Trombosis de senos venosos cerebrales una manifestación extrapulmonar de COVID-19: Reporte de caso / Cerebral venous sinus thrombosis, an extrapulmonary manifestation of COVID-19: A case report

Resumen La trombosis de senos venosos cerebrales es un evento infrecuente en la población pediátrica y sus manifestaciones clínicas pueden variar dependiendo de la localización y extensión de la lesión, etiología o grupo etario (1); así mismo, la asociación de esta patología con virus es poco común, sin embargo, se han repor tado casos de trombosis de senos venosos en pacientes adultos con SARS-CoV-2 en relación con los mecanismos de lesión endotelial y respuesta inflamatoria que desencadena mecanismos procoagulantes. A continuación se presenta el primer caso reportado en Colombia de un caso de trombosis venosa cerebral en un lactante previamente sano, que debuta con un cuadro infeccioso gastrointestinal que resuelve y una semana después se presenta con cefalea y paralisis del VI par craneal derecho. Se documentó por angioto mografía trombosis del seno venoso sagital con extensión a senos transversos; los laboratorios fueron negativos para otras causas sistémicas y con prueba de anticuerpos para coronavirus positiva.

Abstract Cerebral venous sinus thrombosis is infrequent in the pediatric population and its clinical manifestations may vary depending on the anatomical location and the extent of the lesion, etiology or age group(1). The association of this pathology with viruses is uncommon, however, cases in adults with SARS-Cov2 have been reported triggered by procoagulant mechanisms due to endothelial injury and inflammatory response. The following article is the first reported case in Colombia of cerebral venous thrombosis in a previously healthy child, who debuted with gastrointestinal infectious disease and a week later with headache and sixth right cranial nerve palsy . The diagnosis of sagittal venous sinus thrombosis with extension to transverse sinuses was documented in a computed tomography angiography; laboratories for systemic diseases were negative and antibodies for coronavirus were positive.

Gelatin-Graphene Oxide Nanocomposite Hydrogels for Kluyveromyces lactis Encapsulation: Potential Applications in Probiotics and Bioreactor Packings.

Nutraceutical formulations based on probiotic microorganisms have gained significant attention over the past decade due to their beneficial properties on human health. Yeasts offer some advantages over other probiotic organisms, such as immunomodulatory properties, anticancer effects and effective suppression of pathogens. However, one of the main challenges for their oral administration is ensuring that cell viability remains high enough for a sustained therapeutic effect while avoiding possible substrate inhibition issues as they transit through the gastrointestinal (GI) tract. Here, we propose addressing these issues using a probiotic yeast encapsulation strategy, Kluyveromyces lactis, based on gelatin hydrogels doubly cross-linked with graphene oxide (GO) and glutaraldehyde to form highly resistant nanocomposite encapsulates. GO was selected here as a reinforcement agent due to its unique properties, including superior solubility and dispersibility in water and other solvents, high biocompatibility, antimicrobial activity, and response to electrical fields in its reduced form. Finally, GO has been reported to enhance the mechanical properties of several materials, including natural and synthetic polymers and ceramics. The synthesized GO-gelatin nanocomposite hydrogels were characterized in morphological, swelling, mechanical, thermal, and rheological properties and their ability to maintain probiotic cell viability. The obtained nanocomposites exhibited larger pore sizes for successful cell entrapment and proliferation, tunable degradation rates, pH-dependent swelling ratio, and higher mechanical stability and integrity in simulated GI media and during bioreactor operation. These results encourage us to consider the application of the obtained nanocomposites to not only formulate high-performance nutraceuticals but to extend it to tissue engineering, bioadhesives, smart coatings, controlled release systems, and bioproduction of highly added value metabolites.

Tridimensional alginate disks of tunable topologies for mammalian cell encapsulation.

We have developed a protocol to produce three-dimensional matrices based on alginate hydrogels for mammalian cell encapsulation. Based on the gelation properties of this polysaccharide, we implemented a calcium ion-based diffusion method where the designed hydrogels can be obtained with well-defined mechanical properties and replicable 3D topologies. The developed protocol can be extended to different types of alginates and an ample range of concentrations. This makes it very attractive for various biomedical applications where strict control over structure-function relationships is desirable.

Enhanced biosorption of Cr(VI) using cotton fibers coated with chitosan - role of ester bonds.

We report on the role of ester bonds in the enhanced removal of hexavalent chromium from water using cotton fibers coated with chitosan. Adsorption capacities up to five times higher than those of the unmodified fibers were observed when the cotton fibers were exposed to an NaOH, followed by citric acid (0.97 M), and a chitosan solution (2%). We found that the use of NaOH favors the formation of ester bonds over amide bonds on the surface of the cotton fibers. This increase in the surface density of ester bonds generates an increase in the amount of exposed amino groups from the chitosan, hence increasing the removal capacity of the modified fibers. Experimental results also reveal that the adsorption is induced by the electrostatic attraction between the protonated amino groups on the surface and the negatively charged chromium ions in the water. Adsorption isotherms and kinetic studies indicated that the adsorption process fits the Langmuir and the Freundlich isotherm models as well as the pseudo-first and pseudo-second order kinetic models. These results can open a new avenue for the manufacturing of fibers with enhanced removal capacities for hexavalent chromium.

Gelatinization and retrogradation phenomena in starch/montmorillonite nanocomposites plasticized with different glycerol/water ratios.

This study aims to gain insights into the intermolecular interactions present in thermoplastic starch (TPS)/montmorillonite (MMT) nanocomposites prepared using water and/or glycerol as plasticizers. Specifically, the impact of using different glycerol/water proportions on the nature of gelatinization and retrogradation processes is studied. Nanocomposites were characterized by rheometry, scanning electron microscopy (SEM) and X-rays diffraction (XRD). It is shown that clay tactoids preferentially interact with glycerol molecules rather than starch macromolecules. Consequently, the effects of MMT incorporation strongly depend on the glycerol/water ratio; when a ratio of 0.5 is used minor variations were observed on the starch gelatinization process-although stronger clays-starch interactions were evident-whereas at higher ratios the addition of clays significantly increased the gelatinization temperature, up to values over 100°C. In the gelatinization process of starch in TPS samples having only glycerol as a plasticizer, the leaching of amylose and the melting of amylopectin crystalline domains seem to occur simultaneously. This different gelatinization mechanism produces a TPS having a substantially different morphology, which exhibited reduced retrogradation characteristics.