Showing papers by "University of Buenos Aires published in 2006"
TL;DR: In this paper, the authors describe expression of CB2-receptor-like immunoreactivity in brain in neuronal patterns that support broader CNS roles for this receptor, and also support the expression of brain CB2 receptor transcripts at levels much lower than those of CB1 receptors.
767 citations
University of Buenos Aires1, National Oceanic and Atmospheric Administration2, University of Costa Rica3, University of São Paulo4, University of Chile5, National Center for Atmospheric Research6, University of New Mexico7, University of Washington8, National Institute for Space Research9, University of California, Los Angeles10, University of Utah11, University of Miami12
TL;DR: This paper reviewed recent progress in the understanding of the American monsoon systems and identified some of the future challenges that remain to improve warm season climate prediction, including new insights into moisture transport processes, description of the structure and variability of the South American low level jet, and resolution of the diurnal cycle of precipitation in the core monsoon regions.
Abstract: An important goal of the Climate Variability and Predictability (CLIVAR) research on the American monsoon systems is to determine the sources and limits of predictability of warm season precipitation, with emphasis on weekly to interannual time scales. This paper reviews recent progress in the understanding of the American monsoon systems and identifies some of the future challenges that remain to improve warm season climate prediction. Much of the recent progress is derived from complementary international programs in North and South America, namely, the North American Monsoon Experiment (NAME) and the Monsoon Experiment South America (MESA), with the following common objectives: 1) to understand the key components of the American monsoon systems and their variability, 2) to determine the role of these systems in the global water cycle, 3) to improve observational datasets, and 4) to improve simulation and monthly-to-seasonal prediction of the monsoons and regional water resources. Among the recent observational advances highlighted in this paper are new insights into moisture transport processes, description of the structure and variability of the South American low-level jet, and resolution of the diurnal cycle of precipitation in the core monsoon regions. NAME and MESA are also driving major efforts in model development and hydrologic applications. Incorporated into the postfield phases of these projects are assessments of atmosphere–land surface interactions and model-based climate predictability experiments. As CLIVAR research on American monsoon systems evolves, a unified view of the climatic processes modulating continental warm season precipitation is beginning to emerge.
719 citations
TL;DR: It is concluded that photodegradation is a dominant control on above-ground litter decomposition in this semi-arid ecosystem and future changes in radiation interception due to decreased cloudiness, increased stratospheric ozone depletion, or reduced vegetative cover may have a more significant effect on the carbon balance in these water-limited ecosystems than changes in temperature or precipitation.
Abstract: Biological processes are thought to be the primary cause of decomposition of organic matter in terrestrial ecosystems, with abiotic processes such as degradation by UV-B radiation playing a minor role. Not so, according to a study in the semi-arid Patagonian steppe. Here solar radiation has been identified as a major influence on carbon turnover. Blocking full sunlight or UV-B radiation dramatically reduced the rate of decomposition of plant litter, yet, reduction of soil organisms or addition of limiting soil resources had no effect. These results suggest a short-circuit in the carbon cycle; a substantial fraction of primary production could be lost to the atmosphere via photodegradation without cycling through soil organic matter pools. As nearly 40% of Earth's land surface is desert, global change affecting levels of radiation such as ozone depletion or cloud cover could have major impacts on carbon storage. Solar radiation is a dominant control on the rate of leaf litter decomposition in the semi-arid Patagonian steppe, which suggests that factors such as cloud cover may influence carbon cycling in semi-arid environments. The carbon balance in terrestrial ecosystems is determined by the difference between inputs from primary production and the return of carbon to the atmosphere through decomposition of organic matter1. Our understanding of the factors that control carbon turnover in water-limited ecosystems is limited, however, as studies of litter decomposition have shown contradictory results and only a modest correlation with precipitation2,3,4,5. Here we evaluate the influence of solar radiation, soil biotic activity and soil resource availability on litter decomposition in the semi-arid Patagonian steppe using the results of manipulative experiments carried out under ambient conditions of rainfall and temperature. We show that intercepted solar radiation was the only factor that had a significant effect on the decomposition of organic matter, with attenuation of ultraviolet-B and total radiation causing a 33 and 60 per cent reduction in decomposition, respectively. We conclude that photodegradation is a dominant control on above-ground litter decomposition in this semi-arid ecosystem. Losses through photochemical mineralization may represent a short-circuit in the carbon cycle, with a substantial fraction of carbon fixed in plant biomass being lost directly to the atmosphere without cycling through soil organic matter pools. Furthermore, future changes in radiation interception due to decreased cloudiness, increased stratospheric ozone depletion, or reduced vegetative cover may have a more significant effect on the carbon balance in these water-limited ecosystems than changes in temperature or precipitation.
681 citations
University of East Anglia1, National Institute for Space Research2, University of São Paulo3, University of Buenos Aires4, Universidade Federal do Rio Grande do Sul5, University of the Republic6, Universidad Nacional de Asunción7, National Agrarian University8, Federal University of Paraná9, University of Oklahoma10, Federal University of Pará11, Escuela Superior Politecnica del Litoral12, Meteorological Service of Canada13
TL;DR: A weeklong workshop in Brazil in August 2004 provided the opportunity for 28 scientists from southern South America to examine daily rainfall observations to determine changes in both total and extreme rainfall as mentioned in this paper.
Abstract: A weeklong workshop in Brazil in August 2004 provided the opportunity for 28 scientists from southern South America to examine daily rainfall observations to determine changes in both total and extreme rainfall. Twelve annual indices of daily rainfall were calculated over the period 1960 to 2000, examining changes to both the entire distribution as well as the extremes. Maps of trends in the 12 rainfall indices showed large regions of coherent change, with many stations showing statistically significant changes in some of the indices. The pattern of trends for the extremes was generally the same as that for total annual rainfall, with a change to wetter conditions in Ecuador and northern Peru and the region of southern Brazil, Paraguay, Uruguay, and northern and central Argentina. A decrease was observed in southern Peru and southern Chile, with the latter showing significant decreases in many indices. A canonical correlation analysis between each of the indices and sea surface temperatures (SSTs) revealed two large-scale patterns that have contributed to the observed trends in the rainfall indices. A coupled pattern with ENSO-like SST loadings and rainfall loadings showing similarities with the pattern of the observed trend reveals that the change to a generally more negative Southern Oscillation index (SOI) has had an important effect on regional rainfall trends. A significant decrease in many of the rainfall indices at several stations in southern Chile and Argentina can be explained by a canonical pattern reflecting a weakening of the continental trough leading to a southward shift in storm tracks. This latter signal is a change that has been seen at similar latitudes in other parts of the Southern Hemisphere. A similar analysis was carried out for eastern Brazil using gridded indices calculated from 354 stations from the Global Historical Climatology Network (GHCN) database. The observed trend toward wetter conditions in the southwest and drier conditions in the northeast could again be explained by changes in ENSO.
646 citations
TL;DR: Using output from global chemistry transport models, this article provided the first estimates of recent (mid-1990s) and future (2050) rates and distributions of atmospheric nitrogen (N) deposition within biodiversity hotspots.
Abstract: Increased atmospheric nitrogen (N) deposition is known to reduce plant diversity in natural and semi-natural ecosystems, yet our understanding of these impacts comes almost entirely from studies in northern Europe and North America. Currently, we lack an understanding of the threat of N deposition to biodiversity at the global scale. In particular, rates of N deposition within the newly defined 34 world biodiversity hotspots, to which 50% of the world’s floristic diversity is restricted, has not been quantified previously. Using output from global chemistry transport models, here we provide the first estimates of recent (mid-1990s) and future (2050) rates and distributions of N deposition within biodiversity hotspots. Our analysis shows that the average deposition rate across these areas was 50% greater than the global terrestrial average in the mid1990s and could more than double by 2050, with 33 of 34 hotspots receiving greater N deposition in 2050 compared with 1990. By this time, 17 hotspots could have between 10% and 100% of their area receiving greater than 15kgNha � 1 yr � 1 , a rate exceeding critical loads set for many sensitive European ecosystems. Average deposition in four hotspots is predicted to be greater than 20kgNha � 1 yr � 1 . This elevated N deposition within areas of high plant diversity and endemism may exacerbate significantly the global threat of N deposition to world floristic diversity. Overall, we highlight the need for a greater global approach to assessing the impacts of N deposition.
532 citations
TL;DR: It is demonstrated that CB2 CBrs and their gene transcripts are widely distributed in the brain, contrary to the prevailing view that CB 2 CBrs are restricted to peripheral tissues and predominantly in immune cells.
Abstract: Two well-characterized cannabinoid receptors (CBrs), CB1 and CB2, mediate the effects of cannabinoids and marijuana use, with functional evidence for other CBrs. CB1 receptors are expressed primarily in brain and peripheral tissues. For over a decade several laboratories were unable to detect CB2 receptors in brain and were known to be intensely expressed in peripheral and immune tissues and have traditionally been referred to as peripheral CB2 CBrs. We have reported the discovery and functional presence of CB2 cannabinoid receptors in mammalian brain that may be involved in depression and drug abuse and this was supported by reports of identification of neuronal CB2 receptors that are involved in emesis. We used RT-PCR, immunoblotting, hippocampal cultures, immunohistochemistry, transmission electron microscopy, and stereotaxic techniques with behavioral assays to determine the functional expression of CB2 CBrs in rat brain and mice brain exposed to chronic mild stress (CMS) or those treated with abused drugs. RT-PCR analyses supported the expression of brain CB2 receptor transcripts at levels much lower than those of CB1 receptors. In situ hybridization revealed CB2 mRNA in cerebellar neurons of wild-type but not of CB2 knockout mice. Abundant CB2 receptor immunoreactivity (iCB2) in neuronal and glial processes was detected in brain and CB2 expression was detected in neuron-specific enolase (NSE) positive hippocampal cell cultures. The effect of direct CB2 antisense oligonucleotide injection into the brain and treatment with JWH015 in motor function and plus-maze tests also demonstrated the functional presence of CB2 cannabinoid receptors in the central nervous system (CNS). Thus, contrary to the prevailing view that CB2 CBrs are restricted to peripheral tissues and predominantly in immune cells, we demonstrated that CB2 CBrs and their gene transcripts are widely distributed in the brain. This multifocal expression of CB2 immunoreactivity in brain suggests that CB2 receptors may play broader roles in the brain than previously anticipated and may be exploited as new targets in the treatment of depression and substance abuse.
520 citations
TL;DR: There is so much proof about endothelium dysfunction that it is reasonable to believe that there is diagnostic and prognostic value in its evaluation for the late outcome, and there is no doubt that endothelial dysfunction contributes to the initiation and progression of atherosclerotic disease and could be considered an independent vascular risk factor.
Abstract: The endothelium is a thin monocelular layer that covers all the inner surface of the blood vessels, separating the circulating blood from the tissues. It is not an inactive organ, quite the opposite. It works as a receptor-efector organ and responds to each physical or chemical stimulus with the release of the correct substance with which it may maintain vasomotor balance and vascular-tissue homeostasis. It has the property of producing, independently, both agonistic and antagonistic substances that help to keep homeostasis and its function is not only autocrine, but also paracrine and endocrine. In this way it modulates the vascular smooth muscle cells producing relaxation or contraction, and therefore vasodilatation or vasoconstriction. The endothelium regulating homeostasis by controlling the production of prothrombotic and antithrombotic components, and fibrynolitics and antifibrynolitics. Also intervenes in cell proliferation and migration, in leukocyte adhesion and activation and in immunological and inflammatory processes. Cardiovascular risk factors cause oxidative stress that alters the endothelial cells capacity and leads to the so called endothelial "dysfunction" reducing its capacity to maintain homeostasis and leads to the development of pathological inflammatory processes and vascular disease. There are different techniques to evaluate the endothelium functional capacity, that depend on the amount of NO produced and the vasodilatation effect. The percentage of vasodilatation with respect to the basal value represents the endothelial functional capacity. Taking into account that shear stress is one of the most important stimulants for the synthesis and release of NO, the non-invasive technique most often used is the transient flow-modulate "endothelium-dependent" post-ischemic vasodilatation, performed on conductance arteries such as the brachial, radial or femoral arteries. This vasodilatation is compared with the vasodilatation produced by drugs that are NO donors, such as nitroglycerine, called "endothelium independent". The vasodilatation is quantified by measuring the arterial diameter with high resolution ultrasonography. Laser-Doppler techniques are now starting to be used that also consider tissue perfusion. There is so much proof about endothelial dysfunction that it is reasonable to believe that there is diagnostic and prognostic value in its evaluation for the late outcome. There is no doubt that endothelial dysfunction contributes to the initiation and progression of atherosclerotic disease and could be considered an independent vascular risk factor. Although prolonged randomized clinical trials are needed for unequivocal evidence, the data already obtained allows the methods of evaluation of endothelial dysfunction to be considered useful in clinical practice and have overcome the experimental step, being non-invasive increases its value making it use full for follow-up of the progression of the disease and the effects of different treatments.
470 citations
TL;DR: In this paper, deep optical observations of GRB 060614 showed no emerging supernova with absolute visual magnitude brighter than M(V) = -13.7, indicating that any supernova associated with GRB060614 was at least 100 times fainter, at optical wavelengths, than the other supernovae associated withGRBs.
Abstract: Gamma-ray bursts (GRBs) are short, intense flashes of soft gamma-rays coming from the distant Universe. Long-duration GRBs (those lasting more than approximately 2 s) are believed to originate from the deaths of massive stars, mainly on the basis of a handful of solid associations between GRBs and supernovae. GRB 060614, one of the closest GRBs discovered, consisted of a 5-s hard spike followed by softer, brighter emission that lasted for approximately 100 s (refs 8, 9). Here we report deep optical observations of GRB 060614 showing no emerging supernova with absolute visual magnitude brighter than M(V) = -13.7. Any supernova associated with GRB 060614 was therefore at least 100 times fainter, at optical wavelengths, than the other supernovae associated with GRBs. This demonstrates that some long-lasting GRBs can either be associated with a very faint supernova or produced by different phenomena.
446 citations
15 Sep 2006-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: The D0 experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996 as discussed by the authors, and the detector has been upgraded to take advantage of improvements to the Tevoton and to enhance its physics capabilities.
Abstract: The D0 experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996. Since then, the detector has been upgraded to take advantage of improvements to the Tevatron and to enhance its physics capabilities. We describe the new elements of the detector, including the silicon microstrip tracker, central fiber tracker, solenoidal magnet, preshower detectors, forward muon detector, and forward proton detector. The uranium/liquid-argon calorimeters and central muon detector, remaining from Run I, are discussed briefly. We also present the associated electronics, triggering, and data acquisition systems, along with the design and implementation of software specific to D0.
425 citations
TL;DR: Memory consolidation involves a complex network of brain systems and serial and parallel molecular events, even for a task as deceptively simple as one-trial avoidance, and is proposed that these molecular events might also be involved in many other memory types in animals and humans.
417 citations
TL;DR: In this article, the transverse-momentum distribution of generic high-mass systems (lepton pairs, vector bosons, Higgs particles, etc) produced in hadron collisions is considered, and all-order resummation of the logarithmically-enhanced contributions in QCD perturbation theory is investigated.
TL;DR: The substantial differences observed in age‐specific curves of HPV prevalence between populations may have a variety of explanations, however, underline that great caution should be used in inferring the natural history of HPV from age-specific prevalences.
Abstract: An inverse relationship between age and human papillomavirus (HPV) prevalence has been reported in many developed countries, but information on this relationship is scarce in many other parts of the world We carried out a cross-sectional study of sexually active women from the general population of 15 areas in 4 continents Similar standardised protocols for women's enrolment, cervical specimen collection and PCR-based assays for HPV testing were used HPV prevalence in different age groups was compared by study area 18,498 women aged 15-74 years were included Age-standardised HPV prevalence varied more than 10-fold between populations, as did the shape of age-specific curves HPV prevalence peaked below age 25 or 35, and declined with age in Italy, the Netherlands, Spain, Argentina, Korea and in Lampang, Thailand and Ho Chi Minh, Vietnam This was not the case in Songkla, Thailand nor Hanoi, Vietnam, where HPV prevalence was low in all age groups In Chile, Colombia and Mexico, a second peak of HPV prevalence was detected among older women In the poorest study areas in Asia (Shanxi, China and Dindigul, India), and in Nigeria, HPV prevalence was high across all age groups The substantial differences observed in age-specific curves of HPV prevalence between populations may have a variety of explanations These differences, however, underline that great caution should be used in inferring the natural history of HPV from age-specific prevalences
TL;DR: A new nonparametric VSS-NLMS is proposed that is easy to control and gives good performances in the context of acoustic echo cancellation.
Abstract: The aim of a variable step size normalized least-mean-square (VSS-NLMS) algorithm is to try to solve the conflicting requirement of fast convergence and low misadjustment of the NLMS algorithm. Numerous VSS-NLMS algorithms can be found in the literature with a common point for most of them: they may not work very reliably since they depend on several parameters that are not simple to tune in practice. The objective of this letter is twofold. First, we explain a simple and elegant way to derive VSS-NLMS-type algorithms. Second, a new nonparametric VSS-NLMS is proposed that is easy to control and gives good performances in the context of acoustic echo cancellation
TL;DR: It is demonstrated that flavanols either isolated or present in foods could inhibit ACE activity, supported by the association between the consumption of flavanol-rich foods and reductions in blood pressure observed in several experimental models.
Abstract: Angiotensin converting enzyme (ACE) activity was evaluated in the presence of flavanol-rich foods, i.e., wines, chocolates, and teas, and of purified flavonoids. All foods assayed inhibited ACE activity, red wines being more effective than white wine, and green tea more effective than black tea. The inhibition of ACE activity was associated with both phenolic and flavanol content in the foods. When isolated polyphenols were assayed, procyanidins (dimer and hexamer) and epigallocatechin significantly inhibited enzyme activity; similar concentrations of (+)-catechin, (-)-epicatechin, gallic acid, chlorogenic acid, caffeic acid, quercetin, kaempferol, and resveratrol were ineffective. When ACE activity was assayed in rat kidney membranes in the presence of chocolate extracts or purified procyanidins, it was observed that the inhibition depended on the chocolate content of flavanols and the number of flavanol units constituting the procyanidin. These experiments demonstrate that flavanols either isolated or present in foods could inhibit ACE activity. The occurrence of such inhibition in vivo needs to be determined, although is supported by the association between the consumption of flavanol-rich foods and reductions in blood pressure observed in several experimental models.
TL;DR: The South American Low-Level Jet (SALLJ) as mentioned in this paper is a low-level jet (LJ) with the strongest winds found over eastern Bolivia, and is present all year and channels moisture to the La Plata basin, which is analogous to the better-known Amazon basin in terms of its biological and habitat diversity.
Abstract: Moisture is transported in South America westward from the tropical Atlantic Ocean to the Amazon basin, and then southward toward the extratropics. A regional intensification of this circulation to the east of the Andes Mountains is called the South American low-level jet (SALLJ), with the strongest winds found over eastern Bolivia. SALLJ is present all year and channels moisture to the La Plata basin, which is analogous to the better-known Amazon basin in terms of its biological and habitat diversity, and far exceeds the latter in its economic importance to southern and central South America in terms of hydroelectricity and food production. The relatively small SALLJ spatial scale (compared with the density of the available sounding network) has a limited understanding of and modeling capability for any variations in the SALLJ intensity and structure as well as its possible relationship to downstream rainfall. The SALLJ Experiment (SALLJEX), aimed at describing many aspects of SALLJ, was carried...
TL;DR: This work identified an anti‐inflammatory cytokine, TGF‐β, with neurogenic potential in the adult brain, and supports the idea that activated microglial cells are not pro‐ or anti‐neurogenic per se, but the balance between pro‐ and anti-inflammatory secreted molecules influences the final effect of this activation.
Abstract: Adult neural stem cells (NSC) proliferate and differentiate depending on the composition of the cellular and molecular niche in which they are immersed. Until recently, microglial cells have been ignored as part of the neurogenic niche. We studied the dynamics of NSC proliferation and differentiation in the dentate gyrus of the hippocampus (DG) and characterized the changes of the neurogenic niche in adrenalectomized animals (ADX). At the cellular level, we found increased NSC proliferation and neurogenesis in the ADX animals. In addition, a morphologically distinct subpopulation of NSC (Nestin+/GFAP-) with increased proliferating profile was detected. Interestingly, the number of microglial cells at stages 2 and 3 of activation correlated with increased neurogenesis (r2 = 0.999) and the number of Nestin-positive cells (r2 = 0.96). At the molecular level, transforming growth factor beta (TGF-beta) mRNA levels were increased 10-fold in ADX animals. Interestingly, TGF-beta levels correlated with the amount of neurogenesis detected (r2 = 0.99) and the number of stage 2 and 3 microglial cells (r2 = 0.94). Furthermore, blockade of TGF-beta biological activity by administration of an anti-TGF-beta type II receptor antibody diminished the percentage of 5-bromo-2'-deoxyuridine (BrdU)/PSA-NCAM-positive cells in vivo. Moreover, TGF-beta was able to promote neurogenesis in NSC primary cultures. This work supports the idea that activated microglial cells are not pro- or anti-neurogenic per se, but the balance between pro- and anti-inflammatory secreted molecules influences the final effect of this activation. Importantly, we identified an anti-inflammatory cytokine, TGF-beta, with neurogenic potential in the adult brain.
TL;DR: In this paper, the authors studied the asymptotic behavior of nonlocal diffusion models with Dirichlet or Neumann boundary conditions and showed that the long time behavior of the solutions is determined by the Fourier transform of J near the origin, which is linked to the behavior of J at infinity.
TL;DR: In this paper, the determinants of innovative inputs and outputs and their impacts on manufacturing firms' productivity in developing countries were analyzed using panel data from innovation surveys in Argentina with information for 1992-2001 and showed that large firms have a higher probability of engaging in innovation activities and of becoming innovators.
TL;DR: Data reported here suggest that NO is an endogenous metabolite in soybean chloroplasts and that reactive nitrogen species could exert either antioxidant or prooxidant effects on chloroplast macromolecules.
Abstract: Nitric oxide (NO) generation by soybean (Glycine max var. ADM 4800) chloroplasts was studied as an endogenous product assessed by the electron paramagnetic resonance spin-trapping technique. Nitrite and l-arginine (Arg) are substrates for enzymatic activities considered to be the possible sources of NO in plants. Soybean chloroplasts showed a NO production of 3.2 +/- 0.2 nmol min(-1) mg(-1) protein in the presence of 1 mm NaNO(2). Inhibition of photosynthetic electron flow by 3-(3,4-dichlorophenyl)-1,1-dimethyl urea resulted in a lower rate (1.21 +/- 0.04 nmol min(-1) mg(-1) protein) of NO generation. Chloroplasts incubated with 1 mm Arg showed NO production of 0.76 +/- 0.04 nmol min(-1) mg(-1) protein that was not affected either by omission of Ca(2+) or by supplementation with Ca(2+) and calmodulin to the incubation medium. This production was inhibited when chloroplasts were incubated in the presence of NO synthase inhibitors N(omega)-nitro-l-Arg methyl ester hydrochloride and N(omega)-nitro-l-Arg. In vitro exposure of chloroplasts to an NO donor (250 mum S-nitrosoglutathione) decreased lipid radical content in membranes by 29%; however, incubation in the presence of 25 mum peroxynitrite (ONOO(-)) led to an increase in lipid-derived radicals (34%). The effect of ONOO(-) on protein oxidation was determined by western blotting, showing an increase in carbonyl content either in stroma or thylakoid proteins as compared to controls. Moreover, ONOO(-) treatment significantly affected both O(2) evolution and chlorophyll fluorescence in thylakoids. Data reported here suggest that NO is an endogenous metabolite in soybean chloroplasts and that reactive nitrogen species could exert either antioxidant or prooxidant effects on chloroplast macromolecules.
TL;DR: The role of melatonin in the pathophysiology of bipolar disorder and SAD is discussed and bright light treatment, that suppresses melatonin production, is effective in treating bipolar affective disorder andSAD, winter type.
Abstract: The cyclic nature of depressive illness, the diurnal variations in its symptomatology and the existence of disturbed sleep–wake and core body temperature rhythms, all suggest that dysfunction of th...
TL;DR: In this article, a subset of climate simulations of the 20th century from the IPCC-AR4 is analyzed to assess the ability of these models to reproduce the observed climatological seasonal precipitation in South America during the period 1970-1999.
Abstract: [1] A subset of climate simulations of the 20th century from the IPCC-AR4 is analyzed to assess the ability of these models to reproduce the observed climatological seasonal precipitation in South America during the period 1970–1999. Changes of the model climatology in a climate change scenario (SRESA1b) for the period 2070–2099 are also discussed. Results show that models are able to reproduce the main features of the precipitation seasonal cycle over South America, although the precipitation in the SACZ region and the precipitation maximum over southeastern South America observed during the cold season are not well- represented. There is a general consensus among models that the precipitation changes projected are mainly: i) an increase of summer precipitation over southeastern subtropical South America; ii) a reduction of winter precipitation over most of the continent; and iii) reduction of precipitation in all seasons along the southern Andes.
TL;DR: The mechanism involved in biosorption resulted ion exchange between monovalent metals as counter ions present in the macrophytes biomass and heavy metal ions and protons taken up from water.
TL;DR: Patients with inappropriate therapy and/or delayed initiation of appropriate therapy had a more gradual increase in clinical pulmonary infection score than those receiving adequate therapy, and this increase was found to occur prior to the time of the clinical diagnosis.
Abstract: Inappropriate therapy (IT) and delayed initiation of appropriate therapy (DIAT) result in inadequate therapy in patients with ventilator-associated pneumonia (VAP). The aim of the current study was to assess the impact of DIAT in VAP. A total of 76 mechanically ventilated patients with bacteriologically confirmed VAP were prospectively evaluated in the intensive care unit of six hospitals in Buenos Aires, Argentina. Appropriate therapy was defined as coverage of all the identified pathogens by the antimicrobial therapy administered at the time of VAP clinical diagnosis. The clinical pulmonary infection score was measured during the 3 days before, at the onset and during the days which followed the onset of VAP. A total of 24 patients received adequate therapy; mortality was 29.2%. The remaining 52 patients received either IT (n = 16) or DIAT (n = 36); the mortality was 63.5% combined, and 75.0 and 58.3% for IT and DIAT, respectively (statistically significant compared with adequate therapy). Inappropriate therapy and delayed initiation of appropriate therapy increased the mortality of ventilator-associated pneumonia. Patients with inappropriate therapy and/or delayed initiation of appropriate therapy had a more gradual increase in clinical pulmonary infection score than those receiving adequate therapy, and this increase was found to occur prior to the time of the clinical diagnosis. In conclusion, these findings might provide the rationale for a trial of earlier initiation of therapy, based on clinical grounds in an effort to improve the outcome of patients with ventilator-associated pneumonia.
TL;DR: The stochastic analysis suggests that the southern limit of Aedes aegypti distribution in South America is close to the 15^∘C average yearly isotherm, which accounts for the historical and current distribution better than the traditional criterion of the winter (July) 10°CIsotherm.
TL;DR: It may be possible to differentiate manganese-induced parkinsonism from Parkinson's disease using clinical and imaging studies, and there appears to be a lack of response to levodopa therapy in mangane-inducedParkinsonism.
Abstract: Parkinsonism is a clinical syndrome consisting of tremor, bradykinesia, rigidity, gait, balance problems, in addition to various non-motor symptoms. There are many causes of parkinsonism such as neurodegenerative disease, drugs, vascular causes, structural lesions, infections, and toxicants. Parkinson's disease, or idiopathic parkinsonism, is the most common form of parkinsonism observed in the clinic. There is degeneration of the substantia nigra, pars compacta, which results in loss of striatal dopamine. Parkinson's disease is a slowly progressive condition in which there is a dramatic and sustained responsiveness to levodopa therapy. Manganese is an essential trace element that can be associated with neurotoxicity. Hypermanganism can occur in a variety of clinical settings. The clinical symptoms of manganese intoxication include non-specific complaints, neurobehavioral changes, parkinsonism, and dystonia. Although the globus pallidus is the main structure of damage, other basal ganglia areas can also be involved. MRI scans may show globus pallidus changes during (and for a short period after) exposure. Fluorodopa PET scans that assess the integrity of the substantia nigra dopaminergic system are abnormal in Parkinson's disease. However, these scans re-reported to be normal in a few cases studied with manganese-induced parkinsonism. The parkinsonism due to manganese may have some clinical features that occur less commonly in Parkinson's disease, such as kinetic tremor, dystonia, specific gait disturbances, and early mental, balance and speech changes. The clinical signs tend to be bilateral whereas Parkinson's disease begins on one side of the body. Patients with manganese-induced parkinsonism may be younger at the onset of the disease than with Parkinson's disease. Lastly, there appears to be a lack of response to levodopa therapy in manganese-induced parkinsonism. In summary it may be possible to differentiate manganese-induced parkinsonism from Parkinson's disease using clinical and imaging studies.
TL;DR: A critical view of findings is provided based on the principle that drought-induced changes cannot be analysed separately from the allometric changes that take place through ontogeny, as for example proposed by the widely cited hydraulic limitation hypothesis.
Abstract: The literature on whole-plant acclimation to drought is reviewed and it is proposed that leaf-level homeostasis in water status is attained during ontogeny largely thanks to whole-plant changes in physical resistance to liquid water flow caused by morphological and anatomical adjustments. It is shown that, in response to water deficits, plant resistance changes at different levels (tissue, organ, individual), levels that are correlated with the time scale of the response. It was found that such adjustments apparently tend to increase resistance to flow in the short term and to reduce it in the long term. A critical view of those findings is provided based on the principle that drought-induced changes cannot be analysed separately from the allometric changes that take place through ontogeny, as for example proposed by the widely cited hydraulic limitation hypothesis. A graphic synthetic model is presented according to which developmental responses to water deficits operate largely through reductions in wholeplant water transport capacity, combined with more or less strong reductions in leaf area (different ‘hydraulic allometries’), depending on the intrinsic tolerance of leaf tissues to partial desiccation. The model is used to show that, as the result of such adjustments, the water transport capacity per unit leaf area can decrease, remain constant, or increase, and it is argued that the expected leaf-level response would be different in each case, respectively involving a decreased, constant, or increased potential for transpiration. The article ends with a plea to collect the evidence needed to evaluate the occurrence of these three different response types across taxa and their association with different environments, including the reanalysis of existing data.
TL;DR: In this article, the authors identify pore characteristics (quantity, distribution, stability and orientation of pores) that condition water dynamics under continuous zero tillage (ZT) on silty soils of the Argentinian Rolling Pampas.
Abstract: The objective of this study was to identify pore characteristics (quantity, distribution, stability and orientation of pores) that condition water dynamics under continuous zero tillage (ZT) on silty soils of the Argentinian Rolling Pampas. Soil properties were analyzed under continuous chisel plough (CP) and ZT treatments from three trials with different duration and crop sequence. The following soil properties of A horizon were analyzed from 0 to 0.05 and from 0.10 to 0.15 m depths: bulk density, pore size distribution, pore origin distribution, aggregate stability index, infiltration rate and organic matter. Preferred pore orientation was carried out by introducing the sampling cylinders in vertical and horizontal direction and then discriminating by pore size. Total porosity of A horizon under CP was 3.5% higher than under ZT. This could be attributed to macro and mesopores as well as to structural porosity. Aggregates were 30% more stable in ZT than under CP in the top at 0.05 m due to a 21% increase in organic matter. However, infiltration rate was not improved under ZT. Under ZT, there was a tendency of macropores to become orientated in parallel to the soil surface. This horizontal preferential macropore orientation was critical in determining water infiltration. The susceptibility to stratify the structure in the first centimeters of the soil under ZT was attributed to the predominance of soybean in the crop sequence.
TL;DR: The results suggest that the density of plants may constrain the recovery of vegetation after drought, and these constraints may determine lags that limit the capacity of the ecosystem to take advantage of wet years after dry years.
Abstract: Grassland aboveground net primary production (ANPP) increases linearly with precipitation in space and time, but temporal models relating time series of ANPP and annual precipitation for single sites show lower slopes and regression coefficients than are shown by spatial models. The analysis of several ANPP time series showed lags in the ecosystem response to increased water availability, which may explain the difference between spatial and temporal models. The lags may result from constraints that ecosystems experience after drought. Our objective was to explore the structural constraints of the ANPP response to rainfall variability in a semiarid ecosystem, the Patagonian steppe, in southern Argentina. We designed a 3-yr rainfall manipulation experiment where we decreased water input with rainout shelters during two consecutive years, which included three levels of rainfall interception (30%, 55%, and 80%) and a control. In the third year, we irrigated one-half of the plots of each rainfall-interception ...
TL;DR: The ability of Gal-1 to counteract Th1-mediated responses through different, but potentially overlapping anti-inflammatory mechanisms is underscored and a possible therapeutic use of this protein is suggested for the treatment of human uveitic diseases of autoimmune etiology.
Abstract: Intraocular inflammatory diseases are a common cause of severe visual impairment and blindness. In this study, we investigated the immunoregulatory role of galectin-1 (Gal-1), an endogenous lectin found at sites of T cell activation and immune privilege, in experimental autoimmune uveitis (EAU), a Th1-mediated model of retinal disease. Treatment with rGal-1 either early or late during the course of interphotoreceptor retinoid-binding protein-induced EAU was sufficient to suppress ocular pathology, inhibit leukocyte infiltration, and counteract pathogenic Th1 cells. Administration of rGal-1 at the early or late phases of EAU ameliorated disease by skewing the uveitogenic response toward nonpathogenic Th2 or T regulatory-mediated anti-inflammatory responses. Consistently, adoptive transfer of CD4 + regulatory T cells obtained from rGal-1-treated mice prevented the development of active EAU in syngeneic recipients. In addition, increased levels of apoptosis were detected in lymph nodes from mice treated with rGal-1 during the efferent phase of the disease. Our results underscore the ability of Gal-1 to counteract Th1-mediated responses through different, but potentially overlapping anti-inflammatory mechanisms and suggest a possible therapeutic use of this protein for the treatment of human uveitic diseases of autoimmune etiology.
TL;DR: In a recovery-time series, heat-induced hypoxia and subsequent reoxygenation upon return of the fishes to 12°C led to increased protein oxidation and chemiluminescence rates within the first 12 h of recovery, resembling ischemia/reperfusion injury in mammals.
Abstract: The interplay between antioxidants, heat shock proteins and hypoxic signaling is supposed to be important for passive survival of critical temperature stress, e.g. during unfavorable conditions in hot summers. We investigated the effect of mild (18 degrees C), critical (22 degrees C) and severe (26 degrees C) experimental heat stress, assumed to induce different degrees of functional hypoxia, as well as the effect of recovery following heat stress on these parameters in liver samples of the common eelpout Zoarces viviparus. Upon heat exposure to critical and higher temperatures we found an increase in oxidative damage markers such as TBARS (thiobarbituric reactive substances) and a more oxidized cellular redox potential, combined with reduced activities of the antioxidant enzyme superoxide dismutase at 26 degrees C. Together, these point to higher oxidative stress levels during hyperthermia. In a recovery-time series, heat-induced hypoxia and subsequent reoxygenation upon return of the fishes to 12 degrees C led to increased protein oxidation and chemiluminescence rates within the first 12 h of recovery, therein resembling ischemia/reperfusion injury in mammals. HSP70 levels were found to be only slightly elevated after recovery from sub-lethal heat stress, indicating minor importance of the heat shock response in this species. The DNA binding activity of the hypoxia-inducible transcription factor (HIF-1) was elevated only during mild heat exposure (18 degrees C), but appeared impaired at more severe heat stress. We suppose that the more oxidized redox state during extreme heat may interfere with the hypoxic signaling response.