N- Homocisteinilación de proteínas plasmáticas involucradas en la red de fibrina

La hiperhomocisteinemia, concentración elevada de homocisteína (Hcy) plasmática, constituye unfactor de riesgo independiente para la enfermedad vascular. En plasma la Hcy se encuentra unida aproteínas, formando dímeros, como Hcy reducida y como homocisteína-tiolactona (HTL). La reacciónentre los grupos ε-amino de los residuos lisina de las proteínas y el grupo carbonilo de la HTL se denomina N-homocisteinilación. Este proceso alteraría la estructura y función de compuestos biológicos. En la presente tesis, los estudios realizados con plasma humano demostraron que la HTL provocó unproceso de coagulación más lento que el control. Sin embargo, las redes de fibrina obtenidas resultaronmás densas, con fibras más cortas y ramificadas, mostrando mayor resistencia a la lisis. Estosresultados sugirieron que componentes del sistema hemostático podrían ser N-homocisteinilados. En particular, se estudió el efecto de la HTL sobre albúmina, fibrinógeno, factor XIII y fibronectina. Se detectaron importantes alteraciones estructurales y funcionales en los compuestos mencionadoscomo consecuencia de la exposición a soluciones de HTL, dependientes del tiempo de tratamiento yde la concentración del tioéster. Se evidenció la N-homocisteinilación de la albúmina por el aumentodel número de grupos sulfhidrilo libres, modificando la carga neta positiva de la proteína y consecuentemente,alterando los perfiles electroforéticos obtenidos por diversas técnicas. La N-homocisteinilación del fibrinógeno produjo cambios en los procesos de formación y lisis de lafibrina similares a los observados con plasma N-homocisteinilado. Además, se demostró que la matrizde fibrina N-homocisteinilada favoreció el proceso angiogénico. La HTL provocó un aumento de laactividad de transglutaminasa del factor XIII y también de la unión de la fibronectina a fibrina. Porotro lado, se evidenció un importante efecto reductor de la HTL sobre las moléculas de fibrinógeno yfibronectina. Por lo tanto, las alteraciones mediadas por HTL detectadas en las proteínas de los sistemaspuros analizados, serían responsables de los cambios observados en el proceso de coagulacióndel sistema plasmático. Los procesos de N-homocisteinilación in vitro descriptos en la presente tesis contribuyen al esclarecimientode uno de los posibles mecanismos involucrados en la consecuencias fisiopatológicas de lahiperhomocisteinemia.Hyperhomocysteinemia, a condition characterized by high homocysteine plasma levels, is an independentrisk factor for vascular disease. Homocysteine circulates as different species, mostly proteinbound, as low-molecular-weight disulfides, as its reduced form and as the cyclic thioester homocysteine-thiolactone (HTL). N-homocysteinylation is the reaction between the carboxyl group of HTLand the epsilon-NH2 of lysine residues, with the irreversible formation of protein adducts. This reactioncould alter the structure and function of biological compounds. In the present thesis, global coagulation tests and fibrin formation assays in the presence of HTLindicated a slower coagulation process. However, HTL-associated fibrin architecture was compactand highly branched, and made up of thinner and shorter fibers than the control. These results suggestedthat hemostatic system proteins could be N-homocysteinylated. In particular, HTL effects onalbumin, fibrinogen, factor XIII and fibronectin were evaluated. Depending on HTL concentration andincubation time, the molecular structure and function of these proteins were significantly modified. Increased free thiol groups and a loss of net positive charge in N-homocysteinylated albumin weredetected, showing altered electrophoretic profiles. Fibrinogen in the presence of HTL showed impaired fibrinoformation and lysis as observed with thehomocysteinylated plasmatic system. Moreover, fibrin networks related to HTL favored the angiogenicprocess. Factor XIII transglutaminase activity and fibronectin-fibrin binding were increased by N-homocysteinylation reactions. On the other hand, an important reducing effect on fibrinogen andfibronectin molecules was observed. Therefore, the changes observed in the purified N-homocysteinylatedproteins would be responsible of the alterations detected in the plasma coagulation process. The in vitro findings of the present thesis contribute to postulate a possible mechanism involved inthe pathophysiologic consequences related to hyperhomocysteinemia.Fil: Genoud, Valeria. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Active Surveillance of Asymptomatic, Presymptomatic, and Oligosymptomatic SARS-CoV-2-Infected Individuals in Communities Inhabiting Closed or Semi-closed Institutions

Background: The high COVID-19 dissemination rate demands active surveillance to identify asymptomatic, presymptomatic, and oligosymptomatic (APO) SARS-CoV-2-infected individuals. This is of special importance in communities inhabiting closed or semi-closed institutions such as residential care homes, prisons, neuropsychiatric hospitals, etc., where risk people are in close contact. Thus, a pooling approach?where samples are mixed and tested as single pools?is an attractive strategy to rapidly detect APO-infected in these epidemiological scenarios. Materials and Methods: This study was done at different pandemic periods between May 28 and August 31 2020 in 153 closed or semi-closed institutions in the Province of Buenos Aires (Argentina). We setup pooling strategy in two stages: first a pool-testing followed by selective individual-testing according to pool results. Samples included in negative pools were presumed as negative, while samples from positive pools were re-tested individually for positives identification. Results: Sensitivity in 5-sample or 10-sample pools was adequate since only 2 Ct values were increased with regard to single tests on average. Concordance between 5-sample or 10-sample pools and individual-testing was 100% in the Ct ≤ 36. We tested 4,936 APO clinical samples in 822 pools, requiring 86?50% fewer tests in low-to-moderate prevalence settings compared to individual testing. Conclusions: By this strategy we detected three COVID-19 outbreaks at early stages in these institutions, helping to their containment and increasing the likelihood of saving lives in such places where risk groups are concentrated.Fil: Ambrosis, Nicolás Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; ArgentinaFil: Martin Aispuro, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; ArgentinaFil: Belhart, Keila. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; ArgentinaFil: Bottero, Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; ArgentinaFil: Crisp, Renée Leonor. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; ArgentinaFil: Dansey, Maria Virginia. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad de Microanálisis y Métodos Físicos en Química Orgánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Unidad de Microanálisis y Métodos Físicos en Química Orgánica; ArgentinaFil: Gabrielli, Magali. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; ArgentinaFil: Filevich, Oscar. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Genoud, Valeria. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; ArgentinaFil: Giordano, Alejandra Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; ArgentinaFil: Lin, Min Chih. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Cálculo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lodeiro, Anibal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Agrarias y Forestales; ArgentinaFil: Marceca, Felipe. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Investigaciones Matemáticas "Luis A. Santaló". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Matemáticas "Luis A. Santaló"; ArgentinaFil: Pregi, Nicolás. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Remes Lenicov, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; ArgentinaFil: Rocha Viegas, Luciana. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Rudi, Erika. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; ArgentinaFil: Solovey, Guillermo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Cálculo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Zurita, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; ArgentinaFil: Pecci, Adali. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Etchenique, Roberto Argentino. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Hozbor, Daniela Flavia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; Argentin

Simple scoring system to predict in-hospital mortality after surgery for infective endocarditis

BACKGROUND: Aspecific scoring systems are used to predict the risk of death postsurgery in patients with infective endocarditis (IE). The purpose of the present study was both to analyze the risk factors for in-hospital death, which complicates surgery for IE, and to create a mortality risk score based on the results of this analysis. METHODS AND RESULTS: Outcomes of 361 consecutive patients (mean age, 59.1\ub115.4 years) who had undergone surgery for IE in 8 European centers of cardiac surgery were recorded prospectively, and a risk factor analysis (multivariable logistic regression) for in-hospital death was performed. The discriminatory power of a new predictive scoring system was assessed with the receiver operating characteristic curve analysis. Score validation procedures were carried out. Fifty-six (15.5%) patients died postsurgery. BMI >27 kg/m2 (odds ratio [OR], 1.79; P=0.049), estimated glomerular filtration rate 55 mm Hg (OR, 1.78; P=0.032), and critical state (OR, 2.37; P=0.017) were independent predictors of in-hospital death. A scoring system was devised to predict in-hospital death postsurgery for IE (area under the receiver operating characteristic curve, 0.780; 95% CI, 0.734-0.822). The score performed better than 5 of 6 scoring systems for in-hospital death after cardiac surgery that were considered. CONCLUSIONS: A simple scoring system based on risk factors for in-hospital death was specifically created to predict mortality risk postsurgery in patients with IE

N- Homocisteinilación de proteínas plasmáticas involucradas en la red de fibrina

La hiperhomocisteinemia, concentración elevada de homocisteína (Hcy) plasmática, constituye unfactor de riesgo independiente para la enfermedad vascular. En plasma la Hcy se encuentra unida aproteínas, formando dímeros, como Hcy reducida y como homocisteína-tiolactona (HTL). La reacciónentre los grupos ε-amino de los residuos lisina de las proteínas y el grupo carbonilo de la HTL se denomina N-homocisteinilación. Este proceso alteraría la estructura y función de compuestos biológicos. En la presente tesis, los estudios realizados con plasma humano demostraron que la HTL provocó unproceso de coagulación más lento que el control. Sin embargo, las redes de fibrina obtenidas resultaronmás densas, con fibras más cortas y ramificadas, mostrando mayor resistencia a la lisis. Estosresultados sugirieron que componentes del sistema hemostático podrían ser N-homocisteinilados. En particular, se estudió el efecto de la HTL sobre albúmina, fibrinógeno, factor XIII y fibronectina. Se detectaron importantes alteraciones estructurales y funcionales en los compuestos mencionadoscomo consecuencia de la exposición a soluciones de HTL, dependientes del tiempo de tratamiento yde la concentración del tioéster. Se evidenció la N-homocisteinilación de la albúmina por el aumentodel número de grupos sulfhidrilo libres, modificando la carga neta positiva de la proteína y consecuentemente,alterando los perfiles electroforéticos obtenidos por diversas técnicas. La N-homocisteinilación del fibrinógeno produjo cambios en los procesos de formación y lisis de lafibrina similares a los observados con plasma N-homocisteinilado. Además, se demostró que la matrizde fibrina N-homocisteinilada favoreció el proceso angiogénico. La HTL provocó un aumento de laactividad de transglutaminasa del factor XIII y también de la unión de la fibronectina a fibrina. Porotro lado, se evidenció un importante efecto reductor de la HTL sobre las moléculas de fibrinógeno yfibronectina. Por lo tanto, las alteraciones mediadas por HTL detectadas en las proteínas de los sistemaspuros analizados, serían responsables de los cambios observados en el proceso de coagulacióndel sistema plasmático. Los procesos de N-homocisteinilación in vitro descriptos en la presente tesis contribuyen al esclarecimientode uno de los posibles mecanismos involucrados en la consecuencias fisiopatológicas de lahiperhomocisteinemia.Hyperhomocysteinemia, a condition characterized by high homocysteine plasma levels, is an independentrisk factor for vascular disease. Homocysteine circulates as different species, mostly proteinbound, as low-molecular-weight disulfides, as its reduced form and as the cyclic thioester homocysteine-thiolactone (HTL). N-homocysteinylation is the reaction between the carboxyl group of HTLand the epsilon-NH2 of lysine residues, with the irreversible formation of protein adducts. This reactioncould alter the structure and function of biological compounds. In the present thesis, global coagulation tests and fibrin formation assays in the presence of HTLindicated a slower coagulation process. However, HTL-associated fibrin architecture was compactand highly branched, and made up of thinner and shorter fibers than the control. These results suggestedthat hemostatic system proteins could be N-homocysteinylated. In particular, HTL effects onalbumin, fibrinogen, factor XIII and fibronectin were evaluated. Depending on HTL concentration andincubation time, the molecular structure and function of these proteins were significantly modified. Increased free thiol groups and a loss of net positive charge in N-homocysteinylated albumin weredetected, showing altered electrophoretic profiles. Fibrinogen in the presence of HTL showed impaired fibrinoformation and lysis as observed with thehomocysteinylated plasmatic system. Moreover, fibrin networks related to HTL favored the angiogenicprocess. Factor XIII transglutaminase activity and fibronectin-fibrin binding were increased by N-homocysteinylation reactions. On the other hand, an important reducing effect on fibrinogen andfibronectin molecules was observed. Therefore, the changes observed in the purified N-homocysteinylatedproteins would be responsible of the alterations detected in the plasma coagulation process. The in vitro findings of the present thesis contribute to postulate a possible mechanism involved inthe pathophysiologic consequences related to hyperhomocysteinemia.Fil: Genoud, Valeria. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Alterations of fibrin networks mediated by sulfated polysaccharides from green seaweeds

Kinetics of fibrin formation was affected by SP from Codium vermilara (Bryopsidales), Ab1 and Penicillus capitatus (Bryopsidales), PF1, showing delayed polymerization curves, in a concentration dependent manner. Increased times required for initial protofibrils formation (lag phase) and decreased maximum velocities achieved (slope) observed in our assays are related to an anticoagulant behavior. On the other hand, in the presence of increasing concentrations of each of the SP, decreases in the amount of fibrin generated were detected, denoting a reduced quantity of clotted fibrinogen, consequence of the anticoagulant action of the SP. This behavior of PF1 and Ab1 would be due to the thrombin inhibition mediated by the SP, as was mentioned above.When equal concentrations of each polysaccharide were employed in fibrin formation assays, very different results were observed. In particular, at a concentration of 5 µg/mL an important anticoagulant activity was demonstrated for PF1, but this effect was so important in the case of Ab1, that no coagulation was detected.In addition, in fibrin formation curves lower final optical densities respect to control were registered in the presence of the SP. It is well known that the final turbidity measurement is related to the weight-averaged mass per unit length (mass/length ratio) of fibrin fibers composing the clot, allowing to infer the structure of the network. The mass/length ratio proved to be lower, and consequently, gave a lower optical density value. Moreover, the delayed kinetics observed in our fibrin polymerization assays is associated to prolonged lateral aggregation times, yielding clots with few branch points and thicker fibers.In the presence of PF1 and Ab1 accelerated fibrinolysis rates were observed, mostly attributed to the reduced amount of fibrin formed. This fact is the result of diminished thrombin activity, mediated, direct or indirectly, by these SP, which induces clotting of a lesser amount of fibrinogen and consequently generates less fibrin. On the other hand, SEM showed important differences between networks. The final fibrin structure obtained in the presence of PF1 (5 μg/mL) and also in the presence of Ab1, but in this case, at a lower concentration (0.25 μg/mL), was less compact than control, composed by thicker and longer fibers. These changes in fibrin architecture could also contribute to the improved fibrinolysis observed when plasminogen was activated by rt-PA. In summary, the structural and functional features of the clots generated in the presence of PF1 and Ab1 are consequences of the anticoagulant action of these SP which, direct or indirectly, can reduce the thrombin activity. In particular, lower concentrations (expressed as mass/vol) of Ab1 than of PF1 were needed to produce similar anticoagulant effects. Our results show different characteristics of the fibrin, resulting from the action of SP, contributing to the understanding of their anticoagulant activity, and to the development of new compounds with antithrombotic therapeutic properties.Fil: Arata, Paula Ximena. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Biología Aplicada y Alimentos. Cátedra de Química de Biomoléculas; ArgentinaFil: Genoud, Valeria. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; ArgentinaFil: Lauricella, Ana Maria. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; ArgentinaFil: Ciancia, Marina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Biología Aplicada y Alimentos. Cátedra de Química de Biomoléculas; ArgentinaFil: Quintana, Irene Luisa. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentin

Extraction-free protocol combining proteinase K and heat inactivation for detection of SARS-CoV-2 by RT-qPCR

Real-time reverse transcription PCR (RT-qPCR) is the gold-standard technique for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detection in nasopharyngeal swabs specimens. The analysis by RT-qPCR usually requires a previous extraction step to obtain the purified viral RNA. Unfortunately, RNA extraction constitutes a bottleneck for early detection in many countries since it is expensive, time-consuming and depends on the availability of commercial kits. Here, we describe an extraction-free protocol for SARS-CoV-2 detection by RT-qPCR from nasopharyngeal swab clinical samples in saline solution. The method includes a treatment with proteinase K followed by heat inactivation (PK+HID method). We demonstrate that PK+HID improves the RT-qPCR performance in comparison to the heat-inactivation procedure. Moreover, we show that this extraction-free protocol can be combined with a variety of multiplexing RT-qPCR kits. The method combined with a multiplexing detection kit targeting N and ORF1ab viral genes showed a sensitivity of 0.99 and a specificity of 0.99 from the analysis of 106 positive and 106 negative clinical samples. In conclusion, PK+HID is a robust, fast and inexpensive procedure for extraction-free RT-qPCR determinations of SARS-CoV-2. The National Administration of Drugs, Foods and Medical Devices of Argentina has recently authorized the use of this method

MXene functionalized collagen biomaterials for cardiac tissue engineering driving iPSC-derived cardiomyocyte maturation

Electroconductive biomaterials are gaining significant consideration for regeneration in tissues where electrical functionality is of crucial importance, such as myocardium, neural, musculoskeletal, and bone tissue. In this work, conductive biohybrid platforms were engineered by blending collagen type I and 2D MXene (Ti3C2Tx) and afterwards covalently crosslinking; to harness the biofunctionality of the protein component and the increased stiffness and enhanced electrical conductivity (matching and even surpassing native tissues) that two-dimensional titanium carbide provides. These MXene platforms were highly biocompatible and resulted in increased proliferation and cell spreading when seeded with fibroblasts. Conversely, they limited bacterial attachment (Staphylococcus aureus) and proliferation. When neonatal rat cardiomyocytes (nrCMs) were cultured on the substrates increased spreading and viability up to day 7 were studied when compared to control collagen substrates. Human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) were seeded and stimulated using electric-field generation in a custom-made bioreactor. The combination of an electroconductive substrate with an external electrical field enhanced cell growth, and significantly increased cx43 expression. This in vitro study convincingly demonstrates the potential of this engineered conductive biohybrid platform for cardiac tissue regeneration.</p

MXene functionalized collagen biomaterials for cardiac tissue engineering driving iPSC-derived cardiomyocyte maturation

Electroconductive biomaterials are gaining significant consideration for regeneration in tissues where electrical functionality is of crucial importance, such as myocardium, neural, musculoskeletal, and bone tissue. In this work, conductive biohybrid platforms were engineered by blending collagen type I and 2D MXene (Ti3C2Tx) and afterwards covalently crosslinking; to harness the biofunctionality of the protein component and the increased stiffness and enhanced electrical conductivity (matching and even surpassing native tissues) that two-dimensional titanium carbide provides. These MXene platforms were highly biocompatible and resulted in increased proliferation and cell spreading when seeded with fibroblasts. Conversely, they limited bacterial attachment (Staphylococcus aureus) and proliferation. When neonatal rat cardiomyocytes (nrCMs) were cultured on the substrates increased spreading and viability up to day 7 were studied when compared to control collagen substrates. Human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) were seeded and stimulated using electric-field generation in a custom-made bioreactor. The combination of an electroconductive substrate with an external electrical field enhanced cell growth, and significantly increased cx43 expression. This in vitro study convincingly demonstrates the potential of this engineered conductive biohybrid platform for cardiac tissue regeneration.</p

Active Surveillance of Asymptomatic, Presymptomatic, and Oligosymptomatic SARS-CoV-2-Infected Individuals in Communities Inhabiting Closed or Semi-closed Institutions

Background: The high COVID-19 dissemination rate demands active surveillance to identify asymptomatic, presymptomatic, and oligosymptomatic (APO) SARS-CoV-2-infected individuals. This is of special importance in communities inhabiting closed or semi-closed institutions such as residential care homes, prisons, neuropsychiatric hospitals, etc., where risk people are in close contact. Thus, a pooling approach-where samples are mixed and tested as single pools-is an attractive strategy to rapidly detect APO-infected in these epidemiological scenarios. Materials and Methods: This study was done at different pandemic periods between May 28 and August 31 2020 in 153 closed or semi-closed institutions in the Province of Buenos Aires (Argentina). We setup pooling strategy in two stages: first a pool-testing followed by selective individual-testing according to pool results. Samples included in negative pools were presumed as negative, while samples from positive pools were re-tested individually for positives identification. Results: Sensitivity in 5-sample or 10-sample pools was adequate since only 2 Ct values were increased with regard to single tests on average. Concordance between 5-sample or 10-sample pools and individual-testing was 100% in the Ct ≤ 36. We tested 4,936 APO clinical samples in 822 pools, requiring 86-50% fewer tests in low-to-moderate prevalence settings compared to individual testing. Conclusions: By this strategy we detected three COVID-19 outbreaks at early stages in these institutions, helping to their containment and increasing the likelihood of saving lives in such places where risk groups are concentrated.Facultad de Ciencias ExactasInstituto de Biotecnologia y Biologia MolecularFacultad de Ciencias Agrarias y Forestale