Fluoride effect on the process of alveolar bone repair in rats: evaluation of activity of MMP-2 and 9

Objective: The aim of this study was to evaluate comparatively the effect of fluoride (F) on the activity of matrix metalloproteinases 2 and 9 (MMP-2 and MMP-9) involved in process of alveolar bone repair. Material and methods: This study used 4 groups of Wistar rats with 80 days of life (n = 160) which received drinking water containing different doses of fluoride (NaF): 5, 15, 50 ppm and deionized water (control) throughout the experiment. These animals had their right upper incisors extracted. After extraction, the animals were euthanized at 7, 14, 21 and 30 days and the hemi-maxillae were collected for microscopic analysis (Hematoxylin and Eosin and immunohistochemistry for MMP-9) and zymography (MMP-2 and 9).Results: Microscopically the process of bone repair was similar in all groups, being noted only a delay of the blood clot resorption and bone formation in the group of 50 ppm F. The expression for MMP-9 showed differences betweengroups only during the initial repair (7 days). However, the zymography showed no significant differences between treated and control groups. Conclusion: Ours results suggest an effect of fluoride on the activity of MMPs 2 and 9 at the initial period of alveolar repair which could be associated to the process of blood clot remission and delay in bone repair. Further studies are needed to establish the relationship between the initial process of resorption of the blood clot, and the involvement of MMPs 2 and 9 and its regulators/tissue inhibitors.

Efeito da ingestão crônica do fluoreto sobre o sistema oxidante/antioxidante de ratos / Effect of chronic fluoride intake in the oxidant/antioxidant system of rats

A ingestão excessiva de fluoreto por um longo período de tempo pode resultar em fluorose, que pode causar manifestações dentárias e esqueléticas. Danos metabólicos, funcionais e estruturais causados pela fluorose crônica tem sido relatados em vários tecidos. O objetivo deste estudo foi avaliar os efeitos do fluoreto administrado na água de beber, da administração de fluoreto na água de beber na defesa antioxidante de ratos. Quatro grupos de ratos wistar foram usados (n=10/grupo). Os animais receberam água de beber contendo 0 (controle), 5, 15 ou 50 ppm de fluoreto durante 60 dias. Eles foram eutanasiados e os tecidos (fígado, rins e coração) e plasma foram coletados e homogenizados. Superóxido dismutase (SOD), catalase (CAT), glutationa peroxidase (GPx), glutationa reduzida (GSH), substâncias antioxidantes totais (SAT), substâncias reativas ao ácido tiobarbitúrico (TBARS), hidroperóxido de lipídios (HL) e fluoreto foram análisadas. Dados foram analisados por ANOVA e teste de Tukey ou Kruskal-Wallis e teste de Dunn (p<0,05). Nos rins, SOD, GPx, GSH e SAT diminuiram e fluoreto e HL aumentaram significantivamente. No fígado, CAT e TBARS diminuiram, SOD, HL e SAT aumentaram significativamente. No coração, GPx aumentou significativamente. No plasma, SOD e HL diminuiram significativamente. Em resumo, esses resultados mostram que a administração crônica de fluoreto altera o sistema antioxidante de ratos. Nosso dados sugerem que a exposição em níveis elevados de fluoreto, a conversão do ânion superóxido em água nos rins parecem ocorrer principalmente através da SOD e CAT, com baixa participação do sistema glutationa, diferindo do que parece ocorrer no fígado.

Excessive fluoride intake over a long period of time could result in fluorosis, which can lead to dental and skeletal manifestations. Metabolic, functional and structural damages caused by chronic fluorosis have been reported in many tissues. The aim of this study was to evaluate the effect of fluoride, administered in drinking water, in the antioxidant defense of rats. Four groups of Wistar rats were included (n=10/group). The animals received drinking water containing 0 (control), 5, 15 or 50 ppm of fluoride during 60 days. They were euthanized and the tissues (liver, kidney and heart) and plasma were collected and homogenized. Superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), reduced glutathione (GSH), antioxidants, thiobarbituric acid reactive substances (TBARS), lipid hydroperoxide (LH), and fluoride were analyzed. Data were analyzed by ANOVA and Tukeys test or Kruskal-Wallis and Dunns tests (p<0.05). In the kidney SOD, GPx, GSH and SAT decreased and fluoride and LH increased significantly. In the liver, CAT and TBARS decreased and fluoride, SOD, LH and SAT increased significantly. In the heart, GPx increased significantly. In the plasma, SOD and LH decreased significantly. In summary, these results show that chronic fluoride administration alters the antioxidant system of the rats. Our data suggest that upon exposure to high levels of fluoride, the conversion of the superoxide anion to water in the kidney seems to occur mainly through the SOD and CAT, with a low participation of the glutathione system, differing from what seems to occur in the liver.

Efeito da ingestão crônica do fluoreto sobre o sistema oxidante/antioxidante de ratos / Effect of chronic fluoride intake in the oxidant/antioxidant system of rats

A ingestão excessiva de fluoreto por um longo período de tempo pode resultar em fluorose, que pode causar manifestações dentárias e esqueléticas. Danos metabólicos, funcionais e estruturais causados pela fluorose crônica tem sido relatados em vários tecidos. O objetivo deste estudo foi avaliar os efeitos do fluoreto administrado na água de beber, da administração de fluoreto na água de beber na defesa antioxidante de ratos. Quatro grupos de ratos wistar foram usados (n=10/grupo). Os animais receberam água de beber contendo 0 (controle), 5, 15 ou 50 ppm de fluoreto durante 60 dias. Eles foram eutanasiados e os tecidos (fígado, rins e coração) e plasma foram coletados e homogenizados. Superóxido dismutase (SOD), catalase (CAT), glutationa peroxidase (GPx), glutationa reduzida (GSH), substâncias antioxidantes totais (SAT), substâncias reativas ao ácido tiobarbitúrico (TBARS), hidroperóxido de lipídios (HL) e fluoreto foram análisadas. Dados foram analisados por ANOVA e teste de Tukey ou Kruskal-Wallis e teste de Dunn (p<0,05). Nos rins, SOD, GPx, GSH e SAT diminuiram e fluoreto e HL aumentaram significantivamente. No fígado, CAT e TBARS diminuiram, SOD, HL e SAT aumentaram significativamente. No coração, GPx aumentou significativamente. No plasma, SOD e HL diminuiram significativamente. Em resumo, esses resultados mostram que a administração crônica de fluoreto altera o sistema antioxidante de ratos. Nosso dados sugerem que a exposição em níveis elevados de fluoreto, a conversão do ânion superóxido em água nos rins parecem ocorrer principalmente através da SOD e CAT, com baixa participação do sistema glutationa, diferindo do que parece ocorrer no fígado.

Excessive fluoride intake over a long period of time could result in fluorosis, which can lead to dental and skeletal manifestations. Metabolic, functional and structural damages caused by chronic fluorosis have been reported in many tissues. The aim of this study was to evaluate the effect of fluoride, administered in drinking water, in the antioxidant defense of rats. Four groups of Wistar rats were included (n=10/group). The animals received drinking water containing 0 (control), 5, 15 or 50 ppm of fluoride during 60 days. They were euthanized and the tissues (liver, kidney and heart) and plasma were collected and homogenized. Superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), reduced glutathione (GSH), antioxidants, thiobarbituric acid reactive substances (TBARS), lipid hydroperoxide (LH), and fluoride were analyzed. Data were analyzed by ANOVA and Tukeys test or Kruskal-Wallis and Dunns tests (p<0.05). In the kidney SOD, GPx, GSH and SAT decreased and fluoride and LH increased significantly. In the liver, CAT and TBARS decreased and fluoride, SOD, LH and SAT increased significantly. In the heart, GPx increased significantly. In the plasma, SOD and LH decreased significantly. In summary, these results show that chronic fluoride administration alters the antioxidant system of the rats. Our data suggest that upon exposure to high levels of fluoride, the conversion of the superoxide anion to water in the kidney seems to occur mainly through the SOD and CAT, with a low participation of the glutathione system, differing from what seems to occur in the liver.

Alkaline phosphatase activity in plasma and liver of rats submitted to chronic exposure to fluoride

The aim of this study was to compare the effect of fluoride (F) on alkaline phosphatase activity in the liver and plasma of the rats. Four groups of male Wistar rats (n=6), which received drinking water containing 5, 15 or 50 ppm F or deionized water (control) throughout the experiment were included in the study. The animals were euthanized and had their tissues and blood plasma collected for the analysis of fluoride and alkaline phosphatase. There was an increase in F concentration in most tissues in the animals treated with higher F concentrations, except for the heart. The alkaline phosphatase assay showed an increase in the activity in the liver and blood plasma of the animals treated with fluoride concentrations of 15 and 50 ppm (p<0.05). This study suggested that F at a concentration of 50 ppm in drinking water promotes increased the activity of alkaline phosphatase in the liver and blood plasma.

Análise morfométrica da resposta tecidual ao osso bovino misto medular implantado em defeito ósseo na calvária de rato / Morphometric analysis of tissue response to mixed bovine bone marrow implanted in bone defects in rat calvaria

O propósito deste trabalho foi avaliar o reparo ósseo de defeito de tamanho crítico em crânio de ratos tratados com disco de osso bovino misto (OBM) medular poroso. Foram utilizados 30 ratos Wistar machos adultos submetidos à cirurgia para confecção de um defeito circular de 8 mm de diâmetro removendo toda a díploe da calvaria. Os defeitos foram preenchidos com um disco de OBM de 8 mm de diâmetro por 3 mm de espessura, enquanto no grupo controle o defeito ósseo foi preenchido com coágulo sanguíneo do próprio animal. Os animais foram mortos após 30, 60 e 120 dias. As peças foram removidas, fixadas em formol 10% tamponado, desmineralizadas e processadas pela técnica histotécnica padrão para coloração em hematoxilina e eosina. Os cortes foram submetidos à análise histológica descritiva e morfometria (densidade de volume). Os resultados demonstraram uma pequena diminuição do material implantado com o decorrer dos períodos experimentais, sugerindo uma reabsorção lenta e gradual do OBM. Em contrapartida foi observado uma pequena neoformação óssea nos dois grupos (teste e controle) e formação de tecido conjuntivo denso nas áreas do defeito ósseo aos 120 dias também nos dois grupos. O tecido conjuntivo, no grupo teste, foi capaz de penetrar nos poros do material e ocupar esses espaços com o passar dos períodos. Dentro dos limites desse estudo, pode-se afirmar que o OBM é biocompativel, no entanto, não apresenta capacidade osteocondutora ou osteoindutora em defeitos críticos na calvária de ratos Wistar.

The purpose of this study was to evaluate bone repair of critical size defects in the calvarias of rats treated with bovine bone mixed disk (OBM) porous medullary. We used 30 adult male Wistar rats that underwent surgery to confection a bone defect of 8 mm diameter circular removing diploe calvaria completely. The defects were filled with a disc of OBM 8 mm diameter and 3 mm thick, while the control group the bone defect was filled with blood clot. The animals were killed after 30, 60 and 120 days. The pieces were removed, fixed in 10% buffered formalin, demineralized and processed by standard technique to staining with hematoxylin and eosin. The sections were submitted to descriptive histology and morphometry (volume density). The results showed a small decrease of the implanted material in the course of the experimental periods, suggesting a slow and gradual resorption of the OBM. On the other hand, there was a small new bone formation observed in both groups (test and control) and formation of dense connective tissue areas of the bone defect at 120 days also in the two groups. The connective tissue in the test group was able to penetrate the pores of the material and occupy these spaces over the periods. Within the limits of this study, it can be said that the OBM is biocompatible, however, does not have osteoinductive or osteoconductive capacity in critical defects in the calvaria of rats.

Manipulação do genoma humano: ética e direito / Manipulation of the human genome: ethics and law

A biologia molecular tem fornecido as ferramentas básicas para os geneticistas se aprofundarem nos mecanismos moleculares que influem na variação das doenças. Deve-se destacar a responsabilidade científica e moral dos pesquisadores, uma vez que os cientistas devem imaginar as consequências morais da aplicação comercial de testes genéticos, já que esse fato envolve não só o indivíduo e suas famílias, mas toda a população. Além de ser preciso, também, fazer uma reflexão sobre como essas informações do genoma humano serão utilizadas, para o bem ou mal. O objetivo desta revisão foi trazer à luz do conhecimento dados sobre características éticas da aplicação da biologia molecular, relacionando-a com os direitos do ser humano. Após análise bibliográfica, pôde-se observar que o Projeto Genoma Humano gerou várias possibilidades, como identificação de genes associados a doenças com propriedades sinergísticas, mas modificando às vezes comportamentos ao intervir geneticamente no ser humano, trazendo benefícios ou malefícios sociais. O grande desafio é decidir o que a humanidade pretende em relação a este gigantesco salto.

The molecular biology has provided the basic tool for geneticists deepening in the molecular mechanisms that influence different diseases. It should be noted the scientific and moral responsibility of the researchers, because the scientists should imagine the moral consequences of the commercial application of genetic tests, since this fact involves not only the individual and their families, but the entire population. Besides being also necessary to make a reflection on how this information from the human genome will be used, for good or bad. The objective of this review was to bring the light of knowledge, data on characteristics of the ethical application of molecular biology, linking it with the rights of human beings. After studying literature, it might be observed that the Human Genome Project has generated several possibilities, such as the identification of genes associated with diseases with synergistic properties, but sometimes modifying behavior to genetically intervene in humans, bringing benefits or social harm. The big challenge is to decide what humanity wants on this giant leap.

Recovery of silver residues from dental amalgam

Dental amalgam residues are probably the most important chemical residues generated from clinical dental practice because of the presence of heavy metals among its constituents, mainly mercury and silver. OBJECTIVE: The purpose of this study was to develop an alternative method for the recovery of silver residues from dental amalgam. MATERIAL AND METHODS: The residue generated after vacuum distillation of dental amalgam for the separation of mercury was initially diluted with 32.5 percent HNO3, followed by precipitation with 20 percent NaCl. Sequentially, under constant heating and agitation with NaOH and sucrose, the sample was reduced to metallic silver. However, the processing time was too long, which turned this procedure not viable. In another sequence of experiments, the dilution was accomplished with concentrated HNO3 at 90ºC, followed by precipitation with 20 percent NaCl. After washing, the pellet was diluted with concentrated NH4OH, water and more NaCl in order to facilitate the reaction with the reducer. RESULTS: Ascorbic acid was efficiently used as reducer, allowing a fast reduction, thus making the procedure viable. CONCLUSIONS: The proposed methodology is of easy application and does not require sophisticated equipment or expensive reagents.

Optimizing the procedure for mercury recovery from dental amalgam

Mercury, as any other heavy metal, may cause environmental damages due to its accumulation and biotransformation. Dental offices, whether private or institutional, use dental amalgam as a restorative material on a daily basis. Dental amalgam is composed of mercury (50 percent), silver (30 percent) and other metals. Approximately 30 percent of the amalgam prepared in dental offices (0.6 g per capsule) are wasted and inadequately discarded without any treatment. Methods for mercury recovery have been proposed previously, using high temperatures through exposure to direct flame (650°C), long processing time, and hazardous reagents as potassium cyanide. The purpose of this study was to develop a method to replace the direct flame by an electrical mantle in the process of mercury recovery. Results showed an average mercury recovery of 90 percent from 2 kg of amalgam after 30 minutes of processing time, thus optimizing the procedure. The proposed modifications allowed a significant reduction in processing time and a mercury recovery with high purity. The modified process also provided minimization of operator exposure to physical, chemical and ergonomic hazards, representing a technological advance compared to the risks inherent to the original method. It also provided environmental health and economy of energy resources by replacing a finite energy source (fossil and organic) by a more environmentally appropriate electric source, resulting in significant improvement of the procedure for mercury recovery from dental amalgam.