a protective role of this protein on association and invasion.
Implementing a post-graduate degree course for diabetes educators in Argentina.
Implementing a post-graduate degree course for diabetes educators in Argentina.
Gagliardino, Juan Jose; Malbran, Maria del Carmen; Clark, Charles
One reason for poor diabetes outcomes – the development of disabling, potentially life-threatening complications – is the lack of effective participation by people with diabetes in the management of their own condition. This participation is the key to successfully achieving therapeutic goals. To be able to follow a difficult and complex life-long regimen requires high levels of motivation and knowledge. Yet although extensive evidence supports this concept, only a minority of people receive appropriate diabetes education. Thus, many people with diabetes are handicapped in their self-care by limited knowledge and skills. The authors describe an initiative in La Plata, Argentina, which aims to promote and diffuse high-quality diabetes education by training healthcare providers to become expert educators.
The diabetes-related attitudes of health care professionals and persons with diabetes in Argentina
The diabetes-related attitudes of health care professionals and persons with diabetes in Argentina; Actitudes relacionadas con la diabetes en los profesionales sanitarios y las personas con diabetes en Argentina
Gagliardino, Juan Jose; González, Claudio; Caporale, Joaquín E.
To test diabetes-related attitudes of health care team members (HCTMs) and people with diabetes in a developing country, in this case, Argentina.
The third version of the Diabetes Attitudes Scale (DAS-3) was randomly administered, in person, to 252 HCTMs (nurses, nutritionists, physicians, podiatrists, and social workers) and 279 people with type 1 or type 2 diabetes mellitus in several provinces of Argentina in 2004. Data from 531 completed questionnaires were included in the study. The data were statistically analyzed using analysis of variance, covariance, chi-square, and t-tests.; Analizar las actitudes relacionadas con la diabetes en los miembros del equipo de salud (MES) y las personas con diabetes en un país en desarrollo, Argentina. Se administró de forma aleatoria la tercera versión de la Escala de Actitudes en la Diabetes (DAS-3) a 252 MES (enfermeros, nutriólogos, médicos, podólogos y trabajadores sociales) y a 279 personas con diabetes mellitus tipos 1 ó 2 en varias provincias de Argentina en 2004. Los datos de 531 cuestionarios respondidos se evaluaron mediante análisis de varianza y covarianza, y las pruebas de la t y de la ji al cuadrado.
Caracterización de la proteína microtubular de diferentes helmintos parásitos: Sus implicancias en el modo de acción de los benzimidazoles antihelmínticos
Caracterización de la proteína microtubular de diferentes helmintos parásitos: Sus implicancias en el modo de acción de los benzimidazoles antihelmínticos
Scarcella, Silvana Andrea; Ceriani, Maria Carolina; Rodriguez, Julio Armando; Solana, Hugo Daniel
Los antihelmínticos benzimidazoles (BZD) desestabilizan el equilibrio tubulina-microtúbulo originando en el parásito una pérdida de la homeostasis celular, desprendimiento y muerte. Su baja toxicidad se explica por una mayor afinidad por la tubulina del parásito, especialmente en cestodes y nematodes, comparada con la observada para tubulina de mamífero. Al ser tubulina una proteína altamente conservada en la escala zoológica se hace necesario investigar las probables causas de esa diferente afinidad. El objetivo del presente trabajo fue comparar ciertas características moleculares de tubulina de trematodes (Fasciola hepatica), cestodes (Moniezia expansa), nematodes (Ascaris suum) y tubulina purificada de cerebro de rata. Se utilizaron técnicas electroforéticas (PAGE) e inmunoquímicas con anticuerpos monoclonales específicos dirigidos contra a y b tubulina. Los resultados demostraron que aunque en diferente cuantía mientras que fue factible la detección de las diferentes tubulinas en mamíferos, cestodes y nematodes, en ninguno de los casos se detectó la tubulina de F. hepatica. Esto tiene implicancias directas en el entendimiento de las diferentes susceptibilidades de cada especie a estos fármacos, lo cual puede ser un primer paso hacia la comprensión de la actividad farmacológica de estas drogas.; The anthelmintic benzimidazoles cause a destabilization of tubulin-microtubule equilibrium which induces to a lost of the cellular homeostasis, detaching and death of the parasite. They have a low toxicity on the infested animal, explained as a higher affinity for the parasite tubulin, mainly that of cestodes and nematodes. From an evolutionary point of view, tubulin is a highly conserved protein, thus in order to understand the probable causes for that difference in affinity, it is necessary to further investigate the microtubular protein at a molecular level. The aim of this project was to compare certain molecular characteristics of tubulin from trematodes (Fasciola hepatica), cestodes (Moniezia expansa), nematodes (Ascaris suum) and purified rat brain tubulin. For this purpose electrophoretic techniques (PAGE) followed by immunochemistry using specific monoclonal antibodies against α and β tubulin were used. Results showed that it was possible to detect tubulin spots, but not in the same amount, in mammals, cestodes and nematodes. Under our experimental conditions it was not possible to detect F. hepatica tubulin. This could help to understand the differences in the answer to the anthelmintic drugs and also to learn something about to the farmacological activity of these.
Dive depth and plumage air in wettable birds: the extraordinary case of the imperial cormorant
Dive depth and plumage air in wettable birds: the extraordinary case of the imperial cormorant
Quintana, Flavio Roberto; Wilson, Rory P.; Yorio, Pablo Martin
Cormorants are considered to be remarkably efficient divers and hunters. In part, this is due to their wettable plumage with little associated air, which allows them to dive with fewer energetic costs associated with buoyancy from air in the feathers. The literature attributes particularly exceptional diving capabilities to cormorants of the ‘blue-eyed’ taxon. We studied the diving behaviour of 14 male imperial cormorants Phalacrocorax atriceps (included in the blue-eyed taxon) in Patagonia, Argentina, and found that this species did indeed dive deeper, and for longer, than most other non-blue-eyed cormorant species. This species also exhibited longer dive durations for any depth as well as longer recovery periods at the surface for particular dive durations. We propose that this, coupled with atypically long foraging durations at sea in cold water, suggests that cormorants of
the blue-eyed complex have a plumage with a substantial layer of insulating air. This is given credence by a simple model. High volumes of plumage air lead to unusually high power requirements during foraging in shallow, warmer waters, which are conditions that tend to favour wettable plumage. However, deep dives and/or cold water should favour the blue-eyed phenotype, which
explains their essentially high latitude distribution.
Variability of UVR effects on photosynthesis of summer phytoplankton assemblages from a tropical coastal area of the South China Sea.
Variability of UVR effects on photosynthesis of summer phytoplankton assemblages from a tropical coastal area of the South China Sea.
Kunshan, Gao; Gang Li; Helbling, Eduardo Walter; Villafañe, Virginia Estela
From June to September 2005, we carried out experiments todetermine the ultraviolet radiation (UVR) -induced photoinhibitionof summer phytoplankton assemblages from a coastal site ofthe South China Sea. Variability in taxonomic composition wasdetermined throughout the summer, with a peak chlorophyll a(chl a20 lg chl a L)1) dominated by the diatom Skeletonemacostatum that was detected early in the study period; the rest ofthe time samples were characterized by monads and flagellates,with low chl a values (1–5 chl a lg L)1). Surface water sampleswere placed in quartz tubes, inoculated with radiocarbon andexposed to solar radiation for 2–3 h to determine photosyntheticrates under three quality radiation treatments (i.e. PAB, 280–700 nm; PA, 320–700 nm and P, 400–700 nm) using differentfilters and under seven levels of ambient irradiance using neutraldensity screens (P vs E curves). UVR inhibition of samplesexposed to maximum irradiance (i.e. at the surface) varied from)12.2% to 50%, while the daytime-integrated UVR-relatedphotoinhibition in surface seawater varied from )62% to 7%.The effects of UVR on the photosynthetic parameters PBmax andEk were also variable, but UV-B accounted for most of theobserved variability. During sunny days, photosynthesis ofmicroplankton (>20 lm) and piconanoplankton (<20 lm) weresignificantly inhibited by UVR (mostly by UV-B). However,during cloudy days, while piconanoplankton cells were stillinhibited by UVR, microplankton cells used UVR (mostlyUV-A) as the source of energy for photosynthesis, resulting inhigher carbon fixation in samples exposed to UVR than the onesexposed only to photosynthetically active radiation (PAR). Ourresults indicate that size structure and cloudiness clearlycondition the overall impact of UVR on phytoplankton photosynthesisin this tropical site of South China. In addition, modelpredictions for this area considering only PAR for primaryproduction might have underestimated carbon fixation due toUVR contribution.
Deep divers in shallow seas: Southern elephant seals on the Patagonian shelf
Deep divers in shallow seas: Southern elephant seals on the Patagonian shelf
Campagna, Claudio; Piola, Alberto Ricardo; Marin, Maria Rosa; Lewis, Mirtha Noemi; Zajaczkovski, Uriel; Fernandez, Teresita Josefa
Elephant seals are wide-ranging, pelagic, deep-diving (average of 400–600 m) predators that typically travel to open waters and continental shelf edges thousands of kilometers from their land breeding colonies. We report a less common pattern of foraging in the shallow waters of a continental shelf. Southern elephant seals, Mirounga leonina, that breed at Penı´nsula Valde´s (Argentina), face an extended (1,000,000km2; 400–700 km-wide, depending on track), shallow (o150 m) and seasonally productive plateau, the Patagonian shelf. Adults of both sexes usually cross it in rapid transit to other potential foraging grounds on the shelf edge or in the Argentine Basin, but 2–4 year-old juveniles spread over the plateau and spent months in shallow waters. This behavior was recorded for 9 seals (5 males and 4 females) of 23 satellitetrackedjuveniles (springs of 2004 and 2005) and for 2 subadult males studied in previous seasons. Trips included travel trajectories and time spent in areas where swim speed decreased, suggesting foraging. Preferred locations of juvenile females were in the proximity of the shelf break, where stratified waters had relatively high phytoplankton concentrations, but young and subadult males used the relatively cold (7–8 1C), low-salinity (33.3) mid-shelf waters, with depths of 105–120m and a poorly stratified water column. Three of the latter seals, instrumented with ime–depth recorders, showed dives compatible with benthic feeding and no diel pattern of depths distribution. Regions of the mid-shelf were used in different seasons and were associated with low chlorophyll-a concentration at the time of the visit, suggesting that surface productivity does not overlap with putative quality habitat for benthic foragers. Benthic diving on the shallow mid-shelf would be a resource partitioning strategy advantageous for young males prior to greater energetic demands of a high growth rate and a large body size. Later in life, the more predictable, bathymetry-forced, shelf-break front may offer the food resources that explain the uninterrupted increase of this population over several decades.
Comparisons of IRI TEC predictions with GPS and digisonde measurements at Ebro
Comparisons of IRI TEC predictions with GPS and digisonde measurements at Ebro
Mosert, Marta Estela; Gende, Mauricio Alfredo; Brunini, Claudio Antonio; Ezquer, Rodolfo Gerardo; Altadill, D.
Vertical TEC measurements obtained with GPS satellite signals (GPSTEC) and total electron content derived from ionograms (ITEC) are compared with the latest version of the International Reference Ionosphere, IRI-2000 (IRITEC). Digisonde data from the Ebro station (40.8°N, 0.5°E) recorded during two years of high solar activity 2000 (Rz 12 = 117) and 2001 (Rz 12 = 111) are used in the study. The results obtained with the three techniques are similar, and as expected, the GPS TEC values are greater than those obtained with the digisonde measurements. The IRI predictions generally overestimate the ITEC values. The diurnal and seasonal variations of the plasmaspheric electron content are also analyzed.
Ionospheric variability studies in Argentina
Ionospheric variability studies in Argentina
Ezquer, Rodolfo Gerardo; Mosert, Marta Estela
This paper reviews and extends studies on ionospheric variability performed by the Argentine scientific community. Ground based ionosonde measurements for different seasonal and solar conditions and vertical total electron content (VTEC) obtained with GPS satellite signals during a high solar activity year are used. Median, quartiles and deciles are used to specify the variability. In general, the results show that: (a) the variability is higher in low solar activity than in high solar activity, and (b) it is larger by night than by day. Moreover, is shown that could be possible specify the variability of foF2 for high solar activity and hours around noon.
Leafminer parasitoids and pest management. Literature review.
Leafminer parasitoids and pest management. Literature review.
Salvo, Silvia Adriana; Valladares, Graciela Rosa
Leafminers are insects whose larvae live and feed within plant leaves, consuming mesophyll tissue without damaging the leaf epidermis. Several species are considered serious pests on intensive, horticultural, and ornamental crops. Natural enemies are the most frequent source of mortality for this herbivore insect guild, with parasitoids being the most effective and best represented source. This article provides an updated summary of the available research on leafminer parasitoids in relation to pest management. Parasitoids of leafminers are predominantly generalists, and can thus rapidly include in their host ranges newly introduced leafminer species, frequently achieving effective regulation a few years after the pest becomes established. Classical and augmentative biological control strategies are broadly used for leafminer pest management. Several studies have dealt with the simultaneous use of parasitoids together with chemical and cultural control. Many conventional insecticides have detrimental effects on parasitoids; however, others could be compatible with biological control. Although integrated pest management programs employing a combination of several control strategies have achieved success against leafminer pests, the effects of cultural practices that could boost parasitoid populations have been scarcely studied
Los indígenas de la Patagonia en los libros de texto de la Congregación Salesiana: La construcción de otros internos (1900-1930)
Los indígenas de la Patagonia en los libros de texto de la Congregación Salesiana: La construcción de otros internos (1900-1930)
Nicoletti, Maria Andrea
Nos proponemos analizar la formación de los “otros internos” en los indígenas de la Patagonia, como una construcción en tensión entre mecanismos de particularización y de universalización, a través de un corpus de libros de texto de la Congregación salesiana, entre fines del siglo XIX y principios del siglo XX. Este análisis distingue básicamente tres categorizaciones: la construcción del “indio infiel”, la conceptualización del indígena como “salvaje” pero “salvaje redimido”, y el estereotipo del tehuelche como “indio de la Patagonia”. La primera parte de la fundamentación misionera “ad gentes” del fundador de la Congregación, Don Bosco. La segunda surge del contexto de la conquista al “desierto”, y la tercera de un estereotipo que analizamos desde las fotografías. En este último caso, el prototipo del “indio de la Patagonia” es el tehuelche y no el mapuche, en función de la identificación del mapuche con el “araucano invasor” y de la imagen de la docilidad tehuelche en la tarea evangelizadora. Los textos salesianos repiten los conceptos etnocentristas y los estereotipos de salvajismo sobre los indígenas patagónicos que aparecen en los textos oficiales, pero introducen, fieles a su pertenencia a la Iglesia, temáticas que resignifican el concepto del “salvaje” como “infiel” y de la necesidad de “civilizar” con la de evangelizar.; We propose to analyze the formation of intern others in the natives of the Patagonia, as a construction in tension between mechanisms of particularization and of universalization, through the books of the Salesians between the late XIXth century and the early XXth century. We basically distinguish three categorizations: the construction of the unfaithful native, the conceptualization of the native as savage but redeemed savage, and the stereotype of the tehuelche as native of the Patagonia. The first is the missionary theory ad gentes by the founder of the Congregation, Don Bosco. The second emerges from the context of the conquest to the desert, and the third is a stereotype that we analyze from photography. Here, the prototype of the native of the Patagonia is the tehuelche and not the mapuche, due to the identification of the mapuche with the Araucanian invader, and to the image of the tehuelche docility towards evangelization. The Salesians manuals repeat the ethnocentric concepts and the stereotypes of savagery on the Patagonian natives who appear in the official books, but they introduce, loyal to the Church, issues which resignify the term savage as unfaithful and the need to civilize with evangelize.
The peer-Review process for Amercan Antiquity and Latin American Antiquity
The peer-Review process for Amercan Antiquity and Latin American Antiquity
Lanata, Jose Luis; Aldenderfer, Mark; Jochim, Michael
Far from being perfect, the peer-review process is nevertheless the most effective way to assure the quality of a publication. Because they have used peer review from their very beginnings, American Antiquity (AAQ) and Latin American Antiquity (LAQ) are journals of high academic impact with strong reputations in the world academic community. The peer-review process seeks not only to identify the highest-quality manuscripts, but also works to improve the clarity of presentation of any author. The process is based on four fundamental principles: the importance of the diffusion of knowledge, the assurance of the preservation of knowledge in different media, the maintenance of control over the quality of knowledge that is disseminated, and the proper crediting to investigators and their discoveries and scientific contributions. Taken together, these principles maintain the excellence of scientific knowledge in any field (Meadows 1974; Ravetz 1973; Ziman 1968).American Antiquity (AAQ) and Latin American Antiquity (LAQ) are journals of high academic impact with strong reputations in the world academic community. The peer-review process seeks not only to identify the highest-quality manuscripts, but also works to improve the clarity of presentation of any author. The process is based on four fundamental principles: the importance of the diffusion of knowledge, the assurance of the preservation of knowledge in different media, the maintenance of control over the quality of knowledge that is disseminated, and the proper crediting to investigators and their discoveries and scientific contributions. Taken together, these principles maintain the excellence of scientific knowledge in any field (Meadows 1974; Ravetz 1973; Ziman 1968).(LAQ) are journals of high academic impact with strong reputations in the world academic community. The peer-review process seeks not only to identify the highest-quality manuscripts, but also works to improve the clarity of presentation of any author. The process is based on four fundamental principles: the importance of the diffusion of knowledge, the assurance of the preservation of knowledge in different media, the maintenance of control over the quality of knowledge that is disseminated, and the proper crediting to investigators and their discoveries and scientific contributions. Taken together, these principles maintain the excellence of scientific knowledge in any field (Meadows 1974; Ravetz 1973; Ziman 1968).
Criterios y actividades para la evaluación del aprendizaje en cursos universitarios de química
Criterios y actividades para la evaluación del aprendizaje en cursos universitarios de química; Activities and criteria for the chemical learning evaluation in graduate courses
Wainmaier C.; Salinas, Julia Josefa; Viera, Lidia Mabel; Ramírez S.
Abstract In this paper we intend to make a contribution to the learning evaluation practice that may accompany those educative proposals whose objective is a comprehensive learning. We adopt a “constructivist” psychological perspective, an epistemological orientation of “scientific realism” and a methodological vision that “integrates quantitative and qualitative strategies”. From this perspective, some dimensions and sub-dimensions taken as learning evaluation criteria, as well as some learning evaluation activities, are proposed for chemical contents at an introductory university level in scientific and technological careers. These criteria, originally developed in educative research, are potentially highly transferable to classroom.
Effects of granule-associated protein PhaP on glycerol-dependent growth and polymer production in poly(3-hydroxybutyrate)-producing Escherichia coli
Effects of granule-associated protein PhaP on glycerol-dependent growth and polymer production in poly(3-hydroxybutyrate)-producing Escherichia coli
de Almeida, Alejandra; Nikel, Pablo Ivan; Giordano, Andrea Mariana; Pettinari, María Julia
Polyhydroxyalkanoates (PHAs) are accumulated as intracellular granules by many bacteria under unfavorable conditions, enhancing their fitness and stress resistance. Poly(3-hydroxybutyrate) (PHB) is the most widespread and best-known PHA. Apart from the genes that catalyze polymer biosynthesis, natural PHA producers have several genes for proteins involved in granule formation and/or with regulatory functions, such as phasins, that have been shown to affect polymer synthesis. This study evaluates the effect of PhaP, a phasin, on bacterial growth and PHB accumulation from glycerol in bioreactor cultures of recombinant Escherichia coli carrying phaBAC from Azotobacter sp. strain FA8. Cells expressing phaP grew more, and accumulated more PHB, both using glucose and using glycerol as carbon sources. When cultures were grown in a bioreactor using glycerol, PhaP-bearing cells produced more polymer (2.6 times) and more biomass (1.9 times) than did those without the phasin. The effect of this protein on growth promotion and polymer accumulation is expected to be even greater in high-density cultures, such as those used in the industrial production of the polymer. The recombinant strain presented in this work has been successfully used for the production of PHB from glycerol in bioreactor studies, allowing the production of 7.9 g/liter of the polymer in a semisynthetic medium in 48-h batch cultures. The development of bacterial strains that can efficiently use this substrate can help to make the industrial production of PHAs economically feasible.
La "conquista del desierto": desde perspectivas hegemónicas y subalternas
La "conquista del desierto": desde perspectivas hegemónicas y subalternas
Briones, Claudia Noemi; Delrio, Walter Mario
Este artículo discute algunas de las implicancias materiales y simbólicas del avance militar sobre Pampa y Patagonia desde dos amplios campos. Por un lado, ponderamos el lugar que la llamada “conquista del desierto” ha tenido en la territorialización del estado-nación y en la formación nacional de alteridad en Argentina, trabajando desde las memorias hegemónicas, el sentido común y las políticas públicas. Por el otro, introducimos memorias subalternas que exponen aspectos menos conocidos de las prácticas de disposición de los pueblos originarios, no sólo para explorar las reverberaciones de los procesos de construcción de la nación-como-estado en la diversificación de las trayectorias indígenas, sino también para ampliar los campos de visión que los discursos hegemónicos a menudo restringen. Sobre esta base argumentamos que la política indígena del estado argentino no ha estado meramente basada en “respuestas específicas a casos concretos”, ni operó espasmódicamente, como comúnmente se afirma. Sostenemos por el contrario que partió de promover un ejercicio sistemático, material y conceptual, de des-indianización y des-tribalización, buscando concretar a posteriori del período de conquista militar la imagen de un “desierto” necesitado de pioneros europeos.; This paper discusses some material and symbolic implications of the military annexation of Pampa and Patagonia, by setting the process against two broad frames of reference. On the one hand, we depart from hegemonic memories, common sense understandings and public policies, as to ponder the role of the so-called “conquest of the desert” in the territorialization of the nation-state and the configuration of Argentina’s formation of alterity. On the other, we introduce subaltern memories which expose less known aspects of state practices of indigenous disposal, not only to analyze the effects of state-building processes on the diversification of indigenous trajectories, but also to amplify fields of vision often restricted by hegemonic discourses. On this basis, we argue that Argentina’s Indigenous Policy has not been merely based upon “limited responses to concrete cases” nor operated in spasmodic or random terms, as it has been commonly contended. It has rather promoted a systematic exercise of de-indianization and de-tribalizacion, as to make real the image of a “desert” in need of European pioneers once the militarized period was over.
Genetic instability induced by low doses of x-rays in hamster cells
Genetic instability induced by low doses of x-rays in hamster cells
Seoane, Analia Isabel; Güerci, A.; Dulout, Fernando Noel
Purpose: Genomic instability involves time delayed events and can be manifested as elevated rates of heritable changes in the progeny of irradiated cells. To study the induction of chromosomal instability by very low doses of radiation Chinese Hamster Ovary (CHO) cells were exposed to 10 - 50 milisieverts (mSv) (≈10 - 50 miligrays (mGy)) of x-rays. Materials and methods: Control and irradiated cell populations were assayed for chromosomal aberrations and assessed using a micronucleus test and anaphase-telophase analysis at the first cell division post-irradiation and at every four population doublings thereafter up to 16 population doublings post-irradiation. Results: Frequencies of micronuclei, anaphase-telophase alterations and chromosomal aberrations were increased when the cells were analysed immediately after x-ray exposure. Micronuclei and anaphase-telophase alterations showed significantly increased frequencies when they were analysed at 12 and 16 population doublings after exposure to 50 mSv. Chromosomal aberrations increased significantly at 12 and 16 population doublings after exposure to 10 mSv and 50 mSv. Conclusions: Our results are consistent with the presence of a phenomenon by which the initial DNA damage in the surviving cells is memorized. Micronuclei and achromatic lessions were the main cytogenetic damage observed in cells exposed to very low doses of x-rays, indicating that these low doses are able to induce genetic instability. © 2007 Informa UK Ltd.
El mito de Fedra en el marco de los debates europeos entre modernización e identidad : D'Annunzio y Unamuno / Sandro Abate
El mito de Fedra en el marco de los debates europeos entre modernización e identidad : D'Annunzio y Unamuno / Sandro Abate
Abate, Sandro
Desde Eurípides y Séneca, sin olvidar a Racine y Garnier, el mito de Fedra ejerció una especial fascinación sobre el arte y renovó periódicamente su vigencia. La poética de grandes sectores artísticos de finales del siglo XIX, articulada por la remisión al código clasicista y por el apartamiento de toda forma de arte vulgar o burgués, produjo las dos últimas versiones de esta tragedia. la Fedra de Gabriele d’Annunzio (1909) y la Fedra de Miguel de Unamuno (1911), estrenadas en Milán y Madrid, respectivamente.
En su conjunto podría decirse que ambas producciones responden al renovado impulso clasicista que ha caracterizado a este segmento cultural que se extiende entre fines del siglo XIX y hasta la Primera Guerra Mundial. Pero a pesar de ello, las dos tragedias consideradas en particular divergen profundamente en los planteos preferenciales que formulan y en los intereses culturales y dramáticos que sus respectivos autores colocaron en escena. Sus respectivos marcos ideológicos –nietzscheano en un caso y cristiano en el otro- explican muchas de estas divergencias.
Reflexión acerca de ética e investigación psicológica
Reflexión acerca de ética e investigación psicológica
Richaud, Maria Cristina
Relevant ethical principles in research practice involving people include respect, benefits, and justice. When specifically applied to research projects, various essential topics stem from those principles, such as the informed consent of the people involved, risks and benefits, validity, data processing techniques, and verbal and non-verbal communication, among others. All this relates to the personal ethics of the researcher, which, when non-existent, turn most rules and regulations of no use, since they become ignored by someone who lacks an inner and earnest conviction about his or her expected actions. Knowing how to do ethical research leads to increasing our ability to obtain valid results, the needed co-operation of the people involved, and the essential social support that make up the supporting net of science.; Los principios éticos relevantes en la práctica de la investigación con personas son el respeto, el beneficio y la justicia; de los cuales se desprenden distintas temáticas fundamentales a la hora de investigar, como el consentimiento informado de los participantes, los riesgos y beneficios, la validez, el manejo de los datos, la comunicación verbal y no verbal, entre otras. Esto se remite a la ética personal del investigador, sin la cual pueden resultar inútiles muchas regulaciones y normativas al ser desoídas por quien no tiene la convicción íntima y sincera de cómo debería accionar. El saber realizar investigaciones en forma ética conduce a la habilidad para obtener resultados válidos, la cooperación necesaria de los participantes y el apoyo social necesario para sustentar la ciencia.
El teatro de la escritura : "Apariciones" de Margo Glantz
El teatro de la escritura : "Apariciones" de Margo Glantz
Perilli, Carmen Noemi
Margo Glantz apuesta a una literatura que, en curiosas ficciones, trabaja continuidades y fracturas con una mirada descentrada que busca poner en diálogo tradiciones desde un espacio de mujer. El imaginario literario y cultural de la nación moderna mexicana destacó, a lo largo del siglo XX, la virilidad como factor determinante. Glantz construye un lugar de mujer donde el cuerpo femenino hace bulto, se niega a ser transparente. La ficción histórica y el gesto genealógico le permiten inscribir narrativas distintas. En su obra se reconoce la presencia magistral de figuras como Alfonso Reyes. Invención y erudición sustentan densos itinerarios que no eluden la historia al armar la arqueología de un imaginario, que explora restos escriturarios y los usa como material creativo, insertándolos en nuevos sistemas significativos. Margo Glantz sostiene una fuerte relación con las instituciones centrales de la cultura mexicana: la Universidad Autónoma de México, la Academia Mexicana de la Lengua y el claustro de Sor Juana Inés de la Cruz. Su actuación dentro del campo intelectual ha recibido un amplio reconocimiento debido a su tarea filológica y crítica, en la que, de modo magistral y a veces discutido, ha definido momentos de la historia literaria. Podemos adscribirla a lo que, en su análisis de la narrativa mexicana, denominó literatura de la “escritura” por oposición a la literatura de la onda en una particular versión de la antigua polémica entre artepurismo y realismo.
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