Showing papers by "National University of La Plata published in 2022"

C-ferroptosis is an iron-dependent form of regulated cell death in cyanobacteria.

Abstract: Ferroptosis is an oxidative and iron-dependent form of regulated cell death (RCD) recently described in eukaryotic organisms like animals, plants, and parasites. Here, we report that a similar process takes place in the photosynthetic prokaryote Synechocystis sp. PCC 6803 in response to heat stress. After a heat shock, Synechocystis sp. PCC 6803 cells undergo a cell death pathway that can be suppressed by the canonical ferroptosis inhibitors, CPX, vitamin E, Fer-1, liproxstatin-1, glutathione (GSH), or ascorbic acid (AsA). Moreover, as described for eukaryotic ferroptosis, this pathway is characterized by an early depletion of the antioxidants GSH and AsA, and by lipid peroxidation. These results indicate that all of the hallmarks described for eukaryotic ferroptosis are conserved in photosynthetic prokaryotes and suggest that ferroptosis might be an ancient cell death program.

Highly sensitive urine glucose detection with graphene field-effect transistors functionalized with electropolymerized nanofilms

Abstract: We introduce a new approach for glucose oxidase (GOx) immobilization on graphene field-effect transistors (gFETs) to fabricate highly sensitive glucose sensors. The strategy relies on the electropolymerization of a layer of the copolymer poly(3-amino-benzylamine-co-aniline) (PABA) on graphene-based transistors. The synthesized polymer film provides the suitable electrostatic charge and non-denaturing environment for enzyme immobilization without the need of any chemical primer. Then, the local pH changes triggered by the enzyme-catalyzed oxidation produce a shift in the Dirac potential of the gFETs to more negative values, which is evidenced by the differences in the graphene channel conductivity and constitutes the signal transduction mechanism of the sensing devices. The assembled biosensors revealed a low LOD of 4.1 μM and were capable of detecting glucose in the range from 10 to 1000 μM in a flow configuration. Moreover, they showed sensitivity of −24.9 μA per decade of glucose concentration and a fast response time, with an average value of 190 seconds, while allowing the operation at small gate-source and drain-source voltages. Finally, the biosensors were able to successfully monitor the analyte in urine samples, showing their potential towards the fabrication of point-of-care glucose testing devices.

Perspectivas docentes para una agenda crítica en educación mediática post COVID-19. Estudio comparativo en Latinoamérica

Abstract: La pandemia causada por la COVID-19 en America Latina obligo a transitar de un modelo educativo presencial a uno a distancia atravesado por la emergencia, las precariedades tecnologicas y la falta de planificacion. Esto ha agudizado las necesidades de educacion mediatica en la region. En ese contexto, se analizo los cambios ocurridos para proponer una agenda critica desde la perspectiva de los docentes. En primer lugar, se realizo una revision documental de fuentes oficiales para conocer las estrategias de los cuatro paises de estudio: Argentina, Ecuador, Chile y Peru. En segundo lugar, se llevaron a cabo ocho grupos focales con docentes de primaria de instituciones publicas y privadas para conocer su percepcion sobre sus competencias mediaticas y las de sus estudiantes, el impacto de la pandemia en sus practicas y necesidades, y los retos emergentes en esta crisis. Los resultados apuntan a la necesidad de capacitaciones pertinentes en el manejo de las TIC, asi como estrategias que atiendan las brechas de conectividad, la falta de ambientes adecuados y la sobrecarga laboral. Los resultados especificos por pais, las diferencias y demandas propias de cada contexto, se discuten en este trabajo como aportes al desarrollo de una agenda critica en educacion mediatica.

The Entomopathogenic Fungus Beauveria bassiana Shows Its Toxic Side within Insects: Expression of Genes Encoding Secondary Metabolites during Pathogenesis

Abstract: Entomopathogenic fungi are extensively used for the control of insect pests worldwide. Among them, Beauveria bassiana (Ascomycota: Hypocreales) produce a plethora of toxic secondary metabolites that either facilitate fungal invasion or act as immunosuppressive compounds. These toxins have different chemical natures, such as nonribosomal peptides and polyketides. Even though their precise role is poorly understood, they are usually linked to virulence. These fungal secondary metabolites are produced by the expression of gene clusters encoding the various proteins needed for their biosynthesis. Each cluster includes synthetases for nonribosomal peptides (NRPS), polyketides (PKS), or hybrid NRPS-PKS genes. The aim of this review is to summarize the information available from transcriptomics and quantitative PCR studies related to the expression of B. bassiana NRPS and PKS genes inside different insects as the infection progresses; as for the host immune response, to help understand the mechanisms that these toxins trigger as virulence factors, antimicrobials, or immunosuppressives within the context of a fungus-insect interaction.

Nonlinear micro finite element models based on digital volume correlation measurements predict early microdamage in newly formed bone

Abstract: Bone regeneration in critical-sized defects is a clinical challenge, with biomaterials under constant development aiming at enhancing the natural bone healing process. The delivery of bone morphogenetic proteins (BMPs) in appropriate carriers represents a promising strategy for bone defect treatment but optimisation of the spatial-temporal release is still needed for the regeneration of bone with biological, structural, and mechanical properties comparable to the native tissue. Nonlinear micro finite element (μFE) models can address some of these challenges by providing a tool able to predict the biomechanical strength and microdamage onset in newly formed bone when subjected to physiological or supraphysiological loads. Yet, these models need to be validated against experimental data. In this study, experimental local displacements in newly formed bone induced by osteoinductive biomaterials subjected to in situ X-ray computed tomography compression in the apparent elastic regime and measured using digital volume correlation (DVC) were used to validate μFE models. Displacement predictions from homogeneous linear μFE models were highly correlated to DVC-measured local displacements, while tissue heterogeneity capturing mineralisation differences showed negligible effects. Nonlinear μFE models improved the correlation and showed that tissue microdamage occurs at low apparent strains. Microdamage seemed to occur next to large cavities or in biomaterial-induced thin trabeculae, independent of the mineralisation. While localisation of plastic strain accumulation was similar, the amount of damage accumulated in these locations was slightly higher when including material heterogeneity. These results demonstrate the ability of the nonlinear μFE model to capture local microdamage in newly formed bone tissue and can be exploited to improve the current understanding of healing bone and mechanical competence. This will ultimately aid the development of BMPs delivery systems for bone defect treatment able to regenerate bone with optimal biological, mechanical, and structural properties.

Identification and in silico study of a novel dipeptidyl peptidase IV inhibitory peptide derived from green seaweed Ulva spp. hydrolysates

Abstract: A number of functional foods containing seaweed-derived peptides are currently commercialized. Some seaweed derived peptide-containing products include Wakame peptide® and Nori peptide S®. To develop functional foods with the addition of Ulva spp. peptides, the isolation and identification of dipeptidyl peptidase IV (DPP-IV) inhibitory peptides from hydrolysates of this seaweed was performed. Ulva spp. peptides were fractionated and purified sequentially by anion exchange, ultrafiltration, and reversed phase high performance liquid chromatography. The fractions obtained from each analytical step were collected and the in vitro enzyme inhibitory activity was evaluated. The applied purification process increased the in vitro DPP-IV inhibitory activity. The inhibition mechanism of DPP-IV of the most active fraction was evaluated and it was analyzed by MALDI-TOF. A peptide SLAVSVH was identified. It has 57% of hydrophobic residues in their sequence (including Ala and branched chain amino acids), which could be a common feature among inhibitory peptides of DPP-IV. Molecular docking analysis showed that SLAVSVH/DPP-IV complex was stabilized by CH–π interactions between the side chains of Val6 with the indol of Trp629, and between rings of His7 with Trp563. The energy values obtained for the peptide under study indicate that it is a good candidate to inhibit DPP-IV.

Longitudinal assessment of personal air pollution clouds in ten home and office environments

Abstract: Elevated exposure to indoor air pollution is associated with negative human health and well-being outcomes. Inhalation exposure studies commonly rely on stationary monitors in combination with human time-activity patterns; however, this method is susceptible to exposure misclassification. We tracked ten participants during five consecutive workdays with stationary air pollutant monitors at their homes and offices, and wearable personal monitors. Real-time measures of size-resolved particulate matter (within range 0.3-10 μm) and CO2 , and integrated samples of PM10 , VOCs, and aldehydes were collected. The PM10 cloud magnitude (excess of PM10 beyond stationary room concentration) was detected for all participants in homes and offices. The PM10 cloud magnitude ranged within 5-37 μg/m3 and was the most discernible in the coarse particle size fraction. Particles associated with "Urban mix," "Traffic," and "Human activities" sources contributed the most to PM10 exposures. The personal CO2 clouds were detected for participants with the SEMs in their living rooms and private or low-occupancy offices. The stationary monitors placed in bedrooms were better predictors of personal PM10 and CO2 exposures. An overall of 33 VOCs and aldehydes were detected in both microenvironments, with the majority exhibiting high correlation between personal and stationary stations.

Redox flow battery time‐varying parameter estimation based on high‐order sliding mode differentiators

Abstract: A new insight into vanadium redox flow batteries (VRFB) parameter estimation is presented. Driven by the electric vehicles proliferation, a hybrid fast-charging station with grid and a renewable energy connection is particularly considered. In this stationary application, the VRFB is operating as buffering module. This hybrid topology could contribute to reduce the grid connection cost of the charging station. However, to make VRFB a viable technology, improvements are needed. Among these, some of the most important are in the field of the estimation of the battery's State of Charge, State of Health, and internal parameters. The proposed estimation method is based on a recursive least square (RLS) estimation algorithm with forgetting factor, combined with a sliding mode finite-time convergent differentiation algorithm. The latter provides robust exact derivatives of both VRFB's current and voltage with a high degree of noise rejection, required by the RLS algorithm to perform a precise estimation. The proposed sliding mode-based estimation setup is completed with a systematic methodology to guarantee the validity of the on-line estimated values, depending on the persistence of excitation of the measured current and voltage. Finally, the methodology is thoroughly analysed and validated by computer simulation.

Timing of convalescent plasma administration and 28-day mortality in COVID-19 pneumonia

Abstract: This is a multicenter cohort study including consecutive, hospitalized patients ≥18 years, with moderate to severe COVID-19, carried out to evaluate the relationship between the timing of convalescent plasma administration and 28-day mortality. Data were prospectively collected between May 14, 2020 and October 31, 2020. Patients were grouped according to the timing of administration of convalescent plasma as <3 days, between 3 and 7 days, and >7 days. The main outcome variable was 28-day mortality. Independent predictors of mortality were identified by logistic regression. Of 4719 patients receiving convalescent plasma, 3036 (64.3%) were in the general ward, 1171 (24.8%) in the intensive care unit (ICU), and 512 (10.8%) in the ICU on mechanical ventilation. Convalescent plasma was administered to 3113 (66%) patients within the first 3 days of hospital admission, to 1380 (29.2%) between 3 and 7 days, and to 226 after 7 days; 28-day mortality was, respectively, 18.1%, 30.4% and 38.9% (p<0.001). In the regression model, convalescent plasma administration within the first 3 days of admission was associated with reduced 28-day mortality, compared with the administration after 7 days (OR 0.40, 95% CI 0.30 to 0.53). Early convalescent plasma administration was associated to a significant decreased mortality in patients in the general ward (OR 0.45, 95% CI 0.29 to 0.69) and in the ICU (OR 0.35, 95% CI 0.19 to 0.64), but not in those requiring mechanical ventilation (OR 0.52, 95% CI 0.27 to 1.01). In conclusion, this study suggests that early administration of convalescent plasma to patients with COVID-19 pneumonia is critical to obtain therapeutic benefit.

On the empirical content of the convergence debate: Cross‐country evidence on growth and capacity utilisation

Abstract: The Neo-Kaleckian model predicts that actual capacity utilisation is endogenous to demand shocks and positively correlated with growth in the short and long run. Competing macroeconomic theories predict that such correlation does not exist in the long run and demand shocks have transitory effects on capacity utilisation. Using a quarterly unbalanced panel of 21 developed and developing countries, we show that taking into account direct survey measures, capacity utilisation is stationary, positively correlated with growth in the short run and uncorrelated with growth in the long run. These results are inconsistent with the long-run behaviour of the Neo-Kaleckian model.

Drug Repurposing

Abstract: Drug repurposing involves exploring new medical uses for existing drugs, including approved, discontinued, shelved and investigational therapeutics. As the new indication is built on already available safety, pharmacokinetic and manufacturing data, drug repurposing represents an expedited way to develop innovative medications, and has found especial interest in the fields of rare and neglected conditions. It is estimated that about one third of recent approvals correspond to repurposing examples, and different public initiatives have been launched to foster the exploration of repurposing opportunities. The present chapter reviews classical and recent examples of off-label use, drug rescue and drug repositioning at different stages of the drug development process, from sildenafil to aspirin, from thalidomide to adalimumab, among many others. It also discusses challenges and opportunities of drug repurposing, from commercial and legal obstacles to expansion of the drug repurposing horizons in the context of precision medicine and polypharmacology. At last, modern approximations to explore repurposing prospects in a systematic manner are summarized.