Poly-3-hydroxybutyrate-silver nanoparticles membranes as advanced antibiofilm strategies for combatting peri-implantitis.

Dental implant success is threatened by peri-implantitis, an inflammation leading to implant failure. Conventional treatments struggle with the intricate microbial and host factors involved. Antibacterial membranes, acting as barriers and delivering antimicrobials, may offer a promising solution. Thus, this study highlights the potential of developing antibacterial membranes of poly-3-hydroxybutyrate and silver nanoparticles (Ag Nps) to address peri-implantitis challenges, discussing design and efficacy against potential pathogens. Electrospun membranes composed of PHB microfibers and Ag Nps were synthesized in a blend of DMF/chloroform at three different concentrations. Various studies were conducted on the characterization and antimicrobial activity of the membranes. The synthesized Ag Nps ranged from 4 to 8 nm in size. Furthermore, Young's modulus decreased, reducing from 13.308 MPa in PHB membranes without Ag Nps to 0.983 MPa in PHB membranes containing higher concentrations of Ag Nps. This demonstrates that adding Ag Nps results in a less stiff membrane. An increase in elongation at break was noted with the rise in Ag Nps concentration, from 23.597 % in PHB membranes to 60.136 % in PHB membranes loaded with Ag Nps. The antibiotic and antibiofilm activity of the membranes were evaluated against Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus mutans, and Candida albicans. The results indicated that all PHB membranes containing Ag Nps exhibited potent antibacterial activity by inhibiting the growth of biofilms and planktonic bacteria. However, inhibition of C. albicans occurred only with the PHB-Ag Nps C membrane. These findings emphasize the versatility and potential of Ag Nps-incorporated membranes as a multifunctional approach for preventing and addressing microbial infections associated with peri-implantitis. The combination of antibacterial and antibiofilm properties in these membranes holds promise for improving the management and treatment of peri-implantitis-related complications.

Thermal Injury Protocol to Study Healing, With and Without Infection, in Guinea Pig (Cavia porcellus) Model / Protocolo de Lesión Térmica, para Estudio de Cicatrización, en Modelo Animal Cobayo (Cavia porcellus)

SUMMARY: Experimental healing studies in humans are complex and difficult to replicate in vitro. Hence, animal models are needed to study the different stages involved. The guinea pig (Cavia porcellus) is a model close to human physiology, including the lack of vitamin C synthesis, a precursor of collagen fibers for healing. The thermal injury in this animal makes it possible to study all the stages of healing, taking few days to show tissue repair in the processes with and without localized infection. The aim of this work was to systematize an experimental guinea pig (Cavia porcellus) animal model protocol for studies on healing with and without localized infection.

Los estudios experimentales de cicatrización en humanos son complejos, difícilmente replicables in vitro, por lo que se hace necesarias modelos animales que permitan el estudio de las distintas etapas que ella implica. El cobayo (Cavia porcellus) resulta ser un modelo cercano a la fisiología humana, incluyendo la falta síntesis de vitamina C precursora de fibras colágenas para la cicatrización. La lesión térmica en este animal, permite estudiar todas las etapas de la cicatrización, mostrando pocos días en la reparación tisular, tanto en proceso con y sin infección localizada. El objetivo de este trabajo fue sistematizar un protocolo de modelo animal experimental en cobayo (Cavia porcellus) para estudios de cicatrización con y sin infección localizada.

Influencia de la seropositividad contra adenovirus-36 sobre riesgo de obesidad y resistencia a la insulina en población infanto-juvenil de la Región de la Araucanía / Influence of adenovirus 36 seropositivity on the risk of obesity and insulin resistance in a population of children and adolescents from the Región de la Araucanía

La infección previa por el adenovirus-36 (Ad-36) se ha asociado con el proceso adipogénico y el control glicémico en modelos experimentales de cultivos celulares y animales. En humanos, la presencia de anticuerpos contra Ad-36 ha mostrado aumentar el riesgo de obesidad y, paradójicamente, mejorar el control glicémico en diferentes poblaciones. Se evaluó la influencia de la seropositividad contra Ad-36 sobre riesgo de obesidad, el perfil lipídico y glicémico en una población de niños en edad escolar. Métodos: Doscientos ocho individuos de entre 9 y 13 años se agruparon según estado nutricional como normopeso (IMC z-score de -1 a +1), con sobrepeso (IMC z-score de +1 a +2) y con obesidad (IMC z-score > +3). Se evaluaron medidas antropométricas, desarrollo puberal según Tanner y parámetros bioquímicos (perfil lipídico, glucemia e insulina) y la seropositividad contra Ad-36. Se determinó la resistencia a la insulina (RI) según criterio para la población infantil chilena. La seropositividad contra Ad-36 se determinó mediante ELISA. Resultados: Hubo una alta prevalencia de sobrepeso/obesidad en la población de estudio. La seropositividad contra Ad-36 fue del 5,4% en el grupo total, pero no se observó una asociación con el estado nutricional. No se encontró correlación entre la seropositividad contra Ad-36 y los parámetros del perfil lipídico. La insulina y la HOMA-RI fueron significativamente más bajas en el grupo Ad-36 (+) (p<0,001), no habiendo sido reportados casos de RI en el grupo Ad-36 (+) en nuestra población. Conclusiones: Nuestros resultados sugieren que la infección previa por el adenovirus-36 afecta la secreción de insulina y la resistencia a la insulina, como se ha descrito anteriormente, sin embargo, no se observa correlación con el desarrollo de la obesidad infantil en la población pediátrica del sur de Chile.

Previous infection with Adenovirus-36 (Ad-36) has been associated with adipogenic process and glycemic control in experimental models of cell culture and animals. In humans, the presence of antibodies against Ad-36 has been shown to increase the risk of obesity and, paradoxically, improve glycemic control in different populations. The influence of Ad-36 seropositivity on obesity risk, lipid and glycemic profile was evaluated in a population of school-age children. Methods: Two hundred eight individuals aged 9 to 13 years were grouped according to their nutritional status as normal weight (BMI z-score from -1 to +1), overweight (BMI z-score from +1 to +2) or obese (BMI z-score from -1 to +1). z-score > +3). Anthropometric measurements, pubertal development according to Tanner stage, biochemical parameters (lipid profile, glycemia and insulin) and seropositivity against Ad-36 were evaluated. Insulin resistance (IR) was determined according to criteria for the Chilean child population. Seropositivity against Ad-36 was determined by ELISA. Results: There was a high prevalence of overweight/obesity in the study population. Seropositivity against Ad-36 was 5.4% in the total group, but no association with nutritional status was observed. No correlation was found between Ad-36 seropositivity and lipid profile parameters. Insulin and HOMA-RI were significantly lower in the Ad-36 (+) group (p<0.001), and no cases of RI were reported in the Ad-36 (+) group in our population. Conclusions: Our results suggest that previous adenovirus-36 infection affects insulin secretion and insulin resistance, as previously described, however, no correlation is observed with the development of childhood obesity in the pediatric population. from southern Chile.

Association of Progranulin Gene Expression from Dyspeptic Patients with Virulent Helicobacter pylori Strains; In Vivo Model.

(1) Background: Gastric cancer, the fourth most common cause of death from tumors in the world, is closely associated with Helicobacter pylori. Timely diagnosis, therefore, is essential to achieve a higher survival rate. In Chile, deaths from gastric cancer are high, mainly due to late diagnosis. Progranulin has reflected the evolution of some cancers, but has been poorly studied in gastric lesions. Aiming to understand the role of progranulin in H. pylori infection and its evolution in development of gastric lesions, we evaluated the genic expression of progranulin in gastric tissue from infected and non-infected patients, comparing it according to the epithelial status and virulence of H. pylori strains. (2) Methods: The genic expression of progranulin by q-PCR was quantified in gastric biopsies from Chilean dyspeptic patients (n = 75) and individuals who were uninfected (n = 75) by H. pylori, after receiving prior informed consent. Bacteria were grown on a medium Columbia agar with equine-blood 7%, antibiotics (Dent 2%, OxoidTM), in a microaerophilic environment, and genetically characterized for the ureC, vacA, cagA, and iceA genes by PCR. The status of the tissue was determined by endoscopic observation. (3) Results: Minor progranulin expression was detected in atrophic tissue, with a sharp drop in the tissue colonized by H. pylori that carried greater virulence, VacAs1m1+CagA+IceA1+. (4) Conclusions: Progranulin shows a differential behavior according to the lesions and virulence of H. pylori, affecting the response of progranulin against gastric inflammation.

MALDI-TOF MS and 16S RNA Identification of Culturable Gastric Microbiota: Variability Associated with the Presence of Helicobacter pylori.

Helicobacter pylori is the main bacteria associated with gastroduodenal diseases. Recent studies have reported that gastric microbiota might be modified by the H. pylori colonization, favoring gastric lesions' development. In Chile, the region of La Araucanía concentrates a high risk of gastric cancer associated with Helicobacter pylori colonization, rurality, poverty, and Mapuche ethnicity. Hence, we aimed to identify the culturable gastric microbiota and characterize its variability at different stages of epithelial injury, based on its H. pylori colonization in dyspeptic patients from this Chilean region. Microaerophilic bacteria strains were isolated from antrum biopsies of 155 dyspeptic patients' biopsies and identified using MALDI-TOF MS or 16sRNA gene sequencing for non-pylori species identification, and UreC gene amplification for H. pylori confirmation. We found 48 species from 18 families, mainly belonging to Neisseriaceae (21.3%), Streptococcaceae (20.0%), Actynomicetaceae (9.0%), Enterobacteriaceae, and Lactobacillaceae (4.5%); however, Streptococcaceae and Actinomycetaceae families showed a significant reduction in samples infected with H. pylori, along with a considerably lower diversity of species. Our results revealed a microbiota modification due to H. pylori colonization associated with the gastric epithelial state, suggesting a potential microbiota role for developing and progressing gastric diseases.

Influence of adenovirus 36 seropositivity on the expression of adipogenic microRNAs in obese subjects.

BACKGROUND: Infection by Adenovirus 36 (Ad-36) has been associated with adipogenesis using cell and animal models, and a high risk of developing obesity has been reported in Ad-36-seropositive individuals. However, molecular mechanisms involved in the maintenance over the years of adipogenesis associated with Ad-36 has not been investigated in human adipose tissue. Epigenetic mechanisms, such as micro-RNAs (miRNAs) that regulate gene expression at the post-transcriptional level, have shown an important role in the development and maintenance of metabolic diseases. AIM: This study investigated the expression of miRNA associated with the adipogenic process in visceral adipose tissue from obese individuals according to Ad-36 serology. METHODS: Obese individuals were separated according to their status of Ad-36 serology in seropositive (Ad-36 (+); n = 29) and seronegative (Ad-36 (-); n = 28) groups. Additionally, a group of lean controls (n = 17) was selected to compare with obese individuals. Biopsies of visceral adipose tissue were obtained to evaluate miRNA and gene expression. The study of Ad-36 serology was carried out by ELISA. The expression of pro-adipogenic (miR-17 and miR-210) and anti-adipogenic (miR-155, miR-130 and miR-27a) miRNAs was evaluated using Taqman advanced miRNA assays by qPCR. The expression of adipogenes encoding LEP, ADIPOQ, and PPARγ was evaluated by Taqman predesigned assays through qPCR. RESULTS: The obese group had higher LEP (p < 0.001) and PPARγ (p = 0.016) expression and lower ADIPOQ expression (p = 0.017), and also had higher expression of miR-210 (p = 0.039), whereas lower expression of miR-155 (p = 0.019) and miR-27a (p = 0.028) as compared to lean controls. Higher PPARγ expression (p = 0.008), but no influence on LEP or ADIPOQ expression was observed in Ad-36 (+) group. Those seropositive individuals also had higher expression of the miR-17 (p = 0.028) and lower levels of miR-155 (p = 0.031) in adipose tissue as compared to seronegative subjects. CONCLUSIONS: Individuals with previous infection by Ad-36 had higher expression of the pro-adipogenic miR-17 and lower expression of the anti-adipogenic miR-155, which could lead to an increased adipogenic status by positively modulating PPARγ expression in adipose tissue from obese subjects.

Adenovirus 36 seropositivity is related to obesity risk, glycemic control, and leptin levels in Chilean subjects.

BACKGROUND: Adenovirus 36 (Ad-36) has been associated to adiposity in animal and in vitro studies. Ad-36 seropositivity has also been reported to contribute to obesity risk in children and adult populations. We investigated the relationship of Ad-36 serology with obesity and metabolic parameters in a Chilean population. SUBJECTS AND METHODS: Clinical and anthropometric data were obtained and blood samples were drawn from 99 lean (BMI: 18.5-24.9 kg/m2) and 151 obese (BMI > 30 kg/m2) subjects. Laboratory tests included lipid profile as well as glucose, insulin, leptin, and adiponectin levels. Ad-36 seropositivity was evaluated in serum samples by enzyme-linked immunosorbent assay. RESULTS: Seroprevalence of Ad-36 was higher in the obese group (58%) than in lean controls (34%) demonstrating that individuals previously infected with Ad-36 have higher risk of obesity in the study population (OR: 2.67, 95%CI: 1.58-4.51, p < 0.001). Interestingly, Ad-36 was related to lower concentrations of triglycerides and VLDL cholesterol in lean subjects (p = 0.049) and lower leptin in obese individuals (p = 0.014). Previous Ad-36 infection was also related to lower glycemia, insulinemia, and HOMA-IR (p < 0.05) in obese subjects who were not under antidiabetic drugs. CONCLUSIONS: Our results provide evidence of the contribution of previous Ad-36 infection to an increased risk of obesity in adult Chilean population. Ad-36 seropositivity was also associated to lipid profile, glycemic control, and leptin levels in adult Chilean population.

Prevalence of Infection and Antibiotic Susceptibility of Helicobacter pylori: An Evaluation in Public and Private Health Systems of Southern Chile.

Helicobacter pylori colonizes half of the human population. Age, ethnicity, and socioeconomic status are factors that influence the prevalence of the infection. This is important in southern Chile, one of the most unequal regions in the world, where a significant difference in the health access of the population occurs due to the existence of two competing health systems. Moreover, in the last few years, current protocols of H. pylori eradication have shown high rates of resistance with reduced therapeutic efficacy. This study reported the epidemiology of infection and attempted to identify divergent points among the population beneficiaries of the two health care schemes in southern Chile. Biopsies from public (n = 143) and private (n = 86) health systems were studied. At the same time, clinical and sociodemographic factors were evaluated. H. pylori strains were obtained from gastric biopsies for culture and molecular testing. Antibiotic susceptibility was determined by the agar dilution method. Differences about ethnicity, rural residence, and education (p ≤ 0.05) were observed between beneficiaries of the two health systems. The prevalence of H. pylori was 45%, with no significant differences regardless of the socioeconomic conditions. The only identified risk factor associated with H. pylori infection was Mapuche ethnicity (OR (odds ratio) = 2.30). H. pylori showed high resistance rates, particularly against clarithromycin (40%), levofloxacin (43.1%), and metronidazole (81.8%). This study highlighted the importance of Mapuche ancestry as a risk factor in southern Chile and emphasized the need to search for new eradication strategies as well as further studies evaluating therapeutic efficacy.

High prevalence of CTX-M-1 group in ESBL-producing enterobacteriaceae infection in intensive care units in southern Chile.

Enterobacteria-producing extended-spectrum ß-lactamases (ESBL) play an important role in healthcare infections, increasing hospitalization time, morbidity and mortality rates. Among several ESBLs that emerge from these pathogens, CTX-M-type enzymes had the most successful global spread in different epidemiological settings. Latin America presents high prevalence of CTX-M-2 in ESBL-producing enterobacterial infections with local emergence of the CTX-M-1 group. However, this high prevalence of the CTX-M-1 group has not yet been reported in Chile. The aim of this study was to identify ESBLs among enterobacteria isolated from clinical samples of critically ill patients from southern Chile. One-hundred thirty seven ESBL-producing bacteria were isolated from outpatients from all critical patient units from Hernán Henríquez Aravena Hospital. Phenotype characterization was performed by antibiogram, screening of ESBL, and determination of minimum inhibitory concentration (MIC). PCR was used for genetic confirmation of resistance. Molecular typing was performed by ERIC-PCR. ESBL-producing isolates were identified as Klebsiella pneumoniae (n=115), Escherichia coli (n=18), Proteus mirabilis (n=3), and Enterobacter cloacae (n=1), presenting multidrug resistance profiles. PCR amplification showed that the strains were positive for blaSHV (n=111/81%), blaCTX-M-1 (n=116/84.7%), blaTEM (n=100/73%), blaCTX-M-2 (n=28/20.4%), blaCTX-M-9 (0.7%), blaPER-1 (0.7%), and blaGES-10 (0.7%). The multiple production of ESBL was observed in 93% of isolates, suggesting high genetic mobility independent of the clonal relationship. The high frequency of the CTX-M-1 group and a high rate of ESBL co-production are changing the epidemiology of the ESBL profile in Chilean intensive care units. This epidemiology is a constant and increasing challenge, not only in Chile, but worldwide.

High prevalence of CTX-M-1 group in ESBL-producing enterobacteriaceae infection in intensive care units in southern Chile

ABSTRACT Enterobacteria-producing extended-spectrum β-lactamases (ESBL) play an important role in healthcare infections, increasing hospitalization time, morbidity and mortality rates. Among several ESBLs that emerge from these pathogens, CTX-M-type enzymes had the most successful global spread in different epidemiological settings. Latin America presents high prevalence of CTX-M-2 in ESBL-producing enterobacterial infections with local emergence of the CTX-M-1 group. However, this high prevalence of the CTX-M-1 group has not yet been reported in Chile. The aim of this study was to identify ESBLs among enterobacteria isolated from clinical samples of critically ill patients from southern Chile. One-hundred thirty seven ESBL-producing bacteria were isolated from outpatients from all critical patient units from Hernán Henríquez Aravena Hospital. Phenotype characterization was performed by antibiogram, screening of ESBL, and determination of minimum inhibitory concentration (MIC). PCR was used for genetic confirmation of resistance. Molecular typing was performed by ERIC-PCR. ESBL-producing isolates were identified as Klebsiella pneumoniae (n = 115), Escherichia coli (n = 18), Proteus mirabilis (n = 3), and Enterobacter cloacae (n = 1), presenting multidrug resistance profiles. PCR amplification showed that the strains were positive for blaSHV (n = 111/81%), blaCTX-M-1 (n = 116/84.7%), blaTEM (n = 100/73%), blaCTX-M-2 (n = 28/20.4%), blaCTX-M-9 (0.7%), blaPER-1 (0.7%), and blaGES-10 (0.7%). The multiple production of ESBL was observed in 93% of isolates, suggesting high genetic mobility independent of the clonal relationship. The high frequency of the CTX-M-1 group and a high rate of ESBL co-production are changing the epidemiology of the ESBL profile in Chilean intensive care units. This epidemiology is a constant and increasing challenge, not only in Chile, but worldwide.

Implicancias estructurales y fisiológicas de la célula bacteriana en los mecanismos de resistencia antibiótica / Structural and physiological implications of bacterial cell in antibiotic resistance mechanisms

RESUMEN: La alta capacidad de adaptación de las bacterias a ambientes hostiles ha permitido el desarrollo de resistencia a antibacterianos, causando problemas de impacto mundial en la salud hospitalaria y de la comunidad, limitando las opciones terapéuticas lo que afecta el control de enfermedades, elevando las tasas de morbi-mortalidad. Esta capacidad de resistencia es mediada por factores estructurales y fisiológicos de las bacterias que actúan a diferentes niveles tanto extracelular como intracelular. A niveles extracelulares se destaca la capacidad de las poblaciones bacterianas en la formación de biopelículas y la regulación de señales celulares quorum sensing, permitiendo la evasión de la acción antibiótica. A nivel de envoltura celular se destaca el funcionamiento y comportamiento de la pared celular y de la membrana celular, principalmente por medio de la regulación de la expresión de canales de entrada o porinas y/ o bombas de expulsión que impiden el acceso o inducen la salida de antibióticos; otros mecanismos integran la modificación de la actividad de drogas por medio de la hidrólisis o modificación del sitio activo del fármaco. A nivel intracelular, las bacterias pueden cambiar los procesos de óxido/reducción, modificar los sitios objetivos del antibiótico e inactivar los grupos transfer, y modificar las subunidades ribosomales afectando la acción de los antibióticos que inhiben la síntesis de proteínas. A esto se añaden las modificaciones en la expresión génica y del código genético, que regula todos los anteriores, y es capaz de generar cambios adaptativos, resistencia a fármacos y desinfectantes, entre otros. La presente revisión tiene como objetivo describir las implicancias estructurales y fisiológicas de la célula bacteriana en los mecanismos de resistencia antibiótica considerando la organización estructural y fisiológica involucrada en los principales mecanismos de resistencia a antibióticos presentes en bacterias de importancia clínica que conllevan a fallas terapéuticas con alto costo en salud humana.

SUMMARY: The high adaptability of bacteria to hostile environments has favored antibacterial resistance development, impacting hospital and community healthcare worldwide. It has also affected disease control, limited therapeutic options and raised morbiditymortality rate. This resistance ability is mediated by structural and physiological factors of bacteria acting at both extracellular and cellular levels. The ability of bacterial populations in biofilm formation and regulation of cellular signal quorum sensing at the extracellular level, allows for the evasion of antibiotic action. At a cellular level, the performance and behavior of the cell wall and cell membrane is emphasized, mainly by regulating the expression of inlet channels or porins and/or expulsion pumps preventing access to, or inducing the outflow of antibiotics. Other mechanisms integrate modification of drug activity by hydrolysis or modification of the active site of the drug. Further into intracellular level, bacteria can change the oxidation/reduction processes; modify the target sites of the antibiotic and inactivate transfer groups. Bacteria can also modify the ribosomal subunits affecting the antibiotics which inhibit protein synthesis, and cause modifications of gene expression and genetic code that regulate the above mechanism. These may also generate adaptive changes and resistance to drugs and disinfectants. The aim of the present review is to describe the structural and physiological implications of bacterial cell in the mechanisms of antibiotic resistance. The study also considered the structural and physiological organization involved in the main mechanisms of antibiotic resistance in bacteria relevant to clinical healthcare.

Effects of clopidogrel on inflammatory cytokines and adhesion molecules in human endothelial cells: Role of nitric oxide mediating pleiotropic effects.

INTRODUCTION: Clopidogrel is commonly used in prevention and treatment of atherothrombosis. Some previous studies have suggested a pleiotropic effect of clopidogrel; however, when this drug causes platelet-independent effects on endothelial function remains unclear. AIMS: To evaluate the influence of clopidogrel on inflammatory biomarkers and adhesion molecules in human endothelial cells and the role of nitric oxide (NO) in this process. METHODS: TNF-α-induced human umbilical vein endothelial cells (HUVEC) were exposed to clopidogrel. Gene expression and protein expression of ICAM-1, P-selectin, IL-8, IL-6, and MCP-1 were evaluated by qPCR, flux cytometry, or milliplex technology. Expression of endothelial nitric oxide synthase (NOS3) and NO release were also evaluated. Influence of clopidogrel was further evaluated in NOS3 downregulated HUVEC by RNAi. RESULTS: Clopidogrel at 20 µmol/L induced NO release in HUVEC after 24-hours treatment. Gene expressions of inflammatory markers IL-8 and MCP1 were reduced after clopidogrel treatment (P<.05); however, only MCP-1 remained reduced at protein level. IL-6 was not modified by clopidogrel treatment. Gene expression and protein expression of ICAM-1 were diminished by 24-hours clopidogrel exposure, whereas P-selectin was not modified. NOS3 downregulated HUVEC model revealed that ICAM-1 modification by clopidogrel is dependent of this via, whereas MCP-1 is modulated in an NO-independent form. CONCLUSIONS: Our results support new evidence for pleiotropic effects of clopidogrel on inflammation and endothelial function. Reduction in ICAM-1 and MCP-1 in human endothelium is an important extent of the use of this drug for treatment of cardiovascular diseases, and NO has an important role in this process.

Nanopartículas Sintetizadas por Bacterias Antárticas y sus Posibles Mecanismos de Síntesis / Nanoparticles Synthesized by Antarctic Bacteria and their Possible Mechanisms of Synthesis

En los últimos años microorganismos tales como hongos, levaduras y, en especial, las bacterias han sido utilizadas para realizar biosíntesis de nanopartículas. Existen varios tipos de bacterias descritas como productoras de nanopartículas, sin embargo, las bacterias psicrófilas y psicrotolerantes no han sido ampliamente estudiadas, aun cuando su utilización en la producción de nanopartículas podría entregar ventajas relacionadas con su estabilidad, el gasto energético de su producción, al mismo tiempo que son una alternativa amigable con el medio ambiente. Este artículo entrega una breve revisión de las bacterias antárticas psicrófilas y psicrotolerantes sintetizadoras de nanopartículas, los posibles mecanismos que se asocian a esta síntesis y perspectivas futuras relacionadas a la biosíntesis bacteriana de nanopartículas.

In recent years microorganisms as fungi, yeasts and especially bacteria have been used to produce nanoparticles biosynthesis. Several types of bacteria are described as nanoparticles producers, however, psychrophilic and psychrotolerant bacterias have not been studied widely, although its use in the production of nanoparticles could provide advantages related to the stability of nanoparticles, energy expenditure on its production, while being an environmentally friendly alternative. This article provides a brief overview of Antarctic bacterias, both psychrophilic and psychrotolerant that synthesis nanoparticles, possible mechanisms associated to this synthesis and future perspectives related to bacterial biosynthesis of nanoparticles.

Effects of clopidogrel on inflammatory cytokines and adhesion molecules in human endothelial cells: Role of nitric oxide mediating pleiotropic effects

NTRODUCTION: Clopidogrel is commonly used in prevention and treatment of atherothrombosis. Some previous studies have suggested a pleiotropic effect of clopidogrel; however, when this drug causes platelet-independent effects on endothelial function remains unclear. AIMS: To evaluate the influence of clopidogrel on inflammatory biomarkers and adhesion molecules in human endothelial cells and the role of nitric oxide (NO) in this process. METHODS: TNF-α-induced human umbilical vein endothelial cells (HUVEC) were exposed to clopidogrel. Gene expression and protein expression of ICAM-1, P-selectin, IL-8, IL-6, and MCP-1 were evaluated by qPCR, flux cytometry, or milliplex technology. Expression of endothelial nitric oxide synthase (NOS3) and NO release were also evaluated. Influence of clopidogrel was further evaluated in NOS3 downregulated HUVEC by RNAi. RESULTS: Clopidogrel at 20 μmol/L induced NO release in HUVEC after 24-hours treatment. Gene expressions of inflammatory markers IL-8 and MCP1 were reduced after clopidogrel treatment (P<.05); however, only MCP-1 remained reduced at protein level. IL-6 was not modified by clopidogrel treatment. Gene expression and protein expression of ICAM-1 were diminished by 24-hours clopidogrel exposure, whereas P-selectin was not modified. NOS3 downregulated HUVEC model revealed that ICAM-1 modification by clopidogrel is dependent of this via, whereas MCP-1 is modulated in an NO-independent form...

Molecular mechanisms of membrane impermeability in clinical isolates of Enterobacteriaceae exposed to imipenem selective pressure.

Intrinsic mechanisms leading to carbapenem-induced membrane impermeability and multidrug resistance are poorly understood in clinical isolates of Enterobacteriaceae. In this study, molecular behaviours during the establishment of membrane impermeability in members of the Enterobacteriaceae family under imipenem selective pressure were investigated. Clinical isolates (n = 22) exhibiting susceptibility to multiple antibiotics or characterised as extended-spectrum ß-lactamase (ESBL)- or AmpC-producers were submitted to progressive passages on Mueller-Hinton agar plates containing subclinical concentrations of imipenem [0.5 × the minimum inhibitory concentration (MIC)]. Changes in outer membrane permeability were evaluated by determination of antimicrobial MICs, sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), and gene expression analysis related to membrane permeability (i.e. omp35-like, omp36-like and acrA) and regulatory mechanisms (i.e. marA and ompR) by quantitative reverse transcription PCR. Following imipenem induction, 73% of isolates showed increased carbapenem MICs by ≥2 doubling dilutions. At an early stage of treatment, imipenem modulated the expression of porins and efflux pump genes, represented by a reduction of 78% in omp36-like and a two-fold increase in acrA expression. Transcriptional factors marA and ompR were also affected by imipenem induction, increasing mRNA expression by 14- and 4-fold, respectively. High marA expression levels were associated with higher values of acrA expression. These results suggest that imipenem is an important factor in the development of an adaptive response to carbapenems by regulating key genes involved in the control of efflux pumps and porins, which could lead to a multidrug-resistant profile in clinical isolates, contributing to possible treatment failure.

Complete nucleotide sequences of two blaKPC-2-bearing IncN Plasmids isolated from sequence type 442 Klebsiella pneumoniae clinical strains four years apart.

We sequenced the oldest blaKPC-2-bearing plasmid isolated in Brazil and another plasmid also carried by a Klebsiella pneumoniae strain of sequence type 442 (ST442), isolated 52 months later. Both plasmids present an IncN backbone and few acquired regions. Because the 2005 plasmid presented deletions and a truncated gene within Tn4401b compared to the 2009 plasmid, we can thus infer that IncN blaKPC-2-bearing plasmids pFCF1305 and pFCF3SP had a common ancestor circulating in Brazil prior to May 2005.