Cytotoxicity evaluation, antibacterial effect, and degree of conversion of QAM-containing adhesives

Abstract The aim of this study was to evaluate the influence of adding quaternary ammonium methacrylates (QAMs) to experimental adhesives by assessing the degree of conversion (DC), cytotoxicity against keratinocytes and fibroblasts, and antibacterial activity against biofilm formation. Two QAMs were added to an experimental adhesive: dimethylaminododecyl methacrylate bromododecane (DMADDM) or dimethylaminododecyl methacrylate bromohexadecane (DMAHDM) at three concentrations each: 1, 2.5, and 5 wt.%. Experimental adhesive without QAMs (control group) and commercially available Transbond XT Primer (3M Unitek, Monrovia, California, USA) were used for comparisons. The adhesives were tested for DC, cytotoxicity against keratinocytes and fibroblasts, and antibacterial activity against biofilm formation. DC, cytotoxicity against fibroblasts, and antibacterial activity were analyzed using one-way ANOVA and Tukey's multiple comparisons. Cytotoxicity against keratinocytes was evaluated using the Kruskal Wallis and Dunn's post-hoc (α = 5%) tests. Transbond showed lower DC as compared to 5% DMAHDM, 1% DMADDM, and 5% DMADDM (p < 0.05). However, all groups presented proper DC when compared to commercial adhesives in the literature. In the evaluation of cytotoxicity against keratinocytes, Transbond induced higher viability than 2.5 wt.% groups (p < 0.05). Against fibroblasts, Transbond induced higher viability as compared to 5 wt.% groups (p < 0.05). DMAHDM at 5 wt.% reduced biofilm formation when compared to all the other groups (p < 0.05). Despite their cytotoxic effect against keratinocytes, gingival fibroblasts showed higher viability. DMAHDM at 5 wt.% decreased Streptococcus mutans viability. The incorporation of DMAHDM at 5 wt.% may be a strategy for reducing the development of white spot lesions.

Research progress on root canal irrigation disinfection drugs / 口腔疾病防治

@#Endodontic infection control is crucial to successful root canal treatment. Irrigation is the key step in endodontic procedures, and the application of root canal irrigation and disinfection medications play an important role. How to enhance antibacterial effects and functions in removing tissues while maintaining biocompatibility is a hot topic in endodontics. Currently, insights to address this issue can be split into two categories: one, the modification or combination of conventional endodontic irrigation solutions, and two, the development of novel endodontic irrigation solutions with new technologies and materials, for instance, nanomaterials and natural exacts. However, conventional endodontic irrigation solutions, such as sodium hypochlorite and chlorhexidine, are still the first choice in clinical practice. Most novel endodontic irrigation solutions remain at the pre-clinical laboratory stage. Clinical research and relevant data are required to determine whether various methods can improve endodontic irrigation. From basic research to clinical application is the direction for advancing to the next stage. The present article focuses on research progress on endodontic irrigation, especially concerning its antibacterial mechanism, characteristics and efficacy, to provide a reference for future clinical translation.

Research progress of bacterial biofilm eradication agents based on modifications of natural products / 药学学报

Bacterial biofilm widely exists in all kinds of bacteria, and is related to about 80 percent of bacterial infections. It is one of the main reasons for bacterial tolerance and resistance to existing antibiotics. Therefore, there is unmet clinical need for new anti-biofilm drugs. At present, there are three kinds of anti-biofilm agents under research, including biofilm inhibitors, biofilm dispersal agents and biofilm eradication agents. Among them, the biofilm eradication agent is unique, which can not only kill bacteria in biofilm but also eliminate biofilm as a monotherapy. Based on modifications of natural products with antibacterial activity, a variety of compounds with biofilm eradicating activities have been obtained, such as, acyldepsipeptides, pyrrolomycins, halogenated phenazines and halogenated 8-hydroxyquinolines. In this review, we summarize several major biofilm eradication agents above according to their structures and mechanisms.

Evaluation of current disinfection practice of transvaginal ultrasound probes in a Philippine Tertiary Referral Hospital: A comparative study on the performance of manual reprocessing methods

Objectives@#There are no standard infection control regulations in transvaginal ultrasound probe disinfection followed in the most prominent local public tertiary referral hospital. Likewise, no studies have evaluated the efficacy of the current method that uses an inexpensive multipurpose antiseptic spray solution. This study aims to evaluate the efficacy of the current practice of manual disinfection of TVS probes and compare it with the performance of an acceptable manual reprocessing method. @*Methods@#A prospective, randomized, controlled study was carried out using a crossover, quasi-experimental design, collecting 119 total samples from the ultrasound transducers before (35 samples) and after disinfection with two manual reprocessing methods, either a locally manufactured multipurpose antiseptic spray (A-Septic® Multipurpose Antiseptic Spray) that is currently used for disinfection or Mikrozid Sensitive®, a ready to use impregnated wipes (42 samples each arm). Disinfection efficacy was evaluated based on microbial culture results. @*Results@#Before disinfection, bacterial growth was observed in 77.1% (27/35) of the probes. After disinfection, 80.95% (34/42) remained contaminated with the antiseptic spray and 21.43% (9/42) with the wipes. The cultures revealed many environmental and pathogenic bacterial isolates, including Burkholderia, Staphylococcus, Acinetobacter, Diphtheroids, and Pseudomonas. @*Conclusions@#The currently used method for disinfecting transvaginal transducers in the division is not adequate for decontamination and decreasing the risk of cross contamination among patients. The results call for aggressive disinfection measures and highlight the need to update local standards and formulate and institutionalize these recommendations.

Resistencia antimicrobiana y daño al medio ambiente, en el contexto COVID-19: Una revisión sistemática / Antimicrobial resistance and damage to the environment, in the context of COVID-19: A systematic review

Las pautas de abordaje de los pacientes con COVID-19, al inicio de la pandemia, se realizó por ensayo, ya que se desconocía la fisiopatología de esta nueva enfermedad, entre las acciones médicas se describió el uso de antiboticoterapias de manera indiscriminada, también se instó a realizar desinfección profundas, muchas veces, con sustancias químicas con impacto negativo en la salud ambiental, tanto a nivel de la microbiota encargada del equilibrio ecológico, como en la contaminación ambiental, principalmente del agua. Aunado a esto, debido a la emergencia sanitaria, se requirió usar en mayor cantidad equipos de protección personal de un solo uso y, como consecuencias el aumento de desechos sólidos peligrosos, cuya composición son de degradación tardía. Por tanto, la respuesta sanitaria ante la pandemia, probablemente fue escenario para acentuar la resistencia antimicrobiana y el riesgo de daño ambiental. En este, artículo se realizó una revisión sistemática de la literatura científicas en torno a estos tópicos, las evidencias demostraron el aumento de mecanismos de resistencias de bacterias, principalmente, patógenas del tracto respiratorio. De igual manera, el impacto negativo por uso irracional de desinfectantes químicos, traducido en bacterias resistentes especialmente a compuestos de amonio cuaternario. La bioacumulación y biomagnificación de estas sustancias ha provocado toxicidad, mutaciones, propagación de genes de resistencia. Por lo tanto, se sugiere que se priorice las estrategias que mitiguen el rastro que ha venido extendiéndose al paso de la pandemia por el SAR- CoV-2(AU)

The guidelines for the approach of patients with COVID-19, at the beginning of the pandemic, were carried out by trial, since the pathophysiology of this new disease was unknown, among the medical actions the use of antibiotic therapies indiscriminately was described, also the urged to carry out deep disinfection, many times, with chemical substances with a negative impact on environmental health, both at the level of the microbiota responsible for the ecological balance, and in environmental pollution, mainly of water. In addition to this, due to the health emergency, it was required to use more single-use personal protective equipment and, as a consequence, the increase in hazardous solid waste, whose composition is delayed degradation. Therefore, the health response to the pandemic was probably the setting to accentuate antimicrobial resistance and the risk of environmental damage. In this article, a systematic review of the scientific literature on these topics was carried out, the evidence demostrated the increase in resistance mechanisms of bacteria, mainly pathogens of the respiratory tract. Anyways, the negative impact due to the irrational use of chemical disinfectants, translated into resistant bacteria, especially to quaternary ammonium compounds. The bioaccumulation and biomagnification of these substances has caused toxicity, mutations, propagation of resistance genes. Therefore, it is suggested that strategies be prioritized that mitigate the trail that has been spreading as the pandemic passed by SAR-CoV-2(AU)

Action of benzalkonium chloride in different pH

Ammonium quaternary compounds are widely used in poultry and swine production as disinfectants in the control of pathogens. They act on gram-positive bacteria, gram-negative bacteria, enveloped fungi and viruses. However, in some conditions of pH and presence of organic matter can be inactivated. This study evaluated the action of ammonium quaternary compounds at 1:1,000 and 1:2,000 dilutions against Salmonella enterica serovarTyphimurium and Salmonella enterica serovar Enteritidis in the presence of three different organic matter simulators, fetal bovine serum, skim milk and whole milk concentration of 1, 3, 5, and 7% and at pH 6 and 9, with 15 min of contact. It was possible to verify that the organic matter simulators adjusted in the same conditions of contact time and percentage, in the in vitro tests, presented different results and the fetal bovine serum did not inactivate the disinfectant. However, the best result against S. Typhimurium and S. Enteritidis was obtained at pH 6 at the dilution of 1:1,000 in all organic matter simulators.

Physicochemical properties and biological effects of quaternary ammonium methacrylates in an experimental adhesive resin for bonding orthodontic brackets

Abstract Fixed orthodontic appliances may lead to biofilm accumulation around them that may increase caries risk. This study aimed to evaluate the influence of quaternary ammonium methacrylates (QAMs) on the physicochemical properties, cytotoxicity, and antibacterial activity of adhesive resins for orthodontic purposes. Methodology: A base resin was prepared with a comonomer blend and photoinitiator/co-initiator system. Two different QAMs were added to the base adhesive: dimethylaminododecyl methacrylate at 5 wt.% (DMADDM) or dimethylaminohexadecyl methacrylate (DMAHDM) at 10 wt.%. The base adhesive, without QAMs, (GC) and the commercial Transbond™ XT Primer 3M (GT) were used as control. The resins were tested immediately and after six months of aging in the water regarding the antibacterial activity and shear bond strength (SBS). The antibacterial activity was tested against Streptococcus mutans via metabolic activity assay (MTT test). The groups were also tested for the degree of conversion (DC) and cytotoxicity against keratinocytes. Results: The resins containing QAM showed antibacterial activity compared to the commercial material by immediately reducing the metabolic activity by about 60%. However, the antibacterial activity decreased after aging (p<0.05). None of the groups presented any differences for SBS (p>0.05) and DC (p>0.05). The incorporation of DMADDM and DMAHDM significantly reduced the keratinocyte viability compared to the GT and GC groups (p<0.05). Conclusion: Both adhesives with QAMs showed a significant reduction in bacterial metabolic activity, but this effect decreased after water aging. Lower cell viability was observed for the group with the longer alkyl chain-QAM, without significant differences for the bonding ability and degree of conversion. The addition of QAMs in adhesives may affect the keratinocytes viability, and the aging effects maybe decrease the bacterial activity of QAM-doped materials.

Good cell compatibility and permeability of silk fibroin/chitosan composite scaffolds / 中国组织工程研究

BACKGROUND: Silk fibroin and chitosan are commonly used as scaffolds In tissue engineering, but there are some shortcomings In their separate application. When they are mixed, they can be modified each other. They give full play to each other’s advantages and become Ideal composite scaffolds. OBJECTIVE: To prepare Silk fibroin/chitosan composite scaffold and determineits properties. METHODS: The silk fibroin/chitosan composite scaffolds were prepared by freeze-drying method. The morphology and structure of the composite scaffolds were examined by scanning electron microscopy. The properties of the composite scaffolds were tested by thermogravlmetric analysis, mechanical properties test, and cytotoxicity test. The quaternion chitosan was prepared. The nuclear magnetic resonance spectrum was detected by nuclear magnetic resonance instrument. The potential and particle size distribution were detected by Zeta potentiometer. The protection of DNA was detected by gel electrophoresis. The binding with DNA was observed by transmission electron microscope. RESULTS AND CONCLUSION: (1 ) The results of scanning electron microscopy showed that the silk fibroin/chitosan composite scaffolds had a good three-dimensional pore structure, with a pore size of 50-100 urn. (2) The results of thermogravimetric analysis showed that when the temperature was less than 200 °C, the mass loss rate of silk fibroin/chitosan composite scaffold was lower. When the temperature Increased to 200-500 °C, the mass loss rate of the scaffold began to accelerate, and the loss amount increased. At 800 °C, the residual mass of the composite scaffold was 38%. (3) The maximum strain of silk fibroin/chitosan composite scaffold reached 94.94%, and the maximum stress was 7.01 MPa. (4) The results of CCK-8 experiment showed that silk fibroin/chitosan composite scaffolds had no cytotoxicity to rabbit bone marrow mesenchymal stem cells and had good cell compatibility. (5) The results of nuclear magnetic resonance spectra showed that the quaternion degree of quaternary ammonium chitosan was about 20%. (6) The particle size distribution of quaternized chitosan was (588.56±52.39) nm, and the surface of quaternized chitosan was positively charged with a potential of (16.3±3.92) mV, which was beneficial to the combination with DNA. (7) The results of gel electrophoresis experiments showed that the higher the proportion of quaternion chitosan, the better the encapsulation of DNA. When the ratio of chitosan/DNA was 1 : 3, the encapsulation effect was achieved. (8) The results of transmission electron microscopy showed that most of the particles of quaternized chitosan/DNA were solid and round; the particle size difference was small; and the average particle size was about 200 nm. (9) The results showed that silk fibroin/chitosan composite scaffolds had a good biocompatibility and cell permeability, which was conducive to the growth of cells between scaffolds.

Resistência aos compostos de amônio quaternário (QACs) de uso doméstico e hospitalar em patógenos prioritários multirresistentes / Resistance to quaternary ammonium compounds (QACs) for domestic and hospital use in multiresistant priority pathogens

Compostos de amônio quaternário (QACs) têm sido amplamente utilizados como desinfetantes e antissépticos, sendo essenciais na prevenção e controle de infecções bacterianas na medicina humana e veterinária. Embora patógenos prioritários multirresistentes têm sido muito bem caracterizados quanto ao perfil de suscetibilidade e contexto genético da resistência aos antibióticos, dados de resistência aos QACs são limitados. Assim, o objetivo do presente estudo foi avaliar a atividade in vitro dos QACs de uso doméstico e hospitalar [cloreto de benzalcônio (BAC), cloreto de cetilpiridinio (CPC) e brometo de cetiltrimetilamônio (CTAB)], contra patógenos prioritários multirresistentes, identificando os principais genes de resistência associados. Foram estudadas 100 cepas multirresistentes previamente sequenciados usando as plataformas Illumina MiSeq e NextSeq representativas de diferentes hospedeiros (humanos e animais) e fontes (ambientes e alimentos). As cepas foram identificadas como Klebsiella pneumoniae (n= 24), Escherichia coli (n= 30); Pseudomonas aeruginosa (n= 10), Enterobacter spp, (n= 8), Acinetobacter baumannii (n= 11) e Salmonella spp. (n= 17). Genes de resistência aos QACs foram identificados in silico através do alinhamento dos contigs obtidos de cada cepa sequenciada com genes de referência obtidos do GenBank, utilizando o programa Geneious versão 8 (Biomatters Ltd). A identidade de cada gene foi analisada utilizando o programa BLASTx, no qual um critério baseado em ≥90% identidade resultou na identificação dos genes mdfA (77%), qacE (44%), qacEΔ1 (43%), sugE(c) (29%), emrE (21%), qacA (19%), sugE(p) (5%), qacF (7%), qacH (7%) e qacL (7%) em 85 cepas; enquanto que 15 cepas não possuíam nenhum gene de resistência aos QACs. A concentração inibitória mínima (CIM) dos QACs para as 100 cepas foi determinada pelo método de microdiluição em caldo. Os resultados sugeriram que a resistência em patógenos prioritários circulando na interface humano-ambiente-animal não é restrita aos antibióticos, uma vez que a elevada ocorrência de genes qacE, qacEΔ1 e mdfA poderia estar associada com uma redução da suscetibilidade para QACs. Consequentemente, a resistência aos QACs poderia também contribuir para a persistência e adaptação destes patógenos nos seres humanos e outros animais, assim como em ambientes impactados antropogenicamente

Quaternary ammonium compounds (QACs) have been widely used as disinfectants and antiseptics, being applied as essential compounds in the prevention and control of bacterial infections in human-and veterinary hospital medicine. Although multiresistant priority pathogens have been well characterized with respect to their susceptibility profile and their genetic context of resistance for antibiotics, studies of resistance to QACs are limited. Thus, the objective of the present study was to evaluate the in vitro activity of QACs [(benzalkonium chloride (BAC), cetylpyridinium chloride (CPC) and cetyltrimethylammonium bromide (CTAB)] for household and hospital use against multiresistant priority pathogens, identifying the main resistance genes associated. A hundred multiresistant isolates (previously sequenced using the Illumina MiSeq and NextSeq platforms), representative of different hosts (humans and animals) and sources (environment and food) were studied. Isolates were identified as Klebsiella pneumoniae (n=24), Escherichia coli (n=30), Pseudomonas aeruginosa (n=10), Enterobacter spp. (n=8), Acinetobacter baumannii (n=11) and Salmonella spp. (n=17). In silico analysis for identification of genes conferring resistance to QACs were performed by aligning the contigs obtained from the strains with reference genes deposited in GenBank, using the Geneious version program (Biomatters Ltd). Similarities were analyzed using the BLASTx online program, considering the alignment criteria based on ≥ 90% identity. The result of these analysis revealed the presence of the following QAC genes: mdfA (77%), qacE (44%), qacEΔ1 (43%), sugE(c) (29%), emrE (21%), qacA (19%), sugE (p) (5%), qacF (7%), qacH (7%) e qacL (7%); while 15 strains showed no resistance genes for QACs. Determination of QACs minimum inhibitory concentration (MIC) for the 100 isolates, by the broth microdilution method. These results suggest that resistance to QACs in priority pathogens, circulating at the human-environment-animal interface, is not restricted to antibiotics, since the high occurrence of genes qacE, qacEΔ1 and mdfA were associated with a reduced susceptibility to QACs. Consequently, resistance to QACs could also contribute to the persistence and adaptation of these pathogens in humans and othes animals, as well as in anthropogenically impacted environments

Recent advances in the application of quaternary ammonium compounds in biomedical materials / 口腔疾病防治

@#Microbial infections affect people worldwide. Quaternary ammonium salts serve antibacterial, antifungal, antiviral, anti-matrix metalloproteinase and polymerization functions. While the modification of biomaterials with quaternary ammonium salts cannot affect the physical or chemical properties of the biomaterials, this process can confer them with stable biological activity. Currently, quaternary ammonium salts are widely used in the development of functional orthopedic materials, sutures, dressings and dental materials, and the idea of modifying biomedical materials with quaternary ammonium salts has become the most promising, e.g., for preparing antimicrobial biomaterials. Recent studies have found that quaternary ammonium salt-modified antimicrobial monomers are cytotoxic. Therefore, it is of great significance to explore the cytotoxic mechanism of quaternary ammonium salt-modified antimicrobial monomers and determine possible cytoprotective measures for improving the biological safety of these antimicrobial resin-based materials and expanding their clinical applications. In addition, further validation of the clinical efficacy of these biomaterials is particularly important for accurately evaluating the clinical prospects of these biomaterials. Based on a literature review, this paper summarizes the applications and toxicity of biomedical materials modified with quaternary ammonium salts.

Relationship between high expression of efflux pump AcrAB-TolC induced by quaternary ammonium compound and fluoroquinolones resistance in Escherichia coli / 中华微生物学和免疫学杂志

Objective To investigate the mechanism of efflux pump AcrAB-TolC involved in the cross-resistance between quaternary ammonium compounds ( QAC) and fluoroquinolones ( FQ) in Escherich-ia coli. Methods Seventy-eight Escherichia coli strains were isolated from clinical samples and then tested for the sensitivity to benzalkonium bromide by ager dilution method. Six strains were randomly selected and induced with benzalkonium bromide. Changes in the sensitivity of these strains to benzalkonium bromide and ciprofloxacin were analyzed after induction. Expression of the efflux pump genes acrA, acrB and tolC at mRNA level in the induced strains and their parent strains were detected by quantitative real-time PCR. Re-sults Among the 78 strains, the minimum inhibitory concentrations ( MIC) ranged from 8 μg/ml to 64μg/ml and 47. 4％ of strains have higher MIC than the standard strain. Compared with the parent strains, the induced strains showed higher expression of acrA and tolC genes, and the differences between the two groups were statistically significant. The MIC values of ciprofloxacin to the six induced strains were 4-8 times higher than those to their parent strains. Conclusions It was speculated that the increased expression of acrA and tolC genes at transcription level in the induced strains were related to the cross-resistance between quaternary ammonium compounds and fluoroquinolone antibiotics.

Eficácia do álcool etílico e quaternário de amônio na desinfecção de equipamentos médicos hospitalares / Efficacy of ethyl alcohol and quaternary ammonium in hospital medical equipment disinfection / Eficacia del alcohol etílico y cuaternario de amonio en la desinfección de equipos médicos hospitalarios

Justificativa e Objetivos: Os ambientes hospitalares podem albergar microrganismos patogênicos e oportunistas, sendo o processo de limpeza e desinfecção importante para o controle das Infecções relacionadas à Assistência à Saúde (IRAS). Assim, o objetivo deste trabalho foi avaliar a eficácia do álcool etílico e do quaternário de amônio no processo de desinfecção de equipamentos médicos hospitalares previamente contaminados com Staphylococcus aureus (S. aureus). Métodos: descontaminação de 10 equipamentos médicos hospitalares contaminados com uma suspensão de S. aureus ATCC 25923. A descontaminação ocorreu com álcool etílico nas concentrações de 46,2%, 70% e 99% e com o quaternário de amônio de 1ª e de 5ª geração. Após a descontaminação, foram colhidas amostras da superfície dos equipamentos para cultura bacteriana. Resultados: foi verificado crescimento bacteriano em 80% dos equipamentos descontaminados com álcool 46,2% e 99%. Não houve crescimento bacteriano na superfície dos equipamentos descontaminados com álcool 70% e quaternários de amônio. Conclusão: os processos de desinfecção com álcool 70% e quaternário de amônio de 1ª e 5ª geração foram eficazes no controle do S. aureus, comprovando a ação efetiva destes produtos na desinfecção dos equipamentos médicos hospitalares.(AU)

Background and Objectives: Hospital environments may harbor pathogenic and opportunistic microorganisms, and the cleaning and disinfection process is important for the control of Health Care Related Infections (IRAS). Thus, the objective of this work to evaluate compare the efficacy of ethyl alcohol and quaternary ammonium in the disinfection of hospital medical equipment against Staphylococcus aureus (S. aureus). Methods: decontamination of 10 hospital medical equipment contaminated with a suspension of S. aureus ATCC 25923. The decontamination occurred with ethyl alcohol at concentrations of 46.2%, 70% and 99% and with the quaternary ammonium of 1st generation and 5th generation. After the decontamination, samples were harvested from the surface of the equipment for bacterial culture. Results: bacterial growth was verified in 80% of the equipment decontaminated with alcohol 46.2% and 99%. There was no bacterial growth on the surface of equipment decontaminated with alcohol 70% and quaternary ammonium. Conclusions: the disinfection processes with alcohol 70% and quaternary ammonium 1st and 5th generation were effective in the control of S. aureus, proving the effectiveness of these products in the disinfection of hospital medical equipment.(AU)

Justificación y objetivos: Los ambientes hospitalarios pueden albergar microorganismos patógenos y oportunistas, siendo el proceso de limpieza y desinfección importante para el control de las Infecciones relacionadas a la Asistencia a la Salud (IRAS). Así, el objetivo de este trabajo evaluar comparar la eficacia del alcohol etílico y del cuaternario de amonio en el proceso de desinfección de equipos médicos hospitalarios previamente contaminados con Staphylococcus aureus (S. aureus). Métodos: la descontaminación de 10 equipos médicos hospitalarios contaminados con una suspensión de S. aureus ATCC 25923. La descontaminación ocurrió con alcohol etílico en las concentraciones de 46,2%, 70% y 99% y con el cuaternario de amonio de 1ª y de 5ª generación. Después de la descontaminación, se tomaron muestras de la superficie de los equipos para cultivo bacteriano. Resultados: se verificó crecimiento bacteriano en el 80% de los equipos descontaminados con alcohol 46,2% y 99%. No hubo crecimiento bacteriano en la superficie de los equipos descontaminados con alcohol 70% y cuaternarios de amonio. Conclusión: los procesos de desinfección con alcohol 70% y cuaternario de amonio de 1ª y 5ª generación fueron eficaces en el control del S. aureus, comprobando la acción efectiva de estos productos en la desinfección de los equipos médicos hospitalarios.(AU)

Consecuencias del amonio en la fatiga central en atletas, posible efecto neuroprotector del ejercicio / Ammonium consequences in athletes' central fatigue and its possible neuroprotection effect thanks to physical activity / Consequências do amônio na fadiga central em atletas, possível efeito neuroprotetor do exercício

Introducción. La fatiga central en el deporte está asociada a los efectos del amonio. La principal fuente de producción de amonio durante el ejercicio es el músculo esquelético. El amonio se genera como consecuencia del metabolismo energético, debido a la oxidación de aminoácidos y a la desaminación del nucleótido de adenosin trifosfato. Objetivo. Presentar una reflexión sobre el efecto del amonio durante el ejercicio de alta intensidad y su relación con la fatiga central en atletas. Discusión. Durante el ejercicio, la concentración de amonio alcanza valores superiores a 200µM (micromolar); sin embargo, en un adulto promedio se considera que valores superiores a 60µM en sangre manifiestan un trastorno por hiperamonemia. El amonio influye en la disminución del rendimiento en atletas y está asociado con los efectos nocivos para la salud en pacientes con encefalopatía hepática. Conclusiones. La práctica del ejercicio físico genera neuroprotección contra las altas concentraciones de amonio en el cerebro, pues, durante el ejercicio con altas concentraciones de amonio, los atletas no presentan los síntomas de pacientes con encefalopatía hepática, lo que implica adaptaciones metabólicas que juegan un papel importante en el metabolismo del amonio en el cerebro. [Porras-Álvarez J. Consecuencias del amonio en la fatiga central en atletas, posible efecto neuroprotector del ejercicio. MedUNAB. 2018;21(1): 115-121 doi: 10.29375/01237047.3394].

Introduction. Central fatigue in sports training is associated with ammonium effects within the human body. The ammonium main production source during physical training is located in skeletal muscles and it is generated as a result of energy metabolism. This process is caused by amino acids oxidation and adenosine triphosphate nucleotide deamination. Objective. This article's objective is to present an analysis regarding ammonium effects when high intensity sports are performed and its relation with central fatigue in athletes. Discussion. When high intensity sport practices are performed, ammonium concentration levels can reach values higher than 200 µM (micromolar). However, it is considered that an average adult with ammonium levels higher than 60µM evidences a hyperammonemia disorder. Ammonium has direct influence in the decline of athletic performance and it is associated with harmful effects for hepatic encephalopathy patients. Conclusions. Physical activity practice creates neuroprotection against high-quantities of ammonium in the brain. Although in physical practices athletes have high amounts of ammonium, they do not show symptoms related to hepatic encephalopathy; thus, this situation implies that metabolic adaptations have an important role within ammonium metabolism in the brain. [Porras-Álvarez J. Ammonium consequences in athletes' central fatigue and its possible neuroprotection effect thanks to physical activity. MedUNAB. 2018;21(1):115-121doi: 10.29375/01237047.3394].

Introdução. A fadiga central no esporte está associada aos efeitos do amônio. A fonte de produção do amônio mais importante durante o exercício é o músculo esquelético. O amônio é gerado como consequência do metabolismo energético, devido à oxidação dos aminoácidos e à desaminação do trifosfato de adenosina. Objetivo. Apresentar uma reflexão sobre o efeito do amônio durante o exercício de alta intensidade e sua relação com a fadiga central em atletas. Discussão. Durante o exercício, a concentração do amônio atinge valores superiores a 200µM (micromol); no entanto, em um adulto médio, considera-se que valores superiores a 60µM no sangue mostram um distúrbio por hiperamonemia. O amônio influencia a diminuição do desempenho em atletas e está associado a efeitos nocivos para a saúde em pacientes com encefalopatia hepática. Conclusões. A prática de exercício físico gera neuroproteção contra altas concentrações do amônio no cérebro, pois, durante o exercício com altas concentrações do amônio, os atletas não apresentam sintomas de encefalopatia hepática, o que implica adaptações metabólicas que desempenham um papel importante no metabolismo do amônio no cérebro. [Porras-Álvarez J. Consequências do amônio na fadiga central em atletas, possível efeito neuroprotetor do exercício. MedUNAB. 2018;21(1):115-121doi: 10.29375/01237047.3394].

Determination of quaternary ammonium alkaloid content inLycium ruthenicumMurr. and qualitative analysis of its nitrogenous compounds / 国际中医中药杂志

Objective The aims of this study were to develop an ultraviolet-visible spectrophotometry (UV-Vis) for the determination of quaternary ammonium alkaloid content in Lycium ruthenicumMurr., and to analysis the constitution of its nitrogenous compounds by liquid chromatograph - mass spectrometry(LC-MS). Methods The quaternary ammonium alkaloid content was determined by a UV-Vis spectrophotometer at 524 nm. The ultra performance liquid chromatography(UPLC) analysis was performed on BOS Hypersil C18 column(2.1 mm × 150 mm, 2.4μm), with 0.1％ formic acid solution(A)–acetonitrile(B) as the mobile phase for gradient elution. The flow rate was 0.3 ml/min, and the column temperature was 35℃, Multiple reaction monitoring (MRM) equipped with electrospray ion source was performed in positive ion mode for structure analysis.Results As a standard, the betaine was linear in the range of 981μg-4906μg,Y=0.0001X-0.0055, r=0.9993, and the average recovery rate was 98.53％,RSD=1.19％(n=6). There were 12 nitrogenous compounds analyzed by LC-MS, with N(1)-dihydrocaffeoyl-N(12)-caffeoyl spermine and p-Hydroxyl-cinnamyl-dihydrocaffeoyl spermidine were first reported.Conclusions The method developed in this subject is simple, accurate with good repeatability, which can be applied for determination of quaternary ammonium alkaloid content in Lycium ruthenicumMurr. And the structure analysis of its nitrogenous compounds will deepen the understanding of the compounds inLycium ruthenicumMurr.

Antibacterial dental adhesive containing nanoantibacterial inorganic fillers / 华西口腔医学杂志

OBJECTIVE@#This investigation aimed to develop a novel antibacterial dental adhesive containing nanoantibacterial inorganic fillers and measure the dentin bonding strength, mechanical properties, and antibacterial property of the novel adhesive in vitro.@*METHODS@#Novel nanoantibacterial inorganic fillers containing quaternary ammonium salt with long chain alkyl were synthesized on the basis of previous research. These novel nanoantibacterial inorganic fillers were added into the dental adhesive to prepare novel nanoantibacterial dental resin composite at mass fractions of 0%, 2.5%, 5.0%, 7.5%, and 10%; 0% was used as control. Dentin shear bonding test was used to evaluate the bonding strength. Flexural test was utilized to measure the novel resin composite flexural strength and elastic modulus. A dental plaque microcosm biofilm model with human saliva as inoculum was formed. Colony forming unit, lactic acid production, and live/dead assay of the biofilm on novel dental adhesive were calculated to assess the effect of novel dental adhesive on human dental plaque microcosm biofilm.@*RESULTS@#The dentin shear bond strength, flexural strength, and elastic modulus were 28.9 MPa, 86.6 MPa, and 4.2 GPa, respectively, when the nanoantibacterial inorganic filler mass fraction in the dental adhesive reached approximately 5.0%. Consequently, the dentin shear bond strength and mechanical properties significantly increased. Addition of 2.5% nanoantibacterial inorganic fillers into the dental adhesive exerted no adverse effect on the mechanical properties significantly (P>0.05). Dental adhesive containing 5% or more nanoantibacterial inorganic fillers inhibited the metabolic activity of the dental plaque microcosm biofilm significantly, thereby displaying a strong antibacterial potency (P<0.05).@*CONCLUSIONS@#This novel antibacterial dental adhesive, which contained 5.0% nanoantibacterial inorganic filler, exhibited promising bonding strength, mechanical property, and antibacterial ability. Hence, this adhesive can be potentially used in caries inhibition in dental application.

Non-leaching, broad-spectrum antibacterial poly (ε-caprolactone)/gelatin-QAS nanofiberous membranes for wound dressing / 生物医学工程学杂志

5-20 wt% trimethoxysilylpropyl octadecyldimethyl ammonium chloride (QAS) was used to modify Poly (ε-caprolactone) (PCL)-gelatin hybrid to fabricate non-leaching antibacterial nanofiber membranes (PG-Q) by electrospinning. The results from scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that the QAS leaded to phase separation between the QAS and PCL. Hydrophilic test demonstrated that the PG-Q nanofiber membranes had hydrophobic surface, which was help for peeling off the dressing from the wound. Additionally, the physical and chemical cross-linking between the QAS/PCL and QAS/gelatin were confirmed by Fourier transform infrared (FTIR), which were good for long lasting antibacterial effect. The PG-Q membranes also showed excellent cell-biocompatibility. Furthermore, compared with pure PCL nanofiber membrane, the PG-Q nanofiber membranes, especially PG-Q15 (QAS: 15 wt%) and PG-Q20 (QAS: 20 wt%), showed a considerable increase in the bacteriostatic rate of and (more than 99% after 12 h). Therefore, electrospinning non-leaching antibacterial nanofiber membranes could be an optimal choice for antibacterial wound dressing.

Use of green fluorescent protein labeled non-tuberculous mycobacteria to evaluate the activity quaternary ammonium compound disinfectants and antibiotics

Abstract Although infections with NonTuberculous Mycobacteria have become less common in AIDS patients, they are important opportunistic infections after surgical procedures, likely because they are ubiquitous and not efficiently killed by many commonly used disinfectants. In Venezuela there have recently been many non-tuberculous mycobacteria soft tissue infections after minor surgical procedures, some apparently related to the use of a commercial disinfectant based on a Quaternary Ammonium Compound. We studied the activity of this and other quaternary ammonium compounds on different non-tuberculous mycobacteria by transforming the mycobacteria with a dnaA-gfp fusion and then monitoring fluorescence to gauge the capacity of different quaternary ammonium compounds to inhibit bacterial growth. The minimum inhibitory concentration varied for the different quaternary ammonium compounds, but M. chelonae and M. abscessus were consistently more resistant than M. smegmatis, and M. terrae more resistant than M. bovis BCG.

Engineered Protein Nanopore for Real-time Monitoring Single-molecule Reaction between Cadmium Ion and Glutathione / 分析化学

The chelating reaction between glutathione peptides and divalent cadmium ion was used as a typical model for investigating the coordination chemistry of SH-containing peptides and heavy metal ions, which was essential to understand the mechanism of intracellular cadmium detoxification.Here, the mutant (CM113R)7 αHL protein nanopore equipped with a first synthesized per-6-quaternary ammonium-β-cyclodextrin (p-QABCD) was used as nanoreactor and detector to investigate the single-molecule reaction of GSH molecules and Cd2+ ions.Different reaction pathways, intermediates, and products could be recognized.Cd2+-GSH reaction was highly dependent on the solution pH.The Cd(GSH)2 was formed at pH 7.4, while the Cd(GSH)2 and Cd2(GSH)2 were formed at pH 9.0.Cd2(GSH)2 was formed by two possible pathways: (1) A Cd2+ ion primarily coordinated with the thiol group of two GSH molecules to form Cd(GSH)2, and then the second Cd2+ ion quickly incorporated with the deprotonated amino group of Cd(GSH)2 to form Cd2(GSH)2;(2) Two Cd2+ ions separately coordinated with the thiol and deprotonated amino group of one GSH molecule to form Cd2(GSH)1, and the second GSH molecule quickly bounded to Cd2+ ions to form Cd2(GSH)2.This work studied the chelating reaction between metal ions and bioactive glutathione at single-molecule level without labeling and chemical modification, and would be important to further understand intracellular mechanisms of detoxification of heavy metals and greatly expand the research field of nanopore single-molecule technique.

Disinfection for Prosthetic Sockets in 19 Wearers / 中国康复理论与实践

Objective To explore the possibities of routine disinfection for prosthetic sockets. Methods From June to August, 2016, 19 lower limbs prosthesis wearers wiped their prosthetic socket surfaces and sprayed the stump socks with a compound of quaternary ammoni-um salt every night for three weeks. Meanwhile, field investigation and sampling were carried out weekly. Staphylococcus aureus, Pseudo-monas aeruginosa, Escherichia Coli and Candida albicans were isolated and identified, and colony counting was carried out. Results After disinfection, the number of bacteria on the prosthetic socket reduced 1.8-3.0 log, and the number of fungi reduced 1.6-1.9 log. One strain of Staphylococcus aureus and one strain of Escherichia Coli were isolated before disinfection and one strain of Pseudomonas aeruginosa was isolated after disinfection. Eczema and itching symptoms relieved or disappeared and deodorant effect was distinguished after continuous disinfection. Conclusion Disinfection on prosthetic sockets with compound of quaternary ammonium salt may control the microbial contam-ination and odor, reduce the incidence of eczema and other skin diseases.

Preparation of DNA-loaded chitosan nanoparticle vaccine / 药学实践杂志

Objective To study and optimize the preparation condition of pVAX1‐wapA‐loaded nanoparticles and deter‐mine the transfection efficiency .Methods The related effects of the crucial factors for the formation of nanoparticles:concen‐tration of chitosan and TPP ,pH value ,N/P ratio were studied by single‐factor experiment ,with nanoparticles size and zeta potential as index .Cell transfection test was carried out to indicate that enhancement of cell transfection efficiency of nano‐car‐rier .Results Nanoparticles loaded DNA vaccine were nearly spherical shape with uniform particle size chitosan nanoparticle (CS) ,(219 .2 ± 18 .2) nm ;quaternary ammonium chitosan nanoparticles(CSTM) ,(222 .5 ± 15 .6) nm .Zeta potential of CS and CSTM was (24 .7 ± 3 .5) mV ,(19 .6 ± 1 .2) mV and encapsulation efficiency was 91 .24% ,87 .66% ,respectively .CSTM nano‐particle could enhance cellular uptake of pVAX1‐wapA obviously .Conclusion CSTM nanoparticle was proved to be an efficient DNA vaccine delivery vector .