Protection of normal cells from irradiation bystander effects by silica-flufenamic acid nanoparticles.

The development of a myriad of nanoparticles types has opened new possibilities for the diagnostics and treatment of many diseases, especially for cancer. However, most of the researches done so far do not focus on the protection of normal cells surrounding a tumor from irradiation bystander effects that might lead to cancer recurrence. Gap-junctions are known to be involved in this process, which leads to genomic instability of neighboring normal cells, and flufenamic acid (FFA) is included in a new group of gap-junction blockers recently discovered. The present work explores the use of mesoporous silica nanoparticles MCM-41 functionalized with 3-Aminopropyltriethoxysilane (APTES) for anchoring the flufenamic acid for its prolonged and controlled release and protection from radiation bystander effects. MCM-41 and functionalized samples were structurally and chemically characterized with multiple techniques. The biocompatibility of all samples was tested in a live/dead assay performed in cultured MRC-5 and HeLa cells. HeLa cells cultured were exposed to 50 Gy of gamma-rays and the media transferred to fibroblast cells cultured separately. Our results show that MCM-41 and functionalized samples have high biocompatibility with MCR-5 and HeLa cells, and most importantly, the FFA delivered by these NPs was able to halt apoptosis, one of main bystander effects.

Response of Fibroblasts MRC-5 to Flufenamic Acid-Grafted MCM-41 Nanoparticles.

Recently, flufenamic acid (FFA) was discovered among fenamates as a free radical scavenger and gap junction blocker; however, its effects have only been studied in cancer cells. Normal cells in the surroundings of a tumor also respond to radiation, although they are not hit by it directly. This phenomenon is known as the bystander effect, where response molecules pass from tumor cells to normal ones, through communication channels called gap junctions. The use of the enhanced permeability and retention effect, through which drug-loaded nanoparticles smaller than 200 nm may accumulate around a tumor, can prevent the local side effect upon controlled release of the drug. The present work, aimed at functionalizing MCM-41 (Mobil Composition of Matter No. 41) silica nanoparticles with FFA and determining its biocompatibility with human fibroblasts MRC-5 (Medical Research Council cell strain 5). MCM-41, was synthesized and characterized structurally and chemically, with multiple techniques. The biocompatibility assay was performed by Live/Dead technique, with calcein and propidium-iodide. MRC-5 cells were treated with FFA-grafted MCM-41 for 48 h, and 98% of cells remained viable, without signs of necrosis or morphological changes. The results show the feasibility of MCM-41 functionalization with FFA, and its potential protection of normal cells, in comparison to the role of FFA in cancerous ones.

Eficiencia de tres técnicas en la remoción de gutapercha / Efficiency of three different techniques in the removal of gutta-percha

Cuando la terapia endodóntica fracasa, las opciones para solucionar este problema incluyen preservar el diente a través del retratamiento ortógrado o cirugía apical. Siempre que sea posible, el retratamiento endodóntico no quirúrgico debe ser la opción elegida. Diferentes sistemas rotatorios han sido propuestos como una alternativa a la instrumentación manual para la remoción de la gutapercha.El objetivo de este trabajo fue comparar la eficacia y la eficiencia en la desobturación total del canal radicular, utilizando dos tipos de instrumentos rotatorios: limas Protaper Universal® y limas Protaper Retratamiento® con limas manuales tipo K. Se instrumentaron 45 canales radiculares, con limas mecanizadas del sistema Mtwo®, hasta la 25/06 y terminados de conformar con lima K #40 e irrigados con hipoclorito de sodio al 2,5 % entre cada instrumento. Los dientes fueron obturados con técnica de condensación lateral, utilizando conos de gutapercha y cemento Tubliseal®.La muestra se dividió al azar en tres grupos A, B y C, de 15 canales cada uno, el grupo A se desobturó con limas Protaper Universal. El grupo B se desobturó con limas Protaper retratamiento y el grupo C se desobturó totalmente con limas K. Se cronometró cada procedimiento de desobturación y al término de esta, se tomó una radiografía en sentido buco-lingual y otra en sentido mesio-distal para cuantificar la remoción de gutapercha en cada grupo. Los resultados muestran que no existe diferencia significativa en la eliminación total del relleno endodóntico entre los tres grupos (p= 0,271) pero que los tiempos empleados en la desobturación total de los canales entre los grupos, muestra diferencias significativas entre Protaper Retratamiento y limas K, y entre Protaper Universal y limas K (p <0,05). Bajo las condiciones de este estudio, ningún sistema fue capaz de remover toda la gutapercha del interior del canal radicular.

When primary endodontic treatment fails, the treatment alternatives for root preservation are orthograde retreatment or apical surgery. Whenever possible, orthograde retreatment must be the first option. Different rotary systems have been proposed as an alternative to manual instrumentation for the removal of gutta-percha. The aim of this study was to compare the efficacy and efficiency of the total removal of gutta-percha from root canals, using two types of rotary instruments: Protaper Universal Files® and Protaper Retreatment Files®, compared to manual K type Files. A total of forty-five canals were instrumented with Mtwo files® up to a 25.06 file and the shaping was completed with a 40 K-type File and irrigated with 2.5 % Sodium Hypochlorite between each instrument. The teeth were obturated with Lateral Condensation Technique, using gutta-percha and Tubliseal® sealer. Samples were divided in groups A, B and C, 15 canals each, and gutta-percha was removed using the following protocols: group A with Protaper Universal; Group B using Protaper Retreatment and Group C using K type Files. Each procedure was timed and at the end of it, two periapical radiographs were taken: one buccolingual and one mesiodistal, in order to quantify the amount of gutta-percha removed. The results analysis show that there is no significant difference in the amount of gutta-percha removed between the three groups (p= 0.271) but that the time invested to perform the removal of the gutta-percha was significantly less between for the rotary systems, when compared to manual instrumentation (p <0.05). Under the conditions of this study, no system was able to remove all gutta percha inside the root canal.

Shear stress influences the pluripotency of murine embryonic stem cells in stirred suspension bioreactors.

Pluripotent embryonic stem cells (ESCs) have been used increasingly in research as primary material for various tissue-engineering applications. Pluripotency, or the ability to give rise to all cells of the body, is an important characteristic of ESCs. Traditional methods use leukaemia inhibitory factor (LIF) to maintain murine embryonic stem cell (mESC) pluripotency in static and bioreactor cultures. When LIF is removed from mESCs in static cultures, pluripotency genes are downregulated and the cultures will spontaneously differentiate. Recently we have shown the maintenance of pluripotency gene expression of mESCs in stirred suspension bioreactors during differentiation experiments in the absence of LIF. This is undesired in a differentiation experiment, where the goal is downregulation of pluripotency gene expression and upregulation of gene expression characteristic to the differentiation. Thus, the objective of this study was to examine how effectively different levels of shear stress [100 rpm (6 dyne/cm(2) ), 60 rpm (3 dyne/cm(2) )] maintained and influenced pluripotency in suspension bioreactors. The pluripotency markers Oct-4, Nanog, Sox-2 and Rex-1 were assessed using gene expression profiles and flow-cytometry analysis and showed that shear stress does maintain and influence the gene expression of certain pluripotency markers. Some significant differences between the two levels of shear stress were seen and the combination of shear stress and LIF was observed to synergistically increase the expression of certain pluripotency markers. Overall, this study provides a better understanding of the environmental conditions within suspension bioreactors and how these conditions affect the pluripotency of mESCs.

The ATP-sensitive potassium channel blocker glibenclamide prevents renal ischemia/reperfusion injury in rats.

BACKGROUND: Renal ischemia/reperfusion (I/R) is a complex neutrophil-mediated syndrome. Adenosine-triphosphate (ATP)-sensitive potassium (K(ATP)) channels are involved in neutrophil migration in vivo. In the present study, we have investigated the effects of glibenclamide, a K(ATP) channel blocker, in renal I/R injury in rats. METHODS: The left kidney of the rats was excised through a flank incision and ischemia was performed in the contralateral kidney by total interruption of renal artery flow for 45 minutes. Renal perfusion was reestablished, and the kidney and lungs were removed for analysis of vascular permeability, neutrophil accumulation, and content of cytokines [tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta, and IL-10] 4 and 24 hours later. Renal function was assessed by measuring creatinine, Na(+), and K(+) levels in the plasma and by determination of creatinine clearance. Drugs were administered subcutaneously after the onset of ischemia. RESULTS: Reperfusion of the ischemic kidney induced local (kidney) and remote (lung) inflammatory injury and marked renal dysfunction. Glibenclamide (20 mg/kg) significantly inhibited the reperfusion-associated increase in vascular permeability, neutrophil accumulation, increase in TNF-alpha levels and nuclear factor-kappaB (NF-kappaB) translocation. These inhibitory effects were noticed in the kidney and lungs. Moreover, glibenclamide markedly ameliorated the renal dysfunction at 4 and 24 hours. CONCLUSION: Treatment with glibenclamide is associated with inhibition of neutrophil recruitment and amelioration of renal dysfunction following renal I/R. Glibenclamide may have a therapeutic role in the treatment of renal I/R injury, such as after renal transplantation.