Square Membrane Resonators Supporting Degenerate Modes of Vibration for High-Throughput Mass Spectrometry of Single Bacterial Cells.

In nanomechanical mass spectrometry, sensing devices are commonly placed in the vacuum environment and a stream of analytes is directed toward the sensor surface for measurement. Beam structures, such as double-clamped nanobeams and nanocantilevers, are commonly used due to their low inertial mass and the simplicity of the analytical models for mass extraction. The drawback of such structures is their low capture areas, compromising the capture efficiency and throughput of this technique. Bi-axisymmetric resonators, such as ultrathin square or circular membranes, arise as an optimal geometry to maximize capture efficiency while minimizing the device inertial mass. However, these structures present degenerate mechanical modes, whose frequency perturbations upon analyte adsorption are not well described by commonly used models. Furthermore, prior knowledge of the vibration mode shapes of the sensor is crucial for the correct calculation of the analyte's mass, and the mode shape of degenerate modes may change significantly after every adsorption event. In this work, we present an accurate analytical theory to describe the effect of mass adsorption on the degenerate modes of square membrane resonators and propose two different methods based on the new theory to update the vibration mode shapes after every adsorption event. Finally, we illustrate the problem experimentally obtaining the mass and adsorption position of individual Escherichia coli K-12 bacterial cells on commercial square silicon nitride membranes fabricated with very small tolerances.

High-throughput determination of dry mass of single bacterial cells by ultrathin membrane resonators.

How bacteria are able to maintain their size remains an open question. Techniques that can measure the biomass (dry mass) of single cells with high precision and high-throughput are demanded to elucidate this question. Here, we present a technological approach that combines the transport, guiding and focusing of individual bacteria from solution to the surface of an ultrathin silicon nitride membrane resonator in vacuum. The resonance frequencies of the membrane undergo abrupt variations at the instants where single cells land on the membrane surface. The resonator design displays a quasi-symmetric rectangular shape with an extraordinary capture area of 0.14 mm2, while maintaining a high mass resolution of 0.7 fg (1 fg = 10-15 g) to precisely resolve the dry mass of single cells. The small rectangularity of the membrane provides unprecedented frequency density of vibration modes that enables to retrieve the mass of individual cells with high accuracy by specially developed inverse problem theory. We apply this approach for profiling the dry mass distribution in Staphylococcus epidermidis and Escherichia coli cells. The technique allows the determination of the dry mass of single bacterial cells with an accuracy of about 1% at an unparalleled throughput of 20 cells/min. Finally, we revisit Koch & Schaechter model developed during 60 s to assess the intrinsic sources of stochasticity that originate cell size heterogeneity in steady-state populations. The results reveal the importance of mass resolution to correctly describe these mechanisms.

Hydrodynamic assisted multiparametric particle spectrometry.

The real-time analysis of single analytes in flow is becoming increasingly relevant in cell biology. In this work, we theoretically predict and experimentally demonstrate hydrodynamic focusing with hollow nanomechanical resonators by using an interferometric system which allows the optical probing of flowing particles and tracking of the fundamental mechanical mode of the resonator. We have characterized the hydrodynamic forces acting on the particles, which will determine their velocity depending on their diameter. By using the parameters simultaneously acquired: frequency shift, velocity and reflectivity, we can unambiguously classify flowing particles in real-time, allowing the measurement of the mass density: 1.35 ± 0.07 g·mL-1 for PMMA and 1.7 ± 0.2 g·mL-1 for silica particles, which perfectly agrees with the nominal values. Once we have tested our technique, MCF-7 human breast adenocarcinoma cells are characterized (1.11 ± 0.08 g·mL-1) with high throughput (300 cells/minute) observing a dependency with their size, opening the door for individual cell cycle studies.

Publisher Correction: Optomechanical detection of vibration modes of a single bacterium.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Optomechanical detection of vibration modes of a single bacterium.

Low-frequency vibration modes of biological particles, such as proteins, viruses and bacteria, involve coherent collective vibrations at frequencies in the terahertz and gigahertz domains. These vibration modes carry information on their structure and mechanical properties, which are good indicators of their biological state. In this work, we harnessed a particular regime in the physics of coupled mechanical resonators to directly measure these low-frequency mechanical resonances of a single bacterium. We deposit the bacterium on the surface of an ultrahigh frequency optomechanical disk resonator in ambient conditions. The vibration modes of the disk and bacterium hybridize when their associated frequencies are similar. We developed a general theoretical framework to describe this coupling, which allows us to retrieve the eigenfrequencies and mechanical loss of the bacterium low-frequency vibration modes (quality factor). Additionally, we analysed the effect of hydration on these vibrational modes. This work demonstrates that ultrahigh frequency optomechanical resonators can be used for vibrational spectrometry with the unique capability to obtain information on single biological entities.

Efectos de la quimioterapia y radioterapia en el desarrollo del niño y seguimiento de enfermería: revisión bibliográfica / Effects of chemotherapy and radiotherapy on child development and nursing follow-up: review of the literature

INTRODUCCIÓN: La supervivencia de cáncer infantil a los 5 años está aumentando gracias a los tratamientos existentes; no obstante, los efectos de esta enfermedad y su tratamiento siguen causando grandes afectaciones en todo el organismo. OBJETIVOS: Conocer cómo afecta la quimioterapia y radioterapia al crecimiento y desarrollo del niño a corto y largo plazo. Identificar si en el seguimiento enfermero pediátrico se tienen en cuenta los efectos de este tratamiento en la valoración del niño. METODOLOGÍA: Tipo de estudio: Revisión bibliográfica. Bases de datos: PUBMED, CINAHL, CUIDATGE y CUIDEN. Para una estrategia de búsqueda exhaustiva se utilizó la combinación de filtros (artículos de los últimos 6 años, idioma español o inglés), truncamientos, operadores lógicos, subtemas y thesaurus. RESULTADOS: Se obtuvieron 29 referencias. Estas se clasificaron en función de los sistemas corporales afectados por el tratamiento y del desarrollo y crecimiento en la edad pediátrica. Se añadió una segunda clasificación en función del método de seguimiento utilizado por las enfermeras. DISCUSIÓN: El análisis de los resultados aporta grandes similitudes y diferencias entre autores, así como en el seguimiento enfermero de los pacientes pediátricos con cáncer, la confrontación ética y legal en la conservación de gónadas y diferencias por edad y sexo. CONCLUSIONES: Actualmente el papel de la enfermera oncológica pediátrica tiene gran importancia por los cuidados proporcionados. Pero existe poca evidencia respecto el seguimiento de los efectos del tratamiento, por lo que es necesario seguir realizando investigación e incrementar conocimiento para reducir complicaciones

INTRODUCTION: Childhood cancer survival at five years old is increasing thanks to existing treatments. However, the effects of this disease and its treatment are still causing major effects throughout the body. OBJECTIVES: Know how chemotherapy and radiotherapy affect growth and development of child in short and long term. Identify if in the pediatric nursing monitoring the effects of this treatments are taken into account in the assessment of the child. METHOD: Type of study: Review of the literature. Databases: PUBMED, CINAHL, CUIDATGE and CUIDEN. The combination of filters (articles from the last 6 years, Spanish or English language), truncation, logical operators, sub themes and thesaurus were used for a thorough search strategy. RESULTS. Twenty-nine references were found. These were classified according to the body systems affected by the treatment, the development and growth in the pediatric age. A second classification was added depending on the monitoring method used by the nurses. CONCLUSIONS: Oncology pediatric nurse paper has a great importance for the care provided at present. There is little evidence in relation to the monitoring of treatment effects so it is necessary to continue making research and increasing knowledge to minimize complications

Mechano-Optical Analysis of Single Cells with Transparent Microcapillary Resonators.

The study of biophysical properties of single cells is becoming increasingly relevant in cell biology and pathology. The measurement and tracking of magnitudes such as cell stiffness, morphology, and mass or refractive index have brought otherwise inaccessible knowledge about cell physiology, as well as innovative methods for high-throughput label-free cell classification. In this work, we present hollow resonator devices based on suspended glass microcapillaries for the simultaneous measurement of single-cell buoyant mass and reflectivity with a throughput of 300 cells/minute. In the experimental methodology presented here, both magnitudes are extracted from the devices' response to a single probe, a focused laser beam that enables simultaneous readout of changes in resonance frequency and reflected optical power of the devices as cells flow within them. Through its application to MCF-7 human breast adenocarcinoma cells and MCF-10A nontumorigenic cells, we demonstrate that this mechano-optical technique can successfully discriminate pathological from healthy cells of the same tissue type.

Melatonin Enhances Cisplatin and Radiation Cytotoxicity in Head and Neck Squamous Cell Carcinoma by Stimulating Mitochondrial ROS Generation, Apoptosis, and Autophagy.

Head and neck cancer is the sixth leading cancer by incidence worldwide. Unfortunately, drug resistance and relapse are the principal limitations of clinical oncology for many patients, and the failure of conventional treatments is an extremely demoralizing experience. It is therefore crucial to find new therapeutic targets and drugs to enhance the cytotoxic effects of conventional treatments without potentiating or offsetting the adverse effects. Melatonin has oncostatic effects, although the mechanisms involved and doses required remain unclear. The purpose of this study is to determine the precise underlying mitochondrial mechanisms of melatonin, which increase the cytotoxicity of oncological treatments, and also to propose new melatonin treatments in order to alleviate and reverse radio- and chemoresistant processes. We analyzed the effects of melatonin on head and neck squamous cell carcinoma (HNSCC) cell lines (Cal-27 and SCC-9), which were treated with 0.1, 0.5, 1, and 1.5 mM melatonin combined with 8 Gy irradiation or 10 µM cisplatin. Clonogenic and MTT assays, as well as autophagy and apoptosis, involving flow cytometry and western blot, were performed in order to determine the cytotoxic effects of the treatments. Mitochondrial function was evaluated by measuring mitochondrial respiration, mtDNA content (RT-PCR), and mitochondrial mass (NAO). ROS production, antioxidant enzyme activity, and GSH/GSSG levels were analyzed using a fluorometric method. We show that high concentrations of melatonin potentiate the cytotoxic effects of radiotherapy and CDDP in HNSCC, which are associated with increased mitochondrial function in these cells. In HNSCC, melatonin induces intracellular ROS, whose accumulation plays an upstream role in mitochondria-mediated apoptosis and autophagy. Our findings indicate that melatonin, at high concentrations, combined with cisplatin and radiotherapy to improve its effectiveness, is a potential adjuvant agent.

Combination of melatonin and rapamycin for head and neck cancer therapy: Suppression of AKT/mTOR pathway activation, and activation of mitophagy and apoptosis via mitochondrial function regulation.

Head and neck squamous cell carcinoma (HNSCC) clearly involves activation of the Akt mammalian target of rapamycin (mTOR) signalling pathway. However, the effectiveness of treatment with the mTOR inhibitor rapamycin is often limited by chemoresistance. Melatonin suppresses neoplastic growth via different mechanisms in a variety of tumours. In this study, we aimed to elucidate the effects of melatonin on rapamycin-induced HNSCC cell death and to identify potential cross-talk pathways. We analysed the dose-dependent effects of melatonin in rapamycin-treated HNSCC cell lines (Cal-27 and SCC-9). These cells were treated with 0.1, 0.5 or 1 mmol/L melatonin combined with 20 nM rapamycin. We further examined the potential synergistic effects of melatonin with rapamycin in Cal-27 xenograft mice. Relationships between inhibition of the mTOR pathway, reactive oxygen species (ROS), and apoptosis and mitophagy reportedly increased the cytotoxic effects of rapamycin in HNSCC. Our results demonstrated that combined treatment with rapamycin and melatonin blocked the negative feedback loop from the specific downstream effector of mTOR activation S6K1 to Akt signalling, which decreased cell viability, proliferation and clonogenic capacity. Interestingly, combined treatment with rapamycin and melatonin-induced changes in mitochondrial function, which were associated with increased ROS production, increasing apoptosis and mitophagy. This led to increase cell death and cellular differentiation. Our data further indicated that melatonin administration reduced rapamycin-associated toxicity to healthy cells. Overall, our findings suggested that melatonin could be used as an adjuvant agent with rapamycin, improving effectiveness while minimizing its side effects.

Higiene del sueño en estudiantes universitarios: conocimientos y hábitos. Revisión de la bibliografía / Sleep hygiene in university students: knowledge and habits. Literature review

Objetivo: Valorar la evidencia existente sobre los conocimientos y la puesta en práctica, por parte de los universitarios, de la higiene del sueño, y si alguno de estos aspectos está relacionada con la calidad del sueño. Diseño: Se ha realizado una revisión bibliográfica utilizando las bases de datos electrónicas PubMed y Google Académico. Inicialmente se localizaron 62 artículos de los cuales, tras realizar un cribado llevado a cabo por dos revisores, permanecieron 12. Se utilizaron como criterios de inclusión que los participantes fuesen universitarios sanos de ambos sexos y que se midiesen la calidad e higiene del sueño, evaluando la asociación entre ambas. Resultados: Los resultados indican que el conocimiento de la higiene del sueño no está relacionado con su práctica (b= 0,04; IC95% -0,03 a 0,11). Sin embargo, el uso de la higiene del sueño sí se ha relacionado con una mejor calidad de este (R2 =0,23; F(1,121)= 36,67; p<0,001). No todos los componentes de la higiene del sueño influyen igualmente sobre la calidad del sueño, relacionándose con una peor calidad los horarios de sueño inapropiados (β=0,27; p<0,001; sr2=0,27) y un ambiente no confortable en el dormitorio (β=0,14; p=0,001; sr2=0,13). Conclusiones: La práctica, y no el conocimiento de la higiene del sueño, es lo que está relacionado con una mejor calidad del sueño. Los componentes que más influyen son el mantenimiento de horarios adecuados y un ambiente más confortable en el dormitorio (AU)

Objective: To assess the existing evidence on university students' knowledge and implementation of sleep hygiene, and whether any of these aspects is related to sleep quality. Design: We conducted a literature review using the electronic databases PubMed and Google Scholar. Initially, 62 papers were located, of which 12 remained in our study after a screening performed by two researchers. The inclusion criteria were: healthy university students (male and female) as study subjects, measures of sleep quality and sleep hygiene, and assessment of the relationship between them. Results: Knowledge of sleep hygiene was not associated with its use (b= 0.04; 95%CI -0.03 to 0.11). However, the use of sleep hygiene was associated with better sleep quality (R2 =0.23; F(1.121)= 36.67; p<0.001). Not all components of sleep hygiene were equally influential on sleep quality. Inappropriate sleep schedules (β=0.27; p<0.001; sr2=0.27) as well as an uncomfortable bedroom environment (β=0.14; p=0.001; sr2=0.13) were related to poorer sleep quality. Conclusions: The implementation of sleep hygiene, rather than knowledge of it, is related to better sleep quality. The most influential components were maintaining appropriate sleep schedules and a comfortable environment in the bedroom (AU)