Ostwald Ripening and Antibacterial Activity of Silver Nanoparticles Capped by Anti-Inflammatory Ligands.

Silver nanoparticles (AgNPs) have been extensively studied during recent decades as antimicrobial agents. However, their stability and antibacterial activity over time have yet to be sufficiently studied. In this work, AgNPs were coated with different stabilizers (naproxen and diclofenac and 5-chlorosalicylic acid) in different concentrations. The suspensions of nanostructures were characterized by transmission electron microscopy, UV-Vis and FT-IR spectroscopic techniques. The antibacterial activity as a function of time was determined through microbiological studies against Staphylococcus aureus. The AgNPs show differences in stabilities when changing the coating agent and its concentration. This fact could be a consequence of the difference in the nature of the interaction between the stabilizer and the surface of the NPs, which were evaluated by FT-IR spectroscopy. In addition, an increase in the size of the nanoparticles was observed after 30 days, which could be related to an Ostwald maturation phenomenon. This result raises new questions about the role that stabilizers play on the surface of NPs, promoting size change in NPs. It is highly probable that the stabilizer functions as a growth controller of the NPs, thus determining an effect on their biological properties. Finally, the antibacterial activity was evaluated over time against the bacterium Staphylococcus aureus. The results showed that the protective or stabilizing agents can play an important role in the antibacterial capacity, the control of the size of the AgNPs and additionally in the stability over time.

Relevance of codetection of respiratory viruses in the severity of acute respiratory infection in hospitalized children. / Relevancia de la co-detección de virus respiratorios en la severidad de la infección respiratoria aguda en niños hospitalizados.

INTRODUCTION: Multiplex polymerase chain reaction (PCR) allows simultaneous detection of respiratory viruses, raising questions about their relevance in the clinical feature. OBJECTIVE: To evaluate the contribution of clinical, epidemiological, and virological factors in the clinical course of children hospitalized due to ARI with viral co-detection. PATIENTS AND METHOD: Pediatric patients ≤ 15 years old, hospitalized due to ARI at the UC-CHRISTUS Health Network Clinical Hospital between June and October 2014, and who presented a positive respiratory molecular panel test, were included. Respiratory samples (nasopharyngeal swab, tracheal aspiration, or bronchoalveolar lavage) with positive panel tests by Seeplex® RV15 OneStep ACE Detection Seegene® technique, were analyzed with a second technique (xTAG-RVP-FASTv2 Luminex®, USA), which allows simultaneous and semi-quantitative detection of 17 respiratory viruses. Clinical and epidemiological records were collected. RESULTS: One virus was identified in 42/57 children (74%) and two or more in 15/57 (26%). Intensive care unit (ICU) hospi talization was significantly more frequent in patients with viral co-detection (OR = 5,5; IC 95%: 1,5 19,6). The most frequently detected viruses were rhinovirus/enterovirus (HRV/EV) (29%) and res piratory syncytial virus (RSV) (25%), and the most common co-detection was HRV/EV-RSV (33%). In x-rays, patients with HRV/EV infection presented interstitial images more frequently, while RSV was associated with condensations (p = 0.002). For HRV/EV, median fluorescence intensity (MFI, semi-quantification) were 1788 and 2456 in co-detection and single agent, respectively (p = 0.022). Children with HRV/EV co-detection had a longer hospital stay compared to isolated identification (5 versus 3 days, p = 0,028). CONCLUSION: In children hospitalized due to ARI, viral co-detection is frequent and associated with more ICU hospitalizations. Our study highlights the presence of HRV/ EV in viral co-detection and longer length of stay. More studies are needed to define the relevance of viral co-detection in hospitalized pediatric patients.

Monocarboxylate transporter 4 (MCT4) is a high affinity transporter capable of exporting lactate in high-lactate microenvironments.

Monocarboxylate transporter 4 (MCT4) is an H+-coupled symporter highly expressed in metastatic tumors and at inflammatory sites undergoing hypoxia or the Warburg effect. At these sites, extracellular lactate contributes to malignancy and immune response evasion. Intriguingly, at 30-40 mm, the reported Km of MCT4 for lactate is more than 1 order of magnitude higher than physiological or even pathological lactate levels. MCT4 is not thought to transport pyruvate. Here we have characterized cell lactate and pyruvate dynamics using the FRET sensors Laconic and Pyronic. Dominant MCT4 permeability was demonstrated in various cell types by pharmacological means and by CRISPR/Cas9-mediated deletion. Respective Km values for lactate uptake were 1.7, 1.2, and 0.7 mm in MDA-MB-231 cells, macrophages, and HEK293 cells expressing recombinant MCT4. In MDA-MB-231 cells MCT4 exhibited a Km for pyruvate of 4.2 mm, as opposed to >150 mm reported previously. Parallel assays with the pH-sensitive dye 2',7'-bis-(carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF) indicated that previous Km estimates based on substrate-induced acidification were severely biased by confounding pH-regulatory mechanisms. Numerical simulation using revised kinetic parameters revealed that MCT4, but not the related transporters MCT1 and MCT2, endows cells with the ability to export lactate in high-lactate microenvironments. In conclusion, MCT4 is a high-affinity lactate transporter with physiologically relevant affinity for pyruvate.

Capping of silver nanoparticles by anti-inflammatory ligands: Antibacterial activity and superoxide anion generation.

Silver nanoparticles (AgNPs) have been widely recognized as antibacterial agents. However, its stability and activity over time have been poorly studied. In this work, the properties and characteristics of differently stabilized AgNPs were evaluated during a span of time. The surface capping agents were diclofenac (d), and ketorolac (k), which currently are used as anti-inflammatory in human medicine. On evaluating the size variation over time, it was observed that the AgNPs-k are the most stable, unlike the non-capped nanoparticles agglomerate and precipitate. UV-Vis spectroscopy analysis showed that the absorbance during time decreases for the three types of nanoparticles, but the decrease is less marked for the two types of anti-inflammatory-capped AgNPs. The rapid loss of the optical prop- erties of bare AgNPs, is mainly due to oxidation, agglomeration, and precipitation of this nanoparticles. The potential cytotoxicity of the AgNPs, evaluated through the formation of the superoxide anion using XXT, showed that both, AgNPs-k and AgNPs-d, generate the radical anion when the samples are irradiated with UV light at 365 nm. This effect appears associated with the capping agents, since the bare nanoparticles did not promote the formation of the superoxide anion. The antibacterial activity of the AgNPs throughout time, against two microorganisms (Escherichia coli and Staphylococcus aureus), was also evaluated. The results showed that capping agents played a decisive role in the antibacterial ability of AgNPs and also in enhancing the antibacterial activity over time.

Stability of Antibacterial Silver Carboxylate Complexes against Staphylococcus epidermidis and Their Cytotoxic Effects.

The antibacterial effects against Staphylococcus epidermidis of five silver carboxylate complexes with anti-inflammatory ligands were studied in order to analyze and compare them in terms of stability (in solution and after exposure to UV light), and their antibacterial and morphological differences. Four effects of the Ag-complexes were evidenced by transmission electronic microscopy (TEM) and scanning electronic microscopy (SEM): DNA condensation, membrane disruption, shedding of cytoplasmic material and silver compound microcrystal penetration of bacteria. 5-Chlorosalicylic acid (5Cl) and sodium 4-aminosalicylate (4A) were the most effective ligands for synthesizing silver complexes with high levels of antibacterial activity. However, Ag-5Cl was the most stable against exposure UV light (365 nm). Cytotoxic effects were tested against two kinds of eukaryotic cells: murine fibroblast cells (T10 1/2) and human epithelial ovarian cancer cells (A2780). The main objective was to identify changes in their antibacterial properties associated with potential decomposition and the implications for clinical applications.

[Parechovirus as etiologic agent of meningitis and/or sepsis like illness in infants]. / Parechovirus como agente etiológico de meningitis y/o sepsis viral en lactantes.

INTRODUCTION: Human parechovirus (HPeV) belongs to the Picornaviridae family and has been described in viral meningoencephalitis and sepsis like illness in infants. Until now, 16 genotypes have been recognized, the most common are HPEV 1, 2 and 3; type 3 is most severe. AIMS: To estimate the frequency of HPEV etiology in viral meningoencephalitis and sepsis in infants and characterize clinical and molecular aspects of infection. METHODS: Between October 2013 and March 2015 we collected CSF samples, plasma, nasopharyngeal swabs and/or stools of patients younger than two years with suspected sepsis and/or viral meningitis. Samples were obtained from laboratory storage sites and from hospitalized patients. HPeV was diagnosed by real-time polymerase chain reaction (PCR) assay against the 5'UTR region. Positive samples were genotyped by sequencing a 304pb segment in VP3/VP1 overlapping region obtained with a nested PCR. RESULTS: Overall HPeV detection rate was 18,6% (11/59 patients), distributed in 8.7% (4/46) laboratory's samples and 53.8% (7/13) of samples from hospitalized patients; mean age was 49 days (18 days-6 months). Most common clinical signs (11/11 patients) were irritability, inappetence, and fever (magnitude 38-38.8°C). All six samples genotyped were HPeV 3 [CORRECTED]. CONCLUSIONS: HPeV should be considered as a relatively significant etiologic agent of viral meningoencephalitis and sepsis in infants.

Parechovirus como agente etiológico de meningitis y/o sepsis viral en lactantes / Parechovirus as etiologic agent of meningitis and/or sepsis like illness in infants

Introduction: Human parechovirus (HPeV) belongs to the Picornaviridae family and has been described in viral meningoencephalitis and sepsis like illness in infants. Until now, 16 genotypes have been recognized, the most common are HPEV 1, 2 and 3; type 3 is most severe. Aims: To estimate the frequency of HPEV etiology in viral meningoencephalitis and sepsis in infants and characterize clinical and molecular aspects of infection. Methods: Between October 2013 and March 2015 we collected CSF samples, plasma, nasopharyngeal swabs and/or stools of patients younger than two years with suspected sepsis and/or viral meningitis. Samples were obtained from laboratory storage sites and from hospitalized patients. HPeV was diagnosed by real-time polymerase chain reaction (PCR) assay against the 5'UTR region. Positive samples were genotyped by sequencing a 304pb segment in VP3/VP1 overlapping region obtained with a nested PCR. Results: Overall HPeV detection rate was 18,6% (11/59 patients), distributed in 8.7% (4/46) laboratory's samples and 53.8% (7/13) of samples from hospitalized patients; mean age was 49 days (SD?). Most common clinical signs were irritability (%), inappetance and fever (algo mas? Magnitude? %). All six samples genotyped were HPeV 3. Conclusions: HPeV should be considered as a relatively significant etiologic agent of viral meningoencephalitis and sepsis in infants.

Introducción: Parechovirus humano (HPeV) pertenece a la familia Picornaviridae; ha sido descrito en sepsis viral y meningoencefalitis en niños de dos años o menos (lactantes). Se conocen 16 genotipos, siendo los más frecuentes HPeV 1, 2 y 3; el más grave es el tipo 3. Objetivos: Estimar la frecuencia de HPeV como agente causal de meningoencefalitis o sepsis viral en lactantes; caracterizar clínica y molecularmente los HPeV encontrados. Material y Métodos: Estudio descriptivo. Se utilizaron muestras de LCR, plasma, hisopado nasofaríngeo y/o deposiciones de lactantes con sospecha de sepsis y/o meningoencefalitis viral entre octubre 2013 y marzo 2015. Se estudiaron muestras almacenadas en laboratorio y de pacientes hospitalizados. Como diagnóstico, se realizó RPC-TR en tiempo real para HPeV dirigido a sector 5'UTR. Para la caracterización molecular, se secuenció un sector de 304 pb en unión VP3/VP1 mediante una RPC-TR anidada. Resultados: Se reclutó un total de 59 pacientes con frecuencia de HPeV de 18,6% (11/59), correspondientes a 8,7% (4/46) en muestras de colección y 53,8% (7/13) en hospitalizados, edad promedio 49 días. En la presentación clínica destacó la irritabilidad, el rechazo alimentario y la fiebre. Seis casos fueron genotipificados, todos correspondieron al tipo HPeV 3. Conclusiones: HPeV debe ser considerado como agente causal en sepsis y/o meningoencefalitis en lactantes.

Prevalence of seven cardiovascular-related genetic polymorphisms in a Chilean mestizo healthy population.

OBJECTIVE: Among the genetic factors associated with cardiovascular disease (CVD), determining polymorphic genotypes could help to understand the appearance of the illness. Ethnic differences in these polymorphisms could explain population variability in susceptibility to CVD. The main goal of this research is to study the presence of more relevant genetic variants of ApoE, CETP, ACE, PAI-1, MTHFR, FII and FVL of the coagulation cascade, to describe the presence of cardiovascular-related variants in a mestizo group of the Chilean people. METHODS AND RESULTS: The studied population comprised 146 unrelated subjects from the general population, diagnosed as healthy, who were genotyped through conventional and/or real-time PCR. The allele frequencies for the Chilean population were: Apo E, ε2: 0.036, ε3: 0.875 and ε4: 0.089; CETP, B1: 0.51 and B2: 0.49; MTHFR, C: 0.52 and T: 0.48; ACE, I: 0.603 and D: 0.397; PAI-1, 4G: 0.381 and 5G: 0.619; FII, G: 0.97 and A: 0.03, and FV Leiden, G: 0.97 and A: 0.03. CONCLUSIONS: This study contributes to establish a first picture in the Chilean mestizo population about the frequencies of these variants, which could act as single or complementary risk factors to trigger CVD. The obtained allele frequencies show great differences in relation to other South American populations.