Efectos citotóxicos de gluconato de clorhexidina en células epiteliales

La necesidad de nuevos agentes antimicrobianos seguros y eficaces, constituyen una prioridad a nivel mundial como alternativas tanto en la prevención, así como en el tratamiento de enfermedades infecciosas debido al incremento de patógenos multirresistentes. La clorhexidina (CHX) ha sido ampliamente utilizada como agente antiséptico en medicina y odontología, con una excelente efectividad  El presente trabajo tuvo como objetivo evaluar la citotoxicidad de la CHX sobre cultivo de la línea celular HeLa. El efecto citotóxico de la CHX fue determinada mediante el ensayo de viabilidad celular MTT. El daño al ADN genómico de la células fue evaluado por el ensayo del cometa, y finalmente para detectar apoptosis se determinó mediante el ensayo de Anexina V. Nuestros resultados mostraron un 0.72% de células viables, representando una toxicidad severa a 1 minuto de exposición por CHX. El ensayo del cometa fue positivo a CHX, dañando el ADN de células HeLa y mostrando la estela clásica de un cometa al mismo tiempo que el control positivo de daño al ADN (Etopósido, ETO). Finalmente, se detectó que la CHX puede llevar a la destrucción de la célula. En conclusión, la clorhexidina es un excelente antiséptico sin embargo, con la incapacidad de excluir a las células de mamífero lo que puede llegar a la destrucción de las mismas teniendo consecuencias importantes en la curació

Efectividad antibiofilm de un gel con nano partículas de bismuto sobre Enterococcus faecalis intraconducto.

El objetivo de este trabajo fue evaluar la actividad antibiofilm de un gel con nanopartículas de bismuto (Gel-BisBAL NPs) sobre Enterococcus faecalis intraconducto

Citotoxicidad y genotoxicidad del clorhidrato de octenidina sobre células humanas

El clorhidrato de  octenidina se emplea como ingrediente principal de enjuagues bucales debido a sus  propiedades bactericidas y antibiopelícula. Aunque la octenidina es ampliamente utilizada, no hay reportes previos que indiquen su posible efecto tóxico en los seres humanos. El objetivo de esta investigación fue analizar la citotoxicidad de la octenidina en las células epiteliales humanas (HeLa). Células HeLa fueron cultivadas y expuestas a varias concentraciones de octenidina y la viabilidad celular se midió mediante ensayos de MTT. Los resultados obtenidos mostraron que no había células vivas después de 24 hrs de incubación al ser tratadas con 0,0125 a 0,05% de octenidina. Sorprendentemente,  las mismas concentraciones de octenidina tuvieron un efecto citotóxico en todas las células HeLa después de sólo 5 minutos de exposición. Estos datos fueron apoyados por la observación de las mismas cultivadas con octenidina mediante microscopía de fluorescencia, que indicaron el daño sobre la membrana plasmática, probablemente alterando su permeabilidad. Empleando ensayos de genotoxicidad, se encontró que la octenidina causa lesiones al ADN genómico. Las concentraciones más bajas de octenidina indujeron un aumento de los niveles de IL-6. Sin embargo, no promueve la apoptosis entre las células epiteliales. Como conclusión; la octenidina es altamente tóxico en las células humanas, por lo tanto los efectos benéficos y nocivos de la octenidina en los seres humanos deben ser valorados en estudios in vivo

REVISÃO ESTRATIGRÁFICA DA BACIA DE RESENDE, RIFT CONTINENTAL DO SUDESTE DO BRASIL, ESTADO DO RIO DE JANEIRO

This paper presents a stratigraphic revision of the Tertiary alluvial deposits of the Resende Sedimentary Basin (State of Rio de Janeiro, Southeastern Brazil Continental Rift). Six sedimentary facies associations were recognized and gathered into three stratigraphic units named, from the lower to the upper, Ribeirão dos Quatis Formation, Resende Formation (with its Itatiaia and Acácias members), and Floriano Formation. The Ribeirão dos Quatis Formation is composed by conglomeratic and sandy deposits that represent a sedimentary record previous to the main tectonic episode that originates the basin. Following this unit, the tectonic evolution generated an ENE-WSW half-graben, with alluvial fans along its northern main fault, feeding an axial fluvial system. These alluvial successions correspond to the Resende Formation, representing the main deposits of the basin. The alluvial successions, rich in alkaline rock debris proceeding from the Itatiaia and Morro Redondo massives, were individualized as Itatiaia Member. A newer axial braided fluvial system, characterized by superposition of conglomeratic and arenaceous beds in fining upward cycles, and thick layers of massive pelites, was individualized as Acácias Member. Meandering river deposits related to Floriano Formation represent the Tertiary final filling of the basin.Propõe-se aqui uma revisão estratigráfica dos depósitos aluviais terciários da Bacia de Resende, inserida no Rift Continental do Sudeste do Brasil, no extremo oeste do Estado do Rio de Janeiro. Foram distinguidas seis associações de fácies, subdivididas em três unidades litoestratigráficas, denominadas, da base para o topo: Formação Ribeirão dos Quatis, Formação Resende (com seus membros Itatiaia e Acácias) e Formação Floriano. Os depósitos conglomeráticos e arenosos da Formação Ribeirão dos Quatis representam um registro sedimentar anterior ao principal episódio tectônico extensional gerador da bacia. Com a evolução deste processo, formou-se um hemigráben de direção ENE-WSW e ao longo da falha principal acumularam-se leques aluviais alimentadores de um sistema fluvial entrelaçado axial, resultando nos depósitos mais típicos da consagrada Formação Resende. As sucessões aluviais ricas em detritos de rochas alcalinas, provenientes da erosão dos maciços alcalinos adjacentes, foram individualizadas no Membro Itatiaia. Em um momento posterior da evolução da bacia, implantou-se um novo sistema fluvial entrelaçado axial, caracterizado pela superposição de estratos arenosos e conglomeráticos em ciclos de granodecrescência ascendente, e por espessas camadas de pelitos maciços, sendo individualizado como Membro Acácias. Os sedimentos da Formação Floriano representam depósitos de rios meandrantes, relacionados ao preenchimento final da bacia no Terciário

Bismuth oxide aqueous colloidal nanoparticles inhibit Candida albicans growth and biofilm formation

Abstract: Multiresistance among microorganisms to common antimicrobials has become one of the most significant concerns in modern medicine. Nanomaterials are a new alternative to successfully treat the multiresistant microorganisms. Nanostructured materials are used in many fields, including biological sciences and medicine. Recently, it was demonstrated that the bactericidal activity of zero-valent bismuth colloidal nanoparticles inhibited the growth of Streptococcus mutans; however the antimycotic potential of bismuth nanostructured derivatives has not yet been studied. The main objective of this investigation was to analyze the fungicidal activity of bismuth oxide nanoparticles against Candida albicans, and their antibiofilm capabilities. Our results showed that aqueous colloidal bismuth oxide nanoparticles displayed antimicrobial activity against C. albicans growth (reducing colony size by 85%) and a complete inhibition of biofilm formation. These results are better than those obtained with chlorhexidine, nystatin, and terbinafine, the most effective oral antiseptic and commercial antifungal agents. In this work, we also compared the antimycotic activities of bulk bismuth oxide and bismuth nitrate, the precursor metallic salt. These results suggest that bismuth oxide colloidal nanoparticles could be a very interesting candidate as a fungicidal agent to be incorporated into an oral antiseptic. Additionally, we determined the minimum inhibitory concentration for the synthesized aqueous colloidal Bi2 O3 nanoparticles

Zerovalent bismuth nanoparticles inhibit Streptococcus mutans growth and formation of biofilm

Background and methods: Despite continuous efforts, the increasing prevalence of resistance among pathogenic bacteria to common antibiotics has become one of the most significant concerns in modern medicine. Nanostructured materials are used in many fields, including biological sciences and medicine. While some bismuth derivatives has been used in medicine to treat vomiting, nausea, diarrhea, and stomach pain, the biocidal activity of zerovalent bismuth nanoparticles has not yet been studied. The objective of this investigation was to analyze the antimicrobial activity of bismuth nanoparticles against oral bacteria and their antibiofilm capabilities. Results: Our results showed that stable colloidal bismuth nanoparticles had 69% antimicrobial activity against Streptococcus mutans growth and achieved complete inhibition of biofilm formation. These results are similar to those obtained with chlorhexidine, the most commonly used oral antiseptic agent. The minimal inhibitory concentration of bismuth nanoparticles that interfered with S. mutans growth was 0.5 mM. Conclusion: These results suggest that zerovalent bismuth nanoparticles could be an interesting antimicrobial agent to be incorporated into an oral antiseptic preparation

Eficacia antimicrobiana y antibiofilm de un hidrogel cargado con nanopartículas lipofílicas de bismuto sobre bacterias periodonto patógenas.

La enfermedad periodontal es un desorden crónico inflamatorio causado por la colonización de microorganismos en la bolsa periodontal y creciendo dentro de biopelículas. A pesar de ser una infección localizada, existen muy pocas opciones de tratamiento tópicas de tipo no antibiótico para combatir a estos microorganismos

Effect of Lipophilic Bismuth Nanoparticles on Erythrocytes

Lipophilic bismuth dimercaptopropanol nanoparticles (BisBAL NPs) have a very important antimicrobial activity; however their effect on human cells or tissues has not been completely studied. Undesirable effects of bismuth include anemia which could result from suicidal erythrocyte death or eryptosis. The objective of this research was to determine the effect of bismuth dimercaptopropanol nanoparticles on blood cells. The nanoparticles are composed of 53 nm crystallites on average and have a spherical structure, agglomerating into clusters of small nanoparticles. Based on cell viability assays and optical microscopy, cytotoxicity on erythrocytes was observed after growing with 500 and 1000 µM of BisBAL NPs for 24 h. AM Calcein was retained inside erythrocytes when they were exposed to 100 µM (or lower concentrations) of BisBAL NPs for 24 h, suggesting the absence of damage in plasmatic membrane. Genotoxic assays revealed no damage to genomic DNA of blood cells after 24 h of exposition to BisBAL NPs. Finally, 100–1000 µM of bismuth nanoparticles promotes apoptosis between blood cells after 24 h of incubation. Hence BisBAL NPs at concentrations lower than 100 µM do not cause damage on blood cells; they could potentially be used by humans without affecting erythrocytes and leukocytes