Artículos y presentaciones en Congresos
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Examinando Artículos y presentaciones en Congresos por Autor "Bolzan, Agustín Eduardo"
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Acceso Abierto Characterization of smart auto-degradative hydrogel matrix containing alginate lyase to enhance levofloxacin delivery against bacterial biofilms(2015) Islan, G.; Dini, C.; Bartel, L.; Bolzan, Agustín Eduardo; Castro, G.The aim of the present work is the characterization of smart auto-degradable microspheres composed of calcium alginate/high methoxylated pectin containing an alginate lyase (AL) fromSphingobacterium multivorumand levofloxacin. Microspheres were prepared by ionotropic gelation containing AL in its inactive form at pH 4.0. Incubation of microspheres in Tris–HCl and PBS buffers at pH 7.40 allowed to establish the effect of ion-chelating phosphate on matrix erodability and suggested an intrinsically activation of AL by turning the pH close to neutrality. Scanning electron and optical microscopies revealed the presence of holes and surface changes in AL containing microspheres. Furthermore, texturometric parameters, DSC profiles and swelling properties were showing strong changes in microspheres properties. Encapsulation of levofloxacin into microspheres containing AL showed 70% efficiency and 35% enhancement of antimicrobial activity againstPseudomonas aeruginosabiofilm. Levofloxacin release from microspheres was not changed at acidic pH, but was modified at neutral pH in presence of AL. Advantageously, only gel matrix debris were detectable after overnight incubation, indicating an autodegradative gel process activated by the pH. Absence of matrix cytotoxicity and a reduction of the levofloxacin toxicity after encapsulation were observed in mammalian CHO-K1 cell cultures. These properties make the system a potent and versatile tool for antibiotic oral delivery targeted to intestine, enhancing the drug bioavailability to eradicate bacterial biofilm and avoiding possible intestinal obstructions. - Artículo
Embargado First evidence of chromosomal variation within Chelonoidis chilensis (Testudines: Testudinidae)(2015) Sánchez, J.; Alcalde, L.; Bolzan, Agustín EduardoChelonoidis chilensis is an endangered tortoise that inhabits arid regions in Argentina, Bolivia and Paraguay. Blood samples were obtained from wild specimens from the Argentinan distribution range together with samples from specimens of known morphotype but unknown provenance. Cytogenetic analysis using Giemsa staining showed that the diploid chromosome complement was 2n=52 for all twenty-five tortoises analysed. Two different karyomorphs, termed A and B, were identified, with a karyotypic formulae of 7:5:14 and 6:5:15, respectively. G-band analysis suggests that karyomorph B may originate from a chromosomal fission event involving chromosome pair 7 of karyomorph A. In addition, all specimens analysed using Fluorescence In Situ Hybridisation (FISH) with a telomeric probe showed telomeric signals only at the terminal regions of chromosomes. This evidence suggests that the karyotype of C. chilensis does not have telocentric chromosomes, and that interstitial telomeric sequences have not played a major role during the recent chromosomal evolution of this species. Our data agree with recent molecular evidence supporting the existence of one instead several species for the C. chilensis complex. Our data further suggest a possible correlation between chromosomal variation and geographical distribution: karyomorph A is present in tortoises from the Dry Chaco Eco-region, whereas karyomorph B characterises tortoises living in the Monte of Steps and Plains Eco-region. Morphology appears to vary independently of cytomorph variation. - Artículo
Acceso Abierto The methylating agent streptozotocin induces persistent telomere dysfunction in mammalian cells(2015) Paviolo, N.; Santiñaque, F.; Castrogiovanni, Daniel; Folle, G.; Bolzan, Agustín EduardoWe analyzed chromosomal aberrations involving telomeres in the progeny of mammalian cells exposed to the methylating agent and antineoplastic/diabetogenic drug streptozotocin (STZ), to test whether it induces long-term telomere instability (by chromosome end loss and/or telomere dysfunction). Rat cells (ADIPO-P2 cell line, derived from Sprague-Dawley rat adipose cells) were treated with a single concentration of STZ (2mM). Chromosomal aberrations were analyzed 18h, 10 days, and 15 days after treatment, using PNA-FISH with a pan-telomeric probe [Cy3-(CCCTAA)3] to detect (TTAGGG)n repeats. Cytogenetic analysis revealed a higher frequency of chromosomal aberrations in STZ-exposed cultures vs. untreated cultures at each time point analyzed. The yield of induced aberrations was very similar at each time point. Induction of aberrations not involving telomere dysfunction was only observed 18h and 15 days after treatment, whereas induction of telomere dysfunction-related aberrations by STZ (mainly in the form of telomere FISH signal loss and duplications, most of them chromatid-type aberrations) was observed at each time point. Our results show that STZ induces persistent telomere instability in mammalian cells, cytogenetically manifested as telomere dysfunction-related chromosomal aberrations. Neither telomere length nor telomerase activity is related to the telomere dysfunction.