Interactions of 3 nm, 8 nm, and 15 nm gold particles with human alveolar epithelial cells : a microscopy study

The inhalation of nanoparticles can cause interactions with pulmonary structures. Human alveolar epithelial cells type II organize the alveolar epithelium and thus can be regarded as barrier against pulmonary nanoparticle uptake. Within the present work, interactions of differently sized gold nanoparticles with A549 cells, a model for type II human alveolar epithelial cells, were studied. The intracellular location of the fluorescently labeled gold particles was analyzed by STED (stimulated emission depletion) and electron microscopy. Gold nanoparticles were detected inside the cell nucleus and the Golgi complex. A nanoparticle accumulation was observed at the perinuclear region. The association of gold nanoparticles and cytoskeletal filaments indicated an active intracellular nanoparticle transport. A vesicle-based transport of gold nanoparticles was revealed by live cell imaging. Besides the intracellular particle location, an impact of gold nanoparticles on cell viability and cell proliferation was studied. Cell-based assays revealed a different cytotoxic potential of the gold nanoparticle sizes used. The last part of the work describes the development of an approach of correlative light and electron microscopy (CLEM) for studying nanoparticle-cell interactions. The used method allowed for a correlative imaging of the nanoparticle fluorescence in relation to the nanoparticle core.Die Inhalation von Nanopartikeln kann eine Interaktion mit pulmonalen Strukturen zur Folge haben. Humane alveolare Typ II Epithelzellen kleiden die Lungenbläschen aus und stellen dadurch eine wichtige Barriere für das Eindringen von Nanopartikel in die Lunge sowie in den menschlichen Organismus dar. Die vorliegende Arbeit befasst sich deshalb mit der Interaktion von Goldnanopartikeln verschiedener Größe mit A549 Zellen, einem Modellsystem für humane alveolare Typ II Epithelzellen. Die zelluläre Lokalisation der fluoreszenzmarkierten Goldpartikel wurde durch hochauflösende Mikroskopiemethoden, wie STED (stimulated emission depletion) - Mikroskopie und Elektronenmikroskopie bestimmt. Die Nanopartikel konnten im Zellkern sowie im Golgi - Apparat nachgewiesen werden. Die Akkumulation der Partikel in Zellkernnähe sowie die Assoziation von Goldnanopartikeln mit dem Zytoskelett ließen außerdem einen aktiven intrazellulären Nanopartikeltransport vermuten. Ein Vesikel-basierter Transport der Goldnanopartikel konnte durch Lebendzellmikroskopie bestätigt werden. Neben der Partikellokalisation wurde die Auswirkung der Goldnanopartikel auf die Vitalität und Proliferation von A549 Zellen untersucht. Die eingesetzten Zell-basierten Assays zeigten ein unterschiedliches zytotoxisches Potential der verwendeten Partikelgrößen. Den Abschluss der Arbeit bildete die Entwicklung eines korrelativen Mikroskopieansatzes, der die Detektion der Nanopartikelfluoreszenz in Abhängigkeit des Partikelkerns erlaubte

Optimistic fair transaction processing in mobile ad-hoc networks

Mobile ad-hoc networks (MANETs) are unstable. Link errors, which are considered as an exception in fixed-wired networks must be assumed to be the default case in MANETs. Hence designing fault tolerant systems efficiently offering transactional guarantees in these unstable environments is considerably more complex. The efficient support for such guarantees is essential for business applications, e.g. for the exchange of electronic goods. This class of applications demands for transactional properties such as money and goods atomicity. Within this technical report we present an architecture, which allows for fair and atomic transaction processing in MANETs, together with an associated application that enables exchange of electronic tokens

A correlative analysis of gold nanoparticles internalized by A549 cells

Fluorescently labeled nanoparticles are widely used to investigate nanoparticle cell interactions by fluorescence microscopy. Owing to limited lateral and axial resolution, nanostructures (<100 nm) cannot be resolved by conventional light micro­scopy techniques. Especially after uptake into cells, a common fate of the fluorescence label and the particle core cannot be taken for granted. In this study, a correlative approach is presented to image fluorescently labeled gold nanoparticles inside whole cells by correlative light and electron microscopy (CLEM). This approach allows for detection of the fluorescently labeled particle shell as well as for the gold core in one sample. In this setup, A549 cells are exposed to 8 nm Atto 647N-labeled gold nanoparticles (3.3 × 109 particles mL−1, 0.02 μg Au mL−1) for 5 h and are subsequently imaged by confocal laser scanning microscopy (CLSM) and transmission electron microscopy (TEM). Eight fluorescence signals located at different intracellular positions are further analyzed by TEM. Five of the eight fluorescence spots are correlated with isolated or agglomerated gold nanoparticles. Three fluorescence signals could not be related to the presence of gold, indicating a loss of the particle shell

Hot days and Covid-19: Online survey of nurses and nursing assistants to assess occupational heat stress in Germany during summer 2020

Objectives: Our aim was to identify if working during hot days while wearing Covid-19 related personal protective equipment causes occupational heat stress for nurses and nursing assistants in Germany. Design: Using an online survey, we assessed the impact of hot weather on nurses and nursing assistants working with personal protective equipment. Respondents were recruited by distributing the link to the survey via personal communication, email and various social media channels to nursing staff from hospitals, nursing homes and outpatient care. Results: There were in total 428 participants (18.2% male, 82.5% female), mostly (30.5%) aged between 45 and 55 years. Half of respondents (48.3%) had more than 20 years of experience in nursing. Cardiac, pulmonary, or other pre-existing conditions were reported by 46.2%.Nurses and nursing assistants working in personal protective equipment during hot days were exposed to occupational heat stress. Work was found exhaustive by 96.5% of the participants during those days. 93.0% reported breathing problems and 85.8% reported difficulties with focusing on their work. Many workplaces did not provide adequate heat protection, with distinct differences concerning the amount of prophylactic and heat mitigating measures across institutions. There were significant differences across institutions when it comes to the number of drinks served (p < 0.001), the availability of room thermometers (p < 0.001), the use of mobile cooling devices (p < 0.001) and fans (p < 0.05). Conclusions: Results suggest employers must make more of an effort to provide adequate heat protection for their nursing staff. In order to ensure patient care, there is a need for action; in particular, attention must be paid to the pre-existing health conditions of the nursing staff

Interaktionen von 3 nm, 8 nm und 15 nm Goldpartikeln mit humanen alveolaren Epithelzellen : eine mikroskopische Studie

The inhalation of nanoparticles can cause interactions with pulmonary structures. Human alveolar epithelial cells type II organize the alveolar epithelium and thus can be regarded as barrier against pulmonary nanoparticle uptake. Within the present work, interactions of differently sized gold nanoparticles with A549 cells, a model for type II human alveolar epithelial cells, were studied. The intracellular location of the fluorescently labeled gold particles was analyzed by STED (stimulated emission depletion) and electron microscopy. Gold nanoparticles were detected inside the cell nucleus and the Golgi complex. A nanoparticle accumulation was observed at the perinuclear region. The association of gold nanoparticles and cytoskeletal filaments indicated an active intracellular nanoparticle transport. A vesicle-based transport of gold nanoparticles was revealed by live cell imaging. Besides the intracellular particle location, an impact of gold nanoparticles on cell viability and cell proliferation was studied. Cell-based assays revealed a different cytotoxic potential of the gold nanoparticle sizes used. The last part of the work describes the development of an approach of correlative light and electron microscopy (CLEM) for studying nanoparticle-cell interactions. The used method allowed for a correlative imaging of the nanoparticle fluorescence in relation to the nanoparticle core.Die Inhalation von Nanopartikeln kann eine Interaktion mit pulmonalen Strukturen zur Folge haben. Humane alveolare Typ II Epithelzellen kleiden die Lungenbläschen aus und stellen dadurch eine wichtige Barriere für das Eindringen von Nanopartikel in die Lunge sowie in den menschlichen Organismus dar. Die vorliegende Arbeit befasst sich deshalb mit der Interaktion von Goldnanopartikeln verschiedener Größe mit A549 Zellen, einem Modellsystem für humane alveolare Typ II Epithelzellen. Die zelluläre Lokalisation der fluoreszenzmarkierten Goldpartikel wurde durch hochauflösende Mikroskopiemethoden, wie STED (stimulated emission depletion) - Mikroskopie und Elektronenmikroskopie bestimmt. Die Nanopartikel konnten im Zellkern sowie im Golgi - Apparat nachgewiesen werden. Die Akkumulation der Partikel in Zellkernnähe sowie die Assoziation von Goldnanopartikeln mit dem Zytoskelett ließen außerdem einen aktiven intrazellulären Nanopartikeltransport vermuten. Ein Vesikel-basierter Transport der Goldnanopartikel konnte durch Lebendzellmikroskopie bestätigt werden. Neben der Partikellokalisation wurde die Auswirkung der Goldnanopartikel auf die Vitalität und Proliferation von A549 Zellen untersucht. Die eingesetzten Zell-basierten Assays zeigten ein unterschiedliches zytotoxisches Potential der verwendeten Partikelgrößen. Den Abschluss der Arbeit bildete die Entwicklung eines korrelativen Mikroskopieansatzes, der die Detektion der Nanopartikelfluoreszenz in Abhängigkeit des Partikelkerns erlaubte

Adaptive Data Dissemination in Mobile ad-hoc Networks

Abstract: In this paper we examine data dissemination in MANETs using various push and pull based protocols and a combination of both. We evaluate the protocols considering the load for each node and the resulting data freshness. Furthermore we introduce an adaptive pull protocol which enhances dissemination and saves up to 13% of the network load achieving the same freshness rate as other protocols.

Threshold values of grass pollen (Poaceae) concentrations and increase in emergency department visits, hospital admissions, drug consumption and allergic symptoms in patients with allergic rhinitis: a systematic review

Airborne grass (Poaceae) pollen measurements are used in public warning systems to inform people about the risk of allergic symptoms. However, there is no consensus about which exact thresholds of pollen concentrations provoke the allergic symptoms. The aim of this study was to review the relevant scientific information on the relationship between grass pollen concentrations and the occurrence of emergency department (ED) visits, hospital admissions (HA), drug consumption and allergic symptoms. Literature search was conducted by experts' consultation and snowball strategy. Studies meeting the criteria for inclusion were assessed regarding their risk of bias (RoB). A high RoB resulted in exclusion of the study from data synthesis. Extensive data were extracted and qualitatively compared. The review is registered in PROSPERO. 32 Studies were eligible while 18 showed a low RoB and were qualitatively synthesised. Emergency department visits and hospital admissions were mostly investigated. Threshold values of 10 grains/m(3) and 12 grains/m(3) were reported for ED visits and HA. Evidence exists that an increase of 10 grains/m(3) of air leads to a significant increase in adverse health outcomes. Especially at a three-day lag, adverse health effects were shown. Variations in exposure and outcome measurement make the definition of pollen thresholds difficult. As a consequence, no defined pollen threshold values could be identified. Studies with uniform exposure measures and statistical methods are necessary to gain a better understanding of the impact of grass pollen on human health. Determining personal thresholds could be beneficial for affected people