Biosynthesis of photostable CdS quantum dots by UV-resistant psychrotolerant bacteria isolated from Union Glacier, Antarctica.

BACKGROUND: Quantum Dots (QDs) are fluorescent nanoparticles with exceptional optical and optoelectronic properties, finding widespread utility in diverse industrial applications. Presently, chemically synthesized QDs are employed in solar cells, bioimaging, and various technological domains. However, many applications demand QDs with prolonged lifespans under conditions of high-energy radiation. Over the past decade, microbial biosynthesis of nanomaterials has emerged as a sustainable and cost-effective process. In this context, the utilization of extremophile microorganisms for synthesizing QDs with unique properties has recently been reported. RESULTS: In this study, UV-resistant bacteria were isolated from one of the most extreme environments in Antarctica, Union Glacier at the Ellsworth Mountains. Bacterial isolates, identified through 16 S sequencing, belong to the genera Rhodococcus, Pseudarthrobacter, and Arthrobacter. Notably, Rhodococcus sp. (EXRC-4 A-4), Pseudarthrobacter sp. (RC-2-3), and Arthrobacter sp. (EH-1B-1) tolerate UV-C radiation doses ≥ 120 J/m². Isolated UV-resistant bacteria biosynthesized CdS QDs with fluorescence intensities 4 to 8 times higher than those biosynthesized by E. coli, a mesophilic organism tolerating low doses of UV radiation. Transmission electron microscopy (TEM) analysis determined QD sizes ranging from 6 to 23 nm, and Fourier-transform infrared (FTIR) analysis demonstrated the presence of biomolecules. QDs produced by UV-resistant Antarctic bacteria exhibit high photostability after exposure to UV-B radiation, particularly in comparison to those biosynthesized by E. coli. Interestingly, red fluorescence-emitting QDs biosynthesized by Rhodococcus sp. (EXRC-4 A-4) and Arthrobacter sp. (EH-1B-1) increased their fluorescence emission after irradiation. Analysis of methylene blue degradation after exposure to irradiated QDs biosynthesized by UV-resistant bacteria, indicates that the QDs transfer their electrons to O2 for the formation of reactive oxygen species (ROS) at different levels. CONCLUSIONS: UV-resistant Antarctic bacteria represent a novel alternative for the sustainable generation of nanostructures with increased radiation tolerance-two characteristics favoring their potential application in technologies requiring continuous exposure to high-energy radiation.

Biosynthesis of Cu-In-S Nanoparticles by a Yeast Isolated from Union Glacier, Antarctica: A Platform for Enhanced Quantum Dot-Sensitized Solar Cells.

In recent years, the utilization of extremophile microorganisms for the synthesis of metal nanoparticles, featuring enhanced properties and diverse compositions, has emerged as a sustainable strategy to generate high-quality nanomaterials with unique characteristics. Our study focuses on the biosynthesis of Cu-In-S (CIS) nanoparticles, which has garnered considerable attention in the past decade due to their low toxicity and versatile applications in biomedicine and solar cells. Despite this interest, there is a notable absence of reports on biological methods for CIS nanoparticle synthesis. In this research, three yeast species were isolated from soil samples in an extreme Antarctic environment-Union Glacier, Ellsworth Mountains. Among these isolates, Filobasidium stepposum demonstrated the capability to biosynthesize CIS nanoparticles when exposed to copper sulfate, indium chloride, glutathione, and cysteine. Subsequent purification and spectroscopic characterization confirmed the presence of characteristic absorbance and fluorescence peaks for CIS nanoparticles at 500 and 650 nm, respectively. Transmission electron microscopy analysis revealed the synthesis of monodisperse nanoparticles with a size range of 3-5 nm. Energy dispersive X-ray spectroscopy confirmed the composition of the nanoparticles, revealing the presence of copper, indium, and sulfur. The copper/indium ratio ranged from 0.15 to 0.27, depending on the reaction time. The biosynthesized CIS nanoparticles showed higher photostability than biomimetic nanoparticles and demonstrated successful application as photosensitizers in quantum dot-sensitized solar cells (QDSSC), achieving a conversion efficiency of up to 0.0247%. In summary, this work presents a cost-effective, straightforward, and environmentally friendly method for CIS nanoparticle synthesis. Furthermore, it constitutes the first documented instance of a biological procedure for producing these nanoparticles, opening avenues for the development of environmentally sustainable solar cells.

Efectos de una Charla Antitabaco en Adolescentes Fumadores de Colegios Públicos y Privados en la Región Metropolitana de Santiago de Chile / Effects of an Anti-Smoking talk on Adolescent Smokers in Public and Private Schools in the Metropolitan Region of Santiago de Chile

Introducción. El tabaquismo es responsable de una gran cantidad de muertes en el mundo, la gran prevalencia del tabaquismo entre adolescentes, así como la baja edad de inicio del consumo, genera preocupación y la necesidad de implementar intervenciones específicas a esta población. Objetivo. Evaluar los efectos de una charla antitabaco en adolescentes de colegios públicos y privados en la Región Metropolitana de Santiago. Métodos. Estudio cuantitativo cuasi-experimental, se realizó una charla antitabaco en dos colegios (público y privado), se evaluó la motivación para dejar de fumar con el Test de Richmond en una muestra de 13 estudiantes pre y post charla. Resultados. hubo una mejora en los puntajes de Richmond post charla en ambos colegios, siendo mayor en el colegio público, sin embargo, la diferencia no fue estadísticamente significativa (p=0,09). Discusión. La evidencia respalda la efectividad de las charlas antitabaco. Existe una relación entre nivel socioeconómico y tabaquismo, sin embargo, no hay otros estudios que comparen la efectividad en los distintos estratos sociales. Se reconocen limitaciones del estudio como el tamaño de la muestra y el muestreo no aleatorio, se recomiendan nuevos estudios que incluyan otras variables. Conclusiones. A pesar de limitaciones del estudio, se respalda la implementación de charlas antitabaco en entornos educativos, enfatizando la necesidad de adaptar estrategias a contextos socioeconómicos específicos para mejorar la salud pública.

Background. Introduction: Smoking is responsible for a significant number of deaths worldwide, and the high prevalence of smoking among adolescents, as well as early age of onset, raises concerns, and the need of targeted interventions for this group. The aim of this study was to assess the effects of an anti-smoking talk on students from public and private schools in the Metropolitan Region of Santiago. Methods. A quasi-experimental quantitative study involving an anti-smoking talk in two schools (public and private) assessed the motivation to quit smoking using the Richmond Test in a sample of 13 students pre and post the talk. Results. There was an improvement in Richmond scores post-talk in both schools, with a greater increase observed in the public school. However, the difference was not statistically significant (p=0.09). Discussion. The evidence supports the effectiveness of anti-smoking talks. A relationship between socioeconomic status and smoking exists, yet there are no studies comparing effectiveness across different socioeconomic strata. Study limitations, such as sample size and non-random sampling, are acknowledged, and further research incorporating additional variables is recommended. Conclusions. Despite study limitations, advocating for the implementation of anti-smoking talks in educational settings is supported, emphasizing the need to adapt strategies to specific socioeconomic contexts to enhance public health.

Minicells as an Escherichia coli mechanism for the accumulation and disposal of fluorescent cadmium sulphide nanoparticles.

BACKGROUND: Bacterial biosynthesis of fluorescent nanoparticles or quantum dots (QDs) has emerged as a unique mechanism for heavy metal tolerance. However, the physiological pathways governing the removal of QDs from bacterial cells remains elusive. This study investigates the role of minicells, previously identified as a means of eliminating damaged proteins and enhancing bacterial resistance to stress. Building on our prior work, which unveiled the formation of minicells during cadmium QDs biosynthesis in Escherichia coli, we hypothesize that minicells serve as a mechanism for the accumulation and detoxification of QDs in bacterial cells. RESULTS: Intracellular biosynthesis of CdS QDs was performed in E. coli mutants ΔminC and ΔminCDE, known for their minicell-producing capabilities. Fluorescence microscopy analysis demonstrated that the generated minicells exhibited fluorescence emission, indicative of QD loading. Transmission electron microscopy (TEM) confirmed the presence of nanoparticles in minicells, while energy dispersive spectroscopy (EDS) revealed the coexistence of cadmium and sulfur. Cadmium quantification through flame atomic absorption spectrometry (FAAS) demonstrated that minicells accumulated a higher cadmium content compared to rod cells. Moreover, fluorescence intensity analysis suggested that minicells accumulated a greater quantity of fluorescent nanoparticles, underscoring their efficacy in QD removal. Biosynthesis dynamics in minicell-producing strains indicated that biosynthesized QDs maintained high fluorescence intensity even during prolonged biosynthesis times, suggesting continuous QD clearance in minicells. CONCLUSIONS: These findings support a model wherein E. coli utilizes minicells for the accumulation and removal of nanoparticles, highlighting their physiological role in eliminating harmful elements and maintaining cellular fitness. Additionally, this biosynthesis system presents an opportunity for generating minicell-coated nanoparticles with enhanced biocompatibility for diverse applications.

Toxicity Mechanisms of Copper Nanoparticles and Copper Surfaces on Bacterial Cells and Viruses.

Copper is a metal historically used to prevent infections. One of the most relevant challenges in modern society are infectious disease outbreaks, where copper-based technologies can play a significant role. Currently, copper nanoparticles and surfaces are the most common antimicrobial copper-based technologies. Despite the widespread use of copper on nanoparticles and surfaces, the toxicity mechanism(s) explaining their unique antimicrobial properties are not entirely known. In general, toxicity effects described in bacteria and fungi involve the rupture of membranes, accumulation of ions inside the cell, protein inactivation, and DNA damage. A few studies have associated Cu-toxicity with ROS production and genetic material degradation in viruses. Therefore, understanding the mechanisms of the toxicity of copper nanoparticles and surfaces will contribute to developing and implementing efficient antimicrobial technologies to combat old and new infectious agents that can lead to disease outbreaks such as COVID-19. This review summarizes the current knowledge regarding the microbial toxicity of copper nanoparticles and surfaces and the gaps in this knowledge. In addition, we discuss potential applications derived from discovering new elements of copper toxicity, such as using different molecules or modifications to potentiate toxicity or antimicrobial specificity.

The Bangor Gambling Task: Computerized replication and reappraisal of an emotion-based decision task.

Emotion-based decision making (EBDM) is the capacity to make decisions based on prior emotional consequences of actions. Several neuropsychological tasks, using different gambling paradigms and with different levels of complexity, have been designed to assess EBDM. The Bangor Gambling Task (BGT) was created as a brief and simple card gambling-task to assess EBDM. BGT contains a single-card deck and requires participants to decide whether to gamble or not, which can result in wins or losses. Unknown to the participant, the winning probabilities decrease throughout the task (from 0.75 in the first block to 0.25 in the fifth block), requiring participants to reduce their gambling probability to avoid long-term losses. A few studies have offered evidence regarding the BGT convergent validity. However, there are no computerized versions of BGT available, thus slowing the process of gathering information to explore the EBDM mechanisms behind the task, its validity, and clinical usefulness. In this article, we present a computerized version of the BGT using the Matlab environment and make all our code available. We explore BGT's replicability and analyze its probabilistic structure, providing trial-level and block-level analyses. Eighty-one participants performed the computerized version, which followed the same structure as the original version. It took participants 8.5 ± 3.3 minutes to complete the task, which is faster than the paper version. Replicating previous studies, participants diminished their gambling probability throughout the task, learning to inhibit the initially rewarded gambling behavior. This change in gambling probability could be considered a proxy for EBDM. Our analyses suggest that the last blocks are especially sensitive to capturing deficits in EBDM, and we propose some modifications to BGT's original version to enhance the initial exploratory and learning phase. Our results show that the BGT constitutes a quick and simple task to evaluate EBDM capacities.

Effect of Co-contamination by PAHs and Heavy Metals on Bacterial Communities of Diesel Contaminated Soils of South Shetland Islands, Antarctica.

Diesel oil is the main source of energy used in Antarctica. Since diesel is composed of toxic compounds such as polycyclic aromatic hydrocarbons (PAHs) and heavy metals, it represents a constant threat to the organisms inhabiting this continent. In the present study, we characterized the chemical and biological parameters of diesel-exposed soils obtained from King George Island in Antarctica. Contaminated soils present PAH concentrations 1000 times higher than non-exposed soils. Some contaminated soil samples also exhibited high concentrations of cadmium and lead. A 16S metagenome analysis revealed the effect of co-contamination on bacterial communities. An increase in the relative abundance of bacteria known as PAH degraders or metal resistant was determined in co-contaminated soils. Accordingly, the soil containing higher amounts of PAHs exhibited increased dehydrogenase activity than control soils, suggesting that the microorganisms present can metabolize diesel. The inhibitory effect on soil metabolism produced by cadmium was lower in diesel-contaminated soils. Moreover, diesel-contaminated soils contain higher amounts of cultivable heterotrophic, cadmium-tolerant, and PAH-degrading bacteria than control soils. Obtained results indicate that diesel contamination at King George island has affected microbial communities, favoring the presence of microorganisms capable of utilizing PAHs as a carbon source, even in the presence of heavy metals.

Aspiración manual endouterina (AMEU): Revisión de la literatura y estudio de serie de casos / Manual vacuum aspiration (MVA): a literature review and a case series study

Introducción y objetivo El aborto es la pérdida del producto de la concepción antes de la viabilidad fetal y se considera la principal complicación del embarazo. El objetivo de nuestro trabajo es evaluar los resultados iniciales y en mediano plazo del manejo con Aspiración Manual Endouterina (AMEU) del aborto en el primer trimestre. Métodos Análisis estadístico de serie de casos de 53 pacientes sometidas a AMEU en el Hospital Carlos Van Buren, Valparaíso desde noviembre 2017 a junio 2018 por aborto del primer trimestre. El diagnóstico fue clínico y mediante ultrasonografía. Se efectuó un cuestionario de satisfacción posterior al procedimiento. Resultados Se analizaron 53 pacientes, cuya edad promedio es de 29 años, 19 nulíparas, 34 multíparas, con edad gestacional promedio de 8 semanas. Se analizaron 53 biopsias de contenido intrauterino que resultaron en 53 abortos, de éstos 39 retenidos y 14 incompletos. Se registró un 3% de complicaciones (1 caso de perforación uterina que sólo requirió manejo médico y 1 caso de evacuación incompleta). El cuestionario reveló en una mayoría, el alivio de los síntomas y satisfacción en relación al procedimiento. Conclusión La AMEU es una buena alternativa en el manejo del aborto debido a menores costos, baja tasa de complicaciones y alta eficacia. Los centros que disponen de diversas alternativas para el manejo del aborto deben asegurarse de que la mujer participe activamente en la elección en cuanto a su resolución.

ABSTRACT Introduction and objective Miscarriage is the loss of the product of conception before fetal viability and it is considered the main complication of pregnancy. The main objective of our study is to evaluate initial and midterm reports using Manual Vacuum Aspiration (MVA) as management of first trimester miscarriage. Methods Statistic analysis of a case series of 53 patients submitted to MVA at Hospital Carlos Van Buren, Valparaíso since November 2017 until June 2018 with first trimester miscarriage. The diagnosis was clinical and ultrasonographic. A post procedure satisfaction questionnaire was carried out. Results Fifty-three patients were analyzed, with mean age of 29 years, 19 were nulliparous, 34 multiparous, mean gestational age of 8 weeks. Fifty-three intrauterine biopsies were analyzed, of which 53 were miscarriage, 39 retained sacs and 14 incomplete. We had 3% of complications (1 case of uterine perforation requiring only medical treatment and 1 case incomplete vacuum). The questionnaire revealed in a majority, the relief of symptoms and satisfaction with the procedure. Conclusion MVA is a good alternative in the management of miscarriage due to less costs, low rate of complications and high efficacy. The centres with various alternatives for miscarriage management must ensure that the women actively participates in the election of the resolution.

Response of the biomining Acidithiobacillus ferrooxidans to high cadmium concentrations.

Cadmium is a heavy metal present in contaminated soils. It has no biological role but when entering cells generates DNA damage, overexpression of stress response proteins and misfolded proteins, amongst other deleterious effects. Acidithiobacillus ferrooxidans is an acidophilic bacterium resisting high concentrations of heavy metals such as cadmium. This is important for industrial bioleaching processes where Cd+2 concentrations can be 5-100 mM. Cadmium resistance mechanisms in these microorganisms have not been fully characterized. A. ferrooxidans ATCC 53993 contains genes coding for possible metal resistance determinants such as efflux systems: P-type ATPases, RND transporters and cation diffusion facilitators. In addition, it has extra copies of these genes in its exclusive genomic island (GI). Several of these putative genes were characterized in the present report by determining their transcriptional expression profiles and functionality. Moreover, an iTRAQ proteomic analysis was carried out to explore new cadmium resistance determinants in this bacterium. Changes in iron oxidation components, upregulation of transport proteins and variations in ribosomal protein levels were seen. Finally, increased concentrations of exclusive putative cadmium ATPases present in strain ATCC 53993 GI and other non-identified proteins such as Lferr_0210, forming part of a possible operon, could explain its extreme cadmium resistance. SIGNIFICANCE: Cadmium is a very toxic heavy metal present in mining operations and contaminated environments, it can affect all living organisms, including humans. Therefore, it is important to know the resistance mechanisms of bacteria highly resistant to this metal. These microorganisms in turn, can be used to bioremediate more efficiently environments highly polluted with metals. The results obtained suggest A. ferrooxidans strain ATCC 53993 can be an efficient bacterium to remove cadmium, copper and other metals from contaminated sites.

Paciente haitiana embarazada de alto riesgo y utilidad del US en el diagnóstico diferencial en un PCR: presentación de un caso / High Risk Haitian Pregnant Patient and Utility of the Ultrasound in the Differential Diagnosis in a Cardiac Arrest: A Case Report

In the recent years, have been an increase in the number of pregnant patients of Haitian nationality in the Chilean public health service. This new population has a higher incidence of some pathologies as peripartum cardiomyopathy and sickle cell anemia which impact in the evolution of pregnancy and the anesthetic management of the peripartum. This article presents a case report of a 22 years-old hatian patient, with no known morbid history, who presents cardiac arrest during emergency cesarean section. In addition, it explains the method in which the diagnosis of peripartum cardiomyopathy was obtained, and how the reanimation and the differential diagnoses were guided by the use of ultrasonography. To conclude, it is crucial to develop screening methods to detect high-risk pregnant women and, at the same time, encourage the massification of tools, such as ultrasound [US], to manage critical situations that occurs more frequently in these patients.

Durante el último tiempo ha existido un incremento en el número de pacientes embarazadas de nacionalidad haitiana en el servicio de salud pública chileno. Esta nueva población trae consigo mayor incidencia de algunas patologías como cardiomiopatía del periparto y anemia falciforme, que condicionan la evolución del embarazo y el manejo anestésico del periparto. En este artículo se presenta el caso clínico de una paciente haitiana de 22 años, sin antecedentes mórbidos conocidos, que presenta un paro cardiorrespiratorio durante la cesárea de urgencia. Además, se explica la forma en que se obtuvo el diagnóstico de miocardiopatía del periparto, y cómo se guió la reanimación y los diagnósticos diferenciales mediante el uso de ultrasonografía. En conclusión se destaca que resulta imprescindible desarrollar métodos de screening para detectar embarazadas de alto riesgo y fomentar a su vez la masificación de herramientas, como el ultrasonido [US], para manejo de situaciones críticas que ocurren en mayor frecuencia en estas pacientes.