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Showing papers by "University of Buenos Aires published in 2002"


Proceedings ArticleDOI
03 Jun 2002
TL;DR: An improved calculation of ferrite core loss for nonsinusoidal waveforms separates a flux trajectory into major and minor loops via a new recursive algorithm that is highly accurate and outperforms two previous methods for measured data.
Abstract: An improved calculation of ferrite core loss for nonsinusoidal waveforms separates a flux trajectory into major and minor loops via a new recursive algorithm. It is highly accurate and outperforms two previous methods for our measured data. The only characteristics of the material required are the standard Steinmetz-equation parameters.

935 citations


Journal ArticleDOI
TL;DR: In this article, the authors studied the orogenic effects of flat subduction in an active convergent margin in the Pampean segment of Argentina and Chile (27°00′ −33°30′S) and found that the main deformation phases and uplift of the thin and thick-skinned fold and thrust belts of the principal and frontal Cordilleras of the Sierras Pampeanas occurred between 20 and 8.6 Ma.

693 citations


Journal ArticleDOI
TL;DR: Recent literature showing the involvement of BDNF/TrkB signaling in hippocampal-dependent learning paradigms, as well as in the types of cellular plasticity proposed to underlie learning and memory are reviewed.
Abstract: One of the most rigorously investigated problems in modern neuroscience is to decipher the mechanisms by which experience-induced changes in the central nervous system are translated into behavioral acquisition, consolidation, retention, and subsequent recall of information. Brain-derived neurotrophic factor (BDNF) has recently emerged as one of the most potent molecular mediators of not only central synaptic plasticity, but also behavioral interactions between an organism and its environment. Recent experimental evidence indicates that BDNF modulates synaptic transmission and plasticity by acting across different spatial and temporal domains. BDNF signaling evokes both short- and long-term periods of enhanced synaptic physiology in both pre- and postsynaptic compartments of central synapses. Specifically, BDNF/TrkB signaling converges on the MAP kinase pathway to enhance excitatory synaptic transmission in vivo, as well as hippocampal-dependent learning in behaving animals. Emerging concepts of the intracellular signaling cascades involved in synaptic plasticity induced through environmental interactions resulting in behavioral learning further support the contention that BDNF/TrkB signaling plays a fundamental role in mediating enduring changes in central synaptic structure and function. Here we review recent literature showing the involvement of BDNF/TrkB signaling in hippocampal-dependent learning paradigms, as well as in the types of cellular plasticity proposed to underlie learning and memory.

674 citations


Journal ArticleDOI
TL;DR: The current wealth of new information promises a future scenario in which individual members of the galectin family or their ligands will be used as powerful anti-inflammatory mediators and selective modulators of the immune response.

549 citations


Journal ArticleDOI
TL;DR: The role of natural antioxidants derived from popular plants to reduce or prevent the oxidative stress in gastric ulcer induced by ethanol is considered.
Abstract: There is evidence concerning the participation of reactive oxygen species in the etiology and physiopathology of human diseases, such as neurodegenerative disorders, inflammation, viral infections, autoimmune pathologies, and digestive system disorders such as gastrointestinal inflammation and gastric ulcer. The role of these reactive oxygen species in several diseases and the potential antioxidant protective effect of natural compounds on affected tissues are topics of high current interest. To consider a natural compound or a drug as an antioxidant substance it is necessary to investigate its antioxidant properties in vitro and then to evaluate its antioxidant functions in biological systems. In this review article, we shall consider the role of natural antioxidants derived from popular plants to reduce or prevent the oxidative stress in gastric ulcer induced by ethanol.

532 citations


Journal ArticleDOI
TL;DR: Dimmer procyanidin dimer, (-)-epicatechin, and (+)-catechin were detected in the plasma of human subjects as early as 30 min after the consumption of a flavanol-rich food such as cocoa.

512 citations


Journal ArticleDOI
TL;DR: It is demonstrated that nitric oxide mediates the auxin response leading the adventitious root formation and a transient increase in NO concentration was shown to be required and to be part of the molecular events involved in adventitiousRoot development induced by indole acetic acid.
Abstract: In this report, we demonstrate that nitric oxide (NO) mediates the auxin response leading the adventitious root formation. A transient increase in NO concentration was shown to be required and to be part of the molecular events involved in adventitious root development induced by indole acetic acid

496 citations


Journal ArticleDOI
TL;DR: Oxygen radical formation was directly dependent on temperature-controlled respiration rates in states 3 and 4 and inversely related to mitochondrial coupling (RCR+) in state 4 and is therefore involved in cellular heat stress in this eurythermal marine ectotherm.
Abstract: SUMMARY Mitochondrial respiration, energetic coupling to phosphorylation and the production of reactive oxygen species (ROS) were studied in mitochondria isolated from the eurythermal bivalve Mya arenaria (Myoidea) from a low-shore intertidal population of the German Wadden Sea. Measurements were conducted both within the range of the habitat temperatures (5-15 °C) and when subjected to heat exposure at 20 °C and 25 °C. Experimental warming resulted in an increase in the rate of state 3 and state 4 respiration in isolated mitochondria. The highest respiratory coupling ratios (RCR) were found at 15 °C; at higher temperatures mitochondrial coupling decreased, and release of ROS doubled between 15 and 25 °C. ROS production was 2-3% of total oxygen consumption in state 3 (0.3-0.5 nmol ROS mg -1 protein min -1 ) at the habitat temperature, reaching a maximum of 4.3 % of state 3 respiration and 7 % of oligomycin-induced state 4+ respiration under heat stress. Thus, state 4 respiration, previously interpreted exclusively as a measure of proton leakage, included a significant contribution from ROS formation in this animal, especially under conditions of heat stress. Oxygen radical formation was directly dependent on temperature-controlled respiration rates in states 3 and 4 and inversely related to mitochondrial coupling (RCR+) in state 4. Mitochondrial ROS formation is therefore involved in cellular heat stress in this eurythermal marine ectotherm.

453 citations


Journal ArticleDOI
TL;DR: To characterize neutralizing epitopes, phages from a 12-mer phage display library were selected and two epitopes located in the ectodomain of PRRSV GP5 were identified, one of which was recognized both by neutralizing MAb ISU25-C1 and swine neutralizing serum (NS) but not by swine nonneutralized serum (NNS), indicating that it is aneutralizing epitope.
Abstract: After infection of swine with porcine reproductive and respiratory syndrome virus (PRRSV), there is a rapid rise of PRRSV-specific nonneutralizing antibodies (NNA), while neutralizing antibodies (NA) are detectable not sooner than 3 weeks later. To characterize neutralizing epitopes, we selected phages from a 12-mer phage display library using anti-PRRSV neutralizing monoclonal antibody (MAb) ISU25-C1. In addition, phages carrying peptides recognized by swine antibodies with high seroneutralizing titer were isolated after subtracting from the library those clones binding to swine anti-PRRSV serum with no neutralizing activity. Two epitopes located in the ectodomain of PRRSV GP5 were identified. One of these epitopes, which we named epitope B, was recognized both by neutralizing MAb ISU25-C1 and swine neutralizing serum (NS) but not by swine nonneutralizing serum (NNS), indicating that it is a neutralizing epitope. Epitope B is sequential, conserved among isolates, and not immunodominant. Antibodies directed against it are detected in serum late after infection. In contrast, the other epitope, which we named epitope A, is hypervariable and immunodominant. Antibodies against it appear early after infection with PRRSV. This epitope is recognized by swine NNA but is not recognized by either neutralizing MAb ISU25-C1 or swine NA, indicating that it is not involved in PRRSV neutralization. During infection with PRRSV, epitope A may act as a decoy, eliciting most of the antibodies directed to GP5 and delaying the induction of NA against epitope B for at least 3 weeks. These results are relevant to the design of vaccines against PRRSV.

420 citations


Journal ArticleDOI
TL;DR: The rainout-shelter design described here is a fixed-location shelter with a roof consisting of bands of transparent acrylic that blocks different amounts of rainfall while minimally affecting other environmental variables, and allows for proper replication in space, which is required in ecological field experiments.
Abstract: Field manipulative experiments represent a straightforward way to explore temporal relationships between annual precipitation and productivity. Water exclusion usually involves the use of rainout shelters, which are in general formed by a complete roof that intercepts 100% of the rainfall and require complicated mechanisms to move the shelter into place. The rainout-shelter design described here is a fixed-location shelter with a roof consisting of bands of transparent acrylic that blocks different amounts of rainfall while minimally affecting other environmental variables. We constructed thirty 3.76-m2 shelters in an arid steppe near Rio Mayo, Argentina (at 45°41′S, 70°16′W), to impose 30%, 55%, and 80% of rainfall interception. We tested the effectiveness of the design by collecting all the intercepted water in storage tanks and we evaluated changes in soil water content with the time domain reflectometry technique. We also measured soil water content in regular grids to assess the magnitude of the edge effect. We analysed the microclimate impact of the shelters by measuring photosynthetically active radiation and air and soil temperature inside and outside shelters. We did not detect significant differences between the observed and the expected rainfall interception for the 30% and 55% interception treatments but the 80% shelters intercepted 71% of incoming rainfall, which was significantly (P<0.05) lower than the expected value. Soil water content was significantly (P<0.05) higher in the control plots than in the plots with rainout shelter at all dates, except in January (summer). Radiation was not affected by the 30% interception treatment, but the roof with the largest number of acrylics bands (80% interception treatment) reduced incident radiation throughout the day by 10%. Air and soil temperatures were lower under than outside the shelters during the period of highest radiation but the opposite occurred with low radiation but with smaller differences. The two characteristics of the shelter, fixed design and low cost, allow for proper replication in space, which is required in ecological field experiments.

351 citations


Journal ArticleDOI
TL;DR: The results indicate that endogenous BDNF is required for both STM and LTM formation of an inhibitory avoidance learning, and suggest that this requirement involves ERK1/2‐dependent and ‐independent mechanisms.
Abstract: Information storage in the brain is a temporally graded process involving different memory types or phases. It has been assumed for over a century that one or more short-term memory (STM) processes are involved in processing new information while long-term memory (LTM) is being formed. Because brain-derived neutrophic factor (BDNF) modulates both short-term synaptic function and activity-dependent synaptic plasticity in the adult hippocampus, we examined the role of BDNF in STM and LTM formation of a hippocampal-dependent one-trial fear-motivated learning task in rats. Using a competitive RT-PCR quantitation method, we found that inhibitory avoidance training is associated with a rapid and transient increase in BDNF mRNA expression in the hippocampus. Bilateral infusions of function-blocking anti-BDNF antibody into the CA, region of the dorsal hippocampus decreased extracellular signal-regulated kinase 2 (ERK2) activation and impaired STM retention scores. Inhibition of ERK1/2 activation by PD098059 produced similar effects. In contrast, intrahippocampal administration of recombinant human BDNF increased ERK1/2 activation and facilitated STM. The infusion of anti-BDNF antibody impaired LTM when given 15 min before or 1 and 4 hr after training, but not at 0 or 6 hr posttraining, indicating that two hippocampal BDNF-sensitive time windows are critical for LTM formation. At the same time points, PD098059 produced no LTM deficits. Thus, our results indicate that endogenous BDNF is required for both STM and LTM formation of an inhibitory avoidance learning. Additionally, they suggest that this requirement involves ERK1/2-dependent and -independent mechanisms.

Journal ArticleDOI
TL;DR: A novel mechanism by which PKC regulates SK and increases secretion of S1P, allowing for autocrine/paracrine signaling is demonstrated, accompanied by a 4-fold increase in S1p in the media.

Journal ArticleDOI
TL;DR: It is shown that LTM formation of a one-trial inhibitory avoidance training in rats, a hippocampal-dependent form of contextual fear conditioning, depends on two consolidation periods requiring synthesis of new mRNAs, and suggests that the two time periods of anisomycin-induced amnesia depend at least in part on new mRNA synthesis.
Abstract: Information storage in the brain is a temporally graded process involving different memory types or phases. It has been assumed for over a century that one or more short-term memory (STM) processes are involved in processing new information while long-term memory (LTM) is being formed. It has been repeatedly reported that LTM requires de novo RNA synthesis around the time of training. Here we show that LTM formation of a one-trial inhibitory avoidance training in rats, a hippocampal-dependent form of contextual fear conditioning, depends on two consolidation periods requiring synthesis of new mRNAs. By injecting the RNA polymerase II inhibitors 5,6-dichloro-1-beta-d-ribofuranosylbenzimidazole or alpha-amanitin into the CA1 region of the dorsal hippocampus at various times before and after training, we found that hippocampal gene expression is critical in two time windows: around the time of training and 3-6 hr after training. Interestingly, these two periods of sensitivity to transcriptional inhibitors are similar to those observed using the protein synthesis inhibitor anisomycin. These findings underscore the parallel dependence of LTM formation of contextual fear on mRNA and protein synthesis in the hippocampus and suggest that the two time periods of anisomycin-induced amnesia depend at least in part on new mRNA synthesis.

Journal ArticleDOI
TL;DR: This review concerns the importance of zinc in growth, development, and cognitive function in children and the deleterious consequences of its deficiency on children's health.

Journal ArticleDOI
TL;DR: It can be concluded that the ingestion of antioxidant rich foods may prevent or delay primary and secondary effects associated with iron overload-related diseases.

Journal ArticleDOI
TL;DR: The main components of the hydrologic cycle of the La Plata basin in southeastern South America were investigated using a combination of observations, satellite products, and National Centers for Environmental Prediction (NCEP)-National Center for Atmospheric Research (NCAR) global reanalyses.
Abstract: The main components of the hydrologic cycle of the La Plata basin in southeastern South America are investigated using a combination of observations, satellite products, and National Centers for Environmental Prediction (NCEP)–National Center for Atmospheric Research (NCAR) global reanalyses. La Plata basin is second only to the Amazon basin in South America in river discharge and size and plays a critical role in the economies of the region. It is a primary factor in energy production, water resources, transportation, agriculture, and livestock. Of particular interest was the evaluation of the annual cycle of the hydrologic cycle components. The La Plata annual-mean river discharge is about 21 000 m3 s−1, and the amplitude of its mean annual cycle is small: it is slightly larger during late summer, but continues with large volumes even during winter. The reason for this is that different precipitation regimes over different locations contribute to the total river discharge. One regime is found t...

Journal ArticleDOI
TL;DR: It is suggested that UV-B radiation undoubtedly induces antioxidant defense system in sunflower cotyledons, allowing plant survival in spite of the oxidative stress generation, however, more research is necessary to elucidate the precise role that the antioxidant system plays underUV-B stress.

Journal ArticleDOI
01 Feb 2002-Ecology
TL;DR: In this article, the spatial relationship between aboveground net primary production (ANPP) and climate in the Patagonian steppe of South America was explored through time, considering the natural variations of ANPP and climate for 11 yr.
Abstract: We took advantage of regional gradients to study the spatial relationships between aboveground net primary production (ANPP) and climate in the Patagonian steppe of South America. We explored the same relationships through time, considering the natural variations of ANPP and climate for 11 yr. Based on NOAA/AVHRR satellite normalized difference vegetation index (NDVI) data, we evaluated the effects of climate on annual and seasonal ANPP across regional gradients of precipitation (100-500 mm/yr) and tem- perature (218-98C of annual mean). We studied ANPP climatic controls through time at four sites using NDVI and meteorological data. We used annual NDVI integral as a surrogate of annual ANPP. Annual NDVI integral increased linearly along regional gradients of precipitation, and its annual variability de- creased exponentially. Annual NDVI integral was, in most cases, unrelated to precipitation through time. We described the seasonality of ANPP using four variables derived from seasonal NDVI curves: the dates of growing season start and end, the date of maximum NDVI, and the length of the growing season. The growing season started later toward the cold extreme of the regional temperature gradients and, within a given site through time, during the coldest years. The dates of maximum NDVI and end of the growing season occurred later toward the humid or cold extremes of the regional gradients, whereas the length of the growing season was positively affected by precipitation and temperature along these gradients. These variables were not associated with climate through time. The response of the start of the growing season to temperature was greater in time, following the natural climatic fluctuations, than in space, accompanying regional temperature gradients. This difference probably resulted because the time required for shifts in community composition and plant adaptation is longer than one year. Climatic determinants of ANPP shifted from precipitation alone to precipitation plus temperature when the temporal scale of analysis changed from annual to seasonal. Our results indicate the feasibility of forecasting forage availability a few months prior to the beginning of the growing season, but not during the whole year. Longer term data sets and manipulative experiments are required to forecast annual ANPP and predict its response to climate change.

Journal ArticleDOI
TL;DR: The cumulative toxic effects of oxyradicals are considered the molecular mechanism of the behavioral deficits observed on aging.
Abstract: Behavioral tests, tightrope success, and exploratory activity in a T maze were conducted with male and female mice for 65 wk. Four groups were defined: the lower performance slow males and slow females and the higher performance fast males and fast females. Fast females showed the longest life span and the highest performance, and slow males showed the lowest performance and the shortest life span. Oxidative stress and mitochondrial electron transfer activities were determined in brain of young (28 wk), adult (52 wk), and old (72 wk) mice in a cross-sectional study. Brain thiobarbituric acid reactive substances (TBARS) were increased by 50% in old mice and were ∼15% higher in males than in females and in slow than in fast mice. Brain Cu,Zn-superoxide dismutase (SOD) activity was increased by 52% and Mn-SOD by 108% in old mice. The activities of mitochondrial enzymes NADH-cytochrome c reductase, cytochrome oxidase, and citrate synthase were decreased by 14–58% in old animals. The cumulative toxic effects of oxyradicals are considered the molecular mechanism of the behavioral deficits observed on aging.

Journal ArticleDOI
TL;DR: The state-of-the-art of the effects of galectins in inflammatory and immunomodulatory processes and their glycoligands in the progression, diagnosis and treatment of different pathological processes such as autoimmunity, allergy, infection and chronic inflammation are summarized.

Journal ArticleDOI
TL;DR: In this article, the effect of crushed sand on high-strength concrete has been analyzed using three different types of crushed sands (granite, limestone and dolomite) with similar grading.

Journal ArticleDOI
TL;DR: In this paper, the authors analyzed a data set of 610 district-level nomination processes for the biennial Argentine Chamber of Deputies elections held between 1983 and 2001 and concluded that several specific institutional and partisan features have a prominent effect on the probability that a political party will choose its candidates at the ballot box (direct primary) rather than in a smoke-filled back room (elite arrangement).
Abstract: How political parties select their candidates for public office profoundly affects the types of people who are elected as well as how these people behave in office. This selection process also provides important insights on how parties function internally and on where political power is located within a country. Only a few comparative studies of nomination procedures exist, and none explain why some parties at some points in time select candidates via direct primaries and others do not. The authors analyze an original data set of 610 district-level nomination processes for the biennial Argentine Chamber of Deputies elections held between 1983 and 2001. They conclude that several specific institutional and partisan features have a prominent effect on the probability that a political party will choose its candidates at the ballot box (direct primary) rather than in a smoke-filled back room (elite arrangement).

Journal ArticleDOI
TL;DR: In this paper, the authors present a conceptual comprehensive numerical procedure for the performance-based seismic design of buildings and discuss the main requirements that a reliable PBSD should satisfy and why some approaches that have been proposed fail in satisfying those requirements, focusing on what is considered a promising probabilistic PBSD approach.
Abstract: The main objectives of this paper are: (i) to review briefly as to what is understood by performance-based engineering, performance-based seismic engineering, and performance-based seismic design (PBSD); (ii) to discuss the main requirements that a reliable PBSD should satisfy and why some approaches that have been proposed fail in satisfying those requirements; (iii) to focus on what is considered a promising probabilistic PBSD approach; and (iv) to present a conceptual comprehensive numerical procedure for the PBSD of buildings. It is shown that to satisfy the objectives of a reliable PBSD philosophy and procedure it is necessary to start with a multi-level seismic design criteria, to consider a probabilistic design approach, to consider local structural and non-structural damage and therefore design spectra for buildings (n degrees of freedom), to take into account the cumulative damage, and to control not only displacements but also ductility (minimum strength) to limit damage. Finally, it is concluded that a transparent and conceptual comprehensive preliminary design approach is necessary. Copyright © 2001 John Wiley & Sons, Ltd.

Journal ArticleDOI
TL;DR: In this paper, an isolated active region (AR) was observed on the Sun during seven rotations, starting from its birth in July 1996 to its full dispersion in December 1996.
Abstract: An isolated active region (AR) was observed on the Sun during seven rotations, starting from its birth in July 1996 to its full dispersion in December 1996. We analyse the long-term budget of the AR relative magnetic helicity. Firstly, we calculate the helicity injected by differential rotation at the photospheric level using MDI/SoHO magnetograms. Secondly, we compute the coronal magnetic field and its helicity selecting the model which best fits the soft X-ray loops observed with SXT/Yohkoh. Finally, we identify all the coronal mass ejections (CMEs) that originated from the AR during its lifetime using LASCO and EIT/SoHO. Assuming a one to one correspondence between CMEs and magnetic clouds, we estimate the magnetic helicity which could be shed via CMEs. We find that differential rotation can neither provide the required magnetic helicity to the coronal field (at least a factor 2.5 to 4 larger), nor to the field ejected to the interplanetary space (a factor 4 to 20 larger), even in the case of this AR for which the total helicity injected by differential rotation is close to the maximum possible value. However, the total helicity ejected is equivalent to that of a twisted flux tube having the same magnetic flux as the studied AR and a number of turns in the interval [0.5, 2.0]. We suggest that the main source of helicity is the inherent twist of the magnetic flux tube forming the active region. This magnetic helicity is transferred to the corona either by the continuous emergence of the flux tube for several solar rotations (i.e. on a time scale much longer than the classical emergence phase), or by torsional Alfven waves.

Journal ArticleDOI
TL;DR: To design linguistic models which are accurate to a high degree and may be suitably interpreted, the structure of the knowledge base of fuzzy rule base systems is extended in a hierarchical way, in order to make it more flexible.
Abstract: In this paper, we propose an approach to design linguistic models which are accurate to a high degree and may be suitably interpreted. This approach is based on the development of a hierarchical system of linguistic rules learning methodology. This methodology has been thought as a refinement of simple linguistic models which, preserving their descriptive power, introduces small changes to increase their accuracy. To do so, we extend the structure of the knowledge base of fuzzy rule base systems in a hierarchical way, in order to make it more flexible. This flexibilization will allow us to have linguistic rules defined over linguistic partitions with different granularity levels, and thus to improve the modeling of those problem subspaces where the former models have bad performance.

Journal ArticleDOI
TL;DR: The metabolism ofcumulus cells is adapted to control the flow of metabolites toward the oocyte, which maintains its enzymatic activity even when dissociated from cumulus cells during maturation, indicating that glucose is metabolized mainly via the glycolytic pathway in these cells.
Abstract: Little is known about the metabolic profile of cumulus-oocyte complexes (COCs) during maturation. The aim of this study was to determine the differential participation of enzymatic activity in cumulus cells and the oocyte during in vitro maturation of bovine oocytes, by measuring the activity of key enzymes involved in the regulation of glycolysis (phosphofructokinase), the pentose phosphate pathway (glucose-6-phosphate dehydrogenase) and lipolysis (lipase). COCs were matured in medium 199 plus 10% (v/v) steer serum for 22-24 h at 39 degrees C in 5% CO(2):95% humidified air. Phosphofructokinase, glucose-6-phosphate dehydrogenase and lipase activities were measured in immature and in vitro matured COCs, denuded oocytes and cumulus cells, respectively. Phosphofructokinase and glucose-6-phosphate dehydrogenase activities (enzymatic units) remained constant during in vitro maturation of COCs, but there was a significant decrease in lipase activity (units) (P < 0.05), as activity in cumulus cells decreased significantly (P < 0.05). For the three enzymes studied, enzyme activity (units) remained unchanged in the oocyte during in vitro maturation. Specific activity increased in the oocyte (P < 0.05) and decreased in cumulus cells as a result of maturation (P < 0.05). In cumulus cells, phosphofructokinase was the most abundant of the three enzymes followed by glucose-6-phosphate dehydrogenase and then lipase (P < 0.05), whereas in the denuded oocyte this order was reversed (P < 0.05). Thus, the metabolism of cumulus cells is adapted to control the flow of metabolites toward the oocyte, which maintains its enzymatic activity even when dissociated from cumulus cells during maturation. The high activity of phosphofructokinase in cumulus cells indicates that glucose is metabolized mainly via the glycolytic pathway in these cells. The greater relative activity of glucose-6-phosphate dehydrogenase recorded in the oocyte indicates that glucose uptake could be directed mainly toward the pentose phosphate pathway. The marked lipolytic activity concentrated in the oocyte indicates an active participation in lipid catabolism during maturation.

Journal ArticleDOI
TL;DR: Methanolic extracts from Achyrocline satureioides, unlike those from Celtis spinosa Spreng, Chenopodium ambrosioides L., Petiveria alliacea L., and Plantago major L. showed cytotoxic activity against a human hepatocellular carcinoma cell line, Hep G2.

Journal Article
TL;DR: Melatonin treatment seems to constitute a selection therapy to ameliorate sundowning and to slow evolution of cognitive impairment in AD patients, an effect seen regardless of the concomitant medication employed to treat cognitive or behavioral signs of AD.
Abstract: About 45% of Alzheimer's disease (AD) patients have disruptions in their sleep and sundowning agitation. Since melatonin secretion is greatly inhibited in AD patients we have used melatonin to treat sleep disorders in AD patients since 1995. In a first study [21] we reported, in 7 out of 10 dementia patients treated with melatonin (3 mg p.o. at bed time), a decreased sundowning. In a second study [22] we examined 14 AD patients who received 9 mg melatonin daily for 22 to 35 months, observing a significant improvement of sleep quality with stabilization of behavioral and cognitive parameters. In a third study [23] we reported two monozygotic twins with AD and similar cognitive impairment, one of them receiving 6 mg melatonin at bedtime daily for 3 years. Melatonin treatment improved sleep quality and suppressed sundowning. We now report the effect of melatonin (4-month-long treatment with 6 mg/day) in 45 AD patients with sleep disturbances. Melatonin improved sleep and suppressed sundowning, an effect seen regardless of the concomitant medication employed to treat cognitive or behavioral signs of AD. Melatonin treatment seems to constitute a selection therapy to ameliorate sundowning and to slow evolution of cognitive impairment in AD patients.

Journal ArticleDOI
TL;DR: In this paper, the authors considered type IIB string in two plane-wave backgrounds which may be interpreted as special limits of the AdS_3 x S^3 metric supported by either the NS-NS or R-R 3-form field.
Abstract: We consider type IIB string in the two plane-wave backgrounds which may be interpreted as special limits of the AdS_3 x S^3 metric supported by either the NS-NS or R-R 3-form field. The NS-NS plane-wave string model is equivalent to a direct generalization of the Nappi-Witten model, with its spectrum being similar to that of strings in constant magnetic field. The R-R model can be solved in the light-cone gauge, where the Green-Schwarz action describes 4 massive and 4 massless copies of free bosons and fermions. We find the spectra of the two string models and study the asymptotic density of states. We also discuss a more general class of exactly solvable plane-wave models with reduced supersymmetry which is obtained by adding twists in two spatial 2-planes.

Journal ArticleDOI
TL;DR: It is suggested that peak cough flow–peak expiratory flow is useful to monitor expiratories muscle weakness and bulbar involvement and to assess its evolution in patients with neuromuscular diseases.
Abstract: Suarez AA, Pessolano FA, Monteiro SG, Ferreyra G, Capria ME, Mesa L, Dubrovsky A, De Vito EL: Peak flow and peak cough flow in the evaluation of expiratory muscle weakness and bulbar impairment in patients with neuro- muscular diseases. Am J Phys Med Rehabil 2002;81:506-511. Objective: To study the expiratory muscle force and the ability to cough estimated by the peak expiratory flow and peak cough flow in patients with Duchenne muscular dystrophy and amyotrophic lateral sclerosis. Design: A total of 27 patients with amyotrophic lateral sclerosis and 52 patients with Duchenne muscular dystrophy were studied. From the group of 144 normal subjects of this laboratory, we selected 38 for comparison. Results: The maximal inspiratory pressure in patients with Duchenne mus- cular dystrophy and amyotrophic lateral sclerosis was 64.5 24.7% and 37.8 21.8%, respectively, and maximal expiratory pressure was 64.2 32.5% and 37.7 21.6%, respectively. Patient groups showed a significant lower peak expiratory flow than normal subjects. Higher peak cough flow than peak expiratory flow was found in all groups. The peak cough flow-peak expiratory flow difference was 46 18% in normal subjects, 43 23% in patients with Duchenne muscular dystrophy, and 11 17% in patients with amyotrophic lateral sclerosis. The peak expiratory flow and peak cough flow were not different in bulbar onset amyotrophic lateral sclerosis. In patient groups, the dynamic and static behavior correlated positively.