Activity of arginine-phenylalanine and arginine-tryptophan-based surfactants against Staphylococcus aureus.

Aims: This study aimed to evaluate the antibacterial effect of two new cationic surfactants based on phenylalanine-arginine (LPAM) and tryptophan-arginine (LTAM). Materials & methods: Antibacterial activity, mechanism of action and interactions with Staphylococcus aureus enzymes were measured through microbiological, flow cytometry and molecular docking assays, respectively. Results & conclusion: These compounds showed antibacterial activity in the range of 4.06-16.24 µg/ml against planktonic cells and no activity against mature biofilms, since they caused a loss of membrane integrity and increased DNA damage, as revealed by flow cytometry analysis. In silico assays revealed the existence of molecular bonds such as hydrogen bonds, mainly with DNA. Therefore, these compounds have promising pharmacological activity against MRSA strains.

Physicochemical properties and penetration into dentinal tubules of calcium hypochlorite with surfactants

Abstract The aim was to assess the physicochemical properties and the penetration into dentinal tubules of calcium hypochlorite solution [Ca(OCl)2], with or without surfactants. The surfactants benzalkonium chloride, cetrimide, Tween 80 and Triton X-100 were mixed at different concentrations with sodium hypochlorite solution (NaOCl), Ca(OCl)2 and distilled water (control). Once the critical micellar concentration (CMC) of the surfactants in Ca(OCl)2 and NaOCl was determined, pH, free chlorine, surface tension and free calcium ions were evaluated. The penetration into dentinal tubules of NaOCl and Ca(OCl)2, with or without benzalkonium chloride and Triton X-100 [surfactants that promoted the lowest surface tension of Ca(OCl)2], was assessed using human premolars stained with crystal violet. The statistical tests were one-way ANOVA and Tukey's post-test, Kruskal-Wallis and Dunn's post-test, two-way ANOVA and Bonferroni's post-test, and t-test; depending on the assay. The addition of surfactants reduced the surface tension of NaOCl and Ca(OCl)2, and did not alter the pH or the free available chlorine of either solution. The addition of all surfactants increased the availability of free calcium ions in Ca(OCl)2, especially benzalkonium chloride. Ca(OCl)2 exhibited lower penetration into dentinal tubules than NaOCl, and the addition of surfactants did not improve the penetration of Ca(OCl)2, but did increase the penetration of NaOCl. It can be concluded that the addition of surfactants to Ca(OCl)2 did not increase the penetration into dentinal tubules, but it did promote lower surface tension, without changing the pH or free available chlorine values, and higher availability of free calcium ions in Ca(OCl)2.

Resumo O objetivo foi avaliar as propriedades físico-químicas e a penetrabilidade nos túbulos dentinários da solução de hipoclorito de cálcio [Ca(OCl)2], com ou sem surfactantes. Os surfactantes cloreto de benzalcônio, cetrimida, Tween 80 e Triton X-100 foram misturados em diferentes concentrações com a solução de hipoclorito de sódio (NaOCl), Ca(OCl)2 e água destilada (controle). Uma vez determinada a concentração micelar crítica (CMC) dos surfactantes em Ca(OCl)2 e NaOCl, foram avaliados o pH, cloro livre, tensão superficial e íons de cálcio livre. A penetrabilidade nos túbulos dentinários de NaOCl e Ca(OCl)2, com ou sem cloreto de benzalcônio e Triton X-100 [surfactantes que promoveram a menor tensão superficial de [Ca(OCl)2] foi avaliada utilizando pré-molares humanos corados com cristal violeta. Os testes estatísticos foram ANOVA de uma via e pós-teste de Tukey, Kruskal-Wallis e pós-teste de Dunn, ANOVA de duas vias e pós-teste de Bonferroni, e teste t; dependendo do ensaio. A adição de surfactantes reduziu a tensão superficial do NaOCl e Ca(OCl)2, e não alterou o pH ou cloro livre das soluções. A adição de todos os surfactantes aumentou a disponibilidade de íons de cálcio livre de Ca(OCl)2, principalmente o cloreto de benzalcônio. Ca(OCl)2 apresentou menor penetrabilidade nos túbulos dentinários do que NaOCl, e a adição de surfactantes não aumentou a penetrabilidade de Ca(OCl)2, mas aumentou a penetrabilidade de NaOCl. Pode-se concluir que a adição de surfactantes no Ca(OCl)2 não aumentou a penetrabilidade nos túbulos dentinários, mas promoveu menor tensão superficial, sem alterar os valores de pH ou cloro livre, e maior disponibilidade de íons de cálcio livre em Ca(OCl)2.

Arginine-phenylalanine and arginine-tryptophan-based surfactants as new biocompatible antifungal agents and their synergistic effect with Amphotericin B against fluconazole-resistant Candida strains.

In the past two decades, the increase in microbial resistance to conventional antimicrobials has spurred scientists around the world to search tirelessly for new treatments. Synthetic amino acid-based surfactants constitute a promising alternative to conventional antimicrobial compounds. In this work, two new cationic amino acid-based surfactants were synthesized and their physicochemical, antifungal and antibiofilm properties evaluated. The surfactants were based on phenylalanine-arginine (LPAM) and tryptophan-arginine (LTAM) and prepared from renewable raw materials using a simple chemical procedure. The critical micelle concentrations of the new surfactants were determined by conductivity and fluorescence. Micellization of LPAM and LTAM took place at 1.05 and 0.54 mM, respectively. Both exhibited good antifungal activity against fluconazole-resistant Candida spp. strains, with a low minimum inhibitory concentration (8.2 µg/mL). Their mechanism of action involves alterations in cell membrane permeability and mitochondrial damage, leading to death by apoptosis. Furthermore, when LPAM and LTAM were applied with Amphotericin B, a significant synergistic effect was observed against all the studied Candida strains. These new cationic surfactants are also able to disperse biofilms of Candida spp. at low concentrations. The results indicate that LPAM and LTAM have potential application to combat the advance of fungal resistance as well as microbial biofilms.

Physicochemical properties, cytotoxicity and penetration into dentinal tubules of sodium hypochlorite with and without surfactants.

OBJECTIVES: The aim of this study was to assess the physicochemical properties, cytotoxicity and penetration into dentinal tubules of ChlorCid™ Surf (3% sodium hypochlorite [NaOCl] with surfactant) in comparison to ChlorCid™ (3% NaOCl without surfactant). MATERIALS AND METHODS: The physicochemical properties evaluated were pH, surface tension, free available chlorine (FAC) and contact angle. Cytotoxicity was evaluated in L929 fibroblasts exposed to the solutions by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide and neutral red assays. Assessment of penetration into dentinal tubules was performed by staining single-rooted permanent human teeth with crystal violet (n = 9), which were irrigated with the solutions and analyzed in cervical, middle and apical segments. Data were analyzed by one-way analysis of variance (ANOVA) and Tukey's post-test, 2-way ANOVA and Bonferroni's post-test or t-test (α = 0.05). RESULTS: ChlorCid™ Surf and ChlorCid™ FAC values were close to those indicated by the manufacturer. ChlorCid™ Surf showed lower surface tension and contact angle on dentin, and higher pH than ChlorCid™ (p < 0.05). The penetration of ChlorCid™ Surf was higher in cervical and middle segments, compared with ChlorCid™ (p < 0.05). There was no difference in irrigant cytotoxicity (p > 0.05). CONCLUSIONS: ChlorCid™ Surf showed lower surface tension, lower contact angle on root canal dentin, higher penetration into dentinal tubules and more alkaline pH, compared with ChlorCid™. However, both solutions showed similar cytotoxicity and FAC content.

Penetration of sodium hypochlorite into root canal dentine: effect of surfactants, gel form and passive ultrasonic irrigation.

AIM: To assess the penetration of sodium hypochlorite (NaOCl) gel or NaOCl solutions with surfactants, and the effect of passive ultrasonic irrigation (PUI) on penetration into dentinal tubules. METHODOLOGY: Bovine incisor root canals were instrumented, the roots sectioned and the dentine blocks obtained were stained with crystal violet. Dentine blocks (n = 10 per group) were exposed to 3% NaOCl gel or 3% NaOCl solution for 10 and 20 min. Other dentine blocks (n = 10 per group) were exposed to Chlor-Extra (6% NaOCl + surfactant), 6% NaOCl, 2.5% NaOCl with 0.2% cetrimide and 2.5% NaOCl for 10 and 20 min. The penetration depth of irrigants into dentinal tubules was measured in micrometres by viewing the bleached crystal violet under a stereomicroscope. Additionally, bovine incisor root canals, instrumented and stained with crystal violet, were distributed into two groups (n = 10) and irrigated with 2.5% NaOCl with PUI or conventional syringe irrigation (CSI). The penetration depth of irrigants into dentinal tubules was assessed 3 and 7 mm from the apex. Statistical analysis was performed by ANOVA and Tukey tests (α = 0.05). RESULTS: There was significantly greater penetration of 3% NaOCl solution into dentinal tubules compared with the gel form (P < 0.05). There was no difference (P > 0.05) between 6% NaOCl and Chlor-Extra, and between 2.5% NaOCl and 2.5% NaOCl + cetrimide. PUI significantly increased the penetration depth of NaOCl into dentinal tubules when compared with CSI (P < 0.05). CONCLUSIONS: In extracted bovine incisors, NaOCl gel penetrated less into dentinal tubules than NaOCl solution. The addition of surfactants did not increase the penetration depth. The use of PUI significantly increased NaOCl penetration into dentinal tubules.

Desenvolvimento e caracterização de formulação de hipoclorito de sódio em gel para uso endodôntico / Development and characterization of sodium hypochlorite gel formulation for endodontic use

A presente pesquisa dedicou-se ao desenvolvimento e à caracterização de uma formulação em gel para o NaOCl, que permitisse o maior controle dessa substância durante a irrigação do sistema de canais radiculares sem perder as características que o tornam um agente de limpeza e descontaminação tão eficiente. Foi utilizada uma solução concentrada de NaOCl, a qual foi titulada para determinação do teor de cloro ativo, e um tensoativo, o lauril éter sulfato de sódio, para o qual foi calculada a concentração micelar crítica em água destilada. A partir destes reagentes foram realizadas diluições e manipuladas sete formulações de NaOCl a 2,5% com diferentes concentrações do tensoativo, as quais foram submetidas às análises de pH, tensão superficial, espectroscopia de infravermelho com transformada de Fourier (FTIR), molhabilidade em dentina humana, reologia, potencial antibacteriano contra Enterococcus faecalis e capacidade de dissolução tecidual. Os valores de pH demonstraram que a adição do tensoativo não alterou este parâmetro, mantendo o meio alcalino desejável para a ação do NaOCl. A adição do tensoativo reduziu a tensão superficial em mais de 50% em relação à solução aquosa de NaOCl. A caracterização por FTIR demonstrou que os reagentes das formulações apenas se solubilizam e interagem, não implicando a ocorrência de reação química entre elas. A molhabilidade das formulações sobre a dentina humana foi inferior à medida para a solução de NaOCl. Todas as formulações apresentaram viscosidade e aspecto que permitem a utilização clínica de forma satisfatória. O teste microbiológico de disco-difusão em ágar revelou ação satisfatória e similar à solução aquosa de NaOCl 2,5%. A velocidade de dissolução tecidual foi reduzida pela adição do tensoativo. Concluiu-se que as formulações de NaOCl em gel com o lauril éter sulfato de sódio são promissoras para sua utilização como substâncias químicas auxiliares em Endodontia (AU).

This research focused on the development and characterization of a gel formulation for NaOCl, which allows greater control during the root canals irrigation without losing the characteristics that make it such na efficient cleaning and decontamination agent. It was used a concentrated solution of NaOCl, which was titrated to determine the active chlorine content, and a surfactant, sodium lauryl ether sulfate, for which the critical micellar concentration in distilled water was calculated. From these reagents were carried out dilutions and manipulated seven formulations of 2.5% NaOCl with different surfactant concentrations, which were submitted to the following analysis: pH, surface tension, Fourier transform infrared spectroscopy (FTIR), wettability on human dentin, rheology and antibacterial potential against Enterococcus faecalis. The pH values showed that the addition of the surfactant did not alter this parameter, keeping the alkaline medium desirable for NaOCl action. The surfactant addition reduced surface tension by more than 50% relative to the NaOCl aqueous solution. The FTIR showed that the reagents only solubilize and interact, not implying the occurrence of chemical reaction between them. The wettability on human dentin was lower than that measured for the NaOCl solution. All formulations showed viscosity and appearance that allow clinical use satisfactorily. The microbiological disk-diffusion test on agar showed a satisfactory action similar to the 2.5% aqueous NaOCl solution. The ability of tissue dissolution was reduced by the addition of the surfactant. It was concluded that NaOCl gel formulations with sodium lauryl ether sulfate are promising for their use as endodontic auxiliary chemicals (AU).

Máscara laríngea ProSealTM como via de administração de surfactante no tratamento da síndrome do desconforto respiratório em recém-nascido pré-termo / ProSealTM laryngeal mask airway for surfactant administration in the treatment of respiratory distress syndrome in a premature infant

A administração de surfactante pela cânula traqueal e ventilação mecânica é o tratamento convencional da síndrome do desconforto respiratório em prematuros. Alterações hemodinâmicas e respiratórias da intubação traqueal e pré-medicação justificam a busca por alternativas menos invasivas de administração de surfactante. O objetivo do presente estudo foi descrever o uso da máscara laríngea ProSealTM como opção para o tratamento da síndrome do desconforto respiratório em recém-nascido pré-termo com 31 semanas de gestação, 1.335 g, dificuldade respiratória após a primeira hora de vida, e quadro clínico e radiológico de síndrome do desconforto respiratório. O surfactante foi administrado pela máscara laríngea ProSealTM com 3,5 horas de vida, com boa tolerância e sem necessidade de intubação traqueal. Gasometria normal e melhora radiológica, após 3 e 6 horas. O oxigênio foi suspenso após 8 dias; alta sem comorbidades. A máscara laríngea parece ser alternativa indolor e menos invasiva de via de tratamento da síndrome do desconforto respiratório, com possibilidade de redução de intubação traqueal e ventilação mecânica. Por meio de amostra adequada, devem ser confirmadas a eficácia e as vantagens dessa via de tratamento.

The administration of surfactant via tracheal cannula with mechanical ventilation is the conventional treatment for infant respiratory distress syndrome. Hemodynamic and respiratory changes due to tracheal intubation and the need for premedication justify the search for less invasive alternatives of surfactant administration. The objective of this study was to describe the use of the ProSealTM laryngeal mask airway as an option for the treatment of respiratory distress syndrome in a premature infant born at 31 weeks of gestation, at 1335 g, with respiratory difficulty after the first hour of life and exhibiting the clinical and radiologic features of respiratory distress syndrome. The surfactant was administered with the use of the ProSealTM laryngeal mask airway at 3.5 hours of life. It was well tolerated, with no need for tracheal intubation. Normal gasometry and radiologic improvement were observed after three and six hours of administration. Oxygen administration was suspended after eight days, with no comorbidities at discharge. The laryngeal mask airway seems to be a painless and less invasive alternative to treat respiratory distress syndrome and may reduce the need for tracheal intubation and mechanical ventilation. The efficacy and advantages of this route of treatment should be confirmed in a study of an adequate sample.

Biocide activity of microfiber mops with and without silver after contamination

OBJECTIVE: The purpose of the present research was to compare the residual microbial load in Solo System microfiber mops with silver and in normal microfiber mops without silver to see whether those with the silver prevent bacterial proliferation and spread more effectively during normal cleaning operations. METHODS: Mops with and without silver were experimentally contaminated with suspension of Staphylococcus aureus ATCC 6538. The bioburden was evaluated by a filtering procedure according to UNI EN 1174 after contamination, after washing and after different times of impregnation in an alcohol-base detergent. RESULTS AND DISCUSSION: The results obtained lead to the conclusion that silver microfiber mop was significantly more effective in reducing bacterial load despite initial high level contamination (10(6)-10(7) CFU/50 cm²). Indeed, after low temperature washing, the bacterial load was already completely eliminated while the mop without silver still presented relatively high levels of the microorganism (approximately 10² CFU/50 cm²) even after being soaked for 8 hours in a detergent/disinfectant.

Ventilação de alta freqüência por oscilação comparada a ventilação mecânica convencional associada a reposição de surfactante em coelhos / High frequency oscillation ventilation compared to conventional mechanical ventilation plus exogenous surfactant replacement in rabbits

Objetivos: a) avaliar o efeito na oxigenação e ventilação de coelhos artificialmente depletados de surfactante quando submetidos à ventilação mecânica convencional associada à reposição parcial de surfactante exógeno; b) comparar a evolução deste grupo com outro grupo submetido à ventilação de alta freqüência por oscilação (HFO) sem reposição associada de surfactante. Métodos: Vinte coelhos brancos da raça New Zealand, peso de + 3 kg, foram anestesiados e artificialmente induzidos à depleção de surfactante endógeno através de sucessivas lavagens pulmonares com alíquotas (25 ml/kg) de solução fisiológica, até atingir uma PaO2 menor que 100 mmHg, quando ventilados via traqueostomia no modo de pressão controlada objetivando um volume corrente de 10ml/kg, com PEEP de 5cm H2O, FiO2 de 100%, freqüência respiratória de 30 mpm, e tempo inspiratório de 0,65 s. Posteriormente, os coelhos foram divididos em (a) grupo CMV+S, submetido à ventilação convencional associada com reposição parcial de surfactante exógeno; (b) grupo HFO submetido à ventilação de alta freqüência por oscilação. Gasometrias arteriais foram coletadas antes da lavagem pulmonar, após a lavagem pulmonar, 15, 60 e 120 minutos após iniciado o tratamento. Os grupos foram comparados utilizando-se o teste t de Student. Resultados: Em ambos grupos a PaO2 (pós lavagem pulmonar) era inferior a 50mmHg (p=0,154), subindo aos15 minutos de tratamento para 254 mmHg (CMV+S) e 288 mmHg (HFO, p=0,626). Aos 60 e 120 minutos, a PaO2 foi maior (p=0,001) no grupo HFO (431 e 431 mmHg) quando comparado com o grupo CMV+S, que apresentou queda progressiva (148 e 126 mmHg). Aos 60 minutos a PaCO2 era significativamente menor no grupo do CMV+S (29 versus 41 mmHg). Conclusões: Em modelo animal com SARA a estratégia de ventilação protetora como a HFO, isoladamente, promove uma rápida e persistente melhora na oxigenação, inclusive, com níveis superiores aos obtidos pelos animais submetidos à ventilação mecânica convencional associada à reposição de surfactante.

Objectives: (a) to evaluate the effect on oxygenation and ventilation of rabbits with induced surfactant depletion when they are submitted to a conventional mechanical ventilation, plus a small dose of exogenous surfactant; (b) to compare this group with another group submitted to a High Frequency Oscillation (HFO) without exogenous surfactant administration. Methods: Twenty New Zealand White rabbits weighing (+ 3 kg) were anaesthetized and artificially induced to a endogenous surfactant depletion by successively lung lavage with normal saline (aliquots of 25 ml/kg) until to reach a persistent PaO2 less than 100 mmHg when submitted to a mechanical ventilation in a pressure control mode with a target tidal volume of 10ml/kg, PEEP of 5cm H2O, FiO2 1.0, respiratory rate 30/min, and inspiratory time of 0.65 s. Then the rabbits were divided in (a) CMV+S group, submitted to a conventional mechanical ventilation plus exogenous surfactant replacement; (b) HFO group, submitted to a High Frequency Oscillation Ventilation. Arterial blood gases were measured at control period, post lung lavage, 15, 16 and 120 minutes after treatment started. The groups were compared using Student t test. Results: The post lung lavage PaO2 in both groups was lower than 50mmHg (p=0.154), increasing after 15 min of treatment to 254 mmHg (CMV+S) and 288 mmHg (HFO, p=0.626). The PaO2 at 60 and 120 minutes were higher (p=0.001) in the HFO group (431 e 431 mmHg) when compared with the CMV+S group, which showed a progressive fall (148 e 126 mmHg). At 60 minutes of treatment, the PaCO2 was lower (p=0.008) in the CMV+S group (29 versus 41 mmHg). Conclusions: In ARDS animal model a protect mechanical ventilation strategy as HFO by itself promotes a fast and persistent increase in the oxygenation, with superior levels than those observed in animals treated with conventional mechanical ventilation plus exogenous surfactant replacement.