Conjugated polymers nanostructured as smart interfaces for controlling the catalytic properties of enzymes.

The search for new molecular architectures to improve the efficiency of enzymes entrapped in ultrathin films is useful to enhance the effectiveness of biosensors. In this present work, conjugated polymers, based on thiophene and fluorine, were investigated to verify their suitability as matrices for the immobilization of urease. The copolymer poly[(9,9-dioctylfluorene)-co-thiophene], PDOF-co-Th was spread on the air-water interface forming stable Langmuir monolayers as determined by surface pressure-area isotherms, polarization-modulation reflection-absorption infrared spectroscopy (PM-IRRAS), and Brewster angle microscopy (BAM). Urease was incorporated in the floating monolayers being further transferred to solid supports as mixed Langmuir-Blodgett (LB) films. These films were then characterized with transfer ratio, fluorescence spectroscopy, PM-IRRAS and atomic force microscopy, confirming the co-transfer of the enzyme as well as its structuring in ß-sheets. The catalytic activity was detected for urease, with a lower reaction rate than that encountered for the homogeneous environment. This was attributed to conformational constraints imposed to the biomacromolecule entrapped in the polymeric matrix.

Defluorination of sodium fluoroacetate by bacteria from soil and plants in Brazil.

The aim of this work was to isolate and identify bacteria able to degrade sodium fluoroacetate from soil and plant samples collected in areas where the fluoroacetate-containing plants Mascagnia rigida and Palicourea aenofusca are found. The samples were cultivated in mineral medium added with 20 mmol L(-1) sodium fluoroacetate. Seven isolates were identified by 16S rRNA gene sequencing as Paenibacillus sp. (ECPB01), Burkholderia sp. (ECPB02), Cupriavidus sp. (ECPB03), Staphylococcus sp. (ECPB04), Ancylobacter sp. (ECPB05), Ralstonia sp. (ECPB06), and Stenotrophomonas sp. (ECPB07). All seven isolates degraded sodium-fluoroacetate-containing in the medium, reaching defluorination rate of fluoride ion of 20 mmol L(-1). Six of them are reported for the first time as able to degrade sodium fluoroacetate (SF). In the future, some of these microorganisms can be used to establish in the rumen an engineered bacterial population able to degrade sodium fluoroacetate and protect ruminants from the poisoning by this compound.

O papel do flúor sobre linhagens de células osteoblásticas de camundongos com densidades ósseas distintas: estudos em MC3T3-E1, C3H/HeJ e C57BL/6J / The role of fluoride on different osteoblastic cell line from different mice strains with distinct bone density: Study on MC3T3-E1, C3H/HeJ and C57BL/6J

Sabe-se que o flúor causa alterações químicas e celulares no osso, dependendo da dosagem e do tempo de exposição a esse elemento. Já foi demonstrado que alterações clínicas importantes, como a osteoporose, osteopetrose e esclerose óssea, podem ser geradas pela ingestão de flúor. Sabe-se que o flúor pode guiar os osteoblastos ao crescimento, sob doses e tempos de exposição específicos. A sensibilidade dos tecidos mineralizados ao fluoreto responde a mecanismos genéticos inerentes a cada população. Dentro de uma mesma espécie, diferentes linhagens apresentam um comportamento distinto frente a esse fármaco. Durante várias décadas, os estudos com fluoretos resumiram-se ao fluoreto de sódio, amplamente utilizado na prevenção das cáries dentárias. Recentemente, outras fontes de fluoretos como TiF4 e SnF2 têm sido buscadas, com intuito de potencializar as vantagens desse elemento. Porém não existem estudos ainda sobre o efeito do AlF3 sobre o tecido ósseo até a presente data. Desse modo, achamos oportuno investigar seu papel, quando administrado a células ósseas e para tal, investigamos a viabilidade e padrão de atividade das fosfatases desse sal (AlF3) quando administrado às células da linhagem pré-osteblástica MC3T3, em comparação ao NaF. Além disso, sabendo que diferentes células apresentam comportamento distinto ao tratamento com fluoretos, estudamos o papel do NaF quando administrado a duas linhagens celulares de camundongos com densidades ósseas distintas e com diferentes susceptibilidades ao fluoreto: C3H/HeJ e C57BL/6J (C3H e C57, alta e baixa densidades ósseas, respectivamente). As células também foram avaliadas quanto à viabilidade celular e ao perfil das fosfatases. Todos os resultados foram submetidos à Análise de Variância a três critérios e nos permitiu identificar que entre os sais de fluoreto, apenas o NaF promoveu alterações na viabilidade celular das células MC3T3. O AlF3 não exerceu influência na atividade da fosfatase alcalina...

It is well known that fluoride causes chemical and cellular alteration on bone tissue, depending on the dosage and time of exposure to this element. Several studies have been conducted to show that some bone diseases, such as osteoporosis, osteopetrosis and esclerosis, can occur as a consequence of the excessive fluoride uptake. Fluoride can lead osteoblast to proliferate, under certain conditions as time and dosage. The same way, excessive dosages of fluoride can alter protein activity in osteoblasts, by changing the expression of retated genes. Sensitivity of mineralized tissues to fluoride depends on a genetic background inherent to each population. Within the same specie, different lineages present distint behavior to the ingestion of this íon. Over several decades, many researches focused on the study of NaF as the only source of fluoride, once it is wide spread used to the prevention of dental caries. More recently, different sources of fluoride have been assessed, like TiF4 e SnF23 did not exibit influence over on alkaline phosphatase when pre-osteoblast cells are considered, but the effect of this fluoride salt on the activity of total and tartarate resistant acid phosphatases ocurrs on a dicotomic way. When we consider a mixed cell population, collected from calvária as for the C3H and C57 assays, NaF did interfered as with the proliferation rate as phosphatase activities on a very distinct fashion between the two lineages. Thus, it is possible to conclude that NaF is able to exert variable effects in different cell types and enzyme activities; on the other hand, AlF3 effects are more specific and surrounded in pre-osteblastic cells.

O papel do flúor sobre linhagens de células osteoblásticas de camundongos com densidades ósseas distintas: estudos em MC3T3-E1, C3H/HeJ e C57BL/6J / The role of fluoride on different osteoblastic cell line from different mice strains with distinct bone density: study on MC3T3-E1, C3H/HeJ and C57BL/6J

Sabe-se que o flúor causa alterações químicas e celulares no osso, dependendo da dosagem e do tempo de exposição a esse elemento. Já foi demonstrado que alterações clínicas importantes, como a osteoporose, osteopetrose e esclerose óssea, podem ser geradas pela ingestão de flúor. Sabe-se que o flúor pode guiar os osteoblastos ao crescimento, sob doses e tempos de exposição específicos. A sensibilidade dos tecidos mineralizados ao fluoreto responde a mecanismos genéticos inerentes a cada população. Dentro de uma mesma espécie, diferentes linhagens apresentam um comportamento distinto frente a esse fármaco. Durante várias décadas, os estudos com fluoretos resumiram-se ao fluoreto de sódio, amplamente utilizado na prevenção das cáries dentárias. Recentemente, outras fontes de fluoretos como TiF4 e SnF2 têm sido buscadas, com intuito de potencializar as vantagens desse elemento. Porém não existem estudos ainda sobre o efeito do AlF3 sobre o tecido ósseo até a presente data. Desse modo, achamos oportuno investigar seu papel, quando administrado a células ósseas e para tal, investigamos a viabilidade e padrão de atividade das fosfatases desse sal (AlF3) quando administrado às células da linhagem pré-osteblástica MC3T3, em comparação ao NaF. Além disso, sabendo que diferentes células apresentam comportamento distinto ao tratamento com fluoretos, estudamos o papel do NaF quando administrado a duas linhagens celulares de camundongos com densidades ósseas distintas e com diferentes susceptibilidades ao fluoreto: C3H/HeJ e C57BL/6J (C3H e C57, alta e baixa densidades ósseas, respectivamente). As células também foram avaliadas quanto à viabilidade celular e ao perfil das fosfatases. Todos os resultados foram submetidos à Análise de Variância a três critérios e nos permitiu identificar que entre os sais de fluoreto, apenas o NaF promoveu alterações na viabilidade celular das células MC3T3. O AlF3 não exerceu influência na atividade da fosfatase alcalina...

It is well known that fluoride causes chemical and cellular alteration on bone tissue, depending on the dosage and time of exposure to this element. Several studies have been conducted to show that some bone diseases, such as osteoporosis, osteopetrosis and esclerosis, can occur as a consequence of the excessive fluoride uptake. Fluoride can lead osteoblast to proliferate, under certain conditions as time and dosage. The same way, excessive dosages of fluoride can alter protein activity in osteoblasts, by changing the expression of retated genes. Sensitivity of mineralized tissues to fluoride depends on a genetic background inherent to each population. Within the same specie, different lineages present distint behavior to the ingestion of this íon. Over several decades, many researches focused on the study of NaF as the only source of fluoride, once it is wide spread used to the prevention of dental caries. More recently, different sources of fluoride have been assessed, like TiF4 e SnF23 did not exibit influence over on alkaline phosphatase when pre-osteoblast cells are considered, but the effect of this fluoride salt on the activity of total and tartarate resistant acid phosphatases ocurrs on a dicotomic way. When we consider a mixed cell population, collected from calvária as for the C3H and C57 assays, NaF did interfered as with the proliferation rate as phosphatase activities on a very distinct fashion between the two lineages. Thus, it is possible to conclude that NaF is able to exert variable effects in different cell types and enzyme activities; on the other hand, AlF3 effects are more specific and surrounded in pre-osteblastic cells.

Bone morphometry and differences in bone fluorine containing compounds in rats treated with NaF and MFP.

Sodium fluoride (NaF) and sodium monofluorophosphate (MFP) are drugs used to increase bone mass. They have been considered equivalent but the results of the treatments were not always coincident. Most studies have been carried out in osteoporotic women or ovariectomized rats pointing to the result in bone mass rather than at the mechanism of action. Convincing evidence indicates that pharmacokinetic of NaF is different from MFP. While only fluoride is found in bones and plasma of rats treated with NaF, in MFP-treated rats, there are also fluorine (F) bound to plasma alpha-macroglobulin and bone covalently bound F. A significant increase in bone mass of rats was observed after 30 days of treatment with NaF and MFP in young rats. This increase in bone mass correlates with the increase in number and thickness of trabeculas in cancellous bone. In the femur of MFP-treated rats, there was an increase in the inertia momentum of the diaphysis without changes in bone width. In addition, bone F content of MFP-treated animals is twice of the content of NaF-treated rats. This difference is the consequence of bone covalently bound F, which is absent in NaF-treated rats. In addition, alpha-macroglobulin was detected in noncollagenous bone matrix of MFP-treated rats. Although F in feces and plasma did not differ among treatments, the urinary excretion of F was lower in MFP than in NaF-treated rats, which is consistent with the higher bone F content.

Suscetibilidade genética para fluorose dentária: um estudo metabólico e proteômico com diferentes linhagens de camundongos / Genetic susceptibility for dental fluorosis: a metabolic and proteomic study with different strains of mice

A fluorose dentária é uma patologia que ocorre durante a formação dos dentes na presença de doses excessivas de fluoreto (F-). Os mecanismos pelos quais o Fprovoca a fluorose ainda são poucos conhecidos. A influência de fatores genéticos tem sido considerada na suscetibilidade/resistência do indivíduo em desenvolver a fluorose. Duas linhagens de camundongos (A/J e 129P3/J) com diferença na resistência ou suscetibilidade à fluorose dentária foram utilizadas para determinar se a suscetibilidade à fluorose pode ser explicada pela diferença no metabolismo e se há diferença no perfil protéico dos rins e urina destes animais. Para isso, um estudo metabólico foi conduzido com 18 camundongos A/J (suscetível) e 18 129P3 / J (resistente) após o desmame. Cada amostra foi dividida em 3 grupos, com diferentes concentrações de F- na água de beber (0, 10 e 50 ppm F). Uma vez que um estudo piloto revelou que os camundongos A/J ingeriam um maior volume de água quando comparado com o 129P3/J, a concentração de F- na água dada aos camundongos A/J foi ajustada semanalmente a fim de fornecer doses semelhantes de F- para ambas linhagens. Os animais foram mantidos em gaiolas metabólicas (n = 2/gaiola) por 7 semanas, com livre acesso à água e dieta de baixa ingestão de F- (0,95 ppm). A ingestão e excreção de F- foram calculadas, bem como os níveis de F- no plasma, no fêmur e no rim. O grau de fluorose dentária foi avaliado usando análise de fluorescência quantitativa (QLF) e exame clínico. Os perfis proteômicos renal e urinário foram examinados utilizando 2D-PAGE e coloração com azul de Coomassie.. Os dados do estudo metabólico foram testados para diferenças significativas pela ANOVA a 2 critérios (p <0,05). As imagens dos géis e as diferenças estatísticas (ANOVA, p<0,05) foram analisadas pelo programa Image Master Platinum 7.0. Os camundongos da linhagem A/J submetidos à alta concentração de fluoreto apresentaram um grau de fluorose significativamente maior quando comparado com a...

Dental fluorosis occurs during tooth formation when excessive doses of fluoride (F) are ingested. The mechanisms that underlie the pathogenesis of dental fluorosis are not known so far. The influence of genetic factors has been considered in individual susceptibility/resistance to develop fluorosis. Two inbred mice strains (A/J and 129P3/J) have been reported to have different susceptibilities to dental fluorosis. They were used in the present study to determine if the susceptibility to dental fluorosis can be explained by alterations in F metabolism and to evaluate if there is difference in the profile of protein expression in kidney and urine of these animals. For this, a metabolic study was conducted with 18 A/J (susceptible) and 18 129P3/J (resistant) weanling mice. Each strain was divided into 3 groups, with differed according to the F concentration given in the drinking water (0, 10 and 50 ppm F). Since a pilot study showed that the A/J mice drank a higher volume of water when compared with the 129P3/J, the F concentration in the water given to the A/J mice was weekly adjusted in order to provide similar F intakes for both strains. The mice were housed in metabolic cages (n=2/cage) for 7 weeks, with free access to water and low-F diet (0.95 ppm). F intake and excretion were calculated, as well as plasma, femur and kidney F levels. The degree of dental fluorosis was assessed using QLF and clinical examination. Renal and urinary proteome profiles were examined using 2D-PAGE and coomassie brilliant blue staining. Data were tested for significant differences by 2-way repeated-measures ANOVA (p<0.05). The gels images and statistical differences (ANOVA, p <0.05) were analyzed by the Image Master Platinum 7.0 software. Significantly higher QLF scores were observed for the A/J mice submitted to 50 ppm F. The total F intake did not significantly differ between the strains. The total F excretion was significantly higher for the A/J mice, due to the higher urinary...

Metabolismo e distribuição do flúor em ovinos jovens tratados cronicamente com fluoreto de sódio / Metabolism and distribution of fluor in lambs chronically treated with sodium fluoride

Este estudo teve por objetivo avaliar o metabolismo do flúor (F) em ovinos. Para tanto, utilizaram-se 12 animais, com cinco meses de idade, os quais receberam como dieta base 3 por cento do peso vivo de feno de alfafa e água ad libitum. Os animais foram divididos e constituíram um grupo Controle, que recebeu apenas sal iodado (5g de NaCl/animal + 0,2mg I/kg matéria seca) e, um grupo Tratado, que recebeu sal iodado adicionado de fluoreto de sódio (4,7mg F/kg de peso corporal). Esses sais foram administrados via sonda oro-esofágica, diariamente por um período de 150 dias. Para análise de F, coletaram-se amostras de sangue, urina e fezes e, ao fim do período experimental, após a eutanásia dos animais, coletou-se a glândula pineal e amostras de osso. Também nesta ocasião, coletou-se uma amostra de rim para exame histopatológico. Analisando-se os teores séricos, urinários e ósseos de F, verificou-se que foram significativamente superiores nos animais Tratados em relação aos Controles. Quanto ao F contido na glândula pineal, não houve diferença significativa entre os grupos. Na análise histológica do rim, não foram observadas alterações. Conclui-se que a administração crônica de flúor induz ao acúmulo desse elemento nos ossos, mesmo havendo um alto teor de cálcio na alimentação e esse acúmulo parece não ser nocivo aos animais. Em ovinos, a capacidade orgânica de acúmulo ósseo e excreção urinária do flúor é diferente de outras espécies animais.(AU)

The objective of the present study was to evaluate fluorine metabolism in growing lambs. Twelve 5-month-old male lambs maintained on alfalfa hay (3 percent BW) and non-fluorinated water ad libitum were used. Animals were allocated into Control, receiving 5g NaCl/animal/day + 0.2mg I/kg dry matter) and Treated group, receiving the same treatment plus sodium fluoride (4.7mg F/kg body weight). Mineral treatment was given by gavage, daily for 150 days. Blood, urine and fecal samples were collected during and the end of the experiment. At the end of treatment period animals were euthanized and kidney, pineal and bone samples were collected. Urine F was higher in treated animals throughout the experiment. Bone F levels were also increased in treated animals; pineal F content however, was not different between groups. Kidney histology revealed no differences. It is concluded that chronic F administration induces accumulation of the element in the skeleton. However such fact appears not to be detrimental to animals. Rates of F accumulation in bone and urine excretion obtained in other species can not be used in growing lambs.(AU)

Metabolismo e distribuição do flúor em ovinos jovens tratados cronicamente com fluoreto de sódio / Metabolism and distribution of fluor in lambs chronically treated with sodium fluoride

Este estudo teve por objetivo avaliar o metabolismo do flúor (F) em ovinos. Para tanto, utilizaram-se 12 animais, com cinco meses de idade, os quais receberam como dieta base 3 por cento do peso vivo de feno de alfafa e água ad libitum. Os animais foram divididos e constituíram um grupo Controle, que recebeu apenas sal iodado (5g de NaCl/animal + 0,2mg I/kg matéria seca) e, um grupo Tratado, que recebeu sal iodado adicionado de fluoreto de sódio (4,7mg F/kg de peso corporal). Esses sais foram administrados via sonda oro-esofágica, diariamente por um período de 150 dias. Para análise de F, coletaram-se amostras de sangue, urina e fezes e, ao fim do período experimental, após a eutanásia dos animais, coletou-se a glândula pineal e amostras de osso. Também nesta ocasião, coletou-se uma amostra de rim para exame histopatológico. Analisando-se os teores séricos, urinários e ósseos de F, verificou-se que foram significativamente superiores nos animais Tratados em relação aos Controles. Quanto ao F contido na glândula pineal, não houve diferença significativa entre os grupos. Na análise histológica do rim, não foram observadas alterações. Conclui-se que a administração crônica de flúor induz ao acúmulo desse elemento nos ossos, mesmo havendo um alto teor de cálcio na alimentação e esse acúmulo parece não ser nocivo aos animais. Em ovinos, a capacidade orgânica de acúmulo ósseo e excreção urinária do flúor é diferente de outras espécies animais.

The objective of the present study was to evaluate fluorine metabolism in growing lambs. Twelve 5-month-old male lambs maintained on alfalfa hay (3 percent BW) and non-fluorinated water ad libitum were used. Animals were allocated into Control, receiving 5g NaCl/animal/day + 0.2mg I/kg dry matter) and Treated group, receiving the same treatment plus sodium fluoride (4.7mg F/kg body weight). Mineral treatment was given by gavage, daily for 150 days. Blood, urine and fecal samples were collected during and the end of the experiment. At the end of treatment period animals were euthanized and kidney, pineal and bone samples were collected. Urine F was higher in treated animals throughout the experiment. Bone F levels were also increased in treated animals; pineal F content however, was not different between groups. Kidney histology revealed no differences. It is concluded that chronic F administration induces accumulation of the element in the skeleton. However such fact appears not to be detrimental to animals. Rates of F accumulation in bone and urine excretion obtained in other species can not be used in growing lambs.

A computational study of carbocations from oxidized metabolites of dibenzo[a,h]acridine and their fluorinated and methylated derivatives.

In a model computational study aimed at understanding structure-reactivity relationships and substituent effects on carbocation stability in aza-polycyclic aromatic hydrocarbons, the epoxides, diol epoxides, and the dihydrodiols of dibenzo[a,h]acridine (DB[a,h]ACR) were studied by density functional theory at the B3LYP/6-31G level. Bay region carbocations were formed via the O-protonated epoxides in barrierless processes. Relative carbocation stabilities were determined in the gas phase and in water as solvent (polarized continuum model method). Charge delocalization modes in the resulting carbocations were deduced by gauge-independent atomic orbitals (GIAO) NMR (based on Delta delta13C values) and via the natural population analysis (NPA)-derived changes in charges. Although the solvent decreases the exothermicity of the epoxide ring-opening reactions due to greater stabilization of the reactants, relative reactivity trends remain the same. Whereas fluorine substitution at ring positions bearing significant positive charge leads to carbocation stabilization by fluorine p-pi back-bonding, fluorine substitution at a ring position that presented negative charge density in the unsubstituted compound leads to inductive destabilization. Methylated derivatives exhibit less sensitivity to substituent effects as compared to the fluorinated analogues. A bay region methyl group produces structural distortion, and this deviation from planarity destabilizes the epoxide, favoring ring opening. Relative energies, changes in NPA charges, and GIAO NMR data in the resulting "benzylic" carbocations are examined collectively and discussed, taking into account the available biological activity data on these compounds.

El uso de fluoruro en la prevención de caries, parte I: caries dental, mecanismo de acción y metabolismo del fluoruro / Fluoride use in dental caries prevention, part I: dental caries, mechanism of action and metabolism of fluoride

Este artículo revisa los actuales conceptos sobre los mecanismos de la formación de la caries dental y la influencia de la presencia de fluoruro (F) en la cavidad oral especialmente en el fluido de la placa y en los procesos de remineralización. Se comenta un esquema sencillo del metabolismo del fluoruro junto a algunos conceptos nuevos sobre la influencia de la edad y de las dosis diarias de F en la retención corporal y excreción renal de F

Metabolism of the complex monofluorophosphate-alpha 2-macroglobulin in the rat.

Sodium monofluorophosphate (MFP) is a drug used in the treatment of primary osteoporosis. Following the intake of MFP, a small fraction of the drug is absorbed intact and forms a complex with alpha 2-macroglobulin (MFP-alpha 2M) inactivating the antiproteasic activity of the globulin. The complex has been shown to occur in the serum of rats and human being. This paper reports data on the metabolism of this complex in the rat. In vitro experiments showed that liver and bone tissue remove MFP-alpha 2M from the incubation medium. When the experiments were pursued beyond the time needed to reduce the complex concentration to very low levels, fluorine (F) reappears in the medium in two forms: bound to low molecular weight macromolecule/s (2,200 +/- 600 Da) and as ionic F. Concentrations of these F fractions increase while that of the complex decreases as a function of time. In vitro, uptake of the complex by liver or bone tissue was not affected by the presence of colchicine or methylamine. These drugs, however, inhibited intracellular metabolism of the complex, as indicated by the impairment of the return of F species to the extracellular space and the increase in F content of the tissue. The cellular receptors responsible for the uptake of the complex in liver and bone are insensitive to low concentration of calcium and inhibited by polyinosinic acid[5']. These features characterize the "scavenger" receptor, one of the two receptor types known to remove inactive alpha 2M from the circulation. Injection of polyinosinic acid [5'] to living rats also hindered the disappearance of the complex from serum. It is concluded that the metabolism of the MFP-alpha 2M complex involves binding to receptors, uptake by cells, lysosomal degradation and return of F bound to low molecular weight macromolecule/s to the extracellular space. It is assumed, however, that inorganic F is the final product of lysosomal hydrolysis of the protein moiety.

Metabolism of the complex monofluorophosphate-alpha2-macroglobulin in the rat

Sodium monofluorophosphate (MFP) is a drug used in the treatment of primary osteoporosis. Following the intake of MFP, a small fraction of the drug is absorbed intact and forms a complex with alpha2-macroglobulin (MFP-alpha2M) inactivating the antiproteasic activity of the globulin. The complex has been shown to occur in the serum of rats and human being. This paper reports data on the metabolism of this complex in the rat. In vitro experiments showed that liver and bone tissue remove MFP-alpha2M from the incubation medium. When the experiments were pursued beyond the time needed to reduce the complex concentration to very low levels, fluorine (F) reappears in the medium in two forms: bound to low molecular weight macromolecule/s (2,200 + 600 Da) and as ionic F. Concentrations of these F fractions increase while that of the complex decreases as a function of time. In vitro, uptake of the complex by liver or bone tissue was not affected by the presence of colchicine or methylamine. These drugs, however, inhibited intracellular metabolism of the complex, as indicated by the impairment of the return of F species to the extracellular space and the increase in F content of the tissue. The cellular receptors responsible for the uptake of the complex in liver and bone are insensitive to low concentration of calcium and inhibited by polyinosinic acid[5']. These features characterize the "scavenger" receptor, one of the two receptor types known to remove inactive alpha2M from the circulation. Injection of polyinosinic acid [5'] to living rats also hindered the disappearance of the complex from serum. It is concluded that the metabolism of the MFP-alpha2M complex involves binding to receptors, uptake by cells, lysosomal degradation and return of F bound to low molecular weight macromolecule/s to the extracelular space. It is assumed, however, that inorganic F is the final product of lysosomal hydrolysis of the protein moiety.

Metabolism of the complex monofluorophosphate-alpha2-macroglobulin in the rat

Sodium monofluorophosphate (MFP) is a drug used in the treatment of primary osteoporosis. Following the intake of MFP, a small fraction of the drug is absorbed intact and forms a complex with alpha2-macroglobulin (MFP-alpha2M) inactivating the antiproteasic activity of the globulin. The complex has been shown to occur in the serum of rats and human being. This paper reports data on the metabolism of this complex in the rat. In vitro experiments showed that liver and bone tissue remove MFP-alpha2M from the incubation medium. When the experiments were pursued beyond the time needed to reduce the complex concentration to very low levels, fluorine (F) reappears in the medium in two forms: bound to low molecular weight macromolecule/s (2,200 + 600 Da) and as ionic F. Concentrations of these F fractions increase while that of the complex decreases as a function of time. In vitro, uptake of the complex by liver or bone tissue was not affected by the presence of colchicine or methylamine. These drugs, however, inhibited intracellular metabolism of the complex, as indicated by the impairment of the return of F species to the extracellular space and the increase in F content of the tissue. The cellular receptors responsible for the uptake of the complex in liver and bone are insensitive to low concentration of calcium and inhibited by polyinosinic acid[5]. These features characterize the "scavenger" receptor, one of the two receptor types known to remove inactive alpha2M from the circulation. Injection of polyinosinic acid [5] to living rats also hindered the disappearance of the complex from serum. It is concluded that the metabolism of the MFP-alpha2M complex involves binding to receptors, uptake by cells, lysosomal degradation and return of F bound to low molecular weight macromolecule/s to the extracelular space. It is assumed, however, that inorganic F is the final product of lysosomal hydrolysis of the protein moiety. (AU)

Fluorosis dental en comunidades rurales localizadas en zonas con elevada altitud / Dental fluorosis in high-altitude rural communities

El propósito del presente estudio fue estimar la prevalencia y severidad de fluorosis dental en cuatro zonas rurales de la región centro-sur de la República Mexicana, ubicadas a más de 2000 mts. sobre el nivel del mar. El índice de Dean fue utilizado para evaluar el nivel de fluorosis dental de la población. La concentración de flúor en agua en cada una de las cuatro comunidades seleccionadas fue de 0.60, 1.4, 1.6 y 2.8 ppm. Se examinó un total de 331 escolares de 9 a 12 años de edad. La prevalencia de fluorosis dental tuvo un valor superior al 90 por ciento en las cuatro comunidades estudiadas. Se observó un incremento en el índice comunitario de fluorosis (ICF) al incrementarse la concentración de flúor, el ICF más bajo fue de 0.62 y el más alto de 2.93. La prevalencia y severidad de la fluorosis encontrada en la población de estudio fue más elevada que la observada en escolares de países desarrollados que habitan en zonas con concentraciones similares de flúor en agua. La altura de la zona es un factor que posiblemente contribuye a la elevada prevalencia y severidad de fluorosis dental detectada en los niños mexicanos examinados

Specific fluorogenic substrates for neprilysin (neutral endopeptidase, EC 3.4.24.11) which are highly resistant to serine- and metalloproteases.

Two intramolecularly quenched fluorogenic peptides containing o-aminobenzoyl (Abz) and ethylenediamine 2,4-dinitrophenyl (EDDnp) groups at amino- and carboxyl-terminal amino acid residues, Abz-DArg-Arg-Leu-EDDnp (Abz-DRRL-EDDnp) and Abz-DArg-Arg-Phe-EDDnp (Abz-DRRF-EDDnp), were selectively hydrolyzed by neutral endopeptidase (NEP, enkephalinase, neprilysin, EC 3.4.24.11) at the Arg-Leu and Arg-Phe bonds, respectively. The kinetic parameters for the NEP-catalyzed hydrolysis of Abz-DRRL-EDDnp and Abz-DRRF-EDDnp were K(m) = 2.8 microM, kcat = 5.3 min-1, kcat/K(m) = 2 min-1 microM-1 and K(m) = 5.0 microM, kcat = 7.0 min-1, kcat/K(m) = 1.4 min-1 microM-1, respectively. The high specificity of these substrates was demonstrated by their resistance to hydrolysis by metalloproteases [thermolysin (EC 3.4.24.2), angiotensin-converting enzyme (ACE; EC 3.4.24.15)], serineproteases [trypsin (EC 3.4.21.4), alpha-chymotrypsin (EC 3.4.21.1)] and proteases present in tissue homogenates from kidney, lung, brain and testis. The blocked amino- and carboxyl-terminal amino acids protected these substrates against the action of aminopeptidases, carboxypeptidases and ACE. Furthermore, DR amino acids ensured total protection of Abz-DRRL-EDDnp and Abz-DRRF-EDDnp against the action of thermolysin and trypsin. Leu-EDDnp and Phe-EDDnp were resistant to hydrolysis by alpha-chymotrypsin. The high specificity of these substrates suggests their use for specific NEP assays in crude enzyme preparations.

Avaliacao metabolica do fluor pre-natal / Prenatal fluoride - metabolic evaluation

O uso do fluor tem sido o principal meio utilizado para o controle da carie dentaria. Entretanto, com relacao a administracao pre-natal, alem do beneficio ser questionavel, as formulacoes contem calcio, podendo haver reducao do aproveitamento de ambos. Assim o objetivo deste trabalho foi uma avaliacao metabolica de fluor indicado para gestantes. O delineamento experimentalfoi do tipo cruzado, utilizando-se oito voluntarias e dois tratamentos com produtos comerciais, um dos quais continha essencialmente fluor e outro na forma de complexos com sais mineirais e vitaminas. Em cada etapa do experimento, metade das voluntarias ingeria um tipo de medicamento e outro, sendo feito a inversao apos uma semana. Saliva coletada das voluntarias antes e pelo tempo de duas horas apos a ingestao dos comprimidos. Urina total foi coletada antes e apos os tratamentos. Nos comprimidos, determinou-se: a- quantidade de fluor soluvel em acido fraco ("suco gastrico") e forte. As dosagens de ion fluor foram feitas com eletrodo especifico. Orion 96-90. Os resultados mostraram que houve uma reducao significativa de aproveitamento de fluor quando da administracao do produto na forma decomplexos. Observou-se tambem uma correspondencia entre os parametros metabolicos da avaliacao e a quantidade de fluor soluvel nos medicamentos. Considerando asincertezas a respeito da eficiencia anticarie do fluor pre-natal e os resultados desta pesquisa, sugere-se que estes medicamentos devam ser contra-indicados

Relação Ca:MFP na reatividade do flúor de dentifrícios: estudo "in vitro" do seu efeito com o esmalte dental humano / Ca:MFP relation on fluoride reactivity of dentifrices: an \"in vitro\" study of its effect on the human dental enamel

O objetivo deste trabalho foi estudar o efeito de cálcio (Ca) na atividade do flúor (MFP) de dentifrícios. Para tal foram formulados três dentifrícios contendo sílica como abrasivo. Destes dentifrícios, um deles era placebo de Ca e MFP, outro continha 1450 ppm F (MFP) sendo placebo de Ca, e o terceiro continha 0,45//de CaCl/2 e 1450 ppm F (MFP), relação Ca: MFP = 0,50. A atividade destes dentifrícios foi comparada com o Colgate MFP-Ca do mercado. Concluiu-se que o Colgate MFP-Ca não apresenta efeito aditivo de atividade laboratorial o que sugere que com maior razão o mesmo deve ser esperado "in vivo", pois sua relação solúvel Ca:MFP é de 0,02