RESUMO
Fluoride (F) can induce changes in the expression of several liver proteins. It is suggested that these changes are dose- and time-dependent. The objective of this study was to analyze the effect of different F concentrations and exposure times to this ion on the pattern of protein expression in the liver of rats. Thirt-six 21-day-old male Wistar rats were divided into 2 groups (nâ¯=â¯18) according to the treatment duration (20 or 60â¯days). Each of these groups was then divided into 3 subgroups (nâ¯=â¯6) according to the concentration of F administered in drinking water, as follows: 0â¯mg/L (control), 15â¯mg/L or 50â¯mg/L. After the experiment periods, the animals were anesthetized and the liver and blood were collected. F was analyzed in plasma and liver. Part of the liver was fixed for histological analysis. Liver proteins were extracted and prepared for quantitative label-free mass spectrometry analysis. F concentrations in plasma and liver were significantly higher in the group treated with 50â¯mg /L in comparison with control, regardless the time of exposure. Histological alterations in the liver were more evident in the subgroups treated for 20â¯days. The proteomic analysis revealed changes in proteins related to endoplasmic reticulum and mitochondrial oxidative stress, mitochondrial alteration, apoptosis and cellular respiration upon exposure to F. The results reinforce previous findings showing that the effects of F in the liver are dose- and time-dependent and provide the molecular basis for understanding the evolution of these effects.
Assuntos
Água Potável/efeitos adversos , Fluoretos/sangue , Fluoretos/toxicidade , Fígado/efeitos dos fármacos , Fígado/metabolismo , Animais , Relação Dose-Resposta a Droga , Água Potável/administração & dosagem , Fluoretos/administração & dosagem , Masculino , Ratos , Ratos Wistar , Fatores de TempoRESUMO
The objective of this study was to evaluate markers of oxidative stress in the brains of rats exposed to lead acetate (Pb(C2 H3 O2 )2 ), either associated or not associated with ferrous sulfate (FeSO4 ). A total of 36 weaning rats (Rattus norvegicus) were divided into 6 groups of six animals and exposed to lead acetate for six weeks. In the control group (control), the animals received deionized water. The Pb260 and Pb260 + Fe received 260 µM lead acetate, and the Pb1050 and Pb1050 + Fe received 1050 µM lead acetate. The Pb260 + Fe and Pb1050 + Fe were supplemented with 20 mg of ferrous sulfate/Kg body weight every 2 days. Group Fe received deionized water and ferrous sulfate. The rat brains were collected to analyze the enzymatic activity of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and the concentration of reduced glutathione (GSH), lipid peroxidation (TBARS), and total antioxidant substance (TAS) (DPPH⢠technique). The activity of SOD and GPx in the experimental groups decreased compared to the control, together with the concentration of GSH (p < 0.05). For CAT analysis, SOD tended to increase in concentration in the experimental groups without a concomitant exposure to FeSO4 , whereas GPx showed a slight tendency to increase in activity compared to the control. For TAS-DPPH⢠, there was a decrease in the experimental groups (p < 0.05). According to the results, SOD, GPx, and GSH were affected by lead acetate and exposure to ferrous sulfate changed this dynamic. However, further studies are needed to verify whether ferrous sulfate acts as a protectant against the toxic effects of lead. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 813-822, 2017.
Assuntos
Antioxidantes/metabolismo , Encéfalo/efeitos dos fármacos , Compostos Ferrosos/farmacologia , Compostos Organometálicos/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Animais , Antioxidantes/química , Peso Corporal/efeitos dos fármacos , Encéfalo/metabolismo , Catalase/metabolismo , Glutationa/metabolismo , Glutationa Peroxidase/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Masculino , Compostos Organometálicos/análise , Compostos Organometálicos/sangue , Ratos , Ratos Wistar , Superóxido Dismutase/metabolismoRESUMO
Alkaline phosphatase (AP) isozymes are present in a wide range of species from bacteria to man and are capable of dephosphorylation and transphosphorylation of a wide spectrum of substrates in vitro. In humans, four AP isozymes have been identified-one tissue-nonspecific (TNAP) and three tissue-specific-named according to the tissue of their predominant expression: intestinal (IAP), placental (PLAP) and germ cell (GCAP) APs. Modulation of activity of the different AP isozymes may have therapeutic implications in distinct diseases and cellular processes. For instance, changes in the level of IAP activity can affect gut mucosa tolerance to microbial invasion due to the ability of IAP to detoxify bacterial endotoxins, alter the absorption of fatty acids and affect ectopurinergic regulation of duodenal bicarbonate secretion. To identify isozyme selective modulators of the human and mouse IAPs, we developed a series of murine duodenal IAP (Akp3-encoded dIAP isozyme), human IAP (hIAP), PLAP, and TNAP assays. High throughput screening and subsequent SAR efforts generated a potent inhibitor of dIAP, ML260, with specificity for the Akp3-, compared to the Akp5- and Akp6-encoded mouse isozymes.
Assuntos
Acetanilidas/química , Acetanilidas/farmacologia , Fosfatase Alcalina/antagonistas & inibidores , Sulfonamidas/química , Sulfonamidas/farmacologia , Acetanilidas/isolamento & purificação , Animais , Ativação Enzimática/efeitos dos fármacos , Inibidores Enzimáticos/química , Inibidores Enzimáticos/isolamento & purificação , Inibidores Enzimáticos/farmacologia , Humanos , Camundongos , Isoformas de Proteínas/química , Sulfonamidas/isolamento & purificaçãoRESUMO
The objective of this study was to evaluate comparatively the effect of fluoride in the expression of the receptor activator of nuclear factor kappa B ligand (RANKL), osteoprotegerin (OPG) and tartrate-resistant acid phosphatase (TRAP) in alveolar bone repair in rats. We used 3 groups of male Wistar rats (n = 5/group), which received drinking water containing different doses of F (NaF): 0, 5 and 50 ppm, for 60 days before the incisors extraction. The upper incisors were extracted and the animals were killed 7, 14, 21 and 30 days after extraction. The hemi-maxillae were collected for microscopic examination (histomorphometric and immunostaining for RANKL, OPG and TRAP). Histomorphometric analysis confirmed an increase in the volume density of neoformed bone between 7 and 30 days for groups control, 5 and 50 ppm of F, with a concomitant decrease in the volume density of connective tissue and blood clot. Higher blood clot for groups 5 and 50 ppm of F at 30 days was observed. The RANKL and OPG expressions were not changed by chronic exposure to fluoride in the drinking water during the studied periods; on the other hand, TRAP expression was changed (at 7 days) by chronic exposure to fluoride (p < 0.05). It was concluded that F in high concentrations can slow the blood clot remission and bone repair, and alter the TRAP expression in the beginning of the bone tissue repair. However, a better understanding about this blood clot remission phenomenon is required.
Assuntos
Fosfatase Ácida/metabolismo , Regeneração Óssea , Fluoretos/administração & dosagem , Isoenzimas/metabolismo , Osteoprotegerina/metabolismo , Ligante RANK/metabolismo , Animais , Masculino , Ratos , Ratos Wistar , Fosfatase Ácida Resistente a TartaratoRESUMO
Fluoride (F) can induce changes in the expression of several liver proteins, most of them localized in the mitochondria and its effect is dose- and time-dependent. This study analyzed the effect of distinct F concentrations and exposure periods on the mitochondrial activity of complex I-III and II-III in the liver. Thirty-six 21-day-old male Wistar rats were divided into 2 groups (n = 18) according to the duration of the treatment (20 or 60 days). They were subdivided into 3 subgroups (n = 6) according to the concentration of F (0 mg/L, 15 mg/L or 50 mg/L). After the experimental periods, the animals were anesthetized, liver mitochondria were isolated and stored for activity analyses. The determination of complexes II-III and I-III was based on the reduction of cytochrome c3+ to cytochrome c2+ performed spectrophotometrically. Bioinformatics analyses were performed using data from a previous study (Pereira et al., 2018). The mitochondrial complex I-III was significantly activated in the groups treated with 50 mgF/L for 20 days and 15 mgF/L for 60 days. The complex II-III was significantly reduced in the group treated with the higher F dose for 60 days. The networks indicated more changes in mitochondrial proteins in the group treated with the higher dose for 20 days; the reduction is probably linked to the activation of the complex I-III. The reduction in the complex II-III upon exposure to the higher F dose in the long term might be part of an adaptative mechanism of the body to counteract the deleterious effects of this ion on the energy metabolism.
RESUMO
PURPOSE: The aim of this in situ double-blind randomised crossover study was to investigate the effect of calcium (Ca) pre-rinse on the composition of plaque and on enamel prior to the use of fluoride (F) dentifrice. MATERIALS AND METHODS: During four phases (14 days each) of this study, 10 volunteers had agreed to wear dental appliances containing two healthy bovine enamel blocks. A fresh solution containing 20% weight/volume (w/v) sucrose was dripped on the enamel blocks ex vivo for 5 min three times a day. Subsequently, the appliances were replaced in the mouth, and the volunteers rinsed their mouth with 10 mL of a Ca (150 mmol/L) or a placebo rinse (1 min). In sequence, a slurry (1:3 w/v) of F (1030 ppm) or placebo dentifrice was dripped onto the blocks ex vivo for 1 min. During this time, the volunteers brushed their teeth with the respective dentifrice. The appliances were replaced in the mouth, and the volunteers rinsed their mouth with water. The plaque formed on the blocks was analysed for F and Ca. The enamel demineralisation as well as the incorporation of F on enamel was evaluated by cross-sectional microhardness and alkali-soluble F analysis, respectively. Data were tested using analysis of variance (P < 0.05). RESULTS: The Ca pre-rinse prior to the use of the F dentifrice led to a three- and sixfold increase in the plaque F and Ca concentrations, respectively. It also did not have any additive effect on the F content on the enamel and the demineralisation of the enamel, in comparison with the use of F dentifrice alone. CONCLUSIONS: A Ca lactate rinse used prior to the F dentifrice was able to change the mineral content in the plaque, but it was unable to prevent enamel demineralisation.
Assuntos
Cálcio/uso terapêutico , Cariostáticos/uso terapêutico , Esmalte Dentário/efeitos dos fármacos , Placa Dentária/química , Dentifrícios/uso terapêutico , Fluoretos/uso terapêutico , Antissépticos Bucais/uso terapêutico , Animais , Cálcio/administração & dosagem , Cálcio/análise , Compostos de Cálcio/administração & dosagem , Compostos de Cálcio/uso terapêutico , Cariogênicos/efeitos adversos , Cariostáticos/administração & dosagem , Cariostáticos/análise , Bovinos , Estudos Cross-Over , Esmalte Dentário/metabolismo , Placa Dentária/etiologia , Dentifrícios/administração & dosagem , Método Duplo-Cego , Feminino , Fluoretos/administração & dosagem , Fluoretos/análise , Dureza , Humanos , Lactatos/administração & dosagem , Lactatos/uso terapêutico , Masculino , Antissépticos Bucais/administração & dosagem , Placebos , Solubilidade , Sacarose/efeitos adversos , Desmineralização do Dente/etiologia , Adulto JovemRESUMO
OBJECTIVE: This in situ blind crossover study investigated the effect of calcium (Ca) rinse prior to the use fluoride (F) dentifrice on remineralisation of artificially demineralised enamel and on the composition of biofilm. DESIGN: During four phases of 14 days, 10 volunteers wore appliances containing two artificially demineralised bovine enamel blocks. Three times a day, they rinsed with 10 mL of Ca (150 mM) or placebo rinse (1 min). A slurry (1:3, w/v) of F (1030 ppm) or placebo dentifrice was dripped onto the blocks. During 1 min, the volunteers brushed their teeth with the respective dentifrice. The appliance was replaced into the mouth and the volunteers rinsed with water. The biofilm formed on the blocks was analysed for F and Ca. Enamel alterations were evaluated by the percentage of surface microhardness change (%SMHC), cross-sectional microhardness (% mineral volume) and alkali-soluble F analysis. Data were analysed by ANOVA (p<0.05). RESULTS: The use of the Ca pre-rinse before the F dentifrice produced a six- and four-fold increase in biofilm F and Ca concentrations, respectively. For enamel, the remineralisation was significantly improved by the Ca pre-rinse when compared to the other treatments. There was a significantly higher concentration of alkali-soluble F in enamel when the F dentifrice was used, but the Ca pre-rinse did not have any significant additive effect. CONCLUSIONS: According to our protocol, the Ca pre-rinse significantly increased biofilm F concentration and, regardless the use of F dentifrice, significantly enhanced the remineralisation of artificially demineralised enamel.
Assuntos
Biofilmes/efeitos dos fármacos , Cálcio/uso terapêutico , Cariostáticos/uso terapêutico , Esmalte Dentário/efeitos dos fármacos , Dentifrícios/uso terapêutico , Remineralização Dentária , Adulto , Cálcio/administração & dosagem , Estudos Cross-Over , Esmalte Dentário/ultraestrutura , Feminino , Fluoretos/análise , Fluoretos/uso terapêutico , Humanos , Masculino , Antissépticos Bucais , Método Simples-CegoRESUMO
We grouped mice [strains: C57BL/6J (n=32) and C3H/HeJ (n=32)] to address the influence of bone density on fluoride's (F's) biological effects. These animals received low-fluoride food and water containing 0 (control group) or 50ppm of F for up to 28days. The upper left central incisor was extracted, and the left maxilla was collected at 7, 14, 21, and 28days for histological and histomorphometric analysis to estimate bone neoformation. Our results showed bone neoformation in all of the evaluated groups, with the presence of bone islets invading the center of the alveoli when replacing the existing connective tissue. Curiously, this biological phenomenon was more evident in the C57BL/6J strain. The histomorphometric analysis confirmed the histological findings in relation to the amount of new bone tissue and showed a decrease in C3H/HeJ mice (control group). Altogether, our results showed differential effects of fluoride bone metabolism, confirming a genetic component in susceptibility to the effects of fluoride.
Assuntos
Densidade Óssea/fisiologia , Remodelação Óssea/efeitos dos fármacos , Osso e Ossos/efeitos dos fármacos , Fluoretos/farmacologia , Animais , Densidade Óssea/efeitos dos fármacos , Osso e Ossos/fisiologia , Fluoretos/administração & dosagem , Fluoretos/química , Masculino , Camundongos , Camundongos Endogâmicos C3H , Camundongos Endogâmicos C57BLRESUMO
BACKGROUND: Here, we evaluated the relationship of diet and F-induced oxidative stress to lipid metabolism in the liver of rats eating normocaloric or hypercaloric diets for two time periods (20 or 60 days). METHODS: Seventy-two 21-day-old Wistar rats were divided into 2 groups (n = 36) based on the type of diet they were eating; each of these groups was then further divided into another two groups (n = 18) based on the time periods of either 20 or 60 days, for a total of four groups. Each of these was divided into 3 subgroups (n = 6 animals/subgroup), dependent on the dose of F administered in the drinking water (0 mg/L(control), 15 mg/L or 50 mg/L). After the experimental period, blood samples and the liver were collected. Plasma samples were analyzed for HDL, cholesterol and triglycerides. Western blots were performed to probe for GRP78, Erp29, SOD2, Apo-E and SREBP in hepatic tissues. RESULTS: As expected,the expression of target proteins involved in oxidative stress increased in the F-treated groups, especially in liver tissue obtained from animals eating a hypercaloric diet. Most changes in the lipid levels and pathological conditions were seen earlier in the time period, at day 20. The morphometric analyses showed a reduction in steatosis in groups on ahypercaloric diet and treated with 50 mg F/L compared to the control, while no changes were obtained in normocaloric-fed rats. Accordingly, plasma TG was reduced in the F-treated group. The reduced expression of Apo-E in a time- and diet-dependent pattern may account for the particular decrease in steatosis in hypercaloric-fed F-treated rats. CONCLUSIONS: These results suggest that F changes liver lipid homeostasis, possibly because of the induction of oxidative stress, which seems to be higher in animals fed hypercaloric diets.
Assuntos
Dieta , Ingestão de Energia , Fluoretos/farmacologia , Metabolismo dos Lipídeos/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Animais , Biomarcadores , Estresse do Retículo Endoplasmático , Lipídeos/sangue , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , RatosRESUMO
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.
Assuntos
Genética/ética , Genética/legislação & jurisprudência , Genoma Humano , HumanosRESUMO
UNLABELLED: 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% HNO3, followed by precipitation with 20% 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 90 degrees C, followed by precipitation with 20% 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.
Assuntos
Amálgama Dentário/química , Resíduos Odontológicos , Recuperação e Remediação Ambiental/métodos , Prata/isolamento & purificação , Ácido Ascórbico/química , Precipitação Fracionada/métodos , Eliminação de Resíduos de Serviços de Saúde , Ácido Nítrico/química , Substâncias Redutoras/química , Cloreto de Sódio/química , Hidróxido de Sódio/química , Sacarose/químicaRESUMO
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%), silver (30%) and other metals. Approximately 30% 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 degrees 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% 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.
Assuntos
Amálgama Dentário/química , Resíduos Odontológicos/análise , Exposição Ambiental/prevenção & controle , Eliminação de Resíduos de Serviços de Saúde/métodos , Mercúrio/análise , Gerenciamento de Resíduos/métodos , Brasil , Consultórios Odontológicos , Restauração Dentária Permanente , Saúde Ambiental , Monitoramento Ambiental , Poluentes Ambientais/análise , Resíduos Perigosos/análise , Humanos , Mercúrio/isolamento & purificação , Intoxicação por Mercúrio , Medição de RiscoRESUMO
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.
RESUMO
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.
RESUMO
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.
Assuntos
Humanos , Genética , Genética/legislação & jurisprudência , Genoma HumanoRESUMO
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.
Assuntos
Resíduos Odontológicos , Amálgama Dentário/química , Recuperação e Remediação Ambiental/métodos , Prata/isolamento & purificação , Ácido Ascórbico/química , Precipitação Fracionada/métodos , Eliminação de Resíduos de Serviços de Saúde , Ácido Nítrico/química , Substâncias Redutoras/química , Cloreto de Sódio/química , Hidróxido de Sódio/química , Sacarose/químicaRESUMO
A Bioquímica, como outras áreas básicas, tem se desenvolvido de forma muito rápida e a produção desse conhecimento se deve em grande parte à PósGraduação e à Iniciação Científica (IC). Por isso, nos últimos anos, muitos alunos de graduação têm procurado desenvolver projetos nas disciplinas básicas (histologia, bioquímica, farmacologia e outras), gerando um aumento na procura por projetos de Iniciação Científica. No entanto, o perfil, expectativas e motivações dos alunos que desenvolvem projetos de pesquisa em áreas básicas, bem como qual a visão dos mesmos acerca da contribuição da IC para o seu desenvolvimento acadêmico e profissional não têm sido descritos. Para isso foi proposto um questionário simples, composto de questões de múltipla escolha e questões abertas, que abordaram os motivos que levaram o aluno à procura pelo laboratório de Bioquímica, bem como a visão do aluno acerca da contribui- ção da experiência advinda da IC para o seu desenvolvimento acadêmico e profissional. Os questionários foram aplicados aos alunos que desenvolveram projetos de IC no Laboratório de Bioquímica do Departamento de Ciências Biológicas da Faculdade de Odontologia de Bauru Universidade de São Paulo, no período de 2006-2008. Após a análise dos dados obtidos, pode-se concluir que a uma parcela significativa dos alunos que fazem IC (41%) procura esse tipo de projeto para se diferenciar dos demais alunos da graduação. Segundo os entrevistados os conhecimentos adquiridos durante o processo de pesquisa colaboraram para sua formação profissional (100%) e no processo de aprendizagem como um todo (AU).
Similar to other basic areas, Biochemistry has developed very quickly, and the production of knowledge in these areas can be attributed largely to graduate studies and scientific initiation (SI). With this in mind, many undergraduate students have sought to develop projects in basic disciplines (histology, biochemistry, pharmacology and others) in recent years, increasing the demand for Scientific Initiation projects. Nevertheless, the profile, expectations and motivations of students developing research projects in basic areas, as well as their views regarding the contribution of SI toward their academic and professional development has not been related. To this end, a simple questionnaire was proposed, with multiple choice and open questions, addressing the reasons that led students to seek the biochemistry lab and students' viewpoints regarding the contribution of the experience gained in SI toward their academic and professional development. The questionnaires were applied to students who were developing SI projects in the Biological Sciences Department of the Bauru Dentistry College of São Paulo University between 2006 and 2008. After analyzing the data obtained, we can conclude that a meaningful portion of the students that take SI (41%) seek this type of project to distinguish themselves from other undergraduate students. According to those interviewed, the knowledge acquired during the research process contributed to their professional training (100%) and to the learning process as a whole (AU).
Assuntos
Humanos , Masculino , Feminino , Bioquímica/educação , Pesquisa Básica , Aprendizagem , Estudantes , Inquéritos e QuestionáriosRESUMO
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.
Assuntos
Humanos , Amálgama Dentário/química , Resíduos Odontológicos/análise , Exposição Ambiental/prevenção & controle , Eliminação de Resíduos de Serviços de Saúde/métodos , Mercúrio/análise , Gerenciamento de Resíduos/métodos , Brasil , Consultórios Odontológicos , Restauração Dentária Permanente , Saúde Ambiental , Monitoramento Ambiental , Poluentes Ambientais/análise , Resíduos Perigosos/análise , Intoxicação por Mercúrio , Mercúrio/isolamento & purificação , Medição de RiscoRESUMO
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.
Assuntos
Animais , Masculino , Ratos , Antioxidantes/química , Fluoretos/administração & dosagem , Fluoretos/toxicidade , Oxidantes/química , Antioxidantes/metabolismo , Fígado , Fígado/metabolismo , Fluoretos/metabolismo , Miocárdio/metabolismo , Oxidantes/metabolismo , Ratos Wistar , Rim , Rim/metabolismo , Fatores de TempoRESUMO
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.