Universidad de la República de Uruguay
Recent publications
The use of macroinvertebrates as indicators of water quality is an effective and low-cost tool, which is widely implemented in biomonitoring programmes. Certain taxa are characteristic of impaired watercourses (e.g. Oligochaeta, Chironomidae and Amphipoda), while others are characteristic of good-quality watercourses (e.g. Ephemeroptera, Plecoptera and Trichoptera; EPT). In this work, we evaluated the response of the macroinvertebrate assemblages to different land uses. For this purpose, artificial substrate colonization experiments were conducted in streams including urban (U, n = 3), intensive agriculture and dairy production (AD, n = 4) and extensive cattle ranching (CR, n = 4) land uses. Because in Uruguay pristine ecosystems are practically non-existent and streams of low order streams associated with extensive cattle production represent the lowest deterioration water quality condition, CR sites were used as control reference streams. Physicochemical water parameters were measured. For macroinvertebrate sampling, 10 artificial substrates were installed in each stream. A total of 110 artificial substrates were analysed. Each sample/site consisted of a plastic mesh bag of 1.2 cm opening, which were filled with 160 cm³ (including 73.3 ± 5.8 cm³ interstitial water) of stones sieved between 1.3 and 1.5 cm. During the summer of 2018 (February), devices were left in streams for 15 days for communities to colonize them. U and AD land use represented the stressors with the highest impact on the attributes and composition of the macroinvertebrate communities. Abundance of EPT was higher in CR, meanwhile Caenogastropoda dominated in AD, and Amphipoda in U sites. Macroinvertebrate groups to order level classification were able to effectively discriminate between different land uses. The use of artificial substrate also demonstrated to be efficient method for monitoring macroinvertebrate community. We did not find a correlation between the physicochemical water parameters and the macroinvertebrate community. In this context, we propose a rapid and cost-effective biomonitoring approach, capable of estimating the degree of impact of different land uses. © 2022 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
Purpose To evaluate the possibility to access the anatomic femoral insertion of the anterior cruciate ligament (ACL) through trans-tibial (TT) and trans-portal technique, for ACL reconstruction in an independent way. To register anatomical characteristics of the TT tunnels. Methods Ten formaldehyde preserved knee anatomic articular specimens were dissected. Femoral tunnels were confectioned reproducing the original topography of the ACL. First, the femoral tunnel was made with the independent trans-portal technique. Then, utilizing the tibial stump of the ACL and tibial guides at 45°, the TT tunnels were confectioned trying to match the previously made femoral tunnel by trans-portal technique. Results In all specimens, match between the TT tunnel with the independent trans-portal tunnel was achieved. Mean values for TT coronal angle was 53,0°, for transversal angle 43,3° and for distance from tunnel to joint line 2,55 cm. A horizontalization and medialization of the TT tunnels had to be made to adequately match with the femoral tunnel made by the independent trans-portal technique. Conclusions By macroscopic anatomic and independent means, an anatomic femoral tunnel was confectioned with the TT technique matching with the anatomic femoral tunnel made in an independent way. As clinical relevance, the present study allows to anatomically assess the possibility to perform an anatomic femoral tunnel through the TT technique. Level of evidence V
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive death of motor neurons and muscle atrophy, with defective neuron-glia interplay and emergence of aberrant glial phenotypes having a role in disease pathology. Here, we have studied if the pigment violacein with several reported protective/antiproliferative properties may control highly neurotoxic astrocytes (AbAs) obtained from spinal cord cultures of symptomatic hSOD1G93A rats, and if it could be neuroprotective in this ALS experimental model. At concentrations lower than those reported as protective, violacein selectively killed aberrant astrocytes. Treatment of hSOD1G93A rats with doses equivalent to the concentrations that killed AbAs caused a marginally significant delay in survival, partially preserved the body weight and soleus muscle mass and improved the integrity of the neuromuscular junction. Reduced motor neuron death and glial reactivity was also found and likely related to decreased inflammation and matrix metalloproteinase-2 and -9. Thus, in spite that new experimental designs aimed at extending the lifespan of hSOD1G93A rats are needed, improvements observed upon violacein treatment suggest a significant therapeutic potential that deserves further studies.
Broccoli heads are typically packaged and marketed in petroleum-based heat-shrinkable or stretch-cling films that are not biodegradables. These types of films are not compatible with global strategies to reduce plastics waste. One of these strategies is development of biodegradable packaging materials that can be used as an alternative food package. Therefore, a biodegradable stretch-cling film, based on poly(butylene-adipate-co-terephthalate) and poly(lactide) blend (Nature Fresh®), for its application in broccoli head packaging has been studied. To determine suitability of Nature Fresh® film for broccoli packaging, broccoli heads were wrapped in this film and stored at 2°C for 35 d. Broccolis without packaging and wrapped in linear low density polyethylene (LLDPE) were used as controls. Physicochemical and sensory evaluation were determined during storage to study the effect of films on quality and shelf life of broccoli. On the one hand, broccolis packaged in Nature Fresh® and LLDPE presented similar evolution in internal atmosphere composition, color, hydroxycinnamic acids and carotenoids content and overall appearance. On the other hand, weight loss and decrease in firmness were significantly higher in broccoli wrapped in Nature Fresh® compared to LLDPE, but this had no impact on overall appearance. Nature Fresh® extended postharvest storage of broccoli heads at least 21 d at 2ºC, which is an adequate time to market. In conclusion, Nature Fresh® film was a viable packaging alternative to LLDPE to preserve broccoli quality during postharvest storage, while fulfilling global strategies to reduce plastics waste.
Real-world networks show community structures – groups of nodes that are densely intra-connected and sparsely inter-connected to other groups. Nevertheless, Community Detection (CD) is non-trivial, since identifying these groups of nodes according to their local connectivity can hold many plausible solutions, leading to the creation of different methods. In particular, CD has recently been achieved by Force-Directed Algorithms (FDAs), which originally were designed as a way to visualize networks. FDAs map the network nodes as particles in a D-dimensional space that are affected by forces acting in accordance to the connectivity. However, the literature on FDA-based methods for CD has grown in parallel from the classical methods, leaving several open questions, such as how accurately FDAs can recover communities compared to classical methods. In this work, we start to fill these gaps by evaluating different numerical implementations of 5 FDA methods and different clustering analyses on state-of-the-art network benchmarks – including networks with or without weights and networks with a hierarchical organisation. We also compare these results with 8, well-known, classical CD methods. Our findings show that FDA methods can achieve higher accuracy than classical methods, albeit their effectiveness depends on the chosen setting – with optimisation techniques leading over numerical integration and distance-based clustering algorithms leading over density-based ones. Overall, our work provides detailed information for any researcher aiming to apply FDAs for community detection.
Electrification of the light-duty vehicle (LDV) fleet in the United States (U.S.) decreases the long-term demand for maize ethanol. This analysis assesses the consequences of accelerated penetration of electric vehicles into the U.S. LDV fleet on global food production, prices, land-use, and carbon emissions. Population and income growth are framed around Shared Socioeconomic Pathways (SSP). The scenarios progressively increase the 2050 sales share of electric LDVs to 100%. The results indicate a maximum price decline of 9.5% for maize and a significant increase in U.S. maize exports. The fleet electrification also leads to a decline in global cropland compared to the baseline by up to 4.4 million hectares at the end of the projection period. Mean GHG reductions in the 100% LDV sales scenario range from 39.4% to 52.0% of 2019 emissions from gasoline LDVs depending on the SSP. Thus, transportation policies supporting additional electric vehicles reduce food prices and carbon emissions.
The study of information and communications technology (ICT) adoption signals that diffusion processes within highly unequal societies produce stratification in the access to digital technologies and thus, maintain or even increase previous socioeconomic disparities. While technological utopians believed that One Laptop Per Child (OLPC)-like programs could reduce societal inequalities, the economics literature evaluating these initiatives has mostly focused on student's human capital. Results suggest no impact, even for successful programs such as Uruguay's own OLPC-inspired Plan Ceibal. In this paper, we use an event-study approach to difference-indifferences to identify the impact of Plan Ceibal on the household adoption of technological goods across income quintiles. Our results show that Plan Ceibal helped to bridge domestic digital disparities in terms of access to PC and favored the uptake of internet services. We discuss the potential mechanisms behind these results. Regarding household PC access, even though Plan Ceibal was conceived as a universal program targeting primary-level students attending public schools, both infantilization of poverty and a dual-system educational stratification may explain why this initiative had a heterogenous impact across different income groups. Regarding household connectivity, Plan Ceibal reduced the cost of the bundle required to consume internet services at the time of the study, improving affordability and access among households with beneficiaries of the program.
Background Elevated Lipoprotein(a) [Lp(a)] is independently associated with increased cardiovascular disease (CVD) risk. There are discrepancies regarding its epidemiology due to great variability in different populations. This study aimed to evaluate the prevalence of elevated Lp(a) in people with moderate CVD risk and increased LDL-c and to determine the association between family history of premature CVD and elevated Lp(a). Methods Random subjects from the CESCAS population-based study of people with moderate CVD risk (Framingham score 10–20 %) and LDL-c ≥ 130 mg/dL, were selected to evaluate Lp(a) by immunoturbidimetry independent of the Isoforms variability. The association between family history of premature CVD and elevated Lp(a) was evaluated using multivariate logistic regression models. Elevated Lp(a) was defined as Lp(a) ≥ 125 nmol/L. Results Lp(a) was evaluated in 484 samples; men = 39.5 %, median age = 57 years (Q1-Q3: 50–63), mean CVD risk = 14.4 % (SE: 0.2), family history of premature CVD = 11.2 %, Lp(a) median of 21 nmol/L (Q1-Q3: 9–42 nmol/L), high Lp(a) = 6.1 % (95 % CI = 3.8–9.6). Association between family history of premature CVD and elevated Lp(a) in total population: OR 1.31 (95 % CI = 0.4, 4.2) p = 0.642; in subgroup of people with LDL-c ≥ 160 mg%, OR 4.24 (95 % CI = 1.2, 15.1) p = 0.026. Conclusions In general population with moderate CVD risk and elevated LDL-c from the Southern Cone of Latin America, less than one over ten people had elevated Lp(a). Family history of premature CVD was significantly associated with the presence of elevated Lp(a) in people with LDL-c ≥ 160 mg/dL.
To assess how sandy beach biodiversity is influenced by the effects of environmental features and urbanization, we sampled the macrofauna in the whole across-shore gradient of 90 beach sites in Southeast Brazil. We found that morphodynamic features were the main drivers of macrobenthos, but urbanization-related variables, such as number of beachgoers and number of constructions on the upper shore, decreased species richness and biomass. We also found that submerged zones sustained the highest number of species and biomass in the across-shore gradient, but were the most impacted by human activities. By demonstrating the ecological importance of submerged zones, our results show that beach management practices, which are mainly focused on the upper shore, are missing important components of beach biodiversity. To secure the sustainability of beach ecosystems, management initiatives should include both their social and ecological components and consider the entire Littoral Active Zone as the proper management unit.
Cancer and cardiovascular diseases are the main causes of death in Uruguay and developed countries. In clinical practice, there is often the need to administrate chemotherapy with cisplatin (CTP) to patients with cardiovascular comorbidities. The aim of this work is to characterize the possible detrimental effects in cardiac function by the acute exposition to CPT using isolated heart and cardiomyocytes from guinea pigs (Cavia porcellus). All the procedures regarding animal experimentation were performed following approved protocols by the university ethics committee. Isolated hearts were placed in a Langendorff system and perfused with Tyrode 1.8 mM Ca2+ as control medium, or with extracellularly added CPT (0–100 µM). Tension was recorded with a gauge force transducer attached to the papillary muscle and electrical responses were measured with Ag-AgCl electrodes placed in surface extremes near the papillary muscle. Cardiomyocytes were isolated by enzymatic methods. Data were obtained by patch clamp and confocal microscopy with Rhodamine and Fluo dyes sensitive to Ca2+ binding. Non-parametric t tests were used for data comparison. The best fit of Hill’s equation to dose–response curves was done using nonlinear regression methods. In isolated hearts, CPT showed a biphasic effect over the development of tension, increasing up to 5–10 µM to decrease at higher concentrations. In isolated cardiomyocytes, Ca2+ currents were stimulated and inhibited by CPT in a similar dose. Confocal microscopy showed an increment and a reduction of relative fluorescence of the calcium-sensitive dyes with CPT as well. Our results suggest that CPT may affect cardiac contraction and automatism upon acute exposure of the heart, presumably by blocking L-type (Cav1.2) calcium channels and interference with molecules involved in maintaining the homeostasis of intracellular Ca2+.
Cropland expansion has been occurring over the last century, especially in South America, displacing non-crop areas mainly with soybean. Changes at a landscape level were followed by changes at a local scale, such as the adoption of insect-resistant transgenic crops. The homogenization of agroecosystem composition and agronomic practices have a great impact on arthropod predators and herbivore insects, which has not been quantified to a great extent in South America. We evaluate the effects of cover composition (1 km radii) as a landscape variable, and Bt adoption as a local variable on the quantity of the main predators and pests in soybean fields in Uruguay. Over a two-year period, we sampled 60 soybean fields with sweep net and beating sheet. We found that Bt and non-Bt soybean fields did not differ in the number of predators and stink bugs, while Bt fields were associated with less caterpillars’ abundance. The proportion area of soybean negatively affected the quantity of some predators in this crop. In contrast, the landscape cover with natural grassland, commercial forest and maize positively affected some of these beneficial organisms. The number of stink bugs in soybean was highly affected by the surrounding cover composition. Arthropod responses depend on soybean’s phenological period. We demonstrate the effects of the agriculturalization process on soybean predators and pests, suggesting that Bt adoption does not affect predators and each vegetation cover impacts them differentially. Different non-crop landscape cover and the abundance of predators in the field margin are positively associated with the abundance of predators in soybean fields.
In running waters, the concentration of components that define water quality can be subjected to ample fluctuations quantitatively linked to flow rate. If not properly considered, such variability may hinder assessment of the evolution of water quality, of the effects of management actions, and ultimately the understanding of processes driving water quality. The functional response to flow rate was characterized for multiple biogeochemical variables in a pristine, low order stream. Variability of responses spanned between a factor of 2 and > 34, and in all cases were associated to flow rate according to one of three patterns: positive asymptotic (for variables: seston, suspended particles, total nutrients, dissolved and particulated organic matter, dissolved inorganic nitrogen), negative asymptotic (conductivity and dissolved reactive silicon), and humped (dissolved inorganic phosphorous). Building on those results, a rationale is presented for an unambiguous, cost-effective approach to water quality evaluation in running systems with predominantly diffuse sources.
Examination failure rate is high in veterinary anatomy in Brazilian universities. We report here our active learning experience in which students recorded video reports on veterinary anatomical specimens of locomotor apparatus to support classic learning. Eighteen students were divided into 2 groups, case group (V3) and control (E). Case group students individually recorded video reports of prosected specimens weekly. Acceptance and efficacy of the strategy were assessed with a Likert scale anonymous questionnaire and students' scores in theoretical exams. The method was highly accepted and the performance test proved that recording videos is an effective strategy for active learning in anatomy.
Quillaja saponins have an intrinsic capacity to interact with membrane lipids that self-assembles in nanoparticles (immunostimulating complexes or ISCOM-matrices) with outstanding immunoadjuvant activity and low toxicity profile. However, the expensive and laborious purification processes applied to purify Quillaja saponins used to assemble ISCOM-matrices show an important drawback in the large-scale use of this vaccine adjuvant. Thus, in this study, we describe a protocol to appropriately formulate ISCOM-matrices using the raw aqueous extract (AE) of Quillaja lancifolia leaves. In the presence of lipids, AE was able to self-assemble in nanostructures that resembles immunostimulating complexes (ISCOM). These negatively charged nanoparticles of approximately 40 nm were characterized by transmission electron microscopy and dynamic light scattering. In addition, well-known saponins with remarkable immunoadjuvant activity, as QS-21, were detected into nanoparticles. Thus, the easier, robust, cheaper, and environmentally friendly method developed here may be an alternative to the classical methods for ISCOM-matrices production that use high-purified saponins. Graphical abstract
One‐dimensional systems of titanium dioxide and titanates are interesting for the fundamental study of physical and chemical properties at the nanoscale. In this work we present the electronic structure, mechanical and optical properties of angstrom scale titanate derived nanowires (ASW) by means of density functional theory (DFT) and Density Functional based Tight Binding (DFTB). This one‐dimensional H2TiO3 nanostructure is an interesting real material that could serve for understanding, at a fundamental level, the physical properties of TiO5 concatenated polyhedrons derived from hydrogen titanates. The proposed structural model demonstrates to be locally stable according to phonon analysis, and it can be inferred that the one‐dimension structure is essentially preserved. The mechanical properties put this nanowire as a flexible material, that could be used in flexible substrates maintaining its electronic properties. Also, the capacity of this system to be sensitized with a catechol dye was explored. For this porpoise, the adsorption of the catechol molecule was tested showing that the most stable interaction corresponds to a dissociative chelate configuration. Finally, it was possible to verify the capability of the sensitized system for injecting electrons from the catechol dye to the nanowire under visible light exposure. Thus, we present these extreme one‐dimensional nanostructured materials as candidates for solar cell applications. In this work the electronic structure, mechanical and optical properties of angstrom scale titanate derived nanowires (ASW) H2TiO3 are investigated by means of DFT and DFTB. Additionally, the interaction between this extremely low dimensional semiconductor structure and a catechol molecule acting as a dye is studied, showing the capability of sensation under visible light illumination.
Many studies have shown that biodiversity regulates a multitude of ecological functions that are needed to maintain the productivity and efficiency of a variety of types of ecosystems. What is not known is how human activities may change the ‘multifunctionality’ of ecosystems as they have both direct impacts on ecosystems and indirect effects on the biodiversity that serves to control ecological functions. Using a database on hundreds of lakes spanning four large neotropical wetlands, we demonstrate that species richness and the functional diversity of fish, macrophytes, microcrustaceans, rotifers, protists, and phytoplankton are positively associated with ecosystem multifunctionality, including nutrient concentrations, standing biomass, and ecosystem metabolism. However, we also found that the relationship between biodiversity and multifunctionality is weakened by human pressures and that part of this impact occurs through changes in biodiversity. Our results suggest that human activities may break down the biological controls needed to maintain the suite of ecosystem functions that sustain wetlands.
The South American Dipole (SAD) is the main mode of rainfall variability at the intrasesasonal time-scale in South America. Its phases, determined by wet/dry conditions over the SACZ and SESA regions, have been related to extreme precipitation and droughts across South America, but are yet to be fully understood and predicted. In this work, we study the intraseasonal predictability of the SAD in relation with the Madden-Julian Oscillation (MJO) in the DJFM season. We show that significant predictability windows for the SAD’s extreme states emerge up to 10-20 days after the MJO is found in phase 2. In particular, we introduce a classification of MJO trajectories based on the RMM index, defining Long and Intense ( LIT ) and Not Long and Intense ( NLIT ) sets of trajectories. These sets bear resemblance to MJO events that are able or unable to propagate beyond the Maritime Continent, respectively. Moreover, we show that they influence differently over the SAD’s predictability. While both sets present similar tropical-extratropical teleconnections, the LIT set presents a more intense and persistence tropical-tropical teleconnection. Because of this, there is a set-independent predictability for the SESA region, influenced by both tropical and extratropical teleconnections, and a LIT dependency for the SACZ predictability, influenced mainly by the presence of the tropical-tropical teleconnection. Overall, our work contributes to the intraseasonal predictability of SAD phases and understanding its relationship with MJO events.
Transforming lignocellulosic biomass into C5 and C6 sugars suitable to produce biofuels, building blocks, and high-value-added compounds is a key aspect of sustainable strategies and is central to the biorefinery concept. Xylan is found acetylated and bound to cellulose and lignin forming an insoluble complex in nature, and its degradation involves a collection of enzymes acting together. To gain a better understanding of this process, the present study focuses on the elucidation of the main products resulting from the hydrolysis of delignified Eucalyptus dunnii bark by an enzymatic extract from Pseudozyma sp. with xylanase and acetylxylan esterase activities but no cellulase activity. Scanning electron microscopy (SEM) studies of the insoluble fraction after hydrolysis revealed cracking on the surface of the material. The enzymatic activity of the crude yeast extract was evidenced by TLC and HPLC analysis of the hydrolysate, which allowed us to detect xylose, acetylxylobiose, and acetic acid. Finally, the principal low molecular weight products obtained from this process were characterized by nuclear magnetic resonance (NMR) spectroscopy as xylose and 3-O-acetylxylobiose. Based on these spectroscopic and chromatographic results, it was possible to estimate a 4:1 ratio of xylose to 3-O-acetylxylobiose. These results highlight the importance of using an enzymatic system for effective xylan degradation.
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4,272 members
Adriana Esteves
  • Departamento de Bioquímica
Dario Caffarena
  • Salud de los Rumiantes
Federico García Suárez
  • Departamento de Ciencias Sociales (Facultad de Agronomía)
Horacio Heinzen
  • Facultad de Química
Maximo Rossi
  • Departamento de Economía (Facultad de Ciencias Económicas y de Administración)
Av. 18 de Julio 1824-1850, 11200 Montevideo, Montevideo, Uruguay
Head of institution
Rodrigo Arim
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