Fábio André Brayner dos Santos

Comparison of Smear Layer Removal Using the Nd:YAG Laser, Ultrasound, ProTaper Universal System, and CanalBrush Methods: An In Vitro Study

INTRODUCTION The aim of this study was to compare the efficacy of the Nd:YAG laser, ultrasound, the ProTaper Universal system (Dentsply Maillefer, Ballaigues, Switzerland), and the CanalBrush (Coltene Whaledent, Langenau, Germany) methods for the removal of the smear layer from the apical third of root canals. METHODS Fifty distal root canals from extracted human mandibular first molars were instrumented up to ProTaper Universal F5 and divided randomly into 5 groups (n = 10) according to the following final irrigation agitation techniques: no agitation (control), ProTaper Universal file, ultrasound, CanalBrush, and Nd:YAG laser. Specimens were observed under a scanning electron microscope. The presence of the smear layer was evaluated using a 3-grade scoring system. The data were analyzed with Cohen kappa, Kruskal-Wallis, and Mann-Whitney U tests. A level of significance of .05 was adopted. RESULTS The ultrasound group performed significantly better than the rest of the groups; 56.6% of the specimens revealed no smear layer, 44.4% showed the presence of a moderate smear layer, and no heavy smear layers were observed. In the Nd:YAG laser group, 30% of the specimens presented with no smear layer, 70% showed the presence of a moderate smear layer, and no heavy smear layers were observed. In contrast, a heavy smear layer was observed on the surfaces of the root canals in the CanalBrush (23.4%), ProTaper Universal (13.4%), and control (86.6%) groups. Statistically significant differences were observed (P < .05). CONCLUSIONS None of the agitation methods completely removed the smear layer. However, the ultrasound method performed significantly better followed by the Nd:YAG laser, the CanalBrush, and the ProTaper Universal system. Agitation of the irrigant improved smear layer removal in the apical third of the canal.

Ultrastructural aspects of melatonin cytotoxicity on Caco-2 cells in vitro

Colon adenocarcinoma is a disease expanding worldwide. Cancer of colon and rectum are among the top ten most insidious types in Brazil. In vitro and in vivo studies have demonstrated the efficacy of the hormone melatonin to prevent and reduce tumor growth. However, there are only few studies addressing the action of melatonin on Caco-2 cells. Thus, the cytotoxic effect of melatonin on the ultrastructure of Caco-2 cells was investigated. The MTT colorimetric method was used to assess the cytotoxicity. A total of 2×10(6)cells/mL were seeded in microplates and incubated at 50, 25, 12.5, 6.25, 3.125, 1.56, 0.78 and 0.0 (control) μg/mL of melatonin. For ultrastructural analysis concentrations with low, medium and high cytotoxicity plus the control were used for ultrastructural analysis. The concentrations 50, 1.56 and 0.78 μg/mL of melatonin showed low, medium and high cytotoxicity, respectively. Ultrastructurally, the control tumor cells were shown to be preserved. Caco-2 cells showed morphological changes at 50 μg/mL of melatonin, with numerous vacuoles, mitochondrial degeneration and reduced glycogen. However, Caco-2 cells also showed altered morphology in treatments at 1.56 and 0.78 μg/mL of melatonin with characteristics of cells in degeneration by the presence of numerous vacuoles, absence of microvilli, mitochondrial degeneration and nuclear fragmentation. Thus, one can infer that concentrations of 1.56 and 0.78 μg/mL of melatonin promote cytotoxicity in Caco-2 cells, which can probably be related to the generation of reactive oxygen species (ROS).

Ultrastructural Analysis of Leishmania infantum chagasi Promastigotes Forms Treated In Vitro with Usnic Acid

Leishmaniasis is considered by the World Health Organization as one of the infectious parasitic diseases endemic of great relevance and a global public health problem. Pentavalent antimonials used for treatment of this disease are limited and new phytochemicals emerge as an alternative to existing treatments, due to the low toxicity and cost reduction. Usnic acid is uniquely found in lichens and is especially abundant in genera such as Alectoria, Cladonia, Evernia, Lecanora, Ramalina, and Usnea. Usnic acid has been shown to exhibit antiviral, antiprotozoal, antiproliferative, anti-inflammatory, and analgesic activity. The aim of this study was to evaluate the antileishmanial activity of usnic acid on Leishmania infantum chagasi promastigotes and the occurrence of drug-induced ultrastructural damage in the parasite. Usnic acid was effective against the promastigote forms (IC50 = 18.30 ± 2.00 µg/mL). Structural and ultrastructural aspects of parasite were analyzed. Morphological alterations were observed as blebs in cell membrane and shapes given off, increasing the number of cytoplasmic vacuoles, and cellular and mitochondrial swelling, with loss of cell polarity. We concluded that the usnic acid presented antileishmanial activity against promastigote forms of Leishmania infantum chagasi and structural and ultrastructural analysis reinforces its cytotoxicity. Further, in vitro studies are warranted to further evaluate this potential.

Melatonin effect on the ultrastructure of Ehrlich ascites tumor cells, lifetime and histopathology in swiss mice

AIMS One of the models used for studying cancer is the Ehrlich ascites tumor (EAT) due to its ability to grow in liquid suspension, allowing a standard number of cells to be inoculated, growth quantification and regression of tumor mass. Among the oncostatic substances, melatonin has shown effectiveness in limiting the tumor cell proliferation. However, studies have shown contradictory effects of melatonin on the EAT. This study has investigated the melatonin effect on tumor growth, time and survival percentage, ultrastructure and metastasis of EAT cells in mice submitted or not to pinealectomy. MAIN METHODS Animals were inoculated with 5 x 106 cells/ml and treated or not with exogenous melatonin with doses of at 150 and 300μg/30g animal weight for 12days. Melatonin significantly reduced the abdominal circumference, volume of ascites liquid and EAT-cell viability, raising rates of time and mice survival percentage. KEY FINDINGS Ultrastructurally, the melatonin treatment revealed changes in the shape of cells, the cell surface showed numerous projections, some bifurcated, cytoplasmic vacuolation, mitochondrial degeneration and nuclear fragmentation, peculiar characteristics of apoptosis. Histopathology revealed no metastasis in the liver, small intestine and large intestine in any of the animals in the experimental groups; however this process was evident in the lungs and kidneys, being inhibited by melatonin administration. SIGNIFICANCE Thus, we can conclude that doses of 150 and 300μg/30g of melatonin for 12 consecutive days have a very effective oncostatic and cytotoxic activity on EAT cells in mice.

Ultrastructural aspects of cranial and peripheric nerves of cronically diabetic and malnourished rats: a short biochemical panorama

Diabetes Mellitus is one of the most common causes of neuropathies, which can be caused by molecular imbalances that impair metabolic pathways. Studies in rats showed the importance of sirtuins (SIRT), deacetylases that use NAD+ as a cofactor, which have a widespread function in metabolism, and their relation when food deprived or calorie restricted. Additionally, diabetic neuropathy presents different structural biomarkers that cause morphological alterations in fibers that can be partially treated. SIRT1 is the principal sirtuin, which acts on hypothalamus, liver, kidney, among other organs, up regulating or down regulating the expression of some genes or enzymes crucial in the process of glucose absorption.

Experimental periodontitis in rats potentiates inflammation at a distant site: Role of B1 kinin receptor

&NA; It has been demonstrated that periodontitis, a chronic oral disease, can induce systemic inflammation which is associated with systemic diseases, including rheumatoid arthritis. Here, we evaluated whether periodontitis can modulate the inflammatory response at a site distant to the oral cavity. Wistar rats were subjected to ligature‐induced experimental periodontitis. Fourteen days after the procedure, paw edema was induced by carrageenan or by different receptor‐specific inflammatory mediators. Blood and the tissue of the paws were obtained for TNF‐&agr; and IL‐1&bgr; measurement. It was observed that carrageenan‐induced paw edema and leukocyte migration was potentiated in periodontitis animals. The edema induced by carrageenan, bradykinin and des‐Arg9‐BK (B1 agonist) was also potentiated in periodontitis animals and blocked by a B1 antagonist. Ligature‐induced periodontitis increased plasma levels of TNF‐&agr; and tissue IL‐1&bgr;. Periodontitis also up‐regulated kinin B1 receptor expression in paw tissue. Additionally, the treatment of ligature animals with anti‐TNF‐&agr;, etanercept, completely abolished the potentiation of edema induced by des‐Arg9‐BK. Taken together, these results show that experimental periodontitis in rats can induce systemic inflammation through the up‐regulation of kinin B1 receptors at a site distant from the oral cavity, modifying the inflammatory response. Graphical abstract: The experimental periodontitis in rats can induce systemic inflammation and up‐regulate B1 receptors in the rat paw, modifying the inflammatory response at a site distant from oral infection. Figure. No caption available.

Factors Associated With Diabetic Neuropathy In Rats: A Systematic Review With Metanalysis

Diabetic neuropathy refers to a group of symptoms associated with the nerve’s damaged ability to perform its functions correctly. Symptoms may vary from paresis to pains that mainly affect sensitive or motor long nerves of feet and hands. Hence, experiments and analysis carried out with rodents, especially rats, allow several clinical interfaces to be known. Therefore, the aim of this study was to analyze the factors associated with diabetic neuropathy in rats. This is a systematic review with metanalysis. Data collection followed some priorelection criteria. The sources of information for the researched data are the databases MEDLINE/PubMed and Scopus. The research was conducted using the keywords found in descriptors/MeSH: rats, diabetic neuropathies, and risk factors with the Boolean operator “AND”. The BioEstat 5.3 was used for statistical analysis, and the Odds Ratio was calculated with a 95% confidence interval (CI). Eighty-three references were found, of which 17 followed the criteria and were then included in the present review. Some factors like nerve morphology, blood hypertension, oxidative stress, diabetes period, hypoglycemic effect, vascular complications, and insulin parameters represent the main risk factors for the development of diabetic neuropathy, as well as diabetes induction in rats by using drugs. Such factors are verysimilar to those from humans, thus requiring a deeper analysis of the theme in a considerable human sample.