Development of a sodium fluoride and stannous chloride-containing gel for treatment of dental erosion

Resumo Este estudo desenvolveu e testou géis experimentais contendo íons fluoreto (F-) e estanho (Sn2+) para o controle da erosão dentária. Os espécimes polidos, de esmalte e dentina, foram previamente erodidos (solução de ácido cítrico a 1%, 10 min) e alocados aleatoriamente em 5 grupos (n = 10): Placebo - gel de hidroxipropilmetilcelulose (HMC); F + Sn + HMC - 7.500 ppm F- / 15.000 ppm Sn2+; F + HMC - 7.500 ppm F-; Gel de flúor fosfato acidulado comercial (12.300 ppm F-); e Controle - sem tratamento. Após o tratamento (aplicado por 60 s), os espécimes foram submetidos a uma ciclagem de erosão-remineralização (5 min em solução de ácido cítrico a 0,3%, 60 min em saliva artificial, 4 × / dia, 20 dias). A perda de superfície (SL, em µm) foi determinada após o 5º, 10º e 20º dias de ciclagem (α = 0,05). Para o esmalte, após 5 e 10 dias, o F + Sn + HMC apresentou a menor PS, não diferindo do gel comercial. Após 20 dias, não foram encontradas diferenças entre os grupos comercial, F + HMC e F + Sn + HMC. O placebo não diferiu do controle em nenhum momento, e ambos os grupos apresentaram a maior PS, comparado aos demais grupos. Para dentina, no 5º dia , F + Sn + HMC, F + HMC e comercial não diferiram significativamente, apresentando menor PS que o grupo controle e placebo. No 10º dia, F+Sn+HMC e comercial apresentaram a menor PS comparado ao grupo controle e placebo. No 20º dia, apenas o gel comercial apresentou PS menor que o controle e o placebo. Assim, o gel experimental F + Sn + HMC foi capaz de controlar a progressão da erosão dentária.

Abstract: This study synthesized and tested experimental gels containing fluoride (F-) and stannous (Sn2+) ions for the control of dental erosion. Enamel and dentin polished specimens were eroded (1% citric acid solution, 10 min) and randomly allocated into 5 groups (n=10): Placebo - Hydroxypropyl Methylcellulose (HMC) gel; F+Sn+HMC - 7,500 ppm F- / 15,000 ppm Sn2+; F+HMC - 7,500 ppm F-; Commercial acidulated phosphate fluoride gel (12,300 ppm F-); and Control - no treatment. After treatment (applied for 60 s), specimens underwent an erosion-remineralization cycling (5 min in 0.3% citric acid solution, 60 min in artificial saliva, 4×/day, 20 days). Surface loss (SL, in µm) was determined after the 5th, 10th and 20th days of cycling (α=0.05). For enamel, after 5 and 10 days, F+Sn+HMC presented the lowest SL, which did not differ from the commercial gel. After 20 days, no differences were found between commercial, F+HMC, and F+Sn+HMC groups. Placebo did not differ from the control at any time points, and both groups presented the highest SL when compared to the other groups. For dentin, on the 5th day, F+Sn+HMC, F+HMC and commercial did not differ significantly, showing lower SL than the control and the placebo. On the 10th day, F+Sn+HMC and commercial presented the lowest SL compared to control and placebo. After 20 days, only the commercial gel showed lower SL than the control and placebo. Thus, the experimental F+Sn+HMC gel was able to control the progression of tooth erosion.

In-vitro evaluation of the anti-cariogenic effect of a hybrid coating associated with encapsulated sodium fluoride and stannous chloride in nanoclays on enamel

Abstract Objective The aim of this study is to test, in vitro, the anti-cariogenic effect of experimental hybrid coatings, with nano clays of halloysite or bentonite, loaded with sodium fluoride or with a combination of sodium fluoride and stannous chloride, respectively. Methodology The varnish Fluor Protector (1,000 ppm of F-) was used as positive control and no treatment was the negative control. Enamel specimens (5 mm × 5 mm) were obtained from bovine teeth. The specimens (n=10) had their surfaces divided into two halves (5 mm × 2.5 mm each), in which one half received one of the treatments (Hybrid; Hybrid + NaF; Hybrid + NaF + SnCl2; Hybrid + NaF Loaded; Hybrid + NaF + SnCl2 Loaded). The specimens were submitted to a cariogenic challenge using a biofilm model (S. mutans UA159, for 5 days). Enamel surfaces both under and adjacent to the treated area were analyzed for mineral loss and lesion depth, by transverse microradiography. The pH of the medium was measured twice a day, and the fluoride release was analyzed. Additional specimens were submitted to confocal analysis. Results Data were statistically analyzed by two-way ANOVA followed by Tukey test (α=0.05). None of hybrid groups were able to reduce the lesion depth; the Hybrid + NaF group, however, was able to reduce mineral loss differing from the negative control (p=0.008). The groups showed no significant difference in the pH measurement and fluoride release. Confocal analysis confirmed that for all groups the biofilm growth was similar. Conclusion None of the hybrid groups reduced lesion depth, but the Hybrid + NaF group was able to promote protection against mineral loss.

Effects of different toothpastes on the prevention of erosion in composite resin and glass ionomer cement enamel and dentin restorations

Abstract Objective This study aimed to evaluate the effects of different toothpastes on the surface wear of enamel, dentin, composite resin (CR), and resin-modified glass ionomer cement (RMGIC), and to perform a topographic analysis of the surfaces, based on representative images generated by atomic force microscopy (AFM) after erosion-abrasion cycles. Methodology One hundred and forty bovine incisors were collected and divided into two groups: 72 enamel and 72 dentin blocks (4×4 mm). Half of the specimens were restored with CR (Filtek Z350 XT) and the other half with RMGIC (Fuji II LC). Then, samples were submitted to a demineralization cycle (5 days, 4×2 min/day, 1% citric acid, pH 3.2) and exposed to three different toothpastes (2×15 s/day): without fluoride (WF, n=12), sodium fluoride-based (NaF, n=12), and stannous fluoride-based (SnF2, n=12). Surface wear, as well as restoration interfaces wear, were investigated by profilometry of the dental substrates and restorative materials. All representative surfaces underwent AFM analysis. Data were analyzed by two-way analysis of variance and Tukey's tests (α=0.05). Results NaF-based toothpaste caused the greater dentin surface wear (p<0.05). Toothpastes affected only enamel-restoration interfaces. AFM analysis showed precipitate formation in dentinal tubules caused by the use of fluoride toothpastes. Conclusions NaF-based toothpastes had no protective effect on enamel adjacent to CR and RMGIC against erosion-abrasion challenges, nor on dentin adjacent to RMGIC material. SnF2-based toothpastes caused more damage to interfaces between enamel and RMGIC.

Efeito de fluoretos presentes em dentifrícios na prevenção da erosão de restaurações de resina composta e cimento de ionômero de vidro de esmalte e dentina erodidos / Effect of fluorides preseot in tootbpastes on tbe preventing erosion from enameJ and dentin eroded of composite resin and glass ionomer cement restorations

O objetivo desse estudo foi avaliar o desgaste, as propriedades mecânicas, topografia e composição química dos substratos dentários e materiais restauradores após ciclo erosivo/abrasivo, utilizando diferentes dentifrícios. Foram utilizados 244 blocos, sendo 122 de esmalte e 122 blocos de dentina, medindo 4 x 4 mm, obtidos a partir de incisivos bovinos que foram cortados e polidos. Cada amostra continha um bloco de esmalte e um de dentina, entre os blocos foram confeccionadas restaurações com cimento de ionômero de vidro modificado por resina (CIVMR) e resina composta (RC). Após as restaurações, a hemiface de cada amostra foi recoberta com verniz ácido-resistente, afim de produzir o lado controle. Esses dois grupos foram subdivididos em três grupos, de acordo com o dentifrício utilizado no processo de abrasão: SF - sem flúor (controle negativo), NaF - com fluoreto de sódio 1450 ppm de F (controle positivo) e SnF2 - com fluoreto de estanho 1100 ppm de F. O ácido cítrico a 0,05 M, pH= 3.2, foi utilizado nos ciclos de erosão, sendo realizados 4x/dia, 2 minutos cada, com intervalos de 1 hora entre cada ciclo. Os espécimes foram submetidos à abrasão (2x/dia, ao final do primeiro e último ciclo erosivo/dia), aplicando o slurry (1:3) sobre as amostras por 2 minutos, seguidos de 15 segundos de escovação por espécime (200 g por 15 s), ao longo de 5 dias. Na sequência, o verniz ácido resistente foi removido da hemiface de cada amostra e estas foram analisadas quanto ao desgaste das superfícies através de perfilometria (n=12), microdureza, apenas dos materiais restauradores (n =12), topografia por microscopia de força atômica (AFM) (n=2), nanodureza (H) e módulo de elasticidade (Er) (n=5), composição química através de energia dispersiva de raios-X (EDS) (n=3), microscopia Raman (n= 5). Os dados de perfilometria, microdureza dos materiais restauradores, (H / Er) e EDS e Raman foram submetidos a ANOVA dois fatores medidas repetidas e teste de Tukey (p< 0,05). Em relação às imagens de AFM foram analisadas apenas qualitativamente. O dentifrício NaF promoveu o maior desgaste nas superfícies dentinárias adjacentes ao CIVMR e RC. Apenas as interfaces adjacentes ao esmalte sofreram influência do dentifrício. Os mais baixos valores de microdureza foram observados para CIVMR quando se utilizou o dentifrício SnF2 (p < 0,05). Em relação aos valores de H e Er, pode-se notar que não houve diferenças entre os dentifrícios (p> 0,05), apenas entre as superfícies dentro de cada dentifrício (p< 0,05). Em relação às superfícies controle e erodida, apenas RC manteve seus valores constantes após erosão (p> 0,05). Em relação à composição química, os substratos dentários erodidos mostraram menores concentrações de cálcio e fosfato, enquanto para a superfície do material ionomérico houve uma diminuição de flúor e aumento de cálcio para as superfícies erodidas; as superfícies de resina composta mostraram-se inalteradas em sua composição química após os desafios erosivos (p > 0.05). Os dentifrícios não foram capazes de promover diferença nas propriedades mecânicas das superfícies após ciclo erosivo-abrasivo. Entretanto, promoveram diferenças quanto ao desgaste, composição química e topografia das superfícies, à exceção das superfícies de resina composta(AU)

The aim of this study was to evaluate the wear, mechanical properties, topography and chemical composition of dental substrates and restorative materiais after erosive / abrasive cycle using different toothpastes. A total of 244 blocks were used: 122 enamel and 122 dentin blocks, measuring 4 x 4 mm, obtained from bovine incisors that were cut and polished. Each sample contained one enamel and one dentin blocks, between them were made restorations with resin modified glass ionomer cement (RMGIC) and composite resin (CR). After restorations, the hemiface of each sample was coated with acid-resistant vamish to produce the contrai side. These two groups were subdivided into three groups according to the toothpaste used in the abrasion process: SF - no fluoride (negative control), NaF - sodium fluoride with 1450 ppm F (positive control) and SnF2 - stannous fluoride with 1100 ppm F. The 0.05 M citric acid, pH = 3.2, was used in the erosion cycles, being performed 4x / day, 2 minutes each, with 1 hour intervals between each cycle. The specimens were subjected to abrasion (2x / day at the end of the first and last erosive cycle / day), applying the slurry (1:3) to the samples for 2 minutes, followed by 15 seconds of brushing per specimen (200 g per 15 s) over 5 days. Next, acid resistant vamish was removed from the hemiface of each sample and these were analyzed for surface wear by profilometry (n = 12), microhardness of restorative materiais only (n = 12), atomic force microscopy (AFM) topography (n = 2), nanohardness (H) and modulus of elasticity (Er) (n = 5), chemical composition by X-ray dispersive energy (EDS) (n = 3), Raman microscopy (n = 5). The profilometry, microhardness of the restorative materiais, (H / Er) and EDS and Raman data were submitted to two-way repeated measures ANOVA and Tukey test (p <0.05). Regarding the AFM images were analyzed only qualitatively. NaF toothpaste promoted higher wear on dentin surfaces adjacent to RMGIC and CR. Only the interfaces adjacent to the enamel were influenced by the toothpaste. The lowest microhardness values were observed for MVICR when using the SnF2 dentifrice (p <0.05). Regarding H and Er values, there were no differences among the toothpastes (p> 0.05), only among the surfaces into each toothpaste (p< 0.05). ln relation to control and eroded surfaces, only CR maintened constant values after erosive-abrasive cycles (p> 0.05). Regarding the chemical composition, the eroded dental substrates presented lower calcium and phosphate concentrations, while for the surface of the ionomeric material there was a decrease of fluoride and calcium increase for the eroded suraces. Composite resin surfaces were unchanged in their chemical composition after erosion challenges (p> 0.05). The toothpastes were not able to promote difference in the mechanical properties of surfac.es after erosive-abrasive cycle. However, promoted differences in surface wear, chemical composition and topography, except for composite resin surfaces(AU)

Clinical evaluation of the anti-gingivitis efficacy of a novel stabilized stannous-containing sodium fluoride dentifrice / 实用口腔医学杂志

Objective: To evaluate the anti-gingivitis efficacy of a novel stabilized stannous-containing sodium fluoride dentifrice. Methods: A randomized, controlled and double blind clinical study was conducted. 156 adults with gingivitis were enrolled and randomly assigned to experimental group(group of novel stabilized stannous-containing sodium fluoride dentifrice, n = 51), positive control group (group of Yunnan Baiyao dentifrice, n = 54) and negative control group (group of Crest dentifrice, n = 51). Gingival health was assessed using Mazza Modification of the Papillary Bleeding Index(Mazza GI) at Baseline, day 3 and week 4 and pocket depth was evaluated at baseline and week 4, respectively. Results: At day 3 and week 4, the experimental and positive control groups exhibited lower clinical parameters than the negative control group(P＜ 0. 000 1). At week 4, the mean Mazza GI scores and PD of the experimental group were significantly lower than those of the positive control group(P＜ 0. 05). Conclusion: The novel stannous-containing sodium fluoride dentifrice has anti-gingivitis efficacy.

Enhanced efficiency of stannous penetration and lipopolysaccharide neutralization by a novel stabilized stannous-containing sodium fluoride dentifrice / 实用口腔医学杂志

Objective:To evaluate the dental biofilm penetration efficiency of a novel stabilized stannous-containing sodium fluoride dentifric(EXP) and its lipopolysaccharide (LPS) neutralization efficiency.Methods:A controlled,randomized,examiner-blind in situ clinical trial was conducted with the treatment of PBS(control),EXP and a marketed stannous-containing sodium fluoride dentifrice (MKD).Fluorescent dye,fluorescent probe and fluorescence colocalization were used for sample examination and analysis.Results:EXP offered better stannous penetration into the biofilm than MKD and PBS(P ＜0.05),as well as greater LPS neutralization efficiency(P ＜0.05).There was a 96.52％ overlap of stannous ions and bounded LPS at the same sites treated by EXP.Conclusion:EXP is more effective than MKD in the delivery of stannous into the biofilm and in the neutralization of LPS.

The effects of a stannous-containing sodium fluoride dentifrice and crisscross bristle toothbrush in the management of gingivitis and dental plaque observed by an office-based study / 实用口腔医学杂志

Objective:To investigate the effects of a stannous-containing sodium fluoride dentifrice and crisscross bristle manual tooth-brush in the management of dental plaque and gingivitis.Methods:249 cases with gingivitis were enrolled in an office-based study. The study was unsupervised and single-centered with open-label and self-control.At baseline,gingival health and plaque coverage were assessed by dentists using categorical scales.Participants were given stannous containing sodium fluoride dentifrice and crisscross bristle design manual brush,and were instructed to use the products by manufacturer's usage instructions twice daily for 30 days.At the end of 30 days,plaque and gingivitis were reassessed using the same categorical scales.Results:232 participants(1 78 females and 54 males) completed the study.Gingivitis data of 5 cases and dental plaque data of 3 cases were not judgable.After 30 days of product use,226 cases(99%)showed noticeable improvement in their gingival health;227(96%)cases showed improvement in overnight plaque cover-age.Conclusion:Stannous-containing sodium fluoride dentifrice in combination with crisscross bristle toothbrush is effective in the management of gingivitis and dental plaque.

Anti toxic effect of broccoli extract on stannous dichloride toxicity / Efeito antitóxico do extrato de brócolis na toxicidade do dicloreto de estanho

PURPOSE: Since Technetium-99m (99mTc) has favorable physical and chemical characteristics, it is widely used radioisotope in Nuclear Medicine. However, stannous dichloride (SnCl2) has been widely used as a reducing agent in labeling procedure of pharmaceutical with radionuclide, it has been realized that SnCl2 have genotoxic and cytotoxic effects on biological systems. In previous studies, it has been shown that some herbal extract can reduce genotoxic and cytotoxic effects of SnCl2. In the present study, it is aimed to evaluate the effect of the broccoli extract on the survival of E. coli ATCC 25922 strain against to toxic effects of SnCl2. METHODS: Broccoli was extracted with methanol extraction. HPLC and TLC analysis of broccoli extract were performed. Then antitoxicity and dose response assays were performed on bacterial strain. RESULTS: The broccoli extract had dose dependent protective effect against SnCl2 toxic effect on E. coli. CONCLUSIONS: The consumption of broccoli may alter the stannous dichloride toxicity. Broccoli extract may use as a new protective strategies against the toxic effect of SnCl2 on patients who were taken 99mTc radiopharmaceuticals.

OBJETIVO: Em face de suas características físico-químicas, o Tecnécio-99m (99mTc) é um radiofármaco amplamente utilizado na Medicina Nuclear. Todavia, o dicloreto de estanho (SnCl2) tem sido largamente aplicado como um agente redutor no procedimento farmacêutico de marcação com radionuclídeos. Constatou-se que o SnCl2 apresenta efeitos genotóxicos e citotóxicos nos sistemas biológicos. Em estudos prévios, foi demonstrado que alguns extratos de ervas podem reduzir tais efeitos. O estudo atual objetivou avaliar os efeitos do extrato de brócolis na sobrevida da cepa E. coli ATCC 25922, exposta ao efeito tóxico do SnCl2. MÉTODOS: O extrato de brócolis foi obtido mediante extração com metanol. Analises com HPLC e TLC foram efetuadas. Avaliou-se a antitoxicidade e realizou-se um ensaio dose-resposta para uma cepa de bactérias. RESULTADOS: O extrato de brócolis mostrou um efeito protetor dose dependente para os efeitos tóxicos do SnCl2 sobre a E. coli. CONCLUSÕES: O consumo de brócolis pode alterar a toxicidade do dicloreto de estanho. O extrato de brócolis pode ser utilizado como uma nova estratégia para proteção de pacientes contra os efeitos tóxicos do SnCl2, nos quais foi administrado o radiofármaco Tecnécio-99m.

How to Combat White Spot Lesion In Orthodonticcases - Review Study.

All over the world fixed orthodontic cases face a common problem –enamel hypoplasia that is white spot lesion. It can be remineralised by brushing with fluoridated toothpaste, fluoride mouth rinses and topical application of fluoride gel/foam. Efficiency of remineralisation is enhanced with daily usage of 0.05%(225ppm) sodium fluoride or 0.2% (900ppm) weekly; or with 0.4%Stannous Fluoride gel. But Stannous Fluoride stains the enamel. Enamel can also be remineralised with casein phosphopeptide-amorphous calcium phosphate(CCP-ACP). Remineralised white spot lesion can be bleached to mask the colour and can be microabraded followed by bleaching leaving a highly polished surface with calcium phosphate packed into the interprismatic enamel surface area.

Biodistribución y farmacocinética de 99mTc-ciprofloxacina obtenida de una formulación modificada / Biokinetics performance of 99mTc-ciprofloxacin obtained from a new formulation

El propósito de la presente investigación fue evaluar el comportamiento biocinético de la 99mTc-ciprofloxacina obtenida de una nueva formulación. Un ensayo in vitro y un modelo de infección experimental demostraron su afinidad por bacterias vivas. La vida media en sangre fue de 5,89 +/- 0,85 horas. La biodistribución mostró alta acumulación en músculos infectados y baja en tejidos sanos.

The aim of the present investigation was to evaluate the biokinetics performance of 99mTc-ciprofloxacin obtained from a new formulation. Both in vitro assays and experimental infection models demonstrated its affinity for viable bacteria.Half life in blood was 5.89 +/- 0.85 hours. The biodistribution showed high accumulation on infected muscles and low on healthy tissues.

Participação de enzimas de reparo por excisão de bases na restauração de lesões induzidas pela associação da radiação ultravioleta A e cloreto estanoso em Escherichia coli / Participation of repair enzyme for base excision in lesions restoration induced by the combination of A ultraviolet radiation and stannous chloride in Escherichia coli

O cloreto estanoso (SnCI2) e a radiação ultravioleta A (UVA) são agentes que lesam diversas estruturas celulares, inclusive o DNA, principalmente pela geração de espécies reativas de oxigênio. O objetivo deste trabalho foi estudar a mutagênese e o reparo das lesões produzidas pela combinação do UVA, na condição de pré-iluminação, com o SnCI2. Avaliou-se a ação de enzimas do reparo por excisão de bases (BER), em Escherichia coli (E. coli), por eletroforese em gel alcalino de agarose e sobrevivência bacteriana. Também se estudou a indução do sistema SoxRS pelo cromoteste, e a mutagênese pelo teste de Ames. De acordo com os resultados: i)o UVA induziu quebras no DNA das cepas testadas e os mutantes fpg-nfo e fpg apresentaram maior retardo no reparo das lesões; ii) o SnCI2 induziu mais quebras que o UVA e os mutantes nfo e fpg mostraram maior dificuldade em reparar as lesões; iii) o UVA+SnCI2 provocou mais quebras que o SnCI2 e os mutantes nfo e fpg também apresentaram maior lentidão no reparo das lesões; iv) o UVA não inativou as cepas testadas; v) as cepas nfo e fpg foram as mais sensíveis ao SnCI2; vi) o UVA+SnCI2 provocou maior letalidade em todas as cepas testadas, em relação ao SnCI2, e os mutantes nfo e fpg também foram os mais sensíveis ao tratamento com ambos os agentes; vii) a transformação dos mutantes nfo com o plasmídio pBW21 (nfo+) e dos mutantes fpg com o plasmídio pFPG (fpg+) aumentou a sobrevivência das cepas aos tratamentos com SnCI2 e UVA+SnCI2; viii) o SnCI2 induziu o sistema SoxRS; ix) o SnCI2, UVA e UVA+SnCI2 não induziram mutagênese; x) o reparo das lesões parece ser preferencialmente realizado pelas proteínas Fpg e Nfo.

Stannous chloride (SnCI2) and ultraviolet radiation A (UVA) are able to induce lesions in different cellular structures, including DNA, manly through ROS generation. The aim of this work was to study the mutagenesis and repair of lesions induced by the association of UVA (pre treatment) with SnCI2. It was evaluated the action of base excision repair (BER) enzymes in Escherichia coli (E. coli) by alkaline gel electrophoresis and bacterial survival. It was also evaluated the SoxRS system induction by chromotest and mutagenesis through the Ames test. According to the results: i) UVA induced DNA strand breaks in all strains and fpg-nfo and fpg mutants showed greater delay in the repair of lesions; ii) SnCI2 induced more breaks than UVA and nfo and fpg mutants showed more difficult to repair the damage; iii) UVA + SnCI2 caused more breaks than the SnCI2 and nfo and fpg mutants also showed a slowest repair of injuries; iv) UVA did not inactivate any bacterial strains tested; v) nfo and fpg strains were more sensitive to SnCI2; vi) UVA + SnCI2 caused higher mortality in all strains tested, when compared to SnCI2, and, again, nfo and fpg mutants were the most sensitives to the treatment with both agents; vii) the transformation of nfo mutant with the plasmid pBW21 (nfo+) and fpg mutants with plasmid pFPG (fpg+) increased the survival of the strains to SnCI2 and UVA + SnCI2 treatments; viii) SnCI2 was able to induce SoxRS system; ix) SnCI2, UVA + SnCI2 and UVA did not induce mutagenesis; x) damage repair seems to be preferentially performed by Fpg and Nfo proteins.

Biological effects of an aqueous extract of Salix alba on the survival of Escherichia coli AB1157 cultures submitted to the action of stannous chloride

Stannous chloride (SnC12) is used in nuclear medicine as a reducing agent to obtain technetium-99m-radiopharmaceuticals. It have been reported that natural products might reduce the genotoxic and cytotoxic effects related to SnC12. This work evaluated the biological effects of an aqueous extract of Salix alba on the survival of Escherichia coli (E. coli) AB1157 (wild type) cultures submitted to the action of SnC12. E. coli AB1157 cultures (exponential growth phase) were collected by centrifugation, washed and resuspended in 0.9 percentNaCl. Samples were incubated in water bath shaker with: (a) SnC12 (25mg/ml), (b)Salix alba extract(11.6mg/ml) and (c)SnC12(25mg/ml) + Salix alba extract (11.6mg/ml). Incubation with 0.9 percent NaCl was also carried out (control). At 60 min intervals, aliquots were withdrawn, diluted, spread onto Petri dishes with solid LB medium and incubated overnight. The colonies formed were counted and the survival fractions calculated. The extract was not able to protect the E. coli cultures against the lesive action of SnC12. The extract also did not interfere with the survival of the cultures. It suggested that the substances present in the Salix alba aqueous extract did not interfere strongly with cellular metabolism and did not alter the survival fractions of E. coli AB 1157. It is speculated that this extract cannot interfere with the generation of free radicals, the possible main agent responsible for SnC12 lesive action.

Alkaline gel electrophoresis assay to detect DNA strand breaks and repair mechanisms in Escherichia coli

Reactive oxygen species (ROS) can induce lesions in different cellular targets, including DNA. Stannous chloride (SnCl2) is a ROS generator, leading to lethality in Escherichia coli (E. coli), with the base excision repair (BER) mechanism playing a role in this process. Many techniques have been developed to detect genotoxicity, as comet assay, in eukaryotic cells, and plasmid DNA agarose gel electrophoresis. In this study, an adaptation of the alkaline gel electrophoresis method was carried out to ascertain the induction of strand breaks by SnCl2 in bacterial DNA, from E. coli BER mutants, and its repair pathway. Results obtained show that SnCl2 was able to induce DNA strand breaks in all strains tested. Moreover, endonuclease IV and exonuclease III play a role in DNA repair. On the whole, data has shown that the alkaline gel electrophoresis assay could be used both for studying DNA strand breaks induction and for associated repair mechanisms.

Espécies reativas de oxigênio (ERO) podem induzir lesões em diferentes alvos celulares, incluindo o DNA. O cloreto estanoso (SnCl2) é um gerador de ERO que induz letalidade em E. coli, sendo o reparo por excisão de bases (BER) um mecanismo importante neste processo. Técnicas como o ensaio cometa (em eucariotos) e a eletroforese de DNA plasmidial em gel de agarose têm sido utilizadas para detectar genotoxicidade. No presente estudo, uma adaptação do método de eletroforese em gel alcalino de agarose foi usada para verificar a indução de quebras, pelo SnCl2, no DNA de E. coli, bem como a participação de enzimas do BER na restauração das lesões. Os resultados mostraram que o SnCl2 induziu quebras no DNA de todas as cepas testadas. Além disso, endonuclease IV e exonuclease III estão envolvidas na reparação dos danos. Em resumo, os dados obtidos indicam que a metodologia de eletroforese em gel alcalino de agarose pode ser empregada tanto para o estudo de quebras no DNA, quanto para avaliação dos mecanismos de reparação associados.

The effect of an extract from Ganoderma lucidum (reishi) on the labeling of blood constituents with technetium-99m and on the survival of Escherichia coli

This study evaluated effects of an aqueous extract of Ganoderma lucidum (reishi) on the labeling of bloodconstituents with technetium-99m (99mTc) and on the survival of cultures of Escherichia coli treated with stannouschloride. Blood samples from Wistar rats were treated with reishi extract, radiolabeling procedure was performed,plasma (P), blood cells (BC) and insoluble (IF) and soluble (SF) fractions of P and BC were separated. Theradioactivity was counted for the determination of the percentages of radioactivity (%ATI). Cultures of Escherichia coli AB1157 were treated with stannous chloride in the presence and absence of reishi extract. Blood samples and bacterial cultures treated with NaCl 0.9% were used as controls. Data indicated that reishi extract alteredsignificantly (p<0.05) the %ATI of P, BC, IF-P, SF-P, IF-BC and SF-BC, as well as increased the survival of bacterial cultures treated with stannous chloride. Our results suggest that reishi extract could present a redox/chelating action, altering the labeling of blood constituents with 99mTc and protecting bacterial cultures against oxidative damage induced by stannous chloride.

Este estudo avaliou efeitos de um extrato de Ganoderma lucidum (reishi) na marcação de constituintes sangüíneos com tecnécio-99m (99mTc) e na sobrevivência de culturas deEscherichia coli tratadas com cloreto estanoso. Amostras de sangue de ratos Wistar foram tratadas com extrato de reishi, o procedimento de radiomarcação foi realizado, plasma (P), célulassangüíneas (CS) e frações insolúvel (FI) e solúvel (FS) de P e CS foram separadas e a radioatividade foi contada para determinação das porcentagens deradioatividade (%ATI). Culturas de Escherichia coli AB1157 foram tratadas com cloreto estanoso na presença e ausência do extrato de reishi. Amostras de sangue e culturas bacterianas tratadas com NaCl 0.9% foram usadas como controles. Dados indicaram que o extrato de reishi alterou significativamente (p<0,05) a %ATI de P, CS, FIP, FS-P, FI-CS e FS-CS, bem como, aumentou a sobrevivência de culturas bacterianas tratadas comcloreto estanoso. Nossos resultados sugerem que o extrato de reishi poderia apresentar ação redox/quelante alterando a marcação de constituintes sangüíneos com 99mTc e protegendoculturas bacterianas contra lesões oxidativas induzidas pelo cloreto estanoso.

Influence of an extract of Juglans regia on the growth of Escherichia coli, on the electrophoretic profile of plasmid DNA and on the radiolabeling of blood constituents

The aim of this work was to study the influence of a walnut (Juglans regia) extract on the growth of Escherichia coli (E. coli) AB1157, on the plasmid DNA topology and on the labeling of blood constituents with technetium-99m (99mTc). An E. coli AB1157 culture, in stationary phase, was incubated with walnut and the growth of the culture was evaluated by optical density at 600 nm for 7 hours. Plasmid DNA samples were incubated with SnCl2 in presence or absence of walnut for 40 minutes, 0.8 percent agarose gel electrophoresis was performed, the gel was stained and the plasmid topological forms were visualized. Blood samples from Wistar rats were incubated with walnut extract and an assay of labeling of blood constituents with technetium-99m (99mTc) was performed. Blood cells and plasma were separated. The radioactivity in each fraction was counted and percentage of incorporated radioactivity ( percentATI) was determined. The results presented an inhibitory action of the growth of the E. coli AB1157 culture, no protective action of the walnut extract in plasmid DNA treated with SnCl2. Moreover, walnut was also not capable to induce modifications in the DNA mobility in agarose gel but walnut was capable to decrease the distribution of 99mTc on the blood cell compartment. In conclusion, our experimental data suggest that in the walnut extract has substances with an effect on the growth of E. coli culture, a potential action to increase the SnCl2 effect on plasmid DNA and also is capable to alter the distribution of 99mTc on the blood cell compartment probably due to redoxi properties.

O objetivo desse trabalho foi estudar a influência de um extrato de nogueira (Juglans regia) no crescimento de Escherichia coli (E. coli) AB1157, na topologia do DNA plasmidial e na marcação de constituintes sanguíneos com tecnécio-99m (99mTc). Uma cultura de E. coli AB1157, em faseestacionária, foi incubada com nogueira e o crescimento da cultura foi avaliado por densidade óptica a 600nm por 7 horas. Amostras de DNA plasmidial foram incubadas com SnCl2 napresença ou ausência de nogueira por 40 minutos, a eletroforese em agarose 0.8% foi realizada, o gel foi corado e as formas topológicas do plasmídioforam visualizadas. Amostras de sangue de ratos Wistar foram incubadas com extrato de nogueira e um ensaio de marcação de constituintes sanguíneos com tecnécio-99m (99mTc) foirealizado. Células sanguíneas e plasma foram separadas. A radioatividade em cada fração foi contada e a percentagem de radioatividade incorporada (%ATI) foi determinada. Os resultados apresentaram uma ação inibitória docrescimento da cultura de E. coli AB1157, nenhuma ação protetora do extrato de nogueira em DNA plasmidial tratado com SnCl2. Além disso,na nogueira também não foi capaz de induzir modificações na mobilidade do DNA em gel de agarose, mas a nogueira foi capaz de diminuir a distribuição de 99mTc no compartimento sanguíneocelular. Concluindo, nosso resultado experimental sugere que no extrato de nogueira existem substâncias com um efeito no crescimento de cultura de E. coli, uma ação capaz de aumentar oefeito do SnCl2 no DNA plasmidial e também ser capaz de alterar a distribuição de 99mTc no compartimento sanguíneo celular provavelmentedevido a propriedades redoxi.

Influence of an aqueous extract of Hypericum perforatum (Hypericin) on the survival of Escherichia coli AB1157 and on the electrophoretic mobility of pBSK plasmid DNA / Influência de um extrato aquoso de Hypericum perforatum (Hipericina) na sobreviência de Escherichia coli AB1157 e na mobilidade eletroforética de DNA plasmidial pBSK

Hiperico (Hypericum perforatum or St John's worth) has been widely used as an herbal medicine to treat depression. Hypericin is the main chemical compound of hiperico. Stannous chloride (SnCl2) is the most used reducing agent in nuclear medicine. The aim of this work was to verify the effect of a hiperico extract on the survival of Escherichia coli AB1157 and on the plasmid DNA topology. Exponentially E. coli AB1157 cultures were incubated with SnCl2 in the presence or absence of hypericin. Aliquots were spread onto Petri dishes containing solidified rich medium, the colonies units were counted after overnight and the survival fraction was calculated. Plasmid DNA samples were incubated with SnCl2 in presence or absence of hypericin extract during 40 minutes, 0.8 percent agarose gel electrophoresis was performed, the gel was stained with ethidium bromide and the plasmid topological forms (bands) were visualized. The results revealed that hiperico extract is neither capable of altering the survival of E. coli cells nor the plasmid DNA topology but it may have protected these cells against the SnCl2 action. The data suggest absence of cytotoxic and genotoxic effects of the aqueous hiperico extract and a protective effect on E. coli cells against the action of SnCl2.

Hipérico (Hypericum perforatum or St John's worth) tem sido usado como uma planta medicinal para tratar a depressão. Hipericina é o principal componente do hipérico. O cloreto estanoso (SnCl2) é o agente redutor mais utilizado em medicina nuclear. O objetivo desse trabalho foi verificar o efeito de um extrato de hipérico na sobrevivência de Escherichia coli AB1157 e na topologia do DNA plasmidial. Culturas de E. coli AB1157, em fase exponencial, foram incubadas com SnCl2 na presença ou ausência de hipericina. Alíquotas foram espalhadas em placas de Petri contendo meio sólido, as unidades formadoras de colônias foram contadas após incubação e as frações de sobrevivência calculadas. DNA plasmidial foi incubado com SnCl2 na presença ou ausência de hipericina durante 40 minutos, eletroforese em gel de agarose a 0,8 por cento foi realizada, o gel foi corado com brometo de etídio e as formas (bandas) topológicas do plasmídeo visualizadas. Os resultados revelaram que o extrato de hipérico não foi capaz de alterar a sobrevivência da cultura de E. coli e a topologia do DNA plasmidial, mas protegeu as bactérias contra a ação do SnCl2. Os resultados sugerem ausência de efeitos citotóxicos e genotóxicos do extrato aquoso do hipérico e um efeito protetor nas células de E. coli contra a ação do SnCl2.

Low productivity of ribonucleotide reductase in Saccharomyces cerevisiae increases sensitivity to stannous chloride

Ribonucleotide reductase (RNR) of the yeast Saccharomyces cerevisiae is a tetrameric protein complex, consisting of two large and two small subunits. The small subunits Y2 and Y4 form a heterodimer and are encoded by yeast genes RNR2 and RNR4, respectively. Loss of Y4 in yeast mutant rnr4delta can be compensated for by up-regulated expression of Y2, and the formation of a small subunit Y2Y2 homodimer that allows for a partially functional RNR. However, rnr4delta mutants exhibit slower growth than wild-type (WT) cells and are sensitive to many mutagens, amongst them UVC and photo-activated mono- and bi-functional psoralens. Cells of the haploid rnr4delta mutant also show a 3- to 4-fold higher sensitivity to the oxidative stress-inducing chemical stannous chloride than those of the isogenic WT. Both strains acquired increased resistance to SnCl2 with age of culture, i.e., 24-h cultures were more sensitive than cells grown for 2, 3, 4, and 5 days in liquid culture. However, the sensitivity factor of three to four (WT/mutant) did not change significantly. Cultures of the rnr4delta mutant in stationary phase of growth always showed higher frequency of budding cells (budding index around 0.5) than those of the corresponding WT (budding index <0.1), pointing to a delay of mitosis/cytokinesis.

The male reproductive system and the effect of an extract of a medicinal plant (Hypericum perforatum) on the labeling process of blood constituents with technetium-99m

Hypericum perforatum (hiperico) is a plant that has been used to treat diseases and also inhibits rat and human vas deferens contractility. In nuclear medicine, stannous chloride (SnCl2) is used as a reducing agent to obtain radiopharmaceuticals labeling with technetium-99m. As the SnCl2 seems to have adverse effects related with the reproductive performance of male rabbits as well as the human consumption of hiperico might affect sexual function. In the present work, consistent results show significant changes on the blood constituents labeled by technetium-99m obtained from young rats under the effect of an hiperico extract as opposed to blood samples equally treated taken from elderly rat.. Supposedly, this extract could protect the male reproductive system against action of SnCl2 at least in young rats. The findings described in this work allow introducing a simple assay to evaluate the action of products that could interfere with the male reproductive system.

Hypericum perforatum (hiperico) tem sido utilizado para tratar diferentes distúrbios e também inibir a contractilidade do ducto deferente em ratos e em humanos. Na medicina nuclear, o cloreto estanoso (SnCl2) é usado como um agente redutor para obter radiofármacos marcados com tecnécio-99m. Como o SnCl2 parece acarretar efeitos indesejáveis relacionados com o desempenho reprodutivo de coelhos machos e o hiperico pode afetar a função sexual em humanos, o objetivo desse trabalho é apresentar resultados sobre o efeito de um extrato de hiperico na marcação de constituintes sangüíneos com o tecnécio-99m retirados de ratos jovens e idosos. O hiperico parece alterar a marcação de constituintes sangüíneos com tecnécio-99m isolados de sangue de animais jovens. Embora, esse resultado não seja observado em ratos idosos. Provavelmente, o extrato poderia apresentar uma ação protetora para o sistema reprodutivo contra a ação do SnCl2, pelo menos em ratos jovens. Os resultados descritos nesse trabalho permitem introduzir um ensaio simples para avaliar a ação de produtos que poderiam interferir com o sistema reprodutor masculino.

A Chrysobalanus icaco extract alters the plasmid topology and the effects of stannous chloride on the DNA of plasmids

Chrysobalanus icaco (C. icaco) leaves are used in folk medicine (known as Abajeru in Brazil) to control the glycaemia in diabetic patients. Stannous chloride (SnCl2) is a powerful reducing agent used for different purposes and presents cytotoxic and genotoxic effects. The aim of this work was to investigate the effect of an aqueous C. icaco extract on the plasmid DNA topology and on the effects of the stannous chloride on DNA plasmid. Plasmid pBSK was incubated with a C. icaco extract in the presence or absence of SnCl2 (200 mg/mL), after that, the agarose gel electrophoresis procedure was carried out. Plasmid incubated only SnCl2 was used as positive control and, as negative control, plasmid incubated with Tris buffer. The gels were stained with ethidium bromide, DNA bands were semiquantified by densitometry. The data showed that C. icaco extract alters the electrophoretic profile and decreases significantly (p < 0.05) the effect of SnCl2 on plasmid DNA. The results obtained in this work could indicate a dose-dependent protective action and a genotoxic effect of C. icaco extract on plasmid DNA.

Folhas de Chrysobalanus icaco (C. icaco) são usadas na medicina popular (conhecido como Abajeru no Brasil) para controlar a glicemia em pacientes diabéticos. Cloreto estanoso (SnCl2) é um agente redutor potente usado para diferentes propostas e apresenta efeitos citotóxico e genotóxico. O objetivo deste trabalho foi investigar os efeitos de um extrato aquoso de C. icaco na topologia de DNA plasmidial e nos efeitos do cloreto estanoso sobre o DNA plasmidial. Plasmídios pBSK foram incubados com um extrato de C. icaco na presença ou ausência do SnCl2 (200 mg/mL), em seguida, o procedimento de eletroforese em gel de agarose foi realizado. Plasmídios incubados somente com SnCl2 foram usados como controle positivo e, como controle negativo, plasmídios incubados com tampão Tris. Os géis foram corados com brometo de etídio e as bandas de DNA foram semiquantificadas por densitometria. Os dados mostraram que o extrato de C. icaco altera o perfil eletroforético e diminui significativamente (p < 0,05) os efeitos do SnCl2 sobre DNA plasmidial. Os resultados obtidos neste trabalho indicam uma ação protetora dependente da dose e um efeito genotóxico de extrato de C. icaco sobre o DNA plasmidial.

The effect of glucantime™ on the labeling of blood constituents with technetium-99m

PURPOSE: The labeling of red blood cells (C) with 99mTc is employed in clinical nuclear medicine for a variety of diagnostic procedures. Drugs can alter this labeling method and modify the disposition of the radiopharmaceuticals. In this paper, the influence of glucantime on the labeling of blood constituents with 99mTc was reported. METHODS: Blood was withdrawn from rats and incubated with glucantime. Stannous chloride and 99mTc were added. After centrifugation, plasma (P) and (C) were isolated. Samples of P and C were precipitated with TCA 5%, centrifuged and insoluble (IF) and soluble fractions (SF) separated. The percentages of total activity injected (%ATI) in C, IF-P and IF-C were calculated (p 0.05). RESULTS: The %ATI on C decreased from control to following concentrations of glucantime (6.25%;12.5%;25%;50%;100%), respectively: 94.06±1.29 (control) to 77.15±2.79; to 76.68±1.88; to 75.15±2.79; to 72.64±4.40 and to 63.05±3.84. On IF-C the %ATI decreased from control to all the concentrations of glucantime (3.125%;6.25%;12.5%;25%;50%; 100%), respectively: 93.34±1.18 (control) to 78.81±2.76; to 74.76±4.82; to 74.02±5.32; to 64.35±4.82; to 62.81±1.97 and to 54.55±3.58. CONCLUSIONS: This effect was probably due to products present in this drug that may complex with ions (Sn+2 and 99mTcO-4) or have a direct or indirect effect on intracellular stannous ion concentration.

OBJETIVO: A marcação de hemácias sangüíneas (C) com 99mTc é muito utilizada nos procedimentos diagnósticos na medicina nuclear. Drogas podem alterar este método de marcação e modificar a biodisponibilidade de radiofármacos. Neste trabalho, foi avaliada a influência de glucantime na marcação de elementos sangüíneos com 99mTc. MÉTODOS: Sangue foi retirado de ratos e incubado com glucantime. Adicionou-se cloreto estanoso e 99mTc. Após centrifugação, plasma (P) e (C) foram isolados. Amostras de P e C foram precipitadas com TCA 5%, centrifugadas e separadas em frações solúveis (FS) e insolúveis (FI). Os percentuais de atividade total injetada (%ATI) em C, FI-P e FI-C foram calculados (p 0,05). RESULTADOS: O %ATI em C diminuiu, em relação ao controle, nas seguintes concentrações de glucantime (6,25%;12,5%;25%;50%;100%), respectivamente: 94,06±1,29 (controle) para 77,15±2,79; para 76,68±1,88; para 75,15±2,79; para 72,64±4,40 e para 63,05±3,84. Em FI-C, o %ATI diminuiu, em relação ao controle, em todas as concentrações de glucantime (3,125%;6,25%;12,5%;25%;50%; 100%), respectivamente: 93,34±1,18 (controle) para 78,81±2,76; para 74,76±4,82; para 74,02±5,32; para 64,35±4,82; para 62,81±1,97 e para 54,55±3,58. CONCLUSÕES: Este efeito provavelmente foi devido a produtos presentes nesta droga que podem se complexar com íons (Sn+2 e 99mTcO-4) ou ter um efeito direto ou indireto na concentração intracelular do íon estanoso.